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1

Water: The Strangest Liquid  

Microsoft Academic Search

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,

2009-01-01

2

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

3

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

NASA Astrophysics Data System (ADS)

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

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

2009-10-01

4

Impulse breakdown of liquid water  

Microsoft Academic Search

Currently, studies of microsecond and sub-microsecond electrical breakdown in liquid water and water solutions are experiencing their renaissance period due to the development of advanced pulsed power systems and emerging technologies for environmental applications and plasma medicine. The present paper is focused on an investigation of polarity effects in sub-microsecond discharges in water. Distilled water, tap water and water based

I. V. Timoshkin; M. J. Given; M. P. Wilson; R. A. Fouracre; S. J. MacGregor

2010-01-01

5

Dissolving Different Liquids in Water  

NSDL National Science Digital Library

In this activity, students 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, students can conclude that while some liquids may dissolve in water, different liquids dissolve in water to different extents. There is a downloadable activity sheet that will be very helpful to educators, and will help students stay on track. An assessment sheet is also available on the activity page to keep track of students progress. There is also a step by step guide as to how to perform the experiment, and how to introduce it t the students.

Kessler, James; Galvan, Patti

2010-01-01

6

Measuring Snow's Liquid Water Content.  

National Technical Information Service (NTIS)

This citation summarizes a one-page announcement of technology available for utilization. The liquid, or unfrozen, water in a snowpack has a major effect on the absorption, reflection and transmission by the snow of electromagnetic waves. Often the effect...

1984-01-01

7

Quinaldine: Accessing two crystalline polymorphs via the supercooled liquid  

NASA Astrophysics Data System (ADS)

Quinaldine (2-methyl quinoline) is a liquid at room temperature, which can be supercooled to reach finally the glassy state. By heating the glass above the glass transition temperature Tg = 180 K the sample performs two subsequent transitions into, likewise, dielectrically active phases. Thus, the reorientational relaxations of these phases as well as the kinetics of the phase transitions can be tracked in a highly resolved way by dielectric spectroscopy. X-ray diffraction analysis clearly shows two structurally different crystalline phases in addition to the supercooled liquid. Calorimetric measurements support the notion of first order phase transitions, occurring irreversibly in the supercooled regime, and suggest that the intermediate crystalline phase is metastable, too. Analyzing the quite distinct dielectric relaxation strengths, we discuss the possible nature of the two crystalline phases. Additionally, a very similar behavior to quinaldine is observed for 3-methyl quinoline, indicating a broad field of polymorphism among the quinoline derivatives.

Kahlau, Robert; Gnutzmann, Tanja; Emmerling, Franziska; Rademann, Klaus; Rössler, Ernst A.

2012-08-01

8

Density Fluctuations in Liquid Water  

NASA Astrophysics Data System (ADS)

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

English, Niall J.; Tse, John S.

2011-01-01

9

Depolarization of water in protic ionic liquids.  

PubMed

A mixture of the protic ionic liquid mono-methylammonium nitrate with 1.6 wt% water was investigated from Car-Parrinello molecular dynamics simulations. In contrast to imidazolium-based ionic liquids, the cation possesses strong directional hydrogen bonds to water and all hydrogen bonds in the mixture have a comparable strength. This results in a good incorporation of water into the hydrogen bond network of mono-methylammonium nitrate and a tetrahedral hydrogen bond coordination of water. Hence, one might expect a larger dipole moment of water in the investigated mixture compared to neat water due to the good hydrogen bond network incorporation and the charged vicinity of water in the protic ionic liquid. However, the opposite is observed pointing to strong electrostatic screening in protic ionic liquids. Additionally, the influence of water on the properties of the protic ionic liquid is discussed. PMID:21769354

Zahn, Stefan; Wendler, Katharina; Delle Site, Luigi; Kirchner, Barbara

2011-07-18

10

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

NASA Astrophysics Data System (ADS)

We will introduce some of the 63 anomalies of the most complex of liquids, water. We will demonstrate some recent progress in understanding these anomalies by combining information provided by recent experiments and simulations on water in bulk, nanoconfined, and biological environments. We will interpret evidence from recent experiments designed to test the hypothesis that liquid water may display ``polymorphism'' in that it can exist in two different phases---and discuss recent work on water's transport anomalies [1] as well as the unusual behavior of water in biological environments [2]. Finally, we will discuss how the general concept of liquid polymorphism [3] is proving useful in understanding anomalies in other liquids, such as silicon, silica, and carbon, as well as metallic glasses, which have in common that they are characterized by two characteristic length scales in their interactions. This work was supported by NSF Chemistry Division, and carried out in collaboration with a number of colleagues, chief among whom are C. A. Angell, M. C. Barbosa, M. C. Bellissent, L. Bosio, F. Bruni, S. V. Buldyrev, M. Canpolat, S. -H. Chen, P. G. Debenedetti, U. Essmann,G. Franzese, A. Geiger, N. Giovambattista, S. Han, P. Kumar, E. La Nave,G. Malescio, F. Mallamace, M. G. Mazza, O. Mishima, P. Netz, P. H. Poole, P. J. Rossky, R. Sadr,S. Sastry, A. Scala, F. Sciortino, A. Skibinsky, F. W. Starr, K. C. Stokely J. Teixeira, L. Xu, and Z. Yan.[4pt] [1] L. Xu, F. Mallamace, Z. Yan, F. W. Starr, S. V. Buldyrev, and H. E. Stanley, ``Appearance of a Fractional Stokes-Einstein Relation in Water and a Structural Interpretation of Its Onset,'' Nature Physics 5, 565--569 (2009). [0pt] [2] P. Kumar, Z. Yan, L. Xu, M. G. Mazza, S. V. Buldyrev, S. -H. Chen. S. Sastry, and H. E. Stanley, ``Glass Transition in Biomolecules and the Liquid-Liquid Critical Point of Water,'' Phys. Rev. Lett. 97, 177802 (2006). [0pt] [3] H. E. Stanley, ed. , Liquid Polymorphism [Advances in Chemical Physics], series edited by S. A. Rice (Wiley, New York, 2010).

Stanley, H. Eugene

2010-03-01

11

Role of water in Protein Aggregation and Amyloid Polymorphism  

PubMed Central

Conspectus The link between oligomers and amyloid fibrils and a variety of neurodegenerative diseases raises the need to decipher the principles governing protein aggregation. Mechanisms of in vivo amyloid formation involve a number of coconspirators and complex interactions with membranes. Nevertheless, it is believed that understanding the biophysical basis of in vitro amyloid formation in well-defined systems is important in discovering ligands that preferentially bind to regions that harbor amyloidogenic tendencies. Determination of structures of fibrils of a variety of peptides has set the stage for probing the dynamics of oligomer formation and amyloid growth using computer simulations. Most experimental and simulation studies have been interpreted largely from the perspective of proteins without much consideration of the role of solvent in enabling or inhibiting oligomer formation and assembly to protofilaments and amyloid fibrils. Here, we provide a perspective on how interactions with water affect folding landscapes of A? monomers, oligomer formation in A?16–22 fragment, protofilament formation in a peptide from yeast prion Sup35. Explicit molecular dynamics simulations of these systems illustrate how water controls the self-assembly of higher order structures and provide a structural basis for understanding the kinetics of oligomer and fibril growth. Simulations show that monomers of A?-peptides sample a number of compact conformations. Population of aggregation-prone structures (N*) with salt-bridge, which bear a striking similarity to the peptide structure in the fibril, requires overcoming a high desolvation barrier. In general, sequences for which N* structures are not significantly populated are unlikely to aggregate. Generically oligomers and fibrils form in two steps. In the first stage water is expelled from the region between peptides rich in hydrophobic residues (for example A?16–22) resulting in the disordered oligomers. In the second stage, the peptides align along a preferred axis to form ordered structures with anti-parallel ?-strand arrangement. The rate limiting step in the ordered assembly is the rearrangement of the peptides within a confining volume. The mechanism of protofilament formation in a polar peptide fragment from the yeast prion in which the two sheets are packed against each other creating a dry interface illustrates that water dramatically slows down self-assembly. As the sheets approach each other two perfectly ordered one-dimensional water wires, which are stabilized by hydrogen bonds to the amide groups of the polar side chains, results in the formation of long-lived metastable structures. Release of the trapped water from the pore creates a helically-twisted protofilament with a dry interface. Similarly, the driving force for addition of a solvated monomer to a preformed fibril is the release of water whose entropy gain and favorable inter peptide hydrogen bond formation compensates for loss in entropy of the peptides. We suggest that the two-step mechanism, a model also used in protein crystallization, must hold good for higher order amyloid structure formation. In the first step a liquid droplet rich in proteins containing N* structures form. Conformational rearrangement of the peptides leading to an ordered state occurs within the droplet by incorporation of monomers or collision with other droplets and ultimately results in ?-amyloid formation. Because there is an ensemble of distinct N* structures with varying water content there must be a number of distinct water-laden polymorphic structures. Evidence for this proposal is presented. Water plays multifarious roles, which in the case of predominantly hydrophobic sequences, accelerates fibril formation. In contrast, water-stabilized metastable intermediates dramatically slow down fibril growth rates in hydrophilic sequences.

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

2011-01-01

12

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

13

Vitrification of pure liquid water by high pressure jet freezing  

Microsoft Academic Search

The vitrification of pure liquid water by projecting a thin jet of liquid water at high speed into a liquid cryomedium is reported. The influence of the experimental parameters on the cooling rate and the devitrification of the jet-frozen vitrified material have been investigated. A structural difference between vitrified liquid water and amorphous solid water prepared from the vapour phase

Erwin Mayer; Peter Brüggeller

1982-01-01

14

Liquid water oceans in ice giants  

NASA Astrophysics Data System (ADS)

Aptly named, ice giants such as Uranus and Neptune contain significant amounts of water. While this water cannot be present near the cloud tops, it must be abundant in the deep interior. We investigate the likelihood of a liquid water ocean existing in the hydrogen-rich region between the cloud tops and deep interior. Starting from an assumed temperature at a given upper tropospheric pressure (the photosphere), we follow a moist adiabat downward. The mixing ratio of water to hydrogen in the gas phase is small in the photosphere and increases with depth. The mixing ratio in the condensed phase is near unity in the photosphere and decreases with depth; this gives two possible outcomes. If at some pressure level the mixing ratio of water in the gas phase is equal to that in the deep interior, then that level is the cloud base. The gas below the cloud base has constant mixing ratio. Alternately, if the mixing ratio of water in the condensed phase reaches that in the deep interior, then the surface of a liquid ocean will occur. Below this ocean surface, the mixing ratio of water will be constant. A cloud base occurs when the photospheric temperature is high. For a family of ice giants with different photospheric temperatures, the cooler ice giants will have warmer cloud bases. For an ice giant with a cool enough photospheric temperature, the cloud base will exist at the critical temperature. For still cooler ice giants, ocean surfaces will result. A high mixing ratio of water in the deep interior favors a liquid ocean. We find that Neptune is both too warm (photospheric temperature too high) and too dry (mixing ratio of water in the deep interior too low) for liquid oceans to exist at present. To have a liquid ocean, Neptune's deep interior water to gas ratio would have to be higher than current models allow, and the density at 19 kbar would have to be ?0.8 g/cm. Such a high density is inconsistent with gravitational data obtained during the Voyager flyby. In our model, Neptune's water cloud base occurs around 660 K and 11 kbar, and the density there is consistent with Voyager gravitational data. 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.

Wiktorowicz, Sloane J.; Ingersoll, Andrew P.

2007-02-01

15

Remote sensing of liquid water target operations  

SciTech Connect

One of the key considerations in the design of automated liquid water target systems for reliable {sup 18}F{sup {minus}} production is the inclusion of adequate sensing devices for remote feedback of individual process operation status. The process operations needed to generate, extract and deliver {sup 18}F{sup {minus}} to the Hot Lab for subsequent chemistry are not very complex. These involve configuring target valves for access during loading of enriched water, filling the target with water, reconfiguring the target valves so that it is sealed during irradiation, and finally emptying the target contents after irradiation. At the lowest level of remote sensing of these operations is the act of determining whether target valves are actually in their correct configuration for a specific step. Sensing the filling or emptying status of the target is perhaps the most crucial feedback for reliable target performance. Sensing the presence, or absence, of liquid water can be accomplished by measuring some physical property of the substance in that phase. The use of electrical conductivity meters is one method we have discussed in the past in relation to the remote sensing of metal cations to determine the presence of water. Likewise, refractive index is another property of water that can be harnessed for sensing the liquid`s presence. The performance of an optical sensor in the BNL JSW beamline for routine production of {sup 18}F{sup {minus}} is discussed.

Ferrieri, R.A.; Alexoff, D.L.; Schlyer, D.J.

1993-12-31

16

Liquid Polyamorphism and the Anomalous Behavior of Water  

Microsoft Academic Search

We present evidence from experiments and computer simulations supporting the hypothesis that ?dex{polyamorphism}water displays\\u000a polyamorphism, i.e., water separates into two distinct liquid phases. This concept of a new ?dex{liquid-liquid phase transition}liquid–liquid\\u000a phase transition is finding potential application to other liquids as well as water, such as silicon and silica. Here we review\\u000a the relation between changes in dynamic and thermodynamic

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

2009-01-01

17

Planetary protection and liquid water on Mars  

NASA Astrophysics Data System (ADS)

An important component of the Planetary Protection Program is the assessment of the potential habitability of extraterrestrial locations for Earth microbes inadvertently carried there. It is imperative that the most accurate assessment of extraterrestrial habitability be made. This is particularly urgent for the surface of Mars because many missions are planned to explore various environments on Mars in the near future. Upcoming missions to Mars will be radio-thermal generating system-powered. These heat sources will modify the microclimate and its habitability for extant life, especially in the event that such a platform crashes on the martian surface. This is particularly urgent for the surface of Mars because many missions are planned to explore various environments on Mars in the near future. Because the goal of many of these missions is directly tied to the search for evidence of life, it is not surprising that the locations of interest are those most likely to provide a habitat for life. This change could hinder or aid extant life or provide an abode for Earth organisms to survive under these modified martian conditions. The key requirement for habitability is the presence of liquid water. One source of water for these organisms could be from snowmelt from water-rich snow deposits. These snowmelts could provide episodic liquid water for life in the past or the present. It is interesting therefore to consider the effect of an RTG if placed on surface ice in the polar regions of Mars. For liquid water to be present on Mars three requirements must be met: 1) the pressure must be above the boiling point of water, the lowest boiling point possible is the triple point (610 Pa). 2) The temperature of the water must be above the freezing point but below the boiling point. 3) There must be a source of water. The study reported here is composed of three related tasks: 1) Assess the locations on Mars where natural conditions sustain an environment in which liquid water could be stable. 2) Identify locations on Mars where ground ice or seasonal ice deposits are present in locations where conditions allow for liquid water stability. 3) Identify locations where ground ice is present and where an artificial heat source from a spacecraft or lander would generate liquid water. The first task used MOLA high resolution data and the Viking Lander surface pressure measurements to compute the expected surface pressure through the martian year. This result was then coupled with direct measurements of temperature from Mars Global Surveyor TES to determine possible sites for liquid water. We found considerable regions on Mars in which liquid water - if present - would be stable for short time periods. These regions were then combined with observed ground ice locations that could be sources of liquid water (task 2). Modifications to the microclimate temperature regime due to an RTG on the surface were then considered in task 3 based on heat transfer modeling results to determine how much and where the stability regions were affected.

Lobitz, B. M.; McKay, C. P.

18

Radiation Affected Liquid Fuel Burning on Water  

Microsoft Academic Search

A model for the radiation affected liquid fuel burning on water is developed which improves substantially on an existing model by including the turbulent fire plume and the explicit effects (hotness and thickness) of fire radiation. In achieving these objectives, the experimental literature on flame height and velocity is utilized. The fire plume above the slick is divided into three

Mohammad A. Alramadhan

1989-01-01

19

Radiation Affected Liquid Fuel Burning on Water  

Microsoft Academic Search

A model for the radiation affected liquid fuel burning on water is developed which improves substantially on an existing model by including the turbulent fire plume and the explicit effects (hotness and optical thickness) of fire radiation. In achieving these objectives, the experimental literature on flame height and velocity is utilized. The fire plume above the slick is divided into

M. A. ALRAMADHAN; V. S. ARPACI; A. SELAMET

1990-01-01

20

IXODID TICKS AVOID CONTACT WITH LIQUID WATER  

Microsoft Academic Search

Larvae of the cattle tick Boophilus microplus and all life stages of the European sheep tick Ixodes ricinus avoid walking on a wet membrane surface surrounding a dry patch. Of 170 reactions made at a border with liquid water by 22 B. microplus larvae, 40 % consisted of immediate turns to the opposite side to bring all the legs back

T. KRÖBER; P. M. GUERIN

21

Liquid water and active resurfacing on Europa  

Microsoft Academic Search

Arguments for recent resurfacing of Europa by H2O from a liquid layer are presented, based on new interpretations of recent spacecraft and earth-based observations and revised theoretical calculations. The heat flow in the core and shell due to tidal forces is discussed, and considerations of viscosity and convection in the interior are found to imply water retention in the outer

S. W. Squyres; R. T. Reynolds; P. M. Cassen

1983-01-01

22

Liquid-liquid-solid equilibria for the ternary systems butanols + water + sodium chloride or + potassium chloride  

SciTech Connect

Liquid-liquid-solid equilibria for the ternary systems water + sodium chloride + 2-butanol, water + sodium chloride + 2-methyl-1-propanol, water + sodium chloride + 2-methyl-2-propanol, water + potassium chloride + 1-butanol, water + potassium chloride + 2-butanol, water + potassium chloride + 2-methyl-1-propanol, and water + potassium chloride + 2-methyl-2-propanol have been measured at 25 C.

Gomis, V.; Ruiz, F.; Asensi, J.C.; Saquete, M.D. [Univ. de Alicante (Spain). Dept. de Ingenieria Quimica

1996-03-01

23

Ionic liquids are compatible with on-water catalysis.  

PubMed

A major limitation of on-water catalysis has been the need for liquid reactants to enable emulsification. We demonstrate that ionic liquids are compatible with on-water catalysis, enabling on-water catalysed reactions for otherwise unreactive solid-solid systems. The unique solvation properties of ionic liquids dramatically expands the scope of on-water catalysis. PMID:23929275

Beare, Kaitlin D; Yuen, Alexander K L; Masters, Anthony F; Maschmeyer, Thomas; McErlean, Christopher S P

2013-08-22

24

Solvent-dependent stabilization of metastable monolayer polymorphs at the liquid-solid interface.  

PubMed

Self-assembly of 1,3,5-tris(4'-biphenyl-4"-carbonitrile)benzene monolayers was studied at the liquid-solid interface by scanning tunneling microscopy. Application of different fatty acid homologues as solvents revealed a solvent-induced polymorphism. Yet, tempering triggered irreversible phase transitions of the initially self-assembled monolayers, thereby indicating their metastability. Interestingly, in either case, the same thermodynamically more stable and more densely packed monolayer polymorph was obtained after thermal treatment, irrespective of the initial structure. Again, the same densely packed structure was obtained in complementary solvent-free experiments conducted under ultrahigh vacuum conditions. Thus, self-assembly of metastable polymorphs at room temperature is explained by adsorption of partially solvated species under kinetic control. The irreversible phase transitions are induced by thermal desolvation, that is, desorption of coadsorbed solvent molecules. PMID:23875955

Sirtl, Thomas; Song, Wentao; Eder, Georg; Neogi, Subhadip; Schmittel, Michael; Heckl, Wolfgang M; Lackinger, Markus

2013-07-29

25

Anomalies of water and simple liquids  

NASA Astrophysics Data System (ADS)

This thesis applies statistical physics approaches and computer simulations to investigate quantitatively the relationship between the structure and the dynamic and thermodynamic anomalies observed in water and some other simple liquids. In Chapter 1, we give a general introduction to the properties of water. In Chapter 2 we address the question of whether spherically-symmetric potentials are also able to reproduce the structural anomalies found in systems with local tetrahedral order. We find that water-like structural order anomalies exist for the two-scale "ramp potential". Our findings suggest that the water-like relationship between structural order and anomalies is related to the presence of two different length scales in the potential. In Chapter 3, we use the ratio of characteristic length scales of the two-scale ramp potential as a control parameter to investigate the evolution of dynamic, thermodynamic and structural anomalies. In this manner we show that the family of tunable spherically-symmetric potentials so generated evolves continuously between water-like and hard sphere behavior. These findings suggest that strong orientational interactions in the first shell of water are not necessary for a liquid to show thermodynamic, dynamic and structural anomalies, and highlight the importance of the second shell of water. In Chapter 4, we investigate how much orientation-dependent first-shell interaction and the second-shell environment each contribute to water's anomalies. We show that the changes in the second shell of water are the structural bases for the anomalies. In Chapter 5, we study the quantitative connection between our idealized ramp potential and water's pair potential, as well as the relation between the regions of anomalies in their respective phase diagrams. Finally in Chapter 6 we show that the "two-body excess entropy" is a useful quantity for predicting the regions of thermodynamic, dynamic and structural anomalies of water.

Yan, Zhenyu

26

Liquid Hot Water Pretreatment of Cellulosic Biomass  

NASA Astrophysics Data System (ADS)

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

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

27

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.

28

Long-term evolution of transient liquid water on Mars  

Microsoft Academic Search

Liquid water is not currently stable on the surface of Mars; however, transient liquid water (ice melt) may occur if the surface temperature is between the melting and boiling points. Such conditions are met on Mars with current surface pressures and obliquity due to the large diurnal range of surface temperatures. This yields the potential for transient, nonequilibrium liquid water.

Mark I. Richardson; Michael A. Mischna

2005-01-01

29

Diagnostic tools for liquid water in PEM fuel cells  

Microsoft Academic Search

This paper describes a novel diagnostic test method that provides insight into the distribution of liquid water in a fuel cell under operation. The amount and distribution of liquid water in a fuel cell is measured indirectly through the measurement of certain physico-chemical properties which are functions of the liquid water content.The MEA resistance and electrode diffusivity (MRED) method allows

Jürgen Stumper; Michael Löhr; Stephen Hamada

2005-01-01

30

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

PubMed

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

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

2009-12-01

31

Displacement of nonwetting liquids from unsaturated sands by water infiltration  

Microsoft Academic Search

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

Troy M. Boley; Thomas J. Overcamp

1998-01-01

32

Role of water in protein aggregation and amyloid polymorphism.  

PubMed

A variety of neurodegenerative diseases are associated with amyloid plaques, which begin as soluble protein oligomers but develop into amyloid fibrils. Our incomplete understanding of this process underscores the need to decipher the principles governing protein aggregation. Mechanisms of in vivo amyloid formation involve a number of coconspirators and complex interactions with membranes. Nevertheless, understanding the biophysical basis of simpler in vitro amyloid formation is considered important for discovering ligands that preferentially bind regions harboring amyloidogenic tendencies. The determination of the fibril structure of many peptides has set the stage for probing the dynamics of oligomer formation and amyloid growth through computer simulations. Most experimental and simulation studies, however, have been interpreted largely from the perspective of proteins: the role of solvent has been relatively overlooked in oligomer formation and assembly to protofilaments and amyloid fibrils. In this Account, we provide a perspective on how interactions with water affect folding landscapes of amyloid beta (A?) monomers, oligomer formation in the A?16-22 fragment, and protofilament formation in a peptide from yeast prion Sup35. Explicit molecular dynamics simulations illustrate how water controls the self-assembly of higher order structures, providing a structural basis for understanding the kinetics of oligomer and fibril growth. Simulations show that monomers of A? peptides sample a number of compact conformations. The formation of aggregation-prone structures (N*) with a salt bridge, strikingly similar to the structure in the fibril, requires overcoming a high desolvation barrier. In general, sequences for which N* structures are not significantly populated are unlikely to aggregate. Oligomers and fibrils generally form in two steps. First, water is expelled from the region between peptides rich in hydrophobic residues (for example, A?16-22), resulting in disordered oligomers. Then the peptides align along a preferred axis to form ordered structures with anti-parallel ?-strand arrangement. The rate-limiting step in the ordered assembly is the rearrangement of the peptides within a confining volume. The mechanism of protofilament formation in a polar peptide fragment from the yeast prion, in which the two sheets are packed against each other and create a dry interface, illustrates that water dramatically slows self-assembly. As the sheets approach each other, two perfectly ordered one-dimensional water wires form. They are stabilized by hydrogen bonds to the amide groups of the polar side chains, resulting in the formation of long-lived metastable structures. Release of trapped water from the pore creates a helically twisted protofilament with a dry interface. Similarly, the driving force for addition of a solvated monomer to a preformed fibril is water release; the entropy gain and favorable interpeptide hydrogen bond formation compensate for entropy loss in the peptides. We conclude by offering evidence that a two-step model, similar to that postulated for protein crystallization, must also hold for higher order amyloid structure formation starting from N*. Distinct water-laden polymorphic structures result from multiple N* structures. Water plays multifarious roles in all of these protein aggregations. In predominantly hydrophobic sequences, water accelerates fibril formation. In contrast, water-stabilized metastable intermediates dramatically slow fibril growth rates in hydrophilic sequences. PMID:21761818

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

2011-07-15

33

Interfacial water - the only liquid water in the upper martian subsurface  

Microsoft Academic Search

It is shown, after introducing the physics of liquid water on and in the upper surface of Mars, that interfacial water is the only liquid water on present days Mars. Water ice on a mineral surface is not generally stable. A microscopic liquid layer of \\

Diedrich Möhlmann

2008-01-01

34

Streamers in water and other dielectric liquids  

NASA Astrophysics Data System (ADS)

Experimental results on the inception and propagation of streamers in water generated under the application of high electric fields are reviewed. Characteristic parameters, such as breakdown voltage, polarity of the applied voltage, propagation velocities and other phenomenological features, are compared with similar phenomena in other dielectric liquids and in gases. Consequently, parameters that are expected to influence the development of streamers in water are discussed with respect to the analogous well-established models and theories for the related mechanisms in gases. Most of the data support the notion that an initial low-density nucleation site or gas-filled bubble assists the initiation of a streamer. Details of this theory are laid out explaining the observed differences in the breakdown originating from the anode versus the cathode locations. The mechanisms can also be applied to streamer propagation, although some observations cannot be satisfactorily explained.

Kolb, J. F.; Joshi, R. P.; Xiao, S.; Schoenbach, K. H.

2008-12-01

35

PERMEABILITY OF SOILS TO FOUR ORGANIC LIQUIDS AND WATER  

EPA Science Inventory

Saturated hydraulic conductivities and intrinsic permeabilities were evaluated for eight contrasting soils with four organic liquids and water. The organic liquids were kerosene, ethylene glycol, isopropyl alcohol and xylene. Intrinsic permeability for any given soil varied inver...

36

Phase and dielectric behaviors of a polymorphic liquid crystal doped with graphene nanoplatelets  

NASA Astrophysics Data System (ADS)

We report on the phase behavior and dielectric properties of the liquid crystal (LC) 4'-n-octyloxy-4-cyanobiphenyl dispersed with graphene nanoplatelets (GNPs). The temperature-dependent dielectric permittivity at 104 Hz and its derivative with respect to the temperature reveal that the incorporation of GNPs in a LC cell leads to the modification of crystalline polymorphism and shift in phase transition temperature owing to the enhanced positional and orientational order. Additionally, the dielectric data between 1 and 103 Hz show that the dopant reduces the ionic concentration and alters the diffusivity in the LC mesophases.

Wu, Po-Chang; Lee, Wei

2013-04-01

37

Liquid-liquid transition in ST2 water  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

38

Liquid-liquid transition in ST2 water.  

PubMed

We use the weighted histogram analysis method [S. Kumar, D. Bouzida, R. H. Swendsen, P. A. Kollman, and J. M. Rosenberg, J. Comput. Chem. 13, 1011 (1992)] to calculate the free energy surface of the ST2 model of water as a function of density and bond-orientational order. We perform our calculations at deeply supercooled conditions (T = 228.6 K, P = 2.2 kbar; T = 235 K, P = 2.2 kbar) and focus our attention on the region of bond-orientational order that is relevant to disordered phases. We find a first-order transition between a low-density liquid (LDL, ? ? 0.9 g/cc) and a high-density liquid (HDL, ? ? 1.15 g/cc), confirming our earlier sampling of the free energy surface of this model as a function of density [Y. Liu, A. Z. Panagiotopoulos, and P. G. Debenedetti, J. Chem. Phys. 131, 104508 (2009)]. We demonstrate the disappearance of the LDL basin at high pressure and of the HDL basin at low pressure, in agreement with independent simulations of the system's equation of state. Consistency between directly computed and reweighted free energies, as well as between free energy surfaces computed using different thermodynamic starting conditions, confirms proper equilibrium sampling. Diffusion and structural relaxation calculations demonstrate that equilibration of the LDL phase, which exhibits slow dynamics, is attained in the course of the simulations. Repeated flipping between the LDL and HDL phases in the course of long molecular dynamics runs provides further evidence of a phase transition. We use the Ewald summation with vacuum boundary conditions to calculate long-ranged Coulombic interactions and show that conducting boundary conditions lead to unphysical behavior at low temperatures. PMID:23231249

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

2012-12-01

39

Determination of four heterocyclic insecticides by ionic liquid dispersive liquid-liquid microextraction in water samples.  

PubMed

A novel microextraction method termed ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) combining high-performance liquid chromatography with diode array detection (HPLC-DAD) was developed for the determination of insecticides in water samples. Four heterocyclic insecticides (fipronil, chlorfenapyr, buprofezin, and hexythiazox) were selected as the model compounds for validating this new method. This technique combines extraction and concentration of the analytes into one step, and the ionic liquid was used instead of a volatile organic solvent as the extraction solvent. Several important parameters influencing the IL-DLLME extraction efficiency such as the volume of extraction solvent, the type and volume of disperser solvent, extraction time, centrifugation time, salt effect as well as acid addition were investigated. Under the optimized conditions, good enrichment factors (209-276) and accepted recoveries (79-110%) were obtained for the extraction of the target analytes in water samples. The calibration curves were linear with correlation coefficient ranged from 0.9947 to 0.9973 in the concentration level of 2-100 microg/L, and the relative standard deviations (RSDs, n=5) were 4.5-10.7%. The limits of detection for the four insecticides were 0.53-1.28 microg/L at a signal-to-noise ratio (S/N) of 3. PMID:19118833

Liu, Yu; Zhao, Ercheng; Zhu, Wentao; Gao, Haixiang; Zhou, Zhiqiang

2008-12-03

40

Cryovolcanism and the Recent Flow of Liquid Water on Mars  

Microsoft Academic Search

The surface of Mars is too cold and dry to permit stable liquid water, yet fresh, apparently water-carved gullies and seepage features have been identified in high-resolution imaging of canyon and crater walls by the Mars Global Surveyor spacecraft. Here, a model of nonequilibrium hydrological activity and liquid water cryovolcanism explains the paradoxical appearance and observed properties of these landforms:

Eric J. Gaidos

2001-01-01

41

Effect of liquid fat on melting point and polymorphic behavior of cocoa butter and a cocoa butter fraction  

Microsoft Academic Search

The polymorphic behavior of cocoa butter and a high-melting fraction of cocoa butter (CBF) was investigated by differential\\u000a scanning calorimetry. The effect of liquid fat on melting point and polymorphic behavior was established for six mixtures:\\u000a 83.5% cocoa butter and 16.5% of a low-melting fraction of cocoa butter (CBF-LM), 90% cocoa butter and 10% olive oil, and four\\u000a mixtures of

N. V. Lovegren; M. S. Gray; R. O. Feuge

1976-01-01

42

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

43

Combustion of nano-aluminum and liquid water  

Microsoft Academic Search

An experimental investigation on the combustion behavior of nano-aluminum (nAl) and liquid water has been conducted. In particular, linear and mass-burning rates of quasi-homogeneous mixtures of nAl and liquid water as a function of pressure, mixture composition, particle size, and oxide layer thickness were measured. This study is the first reported self-deflagration on nAl and liquid water without the use

G. A. Risha; S. F. Son; R. A. Yetter; V. Yang; B. C. Tappan

2007-01-01

44

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

45

Liquid-liquid transition without macroscopic phase separation in a water-glycerol mixture.  

PubMed

The existence of more than two liquid states in a single-component substance and the ensuing liquid-liquid transitions (LLTs) has attracted considerable attention because of its counterintuitive nature and its importance in the fundamental understanding of the liquid state. Here we report direct experimental evidence for a genuine (isocompositional) LLT without macroscopic phase separation in an aqueous solution of glycerol. We show that liquid I transforms into liquid II by way of two types of kinetics: nucleation and growth, and spinodal decomposition. Although liquid II is metastable against crystallization, we could access both its static and dynamical properties experimentally. We find that liquids I and II differ in density, refractive index, structure, hydrogen bonding state, glass transition temperature and fragility, and that the transition between the two liquids is mainly driven by the local structuring of water rather than of glycerol, suggesting a link to a plausible LLT in pure water. PMID:22426459

Murata, Ken-ichiro; Tanaka, Hajime

2012-03-18

46

Liquid-liquid transition without macroscopic phase separation in a water-glycerol mixture  

NASA Astrophysics Data System (ADS)

The existence of more than two liquid states in a single-component substance and the ensuing liquid-liquid transitions (LLTs) has attracted considerable attention because of its counterintuitive nature and its importance in the fundamental understanding of the liquid state. Here we report direct experimental evidence for a genuine (isocompositional) LLT without macroscopic phase separation in an aqueous solution of glycerol. We show that liquid I transforms into liquid II by way of two types of kinetics: nucleation and growth, and spinodal decomposition. Although liquid II is metastable against crystallization, we could access both its static and dynamical properties experimentally. We find that liquids I and II differ in density, refractive index, structure, hydrogen bonding state, glass transition temperature and fragility, and that the transition between the two liquids is mainly driven by the local structuring of water rather than of glycerol, suggesting a link to a plausible LLT inpure water.

Murata, Ken-Ichiro; Tanaka, Hajime

2012-05-01

47

Space Station Water Processor Mostly Liquid Separator (MLS).  

National Technical Information Service (NTIS)

This report presents the results of the development testing conducted under this contract to the Space Station Water Processor (WP) Mostly Liquid Separator (MLS). The MLS units built and modified during this testing demonstrated acceptable air/water separ...

A. Lanzarone

1995-01-01

48

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

PubMed

Systems of particles with interactions given by the Jagla core-softened pair potential are known to exhibit water-like thermodynamic anomalies and a liquid-liquid phase transition. The drawback of the Jagla potential is that it is characterized by discontinuous forces acting between particles and thus is not suitable for standard molecular dynamics (MD) simulations. Here we introduce a smooth version of the Jagla potential based on two Fermi distributions and study the properties of a system of particles interacting via this new "Fermi-Jagla" pair potential by using standard MD simulations. We find that the liquid based on the Fermi-Jagla potential retains most of the properties of the liquid based on the original Jagla potential. Namely, it exhibits the following water-like anomalies: (i) decrease of density, (ii) increase of compressibility, ?(T)(T,P), and (iii) increase of isobaric specific heat, C(P)(T,P), upon isobaric cooling, and (iv) increase of diffusivity upon isothermal compression. The Fermi-Jagla potential also exhibits (i') density minima, (ii') compressibility minima, (iii') isobaric specific heat minima upon isobaric cooling, and (iv') diffusivity minima upon isothermal compression. As in the Jagla model case, we find a liquid-liquid phase transition (LLPT) and a liquid-liquid critical point in the equilibrium liquid. Contrary to the case of the original Jagla model liquid, the LLPT line for the Fermi-Jagla potential has a negative slope in the P-T plane that extends well above the crystallization temperature. This feature makes the Fermi-Jagla potential a better candidate to reproduce the behavior of tetrahedral liquids including water, for which the LLPT line observed in simulations has also negative slope. In the glass state, the Fermi-Jagla pair potential results in reversible polyamorphism between low- and high-density amorphous solids (LDA and HDA, respectively). We also find that HDA results from pressure-induced amorphization of the model's low pressure crystal, as observed in water and other materials. The Fermi-Jagla pair potential, being a smooth function of the interparticle separation, can be easily implemented in standard MD simulation codes. Moreover, since spontaneous crystallization for the Fermi-Jagla potential can be avoided by fast cooling, it can be used to study the phenomenology of glasses. PMID:21992558

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

2011-10-12

49

Liquid–liquid equilibrium data of water with neohexane, methylcyclohexane, tert-butyl methyl ether, n-heptane and vapor–liquid–liquid equilibrium with methane  

Microsoft Academic Search

Liquid–liquid equilibrium (LLE) data for non-aqueous liquid (neohexane [NH], tert-butyl methyl ether [TBME], methylcyclohexane [MCH], or n-heptane [nC7]) and water have been measured under atmospheric pressure at 275.5, 283.15, and 298.15K. It was found that TBME is the most water soluble followed by NH, MCH, and nC7. As the temperature increased, the solubility of the non-aqueous liquids (NALs) in water

R. Susilo; J. D. Lee; P. Englezos

2005-01-01

50

Liquid polyamorphism: Possible relation to the anomalous behaviour of water  

Microsoft Academic Search

.  We present evidence from experiments and computer\\u000a simulations supporting the hypothesis that water displays\\u000a polyamorphism, i.e., water separates into two distinct liquid\\u000a phases. This concept of a new liquid-liquid phase transition is\\u000a finding application to other liquids as well as water, such as\\u000a silicon and silica. Specifically, we investigate, the relation\\u000a between changes in dynamic and thermodynamic anomalies arising from

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

2008-01-01

51

Thermodynamic Properties of Liquid Water to One Kilobar.  

