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Sample records for deeply supercooled confined

  1. Relaxation dynamics of deeply supercooled confined water in L,L-diphenylalanine micro/nanotubes.

    PubMed

    Ferreira, P M G L; Ishikawa, M S; Kogikoski, S; Alves, W A; Martinho, H

    2015-12-28

    The temperature dependence (10-290 K) of the low-frequency (20-150 cm(-1)) Raman-active phonon modes of deeply supercooled confined water in L,L-diphenylalanine micro/nanotubes was analyzed. The isolated dynamics of a specific geometry of a water cluster (pentamer) in a supercooled confined regime was studied in detail. A fragile-to-strong transition at 204 K was observed and related to the crossing of the Widom line. Analysis of peptide vibrational modes coupled to water hydrogen bonds indicated that hydrogen bond fluctuations play an irrelevant role in this system. Our results are in agreement with the second critical point of water existence hypothesis. PMID:26088917

  2. Relaxation dynamics of deeply supercooled confined water inl,l-diphenylalanine micro/nanotubes

    NASA Astrophysics Data System (ADS)

    Ferreira, P. M. G. L.; Ishikawa, M. S.; Kogikoski, S.; Alves, W. A.; Martinho, H.

    The temperature dependence (10-290 K) of the low-frequency (20-150 cm-1) Raman-active phonon modes of supercooled con?ned water in L,L-diphenylalanine micro/nanotubes was analysed. The isolated dynamics of a specific geometry of water cluster (pentamer) in supercooled confined regime was studied in detail. A particular mode concerning water-nanotube interaction was also probed. A fragile-to-strong transition at 204 K was observed and related to the crossing of the Widom line. The critical exponent analyses of the relaxation rate data based on mode-coupling theory indicated perfect agreement among experimental data and theory. Our results are consistent with the existence of a second critical point of water.

  3. Confined Water as Model of Supercooled Water.

    PubMed

    Cerveny, Silvina; Mallamace, Francesco; Swenson, Jan; Vogel, Michael; Xu, Limei

    2016-07-13

    Water in confined geometries has obvious relevance in biology, geology, and other areas where the material properties are strongly dependent on the amount and behavior of water in these types of materials. Another reason to restrict the size of water domains by different types of geometrical confinements has been the possibility to study the structural and dynamical behavior of water in the deeply supercooled regime (e.g., 150-230 K at ambient pressure), where bulk water immediately crystallizes to ice. In this paper we give a short review of studies with this particular goal. However, from these studies it is also clear that the interpretations of the experimental data are far from evident. Therefore, we present three main interpretations to explain the experimental data, and we discuss their advantages and disadvantages. Unfortunately, none of the proposed scenarios is able to predict all the observations for supercooled and glassy bulk water, indicating that either the structural and dynamical alterations of confined water are too severe to make predictions for bulk water or the differences in how the studied water has been prepared (applied cooling rate, resulting density of the water, etc.) are too large for direct and quantitative comparisons. PMID:26940794

  4. Transport properties of supercooled confined water

    NASA Astrophysics Data System (ADS)

    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.

  5. Quantum effects in the dynamics of deeply supercooled water

    SciTech Connect

    Agapov, Alexander L.; Kolesnikov, Alexander I.; Novikov, Vladimir N.; Richert, Ranko; Sokolov, Alexei P

    2015-02-26

    In spite of its simple chemical structure, water remains one of the most puzzling liquids with many anomalies at low temperatures. Combining neutron scattering and dielectric relaxation spectroscopy, we show that quantum fluctuations are not negligible in deeply supercooled water. Our dielectric measurements reveal the anomalously weak temperature dependence of structural relaxation in vapor-deposited water close to the glass transition temperature Tg~136K. We demonstrate that this anomalous behavior can be explained well by quantum effects. In conclusion, these results have significant implications for our understanding of water dynamics.

  6. Quantum effects in the dynamics of deeply supercooled water

    DOE PAGESBeta

    Agapov, Alexander L.; Kolesnikov, Alexander I.; Novikov, Vladimir N.; Richert, Ranko; Sokolov, Alexei P

    2015-02-26

    In spite of its simple chemical structure, water remains one of the most puzzling liquids with many anomalies at low temperatures. Combining neutron scattering and dielectric relaxation spectroscopy, we show that quantum fluctuations are not negligible in deeply supercooled water. Our dielectric measurements reveal the anomalously weak temperature dependence of structural relaxation in vapor-deposited water close to the glass transition temperature Tg~136K. We demonstrate that this anomalous behavior can be explained well by quantum effects. In conclusion, these results have significant implications for our understanding of water dynamics.

  7. Molecular Probe Dynamics Reveals Suppression of Ice-Like Regions in Strongly Confined Supercooled Water

    PubMed Central

    Banerjee, Debamalya; Bhat, Shrivalli N.; Bhat, Subray V.; Leporini, Dino

    2012-01-01

    The structure of the hydrogen bond network is a key element for understanding water's thermodynamic and kinetic anomalies. While ambient water is strongly believed to be a uniform, continuous hydrogen-bonded liquid, there is growing consensus that supercooled water is better described in terms of distinct domains with either a low-density ice-like structure or a high-density disordered one. We evidenced two distinct rotational mobilities of probe molecules in interstitial supercooled water of polycrystalline ice [Banerjee D, et al. (2009) ESR evidence for 2 coexisting liquid phases in deeply supercooled bulk water. Proc Natl Acad Sci USA 106: 11448–11453]. Here we show that, by increasing the confinement of interstitial water, the mobility of probe molecules, surprisingly, increases. We argue that loose confinement allows the presence of ice-like regions in supercooled water, whereas a tighter confinement yields the suppression of this ordered fraction and leads to higher fluidity. Compelling evidence of the presence of ice-like regions is provided by the probe orientational entropy barrier which is set, through hydrogen bonding, by the configuration of the surrounding water molecules and yields a direct measure of the configurational entropy of the same. We find that, under loose confinement of supercooled water, the entropy barrier surmounted by the slower probe fraction exceeds that of equilibrium water by the melting entropy of ice, whereas no increase of the barrier is observed under stronger confinement. The lower limit of metastability of supercooled water is discussed. PMID:23049747

  8. Accelerated dynamics of supercooled glycerol in soft confinement

    NASA Astrophysics Data System (ADS)

    Blochowicz, T.; Gouirand, E.; Fricke, A.; Spehr, T.; Stühn, B.; Frick, B.

    2009-06-01

    We investigate the dynamics of supercooled glycerol in a soft confinement within microemulsion droplets. The structure of the system is characterized by small-angle neutron scattering. We show that temperature-stable droplets establish a confinement, which may be varied in size from about 1 to 10 nm. Subsequently we focus on the dynamics of glass-forming glycerol confined within nanodroplets of different sizes. By combining neutron backscattering and time-of-flight for a broad dynamic range we obtain the incoherent intermediate scattering function S(q,t), which reveals increasingly accelerated dynamics as glycerol is confined to smaller droplets and for the relaxation times a crossover from Vogel-Fulcher behavior in the bulk to an Arrhenius law in confinement.

  9. More accurate X-ray scattering data of deeply supercooled bulk liquid water

    SciTech Connect

    Neuefeind, Joerg C; Benmore, Chris J; Weber, Richard; Paschek, Dietmar

    2011-01-01

    Deeply supercooled water droplets held container-less in an acoustic levitator are investigated with high energy X-ray scattering. The temperature dependence X-ray structure function is found to be non-linear. Comparison with two popular computer models reveals that structural changes are predicted too abrupt by the TIP5P model, while the rate of change predicted by TIP4P is in much better agreement with experiment. The abrupt structural changes predicted by the TIP5P model to occur in the temperature range between 260-240K as water approaches the homogeneous nucleation limit are unrealistic. Both models underestimate the distance between neighbouring oxygen atoms and overestimate the sharpness of the OO distance distribution, indicating that the strength of the H-bond is overestimated in these models.

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

    NASA Astrophysics Data System (ADS)

    Liu, L.; Faraone, A.; Mou, C.-Y.; Yen, C.-W.; Chen, S.-H.

    2004-11-01

    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 Å) and MCM-48-S (pore size 22 Å) using three QENS spectrometers of respective energy resolutions 1, 30, and 60 µeV, covering the temperature range from 325 to 200 K. Five quantities are extracted from the analysis: they are β, the stretch exponent characterizing the α-relaxation βγ, the exponent determining the power-law dependence of the relaxation time on Q; \\langle \\tau_{0} \\rangle , the Q-independent pre-factor for the average translational relaxation time; \\langle \\tau _{{\\mathrm {R}}_{1}} \\rangle , the relaxation time for the first-order rotational correlation function; and \\langle \\tau _{{\\mathrm {R}}_{2}} \\rangle , 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.

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

    NASA Astrophysics Data System (ADS)

    Kay, Bruce

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

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

    PubMed

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

    2014-11-21

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

  13. High-frequency propagating density fluctuations in deeply supercooled water: evidence of a single viscous relaxation.

    PubMed

    Aliotta, F; Gapiński, J; Pochylski, M; Ponterio, R C; Saija, F; Salvato, G; Vasi, C

    2013-02-01

    We performed a Brillouin scattering experiment on deeply supercooled water and compared the results with similar literature data obtained both at the same and at higher values of the exchanged wave vector. The whole set of available experimental data can be well reproduced with the use of the generalized hydrodynamic model where all the involved thermodynamic parameters are fixed to their literature values. On the contrary, the model based on the memory function approach generates the wrong estimates for measurables when the same values of the thermodynamic parameters are used. This result confirms our recent criticisms against the utilization of models originating from linear response theory [Phys. Rev. E 84, 051202 (2011)]. The inconsistency between models explains apparent discrepancies between the different conclusions on water acoustic behavior which may be found in the literature. We demonstrate that the observed behavior can be explained by assuming only a single relaxation process that is typical of any viscoelastic system. With all thermodynamics quantities fixed, the hydrodynamic description needs only two parameters to model the experimental data, namely, the relaxation time and the high-frequency limit of the sound velocity. The whole body of the experimental data can be well reproduced when the relaxation time behaves in an Arrhenian manner and the difference between the relaxed and not relaxed sound velocities is a constant. The high-frequency sound velocity is never higher than 2200 m/s. We conclude that, at least from experiments performed within the hydrodynamic regime, there is no indication for a fast sound close to the hypersonic velocity observed in ice. PMID:23496512

  14. Viscosity of deeply supercooled water and its coupling to molecular diffusion

    PubMed Central

    Dehaoui, Amine; Issenmann, Bruno; Caupin, Frédéric

    2015-01-01

    The viscosity of a liquid measures its resistance to flow, with consequences for hydraulic machinery, locomotion of microorganisms, and flow of blood in vessels and sap in trees. Viscosity increases dramatically upon cooling, until dynamical arrest when a glassy state is reached. Water is a notoriously poor glassformer, and the supercooled liquid crystallizes easily, making the measurement of its viscosity a challenging task. Here we report viscosity of water supercooled close to the limit of homogeneous crystallization. Our values contradict earlier data. A single power law reproduces the 50-fold variation of viscosity up to the boiling point. Our results allow us to test the Stokes–Einstein and Stokes–Einstein–Debye relations that link viscosity, a macroscopic property, to the molecular translational and rotational diffusion, respectively. In molecular glassformers or liquid metals, the violation of the Stokes–Einstein relation signals the onset of spatially heterogeneous dynamics and collective motions. Although the viscosity of water strongly decouples from translational motion, a scaling with rotational motion remains, similar to canonical glassformers. PMID:26378128

  15. Volume crossover in deeply supercooled water adiabatically freezing under isobaric conditions.

    PubMed

    Aliotta, Francesco; Giaquinta, Paolo V; Pochylski, Mikolaj; Ponterio, Rosina C; Prestipino, Santi; Saija, Franz; Vasi, Cirino

    2013-05-14

    The irreversible return of a supercooled liquid to stable thermodynamic equilibrium often begins as a fast process which adiabatically drives the system to solid-liquid coexistence. Only at a later stage will solidification proceed with the expected exchange of thermal energy with the external bath. In this paper we discuss some aspects of the adiabatic freezing of metastable water at constant pressure. In particular, we investigated the thermal behavior of the isobaric gap between the molar volume of supercooled water and that of the warmer ice-water mixture which eventually forms at equilibrium. The available experimental data at ambient pressure, extrapolated into the metastable region within the scheme provided by the reference IAPWS-95 formulation, show that water ordinarily expands upon (partially) freezing under isenthalpic conditions. However, the same scheme also suggests that, for increasing undercoolings, the volume gap is gradually reduced and eventually vanishes at a temperature close to the currently estimated homogeneous ice nucleation temperature. This behavior is contrasted with that of substances which do not display a volumetric anomaly. The effect of increasing pressures on the alleged volume crossover from an expanded to a contracted ice-water mixture is also discussed. PMID:23676053

  16. Volume crossover in deeply supercooled water adiabatically freezing under isobaric conditions

    NASA Astrophysics Data System (ADS)

    Aliotta, Francesco; Giaquinta, Paolo V.; Pochylski, Mikolaj; Ponterio, Rosina C.; Prestipino, Santi; Saija, Franz; Vasi, Cirino

    2013-05-01

    The irreversible return of a supercooled liquid to stable thermodynamic equilibrium often begins as a fast process which adiabatically drives the system to solid-liquid coexistence. Only at a later stage will solidification proceed with the expected exchange of thermal energy with the external bath. In this paper we discuss some aspects of the adiabatic freezing of metastable water at constant pressure. In particular, we investigated the thermal behavior of the isobaric gap between the molar volume of supercooled water and that of the warmer ice-water mixture which eventually forms at equilibrium. The available experimental data at ambient pressure, extrapolated into the metastable region within the scheme provided by the reference IAPWS-95 formulation, show that water ordinarily expands upon (partially) freezing under isenthalpic conditions. However, the same scheme also suggests that, for increasing undercoolings, the volume gap is gradually reduced and eventually vanishes at a temperature close to the currently estimated homogeneous ice nucleation temperature. This behavior is contrasted with that of substances which do not display a volumetric anomaly. The effect of increasing pressures on the alleged volume crossover from an expanded to a contracted ice-water mixture is also discussed.

  17. Viscosity of deeply supercooled water and its coupling to molecular diffusion.

    PubMed

    Dehaoui, Amine; Issenmann, Bruno; Caupin, Frédéric

    2015-09-29

    The viscosity of a liquid measures its resistance to flow, with consequences for hydraulic machinery, locomotion of microorganisms, and flow of blood in vessels and sap in trees. Viscosity increases dramatically upon cooling, until dynamical arrest when a glassy state is reached. Water is a notoriously poor glassformer, and the supercooled liquid crystallizes easily, making the measurement of its viscosity a challenging task. Here we report viscosity of water supercooled close to the limit of homogeneous crystallization. Our values contradict earlier data. A single power law reproduces the 50-fold variation of viscosity up to the boiling point. Our results allow us to test the Stokes-Einstein and Stokes-Einstein-Debye relations that link viscosity, a macroscopic property, to the molecular translational and rotational diffusion, respectively. In molecular glassformers or liquid metals, the violation of the Stokes-Einstein relation signals the onset of spatially heterogeneous dynamics and collective motions. Although the viscosity of water strongly decouples from translational motion, a scaling with rotational motion remains, similar to canonical glassformers. PMID:26378128

  18. Structure and dynamics of supercooled water in neutral confinements

    NASA Astrophysics Data System (ADS)

    Klameth, F.; Vogel, M.

    2013-04-01

    We perform molecular dynamics simulations to study the structure and dynamics of liquid water in neutral nanopores, which are generated by pinning a suitable subset of water molecules in an equilibrium configuration of a bulk system. It is found that such neutral confinement does not disturb the structure of water, in particular, the local tetrahedral order, while it imposes a pronounced spatial inhomogeneity on the dynamics of water. Specifically, when the pore wall is approached, hopping motion sets in and water dynamics slows down. We show that the logarithm of the correlation time is an exponential function of the distance to the wall, indicating a tremendous gradient of water mobility across the confinement. Upon cooling, the length scale associated with this exponential distance dependence and, thus, the range of the wall effect increases, at least down to the critical temperature of mode coupling theory, Tc. Also, the temperature dependence of water dynamics varies across the pore, i.e., fragility is high in the pore center, while it is low near the pore wall. Due to all these effects, time-temperature superposition is violated. Our observations for a neutral confinement reveal that specific interactions at hydrophilic or hydrophobic walls are not the main cause of spatially inhomogeneous dynamics of confined water. In view of similarities with the behavior of Lennard-Jones liquids in neutral confinements, one may rather speculate that the effects observed for confined water are general and result from the existence of a static contribution to the energy landscape, which is imprinted by an immobile environment.

  19. Communication: Local structure-mobility relationships of confined fluids reverse upon supercooling.

    PubMed

    Bollinger, Jonathan A; Jain, Avni; Carmer, James; Truskett, Thomas M

    2015-04-28

    We examine the structural and dynamic properties of confined binary hard-sphere mixtures designed to mimic realizable colloidal thin films. Using computer simulations, governed by either Newtonian or overdamped Langevin dynamics, together with other techniques including a Fokker-Planck equation-based method, we measure the position-dependent and average diffusivities of particles along structurally isotropic and inhomogeneous dimensions of the fluids. At moderate packing fractions, local single-particle diffusivities normal to the direction of confinement are higher in regions of high total packing fraction; however, these trends are reversed as the film is supercooled at denser average packings. Auxiliary short-time measurements of particle displacements mirror data obtained for experimental supercooled colloidal systems. We find that average dynamics can be approximately predicted based on the distribution of available space for particle insertion across orders of magnitude in diffusivity regardless of the governing microscopic dynamics. PMID:25933745

  20. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering.

    PubMed

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-01

    Water's behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (αp) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated αp peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface. PMID:26342380

  1. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    SciTech Connect

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-07

    The behavior of water near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. Moreover, by monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (alpha(p)) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. Additionally, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated ap peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.

  2. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    DOE PAGESBeta

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-07

    The behavior of water near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. Moreover, by monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed thatmore » the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (alpha(p)) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. Additionally, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated ap peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.« less

  3. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    NASA Astrophysics Data System (ADS)

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U.-Ser; Mou, Chung-Yuan

    2015-09-01

    Water's behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (αp) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated αp peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.

  4. Density of hydrophobically confined deeply cooled water investigated by small angle X-ray scattering

    SciTech Connect

    Liu, Kao-Hsiang; Zhang, Yang; Jeng, U-Ser; Mou, Chung-Yuan

    2015-09-07

    Water’s behavior near hydrophobic surfaces has attracted great attention due to chemical and geological applications. Here, we report small angle X-ray scattering (SAXS) studies of water confined in the hydrophobic nanoporous carbon material, CMK-1-14, from ambient to deeply cooled temperatures. By monitoring the scattering intensity of the first Bragg peak, which is directly related to the scattering length density contrast between the carbon matrix and the confined water, the average density of the hydrophobically confined water was determined from 300 K to 150 K at ambient pressure. Furthermore, differential scanning calorimetry and X-ray diffraction measurements showed that the majority of such hydrophobically confined water did not crystallize in the investigated temperature range. By exploiting the fast speed of SAXS measurements and the continuous temperature ramping, the average density profile and the deduced thermal expansion coefficient (α{sub p}) were obtained. We found that the well-known density maximum of water at 277 K downshifted to 260 K, and the density minimum which has been observed in hydrophilic confinement disappeared. In addition, the previously measured large density decreasing of 18% at low temperature was recalibrated to a more reasonable 10% instead. Consequently, the recalculated α{sub p} peak was found to be quite similar to that of the water confined in hydrophilic MCM-41-S-15 suggesting an intrinsic property of water, which does not sensitively depend on the confinement surface.

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

    SciTech Connect

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Metal-organic frameworks as host materials of confined supercooled liquids

    NASA Astrophysics Data System (ADS)

    Fischer, J. K. H.; Sippel, P.; Denysenko, D.; Lunkenheimer, P.; Volkmer, D.; Loidl, A.

    2015-10-01

    In this work, we examine the use of metal-organic framework (MOF) systems as host materials for the investigation of glassy dynamics in confined geometry. We investigate the confinement of the molecular glass former glycerol in three MFU-type MOFs with different pore sizes (MFU stands for "Metal-Organic Framework Ulm-University") and study the dynamics of the confined liquid via dielectric spectroscopy. In accord with previous reports on confined glass formers, we find different degrees of deviations from bulk behavior depending on pore size, demonstrating that MOFs are well-suited host systems for confinement investigations.

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

    PubMed

    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 (100-115 K) near the glass transition temperature, T(g) (103 K). Layered films, consisting of CH(3)OH and CD(3)OH, 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 T(g). 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. PMID:20370128

  9. Thermodynamic, structural, and dynamic properties of supercooled water confined in mesoporous MCM-41 studied with calorimetric, neutron diffraction, and neutron spin echo measurements

    NASA Astrophysics Data System (ADS)

    Yoshida, Koji; Yamaguchi, Toshio; Kittaka, Shigeharu; Bellissent-Funel, Marie-Claire; Fouquet, Peter

    2008-08-01

    Thermodynamic, structural, and dynamic properties of heavy water (D2O) confined in mesoporous silica glass MCM-41 C10, C12, and C14 were investigated by differential scanning calorimetry, neutron diffraction, and neutron spin echo (NSE) measurements, respectively. The DSC data showed that no crystallization of D2O confined in C10 occurs in a temperature range between 298 and 180 K, and that crystalline ice is formed at 204 and 221 K for C12 and C14, respectively. For C10, the neutron radial distribution functions of confined D2O suggested a structural change in the supercooled state between 223 and 173 K. For C10 sample, it has been found that the tetrahedral-like water structure is partially enhanced in the central part of pores at 173 K. For all the samples, the intermediate scattering functions from the NSE measurements are fitted by the Kohlrausch-Williams-Watts stretched exponential function which implies that confined supercooled D2O exhibits a wide distribution of relaxation times. For C10, C12, and C14 samples, between 298 and 240 K, the relaxation times of supercooled D2O follow remarkably well the Vogel-Fulcher-Tamman equation; for C10 sample, below 240 K, the relaxation times of nonfreezing D2O show an Arrhenius type behavior. From the present experimental results on calorimetric, structural, and dynamic properties, it has been concluded that supercooled D2O confined in MCM-41 C10 experiences a transition from high-density to low-density hydrogen-bonded structure at around 229 K.

  10. Heterogeneous nucleation of ice from supercooled NaCl solution confined in porous cement paste

    NASA Astrophysics Data System (ADS)

    Zeng, Qiang; Li, Kefei; Fen-Chong, Teddy

    2015-01-01

    Clarifying the nucleation process of chloride-based deicing salt solution (e.g., NaCl solution) confined in cement-based porous materials remains an important issue to understand its detrimental effects on material substrates. In this study, the pore structures of hardened cement pastes were characterized by mercury-intrusion and nitrogen-sorption porosimetry. The ice nucleation temperature of NaCl solution of different concentrations confined in the hardened cement pastes was measured and analyzed by classical heterogeneous nucleation theory. The kinetic factor, contact-angle factor including the contact angle between ice and the substrate were evaluated. The results revealed that the contact angle between ice and the substrate showed the minimum value when adding 3% NaCl into water. The heterogeneous ice nucleation rates were found to be proportional to the water activity shifts.

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

    DOE PAGESBeta

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

    2015-12-03

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

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

    SciTech Connect

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

    2015-12-03

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

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

    PubMed

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

    2015-06-01

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

  14. The Dynamics of Supercooled Water

    NASA Astrophysics Data System (ADS)

    Mallamace, Francesco

    2011-03-01

    We present 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 nano-meter-scale environments (nano-tubes and the protein hydration water) and in bulk solutions. 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. In particular 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 70K below the temperature of the density maximum. In our opinion these results represent the experimental proofs of the validity of the LLPT hypothesis.

  15. Supercooled Water in Supramolecular Hydrogels

    NASA Astrophysics Data System (ADS)

    Wiener, Clinton; Vogt, Bryan; Weiss, R. A.

    The suppression of water crystallization with appreciable water supercooling is challenging due to its large enthalpy of fusion. A common theme to supercool water is to confine the water in the pores of microporous/mesoporous solids where mechanical confinement prevents water crystallization. Nature takes a different approach with crystallization suppression through a combination of preferential adsorption on ice nuclei and confinement between hydrophobic residues using organic components only. Here, we demonstrate that mechanically robust confinement within a hard material is not necessary to significantly supercool water. In this case, a supramolecular hydrogel, based on a random amphiphilic copolymer, is used to provide soft confinement of water between the hydrophobic aggregates with an interdomain spacing <8 nm. Small angle neutron scattering (SANS) provides insight into the structural evolution of the supramolecular structure of the hydrogel on supercooling. The structural changes are sensitive to the composition of the copolymer as determined by contrast variation SANS. Similarly, the dynamics of both the copolymer and water are probed using quasielastic neutron scattering (QENS). Using QENS, a highly mobile water phase (tau ~23 ps) is identified to be present even when slowly cooling to as low as 220K.

  16. Supercooled water and the kinetic glass transition

    NASA Astrophysics Data System (ADS)

    Sciortino, F.; Gallo, P.; Tartaglia, P.; Chen, S.-H.

    1996-12-01

    We present a molecular-dynamics study of the self-dynamics of water molecules in deeply supercooled liquid states. We find that the decay of single-particle dynamics correlation functions is characterized by a fast initial relaxation toward a plateau and by a region of self-similar dynamics, followed at late times by a stretched exponential decay. We interpret such results in the framework of the mode-coupling theory for supercooled liquids. We relate the apparent anomalies of the transport coefficients in water on lowering the temperature to the formation of cages and to the associated slow dynamics resulting from the presence of long-lived molecular cages. The so-called critical Angell temperature in supercooled water could thus be interpreted as kinetic glass transition temperature, relaxing the need of a thermodynamic singularity for the explanation of the anomalies of liquid water.

  17. Evidence of the existence of the high-density and low-density phases in deeply-cooled confined heavy water under high pressures

    SciTech Connect

    Wang, Zhe; Chen, Sow-Hsin; Liu, Kao-Hsiang; Harriger, Leland; Leão, Juscelino B.

    2014-07-07

    The average density of D{sub 2}O confined in a nanoporous silica matrix (MCM-41-S) is studied with neutron scattering. We find that below ∼210 K, the pressure-temperature plane of the system can be divided into two regions. The average density of the confined D{sub 2}O in the higher-pressure region is about 16% larger than that in the lower-pressure region. These two regions could represent the so-called “low-density liquid” and “high-density liquid” phases. The dividing line of these two regions, which could represent the associated 1st order liquid-liquid transition line, is also determined.

  18. The Ultimate Fate of Supercooled Liquids

    PubMed Central

    Stevenson, Jacob D.; Wolynes, Peter G.

    2011-01-01

    In recent years it has become widely accepted that a dynamical length scale ξα plays an important role in supercooled liquids near the glass transition. We examine the implications of the interplay between the growing ξα and the size of the crystal nucleus, ξM, which shrinks on cooling. We argue that at low temperatures where ξα > ξM a new crystallization mechanism emerges enabling rapid development of a large scale web of sparsely connected crystallinity. Though we predict this web percolates the system at too low a temperature to be easily seen in the laboratory, there are noticeable residual effects near the glass transition that can account for several previously observed unexplained phenomena of deeply supercooled liquids including Fischer clusters, and anomalous crystal growth near Tg. PMID:21171637

  19. An ideal glass transition in supercooled water?

    NASA Astrophysics Data System (ADS)

    Sciortino, F.; Chen, S. H.; Gallo, P.; Tartaglia, P.

    Analyzing recent molecular dynamics simulations in deeply supercooled liquid states, we have found that the single particle dynamics in water can be interpreted in terms of Mode Coupling Theory, in its so-called ideal formulation. In this paper we review such evidence and discuss the relevance of this finding for the debated thermodynamic behavior of supercooled water. The experimental apparent power-law behavior of the transport coefficients in water, diverging or going to zero at the so-called Angell temperature could indeed be interpreted as a kinetic, as distinct from thermodynamic, phenomena. This finding removes the need of a thermodynamic singularity for the explanation of the anomalies of liquid water. We also comment on the development of a significant harmonic dynamics on cooling the liquid, which could indicate a transition from a fragile to a strong behavior in liquid water.

  20. Dynamic crossover in deeply cooled water confined in MCM-41 at 4 kbar and its relation to the liquid-liquid transition hypothesis.

