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Sample records for liquid water polymorphism

  1. Are There Two Forms of Liquid Water?

    NASA Astrophysics Data System (ADS)

    Stanley, H. E.

    We will introduce some of the 73 documented anomalies of the most complex of liquids, water--focusing on recent progress in understanding these anomalies by combining information provided by recent experiments and simulations on water in bulk, nanoconfined and biological environments designed to test the hypothesis that liquid water has behavior consistent with the novel phenomenon of ``liquid polymorphism'' in that water can exist in two distinct phases [1]. We will also discuss very recent work on nanoconfined water anomalies as well as the apparently related, and highly unusual, behavior of water in biological environments. Finally, we will discuss how the general concept of liquid polymorphism is proving useful in understanding anomalies in other liquids, such as silicon, silica, and carbon, as well as metallic glasses, which have in common that they are characterized by two characteristic length scales in their interactions.This work has been supported by the NSF Chemistry Division grant CHE-1213217 and was performed in collaboration with, among others, C. A. Angell, S. V. Buldyrev, S.-H. Chen, D. Corradini, P. G. Debenedetti, G. Franzese, P. Kumar, E. Lascaris, F. Mallamace, O. Mishima, P. H. Poole, S. Sastry, F. Sciortino, and L. Xu. H. E. Stanley, Editor, Liquid Polymorphism, Vol. 152 in Advances in Chemical Physics, S. A. Rice, Series Editor (Wiley, New York, 2013).

  2. Liquid polymorphism, order-disorder transitions and anomalous behavior: A Monte Carlo study of the Bell-Lavis model for water

    NASA Astrophysics Data System (ADS)

    Fiore, Carlos E.; Szortyka, Marcia M.; Barbosa, Marcia C.; Henriques, Vera B.

    2009-10-01

    The Bell-Lavis model for liquid water is investigated through numerical simulations. The lattice-gas model on a triangular lattice presents orientational states and is known to present a highly bonded low density phase and a loosely bonded high density phase. We show that the model liquid-liquid transition is continuous, in contradiction with mean-field results on the Husimi cactus and from the cluster variational method. We define an order parameter which allows interpretation of the transition as an order-disorder transition of the bond network. Our results indicate that the order-disorder transition is in the Ising universality class. Previous proposal of an Ehrenfest second order transition is discarded. A detailed investigation of anomalous properties has also been undertaken. The line of density maxima in the HDL phase is stabilized by fluctuations, absent in the mean-field solution.

  3. Water: The Strangest Liquid

    SciTech Connect

    Nilsson, Anders

    2009-02-24

    Water, H2O, is familiar to everyone - it shapes our bodies and our planet. But despite its abundance, water has remained a mystery, exhibiting many strange properties that are still not understood. Why does the liquid have an unusually large capacity to store heat? And why is it denser than ice? Now, using the intense X-ray beams from particle accelerators, investigations into water are leading to fundamental discoveries about the structure and arrangement of water molecules. This lecture will elucidate the many mysteries of water and discuss current studies that are revolutionizing the way we see and understand one of the most fundamental substances of life.

  4. The Structure and Dynamics of Monatomic Liquid Polymorphs; Case Studies in Cerium and Germanium

    NASA Astrophysics Data System (ADS)

    Cadien, Adam

    The study of liquid polymorphism is at the frontier of fundamental thermodynamics and materials science. Liquid polymorphism occurs when a single material has multiple structurally unique liquid phases. Water was the first substance suggested to exhibit multiple liquid phases, a number of monatomic semiconductors and metals have been found to exhibit similar characteristics since then. A better understanding of the liquid-liquid phase transition is needed to tackle problems in glass sciences, it is also relevant to geophysical studies of the Earth's core and mantle and has applications in nanotechnology. Computational methods are critical to developing a better understanding of liquids. Through simulation thermodynamic obstacles that hamper experiments can be artificially bypassed, metastable regions outside the equilibrium phase diagram can be accessed and all of the properties of the system are directly recorded. Computationally it is much simpler to iterate over a range of environmental variables such as temperature, pressure and composition, and measure a system's response. In this thesis ab-initio and semi-empirical approximations are used to accurately describe the complex many body interactions that take place in liquids. Two independent case studies of liquid polymorphism are presented here. The first is a stable liquid-liquid phase transition was found to occur in Cerium which was initially discovered through X-Ray diffraction experiments and later confirmed through simulation. This phase transition is predicted to end at a critical point. The second is a comprehensive study of the structure and dynamics of Germanium's many metastable amorphous and liquid phases. This is currently the largest ab-initio based study of the dynamics of Germanium's metastable liquid phases. Methods ranging from the mean square displacement to the van Hove function and intermediate scattering function are introduced and analyzed. The micro-structural characteristics are

  5. Supercooled liquid water Estimation Tool

    Energy Science and Technology Software Center (ESTSC)

    2012-05-04

    The Cloud Supercooled liquid water Estimation Tool (SEET) is a user driven Graphical User Interface (GUI) that estimates cloud supercooled liquid water (SLW) content in terms of vertical column and total mass from Moderate resolution Imaging Supercooled liquid water Estimation Tool Spectroradiometer (MODIS) spatially derived cloud products and realistic vertical cloud parameterizations that are user defined. It also contains functions for post-processing of the resulting data in tabular and graphical form.

  6. Static heterogeneities in liquid water

    NASA Astrophysics Data System (ADS)

    Stanley, H. Eugene; Buldyrev, Sergey V.; Giovambattista, Nicolas

    2004-10-01

    The thermodynamic behavior of water seems to be closely related to static heterogeneities. These static heterogeneities are related to the local structure of water molecules, and when properly characterized, may offer an economical explanation of thermodynamic data. The key feature of liquid water is not so much that the existence of hydrogen bonds, first pointed out by Linus Pauling, but rather the local geometry of the liquid molecules is not spherical or oblong but tetrahedral. In the consideration of static heterogeneities, this local geometry is critical. Recent experiments suggested more than one phase of amorphous solid water, while simulations suggest that one of these phases is metastable with respect to another, so that in fact there are only two stable phases.

  7. Polymorphism in glassy silicon: Inherited from liquid-liquid phase transition in supercooled liquid

    NASA Astrophysics Data System (ADS)

    Zhang, Shiliang; Wang, Li-Min; Zhang, Xinyu; Qi, Li; Zhang, Suhong; Ma, Mingzhen; Liu, Riping

    2015-02-01

    Combining molecular dynamics (MD) simulation and Voronoi polyhedral analyses, we discussed the microstructure evolution in liquid and glassy silicon during cooling by focusing on the fraction of various clusters. Liquid-liquid phase transition (LLPT) is detected in supercooled liquid silicon However, freezing the high-density liquid (HDL) to the glassy state is not achieved as the quenching rate goes up to 1014 K/s. The polyamorphism in glassy silicon is found to be mainly associated with low-density liquid (LDL).

  8. Polymorphism in glassy silicon: Inherited from liquid-liquid phase transition in supercooled liquid

    PubMed Central

    Zhang, Shiliang; Wang, Li-Min; Zhang, Xinyu; Qi, Li; Zhang, Suhong; Ma, Mingzhen; Liu, Riping

    2015-01-01

    Combining molecular dynamics (MD) simulation and Voronoi polyhedral analyses, we discussed the microstructure evolution in liquid and glassy silicon during cooling by focusing on the fraction of various clusters. Liquid-liquid phase transition (LLPT) is detected in supercooled liquid silicon However, freezing the high-density liquid (HDL) to the glassy state is not achieved as the quenching rate goes up to 1014 K/s. The polyamorphism in glassy silicon is found to be mainly associated with low-density liquid (LDL). PMID:25716054

  9. Flow-assisted 2D polymorph selection: stabilizing metastable monolayers at the liquid-solid interface.

    PubMed

    Lee, Shern-Long; Yuan, Zhongyi; Chen, Long; Mali, Kunal S; Müllen, Klaus; De Feyter, Steven

    2014-05-28

    Controlling crystal polymorphism constitutes a formidable challenge in contemporary chemistry. Two-dimensional (2D) crystals often provide model systems to decipher the complications in 3D crystals. In this contribution, we explore a unique way of governing 2D polymorphism at the organic liquid-solid interface. We demonstrate that a directional solvent flow could be used to stabilize crystalline monolayers of a metastable polymorph. Furthermore, flow fields active within the applied flow generate millimeter-sized domains of either polymorph in a controlled and reproducible fashion. PMID:24867142

  10. Spontaneous liquid-liquid phase separation of water.

    PubMed

    Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

    2014-02-01

    We report a molecular dynamics simulation demonstrating a fast spontaneous liquid-liquid phase separation of water and a subsequent slow crystallization to ice. It is found that supercooled water separates rapidly into low- and high-density domains so as to reduce the surface energy in the rectangular simulation cell at certain thermodynamic states. The liquid-liquid phase separation, which is about two orders of magnitude faster than the crystallization, suggests a possibility to observe this phenomenon experimentally. PMID:25353404

  11. Inhomogeneities of stratocumulus liquid water

    NASA Technical Reports Server (NTRS)

    Cahalan, Robert F.; Snider, Jack B.

    1990-01-01

    There is a growing body of observational evidence on inhomogeneous cloud structure, most recently from the extensive measurements of the FIRE field program. Knowledge of cloud structure is important because it strongly influences the cloud radiative properties, one of the major factors in determining the global energy balance. Current atmospheric circulation models use plane-parallel radiation, so that the liquid water in each gridbox is assumed to be uniform, which gives an unrealistically large albedo. In reality cloud liquid water occupies only a subset of each gridbox, greatly reducing the mean albedo. If future climate models are to treat the hydrological cycle in a manner consistent with energy balance, a better treatment of cloud liquid is needed. FIRE concentrated upon two cloud types of special interest: cirrus and marine stratocumulus. Cirrus tend to be high and optically thin, thus reducing the effective radiative temperature without increasing the albedo significantly, leading to an enhanced greenhouse heating. In contrast, marine stratocumulus are low and optically thick, thus producing a large increase in reflected radiation with a small change in emitted radiation, giving a net cooling which could potentially mitigate the expected greenhouse warming. The FIRE measurements in California stratocumulus during June and July of 1987 show variations in cloud liquid water on all scales. Such variations are associated with inhomogeneous entrainment, in which entrained dry air, rather than mixing uniformly with cloudy air, remains intact in blobs of all sizes, which decay only slowly by invasion of cloudy air. Two important stratocumulus observations are described, followed by a simple fractal model which reproduces these properties, and finally, the model radiative properties are discussed.

  12. Liquid Water, the ``Most Complex'' Liquid: New Results in Bulk, Nanoconfined, and Biological Environments

    NASA Astrophysics Data System (ADS)

    Stanley, H. Eugene

    2010-03-01

    We will introduce some of the 63 anomalies of the most complex of liquids, water. We will demonstrate some recent progress in understanding these anomalies by combining information provided by recent experiments and simulations on water in bulk, nanoconfined, and biological environments. We will interpret evidence from recent experiments designed to test the hypothesis that liquid water may display ``polymorphism'' in that it can exist in two different phases---and discuss recent work on water's transport anomalies [1] as well as the unusual behavior of water in biological environments [2]. Finally, we will discuss how the general concept of liquid polymorphism [3] is proving useful in understanding anomalies in other liquids, such as silicon, silica, and carbon, as well as metallic glasses, which have in common that they are characterized by two characteristic length scales in their interactions. This work was supported by NSF Chemistry Division, and carried out in collaboration with a number of colleagues, chief among whom are C. A. Angell, M. C. Barbosa, M. C. Bellissent, L. Bosio, F. Bruni, S. V. Buldyrev, M. Canpolat, S. -H. Chen, P. G. Debenedetti, U. Essmann,G. Franzese, A. Geiger, N. Giovambattista, S. Han, P. Kumar, E. La Nave,G. Malescio, F. Mallamace, M. G. Mazza, O. Mishima, P. Netz, P. H. Poole, P. J. Rossky, R. Sadr,S. Sastry, A. Scala, F. Sciortino, A. Skibinsky, F. W. Starr, K. C. Stokely J. Teixeira, L. Xu, and Z. Yan.[4pt] [1] L. Xu, F. Mallamace, Z. Yan, F. W. Starr, S. V. Buldyrev, and H. E. Stanley, ``Appearance of a Fractional Stokes-Einstein Relation in Water and a Structural Interpretation of Its Onset,'' Nature Physics 5, 565--569 (2009). [0pt] [2] P. Kumar, Z. Yan, L. Xu, M. G. Mazza, S. V. Buldyrev, S. -H. Chen. S. Sastry, and H. E. Stanley, ``Glass Transition in Biomolecules and the Liquid-Liquid Critical Point of Water,'' Phys. Rev. Lett. 97, 177802 (2006). [0pt] [3] H. E. Stanley, ed. , Liquid Polymorphism [Advances in Chemical Physics

  13. Density Fluctuations in Liquid Water

    NASA Astrophysics Data System (ADS)

    English, Niall J.; Tse, John S.

    2011-01-01

    The density distributions and fluctuations in grids of varying size in liquid water at ambient pressure, both above the freezing point and in the supercooled state, are analyzed from the trajectories obtained from large-scale molecular dynamics simulations. It is found that the occurrence of low- and high-density regions (LDL and HDL) is transient and their respective residence times are dependent on the size of the simulated system. The spatial extent of density-density correlation is found to be within 7 Å or less. The temporal existence of LDL and HDL arises as a result of natural density fluctuations of an equilibrium system. The density of bulk water at ambient conditions is homogenous.

  14. Geomorphologic evidence for liquid water

    USGS Publications Warehouse

    Masson, P.; Carr, M.H.; Costard, F.; Greeley, R.; Hauber, E.; Jaumann, R.

    2001-01-01

    Besides Earth, Mars is the only planet with a record of resurfacing processes and environmental circumstances that indicate the past operation of a hydrologic cycle. However the present-day conditions on Mars are far apart of supporting liquid water on the surface. Although the large-scale morphology of the Martian channels and valleys show remarkable similarities with fluid-eroded features on Earth, there are major differences in their size, small-scale morphology, inner channel structure and source regions indicating that the erosion on Mars has its own characteristic genesis and evolution. The different landforms related to fluvial, glacial and periglacial activities, their relations with volcanism, and the chronology of water-related processes, are presented.

  15. Role of water in Protein Aggregation and Amyloid Polymorphism

    PubMed Central

    Thirumalai, D.; Reddy, Govardhan; Straub, John E.

    2011-01-01

    stage, the peptides align along a preferred axis to form ordered structures with anti-parallel β-strand arrangement. The rate limiting step in the ordered assembly is the rearrangement of the peptides within a confining volume. The mechanism of protofilament formation in a polar peptide fragment from the yeast prion in which the two sheets are packed against each other creating a dry interface illustrates that water dramatically slows down self-assembly. As the sheets approach each other two perfectly ordered one-dimensional water wires, which are stabilized by hydrogen bonds to the amide groups of the polar side chains, results in the formation of long-lived metastable structures. Release of the trapped water from the pore creates a helically-twisted protofilament with a dry interface. Similarly, the driving force for addition of a solvated monomer to a preformed fibril is the release of water whose entropy gain and favorable inter peptide hydrogen bond formation compensates for loss in entropy of the peptides. We suggest that the two-step mechanism, a model also used in protein crystallization, must hold good for higher order amyloid structure formation. In the first step a liquid droplet rich in proteins containing N* structures form. Conformational rearrangement of the peptides leading to an ordered state occurs within the droplet by incorporation of monomers or collision with other droplets and ultimately results in β-amyloid formation. Because there is an ensemble of distinct N* structures with varying water content there must be a number of distinct water-laden polymorphic structures. Evidence for this proposal is presented. Water plays multifarious roles, which in the case of predominantly hydrophobic sequences, accelerates fibril formation. In contrast, water-stabilized metastable intermediates dramatically slow down fibril growth rates in hydrophilic sequences. PMID:21761818

  16. Liquid Water on Early Mars

    NASA Technical Reports Server (NTRS)

    Davis, Wanda L.; McKay, Christopher P.

    1994-01-01

    We have used a simple climate model to determine the duration of liquid water habitats on early Mars following up on the previous work of McKay and Davis. We used the weathering model of Pollack et al. to compute the pressure and temperature evolution of the atmosphere. We included the variability of the solar luminosity. Recent results which have considered the influence of CO2 condensation suggest that Mars could not have been kept warm (above 0 C) with only a dense CO2 atmosphere. New stellar evolution theories have suggested a more massive early sun to explain the lithium depletion in the sun and predict a warmer climate for early Mars. We have therefore modified the model of McKay and Davis to include the effects of CO2 condensation and the effect of a more massive early sun. Here we present the results of these additional effects on the duration of liquid water habitats on early Mars. We find that the increased luminosity suggested for the early sun when mass loss is taken into account can provide a climate on early Mars that results in fluvial features existing over 500 million years.

  17. The Boson peak in confined water: An experimental investigation of the liquid-liquid phase transition hypothesis

    NASA Astrophysics Data System (ADS)

    Mallamace, Francesco; Corsaro, Carmelo; Mallamace, Domenico; Wang, Zhe; Chen, Sow-Hsin

    2015-10-01

    The Boson peak (BP) of deeply cooled confined water is studied by using inelastic neutron scattering (INS) in a large interval of the ( P, T) phase plane. By taking into account the different behavior of such a collective vibrational mode in both strong and fragile glasses as well as in glass-forming materials, we were able to determine the Widom line that characterizes supercooled bulk water within the frame of the liquid-liquid phase transition (LLPT) hypothesis. The peak frequency and width of the BP correlated with the water polymorphism of the LLPT scenario, allowing us to distinguish the "low-density liquid" (LDL) and "high-density liquid" (HDL) phases in deeply cooled bulk water.Moreover, the BP properties afford a further confirmation of theWidom line temperature T W as the ( P, T) locus in which the local structure of water transforms from a predominately LDL form to a predominately HDL form.

  18. Raman lidar observations of cloud liquid water.

    PubMed

    Rizi, Vincenzo; Iarlori, Marco; Rocci, Giuseppe; Visconti, Guido

    2004-12-10

    We report the design and the performances of a Raman lidar for long-term monitoring of tropospheric aerosol backscattering and extinction coefficients, water vapor mixing ratio, and cloud liquid water. We focus on the system's capabilities of detecting Raman backscattering from cloud liquid water. After describing the system components, along with the current limitations and options for improvement, we report examples of observations in the case of low-level cumulus clouds. The measurements of the cloud liquid water content, as well as the estimations of the cloud droplet effective radii and number densities, obtained by combining the extinction coefficient and cloud water content within the clouds, are critically discussed. PMID:15617280

  19. Water flow and fin shape polymorphism in coral reef fishes.

    PubMed

    Binning, Sandra A; Roche, Dominique G

    2015-03-01

    Water flow gradients have been linked to phenotypic differences and swimming performance across a variety of fish assemblages. However, the extent to which water motion shapes patterns of phenotypic divergence within species remains unknown. We tested the generality of the functional relationship between swimming morphology and water flow by exploring the extent of fin and body shape polymorphism in 12 widespread species from three families (Acanthuridae, Labridae, Pomacentridae) of pectoral-fin swimming (labriform) fishes living across localized wave exposure gradients. The pectoral fin shape of Labridae and Acanthuridae species was strongly related to wave exposure: individuals with more tapered, higher aspect ratio (AR) fins were found on windward reef crests, whereas individuals with rounder, lower AR fins were found on leeward, sheltered reefs. Three of seven Pomacentridae species showed similar trends, and pectoral fin shape was also strongly related to wave exposure in pomacentrids when fin aspect ratios of three species were compared across flow habitats at very small spatial scales (<100 m) along a reef profile (reef slope, crest, and back lagoon). Unlike fin shape, there were no intraspecific differences in fish body fineless ratio across habitats or depths. Contrary to our predictions, there was no pattern relating species' abundances to polymorphism across habitats (i.e., abundance was not higher at sites where morphology is better adapted to the environment). This suggests that there are behavioral and/or physiological mechanisms enabling some species to persist across flow habitats in the absence of morphological differences. We suggest that functional relationships between swimming morphology and water flow not only structure species assemblages, but are yet another important variable contributing to phenotypic differences within species. The close links between fin shape polymorphism and local water flow conditions appear to be important for

  20. Dipolar correlations in liquid water

    SciTech Connect

    Zhang, Cui; Galli, Giulia

    2014-08-28

    We present an analysis of the dipolar correlations in water as a function of temperature and density and in the presence of simple ionic solutes, carried out using molecular dynamics simulations and empirical potentials. We show that the dipole-dipole correlation function of the liquid exhibits sizable oscillations over nanodomains of about 1.5 nm radius, with several isosbestic points as a function of temperature; the size of the nanodomains is nearly independent on temperature and density, between 240 and 400 K and 0.9 and 1.3 g/cm{sup 3}, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (τ) of the system dipole moment varies by a factor of about 30 and 1.5, as a function of temperature and density, respectively. At 300 K, we observed a maximum in τ as a function of density, and a corresponding shallow maximum in the tetrahedral order parameter, in a range where the diffusion coefficient, the pressure and the dielectric constant increase monotonically.

  1. Comment on "Spontaneous liquid-liquid phase separation of water".

    PubMed

    Limmer, David T; Chandler, David

    2015-01-01

    Yagasaki et al. [Phys. Rev. E 89, 020301 (2014)] present results from a molecular dynamics trajectory illustrating coarsening of ice, which they interpret as evidence of transient coexistence between two distinct supercooled phases of liquid water. We point out that neither two distinct liquids nor criticality are demonstrated in this simulation study. Instead, the illustrated trajectory is consistent with coarsening behaviors analyzed and predicted in earlier work by others. PMID:25679744

  2. Photoresponsive liquid marbles and dry water.

    PubMed

    Tan, Tristan Tsai Yuan; Ahsan, Aniq; Reithofer, Michael R; Tay, Siok Wei; Tan, Sze Yu; Hor, Tzi Sum Andy; Chin, Jia Min; Chew, Benny Kia Jia; Wang, Xiaobai

    2014-04-01

    Stimuli-responsive liquid marbles for controlled release typically rely on organic moieties that require lengthy syntheses. We report herein a facile, one-step synthesis of hydrophobic and oleophobic TiO2 nanoparticles that display photoresponsive wettability. Water liquid marbles stabilized by these photoresponsive TiO2 particles were found to be stable when shielded from ultraviolet (UV) radiation; however, they quickly collapsed after being irradiated with 302 nm UV light. Oil- and organic-solvent-based liquid marbles could also be fabricated using oleophobic TiO2 nanoparticles and show similar UV-induced collapse. Finally, we demonstrated the formation of the micronized form of water liquid marbles, also known as dry water, by homogenization of the TiO2 nanoparticles with water. The TiO2 dry water displayed a similar photoresponse, whereby the micronized liquid marbles collapsed after irradiation and the dry water turned from a free-flowing powder to a paste. Hence, by exploiting the photoresponsive wettability of TiO2, we fabricated liquid marbles and dry water that display photoresponse and studied the conditions required for their collapse. PMID:24617527

  3. Application of ionic liquid to polymorphic transformation of anti-viral/HIV drug adefovir dipivoxil.

    PubMed

    An, Ji-Hun; Jin, Feng; Kim, Hak Sung; Ryu, Hyung Chul; Kim, Jae Sun; Kim, Hyuk Min; Kiyonga, Alice Nguvoko; Min, Dong Sun; Youn, Wonno; Kim, Ki Hyun; Jung, Kiwon

    2016-05-01

    Ionic liquids (ILs) are defined as salts with a melting point below 100 °C. ILs have received increasing attention as new alternative to organic solvents because of their unique physicochemical properties. Therefore, this study was conducted in the purpose to present the efficacy of ILs as new solvents capable to control the Polymorphic transformation phenomenon. Here, the polymorphic transformation phenomenon of adefovir dipivoxil, an efficient antiviral active pharmaceutical ingredient on human immunodeficiency virus, was investigated. The phase transformation phenomenon from the metastable polymorph, new form (NF) to the stable polymorph, Form-X in 1-allyl-3-ethylimidazolium tetrafluoroborate (AEImBF4) and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (BDMImBF4) ILs solutions was observed utilizing the solvent-mediated phase transformation method The thermodynamic factors, AEImBF4/BDMImBF4 solvent composition ratio of 3:7-6:4 and the temperature in range of 25-100 °C, as well as the dynamic factor, the rational speed in range of 300-1000 rpm were parameters studied in this experiment. The thermodynamic and dynamic equations involving nucleation and mass transfer were applied for the quantitative analysis. The result of the present study confirmed the use of ILs as substitute solvent for volatile organic solvents, and demonstrated the efficacy of ILs as potential solvent-media to control the polymorphic transformation. PMID:26908332

  4. Evidence for Liquid Water on Comets

    NASA Technical Reports Server (NTRS)

    Sheldon, Robert; Hoover, Richard

    2005-01-01

    We have reexamined the arguments for the existence of liquid water on comets, and believe that recent cometary flybys along with pre-Giotto data support its presence on short-period comets. Liquid water would affect cometary dynamics, leaving distinct signatures in precession, orbital dynamics, and potential splitting of comets. Liquid water geysers would affect cometary atmosphere, dust evolution, and non-gravitational forces that perturb the orbit. Liquid water would affect the composition of both the interior and exterior of the comet, producing geologic effects consistent with recent flyby photographs. And most importantly, liquid water suppork the growth of lifeforms, which would make a comet a biofriendly incubator for interplanetary transport. The major objection against liquid water is the necessity of a pressure vessel to prevent sublimation into space. We discuss how such a pressure vessel could naturally evolve as a pristine comet makes its first journey inside the orbit of Mars, and suggest that this type of vessel was observed by Giotto, Deep Space I, and Stardust.

  5. Polymorphic transitions in n-hydrocarbon-water and n-alcohol-water binary systems

    NASA Astrophysics Data System (ADS)

    Mirgorod, Yu. A.

    2014-08-01

    The mixing of hydrocarbons and alcohols in an excess of water is explained by polymorphic transitions similar to crystallization in an ensemble of water clusters. Enthalpies of transitions of 4.90 ± 0.07 and 2.2 ± 0.3 kJ/mol are obtained for solutions of hydrocarbons and alcohols in an excess of water, respectively. It is concluded that the mixing of water in an excess of hydrocarbons and alcohols is similar to evaporation (the breaking of H-bonds) with an enthalpy of 34 ± 1.4 kJ/mol. It is established that a polymorphic transition occurs between two binodals, and is accompanied by the emergence of microphases (concentration fluctuations) of alcohols in water. Binodals and spinodals in an excess of water and alcohol coincide for butyl and other higher alcohols.

  6. Spin-liquid polymorphism in a correlated electron system on the threshold of superconductivity

    PubMed Central

    Zaliznyak, Igor; Savici, Andrei T.; Lumsden, Mark; Tsvelik, Alexei; Hu, Rongwei; Petrovic, Cedomir

    2015-01-01

    We report neutron scattering measurements which reveal spin-liquid polymorphism in an “11” iron chalcogenide superconductor. It occurs when a poorly metallic magnetic state of FeTe is tuned toward superconductivity by substitution of a small amount of tellurium with isoelectronic sulfur. We observe a liquid-like magnetic response, which is described by the coexistence of two disordered magnetic phases with different local structures whose relative abundance depends on temperature. One is the ferromagnetic (FM) plaquette phase observed in undoped, nonsuperconducting FeTe, which preserves the C4 symmetry of the underlying square lattice and is favored at high temperatures, whereas the other is the antiferromagnetic plaquette phase with broken C4 symmetry, which emerges with doping and is predominant at low temperatures. These findings suggest the coexistence of and competition between two distinct liquid states, and a liquid–liquid phase transformation between these states, in the electronic spin system of FeTe1−x(S,Se)x. We have thus discovered the remarkable physics of competing spin-liquid polymorphs in a correlated electron system approaching superconductivity. Our results facilitate an understanding of large swaths of recent experimental data in unconventional superconductors. In particular, the phase with lower C2 local symmetry, whose emergence precedes superconductivity, naturally accounts for a propensity for forming electronic nematic states which have been observed experimentally, in cuprate and iron-based superconductors alike. PMID:26240327

  7. Properties of Water Confined in Ionic Liquids

    PubMed Central

    Saihara, Koji; Yoshimura, Yukihiro; Ohta, Soichi; Shimizu, Akio

    2015-01-01

    The varying states of water confined in the nano-domain structures of typical room temperature ionic liquids (ILs) were investigated by 1H NMR and by measurements of self-diffusion coefficients while systematically varying the IL cations and anions. The NMR peaks for water in BF4-based ILs were clearly split, indicating the presence of two discrete states of confined water (H2O and HOD). Proton and/or deuterium exchange rate among the water molecules was very slowly in the water-pocket. Notably, no significant changes were observed in the chemical shifts of the ILs. Self-diffusion coefficient results showed that water molecules exhibit a similar degree of mobility, although their diffusion rate is one order of magnitude faster than that of the IL cations and anions. These findings provide information on a completely new type of confinement, that of liquid water in soft matter. PMID:26024339

  8. Liquid chromatographic determination of water

    DOEpatents

    Fortier, N.E.; Fritz, J.S.

    1990-11-13

    A sensitive method for the determination of water in the presence of common interferences is presented. The detection system is based on the effect of water on the equilibrium which results from the reaction aryl aldehydes, such as cinnamaldehyde and methanol in the eluent to form cinnamaldehyde dimethylacetal, plus water. This equilibrium is shifted in a catalytic atmosphere of a hydrogen ion form past column reactor. The extent of the shift and the resulting change in absorbance are proportional to the amount of water present. 1 fig.

  9. Liquid chromatographic determination of water

    DOEpatents

    Fortier, Nancy E.; Fritz, James S.

    1990-11-13

    A sensitive method for the determination of water in the presence of common interferences is presented. The detection system is based on the effect of water on the equilibrium which results from the reaction aryl aldehydes, such as cinnamaldehyde and methanol in the eluent to form cinnamaldehyde dimethylacetal, plus water. This equilibrium is shifted in a catalytic atmosphere of a hydrogen ion form past column reactor. The extent of the shift and the resulting change in absorbance are proportional to the amount of water present.

  10. Liquid Water Oceans in Ice Giants

    NASA Technical Reports Server (NTRS)

    Wiktorowicz, Sloane J.; Ingersoll, Andrew P.

    2007-01-01

    Aptly named, ice giants such as Uranus and Neptune contain significant amounts of water. While this water cannot be present near the cloud tops, it must be abundant in the deep interior. We investigate the likelihood of a liquid water ocean existing in the hydrogen-rich region between the cloud tops and deep interior. Starting from an assumed temperature at a given upper tropospheric pressure (the photosphere), we follow a moist adiabat downward. The mixing ratio of water to hydrogen in the gas phase is small in the photosphere and increases with depth. The mixing ratio in the condensed phase is near unity in the photosphere and decreases with depth; this gives two possible outcomes. If at some pressure level the mixing ratio of water in the gas phase is equal to that in the deep interior, then that level is the cloud base. The gas below the cloud base has constant mixing ratio. Alternately, if the mixing ratio of water in the condensed phase reaches that in the deep interior, then the surface of a liquid ocean will occur. Below this ocean surface, the mixing ratio of water will be constant. A cloud base occurs when the photospheric temperature is high. For a family of ice giants with different photospheric temperatures, the cooler ice giants will have warmer cloud bases. For an ice giant with a cool enough photospheric temperature, the cloud base will exist at the critical temperature. For still cooler ice giants, ocean surfaces will result. A high mixing ratio of water in the deep interior favors a liquid ocean. We find that Neptune is both too warm (photospheric temperature too high) and too dry (mixing ratio of water in the deep interior too low) for liquid oceans to exist at present. To have a liquid ocean, Neptune s deep interior water to gas ratio would have to be higher than current models allow, and the density at 19 kbar would have to be approx. equal to 0.8 g/cu cm. Such a high density is inconsistent with gravitational data obtained during the Voyager

  11. Water Contaminant Mitigation in Ionic Liquid Propellant

    NASA Technical Reports Server (NTRS)

    Conroy, David; Ziemer, John

    2009-01-01

    Appropriate system and operational requirements are needed in order to ensure mission success without unnecessary cost. Purity requirements applied to thruster propellants may flow down to materials and operations as well as the propellant preparation itself. Colloid electrospray thrusters function by applying a large potential to a room temperature liquid propellant (such as an ionic liquid), inducing formation of a Taylor cone. Ions and droplets are ejected from the Taylor cone and accelerated through a strong electric field. Electrospray thrusters are highly efficient, precise, scaleable, and demonstrate low thrust noise. Ionic liquid propellants have excellent properties for use as electrospray propellants, but can be hampered by impurities, owing to their solvent capabilities. Of foremost concern is the water content, which can result from exposure to atmosphere. Even hydrophobic ionic liquids have been shown to absorb water from the air. In order to mitigate the risks of bubble formation in feed systems caused by water content of the ionic liquid propellant, physical properties of the ionic liquid EMI-Im are analyzed. The effects of surface tension, material wetting, physisorption, and geometric details of the flow manifold and electrospray emitters are explored. Results are compared to laboratory test data.

  12. Water: A Tale of Two Liquids.

    PubMed

    Gallo, Paola; Amann-Winkel, Katrin; Angell, Charles Austen; Anisimov, Mikhail Alexeevich; Caupin, Frédéric; Chakravarty, Charusita; Lascaris, Erik; Loerting, Thomas; Panagiotopoulos, Athanassios Zois; Russo, John; Sellberg, Jonas Alexander; Stanley, Harry Eugene; Tanaka, Hajime; Vega, Carlos; Xu, Limei; Pettersson, Lars Gunnar Moody

    2016-07-13

    Water is the most abundant liquid on earth and also the substance with the largest number of anomalies in its properties. It is a prerequisite for life and as such a most important subject of current research in chemical physics and physical chemistry. In spite of its simplicity as a liquid, it has an enormously rich phase diagram where different types of ices, amorphous phases, and anomalies disclose a path that points to unique thermodynamics of its supercooled liquid state that still hides many unraveled secrets. In this review we describe the behavior of water in the regime from ambient conditions to the deeply supercooled region. The review describes simulations and experiments on this anomalous liquid. Several scenarios have been proposed to explain the anomalous properties that become strongly enhanced in the supercooled region. Among those, the second critical-point scenario has been investigated extensively, and at present most experimental evidence point to this scenario. Starting from very low temperatures, a coexistence line between a high-density amorphous phase and a low-density amorphous phase would continue in a coexistence line between a high-density and a low-density liquid phase terminating in a liquid-liquid critical point, LLCP. On approaching this LLCP from the one-phase region, a crossover in thermodynamics and dynamics can be found. This is discussed based on a picture of a temperature-dependent balance between a high-density liquid and a low-density liquid favored by, respectively, entropy and enthalpy, leading to a consistent picture of the thermodynamics of bulk water. Ice nucleation is also discussed, since this is what severely impedes experimental investigation of the vicinity of the proposed LLCP. Experimental investigation of stretched water, i.e., water at negative pressure, gives access to a different regime of the complex water diagram. Different ways to inhibit crystallization through confinement and aqueous solutions are

  13. Water is a molecular liquid.

    PubMed

    Newman, Timothy

    2014-06-01

    Science and society are failing to grapple with the public health burden of cancer. In this short perspective piece, I contrast reductionism and complexity in cancer research, using water as a simple example, arguing for more 'ecological' approaches to cancer. This is a call to arms to physical scientists, ecologists and others to get involved, to link up with cancer clinicians and cancer biologists, and an appeal to funding agencies to link up across disciplines to make a difference. PMID:24732704

  14. Detection of prion gene promoter and intron1 indel polymorphisms in Anatolian water buffalo (Bubalus bubalis).

    PubMed

    Oztabak, K; Ozkan, E; Soysal, I; Paya, I; Un, C

    2009-12-01

    Bovine spongiform encephalopathy (BSE) is a fatal disease caused by miss folded prion protein. Studies in the cattle, comparing genetic data from BSE diseased and healthy animals have shown that indel polymorphisms in the promoter and intron 1 of PRNP gene were associated with disease susceptibility. Several studies were conducted to find out allele and genotypic frequencies of indel polymorphisms in promoter and intron 1 of the cattle PRNP gene. Unlike domestic cattle and bison, no indel polymorphisms of the PRNP promoter and intron 1 were examined in any population of the water buffalo (Bubalus bubalis). Aim of this study was to analyse frequencies of allele, genotype, and haplotype of the indel polymorphisms (23 bp indel in promoter and 12 bp indel in intron 1) in prion protein coding gene (PRNP) of water buffalo. Therefore a PCR based procedure, previously used in cattle to detect indel polymorphisms of PRNP promoter and intron 1 locus, was applied to 106 Anatolian water buffalo DNAs. Our results have revealed high frequency of in variants and in23/in12 haplotype for PRNP promoter and intron 1 indel polymorphisms in water buffalo. The results of the study have demonstrated that frequencies of allele, genotype, and haplotype of the indel polymorphisms in PRNP gene of the Anatolian water buffalo are significantly different those from cattle and bison PRNP indel polymorphisms. PMID:19912420

  15. Water is a molecular liquid

    NASA Astrophysics Data System (ADS)

    Newman, Timothy

    2014-06-01

    Science and society are failing to grapple with the public health burden of cancer. In this short perspective piece, I contrast reductionism and complexity in cancer research, using water as a simple example, arguing for more ‘ecological’ approaches to cancer. This is a call to arms to physical scientists, ecologists and others to get involved, to link up with cancer clinicians and cancer biologists, and an appeal to funding agencies to link up across disciplines to make a difference. This perspective is dedicated to the memory of Dr Kenneth Mossman (1946-2014).

  16. Liquid-liquid phase transitions and water-like anomalies in liquids

    NASA Astrophysics Data System (ADS)

    Lascaris, Erik

    In this thesis we employ computer simulations and statistical physics to understand the origin of liquid-liquid phase transitions and their relationship with anomalies typical of liquid water. Compared with other liquids, water has many anomalies. For example the density anomaly: when water is cooled below 4 °C the density decreases rather than increases. This and other anomalies have also been found to occur in a few other one-component liquids, sometimes in conjunction with the existence of a liquid-liquid phase transition (LLPT) between a low-density liquid (LDL) and a high-density liquid (HDL). Using simple models we explain how these anomalies arise from the presence of two competing length scales. As a specific example we investigate the cut ramp potential, where we show the importance of "competition" in this context, and how one length scale can sometimes be zero. When there is a clear energetic preference for either LDL or HDL for all pressures and temperatures, then there is insufficient competition between the two liquid structures and no anomalies occur. From the simple models it also follows that anomalies can occur without the presence of a LLPT and vice versa. It remains therefore unclear if water has a LLPT that ends in a liquid-liquid critical point (LLCP), a hypothesis that was first proposed based on simulations of the ST2 water model. We confirm the existence of a LLCP in this model using finite size scaling and the Challa-Landau-Binder parameter, and show that the LLPT is not a liquid-crystal transition, as has recently been suggested. Previous research has indicated the possible existence of a LLCP in liquid silica. We perform a detailed analysis of two different silica models (WAC and BKS) at temperatures much lower than was previously simulated. Within the accessible temperature range we find no LLCP in either model, although in the case of WAC potential it is closely approached. We compare our results with those obtained for other

  17. Spin-liquid polymorphism in an underdoped iron-chalcogenide superconductor

    NASA Astrophysics Data System (ADS)

    Zaliznyak, Igor; Savici, Andrei; Lumsden, Mark; Tsvelik, Alexei; Hu, Rongwei; Petrovic, Cedomir

    We report neutron scattering measurements which reveal spin-liquid polymorphism in an ``11'' iron chalcogenide superconductor. It occurs when a poorly metallic magnetic state of FeTe is driven toward superconductivity by substitution of a small amount of tellurium with isoelectronic sulfur. We observe a liquid-like magnetic response, which is described by the coexistence of two disordered magnetic phases with different local structures whose relative abundance depends on temperature. One is the ferromagnetic (FM) plaquette phase observed in undoped, nonsuperconducting FeTe, which preserves the C4 symmetry of the underlying square lattice and is favored at high temperatures, whereas the other is the antiferromagnetic plaquette phase with broken C4 symmetry, which emerges with doping and is predominant at low temperatures. These findings suggest the coexistence of and competition between two distinct liquid states, and a liquid-liquid phase transformation between these states, in the electronic spin system of FeTe1-x(S,Se)x. Our results shed light on many recent experimental data in unconventional superconductors. The phase with lower, C2 local symmetry, whose emergence precedes superconductivity, naturally accounts for a propensity to electronic nematic states. Work at BNL is supported by the Office of Basic Energy Sciences, US DOE, under Contract DE-SC00112704.

  18. Water in Olivine and its High-Pressure Polymorphs

    NASA Astrophysics Data System (ADS)

    Thomas, S. M.; Jacobsen, S. D.; Bina, C. R.; Reichart, P.; Moser, M.; Dollinger, G.; Hauri, E. H.

    2014-12-01

    Theory and high-pressure experiments imply a significant water storage capacity of nominally anhydrous minerals (NAMs), such as olivine, wadsleyite and ringwoodite, composing the Earth's upper mantle and transition zone to a depth of 660 km. The presence of water, dissolved as OH into such nominally anhydrous high-pressure silicates, notably influences phase relations, melting behavior, conductivity, elasticity, viscosity and rheology. The first direct evidence for hydration of the transition zone has recently been reported by Pearson et al. (2014) and Schmandt et al. (2014). Knowledge of absolute water contents in NAMs is essential for modeling the Earth's interior water cycle. To take advantage of IR spectroscopy as highly sensitive water quantification tool, mineral-specific absorption coefficients are required. Such calibration constants can be derived from hydrogen concentrations determined by independent techniques, such as secondary ion mass spectrometry (SIMS), Raman spectroscopy or proton-proton(pp)-scattering. Broad beam pp-scattering has been performed on double-polished mm-sized mineral platelets (Thomas et al. 2008), but until recently analysis was not feasible for smaller samples synthetized in high-pressure apparati. Here we present first results from pp-scattering microscopy studies on μm-sized single crystals of hydrous olivine, wadsleyite and ringwoodite, which were synthesized at various pressure-temperature conditions in a multi-anvil press. The method allows us to quantify 3D distributions of atomic hydrogen in μm dimensions. These self-calibrating measurements were carried out at the nuclear microprobe SNAKE at the Munich tandem accelerator lab using a 25 MeV proton microbeam. We provide hydrogen depth-profiles, hydrogen maps and H2O concentrations. Pp-scattering data and results from independent Raman and SIMS analyses are in good agreement. Water contents for a set of high-pressure polymorphs with varying Fe-concentrations range from 0

  19. Vapor deposition of water on graphitic surfaces: Formation of amorphous ice, bilayer ice, ice I, and liquid water

    SciTech Connect

    Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria

    2014-11-14

    Carbonaceous surfaces are a major source of atmospheric particles and could play an important role in the formation of ice. Here we investigate through molecular simulations the stability, metastability, and molecular pathways of deposition of amorphous ice, bilayer ice, and ice I from water vapor on graphitic and atomless Lennard-Jones surfaces as a function of temperature. We find that bilayer ice is the most stable ice polymorph for small cluster sizes, nevertheless it can grow metastable well above its region of thermodynamic stability. In agreement with experiments, the simulations predict that on increasing temperature the outcome of water deposition is amorphous ice, bilayer ice, ice I, and liquid water. The deposition nucleation of bilayer ice and ice I is preceded by the formation of small liquid clusters, which have two wetting states: bilayer pancake-like (wetting) at small cluster size and droplet-like (non-wetting) at larger cluster size. The wetting state of liquid clusters determines which ice polymorph is nucleated: bilayer ice nucleates from wetting bilayer liquid clusters and ice I from non-wetting liquid clusters. The maximum temperature for nucleation of bilayer ice on flat surfaces, T{sub B}{sup max} is given by the maximum temperature for which liquid water clusters reach the equilibrium melting line of bilayer ice as wetting bilayer clusters. Increasing water-surface attraction stabilizes the pancake-like wetting state of liquid clusters leading to larger T{sub B}{sup max} for the flat non-hydrogen bonding surfaces of this study. The findings of this study should be of relevance for the understanding of ice formation by deposition mode on carbonaceous atmospheric particles, including soot.

  20. Theory of water and charged liquid bridges.

    PubMed

    Morawetz, K

    2012-08-01

    The phenomenon of liquid bridge formation due to an applied electric field is investigated. A solution of a charged catenary is presented, which allows one to determine the static and dynamical stability conditions where charged liquid bridges are possible. The creeping height, the bridge radius and length, as well as the shape of the bridge are calculated showing an asymmetric profile, in agreement with observations. The flow profile is calculated from the Navier-Stokes equation leading to a mean velocity, which combines charge transport with neutral mass flow and which describes recent experiments on water bridges. PMID:23005849

  1. The Dipole Polarizability of a Water Molecule in Liquid Water

    NASA Astrophysics Data System (ADS)

    Distasio, Robert; Maitra, Rahul

    The dipole polarizability, α, provides a measure of the tendency of a molecule or material to deform (or polarize) in the presence of an electric field. Within the framework of density functional theory (DFT), we present a hierarchy of first principles based approaches for computing α of a molecule located in the condensed phase. This hierarchy includes a successive treatment of both short-range (hybridization, Pauli exchange-repulsion, etc.) and long-range (Coulomb) electrodynamical response screening in the computation of α, while simultaneously accounting for the surrounding condensed-phase environment. Utilizing highly accurate liquid water configurations generated from van der Waals inclusive hybrid DFT based ab initio molecular dynamics, we computed α for a given water molecule in liquid water as a first application of this approach. Our findings will be compared and contrasted with α computed for an isolated gas-phase water molecule.

  2. Liquid Hot Water Pretreatment of Cellulosic Biomass

    NASA Astrophysics Data System (ADS)

    Kim, Youngmi; Hendrickson, Rick; Mosier, Nathan S.; Ladisch, Michael R.

    Lignocellulosic biomass is an abundant and renewable resource for fuel ethanol production. However, the lignocellulose is recalcitrant to enzymatic hydrolysis because of its structural complexity. Controlled-pH liquid hot water (LHW) pretreatment of cellulosic feedstock improves its enzymatic digestibility by removing hemicellulose and making the cellulose more accessible to cellulase enzymes. The removed hemicellulose is solubilized in the liquid phase of the pretreated feedstock as oligosaccharides. Formation of monomeric sugars during the LHW pretreatment is minimal. The LHW pretreatment is carried out by cooking the feedstock in process water at temperatures between 160 and 190°C and at a pH of 4-7. No additional chemicals are needed. This chapter presents the detailed procedure of the LHW pretreatment of lignocellulosic biomass.

  3. Liquid water habitats on early Mars

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.; Davis, Wanda L.

    1992-01-01

    Although the Viking results may indicate that Mars has no life today, the possibility exists that Mars may hold the best record of the events that led to the origin of life. There is direct geomorphological evidence that in the past Mars had large amounts of liquid water on its surface. Atmospheric models would suggest that this early period of hydrological activity was due to the presence of a thick atmosphere and the resulting warmer temperatures. From a biological perspective the existence of liquid water by itself motivates the question of the origin of life on Mars. From studies of the Earth's earliest biosphere, we know that by 3.5 Gyr ago life had originated on Earth and reached a fair degree of biological sophistication. Surface activity and erosion on Earth make it difficult to trace the history of life before the 3.5 Gyr timeframe. If Mars did maintain a clement environment for longer than it took for life to originate on Earth, then the question of the origin of life on Mars follows naturally. Based upon simple models of the evolution of the Martian climate, we divide the history of liquid water habitats on the Martian surface into four epochs based upon the atmospheric temperature and pressure.

  4. Hydrogen-bond kinetics in liquid water

    NASA Astrophysics Data System (ADS)

    Luzar, Alenka; Chandler, David

    1996-01-01

    HYDROGEN bonds play a crucial role in the behaviour of water1-4 their spatial patterns and fluctuations characterize the structure and dynamics of the liquid5-7. The processes of breaking and making hydrogen bonds in the condensed phase can be probed indirectly by a variety of experimental techniques8, and more quantitative information can be obtained from computer simulations9. In particular, simulations have revealed that on long timescales the relaxation behaviour of hydrogen bonds in liquid water exhibit non-exponential kinetics7,10-13, suggesting that bond making and breaking are not simple processes characterized by well defined rate constants. Here we show that these kinetics can be understood in terms of an interplay between diffusion and hydrogen-bond dynamics. In our model, which can be extended to other hydrogen-bonded liquids, diffusion governs whether a specific pair of water molecules are near neighbours, and hydrogen bonds between such pairs form and persist at random with average lifetimes determined by rate constants for bond making and breaking.

  5. Liquid water and active resurfacing on Europa

    NASA Technical Reports Server (NTRS)

    Squyres, S. W.; Reynolds, R. T.; Cassen, P. M.; Peale, S. J.

    1983-01-01

    Arguments for recent resurfacing of Europa by H2O from a liquid layer are presented, based on new interpretations of recent spacecraft and earth-based observations and revised theoretical calculations. The heat flow in the core and shell due to tidal forces is discussed, and considerations of viscosity and convection in the interior are found to imply water retention in the outer 60 km or so of the silicates, forming a layer of water/ice many tens of km thick. The outer ice crust is considered to be too thin to support heat transport rates sufficient to freeze the underlying water. Observational evidence for the calculations would consist of an insulating layer of frosts derived from water boiling up between cracks in the surface crust. Evidence for the existence of such a frost layer, including the photometric function of Europa and the deposits of sulfur on the trailing hemisphere, is discussed.

  6. Glass polymorphism in glycerol-water mixtures: II. Experimental studies.

    PubMed

    Bachler, Johannes; Fuentes-Landete, Violeta; Jahn, David A; Wong, Jessina; Giovambattista, Nicolas; Loerting, Thomas

    2016-04-20

    We report a detailed experimental study of (i) pressure-induced transformations in glycerol-water mixtures at T = 77 K and P = 0-1.8 GPa, and (ii) heating-induced transformations of glycerol-water mixtures recovered at 1 atm and T = 77 K. Our samples are prepared by cooling the solutions at ambient pressure at various cooling rates (100 K s(-1)-10 K h(-1)) and for the whole range of glycerol mole fractions, χg. Depending on concentration and cooling rates, cooling leads to samples containing amorphous ice (χg ≥ 0.20), ice (χg ≤ 0.32), and/or "distorted ice" (0 < χg ≤ 0.38). Upon compression, we find that (a) fully vitrified samples at χg ≥ 0.20 do not show glass polymorphism, in agreement with previous works; (b) samples containing ice show pressure-induced amorphization (PIA) leading to the formation of high-density amorphous ice (HDA). PIA of ice domains within the glycerol-water mixtures is shown to be possible only up to χg ≈ 0.32 (T = 77 K). This is rather surprising since it has been known that at χg < 0.38, cooling leads to phase-separated samples with ice and maximally freeze-concentrated solution of χg ≈ 0.38. Accordingly, in the range 0.32 < χg < 0.38, we suggest that the water domains freeze into an interfacial ice, i.e., a highly-distorted form of layered ice, which is unable to transform to HDA upon compression. Upon heating samples recovered at 1 atm, we observe a rich phase behavior. Differential scanning calorimetry indicates that only at χg ≤ 0.15, the water domains within the sample exhibit polyamorphism, i.e., the HDA-to-LDA (low-density amorphous ice) transformation. At 0.15 < χg ≤ 0.38, samples contain ice, interfacial ice, and/or HDA domains. All samples (χg ≤ 0.38) show: the crystallization of amorphous ice domains, followed by the glass transition of the vitrified glycerol-water domains and, finally, the melting of ice at high temperatures. Our work exemplifies the complex "phase" behavior of glassy binary

  7. Glass polymorphism in glycerol–water mixtures: II. Experimental studies

    PubMed Central

    Bachler, Johannes; Fuentes-Landete, Violeta; Jahn, David A.; Wong, Jessina; Giovambattista, Nicolas

    2016-01-01

    We report a detailed experimental study of (i) pressure-induced transformations in glycerol–water mixtures at T = 77 K and P = 0–1.8 GPa, and (ii) heating-induced transformations of glycerol–water mixtures recovered at 1 atm and T = 77 K. Our samples are prepared by cooling the solutions at ambient pressure at various cooling rates (100 K s–1–10 K h–1) and for the whole range of glycerol mole fractions, χ g. Depending on concentration and cooling rates, cooling leads to samples containing amorphous ice (χ g ≥ 0.20), ice (χ g ≤ 0.32), and/or “distorted ice” (0 < χ g ≤ 0.38). Upon compression, we find that (a) fully vitrified samples at χ g ≥ 0.20 do not show glass polymorphism, in agreement with previous works; (b) samples containing ice show pressure-induced amorphization (PIA) leading to the formation of high-density amorphous ice (HDA). PIA of ice domains within the glycerol–water mixtures is shown to be possible only up to χ g ≈ 0.32 (T = 77 K). This is rather surprising since it has been known that at χ g < 0.38, cooling leads to phase-separated samples with ice and maximally freeze-concentrated solution of χ g ≈ 0.38. Accordingly, in the range 0.32 < χ g < 0.38, we suggest that the water domains freeze into an interfacial ice, i.e., a highly-distorted form of layered ice, which is unable to transform to HDA upon compression. Upon heating samples recovered at 1 atm, we observe a rich phase behavior. Differential scanning calorimetry indicates that only at χ g ≤ 0.15, the water domains within the sample exhibit polyamorphism, i.e., the HDA-to-LDA (low-density amorphous ice) transformation. At 0.15 < χ g ≤ 0.38, samples contain ice, interfacial ice, and/or HDA domains. All samples (χ g ≤ 0.38) show: the crystallization of amorphous ice domains, followed by the glass transition of the vitrified glycerol–water domains and, finally, the melting of ice at high temperatures. Our work exemplifies the complex

  8. Water in Room Temperature Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Fayer, Michael

    2014-03-01

    Room temperature ionic liquids (or RTILs, salts with a melting point below 25 °C) have become a subject of intense study over the last several decades. Currently, RTIL application research includes synthesis, batteries, solar cells, crystallization, drug delivery, and optics. RTILs are often composed of an inorganic anion paired with an asymmetric organic cation which contains one or more pendant alkyl chains. The asymmetry of the cation frustrates crystallization, causing the salt's melting point to drop significantly. In general, RTILs are very hygroscopic, and therefore, it is of interest to examine the influence of water on RTIL structure and dynamics. In addition, in contrast to normal aqueous salt solutions, which crystallize at low water concentration, in an RTIL it is possible to examine isolated water molecules interacting with ions but not with other water molecules. Here, optical heterodyne-detected optical Kerr effect (OHD-OKE) measurements of orientational relaxation on a series of 1-alkyl-3-methylimidazolium tetrafluoroborate RTILs as a function of chain length and water concentration are presented. The addition of water to the longer alkyl chain RTILs causes the emergence of a long time bi-exponential orientational anisotropy decay. Such decays have not been seen previously in OHD-OKE experiments on any type of liquid and are analyzed here using a wobbling-in-a-cone model. The orientational relaxation is not hydrodynamic, with the slowest relaxation component becoming slower as the viscosity decreases for the longest chain, highest water content samples. The dynamics of isolated D2O molecules in 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) were examined using two dimensional infrared (2D IR) vibrational echo spectroscopy. Spectral diffusion and incoherent and coherent transfer of excitation between the symmetric and antisymmetric modes are examined. The coherent transfer experiments are used to address the nature of inhomogeneous

  9. Liquid and glass polymorphism in a monatomic system with isotropic, smooth pair interactions.

    PubMed

    Abraham, Joel Y; Buldyrev, Sergey V; Giovambattista, Nicolas

    2011-12-01

    Systems of particles with interactions given by the Jagla core-softened pair potential are known to exhibit water-like thermodynamic anomalies and a liquid-liquid phase transition. The drawback of the Jagla potential is that it is characterized by discontinuous forces acting between particles and thus is not suitable for standard molecular dynamics (MD) simulations. Here we introduce a smooth version of the Jagla potential based on two Fermi distributions and study the properties of a system of particles interacting via this new "Fermi-Jagla" pair potential by using standard MD simulations. We find that the liquid based on the Fermi-Jagla potential retains most of the properties of the liquid based on the original Jagla potential. Namely, it exhibits the following water-like anomalies: (i) decrease of density, (ii) increase of compressibility, κ(T)(T,P), and (iii) increase of isobaric specific heat, C(P)(T,P), upon isobaric cooling, and (iv) increase of diffusivity upon isothermal compression. The Fermi-Jagla potential also exhibits (i') density minima, (ii') compressibility minima, (iii') isobaric specific heat minima upon isobaric cooling, and (iv') diffusivity minima upon isothermal compression. As in the Jagla model case, we find a liquid-liquid phase transition (LLPT) and a liquid-liquid critical point in the equilibrium liquid. Contrary to the case of the original Jagla model liquid, the LLPT line for the Fermi-Jagla potential has a negative slope in the P-T plane that extends well above the crystallization temperature. This feature makes the Fermi-Jagla potential a better candidate to reproduce the behavior of tetrahedral liquids including water, for which the LLPT line observed in simulations has also negative slope. In the glass state, the Fermi-Jagla pair potential results in reversible polyamorphism between low- and high-density amorphous solids (LDA and HDA, respectively). We also find that HDA results from pressure-induced amorphization of the model

  10. The polymorphic phases of the hexaalkanoyloxytriphenylene liquid crystals, as studied by deuterium NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Goldfarb, D.; Lifshitz, E.; Zimmermann, H.; Luz, Z.

    1985-06-01

    Deuterium NMR spectra are reported for several specifically deuterated hexaalkanoyloxytriphenylenes in their corresponding liquid crystalline phases. The higher homologs of this series are polymorphic and exhibit a variety of discotic mesophases, including both biaxial (D0 and D1) and uniaxial (D2) columnar phases. The ordering characteristics of these phases are studied using the quadrupolar splittings of the aromatic and aliphatic deuterons. The results show that during the transition from the biaxial D1 to the axial D2 phase the major susceptibility tensor switch orientation, apparently due to strong tilting of the molecules with respect to the columnar axis in the biaxial phase. Characteristic features which appear in the spectra of these phases are interpreted in terms of intercolumnar jumps of mesogen molecules.

  11. Triplet correlation functions in liquid water

    NASA Astrophysics Data System (ADS)

    Dhabal, Debdas; Singh, Murari; Wikfeldt, Kjartan Thor; Chakravarty, Charusita

    2014-11-01

    Triplet correlations have been shown to play a crucial role in the transformation of simple liquids to anomalous tetrahedral fluids [M. Singh, D. Dhabal, A. H. Nguyen, V. Molinero, and C. Chakravarty, Phys. Rev. Lett. 112, 147801 (2014)]. Here we examine triplet correlation functions for water, arguably the most important tetrahedral liquid, under ambient conditions, using configurational ensembles derived from molecular dynamics (MD) simulations and reverse Monte Carlo (RMC) datasets fitted to experimental scattering data. Four different RMC data sets with widely varying hydrogen-bond topologies fitted to neutron and x-ray scattering data are considered [K. T. Wikfeldt, M. Leetmaa, M. P. Ljungberg, A. Nilsson, and L. G. M. Pettersson, J. Phys. Chem. B 113, 6246 (2009)]. Molecular dynamics simulations are performed for two rigid-body effective pair potentials (SPC/E and TIP4P/2005) and the monatomic water (mW) model. Triplet correlation functions are compared with other structural measures for tetrahedrality, such as the O-O-O angular distribution function and the local tetrahedral order distributions. In contrast to the pair correlation functions, which are identical for all the RMC ensembles, the O-O-O triplet correlation function can discriminate between ensembles with different degrees of tetrahedral network formation with the maximally symmetric, tetrahedral SYM dataset displaying distinct signatures of tetrahedrality similar to those obtained from atomistic simulations of the SPC/E model. Triplet correlations from the RMC datasets conform closely to the Kirkwood superposition approximation, while those from MD simulations show deviations within the first two neighbour shells. The possibilities for experimental estimation of triplet correlations of water and other tetrahedral liquids are discussed.

  12. Triplet correlation functions in liquid water

    SciTech Connect

    Dhabal, Debdas; Chakravarty, Charusita; Singh, Murari; Wikfeldt, Kjartan Thor

    2014-11-07

    Triplet correlations have been shown to play a crucial role in the transformation of simple liquids to anomalous tetrahedral fluids [M. Singh, D. Dhabal, A. H. Nguyen, V. Molinero, and C. Chakravarty, Phys. Rev. Lett. 112, 147801 (2014)]. Here we examine triplet correlation functions for water, arguably the most important tetrahedral liquid, under ambient conditions, using configurational ensembles derived from molecular dynamics (MD) simulations and reverse Monte Carlo (RMC) datasets fitted to experimental scattering data. Four different RMC data sets with widely varying hydrogen-bond topologies fitted to neutron and x-ray scattering data are considered [K. T. Wikfeldt, M. Leetmaa, M. P. Ljungberg, A. Nilsson, and L. G. M. Pettersson, J. Phys. Chem. B 113, 6246 (2009)]. Molecular dynamics simulations are performed for two rigid-body effective pair potentials (SPC/E and TIP4P/2005) and the monatomic water (mW) model. Triplet correlation functions are compared with other structural measures for tetrahedrality, such as the O–O–O angular distribution function and the local tetrahedral order distributions. In contrast to the pair correlation functions, which are identical for all the RMC ensembles, the O–O–O triplet correlation function can discriminate between ensembles with different degrees of tetrahedral network formation with the maximally symmetric, tetrahedral SYM dataset displaying distinct signatures of tetrahedrality similar to those obtained from atomistic simulations of the SPC/E model. Triplet correlations from the RMC datasets conform closely to the Kirkwood superposition approximation, while those from MD simulations show deviations within the first two neighbour shells. The possibilities for experimental estimation of triplet correlations of water and other tetrahedral liquids are discussed.

  13. Metastable liquid-liquid transition in a molecular model of water

    NASA Astrophysics Data System (ADS)

    Palmer, Jeremy C.; Martelli, Fausto; Liu, Yang; Car, Roberto; Panagiotopoulos, Athanassios Z.; Debenedetti, Pablo G.

    2014-06-01

    Liquid water's isothermal compressibility and isobaric heat capacity, and the magnitude of its thermal expansion coefficient, increase sharply on cooling below the equilibrium freezing point. Many experimental, theoretical and computational studies have sought to understand the molecular origin and implications of this anomalous behaviour. Of the different theoretical scenarios put forward, one posits the existence of a first-order phase transition that involves two forms of liquid water and terminates at a critical point located at deeply supercooled conditions. Some experimental evidence is consistent with this hypothesis, but no definitive proof of a liquid-liquid transition in water has been obtained to date: rapid ice crystallization has so far prevented decisive measurements on deeply supercooled water, although this challenge has been overcome recently. Computer simulations are therefore crucial for exploring water's structure and behaviour in this regime, and have shown that some water models exhibit liquid-liquid transitions and others do not. However, recent work has argued that the liquid-liquid transition has been mistakenly interpreted, and is in fact a liquid-crystal transition in all atomistic models of water. Here we show, by studying the liquid-liquid transition in the ST2 model of water with the use of six advanced sampling methods to compute the free-energy surface, that two metastable liquid phases and a stable crystal phase exist at the same deeply supercooled thermodynamic condition, and that the transition between the two liquids satisfies the thermodynamic criteria of a first-order transition. We follow the rearrangement of water's coordination shell and topological ring structure along a thermodynamically reversible path from the low-density liquid to cubic ice. We also show that the system fluctuates freely between the two liquid phases rather than crystallizing. These findings provide unambiguous evidence for a liquid-liquid transition in

  14. Metastable liquid-liquid transition in a molecular model of water.

    PubMed

    Palmer, Jeremy C; Martelli, Fausto; Liu, Yang; Car, Roberto; Panagiotopoulos, Athanassios Z; Debenedetti, Pablo G

    2014-06-19

    Liquid water's isothermal compressibility and isobaric heat capacity, and the magnitude of its thermal expansion coefficient, increase sharply on cooling below the equilibrium freezing point. Many experimental, theoretical and computational studies have sought to understand the molecular origin and implications of this anomalous behaviour. Of the different theoretical scenarios put forward, one posits the existence of a first-order phase transition that involves two forms of liquid water and terminates at a critical point located at deeply supercooled conditions. Some experimental evidence is consistent with this hypothesis, but no definitive proof of a liquid-liquid transition in water has been obtained to date: rapid ice crystallization has so far prevented decisive measurements on deeply supercooled water, although this challenge has been overcome recently. Computer simulations are therefore crucial for exploring water's structure and behaviour in this regime, and have shown that some water models exhibit liquid-liquid transitions and others do not. However, recent work has argued that the liquid-liquid transition has been mistakenly interpreted, and is in fact a liquid-crystal transition in all atomistic models of water. Here we show, by studying the liquid-liquid transition in the ST2 model of water with the use of six advanced sampling methods to compute the free-energy surface, that two metastable liquid phases and a stable crystal phase exist at the same deeply supercooled thermodynamic condition, and that the transition between the two liquids satisfies the thermodynamic criteria of a first-order transition. We follow the rearrangement of water's coordination shell and topological ring structure along a thermodynamically reversible path from the low-density liquid to cubic ice. We also show that the system fluctuates freely between the two liquid phases rather than crystallizing. These findings provide unambiguous evidence for a liquid-liquid transition in

  15. Liquid-liquid transition in ST2 water

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Palmer, Jeremy C.; Panagiotopoulos, Athanassios Z.; Debenedetti, Pablo G.

    2012-12-01

    We use the weighted histogram analysis method [S. Kumar, D. Bouzida, R. H. Swendsen, P. A. Kollman, and J. M. Rosenberg, J. Comput. Chem. 13, 1011 (1992), 10.1002/jcc.540130812] to calculate the free energy surface of the ST2 model of water as a function of density and bond-orientational order. We perform our calculations at deeply supercooled conditions (T = 228.6 K, P = 2.2 kbar; T = 235 K, P = 2.2 kbar) and focus our attention on the region of bond-orientational order that is relevant to disordered phases. We find a first-order transition between a low-density liquid (LDL, ρ ≈ 0.9 g/cc) and a high-density liquid (HDL, ρ ≈ 1.15 g/cc), confirming our earlier sampling of the free energy surface of this model as a function of density [Y. Liu, A. Z. Panagiotopoulos, and P. G. Debenedetti, J. Chem. Phys. 131, 104508 (2009), 10.1063/1.3229892]. We demonstrate the disappearance of the LDL basin at high pressure and of the HDL basin at low pressure, in agreement with independent simulations of the system's equation of state. Consistency between directly computed and reweighted free energies, as well as between free energy surfaces computed using different thermodynamic starting conditions, confirms proper equilibrium sampling. Diffusion and structural relaxation calculations demonstrate that equilibration of the LDL phase, which exhibits slow dynamics, is attained in the course of the simulations. Repeated flipping between the LDL and HDL phases in the course of long molecular dynamics runs provides further evidence of a phase transition. We use the Ewald summation with vacuum boundary conditions to calculate long-ranged Coulombic interactions and show that conducting boundary conditions lead to unphysical behavior at low temperatures.

  16. Polarized View of Supercooled Liquid Water Clouds

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Cairns, Brian; Van Diedenhoven, Bastiaan; Ackerman, Andrew S.; Wasilewski, Andrzej P.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Platnick, Steven E.; Arnold, G. Thomas

    2016-01-01

    Supercooled liquid water (SLW) clouds, where liquid droplets exist at temperatures below 0 C present a well known aviation hazard through aircraft icing, in which SLW accretes on the airframe. SLW clouds are common over the Southern Ocean, and climate-induced changes in their occurrence is thought to constitute a strong cloud feedback on global climate. The two recent NASA field campaigns POlarimeter Definition EXperiment (PODEX, based in Palmdale, California, January-February 2013) and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, based in Houston, Texas in August- September 2013) provided a unique opportunity to observe SLW clouds from the high-altitude airborne platform of NASA's ER-2 aircraft. We present an analysis of measurements made by the Research Scanning Polarimeter (RSP) during these experiments accompanied by correlative retrievals from other sensors. The RSP measures both polarized and total reflectance in 9 spectral channels with wavelengths ranging from 410 to 2250 nm. It is a scanning sensor taking samples at 0.8deg intervals within 60deg from nadir in both forward and backward directions. This unique angular resolution allows for characterization of liquid water droplet size using the rainbow structure observed in the polarized reflectances in the scattering angle range between 135deg and 165deg. Simple parametric fitting algorithms applied to the polarized reflectance provide retrievals of the droplet effective radius and variance assuming a prescribed size distribution shape (gamma distribution). In addition to this, we use a non-parametric method, Rainbow Fourier Transform (RFT),which allows retrieval of the droplet size distribution without assuming a size distribution shape. We present an overview of the RSP campaign datasets available from the NASA GISS website, as well as two detailed examples of the retrievals. In these case studies we focus on cloud fields with spatial features

  17. Liquid-liquid and liquid-solid equilibria of systems containing water and selected chlorophenols

    SciTech Connect

    Jaoui, M.; Luszczyk, M.; Rogalski, M.

    1999-12-01

    Chlorinated phenols are present in effluents of oil refinery, coal mining, plastic, leather, paint, and pharmaceutical industrial plants. The solubilities of phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol in water were determined in the temperature range between 270 K and 423 K. Dynamic thermal analysis and a visual static method were used to establish the phase diagrams. Results obtained over a wide temperature and concentration range were used to model the liquid-liquid coexistence curve of the systems studied.