National Technical Information Service (NTIS)

Recent accurate experimental P-v-t data for pure liquid water, in the range 0 to 1000 bars and 0 to 150C, are combined with other data at P = 1 atmosphere and on the saturation line, to get the thermodynamic functions for liquid water throughout this rang...

W. A. Walker

1967-01-01

52

Searching for Liquid Water in Europa by Using Surface Observatories  

Microsoft Academic Search

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

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

2002-01-01

53

Cloud Liquid Water and Ice Content Retrieval by Multiwavelength Radar  

Microsoft Academic Search

Cloud liquid water and ice content retrieval in precipitating clouds by the differential attenuation method using a dual-wavelength radar, as a function of the wavelength pair, is first discussed. In the presence of non- Rayleigh scatterers, drizzle, or large ice crystals, an ambiguity appears between attenuation and non-Rayleigh scattering. The liquid water estimate is thus biased regardless of which pair

Nicolas Gaussiat; Henri Sauvageot; Anthony J. Illingworth

2003-01-01

54

The influence of polymorphic form on oxygen and water vapor transmission through lipid films  

Microsoft Academic Search

Fully-hydrogenated soybean and rapeseed oil was blended 2:1, layered on a filter paper support, adjusted to the desired polymorphic\\u000a form and tested for resistance to transmission to oxygen and water vapor. Resistance to oxygen transport decreased upon conversion\\u000a from ? to the ?? form and then increased substantially upon conversion to the ? polymorph. This was attributed to the greater

J. J. Kester; O. Fennema

1989-01-01

55

Ultrafast vibrational dynamics of liquid water  

Microsoft Academic Search

Multidimensional IR spectroscopy has the power to demystify molecular dynamics in the liquid phase. It allows a glimpse beneath the broadened spectral lineshapes of molecular liquids giving insight into the internal mechanisms of energy transfer and decoherence. An excellent candidate of this technique is liquid H2O, whose importance to chemistry and biology cannot be understated. Little is known about the

Darren Kraemer

2008-01-01

56

Bond-Valence Constraints on Liquid Water Structure  

Microsoft Academic Search

The recent controversy about the structure of liquid water pits a new model involving water molecules in relatively stable rings-and-chains structures against the standard model that posits water molecules in distorted tetrahedral coordination. Molecular dynamics (MD) simulationsboth classical and ab initioalmost uniformly support the standard model, but since none of them can yet reproduce all the anomalous properties of water,

Barry R. Bickmore; Kevin M. Rosso; I. David Brown; Sebastien N. Kerisit

2009-01-01

57

The puzzling unsolved mysteries of liquid water: Some recent progress  

Microsoft Academic Search

Water is perhaps the most ubiquitous, and the most essential, of any molecule on earth. Indeed, it defies the imagination of even the most creative science fiction writer to picture what life would be like without water. Despite decades of research, however, water's puzzling properties are not understood and 63 anomalies that distinguish water from other liquids remain unsolved. We

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

2007-01-01

58

A high pressure calorimetric experiment to validate the liquid-liquid critical point hypothesis in water  

Microsoft Academic Search

An experimental proposal to test the existence of a liquid-liquid critical point in water, based on high pressure calorimetric measurements, is presented on this paper. Considering the existence of an intramolecular correlation in the water molecule we show how the response of the specific heat at high pressure is different depending on the existence, or not, of the second critical

Manuel I. Marques

2007-01-01

59

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.

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

2009-01-01

60

Point Mutations in A? Induce Polymorphic Aggregates at Liquid/Solid Interfaces  

PubMed Central

A pathological hallmark of Alzheimer’s disease (AD), a late onset neurodegenerative disease, is the development of neuritic amyloid plaques, composed predominantly of aggregates of the ?-amyloid (A?) peptide. It has been demonstrated that A? can aggregate into a variety of polymorphic aggregate structures under different chemical environments, and a potentially important environmental factor in dictating aggregate structure is the presence of surfaces. There are also several mutations clustered around the central hydrophobic core of A? (E22G Arctic mutation, E22K Italian mutation, D23N Iowa mutation, and A21G Flemish mutation). These mutations are associated with hereditary diseases ranging from almost pure cerebral amyloid angiopathy (CAA) to typical Alzheimer’s disease pathology. The goal of this study was to determine how these mutations influence the morphology of A? aggregates under free solution conditions and at an anionic surface/liquid interface. While the rate of formation of specific aggregates was altered by mutations in A? under free solution conditions, the respective aggregate morphologies were similar. However, aggregation occurring directly on a negatively charged mica surface resulted in distinct aggregate morphologies formed by different mutant forms of A?. These studies provide insight into the potential role anionic surfaces play in dictating the formation of A? polymorphic aggregate structures.

2011-01-01

61

Radiation affected liquid fuel burning on water  

SciTech Connect

A model for the radiation affected liquid flue burning on water is developed which improves substantially on an existing model by including the turbulent fire plume and the explicit effects (hotness and thickness) of fire radiation. In achieving these objects, the experimental literature on the flame height and velocity is utilized. The fire plume above the slick is divided into three regions: the continuous flame; the intermittent flame; and the thermal plume. To described the fire plume, Taylor's entrainment model is used which assumes top-hat profiles for the radial velocity and temperature and relates the entrainment and vertical velocities at a given height. The contributions from gaseous combustion products, mainly CO{sub 2} and H{sub 2}O, as well as from particulate matter to radiative heat transfer are also accounted for. Both linear and nonlinear solutions are obtained and compared to examine the accuracy of the usual approach of linearization in the radiative transport equations. The effect of radiation on fuel burning is demonstrated as a function of the flame hotness and optical thickness. Radiation is shown to lower the temperatures in the high temperature region of the flame and raise the temperatures in the low temperature region near the fuel surface. It is further shown that fuel burning increases monotonically with increase in radiation effects. It is concluded that the contribution of fire radiation of fuel burning is substantial and may exceed that of conduction heat transfer by an order of magnitude. The model is also compared with available data for crude oil burning on water, yielding reasonable trends within the uncertainty of the experimental literature.

Alramadhan, M.A.

1989-01-01

62

Stability of liquid saline water on present day Mars  

NASA Astrophysics Data System (ADS)

Perchlorate salts (mostly magnesium and sodium perchlorate) have been detected on Mars' arctic soil by the Phoenix lander, furthermore chloride salts have been found on the Meridiani and Gusev sites and on widespread deposits on the southern Martian hemisphere. The presence of these salts on the surface is not only relevant because of their ability to lower the freezing point of water, but also because they can absorb water vapor and form a liquid solution (deliquesce). We show experimentally that small amounts of sodium perchlorate (˜ 1 mg), at Mars atmospheric conditions, spontaneously absorb moisture and melt into a liquid solution growing into ˜ 1 mm liquid spheroids at temperatures as low as 225 K. Also mixtures of water ice and sodium perchlorate melt into a liquid at this temperature. Our results indicate that salty environments make liquid water to be locally and sporadically stable on present day Mars.

Zorzano, M.-P.; Mateo-Martí, E.; Prieto-Ballesteros, O.; Osuna, S.; Renno, N.

2009-10-01

63

Long-term evolution of transient liquid water on Mars  

NASA Astrophysics Data System (ADS)

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

Richardson, Mark I.; Mischna, Michael A.

2005-03-01

64

Energy loss of swift protons in liquid water and ethanol  

NASA Astrophysics Data System (ADS)

Energy loss measurement has been performed for the first time for MeV energy hydrogen ions passing through a liquid jet target produced by our newly developed liquid-in-vacuum apparatus. Liquid jet targets of water and ethanol were ejected into vacuum through an aperture of 20 ?m in diameter. Preliminary experimental results of energy loss spectra are reported. It was found that the energy loss of swift protons in liquids are slightly different from the conventional stopping power data obtained from the SRIM code. However, this discrepancy is possibly attributable to our incorrect estimation of the liquid jet diameter.

Itoh, A.; Kaneda, M.; Satoh, S.; Ishii, K.; Tsuchida, H.

2006-04-01

65

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

66

Evaporation rate of graphite liquid marbles: comparison with water droplets.  

PubMed

Liquid marbles are liquid drops made completely nonwetting by encapsulating the drop with a hydrophobic powder. The absence of contact with the substrate avoids contamination problems and produces high marble displacement velocities. Liquid marbles behave as microreservoirs of liquids able to move without any leakage and are promising candidates to be applied in biomedical and genetic analysis where 2D microfluidics and lab-on-a-chip methods are used. The lifetime of a liquid marble depends on the chemical nature and particle size of the hydrophobic powder as well as the liquid used to form it. There is a need for chemically inert liquid marbles, which can be used over sufficiently long periods for industrial applications. In this work, we successfully synthesized graphite liquid marbles for the first time by encapsulating graphite micropowder on water droplets and determined their evaporation periods and useful lifetimes in constant relative humidity and temperature conditions in a closed chamber. The evaporation rates of graphite liquid marbles were compared with the rates of pure water droplets in the same conditions, and it was found that they had nearly twice the lifetime of pure water droplets. The use of chemically inert graphite particles having electrical conductivity and dry lubrication properties to form a liquid marble may be a starting point for their successful use in microfluidics, genetic analysis, antifouling, wear-free micromachine, electromechanical actuator, and valve applications. PMID:19499944

Dandan, Merve; Erbil, H Yildirim

2009-07-21

67

Anatomy of competing quantum effects in liquid water.  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

68

Recent Liquid Water in the Polar Regions of Mars  

NASA Astrophysics Data System (ADS)

The potential presence of liquid water on a planetary body during a given epoch is important to both climatology and exobiology. Our modeling of the martian surface heat balance at high latitudes and obliquities in the recent past (i.e., during the last 100 m.y.) indicates that liquid water has been stable during local spring and summer in the polar regions of Mars. Previous martian climate models concluded that liquid water would not be stable at high obliquity. However, our model differs from these previous models in three crucial respects: A more detailed atmospheric radiative transfer model is employed to assess the surface heating due to a water vapor greenhouse; the effects of atmospheric dust are incorporated; and, perhaps most importantly, idealized sublimation into a dry atmosphere is not assumed. Our results indicate that liquid water would indeed be stable at the martian poles at obliquities of 45 degrees and higher during much of local spring and summer. Furthermore, using the best estimates of martian near-polar surface properties such as thermal inertia and albedo, we also find that such liquid water "oases" would also be stable just off of the northern polar cap at obliquities as low as 35 degrees. The importance of such stable liquid water to climatology is twofold, as water not only influences climate but also readily erodes the surface, thereby recording past climate change. We will attempt to discuss the geologic evidence for such change in the context of new observations from Mars Global Surveyor.

Pathare, A. V.; Paige, D. A.

1998-01-01

69

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.

Andersson, Ove

2011-01-01

70

The relationship between liquid, supercooled and glassy water  

Microsoft Academic Search

That water can exist in two distinct `glassy' forms - low- and high-density amorphous ice - may provide the key to understanding some of the puzzling characteristics of cold and supercooled water, of which the glassy solids are more-viscous counterparts. Recent experimental and theoretical studies of both liquid and glassy water are now starting to offer the prospect of a

Osamu Mishima; H. Eugene Stanley

1998-01-01

71

Modeling vadose zone liquid water fluxes: Infiltration, runoff, drainage, interflow  

Microsoft Academic Search

Because of the large water storage capacity of soil relative to the atmosphere, changes in soil moisture storage can significantly affect the regional atmospheric budgets of water and energy on monthly, seasonal and longer time scales. Therefore proper modeling of soil liquid water processes is essential to a correct representation of the climate system.This study focuses on the class of

Peter J. Wetzel; Xu Liang; Parviz Irannejad; Aaron Boone; Joel Noilhan; Yaping Shao; Chris Skelly; Yongkang Xue; Zong Liang Yang

1996-01-01

72

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

Microsoft Academic Search

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

Ernesto Vercher; M. Pilar Peña; Antoni Martinez-Andreu

1996-01-01

73

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

Microsoft Academic Search

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

Ernesto Vercher; M. Pilar Peña; Antoni Martinez-Andreu

1996-01-01

74

Adsorbed water and thin liquid films on Mars  

NASA Astrophysics Data System (ADS)

At present, bulk liquid water on the surface and near-subsurface of Mars does not exist due to the scarcity of condensed- and gas-phase water, pressure and temperature constraints. Given that the nuclei of soil and ice, that is, the soil solid and ice lattice, respectively, are coated with adsorbed and/or thin liquid films of water well below 273 K and the availability of water limits biological activity, we quantify lower and upper limits for the thickness of such adsorbed/water films on the surface of the Martian regolith and for subsurface ice. These limits were calculated based on experimental and theoretical data for pure water ice and water ice containing impurities, where water ice containing impurities exhibit thin liquid film enhancements, ranging from 3 to 90. Close to the cold limit of water stability (i.e. 273 K), thin liquid film thicknesses at the surface of the Martian regolith is 0.06 nm (pure water ice) and ranges from 0.2 to 5 nm (water ice with impurities). An adsorbed water layer of 0.06 nm implies a dessicated surface as the thickness of one monolayer of water is 0.3 nm but represents 0.001-0.02% of the Martian atmospheric water vapour inventory. Taking into account the specific surface area (SSA) of surface-soil (i.e. top 1 mm of regolith and 0.06 nm adsorbed water layer), shows Martian surface-soil may contain interfacial water that represents 6-66% of the upper- and lower-limit atmospheric water vapour inventory and almost four times and 33%, the lower- and upper-limit Martian atmospheric water vapour inventory. Similarly, taking the SSA of Martian soil, the top 1 mm or regolith at 5 nm thin liquid water thickness, yields 1.10×1013 and 6.50×1013 litres of waters, respectively, 55-325 times larger than Mars' atmospheric water vapour inventory. Film thicknesses of 0.2 and 5 nm represent 2.3×104-1.5×106 litres of water, which is 6.0×10-7-4.0×10-4%, respectively, of a 10 pr ?m water vapour column, and 3.0×10-6-4.0×10-4% and 6.0×10-6-8.0×10-4%, respectively, of the Martian atmospheric water vapour inventory. Thin liquid film thicknesses on/in subsurface ice were investigated via two scenarios: (i) under the idealistic case where it is assumed that the diurnal thermal wave is equal to the temperature of ice tens of centimetres below the surface, allowing for such ice to experience temperatures close to 273 K and (ii) under the, likely, realistic scenario where the diurnal thermal wave allows for the maximum subsurface ice temperature of 235 K at 1 m depth between 30°N and 30°S. Scenario 1 yields thin liquid film thicknesses ranging from 11 to 90 nm; these amounts represent 4×106-3.0×107 litres of water. For pure water ice, Scenario 2 reveals that the thickness of thin liquid films contained on/within Martian subsurface is less than 1.2 nm, several molecular layers thick. Conversely, via the effect of impurities at 235 K allows for a thin liquid film thickness on/within subsurface ice of 0.5 nm, corresponding to 6.0×104 litres of water. The existence of thin films on Mars is supported by data from the Mars Exploration Rovers (MERs) Spirit and Opportunity's Alpha Proton X-ray Spectrometer instrumentation, which have detected increased levels of bromine beneath the immediate surface, suggestive of the mobilization of soluble salts by thin films of liquid water towards local cold traps. These findings show that biological activity on the Martian surface and subsurface is not limited by nanometre dimensions of available water.

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

2012-07-01

75

High pressure vapor-liquid and vapor-liquid-liquid equilibria for systems containing supercritical carbon dioxide, water and furfural  

Microsoft Academic Search

We measured vapor-liquid equilibrium for a binary system CO2?furfural at temperatures of 303 and 323 K and vapor-liquid-liquid equilibrium for a ternary system CO2?water?furfural at temperatures of 303, 323 and 343 K and pressure of 5 MPa to obtain fundamental data for concentration of furfural by using three phase separation technique. Furthermore the experimental data were compared with results calculated

Takeshi Sako; Tsutomu Sugeta; Noriaki Nakazawa; Katsuto Otake; Masahito Sato; Katsuo Ishihara; Masahiro Kato

1995-01-01

76

Bilayer ice and alternate liquid phases of confined water  

NASA Astrophysics Data System (ADS)

We report results from molecular dynamics simulations of the freezing and melting, at ambient temperature (T=300 K), of a bilayer of liquid water induced by either changing the distance between two confining parallel walls at constant lateral pressure or by lateral compression at constant plate separation. Both transitions are found to be first order. The system studied consisted of 1200 water molecules that were described by the TIP5P model. The in-plane symmetry of the oxygen atoms in the ice bilayer was found to be rhombic with a distorted in-registry arrangement. Above and below the stability region of the ice bilayer we observed two bilayer phases of liquid water that differ in the local ordering at the level of the second shell of nearest neighbors and in the density profile normal to the plane, yielding two liquid phases with different densities. These results suggest the intriguing possibility of a liquid-liquid transition of water, confined to a bilayer, at regions where the ice bilayer is unstable with respect to either of the liquid phases. In addition, we find that under the same conditions, water confined to 3-8 layers remains in the liquid phase (albeit stratification of the transverse density profile) with values of the lateral diffusion coefficient comparable to that of the bulk.

Zangi, Ronen; Mark, Alan E.

2003-07-01

77

Room Temperature Ionic Liquids for Separating Organics from Produced Water  

Microsoft Academic Search

The distribution of polar organic compounds typical of water contaminants (organic acids, alcohols, and aromatic compounds) associated with oil and gas production was measured between water and nine hydrophobic, room?temperature ionic liquids. The ionic liquids used in this study were 1?butyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?hexyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?octyl?3?methylimidazolium bistrifluoromethanesulfonylimide, 1?butyl?3?methylimidazolium hexafluorophosphate, trihexyltetradecylphosphonium bistrifluoromethanesulfonylimide, 1?butyl?1?methyl?pyrrolidinium bistrifluoromethanesulfonylimide, trihexyltetradecylphosphonium dodecylbenzenesulfonate, tributyltetradecylphosphonium dodecylbenzenesulfonate, and trihexyltetradecylphosphonium methanesulfonate. Sensitivity

J. McFarlane; W. B. Ridenour; H. Luo; R. D. Hunt; D. W. DePaoli; R. X. Ren

2005-01-01

78

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.

79

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)

1995-09-01

80

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

NASA Astrophysics Data System (ADS)

Measurements of the stable isotope ratios of liquid water allow determination of water flowpaths, residence times in catchments, and groundwater migration. Previously, discrete water samples have been collected and transported to an IRMS lab for isotope characterization. Due to the expense and labor associated with such sampling, isotope studies have thus been generally limited in scope and in temporal resolution. We report on the recent development of the first Isotopic Water Analyzer that simultaneously quantifies ?2H, ?17O and ?18O in liquid water or in water vapor from different natural water sources (e.g., rain, snow, streams and groundwater). In High-Throughput mode, the IWA can report measurements at the unprecedented rate of over 800 injections per day, which yields more than 140 total unknown and reference samples per day (still with 6 injections per measurement). This fast time response provides isotope hydrologists with the capability to study dynamic changes in ? values quickly (minutes) and over long time scales (weeks, months), thus enabling studies of mixing dynamics in snowmelt, canopy throughfall, stream mixing, and allows for individual precipitation events to be independently studied. In addition, the same IWA can also record fast measurements of isotopic water vapor (?2H, ?17O, ?18O) in real time (2 Hz data rate or faster) over a range of mole fractions greater than 60000 ppm H2O in air. Changing between operational modes requires a software command, to enable the user to switch from measuring liquid water to measuring water vapor, or vice versa. The new IWA, which uses LGR's patented Off-axis ICOS technology, incorporates proprietary internal thermal control for stable measurements with essentially zero drift despite changes in ambient temperature (over the entire range from 0-45 degrees C). Measurements from recent field studies using the IWA will be presented.

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

2012-04-01

81

Ionic liquid based dispersive liquid–liquid microextraction of aromatic amines in water samples  

Microsoft Academic Search

In this work, a new microextraction method termed ionic liquid based dispersive liquid–liquid microextraction (IL-DLLME) was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices. After extraction the ionic liquid (IL) phase was injected directly into the high performance liquid chromatography (HPLC) system for determination. Some parameters that might affect the extraction efficiency were optimized. Under

Yun Chang Fan; Zheng Liang Hu; Mei Lan Chen; Chao Shen Tu; Yan Zhu

2008-01-01

82

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

83

Production of Liquid Water by Impacts onto Icy Bodies  

NASA Astrophysics Data System (ADS)

Melting of H2O ice during planetary impact events is a widespread phenomenon. As relatively low shock pressures are required to melt ice, large volumes of liquid may be produced. Depending on the size of the event, the liquid water may persist for long time scales. However, knowledge of the volume and spatial distribution of liquid water produced from an impact is necessary to draw conclusions about the longevity of the liquid water. Using the new 5-phase model equation of state for H2O (Stewart & Senft, MAPS, 2008) in CTH hydrocode simulations, we calculate the volume of ice that is melted for a wide range of impact conditions and derive scaling laws as a function of initial temperature, projectile size and impact velocity. We also consider impacts onto mixtures of ice and silicates. Using new experimental results for how energy is partitioned in a shocked ice-quartz mixture (Kraus et al., EPSL, submitted), we determine the maximum amount of liquid water produced in ice-silicate mixtures. Interestingly, there is a range of silicate to ice ratios that will result in a greater amount of liquid water production than if the same impact occurred onto a body of pure ice. Support was provided by the DOE NNSA SSGF program under grant No. DE-FC52-08NA28752 and NASA under grant No. NNX06AC13G

Kraus, Richard; Stewart, S. T.

2009-09-01

84

Order parameter defining liquid-liquid transition in water  

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

85

Solid Supported Liquid–Liquid Extraction of Chemical Warfare Agents and Related Chemicals from Water  

Microsoft Academic Search

Solid-supported liquid–liquid extraction was optimized to extract the chemical warfare agents and their non-toxic analogues\\u000a from water. The developed method was compared to the conventionally used liquid–liquid extraction. This method yielded high\\u000a recoveries (70–80%) of non-toxic analogues of chemical warfare agents and good recoveries (65–75%) of the nerve agent sarin\\u000a and Lewisite-III. The limits of detection of non-toxic analogues of

Pankaj K. Kanaujia; Deepak Pardasani; Vijay Tak; D. K. Dubey

2009-01-01

86

Identification of Cryptosporidium spp. Oocysts in United Kingdom Noncarbonated Natural Mineral Waters and Drinking Waters by Using a Modified Nested PCR-Restriction Fragment Length Polymorphism Assay  

PubMed Central

We describe a nested PCR-restriction fragment length polymorphism (RFLP) method for detecting low densities of Cryptosporidium spp. oocysts in natural mineral waters and drinking waters. Oocysts were recovered from seeded 1-liter volumes of mineral water by filtration through polycarbonate membranes and from drinking waters by filtration, immunomagnetizable separation, and filter entrapment, followed by direct extraction of DNA. The DNA was released from polycarbonate filter-entrapped oocysts by disruption in lysis buffer by using 15 cycles of freeze-thawing (1 min in liquid nitrogen and 1 min at 65°C), followed by proteinase K digestion. Amplicons were readily detected from two to five intact oocysts on ethidium bromide-stained gels. DNA extracted from Cryptosporidium parvum oocysts, C. muris (RN 66), C. baileyi (Belgium strain, LB 19), human-derived C. meleagridis, C. felis (DNA from oocysts isolated from a cat), and C. andersoni was used to demonstrate species identity by PCR-RFLP after simultaneous digestion with the restriction enzymes DraI and VspI. Discrimination between C. andersoni and C. muris isolates was confirmed by a separate, subsequent digestion with DdeI. Of 14 drinking water samples tested, 12 were found to be positive by microscopy, 8 were found to be positive by direct PCR, and 14 were found to be positive by using a nested PCR. The Cryptosporidium species detected in these finished water samples was C. parvum genotype 1. This method consistently and routinely detected >5 oocysts per sample.

Nichols, R. A. B.; Campbell, B. M.; Smith, H. V.

2003-01-01

87

On the resurfacing of Ganymede by liquid water volcanism  

NASA Astrophysics Data System (ADS)

A long-popular model for producing Ganymede's bright terrain involves flooding of low-lying graben with liquid water, slush, or warm, soft ice. The model suffers from major problems, however, including the absence of obvious near-surface heat sources, the negative buoyancy of liquid water, and the lack of a mechanism for confining the flows to graben floors. We present new models for cryovolcanic resurfacing to overcome these difficulties. Tidal heating within an ancient Laplace-like orbital resonance (Showman and Malhotra 1997, Icarus 127, 93; Showman et al., 1997, Icarus 129, 367) provides a plausible heat source and could allow partial melting to occur as shallow as 5-10 km depth. Our favored mechanism for delivering this water to the surface invokes the fact that topography—such as a global set of graben—causes subsurface pressure gradients that can pump water or slush upward onto the floors of topographic lows (graben) despite the negative buoyancy of the liquid. These eruptions can occur only within the topographic lows; furthermore, as the low areas become full, the pressure gradients disappear and the resurfacing ceases. This provides an explanation for the observed straight dark-bright terrain boundaries: water cannot overflow the graben, so resurfacing rarely embays craters or other rough topography. Pure liquid water can be pumped to the surface from only 5-10 km depth, but macroscopic bodies of slush ascending within fractures can reach the surface from much greater depths due to the smaller negative buoyancy of slush. A challenge for these models is the short predicted gravitational relaxation timescale of topographic features at high heat flows; the resurfacing must occur before the graben topography disappears. We also evaluate alternate resurfacing mechanisms, such as pumping of liquid water to the surface by thermal expansion stresses and buoyant rise of water through a silicate-contaminated crust that is denser than liquid water, and conclude that they are unlikely to explain Ganymede's bright terrain.

Showman, Adam P.; Mosqueira, Ignacio; Head, James W.

2004-12-01

88

Satellite remote sensing of the liquid water sensitivity in water clouds  

Microsoft Academic Search

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

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

2001-01-01

89

Detection of Subsurface Liquid Water Using Magnetotellurics on Mars  

Microsoft Academic Search

The characterization of past or present water on Mars remains a core goal of the Mars exploration program, representing a cross-cutting theme that ties together investigations relevant to life, climate, geology, and the identification of sites for future exploratory landed missions. Passive, low frequency electromagnetic (EM) soundings of the subsurface can identify salinated liquid water at depths ranging from hundreds

G. T. Delory; R. E. Grimm; T. Nielsen; W. M. Farrell

2005-01-01

90

Liquid effluent study: Ground water characterization data  

SciTech Connect

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

Not Available

1990-08-01

91

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

92

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

93

Oiling out or molten hydrate-liquid-liquid phase separation in the system vanillin-water.  

PubMed

Vanillin crystals in a saturated aqueous solution disappear and a second liquid phase emerges when the temperature is raised above 51 degrees C. The phenomenon has been investigated with crystallization and equilibration experiments, using DSC, TGA, XRD and hot-stage microscopy for analysis. The new liquid solidifies on cooling, appears to melt at 51 degrees C, and has a composition corresponding to a dihydrate. However, no solid hydrate can be detected by XRD, and it is shown that the true explanation is that a liquid-liquid phase separation occurs above 51 degrees C where the vanillin-rich phase has a composition close to a dihydrate. To our knowledge, liquid-liquid phase separation has not previously been reported for the system vanillin-water, even though thousands of tonnes of vanillin are produced globally every year. PMID:17497737

Svärd, Michael; Gracin, Sandra; Rasmuson, Ake C

2007-09-01

94

Metastable statics and dynamics of liquid water  

Microsoft Academic Search

Water is perhaps the most ubiquitous, and the most essential, of any molecule on earth. Indeed, H2O challenges the imagination of even the most creative science fiction writers (such as K. Vonnegut) to picture what life would be like without water, and one often hears the adage \\

H. Eugene Stanley

95

Water and other tetrahedral liquids: order, anomalies and solvation.  

PubMed

In order to understand the common features of tetrahedral liquids with water-like anomalies, the relationship between local order and anomalies has been studied using molecular dynamics simulations for three categories of such liquids: (a) atomistic rigid-body models for water (TIP4P, TIP4P/2005, mTIP3P, SPC/E), (b) ionic melts, BeF(2) (TRIM model) and SiO(2) (BKS potential) and (c) Stillinger-Weber liquids parametrized to model water (mW) and silicon. Rigid-body, atomistic models for water and the Stillinger-Weber liquids show a strong correlation between tetrahedral and pair correlation order and the temperature for the onset of the density anomaly is close to the melting temperature. In contrast, the ionic melts show weaker and more variable degrees of correlation between tetrahedral and pair correlation metrics, and the onset temperature for the density anomaly is more than twice the melting temperature. In the case of water, the relationship between water-like anomalies and solvation is studied by examining the hydration of spherical solutes (Na(+), Cl(-), Ar) in water models with different temperature regimes of anomalies (SPC/E, TIP4P and mTIP3P). For both ionic and nonpolar solutes, the local structure and energy of water molecules is essentially the same as in bulk water beyond the second-neighbour shell. The local order and binding energy of water molecules are not perturbed by the presence of a hydrophobic solute. In the case of ionic solutes, the perturbation is largely localized within the first hydration shell. The binding energies for the ions are strongly dependent on the water models and clearly indicate that the geometry of the partial charge distributions, and the associated multipole moments, play an important role. However the anomalous behaviour of the water network has been found to be unimportant for polar solvation. PMID:22739063

Jabes, B Shadrack; Nayar, Divya; Dhabal, Debdas; Molinero, Valeria; Chakravarty, Charusita

2012-06-27

96

Physical and Thermodynamical Evidence of Liquid Water on Mars  

NASA Astrophysics Data System (ADS)

The objective of the Phoenix Mars mission is to determine if Mars' polar region can support life. Since liquid water is a basic ingredient for life, as we know, an important goal of the mission is to determine if liquid water exists at the landing site. It is believed that a layer of martian soil preserves ice by forming a barrier against sublimation, but that exposed ice sublimates without the formation of the liquid phase. Here we show physical and thermodynamical evidence that besides ice, liquid saline-water exists in areas disturbed by the Phoenix lander. Moreover, we show that the thermodynamics of freezing/thaw cycles ranging from diurnal to climatic time-scales leads to the formation of saline solutions with freezing temperatures much higher than current summer ground temperatures where surface ice is believed to exist near the surface. Thus, we hypothesize that liquid saline-water is common on Mars. This discovery has important implications for the stability of water, weathering, glaciology, mineralogy, geochemistry and the habitability of Mars.

Renno, N. O.; Bos, B. J.; Clark, B. C.; Drube, L.; Goetz, W.; Keller, H. U.; Kounaves, S.; Leer, K.; Lemmon, M.; Madsen, M. B.; Markiewicz, W.; Marshall, J.; Mackay, C.; Mehta, M.; Mellon, M.; Smith, M.; Tamppari, L. K.; Smith, P.; Stoker, C.; Tamppari, L.; Wood, S. U.; Young, S. M.; Zent, A.; Fisher, D.

2008-12-01

97

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

SciTech Connect

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

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

2008-01-01

98

Communication: Protein dynamical transition vs. liquid-liquid phase transition in protein hydration water  

NASA Astrophysics Data System (ADS)

In this work, we compare experimental data on myoglobin hydrated powders from elastic neutron scattering, broadband dielectric spectroscopy, and differential scanning calorimetry. Our aim is to obtain new insights on the connection between the protein dynamical transition, a fundamental phenomenon observed in proteins whose physical origin is highly debated, and the liquid-liquid phase transition (LLPT) possibly occurring in protein hydration water and related to the existence of a low temperature critical point in supercooled water. Our results provide a consistent thermodynamic/dynamic description which gives experimental support to the LLPT hypothesis and further reveals how fundamental properties of water and proteins are tightly related.

Schirò, Giorgio; Fomina, Margarita; Cupane, Antonio

2013-09-01

99

Free energy surface of ST2 water near the liquid-liquid phase transition.  

PubMed

We carry out umbrella sampling Monte Carlo simulations to evaluate the free energy surface of the ST2 model of water as a function of two order parameters, the density and a bond-orientational order parameter. We approximate the long-range electrostatic interactions of the ST2 model using the reaction-field method. We focus on state points in the vicinity of the liquid-liquid critical point proposed for this model in earlier work. At temperatures below the predicted critical temperature we find two basins in the free energy surface, both of which have liquid-like bond orientational order, but differing in density. The pressure and temperature dependence of the shape of the free energy surface is consistent with the assignment of these two basins to the distinct low density and high density liquid phases previously predicted to occur in ST2 water. PMID:23343283

Poole, Peter H; Bowles, Richard K; Saika-Voivod, Ivan; Sciortino, Francesco

2013-01-21

100

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

101

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

NASA Astrophysics Data System (ADS)

Measurements of the stable isotope ratios of liquid water (?2H and ?18O) allow determination of water flowpaths, residence times in catchments, and groundwater migration. In the past, discrete water samples have been collected and transported to an IRMS lab for isotope characterization. Due to the expense and labor associated with such sampling, isotope studies have thus been generally limited in scope and in temporal resolution. We report on the recent development of a new field-portable Isotopic Water Analyzer (IWA-35EP) that accurately quantifies ?2H and ?18O of different natural water sources (e.g., rain, snow, streams and groundwater) at the unprecedented rate of 1080 injections per day, which yields 180 total unknown and reference samples per day (150 unknown samples per day), or 1 measurement of an unknown sample in less than 10 minutes (with 6 injections per measurement). This fast time response provides isotope hydrologists with the capability to study dynamic changes in ? values quickly (minutes) and over long time scales (weeks, months), thus enabling studies of mixing dynamics in snowmelt, canopy throughfall, stream mixing, and allows for individual precipitation events to be independently studied. In addition, the same IWA can also record fast measurements of isotopic water vapor (?18O and ?2H) in real time (2 Hz data rate or faster) over a range of mole fractions greater than 60000 ppm H2O in air. Changing between operational modes requires a software command, to enable the user to switch from measuring liquid water to measuring water vapor, or vice versa. The new IWA, which uses LGR's patented Off-axis ICOS technology, incorporates proprietary internal thermal control for stable measurements with essentially zero drift. Measurements from recent field studies using the IWA will be presented.

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

2011-12-01

102

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

1996-01-01

103

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)

1996-07-01

104

Liquid–liquid equilibria of ternary mixture (propargyl alcohol + diisopropyl ether + water)  

Microsoft Academic Search

The liquid–liquid equilibria (LLE) of ternary mixture (propargyl alcohol+diisopropyl ether+water) were measured under atmospheric pressure and at different temperatures of 297.25, 304.35, 313.15, and 323.25K. It was found that the end points of tie-lines at the four temperatures were located almost on a common solubility curve but the tie-lines possessed different slopes that described different equilibrium relations. A comparison of

Kongmeng Ye; Jia Wu; Guo’an Deng

2007-01-01

105

Determination of organic compounds in water using dispersive liquid–liquid microextraction  

Microsoft Academic Search

A new microextraction technique termed dispersive liquid–liquid microextraction (DLLME) was developed. DLLME is a very simple and rapid method for extraction and preconcentration of organic compounds from water samples. In this method, the appropriate mixture of extraction solvent (8.0?L C2Cl4) and disperser solvent (1.00mL acetone) are injected into the aqueous sample (5.00mL) by syringe, rapidly. Therefore, cloudy solution is formed.

Mohammad Rezaee; Yaghoub Assadi; Mohammad-Reza Milani Hosseini; Elham Aghaee; Fardin Ahmadi; Sana Berijani

2006-01-01

106

Dynamical behavior near a liquid-liquid phase transition in simulations of supercooled water.  

