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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. Nanoassociate formation in highly diluted water solutions of potassium phenosan with and without permalloy shielding.

    PubMed

    Konovalov, Alexander; Ryzhkina, Irina; Maltzeva, Elena; Murtazina, Lyaisan; Kiseleva, Yuliya; Kasparov, Valery; Palmina, Nadezhda

    2015-01-01

    Diluted water solutions of anti-oxidant potassium phenosan, kept before explorations in "usual" conditions and in conditions of "permalloy container", i.e. shielding of solution from the influence of external low-frequency electromagnetic and/or geomagnetic fields, were studied. It is shown that in solutions kept in shielded conditions in the area of high dilution with a concentration of solutions lower than "threshold", nanoobjects called "nanoassociates", are not formed, and anomalous physicochemical and biological properties observed in solutions kept in "usual" conditions, are not found. We conclude that anomalous physicochemical and biological properties of highly diluted water solutions of potassium phenosan made under "usual" conditions are determined by "nanoassociates", in which an external low-frequency electromagnetic and/or geomagnetic field is a necessary condition of the formation.

  3. Concentration of dilute acetone-water solutions using pervaporation

    SciTech Connect

    Hollein, M.E.; Hammond, M.; Slater, C.S. )

    1993-03-01

    The separation of acetone-water mixtures by pervaporation has been studied. Four membranes were evaluated: a silicone composite (SC) membrane, a polydimethylsiloxane (PDMS) membrane, a polymethoxysiloxane (PMS), and a poly-ether-block-polyamide copolymer (PEBA) membrane. The silicone composite membrane exhibited a higher flux and selectivity than any of the other membranes studies. At a feed temperature of 50[degrees]C, a permeate-side pressure of 1 torr, and a feed concentration of 5.0%, the silicone composite membrane had a flux of 1.1 kg/m[sup 2][center dot]h and a selectivity of 50. The effects of temperature and permeate-side pressure on membrane transport were studied using the SC membrane. An increase in temperature increased the flux exponentially, but had little effect on selectivity. An analysis of the data shows that the trend agrees quite well with an Arrhenius-type relationship. As the permeate-side pressure increased, the flux decreased in a sigmoidal fashion over the range evaluated. Selectivity did not change significantly over the lower portion of the pressure range studied. The effect of feed concentration on flux and selectivity was also investigated. 30 refs., 11 figs.

  4. Formulation and make-up of simulate dilute water, low ionic content aqueous solution

    SciTech Connect

    Gdowski, G.

    1997-04-04

    This procedure describes the formulation and make-up of Simulated Dilute Water (SOW), a low-ionic-content water to be used for Activity E-20-50, Long-Term Corrosion Studies. This water has an ionic content which is nominally a factor of ten higher than that of representative waters at or near Yucca Mountain. Representative waters were chosen as J-13 well water [Harrar, 1990] and perched water at Yucca Mountain [Glassley, 1996]. J-13 well water is obtained from ground water that is in contact with the Topopah Spring tuff, which is the repository horizon rock. The perched water is located in the Topopah Spring tuff, but below the repository horizon and above the water table. A nominal times ten higher ionic content was chosen to simulate the effect of ionic concentrating due to elevated temperature water flowing through fractures where salts and minerals have been deposited due to evaporation and boiling.

  5. Dilute and Semidilute Solutions of a Nonionic, Rigid, Water-soluble Polymer

    NASA Astrophysics Data System (ADS)

    Russo, Paul; Huberty, Wayne; Zhang, Donghui; Water-Soluble Rodlike Polymer Team Collaboration

    2014-03-01

    The solution physics of random polymer chains was established largely on the behavior of commercial polymers such as polystyrene for organic solvents or nonionic poly(ethyleneoxide) for aqueous solvents. Not only are these materials widely available for industrial use, they can be synthesized to be essentially monodisperse. When it comes to stiff polymers, good choices are few and less prone to be used in industrial applications. Much was learned from polypeptides such as poly(benzylglutamate) or poly(stearylglutamate) in polar organic solvents and nonpolar organic solvents, respectively, but aqueous systems generally require charge. Poly(Nɛ-2-[2-(2-Methoxyethoxy) ethoxy]acetyl-L-Lysine) a.k.a. PEGL was pioneered by Deming and coworkers. In principle, PEGL provides a convenient platform from which to study stiff polymer behavior--phase relations, dynamics, liquid crystal formation and gelation--all with good molecular weight control and uniformity and without electrical charge. Still, a large gap in knowledge exists between PEGL and traditional rodlike polymer systems. To narrow this gap, dynamic and static scattering, circular dichroism, and viscosity measurements have been made in dilute and semidilute solutions as necessary preliminaries for lyotropic liquid crystalline and gel phases. Supported by NSF DMR 1306262. Department of Chemistry and Macromolecular Studies Group. Current address: Georgia Institute of Technology, School of Materials Science and Engineering.

  6. 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…

  7. 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.

  8. Surface tension of dilute alcohol-aqueous binary fluids: n-Butanol/water, n-Pentanol/water, and n-Hexanol/water solutions

    NASA Astrophysics Data System (ADS)

    Cheng, Kuok Kong; Park, Chanwoo

    2017-01-01

    Surface tension of pure fluids, inherently decreasing with regard to temperature, creates a thermo-capillary-driven (Marangoni) flow moving away from a hot surface. It has been known that few high-carbon alcohol-aqueous solutions exhibit an opposite behavior of the surface tension increasing with regard to temperature, such that the Marangoni flow moves towards the hot surface (self-rewetting effect). We report the surface tensions of three dilute aqueous solutions of n-Butanol, n-Pentanol and n-Hexanol as self-rewetting fluids measured for ranges of alcohol concentration (within solubility limits) and fluid temperatures (25-85 °C). A maximum bubble pressure method using a leak-tight setup was used to measure the surface tension without evaporation losses of volatile components. It was found from this study that the aqueous solutions with higher-carbon alcohols exhibit a weak self-rewetting behavior, such that the surface tensions remain constant or slightly increases above about 60 °C. These results greatly differ from the previously reported results showing a strong self-rewetting behavior, which is attributed to the measurement errors associated with the evaporation losses of test fluids during open-system experiments.

  9. One dimensional model for water and aqueous solutions. Part V. Monte Carlo simulation of dilute solutions of hard rod in waterlike particles

    NASA Astrophysics Data System (ADS)

    Lyubartsev, Alexander; Ben-Naim, Arieh

    2009-11-01

    We have carried out Monte Carlo simulation on the primitive one dimensional model for water described earlier [A. Ben-Naim, J. Chem. Phys. 128, 024506 (2008)]. We show that by taking into account second nearest neighbor interactions, one can obtain the characteristic anomalous solvation thermodynamic quantities of inert solutes in water. This model clearly demonstrates the molecular origin of the large negative entropy of solvation of an inert solute in water.

  10. Dynamic scaling of dilute polymer solutions

    SciTech Connect

    Marqusee, J.A.; Deutch, J.M.

    1981-04-15

    Dynamic scaling relations are presented for the diffusion coefficient and intrinsic viscosity of dilute polymer solutions in D dimensions. The functional integration description of Adler and Freed is used with the correct D-dimensional hydrodynamic interaction and assumptions of power law dependence to obtain the scaling relations. Recursion relations for the exponents are determined in the asymptotic region of large N by an interdimensional scaling argument. 19 references.

  11. Low shear viscosity of dilute polymer solutions

    SciTech Connect

    Chiou, C.S.; Gordon, R.J.

    1980-09-01

    A modification of a viscometer originally proposed by Zimm and Crothers is studied, which may be used to measure ultra low shear viscosity for highly dilute polymer solutions. This may provide useful information on polymer coil dimensions and relaxation time. Use of the low shear viscosity data leads to large value of relaxation time induced by polymer addition to a concentration of only 2 to 3 ppM by wt. This finding is consistent with the marked viscoelastic effects exhibited by these solutions.

  12. Activity Coefficients at Infinite Dilution and Physicochemical Properties for Organic Solutes and Water in the Ionic Liquid 1-Ethyl-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate.

    PubMed

    Wlazło, Michał; Marciniak, Andrzej; Letcher, Trevor M

    New data of activity coefficients at infinite dilution, γ13(∞), for 65 different solutes including alkanes, alkenes, alkynes, cycloalkanes, aromatic hydrocarbons, alcohols, thiophene, ethers, ketones, aldehydes, esters and water in the ionic liquid 1-ethyl-3-methylimidazolium trifluorotris(perfluoroethyl)phosphate, were determined using inverse gas chromatography within the temperature range from 318.15 to 368.15 K. This is a continuation of our study of ionic liquids based on this anion. The results are compared with the other trifluorotris(perfluoroethyl)phosphate ionic liquids. The γ13(∞) values were used to calculate thermodynamic functions such as partial molar excess Gibbs energies [Formula: see text], enthalpies [Formula: see text] and entropies [Formula: see text] as well as gas-liquid partition coefficients of the solutes, KL. These values were used to determine the linear free energy relationship (LFER) system constants as a function of temperature. The selectivities at infinite dilution needed for some extraction problems were calculated and compared with literature data of ionic liquids based on the trifluorotris(perfluoroethyl)phosphate anion and the 1-ethyl-3-methylimidazolium cation. Additionally, the density and viscosity of the investigated ionic liquid at temperatures from 298.15 to 348.15 K were measured.

  13. 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.

  14. 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.

  15. Monte Carlo Simulation of Aqueous Dilute Solutions of Polyhydric Alcohols

    NASA Astrophysics Data System (ADS)

    Lilly, Arnys Clifton, Jr.

    In order to investigate the details of hydrogen bonding and solution molecular conformation of complex alcohols in water, isobaric-isothermal Monte Carlo simulations were carried out on several systems. The solutes investigated were ethanol, ethylene glycol, 1,2-propylene glycol, 1,3 -propylene glycol and glycerol. In addition, propane, which does not hydrogen bond but does form water hydrates, was simulated in aqueous solution. The complex alcohol-water systems are very nonideal in their behavior as a function of solute concentration down to very dilute solutions. The water model employed was TIP4P water^1 and the intermolecular potentials employed are of the Jorgensen type^2 in which the interactions between the molecules are represented by interaction sites usually located on nuclei. The interactions are represented by a sum of Coulomb and Lennard-Jones terms between all intermolecular pairs of sites. Intramolecular rotations in the solute are modeled by torsional potential energy functions taken from ethanol, 1-propanol and 2-propanol for C-O and C-C bond rotations. Quasi-component pair correlation functions were used to analyze the hydrogen bonding. Hydrogen bonds were classified as proton acceptor and proton donor bonds by analyzing the nearest neighbor pair correlation function between hydroxyl oxygen and hydrogen and between solvent-water hydrogen and oxygen. The results obtained for partial molar heats of solution are more negative than experimental values by 3.0 to 14 kcal/mol. In solution, all solutes reached a contracted molecular geometry with the OH groups generally on one side of the molecule. There is a tendency for the solute OH groups to hydrogen bond with water, with more proton acceptor bonds than proton donor bonds. The water -solute binding energies correlate with experimental measurements of the water-binding properties of the solute. ftn ^1Jorgensen, W. L. et al, J. Chem. Phys., 79, 926 (1983). ^2Jorgensen, W. L., J. Phys Chem., 87, 5304

  16. Unexpected inhibition of CO2 gas hydrate formation in dilute TBAB solutions and the critical role of interfacial water structure

    SciTech Connect

    Nguyen, Ngoc N.; Nguyen, Anh V.; Nguyen, Khoi T.; Rintoul, Llew; Dang, Liem X.

    2016-12-01

    Gas hydrates formed under moderated conditions open up novel approaches to tackling issues related to energy supply, gas separation, and CO2 sequestration. Several additives like tetra-n-butylammonium bromide (TBAB) have been empirically developed and used to promote gas hydrate formation. Here we report unexpected experimental results which show that TBAB inhibits CO2 gas hydrate formation when used at minuscule concentration. We also used spectroscopic techniques and molecular dynamics simulation to gain further insights and explain the experimental results. They have revealed the critical role of water alignment at the gas-water interface induced by surface adsorption of tetra-n-butylammonium cation (TBA+) which gives rise to the unexpected inhibition of dilute TBAB solution. The water perturbation by TBA+ in the bulk is attributed to the promotion effect of high TBAB concentration on gas hydrate formation. We explain our finding using the concept of activation energy of gas hydrate formation. Our results provide a step toward to mastering the control of gas hydrate formation.

  17. Random bilayer phases of dilute surfactant solutions

    NASA Astrophysics Data System (ADS)

    Cates, M. E.; Roux, D.

    1990-12-01

    Surfactant molecules in dilute solution may aggregate reversibly into extended structures. For suitably chosen molecules, the preferred packing involves a locally flat bilayer which tends to wander entropically at large distances. At low temperatures (and/or high concentrations) the system forms a stack of flat sheets with one-dimensional quasi-long range order (a smectic liquid crystal), but at high temperatures or low concentrations, the stack can melt into a random surface structure that resembles a multiply connected labyrinth or 'sponge' of bilayer in a sea of solvent. Recent theoretical and experimental progress in understanding the properties of the sponge is reviewed. The authors argue that the sponge phase may provide a good system for the study of various liquid-state critical phenomena.

  18. 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

  19. Communication: Stiffening of dilute alcohol and alkane mixtures with water

    NASA Astrophysics Data System (ADS)

    Ashbaugh, Henry S.; Wesley Barnett, J.; Saltzman, Alexander; Langrehr, Mae E.; Houser, Hayden

    2016-11-01

    We probe the anomalous compressibilities of dilute mixtures of alcohols and alkane gases in water using molecular simulations. The response to increasing solute concentration depends sensitively on temperature, with the compressibility decreasing upon solute addition at low temperatures and increasing at elevated temperatures. The thermodynamic origin of stiffening is directly tied to the solute's partial compressibility, which is negative at low temperatures and rises above water's compressibility with increasing temperature. Hydration shell waters concurrently tilt towards clathrate-like structures at low temperatures that fade with heating. Kirkwood-Buff theory traces the solute's partial compressibility to changes in the solute-water association volume upon heating and incongruous packing of waters at the boundary between the more structured hydration shell and bulk water.

  20. Fate of phosphorus in diluted urine with tap water.

    PubMed

    Liu, Xiaoning; Wen, Guoqi; Wang, Huihui; Zhu, Xiaoqi; Hu, Zhengyi

    2014-10-01

    P loss during the fresh urine storage process is inevitable because of the presence of Ca and Mg. Dilution is one of the most important parameters influencing urine composition and subsequent P recovery. This study aimed to investigate the fate of P in urine with different dilution ratios (Vwater/Vurine, i.e., 0/100, 25/75, 50/50 and 75/25). The results indicate that the percentage of P loss increased from 43% to 76% as the dilution ratio increased from 0/100 to 75/25 because of more Ca and Mg obtained from tap water. Meanwhile, P removal efficiency through struvite precipitation decreased from 51% to 8% because of lower supersaturation ratio as a result of dilution. Struvite crystals with high purity were still obtained even under a dilution ratio of 50/50 urine solution. Batch experiments were also performed to study the influence of temperature (15-35°C) on P recovery and crystal size. For different dilution ratios of urine solutions, no significant discrepancy for the P removal efficiencies were observed at 15 and 35°C, whereas the P removal efficiencies at 25°C showed an increasing gap with those at 15 and 35°C. The largest average crystal sizes were found at 25°C, which was opposite to the trend of P removal efficiency.

  1. Reactions of gaseous, elemental mercury with dilute halogen solutions

    SciTech Connect

    Mendelsohn, M.H.; Livengood, C.D.

    1996-07-01

    Of the trace elements known to exist in fossil fuels, mercury (Hg) has emerged as one of the greatest concerns. Mercury has been found to be emitted from combustion in at least two different chemical forms: elemental Hg and oxidized Hg compounds. Precise identification of the oxidized compounds emitted has not been accomplished to date. However, most workers in this field assume that mercuric chloride should be the predominant oxidized species. Mercuric chloride should be readily removed in a wet scrubber system because of its relatively high solubility in water. However, it has been presumed, and we have shown, that elemental Hg will pass through a wet scrubber system with little or no removal being effected. Therefore, it is important, in order to obtain a high total Hg removal, to study methods that might result in a removal of gaseous, elemental Hg from a flue-gas stream. In this regard, we have been studying the effect of dilute halogen-containing solutions on elemental Hg in gas streams of various compositions. In particular, the results of passing Hg through bubblers containing solutions of iodine, chlorine, and chloric acid are described. Mercury found in the bubbler solutions is an indication of the extent of reaction (oxidation) of elemental Hg with the halogen species, since we have found very little Hg transferred to the liquid phase when only distilled water is used in the bubblers. Results using commercial iodine, sodium hypochlorite, and NOXSORB (sup TM) solutions are presented and discussed.

  2. [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.

  3. 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.

  4. 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

    2013-11-07

    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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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%.

  10. Effect of diamagnetic contribution of water on harmonics distribution in a dilute solution of iron oxide nanoparticles measured using high-Tc SQUID magnetometer

    NASA Astrophysics Data System (ADS)

    Saari, Mohd Mawardi; Tsukamoto, Yuya; Kusaka, Toki; Ishihara, Yuichi; Sakai, Kenji; Kiwa, Toshihiko; Tsukada, Keiji

    2015-11-01

    The magnetization curve of iron oxide nanoparticles in low-concentration solutions was investigated by a highly sensitive high-Tc superconducting quantum interference device (SQUID) magnetometer. The diamagnetic contribution of water that was used as the carrier liquid was observed in the measured magnetization curves in the high magnetic field region over 100 mT. The effect of the diamagnetic contribution of water on the generation of harmonics during the application of AC and DC magnetic fields was simulated on the basis of measured magnetization curves. Although the diamagnetic effect depends on concentration, a linear relation was observed between the detected harmonics and concentration in the simulated and measured results. The simulation results suggested that improvement could be expected in harmonics generation because of the diamagnetic effect when the iron concentration was lower than 72 μg/ml. The use of second harmonics with an appropriate bias of the DC magnetic field could be utilized for realization of a fast and highly sensitive detection of magnetic nanoparticles in a low-concentration solution.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Wu, Henry; Mayeshiba, Tam; Morgan, Dane

    2016-07-01

    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.

  13. The cluster structure of dilute aqueous-alcoholic solutions and molecular light scattering in them

    NASA Astrophysics Data System (ADS)

    Malomuzh, N. P.; Slinchak, E. L.

    2007-11-01

    The structures, equations of state, and character of fluctuations of dilute water-glycerol solutions are discussed. Two or three glycerol and about ten water molecules were found to form a fairly stable molecular complex. We call this complex elementary cluster (pseudoparticle). In a certain region of state parameters, the system could be considered a solution of pseudoparticles (clusters). Its properties were modeled by the van der Waals equation. The character of interactions between clusters was analyzed. An anomalous increase in concentration and molecular light scattering fluctuations was caused by the approach to the solution “pseudospinodal.” The experimental data were found to be in quite satisfactory agreement with theoretical estimates.

  14. 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.

  15. Room-Temperature Tensile Behavior of Oriented Tungsten Single Crystals with Rhenium in Dilute Solid Solution

    DTIC Science & Technology

    1966-01-01

    SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION Sby M. Garfinkle Lewis Research Center Cleveland, Ohio 20060516196 NATIONAL AERONAUTICS AND...WITH RHENIUM IN DILUTE SOLID SOLUTION By M. Garfinkle Lewis Research Center Cleveland, Ohio NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by...ORIENTED TUNGSTEN SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION * by M. Garfinkle Lewis Research Center SUMMARY Tungsten single crystals

  16. 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.

  17. Reverse osmosis separation of radium from dilute aqueous solutions

    SciTech Connect

    Subramanian, K.S.; Sastri, V.S.

    1980-03-01

    Porous cellulose acetate membranes obtained from Osmonics Inc. were characterized in terms of pure water permeability constant, solute transport parameter, and mass transfer coefficient with aqueous sodium chloride solution as the reference system. Reverse osmosis separation behavior of radium-226 as nitrate, chloride, and sulfate salts was studied. Reverse osmosis method of removing radium-226 from aqueous solutions has been compared with other methods, and it has been shown to be one of the best methods for alleviating radium contamination problems.

  18. The study on pervaporation behaviors of dilute organic solution through PDMS/PTFE composite membrane.

    PubMed

    Zhang, Wei-dong; Sun, Wei; Yang, Jing; Ren, Zhong-qi

    2010-01-01

    As an energy-efficient alternative to distillation, pervaporation has been widely combined with fermentation to remove organic compounds from their dilute solutions in a fermentation broth. In this work, the organic permselective composite membrane is prepared by coating polydimethylsiloxane (PDMS) cross-linked with n-heptane on the substrate of polytetrafluoroethylene(PTFE) membrane. The separation behavior is studied in different dilute organic solutions, which include acetone dilute solution, butanone dilute solution, cyclohexanone dilute solution, ethanol dilute solution, isopropanol dilute solution, n-butyl alcohol dilute solution, acetic acid dilute solution, and ethyl acetate dilute solution. Most of these solutions are main reaction products or by-products from fermentation process. The effects of solubility of organics in the membrane, molecular weight, and polarity of the organics on the pervaporation performance are investigated. The effects of operating temperature and organic concentration in the feed solutions on the performance of composite membrane are studied as well. The experimental results show that molecular volume has less influence than solubility and molecular polarity for these organic solvent. The selectivity of PDMS membrane to ethyl acetate is relative high due to good solubility and diffusion of ethyl acetate molecules in polymer.

  19. THE ROLE OF ELECTRON CONFIGURATION ON PROPERTIES IN DILUTE SOLID SOLUTION ALLOYS

    DTIC Science & Technology

    THE ROLE OF ELECTRON CONFIGURATION ON THE PROPERTIES OF DILUTE SOLID SOLUTION ALLOYS IS DISCUSSED IN TERMS OF THE EFFECT OF DILUTE IMPURITIES ON THE RECRYSTALLIZATION CHARACTERISTICS OF PURE METALLIC ELEMENTS.

  20. Activity coefficients of chlorophenols in water at infinite dilution

    SciTech Connect

    Tabai, S.; Rogalski, M.; Solimando, R.; Malanowski, S.K.

    1997-11-01

    The total pressure of aqueous solutions of chlorophenols was determined by a ebulliometric total pressure method for the aqueous solutions of phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol in the temperature range from 40 to 90 C. The activity coefficients at infinite dilution and the Henry constants were derived.

  1. 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.

  2. Volatile release from aqueous solutions under dynamic headspace dilution conditions.

    PubMed

    Marin, M; Baek, I; Taylor, A J

    1999-11-01

    Static equilibrium was established between the gas phase (headspace) and an unstirred aqueous phase in a sealed vessel. The headspace was then diluted with air to mimic the situation when a container of food is opened and the volatiles are diluted by the surrounding air. Because this first volatile signal can influence overall flavor perception, the parameters controlling volatile release under these conditions are of interest. A mechanistic model was developed and validated experimentally. Release of compounds depended on the air-water partition coefficient (K(aw)) and the mass transport in both phases. For compounds with K(aw) values <10(-)(3), K(aw) was the factor determining release rate. When K(aw) was >10(-)(3), mass transport in the gas phase became significant and the Reynolds number played a role. Because release from packaged foods occurs at low Reynolds numbers, whereas most experiments are conducted at medium to high Reynolds numbers, the experimentally defined profile may not reflect the real situation.

  3. 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'.

  4. Effect of ethanol, temperature, and gas flow rate on volatile release from aqueous solutions under dynamic headspace dilution conditions.

    PubMed

    Tsachaki, Maroussa; Gady, Anne-Laure; Kalopesas, Michalis; Linforth, Robert S T; Athès, Violaine; Marin, Michele; Taylor, Andrew J

    2008-07-09

    On the basis of a mechanistic model, the overall and liquid mass transfer coefficients of aroma compounds were estimated during aroma release when an inert gas diluted the static headspace over simple ethanol/water solutions (ethanol concentration = 120 mL x L(-1)). Studied for a range of 17 compounds, they were both increased in the ethanol/water solution compared to the water solution, showing a better mass transfer due to the presence of ethanol, additively to partition coefficient variation. Thermal imaging results showed differences in convection of the two systems (water and ethanol/water) arguing for ethanol convection enhancement inside the liquid. The effect of ethanol in the solution on mass transfer coefficients at different temperatures was minor. On the contrary, at different headspace dilution rates, the effect of ethanol in the solution helped to maintain the volatile headspace concentration close to equilibrium concentration, when the headspace was replenished 1-3 times per minute.

  5. 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.

  6. Dilute-solution Structure of Charged Arborescent Graft Polymer

    SciTech Connect

    Yun, Seok; Briber, R M; Kee, R. Andrew; Gauthier, Mario

    2006-01-01

    The solutions of charged G1 arborescent polystyrene-graft-poly(2-vinylpyridine) copolymers in methanol-d4 and D{sub 2}O were investigated over a dilute concentration range {phi} = 0.005-0.05 ({phi}: mass fraction) using small-angle neutron scattering (SANS). Upon addition of acid (HCl) arborescent graft polymers became charged and a peak appeared in SANS data. The interparticle distance (d{sub exp}) calculated from a peak position corresponded to the expected value (d{sub uni}) for a uniform particle distribution. This indicates the formation of liquid-like ordering due to long-range Coulombic repulsions. The smaller dielectric constant of methanol-d4 resulted in long-range electrostatic repulsions persisting to lower polymer concentration than in D{sub 2}O. The slow mode scattering was observed by dynamic light scattering measurements for the same polymer solutions, indicating the presence of structural inhomogeneity in the solutions. Both the peak and slow mode disappeared by addition of NaCl or excess HCl into the solutions due to the screening of electrostatic interactions. The G1 polymer grafted with longer P2VP chains (M{sub w} {approx} 30,000 versus 5000 g mol) formed a gel on addition of HCl. This result reveals that molecular expansion is more significant for arborescent polymers with longer (M{sub w} {approx} 30,000) linear polyelectrolyte branches, resulting in gelation for {phi} > 0.01. Upon addition of NaCl or excess HCl a gel transformed back to a liquid resulted from the screening of electrostatic interactions.

  7. Conductivity and electrophoretic mobility of dilute ionic solutions.

    PubMed

    Allison, Stuart; Wu, Hengfu; Twahir, Umar; Pei, Hongxia

    2010-12-01

    Two complementary continuum theories of electrokinetic transport are examined with particular emphasis on the equivalent conductance of binary electrolytes. The "small ion" model [R.M. Fuoss, L. Onsager, J. Phys. Chem. 61 (1957) 668] and "large ion" model [R.W. O'Brien, L.R. White, J. Chem. Soc. Faraday Trans. 2 (74) (1978) 1607] are both discussed and the "large ion" model is generalized to include an ion exclusion distance and to account in a simple but approximate way for the Brownian motion of all ions present. In addition, the "large ion" model is modified to treat "slip" hydrodynamic boundary conditions in addition to the standard "stick" boundary condition. Both models are applied to the equivalent conductance of dilute KCl, MgCl(2), and LaCl(3) solutions and both are able to reproduce experimental conductances to within an accuracy of several tenths of a percent. Despite fundamental differences in the "small ion" and "large ion" theories, they both work equally well in this application. In addition, both "stick-large ion" and "slip-large ion" models are equally capable of accounting for the equivalent conductances of the three electrolyte solutions.

  8. Nonequilibrium thermodynamics of dilute polymer solutions in flow.

    PubMed

    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.

  9. 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.

  10. 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.

  11. 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.

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

    DOE PAGES

    Wijesinghe, Sidath; Maskey, Sabina; Perahia, Dvora; ...

    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

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

    USGS Publications Warehouse

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

    1988-01-01

    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.

  14. 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.

  15. Dilution

    PubMed Central

    Lavie, Nilli; Torralbo, Ana

    2010-01-01

    Load theory of attention proposes that distractor processing is reduced in tasks with high perceptual load that exhaust attentional capacity within task-relevant processing. In contrast, tasks of low perceptual load leave spare capacity that spills over, resulting in the perception of task-irrelevant, potentially distracting stimuli. Tsal and Benoni (2010) find that distractor response competition effects can be reduced under conditions with a high search set size but low perceptual load (due to a singleton color target). They claim that the usual effect of search set size on distractor processing is not due to attentional load but instead attribute this to lower level visual interference. Here, we propose an account for their findings within load theory. We argue that in tasks of low perceptual load but high set size, an irrelevant distractor competes with the search nontargets for remaining capacity. Thus, distractor processing is reduced under conditions in which the search nontargets receive the spillover of capacity instead of the irrelevant distractor. We report a new experiment testing this prediction. Our new results demonstrate that, when peripheral distractor processing is reduced, it is the search nontargets nearest to the target that are perceived instead. Our findings provide new evidence for the spare capacity spillover hypothesis made by load theory and rule out accounts in terms of lower level visual interference (or mere “dilution”) for cases of reduced distractor processing under low load in displays of high set size. We also discuss additional evidence that discounts the viability of Tsal and Benoni's dilution account as an alternative to perceptual load. PMID:21133554

  16. 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.

  17. 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.

  18. 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.

  19. Photochemical dehydrogenation of ethanol in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Handman, J.; Harriman, A.; Porter, G.

    1984-02-01

    The cyclic photodissociation of water has not yet been achieved in a homogeneous solution using visible light. The replacement of the sacrificial electron donor with such waste materials as sulfide is suggested as a method for improving homogeneous systems. Attention is given to the efficient photogeneration of H2 by means of a system that employs a low grade fermentation product, aqueous ethanol, as electron donor. The photoproduction of H2 is coupled to the oxidation of the ethanol by means of NADH/alcohol dehydrogenase as a relay.

  20. VOC destruction by water diluted hydrogen mild combustion.

    PubMed

    Sabia, P; Romeo, F; de Joannon, M; Cavaliere, A

    2007-06-01

    This study represents a preliminary numerical evaluation of the effect of steam dilution and hydrogen addition on the oxidation of formaldehyde and benzene, chosen as representative of the volatile organic compounds (VOC), in mild condition by evaluating the autoignition time and the steady state attainment. These parameters are important in the design of thermal VOC destruction plants since they influence the abatement efficiency and, therefore, the plant dimension. It has come out that, in comparison with the system diluted in nitrogen, steam induces lower autoignition times and, on the other hand, longer times for the attainment of the steady state. In contrast, for very high water content the autoignition time slightly increases. In particular results have shown that is possible to identify an optimum value of steam content that allows for the attainment of the steady state condition by the lowest residence time. Hydrogen addition to systems diluted in nitrogen promotes the oxidation reactions and anticipates the steady state condition. In steam diluted systems hydrogen delays the autoignition of the mixtures even though anticipates the attainment of the complete destruction of the VOC. The rate of production analysis has showed that the H(2)/O(2) reactions, that promote the ignition and the destruction of VOC, are sensibly modified by the presence of water and hydrogen.

  1. 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

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

    DOE PAGES

    Chaudhari, Mangesh I.; Sabo, Dubravko; Pratt, Lawrence R.; ...

    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

  3. 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.

  4. 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.

  5. Kinetics of phase separation and coarsening in dilute surfactant pentaethylene glycol monododecyl ether solutions.

    PubMed

    Tanaka, S; Kubo, Y; Yokoyama, Y; Toda, A; Taguchi, K; Kajioka, H

    2011-12-21

    We investigated the phase separation phenomena in dilute surfactant pentaethylene glycol monodedecyl ether (C(12)E(5)) solutions focusing on the growth law of separated domains. The solutions confined between two glass plates were found to exhibit the phase inversion, characteristic of the viscoelastic phase separation; the majority phase (water-rich phase) nucleated as droplets and the minority phase (micelle-rich phase) formed a network temporarily, then they collapsed into an usual sea-island pattern where minority phase formed islands. We found from the real-space microscopic imaging that the dynamic scaling hypothesis did not hold throughout the coarsening process. The power law growth of the domains with the exponent close to 1/3 was observed even though the coarsening was induced mainly by hydrodynamic flow, which was explained by Darcy's law of laminar flow.

  6. 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).

  7. 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.

  8. Acoustic and volumetric studies of intermolecular interactions in dilute solutions of methanol in aromatic amines

    NASA Astrophysics Data System (ADS)

    Marczak, W.; Chowanska, A.; Piwowarska, B.

    2005-10-01

    Limiting partial compressibilities and volumes of methanol in pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine and 2,6-dimethylpyridine were calculated from the experimental speeds of sounds and densities of dilute solutions at 298.15 K. The limiting functions were found to be linearly correlated with the association energies of isolated 1:1 complexes of the pyridine derivatives with water. Those association energies are close to the energies for similar complexes with methanol. The results evidence that ortho effect enhances the ability of pyridines to hydrogen bonding with methanol in the same way as with water. The effect consist in changes of hydrogen bond energy, unspecific interactions with a steric hindrance, e.g. between hydrocarbon tail of the alcohol molecule and the methyl group in the ring, and changes in resonance interactions. Stronger hydrogen bonds cause smaller partial molar compressibilities and volumes of the solute, as well as greater negative enthalpies of solution. Importantly, single molecule of water or methanol forms one hydrogen bond with the proton-accepting solvent.

  9. 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.

  10. 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.

  11. A single bubble path transition from spiral to zigzag in dilute surfactant solution

    NASA Astrophysics Data System (ADS)

    Tagawa, Yoshiyuki; Kawaguchi, Wataru; Funakubo, Ami; Takagi, Shu; Matsumoto, Yoichiro

    2007-11-01

    The surfactant effect on a single bubble motion is so important that it changes whole bubbly flow structures. One of the surfactant key effects is to decrease bubble rise velocity. This phenomenon is described as Marangoni effect which is quantitatively investigated by many experiments and numerical calculations of straight rising bubbles. Some other previous researches studied a bubble trajectory transition from a zigzag trajectory to spiral in super purified water (Mougin et al. 2002). However, the surfactant effect on this 3D motion bubbles is not enough investigated. To investigate it in detail, we measured trajectories of single bubbles rising in a tank of 1300mm height filled with dilute surfactant solution. We observed a bubble motion transition from spiral to zigzag, which is just reverse transition of trajectories in super purified water. Considering our other measurement results of bubble trajectories in super purified water, those in different surfactant solution, and a profile of bubble rise velocity, we think this interesting result is explained by surfactant concentration on a bubble surface. We will discuss its mechanism in detail in our presentation.

  12. Selective monovalent cation association and exchange around Keplerate polyoxometalate macroanions in dilute aqueous solutions.

    PubMed

    Pigga, Joseph M; Teprovich, Joseph A; Flowers, Robert A; Antonio, Mark R; Liu, Tianbo

    2010-06-15

    The interaction between water-soluble Keplerate polyoxometalate {Mo(72)Fe(30)} macroions and small countercations is explored by laser light scattering, anomalous small-angle X-ray scattering (ASAXS), and isothermal titration calorimetry (ITC) techniques. The macroions are found to be able to select the type of associated counterions based upon the counterions' valence state and hydrated size, when multiple types of additional cations are present in solution (even among different monovalent cations). The preference goes to the cations with higher valences or smaller hydrated sizes if the valences are identical. This counterion exchange process changes the magnitude of the macroion-counterion interaction and, thus, is reflected in the dimension of the self-assembled {Mo(72)Fe(30)} blackberry supramolecular structures. The hydrophilic macroions exhibit a competitive recognition of various monovalent counterions in dilute solutions. A critical salt concentration (CSC) for each type of cation exists for the blackberry formation of {Mo(72)Fe(30)} macroions, above which the blackberry size increases significantly with the increasing total ionic strength in solution. The CSC values are much smaller for cations with higher valences and also decrease with the cations' hydrated size for various monovalent cations. The change of blackberry size corresponding to the change of ionic strength in solution is reversible.

