Sample records for water freezing point

  1. Effects of impurities on the freezing plateau of the triple point of water

    NASA Astrophysics Data System (ADS)

    Yan, X.; Zhang, J. T.; Duan, Y.; Wang, W.; Hao, X.

    2013-09-01

    The influence of impurities on the shape of the freezing curves of the triple point of water (TPW) in three small TPW cells was investigated using the freezing curve analysis method. We describe the procedure for preparing outer ice mantles in small TPW cells, for obtaining freezing plateaus, and for comparing the results between the old cell (s/n: 021) and the new cells (s/n: 001 and s/n: 008). The experimental results show that the maximum influence of impurities on the observed phase-transition temperature of water in the cell (s/n: 021) is approximately 0.2 mK below the peak temperature of the freezing plateau during freezing. Also, jagged temperature fluctuations were observed near the end of the freezing plateau in the old cell. However, these phenomena did not appear in the freezing plateaus of the new small cells. The equilibrium temperature realized with the old cell is 2.3 mK lower than that of the new cells, possibly due to excessive residual air. Therefore, assessing the effects of impurities on the TPW using an outer sheath method similar to that used in obtaining the fixed points of other metals is useful. Additionally, an estimated total mole fraction impurity concentration can be determined using Raoult's Law and the first cryoscopic constant for water.

  2. Cavitation in water under tension near the freezing point

    SciTech Connect

    Sosikov, V. A., E-mail: vaso@icp.ac.ru; Utkin, A. V.; Fortov, V. E. [Russian Academy of Sciences, Institute of Problems of Chemical Physics (Russian Federation)

    2008-05-15

    Experiments are reported on cavitation in water at an initial temperature of 0.7 deg. C under the dynamic tension created when a compression wave interacts with a free liquid surface. It is found that the tensile strength of water increases from 20 to 50 MPa as the strain rate is varied from 1.8 x 10{sup 4} to 5.2 x 10{sup 4} s{sup -1}. It is shown that the phase state of water obtained in experiments is in a double metastable region.

  3. 7.NS Comparing Freezing Points

    NSDL National Science Digital Library

    This is a task from the Illustrative Mathematics website that is one part of a complete illustration of the standard to which it is aligned. Each task has at least one solution and some commentary that addresses important asects of the task and its potential use. Here are the first few lines of the commentary for this task: Ocean water freezes at about $-2 \\frac12 ^\\circ C$. Fresh water freezes at $0 ^\\circ C$. Antifreeze, a liquid used in the radiators of cars, freezes at...

  4. When hot water freezes before cold

    E-print Network

    J. I. Katz

    2006-04-27

    I suggest that the origin of the Mpemba effect (the freezing of hot water before cold) is freezing-point depression by solutes, either gaseous or solid, whose solubility decreases with increasing temperature so that they are removed when water is heated. They are concentrated ahead of the freezing front by zone refining in water that has not been heated, reduce the temperature of the freezing front, and thereby reduce the temperature gradient and heat flux, slowing the progress of the front. I present a simple calculation of this effect, and suggest experiments to test this hypothesis.

  5. Freezing behaviour of microencapsulated water.

    PubMed

    Yamane, H; Ohshima, H; Kondo, T

    1992-01-01

    The freezing behaviour of water in polyurea microcapsules was studied through DSC (differential scanning calorimetry) and ESR (electron spin resonance) measurements under a non-equilibrium condition to show that supercooling of water becomes more noticeable with decreasing droplet size of the liquid. Thermodynamics of small systems was found applicable to analyse the experimental findings, even though the process of water freezing in the microcapsules was not of an equilibrium nature. PMID:1328582

  6. Device and method for determining freezing points

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, Balakrishnan (Inventor)

    1986-01-01

    A freezing point method and device (10) are disclosed. The method and device pertain to an inflection point technique for determining the freezing points of mixtures. In both the method and device (10), the mixture is cooled to a point below its anticipated freezing point and then warmed at a substantially linear rate. During the warming process, the rate of increase of temperature of the mixture is monitored by, for example, thermocouple (28) with the thermocouple output signal being amplified and differentiated by a differentiator (42). The rate of increase of temperature data are analyzed and a peak rate of increase of temperature is identified. In the preferred device (10) a computer (22) is utilized to analyze the rate of increase of temperature data following the warming process. Once the maximum rate of increase of temperature is identified, the corresponding temperature of the mixture is located and earmarked as being substantially equal to the freezing point of the mixture. In a preferred device (10), the computer (22), in addition to collecting the temperature and rate of change of temperature data, controls a programmable power supply (14) to provide a predetermined amount of cooling and warming current to thermoelectric modules (56).

  7. KEY COMPARISON: Final report on comparison COOMET.TK3: Regional comparisons of the national standards of temperature in the range from the triple point of water to the freezing temperature of zinc

    Microsoft Academic Search

    A. I. Pokhodun; A. G. Ivanova

    2008-01-01

    The COOMET.T-K3 comparison is the regional comparison of the defining fixed points realization in the range from the triple point of water to the freezing point of zinc. Four national metrology institutes---VNIIM (pilot), SMU, BelGIM and NNC IM---took part in the COOMET regional comparisons. At the first stage the cells of fixed points of the national metrology institutes were used

  8. Study of freezing-point depression of selected food extracts

    SciTech Connect

    Tanaka, Fumihiko [Kagoshima Univ. (Japan). Dept. of Agricultural Systems Engineering; Murata, Satoshi; Habara, Kazuhiro; Amaratunga, K.S.P. [Kyushu Univ., Fukuoka (Japan). Dept. of Agricultural Engineering

    1996-12-31

    The phenomenon of freezing-point depression that accompanies the solute concentration of selected food extracts was investigated to reveal the characteristics of solid-liquid phase equilibrium. The freezing curves of various food extracts did not exhibit ideal solution behavior in the higher concentration range. The experimental data were fitted to new freezing-point depression equations by the method of nonlinear least squares, and the results clearly indicated that the calculated freezing points at various concentrations were in good agreement with the experimental data. Furthermore, by using the determined parameters, the freezing ratio and the activation coefficient were derived.

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

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2010-01-01

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

  10. Freezing and Decorated Poisson Point Processes

    NASA Astrophysics Data System (ADS)

    Subag, Eliran; Zeitouni, Ofer

    2015-07-01

    The limiting extremal processes of the branching Brownian motion (BBM), the two-speed BBM, and the branching random walk are known to be randomly shifted decorated Poisson point processes (SDPPP). In the proofs of those results, the Laplace functional of the limiting extremal process is shown to satisfy for any nonzero, nonnegative, compactly supported, continuous function f, where is the shift operator, is a real number that depends on f, and g is a real function that is independent of f. We show that, under some assumptions, this property characterizes the structure of SDPPP. Moreover, when it holds, we show that g has to be a convolution of the Gumbel distribution with some measure. The above property of the Laplace functional is closely related to a `freezing phenomenon' that is expected to occur in a wide class of log-correlated fields, and which has played an important role in the analysis of various models. Our results shed light on this intriguing phenomenon and provide a natural tool for proving an SDPPP structure in these and other models.

  11. Realization of the Temperature Scale in the Range from 234.3 K (Hg Triple Point) to 1084.62°C (Cu Freezing Point) in Croatia

    NASA Astrophysics Data System (ADS)

    Zvizdic, Davor; Veliki, Tomislav; Grgec Bermanec, Lovorka

    2008-06-01

    This article describes the realization of the International Temperature Scale in the range from 234.3 K (mercury triple point) to 1084.62°C (copper freezing point) at the Laboratory for Process Measurement (LPM), Faculty of Mechanical Engineering and Naval Architecture (FSB), University of Zagreb. The system for the realization of the ITS-90 consists of the sealed fixed-point cells (mercury triple point, water triple point and gallium melting point) and the apparatus designed for the optimal realization of open fixed-point cells which include the gallium melting point, tin freezing point, zinc freezing point, aluminum freezing point, and copper freezing point. The maintenance of the open fixed-point cells is described, including the system for filling the cells with pure argon and for maintaining the pressure during the realization.

  12. Water’s size-dependent freezing to cubic ice

    Microsoft Academic Search

    G. P. Johari

    2005-01-01

    Water has been occasionally found to freeze to cubic ice. To investigate this occurrence thermodynamically, we use the known enthalpy and interfacial energy of hexagonal and cubic ices and calculate a critical radius rc of ?15 nm for a water droplet and a critical thickness ?c of ?10 nm for water’s flat film. Accordingly, water droplets smaller than 15 nm

  13. High-freezing-point fuels used for aviation turbine engines

    NASA Technical Reports Server (NTRS)

    Friedman, R.

    1979-01-01

    Broadened-specification aviation fuels could be produced from a greater fraction of crude source material with improvements in fuel supply and price. These fuels, particularly those with increased final boiling temperatures, would have higher freezing temperatures than current aviation turbine fuels. The higher-freezing-point fuels can be substituted in the majority of present commercial flights, since temperature data indicate that in-flight fuel temperatures are relatively mild. For the small but significant fraction of commercial flights where low fuel temperatures make higher freezing-point fuel use unacceptable, adaptations to the fuel or fuel system may be made to accommodate this fuel. Several techniques are discussed. Fuel heating is the most promising concept. One simple system design uses existing heat rejection from the fuel-lubricating oil cooler, another uses an engine-driven generator for electrical heating. Both systems offer advantages that outweigh the obvious penalties.

  14. An Equipment to Measure the Freezing Point of Soils under Higher Pressure

    NASA Astrophysics Data System (ADS)

    Wang, Dayan; Guan, Hui; Wen, Zhi; Ma, Wei

    2014-05-01

    Soil freezing point is the highest temperature at which ice can be presented in the system and soil can be referred to as frozen. The freezing temperature of soil is an important parameter for solving many practical problems in civil engineering, such as evaluation of soil freezing depth, prediction of soil heaving, force of soil suction, etc. However, as the freezing temperature is always affected by many factors like soil particle size, mineral composition, water content and the external pressure endured by soils, to measure soil freezing point is a rather difficult task until now, not to mention the soil suffering higher pressure. But recently, with the artificial freezing technology widely used in the excavation of deep underground space, the frozen wall thickness is a key factor to impact the security and stability of deep frozen wall. To determine the freeze wall thickness, the location of the freezing front must be determined firstly, which will deal with the determination of the soil freezing temperature. So how to measure the freezing temperature of soil suffering higher pressure is an important problem to be solved. This paper will introduce an equipment which was developed lately by State Key Laboratory of Frozen Soil Engineering to measure the freezing-point of soils under higher pressure. The equipment is consisted of cooling and keeping temperature system, temperature sensor and data collection system. By cooling and keeping temperature system, not only can we make the higher pressure soil sample's temperature drop to a discretionary minus temperature, but also keep it and reduce the heat exchange of soil sample with the outside. The temperature sensor is the key part to our measurement, which is featured by high precision and high sensitivity, what is more important is that the temperature sensor can work in a higher pressure condition. Moreover, the major benefit of this equipment is that the soil specimen's loads can be loaded by any microcomputer control electron universal testing machines. All of above mentioned advantages of this equipment ensures one to catch up the moment soil turns from the thawed state into ice and enable one to determine the freezing point experimentally by recording the temperature-time history (cooling curve) at particular points within the sample used for analysis. Therefore, this equipment has excellent characteristics such as compact construction, convenient operation, high reliability and the measuring accuracy. The authors would like to thank the following agents for their financial supports: the National Natural Science Foundation (No.41071048),Hundred Talent Young Scientists program of the Chinese Academy of Sciences granted to Dr. Zhi Wen.

  15. High freezing point fuels used for aviation turbine engines

    NASA Technical Reports Server (NTRS)

    Friedman, R.

    1979-01-01

    Broadened-specification aviation fuels could be produced from a greater fraction of crude source material with improvements in fuel supply and price. These fuels, particularly those with increased final boiling temperatures, would have higher freezing temperatures than current aviation turbine fuels. For the small but significant fraction of commercial flights where low fuel temperatures make higher freezing-point fuel use unacceptable, adaptations to the fuel or fuel system may be made to accommodate this fuel. Several techniques are discussed. Fuel heating is the most promising concept. One simple design uses existing heat rejection from the fuel-lubricating oil cooler, another uses an engine-driven generator for electrical heating.

  16. Chilled water coil freeze protection via internal drying

    SciTech Connect

    LaRocca, D.V. [Yale Univ. School of Medicine, New Haven, CT (United States). Building Services and Operations Dept.

    1997-12-01

    Winter lay-up for chilled water coils has been a problem for as long as there has been air conditioning. A frozen coil may be so seriously damaged that it must be replaced. Also, as the coil thaws, significant flooding of adjacent areas may result. Over the years, various methods of freeze protection have been used. These methods include using a glycol solution to lower the freezing point, blowing the coil clear with compressed air, or installing coils that incorporate freeze plugs in the coil design. Each of these methods has one or more significant drawbacks. A new approach, nicknamed ``The LaRocca Solution`` is a simple procedure. Air is blown continuously through the coils to ensure that they become completely dry and remain so. Instead of using a separate blower or air compressor to blow out the water, the supply fan itself is used. On most medium- and high-pressure HVAC systems, the static pressure produced by the supply fan is sufficient to overcome the internal resistance of the coil tubes. One simply configures the chilled water piping in a manner that permits the coils to be drained by gravity and then purged by the discharge of the fan. The fan does all the work.

