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Sample records for weakly coordinating solvents

  1. Macrocyclic weakly coordinating anions.

    PubMed

    Landskron, Kai

    2015-10-01

    Herein, the concept of macrocyclic weakly coordinating anions (M-WCAs) is introduced. Synthetic methodologies are described how to access M-WCAs by thermodynamically controlled self-assembly in high yields, in particular through condensation and alkyne metathesis reactions. The anticipated properties and applications of M-WCAs in solid state and in solution are discussed, specifically for gas storage and separation, homogeneous and heterogeneous catalysis, and as liquid and solid electrolytes. PMID:26272789

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

    PubMed

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

    2016-02-01

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

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

    PubMed

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

    2014-01-01

    The modes of action of the commercial solvent extractants used in extractive hydrometallurgy are classified according to whether the recovery process involves the transport of metal cations, M(n+), metalate anions, MXx(n-), or metal salts, MXx into a water-immiscible solvent. Well-established principles of coordination chemistry provide an explanation for the remarkable strengths and selectivities shown by most of these extractants. Reagents which achieve high selectivity when transporting metal cations or metal salts into a water-immiscible solvent usually operate in the inner coordination sphere of the metal and provide donor atom types or dispositions which favour the formation of particularly stable neutral complexes that have high solubility in the hydrocarbons commonly used in recovery processes. In the extraction of metalates, the structures of the neutral assemblies formed in the water-immiscible phase are usually not well defined and the cationic reagents can be assumed to operate in the outer coordination spheres. The formation of secondary bonds in the outer sphere using, for example, electrostatic or H-bonding interactions are favoured by the low polarity of the water-immiscible solvents. PMID:24088789

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

    Engesser, Tobias A; Lichtenthaler, Martin R; Schleep, Mario; Krossing, Ingo

    2016-02-21

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

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

    PubMed Central

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

    2011-01-01

    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

  7. COORDINATION COMPOUND-SOLVENT EXTRACTION PROCESS FOR URANIUM RECOVERY

    DOEpatents

    Reas, W.H.

    1959-03-10

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

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

    PubMed Central

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

    2008-01-01

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

  9. Coordinative properties of highly fluorinated solvents with amino and ether groups.

    PubMed

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

    2005-12-01

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

  10. Dynamic effects of nonequilibrium solvation: Potential and free energy surfaces for Z/E isomerization in solvent-solute coordinates

    NASA Astrophysics Data System (ADS)

    Dhaliwal, Manjinder; Basilevsky, Michael V.; Weinberg, Noham

    2007-06-01

    A novel definition of a solvent coordinate associated with a given reaction is formulated in terms of molecular-dynamic trajectories of the solvent and is applied to discuss the topography of potential energy and free energy surfaces of model liquid phase Z/E isomerization reactions in solvent-solute coordinates. It is shown that the arrangement of the reactant and product valleys on these surfaces can vary from consecutive to parallel, depending on the strength of the solvent-solute interactions.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  12. Polyfluoroalkoxyaluminates and borates as new weakly coordinating anions and as components of battery electrolytes

    NASA Astrophysics Data System (ADS)

    Nolan, Benjamin Garrett

    The synthesis and characterization of salts of new weakly coordinating anions based on the general formulas B(O2Lf)2 - and Al(ORf)4- are reported. New B(O2Lf)2- anions are B(OC(2-C6H4O)(CF3)2) 2-, B(OC(2-(O)-3-C6H3F)(CF 3)2)2-, B(OC(2-(O)-4-C 6H3F)(CF3)2)2- , B(OC(2-(O)-5-C6H3F)(CF3)2 )2-, B(OC(2-(O)-3,5-C6H 2F2)(CF3)2)2- , B(OC(2-(O)-4,5-C6H2F2)(CF 3)2)2-, B(OC(2-(O)-4,6-C 6H2F2)(CF3)2)2 -, B(OC(2-(O)-3,4,5-C6HF3)(CF3) 2)2-, B(OC(2-(O)-4,5,6-C6HF 3)(CF3)2)2-, B(OC(2-(O)-3- t-Bu-5-Me-C6H2)(CF3)2) 2-, B(OC(2-(O)-3,5-C6H2( t-Bu)2)(CF3)2)2 -, B(OC(2-(O)-3-C6H3I)(CF3) 2)2-. Except for HOC(2-C6H 4(OH))(CF3)2, HOC(2-(OH)-4-C6H 3F)(CF3)2, and HOC(2-(OH)-3,5-C6H 2(t-Bu)2)(CF3)2, all of the diols used as ligand precursors in the new borate anions are new compounds. The new LiAl(ORf)4 salts prepared are LiAl(OCH(CF 3)2)4, LiAl(OC(cyclo-C6 H11)(CF3)2)4, and LiAl(OC(C 6H5)(CF3)2)4. Four Li + salts of the new borates and aluminates were structurally characterized by X-ray crystallography: Li(OC(CH3)2)(B(OC(2-(O)-3,4,5-C 6HF3)(CF3)2)2, Li2 (CH3O(CH2)2OCH3)(B(OC(2-C 6H4O)(CF3)2)2), LiAl(OCH(CF 3)2)4, and LiAl(OC(cyclo-C 6H11)(CF3)2)4. Conductivities of solutions of many of the new salts were determined for the solvents in various solvents. Conductivities were also measured for the first time for the known salts LiAl(OC(CH3)(CF3) 2)4, LiAl(OCH(C6H5)(CF3) 2)4, LiAl(OC(4-C6H4(CH3)(CF 3)2)4, LiAl(OC(4-C6H4( t-Bu))(CF3)2)4, LiAl(OC(C6 H5)(CF3)2)4, and LiAl(OC(CF 3)3)4. Based on these measurements, it was determined that all of the anions are more weakly coordinating and more weakly ion-pairing than the commonly-used weakly coordinating anion CF3SO3 -. For the B(O2Lf)2 - anions, it was found that the ion-pairing strength depends not only on the number of fluorine atoms incorporated into the phenyl groups in the anions but also on their relative positions. The maximum conductivity for all LiB(O2Lf)2 salts was observed for a 0.5 M DME solution of LiB(OC(2-(O)-4,5,6-C6HF3)(CF 3)2)2 (8.39 mS cm-1). The maximum value for the LiAl(ORf)4 salts studied was observed for a 0.5 M solution of LiAl(OCH(CF3)2)4 (11.2 mS cm-1). Electrochemical stabilities of the new lithium salts were also examined. Three other classes of weakly coordinating anions were studied in terms of the conductivities of their lithium salts: B(C6F 5)3(ORf)- (ORf = OCH(CF3)2, OC(C6H5)2(CF 3), OC(CF3)3); carborane anions (CB11H 12-, 7,8,9,10,11,12-CB11H6Br 6-, 1-CH3-CB11F11 -); and the anion based on the hydrogen-bonded complex of CF 3CO2- and CF3COOH, H(CF 3CO2)2-.

  13. T-duality as coordinates permutation in double space for weakly curved background

    NASA Astrophysics Data System (ADS)

    Sazdović, B.

    2015-08-01

    In the paper [1] we showed that in double space, where all initial coordinates x μ are doubled x μ → y μ , the T-duality transformations can be performed by exchanging places of some coordinates x a and corresponding dual coordinates y a . Here we generalize this result to the case of weakly curved background where in addition to the extended coordinate we will also transform extended argument of background fields with the same operator . So, in the weakly curved background T-duality leads to the physically equivalent theory and complete set of T-duality transformations form the same group as in the flat background. Therefore, the double space represent all T-dual theories in unified manner.

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

    SciTech Connect

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

    2014-10-15

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

  15. Calculation of Vibrational Spectra of Coordinated Perchlorate Ion in Dipolar Aprotic Solvents

    NASA Astrophysics Data System (ADS)

    Mikhailov, G. P.

    2014-09-01

    The vibrational spectrum of perchlorate ion coordinated to Li+, Na+, and Mg2+ cations in dipolar aprotic solvents (DAS) was studied using Hartree-Fock methods not taking into account (RHF) and accounting partially for electron correlation (MP2) and B3LYP density functional theory within the polarized continuum model (PCM). Experimental and calculated spectrum-structure correlations for coordinated perchlorate-ion complexes in DAS were analyzed. It was found that the best fi t of the experimental and calculated vibrational spectra was achieved by taking into account the electron correlation and non-specific solvation.

  16. Lanthanide Coordination Polymers with 4,4'-Azobenzoic Acid: Enhanced Stability and Magnetocaloric Effect by Removing Guest Solvents.

    PubMed

    Zhang, Shaowei; Duan, Eryue; Han, Zongsu; Li, Leilei; Cheng, Peng

    2015-07-01

    Three lanthanide coordination polymers (Ln-CPs) formulated as [Ln(azdc)(HCOO)]n [Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3); H2azdc = 4,4'-azobenzoic acid] have been successfully obtained by the solvothermal reaction of Ln(III) ions with H2azdc ligands in the mixed solvent N,N-dimethylformamide (DMF)/H2O. Compared with our previous work on Ln-CPs with H2azdc ligands, [Gd2(azdc)3(DMA)2]n·2nDMA (1'; DMA = dimethylacetamide), in which the DMA molecules coordinate to Gd(III) ions that are replaced by HCOO(-) groups in 1, resulting in the distinct structures and properties of the final products. Adjacent Ln(III) ions in 1-3 are connected by HCOO(-) groups through bridging and chelating modes to give 2D layers, which are further linked by azdc(2-) ligands to produce 3D frameworks. Magnetic results declare that antiferromagnetic couplings exist in 1, although two different magnetic interactions among adjacent Gd(III) ions derived from antiferromagnetic interactions of the smaller Gd-O-Gd angles (Gd···Gd distances) and weak ferromagnetic interactions of the larger Gd-O-Gd angles (Gd···Gd distances) coexist in 1. Furthermore, the magnetocaloric effect (MCE) value of 1 is 1.5 times as large as that of 1'. More importantly, 1 exhibits excellent stabilities toward air, thermal, solvent, and acid/alkaline conditions. The results manifest that the crystalline structure of 1 can be stable at at least 425 °C supported by the in situ variable-temperature powder X-ray diffraction patterns and thermogravimetric analyses, in air for at least 3 months, and in common solvents for more than 1 week, as well as in aqueous solutions ranging from pH = 2 to 12 for more than 1 week. PMID:26097991

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Four unexpected 2D lanthanide coordination polymers have been synthesized through in situ reactions of DMF solvent under solvothermal conditions. The isostructural complexes 1-3 contain four types of 21 helical chains. While the Nd(III) ions are bridged through μ2-HIDC2- and oxalate to form a 2D sheet along the bc plane without helical character in 4. Therefore, complex 1 exhibits bright red solid-state phosphorescence upon exposure to UV radiation at room temperature.

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

    PubMed

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

    2014-12-01

    The reactivity and stability of P(III)-N and P(III)≈N bonds will be different towards various solvents, bases, and acids because of their difference in bond strength due to different N-pπ-P-dπ donor bonding. For this, a P≈N containing Pd(II) complex, [Pd(DPAP)2] (C1), was synthesized from the reaction between PdCl2(COD) (COD = 1,4-cyclooctadiene) and 2 equiv. DPAP (diphenyl phosphino amino pyridine) ligand, followed by deprotonation of the N-H proton of the coordinated DPAP. The reactivity and stability of coordinated P≈N in complex C1 were determined in various protic and aprotic solvents, bases, and acids. The inertness of coordinated P=N towards various solvents and bases was observed, whereas protonation occurs at the nitrogen of P=N in the presence of an acid to form P-NH, with the generation of dicationic palladium complexes (C2). The dicationic complex C2 is found to be stable in the presence of bulky monoanionic Sn(IV) reagents, whereas, in the presence of more nucleophilic anions like Br(-) or I(-), dissociation of one DPAP ligand from dicationic Pd(II) complexes C2 leads to the generation of Pd(DPAP)X2 (X = Br(-), I(-)). Finally, the utility of the complexes towards Suzuki coupling of various aryl bromides and aryl or heteraryl boronic acids has been checked. PMID:25312248

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

    PubMed

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

    2014-10-13

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

  20. Weakness

    MedlinePlus

    Lack of strength; Muscle weakness ... feel weak but have no real loss of strength. This is called subjective weakness. It may be ... flu. Or, you may have a loss of strength that can be noted on a physical exam. ...

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

    PubMed

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

    2015-10-26

    An unusual 1D-to-3D transformation of a coordination polymer based on organic linkers containing highly polar push-pull π-conjugated side chains is reported. The coordination polymers are synthesized from zinc nitrate and an organic linker, namely, 2,5-bis{4-[1-(4-nitrophenyl)pyrrolidin-2-yl]butoxy}terephthalic acid, which possesses highly polar (4-nitrophenyl)pyrrolidine groups, with high dipole moments of about 7 D. The coordination polymers exhibit an unusual transformation from a soluble, solvent-stabilized 1D coordination polymer into an insoluble, metal-organic framework (MOF)-like 3D coordination polymer. The coordination polymer exhibits good film-forming ability, and the MOF-like films are insoluble in conventional organic solvents. PMID:26493879

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

    SciTech Connect

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

    2015-05-15

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

  3. Solvent dynamical effects on electron-transfer kinetics: Influence of electronic coupling on weak-overlap exchange processes

    NASA Astrophysics Data System (ADS)

    McManis, George E.; Mishra, A. K.; Weaver, Michael J.

    1987-05-01

    A numerical integration treatment of the appropriate Kramers' diffusion equation, involving overdamped solvent motion, is employed to estimate adiabatic barrier-crossing frequencies νos for weak-overlap electron-exchange processes featuring only outer-shell (solvent) reorganization as a function of the electronic matrix coupling element H12. Comparisons are made with estimates of νos obtained from limiting analytical expressions. The competing influence of reaction nonadiabaticity (i.e., electron tunneling) and solvent motion upon the barrier-crossing frequency is also considered as a function of H12 using a Landau-Zener treatment. The results indicate that the dominant influence of overdamped solvent motion on the preexponential factor, that yields the observed inverse correlation between the reaction rate and the solvent longitudinal relaxation time, requires reactions that feature moderate degrees of electronic coupling, around H12≳0.1 kcal mol-1, in most common polar solvents. These factors are briefly illustrated with reference to recent measurements of the solvent-dependent kinetics of cobalticinium-cobaltocene electrochemical exchange.

  4. Research reveals co-ordination and collaboration strengths and weaknesses in population education.

    PubMed

    1991-01-01

    The strengths and weaknesses of population education programs in Sri Lanka, Nepal, and the Maldives, based on descriptive research studies, are identified. The research topics were devised at a Subregional Meeting on Joint Research studies in Population Education for South Asia Subregion in 1990, as well as motivational strategies for promoting the small family norm in Bangladesh and Pakistan. Results were presented at a 1991 meeting held in UNESCO PROAP. The results were that 3 very different collaborative modalities operate in these countries. Sri Lanka had a formal national population committee for coordinating functions. The Maldives had no national formal structures, but there were linkages between population programs. Nepal had a formal structure but had failures in coordination. The Sri Lanka Population Committee, which began in 1972, established population education when the entire educational system was being reformed. The curriculum development committee consisted of representatives from a variety of disciplines and worked as a cohesive unit. As a consequence, junior secondary schools taught population education in such courses as social studies and science. Regional departments of education provided inservice training to the junior secondary school teachers. At the policy level, the education plan of 1972/73-77 was implemented within the National 5 Year Plan and the Population Committee functioned under a senior government Minister, which provided greater credibility and implementation. It also ensured linkage with other departments, agencies, and development programs. In the Maldives, the linkage was between the Population Education Program of the Educational Development Center (EDC) and the Allied Health Service Training Center's (AHSTC) child-spacing program. The small scale size may be a factor in the coordination and resource sharing and effective linkages without a formal national committee umbrella. The weakness was in multiplicity of effort, particularly i orientation. The recommendation was to do joint planning. Nepal's program needs coordination and linkages at the implementation level. There was breakdown in coordination and collaboration. Recommendations were to eliminate training and implementation from the Coordinator's Office and institute coordinating roles only, and to coordinate field programs by using CTSDC trained teachers in AES training. Content changes were also needed in linking community development and resource issues with nonformal population education, and consistency in materials used at the Certificate and Bachelor's level. Book revision needs to include population education content. Guidelines and manuals based on these research studies are planned for the future. PMID:12285079

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

    SciTech Connect

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

    2015-10-15

    Three magnesium based metal-organic frameworks, Mg{sub 3}(3,5-PDC){sub 3}(DMF){sub 3} {center_dot} DMF [1], Mg(3,5-PDC)(H{sub 2}O) {center_dot} (H{sub 2}O) [3], and Mg4(3,5-PDC)4(DMF){sub 2}(H{sub 2}O){sub 2} {center_dot} 2DMF {center_dot} 4.5H{sub 2}O [4], and a 2-D coordination polymer, [Mg(3,5-PDC)(H{sub 2}O){sub 2}] [2] [PDC = pyridinedicarboxylate], were synthesized using a combination of DMF, methanol, ethanol, and water. Compound 1 [space group P2{sub 1}/n, a = 12.3475(5) {angstrom}, b = 11.1929(5) {angstrom}, c = 28.6734(12) {angstrom}, {beta} = 98.8160(10){sup o}, V = 3916.0(3) {angstrom}{sup 3}] consists of a combination of isolated and corner-sharing magnesium octahedra connected by the organic linkers to form a 3-D network with a 12.2 {angstrom} x 4.6 {angstrom} 1-D channel. The channel contains coordinated and free DMF molecules. In compound 2 [space group C2/c, a = 9.964(5) {angstrom}, b = 12.0694(6) {angstrom}, c = 7.2763(4) {angstrom}, {beta} = 106.4970(6){sup o}, V = 836.70(6) {angstrom}{sup 3}], PDC connects isolated seven coordinated magnesium polyhedra into a layered structure. Compound 3 [space group P6{sub 1}22, a = 11.479(1) {angstrom}, c = 14.735(3) {angstrom}, V = 1681.7(4) {angstrom}{sup 3}] (previously reported) contains isolated magnesium octahedra connected by the organic linker with each other forming a 3D network. Compound 4 [space group P2{sub 1}/c, a = 13.7442(14) {angstrom}, b = 14.2887(15) {angstrom}, c = 14.1178(14) {angstrom}, {beta} = 104.912(2){sup o}, V = 2679.2(5) {angstrom}{sup 3}] also exhibits a 3D network based on isolated magnesium octahedra with square cavities containing both disordered DMF and water molecules. The structural topologies originate due to the variable coordination ability of solvent molecules with the metal center. Water molecules coordinate with the magnesium metal centers preferably over other polar solvents (DMF, methanol, ethanol) used to synthesize the coordination networks. Despite testing multiple desolvation routes, we were unable to measure BET surface areas greater than 51.9 m{sup 2}/g for compound 1.

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

    SciTech Connect

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

    2011-12-31

    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.

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

    PubMed

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

    2014-03-01

    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

  8. Hydrophobic Encapsulated Phosphonium Salts-Synthesis of Weakly Coordinating Cations and their Application in Wittig Reactions.

    PubMed

    Moritz, Ralf; Wagner, Manfred; Schollmeyer, Dieter; Baumgarten, Martin; Mllen, Klaus

    2015-06-15

    Large and rigid tetraarylphosphonium tetrafluoroborate salts have been synthesized representing weakly coordinating cations with diameters of several nanometers. Divergent dendritic growth by means of thermal Diels-Alder cycloaddition was employed for the construction of the hydrophobic polyphenylene framework up to the third generation. X-ray crystal structure analysis of first-generation phosphonium tetrafluoroborate supported the rigidity of the non-collapsible shell around the phosphorus center and gave insight into solid-state packing and cation-anion distances. Copper(I)-catalyzed azide-alkyne ligation served as reliable method for the preparation of a first-generation triazolylphenyl hybrid phosphonium cation under mild reaction conditions. Furthermore, from the synthesis of triarylbenzylphosphonium bromides, Wittig precursors with unprecedented bulky substituents in the ?-position were accessible. Employment of these precursors under Wittig conditions by treatment with base and subsequent reaction with aldehydes preferentially provided (Z)-olefins with bulky polyphenylene substituents. PMID:25965029

  9. Vibrational effects in a weakly-interacting quantum solvent: The CO molecule in 4He gas and in 4He droplets

    NASA Astrophysics Data System (ADS)

    Paesani, F.; Gianturco, F. A.

    2002-06-01

    The coupling between the intermolecular motion and the internal vibrational coordinate in the He-CO system is computed at the post-Hartree-Fock level using the DFT+DISP model already employed by us for similar systems and reviewed here in the main text. The quality of the computation of such weak effects is compared with other, earlier model calculations and then used for the evaluation of the vibrational relaxation cross sections of the CO molecule diluted in 4He gas. A further assessment of the vibrational coupling is carried out by computing, with a stochastic approach that employs the Diffusion Monte Carlo method, the effects on the vibrational frequency of the CO impurity from its immersion in 4He droplets of variable size. Both sets of results are analyzed and discussed to gauge the reliability of the computed coupling vis-a-vis one of those suggested by earlier calculations. This study provides further evidence on the difficulty of quantitatively obtaining from calculations the extremely small effects connected with molecular vibrational features in this system and caused by the weak interaction between the title molecule and a quantum solvent like 4He.

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

    PubMed Central

    Zeitler, Magteld; Tass, Peter A.

    2016-01-01

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

  11. Solvent-dependent zinc(II) coordination polymers with mixed ligands: selective sorption and fluorescence sensing.

    PubMed

    Hua, Ji-Ai; Zhao, Yue; Kang, Yan-Shang; Lu, Yi; Sun, Wei-Yin

    2015-07-01

    Starting from the same metal salts and mixed organic ligands of 1,3,5-tris(1-imidazolyl)benzene (tib) and 2-bromo-1,4-benzenedicarboxylic acid (H2BDC-Br), two novel zinc(II) coordination polymers [Zn2(tib)2(BDC-Br)]22SO417H2O (1) and [Zn4(tib)2(BDC-Br)3(H2O)4SO4]7.5H2O2.5DMF (2) (DMF = N,N-dimethylformamide) were obtained by using different solvent systems of DMF/H2O and DMF/EtOH/H2O, respectively. 1 is an unusual (3,4)-connected 3D net with a Point symbol of {4810(4)}{4810}, while 2 is a complicated 1D chain, which is further connected to form a 3D supramolecular architecture by hydrogen bonding interactions. In particular, 1 and 2 exhibit selective adsorption of CO2 over N2 and show good selectivity for detection of acetone via fluorescence quenching. PMID:26032187

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

    PubMed

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

    2015-12-01

    We report the most recent results related to application of a metathetic pathway towards mixed-metal borohydrides. The synthetic protocol utilizes highly-fluorinated weakly coordinating anion salts as precursors. We discuss the technicalities related to the use of fluorine-rich anions as well as the improvements which are still needed to deliver high-purity materials with potential applications for hydrogen storage. The applicability of the method is expanded beyond the previously described complex borohydrides of alkali metal Zn or Y, towards the systems containing Mg(II), Sc(III), Mn(II), or Eu(III). We have prepared for the first time [Ph4P]2[Mn(BH4)4] and [Me4N]2[Mg(BH4)4], solved their crystal structures from powder x-ray diffraction, and used selected organic metal borohydride derivatives as precursors towards mixed-metal borohydrides (K2Mn(BH4)4, Rb3Mg(BH4)5, etc.). We have also prepared [Ph4P][Eu(BH4)4], which is the first derivative of Eu(III) in the homoleptic environment of borohydride anions. PMID:26242623

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  14. Ionic Liquids with Weakly Coordinating [M(III)(OR(F))4](-) Anions.

    PubMed

    Rupp, Alexander B A; Krossing, Ingo

    2015-09-15

    Ionic liquids (ILs) are defined as salts with melting points below 100 °C. They attracted much attention in the last two decades due to their unique set of properties, including high conductivities, low viscosities, negligible vapor pressure, and high electrochemical resistance. ILs are seen as tunable systems, of which (also in mixtures) up to 10(19) combinations may exist. These properties make ILs interesting candidates for a variety of fundamental to industrial applications. Our addition to this field was weakly coordinating, little interacting anions, the highly fluorinated aluminates [Al(OR(F))4](-) (R(F) = C(CF3)3, C(CH3), (CF3)2, and CH(CF3)2 and later also CH2(CF3)). We have used these anions in a broad spectrum of applications, including the stabilization of reactive cations, (polymerization) catalysis, and conducting salts for cyclic voltammetry or in electrochemical cells. Especially the [Al(Ohfip)4](-) (hfip = CH(CF3)2) anions in combination with asymmetric organic cations turned out to be very well suited for the synthesis of ILs with very low melting points, some even far below 0 °C. Also the analogous borates, [B(OR(F))4](-), were shown to yield ILs, and currently a plethora of such aluminate and borate ILs have been synthesized and thoroughly investigated. In many aspects, at least the [Al(Ohfip)4](-) ILs present almost ideally noninteracting prototype ILs with (nearly) isotropic but weak and flat Coulomb potential. Consequently, their overall interionic interactions are significantly reduced compared with other classes of ILs, resulting in an extraordinarily low degree, or (for short cation chain lengths below six) even complete absence of ion pairing. From thorough analysis of the principles governing the physical properties of this highly fluorinated IL class with minimized interactions, we were able to learn basic principles that could be extended, for example, to the prediction of the principal properties of a wide variety of typical ILs. In this Account, we give a comprehensive review of their syntheses, thermal and toxicological behavior, physical as well as dynamic properties, and use in electrochemical applications. We delineate advantages and limitations of the [M(III)(OR(F))4](-) ILs developed in our lab and give an outlook on those fields, in which there is still a lack of knowledge. PMID:26299782

  15. Coordination conversion of cobalt(II) in binary aqueous-organic solvents

    SciTech Connect

    Khvostova, N.O.; Karapetyan, G.O.; Yanush, O.V.

    1985-11-01

    It has been shown that the thermochromic conversions of cobalt(II) in binary solvents are influenced by a number of factors: the nature of the solvent, the strength of the complexes of octahedral symmetry formed, the outer-sphere influence of the solvent on the complexes, the form of the anion, the solvation of the participants in the reaction, and the interaction of the components of the solvent with one another. A correlation between the strength and the spectral position of the absorption bands of the complexes of the activator has been established, and a spectroscopic criterion for selecting the solvents has been proposed. The expediency of using binary solvents to create effective thermochromic media with variable phototransmission has been substantiated.

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

    PubMed

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

    2016-03-01

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

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

    PubMed Central

    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

    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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-04-01

    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] (1), [Zn(bpz)(pta)]n (2), [Zn(bpz)(tpa)(H2O)]n (3), [Zn(bpz)(tpa)·4H2O]n (4), and [Zn(bpz)(npa)·H2O]n (5 and 6) (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 1 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 2, 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 3, 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 4 exhibits a chiral two-fold interpenetrated 4-connected qtz network with the point symbol {6(4)·8(2)}. Compounds 5 and 6 are a pair of genuine supramolecular isomers with identical 4-connected dia topology. The three families of compounds, namely, 1/2, 3/4, and 5/6, are structurally controlled by the solvent systems H2O/CH3OH-H2O, H2O/DMF-CH3OH, and CH3OH-H2O/CH3CN-H2O, respectively. Except for the discrete molecule 1, the other five compounds have the same 4-connected coordination networks, but with different topologies ranging from dia (2, 5, 6), cds (3) to qtz (4), 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 1 can be irreversibly transformed from a 0D discrete molecule to an infinite 3D structure (2) 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    PubMed

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

    2016-03-15

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2016-04-11

    Using time-resolved monochromatic high energy X-ray diffraction, we present an in situ study of the solvothermal crystallisation of a new MOF [Yb2 (BDC)3 (DMF)2 ]⋅H2 O (BDC=benzene-1,4-dicarboxylate and DMF=N,N-dimethylformamide) under solvothermal conditions, from mixed water/DMF solvent. Analysis of high resolution powder patterns obtained reveals an evolution of lattice parameters and electron density during the crystallisation process and Rietveld analysis shows that this is due to a gradual topochemical replacement of coordinated solvent molecules. The water initially coordinated to Yb(3+) is replaced by DMF as the reaction progresses. PMID:26959076

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

    PubMed

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

    2005-04-01

    Oculopharyngeal muscular dystrophy (OPMD) is a late-onset disorder caused by a (GCG)n trinucleotide repeat expansion in the poly(A) binding protein nuclear-1 (PABPN1) gene, which in turn leads to an expanded polyalanine tract in the protein. We generated transgenic mice expressing either the wild type or the expanded form of human PABPN1, and transgenic animals with the expanded form showed clear signs of abnormal limb clasping, muscle weakness, coordination deficits, and peripheral nerves alterations. Analysis of mitotic and postmitotic tissues in those transgenic animals revealed ubiquitinated PABPN1-positive intranuclear inclusions (INIs) in neuronal cells. This latter observation led us to test and confirm the presence of similar INIs in postmortem brain sections from an OPMD patient. Our results indicate that expanded PABPN1, presumably via the toxic effects of its polyalanine tract, can lead to inclusion formation and neurodegeneration in both the mouse and the human. PMID:15755680

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

    NASA Astrophysics Data System (ADS)

    Sayin, Koray; Karakaş, Duran

    2014-11-01

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

  6. Effect of Solvent Molecule in Pore for Flexible Porous Coordination Polymer upon Gas Adsorption and Iodine Encapsulation.