  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. Solute dilution at the Borden and Cape Cod groundwater tracer tests

    USGS Publications Warehouse

    Thierrin, Joseph; Kitanidis, Peter K.

    1994-01-01

    This study presents an analysis of the rate of dilution of a conservative nonreactive tracer in two well-known field experiments: The Borden (Ontario, Canada) experiment and the Cape Cod (Massachusetts) experiment. In evaluating the dilution of injected sodium bromide, in addition to computing the second spatial moments, we have used the dilution index and the reactor ratio. The dilution index is a measure of the formation volume occupied by the solute plume, and the reactor ratio is a shape factor, which measures how stretched and deformed the plume is. Unlike the second moments, which may go up or down during an experiment, the dilution index should increase monotonically. The results for both plumes were quite similar. After an initial period the dilution index increased linearly with time, which is macroscopically equivalent to transport in two-dimensional uniform flow. The reactor ratio was relatively constant during the period of the experiments. Their values, about 0.72 for the Borden test and 0.63 for the Cape Cod test, indicate that the Cape Cod plume was more stretched and deformed than the Borden plume. The maximum concentration, which is an alternative to the dilution index for quantifying dilution, was found to be more erratic and more susceptible to sampling error.

  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. The grand partition function of dilute biregular solutions

    NASA Astrophysics Data System (ADS)

    Nagamori, Meguru; Ito, Kimihisa; Tokuda, Motonori

    1994-10-01

    It has been demonstrated that the grand partition function (GPF) of biregular solutions contains in one single equation such thermodynamic principles as Henry's law, Raoult's law, the Gibbs-Duhem relation, Raoultian activity coefficients and their finite power series, Wagner's rec-iprocity, Schenck-Frohberg-Steinmetz's interchange, Lupis-Elliott's additivity, Mori-Morooka's disparity, and Darken's quadratic formalism. The logarithm of the Raoultian activity coefficient of species i, In γi should not be expressed by the Taylor series expansion, lest its truncation infringe the Gibbs-Duhem equation. The GPF methodology establishes that In γi, is not a vector but a scalar point function, free from any path dependence. While Darken's quadratic formalism employs three parameters to describe a ternary solution, the present biregularity approximation offers an alternative using seven empirical parameters, in case better accuracy is needed.

  17. Adsorption of organic acids from dilute aqueous solution onto activated carbon

    SciTech Connect

    Wang, S.W.

    1980-06-01

    The radioisotope technique was used to study the removal of organic acid contaminants from dilute aqueous solutions onto activated carbon. Acetic acid, propionic acid, n-butyric acid, n-hexanoic acid and n-heptanoic acid were studied at 278, 298, and 313/sup 0/K. Three bi-solute acid mixtures (acetic and propionic acids, acetic and butanoic acids, and propionic and butanoic acids) were studied at 278 and 298/sup 0/K. Isotherms of the single-solute systems were obtained at three different temperatures in the very dilute concentration region (less than 1% by weight). These data are very important in the prediction of bi-solute equilibrium data. A Polanyi-based competitive adsorption potential theory was used to predict the bi-solute equilibrium uptakes. Average errors between calculated and experimental data ranges from 4% to 14%. It was found that the competitive adsorption potential theory gives slightly better results than the ideal adsorbed solution theory.

  18. 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.

  19. Segregation of solutes and gases in experimental freezing of dilute solutions: implications for natural glacial systems

    NASA Astrophysics Data System (ADS)

    Killawee, J. A.; Fairchild, I. J.; Tison, J.-L.; Janssens, L.; Lorrain, R.

    1998-12-01

    Low ionic strength waters containing significant calcium and bicarbonate are common in nature, but little literature exists on their behaviour during freezing. Modelling indicates that freezing-induced concentration of solutes (in a closed-system) would lead to progressive increase in calcite saturation index, despite rising partial pressure of CO 2 (PCO 2), but the consequences of CaCO 3 precipitation for the distribution of matter between solid, liquid, and gas phases required experimental investigation. We studied the effects of variations in the rate of advance of an ice-water interface and in the initial degree of saturation for calcite on the behaviour of the system. Downward growth of ice in a 24-cm diameter cylindrical vessel was achieved at a constant linear rate of 3 or 8 mm/h by the progressive cooling of an overlying alcohol reservoir, and the expansion of volume accommodated by regular water sampling through side ports, together with a small expansion chamber. Initial air-saturated solutions (initial PCO 2 in the range 10 -3 to 10 -3.2) were prepared to reflect a range from strongly undersaturated to supersaturated for calcite. Comparative blank experiments were run using deionized water. Ice growth led to enrichment in solutes at the ice-water interface and the creation of a diffusive boundary layer, calculated to be 0.6 mm thick, truncated below by convecting fluid. The first-formed ice (stage 1), was relatively solute-rich because of initial rapid ice nucleation. Where solutions were not strongly supersaturated for calcite this was followed by formation of a solute-poor (stage 2) ice. Ice-interface water segregation coefficients of stage 2 ice were calculated to be 0.0004-0.003 for various solute ions. The relative magnitude of segregation coefficients (Mg 2+ > Ca 2+ > Sr 2+) is attributed to interstitial incorporation (coupled with HCO 3-) in the ice lattice, and controlled by ion size. Air bubbles nucleated once nitrogen supersaturation had

  20. Dynamics of single semiflexible polymers in dilute solution

    NASA Astrophysics Data System (ADS)

    Nikoubashman, Arash; Milchev, Andrey; Binder, Kurt

    2016-12-01

    We study the dynamics of a single semiflexible chain in solution using computer simulations, where we systematically investigate the effect of excluded volume, chain stiffness, and hydrodynamic interactions. We achieve excellent agreement with previous theoretical considerations, but find that the crossover from the time τb, up to which free ballistic motion of the monomers describes the chain dynamics, to the times W-1 or τ0, where anomalous monomer diffusion described by Rouse-type and Zimm-type models sets in, requires two decades of time. While in the limit of fully flexible chains the visibility of the anomalous diffusion behavior is thus rather restricted, the t3/4 power law predicted for stiff chains without hydrodynamic interactions is verified. Including hydrodynamics, evidence for the predicted [tln (t ) ] 3 /4 behavior is obtained. Similar good agreement with previous theoretical predictions is found for the decay of the bond autocorrelation functions and the end-to-end vector correlation. Finally, several predictions on the variation of characteristic relaxation times with persistence length describing the chain stiffness are tested.

  1. Can tritiated water-dilution space accurately predict total body water in chukar partridges

    SciTech Connect

    Crum, B.G.; Williams, J.B.; Nagy, K.A.

    1985-11-01

    Total body water (TBW) volumes determined from the dilution space of injected tritiated water have consistently overestimated actual water volumes (determined by desiccation to constant mass) in reptiles and mammals, but results for birds are controversial. We investigated potential errors in both the dilution method and the desiccation method in an attempt to resolve this controversy. Tritiated water dilution yielded an accurate measurement of water mass in vitro. However, in vivo, this method yielded a 4.6% overestimate of the amount of water (3.1% of live body mass) in chukar partridges, apparently largely because of loss of tritium from body water to sites of dissociable hydrogens on body solids. An additional source of overestimation (approximately 2% of body mass) was loss of tritium to the solids in blood samples during distillation of blood to obtain pure water for tritium analysis. Measuring tritium activity in plasma samples avoided this problem but required measurement of, and correction for, the dry matter content in plasma. Desiccation to constant mass by lyophilization or oven-drying also overestimated the amount of water actually in the bodies of chukar partridges by 1.4% of body mass, because these values included water adsorbed onto the outside of feathers. When desiccating defeathered carcasses, oven-drying at 70 degrees C yielded TBW values identical to those obtained from lyophilization, but TBW was overestimated (0.5% of body mass) by drying at 100 degrees C due to loss of organic substances as well as water.

  2. 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.

  3. Brain and CSF water and ions during dilutional and isosmotic hyponatremia in the rat.

    PubMed

    Melton, J E; Nattie, E E

    1983-05-01

    Dilutional (DH) and isosmotic (IH) hyponatremia (plasma [Na+] = 103-109 meq/l) were produced in conscious rats over 3-6 h by intraperitoneal injection of water or mannitol Ringer solution. During DH, CSF [Na+], [Cl-], and osmolality decreased as predicted by passive dilution by the water load. During IH, these variables exhibited little change. Brain water was unchanged during IH despite significant reduction of brain Na+ and Cl- content suggesting that tissue ions lost were replaced by other osmoles. During DH, brain water increased but less than predicted by passive osmotic equilibration. Cell volume increased as predicted by passive swelling while the extracellular volume (Cl space) decreased. Tissue K+ content decreased by a small but significant amount. Tissue Na+ and Cl- decreased by 21 and 28%. This pattern of fluid compartmental and electrolyte changes suggests that brain volume regulation during acute DH occurs via reduction of extracellular volume as cells swell. This may result from bulk flow of extracellular fluid to CSF or from ion and water movement across the blood-brain barrier.

  4. Comparison of the kinetics of chain aggregation and chain collapse in dilute polymer solutions.

    PubMed

    Maki, Yasuyuki; Dobashi, Toshiaki; Nakata, Mitsuo

    2008-10-01

    The rates of chain aggregation of poly(methyl methacrylate) (PMMA) in acetonitrile (AcN) and in the mixed solvent of AcN+water (10 vol%) were determined by static light scattering and compared with the rates of chain collapse [Maki, J. Chem. Phys. 126, 134901 (2007)]. Dilute solutions of PMMA with the molecular weight m{w}=6.4 x 10{6} and in the concentration range of (0.8-5)x10;{-4}gcm;{3} were quenched below the cloud point, and the weight-average molecular weight M{w} and z -average square radius of gyration S;{2}_{z} for clusters of PMMA chains were measured as a function of the time t after the quench and the concentration c . The measurement of chain aggregation was carried out up to the cluster size of M{w}m{w} approximately 30 , which required time periods of hours to several days depending on the concentration and solvent. The chain aggregation in AcN+water occurred much faster than that in AcN. The growth of clusters in both the solvents was represented by the exponential function as M{w} approximately e;{gct} and S;{2}_{z} approximately e{hct} , where g and h represent the intrinsic rate of chain aggregation. The ratio sigma of the intrinsic rate in AcN+water to that in AcN was estimated to be 9 by taking a rough average of the ratios 9.4 obtained from g and 8.8 from h . This value is comparable to the ratio 11 of the rate of chain collapse of PMMA in AcN+water (10 vol%) to that in AcN. This close value of the ratios indicates that the nature of solvent would affect the rates of chain collapse and chain aggregation through a similar mechanism.

  5. Sugar yields from dilute oxalic acid pretreatment of maple wood compared to those with other dilute acids and hot water.

    PubMed

    Zhang, Taiying; Kumar, Rajeev; Wyman, Charles E

    2013-01-30

    Dilute oxalic acid pretreatment was applied to maple wood to improve compatibility with downstream operations, and its performance in pretreatment and subsequent enzymatic hydrolysis was compared to results for hydrothermal and dilute hydrochloric and sulfuric acid pretreatments. The highest total xylose yield of ∼84% of the theoretical maximum was for both 0.5% oxalic and sulfuric acid pretreatment at 160 °C, compared to ∼81% yield for hydrothermal pretreatment at 200 °C and for 0.5% hydrochloric acid pretreatment at 140 °C. The xylooligomer fraction from dilute oxalic acid pretreatment was only 6.3% of the total xylose in solution, similar to results with dilute hydrochloric and sulfuric acids but much lower than the ∼70% value for hydrothermal pretreatment. Combining any of the four pretreatments with enzymatic hydrolysis with 60 FPU cellulase/g of glucan plus xylan in the pretreated maple wood resulted in virtually the same total glucose plus xylose yields of ∼85% of the maximum possible.

  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

    2011-10-04

    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. Production of silver nanoparticles in water solution by radiation treatment

    NASA Astrophysics Data System (ADS)

    Mikhailenko, M. A.; Korobeinikov, M. V.; Bryazgin, A. A.; Tolochko, B. P.

    2017-01-01

    Radiation-chemical synthesis of silver nanoparticles was studied. The silver nanoparticles in arabinogalactan (AG) water solution are stabilized in conglomerates, it is fixed by rise of additional bands in the optical absorption spectra. Pre-radiation treatment of AG causes crosslinking and oxidation. Pretreated AG solution increases the stability of conglomerates containing silver nanoparticles in case of dilution.

  8. A-type crystals from dilute solutions of short amylose chains.

    PubMed

    Montesanti, Nicole; Véronèse, Gabrielle; Buléon, Alain; Escalier, Pierre-Claude; Kitamura, Shinichi; Putaux, Jean-Luc

    2010-11-08

    Model A-type amylose single crystals were prepared by recrystallizing dextrins from acid-hydrolyzed native starch and narrow fractions of short chains of enzymatically synthesized amylose, in dilute water/acetone solutions. In most cases, spindle-shaped crystals with a sharp, round or flat apical end were formed, organized in rosettes or fan-like assemblies. The morphology and crystal size were shown to strongly depend on the average degree of polymerization (DP), distribution width (DW), and degree of branching of the chains. The largest and most clearly faceted single crystals were prepared using fractions of synthetic amylose. Typically, 5-10 μm long crystals were obtained from fractions with 17 ≤ DP ≤ 20 and DW ≤ 8. Chains with DP > 40 and a high polydispersity formed ill-defined networks of smaller crystallites. Fractions of branched and more polydisperse limit dextrins yielded crystals smaller than those obtained from narrow fractions of synthetic amylose. The morphological analysis of faceted single crystals combined with electron diffraction data confirmed that the double helices were oriented along the long dimension of the crystal and packed into lamellae with a parallelogram cross section defined by the a and b directions of the monoclinic unit cell of A-amylose. The lamellae are stacked along the c-axis that is oriented parallel but opposite to the growth direction of the crystal.

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

    SciTech Connect

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

    1994-12-01

    The recovery of propylene glycol from dilute aqueous solutions via reaction with formaldehyde to form 4-methyl-1,3-dioxolane or with acetaldehyde to form 2,4-dimethyl-1,3-dioxolane was studied experimentally. The equilibrium and kinetics of the reaction with formaldehyde were studied in systems catalyzed by Amberlite IR-120 ion exchange resin. The equilibrium constant ranged from 5.9 to 8.7 in the temperature range from 25 to 85 C, with no obvious trend with respect to temperature. The kinetics was found to be first-order in the concentrations of propylene glycol, formaldehyde, and Amberlite IR-120, with an activation energy of 102 kJ/mol. In the reaction with acetaldehyde, the equilibrium constant decreased from 18.1 at 40 C to 8.5 at 83 C. The kinetics was faster than with formaldehyde. The volatilities of 4-methyl-1,3-dioxolane and 2,4-dimethyl-1,3-dioxolane relative to water were 100 and 33, respectively. Of several solvents screened, aromatic hydrocarbons exhibited the highest distribution of 2,4-dimethyl-1,3-dioxolane from the aqueous into the organic phase. Recovery of propylene glycol by reactive distillation with formaldehyde or acetaldehyde is hampered by unfavorable chemical and phase equilibria. A process combining reaction and extraction into an organic solvent appears to be more attractive and substantially reduces the energy requirement, in comparison with a triple-effect evaporation process.

  10. 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…

  11. Taste does not determine daily intake of dilute sugar solutions in mice

    PubMed Central

    Beltran, F.; Benton, L.; Cheng, S.; Gieseke, J.; Gillman, J.; Spain, H. N.

    2010-01-01

    When a rodent licks a sweet-tasting solution, taste circuits in the central nervous system that facilitate stimulus identification, motivate intake, and prepare the body for digestion are activated. Here, we asked whether taste also determines daily intake of sugar solutions in C57BL/6 mice. We tested several dilute concentrations of glucose (167, 250, and 333 mM) and fructose (167, 250, and 333 mM). In addition, we tested saccharin (38 mM), alone and in binary mixture with each of the sugar concentrations, to manipulate sweet taste intensity while holding caloric value constant. In experiment 1, we measured taste responsiveness to the sweetener solutions in two ways: chorda tympani nerve responses and short-term lick tests. For both measures, the mice exhibited the following relative magnitude of responsiveness: binary mixtures > saccharin > individual sugars. In experiment 2, we asked whether the taste measures reliably predicted daily intake of the sweetener solutions. No such relationship was observed. The glucose solutions elicited weak taste responses but high daily intakes, whereas the fructose solutions elicited weak taste responses and low daily intakes. On the other hand, the saccharin + glucose solutions elicited strong taste responses and high daily intakes, while the saccharin + fructose solutions elicited strong taste responses but low daily intakes. Overall, we found that 1) daily intake of the sweetener solutions varied independently of the magnitude of the taste responses and 2) the solutions containing glucose stimulated substantially higher daily intakes than did the solutions containing isomolar concentrations of fructose. Given prior work demonstrating greater postoral stimulation of feeding by glucose than fructose, we propose that the magnitude of postoral nutritive stimulation plays a more important role than does taste in determining daily intake of dilute sugar solutions. PMID:20702804

  12. Removal of transition metals from dilute aqueous solution by carboxylic acid group containing absorbent polymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new carboxylic acid group containing resin with cation exchange capacity, 12.67 meq/g has been used to remove Cu2+, Co2+ and Ni2+ ions from dilute aqueous solution. The resin has Cu2+, Co2+ and Ni2+ removal capacity, 216 mg/g, 154 mg/g and 180 mg/g, respectively. The selectivity of the resin to ...

  13. Transport in very dilute solutions of 3He in superfluid 4He

    NASA Astrophysics Data System (ADS)

    Baym, Gordon; Beck, D. H.; Pethick, C. J.

    2013-07-01

    Motivated by a proposed experimental search for the electric dipole moment of the neutron (nEDM) utilizing neutron-3He capture in a dilute solution of 3He in superfluid 4He, we derive the transport properties of dilute solutions in the regime where the 3He are classically distributed and rapid 3He-3He scatterings keep the 3He in equilibrium. Our microscopic framework takes into account phonon-phonon, phonon-3He, and 3He-3He scatterings. We then apply these calculations to measurements by Rosenbaum [J. Low Temp. Phys.JLTPAC0022-229110.1007/BF00655864 16, 131 (1974)] and by Lamoreaux [Europhys. Lett.EULEEJ0295-507510.1209/epl/i2002-00408-4 58, 718 (2002)] of dilute solutions in the presence of a heat flow. We find satisfactory agreement of theory with the data, serving to confirm our understanding of the microscopics of the helium in the future nEDM experiment.

  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. THE INACTIVATION OF DILUTE SOLUTIONS OF CRYSTALLINE TRYPSIN BY X-RADIATION

    PubMed Central

    McDonald, Margaret R.

    1954-01-01

    The activity of dilute solutions of crystalline trypsin is destroyed by x-rays. The inactivation is an exponential function of the radiation dose. The reaction yield of inactivation is independent of the intensity at which the radiation is delivered or the quality of the x-rays. The reaction yield increases with increasing concentration of trypsin, varying from 0.06 to 0.7 micromoles per liter per 1000 r for trypsin solutions ranging from 1 x 10–7 to 2 x 10–4 M. PMID:13192318

  16. 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.

  17. Enthalpy changes upon dilution and ionization of poly(L-glutamic acid) in aqueous solutions.

    PubMed

    Godec, Andrej; Skerjanc, Joze

    2005-07-14

    The enthalpy changes accompanying the dilution and ionization of poly(L-glutamic acid) in water have been measured at 25 degrees C for two degrees of polymerization (DP = 115 and DP = 480) at various degrees of ionization, alpha, for a concentration range from about 0.2 to 0.002 monomol/L. The heat of dilution displays an unusual dependence on the degree of ionization, which is in sharp contrast to the behavior of other weak carboxylic polyelectrolytes, such as poly(acrylic acid). The exothermic heat effects observed at low values of alpha become endothermic for the region where the helix-coil transition is most pronounced, and for high degrees of ionization, they are exothermic again. Evidently, an endothermic heat effect, produced by an additional conformational transition in the dilution process, is superimposed on the exothermic enthalpy of dilution, and it overweighs the latter in the region of alpha where the conformational transition is prevailing. The calorimetric titration curve, which gives the dependence of the heat of ionization, deltaH(i), on alpha, has a maximum and is typical for poly(carboxylic acids) which undergo pH-induced conformational transition, such as poly(methacrylic acid). The values of deltaH(i) obtained at two polymer concentrations indicate that the enthalpy of ionization depends on the polypeptide concentration.

  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 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.

  20. 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.

  1. 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.

  2. Structure impact of two galactomannan fractions on their viscosity properties in dilute solution, unperturbed state and gel state.

    PubMed

    Gillet, Sébastien; Aguedo, Mario; Petrut, Raul; Olive, Gilles; Anastas, Paul; Blecker, Christophe; Richel, Aurore

    2017-03-01

    Two fractions of carob galactomannans (GM25 and GM80) were extracted at respectively 25°C and 80°C from crude locust bean gum. Those fractions having slightly different chemical structures, previously characterized, were studied for their viscosity properties over a wide range of concentrations: diluted solution, unperturbed state and gel state. For each of the physical properties, links to the chemical fine structure could be established, expanding knowledge on the topic: in dilute solution, GM25 is more soluble in water while GM80 seems to tend to self-association due to its structure as highlighted by intrinsic viscosity measurements ([η]GM25=9.96dLg(-1) and [η]GM80=4.04dLg(-1)). In unperturbed state, initial viscosities η0 were more important for GM80 fractions at 1% and 2% due to greater hyperentanglements (η0(GM80,1%)=9.9Pas; η0(GM80,2%)=832.0; Pa.s η0(GM25,1%)=3.1Pas; η0(GM25,2%)=45.1Pas). In gel state, hydrogels obtained from GM80 were also stronger (hardness GM80 (2%)=0.51N and hardness GM25 (2%)=0.11N), suggesting a much more important number of junction areas within the gel network. The findings discussed herein demonstrate the potential for new applications.

  3. 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.

  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.

  5. Solution behaviors and microstructures of PNIPAm-P123-PNIPAm pentablock terpolymers in dilute and concentrated aqueous solutions.

    PubMed

    Lu, Yanping; Chen, Tongquan; Mei, Aixiong; Chen, Tianyou; Ding, Yanwei; Zhang, Xinghong; Xu, Junting; Fan, Zhiqiang; Du, Binyang

    2013-06-07

    The solution behaviors and microstructures of poly(N-isopropylacrylamide)x-poly(ethylene oxide)20-poly(propylene oxide)70-poly(ethylene oxide)20-poly(N-isopropylacrylamide)x (PNIPAmx-PEO20-PPO70-PEO20-PNIPAmx or PNIPAmx-P123-PNIPAmx) pentablock terpolymers with various PNIPAm block lengths in dilute and concentrated aqueous solutions were investigated by micro-differential scanning calorimetry (micro-DSC), static and dynamic light scattering (SLS & DLS), and synchrotron small angle X-ray scattering (SAXS). Two lower critical solution temperatures (LCSTs) were observed for PNIPAmx-P123-PNIPAmx pentablock terpolymers in dilute solutions, which corresponded to LCSTs of PPO and PNIPAm blocks, respectively. The LCST of PPO block shifted from 24.4 °C to 29 °C when the length x of PNIPAm block increased from 10 to 97. The LCST of PNIPAm is around 34.5 °C-35.3 °C and less dependent on the block length x. The PNIPAmx-P123-PNIPAmx pentablock terpolymers formed "associate" structures and micelles with hydrophobic PNIPAm and PPO blocks as cores and soluble PEO blocks as coronas in dilute aqueous solutions at 20 °C and 40 °C, respectively, regardless of the relative lengths of PNIPAm, PPO and PEO blocks. The size of "associate" structures of PNIPAmx-P123-PNIPAmx pentablock terpolymers at 20 °C increased with increasing the length of PNIPAm block. The microstructures of PNIPAmx-P123-PNIPAmx hydrogels formed in concentrated aqueous solutions (40 wt%) were strongly dependent on the environmental temperatures and relative lengths of PNIPAm, PPO and PEO blocks as revealed by SAXS. Increasing the length of PNIPAm block weakened the order structures of PNIPAmx-P123-PNIPAmx hydrogels. The microstructures of PNIPAmx-P123-PNIPAmx hydrogels changed from mixed fcc and hex structures for PNIPAm10-P123-PNIPAm10 to isotropic structure for PNIPAm97-P123-PNIPAm97. Increasing temperature led to the transition from mixed hex and fcc structure to pure hex structure for PNIPAm10-P123-PNIPAm

  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. Dilute solution properties of Prunus armeniaca gum exudates: Influence of temperature, salt, and sugar.

    PubMed

    Fathi, Morteza; Mohebbi, Mohebbat; Koocheki, Arash; Hesarinejad, Mohammad Ali

    2017-03-01

    The aim of the current paper was to investigate the effect of different temperatures, salts and sugars on dilute solution properties of Prunus armeniaca gum exudates (PAGE) as a starting point to evaluate the potential utilization of this novel source of hydrocolloids in food and pharmaceutical systems. Berry number and the slope of master curve indicated that PAGE samples in all evaluated conditions were in dilute domain without coil overlapping and entanglement. Furthermore, the slope power law model also demonstrated that the molecular conformation of PAGE in all tested temperatures was close to rode-like. On the other hand, PAGE samples had random coil conformation in the presence of sugars and ions studied. Activation energy and chain flexibility of PAGE were found to be 0.83×10(7) (J/kg) and 997.3, respectively. This result revealed that temperature has a slight effect on intrinsic viscosity of PAGE solution, implying this gum can be introduced as a promising ingredient in food formulation that need to high stability against temperature. The data obtained in the present study and results thereof can be useful when considering the effect of additives generally used in food products and/or processing parameters like temperature in food systems.

  8. Influence of deacetylation on the rheological properties of xanthan-guar interactions in dilute aqueous solutions.

    PubMed

    Khouryieh, H A; Herald, T J; Aramouni, F; Bean, S; Alavi, S

    2007-04-01

    An oscillating capillary rheometer was used to investigate the effects of xanthan deacetylation on the viscoelastic properties and intrinsic viscosity of xanthan and guar mixtures in dilute aqueous solutions. Deacetylated xanthan exhibited a stronger synergistic interaction with guar than native xanthan did due to the destabilized helical structure and increased chain flexibility of the deacetylated xanthan. No gels were observed for all xanthan-guar mixtures. Native xanthan-guar mixtures exhibited a liquid-like behavior, whereas deacetylated xanthan-guar mixtures exhibited a gel-like behavior. The relative viscosity and elasticity of deacetylated xanthan-guar mixtures were much stronger than those for native xanthan-guar mixtures. The intrinsic viscosities of deacetylated xanthan-guar mixtures were higher than the calculated values assuming no interaction, whereas the intrinsic viscosities of native xanthan-guar mixtures were lower than the calculated values assuming no interaction, demonstrating that intermolecular binding occurred between the disordered segments of xanthan and guar gum in dilute aqueous solutions.

  9. Spin Transport in Dilute, Spin-Polarized Solutions of Helium-Three in Helium-Four

    NASA Astrophysics Data System (ADS)

    McAllaster, Donald R.

    1992-01-01

    We have investigated ^3He spin diffusion in two dilute solutions of ^3 He in ^4He, with atomic fraction x^3=1.82times 10^{-3} and 6.26 times 10 ^{-4}, spin-polarized by an 8 T field. We do not find evidence that the diffusion coefficient for spins transverse to the average magnetization (D _|) declines or saturates at temperatures down to 0.20T_{rm F}, contrary to previous experiment (Gully and Mullin 1984) but in accord with current theory. We have compared our measurements with the latest theory of Jeon and Mullin (1991); our data is mostly in good agreement with their theory if a slightly modified version of a ^3 He-^3He interaction due to Ebner (1967) is used. The congruence between data and theory supports the conclusion that the s-wave approximation to the interaction is not useful for transport calculations even for these rather dilute solutions. There may be an one unresolved discrepancy: our diffusion constant for the lowest concentration at the lowest temperatures is 25% higher than theory predicts. This could be due to a polarization dependance for D_| or to a modification of the boundary condition by a bound ^3He state, or possibly due to errors in the theoretical calculation.

  10. Extensional Relaxation Times and Pinch-off Dynamics of Dilute Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Dinic, Jelena; Zhang, Yiran; Jimenez, Leidy; Sharma, Vivek

    2015-11-01

    We show that visualization and analysis of capillary-driven thinning and pinch-off dynamics of the columnar neck in an asymmetric liquid bridge created by dripping-onto-substrate can be used for characterizing the extensional rheology of complex fluids. Using a particular example of dilute, aqueous PEO solutions, we show the measurement of both the extensional relaxation time and extensional viscosity of weakly elastic, polymeric complex fluids with low shear viscosity η< 20 mPa .s and relatively short relaxation time, λ <1 ms. Characterization of elastic effects and extensional relaxation times in these dilute solutions is beyond the range measurable in the standard geometries used in commercially available shear and extensional rheometers (including CaBER, capillary breakup extensional rheometer). As the radius of the neck that connects a sessile drop to a nozzle is detected optically, and the extensional response for viscoelastic fluids is characterized by analyzing their elastocapillary self-thinning, we refer to this technique as optically-detected elastocapillary self-thinning dripping-onto-substrate (ODES-DOS) extensional rheometry.

  11. Phase separation in dilute solutions of 3He in solid 4He

    NASA Astrophysics Data System (ADS)

    Huan, C.; Yin, L.; Xia, J. S.; Candela, D.; Cowan, B. P.; Sullivan, N. S.

    2017-03-01

    We report the results of studies of the phase separation of solid solutions of dilute concentrations of 3He in 4He. The temperatures and the kinetics of the phase separation were determined from NMR experiments for 3He concentrations 1.6 ×10-5solution theory as augmented by Edwards and Balibar [Phys. Rev. B 39, 4083 (1989), 10.1103/PhysRevB.39.4083]. The growth of 3He droplets shows a t1 /3 time dependence at long times consistent with Ostwald ripening.

  12. Crossover Leung-Griffiths model and the phase behavior of dilute aqueous ionic solutions

    NASA Astrophysics Data System (ADS)

    Belyakov, M. Yu.; Kiselev, S. B.; Rainwater, J. C.

    1997-08-01

    A new parametric crossover model for the phase behavior of a binary mixture is presented that corresponds to the Leung-Griffiths model in the critical region and is transformed into the regular classical expansion far away from the critical point. The model is optimized to, and leads to excellent agreement with, isothermal vapor-liquid equilibrium data for dilute aqueous solutions of sodium chloride by Bischoff and co-workers. It then accurately predicts constant-composition phase equilibrium loci as measured by independent workers. This crossover model is therefore capable of representing the thermodynamic surface of ionic solutions in a large range of temperatures and densities around the critical points of vapor-liquid equilibrium.

  13. Reaction of trace mercury in natural gas with dilute polysulfide solutions in a packed column

    SciTech Connect

    Not Available

    1991-12-01

    This paper reports that the natural gas produced around the world can contain traces of mercury which have to be removed. It is difficult to purify gas to desired mercury levels using conventional techniques. By scrubbing with dilute polysulfide solution, the residual mercury in the gas can be removed from about 0.1 to below 0.01 ppb, a reduction of 90%. In this system, the gas is passed through a packed tower wetted with a solution containing 3 ppm of polysulfide salt. Stainless steel packings are effective for this application. In addition to promoting gas-liquid contact, the stainless steel packings adsorb and concentrate polysulfides which react with Hg in the gas to form insoluble HgS, and thus remove Hg from the gas.

  14. 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.

  15. 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

  16. Water dynamics near solutes and surfaces

    NASA Astrophysics Data System (ADS)

    Moilanen, David Emil

    stretch of dilute HOD in H2O confined in the reverse micelles provides a probe of the dynamics of the confined water. The characteristic vibrational lifetime and orientational correlation time of interfacial water are determined from a detailed investigation of the frequency dependence of the vibrational population relaxation and orientational anisotropy. The properties of interfacial water are independent of size and geometry for large reverse micelles and lamellar structures, indicating that it is the presence of an interface, not the geometry of the system or a specific confining length scale that affects the dynamics of interfacial water. As the reverse micelle size is decreased, the number of water molecules becomes small enough that the collective nature of water reorientation begins to cause the water away from the interface to be affected by the presence of the interface. One of the most fundamental water-solute interactions is the transport of ions by water. This process is governed by the exchange of water molecules in the solvation shell of the ion. Solvation shell exchange is studied using pump-probe and 2D-IR Chemical Exchange Spectroscopy of a mixture of water and sodium tetrafluoroborate (NaBF4). The timescale for solvation shell exchange is extracted by simultaneously fitting the chemical exchange data, the vibrational population relaxation and the orientational anisotropy data to a kinetic model. Anion solvation shell exchange occurs on a timescale of approximately seven picoseconds, allowing rapid ion transport in solution.

  17. 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.

  18. Optical and Rheological Properties of a Semi-Diluted Equimolar Solution of Cetyltrimethylammonium Bromide and Potassium Bromide

    NASA Astrophysics Data System (ADS)

    Decruppe, J. P.; Cappelaere, E.; Cressely, R.

    1997-02-01

    We report in this paper the results of rheological and optical experiments performed on a semi-diluted viscoelastic solution of cetyltrimethylammonium bromide (CTAB) in water with sodium bromide at a concentration of 0.3 M l^{-1} in surfactant and salt. This concentration in surfactant is much smaller than the concentration which gives a nematic phase at rest. The solution behaves like a Maxwell fluid with a single relaxation time. When submitted to a shear flow, this solution shows a behaviour typical of a system undergoing a phase transition. When observed between crossed polarizer and analyzer, the gap of the Couette cell appears divided in two bands the optical properties of which are different; in rheology, the curves σ(dot{γ}) are also characteristic of these systems where the shear stress presents a plateau extending between two critical values, dot{γ}_{1c}, and dot{γ}_{2c} of the shear rate. We finally compare the results with previous experiments performed on a concentrated solution of CTAB containing no salt.

  19. Efflux of red cell water into buffered hypertonic solutions.

    PubMed

    OLMSTEAD, E G

    1960-03-01

    Buffered NaCl solutions hypertonic to rabbit serum were prepared and freezing point depressions of each determined after dilution with measured amounts of water. Freezing point depression of these dilutions was a linear function of the amount of water added. One ml. of rabbit red cells was added to each 4 ml. of the hypertonic solutions and after incubation at 38 degrees C. for 30 minutes the mixture was centrifuged and a freezing point depression determined on the supernatant fluid. The amount of water added to the hypertonic solutions by the red cells was calcuated from this freezing point depression. For each decrease in the freezing point of -0.093 degrees C. of the surrounding solution red cells gave up approximately 5 ml. of water per 100 ml. of red cells in the range of -0.560 to -0.930 degrees C. Beyond -0.930 degrees C. the amount of water given up by 100 ml. of red cells fits best a parabolic equation. The maximum of this equation occurred at a freezing point of the hypertonic solution of -2.001 degrees C. at which time the maximum amount of water leaving the red cells would be 39.9 ml. per 100 ml. of red cells. The data suggest that only about 43 per cent of the red cell water is available for exchange into solutions of increasing tonicity.

