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Sample records for diluted water solutions

  1. Thermodynamics of Dilute Solutions.

    ERIC Educational Resources Information Center

    Jancso, Gabor; Fenby, David V.

    1983-01-01

    Discusses principles and definitions related to the thermodynamics of dilute solutions. Topics considered include dilute solution, Gibbs-Duhem equation, reference systems (pure gases and gaseous mixtures, liquid mixtures, dilute solutions), real dilute solutions (focusing on solute and solvent), terminology, standard states, and reference systems.…

  2. Transport of water from concentrated to dilute solutions in cells of Nitella.

    PubMed

    OSTERHOUT, W J V

    1949-03-20

    The transport of water from concentrated to dilute solutions which occurs in the kidney and in a variety of living cells presents a problem of fundamental importance. If the cell acts as an osmometer we may expect to bring about such transport by creating an inwardly directed osmotic drive which is higher in one part of the cell than in other regions of the same cell. The osmotic drive is defined as the difference between internal and external osmotic pressure. Experiments with Nitella show that this expectation is justified. If water is placed at one end of the cell (A) and 0.4 M sucrose with an osmotic pressure of 11.2 atmospheres at the other end (B) water enters at A, passes along inside the cell, and escapes at B leaving behind at B the solutes which cannot pass out through the protoplasm. Hence the internal osmotic pressure becomes much higher at B than at A. When 0.4 M sucrose at B is replaced by 0.3 M sucrose with an osmotic pressure of 8.1 atmospheres we find that water enters at B, passes along inside the cell, and escapes at A so that water is transported from a concentrated to a dilute solution although the difference in osmotic pressure of the 2 solutions is more than 8 atmospheres. The solution at B thus becomes more concentrated. It is evident that if metabolism produces a higher osmotic pressure and consequently a higher inwardly directed osmotic drive in one region of the cell as compared with other parts of the same cell water may be transferred from a concentrated to a dilute solution so that the former solution becomes still more concentrated.

  3. Long-lived submicrometric bubbles in very diluted alkali halide water solutions.

    PubMed

    Duval, Eugène; Adichtchev, Sergey; Sirotkin, Sergey; Mermet, Alain

    2012-03-28

    Solutions of LiCl and of NaCl in ultrapure water were studied through Rayleigh/Brillouin scattering as a function of the concentration (molarity, M) of dissolved salt from 0.2 M to extremely low concentration (2 × 10(-17) M). The Landau-Placzek ratio, R/B, of the Rayleigh scattering intensity over the total Brillouin was measured thanks to the dynamically controlled stability of the used Fabry-Perot interferometer. It was observed that the R/B ratio follows two stages as a function of increasing dilution rate: after a strong decrease between 0.2 M and 2 × 10(-5) M, it increases to reach a maximum between 10(-9) M and 10(-16) M. The first stage corresponds to the decrease of the Rayleigh scattering by the ion concentration fluctuations with the decrease of salt concentration. The second stage, at lower concentrations, is consistent with the increase of the Rayleigh scattering by long-lived sub-microscopic bubbles with the decrease of ion concentration. The origin of these sub-microscopic bubbles is the shaking of the solutions, which was carried out after each centesimal dilution. The very long lifetime of the sub-microscopic bubbles and the effects of aging originate in the electric charge of bubbles. The increase of R/B with the decrease of the low salt concentration corresponds to the increase of the sub-microscopic bubble size with the decrease of concentration, which is imposed by the bubble stability due to the covering of the surface bubble by negative ions.

  4. Sulfuric Acid and Water: Paradoxes of Dilution

    ERIC Educational Resources Information Center

    Leenson, I. A.

    2004-01-01

    On equilibrium properties of aqueous solutions of sulfuric acid, Julius Thomsen has marked that the heat evolved on diluting liquid sulfuric acid with water is a continuous function of the water used, and excluded absolutely the acceptance of definite hydrates as existing in the solution. Information about thermochemical measurement, a discussion…

  5. Solubility of solutes in compressed gases: Dilute solution theory

    SciTech Connect

    Wang, X.; Tavlarides, L.L. . Dept. of Chemical Engineering)

    1994-03-01

    A dilute solution theory is developed for describing the thermodynamic behavior of a compressed gaseous dilute solution. The considerations follow generally accepted statistical treatments for describing dilute liquid solutions. The theory is self-consistent with the ideal gas law for dilute gases and with Henry's law for dilute liquid (or solid) solutions. Further, it provides a simple linear relationship which represents well the solubility behavior of a heavy solute (solid or liquid) in a gaseous solvent over relatively wide density regions of the solvent (i.e., 0 [le] [rho] [le] 2.0/V[sub c]).

  6. Osmosis is not driven by water dilution.

    PubMed

    Kramer, Eric M; Myers, David R

    2013-04-01

    There is a misconception among plant scientists that osmosis is driven by the tendency of solutes to dilute water. In this opinion article, we discuss the quantitative and qualitative failures of this view, and go on to review the correct kinetic picture of osmosis as it appears in physics textbooks.

  7. Neutron scattering study of dilute supercritical solutions

    NASA Astrophysics Data System (ADS)

    Cochran, H. D.; Wignall, G. D.; Shah, V. M.; Londono, J. D.; Bienkowski, P. R.

    Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope (sup 36)Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast.

  8. Neutron scattering study of dilute supercritical solutions

    SciTech Connect

    Cochran, H.D.; Wignall, G.D.; Shah, V.M.; Londono, J.D.; Bienkowski, P.R.

    1994-10-01

    Dilute solutions in supercritical solvents exhibit interesting microstructures that are related to their dramatic macroscopic behavior. In typical attractive solutions, solutes are believed to be surrounded by clusters of solvent molecules, and solute molecules are believed to congregate in the vicinity of one another. Repulsive solutions, on the other hand, exhibit a local region of reduced solvent density around the solute with solute-solute congregation. Such microstructures influence solubility, partial molar volume, reaction kinetics, and many other properties. We have undertaken to observe these interesting microstructures directly by neutron scattering experiments on dilute noble gas systems including Ar. The three partial structure factors for such systems and the corresponding pair correlation functions can be determined by using the isotope substitution technique. The systems studied are uniquely suited for our objectives because of the large coherent neutron scattering length of the isotope {sup 36}Ar and because of the accurate potential energy functions that are available for use in molecular simulations and theoretical calculations to be compared with the scattering results. We will describe our experiment, the unique apparatus we have built for it, and the neutron scattering results from our initial allocations of beam time. We will also describe planned scattering experiments to follow those with noble gases, including study of long-chain molecules in supercritical solvents. Such studies will involve hydrocarbon mixtures with and without deuteration to provide contrast.

  9. Separation and concentration of lower alcohols from dilute aqueous solutions

    DOEpatents

    Moore, Raymond H.; Eakin, David E.; Baker, Eddie G.; Hallen, Richard T.

    1991-01-01

    A process for producing, from a dilute aqueous solution of a lower (C.sub.1 -C.sub.5) alcohol, a concentrated liquid solution of the alcohol in an aromatic organic solvent is disclosed. Most of the water is removed from the dilute aqueous solution of alcohol by chilling sufficiently to form ice crystals. Simultaneously, the remaining liquid is extracted at substantially the same low temperature with a liquid organic solvent that is substantially immiscible in aqueous liquids and has an affinity for the alcohol at that temperature, causing the alcohol to transfer to the organic phase. After separating the organic liquid from the ice crystals, the organic liquid can be distilled to enrich the concentration of alcohol therein. Ethanol so separated from water and concentrated in an organic solvent such as toluene is useful as an anti-knock additive for gasoline.

  10. Reactions of recoil nitrogen-13 atoms in the ethanol-water system. Formation of [{sup 13}N]NH{sub 3} upon irradiation of water and dilute aqueous solutions of ethanol under a pressure of various gases

    SciTech Connect

    Korsakov, M.V.; Krasikova, R.N.; Fedorova, O.S.

    1995-07-01

    The influence of the nature and pressure of a gas (helium, hydrogen) contacting with a solution on radiochemical yield of the {sup 13}N-labeled products of nuclear-chemical and radiolytic reactions occurring upon irradiation of water and dilute aqueous solution of ethanol by 17-MeV protons was examined. It was shown that irradiation of water under hydrogen pressure, about 50% of recoil nitrogen-13 atoms are stabilized in the gas phase in the form of [{sup 13}N]N{sub 2}, and the main product in the liquid phase is ammonia-{sup 13}N.

  11. Terahertz absorption of dilute aqueous solutions

    NASA Astrophysics Data System (ADS)

    Heyden, Matthias; Tobias, Douglas J.; Matyushov, Dmitry V.

    2012-12-01

    Absorption of terahertz (THz) radiation by aqueous solutions of large solutes reports on the polarization response of their hydration shells. This is because the dipolar relaxation of the solute is dynamically frozen at these frequencies, and most of the solute-induced absorption changes, apart from the expulsion of water, are caused by interfacial water. We propose a model expressing the dipolar response of solutions in terms of a single parameter, the interface dipole moment induced in the interfacial water by electromagnetic radiation. We apply this concept to experimental THz absorption of hydrated sugars, amino acids, and proteins. None of the solutes studied here follow the expectations of dielectric theories, which predict a negative projection of the interface dipole on the external electric field. We find that this prediction is not able to describe the available experimental data, which instead suggests a nearly zero interface dipole for sugars and a more diverse pattern for amino acids. Hydrophobic amino acids, similarly to sugars, give rise to near zero interface dipoles, while strongly hydrophilic ones are best described by a positive projection of the interface dipole on the external field. The sign of the interface dipole is connected to the slope of the absorption coefficient with the solute concentration. A positive slope, implying an increase in the solution polarity relative to water, mirrors results frequently reported for protein solutions. We therefore use molecular dynamics simulations of hydrated glucose and lambda repressor protein to calculate the interface dipole moments of these solutes and the concentration dependence of the THz absorption. The absorption at THz frequencies increases with increasing solute concentration in both cases, implying a higher polarity of the solution compared to bulk water. The structure of the hydration layer, extracted from simulations, is qualitatively similar in both cases, with spatial correlations

  12. Terahertz absorption of dilute aqueous solutions.

    PubMed

    Heyden, Matthias; Tobias, Douglas J; Matyushov, Dmitry V

    2012-12-21

    Absorption of terahertz (THz) radiation by aqueous solutions of large solutes reports on the polarization response of their hydration shells. This is because the dipolar relaxation of the solute is dynamically frozen at these frequencies, and most of the solute-induced absorption changes, apart from the expulsion of water, are caused by interfacial water. We propose a model expressing the dipolar response of solutions in terms of a single parameter, the interface dipole moment induced in the interfacial water by electromagnetic radiation. We apply this concept to experimental THz absorption of hydrated sugars, amino acids, and proteins. None of the solutes studied here follow the expectations of dielectric theories, which predict a negative projection of the interface dipole on the external electric field. We find that this prediction is not able to describe the available experimental data, which instead suggests a nearly zero interface dipole for sugars and a more diverse pattern for amino acids. Hydrophobic amino acids, similarly to sugars, give rise to near zero interface dipoles, while strongly hydrophilic ones are best described by a positive projection of the interface dipole on the external field. The sign of the interface dipole is connected to the slope of the absorption coefficient with the solute concentration. A positive slope, implying an increase in the solution polarity relative to water, mirrors results frequently reported for protein solutions. We therefore use molecular dynamics simulations of hydrated glucose and lambda repressor protein to calculate the interface dipole moments of these solutes and the concentration dependence of the THz absorption. The absorption at THz frequencies increases with increasing solute concentration in both cases, implying a higher polarity of the solution compared to bulk water. The structure of the hydration layer, extracted from simulations, is qualitatively similar in both cases, with spatial correlations

  13. [Formation of oxalate in oxaliplatin injection diluted with infusion solutions].

    PubMed

    Eto, Seiji; Yamamoto, Kie; Shimazu, Kounosuke; Sugiura, Toshimune; Baba, Kaori; Sato, Ayaka; Goromaru, Takeshi; Hagiwara, Yoshiaki; Hara, Keiko; Shinohara, Yoshitake; Takahashi, Kojiro

    2014-01-01

    Oxaliplatin use can cause acute peripheral neuropathy characterized by sensory paresthesias, which are markedly exacerbated by exposure to cold temperatures, and is a dose-limiting factor in the treatment of colorectal cancer.Oxalate is eliminated in a series of nonenzymatic conversions of oxaliplatin in infusion solutions or biological fluids.Elimination of oxalate from oxaliplatin has been suggested as one of the reasons for the development of acute neuropathy.In this study, we developed a high-performance liquid chromatography(HPLC)-based method to detect oxalate formation, and investigated the time dependent formation of oxalate in oxaliplatin diluted with infusion solutions.The results obtained showed that the amount of oxalate in the solution corresponded to 1.6% of oxaliplatin 8 h after oxaliplatin dilution with a 5% glucose solution. On the other hand, oxalate formation from oxaliplatin diluted with a saline solution was ten-fold higher than that from oxaliplatin diluted with the 5% glucose solution.Most patients who were intravenously injected with oxaliplatin experienced venous pain.As a preventive measure against venous pain, dexamethasone was added to the oxaliplatin injection.We measured the amount of oxalate formed in the dexamethasone-containing oxaliplatin injection diluted with a 5% glucose solution.The amount of oxalate formed when dexamethasone was added did not differ significantly from that formed when dexamethasone was not added.Thus, there are no clinical problems associated with the stability of oxaliplatin solutions.

  14. Nematic ordering in dilute solutions of rodlike polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Potemkin, Igor I.; Khokhlov, Alexei R.

    2004-06-01

    Quantitative theory of orientational behavior of rodlike polyelectrolytes in dilute solution is developed. We find that in salt-free solutions many-body Coulomb interactions between macro- and counterions favor nematic ordering. It is shown that the orientationally isotropic phase of the solution becomes unstable toward nematic ordering at polymer concentration smaller than the overlap concentration. Our predictions are consistent with experimental observations for synthetic polyelectrolytes poly(p-phenylene)sulfonates in aqueous solutions.

  15. Dynamics of dilute solutions of poly(aspartic acid) and its sodium salt elucidated from atomistic molecular dynamics simulations with explicit water.

    PubMed

    Ramachandran, Sanoop; Katha, Anki Reddy; Kolake, Subramanya Mayya; Jung, Bokyung; Han, Sungsoo

    2013-11-01

    The use of forward osmosis (FO) process for seawater desalination has attracted tremendous interest in recent years. Besides the manufacture of suitable membranes, the major technical challenge in the efficient deployment of the FO technology lies in the development of a suitable "draw solute". Owing to its inherent advantages, poly(aspartic acid) has arisen to be an attractive candidate for this purpose. However, an investigation of its molecular level properties has not been studied in detail. In this paper, the dynamics of poly(aspartic acid) and its sodium salt in the dilute concentration regime have been reported. The quantification of the polymer conformational properties, its solvation behavior, and the counterion dynamics are studied. The neutral polymer shows a preferentially coiled structure whereas the fully ionized polymer has an extended structure. Upon comparing with poly(acrylic acid) polymer, another polymer which has been used as a draw solute, poly(aspartic acid) forms more number of hydrogen bonds as well as fewer ion pairs.

  16. Dynamics of dilute solutions of poly(aspartic acid) and its sodium salt elucidated from atomistic molecular dynamics simulations with explicit water.

    PubMed

    Ramachandran, Sanoop; Katha, Anki Reddy; Kolake, Subramanya Mayya; Jung, Bokyung; Han, Sungsoo

    2013-11-01

    The use of forward osmosis (FO) process for seawater desalination has attracted tremendous interest in recent years. Besides the manufacture of suitable membranes, the major technical challenge in the efficient deployment of the FO technology lies in the development of a suitable "draw solute". Owing to its inherent advantages, poly(aspartic acid) has arisen to be an attractive candidate for this purpose. However, an investigation of its molecular level properties has not been studied in detail. In this paper, the dynamics of poly(aspartic acid) and its sodium salt in the dilute concentration regime have been reported. The quantification of the polymer conformational properties, its solvation behavior, and the counterion dynamics are studied. The neutral polymer shows a preferentially coiled structure whereas the fully ionized polymer has an extended structure. Upon comparing with poly(acrylic acid) polymer, another polymer which has been used as a draw solute, poly(aspartic acid) forms more number of hydrogen bonds as well as fewer ion pairs. PMID:24099271

  17. Radiolysis of paracetamol in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Takács, Erzsébet; Wojnárovits, László

    2012-09-01

    Using radiolytic experiments hydroxyl radical (main reactant in advanced oxidation processes) was shown to effectively destroy paracetamol molecules. The basic reaction is attachment to the ring. The hydroxy-cyclohexadienyl radical produced in the further reactions may transform to hydroxylated paracetamol derivatives or to quinone type molecules and acetamide. The initial efficiency of aromatic ring destruction in the absence of dissolved O2 is c.a. 10%. The efficiency is 2-3 times higher in the presence of O2 due to its reaction with intermediate hydroxy-cyclohexadienyl radical and the subsequent ring destruction reactions through peroxi radical. Upon irradiation the toxicity of solutions at low doses increases with the dose and then at higher doses it decreases. This is due to formation of compounds with higher toxicity than paracetamol (e.g. acetamide, hidroquinone). These products, however, are highly sensitive to irradiation and degrade easily.

  18. Photodegradation of acetone in dilute aqueous solution

    SciTech Connect

    Stefan, M.I.; Bolton, J.R.

    1995-12-31

    Photochemical methods for destroying organic pollutants found in industrial wastewaters and groundwaters are being used successfully in environment treatment systems. This study focuses on acetone photodegradation in aqueous solution by UV irradiation (1 kW medium pressure Hg lamp) in the presence and absence of H{sub 2}O{sub 2}. Intermediates such as acetic and formic acids were detected. The kinetic data were evaluated and the reaction mechanisms were postulated considering the influence of oxygen concentration and pH. The generation of {sm_bullet}OH radicals from the photolysis of H{sub 2}O{sub 2} induces a faster decomposition of acetone (depending on H{sub 2}O{sub 2} concentration) than does direct photolysis.

  19. Electrolysis of dilute sodium chloride solution in a diaphragm cell

    SciTech Connect

    Kubasov, V.L.; Ivanter, I.A.; Druzhinin, E.A.; Vorob'eva, V.B.

    1986-02-10

    In some cases, as in the production of iodine and bromine, dilute solutions of sodium chloride remain unutilized. In view of the existence of large amounts of unutilized spent sodium chloride solutions and their harmful effect when discharged into the environment, it is desirable to develop a process for production of chlorine and alkali with high current efficiencies, satisfying industrial requirements, from dilute sodium chloride solutions. The authors have therefore studied electrolysis of solutions containing 160 and 180 kg/m/sup 3/ of sodium chloride, having pH of 11.0-11.5, close in composition to solutions from the Cheleken chemical factory. The chlorine and alkali current efficiencies and the compositions of the anolyte, catholyte, and anode gas were determined.

  20. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

    Bauman, A. J.; Weetal, H. H.; Weliky, N.

    1966-01-01

    Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

  1. Process of concentrating ethanol from dilute aqueous solutions thereof

    DOEpatents

    Oulman, C.S.; Chriswell, C.D.

    1981-07-07

    Relatively dilute aqueous solutions of ethanol are concentrated by passage through a bed of a crystalline silica polymorph, such as silicalite, to adsorb the ethanol with residual dilute feed in contact with the bed, which is displaced by passing concentrated aqueous ethanol through the bed without displacing the adsorbed ethanol. A product concentrate is then obtained by removing the adsorbed ethanol from the bed together with at least a portion of the concentrated aqueous ethanol used as the displacer liquid. This process permits ethanol to be concentrated from dilute fermentation beers, which may contain from 6 to 10% ethanol, to obtain a concentrate product at very low energy cost having an ethanol concentration in excess of 95%, such as a concentration of from 98 to 99.5%. 5 figs.

  2. Process of concentrating ethanol from dilute aqueous solutions thereof

    DOEpatents

    Oulman, Charles S. [Ames, IA; Chriswell, Colin D. [Slater, IA

    1981-07-07

    Relatively dilute aqueous solutions of ethanol are concentrated by passage through a bed of a crystalline silica polymorph, such as silicalite, to adsorb the ethanol with residual dilute feed in contact with the bed, which is displaced by passing concentrated aqueous ethanol through the bed without displacing the adsorbed ethanol. A product concentrate is then obtained by removing the adsorbed ethanol from the bed together with at least a portion of the concentrated aqueous ethanol used as the displacer liquid. This process permits ethanol to be concentrated from dilute fermentation beers, which may contain from 6 to 10% ethanol, to obtain a concentrate product at very low energy cost having an ethanol concentration in excess of 95%, such as a concentration of from 98 to 99.5%.

  3. Fluorescence and absorbance of polystyrene in dilute and semidilute solutions

    SciTech Connect

    Torkelson, J.M.; Lipsky, S.; Tirrell, M.; Tirrell, D.A.

    1983-02-01

    The fluorescence and absorbance of polystyrene in solution have been measured over a wide concentration range for several molecular weights and solvents (cyclohexane, 1,2 dichloroethane). The absorbance at wavelengths below 280 nm for these molecular weights and solvents is found to be insensitive to the transition between dilute and semidilute solutions. Self-absorption of the fluorescence results in a much reduced observed monomer emission at high concentration. When this is corrected, the ratio of excimer to monomer fluorescence intensity, I/sub E//I/sub M/, is essentially constant at low concentrations and at most increases only very slowly and smoothly at higher concentrations. No significant molecular weight or solvent effects on the concentration dependence of I/sub E//I/sub M/ are manifested for these molecular weights and solvents over the concentration range studied. Contrary to previous reports, fluorescence spectroscopy reveals no abrupt transition between dilute and semidilute solutions. 30 references, 6 figures, 4 tables.

  4. Coalescence of silver clusters by immersion in diluted HF solution

    SciTech Connect

    Milazzo, R. G.; Mio, A. M.; D’Arrigo, G.; Spinella, C.; Grimaldi, M. G.; Rimini, E.

    2015-07-14

    The galvanic displacement deposition of silver on H-terminated Si (100) in the time scale of seconds is instantaneous and characterized by a cluster density of 10{sup 11}-10{sup 12} cm{sup −2}. The amount of deposited Ag follows a t{sup 1/2} dependence in agreement with a Cottrell diffusion limited mechanism. At the same time, during the deposition, the cluster density reduces by a factor 5. This behavior is in contrast with the assumption of immobile clusters. We show in the present work that coalescence and aggregation occur also in the samples immersed in the diluted hydrofluoric acid (HF) solution without the presence of Ag{sup +}. Clusters agglomerate according to a process of dynamic coalescence, typical of colloids, followed by atomic redistribution at the contact regions with the generation of multiple internal twins and stacking-faults. The normalized size distributions in terms of r/r{sub mean} follow also the prediction of the Smoluchowski ripening mechanism. No variation of the cluster density occurs for samples immersed in pure H{sub 2}O solution. The different behavior might be associated to the strong attraction of clusters to oxide-terminated Si surface in presence of water. The silver clusters are instead weakly bound to hydrophobic H-terminated Si in presence of HF. HF causes then the detachment of clusters and a random movement on the silicon surface with mobility of about 10{sup −13} cm{sup 2}/s. Attractive interaction (probably van der Waals) among particles promotes coarsening.

  5. Fluidized bed electrowinning of chromium from very dilute solutions

    SciTech Connect

    Hu, X.; Bautista, R.G.

    1988-10-01

    The Fluidized Bed Electrochemical Reactor (FBER) was used to electrowin chromium from very dilute solutions, ranging in concentration from 0.52 to 3.12 g Cr/1 at pH = 2. The cathode consisted of particulate chromium (450-600 ..mu..m diam.) with a current feeder made of carbon bars and a tubular lead anode in a cylindrical cell. The current efficiency was in the range of 0.08-0.22. The bed expansion, deposition rate, conversion ratio of Cr(VI) to Cr(III) and voltage - current characteristic of the cell were studied. The results indicate that the use of the FBER will make possible the removal of chromium from very dilute solutions without the introduction of other chemicals which would need to be removed or treated further downstream to satisfy environmental abatement codes.

  6. Semi-dilute galactomannan solutions: observations on viscosity scaling behavior of guar gum.

    PubMed

    Pollard, Michael A; Fischer, Peter

    2014-11-19

    Based on experimental work involving evaluation of viscosity enhancement of aqueous solutions by high molecular weight guar gum, we have observed that the shear viscosity scaling exponent b for semi-dilute solutions, ηsp ~ (c[η])(b), is sensitive to molecular weight, being approximately 4.7 for native samples and decreasing progressively as Mw is lowered. The critical overlap parameter demarcating the dilute and semi-dilute regimes also depends on the molecular weight as (c[η])* ~Mw(-0.82). Consequently, viscosity-concentration plots fail to achieve overlap using only specific viscosity and overlap concentration as reducing variables, a commonly accepted empiricism for random-coil polysaccharides. To bridge the gap, we propose to account for water solubility, its temperature dependence and the resulting chain flexibility as additional factors to fully describe the solution behavior of these highly-important raw materials.

  7. Semi-dilute galactomannan solutions: observations on viscosity scaling behavior of guar gum.

    PubMed

    Pollard, Michael A; Fischer, Peter

    2014-11-19

    Based on experimental work involving evaluation of viscosity enhancement of aqueous solutions by high molecular weight guar gum, we have observed that the shear viscosity scaling exponent b for semi-dilute solutions, ηsp ~ (c[η])(b), is sensitive to molecular weight, being approximately 4.7 for native samples and decreasing progressively as Mw is lowered. The critical overlap parameter demarcating the dilute and semi-dilute regimes also depends on the molecular weight as (c[η])* ~Mw(-0.82). Consequently, viscosity-concentration plots fail to achieve overlap using only specific viscosity and overlap concentration as reducing variables, a commonly accepted empiricism for random-coil polysaccharides. To bridge the gap, we propose to account for water solubility, its temperature dependence and the resulting chain flexibility as additional factors to fully describe the solution behavior of these highly-important raw materials. PMID:25347591

  8. High-throughput ab-initio dilute solute diffusion database

    PubMed Central

    Wu, Henry; Mayeshiba, Tam; Morgan, Dane

    2016-01-01

    We demonstrate automated generation of diffusion databases from high-throughput density functional theory (DFT) calculations. A total of more than 230 dilute solute diffusion systems in Mg, Al, Cu, Ni, Pd, and Pt host lattices have been determined using multi-frequency diffusion models. We apply a correction method for solute diffusion in alloys using experimental and simulated values of host self-diffusivity. We find good agreement with experimental solute diffusion data, obtaining a weighted activation barrier RMS error of 0.176 eV when excluding magnetic solutes in non-magnetic alloys. The compiled database is the largest collection of consistently calculated ab-initio solute diffusion data in the world. PMID:27434308

  9. Modeling Corrosion Reactions of Steel in a Dilute Carbonate Solution

    NASA Astrophysics Data System (ADS)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2016-02-01

    This research models the corrosion reactions of a high-strength steel in an aerated, dilute, carbonate solution during a single-cycle voltammetry. Based on a previous study (Eliyan et al. in J Mater Eng Perform 24(6):1-8, 2015) and a literature survey, the corrosion reactions of the cathodic reduction, anodic dissolution, and passivation, as well as the interfacial interactions and the chemistry of the corrosion products are illustrated in schematics. The paper provides a visual guide on the corrosion reactions for steel in carbonate solutions based on the available mechanistic details that were reported and are still being investigated in literature.

  10. A lattice Boltzmann method for dilute polymer solutions.

    PubMed

    Singh, Shiwani; Subramanian, Ganesh; Ansumali, Santosh

    2011-06-13

    We present a lattice Boltzmann approach for the simulation of non-Newtonian fluids. The method is illustrated for the specific case of dilute polymer solutions. With the appropriate local equilibrium distribution, phase-space dynamics on a lattice, driven by a Bhatnagar-Gross-Krook (BGK) relaxation term, leads to a solution of the Fokker-Planck equation governing the probability density of polymer configurations. Results for the bulk rheological characteristics for steady and start-up shear flow are presented, and compare favourably with those obtained using Brownian dynamics simulations. The new method is less expensive than stochastic simulation techniques, particularly in the range of small to moderate Weissenberg numbers (Wi).

  11. Disappearance of high frequency modes in polymer dilute solution viscoelasticity

    NASA Astrophysics Data System (ADS)

    Larson, Ronald; Jain, Semant

    2009-03-01

    We address the problem of the ``missing modes'' in the high frequency rheology of dilute polymer solutions. According to the Rouse-Zimm theory, the slow viscoelastic response of dilute polymers is dominated by the collective motion of the chain, as described by a bead-spring model. However, one expects this description to break down at high frequencies at which chain motion on scales too small to be represented by beads and springs should be evident; this motion should be controlled by rotations of individual backbone bonds of the polymer. The viscoelastic response produced by these ``local modes'' is observable in polymer melts; however, for dilute polymer solutions, the ``local modes'' are absent from viscoelastic spectra, as shown by Schrag and coworkers (Peterson, et al., J. Polym. Sci. B, 39:2860 (2001)). Here we address this problem by directly simulating single polymer chains using Brownian dynamics simulations, with realistic bending and torsional potentials. We show using these simulations that the ``missing modes'' result from barriers to bond rotation that make the chain ``dynamically rigid'' at high frequencies. As a result, the ``dynamical Kuhn length'' of the chain exceeds the static one, and the chain at high frequencies is not able to explore local conformations as fast as would be needed for their relaxation to contribute to the mechanical relaxation spectrum.

  12. Stability of dilute solutions of uranium, lead, and thorium ions

    USGS Publications Warehouse

    Milkey, R.G.

    1954-01-01

    Standard solutions and samples containing a few micrograms of metallic ions per milliliter are frequently used in determination of trace elements. It is important to know whether the concentrations of such solutions remain constant from day to day. The stability of dilute solutions of three metallic ions-uranium, lead, and thorium-has been investigated. Solutions containing concentrations of metallic ions, ranging from 1000 to 0.1 ?? per milliliter, were allowed to stand for approximately 2.5 months, and then the metallic ion content of those solutions that had lost strength was determined. Both adsorption and hydrolysis variously influenced the solute loss, but the minimum pH at which loss of concentration of lead and uranium occurred seemed to coincide with the pH at which the hydrolyzed metal ions began to precipitate. No increase in the stability of the solutions was obtained by substituting polyethylene containers for borosilicate glass. The solutions that lost strength could not be restored promptly to the original concentration by manual means, such as shaking them vigorously for several minutes.

  13. Molecular dynamics of a dilute solution of hydrogen in palladium

    NASA Astrophysics Data System (ADS)

    Pratt, Lawrence R.; Eckert, J.

    1989-06-01

    Molecular-dynamics results on a dilute solution of H in Pd are presented and compared with available incoherent inelastic neutron-scattering results. The embedded-atom model adopted here does a good job of describing the H-Pd atomic forces probed by incoherent inelastic neutron scattering. The time correlation functions associated with the computed spectra are strongly damped and indicative of the anharmonicity that has been suggested as the principal contribution to the anomalous isotope dependence of the superconducting transition temperature in PdH. These results highlight the fact that the H-atom vibrations in Pd-H solutions are low-frequency, large-amplitude vibrations relative to vibrations of H atoms in usual covalent interactions. The rms displacement of the H atom from its mean position in the center of the Pd octahedron compares favorably with the available neutron-diffraction results.

  14. Pretreatment of rice straw using a butanone or an acetaldehyde dilute solution explosion for producing ethanol.

    PubMed

    Zhang, Jian; Zhang, Wen-Xue; Yang, Jian; Liu, Yue-Hong; Zhong, Xia; Wu, Zheng-Yun; Kida, Kenji; Deng, Yu

    2012-04-01

    Ethanol conversion from rice straw using butanone and acetaldehyde dilute solution explosions was evaluated based on the optimization of pure water explosion. To decrease residual inhibitor content, the exploded slurry was dried and investigated at different temperature. Using a 0.9-mol/L butanone solution explosion, with the explosion pressure set at 3.1 MPa, the residence time at 7 min, the dried rice straw-to-water ratio at 1:3 (w/w), and the exploded slurry drying temperuture at 90 °C for 8 h, the yields of total sugar, glucose, and xylose were 85%, 88%, 82% (w/w), respectively, and the ethanol productivity was 26.0 g/100 g rice straw dry matter. Moreover, 0.5-mol/L acetaldehyde dilute solution explosion improved the efficiency of enzymatic hydrolysis (EH) and simultaneous saccharification and co-fermentation (SSCF), and the residual inhibitors had negligible effects on EH and SSCF after detoxification by drying. The results suggested that compared with pure water explosions, the use of butanone and of acetaldehyde dilute solution explosions lowered the explosive temperature and improved the sugar yield, although relative crystallinity of the rice straw dry matter was increased after the explosion. PMID:22371064

  15. Dynamics in Perturbed Very Dilute Aqueous Solutions: Theory and Experimental Evidence

    NASA Astrophysics Data System (ADS)

    Yinnon, Tamar A.; Elia, Vittorio

    2013-02-01

    Perturbed very dilute aqueous solutions are investigated by analyzing their electric conductivity (χ). Foci include titrations and quasi-periodic oscillations of χ spanning several months. The χ data reflect persistent dissipative supramolecular self-organization. This paper's successful consistent explanations of the χ measurements corroborate earlier quantum field theoretical predictions. For example: (1) Permanent polarization results from quantum electro-dynamical interactions mediated auto-ordering of water molecules and molecular aggregates which have electric dipole moments. (2) The aggregates are created by exciting very dilute aqueous solutions, generating long lasting (cold) vortices in crystalline-like-structured super-fluidic domains. These domains are only present when the concentration (C) is lower than a solute dependent transitions concentration (Ctrans). Typically, Ctrans is of the order of 10-4 M or below.

  16. Hydrodynamic properties of rodlike and disklike particles in dilute solution

    NASA Astrophysics Data System (ADS)

    Ortega, A.; García de la Torre, J.

    2003-11-01

    The hydrodynamic properties of cylindrical (rodlike and discoidal) particles in dilute solution have been computed using the bead-shell model treatment. Previous results [Tirado and Garcı´a de la Torre, J. Chem. Phys. 71, 2581 (1979); 73, 1993 (1980)] for rods with length-to-diameter ratio p>2 are now extended to short cylinders and disks down to p=0.1. The intrinsic viscosity is obtained for rods and disks, and results are presented for the three rotational relaxation times of a cylindrical particle. The hydrodynamic properties are expressed in forms that have a weak variation with p, and are therefore useful for the analysis of experimental values. We present examples of the determination of the length and diameter of the cylindrical particles, for DNA oligonucleotides and tobacco mosaic virus.

  17. Ionizing radiation induced degradation of monuron in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Kovács, Krisztina; He, Shijun; Míle, Viktória; Földes, Tamás; Pápai, Imre; Takács, Erzsébet; Wojnárovits, László

    2016-07-01

    The decomposition of monuron was investigated in dilute aqueous solutions using pulse radiolysis and γ-radiolysis in order to identify the intermediates and final products. The main reaction takes place between monuron and the hydroxyl radicals yielding hydroxycyclohexadienyl type radicals with a second order rate constant of (7.4±0.2)×109 mol-1 dm3 s-1. In •OH reactions, the aminyl and phenoxyl radicals may also form. Dechlorination was observed in both hydroxyl radical and hydrated electron reactions. The •OH induced dechlorination reactions are suggested to occur through OH substitution or phenoxyl radical formation. The rate of oxidation is very high in the presence of dissolved oxygen. Some of the results are also supported by quantum chemical calculations.

  18. Dry dilute acid pretreatment by co-currently feeding of corn stover feedstock and dilute acid solution without impregnation.

    PubMed

    He, Yanqing; Zhang, Jian; Bao, Jie

    2014-04-01

    Impregnation of lignocellulose materials with dilute acid solution is a routine operation in conventional dilute acid pretreatment. The dry dilute acid pretreatment (DDAP) at high solids content up to 70% is naturally considered to require longer impregnation time. In this study, a co-currently feeding operation of corn stover and dilute sulfuric acid solution without any impregnation was tested for DDAP. The DDAP pretreated corn stover without impregnation is found to be essentially no difference in pretreatment efficiency compared to those with impregnation in the helically agitated reactor. The yield from cellulose to ethanol in SSF again shows no obvious difference between the DDAP pretreated corn stover with and without impregnation. This study suggests that impregnation in DDAP was not necessary under the helical agitation mixing. The results provided a useful way of cost reduction and process simplification in pretreatment. PMID:24630497

  19. Dry dilute acid pretreatment by co-currently feeding of corn stover feedstock and dilute acid solution without impregnation.

    PubMed

    He, Yanqing; Zhang, Jian; Bao, Jie

    2014-04-01

    Impregnation of lignocellulose materials with dilute acid solution is a routine operation in conventional dilute acid pretreatment. The dry dilute acid pretreatment (DDAP) at high solids content up to 70% is naturally considered to require longer impregnation time. In this study, a co-currently feeding operation of corn stover and dilute sulfuric acid solution without any impregnation was tested for DDAP. The DDAP pretreated corn stover without impregnation is found to be essentially no difference in pretreatment efficiency compared to those with impregnation in the helically agitated reactor. The yield from cellulose to ethanol in SSF again shows no obvious difference between the DDAP pretreated corn stover with and without impregnation. This study suggests that impregnation in DDAP was not necessary under the helical agitation mixing. The results provided a useful way of cost reduction and process simplification in pretreatment.

  20. Droplet Size Distributions in Atomization of Dilute Viscoelastic Solutions

    NASA Astrophysics Data System (ADS)

    Keshavarz, Bavand; McKinley, Gareth; Houze, Eric; Moore, John; Pottiger, Michael; Cotts, Patricia; M. I. T. Collaboration; DuPont Collaboration

    2012-11-01

    The droplet size probability distribution functions (PDF) for atomization/fragmentation processes in Newtonian fluids are now generally accepted to be close to Gamma distributions. Despite the great practical importance, little is known about the nature of corresponding distributions for viscoelastic liquids, e.g. polymeric solutions such as pesticide sprays and paints. We present data from air-assisted atomization experiments for model viscoelastic solutions composed of very dilute solutions of polyethylene oxide. Although the addition of small amounts of high molecular weight polymer keeps the fluid shear viscosity and surface tension close to the solvent values, the size distributions are skewed towards higher values of the Sauter mean diameter. We show that the PDF curves for these weakly-elastic fluids are well described by Gamma distributions, but the exponent n is systematically decreased by fluid elasticity. Flow visualization images show that this behavior arises from the non-linear dynamics close to the break-up point which are dominated by an elasto-capillary force balance within the thinning ligaments and the magnitude of the extensional viscosity in the viscoelastic fluid. Mechanical Engineering Department, Cambridge, MA.

  1. Enhancing wastewater reuse by forward osmosis with self-diluted commercial fertilizers as draw solutes.

    PubMed

    Zou, Shiqiang; He, Zhen

    2016-08-01

    Using fertilizers as draw solutes in forward osmosis (FO) can accomplish wastewater reuse with elimination of recycling draw solute. In this study, three commercial fast-release all-purpose solid fertilizers (F1, F2 and F3) were examined as draw solutes in a submerged FO system for water extraction from either deionized (DI) water or the treated wastewater. Systematic optimizations were conducted to enhance water extraction performance, including operation modes, initial draw concentrations and in-situ chemical fouling control. In the mode of the active layer facing the feed (AL-F or FO), a maximum of 324 mL water was harvested using 1-M F1, which provided 41% of the water need for fertilizer dilution for irrigation. Among the three fertilizers, F1 containing a lower urea content was the most favored because of a higher water extraction and a lower reverse solute flux (RSF) of major nutrients. Using the treated wastewater as a feed solution resulted in a comparable water extraction performance (317 mL) to that of DI water in 72 h and a maximum water flux of 4.2 LMH. Phosphorus accumulation on the feed side was mainly due to the FO membrane solute rejection while total nitrogen and potassium accumulation was mainly due to RSF from the draw solute. Reducing recirculation intensity from 100 to 10 mL min(-1) did not obviously decrease water flux but significantly reduced the energy consumption from 1.86 to 0.02 kWh m(-3). These results have demonstrated the feasibility of using commercial solid fertilizers as draw solutes for extracting reusable water from wastewater, and challenges such as reverse solute flux will need to be further addressed. PMID:27174605

  2. Enthalpy of dilution of maltodextrin in water

    NASA Astrophysics Data System (ADS)

    Wohlfarth, Ch.

    This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

  3. Nonequilibrium thermodynamics of dilute polymer solutions in flow

    SciTech Connect

    Latinwo, Folarin; Hsiao, Kai-Wen; Schroeder, Charles M.

    2014-11-07

    Modern materials processing applications and technologies often occur far from equilibrium. To this end, the processing of complex materials such as polymer melts and nanocomposites generally occurs under strong deformations and flows, conditions under which equilibrium thermodynamics does not apply. As a result, the ability to determine the nonequilibrium thermodynamic properties of polymeric materials from measurable quantities such as heat and work is a major challenge in the field. Here, we use work relations to show that nonequilibrium thermodynamic quantities such as free energy and entropy can be determined for dilute polymer solutions in flow. In this way, we determine the thermodynamic properties of DNA molecules in strong flows using a combination of simulations, kinetic theory, and single molecule experiments. We show that it is possible to calculate polymer relaxation timescales purely from polymer stretching dynamics in flow. We further observe a thermodynamic equivalence between nonequilibrium and equilibrium steady-states for polymeric systems. In this way, our results provide an improved understanding of the energetics of flowing polymer solutions.

  4. Alyssum homolocarpum seed gum: Dilute solution and some physicochemical properties.

    PubMed

    Hesarinejad, M A; Razavi, Seyed M A; Koocheki, A

    2015-11-01

    The objective of this study was to investigate the effect of various temperatures (25-65°C) on some dilute solution properties of Alyssum homolocarpum seed gum (AHSG) as a novel potential source of hydrocolloid. Monosaccharide composition, FTIR analysis and molecular parameters were determined to provide more structural information. The results indicated that AHSG had a low molecular weight (3.66×10(5)Da), medium intrinsic viscosity (18.34dl/g) at 25°C, relatively flexible chain with a chain flexibility parameter of 618.54, and activation energy of 0.51×10(7)J/kgmol. With rise in temperature from 25 to 55°C, the intrinsic viscosity decreased as well as coil radius and volume of AHSG. The shape factor of AHSG macromolecule was spherical at all temperatures. The electrostatic interaction and particle size of AHSG solution were -25.81mV (at neutral pH) and 225.36nm, respectively. The results revealed that AHSG had high total sugar content (85.33%), small amount of uronic acids (5.63%) and it is likely a galactan-type polysaccharide. The FTIR spectra showed that AHSG behaved like a typical polyelectrolyte because of the presence of carboxyl and hydroxyl groups.

  5. Chitosan sorbents for platinum sorption from dilute solutions

    SciTech Connect

    Guibal, E.; Larkin, A.; Vincent, T.; Tobin, J.M.

    1999-10-01

    Chitosan has proved efficient at removing platinum in dilute effluents. The maximum uptake capacity reaches 300 mg/g (almost 1.5 mmol/g). The optimum pH for sorption is pH 2. A glutaraldehyde cross-linking pretreatment is necessary to stabilize the biopolymer in acidic solutions. Sorption isotherms have been studied as a function of pH, sorbent particle size, and the cross-linking ratio. Surprisingly, the extent of the cross-linking (determined by the concentration of the cross-linking agent in the treatment bath) has no significant influence on uptake capacity. Competitor anions such as chloride or nitrate induce a large decrease in the sorption efficiency. Sorption kinetics show also that uptake rate is not significantly changed by increasing either the cross-linking ratio or the particle size of the sorbent. Mass transfer rates are significantly affected by the initial platinum concentration and by the conditioning of the biopolymer. Gel-bead conditioning appears to reduce the sorption rate. While for molybdate and vanadate ions, mass transfer was governed by intraparticle mass transfer, for platinum, both external and intraparticle diffusion control the uptake rate. In contrast with the former ions, platinum does not form polynuclear hydrolyzed species, which are responsible for steric hindrance of diffusion into the polymer network.

  6. Conformation of ionizable poly Para phenylene ethynylene in dilute solutions

    DOE PAGESBeta

    Wijesinghe, Sidath; Maskey, Sabina; Perahia, Dvora; Grest, Gary S.

    2015-11-03

    The conformation of dinonyl poly para phenylene ethynylenes (PPEs) with carboxylate side chains, equilibrated in solvents of different quality is studied using molecular dynamics simulations. PPEs are of interest because of their tunable electro-optical properties, chemical diversity, and functionality which are essential in wide range of applications. The polymer conformation determines the conjugation length and their assembly mode and affects electro-optical properties which are critical in their current and potential uses. The current study investigates the effect of carboxylate fraction on PPEs side chains on the conformation of chains in the dilute limit, in solvents of different quality. The dinonylmore » PPE chains are modeled atomistically, where the solvents are modeled both implicitly and explicitly. Dinonyl PPEs maintained a stretched out conformation up to a carboxylate fraction f of 0.7 in all solvents studied. The nonyl side chains are extended and oriented away from the PPE backbone in toluene and in implicit good solvent whereas in water and implicit poor solvent, the nonyl side chains are collapsed towards the PPE backbone. Thus, rotation around the aromatic ring is fast and no long range correlations are seen within the backbone.« less

  7. Detection of dilute organic acids in water by inelastic tunneling spectroscopy

    NASA Technical Reports Server (NTRS)

    Skarlatos, Y.; Barker, R. C.; Haller, G. L.; Yelon, A.

    1974-01-01

    Study of inelastic electron tunneling spectroscopy (IETS) spectra obtained from junctions exposed to dilute solutions of organic molecules in both liquid and vapor phases. The results indicate that it is possible in principle to detect the presence and to measure the concentration of at least some organic molecules in dilute aqueous solution by means of the IETS technique. Some fine points pertaining to the application of this technique are discussed, and it is pointed out that through appropriate refinements IETS may become a valuable tool for analytical water chemistry.

  8. Nanostructures of colloidal complexes formed in oppositely charged polyelectrolyte/surfactant dilute aqueous solutions

    NASA Astrophysics Data System (ADS)

    Trabelsi, S.; Guillot, S.; Ritacco, H.; Boué, F.; Langevin, D.

    2007-07-01

    Small-angle neutron scattering measurements were performed on dilute solutions of carboxymethylcellulose/DTAB complexes in water in order to determine their size, shape and internal structures. At low polymer content, the complexes are spherical, rather monodisperse and probably made of polymer chains intercalated between surfactant micelles. Moreover, we show that these micelles have a similar cubic arrangement than found in polymer/surfactant precipitates formed at higher surfactant concentrations. At larger polymer content, in the semi-dilute polyelectrolyte regime, the complexes are larger, softer and polydisperse. However, they possess a similar internal structure in both regimes. Carboxymethylcellulose/CTAB complexes are also large, soft and polydisperse but do not seem to exhibit well-defined internal structures.

  9. The dissolution of quartz in dilute aqueous solutions of organic acids at 25 degree C

    SciTech Connect

    Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P. )

    1988-06-01

    The dissolution of quartz in dilute aqueous solutions of organic acids at 25{degree}C and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 {mu}mole/Kg compared to 50 {mu}mole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH. The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

  10. The dissolution of quartz in dilute aqueous solutions of organic acids at 25°C

    NASA Astrophysics Data System (ADS)

    Bennett, P. C.; Melcer, M. E.; Siegel, D. I.; Hassett, J. P.

    1988-06-01

    The dissolution of quartz in dilute aqueous solutions of organic acids at 25° and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 μmole/Kg compared to 50 μmole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH. The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid anions which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

  11. Separation processes using expulsion from dilute supercritical solutions

    DOEpatents

    Cochran, Jr., Henry D.

    1993-01-01

    A process for separating isotopes as well as other mixtures by utilizing the behavior of dilute repulsive or weakly attractive elements of the mixtures as the critical point of the solvent is approached.

  12. Separation processes using expulsion from dilute supercritical solutions

    DOEpatents

    Cochran, H.D. Jr.

    1993-04-20

    A process is described for separating isotopes as well as other mixtures by utilizing the behavior of dilute repulsive or weakly attractive elements of the mixtures as the critical point of the solvent is approached.

  13. Opalescence in monoclonal antibody solutions and its correlation with intermolecular interactions in dilute and concentrated solutions.

    PubMed

    Raut, Ashlesha S; Kalonia, Devendra S

    2015-04-01

    Opalescence indicates physical instability of a formulation because of the presence of aggregates or liquid-liquid phase separation in solution and has been reported for monoclonal antibody (mAb) formulations. Increased solution opalescence can be attributed to attractive protein-protein interactions (PPIs). Techniques including light scattering, AUC, or membrane osmometry are routinely employed to measure PPIs in dilute solutions, whereas opalescence is seen at relatively higher concentrations, where both long- and short-range forces contribute to overall PPIs. The mAb molecule studied here shows a unique property of high opalescence because of liquid-liquid phase separation. In this study, opalescence measurements are correlated to PPIs measured in diluted and concentrated solutions using light scattering (kD ) and high-frequency rheology (G'), respectively. Charges on the molecules were calculated using zeta potential measurements. Results indicate that high opalescence and phase separation are a result of the attractive interactions in solution; however, the presence of attractive interactions do not always imply phase separation. Temperature dependence of opalescence suggests that thermodynamic contribution to opalescence is significant and Tcloud can be utilized as a potential tool to assess attractive interactions in solution.

  14. Evaluation of heavy water for indicator dilution cardiac output measurement

    SciTech Connect

    Schreiner, M.S.; Leksell, L.G.; Neufeld, G.R. )

    1989-10-01

    We evaluated deuterium oxide (D2O) as a tracer for cardiac output measurements. Cardiac output measurements made by thermodilution were compared with those made by indicator dilution with D2O and indocyanine green as tracers. Five triplicate measurements for each method were made at intervals of 30 minutes in each of 9 anesthetized, mechanically ventilated goats. Cardiac output ranged between 0.68 and 3.79 L/min. The 45 data points yielded a correlation coefficient of 0.948 for the comparison of D2O indicator dilution cardiac output measurements with thermodilution measurements and a linear regression slope of 1.046. D2O indicator dilution measurements were biased by -0.11 +/- 0.22 L/min compared with thermodilution measurements and had a standard deviation of +/- 0.12 L/min for triplicate measurements. Hematocrits ranging between 20 and 50 vol% had no effect on optical density for D2O. D2O is more stable than indocyanine green and approximately one-tenth the price (40 cents per injection compared with $4). The basic instrumentation cost of approximately $9,000 is an additional initial expense, but provides the ability to perform pulmonary extravascular water measurements with a double-indicator dilution technique. D2O has potential as a tracer for the clinical determination of indicator dilution cardiac output measurements and pulmonary extravascular water measurements.

  15. The electrochemistry of SIMFUEL in dilute alkaline hydrogen peroxide solutions

    NASA Astrophysics Data System (ADS)

    Goldik, Jon

    The work described in this thesis is a study of the electrochemistry of SIMFUEL (SIMulated nuclear FUEL) in dilute, alkaline hydrogen peroxide solutions. In the first set of experiments, the reaction of H2O 2 on SIMFUEL electrodes was studied electrochemically and under open circuit conditions in 0.1 mol L-1 NaCl solutions at pH 9.8. The composition of the oxidized UO2 surface was determined by X-ray photoelectron spectroscopy. Hydrogen peroxide reduction was found to be catalyzed by the formation of a mixed UIV/UV (UO 2+x) surface layer, but to be blocked by the accumulation of UVI species (UO3· yH2O or adsorbed (UO2)2+) on the electrode surface. The formation of this UVI layer blocks both H2O2 reduction and oxidation, thereby inhibiting the potentially rapid H2O2 decomposition reaction to H2O and O2. Decomposition is found to proceed at a rate controlled by the desorption of the adsorbed (UO2)2+ or reduction of adsorbed O2 species. Reduction of (O2) ads is coupled to the slow oxidative dissolution of UO2 and formation of a corrosion product deposit of UO3· yH2O. In the second series of experiments, the electrochemical reduction of hydrogen peroxide on SIMFUEL was studied using the steady-state polarization technique. Kinetic parameters for the reaction, such as Tafel slopes and reaction orders, were determined. The results were interpreted in terms of a chemical-electrochemical mechanism involving UIV/UV donor-acceptor reduction sites. The large values of the Tafel slopes and the fractional reaction orders with respect to H2O2 can be understood in terms of the potential-dependent surface coverage of active sites, similar to that observed in the reduction of hydrogen peroxide on oxidized copper surfaces. The effects of pH over the range 10-13 were also investigated. The H2O 2 reduction currents were nearly independent of pH in the range 10-11, but were slowed at more alkaline values. The change in pH dependence appears to be related to the acid-base properties

  16. Form and stability of aluminum hydroxide complexes in dilute solution

    USGS Publications Warehouse

    Hem, John David; Roberson, Charles Elmer

    1967-01-01

    Laboratory studies of solutions 4.53 x 10 -4 to 4.5 x 10 -5 molal (12.2-1.2 ppm) in aluminum, in 0.01 molal sodium perchlorate, were conducted to obtain information as to the probable behavior of aluminum in natural water. When the solutions were brought to pH 7.5-9.5 and allowed to stand for 24 hours, a precipitate was obtained which was virtually amorphous as shown by X-rays, and which had a solubility equivalent to that of boehmite. This precipitate had a hydrolysis constant (*Ks4) of 1.93 x 10 -13a. When solutions were allowed to stead at this pH range for 10 days, their precipitates gave the X-ray pattern of bayerite (*Ks4 = 1.11 > (10- 4). These hydrolysis constants were obtained at 25?C. and corrected to zero ionic strength and are in close agreement with other published values. The predominant dissolved form in this pH range is Al(OH) -4. Below neutral pH (7.0) the dissolved aluminum species consist of octahedral units in which each aluminum ion is surrounded by six water molecules or hydroxide ions. Single units such as Al(OH2)6 + 3 and AlOH(OH2)5+2 are most abundant below pH 5.0, and where the molar ratio (r) of combined hydroxide to total dissolved aluminum is low. When r is greater than 1.0, polymerization of the octahedral units occurs. When r is between 2.0 and 3.0, solutions aged for 10 days or more contained colloidal particles between 0.10 and 0.45 ? in diameter. Particles whose diameters were greater than 0.10 ? were identified by X-ray diffraction as gibbsite. Particles smaller than 0.10 ? were also present and were shown by means of the electron microscope to have a hexagonal crystal pattern. Structured material consisting of sheets of coalesced six-membered rings of aluminum ions held together by double OH bridges has a distinctive kinetic behavior. This property was used to determine amounts of polymerized material in solutions having r between 1.0 and 3.0 after aging times ranging from a few hours to more than 4 months. Aging increased the

  17. Dynamic dissolution of halite rock during flow of diluted saline solutions

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Alon-Mordish, C.; Yechieli, Y.

    2010-12-01

    Continuous recession of the Dead Sea (DS) water level influences the location of the underground interface between fresh aquifer water and DS water (DSW). As the interface moves, salt layers are exposed to and potentially dissolved by dilute solutions. This process has resulted in the formation of hundreds of sinkholes along the DS shore during the last decade. Very little is known about the dynamics of salt dissolution during flow of dilute saline solution. Patterns and kinetics of halite dissolution were examined during the flow of unsaturated DSW solutions in a series of laboratory experiments. Flow experiments were carried out in natural halite cores taken from boreholes drilled along the DS shore (15-30 m deep). First, the permeability of the core was determined using 100% DSW. Next, 100% DSW was replaced by diluted DSW and changes in permeability and flow were studied. Dissolution patterns were monitored by digital camera and computerized tomography (CT). The mass of NaCl dissolved from the core was determined based on outlet solution density. In one set of experiments, a 2-mm wide channel was drilled through the length of the entire core prior to flow to study dissolution along a preexisting channel. Our results show that above a critical flow velocity (0.01ml/min), dissolution developed along preferential pathways and formed distinct channels. The channel structure related to the halite properties and internal heterogeneities. Under flow velocity less than 0.01 ml/min, dissolution developed as a propagating front. At these low velocities, salt reprecipitation in pores often resulted in clogging and cessation of flow through the salt core. The effect of solution density on the dissolution pattern was also found to be important, as more channels developed upward due to gravitational fractionation. In summary, our results suggest that dissolution through massive salt layers will occur in very specific locations where resistance to flow is at a minimum. These

  18. Hydration of Kr(aq) in dilute and concentrated solutions

    SciTech Connect

    Chaudhari, Mangesh I.; Sabo, Dubravko; Pratt, Lawrence R.; Rempe, Susan B.

    2014-10-13

    Molecular dynamics simulations of water with both multi-Kr and single Kr atomic solutes are carried out to implement quasi-chemical theory evaluation of the hydration free energy of Kr(aq). This approach obtains free energy differences reflecting Kr–Kr interactions at higher concentrations. Those differences are negative changes in hydration free energies with increasing concentrations at constant pressure. The changes are due to a slight reduction of packing contributions in the higher concentration case. The observed Kr–Kr distributions, analyzed with the extrapolation procedure of Krüger et al., yield a modestly attractive osmotic second virial coefficient, B2 ≈ -60 cm3/mol. Moreover, the thermodynamic analysis interconnecting these two approaches shows that they are closely consistent with each other, providing support for both approaches.

  19. Hydration of Kr(aq) in dilute and concentrated solutions

    DOE PAGESBeta

    Chaudhari, Mangesh I.; Sabo, Dubravko; Pratt, Lawrence R.; Rempe, Susan B.

    2014-10-13

    Molecular dynamics simulations of water with both multi-Kr and single Kr atomic solutes are carried out to implement quasi-chemical theory evaluation of the hydration free energy of Kr(aq). This approach obtains free energy differences reflecting Kr–Kr interactions at higher concentrations. Those differences are negative changes in hydration free energies with increasing concentrations at constant pressure. The changes are due to a slight reduction of packing contributions in the higher concentration case. The observed Kr–Kr distributions, analyzed with the extrapolation procedure of Krüger et al., yield a modestly attractive osmotic second virial coefficient, B2 ≈ -60 cm3/mol. Moreover, the thermodynamic analysismore » interconnecting these two approaches shows that they are closely consistent with each other, providing support for both approaches.« less

  20. Hydration of Kr(aq) in Dilute and Concentrated Solutions.

    PubMed

    Chaudhari, Mangesh I; Sabo, Dubravko; Pratt, Lawrence R; Rempe, Susan B

    2015-07-23

    Molecular dynamics simulations of water with both multi-Kr and single Kr atomic solutes are carried out to implement quasi-chemical theory evaluation of the hydration free energy of Kr(aq). This approach obtains free energy differences reflecting Kr-Kr interactions at higher concentrations. Those differences are negative changes in hydration free energies with increasing concentrations at constant pressure. The changes are due to a slight reduction of packing contributions in the higher concentration case. The observed Kr-Kr distributions, analyzed with the extrapolation procedure of Krüger et al., yield a modestly attractive osmotic second virial coefficient, B2 ≈ -60 cm(3)/mol. The thermodynamic analysis interconnecting these two approaches shows that they are closely consistent with each other, providing support for both approaches.

  1. Sonochemical degradation of organophosphorus pesticide in dilute aqueous solutions.

    PubMed

    Farooq, Robina; Lin, Feng-Kai; Shaukat, S F; Huang, Jian-Jun

    2003-09-01

    Ultrasonic irradiation was found to accelerate the rate of hydrolysis of omethoate in aqueous solution over the pH range of 2-12. Process parameters studied include pH, steady-state temperature, concentration, and the type of gases. Greater than 96% hydrolysis was observed in 30 minutes through this process and the rate of destruction increased with the help of more soluble and low thermal inert gas. So with Krypton, omethoate was found to undergo rapid destruction as compared with Argon. In the presence of ultrasound, the observed first-order rate of hydrolysis of omethoate is found to be independent of pH. The formation of transient supercritical water (SCW) appears to be an important factor in the acceleration of chemical reactions in the presence of ultrasound. A detailed chemical reaction mechanism for omethoate destruction in water was formulated. Experimental results and theoretical kinetic mechanism demonstrated that the most of the omethoate undergo destruction inside the cavitating holes. A very less effect of temperature on the degradation of omethoate within a temperature range of 20-70 degrees C proves that a small quantity of omethoate undergoes secondary destruction in the bulk liquid.

  2. A comparison of different dilute solution explosions pretreatment for conversion of distillers' grains into ethanol.

    PubMed

    Zhang, Jian; Zhang, Wen-Xue; Wu, Zheng-Yun; Yang, Jian; Liu, Yue-Hong; Zhong, Xia; Deng, Yu

    2013-01-01

    In order to improve the efficiency of distillers' grains converting to ethanol, 13 dilute solution explosions were evaluated based on the optimization of pure water explosion. To decrease residual inhibitor content, the exploded slurry was dried at 105°C. Using a 1.1 mol/L butanone solution explosion, with the explosion temperature set at 160°C (pressure at 1.9 MPa), the residence time at 10 min, and the dried distillers' grains-to-water ratio at 1:2 (w/w), the yields of total sugar, glucose, and xylose were 86%, 89%, and 84% (w/w), respectively, and the ethanol yield was 25.3 g/100 g distillers' grains dry matter. Moreover, the eight other reagent solution explosions improved the efficiency of enzymatic hydrolysis, and of simultaneous saccharification and co-fermentation, and the residual contents of furfural, 5-hydroxymethylfurfural, and acetic acid decreased to an acceptable concentration range after detoxification by drying. The results suggested that compared with pure water explosions, the use of volatile solutions lowered the explosive temperature and improved the sugar yield. This study offers a reference for the further study of lignocellulosic materials with higher starch and hemicelluloses contents as raw materials for converting biomass to bioethanol. PMID:23215651

  3. Self-recognition among different polyprotic macroions during assembly processes in dilute solution.

    PubMed

    Liu, Tianbo; Langston, Melissa L K; Li, Dong; Pigga, Joseph M; Pichon, Céline; Todea, Ana Maria; Müller, Achim

    2011-03-25

    We report a self-recognition phenomenon based on an assembly process in a homogeneous dilute aqueous solution of two nano-scaled, spherical polyprotic metal oxide-based macroions (neutral species in crystals), also called Keplerates of the type [(linker)₃₀(pentagon)₁₂]≡[{M(H₂O)}₃₀{(Mo)Mo₅}₁₂] where M is Fe(III) or Cr(III). Upon deprotonation of the neutral species, the resulting macroions assemble into hollow "blackberry"-type structures through very slow homogeneous dimer-oligomerization processes. Although the geometrical surface structures of the two macroions are practically identical, mixtures of these form homogeneous superstructures, rather than mixed species. The phase separation is based on the difference in macroionic charge densities present during the slow homogeneous dimer or oligomer formation. The surface water ligands' residence times of Cr(III) and Fe(III) differ markedly and lead to very different interfacial water mobilities between the Keplerates.

  4. An improved method of determining vapor-liquid equilibria for dilute organics in aqueous solution.

    PubMed

    Kieckbusch, T G; King, C J

    1979-05-01

    Chromatographic quantitative analyses of aqueous samples containing dilute concentrations of organic solutes are frequently confounded by sorption phenomena, particularly for vapor samples and aged syringes. A novel apparatus was developed for overcoming this problem; it utilizes continual circulation of gas through a thermostated syringe for sampling, followed by a needleless injection into the chromatograph. Precision and reproducibility well under 0.5% can be obtained in this way. This method was applied to a determination of the solubility of isopentyl acetate in water (2600 ppm) by following the equilibrium vapor response for increasing liquid concentrations. It was also used to determine equilibrium partition coefficients for C1-C5 n-acetates between air and water, over a range of temperatures from 25 to 40 degrees C. PMID:19847988

  5. Solubility and reactivity of peroxyacetyl nitrate (PAN) in dilute aqueous salt solutions and in sulphuric acid

    NASA Astrophysics Data System (ADS)

    Frenzel, A.; Kutsuna, S.; Takeuchi, K.; Ibusuki, T.

    The loss rates of PAN in several dilute aqueous salt solutions (NaBr, Na 2SO 3, KI, NaNO 2, FeCl 3, and FeSO 4) and in sulphuric acid were measured at 279 K with a simple bubbler experiment. They are little different from that in pure water. For 5 M sulphuric acid hydrolysis and solubility were determined in the temperature range of 243-293 K. The hydrolysis rate kh=3.2×10 -4 s -1 at 293 K is close to that in water. The observed temperature dependence of the Henry's Law constant H=10- 6.6±0.6exp((4780±420)/T) M atm -1 leads to enthalpy and entropy of solvation Δ Hsolv=-39.7±3.5 kJ mol -1 and Δ Ssolv=-126±11 J mol -1 K -1, respectively.

  6. Spectrofluorimetric determination of trace aluminum in diluted hemodialysis solutions

    NASA Astrophysics Data System (ADS)

    Gündüz, S. Beniz; Küçükkolbaşý, Semahat; Atakol, Orhan; Kýlýç, Esma

    2005-03-01

    In this study, a spectrofluorimetric method has been developed for the determination of aluminum based on the formation of an aluminum complex with N, N'-disalicylidene-1,3-diamino-2-hydroxypropane (DSAHP). The most suitable pH, solvent medium, complex formation time, Schiff base concentration and temperature were determined. The excitation and emission wavelengths were 270 and 437 nm, respectively, in which the DSAHP-Al complex gave the maximum flurescence intensity at pH 3.0 and 6.0 in 50% dioxan-50% water medium. Under these conditions, calibration curves were obtained in three different linear limits, and was found that aluminum could be detected within the concentration limit of 0-10.0 μM and the lowest detection limit being 0.27 ng ml -1. The stochiometry of the DSAHP-Al complex was also determined spectrofluorimetrically under optimal conditions and the molar ratio of DSAHP-Al was calculated as 2:1. Using the developed method, aluminum was detected in hemodialysis solutions, and the results obtained were similar and comparable with those obtained using the method described in the British Pharmacopoeia within 95% confidence limits. This method can be used successfully for the routine determination of aluminum because it is quick, requires less amount of reactives, is sensitive, reliable and reproducible.

  7. Polymer relaxation and stretching dynamics in semi-dilute DNA solutions: a single molecule study

    NASA Astrophysics Data System (ADS)

    Hsiao, Kai-Wen; Brockman, Christopher; Schroeder, Charles

    2015-03-01

    In this work, we study polymer relaxation and stretching dynamics in semi-dilute DNA solutions using single molecule techniques. Using this approach, we uncover a unique scaling relation for longest polymer relaxation time that falls in the crossover regime described by semi-flexible polymer solutions, which is distinct from truly flexible polymer chains. In addition, we performed a series of step-strain experiments on single polymers in semi-dilute solutions in planar extensional flow using an automated microfluidic trap. In this way, we are able to precisely control the flow strength and the amount of strain applied to single polymer chains, thereby enabling direct observation of the full stretching and relaxation process in semi-dilute solutions during transient start-up and flow cessation. Interestingly, we observe polymer individualism in the conformation of single chains in semi-dilute solutions, which to our knowledge has not yet been observed. In addition, we observe the relaxation data can be explained by a multi-exponential decay process after flow cessation in semi-dilute solutions. Overall, our work reports key advance in non-dilute polymer systems from a molecular perspective via direct observation of dynamics in strong flows. DOW fellowship.

  8. 2010 Water & Aqueous Solutions

    SciTech Connect

    Dor Ben-Amotz

    2010-08-13

    Water covers more than two thirds of the surface of the Earth and about the same fraction of water forms the total mass of a human body. Since the early days of our civilization water has also been in the focus of technological developments, starting from converting it to wine to more modern achievements. The meeting will focus on recent advances in experimental, theoretical, and computational understanding of the behavior of the most important and fascinating liquid in a variety of situations and applications. The emphasis will be less on water properties per se than on water as a medium in which fundamental dynamic and reactive processes take place. In the following sessions, speakers will discuss the latest breakthroughs in unraveling these processes at the molecular level: Water in Solutions; Water in Motion I and II; Water in Biology I and II; Water in the Environment I and II; Water in Confined Geometries and Water in Discussion (keynote lecture and poster winners presentations).

  9. Interactions between fluorinated cationic guar gum and surfactants in the dilute and semi-dilute solutions.

    PubMed

    Wang, Chen; Li, Xiaorui; Li, Peizhi; Niu, Yuhua

    2014-01-01

    The interactions between the fluorinated cationic guar gum (FCGG) and ionic surfactants including cetyl trimethyl ammonium bromide (CTAB) and sodium lauryl sulfate (SDS) were studied by light scattering, fluorescence spectroscopy, UV-spectrophotometer, (19)F NMR and dynamic rheometer, respectively. The FCGG is prepared with cationic guar gum, isophorone diisocyanate and 2,2,3,4,4,4-hexafluoro-1-butanol. The results show that, with the addition of the surfactants, the stretching degree of the FCGG chains is increased in the FCGG/CTAB solutions, while the dramatical shrinking of FCGG chain, the phase separation and the re-stretched macromolecules appear successively because of the electricity neutralization reaction in the FCGG/SDS system. The mixed hydrophobic domains in all solutions will be reinforced and then dismantled. The solution elasticity shows up the maximum value accordingly. The surfactants can be embedded in the micro-domains and then hinder the fluorinated segmental motions. The interactions between FCGG and SDS are much stronger than those between FCGG and CTAB.

  10. Instrumental measurements of different homeopathic dilutions of potassium iodide in water.

    PubMed

    Jerman, I; Berden, M; Skarja, M

    1999-01-01

    Although more than 200 years have elapsed since the beginning of homeopathy and in spite of numerous confirmatory scientific experiments, the so-called memory of water is still a highly disputable and controversial theme in scientific circles. To make a contribution to solving this riddle, our research group tried to examine memory properties of water by the method of differential corona discharge Kirlian electrophotography of water-drop pairs. The method is based on a modified form of Kirlian photography with a subsequent thorough computer picture analysis. The potassium iodide (KI) mother solution (0.1M) was diluted in the standard way (without potentisation) or with potentisation (succussion by hand - by striking the vial 60 times against a large book as used traditionally) to 10(-3)M, 10(-6)M, 10(-10)M, 10(-16)M, 10(-17)M and 10(-24)M KI solutions. In the electrophotography method a drop of KI solution was compared with a drop of control water. To get a dependable system of results we compared homeopathic dilutions with ordinary distilled water, sham-potentised distilled water and non-potentised (standard) solutions. The results were analyzed by the Chi-square Goodness-of-fit test and the Sign test. They showed repeatable and statistically significant effects of concentration of KI dilutions as well as potentisation on the corona discharge process (from p < 0.05 to p < 0.001). This indicates that there is some physical basis of molecular (ionic) information imprinted into water. PMID:10472820

  11. Characterizing storm water dispersion and dilution from small coastal streams

    NASA Astrophysics Data System (ADS)

    Romero, Leonel; Siegel, David A.; McWilliams, James C.; Uchiyama, Yusuke; Jones, Charles

    2016-06-01

    Characterizing the dispersion and dilution of storm water from small coastal creeks is important for understanding the importance of land-derived subsidies to nearby ecosystems and the management of anthropogenic pollutants. In Southern California, creek runoff is episodic, intense, and short-lived while the plumes are buoyant, all of which make the field sampling of freshwater plumes challenging. Numerical modeling offers a viable way to characterize these systems. The dilution and dispersion of freshwater from two creeks that discharge into the Santa Barbara Channel, California is investigated using Regional Ocean Modeling System (ROMS) simulations with a horizontal resolution of 100 m. Tight coupling is found among precipitation, hydrologic discharge, wind forcing, and submesoscale flow structures which all contribute to plume evolution. During flooding, plumes are narrow and attached to the coast, due to downwelling/onshore wind forcing and intense vorticity filaments lying parallel to the shelf. As the storm passes, the winds typically shift to offshore/upwelling favorable conditions and the plume is advected offshore which enhances its dilution. Plumes reach the bottom nearshore while they form thin layers a few meters thick offshore. Dilution field of passive tracers released with the runoff is strongly anisotropic with stronger cross-shelf gradients than along-shelf. Dispersion analysis of statistical moments of the passive tracer distribution results in scale-dependent diffusivities consistent with the particle-pair analysis of Romero et al. Model validation, the roles of submesoscale processes, and wind forcing on plume evolution and application to ecological issues and marine resource management are discussed.

  12. Radiation induced degradation of ketoprofen in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Illés, Erzsébet; Takács, Erzsébet; Dombi, András; Gajda-Schrantz, Krisztina; Gonter, Katalin; Wojnárovits, László

    2012-09-01

    The intermediates and final products of ketoprofen degradation were investigated in 0.4 mmol dm-3 solution by pulse radiolysis and gamma radiolysis. For observation of final products UV-vis spectrophotometry and HPLC separation with diode array detection were used, and for identification MS was used. The reactions of •OH lead to hydroxycyclohexadienyl type radical intermediates, in their further reactions hydroxylated derivatives of ketoprofen form as final products. The hydrated electron is scavenged by the carbonyl oxygen and the electron adduct protonates to ketyl radical •OH is more effective in decomposing ketoprofen than hydrated electron. Chemical oxygen demand and total organic carbon content measurements on irradiated aerated solutions showed that using irradiation technology ketoprofen can be mineralised. The initial toxicity of the solution monitored by the Daphnia magna test steadily decreases with irradiation. Using 5 kGy dose no toxicity of the solution was detected with this test.