    PubMed

    Arıcı, Mürsel; Yeşilel, Okan Zafer; Taş, Murat; Demiral, Hakan

    2015-12-01

    Four new Zn(II)-coordination polymers, namely, [Zn2(μ6-ao2btc)(μ-obix)2]n (1), [Zn2(μ4-ao2btc)(μ-obix)2]n (2), [Zn2(μ4-ao2btc)(μ-mbix)2]n (3), and {[Zn2(μ4-ao2btc)(μ-pbix)2] · 2DMF · 8H2O}n (4), where ao2btc = dioxygenated form of 3,3',5,5'-azobenzenetetracarboxylate and obix, mbix, and pbix = 1,2-, 1,3-, and 1,4-bis(imidazol-1-ylmethyl)benzene, have been synthesized with azobenzenetetracarboxylic acid and isomeric bis(imidazole) ligands and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, powder X-ray diffraction, and thermal analyses. X-ray results showed that 1, 2, and 4 had two-dimensional structures with 3,4L13 topology, while 3 was a three-dimensional coordination polymer with bbf topology. For 4, two types of activation strategies, solvent exchange + heating (which produced 4a) and direct heating (which produced 4b), were used to investigate the effect of a guest molecule in a flexible framework. Gas adsorption and iodine encapsulation properties of activated complexes were studied. The CO2 uptake capacities for 4a and 4b were 3.62% and 9.50%, respectively, and Langmuir surface areas calculated from CO2 isotherms were 167.4 and 350.7 m(2)/g, respectively. Moreover, 4b exhibited 19.65% and 15.27% iodine uptake in vapor phase and cyclohexane solution, respectively, which corresponded to 1.47 and 0.97 molecules of iodine/formula unit, respectively. Moreover, photoluminescence properties of the complexes were studied. PMID:26594910

  7. Exceptional crystallization diversity and solid-state conversions of Cd(II) coordination frameworks with 5-bromonicotinate directed by solvent media.

    PubMed

    Li, Cheng-Peng; Wu, Jing-Min; Du, Miao

    2012-09-24

    A series of nine coordination polymers {[Cd(L)(2)(solvent)(x)](solvent)(y)}(n) have been prepared from Cd(NO(3))(2) and 5-bromonicotinic acid (HL) in different solvents through a layered diffusion method. By using CH(3)OH/H(2)O at different volume ratios of 1:1 and 1:3, a one-dimensional (1D) coordination species (1a) and a three-dimensional (3D) (3,6)-connected framework (2a·g(1)) can be obtained. A similar self-assembly process in C(2)H(5)OH/H(2)O or H(2)O/1,4-dioxane gives 2a·g(2) or 2a·g(3), which are isomorphic to 2a·g(1) but with different lattice solvents. Replacement of the mixed solvents with DMF/H(2)O (v/v 1:1 or 1:3) also gives a 1D chain complex (1b) or a 3D microporous framework (2b·g(1)). Similarly, MOF 2b·g(2) can be assembled from CH(3)CN/H(2)O as an isomorphic solvate of 2b·g(1). Significantly, the 3D MOF families of 2a·g(n) and 2b·g(n) are supramolecular isomers even though they are topologically equivalent. Also, if a mixture of CH(3)OH/CH(2)Cl(2) (v/v 1:1 or 3:1) is used, a pair of distinct MOFs (3a·g) and (3b) are generated as pseudo-polymorphs that show a two-dimensional (2D) sheet and a 3D coordination framework, respectively. Furthermore, mutual solvent-induced conversions were realized between 1a and 1b and between 2a·g(1), 2a·g(2), and 2a·g(3) following the size-dependent rule of the solvent. These results are of great significance in recognizing the solvent effect upon coordination assemblies and their crystal transformations. PMID:22930554

  8. Induced morphology control of Ln-asparagine coordination polymers from the macro to nanoscopic regime in polar solvent-water mixtures.

    PubMed

    Yang, Ming; Shen, Zhurui; Chen, Tiehong; Bi, Huichao; Yang, Bin; Xu, Wei

    2013-01-28

    A bottom-up approach is presented here for morphology control of Ln-asparagine (Asn) coordination polymers (CPs) from the macro to nanoscopic regime by tuning solvent polarity based on the π* solvent polarity scale in polar solvent-water mixed solutions. By a simple hydrothermal treatment, large macroporous spheres with sizes up to millimeters were obtained in ethanol (π*: 0.54)-water mixtures, and their formation mechanism was proved to be particle aggregation together with a hollowing process based on Ostwald ripening. Other solvents with increasing polarity were also used, and submicrometer spheres as well as fine nanoparticles were prepared in acetone (π*: 0.71) and DMF (π*: 0.88), respectively. When dioxane (π*: 0.55) was used here, whose π* value is similar to ethanol, large macroporous spheres were also prepared. Furthermore, with Ce- and La-Asn CPs large spheres as precursors, after calcination, ceria and lanthana large spheres with hierarchical structures were fabricated, respectively. Considering that many growth media of CPs are single solvent systems, designing certain solvents mixtures and tuning their polarity would bring us new opportunities to achieve morphology and composition control of CPs materials. PMID:23111349

  9. Anion- and Solvent-Induced Assembly and Reversible Structural Transformation of d(10)-Metal Coordination Architectures Containing N-(4-(4-Aminophenyloxy)phenyl)isonicotinamide.

    PubMed

    Tzeng, Biing-Chiau; Hung, Yu-Ching; Lee, Gene-Hsiang

    2016-01-22

    We set out studies on anion- and solvent-induced assembly based on the ligand N-(4-(4-aminophenyloxy)phenyl)isonicotinamide (papoa), which is synthesized to show a bent and flexible backbone. Reactions of papoa with ZnX2 (X=Cl, Br, and I) gave the dinuclear macrocycles ([ZnX2 (papoa)]2 ; X=Cl (1 a), Br (2 a), I (3)), the structure of which was determined by X-ray diffraction. Notably, the less bulky Cl and Br compounds afforded the coordinated imine in acetone (i.e., [ZnX2 (papoi)]2 , papoi=N-(4-(4-(propan-2-ylideneamino)phenoxy)phenyl)isonicotinamide; X=Cl (1 b), Br (2 b)), whereas the iodine one only gave the coordinated amine compound 3 under the same reaction condition. In fact, the coordinated imine can return to the amine analogue upon exposure to air or in DMSO, which has been monitored by (1)H NMR spectroscopy and powder X-ray diffraction. Both the dinuclear [Zn(papoa)(NO3)2]2 (4 a) and the 1D [Zn(papoa)2(NO3)2]n (4 b) were formed from the reaction of Zn(NO3)2 and papoa in mixed solvents with acetone and acetonitrile, respectively. In addition, Cd(ClO4)2 can react with papoa to give the 1D framework {[Cd(papoa)2 (CH3CN)2](ClO4)2}n (5 a) and the 2D framework [Cd(papoa)2 (ClO4)2]n (5 b), depending on the solvent used, that is, MeOH and CH3CN, respectively. Importantly, the 1D framework with axially coordinated CH3 CN molecules and the 2D framework with axially coordinated ClO4(-) ions can be interconverted by heating and grinding in the presence of CH3CN, respectively. Such a reversible structural transformation process was proven by PXRD studies. PMID:26677168

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

    SciTech Connect

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

    2011-12-31

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

  11. Weakly Polar Aprotic Ionic Liquids Acting as Strong Dissociating Solvent: A Typical "Ionic Liquid Effect" Revealed by Accurate Measurement of Absolute pKa of Ylide Precursor Salts.

    PubMed

    Mao, Chong; Wang, Zedong; Wang, Zhen; Ji, Pengju; Cheng, Jin-Pei

    2016-05-01

    Absolute pKas of selected salts with different counter-anions were measured with high precision in four aprotic ionic liquids (AILs), which enables a detailed examination of solvation effect of ILs on salts. Interestingly, the counter-anions of the ylide precursor salts, protic amine, and phenol salts of this study, though differing dramatically in size and electron dispersion, were found to have no effect on the respective pKas of the substrates. This indicates that the ionic species generated upon acidic dissociation of the salts in weakly polar AILs of low dielectric constant (ε: 10-15) are not ion-paired, or in other words, behave like "free ions" as if in strongly dissociating molecular solvents of high polarity (e.g., DMSO). This suggests that the widely assumed ion-pairing phenomenon, an issue of much debate, is not important in the AILs under our experimental conditions, presenting a typical "ionic-liquid effect" on the solvation of charged species in AILs. PMID:27077218

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

    NASA Astrophysics Data System (ADS)

    Hall, Mildred V.

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

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

    PubMed

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

    2015-01-12

    Phosphane and N-heterocyclic carbene ligated gold(I) chlorides can be effectively activated by Na[Me3NB12Cl11] (1) under silver-free conditions. This activation method with a weakly coordinating closo-dodecaborate anion was shown to be suitable for a large variety of reactions known to be catalyzed by homogeneous gold species, ranging from carbocyclizations to heterocyclizations. Additionally, the capability of 1 in a previously unknown conversion of 5-silyloxy-1,6-allenynes was demonstrated. PMID:25394284

  14. A New Family of Anionic Fe(III) Spin Crossover Complexes Featuring a Weak-Field N2 O4 Coordination Octahedron.

    PubMed

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

    2016-01-01

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

  15. 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)

    Rosenthal, Deborah Renee

    2011-12-01

    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.

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

    PubMed

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

    2015-04-21

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

  17. Ag coordination compounds of a bifunctional diaminotriazine-imidazole ligand with various anions and solvents: Synthesis, structures, photoluminescence, and thermal properties

    NASA Astrophysics Data System (ADS)

    Mei, Hong-Xin; Huang, Hua-Qi; Zhang, Ting; Huang, Rong-Bin; Zheng, Lan-Sun

    2016-03-01

    Six coordination compounds of Ag(I) and 2,4-diamino-6-[2-(2-methyl-1-imidazolyl)ethyl]-1,3,5-triazine (L, Ag:L = 1:2) with different anions and solvents, namely, [Ag(L)2]•(NO3)•4(H2O) (1), [Ag(L)2 ] · 1 / 2 (nds) ·(MeOH) ·(H2O) (2, H2nds = 1,5-naphthalenedisulfonic acid), [Ag(L)2 ] · 1 / 2 (nds) ·(MeOH) · 5 / 2 (H2O) (3), [Ag(L)2 ] · 1 / 2 (nds) ·(CH3CN) (4), [Ag(L)2]•(ClO4)•(MeOH)•(H2O) (5), and [Ag(L)2]•(ClO4)•2(H2O) (6), have been synthesized and characterized by elemental analysis, IR, PXRD and X-ray single-crystal diffraction. In these compounds, each Ag(I) ion is ligated by two imidazole nitrogens to form a Ag(L)2 unit. The anions and solvents determine hydrogen-bonding between the DAT groups links the Ag(L)2 units whether to form chains in 1 and 2 or layers in 3-6. In addition, thermogravimetric analysis (TGA) and luminescent properties of these compounds were also investigated.

  18. A series of phenyl sulfonate metal coordination polymers as catalysts for one-pot Biginelli reactions under solvent-free conditions.

    PubMed

    Wang, Jin-Hua; Tang, Gui-Mei; Wang, Yong-Tao; Cui, Yue-Zhi; Wang, Jun-Jie; Ng, Seik Weng

    2015-10-28

    Three new metal coordination polymers, namely, [Co(DPP)2(H2O)2]·(BS)2·2H2O (1), [Co(DPP)2(H2O)2]·(ABS)2·2H2O (2) and [Co(DPP)2(MBS)2] (3) [DPP = 1,3-di(pyridin-4-yl)propane, BS = phenyl sulfonic acid, ABS = p-aminobenzene sulfonic acid, MBS = p-methylbenzene sulfonic acid] were obtained under hydrothermal conditions. Complexes 1-3 were structurally characterized using X-ray single-crystal diffraction, XRD and IR spectroscopy. Both complexes 1 and 2 display a 1D tape structure. Meanwhile, complex 3 exhibits a 2D layer and further stacks via C-Hπ interactions to generate a three-dimensional supramolecular architecture. These three metal coordination polymers have been applied as catalysts for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent-free conditions through the Biginelli reaction. Interestingly, the catalysis products have been obtained in high yields under eco-friendly synthesis conditions. PMID:26399501

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2016-03-10

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    PubMed

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

    2016-04-18

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

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

    PubMed

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

    2015-06-01

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

  6. Weakly coordinating nature of a carborane cage bearing different halogen atoms. Synthesis and structural characterization of icosahedral mixed halocarborane anions, 1-H-CB11Y5X6- (X, Y = Cl, Br, I).

    PubMed

    Tsang, C W; Yang, Q; Sze, E T; Mak, T C; Chan, D T; Xie, Z

    2000-12-11

    Mixed halocarborane anions, 1-H-CB11Y5X6- (X, Y = Cl, Br, I), have been prepared by treatment of [Me3NH][1-H-CB11H5X6] (X = Cl, Br, I) with proper halogenating reagents at 180-220 degrees C in a sealed tube in high yield. These new anions are fully characterized by 1H, 13C, and 11B NMR, IR, and negative-ion MALDI MS spectroscopy. Some are further confirmed by single-crystal X-ray analyses. The weakly coordinating nature of these anions is probed by 29Si chemical shifts of the resulting Pri3Si(1-H-CB11Y5X6) compounds. The results suggest that the coordinating ability of these anions is mainly dependent on the substituents at 7-12 positions (namely, X atoms), and the contribution from the upper belt substituents Y is relatively small. These suggestions are consistent with the results obtained from the structural study of silver salts of mixed halo- and perhalocarborane anions. PMID:11151389

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

    PubMed

    Bhardwaj, Vimal K; Singh, Ajnesh

    2014-10-01

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

  8. Solvent substitution

    SciTech Connect

    Not Available

    1990-01-01

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

  9. 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,...

  10. Weak Deeply Virtual Compton Scattering

    SciTech Connect

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2007-03-01

    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.

  11. Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1957-06-01

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

  12. Solvent-induced and polyether-ligand-induced redox isomerization within an asymmetrically coordinated mixed-valence ion: trans-(py)(NH[sub 3])[sub 4]Ru(4-NCpy)Ru(2,2[prime]-bpy)[sub 2]Cl[sup 4+

    SciTech Connect

    Curtis, J.C.; Massum, M. ); Roberts, J.A.; Blackbourn, R.L.; Dong, Yuhua; Johnson, C.S.; Hupp, J.T. )

    1991-10-02

    Advantage is taken of oxidation-state-dependent ligand (ammine)/solvent interactions to shift redox potentials and effect redox isomerization in the title complex. In poorly basic solvents, the stable isomeric form is trans-(py)(NH[sub 3])[sub 4]Ru[sup II](NCpy)Ru[sup III](bpy)[sub 2]Cl[sup 4+] (py is pyridine; NCpy is 4-cyanopyridine; bpy is 2,2[prime]-bipyridine). In contrast, in stronger Lewis bases or in a mixture of strong and weak bases (dimethyl sulfoxide + nitromethane), the preferred isomer is trans-(py)(NH[sub 3])[sub 4]Ru[sup III](NCpy)Ru[sup II](bpy)Cl[sup 4+]. Evidence for redox isomerization was obtained, in part, from plots of formal potentials versus solvent Lewis basicity. Confirmatory evidence was obtained from a combination of electrochemical reaction entropy and resonance Raman spectroscopic experiments. UV-vis-near-IR absorption experiments, however, were not found to be useful in demonstrating isomerization. In a released series of experiments, redox isomerization was also demonstrated based on ammine binding by either a low molecular weight poly(ethylene glycol) species or by a macrocyclic ligand, dibenzo-36-crown-12. Much smaller molar amounts of either the polymer (substoichiometric) or crown (approximately stoichiometic) are required, in comparison to basic solvent (several-fold excess), in order to induce isomerization in nitromethane as the initial solvent. The possible general utility of the redox isomerization concept in time-resolved intramolecular charge-transfer studies and in optical studies of competitive hole- and electron hole- and electron-transfer pathways is mentioned.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    SciTech Connect

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

    2015-05-01

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

  15. Solvent wash solution

    DOEpatents

    Neace, James C.

    1986-01-01

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

  16. Solvent wash solution

    DOEpatents

    Neace, J.C.

    1984-03-13

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

  17. Solvent-Induced Change of Electronic Spectra and Magnetic Susceptibility of Co(II) Coordination Polymer with 2,4,6-Tris(4-pyridyl)-1,3,5-triazine.

    PubMed

    Polunin, Ruslan A; Burkovskaya, Nataliya P; Satska, Juliya A; Kolotilov, Sergey V; Kiskin, Mikhail A; Aleksandrov, Grigory G; Cador, Olivier; Ouahab, Lahcène; Eremenko, Igor L; Pavlishchuk, Vitaly V

    2015-06-01

    One-dimensional coordination polymer [Co(Piv)2(4-ptz)(C2H5OH)2]n (compound 1, Piv(-) = pivalate, 4-ptz = 2,4,6-tris(4-pyridyl)-1,3,5-triazine) was synthesized by interaction of Co(II) pivalate with 4-ptz. Desolvation of 1 led to formation of [Co(Piv)2(4-ptz)]n (compound 2), which adsorbed N2 and H2 at 78 K as a typical microporous sorbent. In contrast, absorption of methanol and ethanol by 2 at 295 K led to structural transformation probably connected with coordination of these alcohols to Co(II). Formation of 2 from 1 was accompanied by change of color of sample from orange to brown and more than 2-fold decrease of molar magnetic susceptibility (χM) in the temperature range from 2 to 300 K. Resolvation of 2 by ethanol or water resulted in restoration of spectral characteristics and χM values almost to the level of that of 1. χMT versus T curves for 1 and samples, obtained by resolvation of 2 by H2O or C2H5OH, were fitted using a model for Co(II) complex with zero-field splitting of this ion. PMID:25974728

  18. NEPTUNIUM SOLVENT EXTRACTION PROCESS

    DOEpatents

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

    1959-10-01

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

  19. Solvents safety handbook

    SciTech Connect

    De Renzo, D.J.

    1986-01-01

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

  20. Solvent recycle/recovery

    SciTech Connect

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

    1990-09-01

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

  1. Solvents and sustainable chemistry

    PubMed Central

    Welton, Tom

    2015-01-01

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

  2. State Coordination of Higher Education: The Modern Concept.

    ERIC Educational Resources Information Center

    Glenny, Lyman A.

    Coordination of higher education as practiced in three similar organizational forms is assessed: the statewide governing board, the regulatory coordinating board, and the advisory board. Attention is directed to why coordination is important, criticism of coordination, kinds of organizations used, the accomplishments and weaknesses of the…

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

    PubMed

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

    2014-10-11

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

  4. The Lanthanide Contraction beyond Coordination Chemistry.

    PubMed

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

    2016-05-10

    The lanthanide contraction is conceptualized traditionally through coordination chemistry. Here we break this mold in a structural study of lanthanide ions dissolved in an amphiphilic liquid. The lanthanide contraction perturbs the weak interactions between molecular aggregates that drive mesoscale assembly and emergent behavior. The weak interactions correlate with lanthanide ion transport properties, suggesting new strategies for rare-earth separation that exploit forces outside of the coordination sphere. PMID:27060294

  5. Solvent extraction of diatomite

    SciTech Connect

    Williams, W.

    1984-07-24

    There is provided a method of extracting hydrocarbons from a diatomite ore. The particle size of the ore is first reduced to form a processed ore. The processed ore is then mixed with a substantially irregular granular material to form an unstratified ore mixture having increased permeability to an extracting solvent. The unstratified ore mixture is then permeated with an extracting solvent to obtain a hydrocarbon-solvent stream from which hydrocarbons are subsequently separated. The irregular granular material may be sand.

  6. COORDINATED AV.

    ERIC Educational Resources Information Center

    CLEAVES, PAUL C.; AND OTHERS

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

  7. A naphthalimide-based fluorescent sensor for halogenated solvents.

    PubMed

    Dai, Li; Wu, Di; Qiao, Qinglong; Yin, Wenting; Yin, Jun; Xu, Zhaochao

    2016-01-26

    A fluorescent sensor for halogenated solvents termed is reported. shows strong fluorescence in most halogenated solvents (QE > 0.1) but weak fluorescence (QE<0.01) in most non-halogenated solvents. In chlorinated solvents, the fluorescence intensity decreased with the reduction of chlorine content. On the contrary, in brominated solvents the fluorescence intensity increased with the reduction of bromine content. It is worth mentioning that displayed fluorescence emission centered at 520 nm in CCl4 with a quantum yield of 0.607, at 556 nm in CHCl3 with a quantum yield of 0.318, at 584 nm in CH2Cl2 with a quantum yield of 0.128, whereas in CHBr3 was centered at 441 nm with a quantum yield of 0.012. was shown to have the ability to differentiate CCl4, CHCl3, CH2Cl2 and CHBr3 halogenated solvents. PMID:26691881

  8. SOLVENT EXTRACTION OF NEPTUNIUM

    DOEpatents

    Butler, J.P.

    1958-08-12

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

  9. 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...

  10. 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...

  11. Alternative Green Solvents Project

    NASA Technical Reports Server (NTRS)

    Maloney, Phillip R.

    2012-01-01

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

  12. SOLVENT EXTRACTION PROCESS

    DOEpatents

    Jonke, A.A.

    1957-10-01

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

  13. Solvent alternatives guide

    SciTech Connect

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

    1996-06-01

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

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

    PubMed

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

    2014-01-01

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

  15. 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).

  16. 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...

  17. Conformational transitions of a weak polyampholyte

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  18. Weak Gravitational Field and Casimir Energy

    NASA Astrophysics Data System (ADS)

    Tanhayi, M. R.; Pirmoradian, R.

    2016-02-01

    In this paper we consider the effect of a weak gravitation field on the Casimir energy. Under a weak perturbation of a metric, we first obtain the linear energy-momentum tensor of a scalar field in a generic background and then the corrected energy of a scalar filed which satisfies the Dirichlet boundary condition is calculated up to first order of the metric perturbation. We show that our results coincide to the previous related works e.g., the Casimir effect when studied in Fermi coordinates.

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

    DOEpatents

    Nerad, Bruce A.; Krantz, William B.

    1988-01-01

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

  20. SOLVENT EXTRACTION OF RUTHENIUM

    DOEpatents

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

    1959-07-14

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

  1. Supercritical solvent coal extraction

    NASA Technical Reports Server (NTRS)

    Compton, L. E. (Inventor)

    1984-01-01

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

  2. Cleaning without chlorinated solvents

    SciTech Connect

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

    1994-12-31

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

  3. Cleaning without chlorinated solvents

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  4. Partial Coordination Numbers in Binary Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Miracle, Daniel B.; Laws, Kevin; Senkov, Oleg N.; Wilks, Garth B.

    2012-08-01

    A critical analysis of measured partial coordination numbers for binary metallic glasses as a function of composition shows a large scatter of 1.5 but clear trends. The current work uses two topological models to predict the influence of relative atomic size and concentration on partial coordination numbers. The equations for partial coordination numbers derived from these two models can reproduce measured data within experimental scatter, suggesting that chemical effects on local structure, although present, may be relatively small. Insights gained from these models show that structural site-filling rules are different for glasses with solute atoms that are smaller than solvent atoms and for glasses where solute atoms are larger than solvent atoms. Specifically, solutes may occupy both ? and ? intercluster sites when the solute-to-solvent radius ratio R is less than 1.26, but only ? sites can be occupied by solutes when R > 1.26. This distinction gives a simple topological explanation for the observed preference for binary metallic glasses with solutes smaller than solvent atoms. In addition to structure-specific equations, simplified phenomenological equations for partial coordination numbers are given as a convenience.

  5. Dendritic brushes under theta and poor solvent conditions

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    ERIC Educational Resources Information Center

    Dumay, Xavier

    2014-01-01

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

  7. History of Weak Interactions

    DOE R&D Accomplishments Database

    Lee, T. D.

    1970-07-01

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

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

    PubMed Central

    Ortuño, Manuel A

    2013-01-01

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

  9. Halogenated solvent remediation

    DOEpatents

    Sorenson, Kent S.

    2004-08-31

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

  10. Halogenated solvent remediation

    DOEpatents

    Sorenson, Jr., Kent S.

    2008-11-11

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

  11. Safe battery solvents

    DOEpatents

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

    2007-10-23

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

  12. Solvent resistant copolyimide

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

  13. Separation by solvent extraction

    DOEpatents

    Holt, Jr., Charles H.

    1976-04-06

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

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

    PubMed

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

    2009-10-21

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

  15. Weak bond screening system

    NASA Astrophysics Data System (ADS)

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

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

  16. Weak bump quasars

    NASA Astrophysics Data System (ADS)

    Wilkes, B. J.; McDowell, J.

    1994-01-01

    Research into the optical, ultraviolet and infrared continuum emission from quasars and their host galaxies was carried out. The main results were the discovery of quasars with unusually weak infrared emission and the construction of a quantitative estimate of the dispersion in quasar continuum properties. One of the major uncertainties in the measurement of quasar continuum strength is the contribution to the continuum of the quasar host galaxy as a function of wavelength. Continuum templates were constructed for different types of host galaxy and individual estimates made of the decomposed quasar and host continua based on existing observations of the target quasars. The results are that host galaxy contamination is worse than previously suspected, and some apparent weak bump quasars are really normal quasars with strong host galaxies. However, the existence of true weak bump quasars such as PHL 909 was confirmed. The study of the link between the bump strength and other wavebands was continued by comparing with IRAS data. There is evidence that excess far infrared radiation is correlated with weaker ultraviolet bumps. This argues against an orientation effect and implies a probable link with the host galaxy environment, for instance the presence of a luminous starburst. However, the evidence still favors the idea that reddening is not important in those objects with ultraviolet weak bumps. The same work has led to the discovery of a class of infrared weak quasars. Pushing another part of the envelope of quasar continuum parameter space, the IR-weak quasars have implications for understanding the effects of reddening internal to the quasars, the reality of ultraviolet turnovers, and may allow further tests of the Phinney dust model for the IR continuum. They will also be important objects for studying the claimed IR to x-ray continuum correlation.

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

    PubMed

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

    2016-04-01

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

  18. Solvent vapor collector

    DOEpatents

    Ellison, Kenneth; Whike, Alan S.

    1979-01-30

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

  19. ONSITE SOLVENT RECOVERY

    EPA Science Inventory

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

  20. Organic solvent topical report

    SciTech Connect

    COWLEY, W.L.

    1999-05-13

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

  1. Solvent extraction processes compared

    SciTech Connect

    Kogut, K.E.

    1994-04-01

    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.

  2. ENGINEERING BULLETIN: SOLVENT EXTRACTION

    EPA Science Inventory

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

  3. SOLVENT EXTRACTION TREATMENT

    EPA Science Inventory

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

  4. DESIGNING GREENER SOLVENTS

    EPA Science Inventory

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

  5. Organic solvent topical report

    SciTech Connect

    Cowley, W.L.

    1998-04-30

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

  6. Controlling chemical self-assembly by solvent-dependent dynamics.

    PubMed

    Korevaar, Peter A; Schaefer, Charley; de Greef, Tom F A; Meijer, E W

    2012-08-15

    The influence of the ratio between poor and good solvent on the stability and dynamics of supramolecular polymers is studied via a combination of experiments and simulations. Step-wise addition of good solvent to supramolecular polymers assembled via a cooperative (nucleated) growth mechanism results in complete disassembly at a critical good/poor solvent ratio. In contrast, gradual disassembly profiles upon addition of good solvent are observed for isodesmic (non-nucleated) systems. Due to the weak association of good solvent molecules to monomers, the solvent-dependent aggregate stability can be described by a linear free-energy relationship. With respect to dynamics, the depolymerization of π-conjugated oligo(p-phenylene vinylene) (OPV) assemblies in methylcyclohexane (MCH) upon addition of chloroform as a good solvent is shown to proceed with a minimum rate around a critical chloroform/MCH solvent ratio. This minimum disassembly rate bears an intriguing resemblance to phenomena observed in protein unfolding, where minimum rates are observed at the thermodynamic midpoint of a protein denaturation experiment. A kinetic nucleation-elongation model in which the rate constants explicitly depend on the good solvent fraction is developed to rationalize the kinetic traces and further extend the insights by simulation. It is shown that cooperativity, i.e., the nucleation of new aggregates, plays a key role in the minimum polymerization and depolymerization rate at the critical solvent composition. Importantly, this shows that the mixing protocol by which one-dimensional aggregates are prepared via solution-based processing using good/poor solvent mixtures is of major influence on self-assembly dynamics. PMID:22808949

  7. Weak decays at PEP

    SciTech Connect

    Yelton, J.M.

    1984-04-01

    Results are presented on four aspects of weak decays. The MARK II measurement of the tau lifetime, the MARK II measurement of the D/sup 0/ lifetime, the measurement from several experiments of the semi-leptonic branching fractions of hadrons constraining b and c quarks, and lastly the MAC measurement of the B lifetime. 30 references.

  8. In praise of weakness

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    ERIC Educational Resources Information Center

    Willey, Joan D.

    1984-01-01

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

  10. Weak Finsler structures and the Funk weak metric

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Athanase; Troyanov, Marc

    2009-04-01

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

  11. DESIGNING ENVIRONMENTALLY BENIGN SOLVENT SUBSTITUTES

    EPA Science Inventory

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

  12. Solvent substitution for electronic products

    SciTech Connect

    Benkovich, M.K.

    1992-01-01

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

  13. Solvent Immersion Imprint Lithography

    SciTech Connect

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

    2014-06-21

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

  14. Hysteresis in weak ferromagnets

    NASA Astrophysics Data System (ADS)

    Bazaliy, Ya. B.; Tsymbal, L. T.; Kakazei, G. N.; Vasiliev, S. V.

    2011-03-01

    Magnetic hysteresis is studied in the orthoferrites ErFeO3 and TmFeO3 using the single crystal samples of millimeter dimensions. It is shown that in both materials one observes a temperature transition manifesting itself through the temperature hysteresis of the magnetic moment and a peculiar temperature evolution of the field hysteresis loop shapes near this transition. Experiments rule out the hypothesis that the ordering of the orthoferrite's rare earth magnetic moments plays an important role in these phenomena. The hysteresis curves can be explained by a few-domain magnetic state of the samples that results from the weak ferromagnetism of the orthoferrites. The phenomenon is generic for weak ferromagnets with temperature dependent magnetization. A large characteristic magnetic length makes the behavior of the relatively big samples analogous to that observed in the nano-size samples of strong ferromagnets. Supported by NSF DMR-0847159, Ukrainian DFFD F28/456-2009, Portuguese FCT ``Ciencia 2007''.