  20. Theory and Simulation of Cholesteric Film Formation Flows of Dilute Collagen Solutions.

    PubMed

    Aguilar Gutierrez, O F; Rey, Alejandro D

    2016-11-15

    Dilute isotropic collagen solutions are usually flow processed into monodomain chiral nematic thin films for obtaining highly ordered materials by a multistep process that starts with complex inhomogeneous flow kinematics. Here we present rigorous theory and simulation of the initial precursors during flow steps in cholesteric collagen film formation. We first extract the molecular shape parameter and rotational diffusivity from previously reported simple shear data of dilute collagen solutions, where the former leads the reactive parameter (tumbling function) which determines the net effect of vorticity and strain rate on the average orientation and where the latter establishes the intensity of strain required for flow-birefringence, both crucial quantities for controlled film formation flow. We find that the tumbling function is similar to those of rod-like lyotropic liquid crystalline polymers and hence it is predicted that they would tumble in the ordered high concentration state leading to flow-induced texturing. The previously reported experimental data is well fitted with rotational diffusivities whose order of magnitude is consistent to those of other biomacromolecules. We then investigate the response of the tensor order parameter to complex flow kinematics, ranging from pure vorticity, through simple shear, to extensional flow, as may arise in typical flow casting and film flows. The chosen control variable to produce precursor cholesteric films is the director or average orientation, since the nematic order is set close to typical values found in concentrated cholesteric type I collagen solutions. Using the efficient four-roll mill kinematics, we summarize the para-nematic structure-flow process diagram in terms of the director orientation and flow type. Using analysis and computation, we provide a parametric envelope that is necessary to eventually produce well-aligned cholesteric films. We conclude that extensional flow is an essential ingredient of

  1. The electroremoval of copper from dilute waste solutions using Swiss-roll electrode cell

    NASA Astrophysics Data System (ADS)

    Saba, A. E.; El Sherif, A. E.; Elsayed, E. M.

    2007-10-01

    Copper is usually present in concentrations less than 5 g/L-1 in dilute waste solutions. The low concentrations make these solutions unsuitable for the electro-flow owinning processes via conventional electrolysis cells. Unconventional, two-and three-dimensional electrode cells with relatively large cathodic area are essential for such treatment. Different types of cells are mentioned in the literature. Among these cells, the two-dimensional Swiss-roll cell (SR) is considered in this study. The effects of cathodic current densities, initial copper concentrations, free sulfuric acid concentration, the presence of iron and zinc cations, and the rate of flow of the solution on both the cathodic current efficiency and power consumption were studied. Copper was removed from synthetic and industrial mixtures of Cu/Fe/Zn sulfate solutions to less than 5 ppm with power consumptions of 10.326 kWh/kg-1 and 8.61 kWh/kg-1, respectively. The correlation between the SR cell and packed-column cell on such treatment was also considered.

  2. 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.

  3. [Forming the nanosized molecular assemblies (nanoassociates) is a key to understand the properties of highly diluted aqueous solutions].

    PubMed

    Konovalov, A I; Ryzhkina, I S; Murtazina, L I; Kiseleva, Iu V

    2014-01-01

    In the present study it was shown that biological effects of highly diluted aqueous solutions were due to the formation of nano-sized (up to 400 nm) molecular assemblies, called nanoassociates mainly consisting of aqueous molecules (up to 500 million) under the influence of two effectors: solute and external electromagnetic fields.

  4. 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

  5. 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.

  6. Wavelet treatment of the intrachain correlation functions of homopolymers in dilute solutions

    NASA Astrophysics Data System (ADS)

    Fedorov, M. V.; Chuev, G. N.; Kuznetsov, Yu. A.; Timoshenko, E. G.

    2004-11-01

    Discrete wavelets are applied to the parametrization of the intrachain two-point correlation functions of homopolymers in dilute solutions obtained from Monte Carlo simulations. Several orthogonal and biorthogonal basis sets have been investigated for use in the truncated wavelet approximation. The quality of the approximation has been assessed by calculation of the scaling exponents obtained from the des Cloizeaux ansatz for the correlation functions of homopolymers with different connectivities in a good solvent. The resulting exponents are in better agreement with those from recent renormalization group calculations as compared to the data without the wavelet denoising. We also discuss how the wavelet treatment improves the quality of data for correlation functions from simulations of homopolymers at varied solvent conditions and of heteropolymers.

  7. Temperature dependence of the activity of Al in dilute Ni(Al) solid solutions

    SciTech Connect

    Jiang Yong; Smith, J. R.; Evans, A. G.

    2006-12-01

    Activities of dilute Al solid solutions in Ni are determined from a first-principles approach. Both thermal lattice vibration and electronic contributions to free energies are considered and compared. Vibrational contributions tend to dominate the temperature dependencies of the free energies, though electron thermal effects are significant. Calculations show opposing temperature trends for the formation enthalpies and entropies, leading to a partial cancellation of their role in the overall energetics. Nevertheless, their remaining temperature effects are strong. Over the temperature range, 400 K

  8. Morphological study of magnesium hydroxide nanoparticles precipitated in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Henrist, C.; Mathieu, J.-P.; Vogels, C.; Rulmont, A.; Cloots, R.

    2003-02-01

    Among other applications, magnesium hydroxide is commonly used as a flame-retardant filler in composite materials, as well as a precursor for magnesium oxide refractory ceramic. The microstructure of the powder is of prime importance in both technical applications. The influence of synthesis parameters on the morphological characteristics of magnesium hydroxide nanoparticles precipitated in dilute aqueous medium was studied. Several parameters were envisaged such as chemical nature of the base precipitant, type of counter-ion, temperature and hydrothermal treatment. Special attention was given to the obtaining of platelet-shaped, nanometric and de-agglomerated powders. The powders were characterized in terms of particle size distribution, crystal habits, morphology and ability to be re-dispersed in water. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and laser diffusion analyses were used for this purpose.

  9. 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.

  10. A Statistical-Mechanical Theory of Fibril Formation in Dilute Protein Solutions

    PubMed Central

    van Gestel, Jeroen; de Leeuw, Simon W.

    2006-01-01

    We outline a theoretical treatment that describes fibril formation in dilute protein solutions. For this, we combine a theory describing self-assembly and conformational transition with a description of the lateral association of linear chains. Our statistical-mechanical model is able to predict the mean degree of polymerization and the length of the fibrils and their precursors, as well as the weight fractions of the different aggregated species in solution. We find that there appear to exist two regimes as a function of concentration, and as a function of the free energies of protein association: one in which low-molecular weight compounds dominate and one in which the fibrils do. The transition between these regimes can be quite sharp, and becomes sharper as more filaments are allowed to associate into a single fibril. The fraction of fibrils consisting of less than the maximum allowed number of filaments turns out to be negligible, in agreement with experimental studies, where the fibril thickness is found to be practically monodisperse. In addition, we find that the description of the fibril ends has a large effect on the predicted fibril length. PMID:16603504

  11. A statistical-mechanical theory of fibril formation in dilute protein solutions.

    PubMed

    van Gestel, Jeroen; de Leeuw, Simon W

    2006-05-01

    We outline a theoretical treatment that describes fibril formation in dilute protein solutions. For this, we combine a theory describing self-assembly and conformational transition with a description of the lateral association of linear chains. Our statistical-mechanical model is able to predict the mean degree of polymerization and the length of the fibrils and their precursors, as well as the weight fractions of the different aggregated species in solution. We find that there appear to exist two regimes as a function of concentration, and as a function of the free energies of protein association: one in which low-molecular weight compounds dominate and one in which the fibrils do. The transition between these regimes can be quite sharp, and becomes sharper as more filaments are allowed to associate into a single fibril. The fraction of fibrils consisting of less than the maximum allowed number of filaments turns out to be negligible, in agreement with experimental studies, where the fibril thickness is found to be practically monodisperse. In addition, we find that the description of the fibril ends has a large effect on the predicted fibril length.

  12. 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.

  13. The enthalpies of solution of VOCl3 in dilute solutions of sodium hydroxide and the standard enthalpy of formation of liquid VOCl3

    NASA Astrophysics Data System (ADS)

    Dmitrieva, N. G.; Romodanovskii, P. A.; Gridchin, S. N.; Vorob'ev, P. N.

    2010-01-01

    The enthalpies of solution of liquid vanadium oxytrichloride in dilute solutions of sodium hydroxide were determined by direct calorimetric measurements at 298.15 K and ionic strength values I = 0.3, 0.5, and 1.0 (NaClO4). The experimental data were used to calculate the standard enthalpy of formation of liquid VOCl3.

  14. Enthalpy of solution of VOCl3 in dilute sodium hydroxide solutions and the standard enthalpy of formation of the HVO{4/2-} ion

    NASA Astrophysics Data System (ADS)

    Romodanovskii, P. A.; Vorob'ev, P. N.; Dmitrieva, N. G.; Gridchin, S. N.

    2007-12-01

    The calorimetric enthalpies of solution of liquid vanadium oxytrichloride in dilute sodium hydroxide solutions were measured at 298.15 K and ionic strengths I = 0.5, 1.0, or 1.5 (NaClO4). The standard enthalpy of formation of the HVO{4/2-} ion was calculated from the measured data.

  15. 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.

  16. [Functional analysis of diluted solutions of human hemoglobin by using Oximeter-3000 WTW equipped with Trioxmatic-300 electrode].

    PubMed

    Ricco, G; David, O; Rabino-Massa, E

    1998-04-01

    The oxygen carrying capacity of dilute solutions of hemoglobin from normal human adults was examined, by using the above indicated Oximeter. The results show that, if the pO2s are compared with those drawn from the Oximeter-539 WTW (a simpler instrument) carrying the same oxygen electrode, there is a good correspondence between the data drawn from both the instruments. The advantage of the former is that pO2s are measure in mBr, whereas the latter measures the oxygen of the aqueous solutions in mg/l; then mg must be converted into Torr pO2. Since both instruments are usually employed in the oxygen measurement of waste waters of earth, another conclusion is that their sensitivity also allows the use in the bio-medical (and zoological) field. In fact, the data obtained agree with those of recent literature on the subject, which are mainly drawn from automated and sophisticated apparatuses specifically built at this purpose.

  17. Creatine Supplementation Increases Total Body Water in Soccer Players: a Deuterium Oxide Dilution Study.

    PubMed

    Deminice, R; Rosa, F T; Pfrimer, K; Ferrioli, E; Jordao, A A; Freitas, E

    2016-02-01

    This study aimed to evaluate changes in total body water (TBW) in soccer athletes using a deuterium oxide dilution method and bioelectrical impedance (BIA) formulas after 7 days of creatine supplementation. In a double-blind controlled manner, 13 healthy (under-20) soccer players were divided randomly in 2 supplementation groups: Placebo (Pla, n=6) and creatine supplementation (CR, n=7). Before and after the supplementation period (0.3 g/kg/d during 7 days), TBW was determined by deuterium oxide dilution and BIA methods. 7 days of creatine supplementation lead to a large increase in TBW (2.3±1.0 L) determined by deuterium oxide dilution, and a small but significant increase in total body weight (1.0±0.4 kg) in Cr group compared to Pla. The Pla group did not experience any significant changes in TBW or body weight. Although 5 of 6 BIA equations were sensitive to determine TBW changes induced by creatine supplementation, the Kushner et al. 16 method presented the best concordance levels when compared to deuterium dilution method. In conclusion, 7-days of creatine supplementation increased TBW determined by deuterium oxide dilution or BIA formulas. BIA can be useful to determine TBW changes promoted by creatine supplementation in soccer athletes, with special concern for formula choice.

  18. Comparison of two dilution rates on canine semen quality after cryopreservation in a coconut water extender.

    PubMed

    de Cássia Soares Cardoso, Rita; Silva, Alexandre Rodrigues; da Silva, Lúcia Daniel Machado

    2006-05-01

    The objective of the present study was to evaluate the effect of sperm dilution (one part semen:one part extender or at 200 x 10(6) spermatozoa/mL) using a coconut water extender on the post-thaw sperm quality. Twelve ejaculates were collected from six dogs. Semen was divided into two aliquots, one for dilution one part semen:one part extender (group 1) and another for a concentration of 200 x 10(6) spermatozoa/mL (group 2). Semen was initially extended at 37 degrees C at a proportion of one part semen:half part extender (1:1/2) for group 1 (A-fraction). For group 2, the volume for a concentration of 200 x 10(6) spermatozoa/mL was calculated and a half of this volume was used for the initial dilution (A-fraction, 37 degrees C). Coconut water extender containing 20% egg yolk was used for this initial dilution in both groups. After dilution, the semen was cooled for 40 min in a thermal box (15 degrees C) and for 30 min in a refrigerator. The other half of the extender (B-fraction) containing egg yolk and glycerol (12%) was added to semen in both groups. Subsequently, the final concentration of glycerol in the extender was 6%. Ejaculates were frozen in 0.25 mL straws 5 cm above the surface of liquid nitrogen and stored at -196 degrees C. After 1 week, straws were thawed at 37 degrees C for 1 min and the microscopic criteria were evaluated. The dilution method had no influence on sperm motility, vigor and normal spermatozoa (71.4 compared with 67.7%). There was no effect of dog, ejaculate within male on post-thaw semen quality. Moreover, there was not a male x treatment interaction. Both treatments were efficient in preserving sperm quality.

  19. 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.

  20. Influence of second virial coefficient and persistence length on dilute solution polymer conformation.

    PubMed

    Haidar Ahmad, Imad A; Striegel, André M

    2011-02-01

    The effect of different types of short- and long-range intrachain interactions along the polymeric backbone on the persistence length of a polymer, as well as on other properties such as solvation (characterized by the second virial coefficient), dilute solution conformation, specific refractive index increment, and intrinsic viscosity, were studied using multi-detector size-exclusion chromatography and off-line techniques. The polymers in this study, namely, polystyrene (PS), poly(vinyl chloride) (PVC), and poly(p-vinylbenzyl chloride) (PpVBC), were chosen based on intrachain interactions specific to each, intrachain repulsion in PVC, attraction in PS, and hindered attraction in PpVBC, and also based on a coincidence in molar mass averages and distributions between the polymers. The latter allowed polymeric properties of the three polymers to be compared to each other at the same molar mass and/or degree of polymerization. From the comparisons emerged the effects of intrachain repulsion between consecutive monomers and of the second virial coefficient on chain stiffness and solvation. The increase in the second virial coefficient corresponded to an increase in both polymer solvation and rigidity, while increased intrachain repulsion between consecutive monomers increased polymer solvation while decreasing chain rigidity.

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

    PubMed

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

    2014-10-07

    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.

  2. 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.

  3. Viscometric Studies in Dilute Solution Mixtures of Chitosan and Microcrystalline Chitosan with Poly(vinyl alcohol).

    PubMed

    Lewandowska, Katarzyna

    2013-01-01

    The viscosity behavior of aqueous mixtures formed by a polyelectrolyte (A) and a neutral polymer (B), such as chitosan/poly(vinyl alcohol) (Ch/PVA) and microcrystalline chitosan/poly(vinyl alcohol) (MCCh/PVA), have been investigated at 25 °C. The intrinsic viscosity and the viscosity interaction parameter of each polymer in 0.1 mol·dm(-3) CH3COOH/0.2 mol·dm(-3) NaCl solution as well as the ternary systems (polymer A/polymer B/solvent) have been determined and have served for estimation of the miscibility of different polymer mixtures by means of the method of classical dilution. By comparing the experimental and ideal viscosity data it is clearly seen that the satisfaction of the miscibility criterion depends on the definition of the ideal parameter [Formula: see text]. If the [Formula: see text] parameter is defined according to the Krigbaum-Wall criterion and Garcia criterion, the investigated blends of Ch/PVA satisfy the miscibility criterion. In the case of MCCh/PVA blends, the polymeric components show poor miscibility. Additionally, the viscosity results show that the degree of miscibility depends on the molecular weight of chitosan and on the degree of PVA hydrolysis.

  4. Regeneration of basic sorbents used in the recovery of acetic acid from dilute aqueous solution

    SciTech Connect

    Ng, M.; King, C.J.

    1988-10-01

    The regeneration of basic sorbents used in the recovery of dilute aqueous acetic acid was explored. The regeneration methods studied were solvent leaching and vaporization. The resins used were weak base anion exchange resins, Dow Chemical Company's Dowex MWA-1 (tertiary amine resin) and Celanese Corporation's Aurorez (polybenzimidazole resin). The equilibrium between the aqueous acetic acid solution and the resins was measured in batch experiments. The composite isotherms calculated from these data wee comparable to those of other researchers. Methanol was used as the solvent to leach acetic acid from the resin. The equilibrium data from the batch experiments were used in the local-equilibrium theory of fixed-bed devices to model the desorption behavior of acetic acid in methanol. Both sorption and desorption equilibrium data were used in chemical complexation models to obtain sorption affinities and capacities of the resin for acetic acid. However, the amount of methanol needed to achieve a high degree of regeneration was too large to be economical. 15 refs., 25 figs., 3 tabs.

  5. A quasichemical approach for protein-cluster free energies in dilute solution

    NASA Astrophysics Data System (ADS)

    Young, Teresa M.; Roberts, Christopher J.

    2007-10-01

    Reversible formation of protein oligomers or small clusters is a key step in processes such as protein polymerization, fibril formation, and protein phase separation from dilute solution. A straightforward, statistical mechanical approach to accurately calculate cluster free energies in solution is presented using a cell-based, quasichemical (QC) approximation for the partition function of proteins in an implicit solvent. The inputs to the model are the protein potential of mean force (PMF) and the corresponding subcell degeneracies up to relatively low particle densities. The approach is tested using simple two and three dimensional lattice models in which proteins interact with either isotropic or anisotropic nearest-neighbor attractions. Comparison with direct Monte Carlo simulation shows that cluster probabilities and free energies of oligomer formation (ΔGi0) are quantitatively predicted by the QC approach for protein volume fractions ˜10-2 (weight/volume concentration ˜10gl-1) and below. For small clusters, ΔGi0 depends weakly on the strength of short-ranged attractive interactions for most experimentally relevant values of the normalized osmotic second virial coefficient (b2*). For larger clusters (i ≫2), there is a small but non-negligible b2* dependence. The results suggest that nonspecific, hydrophobic attractions may not significantly stabilize prenuclei in processes such as non-native aggregation. Biased Monte Carlo methods are shown to accurately provide subcell degeneracies that are intractable to obtain analytically or by direct enumeration, and so offer a means to generalize the approach to mixtures and proteins with more complex PMFs.

  6. 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

    2007-02-07

    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.

  7. 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.

  8. 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.

  9. 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.

  10. Infinite dilution partial molar properties of aqueous solutions of nonelectrolytes. 1. Equations for partial molar volumes at infinite dilution and standard thermodynamic functions of hydration of volatile nonelectrolytes over wide ranges of conditions

    SciTech Connect

    Plyasunov, A.V.; O'Connell, J.P.; Wood, R.H.

    2000-02-01

    A semitheoretical expression for partial molar volumes at infinite dilution of aqueous nonelectrolyte solutes has been developed employing the collection of properties from fluctuation solution theory for use over wide ranges of temperature and pressure. The form of the solution expression was suggested by a comparison of solute/solvent and solvent/solvent direct correlations function integrals (DCFI). The selection of solvent density and compressibility as model variables provides a correct description in the critical region while second virial coefficients have been used to give a rigorous expression in the low density region. The formulation has been integrated to obtain analytic expressions for thermodynamic properties of hydration at supercritical temperatures. The equation is limited to solutes for which B{sub 12} (the second cross virial coefficient between water and a solute molecule) is known or can be estimated. Regression of the three remaining parameters gives good correlations of the available experimental data. A strategy for estimating these parameters allows prediction from readily available data.

  11. Interactions between ring polymers in dilute solution studied by Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Suzuki, Jiro; Takano, Atsushi; Matsushita, Yushu

    2015-01-01

    The second virial coefficient, A2, for trivial-ring polymers in dilute condition was estimated from a Metropolis Monte Carlo (MC) simulation, and the temperature dependence of A2 has been discussed with their Flory's scaling exponent, ν, in Rg ∝ Nν, where Rg is radius of gyration of a polymer molecule. A limited but not too small number of polymer molecules were employed in the simulation, and the A2 values at various temperatures were calculated from the molecular density fluctuation in the solution. In the simulation, the topology of ring polymers was kept, since chain crossing was prohibited. The excluded volume effects can be screened by the attractive force between segments, which depends on the temperature, Tα, defined in the Metropolis MC method. Linear and trivial-ring polymers have the ν value of 1/2 at Tα = 10.605 and 10.504. At Tα = 10.504, the excluded volume effects are screened by the attractive force generated between segments in a ring polymer, but the A2 value for ring polymers is positive. Thus, the temperature at A2 = 0 for a ring polymer is lower than that at ν = 1/2, and this fact can be explained with the following two reasons. (a) Rg value for a ring polymer is much smaller than that for a linear polymer at the same temperature and molecular weight, where interpenetration of a ring polymer chain into neighboring chains is apparently less than a linear chain. (b) The conformation of trivial rings can be statistically described as a closed random walk at ν = 1/2, but their topologies are kept, being produced topological constraints, which strongly relate not only to the long-distance interaction between segments in a molecule but also the inter-molecular interaction.

  12. Molecular imaging of shear-induced polymer migration near a surface in dilute and semidilute solutions

    NASA Astrophysics Data System (ADS)

    Fang, Lin

    The goal of our research is to optically visualize shear-induced polymer migration near a surface on the single molecular level, and to enhance current understanding of interactions between flowing polymer solutions with surfaces. By using epi-fluorescence microscopy, we measured the mean fractional stretch and concentrations of lambda-phage DNA molecules above a glass surface in shear flows in a microchannel and a torsional shear cell. We find that DNA molecules are driven away to create a depletion layer near the surface. The shear-induced migration is enhanced with a larger depletion layer at high Weissenberg number (Wi), in qualitative agreement with theories. We proposed a simple mechanism for this shear-induced migration based on hydrodynamic interaction (HI) between the surface and polymer chains. We find that the thickness of depletion layer of lambda-phage DNA molecules is about 10mum at Wi = 10.3, which is thinner than in the predictions for the FENE-P dumbbell model [Ma and Graham (2005)] and in Brownian dynamics simulations. The discrepancies suggest that current theoretical models of the polymer migration phenomenon are incomplete. We find that the time scale of DNA migration is on the order of the diffusion time over the distance of depletion layer, and that the mean fractional stretch of DNA molecules decreases near the surface over this same time scale. Experiments with deliberately fragmented DNA indicate that the decrease in mean fractional stretch near the surface might be caused by the selective retention of fragments in the DNA solution owing to weaker HI effects between the surface and shorter polymer chains. The shear-induced migration of DNA molecules exists in diminished form up to 3.0 c* (c* is the overlap concentration), implying that: in the traditionally defined dilute regime (c < c*), screening of wall hydrodynamics occurs over DNA concentration from 0.1 c* to 1.0 c*; and in the semidilute regime (c > c*); while the chains are

  13. Self-assembly of nonionic surfactant Tween 20@2β-CD inclusion complexes in dilute solution.

    PubMed

    Zhou, Chengcheng; Cheng, Xinhao; Zhao, Qiang; Yan, Yun; Wang, Jide; Huang, Jianbin

    2013-10-29

    It has long been considered that the addition of cyclodextrins (CDs) disfavors the self-assembly of surfactants in dilute solutions since the hydrophobic effect is destroyed upon the formation of the hydrophiphilic CD/surfactant inclusion complex. However, in this work, we found that β-CD/nonionic surfactant inclusion complexes are able to self-assemble into vesicles in dilute solutions, namely in solutions with concentration lower than the CMC of surfactants. When using Tween 20 as a model surfactant, HNMR and MS measurements indicate that the building block for the vesicles is the channel type Tween 20@2β-CD inclusion complex. Structure and IR analysis suggests that the self-assembly of hydrophilic Tween 20@2β-CD is driven by H-bonds between both the headgroup of Tween 20 and the hydroxyl groups of β-CD. The self-assembly of the inclusion complex between the β-CD and the nonionic surfactant in dilute solution is found to be a general phenomenon. Undoubtedly, surfactant@2β-CD inclusion complex can be a novel building block for nonamphiphilic self-assembly, which provides a new physical insight for the influence of cyclodextrins on the self-assembly of surfactants.

  14. 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.

  15. Removal of Cu{sup 2+}, Cd{sup 2+} and Mn(VII) from dilute, aqueous solutions by oxidized bituminous coal

    SciTech Connect

    Bodine, D.L.; Doyle, F.M.

    1995-07-01

    The ability of oxidized Upper Freeport bituminous coal to adsorb Cu{sup 2+}, Cd{sup 2+} and MN(VII) from very dilute aqueous solutions has been studied. Low-rank coal is known to adsorb heavy metal ions from dilute, aqueous solutions, probably by ion exchange and/or chelation by acidic functional groups on the coal surface. However, it would be advantageous to use higher rank coals for water treatment. Coal samples were oxidized thermally or by 30% H{sub 2}O{sub 2} to increase the surface concentration of phenolic and carboxylic groups, then portions were shaken with Cu{sup 2+} and Cd{sup 2+} solutions. Acidic KMnO{sub 4} was also used to oxidize coal, with concurrent sorption of the resulting MN(IV) and Mn(II). The effect of oxidation treatment, metal ion concentration, and solution pH on metal uptake kinetics was investigated. Potential applications for treating effluents, especially those containing oxidizing ions, are discussed, along with possible flowsheet options.

  16. Recovery of glycols, sugars, and Related Multiple -OH Compounds from Dilute-Aqueous Solution by Regenerable Adsorption onto Activated Carbons

    SciTech Connect

    Chinn, Daniel

    1999-06-01

    The present research explores the use of adsorption onto activated carbons as a means of recover glycerol, glycols, and sugars from dilute-aqueous solution. Our work is focused on understanding the mechanisms of adsorption onto carbons, assessing the degree of adsorption reversibility with precision, and implementing a bench-scale recovery process that results in a higher product concentration and reduction of the energy load for final purification.

  17. 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.

  18. 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.

  19. Protein–Protein Interactions in Dilute to Concentrated Solutions: α-Chymotrypsinogen in Acidic Conditions

    PubMed Central

    2015-01-01

    Protein–protein interactions were investigated for α-chymotrypsinogen by static and dynamic light scattering (SLS and DLS, respectively), as well as small-angle neutron scattering (SANS), as a function of protein and salt concentration at acidic conditions. Net protein–protein interactions were probed via the Kirkwood–Buff integral G22 and the static structure factor S(q) from SLS and SANS data. G22 was obtained by regressing the Rayleigh ratio versus protein concentration with a local Taylor series approach, which does not require one to assume the underlying form or nature of intermolecular interactions. In addition, G22 and S(q) were further analyzed by traditional methods involving fits to effective interaction potentials. Although the fitted model parameters were not always physically realistic, the numerical values for G22 and S(q → 0) were in good agreement from SLS and SANS as a function of protein concentration. In the dilute regime, fitted G22 values agreed with those obtained via the osmotic second virial coefficient B22 and showed that electrostatic interactions are the dominant contribution for colloidal interactions in α-chymotrypsinogen solutions. However, as protein concentration increases, the strength of protein–protein interactions decreases, with a more pronounced decrease at low salt concentrations. The results are consistent with an effective “crowding” or excluded volume contribution to G22 due to the long-ranged electrostatic repulsions that are prominent even at the moderate range of protein concentrations used here (<40 g/L). These apparent crowding effects were confirmed and quantified by assessing the hydrodynamic factor H(q → 0), which is obtained by combining measurements of the collective diffusion coefficient from DLS data with measurements of S(q → 0). H(q → 0) was significantly less than that for a corresponding hard-sphere system and showed that hydrodynamic nonidealities can lead to qualitatively incorrect

  20. Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water

    NASA Astrophysics Data System (ADS)

    Biswas, Rajib; Carpenter, William; Voth, Gregory A.; Tokmakoff, Andrei

    2016-10-01

    Infrared (IR) spectroscopy of the water O-H stretch has been widely used to probe both the local hydrogen-bonding structure and dynamics of aqueous systems. Although of significant interest, the IR spectroscopy of excess protons in water remains difficult to assign as a result of extensive and strong intermolecular interactions in hydrated proton complexes. As an alternate approach, we develop a mixed quantum-classical model for the vibrational spectroscopy of the excess proton in isotopically dilute water that draws on frozen proton-water clusters taken from reactive molecular dynamics trajectories of the latest generation multi-state empirical valence bond proton model (MS-EVB 3.2). A semi-empirical single oscillator spectroscopic map for the instantaneous transition frequency and transition dipole moment is constructed using potential energy surfaces for the O-H stretch coordinate of the excess proton using electronic structure calculations. Calculated spectra are compared with experimental spectra of dilute H+ in D2O obtained from double-difference FTIR to demonstrate the validity of the map. The model is also used to decompose IR spectra into contributions from different aqueous proton configurations. We find that the O-H transition frequency continuously decreases as the oxygen-oxygen length for a special pair proton decreases, shifting from Eigen- to Zundel-like configurations. The same shift is accompanied by a shift of the flanking water stretches of the Zundel complex to higher frequency than the hydronium O-H vibrations.

  1. Groundwater Infiltration Potential (GWIP) as an aid to determining the cause of dilution of waste water

    NASA Astrophysics Data System (ADS)

    Dirckx, Geert; Van Daele, Sofie; Hellinck, Nathan

    2016-11-01

    Groundwater infiltration through leaking sewers represents a considerable fraction of the total amount of wastewater dilution. In search for an easy-to-determine yet acceptably accurate estimation of the likelihood of groundwater infiltration into leaking sewers, the parameter 'groundwater infiltration potential' or shortly GWIP was defined. GWIP expresses the extent to which groundwater infiltration could - in contrast to the inflow of surface water - be a cause of dilution of sewage. The GWIP is determined by a comparison between the elevation of the groundwater table with the position of the sewer conduits per geo-spatial aggregation level (GAL). This first order analysis compares sets of three representative figures of the groundwater table's elevation, i.e. the minimum, the maximum and the average level with sets of two representative values of the pipes' positions, i.e. average invert and soffit levels. A GWIP map can be set-up indicating per GAL a GWIP score that represents a generic evaluation of the common (i.e. most occurring or representative) situation regarding the presence of the groundwater table versus the elevations of the sewer system. In this way the GWIP map can assist in the determination of the overall most likely origin - either surface water or groundwater - of dilution per GAL. Eventually this facilitates strategic decisions regarding the search for particular locations of dilution, and subsequently for the selection of specific remediation measures. The methodology is developed on a local scale of Flanders, Belgium but is generic and therefore applicable to any other region provided that information on the elevation of the sewer system and groundwater table is available.

  2. Lithogenic vs Biogenic Stream Water Chemistry: Following the Solute Flush

    NASA Astrophysics Data System (ADS)

    Bain, D. J.; Anderson, S.; Bullen, T.; Fitzpatrick, J.; Schulz, M.; Vivit, D.; White, A.

    2005-12-01

    Mediterranean hydrologic systems are driven by strong intra-annual variation in precipitation. Summer drought is followed by a pronounced solute flush at the beginning of the wet season. Solutes accumulate near the soil surface during dry periods via evapoconcentration and dry deposition. In a set of nested watersheds draining the Santa Cruz, California marine terraces, a differentiation between shallow soil water with biogenic solutes (enriched via evapotranspiration and biologic nutrient cycling) and deep soil water with lithogenic solutes (imprinted by chemical weathering) allows interpretation of flow pathways to the stream. The shallow soil waters are more concentrated than deep soil waters at the beginning of the wet season. Stream chemistry is a mixture of lithogenic deep soil water and biogenic shallow soil water; we expect the lithogenic component to increase downstream. However, the composition of the water along a downstream transect shows no clear shift to lithogenic compositions downstream, especially in the early wet season. The lithogenic water influence may be minimal as most flow paths are lateral across a thick argillic horizon and rarely encounter lithogenic zones. However, the continued influence of biogenic solutes seems to result from movement of evapoconcentrated water through the flow system. Simultaneous collection of groundwater and soil water along the transect shows the slow movement of flushed solutes through the system. Soil waters generally are most concentrated during the first precipitation events and become increasingly diluted throughout the remainder of the wet season. Immediately following the flushing of shallow soils, a concentration peak is observed in perched groundwater near the drainage divide. A similar peak appears in perched groundwater sequentially downstream, finally appearing in groundwater near the base of the catchment after several months. This pattern of flushed solutes in perched groundwaters may result from the

  3. Multilayering of Surfactant Systems at the Air-Dilute Aqueous Solution Interface.

    PubMed

    Thomas, Robert K; Penfold, Jeffrey

    2015-07-14

    In the last 15 years there have been a number of observations of surfactants adsorbed at the air-water interface with structures more complicated than the expected single monolayer. These observations, mostly made by neutron or X-ray reflectivity, show structures varying from the usual monolayer to monolayer plus one or two additional bilayers to multilayer adsorption at the surface. These observations have been assembled in this article with a view to finding some common features between the very different systems and to relating them to aspects of the bulk solution phase behavior. It is argued that multilayering is primarily associated with wetting or prewetting of the air-water interface by phases in the bulk system, whose structures depend on an overall attractive force between the constituent units. Two such phases, whose formation is assumed to be partially driven by strong specific ion binding, are a concentrated lamellar phase that forms at low concentrations and a swollen lamellar phase that is not space-filling. Multilayering phenomena at the air-water interface then offer a delicate and easy means of studying the finer details of the incompletely understood attraction that leads to these two phases, as well as an interesting new means of self-assembling surface structures. In addition, multilayering is often associated with unusual wetting characteristics. Examples of systems discussed, and in some cases their bulk phase behavior, include surfactants with multivalent metal counterions, surfactants with oligomers and polymers, surfactant with hydrophobin, dichain surfactants, lung surfactant, and the unusual system of ethanolamine and stearic acid. Two situations where the air-water surface is deliberately held out of equilibrium are also assessed for features in common with the steady-state/equilibrium observations.

  4. Enthalpies of the dissolution and dilution of aqueous solutions of rubidium and cesium diclofenac at 293.15-318.15 K

    NASA Astrophysics Data System (ADS)

    Manin, N. G.; Perlovich, G. L.; Fini, A.

    2014-03-01

    Enthalpies of the dissolution and dilution of aqueous solutions of rubidium and cesium diclofenac (RbDC and CsDC) are measured at 293.15, 298.15, 308.15, and 318.15 K at concentrations of water of less than 0.1 mol/kg. The heat capacity of RbDC and CsDC crystal salts is determined. Changes in the thermodynamic properties of both a solution and its components vs. concentration and temperature is considered. An increase in the endothermicity of the dissolution of RbDC and CsDC with a rise in temperature is noted. It is shown that the dissolution of both RbDC and CsDC electrolytes in water is determined by the contribution from entropy. It is shown that in aqueous solutions of RbDC and CsDC, the degree of binding of water molecules is higher than in pure water at temperatures below 303.15 K.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Experimental testing of a liquid bipropellant rocket engine using nitrous oxide and ethanol diluted with water

    NASA Astrophysics Data System (ADS)

    Phillip, Jeff; Morales, Rudy; Youngblood, Stewart; Saul, W. Venner; Grubelich, Mark; Hargather, Michael

    2016-11-01

    A research scale liquid bipropellant rocket engine testing facility was constructed at New Mexico Tech to perform research with various propellants. The facility uses a modular engine design that allows for variation of nozzle geometry and injector configurations. Initial testing focused on pure nitrous oxide and ethanol propellants, operating in the range of 5.5-6.9 MPa (800-1000 psi) chamber pressure with approximately 667 N (150 lbf) thrust. The system is instrumented with sensors for temperature, pressure, and thrust. Experimentally found values for specific impulse are in the range of 250-260 s which match computational predictions. Exhaust flow visualization is performed using high speed schlieren imaging. The engine startup and steady state exhaust flow features are studied through these videos. Computational and experimental data are presented for a study of dilution of the ethanol-nitrous oxide propellants with water. The study has shown a significant drop in chamber temperature compared to a small drop in specific impulse with increasing water dilution.

  10. 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

  11. Dissipative particle dynamics simulation of depletion layer and polymer migration in micro- and nanochannels for dilute polymer solutions.