  13. A theoretical framework for modeling dilution enhancement of non-reactive solutes in heterogeneous porous media.

    PubMed

    de Barros, F P J; Fiori, A; Boso, F; Bellin, A

    2015-01-01

    Spatial heterogeneity of the hydraulic properties of geological porous formations leads to erratically shaped solute clouds, thus increasing the edge area of the solute body and augmenting the dilution rate. In this study, we provide a theoretical framework to quantify dilution of a non-reactive solute within a steady state flow as affected by the spatial variability of the hydraulic conductivity. Embracing the Lagrangian concentration framework, we obtain explicit semi-analytical expressions for the dilution index as a function of the structural parameters of the random hydraulic conductivity field, under the assumptions of uniform-in-the-average flow, small injection source and weak-to-mild heterogeneity. Results show how the dilution enhancement of the solute cloud is strongly dependent on both the statistical anisotropy ratio and the heterogeneity level of the porous medium. The explicit semi-analytical solution also captures the temporal evolution of the dilution rate; for the early- and late-time limits, the proposed solution recovers previous results from the literature, while at intermediate times it reflects the increasing interplay between large-scale advection and local-scale dispersion. The performance of the theoretical framework is verified with high resolution numerical results and successfully tested against the Cape Cod field data.

  14. Phototransformation of selected organophosphorus pesticides in dilute aqueous solutions.

    PubMed

    Zamy, Cécile; Mazellier, Patrick; Legube, Bernard

    2004-05-01

    The photochemical transformation of four selected organophosphorus pesticides (OPs) has been studied in water. Because of their extensive use, disulfoton, isofenfos, isazofos and profenofos were chosen for this study. A solid phase extraction method has been developed to allow low-concentration experiments. Photolysis experiments have been performed both in purified water and in Capot river water (natural water from Martinique) using either monochromatic light at 253.7 nm (purified water) or polychromatic light greater than 285 nm (purified and Capot river waters). Kinetic investigations coupled with analytical studies (identification of degradation products) were performed for the four pesticides. Upon monochromatic irradiation, quantum yields of OP photolysis have been evaluated and in polychromatic irradiation experiments, apparent first-order kinetic constants have been determined. The reactivity is similar in purified and natural water, but differences are observed for each pesticide according to the role that natural organic matter (NOM) plays: filter effect of the light or photosensitizer. For each organophosphorus pesticide, experiments have been performed to identify the photodegradation products. Some photoproduct structures will be proposed according to mass spectral informations. PMID:15142791

  15. Microfluidics Meets Dilute Solution Viscometry: An Undergraduate Laboratory to Determine Polymer Molecular Weight Using a Microviscometer

    ERIC Educational Resources Information Center

    Pety, Stephen J.; Lu, Hang; Thio, Yonathan S.

    2011-01-01

    This paper describes a student laboratory experiment to determine the molecular weight of a polymer sample by measuring the viscosity of dilute polymer solutions in a PDMS microfluidic viscometer. Sample data are given for aqueous solutions of poly(ethylene oxide) (PEO). A demonstration of shear thinning behavior using the microviscometer is…

  16. Single polymer dynamics of linear and architecturally complex chains in semi-dilute solutions

    NASA Astrophysics Data System (ADS)

    Hsiao, Kaiwen; Li, Yanfei; McKenna, Gregory; Schroeder, Charles

    The interplay between polymer topology and concentration gives rise to complex dynamics due to inter- and intramolecular interactions. We use a molecular level approach to study the threading behavior for linear and ring polymers near equilibrium and in non-linear flows. A semi-dilute solution of linear DNA chains is doped with fluorescently labeled ring polymers (circular DNA plasmids), and this material is used to study the dynamics of rings in semi-dilute solutions of linear chains. Single molecule fluorescence microscopy in combination with a custom-built microfluidic trapping system is used to study collective polymer dynamics at the molecular level, which allows us to precisely control flow rates and accumulated fluid strain applied to single polymer. We performed step-strain experiments on ring polymer in linear semi-dilute polymer solutions undergoing deformation in planar extensional flow. In comparison to our previous work on semi-dilute linear chains, ring polymers exhibit large fluctuations in fractional extension at steady state extension, indicating strong interactions with the background polymer solution. Transient stretching dynamics of ring polymer is inhibited in semi-dilute linear background, similar to our previous observation in linear systems. Our findings show that topology and concentration play a strong role on polymer chain dynamics in non-equilibrium flow.

  17. Solubility of drugs in aqueous solutions. Part 4. Drug solubility by the dilute approximation.

    PubMed

    Ruckenstein, E; Shulgin, I

    2004-07-01

    As in our previous publications in this journal [Int. J. Pharm. 258 (2003a) 193; Int. J. Pharm. 260 (2003b) 283; Int. J. Pharm. 267 (2003c) 121], this paper is concerned with the solubility of poorly soluble drugs in aqueous mixed solvents. In the previous publications, the solubilities of drugs were assumed to be low enough for the so-called infinite dilution approximation to be applicable. In contrast, in the present paper, the solubilities are considered to be finite and the dilute solution approximation is employed. As before, the fluctuation theory of solutions is used to express the derivatives of the activity coefficient of a solute in a ternary solution (dilute solute concentrations in a binary solvent) with respect to the concentrations of the solvent and cosolvent. The expressions obtained are combined with a theoretical equation for the activity coefficient of the solute. As a result, the activity coefficient of the solute was expressed through the activity coefficients of the solute at infinite dilution, solute mole fraction, some properties of the binary solvent (composition, molar volume and activity coefficients of the components) and parameters reflecting the nonidealities of binary species. The expression thus obtained was used to derive an equation for the solubility of poorly soluble drugs in aqueous binary solvents which was applied in two different ways. First, the nonideality parameters were considered as adjustable parameters, determined from experimental solubility data. Second, the obtained equation was used to correct the solubilities of drugs calculated via the infinite dilution approximation. It was shown that both procedures provide accurate correlations for the drug solubility.

  18. Preliminary investigation of elongational flow of dilute polymer solutions

    NASA Technical Reports Server (NTRS)

    Peng, S. T. J.; Landel, R. F.

    1976-01-01

    A tubeless siphon apparatus has been set up to measure extensional flow. In this apparatus, the liquid is continuously drawn into a capillary and, after steady flow has been established, the tube is raised above the liquid surface. With viscoelastic liquids, the flow continues and a column can be lifted from the reservoir. At the capillary entrance, an oscillating bead of excess liquid collects which interferes with both the flow and the measurements. This can be minimized by careful control of the liquid-column height. For homogeneous solutions, the column is symmetrical and tapers steadily from the liquid surface to the capillary entrance, with no bulging. Preliminary results show tensile viscosities 1000 times that of the Trouton coefficient and having a very strong dependence on deformation rate. A concentration-stretch rate-reduced variable scheme is proposed.

  19. Formation of large micellar aggregates before equilibrium in diluted solutions

    NASA Astrophysics Data System (ADS)

    de Moraes, J. N. B.; Figueiredo, W.

    2013-06-01

    We study the formation of premicelles for different values of the concentration of amphiphile molecules in water. Our model consists of a square lattice with water molecules occupying one cell of the lattice while the amphiphilic molecules, represented by chains of five interconnected sites, occupy five cells of the lattice. We perform Monte Carlo simulations in the NVT ensemble, for a fixed temperature and different concentration of amphiphiles, ranging from below to above the critical micelle concentration. We start our simulations from a monomeric state and follow in time all the aggregates sizes until the equilibrium state is reached. We pay particular attention to two aggregate sizes, one related to the minimum and the other to the maximum of the aggregate-size distribution curve obtained at equilibrium. We show that these aggregates evolve in time exhibiting a maximum concentration well before the equilibrium state, revealing the formation of premicelles. The times to reach these maximum concentrations decrease exponentially with the total concentration of the system.

  20. Dynamics of single polyelectrolyte chains in salt-free dilute solutions investigated by analytical ultracentrifugation.

    PubMed

    Cao, Zhonglin; Wu, Sha; Zhang, Guangzhao

    2015-06-28

    The dynamics of polyelectrolytes in salt-free solution is an unsolved problem. We have investigated the sedimentation and diffusion of xanthan and poly(N-methyl 4-vinyl pyridine iodide) (P4VPI) in salt-free dilute solutions by analytical ultracentrifugation (AUC) using sedimentation velocity (SV) as a function of polyelectrolyte concentration (Cp). Our study reveals two concentration regimes distinguished in either polyanion (xanthan) or polycation (P4VPI) dilute aqueous solution. When Cp is below the Debye concentration (Cd) at which the chain separation (d) is close to the debye length (lD), the interchain electrostatic repulsion is negligible, and the reciprocal apparent sedimentation coefficient (1/s), apparent diffusion coefficient (D) or reciprocal apparent molecular weight (1/Mw) is linearly related to Cp. In the range Cp > Cd with d < lD, the interchain electrostatic repulsion is present, and the dynamics of polyelectrolytes becomes complex. The real sedimentation coefficient (s0), the diffusion coefficient (D0) and the molecular weight (Mw,0) of the single polyelectrolyte chain in salt-free dilute solution can be obtained by extrapolating the concentration to zero. The present study reveals that the complex dynamics of polyelectrolytes in salt-free dilute solutions arises due to the interchain electrostatic repulsion.

  1. Pinch-off dynamics, extensional viscosity and relaxation time of dilute and ultradilute aqueous polymer solutions

    NASA Astrophysics Data System (ADS)

    Biagioli, Madeleine; Dinic, Jelena; Jimenez, Leidy Nallely; Sharma, Vivek

    Free surface flows and drop formation processes present in printing, jetting, spraying, and coating involve the development of columnar necks that undergo spontaneous surface-tension driven instability, thinning, and pinch-off. Stream-wise velocity gradients that arise within the thinning neck create and extensional flow field, which induces micro-structural changes within complex fluids that contribute elastic stresses, changing the thinning and pinch-off dynamics. In this contribution, we use dripping-onto-substrate (DoS) extensional rheometry technique for visualization and analysis of the pinch-off dynamics of dilute and ultra-dilute aqueous polyethylene oxide (PEO) solutions. Using a range of molecular weights, we study the effect of both elasticity and finite extensibility. Both effective relaxation time and the transient extensional viscosity are found to be strongly concentration-dependent even for highly dilute solutions.

  2. Modeling of DNA thermophoresis in dilute solutions using the non-equilibrium thermodynamics approach

    NASA Astrophysics Data System (ADS)

    Eslamian, Morteza; Saghir, M. Ziad

    2012-03-01

    Our previous approach on thermodiffusion modeling of dilute polymer solutions is extended to dilute DNA solutions. The model is based on linear non-equilibrium thermodynamics and the concept of Eyring's activation energy of viscous flow to estimate the Soret coefficient in thermophoresis of macromolecules that are not in liquid phase. The net heat of transport of single- and double-stranded DNA molecules, which are in solid state, are replaced by the activation energy of viscous flow of liquid alkanes with comparable molecular weights. The proposed formula is tested against available experimental data and qualitative agreement is observed. For double-stranded DNA molecules, the experimental data are scattered and the model can qualitatively predict the data, whereas for single-stranded DNA experiments in the infinite dilution model, for which the model is prescribed, a very good agreement is observed.

  3. Visualizing phase transition behavior of dilute stimuli responsive polymer solutions via Mueller matrix polarimetry.

    PubMed

    Narayanan, Amal; Chandel, Shubham; Ghosh, Nirmalya; De, Priyadarsi

    2015-09-15

    Probing volume phase transition behavior of superdiluted polymer solutions both micro- and macroscopically still persists as an outstanding challenge. In this regard, we have explored 4 × 4 spectral Mueller matrix measurement and its inverse analysis for excavating the microarchitectural facts about stimuli responsiveness of "smart" polymers. Phase separation behavior of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and pH responsive poly(N,N-(dimethylamino)ethyl methacrylate) (PDMAEMA) and their copolymers were analyzed in terms of Mueller matrix derived polarization parameters, namely, depolarization (Δ), diattenuation (d), and linear retardance (δ). The Δ, d, and δ parameters provided useful information on both macro- and microstructural alterations during the phase separation. Additionally, the two step action ((i) breakage of polymer-water hydrogen bonding and (ii) polymer-polymer aggregation) at the molecular microenvironment during the cloud point generation was successfully probed via these parameters. It is demonstrated that, in comparison to the present techniques available for assessing the hydrophobic-hydrophilic switch over of simple stimuli-responsive polymers, Mueller matrix polarimetry offers an important advantage requiring a few hundred times dilute polymer solution (0.01 mg/mL, 1.1-1.4 μM) at a low-volume format. PMID:26287499

  4. Improved cryopreservation by diluted vitrification solution with supercooling-facilitating flavonol glycoside.

    PubMed

    Kami, Daisuke; Kasuga, Jun; Arakawa, Keita; Fujikawa, Seizo

    2008-12-01

    The effect of kaempferol-7-O-glucoside (KF7G), one of the supercooling-facilitating flavonol glycosides which was originally found in deep supercooling xylem parenchyma cells of the katsura tree and was found to exhibit the highest level of supercooling-facilitating activity among reported substances, was examined for successful cryopreservation by vitrification procedures, with the aim of determining the possibility of using diluted vitrification solution (VS) to reduce cryoprotectant toxicity and also to inhibit nucleation at practical cooling and rewarming by the effect of supplemental KF7G. Examination was performed using shoot apices of cranberry and plant vitrification solution 2 (PVS2) with dilution. Vitrification procedures using the original concentration (100%) of PVS2 caused serious injury during treatment with PVS2 and resulted in no regrowth after cooling and rewarming (cryopreservation). Dilution of the concentration of PVS2 to 75% or 50% (with the same proportions of constituents) significantly reduced injury by PVS2 treatment, but regrowth was poor after cryopreservation. It is thought that dilution of PVS2 reduced injury by cryoprotectant toxicity, but such dilution caused nucleation during cooling and/or rewarming, resulting in poor survival. On the other hand, addition of 0.5mg/ml (0.05% w/v) KF7G to the diluted PVS2 resulted in significantly (p<0.05) higher regrowth rates after cryopreservation. It is thought that addition of supercooling-facilitating KF7G induced vitrification even in diluted PVS2 probably due to inhibition of ice nucleation during cooling and rewarming and consequently resulted in higher regrowth. The results of the present study indicate the possibility that concentrations of routinely used VSs can be reduced by adding supercooling-facilitating KF7G, by which more successful cryopreservation might be achieved for a wide variety of biological materials.

  5. Aggregation in dilute aqueous tert-butyl alcohol solutions: Insights from large-scale simulations

    NASA Astrophysics Data System (ADS)

    Gupta, Rini; Patey, G. N.

    2012-07-01

    possible nature of microheterogeneity in dilute TBA-water solutions, and of the associated long correlation lengths. It is clear that system size can be a very important factor in simulations of these solutions, and must be taken into account in the evaluation and development of TBA-water force fields.

  6. Adsorption of n-butanol from dilute aqueous solution with grafted calixarenes.

    PubMed

    Thompson, Anthony B; Cope, Sydney J; Swift, T Dallas; Notestein, Justin M

    2011-10-01

    Materials were synthesized for the recovery of n-butanol from dilute aqueous solutions, as may be useful for applications in biofuel-water separations. These materials are composed of hydrophobic, cavity-containing calixarenes covalently bound directly to porous, hydrophilic silica supports through a Si linker atom rather than a flexible organic linker, as is common, at surface coverages of up to ∼0.25 calixarenes/nm(2) (∼250 μmol calix/g matl). The calixarene ring size, upper rim groups, bridging group (calixarene vs thiacalixarene), and surface density were varied. The materials were characterized by NMR, UV-vis, and TGA. The absolute butanol uptake reached ∼0.16 mmol butanol per gram of material at equilibrium concentrations below 0.12 M and increased monotonically with the calixarene surface density. The background adsorption onto the silica surface was small at high calixarene loading. At 298 K, the free energy of adsorption in the calixarene cavities became more favorable by 3 kJ/mol as the surface area of the hydrophobic calixarene upper rim groups increased from H to methyl to tert-butyl, consistent with adsorption driven by van der Waals interactions. A thiacalix[4]arene-SiO(2) material, containing polarizable sulfur bridges and a larger, more conformationally mobile calixarene structure, had slightly stronger adsorption still. All materials except this thiacalixarene exhibited fully reversible adsorption into solution. As a representative material, the adsorption of n-butanol from aqueous solution at a tert-butylcalix[4]arene site was accompanied by a negligible enthalpy change but a small, favorable entropy change of +50 ± 20 J/mol/K, indicating that adsorption is driven by desolvation. Butanol desorbed from tert-butylcalix[4]arene materials at ∼150 °C into the gas phase, well within the range of stability of calixarenes (<300 °C), indicating that these materials have promise as regenerable adsorbents.

  7. Analytical modeling of solute redistribution during the initial unsteady unidirectional solidification of binary dilute alloys

    NASA Astrophysics Data System (ADS)

    Nastac, Laurentiu

    1998-09-01

    Existing analytical models for calculating solute redistribution during the initial transient (unsteady) unidirectional solidification with an axially moving boundary of binary dilute alloys were reviewed. The analytical solution obtained by Smith, Tiller, Rutter (STR) [Can. J. Phys. 33 (1955) 723] for semi-infinite domains was derived independently in this work. In obtaining the solution, STR used Laplace transform technique. In this work, it was rigorously proved by using Laplace transform, nondimensional analysis, and by eliminating the advection term in Eq. (1), that the analytical solution found by STR is indeed "exact" and "unique" under the stated assumptions. A thorough comparison between the exact solution and some approximate solutions is provided for partition distribution coefficients smaller and larger than one. Transient and quasi-steady-state results obtained with the exact analytical solution for segregation profiles in the liquid and at the solid/liquid interface, liquid concentration gradient at the solid/liquid interface, and solutal boundary layer are discussed in details. The size of the initial transient region is calculated. The exact solution is then applied to investigate based on thermodynamic arguments the instability of the solid/liquid interface during the initial solidification regime of dilute alloys.

  8. Ultrafast photogeneration of charged polarons on conjugated polymer chains in dilute solution

    NASA Astrophysics Data System (ADS)

    Miranda, Paulo B.; Moses, Daniel; Heeger, Alan J.

    2004-08-01

    Ultrafast photoinduced absorption by infrared-active vibrational modes is used to study the photogeneration of polarons on semiconducting polymer chains in dilute solutions and in solid films of a soluble derivative of poly(para-phenylene vinylene). In dilute solutions, polaron pairs are photogenerated on the conjugated polymer within less than 250fs with quantum efficiencies ϕch˜3% , about one-third of that for solid films of the same polymer. The excitation spectra of ϕch for both solutions and films show that ϕch is weakly dependent on photon energy between 2.2eV (the onset of absorption) and 4.7eV . The recombination dynamics of polarons is very fast and highly dependent on the excitation density for polymer films, but it is significantly slower and less sensitive to pump intensity for the semiconducting polymer in dilute solution. We conclude that the positive and negative polarons on a single chain in solution are typically separated by hundreds of monomer repeat units and that their one-dimensional diffusion along the chain is inhibited by the intervening excitons. This, together with the suppression of interchain recombination, explains the surprisingly slower polaron recombination in isolated chains.

  9. Lithium chloride ionic association in dilute aqueous solution: a constrained molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Zhang, Zhigang; Duan, Zhenhao

    2004-02-01

    Constrained molecular dynamics simulations were carried out to investigate the lithium chloride ionic associations in dilute aqueous solutions over a wide temperature range. Solvent mediated potentials of mean force have been carefully calculated at different thermodynamic conditions. Two intermediate states of ionic association can be well identified with an energy barrier from the oscillatory free energy profile. Clear pictures for the microscopic association structures are presented with a remarkable feature of strong hydration effect of lithium ion and the bridging role of its hydrating complex. Experimental association constants have been reasonably reproduced and a general trend of the increasing ionic association at high temperatures and low densities was observed. Additional simulations with different numbers of water molecules have been performed to check the possible artifacts introducing from periodic and finite size effects and confirm the reliability of our simulation results. Marginal differences of the simulated curves are believed to result from the significant compensation and canceling effect between the bare ionic forces and solvent induced mean force. Finally we confirmed the importance of accurate descriptions of dielectric properties of solvent in the ionic association study.

  10. Solvent controlled ion association in structured copolymers: Molecular dynamics simulations in dilute solutions

    NASA Astrophysics Data System (ADS)

    Aryal, Dipak; Perahia, Dvora; Grest, Gary S.

    2015-09-01

    Tailoring the nature of individual segments within ion containing block co-polymers is one critical design tool to achieve desired properties. The local structure including the size and distribution of the ionic blocks, as well as the long range correlations, are crucial for their transport ability. Here, we present molecular dynamics simulations on the effects of varying the concentrations of the ionizable groups on the conformations of pentablock ionomer that consist of a center block of ionic sulfonated styrene tethered to polyethylene and terminated by a bulky substituted styrene in dilute solutions. Sulfonation fractions f (0 ≤ f ≤ 0.55), spanning the range from ionomer to polyelectrolytes, were studied. Results for the equilibrium conformation of the chains in water and a 1:1 mixture of cyclohexane and heptane are compared to that in implicit poor solvents with dielectric constants ɛ = 1.0 and 77.73. In water, the pentablock collapses with the sulfonated groups on the outer surface. As f increases, the ionic, center block increasingly segregates from the hydrophobic regions. In the 1:1 mixture of cyclohexane and heptane, the flexible blocks swell, while the center ionic block collapses for f > 0. For f = 0, all blocks swell. In both implicit poor solvents, the pentablock collapses into a nearly spherical shape for all f. The sodium counterions disperse widely throughout the simulation cell for both water and ɛ = 77.73, whereas for ɛ = 1.0 and mixture of cyclohexane and heptane, the counterions largely condense onto the collapsed pentablock.

  11. Dilution Confusion: Conventions for Defining a Dilution

    ERIC Educational Resources Information Center

    Fishel, Laurence A.

    2010-01-01

    Two conventions for preparing dilutions are used in clinical laboratories. The first convention defines an "a:b" dilution as "a" volumes of solution A plus "b" volumes of solution B. The second convention defines an "a:b" dilution as "a" volumes of solution A diluted into a final volume of "b". Use of the incorrect dilution convention could affect…

  12. Rheological behaviors in the regimes from dilute to concentrated in cellulose solutions dissolved at low temperature.

    PubMed

    Lue, Ang; Zhang, Lina

    2009-05-13

    Cellulose was dissolved rapidly in 9.5 wt.-% NaOH/4.5 wt.-% thiourea aqueous solution pre-cooled to -5 degrees C to prepare cellulose solution with different concentrations. The rheological properties of the cellulose solutions in wide concentration regimes from dilute (0.008 wt.-%) to concentrated (4.0 wt.-%) at 25 degrees C were investigated. On the basis of data from the steady-shear flow test, the critical overlap (c*), the entanglement (c(e)) and the gel (c(g)) concentrations of the cellulose solution at 25 degrees C were determined, respectively, to be 0.10 wt.-%, 0.53 wt.-% and 2.50 wt.-%, in accordance with the results of storage modulus (G') versus c by dynamic test. Moreover, the Cox-Merz deviation at relatively low concentrations was in good agreement with the micro-gel particles in dilute regime. As the cellulose concentration increased, a homogeneous 3-dimensional network formed in the cellulose solution in the concentrated regime, and further increasing of the concentration led to micro-phase separation as determined by the time-temperature superposition (tTS). So far, this complex cellulose solution has been successfully described by the concentration regime theory for the first time, and the relatively molecular morphologies in each regime have been determined, providing useful information for the applications of the cellulose solution systems. PMID:19039777

  13. Capillary electrophoretic separation of DNA restriction fragments using dilute polymer solutions

    SciTech Connect

    Braun, B.; Blanch, W.; Prausnitz, J.M.

    1997-02-01

    Because the mechanism of DNA separation in capillary electrophoresis is not well understood, selection of polymers is a {open_quotes}trial-and-error{close_quotes} procedure. We investigated dilute-solution DNA separations by capillary electrophoresis using solutions of four polymers that differ in size, shape and stiffness. Hydroxyethylcellulose of high molecular weight provides excellent separation of large DNA fragments (2027 bp - 23130 bp). Polyvinylpyrrolidone separates DNA from 72 bp to 23 kbp and star-(polyethylene oxide), like linear poly (ethylene oxide), provides separation of fragments up to 1353 bp.

  14. Total body water and lean body mass estimated by ethanol dilution

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Myhre, L. G.; Venters, M. D.; Luft, U. C.

    1977-01-01

    A method for estimating total body water (TBW) using breath analyses of blood ethanol content is described. Regression analysis of ethanol concentration curves permits determination of a theoretical concentration that would have existed if complete equilibration had taken place immediately upon ingestion of the ethanol; the water fraction of normal blood may then be used to calculate TBW. The ethanol dilution method is applied to 35 subjects, and comparison with a tritium dilution method of determining TBW indicates that the correlation between the two procedures is highly significant. Lean body mass and fat fraction were determined by hydrostatic weighing, and these data also prove compatible with results obtained from the ethanol dilution method. In contrast to the radioactive tritium dilution method, the ethanol dilution method can be repeated daily with its applicability ranging from diseased individuals to individuals subjected to thermal stress, strenuous exercise, water immersion, or the weightless conditions of space flights.

  15. Modeling Sucrose Hydrolysis in Dilute Sulfuric Acid Solutions at Pretreatment Conditions for Lignocellulosic Biomass

    SciTech Connect

    Bower, S.; Wickramasinghe, R.; Nagle, N. J.; Schell, D. J.

    2008-01-01

    Agricultural and herbaceous feedstocks may contain appreciable levels of sucrose. The goal of this study was to evaluate the survivability of sucrose and its hydrolysis products, fructose and glucose, during dilute sulfuric acid processing at conditions typically used to pretreat lignocellulose biomass. Solutions containing 25 g/l sucrose with 0.1-2.0% (w/w) sulfuric acid concentrations were treated at temperatures of 160-200 C for 3-12 min. Sucrose was observed to completely hydrolyze at all treatment conditions. However, appreciable concentrations of fructose and glucose were detected and glucose was found to be significantly more stable than fructose. Different mathematical approaches were used to fit the kinetic parameters for acid-catalyzed thermal degradation of these sugars. Since both sugars may survive dilute acid pretreatment, they could provide an additional carbon source for production of ethanol and other bio-based products.

  16. Three-terminal capacitance cell for stopped-flow measurements of very dilute solutions

    NASA Astrophysics Data System (ADS)

    Tjahjono, Martin; Davis, Thomas; Garland, Marc

    2007-02-01

    A capacitance cell has been designed, constructed, and tested for stopped-flow measurements of very dilute low-relative permittivity liquid solutions. The capacitance cell utilizes a three-terminal design and is connected to ultrahigh sensitivity capacitance bridge. The cell was designed for operating conditions T ≈243.15-373.15K and P ≈0-1MPa and tested with pure anhydrous cyclohexane and with dilute acetone/cyclohexane solutions at 298.15K and 0.1MPa under an argon blanket in a thermostated bath with a temperature variation of <0.001K. Details of the design and materials of construction are reported. The measured relative permittivity of cyclohexane was 2.015 565, in agreement with the literature, and the long term variation of the measurement was ±5×10-6. The relative permittivities of the acetone/cyclohexane solutions were very linear (R2=0.9997) in the measured interval of 0.001-0.008mole fraction. These measurements confirm that the design specifications for stability and resolution/sensitivity of better than 1×10-5 have been realized. Finally, the present online capacitance cell was connected online to an ultrasensitive densitometer and ultrasensitive refractometer and binary acetone/cyclohexane solutions were measured. The measurements of density, refractive index, and relative permittivity were combined to provide a dipole moment of acetone of 2.750±0.005D, which is in good agreement with literature.

  17. Dilute nitric or nitrous acid solution containing halide ions as effective media for pure gold dissolution.

    PubMed

    Hojo, Masashi; Yamamoto, Masahiko; Okamura, Kei

    2015-08-14

    The greatly enhanced oxidation ability of dilute aqueous nitric acid (0.10-2.0 mol L(-1)) containing bromide and iodide salts as well as chloride salts has been examined based on the dissolution kinetics of pure gold at 30-60 °C. It has been found that bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol L(-1) HNO3 solution containing 1.0-5.0 mol L(-1) NaBr and the dissolution rate constant, log(k/s(-1)), increases linearly (from -5.78 to -4.52) with the increasing NaBr concentration. The addition of organic solvents, such as acetonitrile and acetic acid, causes acceleration of gold dissolution in LiBr and NaBr solutions. With increasing MeCN contents, for instance, the log(k/s(-1)) value of 0.10 mol L(-1) HNO3 solution containing 2.0 mol L(-1) NaBr increases linearly from -5.30 to -4.61 at 30% (v/v) MeCN. The bromide salts affect the gold dissolution rate constant in the order of KBr < NaBr < LiBr < CaBr2. With increasing NaI concentration (0.20-3.0 mol L(-1)), some acceleration in log(k/s(-1)) of 0.50 or 1.0 mol L(-1) HNO3 solution has been observed; however, the slope of acceleration as the function of NaI concentration is much smaller than that of NaCl or NaBr. The gold dissolution ability has been examined also for nitrous acid containing chloride and bromide ions at 35 °C. The NaNO2 solution containing twice or more amounts of HX (X = Cl, Br) gives the maximum efficiency for gold dissolution, according to the log(k/s(-1)) values of the mixed solutions of NaNO2 (0.10-2.0 mol L(-1)) and HX of various concentrations. The influence of oxidation by dilute nitric and nitrous acids on the gold dissolution is discussed from the standpoint of the redox potentials in "modified" aqueous solutions and not of the changes in the activity coefficients of ions.

  18. Comprehensive Water-Efficiency Solutions

    SciTech Connect

    McMordie Stoughton, Kate

    2015-07-15

    Energy performance contracts can be an effective way to integrate comprehensive water-efficient technologies and solutions into energy efficiency projects. Current practices often miss key opportunities to incorporate a full suite of water measures primarily because a comprehensive approach is not taken in the assessment. This article provides information on how to develop a comprehensive water project that leads to innovative solutions and potential for large water reduction.

  19. Dilute solution properties of canary seed (Phalaris canariensis) starch in comparison to wheat starch.

    PubMed

    Irani, Mahdi; Razavi, Seyed M A; Abdel-Aal, El-Sayed M; Hucl, Pierre; Patterson, Carol Ann

    2016-06-01

    Dilute solution properties of an unknown starch are important to understand its performance and applications in food and non-food industries. In this paper, rheological and molecular properties (intrinsic viscosity, molecular weight, shape factor, voluminosity, conformation and coil overlap parameters) of the starches from two hairless canary seed varieties (CO5041 & CDC Maria) developed for food use were evaluated in the dilute regime (Starch dispersions in DMSO (0.5g/dl)) and compared with wheat starch (WS). The results showed that Higiro model is the best among five applied models for intrinsic viscosity determination of canary seed starch (CSS) and WS on the basis of coefficient of determination (R(2)) and root mean square error (RMSE). WS sample showed higher intrinsic viscosity value (1.670dl/g) in comparison to CSS samples (1.325-1.397dl/g). Berry number and the slope of master curve demonstrated that CSS and WS samples were in dilute domain without entanglement occurrence. The shape factor suggested spherical and ellipsoidal structure for CO5041 starch and ellipsoidal for CDC Maria starch and WS. The molecular weight, coil radius and coil volume of CSSs were smaller than WS. The behavior and molecular characterization of canary seed starch showed its unique properties compared with wheat starch.

  20. Rate coefficients of the initial steps of radiation induced oligomerization of acrylates in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Wojnárovits, László; Takács, Erzsébet

    1999-08-01

    The OH radical induced oligomerization in dilute aqueous solution of ethyl- and 2-hydroxypropyl acrylate, methyl- and 2-hydroxypropyl methacrylate, acrylamide and methacrylamide, ethyl-fumarate and maleate was investigated by pulse- and steady-state radiolysis. In pulse radiolysis the reactions were observed by measuring the absorbance of the α-carboxyalkyl type radicals. At low concentration (⩽1 mmol dm -3) the radicals decay in self-termination. At higher concentration there is a significant deviation from the simple second order behavior due to oligomerization. Computer programs were used to calculate the rate coefficients of propagation and termination at the beginning of oligomerization.

  1. An investigation of the critical liquid-vapor properties of dilute KCl solutions

    USGS Publications Warehouse

    Potter, R.W.; Babcock, R.S.; Czamanske, G.K.

    1976-01-01

    The three parameters that define the critical point, temperature, pressure, and volume have been experimentally determined by means of filling studies in a platinum-lined system for five KCl solutions ranging from 0.006 to 0.568 m. The platinum-lined vessels were used to overcome the problems with corrosion experienced by earlier workers. The critical temperature (tc), pressure (Pc), and volume (Vc) were found to fit the equations {Mathematical expression} from infinite dilution to 1.0 m. ?? 1976 Plenum Publishing Corporation.

  2. "Structure-making" ability of Na+ in dilute aqueous solution: an ONIOM-XS MD simulation study.

    PubMed

    Sripa, Pattrawan; Tongraar, Anan; Kerdcharoen, Teerakiat

    2013-02-28

    An ONIOM-XS MD simulation has been performed to characterize the "structure-making" ability of Na(+) in dilute aqueous solution. The region of most interest, i.e., a sphere that includes Na(+) and its surrounding water molecules, was treated at the HF level of accuracy using LANL2DZ and DZP basis sets for the ion and waters, respectively, whereas the rest of the system was described by classical pair potentials. Detailed analyzes of the ONIOM-XS MD trajectories clearly show that Na(+) is able to order the structure of waters in its surroundings, forming two prevalent Na(+)(H(2)O)(5) and Na(+)(H(2)O)(6) species. Interestingly, it is observed that these 5-fold and 6-fold coordinated complexes can convert back and forth with some degrees of flexibility, leading to frequent rearrangements of the Na(+) hydrates as well as numerous attempts of inner-shell water molecules to interchange with waters in the outer region. Such a phenomenon clearly demonstrates the weak "structure-making" ability of Na(+) in aqueous solution.

  3. Scale-up of osmotic membrane bioreactors by modeling salt accumulation and draw solution dilution using hollow-fiber membrane characteristics and operation conditions.

    PubMed

    Kim, Suhan

    2014-08-01

    A full-scale osmotic membrane bioreactor (OMBR) model was developed to simulate salt accumulation, draw solution (DS) dilution, and water flux over the hollow-fiber membrane length. The model uses the OMBR design parameters, DS properties, and forward osmosis (FO) membrane characteristics obtained from lab-scale tests. The modeling results revealed a tremendous water flux decline (10→0.82LMH) and short solids retention time (SRT: 5days) due to salt accumulation and DS dilution when OMBR is scaled up using commercially available DS and FO membrane. Simulated water flux is a result of interplay among reverse salt flux, internal and external concentration polarization (ICP and ECP). ECP adversely impacts water flux considerably in full-scale OMBR although it is often ignored in previous works. The OMBR model makes it possible to select better DS properties (higher flow rate and salt concentration) and FO membranes with higher water flux propensity in full-scale operation.

  4. Scale-up of osmotic membrane bioreactors by modeling salt accumulation and draw solution dilution using hollow-fiber membrane characteristics and operation conditions.

    PubMed

    Kim, Suhan

    2014-08-01

    A full-scale osmotic membrane bioreactor (OMBR) model was developed to simulate salt accumulation, draw solution (DS) dilution, and water flux over the hollow-fiber membrane length. The model uses the OMBR design parameters, DS properties, and forward osmosis (FO) membrane characteristics obtained from lab-scale tests. The modeling results revealed a tremendous water flux decline (10→0.82LMH) and short solids retention time (SRT: 5days) due to salt accumulation and DS dilution when OMBR is scaled up using commercially available DS and FO membrane. Simulated water flux is a result of interplay among reverse salt flux, internal and external concentration polarization (ICP and ECP). ECP adversely impacts water flux considerably in full-scale OMBR although it is often ignored in previous works. The OMBR model makes it possible to select better DS properties (higher flow rate and salt concentration) and FO membranes with higher water flux propensity in full-scale operation. PMID:24746768

  5. Evidence for dilution of deep, confined ground water by vertical recharge of isotopically heavy Pleistocene water

    SciTech Connect

    Siegel, D.I. )

    1991-05-01

    New analyses of the isotopic composition of water, {sup 14}C-dating of dissolved inorganic carbon, and order-of-magnitude Darcy calculations suggest that a dilute body of water, trending north-south in the Cambrian-Ordovician aquifer of Iowa, was emplaced as vertical recharge of Pleistocene-age water from the base of the Des Moines lobe of late Wisconsin time. The recharge occurred through more than 300 m of overlaying Silurian to Mississippian age rocks. The {delta}{sup 18}O values range from {minus}10{per thousand} to {minus}9{per thousand} for the dilute water body and are consistent with a mixture of Des Moines lobe meltwater and precipitation found today in the north-central US. These results suggest that (1) the climate at the end of the last glaciation was mild and (2) a ground-water stable isotope signature similar to that of modern precipitation in an aquifers recharge area is not a priori evidence for relatively recent recharge.

  6. Solution by dilution?--A review on the pollution status of the Yangtze River.

    PubMed

    Floehr, Tilman; Xiao, Hongxia; Scholz-Starke, Björn; Wu, Lingling; Hou, Junli; Yin, Daqiang; Zhang, Xiaowei; Ji, Rong; Yuan, Xingzhong; Ottermanns, Richard; Roß-Nickoll, Martina; Schäffer, Andreas; Hollert, Henner

    2013-10-01

    The Yangtze River has been a source of life and prosperity for the Chinese people for centuries and is a habitat for a remarkable variety of aquatic species. But the river suffers from huge amounts of urban sewage, agricultural effluents, and industrial wastewater as well as ship navigation wastes along its course. With respect to the vast amounts of water and sediments discharged by the Yangtze River, it is reasonable to ask whether the pollution problem may be solved by simple dilution. This article reviews the past two decades of published research on organic pollutants in the Yangtze River and several adjacent water bodies connected to the main stream, according to a holistic approach. Organic pollutant levels and potential effects of water and sediments on wildlife and humans, measured in vitro, in vivo, and in situ, were critically reviewed. The contamination with organic pollutants, including polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans, polybrominated diphenyl ethers (PBDEs), perfluorinated compounds (PFCs), and others, of water and sediment along the river was described. Especially Wuhan section and the Yangtze Estuary exhibited stronger pollution than other sections. Bioassays, displaying predominantly the endpoints mutagenicity and endocrine disruption, applied at sediments, drinking water, and surface water indicated a potential health risk in several areas. Aquatic organisms exhibited detectable concentrations of toxic compounds like PCBs, OCPs, PBDEs, and PFCs. Genotoxic effects could also be assessed in situ in fish. To summarize, it can be stated that dilution reduces the ecotoxicological risk in the Yangtze River, but does not eliminate it. Keeping in mind an approximately 14 times greater water discharge compared to the major European river Rhine, the absolute pollution mass transfer of the Yangtze River is of severe concern for

  7. Separation of glycols from dilute aqueous solutions via complexation with boronic acids

    SciTech Connect

    Randel, L.A.; King, C.J.

    1991-07-01

    This work examines methods of separating low molecular weight glycols from dilute aqueous solution. Extraction into conventional solvents is generally not economical, since, in the literature reviewed, distribution ratios for the two- to four-carbon glycols are all less than one. Distribution ratios can be increased, however, by incorporating into the organic phase an extracting agent that will complex with the solute of interest. The extracting agent investigated in this work is 3-nitrophenylboronic acid (NPBA). NPBA, a boric acid derivative, reversibly complexes with many glycols. The literature on complexation of borate and related compounds with glycols, including mechanistic data, measurement techniques, and applications to separation processes, provides information valuable for designing experiments with NPBA and is reviewed herein. 88 refs., 15 figs., 24 tabs.

  8. Defect and solute properties in dilute Fe-Cr-Ni austenitic alloys from first principles

    NASA Astrophysics Data System (ADS)

    Klaver, T. P. C.; Hepburn, D. J.; Ackland, G. J.

    2012-05-01

    We present results of an extensive set of first-principles density functional theory calculations of point defect formation, binding, and clustering energies in austenitic Fe with dilute concentrations of Cr and Ni solutes. A large number of possible collinear magnetic structures were investigated as appropriate reference states for austenite. We found that the antiferromagnetic single- and double-layer structures with tetragonal relaxation of the unit cell were the most suitable reference states and highlighted the inherent instabilities in the ferromagnetic states. Test calculations for the presence and influence of noncollinear magnetism were performed but proved mostly negative. We calculate the vacancy formation energy to be between 1.8 and 1.95 eV. Vacancy cluster binding was initially weak at 0.1 eV for divacancies but rapidly increased with additional vacancies. Clusters of up to six vacancies were studied and a highly stable octahedral cluster and stacking fault tetrahedron were found with total binding energies of 2.5 and 2.3 eV, respectively. The <100> dumbbell was found to be the most stable self-interstitial with a formation energy of between 3.2 and 3.6 eV and was found to form strongly bound clusters, consistent with other fcc metals. Pair interaction models were found to be capable of capturing the trends in the defect cluster binding energy data. Solute-solute interactions were found to be weak in general, with a maximal positive binding of 0.1 eV found for Ni-Ni pairs and maximum repulsion found for Cr-Cr pairs of -0.1 eV. Solute cluster binding was found to be consistent with a pair interaction model, with Ni-rich clusters being the most stable. Solute-defect interactions were consistent with Ni and Cr being modestly oversized and undersized solutes, respectively, which is exactly opposite to the experimentally derived size factors for Ni and Cr solutes in type 316 stainless steel and in the pure materials. Ni was found to bind to the vacancy and

  9. Treatment of dilute clusters of methanol and water by ab initio quantum mechanical calculations.

    PubMed

    Ruckenstein, Eli; Shulgin, Ivan L; Tilson, Jeffrey L

    2005-02-10

    Large molecular clusters can be considered as intermediate states between gas and condensed phases, and information about them can help us understand condensed phases. In this paper, ab initio quantum mechanical methods have been used to examine clusters formed of methanol and water molecules. The main goal was to obtain information about the intermolecular interactions and the structure of methanol/water clusters at the molecular level. The large clusters (CH(4)O...(H(2)O)(12) and H(2)O...(CH(4)O)(10)) containing one molecule of one component (methanol or water) and many (12, 10) molecules of the other component were considered. Møller-Plesset perturbation theory (MP2) was used in the calculations. Several representative cluster geometries were optimized, and nearest-neighbor interaction energies were calculated for the geometries obtained in the first step. The results of the calculations were compared to the available experimental information regarding the liquid methanol/water mixtures and to the molecular dynamics and Monte Carlo simulations, and good agreement was found. For the CH(4)O...(H(2)O)(12) cluster, it was shown that the molecules of water can be subdivided into two classes: (i) H bonded to the central methanol molecule and (ii) not H bonded to the central methanol molecule. As expected, these two classes exhibited striking energy differences. Although they are located almost the same distance from the carbon atom of the central methanol molecule, they possess very different intermolecular interaction energies with the central molecule. The H bonding constitutes a dominant factor in the hydration of methanol in dilute aqueous solutions. For the H(2)O...(CH(4)O)(10) cluster, it was shown that the central molecule of water has almost three H bonds with the methanol molecules; this result differs from those in the literature that concluded that the average number of H bonds between a central water molecule and methanol molecules in dilute solutions of

  10. Interatomic interactions and thermodynamic parameters in dilute solid solutions of the Ag-Au system

    NASA Astrophysics Data System (ADS)

    Bogdanov, V. I.; Bol'shov, L. A.; Korneichuk, E. A.; Popov, V. A.; Korneichuk, S. K.; Badanin, D. A.

    2015-07-01

    The thermodynamic parameters of interaction and the enthalpy parameters are of fundamental importance in the theory of solutions, i.e., the coefficients of the expansion of partial excess thermodynamic functions into series in terms of the concentrations of the dissolved components. In the approximation of pairwise interactions between the impurity atoms in the solution, the above parameters can be computed using the methods of the density-functional theory in the electron theory of alloys. As an example, the substitutional solid solutions of Au in Ag have been chosen, which are formed by atoms of the components with close chemical properties, in which the deformation interactions should be small, and in which there is no need to take into account the complex magnetic contributions to the pair potentials. The total energy of the dilute solution of Au in Ag and the contributions from the chemical and strain-induced interactions to the potentials of pairwise interactions are calculated up to the seventh coordination shell. Quite satisfactory agreement with the thermodynamic parameters obtained from the experimental data has been obtained.

  11. Transport properties of dilute α -Fe (X ) solid solutions (X = C, N, O)

    NASA Astrophysics Data System (ADS)

    Schuler, Thomas; Nastar, Maylise

    2016-06-01

    We extend the self-consistent mean field (SCMF) method to the calculation of the Onsager matrix of Fe-based interstitial solid solutions. Both interstitial jumps and substitutional atom-vacancy exchanges are accounted for. A general procedure is introduced to split the Onsager matrix of a dilute solid solution into intrinsic cluster Onsager matrices, and extract from them flux-coupling ratios, mobilities, and association-dissociation rates for each cluster. The formalism is applied to vacancy-interstitial solute pairs in α -Fe (V X pairs, X = C, N, O), with ab initio based thermodynamic and kinetic parameters. Convergence of the cluster mobility contribution gives a controlled estimation of the cluster definition distance, taking into account both its thermodynamic and kinetic properties. Then, the flux-coupling behavior of each V X pair is discussed, and qualitative understanding is achieved from the comparison between various contributions to the Onsager matrix. Also, the effect of low-activation energy second-nearest-neighbor interstitial solute jumps around a vacancy on these results is addressed.

  12. Water-based adhesives with tailored hydrophobic association: dilution resistance and improved setting behavior.

    PubMed

    Dundua, Alexander; Landfester, Katharina; Taden, Andreas

    2014-11-01

    Hydrophobic association and stimuli-responsiveness is a powerful tool towards water-based adhesives with strongly improved properties, which is demonstrated based on the example of hydrophobically modified alkali-soluble latexes (HASE) with modulated association. Their rheological properties are highly tunable due to the hydrophobic domains that act as physical crosslinking sites of adjustable interaction strength. Ethanol, propanol, and butanol are used as water-soluble model additives with different hydrophobicity in order to specifically target the association sites and impact the viscoelastic properties and stimuli-responsiveness. The rheological and mechanical property response upon dilution with water can be tailored, and dilution-resistant or even dilution-thickening systems are obtained. The investigations are of high importance for water-based adhesives, as our findings provide insight into general structure-property relationships to improve their setting behavior, especially upon contact with wet substrates.

  13. Impairment of Temperate Bacteriophage Adsorption by Brief Treatment of Escherichia coli with Dilute Solutions of Ethylenediaminetetraacetate

    PubMed Central

    Protass, Jay J.; Korn, David

    1966-01-01

    Protass, Jay J. (National Institute of Arthritis and Metabolic Diseases, Bethesda, Md.), and David Korn. Impairment of temperate bacteriophage adsorption by brief treatment of Escherichia coli with dilute solutions of ethylenediaminetetraacetate. J. Bacteriol. 91:143–147. 1966.—Cells of Escherichia coli K-12 treated for 2 min with 2 × 10−4m ethylenediaminetetraacetate (EDTA) are unable to adsorb the temperate bacteriophages λvir and 434 but show no impairment of their ability to adsorb T-even phages or T5. This finding is consistent with the hypothesis that there are basic structural differences between the cell-wall receptors involved in the adsorption of the temperate and T classes of coliphages. PMID:16562097

  14. Chain aggregation in dilute solutions of poly(methyl methacrylate) below the phase-separation temperature

    NASA Astrophysics Data System (ADS)

    Nakagawa, Tomohide; Nakamura, Yoshiki; Sasaki, Naoki; Nakata, Mitsuo

    2001-03-01

    For dilute solutions of poly(methyl methacrylate) in isoamyl acetate with the molecular weight Mw=4.4×106, the phase-separation process was studied by static light-scattering measurements. The dilute solutions in the concentration range from 1.4×10-4 to 3.8×10-4 g/cm3 were quenched to about 16 K below the phase-separation temperature, and the aggregation processes of polymer chains were measured over a period of several hours. By analyzing the light-scattering data with the Guinier plot, the weight-averaged molecular weight w and z-averaged square radius 1/2z for clusters of polymer chains were determined as a function of time t(min) and concentration c (g/cm3). The growth of clusters was represented by the exponential forms w/M(0)=egct and z/R2(0)=ehct as a function of ct, where M(0) and R2(0) were the values at t=0, and the constants g and h were determined to be g=11.6 and h=7.5. A double-logarithmic plot of w versus 1/2z yielded a straight line with the slope D=3.06+/-0.02. These characteristic features of the chain aggregation process were compared with the Smoluchowski equation for cluster-cluster aggregation with the collision kernel (i+j) for i-mer and j-mer. The observed slow growth of clusters was attributed to the reaction- limited cluster aggregation. The chain density in a cluster was found to increase with an increase of the cluster size, resulting in the slope D exceeding 3.

  15. The interaction of polycrystalline copper films with dilute aqueous solutions of cupric chloride

    NASA Astrophysics Data System (ADS)

    Walsh, Lois Harper

    1989-10-01

    In the electronics industry, thin films of copper deposited on substrates are used as electrically conductive paths to interconnect semiconductor devices and other computer components. The dissolution of copper in a dilute aqueous cupric chloride solution was studied to achieve an understanding of the role microstructure plays in the dissolution process. A multi-technique approach was taken using combinations of solution chemistry, computer modeling, and microstructural characterization techniques to analyze as-received samples and to monitor the dissolution process. This latter approach allowed reaction rates and activation energies to be calculated from speciation concentrations derived from computer modeling of known thermochemical reactions. In conjunction with the solution analysis, surface techniques were used to analyze the concentration distribution of the various elements after sample exposure to the etchant. The etching characteristics of the polycrystalline thin copper films are dependent on the film's microstructure. A procedure is suggested that will aid future researchers in the correlation of microstructure and dissolution characteristics of different copper samples prior to mass production of metallization for microelectronic circuits.

  16. Improving oral bioavailability of metformin hydrochloride using water-in-oil microemulsions and analysis of phase behavior after dilution.

    PubMed

    Li, Yuan; Song, Jiaqi; Tian, Ning; Cai, Jie; Huang, Meihong; Xing, Qiao; Wang, Yalong; Wu, Chuanbin; Hu, Haiyan

    2014-10-01

    Microemulsions show significant promise for enhancing the oral bioavailability of biopharmaceutics classification system (BCS) class II drugs, but how about class III drugs remains unclear. Here we employed metformin hydrochloride (MET) as the model drug and prepared drug-loaded water-in-oil (W/O) microemulsions selecting different hydrophile-lipophile balance (HLB) surfactant systems, using HLB 8 as a cut-off. We examined the phase behaviors of microemulsions after dilution and attempted to correlate these behaviors to drug oral bioavailability. ME-A, including a lower content of surfactants (35%), underwent a transition of W/O emulsion and then became a stable O/W emulsion in a light milky appearance; ME-B, in contrast, introducing a higher content of surfactants (45%), still remained transparent or semitransparent upon dilution. Unexpectedly, ME-A showed significantly higher oral bioavailability, which can be reduced by blocking the lymphatic absorption pathway. Comparatively, the AUC of ME-B is lower, close to MET solution. Both microemulsions behaved similarly in intestinal perfusion test because of the dilution before perfusion, lacking of the important phase transition of W/O emulsion. These findings suggest that W/O microemulsions improve oral bioavailability of BCS class III drug by promoting lymphatic absorption. Analyzing the phase behavior of microemulsions after dilution may help predict the drug oral bioavailability and optimize formulations.

  17. Solubilization of Tea Seed Oil in a Food-Grade Water-Dilutable Microemulsion

    PubMed Central

    Deng, Lingli; Que, Fei; Wei, Hewen; Xu, Guangwei; Dong, Xiaowei; Zhang, Hui

    2015-01-01

    Food-grade microemulsions containing oleic acid, ethanol, Tween 20, and water were formulated as a carrier system for tea seed oil (Camellia oleifera Abel.). The effect of ethanol on the phase behavior of the microemulsion system was clearly reflected in pseudo-ternary diagrams. The solubilization capacity and solubilization efficiency of tea seed oil dispersions were measured along the dilution line at a 70/30 surfactant/oil mass ratio with Tween 20 as the surfactant and oleic acid and ethanol (1:3, w/w) as the oil phase. The dispersed phase of the microemulsion (1.5% weight ratio of tea seed oil to the total amount of oil, surfactant, and tea seed oil) could be fully diluted with water without phase separation. Differential scanning calorimetry and viscosity measurements indicated that both the carrier and solubilized systems underwent a similar microstructure transition upon dilution. The dispersion phases gradually inverted from the water-in-oil phase (< 35% water) to the bicontinuous phase (40–45% water) and finally to the oil-in-water phase (> 45% water) along the dilution line. PMID:25996147

  18. Geophysical methods to support correct water sampling locations for salt dilution gauging

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2014-05-01

    To improve water management design, particularly in irrigation areas, it is important to evaluate the baseline state of the water resources, including canal discharge. Discharge measurements, using salt dilution gauging, are a traditional and well-documented technique. The complete mixing of salt used for dilution gauging is required for reliable measurements; this condition is difficult to test or verify and, if not fulfilled, is the largest source of uncertainty in the discharge calculation. In this paper, a geophysical technique (FERT, Fast Electrical Resistivity Tomography) is proposed for imaging the distribution of the salt plume used for dilution gauging at every point along a sampling cross-section. In this way, it is possible to check whether complete mixing has occurred. If the mixing is not complete, the image created by FERT can also provide guidance for selecting water-sampling locations in the sampling cross-section. A water multi-sampling system prototype for the simultaneous sampling of canal water at different points within the cross-section, aimed to potentially take into account concentration variability, is also proposed and tested. Preliminary results of a single test with salt dilution gauging and FERT in a real case are reported. The results show that imaging the passage of the salt plume is possible by means of geophysical controls and that this can potentially help in the selection of water sampling points.

  19. Analytical approaches to the OH radical induced degradation of sulfonamide antibiotics in dilute aqueous solutions.

    PubMed

    Sági, Gyuri; Csay, Tamás; Szabó, László; Pátzay, György; Csonka, Emil; Takács, Erzsébet; Wojnárovits, László

    2015-03-15

    By combining a large variety of analytical techniques this study aimed at elaborating methods to follow up the degradation of sulfonamides in an advanced oxidation process (AOP): irradiation with ionizing radiation in dilute aqueous solution. In this process, besides other radicals, hydroxyl radicals are produced. As pulse radiolysis experiments show the basic initial reaction is hydroxyl radical addition to the benzene ring, forming cyclohexadienyl radical intermediates. In aerated solutions these radicals transform to peroxy radicals. Among the first formed products aromatic molecules hydroxylated in the benzene rings or in some cases in the heterocyclic rings were observed by LC-MS/MS. Chemical oxygen demand (COD) measurements indicate that at the early reaction period of degradation one hydroxyl radical induces incorporation of 1.5 O atoms into the products. Comparison of the COD and TOC (total organic carbon content) results shows gradual oxidation. Simultaneously with hydroxylation ring opening also takes place. The kinetics of inorganic SO4(2-) and NH4(+) formation, analyzed by ion chromatography, is similar to the kinetics of ring degradation (UV spectroscopy), however, there is a delayed formation of NO3(-). The latter ions may be produced in oxidative degradation of smaller N containing fragments. The S atoms of the sulfonamides remain in the solution (ICP-MS measurements) after degradation, whereas some part of the N atoms leaves the solution probably in the form of N2 (total nitrogen content (TN) measurements). Degradation is accompanied by a high pH drop due to formation of SO4(2-), NO3(-) and smaller organic acids. The degradation goes through many simultaneous and consecutive reactions, and with the applied methods the different stages of degradation can be characterized.

  20. Influence of temperature, mono- and divalent cations on dilute solution properties of sage seed gum.

    PubMed

    Yousefi, A R; Razavi, Seyed M A; Khodabakhsh Aghdam, S H

    2014-06-01

    The functional properties of food hydrocolloids are remarkably affected by the quality of solvent/cosolutes and temperature in a food system. In this paper, dilute solution properties of sage seed gum (SSG) as a function of salt type (NaCl, KCl, MgCl2 and CaCl2), salt concentration (10, 50, 100 and 200mM) and temperature (25, 45 and 65°C) were investigated. Among various models, Higiro model showed a higher performance to determine intrinsic viscosity of SSG at all temperatures and cosolutes. From 25 to 65°C for every 20°C rise in temperature, intrinsic viscosity decreased about 18.99 and 63.86%, respectively. The divalent cations had more reduction effect on intrinsic viscosity than monovalet cations. More flexibility of SSG in monovalent salts solutions compared with divalent ones was observed. A high value for activation energy (2.53×10(7)J/kgmol) and chain flexibility (3046.45) of SSG was obtained, which was higher than many hydrocolloids. The shape factor of SSG macromolecules at 25-65°C was an oblate or prolate and for all used cosolutes, the shape was roughly found to be ellipsoidal.

  1. Superhydrophobic surfaces as smart platforms for the analysis of diluted biological solutions.

    PubMed

    Gentile, Francesco; Coluccio, Maria Laura; Coppedè, Nicola; Mecarini, Federico; Das, Gobind; Liberale, Carlo; Tirinato, Luca; Leoncini, Marco; Perozziello, Gerardo; Candeloro, Patrizio; De Angelis, Francesco; Di Fabrizio, Enzo

    2012-06-27

    The aim of this paper is to expound on the rational design, fabrication and development of superhydrophobic surfaces (SHSs) for the manipulation and analysis of diluted biological solutions. SHSs typically feature a periodic array or pattern of micropillars; here, those pillars were modified to incorporate on the head, at the smallest scales, silver nanoparticles aggregates. These metal nanoclusters guarantee superior optical properties and especially SERS (surface enhanced Raman scattering) effects, whereby a molecule, adsorbed on the surface, would reveal an increased spectroscopy signal. On account of their two scale-hybrid nature, these systems are capable of multiple functions which are (i) to concentrate a solution, (ii) to vehicle the analytes of interest to the active areas of the substrate and, therefore, (iii) to measure the analytes with exceptional sensitivity and very low detection limits. Forasmuch, combining different technologies, these devices would augment the performance of conventional SERS substrates and would offer the possibility of revealing a single molecule. In this work, similar SHSs were used to detect Rhodamine molecules in the fairly low atto molar range. The major application of this novel family of devices would be the early detection of tumors or other important pathologies, with incredible advances in medicine.

  2. Structural Dynamics of Star-Shaped Weak Polyelectrolytes in Dilute Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Qu, Chen; Zhu, Y. Elaine

    Weak polyelectrolyte (PE) bearing tunable charges along their backbones show great potential as ``smart'' polymer materials for diverse applications from drug delivery to energy storage. With the introduction of branched topology, the local counterion distribution in the vicinity to the polyelectrolyte segments becomes highly inhomogeneous. To experimentally investigate the interplay between structural dynamics and local electric environment of a branched polyelectrolyte, in this work we custom synthesized star-shaped poly(2-vinylpyridine) (P2VP) using reversible addition fragmentation chain transfer (RAFT) polymerization and labeled P2VP stars with pH-sensitive fluorophore precisely either in the center or periphery. By employing fluorescence correlation spectroscopy (FCS) with photon counts histogram (PCH) analysis, we observed gradual stretched-to-collapses conformational transition with increasing solution pH for both P2VP stars of different fluorophore labeling locations. However, the measured local pH, or local proton concentration, shows strong dependence of the fluorophore labeling locations. Higher electric potential yet lower ionization degree was observed in the core of P2VP star than that in the periphery. Ongoing work is carried out to examine the scaling behaviors of P2VP star sizes with varied number of arms, arm lengths and counterion concentrations in dilute aqueous solutions.

  3. A new method to determine the yield stress of diluted polymeric solutions

    NASA Astrophysics Data System (ADS)

    Soto, Enrique; Ruiz, Servando; Cordova Aguilar, Maria Soledad

    2012-11-01

    A new method to measure the yield stress for diluted polymeric solutions is presented. The tested solutions exhibit shear thinning behavior a once the critical yield stress is overcame. In rheology, these fluids are known as Herschel-Buckley. The yield stress phenomenon and its relation with bubble motion is an important issue for different industries, for example, personal care, paints and some others. As a result of the yield stress, small bubbles remain trapped in the fluid bulk, but above a critical volume, which is related with the characteristic yield stress, the bubbles flow in the liquid. In order to change the bubble volume, the liquid is placed in a cylindrical container whose pressure is decreased by a vacuum pump. The bubble growths as the pressure decreases and keeps its position until it reaches the critical volume. The bubble shape changes with volume and velocity, and a competition among surface, gravitational, inertial and viscous forces is discussed. The yield stress determined value is higher than the obtained from simple shear measurements due to the complex flow around the bubble.

  4. Understanding the Permeation of Solutes in Water Treatment Membranes

    NASA Astrophysics Data System (ADS)

    Phillip, William

    2013-03-01

    The responsible management of the world's water resources is essential to supporting human life on earth. The successful development of reverse osmosis seawater desalination makes it a crucial component in the portfolio of water supply options. However, other measures to alleviate the stresses on water supplies are necessary to responsibly and sustainably meet the worldwide demand for fresh water. Osmotically driven membrane processes (ODMP) are an emerging set of technologies that show promise in water conservation and reuse, as well as wastewater reclamation. The majority of research in the field has focused on predicting and enhancing water permeation through membranes, however, the effective operation of ODMP systems requires that the permeation of solutes across water treatment membranes be better understood. For example, the reverse flux of draw solute from the concentrated draw solution into the feed solution should be minimized. Additionally, due to the presence of solute-solute interactions that arise because of the unique geometry of ODMPs, the rejection of dilute solutes in these processes can be dramatically different than those observed in traditional pressure driven operations. In this talk, theoretical and experimental approaches are used to explore the permeation of solutes in osmotically driven membrane processes. Phenomenological models were developed that describe the forward and reverse permeation of the solutes across an asymmetric membrane in forward osmosis operation; and experiments were carried out to validate the model predictions. Using independently determined membrane transport coefficients, strong agreement between the model predictions and experimental results was observed.

  5. The Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Houser, P.; Belvedere, D.; Imam, B.; Schiffer, R.; Schlosser, C.; Gupta, H.; Welty, C.; Vörösmarty, C.; Matthews, D.; Lawford, R.

    2006-12-01

    The goal of the Water cycle Solutions Network is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend research results to augment decision support tools and meet national needs. WaterNet will engage relevant NASA water cycle research resources and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect water cycle research results (WCRs) towards the improvement of water-related Decision Support Tools (DSTs). An actionable database includes enough sufficient knowledge about its nodes and their heritage so that connections between these nodes are identifiable and robust. Recognizing the many existing highly valuable water-related science and application networks, we will focus the balance of our efforts on enabling their interoperability in a solutions network context. We will initially focus on identification, collection, and analysis of the two end points, these being the WCRs and water related DSTs. We will then develop strategies to connect these two end points via innovative communication strategies, improved user access to NASA resources, improved water cycle research community appreciation for DST requirements, improved policymaker, management and stakeholder knowledge of NASA research and application products, and improved identification of pathways for progress. Finally, we will develop relevant benchmarking and metrics, to understand the network's characteristics, to optimize its performance, and to establish sustainability. The WaterNet will deliver numerous pre-evaluation reports that will identify the pathways for improving the collective ability of the water cycle community to routinely harness WCRs that address crosscutting water cycle challenges.

  6. Study of quantitative interactions of potato and corn starch granules with ions in diluted solutions of heavy metal salts.

    PubMed

    Szymońska, Joanna; Molenda, Marcin; Wieczorek, Jerzy

    2015-12-10

    Interactions of potato and corn starch granules with ions in diluted solutions of silver, lead, copper or iron salts were investigated. It was shown experimentally that granules accumulated the cations in amounts depending on the granule structure and water content as well as a type of both metal and counter-ions present in solution. Potato starch retained almost three times more cations compared to corn starch what was proportional to the total phosphorous content in these starches. Quantity of milligrams of cations bound by 1g of starch was inversely correlated with the cation hydration. Ag(+), Pb(2+) and Cu(2+) were connected in stoichiometric amounts of moles to semicrystalline and amorphous parts of the granules. Fe(3+) ions were accumulated in higher than stoichiometric quantities mainly in granule amorphous regions. Metal ions penetrated into granules together with anions except nitrates which remained on surface of potato starch granules. Cations facilitated the starch thermal decomposition in accordance with values of their standard redox potentials. Nitrates supported this process only in the presence of base metal cations.

  7. Effect of hydrodynamic correlations on the dynamics of polymers in dilute solution

    NASA Astrophysics Data System (ADS)

    Huang, Chien-Cheng; Gompper, Gerhard; Winkler, Roland G.

    2013-04-01

    We analyze the effect of time-dependent hydrodynamic interactions on the dynamics of flexible polymers in dilute solution. In analytical calculations, the fluctuating hydrodynamics approach is adopted to describe the fluid, and a Gaussian model to represented the polymer. Simulations are performed exploiting the multiparticle collision dynamics approach, a mesoscale hydrodynamic simulation technique, to explicitly describe the fluid. Polymer center-of-mass velocity correlation functions are calculated for various polymer lengths. Similarly, segment mean square displacements are discussed and polymer diffusion coefficients are determined. Particular attention is paid to the influence of sound propagation on the various properties. The simulations reveal a strong effect of hydrodynamic interactions. Specifically, the time dependence of the center-of-mass velocity correlation functions is determined by polymer properties over a length-dependent time window, but are asymptotically solely governed by fluid correlations, with a long-time tail decaying as t-3/2. The correlation functions are heavily influenced by sound modes for short polymers, an effect which gradually disappears with increasing polymer length. We find excellent agreement between analytical and simulation results. This allows us to provide a theory-based asymptotic value for the polymer diffusion coefficient in the limit of large system sizes, which is based on a single finite-system-size simulation.

  8. Chain-length heterogeneity allows for the assembly of fatty acid vesicles in dilute solutions.

    PubMed

    Budin, Itay; Prwyes, Noam; Zhang, Na; Szostak, Jack W

    2014-10-01

    A requirement for concentrated and chemically homogeneous pools of molecular building blocks would severely restrict plausible scenarios for the origin of life. In the case of membrane self-assembly, models of prebiotic lipid synthesis yield primarily short, single-chain amphiphiles that can form bilayer vesicles only at very high concentrations. These high critical aggregation concentrations (cacs) pose significant obstacles for the self-assembly of single-chain lipid membranes. Here, we examine membrane self-assembly in mixtures of fatty acids with varying chain lengths, an expected feature of any abiotic lipid synthesis. We derive theoretical predictions for the cac of mixtures by adapting thermodynamic models developed for the analogous phenomenon of mixed micelle self-assembly. We then use several complementary methods to characterize aggregation experimentally, and find cac values in close agreement with our theoretical predictions. These measurements establish that the cac of fatty acid mixtures is dramatically lowered by minor fractions of long-chain species, thereby providing a plausible route for protocell membrane assembly. Using an NMR-based approach to monitor aggregation of isotopically labeled samples, we demonstrate the incorporation of individual components into mixed vesicles. These experiments suggest that vesicles assembled in dilute, mixed solutions are depleted of the shorter-chain-length lipid species, a finding that carries implications for the composition of primitive cell membranes. PMID:25296310

  9. Chain-Length Heterogeneity Allows for the Assembly of Fatty Acid Vesicles in Dilute Solutions

    PubMed Central

    Budin, Itay; Prwyes, Noam; Zhang, Na; Szostak, Jack W.

    2014-01-01

    A requirement for concentrated and chemically homogeneous pools of molecular building blocks would severely restrict plausible scenarios for the origin of life. In the case of membrane self-assembly, models of prebiotic lipid synthesis yield primarily short, single-chain amphiphiles that can form bilayer vesicles only at very high concentrations. These high critical aggregation concentrations (cacs) pose significant obstacles for the self-assembly of single-chain lipid membranes. Here, we examine membrane self-assembly in mixtures of fatty acids with varying chain lengths, an expected feature of any abiotic lipid synthesis. We derive theoretical predictions for the cac of mixtures by adapting thermodynamic models developed for the analogous phenomenon of mixed micelle self-assembly. We then use several complementary methods to characterize aggregation experimentally, and find cac values in close agreement with our theoretical predictions. These measurements establish that the cac of fatty acid mixtures is dramatically lowered by minor fractions of long-chain species, thereby providing a plausible route for protocell membrane assembly. Using an NMR-based approach to monitor aggregation of isotopically labeled samples, we demonstrate the incorporation of individual components into mixed vesicles. These experiments suggest that vesicles assembled in dilute, mixed solutions are depleted of the shorter-chain-length lipid species, a finding that carries implications for the composition of primitive cell membranes. PMID:25296310

  10. Chain-length heterogeneity allows for the assembly of fatty acid vesicles in dilute solutions.

    PubMed

    Budin, Itay; Prwyes, Noam; Zhang, Na; Szostak, Jack W

    2014-10-01

    A requirement for concentrated and chemically homogeneous pools of molecular building blocks would severely restrict plausible scenarios for the origin of life. In the case of membrane self-assembly, models of prebiotic lipid synthesis yield primarily short, single-chain amphiphiles that can form bilayer vesicles only at very high concentrations. These high critical aggregation concentrations (cacs) pose significant obstacles for the self-assembly of single-chain lipid membranes. Here, we examine membrane self-assembly in mixtures of fatty acids with varying chain lengths, an expected feature of any abiotic lipid synthesis. We derive theoretical predictions for the cac of mixtures by adapting thermodynamic models developed for the analogous phenomenon of mixed micelle self-assembly. We then use several complementary methods to characterize aggregation experimentally, and find cac values in close agreement with our theoretical predictions. These measurements establish that the cac of fatty acid mixtures is dramatically lowered by minor fractions of long-chain species, thereby providing a plausible route for protocell membrane assembly. Using an NMR-based approach to monitor aggregation of isotopically labeled samples, we demonstrate the incorporation of individual components into mixed vesicles. These experiments suggest that vesicles assembled in dilute, mixed solutions are depleted of the shorter-chain-length lipid species, a finding that carries implications for the composition of primitive cell membranes.

  11. Elastic turbulence in Taylor-Couette Flow of Dilute Polymeric Solutions: A Direct Numerical Simulation Study

    NASA Astrophysics Data System (ADS)

    Liu, Nansheng; Khomami, Bamin

    2011-11-01

    Despite tremendous progress in development of numerical techniques and constitutive theories for polymeric fluids in the past decade, Direct Numerical Simulation (DNS) of elastic turbulence has posed tremendous challenges to researchers engaged in developing first principles models and simulations that can accurately and robustly predict the dynamical behavior of polymeric flows. In this presentation, we report the first DNS of elastic turbulence in the Taylor-Couette (TC) flow. Specifically, our computations with prototypical constitutive equations for dilute polymeric solutions, such as the FENE-P model are capable of reproducing the essential features of the experimentally observed elastic turbulence in TC flow of this class of fluids, namely, randomly fluctuating fluid motion excited in a broad range of spatial and temporal scales, and a significant increase of the flow resistance. Moreover, the experimentally measured Power Spectral Density of radial velocity fluctuations, i.e., two contiguous regions of power-law decay, -1.1 at lower frequencies and -2.2 at high-frequencies is accurately computed. We would like to thank NSF through grant CBET-0755269 and NSFC through grant NO. 10972211 for supporting of this work.

  12. Lagrange thermodynamic potential and intrinsic variables for He-3 He-4 dilute solutions

    NASA Technical Reports Server (NTRS)

    Jackson, H. W.

    1983-01-01

    For a two-fluid model of dilute solutions of He-3 in liquid He-4, a thermodynamic potential is constructed that provides a Lagrangian for deriving equations of motion by a variational procedure. This Lagrangian is defined for uniform velocity fields as a (negative) Legendre transform of total internal energy, and its primary independent variables, together with their thermodynamic conjugates, are identified. Here, similarities between relations in classical physics and quantum statistical mechanics serve as a guide for developing an alternate expression for this function that reveals its character as the difference between apparent kinetic energy and intrinsic internal energy. When the He-3 concentration in the mixtures tends to zero, this expression reduces to Zilsel's formula for the Lagrangian for pure liquid He-4. An investigation of properties of the intrinsic internal energy leads to the introduction of intrinsic chemical potentials along with other intrinsic variables for the mixtures. Explicit formulas for these variables are derived for a noninteracting elementary excitation model of the fluid. Using these formulas and others also derived from quantum statistical mechanics, another equivalent expression for the Lagrangian is generated.