    PubMed

    Wang, Zhe; Le, Peisi; Ito, Kanae; Leão, Juscelino B; Tyagi, Madhusudan; Chen, Sow-Hsin

    2015-09-21

    With quasi-elastic neutron scattering, we study the single-particle dynamics of the water confined in a hydrophilic silica material, MCM-41, at 4 kbar. A dynamic crossover phenomenon is observed at 219 K. We compare this dynamic crossover with the one observed at ambient pressure and find that (a) above the crossover temperature, the temperature dependence of the characteristic relaxation time at ambient pressure exhibits a more evident super-Arrhenius behavior than that at 4 kbar. Especially, at temperatures below about 230 K, the relaxation time at 4 kbar is even smaller than that at ambient pressure. This feature is different from many other liquids. (b) Below the crossover temperature, the Arrhenius behavior found at ambient pressure has a larger activation energy compared to the one found at 4 kbar. We ascribe the former to the difference between the local structure of the low-density liquid (LDL) phase and that of the high-density liquid (HDL) phase, and the latter to the difference between the strength of the hydrogen bond of the LDL and that of the HDL. Therefore, we conclude that the phenomena observed in this paper are consistent with the LDL-to-HDL liquid-liquid transition hypothesis. PMID:26395720

  1. Dynamic crossover in deeply cooled water confined in MCM-41 at 4 kbar and its relation to the liquid-liquid transition hypothesis

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Le, Peisi; Ito, Kanae; Leão, Juscelino B.; Tyagi, Madhusudan; Chen, Sow-Hsin

    2015-09-01

    With quasi-elastic neutron scattering, we study the single-particle dynamics of the water confined in a hydrophilic silica material, MCM-41, at 4 kbar. A dynamic crossover phenomenon is observed at 219 K. We compare this dynamic crossover with the one observed at ambient pressure and find that (a) above the crossover temperature, the temperature dependence of the characteristic relaxation time at ambient pressure exhibits a more evident super-Arrhenius behavior than that at 4 kbar. Especially, at temperatures below about 230 K, the relaxation time at 4 kbar is even smaller than that at ambient pressure. This feature is different from many other liquids. (b) Below the crossover temperature, the Arrhenius behavior found at ambient pressure has a larger activation energy compared to the one found at 4 kbar. We ascribe the former to the difference between the local structure of the low-density liquid (LDL) phase and that of the high-density liquid (HDL) phase, and the latter to the difference between the strength of the hydrogen bond of the LDL and that of the HDL. Therefore, we conclude that the phenomena observed in this paper are consistent with the LDL-to-HDL liquid-liquid transition hypothesis.

  2. Dynamic crossover in deeply cooled water confined in MCM-41 at 4 kbar and its relation to the liquid-liquid transition hypothesis

    SciTech Connect

    Wang, Zhe; Le, Peisi; Ito, Kanae; Chen, Sow-Hsin; Leão, Juscelino B.; Tyagi, Madhusudan

    2015-09-21

    With quasi-elastic neutron scattering, we study the single-particle dynamics of the water confined in a hydrophilic silica material, MCM-41, at 4 kbar. A dynamic crossover phenomenon is observed at 219 K. We compare this dynamic crossover with the one observed at ambient pressure and find that (a) above the crossover temperature, the temperature dependence of the characteristic relaxation time at ambient pressure exhibits a more evident super-Arrhenius behavior than that at 4 kbar. Especially, at temperatures below about 230 K, the relaxation time at 4 kbar is even smaller than that at ambient pressure. This feature is different from many other liquids. (b) Below the crossover temperature, the Arrhenius behavior found at ambient pressure has a larger activation energy compared to the one found at 4 kbar. We ascribe the former to the difference between the local structure of the low-density liquid (LDL) phase and that of the high-density liquid (HDL) phase, and the latter to the difference between the strength of the hydrogen bond of the LDL and that of the HDL. Therefore, we conclude that the phenomena observed in this paper are consistent with the LDL-to-HDL liquid-liquid transition hypothesis.

  3. The glass transition and relaxation behavior of bulk water and a possible relation to confined water

    NASA Astrophysics Data System (ADS)

    Swenson, Jan; Teixeira, José

    2010-01-01

    Due to the widespread importance of water and the difficulty to study it in the so-called no man's land between 150 and 235 K, deeply supercooled bulk water is currently heavily debated. It speculates about its properties from extrapolations of experimental data on bulk water above 235 K and below 150 K, computer simulations, and experiments on confined water for which the finite size effects may prevent crystallization in the no man's land. However, it is far from obvious how experimental data on bulk water should be extrapolated to the temperature range of the no man's land or how relevant results from computer simulations and studies of confined water are for bulk water. In this paper the structural and dynamical properties of supercooled bulk water are tried to be understood from experimental results on confined water and comparisons with bulk water. We propose that a similar crossover from a high temperature α-relaxation to a low temperature β-relaxation occurs also for bulk water but at a higher temperature than for confined water due to the larger average number of hydrogen bonds between the water molecules in bulk water. In the case of bulk water the crossover is expected to occur around the critical temperature Ts≈228 K when the buildup of an icelike tetrahedral network structure is completed. The proposed interpretation is the simplest one that is able to explain many of the peculiar properties of supercooled water.

  4. The Boson peak in supercooled water.

    PubMed

    Kumar, Pradeep; Wikfeldt, K Thor; Schlesinger, Daniel; Pettersson, Lars G M; Stanley, H Eugene

    2013-01-01

    We perform extensive molecular dynamics simulations of the TIP4P/2005 model of water to investigate the origin of the Boson peak reported in experiments on supercooled water in nanoconfined pores, and in hydration water around proteins. We find that the onset of the Boson peak in supercooled bulk water coincides with the crossover to a predominantly low-density-like liquid below the Widom line TW. The frequency and onset temperature of the Boson peak in our simulations of bulk water agree well with the results from experiments on nanoconfined water. Our results suggest that the Boson peak in water is not an exclusive effect of confinement. We further find that, similar to other glass-forming liquids, the vibrational modes corresponding to the Boson peak are spatially extended and are related to transverse phonons found in the parent crystal, here ice Ih. PMID:23771033

  5. Preventing Supercooling Of Gallium

    NASA Technical Reports Server (NTRS)

    Massucco, Arthur A.; Wenghoefer, Hans M.; Wilkins, Ronnie

    1994-01-01

    Principle of heterogeneous nucleation exploited to prevent gallium from supercooling, enabling its use as heat-storage material that crystallizes reproducibly at its freezing or melting temperature of 29 to 30 degrees C. In original intended application, gallium used as heat-storage material in gloves of space suits. Terrestrial application lies in preparation of freezing-temperature reference samples for laboratories. Principle of heterogeneous nucleation also exploited similarly in heat pipes filled with sodium.

  6. Supercooled liquid water Estimation Tool

    Energy Science and Technology Software Center (ESTSC)

    2012-05-04

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

  7. Deeply virtual Compton scattering

    NASA Astrophysics Data System (ADS)

    Marukyan, Hrachya

    2015-11-01

    This paper reviews the experimental measurements in the field of deeply virtual Compton scattering and related theoretical efforts aimed for the extraction of generalized parton distributions, objects, describing the three-dimensional structure of nucleons and nuclei. The future experiments and theoretical expectations are also considered.

  8. Supercooling Water in Cylindrical Capsules

    NASA Astrophysics Data System (ADS)

    Guzman, J. J. Milón; Braga, S. L.

    2005-11-01

    An experimental apparatus was developed to investigate the supercooling phenomenon of water inside cylindrical capsules used for a cold storage process. The coolant is a water-alcohol mixture controlled by a constant temperature bath (CTB). Temperatures varying with time are measured inside and outside the capsule. Cylinders with an internal diameter and thickness of 45 and 1.5 mm, respectively, were made from four different materials: acrylic, PVC, brass, and aluminum. The supercooling period of the water and the nucleation temperature were investigated for different coolant temperatures. The supercooling and nucleation probabilities are shown as a function of the coolant temperature for the four different materials.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  10. Supercooled water escaping from metastability

    PubMed Central

    Aliotta, Francesco; Giaquinta, Paolo V.; Ponterio, Rosina C.; Prestipino, Santi; Saija, Franz; Salvato, Gabriele; Vasi, Cirino

    2014-01-01

    The return of supercooled water to a stable equilibrium condition is an irreversible process which, in large enough samples, takes place adiabatically. We investigated this phenomenon in water by fast imaging techniques. As water freezes, large energy and density fluctuations promote the spatial coexistence of solid and liquid phases at different temperatures. Upon synchronously monitoring the time evolution of the local temperature, we observed a sharp dynamic transition between a fast and a slow decay regime at about 266.6 K. We construe the observed phenomenon in terms of the temperature dependence of heat transfers from solid and liquid volumes already at their bulk coexistence temperature towards adjacent still supercooled liquid regions. These findings can be justified by observing that convective motions induced by thermal gradients in a supercooled liquid near coexistence are rapidly suppressed as the nucleated solid fraction overcomes, at low enough temperatures, a characteristic percolation threshold. PMID:25427603

  11. First-order transition in confined water between high-density liquid and low-density amorphous phases.

    PubMed

    Koga, K; Tanaka, H; Zeng, X C

    2000-11-30

    Supercooled water and amorphous ice have a rich metastable phase behaviour. In addition to transitions between high- and low-density amorphous solids, and between high- and low-density liquids, a fragile-to-strong liquid transition has recently been proposed, and supported by evidence from the behaviour of deeply supercooled bilayer water confined in hydrophilic slit pores. Here we report evidence from molecular dynamics simulations for another type of first-order phase transition--a liquid-to-bilayer amorphous transition--above the freezing temperature of bulk water at atmospheric pressure. This transition occurs only when water is confined in a hydrophobic slit pore with a width of less than one nanometre. On cooling, the confined water, which has an imperfect random hydrogen-bonded network, transforms into a bilayer amorphous phase with a perfect network (owing to the formation of various hydrogen-bonded polygons) but no long-range order. The transition shares some characteristics with those observed in tetrahedrally coordinated substances such as liquid silicon, liquid carbon and liquid phosphorus. PMID:11117739

  12. Thermodynamic geometry of supercooled water.

    PubMed

    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. PMID:25871088

  13. Crystallization of supercooled solutions. [atmosphere

    NASA Technical Reports Server (NTRS)

    Harrison, K.; Hallett, John

    1988-01-01

    Crystallization of uniformly supercooled solutions (Na2SO4, NaCl, H2SO4, HNO3, HCl) was studied. It is shown how crystal growth velocity and habit depend on solution and concentration. The segregation coefficient for the solute in ice is measured by analysis of ice and solution, separated immediately after initial freezing, at different supercoolings. Subsequent solidification gives ion rejection at a varying rate depending on the geometry of the freezing, and may result in separation of hydrates, particularly when the initial concentration is high, as in haze (inactivated) droplets and low temperatures found in the Antarctic stratosphere. Electrical effects associated with rapid freezing are also investigated. Results suggest that more extensive measurements need to be made in solutions at different supercoolings, and that substantial electrical effects may be present for higher concentrations under these conditions. Damage to vegetation could occur under specific conditions as concentrated solutions (possibly H2SO4) are rejected in the freezing of rime or dew.

  14. Diffusion and viscosity in a supercooled polydisperse system

    NASA Astrophysics Data System (ADS)

    Murarka, Rajesh K.; Bagchi, Biman

    2003-05-01

    We have carried out extensive molecular dynamics simulations of a supercooled polydisperse Lennard-Jones liquid with large variations in temperature at a fixed pressure. The particles in the system are considered to be polydisperse in both size and mass. The temperature dependence of dynamical properties such as the viscosity (η) and the self-diffusion coefficients (Di) of different size particles is studied. Both viscosity and diffusion coefficients show super-Arrhenius temperature dependence and fit well to the well-known Vogel-Fulcher-Tammann equation. Within the temperature range investigated, the value of Angell’s fragility parameter (D≈1.4) classifies the present system as a very fragile liquid. The critical temperature for diffusion (TDio) increases with the size of the particles. The critical temperature for viscosity (Tηo) is larger than that for diffusion, and sizable deviations appear for the smaller size particles, implying a decoupling of translational diffusion from viscosity in deeply supercooled liquids. Indeed, the diffusion shows markedly non-Stokesian behavior at low temperatures where a highly nonlinear dependence on size is observed. An inspection of the trajectories of the particles shows that at low temperatures the motions of both the smallest and largest size particles are discontinuous (jump type). However, the crossover from continuous Brownian to large length hopping motion takes place at shorter time scales for the smaller size particles.

  15. Computer simulation study of structure and dynamics of supercooled water in silica nanopores

    NASA Astrophysics Data System (ADS)

    Kuon, Nicholas; Ladanyi, Branka

    2014-03-01

    In narrow hydrophilic pores, interactions with pore walls and confinement dimensions allow water to remain liquid well below the normal freezing point. We investigate the properties of nanoconfined supercooled water by means of molecular simulation. The focus of our study is confinement in approximately cylindrical silica pores, with diameters in the 20-40 Å range, a model for MCM-41 materials. We use Gibbs-ensemble Monte Carlo method to determine water density in the pores in equilibrium with the bulk and molecular dynamics simulation to study the properties of confined water. We study the translational and rotational mobilities of molecules in different interfacial layers and the effects on water dynamics of interfacial hydrogen bonding. We make contact with quasi-elastic neutron scattering experiments on supercooled water in MCM-14 silica pores by calculating and analyzing self-intermediate scattering functions of water hydrogens. This research was supported by NSF grant number 1213682.

  16. Thermal Conductivity in Supercooled Water

    NASA Astrophysics Data System (ADS)

    Biddle, John; Holten, Vincent; Sengers, Jan; Anisimov, Mikhail

    2013-03-01

    The heat capacity of supercooled water, measured down to -37 C, shows an anomalous increase as temperature decreases. The thermal diffusivity, the ratio of thermal conductivity and the heat capacity per unit volume, shows a decrease. These anomalies may be associated with a hypothetical liquid-liquid critical point in metastable water below the line of homogeneous nucleation. The data suggest that the thermal conductivity does not show a significant critical enhancement, in contrast to what is observed near the vapor-liquid critical point. We have used mode-coupling theory to investigate the possible effect of critical fluctuations on the thermal conductivity of supercooled water, and shown that indeed this effect would be too small to be measurable at experimentally accessible temperatures. We discuss physical reasons for the striking difference between the vapor-liquid and liquid-liquid critical enhancements of thermal conductivity in water. We also discuss the discrepancy between the thermal conductivity calculated from experimental data and that obtained by computer simulations of the TIP5P water-like model. American Chemical Society Petroleum Research Fund Grant No. 52666-ND6

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Mixing it up - Measuring diffusion in supercooled liquid solutions of methanol and ethanol at temperatures near the glass transition

    SciTech Connect

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

    2011-03-17

    Do liquid mixtures, cooled to temperatures below their freezing point, behave as normal liquids? We address this question using nanoscale films of methanol and ethanol supercooled liquid solutions of varying composition (7 -93% methanol) at temperatures near their glass transition,Tg. The permeation of Kr through these films is used to determine the diffusivities of the supercooled liquid mixtures. We find that the temperature dependent diffusivities of the mixtures are well-fit by a Vogel-Fulcher-Tamman equation indicating that the mixtures exhibit fragile behavior at temperatures just above their Tg. Further, for a given temperature, the composition dependent diffusivity is well-fit by a Vignes-type equation, i.e. the diffusivity of any mixture can be predicted using an exponential weighting of the diffusion of the pure methanol and ethanol diffusivities. These results show that deeply supercooled liquid mixtures can be used to provide valuable insight into the properties of normal liquid mixtures.

  19. Simulations of spontaneous phase transitions in large, deeply supercooled clusters of SeF{sub 6}

    SciTech Connect

    Chushak, Y.G.; Bartell, L.S.

    1999-12-16

    The crystallization and subsequent solid-state transitions in a series of large clusters of SeF{sub 6} of two sizes have been studied by molecular dynamics simulations at constant temperature. Several diagnostic methods were applied to monitor molecular details of the clusters' structures and their evolution with time. The behavior of 12 liquid clusters with 725 molecules and 10 with 1,722 molecules was examined at 140 and 130 K. During the nanosecond runs of the simulations all of these clusters froze, initially to the bcc or a related but distorted structure. At the higher temperature all but one of the larger clusters underwent a transition to the monoclinic structure whereas all but one of the smaller clusters remained bcc. At the lower temperature all of the smaller clusters ultimately transformed, usually quite abruptly, to the monoclinic structure. In the case of the larger clusters a transition to the monoclinic phase was observed at 140 K whereas at 130 K, besides the monoclinic structure, the orthorhombic or a mixture of orthorhombic and monoclinic phases was obtained in a few clusters. Many of the larger frozen clusters were polycrystalline while the smaller ones were single crystals. How these results relate to Kaschiev's criterion for mononuclear vs polynuclear growth is discussed, and the time dependence of crystal growth was found to agree well with the Kolmogorov-Johnson-Mehl-Avrami equations. Growth rates of the bcc phase were in reasonable agreement with Turnbull's theory. Simulations of solid-state transitions from clusters prepared to have a well-ordered bcc configuration clearly indicate a lower nucleation rate for the low-energy phase than in a cluster with grain boundaries and/or despite the fact that surfaces of clusters tend to be disordered and melt at significantly lower temperatures than their cores. Such a behavior has also been reported for simulations of monatomic clusters.

  20. Crystallization of Lennard-Jones nanodroplets: From near melting to deeply supercooled.

    PubMed

    Malek, Shahrazad M A; Morrow, Gregory P; Saika-Voivod, Ivan

    2015-03-28

    We carry out molecular dynamics (MD) and Monte Carlo (MC) simulations to characterize nucleation in liquid clusters of 600 Lennard-Jones particles over a broad range of temperatures. We use the formalism of mean first-passage times to determine the rate and find that Classical Nucleation Theory (CNT) predicts the rate quite well, even when employing simple modelling of crystallite shape, chemical potential, surface tension, and particle attachment rate, down to the temperature where the droplet loses metastability and crystallization proceeds through growth-limited nucleation in an unequilibrated liquid. Below this crossover temperature, the nucleation rate is still predicted when MC simulations are used to directly calculate quantities required by CNT. Discrepancy in critical embryo sizes obtained from MD and MC arises when twinned structures with five-fold symmetry provide a competing free energy pathway out of the critical region. We find that crystallization begins with hcp-fcc stacked precritical nuclei and differentiation to various end structures occurs when these embryos become critical. We confirm that using the largest embryo in the system as a reaction coordinate is useful in determining the onset of growth-limited nucleation and show that it gives the same free energy barriers as the full cluster size distribution once the proper reference state is identified. We find that the bulk melting temperature controls the rate, even though the solid-liquid coexistence temperature for the droplet is significantly lower. The value of surface tension that renders close agreement between CNT and direct rate determination is significantly lower than what is expected for the bulk system. PMID:25833595

  1. Crystallization of Lennard-Jones nanodroplets: From near melting to deeply supercooled

    NASA Astrophysics Data System (ADS)

    Malek, Shahrazad M. A.; Morrow, Gregory P.; Saika-Voivod, Ivan

    2015-03-01

    We carry out molecular dynamics (MD) and Monte Carlo (MC) simulations to characterize nucleation in liquid clusters of 600 Lennard-Jones particles over a broad range of temperatures. We use the formalism of mean first-passage times to determine the rate and find that Classical Nucleation Theory (CNT) predicts the rate quite well, even when employing simple modelling of crystallite shape, chemical potential, surface tension, and particle attachment rate, down to the temperature where the droplet loses metastability and crystallization proceeds through growth-limited nucleation in an unequilibrated liquid. Below this crossover temperature, the nucleation rate is still predicted when MC simulations are used to directly calculate quantities required by CNT. Discrepancy in critical embryo sizes obtained from MD and MC arises when twinned structures with five-fold symmetry provide a competing free energy pathway out of the critical region. We find that crystallization begins with hcp-fcc stacked precritical nuclei and differentiation to various end structures occurs when these embryos become critical. We confirm that using the largest embryo in the system as a reaction coordinate is useful in determining the onset of growth-limited nucleation and show that it gives the same free energy barriers as the full cluster size distribution once the proper reference state is identified. We find that the bulk melting temperature controls the rate, even though the solid-liquid coexistence temperature for the droplet is significantly lower. The value of surface tension that renders close agreement between CNT and direct rate determination is significantly lower than what is expected for the bulk system.

  2. A mechanism for supercooling in organic liquids

    SciTech Connect

    Thoma, P.E.

    1996-12-31

    In this investigation, a mechanism for supercooling inorganic liquids is formulated. By comparing the melting temperature and spontaneous freezing temperature of the chemicals evaluated with their molecular characteristics, the factors promoting supercooling are developed. The results obtained indicate that the following molecular characteristics promote supercooling in organic liquids: an unequal sharing of electrons between the atoms of a molecule; a three-dimensional chemical structure; a permanent, three-dimensional, and partially charged pocket within the chemical structure; a partially charged projection having a charge opposite that of the pocket and located on the side of the molecule opposite that of the pocket.

  3. Weak Deeply Virtual Compton Scattering

    SciTech Connect

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2007-03-01

    We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

  4. Self-confined dynamics in supercooled liquids during crystallization

    NASA Astrophysics Data System (ADS)

    Sanz, Alejandro; Niss, Kristine; Ezquerra, Tiberio A.; Nogales, Aurora; Jimenez, Monica; Puente-Orench, Ines

    2015-03-01

    Within the temperature window limited by the equilibrium melting temperature and the liquid to glass transition temperature, some glass forming systems tend to undergo crystallization. Unlike polymeric materials, low molecular weight liquids are able to self-organize forming fully crystalline structures, in which the dynamics of the remaining disordered regions may be examined along the whole range of crystalline volume fraction when real time studies are assessed. From the point of view of the molecular mobility, dielectric spectroscopy is a unique tool for unraveling the dynamic effects during crystallization. The aim of this contribution is to show a complete picture of the crystallization process in paradigmatic glass formers like 2-propanol, ethanol and glycerol. The interrelationships between structure and dynamics during crystallization will be discussed, paying special attention to the role played by the hydrogen-bonded network across the phase transformation. Novel results on crystallization of 2-propanol studied by real time quasielastic neutron scattering measurements will also be presented.

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

    NASA Astrophysics Data System (ADS)

    Rustan, Gustav Errol

    been carried out to study the metastable phase formation in an Fe83B17 near eutectic alloy. Initial supercooling measurements using the ISU-ESL identified the formation of three metastable phases: a precipitate phase that shows stable coexistence with the deeply supercooled liquid, and two distinct bulk solidification phases. To identify the structure of the metastable phases, the Washington University Beamline ESL (WU-BESL) has been used to perform in-situ high energy x-ray diffraction measurements of the metastable phases. Based on the x-ray results, the precipitate phase has been identified as bcc-Fe, and the more commonly occurring bulk solidification product has been found to be a two-phase mixture of Fe23B6 plus fcc-Fe, which appears, upon cooling, to transform into a three phase mixture of Fe23B6, bcc-Fe, and an as-yet unidentified phase, with the transformation occurring at approximately the expected fcc-to-bcc transformation temperature of pure Fe. To further characterize the multi-phase metastable alloy, the ISU-ESL has been used to perform measurements of volume thermal expansion via the videographic technique, as well as RF susceptibility via the TDO technique. The results of the thermal expansion and susceptibility data have been found to be sensitive indicators of additional structural changes that may be occurring in the metastable solid at temperatures below 1000 K, and the susceptibility data has revealed that three distinct ferromagnetic phase transitions take place within the multi-phase mixture. Based on these results, it has been hypothesized that there may be an additional transformation taking place that leads to the formation of either bct- or o-Fe3B in addition to the Fe23B6 phase, although further work is required to test this hypothesis.

  6. Two distinct crystallization processes in supercooled liquid

    NASA Astrophysics Data System (ADS)

    Tane, Masakazu; Kimizuka, Hajime; Ichitsubo, Tetsu

    2016-05-01

    Using molecular dynamics simulations we show that two distinct crystallization processes, depending on the temperature at which crystallization occurs, appear in a supercooled liquid. As a model for glass-forming materials, an Al2O3 model system, in which both the glass transition and crystallization from the supercooled liquid can be well reproduced, is employed. Simulations in the framework of an isothermal-isobaric ensemble indicate that the calculated time-temperature-transformation curve for the crystallization to γ(defect spinel)-Al2O3 exhibited a typical nose shape, as experimentally observed in various glass materials. During annealing above the nose temperature, the structure of the supercooled liquid does not change before the crystallization, because of the high atomic mobility (material transport). Thus, the crystallization is governed by the abrupt crystal nucleation, which results in the formation of a stable crystal structure. In contrast, during annealing below the nose temperature, the structure of the supercooled liquid gradually changes before the crystallization, and the formed crystal structure is less stable than that formed above the nose temperature, because of the restricted material transport.

  7. Two distinct crystallization processes in supercooled liquid.

    PubMed

    Tane, Masakazu; Kimizuka, Hajime; Ichitsubo, Tetsu

    2016-05-21

    Using molecular dynamics simulations we show that two distinct crystallization processes, depending on the temperature at which crystallization occurs, appear in a supercooled liquid. As a model for glass-forming materials, an Al2O3 model system, in which both the glass transition and crystallization from the supercooled liquid can be well reproduced, is employed. Simulations in the framework of an isothermal-isobaric ensemble indicate that the calculated time-temperature-transformation curve for the crystallization to γ(defect spinel)-Al2O3 exhibited a typical nose shape, as experimentally observed in various glass materials. During annealing above the nose temperature, the structure of the supercooled liquid does not change before the crystallization, because of the high atomic mobility (material transport). Thus, the crystallization is governed by the abrupt crystal nucleation, which results in the formation of a stable crystal structure. In contrast, during annealing below the nose temperature, the structure of the supercooled liquid gradually changes before the crystallization, and the formed crystal structure is less stable than that formed above the nose temperature, because of the restricted material transport. PMID:27208956

  8. A study of the occurrence of supercooling of water

    NASA Astrophysics Data System (ADS)

    Tan, Kah-Chye; Ho, Wenxian; Katz, J. I.; Feng, Shi-Jiang

    2016-04-01

    Supercooling of water can be easily studied with a simple apparatus suitable for the student laboratory. We describe such an apparatus and its capabilities. The parameters influencing supercooling include the initial water temperature, as well as the type and temperature of the chilling medium. We correlate the occurrence of supercooling with the ability of the chilling medium to promptly nucleate ice; if it nucleates promptly, the layer of ice crystals formed on the boundary will initiate freezing of the bulk water without supercooling. If the chilling medium is unable to nucleate ice promptly, ice nucleation is delayed and the water supercools. Students can study and compare supercooling of distilled and natural water. Even quite dirty river water may be supercooled by as much as 5 °C.

  9. Interface structure at large supercooling

    NASA Astrophysics Data System (ADS)

    Misbah, C.; Müller-Krumbhaar, H.; Temkin, D. E.

    1991-04-01

    The front dynamics during the growth of a pure substance in the large undercooling limit including interface kinetics is analyzed. There exists a critical dimensionless undercooling Δ_s(>1) above which a planar front is linearly stable. For Δ < Δ_s the planar front is unstable against short wavenumbers k's perturbations, 0supercooling regime. They should therefore constitute good candidates on which to perform experiments in this regime where a rich dynamics, including order, temporal chaos, and turbulence..., is expected. Nous étudions la dynamique du front de croissance d'un corps pur en présense de cinétique d'interface non instantanée dans la limite de grandes surfusions. Le front plan est trouvé être stable au dessus d'une surfusion critique Δ_s(>1). Pour le front est instable vis-à-vis des perturbations de petit vecteur d'onde, 0

  10. ARPES investigation of deeply underdoped BISCO 2212

    NASA Astrophysics Data System (ADS)

    Tanaka, K.; Lee, W. S.; Lu, D. H.; Fujii, T.; Fujimori, A.; Hussain, Z.; Shen, Z. X.

    2006-03-01

    We present ARPES results from deeply underdoped BISCO 2212 with Tc ranging from 30 to 50 K. The improved sample quality with Y subsitution enables the detection of much sharper spectral features. We uncovered experimental evidence for two distinct energy gaps in these deeply underdoped samples. The theoretical implications of these findings will de discussed in conjunction with ARPES and RAMAN data.

  11. Surface Crystallization of Supercooled Water in Clouds

    NASA Technical Reports Server (NTRS)

    Tabazadeh, Azadeh; Gore, Warren J. (Technical Monitor)

    2002-01-01

    The process by which liquid cloud droplets homogeneously crystallize into ice is still not well-understood. The ice nucleation process based on the standard and classical theory of homogeneous freezing, initiates within the interior volume of a cloud droplet. Current experimental data on homogeneous freezing rates of ice in droplets of supercooled water, both in air and emulsion oil samples, show considerable scatter. For example, at -33 C, the reported volume-based freezing rates of ice in supercooled water vary by as much as 5 orders of magnitude, which is well outside the range of measurement uncertainties. Here, we show that the process of ice nucleus formation at the air (or oil)-liquid water interface may help to explain why experimental results on ice nucleation rates yield different results in different ambient phases. Our results also suggest that surface crystallization of ice in cloud droplets can explain why low amounts of supercooled water have been observed in the atmosphere near -40 C.

  12. Surface crystallization of supercooled water in clouds

    PubMed Central

    Tabazadeh, A.; Djikaev, Y. S.; Reiss, H.

    2002-01-01

    The process by which liquid cloud droplets homogeneously crystallize into ice is still not well understood. The ice nucleation process based on the standard and classical theory of homogeneous freezing initiates within the interior volume of a cloud droplet. Current experimental data on homogeneous freezing rates of ice in droplets of supercooled water, both in air and emulsion oil samples, show considerable scatter. For example, at −33°C, the reported volume-based freezing rates of ice in supercooled water vary by as many as 5 orders of magnitude, which is well outside the range of measurement uncertainties. Here, we show that the process of ice nucleus formation at the air (or oil)-liquid water interface may help to explain why experimental results on ice nucleation rates yield different results in different ambient phases. Our results also suggest that surface crystallization of ice in cloud droplets can explain why low amounts of supercooled water have been observed in the atmosphere near −40°C. PMID:12456877

  13. Ice growth in supercooled solutions of antifreeze glycoproteins

    NASA Technical Reports Server (NTRS)

    Harrison, K.; Hallett, J.; Burcham, T. S.; Feeney, R. E.; Kerr, W. L.