PubMed

We examine the behavior of the diffusion coefficient of the ST2 model of water over a broad region of the phase diagram via molecular dynamics simulations. The ST2 model has an accessible liquid-liquid transition between low-density and high-density phases, making the model an ideal candidate to explore the impacts of the liquid-liquid transition on dynamics. We locate characteristic dynamical loci in the phase diagram and compare them with the previously investigated thermodynamic loci. The low-density liquid phase shows a crossover from non-Arrhenius to Arrhenius behavior, signaling the onset of a crossover from fragile-to-strong behavior. We explain this crossover in terms of the asymptotic approach of the low-density liquid to a random tetrahedral network and show that the temperature dependence of the diffusion coefficient over a wide temperature range can be simply related to the concentration of defects in the network. Our findings thus confirm that the low-density phase of ST2 water is a well-defined metastable liquid. PMID:21866981

Poole, Peter H; Becker, Stephen R; Sciortino, Francesco; Starr, Francis W

2011-08-26

107

Research Spotlight: Gullies on Mars indicate presence of liquid water  

NASA Astrophysics Data System (ADS)

Present-day conditions on Mars were thought to prevent water from existing as a liquid on the planet's surface, but recent studies have pointed to the existence of liquid water. Now observations of gully activity on Mars provide further indications of the presense of transient liquid water.Reiss et al. studied images of the Russell crater dune field on Mars taken by the High Resolution Imaging Science Experiment (HiRISE) from November 2006 to May 2009. They observed that the length of a 2-meter-wide gully channel had increased by about 50 meters in 1 year and about 120 meters in 2 years. On the basis of the morphology of the channel and other factors, the researchers believe that these changes in the length of the gully are best explained by erosional processes triggered by the melting of small amounts of water ice. This adds to the growing body of evidence that transient liquid water can exist on Mars.

Tretkoff, Ernie

108

How the Liquid-Liquid Transition Affects Hydrophobic Hydration in Deeply Supercooled Water  

NASA Astrophysics Data System (ADS)

We determine the phase diagram of liquid supercooled water by extensive computer simulations using the TIP5P-E model [J. Chem. Phys. 120, 6085 (2004), JCPSA6, 0021-9606, 10.1063/1.1652434]. We find that the transformation of water into a low density liquid in the supercooled range strongly enhances the solubility of hydrophobic particles. The transformation of water into a tetrahedrally structured liquid is accompanied by a minimum in the hydration entropy and enthalpy. The corresponding change in sign of the solvation heat capacity indicates a loss of one characteristic signature of hydrophobic hydration. The observed behavior is found to be qualitatively in accordance with the predictions of the information theory model of Garde et al. [Phys. Rev. Lett. 77, 4966 (1996), PRLTAO, 0031-9007, 10.1103/PhysRevLett.77.4966].

Paschek, Dietmar

2005-06-01

109

Hydrogen bonds in liquid water are broken only fleetingly  

Microsoft Academic Search

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

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

2005-01-01

110

Is there a second critical point in liquid water?  

Microsoft Academic Search

The supercooled and stretched regions of the phase diagram of simulated liquid water are investigated by calculating the equation of state of the ST2 and TIP4P pair-potentials. We find that simulated water does not display a re-entrant spinodal and that the projection of the density maximum line in the plane of pressure and temperature becomes positively sloped on stretching. The

H. E. Stanley; C. A. Angell; U. Essmann; M. Hemmati; P. H. Poole; F. Sciortino

1994-01-01

111

Liquid-liquid immiscibility in single-component network-forming fluids: Model calculations and implications for polyamorphism in water  

SciTech Connect

Analytical calculations and Monte Carlo simulations of a lattice model of a tetravalent network-forming fluid show liquid-liquid immiscibility at low temperatures. Three types of phase behavior are found to occur: vapor-liquid equilibrium, vapor-liquid equilibrium plus liquid-liquid immiscibility with an upper critical temperature, and vapor-liquid equilibrium plus closed-loop liquid-liquid immiscibility. The coexisting liquids differ appreciably in density, structure, and molecular dynamics. The low-density liquid displays more structured, open networks, and slower translational and network-restructuring dynamics than the high-density liquid. The model provides useful insights into the molecular basis of low-temperature immiscibility in network-forming fluids, and its relation to the unusual transition between distinct amorphous phases in vitreous water.

Roberts, C.J.; Karayiannakis, G.A.; Debenedetti, P.G. [Princeton Univ., NJ (United States). Dept. of Chemical Engineering

1998-08-01

112

Molecular dynamics of the water liquid-vapor interface.  

PubMed

The results of molecular dynamics calculations on the equilibrium interface between liquid water and its vapor at 325 K are presented. For the TIP4P model of water intermolecular pair potentials, the average surface dipole density points from the vapor to the liquid. The most common orientations of water molecules have the C2 nu molecular axis roughly parallel to the interface. The distributions are quite broad and therefore compatible with the intermolecular correlations characteristic of bulk liquid water. All near-neighbor pairs in the outermost interfacial layers are hydrogen bonded according to the common definition adopted here. The orientational preferences of water molecules near a free surface differ from those near rigidly planar walls which can be interpreted in terms of patterns found in hexagonal ice 1. The mean electric field in the interfacial region is parallel to the mean polarization which indicates that attention cannot be limited to dipolar charge distributions in macroscopic descriptions of the electrical properties of this interface. The value of the surface tension obtained is 132 +/- 46 dyn/cm, significantly different from the value for experimental water of 68 dyn/cm at 325 K. PMID:11539733

Wilson, M A; Pohorille, A; Pratt, L R

1987-01-01

113

Isotopic Exchange Rate Constant between Snow and Liquid Water  

Microsoft Academic Search

Isotopic exchange rate between liquid water and ice is crucial in determining the isotopic evolution of a snowpack and its melt. The rate constant for oxygen isotopic exchange has been reported by Taylor et al. [2002] using three column melting experiments with different heights and melt rates. In this work, we obtained the hydrogen isotopic exchange rate constant using samples

J. Lee; X. Feng; E. S. Posmenrier; A. M. Faiia

2007-01-01

114

Structure in liquid water: A study of spatial distribution functions  

Microsoft Academic Search

Despite the fact that an enormous literature has now accumulated on the structure in liquid water, the focus has been primarily limited to the average radial distributions of particles; local (atomic) pair-density maps which span both the radial and the angular coordinates of the separation vector have remained largely unexplored. In this work, we have obtained the spatial distribution functions

I. M. Svishchev; P. G. Kusalik

1993-01-01

115

Comparison of Thermodynamic Properties of Simulated Liquid Silica and Water  

Microsoft Academic Search

We conduct extensive molecular dynamics computer simulations of a rigid-ion model of liquid silica [L.V. Woodcock et al., J. Chem. Phys. 65, 1565 (1976)], evaluating thermodynamic and transport properties over a wide range of pressure and temperature. We find numerous similarities with behavior found in simulations of supercooled water, including a line of density maxima that passes through a maximum

Peter H. Poole; Mahin Hemmati; C. Austen Angell

1997-01-01

116

Stopping Power of Liquid Water for alpha-Particles  

Microsoft Academic Search

THE mean stopping power of liquid water averaged over the whole range has been determined for natural alpha-particles by Michl1 and by Philipp2. These authors find values for the molecular stopping power which are higher by about 20 and 14 per cent respectively than those predicted by the Bragg law and the accepted atomic stopping powers of hydrogen and oxygen.

R. K. Appleyard

1949-01-01

117

Transient liquid water near an artificial heat source on Mars  

Microsoft Academic Search

Background: We consider the response of an icy regolith to a localized heat source using analytical and numerical models. Our motivation is to understand the implications of a landing failure in which a radioisotope power source is deposited along with terrestrial microbes within or near icy regolith, resulting in the production of liquid water and the proliferation of microbes. Method:

Michael H. Hecht; Ashwin R. Vasavada

2006-01-01

118

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

PubMed

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. PMID:19367794

Pierce, Flint; Tsige, Mesfin; Perahia, Dvora; Grest, Gary S

2008-12-18

119

Glass Transition in Biomolecules and the Liquid-Liquid Critical Point of Water  

NASA Astrophysics Data System (ADS)

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 CP 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.

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

2006-10-01

120

Liquid–liquid–solid equilibria for the quaternary system water+ethanol+1-pentanol+sodium chloride at 25°C  

Microsoft Academic Search

Salting-out effect can be used to improve the extraction of some solutes by modifying the solute distribution between two liquid phases. In this work we report the results obtained for the quaternary system water+ethanol+1-pentanol+sodium chloride at 25°C. All equilibrium regions (one liquid, two liquids, one liquid+one solid and two liquids+one solid zones) have been systematically studied. Tie lines and tie-triangles

M. M. Olaya; A. Botella; A. Marcilla

1999-01-01

121

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

122

Nanomechanics and dynamics of confined water and other liquids  

NASA Astrophysics Data System (ADS)

From oil recovery to molecular biology, nanoconfined water plays an important role in many areas of research. However, the mechanics and dynamics of nanoconfined water are not well understood. Over the last ten years, a number of groups have measured the mechanics of confined water using atomic force microscopy (AFM) or surface force apparatus (SFA) - often with contradictory results. At Wayne State University, we have developed high resolution AFMs for ultra-small amplitude, linear measurements of the mechanics and dynamics of confined liquids. We have shown that water shows a distinct slow-down in dynamics under confinement (PRB 2004), co-discovered a dynamic ``solidification'' in a model liquid (Langmuir 2006), and showed that normal and shear stiffness are closely related in confined liquids (Rev. Sci. Instr. 2008). Recently, we found dynamic solidification also in water layers (PRL 2010), a finding that explains the contradictory findings in earlier measurements and points to surprisingly complex behavior in this seemingly simple system. Here we will review these findings, as well as present new findings that show the profound effects of ion concentration on these dynamical effects, as well as measurements of colloidal systems, which illustrate that some findings at the molecular scale can be understood from purely geometric considerations and are not dependent on molecular-scale interactions.

Hoffmann, Peter; Khan, Shah

2012-02-01

123

Nanomechanics and dynamics of confined water and other liquids  

NASA Astrophysics Data System (ADS)

From oil recovery to molecular biology, nanoconfined water plays an important role in many areas of research. However, the mechanics and dynamics of nanoconfined water are not well understood. Over the last ten years, a number of groups have measured the mechanics of confined water using atomic force microscopy (AFM) or surface force apparatus (SFA) - often with contradictory results. At Wayne State University, we have developed high resolution AFMs for ultra-small amplitude, linear measurements of the mechanics and dynamics of confined liquids. We have shown that water shows a distinct slow-down in dynamics under confinement (PRB 2004), co-discovered a dynamic ``solidification'' in a model liquid (Langmuir 2006), and showed that normal and shear stiffness are closely related in confined liquids (Rev. Sci. Instr. 2008). Recently, we found dynamic solidification also in water layers (PRL 2010), a finding that explains the contradictory findings in earlier measurements and points to surprisingly complex behavior in this seemingly simple system. Here we will review these findings, as well as present new findings that show the profound effects of ion concentration on these dynamical effects, as well as measurements of colloidal systems, which illustrate that some findings at the molecular scale can be understood from purely geometric considerations and are not dependent on molecular-scale interactions.

Hoffmann, Peter

2012-10-01

124

Interfacial water - the only liquid water in the upper martian subsurface  

NASA Astrophysics Data System (ADS)

It is shown, after introducing the physics of liquid water on and in the upper surface of Mars, that interfacial water is the only liquid water on present days Mars. Water ice on a mineral surface is not generally stable. A microscopic liquid layer of "undercooled" liquid water must in a large range of temperatures evolve between ice and mineral due to the attractive van der Waals forces driven pressure, acting upon the ice. This pressure is followed by a freezing point depression, which may let the water liquid down to temperatures of about 180 K on Mars. This is the only liquid water, what can be expected to exist, at least temporarily, on recent Mars. The physics behind and the resulting "band of possible liquid water" between minimum liquidus temperature and the slightly higher frost point temperature in the p-T-parameter-space is described by a "Sandwich-model" with layers of ice (top), liquid water (in between) and a mineral surface (bottom). It is shown that the thickness or number of mono-layers of the interfacial water depends on temperature and atmospheric relative humidity. The maximum value of mono-layers is reached directly below the frost point temperature. The derived equations for the sandwich model fit well to a known phenomenological relation between thickness of the liquid layer and relative humidity. The curvature of grain surfaces is shown to have no remarkable effects for particles in the µm-range and larger. The freezing point depression for van der Waals force governed interfacial water is shown to depend on the value of the Hamaker constant, on the latent heat of solidification, on the mass density of water ice, and on the thickness of the liquid layer. This relation fits well to a known phenomenological relation between freezing point depression and thickness of the liquid layer. The derived equation shows that the lower limiting temperature of the liquid phase reaches about 180 K under martian conditions having an atmospheric water content of around 10 pr µm. Furthermore, an "Equilibrium moisture content" (EMC)/"Equilibrium Relative Humidity" (ERH) relation for the water content of martian soil has been derived, which relates, for equilibrium conditions, soil water content and atmospheric relative humidity. This relation indicates that the content of liquid interfacial water in the upper surface of Mars can reach up to 10% by weight and more in course of saturation during night hours, and it can be of about 2 % by weight during the dry daytime hours. The application of the results of the sandwich-model to thermo-physical conditions on Mars shows that the thickness of frost-layers, which can evolve over several hours on cooling surface parts of Mars, is for low latitudes typically of the order or a few tenths of one millimetre or less. This is in agreement with observations. Physical, as rheological, and chemical, as photo-catalytic, and hypothetical biological consequences of the presence of undercooled liquid interfacial water in the upper martian surface are discussed.

Möhlmann, Diedrich

125

Redox potential of liquid water: A first-principles theory  

NASA Astrophysics Data System (ADS)

A first-principles molecular dynamic method is proposed to calculate the absolute redox potentials of liquid water. The key of the method is the evaluation of the difference between the vacuum level and the average electrostatic potential inside liquid water, which employs an average over both time and space. By avoiding the explicit use of the Kohn-Sham level, such as the position of the valence band maximum, as the reference energy for the excited electrons, we are able to calculate water redox potentials accurately. The results using the PBE functional are in good agreement with experiment. We attribute the success of the method to the accurate charge density given by density functional calculation under the local or semi-local approximations. This establishes the validity to apply these effective and efficient approximations to study both the energetics and dynamics of the redox processes at more complex systems such as solid/solution interfaces.

Lucking, Michael; Sun, Yiyang; West, Damien; Zhang, Shengbai

2013-03-01

126

Entropy of liquid water from ab initio molecular dynamics.  

PubMed

We have computed the entropy of liquid water using a two-phase thermodynamic model and trajectories generated by ab initio molecular dynamics simulations. We present the results obtained with semilocal, hybrid, and van der Waals density functionals. 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. The underestimate is more severe for the PBE and PBE0 functionals than for several van der Waals functionals. PMID:21961845

Zhang, Cui; Spanu, Leonardo; Galli, Giulia

2011-09-30

127

Ionic liquid-based dispersive liquid-liquid microextraction for sensitive determination of aromatic amines in environmental water.  

PubMed

Ionic liquid-based dispersive liquid-liquid microextraction was developed for the extraction and preconcentration of aromatic amine from environmental water. A suitable mixture of extraction solvent (100 ?L, 1-butyl-3-methylimidazolium hexafluorophoshate) and dispersive solvent (750 ?L, methanol) were injected into the aqueous samples (10.00 mL), forming a cloudy solution. After centrifuging, enriched analytes in the sediment phase were determined by HPLC-UV. The effect of various factors, such as the extraction and dispersive solvent, sample pH, extraction time and salt effect were investigated. Under optimum conditions, enrichment factors for 2-anilinoethanol, o-chloroaniline and 4-bromo-N,N-dimethylaniline were above 50 and the limits of detection (LODs) were 0.023, 0.015 and 0.026 ng/mL, respectively. Their linear ranges were 0.8-400 ng/mL for 2-anilinoethanol, 0.5-200 ng/mL for o-chloroaniline and 0.4-200 ng/mL for 4-bromo-N,N-dimethylaniline, respectively. Relative standard deviations (RSDs) were below 5.0%. The relative recoveries from samples of environmental water were in the range of 82.0-94.0%. Compared with other methods, dispersive liquid-liquid microextraction is simple, rapid, sensitive and economical. PMID:21462339

Han, Dandan; Yan, Hongyuan; Row, Kyung H

2011-04-01

128

Interplay between Microscopic Diffusion and Local Structure of Liquid Water  

SciTech Connect

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

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

2010-11-29

129

Liquid water transport in polylactide homo and graft copolymers.  

PubMed

The successful design of new biodegradable, renewable resource plastics as replacements to commodity barrier plastics would benefit from an accurate measurement of sorption and diffusion of liquids. In this study, the diffusion of liquid water in amorphous polylactide [PLA] and a PLA graft copolymer, poly(1,5-cyclooctadiene-co-5-norbornene-2-methanol-graft-dl-lactide) [PCNL], was examined with time-resolved Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy. Non-Fickian behavior was observed for all experiments, indicated by a slow approach to steady state due to diffusion and polymer relaxation occurring on similar time scales. This non-Fickian behavior highlights the variability of the sorption isotherms reported in the literature, where others have collected nonequilibrium sorption behavior (instead of true steady-state equilibrium sorption) at different time points and film thicknesses. The dynamic infrared data provided direct evidence for both water diffusion and water-induced polymer relaxation, where both were quantified and regressed to a diffusion-relaxation model to determine the diffusion coefficient and the polymer relaxation time constant. In addition to the successful measurement and modeling of the diffusion-relaxation phenomena for diffusion of a liquid in a nonequilibrium state glassy polymer, this study also determined that the diffusivity of water in the PLA graft copolymer (with only 5 wt % rubber) was 3-fold lower than in the PLA homopolymer. PMID:21888318

Davis, Eric M; Theryo, Grayce; Hillmyer, Marc A; Cairncross, Richard A; Elabd, Yossef A

2011-09-21

130

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

131

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

132

Liquid water transport in fuel cell gas diffusion layers  

NASA Astrophysics Data System (ADS)

Liquid water management has a major impact on the performance and durability of the polymer electrolyte membrane fuel cell (PEMFC). The gas diffusion layer (GDL) of a PEMFC provides pathways for mass, heat, and electronic transport to and from the catalyst layers and bipolar plates. When the GDL becomes flooded with liquid water, the PEMFC undergoes mass transport losses that can lead to decreased performance and durability. The work presented in this thesis includes contributions that provide insight into liquid water transport behaviour in and on the surface of the GDL, as well as insight into how future GDLs could be designed to enhance water management. The effects of compression on liquid water transport in the GDL and on the microstructure of the GDL are presented. It was found that compressed regions of the GDL provided preferential locations for water breakthrough, while scanning electron microscopy (SEM) imaging revealed irreversible damage to the GDL due to compression at typical fuel cell assembly pressures. The dynamic behaviour of droplet emergence and detachment in a simulated gas flow channel are also presented. It was found that on an initially dry and hydrophobic GDL, small droplets emerged and detached quickly from the GDL surface. However, over time, this water transport regime transitioned into that of slug formation and channel flooding. It was observed that after being exposed to a saturated environment, the GDL surface became increasingly prone to droplet pinning, which ultimately hindered droplet detachment and encouraged slug formation. A pore network model featuring invasion percolation with trapping was employed to evaluate the breakthrough pattern predictions of designed porous media. These designed pore networks consisted of randomized porous media with applied diagonal and radial gradients. Experimental microfluidic pore networks provided validation for the designed networks. Diagonal biasing provided a means of directing water transport in the pore network, while radially biased networks provided the additional feature of reducing the overall network saturation. Since directed water transport and reduced saturation are both beneficial for the PEMFC GDL, it was proposed that biasing of this nature could be applied to improved GDL designs. Lastly, recommendations for future extensions of this research are proposed at the end of this thesis.

Bazylak, Aimy Ming Jii

133

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

134

30 CFR 250.248 - What solid and liquid wastes and discharges information and cooling water intake information must...  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

135

30 CFR 250.248 - What solid and liquid wastes and discharges information and cooling water intake information must...  

Code of Federal Regulations, 2010 CFR

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

2009-07-01

136

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

Code of Federal Regulations, 2010 CFR

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

2009-07-01

137

X-Ray Spectroscopy of the Liquid Water Surface  

NASA Astrophysics Data System (ADS)

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 liquid microjets, which have been characterized independently by Raman spectroscopy. Detection of ions and electrons produced by the Auger avalanche probe the bulk and surface regions of the microjet, respectively, as a result of their different escape depths. Our first efforts involved a comparative study of the interfaces of water and methanol, wherein we detailed the first observation of surface relaxation for a liquid. Analysis of EXAFS data yielded a 6distance at the water interface, whereas a 5was found for methanol. NEXAFS measurements, interpreted in terms of density functional theory simulations, indicate a large population of interfacial water molecules having two free OH bonds ("acceptor only molecules"). This complements the "single donor" species identified in sum frequency generation experiments. These results are supported by recent theoretical calculations. For methanol and other simple alcohols, the data indicate that free alkyl groups extend into the vapor part of the interface. Preliminary results for aqueous solutions, as well as for other pure liquids, have been obtained and are presently under analysis. REFERENCES 1. K.R. Wilson, R.D. Schaller, B.S. Rude, T. Catalano, D.T. Co, J.D. Bozek, and R.J. Saykally, "Surface relaxation in liquid water and methanol studied by X-ray absorption spectroscopy," J. Chem. Phys 117,7738(2002). 2. K.R. Wilson, M. Cavalleri, B.S. Rude, R.D. Schaller, A. Nilsson, L.G.M. Pettersson, N. Goldman, T. Catalano, J.D. Bozek, and R.J. Saykally, "Characterization of hydrogen bond acceptor molecules at the water surface using near-edge x-ray absorption fine-structure spectroscopy and density functional theory," J. Phys.: Condens. Matter 14, L221-L226 (2002).

Saykally, Richard

2004-03-01

138

Phase transitions induced by nanoconfinement in liquid water.  

PubMed

We present results from molecular dynamics simulations of water confined by two parallel atomically detailed hydrophobic walls. Simulations are performed at T = 300 K and wall-wall separation d = 0.6-1.6 nm. At 0.7 < or = d < or = 0.9 nm, a first order transition occurs between a bilayer liquid (BL) and a trilayer heterogeneous fluid (THF) as water density increases. The THF is characterized by a liquid (central) layer and two crystal-like layers next to the walls. The BL-THF transition involves freezing of the two surface layers in contact with the walls. At d = 0.6 nm, the THF transforms into a bilayer ice (BI) upon decompression. Both the BL-THF and BI-THF transitions are induced by the surface regular atomic-scale structure. PMID:19257497

Giovambattista, Nicolas; Rossky, Peter J; Debenedetti, Pablo G

2009-02-06

139

Phase Transitions Induced by Nanoconfinement in Liquid Water  

NASA Astrophysics Data System (ADS)

We present results from molecular dynamics simulations of water confined by two parallel atomically detailed hydrophobic walls. Simulations are performed at T=300K and wall-wall separation d=0.6-1.6nm. At 0.7?d?0.9nm, a first order transition occurs between a bilayer liquid (BL) and a trilayer heterogeneous fluid (THF) as water density increases. The THF is characterized by a liquid (central) layer and two crystal-like layers next to the walls. The BL-THF transition involves freezing of the two surface layers in contact with the walls. At d=0.6nm, the THF transforms into a bilayer ice (BI) upon decompression. Both the BL-THF and BI-THF transitions are induced by the surface regular atomic-scale structure.

Giovambattista, Nicolas; Rossky, Peter J.; Debenedetti, Pablo G.

2009-02-01

140

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

141

Fractionation of sugar cane with hot, compressed, liquid water  

Microsoft Academic Search

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%),

Stephen Glen Allen; Lance Cameron Kam; Andreas Joseph Zemann; Michael Jerry Antal

1996-01-01

142

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

Microsoft Academic Search

An experimental investigation of the combustion characteristics of nanoaluminum (nAl), liquid water (H2O(l)), and hydrogen peroxide (H2O2) mixtures has been conducted. Linear and mass-burning rates as functions of pressure, equivalence ratio (?), and concentration of H2O2 in H2O(l) oxidizing solution are reported. Steady-state burning rates were obtained at room temperature using a windowed pressure vessel over an initial pressure range

J. L. Sabourin; G. A. Risha; R. A. Yetter; S. F. Son; B. C. Tappan

2008-01-01

143

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

Microsoft Academic Search

An experimental investigation of the combustion characteristics of nanoaluminum (nAl), liquid water (HO{sub (l)}), and hydrogen peroxide (HO) mixtures has been conducted. Linear and mass-burning rates as functions of pressure, equivalence ratio (), and concentration of HO in HO{sub (l)} oxidizing solution are reported. Steady-state burning rates were obtained at room temperature using a windowed pressure vessel over an initial

J. L. Sabourin; R. A. Yetter; G. A. Risha; S. F. Son; B. C. Tappan

2008-01-01

144

Electron inelastic-scattering cross sections in liquid water  

Microsoft Academic Search

Electron inelastic-scattering cross-section data for use as input in electron track-structure calculations in liquid water are re-examined and improved. The dielectric-response function used in such cross-sections is estimated on the basis of optical data and other experimental and theoretical information. The mean excitation energy for stopping power is obtained to be 81.8 eV, which is close to the recent experimental

Michael Dingfelder; Detlev Hantke; Mitio Inokuti; Herwig G. Paretzke

1999-01-01

145

Cloud Super-Cooled Liquid Water Estimation from Satellite Data  

NASA Astrophysics Data System (ADS)

An automated algorithm for estimating cloud super-cooled liquid water (SLW) from satellite data was developed to perform cloud surveys for assessing potential precipitation enhancement. The algorithm produces spatial cloud SLW column distributions by utilizing many of the Moderate Resolution Imaging Spectroradiometer (MODIS) derived cloud products in addition to parameterizations developed to estimate vertical cloud thickness and fractional cloud liquid water content. Vertically derived cloud SLW is integrated to produce column totals. Sensitivity studies identified differences up to 30% in SLW content from individual changes in the minimum cloud optical depth threshold, vertical cloud thickness estimation, moist adiabatic lapse rate, and cloud liquid fraction parameterization constants. Corrections to MODIS cloud water path artifacts also reduced the estimated SLW content by 10% to 50%. Validation of the cloud base height and temperature estimates and derived total column SLW has begun using ground data from the Atmospheric Radiation Measurement North Slope Alaska site and CloudSat radar derived cloud products. Results thus far indicate that the algorithm may underestimate important cloud properties such as cloud thickness and cloud liquid water content which, in turn, may lead to an underestimation of cloud SLW. Comparisons of the algorithm’s vertical estimates of cloud SLW to aircraft data taken during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in northern Alaska yield very good results. National Center for Environmental Prediction reanalysis data was sampled along with annual MODIS datasets in both dry and wet years over the state of New Mexico to identify specific environmental indicators. Although cloud coverage was similar between the two periods, cloud SLW was found to be 60% greater and the number of days in which the 500 mb level wind was predominantly westerly increased by 12% during the wet year. The parameters with the highest correlation to cloud SLW were the 700 mb to the 500 mb level relative humidity.

Roskovensky, J. K.; Ivey, M.; Porch, W.; Beavis, N.; Herrman, R.

2010-12-01

146

DGAT1, GH, GHR, PRL and PRLR polymorphism in water buffalo (Bubalus bubalis).  

PubMed

The polymorphism of several genes has been shown to affect the milk composition traits in dairy cattle, including DGAT1-exon8 K232A, GH-intron3 MspI, GH-exon5 AluI, GHR-exon8 F279Y, PRL-exon3 RsaI and PRLR-exon3 S18N. However, the polymorphism and effects of these genes on the milk traits of water buffalo are still unclear. In this study, four DNA pooling samples from Murrah, Nili-ravi, Murrah-Nili-Swamp crossbreed and Chinese swamp buffalo were constructed, respectively, and polymorphism of these sites was investigated using PCR-Single-strand conformation polymorphism and sequencing. Twenty-eight inter-specific single-nucleotide polymorphism (SNPs) were found in these six assayed gene fragments between buffalo and dairy cattle, including nine intra-specific SNPs among buffalo groups. All buffalo fixed a K allele genotype in DGAT1-exon8, MspI(+) restriction site(c nucleotide) and AluI(+) site(c nucleotide) at intron3 and exon5 of GH gene, F allele genotype of F279Y mutation in GHR gene, RsaI(-) restriction site at PRL-exon3/exon4 and N allele genotype of S18N mutation at PRLR-exon3. It provides an indirect evidence that water buffalo have fixed alleles with genotypes reported in dairy cattle, which is thought to be responsible for high milk fat, high protein content and low milk yield. Moreover, three new intra-specific SNPs were found including 275th?bp (c/t) in DGAT1 of Murrah buffalo, 109th?bp (t/a) in PRL-exon3/exon4 and 43rd?bp (c/t) in PRLR-exon3 of Chinese swamp buffalo. Information provided in this study will be useful in further studies to improve buffalo breeding for better lactation performances. PMID:21883511

Shi, D-S; Wang, J; Yang, Y; Lu, F-H; Li, X-P; Liu, Q-Y

2011-08-30

147

Computational studies of liquid water and diluted water in carbon tetrachloride  

SciTech Connect

Molecular dynamics simulations were carried out to study solvent effects on the energetic and dynamical properties of water molecules in liquid water and in carbon tetrachloride (CCl4). In these studies, the free energy profiles or potentials of mean force (PMF) for water dimers in both solvents were computed. The computed PMF results showed a stable minimum near 3 Å for the O-O separation, with a minimum free energy of about -2.8 kcal/mol in CCl4, as compared to a value of -0.5 kcal/mol in liquid water. The difference in free energy in water as compared to CCl4 was expected, and is the result of competition from surrounding water molecules, that are capable of forming hydrogen bonds) in the liquid water. This capability is absent in the diluted water found in CCl4. We found that the rotational motions were non-isotropic, with the out-of plane vector correlation times in water/D2O varying from 5.6/5.8 ps at 250 K to 0.57/0.56 ps at 350 K and the corresponding OH/OD bond vectors varying from 6.5/7.7 ps to 0.75/0.75 ps. The results compare reasonably well to the available NMR experimental and computer simulation data on the same system (Farrar and Skinner et al. JACS 2001, 123, 8047). For diluted water in CCl4, we found the computed rotational correlation times also were non-isotropic and much longer than the corresponding NMR experimental values at the same concentration (Farrar et al. J. Phys. Chem. A 2007, 111, 6146). Upon analyzing the water hydrogen bonding patterns as a function of water concentrations, we conclude that the differences in the rotational correlation times mainly result from the formation of water hydrogen-bonding networks as the water concentration is increased in liquid CCl4. In addition, we found the rotational correlation times to be substantially faster in liquid CCl4 than in liquid water. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.

Chang, Tsun-Mei; Dang, Liem X.

2008-02-21

148

Structural Relaxation in Liquid Water by Inelastic UV Scattering  

NASA Astrophysics Data System (ADS)

Using the novel synchrotron radiation based inelastic ultraviolet scattering technique, the dynamic structure factor of normal and supercooled liquid water has been measured at a momentum transfer Q?0.1 nm-1, in the temperature range 260 340K. The structural (?) relaxation has been observed in the supercooled temperature region (T?273 K), where the inverse relaxation time matches the frequency of the probed sound modes. The T dependence of the relaxation time shows a diverging behavior with a critical temperature T?220 K. These results provide a unique experimental opportunity to frame the dynamics of water in the mode-coupling theory.

Masciovecchio, C.; Santucci, S. C.; Gessini, A.; di Fonzo, S.; Ruocco, G.; Sette, F.

2004-06-01

149

Reaction of water vapor and oxygen with liquid uranium  

SciTech Connect

The reactions of water vapor and oxygen with liquid uranium were studied by modulated molecular-beam mass spectrometric methods. Equivalent pressures of the reactant fluxes on the surface ranged from 6 x 10/sup -6/ to 2 x 10/sup -4/ torr. Temperatures up to 1570 K were investigated. The metal surface was kept clean during reaction by mechanical removal of the oxide formed with a tungsten needle. For the clean liquid uranium surface, a water reaction probability of approx. 0.4 was deduced both from measurement of the reaction-product hydrogen signal and by the temperature dependence of the scattered reactant signal. Based solely on the latter measure, a reaction probability of 0.6 was estimated for oxygen. The reaction probabilities on the clean surface were temperature-independent. They decreased as the coverage of the surface by islands of oxide increased and, for water, appeared to approach a value of 0.08 for a surface completely covered with an oxide estimated to be 500 A thick. Bombardment of the surface during reaction with argon ions produced an increase in the reactivity on solid uranium but had a negligible effect on the reaction probability for the liquid.

Balooch, M.; Orlander, D.R.; Siekhaus, W.J.

1987-10-01

150

Liquid Water and Thermal Activity of Enceladus' South Polar Terrain  

NASA Astrophysics Data System (ADS)

The endogenic activity on Enceladus is only located on a specific region at the south pole, from which jets of water vapor and ice particles have been observed. Heat power required to sustain such an activity over geologic timescales remains problematic. In a recent study, we show that only interior models with a liquid water layer at depth can explain the observed magnitude of dissipation and its particular location at the south pole (Tobie et al., Icarus, 2008). Here, we investigate the thermal stability of a localized liquid water reservoir at the rock-ice interface by performing simulations of thermal convection in three-dimensional spherical geometry. Preliminary results indicate that a total power ranging between 2.4 GW and 8 GW, comparable to the typical tidal dissipation value expected in the south polar region, is required to sustain a localized liquid zone. We are currently coupling our 3D viscoelastic tidal dissipation model to the 3D thermal convection code in order to precisely determine the associated tidal dissipation field. Preliminary results will be presented. In parallel, we investigate the likelihood of short resurfacing events by incorporating a self-lubricating, simple damage rheology using a 2D cartesian version of the code. When stress accumulation leads to the rupture of the lithosphere, a heat flow of about 200 mW.m-2, comparable to the values observed over the south pole, is observed during a relatively short period of time (< 500 kyr).

Besserer, J.; Tobie, G.; Choblet, G.; Cadek, O.; Sotin, C.

2008-12-01

151

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.

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

2011-01-01

152

Intraspecific Diversity of Vibrio vulnificus in Galveston Bay Water and Oysters as Determined by Randomly Amplified Polymorphic DNA PCR  

Microsoft Academic Search

Randomly amplified polymorphic DNA (RAPD) PCR was used to analyze the temporal and spatial intraspe- cific diversity of 208 Vibrio vulnificus strains isolated from Galveston Bay water and oysters at five different sites between June 2000 and June 2001. V. vulnificus was not detected during the winter months (December through February). The densities of V. vulnificus in water and oysters

Meilan Lin; Deborah A. Payne; John R. Schwarz

2003-01-01

153

Liquid densities, heat capacities, refractive index and excess quantities for {protic ionic liquids + water} binary system  

Microsoft Academic Search

Densities, ?, of aqueous solutions of the room temperature protic ionic liquid (PIL), pyrrolidinium nitrate are determined at the atmospheric pressure over the temperature range from (283.15 to 323.15)K and within the whole composition range. The molar isobaric heat capacities, Cp, and refractive index, nD, of {PIL+water} binary system are measured at 298.15K. The excess molar volumes VE, excess molar

Mérièm Anouti; Magaly Caillon-Caravanier; Yosra Dridi; Johan Jacquemin; Christopher Hardacre; Daniel Lemordant

2009-01-01

154

Role of Water Activity of Liquid in Controlling Evaporation Rate of Low-Viscosity Liquids  

Microsoft Academic Search

Viscosity of liquid is normally the most critical factor when operating an evaporator in an industrial process. This study shows that the dewatering capacity during evaporation for a low-viscosity peptone solution was reduced 40% for water activity (aw) = 0.8 and 80% for aw = 0.45. Designers of evaporators should be aware of this phenomenon if the aim is to get a high degree

Øistein Høstmark; Sigurd Teigland

2009-01-01

155

Effect of ionic liquids on (vapor + liquid) equilibrium behavior of (water + 2-methyl-2-propanol)  

Microsoft Academic Search

Isobaric T, x, y data were reported for ternary systems of {water+2-methyl-2-propanol (tert-butyl alcohol, TBA)+ionic liquid (IL)} at p=100kPa. When the mole fraction of TBA on IL-free basis was fixed at 0.95, measurements were performed at IL mass fractions from 0.6 down to 0.05, in a way of repeated synthesis. The vapor-phase compositions were obtained by analytical methods and the

Lianzhong Zhang; Bingbang Qiao; Yun Ge; Dongshun Deng; Jianbing Ji

2009-01-01

156

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

SciTech Connect

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

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

2004-05-25

157

Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons  

SciTech Connect

A Simplified augmented BACK equation of state has been developed for the description of gas-liquid-liquid equilibria in mixtures of water, light, gases, and hydrocarbons. The simplification facilitates application of the equation. In the Augmented BACK equation the polar pressure of water is the difference between two long expressions. One of these is the 26-term BACK equation written for the non-polar core of the water molecule, and the other is the Keeman steam table equation containing 55 equation constants. The complexity is compounded when derivation is made of the equation for fugacity, enthalpy and other thermodynamic quantities, leading to working equations that contain more than one hundred terms. The complexity presents a barrier to useful application. The new simplified equation has been extensively tested. Calculations with the Augmented BACK equation (before simplification) are described with example mixtures. Included are mixtures of water + light gases, water + hydrocarbons, and polar substances in general. Phase equilibrium, density, and enthalpy are calculated. 3 figs.

