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1

Liquid polymorphism: water in nanoconfined and biological environments.  

PubMed

We demonstrate some recent progress in understanding the anomalous behavior of liquid water, by combining information provided by recent experiments and simulations on water in bulk, nanoconfined, and biological environments. We 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 as well as the unusual behavior of water in biological environments. Finally, we will discuss how the general concept of liquid polymorphism may prove 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. PMID:21399273

Stanley, H E; Buldyrev, S V; Franzese, G; Kumar, P; Mallamace, F; Mazza, M G; Stokely, K; Xu, L

2010-07-21

2

Cloud Liquid Water Measurements  

E-print Network

Liquid Water Content? Determines the Potential of Enhancing Precipitation using Cloud Seed TechniquesCloud Liquid Water Measurements By David Delene University of North Dakota #12;Why Measure Cloud (Mali, Saudi Arabia) Basic Cloud Parameter (MPACE) Icing Studies (WISP04, Sikorsky) Comparison

Delene, David J.

3

Water: The Strangest Liquid  

SciTech Connect

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.

Nilsson, Anders

2009-02-24

4

Dissolving Different Liquids in Water  

NSDL National Science Digital Library

In this activity, learners add different liquids to water and apply their working definition of âdissolvingâ to their observations. After observing isopropyl rubbing alcohol, vegetable oil, and corn syrup in water, learners can conclude that while some liquids may dissolve in water, different liquids dissolve in water to different extents. Adult supervision recommended.

Kessler, James H.; Galvan, Patricia M.

2007-01-01

5

Life's Little Essential: Liquid Water  

NSDL National Science Digital Library

Without liquid water, terrestrial life could not exist. All living organisms on Earth depend on water and its unique chemical and physical properties. In the search for life beyond Earth, scientists have focused their efforts on looking for signs of liquid water. This essay discusses the properties of liquid water that are conducive to life, pointing out that the biochemical reactions that sustain life need a fluid in order to operate, and that water is probably the best solvent in the universe.

2011-04-15

6

Liquid Assets: Sustainable Water Use  

NSDL National Science Digital Library

This video from a WPSU documentary Liquid Assets shows the transformation of Las Vegas’ water infrastructure. A desert community, Las Vegas is reducing water consumption and re-using wastewater, making optimal use of limited water resources.

Wpsu

2008-11-20

7

Liquid to quasicrystal transition in bilayer water.  

PubMed

The phase behavior of confined water is a topic of intense and current interest due to its relevance in biology, geology, and materials science. Nevertheless, little is known about the phases that water forms even when confined in the simplest geometries, such as water confined between parallel surfaces. Here we use molecular dynamics simulations to compute the phase diagram of two layers of water confined between parallel non hydrogen bonding walls. This study shows that the water bilayer forms a dodecagonal quasicrystal, as well as two previously unreported bilayer crystals, one tiled exclusively by pentagonal rings. Quasicrystals, structures with long-range order but without periodicity, have never before been reported for water. The dodecagonal quasicrystal is obtained from the bilayer liquid through a reversible first-order phase transition and has diffusivity intermediate between that of the bilayer liquid and ice phases. The water quasicrystal and the ice polymorphs based on pentagons are stabilized by compression of the bilayer and are not templated by the confining surfaces, which are smooth. This demonstrates that these novel phases are intrinsically favored in bilayer water and suggests that these structures could be relevant not only for confined water but also for the wetting and properties of water at interfaces. PMID:20969412

Johnston, Jessica C; Kastelowitz, Noah; Molinero, Valeria

2010-10-21

8

Liquid Assets: A Water System  

NSDL National Science Digital Library

This segment from a WPSU documentary Liquid Assets succinctly explains how water in New York journeys from its source to our faucets. Although water flows under our feet everyday, we are blissfully unaware of this service and take it for granted.

Wpsu

2008-11-20

9

Life's Little Essential: Liquid Water  

NSDL National Science Digital Library

Why is water necessary for life? Why is it the best and possibly only liquid to do the job? This illustrated essay from NOVA Online answers these questions, explaining why planetary scientists are on the lookout for water elsewhere in the solar system.

Foundation, Wgbh E.

2005-10-21

10

The physics of liquid water  

NASA Astrophysics Data System (ADS)

Water is a liquid with extraordinary properties: it has a very high cohesion, and an exceptionally strong dielectric cohesion, yet it is a fluid at ambient temperature and pressure. It also has an open structure that is full of voids, especially so at low temperatures. Some of these properties are found in other fluids, but the combination of all these anomalies makes liquid water unique among all other fluids. It is thanks to these unusual properties that life evolved in water and nowhere else. To cite this article: B. Cabane, R. Vuilleumier, C. R. Geoscience 337 (2005).

Cabane, Bernard; Vuilleumier, Rodolphe

2005-02-01

11

Static heterogeneities in liquid water  

NASA Astrophysics Data System (ADS)

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.

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

2004-10-01

12

Spontaneous liquid-liquid phase separation of water  

NASA Astrophysics Data System (ADS)

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.

Yagasaki, Takuma; Matsumoto, Masakazu; Tanaka, Hideki

2014-02-01

13

Liquid-Liquid Critical Point in Heavy Water  

Microsoft Academic Search

According to the liquid-liquid critical-point hypothesis about water, two liquid waters exist at low temperatures and are supposed to be merged at a critical point. The low-temperature metastable melting curves of D2O ices have been measured. It is found that the melting curve of D2O ice III is smoothly curved around 25 MPa and 238 K, whereas the melting curve

Osamu Mishima

2000-01-01

14

Geomorphologic evidence for liquid water  

USGS Publications Warehouse

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.

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

2001-01-01

15

Polymorphs  

E-print Network

? Lactose (anhydrous; also monohydrate) ? Aspartame (anhydrous; hydrate forms) ? Magnesium stearate (can affect lubrication of tablets) ? Triglycerides (?, ?, ?? forms) 26 Methods for study of polymorphism All of the phenomena mentioned could be used...

Prankerd, Richard

2006-10-26

16

Raman lidar observations of cloud liquid water.  

PubMed

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

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

2004-12-10

17

Dipolar correlations in liquid water.  

PubMed

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(3), but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (?) 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 ? 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. PMID:25173018

Zhang, Cui; Galli, Giulia

2014-08-28

18

Dipolar correlations in liquid water  

NASA Astrophysics Data System (ADS)

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/cm3, but it is substantially affected by the presence of solvated ions. In the same range of thermodynamic conditions, the decay time (?) 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 ? 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.

Zhang, Cui; Galli, Giulia

2014-08-01

19

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

NASA Astrophysics Data System (ADS)

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.

Mirgorod, Yu. A.

2014-08-01

20

Electrokinetic Power Generation from Liquid Water Microjets  

SciTech Connect

Although electrokinetic effects are not new, only recently have they been investigated for possible use in energy conversion devices. We have recently reported the electrokinetic generation of molecular hydrogen from rapidly flowing liquid water microjets [Duffin et al. JPCC 2007, 111, 12031]. Here, we describe the use of liquid water microjets for direct conversion of electrokinetic energy to electrical power. Previous studies of electrokinetic power production have reported low efficiencies ({approx}3%), limited by back conduction of ions at the surface and in the bulk liquid. Liquid microjets eliminate energy dissipation due to back conduction and, measuring only at the jet target, yield conversion efficiencies exceeding 10%.

Duffin, Andrew M.; Saykally, Richard J.

2008-02-15

21

Water as a solid, liquid, and gas  

NSDL National Science Digital Library

The representation is a set of 3 diagrams, with accompanying text explanations, showing the arrangement of water molecules in each of its three states of matter and an activity that uses BB's and petri dishes to create models of ice, liquid water, and water vapor.

22

Evidence for Liquid Water on Comets  

NASA Technical Reports Server (NTRS)

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.

Sheldon, Robert; Hoover, Richard

2005-01-01

23

Liquid Water Oceans in Ice Giants  

E-print Network

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. 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. 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 ~ 0.8 g/cm^3. Such a high density is inconsistent with gravitational data obtained during the Voyager flyby. As Neptune cools, the probability of a liquid ocean increases. Extrasolar "hot Neptunes," which presumably migrate inward toward their parent stars, cannot harbor liquid water oceans unless they have lost almost all of the hydrogen and helium from their deep interiors.

Sloane J. Wiktorowicz; Andrew P. Ingersoll

2006-09-26

24

II. Properties of Water 1. Ice and Liquid water structure  

E-print Network

II. Properties of Water 1. Ice and Liquid water structure 2. Cohesion / Surface Tension 3. High Heat Capacity 4. Solvent Properties 5. Dissociation: Acids & Bases / pH II. Organic Chemistry A producing molecules that are mirror images of one another that cannot be superimposed #12;Water As A Solvent

Frey, Terry

25

Liquid chromatographic determination of water  

DOEpatents

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.

Fortier, Nancy E. (Fairfield, OH); Fritz, James S. (Ames, IA)

1990-11-13

26

THz reflection spectroscopy of liquid water  

Microsoft Academic Search

We report an investigation of the temperature-dependent far-infrared spectrum of liquid water. We have employed a new experimental technique based on ultrashort electromagnetic pulses (THz pulses). This technique allows for fast and reliable data of both index of refraction and absorption coefficient for highly absorbing liquids. The temperature dependence reveals an enthalpy of activation corresponding to 2.5 kcal\\/mol, in agreement

L. Thrane; R. H. Jacobsen; P. Uhd Jepsen; S. R. Keiding

1995-01-01

27

Advancing into Water's "No Man's Land": Two Liquid States?  

PubMed

A tale of two liquids? Liquid water exhibits many anomalous properties which are strongly amplified in the supercooled state. A possible explanation for the unusual behavior is a phase transition between two distinct metastable forms of liquid water at deeply supercooled conditions. A recent theoretical study has confirmed the existence of this liquid-liquid phase transition. PMID:25252122

Paschek, Dietmar; Ludwig, Ralf

2014-10-27

28

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

NASA Astrophysics Data System (ADS)

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, TBmax 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 TBmax 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.

Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria

2014-11-01

29

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

PubMed

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, TB (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 TB (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. PMID:25399173

Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria

2014-11-14

30

Phase transitions of liquid water at nanoscale  

NASA Astrophysics Data System (ADS)

The behaviour of fluids confined within nanometric pores significantly differs from that of the bulk. The effect of confinement, surface forces, and reduced dimension is to shift the phase transitions of the confined fluid (condensation, freezing and crystallisation). By postponing or avoiding the inconvenient crystallization process it is often suggested that confinement allows a deeper penetration into the supercooled regime and helps in the understanding the glass formation; in the case of water, confinement might helps to extend the liquid state into the so-called ``no-man's land.'' However below confining conditions of about 10?, ? being the size of the molecule, water or van der Waals liquids are strongly perturbed by the presence of a surface. Thus a question always remains whether the confined liquid, water or any other fluid, is an extension of the ``bulk'' supercooled regime or refers to specific behavior controlled by external parameters such as the size and the surface interactions imposed to the system. Despite the obvious fundamental interest in understanding bulk water, this situation corresponds to most of the cases in biological and geological systems and deserves particular attention per se. However a prerequisite is to understand and quantify how pores are filled and how much; so we studied the processes of entrance and saturation to a pore (adsorption, imbibition and intrusion) in connection with the structure and the local dynamics of liquid water. Then, we will present new experimental results on the thermodynamic, structural and vibrational properties of water confined within nanometric pores (size of a few molecular diameters).

Alba-Simionesco, Christiane

2013-03-01

31

Theory of water and charged liquid bridges  

E-print Network

The phenomena of liquid bridge formation due to an applied electric field is investigated. A new solution for the charged catenary is presented which allows 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 is 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.

Klaus Morawetz

2011-07-03

32

Recent Images Suggesting Liquid Water on Mars  

NSDL National Science Digital Library

Recently, the press reported that the Mars Orbiter Camera (MOC) had captured compelling images of gullies and slope failures that might be associated with the presence of liquid water on Mars. Now you can see these famous images at Malin Space Science Systems' MOC Website. These sharp, beautiful, color images (.jpeg, .gif) are featured on pages containing descriptions of how such physical features are formed on earth. The images are available in two sizes (small = 360K, large = 690K). Highlights include the "gully landform" compared to channel and apron features on Mount Saint Helens on Earth, a 3-D image (3-D glasses required) of a "weeping" alcove in an impact crater, and clues suggesting that the suspected liquid water on Mars is relatively young.

33

Dispersion corrected RPBE studies of liquid water.  

PubMed

The structure of liquid water has been addressed by ab initio molecular dynamics simulations based on density functional theory. Exchange-correlation effects have been described by the popular PBE and RPBE functionals within the generalized gradient approximation as these functionals also yield satisfactory results for metals which is important to model electrochemical interfaces from first principles. In addition, dispersive interactions are included by using dispersion-corrected schemes. It turns out that the dispersion-corrected RPBE functional reproduces liquid water properties quite well in contrast to the PBE functional. This is caused by the replacement of the over-estimated directional hydrogen-bonding in the PBE functional by non-directional dispersive interactions. PMID:25134582

Forster-Tonigold, Katrin; Groß, Axel

2014-08-14

34

Performance of Water-based Liquid Scintillator  

NASA Astrophysics Data System (ADS)

Water-based detectors can only see the Cherenkov light from the fast moving charged particles, thus missing all the particles below the Cherenkov threshold. Detecting these below-threshold particles is important for various applications like the mobile detectors for the nuclear reactor monitoring, the search of the proton decay, and reconstruction of the neutrino energy and the reaction type by observing the vertex activity for both long and short baseline experiments. This detection can be achieved by using the Water-based Liquid Scintillator (WbLS), currently under development. It is based on the idea of dissolving the organic scintillator in water using special surfactants. This new material strives to achieve the novel detection techniques by combining the Cherenkov rings and scintillation light, as well as the total cost reduction compared to pure liquid scintillator (LS). We will present light yield measurements for the proton beam energies of 210MeV, 475MeV and 2000MeV for water, two different WbLS formulations (1% and 4%) and pure LS. These beam energies were chosen to study the contribution of the Cherenkov light to the total output.

Beznosko, Dmitriy

2013-04-01

35

Liquid-liquid equilibrium of cholinium-derived bistriflimide ionic liquids with water and octanol.  

PubMed

The liquid-liquid equilibria of mixtures of cholinum-based ionic liquids (N-alkyl-N,N-dimethylhydroxyethylammonium bis(trifluoromethane)sulfonylimide, [N(11n2OH)][Ntf(2)], n = 1, 2, 3, 4, and 5) plus water or 1-octanol were investigated at atmospheric pressure over the entire composition range. The experiments were conducted between 265 and 385 K using the cloud-point method. The systems exhibit phase diagrams consistent with the existence of upper critical solution temperatures. The solubility of [N(1 1 n 2OH)][Ntf(2)] in water is lower for cations with longer alkyl side chains (larger n values). The corresponding trend in the octanol mixtures is reversed. The ([N(1 1 1 2OH)][Ntf(2)] + water + octanol) ternary system shows triple liquid-liquid immiscibility at room temperature and atmospheric pressure. A combined analytic/synthetic method was used to estimate the corresponding phase diagram under those conditions. Auxiliary molecular dynamics simulation data were used to interpret the experimental results at a molecular level. PMID:22770438

Costa, Anabela J L; Soromenho, Mário R C; Shimizu, Karina; Marrucho, Isabel M; Esperança, José M S S; Canongia Lopes, J N; Rebelo, Luís Paulo N

2012-08-01

36

Metastable liquid-liquid transition in a molecular model of water  

NASA Astrophysics Data System (ADS)

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 the ST2 model of water, and point to the separation of time scales between crystallization and relaxation as being crucial for enabling it.

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

2014-06-01

37

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

PubMed

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 the ST2 model of water, and point to the separation of time scales between crystallization and relaxation as being crucial for enabling it. PMID:24943954

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

2014-06-19

38

Triplet correlation functions in liquid water.  

PubMed

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. PMID:25381528

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

2014-11-01

39

Interaction and permeability of water with liquid crystalline thermoset  

Microsoft Academic Search

The complex transport behavior of water in both liquid crystalline thermoset and non-liquid crystalline thermoset systems were investigated. The liquid crystalline thermoset was 4,4'-diglycidyloxy-alpha-methylstilbene with sulfanilamine (SAA) as the crosslinking agent, the non-liquid crystalline thermoset the diglycidyl ether of bisphenol A. The liquid crystalline thermosets have higher barrier properties than isotropic non-LC epoxy resins. The efficient chain packing of the

Jianxun Feng

2001-01-01

40

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

SciTech Connect

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.

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

1999-12-01

41

Evidence for Recent Liquid Water on Mars  

NASA Technical Reports Server (NTRS)

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. The Mars Orbiter Camera (MOC) high resolution view is located near 41.1S, 159.8W and is a mosaic of three different pictures acquired between January and May 2000. The MOC scene is illuminated from the left; north is up.

2000-01-01

42

Sound propagation in liquid water: The puzzle continues Francesco Sciortino  

E-print Network

; accepted 16 November 1993) Experimental and simulation studies of sound propagation in water have observedSound propagation in liquid water: The puzzle continues Francesco Sciortino CRS4, Centro di Ricerca. INTRODUCTION The propagation of the sound in liquid water has re- ceived a lot of attention in recent years

Sciortino, Francesco

43

Hydrogen bonds in liquid water are broken only fleetingly  

E-print Network

Hydrogen bonds in liquid water are broken only fleetingly J. D. Eaves* , J. J. Loparo* , C. J that the local structure of liquid water has tetrahedral arrangements of molecules ordered by hydrogen bonds, the mechanism by which water molecules switch hydrogen-bonded partners remains unclear. In this mechanism

Geissler, Phillip

44

Relaxations, Fluctuations, Phase Transitions and Chemical Reactions in Liquid Water  

Microsoft Academic Search

Fluctuations and collective motions in liquid water and their effects on chemical reactions dynamics are analyzed. Liquid water is a `frustrated' system with multiple random hydrogen bond network structures, and has anomalous microscopic and macroscopic properties. Rearrangement dynamics of the hydrogen bond network induces collective motions of water molecules and energy fluctuations. Vibrational motions of photoexcited molecules strongly resonate to

Iwao Ohmine; Masaki Sasai

1991-01-01

45

The physics of liquid water Bernard Cabane1  

E-print Network

. There is also a large amount of water (equivalent to one ocean) that is dissolved in the earth's "mantle". Water the following questions: - Why is water a liquid at ambient temperature and pressure, rather than a gas the oxygen atom [1]. Figure 1 Melting and boiling temperatures of the homologous liquids H2O, H2S, H2Se and H

Paris-Sud XI, Université de

46

Routine Use of PCR-Restriction Fragment Length Polymorphism Analysis for Identification of Mycobacteria Growing in Liquid Media  

Microsoft Academic Search

A PCR-restriction fragment length polymorphism (PCR-RFLP) procedure capable of rapidly identifying 28 species of clinically encountered mycobacteria was evaluated for use in the routine identification of acid-fast isolates growing in BACTEC 12B and 13A liquid media. PCR-RFLP identified 100 of 103 acid-fast isolates recovered from 610 patient specimens submitted for culture during the study. The three isolates unidentifiable by PCR-RFLP

THERESA B. TAYLOR; CANDY PATTERSON; YVONNE HALE; ANDWILLIAM W. SAFRANEK

1997-01-01

47

Water-only chemical analysis methodologies: investigations of water liquid chromatography, subcritical water extracton, and dynamic surface tension detection.  

E-print Network

??Investigations into methods for performing chemical analysis using a solvent exclusively of water are demonstrated in the areas of liquid chromatography, solid-liquid extraction, and dynamic… (more)

Young, Toby Edward, 1970-

1998-01-01

48

Displacement of nonwetting liquids from unsaturated sands by water infiltration  

SciTech Connect

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.

Boley, T.M. [Huntsman Chemical Corp., Peru, IL (United States); Overcamp, T.J. [Clemson Univ., Anderson, SC (United States). Dept. of Environmental Engineering and Science

1998-09-01

49

Water Percolation Governs Polymorphic Transitions and Conductivity of DNA  

NASA Astrophysics Data System (ADS)

We report on the first computer simulation studies of the percolation transition of water at the surface of the DNA double helix. With increased hydration, the ensemble of small clusters merges into a spanning water network via a quasi-two-dimensional percolation transition. This transition occurs strikingly close to the hydration level where the B form of DNA becomes stable in experiment. Formation of spanning water networks results in sigmoidlike acceleration of long-range ion transport in good agreement with experiment.

Brovchenko, Ivan; Krukau, Aliaksei; Oleinikova, Alla; Mazur, Alexey K.

2006-09-01

50

Water Percolation Governs Polymorphic Transitions and Conductivity of DNA  

Microsoft Academic Search

We report on the first computer simulation studies of the percolation transition of water at the surface of the DNA double helix. With increased hydration, the ensemble of small clusters merges into a spanning water network via a quasi-two-dimensional percolation transition. This transition occurs strikingly close to the hydration level where the B form of DNA becomes stable in experiment.

Ivan Brovchenko; Aliaksei Krukau; Alla Oleinikova; Alexey K. Mazur

2006-01-01

51

Autoionization in Liquid Water Phillip L. Geissler,1  

E-print Network

¨rg Hutter,3 Michele Parrinello3 The dissociation of a water molecule in liquid water is the fundamental- tectable signal of the dynamics we report. A randomly chosen, intact water molecule will dissociate, they imag- ined that dissociation of a water molecule is driven by rearrangement of solvating water

Dellago, Christoph

52

liquid water path estimates in marine stratus 1.Introduction  

E-print Network

liquid water path estimates in marine stratus P.Zuidema 1.Introduction Marine boundary-layer liquid establish the extent of non-adiabatic cloud processes. In addition,a comparison of surface-based microwave,both liquid and dry. To date,the impact of microwave model improvements upon LWPs retrieved within marine

Zuidema, Paquita

53

Evidence for liquid water during the high-density to low-density amorphous ice transition  

PubMed Central

Polymorphism of water has been extensively studied, but controversy still exists over the phase transition between high-density amorphous (HDA) and low-density amorphous (LDA) ice. We report the phase behavior of HDA ice inside high-pressure cryocooled protein crystals. Using X-ray diffraction, we demonstrate that the intermediate states in the temperature range from 80 to 170 K can be reconstructed as a linear combination of HDA and LDA ice, suggesting a first-order transition. We found evidence for a liquid state of water during the ice transition based on the protein crystallographic data. These observations open the possibility that the HDA ice induced by high-pressure cryocooling is a genuine glassy form of high-density liquid. PMID:19258453

Kim, Chae Un; Barstow, Buz; Tate, Mark W.; Gruner, Sol M.

2009-01-01

54

A conjecture concerning collective excitations in liquid water  

NASA Astrophysics Data System (ADS)

We show that the distribution of rings of water molecules in a molecular dynamics simulation of liquid water is consistent with the hypothesis that there are collective coordinates that convert 6-rings to n-rings.

Rice, Stuart A.; Belch, Alan C.; Sceats, Mark G.

1981-12-01

55

On the polymorphism of a sapogenin monohydrate induced by different rotations of water molecules.  

PubMed

The structure of 1beta,3beta,11alpha-trihydroxyspirosta-5,25(27)-diene (C(27)H(40)O(5); a steroidal sapogenin) isolated from Helleborus serbicus Adam 1906 (Ranunculaceae) and crystallized from absolute ethanol as a monohydrate (melting point 519-522 K) had been characterized by two symmetry-independent binary (steroid-water) layers, cross-linked by hydrogen bonds [Kálmán et al. (1985). Acta Cryst. C41, 1645-1647]. Recently, a novel monohydrate was crystallized again from absolute ethanol (source: Helleborus multifidus subspecies serbicus) with a somewhat higher melting point of 525-526 K. X-ray analysis of these crystals [Argay et al. (1998). Acta Chim. Hung. 135, 449-456] revealed a novel polymorph (hereinafter denoted polymorph B), which is also built up by two binary layers of C(27)H(40)O(5) and H(2)O, but in which the relative position of these layers differs from that found in the first modification (polymorph A). Comparing the two polymorphs, layers of one type are found to be similar, displaying identical hydrogen bonding, whereas layers of the second type differ with respect to the orientations adopted by the water molecules; these orientations also differ from those in the layers of the first type. Consequently, by these water rotations, hydrogen bonds, at least partly, are reversed. This leads to two different close packings: in form A four consecutive layers are cross-linked by two homomolecular (hydroxyl.hydroxyl and water.water) hydrogen-bond pairs, while in B there are only heteromolecular hydroxyl.water bonds. These hydrogen-bond dissimilarities together with the differences in the weak CH.X etc. interactions explain the greater stability of the higher melting-point form B. PMID:10927418

Fábián; Argay; Kálmán

1999-10-01

56

Liquid-liquid equilibria of fuel oxygenate + water + hydrocarbon mixtures. 3: Effect of temperature  

SciTech Connect

The authors have measured the ternary liquid-liquid equilibria of water + ethanol mixtures with, separately, 2,2,4-trimethylpentane and toluene at 5 and 40 C, water + tert-amyl alcohol (TAOH) mixtures with, separately, toluene and hexane at 5 and 40 C, and of water + TAOH + pentane mixtures at 5 C. The ethanol-containing systems exhibit type 1 liquid-liquid phase behavior, and the TAOH-containing systems exhibit type 2 behavior. These data, together with the data they have previously reported at 25 C, provide information on how the liquid-liquid equilibria of these systems change as a function of temperature. While the addition of ethanol is found to increase the solubility of hydrocarbons in the aqueous phase, the concentration of the hydrocarbon in the water-rich phase decreases with increasing temperature. With the exception of hydrocarbon in the water-rich phase, the experimental data could be correlated quite well with either the UNIQUAC or NRTL models. For most of the systems considered here the predictions of the phase behavior with the liquid-liquid UNIFAC group-contribution model are only qualitatively correct. However, the liquid-liquid UNIFAC model erroneously predicts type 2 phase behavior to occur for water + ethanol + 2,2,4-trimethylpentane system at 5 C.

Wagner, G. [Universitaet Karlsruhe (Germany). Institut fuer Thermische Verfahrenstechnik; Sandler, S.I. [Univ. of Delaware, Newark, DE (United States). Center for Molecular and Engineering Thermodynamics

1995-09-01

57

Rapid determination of 226 Ra in drinking water samples using dispersive liquid-liquid microextraction coupled with liquid scintillation counting  

Microsoft Academic Search

A new radioanalytical method was developed for rapid determination of 226Ra in drinking water samples. The method is based on extraction and preconcentration of 226Ra from a water sample to an organic solvent using a dispersive liquid-liquid microextraction (DLLME) technique followed by\\u000a radiometric measurement using liquid scintillation counting. In DLLME for 226Ra, a mixture of an organic extractant (toluene doped

Baki B. Sadi; Chunsheng Li; Gary H. Kramer; Cassandra L. Johnson; Queenie Ko; Edward P. C. Lai

58

The Putative Liquid-Liquid Transition is a Liquid-Solid Transition in Atomistic Models of Water  

E-print Network

We use numerical simulation to examine the possibility of a reversible liquid-liquid transition in supercooled water and related systems. In particular, for two atomistic models of water, we have computed free energies as functions of multiple order parameters, where one is density and another distinguishes crystal from liquid. For a range of temperatures and pressures, separate free energy basins for liquid and crystal are found, conditions of phase coexistence between these phases are demonstrated, and time scales for equilibration are determined. We find that at no range of temperatures and pressures is there more than a single liquid basin, even at conditions where amorphous behavior is unstable with respect to the crystal. We find a similar result for a related model of silicon. This result excludes the possibility of the proposed liquid-liquid critical point for the models we have studied. Further, we argue that behaviors others have attributed to a liquid-liquid transition in water and related systems are in fact reflections of transitions between liquid and crystal.

David T. Limmer; David Chandler

2011-07-01

59

Thermoluminescence dosimetry measurements of brachytherapy sources in liquid water  

SciTech Connect

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.

Tailor, Ramesh; Tolani, Naresh; Ibbott, Geoffrey S. [Radiation Physics, UT M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Unit 94, Houston, Texas 77030 (United States); Radiological Physics Center, UT M.D. Anderson Cancer Center, 7515 South Main Street, Suite 300, Houston, Texas 77030-4519 (United States)

2008-09-15

60

Ultrafast phase transitions in metastable water near liquid interfaces.  

PubMed

Electron spectroscopy for chemical analysis (ESCA) is a powerful tool for the quantitative analysis of the composition and the chemical environment of molecular systems. Due to the lack of compatibility of liquids and vacuum, liquid-phase ESCA is much less well established. The chemical shift in the static ESCA approach is a particularly powerful observable quantity for probing electron orbital energies in molecules in different molecular environments. Employing high harmonics of 800 nm (40 eV), near-infrared femtosecond pulses, and liquid-water microbeams in vacuum we were able to add the dimension of time to the liquid interface ESCA technique. Tracing time-dependent chemical shifts and energies of valence electrons in liquid interfacial water in time, we have investigated the timescale and molecular signatures of laser-induced liquid-gas phase transitions on a picosecond timescale. PMID:19227352

Link, Oliver; Vöhringer-Martinez, Esteban; Lugovoj, Eugen; Liu, Yaxing; Siefermann, Katrin; Faubel, Manfred; Grubmüller, Helmut; Gerber, R Benny; Miller, Yifat; Abel, Bernd

2009-01-01

61

Glass–liquid transition of water at high pressure  

PubMed Central

The knowledge of the existence of liquid water under extreme conditions and its concomitant properties are important in many fields of science. Glassy water has previously been prepared by hyperquenching micron-sized droplets of liquid water and vapor deposition on a cold substrate (ASW), and its transformation to an ultraviscous liquid form has been reported on heating. A densified amorphous solid form of water, high-density amorphous ice (HDA), has also been made by collapsing the structure of ice at pressures above 1 GPa and temperatures below approximately 140 K, but a corresponding liquid phase has not been detected. Here we report results of heat capacity Cp and thermal conductivity, in situ, measurements, which are consistent with a reversible transition from annealed HDA to ultraviscous high-density liquid water at 1 GPa and 140 K. On heating of HDA, the Cp increases abruptly by (3.4 ± 0.2) J mol-1 K-1 before crystallization starts at (153 ± 1) K. This is larger than the Cp rise at the glass to liquid transition of annealed ASW at 1 atm, which suggests the existence of liquid water under these extreme conditions. PMID:21690361

Andersson, Ove

2011-01-01

62

Three Different Behaviors of Liquid Water Path of Water Clouds in Aerosol-Cloud Interactions  

E-print Network

Three Different Behaviors of Liquid Water Path of Water Clouds in Aerosol-Cloud Interactions Huntsville, AL 2 NASA/Goddard Institute for Space Studies New York, NY Abstract Estimates of the indirect aerosol effect in GCMs assume either that cloud liquid water path is constant (Twomey effect) or increases

Han, Quingyuan

63

Liquid water in the extremely shallow Martian subsurface  

NASA Astrophysics Data System (ADS)

The discovery of a near-surface ice layer on Mars by the Phoenix lander has led to speculation about the stability of water in the subsurface, as the availability of liquid water is a major constraint for a potential Martian biosphere. Liquid water is unstable on the surface of Mars due to low atmospheric pressures, but it has been suggested that liquid water might be present as films or adsorbed layers in the regolith. This study was carried out to assess the stability of permafrost and liquid water in the Martian subsurface, and to support the interpretation of conductivity data from the Phoenix mission. Using a new Goddard Martian simulation chamber, we explored the possibility of liquid water formation in the extremely shallow (1-3 cm) subsurface soil layer under low atmospheric pressures (0.1-10 mbar) and analogous Martian surface temperatures (~ -50 C to 0 C). This was achieved through the use of impedance spectroscopy with conductivity probes similar to those used by Phoenix. Our results demonstrate that in a shallow layer of clean permafrost the amount of mobile liquid water present as films can reach several percent, even with temperatures as low as -25 C. The presence of perchlorates, found in the Martian regolith, causes the formation and mobility of liquid water to increase dramatically due to the effects of perchlorates on the melting temperature of ice. This study suggests that despite cold temperatures and low atmospheric pressures, the Martian regolith may contain appreciable amounts of liquid water in the near subsurface. Permafrost on Mars can be expected to extend to some depth, particularly in polar latitudes. These findings have implications for aqueous processing on Mars and the habitability of the Martian subsurface throughout its history.

Shivak, J. N.; Pavlov, A.

2012-12-01

64

Liquid water in the domain of cubic crystalline ice Ic.  

PubMed

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. PMID:11542399

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

1997-07-22

65

Experimentally proven liquid-liquid critical point of dilute glycerol-water solution at 150 K  

NASA Astrophysics Data System (ADS)

The experimental and theoretical studies of supercooled liquid water strongly suggest that the two liquid waters and their liquid-liquid critical point (LLCP) exist at low temperature. However, the decisive experimental evidence of the LLCP has not been obtained because of the rapid crystallization of liquid water in the "no-man's land." Here, we observed experimentally the pressure-induced polyamorphic transition in the dilute glycerol-water solution which relates to the water polyamorphism. We examined the effect of the glycerol concentration on the liquid-liquid transition, and found its LLCP around 0.12-0.15 mole fraction, 0.03-0.05 GPa, and ˜150 K. A 150 K was above, or around, the recently recognized glass transition temperatures of amorphous ices, and the crystallization did not occur, indicating that the direct observation of LLCP is feasible. The low-temperature LLCP has implication to the argument of the relation between the interaction potential of water molecule and the polyamorphic phase diagram.

Suzuki, Yoshiharu; Mishima, Osamu

2014-09-01

66

Liquid–liquid transition in supercooled water suggested by microsecond simulations  

PubMed Central

The putative liquid–liquid phase transition in supercooled water has been used to explain many anomalous behaviors of water. However, no direct experimental verification of such a phase transition has been accomplished, and theoretical studies from different simulations contradict each other. We investigated the putative liquid–liquid phase transition using the Water potential from Adaptive Force Matching for Ice and Liquid (WAIL). The simulation reveals a first-order phase transition in the supercooled regime with the critical point at ?207 K and 50 MPa. Normal water is high-density liquid (HDL). Low-density liquid (LDL) emerges at lower temperatures. The LDL phase has a density only slightly larger than that of the ice-Ih and shows more long-range order than HDL. However, the transformation from LDL to HDL is spontaneous across the first-order phase transition line, suggesting the LDL configuration is not poorly formed nanocrystalline ice. It has been demonstrated in the past that the WAIL potential provides reliable predictions of water properties such as melting temperature and temperature of maximum density. Compared with other simple water potentials, WAIL is not biased by fitting to experimental properties, and simulation with this potential reflects the prediction of a high-quality first-principle potential energy surface. PMID:23836647

Li, Yaping; Li, Jicun; Wang, Feng

2013-01-01

67

Spectroscopic investigations of hydrogen bond dynamics in liquid water  

E-print Network

Many of the remarkable physical and chemical properties of liquid water are due to the strong influence hydrogen bonds have on its microscopic dynamics. However, because of the fast timescales involved, there are relatively ...

Fecko, Christopher J., 1975-

2004-01-01

68

Determination of liquid water altitudes using combined remote sensors  

SciTech Connect

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.

Politovich, M.K. [National Center for Atmospheric Research, Boulder, CO (United States)] [National Center for Atmospheric Research, Boulder, CO (United States)

1995-09-01

69

Evidence for Recent Liquid Water on Mars  

NASA Technical Reports Server (NTRS)

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 martian color. It is likely Mars would not look like this to a human observer at Mars.

2000-01-01

70

Glass Transition in Biomolecules and the Liquid-Liquid Critical Point of Water Pradeep Kumar,1  

E-print Network

, sometimes called a ``protein glass transition,'' occurs at the temperature of dynamic crossoverGlass Transition in Biomolecules and the Liquid-Liquid Critical Point of Water Pradeep Kumar,1 Z and the temperature derivative of the orientational order parameter. We relate these findings to the hypothesis

Stanley, H. Eugene

71

Water: The Liquid of Life. Fifth Grade.  

ERIC Educational Resources Information Center

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…

Illinois State Environmental Protection Agency, Springfield.

72

Process for blending coal with water immiscible liquid  

DOEpatents

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.

Heavin, Leonard J. (Olympia, WA); King, Edward E. (Gig Harbor, WA); Milliron, Dennis L. (Lacey, WA)

1982-10-26

73

Ice-Crystal Fallstreaks from Supercooled Liquid Water Parent Clouds  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

74

Liquid Water in the Extremely Shallow Martian Subsurface  

NASA Technical Reports Server (NTRS)

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.