  13. Controlled formation of ag nanoparticles by means of long-chain sodium polyacrylates in dilute solution.

    PubMed

    Huber, Klaus; Witte, Thomas; Hollmann, Jutta; Keuker-Baumann, Susanne

    2007-02-01

    A new tool is presented to control formation of Ag nanoparticles. Small amounts of silver ions were added to dilute solutions of long-chain sodium polyacrylates (NaPA). Four NaPA samples covering a molar mass regime of 97 kD < or = Mw < or = 650 kD have been used. With amounts of added Ag(+) as low as 1-2% of the COO(-) groups of the polyanionic chains, significant changes could already be induced in the NaPA coils with 650 kD. If the NaPA concentration was kept below 0.1 g/L, the coils with 650 kD exhibited a significant coil shrinking in stable solutions. At larger NaPA concentrations, addition of Ag+ initiates an aggregation of the polyacrylate coils toward compact structures. Coil shrinking and aggregation was revealed by means of time-resolved static light scattering. If exposed to UV-radiation, small Ag particles formed within the shrunken anionic polyacrylate coils. The Ag nanoparticles were identified by means of an enhanced light scattering and a characteristic plasmon absorption band around 410 nm. No such Ag particle formation could be observed even at 5 times larger concentrations of Ag(+) and NaPA if the two smallest polyacrylate samples have been used under otherwise equal conditions. This molar mass sensitive response of NaPA to Ag(+)-addition suggests an interesting phenomenon: if the coil size of the NaPa chains, which act as Ag(+) collectors, is large enough, local Ag(+) concentration in these coil-shaped Ag(+) containers exceeds a critical value, and irradiation with UV generates Ag nanoparticles. PMID:17263389

  14. Measurement of solute transport in the endothelial glycocalyx using indicator dilution techniques.

    PubMed

    Gao, Lujia; Lipowsky, Herbert H

    2009-09-01

    A new method is presented to quantify changes in permeability of the endothelial glycocalyx to small solutes and fluid flow using techniques of indicator dilution. Following infusion of a bolus of fluorescent solutes (either FITC or FITC conjugated Dextran70) into the rat mesenteric circulation, its transient dispersion through post-capillary venules was recorded and analyzed offline. To represent dispersion of solute as a function of radial position in a microvessel, a virtual transit time (VTT) was calculated from the first moment of fluorescence intensity-time curves. Computer simulations and subsequent in vivo measurements showed that the radial gradient of VTT within the glycocalyx layer (Delta VTT/Delta r) may be related to the hydraulic resistance within the layer along the axial direction in a post-capillary venule and the effective diffusion coefficient within the glycocalyx. Modeling the inflammatory process by superfusion of the mesentery with 10(-7) M fMLP, Delta VTT/Delta r was found to decrease significantly from 0.23 +/- 0.08 SD s/microm to 0.18 +/- 0.09 SD s/microm. Computer simulations demonstrated that Delta VTT/Delta r is principally determined by three independent variables: glycocalyx thickness (delta), hydraulic resistivity (K(r)) and effective diffusion coefficient of the solute (D(eff)) within the glycocalyx. Based upon these simulations, the measured 20% decrease in Delta VTT/Delta r at the endothelial cell surface corresponds to a 20% increase in D(eff) over a broad range in K(r), assuming a constant thickness delta. The absolute magnitude of D(eff) required to match Delta VTT/Delta r between in vivo measurements and simulations was found to be on the order of 2.5 x 10(-3) x D(free), where D(free) is the diffusion coefficient of FITC in aqueous media. Thus the present method may provide a useful tool for elucidating structural and molecular alterations in the glycocalyx as occur with ischemia, metabolic and inflammatory events.

  15. Conformation and Phase Separation of Oligo (ethylene glycol) Grafted Polystyrene in Dilute Aqueous Solutions

    SciTech Connect

    Cheng, Gang; Melnichenko, Yuri B; Wignall, George D; Hua, Fengjun; Hong, Kunlun; Mays, Jimmy

    2007-01-01

    Temperature induced conformational changes of poly(p-oligo(ethylene glycol) styrene) (POEGS) in aqueous solutions were investigated by small angle neutron scattering (SANS), neutron transmission and dynamic light scattering (DLS). The molecular weight of the polymer studied was 9400 g/mol with a polydispersity index of 1.18 and each repeat unit of the polymer had four ethylene glycol monomer segments. The polymer was water soluble due to the hydrophilicity of the OEG side chains and these solutions showed lower critical solution temperature (LCST) depending on the concentration of the polymer. Measurements of solution behavior were made as a function of temperature in the range of 25-55 C for three polymer concentrations (0.1 wt%, 0.3 wt%, and 1.8 wt%). Neutron transmission measurements were used to monitor the amount of polymer which precipitated or remained in solution above the cloud point temperature (T{sub CP}). DLS revealed the presence of large clusters in all solutions both below and above T{sub CP} while SANS provided information on the structure and interactions between individual chains. It was found that in the homogeneous region below T{sub CP} the shape of individual polymers in solution was close to ellipsoidal with the dimensions R{sub a} = 37 Angstroms and R{sub b} = 14 Angstroms and was virtually independent of temperature. The SANS data taken for the most concentrated solution studied (1.8 wt%) were fit to the ellipsoidal model with attractive interactions which were approximated by the Ornstein-Zernike function with a temperature-dependent correlation length in the range of 24-49 Angstroms. The collapse of individual polymers to spherical globules with the radius of 15 Angstroms above TCP was observed.

  16. Conformation of ionizable poly Para phenylene ethynylene in dilute solutions

    SciTech Connect

    Wijesinghe, Sidath; Maskey, Sabina; Perahia, Dvora; Grest, Gary S.

    2015-11-03

    The conformation of dinonyl poly para phenylene ethynylenes (PPEs) with carboxylate side chains, equilibrated in solvents of different quality is studied using molecular dynamics simulations. PPEs are of interest because of their tunable electro-optical properties, chemical diversity, and functionality which are essential in wide range of applications. The polymer conformation determines the conjugation length and their assembly mode and affects electro-optical properties which are critical in their current and potential uses. The current study investigates the effect of carboxylate fraction on PPEs side chains on the conformation of chains in the dilute limit, in solvents of different quality. The dinonyl PPE chains are modeled atomistically, where the solvents are modeled both implicitly and explicitly. Dinonyl PPEs maintained a stretched out conformation up to a carboxylate fraction f of 0.7 in all solvents studied. The nonyl side chains are extended and oriented away from the PPE backbone in toluene and in implicit good solvent whereas in water and implicit poor solvent, the nonyl side chains are collapsed towards the PPE backbone. Thus, rotation around the aromatic ring is fast and no long range correlations are seen within the backbone.

  17. Growth mechanism of a gas clathrate hydrate from a dilute aqueous gas solution: a molecular dynamics simulation of a three-phase system.

    PubMed

    Nada, Hiroki

    2006-08-24

    A molecular dynamics simulation of a three-phase system including a gas clathrate, liquid water, and a gas was carried out at 298 K and high pressure in order to investigate the growth mechanism of the clathrate from a dilute aqueous gas solution. The simulation indicated that the clathrate grew on interfaces between the clathrate and the liquid water, after transfer of the gas molecules from the gas phase to the interfaces. The results suggest a two-step process for growth: first, gas molecules are arranged at cage sites, and second, H(2)O molecules are ordered near the gas molecules. The results also suggest that only the H(2)O molecules, which are surrounded or sandwiched by the gas molecules, form the stable polygons that constitute the cages of the clathrate. In addition, the growth of the clathrate from a concentrated aqueous gas solution was also simulated, and the results suggested a growth mechanism in which many H(2)O and gas molecules correctively form the structure of the clathrate. The clathrate grown from the concentrated solution contained some empty cages, whereas the formation of empty cages was not observed during the growth from the dilute solution. The results obtained by both simulations are compared with the results of an experimental study, and the growth mechanism of the clathrate in a real system is discussed.

  18. Geophysical methods to support correct water sampling locations for salt dilution gauging

    NASA Astrophysics Data System (ADS)

    Comina, C.; Lasagna, M.; De Luca, D. A.; Sambuelli, L.

    2014-08-01

    To improve water management design, particularly in irrigation areas, it is important to evaluate the baseline state of the water resources, including canal discharge. Salt dilution gauging is a traditional and well-documented technique in this respect. The complete mixing of salt used for dilution gauging is required; this condition is difficult to test or verify and, if not fulfilled, is the largest source of uncertainty in the discharge calculation. In this paper, a geophysical technique (FERT, fast electrical resistivity tomography) is proposed for imaging the distribution of the salt plume used for dilution gauging at every point along a sampling cross section. With this imaging, complete mixing can be verified. If the mixing is not complete, the image created by FERT can also provide a possible guidance for selecting water-sampling locations in the sampling cross section. A water multi-sampling system prototype aimed to potentially take into account concentration variability is also proposed and tested. The results reported in the paper show that FERT provides a three-dimensional image of the dissolved salt plume and that this can potentially help in the selection of water sampling points.

  19. The interaction of aluminum with silicic acid in dilute solution and its biological relevance

    SciTech Connect

    Chappell, J.S.; Birchall, J.D. )

    1988-09-01

    The affinity of silicic acid, Si(OH){sub 4}, for aluminum is a unique one in chemistry, owing to ionic size, charge, and coordination geometry of the species involved. The chemistry of aluminosilicates generally has been concerned with the solid state (minerals such as clays, feldspars and zeolites), and relatively little attention has been given to the species which exist in solution since aluminosilicates are highly insoluble near neutral pH. However, under dilute conditions the kinetics of colloid formation can be quite slow and the soluble precursors to a solid phase may be reasonably metastable. When equilibrium is approached, the solubility levels are typically 0.05-0.28 {mu}mol/L Al and 18-210 {mu}mol/L Si. These soluble species are usually regarded as simple hydroxyaluminum ions and silicic acid, although it remains arguable as to whether these species may be associated with each other. The formation of a stable soluble specie would allow for molecular aluminosilicates to exist at below saturation levels. So at concentrations above saturation stable aluminosilicates do form (as a part of an insoluble phase), and they may possibly exist at below saturation (as a stable soluble specie). This interaction is then relevant to biology, where human plasma levels (0.06-0.54 {mu}mol/L Al, 14-39 {mu}mol/L Si) (6,7) fall among saturation values. There is a growing concern over the toxic effects of aluminum, but its chemistry with silicic acid has not been addressed. This chemistry is the topic of this study.

  20. Examples of Savannah River water dilution between the Savannah River Plant and the Beaufort-Jasper and Port Wentworth water-treatment plants

    SciTech Connect

    Hayes, D.W.

    1983-01-12

    A substantial dilution of the river water occurs between the Savannah River Plant (SRP) and the two treatment plants. This dilution results from inflow of surface and groundwater and from direct rainfall. The amount of dilution was estimated to be approximately 20% and 54% down to the Port Wentworth and Beaufort-Jasper plants, respectively.

  1. Interpolymer complex between hydroxypropyl cellulose and maleic acid-styrene copolymer: phase behavior of semi-dilute solutions.

    PubMed

    Bumbu, Gina-Gabriela; Eckelt, John; Wolf, Bernhard A; Vasile, Cornelia

    2005-10-20

    The phase behavior of a water/hydroxypropyl cellulose/maleic acid-styrene copolymer (H2O/HPC/MAc-S) system was investigated in the semi-dilute range by turbidimetry, rheology, and optical microscopy. The two polymers under investigation form interpolymer complexes via hydrogen bonding. In the case of a total polymer concentration of cpol = 5 mg . mL(-1) a second phase segregates upon heating the homogeneous ternary system. By applying a constant shear rate (gamma = 50 s(-1)) the phase separation temperature of the system is 10-15 degrees C lower than for an unsheared one. For cpol = 10 mg . mL(-1) phase separation has already occurred at room temperature when the two binary polymer solutions are mixed. The distribution of the partners among the coexisting phases was examined by FT-IR spectroscopy. The stoichiometry of the interpolymeric complex (IPC) was estimated to be HPC/MAc-S = 40:60 (w/w) independent of cpol.

  2. Oligonucleotides as probes for studying polymerization reactions in dilute aqueous solution

    NASA Technical Reports Server (NTRS)

    Kolb, V.; Orgel, L. E.; Miller, S. L. (Principal Investigator)

    1994-01-01

    We have prepared a [32P]-labled oligonucleotide probe carrying a free primary amine at its 3'-terminus. This probe is used to initiate polymerization of aziridine (ethyleneimine) in aqueous solution. The nature of the oligomeric products and the kinetics of their formation are then monitored by gel electrophoresis. Our results are generally consistent with those obtained using conventional techniques. We have also investigated the effect of polyanionic templates on the rate of oligomerization of aziridine. We find that water-soluble polyanions generally accelerate the polymerization. The sodium salt of polymethacrylic acid is the most effective of the templates that we studied. The methods introduced in this paper should be applicable to a variety of polymerization reactions in aqueous solution. They should greatly simplify the screening of potentially prebiotic polymerization reactions.

  3. Removal of cadmium from dilute solutions by hydroxyapatite: I. Sorption studies

    SciTech Connect

    Mandjiny, S.; Zouboulis, A.I.; Matis, K.A.

    1995-09-01

    The removal of toxic metals (such as cadmium) was investigated by using hydroxyapatite, an effective inorganic sorbent, at the ultrafine particle size range. In bench-scale experiments performed batchwise, the influence of the main sorption parameters were examined (i.e., solution pH, sorbent and cadmium concentrations, and temperature) and comparison was attempted between demineralized and tap water. Typical adsorption isotherms of the Langmuir type were calculated; {zeta}-potential measurements of the hydroxyapatite particles and the release of calcium (during the process) were also examined and related to possible mechanisms occurring during the cadmium removal process.

  4. Determination of the viscosity number of thermoplastics in dilute solution; polyamides (PA)

    NASA Technical Reports Server (NTRS)

    1985-01-01

    This West German Standard presents a test used to determine the viscosity number of polyamides and copolyamides which are easily diluted in sulfuric acid, and for other polyamides which are less easily diluted in sulfuric acid, and which are diluted in m-cresol. As formic acid is often used in industry instead of sulfuric acid, this solvent is also presented as an alternative, however, sulfuric acid is preferred because of the thermodynamic solubility characteristics of the polyamides and the handling safety. In addition, it is shown which solvent should be used for each polyamide. Finally, determinations concerning the preparation of the samples are presented. Using the viscosity number, a determination of the molar mass of the polyamides is possible.

  5. Hot water and dilute acid pretreatment of high and low specific gravity Populus deltoides clones.

    PubMed

    Martin, Elizabeth M; Bunnell, Kris A; Lau, Ching-Shuan; Pelkki, Matthew H; Patterson, David W; Clausen, Edgar C; Smith, James A; Carrier, Danielle Julie

    2011-02-01

    Populus sp. are hardwood feedstocks that grow in forest management areas that are logged for softwoods; however, they are also being considered as an energy-destined feedstock. The objective of this work was to determine the effect of xylose yield from dilute acid and hot water pretreatments performed in unstirred batch stainless steel reactors at temperatures ranging from 140 to 200°C. Populus deltoides clones S13C20 and S7C15 used in this study originated from Eastern Texas and were cultivated for 14 years in Pine Tree, AR. P. deltoides clones S13C20 and S7C15 had specific gravities of 0.48 and 0.40, respectively. Bark and wood were examined separately. As expected, hot water pretreatments, in the tested temperature range, resulted in very little direct xylose recovery. However, the 140°C dilute acid pretreatment of the lower specific gravity clone, S7C15, wood yielded the highest average xylose recovery of 56%. This condition also yielded the highest concentration of furfural, 9 mg/g sample, which can be inhibitory to the fermentation step. The highest xylose recovery from bark samples, 31%, was obtained with clone S7C15, using the 160°C dilute acid pretreatment for 60 min.

  6. Calculation of the transport and relaxation properties of dilute water vapor

    NASA Astrophysics Data System (ADS)

    Hellmann, Robert; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa

    2009-07-01

    Transport properties of dilute water vapor have been calculated in the rigid-rotor approximation using four different potential energy hypersurfaces and the classical-trajectory method. Results are reported for shear viscosity, self-diffusion, thermal conductivity, and volume viscosity in the dilute-gas limit for the temperature range of 250-2500 K. Of these four surfaces the CC-pol surface of Bukowski et al. [J. Chem. Phys. 128, 094314 (2008)] is in best accord with the available measurements. Very good agreement is found with the most accurate results for viscosity in the whole temperature range of the experiments. For thermal conductivity the deviations of the calculated values from the experimental data increase systematically with increasing temperature to around 5% at 1100 K. For both self-diffusion and volume viscosity, the much more limited number of available measurements are generally consistent with the calculated values, apart from the lower temperature isotopically labeled diffusion measurements.

  7. Chain length dependent excited-state decay processes of diluted PF2/6 solutions.

    PubMed

    Pina, João; Seixas de Melo, J Sérgio; Koenen, Niels; Scherf, Ulli

    2013-06-20

    The excited-state dynamics of a series of four poly[2,7-(9,9-bis(2-ethylhexyl)fluorene] fractions, PF2/6, with different chain length (degrees of polymerization DP: 5, 10, 39, and 205) was investigated in dilute solutions by steady-state and time-resolved fluorescence techniques. Two decay components are extracted from time-resolved fluorescence experiments in the picosecond time domain: a chain length dependent, fast decay time (τ(2)) for shorter emission wavelengths (ranging from 30 to 41 ps), which is associated with a rising component at longer wavelengths, and a longer decay time, τ(1) (ranging from 387 to 452 ps). The system was investigated with kinetic formalisms involving (i) a two-state system (A and B) involving conformational relaxation of the initially excited PF2/6 segment (A) under formation of a more planar (B) relaxed state and (ii) a time-dependent red shift of the emission spectrum using the Stokes shift correlation function (SSCF). In the case of (i), the kinetic scheme was solved considering the simultaneous excitation of A and B or only of A, and the rate constants for formation [k′(CR) or k′(CR)(α)], dissociation (k(–CR)), and deactivation (k(B)(*)) were obtained together with the fraction of species A and B present in the ground state. The use of the SSCF in (ii) was found to be more adequate leading to a decay law with a 3.4 ps component (associated with the slow part of the solvation dynamics process) and a longer decay (43.3 ps) associated with the conformational/torsional relaxation process with a rate constant k(CR). This longer component of the SSCF was found to be identical to the short-living decay (τ(2)) component of the biexponential decays, displaying an Arrhenius-type behavior with activation energy values in the range 5.8–8.9 kJ mol(–1) in toluene and 6.5–10.7 kJ mol(–1) in decalin. From the dependence of the fast decay component (k(CR) ≡ 1/τ(2)) on solvent viscosity and temperature, the activation energy

  8. Commercial double-indicator-dilution densitometer using heavy water: Evaluation in oleic-acid pulmonary edema

    SciTech Connect

    Leksell, L.G.; Schreiner, M.S.; Sylvestro, A.; Neufeld, G.R. )

    1990-04-01

    We evaluated a commercially available, double-indicator-dilution densitometric system for the estimation of pulmonary extravascular water volume in oleic acid-induced pulmonary edema. Indocyanine green and heavy water were used as the nondiffusible and diffusible tracers, respectively. Pulmonary extravascular water volume, measured with this system, was 67% of the gravimetric value (r = 0.91), which was consistent with values obtained from the radioisotope methods. The measured volume was not influenced by changes in cardiac index over a range of 1 to 4 L.min.m2. This system is less invasive than the thermal-dye technique and has potential for repeated clinical measurements of pulmonary extravascular lung water and cardiac output.

  9. Synthesis of mesoporous silica helical fibers using a catanionic-neutral ternary surfactant in a highly dilute silica solution: biomimetic silicification.

    PubMed

    Lin, Giung-Ling; Tsai, Yi-Hua; Lin, Hong-Ping; Tang, Chih-Yuan; Lin, Ching-Yen

    2007-04-10

    Mesoporous silica helical fibers in many different shapes have been synthesized in a highly dilute silicate solution at pH approximately 2.0 by using CnTMAB-SDS-P123 (n = 14-18) ternary surfactant as a template. The mesoporous silica helical fibers possess a well-ordered hexagonal mesostructure, high surface area, and large pore volume. Thus, the microtome sections of the helical fibers demonstrate a concentric mesotructure or two hemiconcentric mesostructures. In addition to triblock copolymer, adding the proper amount of 1-butanol or pentanol can promote the yield of the helical fibers as well. The yield of the surfactant-templated helical fibers is also dependent on the water content, reaction temperature, and pH value of the solution. The mesoporous silica helical fiber can be used as a solid template to prepare mesoporous carbon helical fibers via impregnation of phenol-formaldehyde, pyrolysis, and silica removal.

  10. Monte Carlo Simulations of the Dissolution of Borosilicate and Aluminoborosilicate Glasses in Dilute Aqueous Solutions

    SciTech Connect

    Kerisit, Sebastien N.; Pierce, Eric M.

    2011-09-15

    The aim of this study was to provide atomic-level insights into the dissolution behavior of borosilicate and aluminoborosilicate glasses to complement and help interpret previous experimental work on the NeB glass series studied by Pierce et al. [Pierce E. M., Reed L. R., Shaw W. J., McGrail B. P., Icenhower J. P., Windisch C. F., Cordova E. A. and Broady J. (2010) Experimental determination of the effect of the ratio of B/Al on glass dissolution along the nepheline (NaAlSiO4) - Malinkoite (NaBSiO4) join. Geochim. Cosmochim. Acta 74, 2634-2654]. The composition of these glasses was 50 mol% SiO2 - 25 mol% Na2O - (25-x) mol% Al2O3 - x mol% B2O3, with x varying from 0 to 20 mol%. In the first part of this work, the different structural features of these glasses (e.g., presence of non-bridging oxygens, partition of boron between trigonal and tetrahedral bonding environments, and formation of boroxol rings), identified in the study of Pierce et al., were implemented in the Monte Carlo program. Their effects on the dissolution of borosilicate and aluminosilicate glasses were then evaluated individually and led to the following conclusions. (1) The dependence of the dissolution rate on the amount of non-bridging oxygens was found to be linear at all Si/B ratios and the accelerating effect of non-bridging oxygens was shown to increase with increasing Si/B ratio. (2) The formation of boroxol rings and of clusters of boroxol rings resulted in an increase of the dissolution rate at all Si/B ratios and, again, the extent of the rate increase was strongly dependent on the Si/B ratio. (3) For aluminosilicate glasses, the implementation of the aluminum avoidance rule was found to increase the rate of dissolution relative to that obtained for a random distribution. In the second part of this work, Monte Carlo simulations were performed to model the dissolution of the NeB glasses in dilute conditions. One of the conclusions that emerged from the study of Pierce et al. was that

  11. Water-dilutable microemulsions for transepithelial ocular delivery of riboflavin phosphate.

    PubMed

    Lidich, Nina; Wachtel, Ellen J; Aserin, Abraham; Garti, Nissim

    2016-02-01

    Riboflavin phosphate (RFP) is an essential compound in the treatment of keratoconus - a degenerative, non-inflammatory disease of the cornea. Currently, the quantitative and efficient transport of riboflavin to the cornea is possible after mechanical removal of the epithelium. To avoid surgical intervention, it is therefore important to develop a method for quantitatively transporting riboflavin across the intact epithelium. In the present study, an RFP-loaded microemulsion was prepared, which could potentially function as an ocular drug delivery system crossing the eye epithelium. The specially designed water-dilutable microemulsion was based on a mixture of nonionic surfactants. Propylene glycol and glycerol acted as cosurfactant and cosolvent assisting in the solubilization of the RFP. The glycerol-rich water-free concentrate consisted of direct micelles for which glycerol served as the hydrophilic phase. In formulations with up to 40wt% water, the hydrophilic surfactant headgroups and glycerol strongly bind water molecules (DSC and SD-NMR). Above 60wt% water, globular, O/W nanodroplets, ∼14nm in diameter, are formed (SAXS, cryo-TEM, and SD-NMR). The structure of microemulsions loaded with 0.14-4.25wt% RFP (0.29-8.89mmol per 100g formulation) is not significantly influenced by the presence of the RFP. However, in the microemulsions containing 10-80wt% water, the mobility of RFP in the microemulsion is constrained by strong interactions with the surfactants and cosurfactant, and therefore free transport of the molecule can be achieved only upon higher (>80wt%) water dilutions. PMID:26614391

  12. Recovery of propylene glycol from dilute aqueous solutions by reversible chemical complexation with organoboronates

    SciTech Connect

    Broekhuis, R.R.; Lynn, S.; King, C.J.

    1995-05-01

    Extractants consisting of an ion-pair of Aliquat 336 with phenylboronate or 3-nitrophenylboronate were prepared in various diluents (2-ethylhexanol, toluene, o-xylene or diisobutylketone). In batch experiments propyleneglycol (1,2-PD) was effectively extracted even at low concentrations. Heterogeneous complexation constants {beta}{sub 11} calculated at 25 C were 45-120 (mol/1){sup {minus}1} in 2-ethylhexanol, 34.8 (mol/l){sup {minus}1} in toluene, 37.6 (mol/l){sup {minus}1} in o-xylene and 14.4 (mol/l){sup {minus}1} in diisobutylketone. In 2-ethythexanol, there was no significant effect of extractant concentration on the complexation constant. Equilibrium water concentration in the extractants was 8-12 wt %, decreasing with 1,2-PD uptake. Nearly all extractant/diluent systems exhibited overloading (more than stoichiometric uptake of 1,2-PD). Evidence for aggregation of the ion-pair extractant in organic phase was found from water solubilization studies (molar solubilization ratios up to 10) and {sup 1}H NMR spectroscopy studies. Solubilization of 1,2-PD within hydrophilic aggregate interiors may explain the observed overloading. The complexation constant decreased with increasing temperature, but not enough to make back extraction after a temperature change attractive. Back extraction may be achieved after acidification with carbon dioxide to convert the organoboronate anion to the corresponding organoboronic acid. Up to 80% of the extracted 1,2-PD was backextracted in a batch extraction using C0{sub 2}. The extractant could then be regenerated by stripping carbon dioxide from solution at temperatures exceeding 110 C. However, at these temperatures the extractant appears to undergo a transformation in which color changes and extraction capacity is reduced to about 60% of original value.

  13. HEAT OF DILUTION CALCULATION FOR 19 MOLAR SODIUM HYDROXIDE WITH WATER FOR USE IN 241-S-112

    SciTech Connect

    BARTON, W.B.

    2007-02-20

    High concentration caustic solutions are known to cause stress corrosion cracking in carbon steel at elevated temperature. This calculation establishes the conditions where heat of dilution will not cause the solution temperature--concentration to exceed the boundary for stress corrosion cracking as established by NACE International.

  14. Self-diffusion coefficients of the trivalent f-element ion series in dilute and moderately dilute aqueous solutions: A comparative study between europium, gadolinium, terbium and berkelium

    NASA Astrophysics Data System (ADS)

    Rafik, Besbes; Noureddine, Ouerfelli; Abderabbou, Abdelmanef; Habib, Latrous

    2010-03-01

    We have continued the studies on the trivalent ions of the 4f and 5f elements. In this paper, we compare the transport properties (self-diffusion coefficient) of the trivalent aquo ions over two ranges of concentrations (0 — 2×10-3M) and (2×10-3 — 1.5M). Self-diffusion coefficients, D, of the trivalent f-element aquo ion series have been determined in aqueous background electrolytes of Gd(NO3)3 and Nd(ClO4)3, at pH=2.5 (HNO3, HClO4) and at 25°C using the open-end capillary method (O.E.C.M.). This method measures the transportation time of ions across a fixed distance. In this paper, we complete a measurement of self-diffusion coefficient for terbium. We optimized the pH to avoid hydrolysis, ion-pairing and complexation of the trivalent 4f and 5f ions. The variation of D versus √C is not linear for dilute solutions (0 — 2×10-3M) and quasi-linear in moderate concentrations (C<=1.5 M). Similar behavior was observed for Tb, as compared with those for Bk, Eu and Gd. We complete the comparison variation of D/D° versus √C for all studied 4f and 5f elements from concentration 0 to 1.5M and we obtained the same variation with √C for all studied elements. All 4f and 5f elements studied follow the Nernst-Hartley expression.

  15. The Solidification Velocity of Undercooled Nickel and Titanium Alloys with Dilute Solute

    NASA Technical Reports Server (NTRS)

    Algoso, Paul R.; Altgilbers, A. S.; Hofmeister, William H.; Bayuzick, Robert J.

    2003-01-01

    The study of solidification velocity is important for two reasons. First, understanding the manner in which the degree of undercooling of the liquid and solidification velocity affect the microstructure of the solid is fundamental. Second, there is disagreement between theoretical predictions of the relationship between undercooling and solidification velocity and experimental results. Thus, the objective of this research is to accurately and systematically quantify the solidification velocity as a function of undercooling for dilute nickel-and titanium-based alloys. The alloys chosen for study cover a wide range of equilibrium partition coefficients, and the results are compared to current theory.

  16. Scaling of dynamics in 2d semi-dilute polymer solutions

    NASA Astrophysics Data System (ADS)

    Cicuta, P.; Hopkinson, I.

    2004-10-01

    We consider the dynamics of thermal concentration fluctuations in polymer Langmuir monolayers, probed with surface light scattering. We present data on the proteins β-lactoglobulin and β-casein and on the synthetic polymers Poly(vinyl acetate) and Poly(4-hydroxystyrene). We show that for all these systems, in the semi-dilute concentration regime, there is a power law dependency of both the elastic and viscous components of the dilational modulus on the concentration. We find that for all the systems considered, the viscosity scales with a power that is double that of the elasticity. A simple explanation for this universal dynamical behavior in semidilute polymer monolayers is suggested.

  17. Frequency of OH in solutions of n-butanol in carbon tetrachloride: effect of dilution

    NASA Astrophysics Data System (ADS)

    Srivastava, P. K.; Rai, D. K.; Rai, S. B.

    2000-06-01

    It is noted that the 1←0 transition for νOH shows a blue shift as the relative concentration of n-butanol in a CCl 4- n-butanol is reduced. The magnitude of the shift decreases for the 2←0 transition and there is almost no shift for the 3←0 transition. These observations are consistent with the observed red shift [Y. Mizugai, F. Takimoto, M. Katayama, Chem. Phys. Lett. 76 (1980) 615] on dilution for the 5←0 transition in n-butanol. The observations have been interpreted on the basis of formation of O-H. . . . Cl hydrogen bond.

  18. ``Over the horizon`` SANS: Measurements on near-surface Poiseuille shear-induced ordering of dilute solutions of threadlike micelles

    SciTech Connect

    Hamilton, W.A.; Butler, P.D.; Hayter, J.B.; Magid, L.J.; Kreke, P.J.

    1995-06-24

    Although the behavior of a fluid under shear near a surface can be expected to be critically important to its drag and lubrication properties, most shear measurements to date have been of the bulk. This paper outlines the use of a specially developed Poiseuille shear cell at grazing incidence to measure the small-angle neutron scattering (SANS) signal from the first few tens of microns in the interfacial region. The authors illustrate the technique with measurements made on the near-surface ordering in flow past a quartz surface of dilute surfactant solutions comprising highly extended self-assembling ``threadlike`` micelles.

  19. Self-association of caffeine in aqueous solution. Study of dilute solutions by normal and second derivative UV absorption spectroscopy.

    NASA Astrophysics Data System (ADS)

    Iza, N.; Gil, M.; Montero, J. L.; Morcillo, J.

    1988-05-01

    The concentration dependence of the spectral parameters of caffeine bands at ˜205 and 273 nm has been studied in aqueous solution by normal and second derivative spectroscopy. The concentration range was 5 x 10 -6 - 5 x 10 -3 M and thirty-five different concentrations were used. Discontinuities in parameter variation of these two bands at ˜7.5 x 10 -5, ˜2 x 10 -4, and ˜1 x 10 -3M were observed as concentration was increased. These "limiting" concentrations define three quite differenciated hyper- or hipochromic effects: the first one can be explained as caffeine-water molecule interaction and the second and third as dimer and (dimer + polymer) stacking, respectively. Apparent self-association constants using the isodesmic model have been obtained K= 160 M -1 (for the second hypochromic effect) and K= 13.6 M -1 (for the third hypochromic effect), for the 273 nm band. It is noteworthy that the three "limiting" concentrations coincide with changes in DNA-caffeine interaction modes (H. Lang , 1976) and biological activity (I.B. Syed , 1976).

  20. An isotope-dilution standard GC/MS/MS method for steroid hormones in water

    USGS Publications Warehouse

    Foreman, William T.; Gray, James L.; ReVello, Rhiannon C.; Lindley, Chris E.; Losche, Scott A.

    2013-01-01

    An isotope-dilution quantification method was developed for 20 natural and synthetic steroid hormones and additional compounds in filtered and unfiltered water. Deuterium- or carbon-13-labeled isotope-dilution standards (IDSs) are added to the water sample, which is passed through an octadecylsilyl solid-phase extraction (SPE) disk. Following extract cleanup using Florisil SPE, method compounds are converted to trimethylsilyl derivatives and analyzed by gas chromatography with tandem mass spectrometry. Validation matrices included reagent water, wastewater-affected surface water, and primary (no biological treatment) and secondary wastewater effluent. Overall method recovery for all analytes in these matrices averaged 100%; with overall relative standard deviation of 28%. Mean recoveries of the 20 individual analytes for spiked reagent-water samples prepared along with field samples analyzed in 2009–2010 ranged from 84–104%, with relative standard deviations of 6–36%. Detection levels estimated using ASTM International’s D6091–07 procedure range from 0.4 to 4 ng/L for 17 analytes. Higher censoring levels of 100 ng/L for bisphenol A and 200 ng/L for cholesterol and 3-beta-coprostanol are used to prevent bias and false positives associated with the presence of these analytes in blanks. Absolute method recoveries of the IDSs provide sample-specific performance information and guide data reporting. Careful selection of labeled compounds for use as IDSs is important because both inexact IDS-analyte matches and deuterium label loss affect an IDS’s ability to emulate analyte performance. Six IDS compounds initially tested and applied in this method exhibited deuterium loss and are not used in the final method.

  1. Study of dilution, height, and lateral spread of vertical dense jets in marine shallow water.

    PubMed

    Ahmad, Nadeem; Suzuki, Takayuki

    2016-01-01

    This study provides information for the design of sea outfalls to dispose of brine from desalination plants into shallow lagoons of the sea. The behavior of vertical dense jets was studied experimentally by discharging cold saline water vertically upward into a tank filled with hot freshwater under stagnant ambient conditions. The minimum return point dilution, μmin, was determined using thermocouples, and the maximum height, Z(m), and the lateral spread, R(sp), of the fountains were determined by observing shadowgraph pictures. The flow was turbulent and the densimetric Froude number Fr(0) varied from 9 to 18.8. Three mixing regimes were identified: deep, intermediate, and impinging mixing regimes. In the intermediate mixing regime, μ(min) and Z(m) were analyzed and compared with the results of deep water studies. The μ(min) and Z(m) values of fountains at an intermediate water depth were found to be higher than those of fountains at deep water depths. In the impinging regime, μ(min) decreases rapidly when a fountain starts to continuously impinge on the water surface, showing a noticeable disturbance in the water surface. Therefore, a good rule of thumb is to reduce the flow through multiport diffusers from desalination plants when the noticeable disturbance is observed from the top water surface.

  2. Study of dilution, height, and lateral spread of vertical dense jets in marine shallow water.

    PubMed

    Ahmad, Nadeem; Suzuki, Takayuki

    2016-01-01

    This study provides information for the design of sea outfalls to dispose of brine from desalination plants into shallow lagoons of the sea. The behavior of vertical dense jets was studied experimentally by discharging cold saline water vertically upward into a tank filled with hot freshwater under stagnant ambient conditions. The minimum return point dilution, μmin, was determined using thermocouples, and the maximum height, Z(m), and the lateral spread, R(sp), of the fountains were determined by observing shadowgraph pictures. The flow was turbulent and the densimetric Froude number Fr(0) varied from 9 to 18.8. Three mixing regimes were identified: deep, intermediate, and impinging mixing regimes. In the intermediate mixing regime, μ(min) and Z(m) were analyzed and compared with the results of deep water studies. The μ(min) and Z(m) values of fountains at an intermediate water depth were found to be higher than those of fountains at deep water depths. In the impinging regime, μ(min) decreases rapidly when a fountain starts to continuously impinge on the water surface, showing a noticeable disturbance in the water surface. Therefore, a good rule of thumb is to reduce the flow through multiport diffusers from desalination plants when the noticeable disturbance is observed from the top water surface. PMID:27332845

  3. The impact of graphene oxide particles on viscosity stabilization for diluted polymer solutions using in enhanced oil recovery at HTHP offshore reservoirs

    NASA Astrophysics Data System (ADS)

    Dung Nguyen, Ba; Kien Ngo, Trung; Bui, Truong Han; Khanh Pham, Duy; Loc Dinh, Xuan; Nguyen, Phuong Tung

    2015-03-01

    Over 60% of the original oil in a place (OOIP) is retained in a reservoir after conventional methods have been exploited. Application of enhanced oil recovery (EOR) technology gives an additional chance to get out possibly about 20% more oil from the reservoir. The use of water-soluble polymers improves the water-oil mobility ratio, therefore, the displacement efficiency increased, and leads to enhanced oil recovery. High-molecular-weight polyacrylamide group is widely and successfully used in EOR. But no commercial polymer composition can be used in conditions of high temperature and hardness brine offshore reservoirs yet. To avoid the time consumption and high expense for selection and synthesis of the appropriate-structural polymer for EOR application, we attempt to find additives to enhance the thermal stability of polymer solutions. In this paper, we report the results of improved viscosity stability of diluted polymer/seawater solutions aged at reservoir conditions for 31days by adding graphite-oxide particles (GOs). In the presence of 300 ppm of GOs, the viscosity stability of 1700 ppm acrylamide-based polymer in sea water solution increases from 92 °C to 135 °C. FESEM pictures show good distribution of GOs in polymer network, which is a result of integration of functional groups in GOs surfaces and hydrophilic polymer chains.

  4. Investigation of CTBT OSI Radionuclide Techniques at the DILUTED WATERS Nuclear Test Site

    SciTech Connect

    Baciak, James E.; Milbrath, Brian D.; Detwiler, Rebecca S.; Kirkham, Randy R.; Keillor, Martin E.; Lepel, Elwood A.; Seifert, Allen; Emer, Dudley; Floyd, Michael

    2012-11-01

    Under the Comprehensive Nuclear-Test-Ban Treaty (CTBT), a verification regime that includes the ability to conduct an On-Site Inspection (OSI) will be established. The Treaty allows for an OSI to include many techniques, including the radionuclide techniques of gamma radiation surveying and spectrometry and environmental sampling and analysis. Such radioactivity detection techniques can provide the “smoking gun” evidence that a nuclear test has occurred through the detection and quantification of indicative recent fission products. An OSI faces restrictions in time and manpower, as dictated by the Treaty; not to mention possible logistics difficulties due to the location and climate of the suspected explosion site. It is thus necessary to have a good understanding of the possible source term an OSI will encounter and the proper techniques that will be necessary for an effective OSI regime. One of the challenges during an OSI is to locate radioactive debris that has escaped an underground nuclear explosion (UNE) and settled on the surface near and downwind of ground zero. To support the understanding and selection of sampling and survey techniques for use in an OSI, we are currently designing an experiment, the Particulate Release Experiment (PRex), to simulate a small-scale vent from an underground nuclear explosion. PRex will occur at the Nevada National Security Site (NNSS). The project is conducted under the National Center for Nuclear Security (NCNS) funded by the National Nuclear Security Agency (NNSA). Prior to the release experiment, scheduled for Spring of 2013, the project scheduled a number of activities at the NNSS to prepare for the release experiment as well as to utilize the nuclear testing past of the NNSS for the development of OSI techniques for CTBT. One such activity—the focus of this report—was a survey and sampling campaign at the site of an old UNE that vented: DILUTED WATERS. Activities at DILUTED WATERS included vehicle-based survey

  5. Modelling absorption and dilution of unconfined releases of hazardous gases by water curtains or monitors

    SciTech Connect

    Fthenakis, V.M.; Blewitt, D.N.; Hague, W.J.

    1995-05-01

    OSHA Process Safety Management guidelines suggest that a facility operator investigate and document a plan for installing systems to detect, contain, or mitigate accidental releases if such systems are not already in place. In addition, proposed EPA 112(r) regulations would require such analysis. This paper illustrates how mathematical modelling can aid such an evaluation and describes some recent enhancements of the HGSPRAY model: (1) Adding algorithms for modeling NH{sub 3} and LNG mitigation; (2) Modeling spraying of releases with fire water monitors encircling the point of release; (3) Combining wind tunnel modeling with mathematical modeling; and (4) Linking HGSPRAY and BEGADAS. Case cases are presented as examples of how HGSPRAY can aid the design of water spray systems for initiation of toxic gases (e.g., BF, NH,) or dilution/dispersion of flammable vapors (e.g., LNG).

  6. Counterion adsorption theory of dilute polyelectrolyte solutions: Apparent molecular weight, second virial coefficient, and intermolecular structure factor

    PubMed Central

    Muthukumar, M.

    2012-01-01

    Polyelectrolyte chains are well known to be strongly correlated even in extremely dilute solutions in the absence of additional strong electrolytes. Such correlations result in severe difficulties in interpreting light scattering measurements in the determination of the molecular weight, radius of gyration, and the second virial coefficient of charged macromolecules at lower ionic strengths from added strong electrolytes. By accounting for charge-regularization of the polyelectrolyte by the counterions, we present a theory of the apparent molecular weight, second virial coefficient, and the intermolecular structure factor in dilute polyelectrolyte solutions in terms of concentrations of the polymer and the added strong electrolyte. The counterion adsorption of the polyelectrolyte chains to differing levels at different concentrations of the strong electrolyte can lead to even an order of magnitude discrepancy in the molecular weight inferred from light scattering measurements. Based on counterion-mediated charge regularization, the second virial coefficient of the polyelectrolyte and the interchain structure factor are derived self-consistently. The effect of the interchain correlations, dominating at lower salt concentrations, on the inference of the radius of gyration and on molecular weight is derived. Conditions for the onset of nonmonotonic scattering wave vector dependence of scattered intensity upon lowering the electrolyte concentration and interpretation of the apparent radius of gyration are derived in terms of the counterion adsorption mechanism. PMID:22830728

  7. Counterion adsorption theory of dilute polyelectrolyte solutions: apparent molecular weight, second virial coefficient, and intermolecular structure factor.

    PubMed

    Muthukumar, M

    2012-07-21

    Polyelectrolyte chains are well known to be strongly correlated even in extremely dilute solutions in the absence of additional strong electrolytes. Such correlations result in severe difficulties in interpreting light scattering measurements in the determination of the molecular weight, radius of gyration, and the second virial coefficient of charged macromolecules at lower ionic strengths from added strong electrolytes. By accounting for charge-regularization of the polyelectrolyte by the counterions, we present a theory of the apparent molecular weight, second virial coefficient, and the intermolecular structure factor in dilute polyelectrolyte solutions in terms of concentrations of the polymer and the added strong electrolyte. The counterion adsorption of the polyelectrolyte chains to differing levels at different concentrations of the strong electrolyte can lead to even an order of magnitude discrepancy in the molecular weight inferred from light scattering measurements. Based on counterion-mediated charge regularization, the second virial coefficient of the polyelectrolyte and the interchain structure factor are derived self-consistently. The effect of the interchain correlations, dominating at lower salt concentrations, on the inference of the radius of gyration and on molecular weight is derived. Conditions for the onset of nonmonotonic scattering wave vector dependence of scattered intensity upon lowering the electrolyte concentration and interpretation of the apparent radius of gyration are derived in terms of the counterion adsorption mechanism.

  8. Effect of water polyamorphism on the molecular vibrations of glycerol in its glassy aqueous solutions

    NASA Astrophysics Data System (ADS)

    Suzuki, Yoshiharu; Mishima, Osamu

    2016-07-01

    A glassy dilute glycerol-water solution undergoes a mutual polyamorphic transition relating to the transition between high- and low-density amorphous ices of solvent water. The polyamorphic transition behavior depends on the glycerol concentration, indicating that the glycerol affects the water polyamorphism. Here, we used the glassy dilute glycerol-water solution of the solute molar fraction of 0.07 and examined the effect of the polyamorphic change in solvent water on the molecular vibrations of glycerol via Raman spectroscopy. It is found that the molecular vibration of glycerol in high-density liquid like solvent water is different from that in the low-density liquid like solvent water and that the change in the molecular vibration of glycerol is synchronized with the polyamorphic transition of solvent water. The dynamical change of the solute molecule relates to the polyamorphic state of solvent water. This result suggests that the polyamorphic fluctuation of water structure emanated from the presumed liquid-liquid critical point plays an important role for the function of aqueous solution under an ambient condition such as the conformational stability of solute, the functional expression of solute, and so on.

  9. Interaction between colloidal particles on an oil-water interface in dilute and dense phases.

    PubMed

    Parolini, Lucia; Law, Adam D; Maestro, Armando; Buzza, D Martin A; Cicuta, Pietro

    2015-05-20

    The interaction between micron-sized charged colloidal particles at polar/non-polar liquid interfaces remains surprisingly poorly understood for a relatively simple physical chemistry system. By measuring the pair correlation function g(r) for different densities of polystyrene particles at the decane-water interface, and using a powerful predictor-corrector inversion scheme, effective pair-interaction potentials can be obtained up to fairly high densities, and these reproduce the experimental g(r) in forward simulations, so are self consistent. While at low densities these potentials agree with published dipole-dipole repulsion, measured by various methods, an apparent density dependence and long range attraction are obtained when the density is higher. This condition is thus explored in an alternative fashion, measuring the local mobility of colloids when confined by their neighbors. This method of extracting interaction potentials gives results that are consistent with dipolar repulsion throughout the concentration range, with the same magnitude as in the dilute limit. We are unable to rule out the density dependence based on the experimental accuracy of our data, but we show that incomplete equilibration of the experimental system, which would be possible despite long waiting times due to the very strong repulsions, is a possible cause of artefacts in the inverted potentials. We conclude that to within the precision of these measurements, the dilute pair potential remains valid at high density in this system.

  10. Dilution space ratio of 2H and 18O of doubly labeled water method in humans.

    PubMed

    Sagayama, Hiroyuki; Yamada, Yosuke; Racine, Natalie M; Shriver, Timothy C; Schoeller, Dale A

    2016-06-01

    Variation of the dilution space ratio (Nd/No) between deuterium ((2)H) and oxygen-18 ((18)O) impacts the calculation of total energy expenditure (TEE) by doubly labeled water (DLW). Our aim was to examine the physiological and methodological sources of variation of Nd/No in humans. We analyzed data from 2,297 humans (0.25-89 yr old). This included the variables Nd/No, total body water, TEE, body mass index (BMI), and percent body fat (%fat). To differentiate between physiologic and methodologic sources of variation, the urine samples from 54 subjects were divided and blinded and analyzed separately, and repeated DLW dosing was performed in an additional 55 participants after 6 mo. Sex, BMI, and %fat did not significantly affect Nd/No, for which the interindividual SD was 0.017. The measurement error from the duplicate urine sample sets was 0.010, and intraindividual SD of Nd/No in repeats experiments was 0.013. An additional SD of 0.008 was contributed by calibration of the DLW dose water. The variation of measured Nd/No in humans was distributed within a small range and measurement error accounted for 68% of this variation. There was no evidence that Nd/No differed with respect to sex, BMI, and age between 1 and 80 yr, and thus use of a constant value is suggested to minimize the effect of stable isotope analysis error on calculation of TEE in the DLW studies in humans. Based on a review of 103 publications, the average dilution space ratio is 1.036 for individuals between 1 and 80 yr of age. PMID:26989221

  11. Separation of compounds with multiple -OH groups from dilute aqueous solutions via complexation with organoboronate

    SciTech Connect

    Chow, Tina Kuo Fung

    1992-05-01

    The complexing extractant agent investigated in this work is 3-nitrophenylboronic acid (NPBA) in its anionic form (NPB). NPBA and Aliquat 336 (quaternary amine) is dissolved in 2-ethyl-l-hexanol, and the extractant is contacted with aq. NaOH. Solutes investigated were 1,2-propanediol, glycerol, fructose, sorbitol and lactic acid. Batch extraction experiments were performed at 25{degree}C. Partition coefficients, distribution ratios and loadings are reported for varying concentrations of solute and NPB. All solutes complexed with NPB{sup {minus}}, with all complexes containing only one NPB{sup {minus}} per complex. The 1:1 complexation constants for the solutes glycerol, fructose and sorbitol follow trends similar to complexation with B(OH){sub 4}{sup {minus}} (aq.), i.e. the complexation constants increase with increasing number of {minus}OH groups available for complexation. Assumption of 1:1 complex is not valid for 1, 2-propanediol, which showed overloading (more than one mole of solute complexed to one mole NPB{sup {minus}}) at higher concentrations. The {minus}OH group on the NPB{sup {minus}} which is left uncomplexed after one solute molecule had bound to the other two {minus}OH groups may be responsible for the overloading. Overloading is also observed in extraction of tactic acid, but through a different mechanism. It was found that TOMA{sup +} can extract lactic acid to an extent comparable to the uptake of lactic acid by NPB{sup {minus}}. The complexation is probably through formation of an acid-base ion pair. Losses of NPBA into the aqueous phase could lead to problems, poor economics in industrial separation processes. One way of overcoming this problem would be to incorporate the NPBA onto a solid support.

  12. Effect of aging on aluminum hydroxide complexes in dilute aqueous solutions

    USGS Publications Warehouse

    Smith, Ross Wilbert; Hem, John David

    1972-01-01

    Aqueous aluminum solutions containing 4?10 -5 mole/liter aluminum and a constant total ionic strength of 10 -2, but with varying ratios of hydroxide to aluminum (OH:Al), were prepared. Progress of these solutions toward equilibrium conditions over aging periods of as much as 2 years was studied by determining the composition and pH of the solutions at various time intervals. The solutions, after mixing, were supersaturated with respect to both crystalline and amorphous forms of aluminum oxides and aluminum hydroxides. The compositions of the solutions were determined by use of a timed colorimetric analytical procedure which allowed the estimation of three separate forms of aluminum that have been designated Al a, Al b, and Al c. Form Al a appeared to be composed of monomeric species such as Al(H20)6+3, Al(OH)(H20)5+2, Al(OH)2(H20)4 +I and Al(OH)4-. Form Al b was polynuclear material containing perhaps 20-400 aluminum atoms per structure. It appeared to be a metastable material. Form Al c was composed of relatively large, microcrystalline, clearly solid AI(OH)3 particles. For each OH :Al ratio, the concentration of Al a remained constant with aging time, Al b decreased, and Al c increased. It appeared that Al b particles were increasing in size and ultimately were converted to Al c particles. After a few weeks' aging, Al c particles had the structure of gibbsite. In all solutions, equilibrium was only very slowly achieved, and the time required depended on the OH:Al ratio and how rapidly the solution was initially prepared (mixing time). Lower ratios caused a slower approach to equilibrium; sometimes equilibrium was not achieved even after several years' aging. The more slowly base was initially added (to obtain the proper OH:Al ratio), the more slowly was equilibrium approached. Ultimate equilibrium values of dissolved aluminum concentration and pH were consistent with known thermodynamic data on monomeric aluminum species. From data determined during the aging

  13. Water Pollution (Causes, Mechanisms, Solution).

    ERIC Educational Resources Information Center

    Strandberg, Carl

    Written for the general public, this book illustrates the causes, status, problem areas, and prediction and control of water pollution. Water pollution is one of the most pressing issues of our time and the author communicates the complexities of this problem to the reader in common language. The purpose of the introductory chapter is to show what…

  14. REUSABLE ADSORBENTS FOR DILUTE SOLUTIONS SEPARATION. 6. BATCH AND CONTINUOUS REACTORS FOR ADSORPTION AND DEGRADATION OF 1,2-DICHLOROBENZENE FROM DILUTE WASTEWATER STREAMS USING TITANIA AS A PHOTOCATALYST. (R828598C753)

    EPA Science Inventory

    Two types of external lamp reactors were investigated for the titania catalyzed photodegradation of 1,2-dichlorobenzene (DCB) from a dilute water stream. The first one was a batch mixed slurry reactor and the second one was a semi-batch reactor with continuous feed recycle wit...

  15. The adsorption stability & inhibition by allyl-thiourea of bulk nanocrystalline ingot iron in dilute HCl solution

    NASA Astrophysics Data System (ADS)

    Shen, C. B.; Wang, S. G.; Yang, H. Y.; Long, K.; Wang, F. H.

    2006-12-01

    The inhibitive effect of thiourea's (TU) alkyl derivative—allyl-thiourea (ATU) on the corrosion behaviors of bulk nanocrystalline and conventional polycrystalline ingot iron (BNII & CPII) was tested. Results indicate that BNII is less prone to get corrosive than its coarse grain counterpart in blank 1 mol L -1 HCl at room temperature. When CPII and BNII were immersed for a very short time in the corrosive solution inhibited by ATU, namely, 5 min, no inductive loop appears at different concentrations. When time became prolonged, for BNII, a Warburg impedance appeared. Inhibited by ATU, the electrodes composed of the samples are polarized anodically during the potentiodynamic polarization tests, the phenomena of desorption happens at the concentration of 100 mg L -1, but the variation between potential Edes is obvious. The inhibition effect of ATU for BNII is very limited by comparison with CPII in dilute HCl.

  16. Theoretical study of the Pb(II)-catechol system in dilute aqueous solution: Complex structure and metal coordination sphere determination

    NASA Astrophysics Data System (ADS)

    Lapouge, Christine; Cornard, Jean-Paul

    2010-04-01

    We investigated the unknown interaction of Pb(II) with catechol ligand in diluted aqueous solution by electronic spectroscopies combined with quantum chemical calculations. The aim of this work is the determination of the complete structure of the complex formed and particularly the metal coordination sphere. Three successive steps have been necessary to reach this goal: (i) the comparison of the experimental electronic absorption spectrum with theoretical spectra calculated from various hypothetical structures, (ii) complexation reaction pathways calculations in vacuum and with taking into account the solvent effects and finally (iii) the fluorescence emission wavelength calculations. All these investigations led to identify a monodentate complex with the monodeprotonated ligand, in which the Pb atom presents a coordination number of five. The formula of the complex is [Pb(Hcat)(HO)4]mono+.

  17. Fracture fabrication of a multi-scale channel device that efficiently captures and linearizes DNA from dilute solutions.

    PubMed

    Kim, Byoung Choul; Weerappuli, Priyan; Thouless, M D; Takayama, Shuichi

    2015-03-01

    This paper describes a simple technique for patterning channels on elastomeric substrates, at two distinct scales of depth, through the use of controlled fracture. Control of channel depth is achieved by the careful use of different layers of PDMS, where the thickness and material properties of each layer, as well as the position of the layers relative to one another, dictate the depth of the channels formed. The system created in this work consists of a single 'deep' channel, whose width can be adjusted between the micron- and the nano-scale by the controlled application or removal of a uniaxial strain, and an array of 'shallow' nano-scale channels oriented perpendicular to the 'deep' channel. The utility of this system is demonstrated through the successful capture and linearization of DNA from a dilute solution by executing a two-step 'concentrate-then-linearize' procedure. When the 'deep' channel is in its open state and a voltage is applied across the channel network, an overlapping electric double layer forms within the 'shallow' channel array. This overlapping electric double layer was used to prevent passage of DNA into the 'shallow' channels when the DNA molecules migrate into the junctional region by electrophoresis. Release of the applied strain then allows the 'deep' channel to return to its closed state, reducing the cross-sectional area of this channel from the micro- to the nano-scale. The resulting hydrodynamic flow and nano-confinement effects then combine to efficiently uncoil and trap the DNA in its linearized form. By adopting this strategy, we were able to overcome the entropic barriers associated with capturing and linearizing DNA derived from a dilute solution.

  18. Utility of check dams in dilution of fluoride concentration in ground water and the resultant analysis of blood serum and urine of villagers, Anantapur District, Andhra Pradesh, India.

    PubMed

    Bhagavan, S V B K; Raghu, V

    2005-02-01

    High levels of fluoride (beyond 1.5 ppm) in ground water as source of drinking water are common in many parts of Andhra Pradesh, India, causing fluorosis. The study carried out in endemic Nalgonda District, Andhra Pradesh, has indicated that the fluoride-rich ground water present in the wells located down stream and close to the surface water bodies is getting diluted by the low-fluoride surface water. Encouraged by this result, check dams were constructed upstream of the identified marginally high fluoride bearing ground water zones in Anantapur District to reduce fluoride levels as an alternate solution for safe drinking water. In this paper, an attempt is made to study the utility and effect of these check dams in dilution of fluoride concentration in drinking water and its resultant impact on the health aspects of certain villagers of Anantapur District through the analysis of their blood serum and urine. Ground water samples from three fluoride-affected villages, blood and urine of males and females from the same villages were collected and analyzed for fluoride using ion selective electrode method. The results indicated that the fluoride levels in blood serum and urine of males in the age group of 5-11 years are found to be the highest. The concentration of fluoride in ground water is directly proportional to the concentration of fluoride in blood serum and urine. The concentration of fluoride in ground water with depth of the aquifer is a function of lithology, amount and duration of rainfall, rate of infiltration, level of ground water exploitation in the area etc. The construction of check dams upstream of the identified marginally high fluoride waters will not only cause additional recharge of ground water but also reduces the fluoride concentration eventually improving the health of the villagers.

  19. Characterization of the corrosion resistance of several alloys to dilute biologically active solutions

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.

    1990-01-01

    Sulfate reducing bacteria and acid producing bacteria/fungi detected in hygiene waters increased the corrosion rate in aluminum alloy. Biologically active media enhanced the formation of pits on metal coupons. Direct observation of gas evolved at the corrosion sample, coupled with scanning electron microscopy (SEM) and energy dispersive x-ray analysis of the corrosion products indicates that the corrosion rate is increased because the presence of bacteria favor the reduction of hydrogen as the cathodic reaction through the reaction of oxygen and water. SEM verifies the presence of microbes in a biofilm on the surface of corroding samples. The bacterial consortia are associated with anodic sites on the metal surface, aggressive pitting occurs adjacent to biofilms. Many pits are associated with triple points and inclusions in the aluminum alloy microstructure. Similar bacterial colonization was found on the stainless steel samples. Fourier transform Infrared Spectroscopy confirmed the presence of carbonyl groups in pitted areas of samples exposed to biologically active waters.

  20. Recovery of acetic acid from dilute aqueous solutions using catalytic dehydrative esterification with ethanol.

    PubMed

    Yagyu, Daisuke; Ohishi, Tetsuo; Igarashi, Takeshi; Okumura, Yoshikuni; Nakajo, Tetsuo; Mori, Yuichiro; Kobayashi, Shū

    2013-03-01

    We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system. PMID:23290939

  1. Laser flash photolysis and integral equation theory to investigate reactions of dilute solutes with oxygen in supercritical fluids

    SciTech Connect

    Roberts, C.B.; Zhang, J.; Chateauneuf, J.E.; Brennecke, J.F.

    1995-06-21

    The absolute reactivity of triplet benzophenone ({sup 3}BP) and benzyl free radical (PhCH{sub 2}) toward molecular oxygen (O{sub 2}) in supercritical CO{sub 2} and CHF{sub 3} has been measured by laser flash photolysis (LFP). The transient reactants may be considered to be infinitely dilute solutes reacting with a gaseous cosolvent in a supercritical fluid mixture. Both reactants were found to undergo kinetically controlled reactivity with O{sub 2} and the measured bimolecular rate constants (k{sub hi}) were found to decrease with a decrease in solvent density at reduced pressures between 1.0 and 2.5. These results are consistent with solute reactivity with a `nonattractive` cosolvent. The results are compared with those previously obtained for the reaction of {sup 3}BP with an `attractive` cosolvent, 1,4-cyclohexadiene, in supercritical CO{sub 2} and CHF{sub 3}, in which enhanced {sup 3}BP reactivity was observed due to preferential cosolvent/solute solvation. Integral equation theory has also been applied to model these ternary systems, and the results indicate how the strengths of local solvation forces can influence kinetically controlled reactions in supercritical fluids. 36 refs., 8 figs., 3 tabs.

  2. Recovery of propylene glycol from dilute aqueous solutions via reversible reaction with aldehydes

    SciTech Connect

    Broekhuis, R.R.; Lynn, S.; King, C.J. |

    1993-12-01

    A means is proposed for separating propylene glycol and other compounds bearing multiple hydroxyl groups by reversible chemical reaction. Glycols react with aldehydes in cyclic acetalization reactions to form substituted dioxolanes. Propylene glycol reacts with formaldehyde and acetaldehyde to form 4-methyl-1,3-dioxolane and 2,4-dimethyl-1,3-dioxolane. The reaction is catalyzed homogeneously by strong mineral acids or heterogeneously by cation exchange resins in the acid form. Separation processes utilizing this reaction would include an acetalization step, several distillative separation steps and finally a hydrolysis step in which the reaction is reversed. Both reaction steps must be forced to completion by removing the reaction product simultaneously. The equilibrium and kinetics of the reaction with formaldehyde were studied experimentally in systems catalyzed by Amberlite IR-120 ion exchange resin. A number of solvents were screened for their ability to extract 2,4-dimethyl-1,3-dioxolane from aqueous solution. Aromatic hydrocarbons exhibited the highest distribution into the organic phase. To achieve an effective separation of propylene glycol from aqueous solution by combined reaction with formaldehyde and distillation, formaldehyde would have to be present in excess and would be difficult and costly to separate from the aqueous solution. In reactive distillation using acetaldehyde as a reactant this is not a problem. A large flow of acetaldehyde would be necessary to recover the propylene glycol sufficiently in a distillative process. In a process combining reaction and extraction into an organic solvent this problem is avoided. Process simulation indicates the energy input of such a process is less than half of the energy required in a triple-effect evaporation process. This benefit is offset by higher capital costs and increased complexity in the reaction/extraction process.

  3. Effect of arsenic on the activity of oxygen dissolved in dilute liquid copper solutions

    NASA Astrophysics Data System (ADS)

    Walqui, H.; Seetharaman, S.; Staffansson, L. I.

    1985-06-01

    The influence of arsenic additions on the activity of oxygen in liquid copper was studied by the solid-electrolyte galvanic cell (-) Pt, W/Cu-O-As ∥ ZrO2-CaO ∥ NiO-Ni/Pt (+) in the temperature range 1373 to 1473 K. The activity coefficient of oxygen in liquid copper was found to be unaffected by the addition of arsenic. The interaction parameter values for group V B elements in the periodic table with respect to oxygen are discussed in the light of the solute interactions in copper.

  4. Oligonucleotides as probes for studying polymerization reactions in dilute aqueous solution: II. Polycondensations

    NASA Technical Reports Server (NTRS)

    Kolb, V.; Orgel, L. E.

    1995-01-01

    We have prepared a [32P]-labeled oligonucleotide probe carrying a ureido (-NH-CO-NH2) function at its 3'-terminus. This labeled oligomer was used to study polycondensations of urea and formaldehyde and of various phenols and formaldehyde in aqueous solution. The formation of formaldehyde copolymers attached to the amido-function of the probe was monitored by gel electrophoresis. Our results are generally in agreement with those obtained using conventional techniques. Our method is suitable for monitoring potentially prebiotic polycondensation reactions involving formaldehyde.

  5. Oligonucleotides as probes for studying polymerization reactions in dilute aqueous solution. 2: Polycondensations

    NASA Technical Reports Server (NTRS)

    Kolb, Vera; Orgel, Leslie E.

    1995-01-01

    We have prepared a (P-32)-labeled oligonucleotide probe carrying a ureido (-NH-CO-NH2) function at its 3'-terminus. This labeled oligomer was used to study polycondensations of urea and formaldehyde and of various phenols and formaldehyde in aqueous solution. The formation of formaldehyde copolymers attached to the amido-function of the probe was monitored by gel electrophoresis. Our results are generally in agreement with those obtained using conventional techniques. Our method is suitable for monitoring potentially prebiotic polycondensation reactions involving formaldehyde.

  6. Thermodynamic characteristics of the heparin-leucine-CaCl2 system in a diluted physiological solution

    NASA Astrophysics Data System (ADS)

    Nikolaeva, L. S.; Belov, G. V.; Rulev, Yu. A.; Semenov, A. N.

    2013-03-01

    Chemical equilibria in aqueous solutions of high-molecular weight heparin (Na4hep) and leucine (HLeu) are calculated through the mathematical modeling of chemical equilibria based on representative experimental pH titration data. In addition, chemical equilibria in the CaCl2-Na4hep-HLeu-H2O-NaCl system in the presence of 0.154M NaCl background electrolyte at a temperature of 37°C in the range of 2.30 ≤ pH ≤ 10.50 and initial concentrations of basic components n × 10-3 M ( n ≤ 4).

  7. Semi-crystalline polymethylene-b-poly(acrylic acid) diblock copolymers: aggregation behavior, confined crystallization and controlled growth of semicrystalline micelles from dilute DMF solution.

    PubMed

    Wang, Hongfang; Wu, Cong; Xia, Guangmei; Ma, Zhi; Mo, Guang; Song, Rui

    2015-03-01

    In this paper, we have systematically investigated the aggregation behavior, confined crystallization and controlled growth of a novel polyolefin analogue-containing block copolymers (BCPs), i.e., polymethylene-b-poly(acrylic acid) diblock copolymers (PM-b-PAA). On cooling from a homogenous DMF solution at 80 °C, PM-b-PAA was found to crystallize and aggregate with well-defined disk-like micelles. The aggregate behavior and in-plane morphology of PM-b-PAA could be easily controlled by modifying the block ratio, solution pH and solvent composition (DMF-water), by manipulating the crystallization of PM block and the stretching degree of solvated PAA corona. Further investigation of the crystalline feature of PM-b-PAA indicated that the crystallization of PM was retarded by tethered amorphous PAA segments. The crystalline micelle could construct a nano-confined environment with PM folding as the core into a thickness of the mono-layered polyethylene. Finally, when cultured in dilute DMF solution at 50 °C, the initial crystalline micelles, being as self-seeds, could follow a living growth mechanism and develop into single crystals, with well-defined lozenge-shaped morphology.

  8. Semi-crystalline polymethylene-b-poly(acrylic acid) diblock copolymers: aggregation behavior, confined crystallization and controlled growth of semicrystalline micelles from dilute DMF solution.

    PubMed

    Wang, Hongfang; Wu, Cong; Xia, Guangmei; Ma, Zhi; Mo, Guang; Song, Rui

    2015-03-01

    In this paper, we have systematically investigated the aggregation behavior, confined crystallization and controlled growth of a novel polyolefin analogue-containing block copolymers (BCPs), i.e., polymethylene-b-poly(acrylic acid) diblock copolymers (PM-b-PAA). On cooling from a homogenous DMF solution at 80 °C, PM-b-PAA was found to crystallize and aggregate with well-defined disk-like micelles. The aggregate behavior and in-plane morphology of PM-b-PAA could be easily controlled by modifying the block ratio, solution pH and solvent composition (DMF-water), by manipulating the crystallization of PM block and the stretching degree of solvated PAA corona. Further investigation of the crystalline feature of PM-b-PAA indicated that the crystallization of PM was retarded by tethered amorphous PAA segments. The crystalline micelle could construct a nano-confined environment with PM folding as the core into a thickness of the mono-layered polyethylene. Finally, when cultured in dilute DMF solution at 50 °C, the initial crystalline micelles, being as self-seeds, could follow a living growth mechanism and develop into single crystals, with well-defined lozenge-shaped morphology. PMID:25608942

  9. Volumetric Properties of Dilute Aqueous Solutions of 1- and 2-propanol to 50 MPa and 373.15 K

    NASA Astrophysics Data System (ADS)

    Seitz, J.; Bahramian, J.; Blackwell, R.; Inaki, T.; York, D.; Schulte, M. D.

    2014-12-01

    The need to accurately model and understand reactions among organic compounds and biomolecules in solution is necessary to develop realistic chemical models for the reactions leading to the emergence of life and metabolic processes of extremophiles under elevated temperature and pressure conditions. Unfortunately, the scarcity of experimentally determined volumetric (and other) properties for important compounds at high temperatures and pressures leads to uncertainty in the calculation of reaction properties. Experimentally determined volumetric properties of aqueous solutions at non-standard conditions provide direct tests of current estimation methods and aid in the refinement of these methods. The goal of our research is to provide a database of experimentally determined volumetric properties. In previous studies, we have examined important organic molecules and biomolecules such as adenosine, coenzyme M and D-ribose. In this study, we investigate the volumetric properties of the structural isomers 1- and 2-propanol. 1-propanol (n-propanol) is a primary alcohol (CH3CH2CH2OH) and 2-propanol (isopropanol) is the simplest example of a secondary alcohol (CH3CHOHCH3). These compounds differ slightly in structure depending on to which carbon atom the hydroxyl group is bonded and will provide a sensitive test of current estimation methods and lead to more accurate predictions of the properties of complex aqueous systems at elevated temperatures and pressures. We obtained the densities of aqueous solutions of the alchohols using an Anton Paar DMA HP vibrating tube densimeter. Pressure was measured (pressure transducer) to an accuracy of ±0.01% and temperature was measured (integrated platinum thermometer) with an accuracy of ±0.05 K. Experimental uncertainty of density measurements is less than ±0.0001 g·cm-3. The partial molar volumes at infinite dilution (V∞) for 1- and 2-propanol were calculated from the measured densities and are shown in the figure at 0

  10. Selective on site separation and detection of molecules in diluted solutions with super-hydrophobic clusters of plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Gentile, Francesco; Coluccio, Maria Laura; Zaccaria, Remo Proietti; Francardi, Marco; Cojoc, Gheorghe; Perozziello, Gerardo; Raimondo, Raffaella; Candeloro, Patrizio; di Fabrizio, Enzo

    2014-06-01

    Super-hydrophobic surfaces are bio-inspired interfaces with a superficial texture that, in its most common evolution, is formed by a periodic lattice of silicon micro-pillars. Similar surfaces reveal superior properties compared to conventional flat surfaces, including very low friction coefficients. In this work, we modified meso-porous silicon micro-pillars to incorporate networks of metal nano-particles into the porous matrix. In doing so, we obtained a multifunctional-hierarchical system in which (i) at a larger micrometric scale, the super-hydrophobic pillars bring the molecules dissolved in an ultralow-concentration droplet to the active sites of the device, (ii) at an intermediate meso-scale, the meso-porous silicon film adsorbs the low molecular weight content of the solution and, (iii) at a smaller nanometric scale, the aggregates of silver nano-particles would measure the target molecules with unprecedented sensitivity. In the results, we demonstrated how this scheme can be utilized to isolate and detect small molecules in a diluted solution in very low abundance ranges. The presented platform, coupled to Raman or other spectroscopy techniques, is a realistic candidate for the protein expression profiling of biological fluids.Super-hydrophobic surfaces are bio-inspired interfaces with a superficial texture that, in its most common evolution, is formed by a periodic lattice of silicon micro-pillars. Similar surfaces reveal superior properties compared to conventional flat surfaces, including very low friction coefficients. In this work, we modified meso-porous silicon micro-pillars to incorporate networks of metal nano-particles into the porous matrix. In doing so, we obtained a multifunctional-hierarchical system in which (i) at a larger micrometric scale, the super-hydrophobic pillars bring the molecules dissolved in an ultralow-concentration droplet to the active sites of the device, (ii) at an intermediate meso-scale, the meso-porous silicon film

  11. The aggregation behavior of native collagen in dilute solution studied by intrinsic fluorescence and external probing

    NASA Astrophysics Data System (ADS)

    Wu, Kun; Liu, Wentao; Li, Guoying

    2013-02-01

    The aggregation behavior of type I collagen in acid solutions with the concentrations covering a range of 0.06-1.50 mg/mL was studied utilizing both of the fluorescence resonance energy transfer (FRET) between the phenylalanine and tyrosine residues and the external probing of 1,8-anilinonaphthalene sulfonate (ANS). FRET at 0.30 mg/mL showed the distance among collagen monomers was within 10 nm without the obvious aggregates formed. The predominance of tyrosine fluorescence in FRET in the range of 0.45-0.75 mg/mL identified the existence of collagen aggregates companied with the formation of hydrophobic microdomains revealed by the change of the fluorescence of ANS. The blue-shift of tyrosine fluorescence from 303 to 293 nm for 0.90-1.50 mg/mL dedicated the formation of high order aggregates. The results from the two-phase diagrams of the intrinsic fluorescence for the guanidine hydrochloride-induced unfolding of collagen confirmed these conclusions. By the two-dimensional correlation analysis for the intrinsic fluorescence of collagen solutions of 0.45, 0.75 and 1.05 mg/mL, the probable characteristic fluorescence peaks for the interactions of proline-aromatic (CH ˜ π) among the collagen molecules were found at 298 and 316 nm.

  12. Dynamic dissolution of halite rock during flow of diluted saline solutions

    NASA Astrophysics Data System (ADS)

    Weisbrod, N.; Alon-Mordish, C.; Konen, E.; Yechieli, Y.

    2012-05-01

    The dynamic dissolution pattern of halite salt rocks taken from coreholes near the Dead Sea was studied in laboratory-scale experiments. When unsaturated solution (with respect to halite) flowed through salt cores, dissolution developed along preferential flow pathways in a channel structure. The channel structure was related to the salt's properties and internal heterogeneities, flow velocity and impact of gravity. Preferential dissolution pathways developed in areas of minimum resistance to flow, such as large-pore networks and cracks. Nevertheless, in many cases no structural heterogeneity was observed along the dissolution channels prior to the experiments. The initial formation of channels took place above a critical flow velocity; below this threshold, dissolution developed as a slowly propagating front. In these cases, salt re-precipitation resulted in clogging and cessation of flow through a few of the salt cores. Solution density was found to be important, as evidenced by the fact that more channels developed upward than downward, due to gravitational fractionation. The development of dissolution channels could have very important implications for the overall permeability of the salt layer in general, and the use of salt formations for industrial waste storage and the development of sinkholes along the Dead Sea shore in particular.