    1987-01-01

    The effects of different degrees of supercooling on the habit and rates of growth of ice crystals from solutions of antifreeze glycoproteins are reported. To isolate the influence of different solutions and supercooling alone, a system was devised that nucleated crystals in the middle of a uniformly supercooled sample. Alternatively, single crystals of selected orientation were inserted into free liquid surface. A crystallization rate up to five times greater than that in pure water was found. A mechanism explaining these results is suggested.

  14. Stabilization of supercooled fluids by thermal hysteresis proteins.

    PubMed Central

    Wilson, P W; Leader, J P

    1995-01-01

    It has been reported that thermal hysteresis proteins found in many cold-hardy, freeze-avoiding arthropods stabilize their supercooled body fluids. We give evidence that fish antifreeze proteins, which also produce thermal hysteresis, bind to and reduce the efficiency of heterogenous nucleation sites, rather than binding to embryonic ice nuclei. We discuss both possible mechanisms for stabilization of supercooled body fluids and also describe a new method for measuring and defining the supercooling point of small volumes of liquid. PMID:7612853

  15. Dynamics of supercooled water in a biological model system of the amino acid L-lysine.

    PubMed

    Cerveny, Silvina; Swenson, Jan

    2014-10-28

    The dynamics of supercooled water in aqueous solutions of the single amino acid L-lysine has been studied by broadband dielectric spectroscopy. The chosen biological system is unique in the sense that the water content is high enough to fully dissolve the amino acid, but low enough to avoid crystallisation to ice at any temperature. This is not possible to achieve for proteins or other larger biomolecules, where either hydrated samples without ice or solutions with large quantities of ice, or a cryoprotectant sugar, have to be studied at low temperatures. Thus, it is a key finding to be able to study water and biomolecular dynamics in a non-crystallized and biologically realistic solution at supercooled temperatures. Here, we focus on the water dynamics in this unique biological solution of L-lysine and water. We show that this unique system also gives rise to unique water dynamics, since, for the first time, a continuation of a cooperative (α-like) water relaxation is observed after a crossover to a more local β-like water relaxation has occurred with decreasing temperature. This implies that the supercooled water in the biological solution shows a twofold relaxation behaviour, with one relaxation identical to the main relaxation of water in hard confinements and one relaxation almost identical to the main water relaxation in ordinary aqueous solutions. PMID:25224819

  16. Computing the viscosity of supercooled liquids: Markov Network model.

    PubMed

    Li, Ju; Kushima, Akihiro; Eapen, Jacob; Lin, Xi; Qian, Xiaofeng; Mauro, John C; Diep, Phong; Yip, Sidney

    2011-01-01

    The microscopic origin of glass transition, when liquid viscosity changes continuously by more than ten orders of magnitude, is challenging to explain from first principles. Here we describe the detailed derivation and implementation of a Markovian Network model to calculate the shear viscosity of deeply supercooled liquids based on numerical sampling of an atomistic energy landscape, which sheds some light on this transition. Shear stress relaxation is calculated from a master-equation description in which the system follows a transition-state pathway trajectory of hopping among local energy minima separated by activation barriers, which is in turn sampled by a metadynamics-based algorithm. Quantitative connection is established between the temperature variation of the calculated viscosity and the underlying potential energy and inherent stress landscape, showing a different landscape topography or "terrain" is needed for low-temperature viscosity (of order 10(7) Pa·s) from that associated with high-temperature viscosity (10(-5) Pa·s). Within this range our results clearly indicate the crossover from an essentially Arrhenius scaling behavior at high temperatures to a low-temperature behavior that is clearly super-Arrhenius (fragile) for a Kob-Andersen model of binary liquid. Experimentally the manifestation of this crossover in atomic dynamics continues to raise questions concerning its fundamental origin. In this context this work explicitly demonstrates that a temperature-dependent "terrain" characterizing different parts of the same potential energy surface is sufficient to explain the signature behavior of vitrification, at the same time the notion of a temperature-dependent effective activation barrier is quantified. PMID:21464988

  17. Fluctuations and local ice structure in model supercooled water

    NASA Astrophysics Data System (ADS)

    Overduin, S. D.; Patey, G. N.

    2015-09-01

    Large-scale simulations (up to 32 000 molecules) are used to analyze local structures and fluctuations for the TIP4P/2005 and TIP5P water models, under deeply supercooled conditions, near previously proposed liquid-liquid critical points. Bulk freezing does not occur in our simulations, but correlations between molecules with local ice-like structure (ice-like molecules) are strong and long ranged (˜4 nm), exceeding the shortest dimension of smaller simulation cells at the lowest temperatures considered. Correlations between ice-like molecules decay slowly at low temperature, on the order of a hundred nanoseconds. Local ice-like structure is strongly correlated with highly tetrahedral liquid structure at all times, both structures contribute to density fluctuations, and to the associated anomalous scattering. For the TIP4P/2005 and TIP5P models, we show that the apparent spontaneous liquid-liquid phase separations, recently reported [T. Yagasaki, M. Matsumoto, and H. Tanaka, Phys. Rev. E 89, 020301 (2014)] for small rectangular simulation cells below the proposed critical points, exhibit strong system size dependence and do not occur at all in the largest systems we consider. Furthermore, in the smaller rectangular systems where layers of different densities do occur, we find that the appearance of a region of low density is always accompanied simultaneously by an excess of local ice density, with no separation in time. Our results suggest that the density differences observed in direct simulations for the two models considered here are likely due to long-range correlations between ice-like molecules and do not provide strong evidence of liquid-liquid phase separation.

  18. PREFACE: Water in confined geometries

    NASA Astrophysics Data System (ADS)

    Rovere, Mauro

    2004-11-01

    The study of water confined in complex systems in solid or gel phases and/or in contact with macromolecules is relevant to many important processes ranging from industrial applications such as catalysis and soil chemistry, to biological processes such as protein folding or ionic transport in membranes. Thermodynamics, phase behaviour and the molecular mobility of water have been observed to change upon confinement depending on the properties of the substrate. In particular, polar substrates perturb the hydrogen bond network of water, inducing large changes in the properties upon freezing. Understanding how the connected random hydrogen bond network of bulk water is modified when water is confined in small cavities inside a substrate material is very important for studies of stability and the enzymatic activity of proteins, oil recovery or heterogeneous catalysis, where water-substrate interactions play a fundamental role. The modifications of the short-range order in the liquid depend on the nature of the water-substrate interaction, hydrophilic or hydrophobic, as well as on its spatial range and on the geometry of the substrate. Despite extensive study, both experimentally and by computer simulation, there remain a number of open problems. In the many experimental studies of confined water, those performed on water in Vycor are of particular interest for computer simulation and theoretical studies since Vycor is a porous silica glass characterized by a quite sharp distribution of pore sizes and a strong capability to absorb water. It can be considered as a good candidate for studying the general behaviour of water in hydrophilic nanopores. But there there have been a number of studies of water confined in more complex substrates, where the interpretation of experiments and computer simulation is more difficult, such as in zeolites or in aerogels or in contact with membranes. Of the many problems to consider we can mention the study of supercooled water. It is

  19. Revisiting the glass transition and dynamics of supercooled benzene by calorimetric studies

    NASA Astrophysics Data System (ADS)

    Tu, Wenkang; Chen, Zeming; Li, Xiangqian; Gao, Yanqin; Liu, Riping; Wang, Li-Min

    2015-10-01

    The glass transition and dynamics of benzene are studied in binary mixtures of benzene with five glass forming liquids, which can be divided into three groups: (a) o-terphenyl and m-xylene, (b) N-butyl methacrylate, and (c) N,N-dimethylpropionamide and N,N-diethylformamide to represent the weak, moderate, and strong interactions with benzene. The enthalpies of mixing, ΔHmix, for the benzene mixtures are measured to show positive or negative signs, with which the validity of the extrapolations of the glass transition temperature Tg to the benzene-rich regions is examined. The extrapolations for the Tg data in the mixtures are found to converge around the point of 142 K, producing Tg of pure benzene. The fragility m of benzene is also evaluated by extrapolating the results of the mixtures, and a fragility m ˜ 80 is yielded. The obtained Tg and m values for benzene allow for the construction of the activation plot in the deeply supercooled region. The poor glass formability of benzene is found to result from the high melting point, which in turn leads to low viscosity in the supercooled liquid.

  20. Boundaries Matter for Confined Colloidal Glasses

    NASA Astrophysics Data System (ADS)

    Hunter, Gary L.; Edmond, Kazem V.; Weeks, Eric R.

    2012-02-01

    We confine dense colloidal suspensions within emulsion droplets to examine how confinement and properties of the confining medium affect the colloidal glass transition. Samples are imaged via fast confocal microscopy. By observing a wide range of droplet sizes and varying the viscosity of the external continuous phase, we separate finite size and boundary effects on particle motions within the droplet. Suspensions are composed of binary PMMA spheres in organic solvents while the external phases are simple mixtures of water and glycerol. In analogy with molecular super-cooled liquids and thin-film polymers, we find that confinement effects in colloidal systems are not merely functions of the finite size of the system, but are strongly dependent on the viscosity of the confining medium and interactions between particles and the interface of the two phases.

  1. A Molecular Dynamics Study of the Structure-Dynamics Relationships of Supercooled Liquids and Glasses

    NASA Astrophysics Data System (ADS)

    Soklaski, Ryan

    of the Stokes-Einstein relationship, the decoupling of particle diffusivities, and the development of general "glassy" relaxation features are found to coincide with successive manifestation of icosahedral ordering that arise as the liquid is supercooled. Remarkably, we detect critical-like features in the growth of the icosahedron network, with signatures that suggest that a liquid-liquid phase transition may occur in the deeply supercooled regime to precede glass formation. Such a transition is predicted to occur in many supercooled liquids, although explicit evidence of this phenomenon in realistic systems is scarce. Ultimately this work concludes that icosahedral order characterizes all dynamical regimes of Cu64Zr 36, demonstrating the importance and utility of studying supercooled liquids in the context of locally-preferred structure. More broadly, it serves to confirm and inform recent theoretical and empirical findings that are central to understanding the physics underlying the glass transition.

  2. Heat of freezing for supercooled water: measurements at atmospheric pressure.

    PubMed

    Cantrell, Will; Kostinski, Alexander; Szedlak, Anthony; Johnson, Alexandria

    2011-06-16

    Unlike reversible phase transitions, the amount of heat released upon freezing of a metastable supercooled liquid depends on the degree of supercooling. Although terrestrial supercooled water is ubiquitous and has implications for cloud dynamics and nucleation, measurements of its heat of freezing are scarce. We have performed calorimetric measurements of the heat released by freezing water at atmospheric pressure as a function of supercooling. Our measurements show that the heat of freezing can be considerably below one predicted from a reversible hydrostatic process. Our measurements also indicate that the state of the resulting ice is not fully specified by the final pressure and temperature; the ice is likely to be strained on a variety of scales, implying a higher vapor pressure. This would reduce the vapor gradient between supercooled water and ice in mixed phase atmospheric clouds. PMID:21087023

  3. Deeply virtual Compton scattering from gauge/gravity duality

    SciTech Connect

    Costa, Miguel S.; Djuric, Marko

    2013-04-15

    We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well.

  4. Analysis of supercooling activities of surfactants.

    PubMed

    Kuwabara, Chikako; Terauchi, Ryuji; Tochigi, Hiroshi; Takaoka, Hisao; Arakawa, Keita; Fujikawa, Seizo

    2014-08-01

    Supercooling-promoting activities (SCAs) of 25 kinds of surfactants including non-ionic, anionic, cationic and amphoteric types were examined in solutions (buffered Milli-Q water, BMQW) containing the ice nucleation bacterium (INB) Erwinia ananas, silver iodide (AgI) or BMQW alone, which unintentionally contained unidentified ice nucleators, by a droplet freezing assay. Most of the surfactants exhibited SCA in solutions containing AgI but not in solutions containing the INB E. ananas or BMQW alone. SCAs of many surfactants in solutions containing AgI were very high compared with those of previously reported supercooling-promoting substances. Cationic surfactants, hexadecyltrimethylammonium bromide (C16TAB) and hexadecyltrimethylammonium chloride (C16TAC), at concentrations of 0.01% (w/v) exhibited SCA of 11.8 °C, which is the highest SCA so far reported. These surfactants also showed high SCAs at very low concentrations in solutions containing AgI. C16TAB exhibited SCA of 5.7 °C at a concentration of 0.0005% (w/v). PMID:24792543

  5. Anomalous Wien Effects in Supercooled Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Patro, L. N.; Burghaus, O.; Roling, B.

    2016-05-01

    We have measured conductivity spectra of several supercooled monocationic and dicationic ionic liquids in the nonlinear regime by applying ac electric fields with large amplitudes up to about 180 kV /cm . Thereby, higher harmonic ac currents up to the 7th order were detected. Our results point to the existence of anomalous Wien effects in supercooled ionic liquids. Most ionic liquids studied here exhibit a conductivity-viscosity relation, which is close to the predictions of the Nernst-Einstein and Stokes-Einstein equations, as observed for classical strong electrolytes like KCl. These "strong" ionic liquids show a much stronger nonlinearity of the conductivity than classical strong electrolytes. On the other hand, the conductivity-viscosity relation of the ionic liquid [P6 ,6 ,6 ,14][Cl ] points to ion association effects. This "weak" ionic liquid shows a strength of the nonlinear effect, which is comparable to classical weak electrolytes. However, the nonlinearity increases quadratically with the field. We suggest that a theory for explaining these anomalies will have to go beyond the level of Coulomb lattice gas models.

  6. Analysis & Simulation of Dynamics in Supercooled Liquids

    NASA Astrophysics Data System (ADS)

    Elmatad, Yael Sarah

    2011-12-01

    The nature of supercooled liquids and the glass transition has been debated by many scientists. Several theories have been put forth to describe the remarkable properties of this out-of-equilibrium material. Each of these theories makes specific predictions as to how the scaling of various transport properties in supercooled materials should behave. Given access to a large pool of high-quality supercooled liquid data we seek to compare these theories to one another. Moreover, we explore properties of a pair of models which are the basis for one particularly attractive theory---Chandler-Garrahan theory---and discuss the models' behavior in space-time and possible implications to the behavior of experimental supercooled liquids. Here we investigate the nature of dynamics in supercooled liquids using a two pronged approach. First we analyze the transport properties found in experiments and simulations of supercooled liquids. Then, we analyze simulation trajectories for lattice models which reproduce many of the interesting properties of supercooled liquids. In doing so, we illuminate several glass universalities, common properties of a wide variety of glass formers. By analyzing relaxation time and viscosity data for over 50 data sets and 1200 points, we find that relaxation time can be collapsed onto a single, parabolic curve. This collapse supports a theory of universal glass behavior based on facilitated models proposed by David Chandler and Juan Garrahan in 2003. We then show that the parabolic fit parameters for any particular liquid are a material property: they converge fast and are capable of predicting behavior in regions beyond the included data sets. We compare this property to other popular fitting schemes such as the Vogel-Fulcher, double exponential, and fractional exponential forms and conclude that these three forms result in parameters which are non predictive and therefore not material properties. Additionally, we examine the role of attractive

  7. Vapor Condensed and Supercooled Glassy Nanoclusters.

    PubMed

    Qi, Weikai; Bowles, Richard K

    2016-03-22

    We use molecular simulation to study the structural and dynamic properties of glassy nanoclusters formed both through the direct condensation of the vapor below the glass transition temperature, without the presence of a substrate, and via the slow supercooling of unsupported liquid nanodroplets. An analysis of local structure using Voronoi polyhedra shows that the energetic stability of the clusters is characterized by a large, increasing fraction of bicapped square antiprism motifs. We also show that nanoclusters with similar inherent structure energies are structurally similar, independent of their history, which suggests the supercooled clusters access the same low energy regions of the potential energy landscape as the vapor condensed clusters despite their different methods of formation. By measuring the intermediate scattering function at different radii from the cluster center, we find that the relaxation dynamics of the clusters are inhomogeneous, with the core becoming glassy above the glass transition temperature while the surface remains mobile at low temperatures. This helps the clusters sample the highly stable, low energy structures on the potential energy surface. Our work suggests the nanocluster systems are structurally more stable than the ultrastable glassy thin films, formed through vapor deposition onto a cold substrate, but the nanoclusters do not exhibit the superheating effects characteristic of the ultrastable glass states. PMID:26866858

  8. Anomalous Wien Effects in Supercooled Ionic Liquids.

    PubMed

    Patro, L N; Burghaus, O; Roling, B

    2016-05-01

    We have measured conductivity spectra of several supercooled monocationic and dicationic ionic liquids in the nonlinear regime by applying ac electric fields with large amplitudes up to about 180  kV/cm. Thereby, higher harmonic ac currents up to the 7th order were detected. Our results point to the existence of anomalous Wien effects in supercooled ionic liquids. Most ionic liquids studied here exhibit a conductivity-viscosity relation, which is close to the predictions of the Nernst-Einstein and Stokes-Einstein equations, as observed for classical strong electrolytes like KCl. These "strong" ionic liquids show a much stronger nonlinearity of the conductivity than classical strong electrolytes. On the other hand, the conductivity-viscosity relation of the ionic liquid [P_{6,6,6,14}][Cl] points to ion association effects. This "weak" ionic liquid shows a strength of the nonlinear effect, which is comparable to classical weak electrolytes. However, the nonlinearity increases quadratically with the field. We suggest that a theory for explaining these anomalies will have to go beyond the level of Coulomb lattice gas models. PMID:27203333

  9. Deeply Virtual Pseudoscalar Meson Production with CLAS

    SciTech Connect

    Valery Kubarovsky; Paul Stoler; Ivan Bedlinsky

    2007-09-03

    Deeply virtual Compton scattering, cross sections and asymmetries for the pi^0 and eta exclusive electroproduction in a very wide kinematic range of Q^2, t and x_B have been measured with CLAS (Jlab). Initial analyzes already are showing remarkable results. These data will help us to better understand the transition from soft to hard mechanisms.

  10. Study on Supercooling Release in Encapsulated Ice System

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Yooko; Hasegawa, Hiromi; Sasaki, Kazuhiro; Kurosaki, Kenji; Sato, Mamoru; Watanabe, Kenji; Iwatsubo, Tetsushiro

    As regards the supercooling phenomena which is important matter in encapsulated ice system, we studied the supercooling release agent using the microorganism. Though the nucleation active bacteria had the high super cooling release ability, it was proved that the performance gradually lowered in long terms continuous use, when the live microorganism was used. In order to solve this problem, the sterilization treatment of the microorganism was examined and it was clariiied that there was the high effect in the ultraviolet irradiation. In addition, the persistence of the supercooling release ability is improved by freeze-drying treatment.

  11. Reproducing Black's experiments: freezing point depression and supercooling of water

    NASA Astrophysics Data System (ADS)

    Güémez, J.; Fiolhais, C.; Fiolhais, M.

    2002-01-01

    We carried out two historical experiments referred to by Joseph Black, one on freezing mixtures of salted water with ice and another on freezing supercooled pure water by a small disturbance. The results confirm thermodynamical predictions for the depression of the freezing point of salted water and for the latent heat of freezing of supercooled water respectively, which came after Black. The depression of the freezing point can hardly be fitted in the framework of the caloric theory of heat, which was taken for granted by Black, and the instantaneous freezing of supercooled water also poses some difficulties for that theory.

  12. Supercooling effects in faceted eutectic Nb-Si alloys

    NASA Technical Reports Server (NTRS)

    Gokhale, A. B.; Sarkar, G.; Abbaschian, G. J.; Haygarth, J. C.; Wojcik, C.

    1988-01-01

    The effect of melt supercooling on the microstructure of an Nb-58 at. pct Si alloy is investigated experimentally using an electromagnetic levitation apparatus. It is found that, starting with an alloy nominally of eutectic composition, nucleation of Nb5Si3 occurs in the supercooled liquid first. Upon further cooling, the remaining liquid continues to supercool until the second phase, NbSi2 is nucleated, which is commonly accompanied by rapid recalescence. The primary phase exibits a eutectoid-type decomposition. The observations are discussed with reference to the results of quantitative microstructural measurements, compositional and thermal analysis, and preliminary thermodynamic modeling of the phase diagram.

  13. Some fundamental aspects of solidification in a supercooled melt

    NASA Technical Reports Server (NTRS)

    Laxmanan, V.

    1983-01-01

    A model of dendritic growth in both supercooled pure and alloy melts is presented. In a pure melt, dendrite morphology is determined by the value of the dimensionless parameter sigma = 2 alpha (L)d(o)/sq Rr(t) whereas, in an alloy melt it is determined by the parameter sigma = 2 lambda (c)D(L)/sq Rr(t). The application of the above analysis to cylindrical and spherical growth morphologies obtained in highly supercooled melts has been discussed. An upper and lower bound for the particle or tip radius in this case has been obtained in terms of the growth rate and the initial bath supercooling.

  14. Microscopic dynamics of supercooled low weight alcohols

    NASA Astrophysics Data System (ADS)

    Palomar, Ricardo; Sesé, Gemma

    2010-07-01

    Dynamical properties of low weight alcohols have been analyzed both in the liquid and the supercooled states. Realistic interatomic potential models for methanol and ethanol have been used. The influence of temperature on the hydrogen-bonded structure has been undertaken. Remarkable similarities have been obtained in both systems. Velocity autocorrelation functions have been evaluated for molecules participating in zero, one, and two hydrogen bonds at a wide range of temperatures. A backscattering area preceded by a shoulder has been identified as a signature of this function when evaluated for the subset of molecules that participate in two hydrogen bonds. Memory functions have also been evaluated. Their initial decay depends only slightly upon temperature. A more marked temperature dependence is observed for the nonassociated molecules. For them, reasonable agreement with the mode-coupling approach predictions has been encountered.

  15. Bulk Metallic Glass in Supercooled Liquid State

    NASA Astrophysics Data System (ADS)

    Wang, X. Y.; Deng, L.; Tang, N.; Jin, J. S.

    2014-07-01

    Size effect on the flow behavior of Zr55Al10Ni5Cu30 bulk metallic glass in its supercooled liquid state was investigated by compression tests with specimen diameters varying from 1 to 3 mm. It was found that the smaller the specimen, the higher flow stress exhibits. Strain gradient theory considering friction effect is validated to be suitable to rationalize this size effect. The more geometrical-necessary flow sites needed to be created in smaller specimens, the higher stress it may result in. Considering the efficiency of power dissipation and instability condition, processing maps of different specimens were constructed. With the specimen size decreasing, the processing condition corresponding to low temperature or high strain rate becomes disadvantageous to the thermoplastic forming of Zr55Al10Ni5Cu30, which is closely related to the local stress concentration and strain gradient induced by friction.

  16. Ergodicity and slow diffusion in a supercooled liquid

    NASA Astrophysics Data System (ADS)

    Bidhoodi, Neeta; Das, Shankar P.

    2016-05-01

    A model for the slow dynamics of the supercooled liquid is formulated in terms of the standard equations of fluctuating nonlinear hydrodynamics (FNH) with the inclusion of an extra diffusive mode for the collective density fluctuations. If the compressible nature of the liquid is completely ignored, this diffusive mode sets the longest relaxation times in the supercooled state and smooths off a possible sharp ergodicity-nonergodicity (ENE) transition predicted in a mode coupling theory. The scenario changes when the complete dynamics is considered with the inclusion of 1 / ρ nonlinearities in the FNH equations, reflecting the compressible nature of the liquid. The latter primarily determines the extent of slowing down in the supercooled liquid. The presence of slow diffusive modes in the supercooled liquid do not give rise to very long relaxation times unless the role of couplings between density and currents in the compressible liquid is negligible.

  17. Compound chondrule formation via collision of supercooled droplets

    NASA Astrophysics Data System (ADS)

    Arakawa, Sota; Nakamoto, Taishi

    2016-09-01

    We present a novel model showing that compound chondrules are formed by collisions of supercooled droplets. This model reproduces two prominent observed features of compound chondrules: the nonporphyritic texture and the size ratio between two components.

  18. Crystallization in supercooled liquid Cu: Homogeneous nucleation and growth

    SciTech Connect

    E, J. C.; Wang, L.; Luo, S. N.; Cai, Y.; Wu, H. A.

    2015-02-14

    Homogeneous nucleation and growth during crystallization of supercooled liquid Cu are investigated with molecular dynamics simulations, and the microstructure is characterized with one- and two-dimensional x-ray diffraction. The resulting solids are single-crystal or nanocrystalline, containing various defects such as stacking faults, twins, fivefold twins, and grain boundaries; the microstructure is subject to thermal fluctuations and extent of supercooling. Fivefold twins form via sequential twinning from the solid-liquid interfaces. Critical nucleus size and nucleation rate at 31% supercooling are obtained from statistical runs with the mean first-passage time and survival probability methods, and are about 14 atoms and 10{sup 32} m{sup −3}s{sup −1}, respectively. The bulk growth dynamics are analyzed with the Johnson-Mehl-Avrami law and manifest three stages; the Avrami exponent varies in the range of 1–19, which also depends on thermal fluctuations and supercooling.

  19. Crystallization in supercooled liquid Cu: Homogeneous nucleation and growth.

    PubMed

    E, J C; Wang, L; Cai, Y; Wu, H A; Luo, S N

    2015-02-14

    Homogeneous nucleation and growth during crystallization of supercooled liquid Cu are investigated with molecular dynamics simulations, and the microstructure is characterized with one- and two-dimensional x-ray diffraction. The resulting solids are single-crystal or nanocrystalline, containing various defects such as stacking faults, twins, fivefold twins, and grain boundaries; the microstructure is subject to thermal fluctuations and extent of supercooling. Fivefold twins form via sequential twinning from the solid-liquid interfaces. Critical nucleus size and nucleation rate at 31% supercooling are obtained from statistical runs with the mean first-passage time and survival probability methods, and are about 14 atoms and 10(32) m(-3)s(-1), respectively. The bulk growth dynamics are analyzed with the Johnson-Mehl-Avrami law and manifest three stages; the Avrami exponent varies in the range of 1-19, which also depends on thermal fluctuations and supercooling. PMID:25681932

  20. Crystallization in supercooled liquid Cu: Homogeneous nucleation and growth

    NASA Astrophysics Data System (ADS)

    E, J. C.; Wang, L.; Cai, Y.; Wu, H. A.; Luo, S. N.

    2015-02-01

    Homogeneous nucleation and growth during crystallization of supercooled liquid Cu are investigated with molecular dynamics simulations, and the microstructure is characterized with one- and two-dimensional x-ray diffraction. The resulting solids are single-crystal or nanocrystalline, containing various defects such as stacking faults, twins, fivefold twins, and grain boundaries; the microstructure is subject to thermal fluctuations and extent of supercooling. Fivefold twins form via sequential twinning from the solid-liquid interfaces. Critical nucleus size and nucleation rate at 31% supercooling are obtained from statistical runs with the mean first-passage time and survival probability methods, and are about 14 atoms and 1032 m-3s-1, respectively. The bulk growth dynamics are analyzed with the Johnson-Mehl-Avrami law and manifest three stages; the Avrami exponent varies in the range of 1-19, which also depends on thermal fluctuations and supercooling.

  1. An Easy Classroom Experiment on the Supercooling of Water

    ERIC Educational Resources Information Center

    Gianino, Concetto

    2007-01-01

    The change from the state of supercooling to the solid state of ice is called superfreezing. This process is not uncommon and takes place in domestic freezers. It is also easy to reproduce in the laboratory. (Contains 6 figures.)

  2. Deeply Virtual Compton Scattering with CLAS

    SciTech Connect

    F.X. Girod

    2007-12-17

    The beam spin asymmetries of the reaction ep -> epg in the Bjorken regime were measured over a wide kinematical domain using the CLAS detector and a new lead-tungstate calorimeter. Through the interference of the Bethe-Heitler process with Deeply Virtual Compton Scattering, those asymmetries provide constraints for the nucleon Generalized Parton Distributions models. The observed shapes are in agreement with twist-2 dominance predictions.

  3. Sivers effect in semiinclusive deeply inelastic scattering

    SciTech Connect

    Collins, J.C.; Efremov, A. V.; Goeke, K.; Menzel, S.; Metz, A.; Schweitzer, P.

    2006-01-01

    The Sivers function is extracted from HERMES data on single spin asymmetries in semi-inclusive deeply inelastic scattering. Our analysis use a simple Gaussian model for the distribution of transverse parton momenta, together with the flavor dependence given by the leading 1/N{sub c} approximation and a neglect of the Sivers antiquark distribution. We find that within the errors of the data these approximations are sufficient.