Pavlov, A.; Shivak, J. N.

2012-01-01

75

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

PubMed

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 ? ?-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 ?-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

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

76

Nanoscale Dynamics of Phase Flipping in Water near its Hypothesized Liquid-Liquid Critical Point  

PubMed Central

One hypothesized explanation for water's anomalies imagines the existence of a liquid-liquid (LL) phase transition line separating two liquid phases and terminating at a LL critical point. We simulate the classic ST2 model of water for times up to 1000?ns and system size up to N = 729. We find that for state points near the LL transition line, the entire system flips rapidly between liquid states of high and low density. Our finite-size scaling analysis accurately locates both the LL transition line and its associated LL critical point. We test the stability of the two liquids with respect to the crystal and find that of the 350 systems simulated, only 3 of them crystallize and these 3 for the relatively small system size N = 343 while for all other simulations the incipient crystallites vanish on a time scales smaller than ? 100?ns. PMID:22761987

Kesselring, T. A.; Franzese, G.; Buldyrev, S. V.; Herrmann, H. J.; Stanley, H. E.

2012-01-01

77

Behavior of Supercooled Aqueous Solutions Stemming from Hidden Liquid-Liquid Transition in Water  

E-print Network

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, to be consistent with the presence of the metastable liquid-liquid transition. We suggest an interpretation of the liquid-liquid transition in aqueous solutions of glycerol, recently observed by Murata and Tanaka, elucidating the non-conserved nature of the order parameter, its coupling with density and concentration, and the peculiarity of "spinodal decomposition without phase separation". We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

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

2014-04-09

78

Solid-liquid phase diagrams for the determination of the solid state nature of both polymorphs of (RS)-2-(2-oxo-pyrrolidin-1-yl)-butyramide.  

PubMed

This work focuses on the determination of the solid state nature of (RS)-2-(2-oxo-pyrrolidin-1-yl)-butyramide (Etiracetam), the racemic intermediate of (S)-2-(2-oxo-pyrrolidin-1-yl)-butyramide, an Active Pharmaceutical Ingredient, marketed under the name Levetiracetam(®). It is show how this information can easily be extracted from solid-liquid phase diagrams of the racemic system. As two polymorphs of Etiracetam are known (Forms I and II), the analyses have been performed considering both polymorphs. The solid-liquid phase diagrams are determined experimentally, using Differential Scanning Calorimetry, and theoretically, using the Prigogine-Defay and Schroeder-Van Laar equations. Only the phase diagram involving the polymorph stable at higher temperatures (Form II) can be constructed experimentally. The theoretical phase diagram involving this polymorph compares well with the experimental one, thus allowing the use of theoretical equations for the prediction of the solid-liquid phase diagram involving Form I, which is meta-stable above 30.5 °C. Our findings confirm that both polymorphs are racemic compounds, which is also confirmed by XRPD analysis. PMID:22846407

Herman, Christelle; Haut, Benoît; Aerts, Luc; Leyssens, Tom

2012-11-01

79

Distributed Reforming of Renewable Liquids via Water Splitting using  

E-print Network

Distributed Reforming of Renewable Liquids via Water Splitting using Oxygen Transport Membrane (OTM-throughput manufacturing methods ­ Compact design reduces construction costs C ­ Operation & maintenance costs ­ Uses Spring Al2O3 Rod seal Al2O3 Tubes Agilent 6890 GC Column: molecular sieve 5A Detector: TCD Water Trap

80

Three Different Behaviors of Liquid Water Path of Water Clouds in Aerosol-Cloud Interactions  

Microsoft Academic Search

Estimates of the indirect aerosol effect in GCMs assume that either cloud liquid water path is constant (Twomey effect) or increases with increased droplet number concentration (drizzle-suppression or Albrecht effect). On the other hand, if cloud thermodynamics and dynamics are considered, cloud liquid water path may also decrease with increasing droplet number concentration, which has been predicted by model calculations

Qingyuan Han; William B. Rossow; Jian Zeng; Ronald Welch

2002-01-01

81

Interaction of C1O radical with liquid water  

SciTech Connect

In the present work, the interaction between ClO radical and liquid water is studied using molecular dynamics simulations. We perform simulations of collisions of a ClO radical with the surface of liquid water to understand the accommodation of ClO by liquid water. Simulations results show that the ClO radical has a higher propensity to be adsorbed on the air-water interface than be dissolved in the bulk. The free energy profile is also calculated and the solvation free energy and Henry’s law constant is determined for ClO as, ?Gs, of -2.9 kcal/mol and 5.5 M/atm, respectively. The mechanism of the ClO recombination reaction is also discussed and the results are consistent with laboratory findings.

Du, Shiyu; Francisco, Joseph S.; Schenter, Gregory K.; Garrett, Bruce C.

2009-10-21

82

Searching for liquid water in Europa by using surface observatories.  

PubMed

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

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

2002-01-01

83

The Putative Liquid-Liquid Transition is a Liquid-Solid Transition in Atomistic Models of Water, Part II  

E-print Network

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 [J. Chem. Phys. 135, 134503 (2011) and arXiv:1107.0337v2]. Low-temperature reversible free energy surfaces of several different atomistic models are computed: mW water, TIP4P/2005 water, SW 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 u...

Limmer, David T

2013-01-01

84

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

PubMed

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

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

2014-06-01

85

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

86

Vapor-liquid equilibrium of amine-water systems  

E-print Network

extraction method for saline water conversion. The investigation of vapor-liquid equilibrium relationships of the solutions of amine and water is an important step towards correlating the effect of molecular structure on the thermodynamic properties... of the interesting properties of water solutions of methyldiethyl amine and other tertiary amines . The work presented here involves the construction of an experi- mental apparatus, and presentation of data determined using that appara- tus for the system of 5...

Chun, Kil Whan

2012-06-07

87

Ion transport through a water-organic solvent liquid-liquid interface: a simulation study.  

PubMed

Ion interactions and partitioning at the water-organic solvent interface and the solvation characteristics have been characterized by molecular dynamics simulations. More precisely, we study sodium cation transport through water-cyclohexane, water-1,2-dichloroethane, and water-pentanol interfaces, providing a systematic characterization of the ion interfacial behavior including barriers against entering the organic phase as well as characterization of the interfaces in the presence of the ions. We find a sodium depletion zone at the liquid-liquid interface and persistent hydration of the cation when entering the organic phase. The barrier against the cation entering the organic phase and ion hydration depend strongly on specific characteristics of the organic solvent. The strength of both barrier and hydration shell binding (persistence of the cation hydration) go with the polarity and the surface tension at the interface, that is, both decrease in order cyclohexane-water > 1,2-dichloroethane-water > pentanol-water. However, the size of the hydration shell measured in water molecules bound by the cation entering the less polar phase behaves oppositely, with the cation carrying most water to the pentanol phase and a much smaller in size, but very tightly bound water shell to cyclohexane. We discuss the implications of the observations for ion transport through the interface of immiscible or poorly miscible liquids and for materials of confined ion transport such as ion conduction membranes or biological ion channel activity. PMID:24814815

Holmberg, Nico; Sammalkorpi, Maria; Laasonen, Kari

2014-06-01

88

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

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

Tanaka, Hajime

2012-10-01

89

How much liquid water was there on Martian dunes?  

NASA Astrophysics Data System (ADS)

Presently, liquid water unlikely to be found on the surface of Mars because of atmospheric pressure/temperature conditions below water's triple-point. However, gullies discovered by Malin and Edgett (2000) suggest that significant amounts of liquid water has flowed on Mars in the recent past. These gullies are among the youngest features on Mars based on the scarcity of cratered gullies (Heldmann et al., 2007) and their superposition on relatively young formations such as dunes. Several hypotheses have been suggested for the formation of gullies: (i) runoff and debris flows with liquid water from groundwater aquifers (Heldmann and Mellon, 2004; Malin et al., 2000), (ii) snow-melt (Christensen, 2003; Dickson et al, 2007), (iii) liquid CO2 breakout (Musselwhite et al., 2001), (iv) melting of near-surface ground ice (< 1 m meter) at high obliquity (Costard et al., 2002), (v) geothermal-heated aquifers (Gaidos, 2001; Hartmann, 2001), (vi) the presence of brines (Knauth et al., 2000; Knauth and Burt, 2003). This study focuses on gully morphologies on the Russell megadune (54.5°S; 12.7°E) and in Kaiser crater (46.2°S; 19.1°E) using High Resolution Imaging Science Experiment (HiRISE) images and Digital Terrain Models (DTM). Gullies on terrestrial sand dunes are rare, and their presence on Mars, as well as their mechanical properties, and the quantity of fluid required for their formation currently remain misunderstood. Based on the scenario of ground ice melting in a periglacial environment, we propose to test the hypothesis that Martian gullies on dunes were triggered by the presence of liquid water. The calculated results for Martian gullies are consistent with terrestrial studies on debris flows. Based on a morphological description and on the estimated physical parameters, we propose a model for gully formation on Martian dunes. The melt water from near-surface ground ice is incorporated in the debris flow and water concentration increases during its propagation. The increase of water concentration in the debris flow can be explained by a progressive increase of water/ice content in the permafrost downslope. Consequently, the lack of a final deposit at the front of some gullies tends to demonstrate that the flow became relatively highly concentrated in liquid downstream and all the water could have been lost in the final stage of the flow. Here we quantify the quantity of liquid necessary to form such a morphology.

Gargani, J.; Jouannic, G.; Costard, F.; Ori, G. G.; Marmo, C.; Schmidt, F.; Lucas, A.; Busson, J.

2012-04-01

90

Dispersive liquid–liquid microextraction based on ionic liquid in combination with high-performance liquid chromatography for the determination of bisphenol A in water  

Microsoft Academic Search

A method termed dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography-variable wavelength detection (HPLC-VWD) was developed. DLLME-HPLC-VWD is a method for determination of bisphenol A (BPA) in water samples. In this microextraction method, several parameters such as extraction solvent volume, sample volume, disperser solvent, ionic strength, pH, and disperser volume were optimised with the aid of interactive orthogonal array

Yu Li; Jianlin Liu

2010-01-01

91

Assessing Approaches for Determination of Liquid Water in Snow  

NASA Astrophysics Data System (ADS)

Scientists with expertise in avalanche formation, remote sensing issues, and other cryospheric matters gathered in Davos, Switzerland, in early April for a workshop on liquid water in snow—the first such meeting since 1982. The focus of this year's workshop, held at the Institute for Snow and Avalanche Research, was to compare different measurement techniques and their accuracy, to discuss current assumptions for modeling liquid water transport and storage in snow, and to gather ideas on how to best obtain good validation and verification data.

Eisen, Olaf; Schweizer, Jürg

2014-09-01

92

Isobaric vapor-liquid equilibrium for ethanol + water + potassium nitrate  

SciTech Connect

An increasing research interest in the determination of the salt effect in the vapor-liquid equilibrium of binary systems has developed over the last few decades due to the importance of distillation with salts in the separation of close boiling and azeotropic mixtures. Isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + potassium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.642 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-01-01

93

Isobaric vapor-liquid equilibrium for ethanol + water + strontium nitrate  

SciTech Connect

The effect of salts on the vapor-liquid equilibrium of solvent mixtures is of considerable interest in the separation of close boiling and azeotropic mixtures. The salt effect has been studied by many researchers. Most investigations have been limited to measurements on the saturated salt solutions. Isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + strontium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.672, has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain)] [Univ. de Valencia (Spain)

1996-07-01

94

Liquid Water Dynamics in a Model Polymer Electrolyte Fuel Cell Flow Channel  

E-print Network

Liquid Water Dynamics in a Model Polymer Electrolyte Fuel Cell Flow Channel by Chris Miller means, without the permission of the author. #12;ii Supervisory Committee Liquid Water Dynamics Dr. Sadik Dost, Department of Mechanical Engineering Departmental Member Water management

Victoria, University of

95

Entropy of Liquid Water from Ab Initio Molecular Dynamics  

NASA Astrophysics Data System (ADS)

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)

Spanu, Leonardo; Zhang, Cui; Galli, Giulia

2012-02-01

96

On the Stability of Liquid Water on Present Day Mars  

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

97

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

NASA Astrophysics Data System (ADS)

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.

Harris, P.; Presles, H. N.

1982-11-01

98

Nature of proton transport in a water-filled carbon nanotube and in liquid water  

E-print Network

Proton transport (PT) in bulk liquid water and within a thin water-filled carbon nanotube has been examined with ab initio pathintegral molecular dynamics (PIMD). Barrierless proton transfer is observed in each case when quantum nuclear effects (QNEs) are accounted for. The key difference between the two systems is that in the nanotube facile PT is facilitated by a favorable prealignment of water molecules, whereas in bulk liquid water solvent reorganization is required prior to PT. Configurations where the quantum excess proton is delocalized over several adjacent water molecules along with continuous interconversion between different hydration states reveals that, as in liquid water, the hydrated proton under confinement is best described as a fluxional defect, rather than any individual idealized hydration state such as Zundel, Eigen, or the so-called linear H7O3+ complex along the water chain. These findings highlight the importance of QNEs in intermediate strength hydrogen bonds (HBs) and explain why H+ ...

Chen, Ji; Zhang, Qianfan; Michaelides, Angelos; Wang, Enge

2014-01-01

99

Satellite Remote Sensing of the Liquid Water Sensitivity in Water Clouds  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

100

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

SciTech Connect

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 {pi}-{pi} 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.

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

2012-03-15

101

Isobaric vapor-liquid equilibrium for ethanol + water + sodium nitrate  

SciTech Connect

The salt effect on the vapor-liquid equilibrium of mixed solvents provides a potential technique of extractive distillation, in which a dissolved salt, rather than a liquid additive, is used as the separating agent. This salt distillation process has been used in the purification of close-boiling, azeotropic, and other systems which are difficult to separate. The isobaric vapor-liquid equilibrium for ethanol (1) + water (2) + sodium nitrate (3) at various concentrations of salt and with ethanol mole fractions from 0 to 0.774 has been measured at 100.0 kPa. The results were correlated by assuming that the salt was in ionic form and it was associated only with the water.

Pena, M.P.; Vercher, E.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica] [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1996-09-01

102

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

SciTech Connect

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.

Perahia, Dvora, Dr. (Clemson University, Clemson, SC); Pierce, Flint (Clemson University, Clemson, SC); Tsige, Mesfin (Southern Illinois University, Carbondale, IL); Grest, Gary Stephen, Dr.

2008-08-01

103

Release of liquid water from the space shuttle  

Microsoft Academic Search

Groundbased and onboard video images of a sunlit Shuttle Orbiter water dump are interpreted as showing that the continuous ~1 mm diameter liquid stream quickly breaks up in near-vacuum to form ice\\/snow particles of two characteristic sizes. Discrete large droplets (shown from laboratory measurements, to have diameters comparable with that of the initial coherent quasicylinder) are most evident in the

C. P. Pike; D. J. Knecht; R. A. Viereck; E. Murad; I. L. Kofsky; M. A. Maris; N. H. Tran; G. Ashley; L. Twist; M. E. Gersh; J. B. Elgin; A. Berk; A. T. Stair; J. P. Bagian; J. F. Buchli

1990-01-01

104

Boiling-up of liquid nitrogen jet in water  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

105

Glass transition in biomolecules and the liquid-liquid critical point of water  

E-print Network

Using molecular dynamics simulations, we investigate the relation between the dynamic transitions of biomolecules (lysozyme and DNA) and the dynamic and thermodynamic properties of hydration water. We find that the dynamic transition of the macromolecules, sometimes called a ``protein glass transition'', occurs at the temperature of dynamic crossover in the diffusivity of hydration water, and also coincides with the maxima of the isobaric specific heat $C_P$ and the temperature derivative of the orientational order parameter. We relate these findings to the hypothesis of a liquid-liquid critical point in water. Our simulations are consistent with the possibility that the protein glass transition results from crossing the Widom line, which is defined as the locus of correlation length maxima emanating from the hypothesized second critical point of water.

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

2006-03-21

106

Detection of Numerous Y Chromosome Biallelic Polymorphisms by Denaturing High-Performance Liquid Chromatography  

Microsoft Academic Search

Y chromosome haplotypes are particularly useful in deciphering human evolutionary history because they accentuate the effects of drift, migration, and range expansion. Significant acceleration of Y biallelic marker discovery and subsequent typing involving heteroduplex detection has been achieved by implementing an innovative and cost-efficient method called denaturing high-performance liquid chromatography (DHPLC). The power of the method resides in its sensitivity

Peter A. Underhill; Li Jin; Alice A. Lin; S. Qasim Mehdi; Trefor Jenkins; Douglas Vollrath; Ronald W. Davis; L. Luca Cavalli-Sforza; Peter J. Oefner

107

Interaction and permeability of water with liquid crystalline thermoset  

NASA Astrophysics Data System (ADS)

The complex transport behavior of water in both liquid crystalline thermoset and non-liquid crystalline thermoset systems were investigated. The liquid crystalline thermoset was 4,4'-diglycidyloxy-alpha-methylstilbene with sulfanilamine (SAA) as the crosslinking agent, the non-liquid crystalline thermoset the diglycidyl ether of bisphenol A. The liquid crystalline thermosets have higher barrier properties than isotropic non-LC epoxy resins. The efficient chain packing of the smectic mesophase of the liquid crystalline thermosets is attributed as the main factor for this difference. Permeation testing results show that the diffusion coefficient, permeability, and solubility coefficient depend on the amine/epoxide functional ratio. FTIR results confirmed that hydrophilic groups in the crosslinked network are one of the major factors that control the sorption and diffusion of water in epoxy resins. Two possible water-epoxy hydrogen bond configurations are identified, namely hydrogen bond formation of water to amine groups and hydrogen bond formation of water molecules to hydroxyl groups. Thus, diffusion of water molecules into epoxy resins depends on two major factors, namely, the availability of appropriate microvoids in the cured network and the interaction between the water molecules and the epoxy resin matrix. Depression of glass transition temperature was revealed by dynamic mechanical thermal analysis. The intrinsic moisture sensitivity of the epoxy resins is traceable directly to the molecular structure of the network. The presence of polar groups provides the chemical basis for moisture sensitivity. The entropy model can satisfactorily describe the nature of the depression of glass transition temperature. The hypothesis of a heterogeneous network was confirmed by phase images of atomic force microscopy for all of the epoxy samples. High crosslinked domains are surrounded by low crosslinked regions. Quantitative analysis of phase images shows that the relative amount of hard-phase changes with amine/epoxide functional ratio. Based on the analysis of morphology and interaction of water-epoxy resin, a theoretical model for the diffusion coefficient was set up for the first time by considering two factors: morphology and hydrogen bonding. This model relates the fraction of the hard-phase and the hydrogen bonding capacity to the experimental diffusion coefficients.

Feng, Jianxun

108

Switchable water: microfluidic investigation of liquid-liquid phase separation mediated by carbon dioxide.  

PubMed

Increase in the ionic strength of water that is mediated by the reaction of carbon dioxide (CO2) with nitrogenous bases is a promising approach toward phase separation in mixtures of water with organic solvents and potentially water purification. Conventional macroscale studies of this complicated process are challenging, due to its occurrence via several consecutive and concurrent steps, mass transfer limitation, and lack of control over gas-liquid interfaces. We report a new microfluidic strategy for fundamental studies of liquid-liquid phase separation mediated by CO2 as well as screening of the efficiency of nitrogenous agents. A single set of microfluidic experiments provided qualitative and quantitative information on the kinetics and completeness of water-tetrahydrofuran phase separation, the minimum amount of CO2 required to complete phase separation, the total CO2 uptake, and the rate of CO2 consumption by the liquid mixture. The efficiency of tertiary diamines with different lengths of alkyl chain was examined in a time- and labor-efficient manner and characterized with the proposed efficiency parameter. A wealth of information obtained using the MF methodology can facilitate the development of new additives for switchable solvents in green chemistry applications. PMID:25079335

Lestari, Gabriella; Abolhasani, Milad; Bennett, Darla; Chase, Preston; Günther, Axel; Kumacheva, Eugenia

2014-08-27

109

Anisotropic behavior of water in ferroelectric liquid crystals.  

PubMed

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

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

2010-05-01

110

Stock Identification of Atlantic Cod in U.S. Waters Using Microsatellite and Single Nucleotide Polymorphism DNA Analyses  

Microsoft Academic Search

Management of Atlantic cod Gadus morhua in U.S. waters is based on a two-stock model composed of stocks from (1) the Gulf of Maine (GOM) and (2) Georges Bank (GB) and areas south; however, evidence suggests a more fine-scale structuring. We used microsatellite and single nucleotide polymorphism (SNP) analyses to investigate the stock structure of Atlantic cod in U.S. waters.

Isaac Wirgin; Adrienne I. Kovach; Lorraine Maceda; Nirmal K. Roy; John Waldman; David L. Berlinsky

2007-01-01

111

Probing Hydrophilic Interface of Solid/Liquid-Water by Nanoultrasonics  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

112

A continuous mixture of two different dimers in liquid water.  

PubMed

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

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

2014-10-21

113

Liquid-vapor oscillations of water in hydrophobic nanopores  

PubMed Central

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. PMID:12740433

Beckstein, Oliver; Sansom, Mark S. P.

2003-01-01

114

A quantitative account of quantum effects in liquid water  

SciTech Connect

We report quantum statistical mechanical simulations of liquid water with the TTM2.1-F flexible, polarizable interaction potential for water. The potential is the first representation of the molecular interaction that reproduces the converged Born-Oppenheimer potential energy surface obtained from systematically improvable electronic structure analysis of binding energies of water clusters. Proper quantum statistical simulation of properties allows for a quantitative account of the magnitude of quantum effects in liquid water. We report path integral quantum dynamical simulations of total length of 600 ps with a 0.05 fs time step for a periodic system of 256 molecules. The representation of the quantum effects was achieved using up to 32 replicas per atom. These allow for a quantitative description of the broadening of the radial distribution functions and the corresponding energy shifts in the heat of vaporization. Our best estimate for the enthalpy of the liquid from the results of the quantum simulations is in the range 10.4 ? 10.6 kcal/mol, in agreement with the experimental value of 10.51 kcal/mol. 1Battelle operates PNNL for the USDOE

Fanourgakis, Georgios S.; Schenter, Gregory K.; Xantheas, Sotiris S.

2006-10-14

115

Liquid Hot Water Pretreatment of Olive Tree Pruning Residues  

NASA Astrophysics Data System (ADS)

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.

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

116

John Arthur McLees, Jr. Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water at  

E-print Network

Copyright by John Arthur McLees, Jr. 2006 #12;Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water in Engineering The University of Texas at Austin May, 2006 #12;Vapor-Liquid Equilibrium of Monoethanolamine/Piperazine/Water

Rochelle, Gary T.

117

Local order of liquid water at the electrochemical interface  

E-print Network

We study the structure and dynamics of liquid water in contact with Pd and Au (111) surfaces using \\emph{ab initio} molecular dynamics simulations with and without van der Waals interactions. Our results show that the structure of water at the interface of these two metals is very different. For Pd, we observe the formation of two different domains of preferred orientations, with opposite net interfacial dipoles. One of these two domains has a large degree of in-plane hexagonal order. For Au a single domain exists with no in-plane order. For both metals, the structure of liquid water at the interface is strongly dependent on the use of dispersion forces. The origin of the structural domains observed in Pd is associated to the interplay between water/water and water/metal interactions. This effect is strongly dependent on the charge transfer that occurs at the interface, and which is not modeled by current state of the art semi-empirical force fields.

Pedroza, Luana S; Fernández-Serra, M -V

2014-01-01

118

Water: two liquids divided by a common hydrogen bond.  

PubMed

The structure of water is the subject of a long and ongoing controversy. Unlike simpler liquids, where atomic interactions are dominated by strong repulsive forces at short distances and weaker attractive (van der Waals) forces at longer distances, giving rise to local atomic coordination numbers of order 12, water has pronounced and directional hydrogen bonds which cause the dense liquid close-packed structure to open out into a disordered and dynamic network, with coordination number 4-5. Here I show that water structure can be accurately represented as a mixture of two identical, interpenetrating, molecular species separated by common hydrogen bonds. Molecules of one type can form hydrogen bonds with molecules of the other type but cannot form hydrogen bonds with molecules of the same type. These hydrogen bonds are strong along the bond but weak with respect to changes in the angle between neighboring bonds. The observed pressure and temperature dependence of water structure and thermodynamic properties follow naturally from this choice of water model, and it also gives a simple explanation of the enduring claims based on spectroscopic evidence that water is a mixture of two components. PMID:21612286

Soper, Alan K

2011-12-01

119

Polymorphism and polyamorphism in bilayer water confined to slit nanopore under high pressure  

PubMed Central

A distinctive physical property of bulk water is its rich solid-state phase behavior, which includes 15 crystalline (ice I–ice XIV) and at least 3 glassy forms of water, namely, low-density amorphous, high-density amorphous, and very-high-density amorphous (VHDA). Nanoscale confinement adds a new physical variable that can result in a wealth of new quasi-2D phases of ice and amorphous ice. Previous computer simulations have revealed that when water is confined between two flat hydrophobic plates about 7–9 Å apart, numerous bilayer (BL) ices (or polymorphs) can arise [e.g., BL-hexagonal ice (BL-ice I)]. Indeed, growth of the BL-ice I through vapor deposition on graphene/Pt(111) substrate has been achieved experimentally. Herein, we report computer simulation evidence of pressure-induced amorphization from BL-ice I to BL-amorphous and then to BL-VHDA2 at 250 K and 3 GPa. In particular, BL-VHDA2 can transform into BL-VHDA1 via decompression from 3 to 1.5 GPa at 250 K. This phenomenon of 2D polyamorphic transition is akin to the pressure-induced amorphization in 3D ice (e.g., from hexagonal ice to HDA and then to VHDA via isobaric annealing). Moreover, when the BL-ice I is compressed instantly to 6 GPa, a new very-high-density BL ice is formed. This new phase of BL ice can be viewed as an array of square ice nanotubes. Insights obtained from pressure-induced amorphization and crystallization of confined water offer a guide with which to seek a thermodynamic path to grow a new form of methane clathrate whose BL ice framework exhibits the Archimedean 4?82 (square-octagon) pattern. PMID:23236178

Bai, Jaeil; Zeng, Xiao Cheng

2012-01-01

120

Reaction of catalytic oxidation by liquid water and its application to waste water purification  

SciTech Connect

In this paper the results of experiments and some considerations of theoretical and practical problems devoted to a new type of chemical reaction--oxidation of organic substances by liquid water with the aid of noble metal catalyst--are given. Some problems of application such as reaction to self-purification of industrial waste waters are also considered.

Ioffe, I.I. [All-Union Inst. of Pulp and Paper Industry, Leningrad (Russian Federation)] [All-Union Inst. of Pulp and Paper Industry, Leningrad (Russian Federation); Rubinskaya, E.V. [All-Union Inst. of Petrochemical Processes, Leningrad (Russian Federation)] [All-Union Inst. of Petrochemical Processes, Leningrad (Russian Federation)

1997-06-01

121

Stable and water-tolerant ionic liquid ferrofluids.  

PubMed

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

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

2011-03-01

122

Nucleationand surface induced crystallization in supercooled liquid water  

NASA Astrophysics Data System (ADS)

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)

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

2010-03-01

123

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

Code of Federal Regulations, 2013 CFR

...What solid and liquid wastes and discharges information and cooling water intake information...solid and liquid wastes and discharges information and cooling water intake information...solid and liquid wastes and discharges information and cooling water intake...

2013-07-01

124

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

Code of Federal Regulations, 2012 CFR

...What solid and liquid wastes and discharges information and cooling water intake information...solid and liquid wastes and discharges information and cooling water intake information...solid and liquid wastes and discharges information and cooling water intake...

2012-07-01

125

A Bayesian algorithm for the retrieval of liquid water cloud properties from microwave radiometer  

E-print Network

A Bayesian algorithm for the retrieval of liquid water cloud properties from microwave radiometer content and effective radius profiles of nonprecipitating liquid water clouds using millimeter wavelength liquid water content of 0.112 g/m3 , and mean effective radius of 7.8 mm. The Bayesian method

126

Evaluating specific error characteristics of microwave-derived cloud liquid water products  

E-print Network

Evaluating specific error characteristics of microwave-derived cloud liquid water products Thomas J errors and cloud inhomogeneity effects in cloud liquid water path (LWP) products derived from passive error characteristics of microwave-derived cloud liquid water products, Geophys. Res. Lett., 34, L22807

Christopher, Sundar A.

127

Using the phase diagram of liquid water to search for life  

Microsoft Academic Search

The correlation between liquid water and life may be our most reliable tool in the search for extraterrestrial life. To help develop this tool, we explore the complex relationship between liquid water, partial pressure, and solute freezing point depression on Earth and Mars and discuss the conditions under which liquid water is metastable on Mars. We establish the physical conditions

E. G. Jones; C. H. Lineweaver

2012-01-01

128

Microwave radiometer measurements at Liquid water path algorithm development and accuracy  

E-print Network

1 Microwave radiometer measurements at Chilbolton Liquid water path algorithm development Project Report #12;2 CONTENTS 1. INTRODUCTION. 1.1Liquid water clouds 1.2Microwave emission from the atmosphere 1.3Liquid water path retrieval 2. MICROWAVE RADIOMETERS. 2.1Radiometer description. 2.2 Radiometer

Reading, University of

129

Evaluation of ground-based remotely sensed liquid water cloud properties using shortwave radiation measurements  

E-print Network

Evaluation of ground-based remotely sensed liquid water cloud properties using shortwave radiation 1. Introduction The microphysical and optical properties of liquid water clouds are important parameters for studying cloud­radiation interactions. The amount of liquid water droplets, their particle

Haak, Hein

130

Liquid water transport in fuel cell gas diffusion layers Aimy Ming Jii Bazylak  

E-print Network

Liquid water transport in fuel cell gas diffusion layers by Aimy Ming Jii Bazylak Bachelor means, without the permission of the author. #12;ii Liquid water transport in fuel cell gas diffusion State University) Abstract Liquid water management has a major impact on the performance and durability

Victoria, University of

131

26Al and liquid water environments in comets.  

NASA Astrophysics Data System (ADS)

The authors review the different computations performed in the past, and discuss the effects of heating by radioactives in general, 26Al in particular, and the phase transition from amorphous to crystalline ice. Cooling mechanisms include heat conduction through the ice, and heat carried by the flow of gas through the porous nucleus. The most recent models show that conditions for producing liquid water can be achieved only under rather contrived circumstances.

Podolak, M.; Prialnik, D.

132

Energy loss measurement of protons in liquid water  

Microsoft Academic Search

The proton stopping power of liquid water was, for the first time, measured in the energy range 4.7-15.2 MeV. The proton energies were determined by the time-of-flight transmission technique with the microchannel plate detectors, which were especially developed for timing applications. The results are compared to the literature values (from ICRU Report 49 (1993) and Janni's tabulation (1982 At. Data

T. Siiskonen; H. Kettunen; K. Peräjärvi; A. Javanainen; M. Rossi; W. H. Trzaska; J. Turunen; A. Virtanen

2011-01-01

133

Measuring Low Concentrations of Liquid Water in Soil  

NASA Technical Reports Server (NTRS)

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.

Buehler, Martin

2009-01-01

134

Optically Thin Liquid Water Clouds: Their Importance and Our Challenge  

NASA Technical Reports Server (NTRS)

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.

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

135

Hydrogen bonds in liquid water are broken only fleetingly.  

PubMed

Although it is widely accepted that the local structure of liquid water has tetrahedral arrangements of molecules ordered by hydrogen bonds, the mechanism by which water molecules switch hydrogen-bonded partners remains unclear. In this mechanism, the role of nonhydrogen-bonded configurations (NHBs) between adjacent molecules is of particular importance. A molecule may switch hydrogen-bonding partners either (i) through thermally activated breaking of a hydrogen bond that creates a dangling hydrogen bond before finding a new partner or (ii) by infrequent but rapid switching events in which the NHB is a transition state. Here, we report a combination of femtosecond 2D IR spectroscopy and molecular dynamics simulations to investigate the stability of NHB species in an isotopically dilute mixture of HOD in D2O. Measured 2D IR spectra reveal that hydrogen-bonded configurations and NHBs undergo qualitatively different relaxation dynamics, with NHBs returning to hydrogen-bonded frequencies on the time scale of water's fastest intermolecular motions. Simulations of an atomistic model for the OH vibrational spectroscopy of water yield qualitatively similar 2D IR spectra to those measured experimentally. Analysis of NHBs in simulations by quenching demonstrates that the vast majority of NHBs are in fact part of a hydrogen-bonded well of attraction and that virtually all molecules return to a hydrogen-bonding partner within 200 fs. The results from experiment and simulation demonstrate that NHBs are intrinsically unstable and that dangling hydrogen bonds are an insignificant species in liquid water. PMID:16135564

Eaves, J D; Loparo, J J; Fecko, C J; Roberts, S T; Tokmakoff, A; Geissler, P L

2005-09-13

136

Liquid water can slip on a hydrophilic surface  

PubMed Central

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

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

2011-01-01

137

Looking for the rainbow on exoplanets covered by liquid and icy water clouds  

E-print Network

Looking for the primary rainbow in starlight that is reflected by exoplanets appears to be a promising method to search for liquid water clouds in exoplanetary atmospheres. Ice water clouds, that consist of water crystals instead of water droplets, could potentially mask the rainbow feature in the planetary signal by covering liquid water clouds. Here, we investigate the strength of the rainbow feature for exoplanets that have liquid and icy water clouds in their atmosphere, and calculate the rainbow feature for a realistic cloud coverage of Earth. We calculate flux and polarization signals of starlight that is reflected by horizontally and vertically inhomogeneous Earth--like exoplanets, covered by patchy clouds consisting of liquid water droplets or water ice crystals. The planetary surfaces are black. On a planet with a significant coverage of liquid water clouds only, the total flux signal shows a weak rainbow feature. Any coverage of the liquid water clouds by ice clouds, however, dampens the rainbow fea...

Karalidi, T; Hovenier, J W

2012-01-01

138

Liquid water simulations with the density fragment interaction approach.  

PubMed

We reformulate the density fragment interaction (DFI) approach [Fujimoto and Yang, J. Chem. Phys., 2008, 129, 054102.] to achieve linear-scaling quantum mechanical calculations for large molecular systems. Two key approximations are developed to improve the efficiency of the DFI approach and thus enable the calculations for large molecules: the electrostatic interactions between fragments are computed efficiently by means of polarizable electrostatic-potential-fitted atomic charges; and frozen fragment pseudopotentials, similar to the effective fragment potentials that can be fitted from interactions between small molecules, are employed to take into account the Pauli repulsion effect among fragments. Our reformulated and parallelized DFI method demonstrates excellent parallel performance based on the benchmarks for the system of 256 water molecules. Molecular dynamics simulations for the structural properties of liquid water also show a qualitatively good agreement with experimental measurements including the heat capacity, binding energy per water molecule, and the radial distribution functions of atomic pairs of O-O, O-H, and H-H. With this approach, large-scale quantum mechanical simulations for water and other liquids become feasible. PMID:22466097

Hu, Xiangqian; Jin, Yingdi; Zeng, Xiancheng; Hu, Hao; Yang, Weitao

2012-06-01

139

Fractionation of sugar cane with hot, compressed, liquid water  

SciTech Connect

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.

Allen, S.G.; Kam, L.C.; Zemann, A.J.; Antal, M.J. Jr. [Univ. of Hawaii, Honolulu, HI (United States)] [Univ. of Hawaii, Honolulu, HI (United States)

1996-08-01

140

Selective extraction of emerging contaminants from water samples by dispersive liquid-liquid microextraction using functionalized ionic liquids.  

