WorldWideScience

Sample records for supercooled water involving

  1. Thermal conductivity of supercooled water.

    Science.gov (United States)

    Biddle, John W; Holten, Vincent; Sengers, Jan V; Anisimov, Mikhail A

    2013-04-01

    The heat capacity of supercooled water, measured down to -37°C, shows an anomalous increase as temperature decreases. The thermal diffusivity, i.e., the ratio of the thermal conductivity and the heat capacity per unit volume, shows a decrease. These anomalies may be associated with a hypothesized liquid-liquid critical point in supercooled water below the line of homogeneous nucleation. However, while the thermal conductivity is known to diverge at the vapor-liquid critical point due to critical density fluctuations, the thermal conductivity of supercooled water, calculated as the product of thermal diffusivity and heat capacity, does not show any sign of such an anomaly. We have used mode-coupling theory to investigate the possible effect of critical fluctuations on the thermal conductivity of supercooled water and found that indeed any critical thermal-conductivity enhancement would be too small to be measurable at experimentally accessible temperatures. Moreover, the behavior of thermal conductivity can be explained by the observed anomalies of the thermodynamic properties. In particular, we show that thermal conductivity should go through a minimum when temperature is decreased, as Kumar and Stanley observed in the TIP5P model of water. We discuss physical reasons for the striking difference between the behavior of thermal conductivity in water near the vapor-liquid and liquid-liquid critical points.

  2. Thermodynamic geometry of supercooled water

    Science.gov (United States)

    May, Helge-Otmar; Mausbach, Peter; Ruppeiner, George

    2015-03-01

    The thermodynamic curvature scalar R is evaluated for supercooled water with a two-state equation of state correlated with the most recent available experimental data. This model assumes a liquid-liquid critical point. Our investigation extends the understanding of the thermodynamic behavior of R considerably. We show that R diverges to -∞ when approaching the assumed liquid-liquid critical point. This limit is consistent with all of the fluid critical point models known so far. In addition, we demonstrate a sign change of R along the liquid-liquid line from negative near the critical point to positive on moving away from the critical point in the low density "ice-like" liquid phase. We also trace out the Widom line in phase space. In addition, we investigate increasing correlation length in supercooled water and compare our results with recent published small angle x-ray scattering measurements.

  3. Dynamics of deeply supercooled interfacial water.

    Science.gov (United States)

    Swenson, Jan; Cerveny, Silvina

    2015-01-28

    In this review we discuss the relaxation dynamics of glassy and deeply supercooled water in different types of systems. We compare the dynamics of such interfacial water in ordinary aqueous solutions, hard confinements and biological soft materials. In all these types of systems the dielectric relaxation time of the main water process exhibits a dynamic crossover from a high-temperature non-Arrhenius temperature dependence to a low-temperature Arrhenius behavior. Moreover, at large enough water content the low-temperature process is universal and exhibits the same temperature behavior in all types of systems. However, the physical nature of the dynamic crossover is somewhat different for the different types of systems. In ordinary aqueous solutions it is not even a proper dynamic crossover, since the water relaxation decouples from the cooperative α-relaxation of the solution slightly above the glass transition in the same way as all secondary (β) relaxations of glass-forming materials. In hard confinements, the physical origin of the dynamic crossover is not fully clear, but it seems to occur when the cooperative main relaxation of water at high temperatures reaches a temperature where the volume required for its cooperative motion exceeds the size of the geometrically-confined water cluster. Due to this confinement effect the α-like main relaxation of the confined water seems to transform to a more local β-relaxation with decreasing temperature. Since this low-temperature β-relaxation is universal for all systems at high water content it is possible that it can be considered as an intrinsic β-relaxation of supercooled water, including supercooled bulk water. This possibility, together with other findings for deeply supercooled interfacial water, suggests that the most accepted relaxation scenarios for supercooled bulk water have to be altered.

  4. Thermodynamics and dynamics of supercooled water

    Science.gov (United States)

    Mazza, Marco G.

    This thesis employs methods of statistical mechanics and numerical simulations to study some aspects of the thermodynamic and dynamic behavior of liquid water. As liquid water is cooled down into the supercooled state, some regions of the sample show correlated molecular motion. Previously, only the translational motion has been the object of investigation. Given the importance of orientational dynamics for water, a question that naturally arises is whether the rotational molecular motion also shows heterogeneous dynamics. We show that the most rotationally mobile molecules tend to form clusters, "rotational heterogeneities", and we study their dependence upon observation time and temperature. Further, we show evidence that molecules belonging to dynamic heterogeneities are involved in bifurcated bonds. Since the presence of dynamic heterogeneities is increasingly important as the temperature is lowered, one would expect a signature of this phenomenon in dynamical quantities. We study the effect of dynamic heterogeneities on the origin of the breakdown of the Stokes--- Einstein and Stokes---Einstein---Debye relations for water. These relations link the diffusivity to temperature and viscosity. We study the separation of time scales of dynamic heterogeneities and the diffusive regime. We also consider different sets of mobility, slowest and fastest, for both translational and rotational heterogeneities. A long-standing problem in biology is the seemingly universal loss of biological activity of all biomolecules, a phenomenon termed the "protein glass transition". We explore the connection between the hypothesized liquid-liquid phase transition of water, and the protein glass transition. We find that the protein glass transition coincides with the crossing of the Widom line of hydration water. Many different scenarios have been proposed to rationalize water's thermodynamic anomalies. We study a tell model for water using the Wolff' cluster algorithm, which permits

  5. Transport properties of supercooled confined water

    Science.gov (United States)

    Mallamace, F.; Branca, C.; Broccio, M.; Corsaro, C.; Gonzalez-Segredo, N.; Spooren, J.; Stanley, H. E.; Chen, S.-H.

    2008-07-01

    This article presents an overview of recent experiments performed on transport properties of water in the deeply supercooled region, a temperature region of fundamental importance in the science of water. We report data of nuclear magnetic resonance, quasi-elastic neutron scattering, Fourier-transform infrared spectroscopy, and Raman spectroscopy, studying water confined in nanometer-scale environments. When contained within small pores, water does not crystallise, and can be supercooled well below its homogeneous nucleation temperature Th. On this basis it is possible to carry out a careful analysis of the well known thermodynamical anomalies of water. Studying the temperature and pressure dependencies of water dynamics, we show that the liquid-liquid phase transition (LLPT) hypothesis represents a reliable model for describing liquid water. In this model, water in the liquid state is a mixture of two different local structures, characterised by different densities, namely the low density liquid (LDL) and the high-density liquid (HDL). The LLPT line should terminate at a special transition point: a low-T liquid-liquid critical point. We discuss the following experimental findings on liquid water: (i) a crossover from non-Arrhenius behaviour at high T to Arrhenius behaviour at low T in transport parameters; (ii) a breakdown of the Stokes-Einstein relation; (iii) the existence of a Widom line, which is the locus of points corresponding to maximum correlation length in the p-T phase diagram and which ends in the liquid-liquid critical point; (iv) the direct observation of the LDL phase; (v) a minimum in the density at approximately 70 K below the temperature of the density maximum. In our opinion these results represent the experimental proofs of the validity of the LLPT hypothesis.

  6. Liquid-liquid transition in supercooled aqueous solution involving a low-temperature phase similar to low-density amorphous water

    CERN Document Server

    Woutersen, Sander; Zhao, Zuofeng; Angell, C Austen

    2016-01-01

    The striking anomalies in physical properties of supercooled water that were discovered in the 1960-70s, remain incompletely understood and so provide both a source of controversy amongst theoreticians, and a stimulus to experimentalists and simulators to find new ways of penetrating the "crystallization curtain" that effectively shields the problem from solution. Recently a new door on the problem was opened by showing that, in ideal solutions, made using ionic liquid solutes, water anomalies are not destroyed as earlier found for common salt and most molecular solutes, but instead are enhanced to the point of precipitating an apparently first order liquid-liquid transition. The evidence was a spike in apparent heat capacity during cooling that could be fully reversed during reheating before any sign of ice crystallization appeared. Here, we use decoupled-oscillator infrared spectroscopy to define the structural character of this phenomenon using similar down and upscan rates as in the calorimetric study. Th...

  7. Entropy-driven liquid-liquid separation in supercooled water

    OpenAIRE

    Holten, V.; Anisimov, M.A.

    2012-01-01

    Twenty years ago Poole et al. (Nature 360, 324, 1992) suggested that the anomalous properties of supercooled water may be caused by a critical point that terminates a line of liquid-liquid separation of lower-density and higher-density water. Here we present an explicit thermodynamic model based on this hypothesis, which describes all available experimental data for supercooled water with better quality and with fewer adjustable parameters than any other model suggested so far. Liquid water a...

  8. Supercooled water in austral summer in Prydz Bay,Antarctica

    Institute of Scientific and Technical Information of China (English)

    SHI Jiuxin; CHENG Yaoyao; JIAO Yutian; HOU Jiaqiang

    2011-01-01

    Supercooled water with temperatures below freezing point, was identified from hydrographic data obtained by Chinese and Australian expeditions to Prydz Bay, Antarctica, during the austral summer. The study shows that most supercooled waters occurred at depths of 63-271 m in the region north of the Amery Ice Shelf (AIS) front. The maximum supercooling was 0.16℃ below the in-situ freezing point. In temperature and salinity ranges of-2.14 - -1.96℃ and 34.39--34.46, respectively,the water was colder and fresher than peripheral shelf water. The supercooled water had less variability in the vertical profiles compared to shelf water. Based on analysis of their thermohaline features and spatial distribution, as well as the circulation pattern in Prydz Bay, we conclude that these supercooled waters originated from a cavity beneath the AIS and resulted from upwelling just outside of the AIS front. Water emerging from the ice shelf cools to an extremely low temperature (about -2.0℃) by additional cooling from the ice shelf, and becomes buoyant with the addition of melt water from the ice shelf base. When this water flows out of the ice shelf front, its upper boundary is removed, and thus it rises abruptly. Once the temperature of this water reaches below the freezing point, supercooling takes place. In summer, the seasonal pycnocline at ~100 m water depth acts as a barrier to upwelling and supercooling. The upwelling of ice shelf outflow water illuminates a unique mid-depth convection of the polar ocean.

  9. Polarized View of Supercooled Liquid Water Clouds

    Science.gov (United States)

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

    2016-01-01

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

  10. Polarized View of Supercooled Liquid Water Clouds

    Science.gov (United States)

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

    2016-01-01

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

  11. Peculiar thermodynamics of the second critical point in supercooled water.

    Science.gov (United States)

    Bertrand, C E; Anisimov, M A

    2011-12-08

    On the basis of the principle of critical-point universality, we examine the peculiar thermodynamics of the liquid-liquid critical point in supercooled water. We show that the liquid-liquid criticality in water represents a special kind of critical behavior in fluids, intermediate between two limiting cases: the lattice gas, commonly used to model liquid-vapor transitions, and the lattice liquid, a weakly compressible liquid with an entropy-driven phase separation. While the ordering field in the lattice gas is associated with the chemical potential and the order parameter with the density, in the lattice liquid the ordering field is the temperature and the order parameter is the entropy. The behavior of supercooled water is much closer to lattice-liquid behavior than to lattice-gas behavior. Using new experimental data recently obtained by Mishima [J. Chem. Phys. 2010, 133, 144503], we have revised the parametric scaled equation of state, previously suggested by Fuentevilla and Anisimov [Phys. Rev. Lett. 2006, 97, 195702], and obtain a consistent description of the thermodynamic anomalies of supercooled water by adjusting linear backgrounds, one critical amplitude, and the critical pressure. We also show how the lattice-liquid description affects the finite-size scaling description of supercooled water in confined media.

  12. Volume analysis of supercooled water under high pressure

    OpenAIRE

    Duki, Solomon F.; Tsige, Mesfin

    2016-01-01

    Motivated by recent experimental findings on the volume of supercooled water at high pressure [O. Mishima, J. Chem. Phys. 133, 144503 (2010)] we performed atomistic molecular dynamics simulations study of bulk water in the isothermal-isobaric ensemble. Cooling and heating cycles at different isobars and isothermal compression at different temperatures are performed on the water sample with pressures that range from 0 to 1.0 GPa. The cooling simulations are done at temperatures that range from...

  13. Effects of PVA(Polyvinyl Alcohol) on Supercooling Phenomena of Water

    Science.gov (United States)

    Kumano, Hiroyuki; Saito, Akio; Okawa, Seiji; Takizawa, Hiroshi

    In this paper, effects of polymer additive on supercooling of water were investigated experimentally. Poly-vinyl alcohol (PVA) were used as the polymer, and the samples were prepared by dissolving PVA in ultra pure water. Concentration, degree of polymerization and saponification of PVA were varied as the experimental parameters. The sample was cooled, and the temperature at the instant when ice appears was measured. Since freezing of supercooled water is statistical phenomenon, many experiments were carried out and average degrees of supercooling were obtained for each experimental condition. As the result, it was found that PVA affects nucleation of supercooling and the degree of supercooling increases by adding the PVA. Especially, it is found that the average degree of supercooling increases and the standard deviation of average degree of supercooling decreases with increase of degree of saponification of PVA. However, the average degree of supercooling are independent of the degree of polymerization of PVA in the range of this study.

  14. Slow dynamics of supercooled water confined in nanoporous silica materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, L [Department of Nuclear Engineering, 24-209 MIT, Cambridge, MA 02139 (United States); Faraone, A [Department of Nuclear Engineering, 24-209 MIT, Cambridge, MA 02139 (United States); Mou, C-Y [Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan (China); Yen, C-W [Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan (China); Chen, S-H [Department of Nuclear Engineering, 24-209 MIT, Cambridge, MA 02139 (United States)

    2004-11-17

    We review our incoherent quasielastic neutron scattering (QENS) studies of the dynamics of supercooled water confined in nanoporous silica materials. QENS data were analysed by using the relaxing cage model (RCM) previously developed by us. We first use molecular dynamics (MD) simulation of the extended simple point charge model (SPC/E) for bulk supercooled water to establish the validity of the RCM, which applies to both the translational and rotational motion of water molecules. We then assume that the dynamics of water molecules in the vicinity of a hydrophilic surface is similar to a bulk water at an equivalent lower supercooled temperature. This analogy was experimentally demonstrated in previous investigations of water in Vycor glasses and near hydrophilic protein surfaces. Studies were made of supercooled water in MCM-41-S (pore sizes 25, 18, and 14 A) and MCM-48-S (pore size 22 A) using three QENS spectrometers of respective energy resolutions 1, 30, and 60 {mu}eV, covering the temperature range from 325 to 200 K. Five quantities are extracted from the analysis: they are {beta}, the stretch exponent characterizing the {alpha}-relaxation; {beta}{gamma}, the exponent determining the power-law dependence of the relaxation time on Q; <{tau}{sub 0}>, the Q-independent pre-factor for the average translational relaxation time; <{tau}{sub R{sub 1}}>, the relaxation time for the first-order rotational correlation function; and <{tau}{sub R{sub 3}}>, the relaxation time for the second-order rotational correlation function. We discuss the temperature dependence of these parameters and note that, in particular, the dynamics is rapidly slowing down at temperature around 220 K, signalling the onset of a structural arrest transition of liquid water into an amorphous solid water.

  15. Effects of poly-vinyl alcohol on supercooling phenomena of water

    Energy Technology Data Exchange (ETDEWEB)

    Kumano, Hiroyuki; Hirata, Tetsuo; Kudoh, Tomoya [Department of Mechanical Systems Engineering, Shinshu University, 4-17-1, Wakasato, Nagano City, 380-8553 (Japan)

    2009-05-15

    The effects of a polymer additive on the supercooling of water were investigated experimentally. Poly-vinyl alcohols (PVAs) were used as the additives, and samples were prepared by dissolving the PVA in water. Since the characteristics of PVA are decided by its degrees of polymerization and saponification, these were varied along with the concentration as the experimental parameters. Moreover, the effect of purity of the water was also considered. Each sample was cooled and the temperature at the instant when ice appeared was measured. Since the freezing of supercooled water is a statistical phenomenon, many experiments were carried out and the average degree of supercooling was obtained. It was found that PVA affects the nucleation of ice in supercooled water and the degree of supercooling increases with the addition of PVA even for water with low purity. The average degree of supercooling increases with an increase in the degree of saponification of PVA. (author)

  16. Entropy-driven liquid-liquid separation in supercooled water

    CERN Document Server

    Holten, V

    2012-01-01

    Twenty years ago Poole et al. (Nature 360, 324, 1992) suggested that the anomalous properties of supercooled water may be caused by a critical point that terminates a line of liquid-liquid separation of lower-density and higher-density water. Here we present an explicit thermodynamic model based on this hypothesis, which describes all available experimental data for supercooled water with better quality and with fewer adjustable parameters than any other model suggested so far. Liquid water at low temperatures is viewed as an 'athermal solution' of two molecular structures with different entropies and densities. Alternatively to popular models for water, in which the liquid-liquid separation is driven by energy, the phase separation in the athermal two-state water is driven by entropy upon increasing the pressure, while the critical temperature is defined by the 'reaction' equilibrium constant. In particular, the model predicts the location of density maxima at the locus of a near-constant fraction (about 0.1...

  17. Dynamical properties of confined supercooled water: an NMR study

    Science.gov (United States)

    Mallamace, Francesco; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li; Mou, Chung-Yuan; Chen, Sow-Hsin

    2006-09-01

    We report a set of dynamical data of confined water measured in a very deeply supercooled regime (290-190 K). Water is contained in silica matrices (MCM-41-S) which consist of 1D cylindrical pores with diameters d = 14,18 and 24 Å. When confined in these tubular pores, water does not crystallize, and can be supercooled well below 200 K. We use the NMR technique to obtain the characteristic proton relaxation time-constants (the spin-lattice relaxation time-constant T1 and the spin-spin relaxation time-constant T2) and a direct measurement of the self-diffusion coefficient in the whole temperature range. We give evidence of the existence of a fragile-to-strong dynamic crossover (FSC) at TL = 225 K from the temperature dependence of the self-diffusion coefficient. A combination of the NMR self-diffusion coefficient with the average translational relaxation time, as measured by quasi-elastic neutron scattering, shows a well defined decoupling of transport coefficients, i.e. the breakdown of the Stokes-Einstein relation, on approaching the crossover temperature TL.

  18. Dynamical properties of confined supercooled water: an NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Broccio, Matteo [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Corsaro, Carmelo [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Faraone, Antonio [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Liu Li [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Mou, C-Y [Department of Chemistry, National Taiwan University, Taipei, Taiwan (China); Chen, S-H [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2006-09-13

    We report a set of dynamical data of confined water measured in a very deeply supercooled regime (290-190 K). Water is contained in silica matrices (MCM-41-S) which consist of 1D cylindrical pores with diameters d = 14,18 and 24 A. When confined in these tubular pores, water does not crystallize, and can be supercooled well below 200 K. We use the NMR technique to obtain the characteristic proton relaxation time-constants (the spin-lattice relaxation time-constant T1 and the spin-spin relaxation time-constant T2) and a direct measurement of the self-diffusion coefficient in the whole temperature range. We give evidence of the existence of a fragile-to-strong dynamic crossover (FSC) at T{sub L} = 225 K from the temperature dependence of the self-diffusion coefficient. A combination of the NMR self-diffusion coefficient with the average translational relaxation time, as measured by quasi-elastic neutron scattering, shows a well defined decoupling of transport coefficients, i.e. the breakdown of the Stokes-Einstein relation, on approaching the crossover temperature T{sub L}.

  19. Hydrodynamic states in water below the temperature of the density maximum: the limit to supercooling

    NARCIS (Netherlands)

    van der Elsken, J.; van Boom, L.; Bot, A.

    1988-01-01

    Spectra of fluctuations in the total intensity of laser light deflected by supercooled water show that even under carefully controlled conditions large samples give convection when cooled below -0%. This is in agreement with the Rayleigh versus Prandtlnumber relation for supercooled water.

  20. A molecular dynamics study on surface properties of supercooled water

    Institute of Scientific and Technical Information of China (English)

    L(U) Yongjun; WEI Bingbo

    2006-01-01

    Molecular dynamics simulations were performed to study the surface properties of water in a temperature range from 228 to 293 K by using the extended simple point charge (SPC/E) and four-site TIP4P potentials. The calculated surface tension increases with the decrease of temperature, and moreover the slopes of the surface tension-temperature curves show a weak rise below 273 K, whereas no obvious anomalies appear near 228 K, which accords with the previous experiments. Compared with the measured values, the SPC/E potential shows a good agreement, and the TIP4P potential scription of the surface structure of supercooled water for the SPC/E. When simulating the orientational distributions of water molecules near the surface, the SPC/E potential produces higher ordering and larger surface potentials than the TIP4P potential.

  1. Simulation study of water and sugar dynamics in supercooled mixtures

    Science.gov (United States)

    Molinero, Valeria; Cagin, Tahir; Goddard, William A.

    2003-03-01

    Water dynamics in concentrated carbohydrate solutions is of utmost importance in food and pharmaceutical technology, where low water mobility is desirable to slow down chemical degradation and preserve biomolecules. We have studied the microscopic mechanism of water diffusion in binary and polydisperse malto-oligosaccharides and water mixtures by means of molecular dynamics simulations. The computations were performed with a coarse grain model (M3B), derived from atomistic simulations of water and malto-oligosaccharides. The use of the M3B model permits simulations of the order of 0.1 microsecond, thus allowing us to explore water dynamics from the liquid to the deep supercooled regime. The dynamics of water confined in the sugar matrix is slowed down with respect to bulk water. We found that at low moisture content and low temperature, ranslational diffusion of water and glucose rotation proceed through a hopping-diffusion mechanism. Moreover, we found water mobility to be heterogeneous: there is a broad distribution of time scales for different water molecules in the mixtures. We discuss whether there is a relationship between the heterogeneous structure of these mixtures in the sub-nanometer scale and the heterogeneous dynamics of water molecules.

  2. Dynamics of hydrogen bonds in water and consequences for the unusual behaviour of supercooled water

    Indian Academy of Sciences (India)

    José Teixeira

    2008-10-01

    The dynamics of liquid water is evaluated by the coherent quasi-elastic scattering at two different momentum transfers, in order to discriminate hydrogen bond life-time from molecular dynamics. The results indicate a possible issue for the puzzle of the behaviour of supercooled water.

  3. Chosen thermodynamic experiments: depression of the freezing point of water with salt and supercooled water

    OpenAIRE

    Krnc, Katja

    2014-01-01

    The diploma thesis presents two interesting thermodynamic experiments which were executed and described by Joseph Black in 18th Century. These are: depression of the freezing point of water with salt and supercooled water. We meet water in three states of matter in nature: in the state of ice, liquid water, and water steam. Phase crossing from water to ice (and vice versa from ice to water) is done with normal air pressure with the state temperature of 0°C. If we add certain matters to wat...

  4. The water supercooled regime as described by four common water models

    CERN Document Server

    Malaspina, David C; Pereyra, Rodolfo G; Szleifer, Igal; Carignano, Marcelo A

    2013-01-01

    The temperature scale of simple water models in general does not coincide with the natural one. Therefore, in order to make a meaningful evaluation of different water models a temperature rescaling is necessary. In this paper we introduce a rescaling using the melting temperature and the temperature corresponding to the maximum of the heat capacity to evaluate four common water models (TIP4P-Ew, TIP4P-2005, TIP5P-Ew and Six-Sites) in the supercooled regime. Although all the models show the same general qualitative behavior, the TIP5P-Ew appears as the best representation of the supercooled regime when the rescaled temperature is used. We also analyze, using thermodynamic arguments, the critical nucleus size for ice growth. Finally, we speculate on the possible reasons why atomistic models do not usually crystalize while the coarse grained mW model do crystallize.

  5. Radiometric Observations of Supercooled Liquid Water within a Split Front over the Sierra Nevada.

    Science.gov (United States)

    Heggli, Mark F.; Reynolds, David W.

    1985-11-01

    A storm bearing close structural resemblance to a katafront was observed from the ground with microwave radiometry and a vertically pointing Ka-band radar over the Sierra Nevada of California. The onset and duration of supercooled liquid water was determined and matched to a split front model used to describe the synoptic features of a katafront. Results indicate that prior to the passage of the upper front no supercooled liquid water was observed. This portion of the storm provided the deepest cloud and coldest cloud tops. Supercooled liquid water was most prevalent after the upper front passage, and persisted until the suspected surface front passage. The duration of measured supercooled water was 16 hours.This information broadens the knowledge regarding the presence of supercooled liquid water, and thus possible seeding potential, within winter storms so that treatment can be confined to the period of storms amenable to cloud seeding. Future studies may well confirm the ease with which these periods can be predicted on an operational basis in the Sierra Nevada.

  6. Development of seasonal heat storage based on stable supercooling of a sodium acetate water mixture

    DEFF Research Database (Denmark)

    Furbo, Simon; Fan, Jianhua; Andersen, Elsa

    2012-01-01

    A number of heat storage modules for seasonal heat storages based on stable supercooling of a sodium acetate water mixture have been tested by means of experiments in a heat storage test facility. The modules had different volumes and designs. Further, different methods were used to transfer heat....... • The reliability of the supercooling was elucidated for the heat storage modules for different operation conditions. • The reliability of a cooling method used to start solidification of the supercooled sodium acetate water mixture was elucidated. The method is making use of boiling CO2 in a small tank in good...... to and from the sodium acetate water mixture in the modules. By means of the experiments: • The heat exchange capacity rates to and from the sodium acetate water mixture in the heat storage modules were determined for different volume flow rates. • The heat content of the heat storage modules were determined...

  7. Hydrophobic Surfaces: Topography Effects on Wetting by Supercooled Water and Freezing Delay

    DEFF Research Database (Denmark)

    Heydari, Golrokh; Thormann, Esben; Järn, Mikael

    2013-01-01

    Hydrophobicity, and in particular superhydrophobicity, has been extensively considered to promote ice-phobicity. Dynamic contact angle measurements above 0 °C have been widely used to evaluate the water repellency. However, it is the wetting properties of supercooled water at subzero temperatures...

  8. Anomalous dependence of the heat capacity of supercooled water on pressure and temperature

    Directory of Open Access Journals (Sweden)

    I.A. Stepanov

    2014-01-01

    Full Text Available In some papers, dependences of the isobaric heat capacity of water versus pressure and temperature were obtained. It is shown that these dependences contradict both the dependence of heat capacity on temperature for supercooled water, and an important thermodynamic equation for the dependence of heat capacity on pressure. A possible explanation for this contradiction is proposed.

  9. Mechanism of Supercooled Water Droplet Breakup near the Leading Edge of an Airfoil

    Science.gov (United States)

    Veras-Alba, Belen; Palacios, Jose; Vargas, Mario; Ruggeri, Charles; Bartkus, Tadas P.

    2017-01-01

    This work presents the results of an experimental study on supercooled droplet deformation and breakup near the leading edge of an airfoil. The results are compared to prior room temperature droplet deformation results to explore the effects of droplet supercooling. The experiments were conducted in the Adverse Environment Rotor Test Stand (AERTS) at The Pennsylvania State University. An airfoil model placed at the end of the rotor blades mounted onto the hub in the AERTS chamber was moved at speeds ranging between 50 and 80 m/sec. The temperature of the chamber was set at -20°C. A monotonic droplet generator was used to produce droplets that fell from above, perpendicular to the path of the airfoil. The supercooled state of the droplets was determined by measurement of the temperature of the drops at various locations below the droplet generator exit. A temperature prediction code was also used to estimate the temperature of the droplets based on vertical velocity and the distance traveled by droplets from the droplet generator to the airfoil stagnation line. High speed imaging was employed to observe the interaction between the droplets and the airfoil. The high speed imaging provided droplet deformation information as the droplet approached the airfoil near the stagnation line. A tracking software program was used to measure the horizontal and vertical displacement of the droplet against time. It was demonstrated that to compare the effects of water supercooling on droplet deformation, the ratio of the slip velocity and the initial droplet velocity must be equal. A case with equal slip velocity to initial velocity ratios was selected for room temperature and supercooled droplet conditions. The airfoil velocity was 60 m/s and the slip velocity for both sets of data was 40 m/s. In these cases, the deformation of the weakly supercooled and warm droplets did not present different trends. The similar behavior for both environmental conditions indicates that water

  10. Temperature-dependent bouncing of super-cooled water on teflon-coated superhydrophobic tungsten nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Khedir, Khedir R.; Kannarpady, Ganesh K.; Ishihara, Hidetaka; Woo, Justin; Asar, Madhu P. [Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR, 72204 (United States); Ryerson, Charles [Terrestrial and Cryospheric Sciences Branch Cold Regions, Research and Engineering Laboratory, U.S. Army Corps of Engineers, Hanover, NH 03755-1290 (United States); Biris, Alexandru S., E-mail: asbiris@ualr.edu [Center for Integrative Nanotechnology Sciences, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR, 72204 (United States)

    2013-08-15

    The bouncing mechanism of warm and supercooled water droplets with temperatures ranging from 20 °C to −10 °C on the surface of superhydrophobic (SHP) tungsten nanorods (WNRs), held at a constant temperature of −10 °C, was investigated. The measurements were carried out inside a chamber kept at a low relative humidity of 20%. A considerable energy loss was observed mainly due to the increase in the viscous forces of the supercooled water droplet. The increase in the values of the capillary number, as a result of the variation in both viscosity and surface energy of the supercooled water droplet, has confirmed the significant role of viscous forces in the dissipation of bouncing energy. However, the contact time and contact line evolution of the supercooled water droplet on the surface remained unaffected by the decrease in its temperature at constant humidity. The calculations of the bouncing restitution and dissipated energy at various water droplet temperatures, using classical mechanics, were also carried out.

  11. Possible Evidence for a New Form of Liquid Buried in the Surface Tension of Supercooled Water

    Science.gov (United States)

    Rogers, T. Ryan; Leong, Kai-Yang; Wang, Feng

    2016-09-01

    Contrary to the historical data, several recent experiments indicate that the surface tension of supercooled water follows a smooth extrapolation of the IAPWS equation in the supercooled regime. It can be seen, however, that a small deviation from the IAPWS equation is present in the recent experimental measurements. It is shown with simulations using the WAIL water potential that the small deviation in the experimental data is consistent with the tail of an exponential growth in surface tension as temperature decreases. The emergence temperature, Te, of a substantial deviation from the IAPWS equation is shown to be 227 K for the WAIL water and 235 K for real water. Since the 227 K Te is close to the Widom line in WAIL water, we argue that real water at 235 K approaches a similar crossover line at one atmospheric pressure.

  12. Liquid–liquid transition in supercooled water suggested by microsecond simulations

    OpenAIRE

    Li, Yaping; Li, Jicun; Wang, Feng

    2013-01-01

    The putative liquid–liquid phase transition in supercooled water has been used to explain many anomalous behaviors of water. However, no direct experimental verification of such a phase transition has been accomplished, and theoretical studies from different simulations contradict each other. We investigated the putative liquid–liquid phase transition using the Water potential from Adaptive Force Matching for Ice and Liquid (WAIL). The simulation reveals a first-order phase transition in the ...

  13. Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds

    Directory of Open Access Journals (Sweden)

    P. M. Rowe

    2013-07-01

    Full Text Available Simulations of cloud radiative properties for climate modeling and remote sensing rely on accurate knowledge of the complex refractive index (CRI of water. Although conventional algorithms employ a temperature independent assumption (TIA, recent infrared measurements of supercooled water have demonstrated that the CRI becomes increasingly ice-like at lower temperatures. Here, we assess biases that result from ignoring this temperature dependence. We show that TIA-based cloud retrievals introduce spurious ice into pure, supercooled clouds, or underestimate cloud thickness and droplet size. TIA-based downwelling radiative fluxes are lower than those for the temperature-dependent CRI by as much as 1.7 W m−2 (in cold regions, while top-of-atmosphere fluxes are higher by as much as 3.4 W m−2 (in warm regions. Proper accounting of the temperature dependence of the CRI, therefore, leads to significantly greater local greenhouse warming due to supercooled clouds than previously predicted. The current experimental uncertainty in the CRI at low temperatures must be reduced to properly account for supercooled clouds in both climate models and cloud property retrievals.

  14. Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds

    Directory of Open Access Journals (Sweden)

    P. M. Rowe

    2013-12-01

    Full Text Available Simulations of cloud radiative properties for climate modeling and remote sensing rely on accurate knowledge of the complex refractive index (CRI of water. Although conventional algorithms employ a temperature-independent assumption (TIA, recent infrared measurements of supercooled water have demonstrated that the CRI becomes increasingly ice-like at lower temperatures. Here, we assess biases that result from ignoring this temperature dependence. We show that TIA-based cloud retrievals introduce spurious ice into pure, supercooled clouds, or underestimate cloud optical thickness and droplet size. TIA-based downwelling radiative fluxes are lower than those for the temperature-dependent CRI by as much as 1.7 W m−2 (in cold regions, while top-of-atmosphere fluxes are higher by as much as 3.4 W m−2 (in warm regions. Proper accounting of the temperature dependence of the CRI, therefore, leads to significantly greater local greenhouse warming due to supercooled clouds than previously predicted. The current experimental uncertainty in the CRI at low temperatures must be reduced to account for supercooled clouds properly in both climate models and cloud-property retrievals.

  15. Solidification of supercooled water in the vicinity of a solid wall

    Science.gov (United States)

    Schremb, Markus; Tropea, Cameron

    2016-11-01

    An experimental approach utilizing a Hele-Shaw cell for the investigation of the solidification of a supercooled liquid in contact with a solid wall is presented. The setup is based on an idea presented by Marín et al. [A. G. Marín et al., Phys. Rev. Lett. 113, 054301 (2014), 10.1103/PhysRevLett.113.054301], who investigated the planar freezing of a sessile drop without supercooling. This apparatus overcomes optical distortions present when observing the freezing of sessile drops, arising due to reflections and refraction of light on the drop surface. The facility is used to investigate the freezing process of water drops, supercooled down to -20∘C , and to qualitatively demonstrate that the growth behavior is uninfluenced by the use of the Hele-Shaw cell. Different features during freezing, which are known for sessile water drops, are also observed with the Hele-Shaw cell. The growth morphology within the first phase of solidification is categorized according to the initial drop supercooling. Furthermore, freezing velocities within this phase are related to data available in the literature for the growth of single ice dendrites.

  16. Evidence of the existence of the low-density liquid phase in supercooled, confined water

    OpenAIRE

    Mallamace, Francesco; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Majolino, Domenico; Venuti, Valentina; Liu, Li; Mou, Chung-Yuan; Chen, Sow-Hsin

    2006-01-01

    By confining water in a nanoporous structure so narrow that the liquid could not freeze, it is possible to study properties of this previously undescribed system well below its homogeneous nucleation temperature TH = 231 K. Using this trick, we were able to study, by means of a Fourier transform infrared spectroscopy, vibrational spectra (HOH bending and OH-stretching modes) of deeply supercooled water in the temperature range 183 < T < 273 K. We observed, upon decreasing temperature, the bui...

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

    OpenAIRE

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

    2014-01-01

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two...

  18. Unraveling the microscopic pathway of homogeneous water crystallization at supercooled conditions from direct simulations

    Science.gov (United States)

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

    By means of unbiased classical molecular dynamics simulations, we identify the microscopic pathways of spontaneous homogeneous crystallization in supercooled ST2 water. By introducing a new order parameter, we are able to monitor formation/disruption of locally ordered regions characterized by small ice clusters with intermediate range order. When two of these regions are close each other, they percolate and form a larger ordered region. The process is slow enough to allow for polymorphic selection in favor of cubic ice (Ic). The formation of an ice nucleus requires percolation of many small clusters so that the transformations at the interface of the nucleus do not involve its core, thus guaranteeing the stability of the nucleus. The growth of the crystalline nucleus is fast and involves direct transformation of interfacial liquid molecules as well as percolation of small Ic/Ih clusters. The growth is too fast to allow conversion of Ih into Ic sites, originating the formation of a stacking fault in the final crystal. We recognize Euclidean structures in the oxygen configuration of the second shell in Ic and Ih clusters. This new point of view allows us to explain the source of the ordered stacking fault geometry.

  19. The Violation of Stokes-Einstein Relation in Supercooled Water

    OpenAIRE

    Chen, Sow-Hsin; Mallamace, Francesco; Mou, Chung-Yuan; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li

    2006-01-01

    By confining water in nanopores, so narrow that the liquid cannot freeze, it is possible to explore its properties well below its homogeneous nucleation temperature TH ~ 235 K. In particular, the dynamical parameters of water can be measured down to 180 K approaching the suggested glass transition temperature Tg ~ 165 K. Here we present experimental evidence, obtained from Nuclear Magnetic Resonance and Quasi-Elastic Neutron Scattering spectroscopies, of a well defined decoupling of transport...

  20. Evidence of the existence of the low-density liquid phase in supercooled, confined water.

    Science.gov (United States)

    Mallamace, Francesco; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Majolino, Domenico; Venuti, Valentina; Liu, Li; Mou, Chung-Yuan; Chen, Sow-Hsin

    2007-01-09

    By confining water in a nanoporous structure so narrow that the liquid could not freeze, it is possible to study properties of this previously undescribed system well below its homogeneous nucleation temperature TH = 231 K. Using this trick, we were able to study, by means of a Fourier transform infrared spectroscopy, vibrational spectra (HOH bending and OH-stretching modes) of deeply supercooled water in the temperature range 183 < T < 273 K. We observed, upon decreasing temperature, the building up of a new population of hydrogen-bonded oscillators centered around 3,120 cm(-1), the contribution of which progressively dominates the spectra as one enters into the deeply supercooled regime. We determined that the fractional weight of this spectral component reaches 50% just at the temperature, TL approximately 225 K, where the confined water shows a fragile-to-strong dynamic cross-over phenomenon [Ito, K., Moynihan, C. T., Angell, C. A. (1999) Nature 398:492-494]. Furthermore, the fact that the corresponding OH stretching spectral peak position of the low-density-amorphous solid water occurs exactly at 3,120 cm(-1) [Sivakumar, T. C., Rice, S. A., Sceats, M. G. (1978) J. Chem. Phys. 69:3468-3476.] strongly suggests that these oscillators originate from existence of the low-density-liquid phase derived from the occurrence of the first-order liquid-liquid (LL) phase transition and the associated LL critical point in supercooled water proposed earlier by a computer molecular dynamics simulation [Poole, P. H., Sciortino, F., Essmann, U., Stanley, H. E. (1992) Nature 360:324-328].

  1. Liquid-liquid transition in supercooled water suggested by microsecond simulations.

    Science.gov (United States)

    Li, Yaping; Li, Jicun; Wang, Feng

    2013-07-23

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

  2. Optical Kerr effect of liquid and supercooled water: The experimental and data analysis perspective

    Science.gov (United States)

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

    2014-08-01

    The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful experimental tool enabling accurate investigations of the dynamic phenomena in molecular liquids. We introduced innovative experimental and fitting procedures, that enable a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of liquid water. We report OKE data on water measuring intermolecular vibrations and the structural relaxation processes in an extended temperature range, inclusive of the supercooled states. The unpreceded data quality makes possible a solid comparison with few theoretical models: the multi-mode Brownian oscillator model, the Kubo's discrete random jump model, and the schematic mode-coupling model. All these models produce reasonable good fits of the OKE data of stable liquid water, i.e., over the freezing point. The features of water dynamics in the OKE data becomes unambiguous only at lower temperatures, i.e., for water in the metastable supercooled phase. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if its intrinsic hydrodynamic approach does not give a direct access to the molecular information.

  3. Enhanced small-angle scattering connected to the Widom line in simulations of supercooled water.

    Science.gov (United States)

    Wikfeldt, K T; Huang, C; Nilsson, A; Pettersson, L G M

    2011-06-07

    We present extensive simulations on the TIP4P∕2005 water model showing significantly enhanced small-angle scattering (SAS) in the supercooled regime. The SAS is related to the presence of a Widom line (T(W)) characterized by maxima in thermodynamic response functions and Ornstein-Zernike correlation length. Recent experimental small-angle x-ray scattering data [Huang et al., J. Chem. Phys. 133, 134504 (2010)] are excellently reproduced, albeit with an increasing temperature offset at lower temperatures. Assuming the same origin of the SAS in experiment and model this suggests the existence of a Widom line also in real supercooled water. Simulations performed at 1000 bar show an increased abruptness of a crossover from dominating high-density (HDL) to dominating low-density (LDL) liquid and strongly enhanced SAS associated with crossing T(W), consistent with a recent determination of the critical pressure of TIP4P∕2005 at 1350 bar. Furthermore, good agreement with experimental isothermal compressibilities at 1000, 1500, and 2000 bar shows that the high pressure supercooled thermodynamic behavior of water is well described by TIP4P∕2005. Analysis of the tetrahedrality parameter Q reveals that the HDL-LDL structural transition is very sharp at 1000 bar, and that structural fluctuations become strongly coupled to density fluctuations upon approaching T(W). Furthermore, the tetrahedrality distribution becomes bimodal at ambient temperatures, an observation that possibly provides a link between HDL-LDL fluctuations and the structural bimodality in liquid water indicated by x-ray spectroscopic techniques. Computed x-ray absorption spectra are indeed found to show sensitivity to the tetrahedrality parameter.

  4. A molecular dynamics study on surface properties of supercooled water

    Institute of Scientific and Technical Information of China (English)

    Lü; Yongjun

    2006-01-01

    [1]Basu J K,Hazra S,Sanyal M K.Growth mechanism of Langmuir-Blodgett films.Phys Rev Lett,1999,82:4675-4678[2]Taylor R S,Shields R L.Molecular-dynamics simulations of the ethanol liquid-vapor interface.J Chem Phys,2003,119:12569-12576[3]Velev O D,Gurkov T D,Ivanov I B,et al.Abnormal thickness and stability of nonequilibrium liquid films.Phys Rev Lett,1995,75:264-267[4]Weng J G,Park S,Lukes J R,et al.Molecular dynamics investigation of thickness effect on liquid films.J Chem Phys,2000,113:5917-5923[5]Zakharov V V,Brodskaya E N,Laaksonen A.Surface tension of water droplets:A molecular dynamics study of model and size dependencies.J Chem Phys,1997,107:10675-10683[6]Wang J Z,Chen M,Guo Z Y.A two-dimensional molecular dynamics simulation of liquid-vapor nucleation.Chin Sci Bull,2003,48(7):623-626[7]Guissani Y,Guillot B.A computer simulation study of the liquid-vapor coexistence curve of water.J Chem Phys,1993,98:8221-8235[8]Wilson M A,Pohorille A,Pratt L R.Surface potential of the water liquid-vapor interface.J Chem Phys,1988,88:3281-3285[9]Alejandre J,Tildesley D J,Chapela G A.Molecular dynamics simulation of the orthobaric densities and surface tension of water.J Chem Phys,1995,102:4574-4583[10]Matsumoto M,Kataoka Y.Study on liquid-vapor interface of water (Ⅰ):Simulational results of thermodynamic properties and orientational structure.J Chem Phys,1988,88:3233-3245[11]Floriano M A,Angell C A.Surface tension and molar surface free energy and entropy of water to-27.2℃.J Phys Chem,1990,94:4199-4202[12]Jorgensen W L,Chandrasekhar J,Madura J D.Comparison of simple potential functions for simulating liquid water.J Chem Phys,1993,79:926-935[13]Berendsen H J C,Grigera J R,Straatsma T P.The missing term in effective pair potentials.J Phys Chem,1987,91:6269-6271[14]Arbuckle B W,Clancy P.Effects of the Ewald sum on the free energy of the extended simple point charge model for water.J Chem Phys,2002,116:5090-5098[15]Tarazona P,Chacon E,Reinaldo-Falagan M,et al

  5. Wetting hysteresis induced by temperature changes: Supercooled water on hydrophobic surfaces.

    Science.gov (United States)

    Heydari, Golrokh; Sedighi Moghaddam, Maziar; Tuominen, Mikko; Fielden, Matthew; Haapanen, Janne; Mäkelä, Jyrki M; Claesson, Per M

    2016-04-15

    The state and stability of supercooled water on (super)hydrophobic surfaces is crucial for low temperature applications and it will affect anti-icing and de-icing properties. Surface characteristics such as topography and chemistry are expected to affect wetting hysteresis during temperature cycling experiments, and also the freezing delay of supercooled water. We utilized stochastically rough wood surfaces that were further modified to render them hydrophobic or superhydrophobic. Liquid flame spraying (LFS) was utilized to create a multi-scale roughness by depositing titanium dioxide nanoparticles. The coating was subsequently made non-polar by applying a thin plasma polymer layer. As flat reference samples modified silica surfaces with similar chemistries were utilized. With these substrates we test the hypothesis that superhydrophobic surfaces also should retard ice formation. Wetting hysteresis was evaluated using contact angle measurements during a freeze-thaw cycle from room temperature to freezing occurrence at -7°C, and then back to room temperature. Further, the delay in freezing of supercooled water droplets was studied at temperatures of -4°C and -7°C. The hysteresis in contact angle observed during a cooling-heating cycle is found to be small on flat hydrophobic surfaces. However, significant changes in contact angles during a cooling-heating cycle are observed on the rough surfaces, with a higher contact angle observed on cooling compared to during the subsequent heating. Condensation and subsequent frost formation at sub-zero temperatures induce the hysteresis. The freezing delay data show that the flat surface is more efficient in enhancing the freezing delay than the rougher surfaces, which can be rationalized considering heterogeneous nucleation theory. Thus, our data suggests that molecular flat surfaces, rather than rough superhydrophobic surfaces, are beneficial for retarding ice formation under conditions that allow condensation and frost

  6. Dynamically slow processes in supercooled water confined between hydrophobic plates

    Energy Technology Data Exchange (ETDEWEB)

    Franzese, Giancarlo [Departamento de Fisica Fundamental, Universidad de Barcelona, Diagonal 647, Barcelona 08028 (Spain); Santos, Francisco de los, E-mail: gfranzese@ub.ed, E-mail: fdlsant@ugr.e [Departamento de Electromagnetismo y Fisica de la Materia, Universidad de Granada, Fuentenueva s/n, 18071 Granada (Spain)

    2009-12-16

    We study the dynamics of water confined between hydrophobic flat surfaces at low temperature. At different pressures, we observe different behaviors that we understand in terms of the hydrogen bond dynamics. At high pressure, the formation of the open structure of the hydrogen bond network is inhibited and the surfaces can be rapidly dried (dewetted) by formation of a large cavity with decreasing temperature. At lower pressure we observe strong non-exponential behavior of the correlation function, but with no strong increase of the correlation time. This behavior can be associated, on the one hand, to the rapid ordering of the hydrogen bonds that generates heterogeneities and, on the other hand, to the lack of a single timescale as a consequence of the cooperativity in the vicinity of the liquid-liquid critical point that characterizes the phase diagram at low temperature of the water model considered here. At very low pressures, the gradual formation of the hydrogen bond network is responsible for the large increase of the correlation time and, eventually, the dynamical arrest of the system, with a strikingly different dewetting process, characterized by the formation of many small cavities.

  7. Two-Dimensional Nucleation of Ice from Supercooled Water

    Science.gov (United States)

    Seeley, L. H.; Seidler, G. T.

    2001-03-01

    Heterogeneous nucleation is the initial formation of a stable phase from a metastable phase in the presence of a catalyzing surface. This ubiquitous process has consequences ranging from metallurgy to the formation of kidney stones. Heterogeneous nucleation of ice plays a central role in cloud formation, suggesting one possible connection between anthropogenic pollutants and global climate. A key topic in the theory of nucleation is the geometry of the critical nucleus. Standard nucleation theories generally predict a compact critical nucleus with a surface of roughly constant curvature. We report measurements of the temperature dependent nucleation rate of ice from water samples supporting aliphatic alcohol Langmuir films. We use classical nucleation theory to extract thermodynamic parameters from the measured nucleation rates. From these parameters we conclude that both the effective free energy barrier and the molecular kinetics of nucleation are dominated by the physics at the interface. Our results give self-consistent evidence that the geometry of the critical nucleus in this system is essentially two-dimensional.

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

    Science.gov (United States)

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

    2014-08-01

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

  9. Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

    Energy Technology Data Exchange (ETDEWEB)

    Biddle, John W.; Holten, Vincent; Anisimov, Mikhail A., E-mail: anisimov@umd.edu [Institute for Physical Science and Technology and Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742 (United States)

    2014-08-21

    A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid–liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid–liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H{sub 2}O-NaCl and H{sub 2}O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter [J. Phys. Chem. B 104, 8563 (2000)], to be consistent with the presence of the metastable liquid–liquid transition. We elucidate the non-conserved nature of the order parameter (extent of “reaction” between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

  10. Fragile-to-strong crossover in supercooled water: A comparison between TIP4P and TIP4P/2005 models

    Science.gov (United States)

    De Marzio, M.; Camisasca, G.; Rovere, M.; Gallo, P.

    2016-05-01

    We present recent simulation results on the dynamics of supercooled water with the TIP4P/2005 potential. We find that the dynamical behaviour of the translational motion of the molecules is well interpreted in terms of the Mode Coupling Theory, as it was found for supercooled TIP4P water. We compare the results of the two models and in particular we find also in TIP4P/2005 a crossover from a fragile to a strong regime. We connect this crossover to the crossing of the Widom line emanating from the liquid-liquid critical point.

  11. Measuring ice and liquid water content in moderately supercooled clouds with Cloudnet

    Science.gov (United States)

    Bühl, Johannes; Seifert, Patric; Myagkov, Alexander; Albert, Ansmann

    2016-04-01

    The interaction between ice nuclei and clouds is an important topic in weather and climate research. Recent laboratory experiments and field in-situ field campaigns present more and more detailed measurements of ice nucleating particles (INP) at temperatures close to 0°C. This brings moderately supercooled mixed-phase clouds into the focus of current cloud research. One current example is the European Union BACCHUS project. A major goal of BACCHUS is the analysis of the anthropogenic impact on ice nucleation. Within this project, we use the Leipzig Aerosol Cloud Remote Observations System (LACROS) and the Cloudnet framework in order to get quantitative insight into the formation of ice in mixed-phase layered clouds with cloud top temperature (CTT) from -40 to 0°C. Depolarization measurements from lidar and radar show a clear dependence between particle shape and the temperature under which the particles have been formed. The special focus of this work is on the CTT range from -10 to 0°C. An algorithm is presented to decide between ice and liquid water precipitation falling from the clouds showing that between 10% and 30% of all layered clouds show ice precipitation with CTT between -5 and 0°C. For these slightly supercooled clouds an average ice-water-content between 10e-7 and 10e-8 [kg per cubic meter] is found.

  12. Growth rate of crystalline ice and the diffusivity of supercooled water from 126 to 262 K

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-12

    Understanding deeply supercooled water is key to unraveling many of water’s anomalous properties. However, this has proven difficult due to rapid and uncontrolled crystallization. Using a pulsed laser heating technique, we measure the growth rate of crystalline ice, G(T), for 180 K < T < 262 K, i.e. deep within water’s “no man’s land.” The self-diffusion of supercooled liquid water, D(T), is obtained from G(T) using the Wilson-Frenkel model of crystal growth. For T > 237 K, G(T) and D(T) have super-Arrhenius (“fragile”) temperature dependences, but both crossover to Arrhenius (“strong”) behavior with a large activation energy in “no man’s land.” The fact that G(T) and D(T) are smoothly varying rules out the hypothesis that liquid water’s properties have a singularity at or near 228 K. However the results are consistent with a previous prediction for D(T) that assumed no thermodynamic transitions occur in “no man’s land.

  13. Supercooled Water.

    Science.gov (United States)

    1983-03-01

    53) study by Egelstaff et al Emulsion samples have also been briefly studied but background difficulties have made resolution of the results...Angell, L., Angell, C. A. ., Phys. Chem. (to be published) 52. Bosio, L., Chen, S.-H., Teixeira, 3. Phys. Rev. A (in press) 53. Egelstaff , P. A., Polo, 3

  14. Studies of a dynamic type ice storage system using supercooled water; Kareikyakusui riyo dainamikku gata shochikunetsu shisutemu no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Ito, S.; Hashimoto, A.; Miura, N. [Kanagawa Inst. of Tech., Kanagawa (Japan); Ikemoto, Y.

    1999-11-25

    An ice storage system using supercooled water was constructed and the performance was tested. The system was consisted of a storage tank with the volume of 1.2 m{sup 3} in which slurry-ice was stared, a spiral double-tube heat exchanger 22 m long for making supercooled water by brine, a refrigerating machine of the rated capacity of 2.2 kW, reservoirs for cold and hot brine, heaters, and pumps. The system was able to be operated for more than 5 hours without freezing mostly if the degree of supercooling was less than about 2 degree C. The COPs based on the power of the refrigerating machine and system were about 1.3 and 0.7, respectively. (author)

  15. Volume and structural analysis of super-cooled water under high pressure

    Science.gov (United States)

    Duki, Solomon F.; Tsige, Mesfin

    2012-02-01

    Motivated by recent experimental study of super-cooled water at high pressure [1], we performed atomistic molecular dynamic simulations study on bulk water molecules at isothermal-isobaric ensemble. These simulations are performed at temperatures that range from 40 K to 380 K using two different cooling rates, 10K/ns and 10K/5ns, and pressure that ranges from 1atm to 10000 atm. Our analysis for the variation of the volume of the bulk sample against temperature indicates a downward concave shape for pressures above certain values, as reported in [1]. The same downward concave behavior is observed at high pressure on the mean-squared-displacements (MSD) of the water molecules when the MSD is plotted against time. To get further insight on the effect of the pressure on the sample we have also performed a structural analysis of the sample.[4pt] [1] O. Mishima, J. Chem. Phys. 133, 144503 (2010);

  16. Size dependence of volume and surface nucleation rates for homogeneous freezing of supercooled water droplets

    Directory of Open Access Journals (Sweden)

    T. Kuhn

    2009-10-01

    Full Text Available We investigated the relative roles of volume and surface nucleation in the freezing of water droplets. Nucleation experiments were carried out in a cryogenic laminar aerosol flow tube using supercooled liquid water aerosols with radii between about 1 and 3 μ m. Temperature- and size-dependent values of volume- and surface-based homogeneous nucleation rate between 234.8 and 236.2 K are derived with help of a microphysical model from aerosol compositions and size distributions based on infrared extinction measurements in the aerosol flow tube. The results show that the contribution from nucleation at the droplet surface increases with decreasing droplet radius and dominates over nucleation in the bulk droplet volume for droplets with radii smaller than approximately 5 μm. This is interpreted in terms of a lowered free energy of ice germ formation in the surface-based process and has implications for the parameterization of homogeneous ice nucleation in numerical models.

  17. Water and its relatives: the stable, supercooled and particularly the stretched, regimes

    CERN Document Server

    Meadley, Stacey L

    2014-01-01

    While the water molecule is simple, its condensed phase liquid behavior is so complex that no consensus description has emerged despite three centuries of effort. Here we identify features of its behavior that are the most peculiar, hence suggest ways forward. We examine the properties of water at the boundaries of common experience, including stable states at high pressure, the supercooled state at normal and elevated pressure, and the stretched ("negative pressure") state, out to the limits of mechanical stability. The familiar anomalies at moderate pressures (viscosity and density (TMD) behavior, etc.), are not explained by H-bond breaking, according to common bond-breaking criteria. A comparison of data on the TMD, at both positive and negative pressures, with the predictions of popular pair potential models, shows dramatic discrepancies appearing in the stretched liquid domain. This prompts questions on the second critical point (TC2) hypothesis that has been guiding much current thinking. We turn to rel...

  18. Evaporative supercooling characteristics of single water droplet in ice-slurry production system with evaporative supercooled water%蒸发式过冷水制冰中单个水滴的蒸发过冷特性

    Institute of Scientific and Technical Information of China (English)

    闫俊海; 张小松

    2012-01-01

    To analyze the evaporation characteristics of single water droplet in low temperature and low humidity ratio air in ice production system with evaporative supercooled water, a mathematical model of evaporative supercooling process of single water droplet was proposed. The evaporation process of droplet in supercooling stage was simulated with theoretical model and the results are basically consistent with the experiment on suspended single water droplet, so it is feasible to predict the evaporative supercooling characteristics of small water droplet by the mathematical model. The influence of initial diameter and temperature of water droplet, air temperature, humidity ratio of air, and air velocity on the temperature of water droplet during its evaporative supercooling process was analyzed. The numerical results show that smaller diameter and lower temperature of water droplet and larger air velocity can increase the cooling rate of water droplet and shorten the supercooling time reaching steady state evaporation stage. Additionally, lowering the temperature or humidity ratio of air can not only improve the cooling rate of water droplet, but also increase the supercooling degree of water droplet reaching steady state evaporation stage. The investigation of evaporative supercooling process of water droplet can provide a foundation for improving the efficiency of ice production and optimal design for ice-making system with evaporative supercooled water.%为分析蒸发式过冷水制冰中单个水滴在此低温低湿空气环境中的蒸发特性,建立了水滴蒸发过冷过程的数理模型.通过悬挂水滴实验与模拟结果的对比,验证了模型的有效性.因此利用该数学模型预测微小直径水滴的蒸发特性是可行的.通过模拟计算获得了水滴初始直径、初始水温、空气温度、空气含湿量和空气流速对水滴蒸发过冷过程的影响.结果表明,水滴初始直径越小、温度越低或空气流速越大,

  19. Realisation of dynamic ice-making by supercooled water%过冷水动态制冰的研究

    Institute of Scientific and Technical Information of China (English)

    曲凯阳; 江亿

    2001-01-01

    Further studies based on the authors' earlier researches the conditions under which no fpeezing occur in the supercooler while sufficient supercooling of water is guaranteed.Establishes a stably opepeting experimental assembly. Water temperature at the entrance of the supercooler reaches as low as 0.45 ℃, and the water temperature drop in supercooler isabout 1℃.%在作者前期研究的基础上,进一步研究了保证过冷水动态制冰系统中过冷却器不发生结冰的条件,建立了能够稳定运行的过冷水动态制冰实验装置。水在过冷却器入口的最低温度为0.45℃,在过冷却器中的温降约为1.0℃。

  20. Vibrating-Wire, Supercooled Liquid Water Content Sensor Calibration and Characterization Progress

    Science.gov (United States)

    King, Michael C.; Bognar, John A.; Guest, Daniel; Bunt, Fred

    2016-01-01

    NASA conducted a winter 2015 field campaign using weather balloons at the NASA Glenn Research Center to generate a validation database for the NASA Icing Remote Sensing System. The weather balloons carried a specialized, disposable, vibrating-wire sensor to determine supercooled liquid water content aloft. Significant progress has been made to calibrate and characterize these sensors. Calibration testing of the vibrating-wire sensors was carried out in a specially developed, low-speed, icing wind tunnel, and the results were analyzed. The sensor ice accretion behavior was also documented and analyzed. Finally, post-campaign evaluation of the balloon soundings revealed a gradual drift in the sensor data with increasing altitude. This behavior was analyzed and a method to correct for the drift in the data was developed.

  1. Freezing avoidance by supercooling in Olea europaea cultivars: the role of apoplastic water, solute content and cell wall rigidity.

    Science.gov (United States)

    Arias, Nadia S; Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo

    2015-10-01

    Plants can avoid freezing damage by preventing extracellular ice formation below the equilibrium freezing temperature (supercooling). We used Olea europaea cultivars to assess which traits contribute to avoid ice nucleation at sub-zero temperatures. Seasonal leaf water relations, non-structural carbohydrates, nitrogen and tissue damage and ice nucleation temperatures in different plant parts were determined in five cultivars growing in the Patagonian cold desert. Ice seeding in roots occurred at higher temperatures than in stems and leaves. Leaves of cold acclimated cultivars supercooled down to -13 °C, substantially lower than the minimum air temperatures observed in the study site. During winter, leaf ice nucleation and leaf freezing damage (LT50 ) occurred at similar temperatures, typical of plant tissues that supercool. Higher leaf density and cell wall rigidity were observed during winter, consistent with a substantial acclimation to sub-zero temperatures. Larger supercooling capacity and lower LT50 were observed in cold-acclimated cultivars with higher osmotically active solute content, higher tissue elastic adjustments and lower apoplastic water. Irreversible leaf damage was only observed in laboratory experiments at very low temperatures, but not in the field. A comparative analysis of closely related plants avoids phylogenetic independence bias in a comparative study of adaptations to survive low temperatures.

  2. Effects of atmospheric dynamics and aerosols on the fraction of supercooled water clouds

    Science.gov (United States)

    Li, Jiming; Lv, Qiaoyi; Zhang, Min; Wang, Tianhe; Kawamoto, Kazuaki; Chen, Siyu; Zhang, Beidou

    2017-02-01

    Based on 8 years of (January 2008-December 2015) cloud phase information from the GCM-Oriented Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud Product (GOCCP), aerosol products from CALIPSO and meteorological parameters from the ERA-Interim products, the present study investigates the effects of atmospheric dynamics on the supercooled liquid cloud fraction (SCF) during nighttime under different aerosol loadings at global scale to better understand the conditions of supercooled liquid water gradually transforming to ice phase. Statistical results indicate that aerosols' effect on nucleation cannot fully explain all SCF changes, especially in those regions where aerosols' effect on nucleation is not a first-order influence (e.g., due to low ice nuclei aerosol frequency). By performing the temporal and spatial correlations between SCFs and different meteorological factors, this study presents specifically the relationship between SCF and different meteorological parameters under different aerosol loadings on a global scale. We find that the SCFs almost decrease with increasing of aerosol loading, and the SCF variation is closely related to the meteorological parameters but their temporal relationship is not stable and varies with the different regions, seasons and isotherm levels. Obviously negative temporal correlations between SCFs versus vertical velocity and relative humidity indicate that the higher vertical velocity and relative humidity the smaller SCFs. However, the patterns of temporal correlation for lower-tropospheric static stability, skin temperature and horizontal wind are relatively more complex than those of vertical velocity and humidity. For example, their close correlations are predominantly located in middle and high latitudes and vary with latitude or surface type. Although these statistical correlations have not been used to establish a certain causal relationship, our results may provide a unique point of view

  3. Externally applied electric fields up to 1.6 × 10(5) V/m do not affect the homogeneous nucleation of ice in supercooled water.

    Science.gov (United States)

    Stan, Claudiu A; Tang, Sindy K Y; Bishop, Kyle J M; Whitesides, George M

    2011-02-10

    The freezing of water can initiate at electrically conducting electrodes kept at a high electric potential or at charged electrically insulating surfaces. The microscopic mechanisms of these phenomena are unknown, but they must involve interactions between water molecules and electric fields. This paper investigates the effect of uniform electric fields on the homogeneous nucleation of ice in supercooled water. Electric fields were applied across drops of water immersed in a perfluorinated liquid using a parallel-plate capacitor; the drops traveled in a microchannel and were supercooled until they froze due to the homogeneous nucleation of ice. The distribution of freezing temperatures of drops depended on the rate of nucleation of ice, and the sensitivity of measurements allowed detection of changes by a factor of 1.5 in the rate of nucleation. Sinusoidal alternation of the electric field at frequencies from 3 to 100 kHz prevented free ions present in water from screening the electric field in the bulk of drops. Uniform electric fields in water with amplitudes up to (1.6 ± 0.4) × 10(5) V/m neither enhanced nor suppressed the homogeneous nucleation of ice. Estimations based on thermodynamic models suggest that fields in the range of 10(7)-10(8) V/m might cause an observable increase in the rate of nucleation.

  4. Boson peak, Ioffe-Regel Crossover, and Liquid-Liquid phase transition in Supercooled Water

    Science.gov (United States)

    Kumar, Pradeep

    We have investigated the onset of Boson peak in a model of liquid water which exhibits a clear first-order phase transition between a low-density liquid phase and a high-density liquid phase of water at low temperature and high pressure. We find that the at low pressures, the onset of Boson peak coincides with the Widom-line of the system. At high pressures, the onset occurs at the transition temperature between the two liquids. Furthermore, we show that at both low and high pressure, the frequency of the Boson peak coincides with the Ioffe-Regel crossover of the transverse phonons, suggesting that the breakdown of Debye behavior is a general feature of Ioffe-Regel limit crossover in supercooled water. The frequency of the Boson peak is weakly pressure dependent and decreases with increasing pressure. Our work bridges gap between the experimental results on the Boson peak nanoconfined water and the behavior that one would expect from a bulk system.

  5. Two-structure thermodynamics for the TIP4P/2005 model of water covering supercooled and deeply stretched regions

    Science.gov (United States)

    Biddle, John W.; Singh, Rakesh S.; Sparano, Evan M.; Ricci, Francesco; González, Miguel A.; Valeriani, Chantal; Abascal, José L. F.; Debenedetti, Pablo G.; Anisimov, Mikhail A.; Caupin, Frédéric

    2017-01-01

    One of the most promising frameworks for understanding the anomalies of cold and supercooled water postulates the existence of two competing, interconvertible local structures. If the non-ideality in the Gibbs energy of mixing overcomes the ideal entropy of mixing of these two structures, a liquid-liquid phase transition, terminated at a liquid-liquid critical point, is predicted. Various versions of the "two-structure equation of state" (TSEOS) based on this concept have shown remarkable agreement with both experimental data for metastable, deeply supercooled water and simulations of molecular water models. However, existing TSEOSs were not designed to describe the negative pressure region and do not account for the stability limit of the liquid state with respect to the vapor. While experimental data on supercooled water at negative pressures may shed additional light on the source of the anomalies of water, such data are very limited. To fill this gap, we have analyzed simulation results for TIP4P/2005, one of the most accurate classical water models available. We have used recently published simulation data, and performed additional simulations, over a broad range of positive and negative pressures, from ambient temperature to deeply supercooled conditions. We show that, by explicitly incorporating the liquid-vapor spinodal into a TSEOS, we are able to match the simulation data for TIP4P/2005 with remarkable accuracy. In particular, this equation of state quantitatively reproduces the lines of extrema in density, isothermal compressibility, and isobaric heat capacity. Contrary to an explanation of the thermodynamic anomalies of water based on a "retracing spinodal," the liquid-vapor spinodal in the present TSEOS continues monotonically to lower pressures upon cooling, influencing but not giving rise to density extrema and other thermodynamic anomalies.

  6. Free energy of formation of small ice nuclei near the Widom line in simulations of supercooled water.

    Science.gov (United States)

    Buhariwalla, Connor R C; Bowles, Richard K; Saika-Voivod, Ivan; Sciortino, Francesco; Poole, Peter H

    2015-05-01

    The ST2 interaction potential has been used in a large number of simulation studies to explore the possibility of a liquid-liquid phase transition (LLPT) in supercooled water. Using umbrella sampling Monte Carlo simulations of ST2 water, we evaluate the free energy of formation of small ice nuclei in the supercooled liquid in the vicinity of the Widom line, the region above the critical temperature of the LLPT where a number of thermodynamic anomalies occur. Our results show that in this region there is a substantial free-energy cost for the formation of small ice nuclei, demonstrating that the thermodynamic anomalies associated with the Widom line in ST2 water occur in a well-defined metastable liquid phase. On passing through the Widom line, we identify changes in the free energy to form small ice nuclei that illustrate how the thermodynamic anomalies associated with the LLPT may influence the ice nucleation process.

  7. Experimental studies on seasonal heat storage based on stable supercooling of a sodium acetate water mixture

    DEFF Research Database (Denmark)

    Furbo, Simon; Dragsted, Janne; Fan, Jianhua

    2011-01-01

    to transfer heat to and from the module have been tested. Further, a solidification start method, based on a strong cooling of a small part of the salt water mixture in the module by boiling CO2 in a small brass tank in good thermal contact to the outer side of the module wall, has been tested. Tests......Laboratory tests of a 230 l seasonal heat storage module with a sodium acetate water mixture have been carried out. The aim of the tests is to elucidate how best to design a seasonal heat storage based on the salt water mixture, which supercools in a stable way. The module can be a part...... of a seasonal heat storage, that will be suitable for solar heating systems which can fully cover the yearly heat demand of Danish low energy buildings. The tested module has approximately the dimensions 2020 mm x 1285 mm x 80 mm. The module material is steel and the wall thickness is 2 mm. Different methods...