  17. Immersion freezing of birch pollen washing water

    NASA Astrophysics Data System (ADS)

    Augustin, S.; Wex, H.; Niedermeier, D.; Pummer, B.; Grothe, H.; Hartmann, S.; Tomsche, L.; Clauss, T.; Voigtländer, J.; Ignatius, K.; Stratmann, F.

    2013-11-01

    Birch pollen grains are known to be ice nucleating active biological particles. The ice nucleating activity has previously been tracked down to biological macromolecules that can be easily extracted from the pollen grains in water. In the present study, we investigated the immersion freezing behavior of these ice nucleating active (INA) macromolecules. Therefore we measured the frozen fractions of particles generated from birch pollen washing water as a function of temperature at the Leipzig Aerosol Cloud Interaction Simulator (LACIS). Two different birch pollen samples were considered, with one originating from Sweden and one from the Czech Republic. For the Czech and Swedish birch pollen samples, freezing was observed to start at -19 and -17 °C, respectively. The fraction of frozen droplets increased for both samples down to -24 °C. Further cooling did not increase the frozen fractions any more. Instead, a plateau formed at frozen fractions below 1. This fact could be used to determine the amount of INA macromolecules in the droplets examined here, which in turn allowed for the determination of nucleation rates for single INA macromolecules. The main differences between the Swedish birch pollen and the Czech birch pollen were obvious in the temperature range between -17 and -24 °C. In this range, a second plateau region could be seen for Swedish birch pollen. As we assume INA macromolecules to be the reason for the ice nucleation, we concluded that birch pollen is able to produce at least two different types of INA macromolecules. We were able to derive parameterizations for the heterogeneous nucleation rates for both INA macromolecule types, using two different methods: a simple exponential fit and the Soccer ball model. With these parameterization methods we were able to describe the ice nucleation behavior of single INA macromolecules from both the Czech and the Swedish birch pollen.

  18. Hot water can freeze faster than cold?!?

    E-print Network

    Monwhea Jeng

    2005-12-29

    We review the Mpemba effect, where intially hot water freezes faster than initially cold water. While the effect appears impossible at first sight, it has been seen in numerous experiments, was reported on by Aristotle, Francis Bacon, and Descartes, and has been well-known as folklore around the world. It has a rich and fascinating history, which culminates in the dramatic story of the secondary school student, Erasto Mpemba, who reintroduced the effect to the twentieth century scientific community. The phenomenon, while simple to describe, is deceptively complex, and illustrates numerous important issues about the scientific method: the role of skepticism in scientific inquiry, the influence of theory on experiment and observation, the need for precision in the statement of a scientific hypothesis, and the nature of falsifiability. We survey proposed theoretical mechanisms for the Mpemba effect, and the results of modern experiments on the phenomenon. Studies of the observation that hot water pipes are more likely to burst than cold water pipes are also described.

  19. Promising freeze protection alternatives in solar domestic hot water systems

    Microsoft Academic Search

    1997-01-01

    Since the gains associated with solar thermal energy technologies are comparatively small in relation to the required capital investment, it is vital to maximize conversion efficiency. While providing the necessary function of freeze protection, the heat exchanger commonly included in solar domestic water heating systems represents a system inefficiency. This thesis explores two alternate methods of providing freeze protection without

  20. Photomicrographic Investigation of Spontaneous Freezing Temperatures of Supercooled Water Droplets

    NASA Technical Reports Server (NTRS)

    Dorsch, R. G.; Hacker, P. T.

    1950-01-01

    A photomicrographic technique for investigating eupercooled. water droplets has been devised and. used. to determine the spontaneous freezing temperatures of eupercooled. water droplets of the size ordinarily found. in the atmosphere. The freezing temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous freezing temperature decreased with decrease in the size of the droplets. The effect of size on the spontaneous freezing temperature was particularly marked below 60 microns. Frequency-distribution curves of the spontaneous freezing temperatures observed for droplets of a given size were obtained. Although no droplet froze at a temperature above 20 0 F, all droplets melted at 32 F. Results obtained with a copper support did not differ essentially from those obtained with a platinum surface.

  1. Water's size-dependent freezing to cubic ice

    Microsoft Academic Search

    G. P. Johari

    2005-01-01

    Water has been occasionally found to freeze to cubic ice. To investigate this occurrence thermodynamically, we use the known enthalpy and interfacial energy of hexagonal and cubic ices and calculate a critical radius rc of ~15 nm for a water droplet and a critical thickness deltac of ~10 nm for water's flat film. Accordingly, water droplets smaller than 15 nm

  2. Universality of tip singularity formation in freezing water drops.

    PubMed

    Marín, A G; Enríquez, O R; Brunet, P; Colinet, P; Snoeijer, J H

    2014-08-01

    A drop of water deposited on a cold plate freezes into an ice drop with a pointy tip. While this phenomenon clearly finds its origin in the expansion of water upon freezing, a quantitative description of the tip singularity has remained elusive. Here we demonstrate how the geometry of the freezing front, determined by heat transfer considerations, is crucial for the tip formation. We perform systematic measurements of the angles of the conical tip, and reveal the dynamics of the solidification front in a Hele-Shaw geometry. It is found that the cone angle is independent of substrate temperature and wetting angle, suggesting a universal, self-similar mechanism that does not depend on the rate of solidification. We propose a model for the freezing front and derive resulting tip angles analytically, in good agreement with the experiments. PMID:25126922

  3. Realization of the Temperature Scale in the Range from 234.3 K (Hg Triple Point) to 1084.62°C (Cu Freezing Point) in Croatia

    Microsoft Academic Search

    Davor Zvizdic; Tomislav Veliki; Lovorka Grgec Bermanec

    2008-01-01

    This article describes the realization of the International Temperature Scale in the range from 234.3 K (mercury triple point)\\u000a to 1084.62°C (copper freezing point) at the Laboratory for Process Measurement (LPM), Faculty of Mechanical Engineering and\\u000a Naval Architecture (FSB), University of Zagreb. The system for the realization of the ITS-90 consists of the sealed fixed-point\\u000a cells (mercury triple point, water triple

  4. Freezing Point of Milk: A Natural Way to Understand Colligative Properties

    ERIC Educational Resources Information Center

    Novo, Mercedes; Reija, Belen; Al-Soufi, Wajih

    2007-01-01

    A laboratory experiment is presented in which the freezing point depression is analyzed using milk as solution. The nature of milk as a mixture of different solutes makes it a suitable probe to learn about colligative properties. The first part of the experiment illustrates the analytical use of freezing point measurements to control milk quality,…

  5. Units of freezing of deep supercooled water in woody xylem.

    PubMed

    Hong, S G; Sucoff, E

    1980-07-01

    The low temperature exotherms (LTE) of 1-year-old twigs of Haralson apple (Malus pumila Mill.), shagbark hickory (Carya ovata [Mill.] K. Koch), green ash (Fraxinus pennsylvanica Marsh), honey locust (Gleditsia triacanthos L.), American chestnut (Castanea dentata [Marsh] Borkh.), and red oak (Quercus rubra L.) were determined by differential thermal analysis (DTA). In one type of experiment freezing during a DTA experiment was halted for up to 2.5 hours after part of the supercooled water had frozen at temperatures between -25 and -42 C. Upon resumption of cooling the freezing started within 2 C of the stopping temperature. In a second type of experiment living and dead cells were microscopically observed in the same ray after partial freezing in the DTA apparatus. In another experiment, the LTE persisted even after tangential and radial sectioning of the twig to 0.13 millimeters. In a final experiment the LTE of a single multiseriate ray of red oak had the same shape as the LTE of wood with many uniseriate rays.These experiments confirm that the deep supercooled water in woody xylem or pith freezes in numerous independent events over a span of as much as 20 C. The units which freeze in an event are single cells or small groups of cells. Ice grows very slowly if at all from these units, and water moves very slowly from unfrozen cells to frozen ones. Deep supercooling of ray parenchyma does not require an intact ray. PMID:16661390

  6. FREEZING WATER CLEANING A POSSIBLE IMPROVEMENT IN SRF CAVITY RINSING*

    E-print Network

    ERL 10-3 FREEZING WATER CLEANING ­ A POSSIBLE IMPROVEMENT IN SRF CAVITY RINSING* Valery Shemelin rinsing (HPR) is a necessary stage of SRF cavity preparation [1] because it provides cleaner, field the traditional HPR are at hand in any SRF lab, a simple cooling down of the cavity before rinsing can

  7. Design and evaluation of aircraft heat source systems for use with high-freezing point fuels

    NASA Technical Reports Server (NTRS)

    Pasion, A. J.

    1979-01-01

    The objectives were the design, performance and economic analyses of practical aircraft fuel heating systems that would permit the use of high freezing-point fuels on long-range aircraft. Two hypothetical hydrocarbon fuels with freezing points of -29 C and -18 C were used to represent the variation from current day jet fuels. A Boeing 747-200 with JT9D-7/7A engines was used as the baseline aircraft. A 9300 Km mission was used as the mission length from which the heat requirements to maintain the fuel above its freezing point was based.

  8. Experimental research of "microcable in a microconduct" system stability to effect of freezing water

    NASA Astrophysics Data System (ADS)

    Andreev, Vladimir A.; Burdin, Vladimir A.; Nikulina, Tatiana G.; Alekhin, Ivan N.; Gavryushin, Sergey A.; Nikulin, Aleksey G.; Praporshchikov, Denis E.

    2011-12-01

    Results of experimental researches of "optical microcable in a microduct" system stability to effect of freezing water are presented. It is shown this system is steadier to water freezing in comparison to lighten optical cable in protective polymer tube.

  9. Enthalpy relaxation of freeze concentrated sucrose-water glass.

    PubMed

    Inoue, Chiharu; Suzuki, Toru

    2006-02-01

    The enthalpy relaxation of freeze concentrated sucrose-water glass was investigated using 40% sucrose, differential scanning calorimetry (DSC) with isothermal ageing for 1-6 days at various temperatures (-70, -65, -60, and -55 degrees C). The enthalpy relaxation was observed as an endothermic peak superimposed on the endothermic step-wise change due to the glass transition around -47 degrees C. The enthalpy relaxation was found to increase with ageing time and temperature. An 80% sucrose glass was also investigated at ageing temperatures of -60 and -65 degrees C, and this material exhibited a similar glass transition and enthalpy relaxation to that observed with the frozen 40% sucrose solution. The calculated activation energy of the enthalpy relaxation of the sucrose-water glass was smaller than that reported for pure sucrose. These results suggest that the freeze concentrated sucrose-water glass could have a higher molecular mobility and less stability than pure sucrose glass. PMID:16321366

  10. Freeze Dried Zn-DNA: Magnetism Dominated by Water Molecules

    NASA Astrophysics Data System (ADS)

    Kumeta, Tsubasa; Sakamoto, Hirokazu; Mizoguchi, Kenji

    2014-08-01

    Magnetic behaviors in freeze dried DNA complexes with Zn ions (FD-Zn-DNA) are reported. Dehydrated Zn-DNA was prepared from pure Zn-DNA by a freeze drying procedure. Complete dehydration of Zn-DNA by the freeze drying induces an irreversible structural change and produces one ? electron spin at each base pair of FD-Zn-DNA. Magnetic behaviors essential to the ? electron spins are markedly changed by introducing water molecules in FD-Zn-DNA. In the dehydrated FD-Zn-DNA, the paramagnetism of the ? spin system is totally suppressed because of the spin singlet ground state caused by the strong off-site Coulomb repulsion V, which is larger than the on-site Coulomb repulsion U. In contrast, the hydrated FD-Zn-DNA carries large Pauli-like temperature-independent paramagnetism, whose magnitude corresponds to the ?-band width of ?0.24 eV. A possible mechanism of the ? electron spin creation is proposed. As a subsidiary effect of the freeze drying procedure, the nonlinear paramagnetism saturating below 0.1 T is observed in both DNA and Zn-DNA. The nonlinear paramagnetism disappears after the hydration of the sample. On the basis of the magnitude of the saturation magnetization, it is suggested that the origin of the nonlinear paramagnetism is the magnetic impurities in DNA.

  11. Evaluation of methods for rapid determination of freezing point of aviation fuels

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, B.

    1982-01-01

    Methods for identification of the more promising concepts for the development of a portable instrument to rapidly determine the freezing point of aviation fuels are described. The evaluation process consisted of: (1) collection of information on techniques previously used for the determination of the freezing point, (2) screening and selection of these techniques for further evaluation of their suitability in a portable unit for rapid measurement, and (3) an extensive experimental evaluation of the selected techniques and a final selection of the most promising technique. Test apparatuses employing differential thermal analysis and the change in optical transparency during phase change were evaluated and tested. A technique similar to differential thermal analysis using no reference fuel was investigated. In this method, the freezing point was obtained by digitizing the data and locating the point of inflection. Results obtained using this technique compare well with those obtained elsewhere using different techniques. A conceptual design of a portable instrument incorporating this technique is presented.