  4. Delivery after Operation for Deeply Infiltrating Endometriosis.

    PubMed

    Allerstorfer, Christina; Oppelt, Peter; Enzelsberger, Simon H; Shamiyeh, Andreas; Schimetta, Wolfgang; Shebl, Omar Josef; Mayer, Richard Bernhard

    2016-01-01

    Background. It has been suggested that, during pregnancy, endometriosis can cause a variety of disease-related complications. Objectives. The purpose of the study was to find out if women with histologically confirmed endometriosis do have a higher risk of adverse pregnancy outcome and if they suffer from a higher rate of complications during labor. Study Design. 51 women who underwent surgery because of deeply infiltrating endometriosis in the General Hospital Linz and the Women's General Hospital Linz and who gave birth in the Women's General Hospital Linz after the surgery were included in our survey. Results. 31 women (60.8%) had a spontaneous delivery and in 20 women (39.2%) a caesarean section was performed. There were no cases of third- and fourth-degree perineal lacerations. Collectively there were 4 cases (7.8%) of preterm delivery and one case (2.0%) of premature rupture of membranes. In two women (6.5%) a retained placenta was diagnosed. Conclusions. Our study is the first description on delivery modes after surgery for deeply infiltrating endometriosis. We did not find an elevated risk for perineal or vaginal laceration in women with a history of surgery for deeply infiltrating endometriosis, even when a resection of the rectum or of the posterior vaginal wall had been performed. PMID:27517050

  5. Deeply Virtual Exclusive Reactions with CLAS

    SciTech Connect

    Kubarovsky, Valery

    2011-03-01

    Deeply virtual exclusive reactions offer an unique opportunity to study the structure of the nucleon at the parton level as one has access to Bjorken xB and momentum transfer to the nucleon t at the same time. Such processes can reveal much more information about the structure of the nucleon than either inclusive electroproduction or elastic form factors alone. Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply VirtualMeson Production (DVMP) have been carried out in Hall B at Jefferson Lab. DVCS helicity–dependent and helicity–independent cross sections and beam spin asymmetries have been measured with CLAS, as well as cross sections and asymmetries for the p 0, h, r 0, r+, w and f for exclusive electroproduction. The data were taken in a wide kinematic range in Q2=1–4.5 GeV2, xB=0.1–0.5, and |t| up to 2 GeV2. We will discuss the interpretation of these data in terms of traditional Regge and Generalized Parton Distributions models. We view the work presented in this report as leading into the program of the Jefferson Lab 12 GeV upgrade. The increased energy and luminosity will allow us to acquire data at much higher Q2 and xB, and perform Rosenbluth L/T separations of the cross sections.

  6. Delivery after Operation for Deeply Infiltrating Endometriosis

    PubMed Central

    Allerstorfer, Christina; Enzelsberger, Simon H.; Shebl, Omar Josef; Mayer, Richard Bernhard

    2016-01-01

    Background. It has been suggested that, during pregnancy, endometriosis can cause a variety of disease-related complications. Objectives. The purpose of the study was to find out if women with histologically confirmed endometriosis do have a higher risk of adverse pregnancy outcome and if they suffer from a higher rate of complications during labor. Study Design. 51 women who underwent surgery because of deeply infiltrating endometriosis in the General Hospital Linz and the Women's General Hospital Linz and who gave birth in the Women's General Hospital Linz after the surgery were included in our survey. Results. 31 women (60.8%) had a spontaneous delivery and in 20 women (39.2%) a caesarean section was performed. There were no cases of third- and fourth-degree perineal lacerations. Collectively there were 4 cases (7.8%) of preterm delivery and one case (2.0%) of premature rupture of membranes. In two women (6.5%) a retained placenta was diagnosed. Conclusions. Our study is the first description on delivery modes after surgery for deeply infiltrating endometriosis. We did not find an elevated risk for perineal or vaginal laceration in women with a history of surgery for deeply infiltrating endometriosis, even when a resection of the rectum or of the posterior vaginal wall had been performed. PMID:27517050

  7. Callibration of capillaries for density measurement of supercooled water

    NASA Astrophysics Data System (ADS)

    Peukert, Pavel; Duška, Michal; Hykl, Jiří; Sladký, Petr; Nikl, Zbyněk; Hrubý, Jan

    2015-05-01

    Density of supercooled water at elevated pressure is interesting because of the strong anomalies which can be explained by existence of a liquid-liquid critical point in the region of supercooled water. In order to provide accurate data for density at these conditions a procedure was developed to calibrate the course of the inner cross section of a capillary along its length. Further, the image analysis for the sub-pixel evaluation of meniscus postion is described.

  8. Super-cooled and amorphous lipid-based colloidal dispersions for the delivery of phytosterols.

    PubMed

    Ribeiro, H S; Gupta, R; Smith, K W; van Malssen, K F; Popp, A K; Velikov, K P

    2016-07-01

    Super-cooled and amorphous lipid-based colloids are highly desirable delivery systems because of their ability to encapsulate compounds in a soluble or in a non-crystalline state. In this study, we demonstrate the preparation and characterization of super-cooled and amorphous lipid-based nanoscale colloidal dispersions containing high concentrations of phytosterols (PSs). PSs are highly hydrophobic natural bioactive compounds that are known to significantly reduce blood cholesterol levels in humans, but are insoluble in water and are poorly soluble in common lipids such as triacylglycerols (TAGs). Using the ultrahigh pressure homogenization of pre-heated dispersions, followed by temperature quenching, colloidal dispersions with varying concentrations of PSs in the lipid phase are prepared. Long and medium chain TAGs in combination with a non-ionic surfactant are used. The particle size, morphology and stability are analysed by dynamic and static light scattering, electron microscopy, and X-ray diffraction. Rapid temperature quenching enables the formation of stable colloidal dispersions of 10 wt% PSs, more than five times the equilibrium solubility at room temperature. Super-cooled emulsions are formed using liquid TAG, whereas amorphous particles are formed in the case of solid TAG. In both cases, the complete suppression of the crystallization of both PSs and lipids is observed due to the nanoscale confinement. The colloidal dispersions are stable for at least four months. The insights of this work will help understand the colloid formation and particle morphology control in the development of delivery systems for hydrophobic bio-actives such as drugs, cosmeceuticals, nutraceuticals, nutritional and agricultural nanoscale formulations. PMID:27174457

  9. Deeply Virtual Exclusive Reactions with CLAS

    SciTech Connect

    Valery Kubarovsky

    2011-11-01

    Deeply virtual exclusive reactions offer an unique opportunity to study the structure of the nucleon at the parton level as one has access to Bjorken x{sub B} and momentum transfer to the nucleon t at the same time. Such processes can reveal much more information about the structure of the nucleon than either inclusive electroproduction or elastic form factors alone. Dedicated experiments to study Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) have been carried out in Hall B at Jefferson Lab. DVCS helicity–dependent and helicity–independent cross sections and beam spin asymmetries have been measured with CLAS, as well as cross sections and asymmetries for the {pi}{sup }0, {eta} , {rho}{sup }0, {rho}{sup +}, {omega} and {phi} for exclusive electroproduction. The data were taken in a wide kinematic range in Q{sup 2}=1–4.5 GeV{sup 2}, x{sub B}=0.1–0.5, and {absval t} up to 2 GeV{sup 2}. We will discuss the interpretation of these data in terms of traditional Regge and Generalized Parton Distributions (GPDs) models. The successful description of the recent CLAS pseudoscalar meson exclusive production data by GPD-based model provides a unique opportunity to access the transversity GPDs. We view the work presented in this report as leading into the program of the Jefferson Lab 12 GeV upgrade. The increased energy and luminosity will allow us to acquire data at much higher Q{sup 2} and x{sub B}, and perform Rosenbluth L/T separations of the cross sections.

  10. Frost halos from supercooled water droplets

    PubMed Central

    Jung, Stefan; Tiwari, Manish K.; Poulikakos, Dimos

    2012-01-01

    Water freezing on solid surfaces is ubiquitous in nature. Even though icing/frosting impairs the performance and safety in many processes, its mechanism remains inadequately understood. Changing atmospheric conditions, surface properties, the complexity of icing physics, and the unorthodox behavior of water are the primary factors that make icing and frost formation intriguing and difficult to predict. In addition to its unquestioned scientific and practical importance, unraveling the frosting mechanism under different conditions is a prerequisite to develop “icephobic” surfaces, which may avoid ice formation and contamination. In this work we demonstrate that evaporation from a freezing supercooled sessile droplet, which starts explosively due to the sudden latent heat released upon recalescent freezing, generates a condensation halo around the droplet, which crystallizes and drastically affects the surface behavior. The process involves simultaneous multiple phase transitions and may also spread icing by initiating sequential freezing of neighboring droplets in the form of a domino effect and frost propagation. Experiments under controlled humidity conditions using substrates differing up to three orders of magnitude in thermal conductivity establish that a delicate balance between heat diffusion and vapor transport determines the final expanse of the frozen condensate halo, which, in turn, controls frost formation and propagation. PMID:23012410

  11. Supercooled Large Droplet Icing Flight Research Program

    NASA Technical Reports Server (NTRS)

    Miller, Dean R.

    2000-01-01

    During the past three winters, the NASA Glenn Research Center at Lewis Field conducted icing research flights throughout the Great Lakes region to measure the characteristics of a severe icing condition having Supercooled Large Droplets (SLD). SLD was implicated in the 1994 crash of the ATR-72 commuter aircraft. This accident focused attention on the safety hazard associated with SLD, and it led the Federal Aviation Administration (FAA) to identify the need for a better understanding of the atmospheric characteristics of this icing condition. In response to this need, Glenn developed a cooperative icing flight research program with the FAA, the National Center for Atmospheric Research, and the Atmospheric Environment Service of Canada. The primary objectives were to (1) characterize the SLD icing condition in terms of important icing-related parameters (such as cloud droplet size, cloud water content, and temperature), (2) develop and refine SLD icing weather forecast products, and (3) document and measure the effects of SLD ice accretions on aircraft performance.

  12. Structure of ice crystallized from supercooled water

    PubMed Central

    Malkin, Tamsin L.; Murray, Benjamin J.; Brukhno, Andrey V.; Anwar, Jamshed; Salzmann, Christoph G.

    2012-01-01

    The freezing of water to ice is fundamentally important to fields as diverse as cloud formation to cryopreservation. At ambient conditions, ice is considered to exist in two crystalline forms: stable hexagonal ice and metastable cubic ice. Using X-ray diffraction data and Monte Carlo simulations, we show that ice that crystallizes homogeneously from supercooled water is neither of these phases. The resulting ice is disordered in one dimension and therefore possesses neither cubic nor hexagonal symmetry and is instead composed of randomly stacked layers of cubic and hexagonal sequences. We refer to this ice as stacking-disordered ice I. Stacking disorder and stacking faults have been reported earlier for metastable ice I, but only for ice crystallizing in mesopores and in samples recrystallized from high-pressure ice phases rather than in water droplets. Review of the literature reveals that almost all ice that has been identified as cubic ice in previous diffraction studies and generated in a variety of ways was most likely stacking-disordered ice I with varying degrees of stacking disorder. These findings highlight the need to reevaluate the physical and thermodynamic properties of this metastable ice as a function of the nature and extent of stacking disorder using well-characterized samples. PMID:22232652

  13. Deeply Virtual Compton Scattering off the Neutron

    SciTech Connect

    Mazouz, M.; Guillon, B.; Real, J.-S.; Voutier, E.

    2007-12-14

    The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e-vector,e{sup '}{gamma})X cross section measured at Q{sup 2}=1.9 GeV{sup 2} and x{sub B}=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E{sub q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

  14. Deeply virtual Compton scattering and nucleon structure

    SciTech Connect

    M. Garcon

    2006-11-01

    Deeply Virtual Compton Scattering (DVCS) is the tool of choice to study Generalized Parton Distributions (GPD) in the nucleon. After a general introduction to the subject, a review of experimental results from various facilities is given. Following the first encouraging results, new generation dedicated experiments now allow unprecedented precision and kinematical coverage. Several new results were presented during the conference, showing significant progress in this relatively new field. Prospects for future experiments are presented. The path for the experimental determination of GPDs appears now open.

  15. Deeply virtual compton scattering off the neutron.

    PubMed

    Mazouz, M; Camsonne, A; Camacho, C Muñoz; Ferdi, C; Gavalian, G; Kuchina, E; Amarian, M; Aniol, K A; Beaumel, M; Benaoum, H; Bertin, P; Brossard, M; Chen, J-P; Chudakov, E; Craver, B; Cusanno, F; de Jager, C W; Deur, A; Feuerbach, R; Fieschi, J-M; Frullani, S; Garçon, M; Garibaldi, F; Gayou, O; Gilman, R; Gomez, J; Gueye, P; Guichon, P A M; Guillon, B; Hansen, O; Hayes, D; Higinbotham, D; Holmstrom, T; Hyde, C E; Ibrahim, H; Igarashi, R; Jiang, X; Jo, H S; Kaufman, L J; Kelleher, A; Kolarkar, A; Kumbartzki, G; Laveissiere, G; Lerose, J J; Lindgren, R; Liyanage, N; Lu, H-J; Margaziotis, D J; Meziani, Z-E; McCormick, K; Michaels, R; Michel, B; Moffit, B; Monaghan, P; Nanda, S; Nelyubin, V; Potokar, M; Qiang, Y; Ransome, R D; Réal, J-S; Reitz, B; Roblin, Y; Roche, J; Sabatié, F; Saha, A; Sirca, S; Slifer, K; Solvignon, P; Subedi, R; Sulkosky, V; Ulmer, P E; Voutier, E; Wang, K; Weinstein, L B; Wojtsekhowski, B; Zheng, X; Zhu, L

    2007-12-14

    The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e,e'gamma)X cross section measured at Q2=1.9 GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E_{q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced. PMID:18233443

  16. Deeply Virtual Compton Scattering off the neutron

    SciTech Connect

    M. Mazouz; A. Camsonne; C. Munoz Camacho; C. Ferdi; G. Gavalian; E. Kuchina; M. Amarian; K. A. Aniol; M. Beaumel; H. Benaoum; P. Bertin; M. Brossard; J.-P. Chen; E. Chudakov; B. Craver; F. Cusanno; C.W. de Jager; A. Deur; R. Feuerbach; J.-M. Fieschi; S. Frullani; M. Garcon; F. Garibaldi; O. Gayou; R. Gilman; J. Gomez; P. Gueye; P.A.M. Guichon; B. Guillon; O. Hansen; D. Hayes; D. Higinbotham; T. Holmstrom; C.E. Hyde; H. Ibrahim; R. Igarashi; X. Jiang; H.S. Jo; L.J. Kaufman; A. Kelleher; A. Kolarkar; G. Kumbartzki; G. Laveissiere; J.J. LeRose; R. Lindgren; N. Liyanage; H.-J. Lu; D.J. Margaziotis; Z.-E. Meziani; K. McCormick; R. Michaels; B. Michel; B. Moffit; P. Monaghan; S. Nanda; V. Nelyubin; M. Potokar; Y. Qiang; R.D. Ransome; J.-S. Real; B. Reitz; Y. Roblin; J. Roche; F. Sabatie; A. Saha; S. Sirca; K. Slifer; P. Solvignon; R. Subedi; V. Sulkosky; P.E. Ulmer; E. Voutier; K. Wang; L.B. Weinstein; B. Wojtsekhowski; X. Zheng; L. Zhu

    2007-12-01

    The present experiment exploits the interference between the Deeply Virtual Compton Scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to $E_q$, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

  17. Effect of supercooling and cell volume on intracellular ice formation.

    PubMed

    Prickett, Richelle C; Marquez-Curtis, Leah A; Elliott, Janet A W; McGann, Locksley E

    2015-04-01

    Intracellular ice formation (IIF) has been linked to death of cells cryopreserved in suspension. It has been assumed that cells can be supercooled by 2 to 10°C before IIF occurs, but measurements of the degree of supercooling that cells can tolerate are often confounded by changing extracellular temperature and solutions of different osmolality (which affect the cell volume). The purpose of this study was to examine how the incidence of IIF in the absence of cryoprotectants is affected by the degree of supercooling and cell volume. Human umbilical vein endothelial cells were suspended in isotonic (300 mOsm) and hypertonic (∼600 to 700 mOsm) solutions and exposed to supercooling ranging from 2 to 10°C before extracellular ice was nucleated. The number of cells undergoing IIF was examined in a cryostage (based on the darkening of cells upon intracellular freezing ("flashing")) as a function of the degree of supercooling, and cell survival post-thaw was assessed using a membrane integrity assay. We found that while the incidence of IIF increased with supercooling in both isotonic and hypertonic solutions, it was higher in the isotonic solution at any given degree of supercooling. Since cells in hypertonic solution were shrunken due to water efflux, we hypothesized that the difference in IIF behavior could be attributed to the decreased volume of cells in the hypertonic solution. Our results confirm that cells with a smaller diameter before extracellular ice nucleation have a decreased probability of IIF and suggest that cell volume could play a more significant role in the incidence of IIF than the extracellular ice nucleation temperature. PMID:25707695

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Clusters of mobile molecules in supercooled water

    NASA Astrophysics Data System (ADS)

    Giovambattista, Nicolas; Buldyrev, Sergey V.; Stanley, H. Eugene; Starr, Francis W.

    2005-07-01

    We study the spatially heterogeneous dynamics in water via molecular dynamics simulations using the extended simple point charge potential. We identify clusters formed by mobile molecules and study their properties. We find that these clusters grow in size and become more compact as temperature decreases. We analyze the probability density function of cluster size, and we study the cluster correlation length. We find that clusters appear to be characterized by a fractal dimension consistent with that of lattice animals. We relate the cluster size and correlation length to the configurational entropy, Sconf . We find that these quantities depend weakly on 1/Sconf . In particular, the linearity found between the cluster mass n* and 1/Sconf suggests that n* may be interpreted as the mass of the cooperatively rearranging regions that form the basis of the Adam-Gibbs approach to the dynamics of supercooled liquids. We study the motion of molecules within a cluster, and find that each molecule preferentially follows a neighboring molecule in the same cluster. Based on this finding we hypothesize that stringlike cooperative motion may be a general mechanism for molecular rearrangement of complex, as well as simple liquids. By mapping each equilibrium configuration onto its corresponding local potential energy minimum or inherent structure (IS), we are able to compare the mobile molecule clusters in the equilibrium system with the molecules forming the clusters identified in the transitions between IS. We find that (i) mobile molecule clusters obtained by comparing different system configurations and (ii) clusters obtained by comparing the corresponding IS are completely different for short time scales, but are the same on the longer time scales of diffusive motion.

  20. Isothermal transformation of supercooled liquid n -butanol near the glass transition: Polyamorphic transitions in molecular liquids investigated using Raman scattering

    NASA Astrophysics Data System (ADS)

    Wypych, Aleksandra; Guinet, Yannick; Hédoux, Alain

    2007-10-01

    Raman investigations were carried out during an isothermal transformation of deeply supercooled liquid n -butanol, recently interpreted as a polyamorphic transition. Raman spectra indicate that the newly emerging state is a mixed crystal-liquid state, and not another amorphous state. The long-range order in crystallites was identified as reflecting that of the crystal. The time dependence of the O-H stretch spectrum indicates that the transformation is driven by the formation of a two-dimensional H-bonded network, according to the archetypal-layered structures of normal alcohols. The origin of the frustration of the crystallization in n -butanol can be explained from the consideration that the rearrangement of the hydrogen-bonded molecules is unavoidably prevented by the very low molecular mobility of the system only two degrees above Tg .

  1. Effect of a Magnetic Field on Drosophila under Supercooled Conditions

    PubMed Central

    Mihara, Makoto; Terayama, Hayato; Hatayama, Naoyuki; Hayashi, Shogo; Matsushita, Masayuki; Itoh, Masahiro

    2012-01-01

    Under subzero degree conditions, free water contained in biological cells tends to freeze and then most living things die due to low temperatures. We examined the effect of a variable magnetic field on Drosophila under supercooled conditions (a state in which freezing is not caused even below the freezing point). Under such supercooled conditions with the magnetic field at 0°C for 72 hours, −4°C for 24 hours and −8°C for 1 hour, the Drosophila all survived, while all conversely died under the supercooled conditions without the magnetic field. This result indicates a possibility that the magnetic field can reduce cell damage caused due to low temperatures in living things. PMID:23284809

  2. Effect of a magnetic field on Drosophila under supercooled conditions.

    PubMed

    Naito, Munekazu; Hirai, Shuichi; Mihara, Makoto; Terayama, Hayato; Hatayama, Naoyuki; Hayashi, Shogo; Matsushita, Masayuki; Itoh, Masahiro

    2012-01-01

    Under subzero degree conditions, free water contained in biological cells tends to freeze and then most living things die due to low temperatures. We examined the effect of a variable magnetic field on Drosophila under supercooled conditions (a state in which freezing is not caused even below the freezing point). Under such supercooled conditions with the magnetic field at 0°C for 72 hours, -4°C for 24 hours and -8°C for 1 hour, the Drosophila all survived, while all conversely died under the supercooled conditions without the magnetic field. This result indicates a possibility that the magnetic field can reduce cell damage caused due to low temperatures in living things. PMID:23284809

  3. Method and apparatus for supercooling and solidifying substances

    NASA Technical Reports Server (NTRS)

    Lacy, L. L.; Robinson, M. B.; Rathz, T. J.; Katz, L.; Nisen, D. B. (Inventor)

    1983-01-01

    An enclosure provides a containerless environment in which a sample specimen is positioned. The specimen is heated in the containerless environment, and the specimen melt is dropped through the tube in which it cools by radiation. The tube is alternatively backfilled with an inert gas whereby the specimen melt cools by both radiation and convection during its free fall. During the free fall, the sample is in a containerless, low-gravity environment which enhances supercooling in the sample and prevents sedimentation and thermal convection influences. The sample continues to supercool until nucleation occurs which is detected by silicon photovoltaic detectors. The sample solidifies after nucleation and becomes completely solid before entering the detachable catcher. The amount of supercooling of the specimen can be measured by knowing the cooling ratio and determining the time for nucleation to occur.

  4. Supercooling and energy exchange near the Arctic Ocean surface

    NASA Astrophysics Data System (ADS)

    Lewis, E. L.; Perkin, R. G.

    1983-09-01

    Conductivity, temperature, and depth (CTD) measurements made north of Svalbard, centered around 83°N, 10°E, show regions in which the surface waters are supercooled to a depth of about 8 m. At other locations, warm Atlantic waters advected into the area by the West Spitzbergen current are melting the sea ice. The resulting large horizontal salinity gradients cause intrusive layering with layers at depth sometimes being below their surface freezing point. Supercooling is explained in terms of the pressure dependence of freezing temperature and the existence of ice keels well below the surface. It is noted that the potential heat sink for surface freezing provided by supercooling can be of the same order as that available from heat loss to the atmosphere. At the same time an equivalent amount of ice is being melted off the keels thus constituting an "ice pump."

  5. Supercooling and structure of levitation melted Fe-Ni alloys

    NASA Technical Reports Server (NTRS)

    Abbaschian, G. J.; Flemings, M. C.

    1983-01-01

    A study has been made of the effect of supercooling, quenching rate, growth inhibitors, and grain refiners on the structure of levitation-melted Fe- 25 pct Ni alloys. A combination of three morphologies, dendritic, spherical, and mixed dendritic and spherical, is observed in samples superheated or supercooled by less than 175 K. At larger supercooling, however, only the spherical morphology is observed. The grain size and the grain boundary shape are found to be strongly dependent on the subgrain morphology but not on the quenching temperature. Considerable grain growth is evident in samples with spherical and mixed morphologies but not in the dendriitic samples. The average cooling rates during solidification and the heat transfer coefficients at the metal-quenching medium boundary are calculated. For samples solidified in water, molten lead, and ceramic molds, the heat transfer coefficients are 0.41, 0.52, and 0.15 w/sq cm, respectively.

  6. Unitarity constraints on deeply virtual Compton scattering

    NASA Astrophysics Data System (ADS)

    Laget, J. M.

    2007-11-01

    At moderately low momentum transfer (-t up to 1 GeV2) the coupling to the vector meson production channels gives the dominant contribution to real Compton and deeply virtual Compton scattering (DVCS). Starting from a Regge pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment explains not only the unexpectedly large DVCS unpolarized cross section that has been recently measured at Jefferson Laboratory (JLab), but also all the beam spin and charge asymmetries that have been measured at JLab and Hermes, without explicit need of Generalized Parton Distributions (GPD). The issue of the relationship between the two approaches is addressed.

  7. Unitary constraints on Deeply Virtual Compton Scattering

    SciTech Connect

    J.M. Laget

    2007-11-01

    At moderately low momentum transfer ($-t$ up to 1 GeV$^2$) the coupling to the vector meson production channels gives the dominant contribution to real Compton and deeply virtual Compton scattering (DVCS). Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment explains not only the unexpectedly large DVCS unpolarized cross section that has been recently measured at Jefferson Laboratory (JLab), but also all the beam spin and charge asymmetries that has been measured at JLab and Hermes, without explicit need of Generalized Parton Distributions (GPD). The issue of the relationship between the two approaches is addressed.

  8. Cotranslational folding of deeply knotted proteins

    NASA Astrophysics Data System (ADS)

    Chwastyk, Mateusz; Cieplak, Marek

    2015-09-01

    Proper folding of deeply knotted proteins has a very low success rate even in structure-based models which favor formation of the native contacts but have no topological bias. By employing a structure-based model, we demonstrate that cotranslational folding on a model ribosome may enhance the odds to form trefoil knots for protein YibK without any need to introduce any non-native contacts. The ribosome is represented by a repulsive wall that keeps elongating the protein. On-ribosome folding proceeds through a a slipknot conformation. We elucidate the mechanics and energetics of its formation. We show that the knotting probability in on-ribosome folding is a function of temperature and that there is an optimal temperature for the process. Our model often leads to the establishment of the native contacts without formation of the knot.

  9. Cotranslational folding of deeply knotted proteins.

    PubMed

    Chwastyk, Mateusz; Cieplak, Marek

    2015-09-01

    Proper folding of deeply knotted proteins has a very low success rate even in structure-based models which favor formation of the native contacts but have no topological bias. By employing a structure-based model, we demonstrate that cotranslational folding on a model ribosome may enhance the odds to form trefoil knots for protein YibK without any need to introduce any non-native contacts. The ribosome is represented by a repulsive wall that keeps elongating the protein. On-ribosome folding proceeds through a a slipknot conformation. We elucidate the mechanics and energetics of its formation. We show that the knotting probability in on-ribosome folding is a function of temperature and that there is an optimal temperature for the process. Our model often leads to the establishment of the native contacts without formation of the knot. PMID:26292194

  10. Supercooling Preservation Of The Rat Liver For Transplantation

    PubMed Central

    Bruinsma, Bote G.; Berendsen, Tim A.; Izamis, Maria-Louisa; Yeh, Heidi; Yarmush, Martin L.; Uygun, Korkut

    2015-01-01

    The current standard for liver preservation is limited in duration. Employing a novel subzero preservation technique that includes supercooling and machine perfusion can significantly improve preservation and prolong storage times. By loading rat livers with cryoprotectants to prevent both intra- and extracellular ice formation and protect against hypothermic injury, livers can be cooled to −6 °C without freezing and kept viable for up to 96 hours. Here, we describe the procedures of loading cryoprotectants by means of subnormothermic machine perfusion (SNMP), controlled cooling to a supercooled state, followed by SNMP recovery and orthotopic liver transplantation. PMID:25692985

  11. Polarized View of Supercooled Liquid Water Clouds

    NASA Technical Reports Server (NTRS)

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

    2016-01-01

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

  12. Thermodynamics of Supercooled and Glassy Water

    NASA Astrophysics Data System (ADS)

    Debenedetti, Pablo G.