  8. Size dependence of volume and surface nucleation rates for homogeneous freezing of supercooled water droplets

    Directory of Open Access Journals (Sweden)

    T. Kuhn

    2011-03-01

    Full Text Available The relative roles of volume and surface nucleation were investigated for the homogeneous freezing of pure water droplets. Experiments were carried out in a cryogenic laminar aerosol flow tube using supercooled water aerosols with maximum volume densities at radii between 1 and 3 μm. Temperature- and size-dependent values of volume- and surface-based homogeneous nucleation rates between 234.8 and 236.2 K were derived using a microphysical model and aerosol phase compositions and size distributions determined from infrared extinction measurements in the flow tube. The results show that the contribution from nucleation at the droplet surface increases with decreasing droplet radius and dominates over nucleation in the bulk droplet volume for droplets with radii smaller than approximately 5 μm. This is interpreted in terms of a lowered free energy of ice germ formation in the surface-based process. The implications of surface nucleation for the parameterization of homogeneous ice nucleation in numerical models are considered.

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

    Science.gov (United States)

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

    2014-03-01

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

  10. Detection of supercooled liquid water-topped mixed-phase clouds >from shortwave-infrared satellite observations

    Science.gov (United States)

    NOH, Y. J.; Miller, S. D.; Heidinger, A. K.

    2015-12-01

    Many studies have demonstrated the utility of multispectral information from satellite passive radiometers for detecting and retrieving the properties of cloud globally, which conventionally utilizes shortwave- and thermal-infrared bands. However, the satellite-derived cloud information comes mainly from cloud top or represents a vertically integrated property. This can produce a large bias in determining cloud phase characteristics, in particular for mixed-phase clouds which are often observed to have supercooled liquid water at cloud top but a predominantly ice phase residing below. The current satellite retrieval algorithms may report these clouds simply as supercooled liquid without any further information regarding the presence of a sub-cloud-top ice phase. More accurate characterization of these clouds is very important for climate models and aviation applications. In this study, we present a physical basis and preliminary results for the algorithm development of supercooled liquid-topped mixed-phase cloud detection using satellite radiometer observations. The detection algorithm is based on differential absorption properties between liquid and ice particles in the shortwave-infrared bands. Solar reflectance data in narrow bands at 1.6 μm and 2.25 μm are used to optically probe below clouds for distinction between supercooled liquid-topped clouds with and without an underlying mixed phase component. Varying solar/sensor geometry and cloud optical properties are also considered. The spectral band combination utilized for the algorithm is currently available on Suomi NPP Visible/Infrared Imaging Radiometer Suite (VIIRS), Himawari-8 Advanced Himawari Imager (AHI), and the future GOES-R Advance Baseline Imager (ABI). When tested on simulated cloud fields from WRF model and synthetic ABI data, favorable results were shown with reasonable threat scores (0.6-0.8) and false alarm rates (0.1-0.2). An ARM/NSA case study applied to VIIRS data also indicated promising

  11. Static and dynamic length scales in supercooled liquids: insights from molecular dynamics simulations of water and tri-propylene oxide.

    Science.gov (United States)

    Klameth, F; Henritzi, P; Vogel, M

    2014-04-14

    We perform molecular dynamics simulations to study static and dynamic length scales in molecular supercooled liquids, in particular, water. For a determination of these scales, we use equilibrium configurations and pin appropriate subsets of molecules so as to obtain random matrices, cylindrical pores, and slit confinements. Static length scales ξ(s) are determined by analyzing overlap correlation functions for various fractions of pinned molecules or distances to the confining walls. For water in all confinements and for propylene oxide trimers in random geometry, a linear increase of ξ(s) with inverse temperature is found. Dynamic length scales ξ(d) are determined by analogous analysis of fraction-dependent or position-resolved correlation times of structural relaxation. While ξ(d) continuously grows upon cooling in the cylindrical and slit confinements, we find no evidence for a temperature dependence in random matrices, implying that molecular dynamics in parsed volumes is qualitatively different from that in bulk liquids. Finally, we study possible connections between the growth of the static and dynamic length scales and the slowdown of the structural relaxation of the supercooled bulk liquids. For water, we observe a linear relation between ln τ(α) and ξ(s)²/T in the whole accessible range down to the critical temperature of mode-coupling theory, T(c). In the weakly supercooled regime, the same relation holds also for ξ(d), as obtained from cylindrical and slit confinements, but deviations from this behavior are observed near T(c). The results are discussed in connection with random first-order theory and experimental studies of liquid dynamics in nanoscopic confinements and binary mixtures.

  12. NMR evidence of a sharp change in a measure of local order in deeply supercooled confined water

    OpenAIRE

    Mallamace, F.; Corsaro, C.; Broccio, M.; Branca, C.; González-Segredo, N.; Spooren, J.; Chen, S. -H.; Stanley, H. E.

    2008-01-01

    Using NMR, we measure the proton chemical shift δ, of supercooled nanoconfined water in the temperature range 195 K < T < 350 K. Because δ is directly connected to the magnetic shielding tensor, we discuss the data in terms of the local hydrogen bond geometry and order. We argue that the derivative −(∂ ln δ/∂T)P should behave roughly as the constant pressure specific heat CP(T), and we confirm this argument by detailed comparisons with literature values of CP(T) in the range 290–370 K. We fin...

  13. Observations on the Freezing of Supercooled Pollen Washing Water by a New Electrodynamic Balance

    Science.gov (United States)

    Tong, Haijie; Pope, Francis D.; Kalberer, Markus

    2014-05-01

    Primary biological particles can act as efficient ice nuclei (IN) by initiating freezing events at temperatures warmer than the homogenous freezing temperature [1, 2]. For example, pollen grain particles can trigger freezing events at temperatures as warm as -5 °C in the contact freezing mode [3]. More recently pollen residues, which are released by washing pollen grains in water, were also observed to act as efficient IN in the immersion mode [4, 5]. In this study we developed a new cold electrodynamic balance (CEDB) system and investigated the freezing properties of single particles of supercooled pollen washing water (SPWW). The EDB technique allows for a contact free measurement of freezing events. The phase of the particle (liquid or frozen solid) can be distinguished via measuring the Mie scattering signal from the particle. Furthermore the size of liquid (spherical) particles can be determined. The freezing events are characterized through the loss of the regular Mie scattering signal from the levitated droplet as it changes state from liquid to a frozen solid. The statistical freezing probabilities of SPWW were obtained in the temperature range: -15 to -40 °C. Each temperature measurement point consists of the analysis of 30-100 droplets. Preliminary conclusions are that SPWW is IN active in the immersion mode. Further discussion will focus on the temperature range of the IN activity, the important variables (other than temperature) for IN activity, other likely modes of IN activity, and the implications of these results in terms of the atmospheric relevance of SPWW. This study was supported by the NERC. We acknowledge Professor Jonathan Reid and James Davis from the University of Bristol for providing information of the design of the warm EDB system. References: [1] Möhler, O., et al. (2007) Biogeosciences, 4, 1059-1071. [2] Prenni, A. J., et al. (2009) Nat. Geosci., 2, 401-404. [3] Diehl, K., et al. (2002) Atmos. Res., 61, 125-133. [4] Pummer, B. G

  14. Nature of the anomalies in the supercooled liquid state of the mW model of water

    CERN Document Server

    Holten, Vincent; Molinero, Valeria; Anisimov, Mikhail A

    2013-01-01

    The thermodynamic properties of the supercooled liquid state of the mW model of water show anomalous behavior. Like in real water, the heat capacity and compressibility sharply increase upon supercooling. One of the possible explanations of these anomalies, the existence of a second (liquid-liquid) critical point, is not supported by simulations for this particular model. In this work, we reproduce the anomalies of the mW model with two thermodynamic scenarios: one based on a non-ideal "mixture" with two different types of local order of the water molecules, and one based on weak crystallization theory. We show that both descriptions accurately reproduce the model's basic thermodynamic properties. However, the coupling constant required for fitting the power laws implied by weak crystallization theory is found not to be physically meaningful. For the two-state approach, the direct computation of the low-density fraction of molecules in the mW model is in agreement with the prediction of the phenomenological e...

  15. A systematic experimental study on the evaporation rate of supercooled water droplets at subzero temperatures and varying relative humidity

    Science.gov (United States)

    Ruberto, S.; Reutzsch, J.; Roth, N.; Weigand, B.

    2017-05-01

    Supercooled water droplets (SWD) are present in clouds at high altitude and subjected to very low temperatures and high relative humidity. These droplets exist in a metastable state. The understanding of the evaporation of SWD at these extreme conditions is of high interest to understand rain, snow, and hail generating mechanisms in clouds. This paper focuses on the experimental results of the measurements of the evaporation rates β of supercooled water droplets. For this purpose, single SWDs are trapped by means of optical levitation. During the evaporation process, the elastically scattered light in the forward regime is recorded and evaluated. Experiments have been performed for different relative humidities φ at three constant ambient temperatures, namely, {T_∞}=268.15; 263.15; 253.15 {{K}} ({t_∞} = -5; -10; -20°C). The experimental data agrees well with direct numerical simulations (DNS) carried out with the in-house code Free Surface 3D (FS3D) and shows that the use of a simplified model is permissible for these ambient conditions.

  16. NMR evidence of a sharp change in a measure of local order in deeply supercooled confined water.

    Science.gov (United States)

    Mallamace, F; Corsaro, C; Broccio, M; Branca, C; González-Segredo, N; Spooren, J; Chen, S-H; Stanley, H E

    2008-09-02

    Using NMR, we measure the proton chemical shift delta, of supercooled nanoconfined water in the temperature range 195 K < T < 350 K. Because delta is directly connected to the magnetic shielding tensor, we discuss the data in terms of the local hydrogen bond geometry and order. We argue that the derivative -( partial differential ln delta/ partial differentialT)(P) should behave roughly as the constant pressure specific heat C(P)(T), and we confirm this argument by detailed comparisons with literature values of C(P)(T) in the range 290-370 K. We find that -( partial differential ln delta/ partial differentialT)(P) displays a pronounced maximum upon crossing the locus of maximum correlation length at approximately 240 K, consistent with the liquid-liquid critical point hypothesis for water, which predicts that C(P)(T) displays a maximum on crossing the Widom line.

  17. Vapor Pressure Plus: An Experiment for Studying Phase Equilibria in Water, with Observation of Supercooling, Spontaneous Freezing, and the Triple Point

    Science.gov (United States)

    Tellinghuisen, Joel

    2010-01-01

    Liquid-vapor, solid-vapor, and solid-liquid-vapor equilibria are studied for the pure substance water, using modern equipment that includes specially fabricated glass cells. Samples are evaporatively frozen initially, during which they typically supercool to -5 to -10 [degrees]C before spontaneously freezing. Vacuum pumping lowers the temperature…

  18. Anharmonic activations in proteins and peptide model systems and their connection with supercooled water thermodynamics

    Science.gov (United States)

    Schirò, G.; Cupane, A.

    2016-05-01

    Proteins, the nano-machines of living systems, are highly dynamic molecules. The time-scale of functionally relevant motions spans over a very broad range, from femtoseconds to several seconds. In particular, the pico- to nanoseconds region is characterized by side-chain and backbone anharmonic fluctuations that are responsible for many biological tasks like ligand binding, substrate recognition and enzymatic activity. Neutron scattering on hydrated protein powders reveals two main activations of anharmonic dynamics, characterized by different onset temperature and amplitude. Here we review our work on synthetic polypeptides, native proteins, and single amino acids to identify the physical origin of the two onsets -one involving water-independent local dynamics of methyl groups and, to a minor extent, of aromatic side-chains, and the other one, known as "protein dynamical transition", concerning large scale functional protein fluctuations, most likely induced by a crossover in the structure and dynamics of hydration water connected with the second critical point hypothesis.

  19. Towards 3D prediction of supercooled liquid water for aircraft icing: Modifications of the microphysics in COSMO-EU

    Directory of Open Access Journals (Sweden)

    Felix Köhler

    2014-09-01

    Full Text Available Supercooled liquid water (SLW in the atmosphere is responsible for aircraft icing which can cause severe accidents. To date, the microphysics scheme in the model of the Deutscher Wetterdienst (DWD for the European scale (COSMO-EU; due to be replaced by ICON-EU in 2015 has been optimised to forecast precipitation on the ground but not the water phase in the atmosphere. As a consequence, prediction of SLW is rather poor, as was shown in a series of case studies by the Aeronautical Meteorology department at DWD. ADWICE – the tool used by the DWD to predict aircraft icing – therefore does not rely on COSMO model SLW output, but predicts SLW by itself using a simple parcel method. In an effort to improve ADWICE it has been found that this algorithm has its limits and that it should be replaced by SLW prediction from a 3D weather prediction model. To this end it is necessary to improve the SLW prediction in the COSMO model. In this paper we analyse the microphysics scheme of COSMO-EU with respect to SLW production and depletion and present modifications that greatly improve SLW prediction. As reference for two case studies we use radar-lidar-radiometer products from the Meteorological Observatory Lindenberg to verify the change in SLW prediction.

  20. Protocol for Measuring the Thermal Properties of a Supercooled Synthetic Sand-water-gas-methane Hydrate Sample.

    Science.gov (United States)

    Muraoka, Michihiro; Susuki, Naoko; Yamaguchi, Hiroko; Tsuji, Tomoya; Yamamoto, Yoshitaka

    2016-03-21

    Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates. The thermal properties' measurements of samples comprising sand, water, methane, and MH are difficult because the melting heat of MH may affect the measurements. To solve this problem, we performed thermal properties' measurements at supercooled conditions during MH formation. The measurement protocol, calculation method of the saturation change, and tips for thermal constants' analysis of the sample using transient plane source techniques are described here. The effect of the formation heat of MH on measurement is very small because the gas hydrate formation rate is very slow. This measurement method can be applied to the thermal properties of the gas hydrate-water-guest gas system, which contains hydrogen, CO2, and ozone hydrates, because the characteristic low formation rate of gas hydrate is not unique to MH. The key point of this method is the low rate of phase transition of the target material. Hence, this method may be applied to other materials having low phase-transition rates.

  1. Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water

    Science.gov (United States)

    Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-ichiro; Sazaki, Gen

    2017-01-01

    The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as ‘antifreeze’ in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing. PMID:28262787

  2. Supercooled interfacial water in fine grained soils probed by dielectric spectroscopy

    Science.gov (United States)

    Lorek, A.; Wagner, N.

    2013-04-01

    Water as thermodynamic state parameter affects nearly all physical, chemical and biological processes on the earth. Recent Mars observations as well as laboratory investigations suggest that water is also a key factor of current physical and chemical processes on the martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid like state of water on martian analog soils in the temperature range below 0 °C. In this context, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine grained soils in the frequency range from 10 Hz to 1.1 MHz at martian like temperatures down to -70 °C. Two martian analogue soils have been investigated: a Ca-Bentonite (specific surface of 237 m2 g-1, up to 9.4% w/w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g-1, up to 7.4% w/w). Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak high frequency processes (bound or hydrated water as well as ice) and a strong low frequency process due to counter ion relaxation and the Maxwell-Wagner effect. To characterize the dielectric relaxation behavior, a generalized fractional dielectric relaxation model is applied assuming three active relaxation processes with relaxation time of the ith process according to an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid like water content by means of the Birchak or CRIM equation. There are evidence that Bentonite down to -70 °C has a liquid like water content of 1.17 monolayers and JSC Mars 1 a liquid like water content of 1.96 mono layers.

  3. Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy

    Science.gov (United States)

    Lorek, A.; Wagner, N.

    2013-12-01

    Water substantially affects nearly all physical, chemical and biological processes on the Earth. Recent Mars observations as well as laboratory investigations suggest that water is a key factor of current physical and chemical processes on the Martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid-like state of water on Martian analogue soils for temperatures below 0 °C. To this end, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine-grained soils in the frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to -70 °C. Two Martian analogue soils have been investigated: a Ca-bentonite (specific surface of 237 m2 g-1, up to 9.4% w / w gravimetric water content) and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g-1, up to 7.4% w / w). Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak high-frequency processes (bound or hydrated water as well as ice) and a strong low-frequency process due to counter-ion relaxation and the Maxwell-Wagner effect. To characterize the dielectric relaxation behaviour, a generalized fractional dielectric relaxation model was applied assuming three active relaxation processes with relaxation time of the ith process modelled with an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid-like water content by means of the Birchak or CRIM equation. There are evidence that bentonite down to -70 °C has a liquid-like water content of 1.17 monolayers and JSC Mars 1 a liquid-like water content of 1.96 monolayers.

  4. The violation of the Stokes–Einstein relation in supercooled water

    OpenAIRE

    Chen, Sow-Hsin; Mallamace, Francesco; Mou, Chung-Yuan; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li

    2006-01-01

    By confining water in nanopores, so narrow that the liquid cannot freeze, it is possible to explore its properties well below its homogeneous nucleation temperature TH≈ 235 K. In particular, the dynamical parameters of water can be measured down to 180 K, approaching the suggested glass transition temperature Tg≈ 165 K. Here we present experimental evidence, obtained from Nuclear Magnetic Resonance and Quasi-Elastic Neutron Scattering spectroscopies, of a well defined decoupling of transport ...

  5. Supercooled interfacial water in fine grained soils probed by dielectric spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Lorek

    2013-04-01

    Full Text Available Water as thermodynamic state parameter affects nearly all physical, chemical and biological processes on the earth. Recent Mars observations as well as laboratory investigations suggest that water is also a key factor of current physical and chemical processes on the martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid like state of water on martian analog soils in the temperature range below 0 °C. In this context, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine grained soils in the frequency range from 10 Hz to 1.1 MHz at martian like temperatures down to −70 °C. Two martian analogue soils have been investigated: a Ca-Bentonite (specific surface of 237 m2 g−1, up to 9.4% w/w gravimetric water content and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g−1, up to 7.4% w/w. Three soil-specific relaxation processes are observed in the investigated frequency-temperature range: two weak high frequency processes (bound or hydrated water as well as ice and a strong low frequency process due to counter ion relaxation and the Maxwell–Wagner effect. To characterize the dielectric relaxation behavior, a generalized fractional dielectric relaxation model is applied assuming three active relaxation processes with relaxation time of the ith process according to an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid like water content by means of the Birchak or CRIM equation. There are evidence that Bentonite down to −70 °C has a liquid like water content of 1.17 monolayers and JSC Mars 1 a liquid like water content of 1.96 mono layers.

  6. Supercooled interfacial water in fine-grained soils probed by dielectric spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Lorek

    2013-12-01

    Full Text Available Water substantially affects nearly all physical, chemical and biological processes on the Earth. Recent Mars observations as well as laboratory investigations suggest that water is a key factor of current physical and chemical processes on the Martian surface, e.g. rheological phenomena. Therefore it is of particular interest to get information about the liquid-like state of water on Martian analogue soils for temperatures below 0 °C. To this end, a parallel plate capacitor has been developed to obtain isothermal dielectric spectra of fine-grained soils in the frequency range from 10 Hz to 1.1 MHz at Martian-like temperatures down to −70 °C. Two Martian analogue soils have been investigated: a Ca-bentonite (specific surface of 237 m2 g−1, up to 9.4% w / w gravimetric water content and JSC Mars 1, a volcanic ash (specific surface of 146 m2 g−1, up to 7.4% w / w. Three soil-specific relaxation processes are observed in the investigated frequency–temperature range: two weak high-frequency processes (bound or hydrated water as well as ice and a strong low-frequency process due to counter-ion relaxation and the Maxwell–Wagner effect. To characterize the dielectric relaxation behaviour, a generalized fractional dielectric relaxation model was applied assuming three active relaxation processes with relaxation time of the ith process modelled with an Eyring equation. The real part of effective complex soil permittivity at 350 kHz was used to determine ice and liquid-like water content by means of the Birchak or CRIM equation. There are evidence that bentonite down to −70 °C has a liquid-like water content of 1.17 monolayers and JSC Mars 1 a liquid-like water content of 1.96 monolayers.

  7. The violation of the Stokes-Einstein relation in supercooled water.

    Science.gov (United States)

    Chen, Sow-Hsin; Mallamace, Francesco; Mou, Chung-Yuan; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li

    2006-08-29

    By confining water in nanopores, so narrow that the liquid cannot freeze, it is possible to explore its properties well below its homogeneous nucleation temperature T(H) approximately equals 235 K. In particular, the dynamical parameters of water can be measured down to 180 K, approaching the suggested glass transition temperature T(g) approximately equals 165 K. Here we present experimental evidence, obtained from Nuclear Magnetic Resonance and Quasi-Elastic Neutron Scattering spectroscopies, of a well defined decoupling of transport properties (the self-diffusion coefficient and the average translational relaxation time), which implies the breakdown of the Stokes-Einstein relation. We further show that such a non-monotonic decoupling reflects the characteristics of the recently observed dynamic crossover, at approximately 225 K, between the two dynamical behaviors known as fragile and strong, which is a consequence of a change in the hydrogen bond structure of liquid water.

  8. From the Cover: The violation of the Stokes-Einstein relation in supercooled water

    Science.gov (United States)

    Chen, Sow-Hsin; Mallamace, Francesco; Mou, Chung-Yuan; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li

    2006-08-01

    By confining water in nanopores, so narrow that the liquid cannot freeze, it is possible to explore its properties well below its homogeneous nucleation temperature TH 235 K. In particular, the dynamical parameters of water can be measured down to 180 K, approaching the suggested glass transition temperature Tg 165 K. Here we present experimental evidence, obtained from Nuclear Magnetic Resonance and Quasi-Elastic Neutron Scattering spectroscopies, of a well defined decoupling of transport properties (the self-diffusion coefficient and the average translational relaxation time), which implies the breakdown of the Stokes-Einstein relation. We further show that such a non-monotonic decoupling reflects the characteristics of the recently observed dynamic crossover, at 225 K, between the two dynamical behaviors known as fragile and strong, which is a consequence of a change in the hydrogen bond structure of liquid water. decoupling of transport properties | dynamic crossover | MCM-41

  9. The violation of the Stokes–Einstein relation in supercooled water

    Science.gov (United States)

    Chen, Sow-Hsin; Mallamace, Francesco; Mou, Chung-Yuan; Broccio, Matteo; Corsaro, Carmelo; Faraone, Antonio; Liu, Li

    2006-01-01

    By confining water in nanopores, so narrow that the liquid cannot freeze, it is possible to explore its properties well below its homogeneous nucleation temperature TH≈ 235 K. In particular, the dynamical parameters of water can be measured down to 180 K, approaching the suggested glass transition temperature Tg≈ 165 K. Here we present experimental evidence, obtained from Nuclear Magnetic Resonance and Quasi-Elastic Neutron Scattering spectroscopies, of a well defined decoupling of transport properties (the self-diffusion coefficient and the average translational relaxation time), which implies the breakdown of the Stokes–Einstein relation. We further show that such a non-monotonic decoupling reflects the characteristics of the recently observed dynamic crossover, at ≈225 K, between the two dynamical behaviors known as fragile and strong, which is a consequence of a change in the hydrogen bond structure of liquid water. PMID:16920792

  10. Volume of supercooled water under pressure and the liquid-liquid critical point.

    Science.gov (United States)

    Mishima, Osamu

    2010-10-14

    The volume of water (H(2)O) was obtained at about 200-275 K and 40-400 MPa by using emulsified water. The plot of volume against temperature showed slightly concave-downward curvature at pressures higher than ≈200 MPa. This is compatible with the liquid-liquid critical-point hypothesis, but hardly with the singularity-free scenario. When the critical point is assumed to exist at ≈50 MPa and ≈223 K, the experimental volume and the derived compressibility are qualitatively described by the modified Fuentevilla-Anisimov scaling equation.

  11. An Investigation of Freezing of Supercooled Water on Anti-Freeze Protein Modified Surfaces

    Institute of Scientific and Technical Information of China (English)

    Thibaut V J Charpentier; Anne Neville; Paul Millner; Rob Hewson; Ardian Morina

    2013-01-01

    This work investigates how functionalization ofaluminium surfaces with natural type Ⅲ Anti-Freeze Protein (AFP) affects the mechanism of heterogeneous ice nucleation.First the bulk ice nucleation properties of distilled water and aqueous solution of AFP were evaluated by differential scanning calorimetry.Then the modified surface was characterized by Secondary Ions Mass Spectroscopy (SIMS),Fourier Transform InfraRed (FTIR) spectroscopy and contact angle measurement.Freezing experiments were then conducted in which water droplets underwent a slow controlled cooling.This study shows that compared to uncoated aluminium,the anti-freeze proteins functionalized surfaces exhibit a higher and narrower range of freezing temperature.It was found that these proteins that keep living organisms from freezing in cold environment act in the opposite way once immobilized on surfaces by promoting ice nucleation.Some suggestions regarding the mechanism of action of the observed phenomena were proposed based on the Classical Nucleation Theory (CNT).

  12. Supercooling of aqueous dimethylsulfoxide solution at normal and high pressures: Evidence for the coexistence of phase-separated aqueous dimethylsulfoxide solutions of different water structures.

    Science.gov (United States)

    Kanno, H; Kajiwara, K; Miyata, K

    2010-05-21

    Supercooling behavior of aqueous dimethylsulfoxide (DMSO) solution was investigated as a function of DMSO concentration and at high pressures. A linear relationship was observed for T(H) (homogeneous ice nucleation temperature) and T(m) (melting temperature) for the supercooling of aqueous DMSO solution at normal pressure. Analysis of the DTA (differential thermal analysis) traces for homogeneous ice crystallization in the bottom region of the T(H) curve for a DMSO solution of R=20 (R: moles of water/moles of DMSO) at high pressures supported the contention that the second critical point (SCP) of liquid water should exist at P(c2)= approximately 200 MPa and at T(c2)temperature of SCP). The presence of two T(H) peaks for DMSO solutions (R=15, 12, and 10) suggests that phase separation occurs in aqueous DMSO solution (Rtemperatures (different liquid water structures [LDL-like and HDL-like structures (LDL: low-density liquid water, HDL: high-density liquid water)] in the pressure range of 120-230 MPa.

  13. Supercooled Water Droplet Impacting Superhydrophobic Surfaces in the Presence of Cold Air Flow

    Directory of Open Access Journals (Sweden)

    Morteza Mohammadi

    2017-01-01

    Full Text Available In the present work, an investigation of stagnation flow imposed on a supercooled water drop in cold environmental conditions was carried out at various air velocities ranging from 0 (i.e., still air to 10 m/s along with temperature spanning from −10 to −30 °C. The net effect of air flow on the impacting water droplet was investigated by controlling the droplet impact velocity to make it similar with and without air flow. In cold atmospheric conditions with temperatures as low as −30 °C, due to the large increase of both internal and contact line viscosity combined with the presence of ice nucleation mechanisms, supercooled water droplet wetting behavior was systematically affected. Instantaneous pinning for hydrophilic and hydrophobic surfaces was observed when the spread drop reached the maximum spreading diameter (i.e., no recoiling phase. Nevertheless, superhydrophobic surfaces showed a great repellency (e.g., contact time reduction up to 30% where air velocity was increased up to 10 m/s at temperatures above the critical temperature of heterogeneous ice nucleation (i.e., −24 °C. However, the freezing line of the impacting water droplet was extended up to 2-fold at air velocity up to 10 m/s where substrate temperature was maintained below the aforementioned critical temperature (e.g., −30 °C.

  14. Supercooled Liquid Water Content Instrument Analysis and Winter 2014 Data with Comparisons to the NASA Icing Remote Sensing System and Pilot Reports

    Science.gov (United States)

    King, Michael C.

    2016-01-01

    The National Aeronautics and Space Administration (NASA) has developed a system for remotely detecting the hazardous conditions leading to aircraft icing in flight, the NASA Icing Remote Sensing System (NIRSS). Newly developed, weather balloon-borne instruments have been used to obtain in-situ measurements of supercooled liquid water during March 2014 to validate the algorithms used in the NIRSS. A mathematical model and a processing method were developed to analyze the data obtained from the weather balloon soundings. The data from soundings obtained in March 2014 were analyzed and compared to the output from the NIRSS and pilot reports.

  15. Super-cooled liquid water topped sub-arctic clouds and precipitation - investigation based on combination of ground-based in-situ and remote-sensing observations

    Science.gov (United States)

    Hirsikko, Anne; Brus, David; O'Connor, Ewan J.; Filioglou, Maria; Komppula, Mika; Romakkaniemi, Sami

    2017-04-01

    In the high and mid latitudes super-cooled liquid water layers are frequently observed on top of clouds. These layers are difficult to forecast with numerical weather prediction models, even though, they have strong influence on atmospheric radiative properties, cloud microphysical properties, and subsequently, precipitation. This work investigates properties of super-cooled liquid water layer topped sub-arctic clouds and precipitation observed with ground-based in-situ (cloud probes) and remote-sensing (a cloud radar, Doppler and multi-wavelength lidars) instrumentation during two-month long Pallas Cloud Experiment (PaCE 2015) in autumn 2015. Analysis is based on standard Cloudnet scheme supplemented with new retrieval products of the specific clouds and their properties. Combination of two scales of observation provides new information on properties of clouds and precipitation in the sub-arctic Pallas region. Current status of results will be presented during the conference. The authors acknowledge financial support by the Academy of Finland (Centre of Excellence Programme, grant no 272041; and ICINA project, grant no 285068), the ACTRIS2 - European Union's Horizon 2020 research and innovation programme under grant agreement No 654109, the KONE foundation, and the EU FP7 project BACCHUS (grant no 603445).

  16. Numerical and experimental verification of a theoretical model of ripple formation in ice growth under supercooled water film flow

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, K; Farzaneh, M [NSERC/Hydro-Quebec/UQAC Industrial Chair on Atmospheric Icing of Power Network Equipment (CIGELE) and Canada Research Chair on Engineering of Power Network Atmospheric Icing (INGIVRE), Universite du Quebec a Chicoutimi, 555 Boulevard de l' Universite, Chicoutimi, Quebec, G7H 2B1 (Canada); Yamaguchi, S [Snow and Ice Research Center, National Research Institute for Earth Science and Disaster Prevention, Nagaoka, 940-0821 (Japan); Tsuji, H [Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka, 816-8580 (Japan)], E-mail: kazuto.ueno@uqac.ca

    2010-04-15

    Little is known about morphological instability of a solidification front during the crystal growth of a thin film of flowing supercooled liquid with a free surface: for example, the ring-like ripples on the surface of icicles. The length scale of the ripples is nearly 1 cm. Two theoretical models for the ripple formation mechanism have been proposed. However, these models lead to quite different results because of differences in the boundary conditions at the solid-liquid interface and liquid-air surface. The validity of the assumption used in the two models is numerically investigated and some of the theoretical predictions are compared with experiments.

  17. Mixed quantum/classical approach to OH-stretch inelastic incoherent neutron scattering spectroscopy for ambient and supercooled liquid water and ice Ih

    Energy Technology Data Exchange (ETDEWEB)

    Shi, L.; Skinner, J. L. [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2015-07-07

    OH-stretch inelastic incoherent neutron scattering (IINS) has been measured to determine the vibrational density of states (VDOS) in the OH-stretch region for liquid water, supercooled water, and ice Ih, providing complementary information to IR and Raman spectroscopies about hydrogen bonding in these phases. In this work, we extend the combined electronic-structure/molecular-dynamics (ES/MD) method, originally developed by Skinner and co-workers to simulate OH-stretch IR and Raman spectra, to the calculation of IINS spectra with small k values. The agreement between theory and experiment in the limit k → 0 is reasonable, further validating the reliability of the ES/MD method in simulating OH-stretch spectroscopy in condensed phases. The connections and differences between IINS and IR spectra are analyzed to illustrate the advantages of IINS over IR in estimating the OH-stretch VDOS.

  18. What am I? Supercooled droplet or ice?

    CERN Document Server

    Antonini, Carlo; Maitra, Tanmoy; Tiwari, Manish K; Poulikakos, Dimos

    2013-01-01

    In this fluid dynamics video we show the trick played by a supercooled liquid water drop against a superhydrophobic surface. The water drop shows a double personality, impacting onto the surface the first time while still in the liquid state, and then re-impacting as a frozen ice crystal.

  19. 单个水滴蒸发过冷过程的特性分析%Characteristic analysis of single water droplet in evaporative supercooled process

    Institute of Scientific and Technical Information of China (English)

    闫俊海; 张小松; 周斌

    2012-01-01

    To analyze the movement and evaporation characteristics of single water droplet in low temperature and low humidity ratio air, a mathematical model of water droplet heat and mass transfer and movement process was proposed. The evaporation process of droplet in supercooled stage was simulated through theoretical model, results from modeling basically tally with experiment of hanging single water droplet. The temperature, diameter, velocity and trajectory of water droplet during evaporation and motion process and the influence of the initial parameters of droplet and air velocity were investigated. The numerical results show that at a certain spray angle and with same dropping height the smaller droplet diameter can shorten movement distance at horizontal direction and the super-cooled time of water droplet, meanwhile decrease the corresponding velocity of water droplet faster. The lower initial temperature of water droplet or the higher velocity of air can improve the cooling rate of water droplet and the water droplet can be cooled to supercooled state in a very short dropping height. In addition, the higher the initial temperature of water droplet and the air velocity are, the faster the diameter of water droplet reduces. Thus, the precooled water droplets can not only improve the ice-making efficiency but also reduce the evaporative loss of water droplet.%为分析单个水滴在低温、低湿空气中的运动和蒸发特性,建立了描述整个传热传质及运动过程的数学模型,并通过对悬挂水滴的蒸发冷却实验验证了该模型的有效性.通过模拟计算获得了水滴温度、直径、速度和运动轨迹的变化规律,以及水滴初始参数和空气速度对制冰效率的影响.结果表明,水滴在某一喷射角度下,直径越小,同样的下落高度水滴水平飞行的距离越短,而相应的速度衰减则越快,同时水滴蒸发过冷所需的时间越短.另外,水滴初始温度越低和逆流空气速度越高,

  20. The Gibbs-Thomson effect and intergranular melting in ice emulsions: Interpreting the anomalous heat capacity and volume of supercooled water

    Science.gov (United States)

    Johari, G. P.

    1997-12-01

    Calculations for the Gibbs-Thomson effect and the intergranular melting of the ice droplets in (water) emulsions at temperatures below 273.16 K show that water and ice coexist at thermodynamic equilibrium in an apparently frozen emulsion. The fraction of water at this equilibrium increases on heating, which alters further the thermodynamic properties of the emulsion. As some of the ice in the emulsion has already melted, the increase in the enthalpy, H, and heat capacity, Cp, and the decrease in the volume measured on the normal melting at 273.16 K, are less than the values anticipated. The ratio of this increase in H, or Cp, on melting of the emulsion to the corresponding value for pure ice, underestimates the emulsion's water content which, when used for scaling the difference between the Cp of the unfrozen and frozen emulsion at lower temperatures, as in earlier studies, leads to a larger Cp of supercooled water than the actual value. Similar scaling of the corresponding difference between the volume leads to higher volume, or lower density, than the actual value. A formalism for this premelting effect is given for both the adiabatic and differential scanning calorimetry (DSC), and its magnitude is calculated. New experiments show that the rise in the DSC signal, or equivalently in the apparent Cp observed on heating the frozen emulsion, occurs over a temperature range much wider than the Gibbs-Thomson effect and intergranular melting predict, for which reasons are given. It is shown that Cp of the dispersant phase is also affected by the melting of ice droplets. There are four consequences of the premelting effects for all finely dispersed materials, for frozen water emulsions below 273.16 K: (i) water and ice coexist in the emulsion, (ii) its apparent Cp will increase with increase in the heat input used to measure it, (iii) the apparent Cp will increase with decrease in the average size of the droplets, and (iv) the apparent Cp will decrease on annealing the

  1. Supercooled liquids for pedestrians

    Science.gov (United States)

    Cavagna, Andrea

    2009-06-01

    When we lower the temperature of a liquid, at some point we meet a first order phase transition to the crystal. Yet, under certain conditions it is possible to keep the system in its metastable phase and to avoid crystallization. In this way the liquid enters in the supercooled phase. Supercooled liquids have a very rich phenomenology, which is still far from being completely understood. To begin with, there is the problem of how to prevent crystallization and how deeply the liquid can be supercooled before a metastability limit is hit. But by far the most interesting feature of supercooled liquids is the dynamic glass transition: when the temperature is decreased below a certain point, the relaxation time increases so much that a dramatic dynamical arrest intervenes and we are unable to equilibrate the system within reasonable experimental times. The glass transition is a phenomenon whose physical origin has stirred an enormous interest in the last hundred years. Why does it occur? Is it just a conventional reference point, or does it have a more profound physical meaning? Is it a purely dynamical event, or the manifestation of a true thermodynamic transition? What is the correlation length associated to the sharp increase of the relaxation time? Can we define a new kind of amorphous order? A shared theory of supercooled liquids and the glass transition does not yet exist and these questions are still largely open. Here, I will illustrate in the most elementary fashion the main phenomenological traits of supercooled liquids and discuss in a very partial way a few theoretical ideas on the subject.

  2. Predictive Model of Supercooled Water Droplet Pinning/Repulsion Impacting a Superhydrophobic Surface: The Role of the Gas-Liquid Interface Temperature.

    Science.gov (United States)

    Mohammadi, Morteza; Tembely, Moussa; Dolatabadi, Ali

    2017-02-28

    Dynamical analysis of an impacting liquid drop on superhydrophobic surfaces is mostly carried out by evaluating the droplet contact time and maximum spreading diameter. In this study, we present a general transient model of the droplet spreading diameter developed from the previously defined mass-spring model for bouncing drops. The effect of viscosity was also considered in the model by definition of a dash-pot term extracted from experiments on various viscous liquid droplets on a superhydrophobic surface. Furthermore, the resultant shear force of the stagnation air flow was also considered with the help of the classical Homann flow approach. It was clearly shown that the proposed model predicts the maximum spreading diameter and droplet contact time very well. On the other hand, where stagnation air flow is present in contradiction to the theoretical model, the droplet contact time was reduced as a function of both droplet Weber numbers and incoming air velocities. Indeed, the reduction in the droplet contact time (e.g., 35% at a droplet Weber number of up to 140) was justified by the presence of a formed thin air layer underneath the impacting drop on the superhydrophobic surface (i.e., full slip condition). Finally, the droplet wetting model was also further developed to account for low temperature through the incorporation of classical nucleation theory. Homogeneous ice nucleation was integrated into the model through the concept of the reduction of the supercooled water drop surface tension as a function of the gas-liquid interface temperature, which was directly correlated with the Nusselt number of incoming air flow. It was shown that the experimental results was qualitatively predicted by the proposed model under all supercooling conditions (i.e., from -10 to -30 °C).

  3. Supercooled smectic nanoparticles

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Westesen, K; Drechsler, M

    2004-01-01

    The possibility of preparing nanoparticles in the supercooled thermotropic liquid crystalline state from cholesterol esters with saturated acyl chains as well as the incorporation of model drugs into the dispersions was investigated using cholesteryl myristate (CM) as a model cholesterol ester....

  4. Supercooled Liquids and Glasses

    OpenAIRE

    1999-01-01

    In these lectures, which were presented at "Soft and Fragile Matter, Nonequilibrium Dynamics, Metastability and Flow" University of St. Andrews, 8 July - 22 July, 1999, I give an introduction to the physics of supercooled liquids and glasses and discuss some computer simulations done to investigate these systems.

  5. Supercooled smectic nanoparticles

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Westesen, K; Drechsler, M

    2004-01-01

    The possibility of preparing nanoparticles in the supercooled thermotropic liquid crystalline state from cholesterol esters with saturated acyl chains as well as the incorporation of model drugs into the dispersions was investigated using cholesteryl myristate (CM) as a model cholesterol ester....

  6. Modeling of water droplet in super-cooling water evaporative system for ice slurry production%蒸发式过冷水制冰液滴蒸发结晶的模拟

    Institute of Scientific and Technical Information of China (English)

    马善军; 李鹏辉; 孔令健; 李少华; 韩吉田

    2016-01-01

    Ice storage technology is considered as one of the most promising options to achieve the so-called “peak load leveling of power system” and to relieve the contradiction between the supply and demand of peak power currently encountered in China. Among the ice-producing methods being developed around the world, the evaporative supercooling water ice-making one is a new and efficient way for ice slurry production of large scale without ice blockage. Therefore, it is of significant importance to investigate the heat and mass transfer characteristics during the cooling and crystallization process of water droplets in the evaporative supercooling water ice-making chamber to the development of practical ice-making system. In order to analyze the heat and mass transfer characteristics of water droplets in an evaporative super-cooling water system for ice slurry production, we proposed a mathematical model for the cooling and crystallization process of a single water droplet falling in the evaporation chamber with large space, which comprehensively took into account the three different zones of entire liquid phase, solid-liquid interphase and entire solid phase during the cooling and crystallization process of a water droplet. The developed mathematical model was then validated by use of the theoretical and experimental results presented in the available literature and satisfactory agreement was achieved in between the model simulation results and the research ones reported in the literature, indicating the correctness of the mathematical model. The parameter variations of the water droplet with changes in some of the key system operating variables, such as the inlet size and temperature of water droplet, the flow rate and relative humidity of the cold air, were numerically determined by solving the developed mathematical model. Effects of the inlet size and temperature of water droplet, inlet temperature, flow rate and relative humidity of the cold air in the

  7. The local order of supercooled water in solution with LiCl studied by NMR proton chemical shift

    Science.gov (United States)

    Corsaro, C.; Mallamace, D.; Vasi, S.; Cicero, N.; Dugo, G.; Mallamace, F.

    2016-05-01

    We study by means of Nuclear Magnetic Resonance (NMR) spectroscopy the local order of water molecules in solution with lithium chloride at eutectic concentration. In particular, by measuring the proton chemical shift as a function of the temperature in the interval 203{ K}Widom line for water supporting the liquid-liquid transition hypothesis.

  8. Mechanism of supercooled droplet freezing on surfaces

    Science.gov (United States)

    Jung, Stefan; Tiwari, Manish K.; Doan, N. Vuong; Poulikakos, Dimos

    2012-01-01

    Understanding ice formation from supercooled water on surfaces is a problem of fundamental importance and general utility. Superhydrophobic surfaces promise to have remarkable 'icephobicity' and low ice adhesion. Here we show that their icephobicity can be rendered ineffective by simple changes in environmental conditions. Through experiments, nucleation theory and heat transfer physics, we establish that humidity and/or the flow of a surrounding gas can fundamentally switch the ice crystallization mechanism, drastically affecting surface icephobicity. Evaporative cooling of the supercooled liquid can engender ice crystallization by homogeneous nucleation at the droplet-free surface as opposed to the expected heterogeneous nucleation at the substrate. The related interplay between droplet roll-off and rapid crystallization is also studied. Overall, we bring a novel perspective to icing and icephobicity, unveiling the strong influence of environmental conditions in addition to the accepted effects of the surface conditions and hydrophobicity.

  9. Analysis of supercooling degree of water in ball-packed porous structure of different materials and diameters%不同材料和球径的多孔球层内水的过冷度分析

    Institute of Scientific and Technical Information of China (English)

    章学来; 刘田田; 赵群志; 梁笑阳; 徐蔚雯

    2015-01-01

    为研究多孔球层的存在对水过冷的影响,采用不同材料(铝、不锈钢、玻璃)和不同球径(5、8、11 mm)的多孔球层固体基底进行了实验研究。由于水的过冷度并非一定值,因此进行多次实验并采用统计方法进行分析。实验结果表明:多孔球层内蒸馏水的过冷度分布比纯蒸馏水分布更集中,且过冷度值比纯蒸馏水小;同材质不同球径多孔球层内水的平均过冷度整体上随着球径减小而减小;固体基底的热导率越大,多孔球层内水的过冷度分布越集中且平均过冷度也越小;固体基底的热导率较小时,易壁面成核,沿壁面由外向内缓慢结晶,相变时间明显多于均匀成核,而均匀成核一旦形成晶核,晶核就会瞬间长大,形成的冰疏松,因此工程应用中应尽量避免壁面成核。%In order to study the effects of bead-packed porous structure, balls of different materials such as aluminum, stainless steel and glass with different diameters of 5, 8 and 11 mm are added into distilled water forming porous media. Since the supercooling degree of water is not a certain value, the experiments are repeated many times at the same cooling condition and analyzed with statistical methods. The results show that the distribution of the supercooling degree of distilled water in porous media is more concentrated than that of pure distilled water and the supercooling degree of water in porous media is smaller. The average supercooling degree of distilled water decreases with decreasing diameter of the same material balls on the whole. The larger the thermal conductivity of solid substrate is, the more concentrated the distribution of supercooling degree of distilled water in porous media and the smaller the average supercooling degree. In addition, the heterogeneous nucleation is more likely to occur when the thermal conductivity of the solid substrate is small. An annulus solid ice

  10. Supercooled smectic nanoparticles

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Koch, Michel H J; Fahr, Alfred

    2009-01-01

    , laser diffraction combined with polarizing intensity differential scattering, DSC and SAXS. The morphology of selected formulations was studied by freeze-fracture electron microscopy. All smectic nanoparticles with a mixed cholesterol ester matrix were stable against recrystallization when stored...... in the bulk was studied by polarizing light microscopy, differential scanning calorimetry (DSC) and small angle X-ray scattering (SAXS). Colloidal dispersions with pure and mixed cholesterol ester matrices were prepared by high-pressure melt homogenization and characterized by photon correlation spectroscopy...... administration of lipophilic drugs, the cytotoxicity of selected formulations was compared with that of a clinically used colloidal fat emulsion (Lipofundin MCT) in the murine fibroblast cell line L929 using the sulforhodamine B assay. The supercooled smectic nanoparticle formulations display a good overall cell...

  11. Evaporation of water and uptake of HCl and HBr through hexanol films at the surface of supercooled sulfuric acid.

    Science.gov (United States)

    Glass, Samuel V; Park, Seong-Chan; Nathanson, Gilbert M

    2006-06-22

    Vacuum evaporation and molecular beam scattering experiments have been used to monitor the loss of water and dissolution of HCl and HBr in deuterated sulfuric acid at 213 K containing 0 to 100 mM hexanol. The addition of 1-hexanol to the acid creates a surface film of hexyl species. This film becomes more compact with decreasing acidity, ranging from approximately 62% to approximately 68% of maximum packing on 68 to 56 wt % D(2)SO(4), respectively. D(2)O evaporation from 68 wt % acid remains unaltered by the hexyl film, where it is most porous, but is impeded by approximately 20% from 56 and 60 wt % acid. H --> D exchange experiments further indicate that the hexyl film on 68 wt % acid enhances conversion of HCl and HBr into DCl and DBr, which is interpreted as an increase in HCl and HBr entry into the bulk acid. For this permeable hexyl film, the hydroxyl groups of surface hexanol molecules may assist uptake by providing extra sites for HCl and HBr hydrogen bonding and dissociation. In contrast, HCl --> DCl exchange in 60 wt % D(2)SO(4) at first rises with hexyl surface coverage but then drops back to the bare acid value as the hexyl species pack more tightly. HCl entry is actually diminished by the hexyl film on 56 wt % acid, where the film is most compact. These experiments reveal a transition from a porous hexanol film on 68 wt % sulfuric acid that enhances HCl and HBr uptake to one on 56 wt % acid that slightly impedes HCl and D(2)O transport.

  12. Experimental evidence for two distinct deeply supercooled liquid states of water – Response to “Comment on ‘Water's second glass transition”’, by G.P. Johari, Thermochim. Acta (2015)

    Energy Technology Data Exchange (ETDEWEB)

    Stern, J.; Seidl, M. [Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck (Austria); Gainaru, C. [Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund (Germany); Fuentes-Landete, V.; Amann-Winkel, K.; Handle, P.H. [Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck (Austria); Köster, K.W.; Nelson, H. [Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund (Germany); Böhmer, R., E-mail: roland.bohmer@tu-dortmund.de [Fakultät Physik, Technische Universität Dortmund, 44221 Dortmund (Germany); Loerting, T., E-mail: thomas.loerting@uibk.ac.at [Institute of Physical Chemistry, University of Innsbruck, 6020 Innsbruck (Austria)

    2015-10-10

    Highlights: • Two samples of amorphous ices quench-recovered from 140 K to 0.07 GPa are compared. • Calorimetry, X-ray diffraction, dielectric spectroscopy and volumetry are employed. • The two samples are distinct and cannot both be termed “pressure-densified glassy water”. • One route of preparation leads to high- (HDA), and the other to low-density amorphous ice (LDA). • Two distinct glass transitions are observed and interpreted to indicate two liquid H{sub 2}O phases. - Abstract: Recently, our earlier data which led us to conclude that deeply supercooled water displays a second glass transition (Amann-Winkel et al., 2013) was reinterpreted (Johari, 2015). In particular, the increase in heat capacity observed for high-density amorphous ice (HDA) samples at 116 K was reinterpreted to indicate sub-T{sub g} features of low-density amorphous ice's (LDA's) glass transition. We reply to the criticism in detail and report an experiment triggered by the comment on our work. This experiment unequivocally confirms our original interpretation of the observations and reinforces the case for water's second glass transition, its polyamorphism, and the observation of two distinct ultraviscous states of water differing by about 25% in density.

  13. Laboratory test of a prototype heat storage module based on stable supercooling of sodium acetate trihydrate

    DEFF Research Database (Denmark)

    Dannemand, Mark; Kong, Weiqiang; Fan, Jianhua;

    2015-01-01

    Laboratory test of a long term heat storage module utilizing the principle of stable supercooling of 199.5 kg of sodium acetate water mixture has been carried out. Avoiding phase separation of the incongruently melting salt hydrate by using the extra water principle increased the heat storage...... the supercooled sodium acetate water mixture was 194 kJ/kg of sodium acetate water mixture in the first test cycles dropping to 179 kJ/kg in the later test cycles. Instability of the supercooling occurred when the charging periods were short and in the last test cycles where the tube connecting the module...

  14. Supercooling across first-order phase transitions in vortex matter

    Indian Academy of Sciences (India)

    P Chaddah; S B Roy

    2000-06-01

    Hysteresis in cycling through first-order phase transitions in vortex matter, akin to the well-studied phenomenon of supercooling of water, has been discussed in literature. Hysteresis can be seen while varying either temperature or magnetic field (and thus the density of vortices). Our recent work on phase transitions with two control variables shows that the observable region of metastability of the supercooled phase would depend on the path followed in - space, and will be larger when is lowered at constant compared to the case when is lowered at constant . We discuss the effect of isothermal field variations on metastable supercooled states produced by field-cooling. This path dependence is not a priori applicable to metastability caused by reduced diffusivity or hindered kinetics.

  15. The transient behavior of Peltier junctions pulsed with supercooling

    Science.gov (United States)

    Mao, J. N.; Chen, H. X.; Jia, H.; Qian, X. L.

    2012-07-01

    There exists the transient thermoelectric supercooling effect that can be enhanced by keeping on increasing the Peltier cooling effect to compensate for the Joule heating effect and Fourier heat conduction effect arriving at the cold junction, in which a transient cold spike can be produced by superimposing an additional shaped current pulse of a large magnitude on the original steady-state optimum value. Most previous work on the transient supercooling mainly focused on the minimum supercooling temperature achievable and separately analyzed the beneficial or detrimental effects on the transient supercooling performance, which was not clarified quantitatively to what extent the interactional effects were on the enhancement of the transient supercooling performance. In this work, we systematically investigate a numerical solution involving time-dependent imposed voltage pulse and time-dependent thermal boundary conditions on the transient supercooling behavior as well as the response of characteristic time and cold-junction temperature distribution to the pulse operation parameters during the periods of pulse start-up, pulse-on time, and pulse-off time, which is served as a theoretical basis for exploiting the coupling interaction of the thermoelectric effects on the heat diffusion from or to the cold junction interrelated with the amount of the availably electrical conversion in the short time scale. Additionally, the advantage of certain pulse forms over others is described. The results indicate that Peltier supercooling capacity shows a decreasing monotonic trend in proportion to the total amount of electrical conversion, and the maximum coefficient of performance for cooling state is about 0.5 to be achieved at steady state. Taking advantage of the temporary Peltier effect focused electrical conversion as the additional cooling for a period long enough against the earlier arrival of the excessively Joule heating dominated heat accumulation is the key parameter

  16. Evidence for a liquid-liquid critical point in supercooled water within the E3B3 model and a possible interpretation of the kink in the homogeneous nucleation line

    Science.gov (United States)

    Ni, Yicun; Skinner, J. L.

    2016-06-01

    Supercooled water exhibits many thermodynamic anomalies, and several scenarios have been proposed to interpret them, among which the liquid-liquid critical point (LLCP) hypothesis is the most commonly discussed. We investigated Widom lines and the LLCP of deeply supercooled water, by using molecular dynamics simulation with a newly reparameterized water model that explicitly includes three-body interactions. Seven isobars are studied from ambient pressure to 2.5 kbar, and Widom lines are identified by calculating maxima in the coefficient of thermal expansion and the isothermal compressibility (both with respect to temperature). From these data we estimate that the LLCP of the new water model is at 180 K and 2.1 kbar. The oxygen radial distribution function is calculated along the 2 kbar isobar. It shows a steep change in the height of its second peak between 180 and 185 K, which indicates a transition between the high-density liquid and low-density liquid phases and which is consistent with the ascribed location of the critical point. The good agreement of the height of the second peak of the radial distribution function between simulation and experiment at 1 bar, as a function of temperature, supports the validity of the model. The location of the LLCP within the model is close to the kink in the experimental homogeneous nucleation line. We use existing experimental data to argue that the experimental LLCP is at 168 K and 1.95 kbar and speculate how this LLCP and its Widom line might be responsible for the kink in the homogeneous nucleation line.

  17. Evidence for a liquid-liquid critical point in supercooled water within the E3B3 model and a possible interpretation of the kink in the homogeneous nucleation line.

    Science.gov (United States)

    Ni, Yicun; Skinner, J L

    2016-06-07

    Supercooled water exhibits many thermodynamic anomalies, and several scenarios have been proposed to interpret them, among which the liquid-liquid critical point (LLCP) hypothesis is the most commonly discussed. We investigated Widom lines and the LLCP of deeply supercooled water, by using molecular dynamics simulation with a newly reparameterized water model that explicitly includes three-body interactions. Seven isobars are studied from ambient pressure to 2.5 kbar, and Widom lines are identified by calculating maxima in the coefficient of thermal expansion and the isothermal compressibility (both with respect to temperature). From these data we estimate that the LLCP of the new water model is at 180 K and 2.1 kbar. The oxygen radial distribution function is calculated along the 2 kbar isobar. It shows a steep change in the height of its second peak between 180 and 185 K, which indicates a transition between the high-density liquid and low-density liquid phases and which is consistent with the ascribed location of the critical point. The good agreement of the height of the second peak of the radial distribution function between simulation and experiment at 1 bar, as a function of temperature, supports the validity of the model. The location of the LLCP within the model is close to the kink in the experimental homogeneous nucleation line. We use existing experimental data to argue that the experimental LLCP is at 168 K and 1.95 kbar and speculate how this LLCP and its Widom line might be responsible for the kink in the homogeneous nucleation line.

  18. Entropy calculations for a supercooled liquid crystalline blue phase

    Energy Technology Data Exchange (ETDEWEB)

    Singh, U [Physics Department, University of the West Indies, PO Box 64, Bridgetown (Barbados)

    2007-01-15

    We observed, using polarized light microscopy, the supercooling of the blue phase (BPI) of cholesteryl proprionate and measured the corresponding liquid crystalline phase transition temperatures. From these temperatures and additional published data we have provided, for the benefit of undergraduate physics students, a nontraditional example involving entropy calculations for an irreversible transition.

  19. Temperature measurement of supercooled droplet in icing phenomenon by means of dual-luminescent imaging

    Science.gov (United States)

    Tanaka, M.; Morita, K.; Mamori, H.; Fukushima, N.; Yamamoto, M.

    2017-08-01

    The collision of a supercooled water droplet with a surface result an object creates ice accretion on the surface. The icing problem in any cold environments leads to severe damages on aircrafts, and a lot of studies on prevention and prediction techniques for icing have been conducted so far. Therefore, it is very important to know the detail of freezing mechanism of supercooled water droplets to improve the anti-and de-icing devices and icing simulation codes. The icing mechanism of a single supercooled water droplet impacting on an object surface would give us great insights for the purpose. In the present study, we develop a dual-luminescent imaging technique to measure the time-resolved temperature of a supercooled water droplet impacting on the surface under different temperature conditions. We apply this technique to measure the exact temperature of a water droplet, and to discuss the detail of the freezing process.

  20. Thermal conductivity enhancement of sodium acetate trihydrate by adding graphite powder and the effect on stability of supercooling

    DEFF Research Database (Denmark)

    Johansen, Jakob Berg; Dannemand, Mark; Kong, Weiqiang

    2015-01-01

    Sodium acetate trihydrate and graphite powder mixtures have been evaluated to investigate the influence of the graphite powder on the stability of supercooling. A sodium acetate and water mixture mixed with graphite powder was successfully supercooled at ambient indoor temperatures for five month...

  1. Factors contributing to deep supercooling capability and cold survival in dwarf bamboo (Sasa senanensis leaf blades.

    Directory of Open Access Journals (Sweden)

    Masaya eIshikawa

    2015-01-01

    Full Text Available Wintering Sasa senanensis, dwarf bamboo, has been known to employ deep supercooling as the mechanism of cold hardiness in its most of the tissues from leaves to rhizomes. The unique cold hardiness mechanism of this plant was further characterized using current year leaf blades. Cold hardiness levels increased from August (LT20: –11 °C to December (LT20: –20 °C, which coincided with the initiation temperature of low temperature exotherms (LTE detected in differential thermal analyses. When leaf blades were stored at –5 °C for 1-14 days, there was no nucleation of the supercooled tissue units compartmentalized by the longitudinal and transverse veins either in summer or winter. However, only summer leaves suffered significant injury after prolonged supercooling of the tissue units. This may be a novel type of low temperature-induced injury in supercooled state at subfreezing temperatures. When winter leaf blades were maintained at the threshold temperature (-20 °C, a longer storage period (1-7 days increased lethal freezing of the supercooled tissue units. Within a wintering shoot, the second or third leaf blade from the top was most cold hardy and leaf blades at lower positions tended to suffer more injury due to lethal freezing of the supercooled units, which was not correlated with the leaf water content. LTE were shifted to higher temperatures (2-5 °C after a lethal freeze-thaw cycle. The results demonstrate that the tissue unit compartmentalized with longitudinal and transverse veins serves as the unit of supercooling and temperature- and time-dependent freezing of the units is lethal both in laboratory freeze tests and in the field. To establish such supercooling in the unit, structural ice barriers such as development of sclerenchyma and biochemical mechanisms to increase the stability of supercooling are considered important. We discussed these mechanisms in regard to ecological and physiological significance in winter survival.

  2. Fragile to strong crossover at the Widom line in supercooled aqueous solutions of NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Gallo, P. [Dipartimento di Matematica e Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Rome, Italy and INFN, Sezione di Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy); Corradini, D.; Rovere, M., E-mail: rovere@fis.uniroma3.it [Dipartimento di Matematica e Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Rome (Italy)

    2013-11-28

    We study by molecular dynamics simulations the dynamical properties of an aqueous solution of NaCl at a concentration of 0.67 mol/kg upon supercooling. In a previous study of the same ionic solution, we have located the liquid-liquid critical point (LLCP) and determined the Widom line connected to the liquid-liquid transition. We present here the results obtained from the study of the self-intermediate scattering function in a large range of temperatures and densities approaching the LLCP. The structural relaxation is in agreement with the mode coupling theory (MCT) in the region of mild supercooling. In the deeper supercooled region the α-relaxation time as function of temperature deviates from the MCT power law prediction showing a crossover from a fragile to a strong behavior. This crossover is found upon crossing the Widom line. The same trend was found in bulk water upon supercooling and it appears almost unchanged by the interaction with ions apart from a shift in the thermodynamic plane toward lower pressures and higher temperatures. These results show that the phenomenology of supercooled water transfers from bulk to solution where the study of the supercooled region is experimentally less difficult.

  3. Fragile to strong crossover at the Widom line in supercooled aqueous solutions of NaCl.

    Science.gov (United States)

    Gallo, P; Corradini, D; Rovere, M

    2013-11-28

    We study by molecular dynamics simulations the dynamical properties of an aqueous solution of NaCl at a concentration of 0.67 mol/kg upon supercooling. In a previous study of the same ionic solution, we have located the liquid-liquid critical point (LLCP) and determined the Widom line connected to the liquid-liquid transition. We present here the results obtained from the study of the self-intermediate scattering function in a large range of temperatures and densities approaching the LLCP. The structural relaxation is in agreement with the mode coupling theory (MCT) in the region of mild supercooling. In the deeper supercooled region the α-relaxation time as function of temperature deviates from the MCT power law prediction showing a crossover from a fragile to a strong behavior. This crossover is found upon crossing the Widom line. The same trend was found in bulk water upon supercooling and it appears almost unchanged by the interaction with ions apart from a shift in the thermodynamic plane toward lower pressures and higher temperatures. These results show that the phenomenology of supercooled water transfers from bulk to solution where the study of the supercooled region is experimentally less difficult.

  4. Supercooling and cold energy storage characteristics of nano-media in ball-packed porous structures

    Directory of Open Access Journals (Sweden)

    Zhao Qunzhi

    2015-04-01

    Full Text Available The presented experiments aimed to study the supercooling and cold-energy storage characteristics of nanofluids and water-based nano-media in ball-packed porous structures (BPS. Titanium dioxide nanoparticles (TiO2 NPs measuring 20nm and 80nm were used as additives and sodium dodecyl benzene sulphonate (SDBS was used as anionic surfactant. The experiments used different concentrations of nanofluid, distilled with BPS of different spherical diameter and different concentrations of nano-media, and were conducted 20 times. Experimental results of supercooling were analysed by statistical methods. Results show that the average and peak supercooling degrees of nanofluids and nano-media in BPS are lower than those of distilled water. For the distilled water in BPS, the supercooling degree decreases on the whole with the decrease of the ball diameter. With the same spherical diameter (8mm of BPS, the supercooling degree of TiO2 NPs measuring 20nm is lower than the supercooling degree of distilled water in BPS. Step-cooling experiments of different concentrations of nanofluids and nano-media in BPS were also conducted. Results showed that phase transition time is reduced because of the presence of TiO2 NPs. The BPS substrate and the NPs enhance the heat transfer. Distilled water with a porous solid base and nanoparticles means the amount of cold-energy storage increases and the supercooling degree and the total time are greatly reduced. The phase transition time of distilled water is about 3.5 times that of nano-media in BPS.

  5. Experimental evidence for supercooled brines, viscous liquids, and low temperature perchlorate glasses on Mars

    Science.gov (United States)

    Toner, J.; Catling, D. C.; Light, B.

    2013-12-01

    The presence of liquid water on the cold and dry surface of Mars is possible where concentrated salt solutions lower the freezing point of water. The eutectic temperature is the maximum equilibrium freezing point depression possible for a given salt solution, which ranges from near 0°C for carbonates and sulfates, to as low as -75°C for perchlorates. Although eutectic temperatures suggest a lower temperature limit for liquid water on Mars, salt solutions will typically supercool below their eutectic before crystallization occurs. We report on results investigating the magnitude of supercooling and its variation with salt composition and concentration for pure salt solutions and saturated soil solutions of MgSO4, MgCl2, NaCl, NaClO4, Mg(ClO4)2, and Ca(ClO4)2. We measured supercooling by monitoring solution temperatures during slow cooling and warming experiments. Our results indicate that supercooling is pervasive. Slowly cooled MgSO4, MgCl2, NaCl, and NaClO4 solutions typically supercool 5-15°C below their eutectic temperature before crystallizing. The addition of soil to these salt solutions has a variable effect on supercooling. Relative to the pure salt solutions, supercooling decreases in MgSO4 soil solutions, increases in MgCl2 soil solutions, and is similar in NaCl and NaClO4 soil solutions. Supercooling in MgSO4, MgCl2, NaCl, and NaClO4 solutions could marginally extend the duration of liquid water during relatively warm daytime temperatures in the Martian summer. Remarkably, we found that Mg(ClO4)2 and Ca(ClO4)2 solutions never crystallize during slow cooling, but remain in a supercooled, liquid state until forming an amorphous glass near -120°C. Even if soil is added to the solutions, which will induce crystallization in most salt solutions, a glass still forms during cooling. The large supercooling effect in Mg(ClO4)2 and Ca(ClO4)2 solutions has the potential to prevent water from freezing over diurnal and possibly annual cycles on Mars. Glasses are

  6. Strain Pattern in Supercooled Liquids

    Science.gov (United States)

    Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

    2016-11-01

    Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

  7. Quasielastic and inelastic neutron scattering investigation of fragile-to-strong crossover in deeply supercooled water confined in nanoporous silica matrices

    Energy Technology Data Exchange (ETDEWEB)

    Liu Li [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Chen, S-H [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Faraone, Antonio [NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899 (United States); Yen, C-W [Department of Chemistry, National Taiwan University, Taipei, Taiwan (China); Mou, C-Y [Department of Chemistry, National Taiwan University, Taipei, Taiwan (China); Kolesnikov, Alexander I [Intense Pulsed Neutron Source Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Mamontov, Eugene [NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899 (United States); Leao, Juscelino [NIST Center for Neutron Research, NIST, Gaithersburg, MD 20899 (United States)

    2006-09-13

    We investigated, using quasi-elastic and inelastic neutron scattering, the slow single-particle dynamics of water confined in laboratory synthesized nanoporous silica matrices, MCM-41-S, with pore diameters ranging from 10 to 18 A. Inside the pores of these matrices, the freezing process of water is strongly inhibited down to 160 K. We analysed the quasi-elastic part of the neutron scattering spectra with a relaxing-cage model and determined the temperature and pressure dependence of the Q-dependent translational relaxation time and its stretch exponent {beta} for the time dependence of the self-intermediate scattering function. The calculated Q-independent average translational relaxation time shows a fragile-to-strong (FS) dynamic crossover for pressures lower than 1600 bar. Above this pressure, it is no longer possible to discern the characteristic feature of the FS crossover. Identification of this end point with the predicted second low-temperature critical point of water is discussed. A subsequent inelastic neutron scattering investigation of the librational band of water indicates that this FS dynamic crossover is associated with a structural change of the hydrogen-bond cage surrounding a typical water molecule from a denser liquid-like configuration to a less-dense ice-like open structure.

  8. Experimental investigations on cylindrical latent heat storage units with sodium acetate trihydrate composites utilizing supercooling

    DEFF Research Database (Denmark)

    Dannemand, Mark; Johansen, Jakob Berg; Kong, Weiqiang;

    2016-01-01

    unit was tested with 116.3 kg SAT with 0.5% Xanthan rubber as a thickening agent and 4.4% graphite powder. The heat exchange capacity rate during charge was significantly lower for the unit with SAT and Xanthan rubber compared to the unit with SAT and extra water. This was due to less convection......Latent heat storage units utilizing stable supercooling of sodium acetate trihydrate (SAT) composites were tested in a laboratory. The stainless steel units were 1.5 m high cylinders with internal heat exchangers of tubes with fins. One unit was tested with 116 kg SAT with 6% extra water. Another...... in the thickened phase change material after melting. The heat content in the fully charged state and the heat released after solidification of the supercooled SAT mixtures at ambient temperature was higher for the unit with the thickened SAT mixture. The heat discharged after solidification of the supercooled SAT...