  12. Note: equation of state and the freezing point in the hard-sphere model.

    PubMed

    Robles, Miguel; López de Haro, Mariano; Santos, Andrés

    2014-04-01

    The merits of different analytical equations of state for the hard-sphere system with respect to the recently computed high-accuracy value of the freezing-point packing fraction are assessed. It is found that the Carnahan-Starling-Kolafa and the branch-point approximant equations of state yield the best performance. PMID:24712819

  13. Note: Equation of state and the freezing point in the hard-sphere model

    NASA Astrophysics Data System (ADS)

    Robles, Miguel; López de Haro, Mariano; Santos, Andrés

    2014-04-01

    The merits of different analytical equations of state for the hard-sphere system with respect to the recently computed high-accuracy value of the freezing-point packing fraction are assessed. It is found that the Carnahan-Starling-Kolafa and the branch-point approximant equations of state yield the best performance.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Primary biological particles can act as efficient ice nuclei (IN) by initiating freezing events at temperatures warmer than the homogenous freezing temperature [1, 2]. For example, pollen grain particles can trigger freezing events at temperatures as warm as -5 °C in the contact freezing mode [3]. More recently pollen residues, which are released by washing pollen grains in water, were also observed to act as efficient IN in the immersion mode [4, 5]. In this study we developed a new cold electrodynamic balance (CEDB) system and investigated the freezing properties of single particles of supercooled pollen washing water (SPWW). The EDB technique allows for a contact free measurement of freezing events. The phase of the particle (liquid or frozen solid) can be distinguished via measuring the Mie scattering signal from the particle. Furthermore the size of liquid (spherical) particles can be determined. The freezing events are characterized through the loss of the regular Mie scattering signal from the levitated droplet as it changes state from liquid to a frozen solid. The statistical freezing probabilities of SPWW were obtained in the temperature range: -15 to -40 °C. Each temperature measurement point consists of the analysis of 30-100 droplets. Preliminary conclusions are that SPWW is IN active in the immersion mode. Further discussion will focus on the temperature range of the IN activity, the important variables (other than temperature) for IN activity, other likely modes of IN activity, and the implications of these results in terms of the atmospheric relevance of SPWW. This study was supported by the NERC. We acknowledge Professor Jonathan Reid and James Davis from the University of Bristol for providing information of the design of the warm EDB system. References: [1] Möhler, O., et al. (2007) Biogeosciences, 4, 1059-1071. [2] Prenni, A. J., et al. (2009) Nat. Geosci., 2, 401-404. [3] Diehl, K., et al. (2002) Atmos. Res., 61, 125-133. [4] Pummer, B. G., et al. (2012) Atmos. Chem. Phys., 12, 2541-2550. [5] Augustin, S., et al. (2013) Atmos. Chem. Phys., 13, 10989-11003.

  15. A search for the Mpemba effect: When hot water freezes faster then cold water James D. Brownridge

    E-print Network

    Suzuki, Masatsugu

    A search for the Mpemba effect: When hot water freezes faster then cold water James D. Brownridge 6000 Binghamton, New York 13902-6000, USA Abstract: An explanation for why hot water will sometime freeze more rapidly than cold water is offered. Two specimens of water from the same source will often

  16. Ice slurry cooling research: Microscale study of ice particles characteristics, role of freezing point depressant, and influence on slurry fluidity

    Microsoft Academic Search

    K. Hayashi; K. Kasza

    2000-01-01

    The influences of freezing-point-depressants on ice slurry characteristics in the form of ice slurry fluidity and on the microscale ice particle features are studied. The results identify microscale features of ice particles such as surface roughness that greatly influence slurry fluidity that are altered favorably by the use of a freezing point depressant. The engineering of a workable and efficient

  17. Thermodynamical effects accompanied freezing of two water layers separated by sea ice sheet

    NASA Astrophysics Data System (ADS)

    Bogorodsky, Petr; Marchenko, Aleksey

    2014-05-01

    The process of melt pond freezing is very important for generation of sea ice cover thermodynamic and mass balance during winterperiod. However, due to significant difficulties of field measurements the available data of model estimations still have no instrumental confirmation. In May 2009 the authors carried out laboratory experiment on freezing of limited water volume in the University Centre in Svalbard ice tank. In the course of experiment fresh water layer of 27.5 cm thickness at freezing point poured on the 24 cm sea ice layer was cooled during 50 hours at the temperature -10º C and then once again during 60 hours at -20º C. For revealing process typical characteristics the data of continuous measurements of temperature and salinity in different phases were compared with data of numerical computations obtained with thermodynamic model which was formulated in the frames of 1-D equation system (infinite extension of water freezing layer) and adapted to laboratory conditions. The known surprise of the experiment became proximity of calculated and measured estimates of process dynamics that confirmed the adequacy of the problem mathematical statement (excluding probably process finale stage). This effect can be explained by formation of cracks on the upper layer of ice at sharp decreases of air temperature, which temporary compensated hydrostatic pressure growth during freezing of closed water volume. Another compensated mechanism can be migration of brine through the lower layer of ice under influence of vertical pressure gradient and also rejection of gas dissolved in water which increased its compressibility. During 110 hours cooling thickness of water layer between ice layers reduced approximately to 2 cm. According to computations this layer is not chilled completely but keeps as thin brine interlayer within ice body whose thickness (about units of mm) is determined by temperature fluctuations of cooled surface. Nevertheless, despite good coincidence of experimental and model estimates the question of existence of liquid phase under actual conditions is still open and can be clarified in a continuous laboratory experiment. This work was supported by Russian Foundation for Basic Research (Project # 14-05-00677).

  18. The impact of soil freezing/thawing processes on water and energy balances

    NASA Astrophysics Data System (ADS)

    Zhang, Xia; Sun, Shufen

    2011-01-01

    A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes affect water and energy balances in seasonal frozen soil. Simulation results of soil liquid water content and temperature using soil model with and without the inclusion of freezing and thawing processes are evaluated against observations at the Rosemount field station. By comparing the simulated water and heat fluxes of the two cases, the role of phase change processes in the water and energy balances is analyzed. Soil freezing induces upward water flow towards the freezing front and increases soil water content in the upper soil layer. In particular, soil ice obviously prevents and delays the infiltration during rain at Rosemount. In addition, soil freezing/thawing processes alter the partitioning of surface energy fluxes and lead the soil to release more sensible heat into the atmosphere during freezing periods.

  19. Relationship between freezing tolerance and shoot water relations of western red cedar.

    PubMed

    Grossnickle, S C

    1992-10-01

    Freezing tolerance and shoot water relations parameters of western red cedar (Thuja plicata Donn) seedlings were measured every 2 weeks from October 1989 to April 1990. Freezing tolerance, measured by freeze-induced electrolyte leakage, showed seasonal shifts in the temperature causing 50% foliage electrolyte leakage (LT(50)). The LT(50) value was -4 degrees C in October, it decreased to -20 degrees C in February and then increased to -6 degrees C in April. The foliage index of injury at -10 degrees C (II(-10)) also showed seasonal shifts from a high of 98% in October to a low of 18% in February followed by an increase to 82% in April. Osmotic potentials at saturation (Psi(s(sat))) and turgor loss point (Psi(s(tlp))) were, respectively, -1.07 and -1.26 MPa in October, -1.57 and -2.43 MPa in January, and -1.04 and -1.86 MPa in April. Dry weight fraction (DWF) increased and symplastic volume at full turgor (V(o)) decreased during the fall-winter acclimation phase, whereas DWF decreased and V(o) increased during the late winter-spring deacclimation phase. Relationships between seasonal patterns of freezing tolerance and shoot water relations parameters showed that LT(50) and II(-10) decreased linearly as Psi(s(tlp)) and V(o) decreased and DWF increased. There was no discernible difference in the relationship during fall acclimation or spring deacclimation. The freezing dehydration index at -10 degrees C (FDI(-10)) declined from 0.69 in November to 0.41 in February and increased to 0.56 in April. The value of II(-10) decreased linearly as FDI(-10) decreased, although a measurement made on actively growing spring foliage did not fit this relationship. The results indicate that seasonal changes in freezing tolerance of western red cedar are partially due to changes in tissue water content, symplastic volume, passive osmotic adjustment and FDI(-10). PMID:14969948

  20. Metabolic Activity of Permafrost Bacteria below the Freezing Point

    PubMed Central

    Rivkina, E. M.; Friedmann, E. I.; McKay, C. P.; Gilichinsky, D. A.

    2000-01-01

    Metabolic activity was measured in the laboratory at temperatures between 5 and ?20°C on the basis of incorporation of 14C-labeled acetate into lipids by samples of a natural population of bacteria from Siberian permafrost (permanently frozen soil). Incorporation followed a sigmoidal pattern similar to growth curves. At all temperatures, the log phase was followed, within 200 to 350 days, by a stationary phase, which was monitored until the 550th day of activity. The minimum doubling times ranged from 1 day (5°C) to 20 days (?10°C) to ca. 160 days (?20°C). The curves reached the stationary phase at different levels, depending on the incubation temperature. We suggest that the stationary phase, which is generally considered to be reached when the availability of nutrients becomes limiting, was brought on under our conditions by the formation of diffusion barriers in the thin layers of unfrozen water known to be present in permafrost soils, the thickness of which depends on temperature. PMID:10919774

  1. Metabolic activity of permafrost bacteria below the freezing point

    NASA Technical Reports Server (NTRS)

    Rivkina, E. M.; Friedmann, E. I.; McKay, C. P.; Gilichinsky, D. A.

    2000-01-01

    Metabolic activity was measured in the laboratory at temperatures between 5 and -20 degrees C on the basis of incorporation of (14)C-labeled acetate into lipids by samples of a natural population of bacteria from Siberian permafrost (permanently frozen soil). Incorporation followed a sigmoidal pattern similar to growth curves. At all temperatures, the log phase was followed, within 200 to 350 days, by a stationary phase, which was monitored until the 550th day of activity. The minimum doubling times ranged from 1 day (5 degrees C) to 20 days (-10 degrees C) to ca. 160 days (-20 degrees C). The curves reached the stationary phase at different levels, depending on the incubation temperature. We suggest that the stationary phase, which is generally considered to be reached when the availability of nutrients becomes limiting, was brought on under our conditions by the formation of diffusion barriers in the thin layers of unfrozen water known to be present in permafrost soils, the thickness of which depends on temperature.

  2. A Four-Zone Furnace for Realization of Silver and Gold Freezing Points

    NASA Astrophysics Data System (ADS)

    Ripple, D. C.; Garrity, K. M.; Meyer, C. W.

    2003-09-01

    Recently, the Thermocouple Calibration Laboratory at the National Institute of Standards and Technology has used sodium heat-pipe furnaces for the realization of ITS-90 freezing points of aluminum, silver, and gold. When using a fixed-point cell mounted in a long silica-glass tube that extends to ambient temperature at the top of the furnace, we have observed significant thermal gradients along the well of the fixed-point cell, with the top of the well up to 0.1 K colder than the bottom. Furthermore, the heat-pipe lifetime is limited when used at the gold point (1064.18 °C) for more than a few hundred hours. To address these problems, we have designed and built a four-zone furnace based on a temperature-controlled, graphite isothermal block, suspended inside a three-zone tube furnace. The three-zone furnace is of a commercial design. The graphite block is enclosed in an alloy 600 (Inconel) can, allowing the graphite to be maintained in an argon atmosphere. The argon pressure is maintained at one atmosphere at all temperatures, thereby greatly reducing the stress on the can. Heaters in intimate contact with the can allow temperature control of the fourth inner zone to high accuracy. In this paper, the measured thermal stability and uniformity achieved with this furnace are presented. We also give results of test freezes of a silver freezing-point cell.

  3. Mechanism of freezing of water in contact with mesoporous silicas MCM-41, SBA-15 and SBA-16: role of boundary water of pore outlets in freezing.

    PubMed

    Kittaka, Shigeharu; Ueda, Yuki; Fujisaki, Fumika; Iiyama, Taku; Yamaguchi, Toshio

    2011-10-14

    The freezing mechanism of water contacted with mesoporous silicas with uniform pore shapes, both cylindrical and cagelike, was studied by thermodynamic and structural analyses with differential scanning calorimetry (DSC) and X-ray diffraction (XRD) together with adsorption measurements. In the DSC data extra exothermic peaks were found at around 230 K for water confined in SBA-15, in addition to that due to the freezing of pore water. These peaks are most likely to be ascribed to the freezing of water present over the micropore and/or mesopore outlets of coronas in SBA-15. Freezing of water confined in SBA-16 was systematically analysed by DSC with changing the pore size. The freezing temperature was found to be around 232 K, close to the homogeneous nucleation temperature of bulk water, independent of the pore size when the pore diameter (d) < 7.0 nm. Water confined in the cagelike pores of SBA-16 is probably surrounded by a water layer (boundary water) at the outlets of channels to interconnect the pores and of fine corona-like pores, which is similar to that present at the outlet of cylindrical pores in MCM-41 and of cylindrical channels in SBA-15. The presence of the boundary water would be a key for water in SBA-16 to freeze at the homogeneous nucleation temperature. This phenomenon is similar to those well known for water droplets in oil and water droplets of clouds in the sky. The XRD data showed that the cubic ice I(c) was formed in SBA-16 as previously found in SBA-15 when d < 8.0 nm. PMID:21879058

  4. Multiple Freezing Points as a Test for Viability of Plant Stems in the Determination of Frost Hardiness 1

    PubMed Central

    McLeester, R. C.; Weiser, C. J.; Hall, T. C.