  18. Evidence for Recent Liquid Water on Mars

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Newton Crater is a large basin formed by an asteroid impact that probably occurred more than 3 billion years ago. It is approximately 287 kilometers (178 miles) across. The picture shown here (top) highlights the north wall of a specific, smaller crater located in the southwestern quarter of Newton Crater (above). The crater of interest was also formed by an impact; it is about 7 km (4.4 mi) across, which is about 7 times bigger than the famous Meteor Crater in northern Arizona in North America. The north wall of the small crater has many narrow gullies eroded into it. These are hypothesized to have been formed by flowing water and debris flows. Debris transported with the water created lobed and finger-like deposits at the base of the crater wall where it intersects the floor (bottom center top image). Many of the finger-like deposits have small channels indicating that a liquid, most likely water, flowed in these areas. Hundreds of individual water and debris flow events might have occurred to create the scene shown here. Each outburst of water from higher up on the crater slopes would have constituted a competition between evaporation, freezing, and gravity. The individual deposits at the ends of channels in this MOC image mosaic were used to get a rough estimate of the minimum amount of water that might be involved in each flow event. This is done first by assuming that the deposits are like debris flows on Earth. In a debris flow, no less than about 10% (and no more than 30%) of their volume is water. Second, the volume of an apron deposit is estimated by measuring the area covered in the MOC image and multiplying it by a conservative estimate of thickness, 2 meters (6.5 feet). For a flow containing only 10% water, these estimates conservatively suggest that about 2.5 million liters (660,000 gallons) of water are involved in each event; this is enough to fill about 7 community-sized swimming pools or enough to supply 20 people with their water needs for a year

  19. Displacement of nonwetting liquids from unsaturated sands by water infiltration

    SciTech Connect

    Boley, T.M.; Overcamp, T.J.

    1998-09-01

    Accidental spills of nonwetting or nonaqueous phase liquids (NAPLs) onto land can lead to ground water contamination. Once a spill has occurred, liquid infiltrates downward under the influence of gravity. As the infiltration continues, capillary forces retain a portion of the immiscible liquid within the pore spaces. After infiltration ceases, the liquid remaining within the pores is termed the residual liquid, which is frequently expressed as a percentage of the total pore volume. The quantity of residual liquid retained depends on soil and liquid properties. Xylene was spilled onto moist glass beads or various moist sands and water was trickled onto the columns every eight hours for periods up to 10 days. The xylene residual in the columns with water infiltration decreased compared to those of control columns, indicating a downward displacement of xylene. The extent of displacement increased with increasing size of the porous media and with increasing amounts of water infiltration.

  20. Vibrational Quantum Decoherence in Liquid Water.

    PubMed

    Joutsuka, Tatsuya; Thompson, Ward H; Laage, Damien

    2016-02-18

    Traditional descriptions of vibrational energy transfer consider a quantum oscillator interacting with a classical environment. However, a major limitation of this simplified description is the neglect of quantum decoherence induced by the different interactions between two distinct quantum states and their environment, which can strongly affect the predicted energy-transfer rate and vibrational spectra. Here, we use quantum-classical molecular dynamics simulations to determine the vibrational quantum decoherence time for an OH stretch vibration in liquid heavy water. We show that coherence is lost on a sub-100 fs time scale due to the different responses of the first shell neighbors to the ground and excited OH vibrational states. This ultrafast decoherence induces a strong homogeneous contribution to the linear infrared spectrum and suggests that resonant vibrational energy transfer in H2O may be more incoherent than previously thought. PMID:26807717

  1. Liquid Water vs. Hydrogen Cyanide on Enceladus

    NASA Astrophysics Data System (ADS)

    Glein, C. R.; Zolotov, M. Y.; Shock, E. L.

    2008-12-01

    The Ion and Neutral Mass Spectrometer onboard the Cassini spacecraft detected hydrogen cyanide (HCN) in plumes on Enceladus [1]. We explored computationally the thermodynamic stability and kinetic reactivity of HCN. Thermochemical equilibrium calculations show that HCN is unstable in liquid water, and should be overwhelmingly hydrolyzed to formic acid (HCOOH) and ammonia (NH3) under all conditions relevant to Enceladus. Even in an aqueous solution with an unreasonably high NH3 activity of 10, the HCOOH/HCN activity ratio is predicted to be greater than 107 at 0°C. This ratio decreases with increasing NH3 activity and with increasing temperature. Even at high temperatures (e.g., 200°C), it is at least 3-4 orders-of-magnitude above unity. It is notable that neither formic acid nor ammonia have been detected in any plumes [1]. We thus infer that the detected HCN is unlikely to have equilibrated with an aqueous solution below Enceladus' surface. Chemical kinetic considerations indicate that the hydrolysis lifetime of HCN has a complex dependence on pH, and decreases with increasing temperature. We find that, even at the pH value most conducive to the survival of HCN (~5), HCN can persist for only about 5 Ma in liquid water at 0°C. Thus, the HCN in the plumes could not have come from a long-lasting ocean or sea, and probably came from a recent aqueous melt or some icy phase. A liquid source for the HCN would be more restrictive than an ice source. For example, an aqueous solution must have a pH between 4-6 for HCN to be preserved in it for at least ~1 Ma at 0°C. However, this pH restriction would be lifted if the HCN source were a very young pool (i.e., centuries-millennia old). On the other hand, it is expected that HCN could survive indefinitely in an icy matrix. The proposed HCN sources may be less favorable abodes for life than a long-lived aqueous reservoir. Reference: [1] Waite J.H. et al. (2008) Eur. Planet. Sci. Congr. 3, EPSC2008-A-00593.

  2. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    NASA Astrophysics Data System (ADS)

    Fadeeva, Tatiana A.; Husson, Pascale; DeVine, Jessalyn A.; Costa Gomes, Margarida F.; Greenbaum, Steven G.; Castner, Edward W.

    2015-08-01

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies.

  3. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    SciTech Connect

    Fadeeva, Tatiana A.; DeVine, Jessalyn A.; Castner, Edward W.; Husson, Pascale; Costa Gomes, Margarida F.; Greenbaum, Steven G.

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies.

  4. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids.

    PubMed

    Fadeeva, Tatiana A; Husson, Pascale; DeVine, Jessalyn A; Costa Gomes, Margarida F; Greenbaum, Steven G; Castner, Edward W

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies. PMID:26277141

  5. Evidence for Recent Liquid Water on Mars

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This image, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2000 shows numerous examples of martian gullies that all start--or head--in a specific layer roughly a hundred meters beneath the surface of Mars. These features are located on the south-facing wall of a trough in the Gorgonum Chaos region, an area found to have many examples of gullies proposed to have formed by seepage and runoff of liquid water in recent martian times. The layer from which the gullies emanate has recessed backward to form an overhang beneath a harder layer of rock. The larger gullies have formed an alcove--an area above the overhang from which debris has collapsed to leave a dark-toned scar. Below the layer of seepage is found a dark, narrow channel that runs down the slope to an apron of debris. The small, bright, parallel features at the base of the cliff at the center-right of the picture is a series of large windblown ripples. Although the dark tone of the alcoves and channels in this image is not likely to be the result of wet ground (the contrast in this image has been enhanced), it does suggest that water has seeped out of the ground and moved down the slope quite recently. Sharp contrasts between dark and light areas are hard to maintain on Mars for very long periods of time because dust tends to coat surfaces and reduce brightness differences. To keep dust from settling on a surface, it has to have undergone some process of erosion (wind, landslides, water runoff) relatively recently. There is no way to know how recent this activity was, but educated guesses center between a few to tens of years, and it is entirely possible that the area shown in this image has water seeping out of the ground today. Centered near 37.9S, 170.2W, sunlight illuminates the MOC image from the upper left, north is toward the upper right. The context view above is from the Viking 1 orbiter and was acquired in 1977. The Viking picture is illuminated from the upper right

  6. Long-term evolution of transient liquid water on Mars

    NASA Astrophysics Data System (ADS)

    Richardson, Mark I.; Mischna, Michael A.

    2005-03-01

    Liquid water is not currently stable on the surface of Mars; however, transient liquid water (ice melt) may occur if the surface temperature is between the melting and boiling points. Such conditions are met on Mars with current surface pressures and obliquity due to the large diurnal range of surface temperatures. This yields the potential for transient, nonequilibrium liquid water. A general circulation model is used to undertake an initial exploration of the variation of this ``transient liquid water potential'' (TLWP) for different obliquities and over a range of increased pressures representing progressively earlier phases of Martian geological history. At higher obliquities and slightly higher surface pressures (<50 mbar), TLWP conditions are met over a very large fraction of the planet. As the surface pressure is increased above about 50-100 mbar, however, increased atmospheric thermal blanketing reduces the diurnal surface temperature range, essentially eliminating the possibility of even transient liquid water. At high enough pressures, the mean temperature is sufficiently elevated to allow stable liquid water. Thus the potential for liquid water on Mars has not decreased monotonically over planetary history as the atmosphere was lost. Instead, a distinct minimum in TLWP (the ``dead zone'') will have occurred during the extended period for which pressures were in the middle range between about 0.1 and 1 bar. This has direct and restrictive implications for chemical weathering and life. The fundamental conclusion of this study is largely insensitive to invocation of brines and to more detailed treatment of atmospheric radiative processes.

  7. Anatomy of competing quantum effects in liquid water.

    NASA Astrophysics Data System (ADS)

    Ramirez, Rafa; Ganeshan, Sriram; Fernandez-Serra, M. V.

    2013-03-01

    ct- Molecules like water have vibrational modes with zero point energy well above room temperature. As a consequence, classical molecular dynamics simulations of liquid water largely underestimate the kinetic energy of the ions, which translates into an underestimation of covalent interatomic distances. In this work, we show that it is possible to apply generalized Langevin equation with suppressed noise in combination with Nose-Hoover thermostats to achieve an efficient zero-point temperature of independent modes of liquid water. Using this method we deconstruct the competing quantum effects in liquid water. We demonstrate how the structure and dynamical modes of liquid water respond to non-equilibrium distribution of zero point temperatures on the normal modes.

  8. Thermoluminescence dosimetry measurements of brachytherapy sources in liquid water

    SciTech Connect

    Tailor, Ramesh; Tolani, Naresh; Ibbott, Geoffrey S.

    2008-09-15

    Radiation therapy dose measurements are customarily performed in liquid water. The characterization of brachytherapy sources is, however, generally based on measurements made with thermoluminescence dosimeters (TLDs), for which contact with water may lead to erroneous readings. Consequently, most dosimetry parameters reported in the literature have been based on measurements in water-equivalent plastics, such as Solid Water. These previous reports employed a correction factor to transfer the dose measurements from a plastic phantom to liquid water. The correction factor most often was based on Monte Carlo calculations. The process of measuring in a water-equivalent plastic phantom whose exact composition may be different from published specifications, then correcting the results to a water medium leads to increased uncertainty in the results. A system has been designed to enable measurements with TLDs in liquid water. This system, which includes jigs to support water-tight capsules of lithium fluoride in configurations suitable for measuring several dosimetric parameters, was used to determine the correction factor from water-equivalent plastic to water. Measurements of several {sup 125}I and {sup 131}Cs prostate brachytherapy sources in liquid water and in a Solid Water phantom demonstrated a correction factor of 1.039{+-}0.005 at 1 cm distance. These measurements are in good agreement with a published value of this correction factor for an {sup 125}I source.

  9. Space Station Water Processor Mostly Liquid Separator (MLS)

    NASA Technical Reports Server (NTRS)

    Lanzarone, Anthony

    1995-01-01

    This report presents the results of the development testing conducted under this contract to the Space Station Water Processor (WP) Mostly Liquid Separator (MLS). The MLS units built and modified during this testing demonstrated acceptable air/water separation results in a variety of water conditions with inlet flow rates ranging from 60 - 960 LB/hr.

  10. Effect of hydrophobic environments on the hypothesized liquid-liquid critical point of water.

    PubMed

    Strekalova, Elena G; Corradini, Dario; Mazza, Marco G; Buldyrev, Sergey V; Gallo, Paola; Franzese, Giancarlo; Stanley, H Eugene

    2012-01-01

    The complex behavior of liquid water, along with its anomalies and their crucial role in the existence of life, continue to attract the attention of researchers. The anomalous behavior of water is more pronounced at subfreezing temperatures and numerous theoretical and experimental studies are directed towards developing a coherent thermodynamic and dynamic framework for understanding supercooled water. The existence of a liquid-liquid critical point in the deep supercooled region has been related to the anomalous behavior of water. However, the experimental study of supercooled water at very low temperatures is hampered by the homogeneous nucleation of the crystal. Recently, water confined in nanoscopic structures or in solutions has attracted interest because nucleation can be delayed. These systems have a tremendous relevance also for current biological advances; e.g., supercooled water is often confined in cell membranes and acts as a solvent for biological molecules. In particular, considerable attention has been recently devoted to understanding hydrophobic interactions or the behavior of water in the presence of apolar interfaces due to their fundamental role in self-assembly of micelles, membrane formation and protein folding. This article reviews and compares two very recent computational works aimed at elucidating the changes in the thermodynamic behavior in the supercooled region and the liquid-liquid critical point phenomenon for water in contact with hydrophobic environments. The results are also compared to previous reports for water in hydrophobic environments. PMID:23277673

  11. Factors that Determine Zeolite Stability in Hot Liquid Water.

    PubMed

    Zhang, Lu; Chen, Kuizhi; Chen, Banghao; White, Jeffery L; Resasco, Daniel E

    2015-09-16

    The susceptibility of zeolites to hot liquid water may hamper their full utilization in aqueous phase processes, such as those involved in biomass conversion and upgrading reactions. Interactions of zeolites with water strongly depend on the presence of hydrophilic moieties including Brønsted acid sites (BAS), extraframework cations, and silanol defects, which facilitate wetting of the surface. However, it is not clear which of these moieties are responsible for the susceptibility of zeolites to liquid water. Previous studies have offered contradictory explanations because the role of each of these characteristics has not been investigated independently. In this work, a systematic comparison has been attempted by relating crystallinity losses to the variation of each of the five zeolite characteristics that may influence their stability in liquid water, including number of BAS, Si-O-Si bonds, framework type, silanol defects, and extraframework Al. In this study, we have systematically monitored the crystallinity changes of a series of HY, H-ZSM-5, and H-β zeolite samples with varying Si/Al ratio, density of BAS, zeolite structure, and density of silanol defects upon exposure to liquid water at 200 °C. The results of this comparison unambiguously indicate that the density of silanol defects plays the most crucial role in determining susceptibility of zeolites to hot liquid water. By functionalizing the silanol defects with organosilanes, the hydrophobicity of defective zeolite is increased and the tolerance to hot liquid water is significantly enhanced. PMID:26301890

  12. Liquid water in the domain of cubic crystalline ice Ic

    NASA Technical Reports Server (NTRS)

    Jenniskens, P.; Banham, S. F.; Blake, D. F.; McCoustra, M. R.

    1997-01-01

    Vapor-deposited amorphous water ice when warmed above the glass transition temperature (120-140 K), is a viscous liquid which exhibits a viscosity vs temperature relationship different from that of liquid water at room temperature. New studies of thin water ice films now demonstrate that viscous liquid water persists in the temperature range 140-210 K. where it coexists with cubic crystalline ice. The liquid character of amorphous water above the glass transition is demonstrated by (1) changes in the morphology of water ice films on a nonwetting surface observed in transmission electron microscopy (TEM) at around 175 K during slow warming, (2) changes in the binding energy of water molecules measured in temperature programmed desorption (TPD) studies, and (3) changes in the shape of the 3.07 micrometers absorption band observed in grazing angle reflection-absorption infrared spectroscopy (RAIRS) during annealing at high temperature. whereby the decreased roughness of the water surface is thought to cause changes in the selection rules for the excitation of O-H stretch vibrations. Because it is present over such a wide range of temperatures, we propose that this form of liquid water is a common material in nature. where it is expected to exist in the subsurface layers of comets and on the surfaces of some planets and satellites.

  13. Two Calorimetrically Distinct States of Liquid Water Below 150 Kelvin

    PubMed

    Johari; Hallbrucker; Mayer

    1996-07-01

    Vapor-deposited amorphous solid and hyperquenched glassy water were found to irreversibly transform, on compression at 77 kelvin, to a high-density amorphous solid. On heating at atmospheric pressure, this solid became viscous water (water B), with a reversible glass-liquid transition onset at 129 +/- 2 kelvin. A different form of viscous water (water A) was formed by heating the uncompressed vapor-deposited amorphous solid and hyperquenched liquid water. On thermal cycling up to 148 kelvin, water B remained kinetically and thermodynamically distinct from water A. The occurrence of these two states, which do not interconvert, helps explain both the configurational relaxation of water and stress-induced amorphization. PMID:8688057

  14. Evidence for Recent Liquid Water on Mars

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Gullies eroded into the wall of a meteor impact crater in Noachis Terra. This high resolution view (top left) from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) shows channels and associated aprons of debris that are interpreted to have formed by groundwater seepage, surface runoff, and debris flow. The lack of small craters superimposed on the channels and apron deposits indicates that these features are geologically young. It is possible that these gullies indicate that liquid water is present within the martian subsurface today. The MOC image was acquired on September 28, 1999. The scene covers an area approximately 3 kilometers (1.9 miles) wide by 6.7 km (4.1 mi) high (note, the aspect ratio is 1.5 to 1.0). Sunlight illuminates this area from the upper left. The image is located near 54.8S, 342.5W. The context image (above) shows the location of the MOC image on the south-facing wall of an impact crater approximately 20 kilometers (12 miles) in diameter. The context picture was obtained by the Viking 1 orbiter in 1980 and is illuminated from the upper left. The large mound on the floor of the crater in the context view is a sand dune field. The Mars Orbiter Camera high resolution images are taken black-and-white (grayscale); the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s. A brief description of how the color was generated: The MOC narrow angle camera only takes grayscale (black and white) pictures. To create the color versions seen here, we have taken much lower resolution red and blue images acquired by the MOC's wide angle cameras, and by the Viking Orbiter cameras in the 1970s, synthesized a green image by averaging red and blue, and created a pallete of colors that represent the range of colors on Mars. We then use a relationship that correlates color and brightness to assign a color to each gray level. This is only a crude approximation of

  15. Water: The Liquid of Life. Fifth Grade.

    ERIC Educational Resources Information Center

    Illinois State Environmental Protection Agency, Springfield.

    These materials are for use by elementary and middle school teachers in the state of Illinois. This document contains five modules for teaching water conservation. Topics include: (1) "Life Depends on Water,""What is Water?" and "The Hydrologic Cycle"; (2) "The Treatment of Drinking Water"; (3) "Wastewater Treatment"; (4) "Earth's Closed…

  16. Determination of liquid water altitudes using combined remote sensors

    SciTech Connect

    Politovich, M.K.

    1995-09-01

    Methods by which altitude ranges of supercooled cloud liquid water in the atmosphere may be estimated are explored using measurements from a combination of ground-based remote sensors. The tests were conducted as part of the Winter Icing and Storms Project that took place in eastern Colorado during the winters of 1990, 1991, and 1993. The basic method augments microwave radiometer measurements of path-integrated liquid water with observations from additional remote sensors to establish height limits for the supercooled liquid. One variation uses a simple adiabatic parcel lifting model initiated at a cloud-base height determined from a ceilometer, temperature and pressure from a radio acoustic sounding system or rawinsonde, and combines these with the radiometer`s total liquid measurement to obtain an estimate of the liquid cloud-top height. Since it does not account for liquid loss by entrainment or ice-liquid interaction processes, this method tends to underestimate the true liquid cloud top; for two cases examined in detail, 54% of icing pilot reports in the area were from above this estimated height. Some error is introduced due to differences in sampling locations and from horizontal variability in liquid water content. Vertical cloud boundaries from a K{sub a}-band radar were also used in the study; these often indicated thicker clouds than the liquid-layer depths observed from research aircraft, possibly due to the ambiguity of the ice-liquid phase distinction. Comparisons of liquid vertical profiles are presented, using normalized profile shapes based on uniform, adiabatic, and aircraft-derived composite assumptions. The adiabatic and climatological profile shapes generally agreed well with measurements from a research aircraft and were more realistic than the uniform profile. Suggestions for applications of these results toward a real-time aviation hazard identification system are presented. 30 refs., 11 figs., 5 tabs.

  17. The determination of water in biomass-derived liquid fuels

    SciTech Connect

    Roy, C.; De Caumia, B.

    1986-01-01

    The Dean and Stark distillation is an appropriate method for the determination of water in coal tar, bitumen and petroleum-like products. This article shows, however, that a direct application of the Dean and Stark method for the determination of water in biomass-derived liquid fuels results in incorrect estimates. Inaccuracies are due to the presence of soluble organics in the aqueous phase, which apparently form azeotropic mixtures with water and xylene and which condense and are trapped as distillate in the graduated cylinder. Instead, a Karl Fischer determination of water is recommended in the case of biomass-derived liquid fuels.

  18. Order parameter defining liquid-liquid transition in water

    NASA Astrophysics Data System (ADS)

    Grigera, J. Raul; Chara, Osvaldo; McCarthy, Andres

    2011-03-01

    Water presents both open tetrahedral and compact hexagonal structures. Although several order parameters have been proposed to quantify this, all of them are only applicable to data produced by simulation. We present an order parameter (Pr) that is calculated from the radial distribution function g (r) , also available from experiment. We hereby extract the tetrahedral and hexagonal components from the g (r) , each one reconstructed as the sum of a Freundlich distribution for the first peak, two subsequent Gaussian distributions, and a sigmoidal to account for the rest. The order parameter can be calculated from the relative contribution of tetrahedral over hexagonal contribution. We obtained the Pr for SPC/E water model from molecular dynamics simulations of water at different pressures and temperatures. At 300K, the pressure in which both, tetrahedral and hexagonal contributions become equal (Pr = 0), a structural crossover is found in the vicinity of 2kbar, close to the pressure at which the `'anomalous'' behavior manifests. Having computed Pr for this wide range of pressure and temperature we then calculate the HDL spinodal, the coexistence line, the second critical point, and the Widom line. Supported by CONICET, UNLP, and CIC Prov.BsAs.

  19. Onset of ice VII phase during ps laser pulse propagation through liquid water

    NASA Astrophysics Data System (ADS)

    Paturi, Prem Kiran; Vaddapally, Rakesh Kumar; Acrhem Team

    2015-06-01

    Water dominantly present in liquid state on earth gets transformed to crystalline polymorphs under different dynamic loading conditions. Out of 15 different crystalline phases discovered till date, ice VII is observed to be stable over wide pressure (2-63 GPa) and temperature (>273 K) ranges. We present the onset of ice VII phase at low threshold of 2 mJ/pulse during 30 ps (532 nm, 10 Hz) laser pulse induced shock propagating through liquid water. Role of input pulse energy on the evolution of Stoke's and anti-Stoke's Raman shift of the dominant A1g mode of ice VII, filamentation, free-electrons, plasma shielding is presented. The H-bond network rearrangement, electron ion energy transfer time coinciding with the excitation pulse duration supported by the filamentation and plasma shielding of the ps laser pulses reduced the threshold of ice VII structure formation. Filamentation and the plasma shielding have shown the localized creation and sustenance of ice VII structure in liquid water over 3 mm length and 50 μm area of cross-section. The work is supported by Defence Research and Developement Organization, India through Grants-in-Aid Program.

  20. Ice-Crystal Fallstreaks from Supercooled Liquid Water Parent Clouds

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; O'C. Starr, David; Welton, Ellsworth J.; Spinhirne, James D.; Ferrare, Richard A.

    2003-01-01

    On 31 December 2001, ice-crystal fallstreaks (e.g., cirrus uncinus, or colloquially "Mare's Tails") from supercooled liquid water parent clouds were observed by ground-based lidars pointed vertically from the Atmospheric Radiation Measurement Southern Great Plains (SGP) facility near Lamont, Oklahoma. The incidence of liquid phase cloud with apparent ice-phase precipitation is investigated. Scenarios for mixed-phase particle nucleation, and fallstreak formation and sustenance are discussed. The observations are unique in the context of the historical reverence given to the commonly observed c h s uncinus fallstreak (wholly ice) versus this seemingly contradictory coincidence of liquid water begetting ice-crystal streaks.

  1. Process for blending coal with water immiscible liquid

    DOEpatents

    Heavin, Leonard J.; King, Edward E.; Milliron, Dennis L.

    1982-10-26

    A continuous process for blending coal with a water immiscible liquid produces a uniform, pumpable slurry. Pulverized raw feed coal and preferably a coal derived, water immiscible liquid are continuously fed to a blending zone (12 and 18) in which coal particles and liquid are intimately admixed and advanced in substantially plug flow to form a first slurry. The first slurry is withdrawn from the blending zone (12 and 18) and fed to a mixing zone (24) where it is mixed with a hot slurry to form the pumpable slurry. A portion of the pumpable slurry is continuously recycled to the blending zone (12 and 18) for mixing with the feed coal.

  2. Liquid Water in the Extremely Shallow Martian Subsurface

    NASA Technical Reports Server (NTRS)

    Pavlov, A.; Shivak, J. N.

    2012-01-01

    Availability of liquid water is one of the major constraints for the potential Martian biosphere. Although liquid water is unstable on the surface of Mars due to low atmospheric pressures, it has been suggested that liquid films of water could be present in the Martian soil. Here we explored a possibility of the liquid water formation in the extremely shallow (1-3 cm) subsurface layer under low atmospheric pressures (0.1-10 mbar) and low ("Martian") surface temperatures (approx.-50 C-0 C). We used a new Goddard Martian simulation chamber to demonstrate that even in the clean frozen soil with temperatures as low as -25C the amount of mobile water can reach several percents. We also showed that during brief periods of simulated daylight warming the shallow subsurface ice sublimates, the water vapor diffuses through porous surface layer of soil temporarily producing supersaturated conditions in the soil, which leads to the formation of additional liquid water. Our results suggest that despite cold temperatures and low atmospheric pressures, Martian soil just several cm below the surface can be habitable.

  3. Liquid effluent study: Ground water characterization data

    SciTech Connect

    Not Available

    1990-08-01

    This report is a support document to the Liquid Effluent Study Final Project Report (WHC 1990c). The focus is on sampling and analysis rationale, quality assurance (QA), data validation, and sampling conditions for the groundwater quality assessment. Interpretation of the groundwater data is provided in the final project report. 20 refs., 5 figs., 2 tabs.

  4. New Isotopic Water Analyzer for Hydrological Measurements of Both Liquid Water and Water Vapor

    NASA Astrophysics Data System (ADS)

    Owano, T.; Gupta, M.; Berman, E.; Baer, D.

    2012-04-01

    Measurements of the stable isotope ratios of liquid water allow determination of water flowpaths, residence times in catchments, and groundwater migration. Previously, discrete water samples have been collected and transported to an IRMS lab for isotope characterization. Due to the expense and labor associated with such sampling, isotope studies have thus been generally limited in scope and in temporal resolution. We report on the recent development of the first Isotopic Water Analyzer that simultaneously quantifies δ2H, δ17O and δ18O in liquid water or in water vapor from different natural water sources (e.g., rain, snow, streams and groundwater). In High-Throughput mode, the IWA can report measurements at the unprecedented rate of over 800 injections per day, which yields more than 140 total unknown and reference samples per day (still with 6 injections per measurement). This fast time response provides isotope hydrologists with the capability to study dynamic changes in δ values quickly (minutes) and over long time scales (weeks, months), thus enabling studies of mixing dynamics in snowmelt, canopy throughfall, stream mixing, and allows for individual precipitation events to be independently studied. In addition, the same IWA can also record fast measurements of isotopic water vapor (δ2H, δ17O, δ18O) in real time (2 Hz data rate or faster) over a range of mole fractions greater than 60000 ppm H2O in air. Changing between operational modes requires a software command, to enable the user to switch from measuring liquid water to measuring water vapor, or vice versa. The new IWA, which uses LGR's patented Off-axis ICOS technology, incorporates proprietary internal thermal control for stable measurements with essentially zero drift despite changes in ambient temperature (over the entire range from 0-45 degrees C). Measurements from recent field studies using the IWA will be presented.

  5. Rainfall estimation from liquid water content and precipitable water content data over land, ocean and plateau

    NASA Astrophysics Data System (ADS)

    Chakraborty, S.; Adhikari, A.; Maitra, A.

    2016-01-01

    A simplistic approach has been proposed to estimate annual rainfall amount from cloud liquid water content and precipitable water content utilizing the data pertaining to the period of 1997-2006. The study involves seven land locations over India, seven stations over plateau and seven locations over the Indian Ocean. The wavelet analyses exhibit prominent annual peaks in the global spectra of rainfall, cloud liquid water content and precipitable water content. Power-law relationships are found to exist between the global wavelet peaks of precipitation and those of both the parameters, namely, cloud liquid water content and precipitable water content. Again, a linear relationship exists between global wavelet peaks of rainfall amount and total rainfall amount. The rainfall estimations utilizing cloud liquid water content data exhibit better matching with the measured values than those utilizing precipitable water content data.

  6. Metastable liquid-liquid phase separation and criticality in water-like models

    NASA Astrophysics Data System (ADS)

    Singh, Rakesh; Biddle, John; Debenedetti, Pablo; Anisimov, Mikhail

    Water shows intriguing thermodynamic and dynamic anomalies in the supercooled liquid state. A possible explanation of the origin of these anomalies lies in the existence of a metastable first order liquid-liquid phase transition (LLPT) between two (high and low density) forms of liquid water. Unambiguous experimental proof of existence of LLPT in bulk supercooled water is so far hampered by ultra-fast ice crystallization. Computer simulations of water models are therefore crucial for exploring the possibility of LLPT in deeply supercooled water. We present computer simulation results that elucidate the possibility of a metastable LLPT in one of the most accurate atomistic models of water, TIP4P/2005. To describe the computed properties, we have applied two-state thermodynamics, viewing water as a non-ideal mixture of two inter-convertible states. The thermodynamic behavior of the model in the one-phase region suggests the existence of energy-driven LLPT. We compare the behavior of TIP4P/2005 with other popular water models, and with real water, all of which are well-described by two-state thermodynamics. Additionally, we also elucidate the relation between the phenomenological order parameter of the two-state thermodynamics and the microscopic nature of the low-density structure.

  7. Liquid and Glassy Water: Two Materials of Interdisciplinary Interest

    NASA Astrophysics Data System (ADS)

    Eugene Stanley, H.

    We can superheat water above its boiling temperature and supercool it below its freezing temperature, down to approximately — 40°C, below which water inevitably crystallizes. In this deeply supercooled region, strange things happen: response functions and transport functions appear as if they might diverge to infinity at a temperature of about-45 °C. These experiments were pioneered by Angell and co-workers over the past 30 years [1-4]. Down in the glassy region of water, additional strange things happen, e.g., there is not just one glassy phase [1]. Rather, just as there is more than one polymorph of crystalline water, so also there appears to be more than one polyamorph of glassy water. The first clear indication of this was a discovery of Mishima in 1985: at low pressure there is one form, called low-density amorphous (LDA) ice [5], while at high pressure Mishima discovered a new form, called highdensity amorphous (HDA) ice [6]. The volume discontinuity separating these two phases is comparable to the volume discontinuity separating low-density and high-density polymorphs of crystalline ice, 25-35 percent [7, 8].

  8. The putative liquid-liquid transition is a liquid-solid transition in atomistic models of water. II

    SciTech Connect

    Limmer, David T.; Chandler, David

    2013-06-07

    This paper extends our earlier studies of free energy functions of density and crystalline order parameters for models of supercooled water, which allows us to examine the possibility of two distinct metastable liquid phases [D. T. Limmer and D. Chandler, J. Chem. Phys.135, 134503 (2011) and preprint http://arxiv.org/abs/arXiv:1107.0337 (2011)]. Low-temperature reversible free energy surfaces of several different atomistic models are computed: mW water, TIP4P/2005 water, Stillinger-Weber silicon, and ST2 water, the last of these comparing three different treatments of long-ranged forces. In each case, we show that there is one stable or metastable liquid phase, and there is an ice-like crystal phase. The time scales for crystallization in these systems far exceed those of structural relaxation in the supercooled metastable liquid. We show how this wide separation in time scales produces an illusion of a low-temperature liquid-liquid transition. The phenomenon suggesting metastability of two distinct liquid phases is actually coarsening of the ordered ice-like phase, which we elucidate using both analytical theory and computer simulation. For the latter, we describe robust methods for computing reversible free energy surfaces, and we consider effects of electrostatic boundary conditions. We show that sensible alterations of models and boundary conditions produce no qualitative changes in low-temperature phase behaviors of these systems, only marginal changes in equations of state. On the other hand, we show that altering sampling time scales can produce large and qualitative non-equilibrium effects. Recent reports of evidence of a liquid-liquid critical point in computer simulations of supercooled water are considered in this light.

  9. The putative liquid-liquid transition is a liquid-solid transition in atomistic models of water. II.

    PubMed

    Limmer, David T; Chandler, David

    2013-06-01

    This paper extends our earlier studies of free energy functions of density and crystalline order parameters for models of supercooled water, which allows us to examine the possibility of two distinct metastable liquid phases [D. T. Limmer and D. Chandler, J. Chem. Phys. 135, 134503 (2011) and preprint arXiv:1107.0337 (2011)]. Low-temperature reversible free energy surfaces of several different atomistic models are computed: mW water, TIP4P/2005 water, Stillinger-Weber silicon, and ST2 water, the last of these comparing three different treatments of long-ranged forces. In each case, we show that there is one stable or metastable liquid phase, and there is an ice-like crystal phase. The time scales for crystallization in these systems far exceed those of structural relaxation in the supercooled metastable liquid. We show how this wide separation in time scales produces an illusion of a low-temperature liquid-liquid transition. The phenomenon suggesting metastability of two distinct liquid phases is actually coarsening of the ordered ice-like phase, which we elucidate using both analytical theory and computer simulation. For the latter, we describe robust methods for computing reversible free energy surfaces, and we consider effects of electrostatic boundary conditions. We show that sensible alterations of models and boundary conditions produce no qualitative changes in low-temperature phase behaviors of these systems, only marginal changes in equations of state. On the other hand, we show that altering sampling time scales can produce large and qualitative non-equilibrium effects. Recent reports of evidence of a liquid-liquid critical point in computer simulations of supercooled water are considered in this light. PMID:23758385

  10. Liquid water transport mechanism in the gas diffusion layer

    NASA Astrophysics Data System (ADS)

    Zhou, P.; Wu, C. W.

    We developed an equivalent capillary model of a microscale fiber-fence structure to study the microscale evolution and transport of liquid in a porous media and to reveal the basic principles of water transport in gas diffusion layer (GDL). Analytical solutions using the model show that a positive hydraulic pressure is needed to drive the liquid water to penetrate through the porous GDL even consisting of the hydrophilic fibers. Several possible contributions for the water configuration, such as capillary pressure, gravity, vapor condensation, wettability and microstructures of the GDL, are discussed using the lattice Boltzmann method (LBM). It is found that the distribution manners of the fibers and the spatial mixed-wettability in the GDL also play an important role in the transport of liquid water.

  11. Searching for liquid water in Europa by using surface observatories.

    PubMed

    Khurana, Krishan K; Kivelson, Margaret G; Russell, Christopher T

    2002-01-01

    Liquid water, as far as we know, is an indispensable ingredient of life. Therefore, locating reservoirs of liquid water in extraterrestrial bodies is a necessary prerequisite to searching for life. Recent geological and geophysical observations from the Galileo spacecraft, though not unambiguous, hint at the possibility of a subsurface ocean in the Jovian moon Europa. After summarizing present evidence for liquid water in Europa, we show that electromagnetic and seismic observations made from as few as two surface observatories comprising a magnetometer and a seismometer offer the best hope of unambiguous characterization of the three-dimensional structure of the ocean and the deeper interior of this icy moon. The observatories would also help us infer the composition of the icy crust and the ocean water. PMID:12449858

  12. Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water

    NASA Astrophysics Data System (ADS)

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-08-01

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  13. Behavior of supercooled aqueous solutions stemming from hidden liquid-liquid transition in water.

    PubMed

    Biddle, John W; Holten, Vincent; Anisimov, Mikhail A

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases. PMID:25149798

  14. Structure and Depletion at Fluorocarbon and Hydrocarbon/Water Liquid/Liquid Interfaces

    SciTech Connect

    Kashimoto,K.; Yoon, J.; Hou, B.; Chen, C.; Lin, B.; Aratono, M.; Takiue, T.; Schlossman, M.

    2008-01-01

    The results of x-ray reflectivity studies of two oil/water (liquid/liquid) interfaces are inconsistent with recent predictions of the presence of a vaporlike depletion region at hydrophobic/aqueous interfaces. One of the oils, perfluorohexane, is a fluorocarbon whose superhydrophobic interface with water provides a stringent test for the presence of a depletion layer. The other oil, heptane, is a hydrocarbon and, therefore, is more relevant to the study of biomolecular hydrophobicity. These results are consistent with the subangstrom proximity of water to soft hydrophobic materials.

  15. A Mechanism for Recent Production of Liquid Water on Mars

    NASA Technical Reports Server (NTRS)

    Hecht, M. H.; Bridges, N. T.

    2003-01-01

    Though Mars is a cold, dry planet, with respect to the thermal stability of liquid water at low altitudes it is not terribly different from comparably cold places on Earth. In dry air such water would evaporate faster on Mars, at a rate comparable to a 60 C hot spring on Earth, but the heat loss associated with that evaporation would be mitigated by the poor thermal convection in the thin Martian air. Even at higher altitudes where the atmospheric pressure does not reach the triple point of water, liquid water might theoretically exist in a low-vapor pressure form such as wet soil, in a briny solution, or simply under a layer of dust or snow. The theoretical stability of liquid water does not suggest its occurrence, either on Mars or in Antarctica. In fact, global models have suggested that locations capable of providing sufficient heat for melting are, precisely for that reason, too dry for water to be present. However, the temperature of irregular local structures such as trenches or craters can be markedly warmer than those of the uniform surfaces of global models. The work described here suggests a plausible scenario in which seasonal liquid water might be produced locally, in sheltered locations, through a process of condensation, cold-trapping, buffering, and melting. While the amounts produced in the present climate would be small, copious amounts of meltwater may have been produced at other phases of the orbital cycle, as recently as 20,000 years ago.

  16. The puzzling unsolved mysteries of liquid water: Some recent progress

    NASA Astrophysics Data System (ADS)

    Stanley, H. E.; Kumar, P.; Xu, L.; Yan, Z.; Mazza, M. G.; Buldyrev, S. V.; Chen, S.-H.; Mallamace, F.

    2007-12-01

    Water is perhaps the most ubiquitous, and the most essential, of any molecule on earth. Indeed, it defies the imagination of even the most creative science fiction writer to picture what life would be like without water. Despite decades of research, however, water's puzzling properties are not understood and 63 anomalies that distinguish water from other liquids remain unsolved. We introduce some of these unsolved mysteries, and demonstrate recent progress in solving them. We present evidence from experiments and computer simulations supporting the hypothesis that water displays a special transition point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell). The general idea is that when the liquid is near this “tipping point,” it suddenly separates into two distinct liquid phases. This concept of a new critical point is finding application to other liquids as well as water, such as silicon and silica. We also discuss related puzzles, such as the mysterious behavior of water near a protein.

  17. Experimental evidence for a liquid-liquid crossover in deeply cooled confined water.

    PubMed

    Cupane, Antonio; Fomina, Margarita; Piazza, Irina; Peters, Judith; Schirò, Giorgio

    2014-11-21

    In this work we investigate, by means of elastic neutron scattering, the pressure dependence of mean square displacements (MSD) of hydrogen atoms of deeply cooled water confined in the pores of a three-dimensional disordered SiO2 xerogel; experiments have been performed at 250 and 210 K from atmospheric pressure to 1200 bar. The "pressure anomaly" of supercooled water (i.e., a mean square displacement increase with increasing pressure) is observed in our sample at both temperatures; however, contrary to previous simulation results and to the experimental trend observed in bulk water, the pressure effect is smaller at lower (210 K) than at higher (250 K) temperature. Elastic neutron scattering results are complemented by differential scanning calorimetry data that put in evidence, besides the glass transition at about 170 K, a first-order-like endothermic transition occurring at about 230 K that, in view of the neutron scattering results, can be attributed to a liquid-liquid crossover. Our results give experimental evidence for the presence, in deeply cooled confined water, of a crossover occurring at about 230 K (at ambient pressure) from a liquid phase predominant at 210 K to another liquid phase predominant at 250 K; therefore, they are fully consistent with the liquid-liquid transition hypothesis. PMID:25479506

  18. Fluorescent liquid pyrene derivative-in-water microemulsions.

    PubMed

    Hollamby, M J; Danks, A E; Schnepp, Z; Rogers, S E; Hart, S R; Nakanishi, T

    2016-05-31

    A fluorescent liquid pyrene derivative with a high fluorescence quantum yield (65%) in the bulk state is reported. With this as the sole oil phase, stable luminescent oil-in-water microemulsions have been prepared. Increasing the loading of liquid pyrene swells the droplets, as detected by small-angle neutron scattering. These larger droplets have a greater proportion of pyrene excimer emission contribution in their photoluminescence spectra, which leads to a red shift in the chromaticity of the emission. PMID:27194647

  19. Surface potential of the water liquid-vapor interface

    NASA Technical Reports Server (NTRS)

    Wilson, Michael A.; Pohorille, Andrew; Pratt, Lawrence R.

    1988-01-01

    An analysis of an extended molecular dynamics calculation of the surface potential (SP) of the water liquid-vapor interface is presented. The SP predicted by the TIP4P model is -(130 + or - 50) mV. This value is of reasonable magnitude but of opposite sign to the expectations based on laboratory experiments. The electrostatic potential shows a nonmonotonic variation with depth into the liquid.

  20. Metastability of Liquid Water on Mars

    NASA Technical Reports Server (NTRS)

    Hecht, M. H.

    2001-01-01

    This talk reviews reasonable spatial and temporal scales for melting and flowing of water on Mars, and relates them to plausible martian conditions. Additional information is contained in the original extended abstract.

  1. Bond orientational order in liquids: Towards a unified description of water-like anomalies, liquid-liquid transition, glass transition, and crystallization: Bond orientational order in liquids.

    PubMed

    Tanaka, Hajime

    2012-10-01

    There are at least three fundamental states of matter, depending upon temperature and pressure: gas, liquid, and solid (crystal). These states are separated by first-order phase transitions between them. In both gas and liquid phases a complete translational and rotational symmetry exist, whereas in a solid phase both symmetries are broken. In intermediate phases between liquid and solid, which include liquid crystal and plastic crystal phases, only one of the two symmetries is preserved. Among the fundamental states of matter, the liquid state is the most poorly understood. We argue that it is crucial for a better understanding of liquids to recognize that a liquid generally has the tendency to have a local structural order and its presence is intrinsic and universal to any liquid. Such structural ordering is a consequence of many-body correlations, more specifically, bond angle correlations, which we believe are crucial for the description of the liquid state. We show that this physical picture may naturally explain difficult unsolved problems associated with the liquid state, such as anomalies of water-type liquids (water, Si, Ge, ...), liquid-liquid transition, liquid-glass transition, crystallization and quasicrystal formation, in a unified manner. In other words, we need a new order parameter representing a low local free-energy configuration, which is a bond orientational order parameter in many cases, in addition to a density order parameter for the physical description of these phenomena. Here we review our two-order-parameter model of liquid and consider how transient local structural ordering is linked to all of the above-mentioned phenomena. The relationship between these phenomena is also discussed. PMID:23104614

  2. Photochemical water oxidation by crystalline polymorphs of manganese oxides: structural requirements for catalysis.

    PubMed

    Robinson, David M; Go, Yong Bok; Mui, Michelle; Gardner, Graeme; Zhang, Zhijuan; Mastrogiovanni, Daniel; Garfunkel, Eric; Li, Jing; Greenblatt, Martha; Dismukes, G Charles

    2013-03-01

    Manganese oxides occur naturally as minerals in at least 30 different crystal structures, providing a rigorous test system to explore the significance of atomic positions on the catalytic efficiency of water oxidation. In this study, we chose to systematically compare eight synthetic oxide structures containing Mn(III) and Mn(IV) only, with particular emphasis on the five known structural polymorphs of MnO2. We have adapted literature synthesis methods to obtain pure polymorphs and validated their homogeneity and crystallinity by powder X-ray diffraction and both transmission and scanning electron microscopies. Measurement of water oxidation rate by oxygen evolution in aqueous solution was conducted with dispersed nanoparticulate manganese oxides and a standard ruthenium dye photo-oxidant system. No Ru was absorbed on the catalyst surface as observed by XPS and EDX. The post reaction atomic structure was completely preserved with no amorphization, as observed by HRTEM. Catalytic activities, normalized to surface area (BET), decrease in the series Mn2O3 > Mn3O4 ≫ λ-MnO2, where the latter is derived from spinel LiMn2O4 following partial Li(+) removal. No catalytic activity is observed from LiMn2O4 and four of the MnO2 polymorphs, in contrast to some literature reports with polydispersed manganese oxides and electro-deposited films. Catalytic activity within the eight examined Mn oxides was found exclusively for (distorted) cubic phases, Mn2O3 (bixbyite), Mn3O4 (hausmannite), and λ-MnO2 (spinel), all containing Mn(III) possessing longer Mn-O bonds between edge-sharing MnO6 octahedra. Electronically degenerate Mn(III) has antibonding electronic configuration e(g)(1) which imparts lattice distortions due to the Jahn-Teller effect that are hypothesized to contribute to structural flexibility important for catalytic turnover in water oxidation at the surface. PMID:23391134

  3. Thermodynamic determination of fragility in liquids and a fragile-to-strong liquid transition in water

    NASA Astrophysics Data System (ADS)

    Ito, Kaori; Moynihan, Cornelius T.; Angell, C. Austen

    1999-04-01

    If crystallization can be avoided when a liquid is cooled, it will typically form a glass. Near the glass transition temperature the viscosity increases continuously but rapidly with cooling. As the glass forms, the molecular relaxation time increases with an Arrhenius-like (simple activated) form in some liquids, but shows highly non-Arrhenius behaviour in others. The former are said to be `strong' liquids, and the latter `fragile',. Here we show that the fragility of a liquid can be determined from purely thermodynamic data (as opposed to measurements of kinetics) near and below the melting point. We find that for most liquids the fragilities estimated this way are consistent with those obtained by previous methods and by a new method (ref. 3 and K.I., C.A.A. and C.T.M., unpublished data) at temperatures near the glass transition. But water is an exception. The thermodynamic method indicates that near its melting point it is the most fragile of all liquids studied, whereas the kinetic approach indicates that near the glass transition it is the least fragile. We propose that this discrepancy can be explained by a fragile-to-strong transition in supercooled water near 228K, corresponding to a change in the liquid's structure at this point.

  4. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    PubMed Central

    Yu, Tang-Qing; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Vanden-Eijnden, Eric; Tuckerman, Mark

    2014-01-01

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency. PMID:24907992

  5. Order-parameter-aided temperature-accelerated sampling for the exploration of crystal polymorphism and solid-liquid phase transitions

    SciTech Connect

    Yu, Tang-Qing Vanden-Eijnden, Eric; Chen, Pei-Yang; Chen, Ming; Samanta, Amit; Tuckerman, Mark

    2014-06-07

    The problem of predicting polymorphism in atomic and molecular crystals constitutes a significant challenge both experimentally and theoretically. From the theoretical viewpoint, polymorphism prediction falls into the general class of problems characterized by an underlying rough energy landscape, and consequently, free energy based enhanced sampling approaches can be brought to bear on the problem. In this paper, we build on a scheme previously introduced by two of the authors in which the lengths and angles of the supercell are targeted for enhanced sampling via temperature accelerated adiabatic free energy dynamics [T. Q. Yu and M. E. Tuckerman, Phys. Rev. Lett. 107, 015701 (2011)]. Here, that framework is expanded to include general order parameters that distinguish different crystalline arrangements as target collective variables for enhanced sampling. The resulting free energy surface, being of quite high dimension, is nontrivial to reconstruct, and we discuss one particular strategy for performing the free energy analysis. The method is applied to the study of polymorphism in xenon crystals at high pressure and temperature using the Steinhardt order parameters without and with the supercell included in the set of collective variables. The expected fcc and bcc structures are obtained, and when the supercell parameters are included as collective variables, we also find several new structures, including fcc states with hcp stacking faults. We also apply the new method to the solid-liquid phase transition in copper at 1300 K using the same Steinhardt order parameters. Our method is able to melt and refreeze the system repeatedly, and the free energy profile can be obtained with high efficiency.

  6. Solid-liquid critical behavior of water in nanopores.

    PubMed

    Mochizuki, Kenji; Koga, Kenichiro

    2015-07-01

    Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid-liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature-pressure-diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid-liquid critical phenomena of nanoconfined water. Solid-liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid-liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line. PMID:26100904

  7. Solid−liquid critical behavior of water in nanopores

    PubMed Central

    Mochizuki, Kenji; Koga, Kenichiro

    2015-01-01

    Nanoconfined liquid water can transform into low-dimensional ices whose crystalline structures are dissimilar to any bulk ices and whose melting point may significantly rise with reducing the pore size, as revealed by computer simulation and confirmed by experiment. One of the intriguing, and as yet unresolved, questions concerns the observation that the liquid water may transform into a low-dimensional ice either via a first-order phase change or without any discontinuity in thermodynamic and dynamic properties, which suggests the existence of solid−liquid critical points in this class of nanoconfined systems. Here we explore the phase behavior of a model of water in carbon nanotubes in the temperature−pressure−diameter space by molecular dynamics simulation and provide unambiguous evidence to support solid−liquid critical phenomena of nanoconfined water. Solid−liquid first-order phase boundaries are determined by tracing spontaneous phase separation at various temperatures. All of the boundaries eventually cease to exist at the critical points and there appear loci of response function maxima, or the Widom lines, extending to the supercritical region. The finite-size scaling analysis of the density distribution supports the presence of both first-order and continuous phase changes between solid and liquid. At around the Widom line, there are microscopic domains of two phases, and continuous solid−liquid phase changes occur in such a way that the domains of one phase grow and those of the other evanesce as the thermodynamic state departs from the Widom line. PMID:26100904

  8. On the Stability of Liquid Water on Present Day Mars

    NASA Technical Reports Server (NTRS)

    Haberle, Robert M.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The mean annual surface pressure and temperature on present day Mars do not allow for the long term stability of liquid water on the surface. However, theoretical arguments have been advanced that suggest liquid water could form in transient events even though it would not be in equilibrium with the environment. Using a Mars General Circulation Model, we calculate where and for how long the surface pressure and surface temperature meet the minimum requirements for this metastability of liquid water. These requirements are that the pressure and temperature must be above the triple point of water, but below its boiling point. We find that there are five regions on Mars where these requirements are periodically satisfied: in the near equatorial regions of Amazonis, Arabia, and Elysium, and in the Hellas and Argyre impact basins. Whether liquid water ever forms in these regions depends on the availability of ice and heat, and on the evaporation rate. The latter is poorly understood for low pressure CO2 environments, but is likely to be so high that melting occurs rarely, if at all. However, in the relatively recent past, surface pressures may have been higher than they are today perhaps by as much as a factor of 2 or 3. Under these circumstances melting would have been easier to achieve. We plan to undertake laboratory experiments to better understand the potential for melting in low pressure environments.

  9. Resurfacing of Ganymede by Liquid-Water Volcanism

    NASA Technical Reports Server (NTRS)

    Showman, A. P.; Mosqueira, I.; Head, J. W., III

    2004-01-01

    A long-popular model for producing Ganymede s bright terrain involves flooding of low-lying graben with liquid water, slush, or warm, soft ice. The model suffers from major problems, however, including the absence of obvious near-surface heat sources, the negative buoyancy of liquid water, and the lack of a mechanism for confining the flows to graben floors. We show that topography - such as a global set of graben - causes subsurface (a hydrostatic) pressure gradients that can "suck" subsurface liquid water upward onto the floors of topographic lows (graben). As the low areas become full, the pressure gradients disappear and the resurfacing ceases. This provides an explanation for the observed straight dark-bright terrain boundaries: water cannot overflow the graben, so surfacing rarely embays craters and other rough topography. Subsurface liquid water must exist for the scenario to exist, of course, and is plausibly provided by tidal heating during an ancient orbital resonance. This abstract is a summary of Showman et al. recently submitted to Icarus.

  10. Entropy of Liquid Water from Ab Initio Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Spanu, Leonardo; Zhang, Cui; Galli, Giulia

    2012-02-01

    The debate on the structural properties of water has been mostly based on the calculation of pair correlation functions. However, the simulation of thermodynamic and spectroscopic quantities may be of great relevance for the characterization of liquid water properties. We have computed the entropy of liquid water using a two-phase thermodynamic model and trajectories generated by ab initio molecular dynamics simulations [1]. In an attempt to better understand the performance of several density functionals in simulating liquid water, we have performed ab initio molecular dynamics using semilocal, hybrid [2] and van der Waals density functionals [3]. We show that in all cases, at the experimental equilibrium density and at temperatures in the vicinity of 300 K, the computed entropies are underestimated, with respect to experiment, and the liquid exhibits a degree of tetrahedral order higher than in experiments. We also discuss computational strategies to simulate spectroscopic properties of water, including infrared and Raman spectra.[4pt] [1] C.Zhang, L.Spanu and G.Galli, J.Phys.Chem. B 2011 (in press)[0pt] [2] C.Zhang, D.Donadio, F.Gygi and G.Galli, J. Chem. Theory Comput. 7, 1443 (2011)[0pt] [3] C.Zhang, J.Wu, G.Galli and F.Gygi, J. Chem. Theory Comput. 7, 3061 (2011)

  11. Comparison of the optical reflectivity of a shock front in liquid water and in liquid nitromethane

    NASA Astrophysics Data System (ADS)

    Harris, P.; Presles, H. N.

    1982-11-01

    Shock front optical reflectivity data for liquid water at 5.8 kbar and for liquid nitromethane at 6.0 kbar are analyzed with a reflectivity theory containing reflection within the shock front. Comparison of the analyses for water and for nitromethane leads to the conclusion that additional physics is necessary to explain the nitromethane data. It is suggested that the experimental-theoretical discrepancy for nitromethane is optical-path-length dependent, and that discrepancy is possibly due to thermal fluctuations related to explosive chemistry.

  12. Economics of liquid hydrogen from water electrolysis

    NASA Technical Reports Server (NTRS)

    Lin, F. N.; Moore, W. I.; Walker, S. W.

    1985-01-01

    An economical model for preliminary analysis of LH2 cost from water electrolysis is presented. The model is based on data from vendors and open literature, and is suitable for computer analysis of different scenarios for 'directional' purposes. Cost data associated with a production rate of 10,886 kg/day are presented. With minimum modification, the model can also be used to predict LH2 cost from any electrolyzer once the electrolyzer's cost data are available.

  13. New Isotopic Water Analyzer for Hydrological Measurements of both Liquid Water and Water Vapor

    NASA Astrophysics Data System (ADS)

    Owano, T. G.; Gupta, M.; Dong, F.; Baer, D. S.

    2011-12-01

    Measurements of the stable isotope ratios of liquid water (δ2H and δ18O) allow determination of water flowpaths, residence times in catchments, and groundwater migration. In the past, discrete water samples have been collected and transported to an IRMS lab for isotope characterization. Due to the expense and labor associated with such sampling, isotope studies have thus been generally limited in scope and in temporal resolution. We report on the recent development of a new field-portable Isotopic Water Analyzer (IWA-35EP) that accurately quantifies δ2H and δ18O of different natural water sources (e.g., rain, snow, streams and groundwater) at the unprecedented rate of 1080 injections per day, which yields 180 total unknown and reference samples per day (150 unknown samples per day), or 1 measurement of an unknown sample in less than 10 minutes (with 6 injections per measurement). This fast time response provides isotope hydrologists with the capability to study dynamic changes in δ values quickly (minutes) and over long time scales (weeks, months), thus enabling studies of mixing dynamics in snowmelt, canopy throughfall, stream mixing, and allows for individual precipitation events to be independently studied. In addition, the same IWA can also record fast measurements of isotopic water vapor (δ18O and δ2H) in real time (2 Hz data rate or faster) over a range of mole fractions greater than 60000 ppm H2O in air. Changing between operational modes requires a software command, to enable the user to switch from measuring liquid water to measuring water vapor, or vice versa. The new IWA, which uses LGR's patented Off-axis ICOS technology, incorporates proprietary internal thermal control for stable measurements with essentially zero drift. Measurements from recent field studies using the IWA will be presented.

  14. Coherent structures in liquid water close to hydrophilic surfaces

    NASA Astrophysics Data System (ADS)

    Del Giudice, Emilio; Tedeschi, Alberto; Vitiello, Giuseppe; Voeikov, Vladimir

    2013-06-01

    Quantum Electrodynamics (QED) predicts the occurrence of a number of coherent dynamical phenomena in liquid water. In the present paper we focus our attention on the joint coherent oscillation of the almost free electrons produced by the coherent oscillation of the electron clouds of water molecules, which has been described in previous publications, and of the negative electric charges lying on the solid surfaces wet by water. This joint coherent oscillation gives rise to a number of phenomenological consequences which are found to exist in the physical reality and coincide with the layers of Exclusion Zone (EZ) water experimentally observed close to hydrophilic surfaces.

  15. Satellite Remote Sensing of the Liquid Water Sensitivity in Water Clouds

    NASA Technical Reports Server (NTRS)

    Han, Qing-Yuan; Rossow, William B.; Welch, Ronald; Zeng, Jane; Jansen, James E. (Technical Monitor)

    2001-01-01

    In estimation of the aerosol indirect effect, cloud liquid water path is considered either constant (Twomey effect) or increasing with enhanced droplet number concentrations (drizzle-suppression effect, or Albrecht effect) if cloud microphysics is the prevailing mechanism during the aerosol-cloud interactions. On the other hand, if cloud thermodynamics and dynamics are considered, the cloud liquid water path may be decreased with increasing droplet number concentration, which is predicted by model calculations and observed in ship-track and urban influence studies. This study is to examine the different responses of cloud liquid water path to changes of cloud droplet number concentration. Satellite data (January, April, July and October 1987) are used to retrieve the cloud liquid water sensitivity, defined as the changes of liquid water path versus changes of column droplet number concentrations. The results of a global survey reveal that 1) in at least one third of the cases the cloud liquid water sensitivity is negative, and the regional and seasonal variations of the negative liquid water sensitivity are consistent with other observations; 2) cloud droplet sizes are always inversely proportional to column droplet number concentrations. Our results suggest that an increase of cloud droplet number concentration leads to reduced cloud droplet size and enhanced evaporation, which weakens the coupling between water clouds and boundary layer in warm zones, decreases water supply from surface and desiccates cloud liquid water. Our results also suggest that the current evaluations of negative aerosol indirect forcing by global climate models (GCM), which are based on Twomey effect or Albrecht effect, may be overestimated.

  16. Liquid-liquid interfaces of semifluorinated alkane diblock copolymers with water, alkanes, and perfluorinated alkanes.

    SciTech Connect

    Perahia, Dvora, Dr.; Pierce, Flint; Tsige, Mesfin; Grest, Gary Stephen, Dr.

    2008-08-01

    The liquid-liquid interface between semifluorinated alkane diblock copolymers of the form F3C(CF2)n-1-(CH2)m-1CH3 and water, protonated alkanes, and perfluorinated alkanes are studied by fully atomistic molecular dynamics simulations. A modified version of the OPLS-AA (Optimized Parameter for Liquid Simulation All-Atom) force field of Jorgensen et al. has been used to study the interfacial behavior of semifluorinated diblocks. Aqueous interfaces are found to be sharp, with correspondingly large values of the interfacial tension. Due to the reduced hydrophobicity of the protonated block compared to the fluorinated block, hydrogen enhancement is observed at the interface. Water dipoles in the interfacial region are found to be oriented nearly parallel to the liquid-liquid interface. A number of protonated alkanes and perfluorinated alkanes are found to be mutually miscible with the semifluorinated diblocks. For these liquids, interdiffusion follows the expected Fickian behavior, and concentration-dependent diffusivities are determined.

  17. HNC solution for the central force model for liquid water

    NASA Astrophysics Data System (ADS)

    Thuraisingham, Ranjit A.; Friedman, Harold L.

    1983-05-01

    Beginning with the central force model for water introduced by Lemberg, Stillinger, and Rahman, the HNC approximation method has been used to calculate the atom-atom pair correlation functions of a state of liquid water. Although a stable and accurate solution to the HNC equation for the model is obtained using the Rossky-Dale algorithm, the structure and thermodynamics agree only crudely with the published molecular dynamics results for the same model and the same N, V, T state.

  18. Boiling-up of liquid nitrogen jet in water

    NASA Astrophysics Data System (ADS)

    Nakoryakov, V. E.; Tsoi, A. N.; Mezentsev, I. V.; Meleshkin, A. V.

    2014-06-01

    The hydrodynamic processes occurring at injection of cryogenic liquid into water pool were studied experimentally. Processes accompanying the phase transitions were registered. Data testify the developing pressure burst with an amplitude sufficient for possible formation of gas hydrates when methane is injected as a cryogenic fluid.

  19. Molecular dynamics simulation of liquid water: Hybrid density functionals

    SciTech Connect

    Todorova, T; Seitsonen, A; Hutter, J; Kuo, W; Mundy, C

    2005-09-12

    The structure, dynamical and electronic properties of liquid water utilizing different hybrid density functionals were tested within the plane wave framework of first principles molecular dynamics simulations. The computational approach, which employs modified functionals with short-ranged Hartree-Fock exchange, was first tested in calculations of the structural and bonding properties of the water dimer and cyclic water trimer. Liquid water simulations were performed at the state point of 350 K at the experimental density. Simulations included three different hybrid functionals, a meta functional, four gradient corrected functionals, the local density and Hartree-Fock approximation. It is found that hybrid functionals are superior in reproducing the experimental structure and dynamical properties as measured by the radial distribution function and self diffusion constant when compared to the pure density functionals. The local density and Hartree-Fock approximations show strongly over- and under-structured liquids, respectively. Hydrogen bond analysis shows that the hybrid functionals give slightly smaller averaged numbers of hydrogen bonds and similar hydrogen bond populations as pure density functionals. The average molecular dipole moments in the liquid from the three hybrid functionals are lower than from the corresponding pure density functionals.

  20. Molecular dynamics of the water liquid-vapor interface

    NASA Technical Reports Server (NTRS)

    Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

    1987-01-01

    The results of molecular dynamics calculations on the equilibrium interface between liquid water and its vapor at 325 K are presented. For the TIP4P model of water intermolecular pair potentials, the average surface dipole density points from the vapor to the liquid. The most common orientations of water molecules have the C2 nu molecular axis roughly parallel to the interface. The distributions are quite broad and therefore compatible with the intermolecular correlations characteristic of bulk liquid water. All near-neighbor pairs in the outermost interfacial layers are hydrogen bonded according to the common definition adopted here. The orientational preferences of water molecules near a free surface differ from those near rigidly planar walls which can be interpreted in terms of patterns found in hexagonal ice 1. The mean electric field in the interfacial region is parallel to the mean polarization which indicates that attention cannot be limited to dipolar charge distributions in macroscopic descriptions of the electrical properties of this interface. The value of the surface tension obtained is 132 +/- 46 dyn/cm, significantly different from the value for experimental water of 68 dyn/cm at 325 K.

  1. Adsorbed water and thin liquid films on Mars

    NASA Astrophysics Data System (ADS)

    Boxe, C. S.; Hand, K. P.; Nealson, K. H.; Yung, Y. L.; Yen, A. S.; Saiz-Lopez, A.

    2012-07-01

    At present, bulk liquid water on the surface and near-subsurface of Mars does not exist due to the scarcity of condensed- and gas-phase water, pressure and temperature constraints. Given that the nuclei of soil and ice, that is, the soil solid and ice lattice, respectively, are coated with adsorbed and/or thin liquid films of water well below 273 K and the availability of water limits biological activity, we quantify lower and upper limits for the thickness of such adsorbed/water films on the surface of the Martian regolith and for subsurface ice. These limits were calculated based on experimental and theoretical data for pure water ice and water ice containing impurities, where water ice containing impurities exhibit thin liquid film enhancements, ranging from 3 to 90. Close to the cold limit of water stability (i.e. 273 K), thin liquid film thicknesses at the surface of the Martian regolith is 0.06 nm (pure water ice) and ranges from 0.2 to 5 nm (water ice with impurities). An adsorbed water layer of 0.06 nm implies a dessicated surface as the thickness of one monolayer of water is 0.3 nm but represents 0.001-0.02% of the Martian atmospheric water vapour inventory. Taking into account the specific surface area (SSA) of surface-soil (i.e. top 1 mm of regolith and 0.06 nm adsorbed water layer), shows Martian surface-soil may contain interfacial water that represents 6-66% of the upper- and lower-limit atmospheric water vapour inventory and almost four times and 33%, the lower- and upper-limit Martian atmospheric water vapour inventory. Similarly, taking the SSA of Martian soil, the top 1 mm or regolith at 5 nm thin liquid water thickness, yields 1.10×1013 and 6.50×1013 litres of waters, respectively, 55-325 times larger than Mars' atmospheric water vapour inventory. Film thicknesses of 0.2 and 5 nm represent 2.3×104-1.5×106 litres of water, which is 6.0×10-7-4.0×10-4%, respectively, of a 10 pr μm water vapour column, and 3.0×10-6-4.0×10-4% and 6.0×10

  2. Speciation analysis of mercury in water samples using dispersive liquid-liquid microextraction combined with high-performance liquid chromatography.

    PubMed

    Gao, Zhongben; Ma, Xiaoguo

    2011-09-19

    A novel approach for preconcentration and speciation analysis of trace amount of mercury from water samples was proposed by dispersive liquid-liquid microextraction (DLLME) coupled to high performance liquid chromatography with diode array detection (HPLC-DAD). Mercury species (Hg(2+), methylmercury (MeHg(+)) and phenylmercury (PhHg(+))) were complexed with dithizone (DZ) to form hydrophobic chelates and then extracted into the fine drops of extraction solvent dispersed in the aqueous sample by dispersive solvent. After extraction, the sedimented phase was analyzed by HPLC-DAD. Some important parameters affecting the DLLME such as extraction solvent and dispersive solvent type and volume, concentration of dithizone solution, sample pH, extraction time and salt effect were investigated. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]) was found to be a suitable extractant for the chelates. Under the optimized conditions (extraction solvent: 70 μL of ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF(6)]); dispersive solvent: 0.75 mL of methanol containing dithizone (0.02%, m/v); pH: 4; extraction time: 5 min; and without salt addition), the limits of detection for Hg(2+), MeHg(+) and PhHg(+) were 0.32, 0.96 and 1.91 μg L(-1) (SN(-1)=3) respectively, and the relative standard deviation (RSD) was between 4.1 and 7.3% (n=5). Three real water samples (tap water, river water and lake water) spiked with mercury species were detected by the developed method, and the relative recoveries obtained for Hg(2+), MeHg(+) and PhHg(+) were 89.6-101.3%, 85.6-102.0% and 81.3-97.6%, respectively. PMID:21819859

  3. Self-Assembly and Orientation of Hydrogen-Bonded Oligothiophene Polymorphs at Liquid-Membrane-Liquid Interfaces

    SciTech Connect

    Tevis, Ian D; Palmer, Liam C; Herman, David J; Murray, Ian P; Stone, David A; Stupp, Samuel I

    2012-03-15

    One of the challenges in organic systems with semiconducting function is the achievement of molecular orientation over large scales. We report here on the use of self-assembly kinetics to control long-range orientation of a quarterthiophene derivative designed to combine intermolecular π-π stacking and hydrogen bonding among amide groups. Assembly of these molecules in the solution phase is prevented by the hydrogen-bond-accepting solvent tetrahydrofuran, whereas formation of H-aggregates is facilitated in toluene. Rapid evaporation of solvent in a solution of the quarterthiophene in a 2:1:1 mixture of 1,4-dioxane/tetrahydrofuran/toluene leads to self-assembly of kinetically trapped mats of bundled fibers. In great contrast, slow drying in a toluene atmosphere leads to the homogeneous nucleation and growth of ordered structures shaped as rhombohedra or hexagonal prisms depending on concentration. Furthermore, exceedingly slow delivery of toluene from a high molecular weight polymer solution into the system through a porous aluminum oxide membrane results in the growth of highly oriented hexagonal prisms perpendicular to the interface. The amide groups of the compound likely adsorb onto the polar aluminum oxide surface and direct the self-assembly pathway toward heterogeneous nucleation and growth to form hexagonal prisms. We propose that the oriented prismatic polymorph results from the synergy of surface interactions rooted in hydrogen bonding on the solid membrane and the slow kinetics of self-assembly. These observations demonstrate how self-assembly conditions can be used to guide the supramolecular energy landscape to generate vastly different structures. These fundamental principles allowed us to grow oriented prismatic assemblies on transparent indium-doped tin oxide electrodes, which are of interest in organic electronics.

  4. Anisotropic behavior of water in ferroelectric liquid crystals.

    PubMed

    Singh, G; Choudhary, A; Prakash, G Vijaya; Biradar, A M

    2010-05-01

    The outcome of water addition in ferroelectric liquid crystal (FLC) has been investigated in uniform and defect-free homogeneous and homeotropically aligned monodomain sample cells from electro-optical and dielectric spectroscopic measurements. The lagging in optical response between nonconducting (spatially variable switching) and conducting (conventional switching) portions of water added FLC sample cell has been observed by frequency-dependent electro-optical studies. The bias-dependent water related new relaxation peak near the conventional Goldstone mode relaxation process has been observed only in the homogeneous alignment and not in the homeotropic one. Further, the significant increment in dielectric anisotropy as well as faster diffusion of water along long molecular axis than short molecular axis has also been monitored. These studies strongly suggest that the distribution of water is anisotropic in FLC medium and could be the reason for new relaxation peak in the water added FLC sample. PMID:20866247

  5. Removal of non-ionic organic pollutants from water via liquid-liquid extraction.

    PubMed

    López-Montilla, Juan C; Pandey, Samir; Shah, Dinesh O; Crisalle, Oscar D

    2005-05-01

    The removal of model pollutants bromocresol green (BG) and phenol from water is demonstrated via two liquid-liquid extraction methods. Both methods exploit selective interactions established by the pollutant molecule with a surfactant, oil, or alcohol, and are variants of the more general Winsor systems where the phases are in contact along an extremely large interfacial area. In the first method the surfactant and the co-surfactant move from a predominantly oil-in-water microemulsion (Winsor I), to a middle phase microemulsion (Winsor III), and finally to a water-in-oil microemulsion (Winsor II), as the physicochemical conditions of salinity, temperature or hydrophilic-lipophilic balance of the surfactant system are varied. This method achieves better than 99% removal of the pollutant BG from water. It is argued that the removal is produced upon increasing the salinity of the system because the interaction of BG with a medium chain-length alcohol drives it to move along with the alcohol to another phase. The second method, which is scalable to industrial levels, uses a spontaneously produced water-in-oil microemulsion with large interfacial area that appears after bringing in contact water and a pre-formed Winsor II or Winsor III microemulsion system containing different surfactants and oils. The method is applied to the removal of phenol from water, and it is found that systems with polar oils such as ethyl butyrate or with cationic surfactants such as stearyl trimethylammonium chloride are more efficient in removing phenol than systems with normal alkanes or anionic surfactants. It is also shown that a microemulsion formed using a polar oil performs better than using only the polar oil as the extraction solvent. Finally, the efficiency of the second liquid-liquid extraction method can be increased from 69% in a single-stage process to 83% in a two-stage process, using the same total amount of extraction solvent. PMID:15899289

  6. Measurement of radiation damage of water-based liquid scintillator and liquid scintillator

    DOE PAGESBeta

    Bignell, L. J.; Diwan, M. V.; Hans, S.; Jaffe, D. E.; Rosero, R.; Vigdor, S.; Viren, B.; Worcester, E.; Yeh, M.; Zhang, C.