  9. A phase space approach to supercooled liquids and a universal collapse of their viscosity

    Directory of Open Access Journals (Sweden)

    Nicholas Bryan Weingartner

    2016-11-01

    Full Text Available A broad fundamental understanding of the mechanisms underlying the phenomenology of supercooled liquids has remained elusive, despite decades of intense exploration. When supercooled beneath its characteristic melting temperature, a liquid sees a sharp rise in its viscosity over a narrow temperature range, eventually becoming frozen on laboratory timescales. Explaining this immense increase in viscosity is one of the principle goals of condensed matter physicists. To that end, numerous theoretical frameworks have been proposed which explain and reproduce the temperature dependence of the viscosity of supercooled liquids. Each of these frameworks appears only applicable to specific classes of glassformers and each possess a number of variable parameters. Here we describe a classical framework for explaining the dynamical behavior of supercooled liquids based on statistical mechanical considerations, and possessing only a single variable parameter. This parameter varies weakly from liquid to liquid. Furthermore, as predicted by this new classical theory and its earlier quantum counterpart, we find with the aid of a small dimensionless constant that varies in size from sim 0.05-0.12 , a universal (16 decade collapse of the viscosity data as a function of temperature. The collapse appears in all known types of glass forming supercooled liquids (silicates, metallic alloys, organic systems, chalcogenide, sugars, and water.

  10. A phase space approach to supercooled liquids and a universal collapse of their viscosity

    Science.gov (United States)

    Weingartner, Nicholas; Nogueira, Flavio; Pueblo, Chris; Kelton, Kenneth; Nussinov, Zohar

    2016-11-01

    A broad fundamental understanding of the mechanisms underlying the phenomenology of supercooled liquids has remained elusive, despite decades of intense exploration. When supercooled beneath its characteristic melting temperature, a liquid sees a sharp rise in its viscosity over a narrow temperature range, eventually becoming frozen on laboratory timescales. Explaining this immense increase in viscosity is one of the principle goals of condensed matter physicists. To that end, numerous theoretical frameworks have been proposed which explain and reproduce the temperature dependence of the viscosity of supercooled liquids. Each of these frameworks appears only applicable to specific classes of glassformers and each possess a number of variable parameters. Here we describe a classical framework for explaining the dynamical behavior of supercooled liquids based on statistical mechanical considerations, and possessing only a single variable parameter. This parameter varies weakly from liquid to liquid. Furthermore, as predicted by this new classical theory and its earlier quantum counterpart, we find with the aid of a small dimensionless constant that varies in size from ˜ 0.05-0.12, a universal (16 decade) collapse of the viscosity data as a function of temperature. The collapse appears in all known types of glass forming supercooled liquids (silicates, metallic alloys, organic systems, chalcogenide, sugars, and water).

  11. Experimental investigations on heat content of supercooled sodium acetate trihydrate by a simple heat loss method

    DEFF Research Database (Denmark)

    Kong, Weiqiang; Dannemand, Mark; Johansen, Jakob Berg

    2016-01-01

    Sodium acetate trihydrate is a phase change material that can be used for long term heat storage in solar heating systems because of its relatively high heat of fusion, a melting temperature of 58 °C and its ability to supercool stable. In practical applications sodium acetate trihydrate tend...... to suffer from phase separation which is the phenomenon where anhydrous salt settles to the bottom over time. This happens especially in supercooled state. The heat released from the crystallization of supercooled sodium acetate trihydrate with phase separation will be lower than the heat released from...... sodium acetate trihydrate without phase separation. Possible ways of avoiding or reducing the problem of phase separation were investigated. A wide variety of composites of sodium acetate trihydrate with additives including extra water, thickening agents, solid and liquid polymers have been...

  12. The formation of supercooled brines, viscous liquids, and low-temperature perchlorate glasses in aqueous solutions relevant to Mars

    Science.gov (United States)

    Toner, J. D.; Catling, D. C.; Light, B.

    2014-05-01

    Salt solutions on Mars can stabilize liquid water at low temperatures by lowering the freezing point of water. The maximum equilibrium freezing-point depression possible, known as the eutectic temperature, suggests a lower temperature limit for liquid water on Mars; however, salt solutions can supercool below their eutectic before crystallization occurs. To investigate the magnitude of supercooling and its variation with salt composition and concentration, we performed slow cooling and warming experiments on pure salt solutions and saturated soil-solutions of MgSO4, MgCl2, NaCl, NaClO4, Mg(ClO4)2, and Ca(ClO4)2. By monitoring solution temperatures, we identified exothermic crystallization events and determined the composition of precipitated phases from the eutectic melting temperature. Our results indicate that supercooling is pervasive. In general, supercooling is greater in more concentrated solutions and with salts of Ca and Mg. Slowly cooled MgSO4, MgCl2, NaCl, and NaClO4 solutions investigated in this study typically supercool 5-15 °C below their eutectic temperature before crystallizing. The addition of soil to these salt solutions has a variable effect on supercooling. Relative to the pure salt solutions, supercooling decreases in MgSO4 soil-solutions, increases in MgCl2 soil-solutions, and is similar in NaCl and NaClO4 soil-solutions. Supercooling in MgSO4, MgCl2, NaCl, and NaClO4 solutions could marginally extend the duration of liquid water during relatively warm daytime temperatures in the martian summer. In contrast, we find that Mg(ClO4)2 and Ca(ClO4)2 solutions do not crystallize during slow cooling, but remain in a supercooled, liquid state until forming an amorphous glass near -120 °C. Even if soil is added to the solutions, a glass still forms during cooling. The large supercooling effect in Mg(ClO4)2 and Ca(ClO4)2 solutions has the potential to prevent water from freezing over diurnal and possibly annual cycles on Mars. Glasses are also

  13. Operationalising active involvement in the EU water framework directive

    DEFF Research Database (Denmark)

    Wright, Stuart Anthony Lewis; Fritsch, Oliver

    2011-01-01

    of actively involving non-state actors, which can be summarised as increasing the effectiveness of policy and improving its implementation. Criticising the emerging economic decision-making approach, we argue that economic analyses could result in a missed opportunity to capitalise on the potential benefits...... to comply with the statutory requirements of the Directive, but should strive for active involvement due to the potential for increasing the effectiveness of the Water Framework Directive and improving its implementation......We identify two key stages in the river basin planning process under the Water Framework Directive: the selection of instruments for a programme of measures to achieve the environmental targets, and disproportionate cost analysis to determine whether selected measures involve high costs. Some EU...

  14. Mechanism of supercooling in flower bud of Camellia oleifea

    Institute of Scientific and Technical Information of China (English)

    苏维埃; 潘良文

    1995-01-01

    It is the first time for MRI to be used in the research of flower buds supercooling. Directobservation on freezing course of living flower buds of Camellia yuhsienensis by MRI and tissue browning test showed that freezing order of the flower organs is bud axis, scale, petal, pistil and stamen. It is coincident with the direction of ice development from bud axes to flower organs upwards. The corresponding results from MRI and freezing-fixation showed that the water translocation from flower organs to axes and scales is carried on in the course of bud freezing. ’H spectral measurement of NMR was used to follow the decrease of unfrozen water in the buds during the cooling.

  15. Gelation on heating of supercooled gelatin solutions.

    Science.gov (United States)

    Guigo, Nathanaël; Sbirrazzuoli, Nicolas; Vyazovkin, Sergey

    2012-04-23

    Diluted (1.0-1.5 wt%) aqueous gelatin solutions have been cooled to -10 °C at a cooling rate 20 °C min(-1) without freezing and detectable gelation. When heated at a constant heating rate (0.5 -2 °C min(-1)), the obtained supercooled solutions demonstrate an atypical process of gelation that has been characterized by regular and stochastically modulated differential scanning calorimetry (DSC) as well as by isoconversional kinetic analysis. The process is detectable as an exothermic peak in the total heat flow of regular DSC and in the nonreversing heat flow of stochastically modulated DSC. Isoconversional kinetic analysis applied to DSC data reveals that the effective activation energy of the process increases from approximately 75 to 200 kJ mol(-1) as a supercooled solution transforms to gel on continuous heating.

  16. Fractional Walden rule for electrolytes in supercooled disaccharide aqueous solutions.

    Science.gov (United States)

    Longinotti, M Paula; Corti, Horacio R

    2009-04-23

    The electrical conductivity of CsCl, KCl, Bu(4)NBr, and Bu(4)NI was studied in stable and supercooled (metastable) sucrose and trehalose aqueous solutions over a wide viscosity range. The results indicate that large positive deviations from the Walden rule occur in these systems due to the higher tendency of the ions to move in water-rich regions, as previously observed for NaCl and MgCl(2). The electrical molar conductivity viscosity dependence can be described with a fractional Walden rule (Lambdaeta(alpha) = constant), where alpha is a decoupling parameter which increases with ionic size and varies between 0.61 and 0.74 for all of the studied electrolytes. Using the electrical molar conductivity dependence of ion-ion interactions, an effective dielectric constant was calculated for a trehalose 39 wt% aqueous solution as a function of temperature. Above 278 K, the effective and the bulk solution dielectric constants are similar, but at lower temperatures, where the carbohydrate becomes less mobile than water, the effective dielectric constant approaches the dielectric constant of water. We also conclude that the solute-solvent dielectric friction contribution can be neglected, reinforcing the idea that the observed breakdown of the Walden rule is due to the existence of local microheterogeneities. The Walden plots for the studied ionic solutes show a decoupling similar to that found for the diffusion of water in the same solutions.

  17. The Common Occurrence of Highly Supercooled Drizzle and Rain near the Coastal Regions of the Western United States

    Energy Technology Data Exchange (ETDEWEB)

    Rosenfeld, Daniel; Chemke, Rei; DeMott, Paul J.; Sullivan, Ryan C.; Rasmussen, R M.; McDonough, Frank; Comstock, Jennifer M.; Schmid, Beat; Tomlinson, Jason M.; Jonsson, Haf; Suski, Kaitlyn; Cazorla, Alberto; Prather, Kimberly

    2013-09-05

    The formation of highly supercooled rain was documented by aircraft observations in clouds at a wide range of conditions near the coastal region of the western United States. Several case studies are described in detail using combined cloud and aerosol measurements to document both the highly super-cooled condition and the relatively pristine aerosol conditions under which it forms. The case studies include: (1) Marine convective clouds over the coastal waters of northern California, as measured by cloud physics probes flown on a Gulfstream-1 aircraft during the CALWATER campaign in February and early March 2011. The clouds had extensive drizzle in their tops, which extended downward to the 0°C isotherm as supercooled rain. Ice multiplication was observed only in mature parts of the clouds where cloud water was already depleted. (2) Orographically triggered convective clouds in marine air mass over the foothills of the Sierra Nevada to the east of Sacramento, as measured in CALWATER. Supercooled rain was observed down to -21°C. No indications for ice multiplication were evident. (3) Orographic layer clouds over Yosemite National Park, also measured in CALWATER. The clouds had extensive drizzle at -21°C, which intensified with little freezing lower in the cloud, and (4) Supercooled drizzle drops in layer clouds near Juneau, Alaska, as measured by the Wyoming King Air as part of a FAA project to study aircraft icing in this region. Low concentrations of CCN was a common observation in all these clouds, allowing for the formation of clouds with small concentration of large drops that coalesced into supercooled drizzle and raindrops. Another common observation was the absence of ice nuclei and/or ice crystals in measurable concentrations was associated with the persistent supercooled drizzle and rain. Average ice crystal concentrations were 0.007 l-1 at the top of convective clouds at -12°C and 0.03 l-1 in the case of layer clouds at -21°C. In combination these

  18. The Dutch dominant perspective on water: risks and opportunities involved.

    Science.gov (United States)

    Offermans, Astrid; Valkering, Pieter; Vreugdenhil, Heleen; Wijermans, Nanda; Haasnoot, Marjolijn

    2013-01-01

    To implement or continue water management strategies social support is needed. Social support highly depends on people's perspectives on water. However, these perspectives are not static and may change over time leading to changes in social support for strategies. Therefore, sustainable water management strategies should be robust. Robust strategies are able to cope with changing social and environmental developments. Lacking robustness runs the risk of losing social support, which may force policymakers into sudden or expensive measures. We use the Perspectives Method to analyze the present Dutch policy perspective and the dominant perspective on water among Dutch water professionals, by respectively studying the Dutch Delta report and questionnaire outputs and distinguishing between Hierarchical, Egalitarian, Individualistic and Fatalistic perspectives. A comparison between the policy and professional perspective shows similarities and differences. Topics regarding drought, water supply, and waters' relation to spatial planning need serious reconsideration to guarantee enough present and future social support to implement the measures suggested in the policy report.

  19. Experimental investigations on prototype heat storage units utilizing stable supercooling of sodium acetate trihydrate mixtures

    DEFF Research Database (Denmark)

    Dannemand, Mark; Dragsted, Janne; Fan, Jianhua;

    2016-01-01

    was filled with 220 kg SAT mixture thickened with 1% carboxymethyl cellulose. The heat exchange capacity rate during the charging of the unit with the extra water was significantly higher than for the unit with the thickening agent due to the different levels of convection. The SAT mixtures in the units were......Laboratory tests of two heat storage units based on the principle of stable supercooling of sodium acetate trihydrate (SAT) mixtures were carried out. One unit was filled with 199.5 kg of SAT with 9% extra water to avoid phase separation of the incongruently melting salt hydrate. The other unit...

  20. Transcriptomic and proteomic analyses on the supercooling ability and mining of antifreeze proteins of the Chinese white wax scale insect.

    Science.gov (United States)

    Yu, Shu-Hui; Yang, Pu; Sun, Tao; Qi, Qian; Wang, Xue-Qing; Chen, Xiao-Ming; Feng, Ying; Liu, Bo-Wen

    2016-06-01

    The Chinese white wax scale insect, Ericerus pela, can survive at extremely low temperatures, and some overwintering individuals exhibit supercooling at temperatures below -30°C. To investigate the deep supercooling ability of E. pela, transcriptomic and proteomic analyses were performed to delineate the major gene and protein families responsible for the deep supercooling ability of overwintering females. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that genes involved in the mitogen-activated protein kinase, calcium, and PI3K-Akt signaling pathways and pathways associated with the biosynthesis of soluble sugars, sugar alcohols and free amino acids were dominant. Proteins responsible for low-temperature stress, such as cold acclimation proteins, glycerol biosynthesis-related enzymes and heat shock proteins (HSPs) were identified. However, no antifreeze proteins (AFPs) were identified through sequence similarity search methods. A random forest approach identified 388 putative AFPs in the proteome. The AFP gene ep-afp was expressed in Escherichia coli, and the expressed protein exhibited a thermal hysteresis activity of 0.97°C, suggesting its potential role in the deep supercooling ability of E. pela.

  1. Signal transduction pathways involved in intestinal salt and water secretion

    NARCIS (Netherlands)

    W. van den Berghe (Nina)

    1992-01-01

    textabstractThis thesis describes some novel aspects of the regulation of salt and water secretion in the intestinal epithelium. This process is not unique for the intestine, but a common and necessary function of many other organs, including the stomach (gastric juice), kidney (urine), sweatglands

  2. On the potential energy landscape of supercooled liquids and glasses

    DEFF Research Database (Denmark)

    Rodney, D.; Schrøder, Thomas

    2011-01-01

    The activation-relaxation technique (ART), a saddle-point search method, is applied to determine the potential energy landscape around supercooled and glassy configurations of a three-dimensional binary Lennard-Jones system. We show a strong relation between the distribution of activation energies...... around a given glassy configuration and its history, in particular, the cooling rate used to produce the glass and whether or not the glass was plastically deformed prior to sampling. We also compare the thermally activated transitions found by ART around a supercooled configuration with the succession...... of transitions undergone by the same supercooled liquid during a time trajectory simulated by molecular dynamics. We find that ART is biased towards more heterogeneous transitions with higher activation energies and more broken bonds than the MD simulation....

  3. Turbulent heat transfer as a control of platelet ice growth in supercooled under-ice ocean boundary layers

    Science.gov (United States)

    McPhee, Miles G.; Stevens, Craig L.; Smith, Inga J.; Robinson, Natalie J.

    2016-04-01

    Late winter measurements of turbulent quantities in tidally modulated flow under land-fast sea ice near the Erebus Glacier Tongue, McMurdo Sound, Antarctica, identified processes that influence growth at the interface of an ice surface in contact with supercooled seawater. The data show that turbulent heat exchange at the ocean-ice boundary is characterized by the product of friction velocity and (negative) water temperature departure from freezing, analogous to similar results for moderate melting rates in seawater above freezing. Platelet ice growth appears to increase the hydraulic roughness (drag) of fast ice compared with undeformed fast ice without platelets. Platelet growth in supercooled water under thick ice appears to be rate-limited by turbulent heat transfer and that this is a significant factor to be considered in mass transfer at the underside of ice shelves and sea ice in the vicinity of ice shelves.

  4. Using Peltier cells to study solid-liquid-vapour transitions and supercooling

    Energy Technology Data Exchange (ETDEWEB)

    Torzo, Giacomo [ICIS-CNR and Physics Department of Padova University, Padova (Italy); Soletta, Isabella [Liceo Scientifico Fermi, Alghero (Italy); Branca, Mario [Chemical Department of Sassari University, Sassari (Italy)

    2007-05-15

    We propose an apparatus for teaching experimental thermodynamics in undergraduate introductory courses, using thermoelectric modules and a real-time data acquisition system. The device may be made at low cost, still providing an easy approach to the investigation of liquid-solid and liquid-vapour phase transitions and of metastable states (supercooling). The thermoelectric module (a technological evolution of the thermocouple) is by itself an interesting subject that offers a clear example of both thermo-electric (Seebeck effect) and electro-thermal (Peltier effect) energy transformation. We report here some cooling/heating measurements for several liquids and mixtures, including water, salt/water, ethanol/water and sodium acetate, showing how to evaluate the phenomena of freezing point depression and elevation, and how to evaluate the water latent heat.

  5. Using Peltier cells to study solid liquid vapour transitions and supercooling

    Science.gov (United States)

    Torzo, Giacomo; Soletta, Isabella; Branca, Mario

    2007-05-01

    We propose an apparatus for teaching experimental thermodynamics in undergraduate introductory courses, using thermoelectric modules and a real-time data acquisition system. The device may be made at low cost, still providing an easy approach to the investigation of liquid solid and liquid vapour phase transitions and of metastable states (supercooling). The thermoelectric module (a technological evolution of the thermocouple) is by itself an interesting subject that offers a clear example of both thermo-electric (Seebeck effect) and electro-thermal (Peltier effect) energy transformation. We report here some cooling/heating measurements for several liquids and mixtures, including water, salt/water, ethanol/water and sodium acetate, showing how to evaluate the phenomena of freezing point depression and elevation, and how to evaluate the water latent heat.

  6. Hopping in a supercooled binary Lennard-Jones liquid

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Dyre, Jeppe

    1998-01-01

    A binary Lennard–Jones liquid has been investigated by molecular dynamics at equilibrium supercooled conditions. At the lowest temperature investigated, hopping is present in the system as indicated by a secondary peak in 4r2Gs(r,t), where Gs(r,t) is the van Hove self correlation function...

  7. Modelling skin surface areas involved in water transfer in the Palmate Newt (Lissotriton helveticus)

    National Research Council Canada - National Science Library

    Wardziak, Thomas; Oxarango, Laurent; Valette, Sebastien; Mahieu-Williame, Laurent; Joly, Pierre

    2014-01-01

    Magnetic resonance imaging (MRI) based 3D reconstructions were used to derive accurate quantitative data on body volume and functional skin surface areas involved in water transfer in the Palmate Newt...

  8. Thermodynamic and structural characterization of the transformation from a metastable low-density to a very high-density form of supercooled TIP4P-Ew model water.

    Science.gov (United States)

    Paschek, Dietmar; Rüppert, Andreas; Geiger, Alfons

    2008-12-22

    We explore the phase diagram of the metastable TIP4P-Ew liquid model water from 360 K down to 150 K at densities ranging from 0.950 to 1.355 g cm(-3). In addition to the low-density/high-density (LDL/HDL) liquid-liquid transition, we observe a structural high-density/very high-density (HDL/VHDL) transformation for the lowest temperatures at 1.30 g cm(-3). The characteristics of the isobars and isotherms suggest the presence of a stepwise HDL/VHDL transition with first-order-like appearance. In addition, we also identify an apparent pretransition at 1.24 g cm(-3), which suggests that the experimentally detected LDA/VHDA transformation might evolve into a multiple-step process with different local structures representing local minima in the free-energy landscape. Such a scenario is supported by a pronounced correlation between the isothermal density dependence of the pressure, with a stepwise increase of the oxygen coordination number, due to the appearance of interstitial water molecules.

  9. Numerical investigation on super-cooled large droplet icing of fan rotor blade in jet engine

    Science.gov (United States)

    Isobe, Keisuke; Suzuki, Masaya; Yamamoto, Makoto

    2014-10-01

    Icing (or ice accretion) is a phenomenon in which super-cooled water droplets impinge and accrete on a body. It is well known that ice accretion on blades and vanes leads to performance degradation and has caused severe accidents. Although various anti-icing and deicing systems have been developed, such accidents still occur. Therefore, it is important to clarify the phenomenon of ice accretion on an aircraft and in a jet engine. However, flight tests for ice accretion are very expensive, and in the wind tunnel it is difficult to reproduce all climate conditions where ice accretion can occur. Therefore, it is expected that computational fluid dynamics (CFD), which can estimate ice accretion in various climate conditions, will be a useful way to predict and understand the ice accretion phenomenon. On the other hand, although the icing caused by super-cooled large droplets (SLD) is very dangerous, the numerical method has not been established yet. This is why SLD icing is characterized by splash and bounce phenomena of droplets and they are very complex in nature. In the present study, we develop an ice accretion code considering the splash and bounce phenomena to predict SLD icing, and the code is applied to a fan rotor blade. The numerical results with and without the SLD icing model are compared. Through this study, the influence of the SLD icing model is numerically clarified.

  10. Ice-lens formation and geometrical supercooling in soils and other colloidal materials

    CERN Document Server

    Style, Robert W; Cocks, Alan C F; Wettlaufer, John S

    2011-01-01

    We present a new, physically-intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil. At low temperatures, ice in the crack exerts large pressures on the crack walls that will eventually cause the crack to split open. We show that the crack will then propagate across the soil to form a new lens. The process is controlled by two factors: the cohesion of the soil, and the geometrical supercooling of the water in the soil; a new concept introduced to measure the energy available to form a new ice lens. When the supercooling exceeds a critical amount (proportional to the cohesive strength of the soil) a new ice lens forms. This condition for ice-lens formation and growth does not appeal to any ad hoc, empirical assumptions, and explains how periodic ice lenses can form with or without the presence of a frozen fringe. The proposed mechanism is in good ...

  11. Generation of live offspring from vitrified embryos with synthetic polymers SuperCool X-1000 and SuperCool Z-1000.

    Science.gov (United States)

    Marco-Jimenez, F; Jimenez-Trigos, E; Lavara, R; Vicente, J S

    2014-01-01

    Ice growth and recrystallisation are considered important factors in determining vitrification outcomes. Synthetic polymers inhibit ice formation during cooling or warming of the vitrification process. The aim of this study was to assess the effect of adding commercially available synthetic polymers SuperCool X-1000 and SuperCool Z-1000 to vitrification media on in vivo development competence of rabbit embryos. Four hundred and thirty morphologically normal embryos recovered at 72 h of gestation were used. The vitrification media contained 20% dimethyl sulphoxide and 20% ethylene glycol, either alone or in combination with 1% of SuperCool X-1000 and 1% SuperCool. Our results show that embryos can be successfully vitrified using SuperCool X-1000 and SuperCool Z-1000 and when embryos are transferred, live offspring can be successfully produced. In conclusion, our results demonstrated that we succeeded for the first time in obtaining live offspring after vitrification of embryos using SuperCool X-1000 and SuperCool Z-1000 polymers.

  12. Improvements of the experimental apparatus for measurement of the surface tension of supercooled liquids using horizontal capillary tube

    Directory of Open Access Journals (Sweden)

    Vinš Václav

    2016-01-01

    Full Text Available An experimental apparatus with a horizontal capillary tube for measurement of the surface tension of supercooled liquids, i.e. liquids in a metastable state below the equilibrium freezing point, was designed and tested in the previous study [V. Vinš et al., EPJ Web Conf. 92, 02108 (2015]. In this work, recent modifications of both the experimental setup and the measurement analysis are described. The main aim is to improve the accuracy and the reproducibility of measured surface tension and to achieve higher degrees of supercooling. Temperature probes measuring the temperature of cooling medium near the horizontal capillary tube were calibrated in the relevant temperature range from – 31 °C to + 45 °C. An additional pressure transducer was installed in the helium distribution setup at the position close to the capillary tube. The optical setup observing the liquid meniscus at the open end of the horizontal capillary tube together with the video analysis were thoroughly revised. The red laser illuminating the liquid meniscus, used at the original apparatus, was replaced by a fiber optic light source, which significantly improved the quality of the meniscus image. The modified apparatus was used for the measurement of surface tension of supercooled water at temperatures down to – 11 °C. The new data have a lower scatter compared to the previous horizontal measurements and show a good agreement with the other data obtained with a different measurement technique based on the modified capillary rise method.

  13. Discrimination of micrometre-sized ice and super-cooled droplets in mixed-phase cloud

    Science.gov (United States)

    Hirst, E.; Kaye, P. H.; Greenaway, R. S.; Field, P.; Johnson, D. W.

    Preliminary experimental results are presented from an aircraft-mounted probe designed to provide in situ data on cloud particle shape, size, and number concentration. In particular, the probe has been designed to facilitate discrimination between super-cooled water droplets and ice crystals of 1-25 μm size within mixed-phase clouds and to provide information on cloud interstitial aerosols. The probe acquires spatial light scattering data from individual particles at throughput rates of several thousand particles per second. These data are logged at 100 ms intervals to allow the distribution and number concentration of each particle type to be determined with 10 m spatial resolution at a typical airspeed of 100 m s -1. Preliminary results from flight data recorded in altocumulus castellanus, showing liquid water phase, mixed phase, and ice phase are presented to illustrate the probe's particle discrimination capabilities.

  14. Shear-accelerated crystallization in a supercooled atomic liquid.

    Science.gov (United States)

    Shao, Zhen; Singer, Jonathan P; Liu, Yanhui; Liu, Ze; Li, Huiping; Gopinadhan, Manesh; O'Hern, Corey S; Schroers, Jan; Osuji, Chinedum O

    2015-02-01

    A bulk metallic glass forming alloy is subjected to shear flow in its supercooled state by compression of a short rod to produce a flat disk. The resulting material exhibits enhanced crystallization kinetics during isothermal annealing as reflected in the decrease of the crystallization time relative to the nondeformed case. The transition from quiescent to shear-accelerated crystallization is linked to strain accumulated during shear flow above a critical shear rate γ̇(c)≈0.3 s(-1) which corresponds to Péclet number, Pe∼O(1). The observation of shear-accelerated crystallization in an atomic system at modest shear rates is uncommon. It is made possible here by the substantial viscosity of the supercooled liquid which increases strongly with temperature in the approach to the glass transition. We may therefore anticipate the encounter of nontrivial shear-related effects during thermoplastic deformation of similar systems.

  15. Mixing effects in the crystallization of supercooled quantum binary liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kühnel, M.; Kalinin, A. [Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); Fernández, J. M.; Tejeda, G.; Moreno, E.; Montero, S. [Laboratory of Molecular Fluid Dynamics, Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid (Spain); Tramonto, F.; Galli, D. E. [Laboratorio di Calcolo Parallelo e di Simulazioni di Materia Condensata, Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Nava, M. [Laboratorio di Calcolo Parallelo e di Simulazioni di Materia Condensata, Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Computational Science, Department of Chemistry and Applied Biosciences, ETH Zurich, USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano (Switzerland); Grisenti, R. E. [Institut für Kernphysik, J. W. Goethe-Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); GSI - Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt (Germany)

    2015-08-14

    By means of Raman spectroscopy of liquid microjets, we have investigated the crystallization process of supercooled quantum liquid mixtures composed of parahydrogen (pH{sub 2}) or orthodeuterium (oD{sub 2}) diluted with small amounts of neon. We show that the introduction of the Ne impurities affects the crystallization kinetics in terms of a significant reduction of the measured pH{sub 2} and oD{sub 2} crystal growth rates, similarly to what found in our previous work on supercooled pH{sub 2}-oD{sub 2} liquid mixtures [Kühnel et al., Phys. Rev. B 89, 180201(R) (2014)]. Our experimental results, in combination with path-integral simulations of the supercooled liquid mixtures, suggest in particular a correlation between the measured growth rates and the ratio of the effective particle sizes originating from quantum delocalization effects. We further show that the crystalline structure of the mixtures is also affected to a large extent by the presence of the Ne impurities, which likely initiate the freezing process through the formation of Ne-rich crystallites.

  16. Guidelines for inclusion: Ensuring Indigenous peoples' involvement in water planning processes across South Eastern Australia

    Science.gov (United States)

    Saenz Quitian, Alejandra; Rodríguez, Gloria Amparo

    2016-11-01

    Indigenous peoples within the Murray-Darling Basin have traditionally struggled for the recognition of their cultural, social, environmental, spiritual, commercial and economic connection to the waters that they have traditionally used, as well as their right to engage in all stages of water planning processes. Despite Australian national and federal frameworks providing for the inclusion of Indigenous Australians' objectives in planning frameworks, water plans have rarely addressed these objectives in water, or the strategies to achieve them. Indeed, insufficient resources, a lack of institutional capacity in both Indigenous communities and agencies and an inadequate understanding of Indigenous people's objectives in water management have limited the extent to which Indigenous objectives are addressed in water plans within the Murray-Darling Basin. In this context, the adoption of specific guidelines to meet Indigenous requirements in relation to basin water resources is crucial to support Indigenous engagement in water planning processes. Using insights from participatory planning methods and human rights frameworks, this article outlines a set of alternative and collaborative guidelines to improve Indigenous involvement in water planning and to promote sustainable and just water allocations.

  17. Observations of ice multiplication in a weakly convective cell embedded in supercooled mid-level stratus

    Directory of Open Access Journals (Sweden)

    J. Crosier

    2010-08-01

    Full Text Available Simultaneous observations of cloud microphysical properties were obtained by in-situ aircraft measurements and ground based Radar/Lidar. Widespread mid-level stratus cloud was present below a temperature inversion (~5 °C magnitude at 3.6 km altitude. Localised convection (peak updraft 1.5 m s−1 was observed 20 km west of the Radar station. This was associated with convergence at 2.5 km altitude. The convection was unable to penetrate the inversion capping the mid-level stratus.

    The mid-level stratus cloud was vertically thin (~400 m, horizontally extensive (covering 100 s of km and persisted for more than 24 h. The cloud consisted of supercooled water droplets and small concentrations of large (~1 mm stellar/plate like ice which slowly precipitated out. This ice was nucleated at temperatures greater than −12.2 °C and less than −10.0 °C, (cloud top and cloud base temperatures, respectively. No ice seeding from above the cloud layer was observed. This ice was formed by primary nucleation, either through the entrainment of efficient ice nuclei from above/below cloud, or by the slow stochastic activation of immersion freezing ice nuclei contained within the supercooled drops. Above cloud top significant concentrations of sub-micron aerosol were observed and consisted of a mixture of sulphate and carbonaceous material, a potential source of ice nuclei.

    Precipitation from the mid-level stratus evaporated before reaching the surface, whereas rates of up to 1 mm h−1 were observed below the convective feature. There is strong evidence for the Hallett-Mossop (HM process of secondary ice particle production leading to the formation of the precipitation observed. This includes (1 Ice concentrations in the convective feature were more than an order of magnitude greater than the concentration of primary ice in the overlaying stratus, (2 Large concentrations of small pristine columns were observed at the ~−5

  18. Involvement of aquaporin channels in water extrusion from biosilica during maturation of sponge siliceous spicules.

    Science.gov (United States)

    Wang, Xiaohong; Müller, Werner E G

    2015-08-01

    Aquaporins are a family of small, pore-forming, integral cell membrane proteins. This ancient protein family functions as water channels and is found in all kingdoms (including archaea, eubacteria, fungi, plants, and animals). We discovered that in sponges aquaporin plays a novel role during the maturation of spicules, their skeletal elements. Spicules are synthesized enzymatically via silicatein following a polycondensation reaction. During this process, a 1:1 stoichiometric release of water per one Si-O-Si bond formed is produced. The product of silicatein, biosilica, is a fluffy, soft material that must be hardened in order to function as a solid rod. Using the model of the demosponge species Suberites domuncula Olivi, 1792, which expresses aquaporin, cDNA was cloned and the protein was heterologously expressed. The sponge aquaporin is grouped with the type 8 aquaporins. The function of the sponge aquaporin can be blocked by Mn-sulfate (MnSO4) and mercury chloride (HgCl2). Microscopic and functional studies suggest that aquaporin is involved in removal of the reaction water at the site where siliceous spicules are formed. Another molecule that is likely to be involved in biosilica maturation is the mucin/nidogen-like polypeptide. cDNA has also been cloned from S. domuncula. Experimental studies suggest that water extrusion/suctioning from biosilica after enzymatic synthesis during spicule formation involves both aquaporin-mediated water channeling and "polymerization-induced phase separation" facilitated by the mucin/nidogen-like polypeptide.

  19. Long term thermal energy storage with stable supercooled sodium acetate trihydrate

    DEFF Research Database (Denmark)

    Dannemand, Mark; Schultz, Jørgen M.; Johansen, Jakob Berg

    2015-01-01

    it expands and will cause a pressure built up in a closed chamber which might compromise stability of the supercooling. This can be avoided by having an air volume above the phase change material connected to an external pressure less expansion tank. Supercooled sodium acetate trihydrate at 20 °C stores up...

  20. Supercooling of rapidly expanding quark-gluon plasma

    CERN Document Server

    Zabrodin, E E; Csernai, László P; Stöcker, H; Greiner, W

    1998-01-01

    We reexamine the scenario of homogeneous nucleation of the quark-gluon plasma produced in ultra-relativistic heavy ion collisions. A generalization of the standard nucleation theory to rapidly expanding system is proposed. The nucleation rate is derived via the new scaling parameter $\\lambda_Z$. It is shown that the size distribution of hadronic clusters plays an important role in the dynamics of the phase transition. The longitudinally expanding system is supercooled to about 3-6%, then it is reheated, and the hadronization is completed within 6-10 fm/c, i.e. 5-10 times faster than it was estimated earlier, in a strongly nonequilibrium way.

  1. Hopping in a supercooled binary Lennard-Jones liquid

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Dyre, Jeppe

    1998-01-01

    A binary Lennard–Jones liquid has been investigated by molecular dynamics at equilibrium supercooled conditions. At the lowest temperature investigated, hopping is present in the system as indicated by a secondary peak in 4r2Gs(r,t), where Gs(r,t) is the van Hove self correlation function....... To examine the dynamics of the system, we consider transitions between the inherent structures (local minima in the potential energy) along the trajectory. We conclude that the plateau in the mean square displacement found at lower temperatures is indeed a result of particles being trapped in local "cages...

  2. The freezing and supercooling of garlic (Allium sativum L.)

    Energy Technology Data Exchange (ETDEWEB)

    James, Christian; Seignemartin, Violaine; James, Stephen J. [Food Refrigeration and Process Engineering Research Centre (FRPERC), University of Bristol, Churchill Building, Langford, Bristol BS40 5DU (United Kingdom)

    2009-03-15

    This work shows that peeled garlic cloves demonstrate significant supercooling during freezing under standard conditions and can be stored at temperatures well below their freezing point (-2.7 C) without freezing. The nucleation point or 'metastable limit temperature' (the point at which ice crystal nucleation is initiated) of peeled garlic cloves was found to be between -7.7 and -14.6 C. Peeled garlic cloves were stored under static air conditions at temperatures between -6 and -9 C for up to 69 h without freezing, and unpeeled whole garlic bulbs and cloves were stored for 1 week at -6 C without freezing. (author)

  3. Successful vitrification of mouse ovaries using less-concentrated cryoprotectants with Supercool X-1000 supplementation.

    Science.gov (United States)

    Tan, Xiuwen; Song, Enliang; Liu, Xiaomu; Liu, Guifen; Cheng, Haijian; Wan, Fachun

    2012-02-01

    The purpose of our study was to investigate the feasibility of using less-concentrated cryoprotectants supplemented with ice blocker Supercool X-1000 to vitrify ovarian tissues. Mouse ovaries were cryopreserved in different concentrations of vitrification solution alone or with Supercool X-1000, and fresh non-frozen ovaries were used as control. The proportions of morphological normality of follicles, normal GCs in follicular fluids and developing to blastocysts were higher in 12.5% ethylene glycol (EG) + 12.5% dimethylsulfoxide (DMSO) with Supercool X-1000 than those of treated in 10% EG + 10% DMSO or 15% EG + 15% DMSO alone or with Supercool X-1000. In conclusion, the inclusion of Supercool X-1000 in less-concentrated vitrification solution was effective to improve the efficiency and efficacy of cryopreservation of ovarian tissues.

  4. Detection of Weak Radiation Involving Generation and Progress of Water Tree

    Science.gov (United States)

    Kumazawa, Takao; Taniguchi, Ryouichi

    It is well known that generation and progress of water tree in XLPE cable are remarkably influenced by inorganic impurities. We have investigated the behavior of them in water tree and reported the experimental results as follows: i) the anomalous increase or decrease in several kinds of inorganic elements was observed in water treed XLPE samples, ii) a distinctive relationship was found for the mass numbers for the elements, iii) the isotopic content of the elements such as Zn deviated over 6% from the natural abundance. These results suggest that water tree is concerned with unknown phenomena e.g., cold fusion or nuclear transmutation in condensed matter. In order to study the relationship between water tree and these phenomena, we attempted to detect neutron, γ-ray or X-ray involving generation and progress of water tree in XLPE samples. For the experiments weak and burst-like radiation seemed to be low energy γ-ray or X-ray was often detected by BF3 and/or CdZnTe counter. The radiation tended to be detected from the samples in which a lot of water trees were generated by supplying inorganic cations abundantly.

  5. Ice-lens formation and geometrical supercooling in soils and other colloidal materials

    KAUST Repository

    Style, Robert W.

    2011-10-14

    We present a physically intuitive model of ice-lens formation and growth during the freezing of soils and other dense, particulate suspensions. Motivated by experimental evidence, we consider the growth of an ice-filled crack in a freezing soil. At low temperatures, ice in the crack exerts large pressures on the crack walls that will eventually cause the crack to split open. We show that the crack will then propagate across the soil to form a new lens. The process is controlled by two factors: the cohesion of the soil and the geometrical supercooling of the water in the soil, a new concept introduced to measure the energy available to form a new ice lens. When the supercooling exceeds a critical amount (proportional to the cohesive strength of the soil) a new ice lens forms. This condition for ice-lens formation and growth does not appeal to any ad hoc, empirical assumptions, and explains how periodic ice lenses can form with or without the presence of a frozen fringe. The proposed mechanism is in good agreement with experiments, in particular explaining ice-lens pattern formation and surges in heave rate associated with the growth of new lenses. Importantly for systems with no frozen fringe, ice-lens formation and frost heave can be predicted given only the unfrozen properties of the soil. We use our theory to estimate ice-lens growth temperatures obtaining quantitative agreement with the limited experimental data that are currently available. Finally we suggest experiments that might be performed in order to verify this theory in more detail. The theory is generalizable to complex natural-soil scenarios and should therefore be useful in the prediction of macroscopic frost-heave rates. © 2011 American Physical Society.

  6. Electrostatic levitation studies of supercooled liquids and metastable solid phases

    Science.gov (United States)

    Rustan, Gustav Errol

    A new laboratory has been developed at Iowa State University (ISU) to be used for the study of high temperature liquids and solids, with particular focus on the supercooling of liquids and their metastable solidification products. This new laboratory employs the electrostatic levitation (ESL) technique, in which a charged sample is suspended between a set of electrodes to achieve non-contact handling. Owing to the elimination of a crucible, high temperature processing of samples can be achieved with reduced levels of contamination and heterogeneous nucleation. Because of the reduction in heterogeneous nucleation, samples can be supercooled well below their equilibrium melting temperature, opening the door to a wide range of measurements on supercooled liquids. Measurements methods have been implemented for the characterization of thermophysical properties such as: volume/density, ratio of specific heat to total hemispherical emissivity, surface tension, viscosity, electrical resistivity, and magnetic susceptibility. For measurements of electrical resistivity and magnetic susceptibility, a new method has been developed at ISU based on the tunnel diode oscillator (TDO) technique. The TDO technique uses the negative differential resistance of a tunnel diode to drive an LC tank circuit into self-sustained oscillation at the resonant LC frequency. The LC tank is inductively coupled to the samples under study, and changes in the electrical resistivity or magnetic susceptibility of the sample are manifested as changes in the resonant frequency. By measuring the frequency shifts of the TDO, insights can be made into changes in the material's electrical and magnetic properties. This method has been validated by performing resistivity measurements on a sample of high purity Zr, and by performing measurements on the ferromagnetic transition in a low-carbon steel ball bearing. In addition to the development of the laboratory and its supporting instrumentation, an effort has

  7. Factors involved in alleviating water stress by partial crop removal in pear trees.

    Science.gov (United States)

    Marsal, Jordi; Mata, Merce; Arbones, Amadeu; Del Campo, Jesus; Girona, Joan; Lopez, Gerardo

    2008-09-01

    We studied the relief of water stress associated with fruit thinning in pear (Pyrus communis L.) trees during drought to determine what mechanisms, other than stomatal adjustment, were involved. Combinations of control irrigation (equal to crop water use less effective rainfall) and deficit irrigation (equal to 20% of control irrigation), fruit load (unthinned and thinned to 40 fruits per tree) and root pruning (pruned and unpruned) treatments were applied to pear (cv. 'Conference') trees during Stage II of fruit development. Daily patterns of midday stem water potential (Psi(stem)) and leaf conductance to water vapor (g(l)) of deficit-irrigated trees differed after fruit thinning. In response to fruit thinning, gl progressively declined with water stress until 30 days after fruit thinning and then leveled off, whereas the effects of decreased fruit load on Psi(stem) peaked 30-40 days after fruit thinning and then tended to decline. Soil water depletion was significantly correlated with fruit load during drought. Our results indicate that stomatal adjustment and the resulting soil water conservation were the factors determining the Psi(stem) response to fruit thinning. However, these factors could not explain differences in daily patterns between g(l) and Psi(stem) after fruit thinning. In all cases, effects of root pruning treatments on Psi(stem) in deficit-irrigated trees were transitory (Psi(stem) recovered from root pruning in less than 30 days), but the recovery of Psi(stem) after root pruning was faster in trees with low fruit loads. This behavior is compatible with the concept that the water balance (reflected by Psi(stem) values) was better in trees with low fruit loads compared with unthinned trees, perhaps because more carbon was available for root growth. Thus, a root growth component is hypothesized as a mechanism to explain the bimodal Psi(stem) response to fruit thinning during drought.

  8. Persistent Supercooling of Reproductive Shoots Is Enabled by Structural Ice Barriers Being Active Despite an Intact Xylem Connection

    Science.gov (United States)

    Pfaller, Kristian; Wagner, Johanna

    2016-01-01

    Extracellular ice nucleation usually occurs at mild subzero temperatures in most plants. For persistent supercooling of certain plant parts ice barriers are necessary to prevent the entry of ice from already frozen tissues. The reproductive shoot of Calluna vulgaris is able to supercool down to below -22°C throughout all developmental stages (shoot elongation, flowering, fruiting) despite an established xylem conductivity. After localization of the persistent ice barrier between the reproductive and vegetative shoot at the base of the pedicel by infrared differential thermal analysis, the currently unknown structural features of the ice barrier tissue were anatomically analyzed on cross and longitudinal sections. The ice barrier tissue was recognized as a 250 μm long constriction zone at the base of the pedicel that lacked pith tissue and intercellular spaces. Most cell walls in this region were thickened and contained hydrophobic substances (lignin, suberin, and cutin). A few cell walls had what appeared to be thicker cellulose inclusions. In the ice barrier tissue, the area of the xylem was as much as 5.7 times smaller than in vegetative shoots and consisted of tracheids only. The mean number of conducting units in the xylem per cross section was reduced to 3.5% of that in vegetative shoots. Diameter of conducting units and tracheid length were 70% and 60% (respectively) of that in vegetative shoots. From vegetative shoots water transport into the ice barrier must pass pit membranes that are likely impermeable to ice. Pit apertures were about 1.9 μm x 0.7 μm, which was significantly smaller than in the vegetative shoot. The peculiar anatomical features of the xylem at the base of the pedicel suggest that the diameter of pores in pit membranes could be the critical constriction for ice propagation into the persistently supercooled reproductive shoots of C. vulgaris. PMID:27632365

  9. The role of agency goals and local context in Great Lakes water resources public involvement programs

    Science.gov (United States)

    Landre, Betsy Kiernan; Knuth, Barbara A.

    1993-03-01

    As complex social phenomena, public involvement processes are influenced by contextual factors. This study examined agency goals for public involvement and assessed the importance of local context in remedial action planning, a community-based water resources program aimed at the cleanup of the 42 most polluted locations in the Great Lakes Basin. Agency goals for public involvement in remedial action plans (RAPs) were agency-oriented and focused on public acceptance of the plan, support for implementation, and positive agency-public relations. Corresponding to these goals, citizen advisory committees were created in 75% of the RAP sites as a primary means for public input into the planning process. Factors that influenced the implementation of public involvement programs in remedial action planning included public orientation toward the remediation issue, local economic conditions, the interaction of diverse interests in the process, agency and process credibility, experience of local leadership, and jurisdictional complexity. A formative assessment of “community readiness” appeared critical to appropriate public involvement program design. Careful program design may also include citizen education and training components, thoughtful management of ongoing agency-public relations and conflict among disparate interests in the process, overcoming logistical difficulties that threaten program continuity, using local expertise and communication channels, and circumventing interjurisdictional complexities.

  10. Central muscarinic receptor subtypes involved in pilocarpine-induced salivation, hypertension and water intake.

    Science.gov (United States)

    Borella, T L; De Luca, L A; Colombari, D S A; Menani, J V

    2008-12-01

    Recent evidence has suggested that pilocarpine (ACh receptor agonist) injected peripherally may act centrally producing salivation and hypertension. In this study, we investigated the effects of specific M(1) (pirenzepine), M(2)/M(4) (methoctramine), M(1)/M(3) (4-DAMP) and M(4) (tropicamide) muscarinic receptor subtype antagonists injected into the lateral cerebral ventricle (LV) on salivation, water intake and pressor responses to peripheral pilocarpine. Male Holtzman rats with stainless steel cannulae implanted in the LV were used. Salivation was measured in rats anaesthetized with ketamine (100 mg per kg body weight) and arterial pressure was recorded in unanaesthetized rats. Salivation induced by i.p. pilocarpine (4 micromol per kg body weight) was reduced only by 4-DAMP (25-250 nmol) injected into the LV, not by pirenzepine, methoctramine or tropicamide at the dose of 500 nmol. Pirenzepine (0.1 and 1 nmol) and 4-DAMP (5 and 10 nmol) injected into the LV reduced i.p. pilocarpine-induced water intake, whereas metoctramine (50 nmol) produced nonspecific effects on ingestive behaviours. Injection of pirenzepine (100 nmol) or 4-DAMP (25 and 50 nmol) into the LV reduced i.v. pilocarpine-induced pressor responses. Tropicamide (500 nmol) injected into the LV had no effect on pilocarpine-induced salivation, pressor responses or water intake. The results suggest that central M(3) receptors are involved in peripheral pilocarpine-induced salivation and M(1) receptors in water intake and pressor responses. The involvement of M(3) receptors in water intake and pressor responses is not clear because 4-DAMP blocks both M(1) and M(3) receptors.

  11. Photophysics and electrochemistry relevant to photocatalytic water splitting involved at solid–electrolyte interfaces

    KAUST Repository

    Shinagawa, Tatsuya

    2016-08-04

    Direct photon to chemical energy conversion using semiconductor-electrocatalyst-electrolyte interfaces has been extensively investigated for more than a half century. Many studies have focused on screening materials for efficient photocatalysis. Photocatalytic efficiency has been improved during this period but is not sufficient for industrial commercialization. Detailed elucidation on the photocatalytic water splitting process leads to consecutive six reaction steps with the fundamental parameters involved: The photocatalysis is initiated involving photophysics derived from various semiconductor properties (1: photon absorption, 2: exciton separation). The generated charge carriers need to be transferred to surfaces effectively utilizing the interfaces (3: carrier diffusion, 4: carrier transport). Consequently, electrocatalysis finishes the process by producing products on the surface (5: catalytic efficiency, 6: mass transfer of reactants and products). Successful photocatalytic water splitting requires the enhancement of efficiency at each stage. Most critically, a fundamental understanding of the interfacial phenomena is highly desired for establishing "photocatalysis by design" concepts, where the kinetic bottleneck within a process is identified by further improving the specific properties of photocatalytic materials as opposed to blind material screening. Theoretical modeling using the identified quantitative parameters can effectively predict the theoretically attainable photon-conversion yields. This article provides an overview of the state-of-the-art theoretical understanding of interfacial problems mainly developed in our laboratory. Photocatalytic water splitting (especially hydrogen evolution on metal surfaces) was selected as a topic, and the photophysical and electrochemical processes that occur at semiconductor-metal, semiconductor-electrolyte and metal-electrolyte interfaces are discussed.

  12. Effects of Artificial Supercooling Followed by Slow Freezing on the Microstructure and Qualities of Pork Loin

    OpenAIRE

    Kim, Yiseul; Hong, Geun-Pyo

    2016-01-01

    This study investigated the effects of artificial supercooling followed by still air freezing (SSF) on the qualities of pork loin. The qualities of pork frozen by SSF were compared with the fresh control (CT, stored at 4℃ for 24 h), slow freezing (SAF, still air freezing) and rapid freezing (EIF, ethanol immersion freezing) treatments. Compared with no supercooling phenomena of SAF and EIF, the extent of supercooling obtained by SSF treatment was 1.4℃. Despite that SSF was conducted with the ...

  13. A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yuntao [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Dibble, Collin J. [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Petrik, Nikolay G. [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Smith, R. Scott [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Joly, Alan G. [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Tonkyn, Russell G. [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Kay, Bruce D. [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA; Kimmel, Greg A. [Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA

    2016-04-26

    A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond timescale in ultrahigh vacuum (UHV). Details of the design, implementation and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ~1010 K/s for temperature increases of ~100 – 200 K are obtained. Subsequent rapid cooling (~5 × 109 K/s) quenches the film, permitting in-situ, post-mortem analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ~ ± 3% leading to a temperature uncertainty of ~ ± 5 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces.

  14. 2H NMR studies of supercooled and glassy aspirin

    Science.gov (United States)

    Nath, R.; Nowaczyk, A.; Geil, B.; Bohmer, R.

    2007-11-01

    Acetyl salicylic acid, deuterated at the methyl group, was investigated using 2H-NMR in its supercooled and glassy states. Just above the glass transition temperature the molecular reorientations were studied using stimulated-echo spectroscopy and demonstrated a large degree of similarity with other glass formers. Deep in the glassy phase the NMR spectra look similar to those reported for the crystal [A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z. Olejniczak, Z. T. Lalowicz, Z. Naturforsch. A 50 (1995) 95] and below 20 K they are indicative for rotational tunneling with a relatively large tunneling frequency. Measurements of the spin-lattice relaxation times for temperatures below 150 K reveal a broad distribution of correlation times in the glass. The dominant energy barrier characterizing the slow-down of the methyl group is significantly smaller than the well defined barrier in the crystal.

  15. Different Bacterial Communities Involved in Peptide Decomposition between Normoxic and Hypoxic Coastal Waters

    Science.gov (United States)

    Liu, Shuting; Wawrik, Boris; Liu, Zhanfei

    2017-01-01

    Proteins and peptides are key components of the labile dissolved organic matter pool in marine environments. Knowing which types of bacteria metabolize peptides can inform the factors that govern peptide decomposition and further carbon and nitrogen remineralization in marine environments. A 13C-labeled tetrapeptide, alanine-valine-phenylalanine-alanine (AVFA), was added to both surface (normoxic) and bottom (hypoxic) seawater from a coastal station in the northern Gulf of Mexico for a 2-day incubation experiment, and bacteria that incorporated the peptide were identified using DNA stable isotope probing (SIP). The decomposition rate of AVFA in the bottom hypoxic seawater (0.018–0.035 μM h-1) was twice as fast as that in the surface normoxic seawater (0.011–0.017 μM h-1). SIP experiments indicated that incorporation of 13C was highest among the Flavobacteria, Sphingobacteria, Alphaproteobacteria, Acidimicrobiia, Verrucomicrobiae, Cyanobacteria, and Actinobacteria in surface waters. In contrast, highest 13C-enrichment was mainly observed in several Alphaproteobacteria (Thalassococcus, Rhodobacteraceae, Ruegeria) and Gammaproteobacteria genera (Colwellia, Balneatrix, Thalassomonas) in the bottom water. These data suggest that a more diverse group of both oligotrophic and copiotrophic bacteria may be involved in metabolizing labile organic matter such as peptides in normoxic coastal waters, and several copiotrophic genera belonging to Alphaproteobacteria and Gammaproteobacteria and known to be widely distributed may contribute to faster peptide decomposition in the hypoxic waters. PMID:28326069

  16. Dynamical Instability Causes the Demise of a Supercooled Tetrahedral Liquid

    Science.gov (United States)

    Gautam, Arvind Kumar; Pingua, Nandlal; Goyal, Aashish; Apte, Pankaj A.

    2017-09-01

    We investigate the relaxation mechanism of a supercooled tetrahedral liquid at its limit of stability using isothermal isobaric ( NPT) Monte Carlo simulations. In similarity with systems which are far from equilibrium but near the onset of jamming (O'Hern et al. in Phys Rev Lett 93:165702, 2004), we find that the relaxation is characterized by two time-scales: the decay of long-wavelength (slow) fluctuations of potential energy is controlled by the slope [partial (G/N)/partial φ ] of the Gibbs free energy ( G) at a unique value of per particle potential energy φ = φ _{{\\tiny mid}}. The short-wavelength (fast) fluctuations are controlled by the bath temperature T. The relaxation of the supercooled liquid is initiated with a dynamical crossover after which the potential energy fluctuations are biased towards values progressively lesser than φ _{{\\tiny mid}}. The dynamical crossover leads to the change of time-scale, i.e., the decay of long-wavelength potential energy fluctuations (intermediate stage of relaxation). Because of the condition [partial ^2 (G/N)/partial φ ^2 = 0] at φ = φ _{{\\tiny mid}}, the slope [partial (G/N)/partial φ ] has a unique value and governs the intermediate stage of relaxation, which ends just after the crossover. In the subsequent stage, there is a relatively rapid crystallization due to lack of long-wavelength fluctuations and the instability at φ _{{\\tiny mid}}, i.e., the condition that G decreases as configurations with potential energies lower than φ _{{\\tiny mid}} are accessed. The dynamical crossover point and the associated change in the time-scale of fluctuations is found to be consistent with the previous studies.

  17. Identification of a novel gene (Hsdr4) involved in water-stress tolerance in wild barley.

    Science.gov (United States)

    Suprunova, Tatiana; Krugman, Tamar; Distelfeld, Assaf; Fahima, Tzion; Nevo, Eviatar; Korol, Abraham

    2007-05-01

    Drought is one of the most severe stresses limiting plant growth and yield. Genes involved in water stress tolerance of wild barley (Hordeum spontaneoum), the progenitor of cultivated barley, were investigated using genotypes contrasting in their response to water stress. Gene expression profiles of water-stress tolerant vs. water-stress sensitive wild barley genotypes, under severe dehydration stress applied at the seedling stage, were compared using cDNA-AFLP analysis. Of the 1100 transcript-derived fragments (TDFs) amplified about 70 displayed differential expression between control and stress conditions. Eleven of them showed clear difference (up- or down-regulation) between tolerant and susceptible genotypes. These TDFs were isolated, sequenced and tested by RT-PCR. The differential expression of seven TDFs was confirmed by RT-PCR, and TDF-4 was selected as a promising candidate gene for water-stress tolerance. The corresponding gene, designated Hsdr4 (Hordeum spontaneum dehydration-responsive), was sequenced and the transcribed and flanking regions were determined. The deduced amino acid sequence has similarity to the rice Rho-GTPase-activating protein-like with a Sec14 p-like lipid-binding domain. Analysis of Hsdr4 promoter region that was isolated by screening a barley BAC library, revealed a new putative miniature inverted-repeat transposable element (MITE), and several potential stress-related binding sites for transcription factors (MYC, MYB, LTRE, and GT-1), suggesting a role of the Hsdr4 gene in plant tolerance to dehydration stress. Furthermore, the Hsdr4 gene was mapped using wild barley mapping population to the long arm of chromosome 3H between markers EBmac541 and EBmag705, within a region that previously was shown to affect osmotic adaptation in barley.

  18. REDOX CHEMISTRY OF MOLYBDENUM IN NATURAL WATERS AND ITS INVOLVEMENT IN BIOLOGICAL EVOLUTION

    Directory of Open Access Journals (Sweden)

    Deli eWang

    2012-12-01

    Full Text Available The transition element molybdenum (Mo possesses diverse valances (+II to +VI, and is involved in forming cofactors in more than 60 enzymes in biology. Redox switching of the element in these enzymes catalyzes a series of metabolic reactions in both prokaryotes and eukaryotes, and the element therefore plays a fundamental role in the global carbon, nitrogen, and sulfur cycling. In the present oxygenated waters, oxidized Mo(VI predominates thermodynamically, whilst reduced Mo species are mainly confined within specific niches including cytoplasm. Only recently has the reduced Mo(V been separated from Mo(VI in sulfidic mats and even in some reducing waters. Given the presence of reduced Mo(V in contemporary anaerobic habitats, it seems that reduced Mo species were present in the ancient reducing ocean (probably under both ferrigenous and sulfidic conditions, prompting the involvement of Mo in enzymes including nitrogenase and nitrate reductase. During the global transition to oxic conditions, reduced Mo species were constrained to specific anaerobic habitats, and efficient uptake systems of oxidized Mo(VI became a selective advantage both for prokaryotic and eukaryotic cells. Some prokaryotes are still able to directly utilize reduced Mo if any exists in ambient environments. In total, this mini-review describes the redox chemistry and biogeochemistry of Mo over the Earth’s history.

  19. A phase space approach to supercooled liquids and a universal collapse of their viscosity

    CERN Document Server

    Weingartner, Nicholas B; Nogueira, Flavio S; Kelton, K F; Nussinov, Zohar

    2016-01-01

    A broad fundamental understanding of the mechanisms underlying the phenomenology of supercooled liquids has remained elusive, despite decades of intense exploration. When supercooled beneath its characteristic melting temperature, a liquid sees a sharp rise in its viscosity over a narrow temperature range, eventually becoming frozen on laboratory timescales. Explaining this immense increase in viscosity is one of the principle goals of condensed matter physicists. To that end, numerous theoretical frameworks have been proposed which explain and reproduce the temperature dependence of the viscosity of supercooled liquids. Each of these frameworks appears only applicable to specific classes of glassformers and each possess a number of variable parameters. Here we describe a classical framework for explaining the dynamical behavior of supercooled liquids based on statistical mechanical considerations, and possessing only a single variable parameter. This parameter varies weakly from liquid to liquid. Furthermore...

  20. Microphysical Effects of Cloud Seeding in Supercooled Stratiform Clouds Observed from NOAA Satellite

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the satellite retrieval methodology, the spectral characteristics and cloud microphysical properties were analyzed that included brightness temperatures of Channels 4 and 5, and their brightness temperature difference (BTD), the particle effective radius of seeded cloud track caused by an operational cloud seeding and the microphysical effects of cloud seeding were revealed by the comparisons of their differences inside and outside the seeded track. The cloud track was actually a cloud channel reaching 1.5-km deep and 14-km wide lasting for more than 80 min. The effective radius of ambient clouds was 10-15μm, while that within the cloud track ranged from 15 to 26 μm. The ambient clouds were composed of supercooled droplets, and the composition of the cloud within the seeding track was ice. With respect to the rather stable reflectance of two ambient sides around the track, the visible spectral reflectance in the cloud track varied at least 10%, and reached a maximum of 35%, the reflectance of 3.7 μm in the seeded track relatively decreased at least 10%. As cloud seeding advanced, the width and depth were gradually increased. Simultaneously the cloud top temperature within the track became progressively warmer with respect to the ambient clouds,and the maximum temperature differences reached 4.2 and 3.9℃ at the first seeding position for Channels 4 and 5. In addition, the BTD in the track also increased steadily to a maximum of 1.4℃, compared with 0.2-0.4℃ of the ambient clouds. The evidence that the seeded cloud became thinner comes from the visible image showing a channel, the warming of the cloud tops, and the increase of BTD in the seeded track.The seeded cloud became thinner mainly because the cloud top descended and it lost water to precipitation throughout its depth. For this cloud seeding case, the glaciation became apparent at cloud tops about 22min after seeding. The formation of a cloud track in the supercooled stratiform clouds was

  1. Detection and Analysis of High Ice Concentration Events and Supercooled Drizzle from IAGOS Commercial Aircraft

    Science.gov (United States)

    Gallagher, Martin; Baumgardner, Darrel; Lloyd, Gary; Beswick, Karl; Freer, Matt; Durant, Adam

    2016-04-01

    Hazardous encounters with high ice concentrations that lead to temperature and airspeed sensor measurement errors, as well as engine rollback and flameout, continue to pose serious problems for flight operations of commercial air carriers. Supercooled liquid droplets (SLD) are an additional hazard, especially for smaller commuter aircraft that do not have sufficient power to fly out of heavy icing conditions or heat to remove the ice. New regulations issued by the United States and European regulatory agencies are being implemented that will require aircraft below a certain weight class to carry sensors that will detect and warn of these types of icing conditions. Commercial aircraft do not currently carry standard sensors to detect the presence of ice crystals in high concentrations because they are typical found in sizes that are below the detection range of aircraft weather radar. Likewise, the sensors that are currently used to detect supercooled water do not respond well to drizzle-sized drops. Hence, there is a need for a sensor that can fill this measurement void. In addition, the forecast models that are used to predict regions of icing rely on pilot observations as the only means to validate the model products and currently there are no forecasts for the prevalence of high altitude ice crystals. Backscatter Cloud Probes (BCP) have been flying since 2011 under the IAGOS project on six Airbus commercial airliners operated by Lufthansa, Air France, China Air, Iberia and Cathay Pacific, and measure cloud droplets, ice crystals and aerosol particles larger than 5 μm. The BCP can detect these particles and measures an optical equivalent diameter (OED) but is not able to distinguish the type of particle, i.e. whether they are droplets, ice crystals, dust or ash. However, some qualification can be done based on measured temperature to discriminate between liquid water and ice. The next generation BCP (BCPD, Backscatter Cloud Probe with polarization detection) is

  2. Observations of ice multiplication in a weakly convective cell embedded in supercooled mid-level stratus

    Directory of Open Access Journals (Sweden)

    J. Crosier

    2011-01-01

    Full Text Available Simultaneous observations of cloud microphysical properties were obtained by in-situ aircraft measurements and ground based Radar/Lidar. Widespread mid-level stratus cloud was present below a temperature inversion (~5 °C magnitude at 3.6 km altitude. Localised convection (peak updraft 1.5 m s−1 was observed 20 km west of the Radar station. This was associated with convergence at 2.5 km altitude. The convection was unable to penetrate the inversion capping the mid-level stratus.

    The mid-level stratus cloud was vertically thin (~400 m, horizontally extensive (covering 100 s of km and persisted for more than 24 h. The cloud consisted of supercooled water droplets and small concentrations of large (~1 mm stellar/plate like ice which slowly precipitated out. This ice was nucleated at temperatures greater than −12.2 °C and less than −10.0 °C, (cloud top and cloud base temperatures, respectively. No ice seeding from above the cloud layer was observed. This ice was formed by primary nucleation, either through the entrainment of efficient ice nuclei from above/below cloud, or by the slow stochastic activation of immersion freezing ice nuclei contained within the supercooled drops. Above cloud top significant concentrations of sub-micron aerosol were observed and consisted of a mixture of sulphate and carbonaceous material, a potential source of ice nuclei. Particle number concentrations (in the size range 0.1<D<3.0 μm were measured above and below cloud in concentrations of ~25 cm−3. Ice crystal concentrations in the cloud were constant at around 0.2 L−1. It is estimated that entrainment of aerosol particles into cloud cannot replenish the loss of ice nuclei from the cloud layer via precipitation.

    Precipitation from the mid-level stratus evaporated before reaching the surface, whereas rates of up to 1 mm h−1 were observed below the convective feature. There is strong

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

    Science.gov (United States)

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

    2014-06-01

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

  4. Involvement of water channel Aquaporin 5 in H2S-induced pulmonary edema.

    Science.gov (United States)

    Xu, Chunyang; Jiang, Lei; Zou, Yuxia; Xing, Jingjing; Sun, Hao; Zhu, Baoli; Zhang, Hengdong; Wang, Jun; Zhang, Jinsong

    2017-01-01

    Acute exposure to hydrogen sulfide (H2S) poses a significant threat to life, and the lung is one of the primary target organs of H2S. However, the mechanisms involved in H2S-induced acute pulmonary edema are poorly understood. This study aims to investigate the effects of H2S on the expression of water channel aquaporin 5 (AQP5) and to elucidate the signaling pathways involved in AQP5 regulation. In an in vivo study, C57BL6 mice were exposed to sub-lethal concentrations of inhaled H2S, and histological injury of the lungs and ultrastructure injury of the epithelial cells were evaluated. With real-time PCR and western blot assays, we found that H2S exposure contributed to a significant decrease in AQP5 expression both in murine lung tissue and the A549 cell line, and the ERK1/2 and p38 MAPK signaling pathways were demonstrated to be implicated in AQP5 regulation. Therefore, adjusting AQP5 protein levels could be considered a therapeutic strategy for the treatment of APE induced by H2S and other hazardous gases. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Water Channels Are Involved in Stomatal Oscillations Encoded by Parameter-Specific Cytosolic Calcium Oscillations

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Earlier studies have shown that various stimuli can induce specific cytosolic calcium ([Ca2+]cyt) oscillations in guard cells and various oscillations in stomatal apertures. Exactly how [Ca2+]cyt oscillation signaling functions in stomatal oscillation is not known. In the present study, the epidermis of broad bean (Vicia faba L.)was used and a rapid ion-exchange treatment with two shifting buffers differing in K+ and Ca2+ concentrations was applied. The treatment for five transients at a 10-min transient period induced clear and regular stomatal oscillation. However, for other transient numbers and periods, the treatments induced some irregular oscillations or even no obvious oscillations in stomatal aperture. The results indicate that stomatal oscillation is encoded by parameter-specific [Ca2+]cyt oscillation: the parameters of [Ca2+]cyt oscillation affected the occurrence rate and the parameters of stomatal oscillation. The water channel inhibitor HgCl2 completely inhibited stomatal oscillation and the inhibitory effect could be partially reversed by β-mercaptoethanol (an agent capable of reversing water channel inhibition by HgCl2). Other inhibitory treatments against ion transport (i.e. the application of LaCl3, EGTA, or tetraethylammonium chloride (TEACl))weakly impaired stomatal oscillation when the compounds were added after rapid ion-exchange treatment.If these compounds were added before rapid-ion exchange treatment, the inhibitory effect was much more apparent (except in the case of TEACI). The results of the present study suggest that water channels are involved in stomatal oscillation as a downstream element of [Ca2+]cyt oscillation signaling.