  15. Weakly supervised glasses removal

    NASA Astrophysics Data System (ADS)

    Wang, Zhicheng; Zhou, Yisu; Wen, Lijie

    2015-03-01

    Glasses removal is an important task on face recognition, in this paper, we provide a weakly supervised method to remove eyeglasses from an input face image automatically. We choose sparse coding as face reconstruction method, and optical flow to find exact shape of glasses. We combine the two processes iteratively to remove glasses more accurately. The experimental results reveal that our method works much better than these algorithms alone, and it can remove various glasses to obtain natural looking glassless facial images.

  16. Composite weak bosons

    SciTech Connect

    Suzuki, M.

    1988-04-01

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

  17. 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 ...

  18. Hazardous solvent substitution

    SciTech Connect

    Twitchell, K.E.

    1995-11-01

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

  19. Solvent dynamical effects on bond-breaking electron transfer reactions

    NASA Astrophysics Data System (ADS)

    Zhu, Jianjun; Spirina, O. B.; Cukier, R. I.

    1994-06-01

    The effects of solvent and intramolecular dynamics on the rates of bond-breaking electron transfer (BBET) reactions is investigated. In the model we adopt, suggested by Saveant [J. Am. Chem. Soc. 109, 6788 (1987)], electron transfer and bond breaking are considered to occur as a concerted process. Thermal equilibrium rate constants kie [i=1(2) denoting the forward (reverse) reaction] are derived and exhibit a characteristic Marcus form, with the reorganization energy equal to the sum of contributions from the solvent, intramolecular vibrational and bond-breaking coordinates. The effect of dynamics on the BBET rate constants is studied by using diffusion-reaction equations. We assume that the intramolecular vibrational coordinate is in equilibrium and the solvent and the bond-breaking coordinates can be out of equilibrium. The survival probabilities are derived analytically with the use of a decoupling approximation. The single exponential decay of the survival probabilities leads to nonthermal-equilibrium rate constants ki that interpolate between the thermal equilibrium kie and diffusion controlled kid rate constants (where motion along the nonequilibrium coordinates control the rate) according to k-1i=k-1ie+k-1id. The diffusion controlled rate constants kid depend on the relaxation times along both the bond-breaking and solvent coordinates. For large activation energies, the fast relaxation will dominate the rate, while for small activation energies, the slow relaxation time will dominate the rate. We also discuss the case of the dynamics along the bond-breaking coordinate being characterized by an energy diffusion process. The rate constant is evaluated for high activation barrier reactions and still has the form given above, with a suitably redefined relaxation time for energy diffusion.

  20. Solvent replacement for green processing.

    PubMed Central

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

    1998-01-01

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

  1. SOLVENT FIRE BY-PRODUCTS

    SciTech Connect

    Walker, D; Samuel Fink, S

    2006-05-22

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

  2. Solvent replacement for green processing.

    PubMed

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

    1998-02-01

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

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

    SciTech Connect

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

    2014-03-01

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

  4. Optimized coordinates in vibrational coupled cluster calculations

    NASA Astrophysics Data System (ADS)

    Thomsen, Bo; Yagi, Kiyoshi; Christiansen, Ove

    2014-04-01

    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. Keeli, 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.

  5. Optimized coordinates in vibrational coupled cluster calculations

    SciTech Connect

    Thomsen, Bo; Christiansen, Ove; Yagi, Kiyoshi

    2014-04-21

    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.

  6. Weakly nonlinear theory of supersonic turbopropeller noise

    NASA Astrophysics Data System (ADS)

    Tam, C. K. W.; Salikuddin, M.

    1984-10-01

    An acoustic and weak shock wave propfan noise theory is developed which accounts for nonlinear propagation effects. The approach is that of a boundary value problem using the equations of motion of an inviscid compressible fluid for the governing equations in a cylindrical coordinate system centered about the propfan axis. A thin airfoil approximation allows setting the boundary conditions on the mean blade surface. The linearized boundary values then correspond to the thickness noise and loading noise, and weakly nonlinear propagation is considered in terms of disturbance velocity changes caused by fluid particle motion and sonic velocity alteration from compression and rarefaction. The three-dimensional shock structure emanating from the blades is generated and includes frequency and spectral data. Nonlinear propagation is demonstrated to be significant in the upstream direction. The model is concluded useful for predicting community and cabin noise levels.

  7. Weak decay of hypernuclei

    SciTech Connect

    Grace, R.

    1983-01-01

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

  8. Weakly broken galileon symmetry

    SciTech Connect

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

    2015-09-01

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

  9. Solvent Fractionation of Lignin

    SciTech Connect

    Chatterjee, Sabornie; Saito, Tomonori

    2014-01-01

    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.

  10. Solvent effects on the resonance Raman and electronic absorption spectra of bacteriochlorophyll a cation radical

    SciTech Connect

    Misono, Yasuhito; Itoh, Koichi; Limanatara, Leenawaty; Koyama, Yasushi

    1996-02-08

    Resonance Raman and electronic absorption spectra of bacteriocholrophyll a cation radical (BChl a{sup .+}) were recorded in 14 different kinds of solvents. The frequency of the ring-breathing Raman band of BChl a{sup .+} was in the region of 1596-1599 cm{sup -1} in solvents forming the pentacoordinated state in neutral bacteriochlorophyll a (BChl a), while it was in the region of 1584-1588 cm{sup -1} in solvents forming the hexacoordinated state. BChl a{sup .+} exhibited a key absorption band in the regions 546-554 and 557-563 nm in the above penta- and hexa-coordinating solvents. Therefore, it has been concluded that the penta- and hexa-coordinated states are retained even after conversion of BChl a into BChl a{sup .+} (one-electron oxidization). Application of this rule to the case of 2-propanol solution showed transformation from the penta- to the hexa-coordinated state upon one-electron oxidation in this particular solution. The coordination states of BChl a{sup .+} could be correlated with the donor number(DN) and the Taft parameters, {Beta} and {pi}{sup *}, of the solvent: The hexacoordinated state was formed in solvents with DN >= 18 or {Beta} > 0.5 showing higher electron donating power, while the pentacoordinated state was formed in solvents with {pi}{sup *} > 0.65 showing higher dielectric stabilization. 27 refs., 8 figs., 3 tabs.

  11. Dynamics of Radical Ion Pairs following Photoinduced Electron Transfer in Solvents with Low and Intermediate Polarities.

    PubMed

    Mentel, Kamila K; Nunes, Rui M D; Serpa, Carlos; Arnaut, Luis G

    2015-06-18

    Fluorescence quenching of p-xylene, naphthalene, or pyrene by fumaronitrile in apolar solvents and in solvents of intermediate polarities leads to weakly fluorescent radical ion pairs. This emission is assigned to ion pairs in close contact on the basis of their solvent polarity dependence, kinetics, and thermodynamics. The temperature-dependence of the intensity and fluorescence emission maxima of ion pairs in methyl acetate reveals that they have decay channels competitive with their thermal equilibration. The results presented in this work are consistent with the direct formation of contact ion pairs in weakly polar solvents and in solvents of intermediate polarities as the result of bimolecular photoinduced electron transfer reactions between aromatic hydrocarbons and nitriles. The implications of these findings in free-energy relationships of electron transfer reactions are discussed. PMID:25588979

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

    PubMed

    Cabot, Rafel; Hunter, Christopher A

    2010-04-21

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

  13. Temperature, pressure and solvent dependence of positronium acceptor reactions

    NASA Astrophysics Data System (ADS)

    Gangopadhyay, Debarshi; Ganguly, Bichitra; Dutta-Roy, Binayak

    2002-07-01

    Positronium (Ps) reaction rates ( κ) with weak Acceptors (Ac) leading to the formation of Ps-Ac complexes show several intriguing features: non-monotonic temperature dependence of κ (departing from the usual Arrhenius paradigm), considerable variability of κ with respect to different solvents, and anomalies in response to external pressure at ambient temperature (large changes of κ in some media and hardly any in others). We explain all these phenomena, introducing the novel concept of a critical surface tension, which unifies observations in diverse non-polar solvents at different temperatures and pressures.

  14. Bimetallic coordination networks based on Al(acacCN)3: a building block between inertness and lability.

    PubMed

    Merkens, Carina; Becker, Nils; Lamberts, Kevin; Englert, Ulli

    2012-07-28

    The Al(III) complex of 3-cyanopentane-2,4-dionate (acacCN) features peripheric nitrile groups which may coordinate to silver cations. As the Al(acacCN)(3) building block ranges between inertness and lability, its reactivity towards Ag(I) salts depends on the solvent and the weakly or non-coordinating counter anions; an impressive range of different extended structures has been encountered. With AgPF(6), the original building block is retained and hexafluorophosphate remains uncoordinated. A highly symmetric 3D crystalline solid forms in the presence of trichloromethane, and with benzene a tetrasolvate with large solvent-filled voids is obtained. Two different classes of reaction products with silver triflate have been observed. In addition to networks incorporating Al(acacCN)(3), partial solvolysis may lead to a dinuclear methoxide-bridged derivative. The resulting Al(2)(μ-OMe)(2) core may be perceived as a four-connected node in a self-interpenetrating 3D network. Earlier studies reported transmetalation for the reaction of Al(acacCN)(3) with AgNO(3) and we find the same reactivity for silver tetrafluoroborate. Full degradation of the Al(III) building block with formation of [Ag(acacCN)] is observed. PMID:22669470

  15. Weakly relativistic plasma expansion

    SciTech Connect

    Fermous, Rachid Djebli, Mourad

    2015-04-15

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

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

    SciTech Connect

    Delmau, Laetitia Helene; Moyer, Bruce A

    2012-12-01

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

  17. Carbon-13 nuclear magnetic resonance spectra of potassium (ethylenediaminetetraacetato)cobaltate(III) in organic solvents

    SciTech Connect

    Taura, Toshiaki

    1988-08-10

    The carbon-13 NMR spectra of the (Co(edta))/sup /minus// (edta = ethylenediaminetetraacetate) anion were observed in water and a variety of organic solvents: ethylene glycol, methanol, formamide, ethanol, 2-propanol, chloroform, dichloromethane, dimethyl sulfoxide, acetonitrile, dimethylformamide, benzonitrile, and dimethylacetamide. The spectra in organic solvents were obtained after 1-2-h accumulations for the concentrated solutions (0.5 M) of the complex anion that were prepared by the addition of a macrobicyclic polyether, cryptand 222, to the solvents. The /sup 13/C NMR signals of the coordinated carboxylates are markedly shifted downfield in protic solvents in comparison with aprotic solvent (the greatest difference in chemical shift is 3.9 ppm), while the NMR chemical shifts of methylene carbons of ligands are not significantly influenced by solvent molecules. The magnitudes (/sigma/ values) of this downfield shift of the coordinated carboxylate /sup 13/C signals are found to be correlated linearly with the electrophilic ability of the solvent molecules. This finding leads to the conclusion that the (Co(edta))/sup /minus// anion interacts with solvent molecules through the hydrogen-bonding between solvent hydrogens and carboxyl oxygens of the complex anion. 10 references, 4 figures, 1 table.

  18. Microphase Separation Transition for Polyelectrolyte Gels in Poor Solvents

    NASA Astrophysics Data System (ADS)

    Zeldovich, Konstantin B.; Dormidontova, Elena E.; Khokhlov, Alexei R.; Vilgis, Thomas A.

    1997-04-01

    The microphase separation transition in the weakly charged polyelectrolyte gels immersed in poor solvent and undergoing collapse transition is studied in the weak crystallization approximation. The chain connectivity in the gel is taken into account via introducing “polarization" term first proposed by de Gennes. It is shown that in this case the gel can undergo multistage jump like collapse where the intermediate states can have regular microstructures of different symmetry. The availability of numerous metastable states in the collapse region may lead to the pronounced hysteresis effects. These results are compared with some of the recent experimental findings.

  19. Femtosecond transient dichroism/birefringence studies of solute- solvent friction and solvent dynamics

    SciTech Connect

    Chang, Y.J.; Castner, E.W. Jr.; Konitsky, W.; Waldeck, D.H.

    1994-02-01

    Ultrafast, heterodyne, polarization spectroscopies are used to measure solute-solvent frictional coupling and characterize the neat solvent`s relaxation dynamics on femtosecond and picosecond timescales.

  20. Movement and Coordination

    MedlinePlus

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

  1. SOLVENT EXTRACTION OF URANIUM VALUES

    DOEpatents

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

    1959-02-01

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

  2. Chemical reactivity: Inverse solvent design

    NASA Astrophysics Data System (ADS)

    Truhlar, Donald G.

    2013-11-01

    Choosing a solvent for a particular reaction is often a matter of personal preference or the result of limited screening. Now, a computational method allows identification of a solvent that will enhance the kinetics of a reaction prior to running a wet experiment.

  3. Supercritical multicomponent solvent coal extraction

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

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

    PubMed

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

    2015-11-10

    Evaluation of solvation (binding) free energies with implicit solvent models in different dielectric environments for biological simulations as well as high throughput ligand screening remain challenging endeavors. In order to address how well implicit solvent models approximate explicit ones we examined four generalized Born models (GB(Still), GB(HCT), GB(OBC)I, and GB(OBC)II) for determining the dimerization free energy (ΔG(0)) of β-cyclodextrin monomers in 17 implicit solvents with dielectric constants (D) ranging from 5 to 80 and compared the results to previous free energy calculations with explicit solvents ( Zhang et al. J. Phys. Chem. B 2012 , 116 , 12684 - 12693 ). The comparison indicates that neglecting the environmental dependence of Born radii appears acceptable for such calculations involving cyclodextrin and that the GB(Still) and GB(OBC)I models yield a reasonable estimation of ΔG(0), although the details of binding are quite different from explicit solvents. Large discrepancies between implicit and explicit solvent models occur in high-dielectric media with strong hydrogen bond (HB) interruption properties. ΔG(0) with the GB models is shown to correlate strongly to 2(D-1)/(2D+1) (R(2) ∼ 0.90) in line with the Onsager reaction field ( Onsager J. Am. Chem. Soc. 1936 , 58 , 1486 - 1493 ) but to be very sensitive to D (D < 10) as well. Both high-dielectric environments where hydrogen bonds are of interest and low-dielectric media such as protein binding pockets and membrane interiors therefore need to be considered with caution in GB-based calculations. Finally, a literature analysis of Gibbs energy of solvation of small molecules in organic liquids shows that the Onsager relation does not hold for real molecules since the correlation between ΔG(0) and 2(D-1)/(2D+1) is low for most solutes. Interestingly, explicit solvent calculations of the solvation free energy ( Zhang et al. J. Chem. Inf. Model . 2015 , 55 , 1192 - 1201 ) reproduce the weak experimental correlations with 2(D-1)/(2D+1) very well. PMID:26574308

  5. The theory and effect of solvent environment on biomolecules

    NASA Astrophysics Data System (ADS)

    Schnieders, Michael J.

    This dissertation describes the theory and effect of solvent environment on biomolecules using a computational model known as a force field. Force fields are based on formulating an efficient, empirical function of atomic coordinates designed to reproduce the potential energy surface predicted by the more rigorous, but also intractably expensive Schrodinger equation. In particular, this work is novel due to use of an Atomic Multipole Optimized Energetics for Biomolecular Applications (AMOEBA) force field that represents charge density using polarizable atomic multipoles. Polarizable Multipole Poisson-Boltzmann (PMPB) and generalized Kirkwood (GK) continuum electrostatics models are described that interact self-consistently with AMOEBA biomolecules. In conjunction with a novel apolar estimator, the PMPB and GK models are used to construct two implicit solvents for solutes represented by the AMOEBA force field. The effect of solvent environment on the electrostatic moments of a large set of folded proteins is examined.

  6. Processing Coordination Ambiguity

    ERIC Educational Resources Information Center

    Engelhardt, Paul E.; Ferreira, Fernanda

    2010-01-01

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

  7. Solvent degradation products in nuclear fuel processing solvents

    SciTech Connect

    Shook, H.E. Jr.

    1988-06-01

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

  8. 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...

  9. 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...

  10. Solvent effect on palladium-catalyzed cross-coupling reactions and implications on the active catalytic species.

    PubMed

    Proutiere, Fabien; Schoenebeck, Franziska

    2011-08-22

    Suzuki coupling of the bifunctional substrate 1 using [Pd(2)(dba)(3)]/PtBu(3) gives selectivity for C-Cl in nonpolar solvents but for C-OTf in polar solvents. The results of computational and experimental studies suggest that the catalytically active species in polar solvents under conditions employing coordinating additives is inconsistent with monoligated [Pd(PtBu(3))]. Instead, the data are consistent with an anionic palladium complex as the active species. PMID:21751309

  11. Cesium Concentration in MCU Solvent

    SciTech Connect

    Walker, D

    2006-01-18

    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).

  12. Weak interactions and Eotvos experiments

    NASA Technical Reports Server (NTRS)

    Haugan, M. P.; Will, C. M.

    1976-01-01

    A current-current model for weak interactions is used to show that the weak-interaction contribution to the ground-state energies of typical nuclei is about one part in 100 million of their rest masses. By comparing this contribution with the results of recent versions of the Eotvos experiments, it is concluded that weak-interaction energies obey the principle of equivalence to better than one part in 100, thus refuting claims that those experiments did not test weak-interaction effects.

  13. Movement Coordination during Conversation

    PubMed Central

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

    2014-01-01

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

  14. Occupational neurotoxicology of organic solvents and solvent mixtures

    SciTech Connect

    Triebig, G. )

    1989-11-01

    The results of two field studies in painters and spray painters, the outcomes of examinations of workers with suspected work-related disease due to solvents, as well as data from an evaluation of an epidemiologic study in painters with confirmed occupational disease, are presented and discussed. The results of these studies and the experiences in occupational medicine in the Federal Republic of Germany do not support the assumption of high neurotoxic risks in solvent-exposed workers, which can be postulated from various epidemiologic studies from Scandinavian countries. Several factors may explain the different conclusions: (1) lower solvent exposures of German painters in the past decades; (2) false positive diagnosis of a toxic encephalopathy; (3) aetiological misclassification; (4) differences in legislation relevant for the acknowledgement of occupational diseases. In conclusion, there is a need for further well-designed epidemiologic studies in occupationally solvent-exposed workers. Suggestions regarding assessment of exposure and neurobehavioral tests are given.

  15. EXPERIENCES IN DESIGNING SOLVENTS FOR THE ENVIRONMENT

    EPA Science Inventory

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

  16. Swelling of lignites in organic solvents

    SciTech Connect

    R.G. Makitra; D.V. Bryk

    2008-10-15

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

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

    PubMed Central

    Al-Qunaibit, M. H.

    2009-01-01

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

  18. Solvent Polarity Tunes the Barrier Height for Twisted Intramolecular Charge Transfer in N-Pyrrolobenzonitrile (PBN).

    PubMed

    Bohnwagner, Mercedes V; Burghardt, Irene; Dreuw, Andreas

    2016-01-14

    4-(1H-pyrrol-1-yl)benzonitrile (PBN) is a typical intramolecular donor-acceptor (D/A) molecule that shows dual fluorescence in weakly polar environments. In this work the underlying photochemical reaction mechanism is investigated theoretically by using high-level ab initio methods including the recently implemented third order algebraic diagrammatic construction of the polarization propagator (ADC(3)). Solvation effects have been considered by using different sophisticated continuum model approaches. Our results conclusively explain all available experimental findings including the effects of excitation wavelength, temperature and solvent polarity. After photoexcitation in gas phase to the bright 2A (S2, ππ*) state, PBN relaxes on the 2A state surface until a conical intersection with the energetically close-lying dark 1B (S1, LE) state is reached. After passing this conical intersection PBN further relaxes on the LE state surface toward a minimum from which emission can occur. In polar environments this picture changes. Then the polar 2B (S3, CT) state is stabilized and an energy barrier along the twisting coordinate vanishes. As a consequence population of the twisted 2B state minimum becomes the dominating decay channel and red-shifted fluorescence occurs. PMID:26639634

  19. 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...

  20. 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 ...

  1. 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...

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

    PubMed

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

    2015-05-01

    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

  3. Solvent choices and sustainable chemistry.

    PubMed

    Kemeling, Guido M

    2012-12-01

    No easy solutions: Choosing a solvent for a certain reaction is not easy, and involves sustainability on many levels. The choice can be motivated by wanting to reduce or avoid wastes, reduce resource use, lower risks to humans and the environment, lessen energy use, or other ways of avoiding liabilities and costs. ChemSusChem wishes to promote thoughtful discussions on solvent use, and outlines in this Editorial basic guidelines for authors and referees. PMID:23208851

  4. Explicitly computing geodetic coordinates from Cartesian coordinates

    NASA Astrophysics Data System (ADS)

    Zeng, Huaien

    2013-04-01

    This paper presents a new form of quartic equation based on Lagrange's extremum law and a Groebner basis under the constraint that the geodetic height is the shortest distance between a given point and the reference ellipsoid. A very explicit and concise formulae of the quartic equation by Ferrari's line is found, which avoids the need of a good starting guess for iterative methods. A new explicit algorithm is then proposed to compute geodetic coordinates from Cartesian coordinates. The convergence region of the algorithm is investigated and the corresponding correct solution is given. Lastly, the algorithm is validated with numerical experiments.

  5. Water as a solvent for life

    NASA Astrophysics Data System (ADS)

    Pohorille, Andrew

    2015-08-01

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

  6. Adapted harmonic coordinates

    SciTech Connect

    Bel, L.; Coll, B. )

    1993-06-01

    The authors obtain the necessary and sufficient conditions that a timelike congruence has to satisfy to admit three independent adapted harmonic coordinates of space, proving in the process that if it does then these coordinates are unique up to a linear transformation with constant coefficients. As a particular example it is proven that irrotational pure Born (i.e. not Killing) congruences never admit a system of adapted harmonic coordinates of space. 8 refs.

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

    SciTech Connect

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

    2014-01-21

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    2013-08-01

    Definite noun phrases typically refer to entities that are uniquely identifiable in the speaker and addressee's common ground. Some definite noun phrases (e.g., the hospital in Mary had to go the hospital and John did too) seem to violate this uniqueness constraint. We report six experiments that were motivated by the hypothesis that these "weak definite" interpretations arise in "incorporated" constructions. Experiments 1-3 compared nouns that seem to allow for a weak definite interpretation (e.g., hospital, bank, bus, radio) with those that do not (e.g., farm, concert, car, book). Experiments 1 and 2 used an instruction-following task and picture-judgment task, respectively, to demonstrate that a weak definite need not uniquely refer. In Experiment 3 participants imagined scenarios described by sentences such as The Federal Express driver had to go to the hospital/farm. 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

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  12. Conserve Water: A Method for the Analysis of Solvent in Molecular Dynamics.

    PubMed

    Harrigan, Matthew P; Shukla, Diwakar; Pande, Vijay S

    2015-03-10

    Molecular dynamics with explicit solvent is favored for its ability to more correctly simulate aqueous biological processes and has become routine thanks to increasingly powerful computational resources. However, analysis techniques including Markov state models (MSMs) ignore solvent atoms and focus solely on solute coordinates despite solvent being implicated in myriad biological phenomena. We present a unified framework called "solvent-shells featurization" for including solvent degrees of freedom in analysis and show that this method produces better models. We apply this method to simulations of dewetting in the two-domain protein BphC to generate a predictive MSM and identify functional water molecules. Furthermore, the proposed methodology could be easily extended for building MSMs of any systems with indistinguishable components. PMID:26579759

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

    PubMed

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

    2015-02-16

    Room temperature ionic liquids (RTILs) represent a recent new class of solvents applied in liquid/liquid extraction based nuclear fuel reprocessing, whereas the related coordination chemistry and detailed extraction processes are still not well understood and remain of deep fundamental interest. The work herein provides a new insight of coordination and extraction of uranium(VI) with N-donating ligands, e.g., N,N'-diethyl-N,N'-ditolyldipicolinamide (EtpTDPA), in commonly used RTILs. Exploration of the extraction mechanism, speciation analyses of the extracted U(VI), and crystallographic studies of the interactions of EtpTDPA with U(VI) were performed, including the first structurally characterized UO2(EtpTDPA)2(NTf2) and UO2(EtpTDPA)2(PF6)2 compounds and a first case of crystallographic differentiation between the extracted U(VI) complexes in RTILs and in molecular solvents. It was found that in RTILs two EtpTDPA molecules coordinate with one U(VI) ion through the carbonyl and pyridine nitrogen moieties, while NTf2(-) and PF6(-) act as counterions. The absence of NO3(-) in the complexes is coincident with a cation-exchange extraction. In contrast, both the extracted species and extraction mechanisms are greatly different in dichloromethane, in which UO2(2+) coordinates in a neutral complex form with one EtpTDPA molecule and two NO3(-) cations. In addition, the complex formation in RTILs is independent of the cation exchange since incorporating UO2(NO3)2, EtpTDPA, and LiNTf2 or KPF6 in a solution also produces the same complex as that in RTILs, revealing the important roles of weakly coordinating anions on the coordination chemistry between U(VI) and EtpTDPA. These findings suggest that cation-exchange extraction mode for ILs-based extraction system probably originates from the supply of weakly coordinating anions from RTILs. Thus the coordination of uranium(VI) with extractants as well as the cation-exchange extraction mode may be potentially changed by varying the counterions of uranyl or introducing extra anions. PMID:25629464

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  15. Coal liquefaction with supercritical solvents

    SciTech Connect

    Deshpande, G.V.

    1986-01-01

    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.

  16. Polymer adsorption in a poor solvent

    NASA Astrophysics Data System (ADS)

    Johner, A.; Joanny, J. F.

    1991-02-01

    We discuss polymer adsorption in a poor solvent. For a single chain we find a wetting transition on an attractive wall when the thermal correlation lenght xi is of the order of the adsorption lenght D. If D is larger than xi, for weak adsorption, the polymer chain partially wets the solid surface in the same way as a small liquid drop ; if D is smaller than xi, strong adsorption, the chain forms a flat pancake of thickness D. The adsorption of a polymer solution in a poor solvent is considered only when the chains wet the surface. At very low bulk concentration the adsorbed chains form a two dimensional dilute polymer solution which is either in a poor solvent or in a good solvent depending on the value of the attractive excluded volume. When this two dimensional solution is in a poor solvent it undergoes a first order demixing transition analogous to the so-called prewetting transition. At a higher bulk concentration the surface layer becomes continuous, its thickness grows and diverges when the bulk concentration reaches the coexistence curve. We also study the wetting transition of the polymer solution. These results can be applied to diblock copolymer adsorption in a selective solvent. The prewetting transition can also exist in this case if the soluble block is not too large. Nous étudions l'adsorption de polymères en mauvais solvant. Dans le cas d'une chaîne isolée au contact d'une paroi attractive nous obtenons une transition de mouillage lorsque la longueur de corrélation thermique xi est du même ordre de grandeur que la longueur d'extrapolation D qui caractérise l'adsorption. Si D est plus grand que xi, cas d'adsorption faible, la chaîne polymère mouille partiellement la surface comme le ferait une gouttelette de liquide, lorsque D est plus petit que xi, cas de l'adsorption forte, la chaîne forme une galette d'épaisseur D. L'adsorption d'une solution de polymère en mauvais solvant est envisagée uniquement lorsque le polymère mouille la paroi. Aux très faibles concentrations volumiques les chaînes adsorbées constituent une solution diluée à deux dimensions, le polymère est alors en mauvais ou en bon solvant suivant la valeur de l'interaction attractive entre monomères. Lorsque la solution à deux dimensions est en mauvais solvant elle présente une transition de démixtion du premier ordre analogue à la transition de prémouillage. À des concentrations plus élevées, la couche adsorbée devient continue, son épaisseur augmente et présente une divergence logarithmique quand la concentration volumique atteint la coexistence. Nous étudions également la transition de mouillage de la solution de polymères. Les résultats peuvent être appliqués à l'adsorption de copolymères biséquencés en solvant sélectif. La transition de prémouillage peut également exister si la masse moléculaire des séquences solubles n'est pas trop élevée.

  17. Weak interactions and presupernova evolution

    SciTech Connect

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

    1991-02-19

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

  18. Quasi-Suslin weak duals

    NASA Astrophysics Data System (ADS)

    Ferrando, J. C.; Kakol, J.; López Pellicer, M.; Saxon, S. A.

    2008-03-01

    Cascales, Kakol, and Saxon (CKS) ushered Kaplansky and Valdivia into the grand setting of Cascales/Orihuela spaces E by proving: (K) If E is countably tight, then so is the weak space (E,[sigma](E,E')), and (V) (E,[sigma](E,E')) is countably tight iff weak dual (E',[sigma](E',E)) is K-analytic. The ensuing flow of quasi-Suslin weak duals that are not K-analytic, a la Valdivia's example, continues here, where we argue that locally convex spaces E with quasi-Suslin weak duals are (K, V)'s best setting: largest by far, optimal vis-a-vis Valdivia. The vaunted CKS setting proves not larger, in fact, than Kaplansky's. We refine and exploit the quasi-LB strong dual interplay.