    1998-03-01

    The behavior of metastable water at low temperatures is unusual. The isothermal compressibility, the isobaric heat capacity, and the magnitude of the thermal expansion coefficient increase sharply upon supercooling, and structural relaxation becomes extremely sluggish at temperatures far above the glass transition(Angell, C.A., Annu. Rev. Phys. Chem., 34, 593, 1983)(Debenedetti, P.G., Metastable Liquids. Concepts and Principles, Princeton University Press, 1996). Water has two distinct glassy phases, low- and high-density amorphous ice (LDA, HDA). The transition between LDA and HDA is accompanied by sharp volume and enthalpy changes, and appears to be first-order(Mishima, O., L.D.Calvert, and E. Whalley, Nature, 314, 76, 1985)(Mishima, O., J. Chem. Phys., 100, 5910, 1994). The understanding of these observations in terms of an underlying global phase behavior remains incomplete(Speedy, R.J., J. Phys. Chem., 86, 982, 1982)(Poole, P.H., F. Sciortino, U. Essman, and H.E. Stanley, Nature, 360, 324, 1992)(Sastry, S., P.G. Debenedetti, F. Sciortino, and H.E. Stanley, Phys. Rev. E, 53, 6144, 1996)(Tanaka, H., Nature, 380, 328, 1996)(Xie, Y., K.F. Ludwig, G. Morales, D.E. Hare, and C.M. Sorensen, Phys. Rev. Lett., 71, 2050, 1993). Microscopic theories and computer simulations suggest several scenarios that can reproduce some experimental observations. Interesting and novel ideas have resulted from this body of theoretical work, such as the possibility of liquid-liquid immiscibility in a pure substance(Poole, P.H., F.Sciortino, T.Grande, H.E. Stanley, and C.A. Angell, Phys. Rev. Lett., 73, 1632, 1994)(Roberts, C.J., and P.G. Debenedetti, J. Chem. Phys., 105, 658, 1996)(Roberts, C.J., P.G. Debenedetti, and A.Z. Panagiotopoulos, Phys. Rev. Lett., 77, 4386, 1996)(Harrington, S., R. Zhang, P.H. Poole, F. Sciortino, and H.E. Stanley, Phys. Rev. Lett., 78, 2409, 1997). In this talk I will review the experimental facts, discuss their theoretical interpretation, and identify key

  13. Deeply weathered basement rocks in Norway

    NASA Astrophysics Data System (ADS)

    Bönner, Marco; Knies, Jochen; Fredin, Ola; Olesen, Odleiv; Viola, Giulio

    2014-05-01

    Recent studies show that, in addition to tectonic processes, surface processes have also had a profound impact on the topography of Norway. This is especially obvious for the northernmost part of the Nordland county and for western Norway, where the current immature Alpine-type topography cannot be easily explained by tectonic processes only. Erosion of the sedimentary succession also does not seem sufficient to explain the observed relief. Common remnants of deeply weathered basement rocks, however, indicate a history of deep alteration and later erosion of the bedrock, which needs to be considered as another important factor in the development of the topographic relief. Most of the sites with deeply weathered basement exhibit a clay-poor grussy type of weathering, which is generally considered to be of relatively young age (Plio-/Pleistocene) and thought to represent an intermediate stage of weathering. Unfortunately, small amounts or complete absence of clay minerals in these weathering products precluded the accurate dating of this weathered material. Scandinavia was exposed to a large range of glaciations and the once extensive sedimentary successions have been almost entirely eroded, which impedes a minimum age estimate of the weathering profile. Although several sites preserving remnants of deep weathering can still be observed onshore Norway, they are all covered by Quaternary overburden and the age of the regolith remains thus unconstrained and a matter of debate. The only exception is a small Mesozoic basin on Andøya, northern Norway, where weathered and clay-poor saprolite was found underlying Jurassic and Cretaceous sedimentary rocks. Over the last few years the Geological Survey of Norway (NGU) has mapped and investigated deep weathering onshore Norway to better understand weathering processes and to constrain the age of the weathering remnants. The combined interpretation of geophysical, mineralogical and geochemical data, together with recent

  14. Fast Scanning Calorimetry Studies of Supercooled Liquids and Glasses

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Deepanjan

    This dissertation is a compilation of research results of extensive Fast Scanning Calorimetry studies of two non-crystalline materials: Toluene and Water. Motivation for fundamental studies of non-crystalline phases, a brief overview of glassy materials and concepts and definitions related to them is provided in Chapter 1. Chapter 2 provides fundamentals and details of experimental apparata, experimental protocol and calibration procedure. Chapter 3 & 4 provides extensive studies of stable non-crystalline toluene films of micrometer and nanometer thicknesses grown by vapor deposition at distinct deposition rates and temperatures and probed by Fast Scanning Calorimetry. Fast scanning calorimetry is shown to be extremely sensitive to the structure of the vapor-deposited phase and was used to characterize simultaneously its kinetic stability and its thermodynamic properties. According to our analysis, transformation of vapor -deposited samples of toluene during heating with rates in excess 100,000 K/s follows the zero-order kinetics. The transformation rate correlates strongly with the initial enthalpy of the sample, which increases with the deposition rate according to sub-linear law. Analysis of the transformation kinetics of vapor deposited toluene films of various thicknesses reveal a sudden increase in the transformation rate for films thinner than 250 nm. The change in kinetics correlates with the surface roughness scale of the substrate, which is interpreted as evidence for kinetic anisotropy of the samples. We also show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited (VD) films of toluene are distinct from those of ordinary supercooled (OS) phase even when the deposition takes place at temperatures above the glass softening (Tg). The implications of these findings for the formation mechanism and structure of vapor deposited stable glasses are discussed. Chapter 5 and 6 provide detailed Fast Scanning Calorimetry studies

  15. Jamming, relaxation, and crystallization of a supercooled fluid in a three-dimensional lattice.

    PubMed

    Levit, H; Rotman, Z; Eisenberg, E

    2012-01-01

    Off-equilibrium dynamics of a three-dimensional lattice model with nearest- and next-nearest-neighbors exclusions is studied. At equilibrium, the model undergoes a first-order fluid-solid transition. Nonequilibrium filling, through random sequential adsorption with diffusion, creates amorphous structures and terminates at a disordered state with random closest packing density that lies in the equilibrium solid regime. The approach toward random closest packing is characterized by two distinct power-law regimes, reflecting the formation of small densely packed grains in the long-time regime of the filling process. We then study the fixed-density relaxation of these amorphous structures toward the solid phase. The route to crystallization for the high-density, deeply supercooled regime is shown to deviate from the simple grain growth proposed by classical nucleation theory. Our measurements suggest that relaxation in this regime is driven mainly by coalescence of neighboring crystallized grains which exist in the initial amorphous state. PMID:22400572

  16. Structure factor changes in supercooled yttria-alumina

    SciTech Connect

    Wilding, Martin C.; Greaves, G. Neville; Quang Vu Van; Majerus, Odile; Hennet, Louis

    2009-01-29

    Changes in the structure factor of yttria-alumina liquids have been identified in the supercooled range. Different inter-polyhedral configurations between AlO{sub 4} and YO{sub 6} groups distinguish low density and high density liquid phases. The coexistence of phases at high temperatures have been identified in simultaneous measurements of small angle x-ray scattering.

  17. Dynamic transitions in molecular dynamics simulations of supercooled silicon

    NASA Astrophysics Data System (ADS)

    Mei, Xiaojun; Eapen, Jacob

    2013-04-01

    Two dynamic transitions or crossovers, one at a low temperature (T* ≈ 1006 K) and the other at a high temperature (T0 ≈ 1384 K), are shown to emerge in supercooled liquid silicon using molecular dynamics simulations. The high-temperature transition (T0) marks the decoupling of stress, density, and energy relaxation mechanisms. At the low-temperature transition (T*), depending on the cooling rate, supercooled silicon can either undergo a high-density-liquid to low-density-liquid (HDL-LDL) phase transition or experience an HDL-HDL crossover. Dynamically heterogeneous domains that emerge with supercooling become prominent across the HDL-HDL transition at 1006 K, with well-separated mobile and immobile regions. Interestingly, across the HDL-LDL transition, the most mobile atoms form large prominent aggregates while the least mobile atoms get spatially dispersed akin to that in a crystalline state. The attendant partial return to spatial uniformity with the HDL-LDL phase transition indicates a dynamic mechanism for relieving the frustration in supercooled states.

  18. Experimental Study of Sudden Solidification of Supercooled Water

    ERIC Educational Resources Information Center

    Bochnícek, Zdenek

    2014-01-01

    The two independent methods of measurement of the mass of ice created at sudden solidification of supercooled water are described. One is based on the calorimetric measurement of heat that is necessary for melting the ice and the second interprets the volume change that accompanies the water freezing. Experimental results are compared with the…

  19. Development of Active Control Method for Supercooling Releasing of Water

    NASA Astrophysics Data System (ADS)

    Mito, Daisuke; Kozawa, Yoshiyuki; Tanino, Masayuki; Inada, Takaaki

    We have tested the prototype ice-slurry generator that enables both production of supercooled water (-2°C) and releasing of its supercooling simultaneously and continuously in a closed piping system. In the experiment, we adopted the irradiation of ultrasonic wave as an active control method of triggering for supercooling releasing, and evaluated the reliability for a practical use compared with the seed ice-crystal trigger. As the results, it has been confirmed that the ultrasonic wave trigger acts assuredly at the same level of degree of supercooling as that by using the seed ice-crystal Trigger. Moreover, it can be found that the ultrasonic wave trigger has the advantage of removing the growing ice-crystals on the pipe wall at the same time. Finally, we have specified the bombardment condition of ultrasonic wave enough to make continuously the ice-slurry in a closed system as the output surface power density > 31.4kW/m2 and the superficial bombardment time > 4.1sec. We have also demonstrated the continuous ice-slurry making for more than 6hours by using the refrigerator system with the practical scale of 88kW.

  20. Entropy Calculations for a Supercooled Liquid Crystalline Blue Phase

    ERIC Educational Resources Information Center

    Singh, U.

    2007-01-01

    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…

  1. Supercooling points of Lysiphlebus testaceipes and its host Schizaphis graminum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Supercooling points (SCPs) were measured for various life stages of male and female Lysiphlebus testaceipes (Cresson) parasitoids, along with mummies and its aphid host, Schizaphis graminum (Rondani). Some parasitoids were acclimated (4 h at 10°C before cooling down to the SCP) to determine whether...

  2. Adaptive elastic networks as models of supercooled liquids

    NASA Astrophysics Data System (ADS)

    Yan, Le; Wyart, Matthieu

    2015-08-01

    The thermodynamics and dynamics of supercooled liquids correlate with their elasticity. In particular for covalent networks, the jump of specific heat is small and the liquid is strong near the threshold valence where the network acquires rigidity. By contrast, the jump of specific heat and the fragility are large away from this threshold valence. In a previous work [Proc. Natl. Acad. Sci. USA 110, 6307 (2013), 10.1073/pnas.1300534110], we could explain these behaviors by introducing a model of supercooled liquids in which local rearrangements interact via elasticity. However, in that model the disorder characterizing elasticity was frozen, whereas it is itself a dynamic variable in supercooled liquids. Here we study numerically and theoretically adaptive elastic network models where polydisperse springs can move on a lattice, thus allowing for the geometry of the elastic network to fluctuate and evolve with temperature. We show numerically that our previous results on the relationship between structure and thermodynamics hold in these models. We introduce an approximation where redundant constraints (highly coordinated regions where the frustration is large) are treated as an ideal gas, leading to analytical predictions that are accurate in the range of parameters relevant for real materials. Overall, these results lead to a description of supercooled liquids, in which the distance to the rigidity transition controls the number of directions in phase space that cost energy and the specific heat.

  3. Deeply Virtual Compton Scattering off 4He

    NASA Astrophysics Data System (ADS)

    Joosten, Sylvester; CLAS Collaboration

    2015-10-01

    The European Muon Collaboration (EMC) observed the first signs of a modification of the partonic structure of the nucleon when present in a nuclear medium. The precise nature of these effects, as well as their underlying cause, is yet to be determined. The generalized parton distribution (GPD) framework provides a powerful tool to study the partonic structure of nucleons inside a nucleus. Hard exclusive leptoproduction of a real photon off a nucleon, deeply virtual Compton scattering (DVCS), is presently considered the cleanest experimental access to the GPDs, through the Compton form factors (CFFs). This is especially the case for scattering off the spin-zero helium nucleus, where only a single CFF contributes to the process. The real and imaginary parts of this CFF can be constrained through the beam-spin asymmetry (BSA). We will present the first measurements of the DVCS process off 4He using the CEBAF 6 GeV polarized electron beam and the CLAS detector at JLab. The CLAS detector was supplemented with an inner electromagnetic calorimeter for photons produced at small angles, as well as a radial time projection chamber (RTPC) to detect low-energy recoil nuclei. This setup allowed for a clean measurement of the BSA in both the coherent and incoherent channels.

  4. Thermodynamic properties of bulk and confined water

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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 (TL ≃ 225 K). The second, T* ˜ 315 ± 5 K, is a special locus of the isothermal compressibility KT(T, P) and the thermal expansion coefficient αP(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 (TL) and the onset of the unfolding process (T*).

  5. Thermodynamic properties of bulk and confined water

    SciTech Connect

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

    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 *})

  6. Analysis of supercooling activity of tannin-related polyphenols.

    PubMed

    Kuwabara, Chikako; Wang, Donghui; Endoh, Keita; Fukushi, Yukiharu; Arakawa, Keita; Fujikawa, Seizo

    2013-08-01

    Based on the discovery of novel supercooling-promoting hydrolyzable gallotannins from deep supercooling xylem parenchyma cells (XPCs) in Katsura tree (see Wang et al. (2012) [38]), supercooling capability of a wide variety of tannin-related polyphenols (TRPs) was examined in order to find more effective supercooling-promoting substances for their applications. The TRPs examined were single compounds including six kinds of hydrolyzable tannins, 11 kinds of catechin derivatives, two kinds of structural analogs of catechin and six kinds of phenolcarboxylic acid derivatives, 11 kinds of polyphenol mixtures and five kinds of crude plant tannin extracts. The effects of these TRPs on freezing were examined by droplet freezing assays using various solutions containing different kinds of identified ice nucleators such as the ice nucleation bacterium (INB) Erwinia ananas, the INB Xanthomonas campestris, silver iodide and phloroglucinol as well as a solution containing only unintentionally included unidentified airborne ice nucleators. Among the 41 kinds of TRPs examined, all of the hydrolyzable tannins, catechin derivatives, polyphenol mixtures and crude plant tannin extracts as well as a few structural analogs of catechin and phenolcarboxylic acid derivatives exhibited supercooling-promoting activity (SCA) with significant differences (p>0.05) from at least one of the solutions containing different kinds of ice nucleators. It should be noted that there were no TRPs exhibiting ice nucleation-enhancing activity (INA) in all solutions containing identified ice nucleators, whereas there were many TRPs exhibiting INA with significant differences in solutions containing unidentified ice nucleators alone. An emulsion freezing assay confirmed that these TRPs did not essentially affect homogeneous ice nucleation temperatures. It is thought that not only SCA but also INA in the TRPs are produced by interactions with heterogeneous ice nucleators, not by direct interaction with water

  7. Diminution of supercooling of electrolytes by carbon particles

    SciTech Connect

    Ding, S.P.; Xu, K.; Zhang, S.S.; Jow, T.R.; Amine, K.; Henriksen, G.L.

    1999-11-01

    A liquid solution composed of a pure or mixed solvent and a dissolved salt is the most common form of electrolyte used in electrochemical devices for energy storage and conversion, such as batteries and capacitors. For such an electrolyte, one of the most important properties is its crystallization temperature, which limits the low-temperature operation of a device containing such an electrolyte. If thermodynamic equilibria were strictly followed, crystallization of an electrolyte would start as soon as it is cooled to its liquidus temperature. But such is seldom the case, as an electrolyte by itself often supercools well below this temperature. This supercooling can delay or even eliminate the crystallization of an electrolyte, thus substantially extending its apparent liquid range. The authors studied the supercooling behavior of a number of solutions of LiPF{sub 6} in ethylene carbonate-ethyl methyl carbonate in 1:1 weight ratio with and without the presence of one of these carbons: activated carbon, carbon black, and mesocarbon microbeads. The results of differential scanning calorimetry (DSC) show that the supercooling of less concentrated solutions is significantly diminished by the presence of a carbon, the degree and the nature of which depends on the concentration of the electrolyte and the type of carbon present. The results of conductivity measurements also indicate precipitation in some of the electrolytes at low temperatures, which correlates well with the DSC results. The authors therefore conclude that the temperature range in which an electrolyte supercools without a nucleating material is unreliable for the operation of an electrochemical device containing such an electrolyte. Instead, the liquidus temperature of an electrolyte should be used as the lower limit of operation if the possibility of its crystallization is to be excluded.

  8. Shear viscosity of a supercooled polymer melt via nonequilibrium molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Varnik, F.; Binder, K.

    2002-10-01

    Using nonequilibrium molecular dynamics simulations, we compute the shear viscosity, ηs, of a glass forming polymer melt at temperatures ranging from the normal liquid state down to the supercooled state. For this purpose, the polymer melt is confined between two solid walls and a constant force pointing in direction parallel to the walls is applied on each monomer thus giving rise to a Poiseuille flow. It is shown that ηs(T) does not exhibit an Arrhenius-type behavior but can be described both by a power law (mode coupling theory) and by a Vogel-Fulcher-Tammann law. A similar behavior is observed in recent experiments above the glass transition temperature. The diffusion coefficient is computed using the mean square displacements in direction perpendicular to the flow. Combined with the knowledge of ηs(T), it is then shown that the Stokes-Einstein relation is valid at high temperatures, whereas deviations are observed in the supercooled regime in agreement with experiments. Moreover, the local viscosity, η(z), is also computed and its reliability is discussed. Using the sharp rise of η(z) close to the wall, we estimate zwall, the effective position of the wall. It is found that zwall moves towards the film center at lower T thus leading to a decrease of the (hydrodynamic) width of the system. Furthermore, we observe that the curves for η(z)/ηs at various temperatures superimpose if the data are depicted versus z-zwall(T). This suggests that the spatial and temperature dependence of the local viscosity separate if the effective position of the wall is chosen as a new reference plane.

  9. Connections between structural jamming, local metabasin features, and relaxation dynamics in a supercooled glassy liquid

    NASA Astrophysics Data System (ADS)

    Frechero, M. A.; Alarcón, L. M.; Schulz, E. P.; Appignanesi, G. A.

    2007-01-01

    Dynamics in glass-forming liquids in the supercooled regime vary considerably from one point of the sample to another suggesting the existence of regions with different degrees of jamming. In fact, the existence of relatively compact regions with particles with an enhanced propensity for motion has been detected in model glassy systems. In turn, the structural relaxation has been shown to be accomplished by means of a series of fast transitions between metabasins in the potential energy landscape involving the collective motion of a substantial number of particles arranged in relatively compact clusters (democratic clusters or d clusters). In this work we shall complete this picture by identifying the connections between local structural jamming, metabasin confining strength, and d clusters. Thus we shall demonstrate that the degree of jamming of the local structure dictates the confining strength of the local metabasin and that the local high propensity regions and the d clusters are not only similar in nature but that they share a significant amount of particles.

  10. Confinement as a Tool to Probe Amorphous Order

    NASA Astrophysics Data System (ADS)

    Cammarota, Chiara; Gradenigo, Giacomo; Biroli, Giulio

    2013-09-01

    We study the effect of confinement on glassy liquids using random first order transition theory as a framework. We show that the characteristic length scale above which confinement effects become negligible is related to the point-to-set length scale introduced to measure the spatial extent of amorphous order in supercooled liquids. By confining below this characteristic size, the system becomes a glass. Eventually, for very small sizes, the effect of the boundary is so strong that any collective glassy behavior is wiped out. We clarify similarities and differences between the physical behaviors induced by confinement and by pinning particles outside a spherical cavity (the protocol introduced to measure the point-to-set length). Finally, we discuss possible numerical and experimental tests of our predictions.

  11. Shear-accelerated crystallization in a supercooled atomic liquid

    NASA Astrophysics Data System (ADS)

    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 γ˙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.

  12. Diffusion-viscosity decoupling in supercooled glycerol aqueous solutions.

    PubMed

    Trejo González, José A; Longinotti, M Paula; Corti, Horacio R

    2015-01-01

    The diffusion of ferrocene methanol in supercooled glycerol-water mixtures has been measured over a wide viscosity range, which allowed analyzing the composition dependence of the Stokes-Einstein breakdown (diffusion-viscosity decoupling). The observed decoupling exhibits a common behavior for all studied compositions (glycerol mass fractions between 0.7 and 0.9), determined by the reduced temperature (T/Tg) of the mixtures. This result differs from that reported previously for the diffusion of glycerol in its aqueous solutions, where the reduced temperature for the decoupling decreases with increasing water content. We conclude that the contradictory results are only apparent, and they can be explained by the use of inconsistent extrapolated values of the viscosity of the glycerol-water mixtures in the supercooled region. PMID:25478790

  13. Structure analysis methods for crystalline solids and supercooled liquids

    NASA Astrophysics Data System (ADS)

    Yu, Da-Qi; Chen, Min; Han, Xiu-Jun

    2005-11-01

    The three most widely used methods for analyzing atomic structures are evaluated by simulating crystalline solids and supercooled liquids. The local order parameter approach due to Volkov [Phys. Rev. E 66, 061401 (2002)] fails in randomly perturbed body-centered-cubic environments, while the pair analysis method behaves as an approximate approach depending on how the neighborhood is defined. As to the Voronoi analysis method, we improve the procedure of Brostow [Phys. Rev. B 57, 13448 (1998)] to eliminate distorted Voronoi faces and edges which originate from thermal vibrations and computational rounding errors. The improved procedure works robustly in face-centered-cubic, body-centered-cubic, and hexagonal close-packed environments. When the pair analysis technique and the Voronoi analysis method are applied to detect the microstructure and its evolution in supercooled liquids, qualitatively consistent results are attained.

  14. The hydrology of subglacial overdeepenings: A new supercooling threshold formula

    NASA Astrophysics Data System (ADS)

    Werder, Mauro A.

    2016-03-01

    Overdeepenings are a hallmark glacial landform of broad geomorphologlogical and glaciological interest. Their formation mechanism has not yet been fully uncovered, but subglacial drainage is likely a key factor. One prominent hypothesis states that the depth of an overdeepening stabilizes at the supercooling threshold. This threshold is reached when the adverse bed slope terminating an overdeepening is sufficiently large to shut down the efficient, channelized drainage system. Classic theory puts this threshold at a ratio of bed to surface slope of -1.6. Here I extend that theory by taking into account that downstream water pressure can be below overburden pressure. The new formula agrees well with results from one- and two-dimensional subglacial drainage models. Applying it to observations of 147 overdeepenings from alpine glaciers and ice sheets shows that the depth of overdeepenings rarely exceeds the new supercooling threshold. Thus, this work supports the stabilizing hypothesis.

  15. Dynamics in a supercooled molecular liquid: Theory and simulations

    SciTech Connect

    Rinaldi, Adele; Sciortino, Francesco; Tartaglia, Piero

    2001-06-01

    We report extensive simulations of liquid supercooled states for a simple three-site molecular model, introduced by Lewis and Wahnstrom [Phys. Rev. E >50, 3865 (1994)] to mimic the behavior of ortho-terphenyl. The large system size and the long simulation length allow us to calculate very precisely (in a large q-vector range) self-correlation and collective correlation functions, providing a clean and simple reference model for theoretical descriptions of molecular liquids in supercooled states. The time and wave-vector dependence of the site-site correlation functions are compared (neglecting the molecular constraints) with detailed ideal mode-coupling theory predictions. Except for the wave-vector region where the dynamics are controlled by the center of mass (around 9 nm{sup {minus}1}), the theoretical predictions compare very well with the simulation data.

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

    PubMed

    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. PMID:25768445

  17. METHANE GAS STABILIZES SUPERCOOLED ETHANE DROPLETS IN TITAN'S CLOUDS

    SciTech Connect

    Wang, Chia C.; Lang, E. Kathrin; Signorell, Ruth

    2010-03-20

    Strong evidence for ethane clouds in various regions of Titan's atmosphere has recently been found. Ethane is usually assumed to exist as ice particles in these clouds, although the possible role of liquid and supercooled liquid ethane droplets has been recognized. Here, we report on infrared spectroscopic measurements of ethane aerosols performed in the laboratory under conditions mimicking Titan's lower atmosphere. The results clearly show that liquid ethane droplets are significantly stabilized by methane gas which is ubiquitous in Titan's nitrogen atmosphere-a phenomenon that does not have a counterpart for water droplets in Earth's atmosphere. Our data imply that supercooled ethane droplets are much more abundant in Titan's clouds than previously anticipated. Possibly, these liquid droplets are even more important for cloud processes and the formation of lakes than ethane ice particles.

  18. Behavior of severely supercooled water drops impacting on superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Maitra, Tanmoy; Antonini, Carlo; Tiwari, Manish K.; Mularczyk, Adrian; Imeri, Zulkufli; Schoch, Philippe; Poulikakos, Dimos

    2014-11-01

    Surface icing, commonplace in nature and technology, has broad implications to daily life. To prevent surface icing, superhydrophobic surfaces/coatings with rationally controlled roughness features (both at micro and nano-scale) are considered to be a promising candidate. However, to fabricate/synthesize a high performance icephobic surface or coating, understanding the dynamic interaction between water and the surface during water drop impact in supercooled state is necessary. In this work, we investigate the water/substrate interaction using drop impact experiments down to -17°C. It is found that the resulting increased viscous effect of water at low temperature significantly affects all stages of drop dynamics such as maximum spreading, contact time and meniscus penetration into the superhydrophobic texture. Most interestingly, the viscous effect on the meniscus penetration into roughness feature leads to clear change in the velocity threshold for rebounding to sticking transition by 25% of supercooled drops. Swiss National Science Foundation (SNF) Grant 200021_135479.

  19. Nucleationand surface induced crystallization in supercooled liquid water

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  20. Supercooling effects in Cu-10 wt pct Co alloys solidified at different cooling rates

    NASA Technical Reports Server (NTRS)

    Munitz, A.; Elder-Randall, S. P.; Abbaschian, R.

    1992-01-01

    Electromagnetic levitation and electron beam surface melting were employed to study the effects of supercooling and cooling rate on the solidification of Cu-10 wt pct Co alloys. Two major effects were observed in the supercooled alloys: the nucleation of a metastable copper-rich phase which contains 13 wt pct to 20 wt pct Co in samples supercooled between 105 and 150 K and liquid phase separation which occurs in samples supercooled 150 K or more. The microstructure of the electron beam melted surfaces consisted of very fine spheres which were similar to those of the sample supercooled more than 150 K but with a refined microstructure. The results indicate that a dynamic bulk supercooling of 150 K may exist in the molten pool during the solidification of electron beam melted surfaces.

  1. Study on Ice Formation in Still Supercooled Water with Ice Nucleating Substance

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Takeya, Kengo; Asano, Takaya

    Relating to the problem of supercooling phenomenon for ice storage system, the effect of ice nucleating substances (Xanthan gum, Silver iodide, Copper sulfide, Cholesterole and Ice nucleating bacteria) in still bulk supercooled water was investigated. In the experiment, the test water sample containing the ice nucleating substance was cooled below the equilibrium freezing point temperature in low-temperature room maintained at -40 °C, and its freezing temperature was measured for various mass ratios of ice nucleating substance to water. The supercooling degree for the test water sample decreased with an increase in the mass ratio. It was found that the supercooling degree for the test sample with the insoluble ice nucleating substance was smaller than that for the soluble one. Among test ice nucleating substances, Cholesterole had a pronounced effect on the ice nucleation of supercooled water. However, it was clarified that the supercooling degree for each test sample increased by repeating the process of freezing and melting.

  2. Lack of supercooling evolution related to winter severity in a lizard.

    PubMed

    Michels-Boyce, Madeline; Zani, Peter A

    2015-10-01

    As organisms move into higher latitudes, they may evolve physiological mechanisms to survive in harsher climates. One such mechanism is supercooling, the capacity to survive at subzero temperatures without freezing. While interspecific comparisons reveal greater thermal tolerances at higher latitudes in insects and vertebrates, evidence for intraspecific evolution in supercooling related to latitude is only evident in insects. We measured the supercooling points of lizards from 12 populations reared from hatch in common laboratory conditions to test for evolved differences in supercooling related to winter. Results indicate that winter harshness (depth or length) cannot explain supercooling points regardless of how data are analyzed, which suggests that populations have not evolved greater supercooling capacity. While our results are consistent with the idea that thermal physiology is evolutionarily conserved in vertebrates, we cannot reject several alternatives including the possibility that lizards are able to behaviorally avoid the extreme temperatures that would select for thermal evolution. PMID:26590458

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

    PubMed

    Kühnel, M; Fernández, J M; Tramonto, F; Tejeda, G; Moreno, E; Kalinin, A; Nava, M; Galli, D E; Montero, S; Grisenti, R E

    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 (pH2) or orthodeuterium (oD2) 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 pH2 and oD2 crystal growth rates, similarly to what found in our previous work on supercooled pH2-oD2 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. PMID:26277142

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

    SciTech Connect

    Kühnel, M.; Kalinin, A.; Fernández, J. M.; Tejeda, G.; Moreno, E.; Montero, S.; Tramonto, F.; Galli, D. E.; Nava, M.; Grisenti, R. E.

    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.

  5. Growth of metal oxide nanowires from supercooled liquid nanodroplets.

    SciTech Connect

    Kim, M. H.; Lee, B.; Lee, S.; Larson, C.; Balik, J. M.; Yavuz, C. T.; Seifert, S.; Vajda, S.; Winans, R. E.; Moskovits, M.; Stucky, G. D.; Wodtke, A. M.; Univ. of California at Santa Barbara; Yale Univ.

    2009-12-01

    Nanometer-sized liquid droplets formed at temperatures below the bulk melting point become supercooled as they grow through Ostwald ripening or coalescence and can be exploited to grow nanowires without any catalyst. We used this simple approach to synthesize a number of highly crystalline metal oxide nanowires in a chemical or physical vapor deposition apparatus. Examples of nanowires made in this way include VO{sub 2}, V{sub 2}O{sub 5}, RuO{sub 2}, MoO{sub 2}, MoO{sub 3}, and Fe{sub 3}O{sub 4}, some of which have not been previously reported. Direct evidence of this new mechanism of nanowire growth is found from in situ 2-dimensional GISAXS (grazing incidence small angle X-ray scattering) measurements of VO{sub 2} nanowire growth, which provides quantitative information on the shapes and sizes of growing nanowires as well as direct evidence of the presence of supercooled liquid droplets. We observe dramatic changes in nanowire growth by varying the choice of substrate, reflecting the influence of wetting forces on the supercooled nanodroplet shape and mobility as well as substrate-nanowire lattice matching on the definition of nanowire orientation. Surfaces with defects can also be used to pattern the growth of the nanowires. The simplicity of this synthesis concept suggests it may be rather general in its application.