  6. A quantitative test of infrared optical constants for supercooled sulphuric and nitric acid droplet aerosols

    Directory of Open Access Journals (Sweden)

    R. Wagner

    2003-05-01

    Full Text Available In situ Fourier transform infrared (FTIR extinction spectra of supercooled H2SO4/H2O and HNO3/H2O solution droplets were recorded in the large coolable aerosol chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere of Forschungszentrum Karlsruhe for a range of aerosol compositions and at temperatures extending down to 192 K. The measured spectra were quantitatively analysed in terms of aerosol composition and mass concentration by using Mie theory in combination with published refractive index data as input parameters. Simultaneously, total sulphuric acid and nitric acid mass concentrations from filter analysis and total water concentrations measured with the Lyman-a hygrometer of Forschungszentrum Jülich were used to calculate the aerosol composition at thermodynamic equilibrium inside the aerosol chamber. By comparing these measured aerosol parameters with those retrieved from the analysis of the FTIR spectra, the accuracy of the literature data sets of refractive indices could be assessed. In summary, four data sets were tested in the H2SO4/H2O system as well as two data sets in the HNO3/H2O system, partly revealing significant discrepancies in the retrieved aerosol properties. Potential explanations for these differences are discussed in this paper.

  7. Measurements of electric charge separated during the formation of rime by the accretion of supercooled droplets

    Directory of Open Access Journals (Sweden)

    E. E. Avila

    2009-11-01

    Full Text Available In these experiments, the electric charge carried by single particles ejected from the surface of a graupel particle growing by riming was measured. Simulated graupel pellets were grown by accretion of supercooled water drops, at temperatures ranging from −2 to −10°C in a wind tunnel at air velocities between 5 and 10 m s−1, with the goal of studying the charging of graupel pellets under conditions of secondary ice crystal production (Hallett-Mossop mechanism. The graupel, and induction rings upstream and downstream of the graupel, were connected to electrometers and analyzing circuits of sufficient sensitivity and speed to measure, correlate and display individual charging events. The results suggest that fewer than 1% of the ejected particles carry a measurable electric charge (>2 fC. Further, it was observed that the graupel pellets acquire a positive charge and the average charge of a single splinter ejected is −14 fC. This mechanism of ejection of charged particles seems adequate to account for a positive charge of around 1 pC that individual precipitation particles of mm-size could acquire in the lower part of the cloud, which in turn could contribute to the lower positive charge region of thunderstorms.

  8. Spatiotemporal heterogeneity of local free volumes in highly supercooled liquid

    Science.gov (United States)

    Shiba, Hayato; Kawasaki, Takeshi

    2013-11-01

    We discuss the spatiotemporal behavior of local density and its relation to dynamical heterogeneity in a highly supercooled liquid by using molecular dynamics simulations of a binary mixture with different particle sizes in two dimensions. To trace voids heterogeneously existing with lower local densities, which move along with the structural relaxation, we employ the minimum local density for each particle in a time window whose width is set along with the structural relaxation time. Particles subject to free volumes correspond well to the configuration rearranging region of dynamical heterogeneity. While the correlation length for dynamical heterogeneity grows with temperature decrease, no growth in the correlation length of heterogeneity in the minimum local density distribution takes place. A comparison of these results with those of normal mode analysis reveals that superpositions of lower-frequency soft modes extending over the free volumes exhibit spatial correlation with the broken bonds. This observation suggests a possibility that long-ranged vibration modes facilitate the interactions between fragile regions represented by free volumes, to induce dynamical correlations at a large scale.

  9. The Transient Supercooling Enhancement For A Pulsed Thermoelectric Cooler (TEC)

    OpenAIRE

    Mao, Jia-ni; Du, Jun-yan; Wang, Shi-fei; Zhou, Jing-wei; Wang, Yu-Gang

    2016-01-01

    Once TEC excitated by a high-voltage pulse, there exists a transient thermoelectric supercooling effect, which can be enhanced by keeping on increasing the Peltier cooling effect to compensate for the negative self-heating from the Joule heating effect and Fourier heat conduction effect. After superimposing an additional voltage pulse over a steady-state reference value in a short time scale, abrupt temperature drop will be produc...

  10. Thermodynamic scaling of molecular dynamics in supercooled ibuprofen.

    Science.gov (United States)

    Adrjanowicz, K; Wojnarowska, Z; Paluch, M; Pionteck, J

    2011-04-28

    It was shown recently that ibuprofen revealed a strong tendency to form hydrogen bonded aggregates such as dimers and trimers of either cyclic or linear geometry, which somehow seems to control molecular mobility of that drug [Brás et al. J. Phys. Chem. B2008, 112 (35), 11 087-11 099]. For such hydrogen-bonded liquids, superpositioning of dynamics under various temperature T, pressure P, and volume V conditions, when plotted versus the scaling function of T(-1)V(-γ) (where γ is a material constant), may not always be satisfying. In the present work, we have tested the validity of this scaling for supercooled ibuprofen. In order to do that, pressure-volume-temperature (PVT) measurements combined with isobaric and isothermal dielectric relaxation studies (pressure up to 310 MPa) were carried out. The scaling properties of the examined drug were derived from the fitting of the τ(α)(T,V) dependences to the modified Avramov equation and by analyzing in double logarithmic scale the T(g)(V(g)) dependences, where the glass transition temperature T(g) and volume V(g) were defined for various relaxation times. In view of the obtained results, we conjecture that for ibuprofen the thermodynamic scaling idea works but not perfectly. The slight departure from the scaling behavior is discussed in the context of the hydrogen bonding abilities of the examined system and compared with the results reported for other strongly associated liquids.

  11. The Transient Supercooling Enhancement For A Pulsed Thermoelectric Cooler (TEC)

    OpenAIRE

    Mao, Jia-ni; Du, Jun-yan; Wang, Shi-fei; Zhou, Jing-wei; Wang, Yu-Gang

    2016-01-01

    Once TEC excitated by a high-voltage pulse, there exists a transient thermoelectric supercooling effect, which can be enhanced by keeping on increasing the Peltier cooling effect to compensate for the negative self-heating from the Joule heating effect and Fourier heat conduction effect. After superimposing an additional voltage pulse over a steady-state reference value in a short time scale, abrupt temperature drop will be produc...

  12. A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum.

    Science.gov (United States)

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

    2016-04-28

    A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond time scale in ultrahigh vacuum (UHV). Details of the design, implementation, and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ∼10(10) K/s for temperature increases of ∼100-200 K are obtained. Subsequent rapid cooling (∼5 × 10(9) K/s) quenches the film, permitting in-situ, post-heating analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ∼±2.7% leading to a temperature uncertainty of ∼±4.4 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces.

  13. A nanosecond pulsed laser heating system for studying liquid and supercooled liquid films in ultrahigh vacuum

    Science.gov (United States)

    Xu, Yuntao; Dibble, Collin J.; Petrik, Nikolay G.; Smith, R. Scott; Joly, Alan G.; Tonkyn, Russell G.; Kay, Bruce D.; Kimmel, Greg A.

    2016-04-01

    A pulsed laser heating system has been developed that enables investigations of the dynamics and kinetics of nanoscale liquid films and liquid/solid interfaces on the nanosecond time scale in ultrahigh vacuum (UHV). Details of the design, implementation, and characterization of a nanosecond pulsed laser system for transiently heating nanoscale films are described. Nanosecond pulses from a Nd:YAG laser are used to rapidly heat thin films of adsorbed water or other volatile materials on a clean, well-characterized Pt(111) crystal in UHV. Heating rates of ˜1010 K/s for temperature increases of ˜100-200 K are obtained. Subsequent rapid cooling (˜5 × 109 K/s) quenches the film, permitting in-situ, post-heating analysis using a variety of surface science techniques. Lateral variations in the laser pulse energy are ˜±2.7% leading to a temperature uncertainty of ˜±4.4 K for a temperature jump of 200 K. Initial experiments with the apparatus demonstrate that crystalline ice films initially held at 90 K can be rapidly transformed into liquid water films with T > 273 K. No discernable recrystallization occurs during the rapid cooling back to cryogenic temperatures. In contrast, amorphous solid water films heated below the melting point rapidly crystallize. The nanosecond pulsed laser heating system can prepare nanoscale liquid and supercooled liquid films that persist for nanoseconds per heat pulse in an UHV environment, enabling experimental studies of a wide range of phenomena in liquids and at liquid/solid interfaces.

  14. Effect of drop size on the impact thermodynamics for supercooled large droplet in aircraft icing

    Science.gov (United States)

    Zhang, Chen; Liu, Hong

    2016-06-01

    Supercooled large droplet (SLD), which can cause abnormal icing, is a well-known issue in aerospace engineering. Although efforts have been exerted to understand large droplet impact dynamics and the supercooled feature in the film/substrate interface, respectively, the thermodynamic effect during the SLD impact process has not received sufficient attention. This work conducts experimental studies to determine the effects of drop size on the thermodynamics for supercooled large droplet impingement. Through phenomenological reproduction, the rapid-freezing characteristics are observed in diameters of 400, 800, and 1300 μm. The experimental analysis provides information on the maximum spreading rate and the shrinkage rate of the drop, the supercooled diffusive rate, and the freezing time. A physical explanation of this unsteady heat transfer process is proposed theoretically, which indicates that the drop size is a critical factor influencing the supercooled heat exchange and effective heat transfer duration between the film/substrate interface. On the basis of the present experimental data and theoretical analysis, an impinging heating model is developed and applied to typical SLD cases. The model behaves as anticipated, which underlines the wide applicability to SLD icing problems in related fields.

  15. Liquid Supercoolability and Synthesis Kinetics of Quinary Refractory High-entropy Alloy

    Science.gov (United States)

    Wang, W. L.; Hu, L.; Yang, S. J.; Wang, A.; Wang, L.; Wei, B.

    2016-11-01

    The high-entropy configuration of equiatomic multicomponent alloys opens an effective access to the development of advanced materials. Here we report the synthesis of a new quinary refractory WMoTaNbZr high-entropy alloy under electrostatic levitation condition. It showed a high liquidus temperature of 2686 K and achieved a maximum supercooling of 640 K (0.24 TL) at molten state. The containerless measurements revealed a linear increasing tendency for both its liquid state density and the specific heat to emissivity ratio versus alloy supercooling. A high-entropy body-centered cubic (HEB) phase dominated its phase constitution despite the formation of a negligible amount of solid solution (Zr) phase. The dendritic growth of HEB phase always governed the crystallization process, attained a fastest growth velocity of 13.5 m/s and displayed a power function relation to alloy supercooling. The high speed videographic research of recalescence phenomenon indicated Johnson-Mehl-Avrami type transition kinetics for its rapid solidification process. As supercooling increases, the microstructures of primary HEB phase were refined conspicuously and exhibited an obvious solute trapping effect of the segregative Zr component. Meanwhile, the Vickers hardness of HEB phase displayed the rising tendency with supercooling.

  16. The Histaminergic Tuberomamillary Nucleus Is Involved in Appetite for Sex, Water and Amphetamine.

    Science.gov (United States)

    Contreras, Marco; Riveros, María E; Quispe, Maricel; Sánchez, Cristián; Perdomo, Guayec; Torrealba, Fernando; Valdés, José L

    2016-01-01

    The histaminergic system is one component of the ascending arousal system which is involved in wakefulness, neuroendocrine control, cognition, psychiatric disorders and motivation. During the appetitive phase of motivated behaviors the arousal state rises to an optimal level, thus giving proper intensity to the behavior. Previous studies have demonstrated that the histaminergic neurons show an earlier activation during the appetitive phase of feeding, compared to other ascending arousal system nuclei, paralleled with a high increase in arousal state. Lesions restricted to the histaminergic neurons in rats reduced their motivation to get food even after 24 h of food deprivation, compared with intact or sham lesioned rats. Taken together, these findings indicate that the histaminergic system is important for appetitive behavior related to feeding. However, its role in other goal-directed behaviors remains unexplored. In the present work, male rats rendered motivated to obtain water, sex, or amphetamine showed an increase in Fos-ir of histaminergic neurons in appetitive behaviors directed to get those reinforcers. However, during appetitive tests to obtain sex, or drug in amphetamine-conditioned rats, Fos expression increased in most other ascending arousal system nuclei, including the orexin neurons in the lateral hypothalamus, dorsal raphe, locus coeruleus and laterodorsal tegmental neurons, but not in the ventral tegmental area, which showed no Fos-ir increase in any of the 3 conditions. Importantly, all these appetitive behaviors were drastically reduced after histaminergic cell-specific lesion, suggesting a critical contribution of histamine on the intensity component of several appetitive behaviors.

  17. Water-soluble chlorophyll protein is involved in herbivore resistance activation during greening of Arabidopsis thaliana

    Science.gov (United States)

    Boex-Fontvieille, Edouard; Rustgi, Sachin; von Wettstein, Diter; Reinbothe, Steffen; Reinbothe, Christiane

    2015-01-01

    Water-soluble chlorophyll proteins (WSCPs) constitute a small family of unusual chlorophyll (Chl)-binding proteins that possess a Kunitz-type protease inhibitor domain. In Arabidopsis thaliana, a WSCP has been identified, named AtWSCP, that forms complexes with Chl and the Chl precursor chlorophyllide (Chlide) in vitro. AtWSCP exhibits a quite unexpected expression pattern for a Chl binding protein and accumulated to high levels in the apical hook of etiolated plants. AtWSCP expression was negatively light-regulated. Transgenic expression of AtWSCP fused to green fluorescent protein (GFP) revealed that AtWSCP is localized to cell walls/apoplastic spaces. Biochemical assays identified AtWSCP as interacting with RD21 (RESPONSIVE TO DESICCATION 21), a granulin domain-containing cysteine protease implicated in stress responses and defense. Reconstitution experiments showed tight interactions between RD21 and WSCP that were relieved upon Chlide binding. Laboratory feeding experiments with two herbivorous isopod crustaceans, Porcellio scaber (woodlouse) and Armadillidium vulgare (pillbug), identified the apical hook as Achilles’ heel of etiolated plants and that this was protected by RD21 during greening. Because Chlide is formed in the apical hook during seedling emergence from the soil, our data suggest an unprecedented mechanism of herbivore resistance activation that is triggered by light and involves AtWSCP. PMID:26016527

  18. Droplet-Sizing Liquid Water Content Sensor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Icing is one of the most significant hazards to aircraft. A sizing supercooled liquid water content (SSLWC) sonde is being developed to meet a directly related need...

  19. [The global and national context regarding the challenges involved in ensuring adequate access to water for human consumption].

    Science.gov (United States)

    Augusto, Lia Giraldo da Silva; Gurgel, Idê Gomes Dantas; Câmara Neto, Henrique Fernandes; de Melo, Carlos Henrique; Costa, André Monteiro

    2012-06-01

    The scope of this article is to analyze the challenges involved in ensuring access to water for human consumption taking the international and national context into consideration. Based on the UN declaration that access to safe and clean drinking water is a fundamental human right, vulnerabilities are identified that can consist in restrictions to access to adequate supplies. The distribution of water and the population across the planet, pollution, inadequate policies and management lead to environmental injustice. The iniquity of access to water constitutes the contemporary water crisis. From the 1980s onwards, the transnational water market emerged for private control that occurs at three main levels: surface and underground water sources; bottled water; and public water supply services. The conflicts of the multiple uses of water resources, the market and environmental problems have contributed to rendering the health of the population and ecosystems vulnerable. Adequate public policies are essential to ensure the basic human right to access to safe and clean drinking water.

  20. An investigation on supercooling directional solidification process of Cu-Ni single phase alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Supercooling directional solidification (SDS) is put forward by combination of melt supercooling and conventional solidification by application of supercooling inheritance. On the self-designed SDS equipment, SDS of Cu-Ni alloy was achieved successfully. The results are as follows: (ⅰ) The primary arm spacing is about 30 m m, the growth of secondary arms are strongly suppressed. The primary arm spacing is nearly the same as LMC method (GL=25 K/mm, V=500 m m/s), the primary stems are straight, fine and completed, with an inclination angle of about 5.8o. (ⅱ) A semi-quantitative T-T model is brought forward to describe the dendrite growth rate V vs. undercooling D T. The prediction of T-T model agrees well with experimental results. The formation of fine equiaxed dendrites, transition region and dendrite region can be explained successfully by D T-V-x relation of T-T model.

  1. The Histaminergic Tuberomamillary Nucleus Is Involved in Appetite for Sex, Water and Amphetamine.

    Directory of Open Access Journals (Sweden)

    Marco Contreras

    Full Text Available The histaminergic system is one component of the ascending arousal system which is involved in wakefulness, neuroendocrine control, cognition, psychiatric disorders and motivation. During the appetitive phase of motivated behaviors the arousal state rises to an optimal level, thus giving proper intensity to the behavior. Previous studies have demonstrated that the histaminergic neurons show an earlier activation during the appetitive phase of feeding, compared to other ascending arousal system nuclei, paralleled with a high increase in arousal state. Lesions restricted to the histaminergic neurons in rats reduced their motivation to get food even after 24 h of food deprivation, compared with intact or sham lesioned rats. Taken together, these findings indicate that the histaminergic system is important for appetitive behavior related to feeding. However, its role in other goal-directed behaviors remains unexplored. In the present work, male rats rendered motivated to obtain water, sex, or amphetamine showed an increase in Fos-ir of histaminergic neurons in appetitive behaviors directed to get those reinforcers. However, during appetitive tests to obtain sex, or drug in amphetamine-conditioned rats, Fos expression increased in most other ascending arousal system nuclei, including the orexin neurons in the lateral hypothalamus, dorsal raphe, locus coeruleus and laterodorsal tegmental neurons, but not in the ventral tegmental area, which showed no Fos-ir increase in any of the 3 conditions. Importantly, all these appetitive behaviors were drastically reduced after histaminergic cell-specific lesion, suggesting a critical contribution of histamine on the intensity component of several appetitive behaviors.

  2. Long term thermal energy storage with stable supercooled sodium acetate trihydrate

    DEFF Research Database (Denmark)

    Dannemand, Mark; Schultz, Jørgen M.; Johansen, Jakob Berg

    2015-01-01

    Utilizing stable supercooling of sodium acetate trihydrate makes it possible to store thermal energy partly loss free. This principle makes seasonal heat storage in compact systems possible. To keep high and stable energy content and cycling stability phase separation of the storage material must...... to 230 kJ/kg. TRNSYS simulations of a solar combi system including a storage with four heat storage modules of each 200 kg of sodium acetate trihydrate utilizing stable supercooling achieved a solar fraction of 80% for a low energy house in Danish climatic conditions....

  3. Removal of the microorganisms from water. Part 1: Introduction, water-borne disease and the microorganisms involved.

    CSIR Research Space (South Africa)

    Duuren, FR

    1967-01-01

    Full Text Available in the spread (this) disease. Forward strides taken since, in sanitation and water ply practice, have all but eliminated the incidence of ~h major water-borne diseases as cholera and typhoid er in the western world. The improvements which ye been effected... colonies, demonstrated in his investigation of the Calcutta water supplies, the presence of Vibrio comma which caused the cholera epidemic 2 It is apparent from modern reporting that the con siderations applied in deciding on whether or not a disease...

  4. Conclusions from Ufa, Russia, drinking water dioxin cleanup experiments involving different treatment technologies.

    Science.gov (United States)

    Smirnov, A D; Schecter, A; Papke, O; Beljak, A A

    1996-02-01

    The city of Ufa, in the Bashkortostan Republic of Russia, is believed to have dioxin contamination of its water supply from 30 years of gas ejections, sewage and buried sludge from the Chimprom industrial factory, and possibly other sources. A project was developed to provide technology at relatively low cost for treating dioxin contaminated water in routine and also in emergency situations. This paper describes the results of the 15-year research project to remove dioxins from drinking water. Three different methods were experimentally tested for efficiency at removing dioxins from tap water. The methods used were: (1) ozonization plus filtration through powder sorbents, (2) filtration through sand, and (3) filtration through granulated sorbents. It was found that the method of filtration through granulated sorbents was most effective at removing dioxins from water: 90-95% of all PCDD and PCDF isomers were removed from water samples. This research also shows that the most toxic congener, 2,3,7,8-TCDD, can be removed effectively and efficiently. In addition, there are no significant differences between the extractability of PCDDs and PCDFs. Reductions in exposure to humans from contaminated drinking water can be accomplished via sorptive water treatments for relatively reasonable cost, making this a practical approach. This method of decreasing toxic chemicals is being implemented in Ufa, Russia.

  5. An integrated process analytical technology (PAT) approach to monitoring the effect of supercooling on lyophilization product and process parameters of model monoclonal antibody formulations.

    Science.gov (United States)

    Awotwe Otoo, David; Agarabi, Cyrus; Khan, Mansoor A

    2014-07-01

    The aim of the present study was to apply an integrated process analytical technology (PAT) approach to control and monitor the effect of the degree of supercooling on critical process and product parameters of a lyophilization cycle. Two concentrations of a mAb formulation were used as models for lyophilization. ControLyo™ technology was applied to control the onset of ice nucleation, whereas tunable diode laser absorption spectroscopy (TDLAS) was utilized as a noninvasive tool for the inline monitoring of the water vapor concentration and vapor flow velocity in the spool during primary drying. The instantaneous measurements were then used to determine the effect of the degree of supercooling on critical process and product parameters. Controlled nucleation resulted in uniform nucleation at lower degrees of supercooling for both formulations, higher sublimation rates, lower mass transfer resistance, lower product temperatures at the sublimation interface, and shorter primary drying times compared with the conventional shelf-ramped freezing. Controlled nucleation also resulted in lyophilized cakes with more elegant and porous structure with no visible collapse or shrinkage, lower specific surface area, and shorter reconstitution times compared with the uncontrolled nucleation. Uncontrolled nucleation however resulted in lyophilized cakes with relatively lower residual moisture contents compared with controlled nucleation. TDLAS proved to be an efficient tool to determine the endpoint of primary drying. There was good agreement between data obtained from TDLAS-based measurements and SMART™ technology. ControLyo™ technology and TDLAS showed great potential as PAT tools to achieve enhanced process monitoring and control during lyophilization cycles. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  6. Crystallization in diblock copolymer thin films at different degrees of supercooling

    DEFF Research Database (Denmark)

    Darko, C.; Botiz, I.; Reiter, G.

    2009-01-01

    The crystalline structures in thin films of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) diblock copolymers were studied in dependence on the degree of supercooling. Atomic force microscopy showed that the crystalline domains (lamellae) consist of grains, which are macroscopic at low...

  7. Supercooling Suppression of Microencapsulated n-Alkanes by Introducing an Organic Gelator

    Institute of Scientific and Technical Information of China (English)

    ZHU Kong-ying; WANG Shuang; QI Heng-zhi; LI Hui; ZHAO Yun-hui; YUAN Xiao-yan

    2012-01-01

    Supercooling of the microencapsulated phase change materials(PCMs) during cooling usually happens.This phenomenon can interfere with heat transfer and is necessary to further overcome.In this study,melamine-formaldehyde microcapsules containing two n-alkane PCMs,namely,n-dodecane(C12) or n-tetradecane(C14)were prepared by in situ polymerization.A small amount of n-hexatriacontane(C36) was introduced as an organic gelator into the core of microcapsules to cope with the supercooling problem.Analyses demonstrate that supcrcooling of the microencapsulated C12 or C14 was significantly suppressed by adding 3%(mass fraction) C36,without changing the spherical morphology and dispersibility.It could be also found that the enthalpy of microencapsulated C12 or C14 containing C36 was similar to that of microencapsulated n-alkanes without C36,whereas the difference between onsets of crystallization and melting(degree of supercooling) is similar to that of those of pure n-alkanes,suggesting the remarkable suppression ability of the organic gelator on supercooling.

  8. Compressive Deformation Induced Nanocrystallization of a Supercooled Zr-Based Bulk Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-Lin; SHAN De-Bin; MA Ming-Zhen; GUO Bin

    2008-01-01

    The nanocrystallization behaviour of a bulk Zr-based metallic glass subjected to compressive stress is investigated in the supercooled liquid region. Compared with annealing treatments without compressive stress, compressive deformation promotes the development of nucleation and suppresses the coarsening of nanocrystallites at high ternperatures.

  9. Predicting How Nanoconfinement Changes the Relaxation Time of a Supercooled Liquid

    DEFF Research Database (Denmark)

    Ingebrigtsen, Trond; Errington, Jeff; Truskett, Tom;

    2013-01-01

    asymmetric dumbbell-shaped molecules, which can be deeply supercooled without crystallizing. We find that the dimensionless structural relaxation times—spanning six decades as a function of temperature, density, and degree of confinement—collapse when plotted versus excess entropy. The data also collapse...

  10. Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

    DEFF Research Database (Denmark)

    Jakobsen, Bo; Sanz, Alejandro; Niss, Kristine;

    2016-01-01

    We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat...

  11. Lipid Oxidation in Oil‐in‐Water Emulsions: Involvement of the Interfacial Layer

    National Research Council Canada - National Science Library

    Berton‐Carabin, Claire C; Ropers, Marie‐Hélène; Genot, Claude

    2014-01-01

    .... This review establishes the state‐of‐the‐art on lipid oxidation in oil‐in‐water (O/W) emulsions, with an emphasis on the role of the interfacial region, a critical area in the system in that respect...

  12. SMALL-SCALED WATER RESOURCES PROJECT IN THAILAND: FAILURE ANALYSIS AND IMPROVEMENT OF STAKEHOLDER INVOLVEMENT

    OpenAIRE

    URAIWONG, Piriya; WATANABE, Tsunemi

    2012-01-01

    Since its rapid economic development in the past thirty years, Thailand has implemented a number of water resources infrastructures significantly to support rapid rural development, industrialization, tourism development, domestic consumption, agriculture and other demands. However, many small-scale water resource projects gave rise to undesirable long-term fiscal burdens on the national government. This malfunction of existing facilities due to poor maintenance is typical case of collective ...

  13. Short communication: The water footprint of dairy products: case study involving skim milk powder.

    Science.gov (United States)

    Ridoutt, B G; Williams, S R O; Baud, S; Fraval, S; Marks, N

    2010-11-01

    In the context of global water scarcity and food security concerns, water footprints are emerging as an important sustainability indicator in the agriculture and food sectors. Using a recently developed life cycle assessment-based methodology that takes into account local water stress where operations occur, the normalized water footprints of milk products from South Gippsland, one of Australia's major dairy regions, were 14.4 L/kg of total milk solids in whole milk (at farm gate) and 15.8 L/kg of total milk solids in skim milk powder (delivered to export destination). These results demonstrate that dairy products can be produced with minimal potential to contribute to freshwater scarcity. However, not all dairy production systems are alike and the variability in water footprints between systems and products should be explored to obtain strategic insights that will enable the dairy sector to minimize its burden on freshwater systems from consumptive water use. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  14. Involvement of Protein Phosphorylation in Water Stress-induced Antioxidant Defense in Maize Leaves

    Institute of Scientific and Technical Information of China (English)

    Shu-cheng Xu; Hai-dong Ding; Feng-xia Su; A-ying Zhang; Ming-yi Jiang

    2009-01-01

    Using pharmacological and biochemical approaches, the role of protein phosphorylation and the interrelationship between water stress-enhanced kinase activity, antioxidant enzyme activity, hydrogen peroxide (H2O2) accumulation and endogenous abscisic acid in maize (Zea mays L.) leaves were investigated. Water-stress upregulated the activities of total protein phosphorylation and Ca2+ -dependent protein kinase, and the upregulation was blocked in abscisic acid-deficient vp5 mutant. Furthermore, pretreatments with a nicotinamide adenine dinucleotide phosphate oxidase inhibitor and a scavenger of H2O2 significantly reduced the increased activities of total protein kinase and Ca2+-dependent protein kinase in maize leaves exposed to water stress. Pretreatments with different protein kinase inhibitors also reduced the water stress-induced H2O2 production and the water stress-enhanced activities of antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase. The data suggest that protein phosphorylation and H2O2 generation are required for water stress-induced antioxidant defense in maize leaves and that crosstalk between protein phosphorylation and H2O2 generation may occur.

  15. Nitric Oxide Reduces Hydrogen Peroxide Accumulation Involved in Water Stress-induced Subcellular Anti-oxidant Defense in Maize Plants

    Institute of Scientific and Technical Information of China (English)

    Jianrong Sang; Mingyi Jiang; Fan Lin; Shucheng Xu; Aying Zhang; Mingpu Tan

    2008-01-01

    Nitric oxide (NO) Is a bioactive molecule involved in many biological events, and has been reported as pro-oxidant as well as anti-oxidant in plants. In the present study, the sources of NO production under water stress, the role of NO in water stress-induced hydrogen peroxide (H2O2) accumulation and subcellular activities of anti-oxidant enzymes in leaves of maize (Zea mays L.) plants were investigated. Water stress Induced defense increases in the generation of NO In maize mesphyll cells and the activity of nitric oxide synthase (NOS) in the cytosolic and microsomal fractions of maize leaves. Water stress-induced defense increases in the production of NO were blocked by pretreatments with Inhibitors of NOS and nitrate reductase (NR), suggesting that NO is produced from NOS and NR in leaves of maize plants exposed to water stress. Water stress also induced increases in the activities of the chloroplastic and cytosolic anti-oxidant enzymes superoxide dismutase (SOD), ascorbate peroxidass (APX), and glutathione reductase (GR), and the increases in the activities of anti-oxidant enzymes were reduced by pretreatments with inhibitors of NOS and NR. Exogenous NO increases the activities of water stress-induced subcellular anti-oxidant enzymes, which decreases accumulation of H2O2. Our results suggest that NOS and NR are involved in water strese-induced NO production and NOS is the major source of NO. The potential ability of NO to scavenge H2O2 is, at least in part, due to the induction of a subcellular anti-oxidant defense.

  16. Influence of Nanoparticles and Graphite Foam on the Supercooling of Acetamide

    Directory of Open Access Journals (Sweden)

    Jia Yu

    2014-01-01

    Full Text Available Acetamide is a promising phase change materials (PCMs for thermal storage,but the large supercooling during the freezing process has limited its application. In this study, we prepared acetamide-SiO2 composites by adding nano-SiO2 into acetamide. This modified PCM was then impregnated into the porous graphite foam forming acetamide-SiO2-graphite foam form-stable composites. These composites were subjected to melting-solidification cycles 50 times; the time-temperature curves were tracked and recorded during these cycles. The time-temperature curves showed that, for the acetamide containing 2 wt. % SiO2, the supercooling phenomenon was eliminated and the material’s performance was stable for 50 cycles. The solidification temperature of the acetamide-SiO2-graphite foam samples was 65°C and the melting temperature was lowered to 65°C. The samples exhibited almost no supercooling and the presence of SiO2 had no significant effect on the melting-solidification temperature. The microscopic supercooling of the acetamide-SiO2 composite was measured using differential scanning calorimetry (DSC. The results indicated that when the content of SiO2 was 1 wt. to 2 wt. %, the supercooling could be reduced to less than 10°C and heat was sufficiently released during solidification. Finally, a set of algorithms was derived using MATLAB software for simulating the crystallization of samples based on the classical nucleation theory. The results of the simulation agreed with the experiment results.

  17. Mechanical responses and stress fluctuations of a supercooled liquid in a sheared non-equilibrium state.

    Science.gov (United States)

    Mizuno, H; Yamamoto, R

    2012-04-01

    A steady shear flow can drive supercooled liquids into a non-equilibrium state. Using molecular dynamics simulations under steady shear flow superimposed with oscillatory shear strain for a probe, non-equilibrium mechanical responses are studied for a model supercooled liquid composed of binary soft spheres. We found that even in the strongly sheared situation, the supercooled liquid exhibits surprisingly isotropic responses to oscillating shear strains applied in three different components of the strain tensor. Based on this isotropic feature, we successfully constructed a simple two-mode Maxwell model that can capture the key features of the storage and loss moduli, even for highly non-equilibrium state. Furthermore, we examined the correlation functions of the shear stress fluctuations, which also exhibit isotropic relaxation behaviors in the sheared non-equilibrium situation. In contrast to the isotropic features, the supercooled liquid additionally demonstrates anisotropies in both its responses and its correlations to the shear stress fluctuations. Using the constitutive equation (a two-mode Maxwell model), we demonstrated that the anisotropic responses are caused by the coupling between the oscillating strain and the driving shear flow. Due to these anisotropic responses and fluctuations, the violation of the fluctuation-dissipation theorem (FDT) is distinct for different components. We measured the magnitude of this violation in terms of the effective temperature. It was demonstrated that the effective temperature is notably different between different components, which indicates that a simple scalar mapping, such as the concept of an effective temperature, oversimplifies the true nature of supercooled liquids under shear flow. An understanding of the mechanism of isotropies and anisotropies in the responses and fluctuations will lead to a better appreciation of these violations of the FDT, as well as certain consequent modifications to the concept of an

  18. Breaking Through the Glass Ceiling: Recent Experimental Approaches to Probe the Properties of Supercooled Liquids near the Glass Transition.

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. Scott; Kay, Bruce D.

    2012-03-15

    Experimental measurements of the properties supercooled liquids at temperatures near their respective glass transition temperatures, Tg, are requisite for understanding the behavior of glasses and amorphous solids. Unfortunately, many supercooled molecular liquids rapidly crystallize at temperatures far above their Tg making such measurements difficult to nearly impossible. In this perspective we discuss some recent alternative approaches to obtain experimental data in the temperature regime near Tg. These new approaches may yield the additional experimental data necessary to test current theoretical models of the dynamical slowdown that occurs in supercooled liquids approaching the glass transition.

  19. Breaking Through the Glass Ceiling: Recent Experimental Approaches to Probe the Properties of Supercooled Liquids near the Glass Transition.

    Science.gov (United States)

    Smith, R Scott; Kay, Bruce D

    2012-03-15

    Experimental measurements of the properties of supercooled liquids at temperatures near their glass transition temperatures, Tg, are requisite for understanding the behavior of glasses and amorphous solids. Unfortunately, many supercooled molecular liquids rapidly crystallize at temperatures far above their Tg, making such measurements difficult to nearly impossible. In this Perspective, we discuss some recent alternative approaches to obtain experimental data in the temperature regime near Tg. These new approaches may yield the additional experimental data necessary to test current theoretical models of the dynamical slowdown that occurs in supercooled liquids approaching the glass transition.

  20. MzPIP2;1: An Aquaporin Involved in Radial Water Movement in Both Water Uptake and Transportation, Altered the Drought and Salt Tolerance of Transgenic Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Lin Wang

    Full Text Available Plants are unavoidably subjected to various abiotic stressors, including high salinity, drought and low temperature, which results in water deficit and even death. Water uptake and transportation play a critical role in response to these stresses. Many aquaporin proteins, localized at different tissues, function in various transmembrane water movements. We targeted at the key aquaporin in charge of both water uptake in roots and radial water transportation from vascular tissues through the whole plant.The MzPIP2;1 gene encoding a plasma membrane intrinsic protein was cloned from salt-tolerant apple rootstock Malus zumi Mats. The GUS gene was driven by MzPIP2;1 promoter in transgenic Arabidopsis. It indicated that MzPIP2;1 might function in the epidermal and vascular cells of roots, parenchyma cells around vessels through the stems and vascular tissues of leaves. The ectopically expressed MzPIP2;1 conferred the transgenic Arabidopsis plants enhanced tolerance to slight salt and drought stresses, but sensitive to moderate salt stress, which was indicated by root length, lateral root number, fresh weight and K+/Na+ ratio. In addition, the possible key cis-elements in response to salt, drought and cold stresses were isolated by the promoter deletion experiment.The MzPIP2;1 protein, as a PIP2 aquaporins subgroup member, involved in radial water movement, controls water absorption and usage efficiency and alters transgenic plants drought and salt tolerance.

  1. Public Involvement Techniques: A Reader of Ten Years Experience at the Institute for Water Resource

    Science.gov (United States)

    1983-05-01

    August 1967. 32. Gary D. Lynn, Emory N. Castle, C. Gibbs , Alternative Evaluation Procedures and Water Development Projects, The Multiple Objective...Corps help write the genera l paroft cond~toe itios Act instht thetCar" generlpd• to Its regla ~ltory alctivities and provide Input Itot hcw the &*natal

  2. Protein phosphorylation is involved in the water stress induced ABA accumulation in the roots of Malus hupehensis Rehd

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Water stress-induced ABA accumulation plays a key role in the root to shoot communication and/or the cell to cell signaling under the soil stresses. The signaling of the water stress itself that leads to the accumulation, however, is less known. In this study, we subjected the roots of Malus hupehensis seedlings to water stress treatment and investigated the ABA accumulation in relation to protein phosphorylation. Our results showed that ABA accumulation could be substantially triggered in 40 min and reached 4 folds in 100 min after treatment with 30% PEG 6000 (polyethylene glycol). The water stress treatment also led to a substantial enhancement of total kinase activity, assessed with histone-Ⅲ as substrate, in 15 min and a maximum enhancement in 30 min before it declined to initial level. The Ca2+-dependent kinase activity showed a similar, if not more sensitive, trend. When the roots were fed with labeled 32pATP, water stress enhanced the labeling of proteins, which showed a maximum labeling at 40 min. Two inhibitors of protein kinases, Quercetin and H7, effectively diminished or completely blocked the ABA accumulation under the stress treatment. It is therefore suggest that protein phosphorylation is involved in the signaling of the water stress-induced ABA accumulation.

  3. Removal of sulfamethoxazole and diclofenac from water: strategies involving O3 and H2O2.

    Science.gov (United States)

    Gomes, Daniela S; Gando-Ferreira, Licínio M; Quinta-Ferreira, Rosa M; Martins, Rui C

    2017-06-08

    Diclofenac (DCF) and Sulfamethoxazole (SMX) are two of the most frequently detected pharmaceutical compounds in water and are hardly removed by biological treatment systems. The presence of H2O2 was investigated in the ozonation of these two compounds. Experiments were carried out with both using distilled water and secondary effluent from a municipal wastewater treatment plant spiked with pharmaceuticals. Chemical oxygen demand (COD) abatement rate improved when H2O2 was added at the beginning of the ozonation process and when the ozone inlet concentration increased, attaining a maximum value of 91% and simultaneously a lower ozone waste for a H2O2 initial concentration of 5 mM and an ozone inlet concentration of 20 g Nm(-3). For these operation conditions, the water matrix has no significant impact on SMX and DCF removal, which were totally degraded in 45 and 60 min, respectively. Nevertheless, lower COD degradation and ozone usage were obtained when the secondary effluent was used. Inorganic ions such as chloride, sulphate and nitrate and short-chain organic compounds were detected as by-products of the SMX and DCF oxidation. Vibrio fischeri luminescence inhibition tests revealed that simultaneous use of ozone and H2O2 reduced acute toxicity.

  4. ESKIMO1 is a key gene involved in water economy as well as cold acclimation and salt tolerance

    Directory of Open Access Journals (Sweden)

    Yu Agnes

    2008-12-01

    Full Text Available Abstract Background Drought is a major social and economic problem resulting in huge yield reduction in the field. Today's challenge is to develop plants with reduced water requirements and stable yields in fluctuating environmental conditions. Arabidopsis thaliana is an excellent model for identifying potential targets for plant breeding. Drought tolerance in the field was successfully conferred to crops by transferring genes from this model species. While involved in a plant genomics programme, which aims to identify new genes responsible for plant response to abiotic stress, we identified ESKIMO1 as a key gene involved in plant water economy as well as cold acclimation and salt tolerance. Results All esk1 mutants were more tolerant to freezing, after acclimation, than their wild type counterpart. esk1 mutants also showed increased tolerance to mild water deficit for all traits measured. The mutant's improved tolerance to reduced water supply may be explained by its lower transpiration rate and better water use efficiency (WUE, which was assessed by carbon isotope discrimination and gas exchange measurements. esk1 alleles were also shown to be more tolerant to salt stress. Transcriptomic analysis of one mutant line and its wild-type background was carried out. Under control watering conditions a number of genes were differentially expressed between the mutant and the wild type whereas under mild drought stress this list of genes was reduced. Among the genes that were differentially expressed between the wild type and mutant, two functional categories related to the response to stress or biotic and abiotic stimulus were over-represented. Under salt stress conditions, all gene functional categories were represented equally in both the mutant and wild type. Based on this transcriptome analysis we hypothesise that in control conditions the esk1 mutant behaves as if it was exposed to drought stress. Conclusion Overall our findings suggest that the

  5. Arabidopsis ECERIFERUM9 involvement in cuticle formation and maintenance of plant water status

    KAUST Repository

    Lu, Shiyou

    2012-05-25

    Mutation of the ECERIFERUM9 (CER9) gene in Arabidopsis (Arabidopsis thaliana) causes elevated amounts of 18-carbon-length cutin monomers and a dramatic shift in the cuticular wax profile (especially on leaves) toward the very-long-chain free fatty acids tetracosanoic acid (C24) and hexacosanoic acid (C26). Relative to the wild type, cer9 mutants exhibit elevated cuticle membrane thickness over epidermal cells and cuticular ledges with increased occlusion of the stomatal pore. The cuticular phenotypes of cer9 are associated with delayed onset of wilting in plants experiencing water deficit, lower transpiration rates, and improved water use efficiency measured as carbon isotope discrimination. The CER9 protein thus encodes a novel determinant of plant drought tolerance-associated traits, one whose deficiency elevates cutin synthesis, redistributes wax composition, and suppresses transpiration. Map-based cloning identified CER9, and sequence analysis predicted that it encodes an E3 ubiquitin ligase homologous to yeast Doa10 (previously shown to target endoplasmic reticulum proteins for proteasomal degradation). To further elucidate CER9 function, the impact of CER9 deficiency on interactions with other genes was examined using double mutant and transcriptome analyses. For both wax and cutin, cer9 showed mostly additive effects with cer6, long-chain acyl-CoA synthetase1 (lacs1), and lacs2 and revealed its role in early steps of both wax and cutin synthetic pathways. Transcriptome analysis revealed that the cer9 mutation affected diverse cellular processes, with primary impact on genes associated with diverse stress responses. The discovery of CER9 lays new groundwork for developing novel cuticle-based strategies for improving the drought tolerance and water use efficiency of crop plants. © 2012 American Society of Plant Biologists. All Rights Reserved.

  6. Arabidopsis ECERIFERUM9 involvement in cuticle formation and maintenance of plant water status.

    Science.gov (United States)

    Lü, Shiyou; Zhao, Huayan; Des Marais, David L; Parsons, Eugene P; Wen, Xiaoxue; Xu, Xiaojing; Bangarusamy, Dhinoth K; Wang, Guangchao; Rowland, Owen; Juenger, Thomas; Bressan, Ray A; Jenks, Matthew A

    2012-07-01

    Mutation of the ECERIFERUM9 (CER9) gene in Arabidopsis (Arabidopsis thaliana) causes elevated amounts of 18-carbon-length cutin monomers and a dramatic shift in the cuticular wax profile (especially on leaves) toward the very-long-chain free fatty acids tetracosanoic acid (C₂₄) and hexacosanoic acid (C₂₆). Relative to the wild type, cer9 mutants exhibit elevated cuticle membrane thickness over epidermal cells and cuticular ledges with increased occlusion of the stomatal pore. The cuticular phenotypes of cer9 are associated with delayed onset of wilting in plants experiencing water deficit, lower transpiration rates, and improved water use efficiency measured as carbon isotope discrimination. The CER9 protein thus encodes a novel determinant of plant drought tolerance-associated traits, one whose deficiency elevates cutin synthesis, redistributes wax composition, and suppresses transpiration. Map-based cloning identified CER9, and sequence analysis predicted that it encodes an E3 ubiquitin ligase homologous to yeast Doa10 (previously shown to target endoplasmic reticulum proteins for proteasomal degradation). To further elucidate CER9 function, the impact of CER9 deficiency on interactions with other genes was examined using double mutant and transcriptome analyses. For both wax and cutin, cer9 showed mostly additive effects with cer6, long-chain acyl-CoA synthetase1 (lacs1), and lacs2 and revealed its role in early steps of both wax and cutin synthetic pathways. Transcriptome analysis revealed that the cer9 mutation affected diverse cellular processes, with primary impact on genes associated with diverse stress responses. The discovery of CER9 lays new groundwork for developing novel cuticle-based strategies for improving the drought tolerance and water use efficiency of crop plants.

  7. Involvement of Cytokines in the Pathogenesis of Salt and Water Imbalance in Congestive Heart Failure

    Directory of Open Access Journals (Sweden)

    Zaher S. Azzam

    2017-06-01

    Full Text Available Congestive heart failure (CHF has become a major medical problem in the western world with high morbidity and mortality rates. CHF adversely affects several systems, mainly the kidneys and the lungs. While the involvement of the renin–angiotensin–aldosterone system and the sympathetic nervous system in the progression of cardiovascular, pulmonary, and renal dysfunction in experimental and clinical CHF is well established, the importance of pro-inflammatory mediators in the pathogenesis of this clinical setting is still evolving. In this context, CHF is associated with overexpression of pro-inflammatory cytokines, such as tumor necrosis factor-α, interleukin (IL-1, and IL-6, which are activated in response to environmental injury. This family of cytokines has been implicated in the deterioration of CHF, where it plays an important role in initiating and integrating homeostatic responses both at the myocardium and circulatory levels. We and others showed that angiotensin II decreased the ability of the lungs to clear edema and enhanced the fibrosis process via phosphorylation of the mitogen-activated protein kinases p38 and p42/44, which are generally involved in cellular responses to pro-inflammatory cytokines. Literature data also indicate the involvement of these effectors in modulating ion channel activity. It has been reported that in heart failure due to mitral stenosis; there were varying degrees of vascular and other associated parenchymal changes such as edema and fibrosis. In this review, we will discuss the effects of cytokines and other inflammatory mediators on the kidneys and the lungs in heart failure; especially their role in renal and alveolar ion channels activity and fluid balance.

  8. Thermalization calorimetry: A simple method for investigating glass transition and crystallization of supercooled liquids

    Directory of Open Access Journals (Sweden)

    Bo Jakobsen

    2016-05-01

    Full Text Available We present a simple method for fast and cheap thermal analysis on supercooled glass-forming liquids. This “Thermalization Calorimetry” technique is based on monitoring the temperature and its rate of change during heating or cooling of a sample for which the thermal power input comes from heat conduction through an insulating material, i.e., is proportional to the temperature difference between sample and surroundings. The monitored signal reflects the sample’s specific heat and is sensitive to exo- and endothermic processes. The technique is useful for studying supercooled liquids and their crystallization, e.g., for locating the glass transition and melting point(s, as well as for investigating the stability against crystallization and estimating the relative change in specific heat between the solid and liquid phases at the glass transition.

  9. Supercooling transition in phase separated manganite thin films: An electrical transport study

    Science.gov (United States)

    Singh, Sandeep; Kumar, Pawan; Siwach, P. K.; Tyagi, Pawan Kumar; Singh, H. K.

    2014-05-01

    The impact of variation in the relative fractions of the ferromagnetic metallic and antiferromagnetic/charge ordered insulator phases on the supercooling/superheating transition in strongly phase separated system, La5/8-yPryCa3/8MnO3 (y ≈ 0.4), has been studied employing magnetotransport measurements. Our study clearly shows that the supercooling transition temperature is non-unique and strongly depends on the magneto-thermodynamic path through which the low temperature state is accessed. In contrast, the superheating transition temperature remains constant. The thermo-magnetic hysteresis, the separation of the two transitions and the associated resistivity, all are functions of the relative fraction of the coexisting phases.

  10. Metastable Demixing of Supercooled Cu-Co and Cu-Fe Alloys in an Oxide Flux

    Science.gov (United States)

    Li, D.; Robinson, M. B.; Rathz, T. J.; Williams, G.

    1998-01-01

    A systematic study on the liquid separation in supercooled Cu-Co and Cu-Fe alloys was performed using a melt fluxing which permits high supercooling to be achieved. Moreover, this method renders it possible to directly measure binodal temperatures and establish metastable liquid miscibility gap (LMG). All phase-separated samples at compositions ranging from 10 to 80 wt pct Co or to 83 wt pct Fe were found to exhibit droplet-shaped morphologies, in spite of various droplet distributions. Uniformly dispersed microstructures were obtained as the minority component was less than 20 vol.%; while beyond this percentage, serious coarsening was brought about. Calculations of the miscibility gap in the Cu-Co system and Stokes movement velocity of Co and Fe droplets in Cu matrix were made to analyze the experimental results.

  11. Study on Supercooling Point and Freezing Point in Floral Organs of Apricot

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Under the environment of an artificial climate chamber, supercooling point (SCP) and freezing point (FP) in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, they turned brown after thawing.

  12. Possible Segregated Ice at the Phoenix Landing Site: Was Liquid Water Involved?

    Science.gov (United States)

    Stoker, C.; Blaney, D.; Hecht, M.; Catling, D.; Pike, W. T.; Mellon, M.; Kounaves, S.; Lemmon, M.

    2008-12-01

    Lander cameras on the Phoenix mission revealed polygonal terrain at the landing site. Areas identified by topography within the work area of the arm included a polygon and a surrounding trough. Two trenches were dug, the first (Goldilocks) on the shoulder of a trough area exposed a bright, hard material and the second (Snow white) in the center of the polygon exposed hard material, but with multispectral properties indistinguishable from soil. Visibile-NIR spectra of the Goldilocks bright material are consistent with slightly dusty ice. When first exposed, a 2 cm chunk of material broke off and was observed to completely disappear in 3 sols, an implied sublmation rate of 100 micrometers per hour. We hypothesize that the Goldilocks bright material is segregated ice. The material is hard, localized, has distinct edges, and was initially covered with only 3 cm of soil, thus was 2cm shallower than the hard layer in the Snow white trench in spite of a more south-facing exposure. A trench dug 40 cm further south of Goldilocks, with similar orientation, reached 18 cm depth without encountering hard material. Plausible mechanisms for emplacement of segregated ice include liquid water pooled into a thermally-produced crack analogous to terrestrial ice wedge polygon formation, snowparticles depositing preferentially in the troughs, and vapor deposition preferentially into cracks (D. Fisher, Icarus 179, 387, 2005). Mission observations were performed relevant to evaluating these formation mechanisms. Wet chemistry analyses of soils suggest they contain Mg(ClO4)2, a soluble hygroscopic salt with a eutectic freezing point of /- 68C. If liquid water moved though the soil and formed the bright deposit in Goldilocks trench, a higher concentration of perchlorate would be expected in the area of the ice. Mg(ClO4)2. 6 H2O would crystallize when the salty water froze, forming white rhombohedral crystals. After scraping away the surface soil, approximately 500 cm2of bright material was

  13. Heterogeneous nucleation from a supercooled ionic liquid on a carbon surface

    Science.gov (United States)

    He, Xiaoxia; Shen, Yan; Hung, Francisco R.; Santiso, Erik E.

    2016-12-01

    Classical molecular dynamics simulations were used to study the nucleation of the crystal phase of the ionic liquid [dmim+][Cl-] from its supercooled liquid phase, both in the bulk and in contact with a graphitic surface of D = 3 nm. By combining the string method in collective variables [Maragliano et al., J. Chem. Phys. 125, 024106 (2006)], with Markovian milestoning with Voronoi tessellations [Maragliano et al., J. Chem. Theory Comput. 5, 2589-2594 (2009)] and order parameters for molecular crystals [Santiso and Trout, J. Chem. Phys. 134, 064109 (2011)], we computed minimum free energy paths, the approximate size of the critical nucleus, the free energy barrier, and the rates involved in these nucleation processes. For homogeneous nucleation, the subcooled liquid phase has to overcome a free energy barrier of ˜85 kcal/mol to form a critical nucleus of size ˜3.6 nm, which then grows into the monoclinic crystal phase. This free energy barrier becomes about 42% smaller (˜49 kcal/mol) when the subcooled liquid phase is in contact with a graphitic disk, and the critical nucleus formed is about 17% smaller (˜3.0 nm) than the one observed for homogeneous nucleation. The crystal formed in the heterogeneous nucleation scenario has a structure that is similar to that of the bulk crystal, with the exception of the layers of ions next to the graphene surface, which have larger local density and the cations lie with their imidazolium rings parallel to the graphitic surface. The critical nucleus forms near the graphene surface separated only by these layers of ions. The heterogeneous nucleation rate (˜4.8 × 1011 cm-3 s-1) is about one order of magnitude faster than the homogeneous rate (˜6.6 × 1010 cm-3 s-1). The computed free energy barriers and nucleation rates are in reasonable agreement with experimental and simulation values obtained for the homogeneous and heterogeneous nucleation of other systems (ice, urea, Lennard-Jones spheres, and oxide glasses).

  14. Quark-gluon plasma freeze-out from a supercooled state?

    CERN Document Server

    Csörgö, T

    1994-01-01

    The quark-gluon plasma, formed in the first 3 fm/c of the heavy ion collisions at RHIC and LHC, supercooles due to nucleation and develops soon a negative pressure in the bag model. The negative pressure yields mechanical instability which may lead to a sudden timelike deflagration to a (super)heated hadron gas. The resulting freeze-out times are shorter than those of the standard nucleation scenario.

  15. Direct measurement of the surface dynamics of supercooled liquid-glycerol by optical scanning a film

    Institute of Scientific and Technical Information of China (English)

    Zhang Fang; Zhang Guo-Feng; Dong Shuang-Li; Sun Jian-Hu; Chen Rui-Yun; Xiao Lian-Tuan; Jia Suo-Tang

    2009-01-01

    The surface dynamics of supercooled liquid-glycerol is studied by scanning the thickness of the glycerol film with single photon detection. Measurements are performed at room temperature well above the glycerol's glass transition temperature. It is shown that the surface dynamics of the glycerol film is very sensitive to the temperature. The linear relationship between the thickness of the film and the viscosity predicted by the Vogel-Fulcher-Tammann-Hesse (VFTH) law is also presented experimentally.

  16. An airborne microwave radiometer and measurements of cloud liquid water

    Institute of Scientific and Technical Information of China (English)

    LEI Hengchi; JIN Dezhen; WEI Chong; SHEN Zhilai

    2003-01-01

    A single-channel (9.5 mm) airborne microwave radiometer with one antenna is developed. The retrieval methods and primary observation results of cloud liquid water and super-cooled cloud liquid water are discussed. The aircraft experiments show that the cloud liquid water and super-cooled liquid water can be sensitively monitored at some level of accuracy by the radiometer. The results of cloud liquid water content are reasonable and correspond well with the surface radar echo intensity. The design of the airborne radiometer and its retrieval methods are feasible, giving it application value.

  17. Real-time observation of the isothermal crystallization kinetics in a deeply supercooled liquid

    Science.gov (United States)

    Zanatta, M.; Cormier, L.; Hennet, L.; Petrillo, C.; Sacchetti, F.

    2017-01-01

    Below the melting temperature Tm, crystals are the stable phase of typical elemental or molecular systems. However, cooling down a liquid below Tm, crystallization is anything but inevitable. The liquid can be supercooled, eventually forming a glass below the glass transition temperature Tg. Despite their long lifetimes and the presence of strong barriers that produces an apparent stability, supercooled liquids and glasses remain intrinsically a metastable state and thermodynamically unstable towards the crystal. Here we investigated the isothermal crystallization kinetics of the prototypical strong glassformer GeO2 in the deep supercooled liquid at 1100 K, about half-way between Tm and Tg. The crystallization process has been observed through time-resolved neutron diffraction for about three days. Data show a continuous reorganization of the amorphous structure towards the alpha-quartz phase with the final material composed by crystalline domains plunged into a low-density, residual amorphous matrix. A quantitative analysis of the diffraction patterns allows determining the time evolution of the relative fractions of crystal and amorphous, that was interpreted through an empirical model for the crystallization kinetics. This approach provides a very good description of the experimental data and identifies a predator-prey-like mechanism between crystal and amorphous, where the density variation acts as a blocking barrier. PMID:28255173

  18. [Anomalous Properties of Water and Aqueous Solutions at Low Temperatures].

    Science.gov (United States)

    Matsumoto, Masakazu

    2015-01-01

    Water has many anomalous properties below the room temperature. The temperature range overlaps with that of the Earth's atmosphere and also with that natural life forms favor. We review the origin of the anomalous properties of water and aqueous solutions in association with the hypothetical second critical point and liquid-liquid phase separation of water hidden in the supercooled state of liquid water.

  19. The formation and physical stability of two-phase solid dispersion systems of indomethacin in supercooled molten mixtures with different matrix formers.

    Science.gov (United States)

    Semjonov, Kristian; Kogermann, Karin; Laidmäe, Ivo; Antikainen, Osmo; Strachan, Clare J; Ehlers, Henrik; Yliruusi, Jouko; Heinämäki, Jyrki

    2017-01-15

    Amorphous solid dispersions (SDs) are a promising approach to improve the dissolution rate of and oral bioavailability of poorly water-soluble drugs. In some cases multi-phase, instead of single-phase, SD systems with amorphous drug are obtained. While it is widely assumed that one-phase amorphous systems are desirable, two-phase systems may still potentially exhibit enhanced stability and dissolution advantages over undispersed systems. The objective of the present study was to understand the solid-state properties of two-phase SDs with amorphous drug and their relation to physical stability. Two different types of excipients for SD formation were used, one being a polymer and the other a small molecule excipient. The supercooled molten SDs of a poorly water-soluble indomethacin (IND) with a graft copolymer, Soluplus® (SOL) and sugar alcohol, xylitol (XYL) were prepared. Supercooled molten SDs of IND with SOL were two-phase glassy suspension in which the amorphous drug was dispersed in an amorphous polymer matrix. A short-term aging of the SDs led to the formation of glassy suspensions where the crystalline drug was dispersed in an amorphous polymer matrix. These were physically stable at room temperature for the time period studied (RT, 23±2°C), but aging at high-humidity conditions (75% RH) recrystallization to metastable α-IND occurred. Interestingly, the SDs with XYL were two-phase amorphous precipitation systems in which the drug was in an amorphous form in the crystalline sugar alcohol matrix. The SDs of IND and XYL exhibited fast drug recrystallization. In conclusion, the preparation method of two-phase systems via co-melting in association with the rapid quench cooling is a feasible method for the formulation of poorly water-soluble drugs. The physical stability of these two-phase systems, however, is dependent on the carrier material and storage conditions.

  20. Deciphering the ecophysiological traits involved during water stress acclimation and recovery of the threatened wild carnation, Dianthus inoxianus.

    Science.gov (United States)

    López-Jurado, Javier; Balao, Francisco; Mateos-Naranjo, Enrique

    2016-12-01

    Dianthus inoxianus is an endangered species endemic from a small littoral area in the SW Spain, with an unusual flowering season under the adverse conditions of dry Mediterranean summer. A greenhouse experiment was designed to assess the physiological traits involved in drought acclimation and recovery of 3-month-old plants. The evolution of plant water status, leaf gas exchange, chlorophyll fluorescence, photosynthetic pigments concentrations and a quantitative analysis of photosynthesis limitations were followed during water stress and re-watering. Our results indicated that the plant water status, Ψw and RWC, only decreased at the end of the drought period (18th day), together with the net photosynthetic rate, AN. Photosynthetic impair was mainly caused by diffusional limitations (SL and MCL) of CO2, as indicated the joint and marked decrease of gs, gm and Ci during drought period, while Vc,max did not vary. After rewatering, leaf water status recovered faster than photosynthetic one, reaching control values on day 1 after recovery, while AN, gm and Ci took 7 days. Additionally, gs showed the slowest recovery taking 15 days, but gs decrease was enough to keep Ψw and RWC at constant values throughout the experiment. Results suggest a high tolerance and recovery of D. inoxianus from severe drought periods. This drought tolerance was also reflected in the stability of its photochemical apparatus and pigments concentrations, as indicated the constant values of Fv/Fm, ФPSII and pigments concentrations through experimental period. However, prolonged drought events due to global climate change could negatively affect the physiological mechanisms of this species.

  1. A note on the solution of water wave scattering problem involving small deformation on a porous channel-bed

    Science.gov (United States)

    Mohapatra, S.; Sarangi, M. R.

    2017-03-01

    The solution of water wave scattering problem involving small deformation on a porous bed in a channel, where the upper surface is bounded above by an infinitely extent rigid horizontal surface, is studied here within the framework of linearized water wave theory. In such a situation, there exists only one mode of waves propagating on the porous surface. A simplified perturbation analysis, involving a small parameter ɛ ( ≪ 1), which measures the smallness of the deformation, is employed to reduce the governing Boundary Value Problem (BVP) to a simpler BVP for the first-order correction of the potential function. The first-order potential function and, hence, the first-order reflection and transmission coefficients are obtained by the method based on Fourier transform technique as well as Green's integral theorem with the introduction of appropriate Green's function. Two special examples of bottom deformation: the exponentially damped deformation and the sinusoidal ripple bed, are considered to validate the results. For the particular example of a patch of sinusoidal ripples, the resonant interaction between the bed and the upper surface of the fluid is attained in the neighborhood of a singularity, when the ripples wavenumbers of the bottom deformation become approximately twice the components of the incident field wavenumber along the positive x-direction. Also, the main advantage of the present study is that the results for the values of reflection and transmission coefficients are found to satisfy the energy-balance relation almost accurately.

  2. Laboratory Test of a Cylindrical Heat Storage Module with Water and Sodium Acetate Trihydrate

    DEFF Research Database (Denmark)

    Dannemand, Mark; Kong, Weiqiang; Johansen, Jakob Berg;

    2016-01-01

    Cylindrical heat storage modules with internal heat exchangers have been tested in a laboratory. The modules were filled with water and sodium acetate trihydrate with additives. The testing focused on the heat content of the storage material and the heat exchange capacity rate during charge...... of the module. For the tests with the phase change materials, the focus was furthermore on the stability of supercooling and cycling stability. Testing the module with sodium acetate trihydrate and 6.4% extra water showed that phase separation increased and the heat released after solidification of supercooled...... phase change material was reduced over 17 test cycles. The heat released after solidification of the supercooled sodium acetate trihydrate with thickening agent and graphite was stable over the test cycles. Stable supercooling was obtained in 7 out of 17 test cycles with the module with sodium acetate...

  3. Factors involved in sustained use of point-of-use water disinfection methods: a field study from Flores Island, Indonesia.

    Science.gov (United States)

    Roma, E; Bond, T; Jeffrey, P

    2014-09-01

    Many scientific studies have suggested that point-of-use water treatment can improve water quality and reduce the risk of infectious diseases. Despite the ease of use and relatively low cost of such methods, experience shows the potential benefits derived from provision of such systems depend on recipients' acceptance of the technology and its sustained use. To date, few contributions have addressed the problem of user experience in the post-implementation phase. This can diagnose challenges, which undermine system longevity and its sustained use. A qualitative evaluation of two household water treatment systems, solar disinfection (SODIS) and chlorine tablets (Aquatabs), in three villages was conducted by using a diagnostic tool focusing on technology performance and experience. Cross-sectional surveys and in-depth interviews were used to investigate perceptions of involved stakeholders (users, implementers and local government). Results prove that economic and functional factors were significant in using SODIS, whilst perceptions of economic, taste and odour components were important in Aquatabs use. Conclusions relate to closing the gap between factors that technology implementers and users perceive as key to the sustained deployment of point-of-use disinfection technologies.

  4. Physiological and metagenomic analyses of microbial mats involved in self-purification of mine waters contaminated with heavy metals

    Directory of Open Access Journals (Sweden)

    Lukasz Drewniak

    2016-08-01

    Full Text Available Two microbial mats found inside two old (gold and uranium mines in Zloty Stok and Kowary located in SW Poland seem to form a natural barrier that traps heavy metals leaking from dewatering systems. We performed complex physiological and metagenomic analyses to determine which microorganisms are the main driving agents responsible for self-purification of the mine waters and identify metabolic processes responsible for the observed features. SEM and energy dispersive X-ray microanalysis showed accumulation of heavy metals on the mat surface, whereas, sorption experiments showed that neither microbial mats were completely saturated with heavy metals present in the mine waters, indicating that they have a large potential to absorb significant quantities of metal. The metagenomic analysis revealed that Methylococcaceae and Methylophilaceae families were the most abundant in both communities, moreover, it strongly suggest that backbones of both mats were formed by filamentous bacteria, such as Leptothrix, Thiothrix, and Beggiatoa. The Kowary bacterial community was enriched with the Helicobacteraceae family, whereas the Zloty Stok community consist mainly of Sphingomonadaceae, Rhodobacteraceae, and Caulobacteraceae families. Functional (culture-based and metagenome (sequence-based analyses showed that bacteria involved in immobilization of heavy metals, rather than those engaged in mobilization, were the main driving force within the analyzed communities. In turn, a comparison of functional genes revealed that the biofilm formation and heavy metal resistance functions are more desirable in microorganisms engaged in water purification than the ability to utilize heavy metals in the respiratory process (oxidation-reduction. These findings provide insight on the activity of bacteria leading, from biofilm formation to self-purification, of mine waters contaminated with heavy metals

  5. The Fish Pathogen Vibrio vulnificus Biotype 2: Epidemiology, Phylogeny, and Virulence Factors Involved in Warm-Water Vibriosis.

    Science.gov (United States)

    Amaro, Carmen; Sanjuán, Eva; Fouz, Belén; Pajuelo, David; Lee, Chung-Te; Hor, Lien-I; Barrera, Rodolfo

    2015-06-01

    Vibrio vulnificus biotype 2 is the etiological agent of warm-water vibriosis, a disease that affects eels and other teleosts, especially in fish farms. Biotype 2 is polyphyletic and probably emerged from aquatic bacteria by acquisition of a transferable virulence plasmid that encodes resistance to innate immunity of eels and other teleosts. Interestingly, biotype 2 comprises a zoonotic clonal complex designated as serovar E that has extended worldwide. One of the most interesting virulence factors produced by serovar E is RtxA13, a multifunctional protein that acts as a lethal factor for fish, an invasion factor for mice, and a survival factor outside the host. Two practically identical copies of rtxA13 are present in all biotype 2 strains regardless of the serovar, one in the virulence plasmid and the other in chromosome II. The plasmid also contains other genes involved in survival and growth in eel blood: vep07, a gene for an outer membrane (OM) lipoprotein involved in resistance to eel serum and vep20, a gene for an OM receptor specific for eel-transferrin and, probably, other related fish transferrins. All the three genes are highly conserved within biotype 2, which suggests that they are under a strong selective pressure. Interestingly, the three genes are related with transferable plasmids, which emphasizes the role of horizontal gene transfer in the evolution of V. vulnificus in nutrient-enriched aquatic environments, such as fish farms.

  6. Crystallization Behavior and Relaxation Dynamics of Supercooled S‑Ketoprofen and the Racemic Mixture along an Isochrone

    DEFF Research Database (Denmark)

    Adrjanowicz, Karolina; Kaminski, Kamil; Paluch, Marian

    2015-01-01

    In this paper, we study crystallization behavior and molecular dynamics in the supercooled liquid state of the pharmaceutically important compound ketoprofen at various thermodynamic conditions. Dielectric relaxation for a racemic mixture was investigated in a wide range of temperatures and press......In this paper, we study crystallization behavior and molecular dynamics in the supercooled liquid state of the pharmaceutically important compound ketoprofen at various thermodynamic conditions. Dielectric relaxation for a racemic mixture was investigated in a wide range of temperatures...... of pure enantiomers and their 50–50 equimolar mixture in the metastable supercooled liquid state. Crystallization kinetic studies revealed that at the same isochronal conditions the behavior of the S-enantiomer and R,S-racemic mixture of ketoprofen is entirely different. This was examined in the context...