  19. Team coordination dynamics.

    PubMed

    Gorman, Jamie C; Amazeen, Polemnia G; Cooke, Nancy J

    2010-07-01

    Team coordination consists of both the dynamics of team member interaction and the environmental dynamics to which a team is subjected. Focusing on dynamics, an approach is developed that contrasts with traditional aggregate-static concepts of team coordination as characterized by the shared mental model approach. A team coordination order parameter was developed to capture momentary fluctuations in coordination. Team coordination was observed in three-person uninhabited air vehicle teams across two experimental sessions. The dynamics of the order parameter were observed under changes of a team familiarity control parameter. Team members returned for the second session to either the same (Intact) or different (Mixed) team. 'Roadblock' perturbations, or novel changes in the task environment, were introduced in order to probe the stability of team coordination. Nonlinear dynamic methods revealed differences that a traditional approach did not: Intact and Mixed team coordination dynamics looked very different; Mixed teams were more stable than Intact teams and explored the space of solutions without the need for correction. Stability was positively correlated with the number of roadblock perturbations that were overcome successfully. The novel and non-intuitive contribution of a dynamical analysis was that Mixed teams, who did not have a long history working together, were more adaptive. Team coordination dynamics carries new implications for traditional problems such as training adaptive teams. PMID:20587302

  20. IVS Technology Coordinator Report

    NASA Technical Reports Server (NTRS)

    Whitney, Alan

    2013-01-01

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

  1. Social Postural Coordination

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  2. Coal liquefaction process with enhanced process solvent

    DOEpatents

    Givens, Edwin N.; Kang, Dohee

    1984-01-01

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

  3. On Reaction Coordinate Optimality.

    PubMed

    Krivov, Sergei V

    2013-01-01

    The following question is addressed: how to establish that a constructed reaction coordinate is optimal, i.e., that it provides an accurate description of dynamics. It is shown that the reaction coordinate is optimal if its cut free energy profile, determined using length-weighted transitions, is constant, i.e., it is position and sampling interval independent. The observation leads to a number of interesting results. In particular, the equilibrium flux between two boundary states can be computed exactly as diffusion on a free energy profile associated with the coordinate. The mean square displacement, for the trajectory projected onto the coordinate, grows linear with time. That for the same trajectory projected onto a suboptimal coordinate grows slower than linear with time. The results are illustrated on a number of model systems, Sierpinski gasket, FIP35 protein, and beta3s peptide. PMID:26589017

  4. Propagation of weak shock waves - Shock focusing and shock reflection

    NASA Astrophysics Data System (ADS)

    Obermeier, F.

    1989-08-01

    A modified version of the method of strained coordinates is introduced to permit the solution of nonlinear, hyperbolic wave equations to be reduced to the solution of linear wave equations. The method is then applied to the analytical description of the propagation of weak shock waves and, in particular, to shock focusing and unsteady shock reflection. The transition from regular reflection to Mach reflection, which has not yet been solved satisfactorily in the literature (von Neumann paradox), is of particular interest.

  5. Entanglement-assisted weak measurement

    NASA Astrophysics Data System (ADS)

    Pang, Shengshi; Dressel, Justin; Brun, Todd A.

    2015-03-01

    Postselected weak measurement with a large measurement can amplify small coupling parameters. However, a major shortcoming is that the postselection probability is usually very low when the amplification is large, which means an enormous amount of resources is necessary. So, how to increase the postselection probability is an important problem in practical application of weak measurement. In this work, we study the optimization of weak measurement and propose an entanglement-assisted protocol for it. We start from maximizing the postselection probability with a given weak value. The result shows the maximum postselection probability is proportional to the variance of the observable under the initial state of the system. As is know that the variance has different scaling under entangled or uncorrelated states, it inspired us to show using entanglement in the initial state of the system can increase the postselection efficiency beyond that with sequential use of systems. With this result, we further find the Fisher information of weak measurement can approximately reach the Heisenberg limit with the assistance of entanglement. Finally, we give simple quantum circuits for the implementation of this protocol with qubits, including initialization, weak interaction and postselection. This research was partially supported by the ARO MURI Grant No. W911NF-11-1- 0268. S. P. and T. A. B. also acknowledge the support from NSF Grant No. CCF-0829870, while J. D. acknowledges support from IARPA/ARO Grant No. W91NF-10-1-0334.

  6. Method of treating radioactively contaminated solvent waste

    SciTech Connect

    Jablonski, W.; Mallek, H.; Plum, W.

    1981-07-07

    A method of and apparatus for treating radioactively contaminated solvent waste are claimed. The solvent waste is supplied to material such as peat, vermiculite, diaton, etc. This material effects the distribution or dispersion of the solvent and absorbs the foreign substances found in the solvent waste. Air or an inert gas flows through the material in order to pick up the solvent portions which are volatile as a consequence of their vapor pressure. The thus formed gas mixture, which includes air or inert gas and solvent portions, is purified in a known manner by thermal, electrical, or catalytic combustion of the solvent portions.

  7. Implicit solvent models in VASP

    NASA Astrophysics Data System (ADS)

    Mathew, Kiran; Hennig, Richard

    2015-03-01

    Solid-liquid interfaces are at the heart of many modern-day technologies and presents challenge for materials simulation methods. A realistic first-principles computational study of such systems entails the inclusion of solvent effects. In our previous work, employing a linear implicit solvent model, we have demonstrated the importance of the inclusion of solvent effects on the calucaltions of reaction energy barriers and surface enegies of semiconductor nanocrystals. In this work we propose to extend the implicit solvent model to incorporate the effects of the ions in the solvent and also to include the effects of dilectric saturation phenomenon. A solvation model that includes the effects of ionic solution at a first principle level, takes us one step closer to a more realistic simulation of an electrochemical interface. Incorporating the dielectric saturation effects futher advance the capabilities of the state of the art DFT tools to study the Solid Electrolyte Interface(SEI) films formed on highly ionic surfaces such as Lithium halides.

  8. Dielectric anisotropy in polar solvents under external fields

    NASA Astrophysics Data System (ADS)

    Buyukdagli, Sahin

    2015-08-01

    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 {{\\varepsilon}w}≈ 77 , 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.

  9. Solvent-regenerated activated carbon

    SciTech Connect

    McLaughlin, H. )

    1988-07-01

    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.

  10. Solvent sensitive polymer composite structures

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  11. Solvent reorganization of electron transitions in viscous solvents

    SciTech Connect

    Ghorai, Pradip K.; Matyushov, Dmitry V.

    2006-04-14

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

  12. Exxon donor solvent liquefaction process

    NASA Astrophysics Data System (ADS)

    Neavel, R. C.

    1981-03-01

    The Exxon donor solvent (EDS) coal liquefaction system is a direct liquefaction procedure. Coal is chemically reacted and dissolved in a recycle solvent that is hydrogenated between passes to the liquefaction reactor. More than 2.6 barrels of a synthetic crude boiling below 1000 F are produced per ton of dry, high volatile coal feed. Other ranks of coal can be effectively liquefied. The process development has proceeded to a 250 ton/day pilot plant stage that went into operation in June 1980. The presentation addresses the chemical reactions and process conditions that result in ease of operability and flexibility of the EDS process.

  13. Noncommutativity in weakly curved background by canonical methods

    SciTech Connect

    Davidovic, Lj.; Sazdovic, B.

    2011-03-15

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

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

    PubMed

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

    2015-12-01

    We present a protocol to estimate the solvent-induced broadening of electronic spectra based on a model that explicitly takes into account the environment embedding the solute. Starting from a classical approximation of the solvent contribution to the spectrum, the broadening arises from the spread of the excitation energies due to the fluctuation of the solvent coordinates, and it is represented as a Gaussian line shape that convolutes the vibronic spectrum of the solute. The latter is computed in harmonic approximation at room temperature with a time-dependent approach. The proposed protocol for the computation of spectral broadening exploits molecular dynamics (MD) simulations performed on the solute-solvent system, keeping the solute degrees of freedom frozen, followed by the computation of the excitation properties with a quantum mechanics/molecular mechanics (QM/MM) approach. The factors that might influence each step of the protocol are analyzed in detail, including the selection of the empirical force field (FF) adopted in the MD simulations and the QM/MM partition of the system to compute the excitation energies. The procedure is applied to a family of coumarin dyes, and the results are compared with experiments and with the predictions of a very recent work (Cerezo et al., Phys. Chem. Chem. Phys. 2015, 17, 11401-11411), where an implicit model was adopted for the solvent. The final spectra of the considered coumarins were obtained without including ad hoc phenomenological parameters and indicate that the broadenings computed with explicit and implicit models both follow the experimental trend, increasing as the polarity change from the initial to the final state increases. More in detail, the implicit model provides larger estimations of the broadening that are closer to the experimental evidence, while explicit models appear to better capture relative differences arising from different solvents or different solutes. Possible inaccuracies of the adopted FF that may lead to the observed underestimation are analyzed in detail. PMID:26605552

  15. Compass Coordinate System

    NASA Astrophysics Data System (ADS)

    Wei, Ziqing; Liu, Guangming; Wu, Fumei

    2013-04-01

    This presentation addresses the definition and realization of the Compass Coordinate System, which is utilized by the BeiDou/Compass satellite navigation system. The definition follows the criteria described by the IERS Technical Note No.21. The reference ellipsoid used is the GRS80 ellipsoid except that the IERS recommended value of 3986004.418´108m3s-2 is adopted for the Earth's gravitational constant. The realization has been done in such a way that the system is closely aligned to the ITRF 2008. The relationship between the Compass Coordinate System and the China Geodetic Coordinate System 2000 (CGCS 2000) is also outlined in the presentation.

  16. Solvent Influences on the Molecular Aggregation of Magnesium Aryloxides

    SciTech Connect

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

    2000-07-14

    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.

  17. Quantum discord with weak measurements

    SciTech Connect

    Singh, Uttam Pati, Arun Kumar

    2014-04-15

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

  18. Unusual two-dimensional sheet structure of the solvent-free cesium aryloxide complex CsO-2,6-i-Pr{sub 2}C{sub 6}H{sub 3}

    SciTech Connect

    Clark, D.L.; Click, D.R.; Hollis, R.V.; Scott, B.L.; Watkin, J.G.

    1998-10-19

    During recent investigations into the structure and reactivity of lanthanide aryloxide derivatives, the authors have isolated a number of salt or ate complexes of the stoichiometry M{prime}[Ln(OAr){sub 4}] (M{prime} = K{sup 7}, Cs{sup 8}) and Cs{sub 2}[La(OAr){sub 5}]{sup 9} (Ar = 2,6-i-Pr{sub 2}C{sub 6}H{sub 3}) in which the coordination sphere of the alkali metal cations consists exclusively of multihapto {eta}-arene interactions with aryloxide ligands from adjacent [Ln(OAr){sub 4}]{sup {minus}} or [Ln(OAr){sub 5}]2{sup 2{minus}} units. Following preparation and utilization of the parent alkali metal aryloxide complex Cs(O-2,6-i-Pr{sub 2}C{sub 6}H{sub 3}) during the synthesis of the lanthanum salts, the authors became aware of the dearth of structural data concerning heavy alkali metal aryloxide species. Although many complexes of both the lighter and heavier alkali metal aryloxides have been structurally characterized in which a crown ether is employed to encapsulate the cation, very few solvent-ligated or solvent-free aryloxide salts containing sodium, potassium, rubidium, or cesium have been subjected to X-ray diffraction studies. In the case of cesium, the authors have found only one example of a structurally characterized solvent-free aryloxide complex, namely cesium picrate Cs[O-2,4,6-(NO{sub 2}){sub 3}C{sub 6}H{sub 2}], which has been subjected to X-ray diffraction studies by two independent groups. In addition, very recent high-resolution powder X-ray diffraction data for cesium phenoxide (CsOPh) revealed a chain structure with both six-coordinate and three-coordinate metal ions and a very weak interaction between the cesium cation and an adjacent arene ring. Here, the authors report upon the unusual two-dimensional infinite-sheet structure of the solvent-free cesium aryloxide complex Cs(O-2,6-i-Pr{sub 2}C{sub 6}H{sub 3}). To the best of their knowledge, this work represents the first structural characterization of an alkyl-substituted solvent-free aryloxide complex of the heavier alkali metals.

  19. Theoretical study of chlorophyll a hydrates formation in aqueous organic solvents.

    PubMed

    Ben Fredj, Arij; Ruiz-López, Manuel F

    2010-01-14

    A theoretical analysis of chlorophyll a (Chla) hydration processes in aqueous organic solvents has been carried out by means of quantum chemistry calculations. A detailed knowledge of the thermodynamics of these processes is fundamental in order to better understand the organization of chlorophyll molecules in vivo, specifically the structure of chlorophyll pairs in photosystems I and II. In the present work, we assumed a Chla model in which the phytyl chain is replaced by a methyl group. Calculations were performed at the B3LYP/6-31G(d) level corrected for basis set superposition errors and dispersion interaction energy. This computational scheme was previously shown to provide data close to MP2/6-311++(2d,2p) results. Solvents effects were taken into account using either continuum (for nonpolar solvents) or discrete-continuum (for polar coordinating solvents) methods. In the latter case, we first examined the structure of Chla in rigorously dry solutions. Two types of solvents were characterized according to Mg-atom coordination: In type I solvents (acetone, acetonitrile, DMSO), Mg exhibits five-coordination, whereas in type II solvents (THF, pyridine), Mg exhibits six-coordination. Hydration processes are quite dependent on solvent nature. In nonpolar or low-polarity solvents such as cyclohexane or chloroform, hydration is always exothermic and exergonic, despite a large entropy term that strongly opposes hydration. In polar solvents of type II, hydration is quite unfavorable, and essentially no hydrates are expected in these media, except perhaps at very large water concentrations (although, in such a case, the medium cannot be simply described as an organic solvent). In polar solvents of type I, the situation is intermediate, and dihydration is favorable in some cases (acetone, acetonitrile) and unfavorable in others (DMSO). It is interesting to note that first hydration processes in coordinating solvents (of either type I or type II), where a water molecule must displace a solvent molecule coordinated to Mg, exhibit values of DeltaH > 0 and DeltaS > 0, in sharp contrast to first hydration processes in nonpolar media. The present results represent the first theoretical attempt to rationalize the large amount of experimental data on hydration and aggregation of Chla in aqueous organic media that have been accumulated over the past four decades. The data stress, in particular, the key role of Chla dihydrates, a point that has been the object of intense debate in the literature. Clearly, dihydrates are found to be more stable than monohydrates owing to a particular structure in which cooperative interactions occur between the water molecules and Chla. The calculations also explain the irregular behavior observed for Chla in aqueous THF or pyridine: In these media, Chla remains basically unhydrated because the Chla-solvent adducts are stabilized by strong dispersion interactions. PMID:20020703

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

    PubMed

    Ren, Bo; Dong, Hai; Ramström, Olof

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    PubMed

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

    2015-11-21

    We apply our recently developed generalized Flory-Huggins (FH) type theory for the competitive solvation of polymers by two mixed solvents to explain general trends in the variation of phase boundaries and solvent quality (quantified by the second osmotic virial coefficient B2) with solvent composition. The complexity of the theoretically predicted miscibility patterns for these ternary mixtures arises from the competitive association between the polymer and the solvents and from the interplay of these associative interactions with the weak van der Waals interactions between all components of the mixture. The main focus here lies in determining the influence of the free energy parameters for polymer-solvent association (solvation) and the effective FH interaction parameters {???} (driving phase separation) on the phase boundaries (specifically the spinodals), the second osmotic virial coefficient B2, and the relation between the positions of the spinodal curves and the theta temperatures at which B2 vanishes. Our classification of the predicted miscibility patterns is relevant to numerous applications of ternary polymer solutions in industrial formulations and the use of mixed solvent systems for polymer characterization, such as chromatographic separation where mixed solvents are commonly employed. A favorable comparison of B2 with experimental data for poly(methyl methacrylate)/acetonitrile/methanol (or 1-propanol) solutions only partially supports the validity of our theoretical predictions due to the lack of enough experimental data and the neglect of the self and mutual association of the solvents. PMID:26590552

  4. Nuclear spin hyperpolarization of the solvent using signal amplification by reversible exchange (SABRE).

    PubMed

    Moreno, Karlos X; Nasr, Khaled; Milne, Mark; Sherry, A Dean; Goux, Warren J

    2015-08-01

    Here we report the polarization of the solvent OH protons by SABRE using standard iridium-based catalysts under slightly acidic conditions. Solvent polarization was observed in the presence of a variety of structurally similar N-donor substrates while no solvent enhancement was observed in the absence of substrate or para-hydrogen (p-H2). Solvent polarization was sensitive to the polarizing field and catalyst:substrate ratio in a manner similar to that of substrate protons. SABRE experiments with pyridine-d5 suggest a mechanism where hyperpolarization is transferred from the free substrate to the solvent by chemical exchange while measured hyperpolarization decay times suggest a complimentary mechanism which occurs by direct coordination of the solvent to the catalytic complex. We found the solvent hyperpolarization to decay nearly 3 times more slowly than its characteristic spin-lattice relaxation time suggesting that the hyperpolarized state of the solvent may be sufficiently long lived (∼20s) to hyperpolarize biomolecules having exchangeable protons. This route may offer future opportunities for SABRE to impact metabolic imaging. PMID:26037136

  5. Nuclear spin hyperpolarization of the solvent using signal amplification by reversible exchange (SABRE)

    NASA Astrophysics Data System (ADS)

    Moreno, Karlos X.; Nasr, Khaled; Milne, Mark; Sherry, A. Dean; Goux, Warren J.

    2015-08-01

    Here we report the polarization of the solvent OH protons by SABRE using standard iridium-based catalysts under slightly acidic conditions. Solvent polarization was observed in the presence of a variety of structurally similar N-donor substrates while no solvent enhancement was observed in the absence of substrate or para-hydrogen (p-H2). Solvent polarization was sensitive to the polarizing field and catalyst:substrate ratio in a manner similar to that of substrate protons. SABRE experiments with pyridine-d5 suggest a mechanism where hyperpolarization is transferred from the free substrate to the solvent by chemical exchange while measured hyperpolarization decay times suggest a complimentary mechanism which occurs by direct coordination of the solvent to the catalytic complex. We found the solvent hyperpolarization to decay nearly 3 times more slowly than its characteristic spin-lattice relaxation time suggesting that the hyperpolarized state of the solvent may be sufficiently long lived (∼20 s) to hyperpolarize biomolecules having exchangeable protons. This route may offer future opportunities for SABRE to impact metabolic imaging.

  6. Coordinated education in dietetics.

    PubMed

    Lewis, M N; Beaudette, T M

    1977-06-01

    Details essential in implementing coordinated education in the preparation of the professional dietitian are described. Consideration is given to semantics, with clarification of terms posing problems in the smooth evolution of coordinated programs. Four phases of transition from the traditional to the coordinated process are illustrated: (a) Integration of the clinical phase into the undergraduate years; (b) interrelation of subject matter among departmental courses; (c) trans-disciplinary coordination; and (d) on-going evaluation of the curriculum in terms of professional practice. Also addressed are barriers to change in professional education. The ultimate goals are a balance between standardization and accountability and a climate in which academia has the liberty to meet demands in an innovative fashion. PMID:864150

  7. Developmental coordination disorder

    MedlinePlus

    Physical education and perceptual motor training (combining movement with tasks that require thinking, like math or reading) are the best ways to treat coordination disorder. Using a computer to ... Encouraging physical activity is important to prevent obesity.

  8. Organic Solvent Effects in Biomass Conversion Reactions.

    PubMed

    Shuai, Li; Luterbacher, Jeremy

    2016-01-01

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

  9. Luminescent lanthanide coordination polymers

    SciTech Connect

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

    1999-12-13

    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.

  10. Nanopapers for organic solvent nanofiltration.

    PubMed

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

    2014-06-01

    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

  11. NATURAL ATTENUATION OF CHLORINATED SOLVENTS

    EPA Science Inventory

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

  12. Improved Purex solvent scrubbing methods

    SciTech Connect

    Mailen, J.C.; Tallent, O.K.

    1984-01-01

    Studies of hydrazine and hydroxylamine salts as solvent scrubbing agents that can be decomposed into gases are summarized. Results from testing of countercurrent scrubbers and solid sorber columns that produce lesser amounts of permanent salts are reported. The status of studies of the acid-degradation of paraffin diluent and the options for removal of long-chain organic acids is given.

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

    SciTech Connect

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

    2013-02-01

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

  14. Cosmology and the weak interaction

    SciTech Connect

    Schramm, D.N. ):)

    1989-12-01

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

  15. Cosmology and the weak interaction

    NASA Technical Reports Server (NTRS)

    Schramm, David N.

    1989-01-01

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

  16. Replacement solvents for use in chemical synthesis

    DOEpatents

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

    2001-05-15

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

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

    PubMed Central

    Wittrup, Inge; Burau, Viola

    2015-01-01

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

  18. Color-weak compensation using local affine isometry based on discrimination threshold matching.

    PubMed

    Mochizuki, Rika; Kojima, Takanori; Lenz, Reiner; Chao, Jinhui

    2015-11-01

    We develop algorithms for color-weak compensation and color-weak simulation based on Riemannian geometry models of color spaces. The objective function introduced measures the match of color discrimination thresholds of average normal observers and a color-weak observer. The developed matching process makes use of local affine maps between color spaces of color-normal and color-weak observers. The method can be used to generate displays of images that provide color-normal and color-weak observers with a similar color difference experience. It can also be used to simulate the perception of a color-weak observer for color-normal observers. We also introduce a new database of measurements of color discrimination threshold data for color-normal and color-weak observers obtained at different lightness levels in CIELUV space. The compensation methods include compensations of chromaticity using local affine maps between chromaticity planes of color-normal and color-weak observers, and one-dimensional (1D) compensation on lightness. We describe how to determine correspondences between the origins of local coordinates in color spaces of color-normal and color-weak observers using a neighborhood expansion method. After matching the origins of the two coordinate systems, a local affine map is estimated by solving a nonlinear equation, or singular-value-decomposition (SVD). We apply the methods to natural images and evaluate their performance using the semantic differential (SD) method. PMID:26560924

  19. Weak-signal iterative holography.

    PubMed

    Watnik, Abbie T; Lebow, Paul S

    2015-04-01

    An iterative holographic table-top experiment is presented, where a recorded hologram is used to re-illuminate the initial target. With this beam shaping setup, more light is directed to the target for each iteration until a convergence limit is met. We experimentally examine convergence properties of this iterative hologram reconstruction approach for weak object signals and compare with theory. PMID:25967166

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

    PubMed

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

    2013-01-01

    We demonstrate evidence of a surface gap opening in topological insulator (TI) thin films of (Bi(0.57)Sb(0.43))(2)Te(3) below six quintuple layers through transport and scanning tunneling spectroscopy measurements. By effective tuning the Fermi level via gate-voltage control, we unveil a striking competition between weak localization and weak antilocalization at low magnetic fields in nonmagnetic ultrathin films, possibly owing to the change of the net Berry phase. Furthermore, when the Fermi level is swept into the surface gap of ultrathin samples, the overall unitary behaviors are revealed at higher magnetic fields, which are in contrast to the pure WAL signals obtained in thicker films. Our findings show an exotic phenomenon characterizing the gapped TI surface states and point to the future realization of quantum spin Hall effect and dissipationless TI-based applications. PMID:23198980

  1. The strong, weak and anomalous sides of weak topological insulators

    NASA Astrophysics Data System (ADS)

    Ringel, Zohar

    2013-03-01

    Disorder and topology can be thought of as two counter-driving forces. While the former pushes electron wave functions to localize in space, the latter requires them to remain coherent over the entire system. We study the interplay between these two on the surface of a ``weakly'' topological phase- the Weak Topological Insulator. Using arguments based on flux-insertions and locality, we show that such surfaces cannot undergo a localization transition even when the surface is strongly disordered. We also present a numerical study which further quantifies this result. We then reformulate the same notions, in field theory language, using a novel Z2-charge-anomaly. This anomaly generalizes the Z-charge-anomaly associated with edges of the Integer Quantum Hall Effect. Besides unifying various aspects of Topological Insulators, the anomaly allows us to calculate new topological properties of TIs in the presence of electric fields.

  2. Modeling solvent effects in optical lithography

    NASA Astrophysics Data System (ADS)

    Mack, Chris Alan

    A theoretical and experimental study into the effects of residual casting solvent on the lithographic properties of photoresist films is described. A modification to the common Fujita-Doolittle equation is proposed which provides an accurate description of the temperature and concentration dependence of solvent diffusivity in polymer systems. This model, in combination with a variable grid, finite difference time domain numerical solution to the diffusion equation, allows for calculation of the residual casting solvent content as a function of bake conditions. Using measurements of solvent content of a commercial i-line photoresist after post apply bake from a quartz crystal microbalance and radio-labeled solvent with scintillation counting, the model was verified. Analysis of this data has led to a calibrated model of solvent diffusivity as a function of solvent content and bake temperature, which can then predict solvent content as a function of depth into the photoresist for any bake conditions.

  3. A Triphasic Sorting System: Coordination Cages in Ionic Liquids.

    PubMed

    Grommet, Angela B; Bolliger, Jeanne L; Browne, Colm; Nitschke, Jonathan R

    2015-12-01

    Host-guest chemistry is usually carried out in either water or organic solvents. To investigate the utility of alternative solvents, three different coordination cages were dissolved in neat ionic liquids. By using (19) F NMR spectroscopy to monitor the presence of free and bound guest molecules, all three cages were demonstrated to be stable and capable of encapsulating guests in ionic solution. Different cages were found to preferentially dissolve in different phases, allowing for the design of a triphasic sorting system. Within this system, three coordination cages, namely Fe4 L6 2, Fe8 L12 3, and Fe4 L4 4, each segregated into a distinct layer. Upon the addition of a mixture of three different guests, each cage (in each separate layer) selectively bound its preferred guest. PMID:26494225

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

    SciTech Connect

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

    2013-05-06

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

  5. Flexible microporous coordination polymers

    SciTech Connect

    Uemura, Kazuhiro; Matsuda, Ryotaro; Kitagawa, Susumu . E-mail: kitagawa@sbchem.kyoto-u.ac.jp

    2005-08-15

    In a decade, many porous coordination polymers have been synthesized, providing a variety of properties ranging from storage, separation and exchange of guests in their cavities, magnetism, conductivity and catalysis by their frameworks. Recent advent of flexible porous coordination polymers, which exhibit elastic guest accommodation in contrast to rigid three-dimensional (3-D) frameworks of conventional porous materials, have acquired a position as a new class of porous materials. Such flexible porous properties induce highly selective guest accommodation and magnetic modulation, which could now be a unique class of practical materials. In this review, we introduce recent flexible porous coordination polymers (3-17) and their functional properties, categorizing with the four types of pores with framework deformation.

  6. Metastable postural coordination dynamics.

    PubMed

    James, Eric G

    2013-08-26

    The present study examined the coordination dynamics of the head and center of mass (COM) using accelerometry in quiet 1 and 2 leg stance with and without vision. The root mean square jerk of effectors was greater in 1 leg stance and without vision, and was greater for the head in 2 leg stance and greater at the COM for 1 leg stance. The coordination of the COM and head was more variable in 1 leg stance with vision than in the other stance and vision combinations. Both grouped and individual participant data showed metastable coordination dynamics with the presence of ghost attractors on both axes of motion that varied with the task. The findings indicated that stance and visual information conditions acted as control parameters, with increments in task difficulty increasing relative phase variability until a bifurcation in the metastable dynamics occurred in 1 leg stance without vision. PMID:23769730

  7. Is Water a Universal Solvent for Life?

    NASA Technical Reports Server (NTRS)

    Pohorill, Andrew

    2012-01-01

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

  8. 40 CFR Table 5 to Subpart Vvvv of... - Default Organic HAP Contents of Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart VVVV of Part 63 Protection of Environment ENVIRONMENTAL... Solvents and Solvent Blends As specified in § 63.5758(a)(6), when detailed organic HAP content data for solvent blends are not available, you may use the values in the following table: Solvent/solvent blend...

  9. 40 CFR Table 5 to Subpart Vvvv of... - Default Organic HAP Contents of Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart VVVV of Part 63 Protection of Environment ENVIRONMENTAL... Solvents and Solvent Blends As specified in § 63.5758(a)(6), when detailed organic HAP content data for solvent blends are not available, you may use the values in the following table: Solvent/solvent blend...

  10. Solvent Extraction of Furfural From Biomass

    NASA Technical Reports Server (NTRS)

    Humphrey, M. F.

    1984-01-01

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

  11. Restoring solvent for nuclear separation processes

    SciTech Connect

    Rief, D.J.

    1988-10-01

    Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate as an extractant diluted with a normal-paraffin hydrocarbon. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. In most processes, the solvent is recycled after cleaning. Solvent cleaning generally involves scrubbing with a sodium carbonate solution. Studies at the Savannah River Laboratory have shown that carbonate washing, although removing residual solvent activity, does not removed more solvent-soluble binding ligands (formed by solvent degradation), which hold fission products in the solvent. Treatment of the solvent with a solid adsorbent after carbonate washing removes binding ligands and significantly improves recycled solvent performance. Laboratory work to establish the advantage of adsorbent cleaning and the development of a full-scale adsorption process will be described. The application of this process for cleaning the first cycle solvent of a Savannah River Plant production process will be discussed.

  12. Restoring solvent for nuclear separation processes

    SciTech Connect

    Reif, D.J.

    1987-01-01

    Solvent extraction separation processes are used to recover usable nuclear materials from spent fuels. These processes involve the use of an extractant/diluent (solvent) for separation of the reusable actinides from unwanted fission products. The most widely used processes employ tributyl phosphate as an extractant diluted with a normal-paraffin hydrocarbon. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. In most processes, the solvent is recycled after cleaning. Solvent cleaning generally involves scrubbing with a sodium carbonate solution. Studies at the Savannah River Laboratory have shown that carbonate washing, although removing residual solvent activity, does not remove more solvent-soluble binding ligands (formed by solvent degradation), which hold fission products in the solvent. Treatment of the solvent with a solid adsorbent after carbonate washing removes binding ligands and significantly improves recycled solvent performance. Laboratory work to establish the advantage of adsorbent cleaning and the development of a full-scale adsorption process is described. The application of this process for cleaning the first cycle solvent of a Savannah River Plant production process is discussed.