    2015-10-19

    Liquid scintillating phantoms have been proposed as a means to perform real-time 3D dosimetry for proton therapy treatment plan verification. We have studied what effect radiation damage to the scintillator will have upon this application. We have performed measurements of the degradation of the light yield and optical attenuation length of liquid scintillator and water-based liquid scintillator after irradiation by 201 MeV proton beams that deposited doses of approximately 52 Gy, 300 Gy, and 800 Gy in the scintillator. Liquid scintillator and water-based liquid scintillator (composed of 5% scintillating phase) exhibit light yield reductions of 1.74 ± 0.55 % andmore » 1.31 ± 0.59 % after ≈ 800 Gy of proton dose, respectively. Some increased optical attenuation was observed in the irradiated samples, the measured reduction to the light yield is also due to damage to the scintillation light production. Based on our results and conservative estimates of the expected dose in a clinical context, a scintillating phantom used for proton therapy treatment plan verification would exhibit a systematic light yield reduction of approximately 0.1% after a year of operation.« less

  7. Measurement of radiation damage of water-based liquid scintillator and liquid scintillator

    SciTech Connect

    Bignell, L. J.; Diwan, M. V.; Hans, S.; Jaffe, D. E.; Rosero, R.; Vigdor, S.; Viren, B.; Worcester, E.; Yeh, M.; Zhang, C.

    2015-10-19

    Liquid scintillating phantoms have been proposed as a means to perform real-time 3D dosimetry for proton therapy treatment plan verification. We have studied what effect radiation damage to the scintillator will have upon this application. We have performed measurements of the degradation of the light yield and optical attenuation length of liquid scintillator and water-based liquid scintillator after irradiation by 201 MeV proton beams that deposited doses of approximately 52 Gy, 300 Gy, and 800 Gy in the scintillator. Liquid scintillator and water-based liquid scintillator (composed of 5% scintillating phase) exhibit light yield reductions of 1.74 ± 0.55 % and 1.31 ± 0.59 % after ≈ 800 Gy of proton dose, respectively. Some increased optical attenuation was observed in the irradiated samples, the measured reduction to the light yield is also due to damage to the scintillation light production. Based on our results and conservative estimates of the expected dose in a clinical context, a scintillating phantom used for proton therapy treatment plan verification would exhibit a systematic light yield reduction of approximately 0.1% after a year of operation.

  8. Numerical studies on the separation performance of liquid- liquid Hydrocyclone for higher water-cut wells

    NASA Astrophysics Data System (ADS)

    Osei, H.; Al-Kayiem, H. H.; Hashim, F. M.

    2015-12-01

    Liquid-liquid hydrocyclones have nowadays become very useful in the oil industry because of their numerous applications. They can be installed downhole in the case of a well that produces higher water-oil ratios. The design of a liquid-liquid hydrocyclone for such a task is critical and every geometric part of the hydrocyclone has a part to play as far as separation is concerned. This work, through validated numerical technique, investigated the liquid-liquid hydrocyclone performance for the cases of single-inlet and dual-inlets, with different upper cylindrical lengths, specifically, 30mm and 60mm.It was observed that the hydrocyclones with the 30mm upper cylindrical section perform better than the ones with 60 mm upper cylindrical section. It was again noted that, even though higher number of tangential inlets increases the swirl intensity, they have the tendency to break up the oil droplets within the hydrocyclone because of increasing shear and jet flow interaction.

  9. A continuous mixture of two different dimers in liquid water.

    PubMed

    Pardo, L C; Henao, A; Busch, S; Guàrdia, E; Tamarit, J Ll

    2014-11-28

    It is hitherto thought that liquid water is composed of tetrahedrally coordinated molecules with an asymmetric interaction of the central molecule with neighboring molecules. Kühne et al., Nat. Commun., 2013, 4, 1450 suggested that this asymmetry, energetic rather than geometric, is the cornerstone to reconcile the homogeneous and inhomogeneous viewpoints of liquid water. In order to investigate the geometric origin of that asymmetry, we have scrutinized Molecular Dynamics (MD) simulations of water through a careful analysis of the five-dimensional probability distribution function of Euler angles in which the relative positions and orientations of water molecules are obtained. We demonstrate that, beyond the ubiquitous tetrahedral structure with well-defined molecular dimers, there is a series of possible molecular orientations that define the structure. These orientations are generated by rotating the neighboring molecule around the O-H axis that is involved in the hydrogen bond scheme. Two of the possible orientations have a higher probability, giving rise to two kinds of dimers: one close to the lowest energy of a water dimer in vacuum with an almost perpendicular alignment of the dipole moment, and another one with a parallel orientation of the dipole moment which is less tightly bound. These two different dimers have an effect on the orientation of further water dipole moments up to a distance of ≈6 Å. Liquid water can therefore be described as a continuous mixture of two kinds of dimers where the hydrogen bonds have the same geometry but the interaction energies are different due to a different mutual orientation of the dipoles of the participating water molecules. PMID:25308564

  10. Complete Wetting of Pt(111) by Nanoscale Liquid Water Films.

    PubMed

    Xu, Yuntao; Dibble, Collin J; Petrik, Nikolay G; Smith, R Scott; Kay, Bruce D; Kimmel, Greg A

    2016-02-01

    The melting and wetting of nanoscale crystalline ice films on Pt(111) that are transiently heated above the melting point in ultrahigh vacuum (UHV) using nanosecond laser pulses are studied with infrared reflection absorption spectroscopy and Kr temperature-programmed desorption. The as-grown crystalline ice films consist of nanoscale ice crystallites embedded in a hydrophobic water monolayer. Upon heating, these crystallites melt to form nanoscale droplets of liquid water. Rapid cooling after each pulse quenches the films, allowing them to be interrogated with UHV surface science techniques. With each successive heat pulse, these liquid drops spread across the surface until it is entirely covered with a multilayer water film. These results, which show that nanoscale water films completely wet Pt(111), are in contrast to molecular dynamics simulations predicting partial wetting of water drops on a hydrophobic water monolayer. The results provide valuable insights into the wetting characteristics of nanoscale water films on a clean, well-characterized, single-crystal surface. PMID:26785059

  11. Probing Hydrophilic Interface of Solid/Liquid-Water by Nanoultrasonics

    PubMed Central

    Mante, Pierre-Adrien; Chen, Chien-Cheng; Wen, Yu-Chieh; Chen, Hui-Yuan; Yang, Szu-Chi; Huang, Yu-Ru; -Ju Chen, I.; Chen, Yun-Wen; Gusev, Vitalyi; Chen, Miin-Jang; Kuo, Jer-Lai; Sheu, Jinn-Kong; Sun, Chi-Kuang

    2014-01-01

    Despite the numerous devoted studies, water at solid interfaces remains puzzling. An ongoing debate concerns the nature of interfacial water at a hydrophilic surface, whether it is more solid-like, ice-like, or liquid-like. To answer this question, a complete picture of the distribution of the water molecule structure and molecular interactions has to be obtained in a non-invasive way and on an ultrafast time scale. We developed a new experimental technique that extends the classical acoustic technique to the molecular level. Using nanoacoustic waves with a femtosecond pulsewidth and an ångström resolution to noninvasively diagnose the hydration structure distribution at ambient solid/water interface, we performed a complete mapping of the viscoelastic properties and of the density in the whole interfacial water region at hydrophilic surfaces. Our results suggest that water in the interfacial region possesses mixed properties and that the different pictures obtained up to now can be unified. Moreover, we discuss the effect of the interfacial water structure on the abnormal thermal transport properties of solid/liquid interfaces. PMID:25176017

  12. Structural studies and polymorphism in amorphous solids and liquids at high pressure.

    PubMed

    Wilding, Martin C; Wilson, Mark; McMillan, Paul F

    2006-10-01

    When amorphous materials are compressed their structures are expected to change in response to densification. In some cases, the changes in amorphous structure can be discontinuous and they can even have the character of first-order phase transitions. This is a phenomenon referred to as polyamorphism. Most evidence for polyamorphic transitions between low and high density liquids or analogous transformations between amorphous forms of the same substance to date has been indirect and based on the changes in thermodynamic and other structure-related properties with pressure. Recent studies using advanced X-ray and neutron scattering methods combined with molecular dynamics simulations are now revealing the details of structural changes in polyamorphic systems as a function of pressure. Various "two state" or "two species" models are used to understand the anomalous densification behaviour of liquids with melting curve maxima or regions of negative melting slope. Thermodynamic analysis of the two state model leads to the possibility of low- to high-density liquid transitions caused by differences in bulk thermodynamic properties between different amorphous forms and on the degree of cooperativity between low- and high-density structural configurations. The potential occurrence of first-order transitions between supercooled liquids is identified as a critical-like phenomenon. In this tutorial review we discuss the background to polyamorphism, incorporating the experimental observations, simulation studies and the two-state models. We also describe work carried on several systems that are considered to be polyamorphic. PMID:17003901

  13. Liquid-vapor oscillations of water in hydrophobic nanopores

    NASA Astrophysics Data System (ADS)

    Beckstein, Oliver; Sansom, Mark S. P.

    2003-06-01

    Water plays a key role in biological membrane transport. In ion channels and water-conducting pores (aquaporins), one-dimensional confinement in conjunction with strong surface effects changes the physical behavior of water. In molecular dynamics simulations of water in short (0.8 nm) hydrophobic pores the water density in the pore fluctuates on a nanosecond time scale. In long simulations (460 ns in total) at pore radii ranging from 0.35 to 1.0 nm we quantify the kinetics of oscillations between a liquid-filled and a vapor-filled pore. This behavior can be explained as capillary evaporation alternating with capillary condensation, driven by pressure fluctuations in the water outside the pore. The free-energy difference between the two states depends linearly on the radius. The free-energy landscape shows how a metastable liquid state gradually develops with increasing radius. For radii > 0.55 nm it becomes the globally stable state and the vapor state vanishes. One-dimensional confinement affects the dynamic behavior of the water molecules and increases the self diffusion by a factor of 2-3 compared with bulk water. Permeabilities for the narrow pores are of the same order of magnitude as for biological water pores. Water flow is not continuous but occurs in bursts. Our results suggest that simulations aimed at collective phenomena such as hydrophobic effects may require simulation times >50 ns. For water in confined geometries, it is not possible to extrapolate from bulk or short time behavior to longer time scales.

  14. Glass polymorphism in glycerol-water mixtures: I. A computer simulation study.

    PubMed

    Jahn, David A; Wong, Jessina; Bachler, Johannes; Loerting, Thomas; Giovambattista, Nicolas

    2016-04-28

    We perform out-of-equilibrium molecular dynamics (MD) simulations of water-glycerol mixtures in the glass state. Specifically, we study the transformations between low-density (LDA) and high-density amorphous (HDA) forms of these mixtures induced by compression/decompression at constant temperature. Our MD simulations reproduce qualitatively the density changes observed in experiments. Specifically, the LDA-HDA transformation becomes (i) smoother and (ii) the hysteresis in a compression/decompression cycle decreases as T and/or glycerol content increase. This is surprising given the fast compression/decompression rates (relative to experiments) accessible in MD simulations. We study mixtures with glycerol molar concentration χ(g) = 0-13% and find that, for the present mixture models and rates, the LDA-HDA transformation is detectable up to χ(g) ≈ 5%. As the concentration increases, the density of the starting glass (i.e., LDA at approximately χ(g) ≤ 5%) rapidly increases while, instead, the density of HDA remains practically constant. Accordingly, the LDA state and hence glass polymorphism become inaccessible for glassy mixtures with approximately χ(g) > 5%. We present an analysis of the molecular-level changes underlying the LDA-HDA transformation. As observed in pure glassy water, during the LDA-to-HDA transformation, water molecules within the mixture approach each other, moving from the second to the first hydration shell and filling the first interstitial shell of water molecules. Interestingly, similar changes also occur around glycerol OH groups. It follows that glycerol OH groups contribute to the density increase during the LDA-HDA transformation. An analysis of the hydrogen bond (HB)-network of the mixtures shows that the LDA-HDA transformation is accompanied by minor changes in the number of HBs of water and glycerol. Instead, large changes in glycerol and water coordination numbers occur. We also perform a detailed analysis of the effects that

  15. A single-site multipole model for liquid water

    NASA Astrophysics Data System (ADS)

    Tran, Kelly N.; Tan, Ming-Liang; Ichiye, Toshiko

    2016-07-01

    Accurate and efficient empirical potential energy models that describe the atomistic interactions between water molecules in the liquid phase are essential for computer simulations of many problems in physics, chemistry, and biology, especially when long length or time scales are important. However, while models with non-polarizable partial charges at four or five sites in a water molecule give remarkably good values for certain properties, deficiencies have been noted in other properties and increasing the number of sites decreases computational efficiency. An alternate approach is to utilize a multipole expansion of the electrostatic potential due to the molecular charge distribution, which is exact outside the charge distribution in the limits of infinite distances or infinite orders of multipoles while partial charges are a qualitative representation of electron density as point charges. Here, a single-site multipole model of water is presented, which is as fast computationally as three-site models but is also more accurate than four- and five-site models. The dipole, quadrupole, and octupole moments are from quantum mechanical-molecular mechanical calculations so that they account for the average polarization in the liquid phase, and represent both the in-plane and out-of-plane electrostatic potentials of a water molecule in the liquid phase. This model gives accurate thermodynamic, dynamic, and dielectric properties at 298 K and 1 atm, as well as good temperature and pressure dependence of these properties.

  16. Water Tank with Capillary Air/Liquid Separation

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Smith, Frederick; Edeen, Gregg; Almlie, Jay C.

    2010-01-01

    A bladderless water tank (see figure) has been developed that contains capillary devices that allow it to be filled and emptied, as needed, in microgravity. When filled with water, the tank shields human occupants of a spacecraft against cosmic radiation. A membrane that is permeable by air but is hydrophobic (neither wettable nor permeable by liquid water) covers one inside surface of the tank. Grooves between the surface and the membrane allow air to flow through vent holes in the surface as the tank is filled or drained. A margin of wettable surface surrounds the edges of the membrane, and all the other inside tank surfaces are also wettable. A fill/drain port is located in one corner of the tank and is covered with a hydrophilic membrane. As filling begins, water runs from the hydrophilic membrane into the corner fillets of the tank walls. Continued filling in the absence of gravity will result in a single contiguous air bubble that will be vented through the hydrophobic membrane. The bubble will be reduced in size until it becomes spherical and smaller than the tank thickness. Draining the tank reverses the process. Air is introduced through the hydrophobic membrane, and liquid continuity is maintained with the fill/drain port through the corner fillets. Even after the tank is emptied, as long as the suction pressure on the hydrophilic membrane does not exceed its bubble point, no air will be drawn into the liquid line.

  17. A single-site multipole model for liquid water.

    PubMed

    Tran, Kelly N; Tan, Ming-Liang; Ichiye, Toshiko

    2016-07-21

    Accurate and efficient empirical potential energy models that describe the atomistic interactions between water molecules in the liquid phase are essential for computer simulations of many problems in physics, chemistry, and biology, especially when long length or time scales are important. However, while models with non-polarizable partial charges at four or five sites in a water molecule give remarkably good values for certain properties, deficiencies have been noted in other properties and increasing the number of sites decreases computational efficiency. An alternate approach is to utilize a multipole expansion of the electrostatic potential due to the molecular charge distribution, which is exact outside the charge distribution in the limits of infinite distances or infinite orders of multipoles while partial charges are a qualitative representation of electron density as point charges. Here, a single-site multipole model of water is presented, which is as fast computationally as three-site models but is also more accurate than four- and five-site models. The dipole, quadrupole, and octupole moments are from quantum mechanical-molecular mechanical calculations so that they account for the average polarization in the liquid phase, and represent both the in-plane and out-of-plane electrostatic potentials of a water molecule in the liquid phase. This model gives accurate thermodynamic, dynamic, and dielectric properties at 298 K and 1 atm, as well as good temperature and pressure dependence of these properties. PMID:27448890

  18. Liquid Hot Water Pretreatment of Olive Tree Pruning Residues

    NASA Astrophysics Data System (ADS)

    Cara, Cristóbal; Romero, Inmaculada; Oliva, Jose Miguel; Sáez, Felicia; Castro, Eulogio

    Olive tree pruning generates an abundant, renewable lignocellulose residue, which is usually burnt on fields to prevent propagation of vegetal diseases, causing economic costs and environmental concerns. As a first step in an alternative use to produce fuel ethanol, this work is aimed to study the pretreatment of olive tree pruning residues by liquid hot water. Pretreatment was carried out at seven temperature levels in the range 170-230°C for 10 or 60 min. Sugar recoveries in both solid and liquid fractions resulting from pretreatment as well as enzymatic hydrolysis yield of the solid were used to evaluate pretreatment performance. Results show that the enzyme accessibility of cellulose in the pretreated solid fraction increased with pretreatment time and temperature, although sugar degradation in the liquid fraction was concomitantly higher.

  19. Hydrophobicity and hydrogen-bonded network in liquid water

    NASA Astrophysics Data System (ADS)

    Li, Je-Luen; Wingreen, Ned; Tang, Chao; Car, Roberto

    2004-03-01

    Hydrophobicity is the main driving force behind numerous important biological processes at molecular level, including protein folding and the formation of biological membranes. Yet few experimental probes can measure the local water structure around a hydrophobic solute, and our understanding of the detailed structure of hydrophobic hydration has to rely on molecular dynamics simulation. As a model system, several groups studied two methane molecules in liquid water and obtained the potential of mean force using Lennard-Jones potential and various water models. However, hydrophobic effect critically depends on the description of hydrogen-bonded network, and classical simulations may not be sufficient to descirbe the forming and breaking of hydrogen bonds. In this work, we apply ab initio molecular dynamics simulations to study this model system. Besides the potential of mean force between 2 methanes in water, the role of the local water structure will be highlighted.

  20. Interplay between Microscopic Diffusion and Local Structure of Liquid Water

    SciTech Connect

    Cunsolo, A.; Orecchini, A; Petrillo, C.; Sacchetti, F.

    2010-11-29

    We present a quasielastic neutron scattering (QENS) study of single-particle dynamics in pure water, measured at temperatures between 256 and 293 K along an isobaric path at 200 MPa. A thorough analysis of the spectral line shapes reveals a departure from simple models of continuous or jump diffusion, with such an effect becoming stronger at lower temperatures. We show that such a diverging trend of dynamical quantities upon cooling closely resembles the divergent (anomalous) compressibility observed in water by small-angle diffraction. Such an analogy suggests an interesting interplay between single-particle diffusion and structural arrangements in liquid water, both bearing witness of the well-known water anomalies. In particular, a fit of dynamical parameters by a Vogel-Tammann-Fulcher law provides a critical temperature of about 220 K, interestingly close to the hypothesized position of the second critical point of water and to the so-called Widom line.

  1. Glass polymorphism in glycerol–water mixtures: I. A computer simulation study

    PubMed Central

    Jahn, David A.; Wong, Jessina; Bachler, Johannes; Loerting, Thomas

    2016-01-01

    We perform out-of-equilibrium molecular dynamics (MD) simulations of water–glycerol mixtures in the glass state. Specifically, we study the transformations between low-density (LDA) and high-density amorphous (HDA) forms of these mixtures induced by compression/decompression at constant temperature. Our MD simulations reproduce qualitatively the density changes observed in experiments. Specifically, the LDA–HDA transformation becomes (i) smoother and (ii) the hysteresis in a compression/decompression cycle decreases as T and/or glycerol content increase. This is surprising given the fast compression/decompression rates (relative to experiments) accessible in MD simulations. We study mixtures with glycerol molar concentration χ g = 0–13% and find that, for the present mixture models and rates, the LDA–HDA transformation is detectable up to χ g ≈ 5%. As the concentration increases, the density of the starting glass (i.e., LDA at approximately χ g ≤ 5%) rapidly increases while, instead, the density of HDA remains practically constant. Accordingly, the LDA state and hence glass polymorphism become inaccessible for glassy mixtures with approximately χ g > 5%. We present an analysis of the molecular-level changes underlying the LDA–HDA transformation. As observed in pure glassy water, during the LDA-to-HDA transformation, water molecules within the mixture approach each other, moving from the second to the first hydration shell and filling the first interstitial shell of water molecules. Interestingly, similar changes also occur around glycerol OH groups. It follows that glycerol OH groups contribute to the density increase during the LDA–HDA transformation. An analysis of the hydrogen bond (HB)-network of the mixtures shows that the LDA–HDA transformation is accompanied by minor changes in the number of HBs of water and glycerol. Instead, large changes in glycerol and water coordination numbers occur. We also perform a detailed analysis of the

  2. Bulk and interfacial liquid water as a transient network.

    PubMed

    Jahn, Miriam; Gekle, Stephan

    2015-11-01

    The special macroscopic properties of liquid water stem from its structure as a complex network of molecules connected by hydrogen bonds. While the dynamics of single molecules within this network has been extensively investigated, only little attention has been paid to the closed loops (meshes) of hydrogen-bonded molecules which determine the network topology. Using molecular dynamics simulations we analyze the size, shape, geometrical arrangement, and dynamical stability of loops containing up to 10 hydrogen bonds. We find that six-membered loops in liquid water even at room temperature retain a striking similarity with the well-known structure of ice. Analyzing the network dynamics we find that rings of more than five hydrogen bonds are stabilized compared to a random collection containing the same number of single bonds. We finally show that in the vicinity of hydrophobic and hydrophilic interfaces loops arrange in a preferred orientation. PMID:26651669

  3. Time-dependent density fluctuations in liquid water

    NASA Astrophysics Data System (ADS)

    Waldron, Conor J.; English, Niall J.

    2016-04-01

    Temporal system-mass-density fluctuation analysis was performed on liquid-water molecular-dynamics simulations at ambient pressure and 200 and 300 K, in three increasingly-large systems. A prominent mode in system-density fluctuations was observed at molecular-librational frequencies of ∼600-800 cm-1 (with pronounced temperature dependence). This mode displayed marked system-size dependence, disappearing for larger systems. Persistent system-density fluctuations were clearly evident at 10-11 cm-1 for all systems and temperatures, with lower-amplitude 'overtones' evident only in larger systems. It is conjectured that this reflects ∼3 ps timescales observed in earlier studies for dissipation of local-density fluctuations in liquid water in this 200-300 K temperature range.

  4. Stable and water-tolerant ionic liquid ferrofluids.

    PubMed

    Jain, Nirmesh; Zhang, Xiaoli; Hawkett, Brian S; Warr, Gregory G

    2011-03-01

    Ionic liquid ferrofluids have been prepared containing both bare and sterically stabilized 8-12 nm diameter superparamagnetic iron oxide nanoparticles, which remain stable for several months in both protic ethylammonium and aprotic imidazolium room-temperature ionic liquids. These ferrofluids exhibit spiking in static magnetic fields similar to conventional aqueous and nonaqueous ferrofluids. Ferrofluid stability was verified by following the flocculation and settling behavior of dilute nanoparticle dispersions. Although bare nanoparticles showed excellent stability in some ILs, they were unstable in others, and exhibited limited water tolerance. Stability was achieved by incorporating a thin polymeric steric stabilization layer designed to be compatible with the IL. This confers the added benefit of imbuing the ILF with a high tolerance to water. PMID:21338083

  5. Nucleationand surface induced crystallization in supercooled liquid water

    NASA Astrophysics Data System (ADS)

    Russo, Giovanna; Li, Tianshu; Donadio, Davide; Galli, Giulia

    2010-03-01

    Understanding crystallization of water into ice is a very challenging problem, both experimentally and theoretically; in particular, the spatial and temporal resolutions required to characterize the crystallization process at the atomic scale are not yet accessible to experiment. Here we employ a combination of molecular dynamics simulations and advanced sampling techniques to study nucleation in supercooled liquid water. Recently, such an approach has been successfully applied to study nucleation in supercooled liquid silicon [1,2]. The results of our simulations, carried out using a coarse grain potential [3], are used to analyze nucleation rates at various temperatures and to investigate the role played by the presence of surfaces in the freezing processes. [4pt] [1] T. Li, D. Donadio and G. Galli, Nat. Mat. 9, 726730 (2009)[0pt] [2] T. Li, D. Donadio and G. Galli, J. Chem. Phys., in press[0pt] [3] V. Molinero and E. B. Moore J. Phys. Chem. B 113, 40084016 (2009)

  6. Dispersive liquid-liquid microextraction of silver nanoparticles in water using ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate.

    PubMed

    Chen, Sha; Sun, Yuanjing; Chao, Jingbo; Cheng, Liping; Chen, Yun; Liu, Jingfu

    2016-03-01

    Using the ionic liquid (IL) 1-octyl-3-methylimidazolium hexafluorophosphate as the extractant and methanol as the dispersion solvent, a dispersive liquid-liquid microextraction method was developed to extract silver nanoparticles (AgNPs) from environmental water samples. Parameters that influenced the extraction efficiency such as IL concentration, pH and extraction time were optimized. Under the optimized conditions, the highest extraction efficiency for AgNPs was above 90% with an enrichment factor of >90. The extracted AgNPs in the IL phase were identified by transmission electron microscopy and ultraviolet-visible spectroscopy, and quantified by inductively coupled plasma mass spectrometry after microwave digestion, with a detection limit of 0.01μg/L. The spiked recovery of AgNPs was 84.4% with a relative standard deviation (RSD) of 3.8% (n=6) at a spiked level of 5μg/L, and 89.7% with a RSD of 2.2% (n=6) at a spiked level of 300μg/L, respectively. Commonly existed environmental ions had a very limited influence on the extraction efficiency. The developed method was successfully applied to the analysis of AgNPs in river water, lake water, and the influent and effluent of a wastewater treatment plant, with recoveries in the range of 71.0%-90.9% at spiking levels of 0.11-4.7μg/L. PMID:26969067

  7. Investigating evidence of geologically recent liquid water on Mars

    NASA Astrophysics Data System (ADS)

    Kolb, Kelly Jean

    2009-06-01

    Geologically young gullies have been proposed to be evidence of recent liquid water on Mars. This dissertation details work I have done to address issues surrounding the Martian gullies and recent water on Mars. In order to determine the elevations at which gullies occur, I created a set of Interactive Data Language programs and Unix C-shell scripts to coregister Mars Orbiter Laser Altimeter topography with high resolution Mars images. My scripts represent the first public method that does this. Recently, the Mars Orbiter Camera detected changes in the form of new bright deposits in two gullies. The High Resolution Imaging Science Experiment (HiRISE) camera detected more gullies with bright deposits. I used my scripts to identify some of the best candidates for liquid water formation based on their shallow average slopes. A Digital Elevation Model (DEM) was produced using HiRISE stereo images of my selected candidates in Hale Crater. I model two gullies with bright slope deposits in Hale Crater and find that both water- rich and sediment-rich flows could reproduce the bright deposits' locations and morphologies. Since liquid water is rarely stable on Mars today, I suggest that dry flows formed the bright deposits. The channel gradient where flows deposit, the apex slope, can tell us whether a flow was likely dry and non-fluidized (slopes ~21°) or fluidized (shallower slopes). I measured the apex slope of 75 gullies located in five HiRISE DEMs. I find that 72% of the gullies studied were likely emplaced by a fluidized flow. I also find that modified gullies are more likely to have a fluidized emplacement than relatively fresh gullies. My results suggest that there is no evidence requiring water-rich flows in gullies today. Understanding the concept of water on Mars is crucial to understanding NASA's Mars Exploration Strategy, "Follow the Water." I undertook a study investigating alternative conceptions about water on Mars held by middle school science teachers to

  8. Phase Behavior and Collective Dynamics of Liquid Water

    NASA Astrophysics Data System (ADS)

    Sastry, Srikanth

    The unusual properties of liquid water have been analyzed predominantly in terms of the hydrogen bond network which characterizes its microscopic structure. Properties of the hydrogen bond network, with physically motivated additional assumptions, have been shown to describe well most static and dynamic properties of water. However, there are important exceptions where no conclusive analysis in terms of the hydrogen bond network has been carried out. Two such exceptions are addressed in this thesis. The phase behaviour of water--in particular the limiting behavior of the metastable continuations of the liquid--is an open question. To explain the apparent divergence of many thermodynamic and microscopic quantities on supercooling, Speedy and Angell proposed that these divergences are due to an absolute limit of stability of the liquid phase, conjecturing further that such limits of stability form a continuous reentrant locus in the P-T plane. In an attempt to address this conjecture on the basis of microscopic behavior in water, a lattice gas model is developed, which exhibits water-like behavior and has phases corresponding to the real system. The liquid gas spinodal is seen to be reentrant, in accordance with the stability limit conjecture. However, the limit of stability upon supercooling in the model, while consistent with experiments, is found to differ qualitatively from the prediction, displaying no singular behavior of thermodynamic quantities. In computer and experimental studies of sound propagation in water at high wavenumbers, the sound velocity is found to be about twice the hydrodynamic value. It was proposed that this mode propagates on the hydrogen bond network and occurs due to the connectivity properties of the network. This question is studied through Molecular Dynamics simulations of the liquid and normal model analysis of inherent structures. The results show that only one longitudinal sound mode is present. However, an attempt is made to go

  9. Ionic-liquid-based dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the determination of multiclass pesticide residues in water samples.

    PubMed

    Tadesse, Bezuayehu; Teju, Endale; Gure, Abera; Megersa, Negussie

    2015-03-01

    Ionic-liquid-based dispersive liquid-liquid microextraction in combination with high-performance liquid chromatography and diode array detection has been proposed for the simultaneous analysis of four multiclass pesticide residues including carbaryl, methidathion, chlorothalonil, and ametryn from water samples. The major experimental parameters including the type and volume of ionic liquid, sample pH, type, and volume of disperser solvent and cooling time were investigated and optimum conditions were established. Under the optimum experimental conditions, limits of detection and quantification of the method were in the range of 0.1-1.8 and 0.4-5.9 μg/L, respectively, with satisfactory enrichment factors ranging from 10-20. The matrix-matched calibration curves, which were constructed for lake water, as a representative matrix were linear over wide range with coefficients of determination of 0.996 or better. Intra- and interday precisions, expressed as relative standard deviations, were in the range of 1.1-9.7 and 3.1-7.8%, respectively. The relative recoveries of the spiked environmental water samples at one concentration level were in the range of 77-102%. The results of the present study revealed that the proposed method is simple, fast, and uses environmentally friendly extraction solvent for the analysis of the target pesticide residues in environmental water samples. PMID:25641819

  10. Interfacial Transport Phenomena Stability in Liquid-Metal/Water Systems

    SciTech Connect

    Michael Corradini; Anderson, Mark; Bonazza, Riccardo; Cho, D. H.

    2002-12-19

    One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area can give rise to large heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability.In order to investigate the characteristics of such a molten metal/water direct contact heat exchanger, a series of experiments were performed in both a 1-D and 2-d experimental facility. The facilities primarily consist of a liquid-metal melt chamber, heated test section, water pumping/injection system, and steam suppression tank (condenser). A real-time high energy X-ray imaging system along with several temperature measurements and flow measurements were developed and utilized to measure the multiphase flow and obtain an empirical database of local as well as overall system parameters. Results have found volumetric void fraction between 0.05-0.2, overall volumetric heat transfer coefficient ranging from 4-20 kW/m3K, evaporation zone lengths on the order of 10cm and local heat transfer coefficients varying between 500-5000 W/m2K depending on the inlet water injection conditions and system pressure. Time-dependent void fraction distribution and generated water-vapor bubble characteristics (i.e. bubble formation rate, bubble rise velocity, and bubble surface area) were measured using an X-ray image analysis technique. These measurements aided in the determination of the volumetric thermal performance as well as well as the first detailed information on local interfacial phenomenon. This information in turn resulted in the first experimental measurements of the local heat transfer coefficient

  11. Optically Thin Liquid Water Clouds: Their Importance and Our Challenge

    NASA Technical Reports Server (NTRS)

    Turner, D. D.; Vogelmann, A. M.; Austin, R. T.; Barnard, J. C.; Cady-Pereira, K.; Chiu, J. C.; Clough, S. A.; Flynn, C.; Khaiyer, M. M.; Liljegren, J.; Johnson, K.; Lin, B.; Long, C.; Marshak, A.; Matrosov, S. Y.; McFarlane, S. A.; Miller, M.; Min, Q.; Minnis, P.; O'Hirok, W.; Wang, Z.; Wiscombe, W.

    2006-01-01

    Many of the clouds important to the Earth's energy balance, from the tropics to the Arctic, are optically thin and contain liquid water. Longwave and shortwave radiative fluxes are very sensitive to small perturbations of the cloud liquid water path (LWP) when the liquid water path is small (i.e., < g/sq m) and, thus, the radiative properties of these clouds must be well understood to capture them correctly in climate models. We review the importance of these thin clouds to the Earth's energy balance, and explain the difficulties in observing them. In particular, because these clouds are optically thin, potentially mixed-phase, and often (i.e., have large 3-D variability), it is challenging to retrieve their microphysical properties accurately. We describe a retrieval algorithm intercomparison that was conducted to evaluate the issues involved. The intercomparison included eighteen different algorithms to evaluate their retrieved LWP, optical depth, and effective radii. Surprisingly, evaluation of the simplest case, a single-layer overcast cloud, revealed that huge discrepancies exist among the various techniques, even among different algorithms that are in the same general classification. This suggests that, despite considerable advances that have occurred in the field, much more work must be done, and we discuss potential avenues for future work.

  12. Thermally driven electrokinetic energy conversion with liquid water microjets

    NASA Astrophysics Data System (ADS)

    Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; Saykally, Richard J.

    2015-11-01

    A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.

  13. Measuring Low Concentrations of Liquid Water in Soil

    NASA Technical Reports Server (NTRS)

    Buehler, Martin

    2009-01-01

    An apparatus has been developed for measuring the low concentrations of liquid water and ice in relatively dry soil samples. Designed as a prototype of instruments for measuring the liquidwater and ice contents of Lunar and Martian soils, the apparatus could also be applied similarly to terrestrial desert soils and sands. The apparatus is a special-purpose impedance spectrometer: Its design is based on the fact that the electrical behavior of a typical soil sample is well approximated by a network of resistors and capacitors in which resistances decrease and capacitances increase (and, hence, the magnitude of impedance decreases) with increasing water content.

  14. Electrons and Hydrogen-Bond Connectivity in Liquid Water

    SciTech Connect

    Fernandez-Serra, M.V.; Artacho, Emilio

    2006-01-13

    The network connectivity in liquid water is revised in terms of electronic signatures of hydrogen bonds (HBs) instead of geometric criteria, in view of recent x-ray absorption studies. The analysis is based on ab initio molecular-dynamics simulations at ambient conditions. Even if instantaneous threadlike structures are observed in the electronic network, they continuously reshape in oscillations reminiscent of the r and t modes in ice ({tau}{approx}170 fs). However, two water molecules initially joined by a HB remain effectively bound over many periods regardless of its electronic signature.

  15. Liquid water can slip on a hydrophilic surface

    PubMed Central

    Ho, Tuan Anh; Papavassiliou, Dimitrios V.; Lee, Lloyd L.; Striolo, Alberto

    2011-01-01

    Understanding and predicting the behavior of water, especially in contact with various surfaces, is a scientific challenge. Molecular-level understanding of hydrophobic effects and their macroscopic consequences, in particular, is critical to many applications. Macroscopically, a surface is classified as hydrophilic or hydrophobic depending on the contact angle formed by a water droplet. Because hydrophobic surfaces tend to cause water slip whereas hydrophilic ones do not, the former surfaces can yield self-cleaning garments and ice-repellent materials whereas the latter cannot. The results presented herein suggest that this dichotomy might be purely coincidental. Our simulation results demonstrate that hydrophilic surfaces can show features typically associated with hydrophobicity, namely liquid water slip. Further analysis provides details on the molecular mechanism responsible for this surprising result. PMID:21911406

  16. Liquid polymorphism and density anomaly in a three-dimensional associating lattice gas.

    PubMed

    Girardi, Mauricio; Balladares, Aline L; Henriques, Vera B; Barbosa, Marcia C

    2007-02-14

    The authors investigate the phase diagram of a three-dimensional associating lattice gas (ALG) model. This model combines orientational icelike interactions and "van der Waals" that might be repulsive, representing, in this case, a penalty for distortion of hydrogen bonds. These interactions can be interpreted as two competing distances, making the connection between this model and continuous isotropic soft-core potentials. The authors present Monte Carlo studies of the ALG model showing the presence of two liquid phases, two critical points, and density anomaly. PMID:17313225

  17. A new analytic equation of state for liquid water

    NASA Astrophysics Data System (ADS)

    Jeffery, C. A.; Austin, P. H.

    1999-01-01

    We develop a new analytical equation of state for water based on the Song, Mason, and Ihm equation of state and Poole et al.'s simple model of the free energy of strong tetrahedral hydrogen bonds. Repulsive and attractive forces are modeled using a modification of the Weeks-Chandler-Anderson decomposition of the pair potential, with closed tetrahedral hydrogen bonds contributing both internal energy and entropy to the free energy of water. Strong tetrahedral hydrogen bonds are modeled explicitly using a simplified partition function. The resulting equation of state is 20-30 times more accurate than equivalent simple cubic equations of state over a wide range of pressures (0.1→3000 bar) and temperatures (-34→1200 °C) including the supercooled region. The new equation of state predicts a second liquid-liquid critical point at pC'=0.954 kbar, ρC'=1.045 g cm-3 and TC'=228.3 K. The temperature of this second critical point is above the homogeneous freezing temperature at 1 kbar, thus this region of the phase diagram may be experimentally accessible. The phase diagram also suggests that the homogeneous nucleation temperature above 1.2 kbar may be determined by a phase transition from high-density water to low-density water.

  18. Transformation of acidic poorly water soluble drugs into ionic liquids.

    PubMed

    Balk, Anja; Wiest, Johannes; Widmer, Toni; Galli, Bruno; Holzgrabe, Ulrike; Meinel, Lorenz

    2015-08-01

    Poor water solubility of active pharmaceutical ingredients (API) is a major challenge in drug development impairing bioavailability and therapeutic benefit. This study is addressing the possibility to tailor pharmaceutical and physical properties of APIs by transforming these into tetrabutylphosphonium (TBP) salts, including the generation of ionic liquids (IL). Therefore, poorly water soluble acidic APIs (Diclofenac, Ibuprofen, Ketoprofen, Naproxen, Sulfadiazine, Sulfamethoxazole, and Tolbutamide) were converted into TBP ILs or low melting salts and compared to the corresponding sodium salts. Free acids and TBP salts were characterized by NMR and IR spectroscopy, DSC and XRPD, DVS and dissolution rate measurements, release profiles, and saturation concentration measurements. TBP salts had lower melting points and glass transition temperatures and dissolution rates were improved up to a factor of 1000 as compared to the corresponding free acid. An increase in dissolution rates was at the expense of increased hygroscopicity. In conclusion, the creation of TBP ionic liquids or solid salts from APIs is a valuable concept addressing dissolution and solubility challenges of poorly water soluble acidic compounds. The data suggested that tailor-made counterions may substantially expand the formulation scientist's armamentarium to meet challenges of poorly water soluble drugs. PMID:25976317

  19. Calculation of heavy-ion tracks in liquid water

    SciTech Connect

    Hamm, R.N.; Turner, J.E.; Ritchie, R.H.; Wright, H.A.

    1985-01-01

    Detailed Monte Carlo calculations are presented of proton and alpha-particle tracks in liquid water. The computations treat the interactions of the primary particle and all secondary electrons on a statistical, event-by-event basis to simulate the initial physical changes that accompany the passage of an ion through water. Our methods for obtaining the cross sections needed for such calculations are described. Inelastic scattering probabilities (inverse mean free paths) are derived from a complex dielectric response function constructed for liquid water, based on experimental and theoretical data. Examples of partial cross sections for ionization and excitation by protons are shown. The computation of electron transport and energy loss includes exchange, elastic scattering, and a scheme for the delocalization of energy shared collectively by a large number of electrons in the condensed medium. Several examples of calculated proton and alpha-particle tracks are presented and discussed. The meaning and significance of the concept of a ''track core'' is briefly addressed in the light of this work. The present paper treats only the initial, physical changes produced by radiation in water (in approx. 10/sup -15/ sec in local regions of a track). The work described here is used in calculations that we have reported in other publications on the later chemical development of charged-particle tracks. 10 refs., 6 figs.

  20. Fractionation of sugar cane with hot, compressed, liquid water

    SciTech Connect

    Allen, S.G.; Kam, L.C.; Zemann, A.J.; Antal, M.J. Jr.

    1996-08-01

    Sugar-cane bagasse and leaves (10--15 g oven-dry basis) were fractionated without size reduction by a rapid (45 s to 4 min), immersed percolation using only hot (190--230 C), compressed (P > P{sub sat}), liquid water (0.6--1.2 kg). Over 50% of the biomass could be solubilized. All of the hemicellulose, together with much of the acid-insoluble lignin in the bagasse (>60%), was solubilized, while less than 10% of the cellulose entered the liquid phase. Moreover, recovery of the hemicellulose as monomeric sugars (after a mild posthydrolysis) exceeded 80%. Less than 5% of the hemicellulose was converted to furfural. Percolation beyond that needed to immerse the biomass in hot liquid water did not result in increased solubilization. The yield of lignocellulosic residue was also not sensitive to the form of the sugar cane used (bagasse or leaves) or its moisture content (8--50%). Commercial applications for this fractionation process include the pretreatment of lignocellulosics for bioconversion to ethanol and the production of pulp and paper products.

  1. Transient liquid water and water activity at Gale crater on Mars

    NASA Astrophysics Data System (ADS)

    Martín-Torres, F. Javier; Zorzano, María-Paz; Valentín-Serrano, Patricia; Harri, Ari-Matti; Genzer, Maria; Kemppinen, Osku; Rivera-Valentin, Edgard G.; Jun, Insoo; Wray, James; Bo Madsen, Morten; Goetz, Walter; McEwen, Alfred S.; Hardgrove, Craig; Renno, Nilton; Chevrier, Vincent F.; Mischna, Michael; Navarro-González, Rafael; Martínez-Frías, Jesús; Conrad, Pamela; McConnochie, Tim; Cockell, Charles; Berger, Gilles; R. Vasavada, Ashwin; Sumner, Dawn; Vaniman, David

    2015-05-01

    Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover, lowers the freezing temperature of water. Moreover, perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere-soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.

  2. Solvation structures of water in trihexyltetradecylphosphonium-orthoborate ionic liquids

    NASA Astrophysics Data System (ADS)

    Wang, Yong-Lei; Sarman, Sten; Kloo, Lars; Antzutkin, Oleg N.; Glavatskih, Sergei; Laaksonen, Aatto

    2016-08-01

    Atomistic molecular dynamics simulations have been performed to investigate effective interactions of isolated water molecules dispersed in trihexyltetradecylphosphonium-orthoborate ionic liquids (ILs). The intrinsic free energy changes in solvating one water molecule from gas phase into bulk IL matrices were estimated as a function of temperature, and thereafter, the calculations of potential of mean force between two dispersed water molecules within different IL matrices were performed using umbrella sampling simulations. The systematic analyses of local ionic microstructures, orientational preferences, probability and spatial distributions of dispersed water molecules around neighboring ionic species indicate their preferential coordinations to central polar segments in orthoborate anions. The effective interactions between two dispersed water molecules are partially or totally screened as their separation distance increases due to interference of ionic species in between. These computational results connect microscopic anionic structures with macroscopically and experimentally observed difficulty in completely removing water from synthesized IL samples and suggest that the introduction of hydrophobic groups to central polar segments and the formation of conjugated ionic structures in orthoborate anions can effectively reduce residual water content in the corresponding IL samples.

  3. A "First Principles" Potential Energy Surface for Liquid Water from VRT Spectroscopy of Water Clusters

    SciTech Connect

    Goldman, N; Leforestier, C; Saykally, R J

    2004-05-25

    We present results of gas phase cluster and liquid water simulations from the recently determined VRT(ASP-W)III water dimer potential energy surface. VRT(ASP-W)III is shown to not only be a model of high ''spectroscopic'' accuracy for the water dimer, but also makes accurate predictions of vibrational ground-state properties for clusters up through the hexamer. Results of ambient liquid water simulations from VRT(ASP-W)III are compared to those from ab initio Molecular Dynamics, other potentials of ''spectroscopic'' accuracy, and to experiment. The results herein represent the first time that a ''spectroscopic'' potential surface is able to correctly model condensed phase properties of water.

  4. Local order of liquid water at the electrochemical interface

    NASA Astrophysics Data System (ADS)

    Fernandez Serra, Marivi; Pedroza, Luana

    2014-03-01

    Understanding the aqueous electrochemical interface in an atomic level is of fundamental importance in many areas, such as catalysis and materials science. In this work we analyze in detail the structural, dynamic and energetic properties of liquid-water interacting with (111) Pd and Au surfaces at ambient temperature, using first principles molecular dynamics, with and without van der Waals interactions. We show that, contrary to what was found when studying ice-like water layers, van der Waals interactions play a critical role in modeling the aqueous/electrode interface. We show the differences in the ordering of water at the interface for Pd and Au, and we explain the change in work functions of these two metals in aqueous solution. DOE Early Career Award No. DE-SC0003871.

  5. Structure and dynamics of complex liquid water: Molecular dynamics simulation

    NASA Astrophysics Data System (ADS)

    S, Indrajith V.; Natesan, Baskaran

    2015-06-01

    We have carried out detailed structure and dynamical studies of complex liquid water using molecular dynamics simulations. Three different model potentials, namely, TIP3P, TIP4P and SPC-E have been used in the simulations, in order to arrive at the best possible potential function that could reproduce the structure of experimental bulk water. All the simulations were performed in the NVE micro canonical ensemble using LAMMPS. The radial distribution functions, gOO, gOH and gHH and the self diffusion coefficient, Ds, were calculated for all three models. We conclude from our results that the structure and dynamical parameters obtained for SPC-E model matched well with the experimental values, suggesting that among the models studied here, the SPC-E model gives the best structure and dynamics of bulk water.

  6. Liquid-liquid coexistence and crystallization in supercooled ST2 water

    NASA Astrophysics Data System (ADS)

    Martelli, Fausto; Palmer, Jeremy; Debenedetti, Pablo; Car, Roberto

    2014-03-01

    We have computed the free energy landscape of ST2 water in the supercooled regime (228.6 K and 2.4 kbar) using several state-of-the-art computational techniques, including umbrella sampling and metadynamics. Such results conclusively demonstrate coexistence between two liquid phases, a high-density liquid (HDL) and a low-density liquid (HDL), which are metastable with respect to cubic ice. We show that the three phases have distinct structural features characterized by the local structure index and ring statistics. We also find that ice nucleation, should it occur, does so from the low-density liquid. Interestingly, we find that the number of 6-member rings increases monotonically along the path from HDL to LDL, while non-monotonic behavior is observed near the saddle point along the LDL-ice Ic path. This behavior indicates a complex re-arrangement of the H-bond network, followed by progressive crystallization. DOE: DE-SC0008626 (F. M. and R.C.)

  7. Development of liquid-liquid cylindrical cyclone (LLCC) separator for oil-water separation

    NASA Astrophysics Data System (ADS)

    Dharma, Irfan Aditya; Arffan, Fuad; Prambudi, Anggi Riyo; Widyaparaga, Adhika; Pranoto, Indro; Khasani

    2016-06-01

    This study aims to determine the phenomena of water and oil separation and the performance of the Liquid-Liquid Cylindrical Cyclone (LLCC). The experiments were conducted with water and oil in a transparent LLCC separator that allows the visualization of the mixture. Series of experiments for various of inlet mixture velocity (Vm), inlet oil volume fraction (α), and split-ratio have been performed. Volume fraction of oil in the inlet were 0.06 (6 %), 0.1 (10%), and 0.15 (15 %). The examined inlet mixture velocity variations were 1.0 m / s, 1.5 m / s, and 2.0 m / s. Split-ratio was made in the range 25-70 %. The watercut in underflow were the variables measured. The experimental results show that the LLCC was able to separate water and oil and produced free water with concentration up to 98%. By increasing the value of the split-ratio, watercut in underflow increase and reached the optimum point. Optimal split-ratio observed is between 60 % and 70 % depend on the inlet oil volume fraction.

  8. Development of a liquid-fed water resistojet

    NASA Technical Reports Server (NTRS)

    Morren, W. Earl; Stone, James R.

    1988-01-01

    A concept for a forced-flow once-through water vaporizer for application to resistojet thrusters was evaluated as an element of a laboratory model thruster and tested to investigate its operating characteristics. The vaporizer design concept employs flow swirling to attach the liquid flow to the boiler chamber wall, providing for separation of the two liquid phases. This vaporizer was modified with a nozzle and a centrally-located heater to facilitate vaporization, superheating, and expansion of the propellant, allowing it to function as a resistojet. Performance was measured at thrust levels ranging from 170 to 360 mN and at power levels ranging from 443 to 192 W. Maximum measured specific impulse was 192 sec.

  9. Genomic organisation of the chicken ghrelin gene and its single nucleotide polymorphisms detected by denaturing high-performance liquid chromatography.

    PubMed

    Nie, Q; Zeng, H; Lei, M; Ishag, N A; Fang, M; Sun, B; Yang, G; Zhang, X

    2004-10-01

    (1) Ghrelin is a novel endogenous ligand for the growth hormone secretagogue receptor (GHS-R) and is expressed primarily in the stomach and hypothalamus with the probable function of stimulating GH secretion and food intake both in mammals and poultry. The complete sequences of ghrelin gene have been reported in humans and mice; however, that of chickens remains unclear. (2) Here, we report the complete sequence of chicken ghrelin gene (submitted to Genbank; accession number AY303688), which consists of 5 exons and 4 introns. As in mice, the first exon of chicken ghrelin gene does not encode any amino acid. (3) Scanning point mutations with denaturing high-performance liquid chromatography (DHPLC) using WAVE DNA Fragment Analysis Systems and confirmed with direct sequencing for polymerase chain reaction (PCR) products, we analysed the single nucleotide polymorphisms (SNPs) in the entire gene of chicken ghrelin. (4) Results showed that there were 19 SNPs in chicken ghrelin gene, and most of these SNPs were scattered in the 4 introns. In these SNPs, one mutation in exon 5 (A2355G) led to the change of amino acid from glutamine to arginine (Gln 113 Arg): as a result a different ghrelin precursor instead of a mature peptide was produced. In addition, one SNP in 5'UTR (C223G) determined the presence or absence of a potential binding site of transcription factor serum response factor (SRF), which might affect the expression of chicken ghrelin gene. Some of the SNPs detected in the present study could be used in quantitative trait loci (QTL) mapping for growth characters in chickens. (5) Because one SNP is located in a polymorphic site of restriction enzyme PagI of intron 4, it was possible to design a PCR-RFLP procedure and analyse the diversity of 10 chicken populations. Results showed the allelic frequencies of C2100T differ among these breeds, however, no significant difference was observed between imported breeds and Chinese native ones, nor between egg layers and

  10. Liquid/liquid metal extraction: Phase diagram topology resulting from molecular interactions between extractant, ion, oil and water

    NASA Astrophysics Data System (ADS)

    Bauer, C.; Bauduin, P.; Dufrêche, J. F.; Zemb, T.; Diat, O.

    2012-11-01

    We consider the class of surfactants called "extractants" since they specifically interact with some cations and are used in liquid-liquid separation processes. We review here features of water-poor reverse micelles in water/oil/ extractant systems as determined by combined structural studies including small angle scattering techniques on absolute scale. Origins of instabilities, liquid-liquid separation as well as emulsification failure are detected. Phase diagrams contain the same multi-phase domains as classical microemulsions, but special unusual features appear due to the high spontaneous curvature directed towards the polar cores of aggregates as well as rigidity of the film made by extracting molecules.

  11. Ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction for the separation and determination of estrogens in water samples by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Zhang, Rui; Wang, Chuanliu; Yue, Qiaohong; Zhou, Tiecheng; Li, Na; Zhang, Hanqi; Hao, Xiaoke

    2014-11-01

    An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-α-estradiol, 17-β-estradiol-benzoate, and quinestrol in environmental water samples by high-performance liquid chromatography with fluorescence detection. 1-Hexyl-3-methylimidazolium tetrafluoroborate was applied as foaming agent in the foam flotation process and dispersive solvent in microextraction. The introduction of the ion-pairing and salting-out agent NH4 PF6 was beneficial to the improvement of recoveries for the hydrophobic ionic liquid phase and analytes. Parameters of the proposed method including concentration of 1-hexyl-3-methylimidazolium tetrafluoroborate, flow rate of carrier gas, floatation time, types and concentration of ionic liquids, salt concentration in samples, extraction time, and centrifugation time were evaluated. The recoveries were between 98 and 105% with relative standard deviations lower than 7% for lake water and well water samples. The isolation of the target compounds from the water was found to be efficient, and the enrichment factors ranged from 4445 to 4632. This developing method is free of volatile organic solvents compared with regular extraction. Based on the unique properties of ionic liquids, the application of foam floatation, and dispersive liquid-liquid microextraction was widened. PMID:25146581

  12. Gas hydrate inhibition by perturbation of liquid water structure

    NASA Astrophysics Data System (ADS)

    Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Lee, Kun-Hong

    2015-06-01

    Natural gas hydrates are icy crystalline materials that contain hydrocarbons, which are the primary energy source for this civilization. The abundance of naturally occurring gas hydrates leads to a growing interest in exploitation. Despite their potential as energy resources and in industrial applications, there is insufficient understanding of hydrate kinetics, which hinders the utilization of these invaluable resources. Perturbation of liquid water structure by solutes has been proposed to be a key process in hydrate inhibition, but this hypothesis remains unproven. Here, we report the direct observation of the perturbation of the liquid water structure induced by amino acids using polarized Raman spectroscopy, and its influence on gas hydrate nucleation and growth kinetics. Amino acids with hydrophilic and/or electrically charged side chains disrupted the water structure and thus provided effective hydrate inhibition. The strong correlation between the extent of perturbation by amino acids and their inhibition performance constitutes convincing evidence for the perturbation inhibition mechanism. The present findings bring the practical applications of gas hydrates significantly closer, and provide a new perspective on the freezing and melting phenomena of naturally occurring gas hydrates.

  13. Gas hydrate inhibition by perturbation of liquid water structure.

    PubMed

    Sa, Jeong-Hoon; Kwak, Gye-Hoon; Han, Kunwoo; Ahn, Docheon; Lee, Kun-Hong

    2015-01-01

    Natural gas hydrates are icy crystalline materials that contain hydrocarbons, which are the primary energy source for this civilization. The abundance of naturally occurring gas hydrates leads to a growing interest in exploitation. Despite their potential as energy resources and in industrial applications, there is insufficient understanding of hydrate kinetics, which hinders the utilization of these invaluable resources. Perturbation of liquid water structure by solutes has been proposed to be a key process in hydrate inhibition, but this hypothesis remains unproven. Here, we report the direct observation of the perturbation of the liquid water structure induced by amino acids using polarized Raman spectroscopy, and its influence on gas hydrate nucleation and growth kinetics. Amino acids with hydrophilic and/or electrically charged side chains disrupted the water structure and thus provided effective hydrate inhibition. The strong correlation between the extent of perturbation by amino acids and their inhibition performance constitutes convincing evidence for the perturbation inhibition mechanism. The present findings bring the practical applications of gas hydrates significantly closer, and provide a new perspective on the freezing and melting phenomena of naturally occurring gas hydrates. PMID:26082291

  14. Liquid-liquid equilibria of the ternary system water + acetic acid + 1-hexanol

    SciTech Connect

    Fahim, M.A.; Al-Muhtaseb, S.A.; Al-Nashef, I.M.

    1997-01-01

    The recovery of organic acids from dilute solutions resulting from fermentation processes is important and many solvents have been tried to improve such recovery. Liquid-liquid equilibria for the ternary system water + acetic acid + 1-hexanol were measured over a temperature range of (288 to 323) K. The results were used to estimate the interaction parameters between each of the three compounds for the NRTL and UNIQUAC models and between each of the main groups of H{sub 2}O, CH{sub 2} (paraffinic CH{sub 2}), OH, and COOH for the UNIFAC model as a function of temperature. The estimated interaction parameters were successfully used to predict the equilibrium compositions by the three models. The NRTL equation was the most accurate model in correlating the overall equilibrium compositions of the studied system. The UNIQUAC and UNIFAC models satisfactorily predicted the equilibrium compositions.

  15. Homogeneous liquid-liquid solvent extraction. [Propylene carbonate-water system

    SciTech Connect

    Ting, C.S.; Williams, E.T.; Finston, H.L.

    1980-01-01

    This investigation was undertaken to extend the technique of homogeneous liquid-liquid solvent extraction into propylene carbonate. The mutual solubilities of propylene carbonate in water and vice-versa are shown in the phase diagram. The extraction of a variety of monodentate and bidentate ligand complexes with Fe(III) as a function of ligand concentration and pH were investigated. The monodentate ligands studied include, thiocyanate, chloride, bromide, benzoate, and bathophenanthrolines. The bidentate ligands studied include the various ..beta..-diketones, 8-quinolinol, and also cupferron which was studied under normal conditions, i.e., not under conditions of homogeneous extraction. The homogeneous extraction proved effective for a variety of chelate complexes and ion association complexes of iron giving, in all cases, very rapid extraction as compared with the slow rate of conventional extraction methods.

  16. Investigation of a liquid-fed water resistojet plume

    NASA Technical Reports Server (NTRS)

    Manzella, D. H.; Carney, L. M.

    1989-01-01

    Measurements of mass flux and flow angle were taken throughout the forward flow region of the exhaust of a liquid-fed water resistojet using a quartz crystal microbalance (QCM). The resistojet operated at a mass flow rate of 0.1 g/s with a power input of 330 Watts. Measured values were compared to theoretical predictions obtained by employing a source flow approximation. Excellent agreement between predicted and measured mass flux values was attained; however, this agreement was highly dependent on knowledge of nozzle flow conditions. Measurements of the temperature at which the exhaust condensed on the QCM were obtained as a function of incident mass flux.

  17. An accurate and simple quantum model for liquid water.

    PubMed

    Paesani, Francesco; Zhang, Wei; Case, David A; Cheatham, Thomas E; Voth, Gregory A

    2006-11-14

    The path-integral molecular dynamics and centroid molecular dynamics methods have been applied to investigate the behavior of liquid water at ambient conditions starting from a recently developed simple point charge/flexible (SPC/Fw) model. Several quantum structural, thermodynamic, and dynamical properties have been computed and compared to the corresponding classical values, as well as to the available experimental data. The path-integral molecular dynamics simulations show that the inclusion of quantum effects results in a less structured liquid with a reduced amount of hydrogen bonding in comparison to its classical analog. The nuclear quantization also leads to a smaller dielectric constant and a larger diffusion coefficient relative to the corresponding classical values. Collective and single molecule time correlation functions show a faster decay than their classical counterparts. Good agreement with the experimental measurements in the low-frequency region is obtained for the quantum infrared spectrum, which also shows a higher intensity and a redshift relative to its classical analog. A modification of the original parametrization of the SPC/Fw model is suggested and tested in order to construct an accurate quantum model, called q-SPC/Fw, for liquid water. The quantum results for several thermodynamic and dynamical properties computed with the new model are shown to be in a significantly better agreement with the experimental data. Finally, a force-matching approach was applied to the q-SPC/Fw model to derive an effective quantum force field for liquid water in which the effects due to the nuclear quantization are explicitly distinguished from those due to the underlying molecular interactions. Thermodynamic and dynamical properties computed using standard classical simulations with this effective quantum potential are found in excellent agreement with those obtained from significantly more computationally demanding full centroid molecular dynamics

  18. The structural origin of anomalous properties of liquid water

    PubMed Central

    Nilsson, Anders; Pettersson, Lars G. M.

    2015-01-01

    Water is unique in its number of unusual, often called anomalous, properties. When hot it is a normal simple liquid; however, close to ambient temperatures properties, such as the compressibility, begin to deviate and do so increasingly on further cooling. Clearly, these emerging properties are connected to its ability to form up to four well-defined hydrogen bonds allowing for different local structural arrangements. A wealth of new data from various experiments and simulations has recently become available. When taken together they point to a heterogeneous picture with fluctuations between two classes of local structural environments developing on temperature-dependent length scales. PMID:26643439

  19. Application of liquid-liquid-liquid microextraction and high-performance liquid-chromatography for the determination of sulfonamides in water.

    PubMed

    Lin, Che-Yi; Huang, Shang-Da

    2008-03-31

    This work presents a novel liquid-liquid-liquid microextraction (LLLME) technique for the extraction of sulfonamides from aqueous systems; it combines with high-performance liquid-chromatography-ultraviolet absorbance detection (HPLC/UV). In this experiment the sulfonamides were successively extracted from a donor phase (i.e., a water sample) into several microliters of an organic phase and then from the organic phase into an acceptor phase (i.e., an aqueous extract) by LLLME. The following separation and quantitative analyses were performed using HPLC/UV with 265 nm detection. Extraction condition such as solvent identity, agitation, extraction time, acceptor phase NaOH concentration, donor phase pH, and salt addition were optimized. Relative standard deviation (RSD, 2.6-5.3%), coefficient of estimation (R2, 0.9972-0.9999), and method detection limit (MDL, 0.11-0.77 ng mL(-1)) were achieved under the selected conditions. The proposed method was successfully applied to the analyses of three practical water samples and the relative recoveries of sulfonamides from the spiked water samples were in the range of 86.2-108.7%. The proposed method also confirms microextraction to be robust to monitoring trace levels of sulfacetamide, sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamonomethoxine, sulfamethoxazole, and sulfaquinoxaline in aqueous samples. PMID:18331856

  20. Interplay of the Glass Transition and the Liquid-Liquid Phase Transition in Water

    PubMed Central

    Giovambattista, Nicolas; Loerting, Thomas; Lukanov, Boris R.; Starr, Francis W.

    2012-01-01

    Water has multiple glassy states, often called amorphous ices. Low-density (LDA) and high-density (HDA) amorphous ice are separated by a dramatic, first-order like phase transition. It has been argued that the LDA-HDA transformation connects to a first-order liquid-liquid phase transition (LLPT) above the glass transition temperature Tg. Direct experimental evidence of the LLPT is challenging to obtain, since the LLPT occurs at conditions where water rapidly crystallizes. In this work, we explore the implications of a LLPT on the pressure dependence of Tg(P) for LDA and HDA by performing computer simulations of two water models – one with a LLPT, and one without. In the absence of a LLPT, Tg(P) for all glasses nearly coincide. When there is a LLPT, different glasses exhibit dramatically different Tg(P) which are directly linked with the LLPT. Available experimental data for Tg(P) are only consistent with the scenario including a LLPT. PMID:22550566

  1. Lake morphometry and resource polymorphism determine niche segregation between cool- and cold-water-adapted fish.

    PubMed

    Hayden, Brian; Harrod, Chris; Kahilaineni, Kimmo K

    2014-02-01

    Climate change is increasing ambient temperatures in Arctic and subarctic regions, facilitating latitudinal range expansions of freshwater fishes adapted to warmer water temperatures. The relative roles of resource availability and interspecific interactions between resident and invading species in determining the outcomes of such expansions has not been adequately evaluated. Ecological interactions between a cool-water adapted fish, the perch (Perca fluviatilis), and the cold-water adapted European whitefish (Coregonus lavaretus), were studied in both shallow and deep lakes with fish communities dominated by (1) monomorphic whitefish, (2) monomorphic whitefish and perch, and (3) polymorphic whitefish and perch. A combination of stomach content, stable-isotope, and invertebrate prey availability data were used to identify resource use and niche overlap among perch, the trophic generalist large sparsely rakered (LSR) whitefish morph, and the pelagic specialist densely rakered (DR) whitefish morph in 10 subarctic lakes at the contemporary distribution limit of perch in northern Scandinavia. Perch utilized its putative preferred littoral niche in all lakes. LSR whitefish utilized both littoral and pelagic resources in monomorphic whitefish-dominated lakes. When found in sympatry with perch, LSR whitefish exclusively utilized pelagic prey in deep lakes, but displayed niche overlap with perch in shallow littoral lakes. DR whitefish was a specialist zooplanktivore, relegating LSR whitefish from pelagic habitats, leading to an increase in niche overlap between LSR whitefish and perch in deep lakes. Our results highlight how resource availability (lake depth and fish community) governs ecological interactions between native and invading species, leading to different outcomes even at the same latitudes. These findings suggest that lake morphometry and fish community structure data should be included in bioclimate envelope-based models of species distribution shifts

  2. Gas and liquid measurements in air-water bubbly flows

    SciTech Connect

    Zhou, X.; Doup, B.; Sun, X.

    2012-07-01

    Local measurements of gas- and liquid-phase flow parameters are conducted in an air-water two-phase flow loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The gas-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, bubble velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)

  3. Tunable shape transformation of freezing liquid water marbles.

    PubMed

    Zang, Duyang; Lin, Kejun; Wang, Wenkai; Gu, Yaxi; Zhang, Yongjian; Geng, Xingguo; Binks, Bernard P

    2014-03-01

    Liquid water marbles coated with fumed silica nanoparticles exhibit various shape transformations upon freezing which are dependent on the hydrophobicity of the nanoparticles. The shape can be recovered during re-melting. For marbles coated with the most hydrophobic particles, a vertically prolonged morphology with a pointed protrusion on the top is formed on freezing. For marbles coated with less hydrophobic particles, a lateral expanded flying saucer-shaped morphology is formed. The different responses to freezing result from the different heterogeneous nucleation sites owing to the different positions of the particles at the air-water interface. If the particles are more immersed in water, ice embryos tend to form in the concave cavities between the particles. The volume expansion of water caused by freezing and continuous nucleation lead to continuous lateral stretching of the particle network coating the droplet surface and ultimately to the horizontally inflated shape of the marble. If the particles are more exposed to air, nucleation occurs on the convex surface of the particles, similar to that of a bare water droplet on a hydrophobic substrate. PMID:24651262

  4. Innovative Strategy on Hydrogen Evolution Reaction Utilizing Activated Liquid Water

    PubMed Central

    Hwang, Bing-Joe; Chen, Hsiao-Chien; Mai, Fu-Der; Tsai, Hui-Yen; Yang, Chih-Ping; Rick, John; Liu, Yu-Chuan

    2015-01-01

    Splitting water for hydrogen production using light, or electrical energy, is the most developed ‘green technique’. For increasing efficiency in hydrogen production, currently, the most exciting and thriving strategies are focused on efficient and inexpensive catalysts. Here, we report an innovative idea for efficient hydrogen evolution reaction (HER) utilizing plasmon-activated liquid water with reduced hydrogen-bonded structure by hot electron transfer. This strategy is effective for all HERs in acidic, basic and neutral systems, photocatalytic system with a g-C3N4 (graphite carbon nitride) electrode, as well as in an inert system with an ITO (indium tin oxide) electrode. Compared to deionized water, the efficiency of HER increases by 48% based on activated water ex situ on a Pt electrode. Increase in energy efficiency from activated water is 18% at a specific current yield of −20 mA in situ on a nanoscale-granulated Au electrode. Moreover, the onset potential of −0.023 V vs RHE was very close to the thermodynamic potential of the HER (0 V). The measured current density at the corresponding overpotential for HER in an acidic system was higher than any data previously reported in the literature. This approach establishes a new vista in clean green energy production. PMID:26541371

  5. Innovative Strategy on Hydrogen Evolution Reaction Utilizing Activated Liquid Water.

    PubMed

    Hwang, Bing-Joe; Chen, Hsiao-Chien; Mai, Fu-Der; Tsai, Hui-Yen; Yang, Chih-Ping; Rick, John; Liu, Yu-Chuan

    2015-01-01

    Splitting water for hydrogen production using light, or electrical energy, is the most developed 'green technique'. For increasing efficiency in hydrogen production, currently, the most exciting and thriving strategies are focused on efficient and inexpensive catalysts. Here, we report an innovative idea for efficient hydrogen evolution reaction (HER) utilizing plasmon-activated liquid water with reduced hydrogen-bonded structure by hot electron transfer. This strategy is effective for all HERs in acidic, basic and neutral systems, photocatalytic system with a g-C3N4 (graphite carbon nitride) electrode, as well as in an inert system with an ITO (indium tin oxide) electrode. Compared to deionized water, the efficiency of HER increases by 48% based on activated water ex situ on a Pt electrode. Increase in energy efficiency from activated water is 18% at a specific current yield of -20 mA in situ on a nanoscale-granulated Au electrode. Moreover, the onset potential of -0.023 V vs RHE was very close to the thermodynamic potential of the HER (0 V). The measured current density at the corresponding overpotential for HER in an acidic system was higher than any data previously reported in the literature. This approach establishes a new vista in clean green energy production. PMID:26541371

  6. Innovative Strategy on Hydrogen Evolution Reaction Utilizing Activated Liquid Water

    NASA Astrophysics Data System (ADS)

    Hwang, Bing-Joe; Chen, Hsiao-Chien; Mai, Fu-Der; Tsai, Hui-Yen; Yang, Chih-Ping; Rick, John; Liu, Yu-Chuan

    2015-11-01

    Splitting water for hydrogen production using light, or electrical energy, is the most developed ‘green technique’. For increasing efficiency in hydrogen production, currently, the most exciting and thriving strategies are focused on efficient and inexpensive catalysts. Here, we report an innovative idea for efficient hydrogen evolution reaction (HER) utilizing plasmon-activated liquid water with reduced hydrogen-bonded structure by hot electron transfer. This strategy is effective for all HERs in acidic, basic and neutral systems, photocatalytic system with a g-C3N4 (graphite carbon nitride) electrode, as well as in an inert system with an ITO (indium tin oxide) electrode. Compared to deionized water, the efficiency of HER increases by 48% based on activated water ex situ on a Pt electrode. Increase in energy efficiency from activated water is 18% at a specific current yield of -20 mA in situ on a nanoscale-granulated Au electrode. Moreover, the onset potential of -0.023 V vs RHE was very close to the thermodynamic potential of the HER (0 V). The measured current density at the corresponding overpotential for HER in an acidic system was higher than any data previously reported in the literature. This approach establishes a new vista in clean green energy production.