  13. Hausmannite (Mn3O4) conversion to manganite (γ-MnOOH) in dilute oxalate solution

    USGS Publications Warehouse

    Lind, Carol J.

    1988-01-01

    Oxalic acid retards the alteration of Mn3O4 to γ-MnOOH during aging at pH 7.4 ?? 0.2 in well-aerated, abiotic suspensions that contain 4.4 ?? 10-3 M total Mn. In solutions of 1.25 ?? 10-3 M oxalate and greater, about 15% of the initial Mn3O4 altered to ??-MnOOH by day 10, and in solutions of 6.7 ?? 10-4 M oxalate, about 45% altered to ??-MnOOH by day 67. Although precipitation continued through day 365, the degree of conversion remained the same as at day 10 and day 67, respectively. In oxalate-free suspensions, the conversion was about 80% complete by day 67 and 100% by day 109. Oxalate complexed most of the dissolved divalent Mn, lowered the free Mn(II) and MnSO40 concentrations, but increased the total dissolved Mn. Steric hindrance of surface reactions by a suggested manganese oxalate layer on the Mn3O4 surface may explain the blockage of the oxidation cycle.

  14. Electrochemical Behavior of Nano-grained Pure Copper in Dilute Alkaline Solution with Chloride Ion Trace

    NASA Astrophysics Data System (ADS)

    Fattah-Alhosseini, Arash; Imantalab, Omid; Attarzadeh, Farid Reza

    2016-10-01

    Effect of nano-grained structure on the interface behavior of pure copper in 0.01M KOH solution with chloride ion trace is investigated by various electrochemical techniques. Nano-grained structure was achieved by accumulative roll bonding (ARB) technique. Before any electrochemical measurements, microstructure was evaluated by means of optical microscopy and transmission electron microscopy (TEM). TEM observations showed that nano-grains (with an average size of below 100 nm) appeared after eight passes of ARB. Polarization curves revealed that increasing chloride ion concentration leads to a decrease in the corrosion and pitting potentials of both annealed and nano-grained pure copper samples. Electrochemical impedance spectroscopy revealed that chloride ion trace lowers passive film resistance and charge-transfer resistance in both annealed and nano-grained samples. Mott-Schottky analysis showed that the surface films formed on annealed and nano-grained samples in KOH solution with and without NaCl addition are of p-type semiconducting behavior. Moreover, this analysis showed that the acceptor density increases by increasing chloride ion concentration.

  15. Electrochemical Behavior of Nano-grained Pure Copper in Dilute Alkaline Solution with Chloride Ion Trace

    NASA Astrophysics Data System (ADS)

    Fattah-Alhosseini, Arash; Imantalab, Omid; Attarzadeh, Farid Reza

    2016-08-01

    Effect of nano-grained structure on the interface behavior of pure copper in 0.01M KOH solution with chloride ion trace is investigated by various electrochemical techniques. Nano-grained structure was achieved by accumulative roll bonding (ARB) technique. Before any electrochemical measurements, microstructure was evaluated by means of optical microscopy and transmission electron microscopy (TEM). TEM observations showed that nano-grains (with an average size of below 100 nm) appeared after eight passes of ARB. Polarization curves revealed that increasing chloride ion concentration leads to a decrease in the corrosion and pitting potentials of both annealed and nano-grained pure copper samples. Electrochemical impedance spectroscopy revealed that chloride ion trace lowers passive film resistance and charge-transfer resistance in both annealed and nano-grained samples. Mott-Schottky analysis showed that the surface films formed on annealed and nano-grained samples in KOH solution with and without NaCl addition are of p-type semiconducting behavior. Moreover, this analysis showed that the acceptor density increases by increasing chloride ion concentration.

  16. Effects of dilute aqueous NaCl solution on caffeine aggregation

    SciTech Connect

    Sharma, Bhanita; Paul, Sandip

    2013-11-21

    The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

  17. Effects of dilute aqueous NaCl solution on caffeine aggregation

    NASA Astrophysics Data System (ADS)

    Sharma, Bhanita; Paul, Sandip

    2013-11-01

    The effect of salt concentration on association properties of caffeine molecule was investigated by employing molecular dynamics simulations in isothermal-isobaric ensemble of eight caffeine molecules in pure water and three different salt (NaCl) concentrations, at 300 K temperature and 1 atm pressure. The concentration of caffeine was taken almost at the solubility limit. With increasing salt concentration, we observe enhancement of first peak height and appearance of a second peak in the caffeine-caffeine distribution function. Furthermore, our calculated solvent accessible area values and cluster structure analyses suggest formation of higher order caffeine cluster on addition of salt. The calculated hydrogen bond properties reveal that there is a modest decrease in the average number of water-caffeine hydrogen bonds on addition of NaCl salt. Also observed are: (i) decrease in probability of salt contact ion pair as well as decrease in the solvent separated ion pair formation with increasing salt concentration, (ii) a modest second shell collapse in the water structure, and (iii) dehydration of hydrophobic atomic sites of caffeine on addition of NaCl.

  18. Characterization of lignin derived from water-only and dilute acid flowthrough pretreatment of poplar wood at elevated temperatures

    SciTech Connect

    Zhang, Libing; Yan, Lishi; Wang, Zheming; Laskar, Dhrubojyoti D.; Swita, Marie S.; Cort, John R.; Yang, Bin

    2015-12-01

    In this study, flowthrough pretreatment of biomass has high potential to valorize lignin derivatives to high-value products, which is vital to enhance the economy of biorefinery plants. Comprehensive understanding of lignin behaviors and solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of providing flexible platform for lignin utilization. In this study, the effects of flowthrough pretreatment conditions on lignin separation from poplar wood were reported as well as the characteristics of three sub-sets of lignin produced from the pretreatment, including residual lignin in pretreated solid residues (ReL), recovered insoluble lignin in pretreated liquid (RISL), and recovered soluble lignin in pretreatment liquid (RSL). Both the water-only and 0.05% (w/w) sulfuric acid pretreatments were performed at temperatures from 160 to 270°C on poplar wood in a flowthrough reactor system for 2-10 min. Results showed that water-only flowthrough pretreatment primarily removed syringyl (S units). Increased temperature and/or the addition of sulfuric acid enhanced the removal of guaiacyl (G units) compared to water-only pretreatments at lower temperatures, resulting in nearly complete removal of lignin from the biomass. Results also suggested that more RISL was recovered than ReL and RSL in both dilute acid and water-only flowthrough pretreatment at elevated temperatures. NMR spectra of the RISL revealed significant β-O-4 cleavage, α-β deoxygenation to form cinnamyl-like end groups, and slight β-5 repolymerization in both water-only and dilute acid flowthrough pretreatments. In conclusion, elevated temperature and/or dilute acid greatly enhanced lignin removal to almost 100% by improving G unit removal besides S unit removal in flowthrough system. A new lignin chemistry transformation pathway was proposed and revealed the complexity of lignin structural change during

  19. Conformational study of a single molecule of poly para phenylene ethynylenes in dilute solutions.

    PubMed

    Maskey, Sabina; Pierce, Flint; Perahia, Dvora; Grest, Gary S

    2011-06-28

    The conformation of single molecules of dialkyl poly para phenylene ethynylenes (PPEs), electro-active polymers, is studied in solutions using molecular dynamics simulations. The conformation of conjugated polymers affects their electro-optical properties and therefore is critical to their current and potential uses, though only limited theoretical knowledge is available regarding the factors that control their configuration. The present study investigates the affects of molecular parameters including molecular weight of the polymer and chemical structure of the side chains of PPEs in different solvents on the conformation of the polymers. The PPEs are modeled atomistically where the solvents are modeled both implicitly and explicitly. The study finds that PPEs assume extended configuration which is affected by the length of the polymer backbone and the nature and length of substituting side chains. While the polymer remains extended, local dynamics is retained and no long range correlations are observed within the backbone. The results are compared with scattering experiments.

  20. Modelling the interfacial behaviour of dilute light-switching surfactant solutions.

    PubMed

    Herdes, Carmelo; Santiso, Erik E; James, Craig; Eastoe, Julian; Müller, Erich A

    2015-05-01

    The direct molecular modelling of an aqueous surfactant system at concentrations below the critical micelle concentration (pre-cmc) conditions is unviable in terms of the presently available computational power. Here, we present an alternative that combines experimental information with tractable simulations to interrogate the surface tension changes with composition and the structural behaviour of surfactants at the water-air interface. The methodology is based on the expression of the surface tension as a function of the surfactant surface excess, both in the experiments and in the simulations, allowing direct comparisons to be made. As a proof-of-concept a coarse-grained model of a light switching non-ionic surfactant bearing a photosensitive azobenzene group is considered at the air-water interface at 298 K. Coarse-grained molecular dynamic simulations are detailed based on the use of the SAFT force field with parameters tuned specifically for this purpose. An excellent agreement is obtained between the simulation predictions and experimental observations; furthermore, the molecular model allows the rationalization of the macroscopic behaviour in terms of the different conformations of the cis and trans surfactants at the surface.

  1. Water dynamics in divalent and monovalent concentrated salt solutions.

    PubMed

    Giammanco, Chiara H; Wong, Daryl B; Fayer, Michael D

    2012-11-26

    Water hydrogen bond dynamics in concentrated salt solutions are studied using polarization-selective IR pump-probe spectroscopy and 2D IR vibrational echo spectroscopy performed on the OD hydroxyl stretching mode of dilute HOD in H(2)O/salt solutions. The OD stretch is studied to eliminate vibrational excitation transfer, which interferes with the dynamical measurements. Though previous research suggested that only the anion affected dynamics in solution, here it is shown that the cation plays a role as well. From FT-IR spectra of the OD stretch, it is seen that replacing either ion of the salt pair causes a shift in absorption frequency relative to that of the OD stretch absorption in bulk pure water. This shift becomes pronounced with larger, more polarizable anions or smaller, high charge-density cations. The vibrational lifetime of the OD hydroxyl stretch in these solutions is a local property and is primarily dependent on the nature of the anion and whether the OD is hydrogen bonded to the anion or to the oxygen of another water molecule. However, the cation still has a small effect. Time dependent anisotropy measurements show that reorientation dynamics in these concentrated solutions is a highly concerted process. While the lifetime, a local probe, displays an ion-associated and a bulk-like component in concentrated solutions, the orientational relaxation does not have two subensemble dynamics, as demonstrated by the lack of a wavelength dependence. The orientational relaxation of the single ensemble is dependent on the identity of both the cation and anion. The 2D IR vibrational echo experiments measure spectral diffusion that is caused by structural evolution of the system. The vibrational echo measurements yield the frequency-frequency correlation function (FFCF). The results also show that the structural dynamics are dependent on the cation as well as the anion. PMID:23113682

  2. A Novel Low-Power, High-Performance, Zero-Maintenance Closed-Path Trace Gas Eddy Covariance System with No Water Vapor Dilution or Spectroscopic Corrections

    NASA Astrophysics Data System (ADS)

    Sargent, S.; Somers, J. M.

    2015-12-01

    Trace-gas eddy covariance flux measurement can be made with open-path or closed-path analyzers. Traditional closed-path trace-gas analyzers use multipass absorption cells that behave as mixing volumes, requiring high sample flow rates to achieve useful frequency response. The high sample flow rate and the need to keep the multipass cell extremely clean dictates the use of a fine-pore filter that may clog quickly. A large-capacity filter cannot be used because it would degrade the EC system frequency response. The high flow rate also requires a powerful vacuum pump, which will typically consume on the order of 1000 W. The analyzer must measure water vapor for spectroscopic and dilution corrections. Open-path analyzers are available for methane, but not for nitrous oxide. The currently available methane analyzers have low power consumption, but are very large. Their large size degrades frequency response and disturbs the air flow near the sonic anemometer. They require significant maintenance to keep the exposed multipass optical surfaces clean. Water vapor measurements for dilution and spectroscopic corrections require a separate water vapor analyzer. A new closed-path eddy covariance system for measuring nitrous oxide or methane fluxes provides an elegant solution. The analyzer (TGA200A, Campbell Scientific, Inc.) uses a thermoelectrically-cooled interband cascade laser. Its small sample-cell volume and unique sample-cell configuration (200 ml, 1.5 m single pass) provide excellent frequency response with a low-power scroll pump (240 W). A new single-tube Nafion® dryer removes most of the water vapor, and attenuates fluctuations in the residual water vapor. Finally, a vortex intake assembly eliminates the need for an intake filter without adding volume that would degrade system frequency response. Laboratory testing shows the system attenuates the water vapor dilution term by more than 99% and achieves a half-power band width of 3.5 Hz.

  3. Shear Induced Rupturing of Nanoemulsion Droplets in Dilute and Concentrated Surfactant Solutions

    NASA Astrophysics Data System (ADS)

    Graves, S.

    2005-03-01

    We use high-pressure microfluidic injection to rupture silicone oil-in-water droplets repeatedly down to diameters below 100 nm, thereby creating ``nanoemulsions.'' These droplets are stabilized against coalescence by the surfactant sodium dodecyl sulfate (SDS). We systematically increase the SDS concentration, C, from 8 to 1000 mM, and we find a decrease in the droplet radius that follows a power law form:˜C^-α, where α= 1/3, over several decades in C down to an average radius of = 18 nm. The larger droplet radius at small C may be due to reduced coverage of the deformed droplet surfaces by the surfactant, thereby facilitating shear-induced coalescence. Our observed decrease in the droplet radius deviates from the classical prediction that the radius is inversely proportional to the viscosity of the continuous phase.

  4. Selective on site separation and detection of molecules in diluted solutions with super-hydrophobic clusters of plasmonic nanoparticles.

    PubMed

    Gentile, Francesco; Coluccio, Maria Laura; Zaccaria, Remo Proietti; Francardi, Marco; Cojoc, Gheorghe; Perozziello, Gerardo; Raimondo, Raffaella; Candeloro, Patrizio; Di Fabrizio, Enzo

    2014-07-21

    Super-hydrophobic surfaces are bio-inspired interfaces with a superficial texture that, in its most common evolution, is formed by a periodic lattice of silicon micro-pillars. Similar surfaces reveal superior properties compared to conventional flat surfaces, including very low friction coefficients. In this work, we modified meso-porous silicon micro-pillars to incorporate networks of metal nano-particles into the porous matrix. In doing so, we obtained a multifunctional-hierarchical system in which (i) at a larger micrometric scale, the super-hydrophobic pillars bring the molecules dissolved in an ultralow-concentration droplet to the active sites of the device, (ii) at an intermediate meso-scale, the meso-porous silicon film adsorbs the low molecular weight content of the solution and, (iii) at a smaller nanometric scale, the aggregates of silver nano-particles would measure the target molecules with unprecedented sensitivity. In the results, we demonstrated how this scheme can be utilized to isolate and detect small molecules in a diluted solution in very low abundance ranges. The presented platform, coupled to Raman or other spectroscopy techniques, is a realistic candidate for the protein expression profiling of biological fluids.

  5. ``Ordered'' structure in dilute solutions of biopolymers as studied by small-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Matsuoka, Hideki; Ise, Norio; Okubo, Tsuneo; Kunugi, Shigeru; Tomiyama, Hiroshi; Yoshikawa, Yukihiro

    1985-07-01

    Dilute aqueous solutions of bovine serum albumin, lysozyme, chondroitin sulfate, and tRNA were measured by small-angle x-ray scattering. The scattering curves showed a single, broad peak as was observed for synthetic polyelectrolytes, indicating the presence of an ordered distribution of charged solutes. The intermolecular distance evaluated from the peak position (2Dexpt) increased with decreasing polymer concentration and with increasing salt concentration. Except for chondroitin sulfate, 2Dexpt values were nearly equal to the interparticle distance (2D0) calculated based on the assumption of a uniform distribution. The observed relationship between 2Dexpt and 2D0 was in agreement with the proposal that intermacroion attraction is weak for low-charge density particles under discussion. This attraction and repulsive interparticle interaction create a ``secondary'' minimum in the potential curve enabling ordering to take place. For tRNA, the scattering peak became lower with rising temperature. The fact that only a single, broad peak could be observed was rationalized by invoking the concept of distortions of ordering particles such as the paracrystallinity, and the thermal motion and the crystalline size effect. The correlation hole theory based on repulsive interaction is critically discussed, particularly in light of the experimental fact that the peak position of albumin shifts toward wider angles with increasing number of charges.

  6. Molecular simulations of self-assembly processes of amphiphiles in dilute solutions: the challenge for quantitative modelling

    NASA Astrophysics Data System (ADS)

    Jusufi, Arben

    2013-11-01

    We report on two recent developments in molecular simulations of self-assembly processes of amphiphilic solutions. We focus on the determination of micelle formation of ionic surfactants which exhibit the archetype of self-assembling compounds in solution. The first approach is centred on the challenge in predicting micellisation properties through explicit solvent molecular dynamics simulations. Even with a coarse-grained (CG) approach and the use of highly optimised software packages run on graphics processing unit hardware, it remains in many cases computationally infeasible to directly extract the critical micelle concentration (cmc). However, combined with a recently presented theoretical mean-field model this task becomes resolved. An alternative approach to study self-assembly is through implicit solvent modelling of the surfactants. Here we review some latest results and present new ones regarding capabilities of such a modelling approach in determining the cmc, and the aggregate structures in the dilute regime, that is currently not accessible through explicit solvent simulations, neither through atomistic nor through CG approaches. A special focus is put on surfactant concentration effects and surfactant correlations quantified by scattering intensities that are compared to recently published small-angle X-ray scattering data.

  7. UV luminescent organic-capped ZnO quantum dots synthesized by alkoxide hydrolysis with dilute water.

    PubMed

    Omata, Takahisa; Takahashi, Kazuyuki; Hashimoto, Shinichi; Maeda, Yasuhiro; Nose, Katsuhiro; Otsuka-Yao-Matsuo, Shinya; Kanaori, Kenji

    2011-03-15

    A novel synthesis route to organic-capped and colloidal ZnO quantum dots (QDs) has been developed. Specifically, zinc-di-t-butoxide and zinc-di-n-butoxide are hydrolyzed by very dilute water (400-600 mass ppm) in hydrophilic benzylamine and polymerized to ZnO by dehydration and/or a butanol elimination reaction. Growth of the ZnO QDs and exchange of the surface capping ligand from the hydroxyl groups and/or benzylamine to the oleylamine occur by heating the colloidal solution after addition of the oleylamine at 100-180°C. The final ZnO QDs with diameters in the range of 3-7 nm are highly dispersible in various organic solvents. The ZnO QDs exhibit the quantum size effect upon UV emission; it was controlled between 3.39 and 3.54 eV in the present study. The defect-related Vis emission decreased and the UV emission becomes dominant when zinc-di-n-butoxide with a 99.99% zinc purity is used as the starting material. The intensity of the photoluminescence UV emission is 1.5 times higher than that of the Vis emission.

  8. WaterNet: The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Houser, P. R.; Belvedere, D. R.; Pozzi, W. H.; Imam, B.; Schiffer, R.; Lawford, R.; Schlosser, C. A.; Gupta, H.; Welty, C.; Vorosmarty, C.; Matthews, D.

    2007-12-01

    Water is essential to life and directly impacts and constrains society's welfare, progress, and sustainable growth, and is continuously being transformed by climate change, erosion, pollution, and engineering practices. The water cycle is a critical resource for industry, agriculture, natural ecosystems, fisheries, aquaculture, hydroelectric power, recreation, and water supply, and is central to drought, flood, transportation-aviation, and disease hazards. It is therefore a national priority to use advancements in scientific observations and knowledge to develop solutions to the water challenges faced by society. NASA's unique role is to use its view from space to improve water and energy cycle monitoring and prediction. NASA has collected substantial water cycle information and knowledge that must be transitioned to develop solutions for all twelve National Priority Application (NPA) areas. NASA cannot achieve this goal alone -it must establish collaborations and interoperability with existing networks and nodes of research organizations, operational agencies, science communities, and private industry. Therefore, WaterNet: The NASA Water Cycle Solutions Network goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. WaterNet is a catalyst for discovery and sharing of creative solutions to water problems. It serves as a creative, discovery process that is the entry-path for a research-to-solutions systems engineering NASA framework, with the end result to ultimately improve decision support.

  9. Diluting ferric carboxymaltose in sodium chloride infusion solution (0.9% w/v) in polypropylene bottles and bags: effects on chemical stability

    PubMed Central

    Philipp, Erik; Braitsch, Michaela; Bichsel, Tobias; Mühlebach, Stefan

    2016-01-01

    Objectives This study was designed to assess the physicochemical stability of colloidal ferric carboxymaltose solution (Ferinject) when diluted and stored in polypropylene (PP) bottles and bags for infusion. Methods Two batches of ferric carboxymaltose solution (Ferinject) were diluted (500 mg, 200 mg and 100 mg iron in 100 mL saline) in PP bottles or bags under aseptic conditions. The diluted solutions were stored at 30°C and 75%±5% relative humidity (rH) for 72 h, and samples were withdrawn aseptically at preparation and after 24 h, 48 h and 72 h. Multiple parameters were used to test stability-related measures (pH, total iron and iron (II) content, molecular weight range determination, microbial contamination and particles count ≥10 μm). Results Overall, Ferinject diluted in 0.9% (w/v) NaCl solution and stored in PP bottles and bags was stable within the specifications for the complex and the acceptability limits set for all assays. In both containers, total iron content remained stable, within 10% of the theoretical iron content, and levels of iron (II) remained far below the threshold of acceptability. All preparations were free from sediments, particle numbers were acceptable and there was no microbial contamination. The molecular weight distribution and polydispersity index were also acceptable. Conclusions Under the tested experimental conditions, colloidal ferric carboxymaltose solution (Ferinject) diluted in saline in PP infusion bottles or bags demonstrated physical and chemical stability for up to 72 h at 30°C and 75% rH. Because of the lack of additional clinical data, when using ferric carboxymaltose, physicians/pharmacists should refer to the dilution and storing recommendations given in the product's summary of product characteristics. PMID:26835007

  10. Inactivation of tannins in milled sorghum grain through steeping in dilute NaOH solution.

    PubMed

    Adetunji, Adeoluwa I; Duodu, Kwaku G; Taylor, John R N

    2015-05-15

    Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. NaOH steeping substantially reduced assayable total phenols and tannins in both Type III and Type II sorghums and with Type III sorghum caused a 60-80% reduction in α-amylase inhibition compared to a 20% reduction by water steeping. NaOH treatment also reduced starch liquefaction time and increased free amino nitrogen. Type II tannin sorghum did not inhibit α-amylase and consequently the NaOH treatment had no effect. HPLC and LC-MS of the tannin extracts indicated a general trend of increasing proanthocyanidin/procyanidin size with increasing NaOH concentration and steeping time, coupled with a reduction in total area of peaks resolved. These show that the NaOH treatment forms highly polymerised tannin compounds, too large to assay and to interact with the α-amylase. NaOH pre-treatment of Type III sorghums could enable their utilisation in bioethanol production.

  11. Effects of electrolyte concentration and counterion valence on the microstructural flow regimes in dilute cetyltrimethylammonium tosylate micellar solutions.

    PubMed

    Tepale, N; Macías, E R; Bautista, F; Puig, J E; Manero, O; Gradzielski, M; Escalante, J I

    2011-11-15

    The shear thickening behavior and the transition to shear thinning are examined in dilute cetyltrimethylammonium tosylate (CTAT) micellar solutions as a function of surfactant concentration and ionic strength using electrolytes with different counterion valence. Newtonian behavior at low shear rates, followed by shear thickening and shear thinning at higher shear rates, are observed at low and intermediate surfactant and electrolyte concentrations. Shear thickening diminishes with increasing surfactant concentration and ionic strength. At higher surfactant or electrolyte concentration, only a Newtonian region followed by shear thinning is detected. A generalized flow diagram indicates two controlling regimes: one in which electrostatic screening dominates and induces micellar growth, and another, at higher electrolyte and surfactant concentrations, where chemical equilibrium among electrolyte and surfactant counterions controls the rheological behavior by modifying micellar breaking and reforming. Analysis of the shear thickening behavior reveals that not only a critical shear rate is required for shear thickening, but also a critical deformation, which appears to be unique for all systems examined, within experimental error. Moreover, a superposition of the critical shear rate for shear thickening with surfactant and electrolyte concentration is reported.

  12. Kinetic aspects of the coil-stretch transition of polymer chains in dilute solution under extensional flow

    NASA Astrophysics Data System (ADS)

    Hernández Cifre, J. G.; García de la Torre, J.

    2001-11-01

    When linear polymer chains in dilute solution are subject to extensional flow, each chain in the sample experiences the coil-stretch transition at a different time. Using Brownian dynamics simulation, we have studied the distribution of transition times in terms of the extensional rate and the length of the chains. If instead of time one characterizes the effect of the flow by the accumulated strain, then the distribution and its moments seem to take general forms, independent of molecular weight and flow rate, containing some numerical, universal constants that have been evaluated from the dynamical simulation. The kinetics of the transition, expressed by the time-dependence of the fraction of remaining coils, has also been simulated, and the results for the kinetic rate constant has been rationalized in a manner similar to that used for the transition time. The molecular individualism, characterized in this work by the distribution of transition times, is related to the excess of the applied extensional rate over its critical value, which will determine the transition time and other features of the coil-stretch transition.

  13. Brownian dynamics simulation study on the self-assembly of incompatible star-like block copolymers in dilute solution.

    PubMed

    Li, Bin; Zhu, You-Liang; Liu, Hong; Lu, Zhong-Yuan

    2012-04-14

    We study the self-assembly of symmetric star-like block copolymers (A(x))(y)(B(x))(y)C in dilute solution by using Brownian dynamics simulations. In the star-like block copolymer, incompatible A and B components are both solvophobic, and connected to the center bead C of the polymer. Therefore, this star-like block copolymer can be taken as a representative of soft and deformable Janus particles. In our Brownian dynamics simulations, these "soft Janus particles" are found to self-assemble into worm-like lamellar structures, loose aggregates and so on. By systematically varying solvent conditions and temperature, we build up the phase diagram to illustrate the effects of polymer structure and temperature on the aggregate structures. At lower temperatures, we can observe large worm-like lamellar aggregates. Upon increasing the temperature, some block copolymers detach from the aggregate; this phenomenon is especially sensitive for the polymers with less arms. The aggregate structure will be quite disordered when the temperature is high. The incompatibility between the two parts in the star-like block copolymer also affects the self-assembled structures. We find that the worm-like structure is longer and narrower as the incompatibility between the two parts is stronger. PMID:22395808

  14. Adsorption of small biological molecules on silica from diluted aqueous solutions: Quantitative characterization and implications to the Bernal's hypothesis

    NASA Astrophysics Data System (ADS)

    Basiuk, Vladimir A.; Gromovoy, Taras Yu.; Khil'Chevskaya, Elena G.

    1995-08-01

    To describe quantitatively the adsorption of prebiotically important compounds of low molecular weight (amino acids, short linear peptides, cyclic dipeptides, the Krebs's cycle and other carboxylic acids, nucleosides and related phosphates) on silica surface from diluted neutral aqueous solutions, equilibrium constants (K) and free energies (-ΔG) of adsorption were determined from the retention values measured by means of high-performance liquid chromatography on a silica gel column and from the isotherms measured under static conditions. For most carboxylic acids (including amino acids and linear peptides) -ΔG values were negative and K<1, thus showing very weak adsorption. Cyclic dipeptides (2,5-piperazinediones) exhibited higher adsorbability; -ΔG>0 and K>1 were found for most of them. Influence of the structure of α-substituent on the adsorbability is analyzed. A linear dependence of -ΔG on the number of aliphatic carbon atoms in a sorbate molecule was found for the series of aliphatic bifunctional amino acids, related dipeptides and 2,5-piperazinediones, as well as for the row from glycine to triglycyl glycine. The adsorption of nucleosides and their phosphates is characterized by much higherK and -ΔG values (of the order of 102 and 104, respectively). The adsorption data available from our work and literature are summarized and discussed with implications to the Bernal's hypothesis on the roles of solid surfaces in the prebiotic formation of biopolymers from monomeric ‘building blocks’.

  15. Temperature dependence of ion transport in dilute tetrabutylammonium triflate-acetate solutions and self-diffusion in pure acetate liquids.

    PubMed

    Bopege, Dharshani N; Petrowsky, Matt; Fleshman, Allison M; Frech, Roger; Johnson, Matthew B

    2012-01-12

    Conductivities and static dielectric constants for 0.0055 M tetrabutylammonium trifluoromethanesulfonate in n-butyl acetate, n-pentyl acetate, n-hexyl acetate, n-octyl acetate, and n-decyl acetate have been collected over the temperature range of 0-80 °C. Self-diffusion coefficients and static dielectric constants of pure acetates were obtained over the same temperature range. Both temperature-dependent diffusion coefficients and ionic conductivities of these pure acetates and dilute acetate solutions can be accurately described by the compensated Arrhenius formalism. Activation energies were calculated from compensated Arrhenius plots for both conductivity and diffusion data. Activation energies are higher for conductivity data of 0.0055 M TbaTf-acetates compared to diffusion data of pure acetates. The plot of the exponential prefactor versus the dielectric constant yields a single master curve for both conductivity and diffusion data. These data support the argument that mass and charge transport are thermally activated processes in the acetates, as previously observed in alcohol-based electrolytes. PMID:22145961

  16. Electrochemically enhanced removal of polycyclic aromatic basic dyes from dilute aqueous solutions by activated carbon cloth electrodes.

    PubMed

    Bayram, Edip; Ayranci, Erol

    2010-08-15

    Open-circuit (OC) adsorption and electrosorption behaviors of three polycyclic aromatic dyes from dilute aqueous solutions onto activated carbon cloth (ACC) were investigated. The selected dyes were crystal violet (BB-3), basic blue7 (BB-7), and basic blue11 (BB-11). OC adsorption and electrosorption processes were monitored by in situ UV-visible spectrophotometry. Electrosorption was carried out by polarization of an ACC electrode, galvanostatically. Considerable enhancements in removal capacity and duration of the dyes were achieved upon polarization of ACC. Kinetic data for OC adsorption and electrosorption were successfully treated according to pseudo-first-order law, and rate constants were determined. Adsorption isotherms were derived, and the data were treated according to Langmuir and Freundlich equations. Both the rate and extent of adsorption and electrosorption of dyes were found to increase in the order of BB-7 < BB-11 < BB-3. This order was discussed in terms of correlation between sizes of dye species and of ACC pores. Electrodesorption experiments were carried out to explore possibilities of regeneration of ACC. PMID:20704233

  17. CO sub 2 induced inhibition of the localized corrosion of aluminum, Al-0. 5% Cu, and Al-2% Cu in dilute HF solution

    SciTech Connect

    Scully, J.R. . Dept. of Materials Science); Peebles, D.E. )

    1991-01-01

    This study presents work on corrosion of aluminum, Al-.5% Cu, and Al-2% Cu. Electrochemical tests were performed in dilute HF solutions both with and without CO{sub 2} sparging. It is suggested that CO{sub 2} or its reaction products interact with the passive film so that exposure of Cu in the oxide-solution interface is minimized. CO{sub 2} is investigated as a corrosion inhibitor. 4 refs. (JDL)

  18. Synthesis of fast response crosslinked PVA-g-NIPAAm nanohydrogels by very low radiation dose in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Fathi, Marziyeh; Reza Farajollahi, Ali; Akbar Entezami, Ali

    2013-05-01

    Nanohydrogels of poly(vinyl alcohol)-g-N-isopropylacrylamide (PVA-g-NIPAAm) are synthesized by PVA and NIPAAm dilute aqueous solution using much less radiation dose of 1-20 Gy via intramolecular crosslinking at ambient temperature. The radiation synthesis of nanohydrogels is performed in the presence of tetrakis (hydroxymethyl) phosphonium chloride (THPC) due to its rapid oxygen scavenging abilities and hydrogen peroxide (H2O2) as a source of hydroxyl radicals. The effect of radiation dose, feed composition ratio of PVA and H2O2 is investigated on swelling properties such as temperature and pH dependence of equilibrium swelling ratio as well as deswelling kinetics. Experimental data exhibit high equilibrium swelling ratio and fast response time for the synthesized nanohydrogels. The average molecular weight between crosslinks (Mc) and crosslinking density (ρx) of the obtained nanohydrogels are calculated from swelling data as a function of radiation dose, H2O2 and PVA amount. Fourier transform infrared spectroscopy (FT-IR), elemental analysis of nitrogen content and thermogravimetric analysis (TGA) are used to confirm the grafting reaction. Lower critical solution temperature (LCST) is measured around 33 °C by differential scanning calorimetry (DSC) for PVA-g-NIPAAm nanohydrogels. Dynamic light scattering (DLS) data demonstrate that the increase of radiation dose leads to the decreasing in dimension of nanohydrogels. Also, rheological studies are confirmed an improvement in the mechanical properties of the nanohydrogels with increasing the radiation dose. A cytotoxicity study exhibits a good biocompatibility for the obtained nanohydrogels. The prepared nanohydrogels show fast swelling/deswelling behavior, high swelling ratio, dual sensitivity and good cytocompatibility, which may find potential applications as biomaterial.

  19. Stress in a dilute suspension of spheres in a dilute polymer solution subject to simple shear flow at finite Deborah numbers

    NASA Astrophysics Data System (ADS)

    Koch, Donald L.; Lee, Eric F.; Mustafa, Ibrahim

    2016-05-01

    The influence of particle-polymer interactions on the ensemble average stress is derived as a function of the Deborah number for a dilute suspension of spheres in an Oldroyd-B fluid in the limit of small polymer concentrations. The slow rate of decay of the particle-induced polymer stress with separation from a particle presents a challenge to the derivation of the average stress, which can be overcome by removing the linearized polymer stress disturbance before computing the bulk average stress from the particle-induced disturbance. The linearized stress can be shown to have zero ensemble average. The polymer influence on the particle's stresslet is computed with the aid of a generalized reciprocal theorem based on a regular perturbation from Newtonian flow for small polymer concentration. The analysis shows that the particle-polymer contributions to the shear stress and first normal stress difference shear thicken as has been observed in the experiments of Scirocco et al. [Shear thickening in filled Boger fluids, J. Rheol. 49, 551 (2005), 10.1122/1.1849185]. The particle-polymer contribution to the second normal stress difference is positive at small Deborah numbers but changes sign at a Deborah number of about 2.3.

  20. Dilute acid/metal salt hydrolysis of lignocellulosics

    DOEpatents

    Nguyen, Quang A.; Tucker, Melvin P.

    2002-01-01

    A modified dilute acid method of hydrolyzing the cellulose and hemicellulose in lignocellulosic material under conditions to obtain higher overall fermentable sugar yields than is obtainable using dilute acid alone, comprising: impregnating a lignocellulosic feedstock with a mixture of an amount of aqueous solution of a dilute acid catalyst and a metal salt catalyst sufficient to provide higher overall fermentable sugar yields than is obtainable when hydrolyzing with dilute acid alone; loading the impregnated lignocellulosic feedstock into a reactor and heating for a sufficient period of time to hydrolyze substantially all of the hemicellulose and greater than 45% of the cellulose to water soluble sugars; and recovering the water soluble sugars.

  1. Traceable values for nitrate in water samples by isotope dilution analysis using a small thermionic quadrupole mass spectrometer.

    PubMed

    Wolff, J C; Taylor, D P; De Bièvre, P

    1996-09-15

    An isotope dilution mass spectrometric procedure was developed for the determination of nitrate in water samples. The isotope dilution experiments were carried out using the Institute for Reference Materials and Measurements's 15N-enriched nitrate spike reference material IRMM-627. Nitrate was isolated from the matrix by precipitating it as nitron nitrate, from which emission of negative thermal NO2-ions was found to be best. The ions were produced in the ion source of a small, low-cost, easy-to-handle thermionic quadrupole mass spectrometer equipped with a secondary electron multiplier coupled to an ion counter. The procedure developed was applied to the measurement of nitrate in a certified reference material (stimulated rainwater, CRM 409 from Community Bureau of Reference), in sparkling mineral water, and in tap water. Results were compared with those obtained using ion chromatography. Good agreement (within 1%) was found between the concentration determined by isotope dilution mass spectrometry, the values from ion chromatography, and the certified value. The procedure developed allowed accurate and traceable determinations of nitrate in water samples, with an expanded uncertainty (coverage factor k = 2) of 2-5%, and the detection limit was found to be 2 mumol kg-1.

  2. Water & Aqueous Solutions. Final Progress Report

    SciTech Connect

    2002-08-09

    The Gordon Research Conference (GRC) on Water & Aqueous Solutions was held at Holderness School, New Hampshire, 8/4/02 thru 8/9/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  3. Characterization of lignin derived from water-only and dilute acid flowthrough pretreatment of poplar wood at elevated temperatures

    DOE PAGESBeta

    Zhang, Libing; Yan, Lishi; Wang, Zheming; Laskar, Dhrubojyoti D.; Swita, Marie S.; Cort, John R.; Yang, Bin

    2015-12-01

    In this study, flowthrough pretreatment of biomass has high potential to valorize lignin derivatives to high-value products, which is vital to enhance the economy of biorefinery plants. Comprehensive understanding of lignin behaviors and solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of providing flexible platform for lignin utilization. In this study, the effects of flowthrough pretreatment conditions on lignin separation from poplar wood were reported as well as the characteristics of three sub-sets of lignin produced from the pretreatment, including residual lignin in pretreated solid residues (ReL),more » recovered insoluble lignin in pretreated liquid (RISL), and recovered soluble lignin in pretreatment liquid (RSL). Both the water-only and 0.05% (w/w) sulfuric acid pretreatments were performed at temperatures from 160 to 270°C on poplar wood in a flowthrough reactor system for 2-10 min. Results showed that water-only flowthrough pretreatment primarily removed syringyl (S units). Increased temperature and/or the addition of sulfuric acid enhanced the removal of guaiacyl (G units) compared to water-only pretreatments at lower temperatures, resulting in nearly complete removal of lignin from the biomass. Results also suggested that more RISL was recovered than ReL and RSL in both dilute acid and water-only flowthrough pretreatment at elevated temperatures. NMR spectra of the RISL revealed significant β-O-4 cleavage, α-β deoxygenation to form cinnamyl-like end groups, and slight β-5 repolymerization in both water-only and dilute acid flowthrough pretreatments. In conclusion, elevated temperature and/or dilute acid greatly enhanced lignin removal to almost 100% by improving G unit removal besides S unit removal in flowthrough system. A new lignin chemistry transformation pathway was proposed and revealed the complexity of lignin structural change

  4. Reuse of recalcitrant-rich anaerobic effluent as dilution water after enhancement of biodegradability by Fenton processes.

    PubMed

    Arimi, Milton M; Zhang, Yongjun; Namango, Saul S; Geißen, Sven-Uwe

    2016-03-01

    Anaerobic digestion is used to treat effluents with a lot of organics, such as molasses distillery wastewater (MDW) which is the effluent of bioethanol production from molasses. The raw MDW requires a lot of dilution water before biodigestion, while the digested MDW has high level of recalcitrants which are problematic for its discharge. This study investigated ferric coagulation, Fenton, Fenton-like (with ferric ions as catalyst) processes and their combinations on the biodegradability of digested MDW. The Fenton and Fenton-like processes after coagulation increased the MDW biodegradability defined by (BOD5/COD) from 0.07 to (0.4-0.6) and saved 50% of H2O2 consumed in the classic Fenton process. The effluent from coagulation coupled to a Fenton-like process was used as dilution water for the raw MDW before the anaerobic digestion. The process was stable with volumetric loading of approx. 2.7 g COD/L/d. It resulted in increased overall biogas recovery and significantly decreased the demand for the dilution water. PMID:26692412

  5. Model nitride irradiated nuclear fuel: production, reaction with water and dilution in nitric acid

    SciTech Connect

    Dvoeglazov, K.; Glushenkov, A.; Sharin, A.; Arseenkov, L.; Lobachev, E.; Davydov, A.; Chebotarev, A.

    2013-07-01

    Samples of the model nuclear fuel (MNF) were made from separately synthesized nitride powders uranium-plutonium, zirconium, lanthanum and metal additives of simulators (Mo, Pd, Rh, Ag) fission products. Synthesis of initial nitride components was carried out from individual oxides, using a carbo-thermal restoration method. From MNF samples baked at a temperature of 1750 C. degrees, were made ceramographic specimens which were investigated by a scanning electron microscope. The analysis showed that distribution of the MNF components and structure of the samples corresponds to distribution of these components in the irradiated nitride fuel. The samples of MNF of nitride fuel were used for carrying out researches on dissolution in water and nitric acid. Experiments on studying the interaction of MNF with water have been made at 20, 50 and 80 C. degrees. The speed of leaching has been determined by a way of measuring the activity of water (Bq/l) in time. It is shown that an increase of temperature leads to an increase of the speed of leaching of plutonium. The formation of a precipitation, allegedly polymeric forms of plutonium, has been observed. The estimated speed of leaching of plutonium from MNF in water at 80 C. degrees is -0,0064 μgPu/(mm{sup 2}*h). From elements of FP simulators, molybdenum appears to be the most significantly leached. The dissolution of MNF in nitric acid (7,8 and 9,4 mol/l) has been carried out at boiling temperature (106-109 C. degrees). During the process of dissolution, gases were emitted. The assessment of composition of the emitted gases has been carried out. During the filtering of the solutions a precipitate whose weight makes about 2% from the weight of initial fuel has been found. Precipitate represents small powder of metal with gray color. Precipitate was investigated by a scanning electron microscope. The analysis of ranges of absorption of solution showed that the Pu(VI) share to the general content of plutonium in solution can

  6. Waters associated with an active basaltic volcano, Kilauea, Hawaii: Variation in solute sources, 1973-1991

    USGS Publications Warehouse

    Tilling, R.I.; Jones, B.F.

    1996-01-01

    Chemical and isotopic analyses of samples collected from a 1262-m-deep research borehole at the summit of Kilauea Volcano provide unique time-series data for composition of waters in the uppermost part of its hydrothermal system. These waters have a distinctive geochemical signature: a very low proportion of chloride relative to other anions compared with other Hawaiian wa-ters - thermal (???30 ??C) or nonthermal (<30 ??C) - and with most thermal waters of the world. Isotope data demonstrate that the borehole waters are of essentially meteoric origin, with minimal magmatic input. The water chemistry exhibits marked temporal variations, including pronounced short-term (days to weeks) effects of rainfall dilution and longer term (months to years) decline of total solutes. The 1973-1974 samples are Na-sulfate-dominant, but samples collected after July 1975 are (Mg + Ca)-bicarbonate-dominant. This compositional shift, probably abrupt, was associated with an increase in the partial pressure of CO2 (PCO2) related to volcanic degassing of CO2 accompanying a large eruption (December 31, 1974) and associated intense seismicity. Following the initial sharp increase, the PCO2 then decreased, approaching preemption values in April 1976. Beginning in mid-1975, solute concentrations of the borehole waters decreased substantially, from ???45 meq/L to <25 meq/L in only eight months; by 1991, total solute concentrations were <17 meq/L. This decline in solutes cannot be attributed to rainfall dilution and is inferred to reflect the decreasing availability with time of the easily leachable salts of alkali metals and sulfate, which originated in sublimates and fumarolic encrustations in fractures and cavities of rocks along the hydrologic flow paths. The overall chemistry of the summit-borehole waters is largely determined by hydrolysis reactions associated with normal weathering of host tholeiitic basalts on a geologic time scale, despite short-term perturbations in composition

  7. Raman spectroscopic analysis of supersaturated aqueous solution of MgO·B 2O 3-32%MgCl 2-H 2O during acidification and dilution

    NASA Astrophysics Data System (ADS)

    Zhihong, Liu; Bo, Gao; Shuni, Li; Mancheng, Hu; Shuping, Xia

    2004-11-01

    Raman spectra of supersaturated aqueous solution of MgO·B 2O 3-32%MgCl 2-H 2O during acidification/alkalization and dilution have been studied. The assignments of the recorded Raman shift are given. The main existing forms of polyborate anions and their interaction in borate aqueous solution have been proposed through spectroscopic analysis. The experimental results indicate that the higher concentration of cation are beneficial not only to the dissolution of boric acid but also to the polymerization of polyborate anions. The existing forms and interaction among them also depend on the concentration of boron and the pH value in solution.

  8. An evaluation of dilution models for the discharge of produced water into the Gulf of Mexico

    SciTech Connect

    Tomasko, D.

    1993-11-01

    A study was performed to determine which of two mixing models (CORMIX1 or UM/PLUMES) was more appropriate for simulating the vertically downward discharge of negatively buoyant produced waters into a stratified ambient having a crossflow in Gulf of Mexico waters. For deep waters without impingement on the seafloor or gravitational collapse of the plume, UM/PLUMES is recommended because of its Lagrangian solution to the governing equations of mass, momentum, and energy. CORMIXI is recommended if the plume interacts with the seafloor or if the plume undergoes gravitational collapse, although its results may be overly conservative at the edge of the mixing zone. These overly conservative results can be corrected by employing a post-processing technique developed by Limno-Tech, Inc. and Wright. Because neither model was specifically designed to simulate the entire discharge scenario, additional work is recommended. This work includes laboratory and field studies to generate additional validation data, and code modifications to enhance the capabilities of the models and reduce uncertainty in the predicted jet behavior and potential errors in post processing model results.

  9. Experimental investigation of compound-specific dilution of solute plumes in saturated porous media: 2-D vs. 3-D flow-through systems.

    PubMed

    Ye, Yu; Chiogna, Gabriele; Cirpka, Olaf; Grathwohl, Peter; Rolle, Massimo

    2015-01-01

    Dilution of solute plumes in groundwater strongly depends on transverse mixing. Thus, the correct parameterization of transverse dispersion is of critical importance for the quantitative description of solute transport. In this study we perform flow-through laboratory experiments to investigate the influence of transport dimensionality on transverse mixing. We present a high-resolution experimental setup to study solute dilution and transverse dispersion in three-dimensional porous media. We conduct multi-tracer experiments in the new 3-D setup and compare the results with the outcomes of analogous tracer experiments performed in a quasi 2-D system. We work under steady-state flow and transport conditions and consider a range of velocities relevant for groundwater flow (0.5-8 m/day). Transverse dispersion coefficients are determined from high-resolution concentration profiles at the outlet of the flow-through chambers (7×7 ports in the 3-D setup and 7 ports in the quasi 2-D system), considering conservative tracers with significantly different aqueous diffusion coefficients, namely fluorescein and dissolved oxygen. To quantify dilution in the 2-D and 3-D systems, we experimentally determine the flux-related dilution index using the flow rates and the concentrations measured at the inlet and outlet ports, and we propose semi-analytical expressions to predict its evolution with travel distance in uniform groundwater flow. The experimental results in the quasi 2-D and 3-D flow-through systems are consistent and show a compound-specific behavior of the transverse dispersion coefficient and its non-linear dependence on the seepage velocity in both setups. The degree of dilution and the compound-specific effects of transverse dispersion are considerably more pronounced in 3-D than in quasi 2-D transport systems.

  10. Lattice model for water-solute mixtures

    NASA Astrophysics Data System (ADS)

    Furlan, A. P.; Almarza, N. G.; Barbosa, M. C.

    2016-10-01

    A lattice model for the study of mixtures of associating liquids is proposed. Solvent and solute are modeled by adapting the associating lattice gas (ALG) model. The nature of interaction of solute/solvent is controlled by tuning the energy interactions between the patches of ALG model. We have studied three set of parameters, resulting in, hydrophilic, inert, and hydrophobic interactions. Extensive Monte Carlo simulations were carried out, and the behavior of pure components and the excess properties of the mixtures have been studied. The pure components, water (solvent) and solute, have quite similar phase diagrams, presenting gas, low density liquid, and high density liquid phases. In the case of solute, the regions of coexistence are substantially reduced when compared with both the water and the standard ALG models. A numerical procedure has been developed in order to attain series of results at constant pressure from simulations of the lattice gas model in the grand canonical ensemble. The excess properties of the mixtures, volume and enthalpy as the function of the solute fraction, have been studied for different interaction parameters of the model. Our model is able to reproduce qualitatively well the excess volume and enthalpy for different aqueous solutions. For the hydrophilic case, we show that the model is able to reproduce the excess volume and enthalpy of mixtures of small alcohols and amines. The inert case reproduces the behavior of large alcohols such as propanol, butanol, and pentanol. For the last case (hydrophobic), the excess properties reproduce the behavior of ionic liquids in aqueous solution.

  11. WaterNet: The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Belvedere, D. R.; Houser, P. R.; Imam, B.; Schiffer, R.; Schlosser, C. A.; Gupta, H. V.; Welty, C.; Vorosmarty, C.; Matthews, D.; Lawford, R.

    2006-05-01

    The water cycle is continuously being transformed by climate change, erosion, pollution, salinization, and engineering practices, and is central to drought, flood, and disease hazards. Therefore, it is a national priority is to use advancements in scientific observations and knowledge to develop solutions to society's water challenges. NASA's unique role in this national priority is to exploit its unique view from space to improve water and energy cycle monitoring and prediction. As such, NASA's Earth science programs have collected substantial water cycle information and knowledge that must be integrated and shared to develop solutions in all twelve national priority application areas. However, NASA alone cannot achieve the ultimate goal of improved operational environmental assessments, predictions and applications and therefore must establish collaborations and interoperability with existing networks and nodes of research organizations, operational agencies, the scientific community, and private industry. Therefore, we propose to develop WaterNet: The NASA Water Cycle Solutions Network whose goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. We will develop WaterNet by engaging relevant NASA water and energy cycle resources and community-of-practice organizations to develop what we term an "actionable database" that can be used to communicate and connect NASA Water and energy cycle focus area research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing the many existing highly valuable water-related science and application networks, we will focus a balance of our efforts to enable their interoperability in a solutions network context. We will initially focus on identifying, collecting information about, and analyzing the

  12. Impacts of global change on the concentrations and dilution of combined sewer overflows in a drinking water source.

    PubMed

    Jalliffier-Verne, Isabelle; Leconte, Robert; Huaringa-Alvarez, Uriel; Madoux-Humery, Anne-Sophie; Galarneau, Martine; Servais, Pierre; Prévost, Michèle; Dorner, Sarah

    2015-03-01

    This study presents an analysis of climate change impacts on a large river located in Québec (Canada) used as a drinking water source. Combined sewer overflow (CSO) effluents are the primary source of fecal contamination of the river. An analysis of river flowrates was conducted using historical data and predicted flows from a future climate scenario. A spatio-temporal analysis of water quality trends with regard to fecal contamination was performed and the effects of changing flowrates on the dilution of fecal contaminants were analyzed. Along the river, there was a significant spatial trend for increasing fecal pollution downstream of CSO outfalls. Escherichia coli concentrations (upper 95th percentile) increased linearly from 2002 to 2012 at one drinking water treatment plant intake. Two critical periods in the current climate were identified for the drinking water intakes considering both potential contaminant loads and flowrates: local spring snowmelt that precedes river peak flow and extra-tropical storm events that occur during low flows. Regionally, climate change is expected to increase the intensity of the impacts of hydrological conditions on water quality in the studied basin. Based on climate projections, it is expected that spring snowmelt will occur earlier and extreme spring flowrates will increase and low flows will generally decrease. High and low flows are major factors related to the potential degradation of water quality of the river. However, the observed degradation of water quality over the past 10 years suggests that urban development and population growth may have played a greater role than climate. However, climate change impacts will likely be observed over a longer period. Source water protection plans should consider climate change impacts on the dilution of contaminants in addition to local land uses changes in order to maintain or improve water quality.

  13. The interaction mechanisms of triacontane paraffin with semi-crystalline poly(ethylene-butene) random copolymers in dilute solution studied with SANS

    NASA Astrophysics Data System (ADS)

    Radulescu, A.; Schwahn, D.; Monkenbusch, M.; Richter, D.; Fetters, L. J.

    2004-07-01

    Two interaction mechanisms take place when paraffin wax is mixed with a random copolymer of ethylene and butene in dilute solution: either a polymer-paraffin co-crystallization or a paraffin crystallization on the polymer template occur. We present here a quantitative analysis of the SANS results obtained from an aggregation behavior of the PEB-7.5 copolymer and triacontane (C30) paraffin in decane. This mixture best displays both interaction mechanisms as they depend on the solution conditions (temperature, paraffin content). The geometrical and density parameters of the aggregates were obtained using a structural model derived on the basis of the identified morphologies.

  14. Effects of dilute substitutional solutes on interstitial carbon in α-Fe: Interactions and associated carbon diffusion from first-principles calculations

    NASA Astrophysics Data System (ADS)

    Liu, Peitao; Xing, Weiwei; Cheng, Xiyue; Li, Dianzhong; Li, Yiyi; Chen, Xing-Qiu

    2014-07-01

    By means of first-principles calculations coupled with the kinetic Monte Carlo simulations, we have systematically investigated the effects of dilute substitutional solutes on the behaviors of carbon in α-Fe. Our results uncover the following. (i) Without the Fe vacancy the interactions between most solutes and carbon are repulsive due to the strain relief, whereas Mn has a weak attractive interaction with its nearest-neighbor carbon due to the local ferromagnetic coupling effect. (ii) The presence of the Fe vacancy results in attractive interactions of all the solutes with carbon. In particular, the Mn-vacancy pair shows an exceptionally large binding energy of -0.81 eV with carbon. (iii) The alloying addition significantly impacts the atomic-scale concentration distributions and chemical potential of carbon in the Fe matrix. Among them, Mn and Cr increase the carbon chemical potential, whereas Al and Si reduce it. (iv) Within the dilute scale of the alloying solution, the solute concentration- and temperature-dependent carbon diffusivities demonstrate that Mn has a little impact on the carbon diffusion, whereas Cr (Al or Si) remarkably retards the carbon diffusion. Our results provide a certain implication for better understanding the experimental observations related with the carbon solubility limit, carbon microsegregation, and carbide precipitations in the ferritic steels.

  15. Recirculating cooling water solute depletion models

    SciTech Connect

    Price, W.T.

    1990-03-16

    Chromates have been used for years to inhibit copper corrosion in the plant Recirculating Cooling Water (RCW) system. However, chromates have become an environmental problem in recent years both in the chromate removal plant (X-616) operation and from cooling tower drift. In response to this concern, PORTS is replacing chromates with Betz Dianodic II, a combination of phosphates, BZT, and a dispersant. This changeover started with the X-326 system in 1989. In order to control chemical concentrations in X-326 and in systems linked to it, we needed to be able to predict solute concentrations in advance of the changeover. Failure to predict and control these concentrations can result in wasted chemicals, equipment fouling, or increased corrosion. Consequently, Systems Analysis developed two solute concentration models. The first simulation represents the X-326 RCW system by itself; and models the depletion of a solute once the feed has stopped. The second simulation represents the X-326, X-330, and the X-333 systems linked together by blowdown. This second simulation represents the concentration of a solute in all three systems simultaneously. 4 figs.

  16. Experimental investigation of sulphur isotope partitioning during outgassing of hydrogen sulphide from diluted aqueous solutions and seawater.

    PubMed

    Baune, Claudia; Bottcher, Michael E

    2010-12-01

    The diffusion of hydrogen sulphide across the sediment-water interface and subsequent liberation to the atmosphere may occur in iron-deficient coastal marine environments with enhanced microbial activity in surface sediments and corresponding accumulation of dissolved H2S in near-surface pore waters. The involvement of analogue processes in periods of global mass extinctions during Earth's history (e.g. at the Permian-Triassic boundary) is currently in discussion [L.R. Kump, A. Pavlov, and M. Arthur,Massive Release of Hydrogen Sulfide to the Surface Ocean and Atmosphere During Intervals of Oceanic Anoxia, Geology 33, 397 (2005)]. The outgassing of H₂S is associated with a fractionation of the stable sulphur isotopes, which has so far only been investigated experimentally at selected acidic and neutral pH values, and no experiments with seawater had been carried out. In this communication, we report on sulphur isotope fractionation that takes place during the experimental degassing of H₂S from aqueous solution by an inert gas (N₂) at 21 °C. Experiments were conducted in the pH range between 2.6 and 10.8, corresponding to the dominance fields of dissolved hydrogen sulphide (H₂S(aq)), bisulphide (HS-(aq)), and mixtures of both sulphide species. Overall isotope enrichment factors between -1.6 and +3.0‰ were observed, with the residual dissolved sulphide being enriched or depleted in ³⁴S compared to the liberated H₂S at low and high pH values, respectively. The difference in the low and high pH isotope fractionation effects can be explained by isotope exchange between H₂S(aq) and HS-(aq) [B. Fry, H. Gest, and J.M. Hayes, Sulfur Isotope Effects Associated with Protonation of HS- and Volatilization of H₂S, Chem. Geol. (Isot. Geosci. Sec.) 58, 253 (1986); R. Geßler and K. von Gehlen, Investigation of Sulfur Isotope Fractionation Between H2S Gas and Aqueous Solutions, Fresenius J. Anal. Chem. 324, 130 (1986)] followed by the subsequent transfer of H

  17. Trace analysis of acidic pharmaceutical residues in waters with isotope dilution gas chromatography-mass spectrometry via methylation derivatization.

    PubMed

    Hu, Ruikang; Yang, Zhaoguang; Zhang, Lifeng

    2011-09-30

    Acidic pharmaceutical residues are pollutants of emerging concern and are generally monitored by HPLC-MS/MS. However, due to the limited separation efficiency of HPLC column and lack of suitable mass transition for confirmation analysis, some interference may not be separated completely and differentiated from ibuprofen, which may cause the results with interference, especially in sample with complex matrix. The objective of this study is to develop a sensitive and reliable method for the determination of acidic pharmaceutical residues in water samples by GC-MS with better resolution by using methylation derivatization and isotope dilution techniques. TMSDM, a mild reagent, was used as the derivatization reagent coupling with the isotope dilution technique, for the first time, to improve the precision and accuracy of the analytical method to determine the pharmaceutical residues in water. The MDLs for the five acidic organic compounds: ibuprofen, gemfibrozil, naproxen, ketoprofen and diclofenac were from 0.7 to 1.1 ng/L, with recoveries ranging from 93 to 110%. Alternative to the HPLC-MS/MS method, the developed GC-MS protocols provides an additional option for the analysis of acidic pharmaceutical residues in water, with better separation efficiency in reducing interferences from complicated sample matrix, for determination of ibuprofen residues.

  18. Precision of a field method for determination of pH in dilute lakes

    USGS Publications Warehouse

    Turk, J.T.

    1986-01-01

    Replicate pH measurements in three dilute lakes made during extreme conditions indicate that pH can be measured in the field with a variance due to measurement error of 0.005 unit. Error of the field technique in measuring the pH of dilute solutions in the laboratory ranges from less than 0.01 unit in dilute strong-acid solutions to about 0.05 unit in air-saturated deionized water.

  19. Effect of pH Value on the Electrochemical and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in the Dilute Bicarbonate Solutions

    NASA Astrophysics Data System (ADS)

    Cui, Z. Y.; Liu, Z. Y.; Wang, L. W.; Ma, H. C.; Du, C. W.; Li, X. G.; Wang, X.

    2015-11-01

    In this work, effects of pH value on the electrochemical and stress corrosion cracking (SCC) behavior of X70 pipeline steel in the dilute bicarbonate solutions were investigated using electrochemical measurements, slow strain rate tensile tests and surface analysis techniques. Decrease of the solution pH from 6.8 to 6.0 promotes the anodic dissolution and cathodic reduction simultaneously. Further decrease of the pH value mainly accelerates the cathodic reduction of X70 pipeline steel. As a result, when the solution pH decreases form 6.8 to 5.5, SCC susceptibility decreases because of the enhancement of the anodic dissolution. When the solution pH decreases from 5.5 to 4.0, SCC susceptibility increases gradually because of the acceleration of cathodic reactions.

  20. Near-IR Band Strengths of Molecules Diluted in Nitrogen and Water Ices

    NASA Astrophysics Data System (ADS)

    Richey, Christina; Gerakines, P. A.

    2010-10-01

    In order to determine the column density of a component of an ice from its infrared absorption features, the strengths of these features must be known. The peak positions, widths, profiles, and strengths of a certain ice component's infrared absorption features are affected be the overall composition of the ice (Quirico et al. 1999). Many satellites within the solar system have surfaces that are dominated by either N2 or H2O (Roush 2001). The experiments presented here focus on the near -infrared absorption features of CO, CO2, CH4, and NH3 (λ =10,000-4,000 cm-1, ν =1-2.5 μm) and the effects of diluting these molecules in N2 and H2O ice (dilution of 5:1). This is a continuation of previous results published by the Astro- and Solar-System Program at UAB by Gerakines et al. (2005). These data may be used to determine ice abundances from observed near-IR spectra or to predict the sizes of near-IR features in astrophysical environments.

  1. Transmittance of distilled water and sodium-chloride-water solutions

    SciTech Connect

    Kanayama, K.; Baba, H.

    1988-05-01

    The spectral transmittance of pure water and salt water solutions of various concentrations, which are important for the thermal calculation of a solar pond, is measured experimentally for specimen thickness of 1 to 100 mm by means of an autorecording spectro-radiometer inside an air-conditioned room. On the basis of the measured spectral transmittance, the total transmittance of pure and salty waters to 3 m of water depth is calculated as a ratio of the total radiation energy over all wavelengths arriving at any depth from the water surface of the solar pond to the solar radiation incident upon the water surface with various air masses. According to Nielsens' four-partition method, the effective absorption coefficient is calculated for each wavelength band. Lastly, the transmission properties obtained for pure water, i.e., spectral and total transmittances, absorption wavelength band, and effective absorption coefficient, are compared with past results, and those for salty water with various concentrations are compiled as basic data for the use of solar energy by a solar pond.

  2. Dynamical properties of water-methanol solutions.

    PubMed

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Vasi, Cirino; Vasi, Sebastiano; Stanley, H Eugene

    2016-02-14

    We study the relaxation times tα in the water-methanol system. We examine new data and data from the literature in the large temperature range 163 < T < 335 K obtained using different experimental techniques and focus on how tα affects the hydrogen bond structure of the system and the hydrophobicity of the alcohol methyl group. We examine the relaxation times at a fixed temperature as a function of the water molar fraction XW and observe two opposite behaviors in their curvature when the system moves from high to low T regimes. This behavior differs from that of an ideal solution in that it has excess values located at different molar fractions (XW = 0.5 for high T and 0.75 in the deep supercooled regime). We analyze the data and find that above a crossover temperature T ∼ 223 K, hydrophobicity plays a significant role and below it the water tetrahedral network dominates. This temperature is coincident with the fragile-to-strong dynamical crossover observed in confined water and supports the liquid-liquid phase transition hypothesis. At the same time, the reported data suggest that this crossover temperature (identified as the Widom line temperature) also depends on the alcohol concentration.

  3. Analysis of organophosphate flame retardants and plasticisers in water by isotope dilution gas chromatography-electron ionisation tandem mass spectrometry.

    PubMed

    Teo, Tiffany L L; McDonald, James A; Coleman, Heather M; Khan, Stuart J

    2015-10-01

    The widespread use of organophosphate flame retardants (PFRs) in commercial products have led to their increased presence in the environment. In this study, a rapid and reliable analytical method was developed for the analysis of five PFRs in water using gas chromatography tandem mass spectrometry (GC-MS/MS) with electron ionisation (EI) and a run time of 13 min. The PFRs investigated were tributyl phosphate (TBP), tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCP) and triphenyl phosphate (TPP). Solid phase extraction (SPE) was undertaken to extract and concentrate target analytes from aqueous matrices. All water samples were extracted from a volume of 500 mL. Isotopically labelled compounds were used to account for analytical variability and for accurate quantification by isotope dilution. Method recoveries for all compounds were above 80% in all tested water samples. Method detection limits for all target analytes ranged from 0.3 to 24 ng/L in ultrapure water, tap water, seawater, surface water, secondary effluent and swimming pool water. Validation of this method confirmed satisfactory method stability with less than 1% coefficients of variation, verifying that this approach produced good reproducibility. PMID:26078137

  4. The measurement of extravascular lung water by thermal-green dye indicator dilution.

    PubMed

    Lewis, F R; Elings, V B; Hill, S L; Christensen, J M

    1982-01-01

    The theory and practice of the thermal-dye indicator-dilution method for measurement of EVLW has been discussed, and all available animal data from our laboratory correlating EVTV and gravimetric EVLW have been presented. The method appears to function well over the entire range of edema seen , and to be minimally dependent on cardiac output. Thermal-indicator loss does not seem to be a significant problem and does not impair the accuracy of this method. Out results are consistent with earlier works in the field in identifying significant differences between the isotopic EVLW methods and the thermal-dye method, and it seems likely that these differences are due to the much greater diffusion rate of the thermal indicator.

  5. Simultaneous determination of alachlor, metolachlor, atrazine, and simazine in water and soil by isotope dilution gas chromatography/mass spectrometry

    SciTech Connect

    Huang, L.Q.

    1989-03-01

    A multiresidue method was developed for the simultaneous determination of low parts per billion (ppb) concentrations of the herbicides alachlor, metolachlor, atrazine, and simazine in water and soil using isotope dilution gas chromatography/mass spectrometry (GC/MS). Known amounts of /sup 15/N,/sup 13/C-alachlor and /sup 2/H/sub 5/-atrazine were added to each sample as internal standards. The samples were then prepared by a solid phase extraction with no further cleanup. A high resolution GC/low resolution MS system with data acquisition in selected ion monitoring mode was used to quantitate herbicides in the extract. The limit of detection was 0.05 ppb for water and 0.5 ppb for soil. Accuracy greater than 80% and precision better than 4% was demonstrated with spiked samples.

  6. Backward stimulated Raman scattering in water and water solutions

    NASA Astrophysics Data System (ADS)

    Kudryavtseva, Anna D.; Baranov, Anatolii N.; Sokolovskaya, Albina I.; Tcherniega, Nicolaii V.; Barille, Regis; Rivoire, Genevieve

    2001-02-01

    12 Energetical and spectral characteristics of backward stimulated Raman scattering (BSRS) in water and water solutions of organic liquids (acetone, benzene, ethanol, cyclohexane) at different excitation conditions have been experimentally investigated. Maximum conversion efficiency of laser light into BSRS wave was about 40%. For picosecond range experimental results and calculations are presented showing the BSRS intensity as a function of the main experimental parameters concerning the geometry of excitation and the exciting intensity. Thus it's possible to forecast the best experimental set-up in term of BSRS efficiencies and to estimate the minimum length of water necessary to detect BSRS. Competition with other scatterings is observed. In nanosecond range simultaneously with BSRS stimulated Brillouin scattering has been excited. Possible applications are discussed.

  7. Intravaginal artificial insemination in bitches using frozen/thawed semen after dilution in powdered coconut water (ACP-106c).

    PubMed

    Uchoa, D C; Silva, T F P; Mota Filho, A C; Silva, L D M

    2012-12-01

    The aim of this study was to evaluate powdered coconut water extender (ACP-106c; ACP Serviços Tecnológicos Ltda, ACP Biotecnologia, Fortaleza, Ceará, Brazil) as a diluent for freezing dog semen and the fertility after vaginal insemination of semen frozen therein. Ten ejaculates were collected from five dogs, evaluated fresh, diluted in ACP-106c, 10% egg yolk and 6% glycerol, cooled and frozen. In the first phase of the study, straws with frozen semen were thawed and immediately subjected to the same analysis as the fresh semen and, in addition, to Computer-Assisted Semen Analysis (CASA). In phase 2, 10 bitches that had been subjected to natural breeding during a preceding oestrous cycle were vaginally inseminated with thawed semen that had been re-diluted in ACP-106c. After thawing, a mean of 77% sperm motility was obtained through subjective analysis and 77.3% through CASA. Following artificial insemination, a 60% pregnancy rate was observed, resulting in a 50% parturition rate and a mean litter size of 3.4 (SEM 0.6), with 47.1% males and 52.9% females. ACP-106c can be successfully used for freezing canine semen, and vaginal deposition of such semen yields similar pregnancy rates to those reported in other studies.

  8. Na(+) and Ca(2+) pumps in the gills, epipodites and branchiostegites of the european lobster Homarus gammarus: effects of dilute sea water.

    PubMed

    Flik, G; Haond, C

    2000-01-01

    Crude homogenates and plasma-membrane-enriched fractions were prepared from the epithelium of the gills, epipodites and branchiostegites of intermoult European lobsters Homarus gammarus, and Na(+)/K(+)-ATPase, Ca(2+)-ATPase and Na(+)/Ca(2+) exchange activities were quantified in these tissues. Lobsters were kept in sea water (salinity 35 ) or were adapted to dilute sea water (22.1 ). The lobster hyperregulates haemolymph osmolarity and Ca(2+) levels in both media. Homogenates of the podobranchs, arthrobranchs and pleurobranchs had comparable Na(+)/K(+)-ATPase specific activities, and mean activities increased significantly for all three types of gills when the animals were kept in dilute sea water. In the epipodites and branchiostegites, Na(+)/K(+)-ATPase specific activities exceeded those in the gills, and exposure to dilute sea water greatly enhanced these activities. In sea water, 80 % of the total Na(+)/K(+)-ATPase activity is associated with the gills and epipodites (each tissue containing 40 %) and 20 % with the branchiostegites; in dilute sea water, the gills contained approximately 25 %, the epipodites 40 % and the branchiostegites approximately 35 % of the total activity, indicating the relative importance of the epipodites and branchiostegites for ionic hyperregulation in dilute media. In plasma membrane vesicles isolated from the gills, epipodites and branchiostegites, Ca(2+) transport driven by ATP and by a Na(+ )gradient was demonstrated. Exposure to dilute sea water enhanced Na(+)/Ca(2+ )exchange and Ca(2+)-ATPase activities in the epipodites and branchiostegites; in the gills, however, Ca(2+) transport activities decreased. The role of these tissues and enzymes in Na(+) and Ca(2+) handling by the lobster is discussed. PMID:10607531

  9. Effect of oxidation on the removal CU{sup 2+}, Cd{sup 2+} and Mn (VII) from dilute aqueous solutions by Upper Freeport bituminous coal. Quarterly report, June--August 1995

    SciTech Connect

    Bodine, D.L.

    1995-12-31

    Upper Freeport bituminous coal was able to remove Mn (VII) from dilute aqueous solution by concurrent adsorption and reduction of the manganese to lower valence, less toxic states. This type of reaction indicated the potential of using coal to remove oxidizing contaminants from effluents. Since oxidizing anions can degrade ion exchange resins and membranes, coal may be a viable alternative for detoxification. On analysis of the kinetics of copper and cadmium uptake from dilute aqueous solution, adsorption equilibria and functional groups analyses, it was apparent that the different oxidative pre-treatments affected both the surfaces and pore structure of Upper Freeport coal. The large amount of carboxyl and phenolic functional groups remaining after contact with copper and cadmium solutions, as determined by functional groups analyses, indicated the low affinity of the surface acid groups for these cations. Furthermore, there was almost no metal ion removal at low solution pH`s, which precludes the use of Upper Freeport for treating acidic wastes and effluents such as acid mine drainage. The coal surface functional groups are indeed able to exchange with cations, since the amount of these groups are measured by ion exchange with Na{sup +} and Ba{sup 2+}, however, it may be more difficult to displace the waters of hydration around Cu{sup 2+} and Cd{sup 2+}, to allow their uptake on the coal surface functional groups. Improved metal ion removal might be obtained using a lower rank coal, such as a subbituminous coal, which would be more susceptible to oxidation.

  10. Molecular properties and intermolecular forces--factors balancing the effect of carbon surface chemistry in adsorption of organics from dilute aqueous solutions.

    PubMed

    Terzyk, Artur P

    2004-07-01

    Presented paper recapitulates the results of 6 years' study concerning the effect of carbon surface chemical composition on adsorption of paracetamol, phenol, acetanilide, and aniline from dilute aqueous solutions on carbons. Adsorption-desorption isotherms, enthalpy, and kinetics of adsorption data are shown for the measurements performed at three temperatures (300, 310, and 320 K) at two pH levels (1.5 and 7) on commercial activated carbons. The data were obtained for four carbons: the initial carbon D43/1 and forms modified by applying concentrated HNO3, fuming H2SO4, and gaseous NH3. The modification procedures do not change the porosity in a drastic way, but lead to drastic changes of the composition of carbon surface layer. By applying MOPAC (a general-purpose semiempirical molecular orbital package), the physicochemical constants characterizing the molecules of adsorbates are calculated, including the distribution of the Mulliken charges, the dipole moments and ionization potentials, and the energies of interaction with the unique positive and negative charges. They are correlated with the parameters characterizing the adsorption (and kinetics) process of studied molecules on the mentioned above carbons. The mechanisms proposed in the literature for the description of adsorption from dilute aqueous solutions are verified, and a general mechanism of adsorption is proposed.