  6. Double deeply virtual Compton scattering on nucleons and nuclei

    SciTech Connect

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2010-07-01

    In this paper we evaluate the double deeply virtual Compton scattering on nucleons and nuclei in the framework of the color dipole model. Both the effects of quark and the gluon shadowing are taken into account.

  7. VISTA Stares Deeply into the Blue Lagoon

    NASA Astrophysics Data System (ADS)

    2011-01-01

    This new infrared image of the Lagoon Nebula was captured as part of a five-year study of the Milky Way using ESO's VISTA telescope at the Paranal Observatory in Chile. This is a small piece of a much larger image of the region surrounding the nebula, which is, in turn, only one part of a huge survey. Astronomers are currently using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) to scour the Milky Way's central regions for variable objects and map its structure in greater detail than ever before. This huge survey is called VISTA Variables in the Via Lactea (VVV) [1]. The new infrared image presented here was taken as part of this survey. It shows the stellar nursery called the Lagoon Nebula (also known as Messier 8, see eso0936), which lies about 4000-5000 light-years away in the constellation of Sagittarius (the Archer). Infrared observations allow astronomers to peer behind the veil of dust that prevents them from seeing celestial objects in visible light. This is because visible light, which has a wavelength that is about the same size as the dust particles, is strongly scattered, but the longer wavelength infrared light can pass through the dust largely unscathed. VISTA, with its 4.1-metre diameter mirror - the largest survey telescope in the world - is dedicated to surveying large areas of the sky at near-infrared wavelengths deeply and quickly. It is therefore ideally suited to studying star birth. Stars typically form in large molecular clouds of gas and dust, which collapse under their own weight. The Lagoon Nebula, however, is also home to a number of much more compact regions of collapsing gas and dust, called Bok globules [2]. These dark clouds are so dense that, even in the infrared, they can block the starlight from background stars. But the most famous dark feature in the nebula, for which it is named, is the lagoon-shaped dust lane that winds its way through the glowing cloud of gas. Hot, young stars, which give off intense

  8. VISTA Stares Deeply into the Blue Lagoon

    NASA Astrophysics Data System (ADS)

    2011-01-01

    This new infrared image of the Lagoon Nebula was captured as part of a five-year study of the Milky Way using ESO's VISTA telescope at the Paranal Observatory in Chile. This is a small piece of a much larger image of the region surrounding the nebula, which is, in turn, only one part of a huge survey. Astronomers are currently using ESO's Visible and Infrared Survey Telescope for Astronomy (VISTA) to scour the Milky Way's central regions for variable objects and map its structure in greater detail than ever before. This huge survey is called VISTA Variables in the Via Lactea (VVV) [1]. The new infrared image presented here was taken as part of this survey. It shows the stellar nursery called the Lagoon Nebula (also known as Messier 8, see eso0936), which lies about 4000-5000 light-years away in the constellation of Sagittarius (the Archer). Infrared observations allow astronomers to peer behind the veil of dust that prevents them from seeing celestial objects in visible light. This is because visible light, which has a wavelength that is about the same size as the dust particles, is strongly scattered, but the longer wavelength infrared light can pass through the dust largely unscathed. VISTA, with its 4.1-metre diameter mirror - the largest survey telescope in the world - is dedicated to surveying large areas of the sky at near-infrared wavelengths deeply and quickly. It is therefore ideally suited to studying star birth. Stars typically form in large molecular clouds of gas and dust, which collapse under their own weight. The Lagoon Nebula, however, is also home to a number of much more compact regions of collapsing gas and dust, called Bok globules [2]. These dark clouds are so dense that, even in the infrared, they can block the starlight from background stars. But the most famous dark feature in the nebula, for which it is named, is the lagoon-shaped dust lane that winds its way through the glowing cloud of gas. Hot, young stars, which give off intense

  9. Change of supercooling capability in solutions containing different kinds of ice nucleators by flavonol glycosides from deep supercooling xylem parenchyma cells in trees.

    PubMed

    Kuwabara, Chikako; Kasuga, Jun; Wang, Donghui; Fukushi, Yukiharu; Arakawa, Keita; Koyama, Toshie; Inada, Takaaki; Fujikawa, Seizo

    2011-12-01

    Deep supercooling xylem parenchyma cells (XPCs) in Katsura tree contain flavonol glycosides with high supercooling-facilitating capability in solutions containing the ice nucleation bacterium (INB) Erwinia ananas, which is thought to have an important role in deep supercooling of XPCs. The present study, in order to further clarify the roles of these flavonol glycosides in deep supercooling of XPCs, the effects of these supercooling-facilitating (anti-ice nucleating) flavonol glycosides, kaempferol 3-O-β-D-glucopyranoside (K3Glc), kaempferol 7-O-β-D-glucopyranoside (K7Glc) and quercetin 3-O-β-D-glucopyranoside (Q3Glc), in buffered Milli-Q water (BMQW) containing different kinds of ice nucleators, including INB Xanthomonas campestris, silver iodide and phloroglucinol, were examined by a droplet freezing assay. The results showed that all of the flavonol glycosides promoted supercooling in all solutions containing different kinds of ice nucleators, although the magnitudes of supercooling capability of each flavonol glycoside changed in solutions containing different kinds of ice nucleators. On the other hand, these flavonol glycosides exhibited complicated nucleating reactions in BMQW, which did not contain identified ice nucleators but contained only unidentified airborne impurities. Q3Glc exhibited both supercooling-facilitating and ice nucleating capabilities depending on the concentrations in such water. Both K3Glc and K7Glc exhibited only ice nucleation capability in such water. It was also shown by an emulsion freezing assay in BMQW that K3Glc and Q3Glc had no effect on homogeneous ice nucleation temperature, whereas K7Glc increased ice nucleation temperature. The results indicated that each flavonol glycoside affected ice nucleation by very complicated and varied reactions. More studies are necessary to determine the exact roles of these flavonol glycosides in deep supercooling of XPCs in which unidentified heterogeneous ice nucleators may exist. PMID

  10. Why is there no clear glass transition of confined water?

    NASA Astrophysics Data System (ADS)

    Swenson, Jan; Elamin, Khalid; Jansson, Helén; Kittaka, Shigeharu

    2013-10-01

    To overcome the problem of crystallization of supercooled bulk water and water rich solutions we have studied water-glycerol mixtures confined in 21 Å pores of the silica matrix MCM-41 C10. The results from the differential scanning calorimetry (DSC) measurements shows an almost concentration independent glass transition temperature, Tg, at about 176 K for water concentrations up to 80 wt%, suggesting that the confined water has no influence on Tg in this concentration range. Rather, the findings indicate that the water molecules in the solutions have a stronger preference to coordinate to the hydroxyl surface groups than the glycerol molecules, which results in a micro-phase separation of the two liquids. The water phase does not give any sign of a Tg and therefore the observed Tg should be associated with the glass transition of the glycerol phase. Finally, we discuss why the confined water does not exhibit any clear calorimetric Tg.

  11. Suppression of phase transitions in a confined rodlike liquid crystal.

    PubMed

    Grigoriadis, Christos; Duran, Hatice; Steinhart, Martin; Kappl, Michael; Butt, Hans-Jürgen; Floudas, George

    2011-11-22

    The nematic-to-isotropic, crystal-to-nematic, and supercooled liquid-to-glass temperatures are studied in the liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) confined in self-ordered nanoporous alumina. The nematic-to-isotropic and the crystal-to-nematic transition temperatures are reduced linearly with the inverse pore diameter. The finding that the crystalline phase is completely suppressed in pores having diameters of 35 nm and below yields an estimate of the critical nucleus size. The liquid-to-glass temperature is reduced in confinement as anticipated by the model of rotational diffusion within a cavity. These results provide the pertinent phase diagram for a confined liquid crystal and are of technological relevance for the design of liquid crystal-based devices with tunable optical, thermal, and dielectric properties. PMID:21974835

  12. Arrest as a General Property of the Supercooled Liquid State.

    PubMed

    Sluyters, Jan H; Sluyters-Rehbach, Margaretha

    2016-04-21

    Owing to the universal presence of intermolecular interactions, it has to be expected that at some well-defined lower temperature a liquid loses its dynamic properties like fluidity and self-diffusion. As a sequel to two earlier papers on the discovery of such an arrest temperature T0 for supercooled water at 243 K, where also the coexisting vapor pressure was found to become zero, in this paper a further study is undertaken of the behavior of a selection of other liquids. At first, two simple equations of state (van der Waals and virial) are shown in principle to predict a zero vapor pressure at a finite temperature. The interaction parameters B (second virial coefficient) and μJT (Joule-Thomson coefficient) of the vapor are found to become virtually infinite at a temperature T0,B, with a value equal or close to the T0 derived from the liquid properties. Just as earlier found for water, the latter is obtained by extrapolation of several available dynamic and equilibrium data, which should produce an intersection with the temperature axis at the same T0 value. With the exception of molten salts and liquid pure metals, this condition appears to be fulfilled quite accurately. Thus, the temperature of arrest is a general phenomenon for supercooled liquids. As an illustration, it is shown how the PVT diagram of carbon dioxide can be extended into the supercooled temperature region. It is argued that T0 is the temperature below which the Boltzmann energy, kT, is lower than the minimal energy needed for a molecule to break the interactions with its surrounding molecules. We propose to name this minimal energy, kT0, the multimolecular potential of the liquid object. The relationship of the liquid multimolecular potential with the pair potential, ε, of the molecular species is established for various examples and appears to be a proportionality with ε ≈ 2kT0. PMID:27070201

  13. A Database of Supercooled Large Droplet Ice Accretions

    NASA Technical Reports Server (NTRS)

    VanZante, Judith Foss

    2007-01-01

    A unique, publicly available database regarding supercooled large droplet ice accretions has been developed in NASA Glenn's Icing Research Tunnel. Identical cloud and flight conditions were generated for five different airfoil models. The models chosen represent a variety of aircraft types from the horizontal stabilizer of a large trans-port aircraft to the wings of regional, business, and general aviation aircraft. In addition to the standard documentation methods of 2D ice shape tracing and imagery, ice mass measurements were also taken. This database will also be used to validate and verify the extension of the ice accretion code, LEWICE, into the SLD realm.

  14. A Database of Supercooled Large Droplet Ice Accretions [Supplement

    NASA Technical Reports Server (NTRS)

    VanZante, Judith Foss

    2007-01-01

    A unique, publicly available database regarding supercooled large droplet (SLD) ice accretions has been developed in NASA Glenn's Icing Research Tunnel. Identical cloud and flight conditions were generated for five different airfoil models. The models chosen represent a variety of aircraft types from the horizontal stabilizer of a large transport aircraft to the wings of regional, business, and general aviation aircraft. In addition to the standard documentation methods of 2D ice shape tracing and imagery, ice mass measurements were also taken. This database will also be used to validate and verify the extension of the ice accretion code, LEWICE, into the SLD realm.

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  16. Theory of Activated Relaxation in Nanoscale Confined Liquids

    NASA Astrophysics Data System (ADS)

    Mirigian, Stephen; Schweizer, Kenneth

    2014-03-01

    We extend the recently developed Elastically Cooperative Nonlinear Langevin Equation(ECNLE) theory of activated relaxation in supercooled liquids to treat the case of geometrically confined liquids. Generically, confinement of supercooled liquids leads to a speeding up of the dynamics(with a consequent depression of the glass transition temperature) extending on the order of tens of molecular diameters away from a free surface. At present, this behavior is not theoretically well understood. Our theory interprets the speed up in dynamics in terms of two coupled effects. First, a direct surface effect, extending two to three molecular diameters from a free surface, and related to a local rearrangement of molecules with a single cage. The second is a longer ranged ``confinement'' effect, extending tens of molecular diameters from a free surface and related to the long range elastic penalty necessary for a local rearrangement. The theory allows for the calculation of relaxation time and Tg profiles within a given geometry and first principles calculations of relevant length scales. Comparison to both dynamic and pseudo-thermodynamic measurements shows reasonable agreement to experiment with no adjustable parameters.

  17. Xylem Development in Prunus Flower Buds and the Relationship to Deep Supercooling

    PubMed Central

    Ashworth, Edward N.

    1984-01-01

    Xylem development in eight Prunus species was examined and the relationship to deep supercooling assessed. Dormant buds of six species, P. armeniaca, P. avium, P. cerasus, P. persica, P. salicina, and P. sargentii deep supercooled. Xylem vessel elements were not observed within the dormant floral primordia of these species. Instead, discrete bundles containing procambial cells were observed. Vascular differentiation resumed and xylem continuity was established during the time that the capacity to deep supercool was lost. In P. serotina and P. virginiana, two species which do not supercool, xylem vessels ran the length of the inflorescence and presumably provided a conduit for the spread of ice into the bud. The results support the hypothesis that the lack of xylem continuity is an important feature of buds which deep supercool. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:16663523

  18. Structure and production of deeply bound pionic atoms

    SciTech Connect

    Toki, H. )

    1991-04-10

    We study the structure and production of deeply bound pionic atoms in heavy nuclei, which are found quasi-stable due to the repulsive pion-nucleus optical potential and the attractive Coulomb potential. The bound pion forms a pionic halo just outside of nucleus. We discuss then the use of pion transfer reactions such as (n,p) and (d, {sup 2}He) to form these states. In addition, we study other processes such as (n,d) and (d, {sup 3}He) and the use of the inverse kinematics for formation of deeply bound pionic atoms.

  19. Magnetization Processes During FM Transitions of Supercooled Er Films

    NASA Astrophysics Data System (ADS)

    Durfee, C. S.; Flynn, C. P.

    2000-03-01

    FM transitions are generally accompanied by dimensional changes of the crystal lattice. In magnetic films, the in-plane dimensional changes are inhibited by clamping to the substrate, creating a rich variety of phenomena (e.g. supercooling, dislocation formation and motion, bowing of dislocations, and altered magnetization processes), which can be directly observed with x-rays. Here we characterize the magnetization processes exhibited by unstrained Er films. Below the Curie temperature, the film exhibits supercooling, remaining in a metastable non-FM state and only relaxing to the FM state when a magnetic field is applied. This occurs by two distinct processes. The first process, which broadens the x-ray line shape, is nucleation and growth of FM domains. The second, which produces no line broadening, is isotropic magnetization of the entire film. Once magnetized, the film remains in the FM state until the temperature is raised several degrees above the Curie temperature, at which point the film relaxes to the non-FM state via one of these two paths. This process depends on the temperature when the field is removed.

  20. Translational dynamics of antifreeze glycoprotein in supercooled water.

    PubMed

    Krishnan, V V; Fink, William H; Feeney, Robert E; Yeh, Yin

    2004-08-01

    Structure and dynamics of biomolecules in supercooled water assume a particular and distinct importance in the case of antifreeze glycoproteins (AFGPs), which function at sub-zero temperatures. To investigate whether any large-scale structural digressions in the supercooled state are correlated to the function of AFGPs, self-diffusion behavior of the AFGP8, the smallest AFGP is monitored as a function of temperature from 243 to 303 K using nuclear magnetic resonance (NMR) spectroscopy. The experimental results are compared with the hydrodynamic calculations using the viscosity of water at the same temperature range. In order to evaluate results on AFGP8, the smallest AFGP, constituting approximately two-thirds of the total AFGP fraction in fish blood serum, similar experimental and computational calculations were also performed on a set of globular proteins. These results show that even though the general trend of translational dynamics of AFGP is similar to that of the other globular proteins, AFGP8 appears to be more hydrated (approximately 30% increase in the bead radius) than the others over the temperature range studied. These results also suggest that local conformational changes such as segmental librations or hydrogen bond dynamics that are closer to the protein surface are more likely the determining dynamic factors for the function of AFGPs rather than any large-scale structural rearrangements. PMID:15228958

  1. Tensorial analysis of Eshelby stresses in 3D supercooled liquids

    NASA Astrophysics Data System (ADS)

    Lemaître, Anaël

    2015-10-01

    It was recently proposed that the local rearrangements governing relaxation in supercooled liquids impress on the liquid medium long-ranged (Eshelby) stress fluctuations that accumulate over time. From this viewpoint, events must be characterized by elastic dipoles, which are second order tensors, and Eshelby fields are expected to show up in stress and stress increment correlations, which are fourth order tensor fields. We construct here an analytical framework that permits analyzing such tensorial correlations in isotropic media in view of accessing Eshelby fields. Two spherical bases are introduced, which correspond to Cartesian and spherical coordinates for tensors. We show how they can be used to decompose stress correlations and thus test such properties as isotropy and power-law scalings. Eshelby fields and the predicted stress correlations in an infinite medium are shown to belong to an algebra that can conveniently be described using the spherical tensor bases. Using this formalism, we demonstrate that the inherent stress field of 3D supercooled liquids is power law correlated and carries the signature of Eshelby fields, thus supporting the idea that relaxation events give rise to Eshelby stresses that accumulate over time.

  2. Liquid-liquid critical point in supercooled silicon

    NASA Astrophysics Data System (ADS)

    Vasisht, Vishwas V.; Saw, Shibu; Sastry, Srikanth

    2011-07-01

    A novel liquid-liquid phase transition has been investigated for a wide variety of pure substances, including water, silica and silicon. From computer simulations using the Stillinger-Weber (SW) classical empirical potential, Sastry and Angell demonstrated a first order liquid-liquid transition in supercooled silicon at zero pressure, supported by subsequent experimental and simulation studies. Whether the line of such first order transitions will terminate at a critical point, expected to lie at negative pressures, is presently a matter of debate. Here we report evidence for a liquid-liquid critical point at negative pressures, from computer simulations using the SW potential. We identify Tc~1,120+/-12K, Pc~-0.60+/-0.15GPa as the critical temperature and pressure. We construct the phase diagram of supercooled silicon, which reveals the interconnection between thermodynamic anomalies and the phase behaviour of the system as suggested in previous works. We also observe a strong relationship between local geometry (quantified by the coordination number) and diffusivity, both of which change dramatically with decreasing temperature and pressure.

  3. Tensorial analysis of Eshelby stresses in 3D supercooled liquids.

    PubMed

    Lemaître, Anaël

    2015-10-28

    It was recently proposed that the local rearrangements governing relaxation in supercooled liquids impress on the liquid medium long-ranged (Eshelby) stress fluctuations that accumulate over time. From this viewpoint, events must be characterized by elastic dipoles, which are second order tensors, and Eshelby fields are expected to show up in stress and stress increment correlations, which are fourth order tensor fields. We construct here an analytical framework that permits analyzing such tensorial correlations in isotropic media in view of accessing Eshelby fields. Two spherical bases are introduced, which correspond to Cartesian and spherical coordinates for tensors. We show how they can be used to decompose stress correlations and thus test such properties as isotropy and power-law scalings. Eshelby fields and the predicted stress correlations in an infinite medium are shown to belong to an algebra that can conveniently be described using the spherical tensor bases. Using this formalism, we demonstrate that the inherent stress field of 3D supercooled liquids is power law correlated and carries the signature of Eshelby fields, thus supporting the idea that relaxation events give rise to Eshelby stresses that accumulate over time. PMID:26520535

  4. Probing Cooperative Motion in Super-Cooled Colloidal Suspensions

    NASA Astrophysics Data System (ADS)

    Sarangapani, Prasad; Zhu, Y. Elaine

    2008-03-01

    The physics of the glass transition remains inadequately understood despite its broad technological relevance. The anomalous divergence of viscosity without apparent structural change as a liquid is cooled has been attributed to the existence of growing dynamic length scales of ``cooperatively rearranging regions'' (CRR). In this work, we use ultra-fast fluorescence correlation spectroscopy (FCS) combined with high-speed imaging to determine the CRR sizes by measuring single-particle dynamics of tracer nano-particle embedded in super-cooled ``hard-sphere'' colloidal suspensions. Fluorescent poly-(methyl methacrylate) (PMMA) tracer particles of radii ranging from r=0.1-0.4 μm, mixed with plain PMMA particles of radius, r=0.6 μm and bulk volume fraction, φ = 0.38-0.58, serve as excellent probes for changes in the energy barrier landscape of the suspensions of increasing volume fraction and are sensitive to the creation and annihilation of icosahedral order in metastable colloidal fluids. We also find that the correlation length, determined by fluctuation-dissipation relations from the measured auto-correlation functions, shows a dramatic increase in the super-cooled regime until it diverges at φ=0.58.

  5. Supercooling preservation and transplantation of the rat liver.

    PubMed

    Bruinsma, Bote G; Berendsen, Tim A; Izamis, Maria-Louisa; Yeh, Heidi; Yarmush, Martin L; Uygun, Korkut

    2015-03-01

    The current standard for liver preservation involves cooling of the organ on ice (0-4 °C). Although it is successful for shorter durations, this method of preservation does not allow long-term storage of the liver. The gradual loss of hepatic viability during preservation puts pressure on organ sharing and allocation, may limit the use of suboptimal grafts and necessitates rushed transplantation to achieve desirable post-transplantation outcomes. In an attempt to improve and prolong liver viability during storage, alternative preservation methods are under investigation. For instance, ex vivo machine perfusion systems aim to sustain and even improve viability by supporting hepatic function at warm temperatures, rather than simply slowing down deterioration by cooling. Here we describe a novel subzero preservation technique that combines ex vivo machine perfusion with cryoprotectants to facilitate long-term supercooled preservation. The technique improves the preservation of rat livers to prolong storage times as much as threefold, which is validated by successful long-term recipient survival after orthotopic transplantation. This protocol describes how to load rat livers with cryoprotectants to prevent both intracellular and extracellular ice formation and to protect against hypothermic injury. Cryoprotectants are loaded ex vivo using subnormothermic machine perfusion (SNMP), after which livers can be cooled to -6 °C without freezing and kept viable for up to 96 h. Cooling to a supercooled state is controlled, followed by 3 h of SNMP recovery and orthotopic liver transplantation. PMID:25692985

  6. Measurement of Deeply Virtual Compton Scattering at HERMES

    SciTech Connect

    Kopytin, M.

    2005-10-06

    The measurement of azimuthal cross section asymmetries from deeply virtual Compton scattering on the proton and deuteron at HERMES is discussed. In particular results on the longitudinal target spin asymmetry as a function of the azimuthal angle and the Mandelstam t are given. The t-dependence of the asymmetry is compared with calculations based on generalized parton distribution models.

  7. New JLab/Hall A Deeply Virtual Compton Scattering results

    SciTech Connect

    Defurne, Maxime

    2015-08-01

    New data points for unpolarized Deeply Virtual Compton Scattering cross sections have been extracted from the E00-110 experiment at Q2=1.9 GeV2 effectively doubling the statistics available in the valence region. A careful study of systematic uncertainties has been performed.

  8. Shear-Triggered Crystallization and Light Emission of a Thermally Stable Organic Supercooled Liquid.

    PubMed

    Chung, Kyeongwoon; Kwon, Min Sang; Leung, Brendan M; Wong-Foy, Antek G; Kim, Min Su; Kim, Jeongyong; Takayama, Shuichi; Gierschner, Johannes; Matzger, Adam J; Kim, Jinsang

    2015-05-27

    Thermodynamics drive crystalline organic molecules to be crystallized at temperatures below their melting point. Even though molecules can form supercooled liquids by rapid cooling, crystalline organic materials readily undergo a phase transformation to an energetically favorable crystalline phase upon subsequent heat treatment. Opposite to this general observation, here, we report molecular design of thermally stable supercooled liquid of diketopyrrolopyrrole (DPP) derivatives and their intriguing shear-triggered crystallization with dramatic optical property changes. Molten DPP8, one of the DPP derivatives, remains as stable supercooled liquid without crystallization through subsequent thermal cycles. More interestingly, under shear conditions, this supercooled liquid DPP8 transforms to its crystal phase accompanied by a 25-fold increase in photoluminescence (PL) quantum efficiency and a color change. By systematic investigation on supercooled liquid formation of crystalline DPP derivatives and their correlation with chemical structures, we reveal that the origin of this thermally stable supercooled liquid is a subtle force balance between aromatic interactions among the core units and van der Waals interactions among the aliphatic side chains acting in opposite directions. Moreover, by applying shear force to a supercooled liquid DPP8 film at different temperatures, we demonstrated direct writing of fluorescent patterns and propagating fluorescence amplification, respectively. Shear-triggered crystallization of DPP8 is further achieved even by living cell attachment and spreading, demonstrating the high sensitivity of the shear-triggered crystallization which is about 6 orders of magnitude more sensitive than typical mechanochromism observed in organic materials. PMID:27162955

  9. Shear-Triggered Crystallization and Light Emission of a Thermally Stable Organic Supercooled Liquid

    PubMed Central

    2015-01-01

    Thermodynamics drive crystalline organic molecules to be crystallized at temperatures below their melting point. Even though molecules can form supercooled liquids by rapid cooling, crystalline organic materials readily undergo a phase transformation to an energetically favorable crystalline phase upon subsequent heat treatment. Opposite to this general observation, here, we report molecular design of thermally stable supercooled liquid of diketopyrrolopyrrole (DPP) derivatives and their intriguing shear-triggered crystallization with dramatic optical property changes. Molten DPP8, one of the DPP derivatives, remains as stable supercooled liquid without crystallization through subsequent thermal cycles. More interestingly, under shear conditions, this supercooled liquid DPP8 transforms to its crystal phase accompanied by a 25-fold increase in photoluminescence (PL) quantum efficiency and a color change. By systematic investigation on supercooled liquid formation of crystalline DPP derivatives and their correlation with chemical structures, we reveal that the origin of this thermally stable supercooled liquid is a subtle force balance between aromatic interactions among the core units and van der Waals interactions among the aliphatic side chains acting in opposite directions. Moreover, by applying shear force to a supercooled liquid DPP8 film at different temperatures, we demonstrated direct writing of fluorescent patterns and propagating fluorescence amplification, respectively. Shear-triggered crystallization of DPP8 is further achieved even by living cell attachment and spreading, demonstrating the high sensitivity of the shear-triggered crystallization which is about 6 orders of magnitude more sensitive than typical mechanochromism observed in organic materials. PMID:27162955

  10. Supercooling of aqueous NaCl and KCl solutions under acoustic levitation.

    PubMed

    Lü, Y J; Wei, B

    2006-10-14

    The supercooling capability of aqueous NaCl and KCl solutions is investigated at containerless state by using acoustic levitation method. The supercooling of water is obviously enhanced by the alkali metal ions and increases linearly with the augmentation of concentrations. Furthermore, the supercooling depends on the nature of ions and is 2-3 K larger for NaCl solution than that for KCl solution in the present concentration range: Molecular dynamics simulations are performed to reveal the intrinsic correlation between supercoolability and microstructure. The translational and orientational order parameters are applied to quantitatively demonstrate the effect of ionic concentration on the hydrogen-bond network and ice melting point. The disrupted hydrogen-bond structure determines essentially the concentration dependence of supercooling. On the other hand, the introduced acoustic pressure suppresses the increase of supercooling by promoting the growth and coalescence of microbubbles, the effective nucleation catalysts, in water. However, the dissolved ions can weaken this effect, and moreover the degree varies with the ion type. This results in the different supercoolability for NaCl and KCl solutions under the acoustic levitation conditions. PMID:17042605

  11. 2H NMR studies of supercooled and glassy aspirin

    NASA Astrophysics Data System (ADS)

    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.

  12. Correlation between supercooled liquid relaxation and glass Poisson's ratio.

    PubMed

    Sun, Qijing; Hu, Lina; Zhou, Chao; Zheng, Haijiao; Yue, Yuanzheng

    2015-10-28

    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 lies in the heredity of the structural heterogeneity from liquid to glass. This work gives insights into both the microscopic mechanism of glass deformation through the SL dynamics and the complex structural evolution during liquid-glass transition. PMID:26520524

  13. Correlation between supercooled liquid relaxation and glass Poisson's ratio

    NASA Astrophysics Data System (ADS)

    Sun, Qijing; Hu, Lina; Zhou, Chao; Zheng, Haijiao; Yue, Yuanzheng

    2015-10-01

    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 lies in the heredity of the structural heterogeneity from liquid to glass. This work gives insights into both the microscopic mechanism of glass deformation through the SL dynamics and the complex structural evolution during liquid-glass transition.

  14. Nuclear magnetic resonance studies of supercooled aqueous electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Lang, E. W.; Bradl, S.; Fink, W.; Radkowitsch, H.; Girlich, D.

    1990-12-01

    The dynamic properties of water molecules coordinated to simple ions (alkali and alkali-earth halides) and hydrophobic ions (tetraalkylammonium (TAA) halides) in supercooled solutions have been investigated with NMR. The study of spin-lattice relaxation rates and self-diffusion coefficients as functions of temperature, pressure Larmor frequency and concentration reveals characteristic features of molecular motions close to the low-temperature limit of the metastable phase (percolation transition and glass transition) and provides certain details of the local arrangement of water molecules in the coordination sphere of these ions. The intramolecular flexibility of the alkyl chains of the hydrated TAA cations has been investigated also. The dynamics of the methyl group reorientation provide a sensitive probe of structural differences in these solutions.

  15. Supercooling and phase coexistence in cosmological phase transitions

    SciTech Connect

    Megevand, Ariel; Sanchez, Alejandro D.