  7. In-situ High-energy X-ray Diffraction Study of the Local Structure of Supercooled Liquid Si

    Science.gov (United States)

    Lee, G. W.; Kim, T. H.; Sieve, B.; Gangopadhyay, A. K.; Hyers, R. W.; Rathz, T. J.; Rogers, J. R.; Robinson, D. S.; Kelton, K. F.; Goldman, A. I.

    2005-01-01

    While changes in the coordination number for liquid silicon upon supercooling, signaling an underlying liquid-liquid phase transition, have been predicted, x-ray and neutron measurements have produced conflicting reports. In particular some studies have found an increase in the first shell coordination as temperature decreases in the supercooled regime, while others have reported increases in the coordination number with decreasing temperature. Employing the technique of electrostatic levitation coupled with high energy x-ray diffraction (125 keV), and rapid data acquisition (100ms collection times) using an area detector, we have obtained high quality structural data more deeply into the supercooled regime than has been possible before. No change in coordination number is observed in this temperature region, calling into question previous experimental claims of structural evidence for the existence of a liquid-liquid phase transition.

  8. Slow dynamics and local quasi-equilibrium-relaxation in supercooled colloidal systems

    Energy Technology Data Exchange (ETDEWEB)

    RubI, J M; SantamarIa-Holek, I; Perez-Madrid, A [Department de Fisica Fonamental, Facultat de Fisica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona (Spain)

    2004-06-09

    We present a Fokker-Planck description of supercooled colloidal systems exhibiting slow relaxation dynamics. Assuming the existence of a local quasi-equilibrium state during the relaxation of the system, we derive a non-Markovian Fokker-Planck equation for the non-stationary conditional probability. A generalized Stokes-Einstein relation containing the temperature of the system at local quasi-equilibrium instead of the temperature of the bath is obtained. Our results explain experiments showing that the diffusion coefficient is not proportional to the inverse of the effective viscosity at frequencies related to the diffusion timescale.

  9. Effects of hydrogen-bond environment on single particle and pair dynamics in liquid water

    Indian Academy of Sciences (India)

    Amalendu Chandra; Snehasis Chowdhuri

    2001-10-01

    We have performed molecular dynamics simulations of liquid water at 298 and 258 K to investigate the effects of hydrogen-bond environment on various single-particle and pair dynamical properties of water molecules at ambient and supercooled conditions. The water molecules are modelled by the extended simple point charge (SPC/E) model. We first calculate the distribution of hydrogen-bond environment in liquid water at both temperatures and then investigate how the selfdiffusion and orientational relaxation of a single water molecule and also the relative diffusion and relaxation of the hydrogen-bond of a water pair depend on the nature of the hydrogen-bond environment of the tagged molecules. We find that the various dynamical quantities depend significantly on the hydrogen-bond environment, especially at the supercooled temperature. The present study provides a molecular-level insight into the dynamics of liquid water under ambient and supercooled conditions.

  10. Quasi-elastic neutron scattering studies of the slow dynamics of supercooled and glassy aspirin

    Science.gov (United States)

    Zhang, Yang; Tyagi, Madhusudan; Mamontov, Eugene; Chen, Sow-Hsin

    2012-02-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent β(Q) is independent of the wavevector transfer Q in the measured Q range and (ii) the structural relaxation time τ(Q) follows a power-law dependence on Q. Consequently, the Q-independent structural relaxation time τ0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of τ0 can be fitted with the mode-coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by Tokuyama in the measured temperature range. The calculated dynamic response function χT(Q, t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement langx2rang and the non-Gaussian parameter α2 extracted from the elastic scattering.

  11. Orientational dynamics and energy landscape features of thermotropic liquid crystals: An analogy with supercooled liquids

    Indian Academy of Sciences (India)

    Biman Jana; Biman Bagchi

    2007-09-01

    Recent optical kerr effect (OKE) studies have revealed that orientational relaxation of rodlike nematogens near the isotropic-nematic (I-N) phase boundary and also in the nematic phase exhibit temporal power law decay at intermediate times. Such behaviour has drawn an intriguing analogy with supercooled liquids. Here, we have investigated the single-particle and collective orientational dynamics of a family of model system of thermotropic liquid crystals using extensive computer simulations. Several remarkable features of glassy dynamics are on display including non-exponential relaxation, dynamical heterogeneity, and non-Arrhenius temperature dependence of the orientational relaxation time. Over a temperature range near the I-N phase boundary, the system behaves like a fragile glass-forming liquid. Using proper scaling, we construct the usual relaxation time versus inverse temperature plot and explicitly demonstrate that one can successfully define a density dependent fragility of liquid crystals. The fragility of liquid crystals shows a temperature and density dependence which is remarkably similar to the fragility of glass forming supercooled liquids. Energy landscape analysis of inherent structures shows that the breakdown of the Arrhenius temperature dependence of relaxation rate occurs at a temperature that marks the onset of the growth of the depth of the potential energy minima explored by the system.

  12. Nature of large aggregates in supercooled aqueous solutions of sodium dodecyl sulfate

    Energy Technology Data Exchange (ETDEWEB)

    Franses, E.I. (Purdue Univ., West Lafayette, IN); Davis, H.T.; Miller, W.G.; Scriven, L.E.

    1980-09-18

    Preparations of 2.0 and 5.5 wt % sodium dodecyl sulfate (SDS) in 3.5 wt % (0.6 M) aqueous NaCl are equilibrium micellar solutions above 28/sup 0/C, the Krafft point of the surfactant at this salinity. These systems can be supercooled and remain transparent for hours and days. At 25/sup 0/C at equilibrium they are biphasic, a hydrated crystal phase and an aqueous salt solution phase containing only 0.01/sub 2/ wt % SDS. Conductimetry and /sup 13/C NMR show that these transparent supercooled systems are indeed supersaturated solutions and not microdispersions of the hydrated crystal. The time lag for the onset of nucleation of the crystals depends strongly on stirring details and probably on presence of gas-liquid interface. The big nonequilibrium aggregates present in the supersaturated systems resemble micelles in conductivity and molecular motion, and are likely to be metastable micelles as is presumed by Mazer, Benedek, and Carey. 21 references, 6 figures, 1 table.

  13. Quasi-Elastic Neutron Scattering Studies of the Slow Dynamics of Supercooled and Glassy Aspirin

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yang [ORNL; Tyagi, M. [NCNR and University of Maryland; Mamontov, Eugene [ORNL; Chen, Sow-hsin H [ORNL

    2011-01-01

    Aspirin, also known as acetylsalicylic acid (ASA), is not only a wonderful drug, but also a good glass former. Therefore, it serves as an important molecular system to study the near-arrest and arrested phenomena. In this paper, a high-resolution quasi-elastic neutron scattering (QENS) technique is used to investigate the slow dynamics of supercooled liquid and glassy aspirin from 410 K down to 350 K. The measured QENS spectra can be analyzed with a stretched exponential model. We find that (i) the stretched exponent (Q) is independent of the wave vector transfer Q in the measured Q-range, and (ii) the structural relaxation time (Q) follows a power law dependence on Q. Consequently, the Q-independent structural relaxation time 0 can be extracted for each temperature to characterize the slow dynamics of aspirin. The temperature dependence of 0 can be fitted with the mode coupling power law, the Vogel-Fulcher-Tammann equation and a universal equation for fragile glass forming liquids recently proposed by M. Tokuyama in the measured temperature range. The calculated dynamic response function T(Q,t) using the experimentally determined self-intermediate scattering function of the hydrogen atoms of aspirin shows a direct evidence of the enhanced dynamic fluctuations as the aspirin is increasingly supercooled, in agreement with the fixed-time mean squared displacement x2 and non-Gaussian parameter 2 extracted from the elastic scattering.

  14. Hot and cold water as a supercritical solvent

    Science.gov (United States)

    Fuentevilla, Daphne Anne

    This dissertation addresses the anomalous properties of water at high temperatures near the vapor-liquid critical point and at low temperatures in the supercooled liquid region. The first part of the dissertation is concerned with the concentration dependence of the critical temperature, density, and pressure of an aqueous sodium chloride solution. Because of the practical importance of an accurate knowledge of critical parameters for industrial, geochemical, and biological applications, an empirical equation for the critical locus of aqueous sodium chloride solutions was adopted in 1999 by the International Association for the Properties of Water and Steam (IAPWS) as a guideline. However, since this original Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride was developed, two new theoretical developments occurred, motivating the first part of this dissertation. Here, I present a theory-based formulation for the critical parameters of aqueous sodium chloride solutions as a proposed replacement for the empirical formulation currently in use. This formulation has been published in the International Journal of Thermophysics and recommended by the Executive Committee of IAPWS for adoption as a Revised Guideline on the Critical Locus of Aqueous Solutions of Sodium Chloride. The second part of the dissertation addresses a new concept, considering cold water as a supercritical solvent. Based on the idea of a second, liquid-liquid, critical point in supercooled water, we explore the possibility of supercooled water as a novel supercooled solvent through the thermodynamics of critical phenomena. In 2006, I published a Physical Review letter presenting a parametric scaled equation of state for supercooled-water. Further developments based on this work led to a phenomenological mean-field "two-state" model, clarifying the nature of the phase separation in a polyamorphic single-component liquid. In this dissertation, I modify this two-state model to

  15. Elastic properties of Pd40Cu30Ni10P20 bulk glass in supercooled liquid region

    DEFF Research Database (Denmark)

    Nishiyama, N.; Inoue, A.; Jiang, Jianzhong

    2001-01-01

    In situ ultrasonic measurements for the Pd40Cu30Ni10P20 bulk glass in three states: Glassy solid, supercooled liquid, and crystalline, have been performed. It is found that velocities of both longitudinal and transverse waves and elastic moduli (shear modulus, bulk modulus, Young's modulus, and L...

  16. Optical Kerr effect of liquid water: a new insight into the vibrational and structural dynamics

    CERN Document Server

    Taschin, A; Eramo, R; Righini, R; Torre, R

    2013-01-01

    The liquid and supercooled states of water show a series of anomalies whose nature is lively debated. A key role is attributed to the formation of structural aggregations induced by critical phenomena occurring deep in the supercooled region, not experimentally accessible for bulk water. This explain why, despite the numerous experimental investigations, the nature of water anomalies and the hidden critical processes remain elusive. Here we present a time-resolved optical Kerr effect investigation of the vibrational and relaxation processes in supercooled bulk water. The experiment measures the water intermolecular vibrations and the structural relaxation process in an extended temperature range, and with unpreceded data quality. A mode-coupling analysis of the experimental data allows the characterization of the intermolecular vibrational modes and of their interplay with the structural relaxation process.

  17. PREFACE: Water at interfaces Water at interfaces

    Science.gov (United States)

    Gallo, P.; Rovere, M.

    2010-07-01

    This special issue is devoted to illustrating important aspects and significant results in the field of modeling and simulation of water at interfaces with solutes or with confining substrates, focusing on a range of temperatures from ambient to supercooled. Understanding the behavior of water, in contact with different substrates and/or in solutions, is of pivotal importance for a wide range of applications in physics, chemistry and biochemistry. Simulations of confined and/or interfacial water are also relevant for testing how different its behavior is with respect to bulk water. Simulations and modeling in this field are of particular importance when studying supercooled regions where water shows anomalous properties. These considerations motivated the organization of a workshop at CECAM in the summer of 2009 which aimed to bring together scientists working with computer simulations on the properties of water in various environments with different methodologies. In this special issue, we collected a variety of interesting contributions from some of the speakers of the workshop. We have roughly classified the contributions into four groups. The papers of the first group address the properties of interfacial and confined water upon supercooling in an effort to understand the relation with anomalous behavior of supercooled bulk water. The second group deals with the specific problem of solvation. The next group deals with water in different environments by considering problems of great importance in technological and biological applications. Finally, the last group deals with quantum mechanical calculations related to the role of water in chemical processes. The first group of papers is introduced by the general paper of Stanley et al. The authors discuss recent progress in understanding the anomalies of water in bulk, nanoconfined, and biological environments. They present evidence that liquid water may display 'polymorphism', a property that can be present in

  18. Identification of genes involved in a water stress response in timothy and mapping of orthologous loci in perennial ryegrass

    DEFF Research Database (Denmark)

    Jonavičienė, Kristina; Studer, Bruno; Asp, Torben

    2012-01-01

    In order to characterize the response of selected grasses to water stress, relative water content (RWC) in leaves and quantum efficiency of photosystem 2 (Fv/Fm) were measured in Phleum pratense L., P. bertolonii DC. and P. phleoides H. Karst. during 6 d of water stress. The results indicated dif...

  19. The glass crossover from mean-field Spin-Glasses to supercooled liquids

    Science.gov (United States)

    Rizzo, Tommaso

    2016-03-01

    Stochastic-Beta-Relaxation provides a characterisation of the glass crossover in discontinuous Spin-Glasses and supercoooled liquid. Notably it can be derived through a rigorous computation from a dynamical Landau theory. In this paper, I will discuss the precise meaning of this connection in a language that does not require familiarity with statistical field theory. I will discuss finite-size corrections in mean-field Spin-Glass models and loop corrections in finite-dimensional models that are both described by the dynamical Landau theory considered. Then I will argue that the same Landau theory can be associated to supercooled liquid described by Mode-Coupling Theory invoking a physical principle of time-scale invariance.

  20. A maximum-entropy approach to the adiabatic freezing of a supercooled liquid.

    Science.gov (United States)

    Prestipino, Santi

    2013-04-28

    I employ the van der Waals theory of Baus and co-workers to analyze the fast, adiabatic decay of a supercooled liquid in a closed vessel with which the solidification process usually starts. By imposing a further constraint on either the system volume or pressure, I use the maximum-entropy method to quantify the fraction of liquid that is transformed into solid as a function of undercooling and of the amount of a foreign gas that could possibly be also present in the test tube. Upon looking at the implications of thermal and mechanical insulation for the energy cost of forming a solid droplet within the liquid, I identify one situation where the onset of solidification inevitably occurs near the wall in contact with the bath.

  1. Crystallization behavior of supercooled smectic cholesteryl myristate nanoparticles containing phospholipids as stabilizers

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Koch, Michel; Drechsler, M;

    2005-01-01

    Supercooled smectic nanoparticles based on physiological cholesterol esters are under investigation as a potential novel carrier system for lipophilic drugs. The present study investigates the very complex crystallization behavior of such nanoparticles stabilized with the aid of phospholipids....... Phospholipid and phospholipid/bile salt stabilized cholesteryl myristate dispersions were prepared by high-pressure melt homogenization and characterized by particle size measurements, differential scanning calorimetry, X-ray diffraction and electron microscopy. To obtain fractions with very small smectic...... nanoparticles, selected dispersions were ultracentrifuged. A mixture of cholesteryl myristate and the phospholipid used for the stabilization of the dispersions was also investigated by light microscopy. The nanoparticles usually display a bimodal crystallization event which depends on the thermal treatment...

  2. Local structure of equilibrium and supercooled Ti-Zr-Ni liquids

    Energy Technology Data Exchange (ETDEWEB)

    Lee, G. W.; Gangopadhyay, A.; Hyers, R.; Rathz, T.; Rogers, J.; Robinson, D.; Goldman, A.; Kelton, K.

    2008-05-01

    Recently, we reported the results of experimental in situ high-energy x-ray diffraction studies of electrostatically levitated equilibrium and supercooled metallic elements and alloy liquids, showing evidence for icosahedral short-range ordering (ISRO). In this paper, these studies are extended to binary Ti-Zr and ternary Ti-Zr-Ni alloys. From a cluster-based analysis of the x-ray structure factors, it is concluded that ISRO in the binary alloys becomes progressively more dominant, and the coherence length of the order becomes longer, with the addition of Ni, especially near the concentration of 21 at. % Ni. The effect of chemical interactions among Ti/Zr-Ni and the atomic size on the stabilization of the ISRO is discussed.

  3. Stable glass transformation to supercooled liquid via surface-initiated growth front.

    Science.gov (United States)

    Swallen, Stephen F; Traynor, Katherine; McMahon, Robert J; Ediger, M D; Mates, Thomas E

    2009-02-13

    Highly stable glasses of tris-naphthylbenzene transform into a liquid when annealed above the glass transition temperature T_{g}. In contrast to the predictions of standard models, the observed transformation is spatially inhomogeneous. Secondary ion mass spectrometry experiments on isotopically labeled multilayer films show that the liquid grows into the stable glass with sharp growth fronts initiated at the free surface and at the interface with the substrate. For the free surface, the growth velocity is constant in time and has the same temperature dependence as self-diffusion in the equilibrium supercooled liquid. These stable glasses are packed so efficiently that surfaces and interfaces are required to initiate the transformation to the liquid even well above T_{g}.

  4. Electron Correlation Microscopy: A New Technique for Studying Local Atom Dynamics Applied to a Supercooled Liquid.

    Science.gov (United States)

    He, Li; Zhang, Pei; Besser, Matthew F; Kramer, Matthew Joseph; Voyles, Paul M

    2015-08-01

    Electron correlation microscopy (ECM) is a new technique that utilizes time-resolved coherent electron nanodiffraction to study dynamic atomic rearrangements in materials. It is the electron scattering equivalent of photon correlation spectroscopy with the added advantage of nanometer-scale spatial resolution. We have applied ECM to a Pd40Ni40P20 metallic glass, heated inside a scanning transmission electron microscope into a supercooled liquid to measure the structural relaxation time τ between the glass transition temperature T g and the crystallization temperature, T x . τ determined from the mean diffraction intensity autocorrelation function g 2(t) decreases with temperature following an Arrhenius relationship between T g and T g +25 K, and then increases as temperature approaches T x . The distribution of τ determined from the g 2(t) of single speckles is broad and changes significantly with temperature.

  5. Deformation behavior of Zr-based bulk metallic glass and composite in the supercooled liquid region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Zr-based bulk metallic glass (BMG) with a composition of (Zr75Cu25)78.5Ta4Ni10Al7.5 and a bulk metallic glass matrix composite (BMGC) with a composition of (Zr75Cu25)74.5Ta8Ni10Al7.5 have been prepared by copper-mold casting. The compres-sive deformation behavior of the BMG and BMGC was investigated in the super-cooled region at different temperatures and various strain rates ranging from 8×10-4s-1 to 8×10-2s-1. It was found that both the strain rate and test temperature signifi-cantly affect the deformation behavior of the two alloys. The deformation follows Newtonian flow at low strain rates but non-Newtonian flow at high strain rates. The deformation mechanism for the two kinds of alloys was discussed in terms of the transition state theory.

  6. Correlation between supercooled liquid relaxation and glass poisson’s ratio

    DEFF Research Database (Denmark)

    Sun, Q.J.; Hu, L.N.; Zhou, C.

    2015-01-01

    We report on a correlation between the supercooled liquid (SL) relaxation and glass Poisson’s ratio (v) by comparing the activation energy ratio (r) of the α and the slow β relaxations and the v values for both metallic and nonmetallic glasses. Poisson’s ratio v generally increases with an increase...... in the ratio r and this relation can be described by the empirical function v = 0.5 − A ∗ exp(−B ∗ r), where A and B are constants. This correlation might imply that glass plasticity is associated with the competition between the α and the slow β relaxations in SLs. The underlying physics of this correlation...

  7. Local order in a supercooled colloidal fluid observed by confocal microscopy

    CERN Document Server

    Gasser, U; Weitz, D A

    2003-01-01

    The local order in a supercooled monodisperse colloidal fluid is studied by direct imaging of the particles with a laser scanning confocal microscope. The local structure is analysed with a bond order parameter method, which allows one to discern simple structures that are relevant in this system. As expected for samples that crystallize eventually, a large fraction of the particles are found to sit in surroundings with dominant face-centred cubic or hexagonally close-packed character. Evidence for local structures that contain fragments of icosahedra is found, and, moreover, the icosahedral character increases with volume fraction phi, which indicates that it might play an important role at volume fractions near the glass transition.

  8. Local order in a supercooled colloidal fluid observed by confocal microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gasser, U [Department of Physics and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA (United States); Schofield, Andrew [Department of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Weitz, D A [Department of Physics and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA (United States)

    2003-01-15

    The local order in a supercooled monodisperse colloidal fluid is studied by direct imaging of the particles with a laser scanning confocal microscope. The local structure is analysed with a bond order parameter method, which allows one to discern simple structures that are relevant in this system. As expected for samples that crystallize eventually, a large fraction of the particles are found to sit in surroundings with dominant face-centred cubic or hexagonally close-packed character. Evidence for local structures that contain fragments of icosahedra is found, and, moreover, the icosahedral character increases with volume fraction {phi}, which indicates that it might play an important role at volume fractions near the glass transition.

  9. Effects of cloud condensation nuclei and ice nucleating particles on precipitation processes and supercooled liquid in mixed-phase orographic clouds

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jiwen; Leung, L. Ruby; Rosenfeld, Daniel; DeMott, Paul J.

    2017-01-01

    How orographic mixed-phase clouds respond to the change in cloud condensation nuclei (CCN) and ice nucleating particles (INPs) are highly uncertain. The main snow production mechanism in warm and cold mixed-phase orographic clouds (referred to as WMOCs and CMOCs, respectively, distinguished here as those having cloud tops warmer and colder than -20°C) could be very different. We quantify the CCN and INP impacts on supercooled water content, cloud phases, and precipitation for a WMOC case and a CMOC case, with sensitivity tests using the same CCN and INP concentrations between the WMOC and CMOC cases. It was found that deposition plays a more important role than riming for forming snow in the CMOC case, while the role of riming is dominant in the WMOC case. As expected, adding CCN suppresses precipitation, especially in WMOCs and low INPs. However, this reverses strongly for CCN of 1000 cm-3 and larger. We found a new mechanism through which CCN can invigorate mixed-phase clouds over the Sierra Nevada and drastically intensify snow precipitation when CCN concentrations are high (1000 cm-3 or higher). In this situation, more widespread shallow clouds with a greater amount of cloud water form in the Central Valley and foothills west of the mountain range. The increased latent heat release associated with the formation of these clouds strengthens the local transport of moisture to the windward slope, invigorating mixed-phase clouds over the mountains, and thereby producing higher amounts of snow precipitation. Under all CCN conditions, increasing the INPs leads to decreased riming and mixed-phase fraction in the CMOC as a result of liquid-limited conditions, but has the opposite effects in the WMOC as a result of ice-limited conditions. However, precipitation in both cases is increased by increasing INPs due to an increase in deposition for the CMOC but enhanced riming and deposition in the WMOC. Increasing the INPs dramatically reduces

  10. Primary and secondary relaxations in supercooled eugenol and isoeugenol at ambient and elevated pressures: Dependence on chemical microstructure

    Science.gov (United States)

    Kaminska, E.; Kaminski, K.; Paluch, M.; Ngai, K. L.

    2006-04-01

    Dielectric loss spectra of two glass-forming isomers, eugenol and isoeugenol, measured at ambient and elevated pressures in the normal liquid, supercooled, and glassy states are presented. The isomeric chemical compounds studied differ only by the location of the double bond in the alkyl chain. Above the glass transition temperature Tg, the dielectric loss spectra of both isomers exhibit an excess wing on the high frequency flank of the loss peak of the α relaxation and an additional faster γ process at the megahertz frequency range. By decreasing temperature below Tg at ambient pressure or by elevating pressure above Pg, the glass transition pressure, at constant temperature, the excess wing of isoeugenol shifts to lower frequencies and is transformed into a secondary β-loss peak, while in eugenol it becomes a shoulder. These spectral features enable the β-relaxation time τβ to be determined in the glassy state. These changes indicate that the excess wings in isoeugenol and eugenol are similar and both are secondary β relaxations that are not resolved in the liquid state. While in both isoeugenol and eugenol the loss peak of the β relaxation in the glassy state and the corresponding excess wing in the liquid state shifts to lower frequencies on elevating pressure, the locations of their γ relaxation show little change with increasing pressure. The different pressure sensitivities of the excess wing and γ relaxation are further demonstrated by the nearly perfect superposition of the α-loss peak together with excess wing from the data taken at ambient pressure and at elevated pressure (and higher temperature so as to have the same α-peak frequency), but not the γ-loss peak in both isoeugenol and eugenol. On physical aging isoeugenol, the β-loss peak shifts to lower frequencies, but not the γ relaxation. Basing on these experimental facts, the faster γ relaxation is a local intramolecular process involving a side group and the slower β relaxation

  11. New Mexico cloud super cooled liquid water survey final report 2009.

    Energy Technology Data Exchange (ETDEWEB)

    Beavis, Nick; Roskovensky, John K.; Ivey, Mark D.

    2010-02-01

    Los Alamos and Sandia National Laboratories are partners in an effort to survey the super-cooled liquid water in clouds over the state of New Mexico in a project sponsored by the New Mexico Small Business Assistance Program. This report summarizes the scientific work performed at Sandia National Laboratories during the 2009. In this second year of the project a practical methodology for estimating cloud super-cooled liquid water was created. This was accomplished through the analysis of certain MODIS sensor satellite derived cloud products and vetted parameterizations techniques. A software code was developed to analyze multiple cases automatically. The eighty-one storm events identified in the previous year effort from 2006-2007 were again the focus. Six derived MODIS products were obtained first through careful MODIS image evaluation. Both cloud and clear-sky properties from this dataset were determined over New Mexico. Sensitivity studies were performed that identified the parameters which most influenced the estimation of cloud super-cooled liquid water. Limited validation was undertaken to ensure the soundness of the cloud super-cooled estimates. Finally, a path forward was formulized to insure the successful completion of the initial scientific goals which include analyzing different of annual datasets, validation of the developed algorithm, and the creation of a user-friendly and interactive tool for estimating cloud super-cooled liquid water.

  12. Breaking through the Glass Ceiling: The Correlation Between the Self-Diffusivity in and Krypton Permeation through Deeply Supercooled Liquid Nanoscale Methanol Films

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-28

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures near (100-115 K) the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited ontop of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  13. Breaking through the glass ceiling: The correlation between the self-diffusivity in and krypton permeation through deeply supercooled liquid nanoscale methanol films

    Science.gov (United States)

    Smith, R. Scott; Matthiesen, Jesper; Kay, Bruce D.

    2010-03-01

    Molecular beam techniques, temperature-programmed desorption (TPD), and reflection absorption infrared spectroscopy (RAIRS) are used to explore the relationship between krypton permeation through and the self-diffusivity of supercooled liquid methanol at temperatures (100-115 K) near the glass transition temperature, Tg (103 K). Layered films, consisting of CH3OH and CD3OH, are deposited on top of a monolayer of Kr on a graphene covered Pt(111) substrate at 25 K. Concurrent Kr TPD and RAIRS spectra are acquired during the heating of the composite film to temperatures above Tg. The CO vibrational stretch is sensitive to the local molecular environment and is used to determine the supercooled liquid diffusivity from the intermixing of the isotopic layers. We find that the Kr permeation and the diffusivity of the supercooled liquid are directly and quantitatively correlated. These results validate the rare-gas permeation technique as a tool for probing the diffusivity of supercooled liquids.

  14. Stability of Water/Poly(ethylene oxide)43-b-poly(ε-caprolactone)14/Cyclohexanone Emulsions Involves Water Exchange between the Core and the Bulk.

    Science.gov (United States)

    Flores, Mario E; Martínez, Francisco; Olea, Andrés F; Shibue, Toshimichi; Sugimura, Natsuhiko; Nishide, Hiroyuki; Moreno-Villoslada, Ignacio

    2015-12-31

    The formation of emulsions upon reverse self-association of the monodisperse amphiphilic block copolymer poly(ethylene oxide)43-b-poly(ε-caprolactone)14 in cyclohexanone is reported. Such emulsions are not formed in toluene, chloroform, or dichloromethane. We demonstrate by magnetic resonance spectroscopy the active role of the solvent on the stabilization of the emulsions. Cyclohexanone shows high affinity for both blocks, as predicted by the Hansen solubility parameters, so that the copolymer chains are fully dissolved as monomeric chains. In addition, the solvent is able to produce hydrogen bonding with water molecules. Water undergoes molecular exchange between water molecules associated with the polymer and water molecules associated with the solvent, dynamics of major importance for the stabilization of the emulsions. Association of polymeric chains forming reverse aggregates is induced by water over a concentration threshold of 5 wt %. Reverse copolymer aggregates show submicron average hydrodynamic diameters, as seen by dynamic light scattering, depending on the polymer and water concentration.

  15. Protein tyrosine phosphatase is possibly involved in cellular signal transduction and the regulation of ABA accumulation in response to water deficit in Maize L. coleoptile

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Water deficit-induced ABA accumulation is an ideal model or "stimulus-response" system to investigate cellular stress signaling in plant cells, using such a model the cellular stress signaling triggered by water deficit was investigated in Maize L. coleoptile. Water deficit-induced ABA accumulation was sensitively blocked by NaVO3, a potent inhibitor both to plasma membrane H+-ATPase (PM-H+- ATPase) and protein tyrosine phosphatase (PTPase). However, while PM- H+-ATPase activity was unaffected under water deficit and PM- H+-ATPase activator did not induce an ABA accumulation instead of water deficit, water deficit induced an increase in the protein phosphatase activity, and furthermore, ABA accumulation was inhibited by PAO, a specific inhibitor of PTPase. These results indicate that protein phosphtases may be involved in the cellular signaling in response to water deficit. Further studies identified at least four species of protein phosphtase as assayed by using pNPP as substrate, among which one component was especially sensitive to NaVO3. The NaVO3-sensitive enzyme was purified and finally showed a protein band about 66 kD on SDS/PAGE. The purified enzyme showed a great activity to some specific PTPase substrates at pH 6.0. In addition to NaVO3, the enzyme was also sensitive to some other PTPase inhibitors such as Zn2+ and MO33+, but not to Ca2+ and Mg2+, indicating that it might be a protein tyrosine phosphatase. Interestingly, the purified enzyme could be deactivated by some reducing agent DTT, which was previously proved to be an inhibitor of water deficit-induced ABA accumulation. This result further proved that PTPase might be involved in the cellular signaling of ABA accumulation in response to water deficit.

  16. Involvement of stakeholders in the water quality monitoring and surveillance system: The case of Mzingwane Catchment, Zimbabwe

    Science.gov (United States)

    Nare, Lerato; Love, David; Hoko, Zvikomborero

    Stakeholder participation is viewed as critical in the current water sector reforms taking place in the Southern African region. In Zimbabwe, policies and legislation encourage stakeholder participation. A study was undertaken to determine the extent of stakeholder participation in water quality monitoring and surveillance at the operational level, and also to assess indigenous knowledge and practices in water quality monitoring. Two hundred and forty one questionnaires were administered in Mzingwane Catchment, the portion of the Limpopo Basin that falls within Zimbabwe. The focus was on small users in rural communities, whose experiences were captured using a questionnaire and focus group discussions. Extension workers, farmers and NGOs and relevant sector government ministries and departments were also interviewed and a number of workshops held. Results indicate that there is very limited stakeholder participation despite the presence of adequate supportive structures and organisations. For the Zimbabwe National Water Authority (ZINWA), stakeholders are the paying permit holders to whom feedback is given following analysis of samples. However, the Ministry of Health and Child Welfare generally only releases information to rural communities when it is deemed necessary for their welfare. There are no guidelines on how a dissatisfied member of the public can raise a complaint - although some stakeholders carry such complaints to Catchment Council meetings. With regard to water quality, the study revealed widespread use of indigenous knowledge and practice by communities. Such knowledge is based on smell, taste, colour and odour perceptions. Residents are generally more concerned about the physical parameters than the bacteriological quality of water. They are aware of what causes water pollution and the effects of pollution on human health, crops, animals and aquatic ecology. They have ways of preventing pollution and appropriate interventions to take when a source

  17. Pressure Induced Liquid-to-Liquid Transition in Zr-based Supercooled Melts and Pressure Quenched Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Dmowski, W.; Gierlotka, S.; Wang, Z.; Yokoyama, Y.; Palosz, B.; Egami, T.

    2017-07-26

    Through high-energy x-ray diffraction and atomic pair density function analysis we find that Zr-based metallic alloy, heated to the supercooled liquid state under hydrostatic pressure and then quenched to room temperature, exhibits a distinct glassy structure. The PDF indicates that the Zr-Zr distances in this glass are significantly reduced compared to those quenched without pressure. Annealing at the glass transition temperature at ambient pressure reverses structural changes and the initial glassy state is recovered. This result suggests that pressure causes a liquid-to-liquid phase transition in this metallic alloy supercooled melt. Such a pressure induced transition is known for covalent liquids, but has not been observed for metallic liquids. The High Pressure Quenched glasses are stable in ambient conditions after decompression.

  18. Non-contact property measurements of liquid and supercooled ceramics with a hybrid electrostatic-aerodynamic levitation furnace

    OpenAIRE

    Ishikawa, Takehiko; Yoda, Shinichi; Paradis, Paul-Francois; 石川 毅彦; 依田 真一

    2005-01-01

    The use of an hybrid pressurized electrostatic-aerodynamic levitation furnace and procedures developed by the Japan Aerospace Exploration Agency overcame the contamination problems associated with the processing of ceramics under extreme temperature conditions. This made possible property measurements over wide temperature ranges that cover the superheated as well as the supercooled states. In this study, samples of various ceramics were levitated and their densities were found as a function ...

  19. Involvement of 14-3-3 protein GRF9 in root growth and response under polyethylene glycol-induced water stress.

    Science.gov (United States)

    He, Yuchi; Wu, Jingjing; Lv, Bing; Li, Jia; Gao, Zhiping; Xu, Weifeng; Baluška, František; Shi, Weiming; Shaw, Pang Chui; Zhang, Jianhua

    2015-04-01

    Plant 14-3-3 proteins are phosphoserine-binding proteins that regulate a wide array of targets via direct protein-protein interactions. In this study, the role of a 14-3-3 protein, GRF9, in plant response to water stress was investigated. Arabidopsis wild-type, GRF9-deficient mutant (grf9), and GRF9-overexpressing (OE) plants were treated with polyethylene glycol (PEG) to induce mild water stress. OE plant showed better whole-plant growth and root growth than the wild type under normal or water stress conditions while the grf9 mutant showed worse growth. In OE plants, GRF9 favours the allocation of shoot carbon to roots. In addition, GRF9 enhanced proton extrusion, mainly in the root elongation zone and root hair zone, and maintained root growth under mild water stress. Grafting among the wild type, OE, and grf9 plants showed that when OE plants were used as the scion and GRF9 was overexpressed in the shoot, it enhanced sucrose transport into the root, and when OE plants were used as rootstock and GRF9 was overexpressed in the root, it caused more release of protons into the root surface under water stress. Taken together, the results suggest that under PEG-induced water stress, GRF9 is involved in allocating more carbon from the shoot to the root and enhancing proton secretion in the root growing zone, and this process is important for root response to mild water stress.

  20. Molecular dynamics of the supercooled pharmaceutical agent posaconazole studied via differential scanning calorimetry and dielectric and mechanical spectroscopies.

    Science.gov (United States)

    Adrjanowicz, K; Kaminski, K; Wlodarczyk, P; Grzybowska, K; Tarnacka, M; Zakowiecki, D; Garbacz, G; Paluch, M; Jurga, S

    2013-10-07

    This paper presents comprehensive studies on the molecular dynamics of a pharmaceutically important substance, posaconazole. In order to characterize relaxation dynamics in the supercooled liquid and glassy states, dielectric and mechanical spectroscopies were applied. Dielectric data have indicated multiple relaxation processes that appear above and below the glass transition temperature Tg (τα=100 s) of posaconazole. From the curvature of the dielectric log10(τα) versus inverse of temperature dependence, we determine so-called "fragility", being a very popular parameter for classifying the structural dynamics of supercooled liquids and polymers. From the calculations, we get m=150, which means that is one of the most fragile glass-forming liquids. In this paper, the relaxation dynamics of supercooled posaconazole extracted from the dielectric response function was also confronted with shear-mechanical relaxation. Finally, we have also presented a direct comparison of the fragility and the number of dynamically correlated molecules Nc determined from dynamic calorimetry curves and dielectric and mechanical spectroscopies, showing a clear deviation in the picture of glass-transition dynamics generated by calorimetric and spectroscopic techniques.

  1. Mechanism of Nano-fluorocarbon Coating Restraining Ice Blocking in Supercooled Heat Exchanger%纳米氟碳涂层抑制过冷却器冰堵的机理

    Institute of Scientific and Technical Information of China (English)

    王虹; 何国庚; 田奇琦; 杨丽媛

    2012-01-01

    Ice slurry has been widely used in many fields because of its thermal properties, and ice-making technology has become a focus of study. Dynamic ice-making with supercooled water is one of the most promising method in making ice slurries, but the major defect of this method is that the ice blocking easily take place in the supercooled heat exchanger. Based on the theory of water crystallization and the analysis of the influence factors of ice blocking, a nano-fluorocarbon coating was used to improve the surface conditions of the supercooled heat exchanger and to restrain water from freezing. It is concluded that the nano-fluorocarbon coating will effectively restrain crystallization on the wall and improve the efficiency of the ice-making unit, which results in the decrease of ice blocking and the energy consumption. The investigation will benefit in developing and improving anti-icing techniques.%冰浆由于良好的热物特性,在许多领域得到广泛的应用,其制取方式也成为关注的焦点.过冷水动态制冰是目前最有发展前途的制取冰浆方式之一,但其主要缺陷是过冷却器易发生冰堵.在此,基于水溶液结晶的机理,从影响过冷却器冰堵的因素出发,指出纳米氟碳表面改性材料可改善表面状况,有效抑制壁面结冰,减少制冰过程中的冰堵问题,提高整个系统的制冰效率,降低能耗.纳米氟碳涂层抑制过冷却器冰堵的机理对进一步深化和开发新一代防结冰技术有一定意义.

  2. Remote Sensing of Supercooled Cloud Layers in Cold Climate Using Ground Based Integrated Sensors System and Comparison with Pilot Reports and model forecasts

    Science.gov (United States)

    Boudala, Faisal; Wu, Di; Gultepe, Ismail; Anderson, Martha; turcotte, marie-france

    2017-04-01

    In-flight aircraft icing is one of the major weather hazards to aviation . It occurs when an aircraft passes through a cloud layer containing supercooled drops (SD). The SD in contact with the airframe freezes on the surface which degrades the performance of the aircraft.. Prediction of in-flight icing requires accurate prediction of SD sizes, liquid water content (LWC), and temperature. The current numerical weather predicting (NWP) models are not capable of making accurate prediction of SD sizes and associated LWC. Aircraft icing environment is normally studied by flying research aircraft, which is quite expensive. Thus, developing a ground based remote sensing system for detection of supercooled liquid clouds and characterization of their impact on severity of aircraft icing one of the important tasks for improving the NWPs based predictions and validations. In this respect, Environment and Climate Change Canada (ECCC) in cooperation with the Department of National Defense (DND) installed a number of specialized ground based remote sensing platforms and present weather sensors at Cold Lake, Alberta that includes a multi-channel microwave radiometer (MWR), K-band Micro Rain radar (MRR), Ceilometer, Parsivel distrometer and Vaisala PWD22 present weather sensor. In this study, a number of pilot reports confirming icing events and freezing precipitation that occurred at Cold Lake during the 2014-2016 winter periods and associated observation data for the same period are examined. The icing events are also examined using aircraft icing intensity estimated using ice accumulation model which is based on a cylindrical shape approximation of airfoil and the Canadian High Resolution Regional Deterministic Prediction System (HRDPS) model predicted LWC, median volume diameter and temperature. The results related to vertical atmospheric profiling conditions, surface observations, and the Canadian High Resolution Regional Deterministic Prediction System (HRDPS) model

  3. Transient behavior of square pulsed supercooling for TE devices%脉冲方波驱动强化热电制冷的瞬态特性

    Institute of Scientific and Technical Information of China (English)

    毛佳妮; 陈焕新; 杨亚新; 王小龙; 张恩泉

    2013-01-01

    采用有限差分法对脉冲电压驱动下的瞬态热电效应及其动态特性过程进行了理论分析,探索了非稳态工况下帕尔帖效应、焦耳热效应与傅里叶导热效应之间的耦合关系及其关键制约因素对制冷性能的影响规律,进而探讨了脉冲驱动强化热电制冷性能的作用机理。分析结果得到,在合理电压域值内采用主动控制方法,对热电模块周期性施加数倍于稳态工况理想电压的脉冲突变电压,有益于充分利用帕尔贴制冷效应而推迟出现以焦耳热和傅里叶热耗散形式为主的内部热积聚对热电模块冷端引起的负效应,并能瞬态实现冷端面的制冷强化作用和最大程度实现输入电能的有效转换。该结论不仅为进一步提出脉冲驱动模式的优化控制策略提供了理论依据,也为瞬态热电制冷效应的应用开辟了一条新思路。%Based on a numerical solution involving ti me-dependent imposed square voltage pulse and time-dependent thermal boundary conditions, the transient supercooling behavior was theoretically analyzed, as well as the response to the pulse operation parameters during the periods of pulse start-up, pulse-on time and pulse-off time, which was served as a theoretical basis for exploiting the coupling interaction of the thermoelectric effects (Peltier cooling effect, Joule heating effect and Fourier thermal effect) on the heat diffusion in the short time scale. The results indicate that, the transient thermoelectric supercooling effect can be enhanced by keeping on increasing the Peltier cooling effect as the additional cooling capacity for a period long enough against the earlier arrival of the excessively the Joule heating effect and Fourier heat conduction effect arriving at the cold junction, in which a transient cold spike can be produced by superimposing an additional shaped voltage pulse of the reasonable range on the original steady-state optimum value. The

  4. Freezing of water droplets colliding with kaolinite particles

    DEFF Research Database (Denmark)

    Svensson, Erik Anders; Delval, Christophe Eric Ludovic; Freiherr von Und zu Hessberg, P J H;

    2009-01-01

    Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditions freezing 5 was observed to occur below 2...... studies to describe freezing rates are appropriate for kaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed....

  5. ESKIMO1 is a key gene involved in water economy as well as cold acclimation and salt tolerance

    DEFF Research Database (Denmark)

    Bouchabke-Coussa, O.; Quashie, M.L.; Seoane, Jose Miguel

    2008-01-01

    Background: Drought is a major social and economic problem resulting in huge yield reduction in the field. Today's challenge is to develop plants with reduced water requirements and stable yields in fluctuating environmental conditions. Arabidopsis thaliana is an excellent model for identifying p...

  6. Supercooling Self-Assembly of Magnetic Shelled Core/Shell Supraparticles.

    Science.gov (United States)

    Zheng, Xiaotong; Yan, Bingyun; Wu, Fengluan; Zhang, Jinlong; Qu, Shuxin; Zhou, Shaobing; Weng, Jie

    2016-09-14

    Molecular self-assembly has emerged as a powerful technique for controlling the structure and properties of core/shell structured supraparticles. However, drug-loading capacities and therapeutic effects of self-assembled magnetic core/shell nanocarriers with magnetic nanoparticles in the core are limited by the intervention of the outer organic or inorganic shell, the aggregation of superparamagnetic nanoparticles, the narrowed inner cavity, etc. Here, we present a self-assembly approach based on rebalancing hydrogen bonds between components under a supercooling process to form a new core/shell nanoscale supraparticle with magnetic nanoparticles as the shell and a polysaccharide as a core. Compared with conventional iron oxide nanoparticles, this magnetic shelled core/shell nanoparticle possesses an optimized inner cavity and a loss-free outer magnetic property. Furthermore, we find that the drug-loaded magnetic shelled nanocarriers showed interesting in vitro release behaviors at different pH conditions, including "swelling-broken", "dissociating-broken", and "bursting-broken" modes. Our experiments demonstrate the novel design of the multifunctional hybrid nanostructure and provide a considerable potential for the biomedical applications.

  7. Understanding the nonlinear dynamics of driven particles in supercooled liquids in terms of an effective temperature

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, Carsten F. E., E-mail: c.schroer@uni-muenster.de [Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster (Germany); NRW Graduate School of Chemistry, Wilhelm-Klemm-Straße 10, 48149 Münster (Germany); Heuer, Andreas, E-mail: andheuer@uni-muenster.de [Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster (Germany); Center of Nonlinear Science, Corresstraße 2, 48149 Münster (Germany); Center for Multiscale Theory and Computation, Corrensstraße 40, 48149 Münster (Germany)

    2015-12-14

    In active microrheology, the mechanical properties of a material are tested by adding probe particles which are pulled by an external force. In case of supercooled liquids, strong forcing leads to a thinning of the host material which becomes more pronounced as the system approaches the glass transition. In this work, we provide a quantitative theoretical description of this thinning behavior based on the properties of the Potential Energy Landscape (PEL) of a model glass-former. A key role plays the trap-like nature of the PEL. We find that the mechanical properties in the strongly driven system behave the same as in a quiescent system at an enhanced temperature, giving rise to a well-characterized effective temperature. Furthermore, this effective temperature turns out to be independent of the chosen observable and individually shows up in the thermodynamic and dynamic properties of the system. Based on this underlying theoretical understanding, we can estimate its dependence on temperature and force by the PEL-properties of the quiescent system. We furthermore critically discuss the relevance of effective temperatures obtained by scaling relations for the description of out-of-equilibrium situations.

  8. Dynamic heterogeneity in crossover spin facilitated model of supercooled liquid and fractional Stokes-Einstein relation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seo-Woo; Kim, Soree; Jung, YounJoon, E-mail: yjjung@snu.ac.kr [Department of Chemistry, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2015-06-28

    Kinetically constrained models have gained much interest as models that assign the origins of interesting dynamic properties of supercooled liquids to dynamical facilitation mechanisms that have been revealed in many experiments and numerical simulations. In this work, we investigate the dynamic heterogeneity in the fragile-to-strong liquid via Monte Carlo method using the model that linearly interpolates between the strong liquid-like behavior and the fragile liquid-like behavior by an asymmetry parameter b. When the asymmetry parameter is sufficiently small, smooth fragile-to-strong transition is observed both in the relaxation time and the diffusion constant. Using these physical quantities, we investigate fractional Stokes-Einstein relations observed in this model. When b is fixed, the system shows constant power law exponent under the temperature change, and the exponent has the value between that of the Frederickson-Andersen model and the East model. Furthermore, we investigate the dynamic length scale of our systems and also find the crossover relation between the relaxation time. We ascribe the competition between energetically favored symmetric relaxation mechanism and entropically favored asymmetric relaxation mechanism to the fragile-to-strong crossover behavior.

  9. Hard rhenium–boron–cobalt amorphous alloys with a wide supercooled liquid region

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianfeng, E-mail: jfwang316@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhu, Shijie; Wang, Liguo; Guan, Shaokang [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Li, Ran; Zhang, Tao [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-10-01

    Novel Re–B–Co amorphous alloys with compositions of Re{sub 65−x}B{sub 35}Co{sub x} (at%, x=25, 30, 35, 40, 45, and 50) were fabricated by single-roller melt spinning. These alloys were found to exhibit a clear glass transition phenomenon. The width of supercooled liquid region (ΔT{sub x}) is in the range of 52–71 K. Such a large ΔT{sub x} allows us to produce amorphous alloy bulks by thermoplastic forming. The Vickers hardness is up to 19.10 GPa for the Re{sub 40}B{sub 35}Co{sub 25} alloy, which is close to that reported for some hard covalent crystals. Thus, the present alloys with a combination of large ΔT{sub x} and high hardness are expected to be used as a new type of structural materials. Furthermore, the relationships of hardness with glass transition temperature and Young's modulus were also discussed.

  10. Understanding the nonlinear dynamics of driven particles in supercooled liquids in terms of an effective temperature

    Science.gov (United States)

    Schroer, Carsten F. E.; Heuer, Andreas

    2015-12-01

    In active microrheology, the mechanical properties of a material are tested by adding probe particles which are pulled by an external force. In case of supercooled liquids, strong forcing leads to a thinning of the host material which becomes more pronounced as the system approaches the glass transition. In this work, we provide a quantitative theoretical description of this thinning behavior based on the properties of the Potential Energy Landscape (PEL) of a model glass-former. A key role plays the trap-like nature of the PEL. We find that the mechanical properties in the strongly driven system behave the same as in a quiescent system at an enhanced temperature, giving rise to a well-characterized effective temperature. Furthermore, this effective temperature turns out to be independent of the chosen observable and individually shows up in the thermodynamic and dynamic properties of the system. Based on this underlying theoretical understanding, we can estimate its dependence on temperature and force by the PEL-properties of the quiescent system. We furthermore critically discuss the relevance of effective temperatures obtained by scaling relations for the description of out-of-equilibrium situations.

  11. Molecular dynamics of supercooled ionic liquids studied by light scattering and dielectric spectroscopy

    Science.gov (United States)

    Pabst, Florian; Gabriel, Jan; Weigl, Peter; Blochowicz, Thomas

    2017-09-01

    We investigate molecular dynamics of two supercooled room temperature ionic liquids (RTILs) above of their glass transition temperature by means of dynamic light scattering and broadband dielectric spectroscopy from nanoseconds up to ≈105s . We show that a direct comparison of the raw data of these two techniques allows us to identify the reorientation of ions in the dielectric data, giving experimental evidence to a very recently proposed model of Gainaru et al. [1], stating that the conductivity process in ionic liquids takes place through a reorientational step of ions escaping their cage formed by surrounding counterions. Within this approach we can also understand the apparent decoupling of time constants from dielectric spectroscopy and light scattering, often found in ionic liquids, in a very natural way. Furthermore, as a consequence of knowing the reorientational part of the dielectric spectrum, we are able to show that two more processes contribute to these spectra, which are due to electrode polarization effects. The relative position of all three contributions vary among the systems and may overshadow each other, thus complicating the data analysis and favor misinterpretations.

  12. Water

    Science.gov (United States)

    ... www.girlshealth.gov/ Home Nutrition Nutrition basics Water Water Did you know that water makes up more ... to drink more water Other drinks How much water do you need? top Water is very important, ...

  13. The involvement of citizens and water management: Neighborhood committees leaders in Ciudad Juárez, Chihuahua

    Directory of Open Access Journals (Sweden)

    Gustavo Córdova Bojórquez

    2005-07-01

    Full Text Available This paper seeks to analyze public participation in water management through a survey applied to the leaders of neighborhood committees in Ciudad Juarez, Chihuahua. As part of the methodology, two variables —external and internal influences— and fourteen indicators were utilized. Results show that neighborhood committees, as a public participation structure, are in crisis. The structure shows both internal and external signs of breaking up: there are no clear mechanisms of summons or participation, nor are there any adecuate mechanisms capable of articulating demands and government authority, insofar as external political agents have been allowed to participate in internal management and committee issues. For this reason, the capacity of local neighborhood committees to make decisions regarding city water management is placed in doubt.

  14. Polyamine regulates tolerance to water stress in leaves of white clover associated with antioxidant defense and dehydrin genes via involvement in calcium messenger system and hydrogen peroxide signaling

    Directory of Open Access Journals (Sweden)

    Zhou eLi

    2015-10-01

    Full Text Available Endogenous polyamine (PA may play a critical role in tolerance to water stress in plants acting as a signaling molecule activator. Water stress caused increases in endogenous PA content in leaves, including putrescine (Put, spermidine (Spd, and spermine (Spm. Exogenous application of Spd could induce the instantaneous H2O2 burst and accumulation of cytosolic free Ca2+, and activate NADPH oxidase and CDPK gene expression in cells. To a great extent, PA biosynthetic inhibitor reduced the water stress-induced H2O2 accumulation, free cytosolic Ca2+ release, antioxidant enzyme activities and genes expression leading to aggravate water stress-induced oxidative damage, while these suppressing effects were alleviated by the addition of exogenous Spd, indicating PA was involved in water stress-induced H2O2 and cytosolic free Ca2+ production as well as stress tolerance. Dehydrin genes (Y2SK, Y2K, and SK2 were showed to be highly responsive to exogenous Spd. PA-induced antioxidant defense and dehydrin genes expression could be blocked by the scavenger of H2O2 and the inhibitors of H2O2 generation or Ca2+ channels blockers, a calmodulin antagonist, as well as the inhibitor of CDPK. These findings suggested that PA regulated tolerance to water stress in white clover associated with antioxidant defenses and dehydrins via involvement in the calcium messenger system and H2O2 signaling pathways. PA-induced H2O2 production required Ca2+ release, while PA-induced Ca2+ release was also essential for H2O2 production, suggesting an interaction between PA-induced H2O2 and Ca2+ signaling.

  15. A tomato bZIP transcription factor, SlAREB, is involved in water deficit and salt stress response.

    Science.gov (United States)

    Hsieh, Tsai-Hung; Li, Chia-Wen; Su, Ruey-Chih; Cheng, Chiu-Ping; Sanjaya; Tsai, Yi-Chien; Chan, Ming-Tsair

    2010-05-01

    Abiotic stresses such as cold, water deficit, and salt stresses severely reduce crop productivity. Tomato (Solanum lycopersicum) is an important economic crop; however, not much is known about its stress responses. To gain insight into stress-responsive gene regulation in tomato plants, we identified transcription factors from a tomato cDNA microarray. An ABA-responsive element binding protein (AREB) was identified and named SlAREB. In tomato protoplasts, SlAREB transiently transactivated luciferase reporter gene expression driven by AtRD29A (responsive to dehydration) and SlLAP (leucine aminopeptidase) promoters with exogenous ABA application, which was suppressed by the kinase inhibitor staurosporine, indicating that an ABA-dependent post-translational modification is required for the transactivation ability of SlAREB protein. Electrophoretic mobility shift assays showed that the recombinant DNA-binding domain of SlAREB protein is able to bind AtRD29A and SlLAP promoter regions. Constitutively expressed SlAREB increased tolerance to water deficit and high salinity stresses in both Arabidopsis and tomato plants, which maintained PSII and membrane integrities as well as water content in plant bodies. Overproduction of SlAREB in Arabidopsis thaliana and tomato plants regulated stress-related genes AtRD29A, AtCOR47, and SlCI7-like dehydrin under ABA and abiotic stress treatments. Taken together, these results show that SlAREB functions to regulate some stress-responsive genes and that its overproduction improves plant tolerance to water deficit and salt stress.

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

    Science.gov (United States)

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

    2015-10-27

    Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, T(g) . Here we report a universal water-content, X(aqu) , dependence of T(g) for aqueous solutions. Solutions with X(aqu)>X(cr)(aqu)vitrify/devitrify at a constant temperature, ~T(g) , referring to freeze-concentrated phase with X(aqu)left behind ice crystallization. Those solutions with X(aqu)recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of T(g) by annealing is attributable to freeze-concentrated phase of solutions instead of 'liquid II phase of water'. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution.

  17. Effect of temperature on the low-frequency vibrational spectrum and relative structuring of hydration water around a single-stranded DNA.

    Science.gov (United States)

    Chakraborty, Kaushik; Bandyopadhyay, Sanjoy

    2015-01-07

    Molecular dynamics simulations of the single-stranded DNA oligomer (5'-CGCGAAT TCGCG-3') in aqueous solution have been carried out at different temperatures between 160 K and 300 K. The effects of temperature on the low-frequency vibrational spectrum and local structural arrangements of water molecules hydrating the DNA strand have been explored in detail. The low-frequency density of states distributions reveal that increasingly trapped transverse water motions play a dominant role in controlling the band corresponding to O⋯O⋯O bending or transverse oscillations of hydration water at supercooled temperatures. In addition, presence of a broad band around 260 (±20) cm(-1) under supercooled conditions indicates transformation from high density liquid-like structuring of hydration water at higher temperatures to that of a low density liquid at lower temperatures. It is found that long-range correlations between the supercooled hydration water molecules arise due to such local structural transition around the DNA oligomer.

  18. Multi-Isotopic (o, H, Sr, Li) Tracing of the Fluxes Involved in the Water Status of a Peatland (la Sauvetat, Massif Central, France)

    Science.gov (United States)

    Agnès, B.; Negrel, P. J.; Millot, R.; Clotilde, B.

    2010-12-01

    The bio-diversity (vegetation and fauna) of peatlands, like all wetlands ecosystems, are strongly fragile as they are requiring very specific wet conditions. In the past 20 years, increasing efforts were engaged to restore degraded wetlands, to create new wetlands where they have been totally lost and to manage wetlands sustainably in order to assess their multiple benefits. However, engaging specific actions to restore and preserve wetlands require an important knowledge on the water cycle in such systems. In this study, we propose to use chemical and multi-isotopic approaches combined with hydrological measurements (piezometric level and stream flow measurements) to trace the fluxes of water and dissolved element involved in the “Narces de la Sauvetat” peatland (France) and for the stream draining the area. Aims are to evaluate the water status of this ecosystem as well as the origin of dissolved elements and possible anthropogenic impacts. These approaches clearly demonstrated their effectiveness to improve the knowledge on the hydrological functioning of wetlands ecosystems. Main results are (1) at least three fluxes with distinct chemical and isotopic signatures are providing water supplies to peatland (Sr and stable isotopes), (2) water flow that comes out of the peatland through the stream is certainly negligible (Li isotopes) and 3) water within the peat land exhibits Sr and Li -isotopes values consistent with carbonate amendments inputs used in local agriculture. The outcomes of this study are that peatland ecosystem water balance is poorly affected by its outlet but are strongly controlled by groundwater replenishment. This could lead to a better adjustment of decision maker choices to maintain the water balance of the peatland, which is essential for the preservation of this fragile ecosystem. This study also opens a new field for Li isotope investigations in hydro-systems and highlights the possibility of using Li isotopes as environmental tracers.

  19. Arabidopsis ECERIFERUM9 Involvement in Cuticle Formation and Maintenance of Plant Water Status1[W][OA

    Science.gov (United States)

    Lü, Shiyou; Zhao, Huayan; Des Marais, David L.; Parsons, Eugene P.; Wen, Xiaoxue; Xu, Xiaojing; Bangarusamy, Dhinoth K.; Wang, Guangchao; Rowland, Owen; Juenger, Thomas; Bressan, Ray A.

    2012-01-01

    Mutation of the ECERIFERUM9 (CER9) gene in Arabidopsis (Arabidopsis thaliana) causes elevated amounts of 18-carbon-length cutin monomers and a dramatic shift in the cuticular wax profile (especially on leaves) toward the very-long-chain free fatty acids tetracosanoic acid (C24) and hexacosanoic acid (C26). Relative to the wild type, cer9 mutants exhibit elevated cuticle membrane thickness over epidermal cells and cuticular ledges with increased occlusion of the stomatal pore. The cuticular phenotypes of cer9 are associated with delayed onset of wilting in plants experiencing water deficit, lower transpiration rates, and improved water use efficiency measured as carbon isotope discrimination. The CER9 protein thus encodes a novel determinant of plant drought tolerance-associated traits, one whose deficiency elevates cutin synthesis, redistributes wax composition, and suppresses transpiration. Map-based cloning identified CER9, and sequence analysis predicted that it encodes an E3 ubiquitin ligase homologous to yeast Doa10 (previously shown to target endoplasmic reticulum proteins for proteasomal degradation). To further elucidate CER9 function, the impact of CER9 deficiency on interactions with other genes was examined using double mutant and transcriptome analyses. For both wax and cutin, cer9 showed mostly additive effects with cer6, long-chain acyl-CoA synthetase1 (lacs1), and lacs2 and revealed its role in early steps of both wax and cutin synthetic pathways. Transcriptome analysis revealed that the cer9 mutation affected diverse cellular processes, with primary impact on genes associated with diverse stress responses. The discovery of CER9 lays new groundwork for developing novel cuticle-based strategies for improving the drought tolerance and water use efficiency of crop plants. PMID:22635115

  20. New insight into phase equilibria involving imidazolium bistriflamide ionic liquids and their mixtures with alcohols and water.

    Science.gov (United States)

    Pereiro, Ana B; Deive, Francisco J; Rodríguez, Ana; Ruivo, Diana; Canongia Lopes, José N; Esperança, José M S S; Rebelo, Luís P N

    2010-07-15

    The fluid phase equilibria (liquid-liquid demixing behavior (LLE)) of mixtures of ionic liquids of the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide family, [C(n)mim][NTf(2)], with 2-methylpropanol or n-octanol were investigated. Binary mixtures of [C(4)mim][NTf(2)] + alcohol and [C(6)mim][NTf(2)] + alcohol were compared to pseudobinary mixtures of (0.5[C(2)mim] + 0.5[C(6)mim])[NTf(2)] + alcohol and (0.5[C(2)mim] + 0.5[C(10)mim])[NTf(2)] + alcohol, respectively. Additionally, the presence of water in the studied alcohols or as a third component in the system was analyzed in order to check any possible deviation from the LLE observed for the anhydrous systems. Systems containing small fractions of ionic liquid show similar LLE between the corresponding binary and pseudobinary systems; however, large differences are observed in the presence of water when the IL mass fraction is increased.

  1. Phenols and phenol oxidases are involved in cadmium accumulation in the water plants Nymphoides peltata (Menyanthaceae) and Nymphaeae (Nymphaeaceae).

    Science.gov (United States)

    Lavid, N; Schwartz, A; Lewinsohn, E; Tel-Or, E

    2001-12-01

    This comparative study investigates the mechanism of cadmium accumulation in the semiaquatic plant Nymphoides peltata (Menyanthaceae) and the aquatic plant Nymphaea (Nymphaeaceae). It was conducted as part of an ongoing study of the use of water plants for phytoremediation. Epidermal structures, known as hydropotes, are located on the abaxial epidermis of the leaf laminae of Nymphoides peltata and are shown to contain phenols, peroxidase and polyphenol oxidase activities. When plants are subjected to 50 mg/l of cadmium in the growth medium, these hydropotes accumulate cadmium. Cadmium-induced increases in phenols, peroxidase and polyphenol oxidase activities were determined in plant extracts. Cadmium binding by polymerized phenols was demonstrated in vivo. In comparison with Nymphaeae epidermal glands, N. peltata hydropotes are larger, open, and create bigger crystal, the latter principally composed of calcium and, proportionally, less cadmium. Although both plants showed similar levels of cadmium accumulation, N. peltata was sensitive while Nymphaeae was resistant to this cadmium level. It is suggested that in these water plants the main mechanism for cadmium accumulation is based on the trapping of cadmium crystals by polymerized phenols in specialized epidermal structures and this is due to peroxidase and polyphenol oxidase activities. Nymphaeae, with greater peroxidase activity and more polyphenols, is more resistant to this heavy metal than N. peltata.

  2. Preparation and Supercooling Modification of Salt Hydrate Phase Change Materials Based on CaCl₂·2H₂O/CaCl₂.

    Science.gov (United States)

    Xu, Xiaoxiao; Dong, Zhijun; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi

    2017-06-23

    Salt hydrates have issues of supercooling when they are utilized as phase change materials (PCMs). In this research, a new method was adopted to prepare a salt hydrate PCM (based on a mixture of calcium chloride dihydrate and calcium chloride anhydrous) as a novel PCM system to reduce the supercooling phenomenon existing in CaCl₂·6H₂O. Six samples with different compositions of CaCl₂ were prepared. The relationship between the performance and the proportion of calcium chloride dihydrate (CaCl₂·2H₂O) and calcium chloride anhydrous (CaCl₂) was also investigated. The supercooling degree of the final PCM reduced with the increase in volume of CaCl₂·2H₂O during its preparation. The PCM obtained with 66.21 wt % CaCl₂·2H₂O reduced the supercooling degree by about 96.8%. All six samples, whose ratio of CaCl₂·2H₂O to (CaCl₂ plus CaCl₂·2H₂O) was 0%, 34.03%, 53.82%, 76.56%, 90.74%, and 100% respectively, showed relatively higher enthalpy (greater than 155.29 J/g), and have the possibility to be applied in buildings for thermal energy storage purposes. Hence, CaCl₂·2H₂O plays an important role in reducing supercooling and it can be helpful in adjusting the solidification enthalpy. Thereafter, the influence of adding different percentages of Nano-SiO₂ (0.1 wt %, 0.3 wt %, 0.5 wt %) in reducing the supercooling degree of some PCM samples was investigated. The test results showed that the supercooling of the salt hydrate PCM in Samples 6 and 5 reduced to 0.2 °C and 0.4 °C respectively. Finally, the effect of the different cooling conditions, including frozen storage (-20 °C) and cold storage (5 °C), that were used to prepare the salt hydrate PCM was considered. It was found that both cooling conditions are effective in reducing the supercooling degree of the salt hydrate PCM. With the synergistic action of the two materials, the performance and properties of the newly developed PCM systems were better especially in terms of reducing

  3. Supercool纤维牛仔面料的开发与生产实践%DEVELOPMENT AND PRODUCTION PRACTICE OF SUPERCOOL DENIM

    Institute of Scientific and Technical Information of China (English)

    成海量; 张增强

    2015-01-01

    以48.6 tex赛络纺棉纱、48.6 tex赛络纺竹节纱为经纱,33.3 tex Supercool 吸湿排汗纤维为纬纱开发吸湿排汗牛仔面料。介绍了Supercool纤维的特性, Supercool纤维牛仔面料的规格设计、生产工艺流程,及各工序重要参数的选择和关键生产技术,指出了Supercool纤维牛仔面料开发的基本思路和产品的应用前景。%Taking 48. 6 tex Siro spun yarn plus 48. 6 tex Siro spun slub yarn as warp yarn and 33. 3 tex Supercool, moisture absorption and sweat discharge fiber as weft yarn to develop and porduce the moisture absorption and sweat discharge denim fabric. The article introduced the characteristics of the Supercool fiber, the specification designing of the Supercool Denim, production process, the selection of important parameters in each process and the key to production technology , and pointed out the basic idea of developing the Supercool Denim and the application prospect of the product.

  4. Value of Information and Prospect theory as tools to involve decision-makers in water-related design, operation and planning of water systems

    Science.gov (United States)

    Alfonso, Leonardo

    2013-04-01

    The role of decision-makers is to take the outputs from hydrological and hydraulic analyses and, in some extent, use them as inputs to make decisions that are related to planning, design and operation of water systems. However, the use of these technical analyses is frequently limited, since there are other non-hydrological issues that must be considered, that may end up in very different solutions than those envisaged by the purely technical ones. A possibility to account for the nature of the human decisions under uncertainty is by exploring the use of concepts from decision theory and behavioural economics, such as Value of Information and Prospect Theory and embed them into the methodologies we use in the hydrology practice. Three examples are presented to illustrate these multidisciplinary interactions. The first one, for monitoring network design, uses Value of Information within a methodology to locate water level stations in a complex canal of networks in the Netherlands. The second example, for operation, shows how the Value of Information concept can be used to formulate alternative methods to evaluate flood risk according to the set of options available for decision-making during a flood event. The third example, for planning, uses Prospect Theory concepts to understand how the "losses hurt more than gains feel good" effect can determine the final decision of urbanise or not a flood-prone area. It is demonstrated that decision theory and behavioural economic principles are promising to evaluate the complex decision-making process in water-related issues.

  5. Communication: Towards first principles theory of relaxation in supercooled liquids formulated in terms of cooperative motion.