Chao, K.C.

1989-01-01

158

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

2012-04-02

159

Occurrence, liquid water content, and fraction of supercooled water clouds from combined CALIOP/IIR/MODIS measurements  

NASA Astrophysics Data System (ADS)

The CALIOP depolarization measurements, combined with backscatter intensity measurements, are effective in discriminating between water clouds and ice clouds. The same depolarization measurements can also be used for estimating liquid water content information. Using cloud temperature information from the collocated infrared imaging radiometer measurements and cloud water paths from collocated MODIS measurements, this study compiles global statistics of the occurrence frequency, liquid water content, liquid water path, and their temperature dependence. For clouds with temperatures between -40°C and 0°C, the liquid phase fractions and liquid water paths are significantly higher than the ones from previous studies using passive remote sensing measurements. At midlatitudes, the occurrence of liquid phase clouds at temperatures between -40°C and 0°C depends jointly on both cloud height and cloud temperature. At high latitudes, more than 95% of low-level clouds with temperatures between -40°C and 0°C are water clouds. Supercooled water clouds are mostly observed over ocean near the storm-track regions and high-latitude regions. Supercooled water clouds over land are observed in the Northern Hemisphere over Europe, East Asia, and North America, and these are the supercooled water clouds with highest liquid water contents. The liquid water content of all supercooled water clouds is characterized by a Gamma (?) distribution. The mode values of liquid water content are around 0.06 g/m3 and are independent of cloud temperature. For temperatures warmer than -15°C, mean value of the liquid water content is around 0.14 g/m3. As the temperature decreases, the mean cloud liquid water content also decreases. These results will benefit cloud models and cloud parameterizations used in climate models in improving their ice-phase microphysics parameterizations and the aviation hazard forecast.

Hu, Yongxiang; Rodier, Sharon; Xu, Kuan-Man; Sun, Wenbo; Huang, Jianping; Lin, Bing; Zhai, Pengwang; Josset, Damien

2010-01-01

160

Dye/water separation through supported liquid membrane extraction.  

PubMed

The separation of synthetic dye Rhodamine 6G (R6G) and water was investigated using blended organic liquids in a supported liquid membrane (SLM) extraction system. Liquid membrane (LM) components include octyl alcohol (OcOH) as the dye extractant and a polysiloxane liquid as the stabilizing agent. Initial permeation results revealed the suitability of poly (phenyl methyl) siloxane (PPMS) over poly (octyl methyl) siloxane as the blending agent. The most acceptable condition for dye extraction was determined at feed solution pH congruent with 1, wherein highest distribution coefficient, K(D) (OcOH/H(2)O)=18, was attained. Though permeability decreased at optimal blending condition of 1:1 (w/w) OcOH/PPMS, SLM longevity was exhibited with>98% LM retention after 15 h operation in contrast to pure OcOH SLM system (>60% LM loss). Equilibrium experiments reveal that dye extraction followed Langmuir adsorption principle. The dye transport was elucidated using mass transfer analysis wherein it showed a decrease in overall coefficient (k(o)) at increasing feed concentrations. This was a direct consequence of K(D) decline, which becomes more apparent at higher concentrations when SLM saturation point is approached. At varied hydrodynamic conditions, improved k(o) values were observed up to Re(omega)=10,000 when minimal variation in film resistance is attained. Beyond this condition, k(o) becomes independent from stirring rate effect nonetheless SLM stability is compromised due to shear-induced LM losses. PMID:20553932

Nisola, Grace M; Cho, Eulsaeng; Beltran, Arnel B; Han, Mideok; Kim, Younghee; Chung, Wook-Jin

2010-08-01

161

A Liquid Water Model That Explains the Variation of Surface Tension of Water with Temperaure  

NASA Astrophysics Data System (ADS)

A model is presented that explains the variation of surface tension of liquid water with temperature. The presence of non H-bonding H (NHB H) atoms (defining surface of assumed clusters) together with H-bonding atoms, is considered in this treatment. A good agreement between the experimental and computed values suggests the validity of this model. The change in the number of NHB H atoms and density account for the variation of surface tension with temperature. Previously, the same model was applied to explain the anomalous variation of density of liquid water with temperature [A. Khan et.al.: Chem. Phys. Lett. 266 (1997) 473].

Khan, Arshad; Khan, M. Rezwan; Khan, M. Ferdouse; Khanam, Fahima

2001-03-01

162

Liquid Polyamorphism: Some Unsolved Puzzles of Water in Bulk, Nanoconfined, and Biological Environments  

Microsoft Academic Search

We investigate the relation between changes in dynamic and thermodynamic anomalies arising from the presence of the liquid-liquid critical point in (i) Two models of water, TIP5P and ST2, which display a first order liquid-liquid phase transition at low temperatures; (ii) the Jagla model, a spherically symmetric two-scale potential known to possess a liquid-liquid critical point, in which the competition

H. E. Stanley; Pradeep Kumar; Giancarlo Franzese; Limei Xu; Zhenyu Yan; Marco G. Mazza; S.-H. Chen; F. Mallamace; S. V. Buldyrev

2008-01-01

163

Polymorphic behavior of some fully hydrogenated oils and their mixtures with liquid oil  

Microsoft Academic Search

Fully hydrogenated soybean oil, beef fat, rapeseed oil, a rapeseed, palm and soybean oil blend, cottonseed oil and palm oil\\u000a were characterized by fatty acid composition, glyceride carbon number and partial glyceride content, as well as melting and\\u000a crystallization properties. The latter were established by differential scanning calorimetry. Polymorphic behavior was analyzed\\u000a by X-ray diffraction of the products in the

L. deMan; J. M. deMan; B. Blackman

1989-01-01

164

Side-chain liquid crystalline polymer networks: exploiting nanoscale smectic polymorphism to design shape-memory polymers.  

PubMed

Herein, we investigate the influence of nanoscale smectic polymorphism within end-on fixed side-chain liquid crystalline polymer networks (SCLCNs) on macroscopic shape-memory and actuation properties. We have synthesized a series of SCLC-type linear (TP-n) and cross-linked random terpolymers (XL-TP-n) with varying length of flexible methylene spacers (n = 5, 10, and 15) between polynorbornene main-chain and cholesteryl ester side-chains. Thermal and mechanical analyses by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirm a glass transition (T(g)), a clearing temperature (T(cl)), and a network structure in the XL-TP-n. Detailed structural investigation conducted using wide-angle and small-angle X-ray scattering (WAXS and SAXS) at room temperature proves self-assembled smectic A (SmA) polymorphism of the XL-TP-n which evolves from non-interdigitated bilayer (SmA(2)) for n = 5 to mixed layers of monolayer-like highly interdigitated layer (SmA(1)) and SmA(2) for n = 10 and to SmA(1) for n = 15. In addition, TP10 at temperatures above 60 °C interestingly shows transformation of SmA structure from mixed layer (SmA(1) + SmA(2)) to interdigitated structure (SmA(d)). The SmA polymorphism developed in TP-n during shape-memory cycles (SMCs) significantly impacts the ultimate strain responses. A mechanism for the unique interdigitation-based thermostrictive behavior is proposed. More importantly, this new actuation mechanism observed in these XL-TP-n can be exploited to develop intelligent thermal actuators. PMID:21401122

Ahn, Suk-kyun; Deshmukh, Prashant; Gopinadhan, Manesh; Osuji, Chinedum O; Kasi, Rajeswari M

2011-03-23

165

Combustion of Liquid Fuels Spilled on Water. Prediction of Time to Start of Boilover  

Microsoft Academic Search

The combustion of a liquid fuel floating on water is a problem of interest because of its potential environmental and safety consequences. When a liquid fuel is burning under these conditions, the presence of the water may cause some particular effects due to heat transfer to the water. If the fuel layer is thin, heat losses to the water may

J. P. GARO; P. GILLARD; J. P. VANTELON; A. C. FERNANDEZ-PELLO

1999-01-01

166

Thermodynamic properties of liquid water from a polarizable intermolecular potential  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation results are reported for the pressure, isothermal pressure coefficient, thermal expansion coefficient, isothermal and adiabatic compressibilities, isobaric and isochoric heat capacities, Joule-Thomson coefficient and speed of sound of liquid water using a polarizable potential [Li et al., J. Chem. Phys. 127, 154509 (2007)]. These properties were obtained for a wide range of temperatures and pressures at a common liquid density using the treatment of Lustig [J. Chem. Phys. 100, 3048 (1994)] and Meier and Kabelac [J. Chem. Phys. 124, 064104 (2006)], whereby thermodynamic state variables are expressible in terms of phase-space functions determined directly from molecular dynamics simulations. Comparison with experimental data indicates that the polarizable potential can be used to predict most thermodynamic properties with a very good degree of accuracy.

Yigzawe, Tesfaye M.; Sadus, Richard J.

2013-01-01

167

Quaternary isobaric (vapor + liquid + liquid) equilibrium and (vapor + liquid) equilibrium for the system (water + ethanol + cyclohexane + heptane) at 101.3 kPa  

Microsoft Academic Search

Experimental isobaric (vapor+liquid+liquid) and (vapor+liquid) equilibrium data for the ternary system {water (1)+cyclohexane (2)+heptane (3)} and the quaternary system {water (1)+ethanol (2)+cyclohexane (3)+heptane (4)} were measured at 101.3kPa. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer was used to determine the VLLE. The results obtained show that the system does not present quaternary azeotropes. The point-by-point method by

Ana Pequenín; Juan Carlos Asensi; Vicente Gomis

2011-01-01

168

Liquid water and resurfacing of Enceladus' south polar terrain  

NASA Astrophysics Data System (ADS)

Enceladus are the only solid objects in the Solar System to be sufficiently geologically active for their internal heat to be detected by remote sensing. Interestingly, the endogenic activity on Enceladus is only located on a specific region at the south pole, from which jets of water vapor and ice particles have been observed ([1], [2]). The current polar location of the thermal anomaly can possibly be explained by diapirinduced reorientation of the satellite [3], but the triggering of the thermal anomaly and the heat power required to sustain it over geologic timescales remain problematic. Using a three-dimensional viscoelastic numerical model simulating the response of Enceladus to tidal forcing, we have demonstrated in a previous recent study [4] that only interior models with a liquid water layer at depth can explain the observed magnitude of dissipation and its particular location at the south pole (Fig. 1). Moreover, as tidally-induced heat must be generated over a relatively broad region in the southern hemisphere to explain the observed thermal emission, we proposed that this heat is then transferred toward the south polar terrain where it could be episodically released during relatively short resurfacing events. In the present study, we investigate the thermal stability of localized liquid water reservoir at the rock-ice interface by performing simulations of thermal convection in three-dimensional spherical geometry with the numerical tool OEDIPUS ([5],[6]) and by computing the corresponding dissipation pattern using the method developped in [4]. Where liquid water is present, a constant temperature equal to the melting temperature of water ice is prescribed at the base of the ice shell. Outside this region, a constant heat flux owing to the radiogenic power coming out of the silicate core is prescribed. Figure 2 illustrates the temperature field obtained for varying size of the liquid reservoir (ranging from 60o to 120o). These preliminary results indicate that a total power of 2.4 GW is required to sustain a liquid zone of 60o in width, 5 GW for a liquid zone of 120o, and 8 GW for a liquid zone of 180o. This is comparable to the typical tidal dissipation value expected in the south polar region ([1], [4]). We are currently coupling our 3D viscoelastic tidal dissipation model to the 3D thermal convection code in order to precisely determine the tidal dissi- pation pattern resulting fromthe viscosity field and its effect on the 3D thermal structure. In parallel, we investigate the likelihood of short resurfacing events by incorporating a self-lubricating, simpledamage rheology adapted from [7] in our models in order to simulate the fracturation of the cold icy crust. As the 3D spherical simulations are extremely time-consuming,we perform this series of simulation using a 2D cartesian version of the code [8]. Two different evolution scenario are tested: a first one where the reservoir of liquid water is sufficiently large to be sustained during the entire duration of the simulation, a second one where the liquid water just disappeared at the beginning of the simulation. In the two scenarios, a rupture of the lithosphere is observed owing to stress accumulation near the surface. This leads to a short and huge release of heat. The preliminary simulation presented on Figure 3 indicates that heat flux of the order of 200 mW.m-2, comparable to the values observed over the south pole, are obtained during a relatively short period of time (< 500 kyr). This simulation shows that even if the liquid zone totally disappears and that tidal dissipation strongly decreases, a resurfacing event can still occur. However, the internal cooling associated with such an event is so large that only an initially large reservoir of liquids can survive. We are currently investigating the conditions in which a localized water sea can persist beneath the south pole on geologic timescales.

Tobie, G.; Besserer, J.; Cadek, O.; Choblet, G.; Sotin, C.

2008-09-01

169

Spectrophotometric determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction.  

PubMed

A simple method for the determination of mercury in water samples after preconcentration using dispersive liquid-liquid microextraction is described. The procedure is based on the extraction of mercury in the form of a complex and its subsequent determination by spectrophotometry. The complex is formed between Hg(II) and 2-(2-benzothiazolylazo)-p-cresol. The detection at 650 nm is performed directly in the metal-rich phase, which is spread on a triacetylcellulose membrane. The method eliminates the need to use a cuvet or large quantities of samples and reagents. The parameters that influence the preconcentration were studied, and the analytical characteristics were determined. The enrichment factor and the consumptive index for this method were 64 and 0.16 mL, respectively. The LOD (3.3 microg/L) and LOQ (11.1 microg/L) were also determined. The accuracy of the method was tested by the determination of mercury in certified reference materials BCR 397 (Human Hair) and SRM 2781 (Domestic Sludge). The method was applied to the determination of mercury in samples of drinking water, sea water, and river water. PMID:22468364

Lemos, Valfredo Azevedo; dos Santos, Liz Oliveira; Silva, Eldevan dos Santos; Vieira, Emanuel Vitor dos Santos

170

Molecular-dynamics simulation of liquid water with an ab initio flexible water-water interaction potential  

Microsoft Academic Search

The Matsuoka-Clementi-Yoshimine (MCY) configuration interaction potential for rigid water-water interactions has been extended to include the intramolecular vibrations. The extended potential (MCYL), using no empirical parameters other than the atomic masses, electron charge, and Planck constant, is used in a molecular-dynamics simulation study of the static and dynamic properties of liquid water. Among the properties studied are internal energy, heat

G. C. Lie; E. Clementi

1986-01-01

171

Effects of the dispersion interaction in liquid water  

NASA Astrophysics Data System (ADS)

The properties of liquid water obtained from molecular simulations using a density functional theory (B3LYP) based force field [O. Akin-Ojo, F. Wang, J. Comput. Chem. 32 (2011) 453.] with and without an intermolecular dispersion interaction term are compared. Although it is small, the dispersion interaction is found to significantly affect some properties such as the density and the heat of vaporization but not others, for example, the atom-atom radial distribution functions and the infrared spectra. The inclusion of the dispersion interaction in the force field produces an increase in the computed self diffusivity comparable to that resulting from a ˜5 K rise in temperature.

Akin-Ojo, Omololu; Wang, Feng

2011-09-01

172

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

SciTech Connect

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

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

1980-01-01

173

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.

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

2012-01-01

174

Detection of Subsurface Liquid Water Using Magnetotellurics on Mars  

NASA Astrophysics Data System (ADS)

The characterization of past or present water on Mars remains a core goal of the Mars exploration program, representing a cross-cutting theme that ties together investigations relevant to life, climate, geology, and the identification of sites for future exploratory landed missions. Passive, low frequency electromagnetic (EM) soundings of the subsurface can identify salinated liquid water at depths ranging from hundreds of meters to ~10 km in an environment such as Mars. Among the tools necessary to perform these soundings are low frequency electric and magnetic field sensors capable of being deployed from a lander or rover. With support from both the NASA Planetary Instrument Definition and Development Program (PIDDP) and Mars Instrument Development Program (MIDP), we are currently developing an autonomous sensor platform that can perform magnetotelluric soundings in environments such as Mars within the constraints of current lander or rover architectures. Once fully developed, this technique will represent both a complementary and alternative method to orbital radar sounding investigations, performing deep soundings at sites identified as high priority areas by orbital radars or detecting subsurface water in environments that render radar methods ineffective. In either case, the sensitivity and depth of penetration inherent in low-frequency EM exploration makes this tool a compelling candidate method to identify subsurface liquid water from a landed platform on Mars or other targets of interest. We will describe current results obtained with our prototype systems from various terrestrial field sites, discuss sources of passive EM energy on Mars, and how these measurements might be conducted on future missions.

Delory, G. T.; Grimm, R. E.; Nielsen, T.; Farrell, W. M.

2005-12-01

175

INSEDELF: method of studying separation in liquid–liquid phase application to water–diesel fuel emulsions  

Microsoft Academic Search

The use of the INSEDELF method to measure solid–liquid phase separation was extended to water\\/diesel fuel emulsions to study liquid–liquid phase separation. We have demonstrated that this method is a pertinent tool for characterising the stability of these emulsions and for optimising complex formulations intended for winter use of these fuels. It permitted determination of the optimal content of antifreeze

P Schulz; L Dalix; J. M Letoffe; Y Faure

2004-01-01

176

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

177

New water equivalent liquid scintillation solutions for 3D dosimetry.  

PubMed

Despite recent advances in radiochromic film and gel dosimetry techniques, radiation therapy still lacks an efficient, accurate, and convenient dose measurement method capable of measuring the dose simultaneously over a plane or a volume (3D). A possibility for creating such a 3D method based on observing scintillation photons emitted from an irradiated volume was recently reported [A. S. Kirov et al., Med. Phys. 26, 1069 (1999)]. In the present article, we investigate the potential to use a liquid scintillation solution (LS) as a dose sensitive media and, simultaneously, as a water equivalent phantom material which fills the measurement volume. We show that matching water density in addition to energy absorption properties is important for using the LS solution as a phantom. Through a parametric study of the LS attenuation and absorption coefficients as well as Monte Carlo dose calculations and scintillation efficiency measurements we developed novel LS materials. For the new solutions, the calculated dose in LS is within 8% of the dose to water for depths up to 5 cm for photons having energies between 30 keV and 2 MeV. The new LS solutions, which are loaded with a Si containing compound, retain more than 85% of the scintillation efficiency of the unloaded solutions and exhibit high localization of the scintillation process. The new LS solutions are superior with respect to efficiency and water equivalence to plastic scintillator materials used in dosimetry and may be used apart from the mentioned 3D method. PMID:10841423

Kirov, A S; Shrinivas, S; Hurlbut, C; Dempsey, J F; Binns, W R; Poblete, J L

2000-05-01

178

Liquid-vapor equilibrium isotopic fractionation of water: How well can classical water models predict it?  

Microsoft Academic Search

The liquid-vapor equilibrium isotopic fractionation of water is determined by molecular-based simulation, via Gibbs ensemble Monte Carlo and isothermal-isochoric molecular dynamics involving two radically different but realistic models, the extended simple point charge, and the Gaussian charge polarizable models. The predicted temperature dependence of the liquid-vapor equilibrium isotopic fractionation factors for H218O\\/H216O, H217O\\/H216O, and 2H1H16O\\/1H216O are compared against the most

Ariel A. Chialvo; Juske Horita

2009-01-01

179

Response functions near the liquid-liquid critical point of ST2 water  

NASA Astrophysics Data System (ADS)

We simulate the ST2 water model for time periods up to 1000 ns, and for four different system sizes, N = 63, 73, 83, and 93. We locate the liquid-liquid phase transition line and its critical point in the supercooled region. Near the liquidliquid phase transition line, we observe that the system continuously flips between the low-density and high-density liquid phases. We analyze the transition line further by calculating two thermodynamic response functions, the isobaric specific heat capacity CP and the isothermal compressibility KT. We use two different methods: (i) from fluctuations and (ii) with the relevant thermodynamic derivative. We find that, within the accuracy of our simulations, the maxima of two different response functions occur at the same temperatures. The lines of CP and KT maxima below the critical pressure approximate the Widom line which is continuous with the line of first-order transitions in the two-phase region where we observe the phase flipping.

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

2013-02-01

180

NOTE: Cryovolcanism and the Recent Flow of Liquid Water on Mars  

Microsoft Academic Search

The surface of Mars is too cold and dry to permit stable liquid water, yet fresh, apparently water-carved gullies and seepage features have been identified in high-resolution imaging of canyon and crater walls by the Mars Global Surveyor spacecraft. Here, a model of nonequilibrium hydrological activity and liquid water cryovolcanism explains the paradoxical appearance and observed properties of these landforms:

Eric J. Gaidos

2001-01-01

181

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

EPA Science Inventory

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

182

(Liquid + liquid) equilibria of (water + propionic acid + dipropyl ether or diisopropyl ether) at T = 298.2 K  

Microsoft Academic Search

(Liquid+liquid) equilibrium (LLE) data for (water+propionic acid+dipropyl ether) and (water+propionic acid+diisopropyl ether) were measured at T=298.2K and atmospheric pressure. The tie-line data were correlated by means of the UNIQUAC equation, and compared with results predicted by the UNIFAC method. A comparison of the extracting capabilities of the solvents was made with respect to distribution coefficients, separation factors, and solvent free

Dilek Özmen

2007-01-01

183

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

184

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

185

Ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction followed high-performance liquid chromatography for the determination of ultraviolet filters in environmental water samples.  

PubMed

In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (IL-USA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and preconcentration of four benzophenone-type ultraviolet (UV) filters (viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from three different water matrices. The procedure was based on a ternary solvent system containing tiny droplets of ionic liquid (IL) in the sample solution formed by dissolving an appropriate amount of the IL extraction solvent 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]) in a small amount of water-miscible dispersive solvent (methanol). An ultrasound-assisted process was applied to accelerate the formation of the fine cloudy solution, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters that affected the extraction efficiency (such as type and volume of extraction and dispersive solvents, ionic strength, pH and extraction time) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 354-464, and good repeatability of the extractions (RSDs below 6.3%, n=5). The limits of detection were in the range of 0.2-5.0 ng mL(-1), depending on the analytes. The linearities were between 1 and 500 ng mL(-1) for BP, 5 and 500 ng mL(-1) for BP-3 and HMS and 10 and 500 ng mL(-1) for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in river, swimming pool and tap water samples and acceptable relative recoveries over the range of 71.0-118.0% were obtained. PMID:23062433

Zhang, Yufeng; Lee, Hian Kee

2012-04-20

186

Study on the liquid membrane oscillation of water\\/oil\\/water system containing TTAB and picric acid  

Microsoft Academic Search

The liquid membrane oscillation of a novel water (aqueous tetradecyl trimethyl ammoniumbromide, TTAB and alcohol solution)\\/oil (picric acid in chloroform solution)\\/water (aqueous glucose solution) system was investigated. By using homemade device, the curves of various liquid membranes oscillation with different concentration of TTAB and picric acid, types of alcohol and other organic solvents at different temperature were measured. The results

Li Zhou; Jiao Ning Tang; Bo Liu; Yi Guang Wu; Ai Lian Wang; Chuan Dong Liao

2008-01-01

187

Hydrogen bonds in liquid water are broken only fleetingly  

NASA Astrophysics Data System (ADS)

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. Author contributions: J.D.E., J.J.L., C.J.F., A.T., and P.L.G. designed research; J.D.E., J.J.L., C.J.F., and S.T.R. performed research; J.D.E., J.J.L., C.J.F., S.T.R., A.T., and P.L.G. analyzed data; and J.D.E., J.J.L., C.J.F., S.T.R., A.T., and P.L.G. wrote the paper.Abbreviations: HB, hydrogen-bonded configuration; NHB, nonhydrogen-bonded configuration; MD, molecular dynamics.†J.D.E. and J.J.L. contributed equally to this work.‡Present address: Department of Chemistry, Columbia University, New York, NY 10027.§Present address: Department of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853.

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

2005-09-01

188

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

189

Salt-assisted liquid–liquid microextraction with water-miscible organic solvents for the determination of carbonyl compounds by high-performance liquid chromatography  

Microsoft Academic Search

A simple and rapid method has been reported for the determination of carbonyl compounds involving reaction with 2,4-dinitrophenylhydrazine and extraction of hydrazones with water-miscible organic solvent acetonitrile when the phase separation occurs by addition of ammonium sulphate, a process called salt-assisted liquid–liquid microextraction. The extract was analyzed by high-performance liquid chromatography with UV detection at 360nm. The procedure has been

Manju Gupta; Archana Jain; Krishna K. Verma

2009-01-01

190

Determination of phthalate esters in bottled water using dispersive liquid–liquid microextraction coupled with GC-MS.  

PubMed

Dispersive liquid-liquid microextraction method was developed for the determination of the amount of phthalate esters in bottled drinking water samples and dispersive liquid-liquid microextraction samples were analyzed by GC-MS. Various experimental conditions influencing the extraction were optimized. Under the optimized conditions, very good linearity was observed for all analytes in a range between 0.05 and 150 ?g/L with coefficient of determination (R²) between 0.995 and 0.999. The LODs based on S/N = 3 were 0.005-0.22 ?g/L. The reproducibility of dispersive liquid-liquid microextraction was evaluated. The RSDs were 1.3-5.2% (n = 3). The concentrations of phthalates were determined in bottled samples available in half shell. To understand the leaching profile of these phthalates from bottled water, bottles were exposed to direct sunlight during summer (temperature from 34-57°C) and sampled at different intervals. Result showed that the proposed dispersive liquid-liquid microextraction is suitable for rapid determination of phthalates in bottled water and di-n-butyl, butyl benzyl, and bis-2-ethylhexyl phthalate compounds leaching from bottles up to 36 h. Thereafter, degradation of phthalates was observed. PMID:23936915

Mousa, Amayreh; Basheer, Chanbasha; Al-Arfaj, Abdul Rahman

2013-06-01

191

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

192

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

193

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

2011-03-22

194

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

195

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.

Bai, Jaeil; Zeng, Xiao Cheng

2012-01-01

196

Heterogeneity Effects in Optical Cloud Liquid Water Path Retrievals  

NASA Astrophysics Data System (ADS)

We investigated heterogeneity effects in plane-parallel optical cloud liquid water paths (CLWPs), comparing Moderate Resolution Imaging Spectroradiometer (MODIS) estimates with those from Advanced Microwave Scanning Radiometer (AMSR-E), which are less susceptible to such effects. Consistency of optical and microwave retrievals was analyzed in one year of observations as a function of scene heterogeneity and solar/view geometry using two different heterogeneity metrics, measuring either cloud top variability or horizontal liquid water variability. While both heterogeneity metrics showed similar geographical and seasonal variations, cloud top variability proved less effective in identifying scenes with significant 3D effects in quarter-degree domain mean CLWPs. Microwave and optical CLWPs showed consistently larger correlations and smaller rms differences for homogeneous than for heterogeneous scenes. Zonal means were in relatively good agreement in the summer hemisphere; however, in the winter hemisphere, MODIS CLWPs sharply increased toward the poles in contrast to AMSR-E. This discrepancy was mainly due to 3D effects in MODIS retrievals over heterogeneous scenes at large solar zenith angles. Microwave retrievals in all scenes, and optical retrievals in homogeneous scenes showed similar and small solar zenith angle dependence, and were remarkably consistent at all view directions. In heterogeneous scenes at low sun, however, MODIS CLWPs increased by 40% on average, and were also considerably larger for oblique views than for overhead views due to increased viewing of illuminated cloud sides. We note that the heterogeneity parameters themselves also exhibited similar U-shaped view angle dependence. The results presented may help create more consistent microwave and optical CLWP climatologies.

Horvath, A.; Chellappan, S.

2009-12-01

197

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

198

A Rapid Analysis of Surface Waters by High Pressure Liquid Chromatography.  

National Technical Information Service (NTIS)

A simple rapid method for obtaining fingerprint traces of nonpolar organic contaminants in water samples by trace enrichment and high pressure liquid chromatography (HPLC) has been evolved. Samples of 30-1000 ml of river water were filtered through precol...

K. Huibregtse

1979-01-01

199

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

200

Possible physical and thermodynamical evidence for liquid water at the Phoenix landing site  

Microsoft Academic Search

The objective of the Phoenix mission is to determine if Mars' polar region can support life. Since liquid water is a basic ingredient for life, as we know it, an important goal of the mission is to determine if liquid water exists at the landing site. It is believed that a layer of Martian soil preserves ice by forming a

Nilton O. Rennó; Brent J. Bos; David Catling; Benton C. Clark; Line Drube; David Fisher; Walter Goetz; Stubbe F. Hviid; Horst Uwe Keller; Jasper F. Kok; Samuel P. Kounaves; Kristoffer Leer; Mark Lemmon; Morten Bo Madsen; Wojciech J. Markiewicz; John Marshall; Christopher McKay; Manish Mehta; Miles Smith; M. P. Zorzano; Peter H. Smith; Carol Stoker; Suzanne M. M. Young

2009-01-01

201

Formation of Cyclic Water Hexamer in Liquid Helium: The Smallest Piece of Ice  

Microsoft Academic Search

The cyclic water hexamer, a higher energy isomer than the cage structure previously characterized in the gas phase, was formed in liquid helium droplets and studied with infrared spectroscopy. This isomer is formed selectively as a result of unique cluster growth processes in liquid helium. The experimental results indicate that the cyclic hexamer is formed by insertion of water molecules

K. Nauta; R. E. Miller

2000-01-01

202

Liquid Water Path and Plane-Parallel Albedo Bias during ASTEX  

Microsoft Academic Search

Inhomogeneous distributions of liquid water like those observed in real clouds generally reflect less solar radiation than idealized uniform distributions assumed in plane-parallel theory. Here the authors determine cloud reflectivity and the associated plane-parallel albedo bias from distributions of liquid water path derived from 28 days of microwave radiometer measurements obtained on Porto Santo Island in the Madeiras during June

Robert F. Cahalan; David Silberstein; Jack B. Snider

1995-01-01

203

Equilibrium structural model of liquid water: Evidence from heat capacity, spectra, density, and other properties  

Microsoft Academic Search

Hydrogen bond strength depends on both temperature and pressure. The gradient for hydrogen bond strength with temperature, or pressure, depends upon the hydrogen bonded structure. These features create an intimate connection between quantum mechanics and thermodynamics in the structure of liquid water. The equilibrium structural model of liquid water developed from analysis of the heat capacity at constant pressure is

Ralph C. Dougherty; Louis N. Howard

1998-01-01

204

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...

205

CFD Modeling of Gas-Liquid Flows in Water Electrolysis Units  

Microsoft Academic Search

This paper presents the results of computational fluid dynamics (CFD) modeling of gas - liquid flows in water electrolysis systems. CFD is used as a cost-effective design tool at Stuart Energy Systems Corporation (SESC) to opti mize the performance of different water electrolysis units produced by SESC. General-purpose CFD software is used as a framework for analyzing the gas -liquid

Vladimir AGRANAT; Andrei TCHOUVELEV

206

Relationship between molecular orientation and conductivity of dielectric liquids dissolving restrained water  

Microsoft Academic Search

The state of water clusters dissolved in dielectric liquids has been studied using an IR spectrum method. Especially, the effect of water clusters on electrical conductivity is measured together with temperature dependence. In this experiment, dielectric liquids, such as nitrobenzene, benzonitrile and methylbenzoate, which are connected to an electron acceptor base, are used. From the results, it is found that

K. Ota; S. Itahashi; Y. Hayashi; M. Sone; H. Mitsui; Y. Murooka

1999-01-01

207

Monte Carlo Simulation of Liquid Water and an Evaluation of Thermodynamic Properties  

Microsoft Academic Search

Monte Carlo simulations were performed on liquid water using a new intermolecular potential function. For the evaluation of the thermodynamic properties of liquid water, simple expressions were proposed for the energies and the partition function, which reproduces the results of simulations reasonably. Various thermodynamic properties including heat capacities and compressibility were obtained from the partition function. The anomalous properties of

Kazuhiko Honda; Kazuo Kitaura; Kichisuke Nishimoto

1991-01-01

208

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

Microsoft Academic Search

We are developing Aquarius, a multipurpose ice and liquid water isotope analyzer. Aquarius combines a liquid-to-gas converter with a laser spectrometer to measure water isotopologue abundances with per mil accuracy. Its compact size will be ideal for field hydrology, while an optional interface with a thermal ice drill will enable in situ measurement of polar climate records. Upon completion, Aquarius

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

2008-01-01

209

(Vapour + liquid) equilibrium of (DIPE + IPA + water) at 101.32 kPa  

Microsoft Academic Search

Thermodynamically consistent (vapour+liquid) equilibrium data at 101.32kPa have been determined for (diisopropyl ether+isopropyl alcohol+water) and its constituents (diisopropyl ether+isopropyl alcohol) and (isopropyl alcohol+water). The NRTL and UNIQUAC equations for the liquid phase activity coefficients were found to correlate better the experimental data. The ASOG and the original and modified UNIFAC group-contribution methods did not represent adequately the (vapour+liquid) equilibrium data

Alberto Arce; José Mart??nez-Ageitos; Eva Rodil; Ana Soto

2003-01-01

210

Vapor–liquid–liquid equilibrium and vapor–liquid equilibrium for the quaternary system water–ethanol–cyclohexane–toluene and the ternary system water–cyclohexane–toluene. Isobaric experimental determination at 101.3 kPa  

Microsoft Academic Search

Experimental isobaric vapor–liquid–liquid and vapor–liquid equilibrium data for the ternary system water (1)–cyclohexane (2)–toluene (3) and the quaternary system water (1)–ethanol (2)–cyclohexane (3)–toluene (4) were measured at 101.3kPa. An all-glass, dynamic recirculating still equipped with an ultrasonic homogenizer was used to determine the VLLE. The results obtained show that the system does not present quaternary azeotropes. The point-by-point method by

Ana Pequenín; Juan Carlos Asensi; Vicente Gomis

2011-01-01

211

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

PubMed Central

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

2013-01-01

212

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

213

Non-porous membrane-assisted liquid–liquid extraction of UV filter compounds from water samples  

Microsoft Academic Search

A method for the determination of nine UV filter compounds [benzophenone-3 (BP-3), isoamyl methoxycinnamate, 4-methylbenzylidene camphor, octocrylene (OC), butyl methoxydibenzoylmethane, ethylhexyl dimethyl p-aminobenzoate (OD-PABA), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate and homosalate] in water samples was developed and evaluated. The procedure includes non-porous membrane-assisted liquid–liquid extraction (MALLE) and LC–atmospheric pressure photoionisation (APPI)–MS\\/MS. Membrane bags made of different polymeric materials were examined

Rosario Rodil; Steffi Schrader; Monika Moeder

2009-01-01

214

Liquid–liquid phase separation in a ternary system of segmented polyetherurethane\\/dimethylformamide\\/water: effect of hard segment content  

Microsoft Academic Search

A series of segmented polyurethanes (SPUs) using poly(tetramethylene oxide) (PTMO), 4,4?-methylenebis (phenyl isocyanate) (MDI), and ethylene glycol (EG) with different molar ratios of MDI and PTMO were prepared to study the effects of the hard segment content in SPU on liquid–liquid phase separation in the SPU\\/dimethylformamide(DMF)\\/water system. The cloud points were obtained by a titration method and the phase diagrams

H. K Lee; J. Y Kim; Y. D Kim; J. Y Shin; S. C Kim

2001-01-01

215

Analysis of water in liquid and solid samples by headspace gas chromatography  

Microsoft Academic Search

Equilibrium headspace gas chromatography is applied for the analysis of water in liquid and solid samples which are first dissolved in a water miscible solvent. The preferred quantitation technique is the method of standard addition. A particular problem is the water blank, caused by the humidity of the enclosed air in the headspace vial and by the residual water content

B. Kolb; M. Auer

1990-01-01

216

Elucidating through-plane liquid water profile in a polymer electrolyte membrane fuel cell.  