  7. Distribution of binding energies of a water molecule in the water liquid-vapor interface

    SciTech Connect

    Chempath, Shaji; Pratt, Lawrence R

    2008-01-01

    Distributions of binding energies of a water molecule in the water liquid-vapor interface are obtained on the basis of molecular simulation with the SPC/E model of water. These binding energies together with the observed interfacial density profile are used to test a minimally conditioned Gaussian quasi-chemical statistical thermodynamic theory. Binding energy distributions for water molecules in that interfacial region clearly exhibit a composite structure. A minimally conditioned Gaussian quasi-chemical model that is accurate for the free energy of bulk liquid water breaks down for water molecules in the liquid-vapor interfacial region. This breakdown is associated with the fact that this minimally conditioned Gaussian model would be inaccurate for the statistical thermodynamics of a dilute gas. Aggressive conditioning greatly improves the performance of that Gaussian quasi-chemical model. The analogy between the Gaussian quasi-chemical model and dielectric models of hydration free energies suggests that naive dielectric models without the conditioning features of quasi-chemical theory will be unreliable for these interfacial problems. Multi-Gaussian models that address the composite nature of the binding energy distributions observed in the interfacial region might provide a mechanism for correcting dielectric models for practical applications.

  8. Hot electron dominated rapid transverse ionization growth in liquid water.

    PubMed

    Brown, Michael S; Erickson, Thomas; Frische, Kyle; Roquemore, William M

    2011-06-20

    Pump/probe optical-transmission measurements are used to monitor in space and time the ionization of a liquid column of water following impact of an 800-nm, 45-fs pump pulse. The pump pulse strikes the 53-μm-diameter column normal to its axis with intensities up to 2 × 10(15) W/cm2. After the initial photoinization and for probe delay times < 500 fs, the neutral water surrounding the beam is rapidly ionized in the transverse direction, presumably by hot electrons with initial velocities of 0.55 times the speed of light (relativistic kinetic energy of ~100 keV). Such velocities are unusual for condensed-matter excitation at the stated laser intensities. PMID:21716461

  9. An SCC-DFTB Repulsive Potential for Various ZnO Polymorphs and the ZnO–Water System

    PubMed Central

    2013-01-01

    We have developed an efficient scheme for the generation of accurate repulsive potentials for self-consistent charge density-functional-based tight-binding calculations, which involves energy-volume scans of bulk polymorphs with different coordination numbers. The scheme was used to generate an optimized parameter set for various ZnO polymorphs. The new potential was subsequently tested for ZnO bulk, surface, and nanowire systems as well as for water adsorption on the low-index wurtzite (101̅0) and (112̅0) surfaces. By comparison to results obtained at the density functional level of theory, we show that the newly generated repulsive potential is highly transferable and capable of capturing most of the relevant chemistry of ZnO and the ZnO/water interface. PMID:23991228

  10. The structure of liquid water beyond the first hydration shell.

    PubMed

    Henao, Andrés; Busch, Sebastian; Guàrdia, Elvira; Tamarit, Josep Lluis; Pardo, Luis Carlos

    2016-07-28

    To date there is a general consensus on the structure of the first coordination shells of liquid water, namely tetrahedral short range order of molecules. In contrast, little is known about the structure at longer distances and the influence of the tetrahedral molecular arrangement of the first shells on the order at these length scales. An expansion of the distance dependent excess entropy is used in this contribution to find out which molecular arrangements are important at each distance range. This was done by splitting the excess entropy into two parts: one connected to the relative position of two molecules and the other one related to their relative orientation. A transition between two previously unknown regimes in liquid water is identified at a distance of about ∼6 Å: from a predominantly orientational order at shorter distances to a regime at larger distances of up to ∼9 Å where the order is predominantly positional and molecules are distributed with the same tetrahedral symmetry as the very first molecules. PMID:27377988

  11. Stability of amorphous silica-alumina in hot liquid water.

    PubMed

    Hahn, Maximilian W; Copeland, John R; van Pelt, Adam H; Sievers, Carsten

    2013-12-01

    Herein, the hydrothermal stability of amorphous silica-alumina (ASA) is investigated under conditions relevant for the catalytic conversion of biomass, namely in liquid water at 200 °C. The hydrothermal stability of ASA is much higher than that of pure silica or alumina. Interestingly, the synthetic procedure used plays a major role in its resultant stability: ASA prepared by cogelation (CG) lost its microporous structure, owing to hydrolysis of the siloxane bonds, but the resulting mesoporous material still had a considerable surface area. ASA prepared by deposition precipitation (DP) contained a silicon-rich core and an aluminum-rich shell. In hot liquid water, the latter structure was transformed into a layer of amorphous boehmite, which protected the particle from further hydrolysis. The surface area showed relatively minor changes during the transformation. Independent of the synthetic method used, the ASAs retained a considerable concentration of acid sites. The concentration of acid sites qualitatively followed the changes in surface area, but the changes were less pronounced. The performance of different ASAs for the hydrolysis of cellobiose into glucose is compared. PMID:24124062

  12. Stopping power of liquid water for low-energy electrons

    SciTech Connect

    Ashley, J.C.

    1982-01-01

    The dielectric function epsilon(q,..omega..) for liquid water is determined from an insulator model with parameters fixed by available optical data. Ionization of the oxygen K shell is described by generalized oscillator strengths. This model dielectric function is used to calculate the stopping power of liquid water for electrons with energies from 10 eV to 10 keV. The results agree well in the common energy range with an existing tabulation for 256 eV less than or equal to E less than or equal to 10.2 MeV and with Bethe-theory predictions down to 200 eV. The peak in stopping power at approx.25% lower than the predictions of R. H. Ritchie, R. N. Hamm, J.E. Turner, and H. A. Wright (in Proceedings, Sixth Symposium on Microdosimetry, Brussels, Belgium (J. Booz and H. G. Ebert, Eds.), pp. 345-354, Commission of the European Communities, Harwood, London, 1978 (EUR 6064 d-e-f)).

  13. ETV REPORT AND VERIFICATION STATEMENT; EVALUATION OF LOBO LIQUIDS RINSE WATER RECOVERY SYSTEM

    EPA Science Inventory

    The Lobo Liquids Rinse Water Recovery System (Lobo Liquids system) was tested, under actual production conditions, processing metal finishing wastewater, at Gull Industries in Houston, Texas. The verification test evaluated the ability of the ion exchange (IX) treatment system t...

  14. Computing the melting point and thermodynamic stability of the orthorhombic and monoclinic crystalline polymorphs of the ionic liquid 1-n-butyl-3-methylimidazolium chloride

    NASA Astrophysics Data System (ADS)

    Jayaraman, Saivenkataraman; Maginn, Edward J.

    2007-12-01

    The melting point, enthalpy of fusion, and thermodynamic stability of two crystal polymorphs of the ionic liquid 1-n-butyl-3-methylimidazolium chloride are calculated using a thermodynamic integration-based atomistic simulation method. The computed melting point of the orthorhombic phase ranges from 365 to 369 K, depending on the classical force field used. This compares reasonably well with the experimental values, which range from 337 to 339 K. The computed enthalpy of fusion ranges from 19 to 29 kJ/mol, compared to the experimental values of 18.5-21.5 kJ/mol. Only one of the two force fields evaluated in this work yielded a stable monoclinic phase, despite the fact that both give accurate liquid state densities. The computed melting point of the monoclinic polymorph was found to be 373 K, which is somewhat higher than the experimental range of 318-340 K. The computed enthalpy of fusion was 23 kJ/mol, which is also higher than the experimental value of 9.3-14.5 kJ/mol. The simulations predict that the monoclinic form is more stable than the orthorhombic form at low temperature, in agreement with one set of experiments but in conflict with another. The difference in free energy between the two polymorphs is very small, due to the fact that a single trans-gauche conformational difference in an alkyl sidechain distinguishes the two structures. As a result, it is very difficult to construct simple classical force fields that are accurate enough to definitively predict which polymorph is most stable. A liquid phase analysis of the probability distribution of the dihedral angles in the alkyl chain indicates that less than half of the dihedral angles are in the gauche-trans configuration that is adopted in the orthorhombic crystal. The low melting point and glass forming tendency of this ionic liquid is likely due to the energy barrier for conversion of the remaining dihedral angles into the gauche-trans state. The simulation procedure used to perform the melting point

  15. Liquid state theories for the structure of water

    NASA Astrophysics Data System (ADS)

    Reddy, Govardhan; Lawrence, C. P.; Skinner, J. L.; Yethiraj, Arun

    2003-12-01

    Liquid state theories are investigated for the local structure of the simple point charge (SPC) and a modified SPC (MSPC) model of water. The latter model includes a van der Waals repulsion between the oxygen (O) and hydrogen (H) atoms, which is necessary for the implementation of some integral equation theories. Two integral equation theories, the reference interaction site model (RISM) and the diagrammatically proper Chandler-Silbey-Ladanyi (CSL) theory, are tested by comparison with simulations of the MSPC model (neither theory converges for the SPC model when the hypernetted chain closure is used). The RISM theory is in reasonable agreement with simulations, and is more accurate than the CSL theory. A density functional theory (DFT) is investigated, which treats the ideal gas functional exactly and uses a truncated expansion for the excess free energy functional. The DFT is in excellent agreement with simulations for the structure of the MSPC water model at all temperatures studied, and for the structure of the SPC water model at high temperatures. At room temperature, the DFT is in good agreement with simulations (of SPC water) for gHH(r) and gOH(r), but misses the location of the second peak in gOO(r). We attribute this deficiency to the importance of three-body correlations that are not properly incorporated in the theory.

  16. Relationship between optical extinction and liquid water content in fogs

    NASA Astrophysics Data System (ADS)

    Klein, C.; Dabas, A.

    2014-05-01

    Studies carried out in the late 1970s suggest that a simple linear relationship exists in practice between the optical extinction in the thermal IR and the liquid water content (LWC) in fogs. Such a relationship opens the possibility to monitor the vertical profile of the LWC in fogs with a rather simple backscatter lidar. Little is known on how the LWC varies as a function of height and during the fog life cycle, so the new measurement technique would help understand fog physics and provide valuable data for improving the quality of fog forecasts. In this paper, the validity of the linear relationship is revisited in the light of recent observations of fog droplet size distributions measured with a combination of sensors covering a large range of droplet radii. In particular, large droplets (radius above 15 μm) are now detected, which was not the case in the late 1970s. The results confirm that the linear relationship still holds, at least for the mostly radiative fogs observed during the campaign. The impact of the precise value of the real and imaginary parts of the refractive index on the coefficient of the linear relationship is also studied. The usual practice considers that droplets are made of pure water. This assumption is probably valid for big drops, but it may be questioned for small ones since droplets are formed from condensation nuclei of highly variable chemical composition. The study suggests that the precise nature of condensation nuclei will primarily affect rather light fogs with small droplets and light liquid water contents.

  17. Temporal changes in endmember abundances, liquid water and water vapor over vegetation at Jasper Ridge

    NASA Technical Reports Server (NTRS)

    Roberts, Dar A.; Green, Robert O.; Sabol, Donald E.; Adams, John B.

    1993-01-01

    Imaging spectrometry offers a new way of deriving ecological information about vegetation communities from remote sensing. Applications include derivation of canopy chemistry, measurement of column atmospheric water vapor and liquid water, improved detectability of materials, more accurate estimation of green vegetation cover and discrimination of spectrally distinct green leaf, non-photosynthetic vegetation (NPV: litter, wood, bark, etc.) and shade spectra associated with different vegetation communities. Much of our emphasis has been on interpreting Airborne Visible/Infrared Imaging Spectrometry (AVIRIS) data spectral mixtures. Two approaches have been used, simple models, where the data are treated as a mixture of 3 to 4 laboratory/field measured spectra, known as reference endmembers (EM's), applied uniformly to the whole image, to more complex models where both the number of EM's and the types of EM's vary on a per-pixel basis. Where simple models are applied, materials, such as NPV, which are spectrally similar to soils, can be discriminated on the basis of residual spectra. One key aspect is that the data are calibrated to reflectance and modeled as mixtures of reference EM's, permitting temporal comparison of EM fractions, independent of scene location or data type. In previous studies the calibration was performed using a modified-empirical line calibration, assuming a uniform atmosphere across the scene. In this study, a Modtran-based calibration approach was used to map liquid water and atmospheric water vapor and retrieve surface reflectance from three AVIRIS scenes acquired in 1992 over the Jasper Ridge Biological Preserve. The data were acquired on June 2nd, September 4th and October 6th. Reflectance images were analyzed as spectral mixtures of reference EM's using a simple 4 EM model. Atmospheric water vapor derived from Modtran was compared to elevation, and community type. Liquid water was compare to the abundance of NPV, Shade and Green Vegetation

  18. LIQUID AND GAS CHROMATOGRAPHIC ANALYSIS OF DIETHYL PHTHALATE IN WATER AND SEDIMENT

    EPA Science Inventory

    Diethyl phthalate was determined in water and sediment by high performance liquid chromatography (HPLC) and in water by gas-liquid chromatography with electron capture detection (GLC-ECD). Water samples were extracted with hexane, using a high-speed homogenizer-ultrasonic apparat...

  19. Atom Pair Distribution Functions of Liquid Water at 25circC from Neutron Diffraction

    NASA Astrophysics Data System (ADS)

    Narten, A. H.; Thiessen, W. E.; Blum, L.

    1982-09-01

    The structure of liquid water is described by three atom pair distribution functions gOO(r), gOH(r), and gHH(r). These functions have now been derived from neutron diffraction data on four mixtures of light and heavy water. They will provide a crucial and sensitive test for proposed models of liquid water.

  20. Influence of liquid water and water vapor on antimisting kerosene (AMK)

    NASA Technical Reports Server (NTRS)

    Yavrouian, A. H.; Sarolouki, M.; Sarohia, V.

    1983-01-01

    Experiments have been performed to evaluate the compatibility of liquid water and water vapor with antimisting kerosenes (AMK) containing polymer additive FM-9 developed by Imperial Chemical Industries. This effort consists of the determination of water solubility in AMK, influence of water on restoration (degradation) of AMK, and effect of water on standard AMK quality control methods. The principal conclusions of this investigation are: (1) the uptake of water in AMK critically depends upon the degree of agitation and can be as high as 1300 ppm at 20 C, (2) more than 250 to 300 ppm of water in AMK causes an insoluble second phase to form. The amount of this second phase depends on fuel temperature, agitation, degree of restoration (degradation) and the water content of the fuel, (3) laboratory scale experiments indicate precipitate formation when water vapor comes in contact with cold fuel surfaces at a much lower level of water (125 to 150 ppm), (4) precipitate formation is very pronounced in these experiments where humid air is percolated through a cold fuel (-20 C), (5) laboratory tests further indicate that water droplet settling time is markedly reduced in AMK as compared to jet A, (6) limited low temperature testing down to -30 C under laboratory conditions indicates the formation of stable, transparent gels.

  1. Simulated liquid water and visibility in stratiform boundary-layer clouds over sloping terrain

    SciTech Connect

    Tjernstroem, M. )

    1993-04-01

    The amount of liquid water in stratus clouds or fog is discussed from the point of view of estimating visibility variations in areas with complex terrain. The average vertical profile of liquid water from numerical simulations with a higher-order closure mesoscale model is examined, and runs with the model for moderately complex terrain are utilized to estimate the of low-level liquid water content variability and thus, indirectly, the variations in horizontal visibility along a slope. 37 refs., 11 figs.

  2. The oxygen isotope partition function ratio of water and the structure of liquid water

    USGS Publications Warehouse

    O'Neil, J.R.; Adami, L.H.

    1969-01-01

    By means of the CO2-equilibration technique, the temperature dependence and absolute values of the oxygen isotope partition function ratio of liquid water have been determined, often at 1?? intervals, from -2 to 85??. A linear relationship between In (Q2/Q1) (H2O) and T-1 was obtained that is explicable in terms of the Bigeleisen-Mayer theory of isotopic fractionation. The data are incompatible with conventional, multicomponent mixture models of water because liquid water behaves isotopically as a singly structured homogeneous substance over the entire temperature range studied. A two-species model of water is proposed in which approximately 30% of the hydrogen bonds in ice are broken on melting at 0?? and in which this per cent of monomer changes by only a small amount over the entire liquid range. Because of the high precision and the fundamental property determined, the isotopic fractionation technique is particularly well suited to the detection of thermal anomalies. No anomalies were observed and those previously reported are ascribed to under-estimates of experimental error.

  3. Water-mediated ion–ion interactions are enhanced at the water vapor–liquid interface

    PubMed Central

    Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

    2014-01-01

    There is overwhelming evidence that ions are present near the vapor–liquid interface of aqueous salt solutions. Charged groups can also be driven to interfaces by attaching them to hydrophobic moieties. Despite their importance in many self-assembly phenomena, how ion–ion interactions are affected by interfaces is not understood. We use molecular simulations to show that the effective forces between small ions change character dramatically near the water vapor–liquid interface. Specifically, the water-mediated attraction between oppositely charged ions is enhanced relative to that in bulk water. Further, the repulsion between like-charged ions is weaker than that expected from a continuum dielectric description and can even become attractive as the ions are drawn to the vapor side. We show that thermodynamics of ion association are governed by a delicate balance of ion hydration, interfacial tension, and restriction of capillary fluctuations at the interface, leading to nonintuitive phenomena, such as water-mediated like charge attraction. “Sticky” electrostatic interactions may have important consequences on biomolecular structure, assembly, and aggregation at soft liquid interfaces. We demonstrate this by studying an interfacially active model peptide that changes its structure from α-helical to a hairpin-turn–like one in response to charging of its ends. PMID:24889634

  4. Monte Carlo simulation of electron dynamics in liquid water

    NASA Astrophysics Data System (ADS)

    Huthmacher, Klaus; Herzwurm, André; Gnewuch, Michael; Ritter, Klaus; Rethfeld, Baerbel

    2015-07-01

    We present a stochastic model for the energy loss of low-energy electrons (<100 eV) in water in the liquid phase. More precisely, we treat the electrons as independent particles and are thus able to model the time evolution of the kinetic energy of a single electron as a so-called pure jump process. Free electrons are created due to irradiation of an extreme ultraviolet femtosecond laser pulse. In our model, free electrons may interact with water molecules via elastic scattering and impact ionization. Moreover, we present numerical results for the kinetic energy of electrons during and after laser irradiation. Furthermore, we distinguish between primary and secondary electrons, where the latter are created by impact ionization. The numerical results show that creation of secondary electrons due to impact ionization occurs almost entirely during laser irradiation. After irradiation, only a small amount of the laser pulse energy remains in the electron system, while the majority is stored in holes of water molecules.

  5. Assay of organic liquid contents in predominantly water-wet unconsolidated porous media

    NASA Astrophysics Data System (ADS)

    Cary, J. W.; McBride, J. F.; Simmons, C. S.

    1991-11-01

    Immiscible organic liquids may be extracted from moist soil or other hydrophilic porous media by shaking a suspension of water and soil in a glass jar with a piece of porous polyethylene. The water displaces the organic liquid from the predominantly hydrophilic sample and the hydrophobic polyethylene preferentially absorbs the organic liquid, excluding water unless there is a detergent associated with the organic. Because most soils have some hydrophobic surfaces, the extraction of organic liquids by displacement with water is not quite complete. A correction is therefore made in the assay method by including samples with known organic liquid content as controls. The amount of organic liquid not displaced from the control samples can also be used to indicate the extent of hydrophobic sites in predominantly water-wet porous media. Organic liquid extractions were made by using three soils and two organic liquids. The standard deviation among replicated extractions was 0.010 g organic liquid. By applying a correction to the mass of organic liquid recovered, the assay accuracy was ±0.001 g organic liquid/g soil with 20.0-g oven-dry soil samples. It is likely that this assay method could be scaled up and used as a remediation method for removing and recovering organic liquids from earth excavated from spill or leak sites.

  6. Onset of simple liquid behaviour in modified water models

    SciTech Connect

    Prasad, Saurav; Chakravarty, Charusita

    2014-04-28

    The transition to simple liquid behaviour is studied in a set of modified hybrid water models where the potential energy contribution of the Lennard-Jones dispersion-repulsion contribution is progressively enhanced relative to the electrostatic contribution. Characteristics of simple liquid behaviour that indicate the extent to which a given system can be mapped onto an inverse power law fluid are examined, including configurational energy-virial correlations, functional form of temperature dependence of the excess entropy along isochores, and thermodynamic and excess entropy scaling of diffusivities. As the Lennard-Jones contribution to the potential energy function increases, the strength of the configurational energy-virial correlations increases. The Rosenfeld-Tarazona temperature dependence of the excess entropy is found to hold for the range of state points studied here for all the hybrid models, regardless of the degree of correlating character. Thermodynamic scaling is found to hold for weakly polar fluids with a moderate degree of energy-virial correlations. Rosenfeld-scaling of transport properties is found not to be necessarily linked with the strength of energy-virial correlations but may hold for systems with poor thermodynamic scaling if diffusivities and excess entropies show correlated departures from the isomorph-invariant behaviour characteristic of approximate inverse power law fluids. The state-point dependence of the configurational energy-virial correlation coefficient and the implications for thermodynamic and excess entropy scalings are considered.

  7. Use of Spacecraft Data to Drive Regions on Mars where Liquid Water would be Stable

    NASA Technical Reports Server (NTRS)

    Lobitz, Brad; Wood, Byron L.; Averner, Maurice M.; McKay, Christopher P.; MacElroy, Robert D.

    2001-01-01

    Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter (MOLA) topography data we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40 degrees. The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia where 34% of the year liquid water would be stable if it was present. Locations of stability appear to correlate with the distribution of valley networks.

  8. Use of spacecraft data to derive regions on Mars where liquid water would be stable.

    PubMed

    Lobitz, B; Wood, B L; Averner, M M; McKay, C P

    2001-02-27

    Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter topography data, we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40 degrees. The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia, where 34% of the year liquid water would be stable if it were present. Locations of stability appear to correlate with the distribution of valley networks. PMID:11226204

  9. Use of spacecraft data to derive regions on Mars where liquid water would be stable

    PubMed Central

    Lobitz, Brad; Wood, Byron L.; Averner, Maurice M.; McKay, Christopher P.

    2001-01-01

    Combining Viking pressure and temperature data with Mars Orbital Laser Altimeter topography data, we have computed the fraction of the martian year during which pressure and temperature allow for liquid water to be stable on the martian surface. We find that liquid water would be stable within the Hellas and Argyre basin and over the northern lowlands equatorward of about 40°. The location with the maximum period of stable conditions for liquid water is in the southeastern portion of Utopia Planitia, where 34% of the year liquid water would be stable if it were present. Locations of stability appear to correlate with the distribution of valley networks. PMID:11226204

  10. Electrokinetic Hydrogen Generation from Liquid WaterMicrojets

    SciTech Connect

    Duffin, Andrew M.; Saykally, Richard J.

    2007-05-31

    We describe a method for generating molecular hydrogen directly from the charge separation effected via rapid flow of liquid water through a metal orifice, wherein the input energy is the hydrostatic pressure times the volume flow rate. Both electrokinetic currents and hydrogen production rates are shown to follow simple equations derived from the overlap of the fluid velocity gradient and the anisotropic charge distribution resulting from selective adsorption of hydroxide ions to the nozzle surface. Pressure-driven fluid flow shears away the charge balancing hydronium ions from the diffuse double layer and carries them out of the aperture. Downstream neutralization of the excess protons at a grounded target electrode produces gaseous hydrogen molecules. The hydrogen production efficiency is currently very low (ca. 10-6) for a single cylindrical jet, but can be improved with design changes.

  11. Conversion of lignocellulosics pretreated with liquid hot water to ethanol

    SciTech Connect

    Walsum, G.P. van; Laser, M.S.; Lynd, L.R.

    1996-12-31

    Lignocellulosic materials pretreated using liquid hot water (LHW) (220{degrees}C, 5 MPa, 120 s) were fermented to ethanol by batch simultaneous saccharification and fermentation (SSF) using Saccharomyces cerevisiae in the presence of Trichoderma reesei cellulose. SSF of sugarcane bagasse (as received), aspen chips (smallest dimension 3 mm), and mixed hardwood flour (-60 +70 mesh) resulted in 90% conversion to ethanol in 2-5 d at enzyme loadings of 15-30 FPU/g. In most cases, 90% of the final conversion was achieved within 75 h of inoculation. Comminution of the pretreated substrates did not affect the conversion to ethanol. The hydrolysate produced from the LHW pretreatment showed slight inhibition of batch growth of S. cerevisiae. Solids pretreated at a concentration of 100 g/L were as reactive as those pretreated at a lower concentration, provided that the temperature was maintained at 220{degrees}C. 51 refs., 3 figs., 4 tabs.

  12. Characterization and Modeling of a Water-based Liquid Scintillator

    SciTech Connect

    L. J. Bignell; Beznosko, D.; Diwan, M. V.; Hans, S.; Jaffe, D. E.; S. Kettell; Rosero, R.; Themann, H. W.; Viren, B.; Worcester, E.; Yeh, M.; Zhang, C.

    2015-12-15

    We characterised Water-based Liquid Scintillator (WbLS) using low energy protons, UV-VIS absorbance, and fluorescence spectroscopy. We have also developed and validated a simulation model that describes the behaviour of WbLS in our detector configurations for proton beam energies of 210 MeV, 475 MeV, and 2 GeV and for two WbLS compositions. These results have enabled us to estimate the light yield and ionisation quenching of WbLS, as well as to understand the influence of the wavelength shifting of Cherenkov light on our measurements. These results are relevant to the suitability of WbLS materials for next generation intensity frontier experiments.

  13. Detachment of Liquid-Water Droplets from Gas-Diffusion Layers

    SciTech Connect

    Das, Prodip K.; Grippin, Adam; Weber, Adam Z.

    2011-07-01

    A critical issue for optimal water management in proton-exchange-membrane fuel cells at lower temperatures is the removal of liquid water from the cell. This pathway is intimately linked with the phenomena of liquid-water droplet removal from surface of the gas-diffusion layer and into the flow channel. Thus, a good understanding of liquid-water transport and droplet growth and detachment from the gas-diffusion layer is critical. In this study, liquid-water droplet growth and detachment on the gas-diffusion layer surfaces are investigated experimentally to improve the understating of water transport through and removal from gas-diffusion layers. An experiment using a sliding-angle measurement is designed and used to quantify and directly measure the adhesion force for liquid-water droplets, and to understand the droplets? growth and detachment from the gas-diffusion layers.

  14. Cloud Liquid Water, Mean Droplet Radius and Number Density Measurements Using a Raman Lidar

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Melfi, S. Harvey

    1999-01-01

    A new technique for measuring cloud liquid water, mean droplet radius and droplet number density is outlined. The technique is based on simultaneously measuring Raman and Mie scattering from cloud liquid droplets using a Raman lidar. Laboratory experiments on liquid micro-spheres have shown that the intensity of Raman scattering is proportional to the amount of liquid present in the spheres. This fact is used as a constraint on calculated Mie intensity assuming a gamma function particle size distribution. The resulting retrieval technique is shown to give stable solutions with no false minima. It is tested using Raman lidar data where the liquid water signal was seen as an enhancement to the water vapor signal. The general relationship of retrieved average radius and number density is consistent with traditional cloud physics models. Sensitivity to the assumed maximum cloud liquid water amount and the water vapor mixing ratio calibration are tested. Improvements to the technique are suggested.

  15. Cloud liquid water, mean droplet radius, and number density measurements using a Raman lidar

    SciTech Connect

    Whiteman, David N.; Melfi, S. Harvey

    1999-12-27

    A new technique for measuring cloud liquid water, mean droplet radius, and droplet number density is outlined. The technique is based on simultaneously measuring Raman and Mie scattering from cloud liquid droplets using a Raman lidar. Laboratory experiments on liquid microspheres have shown that the intensity of Raman scattering is proportional to the amount of liquid present in the spheres. This fact is used as a constraint on calculated Mie intensity assuming a gamma function particle size distribution. The resulting retrieval technique is shown to give stable solutions with no false minima. It is tested using Raman lidar data where the liquid water signal was seen as an enhancement to the water vapor signal. The general relationship of retrieved average radius and number density is consistent with traditional cloud physics models. Sensitivity to the assumed maximum cloud liquid water amount and the water vapor mixing ratio calibration are tested. Improvements to the technique are suggested. (c) 1999 American Geophysical Union.

  16. The Effect of Xuefuzhuyu Oral Liquid on Aspirin Resistance and Its Association with rs5911, rs5787, and rs3842788 Gene Polymorphisms

    PubMed Central

    Xue, Mei; Yang, Lin; Kou, Na; Miao, Yu; Wang, Mingming; Zhao, Quanli; Ren, Junhua; Zhang, Shaoyan; Shi, Dazhuo; Chen, Keji

    2015-01-01

    Aspirin should be continued indefinitely in patients after interventional therapy, but 10% to 40% of patients experience recurrent vascular events despite adequate aspirin therapy, a condition known as aspirin resistance (AR). Xuefuzhuyu oral liquid, derived from the classic recipe Xuefuzhuyu decoction, has been well documented to inhibit platelet aggregation and to improve hemorheology. The aims of this study were to investigate the effects of Xuefuzhuyu oral liquid on AR in patients with chronic stable angina after percutaneous coronary intervention (PCI) and the possible genetic markers related to the drug response. 43 patients diagnosed as having aspirin resistance or semi-resistance were randomly divided into control and treatment groups after screening 207 stable CHD patients. Platelet aggregation rate was determined using turbidimetry. Three single nucleotide polymorphisms in COX-1 (rs5787, rs3842788) and GP IIb (rs5911) were genotyped in whole blood samples using ABI PRISM 7900 HT Fast Real-Time instrument and ABI PRISM 3730 DNA Sequencer. The results showed that Xuefuzhuyu oral liquid could effectively improve blood stasis syndrome and AR by inhibiting ADP-induced platelet aggregation and that patients with the rs5911 genetic variant exhibited better drug response upon treatment with Xuefuzhuyu oral liquid, which suggests Xuefuzhuyu oral liquid as a new possible drug for the prevention of AR. PMID:26495016

  17. DETERMINATION OF THE INSECT GROWTH REGULATOR METHOPRENE IN NATURAL WATERS BY CAPILLARY GAS-LIQUID CHROMATOGRAPHY

    EPA Science Inventory

    Residues of methoprene were measured in natural waters by capillary as liquid chromatography (GLG). Methoprene was extracted in the field by liquid-liquid partitioning with dichloromethane, transPorted to the laboratory, and extracted a second time with hexane. The extracts were ...

  18. Liquid Crystalline Properties of Amyloid Protein Fibers in Water

    NASA Astrophysics Data System (ADS)

    Mezzenga, Raffaele; Jung, Jin-Mi

    2010-03-01

    We have studied the liquid crystalline features of two colloidal systems consisting of food protein amyloid fibrils in water, obtained by heat-denaturation and aggregation of β-lactoglobulin, a globular dairy protein. The resulting fibrils, have a monodisperse cross section of about 4 nm and two groups of polydisperse contour lengths: (i) fibrils 1-10 μm long, showing semiflexible polyeletrolyte-like behaviour and (ii) rigid rods 100-200 nm long. In both systems, the fibers are highly charged (+5 e/nm) and stable in water at low ionic strength (0.01 M) and low pH (pH 2). The physical properties of these systems are studied using a polymer physics approach and phase diagrams of these two systems are obtained by changing concentration and pH. Both systems exhibit rich phase behaviours. Interestingly, the experimentally measured isotropic-nematic phase transition was found to occur at concentrations more than one order of magnitude lower than what expected based on Onsager theory. Experimental results are revisited in terms of the Flory theory developed for rigid polymers in solvent of varying conditions.

  19. Why does hydronium diffuse faster than hydroxide in liquid water?

    NASA Astrophysics Data System (ADS)

    Zheng, Lixin; Santra, Biswajit; Distasio, Robert; Klein, Michael; Car, Roberto; Wu, Xifan

    Experiments show that the hydronium ion (H3O+) diffuses much faster than the hydroxide ion (OH-) in liquid water. ab initio molecular dynamics (AIMD) simulations correctly associated the diffusion mechanism to proton transfer (PT) but have been unable so far to clearly identify the reason for the faster diffusion of hydronium compared to hydroxide, as the diffusion rate was found to depend sensitively on the adopted functional approximation. We carried out AIMD simulations of the solvated water ions using a van der Waals (vdW) inclusive PBE0 hybrid density functional. It is found that not only hydronium diffuses faster than hydroxide but also the absolute rates agree with experiment. The fast diffusion of H3O+ occurs via concerted PT that enables the ion to jump across several H-bonded molecules in successful transfer events; in contrast, such concerted motion is significantly hindered in OH- where the ion is easily trapped in a hyper-coordination configuration (a local solvation structure that forbids PT). As a result multiple PT events are rare and the diffusion of OH- is significantly slowed down. Such a clear difference between the two ions results from the combined effect of vdW interactions and self-interaction correction. Doe SciDac: DE-SC0008626 and DE-SC0008726.

  20. Direct determination of chlorophenols in water samples through ultrasound-assisted hollow fiber liquid-liquid-liquid microextraction on-line coupled with high-performance liquid chromatography.

    PubMed

    Chao, Yu-Ying; Tu, Yi-Ming; Jian, Zhi-Xuan; Wang, Hsaio-Wen; Huang, Yeou-Lih

    2013-01-01

    In this study we on-line coupled hollow fiber liquid-liquid-liquid microextraction (HF-LLLME), assisted by an ultrasonic probe, with high-performance liquid chromatography (HPLC). In this approach, the target analytes - 2-chlorophenol (2-CP), 3-chlorophenol (3-CP), 2,6-dichlorophenol (2,6-DCP), and 3,4-dichlorophenol (3,4-DCP) - were extracted into a hollow fiber (HF) supported liquid membrane (SLM) and then back-extracted into the acceptor solution in the lumen of the HF. Next, the acceptor solution was withdrawn on-line into the HPLC sample loop connected to the HF and then injected directly into the HPLC system for analysis. We found that the chlorophenols (CPs) could diffuse quickly through two sequential extraction interfaces - the donor phase - SLM and the SLM - acceptor phase - under the assistance of an ultrasonic probe. Ultrasonication provided effective mixing of the extracted boundary layers with the bulk of the sample and it increased the driving forces for mass transfer, thereby enhancing the extraction kinetics and leading to rapid enrichment of the target analytes. We studied the effects of various parameters on the extraction efficiency, viz. the nature of the SLM and acceptor phase, the compositions of the donor and acceptor phases, the fiber length, the stirring rate, the ion strength, the sample temperature, the sonication conditions, and the perfusion flow rate. This on-line extraction method exhibited linearity (r(2)≥0.998), sensitivity (limits of detection: 0.03-0.05 μg L(-1)), and precision (RSD%≤4.8), allowing the sensitive, simple, and rapid determination of CPs in aqueous solutions and water samples with a sampling time of just 2 min. PMID:23237709

  1. Model for the structure of the liquid water network

    SciTech Connect

    Grunwald, E.

    1986-09-17

    The state of a water molecule in liquid water is defined by its time-average network environment. Two states are characterized. State A is the familiar four-coordinated state of the Bernal-Fowler model with tetrahedral hydrogen bonds. State B is five-coordinated. Reexamination of the static dielectric constant by the method of Oster and Kirkwood confirms the marked polar character of the four-coordinated state but shows that the five-coordinated state is only about half as polar. Explicit five-coordinated models are proposed which are consistent with polarity and satisfy constraints of symmetry and hydrogen-bond stoichiometry. The potential energy due to the dipole-dipole interaction of the central water molecule with its time-average solvent network is derived without additional parameters. This permits prediction of barriers to rotation, frequencies for hindered rotation and liberation in the network, and ..delta..H/sub A,B/ and ..delta..S/sub A,B/. The results are in substantial agreement with relevant experiments. In particular, the barriers to rotation permit a consistent interpretation of the dielectric relaxation spectrum. The relative importance of the two states varies predictably with the property being examined, and this can account for some of the schizophrenia of aqueous properties. Since the two-state model is based on time-average network configurations, it does not apply when the time scale of observation is short compared to network frequencies, i.e., at infrared frequencies where continuum models may be successful.

  2. Statistical physics and liquid water at negative pressures

    NASA Astrophysics Data System (ADS)

    Stanley, H. Eugene; Barbosa, M. C.; Mossa, S.; Netz, P. A.; Sciortino, F.; Starr, F. W.; Yamada, M.

    2002-11-01

    Angell and his collaborators have underscored the importance of studying water under all extremes of pressure-squeezing to high pressures and stretching to negative pressures. Here we review recent results of molecular dynamics simulations of two models of liquid water, the extended simple point charge (SPC/E) and the Mahoney-Jorgensen transferable intermolecular potential with five points (TIP5P), which is closer to real water than previously proposed classical pairwise additive potentials. In particular, we describe simulations of the TIP5P model for a wide range of deeply supercooled states, including both positive and negative pressures, which reveal (i) the existence of a non-monotonic “nose-shaped” temperature of maximum density (TMD) line and a non-reentrant spinodal, (ii) the presence of a low-temperature phase transition. The TMD that changes slope from negative to positive as P decreases and, notably, the point of crossover between the two behaviors is located at ambient pressure (temperature ≈ 4° C, and density ≈ 1 g/cm3). We also describe simulations of the dynamics of the SPC/E model, which reveal (iii) the dynamics at negative pressure shows a minimum in the diffusion constant D when the density is decreased at constant temperature, complementary to the known maximum of D at higher pressures, and (iv) the loci of minima of D relative to the spinodal shows that they are inside the thermodynamically metastable regions of the phase diagram. These dynamical results reflect the initial enhancement and subsequent breakdown of the tetrahedral structure and of the hydrogen bond network as the density decreases.

  3. Evidence for Recent Liquid Water on Mars: Gullies

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Gully landforms proposed to have been caused by geologically-recent seepage and runoff of liquid water on Mars are found in the most unlikely places. They typically occur in areas that are quite cold, well below freezing all year round. Like the old adage about moss on trees, nearly all of them form on slopes that face away from sunlight. Most of the gullies occur at latitudes between 30 and 70. The highest latitude at which martian gullies have been found is around 70-75 S on the walls of pits developed in the south polar pitted plains. If you were at this same latitude on Earth, you would be in Antarctica. This region spends much of the winter--which lasts approximately 6 months on Mars--in darkness and at temperatures cold enough to freeze carbon dioxide (around -130C or -200F). Nevertheless, gullies with very sharp, deep, v-shaped channels are seen on the pit walls. Based upon the locations of the tops of the channels on the slope shown here, the inferred site of liquid seepage is located at a layer in the pit wall about 1/3 of the way down from the top of the MOC image. The channels start wide and taper downslope. The area above the channels is layered and has been eroded by mass movement dry avalanching of debris--to form a pattern of chutes and ridges on the upper slope of the pit wall. The top layer appears to have many boulders in it (each about the size of a small house), these boulders are left behind on the upper slopes of the pit wall as debris is removed.

  4. Investigation of the Extinguishing Features for Liquid Fuels and Organic Flammable Liquids Atomized by a Water Flow

    NASA Astrophysics Data System (ADS)

    Voytkov, Ivan V.; Zabelin, Maksim V.; Vysokomornaya, Olga V.

    2016-02-01

    The processes of heat and mass transfer were investigated experimentally while moving and evaporating the atomized water flow in high-temperature combustion products of typical liquid fuels and organic flammable liquids: gasoline, kerosene, acetone, crude oil, industrial alcohol. We determined typical periods of liquid extinguishing by an atomized water flow of various dispersability. Data of the discharge of extinguishing medium corresponding to various parameters of atomization and duration of using the atomization devices was presented. It is shown that Um≈3.5 m/s is a minimal outflow velocity of droplets during moving while passing the distance of 1m in the high-temperature gas medium to stop the combustion of organic liquids.

  5. Effects of water in film boiling over liquid metal melts

    SciTech Connect

    Greene, G.A.; Finfrock, C.; Burson, S.B.

    1986-01-01

    Liquid-liquid boiling experiments have been performed with H/sub 2/O and liquid metal melts in the 100-series test matrix (Runs 121, 126, 127) and the VE test matrix. Some of the pre-explosion unstable film boiling data as well as observations from the explosive series have been previously reported.

  6. Which shape characteristics of the intermolecular interaction of liquid water determine its compressibility ?

    NASA Astrophysics Data System (ADS)

    Yasutomi, Makoto

    2016-05-01

    We consider a fluid of spherical particles with a pair potential given by a hard core repulsion and a tail, and show that the isothermal compressibility of liquid water is determined by the degree of steepness of the soft repulsion near the hard-core contact. This helps us understand the thermodynamic mechanism that causes the compressibility anomaly of liquid water.

  7. ASSESSMENT OF THE LIQUID WATER CONTENT OF SUMMERTIME AEROSOL IN THE SOUTHEAST UNITED STATES

    EPA Science Inventory

    The concentration of aerosol liquid water mass represents an important parameter for understanding the physical properties of PM2.5 in the atmosphere. Increases in ambient relative humidity can increase aerosol liquid water and thus the composite particle mass and particle volu...

  8. Development of an ionic liquid based dispersive liquid-liquid microextraction method for the analysis of polycyclic aromatic hydrocarbons in water samples.

    PubMed

    Pena, M Teresa; Casais, M Carmen; Mejuto, M Carmen; Cela, Rafael

    2009-09-01

    A simple, rapid and efficient method, ionic liquid based dispersive liquid-liquid microextraction (IL-DLLME), has been developed for the first time for the determination of 18 polycyclic aromatic hydrocarbons (PAHs) in water samples. The chemical affinity between the ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate) and the analytes permits the extraction of the PAHs from the sample matrix also allowing their preconcentration. Thus, this technique combines extraction and concentration of the analytes into one step and avoids using toxic chlorinated solvents. The factors affecting the extraction efficiency, such as the type and volume of ionic liquid, type and volume of disperser solvent, extraction time, dispersion stage, centrifuging time and ionic strength, were optimised. Analysis of extracts was performed by high performance liquid chromatography (HPLC) coupled with fluorescence detection (Flu). The optimised method exhibited a good precision level with relative standard deviation values between 1.2% and 5.7%. Quantification limits obtained for all of these considered compounds (between 0.1 and 7 ng L(-1)) were well below the limits recommended in the EU. The extraction yields for the different compounds obtained by IL-DLLME, ranged from 90.3% to 103.8%. Furthermore, high enrichment factors (301-346) were also achieved. The extraction efficiency of the optimised method is compared with that achieved by liquid-liquid extraction. Finally, the proposed method was successfully applied to the analysis of PAHs in real water samples (tap, bottled, fountain, well, river, rainwater, treated and raw wastewater). PMID:19646707

  9. REVIEW ARTICLE: The high-frequency dynamics of liquid water

    NASA Astrophysics Data System (ADS)

    Ruocco, Giancarlo; Sette, Francesco

    1999-06-01

    This article is dedicated to reviewing the recent inelastic x-ray scattering (IXS) work on the high-frequency collective dynamics in liquid water. The results obtained with the IXS technique are directly compared with existing ones from inelastic neutron scattering (INS) and molecular dynamics simulation investigations that were carried out with the aim of achieving an understanding of the collective properties of water at the microscopic level. The IXS work has made it possible to demonstrate experimentally the existence, in the range of exchange momentum (Q) examined (1-10 nm-1), of two branches of collective modes: one linearly dispersing with Q (with the apparent sound velocity of icons/Journals/Common/approx" ALT="approx" ALIGN="TOP"/>3200 m s-1) and the other at almost constant energy (5-7 meV). It has been possible to show that the dispersing branch originates from an upwards bend of the ordinary sound branch observed in low-frequency measurements. The study of this sound velocity dispersion, marking a transition from the ordinary sound, co, to the `fast' sound, cicons/Journals/Common/infty" ALT="infty" ALIGN="MIDDLE"/>, as a function of temperature, has made it possible to relate the origin of this phenomenon to a structural relaxation process, which presents many analogies with those observed for glass-forming systems. The possibility of estimating from the IXS data the value of the relaxation time, icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/>, as a function of temperature leads to a relating of the relaxation process to the structural rearrangements induced by the making and breaking of hydrogen bonds. In this framework, it is then possible to recognize a hydrodynamical `normal' regime, i.e. one for which the density fluctuations have a period of oscillation that is on a timescale that is long with respect to icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/>, and a solid-like regime in the opposite limit. In the latter regime, the density

  10. Liquid-Liquid Phase Transition and Its Phase Diagram in Deeply-Cooled Heavy Water Confined in a Nanoporous Silica Matrix.

    PubMed

    Wang, Zhe; Ito, Kanae; Leão, Juscelino B; Harriger, Leland; Liu, Yun; Chen, Sow-Hsin

    2015-06-01

    Using neutron diffraction technique, we measure the average density of the heavy water confined in a nanoporous silica matrix, MCM-41, over the pressure-temperature plane. The result suggests the existence of a line of liquid-liquid phase transition with its end point at 1.29 ± 0.34 kbar and 213 ± 3 K in a fully hydrated sample. This point would be the liquid-liquid critical point (LLCP) according to the "liquid-liquid critical point" scenario. The phase diagram of the deeply cooled confined heavy water is then discussed. Moreover, in a partially hydrated sample, the phase transition completely disappears. This result shows that it is the free water part, rather than the bound water part, of the confined water that undergoes a liquid-liquid transition. PMID:26266493

  11. Evaporation of Ethanol-Water Binary Mixture Sessile Liquid Marbles.

    PubMed

    Ooi, Chin Hong; Bormashenko, Edward; Nguyen, Anh V; Evans, Geoffrey M; Dao, Dzung V; Nguyen, Nam-Trung

    2016-06-21

    Liquid marble is a liquid droplet coated with particles. Recently, the evaporation process of a sessile liquid marble using geometric measurements has attracted great attention from the research community. However, the lack of gravimetric measurement limits further insights into the physical changes of a liquid marble during the evaporation process. Moreover, the evaporation process of a marble containing a liquid binary mixture has not been reported before. The present paper investigates the effective density and the effective surface tension of an evaporating liquid marble that contains aqueous ethanol at relatively low concentrations. The effective density of an evaporating liquid marble is determined from the concurrent measurement of instantaneous mass and volume. Density measurements combined with surface profile fitting provide the effective surface tension of the marble. We found that the density and surface tension of an evaporating marble are significantly affected by the particle coating. PMID:27230102

  12. Apparent First-Order Liquid-Liquid Transition with Pre-transition Density Anomaly, in Water-Rich Ideal Solutions.

    PubMed

    Zhao, Zuofeng; Angell, C Austen

    2016-02-12

    The striking increases in response functions observed during supercooling of pure water have been the source of much interest and controversy. Imminent divergences of compressibility etc. unfortunately cannot be confirmed due to pre-emption by ice crystallization. Crystallization can be repressed by addition of second components, but these usually destroy the anomalies of interest. Here we study systems in which protic ionic liquid second components dissolve ideally in water, and ice formation is avoided without destroying the anomalies. We observe a major heat capacity spike during cooling, which is reversed during heating, and is apparently of first order. It occurs just before the glassy state is reached and is preceded by water-like density anomalies. We propose that it is the much-discussed liquid-liquid transition previously hidden by crystallization. Fast cooling should allow the important fluctuations/structures to be preserved in the glassy state for leisurely investigation. PMID:26756943

  13. Cloud Liquid Water Content Variability over the Indian Region

    NASA Astrophysics Data System (ADS)

    Kandalgaonkar, S. S.; Padma Kumari, B.; Kulkarni, J. R.

    2010-05-01

    This paper presents the aircraft measurements of liquid water content (LWC) which are taken during three different missions organized by Institutes ongoing CAIPEEX project. The three missions are Pathankot (32.2250N, 75.6340E); Hyderabad (17.4480N,78.3810E,) and Bangalore (13.1350N, 77.6150E) respectively. The LWC data is collected for fifteen flight days at the above locations. Each second LWC values are analyzed to study their vertical and frequency distribution. The preliminary results of this study show that the nature of LWC profile at above three locations is same showing the average LWC as 0.28, 0.33 and .036 gm m-3 respectively. The range of LWC varies at all three locations. It is minimum at Pathankot and maximum at Bangalore. The LWC values are compared with the adiabatic values at the same temperature, pressure and humidity conditions. The analysis shows consistent small adiabatic fraction in all the cases. The horizontal and vertical distributions of LWC have been studied. In the horizontal a large spread has been observed. The maximum LWC has been found to increase steeply over Pathankot and gently over Bangalore.

  14. Dissociative ionization of liquid water induced by vibrational overtone excitation

    SciTech Connect

    Natzle, W.C.

    1983-03-01

    Photochemistry of vibrationally activated ground electronic state liquid water to produce H/sup +/ and OH/sup -/ ions has been initiated by pulsed, single-photon excitation of overtone and combination transitions. Transient conductivity measurements were used to determine quantum yields as a function of photon energy, isotopic composition, and temperature. The equilibrium relaxation rate following perturbation by the vibrationally activated reaction was also measured as a function of temperature reaction and isotopic composition. In H/sub 2/O, the quantum yield at 283 +- 1 K varies from 2 x 10/sup -9/ to 4 x 10/sup -5/ for wave numbers between 7605 and 18140 cm/sup -1/. In D/sub 2/O, the dependence of quantum yield on wavelength has the same qualitative shape as for H/sub 2/O, but is shifted to lower quantum yields. The position of a minimum in the quantum yield versus hydrogen mole fraction curve is consistent with a lower quantum yield for excitation of HOD in D/sub 2/O than for excitation of D/sub 2/O. The ionic recombination distance of 5.8 +- 0.5 A is constant within experimental error with temperature in H/sub 2/O and with isotopic composition at 25 +- 1/sup 0/C.

  15. Mutual solubility of water and structural/positional isomers of N-alkylpyridinium-based ionic liquids.

    PubMed

    Freire, Mara G; Neves, Catarina M S S; Shimizu, Karina; Bernardes, Carlos E S; Marrucho, Isabel M; Coutinho, João A P; Canongia Lopes, José N; Rebelo, Luís Paulo N

    2010-12-01

    Despite many previous important contributions to the characterization of the liquid-liquid phase behavior of ionic liquids (ILs) plus water systems, a gap still exists as far as the effect of isomers (of ILs) is concerned. Therefore, in this work, a comprehensive study of the liquid-liquid equilibria between water and isomeric pyridinium-based ionic liquids has been performed. Atmospheric pressure mutual solubilities between water and pyridinium-based ionic liquids combined with the common anion bis[(trifluoromethyl)sulfonyl]imide were experimentally determined between (288.15 and 318.15) K. The main goal of this work is to study the isomeric effects on the pyridinium-based cation, namely, the structural and positional isomerism, as well as the alkyl side chain length. To the best of our knowledge, the influence of both structural and positional isomerism on the liquid-liquid behavior in ionic-liquid-water-containing systems is an unexplored field and is here assessed for the first time. Moreover, from the experimental solubility data, several infinite dilution molar thermodynamic functions of solution, namely, the Gibbs energy, the enthalpy, and the entropy, were estimated and discussed. In addition, aiming at gathering a broader picture of the underlying thermodynamic solvation phenomenon, molecular dynamics simulations were also carried out for the same experimental systems. PMID:21077599

  16. Ionic liquid integrated multiwalled carbon nanotube in a poly(vinylidene fluoride) matrix: formation of a piezoelectric β-polymorph with significant reinforcement and conductivity improvement.

    PubMed

    Mandal, Amit; Nandi, Arun K

    2013-02-01

    Multiwalled carbon nanotubes (MWNTs) are functionalized covalently with ionic liquid (IL, 3-aminoethyl imidazolium bromide) which helps good dispersion of IL-functionalized MWNTs (MWNT-IL) in the poly(vinylidene fluoride) (PVDF) matrix. Analysis of transmission electron microscopy (TEM) micrographs suggests ∼10 nm coating thickness of MWNTs by ILs, and the covalent linkage of ILs with MWNTs is confirmed from FT-IR and Raman spectra. PVDF nanocomposites with full β-polymorphic (piezoelectric) form are prepared using MWNT-IL by both the solvent cast and melt-blending methods. The FE-SEM and TEM micrographs indicate that IL-bound MWNTs are homogeneously dispersed within the PVDF matrix. Increasing MWNT-IL concentration in the composites results in increased β polymorph formation with a concomitant decrease of the α polymorph, and a 100% β polymorph formation occurs for 1 wt % MWNT-IL in both the fabrication conditions. A differential scanning calorimetry (DSC) study shows that the MWNT-ILs are an efficient nucleating agent for PVDF crystallization preferentially nucleating the β form due to its dipolar interactions with PVDF. The glass transition temperature (T(g)) gradually increases with an increase in MWNT-IL concentration, and the storage modulus (G') of the composites increases significantly, showing a maximum increase of 101.3% for 0.5 wt % MWNT-IL. The Young's modulus increases with MWNT-IL concentration, and analysis of the data using the Halpin-Tsai equation suggests that at low concentration they adopt an orientation parallel to the film surface; however, at higher MWNT-IL concentration it is randomly oriented. The tensile strength also increases with an increase in MWNT-IL concentration, and both the Young's modulus and the tensile strength of solvent cast films are lower than melt-blended samples. The elongation at break in the solvent cast samples shows a maximum, but in melt-blended samples it decreases continuously with increasing MWNT

  17. Electrochemical anomalies of protic ionic liquid - Water systems: A case study using ethylammonium nitrate - Water system

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Nakama, Kazuya; Hayashi, Ryotaro; Aono, Masami; Takekiyo, Takahiro; Yoshimura, Yukihiro; Saihara, Koji; Shimizu, Akio

    2016-08-01

    Electrochemical impedance spectroscopy was used to evaluate protic ionic liquid (pIL)-water mixtures in the temperature range of -35-25 °C. The pIL used in this study was ethylammonium nitrate (EAN). At room temperature, the resonant mode of conductivity was observed in the high frequency region. The anomalous conductivity disappeared once solidification occurred at low temperatures. The kinetic pH of the EAN-water system was investigated at a fixed temperature. Rhythmic pH oscillations in the EAN-H2O mixtures were induced at 70 < x < 90 mol% H2O. The electrochemical instabilities in a EAN-water mixture are caused in an intermediate state between pIL and bulk water. From the ab initio calculations, it was observed that the dipole moment of the EAN-water complex shows a discrete jump at around 85 mol% H2O. Water-mediated hydrogen bonding network drastically changes at the crossover concentration.

  18. Column atmospheric water vapor and vegetation liquid water retrievals from airborne imaging spectrometer data

    SciTech Connect

    Bo-Cai Gao; Goetz, A.F.H. )

    1990-03-20

    High spatial resolution column atmospheric water vapor amounts were derived from spectral data collected by the airborne visible-infrared imaging spectrometer (AVIRIS). The quantitative derivation is made by curve fitting observed spectra with calculated spectra in the 1.14-{mu}m and 0.94-{mu}m water vapor band absorption regions using an atmospheric model, a narrow-band spectral model, and a nonlinear least squares fitting technique. The derivation makes use of the facts that (1) the reflectances of many ground targets vary approximately linearly with wavelength in the 0.94- and 1.14-{mu}m water vapor band absorption regions, (2) the scattered radiation near 1 {mu}m is small compared with the directly reflected radiation when the atmospheric aerosol concentrations are low, and (3) the scattered radiation in the lower part of the atmosphere is subjected to the water vapor absorption. Based on the analyses of an AVIRIS data set that was acquired within an hour of radiosonde launch, it appears that the accuracy approaches the precision. The derived column water vapor amounts are independent of the absolute surface reflectances. It now appears feasible to derive high spatial resolution column water vapor amounts over land areas from satellite altitude with the proposed high resolution imaging spectrometer (HIRIS). Curve fitting of spectra near 1 {mu}m from areas covered with vegetation, using an atmospheric model and a simplified vegetation reflectance model, indicates that both the amount of atmospheric water vapor and the moisture content of vegetation can be retrieved simultaneously because the band centers of liquid water in vegetation and the atmospheric water vapor are offset by approximately 0.05 {mu}m.

  19. Improved compensation of liquid water spectral effects in the DOAS analysis (410-500 nm)

    NASA Astrophysics Data System (ADS)

    Peters, Enno; Wittrock, Folkard; Richter, Andreas; Burrows, John P.

    2014-05-01

    It is well known that spectral effects of liquid water are present in DOAS measurements above the ocean. Usually, the effects of surface reflectance are successfully compensated by a broadband polynomial. In addition, the absorption of liquid water and Vibrational Raman Scattering (VRS) in the water body can be considered in the DOAS fit by including the respective (literature) cross-sections. Here, ship-based MAX-DOAS measurements collected during the TransBrom campaign across the Western Pacific in October 2009 are presented. For these observations, the telescope of the instrument was pointing directly into very clear natural sea-water. These measurements were performed in a way minimizing atmospheric contributions to the resulting optical depth while at the same time maximizing the liquid water influence. Average light paths of up to 50 m under water were achieved. Systematic structures were found to remain in DOAS fit residuals in the visible wavelength range even if liquid water spectral effects are included in the fit. It can therefore be concluded that currently available cross-sections compensate liquid water effects only insufficiently in DOAS applications. Thus, empirical correction spectra for uncertainties of currently available liquid water absorption and VRS cross-sections were determined from the MAX-DOAS measurements. The influence of the retrieved correction spectra on fit quality and NO2 slant columns is estimated in MAX-DOAS measurements, both towards the water surface and at small elevation angles above the horizon.

  20. Degassifying and mixing apparatus for liquids. [potable water for spacecraft

    NASA Technical Reports Server (NTRS)

    Yamauchi, S. T. (Inventor)

    1983-01-01

    An apparatus for degassing a liquid comprises a containment vessel a liquid pump and a header assembly (12) within the containment vessel in a volume above the reservoir of the liquid. The pump draws from this reservoir and outputs to the header assembly, the latter being constructed to return the liquid to the reservoir in the form of a number of stacked, vertically spaced, concentric, conical cascades via orifices. A vacuum source provides a partial vacuum in the containment vessel to enhance the degassing process.

  1. Water-saving liquid-gas conditioning system

    SciTech Connect

    Martin, Christopher; Zhuang, Ye

    2014-01-14

    A method for treating a process gas with a liquid comprises contacting a process gas with a hygroscopic working fluid in order to remove a constituent from the process gas. A system for treating a process gas with a liquid comprises a hygroscopic working fluid comprising a component adapted to absorb or react with a constituent of a process gas, and a liquid-gas contactor for contacting the working fluid and the process gas, wherein the constituent is removed from the process gas within the liquid-gas contactor.

  2. Determination of water in room temperature ionic liquids by cathodic stripping voltammetry at a gold electrode.

    PubMed

    Zhao, Chuan; Bond, Alan M; Lu, Xunyu

    2012-03-20

    An electrochemical method based on cathodic stripping voltammetry at a gold electrode has been developed for the determination of water in ionic liquids. The technique has been applied to two aprotic ionic liquids, (1-butyl-3-ethylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium hexafluorophosphate), and two protic ionic liquids, (bis(2-hydroxyethyl)ammonium acetate and triethylammonium acetate). When water is present in an ionic liquid, electrooxidation of a gold electrode forms gold oxides. Thus, application of an anodic potential scan or holding the potential of the electrode at a very positive value leads to accumulation of an oxide film. On applying a cathodic potential scan, a sensitive stripping peak is produced as a result of the reduction of gold oxide back to gold. The magnitude of the peak current generated from the stripping process is a function of the water concentration in an ionic liquid. The method requires no addition of reagents and can be used for the sensitive and in situ determination of water present in small volumes of ionic liquids. Importantly, the method allows the determination of water in the carboxylic acid-based ionic liquids, such as acetate-based protic ionic liquids, where the widely used Karl Fischer titration method suffering from an esterification side reaction which generates water as a side product. PMID:22372467

  3. A Simple Technique of Liquid Purity Analysis and Its Application to Analysis of Water Concentration in Alcohol-Water Mixtures

    NASA Astrophysics Data System (ADS)

    de, Dilip; Aziz de, Abdul

    2012-10-01

    The change of activation energy of a liquid molecule and hence its viscosity coefficient with addition of contaminants to the original liquid gives rise to a new technology for analysis of purity of the liquid. We discovered that concentration of certain contaminants such as water in alcohol or vice versa can be uniquely and accurately determined in a short time (about 10-15 minutes) using a simple and yet innovative technique that only requires measurement of time of flow of the impure liquid (say, water-alcohol mixture) and distilled water through a simple viscometer. We determined the increase of activation energy of alcohol molecules with increase of water concentration for ethyl and methyl alcohol. Our detailed investigation on the alcohol-water mixtures along with discussion on possible future potential application of the simple and very reliable inexpensive technique for liquid purity analysis is presented. We compared our present method with other methods on the accuracies, problems and reliability of impurity analysis in liquids. We also discuss a part of the quantum theory of viscosity of liquid mixtures that is in the developmental stage.

  4. Revisiting a many-body model for water based on a single polarizable site: From gas phase clusters to liquid and air/liquid water systems

    NASA Astrophysics Data System (ADS)

    Réal, Florent; Vallet, Valérie; Flament, Jean-Pierre; Masella, Michel

    2013-09-01

    We present a revised version of the water many-body model TCPE [M. Masella and J.-P. Flament, J. Chem. Phys. 107, 9105 (1997)], which is based on a static three charge sites and a single polarizable site to model the molecular electrostatic properties of water, and on an anisotropic short range many-body energy term specially designed to accurately model hydrogen bonding in water. The parameters of the revised model, denoted TCPE/2013, are here developed to reproduce the ab initio energetic and geometrical properties of small water clusters (up to hexamers) and the repulsive water interactions occurring in cation first hydration shells. The model parameters have also been refined to reproduce two liquid water properties at ambient conditions, the density and the vaporization enthalpy. Thanks to its computational efficiency, the new model range of applicability was validated by performing simulations of liquid water over a wide range of temperatures and pressures, as well as by investigating water liquid/vapor interfaces over a large range of temperatures. It is shown to reproduce several important water properties at an accurate enough level of precision, such as the existence liquid water density maxima up to a pressure of 1000 atm, the water boiling temperature, the properties of the water critical point (temperature, pressure, and density), and the existence of a "singularity" temperature at about 225 K in the supercooled regime. This model appears thus to be particularly well-suited for characterizing ion hydration properties under different temperature and pressure conditions, as well as in different phases and interfaces.

  5. Revisiting a many-body model for water based on a single polarizable site: from gas phase clusters to liquid and air/liquid water systems.

    PubMed

    Réal, Florent; Vallet, Valérie; Flament, Jean-Pierre; Masella, Michel

    2013-09-21

    We present a revised version of the water many-body model TCPE [M. Masella and J.-P. Flament, J. Chem. Phys. 107, 9105 (1997)], which is based on a static three charge sites and a single polarizable site to model the molecular electrostatic properties of water, and on an anisotropic short range many-body energy term specially designed to accurately model hydrogen bonding in water. The parameters of the revised model, denoted TCPE/2013, are here developed to reproduce the ab initio energetic and geometrical properties of small water clusters (up to hexamers) and the repulsive water interactions occurring in cation first hydration shells. The model parameters have also been refined to reproduce two liquid water properties at ambient conditions, the density and the vaporization enthalpy. Thanks to its computational efficiency, the new model range of applicability was validated by performing simulations of liquid water over a wide range of temperatures and pressures, as well as by investigating water liquid/vapor interfaces over a large range of temperatures. It is shown to reproduce several important water properties at an accurate enough level of precision, such as the existence liquid water density maxima up to a pressure of 1000 atm, the water boiling temperature, the properties of the water critical point (temperature, pressure, and density), and the existence of a "singularity" temperature at about 225 K in the supercooled regime. This model appears thus to be particularly well-suited for characterizing ion hydration properties under different temperature and pressure conditions, as well as in different phases and interfaces. PMID:24070292

  6. Spin Crossover, Polymorphism and Porosity to Liquid Solvent in Heteroleptic Iron(III) {Quinolylsalicylaldimine/Thiosemicarbazone-Salicylaldimine} Complexes.

    PubMed

    Phonsri, Wasinee; Davies, Casey G; Jameson, Guy N L; Moubaraki, Boujemaa; Murray, Keith S

    2016-01-22

    Heteroleptic iron(III) complexes of formula [Fe(qsal)(thsa)]⋅solvent have been synthesized: [Fe(qsal)(thsa)]⋅0.4 BuOH (1), [Fe(qsal)(thsa)]⋅0.5 MeCN (2) and [Fe(qsal)(thsa)]⋅0.5 THF, (3). The latter two show partial solvent loss at room temperature to yield [Fe(qsal)(thsa)]⋅0.1 MeCN (2') and [Fe(qsal)(thsa)]⋅0.1 THF (3'), respectively. This family maintains a structural integrity which is analogous over different degrees of solvation, a rare occurrence in discrete molecular species. Uniquely, removal of MeCN from compound 2 leads to retention of crystallinity yielding the isostructural, fully desolvated compound [Fe(qsal)(thsa)] (2'') and a new high spin polymorph, 4. To the best of our knowledge, this is the first compound that forms polymorphs through a desolvation process. The desolvated mixture, 2'' and 4, is porous and can reabsorb MeCN and give rise to 2' again. This illustrates the reversible single-crystal-to-single-crystal transformation of two polymorphs back to a purely original phase, 2''+4↔2'. The structural, magnetic and Mőssbauer features of the various samples are described in terms of spin crossover. PMID:26662933

  7. Water in ionic liquids at electrified interfaces: the anatomy of electrosorption.

    PubMed

    Feng, Guang; Jiang, Xikai; Qiao, Rui; Kornyshev, Alexei A

    2014-11-25

    Complete removal of water from room-temperature ionic liquids is nearly impossible. For the electrochemical applications of ionic liquids, how water is distributed in the electrical double layers when the bulk liquids are not perfectly dry can potentially determine whether key advantages of ionic liquids, such as a wide electrochemical window, can be harnessed in practical systems. In this paper, we study the adsorption of water on electrode surfaces in contact with humid, imidazolium-based ionic liquids using molecular dynamics simulations. The results revealed that water molecules tend to accumulate within sub-nanometer distance from charged electrodes. At low amount of water in the bulk, the distributions of ions and of electrostatic potential in the double layer are affected weakly by the presence of water, but the spatial distribution of water molecules is strongly dependent on both. The preferential positions of water molecules in double layers are determined by the balance of several factors: the tendency to follow the positions of the maximal absolute value of the electrical field, the association with their ionic surroundings, and the propensity to settle at positions where more free space is available. The balance between these factors changes with charging the electrode, but the adsorption of water generally increases with voltage. The ion specificity of water electrosorption is manifested in the stronger presence of water near positive electrodes (where anions are the counterions) than near negative electrodes (where cations are counterions). These predictions await experimental verification. PMID:25341189

  8. Determination of integrated cloud liquid water and total precipitable water using a neural network algorithm

    NASA Astrophysics Data System (ADS)

    Moreau, Emmanuel; Mallet, Cecile; Casagrande, Luc; Klapisz, Claude

    1998-08-01

    A new algorithms is developed whereby the cloud liquid water path (LWP) and the total precipitable water (TPW) may be determined from microwave radiometric data. A large meteorological database obtained from the European Centre for Medium-Range Weather Forecasts forecast model is used to simulate, with a radiative transfer model, brightness temperatures (TB) at the top of the atmosphere for the special sensor microwave imagery frequencies. A single- hidden-layer ANN was used. An error backpropagation training algorithm was applied to train the ANN. A first comparison with a log-linear regression algorithm, shows that the ANN can represent more accurately the underlying relationship between TB and, TPW and LWP. The ANN seems to be able to give a better fit at large values of LWP. Furthermore in the case of TPW, a validation is made with radiosonde data, with another new algorithm.

  9. Estimated accuracy of ground-based liquid water measurements during FIRE

    NASA Technical Reports Server (NTRS)

    Snider, Jack B.

    1990-01-01

    Since on goal of the First ISCCP Regional Experiment (FIRE) project is to improve our understanding of the relationships between cloud microphysics and cloud reflectivity, it is important that the accuracy of remote liquid measurements by microwave radiometry be thoroughly understood. The question is particularly relevant since the uncertainty in the absolute value of the radiometric liquid measurement is greatest at low liquid water contents (less than 0.1 mm). However it should be stressed that although uncertainty exists in the absolute value of liquid, it is well known that the observed radiometric signal is proportional to the amount of liquid in the antenna beam. As a result, changes in amounts of liquid are known to greater accuracy than the absolute value, which may contain a bias. Here, an assessment of the liquid measurement accuracy attained at San Nicolas Island (SNI) is presented. The vapor and liquid water data shown were computed from the radiometric brightness temperatures using statistical retrieval algorithms. The retrieval coefficients were derived from the 69 soundings made by Colorado State University during the SNI observations. Sources of error in the vapor and liquid measurements include cross-talk in the retrieval algorithms (not a factor at low liquid contents), uncertainties in the brightness temperature measurement, and uncertainties in the vapor and liquid attenuation coefficients. The relative importance of these errors is discussed. For the retrieval of path-integrated liquid water, the greatest uncertainty is caused by the temperature dependence of the absorption at microwave frequencies. As a result, the accuracy of statistical retrieval of liquid depends to large measure upon how representative the a priori radiosonde data are of the conditions prevailing during the measurements. The microwave radiometer measurements at SNI were supplemented by an infrared (IR) radiometer modified for measurement of cloud-base temperature. Thus

  10. Nimbus 7 SMMR derived seasonal variations in the water vapor, liquid water, and surface winds over the global oceans

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Short, D. A.