    Science.gov (United States)

    Freed, Karl F

    2014-10-14

    A general theory of the long time, low temperature dynamics of glass-forming fluids remains elusive despite the almost 20 years since the famous pronouncement by the Nobel Laureate P. W. Anderson, "The deepest and most interesting unsolved problem in solid state theory is probably the theory of the nature of glass and the glass transition" [Science 267, 1615 (1995)]. While recent work indicates that Adam-Gibbs theory (AGT) provides a framework for computing the structural relaxation time of supercooled fluids and for analyzing the properties of the cooperatively rearranging dynamical strings observed in low temperature molecular dynamics simulations, the heuristic nature of AGT has impeded general acceptance due to the lack of a first principles derivation [G. Adam and J. H. Gibbs, J. Chem. Phys. 43, 139 (1965)]. This deficiency is rectified here by a statistical mechanical derivation of AGT that uses transition state theory and the assumption that the transition state is composed of elementary excitations of a string-like form. The strings are assumed to form in equilibrium with the mobile particles in the fluid. Hence, transition state theory requires the strings to be in mutual equilibrium and thus to have the size distribution of a self-assembling system, in accord with the simulations and analyses of Douglas and co-workers. The average relaxation rate is computed as a grand canonical ensemble average over all string sizes, and use of the previously determined relation between configurational entropy and the average cluster size in several model equilibrium self-associating systems produces the AGT expression in a manner enabling further extensions and more fundamental tests of the assumptions.

  6. Cold tolerance and supercooling capacity in overwintering adults of elm leaf beetle Xanthogaleruca luteola (Coleoptera: Chrysomelidae).

    Science.gov (United States)

    Soudi, Sh; Moharramipour, S

    2011-12-01

    Elm leaf beetle, Xanthogaleruca luteola (Muller) is one of the key pests of elm trees all over the world, and survives winter in reproductive diapause in sheltered locations. Seasonal variation of whole body supercooling points (SCPs), LT50 (temperature at which 50% of the test individuals die) and survival rate after exposure to subzero temperatures were determined in field collected adults during October 2008 to May 2009 and October 2009 to May 2010. The SCP of adults decreased significantly from October (median=-13.8°C) to January (median=-20.7°C) in first year, relatively similar results was observed in the second year. The lowest LT50 was observed in overwintering adults collected in January (-16.81°C) in the first year and December (-15.59°C) in the second year. Mortality at -15°C for 24 h was >70% in early autumn in both years whereas it decreased to lower than 45% in early winter, the highest mortality (100%) was observed in adults collected in May in both years. Cold acclimated adults (30 d, 5°C) in November 2008 exhibited significantly higher SCP (-12.21±0.64°C) than nonacclimated adults (-15.57±1.35°C). A 30-d exposure to 5°C caused >20% mortality in November, while <9% mortality was observed in adults collected in December and January 2008. Overwintering adults died upon freezing and the lower lethal temperatures were within the range of SCP, indicating that X. luteola is a freeze intolerant insect.

  7. Stem carbohydrate dynamics and expression of genes involved in fructan accumulation and remobilization during grain growth in wheat (Triticum aestivum L.) genotypes with contrasting tolerance to water stress

    Science.gov (United States)

    Yáñez, Alejandra; Tapia, Gerardo; Guerra, Fernando

    2017-01-01

    The genetic and physiological mechanisms underlying the relationship between water-soluble carbohydrates (WSC) and water stress tolerance are scarcely known. This study aimed to evaluate the main WSC in stems, and the expression of genes involved in fructan metabolism in wheat genotypes growing in a glasshouse with water stress (WS; 50% field capacity from heading) and full irrigation (FI; 100% field capacity). Eight wheat genotypes (five tolerant and three susceptible to water stress) were evaluated initially (experiment 1) and the two most contrasting genotypes in terms of WSC accumulation were evaluated in a subsequent experiment (experiment 2). Maximum accumulation of WSC occurred 10–20 days after anthesis. Under WS, the stress-tolerant genotype exhibited higher concentrations of WSC, glucose, fructose and fructan in the stems, compared to FI. In addition, the stress-tolerant genotype exhibited higher up-regulation of the fructan 1-fructosyltransferase B (1-FFTB) and fructan 1-exohydrolase w2 (1-FEHw2) genes, whereas the susceptible cultivar presented an up-regulation of the fructan 6-fructosyltransferase (6-SFT) and fructan 1-exohydrolase w3 (1-FEHw3) genes. Our results indicated clear differences in the pattern of WSC accumulation and the expression of genes regulating fructan metabolism between the tolerant and susceptible genotypes under WS. PMID:28552955

  8. Supercooling of the disordered vortex lattice in Bi(2)Sr(2)CaCu(2)O(8+delta)

    Science.gov (United States)

    van Der Beek CJ; Colson; Indenbom; Konczykowski

    2000-05-01

    Time-resolved local induction measurements near the vortex lattice order-disorder transition in optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta) crystals show that the high-field, disordered phase can be quenched to fields as low as half the transition field. Over an important range of fields, the electrodynamical behavior of the vortex system is governed by the coexistence of ordered and disordered vortex phases in the sample. We interpret the results as supercooling of the high-field phase and the possible first-order nature of the order-disorder transition at the "second magnetization peak."

  9. Structural crossover in a supercooled metallic liquid and the link to a liquid-to-liquid phase transition

    Science.gov (United States)

    Lan, S.; Blodgett, M.; Kelton, K. F.; Ma, J. L.; Fan, J.; Wang, X.-L.

    2016-05-01

    Time-resolved synchrotron measurements were carried out to capture the structure evolution of an electrostatically levitated metallic-glass-forming liquid during free cooling. The experimental data shows a crossover in the liquid structure at ˜1000 K, about 115 K below the melting temperature and 150 K above the crystallization temperature. The structure change is characterized by a dramatic growth in the extended-range order below the crossover temperature. Molecular dynamics simulations have identified that the growth of the extended-range order was due to an increased correlation between solute atoms. These results provide structural evidence for a liquid-to-liquid-phase-transition in the supercooled metallic liquid.

  10. NASA/FAA/NCAR Supercooled Large Droplet Icing Flight Research: Summary of Winter 1996-1997 Flight Operations

    Science.gov (United States)

    Miller, Dean; Ratvasky, Thomas; Bernstein, Ben; McDonough, Frank; Strapp, J. Walter

    1998-01-01

    During the winter of 1996-1997, a flight research program was conducted at the NASA-Lewis Research Center to study the characteristics of Supercooled Large Droplets (SLD) within the Great Lakes region. This flight program was a joint effort between the National Aeronautics and Space Administration (NASA), the National Center for Atmospheric Research (NCAR), and the Federal Aviation Administration (FAA). Based on weather forecasts and real-time in-flight guidance provided by NCAR, the NASA-Lewis Icing Research Aircraft was flown to locations where conditions were believed to be conducive to the formation of Supercooled Large Droplets aloft. Onboard instrumentation was then used to record meteorological, ice accretion, and aero-performance characteristics encountered during the flight. A total of 29 icing research flights were conducted, during which "conventional" small droplet icing, SLD, and mixed phase conditions were encountered aloft. This paper will describe how flight operations were conducted, provide an operational summary of the flights, present selected experimental results from one typical research flight, and conclude with practical "lessons learned" from this first year of operation.

  11. Supercooling capacity and cold hardiness of the adults of the sycamore lace bug, corythucha ciliata (Hemiptera:Tingidae).

    Science.gov (United States)

    Ju, Rui-Ting; Wang, Feng; Xiao, Yu-Yu; Li, Bo

    2010-01-01

    Supercooling point (SCP) of female adults of Corythucha ciliata was significantly lower than that of male adults, with an average being -11.49 degrees C and -9.54 degrees C, respectively. Low temperature survival of adults of different ages indicated that there were differences in cold survival ability among age groups of adults. Nonlinear regression analysis found that the response of C. ciliata adults to exposure time under different low temperature regimes (above -5 degrees C) was best fitted by a logistic equation. Both low temperature and exposure time had significant effects on mortality of adults. Temperatures above 5 degrees C did not prevent C. ciliata adults from surviving. C. ciliata was shown to be a freeze-intolerant but chill-tolerant insect. C. ciliata could tolerate subzero temperatures by supercooling. Temperature around -8 degres C is a critical point for successful overwintering of C. ciliata adults, which can establish in the whole areas where Platanus trees are planted in China.

  12. Dynamics of supercooled liquid and plastic crystalline ethanol: Dielectric relaxation and AC nanocalorimetry distinguish structural α- and Debye relaxation processes

    Science.gov (United States)

    Chua, Y. Z.; Young-Gonzales, A. R.; Richert, R.; Ediger, M. D.; Schick, C.

    2017-07-01

    Physical vapor deposition has been used to prepare glasses of ethanol. Upon heating, the glasses transformed into the supercooled liquid phase and then crystallized into the plastic crystal phase. The dynamic glass transition of the supercooled liquid is successfully measured by AC nanocalorimetry, and preliminary results for the plastic crystal are obtained. The frequency dependences of these dynamic glass transitions observed by AC nanocalorimetry are in disagreement with conclusions from previously published dielectric spectra of ethanol. Existing dielectric loss spectra have been carefully re-evaluated considering a Debye peak, which is a typical feature in the dielectric loss spectra of monohydroxy alcohols. The re-evaluated dielectric fits reveal a prominent dielectric Debye peak, a smaller and asymmetrically broadened peak, which is identified as the signature of the structural α-relaxation and a Johari-Goldstein secondary relaxation process. This new assignment of the dielectric processes is supported by the observation that the AC nanocalorimetry dynamic glass transition temperature, Tα, coincides with the dielectric structural α-relaxation process rather than the Debye process. The combined results from dielectric spectroscopy and AC nanocalorimetry on the plastic crystal of ethanol suggest the occurrence of a Debye process also in the plastic crystal phase.

  13. Second Inflection Point of the Surface Tension of Water

    Science.gov (United States)

    Kalova, Jana; Mares, Radim

    2012-06-01

    The theme of a second inflection point of the temperature dependence of the surface tension of water remains a subject of controversy. Using data above 273 K, it is difficult to get a proof of existence of the second inflection point, because of experimental uncertainties. Data for the surface tension of supercooled water and results of a molecular dynamics study were included into the exploration of existence of an inflection point. A new term was included into the IAPWS equation to describe the surface tension in the supercooled water region. The new equation describes the surface tension values of ordinary water between 228 K and 647 K and leads to the inflection point value at a temperature of about 1.5 °C.

  14. Temperature-Independent Nuclear Quantum Effects on the Structure of Water

    Science.gov (United States)

    Kim, Kyung Hwan; Pathak, Harshad; Späh, Alexander; Perakis, Fivos; Mariedahl, Daniel; Sellberg, Jonas A.; Katayama, Tetsuo; Harada, Yoshihisa; Ogasawara, Hirohito; Pettersson, Lars G. M.; Nilsson, Anders

    2017-08-01

    Nuclear quantum effects (NQEs) have a significant influence on the hydrogen bonds in water and aqueous solutions and have thus been the topic of extensive studies. However, the microscopic origin and the corresponding temperature dependence of NQEs have been elusive and still remain the subject of ongoing discussion. Previous x-ray scattering investigations indicate that NQEs on the structure of water exhibit significant temperature dependence [Phys. Rev. Lett. 94, 047801 (2005), 10.1103/PhysRevLett.94.047801]. Here, by performing wide-angle x-ray scattering of H2O and D2O droplets at temperatures from 275 K down to 240 K, we determine the temperature dependence of NQEs on the structure of water down to the deeply supercooled regime. The data reveal that the magnitude of NQEs on the structure of water is temperature independent, as the structure factor of D2O is similar to H2O if the temperature is shifted by a constant 5 K, valid from ambient conditions to the deeply supercooled regime. Analysis of the accelerated growth of tetrahedral structures in supercooled H2O and D2O also shows similar behavior with a clear 5 K shift. The results indicate a constant compensation between NQEs delocalizing the proton in the librational motion away from the bond and in the OH stretch vibrational modes along the bond. This is consistent with the fact that only the vibrational ground state is populated at ambient and supercooled conditions.

  15. Velocity and pattern of ice propagation and deep supercooling in woody stems of Castanea sativa, Morus nigra and Quercus robur measured by IDTA.

    Science.gov (United States)

    Neuner, Gilbert; Xu, Bingcheng; Hacker, Juergen

    2010-08-01

    Infrared differential thermal analysis (IDTA) was used to monitor the velocity and pattern of ice propagation and deep supercooling of xylem parenchyma cells (XPCs) during freezing of stems of Castanea sativa L., Morus nigra L. and Quercus robur L. that exhibit a macro- and ring-porous xylem. Measurements were conducted on the surface of cross- and longitudinal stem sections. During high-temperature freezing exotherms (HTEs; -2.8 to -9.4°C), initial freezing was mainly observed in the youngest year ring of the sapwood (94%), but occasionally elsewhere (older year rings: 4%; bark: 2%). Initially, ice propagated rapidly in the largest xylem conduits. This resulted in a distinct freezing pattern of concentric circles in C. sativa and M. nigra. During HTEs, supercooling of XPCs became visible in Q. robur stems, but not in the other species that have narrower pith rays. Intracellular freezing of supercooled XPCs of Q. robur became visible by IDTA during low-temperature freezing exotherms (<-17.4 °C). Infrared differential thermal analysis revealed the progress and the two-dimensional pattern of XPC freezing. XPCs did not freeze at once, but rather small cell groups appeared to freeze at random anywhere in the xylem. By IDTA, ice propagation and deep supercooling in stems can be monitored at meaningful spatial and temporal resolutions.

  16. Monitoring the Temporal Expression of Genes Involved in Ochratoxin A Production of Aspergillus carbonarius under the Influence of Temperature and Water Activity

    Directory of Open Access Journals (Sweden)

    Iliada K. Lappa

    2017-09-01

    Full Text Available The objective of this study was to investigate the effect of environmental factors, namely temperature and water activity, on genes involved in the regulation of ochratoxin A (OTA production over time. For this purpose, the previously characterized toxigenic Aspergillus carbonarius Ac29 isolate from Greek vineyards and the A. carbonarius ITEM 5010 reference strain were subjected to combined temperature and water activity (aw treatments to study OTA production and relative gene expression. The fungal isolates were grown on a synthetic grape juice liquid medium (SGM under different temperature (20 °C, 25 °C and 30 °C and aw (0.94 and 0.98 regimes. The expression of the AcOTApks, AcOTAnrps, and laeA OTA related genes was investigated using real time PCR. Gene expression was monitored at the same time points, along with fungal biomass and OTA accumulation at three, six and nine days of incubation. In gene expression analysis, stimulation of the biosynthetic genes was observed a few days before any toxin could be detected. This fact may underline a possible early indicator of potential toxin contamination of grapes. However, the transcript levels varied with respect to the different combinations of ecophysiological conditions and time, highlighting a complex regulation of OTA related gene expression of A. carbonarius in the specific medium.

  17. A community trial involving religious leaders to improve water preparation hygiene as part of diarrheal disease prevention in South kalimantan, indonesia.

    Science.gov (United States)

    Prihartono, N; Damayanti, R; Adisasmita, A; Tarigan, L

    1993-01-01

    In an earlier study we found that there is a habit of mixing boiled and unboiled water to prepare drinks, particularly cold tea, in South Kalimantan, Indonesia. Ulamas (Islamic religious leaders) have a very influential role in that community. This study was designed to implement and evaluate a health educational campaign using local ulamas. Three study communities were selected. The first intervention area received education through Al Quran (Koranic) reading clubs. In the second area the intervention was implemented by home visits as well as by Al Quran reading clubs, since participation in Al Quran reading clubs was low. The third area served as the control. A message and intervention development was designed by the ulamas and the investigators using sarasehan (ulamas' meeting). A positive impact on knowledge and practices of drinking water preparation was observed in the first area where the community members were active participants in the Al Quran reading club. Involving ulamas in a health education campaign was indicated to be effective in changing knowledge and practices.

  18. Water-Soluble Compounds from Lentinula edodes Influencing the HMG-CoA Reductase Activity and the Expression of Genes Involved in the Cholesterol Metabolism.

    Science.gov (United States)

    Gil-Ramírez, Alicia; Caz, Víctor; Smiderle, Fhernanda R; Martin-Hernandez, Roberto; Largo, Carlota; Tabernero, María; Marín, Francisco R; Iacomini, Marcello; Reglero, Guillermo; Soler-Rivas, Cristina

    2016-03-09

    A water extract from Lentinula edodes (LWE) showed HMG-CoA reductase inhibitory activity but contained no statins. NMR indicated the presence of water-soluble α- and β-glucans and fucomannogalactans. Fractions containing derivatives of these polysaccharides with molecular weight down to approximately 1 kDa still retained their inhibitory activity. Once digested LWE was applied to Caco2 in transport experiments, no significant effect was noticed on the modulation of cholesterol-related gene expression. But, when the lower compartment of the Caco2 monolayer was applied to HepG2, some genes were modulated (after 24 h). LWE was also administrated to normo- and hypercholesterolemic mice, and no significant lowering of serum cholesterol levels was observed; but reduction of triglycerides in liver was observed. However, LWE supplementation modulated the transcriptional profile of some genes involved in the cholesterol metabolism similarly to simvastatin, suggesting that it could hold potential as a hypolipidemic/hypocholesterolemic extract, although further dose-dependent studies should be carried out.

  19. Water

    Science.gov (United States)

    Leopold, Luna Bergere; Baldwin, Helene L.

    1962-01-01

    What do you use water for?If someone asked you this question you would probably think right away of water for drinking. Then you would think of water for bathing, brushing teeth, flushing the toilet. Your list would get longer as you thought of water for cooking, washing the dishes, running the garbage grinder. Water for lawn watering, for play pools, for swimming pools, for washing the car and the dog. Water for washing machines and for air conditioning. You can hardly do without water for fun and pleasure—water for swimming, boating, fishing, water-skiing, and skin diving. In school or the public library, you need water to wash your hands, or to have a drink. If your home or school bursts into flames, quantities of water are needed to put it out.In fact, life to Americans is unthinkable without large supplies of fresh, clean water. If you give the matter a little thought, you will realize that people in many countries, even in our own, may suffer from disease and dirt simply because their homes are not equipped with running water. Imagine your own town if for some reason - an explosion, perhaps - water service were cut off for a week or several weeks. You would have to drive or walk to a neighboring town and bring water back in pails. Certainly if people had to carry water themselves they might not be inclined to bathe very often; washing clothes would be a real chore.Nothing can live without water. The earth is covered by water over three-fourths of its surface - water as a liquid in rivers, lakes and oceans, and water as ice and snow on the tops of high mountains and in the polar regions. Only one-quarter of our bodies is bone and muscle; the other three-fourths is made of water. We need water to live, and so do plants and animals. People and animals can live a long time without food, but without water they die in a few days. Without water, everything would die, and the world would turn into a huge desert.

  20. Volumetric properties of magnesium silicate glasses and supercooled liquid at high pressure by X-ray microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Lesher, Charles E.; Wang, Yanbin; Gaudio, Sarah; Clark, Alisha; Nishiyama, Nori; Rivers, Mark; (UCD); (UC)

    2009-06-01

    The volumetric properties of silicate glasses and supercooled liquid are examined at high pressures and temperatures using X-ray computed tomography (CT) and absorption. The high pressure X-ray microtomography (HPXMT) system at the Advanced Photon Source, Argonne National Laboratory (GeoSoilEnvironCARS 13-BM-D beamline) consists of two opposing anvils compressed within an X-ray-transparent containment ring supported by thrust bearings and loaded using a 250-ton hydraulic press. This system permits the pressure cell to rotate under the load, while collecting radiographs through at least 180{sup o} of rotation. The 13-BM-D beamline permits convenient switching between monochromatic radiation required for radiography and polychromatic radiation for pressure determination by energy dispersive diffraction. We report initial results on several refractory magnesium silicate glasses synthesized by levitation laser heating. Volume changes during room temperature compression of Mg-silicate glasses with 33 mol% and 38 mol% SiO2 up to 11.5 GPa give an isothermal bulk moduli of 93--100 GPa for a K' of 1. These values are consistent with ultrasonic measurements of more silica-rich glasses. The volumetric properties of amorphous MgSiO{sub 3} at 2 GPa were examined during annealing up to 1000 C. We consider the consequences of heating through the glass transition and the implications for thermal expansivity of supercooled liquids at high pressure. Our results illustrate the capabilities of HPXMT for studies of refractory glasses and liquids at high pressure and offer strategies for future studies of liquid densities within the melting interval for magmas in planet interiors.

  1. Parental Involvement

    OpenAIRE

    Ezra S Simon

    2008-01-01

    This study was conducted in Ghana to investigate, (1) factors that predict parental involvement, (2) the relationship between parental home and school involvement and the educational achievement of adolescents, (3) the relationship between parental authoritativeness and the educational achievement of adolescent students, (4) parental involvement serving as a mediator between their authoritativeness and the educational achievement of the students, and (5) whether parental involvement decreases...

  2. Perspective on the structure of liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, A., E-mail: nilsson@slac.stanford.edu [Stanford Synchrotron Radiation Lightsource, P.O. Box 20450, Stanford, CA 94309 (United States); Department of Physics, AlbaNova University Center, Stockholm University, S-106 91 Stockholm (Sweden); Pettersson, L.G.M. [Department of Physics, AlbaNova University Center, Stockholm University, S-106 91 Stockholm (Sweden)

    2011-11-07

    Graphical abstract: Liquid water can be described in a fluctuating inhomogeneous picture with two local structural motifs that are spatially separated. At ambient temperatures most molecules favor a closer packing than tetrahedral, with strongly distorted hydrogen bonds giving higher density (yellow), which allows the quantized librational modes to be excited and contribute to the entropy, but with enthalpically favored tetrahedrally bonded water patches appearing as fluctuations (blue), i.e. a competition between entropy and enthalpy. Upon cooling water the amount of molecules participating in tetrahedral structures and the size of the tetrahedral patches increase. Highlights: Black-Right-Pointing-Pointer Two components maximizing either enthalpy (tetrahedral, low-density) or entropy (non-specific H-bonding, higher density). Black-Right-Pointing-Pointer Interconvert discontinuously and ratio depends on temperature. Black-Right-Pointing-Pointer Density fluctuations on 1 nm length scale. Black-Right-Pointing-Pointer Increasing size in supercooled region. Black-Right-Pointing-Pointer Connection to Widom line and 2nd critical point. - Abstract: We present a picture that combines discussions regarding the thermodynamic anomalies in ambient and supercooled water with recent interpretations of X-ray spectroscopy and scattering data of water in the ambient regime. At ambient temperatures most molecules favor a closer packing than tetrahedral, with strongly distorted hydrogen bonds, which allows the quantized librational modes to be excited and contribute to the entropy, but with enthalpically favored tetrahedrally bonded water patches appearing as fluctuations, i.e. a competition between entropy and enthalpy. Upon cooling water the amount of molecules participating in tetrahedral structures and the size of the tetrahedral patches increase. The two local structures are connected to the liquid-liquid critical point hypothesis in supercooled water corresponding to high

  3. Water

    Science.gov (United States)

    ... Lead Poisoning Prevention Training Center (HHLPPTC) Training Tracks Water Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir For information about lead in water in Flint, MI, please visit http://www.phe. ...

  4. Involvement of mitogen-activated protein kinase pathways in expression of the water channel protein aquaporin-4 after ischemia in rat cortical astrocytes.

    Science.gov (United States)

    Nito, Chikako; Kamada, Hiroshi; Endo, Hidenori; Narasimhan, Purnima; Lee, Yong-Sun; Chan, Pak H

    2012-09-20

    Brain edema after ischemic brain injury is a key determinant of morbidity and mortality. Aquaporin-4 (AQP4) plays an important role in water transport in the central nervous system and is highly expressed in brain astrocytes. However, the AQP4 regulatory mechanisms are poorly understood. In this study, we investigated whether mitogen-activated protein kinases (MAPKs), which are involved in changes in osmolality, might mediate AQP4 expression in models of rat cortical astrocytes after ischemia. Increased levels of AQP4 in primary cultured astrocytes subjected to oxygen-glucose deprivation (OGD) and 2 h of reoxygenation were observed, after which they immediately decreased at 0 h of reoxygenation. Astrocytes exposed to OGD injury had significantly increased phosphorylation of three kinds of MAPKs. Treatment with SB203580, a selective p38 MAPK inhibitor, or SP600125, a selective c-Jun N-terminal kinase inhibitor, significantly attenuated the return of AQP4 to its normal level, and SB203580, but not SP600125, significantly decreased cell death. In an in vivo study, AQP4 expression was upregulated 1-3 days after reperfusion, which was consistent with the time course of p38 phosphorylation and activation, and decreased by the p38 inhibition after transient middle cerebral artery occlusion (MCAO). These results suggest that p38 MAPK may regulate AQP4 expression in cortical astrocytes after ischemic injury.

  5. Simultaneous Synchrotron WAXD and Fast Scanning (Chip) Calorimetry: On the (Isothermal) Crystallization of HDPE and PA11 at High Supercoolings and Cooling Rates up to 200 °C s(-1).

    Science.gov (United States)

    Baeten, Dorien; Mathot, Vincent B F; Pijpers, Thijs F J; Verkinderen, Olivier; Portale, Giuseppe; Van Puyvelde, Peter; Goderis, Bart

    2015-06-01

    An experimental setup, making use of a Flash DSC 1 prototype, is presented in which materials can be studied simultaneously by fast scanning calorimetry (FSC) and synchrotron wide angle X-ray diffraction (WAXD). Accumulation of multiple, identical measurements results in high quality, millisecond WAXD patterns. Patterns at every degree during the crystallization and melting of high density polyethylene at FSC typical scanning rates from 20 up to 200 °C s(-1) are discussed in terms of the temperature and scanning rate dependent material crystallinities and crystal densities. Interestingly, the combined approach reveals FSC thermal lag issues, for which can be corrected. For polyamide 11, isothermal solidification at high supercooling yields a mesomorphic phase in less than a second, whereas at very low supercooling crystals are obtained. At intermediate supercooling, mixtures of mesomorphic and crystalline material are generated at a ratio proportional to the supercooling. This ratio is constant over the isothermal solidification time.

  6. Modelling and interpreting the isotopic composition of water vapour in convective updrafts

    Directory of Open Access Journals (Sweden)

    M. Bolot

    2013-08-01

    Full Text Available The isotopic compositions of water vapour and its condensates have long been used as tracers of the global hydrological cycle, but may also be useful for understanding processes within individual convective clouds. We review here the representation of processes that alter water isotopic compositions during processing of air in convective updrafts and present a unified model for water vapour isotopic evolution within undiluted deep convective cores, with a special focus on the out-of-equilibrium conditions of mixed-phase zones where metastable liquid water and ice coexist. We use our model to show that a combination of water isotopologue measurements can constrain critical convective parameters, including degree of supersaturation, supercooled water content and glaciation temperature. Important isotopic processes in updrafts include kinetic effects that are a consequence of diffusive growth or decay of cloud particles within a supersaturated or subsaturated environment; isotopic re-equilibration between vapour and supercooled droplets, which buffers isotopic distillation; and differing mechanisms of glaciation (droplet freezing vs. the Wegener–Bergeron–Findeisen process. As all of these processes are related to updraft strength, particle size distribution and the retention of supercooled water, isotopic measurements can serve as a probe of in-cloud conditions of importance to convective processes. We study the sensitivity of the profile of water vapour isotopic composition to differing model assumptions and show how measurements of isotopic composition at cloud base and cloud top alone may be sufficient to retrieve key cloud parameters.

  7. Transitions between mesophases involving cubic phases in the surfactant-water systems. Epitaxial relations and their consequences in a geometrical framework

    Science.gov (United States)

    Clerc, M.; Levelut, A. M.; Sadoc, J. F.

    1991-10-01

    In order to approach the fascinating structure of the cubic mesophases, we study phase transitions involving them and another mesophases with simpler structures. In the first part, we give some results obtained in the C_{12}EO_6/water binary system, that exhibits the most frequent case of bicontinuous cubic mesophase, with space group Ia3d, and two transitions toward the hexagonal and lamellar mesophases. X-ray scattering experiments and some optical observations in polarized light are presented for oriented single-domains of the mesophases. In the second part, we propose some topological arguments to explain the transformations involved at these two transitions and propose some possible fluctuations associated with them. les phases cubiques dans les systèmes eau/savon sont un exemple tout à fait remarquable d'organisation moléculaire entre liquides. Nous présentons ici une étude de transitions de phases entre elles et d'autres phases de structure beaucoup moins complexe, en montrant comment la structure cubique peut se déduire de celle des autres. Dans la première partie, nous présentons les résultats obtenus pour le système modèle C_{12}EO_6/eau, qui offre le cas le plus fréquent de phase cubique bicontinue, de groupe d'espace Ia3d, ainsi que deux transitions vers les phases hexagonale et lamellaire. Des clichés de diffraction des rayons X aux petits angles ont été obtenus pour des échantillons orientés de ces phases, mettant en particulier en évidence les fluctuations des structures observées, par la présence de “diffusions diffuses" entre les réflexions de Bragg. Dans la seconde partie, nous exposons une analyse détaillée des changements de topologie intervenant lors de ces deux transitions, puis discutons des fluctuations pouvant leur être associées, à la lumière des observations précédentes.

  8. Workability of the supercooled liquid in the Zr{sub 65}Al{sub 10}Ni{sub 10}Cu{sub 15} bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Y.; Shibata, T.; Inoue, A.; Masumoto, T. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

    1997-12-19

    The workability of the supercooled liquid in metallic glass has been examined through the extrusion of a Zr{sub 6.5}Al{sub 10}Ni{sub 10}Cu{sub 15} at.% bulk glassy alloy with a wide supercooled liquid region. The metallic glass exhibited superplastic-like deformation behavior at high strain rates, resulting in an excellent workability. The working throughout a wide range of extrusion conditions was compatible with retaining the glass phase and the original strength. The extrusion maps and the expression between extrusion temperature, pressure and ram-speed have been established. Moreover, the features of working such as the Barus effect and the advantage of a small stepwise increase in strain rate have been revealed.

  9. Water

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2010-08-01

    Full Text Available Water scarcity is without a doubt on of the greatest threats to the human species and has all the potential to destabilise world peace. Falling water tables are a new phenomenon. Up until the development of steam and electric motors, deep groudwater...

  10. The protective effect of rapid cold-hardening develops more quickly in frozen versus supercooled larvae of the Antarctic midge, Belgica antarctica.

    Science.gov (United States)

    Kawarasaki, Yuta; Teets, Nicholas M; Denlinger, David L; Lee, Richard E

    2013-10-15

    During the austral summer, larvae of the terrestrial midge Belgica antarctica (Diptera: Chironomidae) experience highly variable and often unpredictable thermal conditions. In addition to remaining freeze tolerant year-round, larvae are capable of swiftly increasing their cold tolerance through the rapid cold-hardening (RCH) response. The present study compared the induction of RCH in frozen versus supercooled larvae. At the same induction temperature, RCH occurred more rapidly and conferred a greater level of cryoprotection in frozen versus supercooled larvae. Furthermore, RCH in frozen larvae could be induced at temperatures as low as -12°C, which is the lowest temperature reported to induce RCH. Remarkably, as little as 15 min at -5°C significantly enhanced larval cold tolerance. Not only is protection from RCH acquired swiftly, but it is also quickly lost after thawing for 2 h at 2°C. Because the primary difference between frozen and supercooled larvae is cellular dehydration caused by freeze concentration of body fluids, we also compared the effects of acclimation in dehydrated versus frozen larvae. Because slow dehydration without chilling significantly increased larval survival to a subsequent cold exposure, we hypothesize that cellular dehydration caused by freeze concentration promotes the rapid acquisition of cold tolerance in frozen larvae.

  11. Some thermodynamical aspects of protein hydration water

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Mallamace, Domenico [Dipartimento SASTAS, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Vasi, Cirino [CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Chen, Sow-Hsin [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-06-07

    We study by means of nuclear magnetic resonance the self-diffusion of protein hydration water at different hydration levels across a large temperature range that includes the deeply supercooled regime. Starting with a single hydration shell (h = 0.3), we consider different hydrations up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein hydration water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the hydration level and (ii) the first hydration shell remains liquid at all hydrations, even at the lowest temperature.

  12. Patterns of variation in glycogen, free glucose and lactate in organs of supercooled hatchling painted turtles (Chrysemys picta).

    Science.gov (United States)

    Packard, Mary J; Packard, Gary C

    2005-08-01

    Hatchling painted turtles (Chrysemys picta) typically spend their first winter of life in a shallow, subterranean hibernaculum (the natal nest), where they may be exposed for extended periods to ice and cold. The key to their survival seems to be to avoid freezing and to sustain a state of supercooling. As temperature declines below 0 degrees C, however, the heart of an unfrozen turtle beats progressively slower, the diminished perfusion of peripheral tissues with blood induces a functional hypoxia, and anaerobic glycolysis assumes ever greater importance as a source of ATP. We hypothesized that diminished circulatory function in supercooled turtles also reduces the delivery of metabolic substrates to peripheral tissues from central stores in the liver, so that the tissues depend increasingly on endogenous stores to fuel their metabolism. We discovered in the current investigation that part of the glycogen reserve in hearts and brains of hatchlings is mobilized during the first 10 days of exposure to -6 degrees C but that glucose from hepatic glycogen supports metabolism of the organs thereafter. Hatchlings that were held at -6 degrees C for 10 days and then at +3 degrees C for another 10 days were able to reconstitute some of the reserve of glycogen in heart and liver but not the glycogen reserve in brain. Patterns of accumulation of lactate in individual organs were very similar to those reported for whole animals in a companion study, and point to a high degree of reliance on anaerobic metabolism at -6 degrees C and to a lesser degree of reliance on anaerobiosis at higher subzero temperatures. Lactate had returned to baseline levels in organs of animals that were held for 10 days at -6 degrees C and for another 10 days at +3 degrees C, but free glucose remained elevated. Indeed, carbohydrate metabolism probably does not return to the pre-exposure state in any of the major organs until well after the exposure to subzero temperatures has ended, circulatory

  13. Phase transitions and dynamics of bulk and interfacial water

    Energy Technology Data Exchange (ETDEWEB)

    Franzese, G; Hernando-Martinez, A [Departament de Fisica Fonamental, Universitat de Barcelona, Diagonal 647, Barcelona 08028 (Spain); Kumar, P [Center for Studies in Physics and Biology, Rockefeller University, 1230 York Avenue, New York, NY 10021 (United States); Mazza, M G; Stokely, K; Strekalova, E G; Stanley, H E [Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215 (United States); De los Santos, F, E-mail: gfranzese@ub.ed [Departamento de Electromagnetismo y Fisica de la Materia, Universidad de Granada, Fuentenueva s/n, 18071 Granada (Spain)

    2010-07-21

    New experiments on water at the surface of proteins at very low temperature display intriguing dynamic behaviors. The extreme conditions of these experiments make it difficult to explore the wide range of thermodynamic state points needed to offer a suitable interpretation. Detailed simulations suffer from the same problem, where equilibration times at low temperature become extremely long. We show how Monte Carlo simulations and mean field calculations using a tractable model of water help interpret the experimental results. Here we summarize the results for bulk water and investigate the thermodynamic and dynamic properties of supercooled water at an interface.

  14. Water

    Directory of Open Access Journals (Sweden)

    E. Sanmuga Priya

    2017-05-01

    Full Text Available Phytoremediation through aquatic macrophytes treatment system (AMATS for the removal of pollutants and contaminants from various natural sources is a well established environmental protection technique. Water hyacinth (Eichhornia crassipes, a worst invasive aquatic weed has been utilised for various research activities over the last few decades. The biosorption capacity of the water hyacinth in minimising various contaminants present in the industrial wastewater is well studied. The present review quotes the literatures related to the biosorption capacity of the water hyacinth in reducing the concentration of dyestuffs, heavy metals and minimising certain other physiochemical parameters like TSS (total suspended solids, TDS (total dissolved solids, COD (chemical oxygen demand and BOD (biological oxygen demand in textile wastewater. Sorption kinetics through various models, factors influencing the biosorption capacity, and role of physical and chemical modifications in the water hyacinth are also discussed.

  15. The limit of metastability of water under tension: theories and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Herbert, Eric; Caupin, Frederic [Laboratoire de Physique Statistique de l' Ecole Normale Superieure, associe aux Universites Paris 6 et Paris 7 et au CNRS, 24 rue Lhomond 75231 Paris Cedex 05 (France)

    2005-11-16

    Two scenarios are proposed for explaining the thermodynamic anomalies of supercooled water, but they cannot be directly tested in this region because of the onset of homogeneous crystallization. They also give two distinct temperature dependences of the limit of metastability of water stretched beyond its boiling curve: either monotonic, as in simple liquids, or exhibiting a minimum. Therefore cavitation experiments could allow one to distinguish between the competing pictures. We review previous experiments and describe our preliminary results.

  16. Growth of mixed K2(Ni,Co)(SO4)2·6H2O crystals under stationary conditions of supercooling and forced convection of the aqueous solution

    Science.gov (United States)

    Masalov, Vladimir M.; Vasilyeva, Natalia A.; Manomenova, Vera L.; Zhokhov, Andrei A.; Rudneva, Elena B.; Voloshin, Alexey E.; Emelchenko, Gennadi A.

    2017-10-01

    The technique and the scheme of the system for growing single crystals, including complex mixed composition, under stationary conditions of supercooling and forced convection of aqueous solution were described. Solubility in water of various compositions of K2CoxNi1-x(SO4)2·6H2O (KCNSH) and the dependence of Co content in the KCNSH crystal of Co concentration in the saline part of aqueous solutions of KCNSH have been measured in the temperature range of 30-70 °C. It was found that the growth sectors {0 0 1} and {1 1 0} differ in Ni and Co contents. The Ni/Co ratio is dependent on the value of solution supersaturation. The optical transmission spectra of crystals grown showed high transmittance in the UV region of the spectrum and the almost complete absorption of light in the visible spectrum. It is concluded that the crystals grown can be used as efficient UV filters.

  17. Community involvement

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1979-09-01

    Full Text Available Community involvement is the main theme of Health Year. Governments have a responsibility for the health of their people, and in this country under the present 3-tier system of government, the responsibility for the rendering of health services is divided between central, provincial and local government. However, under our democratic system, all people have the right to, and it is indeed their duty, to participate individually and collectively in the planning and implementation of services to meet their health needs. Ultimately, through involvement of individuals, families and communities, greater self-reliance is achieved leading to greater responsibility being assumed by people for their own health.

  18. The Influence of Constitutional Supercooling on the Distribution of Te-particles in Melt-Grown CZT

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Alvine, Kyle J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bliss, Mary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stave, Jean A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-09-03

    A section of a vertical gradient freeze Cd0.9Zn0.1Te boule approximately 2100-mm3 with a planar area of 300-mm2 was prepared and examined using transmitted IR microscopy at various magnifications to determine the three-dimensional spatial and size distributions of Te-particles over large longitudinal and radial length scales. Te-particle density distributions were determined as a function of longitudinal and radial positions in these strips and exhibited a multi-modal lognormal size density distribution that indicated a slight preference for increasing size with longitudinal growth time, while showing a pronounced cellular network structure. Higher magnification images revealed a typical Rayleigh-instability pearl string morphology with large and small satellite droplets. This study includes solidification experiments in small crucibles of 30:70 mixtures of Cd:Te performed over a wide range of cooling rates that clearly demonstrated a growth instability with Te-particle capture that is suggested to be responsible for one of the peaks in the size distribution using size discrimination visualization. The results are discussed with regard to a manifold Te-particle genesis history as Te-particle direct capture from melt-solid growth instabilities due to constitutional supercooling and as Te-particle formation from the breakup of Te-ribbons via a Rayleigh-Plateau instability.

  19. Effect of total and pair configurational entropy in determining dynamics of supercooled liquids over a range of densities

    Science.gov (United States)

    Banerjee, Atreyee; Nandi, Manoj Kumar; Sastry, Srikanth; Bhattacharyya, Sarika Maitra

    2016-07-01

    In this paper, we present a study of supercooled liquids interacting with the Lennard Jones potential and the corresponding purely repulsive (Weeks-Chandler-Andersen) potential, over a range of densities and temperatures, in order to understand the origin of their different dynamics in spite of their structures being similar. Using the configurational entropy as the thermodynamic marker via the Adam Gibbs relation, we show that the difference in the dynamics of these two systems at low temperatures can be explained from thermodynamics. At higher densities both the thermodynamical and dynamical difference between these model systems decrease, which is quantitatively demonstrated in this paper by calculating different parameters. The study also reveals the origin of the difference in pair entropy despite the similarity in the structure. Although the maximum difference in structure is obtained in the partial radial distribution function of the B type of particles, the rdf of AA pairs and AB pairs gives rise to the differences in the entropy and dynamics. This work supports the observation made in an earlier study [A. Banerjee et al., Phys. Rev. Lett. 113, 225701 (2014)] and shows that they are generic in nature, independent of density.

  20. QSPR study of supercooled liquid vapour pressures of PBDEs by using molecular distance-edge vector index

    Directory of Open Access Journals (Sweden)

    Jiao Long

    2015-01-01

    Full Text Available The quantitative structure property relationship (QSPR for supercooled liquid vapour pressures (PL of PBDEs was investigated. Molecular distance-edge vector (MDEV index was used as the structural descriptor. The quantitative relationship between the MDEV index and lgPL was modeled by using multivariate linear regression (MLR and artificial neural network (ANN respectively. Leave-one-out cross validation and k-fold cross validation were carried out to assess the prediction ability of the developed models. For the MLR method, the prediction root mean square relative error (RMSRE of leave-one-out cross validation and k-fold cross validation is 9.95 and 9.05 respectively. For the ANN method, the prediction RMSRE of leave-one-out cross validation and k-fold cross validation is 8.75 and 8.31 respectively. It is demonstrated the established models are practicable for predicting the lgPL of PBDEs. The MDEV index is quantitatively related to the lgPL of PBDEs. MLR and L-ANN are practicable for modeling this relationship. Compared with MLR, ANN shows slightly higher prediction accuracy. Subsequently, an MLR model, which regression equation is lgPL = 0.2868 M11 - 0.8449 M12 - 0.0605, and an ANN model, which is a two inputs linear network, were developed. The two models can be used to predict the lgPL of each PBDE.

  1. An apparatus with a horizontal capillary tube intended for measurement of the surface tension of supercooled liquids

    Directory of Open Access Journals (Sweden)

    Vinš Václav

    2015-01-01

    Full Text Available New experimental apparatus for measurement of the surface tension of liquids under the metastable supercooled state has been designed and assembled in the study. The measuring technique is similar to the method employed by P.T. Hacker [NACA TN 2510] in 1951. A short liquid thread of the liquid sample was sucked inside a horizontal capillary tube partly placed in a temperature-controlled glass chamber. One end of the capillary tube was connected to a setup with inert gas which allowed for precise tuning of the gas overpressure in order of hundreds of Pa. The open end of the capillary tube was precisely grinded and polished before the measurement in order to assure planarity and perpendicularity of the outer surface. The liquid meniscus at the open end was illuminated by a laser beam and observed by a digital camera. Application of an increasing overpressure of the inert gas at the inner meniscus of the liquid thread caused variation of the outer meniscus such that it gradually changed from concave to flat and subsequently convex shape. The surface tension at the temperature of the inner meniscus could be evaluated from the overpressure corresponding to exactly planar outer meniscus. Detailed description of the new setup together with results of the preliminary tests is provided in the study.

  2. Temperature dependence of density, thermal expansion coefficient and shear viscosity of supercooled glycerol as a reflection of its structure.

    Science.gov (United States)

    Blazhnov, Ivan V; Malomuzh, Nikolay P; Lishchuk, Sergey V

    2004-10-01

    The relationship of the microstructure of supercooled, highly viscous glycerol to the temperature dependence of its density, thermal expansion coefficient, and shear viscosity are discussed. The character of this temperature dependence at the transition from low viscosity state to the solid amorphous state (solidified state without nuclei) is described with help of function psi, which can be interpreted as the effective number of degrees of freedom responsible for the change of viscosity of glycerol over a broad range; these degrees of freedom are those related to the alpha-relaxation process. It is shown that the change in effective activation energy of the viscosity is completely determined by the parameter psi. The change in the shear viscosity of glycerol due to the influence of the solid-phase nuclei is considered. It is shown that the introduction of the parameter phi, equal to the specific volume occupied by the nuclei of the solid phase, together with psi provides a natural explanation of the temperature dependence of density and thermal expansion coefficients of glycerol in its liquid, solid amorphous, glassy, and crystal states. The peculiarities of the temperature dependence of phi(T) and psi(T) for glycerol and o-terphenyl are compared.

  3. A theoretical model investigation of peptide bond formation involving two water molecules in ribosome supports the two-step and eight membered ring mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qiang [School of Chemistry & Chemical Engineering, Shandong University, Jinan 250100 (China); Gao, Jun, E-mail: gaojun@sdu.edu.cn [Agricultural Bioinformatics Key Laboratory of Hubei Province, College of Informatics, Huazhong Agricultural University, Wuhan 430070 (China); School of Chemistry & Chemical Engineering, Shandong University, Jinan 250100 (China); Zhang, Dongju; Liu, Chengbu [School of Chemistry & Chemical Engineering, Shandong University, Jinan 250100 (China)

    2015-04-01

    Highlights: • We theoretical studied peptide bond formation reaction mechanism with two water molecules. • The first water molecule can decrease the reaction barriers by forming hydrogen bonds. • The water molecule mediated three-proton transfer mechanism is the favorable mechanism. • Our calculation supports the two-step and eight membered ring mechanism. - Abstract: The ribosome is the macromolecular machine that catalyzes protein synthesis. The kinetic isotope effect analysis reported by Strobel group supports the two-step mechanism. However, the destination of the proton originating from the nucleophilic amine is uncertain. A computational simulation of different mechanisms including water molecules is carried out using the same reaction model and theoretical level. Formation the tetrahedral intermediate with proton transfer from nucleophilic nitrogen, is the rate-limiting step when two water molecules participate in peptide bond formation. The first water molecule forming hydrogen bonds with O9′ and H15′ in the A site can decrease the reaction barriers. Combined with results of the solvent isotope effects analysis, we conclude that the three-proton transfer mechanism in which water molecule mediate the proton shuttle between amino and carbon oxygen in rate-limiting step is the favorable mechanism. Our results will shield light on a better understand the reaction mechanism of ribosome.

  4. Communication, perception and behaviour during a natural disaster involving a 'Do Not Drink' and a subsequent 'Boil Water' notice: a postal questionnaire study.

    Science.gov (United States)

    Rundblad, Gabriella; Knapton, Olivia; Hunter, Paul R

    2010-10-25

    During times of public health emergencies, effective communication between the emergency response agencies and the affected public is important to ensure that people protect themselves from injury or disease. In order to investigate compliance with public health advice during natural disasters, we examined consumer behaviour during two water notices that were issued as a result of serious flooding. During the summer of 2007, 140,000 homes in Gloucestershire, United Kingdom, that are supplied water from Mythe treatment works, lost their drinking water for up to 17 days. Consumers were issued a 'Do Not Drink' notice when the water was restored, which was subsequently replaced with a 'Boil Water' notice. The rare occurrence of two water notices provided a unique opportunity to compare compliance with public health advice. Information source use and other factors that may affect consumer perception and behaviour were also explored. A postal questionnaire was sent to 1,000 randomly selected households. Chi-square, ANOVA, MANOVA and generalised estimating equation (with and without prior factor analysis) were used for quantitative analysis. In terms of information sources, we found high use of and clear preference for the local radio throughout the incident, but family/friends/neighbours also proved crucial at the onset. Local newspapers and the water company were associated with clarity of advice and feeling informed, respectively. Older consumers and those in paid employment were particularly unlikely to read the official information leaflets. We also found a high degree of confusion regarding which notice was in place at which time, with correct recall varying between 23.2%-26.7%, and a great number of consumers believed two notices were in place simultaneously. In terms of behaviour, overall non-compliance levels were significantly higher for the 'Do Not Drink' notice (62.9%) compared to the 'Boil Water' notice (48.3%); consumers in paid employment were not likely to

  5. Communication, perception and behaviour during a natural disaster involving a 'Do Not Drink' and a subsequent 'Boil Water' notice: a postal questionnaire study

    Directory of Open Access Journals (Sweden)

    Knapton Olivia

    2010-10-01

    Full Text Available Abstract Background During times of public health emergencies, effective communication between the emergency response agencies and the affected public is important to ensure that people protect themselves from injury or disease. In order to investigate compliance with public health advice during natural disasters, we examined consumer behaviour during two water notices that were issued as a result of serious flooding. During the summer of 2007, 140,000 homes in Gloucestershire, United Kingdom, that are supplied water from Mythe treatment works, lost their drinking water for up to 17 days. Consumers were issued a 'Do Not Drink' notice when the water was restored, which was subsequently replaced with a 'Boil Water' notice. The rare occurrence of two water notices provided a unique opportunity to compare compliance with public health advice. Information source use and other factors that may affect consumer perception and behaviour were also explored. Method A postal questionnaire was sent to 1,000 randomly selected households. Chi-square, ANOVA, MANOVA and generalised estimating equation (with and without prior factor analysis were used for quantitative analysis. Results In terms of information sources, we found high use of and clear preference for the local radio throughout the incident, but family/friends/neighbours also proved crucial at the onset. Local newspapers and the water company were associated with clarity of advice and feeling informed, respectively. Older consumers and those in paid employment were particularly unlikely to read the official information leaflets. We also found a high degree of confusion regarding which notice was in place at which time, with correct recall varying between 23.2%-26.7%, and a great number of consumers believed two notices were in place simultaneously. In terms of behaviour, overall non-compliance levels were significantly higher for the 'Do Not Drink' notice (62.9% compared to the 'Boil Water' notice (48

  6. Local order parameters for use in driving homogeneous ice nucleation with all-atom models of water.

    Science.gov (United States)

    Reinhardt, Aleks; Doye, Jonathan P K; Noya, Eva G; Vega, Carlos

    2012-11-21

    We present a local order parameter based on the standard Steinhardt-Ten Wolde approach that is capable both of tracking and of driving homogeneous ice nucleation in simulations of all-atom models of water. We demonstrate that it is capable of forcing the growth of ice nuclei in supercooled liquid water simulated using the TIP4P/2005 model using over-biassed umbrella sampling Monte Carlo simulations. However, even with such an order parameter, the dynamics of ice growth in deeply supercooled liquid water in all-atom models of water are shown to be very slow, and so the computation of free energy landscapes and nucleation rates remains extremely challenging.

  7. Critical Processes Involved in Formulation of Water-in-Oil Fuel Emulsions, Combustion Efficiency of the Emulsified Fuels and Their Possible Environmental Impacts

    Directory of Open Access Journals (Sweden)

    A.N. Dibofori-Orji

    2011-08-01

    Full Text Available The aim of this study is to highlight some problems encountered during the formulation of water-inoil (w/o emulsions of diesel fuel. The combustion efficiency of the resultant emulsions and some pollutant gas emissions were determined. The paper also discussed possible environmental impacts of these emissions. Internal Combustion Engines (ICE find application in many modes of transportation including marine, land and air transportation. Economic and environmental considerations have led to the quest for improved combustion efficiency of the various fossil fuels used for these modes of transportation. The possibility of combustion of emulsified fuels has been the centre of some research efforts in the search for improved combustion efficiency. Diesel is mixed with water to form fuel-oil emulsions for combustion in some internal combustion engines. Depending on certain factors, two possible types of fuel-oil emulsions can be obtained: Oil in water and water in oil emulsions. Combustibility of the resulting emulsions was investigated. In this study, neat diesel was emulsified using polyethylene glycol as the emulsifying agent to produce water in oil emulsions. The water in oil emulsion was found to be combustible within certain limits of percentage content of water and air/fuel ratios. Problems encountered in the attempts to burn the emulsions include the nature and type of emulsifying agent, the method and means of mixing, as well as stability of the emulsions. This study shows that the emulsion containing 5% water had the highest combustion efficiency. Combustion of fuels, whether neat or emulsified, has some environmental impacts. Different noxious substances as exhaust products of combustion when emitted into the atmosphere could be injurious to human health, plants and animals within or close to the operating environments. In this study, the exhaust gases were analysed and their possible environmental impacts were discussed. The emulsion

  8. Effect of short-term decrease in water temperature on body temperature and involvement of testosterone in steelhead and rainbow trout, Oncorhynchus mykiss.

    Science.gov (United States)

    Miura, Go; Munakata, Arimune; Yada, Takashi; Schreck, Carl B; Noakes, David L G; Matsuda, Hiroyuki

    2013-09-01

    The Pacific salmonid species Oncorhynchus mykiss is separated into a migratory form (steelhead trout) and a non-migratory form (rainbow trout). A decrease in water temperature is likely a cue triggering downstream behavior in the migratory form, and testosterone inhibits onset of this behavior. To elucidate differences in sensitivity to water temperature decreases between the migratory and non-migratory forms and effect of testosterone on the sensitivity, we examined two experiments. In experiment 1, we compared changes in body temperature during a short-term decrease in water temperature between both live and dead steelhead and rainbow trout. In experiment 2, we investigated effects of testosterone on body temperature decrease in steelhead trout. Water temperature was decreased by 3°C in 30min. The body temperature of the steelhead decreased faster than that of the rainbow trout. In contrast, there was no significant difference in the decrease in body temperature between dead steelhead and rainbow trout specimens. The body temperature of the testosterone-treated steelhead trout decreased more slowly than that of control fish. Our results suggest that the migratory form is more sensitive to decreases in water temperature than the non-migratory form. Moreover, testosterone might play an inhibitory role in sensitivity to such decreases. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Exogenous spermidine improves seed germination of white clover under water stress via involvement in starch metabolism, antioxidant defenses and relevant gene expression.

    Science.gov (United States)

    Li, Zhou; Peng, Yan; Zhang, Xin-Quan; Ma, Xiao; Huang, Lin-Kai; Yan, Yan-Hong

    2014-11-05

    This study was designed to determine the effect of exogenous spermidine (Spd) (30 μM) on white clover seed germination under water stress induced by polyethylene glycol 6000. Use of seed priming with Spd improved seed germination percentage, germination vigor, germination index, root viability and length, and shortened mean germination time under different water stress conditions. Seedling fresh weight and dry weight also increased significantly in Spd-treated seeds compared with control (seeds primed with distilled water). Improved starch metabolism was considered a possible reason for this seed invigoration, since seeds primed with Spd had significantly increased α-amylase/β-amylase activities, reducing sugar, fructose and glucose content and transcript level of β-amylase gene but not transcript level of α-amylase gene. In addition, the physiological effects of exogenous Spd on improving seeds' tolerance to water deficit during germination were reflected by lower lipid peroxidation levels, better cell membrane stability and significant higher seed vigour index in seedlings. Enhanced antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase and ascorbate peroxidase), ascorbate-glutathione cycle (ASC-GSH cycle) and transcript level of genes encoding antioxidant enzymes induced by exogenous Spd may be one of the critical reasons behind acquired drought tolerance through scavenging of reactive oxygen species (ROS) in water-stressed white clover seeds. The results indicate that Spd plays an important function as a stress-protective compound or physiological activator.

  10. Exogenous Spermidine Improves Seed Germination of White Clover under Water Stress via Involvement in Starch Metabolism, Antioxidant Defenses and Relevant Gene Expression

    Directory of Open Access Journals (Sweden)

    Zhou Li

    2014-11-01

    Full Text Available This study was designed to determine the effect of exogenous spermidine (Spd (30 μM on white clover seed germination under water stress induced by polyethylene glycol 6000. Use of seed priming with Spd improved seed germination percentage, germination vigor, germination index, root viability and length, and shortened mean germination time under different water stress conditions. Seedling fresh weight and dry weight also increased significantly in Spd-treated seeds compared with control (seeds primed with distilled water. Improved starch metabolism was considered a possible reason for this seed invigoration, since seeds primed with Spd had significantly increased α-amylase/β-amylase activities, reducing sugar, fructose and glucose content and transcript level of β-amylase gene but not transcript level of α-amylase gene. In addition, the physiological effects of exogenous Spd on improving seeds’ tolerance to water deficit during germination were reflected by lower lipid peroxidation levels, better cell membrane stability and significant higher seed vigour index in seedlings. Enhanced antioxidant enzyme activities (superoxide dismutase, peroxidase, catalase and ascorbate peroxidase, ascorbate-glutathione cycle (ASC-GSH cycle and transcript level of genes encoding antioxidant enzymes induced by exogenous Spd may be one of the critical reasons behind acquired drought tolerance through scavenging of reactive oxygen species (ROS in water-stressed white clover seeds. The results indicate that Spd plays an important function as a stress-protective compound or physiological activator.

  11. Raman Spectra and Nucleation Rates of Sulfuric Acid and Ammonium Sulfate Aerosols Supercooled with Respect to Ice

    Science.gov (United States)

    Knopf, D. A.; Koop, T.; Weers, U. G.; Krieger, U. K.; Peter, T.

    2001-12-01

    Sulfuric acid and ammonium sulfate aerosol particles can serve as ice condensation nuclei for the formation of upper tropospheric cirrus clouds. These clouds influence the global radiation budget by scattering of short wavelength (solar) radiation as well as by absorbing long wavelength (terrestrial) radiation. Knowledge of the thermodynamics and the nucleation rates of aerosols is fundamental for the understanding of formation processes of cirrus clouds. Here, we present a new investigation tool to observe phase transitions of aerosols supercooled with respect to ice. Confocal Raman microscopy is used to determine the phase changes and the morphology of the particles. Raman spectroscopy is employed to distinguish and to characterize the different phases inside the frozen particles. Single droplets with a diameter of typically 20-120 μ m are deposited on a hydrophobically coated Herasil-plate that is covered by a spacer and another plate. Since the gas phase volume of the cell is small compared to the liquid droplet volume the composition of the droplets remains fixed during temperature changes. The temperature of the droplets can be varied between 150-350~K. We present the first Raman spectra of aqueous H2SO4/H2O and (NH4)2SO4/H2O droplets for several concentrations and temperatures to the homogeneous ice nucleation limits. The analysis of the speciation of the components inside the droplets (e.g. sulfate vs. bisulfate ions) is compared to results from thermodynamic models. Evaluation of the freezing data gives upper limits for ice nucleation rates of droplets as a function of sulfuric acid or ammonium sulfate concentration.

  12. Molecular dynamics investigation of dynamical heterogeneity and local structure in the supercooled liquid and glass states of Al

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Wang, C. Z.; Mandelev, M.; Ho, K. M.

    2008-05-13

    Molecular dynamics simulations are performed to study the structure and dynamical heterogeneity in the liquid and glass states of Al using a frequently employed embedded atom potential. While the pair correlation function of the glass and liquid states displays only minor differences, the icosahedral short-range order (ISRO) and the dynamics of the two states are very different. The ISRO is much stronger in the glass than in the liquid. It is also found that both the most mobile and the most immobile atoms in the glass state tend to form clusters, and the clusters formed by the immobile atoms are more compact. In order to investigate the local environment of each atom in the liquid and glass states, a local density is defined to characterize the local atomic packing. There is a strong correlation between the local packing density and the mobility of the atoms. These results indicate that dynamical heterogeneity in glasses is directly correlated to the local structure. We also analyze the diffusion mechanisms of atoms in the liquid and glass states. It is found that for the mobile atoms in the glass state, initially they are confined in the cages formed by their nearest neighbors and vibrating. On the time scale of {beta} relaxation, the mobile atoms try to break up the cage confinement and hop into new cages. In the supercooled liquid states, however, atoms continuously diffuse. Furthermore, it is found that on the time scale of {beta} relaxation, some of the mobile atoms in the glass state cooperatively hop, which is facilitated by the stringlike cluster structures. On the longer time scale, it is found that a certain fraction of atoms can simultaneously hop, although they are not nearest neighbors. Further analysis shows that these hopping atoms form big and more compact clusters than the characterized most mobile atoms. The cooperative rearrangement of these big compact clusters might facilitate the simultaneous hopping of atoms in the glass states on the long

  13. Removal of sulfamethoxazole sulfonamide antibiotic from water by high silica zeolites: a study of the involved host-guest interactions by a combined structural, spectroscopic, and computational approach.

    Science.gov (United States)

    Blasioli, Sonia; Martucci, Annalisa; Paul, Geo; Gigli, Lara; Cossi, Maurizio; Johnston, Cliff T; Marchese, Leonardo; Braschi, Ilaria

    2014-04-01

    Sulfonamide antibiotics are persistent pollutants present in surface and subsurface waters in both agricultural and urban environments. Sulfonamides are of particular concern in the environment because they are known to induce high levels of bacterial resistance. Adsorption of sulfamethoxazole sulfonamide antibiotic into three high silica zeolites (Y, mordenite, and ZSM-5) with pore opening sizes comparable to sulfamethoxazole dimensions is reported. Sulfamethoxazole was almost completely removed from water by zeolite Y and MOR in a few minutes. Adsorption onto ZSM-5 showed an increased kinetics with increasing temperature. Antibiotic sorption was largely irreversible with little antibiotic desorbed. Sulfamethoxazole incorporation and localization into the pore of each zeolite system was defined along with medium-weak and cooperative host-guest interactions in which water molecules play a certain role only in zeolite Y and mordenite.

  14. Heat transfer characteristics of boiling R134a in forced supercooled flows; Waermeuebergang beim Sieden von R134a in erzwungener unterkuehlter Stroemung

    Energy Technology Data Exchange (ETDEWEB)

    Spindler, K.; Hahne, E. [Stuttgart Univ. (Germany). Inst. fuer Thermodynamik und Waermetechnik

    2000-07-01

    Supercooled boiling is characterized by evaporation at the heating surface although the average temperature of the fluid is still below saturation temperature. There is a superheated metastable boundary layer at the wall in which steam bubbles nucleate and grow. They recondense when they enter the turbulent supercooled flow because of volume increase or detachment from the wall. This phenomenon results in a significant improvement of heat transfer as compared with single-phase forced convection. The contribution presents experimental findings on the heat transfer characteristics of R134a in forced supercooled flow. [German] Das unterkuehlte Sieden ist dadurch gekennzeichnet, dass an der Heizflaeche Verdampfung auftritt, obwohl die Fluessigkeit im Mittel noch nicht die zum Druck gehoerende Saettigungstemperatur erreicht hat. In unmittelbarer Wandnaehe ist eine ueberhitzte metastabile Grenzschicht vorhanden, in der die Dampfblasen an Blasenkeimstellen entstehen und wachsen. Sobald sie wegen ihrer Volumenzunahme oder Abloesung aus der ueberhitzten Grenzschicht in die turbulente, unterkuehlte Kernstroemung gelangen, kondensieren sie wieder. Dieser Vorgang fuehrt zu einer deutlichen Verbesserung des Waermeuebergangs gegenueber der einphasigen erzwungenen Konvektion. Es werden experimentelle Ergebnisse zum Waermeuebergang beim Sieden von R134a in erzwungener unterkuehlter Stroemung vorgestellt. Die Messstrecke ist ein senkrecht angeordnetes, gezogenes Kupferrohr mit einer Laenge von 550 mm und einem Innendurchmesser von 20 mm. Die Messstrecke wird mit Miniatur-Mantelheizleitern beheizt, die in spiralfoermig aussen umlaufende Nuten eingestemmt und zusaetzlich mit Waermeleitzement fixiert sind. Die Versuchsparameter wurden in folgenden Bereichen variiert: Massenstromdichte von 1000 bis 2000 kg/(m{sup 2}s), Waermestromdichte bis 100000 W/m{sup 2}, Unterkuehlung von 2 bis 11 K, Druck zwischen 8 und 10 bar. Die Waermeuebergangskoeffizienten werden mit Nusseltkorrelationen der

  15. Thermodynamic properties of bulk and confined water

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienza della Terra Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienza della Terra Università di Messina and CNISM, I-98168 Messina (Italy); Mallamace, Domenico [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano; Vasi, Cirino [IPCF-CNR, I-98166 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States)

    2014-11-14

    The thermodynamic response functions of water display anomalous behaviors. We study these anomalous behaviors in bulk and confined water. We use nuclear magnetic resonance (NMR) to examine the configurational specific heat and the transport parameters in both the thermal stable and the metastable supercooled phases. The data we obtain suggest that there is a behavior common to both phases: that the dynamics of water exhibit two singular temperatures belonging to the supercooled and the stable phase, respectively. One is the dynamic fragile-to-strong crossover temperature (T{sub L} ≃ 225 K). The second, T{sup *} ∼ 315 ± 5 K, is a special locus of the isothermal compressibility K{sub T}(T, P) and the thermal expansion coefficient α{sub P}(T, P) in the P–T plane. In the case of water confined inside a protein, we observe that these two temperatures mark, respectively, the onset of protein flexibility from its low temperature glass state (T{sub L}) and the onset of the unfolding process (T{sup *})

  16. Facilitating Conceptual Understanding of Gas-Liquid Mass Transfer Coefficient through a Simple Experiment Involving Dissolution of Carbon Dioxide in Water in a Surface Aeration Reactor

    Science.gov (United States)

    Utgikar, Vivek P.; MacPherson, David

    2016-01-01

    Students in the undergraduate "transport phenomena" courses typically have a greater difficulty in understanding the theoretical concepts underlying the mass transport phenomena as compared to the concepts of momentum and energy transport. An experiment based on dissolution of carbon dioxide in water was added to the course syllabus to…

  17. Facilitating Conceptual Understanding of Gas-Liquid Mass Transfer Coefficient through a Simple Experiment Involving Dissolution of Carbon Dioxide in Water in a Surface Aeration Reactor

    Science.gov (United States)

    Utgikar, Vivek P.; MacPherson, David

    2016-01-01

    Students in the undergraduate "transport phenomena" courses typically have a greater difficulty in understanding the theoretical concepts underlying the mass transport phenomena as compared to the concepts of momentum and energy transport. An experiment based on dissolution of carbon dioxide in water was added to the course syllabus to…

  18. The anomalous behavior of the density of water in the range 30 K < T < 373 K

    OpenAIRE

    Mallamace, Francesco; Branca, Caterina; Broccio, Matteo; Corsaro, Carmelo; Mou, Chung-Yuan; Chen, Sow-Hsin

    2007-01-01

    The temperature dependence of the density of water, ρ(T), is obtained by means of optical scattering data, Raman and Fourier transform infrared, in a very wide temperature range, 30 < T < 373 K. This interval covers three regions: the thermodynamically stable liquid phase, the metastable supercooled phase, and the low-density amorphous solid phase, at very low T. From analyses of the profile of the OH stretching spectra, we determine the fractional weight of the two main spectral components c...

  19. Spectroscopic, Electrochemical and Computational Characterisation of Ru Species Involved in Catalytic Water Oxidation: Evidence for a [RuV(O)(Py2Metacn)] Intermediate

    OpenAIRE

    Casadevall, Carla; Codolà Duch, Zoel; Costas Salgueiro, Miquel; Lloret Fillol, Julio

    2016-01-01

    A new family of ruthenium complexes based on the N-pentadentate ligand Py2Metacn (N-methyl-N′,N′′-bis(2-picolyl)-1,4,7-triazacyclononane) has been synthesised and its catalytic activity has been studied in the water-oxidation (WO) reaction. We have used chemical oxidants (ceric ammonium nitrate and NaIO4) to generate the WO intermediates [RuII(OH2)(Py2Metacn)]2+, [RuIII(OH2)(Py2Metacn)]3+, [RuIII(OH)(Py2Metacn)]2+ and [RuIV(O)(Py2Metacn)]2+, which have been characterised spectroscopically. Th...

  20. A highly modular beamline electrostatic levitation facility, optimized for in situ high-energy x-ray scattering studies of equilibrium and supercooled liquids.