    2008-03-15

    Cosmological phase transitions are predicted by particle physics models, and have a variety of important cosmological consequences, which depend strongly on the dynamics of the transition. In this work we investigate in detail the general features of the development of a first-order phase transition. We find thermodynamical constraints on some quantities that determine the dynamics, namely, the latent heat, the radiation energy density, and the false-vacuum energy density. Using a simple model with a Higgs field, we study numerically the amount and duration of supercooling and the subsequent reheating and phase coexistence. We analyze the dependence of the dynamics on the different parameters of the model, namely, the energy scale, the number of degrees of freedom, and the couplings of the scalar field with bosons and fermions. We also inspect the implications for the cosmological outcomes of the phase transition.

  16. The microscopic pathway to crystallization in supercooled liquids

    PubMed Central

    Russo, John; Tanaka, Hajime

    2012-01-01

    Despite its fundamental and technological importance, a microscopic understanding of the crystallization process is still elusive. By computer simulations of the hard-sphere model we reveal the mechanism by which thermal fluctuations drive the transition from the supercooled liquid state to the crystal state. In particular we show that fluctuations in bond orientational order trigger the nucleation process, contrary to the common belief that the transition is initiated by density fluctuations. Moreover, the analysis of bond orientational fluctuations shows that these not only act as seeds of the nucleation process, but also i) determine the particular polymorph which is to be nucleated from them and ii) at high density favour the formation of fivefold structures which can frustrate the formation of crystals. These results can shed new light on our understanding of the relationship between crystallization and vitrification. PMID:22792437

  17. Ultraslow dielectric relaxation process in supercooled polyhydric alcohols

    NASA Astrophysics Data System (ADS)

    Yomogida, Yoshiki; Minoguchi, Ayumi; Nozaki, Ryusuke

    2006-04-01

    Complex permittivity was obtained on glycerol, xylitol, sorbitol and sorbitol-xylitol mixtures in the supercooled liquid state in the frequency range between 10μHz and 500MHz at temperatures near and above the glass transition temperature. For all the materials, a dielectric relaxation process was observed in addition to the well-known structural α and Johari-Goldstein β relaxation process [G. P. Johari and M. Goldstein, J. Chem. Phys. 53, 2372 (1970)]. The relaxation time for the new process is always larger than that for the α process. The relaxation time shows non-Arrhenius temperature dependence with correlation to the behavior of the α process and it depends on the molecular size systematically. The dielectric relaxation strength for the new process shows the effect of thermal history and decreases exponentially with time at a constant temperature. It can be considered that a nonequilibrium dynamics causes the new process.

  18. Experimental Values of the Surface Tension of Supercooled Water

    NASA Technical Reports Server (NTRS)

    Hacker, P. T.

    1951-01-01

    The results of surface-tension measurements for supercooled water are presented. A total of 702 individual measurements of surface tension of triple-distilled water were made in the temperature range, 27 to -22.2 C, with 404 of these measurements at temperatures below 0 C. The increase in magnitude of surface tension with decreasing temperature, as indicated by measurements above 0 C, continues to -22.2 C. The inflection point in the surface-tension - temperature relation in the vicinity of 0 C, as indicated by the International Critical Table values for temperatures down to -8 C, is substantiated by the measurements in the temperature range, 0 to -22.2 C. The surface tension increases at approximately a linear rate from a value of 76.96+/-0.06 dynes per centimeter at -8 C to 79.67+/-0.06 dynes per centimeter at -22.2 C.

  19. Anomalies in bulk supercooled water at negative pressure

    PubMed Central

    Pallares, Gaël; El Mekki Azouzi, Mouna; González, Miguel A.; Aragones, Juan L.; Abascal, José L. F.; Valeriani, Chantal; Caupin, Frédéric

    2014-01-01

    Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144–6154], or emanate from a critical point terminating a liquid–liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727–737]. At positive pressure, the LMκT has escaped observation because it lies in the “no man’s land” beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man’s land at negative pressure. PMID:24843177

  20. Anomalies in bulk supercooled water at negative pressure.

    PubMed

    Pallares, Gaël; El Mekki Azouzi, Mouna; González, Miguel A; Aragones, Juan L; Abascal, José L F; Valeriani, Chantal; Caupin, Frédéric

    2014-06-01

    Water anomalies still defy explanation. In the supercooled liquid, many quantities, for example heat capacity and isothermal compressibility κT, show a large increase. The question arises if these quantities diverge, or if they go through a maximum. The answer is key to our understanding of water anomalies. However, it has remained elusive in experiments because crystallization always occurred before any extremum is reached. Here we report measurements of the sound velocity of water in a scarcely explored region of the phase diagram, where water is both supercooled and at negative pressure. We find several anomalies: maxima in the adiabatic compressibility and nonmonotonic density dependence of the sound velocity, in contrast with a standard extrapolation of the equation of state. This is reminiscent of the behavior of supercritical fluids. To support this interpretation, we have performed simulations with the 2005 revision of the transferable interaction potential with four points. Simulations and experiments are in near-quantitative agreement, suggesting the existence of a line of maxima in κT (LMκT). This LMκT could either be the thermodynamic consequence of the line of density maxima of water [Sastry S, Debenedetti PG, Sciortino F, Stanley HE (1996) Phys Rev E 53:6144-6154], or emanate from a critical point terminating a liquid-liquid transition [Sciortino F, Poole PH, Essmann U, Stanley HE (1997) Phys Rev E 55:727-737]. At positive pressure, the LMκT has escaped observation because it lies in the "no man's land" beyond the homogeneous crystallization line. We propose that the LMκT emerges from the no man's land at negative pressure. PMID:24843177

  1. Intermolecular vibrations and fast relaxations in supercooled ionic liquids

    NASA Astrophysics Data System (ADS)

    Ribeiro, Mauro C. C.

    2011-06-01

    Short-time dynamics of ionic liquids has been investigated by low-frequency Raman spectroscopy (4 < ω < 100 cm-1) within the supercooled liquid range. Raman spectra are reported for ionic liquids with the same anion, bis(trifluoromethylsulfonyl)imide, and different cations: 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-1-methylpiperidinium, trimethylbutylammonium, and tributylmethylammonium. It is shown that low-frequency Raman spectroscopy provides similar results as optical Kerr effect (OKE) spectroscopy, which has been used to study intermolecular vibrations in ionic liquids. The comparison of ionic liquids containing aromatic and non-aromatic cations identifies the characteristic feature in Raman spectra usually assigned to librational motion of the imidazolium ring. The strength of the fast relaxations (quasi-elastic scattering, QES) and the intermolecular vibrational contribution (boson peak) of ionic liquids with non-aromatic cations are significantly lower than imidazolium ionic liquids. A correlation length assigned to the boson peak vibrations was estimated from the frequency of the maximum of the boson peak and experimental data of sound velocity. The correlation length related to the boson peak (˜19 Å) does not change with the length of the alkyl chain in imidazolium cations, in contrast to the position of the first-sharp diffraction peak observed in neutron and X-ray scattering measurements of ionic liquids. The rate of change of the QES intensity in the supercooled liquid range is compared with data of excess entropy, free volume, and mean-squared displacement recently reported for ionic liquids. The temperature dependence of the QES intensity in ionic liquids illustrates relationships between short-time dynamics and long-time structural relaxation that have been proposed for glass-forming liquids.

  2. Dynamics of supercooled water in highly compacted clays studied by neutron scattering

    NASA Astrophysics Data System (ADS)

    González Sánchez, Fátima; Jurányi, Fanni; Gimmi, Thomas; Van Loon, Luc; Seydel, Tilo; Unruh, Tobias

    2008-10-01

    The freezing behavior of water confined in compacted charged and uncharged clays (montmorillonite in Na- and Ca-forms, illite in Na- and Ca-forms, kaolinite and pyrophyllite) was investigated by neutron scattering. Firstly, the amount of frozen (immobile) water was measured as a function of temperature at the IN16 backscattering spectrometer, Institute Laue-Langevin (ILL). Water in uncharged, partly hydrophobic (kaolinite) and fully hydrophobic (pyrophyllite) clays exhibited a similar freezing and melting behavior to that of bulk water. In contrast, water in charged clays which are hydrophilic could be significantly supercooled. To observe the water dynamics in these clays, further experiments were performed using quasielastic neutron scattering. At temperatures of 250, 260 and 270 K the diffusive motion of water could still be observed, but with a strong reduction in the water mobility as compared with the values obtained above 273 K. The diffusion coefficients followed a non-Arrhenius temperature dependence well described by the Vogel-Fulcher-Tammann and the fractional power relations. The fits revealed that Na- and Ca-montmorillonite and Ca-illite have similar Vogel-Fulcher-Tammann temperatures (TVFT, often referred to as the glass transition temperature) of ~120 K and similar temperatures at which the water undergoes the 'strong-fragile' transition, Ts~210 K. On the other hand, Na-illite had significantly larger values of TVFT~180 K and Ts~240 K. Surprisingly, Ca-illite has a similar freezing behavior of water to that of montmorillonites, even though it has a rather different structure. We attribute this to the stronger hydration of Ca ions as compared with the Na ions occurring in the illite clays.

  3. Longitudinal target-spin asymmetries for deeply virtual compton scattering.

    PubMed

    Seder, E; Biselli, A; Pisano, S; Niccolai, S; Smith, G D; Joo, K; Adhikari, K; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Avakian, H; Battaglieri, M; Bedlinskiy, I; Bono, J; Boiarinov, S; Bosted, P; Briscoe, W; Brock, J; Brooks, W K; Bültmann, S; Burkert, V D; Carman, D S; Carlin, C; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Contalbrigo, M; Crabb, D; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Fradi, A; Garillon, B; Garçon, M; Gevorgyan, N; Ghandilyan, Y; Giovanetti, K L; Girod, F X; Goetz, J T; Gohn, W; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hirlinger Saylor, N; Holtrop, M; Hughes, S M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joosten, S; Keith, C D; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuhn, S E; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Meekins, D G; Mineeva, T; Mirazita, M; Mokeev, V; Montgomery, R; Moody, C I; Moutarde, H; Movsisyan, A; Munoz Camacho, C; Nadel-Turonski, P; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardo, L L; Park, K; Park, S; Pasyuk, E; Peng, P; Phelps, W; Pogorelko, O; Price, J W; Prok, Y; Protopopescu, D; Puckett, A J R; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Senderovich, I; Simonyan, A; Skorodumina, I; Sokhan, D; Sparveris, N; Stepanyan, S; Stoler, P; Strakovsky, I I; Strauch, S; Sytnik, V; Taiuti, M; Tang, W; Tian, Y; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zonta, I

    2015-01-23

    A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep→e^{'}p^{'}γ events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ϕ, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions. PMID:25658994

  4. Longitudinal target-spin asymmetries for deeply virtual Compton scattering

    SciTech Connect

    Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Battaglieri, M.; Bedlinskiy, I.; Bono, J.; Boiarinov, S.; Bosted, P.; Briscoe, W.; Brock, J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Carlin, C.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crabb, D.; Crede, V.; D’Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hirlinger Saylor, N.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joosten, S.; Keith, C. D.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L. L.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, W.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Senderovich, I.; Simonyan, A.; Skorodumina, I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tian, Y.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.

    2015-01-22

    A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and Φ, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.

  5. Longitudinal target-spin asymmetries for deeply virtual Compton scattering

    DOE PAGESBeta

    Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; et al

    2015-01-22

    A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6-GeV electron beam, a longitudinally polarized proton target and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep → e'p'y events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2, xB, t and Φ, for 166 four-dimensional bins. In the framework of Generalized Parton Distributions (GPDs), at leading twist the t dependence of these asymmetries provides insight on the spatial distribution of the axialmore » charge of the proton, which appears to be concentrated in its center. In conclusion, these results bring important and necessary constraints for the existing parametrizations of chiral-even GPDs.« less

  6. Removal of Deeply Impacted Mandibular Molars by Sagittal Split Osteotomy

    PubMed Central

    Isler, Sabri Cemil

    2016-01-01

    Mandibular third molars are the most common impacted teeth. Mandibular first and second molars do not share the same frequency of occurrence. In rare cases the occlusal surfaces of impacted molars are united by the same follicular space and the roots pointing in opposite direction; these are called kissing molars. In some cases, a supernumerary fourth molar can be seen as unerupted and, in this case, such a supernumerary, deeply impacted fourth molar is seen neighboring kissing molars. The extraction of deeply impacted wisdom molars from the mandible may necessitate excessive bone removal and it causes complications such as damage to the inferior alveolar nerve and iatrogenic fractures of the mandible. This case report describes the use of the sagittal split osteotomy technique to avoid extensive bone removal and protect the inferior alveolar nerve during surgical extruction of multiple impacted teeth. PMID:27429810

  7. Solvation of a probe molecule by fluid supercooled water in a hydrogel at 200 K.

    PubMed

    Santangelo, Maria Grazia; Levantino, Matteo; Cupane, Antonio; Jeschke, Gunnar

    2008-12-11

    By combining electron paramagnetic resonance (EPR) measurements on a nitroxide probe and differential scanning calorimetry (DSC), we demonstrate existence of liquid supercooled water in a silica hydrogel with high hydration level down to temperatures of at least 198 K. Besides the major fraction of liquid supercooled water, a minor fraction crystallizes at about 236 K during cooling and melts at 246 K during heating. The liquid domains are of sufficient size to solvate the nearly spherical paramagnetic probe molecule TEMPO with a diameter of about 6 A. Analysis of EPR spectra provides the rotational correlation time of the probe that is further used to compare the viscosity of the supercooled water with the one of bulk water. In the temperature interval investigated, the supercooled water behaves as a fragile liquid and eventually solidifies at 120 K to a glass that incorporates the probe molecules. PMID:19053683

  8. Freezing Behavior of a Supercooled Water Droplet Impacting on Surface Using Dual-Luminescent Imaging Technique

    NASA Astrophysics Data System (ADS)

    Tanaka, Mio; Morita, Katsuaki; Yamamoto, Makoto; Sakaue, Hirotaka

    2015-11-01

    A collision of a supercooled-water droplet on an object creates ice accretion on its surface. These icing problems can be seen in any cold environments and may lead to severe damages on aircrafts, ships, power cables, trees, road signs, and architectures. To solve these problems, various studies on ice-prevention and ice-prediction techniques have been conducted. It is very important to know the detail freezing mechanism of supercooled water droplets to propose or improve those techniques. The icing mechanism of a single supercooled-water droplet impacting on object surface would give us great insights for constructing those techniques. In the present study, we use a dual-luminescent imaging technique to measure the time-resolved temperatures of a supercooled water droplet impacting with different speed. The technique we applied consists of high-speed color camera and two luminescent probes. We will report the current status of this experiment in the presentation.

  9. Supercooling and the Mpemba effect: When hot water freezes quicker than cold

    NASA Astrophysics Data System (ADS)

    Auerbach, David

    1995-10-01

    Temperature measurements taken near vessel walls show that initially hot water may well begin to freeze quicker than cold. This is not, as previously surmised, due to the cooling history of the water (e.g., air expulsion during heating). Rather, supercooling virtually always takes place. On those occasions where the cold water supercools sufficiently more than the hot the Mpemba scenario is the following: The hot water supercools, but only slightly, before spontaneously freezing. Superficially it looks completely frozen. The cold water (in larger volume than that of the hot sample) supercools to a lower local temperature than the hot before it spontaneously freezes. This scenario can occur more often for ambient cooling temperatures between -6 °C and -12 °C.

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

    PubMed Central

    Ishikawa, Masaya; Oda, Asuka; Fukami, Reiko; Kuriyama, Akira

    2015-01-01

    Wintering Sasa senanensis, dwarf bamboo, is known to employ deep supercooling as the mechanism of cold hardiness in most of its tissues from leaves to rhizomes. The breakdown of supercooling in leaf blades has been shown to proceed in a random and scattered manner with a small piece of tissue surrounded by longitudinal and transverse veins serving as the unit of freezing. The unique cold hardiness mechanism of this plant was further characterized using current year leaf blades. Cold hardiness levels (LT20: the lethal temperature at which 20% of the leaf blades are injured) seasonally increased from August (−11°C) to December (−20°C). This coincided with the increases in supercooling capability of the leaf blades as expressed by the initiation temperature of low temperature exotherms (LTE) detected in differential thermal analyses (DTA). When leaf blades were stored at −5°C for 1–14 days, there was no nucleation of the supercooled tissue units either in summer or winter. However, only summer leaf blades 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. 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

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

    PubMed

    Ishikawa, Masaya; Oda, Asuka; Fukami, Reiko; Kuriyama, Akira

    2014-01-01

    Wintering Sasa senanensis, dwarf bamboo, is known to employ deep supercooling as the mechanism of cold hardiness in most of its tissues from leaves to rhizomes. The breakdown of supercooling in leaf blades has been shown to proceed in a random and scattered manner with a small piece of tissue surrounded by longitudinal and transverse veins serving as the unit of freezing. The unique cold hardiness mechanism of this plant was further characterized using current year leaf blades. Cold hardiness levels (LT20: the lethal temperature at which 20% of the leaf blades are injured) seasonally increased from August (-11°C) to December (-20°C). This coincided with the increases in supercooling capability of the leaf blades as expressed by the initiation temperature of low temperature exotherms (LTE) detected in differential thermal analyses (DTA). When leaf blades were stored at -5°C for 1-14 days, there was no nucleation of the supercooled tissue units either in summer or winter. However, only summer leaf blades 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. 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

  12. Deeply Virtual Exclusive Processes and Generalized Parton Distributions

    SciTech Connect

    ,

    2011-06-01

    The goal of the comprehensive program in Deeply Virtual Exclusive Scattering at Jefferson Laboratory is to create transverse spatial images of quarks and gluons as a function of their longitudinal momentum fraction in the proton, the neutron, and in nuclei. These functions are the Generalized Parton Distributions (GPDs) of the target nucleus. Cross section measurements of the Deeply Virtual Compton Scattering (DVCS) reaction ep {yields} ep{gamma} in Hall A support the QCD factorization of the scattering amplitude for Q^2 {>=} 2 GeV^2. Quasi-free neutron-DVCS measurements on the Deuteron indicate sensitivity to the quark angular momentum sum rule. Fully exclusive H(e, e'p{gamma} ) measurements have been made in a wide kinematic range in CLAS with polarized beam, and with both unpolarized and longitudinally polarized targets. Existing models are qualitatively consistent with the JLab data, but there is a clear need for less constrained models. Deeply virtual vector meson production is studied in CLAS. The 12 GeV upgrade will be essential for for these channels. The {rho} and {omega} channels reactions offer the prospect of flavor sensitivity to the quark GPDs, while the {phi}-production channel is dominated by the gluon distribution.

  13. Persistence of deeply sourced iron in the Pacific Ocean.

    PubMed

    Horner, Tristan J; Williams, Helen M; Hein, James R; Saito, Mak A; Burton, Kevin W; Halliday, Alex N; Nielsen, Sune G

    2015-02-01

    Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe-Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface. PMID:25605900

  14. Persistence of deeply sourced iron in the Pacific Ocean

    PubMed Central

    Horner, Tristan J.; Williams, Helen M.; Hein, James R.; Saito, Mak A.; Burton, Kevin W.; Halliday, Alex N.; Nielsen, Sune G.

    2015-01-01

    Biological carbon fixation is limited by the supply of Fe in vast regions of the global ocean. Dissolved Fe in seawater is primarily sourced from continental mineral dust, submarine hydrothermalism, and sediment dissolution along continental margins. However, the relative contributions of these three sources to the Fe budget of the open ocean remains contentious. By exploiting the Fe stable isotopic fingerprints of these sources, it is possible to trace distinct Fe pools through marine environments, and through time using sedimentary records. We present a reconstruction of deep-sea Fe isotopic compositions from a Pacific Fe−Mn crust spanning the past 76 My. We find that there have been large and systematic changes in the Fe isotopic composition of seawater over the Cenozoic that reflect the influence of several, distinct Fe sources to the central Pacific Ocean. Given that deeply sourced Fe from hydrothermalism and marginal sediment dissolution exhibit the largest Fe isotopic variations in modern oceanic settings, the record requires that these deep Fe sources have exerted a major control over the Fe inventory of the Pacific for the past 76 My. The persistence of deeply sourced Fe in the Pacific Ocean illustrates that multiple sources contribute to the total Fe budget of the ocean and highlights the importance of oceanic circulation in determining if deeply sourced Fe is ever ventilated at the surface. PMID:25605900

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

    SciTech Connect

    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.

  16. Supercooled large drop detection with NASA's Icing Remote Sensing System

    NASA Astrophysics Data System (ADS)

    Serke, David J.; Reehorst, Andrew L.; Politovich, Marcia K.

    2010-10-01

    In-flight icing occurs when aircraft impact supercooled liquid drops. The supercooled liquid freezes on contact and the accreted ice changes a plane's aerodynamic characteristics, which can lead to dangerous loss of control. NASA's Icing Remote Sensing System consists of a multi-channel radiometer, a laser ceilometer and a vertically-pointing Kaband radar, whos fields are merged with internal software logic to arrive at a hazard classification for in-flight icing. The radiometer is used to derive atmospheric temperature soundings and integrated liquid water and the ceilometer and radar are used to define cloud boundaries. The integrated liquid is then distributed within the determined cloud boundaries and layers to arrive at liquid water content profiles, which if present below freezing are categorized as icing hazards. This work outlines how the derived liquid water content and measured Ka-band reflectivity factor profiles can be used to derive a vertical profile of radar-estimated particle size. This is only possible because NASA's system arrives at independent and non-correlated measures of liquid water and reflectivity factor for a given range volume. The size of the drops significantly effect the drop collection efficiency and the location that icing accretion occurs on the craft's superstructure and thus how a vehicle's performance is altered. Large drops, generally defined as over 50 μm in diameter, tend to accrete behind the normal ice protected areas of the leading edge of the wing and other control surfaces. The NASA Icing Remote Sensing System was operated near Montreal, Canada for the Alliance Icing Research Study II in 2003 and near Cleveland, Ohio from 2006 onward. In this study, we present case studies to show how NASA's Icing Remote Sensing System can detect and differentiate between no icing, small drop and large drop in-flight icing hazards to aircraft. This new product provides crucial realtime hazard detection capabilities which improve

  17. Mechanical annealing in the flow of supercooled metallic liquid

    SciTech Connect

    Zhang, Meng; Dai, Lan Hong; Liu, Lin

    2014-08-07

    Flow induced structural evolution in a supercooled metallic liquid Vit106a (Zr{sub 58.5}Cu{sub 15.6}Al{sub 10.3}Ni{sub 12.8}Nb{sub 2.8}, at. %) was investigated via uni-axial compression combined with differential scanning calorimeter (DSC). Compression tests at strain rates covering the transition from Newtonian flow to non-Newtonian flow and at the same strain rate 2 × 10{sup −1} s{sup −1} to different strains were performed at the end of glass transition (T{sub g-end} = 703 K). The relaxation enthalpies measured by DSC indicate that the samples underwent non-Newtonian flow contain more free volume than the thermally annealed sample (703 K, 4 min), while the samples underwent Newtonian flow contain less, namely, the free volume of supercooled metallic liquids increases in non-Newtonian flow, while decreases in Newtonian flow. The oscillated variation of the relaxation enthalpies of the samples deformed at the same strain rate 2 × 10{sup −1} s{sup −1} to different strains confirms that the decrease of free volume was caused by flow stress, i.e., “mechanical annealing.” Micro-hardness tests were also performed to show a similar structural evolution tendency. Based on the obtained results, the stress-temperature scaling in the glass transition of metallic glasses are supported experimentally, as stress plays a role similar to temperature in the creation and annihilation of free volume. In addition, a widening perspective angle on the glass transition of metallic glasses by exploring the 3-dimensional stress-temperature-enthalpy phase diagram is presented. The implications of the observed mechanical annealing effect on the amorphous structure and the work-hardening mechanism of metallic glasses are elucidated based on atomic level stress model.

  18. Slowing dynamics in supercooled liquids and other soft materials

    NASA Astrophysics Data System (ADS)

    Yardimci, Hasan

    The slow structural dynamics displayed by supercooled liquids and the transition to an out-of-equilibrium glass state that they engender are among the most challenging issues in condensed matter physics. This thesis reports experimental studies designed to elucidate central aspects of these slow dynamics and the nature of the glass state. The subjects of these studies include glass forming molecular liquids and other soft materials that have been advanced as model glassy systems such as clay suspensions and block copolymer micelle solutions. The main experimental techniques employed in these investigations have been dielectric susceptibility and neutron scattering. In the first half of this thesis, we report frequency-dependent dielectric susceptibility measurements characterizing the evolution in the dynamical properties, or aging, of two supercooled liquids, sorbitol and xylitol, quenched below their calorimetric glass transition temperatures, Tg. In addition to the alpha relaxation that tracks the structural dynamics, the susceptibilities of both liquids possess a secondary Johari-Goldstein relaxation at higher frequencies. Following a quench below Tg, the susceptibility slowly approaches equilibrium behavior. For both liquids features of the Johari-Goldstein relaxation display a dependence on the time since the quench, or aging time, that is very similar to the age dependence of the alpha peak. Implications of these findings for aging in glasses and the nature of Johari-Goldstein relaxation are discussed. Further investigation of the aging in sorbitol reveals that it displays memory strikingly similar to that of a variety of glassy materials, particularly spin glasses. During a temporary stop in cooling, the susceptibility changes with time due to aging. The memory is revealed upon reheating as the susceptibility retraces these changes. To investigate the out-of-equilibrium state of the liquid as it displays this memory, we have employed a set of intricate

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

    NASA Astrophysics Data System (ADS)

    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

  20. Phonon interpretation of the 'boson peak' in supercooled liquids.

    PubMed

    Grigera, T S; Martín-Mayor, V; Parisi, G; Verrocchio, P

    2003-03-20

    Glasses are amorphous solids, in the sense that they display elastic behaviour. In crystalline solids, elasticity is associated with phonons, which are quantized vibrational excitations. Phonon-like excitations also exist in glasses at very high (terahertz; 10(12) Hz) frequencies; surprisingly, these persist in the supercooled liquids. A universal feature of such amorphous systems is the boson peak: the vibrational density of states has an excess compared to the Debye squared-frequency law. Here we investigate the origin of this feature by studying the spectra of inherent structures (local minima of the potential energy) in a realistic glass model. We claim that the peak is the signature of a phase transition in the space of the stationary points of the energy, from a minima-dominated phase (with phonons) at low energy to a saddle-point-dominated phase (without phonons). The boson peak moves to lower frequencies on approaching the phonon-saddle transition, and its height diverges at the critical point. Our numerical results agree with the predictions of euclidean random matrix theory on the existence of a sharp phase transition between an amorphous elastic phase and a phonon-free one. PMID:12646916

  1. Homogeneous Nucleation Rate for Highly Supercooled Cirrus Cloud Droplets.

    NASA Astrophysics Data System (ADS)

    Sassen, Kenneth; Dodd, Gregory C.

    1988-04-01

    A mixed-phase hydrometer growth model has been applied to determining the nucleation mode and rate responsible for the glaciation of a highly supercooled liquid cloud studied jointly by ground-based polarization lidar and aircraft in situ probes. The cloud droplets were detected at the base of an orographically induced cirrus cloud at temperatures between 34.3° and 37.3°C. The vertical distribution above cloud base of two independent data quantities, the aircraft-measured water and ice particle concentrations and the lidar linear depolarization ratio, have been compared to model predictions for both the homogeneous and heterogeneous drop-freezing. modes. It is concluded that, although activated ice nuclei may have contributed to the glaciation of the cloud, homogeneous nucleation was the dominant mode. Accordingly, a homogeneous nucleation rate 106 times greater than that predicted by classical theory, but 103 times less than laboratory measurements would suggest is found to be appropriate at the measured cloud temperatures.

  2. Plasticity in the Supercooled Liquid Region of Bulk Metallic Glasses

    SciTech Connect

    Nieh, T G; Wadsworth, J; Liu, C T; Ice, G E

    2000-10-30

    Intensive efforts have been carried out over the past decade to develop means to slow down the phase transformation kinetics during the forming of metallic glasses. As a result of these efforts, some metallic glasses can now be fabricated in bulk forms (BMG) from the liquid state at cooling rates on the order of 1-10 K/s, which is close to that of conventional casting. This enables the production of bulk amorphous alloys with a thickness of {approx}10 mm. While advances in amorphous metallic alloy development have been impressive, they have been made largely through experience [1]. Three main conclusions drawn from this study are: (1) Bulk metallic glasses generally have excellent mechanical formability in the supercooled liquid region. (2) Bulk metallic glasses may not be necessarily behave like a Newtonian fluid (i.e. m=1). The non-Newtonian behavior is associated with glass instability during deformation. (3) Multi-component Bulk metallic glasses can be used as the precursor of a nanocrystalline solid. However, the nanocrystalline solid is not necessarily superplastic. The non-superplastic behavior is caused by the difficult strain accommodation at grain triple junctions.