  13. Firing of pulverized solvent refined coal

    DOEpatents

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

    1986-01-01

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

  14. On projective coordinate spaces

    NASA Astrophysics Data System (ADS)

    Ćiftçi, Süleyman; Erdoǧan, Fatma Özen

    2015-09-01

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

  15. Coordinate Standard Measurement Development

    SciTech Connect

    Hanshaw, R.A.

    2000-02-18

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

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

    NASA Astrophysics Data System (ADS)

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

    1995-04-01

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

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

    SciTech Connect

    Di Lorenzo, Antonio

    2014-06-15

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

  18. Tomography and weak lensing statistics

    SciTech Connect

    Munshi, Dipak; Coles, Peter; Kilbinger, Martin E-mail: peter.coles@astro.cf.ac.uk

    2014-04-01

    We provide generic predictions for the lower order cumulants of weak lensing maps, and their correlators for tomographic bins as well as in three dimensions (3D). Using small-angle approximation, we derive the corresponding one- and two-point probability distribution function for the tomographic maps from different bins and for 3D convergence maps. The modelling of weak lensing statistics is obtained by adopting a detailed prescription for the underlying density contrast that involves hierarchal ansatz and lognormal distribution. We study the dependence of our results on cosmological parameters and source distributions corresponding to the realistic surveys such as LSST and DES. We briefly outline how photometric redshift information can be incorporated in our results. We also show how topological properties of convergence maps can be quantified using our results.

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

    DOEpatents

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

    2009-01-06

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

  2. Microphase separation in weakly charged hydrophobic polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Braun, O.; Boué, F.; Candau, F.

    2002-02-01

    Aqueous solutions of a well-defined poly(N-isopropylacrylamide-co-sodium 2-acrylamido-methyl propanesulfonate) (NIPAM/NaAMPS in a 95/5 molar ratio) have been investigated by means of small-angle neutron scattering (SANS) and rheological experiments as a function of temperature (25\\un{^circ C} leqslant T leqslant 60\\un{^circ C}) and polymer concentration (0.5\\un{wt%} leqslant C leqslant 12\\un{wt%}). The solutions remain optically transparent and isotropic over the whole temperature range, in contrast with the homopolyNIPAM which precipitates above its lower critical solution temperature (LCST = 32\\un{^circ C}). Upon addition of salt, the systems undergo a micro-macrophase separation. At temperatures above 45\\un{^circ C}, the SANS spectra exhibit a sharp peak at a scattering wave vector, q_max, which increases slightly with temperature. At high temperature (T sim 60\\un{^circ C}), the scattered intensity follows a power law I(q) sim q^{-4} in the asymptotic regime, characteristic of two-density media with sharp interfaces, and q_{max} is found to vary with polymer concentration as q_{max} sim C^{{0.22}}. Estimates of the typical sizes give values between 40 Å and 200 Å. These results provide a strong evidence of a thermally induced microphase separation, which is corroborated by the very sharp increases of the viscosity (over 2 decades) and of the stress relaxation time of the solutions, occurring in the temperature range where the scattering peak is observed. The results are discussed and compared with the theoretical models proposed for weakly charged polyelectrolytes in a poor solvent.

  3. Origins of Coordinate Searching.

    ERIC Educational Resources Information Center

    Kilgour, Frederick G.

    1997-01-01

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

  4. Block coordination copolymers

    SciTech Connect

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

    2012-12-04

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

  5. Sex Equity Coordinator's Handbook.

    ERIC Educational Resources Information Center

    Rubenstein, Dorothy; Sillman, Donna

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

  6. Talk Time Coordinator Handbook.

    ERIC Educational Resources Information Center

    Tacoma Community House, WA.

    This manual is designed to assist coordinators of an English-as-a-Second-Language discussion group program in program planning and administration. The program uses volunteers to conduct discussions on topics of interest to limited English speaking community members. The introductory section of the manual describes the program, outlines the…

  7. Block coordination copolymers

    SciTech Connect

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

    2014-11-11

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

  8. Profiling Computing Coordinators.

    ERIC Educational Resources Information Center

    Edwards, Sigrid; Morton, Allan

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

  9. Block coordination copolymers

    DOEpatents

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

    2012-11-13

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

  10. Chemical solvent effects during reactions in supercritical fluid solvents

    SciTech Connect

    Townsend, S.H.

    1988-01-01

    Neat pyrolysis and reaction in supercritical water were investigated for a collection of aromatic ether (phenethyl phenyl ether, dibenzyl ether, benzyl phenyl ether and phenyl ether) and fully-hydrocarbon (diphenylmethane, 1,2-diphenylethane and 1,3-diphenylpropane), model compounds, as well as one heterocyclic ether (dibenzofuran), toward gaining an understanding of the reactions of biomass and coal in supercritical fluid solvents. Analysis of the reaction products and the derived pathways and kinetics from the neat pyrolysis of each model compound provided a baseline with which the results from its reactions in water could be compared. Orthogonal sets of experiments separately examined the impact of reduced water loading on the rates of reaction and on product selectivities. This approach enable the discovery that, as a supercritical fluid extraction solvent, water was capable of participating as a reactant during the solvolysis of certain chemical moieties. A hydrolysis pathway was elucidated that operated in parallel with the thermal pathways of neat pyrolysis for phenethyl phenyl ether, dibenzyl ether and benzyl phenyl ether. 1,2-Diphenylethane and 1,3-diphenylpropane underwent only pyrolysis, and phenyl ether, diphenylmethane and dibenzofuran were all found to be thermally stable, under the conditions explored by this investigation. Kinetics analysis of the experimental data for phenethyl phenyl ether and dibenzyl ether enable decoupling of the rate constants governing pyrolysis and solvolysis. These results were extended to describe the reactions of a class of compounds having a saturated carbon to which was attached a heteroatom-containing leaving group.

  11. The thermodynamics of solvent exchange.

    PubMed

    Schellman, J A

    1994-08-01

    A model for solvation in mixed solvents, which was developed for the free energy and preferential interaction [J. A. Schellman (1987), Biopolymers, Vol. 26, pp. 549-559; (1990), Biophysical Chemistry, Vol. 37, pp. 121-140; (1993), Biophysical Chemistry, Vol. 45, pp. 273-279], is extended in this paper to cover the thermal properties: enthalpy, entropy, and heat capacity. An important result is that the enthalpy of solvation H(ex)2 responds directly to the fraction of site occupation. This differs from the free energy G(ex)2 and preferential interaction gamma 32, which are measures of the excess binding above a random distribution of solvent molecules. In other words, the enthalpy is governed by K while G(ex)2 and gamma 32 are governed by (K-1) where K is the equilibrium constant on a mole fraction scale [Schellman (1987)]. The solvation heat capacity Cpex2 consists of two term: (1) the intrinsic heat capacity of species in solution with no change in composition, and (2) a term that accounts for the change in composition that accompanies solvent exchange. Binding to biological macromolecules is heterogeneous but experimentalists must use binding isotherms that assume the homogeneity of sites. Equations are developed for the interpretation of the experimental parameters (number of sites nexp, equilibrium constant Kexp, and enthalpy, delta hexp), when homogeneous formulas are applied to the heterogeneous case. It is shown that the experimental parameters for the occupation and enthalpy are simple functions of the moments of the distribution of equilibrium constants over the sites. In general, nexp is greater than the true number of sites and Kexp is greater than the average of the equilibrium constants. The free energy and preferential interaction can be fit to a homogeneous formula, but the parameters of the curve are not easily represented in terms of the moments of distributions over the sites. The strengths and deficiencies of this type of thermodynamic model are discussed. PMID:8075384

  12. SOLVENT EXTRACTION PROCESS FOR PLUTONIUM

    DOEpatents

    Seaborg, G.T.

    1959-04-14

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

  13. Assembly of Cerium(III) 2,2?-Bipyridine-5,5?-dicarboxylate-based MetalOrganic Frameworks by Solvent Tuning

    SciTech Connect

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

    2014-07-02

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

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

    NASA Astrophysics Data System (ADS)

    Mishra, Shawn; Keten, Sinan

    2013-01-01

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

  15. Tagged-weak {pi} method

    SciTech Connect

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

    2011-02-15

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

  16. Electromagnetic weak turbulence theory revisited

    SciTech Connect

    Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.; Pavan, J.

    2012-10-15

    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.

  17. Weak lensing by galaxy troughs

    NASA Astrophysics Data System (ADS)

    Gruen, Daniel

    2016-06-01

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

  18. Weak lensing by nearby structures

    NASA Astrophysics Data System (ADS)

    Gould, Andrew; Villumsen, Jens

    1994-06-01

    Weak gravitational lensing due to nearby structures, such as the Coma Cluster and the Local Supercluster, can be expected to polarize images of distant galaxies by Omicron(2 x 10-3Omega) with coherence over scales of tens of square degrees. The Sloan survey, which will image approximately greater than 104 galaxies deg-2 over pi steradians, should be sensitive to polarizations of approximately 0.1%A-1/2, where A is the area in square degrees. By measuring the polarization, one could determine Omega in local structures and compare this value to that derived from a variety of other techniques.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

    PubMed

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders. PMID:26542108

  1. Shared Activity Coordination

    NASA Technical Reports Server (NTRS)

    Clement, Bradley J.; Barrett, Anthony C.

    2003-01-01

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

  2. Coerced coordination, not cooperation.

    PubMed

    Soler, Montserrat; Lenfesty, Hillary L

    2016-01-01

    Norenzayan et al. propose that Big God (BG) religions are large-group cooperative enterprises that promote internal harmony and higher fertility, resulting in "mutually beneficial exchanges" for those involved. We examine the possible distributions of costs and benefits within BG religions and propose that they are, instead, successful coordinating mechanisms that rely on intragroup competition and exploitation between the classes and sexes. PMID:26948742

  3. The solvent component of macromolecular crystals.

    PubMed

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

    2015-05-01

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

  4. Weak antilocalisation in topological insulators

    NASA Astrophysics Data System (ADS)

    Bi, Xintao; Hankiewicz, Ewelina; Culcer, Dimitrie

    2014-03-01

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

  5. The weak scale from BBN

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  6. Hipparchus' coordinate system

    NASA Astrophysics Data System (ADS)

    Duke, Dennis W.

    2002-07-01

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

  7. Coordinating Shared Activities

    NASA Technical Reports Server (NTRS)

    Clement, Bradley

    2004-01-01

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

  8. Asphaltene aggregation in organic solvents.

    PubMed

    Oh, Kyeongseok; Ring, Terry A; Deo, Milind D

    2004-03-01

    Asphaltenic solids formed in the Rangely field in the course of a carbon dioxide flood and heptane insolubles in the oil from the same field were used in this study. Four different solvents were used to dissolve the asphaltenes. Near-infrared (NIR) spectroscopy was used to determine the onset of asphaltene precipitation by heptane titration. When the onset values were plotted versus asphaltene concentrations, distinct break points (called critical aggregation concentrations (CAC) in this paper) were observed. CACs for the field asphaltenes dissolved in toluene, trichloroethylene, tetrahydrofuran, and pyridine occurred at concentrations of 3.0, 3.7, 5.0, and 8.2 g/l, respectively. CACs are observed at similar concentrations as critical micelle concentrations (CMC) for the asphaltenes in the solvents employed and can be interpreted to be the points at which rates of asphaltene aggregations change. CMC values of asphaltenes determined from surface tension measurements (in pyridine and TCE) were slightly higher than the CAC values measured by NIR onset measurements. The CAC for heptane-insoluble asphaltenes in toluene was 3.1 g/l. Thermal gravimetric analysis (TGA) and elemental compositions of the two asphaltenes showed that the H/C ratio of the heptane-insoluble asphaltenes was higher and molecular weight (measured by vapor pressure osmometry) was lower. PMID:14757097

  9. Superfluid helium-4 weak links

    NASA Astrophysics Data System (ADS)

    Hoskinson, Emile Michael

    Josephson effects in superconductors, since their discovery in 1962, have not only provided a fascinating example of the counter-intuitive behavior of macroscopic quantum systems, but have also given rise to important technologies. The search for Josephson effects in superfluid 4He began not long after their discovery in superconductors, in 1962. We report, more that four decades later, the first observation of Josephson frequency quantum oscillation in superfluid 4He. We observe these oscillations in a 65 x 65 array of sub-micron sized apertures drilled in a 50 nm thick silicon nitrite membrane. We find that these oscillations can be driven not only by a pressure difference applied across the array, but also by a temperature difference. The frequency of the oscillations obeys the Josephson frequency relation, fj = Deltamu/h, where h is Plank's constant and Deltamu = m4(Delta P/rho - sDeltaT) is the chemical potential difference across the array. Furthermore, we find that for temperatures a few mK below the superfluid transition temperature T lambda, the amplitude of the oscillations indicates that they are occurring synchronously in all apertures of the array. We have developed a method of extracting the current-phase relation of the super-fluid 4He array from the response of the cell to a step in the chemical potential difference across the array. When the current-phase relation is plotted as a function of temperature near T lambda, we observe a cross-over from a low-temperature strong coupling regime in which the Josephson frequency oscillation is a result of periodically generated phase slips associated with singly quantized vortices, to a weak coupling regime exhibiting the sinusoidal current-phase signature of the Josephson effect. We have investigated the synchronicity of the oscillations in the array in the strong coupling regime as a function of temperature. We find that as the temperature drops, the apertures become less and less synchronous. We suggest several possible explanations for this behavior, including the idea that as the temperature rises toward the cross-over to the weak coupling regime, the vortex phase slip mechanism gives way to a wave function collapse mechanism. Finally, we present a "Chemical potential battery" for superfluid 4He weak link cells, whereby a constant heater power is used to generate a constant chemical potential difference, giving rise to steady Josephson frequency oscillations. This may be an ideal method of operating a superfluid 4He dc-SQUID, a device constructed from two weak link arrays in a torus, which will be highly sensitive to rotation. The experiments reported in this dissertation represent a breakthrough in superfluid 4He weak link research, and provide a big step in the direction of a practical superfluid dc-SQUID operating at 2 K, a regime accessible to mechanical cryo-coolers. Such a device may find application in geodesy, detection of rotational seismic waves, and basic physics.

  10. Supramolecular transformations within discrete coordination-driven supramolecular architectures.

    PubMed

    Wang, Wei; Wang, Yu-Xuan; Yang, Hai-Bo

    2016-05-01

    In this review, a comprehensive summary of supramolecular transformations within discrete coordination-driven supramolecular architectures, including helices, metallacycles, metallacages, etc., is presented. Recent investigations have demonstrated that coordination-driven self-assembled architectures provide an ideal platform to study supramolecular transformations mainly due to the relatively rigid yet dynamic nature of the coordination bonds. Various stimuli have been extensively employed to trigger the transformation processes of metallosupramolecular architectures, such as solvents, concentration, anions, guests, change in component fractions or chemical compositions, light, and post-modification reactions, which allowed for the formation of new structures with specific properties and functions. Thus, it is believed that supramolecular transformations could serve as another highly efficient approach for generating diverse metallosupramolecular architectures. Classified by the aforementioned various stimuli used to induce the interconversion processes, the emphasis in this review will be on the transformation conditions, structural changes, mechanisms, and the output of specific properties and functions upon induction of structural transformations. PMID:27009833

  11. A two-dimensional silver(I) coordination polymer constructed from 4-aminophenylarsonate and triphenylphosphane: poly[[(μ₃-4-aminophenylarsonato-κ³N:O:O)(triphenylphosphane-κP)silver(I)] monohydrate].

    PubMed

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

    2015-04-01

    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 μ3-κ(3)N:O:O-tridentate coordination mode connecting two dinuclear units, resulting in a neutral [Ag(Hapa)(PPh3)]n layer lying parallel to the (101̄) 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 π-π 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

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

    SciTech Connect

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

    2012-06-15

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

  13. Solvent Extraction External Radiation Stability Testing

    SciTech Connect

    Peterson, R.A.

    2001-01-05

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

  14. Accelerated solvent extraction for natural products isolation.

    PubMed

    Mottaleb, Mohammad A; Sarker, Satyajit D

    2012-01-01

    Accelerated solvent extraction (ASE(®)), first introduced in 1995, is an automated rapid extraction technique that utilizes common solvents at elevated temperature and pressure, and thereby increases the efficiency of extraction of organic compounds from solid and semisolid matrices. ASE(®) allows extractions for sample sizes 1-100 g in minutes, reduces solvent uses dramatically, and can be applied to a wide range of matrices, including natural products. PMID:22367894

  15. Femtosecond dynamics in hydrogen-bonded solvents

    SciTech Connect

    Castner, E.W. Jr.; Chang, Y.J.

    1993-09-01

    We present results on the ultrafast dynamics of pure hydrogen-bonding solvents, obtained using femtosecond Fourier-transform optical-heterodyne-detected, Raman-induced Kerr effect spectroscopy. Solvent systems we have studied include the formamides, water, ethylene glycol, and acetic acid. Inertial and diffusive motions are clearly resolved. We comment on the effect that such ultrafast solvent motions have on chemical reactions in solution.

  16. Weak transitions in lattice QCD

    SciTech Connect

    Maturana, G.

    1984-01-01

    Some techniques to calculate the effects of the strong interactions on the matrix elements of weak processes are described. The lattice formulation of Quantum Chromodynamics is used to account for the low energy gluons, and the corresponding numerical methods are explained. The high energy contributions are included in effective lagrangians and the problem of matching the different scales related to the renormalization of the operators and wavefunctions is also discussed. The ..delta..l = 1/2 enhancement rule and the K/sup 0/-anti-K/sup 0/ are used to illustrate these techniques and the results of a numerical calculation is reported. The values obtained are very encouraging and they certainly show good qualitative agreement with the experimental values. The emphasis is on general techniques, and in particular, several improvements to this particular calculation are proposed.

  17. Behaviour of Weak Shales in Underground Environments

    NASA Astrophysics Data System (ADS)

    Martin, C. Derek; Giger, Silvio; Lanyon, G. W.

    2016-02-01

    Predicting the ground response for tunnels in weak shales remains challenging. Predicting the ground response is challenged by difficulties in characterising the material, and our ability to predict deformations that are driven by coupled hydromechanical processes, when this material yields. The techniques that are used for characterising weak shales are reviewed, and three case histories are examined that demonstrate the behaviour of these weak rocks during tunnelling. A general framework is provided for assessing the squeezing potential for weak shales.

  18. Weakly ionized cerium plasma radiography

    NASA Astrophysics Data System (ADS)

    Sato, Eiichi; Hayasi, Yasuomi; Germer, Rudolf; Koorikawa, Yoshitake; Murakami, Kazunori; Tanaka, Etsuro; Mori, Hidezo; Kawai, Toshiaki; Ichimaru, Toshio; Obata, Fumiko; Takahashi, Kiyomi; Sato, Sigehiro; Takayama, Kazuyoshi; Ido, Hideaki

    2004-02-01

    In the plasma flash x-ray generator, high-voltage main condenser of about 200 nF is charged up to 55 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is of a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to a rod cerium target of 3.0 mm in diameter by electric field in the x-ray tube, the weakly ionized linear plasma, which consists of cerium ions and electrons, forms by target evaporating. At a charging voltage of 55 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, weakly ionized cerium plasma formed, and the K-series characteristic x-ray intensities increased. The x-ray pulse widths were about 500 ns, and the time-integrated x-ray intensity had a value of about 40 μC/kg at 1.0 m from x-ray source with a charging voltage of 55 kV. In the angiography, we employed a film-less computed radiography (CR) system and iodine-based microspheres. Because K-series characteristic x-rays are absorbed easily by the microspheres, high-contrast angiography has been performed.

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

    SciTech Connect

    Michael T. Klein

    2000-01-01

    There are several aspects of the Direct Coal Liquefaction process which are not fully understood and which if better understood might lead to improved yields and conversions. Among these questions are the roles of the catalyst and the solvent. While the solvent is known to act by transfer of hydrogen atoms to the free radicals formed by thermal breakdown of the coal in an uncatalyzed system, in the presence of a solid catalyst as is now currently practiced, the yields and conversions are higher than in an uncatalyzed system. The role of the catalyst in this case is not completely understood. DOE has funded many projects to produce ultrafine and more active catalysts in the expectation that better contact between catalyst and coal might result. This approach has met with limited success probably because mass transfer between two solids in a fluid medium i.e. the catalyst and the coal, is very poor. It is to develop an understanding of the role of the catalyst and solvent in Direct Liquefaction that this project was initiated. Specifically it was of interest to know whether direct contact between the coal and the catalyst was important. By separating the solid catalyst in a stainless steel basket permeable to the solvent but not the coal in the liquefaction reactor, it was shown that the catalyst still maintains a catalytic effect on the liquefaction process. There is apparently transfer of hydrogen atoms from the catalyst through the basket wall to the coal via the solvent. Strong hydrogen donor solvents appear to be more effective in this respect than weak hydrogen donors. It therefore appears that intimate contact between catalyst and coal is not a requirement, and that the role of the catalyst may be to restore the hydrogen donor strength to the solvent as the reaction proceeds. A range of solvents of varying hydrogen donor strength was investigated. Because of the extensive use of thermogravimetric analysis in this laboratory in was noted that the peak temperature for volatile evolution from coal was a reliable measure of coal rank. Because of this observation, a wide variety of coals of a wide range of ranks was investigated. It was shown in this work that measuring the peak temperature for volatile evolution was quite a precise indicator of rank and correlated closely wit the rank values obtained by measuring vitrinite reflectance, a more difficult measurement to make. This prompted the desire to know the composition of the volatile materials evolved as a function of coal rank. This was then measured by coupling a TGA to a mass spectrometer using laser activation and photoionization detection TG-PI-MS. The predominant species in volatiles of low rank coal turned out to be phenols with some alkenes. As the rank increases, the relative amount of alkenes and aromatic hydrocarbons increases and the oxygenated species decrease. It was shown that these volatiles were actually pyrolitic products and not volatilization products of coal. Solvent extraction experiments coupled with TG-PI-MS indicates that the low oiling and more extractable material are essentially similar in chemical types to the non-extractable portions but apparently higher molecular weight and therefor less extractable.

  20. Screening of TODGA/TBP/OK solvent mixtures for the grouped extraction of actinides

    NASA Astrophysics Data System (ADS)

    Brown, Jamie; Carrott, Michael J.; Fox, O. Danny; Maher, Chris J.; Mason, Chris; McLachlan, Fiona; Sarsfield, Mark J.; Taylor, Robin J.; Woodhead, Dave A.

    2010-03-01

    The solvent combination N,N,N'N'- tetraoctyl diglycolamide (TODGA)/tributyl phosphate (TBP)/odourless kerosene (OK) is examined as a potential solvent system for a Grouped Actinide Extraction (GANEX) process to separate all of the actinides from fission products when reprocessing spent nuclear fuel. A series of solvent extraction batch experiments were performed with a range of TODGA/TBP/OK solvent combinations to assess the sensitivity of distribution values for a number of key elements towards [TBP] (0 — 1.1M), [TODGA] (0.1-0.4M), [HNO3] (0.1-5M) and heavy metal loading ([U] 0-200g/l). There is little impact on DAm or DEu across the solvent range and no influence from U loading. Excellent DNp values (> 10) are observed, increasing with increasing [TODGA], with [TBP] having little influence. Such high DNp values may obviate the need for preconditioning of dissolved fuel feeds to control Np routing. High DTc values are found even at 5M HNO3, therefore Tc is expected to remain in the solvent phase. Both Pu(III) and Pu(IV) are readily extracted with DPu(III) > DPu(IV). Uranium is extracted by both TBP and TODGA and TBP is shown to effectively compete with TODGA for uranium coordination sites. Third phase formation occurs at high [U] loading and [HNO3] but is suppressed by increasing [TBP].

  1. Solvent recovery system provides timely compliance solution

    SciTech Connect

    1996-11-01

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

  2. Process for hydrogenating coal and coal solvents

    DOEpatents

    Tarrer, Arthur R.; Shridharani, Ketan G.

    1983-01-01

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

  3. Solvent effects on photostability of metal dithizonates

    SciTech Connect

    Chen, N.L.; Lai, E.P.C.

    1987-01-01

    The photodecompositions of five typical metal dithizonates have been studied in various solvents under the irradiation of 310-nm UV light and ordinary indoor illumination. In methylene chloride and chloroform the decomposition mechanism is confirmed to be the interaction of these metal dithizonates and the oxidants arising from the photodecomposition of the solvent. In carbon tetrachloride the decompositions were fast and were observed to be first-order in the dithizonates. In benzene, no apparent photodecomposition was found. Since these solvent effects are independent of the metal, benzene is probably the best solvent for the extraction-spectrophotometry of unstable dithizonates.

  4. MCU MATERIALS COMPATIBILITY WITH CSSX SOLVENT

    SciTech Connect

    Fondeur, F

    2006-01-13

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

  5. Organic solvent use in enterprises in Japan.

    PubMed

    Nagasawa, Yasuhiro; Ukai, Hirohiko; Okamoto, Satoru; Samoto, Hajime; Itoh, Kenji; Moriguchi, Jiro; Sakuragi, Sonoko; Ohashi, Fumiko; Takada, Shiro; Kawakami, Tetsuya; Ikeda, Masayuki

    2011-01-01

    This study was initiated to elucidate possible changes in types of organic solvents (to be called solvents in short) used in enterprises in Japan through comparison of current solvent types with historical data since 1983. To investigate current situation in solvent use in enterprises, surveys were conducted during one year of 2009 to 2010. In total, workroom air samples in 1,497 unit workplaces with solvent use were analyzed in accordance with regulatory requirements. Typical use pattern of solvents was as mixtures, accounting for >70% of cases. Adhesives spreading (followed by adhesion) was relatively common in small-scale enterprises, whereas printing and painting work was more common in middle-scale ones, and solvent use for testing and research purpose was basically in large-scaled enterprises. Through-out printing, painting, surface coating and adhesive application, toluene was most common (being detected in 49 to 82% of workplaces depending on work types), whereas isopropyl alcohol was most common (49%) in degreasing, cleaning and wiping workplaces. Other commonly used solvents were methyl alcohol, ethyl acetate and acetone (33 to 37%). Comparison with historical data in Japan and literature-retrieved data outside of Japan all agreed with the observation that toluene is the most commonly used solvent. Application of trichloroethylene and 1,1,1-trichloroethane, once common in 1980s, has ceased to exist in recent years. PMID:21697614

  6. Work Coordination Engine

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

  7. Multipole Structure and Coordinate Systems

    ERIC Educational Resources Information Center

    Burko, Lior M.

    2007-01-01

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

  8. Solvent-driven chemical motor

    NASA Astrophysics Data System (ADS)

    Mitsumata, Tetsu; Ikeda, Kazuo; Gong, Jian Ping; Osada, Yoshihito

    1998-10-01

    A solvent-driven chemical motor using amphiphilic polymer gel has been fabricated. The driving force of the gel originates from the surface tension of spreading organic fluid which is pumped out by osmotic and hydrostatic pressures in the gel. A tetrahydrofurane-swollen gel equipped with a spouting hole made a controlled translational motion with a velocity of 77 mm/s or rotational motion with a maximum speed of 400 rpm and a torque of 10-9-10-7 Nm on the water surface. A generator to produce an electric power with a maximum electromotive force of 15 mV and electric power of 0.2 μW has also been constructed. The successful fabrication of gel motor may produce a new era of soft machine systems which work without pollution and unnecessary intermediates.

  9. Fast geodetic coordinate transformations

    NASA Astrophysics Data System (ADS)

    Carlson, N. A.

    1980-07-01

    The shape of the earth and its gravity field are well represented by a reference ellipsoid. New algorithms are presented for computationally efficient transformations between geodetic ellipsoidal (altitude, latitude, longitude) and geocentric Cartesian coordinates, including high-accuracy direct approximations and fast iterative exact solution. These algorithms provide significant speed and accuracy advantages over existing techniques. Terrestrial navigation equations based on the new algorithms are developed, and extended to various navigation functions from inertial data processing to Kalman filtering. Applied to a typical GPS/inertial navigator, this mechanization provides a 10% to 15% speed increase over conventional mechanizations.

  10. Diagnosing developmental coordination disorders.

    PubMed

    Kirby, Amanda; Sugden, David; Purcell, Catherine

    2014-03-01

    Developmental coordination disorder (DCD) affects around 5% of children and commonly overlaps with other developmental disorders including: attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASDs) and specific language impairment (SLI). There is evidence to demonstrate the wide-ranging impact on all areas of functioning including psychiatric and learning domains. There is increasing evidence of the continuing impact into adulthood and the long-term negative effects on relationships and employment. There is a need for early identification and intervention to limit the likelihood of these secondary consequences from emerging. This paper addresses the diagnosis of DCD. PMID:24255567

  11. Green Solvents for Precision Cleaning

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    Aerospace machinery used in liquid oxygen (LOX) fuel systems must be precision cleaned to achieve a very low level of non-volatile residue (< 1 mg0.1 m2), especially flammable residue. Traditionally chlorofluorocarbons (CFCs) have been used in the precision cleaning of LOX systems, specifically CFC 113 (C2Cl3F3). CFCs have been known to cause the depletion of ozone and in 1987, were banned by the Montreal Protocol due to health, safety and environmental concerns. This has now led to the development of new processes in the precision cleaning of aerospace components. An ideal solvent-replacement is non-flammable, environmentally benign, non-corrosive, inexpensive, effective and evaporates completely, leaving no residue. Highlighted is a green precision cleaning process, which is contaminant removal using supercritical carbon dioxide as the environmentally benign solvent. In this process, the contaminant is dissolved in carbon dioxide, and the parts are recovered at the end of the cleaning process completely dry and ready for use. Typical contaminants of aerospace components include hydrocarbon greases, hydraulic fluids, silicone fluids and greases, fluorocarbon fluids and greases and fingerprint oil. Metallic aerospace components range from small nuts and bolts to much larger parts, such as butterfly valves 18 in diameter. A fluorinated grease, Krytox, is investigated as a model contaminant in these preliminary studies, and aluminum coupons are employed as a model aerospace component. Preliminary studies are presented in which the experimental parameters are optimized for removal of Krytox from aluminum coupons in a stirred-batch process. The experimental conditions investigated are temperature, pressure, exposure time and impeller speed. Temperatures of 308 - 423 K, pressures in the range of 8.3 - 41.4 MPa, exposure times between 5 - 60 min and impeller speeds of 0 - 1000 rpm were investigated. Preliminary results showed up to 86 cleaning efficiency with the moderate processing conditions of 323 K, 13.8 MPa, 30 min and 750 rpm.