SciTech Connect

In this paper, a numerical model incorporating micro-porous layers (MPLs) is presented for simulating water transport within the gas diffusion layers (GDLs) and MPLs as well as across their interfaces in a polymer electrolyte membrane (PEM) fuel cell. One-dimensional analysis is conducted to investigate the impacts of MPL and GDL properties on the liquid-water profile across the anode GDL-MPL and cathode MPL-GDL regions. Furthermore, two-dimensional numerical simulations that take MPLs into account are also carried out to elucidate liquid water transport, particularly through-plane liquid-water profile in a PEM fuel cell. Results from case studies are presented.

Wang, Yun (University of California, Irvine, CA); Chen, Ken Shuang

2010-10-01

217

Cloud Liquid Water Content Variability over the Indian Region  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

218

Routine use of PCR-restriction fragment length polymorphism analysis for identification of mycobacteria growing in liquid media.  

PubMed Central

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 produced restriction patterns not included in the PCR-RFLP algorithm and could therefore not be assigned to a species. These isolates were characterized by their morphologic and biochemical characteristics. Two of the isolates were identified as M. terrae complex and M. gordonae. The third isolate could not be definitively identified and could only be characterized as a Mycobacterium sp. most closely resembling M. chelonae. PCR-RFLP identifications agreed with the conventional identifications for 96 of the 100 isolates identified by PCR-RFLP. Subsequent identification of the four discordant isolates by gas chromatography analysis supported the PCR-RFLP identification of each isolate. Amplification products were also obtained from isolates of Streptococcus albus and Rhodococcus equi recovered from patient specimens; however, the restriction patterns of these nonmycobacterial species did not resemble the patterns of any mycobacterial species included in the PCR-RFLP algorithm. PCR-RFLP seems to be a reliable procedure for the routine identification of mycobacteria and has the potential for providing identifications of mycobacterial isolates which are more accurate than conventional identification techniques based on morphologic and biochemical characteristics.

Taylor, T B; Patterson, C; Hale, Y; Safranek, W W

1997-01-01

219

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

NASA Astrophysics Data System (ADS)

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

de, Dilip; Aziz de, Abdul

2012-10-01

220

Habitable Zone of Land Planets; 1-D EBM with t Transportation of Surface Liquid Water  

NASA Astrophysics Data System (ADS)

Abe et al. (2011) investigated climates on planets with a very small amount of water on their surface (called ‘land planets’). The notable feature of land planets is local balance between precipitation and evaporation. They, using GCM (General Circulation Model), have shown that liquid water is localized on high latitudes, while low latitudes are dried up. As a result, the value for incoming radiation by which liquid water on a land planet is completely evaporated (called the ‘complete evaporation limit’) corresponds to 170% of the incident solar flux that the present earth receives, which is substantially larger than that of a planet that is globally covered with ocean (122%, Nakajima et al. (1992)). The key for land planets to have large value for complete evaporation limit is the localization of liquid water on high latitudes. Their GCM, however, does not include transportation of liquid water on surface, which may disturb water localization. In order to investigate the influence of transportation of surface water on the complete evaporation limit for land planets, we develop the 1-D EBM (Energy Balance Model) including transportation of surface liquid water, which is given in forms of diffusion. As a result, we find that the complete evaporation limit is 122% of the incident solar flux when liquid water on planetary surface is transported very efficiently (one tenth as efficient as water vapor transportation in the atmosphere). This value is the same one as the complete evaporation limit for planets globally covered with ocean. On the other hand, when liquid water on the surface is not transported so efficiently (one five hundreds as efficient as water vapor transportation), water localization takes place and the complete evaporation limit of our model is about 140-150% of the incident solar flux, depending on the water content of the planet.

Takao, Yuya; Genda, H.; Kodama, T.; Abe, Y.

2011-09-01

221

Vapor-liquid equilibria of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems  

Microsoft Academic Search

Vapor-liquid equilibrium data of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems were measured at 60, 160, 300, and 760 mmHg at temperatures ranging from 315 to 488 K. The apparatus used in this work is a modified still especially designed for the measurement of low-pressure VLE, in which both liquid and vapor are continuously recirculated.

S. Y. Mun; Huen Lee

1999-01-01

222

Solidification of Liquid Concentrate and Solid Waste Generated as by-Products of the Liquid Radwaste Treatment Systems in Light-Water Reactors.  

National Technical Information Service (NTIS)

The treatment of liquid concentrate and solid waste produced in light-water reactors as by-products of liquid radwaste treatment systems consists of five basic operations: waste collection, waste pretreatment, solidification agent handling, mixing/packagi...

R. M. Neilson P. Colombo

1977-01-01

223

Evaluation of a Teflon Helix Liquid-Liquid Extractor for Concentration of Trace Organics from Water into Methylene Chloride (Journal Version).  

National Technical Information Service (NTIS)

A continuous liquid-liquid extraction system (CLLE) for concentrating trace organics from water into methylene chloride for analysis was designed, built and evaluated. The CLLE uses Teflon coils for phase contact and gravity phase separation. The system i...

R. J. Baker J. Gibs A. K. Meng I. H. Suffet

1987-01-01

224

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

225

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

226

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

Microsoft Academic Search

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

M. Pilar Peña; Ernesto Vercher; Antoni Martinez-Andreu

1996-01-01

227

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

NASA Astrophysics Data System (ADS)

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

Jayaraman, Saivenkataraman; Maginn, Edward J.

2007-12-01

228

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

PubMed

The melting point, enthalpy of fusion, and thermodynamic stability of two crystal polymorphs of the ionic liquid 1-n-butyl-3-methylimidazolium chloride are calculated using a thermodynamic integration-based atomistic simulation method. The computed melting point of the orthorhombic phase ranges from 365 to 369 K, depending on the classical force field used. This compares reasonably well with the experimental values, which range from 337 to 339 K. The computed enthalpy of fusion ranges from 19 to 29 kJ/mol, compared to the experimental values of 18.5-21.5 kJ/mol. Only one of the two force fields evaluated in this work yielded a stable monoclinic phase, despite the fact that both give accurate liquid state densities. The computed melting point of the monoclinic polymorph was found to be 373 K, which is somewhat higher than the experimental range of 318-340 K. The computed enthalpy of fusion was 23 kJ/mol, which is also higher than the experimental value of 9.3-14.5 kJ/mol. The simulations predict that the monoclinic form is more stable than the orthorhombic form at low temperature, in agreement with one set of experiments but in conflict with another. The difference in free energy between the two polymorphs is very small, due to the fact that a single trans-gauche conformational difference in an alkyl sidechain distinguishes the two structures. As a result, it is very difficult to construct simple classical force fields that are accurate enough to definitively predict which polymorph is most stable. A liquid phase analysis of the probability distribution of the dihedral angles in the alkyl chain indicates that less than half of the dihedral angles are in the gauche-trans configuration that is adopted in the orthorhombic crystal. The low melting point and glass forming tendency of this ionic liquid is likely due to the energy barrier for conversion of the remaining dihedral angles into the gauche-trans state. The simulation procedure used to perform the melting point calculations is an extension of the so-called pseudo-supercritical path sampling procedure. This study demonstrates that the method can be effectively applied to quite complex systems such as ionic liquids and that the appropriate choice of tethering potentials for a key step in the thermodynamic path can enable first order phase transitions to be avoided. PMID:18067361

Jayaraman, Saivenkataraman; Maginn, Edward J

2007-12-01

229

The effect of cyclohexene, a preservative in dichloromethane on the liquid-liquid extraction and analysis of chlorinated drinking water.  

PubMed

Liquid-liquid extraction with dichloromethane is the Environmental Protection Agency's (EPA) method of choice for the analysis of acid or base neutral organic chemicals in water. Free radical chlorination and oxidation products of cyclohexene (the solvent preservative) in dichloromethane have been observed in extracts of chlorinated drinking water (after 10(5) fold concentration) by gas chromatography and gas chromatography-mass spectrometry. The chlorinated cyclohexene derivatives limit the quantitative and qualitative analysis of compounds eluting at Kovát's index less than 700-1000 and the use of these extracts for organoleptic and mutagenic studies. The effect of residual free chlorine in water on the cyclohexene present in the solvent was studied. Over ten cyclohexene derivatives were produced in every case when any residual free chlorine was present in the water. When chlorine is reduced to chloramine, the cyclohexene derivatives were greatly reduced in number and amount. PMID:3597602

Ibrahim, E A; Lippincott, R L; Brenner, L; Suffet, I H; Hannah, R E

1987-04-29

230

Mesoscale modeling of the water liquid-vapor interface: A surface tension calculation  

NASA Astrophysics Data System (ADS)

We report a mesoscale modeling of the liquid-vapor interface of water. A mesoscopic model of water has been established in dissipative particle dynamics (DPD) to reproduce the interfacial properties of water. The surface tension and coexisting densities are compared between atomistic and mesoscopic simulations. Simple scaling relations have been established to link the atomistic and mesoscopic length and time scales. Our study demonstrates the capability of the DPD method to explore the interfacial properties of a planar water liquid-vapor interface and a water nanodroplet. This constitutes an important step toward the calculation of the surface tension of larger and more complex interfacial systems.

Ghoufi, A.; Malfreyt, P.

2011-05-01

231

Determination of true octanol-water partition coefficients by means of solvent generated liquid-liquid chromatography  

Microsoft Academic Search

Compared to other methods for the determination of octanol-water partition coefficients chromatography offers a number of advantages: sample purification is unnecessary, the partition coefficients of the components of a mixture can be measured simultaneously and a minimum amount of sample is needed. In the past these determinations were almost exclusively carried out by liquid-solid chromatography (LSC) on alkyl bonded silica

M. Cichna; P. Markl; J. F. K. Huber

1995-01-01

232

Mixturelike behavior near a liquid-liquid phase transition in simulations of supercooled water.  

PubMed

In simulations of a waterlike model (ST2) that exhibits a liquid-liquid phase transition, we test for the occurrence of a thermodynamic region in which the liquid can be modeled as a two-component mixture. We assign each molecule to one of two species based on the distance to its fifth-nearest neighbor, and evaluate the concentration of each species over a wide range of temperature and density. Our concentration data compare well with mixture-model predictions in a region between the liquid-liquid critical temperature and the temperature of maximum density. Fits of the model to the data in this region yield accurate estimates for the location of the critical point. We also show that the liquid outside the region of density anomalies is poorly modeled as a simple mixture. PMID:21469883

Cuthbertson, Megan J; Poole, Peter H

2011-03-17

233

Flash evaporation from a water pool: Influence of the liquid height and of the depressurization rate  

Microsoft Academic Search

This article presents a study about the influence of the initial water height and of the depressurization rate on the flash evaporation of a water film. Experimental study is carried out with initial water height ranging from 25 to 250 mm, superheats between 2 and 44 K, and an initial liquid temperature from 45 to 85?°C. Visualization of the phenomenon

D. Saury; S. Harmand; M. Siroux

2005-01-01

234

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

235

Determination of medroxyprogesterone in water samples using dispersive liquid-liquid microextraction with low solvent consumption  

Microsoft Academic Search

A simple, rapid and efficient extraction procedure, dispersive liquid-liquid microextraction with low solvent consumption,\\u000a has been developed in combination with high-performance liquid chromatography-ultraviolet detection for the extraction and\\u000a determination of medroxyprogesterone from aqueous samples. For this technique, 120 ?L of the mixture of extraction solvent\\u000a and dispersive solvent at a ratio of 3:7 was injected into the aqueous sample with a

Shaofei Xie; Bingren Xiang; Ming Zhang; Haishan Deng

2010-01-01

236

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

237

Liquid-liquid equilibria for ternary systems of dimethyl carbonate + C 1 ? C 4 alcohols + water at 298.15 K and atmospheric pressure  

Microsoft Academic Search

The ternary liquid-liquid equilibria (LLE) of the following systems were analytically determined at 298.15K and atmospheric pressure using stirred and thermo-regulated cells: {dimethyl carbonate (DMC)+methanol+water}, {DMC+ethanol+water}, {DMC+1-propanol+water}, {DMC+2-propanol+water}, {DMC+1-butanol+water} and {DMC+2-butanol+water}. The experimental ternary LLE data were correlated with the Non-Random Two Liquid (NRTL) and UNIversal QUAsiChemical (UNIQUAC) activity coefficient models. In addition, the Bachman-Brown correlation was used to ascertain

In-Chan Hwang; So-Jin Park; Kyu-Jin Han; Se-Jin In

238

Vapor–Liquid Equilibrium of Ethanol–Water System in the Presence of Molecular Sieves  

Microsoft Academic Search

Adsorptive distillation is a new process to separate liquid mixtures in a packed distillation column. It depends on using active packing material instead of inert packing material in a packed distillation column. The active packing material can affect the intermolecular forces among the system components and thus alter its vapor–liquid equilibrium (VLE). The VLE of the ethanol–water system at 1

FAHMI A. ABU AL-RUB; FAWZI A. BANAT; RAMI JUMAH

1999-01-01

239

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

NASA Astrophysics Data System (ADS)

Peculiarities of the behavior of water solutions of inorganic salts at temperatures of ˜(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.; Koryavko, N. A.; Chichikov, S. A.

2013-05-01

240

CFD MODELING OF GAS LIQUID FLOW AND HEAT TRANSFER IN A HIGH PRESSURE WATER ELECTROLYSIS SYSTEM  

Microsoft Academic Search

A high -pressure water electrolysis system has been investigated numerically and experimentally . The advanced CFD model of tw o-phase flow, which calculated the 3D distributions of pressure, gas and liquid velocities and gas and liquid volume fractions, has been developed to account for all the major components in the system, and appropriate constitutive equations for two -phase f low

V. Agranat; S. Zhubrin; A. Maria; J. Hinatsu; M. Stemp; M. Kawaji

241

Comparative study of electron energy deposition and yields in water in the liquid and vapor phases  

Microsoft Academic Search

Dual sets of Monte Carlo computations were made for electrons in water to assess differences due to the state of condensation. The GSF computer code was used for the vapor and the ORNL code for the liquid. The underlying physical differences specifically incorporated into the liquid code are discussed. At electron energies greater than or equal to 50 eV, ionization

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

1982-01-01

242

Water in nanopores: II. The liquid vapour phase transition near hydrophobic surfaces  

Microsoft Academic Search

The liquid-vapour phase transition near a weakly attractive surface is studied by simulations of the coexistence curves of water in hydrophobic pores. There is a pronounced gradual density depletion of the liquid phase near the surface without any trend to the formation of a vapour layer below the bulk critical temperature TC. The temperature dependence of the order parameter in

Ivan Brovchenko; Alfons Geiger; Alla Oleinikova

2004-01-01

243

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

EPA Science Inventory

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

244

Evaluation of the applicability of the model of incompressible liquid in the calculation of water hammer  

NASA Astrophysics Data System (ADS)

The article establishes the limits of applicability of the model of incompressible liquid for calculating water hammer. The time of closing the valve is determined at which periodic oscillations do not arise.

Rozenberg, G. D.; Leonov, E. G.

1983-04-01

245

Satellite retrieval of the liquid water fraction in tropical clouds between -20 and -38 °C  

NASA Astrophysics Data System (ADS)

This study describes a satellite remote sensing method for directly retrieving the liquid water fraction in mixed phase clouds, and appears unique in this respect. The method uses MODIS split-window channels for retrieving the liquid fraction from cold clouds where the liquid water fraction is less than 50% of the total condensate. This makes use of the observation that clouds only containing ice exhibit effective 12-to-11 ?m absorption optical thickness ratios (?eff) that are quasi-constant with retrieved cloud temperature T. This observation was made possible by using two CO2 channels to retrieve T and then using the 12 and 11 ?m channels to retrieve emissivities and ?eff. Thus for T < -40 °C, ?eff is constant, but for T > -40 °C, ?eff slowly increases due to the presence of liquid water, revealing mean liquid fractions of ~ 10% around -22 °C from tropical clouds identified as cirrus by the cloud mask. However, the uncertainties for these retrievals are large, and extensive in situ measurements are needed to refine and validate these retrievals. Such liquid levels are shown to reduce the cloud effective diameter De such that cloud optical thickness will increase by more than 50% for a given water path, relative to De corresponding to pure ice clouds. Such retrieval information is needed for validation of the cloud microphysics in climate models. Since low levels of liquid water can dominate cloud optical properties, tropical clouds between -25 and -20 °C may be susceptible to the first aerosol indirect effect.

Mitchell, D. L.; d'Entremont, R. P.

2012-07-01

246

Satellite retrieval of the liquid water fraction in tropical clouds between -20 and -38 °C  

NASA Astrophysics Data System (ADS)

This study describes a satellite remote sensing method for directly retrieving the liquid water fraction in mixed phase clouds, and appears unique in this respect. The method uses MODIS split-window channels for retrieving the liquid fraction from cold clouds where the liquid water fraction is less than 50% of the total condensate. This makes use of the observation that clouds only containing ice exhibit effective 12-to-11 ?m absorption optical thickness ratios (?eff) that are quasi-constant with retrieved cloud temperature T. This observation was made possible by using two CO2 channels to retrieve T and then using the 12 and 11 ?m channels to retrieve emissivities and ?eff. Thus for T < -40 °C, ?eff is constant, but for T > -40 °C, ?eff slowly increases due to the presence of liquid water, revealing mean liquid fractions of ~10% around -22 °C from tropical clouds identified as cirrus by the cloud mask. However, the uncertainties for these retrievals are large, and extensive in situ measurements are needed to refine and validate these retrievals. Such liquid levels are shown to reduce the cloud effective diameter De such that cloud optical thickness will increase by more than 50% for a given water path, relative to De corresponding to pure ice clouds. Such retrieval information is needed for validation of the cloud microphysics in climate models. Since low levels of liquid water can dominate cloud optical properties, tropical clouds between -25 and -20 °C may be susceptible to the first aerosol indirect effect.

Mitchell, D. L.; D'Entremont, R. P.

2011-12-01

247

Selection of ionic liquids as entrainers for separation of water and 2-propanol  

Microsoft Academic Search

A procedure for experimental evaluation of ionic liquids (ILs) as entrainers was proposed. For selection of ILs which can be potentially used for the separation of the azeotropic mixture of water and 2-propanol by extractive distillation, vapor–liquid equilibria were measured for ternary systems of water+2-propanol+IL at 100kPa. A previously presented ebulliometer was modified to improve the reliability of measurement of

Lianzhong Zhang; Jianzhi Han; Dongshun Deng; Jianbing Ji

2007-01-01

248

The Structure Of Liquid Water; Novel Insights From Materials Research; Potential Relevance To Homeopathy  

Microsoft Academic Search

This paper provides an interdisciplinary base of information on the structure of liquid water. It begins with a synthesis built on the information base on the structure5 of noncrystalline, inorganic, covalently-bonded condensed liquid phases, such as SiO2, S, Se, P, and H2O, which exists in the materials science literature. The data for water are analyzed through the prism of well-established

Rustum Roy; W. A. Tiller; Iris Bell; M. R. Hoover

2005-01-01

249

The Streaming Potential Coupling Coefficient of Liquid Carbon Dioxide Injected Into Water Saturated Berea Sandstone  

Microsoft Academic Search

The streaming potential coupling coefficient was determined for a liquid carbon dioxide flood of a water-saturated sample of Berea sandstone. The coupling coefficient for the rock\\/water case was determined both before and after each CO2 flood of three samples using a low-pressure static head method. Next, liquid CO2 was allowed to flow through each sample. As the CO2 displaced the

J. R. Moore; S. D. Glaser; H. F. Morrison

2003-01-01

250

A Comparison of Water-Soluble Fertilizer with Liquid Fertilizer for Sport-Fish Pond Fertilization  

Microsoft Academic Search

A finely pulverized, water-soluble fertilizer containing 10% N, 52% P2O5, and 4% K2O was compared with a standard liquid fertilizer (10% N, 34% P2O5, 0% K2O) in ponds containing sunfish Lepomis spp. at the Auburn University Fisheries Research Unit, Auburn, Alabama. Our study suggests that sunfish production with water-soluble fertilizer can equal standard liquid fertilizer results at about 50% of

Yancey G. Rushton; Claude E. Boyd

2000-01-01

251

Calibration of droplet sizing and liquid water content instruments: Survey and analysis  

NASA Astrophysics Data System (ADS)

Results are presented for phase 1 of an effort to establish a unified calibration capability for instruments used for aircraft icing certification and aircraft icing research. Various calibration, data correction, and verification procedures are reviewed and some new techniques are developed for droplet sizing instruments and liquid water content meters. These instruments include a forward scattering spectrometer probe, an optical array probe, and hot-wire type liquid water content meters. Work planned for phase 2 of the effort is described.

Hovenac, E. C.

1986-05-01

252

Retrieval of cloud liquid water using the special sensor microwave imager (SSM\\/I)  

Microsoft Academic Search

The special sensor microwave imager (SSM\\/I) is a microwave radiometer having dual-polarized channels at 19.35, 37, and 85.5 GHz and a vertically polarized channel at 22.235 GHz. The measurements at these frequencies are used to retrieve the liquid water path in precipitating and nonprecipitating clouds over oceans. Three separate algorithms, each accurate for different ranges of liquid water, are combined

Fuzhong Weng; Norman C. Grody

1994-01-01

253

Radio-Frequency-Driven Atmospheric-Pressure Plasmas in Contact with Liquid Water  

Microsoft Academic Search

Atmospheric-pressure plasmas were produced on the surface of liquid water by radio-frequency (RF) power supply. A quartz chamber with an off-center inner electrode was used to generate discharges with a wide range of filling gas pressures. When the chamber was filled with fuel gas and liquid water and a sufficient RF power was supplied to the system, plasmas were observed

Katsuhisa Kitano; Hironori Aoki; Satoshi Hamaguchi

2006-01-01

254

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

255

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

SciTech Connect

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

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

1989-04-01

256

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

257

Liquid water stressed with HV impulses: Effect of polarity on transient pre-breakdown processes  

Microsoft Academic Search

The complexity of the impulse breakdown of liquid water is reflected by the dependency of pre-breakdown processes on the polarity, rise-time and wave-shape of the applied impulses as well as on physical properties, such as electrical conductivity of water itself. Further understanding of the mechanisms of formation and propagation of impulse discharges in water and water solutions is therefore required

M. Hogg; I. V. Timoshkin; M. J. Given; M. P. Wilson; S. J. MacGregor; R. A. Fouracre; J. M. Lehr

2011-01-01

258

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

259

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

260

Three types of liquid water in icy surfaces of celestial bodies  

NASA Astrophysics Data System (ADS)

It is shown that, at temperatures far below the triple point and under appropriate conditions, liquid water can stably or temporarily exist in upper ice-covered surfaces of planetary bodies (like Mars) in three different types:undercooled interfacial water (due to freezing point depression by van der Waals forces and “premelting”),water in brines (due to freezing point depression in solutions), andsub-surface melt water (due to a solid-state greenhouse effect driven heating).The physics behind and the related conditions for these liquid waters to evolve and to exist, and possibly related consequences, are discussed. These calculations are mainly made in view of the possible presence of these sub-surface liquids in the upper surface of the present Mars.

Möhlmann, D.

2011-08-01

261

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

NASA Astrophysics Data System (ADS)

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

Locke, Bruce R.; Shih, Kai-Yuan

2011-06-01

262

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

263

Will Water Mist Extinguish a Liquid Fire Rapidly?  

Microsoft Academic Search

Local professionals are quite worrying about whether a water mist fire suppression system (WMFSS) can extinguish afire rapidly. It was also suggested in the literature that discharging water mist, even under the design operating conditions, might not always control afire rapidly. To explore more on that, a series of experiments on discharging water mist from low\\/moderate-pressure system on gasoline fires

W. K. Chow; Y. Gao; H. Dong; G. Zou; L. Meng

2003-01-01

264

Liquid water: obtaining the right answer for the right reasons  

Microsoft Academic Search

Water is ubiquitous on our planet and plays an essential role in several key chemical and biological processes. Accurate models for water are crucial in understanding, controlling and predicting the physical and chemical properties of complex aqueous systems. Over the last few years we have been developing a molecular-level based approach for a macroscopic model for water that is based

Edoardo Aprà; Alistair P. Rendell; Robert J. Harrison; Vinod Tipparaju; Wibe A. Dejong; Sotiris S. Xantheas

2009-01-01

265

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

PubMed

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

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

2012-07-24

266

Are nanometric films of liquid undercooled interfacial water bio-relevant?  

PubMed

It is known that life processes below the melting point temperature can actively evolve and establish in micrometer-sized (and larger) veins and structures in ice and permafrost soil, filled with unfrozen water. Thermodynamic arguments and experimental results indicate the existence of much smaller nanometer sized thin films of undercooled liquid interfacial (ULI) water on surfaces of micrometer sized and larger mineral particles and microbes in icy environments far below the melting point temperature. This liquid interfacial water can be described in terms of a freezing point depression, which is due to the interfacial pressure of van der Waals forces. The physics behind the possibly also life supporting capability of nanometric films of undercooled liquid interfacial water, which also can "mantle" the surfaces of the much larger and micrometer-sized microbes, is discussed. As described, biological processes do not necessarily have to proceed in the "bulk" of the thin interfacial water, as in "vinical" water and in the micrometer sized veins e.g., but they can be supported or are even made possible already by covering thin mantles of liquid interfacial water. These can provide liquid water for metabolic processes and act as carrier for the necessary transport of nutrients and waste. ULI water supports two different and possibly biologically relevant transport processes: 2D molecular diffusion in the interfacial film, and flow-like due to regelation. ULI-water, which is "lost" by transport into microbes, e.g., will be refilled from the neighbouring ice. In this way, the nanometric liquid environment of microbes in ULI-water is comparable to that of microbes in bulk water. Another probably also biologically relevant property of ULI is, depending on the hydrophobic or hydrophilic character of the surfaces, that it is of lower density (LDL) or higher density (HDL) than bulk water. Furthermore, capillary effects and ions in ULI-water solutions can support, enhance, and stabilize the formation of layers of interfacial water. A more detailed future investigation of the possible support of life processes by nanometric ULI water in ice is a challenge to current cryomicrobiology. Related results of Rivkina et al. [22] indeed indicate that life processes can remain active at water contents corresponding to about or less than two monolayers of ULI water. PMID:19444970

Möhlmann, Diedrich T F

2009-06-01

267

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

268

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

269

Probing intermolecular interactions in water/ionic liquid mixtures by far-infrared spectroscopy.  

PubMed

Far-infrared spectra in the range from 600 to 20 cm-1 of two hydrophilic (1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium tetrafluoroborate) and one hydrophobic (1-butyl-3-methylimidazolium hexafluorophosphate) ionic liquids and their mixtures with water at different concentrations are reported. Shifts of the librational water bands depending on the nature of the anion are found to be related to the strength of the interaction between the water molecules and the anions. For both hydrophilic ionic liquids, the librational band is centered around 460 cm-1, whereas for the hydrophobic ionic liquid, it is shifted to 388 cm-1, indicating less hindered rotation of single water molecules. Multivariate curve resolution, paying special attention to the spectral range from 50 to 350 cm-1, was used to investigate the presence of different species with increasing water concentration. For both hydrophilic ionic liquids, a band located at 153 cm-1 was resolved into two different contributions. A small contribution at 202 cm-1 can be attributed to intermolecular interactions between water molecules forming dimers. The major contribution (centered at 148 cm-1) corresponds to water molecules that do not bond to each other via H-bonding. It is therefore assigned to a hindered translation arising from the stretching of the hydrogen bond between BF4- anions and water molecules. Formation of water dimers in the hydrophobic ionic liquid does not occur. Furthermore, the spectral contribution of the stretching of H-bonds between water molecules and PF6- cannot be unambiguously detected, which indicates an extremely weak interaction between water molecules and this anion. PMID:17408256

Dominguez-Vidal, Ana; Kaun, Nina; Ayora-Cañada, Maria Jose; Lendl, Bernhard

2007-04-05

270

Determination of fentanyl in biological and water samples using single-drop liquid–liquid–liquid microextraction coupled with high-performance liquid chromatography  

Microsoft Academic Search

A single-drop liquid–liquid–liquid microextraction (LLLME) method coupled with high-performance liquid chromatography (HPLC) was developed for the determination of fentanyl in biological (plasma and urine) and wastewater samples. Fentanyl is a potent synthetic narcotic analgesic administered in the form of a transdermal patch for the management of chronic pain. Fentanyl was extracted from 0.01M NaOH solution (donor phase) into a thin

H. Ebrahimzadeh; Y. Yamini; A. Gholizade; A. Sedighi; S. Kasraee

2008-01-01

271

Ultrafast Conversions Between Hydrogen Bonded Structures in Liquid Water Observed by Femtosecond X-Ray Spectroscopy.  

National Technical Information Service (NTIS)

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray ...

A. M. Lindenberg H. Wen N. Huse R. W. Schoenlein

2010-01-01

272

Comparison of Copper Speciation in Estuarine Water Measured Using Analytical Voltammetry and Supported Liquid Membrane Techniques  

Microsoft Academic Search

The supported liquid membrane (SLM) is a promising separation and preconcentration technique that is well- suited for trace metal speciation in natural waters. The technique is based on the selective complexation of metal ions by a hydrophobic ligand (carrier) dissolved in a water- immiscible organic solvent immobilized in a porous, inert membrane. This membrane separates two aqueous solutions: the test

KURIA N DUNGU; MATTHEW P. H URST; KENNETH W. B RULAND

2005-01-01

273

Liquid Water Transport in Gas Diffusion Layer of Polymer Electrolyte Fuel Cells  

Microsoft Academic Search

High-current-density performance of polymer electrolyte fuel cells ~PEFCs! is known to be limited by transport of reactants and products. In addition, at high current densities, excessive amount of water is generated and condenses, filling the pores of electrodes with liquid water, and hence limiting the reactant transport to active catalyst. This phenomenon known as ''flooding'' is an important limiting factor

Ugur Pasaogullari; C. Y. Wang

2004-01-01

274

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

275

The influence of water on the structural and transport properties of model ionic liquids  

Microsoft Academic Search

Molecular dynamics simulations are used to investigate the influence of water on model ionic liquids. Several models, where the ions vary in size, and in the location of the charge with respect to the center of mass, are considered. Particular attention is focused on the variation in transport properties (diffusion coefficients, shear viscosity, and electrical conductivity) with water concentration. An

Heidrun V. Spohr; G. N. Patey

2010-01-01

276

Determination of octanol-water partition coefficients using gradient liquid chromatography  

Microsoft Academic Search

The use of liquid chromatography to estimate octanol-water partition coefficients, log Kow, has been demonstrated. The capacity factor with a mobile phase of 100% water, kw, has been found to be a useful Chromatographic parameter. Values of Kw were derived from a computer software package (Hipac-G), designed for optimization and simulation of gradient LC systems. The chromatographic parameter, Kw, correlates

V. Makovskaya; J. R. Dean; W. R. Tomlinson; S. M. Hitchen; M. Comber

1995-01-01

277

Effect of hydrogen bonds on the thermodynamic behavior of liquid water  

Microsoft Academic Search

We propose an extension of the van der Waals equation which is designed to incorporate, in an approximate fashion, the effects of the network of hydrogen bonds that exists in liquid water. The resulting model qualitatively predicts the unique thermodynamic properties of water, including those of the deeply supercooled states. It also reconciles two proposals for the phase behavior of

Peter H. Poole; Francesco Sciortino; Tor Grande; H. Eugene Stanley; C. Austen Angell

1994-01-01

278

Measurements of Rn222 in water by liquid scintillation counting of polycarbonates  

Microsoft Academic Search

This work presents the results of a preliminary study of a new technique for measurement of 222Rn in water. The technique involves exposure in water of polycarbonates with high absorption ability to radon followed by liquid scintillation counting (LSC) of the polycarbonates. The LSC is used to register the alpha and beta radiation emitted by radon that is absorbed in

I. Dimitrova; K. Mitev; V. Zhivkova; S. Georgiev; G. Gerganov; D. Pressyanov

2011-01-01

279

Radio-Frequency Method for Measuring the Water Content of Liquids  

Microsoft Academic Search

The method for radio-frequency measurements of water content in nonaqueous liquids is improved, and a procedure for measuring the concentration of water emulsified in oils and diesel fuels is described. Correlations between the composition of emulsions studied and the attenuation of the energy of electromagnetic radiation passing through the emulsions are revealed.

V. A. Bannyi; A. V. Makarevich; L. S. Pinchuk; B. G. An

2002-01-01

280

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

281

Clathrate-like Ordering in Liquid Water Induced by Infrared Irradiation  

Microsoft Academic Search

X-ray diffraction experiments revealed that when liquid water is exposed to infrared irradiation a solidlike ordering of water molecules is induced. The ordered structure was found to be either of the clathrate hydrates I and II or their mixture. It takes more than 24 h for the ordered structure to return to the original state, as long as it is

Tetsuro Yokono; Shigezo Shimokawa; Tadahiko Mizuno; Makio Yokono; Toshio Yokokawa

2004-01-01

282

Using Magnetic Induction to Explore Liquid Water in icy Satellites  

Microsoft Academic Search

Magnetic field observations made by Galileo in the vicinity of Europa, Ganymede and Callisto showed that strong magnetic induction fields emanate from these moons in response to the rotating magnetic field of Jupiter. Further analyses have shown that the magnetic induction fields are consistent with the presence of subsurface liquid oceans in these moons. Many independent lines of geological and

K. K. Khurana

2004-01-01

283

Thermodynamics and quantum corrections from molecular dynamics for liquid water  

Microsoft Academic Search

In principle, given the potential energy function, the values of thermodynamic variables can be computed from statistical mechanics for a system of molecules. In practice for the liquid state, however, two barriers must be overcome. This paper treats the first problem, how to quantum correct the classical mechanical thermodynamic values available from molecular dynamics, Monte Carlo, perturbation, or integral methods

Peter H. Berens; Donald H. J. Mackay; Gary M. White; Kent R. Wilson

1983-01-01

284

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

285

Short-range precipitation forecasts using assimilation of simulated satellite water vapor profiles and column cloud liquid water amounts  

SciTech Connect

These observing system simulation experiments investigate the assimilation of satellite-observed water vapor and cloud liquid water data in the initialization of a limited-area primitive equations model with the goal of improving short-range precipitation forecasts. The assimilation procedure presented includes two aspects: specification of an initial cloud liquid water vertical distribution and diabatic initialization. The satellite data is simulated for the next generation of polar-orbiting satellite instruments, the Advanced Microwave Sounding Unit (AMSU) and the High-Resolution Infrared Sounder (HIRS), which are scheduled to be launched on the NOAA-K satellite in the mid-1990s. Based on cloud-top height and total column cloud liquid water amounts simulated for satellite data a diagnostic method is used to specify an initial cloud water vertical distribution and to modify the initial moisture distribution in cloudy areas. Using a diabatic initialization procedure, the associated latent heating profiles are directly assimilated into the numerical model. The initial heating is estimated by time averaging the latent heat release from convective and large-scale condensation during the early forecast stage after insertion of satellite-observed temperature, water vapor, and cloud water formation.

Wu, X.; Diak, G.R.; Hayden, C.M.; Young, J.A. [Univ. of Wisconsin, Madison, WI (United States)

1995-02-01

286

Liquid-liquid immiscibility in single-component network-forming fluids: Model calculations and implications for polyamorphism in water  

Microsoft Academic Search

Analytical calculations and Monte Carlo simulations of a lattice model of a tetravalent network-forming fluid show liquid-liquid immiscibility at low temperatures. Three types of phase behavior are found to occur: vapor-liquid equilibrium, vapor-liquid equilibrium plus liquid-liquid immiscibility with an upper critical temperature, and vapor-liquid equilibrium plus closed-loop liquid-liquid immiscibility. The coexisting liquids differ appreciably in density, structure, and molecular dynamics.