    1984-01-01

    A study based on monthly mean maps of atmospheric water vapor, liquid water, and surface wind derived from Nimbus-7 SMMR over the oceans for 13 months, is examined. A discussion of the retrieval technique used to derive the parameters is presented. The seasonal changes in the strength and position of several of the parameter features are revealed by the December 1978 and June 1979 maps. Zonal averages of the water vapor, liquid water, and surface wind for December and June are compared with information derived from conventional measurements and the results are presented in graphs.

  11. Another glimpse over the salting-out assisted liquid-liquid extraction in acetonitrile/water mixtures.

    PubMed

    Valente, Inês Maria; Gonçalves, Luís Moreira; Rodrigues, José António

    2013-09-20

    The use of the salting-out effect in analytical chemistry is very diverse and can be applied to increase the volatility of the analytes in headspace extractions, to cause the precipitation of proteins in biological samples or to improve the recoveries in liquid-liquid extractions. In the latter, the salting-out process can be used to create a phase separation between water-miscible organic solvents and water. Salting-out assisted liquid-liquid extraction (SALLE) is an advantageous sample preparation technique aiming HPLC-UV analysis when developing analytical methodologies. In fact, some new extraction methodologies like QuEChERS include the SALLE concept. This manuscript discusses another point of view over SALLE with particular emphasis over acetonitrile-water mixtures for HPLC-UV analysis; the influence of the salting-out agents, their concentration and the water-acetonitrile volume ratios were the studied parameters. α-dicarbonyl compounds and beer were used as test analytes and test samples, respectively. The influence of the studied parameters was characterized by the obtained phase separation volume ratio and the fraction of α-dicarbonyls extracted to the acetonitrile phase. Results allowed the distribution of salts within three groups according to the phase separation and their extractability: (1) chlorides and acetates, (2) carbonates and sulfates and (3) magnesium sulfate; of all tested salts, sodium chloride had the highest influence on the α-dicarbonyls fraction extracted. PMID:23958692

  12. Explaining Ionic Liquid Water Solubility in Terms of Cation and Anion Hydrophobicity

    PubMed Central

    Ranke, Johannes; Othman, Alaa; Fan, Ping; Müller, Anja

    2009-01-01

    The water solubility of salts is ordinarily dictated by lattice energy and ion solvation. However, in the case of low melting salts also known as ionic liquids, lattice energy is immaterial and differences in hydrophobicity largely account for differences in their water solubility. In this contribution, the activity coefficients of ionic liquids in water are split into cation and anion contributions by regression against cation hydrophobicity parameters that are experimentally determined by reversed phase liquid chromatography. In this way, anion hydrophobicity parameters are derived, as well as an equation to estimate water solubilities for cation-anion combinations for which the water solubility has not been measured. Thus, a new pathway to the quantification of aqueous ion solvation is shown, making use of the relative weakness of interactions between ionic liquid ions as compared to their hydrophobicities. PMID:19399248

  13. Polymorphism of triphenyl phosphite

    NASA Astrophysics Data System (ADS)

    Baran, J.; Davydova, N. A.; Drozd, M.

    2014-03-01

    The glass-forming liquid triphenyl phosphite (TPP) has recently attracted much attention due to the possible existence of a polyamorphism, i.e., the existence of two or more amorphous phases. In the present work we provide experimental evidence of the existence of a polymorphism in TPP. In addition to the already known conventional crystalline phase, which melts at 299.1 K, it has been found that TPP can crystallize in another polymorphic phase. The new polymorph can be obtained from the liquid phase due to direct cooling from the room temperature up to 245 K where it is held for 15 min and then heated up to 270 K. At 270 K crystallization of the new polymorph occurs, which melts at 291.6 K.

  14. Using nanoscale amorphous solid water films to create and study deeply supercooled liquid water at interfaces

    NASA Astrophysics Data System (ADS)

    Kay, Bruce

    Molecular beam vapor deposition of water on cryogenic substrates is known to produce amorphous solid films. When heated above their glass transition these films transform into deeply supercooled liquid water. These nanoscale liquid films can be used to study kinetic processes such as diffusion, isotope exchange, crystallization, and solvent mediated reactions in unprecedented detail. This talk will highlight our recent advances in this area. My colleagues Yuntao Xu, Chunqing Yuan, Collin Dibble, R. Scott Smith, Nick Petrik, and Greg Kimmel made important contributions to this work.This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. The research was performed using EMSL, a national scientific user facility sponsored by DOE's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory, which is operated by Battelle, operated for the U.S. DOE under Contract DE-AC05-76RL01830.

  15. Quaternary liquid/liquid equilibria of sodium sulfate, sodium sulfite and water with two solvents: Acetone and 2-propanol

    SciTech Connect

    Schiozer, A.L.

    1994-03-01

    Aqueous solutions of sodium sulfate and sodium sulfite are produced from sodium carbonate in flue-gas scrubbers; recovery of these salts often requires multi-effect evaporators; however, a new energy-efficient unit operation called extractive crystallization has been shown to have reduced energy costs. In this process, an organic solvent is added to the aqueous salt solution to precipitate salt. Acetone is a suitable solvent for this process, better than 2-propanol. Liquid/liquid/solid equilibria for ternary systems containing a salt, water, and an organic solvent were measured. Systems investigated were sodium sulfite/water/acetone and sodium sulfite/water/2-propanol. Experiments were conducted at salt saturation covering a temperature range between the lower consolute temperature and 48.6{degrees}C. In the attempt to improve the extractive crystallization process for recovery of sodium sulfate from flue-gas scrubbers, attention was given to a feed containing a mixture of sodium sulfite and sodium sulfate. Liquid-liquid equilibria for quaternary systems containing two salts, water, and an organic solvent were experimentally determined at 35{degrees}C. The systems investigated were sodium sulfate/sodium sulfite/water/acetone and sodium sulfate/sodium sulfite/water/2propanol. The systems were studied at three salt ratios. For each salt ratio, experiments were conducted starting at saturation, water was then added until the one-phase region was reached. Mixtures of the two salts proved to have a small disadvantage relative to the 100 % sulfate feed process. Therefore, a sulfate-based extractive crystallization process is recommended.

  16. Primitive Liquid Water of the Solar System in an Aqueous Altered Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Tsuchiyama, A.; Miyake, A.; Kitayama, A.; Matsuno, J.; Takeuchi, A.; Uesugi, K.; Suzuki, Y.; Nakano, T.; Zolensky, M. E.

    2016-01-01

    Non-destructive 3D observations of the aqueous altered CM chondrite Sutter's Mill using scanning imaging x-ray microscopy (SIXM) showed that some of calcite and enstatite grains contain two-phase inclusion, which is most probably composed of liquid water and bubbles. This water should be primitive water responsible for aqueous alteration in an asteroid in the early solar system.

  17. Nuclear magnetic resonance in water solutions of inorganic salts in vitreous and liquid states

    SciTech Connect

    Lundin, A. G. Koryavko, N. A.; Chichikov, S. A.

    2013-05-15

    Peculiarities of the behavior of water solutions of inorganic salts at temperatures of {approx}(120-150) K are examined. At these temperatures the solutions are in the vitreous state. At higher temperatures (up to 240 K) the solutions may be in metastable liquid, crystalline, or usual liquid states.

  18. Homogeneous liquid-liquid extraction of metal ions with non-fluorinated bis(2-ethylhexyl)phosphate ionic liquids having a lower critical solution temperature in combination with water.

    PubMed

    Depuydt, Daphne; Liu, Liwang; Glorieux, Christ; Dehaen, Wim; Binnemans, Koen

    2015-09-28

    Ionic liquids with an ether-functionalised cation and the bis(2-ethylhexyl)phosphate anion show thermomorphic behaviour in water, with a lower critical solution temperature. These ionic liquids are useful for homogeneous liquid-liquid extraction of first-row (3d) transition metals. PMID:26255754

  19. Tailored ionic liquid-based surfactants for the formation of microemulsions with water and a hydrophobic ionic liquid.

    PubMed

    Porada, Jan H; Zauser, Diana; Feucht, Birgit; Stubenrauch, Cosima

    2016-08-14

    Microemulsions (μe) with water and a hydrophobic ionic liquid (IL) usually require 45-60 wt% surfactant to solubilize equal amounts of water and IL. To increase the efficiency we designed a new class of surfactants by combining a hydrophilic but IL-ophobic carbohydrate-based part with a hydrophobic but IL-ophilic IL-based part. These surfactants allow formulating microemulsions with 20 wt% surfactant only which opens up a new arena for efficient water-IL μes. PMID:27405741

  20. CYP1A1 and GSTM1 genetic polymorphisms in lung cancer populations exposed to arsenic in drinking water.

    PubMed

    Adonis, M; Martínez, V; Marín, P; Gil, L

    2005-05-01

    Region II of Chile is the most important copper mining area in the world and it shows the highest lung cancer mortality rate in the country (35/100,000). The population in Antofagasta, the main city of Region II, was exposed from 1958 to 1970 to 860 microg m(-3) arsenic (As) in drinking water and has currently been declining to 40 microg m(-3). Glutathione serves as a reducing agent and glutathione S-transferase (GST) may have an important role in As methylation capacity and body retention. In the current study, the null genotype of GSTM1 and the MspI polymorphism of CYP450 1A1 were investigated in lung cancer patients and in healthy volunteers of Region II. In males, the 2A genotype of MspI represented a highly significant estimated relative lung cancer risk (OR=2.60). Relative lung cancer risk for the combined 2A/null GSTM1 genotypes was 2.51, which increased with the smoking habit (OR=2.98). In Region II, the cancer mortality rate for As-associated cancers at least partly might be related to differences in As biotransformation. Genetic biomarkers such as 2A and GSTM1 polymorphisms in addition to DR70 as screening biomarkers might provide relevant information to identify individuals with a high risk for lung cancer as prevention and protection actions to protect public health. PMID:16012082

  1. Process for hydrogen isotope concentration between liquid water and hydrogen gas

    DOEpatents

    Stevens, William H.

    1976-09-21

    A process for hydrogen isotope exchange and concentration between liquid water and hydrogen gas, wherein liquid water and hydrogen gas are contacted, in an exchange section, with one another and with at least one catalyst body comprising at least one metal selected from Group VIII of the Periodic Table and preferably a support therefor, the catalyst body has a liquid-water-repellent, gas permeable polymer or organic resin coating, preferably a fluorinated olefin polymer or silicone coating, so that the isotope concentration takes place by two simultaneously occurring steps, namely, ##EQU1## WHILE THE HYDROGEN GAS FED TO THE EXCHANGE SECTION IS DERIVED IN A REACTOR VESSEL FROM LIQUID WATER THAT HAS PASSED THROUGH THE EXCHANGE SECTION.

  2. Ionic liquids as novel guests for cucurbit[6]uril in neutral water.

    PubMed

    Liu, Li; Zhao, Nan; Scherman, Oren A

    2008-03-01

    Cucurbit[6]uril was dissolved through encapsulation of an imidazolium-based ionic liquid guest in a pure water environment and the dissolution ability could be tuned by augmenting the imidazolium structure. PMID:18292893

  3. Pro-fragrant ionic liquids with stable hemiacetal motifs: water-triggered release of fragrances.

    PubMed

    Gunaratne, H Q Nimal; Nockemann, Peter; Seddon, Kenneth R

    2015-03-14

    Stable liquid and solid salts in the form of elusive hemiacetals, appended with fragrant alcohols, have been synthesised as pro-fragrances, and the controlled release of these fragrances, triggered by water, is demonstrated. PMID:25679944

  4. IDENTIFICATION OF POLAR DRINKING WATER DISINFECTION BY-PRODUCTS USING LIQUID CHROMATOGRAPHY - MASS SPECTROMETRY

    EPA Science Inventory

    A qualitative method using 2,4-dinitrophenylhydrazine (DNPH) derivatization followed by analysis with liquid chromatography (LC)/negative ion-electrospray mass spectrometry (MS) was developed for identifying polar aldehydes and ketones in ozonated drinking water. This method offe...

  5. Compact Raman Lidar Measurement of Liquid and Vapor Phase Water Under the Influence of Ionizing Radiation

    NASA Astrophysics Data System (ADS)

    Shiina, Tatsuo; Chigira, Tomoyuki; Saito, Hayato; Manago, Naohiro; Kuze, Hiroaki; Hanyu, Toshinori; Kanayama, Fumihiko; Fukushima, Mineo

    2016-06-01

    A compact Raman lidar has been developed for studying phase changes of water in the atmosphere under the influence of ionization radiation. The Raman lidar is operated at the wavelength of 349 nm and backscattered Raman signals of liquid and vapor phase water are detected at 396 and 400 nm, respectively. Alpha particles emitted from 241Am of 9 MBq ionize air molecules in a scattering chamber, and the resulting ions lead to the formation of liquid water droplets. From the analysis of Raman signal intensities, it has been found that the increase in the liquid water Raman channel is approximately 3 times as much as the decrease in the vapor phase water Raman channel, which is consistent with the theoretical prediction based on the Raman cross-sections. In addition, the radius of the water droplet is estimated to be 0.2 μm.

  6. Associations between polymorphisms of the gene and milk production traits in water buffaloes.

    PubMed

    Deng, T X; Pang, C Y; Lu, X R; Zhu, P; Duan, A Q; Liang, X W

    2016-03-01

    Signal transducer and activator of transcription 1 () is an important regulator of mammary gland differentiation and cell survival that has been regarded as a candidate gene affecting milk production traits in mammals. Therefore, this study was conducted to evaluate significant associations between SNP of the gene and milk production traits in buffaloes. Here, 18 SNP were identified in the buffalo gene, including 15 intronic mutations and 3 exon mutations. All the identified SNP were then genotyped using matrix-assisted laser desorption/ionization time of flight mass spectrometry methods from 192 buffaloes. All the SNP were in Hardy-Weinberg equilibrium, and 2 haplotype blocks were successfully constructed based on these SNP data, which formed 5 and 3 major haplotypes in the population (>5%), respectively. The results of association analysis showed that only SNP13 located in exon 10 was significantly associated with the milk production traits in the population ( < 0.05). Single nucleotide polymorphism 2, SNP5, SNP8, and SNP9 were associated with protein percentage, and SNP4 and SNP10 were associated with 305-d milk yield ( < 0.05). Our results provide evidence that polymorphisms of the buffalo gene are associated with milk production traits and can be used as a candidate gene for marker-assisted selection in buffalo breeding. PMID:27065255

  7. Ab initio calculation of the electronic absorption spectrum of liquid water

    NASA Astrophysics Data System (ADS)

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-01

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O-H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  8. Ab initio calculation of the electronic absorption spectrum of liquid water

    SciTech Connect

    Martiniano, Hugo F. M. C.; Galamba, Nuno; Cabral, Benedito J. Costa

    2014-04-28

    The electronic absorption spectrum of liquid water was investigated by coupling a one-body energy decomposition scheme to configurations generated by classical and Born-Oppenheimer Molecular Dynamics (BOMD). A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies in the liquid phase were calculated with the equation of motion coupled cluster with single and double excitations method. Molecular dynamics configurations were generated by different approaches. Classical MD were carried out with the TIP4P-Ew and AMOEBA force fields. The BLYP and BLYP-D3 exchange-correlation functionals were used in BOMD. Theoretical and experimental results for the electronic absorption spectrum of liquid water are in good agreement. Emphasis is placed on the relationship between the structure of liquid water predicted by the different models and the electronic absorption spectrum. The theoretical gas to liquid phase blue-shift of the peak positions of the electronic absorption spectrum is in good agreement with experiment. The overall shift is determined by a competition between the O–H stretching of the water monomer in liquid water that leads to a red-shift and polarization effects that induce a blue-shift. The results illustrate the importance of coupling many-body energy decomposition schemes to molecular dynamics configurations to carry out ab initio calculations of the electronic properties in liquid phase.

  9. Water-in-water emulsions stabilized by non-amphiphilic interactions: polymer-dispersed lyotropic liquid crystals.

    PubMed

    Simon, Karen A; Sejwal, Preeti; Gerecht, Ryan B; Luk, Yan-Yeung

    2007-01-30

    Emulsion systems involving surfactants are mainly driven by the separation of the hydrophobic interactions of the aliphatic chains from the hydrophilic interactions of amphiphilic molecules in water. In this study, we report an emulsion system that does not include amphiphilic molecules but molecules with functional groups that are completely solvated in water. These functional groups give rise to molecular interactions including hydrogen bonding, pi stacking, and salt bridging and are segregated into a dispersion of droplets forming a water-in-water emulsion. This water-in-water emulsion consists of dispersing droplets of a water-solvated biocompatible liquid crystal--disodium cromoglycate (DSCG)--in a continuous aqueous solution containing specific classes of water-soluble polymers. Whereas aqueous solutions of polyols support the formation of emulsions of spherical droplets consisting of lyotropic liquid crystal DSCG with long-term stability (for at least 30 days), aqueous solutions of polyamides afford droplets of DSCG in the shape of prolate ellipsoids that are stable for only 2 days. The DSCG liquid crystal in spherical droplets assumes a radial configuration in which the optical axis of the liquid crystal aligns perpendicular to the surface of the droplets but assumes a tangential configuration in prolate ellipsoids in which the optical axis of the liquid crystal aligns parallel to the surface of the droplet. Other classes of water-soluble polymers including polyethers, polycations, and polyanions do not afford a stable emulsion of DSCG droplets. Both the occurrence and the stability of this unique emulsion system can be rationalized on the basis of the functional groups of the polymer. The different configurations of the liquid crystal (DSCG) droplets were also found to correlate with the strength of the hydrogen bonding that can be formed by the functional groups on the polymer. PMID:17241072

  10. Divergent trend in density versus viscosity of ionic liquid/water mixtures: a molecular view from guanidinium ionic liquids.

    PubMed

    Singh, Akhil Pratap; Gardas, Ramesh L; Senapati, Sanjib

    2015-10-14

    Ionic liquids (ILs) have shown great potential in the dissolution and stability of biomolecules when a low-to-moderate quantity of water is added. Hence, determining the thermophysical properties and understanding these novel mixtures at the molecular level are of both fundamental and practical importance. In this context, here we report the synthesis of two nontoxic guanidinium cation based ILs, tetramethylguanidinium benzoate [TMG][BEN] and tetramethylguanidinium salicylate [TMG][SAL], and present a detailed comparison of their thermophysical properties in the presence of water. The results show that the [TMG][SAL]/water mixtures have higher density and higher apparent molar volume, but a lower viscosity and higher compressibility than the [TNG][BEN]/water mixtures. The measured viscosity and compressibility data are explained from ab initio quantum mechanical calculations and liquid-phase molecular dynamics simulations, where salicylate anions of denser [TMG][SAL]/water were found to exist as isolated ions due to intramolecular H-bonding. On the contrary, intermolecular H-bonding among the benzoate anions and their strong tendency to form an extended H-bonding network with water made [TMG][BEN]/water solutions more viscous and less compressible. This study shows the importance of probing these emerging solvents at the molecular-to-atomic level, which could be helpful in their optimal usage for task-specific applications. PMID:26347332

  11. Ice or liquid water in the Martian regolith. Morphologic indicators from rampart craters

    NASA Technical Reports Server (NTRS)

    Mouginismark, P. J.

    1987-01-01

    The morphology of ejecta blankets around certain Martian craters carries implications for volatiles in either the Martian crust or the atmosphere or both. The evidence that rampart crater ejecta can be used to infer the physical condition of volatiles in target rocks at the time of impact is reviewed. It was concluded that ice, and not liquid water, was the main volatile state, although rare examples also suggest the presence of liquid water at the time the craters were formed.

  12. Liquid-Vapor Equilibrium Isotopic Fractionation of Water. How well can classical water models predict it?

    SciTech Connect

    Chialvo, Ariel A; Horita, Juske

    2009-01-01

    The liquid-vapor equilibrium isotopic fractionation of water is determined by molecular-based simulation, via Gibbs Ensemble Monte Carlo and isothermal-isochoric molecular dynamics involving two radically different but realistic models, the extended simple point charge (SPC/E) and the Gaussian charge polarizable (GCP) models. The predicted temperature dependence of the liquid-vapor equilibrium isotopic fractionation factors for H 2 18O / H 2 16O, H 2 17O / H 2 16O, and 2H 1H 16O / 1H 2 16O are compared against the most accurate experimental datasets to assess the ability of these intermolecular potential models to describe quantum effects according to the Kirkwood-Wigner free energy perturbation ! 2 !expansion. Predictions of the vapor pressure isotopic effect for the H 2 18O / H 2 16O and H 2 17O / H 2 16O pairs are also presented in comparison with experimental data and two recently proposed thermodynamic modeling approaches. Finally, the simulation results are used to discuss some approximations behind the microscopic interpretation of isotopic fractionation based on the underlying roto-translational coupling.

  13. Void-Assisted Ion-Paired Proton Transfer at Water-Ionic Liquid Interfaces.

    PubMed

    de Eulate, Eva Alvarez; Silvester, Debbie S; Arrigan, Damien W M

    2015-12-01

    At the water-trihexyl(tetradecyl)phosphonium tris(pentafluoroethyl)trifluorophosphate ([P14,6,6,6][FAP]) ionic liquid interface, the unusual electrochemical transfer behavior of protons (H(+)) and deuterium ions (D(+)) was identified. Alkali metal cations (such as Li(+), Na(+), K(+)) did not undergo this transfer. H(+)/D(+) transfers were assisted by the hydrophobic counter anion of the ionic liquid, [FAP](-), resulting in the formation of a mixed capacitive layer from the filling of the latent voids within the anisotropic ionic liquid structure. This phenomenon could impact areas such as proton-coupled electron transfers, fuel cells, and hydrogen storage where ionic liquids are used as aprotic solvents. PMID:26489692

  14. Aquarius - A Compact and Lightweight Ice and Liquid Water Isotope Analyzer

    NASA Astrophysics Data System (ADS)

    Christensen, L. E.; Smith, M.; Chen, P.

    2008-12-01

    We are developing Aquarius, a multipurpose ice and liquid water isotope analyzer. Aquarius combines a liquid-to-gas converter with a laser spectrometer to measure water isotopologue abundances with per mil accuracy. Its compact size will be ideal for field hydrology, while an optional interface with a thermal ice drill will enable in situ measurement of polar climate records. Upon completion, Aquarius will be used for extraterrestrial studies including identifying Mars" past climate cycles, tracing Martian water history, and measuring deuterium abundance in the primordial solar system as recorded in comet ice. Anticipated terrestrial applications include sampling aquifers to assess drinking water quality in developing countries.

  15. Polymer formulation for removing hydrogen and liquid water from an enclosed space

    DOEpatents

    Shepodd, Timothy J.

    2006-02-21

    This invention describes a solution to the particular problem of liquid water formation in hydrogen getters exposed to quantities of oxygen. Water formation is usually desired because the recombination reaction removes hydrogen without affecting gettering capacity and the oxygen removal reduces the chances for a hydrogen explosion once free oxygen is essentially removed. The present invention describes a getter incorporating a polyacrylate compound that can absorb up to 500% of its own weight in liquid water without significantly affecting its hydrogen gettering/recombination properties, but that also is insensitive to water vapor.

  16. Water permeability of primary mouse keratinocyte cultures grown at the air-liquid interface

    SciTech Connect

    Cumpstone, M.B.; Kennedy, A.H.; Harmon, C.S.; Potts, R.O.

    1989-04-01

    In order to study the development of the epidermal permeability barrier in vitro, tritiated water (HTO) flux was measured across murine keratinocytes cultured at the air-liquid interface. Using a micro-diffusion technique, it was shown that air-liquid cultures form areas where the water diffusion is comparable to that of intact neonatal mouse skin. When water permeability is measured over a large area of the culture surface, however, significantly higher flux is obtained. These results show that under the culture conditions used, areas of water barrier comparable to intact neonatal mouse skin coexist with regions of less complete barrier formation.

  17. Pressure Effect on the Boson Peak in Deeply Cooled Confined Water: Evidence of a Liquid-Liquid Transition

    DOE PAGESBeta

    Wang, Zhe; Kolesnikov, Alexander I.; Ito, Kanae; Podlesnyak, Andrey; Chen, Sow-Hsin

    2015-12-03

    We studied the boson peak in deeply cooled water confined in nanopores in order to examine the liquid-liquid transition (LLT). Below ~180 K, the boson peaks at pressures P higher than ~3.5 kbar are evidently distinct from those at low pressures by higher mean frequencies and lower heights. Moreover, the higher-P boson peaks can be rescaled to a master curve while the lower-P boson peaks can be rescaled to a different one. Moreover, these phenomena agree with the existence of two liquid phases with different densities and local structures and the associated LLT in the measured (P, T) region. Additionally,more » the P dependence of the librational band also agrees with the above conclusion.« less

  18. Pressure Effect on the Boson Peak in Deeply Cooled Confined Water: Evidence of a Liquid-Liquid Transition

    SciTech Connect

    Wang, Zhe; Kolesnikov, Alexander I.; Ito, Kanae; Podlesnyak, Andrey; Chen, Sow-Hsin

    2015-12-03

    We studied the boson peak in deeply cooled water confined in nanopores in order to examine the liquid-liquid transition (LLT). Below ~180 K, the boson peaks at pressures P higher than ~3.5 kbar are evidently distinct from those at low pressures by higher mean frequencies and lower heights. Moreover, the higher-P boson peaks can be rescaled to a master curve while the lower-P boson peaks can be rescaled to a different one. Moreover, these phenomena agree with the existence of two liquid phases with different densities and local structures and the associated LLT in the measured (P, T) region. Additionally, the P dependence of the librational band also agrees with the above conclusion.

  19. The vibrational spectrum of water in liquid alkanes.

    PubMed Central

    Conrad, M P; Strauss, H L

    1985-01-01

    The water wire hypothesis of hydrogen-ion transport in lipid bilayers has prompted a search for water aggregates in bulk hydrocarbons. The asymmetric stretching vibration of the water dissolved in n-decane and in a number of other alkanes and alkenes has been observed. The water band in the alkanes is very wide and fits to the results of a J-diffusion calculation for the water rotation. This implies that the water is freely rotating between collisions with the solvent and certainly not hydrogen bonded to anything. The existence of water aggregates is thus most unlikely. In contrast, water in an alkene is hydrogen bonded to the solvent molecules (although not to other water molecules) and shows an entirely different spectrum. PMID:4016205

  20. Liquid water absorption and scattering effects in DOAS retrievals over oceans

    NASA Astrophysics Data System (ADS)

    Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

    2014-05-01

    It is well-known that spectral effects of liquid water are present in absorption (DOAS) measurements above the ocean and insufficiently removed liquid water structures may interfere with trace gas absorptions leading to wrong (sometimes even non-physical) results. Currently available literature cross-sections of liquid water absorption are provided in coarser resolution than hyperspectral DOAS applications require and Vibrational Raman Scattering (VRS) is mostly unconsidered or compensated for using simulated pseudo cross-sections from radiative transfer modelling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS measurements were performed into very clear natural waters achieving underwater light paths of up to 50 m. From these measurements, the retrieval of a residual (H2Ores) spectrum is presented compensating simultaneously for insufficiencies of the liquid water absorption cross-section and broad-banded VRS structures. Small-banded (Ring) structures caused by VRS were found to be very efficiently compensated for by the intensity offset (straylight) correction included in the DOAS fit. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality. This was not achieved using a liquid water cross-section in combination with a simulated VRS spectrum. Typical values of improvement depend on the measurement's contamination with liquid water structures and range from ≈ 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ores spectrum was found to prevent misfits of NO2 slant columns especially for very low NO2 scenarios and thus increase the reliability of the fit. In test fits on OMI satellite data, the H2Ores spectrum was found selectively above ocean surfaces where it leads to fit quality improvements of up to 6-18%.

  1. Experimentally probing the libration of interfacial water: the rotational potential of water is stiffer at the air/water interface than in bulk liquid.

    PubMed

    Tong, Yujin; Kampfrath, Tobias; Campen, R Kramer

    2016-07-21

    Most properties of liquid water are determined by its hydrogen-bond network. Because forming an aqueous interface requires termination of this network, one might expect the molecular level properties of interfacial water to markedly differ from water in bulk. Intriguingly, much prior experimental and theoretical work has found that, from the perspective of their time-averaged structure and picosecond structural dynamics, hydrogen-bonded OH groups at an air/water interface behave the same as hydrogen-bonded OH groups in bulk liquid water. Here we report the first experimental observation of interfacial water's libration (i.e. frustrated rotation) using the laser-based technique vibrational sum frequency spectroscopy. We find this mode has a frequency of 834 cm(-1), ≈165 cm(-1) higher than in bulk liquid water at the same temperature and similar to bulk ice. Because libration frequency is proportional to the stiffness of water's rotational potential, this increase suggests that one effect of terminating bulk water's hydrogen bonding network at the air/water interface is retarding rotation of water around intact hydrogen bonds. Because in bulk liquid water the libration plays a key role in stabilizing reaction intermediates and dissipating excess vibrational energy, we expect the ability to probe this mode in interfacial water to open new perspectives on the kinetics of heterogeneous reactions at aqueous interfaces. PMID:27339861

  2. Magnetic retrieval of ionic liquids: fast dispersive liquid-liquid microextraction for the determination of benzoylurea insecticides in environmental water samples.

    PubMed

    Zhang, Jiaheng; Li, Min; Yang, Miyi; Peng, Bing; Li, Yubo; Zhou, Wenfeng; Gao, Haixiang; Lu, Runhua

    2012-09-01

    A novel, rapid ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) technique combined with magnetic retrieval (MR-IL-DLLME) has been developed and used to analyze five benzoylurea insecticides (BUs) in environmental water samples. This procedure was based on the magnetic retrieval of the ionic liquid using unmodified magnetic nanoparticles (MNPs). In this experiment, the fine ionic liquid droplets formed in aqueous samples functioned as an extractant for the extraction of BUs; after the extraction process was completed, Fe₃O₄ MNPs were added as a carrier to retrieve and separate the ionic liquid from the sample solution. After the supernatant was removed, the ionic liquid was desorbed using acetonitrile and subsequently injected directly into an HPLC system for analysis. The optimum experimental parameters are as follows: 20 mg of Fe₃O₄ (20 nm) as magnetic sorbents; 70 μL of [C₆MIM][PF₆] as the extraction solvent; 300 μL of acetonitrile as the disperser solvent; a vortex extraction time of 90 s with the vortex agitator set at 2800 rpm and no ionic strength. Under the optimized conditions, good linearity was obtained with correlation coefficients (r) greater than 0.9981. The repeatability and reproducibility of the proposed method were found to be good, and the limits of detection ranged from 0.05 μg L⁻¹ to 0.15 μg L⁻¹. The proposed method was then successfully used for the rapid determination of BUs in real water samples. The recoveries of five BUs at two spiked levels ranged from 79.8 to 91.7% with RSDs less than 6.0%. PMID:22871379

  3. Density fluctuations and dielectric constant of water in low and high density liquid states

    NASA Astrophysics Data System (ADS)

    Lascaris, Erik; Zhang, Cui; Galli, Giulia A.; Franzese, Giancarlo; Stanley, H. Eugene

    2012-02-01

    The hypothesis of a liquid-liquid critical point (LLCP) in the phase diagram of water, though first published many years ago, still remains the subject of a heated debate. According to this hypothesis there exists a critical point near T 244 K, and P 215 MPa, located at the end of a coexistence line between a high density liquid (HDL) and a low density liquid state (LDL). The LLCP lies below the homogenous nucleation temperature of water and it has so far remained inaccessible to experiments. We study a model of water exhibiting a liquid-liquid phase transition (that is a liquid interacting through the ST2 potential) and investigate the properties of dipolar fluctuations as a function of density, in the HDL and LDL. We find an interesting correlation between the macroscopic dielectric constants and the densities of the two liquids in the vicinity of the critical point, and we discuss possible implications for measurements close to the region where the LLCP may be located.

  4. Simulation of water vapor condensation on LOX droplet surface using liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Powell, Eugene A.

    1988-01-01

    The formation of ice or water layers on liquid oxygen (LOX) droplets in the Space Shuttle Main Engine (SSME) environment was investigated. Formulation of such ice/water layers is indicated by phase-equilibrium considerations under conditions of high partial pressure of water vapor (steam) and low LOX droplet temperature prevailing in the SSME preburner or main chamber. An experimental investigation was begun using liquid nitrogen as a LOX simulant. A monodisperse liquid nitrogen droplet generator was developed which uses an acoustic driver to force the stream of liquid emerging from a capillary tube to break up into a stream of regularly space uniformly sized spherical droplets. The atmospheric pressure liquid nitrogen in the droplet generator reservoir was cooled below its boiling point to prevent two phase flow from occurring in the capillary tube. An existing steam chamber was modified for injection of liquid nitrogen droplets into atmospheric pressure superheated steam. The droplets were imaged using a stroboscopic video system and a laser shadowgraphy system. Several tests were conducted in which liquid nitrogen droplets were injected into the steam chamber. Under conditions of periodic droplet formation, images of 600 micron diameter liquid nitrogen droplets were obtained with the stroboscopic video systems.

  5. Case Studies of Water Vapor and Surface Liquid Water from AVIRIS Data Measured Over Denver, CO and Death Valley, CA

    NASA Technical Reports Server (NTRS)

    Gao, B.-C.; Kierein-Young, K. S.; Goetz, A. F. H.; Westwater, E. R.; Stankov, B. B.; Birkenheuer, D.

    1991-01-01

    High spatial resolution column atmospheric water vapor amounts and equivalent liquid water thicknesses of surface targets are retrieved from spectral data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The retrievals are made using a nonlinear least squares curve fitting technique. Two case studies from AVIRIS data acquired over Denver-Platteville area, Colorado and over Death Valley, California are presented. The column water vapor values derived from AVIRIS data over the Denver-Platteville area are compared with those obtained from radiosondes, ground level upward-looking microwave radiometers, and geostationary satellite measurements. The column water vapor image shows spatial variation patterns related to the passage of a weather front system. The column water vapor amounts derived from AVIRIS data over Death Valley decrease with increasing surface elevation. The derived liquid water image clearly shows surface drainage patterns.

  6. Cold crystallisation behaviour of water molecules in ionic liquids as a screening method to evaluate biocompatibility of the hydrated ionic liquids.

    PubMed

    Fujita, Kyoko; Nikawa, Yohsuke; Ohno, Hiroyuki

    2013-04-21

    Hydrated ionic liquids, exhibiting cold crystallisation behaviour of water molecules in a certain range of water contents, successfully dissolved cytochrome c maintaining the original spin state of heme. PMID:23486783

  7. Review of the methods to form hydrogen peroxide in electrical discharge plasma with liquid water

    NASA Astrophysics Data System (ADS)

    Locke, Bruce R.; Shih, Kai-Yuan

    2011-06-01

    This paper presents a review of the literature dealing with the formation of hydrogen peroxide from plasma processes. Energy yields for hydrogen peroxide generation by plasma from water span approximately three orders of magnitude from 4 × 10-2 to 80 g kWh-1. A wide range of plasma processes from rf to pulsed, ac, and dc discharges directly in the liquid phase have similar energy yields and may thus be limited by radical quenching processes at the plasma-liquid interface. Reactor modification using discharges in bubbles and discharges over the liquid phase can provide modest improvements in energy yield over direct discharge in the liquid, but the interpretation is complicated by additional chemical reactions of gas phase components such as ozone and nitrogen oxides. The highest efficiency plasma process utilizes liquid water droplets that may enhance efficiency by sequestering hydrogen peroxide in the liquid and by suppressing decomposition reactions by radicals from the gas and at the interface. Kinetic simulations of water vapor reported in the literature suggest that plasma generation of hydrogen peroxide should approach 45% of the thermodynamics limit, and this fact coupled with experimental studies demonstrating improvements with the presence of the condensed liquid phase suggest that further improvements in energy yield may be possible. Plasma generation of hydrogen peroxide directly from water compares favorably with a number of other methods including electron beam, ultrasound, electrochemical and photochemical methods, and other chemical processes.

  8. Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water

    PubMed Central

    Zhao, Li-Shan; Cao, Ze-Xian; Wang, Qiang

    2015-01-01

    Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, . Here we report a universal water-content, , dependence of for aqueous solutions. Solutions with vitrify/devitrify at a constant temperature, , referring to freeze-concentrated phase with left behind ice crystallization. Those solutions with totally vitrify at under conventional cooling/heating process though, of the samples annealed at temperatures   to effectively evoke ice recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of by annealing is attributable to freeze-concentrated phase of solutions instead of ‘liquid II phase of water’. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution. PMID:26503911

  9. Two-Phase Model of Liquid-Liquid Interactions With Interface Capturing: Application to Water Assisted Injection Molding

    NASA Astrophysics Data System (ADS)

    Silva, Luisa; Lanrivain, Rodolphe; Zerguine, Walid; Rodriguez-Villa, Andrès; Coupez, Thierry

    2007-05-01

    In this paper, a two phase model to compute liquid-liquid flows is presented. We consider that one phase is a highly viscous thermodependent liquid (polymer phase), whereas the second one is a low viscosity low temperature fluid (water). The first part of this paper concerns capture of the interface between the water and the polymer (or determination of the phase field function). Classical VOF and Level set techniques have been implemented and were ameliorated using mesh adaptation techniques. To accurately determine the velocity field, a two-phase formulation is considered, based in the theory of mixtures, and we introduce a scalar parameter, the phase fraction quantifying the presence of each phase in each point of the computational domain. A friction type coupling between both phases is retained. Using the mixed finite element method within an eulerian framework, we calculate in a single system the whole kinematic variables for both liquids (velocity and pressure of each phase). Results are shown, for 2D and 3D parts.

  10. Distribution of aquifers, liquid-waste impoundments, and municipal water-supply sources, Massachusetts

    USGS Publications Warehouse

    Delaney, David F.; Maevsky, Anthony

    1980-01-01

    Impoundments of liquid waste are potential sources of ground-water contamination in Massachusetts. The map report, at a scale of 1 inch equals 4 miles, shows the idstribution of aquifers and the locations of municipal water-supply sources and known liquid-waste impoundments. Ground water, an important source of municipal water supply, is produced from shallow sand and gravel aquifers that are generally unconfined, less than 200 feet thick, and yield less than 2,000 gallons per minute to individual wells. These aquifers commonly occupy lowlands and stream valleys and are most extensive in eastern Massachusetts. Surface impoundments of liquid waste are commonly located over these aquifers. These impoundments may leak and allow waste to infiltrate underlying aquifers and alter their water quality. (USGS)

  11. Dielectric spectroscopy: a technique for the determination of water coordination within ionic liquids.

    PubMed

    Dimitrakis, Georgios; Villar-Garcia, Ignacio J; Lester, Edward; Licence, Peter; Kingman, Samuel

    2008-05-28

    The presence of water can have a significant influence upon both the physical and dielectric properties of ionic liquids and consequently their ability to interact with microwaves. Herein we show that complex permittivity initially decreases as low concentrations of water are added to the system, the continued addition of water gives rise to an inversion in this trend. We propose that this minimum point may be used to identify water dimer formation. PMID:18473042

  12. Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.

    SciTech Connect

    Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz; Prausnitz, John M.

    2007-06-25

    Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic liquids containing octylpyridinium cations are very good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. Such liquids containing a disulfide functional group are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.

  13. Semiquantum molecular dynamics simulation of liquid water by time-dependent Hartree approach.

    PubMed

    Kim, Hyeon-Deuk; Ando, Koji

    2009-08-14

    Semiquantum liquid water molecular dynamics simulation was developed using the time-dependent Hartree approach. The classical intra- and intermolecular potential functions of water were extended to describe the wave packet (WP) hydrogen atoms. The equations of motion with an extended phase space including auxiliary coordinates and momenta representing the hydrogen WP widths were derived and solved. The molecular dynamics simulation of semiquantum water demonstrated that the semiquantum hydrogen atoms make the liquid water less structured and the hydrogen bonds weakened. The poor structurization in liquid water was inferred from the increased mobility of a water molecule and the redshift of OH stretching frequency. The zero-point energy introduced by the semiquantum hydrogens enhances the anharmonic potential effects and contributes to the redshifted OH stretching vibration. We found a significant peak around 4400 cm(-1) in the absorption spectrum resulting from the energy exchange between the WP width dynamics and the coupling of the OH stretching mode and the rotational motion of each water. We proposed that a liquid free energy landscape is smoothed due to semiquantum hydrogen atoms, and influences the liquid structure and dynamics. PMID:19691391

  14. Screen-printed electrode based electrochemical detector coupled with ionic liquid dispersive liquid-liquid microextraction and microvolume back-extraction for determination of mercury in water samples.

    PubMed

    Fernández, Elena; Vidal, Lorena; Martín-Yerga, Daniel; Blanco, María del Carmen; Canals, Antonio; Costa-García, Agustín

    2015-04-01

    A novel approach is presented, whereby gold nanostructured screen-printed carbon electrodes (SPCnAuEs) are combined with in-situ ionic liquid formation dispersive liquid-liquid microextraction (in-situ IL-DLLME) and microvolume back-extraction for the determination of mercury in water samples. In-situ IL-DLLME is based on a simple metathesis reaction between a water-miscible IL and a salt to form a water-immiscible IL into sample solution. Mercury complex with ammonium pyrrolidinedithiocarbamate is extracted from sample solution into the water-immiscible IL formed in-situ. Then, an ultrasound-assisted procedure is employed to back-extract the mercury into 10 µL of a 4 M HCl aqueous solution, which is finally analyzed using SPCnAuEs. Sample preparation methodology was optimized using a multivariate optimization strategy. Under optimized conditions, a linear range between 0.5 and 10 µg L(-1) was obtained with a correlation coefficient of 0.997 for six calibration points. The limit of detection obtained was 0.2 µg L(-1), which is lower than the threshold value established by the Environmental Protection Agency and European Union (i.e., 2 µg L(-1) and 1 µg L(-1), respectively). The repeatability of the proposed method was evaluated at two different spiking levels (3 and 10 µg L(-1)) and a coefficient of variation of 13% was obtained in both cases. The performance of the proposed methodology was evaluated in real-world water samples including tap water, bottled water, river water and industrial wastewater. Relative recoveries between 95% and 108% were obtained. PMID:25640123

  15. Liquid Water Cloud Measurements Using the Raman Lidar Technique: Current Understanding and Future Research Needs

    NASA Technical Reports Server (NTRS)

    Tetsu, Sakai; Whiteman, David N.; Russo, Felicita; Turner, David D.; Veselovskii, Igor; Melfi, S. Harvey; Nagai, Tomohiro; Mano, Yuzo

    2013-01-01

    This paper describes recent work in the Raman lidar liquid water cloud measurement technique. The range-resolved spectral measurements at the National Aeronautics and Space Administration Goddard Space Flight Center indicate that the Raman backscattering spectra measured in and below low clouds agree well with theoretical spectra for vapor and liquid water. The calibration coefficients of the liquid water measurement for the Raman lidar at the Atmospheric Radiation Measurement Program Southern Great Plains site of the U.S. Department of Energy were determined by comparison with the liquid water path (LWP) obtained with Atmospheric Emitted Radiance Interferometer (AERI) and the liquid water content (LWC) obtained with the millimeter wavelength cloud radar and water vapor radiometer (MMCR-WVR) together. These comparisons were used to estimate the Raman liquid water cross-sectional value. The results indicate a bias consistent with an effective liquid water Raman cross-sectional value that is 28%-46% lower than published, which may be explained by the fact that the difference in the detectors' sensitivity has not been accounted for. The LWP of a thin altostratus cloud showed good qualitative agreement between lidar retrievals and AERI. However, the overall ensemble of comparisons of LWP showed considerable scatter, possibly because of the different fields of view of the instruments, the 350-m distance between the instruments, and the horizontal inhomogeneity of the clouds. The LWC profiles for a thick stratus cloud showed agreement between lidar retrievals andMMCR-WVR between the cloud base and 150m above that where the optical depth was less than 3. Areas requiring further research in this technique are discussed.

  16. Drilling to Extract Liquid Water on Mars: Feasible and Worth the Investment

    NASA Technical Reports Server (NTRS)

    Stoker, C.

    2004-01-01

    A critical application for the success of the Exploration Mission is developing cost effective means to extract resources from the Moon and Mars needed to support human exploration. Water is the most important resource in this regard, providing a critical life support consumable, the starting product of energy rich propellants, energy storage media (e.g. fuel cells), and a reagent used in virtually all manufacturing processes. Water is adsorbed and chemically bound in Mars soils, ice is present near the Martian surface at high latitudes, and water vapor is a minor atmospheric constituent, but extracting meaningful quantities requires large complex mechanical systems, massive feedstock handling, and large energy inputs. Liquid water aquifers are almost certain to be found at a depth of several kilometers on Mars based on our understanding of the average subsurface thermal gradient, and geological evidence from recent Mars missions suggests liquid water may be present much closer to the surface at some locations. The discovery of hundreds of recent water-carved gullies on Mars indicates liquid water can be found at depths of 200-500 meters in many locations. Drilling to obtain liquid water via pumping is therefore feasible and could lower the cost and improve the return of Mars exploration more than any other ISRU technology on the horizon. On the Moon, water ice may be found in quantity in permanently shadowed regions near the poles.

  17. Effect of water presence on choline chloride-2urea ionic liquid and coating platings from the hydrated ionic liquid

    NASA Astrophysics Data System (ADS)

    Du, Cuiling; Zhao, Binyuan; Chen, Xiao-Bo; Birbilis, Nick; Yang, Haiyan

    2016-07-01

    In the present study, hygroscopicity of the choline chloride-urea (ChCl-2Urea) ionic liquid (IL) was confirmed through Karl-Fisher titration examination, indicating that the water content in the hydrated ChCl-2Urea IL was exposure-time dependent and could be tailored by simple heating treatment. The impact of the absorbed water on the properties of ChCl-2Urea IL, including viscosity, electrical conductivity, electrochemical window and chemical structure was investigated. The results show that water was able to dramatically reduce the viscosity and improve the conductivity, however, a broad electrochemical window could be persisted when the water content was below ~6 wt.%. These characteristics were beneficial for producing dense and compact coatings. Nickel (Ni) coatings plating from hydrated ChCl-2Urea IL, which was selected as an example to show the effect of water on the electroplating, displayed that a compact and corrosion-resistant Ni coating was plated from ChCl-2Urea IL containing 6 wt.% water doped with 400 mg/L NA at a moderate temperature. As verified by FTIR analysis, the intrinsic reason could be ascribed that water was likely linked with urea through strong hydrogen bond so that the water decomposition was suppressed during plating. Present study may provide a reference to prepare some similar water-stable ILs for plating.

  18. Effect of water presence on choline chloride-2urea ionic liquid and coating platings from the hydrated ionic liquid

    PubMed Central

    Du, Cuiling; Zhao, Binyuan; Chen, Xiao-Bo; Birbilis, Nick; Yang, Haiyan

    2016-01-01

    In the present study, hygroscopicity of the choline chloride-urea (ChCl-2Urea) ionic liquid (IL) was confirmed through Karl-Fisher titration examination, indicating that the water content in the hydrated ChCl-2Urea IL was exposure-time dependent and could be tailored by simple heating treatment. The impact of the absorbed water on the properties of ChCl-2Urea IL, including viscosity, electrical conductivity, electrochemical window and chemical structure was investigated. The results show that water was able to dramatically reduce the viscosity and improve the conductivity, however, a broad electrochemical window could be persisted when the water content was below ~6 wt.%. These characteristics were beneficial for producing dense and compact coatings. Nickel (Ni) coatings plating from hydrated ChCl-2Urea IL, which was selected as an example to show the effect of water on the electroplating, displayed that a compact and corrosion-resistant Ni coating was plated from ChCl-2Urea IL containing 6 wt.% water doped with 400 mg/L NA at a moderate temperature. As verified by FTIR analysis, the intrinsic reason could be ascribed that water was likely linked with urea through strong hydrogen bond so that the water decomposition was suppressed during plating. Present study may provide a reference to prepare some similar water-stable ILs for plating. PMID:27381851

  19. Effect of water presence on choline chloride-2urea ionic liquid and coating platings from the hydrated ionic liquid.

    PubMed

    Du, Cuiling; Zhao, Binyuan; Chen, Xiao-Bo; Birbilis, Nick; Yang, Haiyan

    2016-01-01

    In the present study, hygroscopicity of the choline chloride-urea (ChCl-2Urea) ionic liquid (IL) was confirmed through Karl-Fisher titration examination, indicating that the water content in the hydrated ChCl-2Urea IL was exposure-time dependent and could be tailored by simple heating treatment. The impact of the absorbed water on the properties of ChCl-2Urea IL, including viscosity, electrical conductivity, electrochemical window and chemical structure was investigated. The results show that water was able to dramatically reduce the viscosity and improve the conductivity, however, a broad electrochemical window could be persisted when the water content was below ~6 wt.%. These characteristics were beneficial for producing dense and compact coatings. Nickel (Ni) coatings plating from hydrated ChCl-2Urea IL, which was selected as an example to show the effect of water on the electroplating, displayed that a compact and corrosion-resistant Ni coating was plated from ChCl-2Urea IL containing 6 wt.% water doped with 400 mg/L NA at a moderate temperature. As verified by FTIR analysis, the intrinsic reason could be ascribed that water was likely linked with urea through strong hydrogen bond so that the water decomposition was suppressed during plating. Present study may provide a reference to prepare some similar water-stable ILs for plating. PMID:27381851

  20. Low cost methodology for estrogens monitoring in water samples using dispersive liquid-liquid microextraction and HPLC with fluorescence detection.

    PubMed

    Lima, Diana L D; Silva, Carla Patrícia; Otero, Marta; Esteves, Valdemar I

    2013-10-15

    A new low cost methodology for estrogens' analysis in water samples was developed in this work. Based on dispersive liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection, the developed method is fast, cheap, easy-to-use, uses low volumes of organic solvents and has the possibility of a large number of samples to be extracted in parallel. Under optimum conditions (sample volume: 8 mL; extraction solvent: 200 μL of chlorobenzene; dispersive solvent: 2000 μL of acetone), the enrichment factor and extraction recoveries were 145 and 72% for 17β-estradiol (E2) and 178 and 89% for 17α-ethinylestradiol (EE2), respectively. Limits of detection of 2.0 ng L(-1) for E2 and 6.5 ng L(-1) for EE2 were achieved, allowing the detection and quantification of these compounds in surface and waste water samples with concentrations from 12 to 32 ng L(-1) for E2 and from 11 to 18 ng L(-1) for EE2. Also, recovery tests were performed to evaluate possible matrix effects. Recoveries between 98% and 106% were obtained using humic acids (HA) to simulate the effect of organic matter, and between 86% and 120% in real water samples. PMID:24054691

  1. Use of magnetic effervescent tablet-assisted ionic liquid dispersive liquid-liquid microextraction to extract fungicides from environmental waters with the aid of experimental design methodology.

    PubMed

    Yang, Miyi; Wu, Xiaoling; Jia, Yuhan; Xi, Xuefei; Yang, Xiaoling; Lu, Runhua; Zhang, Sanbing; Gao, Haixiang; Zhou, Wenfeng

    2016-02-01

    In this work, a novel effervescence-assisted microextraction technique was proposed for the detection of four fungicides. This method combines ionic liquid-based dispersive liquid-liquid microextraction with the magnetic retrieval of the extractant. A magnetic effervescent tablet composed of Fe3O4 magnetic nanoparticles, sodium carbonate, sodium dihydrogen phosphate and 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonimide) was used for extractant dispersion and retrieval. The main factors affecting the extraction efficiency were screened by a Plackett-Burman design and optimized by a central composite design. Under the optimum conditions, good linearity was obtained for all analytes in pure water model and real water samples. Just for the pure water, the recoveries were between 84.6% and 112.8%, the limits of detection were between 0.02 and 0.10 μg L(-1) and the intra-day precision and inter-day precision both are lower than 4.9%. This optimized method was successfully applied in the analysis of four fungicides (azoxystrobin, triazolone, cyprodinil, trifloxystrobin) in environmental water samples and the recoveries ranged between 70.7% and 105%. The procedure promising to be a time-saving, environmentally friendly, and efficient field sampling technique. PMID:26772131

  2. Ionic liquid-based dispersive liquid-liquid microextraction and enhanced spectrophotometric determination of molybdenum (VI) in water and plant leaves samples by FO-LADS.

    PubMed

    Gharehbaghi, Maysam; Shemirani, Farzaneh

    2011-02-01

    A new simple and rapid ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) has been applied to preconcentrate trace levels of molybdenum (VI) as a prior step to its enhanced determination by fiber optic-linear array detection spectrophotometry (FO-LADS). In this method, a small amount of [Hmim][Tf(2)N] (1-hexyl-3-methylimmidazolium bis (trifluormethylsulfonyl) imid) as an extraction solvent was applied to extract molybdenum - pyrogallol red complex, which was formed in an aqueous solution in the presence of N-cetyl-N-N-N-trimethyl ammonium chloride as a sensitizing agent. Under optimum conditions, enhancement factor, detection limit and relative standard deviation (n=5, for 30 μg L(-1) of molybdenum (VI)) in 10 mL water sample were 72.6, 1.43 μg L(-1) and 2.8%, respectively. PMID:21092750

  3. Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry for a sensitive determination of cadmium in water samples

    NASA Astrophysics Data System (ADS)

    Li, Shengqing; Cai, Shun; Hu, Wei; Chen, Hao; Liu, Hanlan

    2009-07-01

    A new method was developed for the determination of cadmium in water samples using ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-based USA-DLLME) followed by electrothermal atomic absorption spectrometry (ETAAS). The IL-based USA-DLLME procedure is free of volatile organic solvents, and there is no need for a dispersive solvent, in contrast to conventional DLLME. The ionic liquid, 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF 6), was quickly disrupted by an ultrasonic probe for 1 min and dispersed in water samples like a cloud. At this stage, a hydrophobic cadmium-DDTC complex was formed and extracted into the fine droplets of HMIMPF 6. After centrifugation, the concentration of the enriched cadmium in the sedimented phase was determined by ETAAS. Some effective parameters of the complex formation and microextraction, such as the concentration of the chelating agent, the pH, the volume of the extraction solvent, the extraction time, and the salt effect, have been optimized. Under optimal conditions, a high extraction efficiency and selectivity were reached for the extraction of 1.0 ng of cadmium in 10.0 mL of water solution employing 73 µL of HMIMPF 6 as the extraction solvent. The enrichment factor of the method is 67. The detection limit was 7.4 ng L - 1 , and the characteristic mass ( m0, 0.0044 absorbance) of the proposed method was 0.02 pg for cadmium (Cd). The relative standard deviation (RSD) for 11 replicates of 50 ng L - 1 Cd was 3.3%. The method was applied to the analysis of tap, well, river, and lake water samples and the Environmental Water Reference Material GSBZ 50009-88 (200921). The recoveries of spiked samples were in the range of 87.2-106%.

  4. A new dispersive liquid-liquid microextraction using ionic liquid based microemulsion coupled with cloud point extraction for determination of copper in serum and water samples.

    PubMed

    Arain, Salma Aslam; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Mariam Shahzadi; Panhwar, Abdul Haleem; Khan, Naeemullah; Baig, Jameel Ahmed; Shah, Faheem

    2016-04-01

    A simple and rapid dispersive liquid-liquid microextraction procedure based on ionic liquid assisted microemulsion (IL-µE-DLLME) combined with cloud point extraction has been developed for preconcentration copper (Cu(2+)) in drinking water and serum samples of adolescent female hepatitits C (HCV) patients. In this method a ternary system was developed to form microemulsion (µE) by phase inversion method (PIM), using ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) and nonionic surfactant, TX-100 (as a stabilizer in aqueous media). The Ionic liquid microemulsion (IL-µE) was evaluated through visual assessment, optical light microscope and spectrophotometrically. The Cu(2+) in real water and aqueous acid digested serum samples were complexed with 8-hydroxyquinoline (oxine) and extracted into IL-µE medium. The phase separation of stable IL-µE was carried out by the micellar cloud point extraction approach. The influence of of different parameters such as pH, oxine concentration, centrifugation time and rate were investigated. At optimized experimental conditions, the limit of detection and enhancement factor were found to be 0.132 µg/L and 70 respectively, with relative standard deviation <5%. In order to validate the developed method, certified reference materials (SLRS-4 Riverine water) and human serum (Sero-M10181) were analyzed. The resulting data indicated a non-significant difference in obtained and certified values of Cu(2+). The developed procedure was successfully applied for the preconcentration and determination of trace levels of Cu(2+) in environmental and biological samples. PMID:26761783

  5. Formation of Martian Gullies by the Flow of Simultaneously Freezing and Boiling Liquid Water

    NASA Technical Reports Server (NTRS)

    Heldmann, Jennifer L.; Mellon, Michael T.; Toon, Owen B.; Pollard, Wayne H.; Mellon, Michael T.; Pitlick, John; McKay, Christopher P.; Andersen, Dale T.

    2004-01-01

    Geomorphic evidence suggests that recent gullies on Mars were formed by fluvial activity. The Martian gully features are significant because their existence implies the presence of liquid water near the surface on Mars in geologically recent times. Irrespective of the ultimate source of the fluid carving the gullies, we seek to understand the behavior of this fluid after it reaches the Martian surface. We find that, contrary to popular belief, the fluvially-carved Martian gullies require formation conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water. Mars Global Surveyor observations of gully length and our modeling of water stability are consistent with gully formation from the action of pure liquid water that is simultaneously boiling and freezing.

  6. Dosimetric characterization of a {sup 131}Cs brachytherapy source by thermoluminescence dosimetry in liquid water

    SciTech Connect

    Tailor, Ramesh; Ibbott, Geoffrey; Lampe, Stephanie; Bivens Warren, Whitney; Tolani, Naresh

    2008-12-15

    Dosimetry measurements of a {sup 131}Cs brachytherapy source have been performed in liquid water employing thermoluminescence dosimeters. A search of the literature reveals that this is the first time a complete set of dosimetric parameters for a brachytherapy ''seed'' source has been measured in liquid water. This method avoids the medium correction uncertainties introduced by the use of water-equivalent plastic phantoms. To assure confidence in the results, four different sources were employed for each parameter measured, and measurements were performed multiple times. The measured dosimetric parameters presented here are based on the AAPM Task Group 43 formalism. The dose-rate constant measured in liquid water was (1.063{+-}0.023) cGy h{sup -1} U{sup -1} and was based on the air-kerma strength standard for this source established by the National Institute of Standards and Technology. Measured values for the 2D anisotropy function and the radial dose function are presented.

  7. Mesoscopic modeling of liquid water transport in polymer electrolyte fuel cells

    SciTech Connect

    Mukherjee, Partha P; Wang, Chao Yang

    2008-01-01

    A key performance limitation in polymer electrolyte fuel cells (PEFC), manifested in terms of mass transport loss, originates from liquid water transport and resulting flooding phenomena in the constituent components. Liquid water leads to the coverage of the electrochemically active sites in the catalyst layer (CL) rendering reduced catalytic activity and blockage of the available pore space in the porous CL and fibrous gas diffusion layer (GDL) resulting in hindered oxygen transport to the active reaction sites. The cathode CL and the GDL therefore playa major role in the mass transport loss and hence in the water management of a PEFC. In this article, we present the development of a mesoscopic modeling formalism coupled with realistic microstructural delineation to study the profound influence of the pore structure and surface wettability on liquid water transport and interfacial dynamics in the PEFC catalyst layer and gas diffusion layer.

  8. Photoelectron spectroscopy of liquid water, some alcohols, and pure nonane in free micro jets

    NASA Astrophysics Data System (ADS)

    Faubel, Manfred; Steiner, Björn; Toennies, J. Peter

    1997-06-01

    The recently developed technique of accessing volatile liquids in a high vacuum environment by using a very thin liquid jet is implemented to carry out the first measurements of photoelectron spectra of pure liquid water, methanol, ethanol, 1-propanol, 1-butanol, and benzyl alcohol as well as of liquid n-nonane. The apparatus, which consists of a commercial hemispherical (10 cm mean radius) electron analyzer and a hollow cathode discharge He I light source is described in detail and the problems of the sampling of the photoelectrons in such an environment are discussed. For water and most of the alcohols up to six different electronic bands could be resolved. The spectra of 1-butanol and n-nonane show two weakly discernable peaks from which the threshold ionization potential could be determined. A deconvolution of the photoelectron spectra is used to extract ionization potentials of individual molecular bands of molecules near the surface of the liquid and shifts of the order of 1 eV compared to the gas phase are observed. A molecular orientation for water molecules at the surface of liquid water is inferred from a comparison of the relative band strengths with the gas phase. Similar effects are also observed for some of the alcohols. The results are discussed in terms of a simple "Born-solvation" model.

  9. Mineral Specific IR Molar Absorption Coefficients for Routine Water Determination in Olivine, SiO2 polymorphs and Garnet

    NASA Astrophysics Data System (ADS)

    Thomas, S.; Koch-Mueller, M.; Reichart, P.; Rhede, D.; Thomas, R.

    2007-12-01

    Conventionally applied Infrared (IR) calibrations [1, 2] for quantitative water analyses in solids are established on hydrous minerals and glasses with several wt% water. These calibrations are based on a negative correlation between the IR molar absorption coefficient (ɛ) for water and the mean wavenumber of the corresponding OH pattern. The correlation reflects the dependence of the OH band position on the appropriate O- H...O distances and thereby the magnitude of the dipole momentum which is proportional to the band intensity. However, it has been observed that these calibrations can not be adopted to nominally anhydrous minerals (NAMs) [3].To study the potential dependence of ɛ on structure and chemistry in NAMs we synthesized olivine and SiO2 polymorphs with specific isolated hydroxyl point defects, e.g. quartz, coesite and stishovite with B3++H+=Si4+ and/or Al3++H+=Si4+ substitutions. Experiments were performed with water in excess in piston cylinder and multi-anvil presses. Single crystal IR spectra demonstrate that we successfully managed to seperate generally complex OH patterns as e.g. observed in natural quartz and synthetic coesite. We quantified sample water contents of both natural samples and our run products by applying proton-proton-scattering [4], confocal microRaman spectroscopy [5] and Secondary Ion mass spectrometry. Resulting water concentrations were used to calculate new mineral specific ɛs. For olivine with the mean wavenumber of 3517 cm-1 we determined an ɛ value of 41,000±5,000 lmol-1H2Ocm-2. Quantification of olivine with the mean wavenumber of 3550 cm-1 in contrast resulted in an ɛ value of 47,000±1,000 lmol-1H2Ocm-2. Taking into account previous studies [6, 7] there is evidence to suggest a linear wavenumber dependent correlation for olivine, where ɛ increases with decreasing wavenumber. In case of the SiO2 system it turns out that the magnitude of ɛ within one structure type is independent of the liable OH point defect and

  10. Models for a liquid-liquid phase transition

    NASA Astrophysics Data System (ADS)

    Buldyrev, S. V.; Franzese, G.; Giovambattista, N.; Malescio, G.; Sadr-Lahijany, M. R.; Scala, A.; Skibinsky, A.; Stanley, H. E.

    2002-02-01

    We use molecular dynamics simulations to study two- and three-dimensional models with the isotropic double-step potential which in addition to the hard core has a repulsive soft core of larger radius. Our results indicate that the presence of two characteristic repulsive distances (hard core and soft core) is sufficient to explain liquid anomalies and a liquid-liquid phase transition, but these two phenomena may occur independently. Thus liquid-liquid transitions may exist in systems like liquid metals, regardless of the presence of the density anomaly. For 2D, we propose a model with a specific set of hard core and soft core parameters, that qualitatively reproduces the phase diagram and anomalies of liquid water. We identify two solid phases: a square crystal (high density phase), and a triangular crystal (low density phase) and discuss the relation between the anomalies of liquid and the polymorphism of the solid. Similarly to real water, our 2D system may have the second critical point in the metastable liquid phase beyond the freezing line. In 3D, we find several sets of parameters for which two fluid-fluid phase transition lines exist: the first line between gas and liquid and the second line between high-density liquid (HDL) and low-density liquid (LDL). In all cases, the LDL phase shows no density anomaly in 3D. We relate the absence of the density anomaly with the positive slope of the LDL-HDL phase transition line.

  11. Lorentz force in water: evidence that hydronium cyclotron resonance enhances polymorphism.

    PubMed

    D'Emilia, E; Giuliani, L; Lisi, A; Ledda, M; Grimaldi, S; Montagnier, L; Liboff, A R

    2015-01-01

    There is an ongoing question regarding the structure forming capabilities of water at ambient temperatures. To probe for different structures, we studied effects in pure water following magnetic field exposures corresponding to the ion cyclotron resonance of H3O(+). Included were measurements of conductivity and pH. We find that under ion cyclotron resonance (ICR) stimulation, water undergoes a transition to a form that is hydroxonium-like, with the subsequent emission of a transient 48.5 Hz magnetic signal, in the absence of any other measurable field. Our results indicate that hydronium resonance stimulation alters the structure of water, enhancing the concentration of EZ-water. These results are not only consistent with Del Giudice's model of electromagnetically coherent domains, but they can also be interpreted to show that these domains exist in quantized spin states. PMID:25020009

  12. Liquid water absorption and scattering effects in DOAS retrievals over oceans

    NASA Astrophysics Data System (ADS)

    Peters, E.; Wittrock, F.; Richter, A.; Alvarado, L. M. A.; Rozanov, V. V.; Burrows, J. P.

    2014-12-01

    Spectral effects of liquid water are present in absorption (differential optical absorption spectroscopy - DOAS) measurements above the ocean and, if insufficiently removed, may interfere with trace gas absorptions, leading to wrong results. Currently available literature cross sections of liquid water absorption are provided in coarser resolution than DOAS applications require, and vibrational Raman scattering (VRS) is mostly not considered, or is compensated for using simulated pseudo cross sections from radiative transfer modeling. During the ship-based TransBrom campaign across the western Pacific in October 2009, MAX-DOAS (Multi-AXis differential optical absorption spectroscopy) measurements of light penetrating very clear natural waters were performed, achieving average underwater light paths of up to 50 m. From these measurements, the retrieval of a correction spectrum (H2Ocorr) is presented, compensating simultaneously for insufficiencies in the liquid water absorption cross section and broad-banded VRS structures. Small-banded structures caused by VRS were found to be very efficiently compensated for by the intensity offset correction included in the DOAS fit. No interference between the H2Ocorr spectrum and phytoplankton absorption was found. In the MAX-DOAS tropospheric NO2 retrieval, this method was able to compensate entirely for all liquid water effects that decrease the fit quality, and performed better than using a liquid water cross section in combination with a simulated VRS spectrum. The decrease in the residual root mean square (rms) of the DOAS fit depends on the measurement's contamination with liquid water structures, and ranges from ≈ 30% for measurements slightly towards the water surface to several percent in small angles above the horizon. Furthermore, the H2Ocorr spectrum was found to prevent misfits of NO2 slant columns, especially for very low NO2 scenarios, and thus increases the reliability of the fit. In test fits on OMI satellite

  13. Supported liquid membrane-liquid chromatography-mass spectrometry analysis of cyanobacterial toxins in fresh water systems

    NASA Astrophysics Data System (ADS)

    Mbukwa, Elbert A.; Msagati, Titus A. M.; Mamba, Bhekie B.

    Harmful algal blooms (HABs) are increasingly becoming of great concern to water resources worldwide due to indiscriminate waste disposal habits resulting in water pollution and eutrophication. When cyanobacterial cells lyse (burst) they release toxins called microcystins (MCs) that are well known for their hepatotoxicity (causing liver damage) and have been found in eutrophic lakes, rivers, wastewater ponds and other water reservoirs. Prolonged exposure to low concentrated MCs are equally of health importance as they are known to be bioaccumulative and even at such low concentration do exhibit toxic effects to aquatic animals, wildlife and human liver cells. The application of common treatment processes for drinking water sourced from HABs infested reservoirs have the potential to cause algal cell lyses releasing low to higher amounts of MCs in finished water. Trace microcystins in water/tissue can be analyzed and quantified using Liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) following solid-phase extraction (SPE) sample clean-up procedures. However, extracting MCs from algal samples which are rich in chlorophyll pigments and other organic matrices the SPE method suffers a number of drawbacks, including cartridge clogging, long procedural steps and use of larger volumes of extraction solvents. We applied a supported liquid membrane (SLM) based technique as an alternative sample clean-up method for LC-ESI-MS analysis of MCs from both water and algal cells. Four (4) MC variants (MC-RR, -YR, -LR and -WR) from lyophilized cells of Microcystis aeruginosa and water collected from a wastewater pond were identified) and quantified using LC-ESI-MS following a SLM extraction and liquid partitioning step, however, MC-WR was not detected from water extracts. Within 45 min of SLM extraction all studied MCs were extracted and pre-concentrated in approximately 15 μL of an acceptor phase at an optimal pH 2.02 of the donor phase (sample). The highest

  14. Liquid Water Transport in the Reactant Channels of Proton Exchange Membrane Fuel Cells

    NASA Astrophysics Data System (ADS)

    Banerjee, Rupak

    Water management has been identified as a critical issue in the development of PEM fuel cells for automotive applications. Water is present inside the PEM fuel cell in three phases, i.e. liquid phase, vapor phase and mist phase. Liquid water in the reactant channels causes flooding of the cell and blocks the transport of reactants to the reaction sites at the catalyst layer. Understanding the behavior of liquid water in the reactant channels would allow us to devise improved strategies for removing liquid water from the reactant channels. In situ fuel cell tests have been performed to identify and diagnose operating conditions which result in the flooding of the fuel cell. A relationship has been identified between the liquid water present in the reactant channels and the cell performance. A novel diagnostic technique has been established which utilizes the pressure drop multiplier in the reactant channels to predict the flooding of the cell or the drying-out of the membrane. An ex-situ study has been undertaken to quantify the liquid water present in the reactant channels. A new parameter, the Area Coverage Ratio (ACR), has been defined to identify the interfacial area of the reactant channel which is blocked for reactant transport by the presence of liquid water. A parametric study has been conducted to study the effect of changing temperature and the inlet relative humidity on the ACR. The ACR decreases with increase in current density as the gas flow rates increase, removing water more efficiently. With increase in temperature, the ACR decreases rapidly, such that by 60°C, there is no significant ACR to be reported. Inlet relative humidity of the gases does change the saturation of the gases in the channel, but did not show any significant effect on the ACR. Automotive powertrains, which is the target for this work, are continuously faced with transient changes. Water management under transient operating conditions is significantly more challenging and has not

  15. Interactions between liquid-water and gas-diffusion layers in polymer-electrolyte fuel cells

    SciTech Connect

    Das, Prodip K.; Santamaria, Anthony D.; Weber, Adam Z.