  12. Cleanup of 7. 5% tributyl phosphate/n-paraffin solvent-extraction solvent

    SciTech Connect

    Reif, D.J.

    1987-02-01

    The HM process at the Savannah River Plant uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials which influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands which hold fission products in the solvent. Treatment of solvent by an alumina adsorption process removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale alumina adsorption process and the use of the process to clean HM process first cycle solvent is discussed.

  13. Canyon solvent cleaning with solid adsorbents. [HM Process solvent (TBP in n-paraffin)

    SciTech Connect

    Reif, D.J.

    1987-01-01

    The HM Process at the Savannah River Plant (SRP) uses 7.5% tributyl phosphate in n-paraffin as an extraction solvent. During use, the solvent is altered due to hydrolysis and radiolysis, forming materials that influence product losses, product decontamination, and separation efficiencies. Laboratory studies to improve online solvent cleaning have shown that carbonate washing, although removing residual solvent activity, does not remove binding ligands that hold fission products in the solvent. Treatment of solvent with a solid adsorbent removes binding ligands and significantly improves recycle solvent performance. Both laboratory work defining a full-scale adsorption process and the use of the process to clean HM Process first cycle solvent are presented.

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    DOEpatents

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

    1998-01-01

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

  17. Reducing systematic error in weak lensing cluster surveys

    SciTech Connect

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

    2014-05-10

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

  18. Analysis of weak interactions and Eotvos experiments

    NASA Technical Reports Server (NTRS)

    Hsu, J. P.

    1978-01-01

    The intermediate-vector-boson model is preferred over the current-current model as a basis for calculating effects due to weak self-energy. Attention is given to a possible violation of the equivalence principle by weak-interaction effects, and it is noted that effects due to weak self-energy are at least an order of magnitude greater than those due to the weak binding energy for typical nuclei. It is assumed that the weak and electromagnetic energies are independent.

  19. A thermobaric instability of Lagrangian vertical coordinate ocean models

    NASA Astrophysics Data System (ADS)

    Hallberg, Robert

    Lagrangian- (and isopycnic-) vertical coordinate ocean models are subject to an exponentially growing numerical instability in weakly stratified regions when thermobaricity is not accurately compensated. Inaccurate compensation for compressibility in the pressure gradient terms leads to pressure gradient truncation errors (due to the vertical discretization) that can drive the Lagrangian coordinate surfaces to reinforce these errors. It is possible to avoid this instability while using the full non-linear equation of state for seawater by using an optimal alternate discretization of the pressure gradient terms and extracting a slowly spatially varying reference compressibility that approximates the compressibility of the ocean's mean state.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. Continual coordination of shared activities

    NASA Technical Reports Server (NTRS)

    Clement, B. J.; Barrett, A.

    2002-01-01

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

  2. Solvation effects in complex-forming reactions. I. The effect of solvents on complex formation between seleno and thioanisoles and iodine

    SciTech Connect

    Safin, D.Kh.; Chmutova, G.A.; Solomonov, B.N.

    1986-02-10

    The enthalpies of solution of seleno- and thioanisoles in a large group of solvents, the constants and enthalpies of complex formation between both compounds and iodine, and the spectral characteristics of the complexes in the same solvents were measured and analyzed. In chemically inert solvents there are fairly clear relationships between the spectral and thermodynamic characteristics of the obtained Mulliken-type complexes, both groups of CTC (charge-transfer complex) parameters, and the universal intermolecular interaction functions of the solvent; a series of the characteristics of the complex were analyzed in relation to the behavior of the reagents. Such correlations are not observed in coordinating solvents, but the directions of the change in the enthalpies of complex formation with variation of the solvents can be predicted.

  3. Price schedules coordination for electricity pool markets

    NASA Astrophysics Data System (ADS)

    Legbedji, Alexis Motto

    2002-04-01

    We consider the optimal coordination of a class of mathematical programs with equilibrium constraints, which is formally interpreted as a resource-allocation problem. Many decomposition techniques were proposed to circumvent the difficulty of solving large systems with limited computer resources. The considerable improvement in computer architecture has allowed the solution of large-scale problems with increasing speed. Consequently, interest in decomposition techniques has waned. Nonetheless, there is an important class of applications for which decomposition techniques will still be relevant, among others, distributed systems---the Internet, perhaps, being the most conspicuous example---and competitive economic systems. Conceptually, a competitive economic system is a collection of agents that have similar or different objectives while sharing the same system resources. In theory, constructing a large-scale mathematical program and solving it centrally, using currently available computing power can optimize such systems of agents. In practice, however, because agents are self-interested and not willing to reveal some sensitive corporate data, one cannot solve these kinds of coordination problems by simply maximizing the sum of agent's objective functions with respect to their constraints. An iterative price decomposition or Lagrangian dual method is considered best suited because it can operate with limited information. A price-directed strategy, however, can only work successfully when coordinating or equilibrium prices exist, which is not generally the case when a weak duality is unavoidable. Showing when such prices exist and how to compute them is the main subject of this thesis. Among our results, we show that, if the Lagrangian function of a primal program is additively separable, price schedules coordination may be attained. The prices are Lagrange multipliers, and are also the decision variables of a dual program. In addition, we propose a new form of augmented or nonlinear pricing, which is an example of the use of penalty functions in mathematical programming. Applications are drawn from mathematical programming problems of the form arising in electric power system scheduling under competition.

  4. Recombination, Solvation and Reaction of CN Radicals Following Ultraviolet Photolysis of ICN in Organic Solvents.

    PubMed

    Coulter, Philip; Grubb, Michael P; Koyama, Daisuke; Sazanovich, Igor V; Greetham, Gregory M; Orr-Ewing, Andrew J

    2015-12-31

    The fates of CN radicals produced by ultraviolet (UV) photolysis of ICN in various organic solvents have been examined by transient electronic and vibrational absorption spectroscopy (TEAS and TVAS). Near-UV and visible bands in the TEAS measurement enable direct observation of the CN radicals and their complexes with the solvent molecules. Complementary TVAS measurements probe the products of CN-radical reactions. Geminate recombination to form ICN and INC is a minor pathway on the 150 fs -1300 ps time scales of our experiments in the chosen organic solvents; nonetheless, large infrared transition dipole moments permit direct observation of INC that is vibrationally excited in the C≡N stretching mode. The time constants for INC vibrational cooling range from 30 ps in tetrahydrofuran (THF) to 1400 ps in more weakly interacting solvents such as chloroform. The major channel for CN removal in the organic solvents is reaction with solvent molecules, as revealed by depletion of solvent absorption bands and growth of product bands in the TVA spectra. HCN is a reaction product of hydrogen atom abstraction in most of the photoexcited solutions, and forms with vibrational excitation in both the C-H and C≡N stretching modes. The vibrational cooling rate of the C≡N stretch in HCN depends on the solvent, and follows the same trend as the cooling rate of the C≡N stretch in INC. However, in acetonitrile solution an additional reaction pathway produces C3H3N2(•) radicals, which release HCN on a much longer time scale. PMID:26634787

  5. Weakly Interacting Disordered Electron Systems

    NASA Astrophysics Data System (ADS)

    Ekuma, C. E.; Terletska, H.; Yang, S.; Tam, K.-M.; Vidhyadhiraja, N. S.; Moreno, J.; Jarrell, M.

    2015-03-01

    We report on the interplay of interactions and disorder within the typical medium dynamical cluster approximation using the Anderson-Hubbard model. By the systematical incorporation of non-local spatial correlations and the diagonal disorder on an equal footing, we study the initial effects of electron interactions (U) in one (1D), two (2D), and three (3D) dimensions. Treating the interacting non-local cluster self-energy (?c(SOPT) [ cal G ~ ] (i , j ? i)) up to ?U2 order in the perturbation expansion, we obtain the ground-state phase diagram in 3D for the disorder induced paramagnetic metal to insulator transition in the presence of weak interactions. We find that the critical disorder strength (Wc), required to localize all states, increases with increasing U; implying that the metallic phase is stabilized by interactions. In 2D, our results agree with previous findings on the destruction of the insulating phase by U, while in 1D, we find strong competition between both phases. This work is supported by the NSF EPSCoR EPS-1003897. Supercomputer support is provided by LONI and HPC@LSU.

  6. Weak percolation on multiplex networks

    NASA Astrophysics Data System (ADS)

    Baxter, Gareth J.; Dorogovtsev, Sergey N.; Mendes, José F. F.; Cellai, Davide

    2014-04-01

    Bootstrap percolation is a simple but nontrivial model. It has applications in many areas of science and has been explored on random networks for several decades. In single-layer (simplex) networks, it has been recently observed that bootstrap percolation, which is defined as an incremental process, can be seen as the opposite of pruning percolation, where nodes are removed according to a connectivity rule. Here we propose models of both bootstrap and pruning percolation for multiplex networks. We collectively refer to these two models with the concept of "weak" percolation, to distinguish them from the somewhat classical concept of ordinary ("strong") percolation. While the two models coincide in simplex networks, we show that they decouple when considering multiplexes, giving rise to a wealth of critical phenomena. Our bootstrap model constitutes the simplest example of a contagion process on a multiplex network and has potential applications in critical infrastructure recovery and information security. Moreover, we show that our pruning percolation model may provide a way to diagnose missing layers in a multiplex network. Finally, our analytical approach allows us to calculate critical behavior and characterize critical clusters.

  7. A Universe without Weak Interactions

    SciTech Connect

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

    2006-04-07

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

  8. Weak percolation on multiplex networks.

    PubMed

    Baxter, Gareth J; Dorogovtsev, Sergey N; Mendes, José F F; Cellai, Davide

    2014-04-01

    Bootstrap percolation is a simple but nontrivial model. It has applications in many areas of science and has been explored on random networks for several decades. In single-layer (simplex) networks, it has been recently observed that bootstrap percolation, which is defined as an incremental process, can be seen as the opposite of pruning percolation, where nodes are removed according to a connectivity rule. Here we propose models of both bootstrap and pruning percolation for multiplex networks. We collectively refer to these two models with the concept of "weak" percolation, to distinguish them from the somewhat classical concept of ordinary ("strong") percolation. While the two models coincide in simplex networks, we show that they decouple when considering multiplexes, giving rise to a wealth of critical phenomena. Our bootstrap model constitutes the simplest example of a contagion process on a multiplex network and has potential applications in critical infrastructure recovery and information security. Moreover, we show that our pruning percolation model may provide a way to diagnose missing layers in a multiplex network. Finally, our analytical approach allows us to calculate critical behavior and characterize critical clusters. PMID:24827287

  9. Weakly Supervised Human Fixations Prediction.

    PubMed

    Zhang, Luming; Li, Xuelong; Nie, Liqiang; Yang, Yi; Xia, Yingjie

    2016-01-01

    Automatically predicting human eye fixations is a useful technique that can facilitate many multimedia applications, e.g., image retrieval, action recognition, and photo retargeting. Conventional approaches are frustrated by two drawbacks. First, psychophysical experiments show that an object-level interpretation of scenes influences eye movements significantly. Most of the existing saliency models rely on object detectors, and therefore, only a few prespecified categories can be discovered. Second, the relative displacement of objects influences their saliency remarkably, but current models cannot describe them explicitly. To solve these problems, this paper proposes weakly supervised fixations prediction, which leverages image labels to improve accuracy of human fixations prediction. The proposed model hierarchically discovers objects as well as their spatial configurations. Starting from the raw image pixels, we sample superpixels in an image, thereby seamless object descriptors termed object-level graphlets (oGLs) are generated by random walking on the superpixel mosaic. Then, a manifold embedding algorithm is proposed to encode image labels into oGLs, and the response map of each prespecified object is computed accordingly. On the basis of the object-level response map, we propose spatial-level graphlets (sGLs) to model the relative positions among objects. Afterward, eye tracking data is employed to integrate these sGLs for predicting human eye fixations. Thorough experiment results demonstrate the advantage of the proposed method over the state-of-the-art. PMID:26168451

  10. Weak Turbulence in Radiation Belts

    NASA Astrophysics Data System (ADS)

    Ganguli, Gurudas; Crabtree, Chris; Rudakov, Leonid

    2015-11-01

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

  11. 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...

  12. 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, ...

  13. Green chemicals: Searching for cleaner solvents

    SciTech Connect

    Lucas, A.

    1994-10-05

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

  14. Gallium complexes and solvent extraction of gallium

    SciTech Connect

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

    1988-05-03

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

  15. Industrial potential of organic solvent tolerant bacteria.

    PubMed

    Sardessai, Yogita N; Bhosle, Saroj

    2004-01-01

    Most bacteria and their enzymes are destroyed or inactivated in the presence of organic solvents. Organic solvent tolerant bacteria are a relatively novel group of extremophilic microorganisms that combat these destructive effects and thrive in the presence of high concentrations of organic solvents as a result of various adaptations. These bacteria are being explored for their potential in industrial and environmental biotechnology, since their enzymes retain activity in the presence of toxic solvents. This property could be exploited to carry out bioremediation and biocatalysis in the presence of an organic phase. Because a large number of substrates used in industrial chemistry, such as steroids, are water-insoluble, their bioconversion rates are affected by poor dissolution in water. This problem can be overcome by carrying out the process in a biphasic organic-aqueous fermentation system, wherein the substrate is dissolved in the organic phase and provided to cells present in the aqueous phase. In bioprocessing of fine chemicals such as cis-diols and epoxides using such cultures, organic solvents can be used to extract a toxic product from the aqueous phase, thereby improving the efficiency of the process. Bacterial strains reported to grow on and utilize saturated concentrations of organic solvents such as toluene can revolutionize the removal of such pollutants. It is now known that enzymes display striking new properties in the presence of organic solvents. The role of solvent-stable enzymes in nonaqueous biocatalysis needs to be explored and could result in novel applications. PMID:15176865

  16. REMEDIATING PESTICIDE CONTAMINATED SOILS USING SOLVENT EXTRACTION

    EPA Science Inventory

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

  17. 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...

  18. Solvation of rhodamine575 in some solvents

    NASA Astrophysics Data System (ADS)

    Sharma, Amit

    2016-05-01

    FTIR spectra of Rhodamine575 dye in powder form and in different solvents are reported. Positions of some of the observed FTIR bands show noticeable change in solvents. The bands, which shift, have contributions from the vibrational motion of nitrogen atoms of the ethylamine groups, oxygen atom of the carboxylic group attached to the phenyl ring and oxygen atom of the Xanthene ring.

  19. Remediating pesticide contaminated soils using solvent extraction

    SciTech Connect

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

    1996-12-31

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

  20. 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...

  1. SOLVENT-FREE ORGANIC SYNTHESES USING MICROWAVES

    EPA Science Inventory

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

  2. SOLVENT 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 ...

  3. 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...

  4. 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...

  5. Coal mining with a liquid solvent

    NASA Technical Reports Server (NTRS)

    Lawson, D. D.; Miller, C. G.

    1979-01-01

    Study suggests carbonated water can dissolve or suspend coal and carry it to surface. Mixture of carbon dioxide and water may be coal solvent that will make unmanned mining reality. When used with proposed process monitoring coal solubility with conventional strain gage, solvent is basis for rapid cost effective extraction of coal from underground seams.

  6. Pneumatic conveying of pulverized solvent refined coal

    DOEpatents

    Lennon, Dennis R.

    1984-11-06

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

  7. Supercritical-Multiple-Solvent Extraction From Coal

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  8. Improved Supercritical-Solvent Extraction of Coal

    NASA Technical Reports Server (NTRS)

    Compton, L.

    1982-01-01

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

  9. SOLVENT DISPERSION AND FLOW METER CALCULATION RESULTS

    SciTech Connect

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

    2013-06-21

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

  10. Characterization of Nanoparticles by Solvent Infrared Spectroscopy.

    PubMed

    Kiefer, Johannes; Grabow, Janet; Kurland, Heinz-Dieter; Müller, Frank A

    2015-12-15

    The characterization of the surface chemistry of nanoparticles using infrared spectroscopy of adsorbed solvents is proposed. In conventional IR spectroscopy of nanomaterials the capability of characterizing the chemistry of the surface is limited. To overcome these limitations, we record IR spectra of different solvents inside a fixed bed of the nanopowder to be tested. Using water and different alcohols as solvents enables the characterization of the nanomaterial's surface chemistry via the molecular interactions affecting the hydrogen-bonding network in the solvent. Different ceramic nanopowders (titania, two different iron oxides, and iron oxide nanocrystallites embedded in a closed silica matrix) are studied using water, ethanol, and n-butanol as solvents. The OH stretching region of the IR spectra reveals characteristic differences in the surface chemistry of the nanoparticles. The proposed method is fast and straightforward, and hence, it can be a versatile tool for rapid screening. PMID:26593634

  11. Toxic hepatitis in occupational exposure to solvents

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

    Zheng, Junrong; Fayer, Michael D.

    2008-01-01

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

  13. Network Coordinator Report

    NASA Technical Reports Server (NTRS)

    Himwich, Ed; Strand, Richard

    2013-01-01

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

  14. Coordinating Group report

    SciTech Connect

    Not Available

    1994-01-01

    In December 1992, western governors and four federal agencies established a Federal Advisory Committee to Develop On-site Innovative Technologies for Environmental Restoration and Waste Management (the DOIT Committee). The purpose of the Committee is to advise the federal government on ways to improve waste cleanup technology development and the cleanup of federal sites in the West. The Committee directed in January 1993 that information be collected from a wide range of potential stakeholders and that innovative technology candidate projects be identified, organized, set in motion, and evaluated to test new partnerships, regulatory approaches, and technologies which will lead to improve site cleanup. Five working groups were organized, one to develop broad project selection and evaluation criteria and four to focus on specific contaminant problems. A Coordinating Group comprised of working group spokesmen and federal and state representatives, was set up to plan and organize the routine functioning of these working groups. The working groups were charged with defining particular contaminant problems; identifying shortcomings in technology development, stakeholder involvement, regulatory review, and commercialization which impede the resolution of these problems; and identifying candidate sites or technologies which could serve as regional innovative demonstration projects to test new approaches to overcome the shortcomings. This report from the Coordinating Group to the DOIT Committee highlights the key findings and opportunities uncovered by these fact-finding working groups. It provides a basis from which recommendations from the DOIT Committee to the federal government can be made. It also includes observations from two public roundtables, one on commercialization and another on regulatory and institutional barriers impeding technology development and cleanup.

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

    EPA Science Inventory

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

  16. On a new coordinate system with astrophysical application: Spiral coordinates

    NASA Astrophysics Data System (ADS)

    Campos, L. M. B. C.; Gil, P. J. S.

    In this presentation are introduced spiral coordinates, which are a particular case of conformal coordinates, i.e. orthogonal curvelinear coordinates with equal factors along all coordinate axis. The spiral coordinates in the plane have as coordinate curves two families of logarithmic spirals, making a constant angle, respectively phi and pi / 2-phi, with all radial lines, where phi is a parameter. They can be obtained from a complex function, representing a spiral potential flow, due to the superposition of a source/sink with a vortex; the parameter phi in this case specifies the ratio of the ass flux of source/sink to the circulation of the vortex. Regardless of hydrodynamical or other interpretations, spiral coordinates are particulary convenient in situation where physical quantities vary only along a logarithmicspiral. The example chosen is the propagation of Alfven waves along a logarithmic spiral, as an approximation to Parker's spiral. The equation of dissipative MHD are written in spiral coordinates, and eliminated to specify the Alfven wave equation in spiral coordinates; the latter is solved exactly in terms of Bessel functions, and the results analyzed for values of the parameters corresponding to the solar wind.

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

    PubMed

    Lange, Linda; Heisel, Stefan; Sadowski, Gabriele

    2016-01-01

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

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

    SciTech Connect

    Fondeur, F; Samuel Fink, S

    2006-03-07

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

  19. Solvent effects in polyelectrolyte adsorption: Computer simulations with explicit and implicit solvent

    NASA Astrophysics Data System (ADS)

    Reddy, Govardhan; Yethiraj, Arun

    2010-02-01

    The adsorption of strongly charged polyelectrolyte chains to an oppositely charged planar surface is studied using computer simulation. In addition to an explicit solvent model, two implicit solvent models are considered: one where the solvent induces an implicit Lennard-Jones (ILJ) interaction between polymer sites and one where the solvent induces a many body interaction that depends on the solvent accessible surface area (SASA) of the monomers. Molecular and Brownian dynamics simulations are reported for the explicit and implicit solvent models, respectively. All three models give similar results for the adsorption of the chains in good solvent. The electrostatic attraction between the surface and the polymers is not sufficient to drive the strong adsorption that is seen in experiments. In poor solvents, the models give different results for the adsorption excess and the mechanism for polyelectrolyte adsorption. With explicit solvent, thick adsorbed layers are formed at both charged and neutral surfaces. With the SASA model, adsorbed layers are formed on the charged but not on the neutral surface. With the ILJ model, adsorbed layers are not formed on any surfaces. The results show that the solvent plays a dominant role in the adsorption of polyelectrolytes under poor solvent conditions and that many-body solvent effects have a qualitative effect on the adsorption characteristics and mechanism. In particular, SASA and depletion effects could possibly play an important role; the former can be incorporated in the SASA model, but the latter cannot. The results suggest that accurate computational models for polymer adsorption under poor solvent conditions must incorporate the solvent explicitly.

  20. Classical field approach to quantum weak measurements.

    PubMed

    Dressel, Justin; Bliokh, Konstantin Y; Nori, Franco

    2014-03-21

    By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field. PMID:24702338

  1. Solvent fermentations of pulp streams and their constituents

    SciTech Connect

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

    1984-01-01

    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.

  2. 78 FR 73819 - Forest Resource Coordinating Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-09

    ... Forest Service Forest Resource Coordinating Committee AGENCY: Forest Service, USDA. ACTION: Notice of...-18, 2013 meeting of the Forest Resource Coordinating Committee due to the Government partial shutdown... INFORMATION CONTACT: Maya Solomon, Forest Resource Coordinating Committee Program Coordinator; by phone...

  3. Computing free energies of protein conformations from explicit solvent simulations

    PubMed Central

    Zhuravlev, Pavel I.; Wu, Sangwook; Potoyan, Davit A.; Rubinstein, Michael; Papoian, Garegin A.

    2016-01-01

    We report a fully general technique addressing a long standing challenge of calculating conformational free energy differences between various states of a polymer chain from simulations using explicit solvent force fields. The main feature of our method is a special mapping variable, a path coordinate, which continuously connects two conformations. The path variable has been designed to preserve locality in the phase space near the path endpoints. We avoid the problem of sampling the unfolded states by creating an artificial confinement “tube” in the phase space that prevents the molecule from unfolding without affecting the calculation of the desired free energy difference. We applied our technique to compute the free energy difference between two native-like conformations of the small protein Trp-cage using the CHARMM force field with explicit solvent. We verified this result by comparing it with an independent, significantly more expensive calculation. Overall, the present study suggests that the new method of computing free energy differences between polymer chain conformations is accurate and highly computationally efficient. PMID:20493264

  4. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart IIII of Part 63 Protection of Environment ENVIRONMENTAL... of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  5. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 6 Table 6 to Subpart KKKK of Part 63 Protection of Environment ENVIRONMENTAL... Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation data....

  6. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart IIII of Part 63 Protection of Environment ENVIRONMENTAL... of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  7. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart RRRR of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  8. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 6 Table 6 to Subpart KKKK of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  9. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart RRRR of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  10. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart QQQQ of Part 63 Protection of Environment ENVIRONMENTAL... HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  11. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart NNNN of Part 63 Protection of Environment ENVIRONMENTAL... Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation data....

  12. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart MMMM of Part 63 Protection of Environment ENVIRONMENTAL... MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  13. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart IIII of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  14. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart MMMM of Part 63 Protection of Environment ENVIRONMENTAL... MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  15. 40 CFR Table 5 to Subpart Vvvv of... - Default Organic HAP Contents of Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart VVVV of Part 63 Protection of Environment ENVIRONMENTAL... Contents of Solvents and Solvent Blends As specified in § 63.5758(a)(6), when detailed organic HAP content data for solvent blends are not available, you may use the values in the following table:...

  16. 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

    ... Solvents and Solvent Blends 4 Table 4 to Subpart OOOO of Part 63 Protection of Environment ENVIRONMENTAL... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  17. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart IIII of Part 63 Protection of Environment ENVIRONMENTAL... of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  18. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart PPPP of Part 63 Protection of Environment ENVIRONMENTAL... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  19. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart PPPP of Part 63 Protection of Environment ENVIRONMENTAL... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  20. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart MMMM of Part 63 Protection of Environment ENVIRONMENTAL... Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  1. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart QQQQ of Part 63 Protection of Environment ENVIRONMENTAL...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  2. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart NNNN of Part 63 Protection of Environment ENVIRONMENTAL...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart RRRR of Part 63 Protection of Environment ENVIRONMENTAL... Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation data:...

  4. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart PPPP of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  5. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart PPPP of Part 63 Protection of Environment ENVIRONMENTAL... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  6. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 4 Table 4 to Subpart OOOO of Part 63 Protection of Environment ENVIRONMENTAL... OOOO of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  7. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart NNNN of Part 63 Protection of Environment ENVIRONMENTAL...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  8. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart QQQQ of Part 63 Protection of Environment ENVIRONMENTAL...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  9. 40 CFR Table 5 to Subpart Vvvv of... - Default Organic HAP Contents of Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart VVVV of Part 63 Protection of Environment ENVIRONMENTAL... Contents of Solvents and Solvent Blends As specified in § 63.5758(a)(6), when detailed organic HAP content data for solvent blends are not available, you may use the values in the following table:...

  10. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart QQQQ of Part 63 Protection of Environment ENVIRONMENTAL...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  11. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart RRRR of Part 63 Protection of Environment ENVIRONMENTAL... Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation data:...

  12. 40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart PPPP of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  13. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 6 Table 6 to Subpart KKKK of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  14. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Solvents and Solvent Blends 6 Table 6 to Subpart KKKK of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  15. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart MMMM of Part 63 Protection of Environment ENVIRONMENTAL... Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  16. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 4 Table 4 to Subpart OOOO of Part 63 Protection of Environment ENVIRONMENTAL... OOOO of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  17. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart NNNN of Part 63 Protection of Environment ENVIRONMENTAL... Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation data....

  18. 40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart NNNN of Part 63 Protection of Environment ENVIRONMENTAL...—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  19. 40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart QQQQ of Part 63 Protection of Environment ENVIRONMENTAL... HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  20. 40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart MMMM of Part 63 Protection of Environment ENVIRONMENTAL... MMMM of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  1. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Solvents and Solvent Blends 4 Table 4 to Subpart OOOO of Part 63 Protection of Environment ENVIRONMENTAL... OOOO of Part 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data...

  2. 40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 6 Table 6 to Subpart KKKK of Part 63 Protection of Environment ENVIRONMENTAL... Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation data....

  3. 40 CFR Table 4 to Subpart Oooo of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Solvents and Solvent Blends 4 Table 4 to Subpart OOOO of Part 63 Protection of Environment ENVIRONMENTAL... 63—Default Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or...

  4. 40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart IIII of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  5. 40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 3 Table 3 to Subpart RRRR of Part 63 Protection of Environment ENVIRONMENTAL... Organic HAP Mass Fraction for Solvents and Solvent Blends You may use the mass fraction values in the following table for solvent blends for which you do not have test data or manufacturer's formulation...

  6. 40 CFR Table 5 to Subpart Vvvv of... - Default Organic HAP Contents of Solvents and Solvent Blends

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Solvents and Solvent Blends 5 Table 5 to Subpart VVVV of Part 63 Protection of Environment ENVIRONMENTAL... Contents of Solvents and Solvent Blends As specified in § 63.5758(a)(6), when detailed organic HAP content data for solvent blends are not available, you may use the values in the following table:...

  7. Instrumental systematics and weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Mandelbaum, R.

    2015-05-01

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

  8. Spin effects in the weak interaction

    SciTech Connect

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

    1990-01-01

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

  9. Rheology of weakly vibrated granular materials

    NASA Astrophysics Data System (ADS)

    Dijksman, J. A.; Wortel, G.; van Hecke, M.

    2009-06-01

    We show how weak vibrations substantially modify the rheology of granular materials. We experimentally probe dry granular flows in a weakly vibrated split bottom shear cell—the weak vibrations modulate gravity and act as an agitation source. By tuning the applied stress and vibration strength, and monitoring the resulting strain as a function of time, we uncover a rich phase diagram in which non-trivial transitions separate a jammed phase, a creep flow case, and a steady flow case.

  10. Auditory dysfunction associated with solvent exposure

    PubMed Central

    2013-01-01

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

  11. Environmental Impacts on Nuclear Reprocessing Solvents

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  12. Organic Solvent Tolerant Lipases and Applications

    PubMed Central

    Kanwar, Shamsher S.