Christopher J. Roberts; George A. Karayiannakis; Pablo G. Debenedetti

1998-01-01

287

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

PubMed

Multiwalled carbon nanotubes (MWNTs) are functionalized covalently with ionic liquid (IL, 3-aminoethyl imidazolium bromide) which helps good dispersion of IL-functionalized MWNTs (MWNT-IL) in the poly(vinylidene fluoride) (PVDF) matrix. Analysis of transmission electron microscopy (TEM) micrographs suggests ?10 nm coating thickness of MWNTs by ILs, and the covalent linkage of ILs with MWNTs is confirmed from FT-IR and Raman spectra. PVDF nanocomposites with full ?-polymorphic (piezoelectric) form are prepared using MWNT-IL by both the solvent cast and melt-blending methods. The FE-SEM and TEM micrographs indicate that IL-bound MWNTs are homogeneously dispersed within the PVDF matrix. Increasing MWNT-IL concentration in the composites results in increased ? polymorph formation with a concomitant decrease of the ? polymorph, and a 100% ? polymorph formation occurs for 1 wt % MWNT-IL in both the fabrication conditions. A differential scanning calorimetry (DSC) study shows that the MWNT-ILs are an efficient nucleating agent for PVDF crystallization preferentially nucleating the ? form due to its dipolar interactions with PVDF. The glass transition temperature (T(g)) gradually increases with an increase in MWNT-IL concentration, and the storage modulus (G') of the composites increases significantly, showing a maximum increase of 101.3% for 0.5 wt % MWNT-IL. The Young's modulus increases with MWNT-IL concentration, and analysis of the data using the Halpin-Tsai equation suggests that at low concentration they adopt an orientation parallel to the film surface; however, at higher MWNT-IL concentration it is randomly oriented. The tensile strength also increases with an increase in MWNT-IL concentration, and both the Young's modulus and the tensile strength of solvent cast films are lower than melt-blended samples. The elongation at break in the solvent cast samples shows a maximum, but in melt-blended samples it decreases continuously with increasing MWNT-IL concentration. The composites exhibit a very low conductivity percolation threshold at 0.05 wt %, and the three-dimensional conducting network is produced. Higher conductivity (?1 S/cm for 1% MWNT-IL) than other MWNT/PVDF composites has been attributed to the anchored ionic liquid. PMID:23281687

Mandal, Amit; Nandi, Arun K

2013-01-15

288

Predicting water's phase diagram and liquid-state anomalies  

Microsoft Academic Search

Water expands upon freezing, has minima in its volume, heat capacity, and isothermal compressibility with temperature, and shows signs of a first-order phase transition when supercooled. We present an analytical molecular theory that can account for these behaviors. It suggests that local network formation and hydrogen-bonding cooperativity between triplets of neighboring molecules are keys to understanding water's thermodynamics.

Thomas M. Truskett; Ken A. Dill

2002-01-01

289

COMMUNICATIONS Predicting water's phase diagram and liquid-state anomalies  

Microsoft Academic Search

Water expands upon freezing, has minima in its volume, heat capacity, and isothermal compressibility with temperature, and shows signs of a first-order phase transition when supercooled. We present an analytical molecular theory that can account for these behaviors. It suggests that local network formation and hydrogen-bonding cooperativity between triplets of neighboring molecules are keys to understanding water's thermodynamics. © 2002

Thomas M. Trusketta; Ken A. Dill

290

Gibbs Ensemble Simulations of Vapor\\/Liquid Equilibrium Using the Flexible RWK2 Water Potential  

Microsoft Academic Search

Gibbs ensemble Monte Carlo simulations of water vapor\\/liquid equilibrium (VLE) using the flexible fixed charge RWK2 water-water potential are reported. The equilibrium densities, saturation pressures, and critical parameters calculated with this potential are in better agreement with experimental data than are values obtained from the SPC, MSPC\\/E, TIP4P, and TIP5P rigid fixed charge potentials as well as from polarizable interactions,

Zhenhao Duan; Nancy MOller; John H. Weare

2004-01-01

291

Salt effect in vapor-liquid equilibria: correlation of alcohol-, water-, salt systems  

Microsoft Academic Search

The isobaric data of Johnson and Furter for the systems methanol-water, ethanol-water, and l-propanol water, each saturated with a variety of common inorganic salts, can be effectively correlated by means of the van Laar, the Wilson or the Renon equations if pseudo-activity coefficients for the volatile components are computed using a modified reference fugacity for the liquid phase. This reference

R. W. Rousseau; D. L. Ashcraft; E. M. Schoenborn

1972-01-01

292

Investigation on isobaric vapor–liquid equilibrium for acetic acid + water + methyl ethyl ketone + isopropyl acetate  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+methyl ethyl ketone (MEK), MEK+isopropyl acetate, acetic acid+MEK+water and acetic acid+MEK+isopropyl acetate+water are measured at 101.33kPa using a modified Rose cell. The nonideal behavior in vapor phase of binary systems measured in this work is analyzed through calculating fugacity coefficients since mixture containing acetic acid deviates from ideal behavior seriously in

Qiang Xie; Hui Wan; MingJuan Han; GuoFeng Guan

2009-01-01

293

Liquid membrane multiple emulsion process of chromium(VI) separation from waste waters  

Microsoft Academic Search

A liquid membrane (multiple emulsion, water-in-oil-in-water (WIII\\/OII\\/WI)) method of separation of chromium(VI) from simulated waste water has been described. The effect of the variation of the oil-membrane constituents and different types of chemical reactions at the II\\/I interface using aqueous solutions of various strippants (internal phase) have been studied for a critical appraisal of the efficiency of the process. Among

A. K. Chakravarti; S. B. Chowdhury; S. Chakrabarty; T Chakrabarty; D. C. Mukherjee

1995-01-01

294

Liquid membrane multiple emulsion process of separation of copper(II) from waste waters  

Microsoft Academic Search

A liquid membrane (multiple emulsion, water-in-oil-in-water, WIII\\/OII\\/WI) method of separation of copper(II) from simulated waste water has been described. The effect of variation of oil membrane constituents in OII, different concentrations of sulphuric acid as strippant in the internal phase WI, pH and the object ion concentration in the raffinate WIII have been studied in detail with an aim to

A. K. Chakravarti; S. B. Chowdhury; D. C. Mukherjee

2000-01-01

295

Environmental Impact of Mine Liquidation on Groundwater and Surface Water  

Microsoft Academic Search

\\u000a The possibility of disposing of selected kinds of industrial waste into abandoned mines, or into the exploited parts of active\\u000a mines, belongs at present to topical problems in the Czech Republic. In the Czech part of the Lower Silesian Basin, the mining\\u000a activities have stopped in 1995 and the mines are now under a process of liquidation. Mine workings in

Nadia Rapantova; A. Grmela

296

Enhancement of atmospheric liquid water estimation using space-borne remote sensing data  

NASA Astrophysics Data System (ADS)

Clouds strongly affect the energy balance and water cycle, two dominant processes in the climate system. Low-level liquid clouds have the most significant influence on cloud radiative forcing due to their areal extent and frequency. Estimation of atmospheric liquid water contained in low-level clouds and the precipitation underneath them is very important in meteorology, hydrology, and climatology. Space-borne remote sensing data are widely used for global estimation of atmospheric liquid water, given that they have a wider spatial coverage than other data sources and are spanning many years. However, previous space-borne remote sensing techniques have some limitations for estimation of atmospheric liquid water in low-level liquid clouds, namely, the vertical variation of droplet effective radius (DER) is neglected in the calculation of cloud liquid water path (LWP) and the rain underneath low-level liquid clouds can be overlooked. Comprising many state-of-art passive and active instruments, the recently launched NASA A-Train series of satellites provides comprehensive simultaneous information about cloud and precipitation processes. Utilizing A-Train satellite data and ship-borne data from the East Pacific Investigation of Climate (EPIC) campaign, in this study investigated is the estimation of liquid water in low-level liquid clouds, and assessed is the potential of cloud microphysical parameters in the estimation of rain from low-level liquid clouds. This study demonstrates that assuming a constant cloud DER can cause biases in the calculation of LWP. It is also shown that accounting for the vertical variation of DER can reduce the mean biases. This study shows that DER generally increases with height in non-drizzling clouds, consistent with aircraft observations. It is found that in drizzling clouds, the vertical gradient of DER is significantly smaller than that in non-drizzling clouds, and it can become negative when the drizzle is heavier than approximately 0.1 mm hr-1. It is shown that the warm rain underneath low-level liquid clouds accounts for 45.0% of occurrences of rain and 27.5% of the rainfall amount over the global ocean areas. Passive microwave techniques underestimate the warm rain over oceans by nearly 48%. Among the cloud microphysical parameters, LWP calculated with DER profile shows the best potential for estimating warm rain, which is neglected by traditional techniques of precipitation estimation.

Chen, Ruiyue

297

Possible physical and thermodynamical evidence for liquid water at the Phoenix landing site  

NASA Astrophysics Data System (ADS)

The objective of the Phoenix mission is to determine if Mars' polar region can support life. Since liquid water is a basic ingredient for life, as we know it, an important goal of the mission is to determine if liquid water exists at the landing site. It is believed that a layer of Martian soil preserves ice by forming a barrier against high temperatures and sublimation, but that exposed ice sublimates without the formation of the liquid phase. Here we show possible independent physical and thermodynamical evidence that besides ice, liquid saline water exists in areas disturbed by the Phoenix Lander. Moreover, we show that the thermodynamics of freeze-thaw cycles can lead to the formation of saline solutions with freezing temperatures lower than current summer ground temperatures on the Phoenix landing site on Mars' Arctic. Thus, we hypothesize that liquid saline water might occur where ground ice exists near the Martian surface. The ideas and results presented in this article provide significant new insights into the behavior of water on Mars.

Rennó, Nilton O.; Bos, Brent J.; Catling, David; Clark, Benton C.; Drube, Line; Fisher, David; Goetz, Walter; Hviid, Stubbe F.; Keller, Horst Uwe; Kok, Jasper F.; Kounaves, Samuel P.; Leer, Kristoffer; Lemmon, Mark; Madsen, Morten Bo; Markiewicz, Wojciech J.; Marshall, John; McKay, Christopher; Mehta, Manish; Smith, Miles; Zorzano, M. P.; Smith, Peter H.; Stoker, Carol; Young, Suzanne M. M.

2009-01-01

298

Possible physical and thermodynamical evidence for liquid water at the Phoenix landing site  

NASA Astrophysics Data System (ADS)

The objective of the Phoenix mission is to determine if Mars' polar region can support life. Since liquid water is a basic ingredient for life, as we know it, an important goal of the mission is to determine if liquid water exists at the landing site. It is believed that a layer of Martian soil preserves ice by forming a barrier against high temperatures and sublimation, but that exposed ice sublimates without the formation of the liquid phase. Here we show possible independent physical and thermodynamical evidence that besides ice, liquid saline water exists in areas disturbed by the Phoenix Lander. Moreover, we show that the thermodynamics of freeze-thaw cycles can lead to the formation of saline solutions with freezing temperatures lower than current summer ground temperatures on the Phoenix landing site on Mars' Arctic. Thus, we hypothesize that liquid saline water might occur where ground ice exists near the Martian surface. The ideas and results presented in this article provide significant new insights into the behavior of water on Mars.

Rennó, Nilton O.; Bos, Brent J.; Catling, David; Clark, Benton C.; Drube, Line; Fisher, David; Goetz, Walter; Hviid, Stubbe F.; Keller, Horst Uwe; Kok, Jasper F.; Kounaves, Samuel P.; Leer, Kristoffer; Lemmon, Mark; Madsen, Morten Bo; Markiewicz, Wojciech J.; Marshall, John; McKay, Christopher; Mehta, Manish; Smith, Miles; Zorzano, M. P.; Smith, Peter H.; Stoker, Carol; Young, Suzanne M. M.

2009-10-01

299

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

NASA Astrophysics Data System (ADS)

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

Pyda, Marek; Nowak-Pyda, Elzbieta

2007-03-01

300

Synergistic effect of dicarbollide anions in liquid-liquid extraction: a molecular dynamics study at the octanol-water interface.  

PubMed

We report a molecular dynamics study of chlorinated cobalt bis(dicarbollide) anions [(B(9)C(2)H(8)Cl(3))(2)Co](-)"CCD(-)" in octanol and at the octanol-water interface, with the main aim to understand why these hydrophobic species act as strong synergists in assisted liquid-liquid cation extraction. Neat octanol is quite heterogeneous and is found to display dual solvation properties, allowing to well solubilize CCD(-), Cs(+) salts in the form of diluted pairs or oligomers, without displaying aggregation. At the aqueous interface, octanol behaves as an amphiphile, forming either monolayers or bilayers, depending on the initial state and confinement conditions. In biphasic octanol-water systems, CCD(-) anions are found to mainly partition to the organic phase, thus attracting Cs(+) or even more hydrophilic counterions like Eu(3+) into that phase. The remaining CCD(-) anions adsorb at the interface, but are less surface active than at the chloroform interface. Finally, we compare the interfacial behavior of the Eu(BTP)(3)(3+) complex in the absence and in the presence of CCD(-) anions and extractant molecules. It is found that when the CCD(-)'s are concentrated enough, the complex is extracted to the octanol phase. Otherwise, it is trapped at the interface, attracted by water. These results are compared to those obtained with chloroform as organic phase and discussed in the context of synergistic effect of CCD(-) in liquid-liquid extraction, pointing to the importance of dual solvation properties of octanol and of the hydrophobic character of CCD(-) for synergistic extraction of cations. PMID:17431527

Chevrot, G; Schurhammer, R; Wipff, G

2007-02-23

301

Quantum dynamical effects in liquid water: A semiclassical study on the diffusion and the infrared absorption spectrum  

Microsoft Academic Search

The important role of liquid water in many areas of science from chemistry, physics, biology, geology to climate research, etc., has motivated numerous theoretical studies of its structure and dynamics. The significance of quantum effects on the properties of water, however, has not yet been fully resolved. In this paper we focus on quantum dynamical effects in liquid water based

Jian Liu; William H. Miller; Francesco Paesani; Wei Zhang; David A. Case

2009-01-01

302

Improved energy efficiency in absorption heat pump through process modification. Part II: Thermodynamic potential of liquid-liquid extraction of ammonia-water mixtures  

Microsoft Academic Search

Extraction-system-attached (ESA) ammonia-water absorption heat pumps were derived from the conventional system as a strategy to improve the energy efficiency of the conventional ammonia-water absorption heat pump. The ESA absorption heat pumps were obtained by attaching a liquid-liquid extraction unit in the conventional system. Theoretical thermodynamic simulation of the ESA and conventional ammonia-water absorption heat pumps showed that a higher

A. S. Olawale; S. S. Adefila

1998-01-01

303

Quaternary liquid–liquid equilibrium: water–phosphoric acid–1-butanol–2-butanone at 25°C  

Microsoft Academic Search

Mutual solubility and tie-line data are presented for the ternary system, water (W)–phosphoric acid (PA)–1-butanol (BuOH) and water–phosphoric acid–2-butanone (methyl ethyl ketone, MEK) at 25°C, as well as for the quaternary system, water–phosphoric acid–1-butanol–2-butanone, at the same conditions. These systems present an unusual behavior since there are no quaternary tie-line planes and the solubility surface presents a shape like a

F Ruiz; M. I Galán; N Boluda

1998-01-01

304

Water-aromatic liquid-liquid-vapour equilibrium calculation using a cubic equation of state  

NASA Astrophysics Data System (ADS)

This paper presents an extension of the procedure developed in the case of water-alkane binaries to mixtures of water and benzene or toluene or xylene or ethylbenzene or diethylbenzene. The method used to calculate the equilibria is based on the Peng-Robinson cubic equation of state modified as regards the coefficient ?( Tr) and on the use of a binary interaction coefficient k iw specific to binaries containing water.

Gao, Guanghua; Daridon, J. L.; Lagourette, B.; Xans, P.

1994-09-01

305

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 5.0ml 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 1min of vortex-assisted extraction was performed. After 5min 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

2013-04-12

306

Vapor–liquid equilibrium in systems (water + organic solvent + salt) at low water concentrations but high ratios of salt to water: experimental results and modeling  

Microsoft Academic Search

Water-free organic solvents are often required in chemical processes. It is common practice to dewater organic solvents by distillation. The operation of such distillation equipment often shows that the design specifications are not met as for example the amount of energy required to remove water to very small concentrations is much higher than expected from reliable data for the vapor–liquid

Günter Uhrig; Xiaoyan Ji; Gerd Maurer

2005-01-01

307

Effect of calcium chloride on the isobaric vapor-liquid equilibrium of 1-propanol + water  

Microsoft Academic Search

The effect of calcium chloride at salt mole fractions from 0.02 to saturation on the vapor-liquid equilibrium (VLE) of 1-propanol + water has been studied at 101.32 kPa using a modified Othmer equilibrium still. The salt exhibited a salting-out effect of the alcohol over the whole range of liquid composition, the azeotrope being eliminated at salt mole fractions greater than

Maria C. Iliuta; Fernand C. Thyrion; Ortansa M. Landauer

1996-01-01

308

Catalysis of deuterium transfer between liquid chloroform and water by anion-exchange resins  

Microsoft Academic Search

Anion-exchange resins in the hydroxide form have been successfully utilized for catalysis of deuterium transfer between water and liquid chloroform under stirred three-phase slurry conditions. In-solution rate constants for CDClâ\\/HâO exchange obtained at 15-35°C with liquid chloroform and 0.10 mol\\/liter NaOH solution under stirred conditions are in good agreement with literature data measured in the absence of bulk chloroform. At

E. A. Symons; J. D. Bonnett

1985-01-01

309

Dialkylimidazolium ionic liquids as electrolytes for hydrogen production from water electrolysis  

Microsoft Academic Search

Imidazolium ionic liquids (ILs) such as BMI·BF4 and BMI·PF6 were studied by cyclic voltammetry (CV). BMI·BF4 was used as an electrolyte for hydrogen production through water electrolysis. The system using this ionic liquid in a conventional electrochemical cell with platinum electrodes at room temperature and atmospheric pressure gives current densities (j) higher than 20mAcm?2 and efficiencies of more than 94.5%.

Roberto F. de Souza; Janine C. Padilha; Reinaldo S. Gonçalves; Joëlle Rault-Berthelot

2006-01-01

310

Adsorption potential of hydrocarbons at the gas-liquid interface of water  

Microsoft Academic Search

In this work, the adsorption potential of 5 hydrocarbons is calculated at the gas-liquid interface of water and compared to the minimum value with the experimental adsorption energy obtained at zero surface coverage by gas chromatography. For 3 of the molecules (n-pentane, n-hexane, and n-heptane), the calculation consisted of dispersion and induction interactions between solute and liquid adsorbent. For 2

Claire Vidal-Madjar; Georges Guiochon; Barry L. Karger

1976-01-01

311

Freely accessible water does not decrease consumption of ethanol liquid diets.  

PubMed

In experimental studies, liquid ethanol diets are usually given as the sole source of nutrition and fluid. Two series of experiments were conducted to examine the effect of freely accessible water on the consumption of ethanol liquid diets in male Long-Evans rats. The consumption of diets and subsequent learning ability of rats were first examined in animals given twice-daily saline injections. One group received diet with no access to water for 12 weeks and was subsequently given free access to water with diets for an additional 12 weeks. A second group was given diet and water ad libitum for 24 weeks. Control animals received an isocaloric sucrose-containing diet (with or without ad libitum access to water). Subsequently, rats were tested for active avoidance learning. In the first 12 weeks, animals with ad libitum access to water drank more diet than did water-restricted animals, and previously water-restricted animals increased their diet consumption when access to water was freely available. All water-restricted animals, in both ethanol- and sucrose-treated groups, showed deficits in active avoidance learning, whereas only ethanol-treated animals in groups with ad libitum access to water showed learning deficits. In the second series of experiments, the effect of saline injections on diet consumption, both in the presence and absence of water, was examined. Although saline injections were associated with decreased diet consumption, there was no effect of free access to water. No differences in blood ethanol concentration were seen among groups. Findings obtained from both series of studies demonstrate that consumption of a Sustacal-based liquid ethanol diet does not decrease if access to water is freely available. PMID:12782247

de Fiebre, NancyEllen C; de Fiebre, Christopher M

2003-02-01

312

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

2011-04-16

313

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

314

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

315

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

PubMed Central

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 (Af) and maximum specific interfacial area (Am) 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.

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

2011-01-01

316

Molecular dynamics simulations of carbon dioxide and water at an ionic liquid interface.  

PubMed

The ionic liquid-carbon dioxide system is of interest because ionic liquids (ILs) have potential to be used for carbon dioxide capture. Because water will be present in a real carbon dioxide capture operation, the interaction between water and the IL is also of interest. Classical molecular dynamics simulations have been used to study the IL 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmim-Tf(2)N) at the interface with vacuum as well as with carbon dioxide, water, or both present in the system. Density and orientational ordering of the ionic liquid molecules at the interface was not significantly altered by the presence of either carbon dioxide or water. The structure of the liquid solutions in the pseudobulk region in the center of the slab was studied using metrics of pairwise association such as radial distribution functions. At the interface, there is an increased density of cation-anion association. When carbon dioxide is present, it forms a dense layer on the surface, and the cation-anion associations at the interface are disrupted, with a corresponding decrease in surface tension. Water slows down the diffusion of the ions as well as carbon dioxide in the bulk. Water has little effect, however, on the interfacial transport dynamics of carbon dioxide. PMID:21800915

Perez-Blanco, Marcos E; Maginn, Edward J

2011-08-15

317

Liquid Water: Obtaining the right answer for the right reasons  

SciTech Connect

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

Apra, Edoardo [ORNL; Harrison, Robert J [ORNL; de Jong, Wibe A [Pacific Northwest National Laboratory (PNNL); Rendell, Alistair P [Australian National University, Canberra, Australia; Tipparaju, Vinod [ORNL; Xantheas, Sotiris [Pacific Northwest National Laboratory (PNNL)

2009-01-01

318

Liquid Water: Obtaining the right answer for the right reasons  

SciTech Connect

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

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

2009-11-14

319

Effect of water uptake on morphology of polymerized ionic liquid block copolymers and random copolymers  

NASA Astrophysics Data System (ADS)

Dynamic studies of polymer morphology probe how the physical properties of polymerized ionic liquids are affected by the environment, such as temperature or moisture. For a series of poly(methyl methacrylate-b-1-[2-(methacryloyloxy)ethyl]-3-Butylimidazolium X^-) block and random copolymers with hydrophilic counterions (X^- = Br^-, HCO3^-, OH^-), the introduction of water vapor to the system can swell the ionic liquid block, causing enlarged hydrophilic domains and swollen channels for ion conduction. This expected expansion of ionic liquid domains in humid environments can be used to intelligently design these copolymers for use in technological applications. The effect of water vapor exposure in these imidazolium-based acrylate polymers is studied by small-angle X-ray scattering. These morphology results will be discussed alongside complementary studies of water uptake and ion conductivity.

Wang, Tsen-Shan; Ye, Yuesheng; Elabd, Yossef; Winey, Karen

2012-02-01

320

Water effect on CO2 absorption for hydroxylammonium based ionic liquids: A molecular dynamics study  

NASA Astrophysics Data System (ADS)

The effect of water content on CO2 absorption in 2-hydroxyethyl-trimethylammonium L-(+)-lactate and tris(2-hydroxyethyl)methylammonium methylsulfate ionic liquids was studied using classical molecular dynamics simulations. The analysis of structural and dynamic properties, together with the energy contributions, showed that molecular-level structuring of CO2-ionic liquids is not affected by the presence of water molecules. Ion-water interactions are developed while maintaining the previous fluids' structuring. The predicted dynamic properties show decreasing molecular mobility, that should lead to increasing viscosity upon water addition for the studied concentration range. Nevertheless, water has a moderate effect on CO2 transport within the studied hydroxylammonium fluids.

Aparicio, Santiago; Atilhan, Mert

2012-05-01

321

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

PubMed

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

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

2012-10-30

322

Experimental study on the interaction of fine water spray with liquid pool fires  

NASA Astrophysics Data System (ADS)

An experimental study of the interaction of a fine water spray with liquid pool fires was performed. Spatially resolved droplet size, velocity distributions, and volume flux of the fine water spray have been obtained in two types of pressure-atomized fine spray, using LDA/APV technology. A method to correct for the presence of droplets is presented and used to determine the heat release rate using a cone calorimeter system, the effects of water spray application on the heat release rate for liquid pool fires were studied. It was found that the volume flux of the water spray is an important factor to determine the liquid pool fire behavior. For the current experimental conditions, the flame was enlarged when lower volume flux of water is used, and suppressed significantly when larger volumes of water are used. Two opposing mechanisms compete when water sprays are applied, which is more complex than the halon agents, such as 1301. The combustion enhancement becomes insignificant when water sprays with the proper characteristics such as adequate volume flux are applied to the diffusion flame in a confined space.

Liao, Guangxuan; Liu, Jianghong; Qin, Jun; Yao, Bin

2001-10-01

323

Molecular dynamics simulation for vapor-liquid coexistence of water in nanocylinder  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulation was conducted in order to investigate the vapor-liquid coexistence of the water molecules in nanopore. In this research, the Lennard-Jones energy parameter between a water molecule and an atom of nanopore was optimized so as to model the contact angle between a water droplet and the carbon material in the fuel cell. The TIP4P/2005 as the model of a water molecule was used; this model produces well the vapor-liquid coexistence line. All of the systems were equilibrated by Nosé-Hoover thermostat. The electrostatic interaction between water molecules was calculated through smooth particle mesh Ewald method. First, we equilibrated a water plug in the single-wall atomistic nanocylinder as a model of nanopore in the fuel cell with radius 1.3nm. Water molecules burst from an interface of the water plug in equilibration. Then, the equilibrium densities both in dense and dilute region ware sampled over 1 ns. The vapor-liquid coexistence line, density profile, free energy profile will be presented in the session.

Mima, Toshiki; Kinefuchi, Ikuya; Yoshimoto, Yuta; Miyoshi, Nobuya; Fukushima, Akinori; Tokumasu, Takashi; Takagi, Shu; Matsumoto, Yoichiro

2013-03-01

324

An experimental study of a water droplet impinging on a liquid surface  

NASA Astrophysics Data System (ADS)

An experimental study is presented for water droplet impingement on a liquid surface. The impaction process was recorded using a high-speed digital camera at 1,000frames/s. The initial droplet diameter was fixed at 3.1mm+/-0.1mm, and all experiments were performed in atmospheric air. The impact velocity was varied from 0.36m/s to 2.2m/s thus varying the impact Weber number from 5.5 to 206. The impacted liquid surface consisted of two fluids, namely water and methoxy-nonafluorobutane, C4F9OCH3 (HFE7100). The depth of the water and HFE7100 pool was varied from 2mm to 25mm. The collision dynamics of water in the HFE7100 pool was observed to be drastically different from that observed for the water droplet impingement on a water pool. The critical impact Weber number for jet breakup was found to be independent of liquid depth. Water-HFE7100 impact resulted in no jet breakup over the range of velocities studied. Therefore, no critical impact Weber number can be defined for water-HFE7100 impact.

Manzello, S. L.; Yang, J. C.

325

The Isochoric Temperature Differential of the Pair Correlation Function of Liquid Water  

NASA Astrophysics Data System (ADS)

Water has been a serious subject of scientific endeavor for over a century, from the time that Roentgen studied its properties prior to his serendipitous discovery of x-rays. The interest in this so-called liquid is, of course, a result of the fact that it is so essential to life. Water's anomalous properties, however, are the main reason it has caught the attention of reaserchers the world over. To a close approximation the structure of liquid water at any instant in time may be considered to be comprised of a weighted fraction of ice I and ice II bonding type structures. The work reported here was carried out to lend validity to this new mixture model concept by attempting to reproduce the experimental pair correlation function of liquid water. Following the ideas of Bosio et al.(Phys. Rev. A; 27,3,1468), subtraction of the two pair correlation functions which share a common isochore helps to elucidate the local structure of the liquid. Rearangement of the first and second neighbor shells occurs with increased temperature differential. This rearangement is interpreted in terms of varying weighted fractions of two bonding types present in the liquid.

Urquidi, Jacob; Singh, Surjit; Wilse Robinson, G.

1997-10-01

326

Gas-liquid-liquid equilibria in mixtures of water, light gases, and hydrocarbons  

SciTech Connect

Phase equilibrium in mixtures of water + light gases and water + heavy hydrocarbons has been investigated with the development of new local composition theory, new equations of state, and new experimental data. The preferential segregation and orientation of molecules due to different energies of molecular interaction has been simulated with square well molecules. Extensive simulation has been made for pure square well fluids and mixtures to find the local composition at wide ranges of states. A theory of local composition has been developed and an equation of state has been obtained for square well fluids. The new local composition theory has been embedded in several equations of state. The pressure of water is decoupled into a polar pressure and non-polar pressure according to the molecular model of water of Jorgensen et al. The polar pressure of water is combined with the BACK equation for the general description of polar fluids and their mixtures. Being derived from the steam table, the Augmented BACK equation is particularly suited for mixtures of water + non-polar substances such as the hydrocarbons. The hydrophobic character of the hydrocarbons had made their mixtures with water a special challenge. A new group contribution equation of state is developed to describe phase equilibrium and volumetric behavior of fluids while requiring only to know the molecular structure of the components. 15 refs., 1 fig.

Chao, K.C.

1990-01-01

327

Generation of liquid water on Mars through the melting of a dusty snowpack  

NASA Astrophysics Data System (ADS)

An optical/thermal model for dusty snowpacks at temperate Martian latitudes is used to investigate the possibility of valley network formation by liquid water that was provided by snowmelts, assuming insolation absorption under clear-sky conditions. The mean-annual surface temperatures for snow and the atmospheric exchange terms of the surface energy balance are constrained by global climate model results. Under favorable conditions, liquid water is generated at atmospheric pressures as low as 30-100 mbar, provided that the substrate is composed of regolith; this condition is in keeping with the cratered terrain expected in an ancient Martian surface.

Clow, G. D.

1987-10-01

328

Models for a liquid-liquid phase transition  

NASA Astrophysics Data System (ADS)

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

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

2002-02-01

329

Vapor-liquid equilibria of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems  

SciTech Connect

Vapor-liquid equilibrium data of the water + 1,3-propanediol and water + 1,3-propanediol + lithium bromide systems were measured at 60, 160, 300, and 760 mmHg at temperatures ranging from 315 to 488 K. The apparatus used in this work is a modified still especially designed for the measurement of low-pressure VLE, in which both liquid and vapor are continuously recirculated. For the analysis of salt-containing solutions, a method incorporating refractometry and gravimetry was used. From the experimental measurements, the effect of lithium bromide on the VLE behavior of water + 1,3-propanediol was investigated. The experimental data of the salt-free system were successfully correlated using the Wilson, NRTL, and UNIQUAC models. In addition, the extended UNIQUAC model of Sander et al. was applied to the VLE calculation of salt-containing mixtures.

Mun, S.Y.; Lee, H.

1999-12-01

330

On the Existence and Stability of Liquid Water on the Surface of Mars Today  

NASA Astrophysics Data System (ADS)

The recent discovery of high concentrations of hydrogen just below the surface of Mars' polar regions by Mars Odyssey has enlivened the debate about past or present life on Mars. The prevailing assumption prior to the discovery was that the liquid water essential for its existence is absent. That assumption was based largely on the calculation of heat and mass transfer coefficients or theoretical climate models. This research uses an experimental approach to determine the feasibility of liquid water under martian conditions, setting the stage for a more empirical approach to the question of life on Mars. Experiments were conducted in three parts: Liquid water's existence was confirmed by droplets observed under martian conditions in part 1; the evolution of frost melting on the surface of various rocks under martian conditions was observed in part 2; and the evaporation rate of water in Petri dishes under Mars-like conditions was determined and compared with the theoretical predictions of various investigators in part 3. The results led to the conclusion that liquid water can be stable for extended periods of time on the martian surface under present-day conditions.

Kuznetz, L. H.; Gan, D. C.

2002-06-01

331

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

NASA Astrophysics Data System (ADS)

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

332

Measurement of Rn-222 in water by absorption in polycarbonates and liquid scintillation counting  

NASA Astrophysics Data System (ADS)

This work presents a new technique for measurement of activity concentrations of Rn-222 in water which is based on liquid scintillation counting (LSC) of polycarbonates exposed in the water. The polycarbonate material has high absorption ability to radon and when exposed in a radon-containing environment (air or water), it absorbs and concentrates radon in its volume. This property of the polycarbonate material is used for sampling 222Rn from the water. The main new element in this work is that it proposes the LSC technique for measurement of the radiation, emitted from the polycarbonate material. This radiation is due to the decay of the absorbed 222Rn and its progeny. Experimental results of LSC of polycarbonate granules and thin foils exposed in water with different activity concentrations of Rn-222 are presented. In all cases a very good linear correlation between the LS counting rate and the activity concentration of the water is found. The LSC of polycarbonates shows similar or even higher sensitivity in comparison to that of LSC of water. The estimated radon-in-water minimal detectable activity concentrations of the proposed method are similar or lower than those of the LSC and lower than those obtained by gamma spectrometry. The proposed method is simple, robust, inexpensive and avoids the need of taking water samples for laboratory analysis. It facilitates studies of the spatial distribution of 222Rn in water basins by exposure of polycarbonate specimens at different spots or depths and subsequent liquid scintillation counting.

Mitev, K.; Dimitrova, I.; Zhivkova, V.; Georgiev, S.; Gerganov, G.; Pressyanov, D.; Boshkova, T.

2012-06-01

333

Extinction of gas and liquid pool fires with water sprays  

Microsoft Academic Search

Extinction in open space of flames from pool fires by downwardly directed water sprays has been investigated on two linear scales, one three times larger than the other. Circular pool fires were employed as fire sources, mostly in the form of gas discharge (methane) from a horizontal sand surface but also, to a limited extent, in the form of heptane

Gunnar Heskestad

2003-01-01

334

[Liquid accumulation medium for isolation of Salmonella from water bodies].  

PubMed

The paper presents the data of experimental and field studies into the efficiency of Salmonella isolation from differently bacterial-contaminated water, by employing 3 storage media. It shows the benefits of using the test medium versus the storage (magnesium and selenite) media commonly applied by practical laboratories. The content of Salmonella in the biotopes of varying biological contamination is shown. PMID:18365464

Golovina, S V; Panasovets, O P; Aleshnia, V V; Zhuravlev, P V; Sibileva, A A; Kovalevskaia, O L

335

Specific heats of saturated water vapor and liquid  

NASA Astrophysics Data System (ADS)

This paper introduces a modification of the expression for the specific heat of saturated vapor attributed to Clausius and widely used in the literature. The proposed formula contains an additional term which avoids the often-criticized negative value of the specific heat of saturated vapor. Results are given for the case of water.

Elsner, Albrecht

1993-09-01

336

Dynamical fluctuating charge force fields: Application to liquid water  

Microsoft Academic Search

A new molecular dynamics model in which the point charges on atomic sites are allowed to fluctuate in response to the environment is developed and applied to water. The idea for treating charges as variables is based on the concept of electronegativity equalization according to which: (a) the electronegativity of an atomic site is dependent on the atom’s type and

Steven W. Rick; Steven J. Stuart; B. J. Berne

1994-01-01

337

Microscopic properties of liquid water from combined ab initio molecular dynamics and energy decomposition studies.  

PubMed

The application of newly developed first-principle modeling techniques to liquid water deepens our understanding of the microscopic origins of its unusual macroscopic properties and behaviour. Here, we review two novel ab initio computational methods: second-generation Car-Parrinello molecular dynamics and decomposition analysis based on absolutely localized molecular orbitals. We show that these two methods in combination not only enable ab initio molecular dynamics simulations on previously inaccessible time and length scales, but also provide unprecedented insights into the nature of hydrogen bonding between water molecules. We discuss recent applications of these methods to water clusters and bulk water. PMID:23928575

Khaliullin, Rustam Z; Kühne, Thomas D

2013-08-09

338

An Integrated Approach toward Retrieving Physically Consistent Profiles of Temperature, Humidity, and Cloud Liquid Water.  

NASA Astrophysics Data System (ADS)

A method is presented for deriving physically consistent profiles of temperature, humidity, and cloud liquid water content. This approach combines a ground-based multichannel microwave radiometer, a cloud radar, a lidar-ceilometer, the nearest operational radiosonde measurement, and ground-level measurements of standard meteorological properties with statistics derived from results of a microphysical cloud model. All measurements are integrated within the framework of optimal estimation to guarantee a retrieved profile with maximum information content. The developed integrated profiling technique (IPT) is applied to synthetic cloud model output as a test of accuracy. It is shown that the liquid water content profiles obtained with the IPT are significantly more accurate than common methods that use the microwave-derived liquid water path to scale the radar reflectivity profile. The IPT is also applied to 2 months of the European Cloud Liquid Water Network (CLIWA-NET) Baltic Sea Experiment (BALTEX) BRIDGE main experiment (BBC) campaign data, considering liquid-phase, nonprecipitating clouds only. Error analysis indicates root-mean-square uncertainties of less than 1 K in temperature and less than 1 g m-3 in humidity, where the relative error in liquid water content ranges from 15% to 25%. A comparison of the vertically integrated humidity profile from the IPT with the nearest operational radiosonde shows an acceptable bias error of 0.13 kg m-2 when the Rosenkranz gas absorption model is used. However, if the Liebe gas absorption model is used, this systematic error increases to -1.24 kg m-2, showing that the IPT humidity retrieval is significantly dependent on the chosen gas absorption model.