PubMed

Functionalized ionic liquids containing the tris(pentafluoroethyl)trifluorophosphate (FAP) anion were used as extraction solvents in dispersive liquid-liquid microextraction (DLLME) for the extraction of 14 emerging contaminants from water samples. The extraction efficiencies and selectivities were compared to those of an in situ IL DLLME method which uses an in situ metathesis reaction to exchange 1-butyl-3-methylimidazolium chloride (BMIM-Cl) to 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (BMIM-NTf(2)). Compounds containing tertiary amine functionality were extracted with high selectivity and sensitivity by the 1-(6-amino-hexyl)-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate (HNH(2)MPL-FAP) IL compared to other FAP-based ILs and the BMIM-NTf(2) IL. On the other hand, polar or acidic compounds without amine groups exhibited higher enrichment factors using the BMIM-NTf(2) IL. The detection limits for the studied analytes varied from 0.1 to 55.1 ?g/L using the traditional IL DLLME method with the HNH(2)MPL-FAP IL as extraction solvent, and from 0.1 to 55.8 ?g/L using in situ IL DLLME method with BMIM-Cl+LiNTf(2) as extraction solvent. A 93-fold decrease in the detection limit of caffeine was observed when using the HNH(2)MPL-FAP IL compared to that obtained using in situ IL DLLME method. Real water samples including tap water and creek water were analyzed with both IL DLLME methods and yielded recoveries ranging from 91% to 110%. PMID:21324466

Yao, Cong; Li, Tianhao; Twu, Pamela; Pitner, William R; Anderson, Jared L

2011-03-25

141

Shock wave initiated by an ion passing through liquid water  

SciTech Connect

We investigate the shock wave produced by an energetic ion in liquid water. This wave is initiated by a rapid energy loss when the ion moves through the Bragg peak. The energy is transferred from the ion to secondary electrons, which then transfer it to the water molecules. The pressure in the overheated water increases by several orders of magnitude and drives a cylindrical shock wave on a nanometer scale. This wave eventually weakens as the front expands further; but before that, it may contribute to DNA damage due to large pressure gradients developed within a few nanometers from the ion's trajectory. This mechanism of DNA damage may be a very important contribution to the direct chemical effects of low-energy electrons and holes.

Surdutovich, Eugene [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Department of Physics, Oakland University, Rochester, Michigan 48309 (United States); Solov'yov, Andrey V. [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany)

2010-11-15

142

Shock wave initiated by an ion passing through liquid water.  

PubMed

We investigate the shock wave produced by an energetic ion in liquid water. This wave is initiated by a rapid energy loss when the ion moves through the Bragg peak. The energy is transferred from the ion to secondary electrons, which then transfer it to the water molecules. The pressure in the overheated water increases by several orders of magnitude and drives a cylindrical shock wave on a nanometer scale. This wave eventually weakens as the front expands further; but before that, it may contribute to DNA damage due to large pressure gradients developed within a few nanometers from the ion's trajectory. This mechanism of DNA damage may be a very important contribution to the direct chemical effects of low-energy electrons and holes. PMID:21230508

Surdutovich, Eugene; Solov'yov, Andrey V

2010-11-01

143

Development of a liquid-fed water resistojet  

NASA Technical Reports Server (NTRS)

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 facilitatite 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.

Morren, W. Earl; Stone, James R.

1988-01-01

144

Nature of proton transport in a water-filled carbon nanotube and in liquid water.  

PubMed

Proton transport (PT) in bulk liquid water and within a thin water-filled carbon nanotube has been examined using ab initio path-integral molecular dynamics (PIMD). Barrierless proton transfer is observed in each case when quantum nuclear effects (QNEs) are accounted for. The key difference between the two systems is that in the nanotube facile PT is facilitated by a favorable pre-alignment of water molecules, whereas in bulk liquid water solvent reorganization is required prior to PT. Configurations where the quantum excess proton is delocalized over several adjacent water molecules along with continuous interconversion between different hydration states reveals that, as in liquid water, the hydrated proton under confinement is best described as a fluxional defect, rather than any individual idealized hydration state such as Zundel, Eigen, or the so-called linear H7O3(+) complex along the water chain. These findings highlight the importance of QNEs in intermediate strength hydrogen bonds (HBs) and explain why H(+) diffusion through nanochannels is impeded much less than other cations. PMID:23518762

Chen, Ji; Li, Xin-Zheng; Zhang, Qianfan; Michaelides, Angelos; Wang, Enge

2013-05-01

145

Gibbs free energy of liquid water derived from infrared measurements.  

PubMed

Infrared spectra of pure liquid water were recorded from 20 cm(-1) to 4000 cm(-1) at temperatures ranging from 263 K to 363 K. The evolution of connectivity, libration, bending and OH stretching bands as a function of temperature follows the evolution of the inter-molecular dynamics, and so gives insight into the internal energy averaged over the measurement time and space. A partition function, which takes into account the inter-molecular and intra-molecular modes of vibration of water, all variable with the molecular networking, was developed to convert this vibrational absorption behavior of water into its macroscopic Gibbs free energy, assuming the vibrational energy to feature most of the water energy. Calculated Gibbs free energies along the thermal range are in close agreement with the literature values up to 318 K. Above this temperature, contributions specific to the non H-bonded molecules must be involved to closely fit the thermodynamics of water. We discussed this temperature threshold in relation to the well-known isosbestic point. Generally speaking, our approach is valuable to convert the IR molecular data into mean field properties, a quantitative basis to predict how water behaves in natural or industrial settings. PMID:25319142

Bergonzi, Isabelle; Mercury, Lionel; Brubach, Jean-Blaise; Roy, Pascale

2014-10-22

146

Surface relaxation in liquid water and methanol studied by x-ray absorption spectroscopy  

E-print Network

in surface tension of these liquids. This result is consistent with surface vibrational spectroscopy, which of surface tension, but quanti- tative experimental measurements of liquid surface structure have been not be readily obtained for the surfaces of these liquids. The surface tension of liquid water is large 75 erg

Cohen, Ronald C.

147

Learning science through guided discovery: liquid water and molecular networks  

NASA Astrophysics Data System (ADS)

In every drop of water, down at the scale of atoms and molecules, there is a world that can fascinate anyone. The objective of “Learning science through guided discovery: liquid water and molecular networks” is to use advanced technology to provide a window into the submicroscopic, and thereby allow students to discover by themselves an entire new world. We are developing a coordinated two-fold approach to high school science teaching in which a cycle of hands-on activities, games, and experimentation is followed by a cycle of computer simulations employing the full power of computer animation to “ZOOM” into the depths of this newly discovered world. Pairing of laboratory experiments with corresponding simulations challenges students to understand multiple representations of concepts. We thereby provide students with the opportunity to work in a fashion analogous to that in which practicing scientists work - e.g., by “building up” to general principles from specific experiences. Moreover, the ability to visualize “real-time” dynamic motions allows for student-controlled graphic simulations on the molecular scale, and interactive guided lessons superior to those afforded by even the most artful of texts. While our general approach could be applied to a variety of topics, we have chosen to focus first on the most familiar of molecular networks, that of liquid water. Later we will test the generality of the approach by exploring macromolecules such as proteins and DNA.

Ostrovsky, Boris; Poole, Peter H.; Sciortino, Francesco; Eugene Stanley, H.; Trunfio, Paul

1991-09-01

148

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

An ionic liquid foam floatation coupled with ionic liquid dispersive liquid-liquid microextraction method was proposed for the extraction and concentration of 17-?-estradiol, 17-?-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

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

2014-11-01

149

Coupled cluster benchmarks of water monomers and dimers extracted from density-functional theory liquid water: The importance of monomer  

E-print Network

the cell,7­9 c basis set,10,33 d fictitious electron mass in Car­Parrinello MD simulations,34 and so on liquid water: The importance of monomer deformations Biswajit Santra,1 Angelos Michaelides,1,2,a functionals in simulations of liquid water, water monomers and dimers were extracted from a PBE simulation

Alavi, Ali

150

Cloud and rain liquid water statistics in the CHUVA campaign  

NASA Astrophysics Data System (ADS)

The purpose of this study is to present statistics related to the integration of cloud and rain liquid water and the profiles for different cloud types and regimes. From 2010 to 2012, the CHUVA project collected information regarding cloud and rain characteristics in different precipitation regimes in Brazil. CHUVA had four field campaigns between 2010 and 2011, located in the North, Northeast and Southeast regions of Brazil, covering the semi-arid, Amazon, coastal and mountain regions. The synergy of several instruments allowed us to classify rain events and describe the cloud processes regionally. Microwave radiometers, LiDAR, radar, and disdrometers were employed in this study. The rain type classification was made using vertical profiles of reflectivity (VPR) and polarimetric variables from dual polarization radar (XPOL). The integrated liquid water (ILWC) for non-precipitating clouds was retrieved with a microwave ground-based radiometer using a neural network. For rainy conditions, the profiles from the rain liquid water content (LWCR) and their integrated (ILWR) properties were estimated by Micro Rain Radar (MRR) and XPOL VPRs. For non-precipitating clouds, the ILWC values were larger for the sites in tropical regions, in particular near the coast, than for Southeast Brazil. For rainy cases, distinct LWCR profiles were observed for different rain classifications and regions. The differences are small for low rain rates and a distinction between different rainfall regimes is more evident for high rain rates. Vale and Belém clouds present the deepest layers and largest convective rain rates. The clouds in the Southeast region of Brazil (Vale do Paraíba) and North region (Belém) showed the largest reflectivity in the mixed and glaciated layers, respectively. In contrast, the Northeast coastal site (e.g. Fortaleza) showed larger values in the warm part of the clouds. Several analyses are presented, describing the cloud processes and the differences among the cloud types, rain rates and regions.

Calheiros, Alan J. P.; Machado, Luiz A. T.

2014-07-01

151

Accepted Manuscript Liquid freshwater transport and Polar Surface Water characteristics in the East  

E-print Network

Accepted Manuscript Liquid freshwater transport and Polar Surface Water characteristics in the East this article as: Nilsson, J., Björk, G., Rudels, B., Winsor, P., Torres, D., Liquid freshwater transport to the journal pertain. #12;ACCEPTED MANUSCRIPT Liquid freshwater transport and Polar Surface Water

Nilsson, Johan

152

Optimized solar-powered liquid desiccant system to supply building fresh water and cooling needs  

Microsoft Academic Search

This paper studies the feasibility of using a solar-powered liquid desiccant system to meet both building cooling and fresh water needs in Beirut humid climate using parabolic solar concentrators as a heat source for regenerating the liquid desiccant. The water condensate is captured from the air leaving the regenerator. An integrated model of solar-powered calcium chloride liquid desiccant system for

N. Audah; N. Ghaddar; K. Ghali

2011-01-01

153

Elucidating the mechanism of selective ion adsorption to the liquid water surface  

E-print Network

of capillary waves and with a competition between ion hydration energy and the neat liquid's surface tensionElucidating the mechanism of selective ion adsorption to the liquid water surface Dale E. Ottena,1 of temperature-dependent adsorption free energy for a prototypical inorganic ion at the liquid water surface

Geissler, Phillip

154

Reaction of water vapor with a clean liquid uranium surface  

SciTech Connect

To study the reaction of water vapor with uranium, we have exposed clean liquid uranium surfaces to H/sub 2/O under UHV conditions. We have measured the surface concentration of oxygen as a function of exposure, and determined the maximum attainable surface oxygen concentration X/sub 0//sup s/ as a function of temperature. We have used these measurements to estimate, close to the melting point, the solubility of oxygen (X/sub 0//sup b/, < 10/sup -4/) and its surface segregation coefficient ..beta../sup s/(> 10/sup 3/). 8 refs., 5 figs., 1 tab.

Siekhaus, W.

1985-10-24

155

Spin states of para-water and ortho-water molecule in gas and liquid phases  

E-print Network

Spin degrees of freedom of water molecule in gas and liquid state were investigated in order to provide a reasonable answer about the unsolved problem of a long-term behavior of water spin isomers. The approach used involves an assumption that molecules change their spin state from a pure state to a mixed one when they interact with some sorts of adsorbent surface. Some models and conceptions of the quantum information processing were used.

V. K. Konyukhov

2009-09-23

156

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

PubMed Central

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

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

2012-01-01

157

The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover  

NASA Astrophysics Data System (ADS)

The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover.

Cupane, Antonio; Fomina, Margarita; Schirò, Giorgio

2014-11-01

158

The boson peak of deeply cooled confined water reveals the existence of a low-temperature liquid-liquid crossover.  

PubMed

The Boson peak of deeply cooled water confined in the pores of a silica xerogel is studied by inelastic neutron scattering at different hydration levels to separate the contributions from matrix, water on the pore surfaces and "internal" water. Our results reveal that at high hydration level, where the contribution from internal water is dominant, the temperature dependence of the Boson peak intensity shows an inflection point at about 225 K. The complementary use of differential scanning calorimetry to describe the thermodynamics of the system allows identifying the inflection point as the signature of a water liquid-liquid crossover. PMID:25399175

Cupane, Antonio; Fomina, Margarita; Schirò, Giorgio

2014-11-14

159

Hot electron dominated rapid transverse ionization growth in liquid water.  

PubMed

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-?m-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

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

2011-06-20

160

Forecast model applications of retrieved three dimensional liquid water fields  

NASA Technical Reports Server (NTRS)

Forecasts are made for tropical storm Emily using heating rates derived from the SSM/I physical retrievals described in chapters 2 and 3. Average values of the latent heating rates from the convective and stratiform cloud simulations, used in the physical retrieval, are obtained for individual 1.1 km thick vertical layers. Then, the layer-mean latent heating rates are regressed against the slant path-integrated liquid and ice precipitation water contents to determine the best fit two parameter regression coefficients for each layer. The regression formulae and retrieved precipitation water contents are utilized to infer the vertical distribution of heating rates for forecast model applications. In the forecast model, diabatic temperature contributions are calculated and used in a diabatic initialization, or in a diabatic initialization combined with a diabatic forcing procedure. Our forecasts show that the time needed to spin-up precipitation processes in tropical storm Emily is greatly accelerated through the application of the data.

Raymond, William H.; Olson, William S.

1990-01-01

161

X-ray study of the structure of liquid water  

NASA Astrophysics Data System (ADS)

The radial distribution function (RDF) of liquid water has been determined by x-ray scattering. Using a free-standing water jet and a diffracted beam analyzer to separate the Compton from the elastic scattering experimentally, several significant sources of error have been eliminated in the experiment. These have enabled the collection of quality data out to 19.7 A?-1. Data were collected both at 278 K and at 296 K. Our RDF presents fine structure, particularly, a distinct peak at 3.4 A? and a peak split at 4.5 A?. These features cannot be interpreted by a simple tetrahedral configuration suggested by continuum models. The uncertainties due to the truncation effects and the choice of scattering factors are found to have little influence on the RDF at intermolecular distances.

Fu, Ling; Bienenstock, Arthur; Brennan, Sean

2009-12-01

162

Rapid determination of octanol-water partition coefficient using vortex-assisted liquid-liquid microextraction.  

PubMed

Vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography (HPLC) is proposed here for the rapid determination of octanol-water partitioning coefficients (Kow). VALLME uses vortex agitation, a mild emulsification procedure, to disperse microvolumes of octanol in the aqueous phase thus increasing the interfacial contact area and ensuring faster partitioning rates. With VALLME, 2min were enough to achieve equilibrium conditions between the octanolic and aqueous phases. Upon equilibration, separation was achieved using centrifugation and the octanolic microdrop was collected and analyzed in a HPLC system. Six model compounds with logKow values ranging between ?0.5 and 3.5 were used during the present investigations. The proposed method produced logKow values that were consistent with previously published values and the recorded uncertainty was well within the acceptable log unit range. Overall, the key features of the proposed Kow determination procedure comprised speed, reliability, simplicity, low cost and minimal solvent consumption. PMID:24468238

Román, Iván P; Mastromichali, Anna; Tyrovola, Konstantina; Canals, Antonio; Psillakis, Elefteria

2014-02-21

163

Novel multifunctional acceptor phase additive of water-miscible ionic liquid in hollow-fiber protected liquid phase microextraction  

Microsoft Academic Search

In this paper, water-miscible ionic liquid (IL) such as 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) is introduced for the first time as a novel multifunctional acceptor phase additive in hollow-fiber protected liquid phase microextraction (HF-LPME). For investigating the performances of [BMIM]Cl, it was respectively mixed with NaOH, HCl and deionized water. And their extraction performance was preliminary evaluated with alkaline compounds (clenbuterol, metoprolol,

Wei Liu; Zhenyi Wei; Qing Zhang; Fang Wu; Zian Lin; Qiaomei Lu; Fen Lin; Guonan Chen; Lan Zhang

164

Combustion of Nano-Aluminum and Liquid Water G.A. Risha, S.F. Son  

E-print Network

to underwater propulsion, since the reaction is extremely exothermic and the water (oxidizer) need of nano-aluminum (nAl) and liquid water has been conducted. In particular, linear and mass-burning rates-deflagration on nAl and liquid water without the use of any additional gelling agent. Steady-state burning rates

Yang, Vigor

165

Journal of Power Sources 170 (2007) 334344 Experimental investigation of liquid water formation and transport  

E-print Network

Journal of Power Sources 170 (2007) 334­344 Experimental investigation of liquid water formation 3 April 2007 Available online 18 April 2007 Abstract Liquid water formation and transport were. We examined the effectiveness of various gas diffusion layer (GDL) materials in removing water away

Prasad, Ajay K.

166

Determination of the Liquid Water Diffusivity from Transient Moisture Transfer Experiments  

Microsoft Academic Search

The Boltzmann transformation method is used to determine the liquid water diffusivity from moisture content profiles as measured in a capillary water absorption experiment. An inter-laboratory comparison for analyzing the reliability of the determination method showed that the inaccuracy in the liquid water diffusivity is caused by scatter in the transformed data and by uncertainty in the boundary conditions at

J. Carmeliet; H. Hens; S. Roels; OCG Adan; HJP Brocken; R. Cerny; Z. Pavlik; C. Hall; K. Kumaran; L. Pel

2004-01-01

167

Liquid Water Storage, Distribution, and Removal from Diffusion Media in PEFCS  

E-print Network

. Available electronically August 28, 2006. The management of water within a polymer electrolyte fuel cell channels to the elec- trodes, ii removal of vapor- and liquid-phase water produced in the cell, iiiLiquid Water Storage, Distribution, and Removal from Diffusion Media in PEFCS J. J. Kowal, A

Mench, Matthew M.

168

Liquid-metal/water interactions in a shock tube  

SciTech Connect

To investigate liquid-metal (fuel)/water (coolant) interactions, a vertical shock tube has been designed and constructed. A series of tests was conducted with gallium, indium, lead, and tin as the fuel materials at either low (T{sub f} {approximately} 300 C) or high fuel temperature (T{sub f} {approximately} 600 C), with water at room temperature (low {Tc}) and in the range of T{sub c} = 56 to 67 C (high {Tc}), and with driving pressures from 0.25 to 1.22 MPa. These materials were tested to determine their compatibility for potential use in liquid-metal divertor systems for fusion power plants. The increase in fuel and water temperature, as well as the increase of driving pressure, caused more energetic interactions to occur. High T{sub f} tin and lead interactions, and high T{sub f} and {Tc} gallium and indium interactions were the most energetic. Stronger interactions produced finer debris fragments. In high T{sub f} gallium and indium interactions, small superficial oxidation was observed. For the first two pulses, larger ratios of compression-(compression of expansion vessel gas)to-expansion work correspond to the experiments with higher fuel and coolant temperatures. For the first pulse, only work ratio values of the most energetic experiments are larger than those of isothermal experiments. Consequently, for such experiments, the impulse values of second pulses are the largest. Higher values of the conversion ratio for the first pulse correspond to more energetic interactions. Even for the most energetic experiments, the conversion ratio is no higher than 1.2%, and no more than 15% (or a few millimeters-thick surface layer) of the initially loaded fuel participated in the interaction, assuming equal initial volumes of fuel and coolant.

Vukovic, G.; Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States). Nuclear Engineering and Engineering Physics Dept.

1996-07-01

169

Liquid water content variation with altitude in clouds over Europe  

NASA Astrophysics Data System (ADS)

Cloud water content is one of the most fundamental measurements in cloud physics. Knowledge of the vertical variability of cloud microphysical characteristics is important for a variety of reasons. The profile of liquid water content (LWC) partially governs the radiative transfer for cloudy atmospheres, LWC profiles improves our understanding of processes acting to form and maintain cloud systems and may lead to improvements in the representation of clouds in numerical models. Presently, in situ airborne measurements provide the most accurate information about cloud microphysical characteristics. This information can be used for verification of both numerical models and cloud remote sensing techniques. The aim of this paper was to analyze the liquid water content (LWC) measurements in clouds, in time of the aircraft flights. The aircraft and its platform ATMOSLAB - Airborne Laboratory for Environmental Atmospheric Research is property of the National Institute for Aerospace Research "Elie Carafoli" (INCAS), Bucharest, Romania. The airborne laboratory equipped for special research missions is based on a Hawker Beechcraft - King Air C90 GTx aircraft and is equipped with a sensors system CAPS - Cloud, Aerosol and Precipitation Spectrometer (30 bins, 0.51-50 m). The processed and analyzed measurements are acquired during 4 flights from Romania (Bucharest, 44°25'57?N 26°06'14?E) to Germany (Berlin 52°30'2?N 13°23'56?E) above the same region of Europe. The flight path was starting from Bucharest to the western part of Romania above Hungary, Austria at a cruse altitude between 6000-8500 m, and after 5 hours reaching Berlin. In total we acquired data during approximately 20 flight hours and we presented the vertical and horizontal LWC variations for different cloud types. The LWC values are similar for each type of cloud to values from literature. The vertical LWC profiles in the atmosphere measured during takeoff and landing of the aircraft have shown their dependence of the meteorological parameters.

Andreea, Boscornea; Sabina, Stefan

2013-04-01

170

Relationship between optical extinction and liquid water content in fogs  

NASA Astrophysics Data System (ADS)

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 ?m) 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.

Klein, C.; Dabas, A.

2014-05-01

171

Determination of phenolic compounds in water samples by HPLC following ionic liquid dispersive liquid-liquid microextraction and cold-induced aggregation  

Microsoft Academic Search

We report on the determination of bisphenol A and 2-naphthol in water samples using ionic liquid cold-induced aggregation\\u000a dispersive liquid-liquid microextraction combined with HPLC. Parameters governing the extraction efficiency (disperser solvent,\\u000a volume of extraction and disperser solvent, pH, temperature, extraction time) were optimized and resulted in enrichment factors\\u000a of 112 for bisphenol A and of 186 for 2-naphthol. The calibration

Xinyu Jiang; Hui Zhang; Xiaoqing Chen

172

Crystallization of the polymorphs of succinic acid via sublimation at different temperatures in the presence or absence of water and isopropanol vapor  

NASA Astrophysics Data System (ADS)

? Succinic acid was prepared from the gas phase via the sublimation of the ? form. Two sublimation methods including sublimation with carrier gas and sublimation in the presence of foreign molecules were employed. The influence of the sublimation temperature and the crystallization temperature on the polymorph and morphology are presented and discussed. At high supersaturation, the ? polymorph predominated, and at low supersaturation the ? polymorph was obtained. The influences of water and isopropanol in the gas phase on the morphology of ? succinic acid grown via the sublimation are presented and compared with morphologies of crystals grown from solution.

Yu, Qiushuo; Dang, Leping; Black, Simon; Wei, Hongyuan

2012-02-01

173

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

SciTech Connect

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.

Tjernstroem, M. (Uppsala Univ. (Sweden))

1993-04-01

174

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

175

Liquid-like water in the upper surface of Mars - presence and properties  

NASA Astrophysics Data System (ADS)

Liquid layers of water can via adsorption develop on grain and mineral surfaces at and in the surface of Mars. The upper parts of these layers will freeze at temperatures clearly below the freezing point of bulk water (freezing point depression). This will be modeled in terms of a sandwich structure with layers of ice (top), liquid water (in between) and mineral surface (bottom) can evolve. Thickness (or number of mono-layers) of the liquid water layer and the related content of liquid-like water in dependence on the diurnal temperature variations, the freezing point depression temperatures of the unfrozen water, and the related equilibrium content of liquid water in surface soil are derived on the basis of this "sandwich model" with van der Waals interactions between the mineral-substrate and the ice layer. These results are discussed with respect to the mid- and low-latitudinal surface and shallow subsurface of Mars.

Möhlmann, D.

2007-08-01

176

Detachment of Liquid-Water Droplets from Gas-Diffusion Layers  

SciTech Connect

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.

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

2011-07-01

177

Conversion of lignocellulosics pretreated with liquid hot water to ethanol  

SciTech Connect

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.

Walsum, G.P. van; Laser, M.S.; Lynd, L.R. [Dartmouth College, Hanover, NH (United States)] [and others

1996-12-31

178

Electrokinetic Hydrogen Generation from Liquid WaterMicrojets  

SciTech Connect

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.

Duffin, Andrew M.; Saykally, Richard J.

2007-05-31

179

Energy loss measurement of protons in liquid water  

NASA Astrophysics Data System (ADS)

The proton stopping power of liquid water was, for the first time, measured in the energy range 4.7-15.2 MeV. The proton energies were determined by the time-of-flight transmission technique with the microchannel plate detectors, which were especially developed for timing applications. The results are compared to the literature values (from ICRU Report 49 (1993) and Janni's tabulation (1982 At. Data Nucl. Data Tables 27 147-339)) which are based on Bethe's formula and an agreement is found within the experimental uncertainty of 4.6%. Thus, earlier reported discrepancy between the experimental and literature stopping power values at lower energies was not observed at the energies considered in this experiment.

Siiskonen, T.; Kettunen, H.; Peräjärvi, K.; Javanainen, A.; Rossi, M.; Trzaska, W. H.; Turunen, J.; Virtanen, A.

2011-04-01

180

Energy loss measurement of protons in liquid water.  

PubMed

The proton stopping power of liquid water was, for the first time, measured in the energy range 4.7-15.2 MeV. The proton energies were determined by the time-of-flight transmission technique with the microchannel plate detectors, which were especially developed for timing applications. The results are compared to the literature values (from ICRU Report 49 (1993) and Janni's tabulation (1982 At. Data Nucl. Data Tables 27 147-339)) which are based on Bethe's formula and an agreement is found within the experimental uncertainty of 4.6%. Thus, earlier reported discrepancy between the experimental and literature stopping power values at lower energies was not observed at the energies considered in this experiment. PMID:21427483

Siiskonen, T; Kettunen, H; Peräjärvi, K; Javanainen, A; Rossi, M; Trzaska, W H; Turunen, J; Virtanen, A

2011-04-21

181

Influence of gravity on the collective molecular dynamics of liquid water: the case of the floating water bridge  

E-print Network

Quantum electrodynamics (QED) produces a picture of liquid water as a mixture of a low density coherent phase and an high density non-coherent phase. Consequently, the Archimedes principle prescribes that, within a gravitational field, liquid water should be made up, at surface, mainly of the coherent fraction, which becomes a cage where the gas-like non-coherent fraction is trapped, acquiring a non-vanishing pressure (vapor tension). Therefore, it is possible to probe the QED picture by observing the behavior of liquid water under reduced gravity conditions. The floating water bridge could be a useful test model.

Emilio Del Giudice; Giuseppe Vitiello

2010-09-29

182

Relationship between optical extinction and liquid water content in fogs  

NASA Astrophysics Data System (ADS)

Studies carried out in the late 1970s suggest 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 the present article, the validity of the linear relationship is revisited at 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 ?m) are detected, which was not the case in the late 1970s. The results confirm 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 droplets are made of pure water. This assumption is probably valid for big droplets, it may be questioned for small ones since droplets are formed from condensation nuclei of highly variable chemical composition. The study suggests the relationship is mostly sensitive to the real part of the refractive index and the sensitivity grows with the size of fog droplets. However, large fog droplets are more likely to have an index close to that of water since they are mainly composed of water.

Klein, C.; Dabas, A.

2013-11-01

183

Analysis of precipitable water vapor and liquid water path by microwave radiometer during 2001 - 2002  

NASA Astrophysics Data System (ADS)

Based on the observation of the Microwave Radiometer (MWR, WVR-1100) at Cheongju and Hapcheon in South Korea, the precipitable water vapor (PWV) and liquid water path (LWP) have been analyzed. Comparison of the PWVs measured by MWR at Cheongju and Hapcheon gives good agreement above the 0.9 of correlation coefficient with that of radiosonde at the two nearest sites (Osan and Gwangju), respectively. The PWVs show the seasonality, but do not the regional characteristics evidently. The LWP shows not only the seasonality but also regional difference. These regional characteristics seem come from the regional different solar radiation.

Yang, H.; Chang, K.; Lee, S.; Jang, Y.; Choi, Y.

2007-12-01

184

Liquid-Liquid Interface Study of Hydrocarbons, Alcohols, and Cationic Surfactants with Water  

NASA Astrophysics Data System (ADS)

Molecular interaction dynamics at liquid-liquid interface (LLI), involved nondispersive solution as compared with the interaction in bulk phase. Thereby, interfacial tension (IFT, mN/m) of LLI for four saturated hydrocarbons, six alcohols, and three cationic surfactants are reported at 298.15 K. The pentane, hexane, heptane, octane hydrocarbons and pentanol, hexanol, heptanol, 1-octanol, 2-octanol, and 1-decanol alcohols were used and IFT data were compared with 4 mm kg-1 dodecyltrimethylammoniumbromide (DTAB), trimethylsulfoxoniumiodide (TMSOI), methyltrioctylammoniumchloride (MTOAC) surfactants studied in benzene-water LLI. The IFT data are noted as hydrocarbons > DTAB > TMSOI > alcohols > MTOAC. The hydrocarbons and alcohols decreased IFT within 16 to 49% and 87 to 92%, respectively, whereas the surfactants within 78.3 to 95.9%. The alcohols developed interaction similar to surfactants and are denoted as nonionic surfactants for making mixtures of low IFT with hydrophilic and hydrophobic interactions to the level of the surfactants. The pentanol and MTOAC caused similar decrease in IFT so the pentanol developed the hydrophilic and hydrophobic interactions of the strength of MTOAC. Comparatively, the hydrocarbons showed lower decrease but the octane showed 49% decrease in IFT. Thus, the hydrocarbon with longer alkyl chain and the alcohol with shorter behave as good surfactants. The hydrocarbons with inductive effect on sigma bond between carbon atoms in alkyl chain also weakened the IFT and influenced the hydrophobic interactions. The MTOAC with four octyl units reduced 96% IFT so inductive effects monitor LLI dynamics.

Singh, Man; Matsuoka, Hideki

185

Bonded stationary phases for reversed phase liquid chromatography with a water mobile phase: application to subcritical water extraction  

Microsoft Academic Search

Reversed phase high-performance liquid chromatography (RP-HPLC) is demonstrated for hydrophobic analytes such as aromatic hydrocarbons on a chemically bonded stationary phase and a mobile phase consisting of only water. Reversed phase liquid chromatography separations using a water-only mobile phase has been termed WRP-LC for water-only reversed phase LC. Reasonable capacity factors are achieved through the use of a non-porous silica

Toby E Young; Scott T Ecker; Robert E Synovec; Nathan T Hawley; Jonathan P Lomber; Chien M Wai

1998-01-01

186

Quench rates in air, water, and liquid nitrogen, and inference of temperature in volcanic eruption columns  

E-print Network

eruptions of the Mono Craters. Cooling rates of pyroclasts are inversely correlated with sample sizeQuench rates in air, water, and liquid nitrogen, and inference of temperature in volcanic eruption rate profiles of rhyolitic samples initially held at 720^750C and quenched in water, liquid nitrogen

Zhang, Youxue

187

Electrodeposition onto magnesium in air and water stable ionic liquids: From corrosion to successful plating  

Microsoft Academic Search

Magnesium is very reactive and therefore magnesium electroplating in aqueous solutions is hazardous. Mg is classified as a water sensitive substrate from the electrodeposition point of view. Therefore, it was suggested that ionic liquids be used as electrolytic solvents for electrodeposition onto Mg and its alloys. Five air and water stable ionic liquids based on choline chloride (ChCl) were investigated

A. Bakkar; V. Neubert

2007-01-01

188

In Situ Imaging of Liquid Water and Ice Formation in an Operating PEFC during Cold Start  

E-print Network

cell PEFC was developed to study liquid water and ice formation during startup from subzeroIn Situ Imaging of Liquid Water and Ice Formation in an Operating PEFC during Cold Start Shanhai Ge submitted May 25, 2006; revised manuscript received July 4, 2006. Available electronically August 29, 2006

189

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...

190

Near-Global Survey of Effective Droplet Radii in Liquid Water Clouds Using ISCCP Data  

Microsoft Academic Search

A global survey of cloud particle size variations can provide crucial constraints on how cloud processes determine cloud liquid water contents and their variation with temperature, and further, may indicate the magnitude of aerosol effects on clouds. A method, based on a complete radiative transfer model for AVHRR-measured radiances, is described for retrieving cloud particle radii in liquid water clouds

Qingyuan Han; William B. Rossow; Andrew A. Lacis

1994-01-01

191

Simulation of water mist suppression of small scale methanol liquid pool fires  

Microsoft Academic Search

The focus of this paper is on numerical modeling of methanol liquid pool fires and the suppression of these fires using water mist. A mathematical model is first developed to describe the evaporation and burning of liquid methanol. The complete set of unsteady, compressible Navier–Stokes equations are solved along with an Eulerian sectional water mist model. Heat transfer into the

Kuldeep Prasad; Chiping Li; K Kailasanath

1999-01-01

192

INFLUENCE OF WETTABILITY ON LIQUID WATER TRANSPORT IN GAS DIFFUSION LAYER OF PROTON EXCHANGE MEMBRANE FUEL  

E-print Network

INFLUENCE OF WETTABILITY ON LIQUID WATER TRANSPORT IN GAS DIFFUSION LAYER OF PROTON EXCHANGE to 3D systems, notably from binarised images of GDLs obtained by X ray microtomography. 1. INTRODUCTION that a detailed understanding of liquid water transport in the gas diffusion layer (GDL) is necessary

Paris-Sud XI, Université de

193

Stratocumulus Liquid Water Content from Dual-Wavelength Radar ROBIN J. HOGAN  

E-print Network

Stratocumulus Liquid Water Content from Dual-Wavelength Radar ROBIN J. HOGAN , NICOLAS GAUSSIAT ABSTRACT A technique is described to retrieve stratocumulus liquid water content (LWC) using the differential attenuation measured by vertically pointing radars at 35 GHz and 94 GHz. Millimeter-wave

Reading, University of

194

Living in a physical world IX. Making and maintaining liquid water  

Microsoft Academic Search

Metabolically active organisms contain water in its liquid phase – I believe no exceptions are known. Life’s domain consists of the intersection of the circumstances under which liquid water will persist and those at the earth’s surface – except as we artifi cially maintain some bit of that domain elsewhere. No single phase of a single compound so characterizes the

Steven Vogel

2006-01-01

195

Model for the structure of the liquid water network  

SciTech Connect

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.

Grunwald, E.

1986-09-17

196

Polymorphism of triphenyl phosphite  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

197

Polymorphism of triphenyl phosphite.  

PubMed

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. PMID:24628187

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

2014-03-14

198

Effects of water in film boiling over liquid metal melts  

SciTech Connect

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.

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

1986-01-01

199

Probing the interactions between ionic liquids and water: experimental and quantum chemical approach.  

PubMed

For an adequate choice or design of ionic liquids, the knowledge of their interaction with other solutes and solvents is an essential feature for predicting the reactivity and selectivity of systems involving these compounds. In this work, the activity coefficient of water in several imidazolium-based ionic liquids with the common cation 1-butyl-3-methylimidazolium was measured at 298.2 K. To contribute to a deeper insight into the interaction between ionic liquids and water, COSMO-RS was used to predict the activity coefficient of water in the studied ionic liquids along with the excess enthalpies. The results showed good agreement between experimental and predicted activity coefficient of water in ionic liquids and that the interaction of water and ionic liquids was strongly influenced by the hydrogen bonding of the anion with water. Accordingly, the intensity of interaction of the anions with water can be ranked as the following: [CF3SO3](-) < [SCN](-) < [TFA](-) < Br(-) < [TOS](-) < Cl(-) < [CH3SO3](-) [DMP](-) < [Ac](-). In addition, fluorination and aromatization of anions are shown to reduce their interaction with water. The effect of temperature on the activity coefficient of water at infinite dilution was measured by inverse gas chromatography and predicted by COSMO-RS. Further analysis based on COSMO-RS provided information on the nature of hydrogen bonding between water and anion as well as the possibility of anion-water complex formation. PMID:24467614

Khan, Imran; Kurnia, Kiki A; Mutelet, Fabrice; Pinho, Simão P; Coutinho, João A P

2014-02-20

200

Physica A 386 (2007) 729743 The puzzling unsolved mysteries of liquid water  

E-print Network

Physica A 386 (2007) 729­743 The puzzling unsolved mysteries of liquid water: Some recent progress Abstract Water is perhaps the most ubiquitous, and the most essential, of any molecule on earth. Indeed be like without water. Despite decades of research, however, water's puzzling properties

Stanley, H. Eugene

201

Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy  

E-print Network

bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water to produce quantitative structural models of liquid water.17,18 This approach has tried to link the pre- edge I , main-edge II , and postedge III regions indicated in Fig. 2 a to local water structures

202

Liquid-liquid phase transition model incorporating evidence for ferroelectric state near the lambda-point anomaly in supercooled water  

E-print Network

We propose a unified model combining the first-order liquid-liquid and the second-order ferroelectric phase transitions models and explaining various features of the $\\lambda$-point of liquid water within a single theoretical framework. It becomes clear within the proposed model that not only does the long-range dipole-dipole interaction of water molecules yield a large value of dielectric constant $\\epsilon$ at room temperatures, our analysis shows that the large dipole moment of the water molecules also leads to a ferroelectric phase transition at a temperature close to the lambda-point. Our more refined model suggests that the phase transition occurs only in the low density component of the liquid and is the origin of the singularity of the dielectric constant recently observed in experiments with supercooled liquid water at temperature T~233K. This combined model agrees well with nearly every available set of experiments and explains most of the well-known and even recently obtained results of MD simulations.