    2014-01-01

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

  13. Differential response of marine diatoms to solvents

    SciTech Connect

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

    1995-06-01

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

  14. Solvent Effect on the Photolysis of Riboflavin.

    PubMed

    Ahmad, Iqbal; Anwar, Zubair; Ahmed, Sofia; Sheraz, Muhammad Ali; Bano, Raheela; Hafeez, Ambreen

    2015-10-01

    The kinetics of photolysis of riboflavin (RF) in water (pH 7.0) and in organic solvents (acetonitrile, methanol, ethanol, 1-propanol, 1-butanol, ethyl acetate) has been studied using a multicomponent spectrometric method for the assay of RF and its major photoproducts, formylmethylflavin and lumichrome. The apparent first-order rate constants (k obs) for the reaction range from 3.19 (ethyl acetate) to 4.61 × 10(-3) min(-1) (water). The values of k obs have been found to be a linear function of solvent dielectric constant implying the participation of a dipolar intermediate along the reaction pathway. The degradation of this intermediate is promoted by the polarity of the medium. This indicates a greater stabilization of the excited-triplet states of RF with an increase in solvent polarity to facilitate its reduction. The rate constants for the reaction show a linear relation with the solvent acceptor number indicating the degree of solute-solvent interaction in different solvents. It would depend on the electron-donating capacity of RF molecule in organic solvents. The values of k obs are inversely proportional to the viscosity of the medium as a result of diffusion-controlled processes. PMID:25698084

  15. Effect of Ligand Structural Isomerism in Formation of Calcium Coordination Networks

    SciTech Connect

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

    2012-03-28

    Using different structural isomers (2,5-; 2,4-; 2;6-; 3,4-; 3,5-) of pyridinedicarboxylic acid, nine calcium-based coordination networks were synthesized under hydro-/solvothermal conditions and/or were produced via solvent recrystallization of previously synthesized compounds. The coordination networks reported were characterized using single crystal X-ray diffraction and thermal methods. They show diverse structural topologies, depending on the ligand geometry and coordinated solvent molecules, with inorganic connectivity motifs ranging from isolated octahedra to infinite chains, layer and a three-dimensional dense framework. The as-synthesized and desolvated networks further show structural transformation to hydrated phases through dissolution/reformation pathways. The process is likely driven by the high hydration energy of the calcium metal center.

  16. Effect of solvent characteristics on coal liquefaction

    SciTech Connect

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

    1996-12-31

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

  17. 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...

  18. Exploring Hamiltonian dielectric solvent molecular dynamics

    NASA Astrophysics Data System (ADS)

    Bauer, Sebastian; Tavan, Paul; Mathias, Gerald

    2014-09-01

    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 α-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.

  19. Cleaning solvent substitution in electronic assemblies

    SciTech Connect

    Meier, G.J.

    1993-09-01

    Alternatives to chlorinated and fluorinated solvents have been identified, qualified, and implemented into production of complex electronic assemblies. Extensive compatibility studies were performed with components, piece-parts, and materials. Electrical testing and accelerated aging were used to screen for detrimental, long-term effects. A terpene, d-limonene, has been selected as the solvent of choice for cleaning complex electronic assemblies, and has been found to be compatible with the components and materials tested. A brief history of the overall project will be presented, along with representative cleaning efficiency results, compatibility results, and residual solvent data.

  20. Switchable solvents and methods of use thereof

    SciTech Connect

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

    2014-04-29

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

  1. Switchable solvents and methods of use thereof

    DOEpatents

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

    2011-07-19

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

  2. Switchable solvents and methods of use thereof

    DOEpatents

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

    2013-08-20

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

  3. What makes critical-solvent processes work

    SciTech Connect

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

    1984-06-01

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

  4. Coal liquefaction with coal tar solvent

    SciTech Connect

    Gir, S.; Rhodes, D.E.

    1986-12-16

    A method is described of liquefying coal, comprising: mixing solid coal with a process solvent comprising coal tar material which has been at least partially hydrogenated under conditions which selectively hydrogenate aromatic coal tar components to hydroaromatics and which preserve the integrity of organonitrogen coal tar components, to produce a coal-solvent slurry; treating the coal-solvent slurry under coal-liquefying conditions in a liquefaction zone to produce a solution containing coal liquefaction products; and recovering coal liquefaction products from the solution.

  5. Genomic and Genetic Approaches to Solvent Tolerance

    SciTech Connect

    Eleftherios T. Papoutsakis

    2005-06-10

    The proposed research is to understand and exploit the molecular basis that determines tolerance of the industrially important anaerobic clostridia to solvents. Furthermore, we aim to develop general genomic and metabolic engineering strategies for understanding the molecular basis of tolerance to chemicals and for developing tolerant strains. Our hypothesis is that the molecular basis of what makes bacterial cells able to withstand high solvent concentrations can be used to metabolically engineer cells so that they can tolerate higher concentrations of solvents and related chemicals.

  6. Firing of pulverized solvent refined coal

    DOEpatents

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

    1990-05-15

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

  7. Hydrogenolysis in coal liquefaction and pyrolysis: the relative importance of solvent radicals and free hydrogen atoms

    SciTech Connect

    McMillen, D.F.; Malhotra, R.; Chang, S.J.; Nigenda, S.E.

    1985-01-01

    In this paper we wish to further support our contention that a significant part of the structural fragmentation occuring during coal liquefaction is not ''spontaneous'', but results from a previously undocumented fundamental reaction, '' radical-hydrogen-transfer'' (RHT), to aromatic positions bearing aliphatic (or ether) linkages in the coal structures (reaction 1). It is no longer at issue whether alternatives to thermal scission of inherently weak bonds exist under donor solvent coal liquefaction conditions: The observed cleavage of very strong alkyl-aryl bonds in hydroaromatic media, at 400C, in the absence of H2 pressure, on coal liquefaction time scales, (reaction 2) has demonstrated that what are formally defined as hydrogenolyses do take place under conditions where free hydrogen atoms have been thought to be unimportant. The fundamentally intriguing and possibly technologically important question that remains is whether or not this cleavage simply involves the ipso addition of free hydrogen atoms, and if does not, then by what mechanism does it take place. In order to help answer the above question, we wish to present results that (1) demonstrate the relative importance of free hydrogen atoms and solvent ''hydrogen-carrier radicals'' for bond scission in the donor solvent system most likely (of those systems generally studied) to generate ''free'' hydrogen atoms, and (2) suggest the relative importance of the two transfer modes for solvent systems that are much less likely to generate free hydrogen atoms (and not coincidentally are better coal liquefaction solvents). 16 refs., 1 tab.

  8. Future Coordinated Universal Time

    NASA Astrophysics Data System (ADS)

    McCarthy, Dennis D.

    Coordinated Universal Time (UTC), created by adjusting International Atomic Time (TAI) by the appropriate number of leap seconds, is the uniform time scale that is the basis of most civil timekeeping in the world. The concept of a leap second was introduced to ensure that UTC would not differ by more than 0.9 seconds from UT1, the time determined by the rotation of the Earth. The principal reason for this was to meet the requirements of celestial navigation. However, with the proliferation in the use of satellite navigation, it is appropriate to reconsider this historical position. In view of emerging problems with the current definition of UTC in navigation and communications, user dissatisfaction with leap seconds is beginning to surface. Even with accurate estimates of the deceleration of the Earth's rotation there remain significant variations in the Earth's rate of rotation, which prevent the prediction of leap seconds beyond a few months in advance. The inability to predict leap seconds coupled with the growing urgency for a uniform time scale without discontinuities make it appropriate to examine the future definition of UTC.

  9. Ulysses: UVCS Coordinated Observations

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    We present results from coordinated observations in which instruments on Solar and Heliospheric Observatory (SOHO) and Ulysses were used to measure the density and flow speed of plasma at the Sun and to again measure the same properties of essentially the same plasma in the solar wind. Plasma was sampled by Ultraviolet Coronagraph Spectrometer (UVCS) at 3.5 and 4.5 solar radii and by Ulysses/SWOOPS at 5 AU. Data were acquired during a nearly 2 week period in May-June 1997 at a latitude of 9-10 degrees north of the equator, on the east limb and, hence, in the streamer belt and the source location of slow wind. Density and outflow speed are compared, in order to check for preservation of the near Sun characteristics in the interplanetary medium. By chance, Ulysses was at the very northern edge of the visible streamer belt. Nevertheless, no evidence of fast wind, or mixing with fast wind coming from the northern polar coronal hole, was evident at Ulysses. The morphology of the streamer belt was similar at the beginning and end of the observation period, but was markedly different during the middle of the period. A corresponding change in density (but not flow speed) was noted at Ulysses.

  10. Flexoelectricity via coordinate transformations

    NASA Astrophysics Data System (ADS)

    Stengel, Massimiliano

    2014-03-01

    Flexoelectricity describes the electric polarization that is linearly induced by a strain gradient, and is being intensely investigated as a tantalizing new route to converting mechanical stimulation into electrical signals and vice versa. While several breakthough experiments have been reported in the past few years, progress on the theoretical front has been comparatively slow, especially in the context of first-principles electronic-structure theory. The main difficulty with calculating the flexoelectric response of a material is the inherent breakdown of translational periodicity that a strain gradient entails, which at first sight questions the very applicability of traditional plane-wave pseudopotential methods. In this talk I will show how these obstacles can be overcome by combining density-functional perturbation theory with generalized coordinate transformations, gaining access to the full microscopic response (in terms of electronic charge density, polarization and atomic displacements) of a crystal or nanostructure to an arbitrary deformation field. As a practical demonstration, I will present results on the full flexoelectric response of a SrTiO3 film, including atomic relaxations and surface effects.

  11. Fault zone fabric and fault weakness.

    PubMed

    Collettini, Cristiano; Niemeijer, Andr; Viti, Cecilia; Marone, Chris

    2009-12-17

    Geological and geophysical evidence suggests that some crustal faults are weak compared to laboratory measurements of frictional strength. Explanations for fault weakness include the presence of weak minerals, high fluid pressures within the fault core and dynamic processes such as normal stress reduction, acoustic fluidization or extreme weakening at high slip velocity. Dynamic weakening mechanisms can explain some observations; however, creep and aseismic slip are thought to occur on weak faults, and quasi-static weakening mechanisms are required to initiate frictional slip on mis-oriented faults, at high angles to the tectonic stress field. Moreover, the maintenance of high fluid pressures requires specialized conditions and weak mineral phases are not present in sufficient abundance to satisfy weak fault models, so weak faults remain largely unexplained. Here we provide laboratory evidence for a brittle, frictional weakening mechanism based on common fault zone fabrics. We report on the frictional strength of intact fault rocks sheared in their in situ geometry. Samples with well-developed foliation are extremely weak compared to their powdered equivalents. Micro- and nano-structural studies show that frictional sliding occurs along very fine-grained foliations composed of phyllosilicates (talc and smectite). When the same rocks are powdered, frictional strength is high, consistent with cataclastic processes. Our data show that fault weakness can occur in cases where weak mineral phases constitute only a small percentage of the total fault rock and that low friction results from slip on a network of weak phyllosilicate-rich surfaces that define the rock fabric. The widespread documentation of foliated fault rocks along mature faults in different tectonic settings and from many different protoliths suggests that this mechanism could be a viable explanation for fault weakening in the brittle crust. PMID:20016599

  12. The Neural Network In Coordinate Transformation

    NASA Astrophysics Data System (ADS)

    Urusan, Ahmet Yucel

    2011-12-01

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

  13. Evaluating the dynamics and electrostatic interactions of folded proteins in implicit solvents.

    PubMed

    Hua, Duy P; Huang, He; Roy, Amitava; Post, Carol Beth

    2016-01-01

    Three implicit solvent models, namely GBMVII, FACTS, and SCPISM, were evaluated for their abilities to emulate an explicit solvent environment by comparing the simulated conformational ensembles, dynamics, and electrostatic interactions of the Src SH2 domain and the Lyn kinase domain. This assessment in terms of structural features in folded proteins expands upon the use of hydration energy as a metric for comparison. All-against-all rms coordinate deviation, average positional fluctuations, and ion-pair distance distribution were used to compare the implicit solvent models with the TIP3P explicit solvent model. Our study shows that the Src SH2 domains solvated with TIP3P, GBMVII, and FACTS sample similar global conformations. Additionally, the Src SH2 ion-pair distance distributions of solvent-exposed side chains corresponding to TIP3P, GBMVII, and FACTS do not differ substantially, indicating that GBMVII and FACTS are capable of modeling these electrostatic interactions. The ion-pair distance distributions of SCPISM are distinct from others, demonstrating that these electrostatic interactions are not adequately reproduced with the SCPISM model. On the other hand, for the Lyn kinase domain, a non-globular protein with bilobal structure and a large concavity on the surface, implicit solvent does not accurately model solvation to faithfully reproduce partially buried electrostatic interactions and lobe-lobe conformations. Our work reveals that local structure and dynamics of small, globular proteins are modeled well using FACTS and GBMVII. Nonetheless, global conformations and electrostatic interactions in concavities of multi-lobal proteins resulting from simulations with implicit solvent models do not match those obtained from explicit water simulations. PMID:26189497

  14. Derivation of Reliable Geometries in QM Calculations of DNA Structures: Explicit Solvent QM/MM and Restrained Implicit Solvent QM Optimizations of G-Quadruplexes.

    PubMed

    Gkionis, Konstantinos; Kruse, Holger; Šponer, Jiří

    2016-04-12

    Modern dispersion-corrected DFT methods have made it possible to perform reliable QM studies on complete nucleic acid (NA) building blocks having hundreds of atoms. Such calculations, although still limited to investigations of potential energy surfaces, enhance the portfolio of computational methods applicable to NAs and offer considerably more accurate intrinsic descriptions of NAs than standard MM. However, in practice such calculations are hampered by the use of implicit solvent environments and truncation of the systems. Conventional QM optimizations are spoiled by spurious intramolecular interactions and severe structural deformations. Here we compare two approaches designed to suppress such artifacts: partially restrained continuum solvent QM and explicit solvent QM/MM optimizations. We report geometry relaxations of a set of diverse double-quartet guanine quadruplex (GQ) DNA stems. Both methods provide neat structures without major artifacts. However, each one also has distinct weaknesses. In restrained optimizations, all errors in the target geometries (i.e., low-resolution X-ray and NMR structures) are transferred to the optimized geometries. In QM/MM, the initial solvent configuration causes some heterogeneity in the geometries. Nevertheless, both approaches represent a decisive step forward compared to conventional optimizations. We refine earlier computations that revealed sizable differences in the relative energies of GQ stems computed with AMBER MM and QM. We also explore the dependence of the QM/MM results on the applied computational protocol. PMID:26914292

  15. 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...

  16. Theory of solvent influence on reaction dynamics.

    PubMed

    Neufeld, A A

    2005-04-22

    A generalization of the recently published quantum-classical approximation [A. A. Neufeld, J. Chem. Phys., 119, 2488 (2003)] for the purposes of reaction dynamics in condensed phase is presented. The obtained kinetic equations treat a solvent influence in a nonphenomenological way, account for the change of the free energy of the surrounding media, allow for different solvent dynamics in each reaction channel, and constitute a powerful framework for an accurate modeling of solvent effects, including ultrafast processes. The key features of the approach are its differential form, which considerably facilitates practical applications, and well defined wide applicability limits. The developed methodology fully accounts for an arbitrary long memory of the canonical bath and covers solvent-induced processes from a subpicosecond time scale. PMID:15945675

  17. [Shoe factory workers, solvents and health].

    PubMed

    Foà, Vito; Martinotti, Irene

    2012-01-01

    Exposure to organic solvents in footwear manufacturing industry came from the glues used adhering the shoe parts to each other. Benzene was the first solvent used in shoe factories until the evidence of its capacity to cause leukaemia. Then, the demonstration that exposure to n-hexane was related to distal polyneuropathy limited the use of this substance. After that, results of neurotoxicological studies conducted on workers exposed to different mixtures of organic solvents make necessary prevention measure directed to a progressive reduction of air dispersion of these chemicals. Today exposure to solvents in workplaces is regulated by health based exposure limit values that should warranty absence of central nervous system effects. One of the most important rules of occupational medicine is verify that these exposure levels are really health protective also for workers with increased susceptibility. PMID:22697025

  18. Biological monitoring of chlorinated hydrocarbon solvents

    SciTech Connect

    Monster, A.C.

    1986-08-01

    The possibility of biological monitoring of exposure to some volatile, halogenated hydrocarbons will be discussed. Most of these agents are widely used as solvents. All agents act on the nervous system as narcotics and differ widely in toxicity. Most of the solvents undergo biotransformation to metabolites. This allows biological assessment of exposure by measurement of the solvent and/or metabolites in exhaled air, blood, and/or urine. However, the same metabolites may occur with exposure to different chlorinated hydrocarbons, eg, trichloroethanol and trichloroacetic acid from exposure to trichloroethene, tetrachloroethene, and 1,1,1-trichloroethane. On the other hand, these agents differ widely in the percentage that is metabolized. There are large gaps in our knowledge, however, and much research will have to be carried out before even tentative data can be established for most of the solvents.

  19. Innovative Technologies for Chlorinated Solvent Remediation

    NASA Astrophysics Data System (ADS)

    Pennell, Kurt D.; Cápiro, Natalie L.

    2014-07-01

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

  20. Volatile Solvent Use among Western Australian Adolescents.

    ERIC Educational Resources Information Center

    Carroll, Annemaree; Houghton, Stephen; Odgers, Peta

    1998-01-01

    Semistructured interviews were conducted with 40 adolescents who reported inhaling volatile solvents. All were aware of the short-term health risks involved in use, and most reported experiencing ill effects. Offers suggestions for intervention. (Author/GCP)

  1. Implicit solvent methods for free energy estimation

    PubMed Central

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

    2014-01-01

    Solvation is a fundamental contribution in many biological processes and especially in molecular binding. Its estimation can be performed by means of several computational approaches. The aim of this review is to give an overview of existing theories and methods to estimate solvent effects giving a specific focus on the category of implicit solvent models and their use in Molecular Dynamics. In many of these models, the solvent is considered as a continuum homogenous medium, while the solute can be represented at the atomic detail and at different levels of theory. Despite their degree of approximation, implicit methods are still widely employed due to their trade-off between accuracy and efficiency. Their derivation is rooted in the statistical mechanics and integral equations disciplines, some of the related details being provided here. Finally, methods that combine implicit solvent models and molecular dynamics simulation, are briefly described. PMID:25193298

  2. SOLVENT-FREE ORGANIC SYNTHESES USING MICROWAVES

    EPA Science Inventory

    An expeditious solvent-free approach for organic synthesis is described which involves simple exposure of neat reactants to microwave (MW) irradiation. A variety of cleavage, condensation, cyclization, oxidation and reduction reactions will be presented including the efficient o...

  3. United States Air Force Wipe Solvent Testing

    NASA Technical Reports Server (NTRS)

    Hornung, Steven D.; Beeson, Harold D.

    2000-01-01

    The Wright-Patterson Air Force Base (WPAFB), as part of the Air Force Material Command, requested that NASA Johnson Space Center (JSC) White Sands Test Facility (WSTF) conduct testing and analyses in support of the United States Air Force Wipe Solvent Development Project. The purpose of the wipe solvent project is to develop an alternative to be used by Air Force flight line and maintenance personnel for the wipe cleaning of oxygen equipment. This report provides material compatibility, liquid oxygen (LOX) mechanical impact, autogenous ignition temperature (AIT), and gauge cleaning test data for some of the currently available solvents that may be used to replace CFC-113 and methyl chloroform. It provides data from previous WSTF test programs sponsored by the Naval Sea Systems Command, the Kennedy Space Center, and other NASA programs for the purpose of assisting WP AFB in identifying the best alternative solvents for validation testing.

  4. Wetting of polymers by their solvents.

    PubMed

    Lequeux, François; Talini, Laurence; Verneuil, Emilie; Delannoy, Guillaume; Valois, Pauline

    2016-02-01

    We review the studies on the wetting of soluble polymeric substrates by their solvents, both in the literature and conducted in our group in the past decade. When a droplet of solvent spreads on a soluble polymer layer, its wetting angle can strongly vary with the contact line velocity even at capillary numbers smaller than unity, in contrast to non-soluble substrates. The solvent content in the polymer is a key parameter for the spreading dynamics; that content is set by the initial conditions, but also by the transfers occurring from the droplet to the polymer layer during spreading. We focus on hydrophilic amorphous polymers that are glassy at room temperature, and we discuss the consequences on wetting of the very large changes in the polymer physical properties induced by solvent sorption. We finally present new results on polymers of varying molar masses, and show how they open new perspectives for a better understanding of powder dissolution. PMID:26920515

  5. Weak rigidity in the PPN formalism

    SciTech Connect

    del Olmo, V.; Olivert, J.

    1987-04-01

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

  6. Staggering towards a calculation of weak amplitudes

    SciTech Connect

    Sharpe, S.R.

    1988-09-01

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

  7. On modeling weak sinks in MODPATH.

    PubMed

    Abrams, Daniel; Haitjema, H; Kauffman, L

    2013-01-01

    Regional groundwater flow systems often contain both strong sinks and weak sinks. A strong sink extracts water from the entire aquifer depth, while a weak sink lets some water pass underneath or over the actual sink. The numerical groundwater flow model MODFLOW may allow a sink cell to act as a strong or weak sink, hence extracting all water that enters the cell or allowing some of that water to pass. A physical strong sink can be modeled by either a strong sink cell or a weak sink cell, with the latter generally occurring in low-resolution models. Likewise, a physical weak sink may also be represented by either type of sink cell. The representation of weak sinks in the particle tracing code MODPATH is more equivocal than in MODFLOW. With the appropriate parameterization of MODPATH, particle traces and their associated travel times to weak sink streams can be modeled with adequate accuracy, even in single layer models. Weak sink well cells, on the other hand, require special measures as proposed in the literature to generate correct particle traces and individual travel times and hence capture zones. We found that the transit time distributions for well water generally do not require special measures provided aquifer properties are locally homogeneous and the well draws water from the entire aquifer depth, an important observation for determining the response of a well to non-point contaminant inputs. PMID:23025655

  8. CP Violation, Neutral Currents, and Weak Equivalence

    DOE R&D Accomplishments Database

    Fitch, V. L.

    1972-03-23

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

  9. Newtonian and relativistic emission coordinates

    SciTech Connect

    Coll, Bartolome; Ferrando, Joan Josep; Morales-Lladosa, Juan Antonio

    2009-09-15

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

  10. Fuzzy coordinator in control problems

    NASA Technical Reports Server (NTRS)

    Rueda, A.; Pedrycz, W.

    1992-01-01

    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.

  11. 75 FR 55947 - Coordinated Communications

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-15

    ... coordination with a candidate, a candidate's authorized political committee, or political party committee... FR 53893 (Oct. 21, 2009). The NPRM comment period closed on January 19, 2010. The Commission received... Proposed Rulemaking on Coordinated Communications, 75 FR 6590 (Feb. 10, 2010). The SNPRM invited...

  12. Coordination challenges for autonomous spacecraft

    NASA Technical Reports Server (NTRS)

    Clement, B. J.; Barrett, A.

    2002-01-01

    While past flight projects involved a single spacecraft in isolation, over forty proposed future missions involve multiple coordinated spacecraft. This paper presents characteristics of such missions in terms of properties of the phenomena being measured as well as the rationale for using multiple spacecraft. We describe the coordination problems associated with operating these missions and identify needed technologies.

  13. Coordinated Transportation: Problems and Promise?

    ERIC Educational Resources Information Center

    Fickes, Michael

    1998-01-01

    Examines the legal, administrative, and logistical barriers that have prevented the wide acceptance of coordinating community and school transportation services and why these barriers may be breaking down. Two examples of successful implementation of coordinated transportation are examined: employing a single system to serve all transportation…

  14. Coordinate-Free Rotation Operator.

    ERIC Educational Resources Information Center

    Leubner, C.

    1979-01-01

    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)

  15. Drift Hamiltonian in magnetic coordinates

    SciTech Connect

    White, R.B.; Boozer, A.H.; Hay, R.

    1982-02-01

    A Hamiltonian formulation of the guiding-center drift in arbitrary, steady state, magnetic and electric fields is given. The canonical variables of this formulation are simply related to the magnetic coordinates. The modifications required to treat ergodic magnetic fields using magnetic coordinates are explicitly given in the Hamiltonian formulation.

  16. Health sector development: from aid coordination to resource management.

    PubMed

    Walt, G; Pavignani, E; Gilson, L; Buse, K

    1999-09-01

    Aid coordination has assumed a prominent place on health policy agendas. This paper synthesizes the findings of research undertaken to explore the changing practices of aid coordination across a number of countries. It begins by reviewing the key issues giving rise to increased attention to aid coordination in the health sector. The second section describes, assesses and compares the strengths and weaknesses of the dominant mechanisms or instruments which were found to be employed to coordinate health sector aid in the case studies. From this analysis, four factors become clear. First, in many countries, coordination mechanisms have been introduced as a part of an incremental process of trying out different approaches--there is no one model that stands out at any one time. Secondly, some instruments function largely for consultation, predominantly coordinating inputs, while others are more directive and operational, and are used to manage inputs, processes and outputs. Third, many of the mechanisms have not excelled, although, fourth, it is difficult to judge the effectiveness or impact of aid coordination. It is therefore argued that concern with the effectiveness of aid coordination arrangements must give way to a broader analysis of the processes, outputs and outcomes governing the use of both external and domestic resources, focusing on institutional characteristics, the distribution and nature of influence among the actors, and the interests which they pursue through the aid regime. These factors varied considerably across the countries indicating that aid management is context dependent and subject to continuing changes. Finally, the paper looks at the findings in the light of the introduction of sector-wide approaches. PMID:10621238

  17. Method of stripping metals from organic solvents

    DOEpatents

    Todd, Terry A.; Law, Jack D.; Herbst, R. Scott; Romanovskiy, Valeriy N.; Smirnov, Igor V.; Babain, Vasily A.; Esimantovski, Vyatcheslav M.

    2009-02-24

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

  18. Biofiltration of solvent vapors from air

    SciTech Connect

    Oh, Young-sook.

    1993-01-01

    For various industrial solvent vapors, biofiltration promises to offer a cost-effective emission control technology. Exploiting the full potential of this technology will help attain the goals of the Clean Air Act Amendments of 1990. Concentrating on large volumes of volatile industrial solvents, stable multicomponent microbial enrichments capable of growing a mineral medium with solvent vapors as their only source of carbon and energy were obtained from soil and sewage sludge. These consortia were immobilized on an optimized porous solid support (ground peat moss and perlite). The biofilter material was packed in glass columns connected to an array of pumps and flow meters that allowed the independent variation of superficial velocity and solvent vapor concentrations. In various experiments, single solvents, such as methanol, butanol, acetonitrile, hexane and nitrobenzene, and solvent mixtures, such as benzene-toluene-xylene (BTX) and chlorobenzene-o-dichlorobenzene (CB/DCB) were biofiltered with rates ranging from 15 to334 g solvent removed per m[sup 3] filter volume /h. Pressure drops were low to moderate (0-10 mmHg/m) and with periodic replacement of moisture, the biofiltration activity could be maintained for a period of several months. The experimental data on methanol biofiltration were subjected to mathematical analysis and modeling by the group of Dr. Baltzis at NJIT for a better understanding and a possible scale up of solvent vapor biofilters. In the case of chlorobenzenes and nitrobenzene, the biofilter columns had to be operated with water recirculation in a trickling filter mode. To prevent inactivation of the trickling filter by acidity during CB/DCB removal, pH control was necessary, and the removal rate of CB/DCB was strongly influenced by the flow rate of the recyling water. Nitrobenzene removal in a trickling filter did not require pH control, since the nitro group was reduced and volatilized as ammonia.

  19. Hydrogen recovery by novel solvent systems

    SciTech Connect

    Shinnar, R.; Ludmer, Z.; Ullmann, A.

    1991-08-01

    The objective of this work is to develop a novel method for purification of hydrogen from coal-derived synthesis gas. The study involved a search for suitable mixtures of solvents for their ability to separate hydrogen from the coal derived gas stream in significant concentration near their critical point of miscibility. The properties of solvent pairs identified were investigated in more detail to provide data necessary for economic evaluation and process development.

  20. Water as a Solvent for Life

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Pratt, Lawrence R.

    2015-01-01

    "Follow the water" is our basic strategy in searching for life in the universe. The universality of water as the solvent for living systems is usually justified by arguing that water supports the rich organic chemistry that seeds life, but alternative chemistries are possible in other organic solvents. Here, other, essential criteria for life that have not been sufficiently considered so far, will be discussed.

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

    DOEpatents

    Garg, Diwakar; Givens, Edwin N.; Schweighardt, Frank K.

    1984-01-01

    A process is disclosed for the solvent refining of non-anthracitic coal at elevated temperatures and pressure in a hydrogen atmosphere using a hydrocarbon solvent which before being recycled in the solvent refining process is subjected to chemical treatment to extract substantially all nitrogenous and phenolic constituents from the solvent so as to improve the conversion of coal and the production of oil in the solvent refining process. The solvent refining process can be either thermal or catalytic. The extraction of nitrogenous compounds can be performed by acid contact such as hydrogen chloride or fluoride treatment, while phenolic extraction can be performed by caustic contact or contact with a mixture of silica and alumina.