  3. Collective effects on activated segmental relaxation in supercooled polymer melts

    NASA Astrophysics Data System (ADS)

    Mirigian, Stephen; Schweizer, Kenneth

    2013-03-01

    We extend the polymer nonlinear Langevin equation (NLE) theory of activated segmental dynamics in supercooled polymer melts in two new directions. First, a well-defined mapping from real monomers to a freely-jointed chain is formulated that retains information about chain stiffness, monomer volume, and the amplitude of thermal density fluctuations. Second, collective effects beyond the local cage scale are included based on an elastic solid-state perspective in the ``shoving model'' spirit which accounts for longer range contributions to the activation barrier. In contrast to previous phenomenological treatments of this model, we formulate an explicit microscopic picture of the hopping event, and derive, not assume, that the collective barrier is directly related to the elastic shear modulus. Local hopping is thus renormalized by collective motions of the surroundings that are required to physically accommodate it. Using the PRISM theory of structure, and known compressibility and chain statistics information, quantitative applications of the new theory to predict the temperature and chain length dependence of the alpha time, shear modulus, and fragility are carried out for a range of real polymer liquids and compared to experiment.

  4. Deeply virtual Compton scattering via color dipoles: Nonperturbative effects

    SciTech Connect

    Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M.

    2009-02-01

    We study the deeply virtual Compton scattering amplitude within the color dipole approach. The light-cone wave function of a real photon is evaluated in the instanton vacuum model. Our parameter-free calculations are able to describe H1 data, both the absolute values and the t dependences, at medium-high values of Q{sup 2}. The Q{sup 2} dependence is found to be sensitive to the choice of the phenomenological cross section fitted to deep-inelastic scattering data.

  5. Explosive fluid transmitted shock method for mining deeply buried coal

    DOEpatents

    Archibald, Paul B.

    1976-06-22

    A method for recovering coal from deeply buried deposits comprising drilling a hole down into a coal seam, filling the hole with water, and periodically detonating an explosive charge at the bottom of the water-filled hole. The water transmits the explosive shock wave to the face of the coal seam, thereby fracturing and dislodging the coal. The resulting suspension of loose coal in water is then pumped to the surface where the coal is recovered and the water is recycled to the mining operation.

  6. Exchange of deeply trapped and interstitial hydrogen in silicon

    SciTech Connect

    Tuttle, B.; Van de Walle, C.G.; Adams, J.B.

    1999-02-01

    Using {ital ab initio} density-functional calculations, we examine possible exchange mechanisms between an interstitial hydrogen atom and a deeply bound H at a silicon-hydrogen bond. We determine a low-energy pathway for exchange, which involves an intermediate, metastable {equivalent_to}SiH{sub 2} complex with both hydrogen atoms strongly bound to the silicon atom. The energy barrier for the exchange process is E{sub ex}{lt}0.2 eV, consistent with observations of hydrogen-deuterium exchange in a-Si:H(D) films. {copyright} {ital 1999} {ital The American Physical Society}

  7. Locally Controlled Deeply Saturated Fiber Optic Parametric Amplifiers

    NASA Astrophysics Data System (ADS)

    Nissim, Ron Reuven

    A new class of highly efficient Optical Parametric Amplifiers (OPA) is explored in this dissertation, which have the potential to reduce the power requirement on the pump and enable new functionalities. This originates from the simple notion that figure of merit (FoM) of an OPA is proportional to the product of the pump power and amplifier's length and nonlinearity. Silica fibers have been developed for over five decades and offer unparalleled transparency. By merely extending the fiber, i.e. the amplifier's length, a high FoM amplifier can be formed while keeping the pump at a moderate, sub-Watt power level. Unfortunately, optical fibers are inherently non-uniform. Their core size fluctuates along the fiber on a nanometer scale which is on the order of the fiber's molecular constituents. It is currently established that the performance of a fiber-based OPA (FOPA) is dictated by its stochastic nature. In fact, given a moderate pump power level, the highly efficient OPA will be required to maintain a strict phase matching condition across hundreds of meters. Facing this challenge, this dissertation focuses on a locally-controlled, high FoM FOPA. A high FoM FOPA operates in the deeply saturated regime in which a weak signal saturates the amplifier and depletes the pump power, effectively generating an inverse response of the pump output power to the signal input power. Given FOPAs' inhomogeneous nature, the performance limit of deeply saturated FOPAs is studied. So far, FOPAs have been commonly treated as a uniform entity; however, this study discovers unique features of the system which originate from and are strongly influenced by the fiber's inhomogeneous nature. One major example is the non-reciprocal response of deeply saturated FOPAs. It was found that deeply saturated FOPAs perform very highly, as the pump can respond to a rapidly varying (sub-THz) weak (sub-muW) signal. This is a novel method which obtained orders of magnitude improvement over current

  8. Beam-charge azimuthal asymmetry and deeply virtual Compton scattering

    NASA Astrophysics Data System (ADS)

    Airapetian, A.; Akopov, N.; Akopov, Z.; Amarian, M.; Andrus, A.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetissian, E.; Bailey, P.; Balin, D.; Beckmann, M.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Böttcher, H.; Borissov, A.; Borysenko, A.; Bouwhuis, M.; Brüll, A.; Bryzgalov, V.; Capiluppi, M.; Capitani, G. P.; Chen, T.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; de Leo, R.; Demey, M.; de Nardo, L.; de Sanctis, E.; Devitsin, E.; di Nezza, P.; Dreschler, J.; Düren, M.; Ehrenfried, M.; Elalaoui-Moulay, A.; Elbakian, G.; Ellinghaus, F.; Elschenbroich, U.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Funel, A.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Garrow, K.; Gaskell, D.; Gavrilov, G.; Gharibyan, V.; Grebeniouk, O.; Gregor, I. M.; Hadjidakis, C.; Hafidi, K.; Hartig, M.; Hasch, D.; Hesselink, W. H. A.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hommez, B.; Hristova, I.; Iarygin, G.; Ivanilov, A.; Izotov, A.; Jackson, H. E.; Jgoun, A.; Kaiser, R.; Kinney, E.; Kisselev, A.; Kobayashi, T.; Kopytin, M.; Korotkov, V.; Kozlov, V.; Krauss, B.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Laziev, A.; Lenisa, P.; Liebing, P.; Linden-Levy, L. A.; Lorenzon, W.; Lu, H.; Lu, J.; Lu, S.; Ma, B.-Q.; Maiheu, B.; Makins, N. C. R.; Mao, Y.; Marianski, B.; Marukyan, H.; Masoli, F.; Mexner, V.; Meyners, N.; Michler, T.; Mikloukho, O.; Miller, C. A.; Miyachi, Y.; Muccifora, V.; Murray, M.; Nagaitsev, A.; Nappi, E.; Naryshkin, Y.; Negodaev, M.; Nowak, W.-D.; Oganessyan, K.; Ohsuga, H.; Osborne, A.; Pickert, N.; Potterveld, D. H.; Raithel, M.; Reggiani, D.; Reimer, P. E.; Reischl, A.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubacek, L.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Sanjiev, I.; Savin, I.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seele, J.; Seidl, R.; Seitz, B.; Shanidze, R.; Shearer, C.; Shibata, T.-A.; Shutov, V.; Sinram, K.; Sommer, W.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Stenzel, H.; Stewart, J.; Stinzing, F.; Tait, P.; Tanaka, H.; Taroian, S.; Tchuiko, B.; Terkulov, A.; Trzcinski, A.; Tytgat, M.; Vandenbroucke, A.; van der Nat, P. B.; van der Steenhoven, G.; van Haarlem, Y.; Vikhrov, V.; Vincter, M. G.; Vogel, C.; Volmer, J.; Wang, S.; Wendland, J.; Ye, Y.; Ye, Z.; Yen, S.; Zihlmann, B.; Zupranski, P.

    2007-01-01

    The first observation of an azimuthal cross section asymmetry with respect to the charge of the incoming lepton beam is reported from a study of hard exclusive electroproduction of real photons. The data have been accumulated by the HERMES experiment at DESY, in which the HERA 27.6 GeV electron or positron beam scattered off an unpolarized hydrogen gas target. The observed asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply virtual Compton scattering (DVCS) process. The interference term is sensitive to DVCS amplitudes, which provide the most direct access to generalized parton distributions.

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

    NASA Astrophysics Data System (ADS)

    Qunzhi, Zhao; Xuelai, Zhang; Xiaoyang, Liang; Tiantian, Liu; Xiaoxue, Luo

    2015-04-01

    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.

  10. PREFACE: Fourh Workshop on Non-Equilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials

    NASA Astrophysics Data System (ADS)

    Andreozzi, Laura; Giordano, Marco; Leporini, Dino; Tosi, Mario

    2007-04-01

    This special issue of Journal of Physics: Condensed Matter presents the Proceedings of the Fourh Workshop on Non-Equilibrium Phenomena in Supercooled Fluids, Glasses and Amorphous Materials, held in Pisa from 17-22 September 2006. This was the fourth of a series of workshops on this theme started in 1995 as a joint initiative of the Università di Pisa and the Scuola Normale Superiore. The 2006 edition was attended by about 200 participants from Europe, Asia and the Americas. As for the earlier workshops, the main objective was to bring together scientists from different areas of science, technology and engineering, to comparatively discuss experimental facts and theoretical predictions on the dynamical processes that occur in supercooled fluids and other disordered materials in non-equilibrium states. The underlying conceptual unity of the field provides a common background for the scientific community working in its various areas. In this edition the number of sessions was increased to cover a wider range of topics of general and current interest, in a larger number of stimulating lectures. The core of the workshop was a set of general lectures followed by more specific presentations on current issues in the main areas of the field. The sessions were in sequence devoted to: non-equilibrium dynamics, aging and secondary relaxations, biomaterials, polyamorphism and water, polymer dynamics I, complex systems, pressure-temperature scaling, thin films, nanometre length-scale studies, folded states of proteins and polymer crystals, theoretical aspects and energy landscape approaches, relaxation and heterogeneous dynamics, rheology in fluids and entangled polymers, biopolymers, and polymer dynamics II. We thank the session chairmen and all speakers for the high quality of their contributions. The structure of this issue of the proceedings follows the sequence of the oral presentations in the workshop, complemented by some papers selected from the poster sessions. Two

  11. Dosimeter for measuring skin dose and more deeply penetrating radiation

    DOEpatents

    Jones, Donald E.; Parker, DeRay; Boren, Paul R.

    1981-01-01

    A personnel dosimeter includes a plurality of compartments containing thermoluminescent dosimeter phosphors for registering radiation dose absorbed in the wearer's sensitive skin layer and for registering more deeply penetrating radiation. Two of the phosphor compartments communicate with thin windows of different thicknesses to obtain a ratio of shallowly penetrating radiation, e.g. beta. A third phosphor is disposed within a compartment communicating with a window of substantially greater thickness than the windows of the first two compartments for estimating the more deeply penetrating radiation dose. By selecting certain phosphors that are insensitive to neutrons and by loading the holder material with netruon-absorbing elements, energetic neutron dose can be estimated separately from other radiation dose. This invention also involves a method of injection molding of dosimeter holders with thin windows of consistent thickness at the corresponding compartments of different holders. This is achieved through use of a die insert having the thin window of precision thickness in place prior to the injection molding step.

  12. ASSESSMENT OF SEISMIC ANALYSIS METHODOLOGIES FOR DEEPLY EMBEDDED NPP STRUCTURES.

    SciTech Connect

    XU, J.; MILLER, C.; COSTANTINO, C.; HOFMAYER, C.; GRAVES, H. .

    2005-07-01

    Several of the new generation nuclear power plant designs have structural configurations which are proposed to be deeply embedded. Since current seismic analysis methodologies have been applied to shallow embedded structures (e.g., ASCE 4 suggest that simple formulations may be used to model embedment effect when the depth of embedment is less than 30% of its foundation radius), the US Nuclear Regulatory Commission is sponsoring a program at the Brookhaven National Laboratory with the objective of investigating the extent to which procedures acceptable for shallow embedment depths are adequate for larger embedment depths. This paper presents the results of a study comparing the response spectra obtained from two of the more popular analysis methods for structural configurations varying from shallow embedment to complete embedment. A typical safety related structure embedded in a soil profile representative of a typical nuclear power plant site was utilized in the study and the depths of burial (DOB) considered range from 25-100% the height of the structure. Included in the paper are: (1) the description of a simplified analysis and a detailed approach for the SSI analyses of a structure with various DOB, (2) the comparison of the analysis results for the different DOBs between the two methods, and (3) the performance assessment of the analysis methodologies for SSI analyses of deeply embedded structures. The resulting assessment from this study has indicated that simplified methods may be capable of capturing the seismic response for much deeper embedded structures than would be normally allowed by the standard practice.

  13. Liquid structure and temperature invariance of sound velocity in supercooled Bi melt

    SciTech Connect

    Emuna, M.; Mayo, M.; Makov, G.; Greenberg, Y.; Caspi, E. N.; Yahel, E.; Beuneu, B.

    2014-03-07

    Structural rearrangement of liquid Bi in the vicinity of the melting point has been proposed due to the unique temperature invariant sound velocity observed above the melting temperature, the low symmetry of Bi in the solid phase and the necessity of overheating to achieve supercooling. The existence of this structural rearrangement is examined by measurements on supercooled Bi. The sound velocity of liquid Bi was measured into the supercooled region to high accuracy and it was found to be invariant over a temperature range of ∼60°, from 35° above the melting point to ∼25° into the supercooled region. The structural origin of this phenomenon was explored by neutron diffraction structural measurements in the supercooled temperature range. These measurements indicate a continuous modification of the short range order in the melt. The structure of the liquid is analyzed within a quasi-crystalline model and is found to evolve continuously, similar to other known liquid pnictide systems. The results are discussed in the context of two competing hypotheses proposed to explain properties of liquid Bi near the melting: (i) liquid bismuth undergoes a structural rearrangement slightly above melting and (ii) liquid Bi exhibits a broad maximum in the sound velocity located incidentally at the melting temperature.

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

    NASA Astrophysics Data System (ADS)

    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. Experimental Study on the Effect of the Ultrasonic Wave on the Freezing of the Supercooled Water

    NASA Astrophysics Data System (ADS)

    Hozumi, Tsutomu; Saito, Akio; Okawa, Seiji; Matsui, Tatsuyuki

    In order to confirm the effect of ultrasonic wave on the freezing of supercooled water, various level of ultrasonic waves were applied to the supercooled water. The frequencies of the waves applied were 28kHz, 40kHz, 45kHz, 50kHz, and 1MHz. In order to clarify the mechanism of the effect of the ultrasonic wave, several factors were examined changing the experimental conditions and the results were compared each other; the factors were the existence of a free surface or oil -water interface, the volume of water, the purity of water and the existence of metal bar inserted. Each test section was cooled at a constant cooling rate and the ultrasonic waves were applied to each test section continuously, varying the frequency and the intensity. The experiments were carried out until the water in the test section solidified. The degree of supercooling at the freezing is determined by measuring the temperature just before a rapid increment of temperature due to freezing. It was found that the existence of a free surface and insertion of a metal bar with an addition to the ultrasonic wave have effects on the freezing of supercooled water. On the other hand, if oil-water interface or no metal bar insertion was selected as the experimental condition, there was no influence of the ultrasonic wave on the freezing of the supercooled water even the frequency and the intensity were varied.

  16. Fishbone Mode Excited by Deeply Trapped Energetic Beam Ions in EAST

    NASA Astrophysics Data System (ADS)

    Zheng, Ting; Wu, Bin; Xu, Liqing; Hu, Chundong; Zang, Qing; Ding, Siye; Li, Yingying; Wu, Xingquan; Wang, Jinfang; Shen, Biao; Zhong, Guoqiang; Li, Hao; Shi, Tonghui; EAST Team

    2016-06-01

    This paper describes the fishbone mode phenomena during the injection of high-power neutral beams in EAST (Experimental Advanced Superconducting Tokamak). The features of the fishbone mode are presented. The change in frequency of the mode during a fishbone burst is from 1 kHz to 6 kHz. The nonlinear behavior of the fishbone mode is analyzed by using a prey-predator model, which is consistent with the experimental results. This model indicates that the periodic oscillations of the fishbone mode always occur near the critical value of fast ion beta. Furthermore, the neutral beam analysis for the discharge is done by using the NUBEAM module of the TRANSP code. According to the numerical simulation results and theoretical calculation, it can be concluded that the fishbone mode is driven by the deeply trapped energetic beam ions in EAST. supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB101001, 2014DFG61950 and 2013GB112003) and National Natural Science Foundation of China (Nos. 11175211 and 11275233)

  17. An experimental study of freezing of supercooled water droplet on solid surface

    NASA Astrophysics Data System (ADS)

    Alekseenko, S. V.; Mendig, C.; Schulz, M.; Sinapius, M.; Prykhodko, O. A.

    2016-05-01

    Results of experimental investigations of the freezing of immobile water droplet on an aluminum plate are presented. The process was studied with the aid of a high-speed photo camera. The freezing of supercooled water contained in the surface droplet proceeds in a few stages: (i) preliminary heating of water and nucleation of ice microcrystals, (ii) relatively fast formation of the ice-liquid system with a transition to the state of thermodynamic equilibrium near the freezing temperature, and (iii) slow process of complete freezing. The rate and duration of each stage and the time of delay between the moment of action upon the supercooled droplet and the onset of freezing are estimated. Processes of supercooled and nonsupercooled water solidification are compared.

  18. Nature of the first-order liquid-liquid phase transition in supercooled silicon

    NASA Astrophysics Data System (ADS)

    Zhao, G.; Yu, Y. J.; Tan, X. M.

    2015-08-01

    The first-order liquid-liquid phase transition in supercooled Si is revisited by long-time first-principle molecular dynamics simulations. As the focus of the present paper, its nature is revealed by analyzing the inherent structures of low-density liquid (LDL) and high-density liquid (HDL). Our results show that it is a transition between a sp3-hybridization LDL and a white-tin-like HDL. This uncovers the origin of the semimetal-metal transition accompanying it and also proves that HDL is the metastable extension of high temperature equilibrium liquid into the supercooled regime. The pressure-temperature diagram of supercooled Si thus can be regarded in some respects as shifted reflection of its crystalline phase diagram.

  19. Liquid-to-crystal nucleation: Automated lag-time apparatus to study supercooled liquids

    NASA Astrophysics Data System (ADS)

    Heneghan, A. F.; Wilson, P. W.; Wang, Genmiao; Haymet, A. D. J.

    2001-10-01

    The statistics of liquid-to-crystal nucleation are studied using an automated lag-time apparatus. A single 500 μL sample of distilled water is repeatedly supercooled to a fixed temperature below its equilibrium freezing temperature, held until freezing occurred, and then thawed. Our raw data is then a set of approximately 300 lag-times for each of three set supercooling temperatures. In each case, a small insoluble AgI crystal was added to ensure heterogeneous nucleation and average nucleation temperatures around ΔT=8 K. The distribution of lag-times is analyzed, and shown to be well approximated by a single exponential decay, with average lag-times in the range of 1000-3000 seconds. This average lag-time decreases markedly at deeper levels of supercooling, and for the present data, this decrease is fit equally well by exponential, power law decay, and classical nucleation functional forms.

  20. COMMENT: Comment on `Structure of supercooled liquid silicon' by Ansell et al

    NASA Astrophysics Data System (ADS)

    Angell, C. A.; Borick, S. S.

    1999-10-01

    We correct a statement made in a recent paper (Angell S et al 1998 J. Phys.: Condens. Matter 10 L73-8) that computer simulations on supercooled liquid silicon were not available. We further point out that the simulations that have been made provide an important confirmation of the findings of Angell et al, from the x-ray diffraction studies, that the Si coordination number rapidly decreases in the supercooling range. Of particular interest is the observation that, at the limit of the 340 K supercooling reported in Angell et al, the laboratory liquid has the same coordination number that the simulated system reaches at the temperature of its first order liquid-liquid transition. This implies that the crystallization is promoted by the liquid-liquid transition, as is also seen in the simulation. We point out other systems in which such provocative behaviour should be found.

  1. Communication: Minimum in the thermal conductivity of supercooled water: A computer simulation study

    SciTech Connect

    Bresme, F.; Biddle, J. W.; Sengers, J. V.; Anisimov, M. A.

    2014-04-28

    We report the results of a computer simulation study of the thermodynamic properties and the thermal conductivity of supercooled water as a function of pressure and temperature using the TIP4P-2005 water model. The thermodynamic properties can be represented by a two-structure equation of state consistent with the presence of a liquid-liquid critical point in the supercooled region. Our simulations confirm the presence of a minimum in the thermal conductivity, not only at atmospheric pressure, as previously found for the TIP5P water model, but also at elevated pressures. This anomalous behavior of the thermal conductivity of supercooled water appears to be related to the maximum of the isothermal compressibility or the minimum of the speed of sound. However, the magnitudes of the simulated thermal conductivities are sensitive to the water model adopted and appear to be significantly larger than the experimental thermal conductivities of real water at low temperatures.

  2. Bulk glassy Cu-based alloys with a large supercooled liquid region of 110 K

    NASA Astrophysics Data System (ADS)

    Inoue, Akihisa; Zhang, Wei

    2003-09-01

    The replacement of Cu by 5%Ag for Cu50Hf45Al5 glassy alloy was found to increase significantly the stability of supercooled liquid against crystallization. The supercooled liquid region reached as large as 110 K for Cu45Hf45Al5Ag5. The extension of the supercooled liquid region is due to an increase in the crystallization temperature, accompanying the change in the primary crystalline phases. The effectiveness of Ag addition was interpreted to result from the retardation of long-range atomic rearrangements for the progress of crystallization reaction. The selection of the quaternary composition enabled us to form bulk glassy alloys with diameters up to 3 mm. The Young's modulus and compressive fracture strength of the 5%Ag-containing alloy are 119 GPa and 2220 MPa, respectively.

  3. Measurement of deeply virtual compton scattering beam-spin asymmetries.

    PubMed

    Girod, F X; Niyazov, R A; Avakian, H; Ball, J; Bedlinskiy, I; Burkert, V D; De Masi, R; Elouadrhiri, L; Garçon, M; Guidal, M; Jo, H S; Joo, K; Kubarovsky, V; Kuleshov, S V; MacCormick, M; Niccolai, S; Pogorelko, O; Sabatié, F; Stepanyan, S; Stoler, P; Ungaro, M; Zhao, B; Amaryan, M J; Ambrozewicz, P; Anghinolfi, M; Asryan, G; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Batourine, V; Battaglieri, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Blaszczyk, L; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Casey, L; Chen, S; Cheng, L; Cole, P L; Collins, P; Coltharp, P; Crabb, D; Crede, V; Dashyan, N; De Sanctis, E; De Vita, R; Degtyarenko, P V; Deur, A; Dharmawardane, K V; Dickson, R; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dugger, M; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Eugenio, P; Fedotov, G; Feldman, G; Funsten, H; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Goetz, J T; Gonenc, A; Gothe, R W; Griffioen, K A; Guler, N; Guo, L; Gyurjyan, V; Hafidi, K; Hakobyan, H; Hanretty, C; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Johnstone, J R; Juengst, H G; Kalantarians, N; Kellie, J D; Khandaker, M; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Kossov, M; Krahn, Z; Kramer, L H; Kuhn, J; Kuhn, S E; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Lee, T; Livingston, K; Lu, H Y; Markov, N; Mattione, P; Mazouz, M; McKinnon, B; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Michel, B; Mikhailov, K; Mirazita, M; Miskimen, R; Mokeev, V; Moriya, K; Morrow, S A; Moteabbed, M; Munevar, E; Mutchler, G S; Nadel-Turonski, P; Nasseripour, R; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Nozar, M; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Anefalos Pereira, S; Pierce, J; Pivnyuk, N; Pocanic, D; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Salamanca, J; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabian, Y G; Sharov, D; Shvedunov, N V; Smith, E S; Smith, L C; Sober, D I; Sokhan, D; Stavinsky, A; Stepanyan, S S; Stokes, B E; Strakovsky, I I; Strauch, S; Taiuti, M; Tedeschi, D J; Tkabladze, A; Tkachenko, S; Tur, C; Vineyard, M F; Vlassov, A V; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Zana, L; Zhang, J; Zhao, Z W

    2008-04-25

    The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e p-->epgamma) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x(B) from 0.11 to 0.58, Q2 from 1 to 4.8 GeV2, -t from 0.09 to 1.8 GeV2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A approximately a sinphi/(1+c cosphi). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector. PMID:18518188

  4. Deeply Virtual Compton Scattering Beam-Spin Asymmetries

    SciTech Connect

    F.X. Girod; R.A. Niyazov

    2008-01-24

    The beam spin asymmetries in the hard exclusive electroproduction of photons on the proton (ep -> epg) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x_B from 0.11 to 0.58, Q^2 from 1 to 4.8 GeV^2, -t from 0.09 to 1.8 GeV^2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A = a*sin(phi)/[1+c*cos(phi)]. This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.

  5. Full strength compacts by extrusion of glassy metal powder at the supercooled liquid state

    NASA Astrophysics Data System (ADS)

    Kawamura, Yoshihito; Kato, Hidemi; Inoue, Akihisa; Masumoto, Tsuyoshi

    1995-10-01

    We report the production of full strength compacts of metallic glass by warm extrusion of powders at the supercooled liquid state just above the glass transition temperature. The alloy used was Zr65Al10Ni10Cu15 (at. %) which has the lowest viscosity among Zr-based metallic glasses with large supercooled liquid region. The tensile strength and Young's modulus of the glassy powder compacts were 1520 MPa and 80 GPa, respectively, which are similar to that obtained in the as-cast bulk alloy and melt-spun ribbon. This opens up possibilities of producing high strength amorphous alloys with complex shapes.

  6. Initial stage of nucleation-mediated crystallization of a supercooled melt

    NASA Astrophysics Data System (ADS)

    Chernov, A. A.; Pil'nik, A. A.; Islamov, D. R.

    2016-09-01

    The kinetic model of nucleation-mediated crystallization of a supercooled melt is presented in this work. It correctly takes into account the change in supercooling of the initial phase in the process of formation and evolution of a new phase. The model makes it possible to find the characteristic time of the process, time course of the crystal phase volume, solidified material microstructure. The distinctive feature of the model is the use of the "forbidden" zones in the volume where the formation of new nucleation centers is suppressed.

  7. The vapor pressures of supercooled NHO3/H2O solutions. [in polar stratospheric clouds

    NASA Technical Reports Server (NTRS)

    Hanson, David R.

    1990-01-01

    A procedure utilizing the Gibbs-Duhem relation is used to extrapolate vapor pressures of supercooled HNO3 mixtures to 190 K. Values of A and B from the equation logP = A - B/T are presented for solutions between 0.20 and 0.25 mole fraction HNO3. In the stratosphere, if sufficient HNO3 vapor is present because it has not come into equilibrium with the nitric acid trihydrate, supercooled nitric acid solutions could condense at temperatures up to 1.5 + or - 0.8 K above the ice point.

  8. X-Ray Diffraction Study of the Internal Structure of Supercooled Water

    NASA Technical Reports Server (NTRS)

    Dorsch, Robert G.; Boyd, Bemrose

    1951-01-01

    A Bragg X-ray spectrometer equipped with a volume-sensitive Geiger counter and Soller slits and employing filtered molybdenum Ka radiation was used to obtain a set of diffracted intensity curves as a Punction of angle for supercooled water. Diffracted intensity curves in the temperature region of 21 to -16 C were obtained. The minimum between the two main diffraction peaks deepened continuously with lowering temperature, indicating a gradual change in the internal structure of the water. No discontinuity in this trend was noted at the melting point. The internal structure of supercooled water was concluded to become progressively more ice-like as the temperature is lowered.

  9. Enzyme kinetics in acoustically levitated droplets of supercooled water: a novel approach to cryoenzymology.

    PubMed

    Weis, David D; Nardozzi, Jonathan D

    2005-04-15

    The rate of the alkaline phosphatase-catalyzed hydrolysis of 4-methylumbelliferone phosphate was measured in acoustically levitated droplets of aqueous tris (50 mM) at pH 8.5 at 22 +/- 2 degrees C and in supercooled solution at -6 +/- 2 degrees C. At 22 degrees C, the rate of product formation was in excellent agreement with the rate observed in bulk solution in a cuvette, indicating that the acoustic levitation process does not alter the enzyme activity. The rate of the reaction decreased 6-fold in supercooled solution at -6 +/- 2 degrees C. The acoustic levitator apparatus is described in detail. PMID:15828793

  10. Structures and Dynamics of Glass-Forming Colloidal Liquids under Spherical Confinement

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Cheng, Xiang

    2016-03-01

    Recent theories predict that when a supercooled liquid approaches the glass transition, particle clusters with a special "amorphous order" nucleate within the liquid, which lead to static correlations dictating the dramatic slowdown of liquid relaxation. The prediction, however, has yet to be verified in 3D experiments. Here, we design a colloidal system, where particles are confined inside spherical cavities with an amorphous layer of particles pinned at the boundary. Using this novel system, we capture the amorphous-order particle clusters and demonstrate the development of a static correlation. Moreover, by investigating the dynamics of spherically confined samples, we reveal a profound influence of the static correlation on the relaxation of colloidal liquids. In analogy to glass-forming liquids with randomly pinned particles, we propose a simple relation for the change of the configurational entropy of confined colloidal liquids, which quantitatively explains our experimental findings and illustrates a divergent static length scale during the colloidal glass transition.