    PubMed

    Fedosov, Dmitry A; Em Karniadakis, George; Caswell, Bruce

    2008-04-14

    The flows of dilute polymer solutions in micro- and nanoscale channels are of both fundamental and practical importance in variety of applications in which the channel gap is of the same order as the size of the suspended particles or macromolecules. In such systems depletion layers are observed near solid-fluid interfaces, even in equilibrium, and the imposition of flow results in further cross-stream migration of the particles. In this work we employ dissipative particle dynamics to study depletion and migration in dilute polymer solutions in channels several times larger than the radius of gyration (Rg) of bead-spring chains. We compare depletion layers for different chain models and levels of chain representation, solvent quality, and relative wall-solvent-polymer interactions. By suitable scaling the simulated depletion layers compare well with the asymptotic lattice theory solution of depletion near a repulsive wall. In Poiseuille flow, polymer migration across the streamlines increases with the Peclet and the Reynolds number until the center-of-mass distribution develops two symmetric off-center peaks which identify the preferred chain positions across the channel. These appear to be governed by the balance of wall-chain repulsive interactions and an off-center driving force of the type known as the Segre-Silberberg effect.

  12. 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.

  13. 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.

  14. ``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.

  15. 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).

  16. Some characteristics of pervaporation for dilute ethanol-water mixtures by alcohol-permselective composite membrane

    SciTech Connect

    Xiaohe Li; Shichang Wang

    1996-12-01

    Zeolite-filled polydimethylsiloxane/polysulfone composite membranes were prepared and used to separate ethanol from dilute ethanol-water mixtures through a pervaporation process. During this process the relationship between flux (J) and temperature (T) is J = 597.95 exp(-E{sub o}/RT)(g/m{sup 2}{center_dot}h), E{sub o} = 3.292 kJ/mol. The experimental results show that the flux decreases with increasing downstream pressure while the selectivity ({alpha}{sub EtOH/Water}) rises, the flux increases, and the selectivity decreases with a rise of feed concentration, and the flux as well as the selectivity increase with increasing bulk velocity on the upstream side of the membrane.

  17. 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).

  18. 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.

  19. Hydrogen bonding at the water surface revealed by isotopic dilution spectroscopy.

    PubMed

    Stiopkin, Igor V; Weeraman, Champika; Pieniazek, Piotr A; Shalhout, Fadel Y; Skinner, James L; Benderskii, Alexander V

    2011-06-08

    The air-water interface is perhaps the most common liquid interface. It covers more than 70 per cent of the Earth's surface and strongly affects atmospheric, aerosol and environmental chemistry. The air-water interface has also attracted much interest as a model system that allows rigorous tests of theory, with one fundamental question being just how thin it is. Theoretical studies have suggested a surprisingly short 'healing length' of about 3 ångströms (1 Å = 0.1 nm), with the bulk-phase properties of water recovered within the top few monolayers. However, direct experimental evidence has been elusive owing to the difficulty of depth-profiling the liquid surface on the ångström scale. Most physical, chemical and biological properties of water, such as viscosity, solvation, wetting and the hydrophobic effect, are determined by its hydrogen-bond network. This can be probed by observing the lineshape of the OH-stretch mode, the frequency shift of which is related to the hydrogen-bond strength. Here we report a combined experimental and theoretical study of the air-water interface using surface-selective heterodyne-detected vibrational sum frequency spectroscopy to focus on the 'free OD' transition found only in the topmost water layer. By using deuterated water and isotopic dilution to reveal the vibrational coupling mechanism, we find that the free OD stretch is affected only by intramolecular coupling to the stretching of the other OD group on the same molecule. The other OD stretch frequency indicates the strength of one of the first hydrogen bonds encountered at the surface; this is the donor hydrogen bond of the water molecule straddling the interface, which we find to be only slightly weaker than bulk-phase water hydrogen bonds. We infer from this observation a remarkably fast onset of bulk-phase behaviour on crossing from the air into the water phase.

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

    PubMed

    Suzuki, Yoshiharu; Mishima, Osamu

    2016-07-14

    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.

  1. 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.

  2. 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.

  3. Correlation and prediction of thermodynamic properties of nonelectrolytes at infinite dilution in water over very wide temperature and pressure ranges (2000 K and 10 GPa)

    NASA Astrophysics Data System (ADS)

    Plyasunov, Andrey V.

    2015-11-01

    Thermodynamic modeling of natural processes involving deep aqueous fluids requires the knowledge of the values of chemical potentials (the Gibbs energy) of aqueous species. An accurate prediction of thermodynamic properties at high T and P is a strong challenge. It is shown that geochemical models, including the well-known HKF-model, cannot be recommended for an indiscriminate use at supercritical temperatures to predict chemical potentials of nonelectrolytes at infinite dilution in water. Nevertheless, sufficiently accurate predictions of ϕ2∞ (the fugacity coefficients at infinite dilution in water) of aqueous nonelectrolytes up to 2000 K and water densities up to 1500 kg m-3, i.e. pressure up to 10-12 GPa, can be made relying on known theoretical relations valid at various parts of the phase diagram of water. In essence, the method, proposed in this work, consists in the interpolation of properties between two known limits: the first one, at low water densities, is defined by the values of the second virial coefficients for water-solute interactions, and the second, at high water densities - by predictions of the theory of a mixture of hard spheres. The interpolation at moderate temperatures (700-1300 K) and water densities (500-900 kg m-3) is simplified by sufficiently accurate predictions of properties using a semiempirical variant of a corresponding-states principle. Presented examples of the prediction of fugacity coefficients of "gases" at infinite dilution in water and of an aqueous solubility of corundum over very wide ranges of water densities/pressures demonstrate the potential and generality of the proposed methods of evaluating the thermodynamic properties of aqueous neutral compounds.

  4. 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.

  5. Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methyl-imidazolium nitrate.

    PubMed

    Sobota, Marek; Dohnal, Vladimír; Vrbka, Pavel

    2009-04-02

    Infinite dilution activity coefficients gamma(1)(infinity) and gas-liquid partition coefficients K(L) of 30 selected hydrocarbons, alcohols, ketones, ethers, esters, haloalkanes, nitrogen- and sulfur-containing compounds in the ionic liquid (IL) 1-ethyl-3-methylimidazolium nitrate [EMIM][NO(3)] were determined by gas-liquid chromatography at five temperatures in the range from 318.15 to 353.15 K. Relative contribution of adsorption at gas-liquid interphase to the overall solute retention, as examined by varying sample size and IL loading in the column, was found negligible. Partial molar excess enthalpies and entropies at infinite dilution were derived from the temperature dependence of the gamma(1)(infinity) values. The linear free energy relationship (LFER) solvation model was used to correlate successfully the KL values. The LFER correlation parameters and excess thermodynamic functions were analyzed to disclose molecular interactions operating between the IL and the individual solutes. In addition, the promising potential of [EMIM][NO(3)] for applications in solvent-aided separation processes was identified, the selectivities of [EMIM][NO(3)] for separation of aromatic hydrocarbons and thiophene from saturated hydrocarbons ranking among the highest ever observed with ILs or molecular solvents.

  6. Using temperature-programmed reaction for kinetic analysis of reactions in dilute aqueous solutions at high pressure

    SciTech Connect

    Brown, L.F.; Robinson, B.A.

    1986-01-01

    The technique of temperature-programmed reaction (TPR) is shown to be a practical experimental method for determining reaction-rate expressions and kinetics parameters for reactions in dilute aqueous solutions under high ambient pressure. By sampling and measuring the extent of reaction during a rise in temperature, information normally obtained from a series of isothermal batch kinetics experiments can be found in a single TPR test. The use of nonlinear least-squares regression eliminates the need to achieve a constant rate of temperature rise, simplifies the experimental requirements for TPR results, and gives more accurate answers than does a linear analysis of TPR results. Numerical simulations of TPR tests in the presence of random concentration-measurement error is used to assess the accuracy of the technique and to identify the best values of crucial operating parameters. The results of two TPR experiments measuring the alkaline hydrolysis of ethyl acetate demonstrate the applicability of the technique to reactions in dilute aqueous solutions at high pressure. These preliminary experimental results, along with numerical simulations, allow us to chart a course for future TPR kinetics experiments on a large number of similar reactions. 16 refs., 6 figs., 8 tabs.

  7. Highly charged ions in a dilute plasma: an exact asymptotic solution involving strong coupling.

    PubMed

    Brown, Lowell S; Dooling, David C; Preston, Dean L

    2006-05-01

    The ion sphere model introduced long ago by Salpeter is placed in a rigorous theoretical setting. The leading corrections to this model for very highly charged but dilute ions in thermal equilibrium with a weakly coupled, one-component background plasma are explicitly computed, and the subleading corrections shown to be negligibly small. This is done using the effective field theory methods advocated by Brown and Yaffe. Thus, corrections to nuclear reaction rates that such highly charged ions may undergo can be computed precisely. Moreover, their contribution to the equation of state can also be computed with precision. Such analytic results for very strong coupling are rarely available, and they can serve as benchmarks for testing computer models in this limit.

  8. Biomathematical modeling for diluted drugs.

    PubMed

    Chattopadhyay, S

    2003-07-01

    Several workers have proven that succussed ultra high dilution of a drug molecule in water or alcoholic medium, even exceeding Avogadro number, can bring forth noticeable physiological changes of an organism. Homeopathic drugs are prepared by dissolving such drug ingredients in distilled water and then the solution is centesimally diluted serially by ethanol. A mathematical model has been proposed by the present worker, which explains why the drug does not become non-molecular even in ultra-high dilution. This is due to loss of homogeneity in the solution, caused by increase of dielectric constant of the medium during the process of potentization. Facilitated binding of the drug molecules with minute physiologically important protein factors may be the cause of visible physiological alterations.

  9. On the internal field correction in far-infrared absorption of highly polar molecules in neat liquids and dilute solutions

    NASA Astrophysics Data System (ADS)

    Vij, J. K.; Kalmykov, Yu P.

    1993-08-01

    Far-infrared absorption spectra for liquid acetone, methylene chloride, acetonitrile, methyl iodide, and their dilute solutions in cyclohexane at 20 °C are measured by molecular laser spectrometer. Measurements of dielectric loss of polar liquids and solutions in the frequency range 2-300 GHz are made using a number of different techniques. These two sets of measurements are combined with those made using a Fourier transform spectrometer in order to cover the frequency range up to 250 cm-1 and total integrated absorption intensities are calculated. It is shown that the discrepancy between experimental integrated absorption and the theoretical results given by Gordon's sum rule with the Polo-Wilson internal field factor can be explained in the context of Bossis' theory. This theory gives a better agreement with the experimental integrated absorption intensity for these liquids.

  10. Dynamic light scattering studies on charged rod-like fd-virus in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Schulz, Susanne F.; Maier, Erich E.; Krause, Rainer; Hagenbüchle, Martin; Deggelmann, Martin; Weber, Reinhart

    1990-06-01

    Time correlation functions of the scattered light intensity are studied in aqueous solutions of charged rod-like fd-virus (L=880 nm, d=6 nm) at various ionic strengths. The short time behavior of the correlation function is dominated by the static structure factor S(q) which is also independently determined from static light scattering experiments. Comparison of correlation functions of solutions with high ionic strength (screened Coulomb interaction) and those of solutions with liquid-like nearest neighbor order (strong Coulomb interaction) shows different single particle diffusion coefficients on medium time scales at high scattering vectors, where mainly single particle properties are observed by light scattering. The single particle diffusion coefficient decreases with increasing structure peak height of the solutions. At low scattering vectors an extra slow mode component of the correlation function is observed for solutions with Coulomb interaction.

  11. Quantification of four artificial sweeteners in Finnish surface waters with isotope-dilution mass spectrometry.

    PubMed

    Perkola, Noora; Sainio, Pirjo

    2014-01-01

    The artificial sweeteners sucralose (SCL), acesulfame (ACS), saccharin (SAC), and cyclamate (CYC) have been detected in environmental waters in Europe and North America. Higher environmental levels are expected in view of the increasing consumption of these food additives. In this study, an isotope-dilution mass spectrometry (IDMS) LC-MS/MS method was developed and validated for quantifying the four artificial sweeteners in boreal lakes (n = 3) and rivers (n = 12). The highest concentrations of ACS, SAC, CYC and SCL were 9,600, 490, 210 and 1000 ng/L, respectively. ACS and SAC were detected in all studied samples, and CYC and SCL in 98% and 56% of the samples. Seasonal trends of ACS and SAC were observed in some rivers. ACS and SCL concentrations in rivers correlated linearly with population equivalents of the wastewater treatment plants in the catchment areas, whereas SAC and CYC concentrations depend more on the source.

  12. 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…

  13. Changes of water solution properties under the processes of their ultrasonic atomization

    NASA Astrophysics Data System (ADS)

    Akopyan, V. B.; Bambura, M. V.; Davidov, E. R.; Stupin, A. Yu.; Chubatova, O. I.

    2009-10-01

    Transformation of diluted water solutions of medicines into medicinal aerosols in ultrasonic inhalers leads to variation of concentration ratios for solution components in an aerosol and appearance of new substances synthesized usually in the process of cavitation in water solutions. It is demonstrated that for the characteristic concentrations of solution components intended for aerosol therapy the effect of concentration of its surface-active components is most significant in the process of ultrasonic dispersion into an aerosol. This effect must be taken into account in medical practice.

  14. 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.

  15. Proteomic characterization of IgY preparations purified with a water dilution method.

    PubMed

    Nilsson, Elin; Hanrieder, Jörg; Bergquist, Jonas; Larsson, Anders

    2008-12-24

    Antigen-specific chicken IgY antibodies have been used for oral immunotherapy as an alternative or complement to antibiotics in several studies. The water dilution (WD) method has several advantages for purifying IgY. It is rapid, efficient, suitable for large-scale production, and nothing but water is added. The water-soluble fraction contains other proteins and lipids besides IgY. The protein content was characterized by two-dimensional gel electrophoresis (2DGE) and nanoflow liquid chromatography coupled offline to matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (nanoLC-MALDI TOF/TOF MS). Protein analysis was complicated due to the large dynamic concentration range, but 26 proteins could be identified. The relative protein concentrations in different batches were very similar according to protein patterns on 1D gels and protein concentration determinations. Thus, the purification method has a high reproducibility. The concentrations of cholesterols and triglycerides were low and should not have an effect on the plasma levels of treated patients. Purification of IgY for oral use with WD is therefore a recommended method.

  16. Physical mechanisms for the offshore detachment of the Changjiang Diluted Water in the East China Sea

    NASA Astrophysics Data System (ADS)

    Chen, Changsheng; Xue, Pengfei; Ding, Pingxing; Beardsley, R. C.; Xu, Qichun; Mao, Xianmou; Gao, Guoping; Qi, Jiahua; Li, Chunyan; Lin, Huichan; Cowles, Geoffrey; Shi, Maochong

    2008-02-01

    Physical mechanisms for the summertime offshore detachment of the Changjiang Diluted Water (CDW) into the East China Sea are examined using the high-resolution, unstructured-grid, Finite-Volume Coastal Ocean Model (FVCOM). The model results suggest that isolated low salinity water lens detected west of Cheju Island can be formed by (1) a large-scale adjustment of the flow field to the Changjiang discharge and (2) the detachment of anticyclonic eddies as a result of baroclinic instability of the CDW front. Adding the Changjiang discharge intensifies the clockwise vorticity of the subsurface current (originating from the Taiwan Warm Current) flowing along the 50-m isobath and thus drives the low-salinity water in the northern coastal area of the Changjiang mouth offshore over a submerged plateau that extends toward Cheju Island. Given a model horizontal resolution of less than 1.0 km, the CDW front becomes baroclinically unstable and forms a chain of anticyclonic and cyclonic eddies. The offshore detachment of anticyclonic eddies can carry the CDW offshore. This process is enhanced under northward winds as a result of the spatially nonuniform interaction of wind-induced Ekman flow and eddy-generated frontal density currents. Characteristics of the model-predicted eddy field are consistent with previous theoretical studies of baroclinic instability of buoyancy-driven coastal density currents and existing satellite imagery. The plume stability is controlled by the horizontal Ekman number. In the Changjiang, this number is much smaller than the criterion suggested by a theoretical analysis.

  17. A method for measuring enthalpy of volatilization of a compound, Delta(vol)H, from dilute aqueous solution.

    PubMed

    Wang, Tianshu

    2006-01-01

    This study has developed a method for measuring the enthalpy of volatilization (Delta(vol)H) of a compound in a dilute solution via ion-molecule reactions and gas-phase analysis using selected ion flow tube mass spectrometry (SIFT-MS). The Delta(vol)H/R value was obtained using an equation with three variant forms either from the headspace concentration of the solution or from individual product ion(s). Under certain experimental conditions, the equation has the simplest form [formula: see text], where R is the gas constant (8.314 J . mol(-1) . K(-1)), i(n) and I are the respective product and precursor ion count rates, and T is the temperature of the solution. As an example, a series of 27.0 micromol/L aqueous solutions of acetone was analyzed over a temperature range of 25-50 degrees C at 5 degrees C intervals using H3O+, NO+ and O2+* precursor ions, producing a mean Delta(vol)H/R value of 4700 +/- 200 K. This corresponds with current literature values and supports the consistency of the new method. Notably, using this method, as long as the concentration of the solution falls into the range of Henry's law, the exact concentration does not have to be known and it can require only one sample at each temperature. Compared with previous methods which involve the measurement of Henry's law constant at each temperature, this method significantly reduces the number of samples required and avoids the labour and difficulties in preparing standard solutions at very low concentrations. Further to this, if the contents of a solution were unknown the measured Delta(vol)H/R from individual product ion(s) can help to identify the origin of the ion(s).

  18. Ionic regulation in aglomerular tropical estuarine pufferfishes submitted to sea water dilution.

    PubMed

    Prodocimo, V; Freire, C A.

    2001-07-30

    Two common tropical estuarine pufferfishes were used in this study. The main species was Sphoeroides testudineus Linnaeus, 1758, a very abundant species in the estuaries of Paranaguá Bay (Paraná, Brazil), found in waters of salinity between 0 per thousand (tidal creeks) and 34 per thousand (tidal plains). The second species was S. greeleyi Gilbert, 1900, a species limited in distribution to an area of higher salinity ( approximately 30 per thousand) than S. testudineus. The present work thus aimed at evaluating the capacity of ionic regulation of both species of pufferfishes when submitted to salinity decrease, relating the results with both species' distribution in nature. Ion regulation curves for sodium (Na(+)), chloride (Cl(-)), and magnesium (Mg(2+)) ions after 6 h and 15 days of exposure of the abundant S. testudineus to the salinities of 30 per thousand, 20 per thousand, 10 per thousand, and 5 per thousand were elaborated, as well as for Cl(-) and Mg(2+) after 6 h and 15 days of exposure of both species to the extreme salinities of 35 per thousand and 5 per thousand. Both species kept their plasma Cl(-) ( approximately 120-160 mM), and Mg(2+) ( approximately 1.3 mM) concentrations stable, as did S. testudineus for Na(+) ( approximately 130 mM). Na(+) (measured only for S. testudineus) and Cl(-) were either hyper-regulated (in 5 per thousand) or kept iso-ionic ( approximately 7-10 per thousand), but more often hypo-regulated (20-35 per thousand). In contrast, Mg(2+) was strongly hypo-regulated in all salinities. According to their distribution records in nature, S. greeleyi was less able to tolerate strong sea water dilution, showing mortality after 5 days in 5 per thousand water. These estuarine pufferfishes are thus efficient regulators of plasma ionic concentrations in diluted sea water, as expected from their occupation of estuaries. The experiments have supported the distribution records of both species in the estuarine complex and resident estuarine

  19. 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.

  20. 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

  1. Nanogel formation from dilute solutions of clickable elastin-like recombinamers and its dependence on temperature: two fractal gelation modes.

    PubMed

    González de Torre, Israel; Quintanilla, Luis; Pinedo-Martín, Guillermo; Alonso, Matilde; Rodríguez-Cabello, José Carlos

    2014-08-27

    Diluted, complementary, click-reactive elastin-like recombinamer (ELR) solutions have been prepared and mixed at two different temperatures, one below and one above the characteristic transition temperature (Tt) of these chemically modified ELRs. FTIR measurements, size, aspect ratio, zeta potential, and microrheological measurements have been carried out on the nanostructures formed under these dilute conditions as a way to better understand the relationship between the final macroscopic properties of ELR-based hydrogels and the molecular conditions governing the initial stages of the chemical cross-linking process that occurs, especially its dependence on the preparation temperature relative to Tt. As a result, two different fractal modes of gel formation have been found at the two temperatures studied (above and below Tt). Thus, when the reaction mixture is prepared below Tt, essentially one-dimensional linear nanogels with a high aspect ratio are obtained. In contrast, 3D nanogels are formed above Tt, with spherical shapes predominating. These different structures seem to reflect the two molecular organizations of the single components of the mixture under these conditions, namely extended chains below Tt and a spherical arrangement above Tt. In addition to the interest in these nanogels as models for understanding the formation of microscopic structures and differential macroscopic properties under more conventional hydrogel-formation conditions, these nanogels are of interest because of their thermoresponsiveness and biocompatibility, which provide them with potential uses for drug delivery and other biomedical applications in living systems.

  2. 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...

  3. Bioelectrochemical recovery of Cu, Pb, Cd, and Zn from dilute solutions.

    PubMed

    Modin, Oskar; Wang, Xiaofei; Wu, Xue; Rauch, Sebastien; Fedje, Karin Karlfeldt

    2012-10-15

    In a microbial bioelectrochemical system (BES) living microorganisms catalyze the anodic oxidation of organic matter at a low anode potential. We used a BES with a biological anode to power the cathodic recovery of Cu, Pb, Cd, and Zn from a simulated municipal solid waste incineration ash leachate. By varying the control of the BES, the four metals could sequentially be recovered from a mixed solution by reduction on a titanium cathode. First, the cell voltage was controlled at zero, which allowed recovery of Cu from the solution without an electrical energy input. Second, the cathode potential was controlled at -0.51 V to recover Pb, which required an applied voltage of about 0.34 V. Third, the cathode potential was controlled at -0.66 V to recover Cd, which required an applied voltage of 0.51 V. Finally, Zn was the only metal remaining in solution and was recovered by controlling the anode at +0.2V to maximize the generated current. The study is the first to demonstrate that a BES can be used for cathodic recovery of metals from a mixed solution, which potentially could be used not only for ash leachates but also for e.g. metallurgical wastewaters and landfill leachates.

  4. Mechanism of Pitting Corrosion Prevention by Nitrite in Carbon Steel Exposed to Dilute Salt Solutions

    SciTech Connect

    Zapp, P.E.

    2002-05-02

    The overall goal of this project was to develop a detailed understanding of the role of nitrite in preventing the breakdown of protective oxide on steel and on the onset of pitting, by considering the interactions of the oxidation and reduction reactions that may occur in alkaline salt solutions.

  5. 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+.

  6. 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

  7. Mechanism of Pitting Corrosion Prevention by Nitrite in Carbon Steel Exposed to Dilute Salt Solutions

    SciTech Connect

    Philip E. Zapp; John W. Van Zee

    2002-02-01

    The research has developed a broad fundamental understanding of the inhibition action of nitrite ions in preventing nitrate pitting corrosion of carbon steel tanks containing high-level radioactive waste. This fundamental understanding can be applied to specific situations during waste removal for permanent disposition and waste tank closure to ensure that the tanks are maintained safely. The results of the research provide the insight necessary to develop solutions that prevent further degradation.

  8. The Interaction of Polycrystalline Copper Films with Dilute Aqueous Solutions of Cupric Chloride

    DTIC Science & Technology

    1989-10-01

    in atmosphere has always been of interest because of the extensive use of copper and brass in buildings and statues, for example. A study by Pinnel et...solution and the sample surface layer have been reported with no mention of the microstructure of the copper sample except for a few cases where chemical...used as a substrate when the deposited film will be removed for mechanical testing. In this case , the copper film was removed prior to characterization

  9. 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.

  10. Conversion of borate-based glass scaffold to hydroxyapatite in a dilute phosphate solution.

    PubMed

    Liu, Xin; Pan, Haobo; Fu, Hailuo; Fu, Qiang; Rahaman, Mohamed N; Huang, Wenhai

    2010-02-01

    Porous scaffolds of a borate-based glass (composition in mol%: 6Na2O, 8K2O, 8MgO, 22CaO, 36B2O3, 18SiO2, 2P2O5), with interconnected porosity of approximately 70% and pores of size 200-500 microm, were prepared by a polymer foam replication technique. The degradation of the scaffolds and conversion to a hydroxyapatite-type material in a 0.02 M K2HPO4 solution (starting pH = 7.0) at 37 degrees C were studied by measuring the weight loss of the scaffolds, as well as the pH and the boron concentration of the solution. X-ray diffraction, scanning electronic microscopy and energy dispersive x-ray analysis showed that a hydroxyapatite-type material was formed on the glass surface within 7 days of immersion in the phosphate solution. Cellular response to the scaffolds was assessed using murine MLO-A5 cells, an osteogenic cell line. Scanning electron microscopy showed that the scaffolds supported cell attachment and proliferation during the 6 day incubation. The results indicate that this borate-based glass could provide a promising degradable scaffold material for bone tissue engineering applications.

  11. Vacancy trapping by solute atoms during quenching in Cu-based dilute alloys studied by positron annihilation spectroscopy

    NASA Astrophysics Data System (ADS)

    Yabuuchi, A.; Yamamoto, Y.; Ohira, J.; Sugita, K.; Mizuno, M.; Araki, H.; Shirai, Y.

    2009-11-01

    Frozen-in vacancies and the recovery have been investigated in some Cu-based dilute alloys by using positron annihilation lifetime spectroscopy. Cu-0.5at%Sb, Cu-0.5at%Sn and Cu-0.5at%In dilute bulk alloys were quenched to ice water from 1223 K. A pure-Cu specimen was also quenched from the same temperature. As a result, no frozen-in vacancies have been detected in as-quenched pure-Cu specimen. On the other hand, as-quenched Cu-0.5at%Sb alloy contained frozen-in thermal equilibrium vacancies with concentration of 3 × 10-5. Furthermore, these frozen-in vacancies in Cu-0.5at%Sb alloy were stable until 473 K, and began to migrate at 523 K. Finally, the Cu-Sb alloy were recovered to the fully annealed state at 823 K. This thermal stability clearly implies some interaction exists between a vacancy and Sb atom and due to the interaction, thermal equilibrium vacancies are trapped by Sb atoms during quenching.

  12. 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.

    2011-09-16

    Dilution of aluminum discharged to reservoirs in filter-backwash effluents at water-treatment facilities in Massachusetts was investigated by a field study and computer simulation. Determination of dilution is needed so that permits for discharge ensure compliance with water-quality standards for aquatic life. The U.S. Environmental Protection Agency chronic standard for aluminum, 87 micrograms per liter (μg/L), rather than the acute standard, 750 μg/L, was used in this investigation because the time scales of chronic exposure (days) more nearly match rates of change in reservoir concentrations than do the time scales of acute exposure (hours).Whereas dilution factors are routinely computed for effluents discharged to streams solely on the basis of flow of the effluent and flow of the receiving stream, dilution determination for effluents discharged to reservoirs is more complex because (1), compared to streams, additional water is available for dilution in reservoirs during low flows as a result of reservoir flushing and storage during higher flows, and (2) aluminum removal in reservoirs occurs by aluminum sedimentation during the residence time of water in the reservoir. Possible resuspension of settled aluminum was not considered in this investigation. An additional concern for setting discharge standards is the substantial concentration of aluminum that can be naturally present in ambient surface waters, usually in association with dissolved organic carbon (DOC), which can bind aluminum and keep it in solution.A method for dilution determination was developed using a mass-balance equation for aluminum and considering sources of aluminum from groundwater, surface water, and filter-backwash effluents and losses caused by sedimentation, water withdrawal, and spill discharge from the reservoir. The method was applied to 13 reservoirs. Data on aluminum and DOC concentrations in reservoirs and influent water were collected during the fall of 2009. Complete

  13. Sorption of substituted indoles on highly cross-linked polystyrene from water-acetonitrile solutions

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Myakishev, A. A.; Il'Ina, E. A.; Il'in, M. M.; Davankov, V. A.; Bulanova, A. V.

    2011-07-01

    The sorption of first synthesized indole derivatives by highly cross-linked polystyrenes from water-acetonitrile solutions was studied by high-performance liquid chromatography. The retention factors and differences in the Gibbs energy of adsorption from infinite diluted solutions were calculated, and the applicability of the Snyder-Soczewinski and Scott-Kucera models for describing the chromatographic retention of sorbates on a polymer network of highly cross-linked polystyrene was shown.

  14. Experimental and Numerical Investigation of Boron Dilution Transients in Pressurized Water Reactors

    SciTech Connect

    Hertlein, Roland J.; Umminger, Klaus; Kliem, Soeren; Prasser, Horst-Michael; Hoehne, Thomas; Weiss, Frank-Peter

    2003-01-15

    Within the pressurized water reactor (PWR) safety analyses, attention has increasingly focused in recent years on boron dilution events that could potentially lead to reactivity transients. Mixing of the low-boron water with the ambient coolant of higher boron content provides an important mitigation mechanism before the low-boron water enters the core.Experimental support is needed to validate the computational tools to be applied to analyze the mixing of the low-boron water. Experiments were performed in the three test facilities - the Upper Plenum Test Facility (UPTF), the Primaerkreislauf (PKL), and the Rossendorf coolant mixing model (ROCOM) - in Germany.The relevant PKL and UPTF tests were focused on small-break loss-of-coolant accident (SBLOCA) scenarios with reflux-condenser mode and restart of natural circulation. The two test facilities represent a typical western-type PWR and are/were operated by Siemens/KWU now Framatome ANP in Germany. While the restart of natural circulation was investigated in the PKL system test facility (volume 1:145, height 1:1), the UPTF experiments dealt with the mixing of water flows with different boron concentration in the cold legs, reactor pressure vessel (RPV) downcomer, and the lower plenum (all these components were full-scale models).The results from the PKL test facility demonstrate that in case of a postulated SBLOCA with reflux condensation phase, natural circulation does not start up simultaneously in all loops. This means that slugs of condensate, which might have accumulated in the pump seal during reflux-condenser mode of operation, would reach the RPV at different points in time. The UPTF tests showed an almost ideal mixing of water flows with different boron concentration in the RPV downcomer.The ROCOM test facility has been built in a linear scale of 1:5 for the investigation of coolant mixing phenomena in a wide range of flow conditions in the RPV of the German KONVOI-type PWR. The test results presented are

  15. 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.

  16. 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.

  17. Radiation induced modification of tryptophan and tyrosine residues in flavocytochrome b 2 in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Bhattacharya, D.; Saha, A.; Mandal, P. C.

    2000-07-01

    Steady state gamma irradiation of an aqueous solution of flavocytochrome b 2 under different conditions led to modification of tryptophan and tyrosine residues. These aromatic amino acid residues were more susceptible to the attack by OH radicals than H atoms. Unchanged quantum yield values for tryptophan and tyrosine residues and unchanged tryptophan excited state lifetime in the irradiated enzyme suggests that irradiation results in breakage of some non-covalent bonds disrupting the peptide framework partially. It is justified by the circular dichroic studies for the irradiated enzyme which shows a reduced helicity but no evolution towards any other structures.

  18. 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.

  19. 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.

  20. 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).

  1. Kinetics of chain collapse in dilute polymer solutions: molecular weight and solvent dependences.

    PubMed

    Maki, Yasuyuki; Dobashi, Toshiaki; Nakata, Mitsuo

    2007-04-07

    The molecular weight and solvent dependences of the characteristic time of chain collapse were studied for poly(methyl methacrylate) (PMMA) of the molecular weight Mw=6.4x10(6) and 1.14x10(7) in pure acetonitrile (AcN) and in the mixed solvent of AcN+water (10 vol %). The size of PMMA chains was measured as a function of the time after the quench by static light scattering and the chain collapse processes were expressed by the plot of the expansion factor alpha2 vs ln t. The chain collapse in the mixed solvent AcN+water (10 vol %) was found to occur much faster than that in pure AcN, though the measurement of the former collapse process required several hours. In order to make a comparison between the rates of chain collapses, the fast chain collapse process was superposed on the slow one by scaling the time of the fast process as gammat. The scale factor gamma was determined by comparing the chain collapse processes of nearly the same equilibrium expansion factor with each other. Accordingly, the superposition of the collapse for Mw=6.4x10(6) on that for Mw=1.14x10(7) yielded gammam=4.0+/-0.6 for the process in AcN+water and 5.5+/-0.6 in AcN. The superposition of the chain collapse process in AcN+water on that in AcN yielded gammas=9.5+/-1.4 for Mw=6.4x10(6) and 12.0+/-1.8 for Mw=1.14x10(7). This analysis suggests that gammam and gammas are constant independent of each other. Thus, by assuming the molecular weight dependence of gammam approximately Mz, the characteristic time tauexp of chain collapse was conjectured as tauexp approximately kappaMz, where kappa reflects the nature of solvent species. The ratio of kappa for PMMA in AcN to that in AcN+water is given by gammas. The exponent was estimated to be z=2.4+/-0.7 for AcN+water and 3.0+/-0.7 for AcN. These values are compatible with the theoretical prediction z=3 based on a phenomenological model, though the observed characteristic times are longer by several orders of magnitude than those of the theoretical

  2. 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

  3. 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.

  4. Transport properties in dilute UN (X ) solid solutions (X =Xe ,Kr )

    NASA Astrophysics Data System (ADS)

    Claisse, Antoine; Schuler, Thomas; Lopes, Denise Adorno; Olsson, Pär

    2016-11-01

    Uranium nitride (UN) is a candidate fuel for current GEN III fission reactors, for which it is investigated as an accident-tolerant fuel, as well as for future GEN IV reactors. In this study, we investigate the kinetic properties of gas fission products (Xe and Kr) in UN. Binding and migration energies are obtained using density functional theory, with an added Hubbard correlation to model f electrons, and the occupation matrix control scheme to avoid metastable states. These energies are then used as input for the self-consistent mean field method which enables to determine transport coefficients for vacancy-mediated diffusion of Xe and Kr on the U sublattice. The magnetic ordering of the UN structure is explicitly taken into account, for both energetic and transport properties. Solute diffusivities are compared with experimental measurements and the effect of various parameters on the theoretical model is carefully investigated. We find that kinetic correlations are very strong in this system, and that despite atomic migration anisotropy, macroscopic solute diffusivities show limited anisotropy. Our model indicates that the discrepancy between experimental measurements probably results from different irradiation conditions, and hence different defect concentrations.

  5. 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.

  6. 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.

  7. Single chains of strong polyelectrolytes in aqueous solutions at extreme dilution: Conformation and counterion distribution

    NASA Astrophysics Data System (ADS)

    Xu, Guofeng; Luo, Shuangjiang; Yang, Qingbo; Yang, Jingfa; Zhao, Jiang

    2016-10-01

    The molecular conformation of two typical polyelectrolytes, sodium polystyrene sulfonate (NaPSS) and quarternized poly-4-vinylpyridine (QP4VP), was studied in aqueous solutions without salt addition at the single molecular level. By fluorescence correlation spectroscopy, the hydrodynamic radius (Rh) of NaPSS and QP4VP with the molecular weight ranging more than one order of magnitude was measured. The scaling analysis of Rh exhibits scaling exponent of 0.70 and 0.86 for NaPSS and QP4VP in solutions without added salts, respectively, showing the conformation is much more expanded than random coil. Numerical fittings using the model of diffusion of a rod molecule agree with the data well, indicating that the polyelectrolyte chains take the rod-like conformation under the condition without salt addition. Further investigations by determining the electric potential of single PSS- chains using the photon counting histogram technique demonstrate the enhanced counterion adsorption to the charged chain at higher molecular weight.

  8. 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.

  9. 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.