    2015-06-11

    Over the past few decades, a significant amount of research on polymer-electrolyte fuel cells (PEFCs) has been conducted to improve performance and durability while reducing the cost of fuel cell systems. However, the cost associated with the platinum (Pt) catalyst remains a barrier to their commercialization and PEFC durability standards have yet to be established. An effective path toward reducing PEFC cost is making the catalyst layers (CLs) thinner thus reducing expensive Pt content. The limit of thin CLs is high gas-transport resistance and the performance of these CLs is sensitive to the operating temperature due to their inherent low water uptake capacity, which results in higher sensitivity to liquid-water flooding and reduced durability. Therefore, reducing PEFC's cost by decreasing Pt content and improving PEFC's performance and durability by managing liquid-water are still challenging and open topics of research. An overlooked aspect nowadays of PEFC water management is the gas-diffusion layer (GDL). While it is known that GDL's properties can impact performance, typically it is not seen as a critical component. In this work, we present data showing the importance of GDLs in terms of water removal and management while also exploring the interactions between liquid-water and GDL surfaces. The critical interface of GDL and gas-flow-channel in the presence of liquid-water was examined through systematic studies of adhesion forces as a function of water-injection rate for various GDLs of varying thickness. GDL properties (breakthrough pressure and adhesion force) were measured experimentally under a host of test conditions. Specifically, the effects of GDL hydrophobic (PTFE) content, thickness, and water-injection rate were examined to identify trends that may be beneficial to the design of liquid-water management strategies and next-generation GDL materials for PEFCs.

  16. Interactions between liquid-water and gas-diffusion layers in polymer-electrolyte fuel cells

    DOE PAGESBeta

    Das, Prodip K.; Santamaria, Anthony D.; Weber, Adam Z.

    2015-06-11

    Over the past few decades, a significant amount of research on polymer-electrolyte fuel cells (PEFCs) has been conducted to improve performance and durability while reducing the cost of fuel cell systems. However, the cost associated with the platinum (Pt) catalyst remains a barrier to their commercialization and PEFC durability standards have yet to be established. An effective path toward reducing PEFC cost is making the catalyst layers (CLs) thinner thus reducing expensive Pt content. The limit of thin CLs is high gas-transport resistance and the performance of these CLs is sensitive to the operating temperature due to their inherent lowmore » water uptake capacity, which results in higher sensitivity to liquid-water flooding and reduced durability. Therefore, reducing PEFC's cost by decreasing Pt content and improving PEFC's performance and durability by managing liquid-water are still challenging and open topics of research. An overlooked aspect nowadays of PEFC water management is the gas-diffusion layer (GDL). While it is known that GDL's properties can impact performance, typically it is not seen as a critical component. In this work, we present data showing the importance of GDLs in terms of water removal and management while also exploring the interactions between liquid-water and GDL surfaces. The critical interface of GDL and gas-flow-channel in the presence of liquid-water was examined through systematic studies of adhesion forces as a function of water-injection rate for various GDLs of varying thickness. GDL properties (breakthrough pressure and adhesion force) were measured experimentally under a host of test conditions. Specifically, the effects of GDL hydrophobic (PTFE) content, thickness, and water-injection rate were examined to identify trends that may be beneficial to the design of liquid-water management strategies and next-generation GDL materials for PEFCs.« less

  17. Sequential dispersive liquid-liquid microextraction for the determination of aryloxyphenoxy-propionate herbicides in water.

    PubMed

    Li, Songqing; Gao, Peng; Zhang, Jiaheng; Li, Yubo; Peng, Bing; Gao, Haixiang; Zhou, Wenfeng

    2012-12-01

    A novel dispersive liquid-liquid microextraction (DLLME) method followed by HPLC analysis, termed sequential DLLME, was developed for the preconcentration and determination of aryloxyphenoxy-propionate herbicides (i.e. haloxyfop-R-methyl, cyhalofop-butyl, fenoxaprop-P-ethyl, and fluazifop-P-butyl) in aqueous samples. The method is based on the combination of ultrasound-assisted DLLME with in situ ionic liquid (IL) DLLME into one extraction procedure and achieved better performance than widely used DLLME procedures. Chlorobenzene was used as the extraction solvent during the first extraction. Hydrophilic IL 1-octyl-3-methylimidazolium chloride was used as a dispersive solvent during the first extraction and as an extraction solvent during the second extraction after an in situ chloride exchange by bis[(trifluoromethane)sulfonyl]imide. Several experimental parameters affecting the extraction efficiency were studied and optimized with the design of experiments using MINITAB® 16 software. Under the optimized conditions, the extractions resulted in analyte recoveries of 78-91%. The correlation coefficients of the calibration curves ranged from 0.9994 to 0.9997 at concentrations of 10-300, 15-300, and 20-300 μg L(-1). The relative SDs (n = 5) ranged from 2.9 to 5.4%. The LODs for the four herbicides were between 1.50 and 6.12 μg L(-1). PMID:23109344

  18. FT-IR and dielectric study of water/AOT liquid crystals

    NASA Astrophysics Data System (ADS)

    Calandra, P.; Caponetti, E.; Chillura Martino, D.; D'Angelo, P.; Minore, A.; Turco Liveri, V.

    2000-04-01

    In order to explore the influence of microwave radiation on highly viscous microheterogeneous systems, the evolution of structural and dynamical properties of the water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT) liquid crystals as a function of the molar ratio R ( R=[water]/[AOT]) has been investigated by FT-IR spectroscopy and time domain reflectometry. The study emphasises how the progressive hydration of the surfactant head groups is mainly responsible for the structural and dynamical evolution of water/AOT liquid crystals. In particular, it has been found that the state of water at lower R values is strongly perturbed, bulk-like water appears only at R>23 and the water/AOT interface polarisation is controlled by the fast translational dynamics of sodium counterions and the slow orientational dynamics of the AOT ionic head groups.

  19. Water transport in water-in-oil-in-water liquid emulsion membrane system for the separation of lactic acid

    SciTech Connect

    Mok, Y.S.; Lee, W.K. )

    1994-03-01

    Liquid emulsion membranes (LEMs) were applied to the separation of lactic acid from an aqueous feed phase, and water transport (swelling) was investigated during the separation. Considering that as lactic acid was extracted into the internal stripping phase, osmotic pressure difference across the membrane was varied, the water transfer coefficient was evaluated. The water transfer coefficient was larger at higher carrier concentration and initial lactic acid concentration, which means that emulsion swelling can also be mediated by solute/carrier complexes although it is, in general, osmotically induced. The appropriate LEM formulation was given for separation and concentration of lactic acid. If both separation and concentration are desired, evidently emulsion swelling should be considered in conjunction with the transport rate of lactic acid. It was observed that the separated solute concentration in the internal phase was lowered due to swelling during the operation. Nevertheless, lactic acid could be concentrated in the internal phase more than 6 times in specific conditions, indicating that as the volume ratio of external phase to internal phase is increased, a still higher concentration in the internal phase can be obtained. 22 refs., 10 figs., 4 tabs.

  20. Conformational Heat Capacity of Liquid Biodegradable Polymers in the Absence and Presence Water

    NASA Astrophysics Data System (ADS)

    Pyda, Marek; Nowak-Pyda, Elzbieta

    2007-03-01

    The conformational heat capacity of biodegradable polymers such as amorphous poly(lactic acid) PLA and starch with and without water have been evaluated from a fit of experimental data to a one-dimensional Ising-like model for two discrete states, characterized by parameters linked to stiffness, cooperativity, and degeneracy. For the starch-water system the additional changes in the conformational heat capacity arise from the interaction of the carbohydrate chains with water. The liquid heat capacities at constant pressure Cp, of amorphous PLA and partially liquid state of starch, starch-water have been computed as the sum of vibrational, external, and conformational contributions. The vibrational contribution was calculated as the heat capacity arising from group and skeletal vibrations. The external contribution was estimated from experimental data of the thermal expansivity and compressibility in the liquid state. The experimental liquid Cp agrees with these calculations to better than ±3%. The calculated liquid Cp with the solid Cp was employed in the quantitative thermal analysis of the experimental Cp of biodegradable polymer PLA, starch, and starch-water. Supported by European Union, grant (MIRG-CT-2006-036558), Cargill Dow LLC

  1. Bulk volumetric liquid water content in a seasonal snowpack: modeling its dynamics in different climatic conditions

    NASA Astrophysics Data System (ADS)

    Avanzi, Francesco; Yamaguchi, Satoru; Hirashima, Hiroyuki; De Michele, Carlo

    2015-12-01

    We focus on the dynamics of volumetric liquid water content in seasonal snow covers. This is a key variable describing the fate of snowpacks during the melting season. However, its measurement and/or prediction by means of models at high spatial and temporal resolutions is still difficult due to both practical and theoretical reasons. To overcome these limitations in operational applications, we test the capability of a one-dimensional model to predict the dynamics of bulk volumetric liquid water content during a snow season. Multi-year data collected in three experimental sites in Japan are used as an evaluation. These sites are subjected to different climatic conditions. The model requires the calibration of one or two parameters, according to the degree of detail used. Either a simple temperature-index or a coupled melt-freeze temperature-index approach are considered to predict melting and/or melt-freeze dynamics of liquid water. Results show that, if melt-freeze dynamics are modeled, median absolute differences between data and predictions are consistently lower than 1 vol% at the sites where data of liquid water content are available. In addition, we find also that the model predicts correctly a dry condition in 80% of the observed cases at a site where calibration data are scarce. At the same site, observed isothermal conditions of the snow cover at 0 °C correspond to predictions of bulk volumetric liquid water content that are greater than 0.

  2. Optical and topographic changes in water-responsive patterned cholesteric liquid crystalline polymer coatings

    NASA Astrophysics Data System (ADS)

    Stumpel, Jelle E.; Broer, Dirk J.; Bastiaansen, Cees W. M.; Schenning, Albert P. H. J.

    2014-05-01

    In this work, we present patterned water-responsive coatings, which alter both their topological and optical properties. The polymer coatings are based on a hydrogen-bonded cholesteric liquid crystalline polymer network. A two-step photopolymerization procedure leads to a patterned coating with repeating liquid crystalline and isotropic areas. The cholesteric liquid crystalline areas reflect green light, whilst the isotropic areas are transparent for visible light. Treatment with alkaline solution results in a hygroscopic polymer salt coating. When placed in demineralized water, the polymer films swells, leading to an enhancement of the surface topography structure in which the liquid crystalline areas swell more. Moreover, the pitch of the helical organization in the cholesteric areas increases due to this swelling leading to a color change from green to red.

  3. Water in Ionic Liquids: Correlation between Anion Hydrophilicity and Near-Infrared Fingerprints.

    PubMed

    TomŠík, Elena; Gospodinova, Natalia

    2016-06-01

    We show that fingerprints of the different states of water association can be clearly distinguished in the range of the first overtone of water's symmetric O-H stretching in the spectra of water-saturated [EMIm](+) -based ionic liquids with anions of substantially different hydrophilicity, such as hydrophobic [(CF3 SO2 )2 N](-) , moderately hydrophilic [CF3 SO3 ](-) , and highly hydrophilic [HSO4 ](-) . PMID:27001562

  4. Air-Liquid Interfaces: II. Water Structure and Salts

    NASA Astrophysics Data System (ADS)

    Allen, Heather; Gopalakrishnan, Sandhya; Ma, Gang; Liu, Dingfang; Levering, Lori

    2004-03-01

    Aqueous salt solutions were investigated using scanning sum frequency generation (SFG), a highly surface-selective spectroscopy, and ATR-IR and Raman spectroscopies. Water surface structure was investigated for NaF, NaCl, NaBr and NaI aqueous solutions and surface data indicate a significantly disturbed hydrogen bonding environment from that of neat water. The spectra strongly suggest the presence of bromide and iodide anions in the interfacial region in addition to an increase in interfacial depth; yet the surfaces of the sodium fluoride and chloride salt solutions do not show evidence of surface water perturbation. Ammonium chloride and sulfate, and sodium sulfate aqueous solutions were also investigated. Surface water structure varied considerably between the three salt solutions. Electric double layer effects are indicated.

  5. Regional water implications of reducing oil imports with liquid transportation fuel alternatives in the United States.

    PubMed

    Jordaan, Sarah M; Diaz Anadon, Laura; Mielke, Erik; Schrag, Daniel P

    2013-01-01

    The Renewable Fuel Standard (RFS) is among the cornerstone policies created to increase U.S. energy independence by using biofuels. Although greenhouse gas emissions have played a role in shaping the RFS, water implications are less understood. We demonstrate a spatial, life cycle approach to estimate water consumption of transportation fuel scenarios, including a comparison to current water withdrawals and drought incidence by state. The water consumption and land footprint of six scenarios are compared to the RFS, including shale oil, coal-to-liquids, shale gas-to-liquids, corn ethanol, and cellulosic ethanol from switchgrass. The corn scenario is the most water and land intense option and is weighted toward drought-prone states. Fossil options and cellulosic ethanol require significantly less water and are weighted toward less drought-prone states. Coal-to-liquids is an exception, where water consumption is partially weighted toward drought-prone states. Results suggest that there may be considerable water and land impacts associated with meeting energy security goals through using only biofuels. Ultimately, water and land requirements may constrain energy security goals without careful planning, indicating that there is a need to better balance trade-offs. Our approach provides policymakers with a method to integrate federal policies with regional planning over various temporal and spatial scales. PMID:24047132

  6. Liquid Water: Obtaining the right answer for the right reasons

    SciTech Connect

    Apra, Edoardo; Rendell, Alistair P.; Harrison, Robert J.; Tipparaju, Vinod; De Jong, Wibe A.; Xantheas, Sotiris S.

    2009-11-14

    Water is ubiquitous on our planet and plays an essential role in many chemical and biological processes. Accurate models for water are crucial in understanding, controlling and predicting the physical and chemical properties of complex aqueous systems. Over the last few years we have been developing a molecular-level based approach for a macroscopic model for water that is based on the explicit description of the underlying intermolecular interactions between molecules in water clusters. In the absence of detailed experimental data for small water clusters, highly-accurate theoretical results are required to validate and parameterize model potentials. As an example of the benchmarks needed for the development of accurate models for the interaction between water molecules, for the most stable structure of (H2O)20 we ran a coupled-cluster calculation on the ORNL’s Jaguar petaflop computer that used over 100 TB of memory for a sustained performance of 487 TFLOP/s (double precision) on 96,000 processors, lasting for 2 hours. By this summer we will have studied multiple structures of both (H2O)20 and (H2O)30 and completed basis set and other convergence studies and anticipate the sustained performance rising close to 1 PFLOP/s.

  7. Liquid Water: Obtaining the right answer for the right reasons

    SciTech Connect

    Apra, Edoardo; Harrison, Robert J; de Jong, Wibe A; Rendell, Alistair P; Tipparaju, Vinod; Xantheas, Sotiris

    2009-01-01

    Water is ubiquitous on our planet and plays an essential role in many chemical and biological processes. Accurate models for water are crucial in understanding, controlling and predicting the physical and chemical properties of complex aqueous systems. Over the last few years we have been developing a molecular-level based approach for a macroscopic model for water that is based on the explicit description of the underlying intermolecular interactions between molecules in water clusters. In the absence of detailed experimental data for small water clusters, highly-accurate theoretical results are required to validate and parameterize model potentials. As an example of the benchmarks needed for the development of accurate models for the interaction between water molecules, for the most stable structure of (H$_2$O)$_{20}$ we ran a coupled-cluster calculation on the ORNL's Jaguar petaflop computer that used over 100 TB of memory for a sustained performance of 487 TFLOP/s (double precision) on 96,000 processors, lasting for 2 hours. By this summer we will have studied multiple structures of both (H$_2$O)$_{20}$ and (H$_2$O)$_{30}$ and completed basis set and other convergence studies and anticipate the sustained performance rising close to 1 PFLOP/s.

  8. Sodium-water reaction acoustic noise for liquid phase injections. [LMFBR

    SciTech Connect

    Callis, K.R.; Greene, D.A.; Malovrh, J.W.

    1981-02-01

    Data on liquid and steam injections into sodium were recorded during a series of wastage experiments. These data are analyzed for acoustic power and spectral characteristics, expanding the data base up to 10 gm/sec injection rates from the earlier 0.5 gms/sec. No significant difference in acoustic power was measured between low temperature steam and liquid injections for the same mass flowrates. The bandwidth for steam injections is broader than for liquid injections. Reaction product deposition during water injections appears to cause a decrease in signal strength with test duration.

  9. 30 CFR 250.217 - What solid and liquid wastes and discharges information and cooling water intake information must...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... information and cooling water intake information must accompany the EP? 250.217 Section 250.217 Mineral... What solid and liquid wastes and discharges information and cooling water intake information must accompany the EP? The following solid and liquid wastes and discharges information and cooling water...

  10. 30 CFR 550.248 - What solid and liquid wastes and discharges information and cooling water intake information must...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... information and cooling water intake information must accompany the DPP or DOCD? 550.248 Section 550.248... liquid wastes and discharges information and cooling water intake information must accompany the DPP or DOCD? The following solid and liquid wastes and discharges information and cooling water...

  11. 30 CFR 550.217 - What solid and liquid wastes and discharges information and cooling water intake information must...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... information and cooling water intake information must accompany the EP? 550.217 Section 550.217 Mineral... What solid and liquid wastes and discharges information and cooling water intake information must accompany the EP? The following solid and liquid wastes and discharges information and cooling water...

  12. Impact of water vapour and carbon dioxide on surface composition of C{sub 3}A polymorphs studied by X-ray photoelectron spectroscopy

    SciTech Connect

    Dubina, E.; Plank, J.; Black, L.

    2015-07-15

    The surface specific analytical method, X-ray photoelectron spectroscopy (XPS), has been used to study the effects of water vapour and CO{sub 2} on the cubic and orthorhombic polymorphs of C{sub 3}A. Significant differences between the two polymorphs were observed in the XPS spectra. Upon exposure to water vapour, both polymorphs produced C{sub 4}AH{sub 13} on their surfaces. Additionally, the sodium-doped o-C{sub 3}A developed NaOH and traces of C{sub 3}AH{sub 6} on its surface. Subsequent carbonation yielded mono carboaluminate on both polymorphs. Large amounts of Na{sub 2}CO{sub 3} also formed on the surface of o-C{sub 3}A as a result of carbonation of NaOH. Furthermore, the extent of carbonation was much more pronounced for o-C{sub 3}A{sub o} than for c-C{sub 3}A.

  13. Measurement and Estimation of Organic-Liquid/Water Interfacial Areas for Several Natural Porous Media

    SciTech Connect

    Brusseau, M.L.; Narter, M.; Schnaar, G.; Marble, J.

    2009-06-01

    The objective of this study was to quantitatively characterize the impact of porous-medium texture on interfacial area between immiscible organic liquid and water residing within natural porous media. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of solid and liquid phases in packed columns. The image data were processed to generate quantitative measurements of organic-liquid/water interfacial area and of organic-liquid blob sizes. Ten porous media, comprising a range of median grain sizes, grain-size distributions, and geochemical properties, were used to evaluate the impact of porous-medium texture on interfacial area. The results show that fluid-normalized specific interfacial area (A{sub f}) and maximum specific interfacial area (A{sub m}) correlate very well to inverse median grain diameter. These functionalities were shown to result from a linear relationship between effective organic-liquid blob diameter and median grain diameter. These results provide the basis for a simple method for estimating specific organic-liquid/water interfacial area as a function of fluid saturation for a given porous medium. The availability of a method for which the only parameter needed is the simple-to-measure median grain diameter should be of great utility for a variety of applications.

  14. Revisiting the total ion yield x-ray absorption spectra of liquid water microjets

    SciTech Connect

    Saykally, Richard J; Cappa, Chris D.; Smith, Jared D.; Wilson, Kevin R.; Saykally, Richard J.

    2008-02-16

    Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al. (2002 J. Phys.: Condens. Matter 14 L221 and 2001 J. Phys. Chem. B 105 3346) have been revisited in light of new experimental and theoretical efforts by our group. Previously, the TIY spectrum was interpreted as a distinct measure of the electronic structure of the liquid water surface. However, our new results indicate that the previously obtained spectrum may have suffered from as yet unidentified experimental artifacts. Although computational results indicate that the liquid water surface should exhibit a TIY-XAS that is fundamentally distinguishable from the bulk liquid XAS, the new experimental results suggest that the observable TIY-XAS is actually nearly identical in appearance to the total electron yield (TEY-)XAS, which is a bulk probe. This surprising similarity between the observed TIY-XAS and TEY-XAS likely results from large contributions from x-ray induced electron stimulated desorption of ions, and does not necessarily indicate that the electronic structure of the bulk liquid and liquid surface are identical.

  15. Thermodynamics of open networks: Ordering and entropy in NaAlSiO4 glass, liquid, and polymorphs

    USGS Publications Warehouse

    Richet, P.; Robie, R.A.; Rogez, J.; Hemingway, B.S.; Courtial, P.; Tequi, C.

    1990-01-01

    The thermodynamic properties of carnegieite and NaAlSiO4 glass and liquid have been investigated through Cp determinations from 10 to 1800 K and solution-calorimetry measurements. The relative entropies S298-S0 of carnegieite and NaAlSiO4 glass are 118.7 and 124.8 J/mol K, respectively. The low-high carnegieite transition has been observed at 966 K with an enthalpy of transition of 8.1??0.3 kJ/mol, and the enthalpy of fusion of carnegieite at the congruent melting point of 1799 K is 21.7??3 kJ/mol. These results are consistent with the reported temperature of the nepheline-carnegieite transition and available thermodynamic data for nepheline. The entropy of quenched NaAlSiO4 glass at 0 K is 9.7??2 J/mol K and indicates considerable ordering among AlO4 and SiO4 tetrahedra. In the liquid state, progressive, temperature-induced Si, Al disordering could account for the high configurational heat capacity. Finally, the differences between the entropies and heat capacities of nepheline and carnegieite do not seem to conform to current polyhedral modeling of these properties ?? 1990 Springer-Verlag.

  16. Rheological properties of ammonia-water liquids and crystal-liquid slurries - Planetological applications

    NASA Technical Reports Server (NTRS)

    Kargel, J. S.; Croft, S. K.; Lunine, J. I.; Lewis, J. S.

    1991-01-01

    The laboratory-measured viscosities of liquid mixtures representative of the variety of cryovolcanic substances of the icy satellites are presently noted to be much greater than could be expected on the assumption that end-member molecules are noninteractive; this observation is supported by others concerning molar volumes and vapor pressure relations, which indicate the presence of strong molecular-interaction forces that fundamentally affect the mixtures' physical properties. Since the rheological effects of partial crystallization parallel the characteristics of silicate lavas, icy satellite cryovolcanic morphologies are similarly interpretable with allowances for differences in surface gravities and lava densities.

  17. The dielectric behaviour of snow: A study versus liquid water content

    NASA Technical Reports Server (NTRS)

    Ambach, W.; Denoth, A.

    1980-01-01

    Snow is treated as a heterogeneous dielectric material consisting of ice, air, and water. The greater difference in the high frequency relative permittivity of dry snow and water allows to determine the liquid water content by measurements of the relative permittivity of snow. A plate condenser with a volume of about 1000 cv cm was used to measure the average liquid water content in a snow volume. Calibration was carried out using a freezing calorimeter. In order to measure the liquid water content in thin snow layers, a comb-shaped condenser was developed, which is the two dimensional analogon of the plate condenser. With this moisture meter the liquid water content was measured in layers of a few millimeters in thickness, whereby the effective depth of measurement is given by the penetration depth of electric field lines which is controlled by the spacing of the strip lines. Results of field measurements with both moisture meters, the plate condenser and the comb-shaped condenser, are given.

  18. Raman Thermometry Measurements of Free Evaporation from LiquidWater Droplets

    SciTech Connect

    Smith, Jared D.; Cappa, Christopher D.; Drisdell, Walter S.; Cohen, Ron ald C.; Saykally, Richard J.

    2006-05-22

    Recent theoretical and experimental studies of evaporation have suggested that on average, molecules in the higher-energy tail of the Boltzmann distribution are more readily transferred into the vapor during evaporation. To test these conclusions, the evaporative cooling rates of a droplet train of liquid water injected into vacuum have been studied via Raman thermometry. The resulting cooling rates are fit to an evaporative cooling model based on Knudsen's maximum rate of evaporation, in which we explicitly account for surface cooling. We have determined that the value of the evaporation coefficient ({gamma}{sub e}) of liquid water is 0.62 {+-} 0.09, confirming that a rate-limiting barrier impedes the evaporation rate. Such insight will facilitate the formulation of a microscopic mechanism for the evaporation of liquid water.

  19. Multimycotoxin analysis in water and fish plasma by liquid chromatography-tandem mass spectrometry.

    PubMed

    Tolosa, J; Font, G; Mañes, J; Ferrer, E

    2016-02-01

    High performance liquid chromatography-mass spectrometry was used for the determination of 15 mycotoxins in water and fish plasma samples, including aflatoxins, fumonisins, ochratoxin A, sterigmatocistin, fusarenon-X and emerging Fusarium mycotoxins. In this work, dispersive liquid-liquid microextraction (DLLME) was assessed as a sample treatment for the simultaneous extraction of mycotoxins. Results showed differences in recovery assays when different extraction solvents were employed. Ethyl acetate showed better recoveries for the major part of mycotoxins analyzed, except for aflatoxins B2, G1 and G2, which showed better recoveries when employing chloroform as extractant solvent. Fumonisins and beauvericin exhibited low recoveries in both water and plasma. This method was validated according to guidelines established by European Commission and has shown to be suitable to be applied in dietary and/or toxicokinetic studies in fish where is necessary to check mycotoxin contents in rearing water and fish plasma. PMID:26694790

  20. Structure and Dynamics of Low-Density and High-Density Liquid Water at High Pressure.

    PubMed

    Fanetti, Samuele; Lapini, Andrea; Pagliai, Marco; Citroni, Margherita; Di Donato, Mariangela; Scandolo, Sandro; Righini, Roberto; Bini, Roberto

    2014-01-01

    Liquid water has a primary role in ruling life on Earth in a wide temperature and pressure range as well as a plethora of chemical, physical, geological, and environmental processes. Nevertheless, a full understanding of its dynamical and structural properties is still lacking. Water molecules are associated through hydrogen bonds, with the resulting extended network characterized by a local tetrahedral arrangement. Two different local structures of the liquid, called low-density (LDW) and high-density (HDW) water, have been identified to potentially affect many different chemical, biological, and physical processes. By combining diamond anvil cell technology, ultrafast pump-probe infrared spectroscopy, and classical molecular dynamics simulations, we show that the liquid structure and orientational dynamics are intimately connected, identifying the P-T range of the LDW and HDW regimes. The latter are defined in terms of the speeding up of the orientational dynamics, caused by the increasing probability of breaking and reforming the hydrogen bonds. PMID:26276206

  1. Accurate Optical Detection of Amphiphiles at Liquid-Crystal-Water Interfaces

    NASA Astrophysics Data System (ADS)

    Popov, Piotr; Mann, Elizabeth K.; Jákli, Antal

    2014-04-01

    Liquid-crystal-based biosensors utilize the high sensitivity of liquid-crystal alignment to the presence of amphiphiles adsorbed to one of the liquid-crystal surfaces from water. They offer inexpensive, easy optical detection of biologically relevant molecules such as lipids, proteins, and cells. Present techniques use linear polarizers to analyze the alignment of the liquid crystal. The resulting images contain information not only about the liquid-crystal tilt with respect to the surface normal, the quantity which is controlled by surface adsorption, but also on the uncontrolled in-plane liquid-crystal alignment, thus making the detection largely qualitative. Here we show that detecting the liquid-crystal alignment between circular polarizers, which are only sensitive to the liquid-crystal tilt with respect to the interface normal, makes possible quantitative detection by measuring the transmitted light intensity with a spectrophotometer. Following a new procedure, not only the concentration dependence of the optical path difference but also the film thickness and the effective birefringence can be determined accurately. We also introduce a new "dynamic" mode of sensing, where (instead of the conventional "steady" mode, which detects the concentration dependence of the steady-state texture) we increase the concentration at a constant rate.

  2. Short-range precipitation forecasts using assimilation of simulated satellite water vapor profiles and column cloud liquid water amounts

    NASA Technical Reports Server (NTRS)

    Wu, Xiaohua; Diak, George R.; Hayden, Cristopher M.; Young, John A.

    1995-01-01

    These observing system simulation experiments investigate the assimilation of satellite-observed water vapor and cloud liquid water data in the initialization of a limited-area primitive equations model with the goal of improving short-range precipitation forecasts. The assimilation procedure presented includes two aspects: specification of an initial cloud liquid water vertical distribution and diabatic initialization. The satellite data is simulated for the next generation of polar-orbiting satellite instruments, the Advanced Microwave Sounding Unit (AMSU) and the High-Resolution Infrared Sounder (HIRS), which are scheduled to be launched on the NOAA-K satellite in the mid-1990s. Based on cloud-top height and total column cloud liquid water amounts simulated for satellite data a diagnostic method is used to specify an initial cloud water vertical distribution and to modify the initial moisture distribution in cloudy areas. Using a diabatic initialization procedure, the associated latent heating profiles are directly assimilated into the numerical model. The initial heating is estimated by time averaging the latent heat release from convective and large-scale condensation during the early forecast stage after insertion of satellite-observed temperature, water vapor, and cloud water formation. The assimilation of satellite-observed moisture and cloud water, together withy three-mode diabatic initialization, significantly alleviates the model precipitation spinup problem, especially in the first 3 h of the forecast. Experimental forecasts indicate that the impact of satellite-observed temperature and water vapor profiles and cloud water alone in the initialization procedure shortens the spinup time for precipitation rates by 1-2 h and for regeneration of the areal coverage by 3 h. The diabatic initialization further reduces the precipitation spinup time (compared to adiabatic initialization) by 1 h.

  3. Dual Spectrum Neutron Radiography: Identification of Phase Transitions between Frozen and Liquid Water

    NASA Astrophysics Data System (ADS)

    Biesdorf, J.; Oberholzer, P.; Bernauer, F.; Kaestner, A.; Vontobel, P.; Lehmann, E. H.; Schmidt, T. J.; Boillat, P.

    2014-06-01

    In this Letter, a new approach to distinguish liquid water and ice based on dual spectrum neutron radiography is presented. The distinction is based on arising differences between the cross section of water and ice in the cold energy range. As a significant portion of the energy spectrum of the ICON beam line at Paul Scherrer Institut is in the thermal energy range, no differences can be observed with the entire beam. Introducing a polycrystalline neutron filter (beryllium) inside the beam, neutrons above its cutoff energy are filtered out and the cold energy region is emphasized. Finally, a contrast of about 1.6% is obtained with our imaging setup between liquid water and ice. Based on this measurement concept, the temporal evolution of the aggregate state of water can be investigated without any prior knowledge of its thickness. Using this technique, we could unambiguously prove the production of supercooled water inside fuel cells with a direct measurement method.

  4. Formation of Martian Gullies by the Action of Liquid Water Flowing Under Current Martian Environmental Conditions

    NASA Technical Reports Server (NTRS)

    Heldmann, J. L.; Toon, O. B.; Pollard, W. H.; Mellon, M. T.; Pitlick, J.; McKay, C. P.; Andersen, D. T.

    2005-01-01

    Images from the Mars Orbiter Camera (MOC) on the Mars Global Surveyor (MGS) spacecraft show geologically young small-scale features resembling terrestrial water-carved gullies. An improved understanding of these features has the potential to reveal important information about the hydrological system on Mars, which is of general interest to the planetary science community as well as the field of astrobiology and the search for life on Mars. The young geologic age of these gullies is often thought to be a paradox because liquid water is unstable at the Martian surface. Current temperatures and pressures are generally below the triple point of water (273 K, 6.1 mbar) so that liquid water will spontaneously boil and/or freeze. We therefore examine the flow of water on Mars to determine what conditions are consistent with the observed features of the gullies.

  5. Dual spectrum neutron radiography: identification of phase transitions between frozen and liquid water.

    PubMed

    Biesdorf, J; Oberholzer, P; Bernauer, F; Kaestner, A; Vontobel, P; Lehmann, E H; Schmidt, T J; Boillat, P

    2014-06-20

    In this Letter, a new approach to distinguish liquid water and ice based on dual spectrum neutron radiography is presented. The distinction is based on arising differences between the cross section of water and ice in the cold energy range. As a significant portion of the energy spectrum of the ICON beam line at Paul Scherrer Institut is in the thermal energy range, no differences can be observed with the entire beam. Introducing a polycrystalline neutron filter (beryllium) inside the beam, neutrons above its cutoff energy are filtered out and the cold energy region is emphasized. Finally, a contrast of about 1.6% is obtained with our imaging setup between liquid water and ice. Based on this measurement concept, the temporal evolution of the aggregate state of water can be investigated without any prior knowledge of its thickness. Using this technique, we could unambiguously prove the production of supercooled water inside fuel cells with a direct measurement method. PMID:24996112

  6. An attempt to monitor liquid water content in seasonal snow using capacitance probes

    NASA Astrophysics Data System (ADS)

    Avanzi, Francesco; Caruso, Marco; Jommi, Cristina; De Michele, Carlo; Ghezzi, Antonio

    2015-04-01

    Liquid water dynamics in snow are a key factor in wet snow avalanche triggering, in ruling snowmelt runoff timing and amounts, and in remote sensing interpretation. It follows that a continuous-time monitoring of this variable would be very desirable. Nevertheless, such an operation is nowadays hampered by the difficulty in obtaining direct, precise and continuous-time measurements of this quantity without perturbing the snowpack itself. As a result, only a few localized examples exist of continuous-time measurements of this variable. In this framework, we tried to get undisturbed measurements of liquid water content using capacitance probes. These instruments were originally designed to obtain liquid water content data in soils. After being installed on a support and driven in the snow, they include part of the medium under investigation in a LC circuit. The resonant frequency of the circuit depends on liquid water content, hence its measurement. To test these sensors, we designed two different field surveys (in April 2013 and April 2014) at a medium elevation site (around 1980 m a.s.l.). In both the cases, a profile of sensors was inserted in the snowpack, and undisturbed measurements of liquid water content were obtained using time-domain-reflectometry based devices. To assist in the interpretation of the readings from these sensors, some laboratory tests were run, and a FEM model of a sensor was implemented. Results show that sensors are sensitive to increasing liquid water content in snow. Nonetheless, long-term tests in snow cause the systematic development of an air gap between the instrument and the surrounding snow, that hampers the interpretation. Perspectives on future investigation are discussed to bring the proposed procedure towards long-term applications in snowpacks.

  7. Plasma Discharges in Gas Bubbles in Liquid Water: Breakdown Mechanisms and Resultant Chemistry

    NASA Astrophysics Data System (ADS)

    Gucker, Sarah M. N.

    The use of atmospheric pressure plasmas in gases and liquids for purification of liquids has been investigated by numerous researchers, and is highly attractive due to their strong potential as a disinfectant and sterilizer. However, the fundamental understanding of plasma production in liquid water is still limited. Despite the decades of study dedicated to electrical discharges in liquids, many physical aspects of liquids, such as the high inhomogeneity of liquids, complicate analyses. For example, the complex nonlinearities of the fluid have intricate effects on the electric field of the propagating streamer. Additionally, the liquid material itself can vaporize, leading to discontinuous liquid-vapor boundaries. Both can and do often lead to notable hydrodynamic effects. The chemistry of these high voltage discharges on liquid media can have circular effects, with the produced species having influence on future discharges. Two notable examples include an increase in liquid conductivity via charged species production, which affects the discharge. A second, more complicated scenario seen in some liquids (such as water) is the doubling or tripling of molecular density for a few molecule layers around a high voltage electrode. These complexities require technological advancements in optical diagnostics that have only recently come into being. This dissertation investigates several aspects of electrical discharges in gas bubbles in liquids. Two primary experimental configurations are investigated: the first allows for single bubble analysis through the use of an acoustic trap. Electrodes may be brought in around the bubble to allow for plasma formation without physically touching the bubble. The second experiment investigates the resulting liquid phase chemistry that is driven by the discharge. This is done through a dielectric barrier discharge with a central high voltage surrounded by a quartz discharge tube with a coil ground electrode on the outside. The plasma

  8. A new device for magnetic stirring-assisted dispersive liquid-liquid microextraction of UV filters in environmental water samples.

    PubMed

    Zhang, Ping-Ping; Shi, Zhi-Guo; Yu, Qiong-Wei; Feng, Yu-Qi

    2011-02-15

    A new method based on dispersive liquid-liquid microextraction (DLLME) in combination with high-performance liquid chromatography (HPLC) has been developed for the analysis of UV filters. A specially designed flask, which has two narrow open necks with one of them having a capillary tip, was employed to facilitate the DLLME process. By adopting such a device, the extraction and subsequent phase separation were conveniently achieved. A binary solvent system of water sample and low-density extraction solvent (1-octanol) was used for the DLLME and no disperser solvent was involved. The extraction was accelerated by magnetic agitation of the two phases. After extraction, phase separation of the extraction solvent from the aqueous sample was easily achieved by leaving the extraction system statically for a while. No centrifugation step involving in classical DLLME was necessary. The analyte-enriched phase, floating above the sample solution, was elevated and concentrated into the narrow open tip of the flask by adding pure water into it via the other port, which was withdrawn with a microsyringe for the subsequent HPLC analysis. Under the optimized conditions, the limits of detection for the analytes were in range of 0.2-0.8ngmL(-1) .The linearity ranges were 8-20,000 ng mL(-1) for HB, 7-20,000 ng mL(-1) for DB, 8-10,000 ng mL(-1) for BP and 5-20,000 ng mL(-1) for HMB, respectively. Enrichment factors ranging from 59 to 107 folders were obtained for the analytes. The relative standard deviations (n=3) at a spiked level of 80 ng mL(-1) were between 1.4 and 4.8%. The proposed magnetic stirring-assisted DLLME method was successfully applied to the analysis of lake water samples. PMID:21238773

  9. Heating-induced glass-glass and glass-liquid transformations in computer simulations of water

    SciTech Connect

    Chiu, Janet; Giovambattista, Nicolas; Starr, Francis W.

    2014-03-21

    Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T “phase diagram” for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related

  10. Heating-induced glass-glass and glass-liquid transformations in computer simulations of water.

    PubMed

    Chiu, Janet; Starr, Francis W; Giovambattista, Nicolas

    2014-03-21

    Water exists in at least two families of glassy states, broadly categorized as the low-density (LDA) and high-density amorphous ice (HDA). Remarkably, LDA and HDA can be reversibly interconverted via appropriate thermodynamic paths, such as isothermal compression and isobaric heating, exhibiting first-order-like phase transitions. We perform out-of-equilibrium molecular dynamics simulations of glassy water using the ST2 model to study the evolution of LDA and HDA upon isobaric heating. Depending on pressure, glass-to-glass, glass-to-crystal, glass-to-vapor, as well as glass-to-liquid transformations are found. Specifically, heating LDA results in the following transformations, with increasing heating pressures: (i) LDA-to-vapor (sublimation), (ii) LDA-to-liquid (glass transition), (iii) LDA-to-HDA-to-liquid, (iv) LDA-to-HDA-to-liquid-to-crystal, and (v) LDA-to-HDA-to-crystal. Similarly, heating HDA results in the following transformations, with decreasing heating pressures: (a) HDA-to-crystal, (b) HDA-to-liquid-to-crystal, (c) HDA-to-liquid (glass transition), (d) HDA-to-LDA-to-liquid, and (e) HDA-to-LDA-to-vapor. A more complex sequence may be possible using lower heating rates. For each of these transformations, we determine the corresponding transformation temperature as function of pressure, and provide a P-T "phase diagram" for glassy water based on isobaric heating. Our results for isobaric heating dovetail with the LDA-HDA transformations reported for ST2 glassy water based on isothermal compression/decompression processes [Chiu et al., J. Chem. Phys. 139, 184504 (2013)]. The resulting phase diagram is consistent with the liquid-liquid phase transition hypothesis. At the same time, the glass phase diagram is sensitive to sample preparation, such as heating or compression rates. Interestingly, at least for the rates explored, our results suggest that the LDA-to-liquid (HDA-to-liquid) and LDA-to-HDA (HDA-to-LDA) transformation lines on heating are related

  11. Combination of ultrasound-assisted ionic liquid dispersive liquid-phase microextraction and high performance liquid chromatography for the sensitive determination of benzoylureas pesticides in environmental water samples.

    PubMed

    Zhou, Qingxiang; Zhang, Xiaoguo

    2010-12-01

    This paper describes a new method for rapid and sensitive determination of diflubenzuron, flufenoxuron, triflumuron and chlorfluazuron in water samples by ultrasound-assisted ionic liquid dispersive liquid-phase microextraction in combination with HPLC. Ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate ([C(6)MIM][PF(6)]) was used as the extraction solvent for the enrichment of four benzoylurea (BU) pesticides. Factors such as volume of [C(6)MIM][PF(6)], sonication time, sample pH, extraction time, centrifuging time and salting-out effect were systematically investigated. Under the optimum conditions, an excellent linear relationship was achieved in the range of 1.0-100 μg/L. The detection limits varied from 0.21 to 0.45 μg/L and the precision of the method was below 6.9% (RSD, n=6). The proposed method was successfully applied for the determination of these BU pesticides in water samples and excellent spiked recoveries were achieved. All these results demonstrated that this procedure provided a new simple, rapid, easy to operate, efficient and sensitive method for the analysis of BU pesticides in aqueous samples. PMID:21077128

  12. Dispersive liquid-liquid microextraction combined with ultra-high performance liquid chromatography for the simultaneous determination of 25 sulfonamide and quinolone antibiotics in water samples.

    PubMed

    Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Borges-Miquel, Teresa M; Rodríguez-Delgado, Miguel Ángel

    2013-03-01

    In this work, a dispersive liquid-liquid microextraction (DLLME) procedure combined with ultra-high performance liquid chromatography with diode-array detection was developed to determine 25 antibiotics in mineral and run-off waters. Optimum DLLME conditions (5 mL of water at pH=7.6, 20% (w/v) NaCl, 685 μL of CHCl₃ as extractant solvent, and 1250 μL of ACN as disperser solvent) allowed the repeatable, accurate and selective determination of 11 sulfonamides (sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfadimidin, sulfamethoxypyridazine, sulfadoxine, sulfamethoxazole, sulfisoxazole, sulfadimethoxine and sulfaquinoxaline) and 14 quinolones (pipemidic acid, marbofloxacin, fleroxacin, levofloxacin, pefloxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, difloxacin, moxifloxacin, oxolinic acid and flumequine). The method was validated by means of the obtention of calibration curves of the whole method as well as a recovery study at two levels of concentration. The LODs of the method were in the range 0.35-10.5 μg/L with recoveries between 78% and 117%. PMID:23246932

  13. Speciation of mercury in water samples by dispersive liquid-liquid microextraction combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Jia, Xiaoyu; Han, Yi; Liu, Xinli; Duan, Taicheng; Chen, Hangting

    2011-01-01

    The dispersive liquid-liquid microextraction (DLLME) combined with high performance liquid chromatography-inductively coupled plasma mass spectrometry for the speciation of mercury in water samples was described. Firstly methylmercury (MeHg +) and mercury (Hg 2+) were complexed with sodium diethyldithiocarbamate, and then the complexes were extracted into carbon tetrachloride by using DLLME. Under the optimized conditions, the enrichment factors of 138 and 350 for MeHg + and Hg 2+ were obtained from only 5.00 mL sample solution. The detection limits of the analytes (as Hg) were 0.0076 ng mL -1 for MeHg + and 0.0014 ng mL -1 for Hg 2+, respectively. The relative standard deviations for ten replicate measurements of 0.5 ng mL -1 MeHg + and Hg 2+ were 6.9% and 4.4%, respectively. Standard reference material of seawater (GBW(E)080042) was analyzed to verify the accuracy of the method and the results were in good agreement with the certified values. Finally, the developed method was successfully applied for the speciation of mercury in three environmental water samples.

  14. [Simultaneous determination of four phthalate esters in water samples using ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography].

    PubMed

    Ma, Yanling; Chen, Lingxin; Ding, Yangjun; Ming, Yongfei; Li, Jinhua

    2013-02-01

    Ultrasound-assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography (UA-DLLME-HPLC) was developed for the determination of four typical phthalate esters (PAEs). The analyzed PAEs included dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP) and di-n-octyl phthalate (DnOP). The UA-DLLME parameters such as types/volumes of extraction/dispersion solvents, ultrasonic time, ionic strength and extraction time, were investigated. Enrichment factor (EF)was employed to evaluate the extraction efficiency. The conditions were finally chosen: CCl4 (40 microL)/ acetonitrile (1.0 mL) as extraction/dispersion solvents; 30 g/L NaCl; ultrasound/centrifugation of 5 min. Under the optimized extraction conditions, UA-DLLME exhibited strong enrichment ability for the four PAEs. The EFs for DMP, DEP, DBP and DnOP obtained were 71, 144, 169 and 159, respectively. The limits of detection were 3.78, 1.77, 3.07 and 3.30 microg/L for DMP, DEP, DBP and DnOP, respectively. The satisfactory recoveries for three water samples at three spiked levels ranged from 82.99%-114.47%, with the relative standard deviations of 1.93%-8.31%. It is a convenient, speedy, environmentally benign method for the routine analysis of PAEs in water samples. PMID:23697182

  15. Determinations of cloud liquid water in the tropics from the SSM/I

    NASA Technical Reports Server (NTRS)

    Alishouse, John C.; Swift, Calvin; Ruf, Christopher; Snyder, Sheila; Vongsathorn, Jennifer

    1989-01-01

    Upward-looking microwave radiometric observations were used to validate the SSM/I determinations, and also as a basis for the determination of new coefficients. Due to insufficiency of the initial four channel algorithm for cloud liquid water, the improved algorithm was derived from the CORRAD (the University of Massachusetts autocorrelation radiometer) measurements of cloud liquid water and the matching SSM/I brightness temperatures using the standard linear regression. The correlation coefficients for the possible four channel combinations, and subsequently the best and the worst combinations were determined.

  16. Surfactant-induced nematic wetting layer at a thermotropic liquid crystal/water interface.

    PubMed

    Bahr, Ch

    2006-03-01

    An ellipsometric study of the interface between a thermotropic liquid crystal and water near the nematic-isotropic phase transition of the liquid crystal is presented. At temperatures above the transition, a nematic wetting layer appears at the interface if the water phase contains a surfactant inducing a homeotropic alignment of the nematic phase. The detailed behavior is significantly influenced by the concentration of the surfactant. The results can be described by a Landau model of nematic wetting in which the surfactant concentration tunes the magnitude of an ordering interface potential. PMID:16605490

  17. Measurement of liquid water content in a melting snowpack using cold calorimeter techniques

    NASA Technical Reports Server (NTRS)

    Rango, A.; Jones, E. B.; Howell, S.

    1980-01-01

    Liquid water in a snowpack is a quantifiable parameter of hydrological significance. It is also important in the interpretation of snowpack remote sensing data using microwave techniques. One acceptable approach to measuring liquid water content of a snowpack (by weight) is the cold calorimeter. This technique is presented from theory through application. Silicon oil was used successfully as the freezing agent. Consistent results can be obtained even when using operators with a minimum of training. Data can be obtained approximately every 15 minutes by using two calorimeters and three operators. Accuracy within one to two percent can be achieved under reasonable field conditions.

  18. Rapid determination of lead in water samples by dispersive liquid-liquid microextraction coupled with electrothermal atomic absorption spectrometry.

    PubMed

    Naseri, Mohammad Taghi; Hosseini, Mohammad Reza Milani; Assadi, Yaghoub; Kiani, Armin

    2008-03-15

    The need for highly reliable methods for the determination of trace and ultratrace elements has been recognized in analytical chemistry and environmental science. A simple and powerful microextraction technique was used for the detection of the lead ultratrace amounts in water samples using the dispersive liquid-liquid microextraction (DLLME), followed by the electrothermal atomic absorption spectrometry (ET AAS). In this microextraction technique, a mixture of 0.50 mL acetone (disperser solvent), containing 35 microL carbon tetrachloride (extraction solvent) and 5 microL diethyldithiophosphoric acid (chelating agent), was rapidly injected by syringe into the 5.00 mL water sample, spiked with lead. In this process, the lead ions reacted with the chelating agent and were extracted into the fine droplets of CCl(4). After centrifugation (2 min at 5000 rpm), the fine CCl4 droplets were sedimented at the bottom of the conical test tube (25+/-1 microL). Then, 20 microL from the sedimented phase, containing the enriched analyte, was determined by ET AAS. The next step was the optimization of various experimental conditions, affecting DLLME, such as the type and the volume of the extraction solvent, the type and the volume of the disperser solvent, the extraction time, the salt effect, pH and the chelating agent amount. Moreover, the effect of the interfering ions on the analytes recovery was also investigated. Under the optimum conditions, the enrichment factor of 150 was obtained from only a 5.00 mL water sample. The calibration graph was linear in the range of 0.05-1 microg L(-1) with the detection limit of 0.02 microg L(-1). The relative standard deviation (R.S.D.) for seven replicate measurements of 0.50 microg L(-1) of lead was 2.5%. The relative lead recoveries in mineral, tap, well and sea water samples at the spiking level of 0.20 and 0.40 microg L(-1) varied from 93.5 to 105.0. The characteristics of the proposed method were compared with the cloud point

  19. On the existence and stability of liquid water on the surface of mars today

    NASA Technical Reports Server (NTRS)

    Kuznetz, L. H.; Gan, D. C.

    2002-01-01

    The recent discovery of high concentrations of hydrogen just below the surface of Mars' polar regions by Mars Odyssey has enlivened the debate about past or present life on Mars. The prevailing assumption prior to the discovery was that the liquid water essential for its existence is absent. That assumption was based largely on the calculation of heat and mass transfer coefficients or theoretical climate models. This research uses an experimental approach to determine the feasibility of liquid water under martian conditions, setting the stage for a more empirical approach to the question of life on Mars. Experiments were conducted in three parts: Liquid water's existence was confirmed by droplets observed under martian conditions in part 1; the evolution of frost melting on the surface of various rocks under martian conditions was observed in part 2; and the evaporation rate of water in Petri dishes under Mars-like conditions was determined and compared with the theoretical predictions of various investigators in part 3. The results led to the conclusion that liquid water can be stable for extended periods of time on the martian surface under present-day conditions.

  20. Thrust Performance Improvement for a Water/Liquid Nitrogen Rocket Engine

    NASA Astrophysics Data System (ADS)

    Watanabe, Rikio; Mikami, Ryo

    We propose a water/liquid nitrogen rocket engine as a new non-combustion type rocket engine. Liquid nitrogen is mixed with heated water and specific volume of nitrogen is increased by evaporation. Thrust force is obtained by exhaust of nitrogen gas through a nozzle with water particles. Results of previous experiments indicated a specific impulse is 60 % of the theoretically estimated value. By evaluating the characteristic exhaust velocity and other thrust characteristics, we found that the lower-than-expected specific impulse is due to insufficient propellant mixing and heat transfer between heated water and liquid nitrogen in the mixing chamber. We also performed high-speed imaging experiments to visualize impinging and mixing of propellants. Results indicate that in the original injection setup, heat conveyed by heated water is not adequately transferred to the liquid nitrogen. An alternative injection pattern was tested, which resulted in a 10% increase in the characteristic exhaust velocity. In addition, we tested a new type of injector designed for more efficient mixing and heat transfer that exhibited 30 % increase in characteristic exhaust velocity. Furthermore, we modified the theoretical expression for the characteristic exhaust velocity based on multi-phased flow theory so that it agrees well with the experimental results.

  1. An Integrated Approach toward Retrieving Physically Consistent Profiles of Temperature, Humidity, and Cloud Liquid Water.

    NASA Astrophysics Data System (ADS)

    Löhnert, Ulrich; Crewell, Susanne; Simmer, Clemens

    2004-09-01

    A method is presented for deriving physically consistent profiles of temperature, humidity, and cloud liquid water content. This approach combines a ground-based multichannel microwave radiometer, a cloud radar, a lidar-ceilometer, the nearest operational radiosonde measurement, and ground-level measurements of standard meteorological properties with statistics derived from results of a microphysical cloud model. All measurements are integrated within the framework of optimal estimation to guarantee a retrieved profile with maximum information content. The developed integrated profiling technique (IPT) is applied to synthetic cloud model output as a test of accuracy. It is shown that the liquid water content profiles obtained with the IPT are significantly more accurate than common methods that use the microwave-derived liquid water path to scale the radar reflectivity profile. The IPT is also applied to 2 months of the European Cloud Liquid Water Network (CLIWA-NET) Baltic Sea Experiment (BALTEX) BRIDGE main experiment (BBC) campaign data, considering liquid-phase, nonprecipitating clouds only. Error analysis indicates root-mean-square uncertainties of less than 1 K in temperature and less than 1 g m-3 in humidity, where the relative error in liquid water content ranges from 15% to 25%. A comparison of the vertically integrated humidity profile from the IPT with the nearest operational radiosonde shows an acceptable bias error of 0.13 kg m-2 when the Rosenkranz gas absorption model is used. However, if the Liebe gas absorption model is used, this systematic error increases to -1.24 kg m-2, showing that the IPT humidity retrieval is significantly dependent on the chosen gas absorption model.


  2. Effect of simple solutes on the long range dipolar correlations in liquid water

    NASA Astrophysics Data System (ADS)

    Baul, Upayan; Kanth, J. Maruthi Pradeep; Anishetty, Ramesh; Vemparala, Satyavani

    2016-03-01

    Intermolecular correlations in liquid water at ambient conditions have generally been characterized through short range density fluctuations described through the atomic pair distribution functions. Recent numerical and experimental results have suggested that such a description of order or structure in liquid water is incomplete and there exist considerably longer ranged orientational correlations in water that can be studied through dipolar correlations. In this study, using large scale classical, atomistic molecular dynamics simulations using TIP4P-Ew and TIP3P models of water, we show that salts such as sodium chloride (NaCl), potassium chloride (KCl), caesium chloride (CsCl), and magnesium chloride (MgCl2) have a long range effect on the dipolar correlations, which cannot be explained by the notion of structure making and breaking by dissolved ions. Observed effects are explained through orientational stratification of water molecules around ions and their long range coupling to the global hydrogen bond network by virtue of the sum rule for water. The observations for single hydrophilic solutes are contrasted with the same for a single methane (CH4) molecule. We observe that even a single small hydrophobe can result in enhancement of long range orientational correlations in liquid water, contrary to the case of dissolved ions, which have been observed to have a reducing effect. The observations from this study are discussed in the context of hydrophobic effect.

  3. A Combined Experimental and Molecular Dynamics Study of Iodide-Based Ionic Liquid and Water Mixtures.

    PubMed

    Nickerson, Stella D; Nofen, Elizabeth M; Chen, Haobo; Ngan, Miranda; Shindel, Benjamin; Yu, Hongyu; Dai, Lenore L

    2015-07-16

    Iodide-based ionic liquids have been widely employed as iodide sources in electrolytes for applications utilizing the triiodide/iodide redox couple. While adding a low-viscosity solvent such as water to ionic liquids can greatly enhance their usefulness, mixtures of highly viscous iodide-containing ILs with water have never been studied. This paper investigates, for the first time, mixtures of water and the ionic liquid 1-butyl-3-methylimidazolium iodide ([BMIM][I]) through a combined experimental and molecular dynamics study. The density, melting point, viscosity, and conductivity of these mixtures were measured by experiment. The composition region below 50% water by mole was found to differ dramatically from the region above 50% water, with trends in density and melting point differing before and after that point. Water was found to have a profound effect on viscosity and conductivity of the IL, and the effect of hydrogen bonding was discussed. Molecular dynamics simulations representing the same mixture compositions were performed. Molecular ordering was observed, as were changes in this ordering corresponding to water content. Molecular ordering was related to the experimentally measured mixture properties, providing a possible explanation for the two distinct composition regions identified by experiment. PMID:26090562

  4. Effect of simple solutes on the long range dipolar correlations in liquid water.

    PubMed

    Baul, Upayan; Kanth, J Maruthi Pradeep; Anishetty, Ramesh; Vemparala, Satyavani

    2016-03-14

    Intermolecular correlations in liquid water at ambient conditions have generally been characterized through short range density fluctuations described through the atomic pair distribution functions. Recent numerical and experimental results have suggested that such a description of order or structure in liquid water is incomplete and there exist considerably longer ranged orientational correlations in water that can be studied through dipolar correlations. In this study, using large scale classical, atomistic molecular dynamics simulations using TIP4P-Ew and TIP3P models of water, we show that salts such as sodium chloride (NaCl), potassium chloride (KCl), caesium chloride (CsCl), and magnesium chloride (MgCl2) have a long range effect on the dipolar correlations, which cannot be explained by the notion of structure making and breaking by dissolved ions. Observed effects are explained through orientational stratification of water molecules around ions and their long range coupling to the global hydrogen bond network by virtue of the sum rule for water. The observations for single hydrophilic solutes are contrasted with the same for a single methane (CH4) molecule. We observe that even a single small hydrophobe can result in enhancement of long range orientational correlations in liquid water, contrary to the case of dissolved ions, which have been observed to have a reducing effect. The observations from this study are discussed in the context of hydrophobic effect. PMID:26979692

  5. Two-state thermodynamics and the possibility of a liquid-liquid phase transition in supercooled TIP4P/2005 water.

    PubMed

    Singh, Rakesh S; Biddle, John W; Debenedetti, Pablo G; Anisimov, Mikhail A

    2016-04-14

    Water shows intriguing thermodynamic and dynamic anomalies in the supercooled liquid state. One possible explanation of the origin of these anomalies lies in the existence of a metastable liquid-liquid phase transition (LLPT) between two (high and low density) forms of water. While the anomalies are observed in experiments on bulk and confined water and by computer simulation studies of different water-like models, the existence of a LLPT in water is still debated. Unambiguous experimental proof of the existence of a LLPT in bulk supercooled water is hampered by fast ice nucleation which is a precursor of the hypothesized LLPT. Moreover, the hypothesized LLPT, being metastable, in principle cannot exist in the thermodynamic limit (infinite size, infinite time). Therefore, computer simulations of water models are crucial for exploring the possibility of the metastable LLPT and the nature of the anomalies. In this work, we present new simulation results in the NVT ensemble for one of the most accurate classical molecular models of water, TIP4P/2005. To describe the computed properties and explore the possibility of a LLPT, we have applied two-structure thermodynamics, viewing water as a non-ideal mixture of two interconvertible local structures ("states"). The results suggest the presence of a liquid-liquid critical point and are consistent with the existence of a LLPT in this model for the simulated length and time scales. We have compared the behavior of TIP4P/2005 with other popular water-like models, namely, mW and ST2, and with real water, all of which are well described by two-state thermodynamics. In view of the current debate involving different studies of TIP4P/2005, we discuss consequences of metastability and finite size in observing the liquid-liquid separation. We also address the relationship between the phenomenological order parameter of two-structure thermodynamics and the microscopic nature of the low-density structure. PMID:27083735

  6. Comment on "Structure and dynamics of liquid water on rutile TiO2(110)

    SciTech Connect

    Wesolowski, David J; Sofo, Jorge O.; Bandura, Andrei V.; Zhang, Zhan; Mamontov, Eugene; Predota, M.; Kumar, Nitin; Kubicki, James D.; Kent, Paul R; Vlcek, Lukas; Machesky, Michael L.; Fenter, Paul; Cummings, Peter T; Anovitz, Lawrence {Larry} M; Skelton, A A; Rosenqvist, Jorgen K

    2012-01-01

    Liu and co-workers [Phys. Rev. B 82, 161415 (2010)] discussed the long-standing debate regarding whether H2O molecules on the defect-free (110) surface of rutile ( -TiO2) sorb associatively, or there is dissociation of some or all first-layer water to produce hydroxyl surface sites. They conducted static density functional theory (DFT) and DFT molecular dynamics (DFT-MD) investigations using a range of cell configurations and functionals. We have reproduced their static DFT calculations of the influence of crystal slab thickness on water sorption energies. However, we disagree with several assertions made by these authors: (a) that second-layer water structuring and hydrogen bonding to surface oxygens and adsorbed water molecules are weak ; (b) that translational diffusion of water molecules in direct contact with the surface approaches that of bulk liquid water; and (c) that there is no dissociation of adsorbed water at this surface in contact with liquid water. These assertions directly contradict our publishedwork, which compared synchrotron x-ray crystal truncation rod, second harmonic generation, quasielastic neutron scattering, surface charge titration, and classical MD simulations of rutile (110) single-crystal surfaces and (110)-dominated powders in contact with bulk water, and (110)-dominated rutile nanoparticles with several monolayers of adsorbed water.

  7. Hydrogen Bonding in Liquid Water and in the Hydration Shell of Salts.

    PubMed

    Dagade, Dilip H; Barge, Seema S

    2016-03-16

    A near-IR spectral study on pure water and aqueous salt solutions is used to investigate stoichiometric concentrations of different types of hydrogen-bonded water species in liquid water and in water comprising the hydration shell of salts. Analysis of the thermodynamics of hydrogen-bond formation signifies that hydrogen-bond making and breaking processes are dominated by enthalpy with non-negligible heat capacity effects, as revealed by the temperature dependence of standard molar enthalpies of hydrogen-bond formation and from analysis of the linear enthalpy-entropy compensation effects. A generalized method is proposed for the simultaneous calculation of the spectrum of water in the hydration shell and hydration number of solutes. Resolved spectra of water in the hydration shell of different salts clearly differentiate hydrogen bonding of water in the hydration shell around cations and anions. A comparison of resolved liquid water spectra and resolved hydration-shell spectra of ions highlights that the ordering of absorption frequencies of different kinds of hydrogen-bonded water species is also preserved in the bound state with significant changes in band position, band width, and band intensity because of the polarization of water molecules in the vicinity of ions. PMID:26749515

  8. Measurement of Water Fraction in Liquid Hydro-Carbons Using ECT Sensor

    NASA Astrophysics Data System (ADS)

    Bukhari, Syed Faisal Ahmed; Ismail, Idris; Yang, Wuqiang

    2007-06-01

    In the oil industry, it is important to measure the water fraction in liquid hydrocarbons in oil pipelines for optimising operation and transportation, e.g. loading/unloading of oil tankers, where the flow rate is variable. As a feasibility study an electrical capacitance tomography (ECT) sensor has been used for on-line water fraction measurement. Data from different electrode combinations, e.g. adjacent electrodes and opposite electrodes are combined. Preliminary results indicate that ECT can be used for measuring the fraction of water in oil with 0.05% error in a range of water-in-oil up to 10%.

  9. EVALUATION OF A TEFLON HELIX LIQUID-LIQUID EXTRACTOR FOR CONCENTRATION OF TRACE ORGANICS FROM WATER INTO METHYLENE CHLORIDE (JOURNAL VERSION)

    EPA Science Inventory

    A continuous liquid-liquid extraction system (CLLE) for concentrating trace organics from water into methylene chloride for analysis was designed, built and evaluated. The CLLE uses Teflon coils for phase contact and gravity phase separation. The system includes a self-contained ...

  10. Mars Gully: No Mineral Trace of Liquid Water

    NASA Technical Reports Server (NTRS)

    2007-01-01

    This image of the Centauri-Hellas Montes region was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 2107 UTC (4:07 p.m. EST) on Jan. 9, 2007, near 38.41 degrees south latitude, 96.81 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. The region covered is slightly wider than 10 kilometers (6.2 miles) at its narrowest point.

    Narrow gullies found on hills and crater walls in many mid-latitude regions of Mars have been interpreted previously as cut by geologically 'recent' running water, meaning water that flowed on Mars long after impact cratering, tectonic forces, volcanism or other processes created the underlying landforms. Some gullies even eroded into sand dunes, which would date their formation at thousands to millions of years ago, or less. In fact, Mars Orbiter Camera (MOC) images showed two of the gullies have bright deposits near their downslope ends - but those deposits were absent in images taken just a few years earlier. The bright deposits must have formed within the period 1999-2004.

    Has there been running water on Mars so recently? To address that question, CRISM and MRO's other instruments observed the bright gully deposits. CRISM's objective was to determine if the bright deposits contained salts left behind from water evaporating into Mars' thin air. The high-resolution imager's (HiRISE's) objective was to determine if the small-scale morphology was consistent with formation by running water.

    This CRISM image of a bright gully deposit was constructed by showing 2.53, 1.50, and 1.08 micrometer light in the red, green, and blue image planes. CRISM can just resolve the deposits (highlighted by arrows in the inset), which are only a few tens of meters (about 150 feet) across. The spectrum of the deposits barely differs from that of the surrounding material, and is just a little brighter. This difference

  11. Water-free rare-earth-metal ionic liquids/ionic liquid crystals based on hexanitratolanthanate(III) anion.

    PubMed

    Ji, Shun-Ping; Tang, Meng; He, Ling; Tao, Guo-Hong

    2013-04-01

    The hexanitratolanthanate anion (La(NO(3))(6)(3-)) is an interesting symmetric anion suitable to construct the component of water-free rare-earth-metal ionic liquids. The syntheses and structural characterization of eleven lanthanum nitrate complexes, [C(n)mim](3)[La(NO(3))(6)] (n=1, 2, 4, 6, 8, 12, 14, 16, 18), including 1,3-dimethylimidazolium hexanitratolanthanate ([C(1)mim](3)[La(NO(3))(6)], 1), 1-ethyl-3-methylimidazolium hexanitratolanthanate ([C(2)mim](3)[La(NO(3))(6)], 2), 1-butyl-3-methylimidazolium hexanitratolanthanate ([C(4)mim](3)[La(NO(3))(6)], 3), 1-isobutyl-3-methylimidazolium hexanetratolanthanate ([isoC(4)mim](3)[La(NO(3))(6)], 4), 1-methyl-3-(3'-methylbutyl)imidazolium hexanitratolanthanate ([MC(4)mim](3)[La(NO(3))(6)], 5), 1-hexyl-3-methylimidazolium hexanitratolanthanate ([C(6)mim](3)[La(NO(3))(6)], 6), 1-methyl-3-octylimidazolium hexanitratolanthanate ([C(8)mim](3)[La(NO(3))(6)], 7), 1-dodecyl-3-methylimidazolium hexanitratolanthanate ([C(12)mim](3)[La(NO(3))(6)], 8), 1-methyl-3-tetradecylimidazolium hexanitratolanthanate ([C(14)mim](3)[La-(NO(3))(6)], 9), 1-hexadecyl-3-methylimid-azolium hexanitratolanthanum ([C(16)dmim](3)[La(NO(3))(6)], 10), and 1-methyl-3-octadecylimidazolium hexanitratolanthanate ([C(18)mim](3)[La(NO(3))(6)], 11) are reported. All new compounds were characterized by (1)H and (13)C NMR, and IR spectroscopy as well as elemental analysis. The crystal structure of compound 1 was determined by using single-crystal X-ray diffraction, giving the following crystallographic information: monoclinic; P2(1)/c; a=15.3170 (3), b=14.2340 (2), c=13.8954(2) Å; β=94.3453(15)°, V=3020.80(9) Å(3), Z=4, ρ=1.764 g cm(-3). The coordination polyhedron around the lanthanum ion is rationalized by six nitrate anions with twelve oxygen atoms. No hydrogen-bonding network or water molecule was found in 1. The thermodynamic stability of the new complexes was investigated by using thermogravimetric analysis (TGA). The water

  12. Dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometry: ultra trace determination of cadmium in water samples.

    PubMed

    Zeini Jahromi, Elham; Bidari, Araz; Assadi, Yaghoub; Milani Hosseini, Mohammad Reza; Jamali, Mohammad Reza

    2007-03-01

    Dispersive liquid-liquid microextraction (DLLME) technique was successfully used as a sample preparation method for graphite furnace atomic absorption spectrometry (GF AAS). In this extraction method, 500 microL methanol (disperser solvent) containing 34 microL carbon tetrachloride (extraction solvent) and 0.00010 g ammonium pyrrolidine dithiocarbamate (chelating agent) was rapidly injected by syringe into the water sample containing cadmium ions (interest analyte). Thereby, a cloudy solution formed. The cloudy state resulted from the formation of fine droplets of carbon tetrachloride, which have been dispersed, in bulk aqueous sample. At this stage, cadmium reacts with ammonium pyrrolidine dithiocarbamate, and therefore, hydrophobic complex forms which is extracted into the fine droplets of carbon tetrachloride. After centrifugation (2 min at 5000 rpm), these droplets were sedimented at the bottom of the conical test tube (25+/-1 microL). Then a 20 microL of sedimented phase containing enriched analyte was determined by GF AAS. Some effective parameters on extraction and complex formation, such as extraction and disperser solvent type and their volume, extraction time, salt effect, pH and concentration of the chelating agent have been optimized. Under the optimum conditions, the enrichment factor 125 was obtained from only 5.00 mL of water sample. The calibration graph was linear in the rage of 2-20 ng L(-1) with detection limit of 0.6 ng L(-1). The relative standard deviation (R.S.D.s) for ten replicate measurements of 20 ng L(-1) of cadmium was 3.5%. The relative recoveries of cadmium in tap, sea and rivers water samples at spiking level of 5 and 10 ng L(-1) are 108, 95, 87 and 98%, respectively. The characteristics of the proposed method have been compared with cloud point extraction (CPE), on-line liquid-liquid extraction, single drop microextraction (SDME), on-line solid phase extraction (SPE) and co-precipitation based on bibliographic data. Therefore, DLLME

  13. Obtaining of gas, liquid, and upgraded solid fuel from brown coals in supercritical water

    NASA Astrophysics Data System (ADS)

    Vostrikov, A. A.; Fedyaeva, O. N.; Dubov, D. Yu.; Shishkin, A. V.; Sokol, M. Ya.