Peter O. Fedichev; Leonid I. Menshikov

2012-01-30

203

Development of an ionic liquid-based dispersive liquid-liquid micro-extraction method for the determination of phthalate esters in water samples.  

PubMed

Ionic liquid-based dispersive liquid-liquid micro-extraction (IL-DLLME) was coupled with high-performance liquid chromatography-ultraviolet (HPLC-UV) for the determination of four phthalate esters, including butyl benzyl phthalate, di-n-butyl phthalate, dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate in water samples. The mixture of ionic liquid (IL) and dispersive solvent was rapidly injected into 10 mL aqueous sample. Then, IL phase was separated by centrifugation and was determined by high-performance liquid chromatography-ultraviolet. The factors influencing the extraction efficiency, such as type and volume of IL, disperse solvent, extraction time, centrifuging time and ionic strength, were investigated and optimized. Under the optimized conditions, the extraction recoveries by the proposed ionic liquid-based dispersive liquid-liquid micro-extraction for the four phthalates ranged from 83.0 to 91.7%. The relative standard deviations were between 7.8 and 15%. The limits of quantification for four phthalates were between 10.6 and 28.5 ?g/L. The proposed method was successfully applied for the analysis of PAEs in tap, lake and treated wastewater samples. PMID:21604368

Sha, Chen; Yi-Sheng, Zhong; Shui-Yuan, Cheng; Tian, Qian; Hao, Sun

2011-07-01

204

Boson peak in deeply cooled confined water: a possible way to explore the existence of the liquid-to-liquid transition in water.  

PubMed

The boson peak in deeply cooled water confined in nanopores is studied with inelastic neutron scattering. We show that in the (P, T) plane, the locus of the emergence of the boson peak is nearly parallel to the Widom line below ? 1600 bar. Above 1600 bar, the situation is different and from this difference the end pressure of the Widom line is estimated. The frequency and width of the boson peak correlate with the density of water, which suggests a method to distinguish the hypothetical "low-density liquid" and "high-density liquid" phases in deeply cooled water. PMID:24972226

Wang, Zhe; Liu, Kao-Hsiang; Le, Peisi; Li, Mingda; Chiang, Wei-Shan; Leão, Juscelino B; Copley, John R D; Tyagi, Madhusudan; Podlesnyak, Andrey; Kolesnikov, Alexander I; Mou, Chung-Yuan; Chen, Sow-Hsin

2014-06-13

205

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

SciTech Connect

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.

Bo-Cai Gao; Goetz, A.F.H. (Univ. of Colorado, Boulder (United States))

1990-03-20

206

SOLIDPHASE EXTRACTION FOLLOWED BY DISPERXIVE LIQUID-LIQUID MICROEXTRACTION FOR THE SENSITIVE DETERMINATION OF CARBAMATES IN ENVIRONMENTAL WATER BY HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY  

Microsoft Academic Search

A new sample pretreatment method, solid-phase extraction combined with dispersive liquid–liquid microextraction (SPE-DLLME), was established for the sensitive determination of carbamates in environmental water samples. Three carbamates (carbofuran, carbaryl, pirimicarb) were extracted from watert samples by SPE. After the elution of the desired compounds from the sorbent using acetonitrile, DLLME technique was performed on the obtained solution. The analytes were

Shu Zhou; Bo Wu; Chao Ma; Yong Ye; Huaixia Chen

2012-01-01

207

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

NASA Technical Reports Server (NTRS)

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.

Yamauchi, S. T. (inventor)

1983-01-01

208

Retrieval of effective radius and liquid water path from ground-based instruments: A case study at Barrow, Alaska  

E-print Network

Retrieval of effective radius and liquid water path from ground- based instruments: A case study spectral measurements of path-integrated liquid water paths (PLWPs) are described. In one method the PLWP is compared with column measurements of liquid water path (LWP) from a dual channel microwave radiometer (MWR

Shupe, Matthew

209

Active and stable liquid water innovatively prepared using resonantly illuminated gold nanoparticles.  

PubMed

The properties of confined liquid water, or liquid water in contact with hydrophobic surfaces, are significantly different from those of bulk liquid water. However, all of water's commonly described properties are related to inert "bulk liquid water" which comprises a tetrahedral hydrogen-bonded network. In this work, we report an innovative and facile method for preparing small water clusters (SWCs) with reduced affinity hydrogen bonds by letting bulk water flow through supported Au nanoparticles (NPs) under resonant illumination to give NP-treated (AuNT) water at constant temperature. Utilizing localized surface plasmon resonance on illuminated Au NPs, the strong hydrogen bonds of bulk water can be disordered when water is located at the illuminated Au/water interface. The prepared SWCs are free of Au NPs. The energy efficiency for creating SWCs is ?17%. The resulting stable AuNT water exhibits distinct properties at room temperature, which are significantly different from the properties of untreated bulk water, examples being their ability to scavenge free hydroxyl and 2,2-diphenyl-1-picrylhydrazyl radicals and to effectively reduce NO release from lipopolysaccharide-induced inflammatory cells. PMID:24533852

Chen, Hsiao-Chien; Hwang, Bing-Joe; Mai, Fu-Der; Liu, Yu-Chuan; Lin, Chun-Mao; Kuo, Hsien-Shou; Chou, Duen-Suey; Lee, Ming-Jer; Yang, Kuang-Hsuan; Yu, Chung-Chin; Chen, Jiun-Rong; Lo, Tsui-Yun; Tsai, Hui-Yen; Yang, Chih-Ping; Wang, Chi; Hsieh, Hsiao-Ting; Rick, John

2014-03-25

210

X-Ray Spectroscopy of the Liquid Water Surface  

Microsoft Academic Search

We have developed a new experiment for probing molecular details of liquid-vapor interfaces of volatile substances and their solutions under equilibrium conditions. Electronic and geometric structures of interfacial molecules are probed by EXAFS and NEXAFS methods in the soft X-ray region, using the Advanced Light Source, Berkeley, CA. Liquids are introduced into a high vacuum environment through the use of

Richard Saykally

2004-01-01

211

Experimental evidence of the ferroelectric phase transition near the $\\lambda-$point in liquid water  

E-print Network

We studied dielectric properties of nano-sized liquid water samples confined in polymerized silicates MCM-41 characterized by the porous sizes \\sim 3-10nm. We report the direct measurements of the dielectric constant by the dielectric spectroscopy method at frequencies 25Hz-1MHz and demonstrate clear signatures of the second-order phase transition of ferroelectric nature at temperatures next to the \\lambda- point in the bulk supercooled water. The presented results support the previously developed polar liquid phenomenology and hence establish its applicability to model actual phenomena in liquid water.

Fedichev, P O; Bordonskiy, G S; Orlov, A O

2011-01-01

212

Temperature dependence of local solubility of hydrophobic molecules in the liquid-vapor interface of water.  

PubMed

One important aspect of the hydrophobic effect is that solubility of small, nonpolar molecules in liquid water decreases with increasing temperature. We investigate here how the characteristic temperature dependence in liquid water persists or changes in the vicinity of the liquid-vapor interface. From the molecular dynamics simulation and the test-particle insertion method, the local solubility ? of methane in the liquid-vapor interface of water as well as ? of nonpolar solutes in the interface of simple liquids are calculated as a function of the distance z from the interface. We then examine the temperature dependence of ? under two conditions: variation of ? at fixed position z and that at fixed local solvent density around the solute molecule. It is found that the temperature dependence of ? at fixed z depends on the position z and the system, whereas ? at fixed local density decreases with increasing temperature for all the model solutions at any fixed density between vapor and liquid phases. The monotonic decrease of ? under the fixed-density condition in the liquid-vapor interface is in accord with what we know for the solubility of nonpolar molecules in bulk liquid water under the fixed-volume condition but it is much robust since the solvent density to be fixed can be anything between the coexisting vapor and liquid phases. A unique feature found in the water interface is that there is a minimum in the local solubility profile ?(z) on the liquid side of the interface. We find that with decreasing temperature the minimum of ? grows and at the same time the first peak in the oscillatory density profile of water develops. It is likely that the minimum of ? is due to the layering structure of the free interface of water. PMID:25399181

Abe, Kiharu; Sumi, Tomonari; Koga, Kenichiro

2014-11-14

213

Temperature dependence of local solubility of hydrophobic molecules in the liquid-vapor interface of water  

NASA Astrophysics Data System (ADS)

One important aspect of the hydrophobic effect is that solubility of small, nonpolar molecules in liquid water decreases with increasing temperature. We investigate here how the characteristic temperature dependence in liquid water persists or changes in the vicinity of the liquid-vapor interface. From the molecular dynamics simulation and the test-particle insertion method, the local solubility ? of methane in the liquid-vapor interface of water as well as ? of nonpolar solutes in the interface of simple liquids are calculated as a function of the distance z from the interface. We then examine the temperature dependence of ? under two conditions: variation of ? at fixed position z and that at fixed local solvent density around the solute molecule. It is found that the temperature dependence of ? at fixed z depends on the position z and the system, whereas ? at fixed local density decreases with increasing temperature for all the model solutions at any fixed density between vapor and liquid phases. The monotonic decrease of ? under the fixed-density condition in the liquid-vapor interface is in accord with what we know for the solubility of nonpolar molecules in bulk liquid water under the fixed-volume condition but it is much robust since the solvent density to be fixed can be anything between the coexisting vapor and liquid phases. A unique feature found in the water interface is that there is a minimum in the local solubility profile ?(z) on the liquid side of the interface. We find that with decreasing temperature the minimum of ? grows and at the same time the first peak in the oscillatory density profile of water develops. It is likely that the minimum of ? is due to the layering structure of the free interface of water.

Abe, Kiharu; Sumi, Tomonari; Koga, Kenichiro

2014-11-01

214

Liquid phase temperature determination in dense water sprays using linear Raman scattering.  

PubMed

Linear Raman scattering has been applied for the determination of the temperature of the liquid phase in water sprays under normal and superheated conditions. The envelope of the Raman OH-stretching vibration band of water is deconvoluted into five Gaussian peaks which can be assigned to five different intermolecular interactions (hydrogen bonding). The intensity of each of the peaks is a function of the temperature and the phase of the water under investigation. The interference of the Raman signals originating from the water vapor is eliminated from the Raman signals originating from the liquid water. Consequently the temperature of the liquid water droplets surrounded by water vapor is accessible which is favorable for the investigation of non-equilibrium sprays where the droplet temperature is different to the vapor temperature. PMID:24718172

Hankel, Robert Fabian; Günther, Astrid; Wirth, Karl-Ernst; Leipertz, Alfred; Braeuer, Andreas

2014-04-01

215

Polarizable contributions to the surface tension of liquid water.  

PubMed

Surface tension, gamma, strongly affects interfacial properties in fluids. The degree to which polarizability affects gamma in water is thus far not well established. To address this situation, we carry out molecular dynamics simulations to study the interfacial forces acting on a slab of liquid water surrounded by vacuum using the Gaussian charge polarizable (GCP) model at 298.15 K. The GCP model incorporates both a fixed dipole due to Gaussian distributed charges and a polarizable dipole. We find a well-defined bulklike region forms with a width of approximately 31 A. The average density of the bulklike region agrees with the experimental value of 0.997 g/cm3. However, we find that the orientation of the molecules in the bulklike region is strongly influenced by the interfaces, even at a distance five molecular diameters from the interface. Specifically, the orientations of both the permanent and induced dipoles show a preferred orientation parallel to the interface. Near the interface, the preferred orientation of the dipoles becomes more pronounced and the average magnitude of the induced dipoles decreases monotonically. To quantify the degree to which molecular orientation affects gamma, we calculate the contributions to gamma from permanent dipolar interactions, induced dipolar interactions, and dispersion forces. We find that the induced dipole interactions and the permanent dipole interactions, as well as the cross interactions, have positive contributions to gamma, and therefore contribute stability to the interface. The repulsive core interactions result in a negative contribution to gamma, which nearly cancels the positive contributions from the dipoles. The large negative core contributions to gamma are the result of small oxygen-oxygen separation between molecules. These small separations occur due to the strong attractions between hydrogen and oxygen atoms. The final predicted value for gamma (68.65 m/Nm) shows a deviation of approximately 4% of the experimental value of 71.972 m/Nm. The inclusion of polarization is critical for this model to produce an accurate value. PMID:16965110

Rivera, Jose L; Starr, Francis W; Paricaud, Patrice; Cummings, Peter T

2006-09-01

216

Macroemulsions of liquid and supercritical CO{sub 2}-in-water and water-in-liquid CO{sub 2} stabilized by fine particles  

SciTech Connect

Liquid and supercritical carbon dioxide-in-water (C/W) and water-in-carbon dioxide (W/C) macroemulsions (Pickering emulsions) stabilized by fine particles were created in a high-pressure batch reactor. C/W macroemulsions form when hydrophilic particles, such as pulverized limestone, sand, flyash, shale, and lizardite, a rock rich in magnesium silicate, are used as stabilizers; W/C macroemulsions form when hydrophobic particles, such as Teflon powder, activated carbon, carbon black, and pulverized coal, are used as stabilizers. C/W macroemulsions form with both liquid and supercritical CO{sub 2}, C/W macroemulsions consist of dispersed droplets of liquid or supercritical CO{sub 2} sheathed with particles in water; W/C macroemulsions consist of droplets of water sheathed with particles dispersed in liquid CO{sub 2}. The sheathed droplets are called globules. The globule diameter is largely dependent on the shear force imparted by mixing the two fluids, CO{sub 2} and H{sub 2O. The particle size needs to be adjusted to the dispersed droplet diameter; a practical ratio was found to be 1:20. In a batch reactor with a magnetic stir bar rotating at 1300 rpm, liquid CO{sub 2} produced typical globule diameters in the 200-300 mu m range, whereas supercritical CO{sub 2} produced smaller globules, in the 100-150 mu m range.

Golomb, D.; Barry, E.; Ryan, D.; Swett, P.; Duan, H. [University of Massachusetts Lowell, Lowell, MA (United States)

2006-04-12

217

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

SciTech Connect

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.

Schiozer, A.L.

1994-03-01

218

A Fixed Point Charge Model for Water Optimized to the Vapor-Liquid Coexistence Properties  

E-print Network

@ipst.umd.edu #12;1 Abstract A new fixed-point charge potential model for water has been developed, targeting interactions in water, an intermolecular potential model valid over a broad range of densities and temperatures and their successful description of the structure of liquid water at near-ambient conditions. A Lennard-Jones potential

219

Network analysis of proton transfer in liquid water Roman Shevchuk, Noam Agmon, and Francesco Rao  

E-print Network

energy calculation for the Beckmann rearrangement promoted by proton transfers in the supercritical waterNetwork analysis of proton transfer in liquid water Roman Shevchuk, Noam Agmon, and Francesco Rao=pdfcov Published by the AIP Publishing Articles you may be interested in Faster proton transfer dynamics of water

Agmon, Noam

220

Reference Correlations for Thermophysical Properties of Liquid Water Jaroslav Ptek, Jan Hrub,a...  

E-print Network

Reference Correlations for Thermophysical Properties of Liquid Water at 0.1 MPa Jaroslav Pátek, Jan Association for the Properties of Water and Steam IAPWS . The equations presented here are simple enough capacity; speed of sound; thermal conductivity; ther- modynamic properties; viscosity; water. CONTENTS 1

Magee, Joseph W.

221

Water clusters: Untangling the mysteries of the liquid, one molecule at a time  

E-print Network

Water clusters: Untangling the mysteries of the liquid, one molecule at a time Frank N. Keutsch of small (dimer through hexamer) water clusters. These data, in conjunction with new theoretical advances and solid phases of water, including an accurate universal force field. The quest to achieve an accurate

Cohen, Ronald C.

222

Characterization of Subcritical Water as a Chromatographic Mobile Phase in Reversed-Phase Liquid Chromatography  

Microsoft Academic Search

Liquid chromatography, particularly reversed-phase liquid chromatography (RPLC), is a ubiquitous analytical method throughout various industries. It has proven vital to the regulatory framework of agencies worldwide to ensure product quality and safety. With traditional RPLC, organic modifiers (e.g. acetonitrile, methanol, tetrahydrofuran) are generally used in conjunction with water to form a mobile phase with sufficient eluotropic strength to elute analytes

Steven D. Allmon

2010-01-01

223

Elucidating the mechanism of selective ion adsorption to the liquid water surface  

E-print Network

solution to the liquid/vapor interface was measured as a function of temperature by resonant UV second and solubility, enzyme activity) (16, 17), as embodied in the famous Hofmeister series of relative lyotropic ion of temperature-dependent adsorption free energy for a prototypical inorganic ion at the liquid water surface

Cohen, Ronald C.

224

Dynamics of Isolated Water Molecules in a Sea of Ions in a Room Temperature Ionic Liquid  

E-print Network

Dynamics of Isolated Water Molecules in a Sea of Ions in a Room Temperature Ionic Liquid Daryl B2O molecules in the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium resolved in the IR absorption spectrum in spite of the fact that the D2O is surrounded by a sea of ions

Fayer, Michael D.

225

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

SciTech Connect

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.

Lundin, A. G., E-mail: arlund@mail.ru; Koryavko, N. A.; Chichikov, S. A. [Siberian State Technological University (Russian Federation)

2013-05-15

226

Ultralow liquid/solid friction in carbon nanotubes: comprehensive theory for alcohols, alkanes, OMCTS, and water.  

PubMed

In this work, we perform a theoretical study of liquid flow in graphitic nanopores of different sizes and geometries. Molecular dynamics flow simulations of different liquids (water, decane, ethanol, and OMCTS) in carbon nanotubes (CNT) are shown to exhibit flow velocities 1-3 orders of magnitude higher than those predicted from the continuum hydrodynamics framework and the no-slip boundary condition. These results support previous experimental findings obtained by several groups that reported exceptionally high liquid flow rates in CNT membranes. The liquid/graphite friction coefficient is identified as the crucial parameter for this fast mass transport in CNT. The friction coefficient is found to be very sensitive to wall curvature: friction is independent of confinement for liquids between flat graphene walls with zero curvature, whereas it decreases with increasing positive curvature (liquid inside CNT), and it increases with increasing negative curvature (liquid outside CNT). Furthermore, we present a theoretical approximate expression for the friction coefficient, which predicts qualitatively and semiquantitatively its curvature dependent behavior. The proposed theoretical description, which works well for different kinds of liquids (alcohols, alkanes, and water), sheds light on the physical mechanisms at the origin of the ultra low liquid/solid friction in CNT. In fact, it is due to their perfectly ordered molecular structure and their atomically smooth surface that carbon nanotubes are quasiperfect liquid conductors compared to other membrane pores like nanochannels in amorphous silica. PMID:22974715

Falk, Kerstin; Sedlmeier, Felix; Joly, Laurent; Netz, Roland R; Bocquet, Lydéric

2012-10-01

227

Ultrafast, Unimpeded Liquid Water Transport Through Graphene-Based Nanochannels Measured by Isotope Labelling  

E-print Network

Graphene-based laminates, with ultralong and tortuous nanocapillaries formed by simply stacking graphene flakes together, have great promises in filtration and separation. However, the information on liquid water trans-membrane permeation is lacking, which is the most fundamental problem and of crucial importance in solution-based mass transport. Here, based on isotope labelling, we investigate the liquid water transportation through graphene-based nanocapillaries under no external hydrostatic pressures. Liquid water can afford an unimpeded permeation through graphene-based nanochannels with a diffusion coefficient 4~5 orders of magnitude larger than through sub-micrometer-sized polymeric channels. When dissolving ions in sources, the diffusion coefficient of ions through graphene channels lies in the same order of magnitude as water, while the ion diffusion is faster than water, indicating that the ions are mainly transported by fast water flows and the delicate interactions between ions and nanocapillary wa...

Sun, Pengzhan; Wang, Kunlin; Zhong, Minlin; Wu, Dehai; Zhu, Hongwei

2014-01-01

228

CarParrinello molecular dynamics simulation of the calcium ion in liquid water  

E-print Network

Car­Parrinello molecular dynamics simulation of the calcium ion in liquid water Mor M. Naor, Keith computa- tional and experimental approaches, yielding a wide range of different results. Kaufman Katz et

Dellago, Christoph

229

Nuclear tanker producing liquid fuels from air and water  

E-print Network

Emerging technologies in CO? air capture, high temperature electrolysis, microchannel catalytic conversion, and Generation IV reactor plant systems have the potential to create a shipboard liquid fuel production system ...

Galle-Bishop, John Michael

2011-01-01

230

Ab initio calculation of the electronic absorption spectrum of liquid water  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

231

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

PubMed

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. PMID:24784291

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

2014-04-28

232

Far-infrared laser vibrationrotationtunneling spectroscopy of water clusters in the librational band region of liquid water  

E-print Network

clusters;7,9,11,12,14,17­20 this has afforded a rig- orous test of various water potentials and ab initio for breaking and reforming of hydrogen bonds, a salient aspect of liquid water dynamics. © 2001 American

Cohen, Ronald C.

233

Determination of Trihalomethanes in Drinking Water by Dispersive Liquid–Liquid Microextraction then Gas Chromatography with Electron-Capture Detection  

Microsoft Academic Search

Dispersive liquid–liquid microextraction (DLLME) has been used for preconcentration of trihalomethanes (THMs) in drinking\\u000a water. In DLLME an appropriate mixture of an extraction solvent (20.0 ?L carbon disulfide) and a disperser solvent (0.50 mL\\u000a acetone) was used to form a cloudy solution from a 5.00-mL aqueous sample containing the analytes. After phase separation\\u000a by centrifugation the enriched analytes in the settled phase

R. Rahnama Kozani; Y. Assadi; F. Shemirani; M. R. Milani Hosseini; M. R. Jamali

2007-01-01

234

Probing the Electron Delocalization in Liquid Water and Ice at Attosecond Time Scales  

SciTech Connect

We determine electron delocalization rates in liquid water and ice using core-hole decay spectroscopy. The hydrogen-bonded network delocalizes the electrons in less than 500 as. Broken or weak hydrogen bonds--in the liquid or at the surface of ice--provide states where the electron remains localized longer than 20 fs. These asymmetrically bonded water species provide electron traps, acting as a strong precursor channel to the hydrated electron.

Nordlund, D.; Nilsson, A. [Stanford Synchrotron Radiation Laboratory, P.O. Box 20450 Stanford, California 94309 (United States); FYSIKUM, Stockholm University, AlbaNova University Center, S-10691 Stockholm (Sweden); Ogasawara, H. [Stanford Synchrotron Radiation Laboratory, P.O. Box 20450 Stanford, California 94309 (United States); Bluhm, H. [Chemical Sciences Division, LBNL, 1 Cyclotron Road (United States); Takahashi, O. [Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Odelius, M.; Pettersson, L. G. M. [FYSIKUM, Stockholm University, AlbaNova University Center, S-10691 Stockholm (Sweden); Nagasono, M. [Department of Physics, University of Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany)

2007-11-23

235

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

NASA Astrophysics Data System (ADS)

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 (?) 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 ? 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 ?s. For olivine with the mean wavenumber of 3517 cm-1 we determined an ? 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 ? 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 ? increases with decreasing wavenumber. In case of the SiO2 system it turns out that the magnitude of ? within one structure type is independent of the liable OH point defect and therewith the wavenumber of the observed band position. Consequently, one single mean ? of 68,000±5,000 lmol-1H2Ocm-2 could be determined for a suite of quartz samples with varying OH point defects. In contrast, ? varies with the structure itself. For polymorphic coesite we calculated a different ? of 214,000±8,000 lmol-1H2O}cm-2, that is in good agreement with earlier established data [8]. Quantification data of stishovite resulted in an even higher value of ?=867,000±29,000 lmol-1H2Ocm-2, similar to that determined by [9]. First data on natural garnet give an ? value of 40,000±2,000 lmol-1H2Ocm-2, that confirms prior suggested values [10]. Our results demonstrate that not using mineral specific calibrations for quantitative water analyses in NAMs leads to overestimation of sample water concentrations, that are required for modelling the earth's deep water cycle. [1]Paterson, M. S. (1982), Bull. Min., 105, 20-29. [2]Libowitzky, E., Rossman, G. R. (1997), Am. Min., 82, 1111- 1115. [3]Rossman, G. R. (2006), Rev. Mineral., 62, 1-28. [4]Reichart et al. (2004), Science, 306, 1537-1540. [5]Thomas et al. (2006), Am. Min., 91, 467-470. [6]Bell et al. (2003), JGR, 108, (B2), 2105-2113. [7]Koch-Mueller et al. (2006), PCM, 33, 276-287. [8]Koch-Mueller et al. (2001), PCM, 28, 693-705. [9]Pawley et al. (1993), Science, 261, 1024-1026. [10]Maldener et al. (2003), PCM, 30, 337-344.

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

2007-12-01

236

Combustion characteristics of nanoaluminum, liquid water, and hydrogen peroxide mixtures  

SciTech Connect

An experimental investigation of the combustion characteristics of nanoaluminum (nAl), liquid water (H{sub 2}O{sub (l)}), and hydrogen peroxide (H{sub 2}O{sub 2}) mixtures has been conducted. Linear and mass-burning rates as functions of pressure, equivalence ratio ({phi}), and concentration of H{sub 2}O{sub 2} in H{sub 2}O{sub (l)} oxidizing solution are reported. Steady-state burning rates were obtained at room temperature using a windowed pressure vessel over an initial pressure range of 0.24 to 12.4 MPa in argon, using average nAl particle diameters of 38 nm, {phi} from 0.5 to 1.3, and H{sub 2}O{sub 2} concentrations between 0 and 32% by mass. At a nominal pressure of 3.65 MPa, under stoichiometric conditions, mass-burning rates per unit area ranged between 6.93 g/cm{sup 2} s (0% H{sub 2}O{sub 2}) and 37.04 g/cm{sup 2} s (32% H{sub 2}O{sub 2}), which corresponded to linear burning rates of 9.58 and 58.2 cm/s, respectively. Burning rate pressure exponents of 0.44 and 0.38 were found for stoichiometric mixtures at room temperature containing 10 and 25% H{sub 2}O{sub 2}, respectively, up to 5 MPa. Burning rates are reduced above {proportional_to}5 MPa due to the pressurization of interstitial spaces of the packed reactant mixture with argon gas, diluting the fuel and oxidizer mixture. Mass burning rates were not measured above {proportional_to}32% H{sub 2}O{sub 2} due to an anomalous burning phenomena, which caused overpressurization within the quartz sample holder, leading to tube rupture. High-speed imaging displayed fingering or jetting ahead of the normal flame front. Localized pressure measurements were taken along the sample length, determining that the combustion process proceeded as a normal deflagration prior to tube rupture, without significant pressure buildup within the tube. In addition to burning rates, chemical efficiencies of the combustion reaction were determined to be within approximately 10% of the theoretical maximum under all conditions studied. (author)

Sabourin, J.L.; Yetter, R.A. [The Pennsylvania State University, Department of Mechanical and Nuclear Engineering, University Park, PA 16801 (United States); Risha, G.A. [The Pennsylvania State University, Division of Business and Engineering, Altoona, PA 16601 (United States); Son, S.F. [Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907 (United States); Tappan, B.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2008-08-15

237

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

DOEpatents

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.

Shepodd, Timothy J. (Livermore, CA)

2006-02-21

238

Parameterization of atmospheric water vapor and cloud liquid water distribution using microwave radiometer profiler  

NASA Astrophysics Data System (ADS)

Water vapor is the most important carrier of energy in the atmosphere and is also the most important greenhouse gas. Its spatial and temporal distribution impacts weather and climate through a variety of processes, such as exchange of latent heat, radiative cooling and heating, cloud formation and precipitation. Clouds as a result of the condensation process also modify the radiative energy balance. A good parameterization of atmospheric water vapor and cloud liquid water distribution are thus important for modeling studies A dataset gathered over 369 days in various midlatitude sites with a microwave radiometric profiler is used to analyze the statistical distribution of tropospheric water vapor content (WVC) and liquid water content (LWC). The microwave profiler is automated, providing atmospheric sounding up to 10 km height in clear and cloudy conditions. It observes passively brightness temperature at twelve frequencies in a region of the microwave absorption spectrum. Atmospheric profiles are derived from brightness temperature, infrared, and surface meteorological observations using a neural network based on historical local radiosondes and forward radiative transfer modeling. The WVC distribution inside intervals of temperature is analyzed in clear and cloudy conditions. WVC is found to be well fitted by a Weibull distribution. The two Weibull parameters, the scale (?) and shape (k), are temperature (T) dependent. k is almost constant, around 2.6, for clear conditions. For cloudy conditions, at T < -10° C, k is close to 2.6. For T > -10° C, k displays a maximum in such a way that skewness, which is positive in most conditions, reverses at negative in a temperature region approximately centered around 0° C, i.e. at a level where the occurrence of cumulus clouds is high. Analytical ?(T) and k(T) relations are proposed. The statistical distribution of liquid water content is also studied. It is found to be well fitted by lognormal distribution. To assess how the results presented in the present paper are biased by the retrieval uncertainty, we compute the RMS error on the retrievals, by adding to each retrieved profile a Gaussian noise with zero mean and a standard deviation equal to the RMS error for each layer. The vertically integrated WV (IWV) is found to follow a Weibull distribution. Using the 15 years ECMWF (European Centre for Medium-range Weather Forecast) reanalysis meteorological database ERA 15, the Weibull parameters k and ? for the IWV distribution were calculated over the western European area, where the radiometric data were collected. The fields of k and ? values are rather homogeneous showing the validity of the assumption that this area can be considered as a single climatological entity for WVC distribution. Averaged values over the area are k = 2.5 and ? = 1.9 which compare very well with radiometric values, those are k = 2.8 and ? = 1.9. This agreement can be seen as supporting the validity of the IWV radiometric measurements. The vertically integrated LW (ILW) is found to be lognormaly distributed and agrees well when compared to ILW distribution obtained from EAR15.

Iassamen, A.; Sauvageot, H.; Youcef-Ettoumi, F.; Jeannin, N.; Ameur, S.

2009-09-01

239

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)

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.

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

1991-01-01

240

Excess entropy, Diffusivity and Structural Order in liquids with water-like anomalies  

E-print Network

The excess entropy, Se, defined as the difference between the entropies of the liquid and the ideal gas under identical density and temperature conditions, is shown to be the critical quantity connecting the structural, diffusional and density anomalies in water-like liquids. Based on simulations of silica and the two-scale ramp liquids, water-like density and diffusional anomalies can be seen as consequences of a characteristic non-monotonic density dependence of Se. The relationship between excess entropy, the order metrics and the structural anomaly can be understood using a pair correlation approximation to Se.

Ruchi Sharma; Somendra Nath Chakraborty; Charusita Chakravarty

2006-07-17

241

The accuracy of water vapor and cloud liquid determination by dual-frequency ground-based microwave radiometry  

Microsoft Academic Search

A dual frequency ground-based radiometer operating in the 1 to 1.4 cm wavelength range can provide continuous measurements of integrated water vapor and cloud liquid water. Using climato- logical data, the accuracy of the vapor and liquid determinations is estimated as a function of cloud amount. Limiting factors in the water determination are uncertainties in water vapor absorption coefficients and,

Ed R. Westwater

1978-01-01

242

Transcriptome sequencing of Eucalyptus camaldulensis seedlings subjected to water stress reveals functional single nucleotide polymorphisms and genes under selection  

PubMed Central

Background Water stress limits plant survival and production in many parts of the world. Identification of genes and alleles responding to water stress conditions is important in breeding plants better adapted to drought. Currently there are no studies examining the transcriptome wide gene and allelic expression patterns under water stress conditions. We used RNA sequencing (RNA-seq) to identify the candidate genes and alleles and to explore the evolutionary signatures of selection. Results We studied the effect of water stress on gene expression in Eucalyptus camaldulensis seedlings derived from three natural populations. We used reference-guided transcriptome mapping to study gene expression. Several genes showed differential expression between control and stress conditions. Gene ontology (GO) enrichment tests revealed up-regulation of 140 stress-related gene categories and down-regulation of 35 metabolic and cell wall organisation gene categories. More than 190,000 single nucleotide polymorphisms (SNPs) were detected and 2737 of these showed differential allelic expression. Allelic expression of 52% of these variants was correlated with differential gene expression. Signatures of selection patterns were studied by estimating the proportion of nonsynonymous to synonymous substitution rates (Ka/Ks). The average Ka/Ks ratio among the 13,719 genes was 0.39 indicating that most of the genes are under purifying selection. Among the positively selected genes (Ka/Ks > 1.5) apoptosis and cell death categories were enriched. Of the 287 positively selected genes, ninety genes showed differential expression and 27 SNPs from 17 positively selected genes showed differential allelic expression between treatments. Conclusions Correlation of allelic expression of several SNPs with total gene expression indicates that these variants may be the cis-acting variants or in linkage disequilibrium with such variants. Enrichment of apoptosis and cell death gene categories among the positively selected genes reveals the past selection pressures experienced by the populations used in this study. PMID:22853646

2012-01-01

243

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

USGS Publications Warehouse

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)

Delaney, David F.; Maevsky, Anthony

1980-01-01

244

The effect of polymorphism and magnesium substitution on oxygen isotope fractionation between calcium carbonate and water  

Microsoft Academic Search

Calcite, aragonite and magnesian calcite were slowly precipitated from aqueous bicarbonate solutions, and oxygen isotope fractionation factors between the precipitate and water were measured. For calcite-water at 25°C and 0°C, 1000 ln = 28.1 and 33.7, respectively, both values in excellent agreement with the Urey-Epstein paleotemperature scale. Aragonitewater at 25°C gave 28.7, implying a small but significant fractionation between aragonite

Toshikazu Tarutani; Robert N. Clayton; Toshiko K. Mayeda

1969-01-01

245

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

SciTech Connect

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.

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

2007-06-25

246

FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola III. Water Vapor, Liquid Water, and 183 GHz Water Vapor Line Opacities  

E-print Network

Further analysis has been made on the millimeter and submillimeter-wave (100-1600 GHz or 3 mm - 188 micron) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows good correlation with the 183 GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183 GHz line opacity show no correlation. Since only the water vapor component is expected to affect the phase of interferometers significantly, and the submillimeter-wave opacity is less affected by the liquid water component, it may be possible to use the submillimeter-wave opacity for a phase-correction of submillimeter interferometers.

Satoki Matsushita; Hiroshi Matsuo

2003-02-03

247

FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola: III. Water Vapor, Liquid Water, and 183GHz Water Vapor Line Opacities  

NASA Astrophysics Data System (ADS)

Further analysis has been made on the millimeter- and submillimeter-wave (100-1600GHz or 3mm-188 ?m) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above the sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter- and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter- and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows a good correlation with the 183GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183GHz line opacity show no correlation. S ince only the water vapor component is expected to affect the phase of interferometers significantly, and the submillimeter-wave opacity is less affected by the liquid water component, it may be possible to use the submillimeter-wave opacity for a phase correction of submillimeter interferometers.