  11. Hierarchical amplification of macromolecular helicity of dynamic helical poly(phenylacetylene)s composed of chiral and achiral phenylacetylenes in dilute solution, liquid crystal, and two-dimensional crystal.

    PubMed

    Ohsawa, Sousuke; Sakurai, Shin-ichiro; Nagai, Kanji; Banno, Motonori; Maeda, Katsuhiro; Kumaki, Jiro; Yashima, Eiji

    2011-01-12

    Optically active poly(phenylacetylene) copolymers consisting of optically active and achiral phenylacetylenes bearing L-alanine decyl esters (1L) and 2-aminoisobutylic acid decyl esters (Aib) as the pendant groups (poly(1L(m)-co-Aib(n))) with various compositions were synthesized by the copolymerization of the optically active 1L with achiral Aib using a rhodium catalyst, and their chiral amplification of the macromolecular helicity in a dilute solution, a lyotropic liquid crystalline (LC) state, and a two-dimensional (2D) crystal on the substrate was investigated by measuring the circular dichroism of the copolymers, mesoscopic cholesteric twist in the LC state (cholesteric helical pitch), and high-resolution atomic force microscopy (AFM) images of the self-assembled 2D helix-bundles of the copolymer chains. We found that the macromolecular helicity of poly(1L(m)-co-Aib(n))s could be hierarchically amplified in the order of the dilute solution, LC state, and 2D crystal. In sharp contrast, almost no chiral amplification of the macromolecular helicity was observed for the homopolymer mixtures of 1L and Aib in the LC state and 2D crystal on graphite. PMID:21141965

  12. Earthworm effects on movement of water and solutes in soil

    SciTech Connect

    Trojan, M.D.

    1993-01-01

    The objectives of this study were to determine and model the effects of earthworms on water and solute movement in soil. Microrelief and rainfall effects on water and solute movement were determined in packed buckets inoculated with earthworms (Aporrectodea tuberculata). A solution of Br[sup [minus

  13. Determination of dilution factors for discharge of aluminum-containing wastes by public water-supply treatment facilities into lakes and reservoirs in Massachusetts

    USGS Publications Warehouse

    Colman, John A.; Massey, Andrew J.; Brandt, Sara L.

    2011-01-01

    In addition to computing dilution factors, the project determined dilution factors that would be protective with the same statistical basis (frequency of exceedence of the chronic standard) as dilutions computed for streams at the 7-day-average 10-year-recurrence annual low flow (the 7Q10). Low-flow dilutions are used for permitting so that receiving waters are protected even at the worst-case flow levels. The low-flow dilution factors that give the same statistical protection are the lowest annual 7-day-average dilution factors with a recurrence of 10 years, termed 7DF10s. Determination of 7DF10 values for reservoirs required that long periods of record be simulated so that dilution statistics could be determined. Dilution statistics were simulated for 13 reservoirs from 1960 to 2004 using U.S. Geological Survey Firm-Yield Estimator software to model reservoir inputs and outputs and present-day values of filter-effluent discharge and aluminum concentration. Computed settling velocities ranged from 0 centimeters per day (cm/d) at DOC concentrations of 15.5 milligrams per liter (mg/L) to 21.5 cm/d at DOC concentrations of 2.7 mg/L. The 7DF10 values were a function of aluminum effluent discharged. At current (2009) effluent discharge rates, the 7DF10 values varied from 1.8 to 115 among the 13 reservoirs. In most cases, the present-day (2009) discharge resulted in receiving water concentrations that did not exceed the standard at the 7DF10. Exceptions were one reservoir with a very small area and three reservoirs with high concentrations of DOC. Maximum permissible d

  14. In Silico Calculation of Infinite Dilution Activity Coefficients of Molecular Solutes in Ionic Liquids: Critical Review of Current Methods and New Models Based on Three Machine Learning Algorithms.

    PubMed

    Paduszyński, Kamil

    2016-08-22

    The aim of the paper is to address all the disadvantages of currently available models for calculating infinite dilution activity coefficients (γ(∞)) of molecular solutes in ionic liquids (ILs)-a relevant property from the point of view of many applications of ILs, particularly in separations. Three new models are proposed, each of them based on distinct machine learning algorithm: stepwise multiple linear regression (SWMLR), feed-forward artificial neural network (FFANN), and least-squares support vector machine (LSSVM). The models were established based on the most comprehensive γ(∞) data bank reported so far (>34 000 data points for 188 ILs and 128 solutes). Following the paper published previously [J. Chem. Inf. Model 2014, 54, 1311-1324], the ILs were treated in terms of group contributions, whereas the Abraham solvation parameters were used to quantify an impact of solute structure. Temperature is also included in the input data of the models so that they can be utilized to obtain temperature-dependent data and thus related thermodynamic functions. Both internal and external validation techniques were applied to assess the statistical significance and explanatory power of the final correlations. A comparative study of the overall performance of the investigated SWMLR/FFANN/LSSVM approaches is presented in terms of root-mean-square error and average absolute relative deviation between calculated and experimental γ(∞), evaluated for different families of ILs and solutes, as well as between calculated and experimental infinite dilution selectivity for separation problems benzene from n-hexane and thiophene from n-heptane. LSSVM is shown to be a method with the lowest values of both training and generalization errors. It is finally demonstrated that the established models exhibit an improved accuracy compared to the state-of-the-art model, namely, temperature-dependent group contribution linear solvation energy relationship, published in 2011 [J. Chem

  15. In Silico Calculation of Infinite Dilution Activity Coefficients of Molecular Solutes in Ionic Liquids: Critical Review of Current Methods and New Models Based on Three Machine Learning Algorithms.

    PubMed

    Paduszyński, Kamil

    2016-08-22

    The aim of the paper is to address all the disadvantages of currently available models for calculating infinite dilution activity coefficients (γ(∞)) of molecular solutes in ionic liquids (ILs)-a relevant property from the point of view of many applications of ILs, particularly in separations. Three new models are proposed, each of them based on distinct machine learning algorithm: stepwise multiple linear regression (SWMLR), feed-forward artificial neural network (FFANN), and least-squares support vector machine (LSSVM). The models were established based on the most comprehensive γ(∞) data bank reported so far (>34 000 data points for 188 ILs and 128 solutes). Following the paper published previously [J. Chem. Inf. Model 2014, 54, 1311-1324], the ILs were treated in terms of group contributions, whereas the Abraham solvation parameters were used to quantify an impact of solute structure. Temperature is also included in the input data of the models so that they can be utilized to obtain temperature-dependent data and thus related thermodynamic functions. Both internal and external validation techniques were applied to assess the statistical significance and explanatory power of the final correlations. A comparative study of the overall performance of the investigated SWMLR/FFANN/LSSVM approaches is presented in terms of root-mean-square error and average absolute relative deviation between calculated and experimental γ(∞), evaluated for different families of ILs and solutes, as well as between calculated and experimental infinite dilution selectivity for separation problems benzene from n-hexane and thiophene from n-heptane. LSSVM is shown to be a method with the lowest values of both training and generalization errors. It is finally demonstrated that the established models exhibit an improved accuracy compared to the state-of-the-art model, namely, temperature-dependent group contribution linear solvation energy relationship, published in 2011 [J. Chem

  16. Acidities of Water and Methanol in Aqueous Solution and DMSO

    ERIC Educational Resources Information Center

    Gao, Daqing

    2009-01-01

    The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent…

  17. Molecular level water and solute transport in reverse osmosis membranes

    NASA Astrophysics Data System (ADS)

    Lueptow, Richard M.; Shen, Meng; Keten, Sinan

    2015-11-01

    The water permeability and rejection characteristics of six solutes, methanol, ethanol, 2-propanol, urea, Na+, and Cl-, were studied for a polymeric reverse osmosis (RO) membrane using non-equilibrium molecular dynamics simulations. Results indicate that water flux increases with an increasing fraction of percolated free volume in the membrane polymer structure. Solute molecules display Brownian motion and hop from pore to pore as they pass through the membrane. The solute rejection depends on both the size of the solute molecule and the chemical interaction of the solute with water and the membrane. When the open spaces in the polymeric structure are such that solutes have to shed at least one water molecule from their solvation shell to pass through the membrane molecular structure, the water-solute pair interaction energy governs solute rejection. Organic solutes more easily shed water molecules than ions to more readily pass through the membrane. Hydrogen-bonding sites for molecules like urea also lead to a higher rejection. These findings underline the importance of the solute's solvation shell and solute-water-membrane chemistry in solute transport and rejection in RO membranes. Funded by the Institute for Sustainability and Energy at Northwestern with computing resources from XSEDE (NSF grant ACI-1053575).

  18. Niche for steam stripping in treating dilute SOC-contaminated waters

    SciTech Connect

    Dvorak, B.I.; Lawler, D.F.; Speitel, G.E. Jr.

    1996-09-01

    As regulatory limits for contaminants in air and water become increasingly stringent, interest in steam stripping to remove synthetic organic compounds (SOCs) from industrial waters has increased. To identify situations in which steam stripping could be a cost-competitive option for treating waters contaminated with low concentrations (<10 mg/L) of synthetic organic chemicals, the performance and cost of steam-stripping towers were modeled, and a range of hypothetical contaminated waters was examined. The cost of steam stripping was compared to that of air stripping, liquid-phase carbon adsorption, and air stripping with off-gas adsorption. Steam stripping was found to be a highly specialized treatment technology that will not frequently be cost-effective, but it does have a small niche in the environmental remediation market. Steam stripping is cost-effective when site-specific factors significantly reduce capital or operating costs, or when the target chemical is only marginally volatile, adsorbable, and biodegradable, effectively making all other conventional treatment methods more expensive.

  19. Modeling transport and dilution of produced water and the resulting uptake and biomagnification in marine biota

    SciTech Connect

    Rye, H.; Reed, M.; Slagstad, D.

    1996-12-31

    The paper explains the numerical modelling efforts undertaken in order to study possible marine biological impacts caused by releases of produced water from the Haltenbanken area outside the western coast of Norway. Acute effects on marine life from releases of produced water appear to be relatively small and confined to areas rather lose to the release site. Biomagnification may however be experienced for relatively low concentrations at larger distances from the release point. Such effects can he modeled by performing a step-wise approach which includes: The use of 3-D hydrodynamic models to determine the ocean current fields; The use of 3-D multi-source numerical models to determine the concentration fields from the produced water releases, given the current field; and The use of biologic models to simulate the behavior of and larvae (passive marine biota) and fish (active marine biota) and their interaction with the concentration field. The paper explains the experiences gained by using this approach for the calculation of possible influences on marine life below the EC{sub 50} or LC{sub 50} concentration levels. The models are used for simulating concentration fields from 5 simultaneous sources at the Haltenbank area and simulation of magnification in some marine species from 2 simultaneous sources in the same area. Naphthalenes and phenols, which are both present in the produced water, were used as the chemical substances in the simulations.

  20. Determination of atrazine, lindane, pentachlorophenol, and diazinon in water and soil by isotope dilution gas chromatography/mass spectrometry

    SciTech Connect

    Lopez-Avila, V.; Hirata, P.; Kraska, S.; Flanagan, M.; Taylor, J.H. Jr.; Hern, S.C.

    1985-12-01

    This paper describes an isotope dilution GC/MS technique for the analysis of low-parts-per-billion concentrations of atrazine, lindane, pentachlorophenol, and diazinon in water and soil. Known amounts of stable-labeled isotopes such as atrazine-d/sub 5/, lindane-d/sub 6/, pentachlorophenol-/sup 13/C/sub 6/, and diazinon-d/sub 10/ are spiked into each sample prior to extraction. Water samples are extracted with methylene chloride; soil samples are extracted with acetone/hexane. Analysis is performed by high-resolution GC/MS with the mass spectrometer operated in the selected ion monitoring mode. Accuracy greater than 86% and precision better than 8% were demonstrated by use of spiked samples. This technique has been used successfully in the analysis of over 300 water and 300 soil samples. Detection limits of 0.1-1.0 ppb were achieved for the test compounds by selected ion monitoring GC/MS. 8 references, 2 figures, 4 tables.

  1. Analytical solution for soil water redistribution during evaporation process.

    PubMed

    Teng, Jidong; Yasufuku, Noriyuki; Liu, Qiang; Liu, Shiyu

    2013-01-01

    Simulating the dynamics of soil water content and modeling soil water evaporation are critical for many environmental and agricultural strategies. The present study aims to develop an analytical solution to simulate soil water redistribution during the evaporation process. This analytical solution was derived utilizing an exponential function to describe the relation of hydraulic conductivity and water content on pressure head. The solution was obtained based on the initial condition of saturation and an exponential function to model the change of surface water content. Also, the evaporation experiments were conducted under a climate control apparatus to validate the theoretical development. Comparisons between the proposed analytical solution and experimental result are presented from the aspects of soil water redistribution, evaporative rate and cumulative evaporation. Their good agreement indicates that this analytical solution provides a reliable way to investigate the interaction of evaporation and soil water profile. PMID:24355839

  2. Dilution, Concentration, and Flotation

    ERIC Educational Resources Information Center

    Liang, Ling; Schmuckler, Joseph S.

    2004-01-01

    As both classroom teaching practice and literature show, many students have difficulties learning science concepts such as density. Here are some investigations that identify the relationship between density and floating through experimenting with successive dilution of a liquid, or the systematic change of concentration of a saltwater solution.…

  3. Separation of compounds with multiple -OH groups from dilute aqueous solutions via complexation with organoboronate. [1,2-propanediol

    SciTech Connect

    Chow, Tina Kuo Fung.

    1992-05-01

    The complexing extractant agent investigated in this work is 3-nitrophenylboronic acid (NPBA) in its anionic form (NPB). NPBA and Aliquat 336 (quaternary amine) is dissolved in 2-ethyl-l-hexanol, and the extractant is contacted with aq. NaOH. Solutes investigated were 1,2-propanediol, glycerol, fructose, sorbitol and lactic acid. Batch extraction experiments were performed at 25{degree}C. Partition coefficients, distribution ratios and loadings are reported for varying concentrations of solute and NPB. All solutes complexed with NPB{sup {minus}}, with all complexes containing only one NPB{sup {minus}} per complex. The 1:1 complexation constants for the solutes glycerol, fructose and sorbitol follow trends similar to complexation with B(OH){sub 4}{sup {minus}} (aq.), i.e. the complexation constants increase with increasing number of {minus}OH groups available for complexation. Assumption of 1:1 complex is not valid for 1, 2-propanediol, which showed overloading (more than one mole of solute complexed to one mole NPB{sup {minus}}) at higher concentrations. The {minus}OH group on the NPB{sup {minus}} which is left uncomplexed after one solute molecule had bound to the other two {minus}OH groups may be responsible for the overloading. Overloading is also observed in extraction of tactic acid, but through a different mechanism. It was found that TOMA{sup +} can extract lactic acid to an extent comparable to the uptake of lactic acid by NPB{sup {minus}}. The complexation is probably through formation of an acid-base ion pair. Losses of NPBA into the aqueous phase could lead to problems, poor economics in industrial separation processes. One way of overcoming this problem would be to incorporate the NPBA onto a solid support.

  4. Fundamental study on kinetics and transport phenomena in low water dilute acid total hydrolysis of cellulosic biomass

    SciTech Connect

    Auburn University

    2004-04-07

    The overall objective of this research is to delineate the process of the dilute-acid hydrolysis of biomass and seek better understanding of the reactions involving dilute-acid treatment of lignocellulosic biomass. Specifically the scope of the work entails the following two primary technical elements: Verification of the heterogeneous nature of the reaction mechanism in dilute-acid hydrolysis of cellulosic component of the biomass. Experimental investigation to identify the overall reaction pattern and the kinetic constants associated with dilute-acid hydrolysis of the cellulosic component of the agricultural residues.

  5. Effect of dilute polymer additives on the acoustic cavitation threshold of water

    SciTech Connect

    Crum, L.A.; Brosey, J.E.

    1984-02-01

    Measurements are presented of the variation of the acoustic cavitation threshold of water with concentration of the polymer additives polyethylene oxide and guar gum. It was found that small amounts of these additives could significantly increase the cavitation threshold. A theoretical model, based upon nucleation of a gas bubble from a Harvey-type crevice in a mote or solid particle, is developed that gives good agreement with the measurements. The applicability of this approach to an explanation of cavitation index reduction in flow-generated or confined jet cavitation, when polymer additives are introduced, is discussed.

  6. In vivo isotope-fractionation factors and the measurement of deuterium- and oxygen-18-dilution spaces from plasma, urine, saliva, respiratory water vapor, and carbon dioxide

    SciTech Connect

    Wong, W.W.; Cochran, W.J.; Klish, W.J.; Smith, E.O.; Lee, L.S.; Klein, P.D.

    1988-01-01

    In vivo isotope-fractionation factors were determined for hydrogen and oxygen between plasma water samples and samples of urine, saliva, respiratory water vapor, and carbon dioxide in 20 normal adults. The isotope-fractionation factors ranged from 0.944 to 1.039 for /sup 2/H in breath water vapor and for /sup 18/O in breath CO/sub 2/, respectively. When corrected for isotope fractionation, the /sup 2/H- and /sup 18/O-dilution spaces determined from urine, saliva, respiratory water, and CO/sub 2/ were within -0.10 +/- 1.09 kg (mean +/- SD, n = 60) and 0.04 +/- 0.68 kg (n = 80), respectively, of the values determined from plasma. In the absence of these corrections, we observed a 6% overestimation of /sup 2/H-dilution space and a 1% overestimation of /sup 18/O-dilution space from the use of respiratory water values. A 4% underestimation of the /sup 18/O-dilution space was observed for breath CO/sub 2/ without correction for isotope fractionation.

  7. Science Notes: Dilution of a Weak Acid

    ERIC Educational Resources Information Center

    Talbot, Christopher; Wai, Chooi Khee

    2014-01-01

    This "Science note" arose out of practical work involving the dilution of ethanoic acid, the measurement of the pH of the diluted solutions and calculation of the acid dissociation constant, K[subscript a], for each diluted solution. The students expected the calculated values of K[subscript a] to be constant but they found that the…

  8. Investigation of effects of background water on upwelled reflectance spectra and techniques for analysis of dilute primary-treated sewage sludge

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Usry, J. W.; Witte, W. G.; Farmer, F. H.; Gurganus, E. A.

    1979-01-01

    In an effort to improve understanding of the effects of variations in background water on reflectance spectra, laboratory tests were conducted with various concentrations of sewage sludge diluted with several types of background water. The results from these tests indicate that reflectance spectra for sewage-sludge mixtures are dependent upon the reflectance of the background water. Both the ratio of sewage-sludge reflectance to background-water reflectance and the ratio of the difference in reflectance to background-water reflectance show spectral variations for different turbid background waters. The difference in reflectance is the only parameter considered.

  9. Equilibrium water and solute uptake in silicone hydrogels.

    PubMed

    Liu, D E; Dursch, T J; Oh, Y; Bregante, D T; Chan, S Y; Radke, C J

    2015-05-01

    Equilibrium water content of and solute partitioning in silicone hydrogels (SiHys) are investigated using gravimetric analysis, fluorescence confocal laser-scanning microscopy (FCLSM), and back extraction with UV/Vis-absorption spectrophotometry. Synthesized silicone hydrogels consist of silicone monomer, hydrophilic monomer, cross-linking agent, and triblock-copolymer macromer used as an amphiphilic compatibilizer to prevent macrophase separation. In all cases, immiscibility of the silicone and hydrophilic polymers results in microphase-separated morphologies. To investigate solute uptake in each of the SiHy microphases, equilibrium partition coefficients are obtained for two hydrophilic solutes (i.e., theophylline and caffeine dissolved in aqueous phosphate-buffered saline) and two oleophilic solutes (i.e., Nile Red and Bodipy Green dissolved in silicone oil), respectively. Measured water contents and aqueous-solute partition coefficients increase linearly with increasing solvent-free hydrophilic-polymer volume fraction. Conversely, oleophilic-solute partition coefficients decrease linearly with rising solvent-free hydrophilic-polymer volume fraction (i.e., decreasing hydrophobic silicone-polymer fraction). We quantitatively predict equilibrium SiHy water and solute uptake assuming that water and aqueous solutes reside only in hydrophilic microdomains, whereas oleophilic solutes partition predominately into silicone microdomains. Predicted water contents and solute partition coefficients are in excellent agreement with experiment. Our new procedure permits a priori estimation of SiHy water contents and solute partition coefficients based solely on properties of silicone and hydrophilic homopolymer hydrogels, eliminating the need for further mixed-polymer-hydrogel experiments.

  10. Potential of mean force between two hydrophobic solutes in water.

    PubMed

    Southall, Noel T; Dill, Ken A

    2002-12-10

    We study the potential of mean force between two nonpolar solutes in the Mercedes Benz model of water. Using NPT Monte Carlo simulations, we find that the solute size determines the relative preference of two solute molecules to come into contact ('contact minimum') or to be separated by a single layer of water ('solvent-separated minimum'). Larger solutes more strongly prefer the contacting state, while smaller solutes have more tendency to become solvent-separated, particularly in cold water. The thermal driving forces oscillate with solute separation. Contacts are stabilized by entropy, whereas solvent-separated solute pairing is stabilized by enthalpy. The free energy of interaction for small solutes is well-approximated by scaled-particle theory.

  11. Potential of mean force between two hydrophobic solutes in water.

    PubMed

    Southall, Noel T; Dill, Ken A

    2002-12-10

    We study the potential of mean force between two nonpolar solutes in the Mercedes Benz model of water. Using NPT Monte Carlo simulations, we find that the solute size determines the relative preference of two solute molecules to come into contact ('contact minimum') or to be separated by a single layer of water ('solvent-separated minimum'). Larger solutes more strongly prefer the contacting state, while smaller solutes have more tendency to become solvent-separated, particularly in cold water. The thermal driving forces oscillate with solute separation. Contacts are stabilized by entropy, whereas solvent-separated solute pairing is stabilized by enthalpy. The free energy of interaction for small solutes is well-approximated by scaled-particle theory. PMID:12488009

  12. Formation of gold branched plates in diluted solutions of poly(vinylpyrrolidone) and their use for the fabrication of near-infrared-absorbing films and coatings.

    PubMed

    Pardiñas-Blanco, Iván; Hoppe, Cristina E; Piñeiro-Redondo, Yolanda; López-Quintela, M Arturo; Rivas, José

    2008-02-01

    Ribbon-like and branched gold nano- and microstructures were produced by simple heating of diluted aqueous solutions of poly(vinylpyrrolidone) (PVP) and HAuCl4. The reaction was carried out in a one-pot, one-step process at mild temperatures. Modification of the synthesis variables allowed the obtaining of structures with different sizes and branching degrees which formed stable hydrosols with characteristic colors. A mechanism for the growth of the crystals was proposed, based on the aggregation of metal units followed by reorientation and attachment processes facilitated by the presence of low concentrations of the polymer. These anisotropic structures were used to obtain large-area porous coatings on metallic, plastic, and glass substrates and to synthesize homogeneous polymer composites. The resulting gold-modified materials showed an important increase of absorption in the near-infrared (NIR) region of the electromagnetic spectrum, which could find interesting applications in the development of NIR-absorbing filters and coatings.

  13. Salt-induced transition from a micellar to a lamellar liquid crystalline phase in dilute mixtures of anionic and nonionic surfactants in aqueous solution

    SciTech Connect

    Sein, A.; Engberts, J.B.F.N. ); Linden, E. van der; Pas, J.C. van de )

    1993-07-01

    In dilute mixtures of anionic surfactant, sodium dodecylbenzenesulfonate (NaDoBS), and nonionic poly(ethylene oxide) alkylmonoether (C[sub 13-15]E[sub <7>]) a transition from a micellar to a lamellar phase is found at high salting-out electrolyte (NaCit) concentrations. With an increase of the salt concentration, different types of lamellar aggregates are formed. The existence of different types of aggregates is reflected by changes of the turbidity of the solutions. Light and fluorescence microscopy, freeze-fractured electron microscopy, confocal scanning laser microscopy (CSLM), and fluorescence depolarization were employed to characterize the aggregates and to induce a mechanism for the transition from a micellar to a lamellar phase. Surfactant aggregation is important in view of possible applications in enhanced oil recovery. 39 refs., 10 figs.

  14. A numerical study of the phase behaviors of drug particle/star triblock copolymer mixtures in dilute solutions for drug carrier application.

    PubMed

    Wang, Shanhui; Tong, Chaohui; Zhu, Yuejin

    2014-04-14

    The complex microstructures of drug particle/ABA star triblock copolymer in dilute solutions have been investigated by a theoretical approach which combines the self-consistent field theory and the hybrid particle-field theory. Simulation results reveal that, when the volume fraction of drug particles is smaller than the saturation concentration, the drug particle encapsulation efficiency is 100%, and micelle loading capacity increases with increasing particle volume fraction. When the volume fraction of drug particles is equal to the saturation concentration, the micelles attain the biggest size, and micelle loading capacity reaches a maximum value which is independent of the copolymer volume fraction. When the volume fraction of drug particles is more than the saturation concentration, drug particle encapsulation efficiency decreases with increasing volume fraction of drug particles. Furthermore, it is found that the saturation concentration scales linearly with the copolymer volume fraction. The above simulation results are in good agreement with experimental results.

  15. A numerical study of the phase behaviors of drug particle/star triblock copolymer mixtures in dilute solutions for drug carrier application

    SciTech Connect

    Wang, Shanhui; Tong, Chaohui; Zhu, Yuejin

    2014-04-14

    The complex microstructures of drug particle/ABA star triblock copolymer in dilute solutions have been investigated by a theoretical approach which combines the self-consistent field theory and the hybrid particle-field theory. Simulation results reveal that, when the volume fraction of drug particles is smaller than the saturation concentration, the drug particle encapsulation efficiency is 100%, and micelle loading capacity increases with increasing particle volume fraction. When the volume fraction of drug particles is equal to the saturation concentration, the micelles attain the biggest size, and micelle loading capacity reaches a maximum value which is independent of the copolymer volume fraction. When the volume fraction of drug particles is more than the saturation concentration, drug particle encapsulation efficiency decreases with increasing volume fraction of drug particles. Furthermore, it is found that the saturation concentration scales linearly with the copolymer volume fraction. The above simulation results are in good agreement with experimental results.

  16. Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions.

    PubMed

    Robotin, B; Ispas, A; Coman, V; Bund, A; Ilea, P

    2013-11-01

    This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model.

  17. Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions.

    PubMed

    Robotin, B; Ispas, A; Coman, V; Bund, A; Ilea, P

    2013-11-01

    This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model. PMID:23809618

  18. Characterization of the solvation environment provided by dilute aqueous solutions of novel siloxane polysoaps using the fluorescence probe pyrene.

    PubMed

    Pandey, Siddharth; Redden, Rebecca A; Hendricks, Ashley E; Fletcher, Kristin A; Palmer, Christopher P

    2003-06-15

    Solubilization environment afforded by several of the novel allyl glycidyl ether-modified methylhydrosiloxane polymers are investigated using a common polycyclic aromatic hydrocarbon fluorescence probe, pyrene. The backbone of the polymer has been modified by the addition of an alkyl chain of varying length (either C8, C12, or C18) and to differing degrees of substitution. The nomenclature adopted for the purposes of these studies is as follows: "AGENT" represents the backbone polymer with no alkyl substitution, and "OAGENT", "DAGENT", and "SAGENT" are substituted with n-octyl, n-dodecyl, and n-octadecyl, respectively. The percentage of alkyl substitution is designated as 10, 15, and 20%. The pyrene polarity scale (defined as the ratio of the intensity of peak I to peak III) was used to determine the relative dipolarity of the cybotactic region provided by approximately 1 w/w% aqueous polymer solutions compared to 10 mM sodium dodecylsulfate (SDS) micellar solution. Results indicate that 10-15% DAGENT afforded the most hydrophobic solubilization site, followed by 15% OAGENT and 15% SAGENT. In addition, as the degree of alkyl substitution of DAGENT increased from 10 to 20%, the cybotactic region appeared to become more hydrophobic. Furthermore, a deeper investigation into the relative size of the solubilization site revealed that all alkyl-substituted polymers promoted excimer formation at relatively low pyrene concentrations, indicating the possibility of localized concentration enhancement within the solvation pockets and/or compartmentalization of the solute molecules. The pyrene fluorescence excitation data strongly indicates ground-state heterogeneity that is most prominent in AGENT and decreases as the alkyl chain length is increased. This provides a relative sense of the size and shape of the solvation pockets afforded by each polymer solution. An overall analysis of the collected data indicated that these alkyl-substituted polymers may provide a more

  19. Dispersion serial dilution methods using the gradient diluter device.

    PubMed

    Walling, Leslie; Schulz, Craig; Johnson, Michael

    2012-12-01

    A solute aspirated into a prefilled tube of diluent undergoes a dilution effect known as dispersion. Traditionally the effects of dispersion have been considered a negative consequence of using liquid-filled fixed-tip liquid handlers. We present a novel device and technique that utilizes the effects of dispersion to the benefit of making dilutions. The device known as the Gradient Diluter extends the dilution range of practical serial dilutions to six orders of magnitude in final volumes as low as 10 μL. Presented are the device, dispersion methods, and validation tests using fluorescence detection of sulforhodamine and the high-performance liquid chromatography/ultraviolet detection of furosemide. In addition, a T-cell inhibition assay of a relevant downstream protein is used to demonstrate IC(50) curves made with the Gradient Diluter compare favorably with those generated by hand.

  20. Significantly improving enzymatic saccharification of high crystallinity index's corn stover by combining ionic liquid [Bmim]Cl-HCl-water media with dilute NaOH pretreatment.

    PubMed

    He, Yu-Cai; Liu, Feng; Gong, Lei; Zhu, Zheng-Zhong; Ding, Yun; Wang, Cheng; Xue, Yu-Feng; Rui, Huan; Tao, Zhi-Cheng; Zhang, Dan-Ping; Ma, Cui-Luan

    2015-01-01

    In this study, a pretreatment by combining acidified aqueous ionic liquid 1-butyl-3-methylimidazolium chloride (IL [Bmim]Cl) solution with dilute NaOH extraction was employed to pretreat high crystallinity index (CrI) of corn stover before its enzymatic saccharification. After NaOH extraction, [Bmim]Cl-HCl-water (78.8:1.2:20, w/w/w) media was used for further pretreatment at 130 °C for 30 min. After being enzymatically hydrolyzed for 48 h, corn stover pretreated could be biotransformed into reducing sugars in the yield of 95.1%. Furthermore, SEM, XRD and FTIR analyses of untreated and pretreated corn stovers were examined. It was found that the intact structure was disrupted by combination pretreatment and resulted in a porous and amorphous regenerated cellulosic material that greatly improved enzymatic hydrolysis. Finally, the recovered hydrolyzates obtained from the enzymatic hydrolysis of pretreated corn stovers could be fermented into ethanol efficiently. In conclusion, the combination pretreatment shows high potential application in future.

  1. An approach by using near-infrared diffuse reflectance spectroscopy and resin adsorption for the determination of copper, cobalt and nickel ions in dilute solution.

    PubMed

    Sheng, Nan; Cai, Wensheng; Shao, Xueguang

    2009-07-15

    Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it is seldom, however, used in the analysis of metal ions in solutions. A method for quantitative determination of metal ions in solution is developed by using resin adsorption and near-infrared diffuse reflectance spectroscopy (NIRDRS). The method makes use of the resin adsorption for gathering the analytes from a dilute solution, and then NIRDRS of the adsorbate is measured. Because both the information of the metal ions and their interaction with the functional group of resin can be reflected in the spectrum, quantitative determination is achieved by using multivariate calibration technique. Taking copper (Cu(2+)), cobalt (Co(2+)) and nickel (Ni(2+)) as the analyzing targets and D401 resin as the adsorbent, partial least squares (PLS) model is built from the NIRDRS of the adsorbates. The results show that the concentrations that can be quantitatively detected are as low as 1.00, 1.98 and 1.00 mg L(-1) for Cu(2+), Co(2+) and Ni(2+), respectively, and the coexistent ions do not influence the determination.

  2. NASA's Water Solutions Using Remote Sensing

    NASA Technical Reports Server (NTRS)

    Toll, David

    2012-01-01

    NASA Water Resources works within Earth sciences to leverage investments of space-based observation, model results, and development and deployment of enabling technologies, systems, and capabilities into water resources management decision support tools for the sustainable use of water. Earth science satellite observations and modelling products provide a huge volume of valuable data in both near-real-time and extended back nearly 50 years about the Earth's land surface conditions such as land cover type, vegetation type and health, precipitation, snow, soil moisture, and water levels and radiation. Observations of this type combined with models and analysis enable satellite-based assessment of the water cycle. With increasing population pressure and water usage coupled with climate variability and change, water issues are being reported by numerous groups as the most critical environmental problems facing us in the 21st century. Competitive uses and the prevalence of river basins and aquifers that extend across boundaries engender political tensions between communities, stakeholders and countries. The NASA Water Resources Program has the objective to provide NASA products to help deal with these issues with the goal for the sustainable use of water. The Water Resources program organizes its projects under five functional themes: 1) stream-flow and flood forecasting; 2) water consumptive use (includes evapotranspiration) and irrigation; 3) drought; 4) water quality; and 5) climate and water resources. NASA primarily works with national and international groups such as other US government agencies (NOAA, EPA, USGS, USAID) and various other groups to maximize the widest use of the water products. A summary of NASA's water activities linked to helping solve issues for developing countries will be highlighted.

  3. Ions in water: The microscopic structure of concentrated hydroxide solutions

    NASA Astrophysics Data System (ADS)

    Imberti, S.; Botti, A.; Bruni, F.; Cappa, G.; Ricci, M. A.; Soper, A. K.

    2005-05-01

    Neutron-diffraction data on aqueous solutions of hydroxides, at solute concentrations ranging from 1 solute per 12 water molecules to 1 solute per 3 water molecules, are analyzed by means of a Monte Carlo simulation (empirical potential structure refinement), in order to determine the hydration shell of the OH- in the presence of the smaller alkali metal ions. It is demonstrated that the symmetry argument between H+ and OH- cannot be used, at least in the liquid phase at such high concentrations, for determining the hydroxide hydration shell. Water molecules in the hydration shell of K+ orient their dipole moment at about 45° from the K+-water oxygen director, instead of radially as in the case of the Li+ and Na+ hydration shells. The K+-water oxygen radial distribution function shows a shallower first minimum compared to the other cation-water oxygen functions. The influence of the solutes on the water-water radial distribution functions is shown to have an effect on the water structure equivalent to an increase in the pressure of the water, depending on both ion concentration and ionic radius. The changes of the water structure in the presence of charged solutes and the differences among the hydration shells of the different cations are used to present a qualitative explanation of the observed cation mobility.

  4. Ions in water: the microscopic structure of concentrated hydroxide solutions.

    PubMed

    Imberti, S; Botti, A; Bruni, F; Cappa, G; Ricci, M A; Soper, A K

    2005-05-15

    Neutron-diffraction data on aqueous solutions of hydroxides, at solute concentrations ranging from 1 solute per 12 water molecules to 1 solute per 3 water molecules, are analyzed by means of a Monte Carlo simulation (empirical potential structure refinement), in order to determine the hydration shell of the OH- in the presence of the smaller alkali metal ions. It is demonstrated that the symmetry argument between H+ and OH- cannot be used, at least in the liquid phase at such high concentrations, for determining the hydroxide hydration shell. Water molecules in the hydration shell of K+ orient their dipole moment at about 45 degrees from the K+-water oxygen director, instead of radially as in the case of the Li+ and Na+ hydration shells. The K+-water oxygen radial distribution function shows a shallower first minimum compared to the other cation-water oxygen functions. The influence of the solutes on the water-water radial distribution functions is shown to have an effect on the water structure equivalent to an increase in the pressure of the water, depending on both ion concentration and ionic radius. The changes of the water structure in the presence of charged solutes and the differences among the hydration shells of the different cations are used to present a qualitative explanation of the observed cation mobility.

  5. Treatment for hydrazine-containing waste water solution

    NASA Technical Reports Server (NTRS)

    Yade, N.

    1986-01-01

    The treatment for waste solutions containing hydrazine is presented. The invention attempts oxidation and decomposition of hydrazine in waste water in a simple and effective processing. The method adds activated charcoal to waste solutions containing hydrazine while maintaining a pH value higher than 8, and adding iron salts if necessary. Then, the solution is aerated.

  6. Statistical mechanics of sum frequency generation spectroscopy for the liquid-vapor interface of dilute aqueous salt solutions

    SciTech Connect

    Noah-Vanhoucke, Joyce; Smith, Jared D.; Geissler, Phillip L.

    2009-01-02

    We demonstrate a theoretical description of vibrational sum frequency generation (SFG) at the boundary of aqueous electrolyte solutions. This approach identifies and exploits a simple relationship between SFG lineshapes and the statistics of molecular orientation and electric field. Our computer simulations indicate that orientational averages governing SFG susceptibility do not manifest ion-specific shifts in local electric field, but instead, ion-induced polarization of subsurface layers. Counterbalancing effects are obtained for monovalent anions and cations at the same depth. Ions held at different depths induce an imbalanced polarization, suggesting that ion-specific effects can arise from weak, long ranged influence on solvent organization.

  7. Impact of water dilution and cation tail length on ionic liquid characteristics: Interplay between polar and non-polar interactions

    NASA Astrophysics Data System (ADS)

    Hegde, Govind A.; Bharadwaj, Vivek S.; Kinsinger, Corey L.; Schutt, Timothy C.; Pisierra, Nichole R.; Maupin, C. Mark

    2016-08-01

    The recalcitrance of lignocellulosic biomass poses a major challenge that hinders the economical utilization of biomass for the production of biofuel, plastics, and chemicals. Ionic liquids have become a promising solvent that addresses many issues in both the pretreatment process and the hydrolysis of the glycosidic bond for the deconstruction of cellulosic materials. However, to make the use of ionic liquids economically viable, either the cost of ionic liquids must be reduced, or a less expensive solvent (e.g., water) may be added to reduce the overall amount of ionic liquid used in addition to reducing the viscosity of the binary liquid mixture. In this work, we employ atomistic molecular dynamics simulations to investigate the impact of water dilution on the overall liquid structure and properties of three imidazolium based ionic liquids. It is found that ionic liquid-water mixtures exhibit characteristics that can be grouped into two distinct regions, which are a function of the ionic liquid concentration. The trends observed in each region are found to correlate with the ordering in the local structure of the ionic liquid that arises from the dynamic interactions between the ion pairs. Simulation results suggest that there is a high level of local ordering in the molecular structure at high concentrations of ionic liquids that is driven by the aggregation of the cationic tails and the anion-water interactions. It is found that as the concentration of ionic liquids in the binary mixture is decreased, there is a point at which the competing self and cross interaction energies between the ionic liquid and water shifts away from a cation-anion dominated regime, which results in a significant change in the mixture properties. This break point, which occurs around 75% w/w ionic liquids, corresponds to the point at which water molecules percolate into the ionic liquid network disrupting the ionic liquids' nanostructure. It is observed that as the cationic alkyl

  8. Kinetics and mechanisms of the conversion of silicate (45S5), borate, and borosilicate glasses to hydroxyapatite in dilute phosphate solutions.

    PubMed

    Huang, Wenhai; Day, Delbert E; Kittiratanapiboon, Kanisa; Rahaman, Mohamed N

    2006-07-01

    Bioactive glasses with controllable conversion rates to hydroxyapatite (HA) may provide a novel class of scaffold materials for bone tissue engineering. The objective of the present work was to comprehensively characterize the conversion of a silicate bioactive glass (45S5), a borate glass, and two intermediate borosilicate glass compositions to HA in a dilute phosphate solution at 37 degrees Celsius. The borate glass and the borosilicate glasses were derived from the 45S5 glass by fully or partially replacing the SiO(2) with B(2)O(3). Higher B(2)O(3) content produced a more rapid conversion of the glass to HA and a lower pH value of the phosphate solution. Whereas the borate glass was fully converted to HA in less than 4 days, the silicate (45S5) and borosilicate compositions were only partially converted even after 70 days, and contained residual SiO(2) in a Na-depleted core. The concentration of Na(+) in the phosphate solution increased with reaction time whereas the PO(4) (3-) concentration decreased, both reaching final limiting values at a rate that increased with the B(2)O(3) content of the glass. However, the Ca(2+) concentration in the solution remained low, below the detection limit of atomic absorption, throughout the reaction. Immersion of the glasses in a mixed solution of K(2)HPO(4) and K(2)CO(3) produced a carbonate-substituted HA but the presence of the K(2)CO(3) had little effect on the kinetics of conversion to HA. The kinetics and mechanisms of the conversion process of the four glasses to HA are compared and used to develop a model for the process.

  9. Extraction and concentration of organic solutes from water

    USGS Publications Warehouse

    Goldberg, M.C.; DeLong, L.; Sinclair, M.

    1973-01-01

    A continuous extraction apparatus is described. It extracts and simultaneously concentrates organic solutes from water. Any immiscible solvent can be used in this apparatus if the solute will partition between the solvent and water. A concentration factor of up to 105 is obtained with this technique. The dipole moment difference between the solute and solvent is demonstrated to be an index of the extraction efficiency. Optimum extraction of a given molecular species may be obtained by use of this index.

  10. Nickel recovery from electronic waste II Electrodeposition of Ni and Ni–Fe alloys from diluted sulfate solutions

    SciTech Connect

    Robotin, B.; Ispas, A.; Coman, V.; Bund, A.; Ilea, P.

    2013-11-15

    Highlights: • Ni can be recovered from EG wastes as pure Ni or as Ni–Fe alloys. • The control of the experimental conditions gives a certain alloy composition. • Unusual deposits morphology shows different nucleation mechanisms for Ni vs Fe. • The nucleation mechanism was progressive for Ni and instantaneous for Fe and Ni–Fe. - Abstract: This study focuses on the electrodeposition of Ni and Ni–Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni{sup 2+}/Fe{sup 2+} ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits’ thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni–Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni–Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni–Fe, the obtained data points are best fitted to an instantaneous nucleation model.

  11. Correlation of biological value of feed phosphates with their solubility in water, dilute hydrogen chloride, dilute citric acid, and neutral ammonium citrate.

    PubMed

    Sullivan, T W; Douglas, J H; Gonzalez, N J; Bond, P L

    1992-12-01

    Relative biological values (BV) of 36 feed phosphates were determined with female turkeys in bioassays of 21-day duration using three response criteria: weight gain, tibia ash percentage, and gain:feed ratio. Calcium phosphate, dibasic dihydrate (United States Pharmacopeia) was the reference standard. Nine mono-dicalcium phosphates (M-DCP, 21.0% phosphorus), 13 di-monocalcium phosphates (D-MCP, 18.5% phosphorus), and 14 defluorinated phosphates (DFP, 18.0% phosphorus) were evaluated. The average relative BV for M-DCP, D-MCP, and DFP samples were 97.6, 94.6, and 90.8%, respectively. Solubility of phosphates was determined by four recognized methods. The solvents were water, .4% HCl, 2.0% citric acid (CA), and neutral ammonium citrate (NAC). Water solubility of M-DCP samples was greater (67.5%) than that of D-MCP (38.8%) and DFP (8.9%) samples. Correlation of water solubility of phosphates to their relative BV was quite low, and water solubility was a poor indicator of BV. When .4% HCl was the solvent, correlation coefficients (r) were .55, .33, and .72 for M-DCP, D-MCP, and DFP, respectively. Based on these results and prediction equations, .4% HCl solubility would be inappropriate for estimating BV of M-DCP and D-MCP samples. Solubility of feed phosphates (mainly D-MCP and DFP) in 2.0% CA or NAC was positively correlated with BV; the r values were .87 to .95. Both of these solubility tests provided a good index of BV. However, it would seem inappropriate and risky to replace bioassays totally with these tests. Feed phosphate users could perform either the 2.0% CA or NAC solubility test easily as a screen for BV along with other quality control procedures (i.e., phosphorus, calcium, sodium, and fluoride determinations).

  12. Measurement of total body water in human infants using deuterium isotope dilution and nuclear magnetic resonance spectroscopy

    SciTech Connect

    Rebouche, C.J.; Pearson, G.A.; Serfass, R.E.; Roth, C.W.; Finley, J.W.

    1986-03-01

    Total body water (TBW) provides a useful measure of fat-free body mass. Deuterium (D) oxide isotope dilution is a useful method to determine TBW. Various techniques, including density, infrared absorption, mass spectrometry and gas chromatography have been employed to determine D enrichment in body fluids. Each of these methods requires extensive sample preparation (sublimation or distillation of the body fluid). The authors have employed nuclear magnetic resonance (NMR) spectroscopy to measure D enrichment in saliva and urine of human infants. No sample preparation was necessary. A standard (dg-t-butanol) was added to 0.5 ml of sample and D enrichment was measured using a JEOL FX-900 NMR spectrometer. Signal acquisition time was 4.7 min. Working range of D enrichment was 0.04-0.32 atom % D (corresponding to an oral dose of approximately 0.25-2.0 g D/sub 2/O/kg body weight). Coefficients of variation (c.v.) for saliva samples at 0.20 and 0.06 atom % enrichment were 1.97% and 4.78%, respectively. Mean (+/-SD) of TBW determinations for 6 infants was 58.5 +/- 5.4% of body weight (range 53-66%). Repeat measurements (3) of TBW for each infant at weekly intervals yielded a mean c.v. of 4.1% (n = 6). This method provides precise measurement of TBW without the extensive sample preparation requirements of previously-described methods.

  13. Saline solutions: the quest for fresh water.

    PubMed

    Reuther, C G

    2000-02-01

    Despite steady advances in the technology, desalination remains one of the most expensive ways to produce potable water. But as water scarcity forces communities to find new sources of drinking water, scientists are developing innovations that may soon make desalination a reasonable option for many more communities. The newest approach to desalination is membrane systems, which include reverse osmosis and electrodialysis systems. Current research seeks to make these systems more effective and less likely to produce environmentally hazardous by-products. Many facilities use traditional distillation to desalinate water, and efforts are being made to combine membranes and distillation for more efficient systems.

  14. Saline solutions: the quest for fresh water.

    PubMed Central

    Reuther, C G

    2000-01-01

    Despite steady advances in the technology, desalination remains one of the most expensive ways to produce potable water. But as water scarcity forces communities to find new sources of drinking water, scientists are developing innovations that may soon make desalination a reasonable option for many more communities. The newest approach to desalination is membrane systems, which include reverse osmosis and electrodialysis systems. Current research seeks to make these systems more effective and less likely to produce environmentally hazardous by-products. Many facilities use traditional distillation to desalinate water, and efforts are being made to combine membranes and distillation for more efficient systems. PMID:10656867

  15. Different behavior of water in confined solutions of high and low solute concentrations.

    PubMed

    Elamin, Khalid; Jansson, Helén; Kittaka, Shigeharu; Swenson, Jan

    2013-11-14

    Water-glycerol solutions confined in 21 Å pores of the silica matrix MCM-41 C10 have been studied using differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The results suggest a micro-phase separation caused by the confinement. Likely the water molecules coordinate to the hydroxyl surface groups of the pores, leaving most of the glycerol molecules in the centre of the pores. This makes the dynamics of glycerol almost concentration independent up to water concentrations of about 85 wt%. However, at higher water concentrations no substantial clustering of glycerol molecules should occur and the glass transition related dynamics exhibit an anomalous behaviour. Instead of a common plasticization effect of water, as for the corresponding bulk solutions (when no ice is formed), it is evident that water acts as an anti-plasticizer in the confinement at high water concentrations. We propose that the increased water concentration slows down the glass transition related dynamics in the deeply supercooled regime due to that a rigid hydrogen bonded network structure of water molecules is formed at low temperatures and low glycerol concentrations. This is in contrast to the situation in a homogenously mixed bulk solution of a high solute concentration where the water molecules will be less hydrogen bonded, and therefore are typically more mobile than the surrounding solute molecules. An almost complete hydrogen bonded network of water molecules may, even in confinements, be sufficiently rigid to slow down the relaxation of embedded solute molecules. It can also be expressed the other way around, i.e. small amounts of glycerol act as a plasticizer for water, due to its breaking up of the nearly tetrahedral network structure. From the here observed concentration dependent behaviour of the deeply supercooled bulk and confined solutions it seems, furthermore, evident that the Tg value of bulk water cannot be estimated from extrapolations of aqueous

  16. Various contributions to the osmotic second virial coefficient in protein-water-cosolvent solutions.

    PubMed

    Shulgin, Ivan L; Ruckenstein, Eli

    2008-11-20

    An analysis of the cosolvent concentration dependence of the osmotic second virial coefficient (OSVC) in water-protein-cosolvent mixtures is developed. The Kirkwood-Buff fluctuation theory for ternary mixtures is used as the main theoretical tool. On its basis, the OSVC is expressed in terms of the thermodynamic properties of infinitely dilute (with respect to the protein) water-protein-cosolvent mixtures. These properties can be divided into two groups: (1) those of infinitely dilute protein solutions (such as the partial molar volume of a protein at infinite dilution and the derivatives of the protein activity coefficient with respect to the protein and water molar fractions) and (2) those of the protein-free water-cosolvent mixture (such as its concentrations, the isothermal compressibility, the partial molar volumes, and the derivative of the water activity coefficient with respect to the water molar fraction). Expressions are derived for the OSVC of ideal mixtures and for a mixture in which only the binary mixed solvent is ideal. The latter expression contains three contributions: (1) one due to the protein-solvent interactions B2(p-s), which is connected to the preferential binding parameter, (2) another one due to protein/protein interactions (B2(p-p)), and (3) a third one representing an ideal mixture contribution (B2(id)). The cosolvent composition dependencies of these three contributions were examined for several water-protein-cosolvent mixtures using experimental data regarding the OSVC and the preferential binding parameter. For the water-lysozyme-arginine mixture, it was found that OSVC exhibits the behavior of an ideal mixture and that B2(id) provides the main contribution to the OSVC. For the other mixtures considered (water-Hm MalDH-NaCl, water-Hm MalDH-(NH4)2SO4, and water-lysozyme-NaCl mixtures), it was found that the contribution of the protein-solvent interactions B2(p-s) is responsible for the composition dependence of the OSVC on the

  17. Development of robotic analysis for input solution sample by ion-exchange separation and isotope dilution method

    SciTech Connect

    Uchikoshi, S.; Ishikawa, M.; Kato, Y.; Ito, M.; Adachi, T.

    1993-12-31

    An automated analytical system for input solution samples has been developed to increase analytical capability and to improve timeliness of measurements in a future large scale reprocessing plant. The original automated analytical system for input solution samples was composed of three subsystems for sample preparation together with a mass spectrometer and an alpha-ray spectrometer. This system was modified to meet the specifications for a large scale reprocessing plant and for the practical use of LSD (Large Size Dry) spike in input analysis. By adding the functions of subsystem 2 (ion-exchange separation) to the original subsystem 1, the latter was modified to work from sample aliquoting to ion-exchange separation. The components included in the modified subsystem 1+2 are contained in an envelope the size of the original subsystem 1. This was accomplished by miniaturizing the equipment and making the preparation procedures more effective. The subsystems basically consist of Cartesian robots with other necessary components. In subsystem 1+2, small duplicate samples are placed into two beakers, one of which contains an LSD spike. The valency state of plutonium in the samples is subsequently adjusted to be tetravalent. Uranium in the samples is then separated from the plutonium by an anion exchange separation technique. In subsystem 3, a small quantity of each separated fraction is placed on a mass spectrometer filament by a loading device where the fraction is automatically dried. In addition, a small quantity of the plutonium fraction is deposited on a counting dish for alpha-ray spectrometry. Using precisely known amounts of uranium and plutonium mixtures, the analytical results for concentrations of both elements obtained by this system exhibited 0.4 to 0.6% in both precision and accuracy. After modification, the time required for sample preparation was shortened from 18 to 10 hours.

  18. Viruses in Water: The Problem, Some Solutions

    ERIC Educational Resources Information Center

    Gerba, Charles P.; And Others

    1975-01-01

    Increasing population and industrialization places heavy demands on water resources making recycling of wastewaters for domestic consumption inevitable. Eliminating human pathogenic viruses is a major problem of reclaiming wastewater. Present water treatment methods may not be sufficient to remove viruses. (MR)

  19. Analysis of the onset of elastic instabilities in a homogenous stagnation point flow using dilute polymer solutions

    NASA Astrophysics Data System (ADS)

    Cruz, Filipe; Haward, Simon; Alves, Manuel; McKinley, Gareth

    2014-11-01

    We compare numerical and experimental results for viscoelastic flows in the optimized cross-slot extensional rheometer - OSCER (Haward et al., Phys. Rev. Lett. 109, 128301, 2012) up to the onset of elastically-driven flow instabilities. Model polymer solutions with almost constant shear viscosity are used in the experiments, and the FENE-CR constitutive model is used in the 2D numerical simulations together with an in-house finite-volume viscoelastic flow solver. We match the model parameters to the rheology of the fluids used in the experiments, and the simulations are conducted for a wide range of flow rates, ranging from Newtonian-like flow at low Weissenberg numbers (Wi) up to the onset of time-dependent elastic instabilities at high Wi. We test the applicability of a dimensionless stability criterion (McKinley et al., J Non-Newt Fluid Mech. 67, 19, 1996) for predicting the onset of flow instability for both the experimental and computational data sets, using a spatially-resolved procedure to locally compute the stability criterion in the vicinity of the stagnation point. By evaluating this dimensionless criterion on a pointwise basis we are able to clearly distinguish the OSCER flow geometry from the archetypal cross-slot geometry.

  20. Improved prediction of octanol-water partition coefficients from liquid-solute water solubilities and molar volumes

    USGS Publications Warehouse

    Chiou, C.T.; Schmedding, D.W.; Manes, M.

    2005-01-01

    A volume-fraction-based solvent-water partition model for dilute solutes, in which the partition coefficient shows a dependence on solute molar volume (V??), is adapted to predict the octanol-water partition coefficient (K ow) from the liquid or supercooled-liquid solute water solubility (Sw), or vice versa. The established correlation is tested for a wide range of industrial compounds and pesticides (e.g., halogenated aliphatic hydrocarbons, alkylbenzenes, halogenated benzenes, ethers, esters, PAHs, PCBs, organochlorines, organophosphates, carbamates, and amidesureas-triazines), which comprise a total of 215 test compounds spanning about 10 orders of magnitude in Sw and 8.5 orders of magnitude in Kow. Except for phenols and alcohols, which require special considerations of the Kow data, the correlation predicts the Kow within 0.1 log units for most compounds, much independent of the compound type or the magnitude in K ow. With reliable Sw and V data for compounds of interest, the correlation provides an effective means for either predicting the unavailable log Kow values or verifying the reliability of the reported log Kow data. ?? 2005 American Chemical Society.

  1. Adsorption of Selected Pharmaceutical Compounds onto Activated Carbon in Dilute Aqueous Solutions Exemplified by Acetaminophen, Diclofenac, and Sulfamethoxazole

    PubMed Central

    Chang, E.-E.; Wan, Jan-Chi; Liang, Chung-Huei; Dai, Yung-Dun; Chiang, Pen-Chi

    2015-01-01

    The adsorption of three pharmaceuticals, namely, acetaminophen, diclofenac, and sulfamethoxazole onto granular activated carbon (GAC), was investigated. To study competitive adsorption, both dynamic and steady-state adsorption experiments were conducted by careful selection of pharmaceuticals with various affinities and molecular size. The effective diffusion coefficient of the adsorbate was increased with decease in particle size of GAC. The adsorption affinity represented as Langmuir was consistent with the ranking of the octanol-water partition coefficient, Kow. The adsorption behavior in binary or tertiary systems could be described by competition adsorption. In the binary system adsorption replacement occurred, under which the adsorbate with the smaller Kow was replaced by the one with larger Kow. Results also indicated that portion of the micropores could be occupied only by the small target compound, but not the larger adsorbates. In multiple-component systems the competition adsorption might significantly be affected by the macropores and less by the meso- or micropores. PMID:26078989

  2. A key parameter on the adsorption of diluted aniline solutions with activated carbons: The surface oxygen content.

    PubMed

    Pardo, Beatrice; Ferrer, Nabí; Sempere, Julià; Gonzalez-Olmos, Rafael

    2016-11-01

    A total of 11 different commercial activated carbons (AC) with well characterized textural properties and oxygen surface content were tested as adsorbents for the removal of aniline as a target water pollutant. The maximum adsorption capacity of aniline for the studied AC was from 138.9 to 257.9 mg g(-1) at 296.15 K and it was observed to be strongly related to the textural properties of the AC, mainly with the BET surface area and the micropore volume. It was not observed any influence of the oxygen surface content of the AC on the maximum adsorption capacity. However, it was found that at low aniline aqueous concentration, the presence of oxygen surface groups plays a dominant role during the adsorption. A high concentration of oxygen surface groups, mainly carboxylic and phenolic groups, decreases the aniline adsorption regardless of the surface area of the AC. PMID:27497348

  3. A key parameter on the adsorption of diluted aniline solutions with activated carbons: The surface oxygen content.

    PubMed

    Pardo, Beatrice; Ferrer, Nabí; Sempere, Julià; Gonzalez-Olmos, Rafael

    2016-11-01

    A total of 11 different commercial activated carbons (AC) with well characterized textural properties and oxygen surface content were tested as adsorbents for the removal of aniline as a target water pollutant. The maximum adsorption capacity of aniline for the studied AC was from 138.9 to 257.9 mg g(-1) at 296.15 K and it was observed to be strongly related to the textural properties of the AC, mainly with the BET surface area and the micropore volume. It was not observed any influence of the oxygen surface content of the AC on the maximum adsorption capacity. However, it was found that at low aniline aqueous concentration, the presence of oxygen surface groups plays a dominant role during the adsorption. A high concentration of oxygen surface groups, mainly carboxylic and phenolic groups, decreases the aniline adsorption regardless of the surface area of the AC.

  4. WATER CONSERVATION: LOCAL SOLUTIONS TO A GLOBAL PROBLEM

    EPA Science Inventory

    Water conservation issues are discussed. Local solutions to a global problem include changing old habits relating to the usage and abuse of water resources. While the suggested behavioral changes may not solve the world's pending water crisis, they may ease the impact of the l...

  5. Influence of surfactants on unsaturated water flow and solute transport

    NASA Astrophysics Data System (ADS)

    Karagunduz, Ahmet; Young, Michael H.; Pennell, Kurt D.

    2015-04-01

    Surfactants can reduce soil water retention by changing the surface tension of water and the contact angle between the liquid and solid phases. As a result, water flow and solute transport in unsaturated soil may be altered in the presence of surfactants. In this study, the effects of a representative nonionic surfactant, Triton X-100, on coupled water flow and nonreactive solute transport during unsaturated flow conditions were evaluated. Batch reactor experiments were conducted to measure the surfactant sorption characteristics, while unsaturated transport experiments were performed in columns packed with 40-270 mesh Ottawa sand at five initial water contents. Following the introduction of surfactant solution, the rate of water percolation through the sand increased; however, this period of rapid water drainage was followed by decreased water percolation due to the reduction in soil water content and the corresponding decrease in unsaturated hydraulic conductivity behind the surfactant front. The observed changes in water percolation occurred sequentially, and resulted in faster nonreactive solute transport than was observed in the absence of surfactant. A one-dimensional mathematical model accurately described coupled water flow, surfactant, and solute transport under most experimental conditions. Differences between model predictions and experimental data were observed in the column study performed at the lowest water content (0.115 cm3/cm3), which was attributed to surfactant adsorption at the air-water interface. These findings demonstrate the potential influence of surfactants additives on unsaturated water flow and solute transport in soils, and demonstrate a methodology to couple these processes in a predictive modeling tool.

  6. "Switchable water": aqueous solutions of switchable ionic strength.

    PubMed

    Mercer, Sean M; Jessop, Philip G

    2010-04-26

    "Salting out" is a standard method for separating water-soluble organic compounds from water. In this method, adding a large amount of salt to the aqueous solution forces the organic compound out of the aqueous phase. However, the method can not be considered sustainable because it creates highly salty water. A greener alternative would be a method that allows reversible salting out. Herein, we describe aqueous solutions of switchable ionic strength. Aqueous solutions of a diamine in water have essentially zero ionic strength but are converted by CO(2) into solutions of high ionic strength. The change is reversible. Application to the reversible salting out of THF from water is described. PMID:20186910

  7. Anomalous water diffusion in salt solutions

    PubMed Central

    Ding, Yun; Hassanali, Ali A.; Parrinello, Michele

    2014-01-01

    The dynamics of water exhibits anomalous behavior in the presence of different electrolytes. Recent experiments [Kim JS, Wu Z, Morrow AR, Yethiraj A, Yethiraj A (2012) J Phys Chem B 116(39):12007–12013] have found that the self-diffusion of water can either be enhanced or suppressed around CsI and NaCl, respectively, relative to that of neat water. Here we show that unlike classical empirical potentials, ab initio molecular dynamics simulations successfully reproduce the qualitative trends observed experimentally. These types of phenomena have often been rationalized in terms of the “structure-making” or “structure-breaking” effects of different ions on the solvent, although the microscopic origins of these features have remained elusive. Rather than disrupting the network in a significant manner, the electrolytes studied here cause rather subtle changes in both structural and dynamical properties of water. In particular, we show that water in the ab initio molecular dynamics simulations is characterized by dynamic heterogeneity, which turns out to be critical in reproducing the experimental trends. PMID:24522111

  8. Heterogeneous photocatalytic ozonation of 2,4-D in dilute aqueous solution with TiO2 fiber.

    PubMed

    Giri, R R; Ozaki, H; Takanami, R; Taniguchi, S

    2008-01-01

    Photocatalytic ozonation (O(3)/UV/TiO2) is an emerging oxidation method for recalcitrant organic contaminants in water. However, immobilised TiO2 catalysts suffer from reduced photonic efficiency. Therefore, TiO2 catalysts with excellent mechanical and thermal properties and enhanced photonic efficiencies are sought. This paper aimed to elucidate the mineralisation of low concentration 2,4-D (45.0 microM) by O(3)/UV/TiO2 using the world's first high-strength TiO2 fibre in laboratory batch experiments. 2,4-D degradation and TOC removal followed pseudo first-order reaction kinetic. The removal rates for 2,4-D and TOC in O(3)/UV/TiO2 were 1.5 and 2.4-fold larger than the summation of the values for ozonation (O3)) and photocatalysis (UV/TiO2), respectively. O(3)/UV/TiO2 was characterised by few aromatic intermediates with low abundance, fast degradations of aliphatic intermediates and dechlorination as a major step. The significantly enhanced 2,4-D mineralisation in O(3)/UV/TiO2 was attributed to increased ozone dissolution and decomposition, and reduced electron-hole recombination resulting in large number of hydroxyl radical (*OH) formation from more than one parallel path. The discrepancies in the organic carbon mass budget were attributed to few apparently major unidentified intermediates, while chlorine mass balance was reasonably acceptable. The mineralisation efficiency of O(3)/UV/TiO2 with the TiO2 fibre can further be enhanced by optimisation of experimental design parameters. The new TiO2 fibre is very promising to overcome the problem of reduced efficiency of TiO2 catalyst in an immobilised state. PMID:18653956

  9. Equilibrium water and solute uptake in silicone hydrogels.

    PubMed

    Liu, D E; Dursch, T J; Oh, Y; Bregante, D T; Chan, S Y; Radke, C J

    2015-05-01

    Equilibrium water content of and solute partitioning in silicone hydrogels (SiHys) are investigated using gravimetric analysis, fluorescence confocal laser-scanning microscopy (FCLSM), and back extraction with UV/Vis-absorption spectrophotometry. Synthesized silicone hydrogels consist of silicone monomer, hydrophilic monomer, cross-linking agent, and triblock-copolymer macromer used as an amphiphilic compatibilizer to prevent macrophase separation. In all cases, immiscibility of the silicone and hydrophilic polymers results in microphase-separated morphologies. To investigate solute uptake in each of the SiHy microphases, equilibrium partition coefficients are obtained for two hydrophilic solutes (i.e., theophylline and caffeine dissolved in aqueous phosphate-buffered saline) and two oleophilic solutes (i.e., Nile Red and Bodipy Green dissolved in silicone oil), respectively. Measured water contents and aqueous-solute partition coefficients increase linearly with increasing solvent-free hydrophilic-polymer volume fraction. Conversely, oleophilic-solute partition coefficients decrease linearly with rising solvent-free hydrophilic-polymer volume fraction (i.e., decreasing hydrophobic silicone-polymer fraction). We quantitatively predict equilibrium SiHy water and solute uptake assuming that water and aqueous solutes reside only in hydrophilic microdomains, whereas oleophilic solutes partition predominately into silicone microdomains. Predicted water contents and solute partition coefficients are in excellent agreement with experiment. Our new procedure permits a priori estimation of SiHy water contents and solute partition coefficients based solely on properties of silicone and hydrophilic homopolymer hydrogels, eliminating the need for further mixed-polymer-hydrogel experiments. PMID:25725471

  10. Selective production of hemicellulose-derived carbohydrates from wheat straw using dilute HCl or FeCl3 solutions under mild conditions. X-ray and thermo-gravimetric analysis of the solid residues.

    PubMed

    Marcotullio, G; Krisanti, E; Giuntoli, J; de Jong, W

    2011-05-01

    The present work explores the combined production of hemicellulose-derived carbohydrates and an upgraded solid residue from wheat straw using a dilute-acid pretreatment at mild temperature. Dilute aqueous HCl solutions were studied at temperatures of 100 and 120°C, and they were compared to dilute FeCl(3) under the same conditions. Comparable yields of soluble sugars and acetic acid were obtained, affording an almost complete removal of pentoses when using 200 mM aqueous solutions at 120°C. The solid residues of pretreatment were characterized showing a preserved crystallinity of the cellulose, and a almost complete removal of ash forming matter other than Si. Results showed upgraded characteristic of the residues for thermal conversion applications compared to the untreated wheat straw.

  11. Motional Resistance Evaluation of the Quartz Crystal Microbalance to Study the Formation of a Passive Layer in the Interfacial Region of a Copper|Diluted Sulfuric Solution.

    PubMed

    Cuenca, Alejandro; Agrisuelas, Jerónimo; Catalán, Raquel; García-Jareño, José J; Vicente, Francisco

    2015-09-01

    A hyphenated technique based on vis–NIR spectroscopy and electrochemical quartz crystal microbalance with motional resistance monitoring was employed to investigate the dissolution of copper in acid media. Changes in motional resistance, current, mass, and absorbance during copper dissolution allow the evolution of the interfacial region of copper|diluted sulfuric solution to be understood. In particular, motional resistance is presented in this work as a useful tool to observe the evolution of the passive layer at the interface. During the forced copper electrodissolution in sulfuric solution, SO4(2–) favors the formation of soluble [Cu(H2O)6]2+. On the contrary, OH– involves the formation of Cu(H2O)4(OH)2, which precipitates on the electrode surface. The high viscosity and density of Cu(H2O)4(OH)2 formed on surface causes an increase in motional resistance independently of resonance frequency changes. During the copper corrosion in a more natural acidic environment, the results of electrochemical impedance spectra at open circuit potential indicate that corrosion is controlled by the diffusion of copper to the solution at short experimental times. However, copper diffusion is hindered by the formation of a passive layer on the electrode surface at long experimental times. During the copper corrosion, motional resistance shows an oscillatory response because of an oscillatory formation/dissolution of the passive later. Vis–NIR spectroscopy and electrochemical quartz crystal microbalance with motional resistance monitoring give new perspectives for reaching a deep understanding of metal corrosion processes and, in a future, other interfacial processes such as the catalysis or adsorption of (bio)molecules.

  12. Laboratory Measurements Of Pure And Diluted Methanol In Water Ice In The Nir And Mir Wavelength Ranges.

    NASA Astrophysics Data System (ADS)

    Merlin, Frederic; Quirico, E.; Barucci, M. A.; Gourgeot, F.

    2012-10-01

    Observations performed in the mid infrared (MIR) show evidence of large amount of ices in the Galaxy. Water ice is the most abundant but other chemical compounds, such as carbon monoxide and methanol, can be present and be enriched in molecular clouds or protostellar disks (Garrod & Pauly 2011). Methanol forms mainly on ice-covered dust grain surfaces primarily through hydrogenation of CO or from an electron-irradiated H2O-CH4 icy mixture (see Moore & Hudson 1998 or Dartois et al. 1999). These compounds appear to be pristine in the minor bodies of the solar system (Merlin et al. 2012) and were found in comets (Bockelée-Morvan et al. 2004) and on the surface of Trans-Neptunian Objects and Centaurs (Barucci et al. 2012 for instance for methanol). Laboratory measurements are needed to constrain information on the physical and chemical properties of these objects and give constraint on the formation and evolution of the solar system. In the aim to give constraints on the physical properties of H2O and CH3OH from their spectral behavior, we performed laboratory measurements in the observable wavelength ranges accessible from the space and ground based observatories (in the MIR and in the near IR, respectively). We present new laboratory measurements depending on the ratio of each component and the ambient temperature (from 18 to 145K) for the amorphous and the crystalline phases. We focus our analyses on the effects of the dilution level of CH3OH in H2O and the phase changes, especially on the absorption bands located at 2,3 and 3,45 microns (associated to CH asymmetric stretch) and the possible formation of the mono hydrate CH3OH:H2O based on the 3,12 micron band (associated to the OH stretch).

  13. Regional water-quality analysis of 2,4-D and dicamba in river water using gas chromatography-isotope dilution mass spectrometry

    USGS Publications Warehouse

    Thurman, E.M.; Zimmerman, L.R.; Aga, D.S.; Gilliom, R.J.

    2001-01-01

    Gas chromatography with isotope dilution mass spectrometry (GC-MS) and enzyme-linked immunosorbent assay (ELISA) were used in regional National Water Quality Assessment studies of the herbicides, 2,4-D and dicamba, in river water across the United States. The GC-MS method involved solid-phase extraction, derivatized with deutemted 2,4-D, and analysis by selected ion monitoring. The ELISA method was applied after preconcentration with solid-phase extraction. The ELISA method was unreliable because of interference from humic substances that were also isolated by solid-phase extraction. Therefore, GC-MS was used to analyzed 80 samples from river water from 14 basins. The frequency of detection of dicamba (28%) was higher than that for 2,4-D (16%). Concentrations were higher for dicamba than for 2,4-D, ranging from less than the detection limit (<0.05 ??g/L) to 3.77 ??g/L, in spite of 5 times more annual use of 2,4-D as compared to dicamba. These results suggest that 2,4-D degrades more rapidly in the environment than dicamba.

  14. Institutional solutions to drinking water problems: Maine case studies

    SciTech Connect

    Not Available

    1993-03-01

    The paper recounts how four Maine communities sought and found institutional solutions to drinking water problems. Each scenario describes the system, outlines the problems, reviews the chronology of events, points out the lessons learned and gives the system's current status.

  15. Existence of global weak solutions to compressible isentropic finitely extensible nonlinear bead-spring chain models for dilute polymers: The two-dimensional case

    NASA Astrophysics Data System (ADS)

    Barrett, John W.; Süli, Endre

    2016-07-01

    We prove the existence of global-in-time weak solutions to a general class of models that arise from the kinetic theory of dilute solutions of nonhomogeneous polymeric liquids, where the polymer molecules are idealized as bead-spring chains with finitely extensible nonlinear elastic (FENE) type spring potentials. The class of models under consideration involves the unsteady, compressible, isentropic, isothermal Navier-Stokes system in a bounded domain Ω in Rd, d = 2, for the density ρ, the velocity u ˜ and the pressure p of the fluid, with an equation of state of the form p (ρ) =cpργ, where cp is a positive constant and γ > 1. The right-hand side of the Navier-Stokes momentum equation includes an elastic extra-stress tensor, which is the classical Kramers expression. The elastic extra-stress tensor stems from the random movement of the polymer chains and is defined through the associated probability density function that satisfies a Fokker-Planck-type parabolic equation, a crucial feature of which is the presence of a centre-of-mass diffusion term. This extends the result in our paper J.W. Barrett and E. Süli (2016) [9], which established the existence of global-in-time weak solutions to the system for d ∈ { 2 , 3 } and γ >3/2, but the elastic extra-stress tensor required there the addition of a quadratic interaction term to the classical Kramers expression to complete the compactness argument on which the proof was based. We show here that in the case of d = 2 and γ > 1 the existence of global-in-time weak solutions can be proved in the absence of the quadratic interaction term. Our results require no structural assumptions on the drag term in the Fokker-Planck equation; in particular, the drag term need not be corotational. With a nonnegative initial density ρ0 ∈L∞ (Ω) for the continuity equation; a square-integrable initial velocity datum u˜0 for the Navier-Stokes momentum equation; and a nonnegative initial probability density function ψ0

  16. Hydrogen-bonding and vibrational coupling of water in a hydrophobic hydration shell as observed by Raman-MCR and isotopic dilution spectroscopy.