    1969-01-01

    A technique is presented for a simple, rapid, and reliable means of determining the viability of plant tissue subjected to freezing temperatures. Freezing curves of excised stems of Cornus stolonifera Michx., and several other genera were studied. Tissue temperature was recorded during freezing of plant stem sections. The heat of crystallization deflected the resultant freezing curves at points where tissue froze. Living stem sections of all genera studied revealed 2 freezing points, while dead tissue exhibited only 1. The influence of variables such as moisture content, sample size, thermocouple placement, and cooling rate on freezing curves was analyzed. Stem samples wrapped in moisture-proof film with a thermocouple inserted into the pith were frozen to a predetermined test temperature, thawed, and subjected to a second freezing cycle. The presence or absence of 2 freezing points in the second freezing cycle was used as a criterion for establishing viability. The results were immediately available and identical to results from regrowth tests which took about 20 days. PMID:16657031

  5. Triple Point of Water Cells

    Microsoft Academic Search

    Xumo Li; Deming Chen

    An improved technique for manufacturing triple point of water (TPW) cells is reported. The im- provements focus primarily on two points: (1) keeping the gas pressure in the cell as low as pos- sible, and (2) achieving the highest possible water purity in the cell. Two cells manufactured with the new technique were certificated at NIST, and the differences from

  6. The freezing process of continuously sprayed water droplets on the superhydrophobic silicone acrylate resin coating surface

    NASA Astrophysics Data System (ADS)

    Hu, Jianlin; Xu, Ke; Wu, Yao; Lan, Binhuan; Jiang, Xingliang; Shu, Lichun

    2014-10-01

    This study conducted experiments on freezing process of water droplets on glass slides covered with superhydrophobic coatings under the continuous water spray condition in the artificial climatic chamber which could simulate low temperature and high humidity environments. The freezing mechanism and freezing time of water droplets under the condition of continuous spray were observed by the microscope and were compared with those of the single static droplet. Then, differences of freezing process between continuously sprayed droplets and single static droplet were analyzed. Furthermore, the effects of static contact angle (CA), contact angle hysteresis (CAH) and roughness of the superhydrophobic coating surface on the freezing time of continuously sprayed droplets were explored. Results show that the freezing process of the continuously sprayed droplets on the superhydrophobic coating started with the homogeneous nucleation at gas-liquid interfaces. In addition, the temperature difference between the location near the solid-liquid interface and the location near the gas-liquid interface was the key factor that influenced the ice crystallization mechanism of water droplets. Moreover, with the larger CA, the smaller CAH and the greater roughness of the surface, droplets were more likely to roll down the surface and the freezing duration on the surface was delayed. Based on the findings, continuous water spray is suggested in the anti-icing superhydrophobic coatings research.

  7. THE URANIUM HEXAFLUORIDE-HYDROGEN FLUORIDE FREEZING POINT CURVE AND ITS APPLICATION TO A METHOD OF ANALYSIS

    Microsoft Academic Search

    R. J. Wertz; W. D. Hedge

    1960-01-01

    The freezing point curve for the system uranium hexafluoride--hydrogen ; fluoride was determined over the range 0.0 to 0.6 wt% hydrogen fluoride and is ; represented by the equation wt% HF = 0.0841 DELTA t + 0.1020 DELTA t² -- ; 0.1046 DELTA t³ + 0.0363 DELTA t⁴ where DELTA t is the depression ; of the freezing point of

  8. Spray freeze-dried porous microparticles of a poorly water-soluble drug for respiratory delivery.

    PubMed

    Niwa, Toshiyuki; Mizutani, Daisuke; Danjo, Kazumi

    2012-01-01

    Particles of poorly water-soluble drugs were prepared to develop a dry powder inhaler (DPI). Spray freeze-drying (SFD) technique using a four-fluid nozzle (4N), which has been developed by authors, was applied in this research. Ciclosporin and mannitol were used as a poorly water-soluble model drug and a dissolution-enhanced carrier, respectively. The organic solution of ciclosporin and aqueous solution of mannitol were separately and simultaneously atomized through the 4N, and the two solutions were collided with each other at the tip of the nozzle edge. The spray mists were immediately frozen in liquid nitrogen to form a suspension. Then, the iced droplets were freeze-dried to prepare the composite particles of the drug and carrier. tert-Butyl alcohol (t-BuOH) was used as the organic spray solvent due to its relatively high freezing point. The resultant composite particles with varying drug content were characterized depending on their morphological and physicochemical properties. The particles contained amorphous ciclosporin and ?-crystalline mannitol. The characteristic porous structure of SFD particles potentially contributed to their good aerodynamic performance. A series of particles with a similar size distribution and different drug content revealed that the incorporation of mannitol successfully improved the cohesive behavior of ciclosporin, leading to enhanced aerosol dispersion. The dissolution test method using low-volume medium was newly established to simulate the release process from particles deposited on the surface of the bronchus and pulmonary mucosa. The composite with hydrophilic mannitol dramatically improved the in vitro dissolution behavior of ciclosporin in combination with the porous structure of SFD particles. PMID:22790820

  9. Freezing, Drying, and\\/or Vitrification of Membrane– Solute–Water Systems

    Microsoft Academic Search

    Joe Wolfe; Gary Bryant

    1999-01-01

    Membranes are often damaged by freezing and\\/or dehydration, and this damage may be reduced by solutes. In many cases, these phenomena can be explained by the physical behavior of membrane–solute–water systems. Both solutes and membranes reduce the freezing temperature of water, although their effects are not simply additive. The dehydration of membranes induces large mechanical stresses in the membranes. These

  10. Water freezes differently on positively and negatively charged surfaces of pyroelectric materials.

    PubMed

    Ehre, David; Lavert, Etay; Lahav, Meir; Lubomirsky, Igor

    2010-02-01

    Although ice melts and water freezes under equilibrium conditions at 0 degrees C, water can be supercooled under homogeneous conditions in a clean environment down to -40 degrees C without freezing. The influence of the electric field on the freezing temperature of supercooled water (electrofreezing) is of topical importance in the living and inanimate worlds. We report that positively charged surfaces of pyroelectric LiTaO3 crystals and SrTiO3 thin films promote ice nucleation, whereas the same surfaces when negatively charged reduce the freezing temperature. Accordingly, droplets of water cooled down on a negatively charged LiTaO3 surface and remaining liquid at -11 degrees C freeze immediately when this surface is heated to -8 degrees C, as a result of the replacement of the negative surface charge by a positive one. Furthermore, powder x-ray diffraction studies demonstrated that the freezing on the positively charged surface starts at the solid/water interface, whereas on a negatively charged surface, ice nucleation starts at the air/water interface. PMID:20133568

  11. Development of modulated optical transmission system to determinate the cloud and freezing points in biofuels

    NASA Astrophysics Data System (ADS)

    Jaramillo-Ochoa, Liliana; Ramirez-Gutierrez, Cristian F.; Sánchez-Moguel, Alonso; Acosta-Osorio, Andrés; Rodriguez-Garcia, Mario E.

    2015-01-01

    This work is focused in the development of a modulated optical transmission system with temperature control to determine the thermal properties of biodiesels such as the cloud and freezing points. This system is able to determine these properties in real time without relying on the operator skills as indicated in the American Society for Testing Materials (ASTM) norms. Thanks to the modulation of the incident laser, the noise of the signal is reduced and two information channels are generated: amplitude and phase. Lasers with different wavelengths can be used in this system but the sample under study must have optical absorption at the wavelength of the laser.

  12. Development of modulated optical transmission system to determinate the cloud and freezing points in biofuels.

    PubMed

    Jaramillo-Ochoa, Liliana; Ramirez-Gutierrez, Cristian F; Sánchez-Moguel, Alonso; Acosta-Osorio, Andrés; Rodriguez-Garcia, Mario E

    2015-01-01

    This work is focused in the development of a modulated optical transmission system with temperature control to determine the thermal properties of biodiesels such as the cloud and freezing points. This system is able to determine these properties in real time without relying on the operator skills as indicated in the American Society for Testing Materials (ASTM) norms. Thanks to the modulation of the incident laser, the noise of the signal is reduced and two information channels are generated: amplitude and phase. Lasers with different wavelengths can be used in this system but the sample under study must have optical absorption at the wavelength of the laser. PMID:25638112

  13. The Triple Point of Water

    Microsoft Academic Search

    Worden Waring

    1943-01-01

    (1) A common error in text-books on physical chemistry is pointed out. It is hoped that the correct value for the triple point temperature, +.0098 degrees C, will be given in new books and in succeeding editions of the books surveyed above. (2) Inconsistencies in the vapor pressure values for ice and for liquid water near 0 degrees C are

  14. A comparative study of freeze-thaw processes for conditioning wastewater and water treatment sludges

    SciTech Connect

    Trahern, P.G.

    1989-01-01

    This research effort involved the application of indirect- and direct-contact, freeze-thaw conditioning techniques for improving the dewatering characteristics of both waste water and water treatment sludges. Sludges tested included waste activated sludge, primary sewage sludge, waste activated/primary sewage sludge mixtures and alum sludge. The direct-freeze methods examined were the use of a secondary refrigerant (butane) evaporated in the sludge and the use of gas hydrate or clathrate formation by addition of Freon 12 under appropriate temperature and pressure conditions. Sludges were also frozen solid using indirect freezing methods, thawed and tested for comparative purposes. Particle size distribution and floc density measurements were used to determine changes in particle characteristics; specific resistance values and dewatered dry solids concentration were used to assess dewatering characteristics. Results of direct and indirect-contact, freeze-thaw conditioning were compared to the effects of polymer conditioning. The results indicated that direct-freeze methods do not appear technically or economically competitive with currently accepted conditioning methods. The superior results obtained with the indirect-contact, freeze-thaw process when compared to the direct-contact processes suggested that the extent and rate of freezing may greatly influence the particle characteristics of the conditioned sludge, and thus its dewatering characteristics.

  15. Aqueous propylene-glycol concentrations for the freeze protection of thermosyphon solar energy water heaters

    Microsoft Academic Search

    B. Norton; J. E. J. Edmonds

    1991-01-01

    Using a validated dynamic simulation model, the thermal performance of an indirect thermosyphon solar energy water heater was examined. The heat transfer fluids employed were aqueous solutions of propylene glycol. The effect of varying the glycol concentration on the hot water output and efficacy of freeze protection was determined for a specific pattern of hot water withdrawal and weather for

  16. How Circulation of Water Affects Freezing in Ponds

    ERIC Educational Resources Information Center

    Moreau, Theresa; Lamontagne, Robert; Letzring, Daniel

    2007-01-01

    One means of preventing the top of a pond from freezing involves running a circulating pump near the bottom to agitate the surface and expose it to air throughout the winter months. This phenomenon is similar to that of the flowing of streams in subzero temperatures and to the running of taps to prevent pipe bursts in winter. All of these cases…

  17. Journal of the Physical Society of Japan Freeze Dried Zn-DNA: Magnetism Dominated by Water Molecules

    E-print Network

    Mizoguchi, Kenji

    Journal of the Physical Society of Japan Freeze Dried Zn-DNA: Magnetism Dominated by Water University, Hachioji, Tokyo 192-0397, Japan Magnetic behaviors in freeze dried DNA complexes with Zn ions (FD-Zn-DNA) are reported. Dehydrated Zn-DNA was prepared from pure Zn-DNA by a freeze drying procedure. Com- plete

  18. In situ freeze-capturing of fracture water using cryogenic coring

    SciTech Connect

    Su, Grace W.; Wang, Joseph S.Y.; Zacny, Kris

    2004-01-29

    Current methods do not allow for sampling of in situ water from unsaturated fractures in low-moisture environments. A novel cryogenic coring technique based on the method developed by Simon and Cooper (1996) is used to collect in situ water in unsaturated fractures. This method uses liquid nitrogen as the drilling fluid, which can freeze the fracture water in place while coring. Laboratory experiments are conducted to demonstrate that water in an unsaturated fracture can be frozen and collected using cryogenic coring.

  19. Units of Freezing of Deep Supercooled Water in Woody Xylem 1

    PubMed Central

    Hong, Sung-Gak; Sucoff, Edward

    1980-01-01

    The low temperature exotherms (LTE) of 1-year-old twigs of Haralson apple (Malus pumila Mill.), shagbark hickory (Carya ovata [Mill.] K. Koch), green ash (Fraxinus pennsylvanica Marsh), honey locust (Gleditsia triacanthos L.), American chestnut (Castanea dentata [Marsh] Borkh.), and red oak (Quercus rubra L.) were determined by differential thermal analysis (DTA). In one type of experiment freezing during a DTA experiment was halted for up to 2.5 hours after part of the supercooled water had frozen at temperatures between ?25 and ?42 C. Upon resumption of cooling the freezing started within 2 C of the stopping temperature. In a second type of experiment living and dead cells were microscopically observed in the same ray after partial freezing in the DTA apparatus. In another experiment, the LTE persisted even after tangential and radial sectioning of the twig to 0.13 millimeters. In a final experiment the LTE of a single multiseriate ray of red oak had the same shape as the LTE of wood with many uniseriate rays. These experiments confirm that the deep supercooled water in woody xylem or pith freezes in numerous independent events over a span of as much as 20 C. The units which freeze in an event are single cells or small groups of cells. Ice grows very slowly if at all from these units, and water moves very slowly from unfrozen cells to frozen ones. Deep supercooling of ray parenchyma does not require an intact ray. Images PMID:16661390

  20. Aqueous propylene-glycol concentrations for the freeze protection of thermosyphon solar energy water heaters

    SciTech Connect

    Norton, B. (Univ. of Ulster, Newtownabbey (Ireland)); Edmonds, J.E.J. (Energy Control Consultants Ltd., Buckinhamshire (England))

    1991-01-01

    Using a validated dynamic simulation model, the thermal performance of an indirect thermosyphon solar energy water heater was examined. The heat transfer fluids employed were aqueous solutions of propylene glycol. The effect of varying the glycol concentration on the hot water output and efficacy of freeze protection was determined for a specific pattern of hot water withdrawal and weather for the temperature maritime climate of London, England. The heat output is compared with that of a drain-down direct system.