Löhnert, Ulrich; Crewell, Susanne; Simmer, Clemens

2004-09-01

339

Crystalline transformation of native cellulose from cellulose I to cellulose ID polymorph by a ball-milling method with a specific amount of water  

Microsoft Academic Search

We have demonstrated for the first time that a mechano-chemical treatment of native cellulose with a specific amount of water (~30 wt%) present ID the cellulose solid state caused the crystalline transformation from cellulose I into cellulose ID polymorph. X-ray diffractometry was used to show that the extent of transformation into cellulose ID increased with milling time. This specific phenomenon

Mariko Ago; Takashi Endo; Takahiro Hirotsu

2004-01-01

340

In-syringe demulsified dispersive liquid-liquid microextraction and high performance liquid chromatography-mass spectrometry for the determination of trace fungicides in environmental water samples.  

PubMed

An in-syringe demulsified dispersive liquid-liquid microextraction (ISD-DLLME) technique was developed using low-density extraction solvents for the highly sensitive determination of the three trace fungicides (azoxystrobin, diethofencarb and pyrimethanil) in water samples by high performance liquid chromatography-mass spectrometry chromatography-diode array detector/electrospray ionisation mass spectrometry. In the proposed technique, a 5-mL syringe was used as an extraction, separation and preconcentration container. The emulsion was obtained after the mixture of toluene (extraction solvent) and methanol (dispersive solvent) was injected into the aqueous bulk of the syringe. The obtained emulsion cleared into two phases without centrifugation, when an aliquot of methanol was introduced as a demulsifier. The separated floating organic extraction solvent was impelled and collected into a pipette tip fitted to the tip of the syringe. Under the optimal conditions, the enrichment factors for azoxystrobin, diethofencarb and pyrimethanil were 239, 200, 195, respectively. The limits of detection, calculated as three times the signal-to-noise ratio (SN(-1)), were 0.026 ?g L(-1) for azoxystrobin, 0.071 ?g L(-1) for diethofencarb and 0.040 ?g L(-1) for pyrimethanil. The repeatability study was carried out by extracting the spiked water samples at concentration levels of 0.02 ?g mL(-1) for all the three fungicides. The relative standard deviations varied between 4.9 and 8.2% (n=5). The recoveries of all the three fungicides from tap, lake and rain water samples at spiking levels of 0.2, 1, 5 ?g L(-1) were in the range of 90.0-105.0%, 86.0-114.0% and 88.6-110.0%, respectively. The proposed ISD-DLLME technique was demonstrated to be simple, practical and efficient for the determination of different kinds of fungicide residues in real water samples. PMID:22483208

Xia, Yating; Cheng, Min; Guo, Feng; Wang, Xiangfang; Cheng, Jing

2012-02-09

341

Salt Effect on the Liquid-Liquid Equilibrium of (Water + Propionic Acid + Cyclohexanol) System at T=(298.2, 303.2, and 308.2) K  

Microsoft Academic Search

Effects of salt and temperature on the liquid phase equilibrium of the (water + propionic acid + cyclohexanol) system were investigated. The liquid-liquid equilibrium data in the presence of KCl for various salt ionic strength of 0.5, 1.0, 1.5, 2.0, and 2.5 mol·dm?3 and in absence of the salt at T=(298.2, 303.2, and 308.2) K were determined. The experimental results

Bahram Ghalami-Choobar; Ali Ghanadzadeh; Shahram Kousarimehr

2011-01-01

342

Drop formation behaviour of a hydrate-forming liquid in a water stream  

NASA Astrophysics Data System (ADS)

Experiments were carried out to investigate the drop formation behaviour of a hydrophobic hydrate-forming liquid, HCFC-141b (CH3CCl2F), at a single nozzle in a water stream under hydrate-formable thermodynamic conditions. Attention was focused on the relation between the clathrate-hydrate formation and the drop formation. It was observed that two discrete hydrate crusts grow along the liquid liquid interface; one forms a frontal cap and the other forms a cylindrical root on each growing drop before its detachment from the nozzle. Most of the latter crust remains at the tip of the nozzle after the detachment of the drop so that it grows into a bell-shaped or nearly cylindrical funnel composed of hydrate deposits in the course of successive growth/detachment of drops. The size of these drops is dependent on the instantaneous diameter of the hydrate-funnel tip rather than the diameter of the nozzle itself. Thus, the size of the drops successively released into the water stream generally varies synchronously with quasi-periodical alternation of growth and breaking of the hydrate funnels. The growth and breaking of the hydrate funnels and the resultant drop-size variation are significantly dependent on the system temperature (or the system subcooling from the liquid/liquid/hydrate equilibrium temperature), the nozzle diameter, and the velocity of the drop-forming liquid through the nozzle.

Kato, Masahiro; Iida, Tomoyuki; Mori, Yasuhiko H.

2000-07-01

343

Fluctuations and relaxation dynamics of liquid water revealed by linear and nonlinear spectroscopy.  

PubMed

Many efforts have been devoted to elucidating the intra- and intermolecular dynamics of liquid water because of their important roles in many fields of science and engineering. Nonlinear spectroscopy is a powerful tool to investigate the dynamics. Because nonlinear response functions are described by more than one time variable, it is possible to analyze static and dynamic mode couplings. Here we review the intra- and intermolecular dynamics of liquid water revealed by recent linear and nonlinear spectroscopic experiments and computer simulations. In particular, we discuss the population relaxation, anisotropy decay, and spectral diffusion of the intra- and intermolecular motions of water and their temperature dependence, which play important roles in ultrafast dynamics and relaxations in water. PMID:23245524

Yagasaki, Takuma; Saito, Shinji

2012-12-05

344

Biphase photoelectrochemistry: A novel cell with a liquid-liquid phase boundary for water photoelectrolysis  

SciTech Connect

A new approach is described that overcomes the problems of photocorrosion and slow heterogeneous electron-transfer kinetics associated with light-assisted water oxidation at semiconductor electrodes. The photoanode, n-MoS{sub 2}, was immersed in an immiscible organic phase, nitromethane, or 1,2-dichloroethane, which insulated it from the aqueous catholyte. Tetrabutylammonium chloride provided ion environment that stabilized n-MoS{sub 2} in the unavoidably water-saturated nitromethane (or dichloroethane) phase. Chemical water oxidation by photoelectrogenerated Cl{sub 2} proceeded through a hypochlorite intermediate that was broken down with the help of RuO{sub 2} colloid catalysts, releasing O{sub 2}, H{sup +}, and Cl{sup {minus}}. Significant reduction of oxygen overvoltage was attained, corresponding to a photoanodic efficiency of 3%. Combined with efficient photocathodes developed in recent years, this could provide prospective foundations for hydrogen fuel generation by photoelectrochemical solar energy conversion.

Cheng, I.F. (Seton Hall Univ., South Orange, NJ (United States)); Jordan, J. (Pennsylvania State Univ., University Park (United States))

1991-05-02

345

On the possibility of liquid water on present-day Mars  

NASA Astrophysics Data System (ADS)

Using a validated general circulation model, we determine where and for how long the surface pressure and surface temperature on Mars meet the minimum requirements for the existence of liquid water in the present climate system: pressures and temperatures above the triple point of water but below the boiling point. We find that for pure liquid water, there are five ``favorable'' regions where these requirements are satisfied: between 0° and 30°N in the plains of Amazonis, Arabia, and Elysium; and in the Southern Hemisphere impact basins of Hellas and Argyre. The combined area of these regions represents 29% of the planet's surface area. In the Amazonis region these requirements are satisfied for a total integrated time of 37 sols each Martian year. In the Hellas basin the number of degree days above zero is 70, which is well above those experienced in the dry valley lake region of Antarctica. These regions are remarkably well correlated with the location of Amazonian paleolakes mapped by Cabrol and Grin [2000] but are poorly correlated with the seepage gullies found by Malin and Edgett [2000]. In both instances, obliquity variations may play a role. For brine solutions the favorable regions expand and could potentially include most of the planet for highly concentrated solutions. 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, even rare events of liquid water formation would be significant since they would dominate the chemistry of the soil and would have biological implications as well. It is therefore worth reassessing the potential for liquid water formation on present day Mars, particularly in light of recent Mars Global Surveyor observations.

Haberle, Robert M.; McKay, Christopher P.; Schaeffer, James; Cabrol, Nathalie A.; Grin, Edmon A.; Zent, Aaron P.; Quinn, Richard

2001-10-01

346

Interactions between drops of a molten aluminum-lithium alloy and liquid water  

Microsoft Academic Search

In certain hypothesized nuclear reactor accident scenarios, 1- to 10-g drops of molten aluminum-lithium alloys might contact liquid water. Because vigorous steam explosions have occurred when large amounts of molten aluminum-lithium alloys were released into water or other coolants, it becomes important to know whether there will be explosions if smaller amounts of these molten alloys similarly come into contact

Lloyd S. Nelson; Patricia M. Duda; David A. Hyndman

1994-01-01

347

The influence of water percolation on flow of light non aqueous phase liquids in soil  

Microsoft Academic Search

Keywords<\\/strong> ,: multi-phase flow, entrapment, numerical modeling, similarity solution, horizontal migration, percolation theory, relative permeability.In this thesis the physical behavior of Light Non-Aqueous Phase Liquids (LNAPL) at the capillary fringe, is studied with multiphase flow models. Phenomena like a fluctuating water table or percolation of (infiltration) water have a large impact on this behavior. Both the geometry and the mobility

A. Marsman

2002-01-01

348

Determination of gross alpha and beta activities in water samples by liquid scintillation counting  

Microsoft Academic Search

Liquid scintillation counting (LSC) has been proposed for the determination of the gross alpha and beta activities of aqueous\\u000a samples because of its simplicity and low associated costs. In this paper, protocols for gross alpha and beta activities determination\\u000a of the samples of waste water from the discharges of radiochemical laboratories and of the water samples from underground\\u000a low-level waste

P. Staffová; M. N?mec; J. John

2006-01-01

349

Adsorption of 1-alkyl-4-methylpyridinium salts at solid-liquid and water-air interfaces  

Microsoft Academic Search

Determinations of the adsorption at both solid-liquid and water-air interfaces of 1-alkyl-4-methylpyridinium salts have been performed.At the water-air interface, measurements of the surface tension as a function of the bulk concentration of 1-dodecyl-4-methylpyridinium chloride were performed. Mathematical treatment of the resulting isotherm allowed the size of the adsorbed molecule and the CMC to be obtained.The solid adsorbent was a titanium

S. Ardizzone; C. L. Bianchi; P. Drago; D. Mozzanica; P. Quagliotto; P. Savarino; G. Viscardi

1996-01-01

350

A computer simulation study of the liquid-vapor coexistence curve of water  

Microsoft Academic Search

The liquid–vapor coexistence curve of a model water (the extended simple point charge model, SPCE) is evaluated by molecular dynamics simulation in the (N,V,E) ensemble. It is shown that the simulated system (N=256 water molecules) is too small to present a spinodal decomposition and, hence, can be described by a classical equation of state whose the critical parameters (Tc=651.7 K,

Yves Guissani; Bertrand Guillot

1993-01-01

351

Vapor-liquid equilibrium in low pressure water+congener mixtures  

Microsoft Academic Search

Vapor-liquid equilibrium in binary water+congeners mixtures found in alcoholic distillation has been analyzed using the Peng-Robinson\\u000a equation of state and one of the most popular modern mixing rules, the Wong-Sandler model. Accurate modeling of the concentration\\u000a of congeners (substances different from ethanol and water) in the vapor phase is of special importance because these substances\\u000a give some special characteristics of

Claudio Alonso Faúndez; Felipe Andrés Urbina; José Omar Valderrama

2009-01-01

352

Molybdenum electrodes for hydrogen production by water electrolysis using ionic liquid electrolytes  

Microsoft Academic Search

The hydrogen production by water electrolysis was tested with different electrocatalysts (molybdenum, nickel, iron alloys containing chromium, manganese and nickel) using aqueous solutions of ionic liquid (IL) like 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4). The hydrogen evolution reaction (HER) was performed at room temperature in a potential of ?1.7V (PtQRE). A Hoffman cell apparatus was used to water electrolysis with current density values,

Roberto F. de Souza; Gabriel Loget; Janine C. Padilha; Emilse M. A. Martini; Michele O. de Souza

2008-01-01

353

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

354

Two-step emulsification process for water-in-oil-in-water multiple emulsions stabilized by lamellar liquid crystals.  

PubMed

Multiple emulsions, also called complex emulsions or multiphase emulsions, include water-in-oil-in-water (W/O/W)-type and oil-in-water-in-oil (O/W/O)-type emulsions. W/O/W-type multiple emulsions, obtained by utilizing lamellar liquid crystal with a layer structure showing optical anisotropy at the periphery of emulsion droplets, are superior in stability to O/W/O-type emulsions. In this study, we investigated a two-step emulsification process for a W/O/W-type multiple emulsion utilizing liquid crystal emulsification. We found that a W/O/W-type multiple emulsion containing lamellar liquid crystal can be prepared by mixing a W/O-type emulsion (prepared by primary emulsification) with a lamellar liquid crystal obtained from poly(oxyethylene) stearyl ether, cetyl alcohol, and water, and by dispersing and emulsifying the mixture in an outer aqueous phase. When poly(oxyethylene) stearyl ether and cetyl alcohol are each used in a given amount and the amount of water added is varied from 0 to 15 g (total amount of emulsion, 100 g), a W/O/W-type multiple emulsion is efficiently prepared. When the W/O/W-type multiple emulsion was held in a thermostatic bath at 25°C, the droplet size distribution showed no change 0, 30, or 60 days after preparation. Moreover, the W/O/W-type multiple emulsion strongly encapsulated Uranine in the inner aqueous phase as compared with emulsions prepared by one-step emulsification. PMID:22864511

Ito, Toshifumi; Tsuji, Yukitaka; Aramaki, Kenji; Tonooka, Noriaki

2012-01-01

355

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

PubMed

Photoreduction of [P(2)W(18)O(62)](6-), [S(2)Mo(18)O(62)](4-), and [S(2)W(18)O(62)](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 = BF(4), PF(6)) 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 [P(2)W(18)O(62)](6-) was photo-reduced at the water-diethylether interface. In all cases, water acted as the electron donor to give the overall process: 4POM + 2H(2)O + h? ? 4POM(-) + 4H(+) + O(2). 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

2012-07-02

356

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

357

SALT EFFECT IN LIQUID-LIQUID EQUILIBRIA OF ACETIC ACID-WATER-BENZENE SYSTEM  

Microsoft Academic Search

The effect of sodium sulphate, potassium-sulphate and potassium chloride on the distribution of acetic acid between benzene and water at 35°C is reported. Distribution data of the three quaternaries have been determined at salt saturation and unsaturation in each case, as well as the basic ternary in the absence of salt at that temperature. The simple method of Setschenov is

A. S. NARAYANA; R. NISCHAL; R. PATEL; K. G. PARIKH; R. K. SINGH

1990-01-01

358

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

359

Vapor–liquid equilibrium of systems containing alcohols, water, carbon dioxide and hydrocarbons using SAFT  

Microsoft Academic Search

The statistical associating fluid theory (SAFT) equation of state is employed for the correlation and prediction of vapor–liquid equilibrium (VLE) of eighteen binary mixtures. These include water with methane, ethane, propane, butane, propylene, carbon dioxide, methanol, ethanol and ethylene glycol (EG), ethanol with ethane, propane, butane and propylene, methanol with methane, ethane and carbon dioxide and finally EG with methane

Xiao-Sen Li; Peter Englezos

2004-01-01

360

Ex situ visualization of liquid water transport in PEM fuel cell gas diffusion layers  

Microsoft Academic Search

A novel fluorescence microscopy technique for visualizing the transport of liquid water in unsaturated hydrophobic fibrous media has been developed and is applied to the gas diffusion layer of a PEM fuel cell. In the experiments, fluorescein dye solution is pumped through the fibrous hydrophobic gas diffusion layer (GDL) and imaged with fluorescence microscopy. Transient image intensity data is correlated

S. Litster; D. Sinton; N. Djilali

2006-01-01

361

Heterogeneous Adsorbed and Salty Liquid Water at the Phoenix Landing Site, Mars  

NASA Astrophysics Data System (ADS)

Laboratory dielectric measurements were used to interpret the TECP data. These data are consistent with a salty (NaClO4 and/or MgCl2) liquid solution with a eutectic temperature near 239 K and the presence of adsorbed water in the regolith.

Stillman, D. E.; Grimm, R. E.

2011-03-01

362

Comparison of gas and liquid chromatography for analysing polar pesticides in water samples  

Microsoft Academic Search

This review describes the applications of gas chromatography (GC) and liquid chromatography (LC) in the analysis of selected groups of pesticides in water. The attention is focussed on the most popular (in terms of amounts produced and applied) pesticide classes, i.e., carbamates, phenylureas, triazines, phenoxy acetic acid derivatives and chlorinated phenols. The use of GC and LC for the analysis

I. Liška; J. Slobodník

1996-01-01

363

Estimating Integrated Cloud Liquid Water from Extended Time Observations of Solar Irradiance.  

National Technical Information Service (NTIS)

An analysis technique used to estimate the integrated liquid water content (LWC) from the measured solar irradiance is described. The cloud transmittance is computed by dividing the irradiance measured at some time by a clear sky value obtained at the sam...

C. W. Fairall R. E. Rabadi J. B. Snider

1990-01-01

364

Laboratory measurements of charge separation in low liquid water content conditions and low impact velocity  

NASA Astrophysics Data System (ADS)

A laboratory investigation of the electric charge separated in collisions between vapor-grown ice crystals and a target growing by riming is presented in this work, with the goal of studying the performance of the noninductive mechanism under microphysical conditions similar to some of those which occur in the stratiform regions of the mesoscale convective systems. A series of experiments were conducted by using a target of 2 mm in diameter, for ambient temperatures between -7°C and -13°C, effective liquid water content between 0.05 and 0.5 g m-3, and air speeds between 1 and 3 m s-1. Charge diagrams of the sign of the electric charge transfer on the rimer as a function of the ambient temperature and the effective liquid water content for each velocity are presented. The results show that the riming target charges positive for temperatures above -10°C. For temperatures below -10°C, the charging is positive for high liquid water content and negative for low liquid water content. The magnitude of the charge transfer per collision under the studied conditions ranges from 0.01 to 0.2 fC. The implications of these results to the electrification processes are discussed.

ÁVila, Eldo E.; Lighezzolo, Rafael A.; Castellano, Nesvit E.; Pereyra, Rodolfo G.; Bürgesser, Rodrigo E.

2013-06-01

365

GENERIC, COMPONENT FAILURE DATA BASE FOR LIGHT WATER AND LIQUID SODIUM REACTOR PRAs  

SciTech Connect

A comprehensive generic component failure data base has been developed for light water and liquid sodium reactor probabilistic risk assessments (PRAs) . The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and the Centralized Reliability Data Organization (CREDO) data bases were used to generate component failure rates . Using this approach, most of the failure rates are based on actual plant data rather than existing estimates .

S. A. Eide; S. V. Chmielewski; T. D. Swantz

1990-02-01

366

Patterns of three-liquid-phase behavior illustated by alcohol-hydrocarbon-water-salt mixtures  

Microsoft Academic Search

Ten salts were each dissolved in water and the solutions mixed with equal volumes of one of six hydrocarbons and one of ten monohydric alcohols. The resulting multiphase mixtures were examined for the number of coexisting liquid phases and, in some cases, for the partitioning of alcohol among them. Several unusual patterns of phase behavior have been observed. For example,

B. M. Knickerbocker; C. V. Pesheck; H. T. Davis; L. E. Scriven

1982-01-01

367

Characterization of cloud liquid water content distributions from CloudSat  

Microsoft Academic Search

The development of realistic cloud parameterizations requires accurate characterizations of subgrid distributions of thermodynamic variables. To this end, cloud liquid water content (CLWC) distributions are characterized with respect to cloud phase, cloud type, precipitation occurrence, and geolocation using CloudSat radar measurements. The probability density function (PDF) of CLWC is estimated using maximum likelihood estimation. The best-estimated PDF of CLWC is

Seungwon Lee; Brian H. Kahn; João Teixeira

2010-01-01

368

On cloud radar and microwave radiometer measurements of stratus cloud liquid water profiles  

Microsoft Academic Search

We show a method for determining stratus cloud liquid water profiles using a microwave radiometer and cloud radar. This method is independent of the radar calibration and the cloud-droplet size distribution provided that the sixth moment of the size distribution can be related to the square of the third moment. We have calculated these moments with a wide variety of

A. S. Frisch; G. Feingold; C. W. Fairall; T. Uttal; J. B. Snider

1998-01-01

369

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

Microsoft Academic Search

Measurements of the total ion yield (TIY) x-ray absorption spectrum (XAS) of liquid water by Wilson et al (2002 J. Phys.: Condens. Matter14 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

Christopher D Cappa; Jared D Smith; Kevin R Wilson; Richard J Saykally

2008-01-01

370

Optimization of pH controlled liquid hot water pretreatment of corn stover  

Microsoft Academic Search

Controlled pH, liquid hot water pretreatment of corn stover has been optimized for enzyme digestibility with respect to processing temperature and time. This processing technology does not require the addition of chemicals such as sulfuric acid, lime, or ammonia that add cost to the process because these chemicals must be neutralized or recovered in addition to the significant expense of

Nathan Mosier; Richard Hendrickson; Nancy Ho; Miroslav Sedlak; Michael R. Ladisch

2005-01-01

371

The Role of Liquid Water in Crystalline Hydrate Dehydration: Copper sulphate pentahydrate  

Microsoft Academic Search

Simultaneous Differential Thermal Analysis\\/Thermogravimetric experiments carried out on one large single crystal, several small single crystals and powdered crystals of pentahydrate copper sulphate have been used to demonstrate the role that retained liquid water plays in maintaining crystal morphology during dehydration. Measured activation energies for stepwise dehydration in the system show the presence of solution-based transformations provide lower energy paths

S. de Castelnuovo; J. B. Harness; I. J. McColm

2001-01-01

372

Washing methanogenic cells with the liquid fraction from a Mars soil simulant and water mixture.  

PubMed

Certain methanogens have been shown to grow on a Mars soil simulant following a washing procedure using a carbonate buffer. In experiments where liquid fractions from the soil simulant and water mixtures were used in place of the buffer, two out of three of the species demonstrated significantly greater methane production compared to the buffer. PMID:16828907

Ormond, David Ryan; Kral, Timothy A

2006-07-10

373

Effect of cationic surfactants on organic liquid-water capillary pressure-saturation relationships  

Microsoft Academic Search

Many solutes, either naturally occurring or introduced, are surface active and sorb preferentially at the interfaces of subsurface systems. In multiphase systems, the sorption of surfactants affects the capillary pressure-saturation relationships, fundamental constitutive relationships in the modeling of multiphase flow. In this study, the impact of surfactant sorption on capillary pressure relationships for organic liquid-waters systems was demonstrated by qualitatively

A. H. Demond; K. F. Hayes; F. N. Desai

1994-01-01

374

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

375

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

376

A complete dielectric response model for liquid water: a solution of the Bethe ridge problem.  

PubMed

We present a complete yet computationally simple model for the dielectric response function of liquid water over the energy-momentum plane, which, in contrast to earlier models, is consistent with the recent inelastic X-ray scattering spectroscopy data at both zero and finite momentum transfer values. The model follows Ritchie's extended-Drude algorithm and is particularly effective at the region of the Bethe ridge, substantially improving previous models. The present development allows for a more accurate simulation of the inelastic scattering and energy deposition process of low-energy electrons in liquid water and other biomaterials. As an example, we calculate the stopping power of liquid water for electrons over the 0.1-10 keV range where direct experimental measurements are still impractical and the Bethe stopping formula is inaccurate. The new stopping power values are up to 30-40% lower than previous calculations. Within the range of validity of the first Born approximation, the new values are accurate to within the experimental uncertainties (a few percent). At the low end, the introduction of Born corrections raises the uncertainty to perhaps approximately 10%. Thus the present model helps extend the ICRU electron stopping power database for liquid water down to about two orders of magnitude with a comparable level of uncertainty. PMID:16038591

Emfietzoglou, Dimitris; Cucinotta, Francis A; Nikjoo, Hooshang

2005-08-01

377

Scale Invariance in Liquid Water Distributions in Marine Stratocumulus. Part II: Multifractal Properties and Intermittency Issues  

Microsoft Academic Search

This is the second of two papers analyzing the internal liquid water content (LWC) structure of marine stratocumulus (Sc) based on observations taken during the First ICCP (International Commission on Cloud Physics) Regional Experiment (FIRE) 1987 and Atlantic Stratocumulus Transition Experiment (ASTEX) 1992 field programs. Part I examined wavenumber spectra and the three-decade scale range (tens of meters to tens

Alexander Marshak; Anthony Davis; Warren Wiscombe; Robert Cahalan

1997-01-01

378

Liquid–Liquid Equilibria of Oxygenate Fuel Additives with Water at 298.15 K: Ternary and Quaternary Aqueous Systems of Diisopropyl Ether and Hydrocarbons with 2Propanol  

Microsoft Academic Search

Experimental tie-line data were determined for one ternary system, water + diisopropyl ether + n-heptane and two quaternary systems, water + diisopropyl ether + 2-propanol + n-heptane or toluene at 298.15 K and ambient pressure. The experimental liquid–liquid equilibrium data were successfully correlated\\u000a using a modified UNIQUAC model with ternary and quaternary mixture parameters, in addition to the binary ones.

Yao Chen; Yanhui Dong

2005-01-01

379

Variation in morphology of gold nanoparticles synthesized by the spontaneous reduction of aqueous chloroaurate ions by alkylated tyrosine at a liquid–liquid and air–water interface  

Microsoft Academic Search

We demonstrate the formation of gold nanocrystals of different morphologies using alkylated tyrosine (AT) as a reducing agent at a liquid-liquid and air-water interface. The reduction of aqueous chloroaurate ions occurs in a single step wherein the AT molecule plays the multifunctional role of a phase transfer, reducing and capping agent. Gold nanoparticles formed at the air-water interface are very

Anita Swami; Ashavani Kumar; Moneesha D'Costa; Renu Pasricha; Murali Sastry

2004-01-01

380

Duration of liquid water habitats on early Mars  

NASA Astrophysics Data System (ADS)

The duration of ice-covered lakes after the initial freezing of the early Mars is presently estimated via a climate model whose critical parameter is the existence of peak seasonal temperatures above freezing, and in which the variability of insolation is included. Under conditions in which meltwater was supplied by an ice source, it is found that water habitats could have been maintained under relatively thin ice sheets for as many as 700 million years after the onset of below-freezing global temperatures. The duration of such habitats on the early Mars therefore exceeds the upper limit of the time envisioned for the emergence of aquatic life on earth.

McKay, C. P.; Davis, W. L.

1991-04-01

381

Evaluation of Solubility and the Gas-Liquid Equilibrium Coefficient of High Concentration Gaseous Ozone to Water  

Microsoft Academic Search

Solubility and the gas-liquid equilibrium coefficient of gaseous ozone to water were examined under higher concentrations of supplied gaseous ozone up to 100 mg\\/L. The experimental and modeling approach was employed to evaluate the gas-liquid equilibrium coefficients and mass transfer of ozone. The gas-liquid equilibrium coefficients were evaluated as 0.35, 0.31 and 0.25 (mg\\/L-liquid)\\/(mg\\/L-gas) at 15, 20 and 30 °C,

Tadao Mizuno; Hiroshi Tsuno

2010-01-01

382

Solubilization of an Ionic Liquid, l-Butyl-3-methylimidazolium Hexafluorophosphate, in a Surfactant-Water System  

Microsoft Academic Search

The amphiphilic association structures were determined in the system; water, Laureth 4 (approximately C12(EO) 4), and the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate ([bmim[PF6]), using visual observation and small angle x-ray diffraction. The system showed a lamellar liquid crystal solubilizing the ionic liquid ([bmim[PF6]) to a maximum of 15%, an isotropic surfactant solution dissolving the ionic liquid to a maximum of 39%,

Stig E. Friberg; Qi Yin; Florentina Pavel; Raymond A. Mackay; John D. Holbrey; Kenneth R. Seddon; Patricia A. Aikens

2000-01-01

383

Liquid water transport in a mixed-wet gas diffusion layer of a polymer electrolyte fuel cell  

Microsoft Academic Search

After PTFE treatment, a gas diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC) features mixed wettability, which substantially impacts liquid water transport and associated mass transport losses. A pore-network model is developed in this work to delineate the effect of GDL wettability distribution on pore-scale liquid water transport in a GDL under fuel cell operating conditions. It is

Puneet K. Sinha; Chao-Yang Wang

2008-01-01

384

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

385

Liquid water simulation: a critical examination of cutoff length.  

PubMed

Cutoff treatment is the simplest approach for evaluating intermolecular interactions in molecular dynamics simulations. It has been believed that increasing cutoff length makes simulation results better. On the contrary, our results of the bulk water simulations studied within the range of cutoff lengths, 9-18 A, showed an opposite tendency: the artifact was enhanced by increasing the cutoff length. Especially, in terms of the distance dependent Kirkwood factor GK(r), it was clearly shown that the orientational behavior of water molecules becomes gradually worse as the cutoff length becomes longer. The artifact enhanced by the increased cutoff length led to a reported spurious artifact, i.e., phase transition [Y. Yonetani, Chem. Phys. Lett. 406, 49 (2005)]. Though the cutoff artifact was largely reduced by adopting a force switching technique, it did not completely remove the anomalous cutoff length dependence of the artifact. These results suggest that increasing the cutoff should not be attempted regardless of whether the switching force is adopted or not. PMID:16774347

Yonetani, Yoshiteru

2006-05-28

386

Liquid water simulation: A critical examination of cutoff length  

NASA Astrophysics Data System (ADS)

Cutoff treatment is the simplest approach for evaluating intermolecular interactions in molecular dynamics simulations. It has been believed that increasing cutoff length makes simulation results better. On the contrary, our results of the bulk water simulations studied within the range of cutoff lengths, 9-18 A?, showed an opposite tendency: the artifact was enhanced by increasing the cutoff length. Especially, in terms of the distance dependent Kirkwood factor GK(r), it was clearly shown that the orientational behavior of water molecules becomes gradually worse as the cutoff length becomes longer. The artifact enhanced by the increased cutoff length led to a reported spurious artifact, i.e., phase transition [Y. Yonetani, Chem. Phys. Lett. 406, 49 (2005)]. Though the cutoff artifact was largely reduced by adopting a force switching technique, it did not completely remove the anomalous cutoff length dependence of the artifact. These results suggest that increasing the cutoff should not be attempted regardless of whether the switching force is adopted or not.

Yonetani, Yoshiteru

2006-05-01

387

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

388

In situ metathesis ionic liquid formation dispersive liquid-liquid microextraction for copper determination in water samples by electrothermal atomic absorption spectrometry.  

PubMed

In situ synthesis of ionic liquid extractant for dispersive liquid-liquid microextraction (in situ IL DLLME) combined with electrothermal atomic absorption spectrometry (ET AAS) for determination of copper in water samples was developed. Analytical signals were obtained without the back-extraction of copper from the IL phase prior to its determination by AAS. Some essential parameters of the microextraction and detection techniques such as the pH of sample solution, volume of components for in situ synthesis, matrix interferences and main parameters of graphite furnace atomizer have been studied. Under optimal conditions, high extraction efficiency for copper was achieved for the extraction of 0.7µgL(-1) in 10.0mL of sample solution employing 8?L of 1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (HmimNTf2) as the extraction solvent. The detection limit was found as 0.004µgL(-1) with an enrichment factor of 200. The relative standard deviation (RSD) for seven replicate measurements of 0.7µgL(-1) in sample solution was 4%. The accuracy of the proposed method was evaluated by analysis of the Certified Reference Materials: NIST SRM 2709 (San Joaquin Soil), NBS SRM 2704 (Buffalo River Sediment), NRCC DOLT-2 (Dogfish Liver) and NIST SRM 1643e (Trace Element in Water). The measured copper contents in the reference materials were in satisfactory agreement with the certified values. The method was successfully applied to analysis of the tap, lake and mineral water samples. PMID:24054576

Stanisz, Ewa; Zgo?a-Grze?kowiak, Agnieszka

2013-05-02

389

Computational Study of ions binding to the liquid interface of water  

SciTech Connect

We have performed extensive classical molecular dynamics simulations to examine the molecular transport mechanisms of the I-, Br-, Cl- and Na+ ions across the liquid/vapor interface of water. The potentials of mean force were calculated using the constrained mean force approach and polarizable potential models were used to describe the interactions among the species. The simulated potentials of mean force were found to be different, depending on the type of anion. The larger I- and Br- anions bind more strongly to the liquid/vapor interface of water than did the smaller Cl-ion. It is important to note here that most of the gas phase and solution phase properties of the Br- anion are quite similar to that of the Cl- ion. At the interface, however, the interactions of the Br- and Cl- anions with the water interface appeared to be significantly different. We found that the anions approach the interface more closely do than cations. We have also studied the transport mechanism of an I- across the water/dichloromethane interface. The computed potential of mean force showed no well-defined minimum as in the liquid/vapor case, but a stabilization free energy of about?1 kcal/mol near the interface with respect to the bulk liquid was observed. The I- anion carried a water molecule with it as it crossed the interface. This result is in agreement with a recent experimental study on a similar system. Our work differs from earlier contributions in that our potential models have taken many-body effects into account, and in some cases, these effects cannot be neglected. To the best of our knowledge, this work significantly advances our understanding of molecular processes at the liquid interfaces.

Dang, Liem X. (BATTELLE (PACIFIC NW LAB))

2002-08-12

390

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

SciTech Connect

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

2010-05-01

391

Vapor-liquid equilibria for nitric acid-water and plutonium nitrate-nitric acid-water solutions  

Microsoft Academic Search

The liquid-vapor equilibrium data for nitric acid and nitric acid-plutnonium nitrate-water solutions were examined to develop correlations covering the range of conditions encountered in nuclear fuel reprocessing. The scanty available data for plutonium nitrate solutions are of poor quality but allow an order of magnitude estimate to be made. A formal thermodynamic analysis was attempted initially but was not successful

Maimoni

1980-01-01

392

PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids  

NASA Astrophysics Data System (ADS)

This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the dynamics of the water molecules in the solution is observed in the single-particle relaxational dynamics in the ?eV (nanosecond) time scale, but not in the collective dynamics on the meV (picosecond) time scale. Mallamace et al discuss the dynamic crossover phenomenon in both bulk water and protein hydration water. They collect previous and new experimental data from different experimental techniques and molecular dynamic simulations, and are able to develop a unified picture for the different dynamical findings. Gallo et al present a MD study of confined water in MCM-41S-15 in order to test the applicability of Mode Coupling Theory (MCT) to the dynamics of the hydration water confined in the cylindrical pores of nominal diameter 15 Å. They find that the self dynamics of the hydration water is well described by MCT down to the crossover temperature TC. However, below TC the predictions of idealized MCT no longer apply, since hopping processes intervene and water turns into a strong liquid. Soper raises some questions as to the validity of the analysis method employed to determine the density of water confined in porous silica material MCM-41-S15 from recent neutron scattering experiments. Professors Stanley, Franzese and his collaborators describe an efficient Monte Carlo simulation of a coarse-grained model of water to study the phase diagram of a water monolayer confined in a fixed disordered matrix of hydrophobic nanoparticles between two hydrophobic plates. They find a drastic change of phase behavior of the confined water, such as shortening of the liquid-liquid phase transition line, upon increasing the concentration of the hydrophobic nano-particles. Sciortino and collaborators compute the equilibrium phase diagram of two simple models for patchy particles with three and five patches in a very broad range of pressure and temperature. The three-patch model produces a stable gas-liquid critical point. Yun Liu et al investigate, via small angle neutron scattering and neutron spin echo measurements, the effect of temperature on dynamic cluster formation of co

Chen, Sow-Hsin; Baglioni, Piero

2012-02-01

393

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

394

Determination of cloud liquid water path and precipitable water from microwave attenuation along the satelite-ground path  

NASA Astrophysics Data System (ADS)

To measure cloud liquid water path (LWP) and precipitable water (PW), various techniques have already been developed. However, because of the observation difficulties related to extremely high variability of clouds in time and space, all current measurement techniques, even combined, can't provide global datasets of LWP and PW to meet the needs in numerical weather prediction, precipitation enhancement, atmospheric sciences, and climate change study. This paper presents a concept to determine simultaneously LWP and PW from microwave attenuation by cloud liquid water and water vapor along the satellite-ground path. An investigation has been conducted on the optimal choice of channels and mode of observations. Analysis of errors relevant to the method has also been done. The results show that (1) in principle, the method proposed permits to accurately measure LWP and PW simultaneously; (2) the method with dual- or triple-channel combination can also derive ice water path(IWP) or vertically integrated precipitation (VIP); and (3) from the technical angle, application of this method requires quasi-isotropic or very wide beam transmission and high stability of transmitter and receiver; (4) LWP and PW measurements with this method can be used to calibrate or validate same products provided by other satellite-borne instruments, such as AMSR on the ADEOS-II and CPR on the CloudSat.