    PubMed

    Ahmed, Mohammed; Singh, Ajay K; Mondal, Jahur A

    2016-01-28

    Hydrogen-bonding and intra/intermolecular vibrational coupling of water next to a hydrophobic molecule (tert-butyl alcohol, TBA) have been studied by Raman multivariate curve resolution (Raman-MCR) and isotopic dilution spectroscopy. Raman-MCR provides the vibrational spectrum of water pertinent to the hydration shell of TBA, which shows a distinct Raman band at around 3660 cm(-1) corresponding to the dangling OH in the hydration shell. The presence of positive charge on the hydrophobe decreases the propensity of dangling OH in the hydration shell, presumably due to unfavorable electrostatic interaction. Analysis of the dangling OH band with isotopic dilution reveals that the 'dangling OH' is intramolecularly coupled with the 'H-bonded OH' of the same water molecule. The hydration water spectrum in the H-bonded OH stretch region (3000-3600 cm(-1)) shows a depletion of weakly H-bonded water (∼3580 cm(-1)) and an increase of strongly H-bonded water (∼3250 cm(-1)), making the average H-bonding stronger in a hydrophobic hydration shell than that in bulk. This strongly H-bonded hydration water exhibits weaker intra- and intermolecular vibrational coupling than that of bulk water. PMID:26725484

  17. Behavior of pure gallium in water and various saline solutions.

    PubMed

    Horasawa, N; Nakajima, H; Takahashi, S; Okabe, T

    1997-12-01

    This study investigated the chemical stability of pure gallium in water and saline solutions in order to obtain fundamental knowledge about the corrosion mechanism of gallium-based alloys. A pure gallium plate (99.999%) was suspended in 50 mL of deionized water, 0.01%, 0.1% or 1% NaCl solution at 24 +/- 2 degrees C for 1, 7, or 28 days. The amounts of gallium released into the solutions were determined by atomic absorption spectrophotometry. The surfaces of the specimens were examined after immersion by x-ray diffractometry (XRD) and x-ray photoelectron spectroscopy (XPS). In the solutions containing 0.1% or more NaCl, the release of gallium ions into the solution was lowered when compared to deionized water after 28-day immersion. Gallium oxide monohydroxide was found by XRD on the specimens immersed in deionized water after 28-day immersion. XPS indicated the formation of gallium oxide/hydroxide on the specimens immersed in water or 0.01% NaCl solution. The chemical stability of pure solid gallium was strongly affected by the presence of Cl- ions in the aqueous solution.

  18. A pH-responsive and magnetically separable dynamic system for efficient removal of highly dilute antibiotics in water.

    PubMed

    Liu, Wanpeng; Ma, Jianqing; Shen, Chensi; Wen, Yuezhong; Liu, Weiping

    2016-03-01

    In order to control the antibiotic-related crisis and reduce the negative impacts on the environment and human health, it is urgent to develop effective technologies to eliminate residual antibiotics in water. Herein, we successfully fabricated a novel, pH-responsive and magnetically separable dynamic system for micropollutant adsorption and oxidation degradation in graphene oxide (GO)/nanoscale zero-valent iron (nZVI) composite with macroscopic structure. The pH-responsive self-assembly behavior of GO/nZVI composite was explored. The macroscopic structure of GO/nZVI composite serves as an excellent adsorbent for antibiotic removal in water. The adsorption process is fast and highly efficient even in high salty and humic acid containing water under acid to neutral conditions. After removal antibiotics, GO/nZVI composite is conveniently separated by magnetic system and put into alkaline solution (pH > 9) for adsorbent regeneration. Interestingly, it is found that at pH > 9, GO/nZVI composite disassembles partly upon increasing pH values, leading to the elution of antibiotics for efficient antibiotics degradation by ozonization. More importantly, this pH-responsive GO/nZVI system exhibits high removal efficiency, high stability, reusability and easily separation, making it a promising method for treatment of water with micropollutants. PMID:26724436

  19. A pH-responsive and magnetically separable dynamic system for efficient removal of highly dilute antibiotics in water.

    PubMed

    Liu, Wanpeng; Ma, Jianqing; Shen, Chensi; Wen, Yuezhong; Liu, Weiping

    2016-03-01

    In order to control the antibiotic-related crisis and reduce the negative impacts on the environment and human health, it is urgent to develop effective technologies to eliminate residual antibiotics in water. Herein, we successfully fabricated a novel, pH-responsive and magnetically separable dynamic system for micropollutant adsorption and oxidation degradation in graphene oxide (GO)/nanoscale zero-valent iron (nZVI) composite with macroscopic structure. The pH-responsive self-assembly behavior of GO/nZVI composite was explored. The macroscopic structure of GO/nZVI composite serves as an excellent adsorbent for antibiotic removal in water. The adsorption process is fast and highly efficient even in high salty and humic acid containing water under acid to neutral conditions. After removal antibiotics, GO/nZVI composite is conveniently separated by magnetic system and put into alkaline solution (pH > 9) for adsorbent regeneration. Interestingly, it is found that at pH > 9, GO/nZVI composite disassembles partly upon increasing pH values, leading to the elution of antibiotics for efficient antibiotics degradation by ozonization. More importantly, this pH-responsive GO/nZVI system exhibits high removal efficiency, high stability, reusability and easily separation, making it a promising method for treatment of water with micropollutants.

  20. Reorientation and Allied Dynamics in Water and Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Laage, Damien; Stirnemann, Guillaume; Sterpone, Fabio; Rey, Rossend; Hynes, James T.

    2011-05-01

    The reorientation of a water molecule is important for a host of phenomena, ranging over—in an only partial listing—the key dynamic hydrogen-bond network restructuring of water itself, aqueous solution chemical reaction mechanisms and rates, ion transport in aqueous solution and membranes, protein folding, and enzymatic activity. This review focuses on water reorientation and related dynamics in pure water, and for aqueous solutes with hydrophobic, hydrophilic, and amphiphilic character, ranging from tetra-methylurea to halide ions and amino acids. Attention is given to the application of theory, simulation, and experiment in the probing of these dynamics, in usefully describing them, and in assessing the description. Special emphasis is placed on a novel sudden, large-amplitude jump mechanism for water reorientation, which contrasts with the commonly assumed Debye rotational diffusion mechanism, characterized by small-amplitude angular motion. Some open questions and directions for further research are also discussed.

  1. Simultaneous photometric determination of albumin and total protein in animal blood plasma employing a multicommutated flow system to carried out on line dilution and reagents solutions handling

    NASA Astrophysics Data System (ADS)

    Luca, Gilmara C.; Reis, Boaventura F.

    2004-02-01

    An automatic flow procedure for the simultaneous determination of albumin and total protein in blood plasma samples is proposed. The flow network comprised a set of three-way solenoid valves assembled to implement the multicommutation. The flow set up was controlled by means of a computer equipped with an electronic interface card which running a software wrote in QUICKBASIC 4.5 performed on line programmed dilution to allow the determination of both albumin and total protein in blood plasma. The photometric methods based on Bromocresol Green and Biuret reagents were selected for determination of albumin and total protein, respectively. Two LEDs based photometers coupled together the flow cells were employed as detector. After the adjustment of the operational parameters the proposed system presented the following features: an analytical throughput of 45 sample processing per hour for two analytes; relative standard deviations of 1.5 and 0.8% ( n=10) for a typical sample presenting 34 g l -1 albumin and 90 g l -1 total protein, respectively; linear responses ranging from 0 to 15 g l -1 albumin ( r=0.998) and total protein ( r=0.999); sample and reagents consumption, 140 μl serum solution, 0.015 mg VBC and 0.432 mg CuSO 4 per determination, respectively. Applying the paired t-test between results obtained using the proposed system and reference methods no significant difference at 95 and 90% confidence level for albumin and total protein, respectively, were observed.

  2. Simultaneous photometric determination of albumin and total protein in animal blood plasma employing a multicommutated flow system to carried out on line dilution and reagents solutions handling.

    PubMed

    Luca, Gilmara C; Reis, Boaventura F

    2004-02-01

    An automatic flow procedure for the simultaneous determination of albumin and total protein in blood plasma samples is proposed. The flow network comprised a set of three-way solenoid valves assembled to implement the multicommutation. The flow set up was controlled by means of a computer equipped with an electronic interface card which running a software wrote in QUICKBASIC 4.5 performed on line programmed dilution to allow the determination of both albumin and total protein in blood plasma. The photometric methods based on Bromocresol Green and Biuret reagents were selected for determination of albumin and total protein, respectively. Two LEDs based photometers coupled together the flow cells were employed as detector. After the adjustment of the operational parameters the proposed system presented the following features: an analytical throughput of 45 sample processing per hour for two analytes; relative standard deviations of 1.5 and 0.8% (n=10) for a typical sample presenting 34 g l(-1) albumin and 90 g l(-1) total protein, respectively; linear responses ranging from 0 to 15 g l(-1) albumin (r=0.998) and total protein (r=0.999); sample and reagents consumption, 140 microl serum solution, 0.015 mg VBC and 0.432 mg CuSO4 per determination, respectively. Applying the paired t-test between results obtained using the proposed system and reference methods no significant difference at 95 and 90% confidence level for albumin and total protein, respectively, were observed.

  3. Investigation of the spreading and dilution of domestic waste water inputs into a tidal bay using the finite-volume model FVCOM

    NASA Astrophysics Data System (ADS)

    Lettmann, Karsten; Wolff, Jörg-Olaf; Liebezeit, Gerd; Meier, Georg

    2010-05-01

    The 'Jade Bay' is a tidal bay located in the western part of the German Wadden Sea, southern North-Sea coast. During particularly heavy rain falls, rain water mixed with domestic waste water is discharged into the bay due to the limited capacities of the waste water treatment plant of the city of Wilhelmshaven. As the discharge point is located only a few hundred meters from a public bathing beach it is important to know spreading and dilution of the waste waters by tidal and wind-driven mixing. To model the behaviour of the waste water plumes, the unstructured mesh finite-volume model FVCOM (Chen and al., 2003) is used, which allows to cover the large area of the Jade and the nearby North Sea with a relatively high resolution near the point of discharge and a coarser resolution at the outer edges of the study side. We adapted the included sediment module of FVCOM to handle the sedimentation, decay and evolution in the bottom sediments of the discharged waste water particles, especially with respect to bacteria. Furthermore, alternative discharge points located in the interior of the Jade bay were tested, which might be more suited for a faster dilution and a smaller residence time of the waste water particles in the tidal bay.

  4. Hammerhead ribozyme activity and oligonucleotide duplex stability in mixed solutions of water and organic compounds

    PubMed Central

    Nakano, Shu-ichi; Kitagawa, Yuichi; Miyoshi, Daisuke; Sugimoto, Naoki

    2014-01-01

    Nucleic acids are useful for biomedical targeting and sensing applications in which the molecular environment is different from that of a dilute aqueous solution. In this study, the influence of various types of mixed solutions of water and water-soluble organic compounds on RNA was investigated by measuring the catalytic activity of the hammerhead ribozyme and the thermodynamic stability of an oligonucleotide duplex. The compounds with a net neutral charge, such as poly(ethylene glycol), small primary alcohols, amide compounds, and aprotic solvent molecules, added at high concentrations changed the ribozyme-catalyzed RNA cleavage rate, with the magnitude of the effect dependent on the NaCl concentration. These compounds also changed the thermodynamic stability of RNA base pairs of an oligonucleotide duplex and its dependence on the NaCl concentration. Specific interactions with RNA molecules and reduced water activity could account for the inhibiting effects on the ribozyme catalysis and destabilizing effects on the duplex stability. The salt concentration dependence data correlated with the dielectric constant, but not with water activity, viscosity, and the size of organic compounds. This observation suggests the significance of the dielectric constant effects on the RNA reactions under molecular crowding conditions created by organic compounds. PMID:25161873

  5. Water--Problems and Solutions. A Report Concerning the Problems and Solutions of Negative Water Balance.

    ERIC Educational Resources Information Center

    Ewert, Alan

    Outdoor leaders constantly face problems created by water shortage and, to act effectively, must thoroughly understand the body's use of water and the ways to delay dehydration when water shortage occurs. Dehydration begins when there is a negative water balance, or more water lost than ingested, and progresses from the stage of dryness, to the…

  6. Solubility of organic solutes in ethanol-water mixtures

    SciTech Connect

    Li, A.; Yalkowsky, S.H.

    1994-12-31

    The log-linear solubilization model was applied to experimental solubility data of 109 organic compounds in ethanol/water mixtures. It is found that the extent of solubilization strongly depends on the solute hydrophobicity and the ethanol concentration in the solvent mixture. Patterns of deviation from the log-linear model are related to the structure and hydrophobicity of the solutes. Predictive equations were obtained by regression of the experimental data with solute octanol-water partition coefficient (log K{sub ow}). The logarithms of the solubilization and the solute log K{sub ow} range over eleven orders of magnitude. The solubilities of chrysene, perylene, benzo(a)pyrene, pentachlorobenzene, and hexachlorobenzene in ethanol/water mixtures were experimentally determined, and the results fit well into the model.

  7. Reactive uptake of NO3 on pure water and ionic solutions

    NASA Astrophysics Data System (ADS)

    Rudich, Yinon; Talukdar, Ranajit K.; Ravishankara, A. R.; Fox, R. W.

    1996-09-01

    The reactive uptake coefficients (γ) of NO3 onto pure water and dilute solutions of NaCl, NaBr, and NaNO2 were measured using a wetted-wall flow-tube setup combined with a long-path absorption cell for the detection of NO3. The measured γ values were in the range 1.5 × 10-4 - 6 × 10-3, depending on the salt concentration in the water. By measuring γ as a function of salt concentration, HD�򉾊.5 for NO3 in water was determined to be (1.9 ± 0.4) × 10-3 M atm-1 cm s-0.5 at 273 K, assuming that the rate coefficient for the reaction of NO3 with Cl- is 2.76 × 106 M-1 s-1 at 273 K. The Henry's law coefficient for NO3 in water is estimated to be 0.6 ± 0.3 M atm-1, assuming that the diffusion coefficient of NO3 in water is D�� = (1.0 ± 0.5) × 10-5 cm2 s-1. Uptake of NO3 on pure water is interpreted as due to reaction of NO3(aq) with H2O(��) to produce HNO3 and OH in the liquid phase. Implications of these findings to the chemistry of NO3 in the troposphere are also discussed.

  8. Dynamics of Hydration Water in Sugars and Peptides Solutions

    SciTech Connect

    Perticaroli, Stefania; Nakanishi, Masahiro; Pashkovski, Eugene; Sokolov, Alexei P

    2013-01-01

    We analyzed solute and solvent dynamics of sugars and peptides aqueous solutions using extended epolarized light scattering (EDLS) and broadband dielectric spectroscopies (BDS). Spectra measured with both techniques reveal the same mechanism of rotational diffusion of peptides molecules. In the case of sugars, this solute reorientational relaxation can be isolated by EDLS measurements, whereas its ontribution to the dielectric spectra is almost negligible. In the presented analysis, we characterize the hydration water in terms of hydration number and retardation ratio between relaxation times of hydration and bulk water. Both techniques provide similar estimates of . The retardation imposed on the hydration water by sugars is 3.3 1.3 and involves only water molecules hydrogen-bonded (HB) to solutes ( 3 water molecules per sugar OH-group). In contrast, polar peptides cause longer range erturbations beyond the first hydration shell, and between 2.8 and 8, increasing with the number of chemical groups engaged in HB formation. We demonstrate that chemical heterogeneity and specific HB interactions play a crucial role in hydration dynamics around polar solutes. The obtained results help to disentangle the role of excluded volume and enthalpic contributions in dynamics of hydration water at the interface with biological molecules.

  9. Thermodynamic description of Tc(iv) solubility and hydrolysis in dilute to concentrated NaCl, MgCl2 and CaCl2 solutions.

    PubMed

    Yalçıntaş, Ezgi; Gaona, Xavier; Altmaier, Marcus; Dardenne, Kathy; Polly, Robert; Geckeis, Horst

    2016-06-01

    We present the first systematic investigation of Tc(iv) solubility, hydrolysis and speciation in dilute to concentrated NaCl, MgCl2 and CaCl2 systems, and comprehensive thermodynamic and activity models for the system Tc(4+)-H(+)-Na(+)-Mg(2+)-Ca(2+)-OH(-)-Cl(-)-H2O using both SIT and Pitzer approaches. The results are advancing the fundamental scientific understanding of Tc(iv) solution chemistry and are highly relevant in the applied context of nuclear waste disposal. The solubility of Tc(iv) was investigated in carbonate-free NaCl-NaOH (0.1-5.0 M), MgCl2 (0.25-4.5 M) and CaCl2 (0.25-4.5 M) solutions within 2 ≤ pHm≤ 14.5. Undersaturation solubility experiments were performed under an Ar atmosphere at T = 22 ± 2 °C. Strongly reducing conditions (pe + pHm≤ 2) were imposed with Na2S2O4, SnCl2 and Fe powder to stabilize technetium in the +IV redox state. The predominance of Tc(iv) in the aqueous phase was confirmed by solvent extraction and XANES/EXAFS spectroscopy. Solid phase characterization was accomplished after attaining thermodynamic equilibrium using XRD, SEM-EDS, XANES/EXAFS, TG-DTA and quantitative chemical analysis, and indicated that TcO2·0.6H2O(s) exerts solubility-control in all evaluated systems. The definition of the polyatomic Tc3O5(2+) species instead of TcO(2+) is favoured under acidic conditions, consistently with slope analysis (mTcvs. pHm) of the solubility data gained in this work and spectroscopic evidence previously reported in the literature. The additional formation of Tc(iv)-OH/O-Cl aqueous species in concentrated chloride media ([Cl(-)] = 9 M) and pHm≤ 4 is suggested by solubility and EXAFS data. The pH-independent behaviour of the solubility observed under weakly acidic to weakly alkaline pHm conditions can be explained with the equilibrium reaction TcO2·0.6H2O(s) + 0.4H2O(l) ⇔ TcO(OH)2(aq). Solubility data determined in dilute NaCl systems with pHm≥ 11 follow a well-defined slope of +1, consistent with the predominance of

  10. Thermodynamic description of Tc(iv) solubility and hydrolysis in dilute to concentrated NaCl, MgCl2 and CaCl2 solutions.

    PubMed

    Yalçıntaş, Ezgi; Gaona, Xavier; Altmaier, Marcus; Dardenne, Kathy; Polly, Robert; Geckeis, Horst

    2016-06-01

    We present the first systematic investigation of Tc(iv) solubility, hydrolysis and speciation in dilute to concentrated NaCl, MgCl2 and CaCl2 systems, and comprehensive thermodynamic and activity models for the system Tc(4+)-H(+)-Na(+)-Mg(2+)-Ca(2+)-OH(-)-Cl(-)-H2O using both SIT and Pitzer approaches. The results are advancing the fundamental scientific understanding of Tc(iv) solution chemistry and are highly relevant in the applied context of nuclear waste disposal. The solubility of Tc(iv) was investigated in carbonate-free NaCl-NaOH (0.1-5.0 M), MgCl2 (0.25-4.5 M) and CaCl2 (0.25-4.5 M) solutions within 2 ≤ pHm≤ 14.5. Undersaturation solubility experiments were performed under an Ar atmosphere at T = 22 ± 2 °C. Strongly reducing conditions (pe + pHm≤ 2) were imposed with Na2S2O4, SnCl2 and Fe powder to stabilize technetium in the +IV redox state. The predominance of Tc(iv) in the aqueous phase was confirmed by solvent extraction and XANES/EXAFS spectroscopy. Solid phase characterization was accomplished after attaining thermodynamic equilibrium using XRD, SEM-EDS, XANES/EXAFS, TG-DTA and quantitative chemical analysis, and indicated that TcO2·0.6H2O(s) exerts solubility-control in all evaluated systems. The definition of the polyatomic Tc3O5(2+) species instead of TcO(2+) is favoured under acidic conditions, consistently with slope analysis (mTcvs. pHm) of the solubility data gained in this work and spectroscopic evidence previously reported in the literature. The additional formation of Tc(iv)-OH/O-Cl aqueous species in concentrated chloride media ([Cl(-)] = 9 M) and pHm≤ 4 is suggested by solubility and EXAFS data. The pH-independent behaviour of the solubility observed under weakly acidic to weakly alkaline pHm conditions can be explained with the equilibrium reaction TcO2·0.6H2O(s) + 0.4H2O(l) ⇔ TcO(OH)2(aq). Solubility data determined in dilute NaCl systems with pHm≥ 11 follow a well-defined slope of +1, consistent with the predominance of

  11. Theory for the solvation of nonpolar solutes in water.

    PubMed

    Urbic, T; Vlachy, V; Kalyuzhnyi, Yu V; Dill, K A

    2007-11-01

    We recently developed an angle-dependent Wertheim integral equation theory (IET) of the Mercedes-Benz (MB) model of pure water [Silverstein et al., J. Am. Chem. Soc. 120, 3166 (1998)]. Our approach treats explicitly the coupled orientational constraints within water molecules. The analytical theory offers the advantage of being less computationally expensive than Monte Carlo simulations by two orders of magnitude. Here we apply the angle-dependent IET to studying the hydrophobic effect, the transfer of a nonpolar solute into MB water. We find that the theory reproduces the Monte Carlo results qualitatively for cold water and quantitatively for hot water.

  12. Theory for the solvation of nonpolar solutes in water

    NASA Astrophysics Data System (ADS)

    Urbic, T.; Vlachy, V.; Kalyuzhnyi, Yu. V.; Dill, K. A.

    2007-11-01

    We recently developed an angle-dependent Wertheim integral equation theory (IET) of the Mercedes-Benz (MB) model of pure water [Silverstein et al., J. Am. Chem. Soc. 120, 3166 (1998)]. Our approach treats explicitly the coupled orientational constraints within water molecules. The analytical theory offers the advantage of being less computationally expensive than Monte Carlo simulations by two orders of magnitude. Here we apply the angle-dependent IET to studying the hydrophobic effect, the transfer of a nonpolar solute into MB water. We find that the theory reproduces the Monte Carlo results qualitatively for cold water and quantitatively for hot water.

  13. Theory for the solvation of nonpolar solutes in water.

    PubMed

    Urbic, T; Vlachy, V; Kalyuzhnyi, Yu V; Dill, K A

    2007-11-01

    We recently developed an angle-dependent Wertheim integral equation theory (IET) of the Mercedes-Benz (MB) model of pure water [Silverstein et al., J. Am. Chem. Soc. 120, 3166 (1998)]. Our approach treats explicitly the coupled orientational constraints within water molecules. The analytical theory offers the advantage of being less computationally expensive than Monte Carlo simulations by two orders of magnitude. Here we apply the angle-dependent IET to studying the hydrophobic effect, the transfer of a nonpolar solute into MB water. We find that the theory reproduces the Monte Carlo results qualitatively for cold water and quantitatively for hot water. PMID:17994825

  14. Dilution refrigeration for space applications

    NASA Technical Reports Server (NTRS)

    Israelsson, U. E.; Petrac, D.

    1990-01-01

    Dilution refrigerators are presently used routinely in ground based applications where temperatures below 0.3 K are required. The operation of a conventional dilution refrigerator depends critically on the presence of gravity. To operate a dilution refrigerator in space many technical difficulties must be overcome. Some of the anticipated difficulties are identified in this paper and possible solutions are described. A single cycle refrigerator is described conceptually that uses forces other than gravity to function and the stringent constraints imposed on the design by requiring the refrigerator to function on the earth without using gravity are elaborated upon.

  15. Shallow water equations: viscous solutions and inviscid limit

    NASA Astrophysics Data System (ADS)

    Chen, Gui-Qiang; Perepelitsa, Mikhail

    2012-12-01

    We establish the inviscid limit of the viscous shallow water equations to the Saint-Venant system. For the viscous equations, the viscosity terms are more degenerate when the shallow water is close to the bottom, in comparison with the classical Navier-Stokes equations for barotropic gases; thus, the analysis in our earlier work for the classical Navier-Stokes equations does not apply directly, which require new estimates to deal with the additional degeneracy. We first introduce a notion of entropy solutions to the viscous shallow water equations and develop an approach to establish the global existence of such solutions and their uniform energy-type estimates with respect to the viscosity coefficient. These uniform estimates yield the existence of measure-valued solutions to the Saint-Venant system generated by the viscous solutions. Based on the uniform energy-type estimates and the features of the Saint-Venant system, we further establish that the entropy dissipation measures of the viscous solutions for weak entropy-entropy flux pairs, generated by compactly supported C 2 test-functions, are confined in a compact set in H -1, which yields that the measure-valued solutions are confined by the Tartar-Murat commutator relation. Then, the reduction theorem established in Chen and Perepelitsa [5] for the measure-valued solutions with unbounded support leads to the convergence of the viscous solutions to a finite-energy entropy solution of the Saint-Venant system with finite-energy initial data, which is relative with respect to the different end-states of the bottom topography of the shallow water at infinity. The analysis also applies to the inviscid limit problem for the Saint-Venant system in the presence of friction.

  16. Solution properties of targacanthin (water-soluble part of gum tragacanth exudate from Astragalus gossypinus).

    PubMed

    Mohammadifar, Mohammad Amin; Musavi, Seyed Mohammad; Kiumarsi, Amir; Williams, Peter A

    2006-02-28

    Solution properties of tragacanthin (the water-soluble part of gum tragacanth) were studied by gel permeation chromatography (GPC) combined with multi-angle light scattering and viscometry at 25 degrees C. Photon correlation spectroscopy was used to determine the hydrodynamic radius. Ultrasonic degradation was applied to obtain biopolymer fractions of different molecular weights. The dependence of intrinsic viscosity [eta] and radius of gyration (s2)z(1/2) on weight average molecular mass M(w) for this biopolymer were found to be [eta] = 9.077 x 10(-5) M(w)(0.87) (dL g(-1)) and (s2)z(1/2) in the range of M(w) from 1.8 x 10(5) to 1.6 x 10(6). The conformational parameters of tragacanthin were calculated to be 1111 nm for molar mass per unit contour length (M(L)), 26 nm for persistence length (q) and 1.87 ratio of R(g)/R(h). It was found that the Smidsrød parameter B, the empirical stiffness parameter was 0.013, which is lower than that of several polysaccharides indicating the stiff backbone for tragacanthin. The rheological behavior of aqueous solutions of gum tragacanth and its insoluble and soluble fractions (bassorin and tragacanthin, respectively) were studied. For concentrations equal to 1%, at 25 degrees C and in the absence of salt, bassorin solution showed the highest viscosity and shear thinning behaviour. Power law and Williamson models were used to describe the rheological behaviour of bassorin and tragacanthin, respectively. Oscillatory shear experiments showed a gel like structure for the bassorin but for tragacanthin the oscillatory data were as would be expected for semi-dilute to concentrated solution of entangled, random coil polymers. NaCl changed the steady and oscillatory rheological properties of both fractions and in this way the final viscosity of bassorin was even less than tragacanthin. The calculated activation energy for bassorin and tragacanthin indicated a more rapid decrease in viscosity with temperature for tragacanthin. The plot of

  17. Effect of phosphorus fluctuation caused by river water dilution in eutrophic lake on competition between blue-green alga Microcystis aeruginosa and diatom Cyclotella sp.

    PubMed

    Amano, Yoshimasa; Sakai, Yusuke; Sekiya, Takumi; Takeya, Kimitaka; Taki, Kazuo; Machida, Motoi

    2010-01-01

    Tega-numa (Lake Tega) is one of the eutrophic lakes in Japan. For the improvement of water quality in Lake Tega, the North-chiba Water Conveyance Channel was constructed in 2000, which transfer water from Tone River into the lake. After 2000, the dominant species of diatoms, mainly Cyclotella sp., have been replacing blue-green algae, mainly Microcystis aeruginosa in Lake Tega. This transition of dominant species would be due to the dilution, but the detail mechanism has not been understood yet. This study examined the relationship between phosphorus fluctuation caused by river water dilution to Lake Tega and dominance of algal species, M. aeruginosa or Cyclotella sp. based on the single-species and the mixed-species culture experiments. The single-species culture experiment showed that the half-saturation constant and uptake rate of phosphorus were one order lower and seven times higher for M. aeruginosa than those for Cyclotella sp. These findings implied that M. aeruginosa would possess a potential for the growth and survival over Cyclotella sp. in the phosphorus limited condition. The superiority of M. aeruginosa was reflected in the outcome of the mixed-species culture experiment, i.e., dominance of M. aeruginosa, even phosphorus concentration was lowered to 0.01 mg-P/L. Therefore, it could be concluded that the decrease in phosphorus concentration due to the river water dilution to Lake Tega would be interpreted as a minor factor for the transition of dominant species from M. aeruginosa to Cyclotella sp. PMID:21235152

  18. Adsorption of HMF from water/DMSO solutions onto hydrophobic zeolites: experiment and simulation.

    PubMed

    Xiong, Ruichang; León, Marta; Nikolakis, Vladimiros; Sandler, Stanley I; Vlachos, Dionisios G

    2014-01-01

    The adsorption of 5-hydroxymethylfurfural (HMF), DMSO, and water from binary and ternary mixtures in hydrophobic silicalite-1 and dealuminated Y (DAY) zeolites at ambient conditions was studied by experiments and molecular modeling. HMF and DMSO adsorption isotherms were measured and compared to those calculated using a combination of grand canonical Monte Carlo and expanded ensemble (GCMC-EE) simulations. A method based on GCMC-EE simulations for dilute solutions combined with the Redlich-Kister (RK) expansion (GCMC-EE-RK) is introduced to calculate the isotherms over a wide range of concentrations. The simulations, using literature force fields, are in reasonable agreement with experimental data. In HMF/water binary mixtures, large-pore hydrophobic zeolites are much more effective for HMF adsorption but less selective because large pores allow water adsorption because of H2 O-HMF attraction. In ternary HMF/DMSO/water mixtures, HMF loading decreases with increasing DMSO fraction, rendering the separation of HMF from water/DMSO mixtures by adsorption difficult. The ratio of the energetic interaction in the zeolite to the solvation free energy is a key factor in controlling separation from liquid mixtures. Overall, our findings could have an impact on the separation and catalytic conversion of HMF and the rational design of nanoporous adsorbents for liquid-phase separations in biomass processing. PMID:24106213

  19. Adsorption of HMF from water/DMSO solutions onto hydrophobic zeolites: experiment and simulation.

    PubMed

    Xiong, Ruichang; León, Marta; Nikolakis, Vladimiros; Sandler, Stanley I; Vlachos, Dionisios G

    2014-01-01

    The adsorption of 5-hydroxymethylfurfural (HMF), DMSO, and water from binary and ternary mixtures in hydrophobic silicalite-1 and dealuminated Y (DAY) zeolites at ambient conditions was studied by experiments and molecular modeling. HMF and DMSO adsorption isotherms were measured and compared to those calculated using a combination of grand canonical Monte Carlo and expanded ensemble (GCMC-EE) simulations. A method based on GCMC-EE simulations for dilute solutions combined with the Redlich-Kister (RK) expansion (GCMC-EE-RK) is introduced to calculate the isotherms over a wide range of concentrations. The simulations, using literature force fields, are in reasonable agreement with experimental data. In HMF/water binary mixtures, large-pore hydrophobic zeolites are much more effective for HMF adsorption but less selective because large pores allow water adsorption because of H2 O-HMF attraction. In ternary HMF/DMSO/water mixtures, HMF loading decreases with increasing DMSO fraction, rendering the separation of HMF from water/DMSO mixtures by adsorption difficult. The ratio of the energetic interaction in the zeolite to the solvation free energy is a key factor in controlling separation from liquid mixtures. Overall, our findings could have an impact on the separation and catalytic conversion of HMF and the rational design of nanoporous adsorbents for liquid-phase separations in biomass processing.

  20. Assessing potential effects of highway runoff on receiving-water quality at selected sites in Oregon with the Stochastic Empirical Loading and Dilution Model (SELDM)

    USGS Publications Warehouse

    Risley, John C.; Granato, Gregory E.

    2014-01-01

    6. An analysis of the use of grab sampling and nonstochastic upstream modeling methods was done to evaluate the potential effects on modeling outcomes. Additional analyses using surrogate water-quality datasets for the upstream basin and highway catchment were provided for six Oregon study sites to illustrate the risk-based information that SELDM will produce. These analyses show that the potential effects of highway runoff on receiving-water quality downstream of the outfall depends on the ratio of drainage areas (dilution), the quality of the receiving water upstream of the highway, and the concentration of the criteria of the constituent of interest. These analyses also show that the probability of exceeding a water-quality criterion may depend on the input statistics used, thus careful selection of representative values is important.

  1. Bubble formation in water with addition of a hydrophobic solute.

    PubMed

    Okamoto, Ryuichi; Onuki, Akira

    2015-07-01

    We show that phase separation can occur in a one-component liquid outside its coexistence curve (CX) with addition of a small amount of a solute. The solute concentration at the transition decreases with increasing the difference of the solvation chemical potential between liquid and gas. As a typical bubble-forming solute, we consider O2 in ambient liquid water, which exhibits mild hydrophobicity and its critical temperature is lower than that of water. Such a solute can be expelled from the liquid to form gaseous domains while the surrounding liquid pressure is higher than the saturated vapor pressure p cx. This solute-induced bubble formation is a first-order transition in bulk and on a partially dried wall, while a gas film grows continuously on a completely dried wall. We set up a bubble free energy ΔG for bulk and surface bubbles with a small volume fraction ϕ. It becomes a function of the bubble radius R under the Laplace pressure balance. Then, for sufficiently large solute densities above a threshold, ΔG exhibits a local maximum at a critical radius and a minimum at an equilibrium radius. We also examine solute-induced nucleation taking place outside CX, where bubbles larger than the critical radius grow until attainment of equilibrium. PMID:26142694

  2. Water Flow and Solute Transport in Heterogeneous Soils: A new Multicompartment Sampler and a Theoretical Toolkit for Data Analysis

    NASA Astrophysics Data System (ADS)

    de Rooij, G. H.; Hogervorst, F. A.; Bloem, E.; Stagnitti, F.; Cirpka, O. A.

    2007-12-01

    Water flow and solute transport in soils are invariably affected by heterogeneity and often by preferential flow, both typically occurring within 1 square meter. Paradoxically, we need to understand flow and transport at this small scale to quantify them at the field and regional scales. This paradox arises from the geometry of soils: the scale in the direction of the flow is orders of magnitude smaller than the scales perpendicular to it. We present a coherent package of experimental and theoretical tools to observe and analyze small-scale variations (within 0.1- 1 square meter) of water and solute fluxes. Multicompartment samplers can measure small-scale water and solute movement in space and time, particularly in temperate climates. The latest generation of samplers allows repeated extraction of percolate samples in situ under controlled suction to minimize disturbance of the unsaturated flow field. After discussing the general principle of such samplers, a method will be presented to estimate the required total sampling area of a sampler from the degree of flow convergence in a soil. In recent years, we improved our ability to analyze the data produced by multicompartment samplers. The spatial solute distribution curve as the spatial equivalent of the travel time distribution was parameterized and physically interpreted. Both distributions were unified in the leaching surface, which has tremendous potential for detailed interpretation and model evaluation. Multicompartment samplers can also help identify the nature of the solute transport process. Recently, we expanded the theory of solute dilution to make it applicable to multicompartment sampler data. We will demonstrate how dilution theory can be used to determine the predominance of a convective-dispersive or a stochastic-convective transport regime during a tracer experiment.

  3. Spectral reflectance of selected aqueous solutions for water quality applications

    NASA Technical Reports Server (NTRS)

    Querr, M. R.; Waring, R. C.; Holland, W. E.; Nijm, W.; Hale, G. M.

    1972-01-01

    The relative specular reflectances of individual aqueous solutions having a particular chemical salt content were measured in the 2 to 20 micrometers region of the infrared component or radiant flux. Distilled water was the reflectance standard. The angle of incidence was 70.03 deg plus or minus 0.23 deg. Absolute reflectances of the solutions for the same polarization and angle of incidence were computed by use of the measured relative reflectances, one of the Fresnel equations, and the optical constants of distilled water. Phase shift and phase difference spectra were obtained by respectively applying a Kramers-Kronig dispersion analysis to the absolute and relative reflectance spectra. The optical constants of the solutions were determined by algorithms commonly associated with the Kramers-Kronig analysis. Spectral signatures that qualitatively and quantitatively characterize the solute and that show structure of the infrared bands of water were noted in the phase difference spectra. The relative and absolute reflectances, the phase shift and phase difference spectra and the optical constants are presented in graphical form. Application of these results to remote sensing of the chemical quality of natural waters is discussed briefly.

  4. Determination of Glyphosate, its Degradation Product Aminomethylphosphonic Acid, and Glufosinate, in Water by Isotope Dilution and Online Solid-Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry

    USGS Publications Warehouse

    Meyer, Michael T.; Loftin, Keith A.; Lee, Edward A.; Hinshaw, Gary H.; Dietze, Julie E.; Scribner, Elisabeth A.

    2009-01-01

    The U.S. Geological Survey method (0-2141-09) presented is approved for the determination of glyphosate, its degradation product aminomethylphosphonic acid (AMPA), and glufosinate in water. It was was validated to demonstrate the method detection levels (MDL), compare isotope dilution to standard addition, and evaluate method and compound stability. The original method USGS analytical method 0-2136-01 was developed using liquid chromatography/mass spectrometry and quantitation by standard addition. Lower method detection levels and increased specificity were achieved in the modified method, 0-2141-09, by using liquid chromatography/tandem mass spectrometry (LC/MS/MS). The use of isotope dilution for glyphosate and AMPA and pseudo isotope dilution of glufosinate in place of standard addition was evaluated. Stable-isotope labeled AMPA and glyphosate were used as the isotope dilution standards. In addition, the stability of glyphosate and AMPA was studied in raw filtered and derivatized water samples. The stable-isotope labeled glyphosate and AMPA standards were added to each water sample and the samples then derivatized with 9-fluorenylmethylchloroformate. After derivatization, samples were concentrated using automated online solid-phase extraction (SPE) followed by elution in-line with the LC mobile phase; the compounds separated and then were analyzed by LC/MS/MS using electrospray ionization in negative-ion mode with multiple-reaction monitoring. The deprotonated derivatized parent molecule and two daughter-ion transition pairs were identified and optimized for glyphosate, AMPA, glufosinate, and the glyphosate and AMPA stable-isotope labeled internal standards. Quantitative comparison between standard addition and isotope dilution was conducted using 473 samples analyzed between April 2004 and June 2006. The mean percent difference and relative standard deviation between the two quantitation methods was 7.6 plus or minus 6.30 (n = 179), AMPA 9.6 plus or minus 8

  5. Barriers and Solutions to Smart Water Grid Development.

    PubMed

    Cheong, So-Min; Choi, Gye-Woon; Lee, Ho-Sun

    2016-03-01

    This limited review of smart water grid (SWG) development, challenges, and solutions provides an initial assessment of early attempts at operating SWGs. Though the cost and adoption issues are critical, potential benefits of SWGs such as efficient water conservation and distribution sustain the development of SWGs around the world. The review finds that the keys to success are the new regulations concerning data access and ownership to solve problems of security and privacy; consumer literacy to accept and use SWGs; active private sector involvement to coordinate SWG development; government-funded pilot projects and trial centers; and integration with sustainable water management.

  6. Barriers and Solutions to Smart Water Grid Development.

    PubMed

    Cheong, So-Min; Choi, Gye-Woon; Lee, Ho-Sun

    2016-03-01

    This limited review of smart water grid (SWG) development, challenges, and solutions provides an initial assessment of early attempts at operating SWGs. Though the cost and adoption issues are critical, potential benefits of SWGs such as efficient water conservation and distribution sustain the development of SWGs around the world. The review finds that the keys to success are the new regulations concerning data access and ownership to solve problems of security and privacy; consumer literacy to accept and use SWGs; active private sector involvement to coordinate SWG development; government-funded pilot projects and trial centers; and integration with sustainable water management. PMID:26608885

  7. Barriers and Solutions to Smart Water Grid Development

    NASA Astrophysics Data System (ADS)

    Cheong, So-Min; Choi, Gye-Woon; Lee, Ho-Sun

    2016-03-01

    This limited review of smart water grid (SWG) development, challenges, and solutions provides an initial assessment of early attempts at operating SWGs. Though the cost and adoption issues are critical, potential benefits of SWGs such as efficient water conservation and distribution sustain the development of SWGs around the world. The review finds that the keys to success are the new regulations concerning data access and ownership to solve problems of security and privacy; consumer literacy to accept and use SWGs; active private sector involvement to coordinate SWG development; government-funded pilot projects and trial centers; and integration with sustainable water management.

  8. Analytical steady-state solutions for water-limited cropping systems using saline irrigation water

    NASA Astrophysics Data System (ADS)

    Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.

    2014-12-01

    Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess advantages over available alternatives, including: (i) the solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.

  9. Semen coagulum liquefaction, sperm activation and cryopreservation of capuchin monkey (Cebus apella) semen in coconut water solution (CWS) and TES-TRIS.

    PubMed

    Oliveira, Karol G; Miranda, Stefania A; Leão, Danuza L; Brito, Adriel B; Santos, Regiane R; Domingues, Sheyla F S

    2011-01-01

    The objectives of the present study were to test the effect of coconut water solution and TES-TRIS on the seminal coagulum liquefaction, sperm activation in fresh diluted semen, and on the cryopreservation of semen from capuchin monkeys (Cebus apella). Semen was collected from six males by electro-ejaculation, diluted in TES-TRIS or coconut water solution (CWS), and incubated at 35°C until the coagulated fraction of the semen was completely liquefied. In the experiment I, after liquefaction, samples were diluted in TES-TRIS or CWS, plus 6 and 10mM/mL of caffeine. Sperm motility and vigor were evaluated during 5h. For experiment II, after liquefaction, semen samples were extended in TES-TRIS (3.5% glycerol in the final solution) or CWS (2.5% glycerol in the final solution), cryopreserved and stored in liquid nitrogen for 1 week. The seminal coagulum was liquefied in (mean±SDM) 4.5±1.7 and 2.8±1.1h in TES-TRIS and CWS, respectively. Sperm were motile in TES-TRIS and CWS for 5.0±1.4 and 1.0±0.5h, respectively. The mean motility in this period was 38±22% (TES-TRIS) and 22.0±16.0 (CWS). Motility increased after caffeine addition only in samples diluted in CWS containing 6mM (22.5±16.0) or 10mM (28.0±19.0) caffeine. Post-thaw live sperm percentage was 26.2% in TES-TRIS and 13.2% in CWS. For cryopreservation of semen from C. apella TES-TRIS (3.5% glycerol) was more appropriate than CWS (2.5% glycerol). CWS+caffeine potentially increase sperm motility and may be useful in artificial insemination of fresh diluted semen.

  10. Isothermal dehydration of thin films of water and sugar solutions

    SciTech Connect

    Heyd, R.; Rampino, A.; Bellich, B.; Elisei, E.; Cesàro, A.; Saboungi, M.-L.

    2014-03-28

    The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar solutions is investigated with a dual experimental and theoretical approach. A nanoporous paper disk with a homogeneous internal structure was used as a substrate. This experimental set-up makes it possible to gather thermodynamic data under well-defined conditions, develop a numerical model, and extract needed information about the dehydration process, in particular the water activity. It is found that the temperature evolution of the pure water film is not strictly isothermal during the drying process, possibly due to the influence of water diffusion through the cellulose web of the substrate. The role of sugar is clearly detectable and its influence on the dehydration process can be identified. At the end of the drying process, trehalose molecules slow down the diffusion of water molecules through the substrate in a more pronounced way than do the glucose molecules.

  11. Emerging solutions to the water challenges of an urbanizing world.

    PubMed

    Larsen, Tove A; Hoffmann, Sabine; Lüthi, Christoph; Truffer, Bernhard; Maurer, Max

    2016-05-20

    The top priorities for urban water sustainability include the provision of safe drinking water, wastewater handling for public health, and protection against flooding. However, rapidly aging infrastructure, population growth, and increasing urbanization call into question current urban water management strategies, especially in the fast-growing urban areas in Asia and Africa. We review innovative approaches in urban water management with the potential to provide locally adapted, resource-efficient alternative solutions. Promising examples include new concepts for stormwater drainage, increased water productivity, distributed or on-site treatment of wastewater, source separation of human waste, and institutional and organizational reforms. We conclude that there is an urgent need for major transdisciplinary efforts in research, policy, and practice to develop alternatives with implications for cities and aquatic ecosystems alike. PMID:27199414

  12. Emerging solutions to the water challenges of an urbanizing world.

    PubMed

    Larsen, Tove A; Hoffmann, Sabine; Lüthi, Christoph; Truffer, Bernhard; Maurer, Max

    2016-05-20

    The top priorities for urban water sustainability include the provision of safe drinking water, wastewater handling for public health, and protection against flooding. However, rapidly aging infrastructure, population growth, and increasing urbanization call into question current urban water management strategies, especially in the fast-growing urban areas in Asia and Africa. We review innovative approaches in urban water management with the potential to provide locally adapted, resource-efficient alternative solutions. Promising examples include new concepts for stormwater drainage, increased water productivity, distributed or on-site treatment of wastewater, source separation of human waste, and institutional and organizational reforms. We conclude that there is an urgent need for major transdisciplinary efforts in research, policy, and practice to develop alternatives with implications for cities and aquatic ecosystems alike.

  13. Isothermal dehydration of thin films of water and sugar solutions.

    PubMed

    Heyd, R; Rampino, A; Bellich, B; Elisei, E; Cesàro, A; Saboungi, M-L

    2014-03-28

    The process of quasi-isothermal dehydration of thin films of pure water and aqueous sugar solutions is investigated with a dual experimental and theoretical approach. A nanoporous paper disk with a homogeneous internal structure was used as a substrate. This experimental set-up makes it possible to gather thermodynamic data under well-defined conditions, develop a numerical model, and extract needed information about the dehydration process, in particular the water activity. It is found that the temperature evolution of the pure water film is not strictly isothermal during the drying process, possibly due to the influence of water diffusion through the cellulose web of the substrate. The role of sugar is clearly detectable and its influence on the dehydration process can be identified. At the end of the drying process, trehalose molecules slow down the diffusion of water molecules through the substrate in a more pronounced way than do the glucose molecules.

  14. Conformational equilibria of alkanes in aqueous solution: relationship to water structure near hydrophobic solutes.

    PubMed Central

    Ashbaugh, H S; Garde, S; Hummer, G; Kaler, E W; Paulaitis, M E

    1999-01-01

    Conformational free energies of butane, pentane, and hexane in water are calculated from molecular simulations with explicit waters and from a simple molecular theory in which the local hydration structure is estimated based on a proximity approximation. This proximity approximation uses only the two nearest carbon atoms on the alkane to predict the local water density at a given point in space. Conformational free energies of hydration are subsequently calculated using a free energy perturbation method. Quantitative agreement is found between the free energies obtained from simulations and theory. Moreover, free energy calculations using this proximity approximation are approximately four orders of magnitude faster than those based on explicit water simulations. Our results demonstrate the accuracy and utility of the proximity approximation for predicting water structure as the basis for a quantitative description of n-alkane conformational equilibria in water. In addition, the proximity approximation provides a molecular foundation for extending predictions of water structure and hydration thermodynamic properties of simple hydrophobic solutes to larger clusters or assemblies of hydrophobic solutes. PMID:10423414

  15. Generation of acids from mine waste: Oxidative leaching of pyrrhotite in dilute H 2SO 4 solutions at pH 3.0

    NASA Astrophysics Data System (ADS)

    Pratt, A. R.; Nesbitt, H. W.; muir, I. J.

    1994-12-01

    Pyrrhotite (Fe 7S 8) grains 3 × 3 × 6 mm were reacted in solutions of H 2SO 4 (pH 3.0) for eight hours and analyzed using secondary electron microscopy (SEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). SEM images of reacted surfaces display an array of reaction textures, which are interpreted to represent a five-stage (T1-T5) paragenetic alteration sequence. Leached pyrrhotite surfaces are initially featureless (T1 texture). Surfaces leached more extensively develop a mottled felty texture (T2). Subsequent drying of reacted surfaces causes dehydration, producing cracked, tiled surfaces (T3 textures). Prolonged drying intensifies the effects of desiccation, producing rubbly (T4) textures. The rubble is readily spalled, exposing smooth underlayers (T5 textures). AES and XPS data collected from T1 through T4 textured surfaces indicate primarily Fe-oxyhydroxide reaction products. AES depth profiles show that S varies antipathetically with oxygen. AES analysis of T5 textured surfaces (underlayer exposed by spalling) detect only Fe and S, with S significantly enriched over Fe. XPS and modelled AES data show T5 textured regions are mainly ferric iron bonded to disulphide and/or polysulphide species. The accumulation of S in the underlayer is accomplished by preferential migration of Fe to the overlying oxyhydroxide layer to the pyrrhotite surface, thus, promoting spallation. Spalling of Fe(III)-oxyhydroxides is promoted in waste rock dumps and tailings situated above the water table by periodic wetting, drying and desiccation of the oxyhydroxide layer. These circumstances may, in turn, lead to high concentrations of suspended Fe-oxyhydroxide in tailings ponds during flooding and in ponds where there are dramatic seasonal overturns of lake or pond water. Exposure by spalling of S-rich sublayers to aqueous solutions is an effective means for producing sulphuric acid-rich mine waste runoff and of producing periodic flushes of sulphuric

  16. Optimizing remediation monitoring by evaluating depth-specific water velocity in a polluted aquifer: The borehole dilution test applied to multilevel samplers, a case study at the AGTROL industrial site, Bordeaux (France)

    NASA Astrophysics Data System (ADS)

    Bourg, A. C.; Kedziorek, M. A.; Dupuy, A.

    2009-12-01

    For contaminant plumes in hydraulically stratified aquifers, identifying depths of preferential groundwater flow is essential because this is where the actual transport takes place and therefore might be where dedicated monitoring should be done. We present here a method (adapted from the single borehole dilution tracer test) in which a volume of tracer solution is injected into a port of a multi-level sampler at a given depth and small volumes of water are retrieved through the same port at specific times. The correlation between tracer concentration and time is used to calculate the renewal time of a volume of water in the aquifer and estimate pore velocity (or specific discharge). The method is tested on a fill phreatic aquifer in Southwestern France, polluted by sulfuric acid and copper (pH as low as 1 and dissolved sulfate and copper as high as 45 and 30 g/L, respectively, near the source of the contaminant plume). Core sample analyses indicate that copper is trapped on the edge of the plume as a solid at specific depths that correspond to carbonate depletion (water pH increasing due to pH buffer). Groundwater flows more rapidly at these depths. As a result, these aquifer layers are not only permeable and water transmittive but also geochemically reactive. Natural attenuation should therefore be monitored at these depths.

  17. Evaporation kinetics of acetic acid-water solutions

    NASA Astrophysics Data System (ADS)

    Duffey, K.; Wong, N.; Saykally, R.; Cohen, R. C.

    2012-12-01

    The transport of water molecules across vapor-liquid interfaces in the atmosphere is a crucial step in the formation and evolution of cloud droplets. Despite decades of study, the effects of solutes on the mechanism and rate of evaporation and condensation remain poorly characterized. The present work aims to determine the effect of atmospherically-relevant solutes on the evaporation rate of water. In our experiments, we create a train of micron-sized droplets and measure their temperature via Raman thermometry as they undergo evaporation without condensation. Analysis of the cooling rate yields the evaporation coefficient (γ). Previous work has shown that inorganic salts have little effect on γ, with surface-adsorbing anions causing a slight reduction in the coefficient from that measured for pure water. Organic acids are ubiquitous in aqueous aerosol and have been shown to disrupt the surface structure of water. Here we describe measurements of the evaporation rate of acetic acid solutions, showing that acetic acid reduces γ to a larger extent than inorganic ions, and that γ decreases with increasing acetic acid concentration.

  18. Photodegradation of triazine herbicides in aqueous solutions and natural waters.

    PubMed

    Evgenidou, E; Fytianos, K

    2002-10-23

    The photodegradation of three triazines, atrazine, simazine, and prometryn, in aqueous solutions and natural waters using UV radiation (lambda > 290 nm) has been studied. Experimental results showed that the dark reactions were negligible. The rate of photodecomposition in aqueous solutions depends on the nature of the triazines and follows first-order kinetics. In the case of the use of hydrogen peroxide and UV radiation, a synergistic effect was observed. The number of photodegradation products detected, using FIA/MS and FIA/MS/MS techniques, suggests the existence of various degradation routes resulting in complex and interconnected pathways. PMID:12381128

  19. THE VAPOUR PRESSURES OF AQUEOUS SOLUTIONS WITH SPECIAL REFERENCE TO THE PROBLEM OF THE STATE OF WATER IN BIOLOGICAL FLUIDS.

    PubMed

    Grollman, A

    1931-05-20

    DATA FOR THE DEPRESSION OF VAPOUR PRESSURE ARE PRESENTED FOR THE FOLLOWING AQUEOUS SOLUTIONS: NaCl (0.03 to 0.1 molar), KCl (0.03 to 0.1 molar), urea (0.05 to 0.5 molar), sucrose (0.05 to 0.10 molar), lactic and succinic acids, creatine, CaCl(2) (0.05 molar), and mixtures of these substances with one another and with certain other solutions (gelatin, gum acacia, sea water, LiCl, etc.). The relation of the depression of vapour pressure of a mixed solution to that of solutions of the individual constituents was investigated in order to ascertain to what extent such studies may be used for the determination of the degree of hydration, or of the state of water, in solutions. Organic substances (urea, sucrose, etc.) showed anomalous results which were markedly affected and unpredictable in mixed solutions. They are, therefore, unsuited for the study of water binding. In the case of solutions of inorganic substances-LiCl and CaCl(2)-the principle of the additive nature of colligative properties is also only approximately true-except perhaps in very dilute solutions. The limitations of the colligative method for determining the degree of hydration have been defined in accord with the above findings. Studies of the vapour pressures of mixtures of gelatin or gum acacia with NaCl or KCl demonstrated that hydration in gelatin is relatively small at pH = 7 and undetectable in gum acacia solutions. The view, therefore, that hydrophilic colloids are strongly hydrated has not been substantiated. The passage from the sol to the gel state also was not accompanied in gelatin or in blood by any appreciable change in the degree of hydration of the hydrophilic colloids present in these substances.

  20. Evaluation of a new most-probable-number (MPN) dilution plate method for the enumeration of Escherichia coli in water samples.

    PubMed

    Kodaka, Hidemasa; Saito, Mikako; Matsuoka, Hideaki

    2009-09-01

    The purpose of this study was to evaluate the most-probable-number dilution plate (MPN plate) method developed for the enumeration of Escherichia coil in water samples. Sterilized water was inoculated with E. coli ATCC 11775 to give between 2-1600 MPN/100 ml. The MPN was determined for both the MPN plate and 5-tube methods from the MPN table. The average of the natural logarithm (In) MPN with standard deviations in 95 samples was 4.26 +/- 1.48 by the 5-tube-method and 4.18 +/- 1.45 by the MPN plate method. The correlation coefficient was 0.96. These results were not significantly different according to the paired t-test (p > 0.05).

  1. Solvation enthalpies of hydrocarbons in water-alcohol solutions

    SciTech Connect

    Antonova, O.A.; Batov, D.V.; Korolev, V.P.

    1994-03-20

    It was found that the enthalpies of solvation of alkanes and xenon in water-alcohol mixtures vary, following a parabolic law relative to the density of the cohesion energy of a mixed solvent ({rho}). The general relationships were obtained for calculation of the solvation enthalpy of alkanes as a function of {rho} of the mixture and of the size of the solute particles. 14 refs., 6 figs.

  2. Model of solute and water movement in the kidney.

    PubMed

    Stephenson, J L; Mejia, R; Tewarson, R P

    1976-01-01

    Finite difference equations describing salt and water movement in a model of the mammalian kidney have been solved numerically by an extension of the Newton-Raphson method used for the medullary counterflow system. The method permits both steady-state and transient solutions. It has been possible to simulate behavior of the whole kidney as a function of hydrostatic pressures in renal artery, vein, and pelvis; protein and other solute concentrations in arterial blood; and phenomenological equations describing transport of solute and water across nephron and capillary walls. With the model it has been possible to compute concentrations, flows, and hydrostatic pressures in the various nephron segments and in cortical and medullary capillaries and interstitium. In a general way, calculations on the model have met intuitive expectations. In addition, they have reemphasized the critical dependence of renal function on the hydraulic and solute permeabilities of glomerular, postglomerular, and medullary capillaries. These studies provide additional support for our thesis that the functional unit of the kidney is not the single nephron, but a nephrovascular unit consisting of a group of nephrons and their tightly coupled vasculature.

  3. Biogeochemical impact of a dilution plume (Rhone River) on coastal sediments - comparison between a surface water survey (1996-2000) and sediment composition

    NASA Astrophysics Data System (ADS)

    Alliot, E.; Younes a, , W. A. N.; Romano, J.-C.; Rebouillon, P.; Massé, H.

    2003-05-01

    The Rhone River is the major source of nutrients and particulate matter to the Mediterranean basin. Its influence on coastal sediments was investigated by searching for the presence of continental markers. The composition of coastal sediments situated in the area influenced by the Rhone River inputs was compared with surface water salinity time-series records (five years bi-monthly survey). Sediment samples were analysed for grain-size, total and organic carbon and nitrogen, pigments, trace metals, carbohydrates, protein and lipid content. Comparisons show that changes in sediments are associated with the mean extension of the dilution plume of the river. The organic carbon content of sediments does not exhibit spatial changes related to the variations in the overlying water column. A large amount of inorganic carbon is discharged into the sea by the river and results in dilution of the organic carbon in the deposited material. The CaCO 3 fraction of the total carbon of sediments is influenced by the river inputs with lower values in front of the river mouth. Changes in the composition of organic matter are linked with the inputs of the Rhone River and associated with variations of concentrations of the chlorophyll b as a marker of the terrestrial origin of the organic matter. Chlorophyll b content of sediments showed statistically significant negative correlation with the five-year bi-monthly mean surface salinity values ( slope=-0.0233, R2=0.9437, n=22, p<0.001). Other parameters such as Mn content of sediments exhibit significant positive correlation with chlorophyll b and negative correlation with mean surface water salinity. Labile carbon fraction (carbohydrates, lipids and protein) shows significant correlation both with chlorophyll b and salinity. In the area influenced by the Rhone River dilution plume, there is enrichment in labile organic matter. The amounts of insoluble carbohydrates and phaeopigments suggest that this enrichment is mainly due to

  4. Modeling the movement and equilibrium of water in the body of ruminants in relation to estimating body composition by deuterium oxide dilution

    SciTech Connect

    Arnold, R.N.

    1986-01-01

    Deuterium oxide (D/sub 2/O) dilution was evaluated for use in estimating body composition of ruminants. Empty body composition of cattle could not be accurately estimated by two- or three-compartment models when solved on the basis of clearance of D/sub 2/O from blood. A 29-compartment blood-flow model was developed from measured blood flow rates and water volumes of tissues of sheep. The rates of equilibration of water in tissues that were simulated by the blood-flow model were much faster than actual rates measured in sheep and cattle. The incorporation of diffusion hindrances for movement of water into tissues enabled the blood flow model to simulate the measured equilibration rates in tissues, but the values of the diffusion coefficients were different for each tissue. The D/sub 2/O-disappearance curve for blood simulated by the blood-flow model with diffusion limitations was comprised for four exponential components. The tissues and gastrointestinal tract contents were placed into five groups based upon the rate of equilibration. Water in the organs of the body equilibrated with water in blood within 3 min. Water in visceral fat, head, and some of the gastrointestinal tract tissues equilibrated within 8 to 16 min. Water in skeletal muscle, fat, and bone and the contents of some segments of the gastrointestinal tract equilibrated within 30 to 36 min. Water in the tissues and contents of the cecum and upper-large intestine equilibrated within 160 to 200 min. Water in ruminal tissue and contents equilibrated within 480 min.

  5. Impact of water table fluctuations on water flow and solute transport in 1D column systems

    NASA Astrophysics Data System (ADS)

    Rühle, F.; Stumpp, C.

    2012-04-01

    Although hydrological processes and mass fluxes in the unsaturated and saturated zone have been well studied separately, little is known about transition processes between these zones. Since the transition zone is dynamic and varies spatially and temporally with fluctuations of the water table, water flow and solute transport are believed to vary dynamically, too. This may influence the transport and fate of dissolved contaminants and consequently the quality of groundwater. In order to protect and maintain drinking water resources, improved understanding about hydrological processes at the dynamic interface between the unsaturated and saturated zone is needed. The objective of this study was to investigate the impact of water table fluctuations on one-dimensional vertical flow and solute transport in laboratory column systems. Therefore, two flow-through columns were constantly irrigated with groundwater at an infiltration rate of 4.7 cm/d. In one column the water table was kept statically fixed in the middle, in the other column the water table was continually fluctuated by regularly raising and lowering the outflow tube. Several multi-tracer experiments were conducted and compared injecting the tracers bromide, deuterium and 18-oxygen at different water levels. Data modelling was performed with a lumped parameter model to simulate the hydrological fluxes. Our results showed that at static water table and similar water fluxes in both columns, structural heterogeneities due to packing lead to differences in solute transport, e.g. different dispersivity. Tracer breakthrough curves were well simulated with the lumped parameter model indicating that the systems were at steady state. When the water table was fluctuated small differences in solute transport were observed. Even with a fluctuating water table the lumped parameter model yielded high modelling accuracy and indicated that under certain hydrological conditions water table fluctuations lead to slightly

  6. Quantifying groundwater-surface water interactions in a proglacial moraine using heat and solute tracers

    NASA Astrophysics Data System (ADS)

    Langston, Gregory; Hayashi, Masaki; Roy, James W.

    2013-09-01

    Recent studies in mountain environments have indicated that groundwater represents a major component of the water balance of alpine streams and lakes. However, the scarcity of information on the hydraulic properties of geological materials in alpine environments presents a major obstacle to understanding the response of these watersheds to hydrological inputs and their future variability. The information is particularly limited for talus and proglacial moraine, where rugged topography prohibits the installation of groundwater monitoring wells. Observation of groundwater-surface water interaction provides a useful tool for studying groundwater in these challenging environments. Here we present a unique experiment using a tarn (i.e., pond on proglacial moraine) in a partially glaciated watershed in the Canadian Rockies as a surrogate for a groundwater monitoring well. A chloride dilution test and detailed energy balance monitoring were simultaneously conducted to quantify the groundwater-surface water interactions. The water balance of the tarn was dominated by groundwater inflow and outflow, ranging between 70 and 720 m3 d-1, while the volume of the water in the tarn fluctuated between 140 and 620 m3. Comparing the observed flow rates with a semianalytical solution of groundwater interactions with a flow-through pond, the hydraulic conductivity of the proglacial moraine is estimated to be in the order of 10-3 m s-1, which provides one of the very few measurements of large-scale hydraulic conductivity of proglacial moraine. The study demonstrates a useful application of mass and energy balance measurements in rugged environments and provides the essential information for advancing our understanding of alpine groundwater hydrology.

  7. Dilution and the elusive baseline.

    PubMed

    Likens, Gene E; Buso, Donald C

    2012-04-17

    Knowledge of baseline conditions is critical for evaluating quantitatively the effect of human activities on environmental conditions, such as the impact of acid deposition. Efforts to restore ecosystems to prior, "pristine" condition require restoration targets, often based on some presumed or unknown baseline condition. Here, we show that rapid and relentless dilution of surface water chemistry is occurring in the White Mountains of New Hampshire, following decades of acid deposition. Extrapolating measured linear trends using a unique data set of up to 47 years, suggest that both precipitation and streamwater chemistry (r(2) >0.84 since 1985) in the Hubbard Brook Experimental Forest (HBEF) will approximate demineralized water within one to three decades. Because such dilute chemistry is unrealistic for surface waters, theoretical baseline compositions have been calculated for precipitation and streamwater: electrical conductivity of 3 and 5 μS/cm, base cation concentrations of 7 and 39 μeq/liter, acid-neutralizing capacity values of <1 and 14 μeq/liter, respectively; and pH 5.5 for both. Significantly large and rapid dilution of surface waters to values even more dilute than proposed for Pre-Industrial Revolution (PIR) conditions has important ecological, biogeochemical and water resource management implications, such as for the success of early reproductive stages of aquatic organisms.

  8. Dilution and the elusive baseline.

    PubMed

    Likens, Gene E; Buso, Donald C

    2012-04-17

    Knowledge of baseline conditions is critical for evaluating quantitatively the effect of human activities on environmental conditions, such as the impact of acid deposition. Efforts to restore ecosystems to prior, "pristine" condition require restoration targets, often based on some presumed or unknown baseline condition. Here, we show that rapid and relentless dilution of surface water chemistry is occurring in the White Mountains of New Hampshire, following decades of acid deposition. Extrapolating measured linear trends using a unique data set of up to 47 years, suggest that both precipitation and streamwater chemistry (r(2) >0.84 since 1985) in the Hubbard Brook Experimental Forest (HBEF) will approximate demineralized water within one to three decades. Because such dilute chemistry is unrealistic for surface waters, theoretical baseline compositions have been calculated for precipitation and streamwater: electrical conductivity of 3 and 5 μS/cm, base cation concentrations of 7 and 39 μeq/liter, acid-neutralizing capacity values of <1 and 14 μeq/liter, respectively; and pH 5.5 for both. Significantly large and rapid dilution of surface waters to values even more dilute than proposed for Pre-Industrial Revolution (PIR) conditions has important ecological, biogeochemical and water resource management implications, such as for the success of early reproductive stages of aquatic organisms. PMID:22455659

  9. Systemic solutions for multi-benefit water and environmental management.

    PubMed

    Everard, Mark; McInnes, Robert

    2013-09-01

    The environmental and financial costs of inputs to, and unintended consequences arising from narrow consideration of outputs from, water and environmental management technologies highlight the need for low-input solutions that optimise outcomes across multiple ecosystem services. Case studies examining the inputs and outputs associated with several ecosystem-based water and environmental management technologies reveal a range from those that differ little from conventional electro-mechanical engineering techniques through methods, such as integrated constructed wetlands (ICWs), designed explicitly as low-input systems optimising ecosystem service outcomes. All techniques present opportunities for further optimisation of outputs, and hence for greater cumulative public value. We define 'systemic solutions' as "…low-input technologies using natural processes to optimise benefits across the spectrum of ecosystem services and their beneficiaries". They contribute to sustainable development by averting unintended negative impacts and optimising benefits to all ecosystem service beneficiaries, increasing net economic value. Legacy legislation addressing issues in a fragmented way, associated 'ring-fenced' budgets and established management assumptions represent obstacles to implementing 'systemic solutions'. However, flexible implementation of legacy regulations recognising their primary purpose, rather than slavish adherence to detailed sub-clauses, may achieve greater overall public benefit through optimisation of outcomes across ecosystem services. Systemic solutions are not a panacea if applied merely as 'downstream' fixes, but are part of, and a means to accelerate, broader culture change towards more sustainable practice. This necessarily entails connecting a wider network of interests in the formulation and design of mutually-beneficial systemic solutions, including for example spatial planners, engineers, regulators, managers, farming and other businesses, and

  10. Engineering solutions for polymer composites solar water heaters production

    NASA Astrophysics Data System (ADS)

    Frid, S. E.; Arsatov, A. V.; Oshchepkov, M. Yu.

    2016-06-01

    Analysis of engineering solutions aimed at a considerable decrease of solar water heaters cost via the use of polymer composites in heaters construction and solar collector and heat storage integration into a single device representing an integrated unit results are considered. Possibilities of creating solar water heaters of only three components and changing welding, soldering, mechanical treatment, and assembly of a complicate construction for large components molding of polymer composites and their gluing are demonstrated. Materials of unit components and engineering solutions for their manufacturing are analyzed with consideration for construction requirements of solar water heaters. Optimal materials are fiber glass and carbon-filled plastics based on hot-cure thermosets, and an optimal molding technology is hot molding. It is necessary to manufacture the absorbing panel as corrugated and to use a special paint as its selective coating. Parameters of the unit have been optimized by calculation. Developed two-dimensional numerical model of the unit demonstrates good agreement with the experiment. Optimal ratio of daily load to receiving surface area of a solar water heater operating on a clear summer day in the midland of Russia is 130‒150 L/m2. Storage tank volume and load schedule have a slight effect on solar water heater output. A thermal insulation layer of 35‒40 mm is sufficient to provide an efficient thermal insulation of the back and side walls. An experimental model layout representing a solar water heater prototype of a prime cost of 70‒90/(m2 receiving surface) has been developed for a manufacturing volume of no less than 5000 pieces per year.

  11. Utilising integrated urban water management to assess the viability of decentralised water solutions.

    PubMed

    Burn, Stewart; Maheepala, Shiroma; Sharma, Ashok

    2012-01-01

    Cities worldwide are challenged by a number of urban water issues associated with climate change, population growth and the associated water scarcity, wastewater flows and stormwater run-off. To address these problems decentralised solutions are increasingly being considered by water authorities, and integrated urban water management (IUWM) has emerged as a potential solution to most of these urban water challenges, and as the key to providing solutions incorporating decentralised concepts at a city wide scale. To incorporate decentralised options, there is a need to understand their performance and their impact on a city's total water cycle under alternative water and land management options. This includes changes to flow, nutrient and sediment regimes, energy use, greenhouse gas emissions, and the impacts on rivers, aquifers and estuaries. Application of the IUWM approach to large cities demands revisiting the fundamental role of water system design in sustainable city development. This paper uses the extended urban metabolism model (EUMM) to expand a logical definition for the aims of IUWM, and discusses the role of decentralised systems in IUWM and how IUWM principles can be incorporated into urban water planning.

  12. Impact of water table fluctuations on water flow and solute transport in different porous media

    NASA Astrophysics Data System (ADS)

    Rühle, Franziska; Zentner, Nadine; Stumpp, Christine

    2013-04-01

    The interface between saturated and unsaturated zone is dynamic and varies spatially and temporally resulting in fluctuations of the water table. Still, little is known about transport processes under transient flow conditions at this interface and how the processes are affected by altering the water table. In order to understand transport and fate of dissolved contaminants into the groundwater and consequently the quality of groundwater, improved understanding about hydrological processes at the dynamic interface between unsaturated and saturated zone is needed. The objective of this study was to investigate the impact of water table fluctuations on one-dimensional vertical flow and solute transport in different sediments. Therefore, flow-through columns (length=50cm, diameter=9cm), filled with glass beads of different grain sizes (smaller=0.4-0.6mm, coarser=1.0-1.5mm), were constantly irrigated at 12 cm/d. Several multi-tracer experiments were conducted with a statically fixed water table and compared to experiments where the water table was fluctuated in upward and downward direction. Data modeling was performed with a lumped parameter model to simulate hydrological fluxes and to determine transport parameters. Our results showed that most tracer breakthrough curves were well simulated indicating that the systems were at steady state. The results showed that under certain hydrological conditions water table fluctuations lead to increased dispersivity. It is suggested that a falling water table can cause increased spreading when the decline is faster than the water flux resulting in a more extensive solute distribution over depth. Further, it was observed that a rising water table can cause higher tracer spreading due to diffusive solute exchange in coarse sediments with immobile water regions. In conclusion, spatial and temporal variability of the interface between vadose zone and groundwater contribute to spreading of solutes and therefore have to be considered

  13. Tracing the flow rate and mixing ratio of the Changjiang diluted water in the northwestern Pacific marginal seas using radium isotopes

    NASA Astrophysics Data System (ADS)

    Lee, Hojun; Kim, Guebuem; Kim, Jeonghyun; Park, Gwanserk; Song, Ki-Hoon

    2014-07-01

    We measured Ra isotopes (223Ra and 228Ra) in surface seawater of the northwestern Pacific marginal seas to trace the flow rate and mixing of the Changjiang diluted water (CDW) in the summer of 2012. Based on the horizontal distribution of 223Ra activities, the arrival time of CDW from the river mouth to 450 km offshore northeast was estimated to be 20-35 days, which is similar to that determined in previous studies. Moreover, we successfully calculated the relative contribution of CDW at each sampling station using a salinity and 228Ra diagram. Using this unique method, we found that the relative contribution of CDW was more than 30% in most surface seawaters of the northern East China Sea, the Yellow Sea, and the southern sea off Korea. Our results suggest that CDW is of high significance in the biogeochemistry of surface seawater of these northwestern Pacific marginal seas during the summer monsoon period.

  14. Water flow and solute transport in floating fen root mats

    NASA Astrophysics Data System (ADS)

    Stofberg, Sija F.; EATM van der Zee, Sjoerd

    2015-04-01

    be very similar and likely functionally related. Our experimental field data were used for modelling water flow and solute transport in floating fens, using HYDRUS 2D. Fluctuations of surface water and root mat, as well as geometry and unsaturated zone parameters can have a major influence on groundwater fluctuations and the exchange between rain and surface water and the water in the root mats. In combination with the duration of salt pulses in surface water, and sensitivity of fen plants to salinity (Stofberg et al. 2014, submitted), risks for rare plants can be anticipated.