  1. Can Propagation of Gas Bubbles Lead to Detached Solidification? Experiments on Freezing of Water

    NASA Technical Reports Server (NTRS)

    Wang, Yazhen; Regel, Liya; Wilcox, William R.

    2002-01-01

    A vertical Bridgman-Stockbarger apparatus was used to directionally solidify water upward, in the hope that detached solidification would evolve from gas bubbles forming on the wall. A large contact angle of the water on the ampoule wall and a high solubility of the dissolved gas caused gas bubbles or tubes to form only at the ampoule wall, and not in the interior. Gas tubes were often nearly periodically spaced around the ampoule wall, with a spacing that increased with ampoule diameter and decreased with freezing rate. The width of the gas tubes was nearly independent of the ampoule diameter and freezing rate. A high degree of detachment was obtained with a rough, nonwetting coating on the ampoule wall, but full detachment was not achieved. This indicates that detachment does not occur by propagation of a single gas bubble around the periphery of the freezing interface. The convection near the freezing interface influenced gas bubble formation, and was outward for a concave freezing interface and inward for a convex interface.

  2. Estimating the influence of impurities on the freezing point of tin

    NASA Astrophysics Data System (ADS)

    Fellmuth, Bernd; Hill, Kenneth D.

    2006-02-01

    The sum of individual estimates (SIE) and the overall maximum estimate (OME) are two methods recommended to estimate the influence of impurities on the temperatures of the liquid-solid phase transformations of high-purity substances. The methods are discussed starting with the basic crystallographic facts, and their application is demonstrated in detail by applying them to the freezing point of tin as a first example. The SIE method leads to a temperature correction with a corresponding uncertainty while the OME method yields only an uncertainty that is, perhaps not unexpectedly, larger than that of the SIE approach. The necessary sensitivity coefficients (derivatives of the liquidus lines) are tabulated, together with the equilibrium distribution coefficients. Other than the necessity of obtaining a complete elemental analysis of the fixed-point material using glow discharge mass spectrometry (or other suitable techniques), there remain no technical barriers to adopting the preferred SIE method. While the use of the method, and particularly the application of a temperature correction to account for the impurity influence, requires a paradigm shift within the thermometry community, improved interoperability and harmonization of approach are highly desirable goals. The SIE approach maximizes the application of scientific knowledge and represents the best chance of achieving these common goals.

  3. Sea water desalination by dynamic layer melt crystallization: Parametric study of the freezing and sweating steps

    NASA Astrophysics Data System (ADS)

    Rich, Anouar; Mandri, Youssef; Mangin, Denis; Rivoire, Alain; Abderafi, Souad; Bebon, Christine; Semlali, Naoual; Klein, Jean-Paul; Bounahmidi, Tijani; Bouhaouss, Ahmed; Veesler, Stéphane

    2012-03-01

    This work aims at developing a dynamic layer crystallizer operated batchwise, for freezing desalination of sea water. The experiments were performed with water/NaCl solutions and with samples of sea water from Nice, Rabat and Marseille. The pilot crystallizer consists of a cooled tube immersed in a cylindrical double jacketed tank. The solution is poured into the tank and the crystallization takes place on the external surface of the tube, by applying a cooling ramp in the tube. The solution is agitated by air bubbling. The whole process involves the freezing step, leading to the crystallization of the ice layer and the sweating step, which consists of purifying in depth the ice layer by melting the impure zones. A parametric study on the effect of the operating parameters has allowed quantifying the role of the different key parameters of the freezing and sweating steps. Three experiments allowed reaching salinities lower than 0.5 g/kg, satisfying the standards of drinking water. The duration of the whole process dropped to only 8 h (5 h for freezing and 3 h for sweating), with a yield of sweating equal to about 50%, provided severe conditions were applied for sweating. Higher yields required longer times. Overall, the results show the feasibility of the technique.

  4. The impact of soil freezing\\/thawing processes on water and energy balances

    Microsoft Academic Search

    Xia Zhang; Shufen Sun

    2011-01-01

    A frozen soil parameterization coupling of thermal and hydrological processes is used to investigate how frozen soil processes\\u000a affect water and energy balances in seasonal frozen soil. Simulation results of soil liquid water content and temperature\\u000a using soil model with and without the inclusion of freezing and thawing processes are evaluated against observations at the\\u000a Rosemount field station. By comparing

  5. Ice slurry cooling research: Microscale study of ice particles characteristics, role of freezing point depressant, and influence on slurry fluidity

    SciTech Connect

    Hayashi, K.; Kasza, K.

    2000-05-03

    The influences of freezing-point-depressants on ice slurry characteristics in the form of ice slurry fluidity and on the microscale ice particle features are studied. The results identify microscale features of ice particles such as surface roughness that greatly influence slurry fluidity that are altered favorably by the use of a freezing point depressant. The engineering of a workable and efficient ice slurry cooling system depends very strongly on the characteristics of the individual ice particles in the slurry and, in turn, on the method of ice production. Findings from this study provide guidance on the fluidity and handleability of slurry produced by several methods currently under development and already many achieved.

  6. Accuracy of two osmometers on standard samples: electrical impedance technique and freezing point depression technique

    NASA Astrophysics Data System (ADS)

    García-Resúa, Carlos; Pena-Verdeal, Hugo; Miñones, Mercedes; Gilino, Jorge; Giraldez, Maria J.; Yebra-Pimentel, Eva

    2013-11-01

    High tear fluid osmolarity is a feature common to all types of dry eye. This study was designed to establish the accuracy of two osmometers, a freezing point depression osmometer (Fiske 110) and an electrical impedance osmometer (TearLab™) by using standard samples. To assess the accuracy of the measurements provided by the two instruments we used 5 solutions of known osmolarity/osmolality; 50, 290 and 850 mOsm/kg and 292 and 338 mOsm/L. Fiske 110 is designed to be used in samples of 20 ?l, so measurements were made on 1:9, 1:4, 1:1 and 1:0 dilutions of the standards. Tear Lab is addressed to be used in tear film and only a sample of 0.05 ?l is required, so no dilutions were employed. Due to the smaller measurement range of the TearLab, the 50 and 850 mOsm/kg standards were not included. 20 measurements per standard sample were used and differences with the reference value was analysed by one sample t-test. Fiske 110 showed that osmolarity measurements differed statistically from standard values except those recorded for 290 mOsm/kg standard diluted 1:1 (p = 0.309), the 292 mOsm/L H2O sample (1:1) and 338 mOsm/L H2O standard (1:4). The more diluted the sample, the higher the error rate. For the TearLab measurements, one-sample t-test indicated that all determinations differed from the theoretical values (p = 0.001), though differences were always small. For undiluted solutions, Fiske 110 shows similar performance than TearLab. However, for the diluted standards, Fiske 110 worsens.

  7. NMR studies of water compartmentation in carrot parenchyma tissue during drying and freezing

    Microsoft Academic Search

    B. P. Hills; K. P. Nott

    1999-01-01

    An analysis is presented of the effect of drying and freezing on the distribution and pulse spacing dependence of water proton\\u000a transverse relaxation times in carrot parenchyma tissue. The relaxation behaviour can be interpreted by treating the effects\\u000a of changing subcellular morphology with a numerical cell model and combining this with a two-site proton exchange model to\\u000a take account of

  8. Watershed water circle dynamics during long term farmland conversion in freeze-thawing area

    NASA Astrophysics Data System (ADS)

    Ouyang, Wei; Bing, Liu; Huang, Haobo; Hao, Fanghua; Hao, Zengchao

    2015-04-01

    Water resource is increasingly scarce in agricultural watershed under the pressure of socio-economic development. Long term land use conversion and freeze-thawing process posed additional characteristics to the water cycle. The semi-distributed hydrologic model Soil and Water Assessment Tool (SWAT) was employed for surface runoff, evaporation, and percolation simulations in freeze-thawing agricultural watershed. The interpreted five terms of land use data over three decades demonstrated that the percentage of the farmland area of the whole watershed increased from 23.5% to 62.1% and about half of dryland shifted to the paddy land in the recent ten years. The validated SWAT simulation showed that the spatial distribution of the surface runoff volume and the watershed averaged value increased 60 mm. The correlations of precipitation with surface runoff at monthly and yearly scales decreased from 0.8-0.9 to 0.6-0.7 respectively, which highlighted the impact of land use change over the surface runoff. The watershed evaporation was lower under the freeze-thawing condition, which increased from 363.7 mm to 418.5 mm over three decades. The field monitoring recorded the decreasing groundwater level, which was coincided with the expanding area of the paddy land. The watershed precipitation did not varied intensively in the whole simulation period (CV ? 0.01), but the percolation varied as the result of the cultivation disturbance on soil properties. The analysis showed that the expanding paddy land decreased the groundwater level at 0.17 m/yr during 1997 and 2012, which posed new challenge on regional water management. The evapotranspiration in the extreme size of paddy land was relatively small and the groundwater level also decreased relatively slow. These characteristics demonstrated the impact of freeze-thawing on the water cycle. The proposed method can be used as an effective tool for quantitative prediction of irrigation water amount and identify the impact of land use change on the water cycle at freeze-thawing agricultural watershed.

  9. Fabrication of two-dimensional nanosheets via water freezing expansion exfoliation.

    PubMed

    Li, Chen; Wang, Tailin; Wu, Yongzhong; Ma, Fukun; Zhao, Gang; Hao, Xiaopeng

    2014-12-12

    Layered materials, if exfoliated effectively, will exhibit several unique properties, offering great potential for diverse applications. To this end, in this study, we develop a novel, universal, and environmentally friendly method named as 'water freezing expansion exfoliation' for producing two-dimensional nanosheets. This method exploits the expansion in the volume of water upon freezing. When the water freezing expansion condition is reproduced in layered materials, the layers exfoliate to overcome the van der Waals force between them. The expansion process is performed by repeated cycling between 4 °C and -20 °C to effectively exfoliate layered materials of graphite, hexagonal boron nitride (h-BN), MoS2 and WS2. Systematic characterization of the samples thus obtained using electron microscopy and optical studies substantiate the formation of thin flakes (graphene, h-BN, MoS2, and WS2 nanosheets). The method demonstrated in this study is cost-effective and does not demand sophisticated equipment and stringent high temperature conditions. Given this general applicability, this method holds great promise for exfoliating layered materials that are sensitive to elevated temperature. PMID:25414167

  10. Fabrication of two-dimensional nanosheets via water freezing expansion exfoliation

    NASA Astrophysics Data System (ADS)

    Li, Chen; Wang, Tailin; Wu, Yongzhong; Ma, Fukun; Zhao, Gang; Hao, Xiaopeng

    2014-12-01

    Layered materials, if exfoliated effectively, will exhibit several unique properties, offering great potential for diverse applications. To this end, in this study, we develop a novel, universal, and environmentally friendly method named as ‘water freezing expansion exfoliation’ for producing two-dimensional nanosheets. This method exploits the expansion in the volume of water upon freezing. When the water freezing expansion condition is reproduced in layered materials, the layers exfoliate to overcome the van der Waals force between them. The expansion process is performed by repeated cycling between 4 °C and ?20 °C to effectively exfoliate layered materials of graphite, hexagonal boron nitride (h-BN), MoS2 and WS2. Systematic characterization of the samples thus obtained using electron microscopy and optical studies substantiate the formation of thin flakes (graphene, h-BN, MoS2, and WS2 nanosheets). The method demonstrated in this study is cost-effective and does not demand sophisticated equipment and stringent high temperature conditions. Given this general applicability, this method holds great promise for exfoliating layered materials that are sensitive to elevated temperature.

  11. The effect of water content, cooling rate, and growth temperature on the freezing temperature of 4 Tillandsia species 

    E-print Network

    Hagar, Christopher Flint

    1990-01-01

    THE EFFECT OF WATER CONTENT, COOLING RATE, AND GROWTH TEMPERATURE ON THE FREEZING TEMPERATURE OF 4 TILLANDSIA SPECIES A Thesis by CHRISTOPHER FLINT HAGAR Submitted to the Office of Graduate Studies of Texas A&M University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1990 Major Subject: Horticulture THE EFFECT OF WATER CONTENT g COOLING RATE AND GROWTH TEMPERATURE ON THE FREEZING TEMPERATURE OF 4 TILLANDSIA SPECIES A Thesis...

  12. Evaluation of the freeze-thaw\\/evaporation process for the treatment of produced waters. Final report, August 1992August 1996

    Microsoft Academic Search

    J. E. Boysen; K. L. Walker; J. L. Mefford; J. R. Kirsch; J. A. Harju

    1996-01-01

    The use of freeze-crystallization is becoming increasingly acknowledged as a low-cost, energy-efficient method for purifying contaminated water. The natural freezing process can be coupled with natural evaporative processes to treat oil and gas produced waters year round in regions where subfreezing temperatures seasonally occur. The climates typical of Colorado`s San Juan Basin and eastern slope, as well as the oil

  13. Supercooling Point Plasticity During Cold Storage in the Freeze-tolerant Sugarbeet Root Maggot Tetanops myopaeformis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sugarbeet root maggot, Tetanops myopaeformis (Röder), overwinters as a freeze-tolerant 3rd instar larva. While most larvae are thought to overwinter for only one year, some may exhibit prolonged diapause in the field. In the laboratory, they can live for over five years using a combination of ...