    Science.gov (United States)

    Mauro, N A; Kelton, K F

    2011-03-01

    High-energy x-ray diffraction studies of metallic liquids provide valuable information about structural evolution on the atomic length scale, leading to insights into the origin of the nucleation barrier and the processes of supercooling and glass formation. The containerless processing of the beamline electrostatic levitation (BESL) facility allows coordinated thermophysical and structural studies of equilibrium and supercooled liquids to be made in a contamination-free, high-vacuum (∼10(-8) Torr) environment. To date, the incorporation of electrostatic levitation facilities into synchrotron beamlines has been difficult due to the large footprint of the apparatus and the difficulties associated with its transportation and implementation. Here, we describe a modular levitation facility that is optimized for diffraction studies of high-temperature liquids at high-energy synchrotron beamlines. The modular approach used in the apparatus design allows it to be easily transported and quickly setup. Unlike most previous electrostatic levitation facilities, BESL can be operated by a single user instead of a user team.

  1. Theoretical analysis of supercooling phenomenon by phase equilibrium condition%用相平衡条件对过冷却现象的理论分析

    Institute of Scientific and Technical Information of China (English)

    郑歆

    2001-01-01

    The supercooling phenomenon in living beings is analyzed by phase equilibrium conditions. The ice point depression of aqueous solution in living being cell is estimated. The result shows that the pressure has little effect on ice point of aqueous solution in living being, while concentration has great effect on ice point. The significance of supercooling phenomenon for cold resistance of living being is explained briefly.%利用相平衡条件简要分析了生物体内的过冷却现象;对生物体细胞内水溶液冰点的降低作了估算,得出压强对细胞内水溶液冰点的影响不大,而浓度对细胞内水溶液冰点则有较大的影响的结论.简要地说明了过冷却现象对于生物的耐寒性的意义.

  2. O contexto global e nacional frente aos desafios do acesso adequado à água para consumo humano The global and national context regarding the challenges involved in ensuring adequate access to water for human consumption

    Directory of Open Access Journals (Sweden)

    Lia Giraldo da Silva Augusto

    2012-06-01

    Full Text Available Este artigo tem como objetivo analisar os desafios do acesso à água para consumo humano, considerando-se o contexto internacional e nacional. A partir da deliberação da ONU de que o acesso à água limpa e segura é um direito fundamental de todo ser humano são identificadas vulnerabilidades que podem se constituir em restrições ao acesso. A distribuição da água e das populações no planeta, a poluição, as políticas e gestões inadequadas produzem injustiça ambiental. A iniquidade de acesso a água constitui-se na crise contemporânea da água. A partir da década de 1980, emerge o mercado transnacional de água pelo controle privado que ocorre em três níveis principais: de mananciais superficiais e subterrâneos; de água engarrafada; e dos serviços públicos de abastecimento. Os conflitos dos usos múltiplos dos recursos hídricos, do mercado e dos problemas ambientais têm contribuído para a vulnerabilização da saúde das populações e dos ecossistemas. São necessárias políticas públicas adequadas ao exercício do direito humano fundamental de acesso a água com qualidade.The scope of this article is to analyze the challenges involved in ensuring access to water for human consumption taking the international and national context into consideration. Based on the UN declaration that access to safe and clean drinking water is a fundamental human right, vulnerabilities are identified that can consist in restrictions to access to adequate supplies. The distribution of water and the population across the planet, pollution, inadequate policies and management lead to environmental injustice. The iniquity of access to water constitutes the contemporary water crisis. From the 1980s onwards, the transnational water market emerged for private control that occurs at three main levels: surface and underground water sources; bottled water; and public water supply services. The conflicts of the multiple uses of water resources, the

  3. A new route for the prebiotic synthesis of nucleobases and hydantoins in water/ice solutions involving the photochemistry of acetylene.

    Science.gov (United States)

    Menor-Salván, César; Marín-Yaseli, Margarita R

    2013-05-10

    The origin of nucleobases and other heterocycles is a classic question in the chemistry of the origins of life. The construction of laboratory models for the abiotic synthesis of nitrogen heterocycles in plausible natural conditions also aids the understanding and prediction of chemical species in the Solar System. Here, we report a new explanation for the origin of hydantoins, purines, and pyrimidines in eutectic water/ice/urea solutions driven by ultraviolet irradiation (in the 185-254 nm range, UVC) of acetylene under anoxic conditions. An analysis of the products indicates the synthesis of hydantoin and 5-hydroxyhydantoin, the purines uric acid, xanthine, and guanine, and the pyrimidines uracil and cytosine. The synthesis occurred together with the photo-oxidation of bases in a complex process for which possible pathways are proposed. In conclusion, an acetylene-containing atmosphere could contribute to the origin of nucleobases in the presence of a urea/water system by an HCN-independent mechanism. The presence of ice has a dual role as a favorable medium for the synthesis of nucleobases and protection against degradation and as a source of free radicals for the synthesis of highly oxidized heterocycles. A mechanism for the origin of hydantoins and uracil from urea in plausible conditions for prebiotic chemistry is also proposed.

  4. Analysis for the presence of determinants involved in the transport of mercury across bacterial membrane from polluted water bodies of India

    Directory of Open Access Journals (Sweden)

    Arif Tasleem Jan

    2016-03-01

    Full Text Available Abstract Mercury, which is ubiquitous and recalcitrant to biodegradation processes, threatens human health by escaping to the environment via various natural and anthropogenic activities. Non-biodegradability of mercury pollutants has necessitated the development and implementation of economic alternatives with promising potential to remove metals from the environment. Enhancement of microbial based remediation strategies through genetic engineering approaches provides one such alternative with a promising future. In this study, bacterial isolates inhabiting polluted sites were screened for tolerance to varying concentrations of mercuric chloride. Following identification, several Pseudomonas and Klebsiella species were found to exhibit the highest tolerance to both organic and inorganic mercury. Screened bacterial isolates were examined for their genetic make-up in terms of the presence of genes (merP and merT involved in the transport of mercury across the membrane either alone or in combination to deal with the toxic mercury. Gene sequence analysis revealed that the merP gene showed 86–99% homology, while the merT gene showed >98% homology with previously reported sequences. By exploring the genes involved in imparting metal resistance to bacteria, this study will serve to highlight the credentials that are particularly advantageous for their practical application to remediation of mercury from the environment.

  5. Determination of octanol-air partition coefficients and supercooled liquid vapor pressures of PAHs as a function of temperature: Application to gas-particle partitioning in an urban atmosphere

    Science.gov (United States)

    Odabasi, Mustafa; Cetin, Eylem; Sofuoglu, Aysun

    Octanol-air partition coefficients ( KOA) for 14 polycyclic aromatic hydrocarbons (PAHs) were determined as a function of temperature using the gas chromatographic retention time method. log KOA values at 25° ranged over six orders of magnitude, between 6.34 (acenaphthylene) and 12.59 (dibenz[ a,h]anthracene). The determined KOA values were within factor of 0.7 (dibenz[ a,h]anthracene) to 15.1 (benz[ a]anthracene) of values calculated as the ratio of octanol-water partition coefficient to dimensionless Henry's law constant. Supercooled liquid vapor pressures ( PL) of 13 PAHs were also determined using the gas chromatographic retention time technique. Activity coefficients in octanol calculated using KOA and PL ranged between 3.2 and 6.2 indicating near-ideal solution behavior. Atmospheric concentrations measured in this study in Izmir, Turkey were used to investigate the partitioning of PAHs between particle and gas-phases. Experimental gas-particle partition coefficients ( Kp) were compared to the predictions of KOA absorption and KSA (soot-air partition coefficient) models. Octanol-based absorptive partitioning model predicted lower partition coefficients especially for relatively volatile PAHs. Ratios of measured/modeled partition coefficients ranged between 1.1 and 15.5 (4.5±6.0, average±SD) for KOA model. KSA model predictions were relatively better and measured to modeled ratios ranged between 0.6 and 5.6 (2.3±2.7, average±SD).

  6. Comparing differences in teacher learning and involvement in water quality activities with the use of a Web tutorial and with face-to-face instruction

    Science.gov (United States)

    Cleveland, April Jones

    The integration of technology into the K--12 classroom has become a key focus in the last several years. However, teachers are often left out of this integration process, and subsequently training in the use of the technologies in a classroom setting is often minimal in nature. Teachers are left on their own as they struggle to integrate technology into their curriculum. Web-based professional development has the potential to alleviate both time and place constraints teachers often confront when trying to attend traditional professional programs to upgrade their technology skills. This study focuses on 70 upper elementary, middle, and high school teachers who volunteered to take part in this study in which a web-based tutorial was used as a tool for professional development and data collection. A comparison of settings allowed these teachers to participate in one of three ways: (1) in a workshop-type setting with an instructional leader; (2) in a workshop-type setting with a facilitator; and (3) on the web without an instructional leader or informal peer interaction. All the groups used the same web-based tutorial on water quality monitoring for instructional purposes. Research data included pretest and post-test measurement from all three groups as well as their analysis of a known water sample. The Microcomputer Utilization in Teaching Efficacy Beliefs Instrument (MUTEBI) was administered to all the participants as a measurement of self-efficacy beliefs as they relate to the use of computers in science teaching. In addition to the quantitative data collected, qualitative data was also compiled. The results of the study indicate that all the participants were equal in terms of knowledge acquisition, but may have derived "unanticipated benefits" from interaction with their peers in the workshop-type settings. The results also indicate that as teachers' self-rating of computer expertise increased, their scores on the Microcomputer Utilization in Teaching Efficacy

  7. Starch-related alpha-glucan/water dikinase is involved in the cold-induced development of freezing tolerance in Arabidopsis.

    Science.gov (United States)

    Yano, Ryoichi; Nakamura, Masanobu; Yoneyama, Tadakatsu; Nishida, Ikuo

    2005-06-01

    Cold-induced soluble sugar accumulation enhances the degree of freezing tolerance in various cold-hardy plants including Arabidopsis (Arabidopsis thaliana), where soluble sugars accumulate in only a few hours at 2 degrees C. Hence, along with photosynthesis, starch degradation might play a significant role in cold-induced sugar accumulation and enhanced freezing tolerance. Starch-related alpha-glucan/water dikinase (EC 2.7.9.4), encoded by Arabidopsis STARCH EXCESS 1 (SEX1), is hypothesized to regulate starch degradation in plastids by phosphorylating starch, thereby ensuring better accessibility by starch-degrading enzymes. Here, we show that Arabidopsis sex1 mutants, when incubated at 2 degrees C for 1 d, were unable to accumulate maltooligosaccharides or normal glucose and fructose levels. In addition, they displayed impaired freezing tolerance. After 7 d at 2 degrees C, sex1 mutants did not show any of the above abnormal phenotypes but displayed slightly higher leaf starch contents. The impaired freezing tolerance of sex1 mutants was restored by overexpression of wild-type SEX1 cDNA using the cauliflower mosaic virus 35S promoter. The results demonstrate a genetic link between the SEX1 locus and plant freezing tolerance, and show that starch degradation is important for enhanced freezing tolerance during an early phase of cold acclimation. However, induction of starch degradation was not accompanied by significant changes in alpha-glucan/water dikinase activity in leaf extracts and preceded cold-induced augmentation of SEX1 transcripts. Therefore, we conclude that augmentation of SEX1 transcripts might be a homeostatic response to low temperature, and that starch degradation during an early phase of cold acclimation could be regulated by a component(s) of a starch degradation pathway(s) downstream of SEX1.

  8. Protein kinase C is involved with upstream signaling of methyl farnesoate for photoperiod-dependent sex determination in the water flea Daphnia pulex

    Directory of Open Access Journals (Sweden)

    Kenji Toyota

    2017-02-01

    Full Text Available Sex determination of Daphnia pulex is decided by environmental conditions. We established a suitable experimental system for this study using D. pulex WTN6 strain, in which the sex of the offspring can be controlled by photoperiod. Long-day conditions induced females and short-day conditions induced males. Using this system, we previously found that methy farnesoate (MF, which is a putative innate juvenile hormone molecule in daphnids, is necessary for male sex determination and that protein kinase C (PKC is a candidate factor of male sex determiner. In this study, we demonstrated that a PKC inhibitor [bisindolylmaleimide IV (BIM] application strongly suppressed male offspring induction in the short-day condition. Moreover, co-treatment of BIM with MF revealed that PKC signaling acts upstream of MF signaling for male sex determination. This is the first experimental evidence that PKC is involved in the male sex determination process associated with methyl farnesoate signaling in daphnid species.

  9. Photochemical processes involving the UV absorber benzophenone-4 (2-hydroxy-4-methoxybenzophenone-5-sulphonic acid) in aqueous solution: reaction pathways and implications for surface waters.

    Science.gov (United States)

    De Laurentiis, Elisa; Minella, Marco; Sarakha, Mohamed; Marrese, Alessandro; Minero, Claudio; Mailhot, Gilles; Brigante, Marcello; Vione, Davide

    2013-10-01

    The sunlight filter benzophenone-4 (BP-4) is present in surface waters as two prevailing forms, the singly deprotonated (HA-) and the doubly deprotonated one (A(2-)), with pKa2 = 7.30 ± 0.14 (μ ± σ, by dissociation of the phenolic group). In freshwater environments, BP-4 would mainly undergo degradation by reaction with ·OH and direct photolysis. The form HA(-) has a second-order reaction rate constant with ·OH (k(·OH)) of (1.87 ± 0.31)·10(10) M(-1) s(-1) and direct photolysis quantum yield Φ equal to (3.2 ± 0.6)·10(-5). The form A(2-) has (8.46 ± 0.24)·10(9) M(-1) s(-1) as the reaction rate constant with ·OH and (7.0 ± 1.3)·10(-5) as the photolysis quantum yield. The direct photolysis of HA(-) likely proceeds via homolytic breaking of the O-H bond of the phenolic group to give the corresponding phenoxy radical, as suggested by laser flash photolysis experiments. Photochemical modelling shows that because of more efficient direct photolysis (due to both higher sunlight absorption and higher photolysis quantum yield), the A(2-) form can be degraded up to 3 times faster than HA(-) in surface waters. An exception is represented by low-DOC (dissolved organic carbon) conditions, where the ·OH reaction dominates degradation and the transformation kinetics of HA(-) is faster compared to A(2-). The half-life time of BP-4 in mid-latitude summertime would be in the range of days to weeks, depending on the environmental conditions. BP-4 also reacts with Br2(·-), and a rate constant k(Br2(·-),BP-4) = (8.05 ± 1.33)·10(8) M(-1) s(-1) was measured at pH 7.5. Model results show that reaction with Br2(·-) could be a potentially important transformation pathway of BP-4 in bromide-rich (e.g. seawater) and DOM-rich environments.

  10. Starch-binding domains in the CBM45 family--low-affinity domains from glucan, water dikinase and α-amylase involved in plastidial starch metabolism.

    Science.gov (United States)

    Glaring, Mikkel A; Baumann, Martin J; Abou Hachem, Maher; Nakai, Hiroyuki; Nakai, Natsuko; Santelia, Diana; Sigurskjold, Bent W; Zeeman, Samuel C; Blennow, Andreas; Svensson, Birte

    2011-04-01

    Starch-binding domains are noncatalytic carbohydrate-binding modules that mediate binding to granular starch. The starch-binding domains from the carbohydrate-binding module family 45 (CBM45, http://www.cazy.org) are found as N-terminal tandem repeats in a small number of enzymes, primarily from photosynthesizing organisms. Isolated domains from representatives of each of the two classes of enzyme carrying CBM45-type domains, the Solanum tuberosumα-glucan, water dikinase and the Arabidopsis thaliana plastidial α-amylase 3, were expressed as recombinant proteins and characterized. Differential scanning calorimetry was used to verify the conformational integrity of an isolated CBM45 domain, revealing a surprisingly high thermal stability (T(m) of 84.8 °C). The functionality of CBM45 was demonstrated in planta by yellow/green fluorescent protein fusions and transient expression in tobacco leaves. Affinities for starch and soluble cyclodextrin starch mimics were measured by adsorption assays, surface plasmon resonance and isothermal titration calorimetry analyses. The data indicate that CBM45 binds with an affinity of about two orders of magnitude lower than the classical starch-binding domains from extracellular microbial amylolytic enzymes. This suggests that low-affinity starch-binding domains are a recurring feature in plastidial starch metabolism, and supports the hypothesis that reversible binding, effectuated through low-affinity interaction with starch granules, facilitates dynamic regulation of enzyme activities and, hence, of starch metabolism.

  11. Mercury bioaccumulation in the aquatic plant Elodea nuttallii in the field and in microcosm: accumulation in shoots from the water might involve copper transporters.

    Science.gov (United States)

    Regier, Nicole; Larras, Floriane; Bravo, Andrea Garcia; Ungureanu, Viorel-Gheorghe; Amouroux, David; Cosio, Claudia

    2013-01-01

    Previous studies suggest that macrophytes might participate in bioaccumulation and biomagnification of toxic mercury (Hg) in aquatic environment. Hg bioaccumulation and uptake mechanisms in macrophytes need therefore to be studied. Amongst several macrophytes collected in an Hg contaminated reservoir in Romania, Elodea nuttallii showed a high organic and inorganic Hg accumulation and was then further studied in the laboratory. Tolerance and accumulation of Hg of this plant was also high in the microcosm. Basipetal transport of inorganic Hg was predominant, whereas acropetal transport of methyl-Hg was observed with apparently negligible methylation or demethylation in planta. Hg concentrations were higher in roots>leaves>stems and in top>middle>bottom of shoots. In shoots, more than 60% Hg was found intracellularly where it is believed to be highly available to predators. Accumulation in shoots was highly reduced by cold, death and by competition with Cu(+). Hg in E. nuttallii shoots seems to mainly originate from the water column, but methyl-Hg could also be remobilized from the sediments and might drive in part its entry in the food web. At the cellular level, uptake of Hg into the cell sap of shoots seems linked to the metabolism and to copper transporters. The present work highlights an important breakthrough in our understanding of Hg accumulation and biomagnifications: the remobilization of methyl-Hg from sediments to aquatic plants and differences in uptake mechanisms of inorganic and methyl-Hg in a macrophyte.

  12. Protein kinase C is involved with upstream signaling of methyl farnesoate for photoperiod-dependent sex determination in the water flea Daphnia pulex.

    Science.gov (United States)

    Toyota, Kenji; Sato, Tomomi; Tatarazako, Norihisa; Iguchi, Taisen

    2017-02-15

    Sex determination of Daphnia pulex is decided by environmental conditions. We established a suitable experimental system for this study using D. pulex WTN6 strain, in which the sex of the offspring can be controlled by photoperiod. Long-day conditions induced females and short-day conditions induced males. Using this system, we previously found that methy farnesoate (MF), which is a putative innate juvenile hormone molecule in daphnids, is necessary for male sex determination and that protein kinase C (PKC) is a candidate factor of male sex determiner. In this study, we demonstrated that a PKC inhibitor [bisindolylmaleimide IV (BIM)] application strongly suppressed male offspring induction in the short-day condition. Moreover, co-treatment of BIM with MF revealed that PKC signaling acts upstream of MF signaling for male sex determination. This is the first experimental evidence that PKC is involved in the male sex determination process associated with methyl farnesoate signaling in daphnid species. © 2017. Published by The Company of Biologists Ltd.

  13. Determination of molecular groups involved in the interaction of annexin A5 with lipid membrane models at the air-water interface.

    Science.gov (United States)

    Fezoua-Boubegtiten, Zahia; Desbat, Bernard; Brisson, Alain; Lecomte, Sophie

    2010-06-01

    Annexin A5 (AnxA5) is a member of a family of homologous proteins sharing the ability to bind to negatively charged phospholipid membranes in a Ca(2+)-dependent manner. In this paper, we used polarization-modulated infrared reflection absorption spectroscopy (PMIRRAS), Brewster angle microscopy (BAM), and ellipsometry to investigate changes both in the structure of AnxA5 and phospholipid head groups associated with membrane binding. We found that the secondary structure of AnxA5 in the AnxA5/Ca(2+)/lipid ternary complex is conserved, mainly in alpha-helices and the average orientation of the alpha-helices of the protein is slightly tilted with respect to the normal to the phospholipid monolayer. Upon interaction between AnxA5 and phospholipids, a shift of the nu(as) PO(2)(-) band is observed by PMIRRAS. This reveals that the phosphate group is the main group involved in the binding of AnxA5 to phospholipids via Ca(2+) ions, even when some carboxylate groups are accessible (PS). PMIRRAS spectra also indicate a change of carboxylate orientation in the aspartate and glutamate residues implicated in the association of the AnxA5, which could be linked to the 2D crystallization of protein under the phospholipid monolayer. Finally, we demonstrated that the interaction of AnxA5 with pure carboxylate groups of an oleic acid monolayer is possible, but the orientation of the protein under the lipid is completely different.

  14. A physically constrained classical description of the homogeneous nucleation of ice in water

    Science.gov (United States)

    Koop, Thomas; Murray, Benjamin J.

    2016-12-01

    Liquid water can persist in a supercooled state to below 238 K in the Earth's atmosphere, a temperature range where homogeneous nucleation becomes increasingly probable. However, the rate of homogeneous ice nucleation in supercooled water is poorly constrained, in part, because supercooled water eludes experimental scrutiny in the region of the homogeneous nucleation regime where it can exist only fleetingly. Here we present a new parameterization of the rate of homogeneous ice nucleation based on classical nucleation theory. In our approach, we constrain the key terms in classical theory, i.e., the diffusion activation energy and the ice-liquid interfacial energy, with physically consistent parameterizations of the pertinent quantities. The diffusion activation energy is related to the translational self-diffusion coefficient of water for which we assess a range of descriptions and conclude that the most physically consistent fit is provided by a power law. The other key term is the interfacial energy between the ice embryo and supercooled water whose temperature dependence we constrain using the Turnbull correlation, which relates the interfacial energy to the difference in enthalpy between the solid and liquid phases. The only adjustable parameter in our model is the absolute value of the interfacial energy at one reference temperature. That value is determined by fitting this classical model to a selection of laboratory homogeneous ice nucleation data sets between 233.6 K and 238.5 K. On extrapolation to temperatures below 233 K, into a range not accessible to standard techniques, we predict that the homogeneous nucleation rate peaks between about 227 and 231 K at a maximum nucleation rate many orders of magnitude lower than previous parameterizations suggest. This extrapolation to temperatures below 233 K is consistent with the most recent measurement of the ice nucleation rate in micrometer-sized droplets at temperatures of 227-232 K on very short time scales

  15. Direct measurements of quantum kinetic energy tensor in stable and metastable water near the triple point: an experimental benchmark

    CERN Document Server

    Andreani, Carla; Senesi, Roberto

    2016-01-01

    This study presents the first direct and quantitative measurements of the nuclear momentum distribution anisotropy and the quantum kinetic energy tensor in stable and metastable (supercooled) water near its triple point using Deep Inelastic Neutron Scattering (DINS). From the experimental spectra accurate lineshapes of the hydrogen momentum distributions are derived using an anisotropic Gaussian and a model independent framework. The experimental results, benchmarked with those obtained for the solid phase, provide the state of the art directional values of the hydrogen mean kinetic energy in metastable water. The determinations of the direction kinetic energies in the supercooled phase, benchmarked with ice at the same temperature, provide accurate and quantitative measurements of these dynamical observables in metastable and stable phases, {i.e.} key insight in the physical mechanisms of the hydrogen quantum state in both disordered and polycrystalline systems. The remarkable findings of this study establis...

  16. Experimental Study of the Freezing Point of γ-Al2O3/Water Nanofluid

    Directory of Open Access Journals (Sweden)

    Thierry Maré

    2012-01-01

    Full Text Available Nanofluids are colloidal suspensions made of nanometer-sized particles dispersed in a conventional fluid. Their unusual thermal properties explain intensive investigations for several thermal and industrial applications. In this work, an experimental investigation was performed to measure the freezing point and to study the supercooling point made of alumina γ-Al2O3 nanoparticles with 30 nm diameter size and deionized water. Particles' volume fraction used in this work is ranging from 1% to 4%. The T-historic method based on the measurement of the point of inflexion was performed to measure the thermal properties such as the freezing point and the latent heat of solidification of the nanofluids for different concentrations. The results show that the supercooling degree decreases for the high particles volume concentrations and that the agglomeration does not influence the temperature of the freezing point. However, it makes the freezing process longer.

  17. Study on the physiology of diapause, cold hardiness and supercooling point of overwintering pupae of the pistachio fruit hull borer, Arimania comaroffi.

    Science.gov (United States)

    Bemani, Marjan; Izadi, Hamzeh; Mahdian, Kamran; Khani, Abbas; Amin Samih, Mohammad

    2012-07-01

    The pistachio fruit hull borer, Arimania comaroffi (Ragonot) (Lepidoptera: Pyralidae), is a key pest of pistachio orchards in Iran. This pest passes the winter as diapausing pupae. In this study, some physiological changes in relation to environmental temperature were investigated in field collected pupae. The relationship between supercooling point, cold hardiness and physiological changes of a wild population of this pest was also investigated. The glycogen content decreased with decrease in environmental temperature. Decrease in glycogen content was proportional to increase in total body sugar, trehalose, myo-inositol and sorbitol contents. In January with mean ambient temperature of 5.4°C, glycogen (5 mg/g fresh body weight) content was at the lowest level whereas total body sugar (10.3 mg/g fresh body weight), trehalose (8.6 mg/g fresh body weight), myo-inositol (5.3 mg/g fresh body weight) and sorbitol (2.6 mg/g fresh body weight) were at the highest levels. Total body sugar, trehalose, myo-inositol and sorbitol contents increased as mean temperature decreased from 22.7°C in October to 5.4°C in January. Total body lipid decreased during overwintering and reached to the lowest level at the end of March. Supercooling points were decreased from October to January and reached to the lowest level (-16°C) in January with minimum ambient temperature of -10°C. Survival at low temperature after 24 h was also greatest in January with 72% survival at -10°C, 39% survival at -15°C and 0% survival at -20°C. Increase in temperature from February onward, was proportional with increase in supercooling points and decrease in survival rate. Regardless of sampling date, all pupae died after 24 h at -20°C, whereas none pupae died after 24 h at -5°C. This indicates that this insect is freeze-intolerant.

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

    Science.gov (United States)

    Eugene Stanley, H.

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

  19. Glass-forming ability of TeO{sub 2} and temperature induced changes on the structure of the glassy, supercooled, and molten states

    Energy Technology Data Exchange (ETDEWEB)

    Kalampounias, A. G., E-mail: angelos@chemeng.upatras.gr [Department of Chemistry, University of Ioannina, GR-45110 Ioannina (Greece); Institute of Chemical Engineering Sciences (FORTH-ICE/HT), Foundation for Research and Technology Hellas, P.O. Box 1414, GR-26504 Patras (Greece); Tsilomelekis, G.; Boghosian, S. [Department of Chemical Engineering, University of Patras, P.O. Box 1414, GR-26504 Patras (Greece); Institute of Chemical Engineering Sciences (FORTH-ICE/HT), Foundation for Research and Technology Hellas, P.O. Box 1414, GR-26504 Patras (Greece)

    2015-04-21

    Polarized (VV) and depolarized (VH) Raman spectra are obtained for glassy, supercooled, and molten TeO{sub 2} at temperatures up to 1000 K in order to elucidate the temperature evolution of the pertinent structural and vibrational properties. The intrinsic tendency of the system for crystallization is avoided by means of a newly applied protocol, thereby enabling the recording of Raman spectra of pure TeO{sub 2} on going from the molten to the supercooled liquid and to the room temperature glass states. Following an appropriate fitting procedure, the revealed bands are assigned to specific modes of structural polymorphs. A weak polarised band at ∼880 cm{sup −1} is assigned to Te=O terminal stretching in agreement with the literature ab initio molecular orbital calculations. Subtle changes to the relative band intensities within the 550-900 cm{sup −1} stretching region are caused by temperature increase. The network-like structure of the glass/melt is composed by TeO{sub 4} trigonal bipyramid and TeO{sub 3} trigonal pyramid units. With increasing temperature, TeO{sub 4} units convert to TeO{sub 3} units with a concurrent increase in the number of Te=O sites resulting from cleavages within the network structure. The fraction of such terminal oxygen atoms has been directly estimated from the spectroscopic data. The relative populations of the basic building blocks and the average number of O atoms around Te have been estimated for a wide temperature range directly from the Raman spectra, implying a gradual transformation of TeO{sub 4/2} to TeO{sub 2/2}(= O) trigonal pyramid units. The results are discussed in the context of the current phenomenological and theoretical status of the field.

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

    Science.gov (United States)

    Schirò, Giorgio; Fomina, Margarita; Cupane, Antonio

    2013-09-01

    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.

  1. High-Throughput Typing Method To Identify a Non-Outbreak-Involved Legionella pneumophila Strain Colonizing the Entire Water Supply System in the Town of Rennes, France ▿ †

    Science.gov (United States)

    Sobral, D.; Le Cann, P.; Gerard, A.; Jarraud, S.; Lebeau, B.; Loisy-Hamon, F.; Vergnaud, G.; Pourcel, C.

    2011-01-01

    Two legionellosis outbreaks occurred in the city of Rennes, France, during the past decade, requiring in-depth monitoring of Legionella pneumophila in the water network and the cooling towers in the city. In order to characterize the resulting large collection of isolates, an automated low-cost typing method was developed. The multiplex capillary-based variable-number tandem repeat (VNTR) (multiple-locus VNTR analysis [MLVA]) assay requiring only one PCR amplification per isolate ensures a high level of discrimination and reduces hands-on and time requirements. In less than 2 days and using one 4-capillary apparatus, 217 environmental isolates collected between 2000 and 2009 and 5 clinical isolates obtained during outbreaks in 2000 and 2006 in Rennes were analyzed, and 15 different genotypes were identified. A large cluster of isolates with closely related genotypes and representing 77% of the population was composed exclusively of environmental isolates extracted from hot water supply systems. It was not responsible for the known Rennes epidemic cases, although strains showing a similar MLVA profile have regularly been involved in European outbreaks. The clinical isolates in Rennes had the same genotype as isolates contaminating a mall's cooling tower. This study further demonstrates that unknown environmental or genetic factors contribute to the pathogenicity of some strains. This work illustrates the potential of the high-throughput MLVA typing method to investigate the origin of legionellosis cases by allowing the systematic typing of any new isolate and inclusion of data in shared databases. PMID:21821761

  2. Role of water vapor desublimation in the adhesion of an iced droplet to a superhydrophobic surface.

    Science.gov (United States)

    Boinovich, Ludmila; Emelyanenko, Alexandre M

    2014-10-28

    The study of the adhesion of solid and liquid aqueous phases to superhydrophobic surfaces has become an attractive topic for researchers in various fields as a vital step in the design of icephobic coatings. The analysis of the available results shows that the experimentally measured values of adhesion strength for superhydrophobic substrates, which in some cases are quite small, are still essentially higher than might be expected from the portion of the actual wetted area. In this study we have considered the peculiarities of the three-phase contact zone between sessile supercooled water or ice droplets and a superhydrophobic coating at negative temperatures (below 0 °C) and during the water-ice phase transition. Two types of superhydrophobic coatings with very different textures were used to analyze the evolution of shape parameters of a sessile water droplet during droplet cooling and freezing. It was shown that the evolution of the contact angle and droplet contact diameter of a water droplet deposited on a superhydrophobic surface does not undergo essential changes when the droplet is cooled simultaneously with the substrate and the surrounding environment, and the humidity is maintained close to 100% during the cooling process. However, the phase transition from supercooled water to ice droplets leads to the growth of a metastable iced meniscus and a frost halo in the vicinity of the three-phase contact zone. The meniscus effectively increases the area of adhesive contact between the droplet and the substrate. This phenomenon is intrinsically related to the release of the heat of crystallization and is responsible for the enhancement of adhesion to a superhydrophobic substrate upon droplet transition from supercooled water to ice. At the same time, it was shown that the metastable state of the above meniscus leads to its spontaneous sublimation during exposure at negative temperatures.

  3. Freezing phenomena in ice-water systems

    Energy Technology Data Exchange (ETDEWEB)

    Akyurt, M.; Zaki, G.; Habeebullah, B. [Fakieh Center for Applied Research, Makkah Al-Mukarramah (Saudi Arabia); King Abdulaziz University, Jeddah (Saudi Arabia). Dept. of Mechanical Engineering

    2002-09-01

    The characteristics of solidification and melting are reviewed. The properties of water and ice and the phase diagram of water are discussed with special emphasis on ice density. A concise account of the freezing process and the Stefan problem is presented. To this end, the four stages of freezing are identified, supercooling, nucleation and the formation of dendritic ice, the growth of concentric rings of solid ice at 0{sup o}C and the final cooling of the solid ice are treated in some detail. The subject of bursting of pipes is given particular emphasis. Attention is drawn to a common misconception on pipe bursting and to misleading relationships for the computation of freezing time for ice blockage. Several current applications of melting and freezing systems are outlined. (author)

  4. Effectiveness of citizen involvement

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, L. [Prince William Sound Regional Citizen' s Advisory Council, Anchorage, AK (United States)

    2006-07-01

    This paper reviewed the rise of citizen involvement in industry that affects their community. Following the Exxon Valdez oil spill (EVOS) in 1989, the Oil Pollution Act of 1990 provided funding by industry for a citizens group to provide oversite of the Alyeska Pipeline Service Agency terminal and associated tankers. That role is currently filled by the Prince William Sound Regional Citizen's Advisory Council, a volunteer organization that represents communities that were affected by the EVOS. The history of the Prince William Sound Regional Citizen's Advisory Council was discussed along with its structure, funding and overview of projects and research into safer transportation of oil, better oil spill response capabilities and improved environmental protection practices. Some of the successes involving citizen input include the requirement that all tankers going into Prince William Sound be double hull by 2015; a world-class system of tugs escorting tankers in Prince William Sound; installation of an ice-detection radar on a small island near the site of the EVOS; a guidebook for communities affected by man-made disasters; identification of nearshore locations that should be the first to be protected in the case of another spill; and, the installation of a system to capture crude oil vapors when tankers take on cargo. Other projects underway include the study of invasive species that can be transported in the ballast water of tankers, efficacy of dispersants, soil contamination at the tanker loading site, emissions of hazardous air pollutants from ballast water treatment processes, and continual review of emergency response plans. In the 17 years since the formation of the Prince William Sound Regional Citizen's Advisory Council, it has been shown that communication and transparency are the keys to solving complacency, which is believed to have been a contributing factor to the EVOS. 3 refs.

  5. Some considerations on the transport properties of water-glycerol suspensions

    Science.gov (United States)

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

    2016-01-01

    We study the self-diffusion coefficient and viscosity of a water-glycerol mixture for several glycerol molar fractions as a function of temperature well inside the metastable supercooled regime. We perform NMR experiments and verify that the system has at different concentration a fragile-to-strong crossover accompanied by the violation of the Stokes-Einstein relation. We observe that the crossover temperature depends on the water amount. Studying the fractional representation of the Stokes-Einstein relation, we find that in these systems dynamical arrest does not exhibit criticality and the transport parameters have a universal behavior.

  6. Eye Involvement in TSC

    Science.gov (United States)

    ... Privacy Policy Sitemap Learn Engage Donate About TSC Eyes Campbell (1905) first described the eye involvement in ... some form of eye involvement. Nonretinal and Retinal Eye Findings Facial angiofibromas may involve the eyelids of ...

  7. Prospects of the dynamic ice-making technique by supercooled water%过冷水动态制冰技术的应用前景

    Institute of Scientific and Technical Information of China (English)

    郭温芳; 郝长生

    2005-01-01

    阐述了国内外过冷水动态制冰技术的发展情况,并介绍了几种主要的制冰技术.通过分析不同制冰技术的优缺点,论证了过冷水动态制冰技术具有较高的制冰率和能量效率.最后,通过分析过冷水动态制冰的原理,展示了过冷水动态制冰技术的应用前景.

  8. 过冷水动态冰晶制取的实验研究%EXPERIMENTAL STUDY ON DYNAMIC ICE-MAKING BY SUPERCOOLED WATER

    Institute of Scientific and Technical Information of China (English)

    柳飞; 何国庚; 成维

    2005-01-01

    本文提供了一种过冷水动态制取冰晶的实验装置,着重介绍了系统的设计过程以及各部分的技术要求.为保证系统稳定运行,本实验装置采取了一系列措施,包括冰晶消除、过冷解除以及防冻结策略等.实验采用自来水、纯水、6%的乙二醇溶液作为试样,在不同的冷却速率、速度以及壁面条件下进行了对比实验,并给出了定性分析.

  9. Who and What Does Involvement Involve?

    DEFF Research Database (Denmark)

    Hansen, Jeppe Oute; Petersen, Anders; Huniche, Lotte

    2015-01-01

    elucidates how a psycho-ideological discourse positions the mentally ill person as weak, incapable, and ineffective. By contrast, the supporting relative is positioned as a strong, capable, and effective co-therapist. Furthermore, the analysis considers how this dominant discourse of involvement...... theoretical perspective laid out by Ernesto Laclau and Chantal Mouffe, the aim of this study is to show how the dominant discourse about involvement at the political and clinical sites is constituted by understandings of mentally ill individuals and by political objectives of involvement. The analysis...... the responsibility toward the mental health of the ill individual as well as toward the psychological milieu of the family....

  10. NMR spectroscopy study of local correlations in water

    Science.gov (United States)

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

    2016-12-01

    Using nuclear magnetic resonance we study the dynamics of the hydrogen bond (HB) sub-domains in bulk and emulsified water across a wide temperature range that includes the supercooled regime. We measure the proton spin-lattice T1 and spin-spin T2 relaxation times to understand the hydrophilic interactions that determine the properties of water. We use (i) the Bloembergen, Purcell, and Pound approach that focuses on a single characteristic correlation time τc, and (ii) the Powles and Hubbard approach that measures the proton rotational time τθ. We find that when the temperature is low both relaxation times are strongly correlated when the HB lifetime is long, and that when the temperature is high a decrease in the HB lifetime destroys the water clusters and decouples the dynamic modes of the system.

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

    Science.gov (United States)

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

    2016-05-26

    It is a challenging issue to quantitatively characterize how the solute and pressure affect the homogeneous ice nucleation in a supercooled solution. By measuring the glass transition behavior of solutions, a universal feature of water-content dependence of glass transition temperature is recognized, which can be used to quantify hydration water in solutions. The amount of free water can then be determined for water-rich solutions, whose mass fraction, Xf, is found to serve as a universal relevant parameter for characterizing the homogeneous ice nucleation temperature, the meting temperature of primary ice, and even the water activity of solutions of electrolytes and smaller organic molecules. Moreover, the effects of hydrated solute and pressure on ice nucleation is comparable, and the pressure, when properly scaled, can be incorporated into the universal parameter Xf. These results help establish the decisive role of free water in determining ice nucleation and other relevant properties of aqueous solutions.

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

    Science.gov (United States)

    Limmer, David T.; Chandler, David

    2013-06-01

    This paper extends our earlier studies of free energy functions of density and crystalline order parameters for models of supercooled water, which allows us to examine the possibility of two distinct metastable liquid phases [D. T. Limmer and D. Chandler, J. Chem. Phys. 135, 134503 (2011), 10.1063/1.3643333 and preprint arXiv:1107.0337 (2011)]. Low-temperature reversible free energy surfaces of several different atomistic models are computed: mW water, TIP4P/2005 water, Stillinger-Weber silicon, and ST2 water, the last of these comparing three different treatments of long-ranged forces. In each case, we show that there is one stable or metastable liquid phase, and there is an ice-like crystal phase. The time scales for crystallization in these systems far exceed those of structural relaxation in the supercooled metastable liquid. We show how this wide separation in time scales produces an illusion of a low-temperature liquid-liquid transition. The phenomenon suggesting metastability of two distinct liquid phases is actually coarsening of the ordered ice-like phase, which we elucidate using both analytical theory and computer simulation. For the latter, we describe robust methods for computing reversible free energy surfaces, and we consider effects of electrostatic boundary conditions. We show that sensible alterations of models and boundary conditions produce no qualitative changes in low-temperature phase behaviors of these systems, only marginal changes in equations of state. On the other hand, we show that altering sampling time scales can produce large and qualitative non-equilibrium effects. Recent reports of evidence of a liquid-liquid critical point in computer simulations of supercooled water are considered in this light.

  13. Phase behaviour in water/hydrocarbon mixtures involved in gas production systems; etude des equilibres des systemes: eau-hydrocarbures-gaz acides dans le cadre de la production de gaz

    Energy Technology Data Exchange (ETDEWEB)

    Chapoy, A.

    2004-11-15

    Inside wells, natural gases frequently coexist with water. The gases are in equilibrium with the sub-adjacent aquifer. Many problems are associated with the presence of water during the production, transport and processing of natural gases. Accurate knowledge of the thermodynamic properties of the water/hydrocarbon and water-inhibitor/hydrocarbon equilibria near the hydrate forming conditions, at sub-sea pipeline conditions and during the transport is crucial for the petroleum industry. An apparatus based on a static/analytic method combined with a dilutor apparatus to calibrate on the gas chromatograph (GC) detectors with water was used to measure the water content of binary systems (i.e.: water - methane, ethane - water, nitrogen - water...) as well of a synthetic hydrocarbon gas mixture (i.e.: 94% methane, 4% ethane and 2% n-butane) with and without inhibitor. This same apparatus was also used generate data of methane, ethane, propane, n-butane and nitrogen solubility in water and also the solubilities of a synthetic mixture in water. In-house software has been developed in order to fit and model the experimental data. (author)

  14. Structural features and the microscopic dynamics of the three-component Zr47Cu46Al7 system: Equilibrium melt, supercooled melt, and amorphous alloy

    Science.gov (United States)

    Khusnutdinoff, R. M.; Mokshin, A. V.; Klumov, B. A.; Ryltsev, R. E.; Chtchelkatchev, N. M.

    2016-08-01

    The structural and dynamic properties of the three-component Zr47Cu46Al7 system are subjected to a molecular dynamics simulation in the temperature range T = 250-3000 K at a pressure p = 1.0 bar. The temperature dependences of the Wendt-Abraham parameter and the translation order parameter are used to determine the glass transition temperature in the Zr47Cu46Al7 system, which is found to be T c ≈ 750 K. It is found that the bulk amorphous Zr47Cu46Al7 alloy contains localized regions with an ordered atomic structures. Cluster analysis of configuration simulation data reveals the existence of quasi-icosahedral clusters in amorphous metallic Zr-Cu-Al alloys. The spectral densities of time radial distribution functions of the longitudinal ( C˜ L( k, ω)) and transverse ( C˜ T ( k, ω)) fluxes are calculated in a wide wavenumber range in order to study the mechanisms of formation of atomic collective excitations in the Zr47Cu46Al7 system. It was found that a linear combination of three Gaussian functions is sufficient to reproduce the ( C˜ L ( k, ω)) spectra, whereas at least four Gaussian contributions are necessary to exactly describe the ( C˜ T ( k, ω)) spectra of the supercooled melt and the amorphous metallic alloy. It is shown that the collective atomic excitations in the equilibrium melt at T = 3000 K and in the amorphous metallic alloy at T = 250 K are characterized by two dispersion acoustic-like branches related with longitudinal and transverse polarizations.

  15. Lung Involvement in TSC

    Science.gov (United States)

    ... Privacy Policy Sitemap Learn Engage Donate About TSC Lungs Lung involvement in tuberous sclerosis complex (TSC) has ... testing. (Krueger et al., 2013) What Are the Lung Features of TSC? Two forms of lung involvement ...

  16. Practical Use Study of the Direct Conveyance and Cooling System for Iced Water by the Propylene Glycol Solutio

    Science.gov (United States)

    Seki, Mitsuo; Ninomiya, Tohru; Matsubara, Kazuo; Aikawa, Keisuke; Ikoma, Kenji

    In a cold storage warehouse, by developing the thermal energy storage technique using cheap electric powerin the night, it is necessary to construct a high-efficient and energy-saving-type refrigeration system in which air conditioning is possible at 0 degrees c. We created a brine iced water (ice slurry) cooled under 0 degreesc by a closed supercooling ice making method. For a practical application, the brine iced water was directly sent to the load side, and it was utilized as the secondary refrigerant for the heat exchange. As a result, by replacing the pure water with a marketed propylene glycol solution, it was proven that the conventional closed supercooling ice making method could be similarly utilized for the ice making. However, it is necessary to control the evaporation temperature in the refrigerator, because the freezing temperature changes with the brine concentration. In the refrigerator entrance, it is necessary to heat at a constant temperature so that the inflow brine may not freeze. In case of the brine iced water, the fluidity of the brine iced water is high, and the ice particle is carried away by the flow. Therefore, it is necessary to prevent runoff of the ice particle from an intake of the thermal storage tank in case of thebrine water. This proposal system was confirmed that there was practically no problem by an operation of a 15kW refrigerator system.

  17. The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results

    Science.gov (United States)

    Mallamace, F.; Broccio, M.; Corsaro, C.; Faraone, A.; Wanderlingh, U.; Liu, L.; Mou, C.-Y.; Chen, S. H.

    2006-04-01

    By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature TL=223±2K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1/D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time ⟨τT⟩, as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.

  18. Recrystallization of freezable bound water in aqueous solutions of medium concentration

    Science.gov (United States)

    Lishan, Zhao; Liqing, Pan; Ailing, Ji; Zexian, Cao; Qiang, Wang

    2016-07-01

    For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings difficulty to application and misleads the interpretation of relevant experiments. Here, we report a quantification scheme for the freezable bound water based on the water-content dependence of glass transition temperature, by which also the concentration range for the solutions that may undergo recrystallization finds a clear definition. Furthermore, we find that depending on the amount of the freezable bound water, different temperature protocols should be devised to achieve a complete recrystallization. Our results may be helpful for understanding the dynamics of supercooled aqueous solutions and for improving their manipulation in various industries. Project supported by the Knowledge Innovation Project of Chinese Academy of Sciences on Water Science Research (Grant No. KJZD-EW-M03) and the National Natural Science Foundation of China (Grant Nos. 11474325 and 11290161).

  19. Dual spectrum neutron radiography: identification of phase transitions between frozen and liquid water.

    Science.gov (United States)

    Biesdorf, J; Oberholzer, P; Bernauer, F; Kaestner, A; Vontobel, P; Lehmann, E H; Schmidt, T J; Boillat, P

    2014-06-20

    In this Letter, a new approach to distinguish liquid water and ice based on dual spectrum neutron radiography is presented. The distinction is based on arising differences between the cross section of water and ice in the cold energy range. As a significant portion of the energy spectrum of the ICON beam line at Paul Scherrer Institut is in the thermal energy range, no differences can be observed with the entire beam. Introducing a polycrystalline neutron filter (beryllium) inside the beam, neutrons above its cutoff energy are filtered out and the cold energy region is emphasized. Finally, a contrast of about 1.6% is obtained with our imaging setup between liquid water and ice. Based on this measurement concept, the temporal evolution of the aggregate state of water can be investigated without any prior knowledge of its thickness. Using this technique, we could unambiguously prove the production of supercooled water inside fuel cells with a direct measurement method.

  20. The fragile-to-strong dynamic crossover transition in confined water: nuclear magnetic resonance results.

    Science.gov (United States)

    Mallamace, F; Broccio, M; Corsaro, C; Faraone, A; Wanderlingh, U; Liu, L; Mou, C-Y; Chen, S H

    2006-04-28

    By means of a nuclear magnetic resonance experiment, we give evidence of the existence of a fragile-to-strong dynamic crossover transition (FST) in confined water at a temperature T(L)=223+/-2 K. We have studied the dynamics of water contained in 1D cylindrical nanoporous matrices (MCM-41-S) in the temperature range 190-280 K, where experiments on bulk water were so far hampered by crystallization. The FST is clearly inferred from the T dependence of the inverse of the self-diffusion coefficient of water (1D) as a crossover point from a non-Arrhenius to an Arrhenius behavior. The combination of the measured self-diffusion coefficient D and the average translational relaxation time tau(T), as measured by neutron scattering, shows the predicted breakdown of Stokes-Einstein relation in deeply supercooled water.

  1. The anomalous behavior of the density of water in the range 30 K < T < 373 K.

    Science.gov (United States)

    Mallamace, Francesco; Branca, Caterina; Broccio, Matteo; Corsaro, Carmelo; Mou, Chung-Yuan; Chen, Sow-Hsin

    2007-11-20

    The temperature dependence of the density of water, rho(T), is obtained by means of optical scattering data, Raman and Fourier transform infrared, in a very wide temperature range, 30 < T < 373 K. This interval covers three regions: the thermodynamically stable liquid phase, the metastable supercooled phase, and the low-density amorphous solid phase, at very low T. From analyses of the profile of the OH stretching spectra, we determine the fractional weight of the two main spectral components characterized by two different local hydrogen bond structures. They are, as predicted by the liquid-liquid phase transition hypothesis of liquid water, the low- and the high-density liquid phases. We evaluate contributions to the density of these two phases and thus are able to calculate the absolute density of water as a function of T. We observe in rho(T) a complex thermal behavior characterized not only by the well known maximum in the stable liquid phase at T = 277 K, but also by a well defined minimum in the deeply supercooled region at 203 +/- 5 K, in agreement with suggestions from molecular dynamics simulations.

  2. Effect of strain on ferrite transformation from super-cooled austenite in Fe-0. 5%C alloy. Fe-0. 5%C gokin no karei osutenaito/feraito hentai ni oyobosu kako no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, K.; Ito, Y.; Narita, T. (Hokkaido Univ., Sapporo (Japan). Faculty of Engineering)

    1993-08-01

    During the cooling of a steel, when austenite is applied by strain, the temperature of ferrite transformation would increase accompanied with decrease of its given temperature and increase of strain. In this study, the isothermal transformation behaviour from austenite to ferrite applied by strain in the super-cooled state was investigated, effect of strain on size of ferrite particles and increase of volume rate during transformation were explained by using the velocity theory. That is, concerning to the alloy of two-elemental system Fe-0.51%C cooled at 0.3[degree]C/s and applied by strain at 710[degree]C, at which austenite was super-cooled by 55[degree]C, its isothermal transformation behaviour was investigated. As a result, the following conclusions were obtained. Time required for the transformation remarkably decreased and the size of ferrite particles became ultra-fine subjected to strain. The nucleation rate of ferrite particles remarkably increased with increasing strain. 14 refs., 11 figs., 1 tab.

  3. Deterioration of materials involving hydraulic binders in water-saturated media. Application to long-term concrete packaging; Degradation des materiaux a base de liants hydrauliques en milieu sature. Application au comportement a long terme des colis ''beton''

    Energy Technology Data Exchange (ETDEWEB)

    Le Bescop, P.; Adenot, F.; Galle, C.; Lovera, P. [CEA/Saclay, Dept. d' Entroposage et de Stockage des Dechets (DESD), 91 - Gif-sur-Yvette (France); CEA/Cadarache, Dept. d' Entreposage et de Stockage des Dechets, DESD, 13 - Saint-Paul-lez-Durance (France)

    2000-07-01

    The behaviour of a concrete container of radioactive wastes has to be studied according to its surroundings. Schematically we can distinguish 2 stages in the evolution of a concrete packaging: first, the evolution in an unsaturated open system (wet gaseous atmosphere) and secondly the evolution in an open system saturated with water. This article deals with the second stage. 3 likely deterioration factors are reviewed: 1) chemical damage under water, these damage involve a series of dissolution-reprecipitation processes; 2) the carbonation under water which depends strongly on the concentration of carbonates in natural water, this process can lead to a loss of porosity; and 3) the action of sulfate ions to which we can associate the apparition of mineral phases capable of fissuring materials. The modelling of these 3 interactions combined with a radionuclide transport model will allow us to evaluate the confining property of concrete containers. (A.C.)

  4. Doctors' involvement in torture

    DEFF Research Database (Denmark)

    Sonntag, Jesper

    2008-01-01

    Doctors from both non-democratic and democratic countries are involved in torture. The majority of doctors involved in torture are doctors at risk. Doctors at risk might compromise their ethical duty towards patients for the following possible reasons: individual factors (such as career, economic...

  5. Recrystallization of freezable bound water in aqueous solutions of medium concentrations

    Institute of Scientific and Technical Information of China (English)

    赵立山; 潘礼庆; 纪爱玲; 曹则贤; 王强

    2016-01-01

    For aqueous solutions with freezable bound water, vitrification and recrystallization are mingled, which brings diffi-culty to application and misleads the interpretation of relevant experiments. Here, we report a quantification scheme for the freezable bound water based on the water-content dependence of glass transition temperature, by which also the concentra-tion range for the solutions that may undergo recrystallization finds a clear definition. Furthermore, we find that depending on the amount of the freezable bound water, different temperature protocols should be devised to achieve a complete recrys-tallization. Our results may be helpful for understanding the dynamics of supercooled aqueous solutions and for improving their manipulation in various industries.

  6. The glass-liquid transition of water on hydrophobic surfaces.

    Science.gov (United States)

    Souda, Ryutaro

    2008-09-28

    Interactions of thin water films with surfaces of graphite and vitrified room-temperature ionic liquid [1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)])] were investigated using time-of-flight secondary ion mass spectrometry as a function of temperature and annealing time to elucidate the glass-liquid transition of water at the molecular level. Surface diffusion of water occurs at temperatures higher than 120 K, thereby forming three-dimensional clusters (a two-dimensional layer) on the [bmim][PF(6)] (graphite) surface. The hydrophobic effect of the surface decreases with increasing coverage of water; the bulklike properties evolve up to 40 ML, as evidenced by the occurrence of film dewetting at around the conventional glass transition temperature (140 K). Results also showed that aging is necessary for the water monolayer (a 40 ML water film) to dewet the graphite ([bmim][PF(6)]) surface. The occurrence of aging is explainable by the successive evolution of two distinct liquids during the glass-liquid transition: low density liquid is followed by supercooled liquid water. The water monolayer on graphite is characterized by the preferred orientation of unpaired OH groups toward the surface; this structure is arrested during the aging time despite the occurrence of surface diffusion. However, the water monolayer formed on the [bmim][PF(6)] surface agglomerates immediately after the commencement of surface diffusion. The structure of low density liquid tends to be arrested by the attractive interaction with the neighbors.

  7. Thermodynamics of ice nucleation in liquid water.

    Science.gov (United States)

    Wang, Xin; Wang, Shui; Xu, Qinzhi; Mi, Jianguo

    2015-01-29

    We present a density functional theory approach to investigate the thermodynamics of ice nucleation in supercooled water. Within the theoretical framework, the free-energy functional is constructed by the direct correlation function of oxygen-oxygen of the equilibrium water, and the function is derived from the reference interaction site model in consideration of the interactions of hydrogen-hydrogen, hydrogen-oxygen, and oxygen-oxygen. The equilibrium properties, including vapor-liquid and liquid-solid phase equilibria, local structure of hexagonal ice crystal, and interfacial structure and tension of water-ice are calculated in advance to examine the basis for the theory. The predicted phase equilibria and the water-ice surface tension are in good agreement with the experimental data. In particular, the critical nucleus radius and free-energy barrier during ice nucleation are predicted. The critical radius is similar to the simulation value, suggesting that the current theoretical approach is suitable in describing the thermodynamic properties of ice crystallization.

  8. Consumer Involvement in Rehabilitation

    Science.gov (United States)

    Daniels, Susan

    1976-01-01

    With the emphasis on consumer involvement in the Rehabilitation Act of 1973, changes in the counseling relationship must occur. This article discusses new interaction patterns for consumer and counselor. (Author)

  9. Clinical studies involving probiotics

    OpenAIRE

    Degnan, Fred H

    2012-01-01

    Researchers from a diverse array of scientific disciplines have focused and continue to focus on opportunities and areas for responsible clinical research involving the possible beneficial health effects of “probiotics.” Investigators and researchers should be aware that not all clinical research involving probiotics reasonably falls within the requirements of the “investigational new drug” (IND) rubric administered and enforced by the US Food and Drug Administration. In determining whether a...

  10. Design of ice-free nanostructured surfaces based on repulsion of impacting water droplets.

    Science.gov (United States)

    Mishchenko, Lidiya; Hatton, Benjamin; Bahadur, Vaibhav; Taylor, J Ashley; Krupenkin, Tom; Aizenberg, Joanna

    2010-12-28

    Materials that control ice accumulation are important to aircraft efficiency, highway and powerline maintenance, and building construction. Most current deicing systems include either physical or chemical removal of ice, both energy and resource-intensive. A more desirable approach would be to prevent ice formation rather than to fight its build-up. Much attention has been given recently to freezing of static water droplets resting on supercooled surfaces. Ice accretion, however, begins with the droplet/substrate collision followed by freezing. Here we focus on the behavior of dynamic droplets impacting supercooled nano- and microstructured surfaces. Detailed experimental analysis of the temperature-dependent droplet/surface interaction shows that highly ordered superhydrophobic materials can be designed to remain entirely ice-free down to ca. -25 to -30 °C, due to their ability to repel impacting water before ice nucleation occurs. Ice accumulated below these temperatures can be easily removed. Factors contributing to droplet retraction, pinning and freezing are addressed by combining classical nucleation theory with heat transfer and wetting dynamics, forming the foundation for the development of rationally designed ice-preventive materials. In particular, we emphasize the potential of hydrophobic polymeric coatings bearing closed-cell surface microstructures for their improved mechanical and pressure stability, amenability to facile replication and large-scale fabrication, and opportunities for greater tuning of their material and chemical properties.

  11. Research on the Necessity and Method of Beverage Companies Involved in Water Management%饮料企业参与水管理的必要性及方法研究

    Institute of Scientific and Technical Information of China (English)

    闻万隆; 张寒茜

    2014-01-01

    在全球和中国水危机的大背景下,企业和公民社会共同面临复杂多样的水问题。饮料企业属于用水密集型行业,水是最大宗的原材料,因此来自水的挑战尤其突出。由于很多风险源自外部,仅仅关注内部要素(例如生产线、工厂、办公室)并不足以消减与水相关的商业风险。富有远见的饮料企业将走出公司大门,把目光投向更广阔的领域,采取更加积极的态度和富有创新性的手段参与水管理。本文分析了饮料企业参与水管理的社会大背景、动机、尺度和方式以及注意事项。呼吁饮料企业探求一条既有益于商业目标同时又为社会添福祉的道路。%Given that both the world and China are experiencing water crisis, private sectors and the general public are confronted by various complicated water issues. One of the most prominent challenges faced by the beverage companies is water. These companies are in significant water-using sectors, with water as the top one raw material. Since a lot of risks are from external sources, it is not enough to mitigate business risks by only focusing on internal elements. In the future, beverage companies with vision will go beyond the factory gate, and participate in water management in a more active and creative way. This paper analyzes social background and motivation behind the corporateinvolvement in water management, as well as optional scale, approaches and things to be considered in execution. Beverage companies need to find a way to meet its business goals while at the same time benefit the general society.

  12. Pancreatic Involvement in Melioidosis

    Directory of Open Access Journals (Sweden)

    Vui Heng Chong

    2010-07-01

    Full Text Available Context Melioidosis is endemic to tropical regions and, despite the common occurrence of intra-abdominal abscesses, pancreatic involvement in melioidosis has not previously been reported. Objective We report our experience with pancreatic melioidosis. Patients All 65 patients treated for melioidosis who had computed tomography (CT scans were identified from prospective databases and were retrospectively reviewed. Main outcome measures A detailed review of cases with pancreas involvement was carried out. Results There were four cases (three males and one female; median age 29.5 years, range: 25-48 years with pancreatic melioidosis, giving a prevalence of 6.2%. All had predisposing conditions (two had poorly controlled diabetes mellitus and two had thalassemia for melioidosis. Fever (100%, anorexia (100%, weight loss (100%, rigor (75% and abdominal pain (75% were the most common symptoms at presentation and the median duration of symptoms before presentation was six weeks (range: 2-8 weeks. All pancreatic abscesses were detected on CT scan. Multiple foci involvement was common (3 to 6 sites: blood (4 patients, liver (3 patients, psoas muscle (2 patients, spleen (2 patients, infected ascites (2 patients and lung (1 patient. Pancreatic involvement ranged from multi-focal micro-abscesses to focal large abscesses and involved all parts of the pancreas (body 100%, head 75% and tail 50%. Associated pancreatic findings included splenic vein thrombosis, peripancreatic inflammation and peripancreatic fat streaking. All the pancreatic abscesses were resolved with antibiotics without requiring pancreatic abscess drainage (including one patient who died from disseminated melioidosis. Conclusion Pancreatic involvement typically occurs as part of multi-organ involvement and commonly manifests as multifoci micro-abscesses. Associated pancreatic abnormalities were also common. All responded to treatment without requiring drainage

  13. [Pulmonary involvements of sarcoidosis].

    Science.gov (United States)

    Ohmichi, M; Hiraga, Y; Hirasawa, M

    1990-01-01

    We reported about intrathoracic changes and prognosis of 686 patients with sarcoidosis diagnosed in our hospital between 1963 and 1988. We evaluated CT findings in 135 patients with sarcoidosis and found pulmonary involvements in 81. We analyzed CT findings according to the classification by Tuengerthal which classified radiographic findings combining ILO classification of pneumoconiosis and characteristic findings of bronchovascular sheath with sarcoidosis. The CT findings were as follows: small opacities (44 out of 81 cases, 54.3%), large opacities (37 cases, 46.7%). Additional findings were as follows: peribronchial marking (42 cases, 51.9%), contraction (17 cases, 21.0%), pleural involvement (9 cases, 11.1%), bulla (5 cases, 6.2%). The characteristic CT findings of serious sarcoidosis were extasis of bronchus, thickening of the bronchial wall, unclearness of vascular shadow, atelectasis and thickening of pleura. Concerning the prognosis of pulmonary involvement, according to age, patients younger than 30 years old at initial diagnosis were better than those of 30 years and over in terms of disappearance of pulmonary involvements. According to stage, patients of stage I and stage II were better than those of stage III. Among the patients we were able to observe chest X-ray findings during five years according to the character of shadow, ill-defined shadow of small opacities and rounded shadows of large opacities had a higher disappearance rate of pulmonary involvements than irregular shadows of large opacities, atelectasis and contraction.

  14. Musculoskeletal involvement in sarcoidosis*, **

    Science.gov (United States)

    Nessrine, Akasbi; Zahra, Abourazzak Fatima; Taoufik, Harzy

    2014-01-01

    Sarcoidosis is a multisystem inflammatory disorder of unknown cause. It most commonly affects the pulmonary system but can also affect the musculoskeletal system, albeit less frequently. In patients with sarcoidosis, rheumatic involvement is polymorphic. It can be the presenting symptom of the disease or can appear during its progression. Articular involvement is dominated by nonspecific arthralgia, polyarthritis, and Löfgren's syndrome, which is defined as the presence of lung adenopathy, arthralgia (or arthritis), and erythema nodosum. Skeletal manifestations, especially dactylitis, appear mainly as complications of chronic, multiorgan sarcoidosis. Muscle involvement in sarcoidosis is rare and usually asymptomatic. The diagnosis of rheumatic sarcoidosis is based on X-ray findings and magnetic resonance imaging findings, although the definitive diagnosis is made by anatomopathological study of biopsy samples. Musculoskeletal involvement in sarcoidosis is generally relieved with nonsteroidal anti-inflammatory drugs or corticosteroids. In corticosteroid-resistant or -dependent forms of the disease, immunosuppressive therapy, such as treatment with methotrexate or anti-TNF-α, is employed. The aim of this review was to present an overview of the various types of osteoarticular and muscle involvement in sarcoidosis, focusing on their diagnosis and management. PMID:24831403

  15. Musculoskeletal involvement in sarcoidosis

    Directory of Open Access Journals (Sweden)

    Akasbi Nessrine

    2014-04-01

    Full Text Available Sarcoidosis is a multisystem inflammatory disorder of unknown cause. It most commonly affects the pulmonary system but can also affect the musculoskeletal system, albeit less frequently. In patients with sarcoidosis, rheumatic involvement is polymorphic. It can be the presenting symptom of the disease or can appear during its progression. Articular involvement is dominated by nonspecific arthralgia, polyarthritis, and Löfgren's syndrome, which is defined as the presence of lung adenopathy, arthralgia (or arthritis, and erythema nodosum. Skeletal manifestations, especially dactylitis, appear mainly as complications of chronic, multiorgan sarcoidosis. Muscle involvement in sarcoidosis is rare and usually asymptomatic. The diagnosis of rheumatic sarcoidosis is based on X-ray findings and magnetic resonance imaging findings, although the definitive diagnosis is made by anatomopathological study of biopsy samples. Musculoskeletal involvement in sarcoidosis is generally relieved with nonsteroidal anti-inflammatory drugs or corticosteroids. In corticosteroid-resistant or -dependent forms of the disease, immunosuppressive therapy, such as treatment with methotrexate or anti-TNF-α, is employed. The aim of this review was to present an overview of the various types of osteoarticular and muscle involvement in sarcoidosis, focusing on their diagnosis and management.

  16. Evidence of low-density and high-density liquid phases and isochore end point for water confined to carbon nanotube.

    Science.gov (United States)

    Nomura, Kentaro; Kaneko, Toshihiro; Bai, Jaeil; Francisco, Joseph S; Yasuoka, Kenji; Zeng, Xiao Cheng

    2017-04-18

    Possible transition between two phases of supercooled liquid water, namely the low- and high-density liquid water, has been only predicted to occur below 230 K from molecular dynamics (MD) simulation. However, such a phase transition cannot be detected in the laboratory because of the so-called "no-man's land" under deeply supercooled condition, where only crystalline ices have been observed. Here, we show MD simulation evidence that, inside an isolated carbon nanotube (CNT) with a diameter of 1.25 nm, both low- and high-density liquid water states can be detected near ambient temperature and above ambient pressure. In the temperature-pressure phase diagram, the low- and high-density liquid water phases are separated by the hexagonal ice nanotube (hINT) phase, and the melting line terminates at the isochore end point near 292 K because of the retracting melting line from 292 to 278 K. Beyond the isochore end point (292 K), low- and high-density liquid becomes indistinguishable. When the pressure is increased from 10 to 600 MPa along the 280-K isotherm, we observe that water inside the 1.25-nm-diameter CNT can undergo low-density liquid to hINT to high-density liquid reentrant first-order transitions.

  17. Involve physicians in marketing.

    Science.gov (United States)

    Randolph, G T; Baker, K M; Laubach, C A

    1984-01-01

    Many everyday problems in medical group practice can be attacked by a marketing approach. To be successful, however, this kind of approach must have the full support of those involved, especially the physicians, since they are the principal providers of healthcare services. When marketing is presented in a broad context, including elements such as patient mix, population distribution, and research, physicians are more likely to be interested and supportive. The members of Geisinger Medical Center's Department of Cardiovascular Medicine addressed their patient appointment backlog problem with a marketing approach. Their method is chronicled here and serves as a fine example of how physician involvement in marketing can lead to a positive outcome.

  18. The interaction of radio frequency electromagnetic fields with atmospheric water droplets and applications to aircraft ice prevention. Thesis

    Science.gov (United States)

    Hansman, R. J., Jr.

    1982-01-01

    The feasibility of computerized simulation of the physics of advanced microwave anti-icing systems, which preheat impinging supercooled water droplets prior to impact, was investigated. Theoretical and experimental work performed to create a physically realistic simulation is described. The behavior of the absorption cross section for melting ice particles was measured by a resonant cavity technique and found to agree with theoretical predictions. Values of the dielectric parameters of supercooled water were measured by a similar technique at lambda = 2.82 cm down to -17 C. The hydrodynamic behavior of accelerated water droplets was studied photograhically in a wind tunnel. Droplets were found to initially deform as oblate spheroids and to eventually become unstable and break up in Bessel function modes for large values of acceleration or droplet size. This confirms the theory as to the maximum stable droplet size in the atmosphere. A computer code which predicts droplet trajectories in an arbitrary flow field was written and confirmed experimentally. The results were consolidated into a simulation to study the heating by electromagnetic fields of droplets impinging onto an object such as an airfoil. It was determined that there is sufficient time to heat droplets prior to impact for typical parameter values. Design curves for such a system are presented.