  10. Optimization of dilute acid pretreatment of water hyacinth biomass for enzymatic hydrolysis and ethanol production

    PubMed Central

    Idrees, Muhammad; Adnan, Ahmad; Sheikh, Shahzad; Qureshic, Fahim Ashraf

    2013-01-01

    The present study was conducted for the optimization of pretreatment process that was used for enzymatic hydrolysis of lignocellulosic biomass (Water Hyacinth, WH), which is a renewable resource for the production of bioethanol with decentralized availability. Response surface methodology has been employed for the optimization of temperature (oC), time (hr) and different concentrations of maleic acid (MA), sulfuric acid (SA) and phosphoric acid (PA) that seemed to be significant variables with P < 0.05. High F and R2 values and low P-value for hydrolysis yield indicated the model predictability. The pretreated biomass producing 39.96 g/l, 39.86 g/l and 37.9 g/l of reducing sugars during enzymatic hydrolysis with yield 79.93, 78.71 and 75.9 % from PA, MA and SA treated respectively. The order of catalytic effectiveness for hydrolysis yield was found to be phosphoric acid > maleic acid > sulfuric acid. Mixture of sugars was obtained during dilute acid pretreatment with glucose being the most prominent sugar while pure glucose was obtained during enzymatic hydrolysis. The resulting sugars, obtained during enzymatic hydrolysis were finally fermented to ethanol, with yield 0.484 g/g of reducing sugars which is 95 % of theoretical yield (0.51 g/g glucose) by using commercial baker's yeast (Sacchromyces cerveasiae). PMID:26417215

  11. Optimization of dilute acid pretreatment of water hyacinth biomass for enzymatic hydrolysis and ethanol production.

    PubMed

    Idrees, Muhammad; Adnan, Ahmad; Sheikh, Shahzad; Qureshic, Fahim Ashraf

    2013-01-01

    The present study was conducted for the optimization of pretreatment process that was used for enzymatic hydrolysis of lignocellulosic biomass (Water Hyacinth, WH), which is a renewable resource for the production of bioethanol with decentralized availability. Response surface methodology has been employed for the optimization of temperature ((o)C), time (hr) and different concentrations of maleic acid (MA), sulfuric acid (SA) and phosphoric acid (PA) that seemed to be significant variables with P < 0.05. High F and R (2) values and low P-value for hydrolysis yield indicated the model predictability. The pretreated biomass producing 39.96 g/l, 39.86 g/l and 37.9 g/l of reducing sugars during enzymatic hydrolysis with yield 79.93, 78.71 and 75.9 % from PA, MA and SA treated respectively. The order of catalytic effectiveness for hydrolysis yield was found to be phosphoric acid > maleic acid > sulfuric acid. Mixture of sugars was obtained during dilute acid pretreatment with glucose being the most prominent sugar while pure glucose was obtained during enzymatic hydrolysis. The resulting sugars, obtained during enzymatic hydrolysis were finally fermented to ethanol, with yield 0.484 g/g of reducing sugars which is 95 % of theoretical yield (0.51 g/g glucose) by using commercial baker's yeast (Sacchromyces cerveasiae).

  12. Kinetic study of empty fruit bunch using hot liquid water and dilute acid.

    PubMed

    Kim, Jun Seok; Choi, Won Il; Kang, Minsu; Park, Ji Yeon; Lee, Jin-Suk

    2012-07-01

    Empty fruit bunch (EFB), a residual product of the palm plantation, is an attractive biomass for biorefinery. As xylan is susceptible to high temperature pretreatment, it is important to setup a proper pretreatment condition to maximize the sugar recovery from EFB. Kinetic parameters of mathematical models were obtained in order to predict the concentration of xylose, glucose, furfural, and acetic acid in the hydrolysate and to find production conditions of xylose. We investigated the kinetics of hot liquid water and dilute sulfuric acid hydrolysis over a 40-min period using a self-designed setup by measuring the concentrations of released sugars (xylose, glucose) and degradation products (acetic acid and furfural). The reaction was performed within the range 160∼180 °C, under reaction conditions of various concentration of sulfuric acid (0.1∼0.2%) and 1:7 solid-liquid ratio in a batch reactor. The kinetic constants can be expressed by the Arrhenius equation with the activation energy for the hydrolysis of sugar and decomposition of sugar. The activation energy of xylose was determined to be 136.2187 kJ mol(-1).

  13. Effect of physical pretreatment on dilute acid hydrolysis of water hyacinth (Eichhornia crassipes).

    PubMed

    Harun, M Y; Dayang Radiah, A B; Zainal Abidin, Z; Yunus, R

    2011-04-01

    Effects of different physical pretreatments on water hyacinth for dilute acid hydrolysis process (121 ± 3 °C, 5% H(2)SO(4), 60 min) were comparatively investigated. Untreated sample had produced 24.69 mg sugar/g dry matter. Steaming (121 ± 3 °C) and boiling (100 ± 3 °C) for 30 min had provided 35.9% and 52.4% higher sugar yield than untreated sample, respectively. The highest sugar yield (132.96 mg sugar/g dry matter) in ultrasonication was obtained at 20 min irradiation using 100% power. The highest sugar production (155.13 mg sugar/g dry matter) was obtained from pulverized samples. Hydrolysis time was reduced when using samples pretreated by drying, mechanical comminution and ultrasonication. In most methods, prolonging the pretreatment period was ineffective and led to sugar degradations. Morphology inspection and thermal analysis had provided evidences of structure disruption that led to higher sugar recovery in hydrolysis process.

  14. Effect of added polymer in free jets of a dilute polymer solution

    NASA Astrophysics Data System (ADS)

    Renoult, Marie-Charlotte; Charpentier, Jean-Baptiste; Crumeyrolle, Olivier; Mutabazi, Innocent

    2016-11-01

    The instability of a free viscoelastic jet is experimentally investigated by extruding an aqueous solution containing five parts per million of Poly(ethylene oxide) into air from a sixty micrometers orifice at relative low speeds. A method of image analysis was developed to quantify the effect of the added polymer on the morphology and the stability of the jet breakup. Three main representations were considered: the area versus perimeter relation for all liquid objects detected on the images, i.e. jets and jet fragments, the equivalent diameter distribution of jet fragments and the standard deviation curve of jets profiles. The former two provide information on the morphology of jet fragments: distinction of two classes, products and residues, and existence of coalescence. The latter gives information on the jet breakup stability: measurement of the growth rate and initial amplitude of the jet instability and detection of beads-on-a-string structures in the jet interface deformation. Experimental results will be presented and compared to theory.

  15. 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

  16. The influence of temperature, sucrose and lactose on dilute solution properties of basil (Ocimumbasilicum) seed gum.

    PubMed

    Mirabolhassani, Seyed Elias; Rafe, Ali; Razavi, Seyed M A

    2016-12-01

    Hydrocolloid interactions with solvent/cosolutes play a vital role in the resolution of their functional properties. Basil seed gum (BSG) is a plant-derived hydrocolloid which has been found many applications in food formulations as stabilizer, emulsifier, thickener and gelling agents. Sucrose and lactose are the most effective sugars in textural and sensorial properties of bakery and dairy products which adding them to solutions containing hydrocolloids can be helpful to approach a proper formula. In this paper, the effect of temperature (25-65°C), sucrose (10, 20, 30 and 40%) and lactose (5, 10 and 15%) were investigated through some molecular parameters of BSG. Results revealed high flexible chain (665.35), intrinsic viscosity (11.38 dl/g) and hydrogel content (73%) of BSG, which may be attributed to some extent by its high molecular weight (1.73×10(6)Da). The density and intrinsic viscosity of BSG were diminished by growing temperature from 25 to 55°C. Among five models, which were applied to estimate intrinsic viscosity, Higiro-2 was the most suitable model at varying temperatures and cosolutes concentrations. The sugars showed a significant effect on the molecular parameters of BSG such as swollen specific volume, shape function, hydration parameter, and coil dimensions. The sugars showed more impact on the [η] of BSG and its molecular parameters than that of temperature. However, lactose had a more prominent effect on the BSG dimensions than that of sucrose, which can be related to its molecular conformation and spatial orientation. It is feasible to make a proper formula by BSG and explain some phenomena in its applications in food and pharmaceutical systems.

  17. 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.

  18. Concentration effects on turbulence in dilute polymer solutions far from walls.

    PubMed

    de Chaumont Quitry, Alexandre; Ouellette, Nicholas T

    2016-06-01

    We report measurements of the modification of turbulence far from any walls by small concentrations of long-chain polymers. We consider a range of statistical properties of the flow, including Eulerian and Lagrangian velocity structure functions, Eulerian acceleration correlation functions, and the relative dispersion of particle pairs. In all cases, we find that the polymer concentration has a strong effect on the extent to which the statistical properties are changed compared to their values in pure water. These effects can be captured by the recently proposed energy flux-balance model (when suitably extended into the time domain for Lagrangian statistics). However, unlike previous measurements, which found that the concentration effect could be completely scaled out, we consistently find that our data collapse onto two different master curves, one for small concentration and one for larger concentration. We suggest that the difference between the two may be related to the onset of interactions among polymer chains, which is likely to be more easily observed at the small Weissenberg numbers we consider here.

  19. Memory effect in the chain-collapse process in a dilute polymer solution

    NASA Astrophysics Data System (ADS)

    Maki, Yasuyuki; Sasaki, Naoki; Nakata, Mitsuo

    2004-12-01

    The effect of temperature perturbation on a single-chain-collapse process was studied for poly(methyl methacrylate) with the molecular weight Mw=1.05×107 in the mixed solvent of tert-butyl alcohol+water (2.5 vol %). In the chain-collapse process after a quench from the θ temperature to a temperature T1, the temperature was changed from T1 to T2 at the time t1 after the quench and returned to T1 at the time t1+t2. In the three stages at T1, T2, and T1, measurements of the mean-square radius of gyration of polymer chains were carried out by static light scattering and the chain-collapse process was represented by the expansion factor as a function of time. An effect of chain aggregation on the measurements was negligibly small because of the very slow phase separation. For the negative temperature perturbation (T1>T2), the chain-collapse processes observed in the first and third stages were connected smoothly and agreed with the collapse process due to a single-stage quench to T1. A memory of the chain collapse in the first stage at T1 was found to persist into the third stage at the same temperature T1 without being affected by the temperature perturbation of T2 during t2. The memory effect was observed irrespective of the time period of t2. The positive temperature perturbation (T1

  20. Time for the 70°C water precautionary option in the home dilution of powdered infant formula.

    PubMed

    Silano, Marco; Paganin, Paola; Davanzo, Riccardo

    2016-02-19

    Powdered infant formulas (PIF) are usually not sterile and may frequently be contaminated by several bacteria strains. Among them, Cronobacter species, previously known as Enterobacter sakazakii, is one of the most harmful, since it might be the causative agent of sepsis and meningitis in newborns and preterm infants during the first weeks of life. The mortality rate of these infections is up to 80 %. Therefore, some precautions are required in the home handling and dilution of PIF. Whereas there is wide consensus about the need that a PIF should be used immediately after being diluted or, if not, stored at < "5 °C", still recently the optimal temperature of the water used to dilute PIF is controversial among scientific societies and health agencies. The current knowledge is reviewed in this paper and provides sufficient evidence to cautiously advise the use of hot water at a temperature of "70 °C" in the dilution of PIF in order to prevent the Cronobacter sp. contamination and growth.

  1. Numerical simulation and dynamical analysis for low salinity water lens in the expansion area of the Changjiang diluted water

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-jing; Zhu, Shou-xian; Li, Xun-qiang; Ruan, Kun; Guan, Wei-bing; Peng, Jian

    2014-12-01

    The low salinity water lenses (LSWLes) in the expansion area of the Changjiang diluted water (CDW) exist in a certain period of time in some years. The impact of realistic river runoff, ocean currents and weather conditions need to be taken into account in the dynamical analysis of LSWL, which is in need of research. In this paper, the POM- σ- z model is used to set up the numerical model for the expansion of the CDW. Then LSWL in summer 1977 is simulated, and its dynamic mechanism driven by wind, tide, river runoff and the Taiwan Warm Current is also analyzed. The simulated results indicate that the isolated LSWL detaches itself from the CDW near the river mouth, and then moves towards the northeast region outside the Changjiang Estuary. Its maintaining period is from July 26 to August 11. Its formation and development is mainly driven by two factors. One is the strong southeasterly wind lasting for ten days. The other is the vertical tidal mixing during the transition from neap tide to spring tide.

  2. 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.

  3. 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’.

  4. β-1,3-D-glucan schizophyllan/poly(dA) triple-helical complex in dilute solution.

    PubMed

    Sanada, Yusuke; Matsuzaki, Tsubasa; Mochizuki, Shinichi; Okobira, Tadashi; Uezu, Kazuya; Sakurai, Kazuo

    2012-01-12

    A certain length of poly(deoxyadenylic acid) (dA(X)) can form a novel complex with β-1,3-D-glucan schizophyllan (SPG) with a stoichiometric composition of one dA binding two main chain glucoses. We measured dilute solution properties for the complex with light and small-angle X-ray scattering as well as intrinsic viscosity and found that the complex behaves as a semiflexible rod without branching or cross-linking. We analyzed the data with the wormlike cylinder model, and the chain dimensions and the persistence length for the complexes were consistently determined. The chain flexibility was reduced to almost 25% upon complexation for dA/SPG and to 15% for S-dA/SPG, where S-dA denotes the phosphorothioated DNA analogue. The changes in the molar mass per unit length and the diameter indicated that the helix was elongated or stretched along the axis direction upon the complexation.

  5. 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)

  6. Potential impact of a 500-mL water bolus and body mass on plasma osmolality dilution.

    PubMed

    Sollanek, Kurt J; Kenefick, Robert W; Cheuvront, Samuel N; Axtell, Robert S

    2011-09-01

    A methodological discrepancy exists in the hydration assessment literature regarding the establishment of euhydration, as some investigations utilize a pre-hydration technique, while others do not (overnight fluid/food fast). However, the degree that plasma osmolality (P (osm)) dilutes when using the pre-hydration method and how body mass/composition might influence the results is not known. Thirty subjects (22 M, 8 F; 20 ± 2 years (mean ± SD); 1.8 ± 0.1 m; 75.8 ± 13.5 kg) had P (osm) measured after an 8-h food and fluid fast (overnight fast) and 90 min after a 500-mL (4-9 mL/kg) water bolus (pre-hydration). From pre- to post-bolus, participants' P (osm) declined from 297 ± 3.5 to 295 ± 3.8 mmol/kg (p < 0.05; ∆ -1.7 ± 3.5 mmol/kg). One-third of the sample diluted to more than -3 mmol/kg. The effect of body mass on P (osm) dilution was investigated by comparing dilution in the ten lightest (62.8 ± 3.4 kg) and heaviest (92.0 ± 9.8 kg) participants; however, the change between the light (∆ -1.9 ± 3.8 mmol/kg) versus heavy groups (∆ -1.1 ± 3.0 mmol/kg) was not different (p > 0.05). The correlation between body mass or total body water and change in P (osm) was weak (p > 0.05), as was the correlation between relative fluid intake based on mass and change in P (osm) (p > 0.05). The two methodologies appear to produce similar P (osm) values when measured in most individuals. However, the potential for significant dilution (>3 mmol/kg) should be considered when choosing the pre-hydration methodology.

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

    DOE PAGES

    Zhang, Libing; Yan, Lishi; Wang, Zheming; ...

    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

  8. 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.

  9. 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.

  10. 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

  11. Recovery of propylene glycol from dilute aqueous solutions by complexation with organoboronates in ion-pair extractants

    SciTech Connect

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

    1996-04-01

    Recovery of propylene glycol (1,2-PD) from aqueous solution was studied in batch experiments using extractants consisting of ion pairs of Aliquat 336 and phenylboronate in 2-ethylhexanol, toluene, o-xylene, or diisobutyl ketone. The heterogeneous complexation constant {beta}{sub 11} calculated from the results of 25 C was highest in 2-ethylhexanol (49--100 (mol/L){sup {minus}1}). The equilibrium water concentration in the extractants was 8--12 wt% and decreased with increasing uptake of 1,2-PD. Nearly all extractant/diluent systems exhibited stoichiometric overloading. Evidence for aggregation of the ion-pair extractant in the organic phase was found from water solubilization studies and {sup 1}H NMR spectroscopy studies. The complexation constant decreased with increasing temperature. Up to 80% of the extracted 1,2-PD was back extracted into water after acidification with CO{sub 2}. The extractant could then be regenerated by stripping CO{sub 2} from solution at temperatures exceeding 110 C. However, at these temperatures the color of the extractant changes, and the extraction capacity is reduced to about 60% of its original value. Regeneration by contacting with aqueous solutions of Na{sub 2}CO{sub 3} did not cause extractant degradation; regeneration effectiveness increased with increasing pH.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Ion association of dilute aqueous potassium chloride and potassium hydroxide solutions to 600°C and 300 MPa determined by electrical conductance measurements

    NASA Astrophysics Data System (ADS)

    Ho, Patience C.; Palmer, Donald A.

    1997-08-01

    The limiting molar conductances ( Λ0) and ion association constants of dilute (<0.01 mol · kg -1) aqueous potassium chloride and hydroxide solutions were determined by electrical conductance measurements from 200 to 600°C and from 100 to 600°C, respectively, and pressures up to 300 MPa. The limiting molar conductances of KOH (aq) increase with increasing temperature up to 300°C and decreasing density. Above 400°C and densities between 0.8 and 0.4 g · cm -3 for KCl (aq) and between 0.8 and 0.6 g· cm -3 for KOH (aq), Λ0 is nearly temperature-independent but increases linearly with decreasing density. The molal ion association constants ( KA(m)) for both KCl (aq) and KOH (aq) increase with increasing temperature and decreasing solution density. At corresponding temperatures and densities, ion association of KCl (aq) is similar in extent to NaCl (aq), whereas for KOH (aq) the values are slightly lower than for NaOH (aq). The log KA(m) values for KCl (aq) and KOH( aq) were calculated using the Shedlovsky equation exclusively from data obtained at temperatures ≥400°C and can be represented as functions of temperature ( T, Kelvin) and the logarithm of water density ( ϱw, g · cm -3) as follows: log K A(m)(KCI) = 0.753 100.21/T - (10.316 - 3598.9/T) log φ w and log K A(m)(KOH) = 10183 - 132.61/T - (13.002 - 621.8/T) logφ w These expressions apply strictly at ϱw ≥ 0.4 g · cm -3 where the measurements are most precise.

  17. Analysis of acrylamide in water using a coevaporation preparative step and isotope dilution liquid chromatography tandem mass spectrometry.

    PubMed

    Chu, Shaogang; Metcalfe, Chris D

    2007-07-01

    Acrylamide is a probable human carcinogen, and the drinking water quality guideline for this compound is 0.5 mg/L. However, analysis of this compound in water is difficult because of its very high water solubility, which limits the efficiency of sample preconcentration prior to analysis. We developed a robust and sensitive analytical method for the determination of trace quantities of acrylamide in samples of water using a novel preparative technique and isotope dilution liquid chromatography tandem mass spectrometry with atmospheric pressure chemical ionization as the ion source (LC-APCI-MS/MS). The preparative method involves coevaporation of acrylamide with water at pH 10 using a rotary evaporator, followed by acidification to pH 3.0 and concentration of the sample prior to analysis by LC-APCI-MS/MS. To compensate for the loss of the analyte during sample preparation and signal suppression due to interference from the sample matrix, isotope dilution with acrylamide-d3 was used for quantitation. Using this method, analyte recoveries ranged from 74 to 103% for acrylamide spiked into water at a concentration of 0.4 ng/mL. The limit of detection and limit of quantification (LOQ) for acrylamide in water were 0.02 and 0.06 ng/mL, respectively. This method was successfully applied to determine trace levels of acrylamide in samples of river water and in runoff from an agricultural field to which municipal biosolids (i.e., sludge) had been applied. Concentrations of acrylamide in these samples ranged from

  18. Thermodynamics of Water and Aqueous Solutions under Mantle Conditions

    NASA Astrophysics Data System (ADS)

    Brown, J. M.; Vance, S.; Bollengier, O.; Shaw, G. H.; Abramson, E.

    2014-12-01

    Interactions between aqueous solutions and rocks extending from the surface and through the deep mantle control the state and evolution of Earth. The accurate representation of the fluid chemical energy as a function of pressure, temperature and composition over a wide range of conditions is prerequisite in understanding phase equilibria and solubilities in multicomponent systems. End-member thermodynamic properties of water (densities, specific heats, sound speeds, and more) have been extensively explored in a regime below about 100 MPa and an available complex formulation for the Helmholtz free energy (IAPWS-95) accurately represents these data and a smaller number of measurements extending to 1 GPa. However, this parameterization systematically misfits higher pressure data and is not easily adjusted to provide a better description. To address these points, we developed a flexible framework for the acquisition and description of Gibbs' free energy of water and aqueous solutions. Through use of local basis functions, the thermodynamic state surface can be adjusted to account for improved experimental constraints or for results in new regimes of pressure and temperature. Based on our experimental work on pure water, MgSO4(aq), Na2SO4(aq), and ammonia-water mixtures, new insights are provided on the volumetric behavior of fluids at high pressure. For the ionic solutions, where the partial molar volume at infinite dilution, Vo, is dominated by electrostriction at low pressure, the initial pressure derivative of Vo is large. At high pressure, where Vo is more related to the "size" of the ions, it is only weakly pressure dependent. The non-ideal behavior of these ionic solutions over an extended range of pressures and temperatures is successfully described using a standard three-term parameterization representing solvent (Debye-Hückel), solvent-ion, and ion-ion interactions. The solvent-ion and ion-ion interaction parameters show less dependence on pressure and

  19. Calculation of pH and mineral equilibria in hydrothermal waters with application to geothermometry and studies of boiling and dilution

    NASA Astrophysics Data System (ADS)

    Reed, Mark; Spycher, Nicolas

    1984-07-01

    Using chemical analyses and 25° pH measurements of quenched high-temperature waters, we calculate in situ pH and distribution of aqueous species at high temperature. This is accomplished by solving simultaneous mass action equations for complexes and redox equilibria and mass balance equations, on all components, including a H + equation with as many as 60 terms (depending on water composition). This calculation provides accurate values for the activities of aqueous ions in a given water at high temperature, which are used to calculate an ion activity product ( Q) for each of more than 100 minerals. The value of log( Q/ K) for each mineral, where K is the equilibrium constant, provides a measure of proximity of the aqueous solution to equilibrium with the mineral. By plotting log Q/ Kvs. T for natural waters, it is possible to determine: a) whether the water was in equilibrium with a host rock mineral assemblage, b) probable minerals in the equilibrium assemblage and c) the temperature of equilibrium. In cases where the fluid departs from equilibrium with a host rock assemblage, it is possible to determine whether this may result from boiling or dilution, and an estimate of amount of lost gas or diluting water can be determined. The calculation is illustrated by application to geothermal waters from Iceland, Broadlands, and Sulphur Bank, hot spring waters from Jemez, Yellowstone and Blackfoot Reservoir (Idaho) and fluid inclusions from the Sunnyside Mine, Colorado. It is shown that most geothermal waters approach equilibrium with a subsurface mineral assemblage at a temperature close to measured temperatures and that some hot springs also approach equilibrium with the host rock at temperatures above outlet temperatures but commonly below the Na-K-Ca temperatures. The log Q/ K plots show that some discrepancies between Na-K-Ca temperatures on spring waters and actual temperatures result from a failure of alkali feldspars to equilibrate with the fluid and with each

  20. Determination of infinite dilution activity coefficients and 1-octanol/water partition coefficients of volatile organic pollutants

    SciTech Connect

    Tse, G.; Sandler, S.I. . Dept. of Chemical Engineering)

    1994-04-01

    The characterization of pollutants is of growing interest as concerns about the environment increase. One parameter useful in predicting the fate of a chemical in the environment, the infinite dilution activity coefficient, has been determined here for several EPA priority pollutants in 1-octanol at 25 C using a relative gas-liquid chromatographic measurement technique. A simple correlation has been developed relating the limiting activity coefficients of a species in pure water and in pure 1-octanol to its octanol/water partition coefficient. Agreement between the experimental results and published values is very good. The method developed here of computing the octanol/water partition coefficient from gas chromatographic measurements of its infinite dilution activity coefficients is an improvement over traditional partition coefficient determination methods in that it is easier and quicker, without a loss of accuracy. Furthermore, the authors show that this method is applicable to chemicals covering a large range of hydrophobicities (1.0 < log K[sub OW] < 5.0).

  1. 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.

  2. 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.

  3. WaterNet:The NASA Water Cycle Solutions Network

    NASA Astrophysics Data System (ADS)

    Belvedere, D. R.; Houser, P. R.; Pozzi, W.; Imam, B.; Schiffer, R.; Schlosser, C. A.; Gupta, H.; Martinez, G.; Lopez, V.; Vorosmarty, C.; Fekete, B.; Matthews, D.; Lawford, R.; Welty, C.; Seck, A.

    2008-12-01

    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. Projections of the effects of such factors will remain speculative until more effective global prediction systems and applications are implemented. NASA's unique role is to use its view from space to improve water and energy cycle monitoring and prediction, and has taken steps to collaborate and improve interoperability with existing networks and nodes of research organizations, operational agencies, science communities, and private industry. WaterNet is a Solutions Network, devoted to the identification and recommendation of candidate solutions that propose ways in which water-cycle related NASA research results can be skillfully applied by partner agencies, international organizations, state, and local governments. It is designed 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 that address national needs.

  4. 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

  5. Dynamical properties of water-methanol solutions

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    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.

  6. The transition from dilute electrolyte aqueous solution to molten salt in geologic fluids: evidence from calcite solubility measurement in Na-halide solutions at 8 kbar and 700 °C

    NASA Astrophysics Data System (ADS)

    Galvez, M.; Manning, C. E.

    2014-12-01

    Fluids are major agents of mass and heat transport in the Earth crust and in subduction zones. Fluid inclusions, metasomatic field relations and experimental evidence suggest that these fluids can contain important ligands, including halogens, sulfates, sulfides, etc. The ligands participate in the complexation of rock-forming elements during mineral dissolution to high-T and P. Although models of high- element metasomatism typically assume that H2O dominates the fluid's solvent properties, however, H2O may be a relatively minor component in the high-PT brines that are increasingly recognized in the lower crust and mantle. Understanding the evolution of solubility mechanisms as fluids change from dilute aqueous solutions to salt-rich brines is hindered by the absence of experimental investigation of this transition. To address this problem, we conducted experiments on the solubility of calcite in sodium-halide solutions at 8 kbar and 700 °C using hydrothermal piston-cylinder weight-loss methods. Investigated salts were NaL , where L=F, Cl, Br, I, at concentrations ranging from 0.15 molal to 20 molal (XNaL ~ 0.3). At these conditions, the fluid is a single supercritical fluid phase . Run durations were 4 to 20 hours. Results demonstrate systematic trends with ligand ionic size, and locate a major mechanistic transition in the vicinity of XNaL~ 0.1 for all calcite-H2O-NaL systems. At lower than this critical composition (Xcrit), calcite solubility displays a pronounced concave shape indicating involvement of water during the dissolution process. At XNaL> Xcrit , the shape becomes convex with no apparent effect of decreased H2O activity in the fluid. The solubility patterns suggest that the solvent properties are dominated by those of H2O at XNaL< Xcrit, but at XNaL> Xcrit, H2O is a solute in a solution behaving as a molten salt. Geological evidence suggests that salt concentrations may reach values similar to or greater than Xcrit in a range of metamorphic and

  7. 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.

  8. 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.

  9. A conductance study of guanidinium chloride, thiocyanate, sulfate, and carbonate in dilute aqueous solutions: ion-association and carbonate hydrolysis effects.

    PubMed

    Hunger, Johannes; Neueder, Roland; Buchner, Richard; Apelblat, Alexander

    2013-01-17

    We study the conductance of dilute aqueous solutions for a series of guandinium salts at 298.15 K. The experimental molar conductivities were analyzed within the framework of the Quint-Viallard theory in combination with Debye-Hückel activity coefficients. From this analysis, we find no evidence for significant ion association in aqueous solutions of guanidinium chloride (GdmCl) and guanidinium thiocyanate (GdmSCN), and the molar conductivity of these electrolytes can be modeled assuming a complete dissociation. The limiting ionic conductivity of the guanidinium ion (Gdm(+)) is accurately determined to λ(Gdm(+)) = 51.45 ± 0.10 S cm(2) mol(-1). For the bivalent salts guanidinium sulfate (Gdm(2)SO(4)) and guanidinium carbonate (Gdm(2)CO(3)), the molar conductivities show small deviations from ideal (fully dissociated electrolyte) behavior, which are related to weak ion association in solution. Furthermore, for solutions of Gdm(2)CO(3), the hydrolysis of the carbonate anion leads to distinctively increased molar conductivities at high dilutions. The observed ion association is rather weak for all studied electrolytes and cannot explain the different protein denaturing activities of the studied guanidinium salts, as has been proposed previously.

  10. Solute Export Through Transpiration: A Possible Control of Soil Water Chemistry?

    NASA Astrophysics Data System (ADS)

    Alexander, S. C.; Boyle, D. B.; Alexander, E. C.

    2005-12-01

    Recent studies of soil and ground water interactions in western Minnesota have produced seemingly anomalous results. The soil waters beneath highly transpirative plants (Typha sp., Salix sp. and Populus sp.) in a ground water discharge area developed high calcium sulfate concentrations with only minor enrichment of sodium and chloride. It was expected that concentration of solutes by evapo-transpiration would enrich all ions in the originating ground water more equally. Transpired water is generally assumed to be essentially distilled water although there is little analytical data to support this hypothesis. Given the very high evapotranspiration rates of Western Minnesota, greater than 95% of total water movement, even relatively dilute ion concentrations in the transpired water may be significant in the total chemical budget. To investigate the chemistry of transpired water we adapted techniques that have been used to study total transpiration rates as well as isotopic composition of transpired waters. Our initial results from typha sp. have produced waters that while relatively dilute are distinctly not distilled water. Control samples using de-ionized water over dead vegetation produced minor ion enrichment. All results are in ppm. Ion - Ca, Mg, Na, K, P, Mn, Cl , SO4, NO3-N soil water - 18.5, 2.9, 4.8, 3.8, 0.2, 0.2, 5.6, 2.4, 0.5 transpiration - 1.9, 0.6, 1.5, 8.5, 0.3, 0.4, 9.0, 1.6, <0.1 DI control - 0.1, <0.1, 0.1, <0.1, <0.1, <0.1, <0.1, 1.6, <0.1 The observed transpiration chemistries are in rough agreement with reported literature values for plant stem water. While many plants are known to excrete large molecules the expulsion of ions in transpired water would represent a novel chemical plant pathway.

  11. Electron spin resonance of diluted solid solutions of Gd{sub 2}O{sub 3} in CeO{sub 2}

    SciTech Connect

    Biasi, R.S. de . E-mail: rsbiasi@ime.eb.br; Grillo, M.L.N. . E-mail: mluciag@uerj.br

    2005-06-15

    Electron spin resonance spectra of Gd{sup 3+} in diluted solid solutions of Gd{sub 2}O{sub 3} in CeO{sub 2} have been studied at room temperature for Gd concentrations between 0.01 and 1.00mol%. While in the case of Mn{sup 2+}:CeO{sub 2} samples, both the linewidth and the line intensity go through a maximum between 0.2 and 0.4% Mn and then start to decrease, in the case of Gd{sup 3+}:CeO{sub 2} samples the linewidth and the line intensity increase monotonically with the dopant concentration. This as taken as evidence that in Gd{sub 2}O{sub 3}-CeO{sub 2} diluted solid solutions there are no clustering effects similar to the ones observed in Mn:CeO{sub 2} solid solutions. It is not clear why clustering effects are present in Mn:CeO{sub 2} solid solutions and not in Gd:CeO{sub 2} solid solutions; however, it seems reasonable to assume that this is due to the fact that the ionic radius of Mn{sup 2+} (81 pm) is about 25% smaller that that of Gd{sup 3+} (107.8pm). In any case, the fact that Gd:CeO{sub 2} solid solutions do not exhibit clustering effects means that ESR linewidth data can be used to estimate the concentration of Gd in CeO{sub 2} samples, as it is possible to do in several solid solutions of paramagnetic ions in ceramic materials. The results also suggest that the range of the exchange interaction between Gd{sup 3+} ions in CeO{sub 2} is about 0.89nm.

  12. Water proton relaxation in dilute and unsaturated suspensions of non-porous particles.

    PubMed

    Hills, B P

    1994-01-01

    NMR water proton relaxation times are reported for suspensions of silica powder of varying silica/water ratios. Pore size distributions and pore connectivities are derived from the relaxation time distributions for the water-saturated suspension. Capillary theory appears to explain the relaxation behaviour of the unsaturated, packed suspensions. The relaxation data in suspensions that have lower solid/liquid ratios than the saturated, packed suspension are sensitive to the particular radial distribution function. This is analysed with a simple cluster model.

  13. 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.

  14. Effect of ice growth rate on the measured Workman-Reynolds freezing potential between ice and dilute NaCl solutions.

    PubMed

    Wilson, P W; Haymet, A D J

    2010-10-07

    Workman-Reynolds freezing potentials have been measured across the interface between ice and dilute NaCl solutions as a function of ice growth rate for three salt concentrations. Growth rates of up to 40 μm·s(-1) are used, and it is found that the measured voltage peaks at rates of ∼25 μm·s(-1). Our initial results indicate that the freezing potential can be used as a probe into various aspects of the DC electrical resistance of ice as a function of variables such as salt concentration.

  15. Experimental assessment of on-chip liquid cooling through microchannels with de-ionized water and diluted ethylene glycol

    NASA Astrophysics Data System (ADS)

    Won, Yonghyun; Kim, Sungdong; Eunkyung Kim, Sarah

    2016-06-01

    Recent progress in Si IC devices, which results in an increase in power density and decrease in device size, poses various thermal challenges owing to high heat dissipation. Therefore, conventional cooling techniques become ineffective and produce a thermal bottleneck. In this study, an on-chip liquid cooling module with microchannels and through Si via (TSV) was fabricated, and cooling characteristics were evaluated by IR measurements. Both the microchannels and TSVs were fabricated in a Si wafer by deep reactive ion etching (DRIE) and the wafer was bonded with a glass wafer by a anodic bonding. The fabricated liquid cooling sample was evaluated using two different coolants (de-ionized water and 70 wt % diluted ethylene glycol), and the effect of coolants on cooling characteristics was investigated.

  16. 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

  17. Short communication: milk output in llamas (Lama glama) in relation to energy intake and water turnover measured by an isotope dilution technique.

    PubMed

    Riek, A; Klinkert, A; Gerken, M; Hummel, J; Moors, E; Südekum, K-H

    2013-03-01

    Despite the fact that llamas have become increasingly popular as companion and farm animals in both Europe and North America, scientific knowledge on their nutrient requirements is scarce. Compared with other livestock species, relatively little is known especially about the nutrient and energy requirements for lactating llamas. Therefore, we aimed to measure milk output in llama dams using an isotope dilution technique and relate it to energy intakes at different stages of lactation. We also validated the dilution technique by measuring total water turnover (TWT) directly and comparing it with values estimated by the isotope dilution technique. Our study involved 5 lactating llama dams and their suckling young. Milk output and TWT were measured at 4 stages of lactation (wk 3, 10, 18, and 26 postpartum). The method involved the application of the stable hydrogen isotope deuterium ((2)H) to the lactating dam. Drinking water intake and TWT decreased significantly with lactation stage, whether estimated by the isotope dilution technique or calculated from drinking water and water ingested from feeds. In contrast, lactation stage had no effect on dry matter intake, metabolizable energy (ME) intake, or the milk water fraction (i.e., the ratio between milk water excreted and TWT). The ratios between TWT measured and TWT estimated (by isotope dilution) did not differ with lactation stage and were close to 100% in all measurement weeks, indicating that the D(2)O dilution technique estimated TWT with high accuracy and only small variations. Calculating the required ME intakes for lactation from milk output data and gross energy content of milk revealed that, with increasing lactation stage, ME requirements per day for lactation decreased but remained constant per kilogram of milk output. Total measured ME intakes at different stages of lactation were similar to calculated ME intakes from published recommendation models for llamas.