Matsushita, Satoki; Matsuo, Hiroshi

2003-02-01

248

Interpreting the H/D Isotope Fractionation of Liquid Water DuringEvaporation Without Condensation  

SciTech Connect

A theoretical model of liquid water evaporation has been developed to interpret results from a recent experimental investigation of isotope fractionation during free evaporation. It is established that the free evaporation isotope fractionation factors ({alpha}{sub evap}) are primarily influenced by the nature of the intermolecular interactions between water molecules, namely, the condensed phase hindered translational and librational frequencies at the surface. The dependence of {alpha}{sub evap} on the isotopic composition of the liquid can be understood in terms of small variations in these frequencies with isotopic composition. This result suggests that the explicit nature of the solvation environment directly influences evaporation rates from liquids. The sensitivity of the calculated evaporation coefficient for liquid water to both temperature and isotope composition is also explored.

Cappa, Christopher D.; Smith, Jared D.; Drisdell, Walter S.; Saykally, Richard J.; Cohen, Ronald C.

2007-03-15

249

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

NASA Technical Reports Server (NTRS)

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.

Stoker, C.

2004-01-01

250

Thermal signature reduction through liquid nitrogen and water injection  

E-print Network

. The research efforts investigated two approaches to shield the thermal signature of the Noel Penny Type 401 turbojet at the Texas A&M University Propulsion Lab Test Cell. First, liquid nitrogen was injected through a manifold at a flow rate equivalent...

Guarnieri, Jason Antonio

2005-02-17

251

Retrieving Liquid Water Path and Precipitable Water Vapor from the Atmospheric Radiation Measurement (ARM) Microwave Radiometers  

SciTech Connect

Ground-based two-channel microwave radiometers have been used for over 15 years by the Atmospheric Radiation Measurement (ARM) program to provide observations of downwelling emitted radiance from which precipitable water vapor (PWV) and liquid water path (LWP) – twp geophysical parameters critical for many areas of atmospheric research – are retrieved. An algorithm that utilizes two advanced retrieval techniques, a computationally expensive physical-iterative approach and an efficient statistical method, has been developed to retrieve these parameters. An important component of this Microwave Retrieval (MWRRET) algorithm is the determination of small (< 1K) offsets that are subtracted from the observed brightness temperatures before the retrievals are performed. Accounting for these offsets removes systematic biases from the observations and/or the model spectroscopy necessary for the retrieval, significantly reducing the systematic biases in the retrieved LWP. The MWRRET algorithm provides significantly more accurate retrievals than the original ARM statistical retrieval which uses monthly retrieval coefficients. By combining the two retrieval methods with the application of brightness temperature offsets to reduce the spurious LWP bias in clear skies, the MWRRET algorithm provides significantly better retrievals of PWV and LWP from the ARM 2-channel microwave radiometers compared to the original ARM product.

Turner, David D.; Clough, Shepard A.; Liljegren, James C.; Clothiaux, Eugene E.; Cady-Pereira, Karen E.; Gaustad, Krista L.

2007-11-01

252

Spectrally resolved Raman lidar measurements of gaseous and liquid water in the atmosphere.  

PubMed

A spectrally resolved Raman lidar based on a tripled Nd:YAG laser is built for measuring gaseous and liquid water in the atmosphere. A double-grating polychromator with a reciprocal linear dispersion of ~0.237 nm mm(-1) is designed to achieve the wavelength separation and the suppression of elastic backscatter. A 32-channel linear-array photomultiplier tube is employed to sample atmospheric Raman water spectrum between 401.65 and 408.99 nm. The lidar-observed Raman water spectrum in the very clear atmosphere is nearly invariable in shape. It is dominated by water vapor, and can serve as background reference for Raman lidar identification of the phase state of atmospheric water under various weather conditions. The lidar has measured also the Raman water spectrum of an aerosol/liquid water layer. The spectrum showed a moderate increase of the signal on both sides of the Q-branch of water vapor. Noting that under clear weather conditions the Raman water spectrum intensity stays at a very low level in the 401.6-404.7 nm range, the Raman water signal in this portion can be used to estimate the liquid water content in the layer. PMID:24085202

Liu, Fuchao; Yi, Fan

2013-10-01

253

Development of liquid and gas chromatographic methods for the determination of water.  

National Technical Information Service (NTIS)

Two liquid chromatographic (LC) methods and one gas chromatographic (GC) method for the determination of water are developed. In the LC methods, water in various analytical samples is separated from the sample matrices on either a single cation-exchange c...

J. Chen

1991-01-01

254

Hydrogen Isotope Separation by Catalyzed Exchange Between Hydrogen and Liquid Water  

Microsoft Academic Search

The discovery, at Chalk River Nuclear Laboratories, of a simple method of wetproofing platinum catalysts so that they retain their activity in liquid water stimulated a concentrated research program for the development of catalysts for the hydrogen-water isotopic exchange reaction. This paper reviews 10 years of study which have resulted in the development of highly active platinum catalysts which remain

J. P. Butler

1980-01-01

255

Quantum Effects in Water: Proton Kinetic Energy Maxima in Stable and Supercooled Liquid  

Microsoft Academic Search

A strong temperature dependence of proton mean kinetic energy was observed for liquid water around the density maximum and for moderately supercooled water. Line shape analysis of proton momentum distribution, determined from deep inelastic neutron scattering measurements, shows that there are two proton kinetic energy maxima, one at the same temperature of the macroscopic density maximum at 277 K, and

Antonino Pietropaolo; Roberto Senesi; Carla Andreani; Jerry Mayers

2009-01-01

256

A two-dimensional computational model of a PEMFC with liquid water transport  

Microsoft Academic Search

A comprehensive, steady-state, computational model of a proton exchange membrane fuel cell (PEMFC) derived from first principles is presented. The model is two-dimensional and includes the transport of liquid water within the porous electrodes as well as the transport of gaseous species, protons, energy, and water dissolved in the ion conducting polymer. Electrochemical kinetics are modeled with standard rate equations

N. P. Siegel; M. W. Ellis; D. J. Nelson; M. R. von Spakovsky

2004-01-01

257

LETTER TO THE EDITOR: Spectroscopic probing of local hydrogen-bonding structures in liquid water  

Microsoft Academic Search

We have studied the electronic structure of liquid water using x-ray absorption spectroscopy at the oxygen K edge. Since the x-ray absorption process takes less than a femtosecond, it allows probing of the molecular orbital structure of frozen, local geometries of water molecules at a timescale that has not previously been accessible. Our results indicate that the electronic structure of

S. Myneni; Y. Luo; L. Å. Näslund; M. Cavalleri; L. Ojamäe; H. Ogasawara; A. Pelmenschikov; Ph Wernet; P. Väterlein; C. Heske; Z. Hussain; L. G. M. Pettersson; A. Nilsson

2002-01-01

258

FEATURE ARTICLE Investigations of the Structure and Hydrogen Bonding of Water Molecules at Liquid  

E-print Network

FEATURE ARTICLE Investigations of the Structure and Hydrogen Bonding of Water Molecules at Liquid, 1998 The structure and hydrogen bonding of water molecules provides this unique solvent with properties essential to many physical, chemical, and biological processes. The intermolecular hydrogen bonding between

Richmond, Geraldine L.

259

Molecular dynamics studies of the liquid-vapor interface of water  

NASA Astrophysics Data System (ADS)

We report the results of molecular dynamics simulations of the liquid-vapor interface of water. Two different water-water interactions were studied. The density profile of the interfacial transition region between liquid and vapor is monotone with a 10%-90% width of 3.45 Å, in good agreement with the value determined from x-ray reflectance measurements, namely 3.30 Å. The water molecules in the interface tend to lie with the HOH bisector in the plane of the surface and one OH bond pointing out of the surface. As the density falls in the transition region the tetrahedral structure of the bulk liquid breaks up and there is a tendency towards dimerization. The diffusion constant in the interfacial region is 58% larger than that in the bulk region.

Townsend, R. Michael; Rice, Stuart A.

1991-02-01

260

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

SciTech Connect

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.

Tailor, Ramesh; Ibbott, Geoffrey; Lampe, Stephanie; Bivens Warren, Whitney; Tolani, Naresh [Radiation Physics, UT MD Anderson Cancer Center, 1515 Holcombe Boulevard, Box 94, Houston, Texas 77030 (United States); Radiological Physics Center, UT M.D. Anderson Cancer Center, 7515 Main Street, Suite 300, Houston, Texas 77030-4519 (United States); Radiation Physics, M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Box 94, Houston, Texas 77030 (United States); Harrington Cancer Center, 1500 Wallace Boulevard, Amarillo, Texas 76106 (United States); Radiation Physics, U.T. M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Box 94, Houston, Texas 77030 (United States)

2008-12-15

261

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

NASA Astrophysics Data System (ADS)

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.

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

1997-06-01

262

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

SciTech Connect

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.

Mok, Y.S.; Lee, W.K. (Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of))

1994-03-01

263

[Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization].  

PubMed

To achieve accurate, fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples, a method of dispersive liquid-liquid microextraction (DLLME) coupled with fluorescent derivatization was developed for the determination of bisphenol A, nonylphenol, octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The DLLME and derivatization conditions were investigated, and the optimized DLLME conditions for small volume of environmental water samples (pH 4.0) at room temperature were as follows: 70 microL chloroform as extraction solvent, 400 microL acetonitrile as dispersing solvent, vortex mixing for 3 min, and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo [a, g] carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as precolumn derivatization reagent, the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10.5 Na2CO3-NaHCO3 buffer/acetonitrile at 50 degrees C for 3 min, and then separated within 10 min by HPLC-FLD. The limits of detection (LODs) were in the range of 0.9-1.6 ng/L, and the limits of quantification (LOQs) were in the range of 3.8-7.1 ng/L. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing to the previously reported methods. It is a convenient and validated method for the routine analysis of phenolic endocrine disruptors in waste water of paper mill, lake water, domestic wastewater, tap water, etc. PMID:25269261

Wang, Xiaoyan; Qi, Weimei; Zhao, Xian'en; Lü, Tao; Wang, Xiya; Zheng, Longfang; Yan, Yehao; You, Jinmao

2014-06-01

264

Ionic liquid based dispersive liquid-liquid microextraction coupled with micro-solid phase extraction of antidepressant drugs from environmental water samples.  

PubMed

Ionic liquid-dispersive liquid-liquid microextraction combined with micro-solid phase extraction (IL-DLLME-?-SPE), and high-performance liquid chromatography (HPLC) was developed for the determination of tricyclic antidepressants (TCAs) in water samples. Two hundred microliters of an organic solvent (as disperser solvent) and 20 ?l of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate were injected into a 5.0 ml sample for sonication-assisted DLLME. After this, a ?-SPE device, containing a novel material zeolite imidazolate framework 4 (ZIF-4), was added into the sample solution and 1 min of vortex-assisted extraction was performed. After 5 min of sonication-assisted desorption, 10 ?l of desorption solvent was injected into a HPLC system for analysis. A characteristic property of DLLME-VA-?-SPE is that any organic solvent and solid sorbent immiscible with water can be used. Special apparatus, or conical-bottom test tubes, and tedious procedures conventionally associated with DLLME such as centrifugation, or refrigeration of solvent are not necessary in the present approach. A novel material, ZIF-4 was employed as ?-SPE sorbent. Under the optimized conditions, the calibration curves were linear in the range of 1-1000 ?g/L. The relative standard deviations and the limits of detection were in the range of 1.5% and 7.8% and 0.3 and 1 ?g/L, respectively. The relative recoveries of canal water samples, spiked with drugs, were in the range of 94.3% and 114.7%. The results showed that IL-DLLME-?-SPE was suitable for the determination of TCAs in water samples. PMID:23639124

Ge, Dandan; Lee, Hian Kee

2013-11-22

265

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

266

Dispersive liquid-liquid microextraction with non-halogenated extractants for trihalomethanes determination in tap and swimming pool water.  

PubMed

An effective, low solvent consumption, reduced cost and high throughput sample preparation method for the determination of four trihalomethanes (THMs) in tap and swimming pool water samples is presented. THMs extraction and concentration were performed by dispersive liquid-liquid microextraction (DLLME), based on the use of non-halogenated and low volatile solvents as extractants. Analytes were further determined by gas chromatography with micro-electron capture detection (GC-microECD). Under optimized conditions, the proposed method uses 18 mL volume samples, 0.7 mL of acetone (dispersant) and 0.05 mL of 1-undecanol (extractant). Achieved enrichment factors (EFs) varied from 67 to 104 times, the limits of quantification (LOQs) stayed between 0.05 and 1.3 ng mL(-1), and an excellent linearity was noticed up to 100 ng mL(-1). Relative recoveries, measured for spiked aliquots of tap and swimming pool water samples, remained between 79% and 113%, with associated standard deviations below 12%. The applicability of the developed methodology was demonstrated with chlorinated water samples analysis. As regards tap water samples, the sum of THMs concentrations remained under the limit fixed by the European Union (100 ng mL(-1)); however, some samples contained levels close to 80 ng mL(-1), the maximum allowable concentration established by the United States Environmental Protection Agency (EPA). PMID:22967632

Rodríguez-Cabo, T; Ramil, M; Rodríguez, I; Cela, R

2012-09-15

267

A dispersive liquid-liquid microextraction procedure for determination of boron in water after ultrasound-assisted conversion to tetrafluoroborate.  

PubMed

A novel, simple and green procedure is presented for the determination of boron. The method is based on ultrasound-assisted conversion of boron to tetrafluoroborate anion and the formation of an ion pair between BF(4)(-) and Astra Phloxine reagent (R), followed by dispersive liquid-liquid microextraction of the ion pair formed and subsequent UV-vis spectrophotometric detection. The conversion of boron to tetrafluoroborate anion is performed in an acidic medium of 0.9 mol L(-1) H(2)SO(4) in the presence of 0.1 mol L(-1)F(-) by means of 10 min of ultrasonication. The extraction of the ion pair formed between BF(4)(-) and R (1×10(-4)mol L(-1)R) is carried out by dispersive liquid-liquid microextraction using 0.5 mL of amyl acetate (as extraction solvent), tetrachloromethane (as auxiliary solvent) and acetonitrile (as dispersive solvent) in a ratio of 1:1:2. The absorbance of the coloured extracts obeys Beer's law in the range 0.22-18.7 mg L(-1) of B(III) at 553 nm wavelength. The limit of detection calculated from a blank test (n=10) based on 3s is 0.015 mg L(-1) of B(III). The method was applied to the determination of boron in mineral waters. PMID:21645738

Rusnáková, Lenka; Andruch, Vasil; Balogh, Ioseph S; Skrlíková, Jana

2011-07-15

268

Growth of the calcium carbonate polymorph vaterite in mixtures of water and ethylene glycol at conditions of gas processing  

NASA Astrophysics Data System (ADS)

Long subsea tie-ins for transportation of moist gas and condensate require corrosion and hydrate control. The combination of alkalinity for corrosion mitigation and monoethylene glycol (MEG) for hydrate inhibition strongly affects the tolerance for produced formation water. The elevated alkalinity downstream of the injection point increases the risk of carbonate formation. Calcium carbonate is the most common precipitate at such conditions. Our previous findings (Flaten et al., 2009) [1] show that MEG governs calcium carbonate precipitation and promotes formation of the metastable polymorph vaterite. This paper describes crystal growth of vaterite in mixed MEG water solvent with 0-70 wt% MEG at temperatures of 40 and 70 °C in solutions with high calcium to carbonate ratios representative of the production conditions. Results of some experiments in solutions with stoichiometric amounts of the reactants are included for comparison. The growth rate of vaterite can be described by second-order kinetics in most of the investigated supersaturation range. The growth order is lower at high MEG contents and high calcium concentrations when the carbonate activity is reduced in order to maintain comparable supersaturation values. It is then probable that the low carbonate activity makes the reaction diffusion limited. MEG reduces the growth rate constant of vaterite when the reaction is second order. Increasing the MEG concentration from 0 to 50 wt%, decreases the growth rate constant kr from 1.9 to 0.7 nm/s at 40 °C and from 2.6 to 1.2 nm/s at 70 °C. The growth reduction can be explained by a change of either de-hydration or diffusion rate along the surface when the ions are incorporated into the crystal lattice. Further investigations into which of the two mechanisms that is rate determining is outside the scope of this work.

Flaten, Ellen Marie; Seiersten, Marion; Andreassen, Jens-Petter

2010-03-01

269

Evidence for an Enhanced Hydronium Concentration at the Liquid Water Surface Poul B. Petersen and Richard J. Saykally*  

E-print Network

Evidence for an Enhanced Hydronium Concentration at the Liquid Water Surface Poul B. Petersen embodies both the surface tension increase measured for salt solutions relative to pure water3 concentration of "soft" anions (e.g., I-) at the outermost layer of the liquid water surface. In this case

Cohen, Ronald C.

270

A systematic experimental study of rapidly rotating spherical convection in water and liquid gallium  

Microsoft Academic Search

Results of finite-amplitude convection experiments in a rotating spherical shell are presented. Water (Prandtl number P=7) and liquid gallium (P=0.027) have been used as working fluids. In both liquids, convective velocities could be measured in the equatorial plane using an ultrasonic Doppler velocimetry technique. The parameter space has been systematically explored, for values of the Ekman and Rayleigh numbers E>7×10?7

Julien Aubert; Daniel Brito; Henri-Claude Nataf; Philippe Cardin; Jean-Paul Masson

2001-01-01

271

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

SciTech Connect

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.

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

1981-02-01

272

Interfacial Depth Profiling of the Orientation and Bonding of Water Molecules across Liquid-Liquid Interfaces  

E-print Network

Molecular interactions that create the interfacial properties present at a junction between water the simplest type of halocarbon, yet each molecule possesses unique physical properties that enable clear. As a result, there is considerable interest in understanding the structural properties of water within

Richmond, Geraldine L.

273

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

SciTech Connect

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.

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

2008-02-16

274

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

SciTech Connect

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.

Brusseau, M.L.; Narter, M.; Schnaar, G.; Marble, J.; (Ariz)

2009-06-01

275

Application of response surface methodology for optimization of ionic liquid-based dispersive liquid-liquid microextraction of cadmium from water samples.  

PubMed

A new, rapid, and simple method for the determination of cadmium in water samples was developed using ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) coupled to flame atomic absorption spectrometry (FAAS). In the proposed approach, 2-(5-boromo-2-pyridylazo)-5-(diethyamino) phenol was used as a chelating agent and 1-hexyl-3-methylimidazolium bis(trifluoro methylsulfonyl)imide and acetone were selected as extraction and dispersive solvents, respectively. Sample pH, concentration of chelating agent, amount of ionic liquid (extraction solvent), disperser solvent volume, extraction time, salt effect, and centrifugation speed were selected as interested variables in IL-DLLME process. The significant variables affecting the extraction efficiency were determined using a Placket-Burman design. Thereafter, the significant variables were optimized using a Box-Behnken design and the quadratic model between the dependent and the independent variables was built. The optimum experimental conditions obtained from this statistical evaluation included: pH: 6.7; concentration of chelating agent: 1.1 10(-) (3) mol L(-1); and ionic liquid: 50.0 mg. Under the optimum conditions, the preconcentration factor obtained was 100. Calibration graph was linear in the range of 0.2-60 µg L(-1) with correlation coefficient of 0.9992. The limit of detection was 0.06 µg L(-) (1), which is lower than other reported approaches applied to the determination of cadmium using FAAS. The relative SD (n = 8) was 2.4%. The proposed method was successfully applied to the determination of trace amounts of cadmium in the real water samples with satisfactory results. PMID:22893353

Rajabi, M; Kamalabadi, M; Jamali, M R; Zolgharnein, J; Asanjarani, N

2013-06-01

276

The Association of Liquid Water Springs With Permafrost Regions on Earth and Mars  

NASA Astrophysics Data System (ADS)

Recent space missions have confirmed the presence of ice-rich ground in the middle and high latitudes of Mars. Geologically recent gully features on Mars show a geographic distribution that is correlated with theoretical models of ground ice stability which is suggestive of a genetic relationship between ground ice and gully activity. Possible mechanisms of gully formation are thus examined. A liquid water aquifer on Mars activated by freezing cycles is the favored model of gully formation based on an analysis of Mars Global Surveyor spacecraft data. Additionally, liquid water spring activity occurs in regions of continuous permafrost on Earth. Spring systems in the Canadian High Arctic (Axel Heiberg Island) as well as the Norwegian Arctic (Spitsbergen) demonstrate different morphologies and mechanisms of formation for spring systems in polar desert environments. On both Earth and Mars, liquid water springs in permafrost regions provide a unique setting for the possible preservation of biological signatures.

Heldmann, J. L.; Mellon, M. T.; Pollard, W. H.; Andersen, D. T.; McKay, C. P.

2003-12-01

277

FTS Measurements of Submillimeter-Wave Atmospheric Opacity at Pampa la Bola III. Water Vapor, Liquid Water, and 183 GHz Water Vapor Line Opacities  

E-print Network

Further analysis has been made on the millimeter and submillimeter-wave (100-1600 GHz or 3 mm - 188 micron) atmospheric opacity data taken with the Fourier Transform Spectrometer (FTS) at Pampa la Bola, 4800 m above sea level in northern Chile, which is the site of the Atacama Large Millimeter/submillimeter Array (ALMA). Time-sequence plots of millimeter and submillimeter-wave opacities show similar variations to each other, except for during the periods with liquid water (fog or clouds) in the atmosphere. Using millimeter and submillimeter-wave opacity correlations under two conditions, which are affected and not affected by liquid water, we succeeded to separate the measured opacity into water vapor and liquid water opacity components. The water vapor opacity shows good correlation with the 183 GHz water vapor line opacity, which is also covered in the measured spectra. On the other hand, the liquid water opacity and the 183 GHz line opacity show no correlation. Since only the water vapor component is expec...

Matsushita, S; Matsushita, Satoki; Matsuo, Hiroshi

2003-01-01

278

Formation of Martian Gullies by the Action of Liquid Water Flowing Under Current Martian Environmental Conditions  

NASA Technical Reports Server (NTRS)

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.

Heldmann, J. L.; Toon, O. B.; Pollard, W. H.; Mellon, M. T.; Pitlick, J.; McKay, C. P.; Andersen, D. T.

2005-01-01

279

Bubbles in liquids with phase transition. Part 1. On phase change of a single vapor bubble in liquid water  

NASA Astrophysics Data System (ADS)

In the forthcoming second part of this paper a system of balance laws for a multi-phase mixture with many dispersed bubbles in liquid is derived where phase transition is taken into account. The exchange terms for mass, momentum and energy explicitly depend on evolution laws for total mass, radius and temperature of single bubbles. Therefore in the current paper we consider a single bubble of vapor and inert gas surrounded by the corresponding liquid phase. The creation of bubbles, e.g. by nucleation is not taken into account. We study the behavior of this bubble due to condensation and evaporation at the interface. The aim is to find evolution laws for total mass, radius and temperature of the bubble, which should be as simple as possible but consider all relevant physical effects. Special attention is given to the effects of surface tension and heat production on the bubble dynamics as well as the propagation of acoustic elastic waves by including slight compressibility of the liquid phase. Separately we study the influence of the three phenomena heat conduction, elastic waves and phase transition on the evolution of the bubble. We find ordinary differential equations that describe the bubble dynamics. It turns out that the elastic waves in the liquid are of greatest importance to the dynamics of the bubble radius. The phase transition has a strong influence on the evolution of the temperature, in particular at the interface. Furthermore the phase transition leads to a drastic change of the water content in the bubble. It is shown that a rebounding bubble is only possible, if it contains in addition an inert gas. In Part 2 of the current paper the equations derived are sought in order to close the system of equations for multi-phase mixture balance laws for dispersed bubbles in liquids involving phase change.

Dreyer, Wolfgang; Duderstadt, Frank; Hantke, Maren; Warnecke, Gerald

2012-11-01

280

Rheological properties of ammonia-water liquids and crystal-liquid slurries - Planetological applications  

NASA Technical Reports Server (NTRS)

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.

Kargel, J. S.; Croft, S. K.; Lunine, J. I.; Lewis, J. S.

1991-01-01

281

Droplet size distribution and liquid volume concentration in a water spray: Predictions and measurements  

NASA Astrophysics Data System (ADS)

A water spray, from a twin fluid atomizer, was studied at different air temperatures and at atmospheric pressure. The Sauter Mean Diameter, D sub 32, and the droplet volume distribution were measured at four different distances from the injector. An optical method was used to measure droplet sizes. Predictions of the Sauter Mean Diameter, liquid volume concentration and droplet size distribution were also evaluated. The influence of the air velocity, air temperature and of the water flow rate in the spray S.M.D. and in the liquid volume concentration at different distances from the injector have been measured. The predictions showed good agreement with experimental results.

Pita, G. P.

1984-01-01

282

MEASUREMENTS AND MODEL ESTIMATES ON LIQUID WATER MASS FROM SINGLE AND MIXED-SALT PARTICLES  

Microsoft Academic Search

Aerosol liquid water mass is measured using the method developed by Lee and Hsu (1) in this work. The measured humidographs of NaCl, Na2SO4, MgCl2 · 6H2O and various NaCl-Na2SO4 and NaCl-MgCl2 · 6H2O mixed salts are reported. The results show the liquid water mass (LWM) measurements on single salts of NaCl and Na2SO4 agree with Tang et al. (2-3)

Chung-Te Lee; Shih-Yu Chang; Wen-Chuan Hsu

2004-01-01

283

Heating-induced glass-glass and glass-liquid transformations in computer simulations of water  

NASA Astrophysics Data System (ADS)

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, both being associated with the limit of kinetic stability of LDA (HDA).

Chiu, Janet; Starr, Francis W.; Giovambattista, Nicolas

2014-03-01

284

Heating-induced glass-glass and glass-liquid transformations in computer simulations of water.  

PubMed

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, both being associated with the limit of kinetic stability of LDA (HDA). PMID:24655190

Chiu, Janet; Starr, Francis W; Giovambattista, Nicolas

2014-03-21

285

Liquid-solid transition of confined water in silica-based mesopores.  

PubMed

Cooling and heating curves of water confined in partially filled Vycor porous glass were measured for both adsorption and desorption processes. One endothermic and two exothermic peaks were observed for almost all cases. The peak temperature and the enthalpy of the exothermic peak located below 232 K increased initially and then decreased with further increases in the filling factor. These abnormal changes were analyzed based on the liquid-solid transition of nanoconfined water using a core/shell model, and the initial adsorption process of water in this typical mesoporous material with disordered pores is discussed. In addition, an interesting observation is that different peak temperatures for the endothermic peak and an almost constant peak temperature for the exothermic peak were observed at the same filling factor obtained under different sample preparation conditions, that is, adsorption and desorption processes. To compare with the liquid-solid transition temperatures of confined water in fully filled silica-based mesopores of different pore radius, a parameter of the ratio of pore inner surface area to confined liquid volume is proposed in this paper. Referring to this parameter, the core part of confined water in silica-based nanopores has the same liquid-solid transition temperatures. This suggestion is valid for the freezing process of water confined in either fully filled ordered or fully or partially filled disordered pores. For the melting process, different linear changes of melting temperature with the ratio of pore inner surface area to liquid volume were observed for water in disordered and ordered pores. PMID:20205437

Liu, Xiao X; Wang, Qiang; Huang, Xiu F; Yang, Su H; Li, Chen X; Niu, Xiao J; Shi, Qin F; Sun, Gang; Lu, Kun Q

2010-04-01

286

Thrust Performance Improvement for a Water/Liquid Nitrogen Rocket Engine  

NASA Astrophysics Data System (ADS)

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.

Watanabe, Rikio; Mikami, Ryo

287

Surface Transformations and Water Uptake on Liquid and Solid Butanol near the Melting Temperature  

E-print Network

Water interactions with organic surfaces are of central importance in biological systems and many Earth system processes. Here we describe experimental studies of water collisions and uptake kinetics on liquid and solid butanol from 160 to 200 K. Hyperthermal D2O molecules (0.32 eV) undergo efficient trapping on both solid and liquid butanol, and only a minor fraction scatters inelastically after an 80% loss of kinetic energy to surface modes. Trapped molecules either desorb within a few ms, or are taken up by the butanol phase during longer times. The water uptake and surface residence time increase with temperature above 180 K indicating melting of the butanol surface 4.5 K below the bulk melting temperature. Water uptake changes gradually across the melting point and trapped molecules are rapidly lost by diffusion into the liquid above 190 K. This indicates that liquid butanol maintains a surface phase with limited water permeability up to 5.5 K above the melting point. These surface observations are indic...

Papagiannakopoulos, Panos; Thomson, Erik S; Markovic, Nikola; Pettersson, Jan B C

2013-01-01

288

Combined Microwave Radiometer and Micro Rain Radar Analysis of Cloud Liquid Water  

NASA Astrophysics Data System (ADS)

The cloud liquid water is a parameter of vital interest in both modeling and forecasting weather. In meso- scale models, the magnitude of latent heat effects corresponds to the amount of cloud liquid water, which is important in the development of a certain weather system. The purpose of this study is to obtain the combined cloud liquid water from a 21.8 and 31.4 GHz ground based microwave radiometer (MWR) and the micro rain radar (MRR), because each instrument has the limitation of observation; it is widely known that the measurements of MWR and MRR are not meaningful with and without rainfall, respectively. The cloud liquid water of the two instruments has been measured at the Cloud Physics Observation System (CPOS) site, located at 37.41¢¥ N, 128.45¢¥ E and 842 m from mean sea level. To examine the performance of instruments, the precipitable water vapor (PWV) measured by the MWR was compared with the calculated PWV of nearest radiosonde from December 2003 to July 2008, and MRR was compared with the several accumulated precipitation observed by AWS. The PWV of MWR gives good agreement with that of radiosonde: R-square = 0.82 for spring, 0.78 for summer, 0.83 for fall, but 0.25 for winter. This bad performance in the winter season seems from the heavy snow on the radome, and then the winter data of MWR has been not considered in the combining algorithm. The comparison of MRR and AWS a correlation coefficient: 30min accumulated precipitation was R-square = 0.84. To combine the MRR and MWR cloud liquid water, firstly we estimate the cloud physical thickness from the difference between the MTSAT-1R cloud top height and cloud base height of visual observation of Daegwallyeong weather station, and the cloud liquid water path of MRR is obtained by multiplying the LWC of MRR and the estimated cloud physical thickness. The trend of MWR liquid water path agrees with that of the MRR during small precipitation. We study these characteristics of MRR and MWR for small precipitation to obtain the combined cloud water content of MRR and MWR, constantly operated regardless to the rainfall.

Yang, H.; Chang, K.; Jeong, J.; Lee, S.; Jang, Y.; Lee, M.; Kim, K.

2008-12-01

289

Comment on "Structure and dynamics of liquid water on rutile TiO2(110)  

SciTech Connect

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.

Wesolowski, David J [ORNL; Sofo, Jorge O. [Pennsylvania State University; Bandura, Andrei V. [St. Petersburg State University, St. Petersburg, Russia; Zhang, Zhan [Argonne National Laboratory (ANL); Mamontov, Eugene [ORNL; Predota, M. [University of South Bohemia, Czech Republic; Kumar, Nitin [ORNL; Kubicki, James D. [Pennsylvania State University; Kent, Paul R [ORNL; Vlcek, Lukas [ORNL; Machesky, Michael L. [Illinois State Water Survey, Champaign, IL; Fenter, Paul [Argonne National Laboratory (ANL); Cummings, Peter T [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Skelton, A A [Vanderbilt University; Rosenqvist, Jorgen K [ORNL

2012-01-01

290

Estimating the lunar mantle water budget from phosphates: Complications associated with silicate-liquid-immiscibility  

NASA Astrophysics Data System (ADS)

The discovery of water within the lunar mantle has broad implications for the formation of the Earth-Moon system, differentiation of the Moon, and the magmatic evolution of lunar basalts, as well as the highland rocks. Recently, there has been considerable interest in using combined water abundances and H-isotope systematics of lunar apatites from mare basalts to quantify the origin and extent of water within the Moon's mantle. However, the petrologic and geochemical conditions that govern apatite crystallization are not well-constrained, especially for high-FeO basaltic melts that crystallize at fO2 values below the iron-wüstite buffer. Apatites are typically located within the late-stage interstitial regions. In this contribution, we present detailed textural descriptions of late-stage inter-cumulus, residual-liquid pockets (i.e., mesostasis pockets), in order to understand the petrogenesis of lunar apatite. Results from five mare basalts demonstrate that the majority of the residual liquids in mesostasis regions have undergone silicate-liquid immiscibility (SLI) splitting into Si-K-rich (felsic) and Fe-rich (Fe-basaltic) conjugate liquids. We demonstrate the complexity of these residual liquids by documenting a wide range of water contents for apatites in several mesostasis pockets within a single mare basalt, a complexity common to many basalts. These data illustrate that individual apatite-hosting mesostasis pockets behave as independent sub-systems, even within a single rock. Furthermore, we present water concentrations for another phosphate phase, merrillite, indicating additional uncertainties during considerations of water partitioning into apatite. Fractional crystallization trends have been used in order to assess the conditions under which magmas are likely to undergo SLI. Predicted liquid lines of descent indicate that it is the late-stage residual liquids of lunar basalts with relatively low-Mg# (e.g., liquid field during crystallization, forming conjugate liquids that are chemically and mineralogically distinct. However, residual liquids for basaltic magmas with high-Mg# (e.g., >?50) may not intersect the two-liquid field depending upon the fractionation trends in the late-stage mesostasis pockets. For samples that undergo SLI, the apatite/melt-partition coefficients required for back-calculating water abundances of the parental melts are compromised by the generation of two populations of apatites-merrillites from conjugate immiscible liquids. This process highlights an important complexity inherent to all water back-calculations that use apatite, as this requires an additional set of partition coefficients. We emphasize that the complex petrologic nature and common development of SLI of apatite-bearing, late-stage mesostasis pockets have not been considered in published apatite-volatile data. These factors, in additional to other considerations, illustrate why water back-calculations to model the primary melts from such data must be viewed with caution.

Pernet-Fisher, J. F.; Howarth, G. H.; Liu, Y.; Chen, Y.; Taylor, L. A.

2014-11-01

291

Obtaining of gas, liquid, and upgraded solid fuel from brown coals in supercritical water  

NASA Astrophysics Data System (ADS)

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.

Vostrikov, A. A.; Fedyaeva, O. N.; Dubov, D. Yu.; Shishkin, A. V.; Sokol, M. Ya.

2013-12-01

292

Increased radon detection sensitivity: extraction from 200 ml of water and liquid scintillation counting.  

PubMed

To increase detection sensitivity in a radon ground-water monitoring program, radon is extracted and transferred from 200 mL of water to a liquid scintillator by bubbling and circulating air through the two liquids in a closed system using a peristaltic pump. This results in a count rate that is 11 times higher than for samples prepared by the most widely used method, where 10 mL of water are added to 10 mL of scintillator. Preparation of counting samples is simple and takes 4 min. Standard deviation in radon concentration is 5% and minimum detectable activity is 5 mBq L(-1), using a counter with a background of 3 counts per hour and a counting time of 3 h. This method is also suitable for the measurement of radium in water. PMID:14571994

Theodorsson, P; Gudjonsson, G I

2003-11-01

293

Protein denaturation described by a two-state structural model of liquid water.  

PubMed

Our laboratory has been involved in expounding an outer neighbor molecular-level structural theory for liquid water in the supercooled and ordinary thermodynamic regimes. This theory, which depends on transformations with increasing temperature or pressure, is consistent with all the properties of this substance, including the ten or so "anomalies", and has been recently used to explain the effect that surrounding water has on proteins. For example, the sharp decrease in the hydration entropies of polar groups can be explained through a consideration of the promotion of ice-Ih-type bonding structure at the expense of the less stable ice-II-type bonding structure. These structural transformations occur in the local neighborhood of the polar group. In this paper we discuss this outer neighbor two-state structural theory for liquid water, the role it plays in explaining water's anomalous properties and its description of protein denaturation both as a function of temperature and pressure. PMID:11728091

Robinson, G W; Urquidi, J; Singh, S; Cho, C H

2001-07-01

294

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

Code of Federal Regulations, 2013 CFR

... false What solid and liquid wastes and discharges information and cooling water intake information must accompany...trash, sanitary and domestic wastes, produced waters, and chemical product wastes) likely to be generated by...

2013-07-01

295

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

Code of Federal Regulations, 2012 CFR

... false What solid and liquid wastes and discharges information and cooling water intake information must accompany...trash, sanitary and domestic wastes, produced waters, and chemical product wastes) likely to be generated by...

2012-07-01

296

The molecular structure of the interface between water and a hydrophobic substrate is liquid-vapor like  

NASA Astrophysics Data System (ADS)

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.