  15. Near-Infrared Studies of Glucose and Sucrose in Aqueous Solutions: Water Displacement Effect and Red Shift in Water Absorption from Water-Solute Interaction

    NASA Astrophysics Data System (ADS)

    Jung, Youngeui; Hwang, Jungseek

    2013-02-01

    We use near infrared spectroscopy to obtain concentration dependent glucose absorption spectra in their aqueous solutions in the near-infrared range (3800 - 7500 cm^{-1}). We introduce a new method to obtain reliable glucose absorption bands from aqueous glucose solutions without measuring the water displacement coefficients of glucose separately. Additionally, we are able to extract the water displacement coefficients of glucose, and this may give a new general method using spectroscopy techniques applicable to other water soluble materials. We also observe red shifts in the absorption bands of water in the hydration shell around solute molecules, which comes from contribution of the interacting water molecules around the glucose molecules in solutions. The intensity of the red shift get larger as the concentration increases, which indicates that as the concentration increases more water molecules are involved in the interaction. However, the red shift in frequency does not seem to depend significantly on the concentration up to our highest concentration. We also performed the same measurements and analysis with sucrose instead of glucose as solute and compare.

  16. Near-infrared studies of glucose and sucrose in aqueous solutions: water displacement effect and red shift in water absorption from water-solute interaction.

    PubMed

    Jung, Youngeui; Hwang, Jungseek

    2013-02-01

    We used near infrared spectroscopy to obtain concentration dependent glucose absorption spectra in aqueous solutions in the near-infrared range (3800-7500 cm(-1)). Here we introduce a new method to obtain reliable glucose absorption bands from aqueous glucose solutions without measuring the water displacement coefficients of glucose separately. Additionally, we were able to extract the water displacement coefficients of glucose, and this may offer a new general method using spectroscopy techniques applicable to other water-soluble materials. We also observed red shifts in the absorption bands of water in the hydration shell around solute molecules, which comes from the contribution of the interacting water molecules around the glucose molecules in solutions. The intensity of the red shift gets larger as the concentration increases, which indicates that as the concentration increases more water molecules are involved in the interaction. However, the red shift in frequency does not seem to depend significantly on the concentration. We also performed the same measurements and analysis with sucrose instead of glucose as solute and compared.

  17. Plant aquaporins: multifunctional water and solute channels with expanding roles.

    PubMed

    Tyerman, S. D.; Niemietz, C. M.; Bramley, H.

    2002-02-01

    There is strong evidence that aquaporins are central components in plant water relations. Plant species possess more aquaporin genes than species from other kingdoms. According to sequence similarities, four major groups have been identified, which can be further divided into subgroups that may correspond to localization and transport selectivity. They may be involved in compatible solute distribution, gas-transfer (CO2, NH3) as well as in micronutrient uptake (boric acid). Recent advances in determining the structure of some aquaporins gives further details on the mechanism of selectivity. Gating behaviour of aquaporins is poorly understood but evidence is mounting that phosphorylation, pH, pCa and osmotic gradients can affect water channel activity. Aquaporins are enriched in zones of fast cell division and expansion, or in areas where water flow or solute flux density would be expected to be high. This includes biotrophic interfaces between plants and parasites, between plants and symbiotic bacteria or fungi, and between germinating pollen and stigma. On a cellular level aquaporin clusters have been identified in some membranes. There is also a possibility that aquaporins in the endoplasmic reticulum may function in symplasmic transport if water can flow from cell to cell via the desmotubules in plasmodesmata. Functional characterization of aquaporins in the native membrane has raised doubt about the conclusiveness of expression patterns alone and need to be conducted in parallel. The challenge will be to elucidate gating on a molecular level and cellular level and to tie those findings into plant water relations on a macroscopic scale where various flow pathways need to be considered.

  18. Water transfer as a solution to water shortage: A fix that can Backfire

    NASA Astrophysics Data System (ADS)

    Gohari, Alireza; Eslamian, Saeid; Mirchi, Ali; Abedi-Koupaei, Jahangir; Massah Bavani, Alireza; Madani, Kaveh

    2013-05-01

    Zayandeh-Rud River Basin is one of the most important basins in central Iran, which has been continually challenged by water stress during the past 60 years. Traditionally, a supply-oriented management scheme has been prescribed as a reliable solution to water shortage problems in the basin, resulting in a number of water transfer projects that have more than doubled the natural flow of the river. The main objective of this study is to evaluate the reliability of inter-basin water transfer to meet the growing water demand in Zayandeh-Rud River Basin. A system dynamics model is developed to capture the interrelationships between different sub-systems of the river basin, namely the hydrologic, socioeconomic, and agricultural sub-systems. Results from simulating a range of possible policy options for resolving water shortage problems indicate that water is essentially the development engine of the system. Therefore, supplying more water to the basin without considering the dynamics of the interrelated problems will eventually lead to increased water demand. It is demonstrated that the Zayandeh-Rud River Basin management system has characteristics of the "Fixes that Backfire" system archetype, in which inter-basin water transfer is an inadequate water management policy, causing significant unintended side-effects. A comprehensive solution to the problem includes several policy options that simultaneously control the dynamics of the system, minimizing the risk of unintended consequences. In particular, policy makers should consider minimizing agricultural water demand through changing crop patterns as an effective policy solution for the basin's water problems.

  19. Turbulent heat transfer and pressure drop characteristics of dilute water based Al2O3-Cu hybrid nanofluids.

    PubMed

    Suresh, S; Venkitaraj, K P; Hameed, M Shahul; Sarangan, J

    2014-03-01

    A study on fully developed turbulent convective heat transfer and pressure drop characteristics of Al2O3-Cu/water hybrid nanofluid flowing through a uniformly heated circular tube is presented in this paper. For this, Al2O3-Cu nanocomposite powder was synthesized in a thermo chemical route using hydrogen reduction technique and dispersed the hybrid nano powder in deionised water to form a stable hybrid nanofluid of 0.1% volume concentration. The prepared powder was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) to confirm the chemical composition, determine the particle size and study the surface morphology. Stability of the nanofluid was ensured by pH and zeta potential measurements. The average heat transfer enhancement for Al2O3-Cu/water hybrid nanofluid is 8.02% when compared to pure water. The experimental results also showed that 0.1% Al2O3-Cu/water hybrid nanofluids have slightly higher friction factor compared to 0.1% Al2O3/water nanofluid. The empirical correlations proposed for Nusselt number and friction factor were well agreed with the experimental data.

  20. Coherent anti-Stokes Raman scattering (CARS) spectra, with resonance enhancement, of cytochrome c and vitamin B12 in dilute aqueous solution.

    PubMed

    Nestor, J; Spiro, T G; Klauminzer, G

    1976-10-01

    Coherent anti-Stokes Raman scattering (CARS) spectra have been obtained for ferrocytochrome c and cyano cobalamin in aqueous solution at millimolar concentrations, using a pair of tunable dye lasers pumped by a pulsed nitrogen laser. Resonance enhancement was obtained by tuning the omega1 laser to the visible absorption bands of the samples. The spectral features correspond to those observed in the conventional resonance Raman spectra. It appears that CARS spectroscopy, with its advantageous fluorescence rejection, can be usefully applied to biological samples by exploiting resonance enhancement. While the background scattering from water is 10 times higher than that of benzene and other aromatic solvents, it is actually at the low end of the scale for most liquids. The anomalously low background of aromatic liquids is thought to result from competition by the unusually efficient stimulated Raman scattering which they display. Off-resonance spectra for both cobalamin and cytochrome c contain negative peaks, i.e., absorption bands in the background. These are interpreted as inverse Raman processes induced by the omega1 photons in the presence of the continuum provided by the background scattering. While both CARS and the inverse Raman effect are subject to resonance enhancement, the wavelength dependence of CARS is evidently steeper.

  1. Potato tuber pyrophosphate-dependent phosphofructokinase: effect of thiols and polyalcohols on its intrinsic fluorescence, oligomeric structure, and activity in dilute solutions.

    PubMed

    Podestá, F E; Moorhead, G B; Plaxton, W C

    1994-08-15

    The effect of dilution of homogeneous potato tuber pyrophosphate:fructose-6-phosphate 1-phosphotransferase (EC 2.7.1.90; PFP) on the enzyme's intrinsic fluorescence, activity, and oligomeric structure has been examined. A rapid decrease in PFP's intrinsic fluorescence occurred in response to dilution. The decay follows double-exponential kinetics and was accompanied by a reduction in catalytic activity (measured in the glycolytic direction). Gel filtration-HPLC indicated a concomitant deaggregation of the native alpha 4 beta 4 heterooctamer into the inactive free alpha- and beta-subunits, followed by random aggregation of the subunits into an inactive, high M(r) conglomerate. The addition of 2 mM dithiothreitol, 2 mM 2-mercaptoethanol, or 5% (w/v) polyethylene glycol, but not any of the substrates, Mg2+, or fructose 2,6-bisphosphate, prevented this process. When purified PFP was stored for 1 week at -20 degrees C in the presence of 50% (v/v) glycerol partial degradation of its alpha-subunit occurred. This resulted in a labile enzyme that was more susceptible to subunit dissociation. The intrinsic fluorescence of the degraded PFP could be stabilized by 5% (w/v) polyethylene glycol, but not by 2 mM dithiothreitol or 2-mercaptoethanol. It is proposed that the current assay procedures for PFP, which normally involve considerable dilution in the absence of added sulfhydryl reducing agents or polyhydroxy compounds, may underestimate the actual activity of the enzyme. This has important implications for the assessment of the functions and regulation of PFP in vivo.

  2. Thermodynamics of solution of aromatic hydrocarbons in water and in water-ethanol solutions: Comparison of some methodologies

    SciTech Connect

    Smith, R.R.; Charon, N.W.; Canady, W.J. )

    1989-07-27

    The method of Franks et al. has been applied to studies of the solubilities of both liquid and solid hydrocarbons. The temperature dependence of the solubility of toluene in water has been determined and shown to agree well with previous studies. In addition, the solubilities of n-alkyl-substituted benzenes (toluene through butylbenzene) in water have been determined at 25{degree}C; when the free energies of solution are plotted vs number of methylene groups added, a linear result was observed with a slope of about 0.71 kcal/mol per methylene group, with very little scatter being observed. The effects of added ethanol upon the free energy of solution of naphthalene at 25{degree}C have been examined by using the above-mentioned methodology of Franks et al. The results are shown to agree well with those obtained by a different methodology. The method of Franks et al is thus shown to be practical for the study of solid hydrocarbons. The long times required for equilibration of the hydrocarbon-water solutions have been shown to present no problems from contamination by microorganisms: the aromatic hydrocarbon actually exerts an inhibitory effect in this regard. The possibility of error due to adsorption of hydrocarbons from the aqueous phase to the windows of the cuvettes has been considered. Means of taking this into account (if it occurs) are outlined. This effect has been shown to be negligible or nonexistent in the case of aqueous naphthalene solutions. The methodology could find application in the study of adsorption of various substances to plastic and glass surfaces.

  3. DC diaphragm discharge in water solutions of selected organic acids

    NASA Astrophysics Data System (ADS)

    Vyhnankova, Edita J.; Hammer, Malte U.; Reuter, Stephan; Krcma, Frantisek

    2015-07-01

    Effect of four simple organic acids water solution on a DC diaphragm discharge was studied. Efficiency of the discharge was quantified by the hydrogen peroxide production determined by UV-VIS spectrometry of a H2O2 complex formed with specific titanium reagent. Automatic titration was used to study the pH behaviour after the plasma treatment. Optical emission spectroscopy overview spectra were recorded and detailed spectra of OH band and Hβ line were used to calculate the rotational temperature and comparison of the line profile (reflecting electron concentration) in the acid solutions. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  4. Serial Dilution Simulation Lab

    ERIC Educational Resources Information Center

    Keler, Cynthia; Balutis, Tabitha; Bergen, Kim; Laudenslager, Bryanna; Rubino, Deanna

    2010-01-01

    Serial dilution is often a difficult concept for students to understand. In this short dry lab exercise, students perform serial dilutions using seed beads. This exercise helps students gain skill at performing dilutions without using reagents, bacterial cultures, or viral cultures, while being able to visualize the process.

  5. Pathogenesis of solute-free water retention in experimental ascitic cirrhosis: is vasopressin the only culprit?

    PubMed

    Sansoè, Giovanni; Aragno, Manuela; Mastrocola, Raffaella; Parola, Maurizio

    2016-01-01

    Catecholamines trigger proximal tubular fluid retention and reduce renal excretion of solute-free water. In advanced cirrhosis, non-osmotic hypersecretion of vasopressin (antidiuretic hormone or ADH) is considered the cause of dilutional hyponatraemia, but ADH V2 receptor antagonists are not beneficial in long-term treatment of ascites. To test the hypothesis that water retention in experimental ascitic cirrhosis might depend primarily on adrenergic hyper-function, hormonal status, renal function and tubular free-water reabsorption (TFWR) were assessed in six groups of rats with ascitic cirrhosis: rats with cirrhosis due to 13-week CCl4 (carbon tetrachloride) administration (group G1); cirrhotic rats receiving daily diuretics (0.5 mg/kg furosemide plus 2 mg/kg K(+)-canrenoate) from the 11th to the 13th week of CCl4 (G2), diuretics associated with guanfacine oral prodrug (α2A-adrenergic receptor agonist and sympatholytic agent) at 2 (G3), 7 (G4) or 10 (G5) mg/kg, or with SSP-004240F1 (V2 receptor antagonist) at 1 mg/kg (G6). Natriuresis was lower in G1 than in G2, G4 and G6 (all P<0.05). Guanfacine, added to diuretics (i.e. G3 compared with G2), reduced serum noradrenaline from 423±22 to 211±41 ng/l (P<0.05), plasma renin activity (PRA) from 35±8 to 9±2 ng/ml/h (P<0.05) and TFWR from 45±8 to 20±6 μl/min (P<0.01). TFWR correlated with plasma aldosterone (r=0.51, P<0.01) and urinary potassium excretion (r=0.90, P<0.001). In ascitic cirrhosis, reduced volaemia, use of diuretics (especially furosemide) and adrenergic hyper-function cause tubular retention of water. Suitable doses of sympatholytic agents are effective aquaretics. PMID:26519424

  6. Cadmium determination in natural waters at the limit imposed by European legislation by isotope dilution and TiO2 solid-phase extraction.

    PubMed

    García-Ruiz, Silvia; Petrov, Ivan; Vassileva, Emilia; Quétel, Christophe R

    2011-11-01

    The cadmium content in surface water is regulated by the last European Water Framework Directive to a maximum between 0.08 and 0.25 μg L(-1) depending on the water type and hardness. Direct measurement of cadmium at this low level is not straightforward in real samples, and we hereby propose a validated method capable of addressing cadmium content below μg L(-1) level in natural water. It is based on solid-phase extraction using TiO(2) nanoparticles as solid sorbent (0.05 g packed in mini-columns) to allow the separation and preconcentration of cadmium from the sample, combined to direct isotope dilution and detection by inductively coupled plasma mass spectrometry (ID-ICP-MS). The extraction setup is miniaturised and semi-automated to reduce risks of sample contamination and improve reproducibility. Procedural blanks for the whole measurement process were 5.3 ± 2.8 ng kg(-1) (1 s) for 50 g of ultrapure water preconcentrated ten times. Experimental conditions influencing the separation (including loading pH, sample flow rates, and acid concentration in the eluent) were evaluated. With isotope dilution the Cd recovery rate does not have to be evaluated carefully. Moreover, the mathematical model associated to IDMS is known, and provides transparency for the uncertainty propagation. Our validation protocol was in agreement with guidelines of the ISO/IEC 17025 standard (chapter 5.4.5). Firstly, we assessed the experimental factors influencing the final result. Secondly, we compared the isotope ratios measured after our separation procedure to the reference values obtained with a different protocol for the digested test material IMEP-111 (mineral feed). Thirdly, we analysed the certified reference material BCR-609 (groundwater). Finally, combined uncertainties associated to our results were estimated according to ISO-GUM guidelines (typically, 3-4% k = 2 for a cadmium content of around 100 ng kg(-1)). We applied the developed method to the groundwater and wastewater

  7. Cadmium determination in natural waters at the limit imposed by European legislation by isotope dilution and TiO2 solid-phase extraction.

    PubMed

    García-Ruiz, Silvia; Petrov, Ivan; Vassileva, Emilia; Quétel, Christophe R

    2011-11-01

    The cadmium content in surface water is regulated by the last European Water Framework Directive to a maximum between 0.08 and 0.25 μg L(-1) depending on the water type and hardness. Direct measurement of cadmium at this low level is not straightforward in real samples, and we hereby propose a validated method capable of addressing cadmium content below μg L(-1) level in natural water. It is based on solid-phase extraction using TiO(2) nanoparticles as solid sorbent (0.05 g packed in mini-columns) to allow the separation and preconcentration of cadmium from the sample, combined to direct isotope dilution and detection by inductively coupled plasma mass spectrometry (ID-ICP-MS). The extraction setup is miniaturised and semi-automated to reduce risks of sample contamination and improve reproducibility. Procedural blanks for the whole measurement process were 5.3 ± 2.8 ng kg(-1) (1 s) for 50 g of ultrapure water preconcentrated ten times. Experimental conditions influencing the separation (including loading pH, sample flow rates, and acid concentration in the eluent) were evaluated. With isotope dilution the Cd recovery rate does not have to be evaluated carefully. Moreover, the mathematical model associated to IDMS is known, and provides transparency for the uncertainty propagation. Our validation protocol was in agreement with guidelines of the ISO/IEC 17025 standard (chapter 5.4.5). Firstly, we assessed the experimental factors influencing the final result. Secondly, we compared the isotope ratios measured after our separation procedure to the reference values obtained with a different protocol for the digested test material IMEP-111 (mineral feed). Thirdly, we analysed the certified reference material BCR-609 (groundwater). Finally, combined uncertainties associated to our results were estimated according to ISO-GUM guidelines (typically, 3-4% k = 2 for a cadmium content of around 100 ng kg(-1)). We applied the developed method to the groundwater and wastewater

  8. Measurement of water diffusivity in aqueous lithium bromide solution

    SciTech Connect

    Potnis, S.V.; Lenz, T.G.; Dunlop, E.H.

    1993-06-01

    The bulb apparatus developed was found to produce reliable data for measuring diffusivity for short duration. Diffusivity of water in aq. LiBr solution was found to increase from 13.2{times}10{sup {minus}10} to 16.7{times}10{sup {minus}10}m{sup 2}/s for concentration change from 0.5 to 4M and then decrease to a steady value of {approximately}6.5{times}10{sup {minus}10}m{sup 2}/s from 8 to 11 M.

  9. The ionic product of water in concentrated tetramethylammonium chloride solutions.

    PubMed

    Sipos, P; Bódi, I; May, P M; Hefter, G T

    1997-04-01

    The ionic product of water, pK(w) = - log[H(+)][OH(-)] has been determined in aqueous solutions of tetramethylammonium chloride over the concentration range of 0.1-5.5 M at 25 degrees C using high-precision glass electrode potentiometric titrations. pK(w) data relating to aqueous potassium and sodium chlorides at ionic strengths up to 5 M are markedly lower than the tetramethylammonium chloride results. These differences are almost certainly due to weak associations between potassium and (especially) sodium and hydroxide ions.

  10. Liquid chromatography/electrospray ionization/isotopic dilution mass spectrometry analysis of n-(phosphonomethyl) glycine and mass spectrometry analysis of aminomethyl phosphonic acid in environmental water and vegetation matrixes.

    PubMed

    Grey, L; Nguyen, B; Yang, P

    2001-01-01

    A liquid chromatography/electrospray/mass spectrometry (LC/ES/MS) method was developed for the analysis of glyphosate (n-phosphonomethyl glycine) and its metabolite, aminomethyl phosphonic acid (AMPA) using isotope-labelled glyphosate as a method surrogate. Optimized parameters were achieved to derivatize glyphosate and AMPA using 9-fluorenylmethyl chloroformate (FMOC-Cl) in borate buffer prior to a reversed-phase LC analysis. Method spike recovery data obtained using laboratory and real world sample matrixes indicated an excellent correlation between the recovery of the native and isotope-labelled glyphosate. Hence, the first performance-based, isotope dilution MS method with superior precision, accuracy, and data quality was developed for the analysis of glyphosate. There was, however, no observable correlation between the isotope-labelled glyphosate and AMPA. Thus, the use of this procedure for the accurate analysis of AMPA was not supported. Method detection limits established using standard U.S. Environmental Protection Agency protocol were 0.06 and 0.30 microg/L, respectively, for glyphosate and AMPA in water matrixes and 0.11 and 0.53 microg/g, respectively, in vegetation matrixes. Problems, solutions, and the method performance data related to the analysis of chlorine-treated drinking water samples are discussed. Applying this method to other environmental matrixes, e.g., soil, with minimum modifications is possible, assuring accurate, multimedia studies of glyphosate concentration in the environment and the delivery of useful multimedia information for regulatory applications.

  11. Molecular dynamics simulations of lysozyme in water/sugar solutions

    NASA Astrophysics Data System (ADS)

    Lerbret, A.; Affouard, F.; Bordat, P.; Hédoux, A.; Guinet, Y.; Descamps, M.

    2008-04-01

    Structural and dynamical properties of the solvent at the protein/solvent interface have been investigated by molecular dynamics simulations of lysozyme in trehalose, maltose and sucrose solutions. Results are discussed in the framework of the bioprotection phenomena. The analysis of the relative concentration of water oxygen atoms around lysozyme suggests that lysozyme is preferentially hydrated. When comparing the three sugars, trehalose is seen more excluded than maltose and sucrose. The preferential exclusion of sugars from the protein surface induces some differences in the behavior of trehalose and maltose, particularly at 50 and 60 wt% concentrations, that are not observed experimentally in binary sugar/mixtures. The dynamical slowing down of the solvent is suggested to mainly arise from the homogeneity of the water/sugar matrices controlled by the percolation of the sugar hydrogen bonds networks. Furthermore, lysozyme strongly increases relaxation times of solvent molecules at the protein/solvent interface.

  12. Physical knowledge of sugar water solutions: cross-cultural data.

    PubMed

    Slone, M; Dixon, J A; Bokhorst, F D

    1994-03-01

    Children's understanding of sugar water solutions may progress through universal stages: from nonpreservation to preservation to liquefaction to atomism. This claim was investigated in the current study; the claim was originally prefigured in the work of Piaget and Inhelder (1974) and more recently consolidated by Slone (1987). Our sample consisted of 270 South African children drawn from three cultural groups and ranging in age from 4 to 14 years. Children watched a demonstration in which a sugar lump was dissolved in water. Then, using structured interviews, we explored their understanding of this phenomenon. The results generally confirmed the hypothesized developmental sequence. Moreover, because the sequence was consistent across cultural groups, the claim that physical knowledge evolves through universal stages also was supported. Perhaps significantly, however, the progression of knowledge development did not unequivocally lead to the concept of atomism. Developmental implications of these findings are discussed. PMID:8021625

  13. How do water striders, Aquarius paludum, react to brackish water simulated by NaCl solutions?

    PubMed

    Kishi, Manabu; Fujisaki, Kenji; Harada, Tetsuo

    2006-01-01

    Several stages, from eggs to adults, of the water strider, Aquarius paludum (Fabricius), inhabiting fresh water are sometimes conveyed by heavy flow in the rainy or typhoon seasons in Japan to lotic brackish water in the mouth of rivers. The water striders might then respond to salinity either by remaining to wait for extensive rainfall to reduce osmotic pressure locally before reproducing ("breed here and later tactic") or by flying away to reproduce in fresh waters elsewhere ("breed elsewhere and later tactic"). All first instars died before the first molt when they were exposed to 1.75 and 3.5% NaCl solutions in a laboratory experiment. Living on 0.5 and 0.9% solutions through larval and adult stages slowed down larval growth and suppressed female reproduction. When exposed to the 0.5 and 0.9% solutions, 90 and 92% of males, respectively, showed histolysis of their flight muscles. Therefore, in brackish natural habitats, larvae and adults seem to follow the strategy "breed here and later." When water striders were exposed to 0.9% solution either just after emergence or 20 days later, females showed a higher flight propensity than those kept on fresh waters throughout, and they delayed the deposition of eggs. Therefore, when conveyed to brackish water after emergence by stream flow after heavy rain, adults seem to leave the area by flight, demonstrating the strategy "breed elsewhere and later" tactic. We conclude that water striders use alternative tactics for responding to salinity, depending on the stage of exposure.

  14. How do water striders, Aquarius paludum, react to brackish water simulated by NaCl solutions?

    NASA Astrophysics Data System (ADS)

    Kishi, Manabu; Fujisaki, Kenji; Harada, Tetsuo

    2006-01-01

    Several stages, from eggs to adults, of the water strider, Aquarius paludum (Fabricius), inhabiting fresh water are sometimes conveyed by heavy flow in the rainy or typhoon seasons in Japan to lotic brackish water in the mouth of rivers. The water striders might then respond to salinity either by remaining to wait for extensive rainfall to reduce osmotic pressure locally before reproducing (“breed here and later tactic”) or by flying away to reproduce in fresh waters elsewhere (“breed elsewhere and later tactic”). All first instars died before the first molt when they were exposed to 1.75 and 3.5% NaCl solutions in a laboratory experiment. Living on 0.5 and 0.9% solutions through larval and adult stages slowed down larval growth and suppressed female reproduction. When exposed to the 0.5 and 0.9% solutions, 90 and 92% of males, respectively, showed histolysis of their flight muscles. Therefore, in brackish natural habitats, larvae and adults seem to follow the strategy “breed here and later.” When water striders were exposed to 0.9% solution either just after emergence or 20 days later, females showed a higher flight propensity than those kept on fresh waters throughout, and they delayed the deposition of eggs. Therefore, when conveyed to brackish water after emergence by stream flow after heavy rain, adults seem to leave the area by flight, demonstrating the strategy “breed elsewhere and later” tactic. We conclude that water striders use alternative tactics for responding to salinity, depending on the stage of exposure.

  15. A nuclear magnetic resonance study of water in aggrecan solutions

    PubMed Central

    Foster, Richard J.; Damion, Robin A.; Baboolal, Thomas G.; Smye, Stephen W.; Ries, Michael E.

    2016-01-01

    Aggrecan, a highly charged macromolecule found in articular cartilage, was investigated in aqueous salt solutions with proton nuclear magnetic resonance. The longitudinal and transverse relaxation rates were determined at two different field strengths, 9.4 T and 0.5 T, for a range of temperatures and aggrecan concentrations. The diffusion coefficients of the water molecules were also measured as a function of temperature and aggrecan concentration, using a pulsed field gradient technique at 9.4 T. Assuming an Arrhenius relationship, the activation energies for the various relaxation processes and the translational motion of the water molecules were determined from temperature dependencies as a function of aggrecan concentration in the range 0–5.3% w/w. The longitudinal relaxation rate and inverse diffusion coefficient were approximately equally dependent on concentration and only increased by upto 20% from that of the salt solution. The transverse relaxation rate at high field demonstrated greatest concentration dependence, changing by an order of magnitude across the concentration range examined. We attribute this primarily to chemical exchange. Activation energies appeared to be approximately independent of aggrecan concentration, except for that of the low-field transverse relaxation rate, which decreased with concentration. PMID:27069663

  16. Bicosomes: Bicelles in Dilute Systems

    PubMed Central

    Rodríguez, Gelen; Soria, Guadalupe; Coll, Elisenda; Rubio, Laia; Barbosa-Barros, Lucyanna; López-Iglesias, Carmen; Planas, Anna M.; Estelrich, Joan; de la Maza, Alfons; López, Olga

    2010-01-01

    Abstract Bicelles are discoidal phospholipid nanostructures at high lipid concentrations. Under dilute conditions, bicelles become larger and adopt a variety of morphologies. This work proposes a strategy to preserve the discoidal morphology of bicelles in environments with high water content. Bicelles were formed in concentrated conditions and subsequently encapsulated in liposomes. Later dilution of these new structures, called bicosomes, demonstrated that lipid vesicles were able to isolate and protect bicelles entrapped inside them from the medium. Characterization of systems before and after dilution by dynamic light-scattering spectroscopy and cryo-transmission electron microscopy showed that free bicelles changed in size and morphology, whereas encapsulated bicelles remained unaltered by the effect of dilution. Free and entrapped bicelles (containing the paramagnetic contrast agent gadodiamide) were injected into rat brain lateral ventricles. Coronal and sagittal visualization was performed by magnetic resonance imaging. Whereas rats injected with free bicelles did not survive the surgery, those injected with bicosomes did, and a hyperintensity effect due to gadodiamide was observed in the cerebrospinal fluid. These results indicate that bicosomes are a good means of preserving the morphology of bicelles under dilution conditions. PMID:20643066

  17. Estimated Quantity of Water in Fractured Bedrock Units on Mt. Desert Island, and Estimated Ground-Water Use, Recharge, and Dilution of Nitrogen in Septic Waste in the Bar Harbor Area, Maine

    USGS Publications Warehouse

    Nielsen, Martha G.

    2002-01-01

    In 2002, the U.S. Geological Survey, in cooperation with the town of Bar Harbor, Maine, and the National Park Service, conducted a study to assess the quantity of water in the bedrock units underlying Mt. Desert Island, and to estimate water use, recharge, and dilution of nutrients from domestic septic systems overlying the bedrock units in several watersheds in rural Bar Harbor. Water quantity was calculated as the static volume of water in the top 600 feet of saturated thickness of the bedrock units. Volumes of water were estimated on the basis of effective fracture porosities for the five different rock types found on Mt. Desert Island. Values of porosities for the various bedrock units from the literature range more than five orders of magnitude, although the possible range in porosities for most individual rock types is on the order of three orders of magnitude. The static volume of water in the various units may range from a low of 4,000 gallons per acre for intrusive igneous rocks (primarily granites) to 20 million gallons per acre for the Cranberry Island Volcanics, but given the range in porosity estimates, these numbers can vary by orders of magnitude. Water-use data for the municipal water supply in the Town of Bar Harbor (1998-2000) indicate that residential usage averages 225 gallons per household per day. Recharge to the bedrock units in rural Bar Harbor was bracketed using low, medium, and high estimates, which were 3, 9, and 14 inches per year, respectively. Water use in 2001 was about 2.5 percent of the total estimated medium recharge (9 inches per year) in the study area. Dilution of nitrogen in septic effluent discharging to the bedrock aquifer was evaluated for the development density in 2001. On the basis of an assumed concentration of 47 mg/L of nitrogen in septic system discharge, dilution factors in populated rural Bar Harbor watersheds ranged from 4 to 151, for the housing density in 2001. Understanding that ground water in this fractured

  18. Dilution and volatilization of groundwater contaminant discharges in streams

    NASA Astrophysics Data System (ADS)

    Aisopou, Angeliki; Bjerg, Poul L.; Sonne, Anne T.; Balbarini, Nicola; Rosenberg, Louise; Binning, Philip J.

    2015-01-01

    An analytical solution to describe dilution and volatilization of a continuous groundwater contaminant plume into streams is developed for risk assessment. The location of groundwater plume discharge into the stream (discharge through the side versus bottom of the stream) and different distributions of the contaminant plume concentration (Gaussian, homogeneous or heterogeneous distribution) are considered. The model considering the plume discharged through the bank of the river, with a uniform concentration distribution was the most appropriate for risk assessment due to its simplicity and limited data requirements. The dilution and volatilization model is able to predict the entire concentration field, and thus the mixing zone, maximum concentration and fully mixed concentration in the stream. It can also be used to identify groundwater discharge zones from in-stream concentration measurement. The solution was successfully applied to published field data obtained in a large and a small Danish stream and provided valuable information on the risk posed by the groundwater contaminant plumes. The results provided by the dilution and volatilization model are very different to those obtained with existing point source models, with a distributed source leading to a larger mixing length and different concentration field. The dilution model can also provide recommendations for sampling locations and the size of impact zones in streams. This is of interest for regulators, for example when developing guidelines for the implementation of the European Water Framework Directive.

  19. Liquid chromatography with isotope-dilution mass spectrometry for determination of water-soluble vitamins in foods.

    PubMed

    Phillips, Melissa M

    2015-04-01

    Vitamins are essential for improving and maintaining human health, and the main source of vitamins is the diet. Measurement of the quantities of water-soluble vitamins in common food materials is important to understand the impact of vitamin intake on human health, and also to provide necessary information for regulators to determine adequate intakes. Liquid chromatography (LC) and mass spectrometry (MS) based methods for water-soluble vitamin analysis are abundant in the literature, but most focus on only fortified foods or dietary supplements or allow determination of only a single vitamin. In this work, a method based on LC/MS and LC/MS/MS has been developed to allow simultaneous quantitation of eight water-soluble vitamins, including multiple forms of vitamins B3 and B6, in a variety of fortified and unfortified food-matrix Standard Reference Materials (SRMs). Optimization of extraction of unbound vitamin forms and confirmation using data from external laboratories ensured accuracy in the assigned values, and addition of stable isotope labeled internal standards for each of the vitamins allowed for increased precision.

  20. Time-resolving analysis of cryotropic gelation of water/poly(vinyl alcohol) solutions via small-angle neutron scattering.

    PubMed

    Auriemma, Finizia; De Rosa, Claudio; Ricciardi, Rosa; Lo Celso, Fabrizio; Triolo, Roberto; Pipich, Vitaly

    2008-01-24

    The structural transformations occurring in initially homogeneous aqueous solutions of poly(vinyl alcohol) (PVA) through application of freezing (-13 degrees C) and thawing (20 degrees C) cycles is investigated by time resolving small-angle neutron scattering (SANS). These measurements indicate that formation of gels of complex hierarchical structure arises from occurrence of different elementary processes, involving different length and time scales. The fastest process that could be detected by our measurements during the first cryotropic treatment consists of the crystallization of the solvent. However, solvent crystallization is incomplete, and an unfrozen liquid microphase more concentrated in PVA than the initial solution is also formed. Crystallization of PVA takes place inside the unfrozen liquid microphase and is slowed down because of formation of a microgel fraction. Water crystallization takes place in the early 10 min of the treatment of the solution at subzero temperatures, and although below 0 degrees C the PVA solutions used for preparation of cryogels should be below the spinodal curve, occurrence of liquid-liquid phase separation could not be detected in our experiments. Upon thawing, ice crystals melt, and transparent gels are obtained that become opaque in approximately 200 min, due to a slow and progressive increase of the size of microheterogeneities (dilute and dense regions) imprinted during the fast freezing by the crystallization of water. During the permanence of these gels at room temperature (for hours), the presence of a high content of water (higher than 85% by mass) prevents further crystallization of PVA. Crystallization of PVA, in turn, is resumed by freezing the gels at subzero temperatures, after water crystallization and consequent formation of an unfrozen microphase. The kinetic parameters of PVA crystallization during the permanence of these gels at subzero temperatures are the same shown by PVA during the first freezing step

  1. WaterNet: The NASA water cycle solutions network - Danubian regional applications

    NASA Astrophysics Data System (ADS)

    Matthews, Dave; Brilly, Mitja; Kobold, Mira; Zagar, Mark; Houser, Paul

    2008-11-01

    WaterNet is a new international network of researchers, stakeholders, and end-users of remote sensing tools that will benefit the water resources management community. This paper provides an overview and it discusses the concept of solutions networks focusing on the WaterNet. It invites Danubian research and applications teams to join our WaterNet network. The NASA Water cycle Solutions Network's goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. Our team will develop WaterNet by engaging relevant NASA water cycle research resources and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect NASA Water cycle research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing that the European Commission and European Space Agency have also developed many related Water Research products (EWRs), we seek to learn about these and network with the EU teams to include their information in the WaterNet actionable data base and Community of Practice. WaterNet will then develop strategies to connect researchers and decision-makers via innovative communication strategies, improved user access to NASA and EU - Danubian resources, improved water cycle research community appreciation for user requirements, improved policymaker, management and stakeholder knowledge of research and application products, and improved identification of pathways for progress. Finally, WaterNet will develop relevant benchmarking and metrics, to understand the network's characteristics, to optimize its performance, and to establish sustainability. This paper provides examples of several NASA products based on remote sensing and land data assimilation systems that integrate remotely sensed and in

  2. Adaptation of sweeteners in water and in tannic acid solutions.

    PubMed

    Schiffman, S S; Pecore, S D; Booth, B J; Losee, M L; Carr, B T; Sattely-Miller, E; Graham, B G; Warwick, Z S

    1994-03-01

    Repeated exposure to a tastant often leads to a decrease in magnitude of the perceived intensity; this phenomenon is termed adaptation. The purpose of this study was to determine the degree of adaptation of the sweet response for a variety of sweeteners in water and in the presence of two levels of tannic acid. Sweetness intensity ratings were given by a trained panel for 14 sweeteners: three sugars (fructose, glucose, sucrose), two polyhydric alcohols (mannitol, sorbitol), two terpenoid glycosides (rebaudioside-A, stevioside), two dipeptide derivatives (alitame, aspartame), one sulfamate (sodium cyclamate), one protein (thaumatin), two N-sulfonyl amides (acesulfame-K, sodium saccharin), and one dihydrochalcone (neohesperidin dihydrochalcone). Panelists were given four isointense concentrations of each sweetener by itself and in the presence of two concentrations of tannic acid. Each sweetener concentration was tasted and rated four consecutive times with a 30 s interval between each taste and a 2 min interval between each concentration. Within a taste session, a series of concentrations of a given sweetener was presented in ascending order of magnitude. Adaptation was calculated as the decrease in intensity from the first to the fourth sample. The greatest adaptation in water solutions was found for acesulfame-K, Na saccharin, rebaudioside-A, and stevioside. This was followed by the dipeptide sweeteners, alitame and aspartame. The least adaptation occurred with the sugars, polyhydric alcohols, and neohesperidin dihydrochalcone. Adaptation was greater in tannic acid solutions than in water for six sweeteners. Adaptation of sweet taste may result from the desensitization of sweetener receptors analogous to the homologous desensitization found in the beta adrenergic system.

  3. UV-visible Absorption Study of the Self-association of Non-ionic Chromonic Triphenylenes TP6EOnM (n = 2, 3, 4) in Dilute Aqueous Solutions: Impact of Chain Length on Aggregation.

    PubMed

    Herbaut, Antoine; Baranoff, Etienne

    2015-01-01

    A series of triphenylenes with oligoethoxy chains of various length, TP6EOnM with n = 2, 3, 4, has been synthesised and purified by HPLC. The self-association of these disc-shaped molecules in dilute aqueous solutions (∼10(-7) to ∼4 × 10(-4) M) has been studied by UV-visible absorption spectroscopy. The free energy of association decreases as the length of the chains increases. As a result, for a given concentration, the average size of aggregate diminishes as the chain length increases. While the absorption properties of the monomer are identical for the three molecules, the extinction coefficients of solutions of the three triphenylenes at a given concentration are significantly different and are directly linked to the average size of the aggregates. The change of epsilon values upon aggregation could explain the trend generally observed with dyes for solar cells substituted with chains of increasing length showing increasing extinction coefficient values.

  4. Infrared spectroscopy of OD vibrators in minerals at natural dilution: hydroxyl groups in talc and kaolinite, and structural water in beryl and emerald.

    PubMed

    de Donato, Philippe; Cheilletz, Alain; Barres, Odile; Yvon, Jacques

    2004-05-01

    An infrared (IR) study of natural deuteration is conducted on minerals containing hydroxyl groups (talc and kaolinite) and channel-water-bearing minerals (beryl and emerald). In talc, the OD valence vibration is located at 2710 cm(-1), corresponding to OD groups surrounded by 3 Mg atoms. In kaolinite, the OD valence vibrations are located at 2671 cm(-1) (inner OD group), 2712, 2706, and 2700 cm(-1) (three inner-surface OD groups). In beryl and emerald, natural deuteration of channel water is observed for the first time by infrared microspectroscopy. In beryl from Minas Gerais (Brazil), the OD profiles are characterized by four bands at 2735, 2686, 2672, and 2641 cm(-1). In emeralds from Colombia and Brazil, the OD profiles are characterized by five or four bands, respectively, at 2816, 2737, 2685, 2673, and 2641 cm(-1) (Colombia) and 2730, 2684, 2672, and 2640 cm(-1) (Brazil). The band at 2816 cm(-1) can be assigned to -OD or OD(-), and bands at 2686-2684, 2673-2672, and 2641-2640 cm(-1) can be assigned to type-I and type-II HOD molecules. The band at 2737-2730 cm(-1) is partially disturbed by combination bands of the mineral. Such OD profiles are different from those obtained by artificial deuteration at higher OD dilution. PMID:15165327

  5. Infrared spectroscopy of OD vibrators in minerals at natural dilution: hydroxyl groups in talc and kaolinite, and structural water in beryl and emerald.

    PubMed

    de Donato, Philippe; Cheilletz, Alain; Barres, Odile; Yvon, Jacques

    2004-05-01

    An infrared (IR) study of natural deuteration is conducted on minerals containing hydroxyl groups (talc and kaolinite) and channel-water-bearing minerals (beryl and emerald). In talc, the OD valence vibration is located at 2710 cm(-1), corresponding to OD groups surrounded by 3 Mg atoms. In kaolinite, the OD valence vibrations are located at 2671 cm(-1) (inner OD group), 2712, 2706, and 2700 cm(-1) (three inner-surface OD groups). In beryl and emerald, natural deuteration of channel water is observed for the first time by infrared microspectroscopy. In beryl from Minas Gerais (Brazil), the OD profiles are characterized by four bands at 2735, 2686, 2672, and 2641 cm(-1). In emeralds from Colombia and Brazil, the OD profiles are characterized by five or four bands, respectively, at 2816, 2737, 2685, 2673, and 2641 cm(-1) (Colombia) and 2730, 2684, 2672, and 2640 cm(-1) (Brazil). The band at 2816 cm(-1) can be assigned to -OD or OD(-), and bands at 2686-2684, 2673-2672, and 2641-2640 cm(-1) can be assigned to type-I and type-II HOD molecules. The band at 2737-2730 cm(-1) is partially disturbed by combination bands of the mineral. Such OD profiles are different from those obtained by artificial deuteration at higher OD dilution.

  6. Analytical solutions for one-, two-, and three-dimensional solute transport in ground-water systems with uniform flow

    USGS Publications Warehouse

    Wexler, Eliezer J.

    1992-01-01

    Analytical solutions to the advective-dispersive solute-transport equation are useful in predicting the fate of solutes in ground water. Analytical solutions compiled from available literature or derived by the author are presented for a variety of boundary condition types and solute-source configurations in one-, two-, and three-dimensional systems having uniform ground-water flow. A set of user-oriented computer programs was created to evaluate these solutions and to display the results in tabular and computer-graphics format. These programs incorporate many features that enhance their accuracy, ease of use, and versatility. Documentation for the programs describes their operation and required input data, and presents the results of sample problems. Derivations of selected solutions, source codes for the computer programs, and samples of program input and output also are included.

  7. Assessment of optimum dilution ratio for biohydrogen production by anaerobic co-digestion of press mud with sewage and water.

    PubMed

    Radjaram, B; Saravanane, R

    2011-02-01

    Anaerobic co-digestion of press mud with water or sewage at ratios of 1:7.5, 1:10 and 1:12.5 were performed in continuously fed UASB reactors for hydrogen production. At a constant hydraulic retention time of 30 h, the specific hydrogen production rate was 187 mL/g volatile solids (VS) reduced during maximum biohydrogen production of 7960 mL/day at a 1:10 ratio of press mud to sewage. Chemical oxygen demand (COD) and VS reductions of 61% and 59% were noted on peak biohydrogen yield. A pH range of 5-6 was suitable at ambient temperature for entire process; a lower pH was inhibitory. Co-digestion of acidic press mud with sewage controlled pH for fermentation. Hence press mud can be exploited for biohydrogen production.

  8. Deep subsurface drip irrigation using coal-bed sodic water: Part I. Water and solute movement

    SciTech Connect

    Bern, Carleton R; Breit, George N; Healy, Richard W; Zupancic, John W; Hammack, Richard

    2013-02-01

    Water co-produced with coal-bed methane (CBM) in the semi-arid Powder River Basin of Wyoming and Montana commonly has relatively low salinity and high sodium adsorption ratios that can degrade soil permeability where used for irrigation. Nevertheless, a desire to derive beneficial use from the water and a need to dispose of large volumes of it have motivated the design of a deep subsurface drip irrigation (SDI) system capable of utilizing that water. Drip tubing is buried 92 cm deep and irrigates at a relatively constant rate year-round, while evapotranspiration by the alfalfa and grass crops grown is seasonal. We use field data from two sites and computer simulations of unsaturated flow to understand water and solute movements in the SDI fields. Combined irrigation and precipitation exceed potential evapotranspiration by 300–480 mm annually. Initially, excess water contributes to increased storage in the unsaturated zone, and then drainage causes cyclical rises in the water table beneath the fields. Native chloride and nitrate below 200 cm depth are leached by the drainage. Some CBM water moves upward from the drip tubing, drawn by drier conditions above. Chloride from CBM water accumulates there as root uptake removes the water. Year over year accumulations indicated by computer simulations illustrate that infiltration of precipitation water from the surface only partially leaches such accumulations away. Field data show that 7% and 27% of added chloride has accumulated above the drip tubing in an alfalfa and grass field, respectively, following 6 years of irrigation. Maximum chloride concentrations in the alfalfa field are around 45 cm depth but reach the surface in parts of the grass field, illustrating differences driven by crop physiology. Deep SDI offers a means of utilizing marginal quality irrigation waters and managing the accumulation of their associated solutes in the crop rooting zone.

  9. Deep subsurface drip irrigation using coal-bed sodic water: part I. water and solute movement

    USGS Publications Warehouse

    Bern, Carleton R.; Breit, George N.; Healy, Richard W.; Zupancic, John W.; Hammack, Richard

    2013-01-01

    Water co-produced with coal-bed methane (CBM) in the semi-arid Powder River Basin of Wyoming and Montana commonly has relatively low salinity and high sodium adsorption ratios that can degrade soil permeability where used for irrigation. Nevertheless, a desire to derive beneficial use from the water and a need to dispose of large volumes of it have motivated the design of a deep subsurface drip irrigation (SDI) system capable of utilizing that water. Drip tubing is buried 92 cm deep and irrigates at a relatively constant rate year-round, while evapotranspiration by the alfalfa and grass crops grown is seasonal. We use field data from two sites and computer simulations of unsaturated flow to understand water and solute movements in the SDI fields. Combined irrigation and precipitation exceed potential evapotranspiration by 300-480 mm annually. Initially, excess water contributes to increased storage in the unsaturated zone, and then drainage causes cyclical rises in the water table beneath the fields. Native chloride and nitrate below 200 cm depth are leached by the drainage. Some CBM water moves upward from the drip tubing, drawn by drier conditions above. Chloride from CBM water accumulates there as root uptake removes the water. Year over year accumulations indicated by computer simulations illustrate that infiltration of precipitation water from the surface only partially leaches such accumulations away. Field data show that 7% and 27% of added chloride has accumulated above the drip tubing in an alfalfa and grass field, respectively, following 6 years of irrigation. Maximum chloride concentrations in the alfalfa field are around 45 cm depth but reach the surface in parts of the grass field, illustrating differences driven by crop physiology. Deep SDI offers a means of utilizing marginal quality irrigation waters and managing the accumulation of their associated solutes in the crop rooting zone.

  10. Microfluidic serial dilution ladder.

    PubMed

    Ahrar, Siavash; Hwang, Michelle; Duncan, Philip N; Hui, Elliot E

    2014-01-01

    Serial dilution is a fundamental procedure that is common to a large number of laboratory protocols. Automation of serial dilution is thus a valuable component for lab-on-a-chip systems. While a handful of different microfluidic strategies for serial dilution have been reported, approaches based on continuous flow mixing inherently consume larger amounts of sample volume and chip real estate. We employ valve-driven circulatory mixing to address these issues and also introduce a novel device structure to store each stage of the dilution process. The dilution strategy is based on sequentially mixing the rungs of a ladder structure. We demonstrate a 7-stage series of 1 : 1 dilutions with R(2) equal to 0.995 in an active device area of 1 cm(2).

  11. Mixing zone and drinking water intake dilution factor and wastewater generation distributions to enable probabilistic assessment of down-the-drain consumer product chemicals in the U.S.

    PubMed

    Kapo, Katherine E; McDonough, Kathleen; Federle, Thomas; Dyer, Scott; Vamshi, Raghu

    2015-06-15

    Environmental exposure and associated ecological risk related to down-the-drain chemicals discharged by municipal wastewater treatment plants (WWTPs) are strongly influenced by in-stream dilution of receiving waters which varies by geography, flow conditions and upstream wastewater inputs. The iSTREEM® model (American Cleaning Institute, Washington D.C.) was utilized to determine probabilistic distributions for no decay and decay-based dilution factors in mean annual and low (7Q10) flow conditions. The dilution factors derived in this study are "combined" dilution factors which account for both hydrologic dilution and cumulative upstream effluent contributions that will differ depending on the rate of in-stream decay due to biodegradation, volatilization, sorption, etc. for the chemical being evaluated. The median dilution factors estimated in this study (based on various in-stream decay rates from zero decay to a 1h half-life) for WWTP mixing zones dominated by domestic wastewater flow ranged from 132 to 609 at mean flow and 5 to 25 at low flow, while median dilution factors at drinking water intakes (mean flow) ranged from 146 to 2×10(7) depending on the in-stream decay rate. WWTPs within the iSTREEM® model were used to generate a distribution of per capita wastewater generated in the U.S. The dilution factor and per capita wastewater generation distributions developed by this work can be used to conduct probabilistic exposure assessments for down-the-drain chemicals in influent wastewater, wastewater treatment plant mixing zones and at drinking water intakes in the conterminous U.S. In addition, evaluation of types and abundance of U.S. wastewater treatment processes provided insight into treatment trends and the flow volume treated by each type of process. Moreover, removal efficiencies of chemicals can differ by treatment type. Hence, the availability of distributions for per capita wastewater production, treatment type, and dilution factors at a national

  12. Raman spectroscopic study of sodium chloride water solutions

    NASA Astrophysics Data System (ADS)

    Furić, K.; Ciglenečki, I.; Ćosović, B.

    2000-09-01

    The Raman spectra of NaCl water solutions have been studied in the concentration range between 0 and 3.3 M using a difference technique. The temperature dependence of the spectral profiles observed for the O-H stretching in the high frequency region (between 2500 and 4000 cm -1) was also investigated in the narrow interval around a room temperature. Although the considered bandshape is not of a simple kind, the measured Id/ I0 ratio plotted versus NaCl concentration and temperature fits a straight line in both diagrams very satisfactorily. The linear dependence of Id/ I0 versus NaCl molarity was checked in the study of natural seawater samples for which discrepancies were found. These deviations were attributed to other organic and inorganic dissolved components in the seawater.

  13. An Integrated Water Treatment Technology Solution for Sustainable Water Resource Management in the Marcellus Shale

    SciTech Connect

    Matthew Bruff; Ned Godshall; Karen Evans

    2011-04-30

    This Final Scientific/ Technical Report submitted with respect to Project DE-FE0000833 titled 'An Integrated Water Treatment Technology Solution for Sustainable Water Resource Management in the Marcellus Shale' in support of final reporting requirements. This final report contains a compilation of previous reports with the most current data in order to produce one final complete document. The goal of this research was to provide an integrated approach aimed at addressing the increasing water resource challenges between natural gas production and other water stakeholders in shale gas basins. The objective was to demonstrate that the AltelaRain{reg_sign} technology could be successfully deployed in the Marcellus Shale Basin to treat frac flow-back water. That objective has been successfully met.

  14. The mathematics of dilution.

    PubMed

    Chatterjee, Barun Kumar

    2014-04-01

    The major objection to homeopathic medicine is that the doses of medicine prescribed in some cases are too dilute for any active ingredient to be present. The medicines would hence be rendered inactive, necessitating novel explanations for the action. A further examination of dilution in the light of the Langmuir equation shows that homeopathic medicines may not be as dilute as a simplistic application of Avogadro's Principle suggests, due to surface effects.

  15. Roles of surface water areas for water and solute cycle in Hanoi city, Viet Nam

    NASA Astrophysics Data System (ADS)

    Hayashi, Takeshi; Kuroda, Keisuke; Do Thuan, An; Tran Thi Viet, Nga; Takizawa, Satoshi

    2013-04-01

    Hanoi city, the capital of Viet Nam, has developed beside the Red river. Recent rapid urbanization of this city has reduced a large number of natural water areas such as lakes, ponds and canals not only in the central area but the suburban area. Contrary, the urbanization has increased artificial water areas such as pond for fish cultivation and landscaping. On the other hand, the urbanization has induced the inflow of waste water from households and various kinds of factories to these water areas because of delay of sewerage system development. Inflow of the waste water has induced eutrophication and pollution of these water areas. Also, there is a possibility of groundwater pollution by infiltration of polluted surface water. However, the role of these water areas for water cycle and solute transport is not clarified. Therefore, this study focuses on the interaction between surface water areas and groundwater in Hanoi city to evaluate appropriate land development and groundwater resource management. We are carrying out three approaches: a) understanding of geochemical characteristics of surface water and groundwater, b) monitoring of water levels of pond and groundwater, c) sampling of soil and pond sediment. Correlation between d18O and dD of precipitation (after GNIP), the Red River (after GNIR) and the water samples of this study showed that the groundwater is composed of precipitation, the Red River and surface water that has evaporation process. Contribution of the surface water with evaporation process was widely found in the study area. As for groundwater monitoring, the Holocene aquifers at two sites were in unconfined condition in dry season and the groundwater levels in the aquifer continued to increase through rainy season. The results of isotopic analysis and groundwater level monitoring showed that the surface water areas are one of the major groundwater sources. On the other hand, concentrations of dissolved Arsenic (filtered by 0.45um) in the pore

  16. The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions.

    PubMed

    Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

    2016-01-01

    It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions. PMID:27225427

  17. The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions

    PubMed Central

    Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

    2016-01-01

    It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions. PMID:27225427

  18. The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions

    NASA Astrophysics Data System (ADS)

    Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

    2016-05-01

    It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions.

  19. AST/R BASED WATER REUSE AS A PART OF THE TOTAL WATER SOLUTION FOR WATER-STRESSED REGIONS: AN OVERVIEW OF ENGINEERING PRACTICE AND REGULATORY PROSPECTIVE

    EPA Science Inventory

    Water supply and demand are increasingly unbalanced in many parts of the world. To address the imbalance, the total water solution methodology simultaneously considers regulatory, engineering, environmental and economic factors to optimize risk management solutions for an entire ...

  20. AST/R–BASED WATER REUSE AS A PART OF THE TOTAL WATER SOLUTION FOR WATER-STRESSED REGIONS: AN OVERVIEW OF ENGINEERING PRACTICE AND REGULATORY PROSPECTIVE

    EPA Science Inventory

    Water supply and demand are increasingly unbalanced in many parts of the world. To address the imbalance, the total water solution methodology simultaneously considers regulatory, engineering, environmental and economic factors to optimize risk management solutions for an entire...

  1. [Preventive trial of preheating administration of oxaliplatin-diluted solution in combination with a hot compress for oxaliplatin-induced venous pain].

    PubMed

    Miyajima, Risa; Kawazoe, Hitoshi; Tsuneoka, Kikue; Fujiwara, Mitsuko; Kojima, Yoh; Yakushijin, Yoshihiro

    2013-04-01

    Venous pain induced by oxaliplatin (L-OHP) is a clinical problem in relation to adherence in the CapeOX regimen. We investigated the preventive effect of nursing care preheating administration of L-OHP a hot compress for colorectal cancer patients who received L-OHP via the peripheral venous route between January 2010 and January 2011. L-OHP was diluted in 500 mL of 5% glucose and administered by 2 hours. We evaluated a total of 64 courses among fifteen patients. The presence of any symptoms, any pain with or without touch, and some symptoms of numbness at the L-OHP-administered arm were defined as phlebitis, venous pain, and acute peripheral neuropathy, respectively. The prevalence of phlebitis, venous pain, and acute peripheral neuropathy in the nursing care group was 56.5%, 32.6%, and 25.8%, respectively, which was not significantly less in comparison with the control group (72.2%, 38.9%, and 54.5%, respectively). These results suggest that both types of nursing care, preheating administration and a hot compress, may be effective for the relief of acute peripheral neuropathy induced by L-OHP.

  2. Approximate solutions for Forchheimer flow during water injection and water production in an unconfined aquifer

    NASA Astrophysics Data System (ADS)

    Mathias, Simon A.; Moutsopoulos, Konstantinos N.

    2016-07-01

    Understanding the hydraulics around injection and production wells in unconfined aquifers associated with rainwater and reclaimed water aquifer storage schemes is an issue of increasing importance. Much work has been done previously to understand the mathematics associated with Darcy's law in this context. However, groundwater flow velocities around injection and production wells are likely to be sufficiently large such as to induce significant non-Darcy effects. This article presents a mathematical analysis to look at Forchheimer's equation in the context of water injection and water production in unconfined aquifers. Three different approximate solutions are derived using quasi-steady-state assumptions and the method of matched asymptotic expansion. The resulting approximate solutions are shown to be accurate for a wide range of practical scenarios by comparison with a finite difference solution to the full problem of concern. The approximate solutions have led to an improved understanding of the flow dynamics. They can also be used as verification tools for future numerical models in this context.

  3. Excess chemical potential of small solutes across water--membrane and water--hexane interfaces

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Wilson, M. A.

    1996-01-01

    The excess chemical potentials of five small, structurally related solutes, CH4, CH3F, CH2F2, CHF3, and CF4, across the water-glycerol 1-monooleate bilayer and water-hexane interfaces were calculated at 300, 310, and 340 K using the particle insertion method. The excess chemical potentials of nonpolar molecules (CH4 and CF4) decrease monotonically or nearly monotonically from water to a nonpolar phase. In contrast, for molecules that possess permanent dipole moments (CH3F, CH2F, and CHF3), the excess chemical potentials exhibit an interfacial minimum that arises from superposition of two monotonically and oppositely changing contributions: electrostatic and nonelectrostatic. The nonelectrostatic term, dominated by the reversible work of creating a cavity that accommodates the solute, decreases, whereas the electrostatic term increases across the interface from water to the membrane interior. In water, the dependence of this term on the dipole moment is accurately described by second order perturbation theory. To achieve the same accuracy at the interface, third order terms must also be included. In the interfacial region, the molecular structure of the solvent influences both the excess chemical potential and solute orientations. The excess chemical potential across the interface increases with temperature, but this effect is rather small. Our analysis indicates that a broad range of small, moderately polar molecules should be surface active at the water-membrane and water-oil interfaces. The biological and medical significance of this result, especially in relation to the mechanism of anesthetic action, is discussed.

  4. Community of Practice Applications from WaterNet: The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Matthews, D.; Brilly, M.; Gregoric, G.; Polajnar, J.; Houser, P.; Rodell, M.; Lehning, M.

    2009-04-01

    WaterNet is a new international network of researchers, stakeholders, and end-users of remote sensing tools that will benefit the water resources management community. It addresses a means for enhancing the social and economic developments of nations by increased use of practical research products from the terrestrial water cycle for making informed decisions. This paper provides a summary of the Water Cycle Community of Practice (CoP) plans and examples of Land Surface Model (LSM) applications for extreme events - floods, droughts, and heavy snowstorms in Europe. It discusses the concept of NASA's solutions networks focusing on the WaterNet. It invites EGU teams to join our WaterNet network. The NASA Water cycle Solutions Network's goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. Our team is developing WaterNet by engaging relevant NASA water cycle research and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect NASA Water cycle research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing that the European Commission and European Space Agency have also developed many related research products (EWRs), we seek to learn about these and network with the EU teams to include their information in the WaterNet actionable data base. Recognizing the many existing highly valuable water-related science and application networks in the US and EU, we focus the balance of our efforts on enabling their interoperability - facilitating access and communications among decision-makers and scientists. We present results of our initial focus on identification, collection, and analysis of the two end points, these being the NWRs and EWRs and water related DSTs. We

  5. Dynamics of water solutions of natural polysaccharides by fast field cycling nmr relaxometry

    NASA Astrophysics Data System (ADS)

    Prusova, Alena; Conte, Pellegrino; Kucerik, Jiri; de Pasquale, Claudio; Alonzo, Giuseppe

    2010-05-01

    Cryobiology studies the effect of low temperatures on living systems such as microorganisms and plants. In particular, plants growing in cold or frozen environments can survive such extreme conditions due to the cold hardening process. Hardening is a three step process during which, first, translocation of polysaccharides to the plant roots affects water structure in the cell-soil surface. For this reason, increase of cell-membrane permeability and resistance to temperatures from -5°C to -10°C is achieved. In a second step, chemical alteration of cell membrane arises and resistance to temperatures up to -20°C is obtained. The last hardening step consists in the vitrification of the plant tissues which allow plants to survive at temperatures as low as -50°C. Since polysaccharides play a very important role in the initial part of the cold hardening process, it is of paramount importance to study the effect of such natural biopolymers on water structure. Here, we present preliminary data obtained by fast field cycling NMR relaxometry on the effect of hyaluronan (an anionic, non-sulfated glycosaminoglycan) on water structure at different concentrations of the polysaccharide. Although hyaluronan is a polysaccharide found exceptionally in animal, human or bacterial bodies, in the present work it was used as a model "pilot" compound. In fact, it has an unique ability to hold water and it contains both polysaccharide and protein-like acetamido functionalities. For this reason, hyaluronan promotes the future research on other plant biopolymers such as, for instance, starch and other very specific proteins. Results revealed that different water-structure systems surround the molecule of hyaluronan in diluted and semidiluted systems. Namely, at the lowest hyaluronan concentration, three hydration shells can be recognized. The first hydration shell is made by bound water (BW) which is strongly fixed to the hyaluronan surface mainly through electrostatic interactions. A

  6. Computer model of two-dimensional solute transport and dispersion in ground water

    USGS Publications Warehouse

    Konikow, Leonard F.; Bredehoeft, J.D.

    1978-01-01

    This report presents a model that simulates solute transport in flowing ground water. The model is both general and flexible in that it can be applied to a wide range of problem types. It is applicable to one- or two-dimensional problems involving steady-state or transient flow. The model computes changes in concentration over time caused by the processes of convective transport, hydrodynamic dispersion, and mixing (or dilution) from fluid sources. The model assumes that the solute is non-reactive and that gradients of fluid density, viscosity, and temperature do not affect the velocity distribution. However, the aquifer may be heterogeneous and (or) anisotropic. The model couples the ground-water flow equation with the solute-transport equation. The digital computer program uses an alternating-direction implicit procedure to solve a finite-difference approximation to the ground-water flow equation, and it uses the method of characteristics to solve the solute-transport equation. The latter uses a particle- tracking procedure to represent convective transport and a two-step explicit procedure to solve a finite-difference equation that describes the effects of hydrodynamic dispersion, fluid sources and sinks, and divergence of velocity. This explicit procedure has several stability criteria, but the consequent time-step limitations are automatically determined by the program. The report includes a listing of the computer program, which is written in FORTRAN IV and contains about 2,000 lines. The model is based on a rectangular, block-centered, finite difference grid. It allows the specification of any number of injection or withdrawal wells and of spatially varying diffuse recharge or discharge, saturated thickness, transmissivity, boundary conditions, and initial heads and concentrations. The program also permits the designation of up to five nodes as observation points, for which a summary table of head and concentration versus time is printed at the end of the

  7. Stress in dilute suspensions

    NASA Technical Reports Server (NTRS)

    Passman, Stephen L.

    1989-01-01

    Generally, two types of theory are used to describe the field equations for suspensions. The so-called postulated equations are based on the kinetic theory of mixtures, which logically should give reasonable equations for solutions. The basis for the use of such theory for suspensions is tenuous, though it at least gives a logical path for mathematical arguments. It has the disadvantage that it leads to a system of equations which is underdetermined, in a sense that can be made precise. On the other hand, the so-called averaging theory starts with a determined system, but the very process of averaging renders the resulting system underdetermined. A third type of theory is proposed in which the kinetic theory of gases is used to motivate continuum equations for the suspended particles. This entails an interpretation of the stress in the particles that is different from the usual one. Classical theory is used to describe the motion of the suspending medium. The result is a determined system for a dilute suspension. Extension of the theory to more concentrated systems is discussed.

  8. Ultra-trace level speciated isotope dilution measurement of Cr(VI) using ion chromatography tandem mass spectrometry in environmental waters.

    PubMed

    Mädler, Stefanie; Todd, Aaron; Skip Kingston, H M; Pamuku, Matt; Sun, Fengrong; Tat, Cindy; Tooley, Robert J; Switzer, Teresa A; Furdui, Vasile I

    2016-08-15

    The reliable analysis of highly toxic hexavalent chromium, Cr(VI), at ultra-trace levels remains challenging, given its easy conversion to non-toxic trivalent chromium. This work demonstrates a novel analytical method to quantify Cr(VI) at low ngL(-1) concentration levels in environmental water samples by using speciated isotope dilution (SID) analysis and double-spiking with Cr(III) and Cr(VI) enriched for different isotopes. Ion chromatography tandem mass spectrometry (IC-MS/MS) was used for the analysis of Cr(VI) as HCrO4(-) → CrO3(-). Whereas the classical linear multipoint calibration (MPC) curve approach obtained a method detection limit (MDL) of 7ngL(-1) Cr(VI), the modified SID-MS method adapted from U. S. EPA 6800 allowed for the quantification of Cr(VI) with an MDL of 2ngL(-1) and provided results corrected for Cr(VI) loss occurred after sample collection. The adapted SID-MS approach proved to yield more accurate and precise results than the MPC method, allowed for compensation of Cr(VI) reduction during sample transportation and storage while eliminating the need for frequent external calibration. The developed method is a complementary tool to routinely used inductively-coupled plasma (ICP) MS and circumvents typically experienced interferences.

  9. Insights into the effect of dilute acid, hot water and alkaline pretreatment on cellulose accessible surface area and overall porosity of Populus

    SciTech Connect

    Meng, Xianzhi; Wells, Tyrone; Sun, Qining; Huang, Fang; Ragauskas, Arthur J.

    2015-06-19

    Pretreatment is known to render biomass more reactive to cellulase by altering the chemical compositions as well as physical structures of biomass. Simons stain technique along with mercury porosimetry were applied on the acid, neutral, and alkaline pretreated materials to measure the accessible surface area of cellulose and pore size distribution of Populus. Results indicated that acid pretreatment is much more effective than water and alkaline pretreatment in terms of cellulose accessibility increase. Further investigation suggests that lignin does not dictate cellulose accessibility to the extent that hemicellulose does, but it does restrict xylan accessibility which in turn controls the access of cellulase to cellulose. The most interesting finding is that severe acid pretreatment significantly decreases the average pore size, i.e., 90% average size decrease could be observed after 60 min dilute acid pretreatment at 160 °C; moreover, the nano-pore space formed between coated microfibrils is increased after pretreatment, especially for the acid pretreatment, suggesting this particular type of biomass porosity is probably the most fundamental barrier to effective enzymatic hydrolysis.

  10. Insights into the effect of dilute acid, hot water and alkaline pretreatment on cellulose accessible surface area and overall porosity of Populus

    DOE PAGESBeta

    Meng, Xianzhi; Wells, Tyrone; Sun, Qining; Huang, Fang; Ragauskas, Arthur J.

    2015-06-19

    Pretreatment is known to render biomass more reactive to cellulase by altering the chemical compositions as well as physical structures of biomass. Simons stain technique along with mercury porosimetry were applied on the acid, neutral, and alkaline pretreated materials to measure the accessible surface area of cellulose and pore size distribution of Populus. Results indicated that acid pretreatment is much more effective than water and alkaline pretreatment in terms of cellulose accessibility increase. Further investigation suggests that lignin does not dictate cellulose accessibility to the extent that hemicellulose does, but it does restrict xylan accessibility which in turn controls themore » access of cellulase to cellulose. The most interesting finding is that severe acid pretreatment significantly decreases the average pore size, i.e., 90% average size decrease could be observed after 60 min dilute acid pretreatment at 160 °C; moreover, the nano-pore space formed between coated microfibrils is increased after pretreatment, especially for the acid pretreatment, suggesting this particular type of biomass porosity is probably the most fundamental barrier to effective enzymatic hydrolysis.« less

  11. Conversion of organic solid waste to hydrogen and methane by two-stage fermentation system with reuse of methane fermenter effluent as diluting water in hydrogen fermentation.

    PubMed

    Jung, Kyung-Won; Moon, Chungman; Cho, Si-Kyung; Kim, Sang-Hyoun; Shin, Hang-Sik; Kim, Dong-Hoon

    2013-07-01

    In this study, a two-stage system converting organic solid waste (food waste+sewage sludge) to H2 and CH4 was operated. In the first stage of dark fermentative hydrogen production (DFHP), a recently proposed method that does not require external inoculum, was applied. In the second stage, anaerobic sequencing batch reactor (ASBR) and an up-flow anaerobic sludge blanket reactor (UASBr) were followed to treat H2 fermenter effluent. (H2+CH4-ASBR) system showed better performance in terms of total biogas conversion (78.6%), while higher biogas production rate (2.03 L H2/Lsystem/d, 1.96 L CH4/Lsystem/d) was achieved in (H2+CH4-UASBr) system. To reduce the alkali addition requirement in DFHP process, CH4 fermenter effluent was tested as a diluting water. Both the ASBR and UASBr effluent was effective to keep the pH above 6 without CH4 production. In case of using ASBR effluent, H2 production dropped by 15%, but alkali addition requirement was reduced by 50%.

  12. Development and validation of a liquid chromatography isotope dilution mass spectrometry method for the reliable quantification of alkylphenols in environmental water samples by isotope pattern deconvolution.

    PubMed

    Fabregat-Cabello, Neus; Sancho, Juan V; Vidal, Andreu; González, Florenci V; Roig-Navarro, Antoni Francesc

    2014-02-01

    We present here a new measurement method for the rapid extraction and accurate quantification of technical nonylphenol (NP) and 4-t-octylphenol (OP) in complex matrix water samples by UHPLC-ESI-MS/MS. The extraction of both compounds is achieved in 30min by means of hollow fiber liquid phase microextraction (HF-LPME) using 1-octanol as acceptor phase, which provides an enrichment (preconcentration) factor of 800. On the other hand we have developed a quantification method based on isotope dilution mass spectrometry (IDMS) and singly (13)C1-labeled compounds. To this end the minimal labeled (13)C1-4-(3,6-dimethyl-3-heptyl)-phenol and (13)C1-t-octylphenol isomers were synthesized, which coelute with the natural compounds and allows the compensation of the matrix effect. The quantification was carried out by using isotope pattern deconvolution (IPD), which permits to obtain the concentration of both compounds without the need to build any calibration graph, reducing the total analysis time. The combination of both extraction and determination techniques have allowed to validate for the first time a HF-LPME methodology at the required levels by legislation achieving limits of quantification of 0.1ngmL(-1) and recoveries within 97-109%. Due to the low cost of HF-LPME and total time consumption, this methodology is ready for implementation in routine analytical laboratories. PMID:24423386

  13. Community of Practice Applications from WaterNet: The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Matthews, D.; Brilly, M.; Gregoric, G.; Polajnar, J.; Houser, P.; Rodell, M.; Lehning, M.

    2009-04-01

    WaterNet is a new international network of researchers, stakeholders, and end-users of remote sensing tools that will benefit the water resources management community. It addresses a means for enhancing the social and economic developments of nations by increased use of practical research products from the terrestrial water cycle for making informed decisions. This paper provides a summary of the Water Cycle Community of Practice (CoP) plans and examples of Land Surface Model (LSM) applications for extreme events - floods, droughts, and heavy snowstorms in Europe. It discusses the concept of NASA's solutions networks focusing on the WaterNet. It invites EGU teams to join our WaterNet network. The NASA Water cycle Solutions Network's goal is to improve and optimize the sustained ability of water cycle researchers, stakeholders, organizations and networks to interact, identify, harness, and extend NASA research results to augment decision support tools and meet national needs. Our team is developing WaterNet by engaging relevant NASA water cycle research and community-of-practice organizations, to develop what we term an "actionable database" that can be used to communicate and connect NASA Water cycle research Results (NWRs) towards the improvement of water-related Decision Support Tools (DSTs). Recognizing that the European Commission and European Space Agency have also developed many related research products (EWRs), we seek to learn about these and network with the EU teams to include their information in the WaterNet actionable data base. Recognizing the many existing highly valuable water-related science and application networks in the US and EU, we focus the balance of our efforts on enabling their interoperability - facilitating access and communications among decision-makers and scientists. We present results of our initial focus on identification, collection, and analysis of the two end points, these being the NWRs and EWRs and water related DSTs. We

  14. Validation and uncertainties evaluation of an isotope dilution-SPE-LC-MS/MS for the quantification of drug residues in surface waters.