  18. Investigation of cascade-induced re-solution from nanometer sized coherent precipitates in dilute Fe-Cu alloys

    NASA Astrophysics Data System (ADS)

    Certain, A.; Lee Voigt, H.-J.; Allen, T. R.; Wirth, B. D.

    2013-01-01

    Molecular dynamics (MD) simulations have been used to investigate the re-solution of copper atoms from coherent, nanometer-sized copper precipitates in a body-centered cubic iron matrix. The molecular dynamics simulations used Finnis-Sinclair type interatomic potentials to describe the Fe-Cu system. Precipitate diameters of 1, 3 and 5 nm were studied, with primary knock-on atom (PKA) from 1 to 100 keV, although the majority of the cascade simulations and analysis of solute re-solution were performed for cascades of 10 or 20 keV. The simulation results provide an assessment of the re-solution on a per-atom basis as a function of precipitate size, cascade location and energy. Smaller sized precipitates, with a larger surface to volume ratio, experienced larger re-solution on a per-atom basis than larger precipitates. Re-solution was observed to occur predominantly in the initial ballistic stages of the cascades when atomic collisions occur at high kinetic energy. A minimum PKA energy of around 1 keV was required to produce re-solution, and the amount of re-solution appears to saturate for PKA energies above approximately 10 keV, indicating that the MD results are representative of the energy range of interest. A model for prompt, cascade induced solute atom re-solution has been derived, following the approach used to describe fission gas bubble re-solution, and the parameters for describing copper atom re-solution are provided.

  19. 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.

  20. Role of naphthenic acids in stabilizing water-in-diluted model oil emulsions.

    PubMed

    Gao, Song; Moran, Kevin; Xu, Zhenghe; Masliyah, Jacob

    2010-06-17

    The need for alkaline conditions in oil sands processing is, in part, to produce natural surfactants from bitumen. Previous studies have shown that the produced surfactants are primarily carboxylic salts of naphthenic acids with the possibility of sulfonic salts as well. The role of these natural surfactants, particularly those in the naphthenate class, is to provide a physicochemical basis for several subprocesses in bitumen extraction. In this study, it was found that the content of indigenous naphthenic acids in bitumen can destabilize, to some extent, the water-in-oil emulsion by lowering the interfacial tension, reducing the rigidity and promoting the coalescence of water droplets.

  1. Determination of ultratrace levels of tributyltin in waters by isotope dilution and gas chromatography coupled to tandem mass spectrometry.

    PubMed

    Rodríguez-Cea, Andrés; Rodríguez-González, Pablo; Font Cardona, Nuria; Aranda Mares, José Luís; Ballester Nebot, Salomé; García Alonso, J Ignacio

    2015-12-18

    The current EU legislation lays down the Environmental Quality Standards (EQS) of 45 priority substances in surface water bodies. In particular, the concentration of tributyltin (TBT) must not exceed 0.2ngL(-1) and analytical methodologies with a Limit of Quantification (LOQ) equal or below 0.06ngL(-1) are urged to be developed. This work presents a procedure for the determination of ultratrace levels of TBT in water samples by Isotope Dilution and GC-MS/MS operating in Selected Reaction Monitoring (SRM) mode which meets current EU requirements. The method requires the monitorization of five consecutive transitions (287>175 to 291>179) for the sensitive and selective detection of TBT. The measured isotopic distribution of TBT fragment ions was in agreement with the theoretical values computed by a polynomial expansion algorithm. The combined use of Tandem Mass Spectrometry, a sample volume of 250mL, the preconcentration of 1mL of organic phase to 30μL and an injection volume of 25μL by Programmed Temperature Vaporization provided a LOQ of 0.0426ngL(-1) for TBT (calculated as ten times the standard deviation of nine independent blanks). The recovery for TBT calculated in Milli-Q water at the EQS level was 106.3±4%. A similar procedure was also developed for the quantification of dibutyltin (DBT) and monobutyltin (MBT) in water samples showing satisfactory results. The method was finally implemented in a routine testing laboratory to demonstrate its applicability to real samples obtaining quantitative recoveries for TBT at the EQS level in mineral water, river water and seawater.

  2. 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…

  3. 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.

  4. 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).

  5. 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.

  6. 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

  7. 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.

  8. The Effects of Aging on the Luminescence of PEG-Coated Water-Soluble ZnO Nanoparticles Solutions

    SciTech Connect

    Woo, Boon K.; Chen, Wei; Joly, Alan G.; Sammynaiken, Ramaswami

    2008-09-18

    Water-soluble ZnOnanoparticles coated with polyethylene glycol biscarboxymethyl (PEG(COOH)2)were prepared in ethanol/water solutions. The ZnOnanoparticles have a hexagonal structure with an average size of 10 nm. Three different luminescence bands are observed from the nanoparticle solutions: green emission at 530 nm from surface states or defects, UV emission at 380 nm from the ZnOexcitons, and an emission band at around 338 nm from the PEG(COOH)2. The fresh as-prepared samples have very strong green emission at 530 nm from surface states or defects but very weak excitonic emission at 380 nm. After dilution with ethanol, the green emission decreases in intensity and the excitonic emission increases. In the diluted samples, the excitonic luminescence intensity increases with storage time. This intensity increase is attributed to surface passivation by CH3COO-ligands resulting from precursor reactions in the ethanol solvent.

  9. 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.

  10. Equilibrium adsorption studies of some aromatic pollutants from dilute aqueous solutions on activated carbon at different temperatures

    SciTech Connect

    Khan, A.R.; Ataullah, R.; Al-Haddad, A.

    1997-10-01

    Aqueous solutions of phenol, p-chlorophenol, and p-nitrophenol have been used to determine the adsorption isotherm for single solute systems on activated carbon at different temperatures. The experimental program has been conducted to investigate the influence of concentration and temperature. All the reported equilibrium isotherm equations have been tried on present and published experimental data. A generalized isotherm equation which was proposed by Khan et al. and tested for bi-solute adsorption data has been modified for single-solute system. The temperature dependency has also been incorporated into a generalized equation. It has been noticed that the Radke and Prausnitz and generalized isotherm equations could represent the entire data with a minimum average percentage error. The influence of different adsorbents, sorbate concentrations, and pH of aqueous solutions has also been discussed in detail. The temperature dependency has been investigated using both the Dubinin-Astakov and the modified generalized equation. The generalized equation describes the experimental and published data adequately and provides a single value of differential molar heat of adsorption, {Delta}H{sub ads}, for a single solute adsorption system. The Dubinin-Astakov isotherm equation has shown an increasing trend of {Delta}H{sub ads} as the loading of adsorbent has increased.

  11. Microwave superheated water and dilute alkali extraction of brewers' spent grain arabinoxylans and arabinoxylo-oligosaccharides.

    PubMed

    Coelho, Elisabete; Rocha, M Angélica M; Saraiva, Jorge A; Coimbra, Manuel A

    2014-01-01

    Microwave superheated water extractions (MWE) were performed to evaluate the feasibility of this technology for quantitative recovery of the arabinoxylans (AX) or arabinoxylo-oligosaccharides (AXOS) from brewers' spent grain (BSG). The AX+AXOS yield increased with the increase of the temperature in the range from 140 to 210 °C during 2 min. The higher temperatures promoted depolymerisation, debranching, and deesterification of the polysaccharides, with formation of brown products. The conditions that promote a compromise between the yield and the structure obtained, minimizing the thermal degradation of the fractions extracted by MWE are the following: (1) 140 °C, to remove the residual starch mixed with β-glucans; (2) Suspension of the residue left in water and treated at 180 °C; (3) suspension of the residue in 0.1 M KOH and treated at 180 °C. Using this sequential procedure, it was possible to extract 62% of BSG AX+AXOS, presenting degrees of polymerization ranging between 7 and 24 xylose residues, and a degree of phenolic acids esterification between 5 and 21%. The structural variability obtained by MWE allows defining specific types of compounds for different applications and uses depending on the extraction conditions used.

  12. The influence of gravity on the precise measurement of solute diffusion coefficients in dilute liquid metals and metalloids.

    PubMed

    Smith, Reginald W; Zhu, Xiaohe; Tunnicliffe, Mark C; Smith, Timothy J N; Misener, Lowell; Adamson, Josee

    2002-10-01

    It is now well known that the diffusion coefficient (D) measured in a laboratory in low earth orbit (LEO) is less than the corresponding value measured in a terrestrial laboratory. However, all LEO laboratories are subject to transient accelerations (g-jitter) superimposed on the steady reduced gravity environment of the space platform. In measurements of the diffusion coefficients for dilute binary alloys of Pb-(Ag, Au,Sb), Sb-(Ga,In), Bi-(Ag,Au,Sb), Sn-(Au,Sb), Al-(Fe, Ni,Si), and In-Sb in which g-jitter was suppressed, it was found that D proportional to T (temperature) if g-jitter was suppressed, rather than D proportional to T(2) as observed by earlier workers with g-jitter present. Furthermore, when a forced g-jitter was applied to a diffusion couple, the value measured for D increased. The significance of these results is reviewed in the light of recent work in which ab initio molecular dynamics simulations predicted a D proportional to T relationship.

  13. 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.…

  14. 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.

  15. 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…

  16. Molar mass, radius of gyration and second virial coefficient from new static light scattering equations for dilute solutions: application to 21 (macro)molecules.

    PubMed

    Illien, Bertrand; Ying, Ruifeng

    2009-05-11

    New static light scattering (SLS) equations for dilute binary solutions are derived. Contrarily to the usual SLS equations [Carr-Zimm (CZ)], the new equations have no need for the experimental absolute Rayleigh ratio of a reference liquid and solely rely on the ratio of scattered intensities of solutions and solvent. The new equations, which are based on polarizability equations, take into account the usual refractive index increment partial differential n/partial differential rho(2) complemented by the solvent specific polarizability and a term proportional to the slope of the solution density rho versus the solute mass concentration rho(2) (density increment). Then all the equations are applied to 21 (macro)molecules with a wide range of molar mass (0.2500 kg mol(-1)), for which the scattered intensity is no longer independent of the scattering angle, the new equations give the same value of the radius of gyration as the CZ equation and consistent values of the second virial coefficient.

  17. 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.

  18. Aspartic acid interaction with cobalt(II) in dilute aqueous solution: A 57Co emission Mössbauer spectroscopic study

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Homonnay, Zoltan; Kuzmann, Erno; Vértes, Attila

    2012-03-01

    Emission (57Co) Mössbauer spectra of the aspartic acid—57CoCl2 system were measured at T = 80 K in frozen aqueous solution and in the form of a dried residue of this solution. The Mössbauer spectra, besides a weak contribution from after-effects, showed two Fe2 + /Co2 + components which were ascribed to octahedrally and tetrahedrally coordinated 57CoII microenvironments in the Asp-cobalt(II) complex. This dual coordination mode may be due to the involvement of the second terminal carboxylic group of aspartic acid in the coordination sphere of Co.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. Synthesis and Application of Organic Phosphonate Salts as Draw Solutes in Forward Osmosis for Oil-Water Separation.

    PubMed

    Long, Qingwu; Shen, Liang; Chen, Rongbiao; Huang, Jiaqi; Xiong, Shu; Wang, Yan

    2016-11-01

    The development of suitable draw solution in forward osmosis (FO) process has attracted the growing attention for water treatment purpose. In this study, a series of organic phosphonate salts (OPSs) are synthesized by one-step Mannich-like reaction, confirmed by FTIR and NMR characterizations, and applied as novel draw solutes in FO applications. Their solution properties including osmotic pressures and viscosities, as well as their FO performance as a function of the solution concentration are investigated systematically. In FO process, a higher water flux of 47-54 LMH and a negligible reverse solute flux can be achieved in the PRO (AL-DS) mode (active layer faces the draw solution) using a homemade thin-film composite membrane (PSF-TFC) and deionized water as the feed solution. Among all OPS draw solutes, the tetraethylenepentamine heptakis(methylphosphonic) sodium salt (TPHMP-Na) exhibits the best FO flux at 0.5 mol/kg concentration, which is further applied for the separation of emulsified oil-water mixture. The recovery of diluted OPS solutions is carried out via a nanofiltration (NF) system with a rejection above 92%. The aforementioned features show the great potential of OPS compounds as a novel class of draw solutes for FO applications.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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)

  12. 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.

  13. Accurate integral equation theory for the central force model of liquid water and ionic solutions

    NASA Astrophysics Data System (ADS)

    Ichiye, Toshiko; Haymet, A. D. J.

    1988-10-01

    The atom-atom pair correlation functions and thermodynamics of the central force model of water, introduced by Lemberg, Stillinger, and Rahman, have been calculated accurately by an integral equation method which incorporates two new developments. First, a rapid new scheme has been used to solve the Ornstein-Zernike equation. This scheme combines the renormalization methods of Allnatt, and Rossky and Friedman with an extension of the trigonometric basis-set solution of Labik and co-workers. Second, by adding approximate ``bridge'' functions to the hypernetted-chain (HNC) integral equation, we have obtained predictions for liquid water in which the hydrogen bond length and number are in good agreement with ``exact'' computer simulations of the same model force laws. In addition, for dilute ionic solutions, the ion-oxygen and ion-hydrogen coordination numbers display both the physically correct stoichiometry and good agreement with earlier simulations. These results represent a measurable improvement over both a previous HNC solution of the central force model and the ex-RISM integral equation solutions for the TIPS and other rigid molecule models of water.

  14. 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.

  15. 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.

  16. Experimental design for TBT quantification by isotope dilution SPE-GC-ICP-MS under the European water framework directive.

    PubMed

    Alasonati, Enrica; Fabbri, Barbara; Fettig, Ina; Yardin, Catherine; Del Castillo Busto, Maria Estela; Richter, Janine; Philipp, Rosemarie; Fisicaro, Paola

    2015-03-01

    In Europe the maximum allowable concentration for tributyltin (TBT) compounds in surface water has been regulated by the water framework directive (WFD) and daughter directive that impose a limit of 0.2 ng L(-1) in whole water (as tributyltin cation). Despite the large number of different methodologies for the quantification of organotin species developed in the last two decades, standardised analytical methods at required concentration level do not exist. TBT quantification at picogram level requires efficient and accurate sample preparation and preconcentration, and maximum care to avoid blank contamination. To meet the WFD requirement, a method for the quantification of TBT in mineral water at environmental quality standard (EQS) level, based on solid phase extraction (SPE), was developed and optimised. The quantification was done using species-specific isotope dilution (SSID) followed by gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The analytical process was optimised using a design of experiment (DOE) based on a factorial fractionary plan. The DOE allowed to evaluate 3 qualitative factors (type of stationary phase and eluent, phase mass and eluent volume, pH and analyte ethylation procedure) for a total of 13 levels studied, and a sample volume in the range of 250-1000 mL. Four different models fitting the results were defined and evaluated with statistic tools: one of them was selected and optimised to find the best procedural conditions. C18 phase was found to be the best stationary phase for SPE experiments. The 4 solvents tested with C18, the pH and ethylation conditions, the mass of the phases, the volume of the eluents and the sample volume can all be optimal, but depending on their respective combination. For that reason, the equation of the model conceived in this work is a useful decisional tool for the planning of experiments, because it can be applied to predict the TBT mass fraction recovery when the

  17. 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...

  18. Effects of Water Solutions on Extracting Green Tea Leaves

    PubMed Central

    Huang, Wen-Ying; Lin, Yu-Ru; Ho, Ruei-Fen; Liu, Ho-Yen

    2013-01-01

    This study investigates the effects of water solutions on the antioxidant content of green tea leaf extracts. Green teas prepared with tap water and distilled water were compared with respect to four antioxidant assays: total phenol content, reducing power, DMPD assay, and trolox equivalent antioxidant capacity assay. The results indicate that green tea prepared with distilled water exhibits higher antioxidant activity than that made with tap water. The high performance liquid chromatography showed that major constituents of green tea were found in higher concentrations in tea made with distilled water than in that made with tap water. This could be due to less calcium fixation in leaves and small water clusters. Water solutions composed of less mineralisation are more effective in promoting the quality of green tea leaf extracts. PMID:23997676

  19. Water structure around peptide fragments in aqueous solutions

    SciTech Connect

    McLain, Sylvia E; Soper, Alan K; Watts, Prof Anthony

    2008-01-01

    The bulk water structure around small peptide fragments - glycyl-L-alanine, glycyl-L-proline and L-alanyl-L-proline - has been determined by a combination of neutron diffraction with isotopic substitution and empirical potential structural refinement techniques. The addition of each of the dipeptides to water yields a decreased water-water coordination in the surrounding water solvent. Additionally both the Ow-Ow radial distribution functions and the water-water spatial density functions in all of the solutions indicate an electrostrictive effect in the second water coordination shell of the bulk water network. This effect is not observed in similar experiments on the amino acid L-proline alone in solution, which is one component of two of the peptides measured here.

  20. 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

  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.

  3. 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.

  4. Favoring the birth of female puppies after artificial insemination using chilled semen diluted with powdered coconut water (ACP-106c).

    PubMed

    Uchoa, Daniel Couto; da Silva, Ticiana Franco Pereira; Cardoso, Janaína de Fátima Saraiva; Mota Filho, Antônio Cavalcante; Jucá, Ricardo Parente; Silva, Alexandre Rodrigues; da Silva, Lúcia Daniel Machado

    2012-06-01

    The objective was to determine the effect of powdered coconut water extender (ACP-106c) on the proportion of female puppies born. Twenty French Bulldog bitches were subjected to natural mating (NM) and, during the subsequent two estrus periods, were bred by intravaginal artificial insemination (AI), using chilled semen (from the same males) diluted in Tris-egg yolk (AI-Tris) or ACP-106c (AI-ACP-106c). Fresh semen was cooled to 5 °C and maintained at that temperature for 6 h, rewarmed (37 °C for 30 s), and used for AI. Pregnancy and whelping rates following NM were both 100% and were both 90.0% following AI with either extender. Litter size (mean ± SD) was 5.4 ±1.1, 4.7 ± 2.0, and 5.1 ± 2.0 (P > 0.05) for NM, AI-Tris, and AI-ACP-106c, respectively. Furthermore, for these groups, the number of female vs. male puppies born were 2.6 ± 0.6 vs. 2.8 ± 1.0, 2.2 ± 1.0 vs. 2.5 ± 1.1, and 3.4 ± 1.6 vs. 1.8 ± 1.2 (P < 0.05 for AI-ACP-106c only). In conclusion, our hypothesis was supported; AI of semen in ACP-106c extender resulted in a significantly higher proportion of female puppies. Furthermore, this extender yielded acceptable litter size and rates of pregnancy and whelping.

  5. CO(v=1) population lifetimes of metal-carbonyl cluster compounds in dilute CHCl3 solution

    NASA Astrophysics Data System (ADS)

    Heilweil, E. J.; Cavanagh, R. R.; Stephenson, J. C.

    1988-07-01

    Tunable infrared picosecond pulses in the 5 μ region have been used for time-resolved pump-probe measurements of the population relaxation lifetime (T1) of CO(v=1) stretching vibrations in a series of metal-carbonyl cluster compounds in room temperature chloroform solution. T1 was the same for symmetric (ν=2084 cm-1, 90±10 ps) and antisymmetric (2014 cm-1, 87±10 ps) modes of the dicarbonyl Rh(CO)2(C5H7O2); T1 was the same for the B1 (2092 cm-1, 710±130 ps) and B2 (2036 cm-1, 750±90 ps) modes of Rh2(CO)4Cl2. Similarly long T1 times were found for Rh4(CO)12 (2075 cm-1, 610±65 ps) and Rh6(CO)16 (2077 cm-1, 700±100 ps). The molecule Co4(CO)12 has also been compared to the corresponding rhodium analog and it exhibits an initially fast relaxation of 47±5 ps followed by a slower 396±70 ps decay. The transient response of the more complex systems to the single frequency experiment is found to be sensitive to frequency and can exhibit bleaching, absorption, and a combination of these effects. Such behavior is attributed to overlap of the IR pulse with v=1 to v=2 and higher transitions in the M4(CO)12 (M=Rh or Co) and Rh6(CO)16 molecules. The long CO(v=1) T1 values for the metal cluster molecules suggest relaxation via multiquantum transfer of vibrational energy to adjacent M-C stretch and M-C-O bend vibrations; energy transfer to vibrational or electronic states of the central metal core seems unimportant in determining T1 for these systems.

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

    PubMed

    Chang, E-E; Wan, Jan-Chi; Kim, Hyunook; 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, K(ow). 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 K(ow) was replaced by the one with larger K(ow). 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.

  7. Heat and Mass Diffusions in the Absorption of Water Vapor by Aqueous Solution of Lithium Bromide

    NASA Astrophysics Data System (ADS)

    Kashiwagi, Takao; Kurosaki, Yasuo; Nikai, Isao

    The recent development of absorption-type heat pump is highly essential from the viewpoint of extracting the effective energy from waste heat or solar energy. To increase the efficiency of energy conversion, it is important to improve the performance of absorbers. The objective of this paper is to obtain an increased understanding of the fine mechanisms of vapor absorption. A system combining holographic interferometry wity thermometry is adopted to observe the progress of one-dimensional water vapor absorption by aqueous solution of lithium bromide (LiBr) and also to measure the unsteady temperature and concentration distributions in the absorption process. The experiments are carried out under the condition that the solution surface is exposed to the saturated water vapor at reduced pressure, and the effects of LiBr mass concentration on absorption mechanism are examined in the concentration range 20-60 mass%. The interference fringes are analyzed to distinguish between the layers of heat conduction and mass diffusion. The temperature and concentration distributions thus determined experimentally are compared with numerical solutions obtained by the equations for unsteady heat conduction and mass diffusion taking into consideration the effect of heat by dilution, to give reasonable values of mass diffusivity hitherto remaining unknown. Especially in the range of 40-60 mass%, the mass diffusivity decreases extremely with the increase of mass concentration of LiBr and it falls down to 0.7-0.8×10-9 m2/s in case of 60 mass% solution.

  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.

  9. 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.

  10. Design, synthesis and characterization of bio/electroactive hybrids: Confining chromophores in dilute solutions using a helical peptide template

    NASA Astrophysics Data System (ADS)

    Kas, Onur Y.

    are accessible via the use of this peptide template strategy. With only minor changes in the amino acid sequences the templates can arrange small methylstilbene molecules at 6 A spacing with a cofacial orientation where interactions are present, at 11 A on the same side, and at an offset orientation where interactions are absent. The extent and type of the interactions depend strongly on the subtle variations in side chain presentation on the template. Longer chromophores, OXA-PPV oligomers, were also confined on the same templates which highlighted the effects of conjugation length. It was found that 11 A spacing was not sufficient for avoiding intermolecular interactions of longer chromophores. Interpreting the photophysical data, it was speculated that minor changes in the spacing and orientation of the electroactive molecules with respect to each other might change the type of species that they form after initial photoexcitation namely excitons, excimers, or spatially indirect excitons. It was concluded that this peptide templated system, even though in solution, can be utilized to elucidate the not very well understood complex photophysical phenomena happening in relatively aggregated morphologies like in thin films used in actual devices. It was also suggested that after minimal changes in the amino acid sequence these templates can be used for studying intermolecular distance and orientation dependence of fluorescence resonance energy transfer (FRET) and exciton splitting in PV devices. The final chapter describes a completely different method for controlling intermolecular distance and orientation. Micron size polymer blend phase separation behavior was investigated in systems that also undergo photoisomerization reactions. Theories and previous experimental findings were substantiated by the experimental results obtained using polystyrenes decorated with trans-stilbene sidechains, synthesized via Heck reaction. Increase in the domain sizes upon UV irradiation

  11. 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.

  12. Hydrogen bonding between acetate-based ionic liquids and water: Three types of IR absorption peaks and NMR chemical shifts change upon dilution

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Cao, Yuanyuan; Zhang, Yuwei; Mu, Tiancheng

    2014-01-01

    The hydrogen-bonding interaction between acetate-based ionic liquids (AcIL) and water was investigated by attenuated total reflection infrared (ATR-IR) and 1H NMR. Interestingly, the relative change of chemical shift δ of 1H NMR upon dilution could be divided into three regions. All the H show an upfield shift in Regions 1 and 2 while a different tendency in Region 3 (upfield, no, and downfield shift classified as Types 1, 2, 3, respectively). For ATR-IR, the red, no, or blue shift of νOD (IR absorption peak of OD in D2O) and ν± (IR absorption peak of AcILs) also have three types, respectively. Two-Times Explosion Mechanism (TTEM) was proposed to interpret the dynamic processes of AcILs upon dilution macroscopically, meanwhile an Inferior Spring Model (ISM) was proposed to help to understand the TTEM microscopically, All those indicate that AcILs present the state of network, sub-network, cluster, sub-cluster, ion pairs and sub-ion pairs in sequence upon dilution by water and the elongation of hydrogen bonding between AcILs-water, between cation-anion of AcILs is plastic deformation rather than elastic deformation.

  13. 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.

  14. 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

  15. Explicit-water molecular dynamics study of a short-chain 3,3 ionene in solutions with sodium halides

    NASA Astrophysics Data System (ADS)

    Druchok, M.; Vlachy, V.; Dill, K. A.

    2009-04-01

    Ionenes are alkyl polymer chains in which hydrophobic groups are separated by ionic charges. They are useful for studying the properties of water as a solvent because they demonstrate a sufficiently complex combination of hydrophobicity, charge interactions, and specific-ion effects that some properties cannot be predicted by implicit-solvation theories. On the other hand, they are simple enough that their molecular structures can be varied and controlled in systematic experiments. In particular, implicit-solvent models predict that all such solutes will have negative enthalpies of dilution, whereas experiments show that enthalpies of dilution are positive for the chaotropic counterions. Here, we study ionenes that are short chains (six monomer units) in solutions of different counterions, with sodium as the coion by molecular dynamics simulations in explicit water. We explore the pair distributions of various atoms within the system at three different temperatures: T =278, 298, and 318 K. We find (i) that the molecular dynamics simulations are consistent with the experimental trends for the osmotic coefficients and enthalpies of dilution, (ii) that the fluorine-nitrogen and fluorine-carbon correlations decrease with decreasing temperature, (iii) while the opposite behavior is found for iodine ions, and (iv) that in the counterion-Na+ pair distributions, too, fluorine ions behave oppositely to iodine ions upon temperature increase.

  16. 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

  17. Device separates hydrogen from solution in water at ambient temperatures

    NASA Technical Reports Server (NTRS)

    Albright, C. F.

    1969-01-01

    Separator decreases the partial pressure of hydrogen gas dissolved in the water produced by fuel cells containing an alkaline electrolyte. The unit eliminates the hazards associated with the release of hydrogen from water solution when the hydrostatic pressure is rapidly decreased.

  18. Infinite dilution activity coefficients from ab initio solvation calculations

    SciTech Connect

    Lin, S.T.; Sandler, S.I.

    1999-12-01

    A Group Contribution Solvation (GCS) model was developed to calculate infinite dilution activity coefficients ({gamma}{sup {chi}}) based on modern computational chemistry. The GCS model results in an average error of 7% in {gamma}{sup {chi}} for the limited number of data points among water, n-hexane, acetonitrile and n-octanol, whereas the errors are 47% and 52% with the UNIFAC model and the modified UNIFAC model, respectively. GCS was also used to calculate infinite dilution partition coefficients, which can be used to determine how a dilute solute partitions between two solvents. Solutes were examined in three different liquid-liquid systems: water/n-hexane, water/acetonitrile, and water/n-octanol. With GCS, the average errors are 22% (for 18 solutes), 18% (for 14 solutes) and 14% (for 15 solutes) for these solvent systems, while comparable errors are 237%, 286% and 226% with UNIFAC; and 342%, 414% and 306% with modified UNIFAC. The GCS model is a powerful new tool to predict the octanol-water partition coefficients.

  19. 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…

  20. Effective charge measurements reveal selective and preferential accumulation of anions, but not cations, at the protein surface in dilute salt solutions

    PubMed Central

    Gokarn, Yatin R; Fesinmeyer, R Matthew; Saluja, Atul; Razinkov, Vladimir; Chase, Susan F; Laue, Thomas M; Brems, David N

    2011-01-01

    Specific-ion effects are ubiquitous in nature; however, their underlying mechanisms remain elusive. Although Hofmeister-ion effects on proteins are observed at higher (>0.3M) salt concentrations, in dilute (<0.1M) salt solutions nonspecific electrostatic screening is considered to be dominant. Here, using effective charge (Q*) measurements of hen-egg white lysozyme (HEWL) as a direct and differential measure of ion-association, we experimentally show that anions selectively and preferentially accumulate at the protein surface even at low (<100 mM) salt concentrations. At a given ion normality (50 mN), the HEWL Q* was dependent on anion, but not cation (Li+, Na+, K+, Rb+, Cs+, GdnH+, and Ca2+), identity. The Q* decreased in the order F− > Cl− > Br− > NO3− ∼ I− > SCN− > ClO4− ≫ SO42−, demonstrating progressively greater binding of the monovalent anions to HEWL and also show that the SO42− anion, despite being strongly hydrated, interacts directly with the HEWL surface. Under our experimental conditions, we observe a remarkable asymmetry between anions and cations in their interactions with the HEWL surface. PMID:21432935

  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. Temperature dependence of infinite dilution activity coefficients in octanol and octanol/water partition coefficients of some volatile halogenated organic compounds

    SciTech Connect

    Bhatai, S.R.; Sandler, S.I.

    1995-11-01

    The study of the fate and transport of volatile halogenated organic compounds in the environment is of interest as these chemicals, many of which have been classified as pollutants, are widely used as industrial solvents and are now appearing in water supplies. Infinite dilution activity coefficients and Henry`s law coefficients have been measured for 11 halogenated C{sub 1} to C{sub 3} compounds in 1-octanol above room temperature using a gas-liquid chromatographic measurement method. Then, using their earlier data for these substances in water and a correlation relating the limiting activity coefficients of a substance in pure water and in pure 1-octanol to their octanol/water partition coefficients, these latter quantities have been computed. One conclusion from these measurements is that the limiting activity coefficients in octanol and the octanol/water partition coefficients of the halogenated compounds studied are only weakly dependent on temperature over the range from 25 to 50 C. Also, from these and their earlier data, have estimated the infinite dilution partial molar excess enthalpies and excess entropies of these compounds in both 1-octanol and water.

  3. Characteristics of K+ and Rb+ as "structure-breaking" ions in dilute aqueous solution: Insights from ONIOM-XS MD simulations

    NASA Astrophysics Data System (ADS)

    Sripa, Pattrawan; Tongraar, Anan; Kerdcharoen, Teerakiat

    2016-11-01

    The structural and dynamical properties of the K+ and Rb+ hydrates have been investigated by means of the ONIOM-XS MD approach. For both the K+ and Rb+ hydrates, the ONIOM-XS MD results clearly reveal a high degree of flexibility within the first shell, with the average coordination numbers of 6.4 and 6.6, respectively. In this respect, it is observed that water molecules in the vicinity of K+ and Rb+ are rather labile, i.e., they are arranged with respect to the influence of the ion as well as to the hydrogen bond (HB) interactions among the first-shell waters and between the first-shell waters and the bulk. These observed phenomena clearly confirm the very loose first hydration shell of both the K+ and Rb+ ions, i.e., the weak ion-water interactions which correspond to the "structure-breaking" effects of K+ and Rb+ in aqueous solution.

  4. 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.

  5. 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.

  6. 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.

  7. Structural and Spectroscopic Properties of Water Around Small Hydrophobic Solutes

    PubMed Central

    Montagna, Maria; Sterpone, Fabio; Guidoni, Leonardo

    2013-01-01

    We investigated the structural, dynamical and spectroscopic properties of water molecules around a solvated methane by means of Car-Parrinello molecular dynamics simulations. Despite their mobility, in the first-shell water molecules are dynamically displaced in a clathrate-like cage around the hydrophobic solute. No significant differences in water geometrical parameters, in molecular dipole moments or in hydrogen bonding properties are observed between in-shell and out-shell molecules, indicating that liquid water can accommodate a small hydrophobic solute without altering its structural properties. The calculated contribution of the first shell water molecules to the infrared spectra does not show significant differences with respect the bulk signal once the effects of the missing polarization of second-shell molecules has been taken into account. Small fingerprints of the clathrate-like structure appear in the vibrational density of states in the libration and OH stretching regions. PMID:22946539

  8. Binary liquid phase separation and critical phenomena in a protein/water solution.

    PubMed Central

    Thomson, J A; Schurtenberger, P; Thurston, G M; Benedek, G B

    1987-01-01

    We have investigated the phase diagram of aqueous solutions of the bovine lens protein gamma II-crystallin. For temperatures T less than Tc = 278.5 K, we find that these solutions exhibit a reversible coexistence between two isotropic liquid phases differing in protein concentration. The dilute and concentrated branches of the coexistence curve were characterized, consistently, both by measurements of the two coexisting concentrations, c(T), and by measuring the cloud temperatures for various initial concentrations. We estimate that the critical concentration, cc, is 244 mg of protein per ml solution. The coexistence curve is well represented by the absolute value of (c - cc)/cc = 5.2 square root (Tc - T)/Tc. Using the temperature dependence of the scattered light intensity along isochores parallel to the critical isochore, we estimated the location of the spinodal line and found it to have the form (c - cc)/cc = 3.0 square root (Tc - T)/Tc. The ratio of the widths of the coexistence curve and the spinodal line, (5.2/3.0), is close to the mean-field value square root 3. We have also observed the growth of large crystals of gamma II-crystallin in some of these aqueous solutions and have made preliminary observations as to the factors that promote or delay the onset of crystallization. These findings suggest that selected protein/water systems can serve as excellent model systems for the study of phase transitions and critical phenomena. PMID:3478681

  9. 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.

  10. 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.

  11. MSWT-01, flood disaster water treatment solution from common ideas

    NASA Astrophysics Data System (ADS)

    Ananto, Gamawan; Setiawan, Albertus B.; Z, Darman M.

    2013-06-01

    Indonesia has a lot of potential flood disaster places with clean water problems faced. Various solution programs always initiated by Government, companies CSR, and people sporadical actions to provide clean water; with their advantages and disadvantages respectively. One solution is easy to operate for instance, but didn't provide adequate capacity, whereas the other had ideal performance but more costly. This situation inspired to develop a water treatment machine that could be an alternative favor. There are many methods could be choosed; whether in simple, middle or high technology, depends on water source input and output result quality. MSWT, Mobile Surface Water Treatment, is an idea for raw water in flood area, basically made for 1m3 per hour. This water treatment design adopted from combined existing technologies and related literatures. Using common ideas, the highlight is how to make such modular process put in compact design elegantly, and would be equipped with mobile feature due to make easier in operational. Through prototype level experiment trials, the machine is capable for producing clean water that suitable for sanitation and cooking/drinking purposes although using contaminated water input source. From the investment point of view, such machine could be also treated as an asset that will be used from time to time when needed, instead of made for project approach only.

  12. Anomalies in, and crystallization of supercooled water and aqueous solutions

    NASA Astrophysics Data System (ADS)

    Angell, C. A.

    1984-03-01

    This report summarizes research work performed under ONR auspices during the period 1978-1983. Thermodynamic studies of pure water and various aqueous solutions containing simple molecular second components such as H2O2N2H4 and formamide have been performed at temperatures down to -120 C, in order to perform extrapolations to obtain properties of normal water, i.e. water free from anomalous structure fluctuations. Properties studied have been heat capacity, expansivity and compressibility. On certain of these solutions, viscosity and also dielectric relaxation studies have been performed. Spectroscopic measurements in both the far infrared, and the near infrared, have yielded information on vibrational modes and characteristic hydrogen bonding structures. All together these measurements have done much to elucidate the anomalous behavior of water in the supercooled regime.