Willard, Adam P.; Chandler, David

2014-11-01

297

The molecular structure of the interface between water and a hydrophobic substrate is liquid-vapor like.  

PubMed

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. PMID:25399184

Willard, Adam P; Chandler, David

2014-11-14

298

Nuclear quantum effects in liquid water from path-integral simulations using an ab initio force matching approach  

E-print Network

We have applied path integral simulations, in combination with new ab initio based water potentials, to investigate nuclear quantum effects in liquid water. Because direct ab initio path integral simulations are computationally expensive, a flexible water model is parameterized by force-matching to density functional theory-based molecular dynamics simulations. The resulting effective potentials provide an inexpensive replacement for direct ab inito molecular dynamics simulations and allow efficient simulation of nuclear quantum effects. Static and dynamic properties of liquid water at ambient conditions are presented and the role of nuclear quantum effects, exchange-correlation functionals and dispersion corrections are discussed in regards to reproducing the experimental properties of liquid water.

Thomas Spura; Christopher John; Scott Habershon; Thomas D. Kühne

2014-02-06

299

Glass transition dynamics in water and other tetrahedral liquids: 'order disorder' transitions versus 'normal' glass transitions  

NASA Astrophysics Data System (ADS)

We review some aspects of the confusion concerning the glass transition in water, and then show that it must be of a quite different character from that in other molecular liquids, and in fact is the kinetically controlled part of a classical order-disorder transition. (This is the conclusion reached in a review of the low temperature phenomenology of amorphous water currently being published in Science by the present author. Material that would normally appear in the present abbreviated paper will appear in the Science article to which the interested reader is referred.) We do this using a combination of (i) thermodynamic reasoning for 'bulk' water (based on known properties of supercooled water and nearly glassy water), and (ii) direct measurements on nanoscopic (non-crystallizing) water. Both require the heat capacity to be sharply peaked near 220 K and thus to imply the existence of a 'strong-to-fragile' transition during heating. Both require the excess heat capacity to drop to near-vanishing values in the vicinity of 130-150 K. The similarity to order-disorder transitions in crystalline solids is noted, the relation to the second critical point scenario for water is discussed, and the modelling of the anomaly by current theories is considered. Finally we argue that water, with its fragile-to-strong liquid transition below the melting point, links (lies in between) the extremes of classical network liquids (where this transition occurs only above the experimentally accessible range) and fragile molecular liquids, where the fragile-to-strong transition is pushed beneath the glass temperature.

Angell, C. Austen

2007-05-01

300

Determination of pentachlorophenol in water and aquifer sediments by high-performance liquid chromatography  

USGS Publications Warehouse

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.

Goerlitz, D. F.

1981-01-01

301

Measuring the solubilities of ionic liquids in water using ion-selective electrodes  

Microsoft Academic Search

Polyvinyl chloride-plasticized membrane ion-selective electrodes (ISE) based on conventional ion-exchangers have been proposed as a cheap universal tool to measure the solubilities of ionic liquids (ILs) in water. They are applicable for ILs with a wide range of solubilities in water, since the linear range of a potentiometric response spans several orders of magnitude. As an example, we have fabricated

Natalia V. Shvedene; Svetlana V. Borovskaya; Victor V. Sviridov; Erika R. Ismailova; Igor V. Pletnev

2005-01-01

302

Determination of diquat and paraquat in water by liquid chromatography-(electrospray ionization) mass spectrometry  

Microsoft Academic Search

A method for the determination of the herbicides diquat and paraquat in water was developed using liquid chromatography-(electrospray\\u000a ionization) mass spectrometry [LC-(ESI)MS]. The analytes were isolated on an ENVI-8 DSK solid phase extraction (SPE) disk\\u000a and eluted with 5-M trifluoroacetic acid (TFA). The eluate was evaporated to dryness and the analytes were redissolved in\\u000a the mobile phase (7% methanol\\/93% water\\/25-mM

Vince Y. Taguchi; Steve W. D. Jenkins; Patrick W. Crozier; David T. Wang

1998-01-01

303

A molecular dynamics study of Na–dodecylsulfate\\/water liquid crystalline phase  

Microsoft Academic Search

We have performed a Series of long (about 130 ns) molecular dynamics simulations of a sodium dodecylsulfate\\/water liquid crystalline (LC) phase, consisting of 512 sodium dodecylsulfate and 15,000 water molecules, where the initial starting configuration is varied. In addition, the all atom and the united atom model were compared using NAMD and GROMACS codes with CHARMM27 and modified GROMOS87 force fields,

A. H. Poghosyan; G. A. Yeghiazaryan; H. H. Gharabekyan; J. Koetz; A. A. Shahinyan

2007-01-01

304

Determination of 222 Rn in Iranian mineral waters using liquid scintillation alpha-spectrometry  

Microsoft Academic Search

Liquid scintillation counting (LSC) method has been used for the measurement of 222Rn in mineral water samples under a pilot project for the first surveillance in Iran. Low level background LSC counter Quantulus and pulse-shape analysis method have been employed. The concentration of 222Rn found in mineral waters of the studied areas ranges from about 1 to 75 Bq\\/l. The

M. G. Maragheh; S. W. Husain; F. Asgharizadeh; F. Moosavi; M. Anbia

2002-01-01

305

Interaction of a Long Alkyl Chain Protic Ionic Liquid and Water  

E-print Network

A combined experimental/theoretical approach has been used to investigate the role of water in modifying the microscopic interactions characterizing the optical response of 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 ...

Bodo, Enrico; Capitani, Francesco; Gontrani, Lorenzo; Leonelli, Francesca; Postorino, Paolo

2014-01-01

306

Communication: The Effect of Dispersion Corrections on the Melting Temperature of Liquid Water  

SciTech Connect

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.

Yoo, Soohaeng; Xantheas, Sotiris S.

2011-03-28

307

Probing the electronic structure of liquid water with many-body perturbation theory  

NASA Astrophysics Data System (ADS)

We present a first-principles investigation of the electronic structure of liquid water based on many-body perturbation theory (MBPT), within the G0W0 approximation. The liquid quasiparticle band gap and the position of its valence band maximum and conduction band minimum with respect to vacuum were computed and it is shown that the use of MBPT is crucial to obtain results that are in good agreement with experiment. We found that the level of theory chosen to generate molecular dynamics trajectories may substantially affect the electronic structure of the liquid, in particular, the relative position of its band edges and redox potentials. Our results represent an essential step in establishing a predictive framework for computing the relative position of water redox potentials and the band edges of semiconductors and insulators.

Pham, T. Anh; Zhang, Cui; Schwegler, Eric; Galli, Giulia

2014-02-01

308

Excess free energy of liquids from molecular dynamics simulations. Application to water models  

SciTech Connect

Thermodynamic integration and perturbation methods have been applied to calculate the excess free energy, /Delta//Alpha//sub e/, of several models of liquid water. The results for the SPC and TIP models agree well with the experimental excess free energy of liquid water computed from the vapor pressure. The precision of the calculation, in which the nonbonded interaction of all molecules is coupled to a forcing parameter, is demonstrated by the agreement of the computed temperature dependence of /Delta//Alpha//sub e/ with that expected. Some results are presented that show the apparent equivalence of the stepwise perturbation and continuous integration algorithms for this calculation. Finally, it is suggested that the excess free energy of liquids should be among the most important observables used in the parameterization of interatomic potential functions for application in free energy simulations of biological molecules.

Hermans, J.; Pathiaseril, A.; Anderson, A.

1988-08-31

309

Equation of state of ammonia-water liquid - Derivation and planetological applications  

NASA Technical Reports Server (NTRS)

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.

Croft, S. K.; Lunine, J. I.; Kargel, J.

1988-01-01

310

Simulations of the effects of water vapor, cloud liquid water, and ice on AMSU moisture channel brightness temperatures  

NASA Technical Reports Server (NTRS)

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 functions with modal radii greater than 20 micrometers near 157 and 183 GHz, and greater than 30-40 micrometers at 89 GHz. This is due mainly to the relatively small concentrations of droplets much larger than the mode radius. Orographic clouds and tropical cumuli have been observed to contain droplet size distributions with mode radii in the 30-40 micrometers range. Thus, as new instruments bridge the gap between microwave and infrared to frequencies even higher than 183 GHz, radiative transfer modelers are cautioned to explicitly address scattering characteristics of such clouds.

Muller, Bradley M.; Fuelberg, Henry E.; Xiang, Xuwu

1994-01-01

311

Effect of the cation on the interactions between alkyl methyl imidazolium chloride ionic liquids and water.  

PubMed

A systematic study of the interactions between water and alkyl methyl imidazolium chloride ionic liquids at 298.2 K, based on activity coefficients estimated from water activity measurements in the entire solubility range, is presented. The results show that the activity coefficients of water in the studied ILs are controlled by the hydrophilicity of the cation and the cation-anion interaction. To achieve a deeper understanding on the interactions between water and the ILs, COSMO-RS and FTIR spectroscopy were also applied. COSMO-RS was used to predict the activity coefficient of water in the studied ionic liquids along with the excess enthalpies, suggesting the formation of complexes between three molecules of water and one IL molecule. On the basis of quantum-chemical calculations, it is found that cation-anion interaction plays an important role upon the ability of the IL anion to interact with water. The changes in the peak positions/band areas of OH vibrational modes of water as a function of IL concentration were investigated, and the impact of the cation on the hydrogen-bonding network of water is identified and discussed. PMID:25120073

Khan, Imran; Taha, Mohamed; Ribeiro-Claro, Paulo; Pinho, Simão P; Coutinho, João A P

2014-09-01

312

Determination of lead in environmental waters with dispersive liquid-liquid microextraction prior to atomic fluorescence spectrometry.  

PubMed

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

Zhou, Qingxiang; Zhao, Na; Xie, Guohong

2011-05-15

313

Rapid spectrophotometric determination of trace amounts of palladium in water samples after dispersive liquid-liquid microextraction.  

PubMed

A simple, rapid, and efficient dispersive liquid-liquid microextraction method, followed by UV-Vis spectrophotometry was developed for the preconcentration and determination of Pd ions in water samples. Pd ions react with ?-furildioxime (chelating agent) to form a hydrophobic complex. Various parameters were altered to study and optimize their effects on the extraction efficiency, such as pH, ligand concentration, the type and volume of extraction and dispersive solvents, extraction time, and salt concentration. Under optimized conditions, the method exhibited an enrichment factor (C org/C aq) of 25 and recovery more than 98 % within a very short extraction time. The linearity of the method ranged from 10 to 200 ?g?L(-1). The limit of detection was 1.1 ?g?L(-1). The relative standard deviation for the concentration of 100 ?g?L(-1) of Pd was 2.3 % (n?=?10). Finally, the developed method was successfully applied to the extraction and determination of Pd in tap, river, mineral, and sea water samples. PMID:23242461

Rahnama Kozani, Reyhaneh; Mofid-Nakhaei, Jamshid; Jamali, Mohammad Reza

2013-08-01

314

Optical Kerr effect of liquid and supercooled water: the experimental and data analysis perspective  

E-print Network

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 permit a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of sample presenting weak signal, e.g. 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. Hence this data enable a valid comparison between the model fits. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if is intrinsic hydrodynamic approach hide the molecular information.

A. Taschin; P. Bartolini; R. Eramo; R. Righini; R. Torre

2014-06-20

315

Effects of hydrogen bonding on supercooled liquid dynamics and the implications for supercooled water  

E-print Network

The supercooled state of bulk water is largely hidden by unavoidable crystallization, which creates an experimentally inaccessible temperature regime - a 'no man's land'. We address this and circumvent the crystallization problem by systematically studying the supercooled dynamics of hydrogen bonded oligomeric liquids (glycols), where water corresponds to the chain-ends alone. This novel approach permits a 'dilution of water' by altering the hydrogen bond concentration via variations in chain length. We observe a dynamic crossover in the temperature dependence of the structural relaxation time for all glycols, consistent with the common behavior of most supercooled liquids. We find that the crossover becomes more pronounced for increasing hydrogen bond concentrations, which leads to the prediction of a marked dynamic transition for water within 'no man's land' at T~220 K. Interestingly, the predicted transition thus takes place at a temperature where a so called 'strong-fragile' transition has previously been suggested. Our results, however, imply that the dynamic transition of supercooled water is analogous to that commonly observed in supercooled liquids. Moreover, we find support also for the existence of a secondary relaxation of water with behavior analogous to that of the secondary relaxation observed for the glycols.

Johan Mattsson; Rikard Bergman; Per Jacobsson; Lars Börjesson

2008-03-24

316

Determination of Water Soluble Vitamins in Pharmaceutical Preparations Using Liquid Chromatography  

Microsoft Academic Search

A liquid chromatography procedure is described for the simultaneous separation of seven water soluble vitamins in pharmaceutical pteparations. The vitamins are separated on a CR bonded-phase column and eluted with a gradient solvent program. A microprocessor controlled variable wavelength ultraviolet detector is used to automatically change detection wavelength to optimize detection of each vitamin. Pharmaceutical preparations are briefly sonicated in

F. L. Vandemark; G. J. Schmidt

1981-01-01

317

Current use of pressurised liquid extraction and subcritical water extraction in environmental analysis  

Microsoft Academic Search

This review updates our knowledge about pressurised liquid extraction (PLE) and subcritical water extraction (SWE), two sample preparation techniques which are increasingly used for the extraction of moderately and non-volatile organic pollutants from a variety of solid and semi-solid environmental matrices. Parameters influencing the extraction yield and selectivity are discussed. The results deriving from the analysis of several different classes

L Ramos; E. M Kristenson; U. A. Th Brinkman

2002-01-01

318

Isobaric vapor-liquid equilibrium data for the ethanol-water-strontium bromide system  

SciTech Connect

Isobaric experimental data of vapor-liquid equilibrium for the ethanol-water-strontium bromide system at different mole fractions of strontium bromide have been measured at 100.6 kPa. Data were correlated by Jaques and Furter's method. Thermodynamic consistency was checked by Herington's method with satisfactory results.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. (Univ. de Valencia (Spain). Dept. de Ingenieria Quimica)

1994-04-01

319

Switching from water to ionic liquids for the production of methylchloride: Catalysis and reactor issues  

Microsoft Academic Search

The synthesis of methyl chloride from methanol and hydrogen chloride catalysed by zinc chloride was investigated in water and in two room temperature ionic liquids in a CSTR reactor. Both Aliquat336 and BMICl drive to similar rate of reactions as the traditional process albeit at lower temperatures. More importantly, the formation of the side product Me2O is decreased in ionic

Nicolas Dupont; Pierre Grenouillet; Frédéric Bornette; Claude de Bellefon

2009-01-01

320

Doppler Cloud Radar Derived Drop Size Distributions in Liquid Water Stratus Clouds  

Microsoft Academic Search

A cloud particle size retrieval algorithm that uses radar reflectivity factor and Doppler velocity obtained by a 35-GHz Doppler radar and liquid water path estimated from microwave radiometer radiance measurements is developed to infer the size distribution of stratus cloud particles. Assuming a constant, but unknown, number concentration with height, the algorithm retrieves the number concentration and vertical profiles of

Seiji Kato; Gerald G. Mace; Eugene E. Clothiaux; James C. Liljegren; Richard T. Austin

2001-01-01

321

Separation of Phenol from Waste Water by the Liquid Membrane Technique  

Microsoft Academic Search

The removal of phenol and other weakly ionized acids and bases from waste water is described when using the liquid membrane emulsion technique. Mathematical relationships are derived for the theoretical distribution and for the rate of permeation of phenol into the emulsion.

R. P. Cahn; N. N. Li

1974-01-01

322

Liquid water in small solar system bodies, and the possibilities for evolution of life  

Microsoft Academic Search

Much attention has been focused on the few large satellites of Jupiter and Saturn that have evidence of interior layers of liquid water, and the possibility that they may be suitable habitats for life. For life to evolve in these regions, they would have to, at a minimum, produce the necessary chemical constituents to provide energy for building organic matter,

D. W. Sparks; M. M. Tice; L. Farrell; R. S. McGary

2008-01-01

323

Influence of chloride, water, and organic solvents on the physical properties of ionic liquids  

Microsoft Academic Search

We report here the first systematic study of the effect of impurities and additives (e.g., water, chloride, and cosolvents) on the physical properties of room-temperature ionic liquids. Remarkably, it was discovered that the viscosity of mixtures was dependent mainly on the mole fraction of added molecular solvents and only to a lesser extent upon their iden- tity, allowing viscosity changes

Kenneth R. Seddon; Annegret Stark; María-José Torres

2000-01-01

324

MODELING AND TRAJECTORY OPTIMIZATION OF WATER SPRAY COOLING IN A LIQUID PISTON AIR COMPRESSOR  

E-print Network

MODELING AND TRAJECTORY OPTIMIZATION OF WATER SPRAY COOLING IN A LIQUID PISTON AIR COMPRESSOR and expansion has many applications in pneumatic and hydraulic systems, including in the Compressed Air Energy Storage (CAES) system for offshore wind turbine that has recently been proposed in [1,2]. Since the air

Li, Perry Y.

325

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

Microsoft Academic Search

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

Bruce R. Locke; Kai-Yuan Shih

2011-01-01

326

Climatic Implications of the Observed Temperature Dependence of the Liquid Water Path of Low Clouds  

NASA Technical Reports Server (NTRS)

The uncertainty in the global climate sensitivity to an equilibrium doubling of carbon dioxide is often stated to be 1.5-4.5 K, largely due to uncertainties in cloud feedbacks. The lower end of this range is based on the assumption or prediction in some GCMs that cloud liquid water behaves adiabatically, thus implying that cloud optical thickness will increase in a warming climate if the physical thickness of clouds is invariant. Satellite observations of low-level cloud optical thickness and liquid water path have challenged this assumption, however, at low and middle latitudes. We attempt to explain the satellite results using four years of surface remote sensing data from the Atmospheric Radiation Measurements (ARM) Cloud And Radiation Testbed (CART) site in the Southern Great Plains. We find that low cloud liquid water path is insensitive to temperature in winter but strongly decreases with temperature in summer. The latter occurs because surface relative humidity decreases with warming, causing cloud base to rise and clouds to geometrically thin. Meanwhile, inferred liquid water contents hardly vary with temperature, suggesting entrainment depletion. Physically, the temperature dependence appears to represent a transition from higher probabilities of stratified boundary layers at cold temperatures to a higher incidence of convective boundary layers at warm temperatures. The combination of our results and the earlier satellite findings imply that the minimum climate sensitivity should be revised upward from 1.5 K.

DelGenio, Anthony

1999-01-01

327

Performance of the liquid reactivity control system in BWRs (boiling water reactors)  

Microsoft Academic Search

Boiling water reactors rely on the injection of soluble neutron absorbers to control power in case of failure in the control rod (scram) system. Typically this liquid poison'' is injected from eight small holes on a standpipe positioned vertically near the outer edge of the core shroud in the lower plenum. The achievement of control is predicated on good mixing

T. G. Theofanous; E. A. Shabana

1989-01-01

328

Scattering of water from the glycerol liquid-vacuum interface  

NASA Technical Reports Server (NTRS)

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.

Benjamin, I.; Wilson, M. A.; Pohorille, A.; Nathanson, G. M.

1995-01-01

329

Initial evaluation of profiles of temperature, water vapor, and cloud liquid water from a new microwave profiling radiometer.  

SciTech Connect

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 illustrate typical performance for temperature inversion and lapse conditions.

Liljegren, J. C.; Lesht, B. M.; Clothiaux, E. E.; Kato, S.

2000-11-01

330

Photochemical oxidation of water and reduction of polyoxometalate anions at interfaces of water with ionic liquids or diethylether  

PubMed Central

Photoreduction of [P2W18O62]6-, [S2Mo18O62]4-, and [S2W18O62]4- polyoxometalate anions (POMs) and oxidation of water occurs when water–ionic liquid and water–diethylether interfaces are irradiated with white light (275–750 nm) or sunlight. The ionic liquids (ILs) employed were aprotic ([Bmim]X; Bmim = (1-butyl-3-methylimidazolium,X = BF4,PF6) and protic (DEAS = diethanolamine hydrogen sulphate; DEAP = diethanolamine hydrogen phosphate). Photochemical formation of reduced POMs at both thermodynamically stable and unstable water–IL interfaces led to their initial diffusion into the aqueous phase and subsequent extraction into the IL phase. The mass transport was monitored visually by color change and by steady-state voltammetry at microelectrodes placed near the interface and in the bulk solution phases. However, no diffusion into the organic phase was observed when [P2W18O62]6- was photo-reduced at the water–diethylether interface. In all cases, water acted as the electron donor to give the overall process: 4POM + 2H2O + h? ? 4POM- + 4H+ + O2. However, more highly reduced POM species are likely to be generated as intermediates. The rate of diffusion of photo-generated POM- was dependent on the initial concentration of oxidized POM and the viscosity of the IL (or mixed phase system produced in cases in which the interface is thermodynamically unstable). In the water-DEAS system, the evolution of dioxygen was monitored in situ in the aqueous phase by using a Clark-type oxygen sensor. Differences in the structures of bulk and interfacial water are implicated in the activation of water. An analogous series of reactions occurred upon irradiation of solid POM salts in the presence of water vapor. PMID:22753501

Bernardini, Gianluca; Wedd, Anthony G.; Zhao, Chuan; Bond, Alan M.

2012-01-01

331

Interaction of a long alkyl chain protic ionic liquid and water.  

PubMed

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. PMID:24880297

Bodo, Enrico; Mangialardo, Sara; Capitani, Francesco; Gontrani, Lorenzo; Leonelli, Francesca; Postorino, Paolo

2014-05-28

332

Pore-network modeling of liquid water transport in gas diffusion layer of a polymer electrolyte fuel cell  

Microsoft Academic Search

A pore-network model is developed to study the liquid water movement and flooding in a gas diffusion layer (GDL), with the GDL morphology taken into account. The dynamics of liquid water transport at the pore-scale and evolution of saturation profile in a GDL under realistic fuel cell operating conditions is examined for the first time. It is found that capillary

Puneet K. Sinha; Chao-Yang Wang

2007-01-01

333

Cloud Liquid Water Path for the Rain/No-rain Classification Method over Ocean in the GSMaP Algorithm  

NASA Astrophysics Data System (ADS)

The rain/no-rain threshold value of cloud liquid water path is important for rain/no-rain classification in microwave precipitation retrieval algorithms. In our previous study, we proposed a parameterization of rain/no-rain threshold value of cloud liquid water path as a function of storm height for the Global Satellite Mapping of Precipitation (GSMaP) algorithm. In this study, we determine rain/no-rain threshold value of cloud liquid water path using the CloudSat precipitation product. The threshold values of cloud liquid water path from the CloudSat precipitation product are lower than 0.5 kg m-2 for GSMaP over all regions. The threshold value of cloud liquid water path is found at its peak in the tropics and decreases poleward. The threshold value of cloud liquid water content computed from threshold value of cloud liquid water path divided by the zonal mean storm height is employed on the parameterization of threshold values of cloud liquid water path. The result shows that GSMaP with new parameterization can detect the shallow rain observed by CloudSat and improves the rain-rate distribution over rain rate less than 0.1 mm h-1.

Kida, Satoshi; Shige, Shoichi; Manabe, Takeshi; L'Ecuyer, Tristan; Liu, Gousheng

334

A new retrieval for cloud liquid water path using a ground-based microwave radiometer and measurements of cloud temperature  

Microsoft Academic Search

A new method to retrieve cloud liquid water path using 23.8 and 31.4 GHz microwave radiometer brightness temperature measurements is developed. This method does not depend on climatological estimates of either the mean radiating temperature of the atmosphere Tmr or the mean cloud liquid water temperature Tcloud. Rather, Tmr is estimated from surface temperature and relative humidity measurements, while Tcloud

James C. Liljegren; Eugene E. Clothiaux; Gerald G. Mace; Seiji Kato; Xiquan Dong

2001-01-01

335

Importance of Accurate Liquid Water Path for Estimation of Solar Radiation in Warm Boundary Layer Clouds: An Observational Study  

Microsoft Academic Search

A 1-yr observational study of overcast boundary layer stratus at the U.S. Department of Energy Atmospheric Radiation Measurement Program Southern Great Plains site illustrates that surface radiation has a higher sensitivity to cloud liquid water path variations when compared to cloud drop effective radius variations. The mean, median, and standard deviation of observed cloud liquid water path and cloud drop

Manajit Sengupta; Eugene E. Clothiaux; Thomas P. Ackerman; Seiji Kato; Qilong Min

2003-01-01

336

Aromatic-aromatic interactions: Free energy profiles for the benzene dimer in water, chloroform, and liquid benzene  

Microsoft Academic Search

An all-atom model for benzene is reported and tested largely in Monte Carlo simulations of pure liquid benzene, benzene in dilute aqueous solution, and the benzene dimer in water and chloroform. Free energy profiles were obtained for the association of the benzene dimer in liquid benzene, water, and chloroform that characterize the energetics for this prototypical interaction between arenes in

William L. Jorgensen; Daniel L. Severance

1990-01-01

337

EVALUATION OF THE DIURNAL CYCLE OF MODEL PREDICTED CLOUD LIQUID WATER PATH WITH MSG-SEVIRI OBSERVATIONS  

E-print Network

EVALUATION OF THE DIURNAL CYCLE OF MODEL PREDICTED CLOUD LIQUID WATER PATH WITH MSG Liquid Water path (LWP) in climate models receives relatively little attention. This is partly due on diurnal cycles of LWP over land and ocean surfaces. This paper evaluates diurnal cycles of LWP

Haak, Hein

338

On the scientific utility of surface-based liquid water path measurements in marine stratus Paquita Zuidema (1)  

E-print Network

On the scientific utility of surface-based liquid water path measurements in marine stratus Paquita,are subject to uncertainties introduced by an angle-dependent polarized reflecting surface (i.e.ocean waves analysis,is to a large degree influenced by how well the cloud liquid water paths (LWPs) can be known

Zuidema, Paquita

339

TOWARDS A STATISTICAL CLIMATOLOGY OF THE RELATIONSHIP OF BETWEEN UPDRAFT VELOCITY, LIQUID WATER PATH, AND CLOUD DROPLET  

E-print Network

TOWARDS A STATISTICAL CLIMATOLOGY OF THE RELATIONSHIP OF BETWEEN UPDRAFT VELOCITY, LIQUID WATER afford an opportunity to establish the foundation for a climatology of thin layer clouds at all ARM sites clouds. Clouds are subsequently classified according to liquid water path, and a climatology

340

Measuring transport of liquid water through organic coatings adhered to a substrate  

SciTech Connect

A method based on FTIR-multiple internal reflection (FTIR-MIR) spectroscopy was developed for measuring the diffusion coefficient of liquid water through a coating adhered to a substrate. The method requires an application of the coating of any thickeness, l on an internal reflection element and an attachment of a water chamber to the coated specimen. Water is introduced to the chamber and FTIR-MIR spectra are collected automatically at specified time intervals. An FTIR-MIR spectral intensity-time curve for water is established, which provides t{sub in}, the time required for water to diffuse through the coating and reach the coating/substrate interface. D is calculated from the expression: D=l{sup 2}/6t{sub in}. The sensitivity of FTIR-MIR spectroscopy and the strong FTIR absorption of water molecules make this an ideal method for measuring D of liquid water through a coating adhered to a substrate. This quantity may be used for interpreting corrosion, blistering, and water disbondment of organic-coated substrates.

Nguhen, T.; Byrd, E.; Bentz, D. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

1993-12-31

341

Dispersive liquid-liquid microextraction combined with high-performance liquid chromatography for the enrichment and sensitive determination of Sudan Red pollutants in water samples.  

PubMed

Sudan Red pollutants have gained more attention in recent years. The present study described a simple and sensitive determination method for Sudan Red pollutants with dispersive liquid-liquid microextraction coupled to high-performance liquid chromatography. Chlorobenzene and ethanol were used as the extraction solvent and disperser solvent, respectively. The possible parameters such as the kind of solvents, ionic strength, and sample pH that could affect the enrichment have been optimized. Under the optimal conditions, the pollutants have been well enriched and the linear ranges of Sudan Red I and II were in the range of 0.3-40 ?g/L, and the linear ranges of Sudan Red III and IV were in the range of 1.2-160 ?g/L. The detection limits were in the range of 0.18-0.46 ?g/L, and the precisions were in the range of 3.7-5.9%. All these demonstrated that the proposed method could be a good alternative for the routine analysis of Sudan Red pollutants in water samples. PMID:25267482

Zhou, Qingxiang; Zhao, Kuifu; Xing, An

2014-11-01

342

Isobaric vapor-liquid equilibrium for ethanol + water + copper(II) chloride  

SciTech Connect

The extractive distillation in which an electrolyte is employed as the extractive agent is an important alternative to the conventional methods for separating mixtures involving azeotropes. Isobaric vapor-liquid equilibrium for ethanol (1) + water(2) + copper(II) chloride (3) at different mole fractions of copper(II) chloride has been measured at 100.0 kPa. The results in the range where the mole fraction of salt in the liquid phase was less than 0.146 times the mole fraction of water were correlated by assuming that the salt was in ionic form and it was associated only with the water. Thermodynamic consistency was checked according to Herington`s method with satisfactory results.

Vercher, E.; Pena, M.P.; Martinez-Andreu, A. [Univ. de Valencia (Spain). Dept. de Ingenieria Quimica

1995-05-01

343

MWRRET Value-Added Product: The Retrieval of Liquid Water Path and Precipitable Water Vapor from Microwave Radiometer (MWR) Datasets  

SciTech Connect

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).

KL Gaustad; DD Turner

2007-09-30

344

Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.  

PubMed

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

Padró, Juan M; Pellegrino Vidal, Rocío B; Reta, Mario

2014-12-01

345

Water-cooled liquid and solid breeder blanket concepts  

SciTech Connect

Four concepts have been evaluated: (1) lithium oxide breeder (Li/sub 2/O) with and without beryllium neutron multiplier (Li/sub 2/O/H/sub 2/O, Li/sub 2/O/H/sub 2/O/Be); (2) ternary oxide ceramic breeder (..gamma..-LiA1O/sub 2/) with beryllium neutron multiplier (LiA1O/sub 2//H/sub 2/O/Be); (3) ..gamma..-LiA1O/sub 2/ with lead neutron multiplier (LiA1O/sub 2//H/sub 2/O/Pb); and (4) 17Li-83Pb breeder without a separate neutron multiplier (LiPb/H/sub 2/O). Candidate structural materials are austenitic stainless steel (PCA), ferritic steel (HT-9), and vanadium alloy (V-15Cr-5Ti). The pressurized water coolant is assumed to be at 280/sup 0/C inlet, 320/sup 0/C outlet, and 15.2 MPa design pressure.

Morgan, G.D.; Bowers, D.; Hellwig, T.; Ruester, D.; Sze, D.K.; Johnson, C.; Jung, J.; Liu, Y.Y.; Misra, B.; Gordon, J.

1984-01-01

346

Sol–gel synthesis of vanadium pentoxide nanoparticles in air- and water-stable ionic liquids  

Microsoft Academic Search

Vanadium pentoxide (V2O5) nanoparticles were synthesized at moderate reaction temperatures by hydrolysis of VO[OCH(CH3)2]3 in two different air- and water-stable ionic liquids with the same anion: 1-butyl-1-methyl pyrrolidinium bis(trifluoromethylsulfonyl)amide\\u000a ([Py1,4]Tf2N) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIM]Tf2N) via the sol–gel method using acetone and isopropanol either as refluxing solvents or as co-solvents. The cation type of\\u000a the ionic liquid affects the crystallinity, morphology,

Mohammad Al Zoubi; Hala K. Farag; Frank Endres

2009-01-01

347

Water-in-Ionic Liquid Microemulsion Formation in Solvent Mixture of Aprotic and Protic Imidazolium-Based Ionic Liquids.  

PubMed

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

Kusano, Takumi; Fujii, Kenta; Hashimoto, Kei; Shibayama, Mitsuhiro

2014-10-14

348

VAPOR + LIQUID EQUILIBRIUM OF WATER, CARBON DIOXIDE, AND THE BINARY SYSTEM WATER + CARBON DIOXIDE FROM  

E-print Network

(for water: the SPC-, SPC/E-, and TIP4P-potential models; for carbon dioxide: the EPM2 potential model. The interactions between carbon dioxide and water were estimated from the pair potentials of the pure components of intermolecular pair potentials for various substances is documented. Especially water has been the subject

349

Estrogenic compounds determination in water samples by dispersive liquid-liquid microextraction and micellar electrokinetic chromatography coupled to mass spectrometry.  

PubMed

In this work, a group of 12 estrogenic compounds, i.e., four natural sexual hormones (estrone, 17?-estradiol, 17?-estradiol and estriol), an exoestrogen (17?-ethynylestradiol), a synthetic stilbene (dienestrol), a mycotoxin (zearalenone) and some of their major metabolites (2-methoxyestradiol, ?-zearalanol, ?-zearalanol, ?-zearalenol and ?-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 ?L of chloroform and 500 ?L 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 ?g/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

D'Orazio, Giovanni; Asensio-Ramos, María; Hernández-Borges, Javier; Fanali, Salvatore; Rodríguez-Delgado, Miguel Ángel

2014-05-30

350

Investigation of Uranium Polymorphs  

SciTech Connect

The UO3-water system is complex and has not been fully characterized, even though these species are common throughout the nuclear fuel cycle. As an example, most production schemes for UO3 result in a mixture of up to six or more different polymorphic phases, and small differences in these conditions will affect phase genesis that ultimately result in measureable changes to the end product. As a result, this feature of the UO3-water system may be useful as a means for determining process history. This research effort attempts to better characterize the UO3-water system with a variety of optical techniques for the purpose of developing some predictive capability for estimating process history in polymorphic phases of unknown origin. Three commercially relevant preparation methods for the production of UO3 were explored. Previously unreported low temperature routes to ?- and ?-UO3 were discovered. Raman and fluorescence spectroscopic libraries were established for pure and mixed polymorphic forms of UO3 in addition to the common hydrolysis products of UO3. An advantage of the sensitivity of optical fluorescence microscopy over XRD has been demonstrated. Preliminary aging studies of the ? and ? forms of UO3 have been conducted. In addition, development of a 3-D phase field model used to predict phase genesis of the system was initiated. Thermodynamic and structural constants that will feed the model have been gathered from the literature for most of the UO3 polymorphic phases.

Sweet, Lucas E.; Henager, Charles H.; Hu, Shenyang Y.; Johnson, Timothy J.; Meier, David E.; Peper, Shane M.; Schwantes, Jon M.

2011-08-01

351

Determination of selected azaarenes in water by bonded-phase extraction and liquid chromatography  

USGS Publications Warehouse

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.

Steinheimer, T. R.; Ondrus, M. G.

1986-01-01

352

Imbibition in mesoporous silica: rheological concepts and experiments on water and a liquid crystal.  

PubMed

We present, along with some fundamental concepts regarding imbibition of liquids in porous hosts, an experimental, gravimetric study on the capillarity-driven invasion dynamics of water and of the rod-like liquid crystal octyloxycyanobiphenyl (8OCB) in networks of pores a few nanometers across in monolithic silica glass (Vycor). We observe, in agreement with theoretical predictions, square root of time invasion dynamics and a sticky velocity boundary condition for both liquids investigated. Temperature-dependent spontaneous imbibition experiments on 8OCB reveal the existence of a paranematic phase due to the molecular alignment induced by the pore walls even at temperatures well beyond the clearing point. The ever present velocity gradient in the pores is likely to further enhance this ordering phenomenon and prevent any layering in molecular stacks, eventually resulting in a suppression of the smectic phase in favor of the nematic phase. PMID:21508488

Gruener, Simon; Huber, Patrick

2011-05-11

353

Imbibition in mesoporous silica: rheological concepts and experiments on water and a liquid crystal  

NASA Astrophysics Data System (ADS)

We present, along with some fundamental concepts regarding imbibition of liquids in porous hosts, an experimental, gravimetric study on the capillarity-driven invasion dynamics of water and of the rod-like liquid crystal octyloxycyanobiphenyl (8OCB) in networks of pores a few nanometers across in monolithic silica glass (Vycor). We observe, in agreement with theoretical predictions, square root of time invasion dynamics and a sticky velocity boundary condition for both liquids investigated. Temperature-dependent spontaneous imbibition experiments on 8OCB reveal the existence of a paranematic phase due to the molecular alignment induced by the pore walls even at temperatures well beyond the clearing point. The ever present velocity gradient in the pores is likely to further enhance this ordering phenomenon and prevent any layering in molecular stacks, eventually resulting in a suppression of the smectic phase in favor of the nematic phase.