    2013-12-01

    Two new conversion methods of brown coals in water steam and supercritical water (SCW) are proposed and investigated. In the first method, water steam or SCW is supplied periodically into the array of coal particles and then is ejected from the reactor along with dissolved conversion products. The second method includes the continuous supply of water-coal suspension (WCS) into the vertically arranged reactor from above. When using the proposed methods, agglomeration of coal particles is excluded and a high degree of conversion of coal into liquid and gaseous products is provided. Due to the removal of the main mass of oxygen during conversion in the composition of CO2, the high heating value of fuels obtained from liquid substantially exceeds this characteristic of starting coal. More than half of the sulfur atoms transfer into H2S during the SCW conversion already at a temperature lower than 450°C.

  14. One-Way Diffusion of Ionic Liquids in a Mixing Process with Water

    NASA Astrophysics Data System (ADS)

    Oikawa, Noriko; Tahara, Daiki; Kurita, Rei

    2016-09-01

    In contrast to the usual diffusive mixing process between two miscible liquids, the ionic liquid [Cnmim][PF6] forms a droplet in water while mixing. The droplet retains a sharp interface with surface tension, gradually decreasing in size until completely mixed with water. This peculiar behavior in the mixing process accompanies one-way diffusion, in which ions diffuse in one direction only from the bulk IL droplet into the bulk continuum of water. The activation energy of the one-way diffusion at the [Cnmim][PF6]/water interface increases with increasing length of the hydrophobic alkyl chains attached to the cation molecules of [Cnmim][PF6]. It is considered that the hydrophobic nanoscale structure observed in [C4mim][PF6] plays an important role in the generation of the droplet and the mixing dynamics.

  15. The Streaming Potential Coupling Coefficient of Liquid Carbon Dioxide Injected Into Water Saturated Berea Sandstone

    NASA Astrophysics Data System (ADS)

    Moore, J. R.; Glaser, S. D.; Morrison, H. F.

    2003-12-01

    The streaming potential coupling coefficient was determined for a liquid carbon dioxide flood of a water-saturated sample of Berea sandstone. The coupling coefficient for the rock/water case was determined both before and after each CO2 flood of three samples using a low-pressure static head method. Next, liquid CO2 was allowed to flow through each sample. As the CO2 displaced the water the coupling coefficient decreased. At longer times, when all mobile pore water was displaced, the coupling coefficient maintained a steady state, and was lower than that for water by about 10 times. The results of this testing reveal a coupling coefficient of 30 mV/0.1MPa, for 125 Ohm-m water flow through the sample, and 3.0 mV / 0.1 MPa for liquid CO2 flow. Calculated zeta potentials are -3.4 mV using water as the pore fluid and -1.7 x 10-6 mV for liquid CO2. We propose that the lower coupling coefficient for CO2 flow is primarily a result of changes in zeta potential, since changes in pore fluid resistivity and viscosity would act to increase the coupling coefficient. Zeta potential for the liquid CO2 / mineral interface is a function of the low polarity and lack of mobile ions associated with liquid CO2. We find no anomalous 2-phase liquid/gas effects, which may have augmented single-phase streaming potentials by many times. We propose that although CO2 gas may have been present for some of the higher pressure drop events, the low gas fraction (or quality) of the two-phase mixture did not lead to any significant anomalous or augmented observations. Implications of this work include spatial and temporal monitoring of CO2 injectate in subsurface reservoirs and the identification of flow paths, with the recommendation being to attempt to image the advancing CO2/water front, where the coupling coefficient is higher.

  16. Potential transient liquid water flow features in fresh craters on Vesta

    NASA Astrophysics Data System (ADS)

    Scully, J. E.; Yin, A.; Russell, C. T.; Denevi, B. W.; Reddy, V.

    2012-12-01

    Observations made by the Dawn spacecraft reveal unexpected potential transient liquid water flow features (PTFs) in fresh craters on Vesta. The PTFs have features similar to the headward alcoves, channels and distal aprons of the Martian gullies and related features on Earth (e.g. Malin & Edgett 2000), and have been identified in multiple Vestan craters. All of the craters have relatively fresh rims, which suggests that they, and the PTFs, formed relatively recently in the history of Vesta's evolution. There is some correlation between craters that contain PTFs and craters that contain pitted terrain, which Denevi et al. (2012) propose formed as volatile-bearing material degassed after being heated by an impact. Cornelia crater contains good examples of PTFs and a geological map was made of Cornelia crater based on ~20 m/pixel resolution images. Cross-cutting relationships derived from the map make it is possible to discern a geological history: firstly, an early damp stage, during which the PTFs formed; secondly, a transitional damp to dry stage, during which the pitted terrain formed and thirdly, a dry stage. There is considerable morphological evidence that the formation of the PTFs in Cornelia was by flow of liquid water and not by dry granular flow, flow of impact melt or flow of liquid CO2. The channels are not as sinuous as those on the Earth and Mars, but the fact that the PTFs formed on the relatively high slopes of the crater walls and under conditions of Vesta's low gravity, means that the channels may not need to divert around obstacles. The PTFs in Cornelia crater tend to form in the dark material dominated areas of the crater, which Reddy et al. (2012) conclude has a composition similar to carbonaceous chondrite (CC) and think originates from the impactor that formed Vesta's Veneneia impact basin. Vesta's current surface temperatures and pressures make it an inhospitable environment for liquid water. But, energy from a high velocity impactor that

  17. Determination of lead in environmental waters with dispersive liquid-liquid microextraction prior to atomic fluorescence spectrometry.

    PubMed

    Zhou, Qingxiang; Zhao, Na; Xie, Guohong

    2011-05-15

    This paper established a new, rapid and sensitive method for the determination of lead in water samples preconcentrated by dispersive liquid-liquid microextraction (DLLME) prior to atomic fluorescence spectrometry. Dithizone was used as the chelating agent. In the DLLME procedure, lead formed lead-dithizone complex and migrated into the carbon tetrachloride micro-droplets. Important factors that would affect the extraction efficiency had been investigated including the kind and volume of extraction solvent and dispersive solvent, sample pH, the amount of chelating agent, extraction time and centrifugation time. The results showed that the coexisting ions containing in water samples had no obvious negative effect on the determination of lead. The experimental results indicated that the proposed method had a good linear range of 0.01-100 ng mL(-1) (r(2) = 0.9990). The precision was 2.12% (RSD, n = 7) and the detection limit was 0.95 ng L(-1). Proposed method was validated with four real environmental samples and the results indicated that the proposed method was excellent for the future use and satisfied spiked recoveries were in the range of 92.9-97.4%. PMID:21398026

  18. Dispersive liquid-liquid microextraction combined with nonaqueous capillary electrophoresis for the determination of fluoroquinolone antibiotics in waters.

    PubMed

    Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Borges-Miquel, Teresa M; Rodríguez-Delgado, Miguel Á

    2010-10-01

    Dispersive liquid-liquid microextraction (DLLME) was combined for the first time with NACE-UV for the selective determination of eight fluoroquinolone antibiotics (lomefloxacin, levofloxacin, marbofloxacin, ciprofloxacin, sarafloxacin, enrofloxacin, danofloxacin and difloxacin) in mineral and run-off waters. Field-enhanced sample injection was carried out in order to improve the sensitivity, whereas pipemidic acid was used as internal standard. The BGE that provided complete separation of the eight analytes and the internal standard was composed of 3 M acetic acid, 49 mM ammonium acetate in 55:45 v/v methanol:ACN. Optimum DLLME conditions (extraction of 5 mL of water at pH 7.6 with 685 μL of CHCl(3) and 1250 μL of ACN, extractant and disperser solvents, respectively) were achieved by means of experimental design methodology. Calibration curves of the whole method were obtained with correlation coefficients (R) higher than 0.994 in all cases. An accuracy and precision study was carried out at different levels of concentration, finding that there were no significant differences (Student's t-test) between real and spiked concentrations. PMID:20859952

  19. Automated high performance liquid chromatography and liquid scintillation counting determination of pesticide mixture octanol/water partition rates

    SciTech Connect

    Moody, R.P.; Carroll, J.M.; Kresta, A.M.

    1987-12-01

    Two novel methods are reported for measuring octanol/water partition rates of pesticides. A liquid scintillation counting (LSC) method was developed for automated monitoring of /sup 14/C-labeled pesticides partitioning in biphasic water/octanol cocktail systems with limited success. A high performance liquid chromatography (HPLC) method was developed for automated partition rate monitoring of several constituents in a pesticide mixture, simultaneously. The mean log Kow +/- SD determined from triplicate experimental runs were for: 2,4-D-DMA (2,4-dichlorophenoxyacetic acid dimethylamine), 0.65 +/- .17; Deet (N,N-diethyl-m-toluamide), 2.02 +/- .01; Guthion (O,O-dimethyl-S-(4-oxo-1,2,3-benzotriazin-3(4H)-ylmethyl) phosphorodithioate), 2.43 +/- .03; Methyl-Parathion (O,O-dimethyl-O-(p-nitrophenyl) phosphorothioate), 2.68 +/- .05; and Fenitrothion (O,O-dimethyl O-(4-nitro-m-tolyl) phosphorothioate), 3.16 +/- .03. A strong positive linear correlation (r = .9979) was obtained between log Kow and log k' (log Kow = 2.35 (log k') + 0.63). The advantages that this automated procedure has in comparison with the standard manual shake-flask procedure are discussed.

  20. In situ metathesis ionic liquid formation dispersive liquid-liquid microextraction for copper determination in water samples by electrothermal atomic absorption spectrometry.

    PubMed

    Stanisz, Ewa; Zgoła-Grześkowiak, Agnieszka

    2013-10-15

    In situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with electrothermal atomic absorption spectrometry (ET AAS) for determination of copper in water samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination by AAS. Some essential parameters of the microextraction and detection techniques such as the pH of sample solution, volume of components for in situ synthesis, matrix interferences and main parameters of graphite furnace atomizer have been studied. Under optimal conditions, high extraction efficiency for copper was achieved for the extraction of 0.7 µg L(-1) in 10.0 mL of sample solution employing 8 μL of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) as the extraction solvent. The detection limit was found as 0.004 µg L(-1) with an enrichment factor of 200. The relative standard deviation (RSD) for seven replicate measurements of 0.7 µg L(-1) in sample solution was 4%. The accuracy of the proposed method was evaluated by analysis of the Certified Reference Materials: NIST SRM 2709 (San Joaquin Soil), NBS SRM 2704 (Buffalo River Sediment), NRCC DOLT-2 (Dogfish Liver) and NIST SRM 1643e (Trace Element in Water). The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the tap, lake and mineral water samples. PMID:24054576

  1. Determination of aqueous fullerene aggregates in water by ultrasound-assisted dispersive liquid-liquid microextraction with liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry.

    PubMed

    Chen, Hsin-Chang; Ding, Wang-Hsien

    2012-02-01

    A simple and solvent-minimized method for the determination of three aqueous fullerene aggregates (nC₆₀, nC₇₀, and aqueous [6,6]-phenyl C₆₁ butyric acid methyl ester (nPCBM)) in water samples is described. The method involves the use of ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled liquid chromatography-tandem mass spectrometry with atmospheric pressure photoionization (LC-APPI-MS/MS). The parameters affecting the extraction efficiency of the analytes from water samples were systematically investigated and the conditions optimized. The best extraction conditions involved the rapid injection of a mixture of 1.0 mL of 2-propanol (as a disperser solvent) and 10 μL of benzyl bromide (as an extraction solvent) into 10 mL of an aqueous solution (pH 10.0) containing 1% sodium chloride in a conical bottom glass tube. After ultrasonication for 1.0 min and centrifugation at 5000 pm (10 min), the sedimented phase 5.0 μL was directly injected into the LC-APPI-MS/MS system. The limits of quantification (LOQs) were 150, 60 and 8 ng L⁻¹ for nPCBM, nC₆₀ and nC₇₀, respectively. The precision for these analytes, as indicated by relative standard deviations (RSDs), were less than 12% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 70 and 86%. A standard addition method was used to quantitate three aqueous fullerene aggregates, and the concentrations of these aqueous fullerene aggregates were determined to be in the range from n.d. to 130 ng L⁻¹ in various environmental samples including municipal influent and effluent samples, industrial wastewater samples, and surface water samples. PMID:22209304

  2. Scattering of water from the glycerol liquid-vacuum interface

    NASA Technical Reports Server (NTRS)

    Benjamin, I.; Wilson, M. A.; Pohorille, A.; Nathanson, G. M.

    1995-01-01

    Molecular dynamics calculations of the scattering of D2O from the glycerol surface at different collision energies are reported. The results for the trapping probabilities and energy transfer are in good agreement with experiments. The calculations demonstrate that the strong attractive forces between these two strongly hydrogen bonding molecules have only a minor effect on the initial collision dynamics. The trapping probability is influenced to a significant extent by the repulsive hard sphere-like initial encounter with the corrugated surface and, only at a later stage, by the efficiency of energy flow in the multiple interactions between the water and the surface molecules.

  3. Sub- and super-Maxwellian evaporation of simple gases from liquid water

    NASA Astrophysics Data System (ADS)

    Kann, Z. R.; Skinner, J. L.

    2016-04-01

    Non-Maxwellian evaporation of light atoms and molecules (particles) such as He and H2 from liquids has been observed experimentally. In this work, we use simulations to study systematically the evaporation of Lennard-Jones particles from liquid water. We find instances of sub- and super-Maxwellian evaporation, depending on the mass of the particle and the particle-water interaction strength. The observed trends are in qualitative agreement with experiment. We interpret these trends in terms of the potential of mean force and the effectiveness and frequency of collisions during the evaporation process. The angular distribution of evaporating particles is also analyzed, and it is shown that trends in the energy from velocity components tangential and normal to the liquid surface must be understood separately in order to interpret properly the angular distributions.

  4. Sub- and super-Maxwellian evaporation of simple gases from liquid water.

    PubMed

    Kann, Z R; Skinner, J L

    2016-04-21

    Non-Maxwellian evaporation of light atoms and molecules (particles) such as He and H2 from liquids has been observed experimentally. In this work, we use simulations to study systematically the evaporation of Lennard-Jones particles from liquid water. We find instances of sub- and super-Maxwellian evaporation, depending on the mass of the particle and the particle-water interaction strength. The observed trends are in qualitative agreement with experiment. We interpret these trends in terms of the potential of mean force and the effectiveness and frequency of collisions during the evaporation process. The angular distribution of evaporating particles is also analyzed, and it is shown that trends in the energy from velocity components tangential and normal to the liquid surface must be understood separately in order to interpret properly the angular distributions. PMID:27389228

  5. Interaction of a sodium ion with the water liquid-vapor interface

    NASA Technical Reports Server (NTRS)

    Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

    1989-01-01

    Molecular dynamics results are presented for the density profile of a sodium ion near the water liquid-vapor interface at 320 K. These results are compared with the predictions of a simple dielectric model for the interaction of a monovalent ion with this interface. The interfacial region described by the model profile is too narrow and the profile decreases too abruptly near the solution interface. Thus, the simple model does not provide a satisfactory description of the molecular dynamics results for ion positions within two molecular diameters from the solution interface where appreciable ion concentrations are observed. These results suggest that surfaces associated with dielectric models of ionic processes at aqueous solution interfaces should be located at least two molecular diameters inside the liquid phase. A free energy expense of about 2 kcal/mol is required to move the ion within two molecular layers of the free water liquid-vapor interface.

  6. Experimental, Numerical, and Analytical Slosh Dynamics of Water and Liquid Nitrogen in a Spherical Tank

    NASA Technical Reports Server (NTRS)

    Storey, Jedediah Morse

    2016-01-01

    Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving performance of space missions when a significant percentage of the spacecraft's mass is a liquid. Computational fluid dynamics simulations can be used to predict the dynamics of slosh, but these programs require extensive validation. Many experimental and numerical studies of water slosh have been conducted. However, slosh data for cryogenic liquids is lacking. Water and cryogenic liquid nitrogen are used in various ground-based tests with a spherical tank to characterize damping, slosh mode frequencies, and slosh forces. A single ring baffle is installed in the tank for some of the tests. Analytical models for slosh modes, slosh forces, and baffle damping are constructed based on prior work. Select experiments are simulated using a commercial CFD software, and the numerical results are compared to the analytical and experimental results for the purposes of validation and methodology-improvement.

  7. Equation of state of ammonia-water liquid - Derivation and planetological applications

    NASA Technical Reports Server (NTRS)

    Croft, S. K.; Lunine, J. I.; Kargel, J.

    1988-01-01

    The present least-squares fit calculation of the equation of state for ammonia-water liquid has yielded results for the zero-100 wt pct NH3, 170-300 K temperature, and zero-10 kb pressure parameter ranges. In conjunction with solid density and thermodynamic measurements, the present calculated and measured liquid densities are used to yield estimates of density and thermal expansion at 1 bar for the solid phases of ammonia's monohydrate, dihydrate, and hemihydrate between absolute zero and their respective melting points. Attention is given to the implications for icy satellite morphologic and tectonic forms of peritectic ammonia-water liquid that is neutrally buoyant relative to the corresponding solid phases.

  8. Communication: The Effect of Dispersion Corrections on the Melting Temperature of Liquid Water

    SciTech Connect

    Yoo, Soohaeng; Xantheas, Sotiris S.

    2011-03-28

    We report the results of the melting temperature (Tm) of liquid water for the Becke-Lee- Yang-Parr (BLYP) density functional including Dispersion corrections (BLYP-D) and the TTM3-F ab-initio based classical potential via constant pressure and constant enthalpy (NPH) ensemble molecular dynamics simulations of an ice Ih-liquid coexisting system. The inclusion of dispersion corrections to BLYP lowers the melting temperature of liquid water to Tm=360 K, which is a large improvement over the value of Tm > 400 K obtained with the original BLYP functional. The ab-initio based flexible, polarizable Thole-type model (TTM3-F) produces Tm=248 K from classical molecular dynamics simulations.

  9. Determination of pentachlorophenol in water and aquifer sediments by high-performance liquid chromatography

    USGS Publications Warehouse

    Goerlitz, D.F.

    1981-01-01

    Methods for the determination of pentachlorophenol (PCP) in water and aquifer sediments are presented. Reverse-phase high-performance liquid chromotography employing ion suppression and gradient elution is used. PCP can be determined directly in water at a lower limit of detection Of 0.2 micrograms per liter. For extracts of sediment, PCP can be determined to a lower limit of 1.0 micrograms per kilogram.

  10. What Determines the Ice Polymorph in Clouds?

    PubMed

    Hudait, Arpa; Molinero, Valeria

    2016-07-20

    Ice crystals in the atmosphere nucleate from supercooled liquid water and grow by vapor uptake. The structure of the ice polymorph grown has strong impact on the morphology and light scattering of the ice crystals, modulates the amount of water vapor in ice clouds, and can impact the molecular uptake and reactivity of atmospheric aerosols. Experiments and molecular simulations indicate that ice nucleated and grown from deeply supercooled liquid water is metastable stacking disordered ice. The ice polymorph grown from vapor has not yet been determined. Here we use large-scale molecular simulations to determine the structure of ice that grows as a result of uptake of water vapor in the temperature range relevant to cirrus and mixed-phase clouds, elucidate the molecular mechanism of the formation of ice at the vapor interface, and compute the free energy difference between cubic and hexagonal ice interfaces with vapor. We find that vapor deposition results in growth of stacking disordered ice only under conditions of extreme supersaturation, for which a nonequilibrium liquid layer completely wets the surface of ice. Such extreme conditions have been used to produce stacking disordered frost ice in experiments and may be plausible in the summer polar mesosphere. Growth of ice from vapor at moderate supersaturations in the temperature range relevant to cirrus and mixed-phase clouds, from 200 to 260 K, produces exclusively the stable hexagonal ice polymorph. Cubic ice is disfavored with respect to hexagonal ice not only by a small penalty in the bulk free energy (3.6 ± 1.5 J mol(-1) at 260 K) but also by a large free energy penalty at the ice-vapor interface (89.7 ± 12.8 J mol(-1) at 260 K). The latter originates in higher vibrational entropy of the hexagonal-terminated ice-vapor interface. We predict that the free energy penalty against the cubic ice interface should decrease strongly with temperature, resulting in some degree of stacking disorder in ice grown from

  11. Ion-water wires in imidazolium-based ionic liquid/water solutions induce unique trends in density.

    PubMed

    Ghoshdastidar, Debostuti; Senapati, Sanjib

    2016-03-28

    Ionic liquid/water binary mixtures are rapidly gaining popularity as solvents for dissolution of cellulose, nucleobases, and other poorly water-soluble biomolecules. Hence, several studies have focused on measuring the thermophysical properties of these versatile mixtures. Among these, 1-ethyl-3-methylimidazolium ([emim]) cation-based ILs containing different anions exhibit unique density behaviours upon addition of water. While [emim][acetate]/water binary mixtures display an unusual rise in density with the addition of low-to-moderate amounts of water, those containing the [trifluoroacetate] ([Tfa]) anion display a sluggish decrease in density. The density of [emim][tetrafluoroborate] ([emim][BF4])/water mixtures, on the other hand, declines rapidly in close accordance with the experimental reports. Here, we unravel the structural basis underlying this unique density behavior of [emim]-based IL/water mixtures using all-atom molecular dynamics (MD) simulations. The results revealed that the distinct nature of anion-water hydrogen bonded networks in the three systems was a key in modulating the observed unique density behaviour. Vast expanses of uninterrupted anion-water-anion H-bonded stretches, denoted here as anion-water wires, induced significant structuring in [emim][Ac]/water mixtures that resulted in the density rise. Conversely, the presence of intermittent large water clusters disintegrated the anion-water wires in [emim][Tfa]/water and [emim][BF4]/water mixtures to cause a monotonic density decrease. The differential nanostructuring affected the dynamics of the solutions proportionately, with the H-bond making and breaking dynamics found to be greatly retarded in [emim][Ac]/water mixtures, while it exhibited a faster relaxation in the other two binary solutions. PMID:26911708

  12. The molecular structure of the interface between water and a hydrophobic substrate is liquid-vapor like

    NASA Astrophysics Data System (ADS)

    Willard, Adam P.; Chandler, David

    2014-11-01

    With molecular simulation for water and a tunable hydrophobic substrate, we apply the instantaneous interface construction [A. P. Willard and D. Chandler, "Instantaneous liquid interfaces," J. Phys. Chem. B 114, 1954-1958 (2010)] to examine the similarity between a water-vapor interface and a water-hydrophobic surface interface. We show that attractive interactions between a hydrophobic surface and water affect capillary wave fluctuations of the instantaneous liquid interface, but these attractive interactions have essentially no effect on the intrinsic interface. The intrinsic interface refers to molecular structure in terms of distances from the instantaneous interface. Further, the intrinsic interface of liquid water and a hydrophobic substrate differs little from that of water and its vapor. The same is not true, we show, for an interface between water and a hydrophilic substrate. In that case, strong directional substrate-water interactions disrupt the liquid-vapor-like interfacial hydrogen bonding network.

  13. Simulations of the effects of water vapor, cloud liquid water, and ice on AMSU moisture channel brightness temperatures

    NASA Technical Reports Server (NTRS)

    Muller, Bradley M.; Fuelberg, Henry E.; Xiang, Xuwu

    1994-01-01

    Radiative transfer simulations are performed to determine how water vapor and nonprecipitating cloud liquid water and ice particles within typical midlatitude atmospheres affect brightness temperatures T(sub B)'s of moisture sounding channels used in the Advanced Microwave Sounding Unit (AMSU) and AMSU-like instruments. The purpose is to promote a general understanding of passive top-of-atmosphere T(sub B)'s for window frequencies at 23.8, 89.0, and 157.0 GHz, and water vapor frequencies at 176.31, 180.31, and 182.31 GHz by documenting specific examples. This is accomplished through detailed analyses of T(sub B)'s for idealized atmospheres, mostly representing temperate conditions over land. Cloud effects are considered in terms of five basic properties: droplet size distribution, phase, liquid or ice water content, altitude, and thickness. Effects on T(sub B) of changing surface emissivity also are addressed. The brightness temperature contribution functions are presented as an aid to physically interpreting AMSU T(sub B)'s. Both liquid and ice clouds impact the T(sub B)'s in a variety of ways. The T(sub B)'s at 23.8 and 89 GHz are more strongly affected by altostratus liquid clouds than by cirrus clouds for equivalent water paths. In contrast, channels near 157 and 183 GHz are more strongly affected by ice clouds. Higher clouds have a greater impact on 157- and 183-GHz T(sub B)'s than do lower clouds. Clouds depress T(sub B)'s of the higher-frequency channels by suppressing, but not necessarily obscuring, radiance contributions from below. Thus, T(sub B)'s are less closely associated with cloud-top temperatures than are IR radiometric temperatures. Water vapor alone accounts for up to 89% of the total attenuation by a midtropospheric liquid cloud for channels near 183 GHz. The Rayleigh approximation is found to be adequate for typical droplet size distributions; however, Mie scattering effects from liquid droplets become important for droplet size distribution

  14. Solute rotational dynamics at the water liquid/vapor interface

    NASA Astrophysics Data System (ADS)

    Benjamin, Ilan

    2007-11-01

    The rotational dynamics of a number of diatomic molecules adsorbed at different locations at the interface between water and its own vapors are studied using classical molecular dynamics computer simulations. Both equilibrium orientational and energy correlations and nonequilibrium orientational and energy relaxation correlations are calculated. By varying the dipole moment of the molecule and its location, and by comparing the results with those in bulk water, the effects of dielectric and mechanical frictions on reorientation dynamics and on rotational energy relaxation can be studied. It is shown that for nonpolar and weekly polar solutes, the equilibrium orientational relaxation is much slower in the bulk than at the interface. As the solute becomes more polar, the rotation slows down and the surface and bulk dynamics become similar. The energy relaxation (both equilibrium and nonequilibrium) has the opposite trend with the solute dipole (larger dipoles relax faster), but here again the bulk and surface results converge as the solute dipole is increased. It is shown that these behaviors correlate with the peak value of the solvent-solute radial distribution function, which demonstrates the importance of the first hydration shell structure in determining the rotational dynamics and dependence of these dynamics on the solute dipole and location.

  15. New Mexico cloud super cooled liquid water survey final report 2009.

    SciTech Connect

    Beavis, Nick; Roskovensky, John K.; Ivey, Mark D.

    2010-02-01

    Los Alamos and Sandia National Laboratories are partners in an effort to survey the super-cooled liquid water in clouds over the state of New Mexico in a project sponsored by the New Mexico Small Business Assistance Program. This report summarizes the scientific work performed at Sandia National Laboratories during the 2009. In this second year of the project a practical methodology for estimating cloud super-cooled liquid water was created. This was accomplished through the analysis of certain MODIS sensor satellite derived cloud products and vetted parameterizations techniques. A software code was developed to analyze multiple cases automatically. The eighty-one storm events identified in the previous year effort from 2006-2007 were again the focus. Six derived MODIS products were obtained first through careful MODIS image evaluation. Both cloud and clear-sky properties from this dataset were determined over New Mexico. Sensitivity studies were performed that identified the parameters which most influenced the estimation of cloud super-cooled liquid water. Limited validation was undertaken to ensure the soundness of the cloud super-cooled estimates. Finally, a path forward was formulized to insure the successful completion of the initial scientific goals which include analyzing different of annual datasets, validation of the developed algorithm, and the creation of a user-friendly and interactive tool for estimating cloud super-cooled liquid water.

  16. Dataset used to improve liquid water absorption models in the microwave

    SciTech Connect

    Turner, David

    2015-12-14

    Two datasets, one a compilation of laboratory data and one a compilation from three field sites, are provided here. These datasets provide measurements of the real and imaginary refractive indices and absorption as a function of cloud temperature. These datasets were used in the development of the new liquid water absorption model that was published in Turner et al. 2015.

  17. IMPACT OF ORGANIC COMPOUNDS ON THE CONCENTRATIONS OF LIQUID WATER IN AMBIENT PM2.5

    EPA Science Inventory

    A field study was undertaken during the summer of 2000 to assess the impact of the presence of organic compounds on the liquid water concentrations of PM2.5 samples. The selected site, located in Research Triangle Park, North Carolina, was in a semi-rural environment with expe...

  18. Observed and simulated temperature dependence of the liquid water path of low clouds

    SciTech Connect

    Del Genio, A.D.; Wolf, A.B.

    1996-04-01

    Data being acquired at the Atmospheric Radiation Measurement (ARM) Southern great Plains (SGP) Cloud and Radiation Testbed (CART) site can be used to examine the factors determining the temperature dependence of cloud optical thickness. We focus on cloud liquid water and physical thickness variations which can be derived from existing ARM measurements.

  19. GENERIC, COMPONENT FAILURE DATA BASE FOR LIGHT WATER AND LIQUID SODIUM REACTOR PRAs

    SciTech Connect

    S. A. Eide; S. V. Chmielewski; T. D. Swantz

    1990-02-01

    A comprehensive generic component failure data base has been developed for light water and liquid sodium reactor probabilistic risk assessments (PRAs) . The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and the Centralized Reliability Data Organization (CREDO) data bases were used to generate component failure rates . Using this approach, most of the failure rates are based on actual plant data rather than existing estimates .

  20. A hydrological analysis of terrestrial and Martian gullies: Implications for liquid water on Mars

    NASA Astrophysics Data System (ADS)

    Hobbs, S. W.; Paull, D. J.; Clarke, J. D. A.

    2014-12-01

    Understanding the role and amounts of liquid water involved in Martian gully formation is critical in studies of the Martian hydrosphere and climate. We performed hydrological analyses using the Manning and Darcy-Weisbach equations in order to infer flow velocities and discharge rates from channels at two gully sites in Noachis Terra, Mars. The results of these analyses were compared with analogous hillside gullies in Australia. We found the velocities and discharge rates for the terrestrial gullies to be comparable to velocities and discharge rates of some small Martian gully channels. In contrast, velocity and discharge in some larger Martian gullies were almost an order of magnitude higher, equating with catastrophic flows on Earth. We postulate that the larger gully channels were more likely formed by a number of smaller flows in a similar manner observed in some terrestrial gullies, a scenario that does not require vast amounts of liquid water to be stable under Martian conditions. In addition, we found that post-fluvial channel widening may have acted on the Martian gullies, probably by dry mass wasting, leading to larger channels than were originally carved by liquid water. Future hydrological analyses of Martian gullies will lead to a greater understanding of the relative importance of dry mass wasting compared to liquid water erosion.

  1. Parallel gastric emptying of nonhydrolyzable fat and water after a solid-liquid meal in humans

    SciTech Connect

    Cortot, A.; Phillips, S.F.; Malagelada, J.R.

    1982-05-01

    Our aim was to examine the control of gastric emptying of the oil phase of a mixed solid and liquid meal. Previous studies had shown that liquid dietary fats normally leave the stomach at a slower rate than does water. We wished to determine whether the slower emptying of fats was due to the physical characteristics of food (lower density and greater viscosity than water), to retardation by duodenal feedback mechanisms, or whether both factors contributed. Thus, we quantified the emptying rates of water and sucrose polyester (a nonabsorbable analog of dietary fat) ingested by healthy volunteers as a mixed solid and liquid meal. Gastric emptying was quantified by an intubation-perfusion method incorporating an occlusive jejunal balloon to facilitate recovery. Four phase-specific, nonabsorbable markers were used. (14C(Sucrose octaoleate and polyethylene glycol were incorporated in the meal and traced the lipid and water phases, respectively; (3H)glycerol triether and phenolsulfonphthalein were used as duodenal recovery markers. Sucrose polyester (substituting for dietary fat) was emptied very rapidly, and at about the same rate as was water, in contrast to natural fat, which empties very slowly. Emptying of water was rapid and comparable to that observed after mixed meals containing natural fat. These results imply that gastric emptying of the oil phase is controlled by receptors sensitive to the hydrolytic products of fat digestion and that the slow emptying of dietary fat is not simply due to its lower density.

  2. Optical Kerr effect of liquid and supercooled water: The experimental and data analysis perspective

    NASA Astrophysics Data System (ADS)

    Taschin, A.; Bartolini, P.; Eramo, R.; Righini, R.; Torre, R.

    2014-08-01

    The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful experimental tool enabling accurate investigations of the dynamic phenomena in molecular liquids. We introduced innovative experimental and fitting procedures, that enable a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of liquid water. We report OKE data on water measuring intermolecular vibrations and the structural relaxation processes in an extended temperature range, inclusive of the supercooled states. The unpreceded data quality makes possible a solid comparison with few theoretical models: the multi-mode Brownian oscillator model, the Kubo's discrete random jump model, and the schematic mode-coupling model. All these models produce reasonable good fits of the OKE data of stable liquid water, i.e., over the freezing point. The features of water dynamics in the OKE data becomes unambiguous only at lower temperatures, i.e., for water in the metastable supercooled phase. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if its intrinsic hydrodynamic approach does not give a direct access to the molecular information.

  3. Optical Kerr effect of liquid and supercooled water: the experimental and data analysis perspective.

    PubMed

    Taschin, A; Bartolini, P; Eramo, R; Righini, R; Torre, R

    2014-08-28

    The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful experimental tool enabling accurate investigations of the dynamic phenomena in molecular liquids. We introduced innovative experimental and fitting procedures, that enable a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of liquid water. We report OKE data on water measuring intermolecular vibrations and the structural relaxation processes in an extended temperature range, inclusive of the supercooled states. The unpreceded data quality makes possible a solid comparison with few theoretical models: the multi-mode Brownian oscillator model, the Kubo's discrete random jump model, and the schematic mode-coupling model. All these models produce reasonable good fits of the OKE data of stable liquid water, i.e., over the freezing point. The features of water dynamics in the OKE data becomes unambiguous only at lower temperatures, i.e., for water in the metastable supercooled phase. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if its intrinsic hydrodynamic approach does not give a direct access to the molecular information. PMID:25173021

  4. Initial evaluation of profiles of temperature, water vapor, and cloud liquid water from a new microwave profiling radiometer.

    SciTech Connect

    Liljegren, J. C.; Lesht, B. M.; Clothiaux, E. E.; Kato, S.

    2000-11-01

    To measure the vertical profiles of temperature and water vapor that are essential for modeling atmospheric processes, the Atmospheric Radiation Measurement (ARM) Program of the U. S. Department of Energy launches approximately 2600 radiosondes each year from its Southern Great Plains (SGP) facilities in Oklahoma and Kansas, USA. The annual cost of this effort exceeds $500,000 in materials and labor. Despite the expense, these soundings have a coarse temporal resolution and reporting interval compared with model time steps. In contrast, the radiation measurements used for model evaluations have temporal resolutions and reporting intervals of a few minutes at most. Conversely, radiosondes have a much higher vertical spatial resolution than most models can use. Modelers generally reduce the vertical resolution of the soundings by averaging over the vertical layers of the model. Recently, Radiometries Corporation (Boulder, Colorado, USA) developed a 12-channel, ground-based microwave radiometer capable of providing continuous, real-time vertical profiles of temperature, water vapor, and limited-resolution cloud liquid water from the surface to 10 km in nearly all weather conditions. The microwave radiometer profiler (MWRP) offers a much finer temporal resolution and reporting interval (about 10 minutes) than the radiosonde but a coarser vertical resolution that may be more appropriate for models. Profiles of temperature, water vapor, and cloud liquid water are obtained at 47 levels: from 0 to 1 km above ground level at 100-m intervals and from 1 to 10 km at 250-m intervals. The profiles are derived from the measured brightness temperatures with neural network retrieval. In Figure 1, profiles of temperature, water vapor, and cloud liquid water for 10 May 2000 are presented as time-height plots. MWRP profiles coincident with the 11:31 UTC (05:31 local) and 23:47 UTC (17:47 local) soundings for 10 May are presented in Figures 2 and 3, respectively. These profiles

  5. Nanofluid of zinc oxide nanoparticles in ionic liquid for single drop liquid microextraction of fungicides in environmental waters prior to high performance liquid chromatographic analysis.

    PubMed

    Amde, Meseret; Tan, Zhi-Qiang; Liu, Rui; Liu, Jing-Fu

    2015-05-22

    Using a nanofluid obtained by dispersing ZnO nanoparticles (ZnO NPs) in 1-hexyl-3-methylimidazolium hexafluorophosphate, new single drop microextraction method was developed for simultaneous extraction of three fungicides (chlorothalonil, kresoxim-methyl and famoxadone) in water samples prior to their analysis by high performance liquid chromatography (HPLC-VWD). The parameters affecting the extraction efficiency such as amount of ZnO NPs in the nanofluid, solvent volume, extraction time, stirring rate, pH and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.13-0.19ng/mL, the precision of the method assessed with intra-day and inter-day relative standard deviations were <4.82% and <7.04%, respectively. The proposed method was successfully applied to determine the three fungicides in real water samples including lake water, river water, as well as effluent and influent of wastewater treatment plant, with recoveries in the range of 74.94-96.11% at 5ng/mL spiking level. Besides to being environmental friendly, the high enrichment factor and the data quality obtained with the proposed method demonstrated its potential for application in multi residue analysis of fungicides in actual water samples. PMID:25857539

  6. Interaction of a long alkyl chain protic ionic liquid and water

    NASA Astrophysics Data System (ADS)

    Bodo, Enrico; Mangialardo, Sara; Capitani, Francesco; Gontrani, Lorenzo; Leonelli, Francesca; Postorino, Paolo

    2014-05-01

    A combined experimental/theoretical approach has been used to investigate the role of water in modifying the microscopic interactions characterizing the optical response of 1-butyl-ammonium nitrate (BAN) water solutions. Raman spectra, dominated by the signal from the protic ionic liquid, were collected as a function of the water content, and the corresponding spatial organization of the ionic couples, as well as their local arrangement with water molecules, was studied exploiting classical molecular dynamics calculations. High quality spectroscopic data, combined with a careful analysis, revealed that water affects the vibrational spectrum BAN in solution: as the water concentration is increased, peaks assigned to stretching modes show a frequency hardening together with a shape narrowing, whereas the opposite behavior is observed for peaks assigned to bending modes. Calculation results clearly show a nanometric spatial organization of the ionic couples that is not destroyed on increasing the water content at least within an intermediate range. Our combined results show indeed that small water concentrations even increase the local order. Water molecules are located among ionic couples and are closer to the anion than the cation, as confirmed by the computation of the number of H-bonds which is greater for water-anion than for water-cation. The whole results set thus clarifies the microscopic scenario of the BAN-water interaction and underlines the main role of the extended hydrogen bond network among water molecules and nitrate anions.

  7. Polymerized ionic liquid diblock copolymers: impact of water/ion clustering on ion conductivity.

    PubMed

    Nykaza, Jacob R; Ye, Yuesheng; Nelson, Rachel L; Jackson, Aaron C; Beyer, Frederick L; Davis, Eric M; Page, Kirt; Sharick, Sharon; Winey, Karen I; Elabd, Yossef A

    2016-01-28

    Herein, we examine the synergistic impact of both ion clustering and block copolymer morphology on ion conductivity in two polymerized ionic liquid (PIL) diblock copolymers with similar chemistries but different side alkyl spacer chain lengths (ethyl versus undecyl). When saturated in liquid water, water/ion clusters were observed only in the PIL block copolymer with longer alkyl side chains (undecyl) as evidenced by both small-angle neutron scattering and intermediate-angle X-ray scattering, i.e., water/ion clusters form within the PIL microdomain under these conditions. The resulting bromide ion conductivity in the undecyl sample was higher than the ethyl sample (14.0 mS cm(-1)versus 6.1 mS cm(-1) at 50 °C in liquid water) even though both samples had the same block copolymer morphology (lamellar) and the undecyl sample had a lower ion exchange capacity (0.9 meq g(-1)versus 1.4 meq g(-1)). No water/ion clusters were observed in either sample under high humidity or dry conditions. The resulting ion conductivity in the undecyl sample with lamellar morphology was significantly higher in the liquid water saturated state compared to the high humidity state (14.0 mS cm(-1)versus 4.2 mS cm(-1)), whereas there was no difference in ion conductivity in the ethyl sample when comparing these two states. These results show that small chemical changes to ion-containing block copolymers can induce water/ion clusters within block copolymer microdomains and this can subsequently have a significant effect on ion transport. PMID:26575014

  8. Computational Study of ions binding to the liquid interface of water

    SciTech Connect

    Dang, Liem X. )

    2002-08-12

    We have performed extensive classical molecular dynamics simulations to examine the molecular transport mechanisms of the I-, Br-, Cl- and Na+ ions across the liquid/vapor interface of water. The potentials of mean force were calculated using the constrained mean force approach and polarizable potential models were used to describe the interactions among the species. The simulated potentials of mean force were found to be different, depending on the type of anion. The larger I- and Br- anions bind more strongly to the liquid/vapor interface of water than did the smaller Cl-ion. It is important to note here that most of the gas phase and solution phase properties of the Br- anion are quite similar to that of the Cl- ion. At the interface, however, the interactions of the Br- and Cl- anions with the water interface appeared to be significantly different. We found that the anions approach the interface more closely do than cations. We have also studied the transport mechanism of an I- across the water/dichloromethane interface. The computed potential of mean force showed no well-defined minimum as in the liquid/vapor case, but a stabilization free energy of about?1 kcal/mol near the interface with respect to the bulk liquid was observed. The I- anion carried a water molecule with it as it crossed the interface. This result is in agreement with a recent experimental study on a similar system. Our work differs from earlier contributions in that our potential models have taken many-body effects into account, and in some cases, these effects cannot be neglected. To the best of our knowledge, this work significantly advances our understanding of molecular processes at the liquid interfaces.

  9. Non-porous membrane-assisted liquid-liquid extraction of UV filter compounds from water samples.

    PubMed

    Rodil, Rosario; Schrader, Steffi; Moeder, Monika

    2009-06-12

    A method for the determination of nine UV filter compounds [benzophenone-3 (BP-3), isoamyl methoxycinnamate, 4-methylbenzylidene camphor, octocrylene (OC), butyl methoxydibenzoylmethane, ethylhexyl dimethyl p-aminobenzoate (OD-PABA), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate and homosalate] in water samples was developed and evaluated. The procedure includes non-porous membrane-assisted liquid-liquid extraction (MALLE) and LC-atmospheric pressure photoionization (APPI)-MS/MS. Membrane bags made of different polymeric materials were examined to enable a fast and simple extraction of the target analytes. Among the polymeric materials tested, low- and high-density polyethylene membranes proved to be well suited to adsorb the analytes from water samples. Finally, 2 cm length tailor-made membrane bags were prepared from low-density polyethylene in order to accommodate 100 microL of propanol. The fully optimised protocol provides recoveries from 76% to 101% and limits of detection (LOD) between 0.4 ng L(-1) (OD-PABA) and 16 ng L(-1) (EHMC). The interday repeatability of the whole protocol was below 18%. The effective separation of matrix molecules was proved by only marginal matrix influence during the APPI-MS analysis since no ion suppression effects were observed. During the extraction step, the influence of the matrix was only significant when non-treated wastewater was analysed. The analysis of lake water indicated the presence of seven UV filter compounds included in this study at concentrations between 40 ng L(-1) (BP-3) and 4381 ng L(-1) (OC). In non-treated wastewater several UV filters were also detected at concentration levels as high as 5322 ng L(-1) (OC). PMID:19419722

  10. Finite-size scaling investigation of the liquid-liquid critical point in ST2 water and its stability with respect to crystallization

    NASA Astrophysics Data System (ADS)

    Kesselring, T. A.; Lascaris, E.; Franzese, G.; Buldyrev, S. V.; Herrmann, H. J.; Stanley, H. E.

    2013-06-01

    The liquid-liquid critical point scenario of water hypothesizes the existence of two metastable liquid phases—low-density liquid (LDL) and high-density liquid (HDL)—deep within the supercooled region. The hypothesis originates from computer simulations of the ST2 water model, but the stability of the LDL phase with respect to the crystal is still being debated. We simulate supercooled ST2 water at constant pressure, constant temperature, and constant number of molecules N for N ⩽ 729 and times up to 1 μs. We observe clear differences between the two liquids, both structural and dynamical. Using several methods, including finite-size scaling, we confirm the presence of a liquid-liquid phase transition ending in a critical point. We find that the LDL is stable with respect to the crystal in 98% of our runs (we perform 372 runs for LDL or LDL-like states), and in 100% of our runs for the two largest system sizes (N = 512 and 729, for which we perform 136 runs for LDL or LDL-like states). In all these runs, tiny crystallites grow and then melt within 1 μs. Only for N ⩽ 343 we observe six events (over 236 runs for LDL or LDL-like states) of spontaneous crystallization after crystallites reach an estimated critical size of about 70 ± 10 molecules.

  11. PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids

    NASA Astrophysics Data System (ADS)

    Chen, Sow-Hsin; Baglioni, Piero

    2012-02-01

    This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the

  12. Ionic liquid-based zinc oxide nanofluid for vortex assisted liquid liquid microextraction of inorganic mercury in environmental waters prior to cold vapor atomic fluorescence spectroscopic detection.

    PubMed

    Amde, Meseret; Liu, Jing-Fu; Tan, Zhi-Qiang; Bekana, Deribachew

    2016-03-01

    Zinc oxide nanofluid (ZnO-NF) based vortex assisted liquid liquid microextraction (ZnO-NF VA-LLME) was developed and employed in extraction of inorganic mercury (Hg(2+)) in environmental water samples, followed by cold vapor atomic fluorescence spectrometry (CV-AFS). Unlike other dispersive liquid liquid microextraction techniques, ZnO-NF VA-LLME is free of volatile organic solvents and dispersive solvent consumption. Analytical signals were obtained without back-extraction from the ZnO-NF phase prior to CV-AFS determination. Some essential parameters of the ZnO-NF VA-LLME and cold vapor generation such as composition and volume of the nanofluid, vortexing time, pH of the sample solution, amount of the chelating agent, ionic strength and matrix interferences have been studied. Under optimal conditions, efficient extraction of 1ng/mL of Hg(2+) in 10mL of sample solution was achieved using 50μL of ZnO-NF. The enrichment factor before dilution, detection limits and limits of quantification of the method were about 190, 0.019 and 0.064ng/mL, respectively. The intra and inter days relative standard deviations (n=8) were found to be 4.6% and 7.8%, respectively, at 1ng/mL spiking level. The accuracy of the current method was also evaluated by the analysis of certified reference materials, and the measured Hg(2+) concentration of GBW08603 (9.6ng/mL) and GBW(E)080392 (8.9ng/mL) agreed well with their certified value (10ng/mL). The method was applied to the analysis of Hg(2+) in effluent, influent, lake and river water samples, with recoveries in the range of 79.8-92.8% and 83.6-106.1% at 1ng/mL and 5ng/mL spiking levels, respectively. Overall, ZnO-NF VA-LLME is fast, simple, cost-effective and environmentally friendly and it can be employed for efficient enrichment of the analyte from various water samples. PMID:26717850

  13. Liquid Water Cloud Properties During the Polarimeter Definition Experiment (PODEX)

    NASA Technical Reports Server (NTRS)

    Alexandrov, Mikhail D.; Cairns, Brian; Wasilewski, Andrzei P.; Ackerman, Andrew S.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Platnick, Steven; Arnold, George; Van Diedenhoven, Bastiaan; Chowdhary, Jacek; Ottaviani, Matteo; Knobelspiesse, Kirk D.

    2015-01-01

    We present retrievals of water cloud properties from the measurements made by the Research Scanning Polarimeter (RSP) during the Polarimeter Definition Experiment (PODEX) held between January 14 and February 6, 2013. The RSP was onboard the high-altitude NASA ER-2 aircraft based at NASA Dryden Aircraft Operation Facility in Palmdale, California. The retrieved cloud characteristics include cloud optical thickness, effective radius and variance of cloud droplet size distribution derived using a parameter-fitting technique, as well as the complete droplet size distribution function obtained by means of Rainbow Fourier Transform. Multi-modal size distributions are decomposed into several modes and the respective effective radii and variances are computed. The methodology used to produce the retrieval dataset is illustrated on the examples of a marine stratocumulus deck off California coast and stratus/fog over California's Central Valley. In the latter case the observed bimodal droplet size distributions were attributed to two-layer cloud structure. All retrieval data are available online from NASA GISS website.

  14. Effect of water on the carbon dioxide absorption by 1-alkyl-3-methylimidazolium acetate ionic liquids.

    PubMed

    Stevanovic, Stéphane; Podgoršek, Ajda; Pádua, Agilio A H; Costa Gomes, Margarida F

    2012-12-13

    The absorption of carbon dioxide by the pure ionic liquids 1-ethyl-3-methylimidazolium acetate ([C(1)C(2)Im][OAc]) and 1-butyl-3-methylimidazolium acetate ([C(1)C(4)Im][OAc]) was studied experimentally from 303 to 343 K. As expected, the mole fraction of absorbed carbon dioxide is high (0.16 at 303 K and 5.5 kPa and 0.19 at 303 and 9.6 KPa for [C(1)C(2)Im][OAc] and [C(1)C(4)Im][OAc], respectively), does not obey Henry's law, and is compatible with the chemisorption of the gas by the liquid. Evidence of a chemical reaction between the gas and the liquid was found both by NMR and by molecular simulation. In the presence of water, the properties of the liquid absorber significantly change, especially the viscosity that decreases by as much as 25% (to 78 mPa s) and 30% (to 262 mPa s) in the presence of 0.2 mol fraction of water for [C(1)C(2)Im][OAc] and [C(1)C(2)Im][OAc] at 303 K, respectively. The absorption of carbon dioxide decreases when the water concentration increases: a decrease of 83% in CO(2) absorption is found for [C(1)C(4)Im][OAc] with 0.6 mol fraction of water at 303 K. It is proved in this work, by combining experimental data with molecular simulation, that the presence of water not only renders the chemical reaction between the gas and the ionic liquid less favorable but also lowers the (physical) solubility of the gas as it competes by the same solvation sites of the ionic liquid. The lowering of the viscosity of the liquid absorbent largely compensates these apparent drawbacks and the mixtures of [C(1)C(2)Im][OAc] and [C(1)C(2)Im][OAc] with water seem promising to be used for carbon dioxide capture. PMID:23145571

  15. Direct Observation of Self-Organized Water-Containing Structures in the Liquid Phase and Their Influence on 5-(Hydroxymethyl)furfural Formation in Ionic Liquids.

    PubMed

    Kashin, Alexey S; Galkin, Konstantin I; Khokhlova, Elena A; Ananikov, Valentine P

    2016-02-01

    Water-containing organic solutions are widespread reaction media in organic synthesis and catalysis. This type of multicomponent liquid system has a number of unique properties because of the tendency for water to self-organize in mixtures with other liquids. The characterization of these water domains is a challenging task because of their soft and dynamic nature. In the present study, the morphology and dynamics of micrometer- and nanometer-scale water-containing compartments in ionic liquids were directly observed by electron microscopy. A variety of morphologies, including isolated droplets, dense structures, aggregates, and 2D meshworks, have been experimentally detected and studied. Using the developed method, the impact of water on the acid-catalyzed biomass conversion reaction was studied at the microscopic level. The process that produced nanostructured domains in solution led to better yields and higher selectivities compared with reactions involving the bulk system. PMID:26754786

  16. Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy

    SciTech Connect

    Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

    2010-05-01

    We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

  17. Ultrafast Electron and Ion Dynamics in Strong-Field-Ionized Liquid Water

    NASA Astrophysics Data System (ADS)

    Loh, Zhi-Heng; Li, Jialin; Nie, Zhaogang; Zheng, Yi Ying; Dong, Shuo; Low, Pei Jiang

    2016-05-01

    The ionization of liquid water functions as the principal trigger for a myriad of phenomena that are relevant to radiation chemistry and biology. The earliest events that follow the ionization of water, however, remain relatively unknown. Here, femtosecond coherence spectroscopy is combined with polarization anisotropy measurements to elucidate the ultrafast electron and ion dynamics in ionized water. The results show that strong-field ionization of liquid water produces an aligned p electron distribution. Furthermore oscillations observed in the polarization anisotropy are suggestive of valence electron motion in the highly reactive H2 O+ radical cation, whose lifetime with respect to proton transfer is found to be 196 +/- 5 fs. Coherent intermolecular motions that signal initial solvent reorganization and subsequent long-lived ballistic proton transport that involves the H3 O+ end-product are also detected in the time domain. These results offer new insight into the elementary dynamics of ionized liquid water. This work is supported by the Ministry of Education (MOE2014-T2-2-052), A*Star (122-PSF-0011), and the Nanyang Assistant Professorship.

  18. Liquid water transport characteristics of porous diffusion media in polymer electrolyte membrane fuel cells: A review

    NASA Astrophysics Data System (ADS)

    Liu, Xunliang; Peng, Fangyuan; Lou, Guofeng; Wen, Zhi

    2015-12-01

    Fundamental understanding of liquid water transport in gas diffusion media (GDM) is important to improve the material and structure design of polymer electrolyte membrane (PEM) fuel cells. Continuum methods of two-phase flow modeling facilitate to give more details of relevant information. The proper empirical correlations of liquid water transport properties, such as capillary characteristics, water relative permeability and effective contact angle, are crucial to two phase flow modeling and cell performance prediction. In this work, researches on these properties in the last decade are reviewed. Various efforts have been devoted to determine the water transport properties for GDMs. However, most of the experimental studies are ex-situ measurements. In-situ measurements for GDMs and extending techniques available to study the catalyst layer and the microporous layer will be further challenges. Using the Leverett-Udell correlation is not recommended for quantitative modeling. The reliable Leverett-type correlation for GDMs, with the inclusion of the cosine of effective contact angle, is desirable but hard to be established for modeling two-phase flow in GDMs. A comprehensive data set of liquid water transport properties is needed for various GDM materials under different PEM fuel cell operating conditions.

  19. Local Structure in Ab Initio Liquid Water: Signatures of Amorphous Phases

    NASA Astrophysics Data System (ADS)

    Santra, Biswajit; Distasio, Robert A., Jr.; Martelli, Fausto; Car, Roberto

    Within the framework of density functional theory, the inclusion of exact exchange and non-local van der Waals/dispersion interactions is crucial for predicting a microscopic structure of ambient liquid water that quantitatively agrees with experiment. In this work, we have used the local structure index (LSI) order parameter to analyze the local structure in such highly accurate ab initio liquid water. At ambient conditions, the LSI probability distribution, P(I), was unimodal with most water molecules characterized by more disordered high-density-like local environments. With thermal excitations removed, the resultant bimodal P(I) in the inherent potential energy surface (IPES) exhibited a 3:1 ratio between high- and low-density-like molecules, with the latter forming small connected clusters amid the predominant population. By considering the spatial correlations and hydrogen bond network topologies among water molecules with the same LSI identities, we demonstrate that the signatures of the experimentally observed low- and high-density amorphous phases of ice are present in the IPES of ambient liquid water This work was supported by the DOE: DE-SC0008626, DE-SC0005180.

  20. PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids

    NASA Astrophysics Data System (ADS)

    Chen, Sow-Hsin; Baglioni, Piero

    2012-02-01

    This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the

  1. Improved sensitivity gas chromatography-mass spectrometry determination of parabens in waters using ionic liquids.

    PubMed

    Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

    2016-01-01

    A new procedure for the introduction of ionic liquid samples in gas chromatography (GC) is proposed. This procedure, based on microvial insert thermal desorption, allows the direct analysis of the compounds preconcentrated by ionic liquid based liquid-liquid microextraction (IL-LLME) using the combination of a thermal desorption unit (TDU) and a programmed temperature vaporization injector (PTV). Two different IL-LLME methodologies, one based on the formation of a microdroplet emulsion by dispersive liquid-liquid microextraction (DLLME) and other through ultrasound-assisted emulsification microextraction (USAEME) were studied and evaluated. IL-DLLME proved advantageous and consequently, it was adopted for preconcentration purposes. This easy to apply approach was used for the determination of five parabens (methyl-, ethyl-, propyl-, butyl- and isobutyl paraben) in swimming pool waters, after in situ acetylation. The optimized conditions of TDU/PTV allowed the analytes contained in 20 µL of the enriched IL to be transferred to the capillary column. Quantification of the samples was carried out against aqueous standards, and quantification limits of between 4.3 and 8.1 ng L(-1) were obtained, depending on the compound. Concentrations of between 9 and 47 ng L(-1) for some analytes were obtained in the analysis of ten samples. PMID:26695305

  2. Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.

    PubMed

    Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario

    2014-12-01

    The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions. PMID:25326892

  3. Slow dielectric response of Debye-type in water and other hydrogen bonded liquids

    NASA Astrophysics Data System (ADS)

    Jansson, Helén; Bergman, Rikard; Swenson, Jan

    2010-05-01

    The slow dynamics of some hydrogen bonded glass-forming liquids has been investigated by broadband dielectric spectroscopy. We show that the polyalcohols glycerol, xylitol, and sorbitol, and mixtures of glycerol and water, and in fact, even pure water exhibit a process of Debye character at longer time-scales than the glass transition and viscosity related α-relaxation. Even if it is less pronounced, this process displays many similarities to the well-studied Debye-like process in monoalcohols. It can be observed in both the negative derivative of the real part of the permittivity or in the imaginary part of the permittivity, if the conductivity contribution is reduced. In the present study the conductivity contribution has been suppressed by use of a thin Teflon film placed between the sample and one of the electrodes. The new findings might have important implications for the structure and dynamics of hydrogen bonded liquids in general, and for water in particular.

  4. A supramolecular structure insight for conversion property of cellulose in hot compressed water: Polymorphs and hydrogen bonds changes.

    PubMed

    Wang, Yan; Lian, Jie; Wan, Jinquan; Ma, Yongwen; Zhang, Yingshi

    2015-11-20

    Waste paper samples with different cellulose supramolecular structure were treated in hot compressed water (HCW) at 375°C and 22.5MPa within 200s to evaluate the specific effect mechanism of cellulose supramolecular structure on the conversion of waste paper to reusable resource. Although the distribution of liquid products and the oligosaccharides were related to reaction time, depolymerization and decrystallization of the cellulose, the characteristics absorption peak of cellulose from FTIR analysis and crystal structure of the cellulose detected in the residues with hydrolysis rate up 96.5% indicated crystal structure was the dominant factor that affect conversion behavior of waste paper. The conversion of cellulose Iβ to cellulose Iα or cellulose I(α+β) in HCW demonstrated that the recrystallization occurred during the decrystallization of cellulose through the rearrangement of hydrogen bonds. PMID:26344260

  5. Impact-Induced Liquid-Water Environments on Mars

    NASA Astrophysics Data System (ADS)

    Daubar, I. J.; Kring, D. A.

    2001-11-01

    The origin and evolution of life on Earth were likely associated with hydrothermal systems (e.g., Corliss et al. 1980, Baross and Hoffman 1985, Holm and Andersson 1995, Shock 1996). Although research has been concentrated on volcanic hydrothermal systems on Earth (e.g., Norton 1984, Farmer 2000) and on Mars (e.g., Allen et al. 1982, Gulick and Baker 1989, Farmer 1996), we suggest that large impacts can, and did, drive similar systems. Impacts are a significant source of thermal energy: melt rock produced in impacts, and hot rock uplifted from depth both provide sources of heat to drive hydrothermal systems. On Mars, these heat sources could provide enough energy to melt an underlying layer of permafrost and perhaps even initiate long-lived crater lakes (Newsom et al. 1996, Cabrol et al. 1999). In terms of the production of heat and the habitable volume incorporated in hydrothermal systems, impacts might have been at least as important as volcanic systems early in planetary development. The oldest (Noachian) surfaces on Mars support this hypothesis: they show very little evidence of volcanism (Carr 1996) and are instead dominated by impact cratering processes. Kring and Cohen (2001, submitted) estimate that more than 6400 craters with diameters greater than 20 km were produced on Mars 3.9 Ga. We present estimates of the lifetimes of hydrothermal systems in Martian craters with sizes ranging from 20 km to 200 km in diameter. Lifetimes calculated assuming convective cooling are 105 years for 100-km craters and several 106 years for 180-km craters (Daubar and Kring 2001, cf. Thorsos et al. 2001). These results may be influenced by an insulating breccia layer, shock heating, and convection of water; these factors are currently being evaluated.

  6. Estimation of Interfacial Tension between Organic Liquid Mixtures and Water

    SciTech Connect

    Yoon, Hongkyu; Oostrom, Martinus; Werth, Charles J.

    2009-10-15

    Knowledge of IFT values for chemical mixtures helps guide the design and analysis of various processes, including NAPL remediation with surfactants or alcohol flushing, enhanced oil recovery, and chemical separation technologies, yet available literature values are sparse. A comprehensive comparison of thermodynamic and empirical models for estimating interfacial tension (IFT) of organic chemical mixtures with water is conducted, mainly focusing on chlorinated organic compounds for 14 ternary, three quaternary, and one quinary systems. Emphasis is placed on novel results for systems with three and four organic chemical compounds, and for systems with composite organic compounds like lard oil and mineral oil. Seven models are evaluated: the ideal and nonideal monolayer models (MLID and MLNID), the ideal and nonideal mutual solubility models (MSID and MSNID), an empirical model for ternary systems (EM), a linear mixing model based on mole fractions (LMMM), and a newly developed linear mixing model based on volume fractions of organic mixtures (LMMV) for higher order systems. The two ideal models (MLID and MSID) fit ternary systems of chlorinated organic compounds without surface active compounds relatively well. However, both ideal models did not perform well for the mixtures containing a surface active compound. However, for these systems, both the MLNID and MSNID models matched the IFT data well. It is shown that the MLNID model with a surface coverage value (0.00341 mmol/m2) obtained in this study can practically be used for chlorinated organic compounds. The LMMM results in poorer estimates of the IFT as the difference in IFT values of individual organic compounds in a mixture increases. The EM, with two fitting parameters, provided accurate results for all 14 ternary systems including composite organic compounds. The new LMMV method for quaternary and higher component systems was successfully tested. This study shows that the LMMV may be able to be used for

  7. Experimental determination of cavitation thresholds in liquid water and mercury

    SciTech Connect

    Taleyarkhan, R.P.; Gulec, K.; West, C.D.; Haines, J.

    1998-09-01

    It is well-known that fluids (like solids) will break apart or form voids when put under sufficient tension. The present study has been motivated by the need to evaluate the impact of fluid cavitation in spallation neutron source target systems, more specifically for the proposed 1-MW Spallation Neutron Source (SNS) project, which is being designed in collaboration between Oak Ridge National Laboratory (ORNL), Los Alamos National Laboratory, Lawrence Berkeley National Laboratory, Brookhaven National Laboratory, and Argonne National Laboratory. Indeed, results of SNS-specific simulations have indicated that the onset of cavitation could play a very significant role in reducing imposed stresses in structural components of the SNS. In general, the cavitation of fluids is target systems is important to consider for a variety of reasons. Its occurrence can have significant impact on heat transfer, pressure pulse generation, fluid jetting on to structures, surface erosion, stresses induced in enclosures, etc. Therefore, it is important to evaluate the threshold pressure under which the fluid in tension will undergo cavitation. Another major aspect concerns the possible onset of cavitation in an oscillating pressure field; i.e., one would need to know if fluids such as mercury and water will cavitate if the imposed tensile pressure in the fluid is of short duration. If indeed it takes sufficiently long for cavitation bubbles to nucleate, then it would be possible to disregard the complexities involved with addressing cavitation-related issues. This paper provides an overview of preliminary work done to date to derive information on cavitation onset in a relatively static and in a high-frequency environment.

  8. Gas-liquid chromatographic determination of 3-trifluoromethyl-4-nitrophenol in natural waters.

    PubMed

    Coburn, J A; Chau, A S

    1976-07-01

    A procedure for the analysis of 3-trifluoromethyl-4-nitrophenol (TFM) in natural waters is described. The lampricide is extracted from acidified water samples on the macroreticular resin XAD-7 and eluted from the column with ethyl ether. The ether extract is dried, concentrated, and partitioned with potassium carbonate. TFM is acetylated in the aqueous alkaline solution and the acetate derivative is extracted into benzene for analysis by electron capture gas-liquid chromatography. Recoveries of TFM from natural waters exceeded 90% and as little as 0.01 mug TFM can be quantitated in a 1 L sample. PMID:939751

  9. Interaction of monovalent ions with the water liquid-vapor interface - A molecular dynamics study

    NASA Technical Reports Server (NTRS)

    Wilson, Michael A.; Pohorille, Andrew

    1991-01-01

    Results of molecular dynamics calculations are presented for a series of ions at infinite dilution near the water liquid-vapor interface. The free energies of ion transfer from the bulk to the interface are discussed, as are the accompanying changes of water structure at the surface and ion mobilities as a function of their proximity to the interface. It is shown that simple dielectric models do not provide an accurate description of ions at the water surface. The results of the study should be useful in the development of better models incorporating the shape and molecular structure of the interface.

  10. Structural and dipolar fluctuations in liquid water: A Car-Parrinello molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Skarmoutsos, Ioannis; Masia, Marco; Guardia, Elvira

    2016-03-01

    A Car-Parrinello molecular dynamics simulation was performed to investigate the local tetrahedral order, molecular dipole fluctuations and their interrelation with hydrogen bonding in liquid water. Water molecules were classified in three types, exhibiting low, intermediate and high tetrahedral order. Transitions from low to high tetrahedrally ordered structures take place only through transitions to the intermediate state. The molecular dipole moments depend strongly on the tetrahedral order and hydrogen bonding. The average dipole moment of water molecules with a strong tetrahedral order around them comes in excellent agreement with previous estimations of the dipole moment of ice Ih molecules.

  11. The effects of dissolved halide anions on hydrogen bonding in liquid water.

    PubMed

    Smith, Jared D; Saykally, Richard J; Geissler, Phillip L

    2007-11-14

    It is widely believed that the addition of salts to water engenders structural changes in the hydrogen-bond network well beyond the adjacent shell of solvating molecules. Classification of many ions as "structure makers" and "structure breakers" has been based in part on corresponding changes in the vibrational spectra (Raman and IR). Here we show that changes in O-H vibrational spectra induced by the alkali halides in liquid water result instead from the actions of ions' electric fields on adjacent water molecules. Computer simulations that accurately reproduce our experimental measurements suggest that the statistics of hydrogen-bond strengths are only weakly modified beyond this first solvation shell. PMID:17958418

  12. Molecular dynamics simulations of the liquid/vapor interface of SPC/E water

    SciTech Connect

    Taylor, R.S.; Dang, L,X.; Garrett, B.C.

    1996-07-11

    Molecular dynamics computer simulations have been used to explore the structural and dynamical properties of water`s liquid/vapor interface using the simple extended point charge (SPC/E) model. Comparisons to the existing experimental and simulation data suggest that the SPC/E potential energy function provides a semiquantitative description of this interface. The orientation of H{sub 2}O molecules at the interface is found to be bimodal in nature. The self-diffusion constant of water is calculated to be larger at the surface than in the bulk. 46 refs., 10 figs., 1 tab.

  13. The Effect of Combinations of Food Insects for Continuous Rearing of the Wing Polymorphic Water Strider Limnogonus Fossarum fossarum (Hemiptera: Gerridae).

    PubMed

    Hirooka, Y; Hagizuka, C; Ohshima, I

    2016-01-01

    The water strider Limnogonus fossarum fossarum (F.) (Hemiptera: Gerridae) shows a macropterous, micropterous, and apterous polymorphism. Although a long photoperiod condition induces winged morphs, preliminary studies have revealed that crossing between winged morphs increased the proportion of macropterous individuals, suggesting that the genetic factors also affect wing-morph determination in this species. Assessing the genetic backgrounds of wing polymorphism requires constant and repeatable methods for rearing. This study attempts to establish a continuous rearing method for L. f. fossarum under constant diet conditions. Initially, we maintain the water striders with two Drosophila species as a food, but viability until adulthood is less than 20%. We then add the storage pest Plodia interpunctella (Hübner), which are readily reared in the laboratory, to the diets. As a result, nymphs fed on P. interpunctella (even only until the second instar) show significantly higher viability and shorter developmental period than nymphs fed on Drosophila alone. Moreover, feeding on D. melanogaster (Meigen) reared on cholesterol-enriched medium instead of a normal medium significantly increases viability in the next generation. This means that only the two food-insect species are enough for establishing a substantial number of individuals in segregating generations (F2 and backcross), limiting DNA and RNA contaminations from food insects with genome information. Thus, the present rearing method opens the way to elucidating the genetic backgrounds of the wing polymorphism in L. f. fossarum. PMID:27620554

  14. The Effect of Combinations of Food Insects for Continuous Rearing of the Wing Polymorphic Water Strider Limnogonus Fossarum fossarum (Hemiptera: Gerridae)

    PubMed Central

    Hirooka, Y.; Hagizuka, C.; Ohshima, I.

    2016-01-01

    The water strider Limnogonus fossarum fossarum (F.) (Hemiptera: Gerridae) shows a macropterous, micropterous, and apterous polymorphism. Although a long photoperiod condition induces winged morphs, preliminary studies have revealed that crossing between winged morphs increased the proportion of macropterous individuals, suggesting that the genetic factors also affect wing-morph determination in this species. Assessing the genetic backgrounds of wing polymorphism requires constant and repeatable methods for rearing. This study attempts to establish a continuous rearing method for L. f. fossarum under constant diet conditions. Initially, we maintain the water striders with two Drosophila species as a food, but viability until adulthood is less than 20%. We then add the storage pest Plodia interpunctella (Hübner), which are readily reared in the laboratory, to the diets. As a result, nymphs fed on P. interpunctella (even only until the second instar) show significantly higher viability and shorter developmental period than nymphs fed on Drosophila alone. Moreover, feeding on D. melanogaster (Meigen) reared on cholesterol-enriched medium instead of a normal medium significantly increases viability in the next generation. This means that only the two food-insect species are enough for establishing a substantial number of individuals in segregating generations (F2 and backcross), limiting DNA and RNA contaminations from food insects with genome information. Thus, the present rearing method opens the way to elucidating the genetic backgrounds of the wing polymorphism in L. f. fossarum. PMID:27620554

  15. An Environmental Chamber to Investigate Liquid Saline Water in the Martian Polar Region

    NASA Astrophysics Data System (ADS)

    Elliott, H. M.; Martinez, G. M.; Halleaux, D. G.; Braswell, S. F.; Renno, N. O.