  13. Structural transformations, composition anomalies and a dramatic collapse of linear polymer chains in dilute ethanol-water mixtures.

    PubMed

    Banerjee, Saikat; Ghosh, Rikhia; Bagchi, Biman

    2012-03-29

    Water-ethanol mixtures exhibit many interesting anomalies, such as negative excess partial molar volume of ethanol, excess sound absorption coefficient at low concentrations, and positive deviation from Raoult's law for vapor pressure, to mention a few. These anomalies have been attributed to different, often contradictory origins, but a quantitative understanding is still lacking. We show by computer simulation and theoretical analyses that these anomalies arise from the sudden emergence of a bicontinuous phase that occurs at a relatively low ethanol concentration of x(eth) ≈ 0.06-0.10 (that amounts to a volume fraction of 0.17-0.26, which is a significant range!). The bicontinuous phase is formed by aggregation of ethanol molecules, resulting in a weak phase transition whose nature is elucidated. We find that the microheterogeneous structure of the mixture gives rise to a pronounced nonmonotonic composition dependence of local compressibility and nonmonotonic dependence in the peak value of the radial distribution function of ethyl groups. A multidimensional free energy surface of pair association is shown to provide a molecular explanation of the known negative excess partial volume of ethanol in terms of parallel orientation and hence better packing of the ethyl groups in the mixture due to hydrophobic interactions. The energy distribution of the ethanol molecules indicates additional energy decay channels that explain the excess sound attenuation coefficient in aqueous alcohol mixtures. We studied the dependence of the solvation of a linear polymer chain on the composition of the water-ethanol solvent. We find that there is a sudden collapse of the polymer at x(eth) ≈ 0.05-a phenomenon which we attribute to the formation of the microheterogeneous structures in the binary mixture at low ethanol concentrations. Together with recent single molecule pulling experiments, these results provide new insight into the behavior of polymer chain and foreign solutes

  14. 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

  15. Odor as an aid to chemical safety: odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution.

    PubMed

    Amoore, J E; Hautala, E

    1983-12-01

    The body of information in this paper is directed to specialists in industrial health and safety, and air and water pollution, who need quantitative data on the odor thresholds of potentially hazardous chemical vapors and gases. The literature, largely unorganized, has been reviewed for 214 compounds and condensed into tables based on consistent units. Data on the volatility, solubility, ionization and water-air distribution ratio at 25 degrees C are included. From the currently recommended threshold limit value (TLV), a safe dilution factor and an odor safety factor are calculated for each compound. The equivalent data are presented for both air and water dilutions of the chemicals. Available data are summarized on the variability of odor sensitivities in the population, and the increased odor concentrations that are required to elicit responses from persons whose attention is distracted, or who are sleeping. This information is reduced to calibration charts that may be used to estimate the relative detectability, warning potential and rousing capacity of the odorous vapors. Each compound has been assigned a letter classification, from A to E, to indicate the margin of safety, if any, that may be afforded by the odor of the compound as a warning that its threshold limit value is being exceeded.

  16. Dilution of /sup 210/Pb by organic sedimentation in lakes of different trophic states, and application to studies of sediment-water interactions

    SciTech Connect

    Binford, M.W.; Brenner, M.

    1986-05-01

    Lake sediments reflect conditions in the water column and can be used for rapid, integrative measurements of limnological variables. Examination of /sup 210/Pb-dated cores from 12 Florida lakes of widely differing trophic state (expressed as Carlson's trophic state index: TSI) shows that net accumulation rate of organic matter is related to primary productivity in the water column. In 26 other lakes the activity of unsupported /sup 210/Pb g/sup -1/ organic matter in surficial sediments is inversely related to trophic state and, therefore, to organic accumulation rate. From this observation, the authors develop a new method that uses fallout /sup 210/Pb as a dilution tracer to calculate net sedimentary accumulation rates of any material in surface mud. They demonstrate strong relationships between net loss rate of biologically important materials (C, N, P, and pigments) and their respective water concentrations (expressed as TSI). Multiple regression models incorporating net sediment accumulation rates of all four variables explain up to 70% of the lake-to-lake variation of TSI. The /sup 210/Pb-dilution method has application for studies for material cycling, paleolimnology, and sediment accumulation processes.

  17. 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.

  18. 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.

  19. 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.

  20. Probing the micro-phase separation of thermo-responsive amphiphilic polymer in water/ethanol solution.

    PubMed

    Labuta, Jan; Hill, Jonathan P; Hanyková, Lenka; Ishihara, Shinsuke; Ariga, Katsuhiko

    2010-12-01

    The temperature-induced coil-globule transition (micro-phase separation) in water/ethanol solutions of poly(vinyl methyl ether) was studied using NMR spectroscopy, differential scanning calorimetry, optical microscopy and dynamic light scattering. NMR sequence based on spin-echo was introduced in order to determine lower critical solution temperature with high accuracy. Variation in DSC profiles and enthalpy increments depending on ethanol concentration in a water/ethanol mixture was found. Evolution of morphology pattern during heating-cooling cycle was observed using optical microscopy. At lower PVME concentration the globule size distribution was determined using digital image processing. Relative number and relative mass size distributions of globules in a dilute sample were measured by differential scanning calorimetry and subsequently compared with those obtained by optical microscopy.

  1. Analysis of hydrazine in drinking water by isotope dilution gas chromatography/tandem mass spectrometry with derivatization and liquid-liquid extraction.

    PubMed

    Davis, William E; Li, Yongtao

    2008-07-15

    A new isotope dilution gas chromatography/chemical ionization/tandem mass spectrometric method was developed for the analysis of carcinogenic hydrazine in drinking water. The sample preparation was performed by using the optimized derivatization and multiple liquid-liquid extraction techniques. Using the direct aqueous-phase derivatization with acetone, hydrazine and isotopically labeled hydrazine-(15)N2 used as the surrogate standard formed acetone azine and acetone azine-(15)N2, respectively. These derivatives were then extracted with dichloromethane. Prior to analysis using methanol as the chemical ionization reagent gas, the extract was dried with anhydrous sodium sulfate, concentrated through evaporation, and then fortified with isotopically labeled N-nitrosodimethylamine-d6 used as the internal standard to quantify the extracted acetone azine-(15)N2. The extracted acetone azine was quantified against the extracted acetone azine-(15)N2. The isotope dilution standard calibration curve resulted in a linear regression correlation coefficient (R) of 0.999. The obtained method detection limit was 0.70 ng/L for hydrazine in reagent water samples, fortified at a concentration of 1.0 ng/L. For reagent water samples fortified at a concentration of 20.0 ng/L, the mean recoveries were 102% with a relative standard deviation of 13.7% for hydrazine and 106% with a relative standard deviation of 12.5% for hydrazine-(15)N2. Hydrazine at 0.5-2.6 ng/L was detected in 7 out of 13 chloraminated drinking water samples but was not detected in the rest of the chloraminated drinking water samples and the studied chlorinated drinking water sample.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. New Analytical Solution for Nonlinear Shallow Water-Wave Equations

    NASA Astrophysics Data System (ADS)

    Aydin, Baran; Kânoğlu, Utku

    2017-03-01

    We solve the nonlinear shallow water-wave equations over a linearly sloping beach as an initial-boundary value problem under general initial conditions, i.e., an initial wave profile with and without initial velocity. The methodology presented here is extremely simple and allows a solution in terms of eigenfunction expansion, avoiding integral transform techniques, which sometimes result in singular integrals. We estimate parameters, such as the temporal variations of the shoreline position and the depth-averaged velocity, compare with existing solutions, and observe perfect agreement with substantially less computational effort.

  8. Generation of acids from mine waste: Oxidative leaching of pyrrhotite in dilute H{sub 2}SO{sub 4} solutions at pH 3.0

    SciTech Connect

    Pratt, A.R.; Nesbitt, H.W.; Muir, I.J.

    1994-12-01

    Pyrrhotite (Fe{sub 7}S{sub 8}) grains 3 x 3 x 6 mm were reacted in solutions of H{sub 2}SO{sub 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 paragenetic alteration sequence. Leached pyrrhotite surfaces are initially featureless. Surfaces leached more extensively develop a mottled felty texture. Subsequent drying of reacted surfaces causes dehydration, producing cracked, tiled surfaces. Prolonged drying intensifies the effects of desiccation, producing rubbly textures. The rubble is readily spalled, exposing smooth underlayers. AES and XPS data collected from 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 acid-rich drainage waters.

  9. Fluxes of water and solute in a coastal wetland sediment. 2. Effect of macropores on solute exchange with surface water

    USGS Publications Warehouse

    Harvey, J.W.; Nuttle, W.K.

    1995-01-01

    Chloride was highly concentrated relative to seawater in matrix porewater but was comparatively dilute in macropores. Concentration differences in pore-size classes declined with depth until indistinguishable below 10 cm. The segregated chloride distribution can be explained if recharge to the sediment occurred by downward infiltration in macropores and discharge occurred by an upward flux in matrix pores to satisfy evapotranspiration. Without disturbance by the downward infiltration flux in macropores, upward advection of chloride in matrix pores and evapoconcentration increased chloride concentrations in matrix pores to a level well above the concentration in seawater. The resulting high concentrations of chloride in matrix pores induced a large diffusive efflux of chloride into surface water that was sufficient to balance new input of chloride by infiltration of seawater in macropores (0.085 mmol Cl cm -2 day-1). Transport models that were constrained by water balance measurements at the field site explained both the exponential form of the vertical distribution of chloride in matrix pores and the rate of change in storage of chloride in sediment porewater over a one month period. -from Authors

  10. 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.

  11. THE VAPOUR PRESSURES OF AQUEOUS SOLUTIONS WITH SPECIAL REFERENCE TO THE PROBLEM OF THE STATE OF WATER IN BIOLOGICAL FLUIDS

    PubMed Central

    Grollman, Arthur

    1931-01-01

    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, CaCl2 (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 CaCl2—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. PMID:19872614

  12. Effects of diaphragm discharge in water solutions containing humic substances

    NASA Astrophysics Data System (ADS)

    Halamova, Ivana; Stara, Zdenka; Krcma, Frantisek

    2010-01-01

    Preliminary results of research focused on the applications of DC diaphragm discharge in water solutions containing humic substances are presented in this paper. Diaphragm discharge investigated by this work was created in the reactor using constant DC high voltage up to 2 kV that gave the total input power from 100 to 200 W. Presented work investigated decomposition of humic substances by the electric discharge in the dependence of discharge conditions (electrode polarity) as well as solution properties (electrolyte kind, pH). Especially substantial effect of pH on humic acid decomposition has been observed when acidic conditions stimulated the degradation process. Absorption spectroscopy in UV-VIS region together with fluorescence spectroscopy has been used for the detection of changes in humic solutions. Index of humification was calculated from obtained fluorescence spectra and a significant decrease of aromatic components in the humic mixture was determined during the discharge treatment.

  13. Pressure induced breather overturning on deep water: Exact solution

    NASA Astrophysics Data System (ADS)

    Abrashkin, A. A.; Oshmarina, O. E.

    2014-08-01

    A vortical model of breather overturning on deep water is proposed. The action of wind is simulated by nonuniform pressure on the free surface. The fluid motion is described by an exact solution of 2D hydrodynamic equations for an inviscid fluid in Lagrangian variables. Fluid particles rotate in circles of different radii. Formation of contraflexure points on the breather profile is studied. The mechanism of wave breaking and the role of flow vorticity are discussed.

  14. Short-Chain Polysaccharide Analysis in Ethanol-Water Solutions.

    PubMed

    Yan, Xun

    2017-03-01

    This study demonstrates that short-chain polysaccharides, or oligosaccharides, could be sufficiently separated with hydrophilic interaction LC (HILIC) conditions and quantified by evaporative light-scattering detection (ELSD). The multianalyte calibration approach improved the efficiency of calibrating the nonlinear detector response. The method allowed easy quantification of short-chain carbohydrates. Using the HILIC method, the oligosaccharide solubility and its profile in water/alcohol solutions at room temperature were able to be quantified. The results showed that the polysaccharide solubility in ethanol–water solutions decreased as ethanol content increased. The results also showed oligosaccharides to have minimal solubility in pure ethanol. In a saturated maltodextrin ethanol (80%) solution, oligosaccharide components with a degree of polymerization >12 were practically insoluble and contributed less than 0.2% to the total solute dry weight. The HILIC–ELSD method allows for the identification and quantification of low-MW carbohydrates individually and served as an alternative method to current gel permeation chromatography procedures.

  15. Description of Hydration Water in Protein (Green Fluorescent Protein) Solution

    SciTech Connect

    Perticaroli, Stefania; Ehlers, Georg; Stanley, Christopher B.; Mamontov, Eugene; O’Neill, Hugh; Zhang, Qiu; Cheng, Xiaolin; Myles, Dean A. A.; Katsaras, John; Nickels, Jonathan D.

    2016-10-26

    The structurally and dynamically perturbed hydration shells that surround proteins and biomolecules have a substantial influence upon their function and stability. This makes the extent and degree of water perturbation of practical interest for general biological study and industrial formulation. Here, we present an experimental description of the dynamical perturbation of hydration water around green fluorescent protein in solution. Less than two shells (~5.5 Å) were perturbed, with dynamics a factor of 2–10 times slower than bulk water, depending on their distance from the protein surface and the probe length of the measurement. Furthermore, this dependence on probe length demonstrates that hydration water undergoes subdiffusive motions (τ ∝ q–2.5 for the first hydration shell, τ ∝ q–2.3 for perturbed water in the second shell), an important difference with neat water, which demonstrates diffusive behavior (τ ∝ q–2). Our results help clarify the seemingly conflicting range of values reported for hydration water retardation as a logical consequence of the different length scales probed by the analytical techniques used.

  16. Description of Hydration Water in Protein (Green Fluorescent Protein) Solution

    DOE PAGES

    Perticaroli, Stefania; Ehlers, Georg; Stanley, Christopher B.; ...

    2016-10-26

    The structurally and dynamically perturbed hydration shells that surround proteins and biomolecules have a substantial influence upon their function and stability. This makes the extent and degree of water perturbation of practical interest for general biological study and industrial formulation. Here, we present an experimental description of the dynamical perturbation of hydration water around green fluorescent protein in solution. Less than two shells (~5.5 Å) were perturbed, with dynamics a factor of 2–10 times slower than bulk water, depending on their distance from the protein surface and the probe length of the measurement. Furthermore, this dependence on probe length demonstratesmore » that hydration water undergoes subdiffusive motions (τ ∝ q–2.5 for the first hydration shell, τ ∝ q–2.3 for perturbed water in the second shell), an important difference with neat water, which demonstrates diffusive behavior (τ ∝ q–2). Our results help clarify the seemingly conflicting range of values reported for hydration water retardation as a logical consequence of the different length scales probed by the analytical techniques used.« less

  17. Maximum First Transfer and Dilution Volumes for 241SY101

    SciTech Connect

    BARTON, W.B.

    1999-10-28

    This report discusses the solution to the following problem: what is the maximum waste transfer and dilution quantities and locations which can be allowed in the first transfer of waste from SY-101 given the following constraints? (1) The crust must float on the submerged waste (waste becomes less dense when diluted, eventually allowing crust to sink); (2) No credit is taken for the top dilution; (3) Addition of water to the bulk slurry through the transfer pump must be able to refloat the crust base to above 295 inches; (4) The margin between refloating to 295 inches and crust sinking must be at least 10,000 gallons; (5) The crust can't be thinned to less than 60 inches thick.

  18. 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.

  19. Ultrasonic speed, densities and viscosities of xylitol in water and in aqueous tyrosine and phenylalanine solutions at different temperatures

    NASA Astrophysics Data System (ADS)

    Ali, A.; Bidhuri, P.; Uzair, S.

    2014-07-01

    Ultrasonic speed u, densities ρ and viscosities η of xylitol in water and in 0.001 m aqueous l-tyrosine (Tyr) and l-phenylalanine (Phe) have been measured at different temperatures. From the density and ultrasonic speed measurements apparent molar isentropic compression κ_{φ}, apparent molar isentropic compressions at infinite dilution κ_{{S,φ}}0 , experimental slope S K , hydration number n H , transfer partial molar isentropic compressibility Δ_{tr} κ_{{S,φ}}0 of xylitol from water to aqueous Tyr and Phe have been obtained. From the viscosity data, B-coefficient and B-coefficient of transfer Δ tr B of xylitol from water to aqueous Phe and Tyr at different temperatures have also been estimated. Gibbs free energies of activation of viscous flow per mole of solvent Δ μ 1 0# and per mole of solute Δ μ 2 0# have been calculated by using Feakins transition state theory for the studied systems. The calculated parameters have been interpreted in terms of solute-solute and solute-solvent interactions and hydration behavior of xylitol.

  20. What happens to the structure of water in cryoprotectant solutions?

    PubMed

    Towey, James J; Soper, Alan K; Dougan, Lorna

    2013-01-01

    Cryoprotectant molecules are widely utilised in basic molecular research through to industrial and biomedical applications. The molecular mechanisms by which cryoprotectants stabilise and protect molecules and cells, along with suppressing the formation of ice, are incompletely understood. To gain greater insight into these mechanisms, we have completed an experimental determination of the structure of aqueous glycerol. Our investigation combines neutron diffraction experiments with isotopic substitution and computational modelling to determine the atomistic level structure of the glycerol-water mixtures, across the complete concentration range at room temperature. We examine the local structure of the system focusing on water structure. By comparing our data with that from other studies of cryoprotectant solutions, we attempt to find general rules for the action of cryoprotectants on water structure. We also discuss how these molecular scale interactions may be related to the macroscopic properties of the system.

  1. ISOTOPE DILUTION ANALYSIS OF BROMATE IN DRINKING WATER MATRIXES BY ION CHROMATOGRAPHY WITH INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRIC DETECTION

    EPA Science Inventory

    Bromate is a disinfection byproduct in drinking water which is formed during the ozonation of source water containing bromide. This paper described the analysis of bromate via ion chromatography-inductively coupled plasma mass spectrometry. The separation of bromate from interfer...

  2. Is the solution activity derivative sufficient to parameterize ion-ion interactions in aqueous solution?-ions for TIP5P water.

    PubMed

    Satarifard, Vahid; Kashefolgheta, Sadra; Vila Verde, Ana; Grafmueller, Andrea

    2017-04-10

    Biomolecular processes involve hydrated ions, and thus molecular simulations of such processes require accurate force-field parameters for these ions. In the best force-fields, both ion-water and anion-cation interactions are explicitly parameterized. First, the ion Lennard-Jones parameters are optimized to reproduce, e.g., single ion solvation free energies; then ion-pair interactions are often adjusted to match experimental activity or activity derivatives. Here we apply this approach to derive optimized parameters for concentrated NaCl, KCl, MgCl2 and CaCl2 salt solutions, to be used with the TIP5P water model. These parameters are of interest because of a number of desirable properties of the TIP5P water model, especially for the simulation of carbohydrates. The results show, that this approach is insufficient, because the activity derivative often reaches a plateau near the target experimental value, for a wide range of parameter values. The plateau emerges from the interconversion between different types of ion pairs, so parameters leading to equally good agreement with the target solution activity or activity derivative yield very different solution structures. To resolve this indetermination, a second target property, such as the experimentally determined ion-ion coordination number, is required to uniquely determine anion-cation interactions. Simulations show that combining activity derivatives and coordination number as experimental target properties to parameterize ion-ion interactions, is a powerful method for reliable ion-water force field parameterization, and gives insight into the concentration of contact or solvent shared ion pairs in a wide range of salt concentrations. For the alkali and halide ions Li(+), Rb(+), Cs(+), F(-), Br(-), I(-), we present ion-water parameters appropriate at infinite dilution only.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Organic solute profile of water from Rio Blanco Retort 1

    SciTech Connect

    Poulson, R.E.; Clark, J.A.; Borg, H.M.

    1985-12-01

    Two water samples were taken from the Rio Blanco Oil Shale Company's Retort 1 more than three years after shutdown of the retort burn. The retort had received considerable flushing. These water samples were screened and profiled chromatographically to ascertain the character of the 20 to 30 ppM total organic carbon remaining in each. The waters were found to contain only organophilic solutes above the one-part-per-billion level. Special detection methods with part-per-billion detection limits for selected hydrophilic indicators proved negative for those indicators. Selected indicators ranged from the most hydrophilic (alkanoic acids, alkylamines, and amides) to the least (phenol). The principal species readily identified by either gas chromatography or reversed-phase liquid chromatography were the light polyalkylpyridines and the polyalkylphenols. The two principal individual compounds detected in each water were 2,4,6-trimethylpyridine and 2,3,5-trimethylphenol. The approximate concentrations of each were 200 ppb for a sample taken from the retort center and 400 ppb for a sample taken from the bottom level. It appears that there is a residual oil reservoir in the retort serving as a source of organophilic solutes. Any organic material now passing out of the retort would be highly organophilic and predisposed to deposit on even slightly hydrophobic surfaces such as oil shale or retorted oil shale. Based on the observations in this report, hydrophilic organic solutes may be presumed to be the key indicators for the interaction between oil shale in situ retort effluent and the surrounding environment. Timely monitoring of such sites and development of highly sensitive detection techniques for this class of materials would permit accurate description of migration pathways. 9 refs., 5 figs., 1 tab.

  8. 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.

  9. Removal of Metal Nanoparticles Colloidal Solutions by Water Plants

    NASA Astrophysics Data System (ADS)

    Olkhovych, Olga; Svietlova, Nataliia; Konotop, Yevheniia; Karaushu, Olena; Hrechishkina, Svitlana

    2016-11-01

    The ability of seven species of aquatic plants ( Elodea canadensis, Najas guadelupensis, Vallisneria spiralis L., Riccia fluitans L., Limnobium laevigatum, Pistia stratiotes L., and Salvinia natans L.) to absorb metal nanoparticles from colloidal solutions was studied. It was established that investigated aquatic plants have a high capacity for removal of metal nanoparticles from aqueous solution (30-100%) which indicates their high phytoremediation potential. Analysis of the water samples content for elements including the mixture of colloidal solutions of metal nanoparticles (Mn, Cu, Zn, Ag + Ag2O) before and after exposure to plants showed no significant differences when using submerged or free-floating hydrophytes so-called pleuston. However, it was found that the presence of submerged hydrophytes in aqueous medium ( E. canadensis, N. guadelupensis, V. spiralis L., and R. fluitans L.) and significant changes in the content of photosynthetic pigments, unlike free-floating hydrophytes ( L. laevigatum, P. stratiotes L., S. natans L.), had occur. Pleuston possesses higher potential for phytoremediation of contaminated water basins polluted by metal nanoparticles. In terms of removal of nanoparticles among studied free-floating hydrophytes, P. stratiotes L. and S. natans L. deserve on special attention.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Hairpin ribozyme-catalyzed ligation in water-alcohol solutions.

    PubMed

    Vlassov, Alexander V; Johnston, Brian H; Kazakov, Sergei A

    2005-12-01

    The hairpin ribozyme (HPR) is a naturally existing RNA that catalyzes site-specific RNA cleavage and ligation. At 37 degrees C and in the presence of divalent metal ions (M(2+)), the HPR efficiently cleaves RNA substrates in trans. Here, we show that the HPR can catalyze efficient M(2+)-independent ligation in trans in aqueous solutions containing any of several alcohols, including methanol, ethanol, and isopropanol, and millimolar concentrations of monovalent cations. Ligation proceeds most efficiently in 60% isopropanol at 37 degrees C, whereas the reverse (cleavage) reaction is negligible under these conditions. We suggest that dehydration of the RNA is the key factor promoting HPR activity in water- alcohol solutions. Alcohol-induced ribozyme ligation may have practical applications.

  15. Dilutions Made Easy.

    ERIC Educational Resources Information Center

    Kamin, Lawrence

    1996-01-01

    Presents problems appropriate for high school and college students that highlight dilution methods. Promotes an understanding of dilution methods in order to prevent the unnecessary waste of chemicals and glassware in biology laboratories. (JRH)

  16. High-dilution effects revisited. 2. Pharmacodynamic mechanisms.

    PubMed

    Bellavite, Paolo; Marzotto, Marta; Olioso, Debora; Moratti, Elisabetta; Conforti, Anita

    2014-01-01

    The pharmacodynamics aspects of homeopathic remedies are appraised by laboratory studies on the biological effects at various levels (cellular, molecular and systemic). The major question is how these medicines may work in the body. The possible answers concern the identification of biological targets, the means of drug-receptor interactions, the mechanisms of signal transmission and amplification, and the models of inversion of effects according to the traditional 'simile' rule. These problems are handled by two experimental and theoretical lines, according to the doses or dilutions considered (low-medium versus high dilutions). Homeopathic formulations in low-medium dilutions, containing molecules in the range of ultra-low doses, exploit the extreme sensitivity of biological systems to exogenous and endogenous signals. Their effects are interpreted in the framework of hormesis theories and paradoxical pharmacology. The hypotheses regarding the action mechanisms of highly diluted/dynamized solutions (beyond Avogadro-Loschmidt limit) variously invoke sensitivity to bioelectromagnetic information, participation of water chains in signalling, and regulation of bifurcation points of systemic networks. High-dilution pharmacology is emerging as a pioneering subject in the domain of nanomedicine and is providing greater plausibility to the puzzling claims of homeopathy.

  17. 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.

  18. 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.

  19. Isotope dilution high-resolution gas chromatography/high-resolution mass spectrometry method for analysis of selected acidic herbicides in surface water.

    PubMed

    Woudneh, Million B; Sekela, Mark; Tuominen, Taina; Gledhill, Melissa

    2006-11-10

    In this work, an isotope dilution method for determination of selected acidic herbicides by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) was developed for surface water samples. Average percent recoveries of native analytes were observed to be between 70.8 and 93.5% and average recoveries of labeled quantification standards [(13)C(6)]2,4-D and [(13)C(6)]2,4,5-T were 85.5 and 101%, respectively. Using this method, detection limits of 0.05 ng/L for dicamba, MCPA, MCPP, and triclopyr, and 0.5 ng/L for 2,4-D were routinely achieved. The method was applied to measuring the concentration of these analytes in surface water samples collected from five sampling locations in the Lower Fraser Valley region of British Columbia, Canada. All of the herbicides monitored were detected at varying levels in the surface water samples collected. The highest concentrations detected for each analyte were 345 ng/L for 2,4-D, 317 ng/L for MCPA, 271 ng/L for MCPP, 15.7 ng/L for dicamba, and 2.18 ng/L for triclopyr. Average detection frequencies of the herbicides were 95% for MCPA, 80% for MCPP, 70% for dicamba, 65% for 2,4-D, and 46% for triclopyr. Seasonal variations of herbicide levels are also discussed.

  20. An outbreak of Burkholderia cenocepacia associated with contaminated chlorhexidine solutions prepared in the hospital.

    PubMed

    Lee, Shinwon; Han, Seung Woo; Kim, Gunwoo; Song, Do Young; Lee, Je Chul; Kwon, Ki Tae

    2013-09-01

    From October to December 2007, an outbreak of Burkholderia cenocepacia occurred in a secondary care hospital. The 19 B cenocepacia isolated from the patients, the chlorhexidine solutions of each different ward, and the purified water that diluted these solutions exhibited an identical pulsed-field gel electrophoresis pattern. Inadequate preparation of chlorhexidine solutions diluted with contaminated purified water may have resulted in an outbreak of B cenocepacia. Adequate preparation of chlorhexidine solutions should be emphasized.

  1. 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

  2. Characteristics of hydration water around hen egg lysozyme as the protein model in aqueous solution. FTIR spectroscopy and molecular dynamics simulation.

    PubMed

    Panuszko, Aneta; Wojciechowski, Marek; Bruździak, Piotr; Rakowska, Paulina W; Stangret, Janusz

    2012-12-05

    In this paper, the hydration of a model protein--hen egg white lysozyme in aqueous solution has been presented. The leading method used was FTIR spectroscopy with an application of a technique of semi-heavy water (HDO) isotope dilution. Analysis of spectra of HDO isotopically diluted in water solution of lysozyme allowed us to isolate HDO spectra affected by lysozyme, and thus to characterise the energetic state of water molecules and their arrangement around protein molecules. The number of water molecules and the shape of the affected HDO spectrum were obtained using a classical and a chemometric method. This shape showed that the HDO spectrum affected by lysozyme may be presented as a superposition of two spectra corresponding to HDO affected by N-methylacetamide and the carboxylate anion (of the formic acid). Moreover, based on the difference in intermolecular distances distribution of water molecules (obtained from spectral data), we demonstrated that the lysozyme molecule causes a decrease in population of weak hydrogen bonds, and concurrently increases the probability of an occurrence of short hydrogen bonds in water affected by lysozyme. This conclusion was also confirmed by the molecular dynamics (MD) simulation.

  3. 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.

  4. 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.

  5. Dilution and volatilization of groundwater contaminant discharges in streams.

    PubMed

    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.

  6. Bubble Dynamics in Polymer Solutions Undergoing Shear.

    DTIC Science & Technology

    1985-04-01

    20D 23 REYNOLDS NUMBER *10’ FIGURE 1-1. The effect of dilute polymer solutes on hydraulic cavitation inception (Ellis &Ting, 1974). (a) ( b ) FIGURE 1-2...Comparison of cavitation appearance in (a) water and ( b ) dilute aqueous Polyox solution (Ting, 1978). 3 cavitation is significantly altered (Figure...research fall into two distinct (but related) areas. These are (a) Newtonian (or viscous) flow-induced cavitation bubble deformation and ( b ) non

  7. Effective pretreatment of dilute NaOH-soaked chestnut shell with glycerol-HClO4-water media: structural characterization, enzymatic saccharification, and ethanol fermentation.

    PubMed

    He, Yu-Cai; Liu, Feng; Di, Jun-Hua; Ding, Yun; Gao, Da-Zhou; Zhang, Dan-Ping; Tao, Zhi-Cheng; Chong, Gang-Gang; Huang, Mei-Zi; Ma, Cui-Luan

    2016-04-01

    In this study, an effective pretreatment of dilute NaOH-soaked chestnut shell (CNS) with glycerol-HClO4-water (88.8:1.2:10, w/w/w) media at 130 °C for 30 min was successfully demonstrated. Results revealed that the combination pretreatment removed 66.0 % of lignin and 73.7 % of hemicellulose in untreated CNS. The changes in the structural features (crystallinity, morphology, and porosity) of the solid residue of CNS were characterized with Fourier transform infrared spectroscopy, fluorescent microscope, scanning electron microscopy, and X-ray diffraction. Biotransformation of glycerol-HClO4-water pretreated-NaOH-soaked CNS (50 g/L) with a cocktail of enzymes for 72 h, the reducing sugars and glucose were 39.7 and 33.4 g/L, respectively. Moreover, the recovered hydrolyzates containing 20 g/L glucose had no inhibitory effects on the ethanol-fermenting microorganism, and the ethanol production was 0.45 g/g glucose within 48 h. In conclusion, this combination pretreatment shows promise as pretreatment solvent for wheat straw, although the in-depth exploration of this subject is needed.

  8. 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.

  9. Simultaneous determination of PPCPs, EDCs, and artificial sweeteners in environmental water samples using a single-step SPE coupled with HPLC-MS/MS and isotope dilution.

    PubMed

    Tran, Ngoc Han; Hu, Jiangyong; Ong, Say Leong

    2013-09-15

    A high-throughput method for the simultaneous determination of 24 pharmaceuticals and personal care products (PPCPs), endocrine disrupting chemicals (EDCs) and artificial sweeteners (ASs) was developed. The method was based on a single-step solid phase extraction (SPE) coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and isotope dilution. In this study, a single-step SPE procedure was optimized for simultaneous extraction of all target analytes. Good recoveries (≥ 70%) were observed for all target analytes when extraction was performed using Chromabond(®) HR-X (500 mg, 6 mL) cartridges under acidic condition (pH 2). HPLC-MS/MS parameters were optimized for the simultaneous analysis of 24 PPCPs, EDCs and ASs in a single injection. Quantification was performed by using 13 isotopically labeled internal standards (ILIS), which allows correcting efficiently the loss of the analytes during SPE procedure, matrix effects during HPLC-MS/MS and fluctuation in MS/MS signal intensity due to instrument. Method quantification limit (MQL) for most of the target analytes was below 10 ng/L in all water samples. The method was successfully applied for the simultaneous determination of PPCPs, EDCs and ASs in raw wastewater, surface water and groundwater samples collected in a local catchment area in Singapore. In conclusion, the developed method provided a valuable tool for investigating the occurrence, behavior, transport, and the fate of PPCPs, EDCs and ASs in the aquatic environment.

  10. 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.

  11. 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.

  12. 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.

  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. 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

  15. 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.

  16. 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

  17. 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...

  18. 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 ...

  19. The decisive role of free water in determining homogenous ice nucleation behavior of aqueous solutions.

    PubMed

    Wang, Qiang; Zhao, Lishan; Li, Chenxi; Cao, Zexian

    2016-05-26

    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.

  20. 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

  1. A solution to water vapor in the National Transonic Facility

    NASA Technical Reports Server (NTRS)

    Gloss, Blair B.; Bruce, Robert A.

    1989-01-01

    As cryogenic wind tunnels are utilized, problems associated with the low temperature environment are being discovered and solved. Recently, water vapor contamination was discovered in the National Transonic Facility, and the source was shown to be the internal insulation which is a closed-cell polyisocyanurate foam. After an extensive study of the absorptivity characteristics of the NTF thermal insulation, the most practical solution to the problem was shown to be the maintaining of a dry environment in the circuit at all times. Utilizing a high aspect ratio transport model, it was shown that the moisture contamination effects on the supercritical wing pressure distributions were within the accuracy of setting test conditions and as such were considered negligible for this model.

  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. Microfluidic serial dilution ladder.

    PubMed

    Ahrar, Siavash; Hwang, Michelle; Duncan, Philip N; Hui, Elliot E

    2014-01-07

    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).

  4. 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.

  5. 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.

  6. 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

  7. Excited-state dynamics of rhodamine 6G in aqueous solution and at the dodecane/water interface.

    PubMed

    Fedoseeva, Marina; Letrun, Romain; Vauthey, Eric

    2014-05-15

    The excited-state dynamics of rhodamine 6G (R6G) has been investigated in aqueous solution using ultrafast transient absorption spectroscopy and at the dodecane/water interface using the femtosecond time-resolved surface second harmonic generation (SSHG) technique. As the R6G concentration exceeds ca. 1 mM in bulk water, both R6G monomers and aggregates are excited to a different extent when using pump pulses at 500 and 530 nm. The excited-state lifetime of the monomers is shortened compared to dilute solutions because of the occurrence of excitation energy transfer to the aggregates, which themselves decay nonradiatively to the ground state with a ca. 70 ps time constant. At the dodecane/water interface, both monomers and aggregates contribute to the SSHG signal to an extent that depends on the bulk concentration, the pump and probe wavelengths, and the polarization of probe and signal beams. The excited-state lifetime of the monomers at the interface is of the order of a few picoseconds even at bulk concentrations where it is as large as several nanoseconds. This is explained by the relatively high interfacial affinity of R6G that leads to a large interfacial concentration, favoring aggregation and thus rapid excitation energy transfer from monomers to aggregates.