Gruener, Simon; Huber, Patrick

2011-05-01

354

The molecular structure of the interface between water and a hydrophobic substrate is liquid-vapor like  

E-print Network

With molecular simulation for water and a tunable hydrophobic substrate, we apply the instantaneous interface construction [A. P. Willard and D. Chandler, J. Phys. Chem. B, 114, 1954 (2010)] to examine the similarity between a water-vapor interface and a water-hydrophobic surface interface. The intrinsic interface refers to molecular structure in terms of distances from the instantaneous 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. 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.

Adam P. Willard; David Chandler

2014-07-16

355

Remote measurements of ozone, water vapor and liquid water content, and vertical profiles of temperature in the lower troposphere  

NASA Technical Reports Server (NTRS)

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.

Grant, W. B.; Gary, B. L.; Shumate, M. S.

1983-01-01

356

Two-channel microwave radiometer for observations of total column precipitable water vapor and cloud liquid water path  

SciTech Connect

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.

Liljegren, J.C.

1994-01-01

357

In situ separation of root hydraulic redistribution of soil water from liquid and vapor transport  

SciTech Connect

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.

Warren, Jeffrey [ORNL; Brooks, J Renee [U.S. Environmental Protection Agency, Corvallis, OR; Dragila, Maria [Oregon State University, Corvallis; Meinzer, Rick [USDA Forest Service

2011-01-01

358

Liquid-Water Uptake and Removal in PEM Fuel-Cell Components  

SciTech Connect

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.

Das, Prodip K.; Gunterman, Haluna P.; Kwong, Anthony; Weber, Adam Z.

2011-09-23

359

Low-Dimensional Water on Ru(0001)Model System for X-ray Absorption Spectroscopy Studies of Liquid Water  

SciTech Connect

We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

Nordlund, D

2012-02-14

360

Determination of thiophanate-methyl and its metabolites at trace level in spiked natural water using the supported liquid membrane extraction and the microporous membrane liquid-liquid extraction techniques combined on-line with high-performance liquid chromatography.  

PubMed

On-line supported liquid membrane (SLM) extraction and microporous membrane liquid-liquid extraction (MMLLE) techniques for sample preparation of natural water samples have been developed for the determination of thiophanate-methyl (TM), carbendazim (MBC) and 2-aminobenzimidazole (2-AB) using reversed-phase HPLC. The combination of SLM extraction and MMLLE offers extraction conditions that makes it possible to determine a wide variety of compounds, i.e., permanently charged, ionisable and non-polar at sub ppb level. The detection limits obtained after extraction are about 0.1 microg/l for MBC and 2-AB using SLM, and 0.5 x Lg/l for TM using MMLLE and the precision is better than 5% for both systems. Typical enrichment rates are 0.6 and 2.7 times/min using SLM and MMLLE, respectively. PMID:11043593

Sandahl, M; Mathiasson, L; Jönsson, J A

2000-09-29

361

Analysis of water-soluble vitamins in total parenteral nutrition solution by high pressure liquid chromatography  

Microsoft Academic Search

A stability-indicating high pressure liquid chromatographic method was developed to determine the stability of water-soluble vitamins in total parenteral nutrition mixtures. Folic acid and thiamine were determined by direct injection and precolumn enrichment, followed by UV detection. Nicotinamide and pyridoxine were determined simultaneously without sample pretreatment by UV detection of nicotinamide and fluorescence detection of pyridoxine. Riboflavin 5?-phosphate was also

A. van der Horst; H. J. M. Martens; P. N. F. C. de Goede

1989-01-01

362

Restricted rotation dynamics and far-infrared spectra of liquid water governed by elastic interactions  

Microsoft Academic Search

A semi-phenomenological model describing wideband dielectric and far-infrared spectra of liquid water was proposed recently by the same authors [J. Mol. Struct. 606 (2002) 9], where a small dipole-moment component changing harmonically with time determines a weak absorption band (termed here the R-band) centred at the wavenumber ??200cm?1. In the present work, a rough molecular theory of the R-band based

V. I Gaiduk; D. S. F Crothers; Ch. M Briskina; B. M Tseitlin

2004-01-01

363

Inelastic-collision cross sections of liquid water for interactions of energetic protons  

Microsoft Academic Search

Cross-section data for inelastic interactions of energetic protons with liquid water, for use, e.g. as input in track structure analysis, are derived for an energy range from 0.1 keV to 10 GeV. At proton kinetic energies above about 500 keV, the first Born approximation and the dielectric-response function determined earlier are used. At proton energies above several hundred MeV in

M. Dingfelder; M. Inokuti; H. G. Paretzke

2000-01-01

364

Determination of phenols in environmental waters using liquid chromatography with electrochemical detection  

Microsoft Academic Search

The development of a liquid chromatographic method for the determination of priority pollutant phenols at low ?g\\/l levels in environmental waters is discussed. The phenols were separated using a Nova-Pak Phenyl column with concave gradient elution from 20 mM ammonium acetate (19% acetonitrile) to 20 mM ammonium acetate (54% acetonitrile) over 12 min, and subsequently detected using an electrochemical detector

B. Paterson; C. E. Cowie; P. E. Jackson

1996-01-01

365

Nearest-neighbor distributions of free radicals produced within charged-particle tracks in liquid water  

E-print Network

Charged-Particle Tracks in Liquid Water. (1990) Miles Clay Smith, B. S. , The University of Oklahoma Chair of Advisory Committee: Dr. Wesley Bolch In this work, the chemical structure of electron, proton, and alpha particle tracks are characterized... the initial energy deposition (3). Therefoxe, it is important to know the chemical structure of charged-particle tracks. In this thesis, a method is presented which describes charged-particle tracks by the distribution of distances between their chemical...

Smith, Miles Clay

2012-06-07

366

Antioxidant compounds from Eucalyptus grandis biomass by subcritical liquid water extraction  

Microsoft Academic Search

The effectiveness of subcritical liquid water processing for extraction of antioxidants from the leaves of Eucalyptus grandis biomass was evaluated by determining the capability of the processed samples to scavenge peroxynitrite radicals in vitro,\\u000a as compared with the extracts obtained by conventional extraction. Pyrogallol (1), 5-hydroxymethyl-2-furaldehyde (2), and 4,4,6,6-tetramethyl-3,5-dioxo-cyclohex-1-enecarboxylic acid (3) were identified as the major products obtained from the

Aditya Kulkarni; Shunsuke Suzuki; Hideo Etoh

2008-01-01

367

Formation of reactive species in gliding arc discharges with liquid water  

Microsoft Academic Search

The effects of gas composition on gliding arc (glidarc) electrical discharge reactors with pure water have been studied. The glidarc reactors utilized AC electrical discharges with two different electrode configurations. In one case a set of two stainless steel electrodes connected to a single power supply was placed in the gas phase over the liquid surface (power=250–300W, maximum voltage=12kV). The

Radu Burlica; Michael J. Kirkpatrick; Bruce R. Locke

2006-01-01

368

Femtosecond Dynamics of Hydrogen Bonds in Liquid Water: A Real Time Study  

Microsoft Academic Search

A pump-probe experiment is described to study femtosecond dynamics of hydrogen bonds in liquid water. The key element of the experimental setup is a laser source emitting 150 fs pulses in the 2.5-4.4 mum spectral region, at a 10 muJ power level. The OH-stretching band is recorded for different excitation frequencies and different pump-probe delay times. Time-dependent solvatochromic shifts are

G. M. Gale; G. Gallot; F. Hache; N. Lascoux; S. Bratos; J.-Cl. Leicknam

1999-01-01

369

Analysis and Calibration of CRF Raman Lidar Cloud Liquid Water Measurements  

SciTech Connect

The Atmospheric Radiation Measurement (ARM) Raman lidar (RL), located at the Southern Great Plains (SGP) Climate Research Facility (CRF), is a unique state-of-the-art active remote sensor that is able to measure profiles of water vapor, aerosol, and cloud properties at high temporal and vertical resolution throughout the diurnal cycle. In October 2005, the capability of the RL was extended by the addition of a new detection channel that is sensitive to the Raman scattering of liquid water. This new channel permits the system, in theory, to measure profiles of liquid water content (LWC) by the RL. To our knowledge, the ARM RL is the only operation lidar with this capability. The liquid water Raman backscattering cross-section is a relatively weak and spectrally broad feature, relative to the water vapor Raman backscatter signal. The wide bandpass required to achieve reasonable signal-to-noise in the liquid water channel essentially eliminates the ability to measure LWC profiles during the daytime in the presence of large solar background, and thus all LWC observations are nighttime only. Additionally, the wide bandpass increases the probability that other undesirable signals, such as fluorescence from aerosols, may contaminate the observation. The liquid water Raman cross-section has a small amount of overlap with the water vapor Raman cross-section, and thus there will be a small amount of ‘cross-talk’ between the two signals, with water vapor contributing a small amount of signal to the LWC observation. And finally, there is significant uncertainty in the actual strength of the liquid water Raman cross-section in the literature. The calibrated LWC profiles, together with the coincident cloud backscatter observations also made by the RL, can be used to derive profiles of cloud droplet effective radius. By combining these profiles of effective radius in the lower portion of the cloud with the aerosol extinction measurements made below the cloud by the RL, the first aerosol indirect effect can be investigated using a single instrument, thereby reducing the uncertainty associated with aligning the different sampling periods and fields of view of multiple instruments. We have applied a “first principles” calibration to the LWC profiles. This approach requires that the relative differences in optical efficiency between the water vapor and liquid water channels be known; this relative difference is easily computed using the efficiency values of the beam splitters and interference filters in the lidar that were provided by the vendors of these components. The first principles approach then transfers the calibration from the water vapor mixing ratio to the LWC using the difference in the optical efficiency and an interpolated value of the liquid water Raman cross section from the literature, and the better established water vapor Raman cross section. After accounting for all known error sources, the vertical integral of LWC was compared against a similar value retrieved from a co-located ground-based infrared radiometer. The RL and infrared radiometer have significantly different fields of view; thus to compare the two sensors the data were averaged to 5 min intervals where only cloudy samples were included in the average of each. While there is fair scatter in the data (r=0.47), there is also a clear indication of a positive correlation between the infrared and the RL values. The value of the slope of the regression is 0.49, which indicates a tendency of the RL measurements to underestimate the total liquid amount with respect to the infrared retrieval. Research continues to investigate the source of the bias, but the most likely candidate is the large uncertainty in the liquid water Raman cross-section as there have been no direct measurements made of this parameter at the lidar’s laser wavelength of 355 nm. The calibrated LWC profile was then used together with the cloud backscatter coefficient profile from the RL to derive profiles of cloud droplet effective radius and cloud droplet number density. These profiles o

Turner, D.D.

2007-10-31

370

Effect of the supporting electrolytes on voltammetry at liquid\\/liquid microinterfaces between water and nitrobenzene, 1,2-dichloroethane or 1,6-dichlorohexane  

Microsoft Academic Search

The transfers of the ions of tetraalkylammonium picrates (-methyl, -ethyl, -propyl, -butyl), from water (W) to nitrobenzene (NB), 1,2-dichloroethane (DCE) or 1,6-dichlorohexane (DCH), have been studied by voltammetry at liquid\\/liquid microinterfaces. Electrochemistry is possible in the absence of supporting electrolytes in both phases, even in the less dissociating solvents, DCE and DCH, when the concentration of the picrate is lower

Mickaël Rimboud; Kevin Charreteur; Vladimir Sladkov; Catherine Elleouet; François Quentel; Maurice L’Her

2009-01-01

371

Part-per-trillion determination of chlorobenzenes in water using dispersive liquid–liquid microextraction combined gas chromatography–electron capture detection  

Microsoft Academic Search

In this study, a simple, rapid and efficient method, dispersive liquid–liquid microextraction (DLLME) combined gas chromatography–electron capture detection (GC–ECD), for the determination of chlorobenzenes (CBs) in water samples, has been described. This method involves the use of an appropriate mixture of extraction solvent (9.5?l chlorobenzene) and disperser solvent (0.50ml acetone) for the formation of cloudy solution in 5.00ml aqueous sample

Reyhaneh Rahnama Kozani; Yaghoub Assadi; Farzaneh Shemirani; Mohammad-Reza Milani Hosseini; Mohammad Reza Jamali

2007-01-01

372

Air-liquid interface of ionic liquid-water binary system studied by surface tension measurement and sum-frequency generation spectroscopy  

Microsoft Academic Search

Surface of room-temperature ionic liquid (RIL)+water mixture is investigated using surface tension measurement and surface sum- frequency generation (SFG) vibrational spectroscopy. Results indicate the liquid surface is mostly covered by the cations at a very low bulk concentration (less than 0.02 bulk mole fraction). Increase of surface tension from 0.016 up to ˜0.05 mole fraction suggested that the anions start

Jaeho Sung; Takashi Iwahashi

2005-01-01

373

Ultrafast dynamics of liquid water: Frequency fluctuations of the OH stretch and the HOH bend  

SciTech Connect

Frequency fluctuations of the OH stretch and the HOH bend in liquid water are reported from the third-order response function evaluated using the TTM3-F potential for water. The simulated two-dimensional infrared (IR) spectra of the OH stretch are similar to previously reported theoretical results. The present study suggests that the frequency fluctuation of the HOH bend is faster than that of the OH stretch. The ultrafast loss of the frequency correlation of the HOH bend is due to the strong couplings with the OH stretch as well as the intermolecular hydrogen bond bend.

Imoto, Sho; Xantheas, Sotiris S.; Saito, Shinji

2013-07-28

374

Electronic structure effects in liquid water studied by photoelectron spectroscopy and density functional theory  

SciTech Connect

We present valence photoelectron emission spectra of liquid water in comparison with gas-phase water, ice close to the melting point, low temperature amorphous and crystalline ice. All aggregation states have major electronic structure changes relative to the free molecule, with rehybridization and development of bonding and anti-bonding states accompanying the hydrogen bond formation. Sensitivity to the local structural order, most prominent in the shape and splitting of the occupied 3a{sub 1} orbital, is understood from the electronic structure averaging over various geometrical structures, and reflects the local nature of the orbital interaction.

Nordlund, Dennis; Odelius, Michael; Bluhm, Hendrik; Ogasawara, Hirohito; Pettersson, Lars G.M.; Nilsson, Anders

2008-04-29

375

On the Electronic Nature of the Surface Potential at the Vapor-Liquid Interface of Water  

SciTech Connect

The surface potential at the vapor-liquid interface of water is relevant to many areas of chemical physics. Measurement of the surface potential has been experimentally attempted many times, yet there has been little agreement as to its magnitude and sign (-1.1 to +0.5 mV). We present the first computation of the surface potential of water using ab initio molecular dynamics. We find that the surface potential {chi} = -18 mV with a maximum interfacial electric field = 8.9 x 10{sup 7} V/m. A comparison is made between our quantum mechanical results and those from previous molecular simulations. We find that explicit treatment of the electronic density makes a dramatic contribution to the electric properties of the vapor-liquid interface of water. The E-field can alter interfacial reactivity and transport while the surface potential can be used to determine the 'chemical' contribution to the real and electrochemical potentials for ionic transport through the vapor-liquid interface.

Kathmann, S M; Kuo, I; Mundy, C J

2008-02-05

376

The Cotton-Mouton effect of liquid water. Part II: The semi-continuum model  

NASA Astrophysics Data System (ADS)

We present gauge-origin independent calculations of the Cotton-Mouton effect of liquid water. The liquid is represented by a semi-continuum model such that the central molecule is surrounded by its first solvation shell, which explicitly accounts for the strong interaction between the water molecule of interest and its closest neighbors. The long-range interactions with the solvent are modeled by a dielectric continuum surrounding the water molecule and the first solvation shell. We employ large basis sets, using London atomic orbitals in order to obtain gauge-origin independent results close to the Hartree-Fock limit. It is demonstrated that the direct interaction between neighboring molecules leads to a large effect on the calculated Cotton-Mouton constant, which undergoes a sign change from the gas to liquid phase, as observed previously for the linear electro-optical effect [K. V. Mikkelsen et al., J. Chem. Phys 102, 9362 (1995)]. Our best estimate for the molar Cotton-Mouton constant, -38.1?10-20 G-2 cm3 mol-1 (corrected for local field effects), is in reasonable agreement with the experimental value of -118(15)?10-20 G-2 cm3 mol-1. We expect that the remaining discrepancy is mainly due to an inadequate treatment of electron correlation.

Ruud, Kenneth; A?Gren, Hans; Dahle, Pa?L.; Helgaker, Trygve; Rizzo, Antonio; Coriani, Sonia; Koch, Henrik; Sylvester-Hvid, Kristian O.; Mikkelsen, Kurt V.

1998-01-01

377

Calculated depth-dose distributions for H + and He + beams in liquid water  

NASA Astrophysics Data System (ADS)

We have calculated the dose distribution delivered by proton and helium beams in liquid water as a function of the target-depth, for incident energies in the range 0.5-10 MeV/u. The motion of the projectiles through the stopping medium is simulated by a code that combines Monte Carlo and a finite differences algorithm to consider the electronic stopping power, evaluated in the dielectric framework, and the multiple nuclear scattering with the target nuclei. Changes in projectile charge-state are taken into account dynamically as it moves through the target. We use the MELF-GOS model to describe the energy loss function of liquid water, obtaining a value of 79.4 eV for its mean excitation energy. Our calculated stopping powers and depth-dose distributions are compared with those obtained using other methods to describe the energy loss function of liquid water, such as the extended Drude and the Penn models, as well as with the prediction of the SRIM code and the tables of ICRU.

Garcia-Molina, Rafael; Abril, Isabel; Denton, Cristian D.; Heredia-Avalos, Santiago; Kyriakou, Ioanna; Emfietzoglou, Dimitris

2009-08-01

378

Isobaric-isothermal Monte Carlo simulations from first principles: Application to liquid water at ambient conditions  

SciTech Connect

A series of first principles Monte Carlo simulations in the isobaric-isothermal ensemble were carried out for liquid water at ambient conditions (T = 298 K and p = 1 atm). The Becke-Lee-Yang-Parr (BLYP) exchange and correlation energy functionals and norm-conserving Goedecker-Teter-Hutter (GTH) pseudopotentials were employed with the CP2K simulation package to examine systems consisting of 64 water molecules. The fluctuations in the system volume encountered in simulations in the isobaric-isothermal ensemble requires a reconsideration of the suitability of the typical charge density cutoff and the regular grid generation method previously used for the computation of the electrostatic energy in first principles simulations in the microcanonical or canonical ensembles. In particular, it is noted that a much higher cutoff is needed and that the most computationally efficient method of creating grids can result in poor simulations. Analysis of the simulation trajectories using a very large charge density cutoff at 1200 Ry and four different grid generation methods point to a substantially underestimated liquid density of about 0.85 g/cm{sup 3} resulting in a somewhat understructured liquid (with a value of about 2.7 for the height of the first peak in the oxygen/oxygen radial distribution function) for BLYP-GTH water at ambient conditions.

McGrath, M; Siepmann, J I; Kuo, I W; Mundy, C J; VandeVondele, J; Hutter, J; Mohamed, F; Krack, M

2004-12-02

379

Emissions Prediction and Measurement for Liquid-Fueled TVC Combustor with and without Water Injection  

NASA Technical Reports Server (NTRS)

An investigation is performed to evaluate the performance of a computational fluid dynamics (CFD) tool for the prediction of the reacting flow in a liquid-fueled combustor that uses water injection for control of pollutant emissions. The experiment consists of a multisector, liquid-fueled combustor rig operated at different inlet pressures and temperatures, and over a range of fuel/air and water/fuel ratios. Fuel can be injected directly into the main combustion airstream and into the cavities. Test rig performance is characterized by combustor exit quantities such as temperature and emissions measurements using rakes and overall pressure drop from upstream plenum to combustor exit. Visualization of the flame is performed using gray scale and color still photographs and high-frame-rate videos. CFD simulations are performed utilizing a methodology that includes computer-aided design (CAD) solid modeling of the geometry, parallel processing over networked computers, and graphical and quantitative post-processing. Physical models include liquid fuel droplet dynamics and evaporation, with combustion modeled using a hybrid finite-rate chemistry model developed for Jet-A fuel. CFD and experimental results are compared for cases with cavity-only fueling, while numerical studies of cavity and main fueling was also performed. Predicted and measured trends in combustor exit temperature, CO and NOx are in general agreement at the different water/fuel loading rates, although quantitative differences exist between the predictions and measurements.

Brankovic, A.; Ryder, R. C., Jr.; Hendricks, R. C.; Liu, N.-S.; Shouse, D. T.; Roquemore, W. M.

2005-01-01

380

Investigating the solid-liquid phase transition of water nanofilms using the generalized replica exchange method.  

PubMed

The generalized Replica Exchange Method (gREM) was applied to study a solid-liquid phase transition in a nanoconfined bilayer water system using the monatomic water (mW) model. Exploiting optimally designed non-Boltzmann sampling weights with replica exchanges, gREM enables an effective sampling of configurations that are metastable or unstable in the canonical ensemble via successive unimodal energy distributions across phase transition regions, often characterized by S-loop or backbending in the statistical temperature. Extensive gREM simulations combined with Statistical Temperature Weighted Histogram Analysis Method (ST-WHAM) for nanoconfined mW water at various densities provide a comprehensive characterization of diverse thermodynamic and structural properties intrinsic to phase transitions. Graph representation of minimized structures of bilayer water systems determined by the basin-hopping global optimization revealed heterogeneous ice structures composed of pentagons, hexagons, and heptagons, consistent with an increasingly ordered solid phase with decreasing density. Apparent crossover from a first-order solid-liquid transition to a continuous one in nanoconfined mW water with increasing density of the system was observed in terms of a diminishing S-loop in the statistical temperature, smooth variation of internal energies and heat capacities, and a characteristic variation of lateral radial distribution functions, and transverse density profiles across transition regions. PMID:25399190

Lu, Qing; Kim, Jaegil; Farrell, James D; Wales, David J; Straub, John E

2014-11-14

381

Investigating the solid-liquid phase transition of water nanofilms using the generalized replica exchange method  

NASA Astrophysics Data System (ADS)

The generalized Replica Exchange Method (gREM) was applied to study a solid-liquid phase transition in a nanoconfined bilayer water system using the monatomic water (mW) model. Exploiting optimally designed non-Boltzmann sampling weights with replica exchanges, gREM enables an effective sampling of configurations that are metastable or unstable in the canonical ensemble via successive unimodal energy distributions across phase transition regions, often characterized by S-loop or backbending in the statistical temperature. Extensive gREM simulations combined with Statistical Temperature Weighted Histogram Analysis Method (ST-WHAM) for nanoconfined mW water at various densities provide a comprehensive characterization of diverse thermodynamic and structural properties intrinsic to phase transitions. Graph representation of minimized structures of bilayer water systems determined by the basin-hopping global optimization revealed heterogeneous ice structures composed of pentagons, hexagons, and heptagons, consistent with an increasingly ordered solid phase with decreasing density. Apparent crossover from a first-order solid-liquid transition to a continuous one in nanoconfined mW water with increasing density of the system was observed in terms of a diminishing S-loop in the statistical temperature, smooth variation of internal energies and heat capacities, and a characteristic variation of lateral radial distribution functions, and transverse density profiles across transition regions.

Lu, Qing; Kim, Jaegil; Farrell, James D.; Wales, David J.; Straub, John E.

2014-11-01

382

Evaporation Rates for Liquid Water and Ice Under Current Martian Conditions  

NASA Technical Reports Server (NTRS)

A number of studies have been concerned with the evaporation rates under martian conditions in order to place limits on the possible survival time of both liquid water and ice exposed on the surface of Mars. Such studies also aid in assessing the efficacy of an overlying layer of dust or loose regolith material in providing a barrier to free evaporation and thus prolong the lifetime of water in locations where its availability to putative living organisms would be significant. A better quantitative understanding of the effects of phase changes of water in the near surface environment would also aid the evaluation of the possible role of water in the formation of currently observed features, such as gullies in cliff walls and relatively short-term changes in the albedo of small surface areas ('dark stains'). Laboratory measurements aimed at refinement of our knowledge of these values are described here. The establishment of accurate values for evaporation rates and their dependence on the physical conditions of temperature, pressure and energy input, is an important benchmark for the further investigation of the efficacy of barriers to free evaporation in providing a prolonged period of survival of the water, particularly as a liquid.

Sears, D. W. G.; Moore, S. R.; Meier, A.; Chittenden, J.; Kareev, M.; Farmer, C. B.

2004-01-01

383

High-accuracy measurement of low-water-content in liquid using NIR spectral absorption method  

NASA Astrophysics Data System (ADS)

Water content measurement technologies are very important for quality inspection of food, medicine products, chemical products and many other industry fields. In recent years, requests for accurate low-water-content measurement in liquid are more and more exigent, and great interests have been shown from the research and experimental work. With the development and advancement of modern production and control technologies, more accurate water content technology is needed. In this paper, a novel experimental setup based on near-infrared (NIR) spectral technology and fiber-optic sensor (OFS) is presented. It has a good measurement accuracy about -/+ 0.01%, which is better, to our knowledge, than most other methods published until now. It has a high measurement resolution of 0.001% in the measurement range from zero to 0.05% for water-in-alcohol measurement, and the water-in-oil measurement is carried out as well. In addition, the advantages of this method also include pollution-free to the measured liquid, fast measurement and so on.

Peng, Bao-Jin; Wan, Xu; Jin, Hong-Zhen; Zhao, Yong; Mao, He-Fa

2005-01-01

384

Zero Liquid Discharge (ZLD) System for Flue-Gas Derived Water From Oxy-Combustion Process  

SciTech Connect

Researchers at the National Energy Technology Laboratory (NETL) located in Albany, Oregon, have patented a process - Integrated Pollutant Removal (IPR) that uses off-the-shelf technology to produce a sequestration ready CO{sub 2} stream from an oxy-combustion power plant. Capturing CO{sub 2} from fossil-fuel combustion generates a significant water product which can be tapped for use in the power plant and its peripherals. Water condensed in the IPR{reg_sign} process may contain fly ash particles, sodium (from pH control), and sulfur species, as well as heavy metals, cations and anions. NETL is developing a treatment approach for zero liquid discharge while maximizing available heat from IPR. Current treatment-process steps being studied are flocculation/coagulation, for removal of cations and fine particles, and reverse osmosis, for anion removal as well as for scavenging the remaining cations. After reverse osmosis process steps, thermal evaporation and crystallization steps will be carried out in order to build the whole zero liquid discharge (ZLD) system for flue-gas condensed wastewater. Gypsum is the major product from crystallization process. Fast, in-line treatment of water for re-use in IPR seems to be one practical step for minimizing water treatment requirements for CO{sub 2} capture. The results obtained from above experiments are being used to build water treatment models.

Sivaram Harendra; Danylo Oryshchyn; Thomas Ochs; Stephen J. Gerdemann; John Clark

2011-10-16

385

Water-clustering in hygroscopic ionic liquids-an implicit solvent analysis.  

PubMed

Most ionic liquids are known to be hygroscopic to varying degrees, and that can be detrimental or useful depending upon the application in question. Water can accumulate slowly over hours or days to saturation levels corresponding to the humidity level. When designing or deploying a new ionic liquid it is important to be able to estimate its maximum moisture absorbing ability at the temperature and pressure of its operation. With this goal in mind we have carried out computational studies on three ionic liquid systems based on [BF(4)](-), [PF(6)](-), and [Tf(2)N](-) anions and 1-alkyl-3-methyl-imidazolium ([C(n)mim](+)) cations within an implicit solvent formalism. For highly hygroscopic systems like [C(n)mim][BF(4)] we find that non-iterative calculations with single water molecules can lead to significant underestimation of the maximum moisture content, while iterative calculations can result in miscibility behavior qualitatively different from experimental observations. On the other hand, the inclusion of small hydrogen-bonded water-clusters up to an appropriately chosen size is shown to yield better quantitative agreements with experimentally observed water uptake. Additionally, such calculations appear consistent with a number of thermodynamically interesting phase behaviors, including limited-solubility to full-miscibility transitions as a function of temperature and as a function of the alkyl chain length of the imidazolium cation. For hydrophobic systems like [C(n)mim][PF(6)] and [C(n)mim][Tf(2)N] the computed solubility (for each n) is found to have a smooth convergence behavior as a function of the largest cluster-size considered with the results for the larger clusters being close to that obtained by iterative calculations with single water molecules. PMID:22415547

Maiti, Amitesh; Kumar, Arvind; Rogers, Robin D

2012-04-21

386

Detection of stanozolol in environmental waters using liquid chromatography tandem mass spectrometry  

PubMed Central

Background Owing to frequent administration of a wide range of pharmaceutical products, various environmental waters have been found to be contaminated with pharmacologically active substances. For example, stanozolol, a synthetic anabolic steroid, is frequently misused for performance enhancement as well as for illegal growth promoting purposes in veterinary practice. Previously we reported stanozolol in hair samples collected from subjects living in Budapest. For this reason we initiated this study to explore possible environmental sources of steroid contamination. The aim of this study was to develop a method to monitor stanozolol in aqueous matrices using liquid chromatography tandem mass spectrometry (LC-MS/MS). Results Liquid-liquid extraction using pentane was found to be an efficient method for the extraction of stanozolol from water samples. This was followed by direct detection using LC-MS/MS. The method was capable of detecting 0.25 pg/mL stanozolol when only 5 mL water was processed in the presence of stanozolol D3 as internal standard. Fifteen bottled waters analysed were found to be negative for stanozolol. However, three out of six samples from the Danube river, collected from December '09 to November '10, were found to contain stanozolol at concentrations up to 1.82 pg/mL. In contrast, only one sample (out of six) of urban tap water from Budapest city was found to contain stanozolol, at a concentration of 1.19 pg/mL. Conclusion The method developed is efficient, rapid, reproducible, sensitive and robust for the detection of stanozolol in aqueous matrices. PMID:21999747

2011-01-01

387

Molecular dynamics simulations of kinetic isotope fractionation during the diffusion of ionic species in liquid water  

NASA Astrophysics Data System (ADS)

Interpretation of isotope ratios, a powerful tool in geochemical investigations of fluid-rock systems, requires an understanding of all relevant processes that fractionate isotopes. One such process, diffusion in liquid water, has remained problematic despite its potential significance as a major cause of kinetic isotope fractionation. Recent laboratory experiments published by [Richter, F. M., Mendybaev, R. A., Christensen, J. N., Hutcheon, I. D., Williams, R. W., Sturchio, N. C., and Beloso Jr., A. D. (2006) Kinetic isotopic fractionation during diffusion of ionic species in water. Geochim. Cosmochim. Acta70, 277-289.] have shown clearly for the first time that lithium and chloride isotopes are fractionated by diffusion in liquid water, whereas magnesium isotopes are not. In the present paper, we present the results of molecular dynamics simulations of lithium, chloride, and magnesium diffusion in liquid water that were designed to provide molecular-scale insight into the experimental findings of Richter et al. (2006). Our results indicate that the self-diffusion coefficients of lithium, chloride, and magnesium isotopes follow an inverse power-law dependence on ion mass ( Di?mi-?, where Di is the self-diffusion coefficient of a solute with isotopic mass mi). The power-law exponents ( ?) deduced for lithium, chloride, and magnesium from the diffusivity data of Richter et al. (2006) are consistent with the mass dependencies found in our simulations. Further analysis of our simulation results showed that the experimental ?-values are inversely related to the residence times of water molecules in the first solvation shells of the diffusing ions, as expected from mode-coupling and renormalized kinetic theories.

Bourg, Ian C.; Sposito, Garrison

2007-12-01

388

Estimating Entropy of Liquids from Atom-Atom Radial Distribution Functions: Silica, Beryllium Fluoride and Water  

E-print Network

Molecular dynamics simulations of water, liquid beryllium fluoride and silica melt are used to study the accuracy with which the entropy of ionic and molecular liquids can be estimated from atom-atom radial distribution function data. All three systems are known to display similar liquid-state thermodynamic and kinetic anomalies due to a region of anomalous excess entropy behaviour where entropy rises on isothermal compression. The pair correlation entropy is demonstrated to be sufficiently accurate that the density-temperature regime of anomalous behaviour as well as the strength of the entropy anomaly can be predicted reliably for both ionic melts as well as different rigid-body pair potentials for water. Errors in the total thermodynamic entropy for ionic melts due to the pair correlation approximation are of the order of 10% or less for most state points but can be significantly larger in the anomalous regime at very low temperatures. In the case of water, as expected given the rigid-body constraints for a molecular liquids, the pair correlation approximation causes significantly larger errors, between 20 and 30%, for most state points. Comparison of the excess entropy, Se, of ionic melts with the pair correlation entropy, S2, shows that the temperature dependence of Se is well described by T ??2=5 scaling across both the normal and anomalous regimes, unlike in the case of S2. As a function of density, the Se(rho) curves shows only a single maximum while the S2(rho) curves show both a maximum and a minimum. These differences in the behaviour of S2 and Se are due to the fact that the residual multiparticle entropy, delta(S) = Se - S2, shows a strong negative correlation with tetrahedral order in the anomalous regime.

Ruchi Sharma; Manish Agarwal; Charusita Chakravarty

2008-05-23

389

Analysis of two independent methods for retrieving liquid water profiles in spring and summer Arctic boundary clouds  

E-print Network

Analysis of two independent methods for retrieving liquid water profiles in spring and summer number of all-liquid, nondrizzling stratus clouds (163 hours of measurements) were observed with a dual-channel microwave radiometer and a colocated 35-GHz cloud radar during the spring and summer months of the Surface

Shupe, Matthew

390

A new retrieval for cloud liquid water path using a ground-based microwave radiometer and measurements of cloud temperature.  

SciTech Connect

A new method to retrieve cloud liquid water path using 23.8 and 31.4 GHz microwave radiometer brightness temperature measurements is developed. This method does not depend on climatological estimates of either the mean radiating temperature of the atmosphere T{sub mr} or the mean cloud liquid water temperature T{sub cloud}. Rather, T{sub mr} is estimated from surface temperature and relative humidity measurements, while T{sub cloud} is estimated using millimeter-wave cloud radar data, together with atmospheric temperature profiles obtained from either radiosonde or rapid update cycle (RUC) model output. Simulations demonstrate that the new retrieval method significantly reduces the biases in the liquid water path estimates that are apparent in a site-specific retrieval based on monthly stratified, local climatology. An analysis of the liquid water path estimates produced by the two retrievals over four case study days illustrates trends and retrieval performances consistent with the model simulations.

Liljegren, J. C.; Clothiaux, E. E.; Mace, G. G.; Kato, S.; Dong, X.; Environmental Research; Pennsylvania State Univ.; Univ. of Utah; Hampton Univ.

2001-07-16

391

Removal of pharmaceuticals from water: using liquid-core microcapsules as a novel approach.  

PubMed

In recent years ever-increasing amounts of pharmaceuticals are being detected in the aquatic environment and in some cases, they have even been discovered in drinking water. Their presence is attributed mainly to the inability of sewage treatment plants to adequately remove these compounds from the sewage influent. The aim of this study was to investigate the feasibility, kinetics and efficiency of using liquid-core microcapsules as a novel methodology, termed capsular perstraction, to remove seven pharmaceuticals commonly found in the environment, from water. The process involves the envelopment of pre-selected organic solvents within a porous hydrogel membrane to form liquid-core microcapsules, which can be used to extract a large range of compounds. Results indicate that this novel approach is capable of extracting the seven chosen compounds rapidly and with a variable efficiency. The simultaneous use of both dibutyl sebacate and oleic acid liquid-core microcapsules at a liquid volume ratio of only 4% (v/v) resulted in the following extractions within 50min of capsule addition to contaminated water: furosemide 15%; clofibric acid 19%; sulfamethoxazole 22%; carbamazepine 54%; warfarin 80%; metoprolol 90% and diclofenac 100%. The effects of different agitation rates, microcapsule size and membrane thickness on the rate of mass transfer of warfarin into the liquid-core (dibutyl sebacate) of microcapsules was also examined. Results showed that the main rate-limiting step to mass transfer was due to the stagnant organic film (microcapsule size) within the core of the microcapsules. A volumetric mass transfer coefficient of 2.28x10(-6)m/s was obtained for the smallest microcapsules, which was nearly 4-fold higher compared to the value (0.6x10(-6)m/s) obtained for the largest microcapsules used in this study. Even with this resistance liquid-core microcapsules are still capable of the rapid extraction of the tested compounds and may provide a platform for the safe disposal of the pharmaceuticals after removal. PMID:20163817

Whelehan, Micheal; von Stockar, Urs; Marison, Ian W

2010-04-01

392

Water-Exclusion and Liquid-Structure Forces in Implicit Solvation  

PubMed Central

A continuum model of solvation is proposed to describe: i) long-range electrostatic effects of water exclusion resulting from incomplete and anisotropic hydration in crowded environments, and ii) short-range effects of liquid-structure forces on the hydrogen-bond interactions at solute/water interfaces. The model is an extension of the phenomenological screened Coulomb potential-based implicit model of solvation. The developments reported here allow a more realistic representation of highly crowded and spatially heterogeneous environments, such as those in the interior of a living cell. Only the solvent is treated as a continuum medium. It is shown that the electrostatic effects of long-range water-exclusion can strongly affect protein-protein binding energies and are then related to the thermodynamics of binding. Hydrogen-bond interactions modulated by the liquid structure at interfaces are calibrated based on systematic calculations of potentials of mean force in explicit water. The electrostatic component of the model is parameterized for monovalent, divalent and trivalent ions. The conceptual and practical aspects of the model are discussed based on simulations of protein complexation and peptide folding. The current implementation is ~1.5 times slower than the gas-phase force field and exhibits good parallel performance. PMID:22007697

Hassan, Sergio A.; Steinbach, Peter J.