    2012-04-01

    We present the design of an environmental chamber to simulate the diurnal and seasonal cycles of the Martian polar region. This chamber is being built to aid in the investigation of liquid saline water in Mars' Richardson Crater (72° S, 179° E) and the Mars Phoenix Lander site (68° N, 126° W). Our objective is to: (i) determine the environmental conditions at with brines, formed from perchlorate salts found by the Mars Phoenix Lander, are stable on the surface of Mars and (ii) determine the optical properties of liquid saline water flows hypothesized to exist in Mars' Richardson Crater. The environmental chamber system consists of a vacuum chamber with six internal thermal plates. The plates are arranged to form a cubic thermal cavity that can be cryogenically cooled by liquid nitrogen. Additional thermal control is attained through the use of resistive patch heaters, which are fixed on the thermal plates. The vacuum chamber inlet is connected to a carbon dioxide dry gas stream, which can be throttled to control the chamber's humidity. The vacuum chamber outlet passes through a chilled mirror hygrometer to measure the chamber humidity before the air exits the vacuum pump. Acknowledgements: This research is supported by a grant from the NASA Astrobiology Program: Exobiology and Evolutionary Biology. Award #09-EXOB09-0050. Keywords: Liquid Saline Water, Cryobrines, Richardson Crater, Mars Phoenix Lander

  16. Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

    SciTech Connect

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A.

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H{sub 2}O-NaCl and H{sub 2}O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  17. MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Datasets

    SciTech Connect

    KL Gaustad; DD Turner

    2007-09-30

    This report provides a short description of the Atmospheric Radiation Measurement (ARM) microwave radiometer (MWR) RETrievel (MWRRET) Value-Added Product (VAP) algorithm. This algorithm utilizes complimentary physical and statistical retrieval methods and applies brightness temperature offsets to reduce spurious liquid water path (LWP) bias in clear skies resulting in significantly improved precipitable water vapor (PWV) and LWP retrievals. We present a general overview of the technique, input parameters, output products, and describe data quality checks. A more complete discussion of the theory and results is given in Turner et al. (2007b).

  18. Ultrafast soft X-ray photoelectron spectroscopy at liquid water microjets.

    PubMed

    Faubel, M; Siefermann, K R; Liu, Y; Abel, B

    2012-01-17

    Since the pioneering work of Kai Siegbahn, electron spectroscopy for chemical analysis (ESCA) has been developed into an indispensable analytical technique for surface science. The value of this powerful method of photoelectron spectroscopy (PES, also termed photoemission spectroscopy) and Siegbahn's contributions were recognized in the 1981 Nobel Prize in Physics. The need for high vacuum, however, originally prohibited PES of volatile liquids, and only allowed for investigation of low-vapor-pressure molecules attached to a surface (or close to a surface) or liquid films of low volatility. Only with the invention of liquid beams of volatile liquids compatible with high-vacuum conditions was PES from liquid surfaces under vacuum made feasible. Because of the ubiquity of water interfaces in nature, the liquid water-vacuum interface became a most attractive research topic, particularly over the past 10 years. PES studies of these important aqueous interfaces remained significantly challenging because of the need to develop high-pressure PES methods. For decades, ESCA or PES (termed XPS, for X-ray photoelectron spectroscopy, in the case of soft X-ray photons) was restricted to conventional laboratory X-ray sources or beamlines in synchrotron facilities. This approach enabled frequency domain measurements, but with poor time resolution. Indirect access to time-resolved processes in the condensed phase was only achieved if line-widths could be analyzed or if processes could be related to a fast clock, that is, reference processes that are fast enough and are also well understood in the condensed phase. Just recently, the emergence of high harmonic light sources, providing short-wavelength radiation in ultrashort light pulses, added the dimension of time to the classical ESCA or XPS technique and opened the door to (soft) X-ray photoelectron spectroscopy with ultrahigh time resolution. The combination of high harmonic light sources (providing radiation with laserlike

  19. Ionic liquids as mobile phase additives for the high-performance liquid chromatographic analysis of fluoroquinolone antibiotics in water samples.

    PubMed

    Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Angel

    2008-12-01

    In this work, four ionic liquids differing in the length of the alkyl chain on the imidazolium cation and one ionic liquid containing tetraethylammonium, all with the same counterion, (i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm-BF(4)), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF(4)), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIm-BF(4)), 1-methyl-3-octylimidazolium tetrafluoroborate (MOIm-BF(4)), and tetraethylammonium tetrafluroborate (Et(4)N-BF(4))) were tested as mobile phase additives for HPLC separation of a group of seven basic fluoroquinolone (FQ) antibiotics for human and veterinary use (i.e. fleroxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, and difloxacin) using a conventional reversed-phase Nova-Pak C(18) column. Fluorescence detection was used. Among the ionic liquids selected, use of BMIm-BF(4) enabled effective separation of these compounds with relatively low analysis time (14 min). The best separation was achieved by isocratic elution at 1 mL min(-1) with 5 mmol L(-1) BMIm-BF(4) and 10 mmol L(-1) ammonium acetate at pH 3.0 with 13% (v/v) acetonitrile. Limits of detection (LODs) for fluorescence detection were in the range 0.5-11 microg L(-1). The method was tested by analyzing several water samples after the optimization of a suitable solid-phase extraction (SPE) procedure using Oasis HLB cartridges. Mean recovery values were above 84% for all analytes with LODs in the range 1-29 ng L(-1). PMID:18854988

  20. Formation of H-type liquid crystal dimer at air-water interface

    SciTech Connect

    Karthik, C. Gupta, Adbhut Joshi, Aditya Manjuladevi, V. Gupta, Raj Kumar; Varia, Mahesh C.; Kumar, Sandeep

    2014-04-24

    We have formed the Langmuir monolayer of H-shaped Azo linked liquid crystal dimer molecule at the air-water interface. Isocycles of the molecule showed hysteresis suggesting the ir-reversible nature of the monolayer formed. The thin film deposited on the silicon wafer was characterized using Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM). The images showed uniform domains of the dimer molecule. We propose that these molecules tend to take book shelf configuration in the liquid phase.

  1. Transient Numerical Modeling of the Combustion of Bi-Component Liquid Droplets: Methanol/Water Mixture

    NASA Technical Reports Server (NTRS)

    Marchese, A. J.; Dryer, F. L.

    1994-01-01

    This study shows that liquid mixtures of methanol and water are attractive candidates for microgravity droplet combustion experiments and associated numerical modeling. The gas phase chemistry for these droplet mixtures is conceptually simple, well understood and substantially validated. In addition, the thermodynamic and transport properties of the liquid mixture have also been well characterized. Furthermore, the results obtained in this study predict that the extinction of these droplets may be observable in ground-based drop to tower experiments. Such experiments will be conducted shortly followed by space-based experiments utilizing the NASA FSDC and DCE experiments.

  2. Attempt to determine the environmental 36Cl concentration in water by liquid scintillation counting

    NASA Astrophysics Data System (ADS)

    Florkowski, T.; Schuszler, Ch.

    1986-11-01

    A low-background liquid scintillation spectrometer (ALOKA SL-1) located in the IAEA Isotope Hydrology Laboratory in Vienna was used for 36Cl activity measurement in water samples. The procedure of sample preparation consists of synthesizing of silicon tetrachloride or sodium chloride followed by purification. In both cases the limiting factor in the analysis appeared to be the pure reproducibility of the sample preparation procedure. The conclusion from these experiments is that the liquid scintillation method could be feasible only for the identification of the "bomb chlorine" but is far from being suitable for the accurate determination of 36Cl in groundwater for dating purposes.

  3. Liquid Water Lakes on Mars Under Present-Day Conditions: Sustainability and Effects on the Subsurface

    NASA Astrophysics Data System (ADS)

    Goldspiel, Jules M.

    2015-11-01

    Decades of Mars exploration have produced ample evidence that aqueous environments once existed on the surface. Much evidence supports groundwater emergence as the source of liquid water on Mars [1-4]. However, cases have also been made for rainfall [5] and snow pack melts [6].Whatever the mechanism by which liquid water is emplaced on the surface of Mars, whether from groundwater seeps, atmospheric precipitation, or some combination of sources, this water would have collected in local topographic lows, and at least temporarily, would have created a local surface water system with dynamic thermal and hydrologic properties. Understanding the physical details of such aqueous systems is important for interpreting the past and present surface environments of Mars. It is also important for evaluating potential habitable zones on or near the surface.In conjunction with analysis of surface and core samples, valuable insight into likely past aqueous sites on Mars can be gained through modeling their formation and evolution. Toward that end, we built a 1D numerical model to follow the evolution of small bodies of liquid water on the surface of Mars. In the model, liquid water at different temperatures is supplied to the surface at different rates while the system is subjected to diurnally and seasonally varying environmental conditions. We recently simulated cases of cold (275 K) and warm (350 K) water collecting in a small depression on the floor of a mid southern latitude impact crater. When inflows create an initial pool > 3 m deep and infiltration can be neglected, we find that the interior of the pool can remain liquid over a full Mars year under the present cold and dry climate as an ice cover slowly thickens [7]. Here we present new results for the thermal and hydrologic evolution of surface water and the associated subsurface region for present-day conditions when infiltration of surface water into the subsurface is considered.[1] Pieri (1980) Science 210.[2] Carr

  4. Nimbus 7 SMMR Derived Seasonal Variations in the Water Vapor, Liquid Water and Surface Winds over the Global Oceans

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Short, D. A.

    1984-01-01

    Monthly mean distributions of water vapor and liquid water contained in a vertical column of the atmosphere and the surface wind speed were derived from Nimbus Scanning Multichannel Microwave Radiometer (SMMR) observations over the global oceans for the period November 1978 to November 1979. The remote sensing techniques used to estimate these parameters from SMMR are presented to reveal the limitations, accuracies, and applicability of the satellite-derived information for climate studies. On a time scale of the order of a month, the distribution of atmospheric water vapor over the oceans is controlled by the sea surface temperature and the large scale atmospheric circulation. The monthly mean distribution of liquid water content in the atmosphere over the oceans closely reflects the precipitation patterns associated with the convectively and baroclinically active regions. Together with the remotely sensed surface wind speed that is causing the sea surface stress, the data collected reveal the manner in which the ocean-atmosphere system is operating. Prominent differences in the water vapor patterns from one year to the next, or from month to month, are associated with anomalies in the wind and geopotential height fields. In association with such circulation anomalies the precipitation patterns deduced from the meteorological network over adjacent continents also reveal anomalous distributions.

  5. Linking Europa's plume activity to tides, tectonics, and liquid water

    NASA Astrophysics Data System (ADS)

    Rhoden, Alyssa Rose; Hurford, Terry A.; Roth, Lorenz; Retherford, Kurt

    2015-06-01

    Much of the geologic activity preserved on Europa's icy surface has been attributed to tidal deformation, mainly due to Europa's eccentric orbit. Although the surface is geologically young (30-80 Myr), there is little information as to whether tidally-driven surface processes are ongoing. However, a recent detection of water vapor near Europa's south pole suggests that it may be geologically active. Initial observations indicated that Europa's plume eruptions are time-variable and may be linked to its tidal cycle. Saturn's moon, Enceladus, which shares many similar traits with Europa, displays tidally-modulated plume eruptions, which bolstered this interpretation. However, additional observations of Europa at the same time in its orbit failed to yield a plume detection, casting doubt on the tidal control hypothesis. The purpose of this study is to analyze the timing of plume eruptions within the context of Europa's tidal cycle to determine whether such a link exists and examine the inferred similarities and differences between plume activity on Europa and Enceladus. To do this, we determine the locations and orientations of hypothetical tidally-driven fractures that best match the temporal variability of the plumes observed at Europa. Specifically, we identify model faults that are in tension at the time in Europa's orbit when a plume was detected and in compression at times when the plume was not detected. We find that tidal stress driven solely by eccentricity is incompatible with the observations unless additional mechanisms are controlling the eruption timing or restricting the longevity of the plumes. The addition of obliquity tides, and corresponding precession of the spin pole, can generate a number of model faults that are consistent with the pattern of plume detections. The locations and orientations of these hypothetical source fractures are robust across a broad range of precession rates and spin pole directions. Analysis of the stress variations across

  6. The effect of the partial pressure of water vapor on the surface tension of the liquid water-air interface.

    PubMed

    Pérez-Díaz, José L; Álvarez-Valenzuela, Marco A; García-Prada, Juan C

    2012-09-01

    Precise measurements of the surface tension of water in air vs. humidity at 5, 10, 15, and 20 °C are shown. For constant temperature, surface tension decreases linearly for increasing humidity in air. These experimental data are in good agreement with a simple model based on Newton's laws here proposed. It is assumed that evaporating molecules of water are ejected from liquid to gas with a mean normal component of the speed of "ejection" greater than zero. A high humidity in the air reduces the net flow of evaporating water molecules lowering the effective surface tension on the drop. Therefore, just steam in air acts as an effective surfactant for the water-air interface. It can partially substitute chemical surfactants helping to reduce their environmental impact. PMID:22717083

  7. Site-site direct correlation functions for three popular molecular models of liquid water

    NASA Astrophysics Data System (ADS)

    Zhao, Shuangliang; Liu, Yu; Liu, Honglai; Wu, Jianzhong

    2013-08-01

    Direct correlation functions (DCFs) play a pivotal role in the applications of classical density functional theory (DFT) to addressing the thermodynamic properties of inhomogeneous systems beyond the local-density or mean-field approximations. Whereas numerous studies have been dedicated to the radial distribution functions of liquid water - the most important solvent on earth, relatively little attention has been given to the site-site DCFs. The water DCFs are long-ranged and difficult to calculate directly by simulation, and the predictions from conventional liquid-state theories have been rarely calibrated. Here we report a computational procedure for accurate evaluation of the site-site DCFs of liquid water based on three popular molecular models (viz., SPC, SPC/E, and TIP3P). The numerical results provide a benchmark for calibration of conventional liquid-state theories and fresh insights into development of new DFT methods. We show that: (1) the long-range behavior of the site-site DCFs depends on both the molecular model and the thermodynamic condition; (2) the asymptotic limit of DCFs at large distance does not follow the mean-spherical approximation (MSA); (3) individual site-site DCFs are long ranged (˜40 nm) but a summation of all DCF pairs exhibits only short-range behavior (˜1 nm or a few water diameters); (4) the site-site bridge correlation functions behave as the DCFs, i.e., they are also long-ranged while the summation of all bridge correlation functions is short ranged. Our analytical and numerical analyses of the DCFs provide some simple strategies for possible improvement of the numerical performance of conventional liquid-state theories.

  8. A model of vapor-liquid equilibria for acid gas-alkanolamine-water systems

    SciTech Connect

    Austgen, D.M. Jr.

    1989-01-01

    A physico-chemical model was developed for representing liquid phase chemical equilibria and vapor-liquid (phase) equilibria of H{sub 2}SCO{sub 2}-alkanolamine-water systems. The equilibrium composition of the liquid phase is determined by minimization of the Gibbs free energy. Activity coefficients are represented with the Electrolyte-NRTL equation treating both long-range electrostatic interactions and short-range binary interactions between liquid phase species. Vapor phase fugacity coefficients are calculated using the Redlich-Kwong-Soave Equation of State. Adjustable parameters of the model, binary interaction parameters and carbamate stability constants, were fitted on published binary system alkanolamine-water and ternary system (H{sub 2}S-alkanolamine-water, CO{sub 2}-alkanolamine-water) VLE data. The Data Regression System of ASPEN PLUS, based upon the Maximum Likelihood Principle, was used to estimate adjustable parameters. Ternary system measurements used in parameter estimation ranged in temperature from 25 to 120{degree}C in alkanolamine concentration from 1 to 5 M, in acid gas loading from 0 to 1.5 moles per mole alkanolamine, and in acid gas partial pressure from 0.1 to 1,000 kPa. Maximum likelihood estimates of ternary system H{sub 2} or CO{sub 2} equilibrium partial pressures and liquid phase concentrations were found to be in good agreement with measurements for aqueous solutions of monoethanolamine (MEA), diethanolamine (DEA), diglycolamine (DGA), and methyldiethanolamine (MDEA) indicating that the model successfully represents ternary system data. The model was extended to represent CO{sub 2} solubility in aqueous mixtures of MDEA with MEA or DEA. The solubility was measured at 40 and 80{degree}C over a wide range of CO{sub 2} partial pressures. These measurements were used to estimate additional binary parameters of the mixed solvent systems.

  9. Air-Assisted Liquid Liquid-Microextraction for the Analysis of Fungicides from Environmental Water and Juice Samples.

    PubMed

    Wu, Shiju; Jin, Tingting; Cheng, Jing; Zhou, Hongbin; Cheng, Min

    2015-07-01

    In this work, a rapid method based on air-assisted liquid liquid microextraction (AALLME) was developed for the determination of three fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water and juice samples. A narrow-neck glass tube was made to facilitate collection of the low-density extractant. The mixture of extractant and sample solution is rapidly sucked into a 5-mL glass syringe and then is injected into the narrow-neck glass tube and the procedure is repeated six times. A homogeneous solution was formed and then with the continuous injection of air by a 20-mL glass syringe, phase separation happened and the extractant was collected on the top of the sample solution. No centrifugation separation step was involved. It took only 90 s to complete the pretreatment process. The influence of main factors on the extraction efficiency is studied. Under optimal conditions, enrichment factors for the three fungicides varied from 145 to 178. The limits of detection for azoxystrobin, diethofencarb and pyrimethanil were 0.08, 0.16 and 0.25 µg L(-1), respectively. Reasonable relative recoveries were varied from 72.3 to 108.0%. And satisfactory intra-assay (5.3-6.2%, n = 6) and inter-assay (6.8-9.3%, n = 6) precision illustrated good performance of the analytical procedure. PMID:25355900

  10. Water-in-ionic liquid microemulsion formation in solvent mixture of aprotic and protic imidazolium-based ionic liquids.

    PubMed

    Kusano, Takumi; Fujii, Kenta; Hashimoto, Kei; Shibayama, Mitsuhiro

    2014-10-14

    We report that water-in-ionic liquid microemulsions (MEs) are stably formed in an organic solvent-free system, i.e., a mixture of aprotic (aIL) and protic (pIL) imidazolium-based ionic liquids (ILs) containing the anionic surfactant dioctyl sulfosuccinate sodium salt (AOT). Structural investigations using dynamic light, small-angle X-ray, and small-angle neutron scatterings were performed for MEs formed in mixtures of aprotic 1-octyl-3-methylimidazolium ([C8mIm(+)]) and protic 1-alkylimidazolium ([CnImH(+)], n = 4 or 8) IL with a common anion, bis(trifluoromethanesulfonyl)amide ([TFSA(-)]). It was found that the ME structure strongly depends on the mixing composition of the aIL/pIL in the medium. The ME size appreciably increases with increasing pIL content in both [C8mIm(+)][TFSA(-)]/[C8ImH(+)][TFSA(-)] and [C8mIm(+)][TFSA(-)]/[C4ImH(+)][TFSA(-)] mixtures. The size is larger for the n = 8 system than that for the n = 4 system. These results indicate that the shell part of MEs is composed of both AOT and pIL cation, and the ME size can be tuned by pIL content in the aIL/pIL mixtures. PMID:25226398

  11. Self-assembly of azobenzene bilayer membranes in binary ionic liquid-water nanostructured media.

    PubMed

    Kang, Tejwant Singh; Ishiba, Keita; Morikawa, Masa-aki; Kimizuka, Nobuo

    2014-03-11

    Anionic azobenzene-containing amphiphile 1 (sodium 4-[4-(N-methyl-N-dodecylamino)phenylazo]benzenesulfonate) forms ordered bilayer membranes in binary ionic liquid (1-ethyl-3-methylimidazolium ethyl sulfate, [C2mim][C2OSO3])-water mixtures. The binary [C2mim][C2OSO3]-water mixture is macroscopically homogeneous at any mixing ratio; however, it possesses fluctuating nanodomains of [C2mim][C2OSO3] molecules as observed by dynamic light scattering (DLS). These nanodomains show reversible heat-induced mixing behavior with water. Although the amphiphile 1 is substantially insoluble in pure water, it is dispersible in the [C2mim][C2OSO3]-water mixtures. The concentration of [C2mim][C2OSO3] and temperature exert significant influences on the self-assembling characteristics of 1 in the binary media, as shown by DLS, transmission electron microscopy (TEM), UV-vis spectroscopy, and zeta-potential measurements. Bilayer membranes with rod- or dotlike nanostructures were formed at a lower content of [C2mim][C2OSO3] (2-30 v/v %), in which azobenzene chromophores adopt parallel molecular orientation regardless of temperature. In contrast, when the content of [C2mim][C2OSO3] is increased above 60 v/v %, azobenzene bilayers showed thermally reversible gel-to-liquid crystalline phase transition. The self-assembly of azobenzene amphiphiles is tunable depending on the volume fraction of [C2mim][C2OSO3] and temperature, which are associated with the solvation by nanoclusters in the binary [C2mim][C2OSO3]-water media. These observations clearly indicate that mixtures of water-soluble ionic liquids and water provide unique and valiant environments for ordered molecular self-assembly. PMID:24528277

  12. Interfacial spreading effects on one-dimensional organic liquid imbibition in water-wetted porous media

    NASA Astrophysics Data System (ADS)

    McBride, J. F.; Simmons, C. S.; Cary, J. W.

    1992-10-01

    The spreading coefficient, Csp, determines whether an organic immiscible liquid, OIL, will form a lens ( Csp < 0) or will spread spontaneously ( Csp > 0) on a water surface. An OIL that forms a lens does not perfectly wet the water surface and therefore has a contact angle greater than 0°. The one-dimensional rate at which an OIL spreads spontaneously on a water surface is proportional to the square root of Csp. Of the OIL's that pose a contaminant threat to the subsurface, the majority has a non-zero Csp. To test the influence of such interfacial spreading phenomena on OIL infiltration in a pristine vadose zone, upward OIL and water imbibition infiltration experiments were performed in glass-bead columns, moistened with water, by using OIL's with different Csp. An analytical model for saturated liquid front rise was used to inversely estimate the effective capillary pressure head at the front and the average liquid conductivity. A nonspreading OIL ( Csp ≪ 0) exhibited a reduced capillary pressure head in the water-wetted glass beads. A spontaneously spreading OIL ( Csp ≫0) manifested an enhanced capillary pressure head. Reduced capillary pressure head was associated with an increase in average conductivity, and enhanced capillary pressure head was associated with a decrease in average conductivity when compared to the average water conductivity during water imbibition. The employed experimental method and mathematical analysis of dynamic flow, subject to interfacial spreading phenomena, are practical for quantifying parameters for use in sharp-front OIL infiltration models, but more research is needed to determine how to incorporate the spreading coefficient in numerical multiphase flow models.

  13. Structural properties of geminal dicationic ionic liquid/water mixtures: a theoretical and experimental insight.

    PubMed

    Serva, Alessandra; Migliorati, Valentina; Lapi, Andrea; Aquilanti, Giuliana; Arcovito, Alessandro; D'Angelo, Paola

    2016-06-28

    The structural behavior of geminal dicationic ionic liquid 1,n-bis[3-methylimidazolium-1-yl] alkane bromide ([Cn(mim)2]Br2)/water mixtures has been studied using extended X-ray absorption fine structure (EXAFS) spectroscopy in combination with molecular dynamics (MD) simulations. The properties of the mixtures are investigated as a function of both water concentration and alkyl-bridge chain length. The very good agreement between the EXAFS experimental data and the theoretical curves calculated from the MD structural results has proven the validity of the theoretical framework used for all of the investigated systems. In all the solutions the water molecules are preferentially coordinated with the Br(-) ion, even if a complex network of interactions among dications, anions and water molecules takes place. The local molecular arrangement around the bromide ion is found to change with increasing water content, as more and more water molecules are accomodated in the Br(-) first coordination shell. Moreover, with the decrease of the alkyl-bridge chain length, the interactions between dications and anions increase, with Br(-) forming a bridge between the two imidazolium rings of the same dication. On the other hand, in [Cn(mim)2]Br2/water mixtures with long alkyl-bridge chains peculiar internal arrangements of the dications are found, leading to different structural features of geminal dicationic ionic liquids as compared to their monocationic counterparts. PMID:27272477

  14. Determination of bromate in drinking water by ultraperformance liquid chromatography-tandem mass spectrometry.

    PubMed

    Alsohaimi, Ibrahim Hotan; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan; Abdalla, Mohammad Abulhassan; Busquets, Rosa; Alomary, Ahmad Khodran

    2012-10-01

    Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 μg/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water. PMID:22815069

  15. Estrogenic compounds determination in water samples by dispersive liquid-liquid microextraction and micellar electrokinetic chromatography coupled to mass spectrometry.

    PubMed

    D'Orazio, Giovanni; Asensio-Ramos, María; Hernández-Borges, Javier; Fanali, Salvatore; Rodríguez-Delgado, Miguel Ángel

    2014-05-30

    In this work, a group of 12 estrogenic compounds, i.e., four natural sexual hormones (estrone, 17β-estradiol, 17α-estradiol and estriol), an exoestrogen (17α-ethynylestradiol), a synthetic stilbene (dienestrol), a mycotoxin (zearalenone) and some of their major metabolites (2-methoxyestradiol, α-zearalanol, β-zearalanol, α-zearalenol and β-zearalenol) have been separated and determined by micellar electrokinetic chromatography (MEKC) coupled to electrospray ion trap mass spectrometry. For this purpose, a background electrolyte containing an aqueous solution of 45 mM of perfluorooctanoic acid (PFOA) adjusted to pH 9.0 with an ammonia solution, as MS friendly surfactant, and methanol (10% (v/v)), as organic modifier, was used. To further increase the sensitivity, normal stacking mode was applied by injecting the sample dissolved in an aqueous solution of 11.5mM of ammonium PFO (APFO) at pH 9.0 containing 10% (v/v) of methanol for 25s. Dispersive liquid-liquid microextraction, using 110 μL of chloroform and 500 μL of acetonitrile as extraction and dispersion solvents, respectively, was employed to extract and preconcentrate the target analytes from different types of environmental water samples (mineral, run-off and wastewater) containing 30% (w/v) NaCl and adjusted to pH 3.0 with 1M HCl. The limits of detection achieved were in the range 0.04-1.10 μg/L. The whole method was validated in terms of linearity, precision, recovery and matrix effect for each type of water, showing determination coefficients higher than 0.992 for matrix-matched calibration and absolute recoveries in the range 43-91%. PMID:24780255

  16. Polymorphism of phosphoric oxide

    USGS Publications Warehouse

    Hill, W.L.; Faust, G.T.; Hendricks, S.B.

    1943-01-01

    The melting points and monotropic relationship of three crystalline forms of phosphoric oxide were determined by the method of quenching. Previous vapor pressure data are discussed and interpreted to establish a pressure-temperature diagram (70 to 600??) for the one-component system. The system involves three triple points, at which solid, liquid and vapor (P4O10) coexist in equilibrium, namely: 420?? and 360 cm., 562?? and 43.7 cm. and 580?? and 55.5 cm., corresponding to the hexagonal, orthorhombic and stable polymorphs, respectively, and at least two distinct liquids, one a stable polymer of the other, which are identified with the melting of the stable form and the hexagonal modification, respectively. Indices of refraction of the polymorphs and glasses were determined. The density and the thermal, hygroscopic and structural properties of the several phases are discussed.

  17. A high-resolution XAS study of aqueous Cu(II) in liquid and frozen solutions: Pyramidal, polymorphic, and non-centrosymmetric

    NASA Astrophysics Data System (ADS)

    Frank, Patrick; Benfatto, Maurizio; Qayyam, Munzarin; Hedman, Britt; Hodgson, Keith O.

    2015-02-01

    High-resolution EXAFS (k = 18 Å-1) and MXAN XAS analyses show that axially elongated square pyramidal [Cu(H2O)5]2+ dominates the structure of Cu(II) in aqueous solution, rather than 6-coordinate JT-octahedral [Cu(H2O)6]2+. Freezing produced a shoulder at 8989.6 eV on the rising XAS edge and an altered EXAFS spectrum, while 1s → 3d transitions remained invariant in energy position and intensity. Core square pyramidal [Cu(H2O)5]2+ also dominates frozen solution. Solvation shells were found at ˜3.6 Å (EXAFS) or ˜3.8 Å (MXAN) in both liquid and frozen phases. However, MXAN analysis revealed that about half the time in liquid solution, [Cu(H2O)5]2+ associates with an axially non-bonding 2.9 Å water molecule. This distant water apparently organizes the solvation shell. When the 2.9 Å water molecule is absent, the second shell is undetectable to MXAN. The two structural arrangements may represent energetic minima of fluxional dissolved aqueous [Cu(H2O)5]2+. The 2.9 Å trans-axial water resolves an apparent conflict of the [Cu(H2O)5]2+ core model with a dissociational exchange mechanism. In frozen solution, [Cu(H2O)5]2+ is associated with either a 3.0 Å axial non-bonded water molecule or an axial ClO4- at 3.2 Å. Both structures are again of approximately equal presence. When the axial ClO4- is present, Cu(II) is ˜0.5 Å above the mean O4 plane. This study establishes [Cu(H2O)5]2+ as the dominant core structure for Cu(II) in water solution, and is the first to both empirically resolve multiple extended solution structures for fluxional [Cu(H2O)5]2+ and to provide direct evidence for second shell dynamics.

  18. A high-resolution XAS study of aqueous Cu(II) in liquid and frozen solutions: Pyramidal, polymorphic, and non-centrosymmetric

    PubMed Central

    Benfatto, Maurizio; Qayyam, Munzarin; Hedman, Britt; Hodgson, Keith O.

    2015-01-01

    High-resolution EXAFS (k = 18 Å−1) and MXAN XAS analyses show that axially elongated square pyramidal [Cu(H2O)5]2+ dominates the structure of Cu(II) in aqueous solution, rather than 6-coordinate JT-octahedral [Cu(H2O)6]2+. Freezing produced a shoulder at 8989.6 eV on the rising XAS edge and an altered EXAFS spectrum, while 1s → 3d transitions remained invariant in energy position and intensity. Core square pyramidal [Cu(H2O)5]2+ also dominates frozen solution. Solvation shells were found at ∼3.6 Å (EXAFS) or ∼3.8 Å (MXAN) in both liquid and frozen phases. However, MXAN analysis revealed that about half the time in liquid solution, [Cu(H2O)5]2+ associates with an axially non-bonding 2.9 Å water molecule. This distant water apparently organizes the solvation shell. When the 2.9 Å water molecule is absent, the second shell is undetectable to MXAN. The two structural arrangements may represent energetic minima of fluxional dissolved aqueous [Cu(H2O)5]2+. The 2.9 Å trans-axial water resolves an apparent conflict of the [Cu(H2O)5]2+ core model with a dissociational exchange mechanism. In frozen solution, [Cu(H2O)5]2+ is associated with either a 3.0 Å axial non-bonded water molecule or an axial ClO4− at 3.2 Å. Both structures are again of approximately equal presence. When the axial ClO4− is present, Cu(II) is ∼0.5 Å above the mean O4 plane. This study establishes [Cu(H2O)5]2+ as the dominant core structure for Cu(II) in water solution, and is the first to both empirically resolve multiple extended solution structures for fluxional [Cu(H2O)5]2+ and to provide direct evidence for second shell dynamics. PMID:25725734

  19. Seasonally-Active Water on Mars: Vapour, Ice, Adsorbate, and the Possibility of Liquid

    NASA Astrophysics Data System (ADS)

    Richardson, M. I.

    2002-12-01

    southern caps. Similar climate-models of the water cycle also do not need much exchangeable adsorbed water in order to explain the observed vapour distributions. The possibility of liquid water is tantalizing, but difficult to definitively judge. On scales greater than a meter or so, Mars is most definitely well away from the water triple point--although the surface pressure can exceed 6.1 mbars, the partial pressure of water vapor (to which the triple point refers) is at best orders of magnitude lower. Several careful studies have shown, however, that locally transient (meta-stable) liquid is possible, if the net heating of ice deposits is high enough. This process is aided if the total surface pressure exceeds 6.1mbar (this prevents boiling, or the explosive loss of vapour into the atmosphere) or if the liquid is covered by a thin ice shell, and is only possible if surface temperatures exceed 273K (for pure water, or the appropriate eutectic for brines) and if ice is present. The former challenge is much easier to meet than the latter. The melt scenario requires that ice deposited in winter must be protected from sublimation as surface temperatures increase in spring, but then exposed to the peak of solar heating in summer. Available spacecraft observations of seasonal water will be discussed with the aid of GCM model simulations, and examined in the context of water distributions and phases.

  20. Transient Liquid Water as a Mechanism for Induration of Soil Crusts on Mars

    NASA Technical Reports Server (NTRS)

    Landis, G. A.; Blaney, D.; Cabrol, N.; Clark, B. C.; Farmer, J.; Grotzinger, J.; Greeley, R.; McLennan, S. M.; Richter, L.; Yen, A.

    2004-01-01

    The Viking and the Mars Exploration Rover missions observed that the surface of Mars is encrusted by a thinly cemented layer tagged as "duricrust". A hypothesis to explain the formation of duricrust on Mars should address not only the potential mechanisms by which these materials become cemented, but also the textural and compositional components of cemented Martian soils. Elemental analyzes at five sites on Mars show that these soils have sulfur content of up to 4%, and chlorine content of up to 1%. This is consistent with the presence of sulfates and halides as mineral cements. . For comparison, the rock "Adirondack" at the MER site, after the exterior layer was removed, had nearly five times lower sulfur and chlorine content , and the Martian meteorites have ten times lower sulfur and chlorine content, showing that the soil is highly enriched in the saltforming elements compared with rock.Here we propose two alternative models to account for the origin of these crusts, each requiring the action of transient liquid water films to mediate adhesion and cementation of grains. Two alternative versions of the transient water hypothesis are offered, a top down hypothesis that emphasizes the surface deposition of frost, melting and downward migration of liquid water and a bottom up alternative that proposes the presence of interstitial ice/brine, with the upward capillary migration of liquid water.

  1. The Microscopic Physical Cause for the Density Maximum of Liquid Water.

    PubMed

    Tröster, Philipp; Tavan, Paul

    2014-01-01

    The existence of a density maximum at 277 K is probably the most prominent anomaly among the many very special thermodynamic properties of liquid water. While usually attributed to so-called hydrogen bonding, the microscopic physical cause of this prominent anomaly is still elusive. Here we show that the density anomaly is caused by those short-range electrostatic forces, which are generated by the quadrupole and higher moments of the charge distributions present in liquid-phase water molecules. This conclusion derives from 20 ns replica exchange molecular-dynamics simulations with closely related polarizable four-, five-, and six-point water models. As soon as the model complexity suffices to represent the higher electrostatic moments with sufficient accuracy, the density temperature profile n(T) calculated for T ∈ [250,320] K at the standard pressure 1 bar locks in to the experimental observation. The corresponding six-point model is, therefore, the most simple available cartoon for liquid-phase water molecules. PMID:26276193

  2. First Principles Simulations of the Infrared Spectrum of Liquid Water Using Hybrid Density Functionals.

    PubMed

    Zhang, Cui; Donadio, Davide; Gygi, François; Galli, Giulia

    2011-05-10

    We show that first principles hybrid functional (PBE0) simulations of the infrared spectrum of liquid water yields a much better agreement with experimental results than a semilocal functional description; in particular, the quantitative accord with measured stretching and bending bands is very good. Such an improved description stems from two effects: a more accurate account, at the PBE0 level of theory, of the vibrational properties of the monomer and dimer and an underlying structural model for the liquid with a smaller number of hydrogen bonds and oxygen coordination than those obtained with semilocal functionals. The average electronic gap of the liquid is increased by 60% with respect to the PBE value, when computed at the PBE0 level of theory, and is in fair agreement with experimental results. PMID:26610134

  3. Absorption spectra and photolysis of methyl peroxide in liquid and frozen water.

    PubMed

    Epstein, Scott A; Shemesh, Dorit; Tran, Van T; Nizkorodov, Sergey A; Gerber, R Benny

    2012-06-21

    Methyl peroxide (CH(3)OOH) is commonly found in atmospheric waters and ices in significant concentrations. It is the simplest organic peroxide and an important precursor to hydroxyl radical. Many studies have examined the photochemical behavior of gaseous CH(3)OOH; however, the photochemistry of liquid and frozen water solutions is poorly understood. We present a series of experiments and theoretical calculations designed to elucidate the photochemical behavior of CH(3)OOH dissolved in liquid water and ice over a range of temperatures. The molar extinction coefficients of aqueous CH(3)OOH are different from the gas phase, and they do not change upon freezing. Between -12 and 43 °C, the quantum yield of CH(3)OOH photolysis is described by the following equation: Φ(T) = exp((-2175 ± 448)1/T) + 7.66 ± 1.56). We use on-the-fly ab initio molecular dynamics simulations to model structures and absorption spectra of a bare CH(3)OOH molecule and a CH(3)OOH molecule immersed inside 20 water molecules at 50, 200, and 220 K. The simulations predict large sensitivity in the absorption spectrum of CH(3)OOH to temperature, with the spectrum narrowing and shifting to the blue under cryogenic conditions because of constrained dihedral motion around the O-O bond. The shift in the absorption spectrum is not observed in the experiment when the CH(3)OOH solution is frozen suggesting that CH(3)OOH remains in a liquid layer between the ice grains. Using the extinction coefficients and photolysis quantum yields obtained in this work, we show that under conditions with low temperatures, in the presence of clouds with a high liquid-water content and large solar zenith angles, the loss of CH(3)OOH by aqueous photolysis is responsible for up to 20% of the total loss of CH(3)OOH due to photolysis. Gas phase photolysis of CH(3)OOH dominates under all other conditions. PMID:22217262

  4. Determination of selected azaarenes in water by bonded-phase extraction and liquid chromatography

    USGS Publications Warehouse

    Steinheimer, T.R.; Ondrus, M.G.

    1986-01-01

    A method for the rapid and simple quantitative determination of quinoline, isoquinoline, and five selected three-ring azaarenes in water has been developed. The azaarene fraction is separated from its carbon analogues on n-octadecyl packing material by edition with acidified water/acetonitrile. Concentration as great as 1000-fold is achieved readily. Instrumental analysis involves high-speed liquid chromatography on flexible-walled, wide-bore columns with fluorescence and ultraviolet detection at several wavelengths employing filter photometers in series. Method-validation data is provided as azaarene recovery efficiency from fortified samples. Distilled water, river water, contaminated ground water, and secondary-treatment effluent have been tested. Recoveries at part-per-billion levels are nearly quantitative for the three-ring compounds, but they decrease for quinoline and isoquinoline. ?? 1986 American Chemical Society.

  5. Growth of volcanic ash aggregates in the presence of liquid water and ice: an experimental approach

    NASA Astrophysics Data System (ADS)

    Van Eaton, Alexa R.; Muirhead, James D.; Wilson, Colin J. N.; Cimarelli, Corrado

    2012-11-01

    Key processes influencing the aggregation of volcanic ash and hydrometeors are examined with an experimental method employing vibratory pan aggregation. Mechanisms of aggregation in the presence of hail and ice pellets, liquid water (≤30 wt%), and mixed water phases are investigated at temperatures of 18 and -20 °C. The experimentally generated aggregates, examined in hand sample, impregnated thin sections, SEM imagery, and X-ray microtomography, closely match natural examples from phreatomagmatic phases of the 27 ka Oruanui and 2010 Eyjafjallajökull eruptions. Laser diffraction particle size analysis of parent ash and aggregates is also used to calculate the first experimentally derived aggregation coefficients that account for changing liquid water contents and subzero temperatures. These indicate that dry conditions (<5-10 wt% liquid) promote strongly size selective collection of sub-63 μm particles into aggregates (given by aggregation coefficients >1). In contrast, liquid-saturated conditions (>15-20 wt% liquid) promote less size selective processes. Crystalline ice was also capable of preferentially selecting volcanic ash <31 μm under liquid-free conditions in a two-stage process of electrostatic attraction followed by ice sintering. However, this did not accumulate more than a monolayer of ash at the ice surface. These quantitative relationships may be used to predict the timescales and characteristics of aggregation, such as aggregate size spectra, densities, and constituent particle size characteristics, when the initial size distribution and water content of a volcanic cloud are known. The presence of an irregularly shaped, millimeter-scale vacuole at the center of natural aggregates was also replicated during interaction of ash and melting ice pellets, followed by sublimation. Fine-grained rims were formed by adding moist aggregates to a dry mixture of sub-31 μm ash, which adhered by electrostatic forces and sparse liquid bridges. From this, we

  6. In situ separation of root hydraulic redistribution of soil water from liquid and vapor transport

    SciTech Connect

    Warren, Jeffrey; Brooks, J Renee; Dragila, Maria; Meinzer, Rick

    2011-01-01

    Nocturnal increases in water potential ( ) and water content (WC) in the upper soil profile are often attributed to root water efflux into the soil, a process termed hydraulic lift or hydraulic redistribution (HR). We have previously reported HR values up to ~0.29 mm day-1 in the upper soil for a seasonally dry old-growth ponderosa pine site. However, unsaturated liquid or vapor flux of water between soil layers independent of roots also contributes to the diurnal patterns in WC, confounding efforts to determine the actual magnitude of HR. In this study, we estimated liquid (Jl) and vapor (Jv) soil water fluxes and their impacts on quantifying HR in situ by applying existing data sets of , WC, temperature (T) and soil physical properties to soil water transport equations. Under moist conditions, Jl between layers was estimated to be larger than necessary to account for measured nocturnal increases in WC of upper soil layers. However, as soil drying progressed unsaturated hydraulic conductivity declined rapidly such that Jl was irrelevant (< 2E-06 cm hr-1 at 0-60 cm depths) to total water flux by early August. In surface soil at depths above 15 cm, large T fluctuations can impact Jv leading to uncertainty concerning the role, if any, of HR in nocturnal WC dynamics. Vapor flux was estimated to be the highest at the shallowest depths measured (20 - 30 cm) where it could contribute up to 40% of hourly increases in nocturnal soil moisture depending on thermal conditions. While both HR and net soil water flux between adjacent layers contribute to WC in the 15-65 cm soil layer, HR was the dominant process and accounted for at least 80% of the diurnal increases in WC. While the absolute magnitude of HR is not easily quantified, total diurnal fluctuations in upper soil water content can be quantified and modeled, and remain highly applicable for establishing the magnitude and temporal dynamics of total ecosystem water flux.

  7. In situ separation of root hydraulic redistribution of soil water from liquid and vapor transport.

    PubMed

    Warren, Jeffrey M; Brooks, J Renée; Dragila, Maria I; Meinzer, Frederick C

    2011-08-01

    Nocturnal increases in water potential (ψ) and water content (θ) in the upper soil profile are often attributed to root water efflux, a process termed hydraulic redistribution (HR). However, unsaturated liquid or vapor flux of water between soil layers independent of roots also contributes to the daily recovery in θ (Δθ), confounding efforts to determine the actual magnitude of HR. We estimated liquid (J(l)) and vapor (J(v)) soil water fluxes and their impacts on quantifying HR in a seasonally dry ponderosa pine (Pinus ponderosa) forest by applying existing datasets of ψ, θ and temperature (T) to soil water transport equations. As soil drying progressed, unsaturated hydraulic conductivity declined rapidly such that J (l) was irrelevant (<2E-05 mm h(-1) at 0-60 cm depths) to total water flux by early August. Vapor flux was estimated to be the highest in upper soil (0-15 cm), driven by large T fluctuations, and confounded the role of HR, if any, in nocturnal θ dynamics. Within the 15-35 cm layer, J(v) contributed up to 40% of hourly increases in nocturnal soil moisture. While both HR and net soil water flux between adjacent layers contribute to θ in the 15-65 cm soil layer, HR was the dominant process and accounted for at least 80% of the daily recovery in θ. The absolute magnitude of HR is not easily quantified, yet total diurnal fluctuations in upper soil water content can be quantified and modeled, and remain highly applicable for establishing the magnitude and temporal dynamics of total ecosystem water flux. PMID:21400193

  8. Remote measurements of ozone, water vapor and liquid water content, and vertical profiles of temperature in the lower troposphere

    NASA Technical Reports Server (NTRS)

    Grant, W. B.; Gary, B. L.; Shumate, M. S.

    1983-01-01

    Several advanced atmospheric remote sensing systems developed at the Jet Propulsion Laboratory were demonstrated under various field conditions to determine how useful they would be for general use by the California Air Resources Board and local air quality districts. One of the instruments reported on is the Laser Absorption Spectrometer (LAS). It has a pair of carbon dioxide lasers with a transmitter and receiver and can be flown in an aircraft to measure the column abundance of such gases as ozone. From an aircraft, it can be used to rapidly survey a large region. The LAS is usually operated from an aircraft, although it can also be used at a fixed location on the ground. Some tests were performed with the LAS to measure ozone over a 2-km horizontal path. Another system reported on is the Microwave Atmospheric Remote Sensing System (MARS). It is tuned to microwave emissions from water vapor, liquid water, and oxygen molecules (for atmospheric temperature). It can measure water vapor and liquid water in the line-of-sight, and can measure the vertical temperature profile.

  9. Sum-frequency generation analyses of the structure of water at amphoteric SAM-liquid water interfaces.

    PubMed

    Nomura, Kouji; Nakaji-Hirabayashi, Tadashi; Gemmei-Ide, Makoto; Kitano, Hiromi; Noguchi, Hidenori; Uosaki, Kohei

    2014-09-01

    Surfaces of both a cover glass and the flat plane of a semi-cylindrical quartz prism were modified with a mixture of positively and negatively charged silane coupling reagents (3-aminopropyltriethoxysilane (APTES) and 3-(trihydroxysilyl)propylmethylphosphonate (THPMP), respectively). The glass surface modified with a self-assembled monolayer (SAM) prepared at a mixing ratio of APTES:THPMP=4:6 was electrically almost neutral and was resistant to non-specific adsorption of proteins, whereas fibroblasts gradually adhered to an amphoteric (mixed) SAM surface probably due to its stiffness, though the number of adhered cells was relatively small. Sum frequency generation (SFG) spectra indicated that total intensity of the OH stretching region (3000-3600cm(-1)) for the amphoteric SAM-modified quartz immersed in liquid water was smaller than those for the positively and negatively charged SAM-modified quartz prisms and a bare quartz prism in contact with liquid water. These results suggested that water molecules at the interface of water and an amphoteric SAM-modified quartz prism are not strongly oriented in comparison with those at the interface of a lopsidedly charged SAM-modified quartz prism and bare quartz. The importance of charge neutralization for the anti-biofouling properties of solid materials was strongly suggested. PMID:25001187

  10. Two-channel microwave radiometer for observations of total column precipitable water vapor and cloud liquid water path

    SciTech Connect

    Liljegren, J.C.

    1994-01-01

    The Atmospheric Radiation Measurement (ARM) Program is focused on improving the treatment of radiation transfer in models of the atmospheric general circulation, as well as on improving parameterizations of cloud properties and formation processes in these models (USDOE, 1990). To help achieve these objectives, ARM is deploying several two-channel, microwave radiometers at the Cloud and Radiation Testbed (CART) site in Oklahoma for the purpose of obtaining long time series observations of total precipitable water vapor (PWV) and cloud liquid water path (LWP). The performance of the WVR-1100 microwave radiometer deployed by ARM at the Oklahoma CART site central facility to provide time series measurements precipitable water vapor (PWV) and liquid water path (LWP) has been presented. The instrument has proven to be durable and reliable in continuous field operation since June, 1992. The accuracy of the PWV has been demonstrated to achieve the limiting accuracy of the statistical retrieval under clear sky conditions, degrading with increasing LWP. Improvements are planned to address moisture accumulation on the Teflon window, as well as to identity the presence of clouds with LWP at or below the retrieval uncertainty.

  11. Liquid-Water Uptake and Removal in PEM Fuel-Cell Components

    SciTech Connect

    Das, Prodip K.; Gunterman, Haluna P.; Kwong, Anthony; Weber, Adam Z.

    2011-09-23

    Management of liquid water is critical for optimal fuel-cell operation, especially at low temperatures. It is therefore important to understand the wetting properties and water holdup of the various fuel-cell layers. While the gas-diffusion layer is relatively hydrophobic and exhibits a strong intermediate wettability, the catalyst layer is predominantly hydrophilic. In addition, the water content of the ionomer in the catalyst layer is lower than that of the bulk membrane, and is affected by platinum surfaces. Liquid-water removal occurs through droplets on the surface of the gas-diffusion layer. In order to predict droplet instability and detachment, a force balance is used. While the pressure or drag force on the droplet can be derived, the adhesion or surface-tension force requires measurement using a sliding-angle approach. It is shown that droplets produced by forcing water through the gas-diffusion layer rather than placing them on top of it show much stronger adhesion forces owing to the contact to the subsurface water.

  12. Characterization of the Local Structure in Liquid Water by Various Order Parameters

    PubMed Central

    2015-01-01

    A wide range of geometric order parameters have been suggested to characterize the local structure of liquid water and its tetrahedral arrangement, but their respective merits have remained elusive. Here, we consider a series of popular order parameters and analyze molecular dynamics simulations of water, in the bulk and in the hydration shell of a hydrophobic solute, at 298 and 260 K. We show that these parameters are weakly correlated and probe different distortions, for example the angular versus radial disorders. We first combine these complementary descriptions to analyze the structural rearrangements leading to the density maximum in liquid water. Our results reveal no sign of a heterogeneous mixture and show that the density maximum arises from the depletion in interstitial water molecules upon cooling. In the hydration shell of the hydrophobic moiety of propanol, the order parameters suggest that the water local structure is similar to that in the bulk, with only a very weak depletion in ordered configurations, thus confirming the absence of any iceberg-type structure. Finally, we show that the main structural fluctuations that affect water reorientation dynamics in the bulk are angular distortions, which we explain by the jump hydrogen-bond exchange mechanism. PMID:26054933

  13. Why many semiempirical molecular orbital theories fail for liquid water and how to fix them.

    PubMed

    Welborn, Matthew; Chen, Jiahao; Wang, Lee-Ping; Van Voorhis, Troy

    2015-05-01

    Water is an extremely important liquid for chemistry and the search for more accurate force fields for liquid water continues unabated. Neglect of diatomic differential overlap (NDDO) molecular orbital methods provide and intriguing generalization of classical force fields in this regard because they can account both for bond breaking and electronic polarization of molecules. However, we show that most standard NDDO methods fail for water because they give an incorrect description of hydrogen bonding, water's key structural feature. Using force matching, we design a reparameterized NDDO model and find that it qualitatively reproduces the experimental radial distribution function of water, as well as various monomer, dimer, and bulk properties that PM6 does not. This suggests that the apparent limitations of NDDO models are primarily due to poor parameterization and not to the NDDO approximations themselves. Finally, we identify the physical parameters that most influence the condensed phase properties. These results help to elucidate the chemistry that a semiempirical molecular orbital picture of water must capture. We conclude that properly parameterized NDDO models could be useful for simulations that require electronically detailed explicit solvent, including the calculation of redox potentials and simulation of charge transfer and photochemistry. PMID:25766721

  14. Stability Limit of Water by Metastable Vapor-Liquid Equilibrium with Nanoporous Silicon Membranes.

    PubMed

    Chen, I-Tzu; Sessoms, David A; Sherman, Zachary; Choi, Eugene; Vincent, Olivier; Stroock, Abraham D

    2016-06-16

    Liquid can sustain mechanical tension as its pressure drops below the vapor-liquid coexistence line and becomes less than zero, until it reaches the stability limit-the pressure at which cavitation inevitably occurs. For liquid water, its stability limit is still a subject of debate: the results obtained by researchers using a variety of techniques show discrepancies between the values of the stability limit and its temperature dependence as temperature approaches 0 °C. In this work, we present a study of the stability limit of water by the metastable vapor-liquid equilibrium (MVLE) method with nanoporous silicon membranes. We also report on an experimental system which enables tests of the temperature dependence of the stability limit with MVLE. The stability limit we found increases monotonically (larger tension) as temperature approaches 0 °C; this trend contradicts the centrifugal result of Briggs but agrees with the experiments by acoustic cavitation. This result confirms that a quasi-static method can reach stability values similar to that from the dynamic stretching technique, even close to 0 °C. Nevertheless, our results fall in the range of ∼ -20 to -30 MPa, a range that is consistent with the majority of experiments but is far less negative than the limit obtained in experiments involving quartz inclusions and that predicted for homogeneous nucleation. PMID:27223603

  15. Prognostic precipitation with three liquid water classes in the ECHAM5-HAM GCM

    NASA Astrophysics Data System (ADS)

    Sant, V.; Posselt, R.; Lohmann, U.

    2015-03-01

    In order to improve the global representation of rain formation in marine stratiform clouds a new parameterization with three prognostic liquid water classes was implemented into the general circulation model ECHAM5 with the aerosol module HAM. The additionally introduced drizzle class improves the physical representation of the droplet spectrum and more importantly, improves the microphysical processes relevant for precipitation formation compared to the standard parameterization. In order to avoid a mismatch of the liquid and ice phase, the prognostic treatment of snow has been introduced too. This has a significant effect on the amount and altitude of ice clouds, which in turn does not only affect in- and outgoing radiation, but also the parameterized collection rates. With the introduction of a prognostic precipitation scheme a more realistic representation of both liquid and ice phase large-scale precipitation is achieved compared to a diagnostic treatment. An encouraging finding is that the sensitivity of the liquid water path to the anthropogenic aerosol forcing with the prognostic treatment is reduced by about 25%. Although the total net radiative forcing is increased from 1.4±0.4 to 1.6±0.4 W m-2 from the control to the prognostic model version, the difference is within the interannual variability. Altogether the results suggest that the treatment of precipitation in global circulation models has a significant influence on the phase and lifetime of clouds, but also hints towards the uncertainties related to a prognostic precipitation scheme.

  16. Mean-Field Approximation to the Hydrophobic Hydration in the Liquid-Vapor Interface of Water.

    PubMed

    Abe, Kiharu; Sumi, Tomonari; Koga, Kenichiro

    2016-03-01

    A mean-field approximation to the solvation of nonpolar solutes in the liquid-vapor interface of aqueous solutions is proposed. It is first remarked with a numerical illustration that the solvation of a methane-like solute in bulk liquid water is accurately described by the mean-field theory of liquids, the main idea of which is that the probability (Pcav) of finding a cavity in the solvent that can accommodate the solute molecule and the attractive interaction energy (uatt) that the solute would feel if it is inserted in such a cavity are both functions of the solvent density alone. It is then assumed that the basic idea is still valid in the liquid-vapor interface, but Pcav and uatt are separately functions of different coarse-grained local densities, not functions of a common local density. Validity of the assumptions is confirmed for the solvation of the methane-like particle in the interface of model water at temperatures between 253 and 613 K. With the mean-field approximation extended to the inhomogeneous system the local solubility profiles across the interface at various temperatures are calculated from Pcav and uatt obtained at a single temperature. The predicted profiles are in excellent agreement with those obtained by the direct calculation of the excess chemical potential over an interfacial region where the solvent local density varies most rapidly. PMID:26595441

  17. Simulations of solid-liquid friction at ice-Ih/water interfaces

    NASA Astrophysics Data System (ADS)

    Louden, Patrick B.; Gezelter, J. Daniel

    2013-11-01

    We have investigated the structural and dynamic properties of the basal and prismatic facets of the ice Ih/water interface when the solid phase is drawn through the liquid (i.e., sheared relative to the fluid phase). To impose the shear, we utilized a velocity-shearing and scaling approach to reverse non-equilibrium molecular dynamics. This method can create simultaneous temperature and velocity gradients and allow the measurement of transport properties at interfaces. The interfacial width was found to be independent of the relative velocity of the ice and liquid layers over a wide range of shear rates. Decays of molecular orientational time correlation functions gave similar estimates for the width of the interfaces, although the short- and longer-time decay components behave differently closer to the interface. Although both facets of ice are in "stick" boundary conditions in liquid water, the solid-liquid friction coefficients were found to be significantly different for the basal and prismatic facets of ice.

  18. Prognostic precipitation with three liquid water classes in the ECHAM5-HAM GCM

    NASA Astrophysics Data System (ADS)

    Sant, V.; Posselt, R.; Lohmann, U.

    2015-08-01

    A new parameterization with three prognostic liquid water classes was implemented into the general circulation model (GCM) ECHAM5 with the aerosol module HAM in order to improve the global representation of rain formation in marine stratiform clouds. The additionally introduced drizzle class improves the physical representation of the droplet spectrum and, more importantly, improves the microphysical processes relevant for precipitation formation compared to the standard parameterization. In order to avoid a mismatch of the liquid and ice phase, a prognostic treatment of snow has been introduced too. This has a significant effect on the amount and altitude of ice clouds, which in turn affects not only the in- and outgoing radiation but also the parameterized collection rates. With the introduction of a prognostic precipitation scheme, a more realistic representation of both liquid and ice phase large-scale precipitation is achieved compared to a diagnostic treatment. An encouraging finding is that with the prognostic treatment the increase of the liquid water path in response to anthropogenic aerosols is reduced by about 25 %. Although the total net radiative forcing is decreased from -1.3±0.3 to -1.6±0.3 W m-2 from the control to the prognostic model version, the difference is within the interannual variability. Altogether the results suggest that the treatment of precipitation in global circulation models has not only a significant influence on the phase of clouds and their conversion rates, but also hints towards uncertainties related to a prognostic precipitation scheme.

  19. Molecular dynamics of phenol at the liquid-vapor interface of water

    NASA Technical Reports Server (NTRS)

    Pohorille, Andrew; Benjamin, Ilan

    1991-01-01

    Results of molecular dynamics calculations on phenol at the water liquid-vapor interface are presented. The density profile of the center of mass of phenol exhibits a maximum 1 A from the Gibbs surface toward the vapor phase, indicating that the molecule is surface-active. Changes in the profile caused by the interface extend 6 A from the Gibbs surface into the liquid, significantly more than change in the density profile of water. The most probable orientation of the solute at the surface is such that its symmetry axis is perpendicular to the interface with the OH substituent pointing toward the liquid. An additional simulation with benzene shows that this molecule at the surface most often adopts orientations parallel to the interface. Deeper in the liquid all the solutes are preferentially ordered perpendicular to the surface. In the interfacial region the orientational preferences of the solute are primarily determined by cavity formation needed to accommodate the hydrophobic portion of the dissolved molecule.

  20. Use of textile waste water along with liquid NPK fertilizer for production of wheat on saline sodic soils.

    PubMed

    Yaseen, Muhammad; Aziz, Muhammad Zahir; Jafar, Abdul Aleem; Naveed, Muhammad; Saleem, Muhammad

    2016-05-01

    A field experiment in collaboration with a private textile industry (Noor Fatima Fabrics Private (Ltd.), Faisalabad) was conducted to evaluate the effect of disposed water from bleaching unit, printing unit and end drain for improving growth and yield of wheat under saline sodic soil. Textile waste water along with canal water (control) was applied with and without liquid NPK fertilizer. The application of liquid NPK fertilizer with end drain waste water increased plant height, spike length, flag leaf length, root length, number of tillers (m(-2)), number of fertile tillers (m(-2)), 1000 grain weight, grain yield, straw yield and biological yield up to 21, 20, 20, 44, 17, 20, 14, 44, 40 and 41%, respectively compared to canal water (control). Similarly, the NPK uptake in grain was increased up to 15, 30 and 28%, respectively by liquid fertilizer treated end drain water as compare to canal water with liquid fertilizer. Moreover, concentration of different heavy metals particularly Cu, Cr, Pb and Cd was decreased in grains by application of waste water along with liquid NPK. The result may imply that waste water application along with liquid-NPK could be a novel approach for improving growth and yield of wheat in saline sodic soils. PMID:26515426

  1. Acousto-optic method used to control water pollution by miscible liquids

    NASA Astrophysics Data System (ADS)

    Ferria, Kouider; Griani, Lazhar; Laouar, Naamane

    2012-05-01

    An acousto-optic (A.O.) method has been developed for controlling the quality of water mixed by miscible liquids like acetone or ethanol… The liquid mixture is filled in a rectangular glass cell, which is placed orthogonally to the incident collimated beam of light. This cell consists of a piezoelectric transducer for generating ultrasonic waves. The collimated light while passing through this cell undergoes a diffraction phenomenon. The diffracted dots are collected by a converging photographic objective and displayed in its back focal plane. The location of the diffracted dots and their intensity are sensitive to any variation of the interaction medium. This result leads to decide about the quality of the water.

  2. Covalency of hydrogen bonds in liquid water can be probed by proton nuclear magnetic resonance experiments

    PubMed Central

    Elgabarty, Hossam; Khaliullin, Rustam Z.; Kühne, Thomas D.

    2015-01-01

    The concept of covalency is widely used to describe the nature of intermolecular bonds, to explain their spectroscopic features and to rationalize their chemical behaviour. Unfortunately, the degree of covalency of an intermolecular bond cannot be directly measured in an experiment. Here we established a simple quantitative relationship between the calculated covalency of hydrogen bonds in liquid water and the anisotropy of the proton magnetic shielding tensor that can be measured experimentally. This relationship enabled us to quantify the degree of covalency of hydrogen bonds in liquid water using the experimentally measured anisotropy. We estimated that the amount of electron density transferred between molecules is on the order of 10  m while the stabilization energy due to this charge transfer is ∼15 kJ mol−1. The physical insight into the fundamental nature of hydrogen bonding provided in this work will facilitate new studies of intermolecular bonding in a variety of molecular systems. PMID:26370179

  3. Ab initio molecular dynamics simulation of liquid water by quantum Monte Carlo

    SciTech Connect

    Zen, Andrea; Luo, Ye Mazzola, Guglielmo Sorella, Sandro; Guidoni, Leonardo

    2015-04-14

    Although liquid water is ubiquitous in chemical reactions at roots of life and climate on the earth, the prediction of its properties by high-level ab initio molecular dynamics simulations still represents a formidable task for quantum chemistry. In this article, we present a room temperature simulation of liquid water based on the potential energy surface obtained by a many-body wave function through quantum Monte Carlo (QMC) methods. The simulated properties are in good agreement with recent neutron scattering and X-ray experiments, particularly concerning the position of the oxygen-oxygen peak in the radial distribution function, at variance of previous density functional theory attempts. Given the excellent performances of QMC on large scale supercomputers, this work opens new perspectives for predictive and reliable ab initio simulations of complex chemical systems.

  4. Shock Hugoniot equations of state for binary water-alcohol liquid mixtures

    NASA Astrophysics Data System (ADS)

    Moore, David; Bolme, Cynthia; Brown, Kathryn; McGrane, Shawn; Schulze, Peter

    2015-06-01

    Shock Hugoniot data were obtained using laser generated shock and ultrafast dynamic ellipsometry (UDE) methods for several non-ideal water-alcohol liquid mixtures, using methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and t-butanol (a.k.a., 2-methyl-2-propanol or tert-butanol). The sound speeds of the mixtures were obtained using Brillouin scattering when not available in the literature. The shock and particle velocities obtained from the UDE data were compared to expectations of the universal liquid Hugoniot (ULH) and to literature shock (plate impact) data where available. The shock Hugoniot trends for all these mixtures, represented as deviations from predictions of the ULH, versus fraction of alcohol are quite similar to each other and suggest that complex hydrogen bonding networks in water-alcohol mixtures alter the compressibility of the mixtures. Data and trends will be presented. LA-UR-15-20328.

  5. The effects of charge transfer on the properties of liquid water

    SciTech Connect

    Lee, Alexis J.; Rick, Steven W.

    2011-05-14

    A method for treating charge transfer interactions in classical potential models is developed and applied to water. In this method, a discrete amount of charge is transferred for each hydrogen bond formed. It is designed to be simple to implement, to be applicable to a variety of potential models, and to satisfy various physical requirements. The method does not transfer charge at large intramolecular distances, it does not result in a conductive liquid, and it can be easily parameterized to give the correct amount of charge transfer. Two charge transfer models are developed for a polarizable and a non-polarizable potential. The models reproduce many of the properties of liquid water, including the structure, the diffusion constant, and thermodynamic properties over a range of temperatures.

  6. Liquid water content and droplet size calibration of the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Ide, Robert F.

    1989-01-01

    The icing research tunnel at the NASA Lewis Research Center underwent a major rehabilitation in 1986 to 1987, necessitating recalibration of the icing cloud. The methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content are described. PMS Forward Scattering Spectrometer and Optical Array probes were used for measurement of droplet size. Examples of droplet size distributions are shown for several median volumetric diameters. Finally, the liquid water content/droplet size operating envelopes of the icing tunnel are shown for a range of airspeeds and are compared to the FAA icing certification criteria.

  7. Liquid water content and droplet size calibration of the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Ide, Robert F.

    1990-01-01

    The icing research tunnel at the NASA Lewis Research Center underwent a major rehabilitation in 1986 to 1987, necessitating recalibration of the icing cloud. The methods used in the recalibration, including the procedure used to establish a uniform icing cloud and the use of a standard icing blade technique for measurement of liquid water content are described. PMS Forward Scattering Spectrometer and Optical Array probes were used for measurement of droplet size. Examples of droplet size distributions are shown for several median volumetric diameters. Finally, the liquid water content/droplet size operating envelopes of the icing tunnel are shown for a range of airspeeds and are compared to the FAA icing certification criteria.

  8. Covalency of hydrogen bonds in liquid water can be probed by proton nuclear magnetic resonance experiments.

    PubMed

    Elgabarty, Hossam; Khaliullin, Rustam Z; Kühne, Thomas D

    2015-01-01

    The concept of covalency is widely used to describe the nature of intermolecular bonds, to explain their spectroscopic features and to rationalize their chemical behaviour. Unfortunately, the degree of covalency of an intermolecular bond cannot be directly measured in an experiment. Here we established a simple quantitative relationship between the calculated covalency of hydrogen bonds in liquid water and the anisotropy of the proton magnetic shielding tensor that can be measured experimentally. This relationship enabled us to quantify the degree of covalency of hydrogen bonds in liquid water using the experimentally measured anisotropy. We estimated that the amount of electron density transferred between molecules is on the order of 10  m while the stabilization energy due to this charge transfer is ∼15 kJ mol(-1). The physical insight into the fundamental nature of hydrogen bonding provided in this work will facilitate new studies of intermolecular bonding in a variety of molecular systems. PMID:26370179

  9. Thickness Measurement Device for Ice, or Ice Mixed with Water or Other Liquid

    NASA Technical Reports Server (NTRS)

    Weinstein, Leonard M. (Inventor)

    2001-01-01

    A Device and Method are provide for determining the thickness of a layer of solid ice, a mixture of ice and water, or a mixture of ice arid other liquid, accumulated on the outer surface of an object. First and second total impedance sensors are operated at first and second frequencies. Corresponding first and second AC total impedance measuring circuits are coupled to The first and second sensors to produce output voltages based on the total impedance changes sensed by the sensors. A processor is coupled to the first and second measuring circuits to generate an output value using the measured output voltages. The output value s indicative of the thickness of the ice or ice and water mixture, or ice and other liquid.

  10. An eight-month sample of marine stratocumulus cloud fraction, albedo, and integrated liquid water

    NASA Technical Reports Server (NTRS)

    Fairall, C. W.; Hare, J. E.; Snider, J. B.

    1990-01-01

    Surface-meteorology and shortwave/longwave irradiance measurements taken on the northwest tip of San Nicolas Island off the coast of Southern California from March through October 1987 are analyzed. Experimental details are summarized, and shortwave cloud-radiation parameterization is outlined with emphasis on a shortwave algorithm. Frequency distributions indicate the stratocumulus clouds at the island have a cloud base on the order of 400 m, an integrated liquid water content of 75 g/sq m, and an albedo of 0.55 with substantial diurnal variations. The longwave parameterization for cloud fraction is also considered, and it is noted that using these models for downward longwave and shortwave irradiances, cloud fraction, integrated liquid water content, and albedo are deduced from the data.

  11. Intermediate range chemical ordering in amorphous and liquid water, Si, and Ge

    SciTech Connect

    Benmore, C.J.; Hart, R.T.; Mei, Q.; Price, D.L.; Yarger, J.; Tulk, C.A.; Klug, D.D.

    2005-10-01

    Neutron and x-ray diffraction data for low, high, and very high density amorphous ice and liquid water, silicon, and germanium have been compared in terms of the first sharp diffraction peak in the structure factor and at the radial distribution function level. The low and high density forms of H{sub 2}O, Si, and Ge are shown to have very similar structures if the contributions from the hydrogen correlations in water are neglected. The very high density amorphous ice form is shown to be structurally analogous to recently reported high pressure liquid forms of Si and Ge, although there are slight differences in the way interstitial atoms or molecules are pushed into the first coordination shell.

  12. Flow field distribution of liquid film of water lubricated bearing-rotor coupling systems

    NASA Astrophysics Data System (ADS)

    Hu, Q. L.; Hu, J. N.; Ye, X. Y.; Zhang, D. S.; Zheng, J. B.

    2016-05-01

    According to the desalination high-pressure pump water lubricated bearing-rotor coupling systems flow field distribution of liquid film in the starting transient process and its power transmission mechanism can lay the foundation of further exploring and judging lubrication state at the boot process. By using the computational fluid dynamics Fluent secondary development platform and calling the relevant DEFINE macro function to achieve the translation and rotation movement of the journal, we will use the dynamic grid technique to realize the automatic calculation and grid update of water lubricated bearings 3d unsteady liquid film flow field, and finally we will dispose the results of numerical simulation and get the pressure. When the eccentricity is large, film thickness was negatively correlated with the pressure, and positive with the velocity. Differential pressure was negatively correlated with velocity. When the eccentricity is small, film thickness is no significant relationship with differential pressure and velocity. Differential pressure has little difference with velocity.

  13. Low-Dimensional Water on Ru(0001)Model System for X-ray Absorption Spectroscopy Studies of Liquid Water

    SciTech Connect

    Nordlund, D

    2012-02-14

    We present an x-ray absorption spectroscopy resul