  8. 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

  9. Heat capacities of aqueous solutions of sodium hydroxide and water ionization up to 300 °C at 10 MPa

    NASA Astrophysics Data System (ADS)

    Schrödle, Simon; Königsberger, Erich; May, Peter M.; Hefter, Glenn

    2008-07-01

    A commercial (Setaram C80) calorimeter has been modified to measure the heat capacities of highly caustic solutions at temperatures up to 300 °C and pressures up to 20 MPa. The improvements have allowed more accurate determination of the isobaric volumetric heat capacities of chemically aggressive liquids at high temperatures. Test measurements with aqueous solutions of sodium chloride showed a reproducibility of about ±0.1%, with an accuracy of ˜0.3% or better, over the whole temperature range. Heat capacities of aqueous solutions of sodium hydroxide at concentrations from 0.5 to 8 mol/kg were measured at temperatures from 50 to 300 °C and a pressure of 10 MPa. Apparent molar isobaric heat capacities of NaOH(aq) were calculated using densities determined previously for the same solutions by vibrating-tube densimetry. Standard state (infinite dilution) partial molar isobaric heat capacities of NaOH(aq) were obtained by extrapolation using an extended Redlich-Meyer equation. Values of the standard heat capacity change for the ionization of water up to 300 °C were derived by combining the present results with the literature data for HCl(aq) and NaCl(aq).

  10. Effect of soaking in water and rumen digeta solutions on metabolizable energy content and chemical composition of barley seeds for use in poultry diet.

    PubMed

    Tabatabee, S N; Sadeghi, G H; Tabeidian, S A

    2007-03-15

    An experiment was carried out to evaluate the effect of soaking in water and different rumen digesta solutions on nutritional value of dry barley seeds. Treatments were included distilled water as control and rumen digesta that diluted with distilled water to obtain 20, 40 and 60% digesta solutions. Solutions have added to 10 kg of barley seed samples to achieve final 30% moisture content. After 21 days the chemical composition and energy content of barley seed were determined. Gross energy of barley seeds did not affected by different experimental treatments. Use of 20% rumen digesta solution resulted to a significant (p<0.01) increase in AME and AMEn content of barley seeds. Barley seed that treated with 40% of rumen digesta solution had highest TME and TMEn content and its different from seeds that treated with 60 and 100% rumen digesta solutions was significant (p<0.05). The chemical composition such as dry matter, crud protein, crude fat, crud fiber, ash and NFE were found to be similar and there was no significant difference. However, soaking in rumen digesta solutions increased crud protein, ether extract, crude fiber and ash content of barley seeds numerically.

  11. River Restoration Within Water Supply Areas - Problems and Solution Approaches

    NASA Astrophysics Data System (ADS)

    Regli, C.; Huggenberger, P.; Guldenfels, L.

    2004-05-01

    The demand of river restoration in many areas of Europe and North America clarifies the existing problems of a sustainable use of water resources. River restoration generally intensifies the exchange between surface- and groundwater and related dissolved compounds or particles. Recommendations concerning ecological measures of river restoration within water supply areas should allow differentiated solutions, which take into account groundwater and flood protection. Model scenarios play an important role in decision-making processes. An application of this approach is given for the groundwater production system of the city of Basel, Switzerland: The former channelized river Wiese should be restored to more natural conditions to re-establish the biological connectivity and to increase the recreational value of this area. These initiatives might conflict with the requirements of groundwater protection, especially during flood events. Therefore, processes of river-groundwater interaction have been characterized by analyses of physical, chemical, and microbiological data sampled in several well clusters between the river and production wells. The well clusters allow sampling of groundwater in different depths of the aquifer. These data together with data from tracer experiments are used for modeling the river-groundwater interaction. The large- and medium-scaled, transient groundwater models are used to evaluate the well capture zones in the different river restoration scenarios. Well capture zones have to satisfy the safety requirements of groundwater protection. A further step includes optimizations of water supply operation such as artificial recharge and pumping. At the small scale, uncertainty estimations concerning delineation of well capture zones are made by stochastic approaches including geological and geophysical data of the aquifer. The methods presented can be used to define and evaluate groundwater protection zones in heterogeneous aquifers associated with

  12. 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

  13. 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.

  14. 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%.

  15. 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.

  16. Insights into the effect of dilute acid, hot water and alkaline pretreatment on cellulose accessible surface area and overall porosity of Populus

    DOE PAGES

    Meng, Xianzhi; Wells, Tyrone; Sun, Qining; ...

    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

  17. Headspace solid phase microextraction and gas chromatography-olfactometry dilution analysis of young and aged Chinese "Yanghe Daqu" liquors.

    PubMed

    Fan, Wenlai; Qian, Michael C

    2005-10-05

    The aroma compounds of young and aged Chinese "Yanghe Daqu" liquor samples were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography (GC)-olfactometry dilution analysis. The original liquor samples were diluted with deionized water to give a final alcohol content of 14% (v/v). The samples were stepwise diluted (1:1) with 14% (by volume) ethanol-water solution and then extracted by headspace SPME. The samples were preequilibrated at 50 degrees C for 15 min and extracted with stirring at the same temperature for 30 min prior to injection into GC. The aroma compounds were identified by both GC-MS and GC-olfactometry using DB-Wax and DB-5 columns. The results suggested that esters were the major contributors to Yanghe Daqu liquor aroma. Ethyl hexanoate, ethyl butanoate, and ethyl pentanoate had very high flavor dilution values in both young and aged liquors (FD > 8192). Methyl hexanoate, ethyl heptanoate, ethyl benzoate, and butyl hexanoate could also be very important because of their high flavor dilution values (FD > or = 256). Moreover, two acetals, 1,1-diethoxyethane and 1,1-diethoxy-3-methylbutane, also were shown high flavor dilution values in Yanghe Daqu liquors (FD > or = 256). Other aroma compounds having moderate flavor dilution values included acetaldehyde, 3-methylbutanol, and 2-pentanol (FD > or = 32). Comparing young and aged liquors, the aroma profiles were similar, but the aroma compounds in the aged sample had higher flavor dilution values than in the young ones.

  18. 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.

  19. 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.

  20. Potential of the octanol-water partition coefficient (logP) to predict the dermal penetration behaviour of amphiphilic compounds in aqueous solutions.

    PubMed

    Korinth, Gintautas; Wellner, Tanja; Schaller, Karl Heinz; Drexler, Hans

    2012-11-23

    Aqueous amphiphilic compounds may exhibit enhanced skin penetration compared with neat compounds. Conventional models do not predict this percutaneous penetration behaviour. We investigated the potential of the octanol-water partition coefficient (logP) to predict dermal fluxes for eight compounds applied neat and as 50% aqueous solutions in diffusion cell experiments using human skin. Data for seven other compounds were accessed from literature. In total, seven glycol ethers, three alcohols, two glycols, and three other chemicals were considered. Of these 15 compounds, 10 penetrated faster through the skin as aqueous solutions than as neat compounds. The other five compounds exhibited larger fluxes as neat applications. For 13 of the 15 compounds, a consistent relationship was identified between the percutaneous penetration behaviour and the logP. Compared with the neat applications, positive logP were associated with larger fluxes for eight of the diluted compounds, and negative logP were associated with smaller fluxes for five of the diluted compounds. Our study demonstrates that decreases or enhancements in dermal penetration upon aqueous dilution can be predicted for many compounds from the sign of logP (i.e., positive or negative). This approach may be suitable as a first approximation in risk assessments of dermal exposure.

  1. Analysis of nitrosamines in water by automated SPE and isotope dilution GC/HRMS Occurrence in the different steps of a drinking water treatment plant, and in chlorinated samples from a reservoir and a sewage treatment plant effluent.

    PubMed

    Planas, Carles; Palacios, Oscar; Ventura, Francesc; Rivera, Josep; Caixach, Josep

    2008-08-15

    A method based on automated solid-phase extraction (SPE) and isotope dilution gas chromatography/high resolution mass spectrometry (GC/HRMS) has been developed for the analysis of nine nitrosamines in water samples. The combination of automated SPE and GC/HRMS for the analysis of nitrosamines has not been reported previously. The method shows as advantages the selectivity and sensitivity of GC/HRMS analysis and the high efficiency of automated SPE with coconut charcoal EPA 521 cartridges. Low method detection limits (MDLs) were achieved, along with a greater facility of the procedure and less dependence on the operator with regard to the methods based on manual SPE. Quality requirements for isotope dilution-based methods were accomplished for most analysed nitrosamines, regarding to trueness (80-120%), method precision (<15%) and MDLs (0.08-1.7 ng/L). Nineteen water samples (16 samples from a drinking water treatment plant {DWTP}, 2 chlorinated samples from a sewage treatment plant {STP} effluent, and 1 chlorinated sample from a reservoir) were analysed. Concentrations of nitrosamines in the STP effluent were 309.4 and 730.2 ng/L, being higher when higher doses of chlorine were applied. N-Nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were the main compounds identified in the STP effluent, and NDEA was detected above 200 ng/L, regulatory level for NDMA in effluents stated in Ontario (Canada). Lower concentrations of nitrosamines were found in the reservoir (20.3 ng/L) and in the DWTP samples (n.d. -28.6 ng/L). NDMA and NDEA were respectively found in the reservoir and in treated and highly chlorinated DWTP samples at concentrations above 10 ng/L (guide value established in different countries). The highest concentrations of nitrosamines were found after chlorination and ozonation processes (ozonated, treated and highly chlorinated water) in DWTP samples.

  2. Stability and mobility of small vacancy-solute complexes in Fe-MnNi and dilute Fe-X alloys: A kinetic Monte Carlo study

    NASA Astrophysics Data System (ADS)

    Messina, Luca; Malerba, Lorenzo; Olsson, Pär

    2015-06-01

    Manganese and nickel solute atoms in irradiated ferritic steels play a major role in the nanostructural evolution of reactor pressure vessels (RPV), as they are responsible for the formation of embrittling nanofeatures even in the absence of copper. The stability and mobility of small vacancy-solute clusters is here studied with an atomistic kinetic Monte Carlo approach based on ab initio calculations, in order to investigate the influence of Mn and Ni on the early life of small radiation-induced vacancy clusters, and to provide the necessary parameters for advanced object kinetic Monte Carlo simulations of the RPV long-term nanostructural evolution. Migration barriers are obtained by direct ab initio calculations or through a binding energy model based on ab initio data. Our results show a clear immobilizing and stabilizing effect on vacancy clusters as the solute content is increased, whereas the only evident difference between the two solute species is a somewhat longer elongation of the cluster mean free path in the presence of a few Mn atoms.

  3. Simple and accurate measurement of carbamazepine in surface water by use of porous membrane-protected micro-solid-phase extraction coupled with isotope dilution mass spectrometry.

    PubMed

    Teo, Hui Ling; Wong, Lingkai; Liu, Qinde; Teo, Tang Lin; Lee, Tong Kooi; Lee, Hian Kee

    2016-03-17

    To achieve fast and accurate analysis of carbamazepine in surface water, we developed a novel porous membrane-protected micro-solid-phase extraction (μ-SPE) method, followed by liquid chromatography-isotope dilution tandem mass spectrometry (LC-IDMS/MS) analysis. The μ-SPE device (∼0.8 × 1 cm) was fabricated by heat-sealing edges of a polypropylene membrane sheet to devise a bag enclosing the sorbent. The analytes (both carbamazepine and isotope-labelled carbamazepine) were first extracted by μ-SPE device in the sample (10 mL) via agitation, then desorbed in an organic solvent (1 mL) via ultrasonication. Several parameters such as organic solvent for pre-conditioning of μ-SPE device, amount of sorbent, adsorption time, and desorption solvent and time were investigated to optimize the μ-SPE efficiency. The optimized method has limits of detection and quantitation estimated to be 0.5 ng L(-1) and 1.6 ng L(-1), respectively. Surface water samples spiked with different amounts of carbamazepine (close to 20, 500, and 1600 ng L(-1), respectively) were analysed for the validation of method precision and accuracy. Good precision was obtained as demonstrated by relative standard deviations of 0.7% for the samples with concentrations of 500 and 1600 ng kg(-1), and 5.8% for the sample with concentration of 20 ng kg(-1). Good accuracy was also demonstrated by the relative recoveries in the range of 96.7%-103.5% for all samples with uncertainties of 1.1%-5.4%. Owing to the same chemical properties of carbamazepine and isotope-labelled carbamazepine, the isotope ratio in the μ-SPE procedure was accurately controlled. The use of μ-SPE coupled with IDMS analysis significantly facilitated the fast and accurate measurement of carbamazepine in surface water.

  4. 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.

  5. Impact of Water-Dilution on the Solvation Properties of the Ionic Liquid 1-Methyltriethoxy-3-ethylimidazolium Acetate for Model Biomass Molecules.

    PubMed

    Schutt, Timothy C; Hegde, Govind A; Bharadwaj, Vivek S; Johns, Adam J; Maupin, C Mark

    2017-02-02

    Many studies have suggested that the processing of lignocellulosic biomass could provide a renewable feedstock to supplant much of the current demand on petroleum sources. Currently, alkyl imidazolium-based ionic liquids (ILs) have shown considerable promise in the pretreatment, solvation, and hydrolysis of lignocellulosic materials although their high cost and unfavorable viscosity has limited their widespread use. Functionalizing these ILs with an oligo(ethoxy) tail has previously been shown through experiment to decrease the IL's viscosity resulting in enhanced mass transport characteristics, in addition to other favorable traits including decreased inhibition of some enzymes. Additionally, the use of cosolvents to mitigate the cost and unfavorable traits of ILs is an area of growing interest with particular attention on water as the presence of water in biomass processes is inevitable. Through the use of biased and unbiased molecular dynamics (MD) simulations, this study provides a molecular-level perspective of the various solvent-solvent and solvent-solute interactions in binary mixtures of water and 1-methyltriethoxy-3-ethylimidazolium acetate ([Me-(OEt)3-Et-IM(+)] [OAc(-)]) in the presence of model cellulose compounds (i.e., glucose and cellobiose). It is observed that at ∼75% w/w IL and water a transition in the nanostructure of the solvent occurs between water-like and IL-like solvation characteristics. It is shown that H-bonding interactions between the anion and water are a major driving force that significantly impacts the solvent properties of the IL as well as conformational preferences of the cellulosic model compound. In addition, it is found that the oligo(ethoxy) cation tail is responsible for the reduction in the propensity for tail aggregation as compared to alkyl tails of similar length, which, combined with increased ionic shielding, results in increased diffusion and enhanced water-like solvation characteristics.

  6. Effects of unstable flow on solute transport in the marsh soil and exchange with coastal water

    NASA Astrophysics Data System (ADS)

    Shen, Chengji; Zhang, Chenming; Jin, Guangqiu; Kong, Jun; Li, Ling

    2016-12-01

    Recent studies of marsh hydraulics have focused on tide-induced pore water circulation as the main drive for solute transport in the marsh soil and exchange with coastal water. Our study revealed another important mechanism provided by unstable fingering flow, which largely modified solute transport paths. In the marsh interior, downward penetration of salt fingers forced ambient pore water and solute plumes to move upward and exit the marsh soil through marsh platform at relatively high concentrations, up to 2 orders of magnitude higher than exit solute concentrations at the tidal creek bed. The mixing of solute with ambient pore water in the marsh interior was intensified greatly by fingering flow. A critical distance to the creek was determined based on a field-scale model simulation to distinguish tidal circulation-dominated and fingering flow-dominated solute transport zones. The new transport mechanism has implications for understanding the fate of solutes in particularly salt marshes of low creek densities.

  7. The measurement of solute diffusion coefficients in dilute liquid alloys: the influence of unit gravity and g-jitter on buoyancy convection.

    PubMed

    Smith, R W; Yang, B J; Huang, W D

    2004-11-01

    Liquid diffusion experiments conducted on the MIR space station using the Canadian Space Agency QUELD II processing facility and the microgravity isolation mount (MIM) showed that g-jitter significantly increased the measured solute diffusion coefficients. In some experiments, milli-g forced vibration was superimposed on the sample when isolated from the ambient g-jitter; this resulted in markedly increased solute transport. To further explore the effects arising in these long capillary diffusion couples from the absence of unit-gravity and the presence of the forced g-jitter, the effects of a 1 milli-g forcing vibration on the mass transport in a 1.5 mm diameter long capillary diffusion couple have been simulated. In addition, to increase understanding of the role of unit gravity in determining the extent to which gravity can influence measured diffusion coefficient values, comparative experiments involving gold, silver, and antimony diffusing in liquid lead have been carried out using a similar QUELD II facility to that employed in the QUELD II/MIM/MIR campaign but under terrestrial conditions. It was found that buoyancy-driven convection may still persist in the liquid even when conditions are arranged for a continuously decreasing density gradient up the axis of a vertical long capillary diffusion couple due to the presence of small radial temperature gradients.

  8. Thermodynamic properties of nonpolar solutes in water and the structure of hydrophobic hydration shells

    SciTech Connect

    Grunwald, E.

    1986-09-17

    Experimental partial molar entropies and heat capacities in water for noble gases, nonpolar diatomic gases, and hydrocarbons were analyzed thermodynamically by delphic dissection to evaluate the contributions from solute-induced perturbations of the water network. These contributions, which are typically large, were then interpreted in terms of the familiar two-state model of liquid water. Changes in the fractions of the two states and of their relative enthalpies, per mole of solute, were thus evaluated. The numbers of water molecules that are nearest neighbors to the solute, and the manner in which the nearest neighbors are tied to the bulk water network, could be elucidated.

  9. Water-enhanced solvation of organic solutes in ketone and ester solvents

    SciTech Connect

    Lee, J.H.; Brunt, V. van; King, C.J. . Dept. of Chemical Engineering Lawrence Berkeley Lab., CA )

    1994-05-01

    Previous research has shown that the solubilities of dicarboxylic acids in certain electron-donor solvents are substantially increased in the presence of water. Information on solubilities, liquid-liquid equilibria and maximum-boiling ternary azeotropes was screened so as to identify other systems where codissolved water appears to enhance solvation of organic solutes in solvents. Several carboxylic acids, an alcohol, diols, and phenols were selected for examination as solutes in ketone and ester solvents. Effects of water upon solute solubilities and volatilities were measured. Results showed that water-enhanced solvation is greatest for carboxylic acids. Solute activity coefficients decreased by factors of 2--3, 6--8, and 7--10 due to the presence of water for mono-, di and tricarboxylic acids, respectively. Activity coefficients decreased by a factor of about 1.5 for ethanol and 1,2-propanediol as solutes. Water-enhanced solvation of phenols is small, when existent.

  10. Mathematical modeling of solute segregation and redistribution during freezing in peat and overlying water

    SciTech Connect

    Li, S.M.

    1985-01-01

    Freezing of the water in a peatland causes the redistribution of existing solutes in both the shallow water and the peat zone. Such solute redistribution phenomena are of interest for establishing the geochronology of deposits and determining the nature of pollutant burial. Understanding these phenomena is important for the consideration of peatlands as multi-use resources. This work presents the theoretical analyses and mathematical models to describe the solute redistribution processes during freezing in overlying water and interstitial water in the porous peat. The analyses include the segregation of the solute at the ice-water interface in both the overlying water and the peat zone, solute transport in overlying water, as well as adsorbable solute and non-adsorbable solute transport in the interstitial water of the peat zone. An algorithm has been developed to solve these nonlinear moving interface problems. A parameter estimation technique has been used to determine parameters in the model that are difficult to obtain directly from the experimental data. Computer simulation using this model provides good predictions for solute concentration profiles in the frozen water and the peat zones, as compared to independent experimental data. The basic theoretical analysis and the mathematical model have been utilized to describe the salt ice formation process and macrosegregation during freezing of binary alloys.

  11. Detection of trace elements in DI water and comparison of several water solutions by using EF-FLRD chemical sensors

    NASA Astrophysics Data System (ADS)

    Kaya, M.; Wang, C.

    2017-02-01

    Detection of trace elements in DI water and comparison of several types of water respons such as DI water, tap water, and ocean water were studied by using EF-FLRD chemical sensors. Solutions of Mg, Fe, P, and Cd elements with a concentration of 1000 µg/ml (1 mg/ml) which corresponds to 1000 ppm by weight were tested. DI water, tap water, and real ocean water were utilized as medium to observe refractive index difference of solutions. The EF sensing technique which is based on the EF scattering effect was employed for the detection of trace chemicals and recording of solution responses. Due to the refractive index differences between solutions, optical loss of the sensor was different when the sensor head was immersed into solutions of approximately 10 ml each. The differences of the refractive indices are presented by recording ringdown times when the sensor head was immersed into the solutions. Fast response (˜1s), high sensitive, and reproducible EF-FLRD chemical sensors were fabricated and tested in laboratory conditions. High sensitivity of the sensors due to being capability of detecting smaller differences between measurands without any additional components or treatment makes the EF-FLRD sensors more attractive. Enhanced sensitivity of the EF-FLRD chemical sensors as a result of the multi-pass nature of the FLRD technique has potential application in detecting of trace elements in monitoring of water quality.

  12. 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.

  13. Study on the Unfrozen Water Quantity of Maximally Freeze-Concentrated Solutions for Multicomponent Lyoprotectants.

    PubMed

    Xu, Mengjie; Chen, Guangming; Zhang, Cunhai; Zhang, Shaozhi

    2017-01-01

    The concentration of maximally freeze-concentrated solutions [Formula: see text] and the corresponding glass transition temperature [Formula: see text] and ante-melting temperature [Formula: see text] of lyoprotectant solutions, are critical parameters for developing lyophilization process. Usually, the lyoprotectant solutions are multicomponent solutions composed of electrolytes, sugars, proteins, polymers, and other chemicals. In this article, the Wg(') values of several multicomponent solutions including trehalose/NaCl, bovine serum albumin/NaCl, and hydroxyethyl starch/NaCl with water were determined by differential scanning calorimetry. A linear relationship between the unfrozen water fraction Wun and the initial solute concentrations Wi was found: Wun = ∑(ai·Wi), which suggested that in the multicomponent solutions each solute could hydrate a certain amount of water ai (g water/g solute) that could not be frozen. The hypothesis was compared with more literature data. For the same solute in different solutions, variation in the fitted coefficient ai is noticed and discussed. If a "universal" value ai for each solute is adopted, both [Formula: see text] and [Formula: see text] for a multicomponent solution could be predicted if Couchman-Karasz equation is adopted for calculating glass transition temperature at the same time. The prediction discrepancies for [Formula: see text] with experimental data were less than 2°C. The finding is discussed about its molecular basis and applicability.

  14. 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

  15. 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%.

  16. 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.

  17. Exact solutions of one-dimensional nonlinear shallow water equations over even and sloping bottoms

    NASA Astrophysics Data System (ADS)

    Chirkunov, Yu. A.; Dobrokhotov, S. Yu.; Medvedev, S. B.; Minenkov, D. S.

    2014-03-01

    We establish an equivalence of two systems of equations of one-dimensional shallow water models describing the propagation of surface waves over even and sloping bottoms. For each of these systems, we obtain formulas for the general form of their nondegenerate solutions, which are expressible in terms of solutions of the Darboux equation. The invariant solutions of the Darboux equation that we find are simplest representatives of its essentially different exact solutions (those not related by invertible point transformations). They depend on 21 arbitrary real constants; after "proliferation" formulas derived by methods of group theory analysis are applied, they generate a 27-parameter family of essentially different exact solutions. Subsequently using the derived infinitesimal "proliferation" formulas for the solutions in this family generates a denumerable set of exact solutions, whose linear span constitutes an infinite-dimensional vector space of solutions of the Darboux equation. This vector space of solutions of the Darboux equation and the general formulas for nondegenerate solutions of systems of shallow water equations with even and sloping bottoms give an infinite set of their solutions. The "proliferation" formulas for these systems determine their additional nondegenerate solutions. We also find all degenerate solutions of these systems and thus construct a database of an infinite set of exact solutions of systems of equations of the one-dimensional nonlinear shallow water model with even and sloping bottoms.

  18. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 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...

  19. 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 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...

  20. 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...

  1. 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...

  2. 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.

  3. On the emergence of diel solute signals in flowing waters

    NASA Astrophysics Data System (ADS)

    Hensley, Robert T.; Cohen, Matthew J.

    2016-02-01

    Biota imprint their stoichiometry on relative rates of elemental cycling in the environment. Despite this coupling, producer-driven diel solute variation in rivers and streams is more apparent for some solutes (e.g., dissolved oxygen—DO) than others (e.g., nitrate—NO3-). We hypothesized that these differences arise from atmospheric equilibration, with signals emerging and evolving differently for gaseous and nongaseous solutes. Measurements of DO and NO3 in a spring-fed river, where constant inputs isolate in-stream processing, support this hypothesis, as do results from reactive transport modeling of river solute dynamics. Atmospheric equilibration dramatically shortens the benthic footprint over which signals integrate, facilitating emergence of diel DO signals in response to in-stream metabolism. In contrast, upstream influences persist much further downstream for nongaseous solutes, confounding and potentially obscuring the diel signals from in-stream assimilatory processing. Isolating diel NO3 signals from in-stream processing requires a two-station approach wherein metabolic impacts on solute variation are measured by difference between upstream and downstream sensors. Notably, two-station inference improves markedly when hydraulic controls on signal propagation such as dispersion and storage are explicitly considered. We conclude that the absence of diel signals at a single station for nongaseous solutes such as NO3- cannot be interpreted as lack of autotroph demand or element coupling. As advances in sensors enable the acquisition of an increasingly rich array of solute signals, controlling for differences in the emergence and downstream evolution of gaseous versus nongaseous solutes will dramatically improve inferences regarding the timing and magnitude of coupled elemental processing.

  4. 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.

  5. 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.

  6. Molecular properties of aqueous solutions: a focus on the collective dynamics of hydration water.

    PubMed

    Comez, L; Paolantoni, M; Sassi, P; Corezzi, S; Morresi, A; Fioretto, D

    2016-07-07

    When a solute is dissolved in water, their mutual interactions determine the molecular properties of the solute on one hand, and the structure and dynamics of the surrounding water particles (the so-called hydration water) on the other. The very existence of soft matter and its peculiar properties are largely due to the wide variety of possible water-solute interactions. In this context, water is not an inert medium but rather an active component, and hydration water plays a crucial role in determining the structure, stability, dynamics, and function of matter. This review focuses on the collective dynamics of hydration water in terms of retardation with respect to the bulk, and of the number of molecules whose dynamics is perturbed. Since water environments are in a dynamic equilibrium, with molecules continuously exchanging from around the solute towards the bulk and vice versa, we examine the ability of different techniques to measure the water dynamics on the basis of the explored time scales and exchange rates. Special emphasis is given to the collective dynamics probed by extended depolarized light scattering and we discuss whether and to what extent the results obtained in aqueous solutions of small molecules can be extrapolated to the case of large biomacromolecules. In fact, recent experiments performed on solutions of increasing complexity clearly indicate that a reductionist approach is not adequate to describe their collective dynamics. We conclude this review by presenting current ideas that are being developed to describe the dynamics of water interacting with macromolecules.

  7. Microfluidic serial dilution circuit.

    PubMed

    Paegel, Brian M; Grover, William H; Skelley, Alison M; Mathies, Richard A; Joyce, Gerald F

    2006-11-01

    In vitro evolution of RNA molecules requires a method for executing many consecutive serial dilutions. To solve this problem, a microfluidic circuit has been fabricated in a three-layer glass-PDMS-glass device. The 400-nL serial dilution circuit contains five integrated membrane valves: three two-way valves arranged in a loop to drive cyclic mixing of the diluent and carryover, and two bus valves to control fluidic access to the circuit through input and output channels. By varying the valve placement in the circuit, carryover fractions from 0.04 to 0.2 were obtained. Each dilution process, which is composed of a diluent flush cycle followed by a mixing cycle, is carried out with no pipeting, and a sample volume of 400 nL is sufficient for conducting an arbitrary number of serial dilutions. Mixing is precisely controlled by changing the cyclic pumping rate, with a minimum mixing time of 22 s. This microfluidic circuit is generally applicable for integrating automated serial dilution and sample preparation in almost any microfluidic architecture.

  8. 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.

  9. 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

  10. Molecular dynamics simulations of water, solution, and clay mineral-water systems (Invited)

    NASA Astrophysics Data System (ADS)

    Kawamura, K.

    2009-12-01

    Clays and clay minerals together with zeolites are major mineral components in the earth's surface environment. These minerals interact with the atmosphere, natural water, inorganic and organic components in soils, etc. Physicochemical processes in the surface region are generally complex and difficult to understand because of the complicated "molecular" structures and the ambient conditions under wet circumstances. We have investigated the structure and physical/dynamical properties of the mineral-gas/liquid systems by means of molecular simulation methods; molecular dynamics and Metropolis Monte Carlo methods. Swelling of smectite and adsorption of inorganic molecules in clay minerals and zeolites, etc. were simulated and analyzed on the basis of the atomic and molecular processes. We have developed atomic and molecular interaction models of inorganic systems. The models compose of electrostatic, short range repulsive, van der Waals and covalent (radial and angular) terms with respect to all the elements appeared in the mineral-water systems. All of our molecular dynamics simulations (MD) were performed with full degree of freedom of atom motions. Using the model for H2O molecule, the structure and physical properties such as density, diffusion coefficients, etc. of ice polymorphs and water are well reproduced. Alkaliharide aqueous solutions and gas hydrates and their (hydrophobic) solutions are also reasonably simulated. Clay mineral-water interactions are particularly important to understand the mechanical and chemical processes in the environments, in order to develop nano-composite materials, and to use clays in engineering applications. Absorption and swelling are the most remarkable properties of clay minerals, specially smectite. We have investigate these properties by means of molecular simulation methods using various clay minerals-water/solution systems. The swelling curves, the relation between humidity and the basal spacings, were reproduced

  11. Fluorescence correlation spectroscopy at the oil-water interface: hard disk diffusion behavior in dilute beta-lactoglobulin layers precedes monolayer formation.

    PubMed

    Donsmark, Jesper; Rischel, Christian

    2007-06-05

    We have performed a thorough characterization of fluorescence correlations spectroscopy (FCS) applied to oil-water interfaces of viscous oil droplets in aqueous solution, including numerical wave-optical calculations of the detection geometry and regularized multicomponent analysis of sample data. It is shown how significant errors in the estimation of the surface concentration can be avoided when FCS is applied to an interface region. We present data on the adsorption dynamics of beta-lactoglobulin (BLG), a well-studied model system. It is found that electrostatic repulsion slows the adsorption process and reduces the initial saturation density far below the monolayer concentration. During the first stages of adsorption, the diffusion coefficients of adsorbed protein closely follow the 2D hard disk model of Lahtinen et al.1 in response to increased surface concentration, which suggests that protein-protein interactions are limited to long-range Coulombic interactions at this stage.

  12. Isolation of nonvolatile, organic solutes from natural waters by zeotrophic distillation of water from N,N-dimethylformamide

    SciTech Connect

    Leenheer, J.A.; Brown, P.A.; Stiles, E.A.

    1987-05-01

    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-dimethylformamide-formic 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.

  13. 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.

  14. 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.

  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. 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.

  17. A serial dilution microfluidic device for cytotoxicity assays.

    PubMed

    O'Neill, Adrian T; Monteiro-Riviere, Nancy; Walker, Glenn M

    2006-01-01

    A novel microfluidic device is presented which creates a linear serial dilution of two input fluid streams. This platform facilitates higher productivity as a component of a high throughput cytotoxicity testing strategy. A modeling solution is presented to create custom linear dilution schemes. The featured device creates a serial dilution of two solutions in the range of 1:9 through 9:1 across nine discrete dilutions. It has been validated to create a highly linear progression of dilutions with an R2 value of 0.9993. The device functions equivalently over a wide range of flow rates. The standard deviation of dilution values averages 0.76% over six flow rates spanning 0.5 to 16 microl min(-1).

  18. 43 CFR 3594.5 - Minerals soluble in water; brines; minerals taken in solution.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... water; brines; minerals taken in solution. (a) In mining or prospecting deposits of sodium, potassium or other minerals soluble in water, all wells, shafts, prospecting holes and other openings shall be... 43 Public Lands: Interior 2 2014-10-01 2014-10-01 false Minerals soluble in water;...

  19. 43 CFR 3594.5 - Minerals soluble in water; brines; minerals taken in solution.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... water; brines; minerals taken in solution. (a) In mining or prospecting deposits of sodium, potassium or other minerals soluble in water, all wells, shafts, prospecting holes and other openings shall be... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Minerals soluble in water;...

  20. 43 CFR 3594.5 - Minerals soluble in water; brines; minerals taken in solution.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... water; brines; minerals taken in solution. (a) In mining or prospecting deposits of sodium, potassium or other minerals soluble in water, all wells, shafts, prospecting holes and other openings shall be... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Minerals soluble in water;...

  1. Origin of hydrophobicity and enhanced water hydrogen bond strength near purely hydrophobic solutes

    PubMed Central

    Grdadolnik, Joze; Merzel, Franci; Avbelj, Franc

    2017-01-01

    Hydrophobicity plays an important role in numerous physicochemical processes from the process of dissolution in water to protein folding, but its origin at the fundamental level is still unclear. The classical view of hydrophobic hydration is that, in the presence of a hydrophobic solute, water forms transient microscopic “icebergs” arising from strengthened water hydrogen bonding, but there is no experimental evidence for enhanced hydrogen bonding and/or icebergs in such solutions. Here, we have used the redshifts and line shapes of the isotopically decoupled IR oxygen–deuterium (O-D) stretching mode of HDO water near small purely hydrophobic solutes (methane, ethane, krypton, and xenon) to study hydrophobicity at the most fundamental level. We present unequivocal and model-free experimental proof for the presence of strengthened water hydrogen bonds near four hydrophobic solutes, matching those in ice and clathrates. The water molecules involved in the enhanced hydrogen bonds display extensive structural ordering resembling that in clathrates. The number of ice-like hydrogen bonds is 10–15 per methane molecule. Ab initio molecular dynamics simulations have confirmed that water molecules in the vicinity of methane form stronger, more numerous, and more tetrahedrally oriented hydrogen bonds than those in bulk water and that their mobility is restricted. We show the absence of intercalating water molecules that cause the electrostatic screening (shielding) of hydrogen bonds in bulk water as the critical element for the enhanced hydrogen bonding around a hydrophobic solute. Our results confirm the classical view of hydrophobic hydration. PMID:28028244

  2. 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.

  3. Microwave heating of water, ice, and saline solution: molecular dynamics study.

    PubMed

    Tanaka, Motohiko; Sato, Motoyasu

    2007-01-21

    In order to study the heating process of water by the microwaves of 2.5-20 GHz frequencies, the authors have performed molecular dynamics simulations by adopting a nonpolarizable water model that has fixed point charges on a rigid-body geometry. All runs are started from the equilibrated states derived from the I(c) ice with given density and temperature. In the presence of microwaves, the molecules of liquid water exhibit rotational motion whose average phase is delayed from the microwave electric field. Microwave energy is transferred to the kinetic and intermolecular energies of water, where one-third of the absorbed microwave energy is stored as the latter energy. The water in ice phase is scarcely heated by microwaves because of the tight hydrogen-bonded network of water molecules. Dilute salt water is significantly more heated than pure water because of the field-induced motion of salt ions, especially that of large-size ions, by the microwave electric field and energy transfer to water molecules by collisions.

  4. 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.

  5. 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.

  6. 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.

  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. 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.

  9. 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.

  10. Dilution Zone Mixing

    NASA Technical Reports Server (NTRS)

    Holdeman, J. D.

    1983-01-01

    Studies to characterize dilution zone mixing; experiments on the effects of free-stream turbulence on a jet in crossflow; and the development of an interactive computer code for the analysis of the mixing of jets with a confined crossflow are reviewed.

  11. 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.

  12. Acute barium intoxication following ingestion of soap water solution.

    PubMed

    Joshi, Nandita; Sharma, Chhavi Sarabpreert; Sai; Sharma, Jai Prakash

    2012-10-01

    We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels.

  13. Acute barium intoxication following ingestion of soap water solution

    PubMed Central

    Joshi, Nandita; Sharma, Chhavi Sarabpreert; Sai; Sharma, Jai Prakash

    2012-01-01

    We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels. PMID:23559738

  14. 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 controlli