2012-01-01

393

Developing polarizable potential for molecular dynamics of Cm(III)-carbonate complexes in liquid water.  

PubMed

In this work we have developed a polarizable potential to study Cm(III) forming complexes with carbonate anions in liquid water. The potential was developed by employing an extension of the procedure that we used to study the hydration of lanthanoids(III) and actinoids(III). Force field performances were benchmarked against DFT results obtained by both geometry optimization and Car-Parrinello molecular dynamics. With this polarizable potential, we run extended molecular dynamics simulations in liquid water from which we were able to identify structural and dynamical properties of such systems. In particular, water exchange dynamics were analyzed in detail. We obtained an average of three water molecules in the first shell of Cm(III) that show a relatively fast exchange dynamic (faster than for bare ions). Summarizing these results, we were able to draw an analogy to the results from the lanthanoid(III) series. In particular, it seems that Cm(III) behaves more like Nd(III) than Gd(III), as one would expect based on the recent hydration results and on f orbital occupancy. PMID:25086768

Spezia, Riccardo; Jeanvoine, Yannick; Vuilleumier, Rodolphe

2014-08-01

394

Collective rotations of ferroelectric liquid crystals at the air/water interface.  

PubMed

We study the Langmuir monolayers of four different ferroelectric liquid crystals on water surface. Two of them are attached to water surface by their polar groups, and the chiral groups, at the opposite ends of the elongated molecules, remain well above the interface. The other two ferroelectrics have both groups (polar and chiral) at close proximity, and therefore the chiral group is also attached to the surface or even submerged in water. We demonstrate that only when the chiral group of the ferroelectric liquid crystal in Langmuir monolayer is not attached to the interface and stays in the air does the system exhibit the collective rotations induced by evaporation of water (described for the first time by: Tabe, Y.; Yokoyama, H. Nat. Mater. 2003, 2, 806). The isotherms of surface pressure and surface potential versus molecular area of four compounds were measured with simultaneous observations using Brewster angle microscopy. Experimental data of the compression isotherms are described with a van der Waals model with very good accuracy, and the fitted parameters were used for calculations of compressibility coefficients for different phases found in the compounds under investigations. The ability of the two compounds for rotation and the disability of the two others is discussed in a context of thermodynamic properties of the monolayers. PMID:18826262

Milczarczyk-Piwowarczyk, Patrycja; Zywoci?ski, Andrzej; Noworyta, Krzysztof; Ho?yst, Robert

2008-11-01

395

Interaction of Cellulose Chains with Ionic Liquids and Water via MD simulations  

NASA Astrophysics Data System (ADS)

One promising route for combustible fuel sources which are both renewable and have a low environmental impact is the conversion of waste biomass into tailor-made fuels. An important aspect of this process is the low-energy separation of cellulose from the biomass. Ionic liquids (ILs) have proven to be very good in dissolving cellulose with the added benefit of being essentially non-volatile making them ideal for ``green'' processing. IL research, however, remains relatively new, with many parts of this dissolution process remaining uncertain. We examine the behavior of cellulose with the ionic liquids [BMIM]Cl, [EMIM]Ac and [DMIM]DMP as well as water via MD simulation. All three ionic liquids have been observed to dissolve cellulose quite well yet have differently sized anions. We explore these differences and the impacts they have on their interactions with cellulose. First we examine the dynamics of a single cellulose strand in these ionic liquids. We determine the radius of gyration and the hydrogen bonds that are formed between the anions and cellulose. Next, we probe the dissolution mechanism of multiple, bound cellulose strands examining of multiple, bound cellulose strands examining interactions at the IL/cellulose interface and the breakup of inter-cellulose hydrogen bonds.

Ismail, Ahmed; Rabideau, Brooks

2012-02-01

396

Interfacial liquid water on Mars and its potential role in formation of hill and dune gullies  

NASA Astrophysics Data System (ADS)

Gullies are among the most intriguing structures identified on the surface of Mars. Most common are gullies located on the slopes of craters which are probably formed by liquid water transported by shallow aquifers (Heldmann, J.L., Carlsson, E., Johansson, H., Mellon, M.T., Toon, O.B. [2007]. Icarus 188, 324-344). Two particular types of gullies are found on slopes of isolated hills and dunes. The hill-slope gullies are located mostly at 50°S, which is at the high end of latitudes of bulk of the gullies found so far. The dune gullies are found in several locations up to 65°S (Reiss, D., Jaumann, R., Kereszturi, A., Sik, A., Neukum, G. [2007]. Lunar Planet. Sci. XXXVIII. Abstract 1993), but the best known are those in Russel crater at 54°S. The hill and dune gullies are longer than others making the aquifers explanation for their formation unlikely (Balme, M., Mangold, N., Baratoux, D., Costard, F., Gosselin, M., Masson, P., Pnet, P., Neukum, G. [2006]. J. Geophys. Res. 111. doi:10.1029/2005JE002607). Recently it has been noted that thin liquid films of interfacial water can play a role in rheological processes on the surface of Mars (Moehlmann, D. [2008]. Icarus 195, 131-139. Kereszturi, A., Moehlmann, D., Berczi, Sz., Ganti, T., Kuti, A., Sik, A., Horvath, A. [2009]. Icarus 201, 492-503.). Here we try to answer the question whether interfacial liquid water may occur on Mars in quantities large enough to play a role in formation of gullies. To verify this hypothesis we have calculated thermal models for hills and dunes of various steepness, orientation and physical properties. We find that within a range of average expected values of parameters it is not possible to have more than a few monolayers of liquid water at depths greater than a centimeter. To create subsurface interfacial water film significantly thicker and hence to produce conditions for the slope instability, parameters have to be chosen to have their extreme realistic values or an additional source of surface heating is needed. One possibility for additional heating is a change of atmospheric conditions due to a local dust storm. We conclude that if interfacial water is responsible for the formation of the hill-slope gullies, our results may explain why the hill gullies are rare.

Kossacki, Konrad J.; Markiewicz, Wojciech J.

2010-11-01

397

Response of soybean rhizosphere communities to human hygiene water addition as determined by community level physiological profiling (CLPP) and terminal restriction fragment length polymorphism (TRFLP) analysis.  

PubMed

In this report, we describe an experiment conducted at Kennedy Space Center in the biomass production chamber (BPC) using soybean plants for purification and processing of human hygiene water. Specifically, we tested whether it was possible to detect changes in the root-associated bacterial assemblage of the plants and ultimately to identify the specific microorganism(s) which differed when plants were exposed to hygiene water and other hydroponic media. Plants were grown in hydroponics media corresponding to four different treatments: control (Hoagland's solution), artificial gray water (Hoagland's+surfactant), filtered gray water collected from human subjects on site, and unfiltered gray water. Differences in rhizosphere microbial populations in all experimental treatments were observed when compared to the control treatment using both community level physiological profiles (BIOLOG) and molecular fingerprinting of 16S rRNA genes by terminal restriction fragment length polymorphism analysis (TRFLP). Furthermore, screening of a clonal library of 16S rRNA genes by TRFLP yielded nearly full length SSU genes associated with the various treatments. Most 16S rRNA genes were affiliated with the Klebsiella, Pseudomonas, Variovorax, Burkholderia, Bordetella and Isosphaera groups. This molecular approach demonstrated the ability to rapidly detect and identify microorganisms unique to experimental treatments and provides a means to fingerprint microbial communities in the biosystems being developed at NASA for optimizing advanced life support operations. PMID:10689173

Kerkhof, L; Santoro, M; Garland, J

2000-03-01

398

Nanoparticle enhanced evaporation of liquids: A case study of silicone oil and water  

NASA Astrophysics Data System (ADS)

Evaporation is a fundamental physical phenomenon, of which many challenging questions remain unanswered. Enhanced evaporation of liquids in some occasions is of enormous practical significance. Here we report the enhanced evaporation of the nearly permanently stable silicone oil by dispersing with nanopariticles including CaTiO3, anatase and rutile TiO2. An evaporation rate as high as 1.33 mg/h.cm2 was measured in silicone oil when dispersed with 100 nm-sized CaTiO3 particles. Dependence of evaporation rate on the chemistry, size and structure of the particles suggests that some weak absorption sites on the particles half floating on the liquid surface are responsible for the facilitated evaporation of liquid molecules. Enhanced evaporation is also observed for water when dispersed with anatase TiO2 particles. The results can inspire the research of atomistic mechanism for nanoparticle enhanced evaporation and exploration of evaporation control techniques for treatment of oil pollution and restoration of dirty water.

Zhang, Wenbin; Shen, Rong; Lu, Kunquan; Ji, Ailing; Cao, Zexian

2012-12-01

399

Comparisons of Calculations with PARTRAC and NOREC: Transport of Electrons in Liquid Water  

PubMed Central

Monte Carlo computer models that simulate the detailed, event-by-event transport of electrons in liquid water are valuable for the interpretation and understanding of findings in radiation chemistry and radiation biology. Because of the paucity of experimental data, such efforts must rely on theoretical principles and considerable judgment in their development. Experimental verification of numerical input is possible to only a limited extent. Indirect support for model validity can be gained from a comparison of details between two independently developed computer codes as well as the observable results calculated with them. In this study, we compare the transport properties of electrons in liquid water using two such models, PARTRAC and NOREC. Both use interaction cross sections based on plane-wave Born approximations and a numerical parameterization of the complex dielectric response function for the liquid. The models are described and compared, and their similarities and differences are highlighted. Recent developments in the field are discussed and taken into account. The calculated stopping powers, W values, and slab penetration characteristics are in good agreement with one another and with other independent sources. PMID:18439039

Dingfelder, M.; Ritchie, R. H.; Turner, J. E.; Friedland, W.; Paretzke, H. G.; Hamm, R. N.

2013-01-01

400

Dynamical modeling of deep water type cylindrical tuned liquid damper with a submerged net  

SciTech Connect

An analytical model for describing the effectiveness of a deep water type cylindrical Tuned Liquid Damper (TLD) with a submerged net for suppressing horizontal vibration of structures is first proposed. In this study, the authors performed calculations to estimate the effectiveness of a deep water type cylindrical TLD based on a proposed dynamical model and compared with experimental results obtained by shaking table experiments and free oscillation tests. In particular, the effect of hydraulic resistance produced by a submerged net and the liquid depth ratio which means the ratio of the liquid depth to the diameter of the cylindrical tank are examined intensively. In the analysis, employing finite amplitude wave theory and Galerkin method in the case of cylindrical tank, they obtained hydrodynamic forces and the free surface elevations. Then, combining the hydrodynamic forces with the equation of motion of the structure, damped transient responses were calculated. The calculated results thus obtained were compared with the experimental results, by which the validity of the modeling methodology was confirmed.

Kaneko, Shigehiko [Univ. of Tokyo (Japan). Dept. of Mechanical Engineering; Mizota, Yasuo [Bridgestone Co., Ltd., Tokyo (Japan)

1996-12-01

401

Evaluation of the rate of uptake of nitrogen dioxide by atmospheric and surface liquid water  

SciTech Connect

The rate of uptake of NO/sub 2/ by liquid water according to (R1), 2NO/sub 2/(g)+H/sub 2/O(l)..-->..2H+NO/sub 3//sup -/+NO/sub 2//sup -/, is shown to be unaffected by O/sub 2/(0.2 atm). Hence the rate constant and Henry's law solubility constant of NO/sub 2/ previously obtained may be employed to evaluate the rates of aqueous phase reactions of NO/sub 2/ in the ambient atmosphere. Reactions (R1) and (R2), NO/sub 2/(g)+NO(g)+H/sub 2/O(l)..-->..2H/sup +/+2NO/sub 2//sup -/, are quite slow at representative atmospheric partial pressures and cloud liquid water content; the characteristic times range upward from 10/sup 3/--10/sup 4/ hours at 10/sup -7/ atm, increasing with decreasing partial pressures of the gases. Direct acidification of cloud liquid water by (R1) or (R2) is also unimportant. Catalytic enhancement of (R1) is potentially important for catalyst concentrations of order 10/sup -7/ M, assuming sufficiently fast rate constants (approx.10/sup 8/ M/sup -1/s/sup -1/). Iron-catalyzed reaction in particular, however, is found to be unimportant. Reaction of NO/sub 2/ with dissolved S(IV) is potentially important, based upon an assumed upper limit rate constant of 2.5 x 10/sup 7/ M/sup -1/ s/sup -1/. Deposition of NO/sub 2/ to surface (ocean or lake) water is shown to be controlled by aqueous phase mass transport and/or reaction and is much slower than heretofore assumed.

Lee, Y.; Schwartz, S.E.

1981-12-20

402

Molecular origin of the difference in the HOH bend of the IR spectra between liquid water and ice  

SciTech Connect

The intensity of the HOH bend in the IR spectrum of ice is significantly smaller than the corresponding one in liquid water. This difference in the IR intensities of the HOH bend in the two systems is investigated using MD simulations with the flexible, polarizable, ab-initio based TTM3-F model for water, a potential that correctly reproduces the experimentally observed increase of the HOH bend in liquid water and ice from the water monomer value. We have identified two factors that are responsible for the difference in the intensity of the HOH bend in liquid water and ice: (i) the decrease of the intensity of the HOH bend in ice caused by the strong anti-correlation between the permanent dipole moment of a molecule and the induced dipole moment of a neighboring hydrogen bond acceptor molecule and (ii) the weakening of this anti-correlation by the disordered hydrogen bond network in liquid water. The presence of the anti-correlation in ice is further confirmed by ab initio electronic structure calculations of water pentamer clusters extracted from the trajectories of the MD simulations for ice and liquid water.

Imoto, Sho; Xantheas, Sotiris S.; Saito, Shinji

2013-02-07

403

Molecular origin of the difference in the HOH bend of the IR spectra between liquid water and ice  

NASA Astrophysics Data System (ADS)

The intensity of the HOH bend in the infrared (IR) spectrum of ice is significantly smaller than the corresponding one in liquid water. This difference in the IR intensities of the HOH bend in the two systems is investigated using Molecular Dynamics (MD) simulations with the flexible, polarizable, ab initio based TTM3-F model for water, a potential that correctly reproduces the experimentally observed increase of the HOH angle in liquid water and ice from the water monomer value. We have identified two factors that are responsible for the difference in the intensity of the HOH bend in liquid water and ice: (i) the decrease of the intensity of the HOH bend in ice caused by the strong anti-correlation between the permanent dipole moment of a molecule and the induced dipole moment of neighboring hydrogen bond acceptor molecules, and (ii) the weakening of this anti-correlation by the disordered hydrogen bond network in liquid water. The presence of the anti-correlation in ice is further confirmed by ab initio electronic structure calculations of water pentamer clusters extracted from the trajectories of the MD simulations with the TTM3-F potential for ice and liquid water.

Imoto, Sho; Xantheas, Sotiris S.; Saito, Shinji

2013-02-01

404

Molecular origin of the difference in the HOH bend of the IR spectra between liquid water and ice.  

PubMed

The intensity of the HOH bend in the infrared (IR) spectrum of ice is significantly smaller than the corresponding one in liquid water. This difference in the IR intensities of the HOH bend in the two systems is investigated using Molecular Dynamics (MD) simulations with the flexible, polarizable, ab initio based TTM3-F model for water, a potential that correctly reproduces the experimentally observed increase of the HOH angle in liquid water and ice from the water monomer value. We have identified two factors that are responsible for the difference in the intensity of the HOH bend in liquid water and ice: (i) the decrease of the intensity of the HOH bend in ice caused by the strong anti-correlation between the permanent dipole moment of a molecule and the induced dipole moment of neighboring hydrogen bond acceptor molecules, and (ii) the weakening of this anti-correlation by the disordered hydrogen bond network in liquid water. The presence of the anti-correlation in ice is further confirmed by ab initio electronic structure calculations of water pentamer clusters extracted from the trajectories of the MD simulations with the TTM3-F potential for ice and liquid water. PMID:23406132

Imoto, Sho; Xantheas, Sotiris S; Saito, Shinji

2013-02-01

405

Method and apparatus for electrokinetic co-generation of hydrogen and electric power from liquid water microjets  

DOEpatents

A method and apparatus for producing both a gas and electrical power from a flowing liquid, the method comprising: a) providing a source liquid containing ions that when neutralized form a gas; b) providing a velocity to the source liquid relative to a solid material to form a charged liquid microjet, which subsequently breaks up into a droplet spay, the solid material forming a liquid-solid interface; and c) supplying electrons to the charged liquid by contacting a spray stream of the charged liquid with an electron source. In one embodiment, where the liquid is water, hydrogen gas is formed and a streaming current is generated. The apparatus comprises a source of pressurized liquid, a microjet nozzle, a conduit for delivering said liquid to said microjet nozzle, and a conductive metal target sufficiently spaced from said nozzle such that the jet stream produced by said microjet is discontinuous at said target. In one arrangement, with the metal nozzle and target electrically connected to ground, both hydrogen gas and a streaming current are generated at the target as it is impinged by the streaming, liquid spray microjet.

Saykally, Richard J; Duffin, Andrew M; Wilson, Kevin R; Rude, Bruce S

2013-02-12

406

A two-dimensional computational model of a PEMFC with liquid water transport  

NASA Astrophysics Data System (ADS)

A comprehensive, steady-state, computational model of a proton exchange membrane fuel cell (PEMFC) derived from first principles is presented. The model is two-dimensional and includes the transport of liquid water within the porous electrodes as well as the transport of gaseous species, protons, energy, and water dissolved in the ion conducting polymer. Electrochemical kinetics are modeled with standard rate equations adapted to an agglomerate catalyst layer structure. Some of the physical properties used in constructing the model are determined experimentally for an in-house membrane electrode assembly (MEA) and are presented herein. Experimental results obtained for the MEA are used to validate the computational model. Modeling results are presented that illustrate the importance of the transport of water within the porous sections of the cell and in the polymer regions of the MEA.

Siegel, N. P.; Ellis, M. W.; Nelson, D. J.; von Spakovsky, M. R.

407

Modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction followed by atomic absorption spectrometry for trace determination of zinc in water and food samples  

Microsoft Academic Search

We report on a new method for the microextraction and determination of zinc (II). The ion is accumulated via ionic-liquid\\u000a cold-induced aggregation dispersive liquid-liquid microextraction (IL-CIA-DLLME) followed by flame atomic absorption spectrometry\\u000a (FAAS). The ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate is dispersed into a heated sample solution containing\\u000a sodium hexafluorophosphate as a common ion source. The solution is then placed in

Mohsen Zeeb; Mahdi Sadeghi

408

Avoidance of a water-soluble fraction of coal liquid by fathead minnows  

SciTech Connect

The behavioral response of fathead minnows Pimephales promelas to a water-soluble fraction (WSF) of coal liquid was evaluated in a nine-chambered circular tank (rosette). Groups of 36 fish each were tested to examine the effects of this complex organic mixture on a schooling species. Avoidance of all WSF concentrations with greater than 1.7 mg/L phenols (dye photometric measurements) occurred in 96 h replicated test series. Fish preference data were used to estimate a median avoidance concentration (AC50) of 1.54 mg/L total phenols. The observed avoidance threshold was sufficient to protect the species from acutely lethal effects reported for this coal liquid WSF, but exceeded concentrations known to be chronically toxic. 26 references, 4 figures, 1 table.

Dauble, D.D.; Gray, R.H.; Skalaski, J.R.; Lusty, E.W.; Simmons, M.A.

1985-01-01

409

Thermally excited capillary waves at vapor/liquid interfaces of water-alcohol mixtures  

E-print Network

The density profiles of liquid/vapor interfaces of water-alcohol (methanol, ethanol and propanol) mixtures were studied by surface sensitive synchrotron X-ray scattering techniques. X-ray reflectivity and diffuse scattering measurements, from the pure and mixed liquids, were analyzed in the framework of capillary-wave theory to address the characteristics length-scales of the intrinsic roughness and the shortest capillary-wavelength (alternatively, the upper wave-vector cutoff in capillary wave theory). Our results establish that the intrinsic roughness is dominated by average interatomic distances. The extracted effective upper wave-vector cutoff indicates capillary wave theory breaks-down at distances on order of bulk correlation lengths.

David Vaknin; Wei Bu; Jaeho Sung; Yoonnam Jeon; Doseok Kim

2009-04-15

410

Geminal Br?nsted Acid Ionic Liquids as Catalysts for the Mannich Reaction in Water  

PubMed Central

Quaternary ammonium geminal Brønsted acid ionic liquids (GBAILs) based on zwitterionic 1,2-bis[N-methyl-N-(3-sulfopropyl)-alkylammonium]ethane (where the carbon number of the alkyl chain is 4, 8, 10, 12, 14, 16, or 18) and p-toluenesulfonic acid monohydrate were synthesized. The catalytic ionic liquids were applied in three-component Mannich reactions with an aldehyde, ketone, and amine at 25 °C in water. The effects of the type and amount of catalyst and reaction time as well as the scope of the reaction were investigated. Results showed that GBAIL-C14 has excellent catalytic activity and fair reusability. The catalytic procedure was simple, and the catalyst could be recycled seven times via a simple separation process without noticeable decreases in catalytic activity. PMID:24837832

He, Leqin; Qin, Shenjun; Chang, Tao; Sun, Yuzhuang; Zhao, Jiquan

2014-01-01

411

Rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection.  

PubMed

A method for the rapid pretreatment and determination of bisphenol A in water samples based on vortex-assisted liquid-liquid microextraction followed by high-performance liquid chromatography with fluorescence detection was proposed in this paper. A simple apparatus consisting of a test tube and a cut-glass dropper was designed and applied to collect the floating extraction drop in liquid-liquid microextraction when low-density organic solvent was used as the extraction solvent. Solidification and melting steps that were tedious but necessary once the low-density organic solvent used as extraction solvent could be avoided by using this apparatus. Bisphenol A was selected as model pollutant and vortex-assisted liquid-liquid microextraction was employed to investigate the usefulness of the apparatus. High-performance liquid chromatography with fluorescence detection was selected as the analytical tool for the detection of bisphenol A. The linear dynamic range was from 0.10 to 100 ?g/L for bisphenol A, with good squared regression coefficient (r(2) = 0.9990). The relative standard deviation (n = 7) was 4.7% and the limit of detection was 0.02 ?g/L. The proposed method had been applied to the determination of bisphenol A in natural water samples and was shown to be economical, fast, and convenient. PMID:25047024

Yang, Xiao; Diao, Chun-Peng; Sun, Ai-Ling; Liu, Ren-Min

2014-10-01

412

[Determination of three phenolic compounds in water samples by solid phase extraction with microemulsion liquid chromatography].  

PubMed

A method for the determination of phenol, bisphenol A (BPA), 2,4-dichlorophenol in water samples based on solid-phase extraction with microemulsion liquid chromatography (MELC) was established. The water sample was acidified, and then cleaned-up by a C18 solid phase extraction cartridge. The separation was carried out on an Inertsil C18 (150 mm x 4.6 mm, 5 microm) with a gradient elution using a microemulsion (consisting of 3.0% sodium dodecyl sulfate (SDS), 6.0% butyl alcohol, 0.8% n-heptane, 90.2% (water + 0.5% acetic acid)) and acetonitrile as mobile phases at a flow rate of 1.0 mL/min and a detection wavelength of 280 nm. The detection limits (S/N = 3) of phenol, BPA, 2,4-dichlorophenol were 0.74, 8.0, 8.0 microg/L, respectively. Good linearities were achieved for the target compounds over the range of 0.1 - 10 mg/L. The spiked recoveries of three phenolic compounds in blank water samples) were 82.7%, 87.8%, 82.6% for phenol, BPA, 2,4-dichlorophenol respectively. The recoveries of target compounds in real water samples ranged from 85.7% to 113.2%. The developed method is simple, selective, sensitive and applicable for the analysis of environmental water samples. PMID:24369619

Qiu, Xiuzhen; Guo, Huishi; Chen, Buqing

2013-08-01

413

Liquid chromatographic method for determining the concentration of bisazir in water  

USGS Publications Warehouse

Barrier dams, traps, and lampricides are the techniques currently used by the Great Lakes Fishery Commission to control sea lampreys (Petromyzon marinus) in the Great Lakes. To augment these control techniques, a sterile-male-release research program was initiated at the Lake Huron Biological Station. Male sea lampreys were sterilized by intraperitoneal injection of the chemical sterilant P,P-bis(1-aziridinyl)-N-methylphosphinothioic amide (bisazir). An analytical method was needed to quantitate the concentration of bisazir in water and to routinely verify that bisazir (>25 ?g/L) does not persist in the treated effluent discharged from the sterilization facility to Lake Huron. A rapid, accurate, and sensitive liquid chromatographic (LC) method was developed for determining bisazir in water. Bisazir was dissolved in Lake Huron water; extracted and concentrated on a C18 solid-phase extraction column; eluted with methanol; and quantitated by reversed-phase LC using a C18 column, a mobile phase of 70% water and 30% methanol (v/v), and UV detection (205 nm). Bisazir retention time was 7-8 min; total run time was about 20 min. Method detection limit for bisazir dissolved in Lake Huron water was about 15 ?g/L. Recovery from Lake Huron water fortified with bisazir at 100 ?g/L was 94% (95% confidence interval, 90.2-98.2%).

Scholefield, Ronald J.; Slaght, Karen S.; Allen, John L.

1997-01-01

414

Measuring Snow Liquid Water Content with Low-Cost GPS Receivers.  

PubMed

The amount of liquid water in snow characterizes the wetness of a snowpack. Its temporal evolution plays an important role for wet-snow avalanche prediction, as well as the onset of meltwater release and water availability estimations within a river basin. However, it is still a challenge and a not yet satisfyingly solved issue to measure the liquid water content (LWC) in snow with conventional in situ and remote sensing techniques. We propose a new approach based on the attenuation of microwave radiation in the L-band emitted by the satellites of the Global Positioning System (GPS). For this purpose, we performed a continuous low-cost GPS measurement experiment at the Weissfluhjoch test site in Switzerland, during the snow melt period in 2013. As a measure of signal strength, we analyzed the carrier-to-noise power density ratio (C/N0) and developed a procedure to normalize these data. The bulk volumetric LWC was determined based on assumptions for attenuation, reflection and refraction of radiation in wet snow. The onset of melt, as well as daily melt-freeze cycles were clearly detected. The temporal evolution of the LWC was closely related to the meteorological and snow-hydrological data. Due to its non-destructive setup, its cost-efficiency and global availability, this approach has the potential to be implemented in distributed sensor networks for avalanche prediction or basin-wide melt onset measurements. PMID:25384007

Koch, Franziska; Prasch, Monika; Schmid, Lino; Schweizer, Jürg; Mauser, Wolfram

2014-01-01

415

New dual-frequency microwave technique for retrieving liquid water path over land  

NASA Astrophysics Data System (ADS)

We present and demonstrate a new methodology for retrieving liquid water path over land using satellite-based microwave observations. As input, the technique exploits Advanced Microwave Scanning Radiometer for EOS (AMSR-E) brightness temperature polarization-difference signals at 37 and 89 GHz. Regression analysis performed on model simulations indicates that over variable atmospheric and surface conditions these polarization-difference signals can be simply parameterized in terms of the surface emissivity polarization-difference (??), surface temperature, liquid water path (LWP), and precipitable water vapor (PWV). By exploiting the weak frequency dependence of ??, a simple expression is obtained which enables fast and direct (noniterative) retrievals of LWP. The new methodology is demonstrated and validated using several months of AMSR-E observations over (1) the Southern Great Plains (SGP) of the United States and (2) an area near Montreal, Canada, instrumented during the Alliance Icing Research Study II (AIRS II) field campaign. Comparisons are also made with MODIS LWP retrieval results for one scene over the SGP region. Retrieval results in clear-sky conditions indicate an uncertainty on the order of 0.06 mm, in agreement with theoretical estimates. In cloudy conditions, results using the new method are systematically smaller than results for both ground-based microwave radiometers and MODIS but are well correlated.

Deeter, M. N.; Vivekanandan, J.

2006-08-01

416

The first vadose zone partitioning interwell tracer test for nonaqueous phase liquid and water residual  

SciTech Connect

In 1995, a partitioning interwell tracer test was conducted in the vadose zone beneath two buried organic liquid disposal trenches at Sandia National Laboratories in New Mexico. The purpose was to estimate the amount and distribution of trichloroethylene (TCE) trapped by capillary forces as residual dense nonaqueous phase liquid (DNAPL). Screened injection and extraction wells, placed 16.8 m apart, and two monitor wells with multilevel sampling capability allowed vertical testing from 3.0 to 24.4 m below ground surface. Seven tracers were injected, but the most useful tracers in the final analysis were sulfur hexafluoride (nonpartitioning), perfluoro-1,3,5-trimethylcyclohexane (TCE-partitioning), and difluoromethane (water-partitioning). Both a TCE-partitioning tracer and a water-partitioning tracer were needed to determine average TCE DNAPL saturation. Average saturations of DNAPL and water were measured to be 0.11 {+-} 0.02% and 23 {+-} 2.0%, respectively, in the shallow zone between 3.0 and 10.7 m. Monitor well data showed no evidence of DNAPL below a depth of 9 m. These results had important implications for remedial actions at the site.

Mariner, P.E. [Duke Engineering and Services, Grand Junction, CO (United States)] [Duke Engineering and Services, Grand Junction, CO (United States); Jin, M. [Duke Engineering and Services, Austin, TX (United States)] [Duke Engineering and Services, Austin, TX (United States); Studer, J.E. [Duke Engineering and Services, Albuquerque, NM (United States)] [Duke Engineering and Services, Albuquerque, NM (United States); Pope, G.A. [Univ. of Texas, Austin, TX (United States). Center for Petroleum and Geosystems Engineering] [Univ. of Texas, Austin, TX (United States). Center for Petroleum and Geosystems Engineering

1999-08-15

417

Study of Aerosol Liquid Water Content based on Hygroscopicity Measurements at High Relative Humidity in the North China Plain  

NASA Astrophysics Data System (ADS)

Aerosol has significant effects on direct/indirect climate forcing, visibility, tropospheric chemistry and human health. Water can represent an extensive proportion of the mass of aerosol particles, and can also serve as a medium for aqueous-phase reactions in such particulate matter. In this study, a new method is proposed to estimate the aerosol liquid water content at high relative humidity, based on aerosol hygroscopic growth factors, particle number size distribution and relative humidity measured during the Haze in China (HaChi) campaign of July-August, 2009. The aerosol liquid water content estimated by this method is compared to the results calculated by a thermodynamic equilibrium model (ISORROPIA II). The calculation results from these two methods agree well at high relative humidity above 60% with the correlation coefficient of 0.9658. At relative humidity lower than 60%, the thermodynamic equilibrium model underestimates the aerosol liquid water content. The discrepancy is mainly caused by the ISORROPIA II model, which considers only limited chemical species. The mean and maximum value of aerosol liquid water content during July-August, 2009 in the North China Plain reached 1.69×10^{-4}g/m^3 and 9.71×10^{-4}g/m^3, respectively. Aerosol liquid water content is highly related to the relative humidity. There exists a distinct diurnal variation of the aerosol liquid water content, with lower values during daytime and higher ones during night time. The contribution to the aerosol liquid water content from the accumulation mode is dominating among all the aerosol particle modes.

Bian, Y.; Zhao, C.

2013-12-01

418

Electrochemical assessment of water|ionic liquid biphasic systems towards cesium extraction from nuclear waste.  

PubMed

A room temperature ionic liquid (IL) composed of a quaternary alkylphosphonium (trihexyltetradecylphosphonium, P66614(+)) and tetrakis(pentafluorophenyl)borate anion (TB(-)) was employed within a water|P66614TB (w|P66614TB or w|IL) biphasic system to evaluate cesium ion extraction in comparison to that with a traditional water|organic solvent (w|o) combination. (137)Cs is a major contributor to the radioactivity of spent nuclear fuel as it leaves the reactor, and its extraction efficiency is therefore of considerable importance. The extraction was facilitated by the ligand octyl(phenyl)-N,N'-diisobutylcarbamoylphosphine oxide (CMPO) used in TRans-Uranium EXtraction processes and investigated through well established liquid|liquid electrochemistry. This study gave access to the metal ion to ligand (1:n) stoichiometry and overall complexation constant, ?, of the interfacial complexation reaction which were determined to be 1:3 and 1.6×10(11) at the w|P66614TB interface while the study at w|o elicited an n equal to 1 with ? equal to 86.5. Through a straightforward relationship, these complexation constant values were converted to distribution coefficients, ?(?), with the ligand concentrations studied for comparison to other studies present in the literature; the w|o and w|IL systems gave ?(?) of 2 and 8.2×10(7), respectively, indicating a higher overall extraction efficiency for the latter. For the w|o system, the metal ion-ligand stoichiometries were confirmed through isotopic distribution analysis of mass spectra obtained by the direct injection of an emulsified water-organic solvent mixture into an electron spray ionization mass spectrometer. PMID:24703212

Stockmann, T Jane; Zhang, Jing; Montgomery, Anne-Marie; Ding, Zhifeng

2014-04-22

419

Inelastic cross sections for low-energy electrons in liquid water: exchange and correlation effects.  

PubMed

Low-energy electrons play a prominent role in radiation therapy and biology as they are the largest contributor to the absorbed dose. However, no tractable theory exists to describe the interaction of low-energy electrons with condensed media. This article presents a new approach to include exchange and correlation (XC) effects in inelastic electron scattering at low energies (below ?10 keV) in the context of the dielectric theory. Specifically, an optical-data model of the dielectric response function of liquid water is developed that goes beyond the random phase approximation (RPA) by accounting for XC effects using the concept of the many-body local-field correction (LFC). It is shown that the experimental energy-loss-function of liquid water can be reproduced by including into the RPA dispersion relations XC effects (up to second order) calculated in the time-dependent local-density approximation with the addition of phonon-induced broadening in N. D. Mermin's relaxation-time approximation. Additional XC effects related to the incident and/or struck electrons are included by means of the vertex correction calculated by a modified Hubbard formula for the exchange-only LFC. Within the first Born approximation, the present XC corrections cause a significantly larger reduction (?10-50%) to the inelastic cross section compared to the commonly used Mott and Ochkur approximations, while also yielding much better agreement with the recent experimental data for amorphous ice. The current work offers a manageable, yet rigorous, approach for including non-Born effects in the calculation of inelastic cross sections for low-energy electrons in liquid water, which due to its generality, can be easily extended to other condensed media. PMID:24131062

Emfietzoglou, Dimitris; Kyriakou, Ioanna; Garcia-Molina, Rafael; Abril, Isabel; Nikjoo, Hooshang

2013-11-01

420

Experimental measurement of variations in the optical reflection coefficient of water-magnetic liquid interface in an electric field, wave motion, and surface instability  

NASA Astrophysics Data System (ADS)

A variation in the reflection coefficient of an interface of two liquids (water and magnetic liquid) in the presence of an electric field is experimentally studied. An increase in the reflection coefficient of the interface is demonstrated. A surface instability of the water-magnetic liquid interface, the wave motion at the interface, and wave interference are observed.

Chekanov, V. V.; Kandaurova, N. V.; Chekanov, V. S.

2014-09-01