  14. Supercooling and freezing processes in nanoconfined water by time-resolved optical Kerr effect spectroscopy

    E-print Network

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

    2014-08-06

    Using heterodyne-detected optical Kerr effect (HD-OKE) measurements, we investigate the vibrational dynamics and the structural relaxation of water nanoconfined in Vycor porous silica samples (pore size $\\simeq~4~nm$ ) at different levels of hydration and temperatures. At low level of hydration, corresponding to two complete superficial water layers, no freezing occurs and water remains mobile at all the investigated temperatures with dynamic features similar, but not equal, to the bulk water. The fully hydrated sample shows formation of ice at about 248 K, this process does not involve all the contained water; a part of it remains in a supercooled phase. The structural relaxation times measured from the decay of the time-dependent HD-OKE signal shows temperature dependence largely affected by the hydration level; the low frequency ($\

  15. Ponds Freeze in Winter -- Why Doesn't the Ocean?

    NSDL National Science Digital Library

    New England Aquarium

    2011-01-01

    In this activity, learners explore how salt water freezes in comparison to fresh water. Use this experiment to consider how pond animals survive cold winters in comparison to animals that live in the ocean. This resource includes information about freezing points as well as examples of how different animals respond to the winter cold.

  16. Molecular Dynamics Study of Freezing Point and Solid-Liquid Interfacial Free Energy of Stockmayer Fluids

    SciTech Connect

    Wang, J. [University of Nebraska, Lincoln; Apte, Pankaj [Indian Institute of Technology, Kanpur; Morris, James R [ORNL; Zeng, X.C. [University of Nebraska, Lincoln

    2013-01-01

    Freezing temperatures of Stockmayer fluids with different dipolar strength at zero pressure are estimated and computed using three independent molecular-dynamics (MD) simulation methods, namely, the superheating-undercooling method, the constant-pressure and constant-temperature (NPT) two phase coexistence method, and the constant-pressure and constant-enthalpy (NPH) coexistence method. The best estimate of the freezing temperature (in reduced unit) for the Stockmayer (SM) fluid with a reduced dipole moment is 0.656 0.001, 0.726 0.002 and 0.835 0.005, respectively. The freezing temperature increases with the dipolar strength. The solid-liquid interfacial free energies of the (111), (110) and (100) interface are calculated for the first time using two independent methods, namely, the cleaving-wall method and the interfacial fluctuation method. Both methods predict that the interfacial free energy increases with the dipole moment. Although the interfacial fluctuation method suggests a weaker interfacial anisotropy, particularly for strongly dipolar SM fluids, both methods predicted the same trend of interfacial anisotropy, that is, .

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  18. Measurement of water-soluble arsenic species in freeze-dried marine animal tissues by microwave-assisted extraction and HPLC-ICP-MS

    E-print Network

    Canberra, University of

    Measurement of water-soluble arsenic species in freeze-dried marine animal tissues by microwave-soluble arsenic in freeze-dried marine animal tissues. The optimum microwave-assisted conditions were three-assisted extraction procedure to identify and quantify arsenic species in freeze-dried marine animal tissues

  19. AgRISTARS: Early warning and crop condition assessment. Plant cover, soil temperature, freeze, water stress, and evapotranspiration conditions

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L. (principal investigator); Nixon, P. R.; Gausman, H. W.; Namken, L. N.; Leamer, R. W.; Richardson, A. J.

    1981-01-01

    Emissive (10.5 to 12.5 microns) and reflective (0.55 to 1.1 microns) data for ten day scenes and infrared data for six night scenes of southern Texas were analyzed for plant cover, soil temperature, freeze, water stress, and evapotranspiration. Heat capacity mapping mission radiometric temperatures were: within 2 C of dewpoint temperatures, significantly correlated with variables important in evapotranspiration, and related to freeze severity and planting depth soil temperatures.

  20. Traveling water waves with point vortices

    E-print Network

    Kristoffer Varholm

    2015-03-20

    We construct small-amplitude solitary traveling gravity-capillary water waves with a finite number of point vortices along a vertical line, on finite depth. This is done using a local bifurcation argument. The properties of the resulting waves are also examined: We find that they depend significantly on the position of the point vortices in the water column.

  1. MOST CURRENT WATER QUALITY STANDARDS - POINT EVENTS

    EPA Science Inventory

    State Water Quality Standards' Designated Uses for river segments, lakes, and estuaries. Most current Water Quality Standards coded onto route.rch (Transport and Coastline Reach) feature of the National Hydrography Dataset (NHD) to create NHD - Point Events. Point events are...

  2. Ice nucleation of Snomax® particles below water vapor saturation: immersion freezing in concentrated solution droplets

    NASA Astrophysics Data System (ADS)

    Wex, Heike; Kanji, Zamin A.; Boose, Yvonne; Beyer, Alexander; Henning, Silvia; Augustin-Bauditz, Stefanie

    2015-04-01

    Heterogeneous ice nucleation has received an increasing amount of interest in the past years, as it initiates the ice phase in mixed phase clouds (MPCs) and, to some extent, also in cirrus clouds. The presence of ice influences cloud radiative properties and, for mixed phase clouds, also the formation of precipitation. Immersion freezing is thought to be the most important mechanism through which ice formation could take place in MPCs. Here, we examine the ice nucleation activity of biological ice nucleating particles (INP) derived from bacteria, namely, particles generated from Snomax® suspensions, both above and below water vapor saturation. During a measurement campaign in Leipzig, ice nucleation measurements were conducted with PINC (Portable Ice Nucleus Counter, Chou et al., 2011) and LACIS (Leipzig Aerosol Cloud Interaction Simulator, see e.g. Wex et al., 2014a). Immersion freezing measurements from PINC and LACIS were in agreement in the temperature regime for which both instruments operate reliably. Here, we will show that measurements done below water vapour saturation and above the deliquescence relative humidity of the Snomax® particles follow what would be expected for immersion freezing in concentrated solutions, similar to what was suggested for coated kaolinite particles in Wex et al. (2014b). Additionally, some measurements reported in the literature that were done in the water vapour sub-saturated regime will be evaluated based on the assumption made above, showing that at least some of the ice nucleation which previously was ascribed to deposition ice nucleation rather follows the behavior of immersion freezing in concentrated solutions. Literature: Chou, C., O. Stetzer, E. Weingartner, Z. Juranyi, Z. A. Kanji, and U. Lohmann (2011), Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps, Atmos. Chem. Phys., 11(10), 4725-4738, doi:10.5194/acp-11-4725-2011. Wex, H. et al. (2014a) Intercomparing different devices for the investigation of ice nucleating particles using Snomax as test substance, Atmos. Chem. Phys. Discuss. (accepted for ACP), 14, 22321-22384, 2014. Wex, H., P. J. DeMott, Y. Tobo, S. Hartmann, M. Rösch, T. Clauss, L. Tomsche, D. Niedermeier, and F. Stratmann (2014b), Kaolinite particles as ice nuclei: learning from the use of different kaolinite samples and different coatings, Atmos. Chem. Phys., 14, doi:10.5194/acp-14-5529-2014.

  3. Freezing of sessile water droplets on surfaces with various roughness and wettability

    NASA Astrophysics Data System (ADS)

    Hao, Pengfei; Lv, Cunjing; Zhang, Xiwen

    2014-04-01

    This paper focus on the freezing delay time and the freezing time of sessile droplet on smooth, micro-structured and micro/nano-structured surfaces, and the whole freezing process are comparatively studied. The freezing delay time of the smooth surfaces with roughness smaller than the size of the critical ice nuclei is found to be much longer than superhydrophobic surfaces with hierarchical structures. Experimental data and theoretical analysis show that the surface roughness plays a very crucial role in nucleation. The freezing delay time could not be extended further on rough surface with more superhydrophobic for sessile droplet. In addition, decreased roughness can increase the free energy barrier for heterogeneous nucleation, result in significant freezing delay. On the contrary, the freezing time from the start of nucleation to the completion of freezing increases with the contact angle. In addition, surfaces with hierarchical roughness are found to have the longest freezing time.

  4. Dielectric relaxation of water below the melting point: the effect of inner pressure

    E-print Network

    Angulo-Sherman, Abril

    2013-01-01

    Despite water is the most studied substance in the Earth, it is not completely understood why its structural and dynamical properties give rise to some anomalous behaviors. Interesting properties emerge when experiments at low temperatures and/or high pressures, are performed. Here we report dielectric measurements of cold water under constrained conditions, i.e. water that below the melting point can not freeze. The inner pressure shifts the {\\alpha} relaxation peak to similar frequencies as seen in ice Ih. Also, when we reach the triple point at 251 K, ice III seems to form. As far as we know, this via to obtain such crystalline phase has not been observed.

  5. Dielectric relaxation of water below the melting point: the effect of inner pressure

    E-print Network

    Abril Angulo-Sherman; Hilda Mercado-Uribe

    2013-08-16

    Despite water is the most studied substance in the Earth, it is not completely understood why its structural and dynamical properties give rise to some anomalous behaviors. Interesting properties emerge when experiments at low temperatures and/or high pressures, are performed. Here we report dielectric measurements of cold water under constrained conditions, i.e. water that below the melting point can not freeze. The inner pressure shifts the {\\alpha} relaxation peak to similar frequencies as seen in ice Ih. Also, when we reach the triple point at 251 K, ice III seems to form. As far as we know, this via to obtain such crystalline phase has not been observed.

  6. The influence of residual water on the secondary structure and crystallinity of freeze-dried fibrinogen.

    PubMed

    Wahl, Verena; Scheibelhofer, Otto; Roessl, Ulrich; Leitgeb, Stefan; De Beer, Thomas; Khinast, Johannes

    2015-04-30

    The purpose of this work was to investigate the influence of water content on the secondary structure of a freeze-dried protein (fibrinogen) after a storage period of two weeks. To that end, attenuated reflectance Fourier transformed infrared (ATR-FTIR) and Raman spectra were generated and evaluated and the crystalline state of the fibrinogen bulks was determined via X-ray diffraction. First, a PCA (principal component analysis) of the spectral data was performed. While the ?-helix and ?-turn contents were increasing with the increasing water content, the ?-sheet content was decreasing. A partial least squares (PLS) model was developed to correlate the mid-infrared and Raman spectral changes with the degree of crystallinity. The obtained R(2) value of 0.953 confirmed a correlation between changes in the secondary structure and crystallinity of the samples. The results demonstrated that the combined ATR-FTIR and Raman approach could be used to predict the crystalline state in freeze-dried fibrinogen products. PMID:25701629

  7. Field observations of slush ice generated during freeze-up in arctic coastal waters

    USGS Publications Warehouse

    Reimnitz, E.; Kempema, E.W.

    1987-01-01

    In some years, large volumes of slush ice charged with sediment are generated from frazil crystals in the shallow Beaufort Sea during strong storms at the time of freeze-up. Such events terminate the navigation season, and because of accompanying hostile conditions, little is known about the processes acting. The water-saturated slush ice, which may reach a thickness of 4 m, exists for only a few days before freezing from the surface downward arrests further wave motion or pancake ice forms. Movements of small vessels and divers in the slush ice occurs only in phase with passing waves, producing compression and rarefaction, and internal pressure pulses. Where in contact with the seafloor, the agitated slush ice moves cobble-size material, generates large sediment ripples, and may possibly produce a flat rampart observed on the arctic shoreface in some years. Processes charging the slush ice with as much as 1000 m3 km-2 of sediment remain uncertain, but our field observations rule out previously proposed filtration from turbid waters as a likely mechanism. Sedimentary particles apparently are only trapped in the interstices of the slush ice rather than being held by adhesion, since wave-related internal pressure oscillations result in downward particle movement and cleansing of the slush ice. This loss of sediment explains the typical downward increase in sediment concentration in that part of the fast-ice canopy composed largely of frazil ice. The congealing slush ice in coastal water does not become fast ice until grounded ridges are formed in the stamukhi zone, one to two months after freeze-up begins. During this period of new-ice mobility, long-range sediment transport occurs. The sediment load held by the fast-ice canopy in the area between the Colville and Sagavanirktok River deltas in the winter of 1978-1979 was 16 times larger than the yearly river input to the same area. This sediment most likely was rafted from Canada, more than 400 km to the east, during a brief time period in the previous fall. Ocean turbulence is greatly reduced while the congealing slush ice drifts about. Therefore, new ice then forming in intervening open-water areas is clean. These events explain the patchy appearance of the fast ice after the summer snowmelt. More work on the important phenomena reported here is needed to close a major gap in the knowledge of the arctic marine environment. ?? 1987.