  19. Reaching Parents Through Involvement

    Science.gov (United States)

    Schmerber, Ronald J.

    1974-01-01

    The parent involvement program evolved from the needs of parents. Basic to the program is the concept of parenting, which implies taking positive action to facilitate and meet the needs of the children ahe family. Parents participate in the development, implementation, and evaluation of their child's program. (Author)

  20. Effect of phase separation induced supercooling on magnetotransport properties of epitaxial La5/8−yPryCa3/8MnO3 (y≈0.4 thin film

    Directory of Open Access Journals (Sweden)

    Sandeep Singh

    2015-02-01

    Full Text Available Thin films of La5/8−yPryCa3/8MnO3 (y≈0.4 have been grown on single crystal SrTiO3 (001 by RF sputtering. The structural and surface characterizations confirm the epitaxial nature of these film. However, the difference between the ω-scan of the (002 and (110 peaks and the presence of pits/holes in the step-terrace type surface morphology suggests high density of defect in these films. Pronounced hysteresis between the field cooled cooling (FCC and field cooled warming (FCW magnetization measurements suggest towards the non-ergodic magnetic state. The origin of this nonergodicity could be traced to the magnetic liquid like state arising from the delicacy of the coexisting magnetic phases, viz., ferromagnetic and antiferromagnetic-charge ordered (FM/AFM-CO. The large difference between the insulator metal transitions during cooling and warming cycles (TIMC ∼ 64 K and TIMW ∼ 123 K could be regarded as a manifestation of the nonergodicity leading to supercooling of the magnetic liquid while cooling. The nonergodicity and supercooling are weakened by the AFM-FM phase transition induced by an external magnetic field. TIM and small polaron activation energy corresponding the magnetic liquid state (cooling cycle vary nonlinearly with the applied magnetic field but become linear in the crystalline solid state (warming cycle. The analysis of the low temperature resistivity data shows that electron-phonon interaction is drastically reduced by the applied magnetic field. The resistivity minimum in the lower temperature region of the self-field warming curve has been explained in terms of the Kondo like scattering in the magnetically inhomogeneous regime.

  1. Microorganisms involved in MIC

    Energy Technology Data Exchange (ETDEWEB)

    Sorensen, K. [Danish Technological Institute (Denmark)

    2011-07-01

    Microbiologically influenced corrosion (MIC) is a widespread problem that is difficult to detect and assess because of its complex mechanism. This paper presents the involvement of microorganisms in MIC. Some of the mechanisms that cause MIC include hydrogen consumption, production of acids, anode-cathode formation and electron shuttling. A classic bio-corrosive microorganism in the oil and gas industry is sulphate-reducing prokaryotes (SRP). Methanogens also increase corrosion rates in metals. Some of the phylogenetic orders detected while studying SRP and methanogens are archaeoglobales, clostridiales, methanosarcinales and methanothermococcus. There were some implications, such as growth of SRP not being correlated with growth of methanogens; methanogens were included in MIC risk assessment. A few examples are used to display how microorganisms are involved in topside corrosion and microbial community in producing wells. From the study, it can be concluded that, MIC risk assessment includes system data and empirical knowledge of the distribution and number of microorganisms in the system.

  2. Involved Node Radiation Therapy

    DEFF Research Database (Denmark)

    Maraldo, Maja V; Aznar, Marianne C; Vogelius, Ivan R

    2012-01-01

    PURPOSE: The involved node radiation therapy (INRT) strategy was introduced for patients with Hodgkin lymphoma (HL) to reduce the risk of late effects. With INRT, only the originally involved lymph nodes are irradiated. We present treatment outcome in a retrospective analysis using this strategy...... to 36 Gy). Patients attended regular follow-up visits until 5 years after therapy. RESULTS: The 4-year freedom from disease progression was 96.4% (95% confidence interval: 92.4%-100.4%), median follow-up of 50 months (range: 4-71 months). Three relapses occurred: 2 within the previous radiation field......, and 1 in a previously uninvolved region. The 4-year overall survival was 94% (95% confidence interval: 88.8%-99.1%), median follow-up of 58 months (range: 4-91 months). Early radiation therapy toxicity was limited to grade 1 (23.4%) and grade 2 (13.8%). During follow-up, 8 patients died, none from HL, 7...

  3. Between Involvement and Detachment

    DEFF Research Database (Denmark)

    Thomasen, Gry

    Between Involvement and Detachment takes grasp with the Johnson administration’s (1963-1969) perceptions of and responses to the Western European realignments. Arguing that the Johnson administration set out to maintain the American unilateralist position in the transatlantic relation, not just a...... the administration maintained. Despite changed circumstances, the Nixon administration’s relation with and perceptions of the European allies largely resemble the traditionalist view of the Johnson administration....

  4. Joint involvement in Ochronosis

    OpenAIRE

    Biehl, Christoph; Thormann, U.; Madera, N.; Heiß, C

    2016-01-01

    Introduction: Ochronosis is a metabolic disorder that is usually associated with the typical brown-black colored urine and retention of phenol complexes in sclera and skin. Kidney and heart are also checked, the disease can also cause damage in these organs. The disease is less associated with degenerative changes in the joints of the limbs and the spine. Methods: We report on the progress of a patient with documented family history on alcaptonuria and joint involvement. In the age of 69 ...

  5. Involvement Without Participation?

    DEFF Research Database (Denmark)

    Olsén, Peter

    2012-01-01

    The article presents a case study of a knowledge-intensive company that launched a 2-year project to improve their psychosocial working environment. All parties agreed on the project, and the methods used aimed to promote the involvement of the employees. Surprisingly, the psychosocial working...... and participation. In order to develop a more sustainable and viable psychosocial working environment, a broader and more democratic notion of organisational learning and managing is proposed....

  6. Getting involved in research.

    Science.gov (United States)

    Banner, Davina; Grant, Lyle G

    2011-01-01

    The need for quality nursing research to promote evidence-based practice and optimize patient care is well recognized. This is particularly pertinent in cardiovascular nursing, where cardiovascular disease continues to be the leading cause of morbidity and mortality worldwide (World Health Organization, 2007). Across the spectrum of academic, clinical, and health care administration nursing roles, research remains fundamental to bridging theory, practice, and education (LoBiondo-Wood, Haber, Cameron, & Singh, 2009). Despite recognition of the importance of nursing research, the gap between research and practice continues to be an ongoing issue (Funk, Tornquist, & Champagne, 1995; Pettengill, Gillies, & Clark, 1994; Rizzuto, Bostrom, Suterm, & Chenitz, 1994; Rolfe, 1998). Nurses are appropriately situated to contribute to research that improves clinical outcomes and health service delivery. However, the majority of nurses in clinical practice do not have a significant research component structured into their nursing role. In this research column, the authors outline the importance of nurses being engaged in research and present some different levels of involvement that nurses may assume. A continuum of nursing research involvement includes asking researchable questions, being a savvy consumer of research evidence, finding your own level of research involvement, and aspiring to lead.

  7. The peculiarities of water crystallization and ice melting processes in the roots of one-year plants (Plantago major L.).

    Science.gov (United States)

    Bakradze, N; Kiziria, E; Sokhadze, V; Gogichaishvili, S

    2008-01-01

    Results are presented of a water phase transition study in plantain (Plantago major L.) roots, which were used as a model system to research the peculiarities of water crystallization and ice melting processes in complex heterogeneous biological systems. It was confirmed that water in such systems is crystallized in two clearly distinguished temperature ranges: -10 to -25 degree capital ES, Cyrillic and -25 to -45 degree capital ES, Cyrillic. These water fractions are conditionally attributed to extracellular (-10 to -25 degree capital ES, Cyrillic) and intracellular (-25 to -45 degree capital ES, Cyrillic) solutions. A possible explanation is given for such significant supercooling of the intracellular solution. The values of osmotic pressures of extra- and intracellular solutions were determined according to ice melting curves. It is noted that the intracellular solution, which crystallized at lower temperatures, had a lower osmotic pressure.

  8. Water, Water Everywhere

    Science.gov (United States)

    Keeler, Rusty

    2009-01-01

    Everybody knows that children love water and how great water play is for children. The author discusses ways to add water to one's playscape that fully comply with health and safety regulations and are still fun for children. He stresses the importance of creating water play that provides children with the opportunity to interact with water.

  9. Water, Water Everywhere

    Science.gov (United States)

    Keeler, Rusty

    2009-01-01

    Everybody knows that children love water and how great water play is for children. The author discusses ways to add water to one's playscape that fully comply with health and safety regulations and are still fun for children. He stresses the importance of creating water play that provides children with the opportunity to interact with water.

  10. Involvement in Physical Activity

    Directory of Open Access Journals (Sweden)

    James Gavin

    2013-04-01

    Full Text Available A total of 1,096 adolescents participated in 123 focus groups regarding the perceived outcomes of their involvement in sports and physical activity (PA. The groups, segmented by grade level, sex, and school types, were conducted in both public and private high schools in Montreal, Quebec. We sought to understand, through the participants’ own words, their perception of the outcome matrix of involvement in sports and PA. Focus group questions emphasized changes that adolescents associated with such engagement. In particular, participants were asked how sports and PA might influence behaviors, emotional states, personal characteristics, and other outcomes. Twelve themes were identified in the responses: Positive Health and Physical Changes (18.5%, Activity-Related Positive Emotions (15.6%, and Personal Learning (11.3% were most prevalent in the discussions. A cluster of deeper personal changes thematically described as Self-Identity, Autonomy, and Positive Character Development accounted for another 16.5% of the responses. Relatively few commentaries emphasized negative effects (7.1%. Converting the proportions of qualitative data into a quantitative index allowed us to analyze potential differences in emphasis according to sex, age, and school type. Though a few significant findings emerged, the larger pattern was of a uniform perceptual map across the variables for this adolescent sample. Implications drawn from this investigation highlight the need to clearly articulate concrete pathways to positive nonphysical changes (e.g., mood states, autonomy, positive character development from engagements in sports and PA.

  11. The interplay between dynamic heterogeneities and structure of bulk liquid water: A molecular dynamics simulation study.

    Science.gov (United States)

    Demontis, Pierfranco; Gulín-González, Jorge; Masia, Marco; Sant, Marco; Suffritti, Giuseppe B

    2015-06-28

    In order to study the interplay between dynamical heterogeneities and structural properties of bulk liquid water in the temperature range 130-350 K, thus including the supercooled regime, we use the explicit trend of the distribution functions of some molecular properties, namely, the rotational relaxation constants, the atomic mean-square displacements, the relaxation of the cross correlation functions between the linear and squared displacements of H and O atoms of each molecule, the tetrahedral order parameter q and, finally, the number of nearest neighbors (NNs) and of hydrogen bonds (HBs) per molecule. Two different potentials are considered: TIP4P-Ew and a model developed in this laboratory for the study of nanoconfined water. The results are similar for the dynamical properties, but are markedly different for the structural characteristics. In particular, for temperatures higher than that of the dynamic crossover between "fragile" (at higher temperatures) and "strong" (at lower temperatures) liquid behaviors detected around 207 K, the rotational relaxation of supercooled water appears to be remarkably homogeneous. However, the structural parameters (number of NNs and of HBs, as well as q) do not show homogeneous distributions, and these distributions are different for the two water models. Another dynamic crossover between "fragile" (at lower temperatures) and "strong" (at higher temperatures) liquid behaviors, corresponding to the one found experimentally at T(∗) ∼ 315 ± 5 K, was spotted at T(∗) ∼ 283 K and T(∗) ∼ 276 K for the TIP4P-Ew and the model developed in this laboratory, respectively. It was detected from the trend of Arrhenius plots of dynamic quantities and from the onset of a further heterogeneity in the rotational relaxation. To our best knowledge, it is the first time that this dynamical crossover is detected in computer simulations of bulk water. On the basis of the simulation results, the possible mechanisms of the two

  12. A numerical model for water and heat transport in freezing soils with nonequilibrium ice-water interfaces

    Science.gov (United States)

    Peng, Zhenyang; Tian, Fuqiang; Wu, Jingwei; Huang, Jiesheng; Hu, Hongchang; Darnault, Christophe J. G.

    2016-09-01

    A one-dimensional numerical model of heat and water transport in freezing soils is developed by assuming that ice-water interfaces are not necessarily in equilibrium. The Clapeyron equation, which is derived from a static ice-water interface using the thermal equilibrium theory, cannot be readily applied to a dynamic system, such as freezing soils. Therefore, we handled the redistribution of liquid water with the Richard's equation. In this application, the sink term is replaced by the freezing rate of pore water, which is proportional to the extent of supercooling and available water content for freezing by a coefficient, β. Three short-term laboratory column simulations show reasonable agreement with observations, with standard error of simulation on water content ranging between 0.007 and 0.011 cm3 cm-3, showing improved accuracy over other models that assume equilibrium ice-water interfaces. Simulation results suggest that when the freezing front is fixed at a specific depth, deviation of the ice-water interface from equilibrium, at this location, will increase with time. However, this deviation tends to weaken when the freezing front slowly penetrates to a greater depth, accompanied with thinner soils of significant deviation. The coefficient, β, plays an important role in the simulation of heat and water transport. A smaller β results in a larger deviation in the ice-water interface from equilibrium, and backward estimation of the freezing front. It also leads to an underestimation of water content in soils that were previously frozen by a rapid freezing rate, and an overestimation of water content in the rest of the soils.

  13. Study of a criticality accident involving fuel rods and water outside a power reactor; Etude d'un accident de criticite mettant en presence des crayons combustibles et de l'eau hors reacteur de puissance

    Energy Technology Data Exchange (ETDEWEB)

    Beloeil, L

    2000-05-30

    It is possible to imagine highly unlikely but numerous accidental situations where fuel rods come into contact with water under conditions close to atmospheric values. This work is devoted to modelling and simulation of first instants of the power excursion that may result from such configurations. We show that void effect is a preponderant feedback for most severe accidents. The formation of a vapour film around the rods is put forward and confirmed with the help of experimental transients using electrical heating. We propose then a vapour/liquid flow model able to reproduce void fraction evolution. The vapour film is treated as a compressible medium. Conservation balance equations are solved on a moving mesh with a two-dimensional scheme and boundary conditions taking notice of interfacial phenomena and axial escape possibility. Movements of the liquid phase are modelled through a non-stationary integral equation and a dissipative term suited to the particular geometry of this flow. The penetration of energy into the liquid is also calculated. Thus, the coupling of aerodynamic and hydrodynamic modules gives results in excellent agreement with experiments. Next, neutronic phenomena into the fuel pellet, their feedback effects and the distribution of power through the rod are numerically translated. For each developed module, validation tests are provided. Then, it is possible to simulate the first seconds of the whole criticality accident. Even if this calculation tool is only a way of study as a first approach, performed simulations are proving coherent with reported data on recorded accidents. (author)

  14. Intervention or Involvement

    DEFF Research Database (Denmark)

    Liebst, Lasse Suonperä; Ejbye-Ernst, Peter; Heinskou, Marie Bruvik

    patrons plays in bouncers’ use of violence. To address this gap, we offer a micro-interactional analysis of violent behavior of bouncers. We observed video surveillance footage of naturally occurring barroom conflicts involving bouncers. A quantitative analysis shows that violence is relatively uncommon......, and when it occurs, it is associated with interactions where bouncers are a party to the conflict, compared to situations where they intervene as a third party. Further, a visual analysis of emotional cues identifies anger as a plausible mechanism leading bouncers to practice violent aggression. Thus......, adding to the situational and cultural interpretations in the literature, this study highlights interactional structures as a feature influencing the likelihood of violent bouncer behavior. In considering the implications of our study, we discuss strengths and weaknesses of applying video data analysis...

  15. Between Involvement and Detachment

    DEFF Research Database (Denmark)

    Thomasen, Gry

    a traditional reading of de Gaulle’s policies, and feared that if Gaullist thinking spread among the European allies, it would merit to a return to traditional European power politics. The analysis shows that, by 1964 the administration believed, according to this study, that NATO’s principle of integration......Between Involvement and Detachment takes grasp with the Johnson administration’s (1963-1969) perceptions of and responses to the Western European realignments. Arguing that the Johnson administration set out to maintain the American unilateralist position in the transatlantic relation, not just......, essentially, were detached as America rejected the European reason of state. The Western European realignments were recorded in the Johnson administration with de Gaulle’s critique of US hegemony in Western Europe in the early 1960s. The thesis argues that the administration to a large extent had...

  16. Fluctuating confinement of water in aqueous organic nanodroplets

    Science.gov (United States)

    Wilemski, Gerald; Hrahsheh, Fawaz

    2013-03-01

    Supercooled and nano-confined water occurs frequently as nanometer-sized aqueous-organic aerosol droplets that are ubiquitous in the atmosphere and in many industrial processes. Nanodroplet structure is important because it influences droplet growth and evaporation rates, heterogeneous reaction rates, and radiative properties. We use classical molecular dynamic simulations to study the structure of ternary water-butanol-nonane nanodroplets for several temperatures and droplet sizes. We study the effects of butanol on the wetting of the water/butanol core-shell droplet by the nonane lens. At low concentrations, butanol acts as a surfactant to significantly enhance the wetability of the water droplet by nonane. At 250 K, with sufficient butanol and nonane, perfect wetting (thin film formation by nonane) occurs. Perfect wetting also occurs at higher temperatures, 270 K to 300 K, but this wetting state is progressively destabilized at higher temperature. All of the nanodroplets studied undergo distinct transitions between partial dewetting and perfect wetting states due to isothermal fluctuations in the local distribution of butanol on the surface of the water core. These fluctuations favor the wetted state at lower temperatures and the dewetted state at higher temperatures. Supported by NSF Grant CBET 1033387

  17. Widom line and the liquid-liquid critical point for the TIP4P/2005 water model.

    Science.gov (United States)

    Abascal, José L F; Vega, Carlos

    2010-12-21

    The Widom line and the liquid-liquid critical point of water in the deeply supercooled region are investigated via computer simulation of the TIP4P/2005 model. The Widom line has been calculated as the locus of compressibility maxima. It is quite close to the experimental homogeneous nucleation line and, in the region studied, it is almost parallel to the curve of temperatures of maximum density at fixed pressure. The critical temperature is determined by examining which isotherm has a region with flat slope. An interpolation in the Widom line gives the rest of the critical parameters. The computed critical parameters are T(c)=193 K, p(c)=1350 bar, and ρ(c)=1.012 g/cm(3). Given the performance of the model for the anomalous properties of water and for the properties of ice phases, the calculated critical parameters are probably close to those of real water.

  18. [Nail involvement in leprosy].

    Science.gov (United States)

    Belinchón Romero, I; Ramos Rincón, J M; Reyes Rabell, F

    2012-05-01

    Leprosy, a disease caused by Mycobacterium leprae, primarily affects the skin and nerves, but the nails are also involved in as many as 3 out of 4 patients .The factors that trigger nail changes in leprosy are numerous and include repeated trauma, neuropathy, vascular impairment, infections, lepra reactions, and the drugs used to manage the disease. The changes most often reported include subungual hematomas, onycholysis, onychauxis, onychogryphosis, pterygium unguis, and onychoheterotopia, most of which can be attributed to nerve damage and trauma. Furthermore, the acro-osteolysis that occurs in the advanced stages of the disease may present with brachyonychia, racquet nails, or even anonychia. Infections of the nail bed leading to paronychia and onychomycosis should also be taken into account in leprosy. Other typical changes include longitudinal striae, pitting, macrolunula, Terry nails, leukonychia, hapalonychia, and Beau lines. In this review, we describe the principal nail changes associated with leprosy. These changes, which are highly varied and diverse in origin, are in fact a reflection of the significant morbidity caused by M. leprae infection.

  19. Multidrug toxicity involving sumatriptan.

    Science.gov (United States)

    Knittel, Jessica L; Vorce, Shawn P; Levine, Barry; Hughes, Rhome L; Bosy, Thomas Z

    2015-01-01

    A multidrug fatality involving sumatriptan is reported. Sumatriptan is a tryptamine derivative that acts at 5-HT(1B/1D) receptors and is used for the treatment of migraines. The decedent was a 21-year-old white female found dead in bed by her spouse. No signs of physical trauma were observed and a large number of prescription medications were discovered at the scene. Toxicological analysis of the central blood revealed sumatriptan at a concentration of 1.03 mg/L. Following therapeutic dosing guidelines, sumatriptan concentrations do not exceed 0.095 mg/L. Sumatriptan was isolated by solid-phase extraction and analyzed using liquid chromatography-tandem mass spectrometry in multiple reaction monitoring mode. A tissue distribution study was completed with the following concentrations measured: 0.61 mg/L in femoral blood, 0.56 mg/L in iliac blood, 5.01 mg/L in urine, 0.51 mg/kg in liver, 3.66 mg/kg in kidney, 0.09 mg/kg in heart, 0.32 mg/kg in spleen, 0.01 mg/kg in brain, 15.99 mg/kg in lung and 78.54 mg/45 mL in the stomach contents. Carisoprodol, meprobamate, fluoxetine, doxylamine, orphenadrine, dextromethorphan and hydroxyzine were also present in the blood at the following concentrations: 3.35, 2.36, 0.63, 0.19, 0.06, 0.55 and 0.16 mg/L. The medical examiner ruled the cause of death as acute mixed drug toxicity and the manner of death as accident.

  20. When water molecules meet air

    OpenAIRE

    Hsie, Cho-Shuen; Campen, R. Kramer; Verde, Ana Vila; Bolhuis, Peter; Nienhuys, Han-Kwang; Bonn, Mischa

    2012-01-01

    About 70% of our planet is covered in water. Most of that water exists as water in the bulk – the neighbors of water molecules are other water molecules – and only a small fraction of molecules are at the air-water interface. Despite the small relative abundance of interfacial water, it is of the utmost importance: it governs the chemistry involving the surface of oceans and seawater aerosols, or the small water droplets forming clouds. Reactions at the air-water interface are directly releva...

  1. Anomalous composition-dependent dynamics of nanoconfined water in the interlayer of disordered calcium-silicates.

    Science.gov (United States)

    Qomi, Mohammad Javad Abdolhosseini; Bauchy, Mathieu; Ulm, Franz-Josef; Pellenq, Roland J-M

    2014-02-07

    With shear interest in nanoporous materials, the ultraconfining interlayer spacing of calcium-silicate-hydrate (C-S-H) provides an excellent medium to study reactivity, structure, and dynamic properties of water. In this paper, we present how substrate composition affects chemo-physical properties of water in ultraconfined hydrophilic media. This is achieved by performing molecular dynamics simulation on a set of 150 realistic models with different compositions of calcium and silicon contents. It is demonstrated that the substrate chemistry directly affects the structural properties of water molecules. The motion of confined water shows a multi-stage dynamics which is characteristic of supercooled liquids and glassy phases. Inhomogeneity in that dynamics is used to differentiate between mobile and immobile water molecules. Furthermore, it is shown that the mobility of water molecules is composition-dependent. Similar to the pressure-driven self-diffusivity anomaly observed in bulk water, we report the first study on composition-driven diffusion anomaly, the self diffusivity increases with increasing confined water density in C-S-H. Such anomalous behavior is explained by the decrease in the typical activation energy required for a water molecule to escape its dynamical cage.

  2. When a water drop freezes before it solidifies

    Science.gov (United States)

    Kavehpour, Pirouz; Davis, Stephen; Tavakoli, Faryar

    2012-11-01

    When a drop of liquid is placed on a substrate which temperature is below the melting point of the liquid, one would expect the drop to solidify instantaneously. However, many liquids, such as water, must be subcooled to solidify below its melting temperature due to homogeneous nucleation's high activation energy. Most of the drop solidification research, particularly for water, phase change is assumed to occur at equilibrium freezing temperature; however, this is not the case. We found that after a certain degree of supercooling, a kinetic based nucleation begins and latent heat of fusion is suddenly liberated, causing an increase in liquid temperature. At the end of this stage, approximately 20% of the drop is crystallized. This phenomenon is known among metallurgists as recalescence. This is followed by a slow solidification process at the melting point. As a water droplet spreads on a cold substrate, its contact line stops just prior to freezing inception from the liquid-solid interface. In this study, we assert that recalescence prior to solidification may be the cause of water's sudden immobility, which results in a fixed contact angle and droplet diameter. In our experiments, the nucleation front initiates from the trijunction point and propagates to the drop volume.

  3. Health and Water

    CSIR Research Space (South Africa)

    Genthe, Bettina

    2006-01-01

    Full Text Available , bacteria, parasites and toxins, and it is a symptom of many of the illness caused by the various pathogens that might be involved in water-related disease. Non-specific diarrhoeal disease is more frequent and causes more deaths globally than cholera...-borne, water-washed, water-vectored or water-based diseases. Among the most typical water-related disease are gastroenteritis, amoebiasis, salmonellosis, dysentery, cholera, typhoid fever and hepatitis. Although there has been a general decline...

  4. Water Quality Monitoring Manual.

    Science.gov (United States)

    Mason, Fred J.; Houdart, Joseph F.

    This manual is designed for students involved in environmental education programs dealing with water pollution problems. By establishing a network of Environmental Monitoring Stations within the educational system, four steps toward the prevention, control, and abatement of water pollution are proposed. (1) Train students to recognize, monitor,…

  5. Water Pollution, Teachers' Edition.

    Science.gov (United States)

    Lavaroni, Charles W.; And Others

    One of three in a series about pollution, this teacher's guide for a unit on water pollution is designed for use in junior high school grades. It offers suggestions for extending the information and activities contained in the textual material for students. Chapter 1 discusses the problem of water pollution and involves students in processes of…

  6. Water Pollution, Teachers' Edition.

    Science.gov (United States)

    Lavaroni, Charles W.; And Others

    One of three in a series about pollution, this teacher's guide for a unit on water pollution is designed for use in junior high school grades. It offers suggestions for extending the information and activities contained in the textual material for students. Chapter 1 discusses the problem of water pollution and involves students in processes of…

  7. Cloud liquid water path and radiative feedbacks over the Southern Ocean

    Science.gov (United States)

    Bodas-Salcedo, A.; Andrews, T.; Karmalkar, A. V.; Ringer, M. A.

    2016-10-01

    Climate models show a robust shortwave negative feedback in the midlatitude oceans in climate change simulations. This feedback is commonly attributed to an increase in cloud optical depth due to ice to liquid phase change as the climate warms. Here we use a cyclone compositing technique to show that the models' cloud liquid water path (LWP) response is strongly dependent on cloud regime. The radiative and LWP responses are not as tightly coupled as a zonal-mean analysis would suggest, implying that the physical mechanisms that control the overall LWP response are not necessarily responsible for the radiative response. The area of the cyclone dominated by low-level stratiform and shallow convective clouds plays a dominant role in the radiative response. Since these are mostly supercooled liquid clouds, the strength of a negative cloud phase feedback in the real world should be smaller than the one predicted by current models.

  8. Analysis of Ice Water Path Retrieval Errors Over Tropical Ocean

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Retrieval of multi-layered cloud properties, especially ice water path (IWP), is one of the most perplexing problems in satellite cloud remote sensing. This paper develops a method for improving the IWP retrievals for ice-over-water overlapped cloud systems using Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Visible and Infrared Scanner (VIRS) data. A combined microwave, visible and infrared algorithm is used to identify overlapped clouds and estimate IWP separately from liquid water path. The retrieval error of IWP is then evaluated by comparing the IWP to that retrieved from single-layer ice clouds surrounding the observed overlapping systems. The major IWP retrieval errors of overlapped clouds are primarily controlled by the errors in estimating the visible optical depth. Optical depths are overestimated by about 10-40% due to the influence of the underlying cloud. For the ice-over-warm-water cloud systems (cloud water temperature Tw > 273 K), the globally averaged IWP retrieval error is about 10%. This cloud type accounts for about 15% of all high-cloud overlapping cases. Ice-over-super-cooled water clouds are the predominant overlapped cloud system, accounting for 55% of the cases. Their global averaged error is ~17.2%. The largest IWP retrieval error results when ice clouds occur over extremely super-cooled water clouds (Tw ≤ 255 K). Overall, roughly 33% of the VIRS IWP retrievals are overestimated due to the effects of the liquid water clouds beneath the cirrus clouds. To improve the accuracy of the IWP retrievals,correction models are developed and applied to all three types of overlapped clouds. The preliminary results indicate that the correction models reduce part of the retrieval error.

  9. Water Contamination

    Science.gov (United States)

    ... Statistics Training & Education Policy & Recommendations Fast Facts Healthy Water Sites Healthy Water Drinking Water Healthy Swimming Global ... type=”submit” value=”Submit” /> Healthy Water Home Water Contamination Recommend on Facebook Tweet Share Compartir On ...

  10. Drinking Water

    Science.gov (United States)

    ... the safest water supplies in the world, but drinking water quality can vary from place to place. It ... water supplier must give you annual reports on drinking water. The reports include where your water came from ...

  11. Automated Water-Purification System

    Science.gov (United States)

    Ahlstrom, Harlow G.; Hames, Peter S.; Menninger, Fredrick J.

    1988-01-01

    Reverse-osmosis system operates and maintains itself with minimal human attention, using programmable controller. In purifier, membranes surround hollow cores through which clean product water flows out of reverse-osmosis unit. No chemical reactions or phase changes involved. Reject water, in which dissolved solids concentrated, emerges from outer membrane material on same side water entered. Flow controls maintain ratio of 50 percent product water and 50 percent reject water. Membranes expected to last from 3 to 15 years.

  12. The freezing and thawing of water in poultry meat and vegetables irradiated by electrons at doses of 0.1-4 kGy.

    Science.gov (United States)

    Dubini, B; Ferrante, L; Leonardi, M; Messina, G; Montecchia, F; Ponzi-Bossi, M G

    1993-06-01

    Poultry meat and some vegetables, irradiated by 5 MeV electrons (0.1-4 kGy), were analysed by differential scanning calorimetry, from 24 h after irradiation. The temperature and enthalpy transitions of the water contained in the irradiated samples were measured and compared with those of unirradiated samples. We analysed 18 meat and 10 vegetable samples for each irradiation dose together with a similar number of unirradiated controls. The mean supercooling temperatures of water in the irradiated poultry meat samples and in some vegetables are significantly lower than those of controls. Moreover, the freezing enthalpies of the irradiated poultry breast are significantly lower than those of controls, while they are unchanged in the other cases. The mean ice melting temperatures and enthalpies are similar for all samples. The amount of the lowering of the water-ice transition depends on the nature of the sample and is highest in poultry breast and lowest in vegetables.

  13. Sacroiliac joint involvement in psoriasis.

    Science.gov (United States)

    Kaçar, Cahit; Sezer, Ilhan; Kocabaş, Hilal; Cay, Hasan Fatih; Cevikol, Can; Alpsoy, Erkan; Melikoğlu, Meltem Alkan; Akman, Ayşe

    2010-07-01

    Psoriasis is a skin disorder that is associated with arthritis. Sacroiliac joint involvement is considered to be less frequent than the other types of psoriatic arthritis. Additionally, the psoriatic sacroiliitis is considered to be asymmetric in general. We aimed to define the frequency and type of sacroiliac involvement in patients with psoriasis. Patients with psoriasis were included the study. Characteristics of skin, nail and articular involvement were noted. Psoriasis area and severity index was calculated. Antero-posterior pelvic X-rays were obtained and graded by two rheumatologists and a radiologist independently. One hundred and thirty-three patients were included. Thirty-seven of patients (27%) have articular involvement symptomatically. The sacroiliac joint involvement was observed in 34 (26%) of patients. More than one-half of sacroiliac involvement was bilateral while less than one-half was in symptomatic patients regarding sacroiliitis. Fifty-seven percentages of all patients have psoriatic nail involvement. Sacroiliac joint involvement did not show any significant association with psoriatic nail involvement or the severity of skin disease. We found higher frequency of sacroiliac joint involvement and bilateral sacroiliitis in patients with psoriasis. This is in contrast to present information about the association of psoriasis and sacroiliitis. These findings need confirmation by further studies and with more sophisticated techniques such as magnetic resonance imaging.

  14. The structure and terahertz dynamics of water confined in nanoscale pools in salt solutions.

    Science.gov (United States)

    Turton, David A; Corsaro, Carmelo; Candelaresi, Marco; Brownlie, Angela; Seddon, Ken R; Mallamace, Francesco; Wynne, Klaas

    2011-01-01

    The behaviour of liquid water below its melting point is of great interest as it may hold clues to the properties of normal liquid water and of water in and on the surfaces of biomolecules. A second critical point, giving rise to a polyamorphic transition between high and low density water, may be hidden in the supercooled region but cannot be observed directly. Here it is shown that water can be locked up in nano-pools or worm-like structures using aqueous LiCl salt solutions and can be studied with terahertz spectroscopies. Very high dynamic range ultrafast femtosecond optical Kerr effect (OKE) spectroscopy is used to study the temperature-dependent behaviour of water in these nano-pools on timescales from 10 fs to 4 ns. These experiments are complemented by temperature-dependent nuclear magnetic resonance (NMR) diffusion measurements, concentration-dependent Fourier-transform infrared (FTIR) measurements, and temperature-dependent rheology. It is found that liquid water in the nanoscale pools undergoes a fragile-to-strong transition at about 220 K associated with a sharp increase in the inhomogeneity of translational dynamics.

  15. M3B: A coarse grain model for the simulation of oligosaccharides and their water mixtures.

    Science.gov (United States)

    Goddard, William A.; Cagin, Tahir; Molinero, Valeria

    2003-03-01

    Water and sugar dynamics in concentrated carbohydrate solutions is of utmost importance in food and pharmaceutical technology. Water diffusion in concentrated sugar mixtures can be slowed down many orders of magnitude with respect to bulk water [1], making extremely expensive the simulation of these systems with atomistic detail for the required time-scales. We present a coarse grain model (M3B) for malto-oligosaccharides and their water mixtures. M3B speeds up molecular dynamics simulations about 500-1000 times with respect to the atomistic model while retaining enough detail to be mapped back to the atomistic structures with low uncertainty in the positions. The former characteristic allows the study of water and carbohydrate dynamics in supercooled and polydisperse mixtures with characteristic time scales above the nanosecond. The latter makes M3B well suited for combined atomistic-mesoscale simulations. We present the parameterization of M3B force field for water and a family of technologically relevant glucose oligosaccharides, the alpha-(1->4) glucans. The coarse grain force field is completely parameterized from atomistic simulations to reproduce the density, cohesive energy and structural parameters of amorphous sugars. We will show that M3B is capable to describe the helical character of the higher oligosaccharides, and that the water structure in low moisture mixtures shows the same features obtained with the atomistic and M3B models. [1] R Parker, SG Ring: Carbohydr. Res. 273 (1995) 147-55.

  16. INVOLVEMENT

    Directory of Open Access Journals (Sweden)

    Yeşim ULUSU

    2016-01-01

    Full Text Available The concept of “Involvement” is based on social psychology and specially attitude and attitude change subjects in the area of persuasive communication. The conceptualization of the “involvement” as a phe- nomenon was started to construct especially during the years between 1965-1980 when “involvement” was discussed in many areas of social sciences related to human behavior such as marketing, consumer behavior and advertising with its different dimensions.

  17. INVOLVEMENT

    OpenAIRE

    ULUSU, Yeşim

    2016-01-01

    The concept of “Involvement” is based on social psychology and specially attitude and attitude change subjects in the area of persuasive communication. The conceptualization of the “involvement” as a phe- nomenon was started to construct especially during the years between 1965-1980 when “involvement” was discussed in many areas of social sciences related to human behavior such as marketing, consumer behavior and advertising with its different dimensions.

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

    Science.gov (United States)

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

    2005-01-01

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

  19. Monoarticular Hip Involvement in Pseudogout

    Directory of Open Access Journals (Sweden)

    Figen Kocyigit

    2015-01-01

    Full Text Available Pseudogout is the acutest form of arthritis in the elderly. Although clinical manifestations vary widely, polyarticular involvement is typical mimicking osteoarthritis or rheumatoid arthritis. Monoarticular involvement is relatively rare and is generally provoked by another medical condition. There are reported cases of hip involvement by pseudogout in monoarticular form. However, all of the cases were presented as septic arthritis. In this report, we present a case of monoarticular hip involvement mimicking soft tissue abscess. We confirmed the pseudogout diagnosis after ultrasonographic evaluation of the involved hip joint and pathological and biochemical analysis of synovial fluid analysis. Diagnosis is important to avoid unnecessary medical and surgical treatment in cases of the bizarre involvement of hip in pseudogout.

  20. Skin involvement in Dupuytren's disease.

    OpenAIRE

    Wade, R.; Igali, L; Figus, A

    2016-01-01

    Whether the palmar skin has a role in the development, propagation or recurrence of Dupuytren's disease remains unclear. Clinical assessment for skin involvement is difficult and its correlation with histology uncertain. We prospectively biopsied the palmar skin of consecutive patients undergoing single digit fasciectomy (for primary Dupuytren's disease without clinically involved skin) and dermofasciectomy (for clinically involved skin or recurrence) in order to investigate this relationship...

  1. Involvement of a community in schistosomiasis control: a Kenyan experience.

    Science.gov (United States)

    Katsivo, M N; Muthami, L N; Kimani, S; Karama, M; Kingori, F

    1993-08-01

    This paper illustrates how community participation was achieved in a study that was carried out between 1983-1988 whose general objective was to reduce the transmission of schistosomiasis in a rice irrigation scheme in Kenya. A community of 2,219 people was mobilized through health education, to effect changes in behaviour regarding water contact, water use and faecal disposal. Health education, alternative water sources, latrines and mass chemotherapy with praziquantel were the schistosomiasis control strategies utilized in this study. By the end of 2 years, the canals were cleared of their thick vegetation, water, sanitation, bathing and washing facilities were constructed, water contact with infective waters was reduced, faecal contamination of water was reduced, the people's knowledge on schistosomiasis increased and the rate and intensity of schistosomiasis infection was reduced. The study demonstrated that it is possible to fully involve the community in disease control efforts.

  2. Community involvement in social marketing: guineaworm control.

    Science.gov (United States)

    Brieger, W R; Ramakrishna, J; Adeniyi, J D

    1986-01-01

    Social marketing as a health education strategy has the potential for encouraging the adoption of new health technologies. The focus on the individual, though, holds the risk of victim blaming. This can be overcome if the consumers/community are involved in the four major components of the marketing strategy-product design, price, distribution and promotion. The community of Idere, Nigeria, has recently been involved in marketing a monofilament nylon cloth filter to prevent the water-borne helminthic disease, guineaworm. Local tailors produced the filters. Volunteer primary health workers debated pricing, sold the product and educated each consumer. Coverage in those neighborhoods and farm settlements where primary health workers were resident was nearly double that of other sections showing the value of local action to market health changes.

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

    Science.gov (United States)

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

    2013-09-21

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

  4. Citizen Involvement in Public Television.

    Science.gov (United States)

    Wenner, Lawrence A.

    The purpose of this study was to evaluate the amount and quality of citizen involvement in public television. From the perspective of the "average citizen," the concept of involvement is considered with regard to the Carnegie Commission, the Corporation for Public Broadcasting (CPB) borad of directors, the National Citizens Committee for…

  5. Preparing Teachers for Parent Involvement.

    Science.gov (United States)

    Safran, Daniel

    This paper examines the potential impact of parent involvement in the formal education of their children and suggests ways that teacher education can be restructured to prepare teachers to work with parents. This paper attempts to answer five questions: (1) Why should parents be involved in the formal education of their children? (2) Why should…

  6. Parental Involvement and Academic Achievement

    Science.gov (United States)

    Goodwin, Sarah Christine

    2015-01-01

    This research study examined the correlation between student achievement and parent's perceptions of their involvement in their child's schooling. Parent participants completed the Parent Involvement Project Parent Questionnaire. Results slightly indicated parents of students with higher level of achievement perceived less demand or invitations…

  7. Involvement of inositol in reproduction.

    NARCIS (Netherlands)

    Beemster, P.; Groenen, P.; Steegers-Theunissen, R.P.M.

    2002-01-01

    Inositol is involved in several aspects of reproduction. It affects overall embryogenesis, may prevent neural tube defects, and stimulates the production of lung surfactant. This article will review the involvement of inositol in reproduction. After describing the biologic function of inositol and i

  8. Direct Employee Involvement Quality (DEIQ)

    NARCIS (Netherlands)

    Torka, Nicole; Woerkom, van Marianne; Looise, Jan-Kees

    2008-01-01

    This paper focuses on one aspect of human resource management (HRM) that is important for innovative employee behaviour: direct employee involvement quality (DEIQ). However, research has also shown that employee involvement is often in serious need of improvement. This paper presents evidence from t

  9. Parental Involvement and Academic Achievement

    Science.gov (United States)

    Goodwin, Sarah Christine

    2015-01-01

    This research study examined the correlation between student achievement and parent's perceptions of their involvement in their child's schooling. Parent participants completed the Parent Involvement Project Parent Questionnaire. Results slightly indicated parents of students with higher level of achievement perceived less demand or invitations…

  10. Water governance and institutional change

    NARCIS (Netherlands)

    Kuks, S.M.M.

    2004-01-01

    This dissertation is about water governance and institutional change. The focus on water governance means that we are interested in collective action with respect to water issues, which is not restricted to government action by public authorities, but includes involvement and participative action by

  11. Viruses in renovated waters

    CSIR Research Space (South Africa)

    Nupen, EM

    1974-06-01

    Full Text Available . SPRODI, O.J. (1973) Quality of recycled water. Fate of infectious agents. Jour. Inst. Can. Sd. Technol. Aliment 6 (2), 91. 6. SPROUL, O.J., LAROCHELLE, L.R., WENTWORTH, B.?. and PHORUP, R.T. (1967) Virus removal in water re?use treating processes... to assess the present and future needs f?r such water~ and the virus risk involved in their usage. The available knowledge of the efficiency of natural purification processes in virus removal, by water purification techniques treating possibly polluted...

  12. Production of heavy water

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, Larry S.; Brown, Sam W.; Phillips, Michael R.

    2017-06-06

    Disclosed are methods and apparatuses for producing heavy water. In one embodiment, a catalyst is treated with high purity air or a mixture of gaseous nitrogen and oxygen with gaseous deuterium all together flowing over the catalyst to produce the heavy water. In an alternate embodiment, the deuterium is combusted to form the heavy water. In an alternate embodiment, gaseous deuterium and gaseous oxygen is flowed into a fuel cell to produce the heavy water. In various embodiments, the deuterium may be produced by a thermal decomposition and distillation process that involves heating solid lithium deuteride to form liquid lithium deuteride and then extracting the gaseous deuterium from the liquid lithium deuteride.

  13. Urban water interfaces

    Science.gov (United States)

    Gessner, M. O.; Hinkelmann, R.; Nützmann, G.; Jekel, M.; Singer, G.; Lewandowski, J.; Nehls, T.; Barjenbruch, M.

    2014-06-01

    Urban water systems consist of large-scale technical systems and both natural and man-made water bodies. The technical systems are essential components of urban infrastructure for water collection, treatment, storage and distribution, as well as for wastewater and runoff collection and subsequent treatment. Urban aquatic ecosystems are typically subject to strong human influences, which impair the quality of surface and ground waters, often with far-reaching impacts on downstream aquatic ecosystems and water users. The various surface and subsurface water bodies in urban environments can be viewed as interconnected compartments that are also extensively intertwined with a range of technical compartments of the urban water system. As a result, urban water systems are characterized by fluxes of water, solutes, gases and energy between contrasting compartments of a technical, natural or hybrid nature. Referred to as urban water interfaces, boundaries between and within these compartments are often specific to urban water systems. Urban water interfaces are generally characterized by steep physical and biogeochemical gradients, which promote high reaction rates. We hypothesize that they act as key sites of processes and fluxes with notable effects on overall system behaviour. By their very nature, urban water interfaces are heterogeneous and dynamic. Therefore, they increase spatial heterogeneity in urban areas and are also expected to contribute notably to the temporal dynamics of urban water systems, which often involve non-linear interactions and feedback mechanisms. Processes at and fluxes across urban water interfaces are complex and less well understood than within well-defined, homogeneous compartments, requiring both empirical investigations and new modelling approaches at both the process and system level. We advocate an integrative conceptual framework of the urban water system that considers interfaces as a key component to improve our fundamental

  14. Lilienfeld Prize Talk: New Results on Water in Bulk, Nanoconfined, and Biological Environments

    Science.gov (United States)

    Stanley, H. Eugene

    2008-04-01

    This talk will introduce some of the 63 unsolved mysteries of water, and will demonstrate some recent progress in solving them combining information provided by water in bulk, nanoconfined, and biological environments. In particular, we will present evidence from experiments designed to test the hypothesis that water displays ``polymorphism'' in that it can exist in two liquid different phases and display a novel liquid-liquid critical point. The concept of liquid polymorphism is also proving useful in understanding some of the anomalies of other liquids with local tetrahedral symmetry, such as silicon, silica, and carbon. In particular, the talk will discuss changes in dynamic transport properties [1], and water in biological environments, including a possible physical explanation for the phenomenon known as the protein glass transition [2]. [1] P. Kumar, S. V. Buldyrev, S. L. Becker, P. H. Poole, F. W. Starr, and H. E. Stanley, ``Relation between the Widom line and the Breakdown of the Stokes--Einstein Relation in Supercooled Water,'' Proc. Natl. Acad. Sci. USA 104, 9575-9579 (2007). [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).

  15. Ocular involvement in pemphigus vulgaris.

    Science.gov (United States)

    Akhyani, Maryam; Keshtkar-Jafari, Alireza; Chams-Davatchi, Cheyda; Lajevardi, Vahide; Beigi, Sara; Aghazadeh, Nessa; Rayati Damavandi, Maede; Arami, Shabnam

    2014-07-01

    Pemphigus vulgaris (PV) is an autoimmune disorder affecting the skin and mucous membranes. Ocular involvement in PV has been reported but its prevalence and clinical characteristics are not well defined. This prospective cross-sectional study of 103 PV patients was designed to determine the prevalence, clinical types and epidemiological trends of ocular involvement in a population of Iranian patients with PV. Ocular involvement was present in 17 (16.5%) patients. Conjunctivitis was the most prevalent type of ocular involvement (9/17, 52.9%), followed by erosion of the palpebral conjunctiva (7/17, 41.2%). Erosion of the bulbar conjunctiva was noted in only one patient (5.9%). The most commonly reported symptoms were eye irritation (76.5%) and redness (76.5%). No significant relation was found between ocular involvement and disease activity (partial remission or relapse). Mucoid discharge was significantly more common in patients with conjunctival erosions as compared to patients with conjunctivitis (P = 0.038). We conclude that ocular involvement is not rare in PV; 16.5% of PV patients develop ocular disease independent of the disease activity and extension. Conjunctivitis is the most common type of involvement, however, palpebral conjunctival erosion is more frequent than previously realized.

  16. 低介入度产品迷惑式品牌名称的原产地认知研究——以瓶装水、洗发水、服装为例%Brand Origin Perception of Confusing Brand Names of Low-involved Products Taking Examples of Bottled Water, Shampoo, and Apparel

    Institute of Scientific and Technical Information of China (English)

    潘煜; 朱凌; 刘丹

    2012-01-01

    In Chinese market many firms employ confusing brand names. Are consumers really confused? This paper testifies Brand Origin Recognition Accuracy of low-involved products ( BORALOw) using the bottled water, shampoo and apparel and finds out that; consumers have limited knowledge of BORALOW; their education, income and gender directly influence BORALOW, and the education and age indirectly affect BORALOW through a mediator, consumer ethnocentric tendencies. The study suggests that Chinese consumers do not know brand origin of low-involved products, questions the concealed pre-assumption of researches on country of origin, advises to Chinese researches on country of origin, and establishes a model about consumers' perception of BORALOw.%以瓶装水、洗发水、服装为研究对象测量中国消费者对低介入度产品的品牌原产地识别准确度( BORA低),发现消费者的BORA低比较低;教育、经济收入、性别直接影响BORA低,并且教育、年龄通过民族中心主义观念这个中介变量间接影响BORA低.研究揭示中国消费者不清楚低介入度产品的原产地信息,说明原产地研究的隐含假设值得商榷,对国内原产地研究提出建议,并且建立消费者对于BORA低的认知模型.

  17. Road rage and collision involvement.

    Science.gov (United States)

    Mann, Robert E; Zhao, Jinhui; Stoduto, Gina; Adlaf, Edward M; Smart, Reginald G; Donovan, John E

    2007-01-01

    To assess the contribution of road rage victimization and perpetration to collision involvement. The relationship between self-reported collision involvement and road rage victimization and perpetration was examined, based on telephone interviews with a representative sample of 4897 Ontario adult drivers interviewed between 2002 and 2004. Perpetrators and victims of both any road rage and serious road rage had a significantly higher risk of collision involvement than did those without road rage experience. This study provides epidemiological evidence that both victims and perpetrators of road rage experience increased collision risk. More detailed studies of the contribution of road rage to traffic crashes are needed.

  18. GOVERNMENT INVOLVEMENT IN CONSUMPTION BEHAVIOUR

    Directory of Open Access Journals (Sweden)

    CRISTINA ZAMFIR

    2010-01-01

    Full Text Available In this article, we will follow the involvement that the government has,through its expenses, on the consumption behavior. The involvement that the government has inthe consumption behavior is made through fees and taxes that are applied on income. Fees andtaxes are applied to the different forms of income but in this article we will be focused only onthe influence of them on wages. In order to analyze the involvement of government expenses onconsumption behavior an utility model will be used.

  19. The potential influence of Asian and African mineral dust on ice, mixed-phase and liquid water clouds

    Directory of Open Access Journals (Sweden)

    A. Wiacek

    2010-09-01

    Full Text Available This modelling study explores the availability of mineral dust particles as ice nuclei for interactions with ice, mixed-phase and liquid water clouds, also tracking the particles' history of cloud-processing. We performed 61 320 one-week forward trajectory calculations originating near the surface of major dust emitting regions in Africa and Asia using high-resolution meteorological analysis fields for the year 2007. Dust-bearing trajectories were assumed to be those coinciding with known dust emission seasons, without explicitly modelling dust emission and deposition processes. We found that dust emissions from Asian deserts lead to a higher potential for interactions with high ice clouds, despite being the climatologically much smaller dust emission source. This is due to Asian regions experiencing significantly more ascent than African regions, with strongest ascent in the Asian Taklimakan desert at ~25%, ~40% and 10% of trajectories ascending to 300 hPa in spring, summer and fall, respectively. The specific humidity at each trajectory's starting point was transported in a Lagrangian manner and relative humidities with respect to water and ice were calculated in 6-h steps downstream, allowing us to estimate the formation of liquid, mixed-phase and ice clouds. Downstream of the investigated dust sources, practically none of the simulated air parcels reached conditions of homogeneous ice nucleation (T≲−40 °C along trajectories that have not experienced water saturation first. By far the largest fraction of cloud forming trajectories entered conditions of mixed-phase clouds, where mineral dust will potentially exert the biggest influence. The majority of trajectories also passed through atmospheric regions supersaturated with respect to ice but subsaturated with respect to water, where so-called "warm ice clouds" (T≳−40 °C theoretically may form prior to supercooled water or mixed-phase clouds. The importance of "warm ice

  20. [Hand involvement in systemic sclerosis].

    Science.gov (United States)

    Mouthon, Luc

    2013-12-01

    Hand involvement is very common in patients with systemic sclerosis and represents an important tool for the early diagnosis of the disease. Vascular involvement of the hands is at the forefront of systemic sclerosis, with Raynaud's phenomenon, which may be complicated by digital ulcers, digital necrosis causing pain, infection and significant disability. Joint inflammation can also be disabling and causes the occurrence of contractures and deformities resulting in a marked hand disability. Skin sclerosis involving fingers and hands leads to the occurrence of pain and functional impairment. Hand involvement contributes to 75 % of global disability in patients with systemic sclerosis. Only a comprehensive care, taking into account the vascular, skin and joint manifestations, including physical therapy if needed can improve hand function in patients with systemic sclerosis.

  1. Abdominal Actinomycetoma With Lymphnode Involvement

    Directory of Open Access Journals (Sweden)

    Damisetty Rajetha

    2004-01-01

    Full Text Available Actinomycotic mycetoma of the anterior abdominal wall with inguinal lymphnode involvement, an exceedingly rare entity is described here with mycological histological features. Remarkable therapeutic response was noted with Welsh regimen.

  2. User Involvement And Entrepreneurial Action

    Directory of Open Access Journals (Sweden)

    Eva Heiskanen

    2007-01-01

    Full Text Available Involving users in the innovation process is a subject of much research, experimentation, and debate. Less attention has been given to the limits to user involvement that ensue from specific organizational characteristics. This article explores barriers to the utilization of users’ input in two small companies developing interactive digital applications. We contrast our findings to earlier research involving large companies to identify features of entrepreneurial sensemaking and action that influence the utilization of users’ input. We find that the small companies follow a distinct action rationality, leading to rapid implementation of some user inputs, and defensiveness toward others. Both sets of data also reveal common features that are often overlooked in the literature. We reconceptualize user involvement as a form of interaction between users and innovating companies that is facilitated and constrained by micro-sociological processes, on the one hand, and the nature of the competitive environment, on the other.

  3. Patient involvement in hospital architecture

    DEFF Research Database (Denmark)

    Herriott, Richard

    2017-01-01

    This paper examines user-involvement in the process used to design new hospitals. Denmark is in the midst of a phase of hospital building. This recent experience is studied by means of expert interviews with senior practitioners involved in three projects. Examined thematically, the data covers......-studied area, design for hospitals. It highlights difficulties in applying the goals of user-centred design and Design for All in large projects....

  4. Temperature dependence of the microscopic structure and density anomaly of the SPC/E and TIP4P-Ew water models. Molecular dynamics simulation results

    Directory of Open Access Journals (Sweden)

    E. Galicia-Andrés

    2015-03-01

    Full Text Available We have investigated temperature trends of the microscopic structure of the SPC/E and TIP4P-Ew water models in terms of the pair distribution functions, coordination numbers, the average number of hydrogen bonds, the distribution of bonding states of a single molecule as well as the angular distribution of molecules by using the constant pressure molecular dynamics simulations. The evolution of the structure is put in correspondence with the dependence of water density on high temperatures down to the region of temperatures where the system becomes supercooled. It is shown that the fraction of molecules with three and four bonds determine the maximum density for both models. Moreover, the temperature dependence of the dielectric constant is obtained and analyzed.

  5. Experimental Study on Hydrate Induction Time of Gas-Saturated Water-in-Oil Emulsion using a High-Pressure Flow Loop

    Directory of Open Access Journals (Sweden)

    Lv X.F.

    2015-11-01

    Full Text Available Hydrate is one of the critical precipitates which have to be controlled for subsea flow assurance. The induction time of hydrate is therefore a significant parameter. However, there have been few studies on the induction time of the natural gas hydrate formation in a flow loop system. Consequently, a series of experiments were firstly performed, including water, natural gas and Diesel oil, on the hydrate induction time under various conditions such as the supercooling and supersaturation degree, water cut, anti-agglomerant dosage, etc. The experiments were conducted in a high-pressure hydrate flow loop newly constructed in the China University of Petroleum (Beijing, and dedicated to flow assurance studies. Then, based on previous research, this study puts forward a method for induction time, which is characterized by clear definition, convenient measurement and good generality. Furthermore, we investigated the influences of the experimental parameters and analyzed the experimental phenomena for the hydrate induction time in a flowing system.

  6. Water resources data, Kentucky. Water year 1991

    Energy Technology Data Exchange (ETDEWEB)

    McClain, D.L.; Byrd, F.D.; Brown, A.C.

    1991-12-31

    Water resources data for the 1991 water year for Kentucky consist of records of stage, discharge, and water quality of streams and lakes; and water-levels of wells. This report includes daily discharge records for 115 stream-gaging stations. It also includes water-quality data for 38 stations sampled at regular intervals. Also published are 13 daily temperature and 8 specific conductance records, and 85 miscellaneous temperature and specific conductance determinations for the gaging stations. Suspended-sediment data for 12 stations (of which 5 are daily) are also published. Ground-water levels are published for 23 recording and 117 partial sites. Precipitation data at a regular interval is published for 1 site. Additional water data were collected at various sites not involved in the systematic data-collection program and are published as miscellaneous measurement and analyses. These data represent that part of the National Water Data System operated by the US Geological Survey and cooperation State and Federal agencies in Kentucky.

  7. Water Saving for Development

    Science.gov (United States)

    Zacharias, Ierotheos

    2013-04-01

    The project "Water Saving for Development (WaS4D)" is financed by European Territorial Cooperational Programme, Greece-Italy 2007-2013, and aims at developing issues on water saving related to improvement of individual behaviors and implementing innovative actions and facilities in order to harmonize policies and start concrete actions for a sustainable water management, making also people and stakeholders awake to water as a vital resource, strategic for quality of life and territory competitiveness. Drinkable water saving culture & behavior, limited water resources, water supply optimization, water resources and demand management, water e-service & educational e-tools are the key words of WaS4D. In this frame the project objectives are: • Definition of water need for domestic and other than domestic purposes: regional and territorial hydro-balance; • promotion of locally available resources not currently being used - water recycling or reuse and rainwater harvesting; • scientific data implementation into Informative Territorial System and publication of geo-referred maps into the institutional web sites, to share information for water protection; • participated review of the regulatory framework for the promotion of water-efficient devices and practices by means of the definition of Action Plans, with defined targets up to brief (2015) and medium (2020) term; • building up water e-services, front-office for all the water issues in building agricultural, industrial and touristic sectors, to share information, procedures and instruments for the water management; • creation and publication of a user friendly software, a game, to promote sustainability for houses also addressed to young people; • creation of water info point into physical spaces called "Water House" to promote education, training, events and new advisory services to assist professionals involved in water uses and consumers; • implementation of participatory approach & networking for a

  8. Melting of the precipitated ice IV in LiCl aqueous solution and polyamorphism of water.

    Science.gov (United States)

    Mishima, Osamu

    2011-12-08

    Melting of the precipitated ice IV in supercooled LiCl-H(2)O solution was studied in the range of 0-0.6 MPa and 160-270 K. Emulsified solution was used to detect this metastable transition. Ice IV was precipitated from the aqueous solution of 2.0 mol % LiCl (or 4.8 mol % LiCl) in each emulsion particle at low-temperature and high-pressure conditions, and the emulsion was decompressed at different temperatures. The melting of ice IV was detected from the temperature change of the emulsified sample during the decompression. There was an apparently sudden change in the slope of the ice IV melting curve (liquidus) in the pressure-temperature diagram. At the high-pressure and high-temperature side of the change, the solute-induced freezing point depression was observed. At the low-pressure and low-temperature side, ice IV transformed into ice Ih on the decompression, and the transition was almost unrelated to the concentration of LiCl. These experimental results were roughly explained by the presumed existence of two kinds of liquid water (low-density liquid water and high-density liquid water), or polyamorphism in water, and by the simple assumption that LiCl dissolved maily in high-density liquid water.

  9. Effect of Colloidal Interactions on the Rate of Interdroplet Heterogeneous Nucleation in Oil-in-Water Emulsions

    Science.gov (United States)

    McClements; Dungan

    1997-02-01

    Pulsed nuclear magnetic resonance was used to monitor the crystallization of supercooled liquid droplets in 30 wt% n-hexadecane oil-in-water emulsions at 6°C. Crystallization was induced in the liquid droplets when solid droplets of the same material were present. The rate of induced crystallization increased as the concentration of free non-ionic surfactant (polyoxyethylene sorbitan monolaurate) in the aqueous phase increased from 0 to 14 wt%. Differential scanning calorimetry measurements indicated that free surfactant had no effect on crystal nucleation of individual droplets. These results indicate that the surfactant enhances induced crystallization by altering colloidal interactions between droplets. Creaming measurements showed that flocculation was enhanced in emulsions when the free surfactant concentration was increased. We propose that the presence of free surfactant micelles increases the attraction between droplets because of an osmotic effect, and this attraction facilitates the ability of solid crystals from one droplet to induce crystallization in an adjacent liquid droplet.

  10. Water Filtration Products

    Science.gov (United States)

    1986-01-01

    American Water Corporation manufactures water filtration products which incorporate technology originally developed for manned space operations. The formula involves granular activated charcoal and other ingredients, and removes substances by catalytic reactions, mechanical filtration, and absorption. Details are proprietary. A NASA literature search contributed to development of the compound. The technology is being extended to a deodorizing compound called Biofresh which traps gas and moisture inside the unit. Further applications are anticipated.

  11. User involvement in care work

    DEFF Research Database (Denmark)

    Dybbroe, Betina; Kamp, Annette

    effectiveness and shared responsibility for care pathways. While NPM position users as consumers making their free choice, the user involvement paradigm underlines the users’ active participation in the mastering of their problems and disease. Research is scarce on this theme, and has until now primarily......In recent years user involvement has become a paradigm for transforming the health and social care sector. This development–also labelled empowerment, co-creation, partnership, patient-centeredness - is seen as a means to reform organizations in ways that enhance quality, economic cost...... addressed the way this paradigm affects the users, in specific sectors. However user involvement also affects working life. It may imply change and redistribution of tasks and identities between users and professionals, and may also transform the relations of care. In this paper we explore the possible...

  12. Strategy Innovation with Employee Involvement

    DEFF Research Database (Denmark)

    Friis, Ole Uhrskov; Koch, Christian

    2015-01-01

    if the managers still dominate, some processes of direct involvement of employees occur, in particular when employees are asked to supplement overall strategic goals and when they directly shape several sub-strategies. Strategy practices found include strategy planning, an open space workshop and organised......The purpose of this article is to investigate how employees can be involved in strategy innovation processes and how new strategy practices (new tools and procedures) are used to change strategy praxis in order to sustain value creation. In the strategizing actions, we found that even...... strategy projects. Especially the latter two are important in facilitating the employee involvement. The case, however, also exhibits enterprise-situated praxises related to unplanned events, like the mitigation of taboos....

  13. Involving Employees in Strategy innovation

    DEFF Research Database (Denmark)

    Friis, Ole Uhrskov; Koch, Christian

    2011-01-01

    some of its employees. Even if managers still dominate, some processes of direct involvement of employees occur. The employees are in particular active in supplementing overall strategic goals and directly shaping one sub strategy, that of ‘process’. Strategy practices include planning, Porterian......Strategy as a practice and continuous innovation approaches are combined to conceptualise dilemmas of short versus long term and to analyse a case of employee participation as a particular example of strategy innovation. The case is a medium size textile company developing its strategy involving...... and Balanced Score Card consultancy, an ‘open space’ workshop and organized strategy projects. Especially the latter two are important in facilitating the employee involvement. The case however also exhibit enterprise situated praxis’s like mitigation of taboos....

  14. Gastrointestinal involvement in systemic sclerosis.

    Science.gov (United States)

    Savarino, Edoardo; Furnari, Manuele; de Bortoli, Nicola; Martinucci, Irene; Bodini, Giorgia; Ghio, Massimo; Savarino, Vincenzo

    2014-10-01

    Systemic sclerosis is an autoimmune chronic disease characterised by microvascular, muscular and immunologic abnormalities that lead to progressive and systemic deposition of connective tissue in the skin and internal organs. The gastrointestinal tract is often overlooked by physicians but it is the most affected organ after the skin, from the mouth to the anus. Indeed, 80% of SSc patients may present with gastrointestinal involvement. Gastrointestinal manifestations range from bloating and heartburn to dysphagia and anorectal dysfunction to severe weight loss and malabsorption. However, the gastrointestinal involvement is rarely the direct cause of death, but has great impact on quality of life and leads to several comorbidities that subsequently affect patients' survival. Treatments, including nutritional support and prokinetics provide limited benefits and do not arrest the progressive course of the disease, but earlier detection of gastrointestinal involvement may reduce the risk of complications such as malnutrition.

  15. [Heel involvement in rheumatoid polyarthritis].

    Science.gov (United States)

    Bouysset, M; Tebib, J G; Vianey, J C; Berthier, M; Nemoz, J C; Chaumentin, G; Schnepp, J; Llorca, G; Bouvier, M

    1990-11-01

    Calcaneus involvement during the course of RA is poorly known. A clinical and radiological study of 408 consecutive rheumatoid feet are then reported. If talalgia was seldomly noted (3.7 p. cent), plantar calcaneitis was found in 29.7 p. cent as plantar spur. Similarly, posterior exostosis was displayed in 30.5 p. cent of patients. These radiological abnormalities are increased in RA but appeared more as a consequence of the statical modification of the foot secondary to RA process than as a direct involvement. Logical orthopedic therapeutics are then proposed.

  16. Multisystem involvement in neuromyelitis optica

    Directory of Open Access Journals (Sweden)

    Megan M Langille

    2015-01-01

    Full Text Available We describe a case of pediatric neuromyelitis optica (NMO with muscle and lung involvement in addition to central nervous system disease. Our patient initially presented with features of area postrema syndrome, then subsequently with optic neuritis. The patient also had recurrent hyperCKemia that responded to corticosteroids. Finally, axillary and hilar adenopathy with pulmonary consolidation were noted as well and responded to immunomodulation. Our case highlights multisystem involvement in NMO including non-infectious pulmonary findings which have not been described in the pediatric population previously.

  17. Vertebral osteomyelitis without disc involvement

    Energy Technology Data Exchange (ETDEWEB)

    Kamani, I.; Syed, I.; Saifuddin, A. E-mail: asaifuddin@aol.com; Green, R.; MacSweeney, F

    2004-10-01

    Vertebral osteomyelitis is most commonly due to pyogenic or granulomatous infection and typically results in the combined involvement of the intervertebral disc and adjacent vertebral bodies. Non-infective causes include the related conditions of chronic recurrent multifocal osteomyelitis (CRMO) and SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome. Occasionally, these conditions may present purely within the vertebral body, resulting in various combinations of vertebral marrow oedema and sclerosis, destructive lesions of the vertebral body and pathological vertebral collapse, thus mimicking neoplastic disease. This review illustrates the imaging features of vertebral osteomyelitis without disc involvement, with emphasis on magnetic resonance imaging (MRI) findings.

  18. Water citizenship

    DEFF Research Database (Denmark)

    Paerregaard, Karsten; Stensrud, Astrid Bredholt; Andersen, Astrid Oberborbeck

    2016-01-01

    This article examines the implementation of Peru’s new water law and discusses how it produces new forms of water citizenship. Inspired by the global paradigm of “integrated water resources management,” the law aims to include all citizens in the management of the country’s water resources...... by embracing a “new water culture.” We ask what forms of water citizenship emerge from the new water law and how they engage with local water practices and affect existing relations of inequality. We answer these questions ethnographically by comparing previous water legislation and how the new law currently...... is negotiated and contested in three localities in Peru’s southern highlands. We argue that the law creates a new water culture that views water as a substance that is measurable, quantifiable, and taxable, but that it neglects other ways of valuing water. We conclude that water citizenship emerges from...

  19. Water, Water Everywhere, But...

    Science.gov (United States)

    Jacobson, Cliff

    Materials for teaching a unit on water pollution are provided in this teaching package. These materials include: (1) a student reading booklet; (2) a reference booklet listing a variety of popular chemical, biological, and physical tests which can be performed on a local waterway and providing information about the environmental effects and toxic…

  20. Water, Water Everywhere, But...

    Science.gov (United States)

    Jacobson, Cliff

    Materials for teaching a unit on water pollution are provided in this teaching package. These materials include: (1) a student reading booklet; (2) a reference booklet listing a variety of popular chemical, biological, and physical tests which can be performed on a local waterway and providing information about the environmental effects and toxic…