Chen, H. B.

395

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

396

Non-porous membrane-assisted liquid-liquid extraction of UV filter compounds from water samples.  

PubMed

A method for the determination of nine UV filter compounds [benzophenone-3 (BP-3), isoamyl methoxycinnamate, 4-methylbenzylidene camphor, octocrylene (OC), butyl methoxydibenzoylmethane, ethylhexyl dimethyl p-aminobenzoate (OD-PABA), ethylhexyl methoxycinnamate (EHMC), ethylhexyl salicylate and homosalate] in water samples was developed and evaluated. The procedure includes non-porous membrane-assisted liquid-liquid extraction (MALLE) and LC-atmospheric pressure photoionization (APPI)-MS/MS. Membrane bags made of different polymeric materials were examined to enable a fast and simple extraction of the target analytes. Among the polymeric materials tested, low- and high-density polyethylene membranes proved to be well suited to adsorb the analytes from water samples. Finally, 2 cm length tailor-made membrane bags were prepared from low-density polyethylene in order to accommodate 100 microL of propanol. The fully optimised protocol provides recoveries from 76% to 101% and limits of detection (LOD) between 0.4 ng L(-1) (OD-PABA) and 16 ng L(-1) (EHMC). The interday repeatability of the whole protocol was below 18%. The effective separation of matrix molecules was proved by only marginal matrix influence during the APPI-MS analysis since no ion suppression effects were observed. During the extraction step, the influence of the matrix was only significant when non-treated wastewater was analysed. The analysis of lake water indicated the presence of seven UV filter compounds included in this study at concentrations between 40 ng L(-1) (BP-3) and 4381 ng L(-1) (OC). In non-treated wastewater several UV filters were also detected at concentration levels as high as 5322 ng L(-1) (OC). PMID:19419722

Rodil, Rosario; Schrader, Steffi; Moeder, Monika

2009-04-18

397

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.

2012-01-01

398

Thermal desorption and IR spectrometric investigation of polyamorphic and polymorphic transformations in cryovacuum condensates of water  

Microsoft Academic Search

Simultaneous thermal desorption and IR spectrometric studies of thermally stimulated transformations in thin films of cryovacuum condensates of water are carried out. It is shown that the temperature interval 12-36 K is the existence region of a high-density form of amorphous solid water. The transition of amorphous high-density ice to a low-density amorphous state starts at T~39 K and is

A. Drobyshev; A. Aldiyarov; D. Zhumagaliuly; V. Kurnosov; N. Tokmoldin

2007-01-01

399

Determination of ultraviolet filters in environmental water samples by temperature-controlled ionic liquid dispersive liquid-phase microextraction.  

PubMed

In the present study, a rapid, highly efficient and environmentally friendly sample preparation method named temperature-controlled ionic liquid dispersive liquid-phase microextraction (TC-IL-DLPME), followed by high performance liquid chromatography (HPLC) was developed for the extraction, preconcentration and determination of four benzophenone-type ultraviolet (UV) filters (viz. benzophenone (BP), 2-hydroxy-4-methoxybenzophenone (BP-3), ethylhexyl salicylate (EHS) and homosalate (HMS)) from water samples. An ultra-hydrophobic ionic liquid (IL) 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ([HMIM][FAP]), was used as the extraction solvent in TC-IL-DLPME. Temperature served two functions here, the promotion of the dispersal of the IL to the aqueous sample solution to form infinitesimal IL drops and increase the interface between them and the target analytes (at high temperature), and the facilitation of mass transfer between the phases, and achievement of phase separation (at low temperature). Due to the ultra-hydrophobic feature and high density of the extraction solvent, complete phase separation could be effected by centrifugation. Moreover, no disperser solvent was required. Another prominent feature of the procedure was the combination of extraction and centrifugation in a single step, which not only greatly reduced the total analysis time for TC-IL-DLPME but also simplified the sample preparation procedure. Various parameters that affected the extraction efficiency (such as type and volume of extraction solvent, temperature, salt addition, extraction time and pH) were evaluated. Under optimal conditions, the proposed method provided good enrichment factors in the range of 240-350, and relative standard deviations (n=5) below 6.3%. The limits of detection were in the range of 0.2-5.0 ng/mL, depending on the analytes. The linearities were between 1 and 500 ng/mL for BP, 5 and 1000 ng/mL for BP-3, 10 and 1000 ng/mL for HMS and 5 and 1000 ng/mL for EHS. Finally, the proposed method was successfully applied to the determination of UV filters in swimming pool and tap water samples and acceptable relative recoveries over the range of 88.0-116.0% were obtained. PMID:23237715

Zhang, Yufeng; Lee, Hian Kee

2012-11-27

400

An Environmental Chamber to Investigate Liquid Saline Water in the Martian Polar Region  

NASA Astrophysics Data System (ADS)

We present the design of an environmental chamber to simulate the diurnal and seasonal cycles of the Martian polar region. This chamber is being built to aid in the investigation of liquid saline water in Mars' Richardson Crater (72° S, 179° E) and the Mars Phoenix Lander site (68° N, 126° W). Our objective is to: (i) determine the environmental conditions at with brines, formed from perchlorate salts found by the Mars Phoenix Lander, are stable on the surface of Mars and (ii) determine the optical properties of liquid saline water flows hypothesized to exist in Mars' Richardson Crater. The environmental chamber system consists of a vacuum chamber with six internal thermal plates. The plates are arranged to form a cubic thermal cavity that can be cryogenically cooled by liquid nitrogen. Additional thermal control is attained through the use of resistive patch heaters, which are fixed on the thermal plates. The vacuum chamber inlet is connected to a carbon dioxide dry gas stream, which can be throttled to control the chamber's humidity. The vacuum chamber outlet passes through a chilled mirror hygrometer to measure the chamber humidity before the air exits the vacuum pump. Acknowledgements: This research is supported by a grant from the NASA Astrobiology Program: Exobiology and Evolutionary Biology. Award #09-EXOB09-0050. Keywords: Liquid Saline Water, Cryobrines, Richardson Crater, Mars Phoenix Lander

Elliott, H. M.; Martinez, G. M.; Halleaux, D. G.; Braswell, S. F.; Renno, N. O.

2012-04-01

401

Spontaneous phase transfer of thermosensitive hairy particles between water and an ionic liquid.  

PubMed

This article describes the temperature-induced phase transfer behavior of a series of thermosensitive polymer brush-grafted particles between water and a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TFSI]). Six samples were made by surface-initiated atom transfer radical polymerization: silica particles grafted with poly(methoxypoly(ethylene glycol) methacrylate) (PPEGMMA) with two different molecular weights, poly(methoxytri(ethylene glycol) methacrylate) (PTEGMMA), poly(methoxydi(ethylene glycol) methacrylate) (PDEGMMA), and two copolymers of PEGMMA and TEGMMA with different compositions (P(PEGMMA-co-TEGMMA)-82 and P(PEGMMA-co-TEGMMA)-74). The cloud points of free PPEGMMA with M(n,SEC) of 23 and 40 kDa, P(PEGMMA-co-TEGMMA)-82, P(PEGMMA-co-TEGMMA)-74, and PTEGMMA in [EMIM][TFSI]-saturated water were 95, 94, 80, 72, and 43 °C, respectively. PDEGMMA was not soluble in the ionic liquid-saturated water. PPEGMMA brush-grafted particles moved spontaneously and completely from water to the [EMIM][TFSI] phase upon heating at 80 °C. When cooled to 22 °C, all particles returned to the water layer. From UV-vis absorbance measurements, the transfer temperature (T(tr)) of PPEGMMA-grafted particles from water to the ionic liquid was 42 °C. Thermodynamic analysis showed that the particle transfer was an entropically driven process. P(PEGMMA-co-TEGMMA)-82, P(PEGMMA-co-TEGMMA)-74, and PTEGMMA brush-grafted particles also underwent reversible and quantitative transfer between the two phases upon heating at 70 °C and cooling at 0 °C; their transfer temperatures from water to [EMIM][TFSI] were 36, 30, and 16 °C, respectively. T(tr) was a linear function of the cloud point of the corresponding free polymer in ionic liquid-saturated water. In contrast, PDEGMMA-grafted particles moved spontaneously to the ionic liquid layer upon heating but did not return to water even after prolonged stirring at 0 °C. PMID:21189037

Horton, Jonathan M; Bai, Zhifeng; Jiang, Xiaoming; Li, Dejin; Lodge, Timothy P; Zhao, Bin

2010-12-28

402

The role of liquid water in maintaining plate tectonics and the regulation of surface temperature  

NASA Astrophysics Data System (ADS)

Water plays an important role in mantle convection. In the ductile creep regime, the viscosity of wet rocks is weaker than the viscosity of dry rocks by several orders of magnitude. In the brittle regime, the most substantial effect is probably serpentinization which can reduce the friction coefficient by a factor of 2 or more. The difference between the strength of a wet lithosphere and that of a dry lithosphere seems to be big enough to control the very existence of plate tectonics. Because of dehydration due to partial melting the oceanic lithosphere is expected to be essentially dry above some critical depth, around 60-80 km. This would make the lithosphere strong enough to prevent plate motion. Percolation of water from the surface can be the main mechanism supplying water to the upper parts of the lithosphere. This implies that liquid water can be crucial for maintaining plate tectonics. On the other hand, the surface temperature is above the freezing point because of the greenhouse gases such as carbon dioxide. A simple model shows that if the blackbody temperature of the Earth is slightly below the freezing point of water, the feedback between plate tectonics, volcanism, and water and carbon cycles can result in an equilibrium state in which the surface temperature is established within the stability field of liquid water.

Solomatov, V. S.

2001-12-01

403

The dynamic behavior of a liquid ethanol-water mixture: a perspective from quantum chemical topology.  

PubMed

Quantum Chemical Topology (QCT) is used to reveal the dynamics of atom-atom interactions in a liquid. A molecular dynamics simulation was carried out on an ethanol-water liquid mixture at its azeotropic concentration (X(ethanol)=0.899), using high-rank multipolar electrostatics. A thousand (ethanol)(9)-water heterodecamers, respecting the water-ethanol ratio of the azeotropic mixture, were extracted from the simulation. Ab initio electron densities were computed at the B3LYP/6-31+G(d) level for these molecular clusters. A video shows the dynamical behavior of a pattern of bond critical points and atomic interaction lines, fluctuating over 1 ns. A bond critical point distribution revealed the fluctuating behavior of water and ethanol molecules in terms of O-H···O, C-H···O and H···H interactions. Interestingly, the water molecule formed one to six C-H···O and one to four O-H···O interactions as a proton acceptor. We found that the more localized a dynamical bond critical point distribution, the higher the average electron density at its bond critical points. The formation of multiple C-H···O interactions affected the shape of the oxygen basin of the water molecule, which is shown in three dimensions. The hydrogen atoms of water strongly preferred to form H···H interactions with ethanol's alkyl hydrogen atoms over its hydroxyl hydrogen. PMID:21437345

Mejía, Sol M; Mills, Matthew J L; Shaik, Majeed S; Mondragon, Fanor; Popelier, Paul L A

2011-03-25

404

Determination of bromate in drinking water by ultraperformance liquid chromatography-tandem mass spectrometry.  

PubMed

Bromate is a byproduct formed as a result of disinfection of bromide-containing source water with ozone or hypochlorite. The International Agency for Research on Cancer has recognized bromate as a possible human carcinogen, thus it is essential to determine in drinking water. Present work highlights a development of sensitive and fast analytical method for bromate determination in drinking water by using ultraperformance liquid chromatography-tandem mass spectrometry. The quality parameters of the developed method were established, obtaining very low limit of detection (0.01 ng/mL), repeatability and reproducibility have been found to be less than 3% in terms of relative standard deviation when analyzing a bromate standard at 0.05 ?g/mL with 0.4 min analysis time. Developed method was applied for the analysis of metropolitan and bottled water from Saudi Arabia; 22 samples have been analyzed. Bromate was detected in the metropolitan water samples (from desalinization source) at concentrations ranging between 3.43 and 75.04 ng/mL and in the bottled water samples at concentrations ranging between 2.07 and 21.90 ng/mL. Moreover, in comparison to established analytical methods such as liquid chromatography-tandem mass spectrometry, the proposed method was found to be very sensitive, selective and rapid for the routine analysis of bromate at low level in drinking water. PMID:22815069

Alsohaimi, Ibrahim Hotan; Alothman, Zeid Abdullah; Khan, Mohammad Rizwan; Abdalla, Mohammad Abulhassan; Busquets, Rosa; Alomary, Ahmad Khodran

2012-07-20

405

Ultrafast soft X-ray photoelectron spectroscopy at liquid water microjets.  

PubMed

Since the pioneering work of Kai Siegbahn, electron spectroscopy for chemical analysis (ESCA) has been developed into an indispensable analytical technique for surface science. The value of this powerful method of photoelectron spectroscopy (PES, also termed photoemission spectroscopy) and Siegbahn's contributions were recognized in the 1981 Nobel Prize in Physics. The need for high vacuum, however, originally prohibited PES of volatile liquids, and only allowed for investigation of low-vapor-pressure molecules attached to a surface (or close to a surface) or liquid films of low volatility. Only with the invention of liquid beams of volatile liquids compatible with high-vacuum conditions was PES from liquid surfaces under vacuum made feasible. Because of the ubiquity of water interfaces in nature, the liquid water-vacuum interface became a most attractive research topic, particularly over the past 10 years. PES studies of these important aqueous interfaces remained significantly challenging because of the need to develop high-pressure PES methods. For decades, ESCA or PES (termed XPS, for X-ray photoelectron spectroscopy, in the case of soft X-ray photons) was restricted to conventional laboratory X-ray sources or beamlines in synchrotron facilities. This approach enabled frequency domain measurements, but with poor time resolution. Indirect access to time-resolved processes in the condensed phase was only achieved if line-widths could be analyzed or if processes could be related to a fast clock, that is, reference processes that are fast enough and are also well understood in the condensed phase. Just recently, the emergence of high harmonic light sources, providing short-wavelength radiation in ultrashort light pulses, added the dimension of time to the classical ESCA or XPS technique and opened the door to (soft) X-ray photoelectron spectroscopy with ultrahigh time resolution. The combination of high harmonic light sources (providing radiation with laserlike beam qualities) and liquid microjet technology recently enabled the first liquid interface PES experiments in the IR/UV-pump and extreme ultraviolet-probe (EUV-probe) configuration. In this Account, we highlight features of the technology and a number of recent applications, including extreme states of matter and the discovery and detection of short-lived transients of the solvated electron in water. Properties of the EUV radiation, such as its controllable polarization and features of the liquid microjet, will enable unique experiments in the near future. PES measures electron binding energies and angular distributions of photoelectrons, which comprise unique information about electron orbitals and their involvement in chemical bonding. One of the future goals is to use this information to trace molecular orbitals, over time, in chemical reactions or biological transformations. PMID:22075058

Faubel, M; Siefermann, K R; Liu, Y; Abel, B

2011-11-10

406

Determination of radium in water by liquid scintillation counting after preconcentration with ion-exchange resin  

SciTech Connect

A method for the determination of radium in environmental water by means of a liquid scintillation counting technique has been developed. The radium was collected on cation exchange resin with 100% recovery by the batch method. The other radionuclides except uncomplexed elements such as cesium can be removed by washing the resin with 0.01 M EDTA solution at pH 8. The counting sample was prepared by immersing the resin into emulsion liquid scintillator in a Teflon vial. The chemical procedure took about 2 h and the detection limit was 0.03 pCl of /sup 226/Ra/L.

Higuchi, H.; Uesugi, M.; Satoh, K.; Ohashi, N.; Noguchi, M.

1984-04-01

407

Communication: The effect of dispersion corrections on the melting temperature of liquid water  

NASA Astrophysics Data System (ADS)

The melting temperature (Tm) of liquid water with the Becke-Lee-Yang-Parr (BLYP) density functional including dispersion corrections (BLYP-D) and the Thole-type, version 3 (TTM3-F) ab-initio based flexible, polarizable classical potential is reported via constant pressure and constant enthalpy (NPH) molecular dynamics simulations of an ice Ih-liquid coexisting system. Dispersion corrections to BLYP lower Tm to about 360 K, a large improvement over the value of Tm > 400 K previously obtained with the original BLYP functional under the same simulation conditions. For TTM3-F, Tm = 248 K from classical molecular dynamics simulations.

Yoo, Soohaeng; Xantheas, Sotiris S.

2011-03-01

408

Site-site direct correlation functions for three popular molecular models of liquid water  

NASA Astrophysics Data System (ADS)

Direct correlation functions (DCFs) play a pivotal role in the applications of classical density functional theory (DFT) to addressing the thermodynamic properties of inhomogeneous systems beyond the local-density or mean-field approximations. Whereas numerous studies have been dedicated to the radial distribution functions of liquid water - the most important solvent on earth, relatively little attention has been given to the site-site DCFs. The water DCFs are long-ranged and difficult to calculate directly by simulation, and the predictions from conventional liquid-state theories have been rarely calibrated. Here we report a computational procedure for accurate evaluation of the site-site DCFs of liquid water based on three popular molecular models (viz., SPC, SPC/E, and TIP3P). The numerical results provide a benchmark for calibration of conventional liquid-state theories and fresh insights into development of new DFT methods. We show that: (1) the long-range behavior of the site-site DCFs depends on both the molecular model and the thermodynamic condition; (2) the asymptotic limit of DCFs at large distance does not follow the mean-spherical approximation (MSA); (3) individual site-site DCFs are long ranged (~40 nm) but a summation of all DCF pairs exhibits only short-range behavior (~1 nm or a few water diameters); (4) the site-site bridge correlation functions behave as the DCFs, i.e., they are also long-ranged while the summation of all bridge correlation functions is short ranged. Our analytical and numerical analyses of the DCFs provide some simple strategies for possible improvement of the numerical performance of conventional liquid-state theories.

Zhao, Shuangliang; Liu, Yu; Liu, Honglai; Wu, Jianzhong

2013-08-01

409

Site-site direct correlation functions for three popular molecular models of liquid water.  

PubMed

Direct correlation functions (DCFs) play a pivotal role in the applications of classical density functional theory (DFT) to addressing the thermodynamic properties of inhomogeneous systems beyond the local-density or mean-field approximations. Whereas numerous studies have been dedicated to the radial distribution functions of liquid water--the most important solvent on earth, relatively little attention has been given to the site-site DCFs. The water DCFs are long-ranged and difficult to calculate directly by simulation, and the predictions from conventional liquid-state theories have been rarely calibrated. Here we report a computational procedure for accurate evaluation of the site-site DCFs of liquid water based on three popular molecular models (viz., SPC, SPC?E, and TIP3P). The numerical results provide a benchmark for calibration of conventional liquid-state theories and fresh insights into development of new DFT methods. We show that: (1) the long-range behavior of the site-site DCFs depends on both the molecular model and the thermodynamic condition; (2) the asymptotic limit of DCFs at large distance does not follow the mean-spherical approximation (MSA); (3) individual site-site DCFs are long ranged (~40 nm) but a summation of all DCF pairs exhibits only short-range behavior (~1 nm or a few water diameters); (4) the site-site bridge correlation functions behave as the DCFs, i.e., they are also long-ranged while the summation of all bridge correlation functions is short ranged. Our analytical and numerical analyses of the DCFs provide some simple strategies for possible improvement of the numerical performance of conventional liquid-state theories. PMID:23947873

Zhao, Shuangliang; Liu, Yu; Liu, Honglai; Wu, Jianzhong

2013-08-14

410

Molecular Mechanisms of Conduction and Polarization in Water Vapor, Liquid Water, and Ice.  

National Technical Information Service (NTIS)

After a short review of the pertinent prehistory, the investigation starts with water vapor. Thermal ionization requires formation of special association complexes and their dissociation by infrared vibrations. The corresponding process occurs in water an...

A. R. von Hippel

1973-01-01

411

Impact-Induced Liquid-Water Environments on Mars  

NASA Astrophysics Data System (ADS)

The origin and evolution of life on Earth were likely associated with hydrothermal systems (e.g., Corliss et al. 1980, Baross and Hoffman 1985, Holm and Andersson 1995, Shock 1996). Although research has been concentrated on volcanic hydrothermal systems on Earth (e.g., Norton 1984, Farmer 2000) and on Mars (e.g., Allen et al. 1982, Gulick and Baker 1989, Farmer 1996), we suggest that large impacts can, and did, drive similar systems. Impacts are a significant source of thermal energy: melt rock produced in impacts, and hot rock uplifted from depth both provide sources of heat to drive hydrothermal systems. On Mars, these heat sources could provide enough energy to melt an underlying layer of permafrost and perhaps even initiate long-lived crater lakes (Newsom et al. 1996, Cabrol et al. 1999). In terms of the production of heat and the habitable volume incorporated in hydrothermal systems, impacts might have been at least as important as volcanic systems early in planetary development. The oldest (Noachian) surfaces on Mars support this hypothesis: they show very little evidence of volcanism (Carr 1996) and are instead dominated by impact cratering processes. Kring and Cohen (2001, submitted) estimate that more than 6400 craters with diameters greater than 20 km were produced on Mars 3.9 Ga. We present estimates of the lifetimes of hydrothermal systems in Martian craters with sizes ranging from 20 km to 200 km in diameter. Lifetimes calculated assuming convective cooling are 105 years for 100-km craters and several 106 years for 180-km craters (Daubar and Kring 2001, cf. Thorsos et al. 2001). These results may be influenced by an insulating breccia layer, shock heating, and convection of water; these factors are currently being evaluated.

Daubar, I. J.; Kring, D. A.

2001-11-01

412

Estimation of Interfacial Tension between Organic Liquid Mixtures and Water  

SciTech Connect

Knowledge of IFT values for chemical mixtures helps guide the design and analysis of various processes, including NAPL remediation with surfactants or alcohol flushing, enhanced oil recovery, and chemical separation technologies, yet available literature values are sparse. A comprehensive comparison of thermodynamic and empirical models for estimating interfacial tension (IFT) of organic chemical mixtures with water is conducted, mainly focusing on chlorinated organic compounds for 14 ternary, three quaternary, and one quinary systems. Emphasis is placed on novel results for systems with three and four organic chemical compounds, and for systems with composite organic compounds like lard oil and mineral oil. Seven models are evaluated: the ideal and nonideal monolayer models (MLID and MLNID), the ideal and nonideal mutual solubility models (MSID and MSNID), an empirical model for ternary systems (EM), a linear mixing model based on mole fractions (LMMM), and a newly developed linear mixing model based on volume fractions of organic mixtures (LMMV) for higher order systems. The two ideal models (MLID and MSID) fit ternary systems of chlorinated organic compounds without surface active compounds relatively well. However, both ideal models did not perform well for the mixtures containing a surface active compound. However, for these systems, both the MLNID and MSNID models matched the IFT data well. It is shown that the MLNID model with a surface coverage value (0.00341 mmol/m2) obtained in this study can practically be used for chlorinated organic compounds. The LMMM results in poorer estimates of the IFT as the difference in IFT values of individual organic compounds in a mixture increases. The EM, with two fitting parameters, provided accurate results for all 14 ternary systems including composite organic compounds. The new LMMV method for quaternary and higher component systems was successfully tested. This study shows that the LMMV may be able to be used for higher component systems and it can be easily incorporated into compositional multiphase flow models using only parameters from ternary systems.

Yoon, Hongkyu; Oostrom, Martinus; Werth, Charles J.

2009-10-15

413

Seasonally-Active Water on Mars: Vapour, Ice, Adsorbate, and the Possibility of Liquid  

NASA Astrophysics Data System (ADS)

Seasonally-active water can be defined to include any water reservoir that communicates with other reservoirs on time scales of a year or shorter. It is the interaction of these water reservoirs, under the influence of varying solar radiation and in conjunction with surface and atmospheric temperatures, that determines the phase-stability field for water at the surface, and the distribution of water in various forms below, on, and above the surface. The atmosphere is the critical, dynamical link in this cycling system, and also (fortunately) one of the easiest to observe. Viking and Mars Global Surveyor observations paint a strongly asymmetric picture of the global seasonal water cycle, tied proximately to planetary eccentricity, and the existence of residual ice caps of different composition at the two poles. The northern summer experiences the largest water vapour columns, and is associated with sublimation from the northern residual water ice cap. The southern summer residual carbon dioxide ice cap is cold trap for water. Asymmetry in the water cycle is an unsolved problem. Possible solutions may involve the current timing of perihelion (the water cap resides at the pole experiencing the longer but cooler summer), the trapping of water ice in the northern hemisphere by tropical water ice clouds, and the bias in the annual-average, zonal-mean atmospheric circulation resulting from the zonal-mean difference in the elevation of the northern and southern hemispheres. Adsorbed and frozen water have proven harder to constrain. Recent Odyssey Gamma Ray Spectrometer results suggest substantial ground ice in the mid- and high-latitudes, but this water is likely below the seasonal skin depth for two reasons: the GRS results are best fit with such a model, and GCM models of the water cycle produce dramatically unrealistic atmospheric vapour distributions when such a very near surface, GRS-like distribution is initialized - ultimately removing the water to the northern and southern caps. Similar climate-models of the water cycle also do not need much exchangeable adsorbed water in order to explain the observed vapour distributions. The possibility of liquid water is tantalizing, but difficult to definitively judge. On scales greater than a meter or so, Mars is most definitely well away from the water triple point--although the surface pressure can exceed 6.1 mbars, the partial pressure of water vapor (to which the triple point refers) is at best orders of magnitude lower. Several careful studies have shown, however, that locally transient (meta-stable) liquid is possible, if the net heating of ice deposits is high enough. This process is aided if the total surface pressure exceeds 6.1mbar (this prevents boiling, or the explosive loss of vapour into the atmosphere) or if the liquid is covered by a thin ice shell, and is only possible if surface temperatures exceed 273K (for pure water, or the appropriate eutectic for brines) and if ice is present. The former challenge is much easier to meet than the latter. The melt scenario requires that ice deposited in winter must be protected from sublimation as surface temperatures increase in spring, but then exposed to the peak of solar heating in summer. Available spacecraft observations of seasonal water will be discussed with the aid of GCM model simulations, and examined in the context of water distributions and phases.

Richardson, M. I.

2002-12-01

414

Predicting water’s phase diagram and liquid-state anomalies  

Microsoft Academic Search

Water expands upon freezing, has minima in its volume, heat capacity, and isothermal compressibility with temperature, and shows signs of a first-order phase transition when supercooled. We present an analytical molecular theory that can account for these behaviors. It suggests that local network formation and hydrogen-bonding cooperativity between triplets of neighboring molecules are keys to understanding water’s thermodynamics.

Thomas M. Truskett; Ken A. Dill

2002-01-01

415

Ionic liquids as mobile phase additives for the high-performance liquid chromatographic analysis of fluoroquinolone antibiotics in water samples.  

PubMed

In this work, four ionic liquids differing in the length of the alkyl chain on the imidazolium cation and one ionic liquid containing tetraethylammonium, all with the same counterion, (i.e. 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIm-BF(4)), 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF(4)), 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIm-BF(4)), 1-methyl-3-octylimidazolium tetrafluoroborate (MOIm-BF(4)), and tetraethylammonium tetrafluroborate (Et(4)N-BF(4))) were tested as mobile phase additives for HPLC separation of a group of seven basic fluoroquinolone (FQ) antibiotics for human and veterinary use (i.e. fleroxacin, ciprofloxacin, lomefloxacin, danofloxacin, enrofloxacin, sarafloxacin, and difloxacin) using a conventional reversed-phase Nova-Pak C(18) column. Fluorescence detection was used. Among the ionic liquids selected, use of BMIm-BF(4) enabled effective separation of these compounds with relatively low analysis time (14 min). The best separation was achieved by isocratic elution at 1 mL min(-1) with 5 mmol L(-1) BMIm-BF(4) and 10 mmol L(-1) ammonium acetate at pH 3.0 with 13% (v/v) acetonitrile. Limits of detection (LODs) for fluorescence detection were in the range 0.5-11 microg L(-1). The method was tested by analyzing several water samples after the optimization of a suitable solid-phase extraction (SPE) procedure using Oasis HLB cartridges. Mean recovery values were above 84% for all analytes with LODs in the range 1-29 ng L(-1). PMID:18854988

Herrera-Herrera, Antonio V; Hernández-Borges, Javier; Rodríguez-Delgado, Miguel Angel

2008-10-15

416

Molecular Mechanism of Transporting a Polarizable Iodide Anion Across the Water-CCl4 Liquid/Liquid Interface  

SciTech Connect

The result of transferring a polarizable iodide anion across the H2O-CCl4 liquid/liquid interface was investigated. The computed transfer free energy profile or potential of mean force exhibits a minimum near the Gibbs dividing surface, and its characteristics are similar to those of found in a corresponding water vapor/liquid interface study involving a smaller minimum free energy. Molecular dynamics simulations also were carried out to compare the concentrations of NaCl, NaBr, and NaI at H2O-vapor and H2O-CCl4 interfaces. While the concentration of bromide and iodide ions were lower at the H2O-CCl4 interface when compared to the H2O-vapor interface, the chloride ion concentrations were similar at both interfaces. Analysis of the solvation structures of iodide and chloride ions revealed that the more polarizable iodide ion was less solvated than the chloride ion at the interface. This characteristic brought the iodide ion in greater contact with CCl4 than the chloride ion, resulting in repulsive interactions with CCl4, which reduced its propensity for the interface. This work was performed at the Pacific Northwest National Laboratory (PNNL) and was supported by the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy (DOE). PNNL is operated by Battelle for the DOE. The DOE Division of Chemical Sciences and the Scientific Computing Staff, Office of Science provided computer resources at the National Energy Research Supercomputer Center (Berkeley, California) that supported this research.

Wick, Collin D.; Dang, Liem X.

2007-04-07

417

theoretical calculation of the coefficient of viscosity of water by non-equilibrium statistical mechanics of simple liquid  

Microsoft Academic Search

The liquid state, especially water, has long been regarded as the most formidable problem in the field of statistical mechanics.\\u000a The coefficient of viscosity of water is calculated using a simplified model based on the microstructure of water and methods\\u000a similar to that used by Rice et al. (1961) who studied the non-equilibrium statistical mechanics of simple liquids, such as

Shu-Bin Ma; Ye-Li Yuan

1994-01-01

418

Unified description of temperature-dependent hydrogen-bond rearrangements in liquid water.  

PubMed

The unique chemical and physical properties of liquid water are a direct result of its highly directional hydrogen-bond (HB) network structure and associated dynamics. However, despite intense experimental and theoretical scrutiny spanning more than four decades, a coherent description of this HB network remains elusive. The essential question of whether continuum or multicomponent ("intact," "broken bond," etc.) models best describe the HB interactions in liquid water has engendered particularly intense discussion. Most notably, the temperature dependence of water's Raman spectrum has long been considered to be among the strongest evidence for a multicomponent distribution. Using a combined experimental and theoretical approach, we show here that many of the features of the Raman spectrum that are considered to be hallmarks of a multistate system, including the asymmetric band profile, the isosbestic (temperature invariant) point, and van't Hoff behavior, actually result from a continuous distribution. Furthermore, the excellent agreement between our newly remeasured Raman spectra and our model system further supports the locally tetrahedral description of liquid water, which has recently been called into question. PMID:16179387

Smith, Jared D; Cappa, Christopher D; Wilson, Kevin R; Cohen, Ronald C; Geissler, Phillip L; Saykally, Richard J

2005-09-22

419

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

NASA Astrophysics Data System (ADS)

The rate of uptake of NO2 by liquid water according to (R1), 2NO2(g) + H2O(1) ? 2H+ + NO3- + NO2-, is shown to be unaffected by O2 (0.2 atm). Hence the rate constant and Henry's law solubility constant of NO2 previously obtained may be employed to evaluate the rates of aqueous phase reactions of NO2 in the ambient atmosphere. Reactions (R1) and (R2), NO2(g) + NO(g) + H2O(1) ? 2H+ + 2NO2-, are quite slow at representative atmospheric partial pressures and cloud liquid water content; the characteristic times range upward from 103-104 hours at 10-7 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 10-7 M, assuming sufficiently fast rate constants (˜108 M-l s-1). Iron-catalyzed reaction in particular, however, is found to be unimportant. Reaction of NO2 with dissolved S(IV) is potentially mportant, based upon an assumed upper limit rate constant of 2.5×107 M-1 s-1. Deposition of NO2 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, Yin-Nan; Schwartz, Stephen E.

1981-12-01

420

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

421

Restriction Fragment Length Polymorphisms Associated with Water Use Efficiency in Tomato  

Microsoft Academic Search

Improvement of crop water use efficiency (WUE) has not been successful because evaluation for this component of drought resistance is unreliable in field-grown plants. The composition of stable isotopes of plant carbon (delta 13C) was earlier shown to be an excellent indicator of WUE in tomato and other species. It is now reported that delta 13C can be satisfactorily predicted

Bjorn Martin; James Nienhuis; Gretchen King; Alison Schaefer

1989-01-01

422

Capillary filling with giant liquid/solid slip: dynamics of water uptake by carbon nanotubes.  

PubMed

This article discusses the way the standard description of capillary filling dynamics has to be modified to account for liquid/solid slip in nanometric pores. It focuses, in particular, on the case of a large slip length compared to the pore size. It is shown that the liquid viscosity does not play a role, and that the flow is only controlled by the friction coefficient of the liquid at the wall. Moreover, in the Washburn regime, the filling velocity does not depend on the tube radius. Finally, molecular dynamics simulations suggest that this standard description fails to describe the early stage of capillary filling of carbon nanotubes by water, since viscous dissipation at the tube entrance must be taken into account. PMID:22149809

Joly, Laurent

2011-12-01

423

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

2011-04-20

424

Decomposition behavior of hemicellulose and lignin in the step-change flow rate liquid hot water.  

PubMed

Hemicellulose and lignin are the main factors limiting accessibility of hydrolytic enzymes besides the crystallinity of cellulose. The decomposition behavior of hemicellulose and lignin in the step-change flow rate hot water system was investigated. Xylan removal increased from 64.53% for batch system (solid concentration 4.25% w/v, 18 min, 184°C) to 83.78% at high flow rates of 30 ml/min for 8 min, and then 10 ml/min for 10 min. Most of them (80-90%) were recovered as oligosaccharide. It was hypothesized that the flowing water could enhance the mass transfer to improve the sugars recovery. In addition, the solubilization mechanism of lignin in the liquid hot water was proposed according to the results of Fourier transform-infrared spectroscopy and scanning electron microscopy of the water-insoluble fraction and gas chromatography-mass spectrometry of the water-soluble fraction. It was proposed that lignin in the liquid hot water first migrated out of the cell wall in the form of molten bodies, and then flushed out of the reactor. A small quantity of them was further degraded into monomeric products such as vanillin, syringe aldehyde, coniferyl aldehyde, ferulic acid, and p-hydroxy-cinnamic acid. All of these observations would provide important information for the downstream processing, such as purification and concentration of sugars and the enzymatic digestion of residual solid. PMID:22270547

Zhuang, Xinshu; Yu, Qiang; Wang, Wen; Qi, Wei; Wang, Qiong; Tan, Xuesong; Yuan, Zhenhong

2012-01-22