  8. Neutron diffraction study of water freezing on aircraft engine combustor soot.

    PubMed

    Tishkova, V; Demirdjian, B; Ferry, D; Johnson, M

    2011-12-14

    The study of the formation of condensation trails and cirrus clouds on aircraft emitted soot particles is important because of its possible effects on climate. In the present work we studied the freezing of water on aircraft engine combustor (AEC) soot particles under conditions of pressure and temperature similar to the upper troposphere. The microstructure of the AEC soot was found to be heterogeneous containing both primary particles of soot and metallic impurities (Fe, Cu, and Al). We also observed various surface functional groups such as oxygen-containing groups, including sulfate ions, that can act as active sites for water adsorption. Here we studied the formation of ice on the AEC soot particles by using neutron diffraction. We found that for low amount of adsorbed water, cooling even up to 215 K did not lead to the formation of hexagonal ice. Whereas, larger amount of adsorbed water led to the coexistence of liquid water (or amorphous ice) and hexagonal ice (I(h)); 60% of the adsorbed water was in the form of ice I(h) at 255 K. Annealing of the system led to the improvement of the crystal quality of hexagonal ice crystals as demonstrated from neutron diffraction. PMID:21996755

  9. Exploration of Impinging Water Spray Heat Transfer at System Pressures Near the Triple Point

    NASA Technical Reports Server (NTRS)

    Golliher, Eric L.; Yao, Shi-Chune

    2013-01-01

    The heat transfer of a water spray impinging upon a surface in a very low pressure environment is of interest to cooling of space vehicles during launch and re-entry, and to industrial processes where flash evaporation occurs. At very low pressure, the process occurs near the triple point of water, and there exists a transient multiphase transport problem of ice, water and water vapor. At the impingement location, there are three heat transfer mechanisms: evaporation, freezing and sublimation. A preliminary heat transfer model was developed to explore the interaction of these mechanisms at the surface and within the spray.

  10. Water sorption properties, molecular mobility and probiotic survival in freeze dried protein-carbohydrate matrices.

    PubMed

    Hoobin, Pamela; Burgar, Iko; Zhu, ShouChuang; Ying, DanYang; Sanguansri, Luz; Augustin, Mary Ann

    2013-09-01

    The moisture uptake and molecular mobility of freeze-dried powders containing whey protein isolate-carbohydrate matrices (1WPI:2maltodextrin; 1WPI:1maltodextrin:1d-glucose; and 1WPI:1maltodextrin:1l-glucose) and encapsulated Lactobacillus rhamnosus GG (LGG) in these matrices were investigated at 25 °C and 33% and 70% relative humidity (RH). The inactivation rate constant for probiotics in freeze-dried matrices were positively correlated (R(2) = 0.98) to moisture uptake and molecular mobility measured by NMR relaxometry. The stability of probiotics in glassy protein-carbohydrate matrices was dependent on the composition of the matrix. The partial substitution of maltodextrin with glucose (d- or l-) which improved microbial survival at 33% RH was related to the reduced molecular mobility and lower water uptake of the matrix. This study suggests that moisture uptake properties and molecular mobility of the matrix composition, as opposed to the relative humidity of the environment, are better determinants of probiotic viability during storage. Dynamic vapour sorption and NMR relaxometry are promising tools to assist in the selection of protein-carbohydrate matrices for enhancing probiotic viability during storage. PMID:23851914

  11. Visualization of Fuel Cell Water Transport and Performance Characterization under Freezing Conditions

    SciTech Connect

    Kandlikar, S.G.; Lu, Z.; Rao, N.; Sergi, J.; Rath, C.; Dade, C.; Trabold, T.; Owejan, J.; Gagliardo, J.; Allen, J.; Yassar, R.S.; Medici, E.; Herescu, A.

    2010-05-30

    In this program, Rochester Institute of Technology (RIT), General Motors (GM) and Michigan Technological University (MTU) have focused on fundamental studies that address water transport, accumulation and mitigation processes in the gas diffusion layer and flow field channels of the bipolar plate. These studies have been conducted with a particular emphasis on understanding the key transport phenomena which control fuel cell operation under freezing conditions. Technical accomplishments are listed below: • Demonstrated that shutdown air purge is controlled predominantly by the water carrying capacity of the purge stream and the most practical means of reducing the purge time and energy is to reduce the volume of liquid water present in the fuel cell at shutdown. The GDL thermal conductivity has been identified as an important parameter to dictate water accumulation within a GDL. • Found that under the normal shutdown conditions most of the GDL-level water accumulation occurs on the anode side and that the mass transport resistance of the membrane electrode assembly (MEA) thus plays a critically important role in understanding and optimizing purge. • Identified two-phase flow patterns (slug, film and mist flow) in flow field channel, established the features of each pattern, and created a flow pattern map to characterize the two-phase flow in GDL/channel combination. • Implemented changes to the baseline channel surface energy and GDL materials and evaluated their performance with the ex situ multi-channel experiments. It was found that the hydrophilic channel (contact angle ? ? 10?) facilitates the removal of liquid water by capillary effects and by reducing water accumulation at the channel exit. It was also found that GDL without MPL promotes film flow and shifts the slug-to-film flow transition to lower air flow rates, compared with the case of GDL with MPL. • Identified a new mechanism of water transport through GDLs based on Haines jump mechanism. The breakdown and redevelopment of the water paths in GDLs lead to an intermittent water drainage behavior, which is characterized by dynamic capillary pressure and changing of breakthrough location. MPL was found to not only limit the number of water entry locations into the GDL (thus drastically reducing water saturation), but also stabilizes the water paths (or morphology). • Simultaneously visualized the water transport on cathode and anode channels of an operating fuel cell. It was found that under relatively dry hydrogen/air conditions at lower temperatures, the cathode channels display a similar flow pattern map to the ex-situ experiments under similar conditions. Liquid water on the anode side is more likely formed via condensation of water vapor which is transported through the anode GDL. • Investigated the water percolation through the GDL with pseudo-Hele-Shaw experiments and simulated the capillary-driven two-phase flow inside gas diffusion media, with the pore size distributions being modeled by using Weibull distribution functions. The effect of the inclusion of the microporous layer in the fuel cell assembly was explored numerically. • Developed and validated a simple, reliable computational tool for predicting liquid water transport in GDLs. • Developed a new method of determining the pore size distribution in GDL using scanning electron microscope (SEM) image processing, which allows for separate characterization of GDL wetting properties and pore size distribution. • Determined the effect of surface wettability and channel cross section and bend dihedral on liquid holdup in fuel cell flow channels. A major thrust of this research program has been the development of an optimal combination of materials, design features and cell operating conditions that achieve a water management strategy which facilitates fuel cell operation under freezing conditions. Based on our various findings, we have made the final recommendation relative to GDL materials, bipolar design and surface properties, and the combination of materials, design featur

  12. Realization of the triple point of water

    Microsoft Academic Search

    J A Ferguson

    1970-01-01

    A method of making triple point of water cells has been developed. The water is purified using ion-exchange techniques followed by vacuum sublimation, and the cell is filled under vacuum. Measurements have shown the cells produced in this way to be of a consistently high standard. The technique described keeps the ice mantle in good condition for a month or

  13. Fish With Nature's Anti-freeze

    NSDL National Science Digital Library

    Using this material, students will discover that under special experimental conditions, fish have been observed functioning in ice-free cold salt water at a temperature of -6 degrees Centigrade. Research has found that these fish have eight types of anti-freeze molecules which bathe the interior surface of their skin, acting as a barrier to ice propagating in from outside. When the anti-freeze molecules are not present, ice filters through their skin at these temperatures and crystallizes (freezes) their blood and tissues. Students will experiment with lowering the freezing point of a substance, thus causing it to remain liquid at a temperature when it is normally solid. Students will compare their findings with facts about Antarctic ice-fish, which have bodily fluids that remain liquid at temperatures below freezing.

  14. Reply to Comment on "Pointy ice-drops: how water freezes into a singular shape", Am. J. Phys. 80, 764-771 (2012)

    E-print Network

    Snoeijer, Jacco

    2012-01-01

    Reply to Comment on "Pointy ice-drops: how water freezes into a singular shape", Am. J. Phys. 80.H. Snoeijer, "Freezing singularities in water drops", Phys. Fluids 24, 053103 (2012). 2 The Gallery of Fluid Dynamics. http://pof.aip.org/gallery of fluid motion 3 http://www.youtube.com/watch?v=9VIRtyKSNVI #12;

  15. The influence of ionizable and non-ionizable compounds in milk upon its freezing point 

    E-print Network

    Pinkerton, Frank

    1955-01-01

    ooatoat bye Chafrnan ot Cossatttoe Eoal of Dopartaont or Stukont visor lngust 195$ TiBLR OP COSTXXTS Page IXTRODUCT I OX . . RXVIXW Oy LITXRLTURX. XXPXRIMXRTdL PROCXDUBX. RXSUI TS, Tho Iaflueaoe of Mastitis oa the pressing Point of Milk, Per... tho routine Babcock fat tost to determine solids not-fat content of milk (Sommer, 1948). 11 The Influeaoe of Mastitis on the Preening Point of Milk, Per Coat Laotoso and Canduotivity Samples wore collected from iafocted quarters of eveniag milk...

  16. An evaluation of freezing as a preservation technique for analyzing dissolved organic C, N and P in surface water samples.

    PubMed

    Fellman, Jason B; D'Amore, David V; Hood, Eran

    2008-03-25

    Techniques for preserving surface water samples are recently in demand because of the increased interest in quantifying dissolved organic matter (DOM) in surface waters and the frequent collection of samples in remote locations. Freezing is a common technique employed by many researchers for preserving surface water samples; however, there has been little evaluation of the effects of freezing on DOM concentrations. Ten streams were sampled in southeast Alaska with a range of dissolved organic carbon (DOC) concentrations (1.5 to 39 mg C L(-1)) to evaluate the influence of freezing (flash and standard freeze) and filter pore size (0.2 and 0.7 mum nominal pore size) on dissolved organic C, N and P concentrations. We report a significant decrease in DOC (p<0.005) and total dissolved P (p<0.005) concentrations when streamwater samples were frozen, whereas concentrations of dissolved organic N did not significantly decrease after freezing (p=0.06). We further show that when surface water samples were frozen, there was a decrease in the specific ultraviolet absorbance (SUVA) of DOC that is particularly evident with high concentrations of DOC. This finding suggests that spectroscopic properties of DOC have the potential to be used as indicators of whether surface water samples can be frozen. Our results lead us to recommend that surface water samples with high DOC concentrations (>5 mg C L(-1)) and/or samples with high SUVA values (>3.5-4 L mg-C(-1) m(-1)) should be analyzed immediately and not frozen. PMID:18164749

  17. Simulation and experiments of low pressure water vapor flows applied to freeze-drying

    Microsoft Academic Search

    Arnab Ganguly

    2010-01-01

    The design of freeze-drying equipment used today is based largely on empirical knowledge. The freeze-dryers used in product manufacturing have changed little since the mid-20th century. A typical pharmaceutical freeze-drying cycle is run as a batch process and is thus, both, time and energy intensive. The equipment design cycle adopted today relies heavily on post-concept tests. This limits the design

  18. Device Maintains Water At The Triple Point

    NASA Technical Reports Server (NTRS)

    West, J. W.; Burkett, C. G.

    1988-01-01

    Inexpensive device maintains water at 0.01 degree C for 10 weeks or longer. New device consists of four basic assemblies; small, commercial chest freezer containing insulated water tank; insulated copper cell holder; "ice switch" for cycling freezer compressor and externally-mounted air pump for circulation. Access hole in freezer lid allows triple point measurements without opening lid. Modified freezer used to calibrate standard platinum resistance thermomenters.

  19. Xylem Embolism in Response to Freeze-Thaw Cycles and Water Stress in Ring-Porous, Diffuse-Porous, and Conifer Species 1

    PubMed Central

    Sperry, John S.; Sullivan, June E. M.

    1992-01-01

    Vulnerability to xylem embolism by freeze-thaw cycles and water stress was quantified in ring-porous (Quercus gambelii Nutt.), diffuse-porous (Populus tremuloides Michx., Betula occidentalis Hook.), and conifer species (Abies lasiocarpa Nutt., Juniperus scopulorum Sarg.). Embolism was measured by its reduction of xylem hydraulic conductivity; it was induced by xylem tension (water-stress response) and by a tension plus a freeze-thaw cycle (freeze response). Conifers showed little (Juniperus) or no (Abies) freeze response even to repeated cycles. In contrast, Quercus embolized more than 90% by freezing at tensions below 0.2 MPa, whereas similar embolism without freezing required tensions above 4.5 MPa. Diffuse-porous trees (Betula, Populus) showed an intermediate freeze response. The magnitude of the freeze response was correlated with conduit volume but occurred at higher tensions than predicted from theory. Large early-wood vessels (2.8 × 10?9 m3) in oak were most vulnerable to embolism by freezing, small vessels in Populus and Betula were intermediate (approximately 7 × 10?11 m3), and tracheids in conifers (about 3 × 10?13 m3) were most resistant. The same trend was found within a stem: embolism by freeze-thawing occurred preferentially in wider conduits. The water-stress response was not correlated with conduit volume; previous work indicates it is a function of interconduit pit membrane structure. Native embolism levels during winter corroborated laboratory results on freezing: Quercus embolized 95% with the first fall freeze, Populus and Betula showed gradual increases to more than 90% embolism by winter's end, and Abies remained below 30%. PMID:16653035

  20. Control of crystal growth in water purification by directional freeze crystallization

    NASA Technical Reports Server (NTRS)

    Conlon, William M. (Inventor)

    1996-01-01

    A Directional Freeze Crystallization system employs an indirect contact heat exchanger to freeze a fraction of liquid to be purified. The unfrozen fraction is drained away and the purified frozen fraction is melted. The heat exchanger must be designed in accordance with a Growth Habit Index to achieve efficient separation of contaminants. If gases are dissolved in the liquid, the system must be pressurized.