    PubMed

    Brieudes, V; Lardy-Fontan, S; Lalere, B; Vaslin-Reimann, S; Budzinski, H

    2016-01-01

    The present work describes the development and validation of a reference method conducted at the French National Institute of Metrology (LNE) for the quantitative determination of psychoactive compounds in the dissolved fraction of surface waters. More specifically an isotope dilution-SPE-LC-MS/MS based method has been implemented for the characterization of a broad range of analytes belonging to different classes of psychotropic drugs such as benzodiazepines, antidepressants, stimulants, opiates and opioids, anticonvulsants, anti-dementia drugs, analgesics as well as the anti-inflammatory drug diclofenac in the low ng L(-1) range of concentration. Full validation of the method was performed following procedures described by the French standard NF T90-210. Limits of quantification between 0.14 and 3.54 ng L(-1) were obtained. Method recoveries from 71 to 123% were observed with standard deviation below 10% in intermediate precision conditions. Accuracy was determined for every compound: measurement errors were between -4 and +1% and standard deviations in intermediate precision conditions were included within a 1-9% interval. Finally, measurement uncertainties were evaluated following the Guide to the expression of uncertainty in measurement (GUM). Expanded uncertainties (k=2) ranged from 2% for carbamazepine, EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) and venlafaxine to 17% for diazepam. The validated method was implemented to Seine river surface waters demonstrating its fitness for purpose. All compounds were detected and 22 out of 25 analytes were quantified. More specifically, measured concentration ranged from 0.39 ng L(-1) for MDMA (3,4-methylene-dioxy-N-methylamphetamine) to 182 ng L(-1) for gabapentine.

  15. Validation and uncertainties evaluation of an isotope dilution-SPE-LC-MS/MS for the quantification of drug residues in surface waters.

    PubMed

    Brieudes, V; Lardy-Fontan, S; Lalere, B; Vaslin-Reimann, S; Budzinski, H

    2016-01-01

    The present work describes the development and validation of a reference method conducted at the French National Institute of Metrology (LNE) for the quantitative determination of psychoactive compounds in the dissolved fraction of surface waters. More specifically an isotope dilution-SPE-LC-MS/MS based method has been implemented for the characterization of a broad range of analytes belonging to different classes of psychotropic drugs such as benzodiazepines, antidepressants, stimulants, opiates and opioids, anticonvulsants, anti-dementia drugs, analgesics as well as the anti-inflammatory drug diclofenac in the low ng L(-1) range of concentration. Full validation of the method was performed following procedures described by the French standard NF T90-210. Limits of quantification between 0.14 and 3.54 ng L(-1) were obtained. Method recoveries from 71 to 123% were observed with standard deviation below 10% in intermediate precision conditions. Accuracy was determined for every compound: measurement errors were between -4 and +1% and standard deviations in intermediate precision conditions were included within a 1-9% interval. Finally, measurement uncertainties were evaluated following the Guide to the expression of uncertainty in measurement (GUM). Expanded uncertainties (k=2) ranged from 2% for carbamazepine, EDDP (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine) and venlafaxine to 17% for diazepam. The validated method was implemented to Seine river surface waters demonstrating its fitness for purpose. All compounds were detected and 22 out of 25 analytes were quantified. More specifically, measured concentration ranged from 0.39 ng L(-1) for MDMA (3,4-methylene-dioxy-N-methylamphetamine) to 182 ng L(-1) for gabapentine. PMID:26695245

  16. Infiltration of water and ethanol solutions in water repellent post wildfire soils

    NASA Astrophysics Data System (ADS)

    Beatty, Sarah M.; Smith, James E.

    2014-06-01

    Dynamic soil water repellency is a pending challenge in water repellency research. The dynamic change or temporal dependence of repellency is commonly expressed as the persistence of repellency. Persistence, or dynamic changes in contact angle, are however, difficult to directly measure and incorporate into mechanistic conceptual and numerical models. To provide insight into the mechanistic nature of infiltration in variably repellent porous media over larger spatial and temporal scales than afforded by commonly applied characterization approaches (i.e. drop tests), this study reports upon observations made during in situ 3D tension infiltration experiments conducted at a post-wildfire site. Tension infiltration tests have proven to be uniquely sensitive to changes in repellency over time. Tension infiltration experiments using mini-disk infiltrometers were conducted. Drop tests provided initial measures of repellency. Tension infiltration experiments were used to generate insights on longer term infiltration behaviours using water, ethanol, and aqueous-ethanol solutions. Molarity of Ethanol Drop (MED) - derived aqueous ethanol solutions (of 5%, 25% and 50% ethanol concentration) were used as intermediate infiltration fluids to generate greater insight into the transitional behaviours between repellent and apparently wettable infiltration. Early time infiltration rates are not reliable indicators of longer term infiltration rates. However, relating the two measures was informative in characterising repellency across materials and at different sites, while preserving temporal differences in fluid behaviours. Comparison of the late-time infiltration rates of aqueous solutions of varying ethanol concentrations proved a useful indicator of repellency and fractional wettability effects.

  17. Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions

    NASA Astrophysics Data System (ADS)

    Wutich, A.; White, A. C.; White, D. D.; Larson, K. L.; Brewis, A.; Roberts, C.

    2014-01-01

    In this study, we examine how development status and water scarcity shape people's perceptions of "hard path" and "soft path" water solutions. Based on ethnographic research conducted in four semi-rural/peri-urban sites (in Bolivia, Fiji, New Zealand, and the US), we use content analysis to conduct statistical and thematic comparisons of interview data. Our results indicate clear differences associated with development status and, to a lesser extent, water scarcity. People in the two less developed sites were more likely to suggest hard path solutions, less likely to suggest soft path solutions, and more likely to see no path to solutions than people in the more developed sites. Thematically, people in the two less developed sites envisioned solutions that involve small-scale water infrastructure and decentralized, community-based solutions, while people in the more developed sites envisioned solutions that involve large-scale infrastructure and centralized, regulatory water solutions. People in the two water-scarce sites were less likely to suggest soft path solutions and more likely to see no path to solutions (but no more likely to suggest hard path solutions) than people in the water-rich sites. Thematically, people in the two water-rich sites seemed to perceive a wider array of unrealized potential soft path solutions than those in the water-scarce sites. On balance, our findings are encouraging in that they indicate that people are receptive to soft path solutions in a range of sites, even those with limited financial or water resources. Our research points to the need for more studies that investigate the social feasibility of soft path water solutions, particularly in sites with significant financial and natural resource constraints.

  18. Hard paths, soft paths or no paths? Cross-cultural perceptions of water solutions

    NASA Astrophysics Data System (ADS)

    Wutich, A.; White, A. C.; Roberts, C. M.; White, D. D.; Larson, K. L.; Brewis, A.

    2013-06-01

    In this study, we examine how development status and water scarcity shape people's perceptions of "hard path" and "soft path" water solutions. Based on ethnographic research conducted in four semi-rural/peri-urban sites (in Bolivia, Fiji, New Zealand, and the US), we use content analysis to conduct statistical and thematic comparisons of interview data. Our results indicate clear differences based on development status and, to a lesser extent, water scarcity. People in less developed sites were more likely to suggest hard path solutions, less likely to suggest soft path solutions, and more likely to see no path to solutions than people in more developed sites. Thematically, people in less developed sites envisioned solutions that involve small-scale water infrastructure and decentralized, community based solutions, while people in more developed sites envisioned solutions that involve large-scale infrastructure and centralized, regulatory water solutions. People in water-scarce sites were less likely to suggest soft path solutions and more likely to see no path to solutions (but no more likely to suggest hard path solutions) than people in water-rich sites. Thematically, people in water-rich sites seemed to perceive a wider array of unrealized potential soft path solutions than those in water-scarce sites. On balance, our findings are encouraging in that they indicate that people are receptive to soft path solutions in a range of sites, even those with limited financial or water resources. Our research points to the need for more studies that investigate the social feasibility of soft path water solutions, particularly in sites with significant financial and natural resource constraints.

  19. Measurements of the Distribution of Solutes between Liquid Water and Steam

    SciTech Connect

    Palmer, D.A.; Simonson, J.M.; Ho, P.C.

    1997-12-31

    Direct measurements of the concentration of solutes in both liquid and steam phases in equilibrium with each other have been made in a static mode utilizing a platinum-lined autoclave to a maximum of 350 deg C. Partitioning constants were derived from these measurements based on existing experimental or estimated values of the stoichiometric mean activity coefficients for the solutes in the liquid phase. Independent measurements of the conductance of some of the solutes in dilute aqueous solutions to 600 deg C and 300MPa were also made. The combined results are discussed in terms of a speciated model and the implications of these results to industrial and natural hydrothermal processes are presented. PARTITIONING CONSTANT, ION-ASSOCIATION, CONDUCTIVITY, SPECIATION, CORROSION.

  20. Surface Electrostatic Potential and Water Orientation in the presence of Sodium Octanoate Dilute Monolayers Studied by Means of Molecular Dynamics Simulations.

    PubMed

    Bernardino, Kalil; de Moura, André F

    2015-10-13

    A series of atomistic molecular dynamics simulations were performed in the present investigation to assess the spontaneous formation of surfactant monolayers of sodium octanoate at the water-vacuum interface. The surfactant surface coverage increased until a saturation threshold was achieved, after which any further surfactant addition led to the formation of micellar aggregates within the solution. The saturated films were not densely packed, as might be expected for short-chained surfactants, and all films regardless of the surface coverage presented surfactant molecules with the same ordering pattern, namely, with the ionic heads toward the aqueous solution and the tails lying nearly parallel to the interface. The major contributions to the electrostatic surface potential came from the charged heads and the counterion distribution, which nearly canceled out each other. The balance between the oppositely charged ions rendered the electrostatic contributions from water meaningful, amounting to ca. 10% of the contributions arising from the ionic species. And even the aliphatic tails, whose atoms bear relatively small partial atomic charges as compared to the polar molecules and molecular fragments, contributed with ca. 20% of the total electrostatic surface potential of the systems under investigation. Although the aliphatic tails were not so orderly arranged as in a compact film, the C-H bonds assumed a preferential orientation, leading to an increased contribution to the electrostatic properties of the interface. The most prominent feature arising from the partitioning of the electrostatic potential into individual contributions was the long-range ordering of the water molecules. This ordering of the water molecules produced a repulsive dipole-dipole interaction between the two interfaces, which increased with the surface coverage. Only for a water layer wider than 10 nm was true bulk behavior observed, and the repulsive dipole-dipole interaction faded away. PMID

  1. The anomaly of oxygen diffusion in aqueous xanthan solutions.

    PubMed

    Ho, C S; Ju, L K; Baddour, R F

    1988-06-20

    A membrane-covered polarographic oxygen electrode was used to measure oxygen diffusion coefficients in aqueous polyelectrolyte solutions of xanthan gum, sodium alginate, and sodium carboxymethylcellulose (CMC). In sodium alginate solutions, dilute xanthan solutions, and solutions containing more than 0.3 wt % CMC, oxygen diffusion coefficients decrease with increasing polymer concentrations. Interestingly, in dilute CMC solutions and concentrate xanthan solutions containing more than 0.5 wt % xanthan gum, oxygen diffusion coefficients increase with increasing polymer concentrations, and values exceeding that in pure water are generally observed.

  2. Predictability of tracer dilution in large open channel flows: Analytical solution for the coefficient of variation of the depth-averaged concentration

    NASA Astrophysics Data System (ADS)

    Pannone, Marilena

    2014-03-01

    A large-time analytical solution is proposed for the spatial variance and coefficient of variation of the depth-averaged concentration due to instantaneous, cross sectionally uniform solute sources in pseudorectangular open channel flows. The mathematical approach is based on the use of the Green functions and on the Fourier decomposition of the depth-averaged velocities, coupled with the method of the images. The variance spatial trend is characterized by a minimum at the center of the mass and two mobile, decaying symmetrical peaks which, at very large times, are located at the inflexion points of the average Gaussian distribution. The coefficient of variation, which provides an estimate of the expected percentage deviation of the depth-averaged point concentrations about the section-average, exhibits a minimum at the center which decays like t-1 and only depends on the river diffusive time scale. The defect of cross-sectional mixing quickly increases with the distance from the center, and almost linearly at large times. Accurate numerical Lagrangian simulations were performed to validate the analytical results in preasymptotic and asymptotic conditions, referring to a particularly representative sample case for which cross-sectional depth and velocity measurements were known from a field survey. In addition, in order to discuss the practical usefulness of computing large-time concentration spatial moments in river flows, and resorting to directly measured input data, the order of magnitude of section-averaged concentrations and corresponding coefficients of variation was estimated in field conditions and for hypothetical contamination scenarios, considering a unit normalized mass impulsively injected across the transverse section of 81 U.S. rivers.

  3. Microstructure and stability of a lamellar liquid crystalline and gel phase formed by a polyglycerol ester mixture in dilute aqueous solution.

    PubMed

    Duerr-Auster, N; Kohlbrecher, J; Zuercher, T; Gunde, R; Fischer, P; Windhab, E

    2007-12-18

    The self-assembly behavior of a commercial mixture of polyglycerol fatty acid esters (PGE) and water is investigated as a function of temperature and surfactant content. The phase diagram of this pseudo-binary mixture was characterized using a combination of cross-polarized light and freeze-fracture electron microscopy (cryo-SEM), X-ray diffraction (XRD), small-angle neutron scattering (SANS), and differential scanning calorimetry (DSC). Our experiments show that the morphology of the supramolecular aggregates is lamellar and present in the form of a continuous or dispersed phase (multilamellar vesicles) depending on the water content of the system. Under the effect of temperature, the short- and long-range order of the bimolecular layers successively changes from a biphasic surfactant dispersion to a lamellar liquid-crystalline (Lalpha) and a stable lamellar gel phase (Lbeta) upon cooling; this transition is found to be irreversible. Formation of the lamellar aggregates can be related to the average molecular structure and shape factor of PGE. The stability of the resulting gel phase (Lbeta) appears to be due to the presence of small amounts of unreacted ionic co-surfactant, namely, fatty acid soaps, in this per se nonionic commercial mixture.

  4. Ionic Liquid versus Li(+) Aqueous Solutions: Water Dynamics near Bistriflimide Anions.

    PubMed

    Giammanco, Chiara H; Kramer, Patrick L; Fayer, Michael D

    2016-09-22

    The ultrafast dynamics of concentrated aqueous solutions of the salt lithium bistriflimide and ionic liquid (IL) 1-ethyl-3-methylimidazolium bistriflimide was studied using two-dimensional infrared (2D IR) vibrational echo and polarization-selective IR pump-probe techniques to monitor water's hydroxyl stretch. Two distinct populations of hydroxyl groups, with differing vibrational lifetimes, are detected in solution: those engaged in hydrogen bonding with other water molecules and those engaged in hydrogen bonding with the bistriflimide anion. Water molecules with the same hydrogen bond partner exhibit similar vibrational lifetimes in the two solutions. The reorientation dynamics of the anion-associated waters is also similar in form in the two solutions, showing a restricted wobbling-in-a-cone motion followed by a slower diffusive orientational randomization. However, the wobbling motions are much more angularly restricted in the IL solution. Spectral diffusion dynamics, which tracks the structural fluctuations of water's hydrogen bonds, is very different in the two solutions. Water in the IL solution experiences much faster fluctuations overall and shows a greater extent of motional narrowing, resulting in a larger homogeneously broadened component in the spectral line, compared to those in the aqueous lithium salt. Thus, even when the hydroxyls of water associate with the same anion in solution, the cation identity and extent of ionic ordering (i.e., salt solution vs IL) can play an important role in determining the structural fluctuations experienced by a small hydrogen-bonded solute. PMID:27580210

  5. Cationic surfactant adsorption states determined by the dependence of the electrophoretic mobility on dilution

    SciTech Connect

    Chang, C.H.

    1987-01-01

    A dilution method was devised in order to examine the dependence of the mobility of dilute aqueous coal dispersions on concentration. Mobility trends observed on dilution with water and the parent surfactant solution were interpreted in terms of desorption and adsorption of surfactant on coal. The dispersions were also studied by comparing the surface tension of surfactant solutions with the filtrates from a range of coal dispersions. The surfactants used were DTAB (Dodecyltrimethylammonium Bromide), CTAB (Cetyltrimethylammonium Bromide), ATLAS G-271 (N-Soya-N-ethyl morpholinium ethosulfate) and MERPOL-SE, (CH/sub 3/-(CH/sub 2/)/sub 24/-(OCH/sub 2/CH/sub 2/)/sub 8/-OH). The mobility of coal in the presence of cationic surfactant decreased as the dilution ratio increased and reach a constant value. It was also shown that the mobility remained near zero and constant if a non-ionic surfactant was used. On dilution with cationic surfactant solution, the mobility rose to a constant value at high dilution which was more than twice the aqueous asymptote suggesting the separate contribution of reversibility adsorbed surfactant. The structure of surfactant was another effect which controlled the adsorption mechanism. The two major properties of surfactant structure were the hydrophobicity and steric hindrance. The results also implied that hydrophobic tail-adsorbed was the dominant mechanism in contrast to the model which was proposed in earlier studies. Comparison of surface tension between pure surfactant solution and the filtrate from coal/surfactant solution indicated that the surfactants did not all act alike in some cases. Natural surfactant had been desorbed or eluted and in some cases surfactant had been adsorbed.

  6. Critical phenomena and thermodynamics of dilute aqueous sodium chloride to 823 K

    PubMed Central

    Pitzer, Kenneth S.; Li, Yi-gui

    1984-01-01

    Semiempirical equations are developed that represent the behavior of dilute solutions of NaCl in water (steam) in the range 723-823 K where ion pairing is extensive. This supplements the equations given earlier for more concentrated solutions. In this temperature range the system NaCl/H2O shows critical behavior with two phases below the critical pressure. The equations for the dilute solutions yield critical behavior. Though the equations for concentrated solutions do not yield critical behavior at the critical pressure, only a very small interpolation function is required to connect smoothly the two equations. The ion-pairing equilibrium constants are reported as well as the Gibbs energies of hydration for both ions and ion pairs. PMID:16593423

  7. Water and energy as inseparable twins for sustainable solutions.

    PubMed

    Hofman, Jan; Hofman-Caris, Roberta; Nederlof, Maarten; Frijns, Jos; van Loosdrecht, Mark

    2011-01-01

    Although the water cycle is only a minor contributor to the energy demand in society, it is a matter of good housekeeping to minimize the energy need within a sustainable water cycle. Wastewater treatment should not only be applied to purify the water, but also recover the energy present in this water, as well as to recover essential elements like nitrogen and phosphorus. From an energy analysis of the Dutch water cycle it is concluded that creating an energy neutral water cycle by using the heat content or by making use of the organic load of wastewater is within hands. PMID:21245558

  8. Safety and efficacy of aspartame-based liquid versus sucrose-based liquids used for dilution in oral sodium phosphate solutions for colonoscopy preparations.

    PubMed

    Chamberlain, Sherman M; Balart, J Carter; Sideridis, Kostas; Salek, Jefrey; Sridhar, Subbaramiah; Thompson, William O

    2007-11-01

    The aim of this study was to investigate whether an oral sodium phosphate solution (OSPS) mixed with aspartame-based clear liquids as the diluent would yield improved colon cleansing results compared to an OSPS mixed with sucrose-based liquids as the diluent. Fifty-one patients undergoing colonoscopy were prospectively randomized into two groups to receive different OSPS colonoscopy preparations, with sucrose-based or aspartame-based liquids used as diluents. The primary end point was the quality of the colonoscopy preparation and secondary end points were serum electrolytes before and after preparations. No significant difference in colonoscopy preparation quality was seen between the two OSPS diluent groups (Mantel-Haenzel chi (2) = 0.795, P = 0.484). There were no significant differences in mean electrolyte shifts of sodium, potassium, blood urea nitrogen (BUN), creatinine (Cr), or BUN/Cr ratios between the two groups. There was a statistically significant increase in serum phosphorous in the aspartame-based group compared to the sucrose-based diluent group (P = 0.021). In conclusion, there was no clinically detectable difference in colonoscopy preparation quality between the two OSPS diluent groups. This study suggests that passive fluid transport by aquaporins may well be the major mediator of fluid shifts in the study subjects. This result suggests the potential importance of aquaporins and minimizes the importance of sodium glucose cotransporter SGLT1 in fluid and electrolyte transport in the human gastrointestinal tract. Aspartame or its constituent amino acids may enhance phosphate absorption across the human small intestine.

  9. Small Angle Neutron Scattering Study of Conformation of Oligo(ethylene glycol) Grafted Polystyrene in Dilute Solutions: Effect of the Backbone Length

    SciTech Connect

    Cheng, Gang; Hong, Kunlun; Hua, Fengjun; Melnichenko, Yuri B; Wignall, George D; Mays, Jimmy

    2008-01-01

    The conformation and clusterization of comb like polymers of polystyrene densely grafted with oligo(ethylene glycol) (OEG) side chains in 1.0 wt% solutions of D2O, toluene-d8 and methanol-d4 was investigated as a function of the degree of polymerization (DP) of the backbone by small angle neutron scattering (SANS). Each side chain had four EG repeat units and the DP of the polystyrene backbone was varied from 8 to 85. The global conformation of the polymers in toluene and methanol was shown to assume ellipsoidal, cylindrical or worm-like chain morphologies with increasing DP of the polystyrene backbone. At the same time, in D2O, the polymer conformation was described by the form factor of rigid cylinders. The second viral coefficient was measured for the polymer with a DP of 85 in all three solvents and the solvent quality of toluene, methanol and D2O was identified as good, marginal and poor for this polymer. Due to a poor solvent quality, the PS backbone (DP = 85) is partially collapsed in D2O whereas it is moderately expanded in toluene and methanol. Polymers with the DP of 8 were found to aggregate into clusters in all three solvents, with the characteristic size between 100 and 200 ?and a fractal dimension of 2. With increase of the DP, the clusters diminished in D2O and completely disappeared in toluene and methanol. This observation suggests that the clusterization of these short side-chain polymers is caused by end group and hydrogen bonding interactions between different chains.

  10. Novel Regenerated Solvent Extraction Processes for the Recovery of Carboxylic Acids or Ammonia from Aqueous Solutions Part II. Recovery of Ammonia from Sour Waters

    SciTech Connect

    Poole, L.J.; King, C.J.

    1990-03-01

    Two novel regenerated solvent extraction processes are examined. The first process has the potential to reduce the energy costs inherent in the recovery of low-volatility carboxylic acids from dilute aqueous solutions. The second process has the potential for reducing the energy costs required for separate recovery of ammonia and acid gases (e.g. CO{sub 2} and H{sub 2}S) from industrial sour waters. The recovery of carboxylic acids from dilute aqueous solution can be achieved by extraction with tertiary amines. An approach for regeneration and product recovery from such extracts is to back-extract the carboxylic acid with a water-soluble, volatile tertiary amine, such as trimethylamine. The resulting trimethylammonium carboxylate solution can be concentrated and thermally decomposed, yielding the product acid and the volatile amine for recycle. Experimental work was performed with lactic acid, SUCCiOlC acid, and fumaric acid. Equilibrium data show near-stoichiometric recovery of the carboxylic acids from an organic solution of Alamine 336 into aqueous solutions of trimethylamine. For fumaric and succinic acids, partial evaporation of the aqueous back extract decomposes the carboxylate and yields the acid product in crystalline form. The decomposition of aqueous solutions of trimethylammonium lactates was not carried out to completion, due to the high water solubility of lactic acid and the tendency of the acid to self-associate. The separate recovery of ammonia and acid gases from sour waters can be achieved by combining steam-stripping of the acid gases with simultaneous removal of ammonia by extraction with a liquid cation exchanger. The use of di-2,4,4-trimethylpentyl phosphinic acid as the liquid cation exchanger is explored in this work. Batch extraction experiments were carried out to measure the equilibrium distribution ratio of ammonia between an aqueous buffer solution and an organic solution of the phosphinic acid (0.2N) in Norpar 12. The concentration

  11. Technology Solutions Case Study: Heat Pump Water Heater Retrofit

    SciTech Connect

    none,

    2012-08-01

    In this project, Pacific Northwest National Laboratory studied heat pump water heaters, an efficient, cost-effective alternative to traditional electric resistance water heaters that can improve energy efficiency by up to 62%.

  12. Chemical repair of base lesions, AP-sites, and strand breaks on plasmid DNA in dilute aqueous solution by ascorbic acid

    SciTech Connect

    Hata, Kuniki; Urushibara, Ayumi; Yamashita, Shinichi; Shikazono, Naoya; Yokoya, Akinari; Katsumura, Yosuke

    2013-05-03

    Highlights: •We report a novel mechanism of radiation protection of DNA by chemical activity of ascorbic acid. •The “chemical repair” of DNA damage was revealed using biochemical assay and chemical kinetics analysis. •We found that ascorbic acid significantly repairs precursors of nucleobase lesions and abasic sites. •However, ascorbic acid seldom repairs precursors of DNA-strand breaks. -- Abstract: We quantified the damage yields produced in plasmid DNA by γ-irradiation in the presence of low concentrations (10–100 μM) of ascorbic acid, which is a major antioxidant in living systems, to clarify whether it chemically repairs radiation damage in DNA. The yield of DNA single strand breaks induced by irradiation was analyzed with agarose gel electrophoresis as conformational changes in closed circular plasmids. Base lesions and abasic sites were also observed as additional conformational changes by treating irradiated samples with glycosylase proteins. By comparing the suppression efficiencies to the induction of each DNA lesion, in addition to scavenging of the OH radicals derived from water radiolysis, it was found that ascorbic acid promotes the chemical repair of precursors of AP-sites and base lesions more effectively than those of single strand breaks. We estimated the efficiency of the chemical repair of each lesion using a kinetic model. Approximately 50–60% of base lesions and AP-sites were repaired by 10 μM ascorbic acid, although strand breaks were largely unrepaired by ascorbic acid at low concentrations. The methods in this study will provide a route to understanding the mechanistic aspects of antioxidant activity in living systems.

  13. New steady-state models for water-limited cropping systems using saline irrigation waters: Analytical solutions and applications

    NASA Astrophysics Data System (ADS)

    Skaggs, T. H.; Anderson, R. G.; Corwin, D. L.; Suarez, D. L.

    2014-12-01

    Due to the diminishing availability of good quality water for irrigation, it is increasingly important that irrigation and salinity management tools be able to target submaximal crop yields and support the use of marginal quality waters. In this work, we present a steady-state irrigated systems modeling framework that accounts for reduced plant water uptake due to root zone salinity. Two new explicit, closed-form analytical solutions for the root zone solute concentration profile are obtained, corresponding to two alternative functional forms of the uptake reduction function. The solutions express a general relationship between irrigation water salinity, irrigation rate, crop salt tolerance, crop transpiration, and (using standard approximations) crop yield. Example applications are illustrated, including the calculation of irrigation requirements for obtaining targeted submaximal yields, and the generation of crop-water production functions for varying irrigation waters, irrigation rates, and crops. Model predictions are shown to be mostly consistent with existing models and available experimental data. Yet the new solutions possess clear advantages over available alternatives, including: (i) the new solutions were derived from a complete physical-mathematical description of the system, rather than based on an ad hoc formulation; (ii) the new analytical solutions are explicit and can be evaluated without iterative techniques; (iii) the solutions permit consideration of two common functional forms of salinity induced reductions in crop water uptake, rather than being tied to one particular representation; and (iv) the utilized modeling framework is compatible with leading transient-state numerical models.

  14. Effect of Honey Solution and Water Acquisition on Survival of Starved Solenopsis Mealybug, Phenacoccus solenopsis

    PubMed Central

    Huang, Fang; Wang, Feifei; Lu, Yaobin; Zhang, Pengjun; Zhang, Jinming; Zhang, Zhijun; Li, Weidi; Lin, Wencai; Bei, Yawei

    2014-01-01

    The current study examined the effects of honey solution and water access on feeding behavior and survival of starving solenopsis mealybugs, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae). The electrical penetration graph technique and an artificial membrane system were used to check whether P. solenopsis could imbibe free water or other liquid, such as the honey solution used here, in its natural environment. The recorded electrical penetration graph waveforms revealed that P. solenopsis could continuously imbibe water-honey solution for several hours, which indicated that honey solution and water acquisition could possibly occur when P. solenopsis had access to such liquids in its natural environment. Waveforms of water-honey solution feeding alternated between two distinct feeding phases in a regular pattern, which was assumed to reflect inherent habits of feeding attempts. The effects of honey solution and water acquisition on survival of P. solenopsis was also examined. Comparison between P. solenopsis in different treatments (starved, water feeding, honey solution feeding, and cotton plant feeding) suggested that 1) P. solenopsis could accept but did not favor feeding on water or the honey solution, and 2) this feeding could prolong its survival, but had no effect on body size. PMID:25373148

  15. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Making alcohol or water solutions of denaturants. 19.385 Section 19.385 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO... alcohol or water solutions of denaturants. If a proprietor uses a denaturant that is difficult to...

  16. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Making alcohol or water solutions of denaturants. 19.385 Section 19.385 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO... alcohol or water solutions of denaturants. If a proprietor uses a denaturant that is difficult to...

  17. Evaluation of Polyuria: The Roles of Solute Loading and Water Diuresis.

    PubMed

    Bhasin, Bhavna; Velez, Juan Carlos Q

    2016-03-01

    Polyuria, defined as daily urine output in excess of 3.0 to 3.5L/d, can occur due to solute or water diuresis. Solute-induced polyuria can be seen in hospitalized patients after a high solute load from exogenous protein administration or following relief of urinary obstruction. Similar clinical scenarios are rarely encountered in the outpatient setting. We describe a case of polyuria due to high solute ingestion and excessive water intake leading to a mixed picture of solute and water diuresis. Restriction of the daily solute load and water intake resulted in complete resolution of polyuria. Determination of the daily excreted urinary osmoles may yield important clues to the cause of polyuria and should be included in the routine workup of polyuria.

  18. Evaluation of Polyuria: The Roles of Solute Loading and Water Diuresis.

    PubMed

    Bhasin, Bhavna; Velez, Juan Carlos Q

    2016-03-01

    Polyuria, defined as daily urine output in excess of 3.0 to 3.5L/d, can occur due to solute or water diuresis. Solute-induced polyuria can be seen in hospitalized patients after a high solute load from exogenous protein administration or following relief of urinary obstruction. Similar clinical scenarios are rarely encountered in the outpatient setting. We describe a case of polyuria due to high solute ingestion and excessive water intake leading to a mixed picture of solute and water diuresis. Restriction of the daily solute load and water intake resulted in complete resolution of polyuria. Determination of the daily excreted urinary osmoles may yield important clues to the cause of polyuria and should be included in the routine workup of polyuria. PMID:26687922

  19. A Novel Approach for Direct Measurement of Cumulative Water and Solute Mass Fluxes using a Passive Surface Water Flux Meter

    NASA Astrophysics Data System (ADS)

    Padowski, J. C.; Jawitz, J. W.; Hatfield, K.; Annable, M. D.; Cho, J.; Klammler, H.

    2005-12-01

    This work describes the development of a novel technique for passive measurement of pollutant loads in flowing surface water systems. Recent changes to the Clean Water Act have prompted a major initiative for the development of a national list of impaired surface waters. According to the law, every state is now responsible for defining the use of each water body and creating a Total Maximum Daily Load (TMDL) to regulate all pollutant loads entering these systems. Current methods for determining pollutant loads typically involve collecting separate instantaneous measurements of water velocities and solute concentrations at discrete points in space and time. The data must be combined, interpolated and integrated after collection to arrive at estimates of local cumulative solute flux and discharge. The frequency with which these parameters are measured typically rely upon the availability of resources (time, money, manpower, etc.) and are often undersampled. A method is presented here for direct measurement of cumulative surface water flux (discharge) and solute flux using a Passive Surface Water Flux Meter (PSFM). The PSFM is designed to directly measure local cumulative water and solute mass fluxes in surface water flow without any active components transmitting or logging data over time. This passive integration of water and solute mass fluxes eliminates the need for independent water flux and concentration measurements and any additional computations. Laboratory trials under steady state and transient conditions were used to test the appropriateness of the PSFM as a device for collecting water quality data. Results from steady state experiments verified the ability of PSFM to accurately measure cumulative water and solute mass flux. Preliminary results from investigations under transient flow conditions also showed promise for measuring pollutant loads in natural systems with this device.

  20. Multinuclear NMR studies of water in solutions of simple carbohydrates.

    NASA Astrophysics Data System (ADS)

    Belton, P. S.; Ring, S. G.; Botham, R. L.; Hills, B. P.

    Oxygen-17 water relaxation is reported for the series of α(1 → 4) linked glucans, glucose to maltoheptaose over a wide range of sugar concentrations. The results can be interpreted quantitatively using a two-site exchange model where the 'bound' water reorients anisotropically. The effect of carbohydrate chain length on the fast and slow correlation times characterizing the bound water reorientation is discussed. Comparison is also made with the correlation times derived using deuterium relaxation.

  1. Is Storage a Solution to End Water Shortage?

    NASA Astrophysics Data System (ADS)

    Narayanan, M.

    2009-12-01

    Water shortage is a problem of supply and demand. Some authors refer to it as Water Scarcity. The author has discussed this in his previous presentation at the 2008 AGU International Conference. Part of it is reproduced here for purposes of clarification. It is important to recognize that water is essential for the survival of all life on earth. Many water-rich states have thought of water conservation as an art that is practiced mainly in the arid states. But one has to recite the famous quote: “You will never miss water till the well runs dry.” Researchers have also concluded that quantity deficiency experienced by groundwater supplies are affecting many communities around the world. Furthermore federal regulations pertaining to the quality of potable or drinking water have become more stringent (Narayanan, 2008). One must observe that water conservation schemes and efficient utilization practices also benefit the environment to a large extent. These water conservation practicies indeed have a short payback period althought it may seem that there is a heavy initial investment is required. Research scientists have studied MARR (Mean Annual River Runoff) pattern over the years and have arrived at some significant conclusions. Vörsömarty and other scientists have indicated that water scarcity exists when the demand to supply ratio exceeds the number 0.4. (Vörsömarty, 2005). Furthermore other researchers claim to have documented a six-fold increase in water use in the United States during the last century. It is interesting to note that the population of the United States has hardly doubled during the last century. This obviously, is indicative of higher living standards. Nevertheless, it also emphasizes an urgent need for establishing a strong, sound, sensible and sustainable management program for utilizing the available water supplies efficiently (Narayanan, 2008). Author of the 1998 book, Last Oasis: Facing Water Scarcity, Dr. Sandra Postel predicts big

  2. A selective fluorescent probe for the detection of Cd(2+) in different buffer solutions and water.

    PubMed

    Xu, Zheng; Li, Guoqiang; Ren, Yuan-Yuan; Huang, Hua; Wen, Xiaoping; Xu, Qiang; Fan, Xiaotian; Huang, Zhao; Huang, Junhai; Xu, Lin

    2016-07-26

    A simple fluorescent probe NHQ based on quinoline was successfully prepared via one-step synthesis. The probe NHQ exhibited "turn-on" fluorescence and excellent selectivity toward Cd(2+) in different buffer solutions such as Tris-HCl buffer solution, HEPES buffer solution, and PBS buffer solution, and even in water. Moreover, the binding model of NHQ with Cd(2+) was definitely confirmed by the single crystal X-ray diffraction studies of the complex. PMID:27397654

  3. A selective fluorescent probe for the detection of Cd(2+) in different buffer solutions and water.

    PubMed

    Xu, Zheng; Li, Guoqiang; Ren, Yuan-Yuan; Huang, Hua; Wen, Xiaoping; Xu, Qiang; Fan, Xiaotian; Huang, Zhao; Huang, Junhai; Xu, Lin

    2016-07-26

    A simple fluorescent probe NHQ based on quinoline was successfully prepared via one-step synthesis. The probe NHQ exhibited "turn-on" fluorescence and excellent selectivity toward Cd(2+) in different buffer solutions such as Tris-HCl buffer solution, HEPES buffer solution, and PBS buffer solution, and even in water. Moreover, the binding model of NHQ with Cd(2+) was definitely confirmed by the single crystal X-ray diffraction studies of the complex.

  4. Isolation of nonvolatile, organic solutes from natural waters by zeotrophic distillation of water from N,N-dimethylformamide

    USGS Publications Warehouse

    Leenheer, J.A.; Brown, P.A.; Stiles, E.A.

    1987-01-01

    Nonvolatile, organic solutes that comprise the dissolved organic carbon (DOC) in saline waters were isolated by removal of the water by distillation from a N,N-dimethylformamideformic acid-acetonitrile mixture. Salts isolated with the DOC were removed by crystallization of sodium chloride and sodium sulfate from the solvent mixture, removal of silicic acid by acidification and precipitation, removal of boric acid by methylation and volatilization, and removal of phosphate by zinc acetate precipitation. Chemical alteration of the organic solutes was minimized during evaporative concentration steps by careful control of acid concentrations in the solvent mixture and was minimized during drying by conversion of the samples to pyridinium and sodium salts. Recoveries of various hydrophilic organic standards from aqueous salt solutions and recoveries of natural organic solutes from various water samples varied from 60 to 100%. Losses of organic solutes during the isolation procedure were nonselective and related to the number of salt- and precipitate-washing cycles in the procedure.

  5. Diet change—a solution to reduce water use?

    NASA Astrophysics Data System (ADS)

    Jalava, M.; Kummu, M.; Porkka, M.; Siebert, S.; Varis, O.

    2014-07-01

    Water and land resources are under increasing pressure in many parts of the globe. Diet change has been suggested as a measure to contribute to adequate food security for the growing population. This paper assesses the impact of diet change on the blue and green water footprints of food consumption. We first compare the water consumption of the current diets with that of a scenario where dietary guidelines are followed. Then, we assess these footprints by applying four scenarios in which we gradually limit the amount of protein from animal products to 50%, 25%, 12.5% and finally 0% of the total protein intake. We find that the current water use at the global scale would be sufficient to secure a recommended diet and worldwide energy intake. Reducing the animal product contribution in the diet would decrease global green water consumption by 6%, 11%, 15% and 21% within the four applied scenarios, while for blue water, the reductions would be 4%, 6%, 9% and 14%. In Latin America, Europe, Central and Eastern Asia and Sub-Saharan Africa, diet change mainly reduces green water use, while in the Middle East region, North America, Australia and Oceania, both blue and green water footprints decrease considerably. At the same time, in South and Southeast Asia, diet change does not result in decreased water use. Our results show that reducing animal products in the human diet offers the potential to save water resources, up to the amount currently required to feed 1.8 billion additional people globally; however, our results show that the adjustments should be considered on a local level.

  6. Changes in Lignin and Polysaccharide Components in 13 Cultivars of Rice Straw following Dilute Acid Pretreatment as Studied by Solution-State 2D 1H-13C NMR.

    PubMed

    Teramura, Hiroshi; Sasaki, Kengo; Oshima, Tomoko; Aikawa, Shimpei; Matsuda, Fumio; Okamoto, Mami; Shirai, Tomokazu; Kawaguchi, Hideo; Ogino, Chiaki; Yamasaki, Masanori; Kikuchi, Jun; Kondo, Akihiko

    2015-01-01

    A renewable raw material, rice straw is pretreated for biorefinery usage. Solution-state two-dimensional (2D) 1H-13 C hetero-nuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, was used to analyze 13 cultivars of rice straw before and after dilute acid pretreatment, to characterize general changes in the lignin and polysaccharide components. Intensities of most (15 of 16) peaks related to lignin aromatic regions, such as p-coumarate, guaiacyl, syringyl, p-hydroxyphenyl, and cinnamyl alcohol, and methoxyl, increased or remained unchanged after pretreatment. In contrast, intensities of most (11 of 13) peaks related to lignin aliphatic linkages or ferulate decreased. Decreased heterogeneity in the intensities of three peaks related to cellulose components in acid-insoluble residues resulted in similar glucose yield (0.45-0.59 g/g-dry biomass). Starch-derived components showed positive correlations (r = 0.71 to 0.96) with glucose, 5-hydroxymethylfurfural (5-HMF), and formate concentrations in the liquid hydrolysates, and negative correlations (r = -0.95 to -0.97) with xylose concentration and acid-insoluble residue yield. These results showed the fate of lignin and polysaccharide components by pretreatment, suggesting that lignin aromatic regions and cellulose components were retained in the acid insoluble residues and starch-derived components were transformed into glucose, 5-HMF, and formate in the liquid hydrolysate.

  7. Changes in Lignin and Polysaccharide Components in 13 Cultivars of Rice Straw following Dilute Acid Pretreatment as Studied by Solution-State 2D 1H-13C NMR

    PubMed Central

    Teramura, Hiroshi; Sasaki, Kengo; Oshima, Tomoko; Aikawa, Shimpei; Matsuda, Fumio; Okamoto, Mami; Shirai, Tomokazu; Kawaguchi, Hideo; Ogino, Chiaki; Yamasaki, Masanori; Kikuchi, Jun; Kondo, Akihiko

    2015-01-01

    A renewable raw material, rice straw is pretreated for biorefinery usage. Solution-state two-dimensional (2D) 1H-13 C hetero-nuclear single quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy, was used to analyze 13 cultivars of rice straw before and after dilute acid pretreatment, to characterize general changes in the lignin and polysaccharide components. Intensities of most (15 of 16) peaks related to lignin aromatic regions, such as p-coumarate, guaiacyl, syringyl, p-hydroxyphenyl, and cinnamyl alcohol, and methoxyl, increased or remained unchanged after pretreatment. In contrast, intensities of most (11 of 13) peaks related to lignin aliphatic linkages or ferulate decreased. Decreased heterogeneity in the intensities of three peaks related to cellulose components in acid-insoluble residues resulted in similar glucose yield (0.45–0.59 g/g-dry biomass). Starch-derived components showed positive correlations (r = 0.71 to 0.96) with glucose, 5-hydroxymethylfurfural (5-HMF), and formate concentrations in the liquid hydrolysates, and negative correlations (r = –0.95 to –0.97) with xylose concentration and acid-insoluble residue yield. These results showed the fate of lignin and polysaccharide components by pretreatment, suggesting that lignin aromatic regions and cellulose components were retained in the acid insoluble residues and starch-derived components were transformed into glucose, 5-HMF, and formate in the liquid hydrolysate. PMID:26083431

  8. A diffusive anomaly of water in aqueous sodium chloride solutions at low temperatures.

    PubMed

    Kim, Jun Soo; Yethiraj, Arun

    2008-02-14

    Molecular dynamics simulations are presented for the self-diffusion coefficient of water in aqueous sodium chloride solutions. At temperatures above the freezing point of pure water, the self-diffusion coefficient is a monotonically decreasing function of salt concentration. Below the freezing point of pure water, however, the self-diffusion coefficient is a non-monotonic function of salt concentration, showing a maximum at approximately one molal salt. This suggests that sodium chloride, which is considered a structure-making salt at room temperature, becomes a structure-breaking salt at low temperatures. A qualitative understanding of this effect can be obtained by considering the effect of ions on the residence time of water molecules near other water molecules. A consideration of the freezing point depression of aqueous sodium chloride solutions suggests that the self-diffusion coefficient of water in supercooled sodium chloride solutions is always higher than that in pure (supercooled) water at the same temperature.

  9. DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

    SciTech Connect

    Kishore K. Mohanty

    2003-07-01

    There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have conducted adsorption, phase behavior, interfacial tension (IFT) and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases IFT with a minimum at about 0.2 M. Addition of surfactant decreases IFT further. In the absence of surfactant the minerals are oil-wet after aging with crude oil. Addition of surfactant solution decreases the contact angle to intermediate-wet for many surfactants and water-wet for one surfactant. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Plans for the next quarter include conducting core adsorption, phase behavior, wettability and mobilization studies.

  10. Helium dilution refrigeration system

    DOEpatents

    Roach, Patrick R.; Gray, Kenneth E.

    1988-01-01

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains .sup.3 He and .sup.4 He liquids which are precooled by a coupled container containing .sup.3 He liquid, enabling the phase separation of a .sup.3 He rich liquid phase from a dilute .sup.3 He-.sup.4 He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the .sup.3 He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute .sup.3 He-.sup.4 He liquid phase.

  11. Helium dilution refrigeration system

    DOEpatents

    Roach, P.R.; Gray, K.E.

    1988-09-13

    A helium dilution refrigeration system operable over a limited time period, and recyclable for a next period of operation is disclosed. The refrigeration system is compact with a self-contained pumping system and heaters for operation of the system. A mixing chamber contains [sup 3]He and [sup 4]He liquids which are precooled by a coupled container containing [sup 3]He liquid, enabling the phase separation of a [sup 3]He rich liquid phase from a dilute [sup 3]He-[sup 4]He liquid phase which leads to the final stage of a dilution cooling process for obtaining low temperatures. The mixing chamber and a still are coupled by a fluid line and are maintained at substantially the same level with the still cross sectional area being smaller than that of the mixing chamber. This configuration provides maximum cooling power and efficiency by the cooling period ending when the [sup 3]He liquid is depleted from the mixing chamber with the mixing chamber nearly empty of liquid helium, thus avoiding unnecessary and inefficient cooling of a large amount of the dilute [sup 3]He-[sup 4]He liquid phase. 2 figs.

  12. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Making alcohol or water... alcohol or water solutions of denaturants. If a proprietor uses a denaturant that is difficult to dissolve... water prior to its use in the production of denatured spirits. However, the proof of the...

  13. PTR-MS study of esters in water and water/ethanol solutions

    NASA Astrophysics Data System (ADS)

    Aprea, Eugenio; Biasioli, Franco; Märk, Tilmann D.; Gasperi, Flavia

    2007-04-01

    Esters strongly influence the perceived aroma of alcoholic beverages and their rapid monitoring can play an important role in the quality control of these products. Proton transfer reaction mass spectrometry (PTR-MS) allows the rapid and non invasive monitoring of foodstuff but there is still a lack of information about the proton transfer induced fragmentation and on the effect of high ethanol concentration. PTR-MS fragmentation patterns of 21 esters are reported, most of them for the first time. For linear methyl and ethyl esters the fragmentation dependence on E/N was also evaluated. Acetate esters, with exception of methyl acetate, show as main peaks the characteristic fragment ions at m/z 61 and m/z 43, whereas propanoate esters, but methyl propanoate, exhibit as main peaks the typical signals at m/z 75 and m/z 57. For all the other esters, here reported, the spectra are dominated by the protonated molecular ion. For methyl and ethyl esters we also report, in many cases for the first time, the water-solution/air partition coefficients (Henry's law constant) and the ethanol-solution/air partition coefficients at different ethanol concentrations. The information provided in this work may be useful as a basis for further studies for the identification and quantification of esters in the headspace of alcoholic beverages extending the application field of PTR-MS.

  14. The effects of replacing the water model while decoupling water-water and water-solute interactions on computed properties of simple salts.

    PubMed

    Li, Jicun; Wang, Feng

    2016-07-28

    The effects of decoupling the water-water and water-solute interactions are studied with selected mono-valent ions as the solute. Using the ion-water cross terms developed for the BLYPSP-4F water model, we replaced the water potential with WAIL, TIP4P, and TIP3P without changing the ion-water parameters. When the adaptive force matching (AFM) derived BLYPSP-4F model is replaced by the other AFM derived WAIL model, the difference in ion properties, such as hydration free energies, radial distribution functions, relative diffusion constants, is negligible, demonstrating the feasibility for combining AFM parameters from different sources. Interestingly, when the AFM-derived ion-water cross-terms are used with a non-AFM based water model, only small changes in the ion properties are observed. The final combined models with TIP3P or TIP4P water reproduce the salt hydration free energies within 6% of experiments. The feasibility of combining AFM models with other non-AFM models is of significance since such combinations allow more complex systems to be studied without specific parameterization. In addition, the study suggests an interesting prospect of reusing the cross-terms when a part of a general force field is replaced with a different model. The prevailing practice, which is to re-derive all cross-terms with combining rules, may not have been optimal. PMID:27475375

  15. The effects of replacing the water model while decoupling water-water and water-solute interactions on computed properties of simple salts

    NASA Astrophysics Data System (ADS)

    Li, Jicun; Wang, Feng

    2016-07-01

    The effects of decoupling the water-water and water-solute interactions are studied with selected mono-valent ions as the solute. Using the ion-water cross terms developed for the BLYPSP-4F water model, we replaced the water potential with WAIL, TIP4P, and TIP3P without changing the ion-water parameters. When the adaptive force matching (AFM) derived BLYPSP-4F model is replaced by the other AFM derived WAIL model, the difference in ion properties, such as hydration free energies, radial distribution functions, relative diffusion constants, is negligible, demonstrating the feasibility for combining AFM parameters from different sources. Interestingly, when the AFM-derived ion-water cross-terms are used with a non-AFM based water model, only small changes in the ion properties are observed. The final combined models with TIP3P or TIP4P water reproduce the salt hydration free energies within 6% of experiments. The feasibility of combining AFM models with other non-AFM models is of significance since such combinations allow more complex systems to be studied without specific parameterization. In addition, the study suggests an interesting prospect of reusing the cross-terms when a part of a general force field is replaced with a different model. The prevailing practice, which is to re-derive all cross-terms with combining rules, may not have been optimal.

  16. The electrostatic response of water to neutral polar solutes: Implications for continuum solvent modeling

    NASA Astrophysics Data System (ADS)

    Muddana, Hari S.; Sapra, Neil V.; Fenley, Andrew T.; Gilson, Michael K.

    2013-06-01

    Continuum solvation models are widely used to estimate the hydration free energies of small molecules and proteins, in applications ranging from drug design to protein engineering, and most such models are based on the approximation of a linear dielectric response by the solvent. We used explicit-water molecular dynamics simulations with the TIP3P water model to probe this linear response approximation in the case of neutral polar molecules, using miniature cucurbituril and cyclodextrin receptors and protein side-chain analogs as model systems. We observe supralinear electrostatic solvent responses, and this nonlinearity is found to result primarily from waters' being drawn closer and closer to the solutes with increased solute-solvent electrostatic interactions; i.e., from solute electrostriction. Dielectric saturation and changes in the water-water hydrogen bonding network, on the other hand, play little role. Thus, accounting for solute electrostriction may be a productive approach to improving the accuracy of continuum solvation models.

  17. Applications of isotopes to tracing sources of solutes and water in shallow systems

    USGS Publications Warehouse

    Kendall, Carol; Krabbenhoft, David P.

    1995-01-01

    New awareness of the potential danger to water supplies posed by the use of agricultural chemicals has focused attention on the nature of groundwater recharge and the mobility of various solutes, especially nitrate and pesticides, in shallow systems. A better understanding of hydrologic flowpaths and solute sources is required to determine the potential impact of sources of contamination on water supplies, to develop management practices for preserving water quality, and to develop remediation plans for sites that are already contaminated. In many cases, environmental isotopes can be employed as 'surgical tools' for answering very specific questions about water and solute sources. Isotopic data can often provide more accurate information about the system than hydrologic measurements or complicated hydrologic models. This note focuses on practical and cost-effective examples of how naturally-occurring isotopes can be used to track water and solutes as they move through shallow systems.

  18. How to identify water from thickener aqueous solutions by touch

    PubMed Central

    Nonomura, Yoshimune; Miura, Taku; Miyashita, Takaaki; Asao, Yuka; Shirado, Hirokazu; Makino, Yasutoshi; Maeno, Takashi

    2012-01-01

    Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner's corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment. PMID:22072449

  19. Osmotic diuresis-induced hypernatremia: better explained by solute-free water clearance or electrolyte-free water clearance?

    PubMed

    Popli, Subhash; Tzamaloukas, Antonios H; Ing, Todd S

    2014-01-01

    Hypernatremia may result from inadequate water intake, excessive water loss or a combination of the two. Osmotic diuresis leads to losses of both solute and water. The relationship between solute and water losses determines the resulting changes in serum osmolality and sodium concentration. Total solute loss is routinely higher than loss of water in osmotic diuresis. Theoretically, then, decreases in serum osmolality (and serum sodium concentration) should follow. In clinical situations of osmotic diuresis, however, reduction in osmolality can take place, but not reduction in serum sodium concentration. It is of note that serum sodium concentration changes are related to urinary losses of sodium and potassium but not to the loss of total solute. In osmotic diuresis, the combined loss of sodium and potassium per liter of urine is lower than the concurrent serum sodium level. Consequently, hypernatremia can ensue. A patient who presented with osmotic diuresis and hypernatremia is described here. In this patient, we have shown that electrolyte-free water clearance is a better index of the effect of osmotic diuresis on serum sodium concentration than the classic solute-free water clearance.

  20. An investigation of spectral characteristics of water-glucose solutions

    NASA Astrophysics Data System (ADS)

    Lastovskaia, Elena A.; Gorbunova, Elena V.; Chertov, Aleksandr N.; Korotaev, Valery V.

    2016-04-01

    One of the problems of modern medical device engineering is the development of an instrument for non-invasive monitoring of glucose levels in the blood. The urgency of this task is ensured by the following facts: the increase in the incidence of diabetes, the need for regular monitoring of blood sugar, and pain of modern methods of glycemia measurement. The problem can be solved with the help of a spectrophotometric method. This report is devoted to the investigation of spectral characteristics of glucose solution with various molar concentrations. The authors proposed the methodology of experimental research and data processing algorithm. The results of the experimental studies confirmed potential opportunity of blood sugar control by spectrophotometric method. Further research is expected to continue by the way of complication of the composition of the object from an aqueous solution of glucose to biological object.

  1. Structural Order of Water Molecules around Hydrophobic Solutes: Length-Scale Dependence and Solute-Solvent Coupling.

    PubMed

    Hande, Vrushali R; Chakrabarty, Suman

    2015-08-27

    It has been suggested that the structure and thermodynamics of the water molecules in the hydration layer of simple hydrophobic solutes undergo an order-disorder transition around a nanometer length-scale of the solute size. Using extensive atomistic molecular dynamics (MD) and replica exchange molecular dynamics (REMD) simulation studies, we have probed this order-disorder transition around model hydrophobic solutes of varying size and shape (spherical, planar, and linear), as well as flexible hydrophobic homopolymer chains (n-alkanes), where the conformational fluctuations are likely to create both spatial and temporal heterogeneity on the solvent accessible surface. We have explored the structural response of the water molecules in the hydration shell due to the local variations of the length-scale (or curvature) upon hydrophobic collapse and/or local conformational changes of these polymers. We have shown that the tetrahedral order of the water molecules in the hydration shell is practically independent of the polymer size in the extended state of the polymer due to the availability of a subnanometer cross-sectional length-scale, allowing the water molecules to form hydrogen bonds around the polymer chain. Beyond a certain length of the polymer chains, the collapsed states (associated with larger solute length-scale) start to induce disorder in the surface water molecules. We demonstrate that the local structure (both local number density and tetrahedral order) of the hydration layer is dynamically coupled to the local topology of the polymer. Thus, we envisage that in a flexible (bio)polymer, the hydration shell properties will be sensitive to the local conformational state of the molecule (both spatially and temporally), and the overall observed water structure and dynamics will be dependent on the topological/chemical heterogeneity, and the time-scale of fluctuations in the local curvature (length-scale) of the solvent accessible surface. Moreover, we have

  2. Water activity as the determinant for homogeneous ice nucleation in aqueous solutions

    PubMed

    Koop; Luo; Tsias; Peter

    2000-08-10

    The unique properties of water in the supercooled (metastable) state are not fully understood. In particular, the effects of solutes and mechanical pressure on the kinetics of the liquid-to-solid phase transition of supercooled water and aqueous solutions to ice have remained unresolved. Here we show from experimental data that the homogeneous nucleation of ice from supercooled aqueous solutions is independent of the nature of the solute, but depends only on the water activity of the solution--that is, the ratio between the water vapour pressures of the solution and of pure water under the same conditions. In addition, we show that the presence of solutes and the application of pressure have a very similar effect on ice nucleation. We present a thermodynamic theory for homogeneous ice nucleation, which expresses the nucleation rate coefficient as a function of water activity and pressure. Recent observations from clouds containing ice are in good agreement with our theory and our results should help to overcome one of the main weaknesses of numerical models of the atmosphere, the formulation of cloud processes.

  3. Effects of inland water level oscillation on groundwater dynamics and land-sourced solute transport in subterranean estuary

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Jiao, J. J.; Luo, X.

    2014-12-01

    Inland water level variation widely exists but is usually neglected when conducting research on flow and solute transport in coastal aquifers. A numerical model considering variable-saturation and variable-density based on FEFLOW was used to investigate the influence of inland groundwater level oscillation on groundwater dynamics and land-sourced solute migration in a subterranean estuary over a period of two years. Results show that groundwater level fluctuation induced by water level change at the inland boundary decays linearly seaward but that induced by tidal fluctuation decays exponentially landward. The size of the upper saline plume fluctuates with the inland groundwater level oscillation and the size of the largest USP is more than two times that of the smallest. The largest and the smallest USPs are observed about 25 and 45 days after the lowest and highest inland groundwater level respectively for the parameters and aquifer configuration used in this study. The seawater wedge-freshwater interface shows a rotated movement in response to groundwater level oscillation at inland boundary because its upper part is controlled by the USP movement. Considering that the relatively large horizontal velocity exists in coastal aquifers, a modified Rayleigh number is used to investigate the density-induced unstable phenomenon involving in solute transport in a subterranean estuary. A high Rayleigh number indicates the onset of instability. Fingers and freshwater protuberance are observed in both cases with and without inland groundwater level oscillation. Due to small seaward hydraulic gradient, a high Rayleigh number is reached at the low inland groundwater level, resulting in a long finger plume and high freshwater protuberance morphology. Because of mechanical dispersion induced by the large horizontal velocity when groundwater level is high at the inland boundary, the finger plume and freshwater protuberance well mixes. Consequently, the high concentration plumes

  4. Serial dilution microchip for cytotoxicity test

    NASA Astrophysics Data System (ADS)

    Bang, Hyunwoo; Lim, Sun Hee; Lee, Young Kyung; Chung, Seok; Chung, Chanil; Han, Dong-Chul; Chang, Jun Keun

    2004-08-01

    Today's pharmaceutical industry is facing challenges resulting from the vast increases in sample numbers produced by high-throughput screening (HTS). In addition, the bottlenecks created by increased demand for cytotoxicity testing (required to assess compound safety) are becoming a serious problem. We have developed a polymer PDMS (polydimethylsiloxane) based microfluidic device that can perform a cytotoxicity test in a rapid and reproducible manner. The concept that the device includes is well adjustable to automated robots in huge HTS systems, so we can think of it as a potential dilution and delivery module. Cytotoxicity testing is all about the dilution and dispensing of a drug sample. Previously, we made a PDMS based microfluidic device which automatically and precisely diluted drugs with a buffer solution with serially increasing concentrations. This time, the serially diluted drug solution was directly delivered to 96 well plates for cytotoxicity testing. Cytotoxic paclitaxel solution with 2% RPMI 1640 has been used while carrying out cancerous cell based cytotoxicity tests. We believe that this rapid and robust use of the PDMS microchip will overcome the growing problem in cytotoxicity testing for HTS.

  5. Communication: Modeling of concentration dependent water diffusivity in ionic solutions: Role of intermolecular charge transfer

    SciTech Connect

    Yao, Yi; Berkowitz, Max L. E-mail: ykanai@unc.edu; Kanai, Yosuke E-mail: ykanai@unc.edu

    2015-12-28

    The translational diffusivity of water in solutions of alkali halide salts depends on the identity of ions, exhibiting dramatically different behavior even in solutions of similar salts of NaCl and KCl. The water diffusion coefficient decreases as the salt concentration increases in NaCl. Yet, in KCl solution, it slightly increases and remains above bulk value as salt concentration increases. Previous classical molecular dynamics simulations have failed to describe this important behavior even when polarizable models were used. Here, we show that inclusion of dynamical charge transfer among water molecules produces results in a quantitative agreement with experiments. Our results indicate that the concentration-dependent diffusivity reflects the importance of many-body effects among the water molecules in aqueous ionic solutions. Comparison with quantum mechanical calculations shows that a heterogeneous and extended distribution of charges on water molecules around the ions due to ion-water and also water-water charge transfer plays a very important role in controlling water diffusivity. Explicit inclusion of the charge transfer allows us to model accurately the difference in the concentration-dependent water diffusivity between Na{sup +} and K{sup +} ions in simulations, and it is likely to impact modeling of a wide range of systems for medical and technological applications.

  6. Communication: Modeling of concentration dependent water diffusivity in ionic solutions: Role of intermolecular charge transfer.

    PubMed

    Yao, Yi; Berkowitz, Max L; Kanai, Yosuke

    2015-12-28

    The translational diffusivity of water in solutions of alkali halide salts depends on the identity of ions, exhibiting dramatically different behavior even in solutions of similar salts of NaCl and KCl. The water diffusion coefficient decreases as the salt concentration increases in NaCl. Yet, in KCl solution, it slightly increases and remains above bulk value as salt concentration increases. Previous classical molecular dynamics simulations have failed to describe this important behavior even when polarizable models were used. Here, we show that inclusion of dynamical charge transfer among water molecules produces results in a quantitative agreement with experiments. Our results indicate that the concentration-dependent diffusivity reflects the importance of many-body effects among the water molecules in aqueous ionic solutions. Comparison with quantum mechanical calculations shows that a heterogeneous and extended distribution of charges on water molecules around the ions due to ion-water and also water-water charge transfer plays a very important role in controlling water diffusivity. Explicit inclusion of the charge transfer allows us to model accurately the difference in the concentration-dependent water diffusivity between Na(+) and K(+) ions in simulations, and it is likely to impact modeling of a wide range of systems for medical and technological applications.

  7. Communication: Modeling of concentration dependent water diffusivity in ionic solutions: Role of intermolecular charge transfer

    NASA Astrophysics Data System (ADS)

    Yao, Yi; Berkowitz, Max L.; Kanai, Yosuke

    2015-12-01

    The translational diffusivity of water in solutions of alkali halide salts depends on the identity of ions, exhibiting dramatically different behavior even in solutions of similar salts of NaCl and KCl. The water diffusion coefficient decreases as the salt concentration increases in NaCl. Yet, in KCl solution, it slightly increases and remains above bulk value as salt concentration increases. Previous classical molecular dynamics simulations have failed to describe this important behavior even when polarizable models were used. Here, we show that inclusion of dynamical charge transfer among water molecules produces results in a quantitative agreement with experiments. Our results indicate that the concentration-dependent diffusivity reflects the importance of many-body effects among the water molecules in aqueous ionic solutions. Comparison with quantum mechanical calculations shows that a heterogeneous and extended distribution of charges on water molecules around the ions due to ion-water and also water-water charge transfer plays a very important role in controlling water diffusivity. Explicit inclusion of the charge transfer allows us to model accurately the difference in the concentration-dependent water diffusivity between Na+ and K+ ions in simulations, and it is likely to impact modeling of a wide range of systems for medical and technological applications.

  8. Liquid-phase and vapor-phase dehydration of organic/water solutions

    DOEpatents

    Huang, Yu; Ly, Jennifer; Aldajani, Tiem; Baker, Richard W.

    2011-08-23

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  9. Transient absorption in water-micellar solutions of rhodamine 6G with flash lamp excitation

    SciTech Connect

    Levin, M.B.; Cherkasov, A.S.

    1986-06-01

    This paper studies the kinetics of transient losses in water-micellar solutions of rhodamine 6G by using flash lamp excitation. During the experiments, the laser radiation energy was measured, the time evolution of stimulated emission spectra was recorded; pulse shape was monitored by an oscillograph. The change of generation characteristics of water-micellar solutions of rhodamine 6G as a function of cyclooctatetraene concentration is shown.

  10. Investigation of detection limits for solutes in water measured by laser raman spectrometry

    USGS Publications Warehouse

    Goldberg, M.C.

    1977-01-01

    The influence of experimental parameters on detection sensitivity was determined for laser Raman analysis of dissolved solutes in water. Individual solutions of nitrate, sulfate, carbonate, bicarbonate, monohydrogen phosphate, dihydrogen phosphate, acetate ion, and acetic acid were measured. An equation is derived which expresses the signal-to-noise ratio in terms of solute concentration, measurement time, spectral slit width, laser power fluctuations, and solvent background intensity. Laser beam intensity fluctuations at the sample and solvent background intensity are the most important limiting factors.

  11. Two-Component Self-Diffusion in Solutions: Trehalose and Sucrose in Water

    NASA Astrophysics Data System (ADS)

    Feick, E. J.; von Meerwall, E. D.; Ekdawi, N.; de Pablo, J.

    2001-03-01

    Trehalose is now recognized as a superior substitute for sucrose in solution as a cryoprotectant, for preserving organs destined for transplantation. To explore some aspects of this superiority, we have used the proton NMR pulsed-gradient spin-echo method at T = 30, 50, and 85 deg. C to study the self-diffusion of solvent and solute in aqueous solutions of these molecules as function of their concentration, c. We find that both solute molecules diffuse substantially more slowly than water at the same c and T; that addition of water accelerates solute diffusion more rapidly than that of water; and that while at a given c and T water diffusion is insensitive to solute identity, trehalose diffusion is somewhat slower than sucrose diffusion, an effect which reaches a factor near two at the highest c. The results of our extensive MC and MD molecular simulations of diffusion in sucrose solutions agree quantitatively with our experimental findings at corresponding c. Free-volume theory is also employed to explore the cooperative interactions between solvent and solutes, and to guide the interpretation of both experiment and simulation.

  12. Operations Nougat and Whetstone events: Hard Hat, Danny Boy, Marshmallow, Mudpack, Wishbone, Gumdrop, Diluted Waters, and Tiny Tot, 15 February 1962-17 June 1965. Final report 15 Feb 62-19 Jun 68

    SciTech Connect

    Brady, W.J.; Horton, K.K.; Eubank, B.F.

    1984-01-31

    This report is a personnel oriented history of DOD participation in underground nuclear weapons testing during Operations NOUGAT and WHETSTONE, test events HARD HAT, DANNY BOY, MARSHMALLOW, MUDPACK, WISHBONE, GUMDROP, DILUTED WATERS, and TINY TOT. It is the first in a series of historical reports which will include all DOD underground nuclear weapons tests and DOE underground nuclear weapons tests with significant DOD participation from 1962 forward. In addition to these volumes presenting a history of the underground nuclear test program, a later restricted volume will identify all DOD participants, (military, civilian, and their contractors) and will list their dosimetry data.

  13. Recrystallization of freezable bound water in aqueous solutions of medium concentration

    NASA Astrophysics Data System (ADS)

    Lishan, Zhao; Liqing, Pan; Ailing, Ji; Zexian, Cao; Qiang, Wang

    2016-07-01

    For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings difficulty to application and misleads the interpretation of relevant experiments. Here, we report a quantification scheme for the freezable bound water based on the water-content dependence of glass transition temperature, by which also the concentration range for the solutions that may undergo recrystallization finds a clear definition. Furthermore, we find that depending on the amount of the freezable bound water, different temperature protocols should be devised to achieve a complete recrystallization. Our results may be helpful for understanding the dynamics of supercooled aqueous solutions and for improving their manipulation in various industries. Project supported by the Knowledge Innovation Project of Chinese Academy of Sciences on Water Science Research (Grant No. KJZD-EW-M03) and the National Natural Science Foundation of China (Grant Nos. 11474325 and 11290161).

  14. Influence of surface water/groundwater interactions on stream and wetland water quality: analytical solutions for coupled contaminant transport equations

    NASA Astrophysics Data System (ADS)

    Melek Kazezyilmaz-Alhan, Cevza

    2014-05-01

    Wetlands are located in transitional zones between uplands and downstream flooded systems and surface water/groundwater interactions are frequently observed especially in riparian wetlands where the water level fluctuates frequently during the rainy season. Moreover, surface water/groundwater interactions also influence the characteristics of contaminant transport in pools and riffles, and in meandering type of streams. Therefore, it is important to investigate and solve these processes accurately to improve the prediction of downstream water quality. Although there are many experimental and numerical studies available in the literature which discuss and model the surface water/ground water interactions in streams and wetlands, very few analytical solutions have been conducted. Analytical solutions are helpful tools for verification of numerical solutions and they provide fast and accurate results for practical problems. Furthermore, they provide an understanding to the influence of each parameter in hydrological and contaminant transport models for streams and wetlands. In order to contribute to the research in understanding the behavior of water quality in streams and wetlands, analytical solutions are developed for the coupled contaminant transport equations of several transient storage and wetland models. Among these models are the wetland model WETland Solute TrANsport Dynamics (WETSAND) developed by Kazezyilmaz-Alhan et al. (2007), the transient storage models developed by Bencala and Walters (1983), and Kazezyilmaz-Alhan and Medina (2006). WETSAND is a general comprehensive wetland model, which has both surface flow and solute transport components. In this wetland model, water quality components are solved by advection-dispersion-reaction equations which incorporate surface water/groundwater interactions by including the incoming/outgoing mass due to the groundwater recharge/discharge. The transient storage model developed by Bencala and Walters (1983

  15. Dilute Acid and Autohydrolysis Pretreatment

    NASA Astrophysics Data System (ADS)

    Yang, Bin; Wyman, Charles E.

    Exposure of cellulosic biomass to temperatures of about 120-210°C can remove most of the hemicellulose and produce cellulose-rich solids from which high glucose yields are possible with cellulase enzymes. Furthermore, the use of dilute sulfuric acid in this pretreatment operation can increase recovery of hemicellulose sugars substantially to about 85-95% of the maximum possible versus only about 65% if no acid is employed. The use of small-diameter tubes makes it possible to employ high solids concentrations similar to those preferred for commercial operations, with rapid heat-up, good temperature control, and accurate closure of material balances. Mixed reactors can be employed to pretreat larger amounts of biomass than possible in such small-diameter tubes, but solids concentrations are limited to about 15% or less to provide uniform temperatures. Pretreatment of large amounts of biomass at high solids concentrations is best carried out using direct steam injection and rapid pressure release, but closure of material balances in such “steam gun” devices is more difficult. Although flow of water alone or containing dilute acid is not practical commercially, such flow-through configurations provide valuable insight into biomass deconstruction kinetics not possible in the batch tubes, mixed reactors, or steam gun systems.

  16. Ion-water wires in imidazolium-based ionic liquid/water solutions induce unique trends in density.

    PubMed

    Ghoshdastidar, Debostuti; Senapati, Sanjib

    2016-03-28

    Ionic liquid/water binary mixtures are rapidly gaining popularity as solvents for dissolution of cellulose, nucleobases, and other poorly water-soluble biomolecules. Hence, several studies have focused on measuring the thermophysical properties of these versatile mixtures. Among these, 1-ethyl-3-methylimidazolium ([emim]) cation-based ILs containing different anions exhibit unique density behaviours upon addition of water. While [emim][acetate]/water binary mixtures display an unusual rise in density with the addition of low-to-moderate amounts of water, those containing the [trifluoroacetate] ([Tfa]) anion display a sluggish decrease in density. The density of [emim][tetrafluoroborate] ([emim][BF4])/water mixtures, on the other hand, declines rapidly in close accordance with the experimental reports. Here, we unravel the structural basis underlying this unique density behavior of [emim]-based IL/water mixtures using all-atom molecular dynamics (MD) simulations. The results revealed that the distinct nature of anion-water hydrogen bonded networks in the three systems was a key in modulating the observed unique density behaviour. Vast expanses of uninterrupted anion-water-anion H-bonded stretches, denoted here as anion-water wires, induced significant structuring in [emim][Ac]/water mixtures that resulted in the density rise. Conversely, the presence of intermittent large water clusters disintegrated the anion-water wires in [emim][Tfa]/water and [emim][BF4]/water mixtures to cause a monotonic density decrease. The differential nanostructuring affected the dynamics of the solutions proportionately, with the H-bond making and breaking dynamics found to be greatly retarded in [emim][Ac]/water mixtures, while it exhibited a faster relaxation in the other two binary solutions.

  17. Ion-water wires in imidazolium-based ionic liquid/water solutions induce unique trends in density.

    PubMed

    Ghoshdastidar, Debostuti; Senapati, Sanjib

    2016-03-28

    Ionic liquid/water binary mixtures are rapidly gaining popularity as solvents for dissolution of cellulose, nucleobases, and other poorly water-soluble biomolecules. Hence, several studies have focused on measuring the thermophysical properties of these versatile mixtures. Among these, 1-ethyl-3-methylimidazolium ([emim]) cation-based ILs containing different anions exhibit unique density behaviours upon addition of water. While [emim][acetate]/water binary mixtures display an unusual rise in density with the addition of low-to-moderate amounts of water, those containing the [trifluoroacetate] ([Tfa]) anion display a sluggish decrease in density. The density of [emim][tetrafluoroborate] ([emim][BF4])/water mixtures, on the other hand, declines rapidly in close accordance with the experimental reports. Here, we unravel the structural basis underlying this unique density behavior of [emim]-based IL/water mixtures using all-atom molecular dynamics (MD) simulations. The results revealed that the distinct nature of anion-water hydrogen bonded networks in the three systems was a key in modulating the observed unique density behaviour. Vast expanses of uninterrupted anion-water-anion H-bonded stretches, denoted here as anion-water wires, induced significant structuring in [emim][Ac]/water mixtures that resulted in the density rise. Conversely, the presence of intermittent large water clusters disintegrated the anion-water wires in [emim][Tfa]/water and [emim][BF4]/water mixtures to cause a monotonic density decrease. The differential nanostructuring affected the dynamics of the solutions proportionately, with the H-bond making and breaking dynamics found to be greatly retarded in [emim][Ac]/water mixtures, while it exhibited a faster relaxation in the other two binary solutions. PMID:26911708

  18. Boron sorption from aqueous solution by hydrotalcite and its preliminary application in geothermal water deboronation.

    PubMed

    Guo, Qinghai; Zhang, Yin; Cao, Yaowu; Wang, Yanxin; Yan, Weide

    2013-11-01

    Hydrotalcite and its calcination product were used to treat pure water spiked with various concentrations of boron and geothermal water containing