  2. Persisting weakness after withdrawal of a statin.

    PubMed

    Mygland, Åse; Ljøstad, Unn; Krossnes, Bård Kronen

    2014-01-01

    An 81-year-old woman treated with simvastatin for several years followed by atorvastatin for about 1 year presented with fatigue, weakness and unsteady gait. The finding of elevated creatine kinase (CK) and symmetric muscle weakness around shoulders and hips led to suspicion of a toxic statin-associated myopathy. Atorvastatin was withdrawn, but her weakness persisted. Owing to persisting weakness, an autoimmune myopathy (myositis) was suspected, but initially disregarded since a muscle biopsy showed necrotic muscle fibres without inflammatory cell infiltrates and myositis-specific autoantibodies were absent. After 18 months with slowly progressive weakness and increasing CK values, awareness of new knowledge about autoimmunity as a cause of necrotic myopathy, led to a successful treatment trial with intravenous immunoglobulines, followed by steroids and metothrexate. Antibodies to the target enzyme of statins (HMGCR (3-hydroksy-3-methylglutaryl-coenzyme A reductase)) were detected in her serum, and she was diagnosed with autoimmune necrotic myositis probably triggered by atorvastatin. PMID:24713712

  3. Maximal Holevo Quantity Based on Weak Measurements

    PubMed Central

    Wang, Yao-Kun; Fei, Shao-Ming; Wang, Zhi-Xi; Cao, Jun-Peng; Fan, Heng

    2015-01-01

    The Holevo bound is a keystone in many applications of quantum information theory. We propose “ maximal Holevo quantity for weak measurements” as the generalization of the maximal Holevo quantity which is defined by the optimal projective measurements. The scenarios that weak measurements is necessary are that only the weak measurements can be performed because for example the system is macroscopic or that one intentionally tries to do so such that the disturbance on the measured system can be controlled for example in quantum key distribution protocols. We evaluate systematically the maximal Holevo quantity for weak measurements for Bell-diagonal states and find a series of results. Furthermore, we find that weak measurements can be realized by noise and project measurements. PMID:26090962

  4. Solvent dependent photophysical properties of dimethoxy curcumin

    NASA Astrophysics Data System (ADS)

    Barik, Atanu; Indira Priyadarsini, K.

    2013-03-01

    Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (Δf), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (ϕf) and fluorescence lifetime (τf) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ϕf increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.

  5. Solvent Extraction and Ion Exchange in Radiochemistry

    NASA Astrophysics Data System (ADS)

    Skarnemark, G.

    In 1805, Bucholz extracted uranium from a nitric acid solution into ether and back-extracted it into pure water. This is probably the first reported solvent-extraction investigation. During the following decades, the distribution of neutral compounds between aqueous phases and pure solvents was studied, e.g., by Peligot, Berthelot and Jungfleisch, and Nernst. Selective extractants for analytical purposes became available during the first decades of the twentieth century. From about 1940, extractants such as organophosphorous esters and amines were developed for use in the nuclear fuel cycle. This connection between radiochemistry and solvent-extraction chemistry made radiochemists heavily involved in the development of new solvent extraction processes, and eventually solvent extraction became a major separation technique in radiochemistry. About 160 years ago, Thompson and Way observed that soil can remove potassium and ammonium ions from an aqueous solution and release calcium ions. This is probably the first scientific report on an ion-exchange separation. The first synthesis of the type of organic ion exchangers that are used today was performed by Adams and Holmes in 1935. Since then, ion-exchange techniques have been used extensively for separations of various radionuclides in trace as well as macro amounts. During the last 4 decades, inorganic ion exchangers have also found a variety of applications. Today, solvent extraction as well as ion exchange are used extensively in the nuclear industry and for nuclear, chemical, and medical research. Some of these applications are discussed in the chapter.

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

    SciTech Connect

    Delmau, L.H.

    2002-10-08

    This work was undertaken to optimize the solvent used in the Caustic Side Solvent Extraction (CSSX) process and to measure key chemical and physical properties related to its performance in the removal of cesium from the alkaline high-level salt waste stored in tanks at the Savannah River Site. The need to adjust the solvent composition arose from the prior discovery that the previous baseline solvent was supersaturated with respect to the calixarene extractant. The following solvent-component concentrations in Isopar{reg_sign} L diluent are recommended: 0.007 M calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) extractant, 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) phase modifier, and 0.003 M tri-n-octylamine (TOA) stripping aid. Criteria for this selection included BOBCalixC6 solubility, batch cesium distribution ratios (D{sub Cs}), calculated flowsheet robustness, third-phase formation, coalescence rate (dispersion numbers), and solvent density. Although minor compromises within acceptable limits were made in flowsheet robustness and solvent density, significant benefits were gained in lower risk of third-phase formation and lower solvent cost. Data are also reported for the optimized solvent regarding the temperature dependence of D{sub Cs} in extraction, scrubbing, and stripping (ESS); ESS performance on recycle; partitioning of BOBCalixC6, Cs-7SB, and TOA to aqueous process solutions; partitioning of organic anions; distribution of metals; solvent phase separation at low temperatures; solvent stability to elevated temperatures; and solvent density and viscosity. Overall, the technical risk of the CSSX process has been reduced by resolving previously identified issues and raising no new issues.

  7. Origin of weak magnetism in compounds with cubic laves structure.

    PubMed

    Torun, E; Janner, A; de Groot, R A

    2016-02-17

    The origin of the weak itinerant magnetism in materials such as TiBe2 and ZrZn2 is investigated. The huge peak in the density of states at the Fermi energy is attributed to a special symmetry of the C15 structure: no crystal field splitting of the d levels occurs in the case of coordination by spherical ligands. Crystal field splitting is also investigated for the f orbitals in C15 structures such as PuZn2 and ThMg2. It is observed that the situation in f levels is more complicated than the d levels because the characteristics of the crystal field splitting for f levels does not only depend on the the local point symmetry of the compounds. PMID:26795899

  8. Nonlinear response of a linear chain to weak driving

    NASA Astrophysics Data System (ADS)

    Hennig, D.; Mulhern, C.; Burbanks, A. D.; Schimansky-Geier, L.

    2014-01-01

    We study the escape of a chain of coupled units over the barrier of a metastable potential. It is demonstrated that a very weak external driving field with a suitably chosen frequency suffices to accomplish speedy escape. The latter requires passage through a transition state, the formation of which is triggered by permanent feeding of energy from a phonon background into humps of localized energy and elastic interaction of the arising breather solutions. In fact, cooperativity between the units of the chain entailing coordinated energy transfer is shown to be crucial for enhancing the rate of escape in an extremely effective and low-energy cost way where the effects of entropic localization and breather coalescence conspire.

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

    SciTech Connect

    Fondeur, F.; Fink, S.

    2011-12-08

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

  10. Stability of the Caustic-Side Solvent Extraction (CSSX) Process Solvent: Effect of High Nitrite on Solvent Nitration

    SciTech Connect

    Bonnesen, P.V.

    2002-06-26

    The purpose of this investigation was to determine whether nitrated organic compounds could be formed during operation of the Caustic-Side Solvent Extraction (CSSX) process, and whether such compounds would present a safety concern. The CSSX process was developed to remove cesium from alkaline high-level salt waste stored at the US Department of Energy Savannah River Site (SRS). The solvent is composed of the cesium extractant calix[4]arene-bis-(4-tert-octylbenzo-crown-6) (BOBCalixC6), a fluorinated alcohol phase modifier, tri-n-octylamine (TOA), and an isoparaffinic diluent (Iospar{reg_sign}). During the CSSX process, the solvent is expected to be exposed to high concentrations of nitrate and nitrite dissolved in the alkaline waste feed. The solvent will also be exposed to dilute (50 mM) nitric acid solutions containing low concentrations of nitrite during scrubbing, followed by stripping with 1 mM nitric acid. The solvent is expected to last for one year of plant operation, and the temperatures the solvent may experience during the process could range from as low as 15 C to as high as 35 C. Excursions from standard process conditions could result in the solvent experiencing higher temperatures, as well as concentrations of nitrate, nitrite, and most importantly nitric acid, that exceed normal operating conditions. Accordingly, conditions may exist where nitration reactions involving the solvent components, possibly leading to other chemical reactions stemming from nitration reactions, could occur. To model such nitration reactions, the solvent was exposed to the types of nitrate- and nitrite-containing solutions that might be expected to be encountered during the process (even under off-normal conditions), as a function of time, temperature, and concentration of nitrate, nitrite, and nitric acid. The experiments conducted as part of this report were designed to examine the more specific effect that high nitrite concentrations could have on forming nitrated organics. The present set of results supplement those obtained from earlier experiments conducted in FY 2001 in which nitration effects due to nitric acid alone and an average nitrite-containing alkaline simulant were examined.

  11. Keep meaning in conversational coordination

    PubMed Central

    Cuffari, Elena C.

    2014-01-01

    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

  12. Occupational exposure to solvents and male infertility

    PubMed Central

    Cherry, N; Labreche, F; Collins, J; Tulandi, T

    2001-01-01

    OBJECTIVES—To determine whether, in a case-referent study of infertility patients, cases with low motile sperm count were more likely than referents to have had exposure to organic solvents.
METHODS—Occupations of men attending fertility clinics in Canada were assigned codes reflecting probable exposure to organic solvents, at four grades of intensity, using a job exposure matrix previously developed. A case referent design was used, with cases being defined as men with <12×106/ml motile sperm. Information from 656 men in manual work attending a single clinic in Montreal in 1972-91 was used for the main study. A separate analysis was conducted with information for 574 men in manual work attending 10 further clinics across Canada in 1984-7.
RESULTS—In the Montreal series a significant association was found between intensity of exposure to solvents and clinical findings of <12×106/ml motile sperm. Odds ratios (ORs), after allowing for confounding, were 2.07 (95% confidence interval (95% CI) 1.24 to 3.44) for moderate exposure to solvents and 3.83 (95% CI 1.37 to 10.65) for high exposure. In the second series of 568 men, the effect was confirmed at high exposure to solvents (OR 2.90, 95% CI 1.01 to 8.34) but not at moderate exposure (OR 1.01, 95% CI 0.53 to 1.92).
CONCLUSIONS—Exposure to organic solvents is common both at work and in recreational pursuits. The results of this study suggest that efforts should be made to identify the compounds hazardous to male fertility, and if the risk is confirmed, to regulate their use.


Keywords: infertility; solvents; male manual workers PMID:11555684

  13. Quantum correlation cost of the weak measurement

    SciTech Connect

    Zhang, Jun; Wu, Shao-xiong; Yu, Chang-shui

    2014-12-15

    Quantum correlation cost (QCC) characterizing how much quantum correlation is used in a weak-measurement process is presented based on the trace norm. It is shown that the QCC is related to the trace-norm-based quantum discord (TQD) by only a factor that is determined by the strength of the weak measurement, so it only catches partial quantumness of a quantum system compared with the TQD. We also find that the residual quantumness can be ‘extracted’ not only by the further von Neumann measurement, but also by a sequence of infinitesimal weak measurements. As an example, we demonstrate our outcomes by the Bell-diagonal state.

  14. Weak side of strong topological insulators

    NASA Astrophysics Data System (ADS)

    Sbierski, Björn; Schneider, Martin; Brouwer, Piet W.

    2016-04-01

    Strong topological insulators may have nonzero weak indices. The nonzero weak indices allow for the existence of topologically protected helical states along line defects of the lattice. If the lattice admits line defects that connect opposite surfaces of a slab of such a "weak-and-strong" topological insulator, these states effectively connect the surface states at opposite surfaces. Depending on the phases accumulated along the dislocation lines, this connection results in a suppression of in-plane transport and the opening of a spectral gap or in an enhanced density of states and an increased conductivity.

  15. Weak gauge boson radiation in parton showers

    NASA Astrophysics Data System (ADS)

    Christiansen, Jesper R.; Sjöstrand, Torbjörn

    2014-04-01

    The emission of W and Z gauge bosons off quarks is included in a traditional QCD + QED shower. The unitarity of the shower algorithm links the real radiation of the weak gauge bosons to the negative weak virtual corrections. The shower evolution process leads to a competition between QCD, QED and weak radiation, and allows for W and Z boson production inside jets. Various effects on LHC physics are studied, both at low and high transverse momenta, and effects at higher-energy hadron colliders are outlined.

  16. Coordination polymers of uranium(IV) terephthalates.

    PubMed

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

    2015-02-14

    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

  17. Weak-field general relativistic dynamics and the Newtonian limit

    NASA Astrophysics Data System (ADS)

    Cooperstock, F. I.

    2016-01-01

    We show that the generally held view that the gravity of weak-field nonrelativistic-velocity sources being invariably almost equivalent to Newtonian gravity (NG) (the “Newtonian limit” approach) is in some instances misleading and in other cases incorrect. A particularly transparent example is provided by comparing the Newtonian and general relativistic analyses of a simple variant of van Stockum’s infinite rotating dust cylinder. We show that some very recent criticisms of our work that had been motivated by the Newtonian limit approach were incorrect and note that no specific errors in our work were found in the critique. In the process, we underline some problems that arise from inappropriate coordinate transformations. As further support for our methodology, we note that our weak-field general relativistic treatment of a model galaxy was vindicated recently by the observations of Xu et al. regarding our prediction that the Milky Way was 19-21 kpc in radius as opposed to the commonly held view that the radius was 15 kpc.

  18. Spontaneous vesicle formation in a deep eutectic solvent.

    PubMed

    Bryant, Saffron J; Atkin, Rob; Warr, Gregory G

    2016-02-14

    Solvent penetration experiments and small-angle X-ray scattering reveal that phospholipids dissolved in a deep eutectic solvent (DES) spontaneously self-assemble into vesicles above the lipid chain melting temperature. This means DESs are one of the few nonaqueous solvents that mediate amphiphile self-assembly, joining a select set of H-bonding molecular solvents and ionic liquids. PMID:26701210

  19. Coordination polymers from a highly flexible alkyldiamine-derived ligand: structure, magnetism and gas adsorption studies.

    PubMed

    Hawes, Chris S; Chilton, Nicholas F; Moubaraki, Boujemaa; Knowles, Gregory P; Chaffee, Alan L; Murray, Keith S; Batten, Stuart R; Turner, David R

    2015-10-28

    The synthesis and structural, magnetic and gas adsorption properties of a series of coordination polymer materials prepared from a new, highly flexible and internally functional tetrakis-carboxybenzyl ligand H4L derived from 1,2-diaminoethane have been examined. The compound poly-[Ni3(HL)2(OH2)4]·2DMF·2H2O 1, a two-dimensional coordination polymer, contains aqua- and carboxylato-bridged trinuclear Ni(II) clusters, the magnetic behaviour of which can be well described through experimental fitting and ab initio modelling to a ferromagnetically coupled trimer with a positive axial zero-field splitting parameter D. Compound poly-[Zn2L]·2DMF·3H2O 2, a three-dimensional coordination polymer displaying frl topology, contains large and well-defined solvent channels, which are shown to collapse on solvent exchange or drying. Compound poly-[Zn2(L)(DMSO)4]·3DMSO·3H2O 3, a highly solvated two-dimensional coordination polymer, displayed poor stability characteristics, however a structurally related material poly-[Zn2(L)(bpe)(DMSO)2]·DMSO·3H2O 4 was prepared under similar synthetic conditions by including the 1,2-bis(4-pyridyl)ethylene bpe co-ligand. Compound 4, containing small one-dimensional solvent channels, shows excellent structural resilience to solvent exchange and evacuation, and the evacuated material displays selective adsorption of CO2 over N2 at 273 K in the pressure range 0-1 atm. Each of the coordination polymers displays subtle differences in the conformation and binding mode of the ligand species, with switching between two distinct conformers (X-shaped and H-shaped), as well as a variable protonation state of the central core, with significant effects on the resulting network structures and physical properties of the materials. PMID:26223788

  20. Solvent gating of intramolecular electron transfer

    SciTech Connect

    Miller, R.M. ); Spears, K.G.; Gong, J.H.; Wach, M. )

    1994-02-03

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

  1. Non-aqueous cleaning solvent substitution

    SciTech Connect

    Meier, G.J.

    1994-01-01

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

  2. Non-aqueous cleaning solvent substitution

    NASA Technical Reports Server (NTRS)

    Meier, Gerald J.

    1994-01-01

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

  3. Solvent System Selection Strategies in Countercurrent Separation.

    PubMed

    Liu, Yang; Friesen, J Brent; McAlpine, James B; Pauli, Guido F

    2015-11-01

    The majority of applications in countercurrent and centrifugal partition chromatography, collectively known as countercurrent separation, are dedicated to medicinal plant and natural product research. In countercurrent separation, the selection of the appropriate solvent system is of utmost importance as it is the equivalent to the simultaneous choice of column and eluent in liquid chromatography. However, solvent system selection is often laborious, involving extensive partition and/or analytical trials. Therefore, simplified solvent system selection strategies that predict the partition coefficients and, thus, analyte behavior are in high demand and may advance both the science of countercurrent separation and its applications. The last decade of solvent system selection theory and applications are critically reviewed, and strategies are classified according to their data input requirements. This offers the practitioner an up-to-date overview of rationales and methods for choosing an efficient solvent system, provides a perspective regarding their accuracy, reliability, and practicality, and discusses the possibility of combining multiple methods for enhanced prediction power. PMID:26393937

  4. Competition between weak localization and ballistic transport.

    PubMed

    Tian, Chushun

    2009-06-19

    High-frequency transport in perfect periodic dielectric cylinder arrays is studied. We analytically calculate the diffusive-ballistic transport crossover, which displays the competition between weak localization and ballistic transport. PMID:19659008

  5. Sodium in weak G-band giants

    NASA Technical Reports Server (NTRS)

    Drake, Jeremy J.; Lambert, David L.

    1994-01-01

    Sodium abundances have been determined for eight weak G-band giants whose atmospheres are greatly enriched with products of the CN-cycling H-burning reactions. Systematic errors are minimized by comparing the weak G-band giants to a sample of similar but normal giants. If, further, Ca is selected as a reference element, model atmosphere-related errors should largely be removed. For the weak-G-band stars (Na/Ca) = 0.16 +/- 0.01, which is just possibly greater than the result (Na/Ca) = 0.10 /- 0.03 from the normal giants. This result demonstrates that the atmospheres of the weak G-band giants are not seriously contaminated with products of ON cycling.

  6. Reversing entanglement change by a weak measurement

    SciTech Connect

    Sun Qingqing; Zubairy, M. Suhail; Al-Amri, M.; Davidovich, Luiz

    2010-11-15

    Entanglement of a system changes due to interactions with the environment. A typical type of interaction is amplitude damping. If we add a detector to monitor the environment and only select the no-damping outcome, this amplitude damping is modified into a weak measurement. Here we show that the entanglement change of a two-qubit state due to amplitude damping or weak measurement can be probabilistically reversed. For the amplitude-damping case, the entanglement partially recovers under most conditions. For the weak-measurement case, the recovery of the initial entangled state is exact. The reversal procedure involves another weak measurement, preceded and followed by bit flips applied to both qubits. We propose a linear optics scheme for the experimental demonstration of these procedures.

  7. Towards ultra-fast solvent evaporation, the development of a computer controlled solvent vapor annealing chamber

    NASA Astrophysics Data System (ADS)

    Nelson, Gunnar; Wong, J.; Drapes, C.; Grant, M.; Baruth, A.

    Despite the promise of cheap and fast nanoscale ordering of block polymer thin films via solvent vapor annealing, a standardized, scalable production scheme remains elusive. Solvent vapor annealing exposes a nano-thin film to the vapors of one or more solvents with the goal of forming a swollen and mobile state to direct the self-assembly process by tuning surface energies and mediating unfavorable chain interactions. We have shown that optimized annealing conditions, where kinetic and thermal properties for crystal growth are extremely fast (<1s), exist at solvent concentrations just below the order-disorder transition of the film. However, when investigating the propagation of a given morphology into the bulk of a film during drying, the role of solvent evaporation comes under great scrutiny. During this process, the film undergoes a competition between two fronts; phase separation and kinetic trapping. Recent results in both theory and experiment point toward this critical element in controlling the resultant morphologies; however, no current method includes a controllable solvent evaporation rate at ultra-fast time scales. We report on a computer-controlled, pneumatically actuated chamber that provides control over solvent evaporation down to 15 ms. Furthermore, in situ spectral reflectance monitors solvent concentration with 10 ms temporal resolution and reveals several possible evaporation trajectories, ranging from linear to exponential to logarithmic. Funded by Dr. Randolph Ferlic Summer Research Scholarship and NASA Nebraska Space Grant.

  8. Changes in psychological performances of solvent-poisoned and solvent-exposed workers

    SciTech Connect

    Lindstroem, K.

    1980-01-01

    The changes in psychological performances associated with long-term exposure to organic solvents and solvent mixtures were studied in a group of 56 male workers diagnosed as having an occupational disease caused by solvents. Their mean duration of exposure was 9.1 +/- SD 8.3 years, and they were exposed mainly to halogenated and aromatic hydrocarbons and to mixtures of paint solvents. The psychological performances of these solvent-exposed patients were compared with those of 98 styrene-exposed workers and a nonexposed group of 43 construction workers. The applied psychological test variables were factor analyzed, before other statistical analysis, in order to clarify what they measured in the present study. The solvent-exposed group was characterized by a decline in visuomotor performance and decreased freedom from distractibility. The poor visuomotor performances were also related to the long duration of solvent exposure in this group of patients. The index applied for the exposure level revealed no significant relationships to psychological performances among the solvent-exposed patients. The psychological performances of the styrene-exposed group differed only very slightly from those of the nonexposed workers.

  9. Solvent/non-solvent sintering: a novel route to create porous microsphere scaffolds for tissue regeneration.

    PubMed

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

    2008-08-01

    Solvent/non-solvent sintering creates porous polymeric microsphere scaffolds suitable for tissue engineering purposes with control over the resulting porosity, average pore diameter, and mechanical properties. Five different biodegradable biocompatible polyphosphazenes exhibiting glass transition temperatures from -8 to 41 degrees C and poly (lactide-co-glycolide), (PLAGA) a degradable polymer used in a number of biomedical settings, were examined to study the versatility of the process and benchmark the process to heat sintering. Parameters such as: solvent/non-solvent sintering solution composition and submersion time effect the sintering process. PLAGA microsphere scaffolds fabricated with solvent/non-solvent sintering exhibited an interconnected porosity and pore size of 31.9% and 179.1 mum, respectively which was analogous to that of conventional heat sintered PLAGA microsphere scaffolds. Biodegradable polyphosphazene microsphere scaffolds exhibited a maximum interconnected porosity of 37.6% and a maximum compressive modulus of 94.3 MPa. Solvent/non-solvent sintering is an effective strategy for sintering polymeric microspheres, with a broad spectrum of glass transition temperatures, under ambient conditions making it an excellent fabrication route for developing tissue engineering scaffolds and drug delivery vehicles. PMID:18161819

  10. Solvent/Non-Solvent Sintering: A Novel Route to Create Porous Microsphere Scaffolds For Tissue Regeneration

    PubMed Central

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

    2009-01-01

    Solvent/non-solvent sintering creates porous polymeric microsphere scaffolds suitable for tissue engineering purposes with control over the resulting porosity, average pore diameter and mechanical properties. Five different biodegradable biocompatible polyphosphazenes exhibiting glass transition temperatures from −8°C to 41oC and poly(lactide-co-glycolide), (PLAGA) a degradable polymer used in a number of biomedical settings, were examined to study the versatility of the process and benchmark the process to heat sintering. Parameters such as: solvent/non-solvent sintering solution composition and submersion time effect the sintering process. PLAGA microsphere scaffolds fabricated with solvent/non-solvent sintering exhibited an interconnected porosity and pore size of 31.9% and 179.1µm respectively which was analogous to that of conventional heat sintered PLAGA microsphere scaffolds. Biodegradable polyphosphazene microsphere scaffolds exhibited a maximum interconnected porosity of 37.6% and a maximum compressive modulus of 94.3MPa. Solvent/non-solvent sintering is an effective strategy for sintering polymeric microspheres, with a broad spectrum of glass transition temperatures, under ambient conditions making it an excellent fabrication route for developing tissue engineering scaffolds and drug delivery vehicles. PMID:18161819

  11. Coordinated action in multiteam systems.

    PubMed

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

    2012-07-01

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

  12. Markov Tracking for Agent Coordination

    NASA Technical Reports Server (NTRS)

    Washington, Richard; Lau, Sonie (Technical Monitor)

    1998-01-01

    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.

  13. Chlorinated solvent replacements recycle/recovery review report

    SciTech Connect

    Beal, M.; Hsu, D.; McAtee, R.E.; Weidner, J.R. ); Berg, L.; McCandless, F.P.; Waltari, S.; Peterson, C. . Dept. of Chemical Engineering)

    1992-08-01

    This report is a literature review of waste solvents recycle/recovery methods and shows the results of solvent separations using membrane and distillation technologies. The experimental solvent recovery methods were conducted on solvent replacements for chlorinated solvents at Montana State University. The literature review covers waste solvents separation using distillation, membranes decantation, filtration, carbon adsorption, solvent extraction, and other vapor-phase separation techniques. The results of this study identify solvent distillation methods as the most common separation technique. The alternative separation methods typically supplement distillation. The study shows the need for industries to identify waste solvent disposal methods and investigate the economics of waste solvent recycling as a possible waste reduction method.

  14. Electromagnetic and Weak transitions in light nuclei

    SciTech Connect

    M. Viviani; L.E. Marcucci; A. Kievsky; S. Rosati; R. Schiavilla

    2002-09-01

    Recent advances in the study of the p -- d radiative and mu -- {sup 3}He weak capture processes by our group are presented and discussed. The trinucleon bound and scattering states have been obtained from variational calculations by expanding the corresponding wave functions in terms of correlated hyper-spherical harmonic functions. The electromagnetic and weak transition currents include one- and two-body operators. The accuracy achieved in these calculations allows for interesting comparisons with experimental data.

  15. Elastic scattering with weakly bound projectiles

    SciTech Connect

    Figueira, J. M.; Abriola, D.; Arazi, A.; Capurro, O. A.; Marti, G. V.; Martinez Heinmann, D.; Pacheco, A. J.; Testoni, J. E.; Barbara, E. de; Fernandez Niello, J. O.; Padron, I.; Gomes, P. R. S.; Lubian, J.

    2007-02-12

    Possible effects of the break-up channel on the elastic scattering threshold anomaly has been investigated. We used the weakly bound 6,7Li nuclei, which is known to undergo break-up, as projectiles in order to study the elastic scattering on a 27Al target. In this contribution we present preliminary results of these experiments, which were analyzed in terms of the Optical Model and compared with other elastic scattering data using weakly bound nuclei as projectile.

  16. Looking for heavier weak bosons with DUMAND

    NASA Technical Reports Server (NTRS)

    Brown, R. W.; Stecker, F. W.

    1980-01-01

    One or more heavier weak bosons may coexist with the standard weak boson, a broad program may be laid out for a search for the heavier W's via change in the total cross section due to the additional propagator, a concomitant search, and a subsequent search for significant antimatter in the universe involving the same annihilation, but being independent of possible neutrino oscillations. The program is likely to require detectors sensitive to higher energies, such as acoustic detectors.

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

    SciTech Connect

    Gloe, Karsten; Tasker, Peter A; Oshima, Tatsuya; Watarai, Hitoshi; Nilsson, Mikael

    2013-01-01

    Preface The theme of supramolecular chemistry (SC), entailing the organization of multiple species through noncovalent interactions, has permeated virtually all aspects of chemical endeavor over the past several decades. Given that the observed behavior of discrete molecular species depends upon their weak interactions with one another and with matrix components, one would have to conclude that SC must indeed form part of the fabric of chemistry itself. A vast literature now serves to categorize SC phenomena within a body of consistent terminology. The word supramolecular itself appears in the titles of dozens of books, several journals, and a dedicated encyclopedia. Not surprisingly, the theme of SC also permeates the field of solvent extraction (SX), inspiring the framework for this volume of Ion Exchange and Solvent Extraction. It is attempted in the six chapters of this volume to identify both how supramolecular behavior occurs and is studied in the context of SX and how SC is influencing the current direction of SX. Researchers and practitioners have long dealt with supramolecular interactions in SX. Indeed, the use of polar extractant molecules in nonpolar media virtually assures that aggregative interactions will dominate the solution behavior of SX. Analytical chemists working in the 1930s to the 1950s with simple mono- and bidentate chelating ligands as extractants noted that extraction of metal ions obeyed complicated mass-action equilibria involving complex stoichiometries. As chemists and engineers developed processes for nuclear and hydrometallurgical applications in the 1950s and 1960s, the preference for aliphatic diluents only enhanced the complexity and supramolecular nature of extraction chemistry. Use of physical techniques such as light scattering and vapor-pressure measurements together with various spectroscopic methods revealed organic-phase aggregates from well-defined dimers to small aggregates containing a few extractant molecules to large 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 and how it is used generally in design of novel SX reagents. Major approaches using SC principles are outlined and illustrated. Chapter 2 expands upon the theme of ion-pair recognition and introduces outer-sphere recognition of metal complexes, a novel idea with the potential for structural control of solvation, casting a new light on solvent modifiers. Chapter 3 reviews the large literature of calixarenes as extraction reagents for metal ions, where the synthetic versatility of this family of compounds has produced vast possibilities for inclusion and selective separations. Chapter 4 extends such chemistry to extraction of biomolecules, where the potential for selective separations is only beginning to be explored through site recognition in macromolecules. In Chapter 5, a detailed examination of the liquid-liquid interface as an expression of supramolecular phenomena i...

  18. AXAF Coordinate Transformation at XRCF

    NASA Technical Reports Server (NTRS)

    He, Helen; McDowell, Jonathan; Conroy, Maureen

    1997-01-01

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

  19. Revised Coordinates for Apollo Hardware

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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.

  20. Chlorinated solvent releases to M-Area process sewers

    SciTech Connect

    Christensen, E.J.; Brendell, C.K.

    1981-12-18

    This report estimates the quantity of solvent released to the process sewers leading to the seepage basin and Tims Branch since M Area operations commenced in 1952. Arriving at an accurate quantitative assessment of degreaser solvent releases is difficult, since no measurements of solvent loss to the process sewers or annual use in M Area were ever made. As a result, solvent use and loss estimates are derived from past solvent purchase orders, past operational events and M-Area personnel experience.