  1. Freezing in confined geometries

    NASA Technical Reports Server (NTRS)

    Sokol, P. E.; Ma, W. J.; Herwig, K. W.; Snow, W. M.; Wang, Y.; Koplik, Joel; Banavar, Jayanth R.

    1992-01-01

    Results of detailed structural studies, using elastic neutron scattering, of the freezing of liquid O2 and D2 in porous vycor glass, are presented. The experimental studies have been complemented by computer simulations of the dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls. Results point to a new simple physical interpretation of freezing in confined geometries.

  2. Freezing Fish and Shellfish.

    E-print Network

    Nickelson, Ranzell; Reddell, Annette

    1980-01-01

    contents may impart off-odors and off flavors to the flesh. Digestive enzymes and bacteria found in the intestinal fluids also can begin to digest the fish flesh before the product freezes. The dark flesh of fish is usually less stable in frozen... means of preserving the fresh-caught quality of fish and shellfish. Why Freeze? Freezing preserves foods by lowering their tem peratures to a point not conducive to bacterial growth and natural enzyme action. Many spoilage bacteria are destroyed...

  3. Vacuum Freeze-Drying, a Method Used To Salvage Water-Damaged Archival and Library Materials: A RAMP Study with Guidelines.

    ERIC Educational Resources Information Center

    McCleary, John M.

    This Records and Archives Management Programme (RAMP) study covers the conservation of archival documents and the application of freeze-drying to the salvage of documents damaged by flood. Following an introductory discussion of the hazards of water, the study presents a broad summary of data on freeze-drying, including the behavior of…

  4. Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point

    E-print Network

    Magee, Joseph W.

    Correlation for the Vapor Pressure of Heavy Water From the Triple Point to the Critical Point Allan the vapor pressure of heavy water (D2O) from its triple point to its critical point. This work takes and ordinary water,2­4 a determination of the vapor pressure of D2O at its triple point,5 and the adoption

  5. The effect of freezing on the sulfate-chloride and density-chloride ratios of sea-water 

    E-print Network

    Burkhalter, Albert Charles

    1967-01-01

    for the degree of YAST R OF SCIENCE 'shy f967 Nejor Suhje t: Oceanogrnphy THE EFFECT OF FREEZING ON THE SUIPHATE-CHLORIDE AND DENSITY-CHLORIDE RATIOS OF SEA-WATER A Thesis Albert C. Burkhslter Approved as to styie snd oontent bF: 'Qg, r':, , P: r'. 'W c... present in sea-water are constant, both spatially and temporally and that the determination of any one constituent completely characterires the sea-water. The famous work of Forch, Sorenson and Knudscn (lo02) which rotated the specific gravity...

  6. Antioxidant properties of water and ethanol extracts from hot air-dried and freeze-dried daylily flowers

    Microsoft Academic Search

    Lin-Chun Mao; Xin Pan; Fei Que; Xue-Hua Fang

    2006-01-01

    Daylily (Hemerocallis fulva Linn.) flowers were hot air-dried and freeze-dried after harvest. Water and ethanol extracts were\\u000a prepared from these dried flowers and their antioxidant properties were evaluated using total antioxidant activity, reducing\\u000a capacity, metal chelating activity, and DPPH and superoxide anion radical scavenging activities, comparing with standards.\\u000a Extracts from daylily flowers exhibited strong antioxidant activity. Ethanol was more efficienct

  7. Preliminary Calculation of CaCO3 Precipitation in Freezing Sea Water

    E-print Network

    Meskhidze, Nicholas

    carbonate starts to pre- cipitate from freezing seawater below about -2.2 C. Here, available thermodynamic the buffer capacity of the solution: AT = [OH- ] + [HCO- 3 ] + 2[CO2- 3 ]-[H+ ] (7) This is a common

  8. Real-time Non-contact Millimeter Wave Characterization of Water-Freezing and Ice-Melting Dynamics

    SciTech Connect

    Sundaram, S. K.; Woskov, Paul P.

    2008-11-12

    We applied millimeter wave radiometry for the first time to monitor water-freezing and ice-melting dynamics in real-time non-contact. The measurements were completed at a frequency of 137 GHz. Small amounts (about 2 mL) of freshwater or saltwater were frozen over a Peltier cooler and the freezing and melting sequence was recorded. Saltwater was prepared in the laboratory that contained 3.5% of table salt to simulate the ocean water. The dynamics of freezing-melting was observed by measuring the millimeter wave temperature as well as the changes in the ice or water surface reflectivity and position. This was repeated using large amounts of freshwater and saltwater (800 mL) mimicking glaciers. Millimeter wave surface level fluctuations indicated as the top surface melted, the light ice below floated up indicating lower surface temperature until the ice completely melted. Our results are useful for remote sensing and tracking temperature for potentially large-scale environmental applications, e.g., global warming.

  9. Evaluation of the MilkoScan FT 6000 Milk Analyzer for Determining the Freezing Point of Goat's Milk Under Different Analytical Conditions

    Microsoft Academic Search

    A. Sánchez; D. Sierra; C. Luengo; J. C. Corrales; C. de la Fe; C. T. Morales; A. Contreras; C. Gonzalo

    2007-01-01

    The aim of this research was to evaluate the Milko- Scan FT 6000 (Foss Electric, Hillerød, Denmark) for determining the freezing point (FP) of goat's milk under different analytical conditions. The FP was determined in duplicate in 1,800 milk aliquots obtained from 45 bulk tank milk samples from 10 Murciano-Granadina goat herds, using the MilkoScan method and a reference thermistor

  10. Measurement of water transport during freezing in mammalian liver tissue: Part II--The use of differential scanning calorimetry.

    PubMed

    Devireddy, R V; Bischof, J C

    1998-10-01

    There is currently a need for experimental techniques to assay the biophysical response (water transport or intracellular ice formation, IIF) during freezing in the cells of whole tissue slices. These data are important in understanding and optimizing biomedical applications of freezing, particularly in cryosurgery. This study presents a new technique using a Differential Scanning Calorimeter (DSC) to obtain dynamic and quantitative water transport data in whole tissue slices during freezing. Sprague-Dawley rat liver tissue was chosen as our model system. The DSC was used to monitor quantitatively the heat released by water transported from the unfrozen cell cytoplasm to the partially frozen vascular/extracellular space at 5 degrees C/min. This technique was previously described for use in a single cell suspension system (Devireddy, et al. 1998). A model of water transport was fit to the DSC data using a nonlinear regression curve-fitting technique, which assumes that the rat liver tissue behaves as a two-compartment Krogh cylinder model. The biophysical parameters of water transport for rat liver tissue at 5 degrees C/min were obtained as Lpg = 3.16 x 10(-13) m3/Ns (1.9 microns/min-atm), ELp = 265 kJ/mole (63.4 kcal/mole), respectively. These results compare favorably to water transport parameters in whole liver tissue reported in the first part of this study obtained using a freeze substitution (FS) microscopy technique (Pazhayannur and Bischof, 1997). The DSC technique is shown to be a fast, quantitative, and reproducible technique to measure dynamic water transport in tissue systems. However, there are several limitations to the DSC technique: (a) a priori knowledge that the biophysical response is in fact water transport, (b) the technique cannot be used due to machine limitations at cooling rates greater than 40 degrees C/min, and (c) the tissue geometric dimensions (the Krogh model dimensions) and the osmotically inactive cell volumes Vb, must be determined by low-temperature microscopy techniques. PMID:10412432

  11. Daily reconstruction of water temperature from oxygen isotopic ratios of a modern Tridacna shell using a freezing microtome sampling technique

    NASA Astrophysics Data System (ADS)

    Watanabe, T.; Oba, T.

    1999-09-01

    Daily (1-2 day interval) reconstruction of sea water temperature is calculated via a freezing microtome sampling technique for oxygen isotope analysis and by counting the daily growth lines in a modern Tridacna (Hippopus hippopus, LINNE, 1758) shell collected from Ishigaki Island, Japan. This method enables the first direct comparison between shell oxygen isotopic values and daily meteorological data. The H. hippopus shell calcifies mainly under isotopic equilibrium with surrounding sea water. The high-resolution profile of ?18O of the H. hippopus shell was recorded monthly to seasonal sea surface temperature variations of the local coral reef environment.

  12. Determination of the unfrozen water content of maximally freeze-concentrated carbohydrate solutions.

    PubMed

    Hatley, R H; Mant, A

    1993-08-01

    The heat capacity change at T'g has been studied in freeze-concentrated carbohydrate solutions. The values obtained have been compared with those found for high concentration solutions that do not undergo freezing above Tg. The analysis has indicated that the freezing process influences the degree of stress in the glassy phase. This results in a complex power-time curve when frozen solutions are heated in a differential scanning calorimeter. The endotherm produced by the stress relaxation can cause considerable error in W'g measurement obtained by any method that relies on the integration of the power-time curve. A more reliable method for W'g determination is via the intersection of T'g with a previously prepared Tg/Wg calibration curve. PMID:8373742

  13. Novel Real-Time Diagnosis of the Freezing Process Using an Ultrasonic Transducer

    PubMed Central

    Tseng, Yen-Hsiang; Cheng, Chin-Chi; Cheng, Hong-Ping; Lee, Dasheng

    2015-01-01

    The freezing stage governs several critical parameters of the freeze drying process and the quality of the resulting lyophilized products. This paper presents an integrated ultrasonic transducer (UT) in a stainless steel bottle and its application to real-time diagnostics of the water freezing process. The sensor was directly deposited onto the stainless steel bottle using a sol-gel spray technique. It could operate at temperature range from ?100 to 400 °C and uses an ultrasonic pulse-echo technique. The progression of the freezing process, including water-in, freezing point and final phase change of water, were all clearly observed using ultrasound. The ultrasonic signals could indicate the three stages of the freezing process and evaluate the cooling and freezing periods under various processing conditions. The temperature was also adopted for evaluating the cooling and freezing periods. These periods increased with water volume and decreased with shelf temperature (i.e., speed of freezing). This study demonstrates the effectiveness of the ultrasonic sensor and technology for diagnosing and optimizing the process of water freezing to save energy. PMID:25946629

  14. Eutectic freeze crystallization: Application to process streams and waste water purification

    Microsoft Academic Search

    F. van der Ham; G. J. Witkamp; J. de Graauw; G. M. van Rosmalen

    1998-01-01

    Two case studies are presented using eutectic freeze crystallization (EFC) as an alternative for evaporative crystallization: a 7.8 ton day?1 35 w% aqueous sodium nitrate and a 24 ton day?1 12 w% copper sulfate stream. The proposed crystallizer is a cooled disk column crystallizer (CDCC), using indirect cooling for heat transfer. In single stage operation, the formed ice crystals are

  15. PERFORMANCE OF A REPAIRED WATER TRIPLE POINT CELL IN BRAZIL

    Microsoft Academic Search

    S. G. Petkovic; J. F. N. Santiago; M. S. Monteiro; R. N. Teixeira; P. R. F. Santos

    The water triple point i s the most important fixed p oint of ITS-90 and fundamental for measurements with resistance thermometers. The Thermometry Laboratory of the National Institute for Metrology, Standardisation and Industrial Quality, INMETRO, has been working with water triple point cells since 1981. In order to acquire the necessary technology to b uild a water triple point cell,

  16. Tropical anvil characteristics and water vapor of the tropical tropopause layer: Impact of heterogeneous and homogeneous freezing parameterizations

    NASA Astrophysics Data System (ADS)

    Fan, Jiwen; Comstock, Jennifer M.; Ovchinnikov, Mikhail; McFarlane, Sally A.; McFarquhar, Greg; Allen, Grant

    2010-06-01

    Two isolated deep convective clouds (DCCs) that developed in clean-humid and polluted-dry air masses, observed during the Tropical Pacific Warm Pool International Cloud Experiment (TWP-ICE) and U.K. Aerosol and Chemical Transport in Tropical Convection (ACTIVE) campaigns, respectively, are simulated using a three-dimensional cloud-resolving model with size-resolved aerosol and cloud microphysics. We examine the impacts of different homogeneous and immersion freezing parameterizations on the anvil characteristics and the water vapor content (WVC) in the tropical tropopause layer (TTL) for the two DCCs that developed in contrasting environments. The modeled cloud properties such as liquid/ice water path and precipitation generally agree with the available radar and satellite retrievals and in situ aircraft measurements. We find that anvil microphysical properties such as ice number concentration and ice effective radius (rei) are sensitive to the homogeneous freezing parameterizations (HomFPs) under both the clean-humid and polluted-dry conditions, while upper level convection and WVC in the TTL air are only sensitive to HomFPs under the polluted-dry condition. Specifically, the cloud anvil with the Koop et al. (2000) relative humidity dependent scheme has up to 50% and 70% lower ice number than those with other schemes (temperature dependent) for the clean-humid and polluted-dry cases, respectively. Consequently, the rei is increased by 20-30 ?m in both cases. As a result, extinction coefficient of cloud anvils is reduced by over 30%. Anvil size and evolution are also much affected by HomFPs. Higher immersion-freezing rate (Bigg, 1953) leads to a stronger convective cloud due to larger latent heat release resulted from much higher freezing rates, with larger ice water path but less precipitation in both humid and dry conditions. Consequently, the domain-averaged homogeneous freezing rates are enhanced by over 15%. Also, the higher immersion-freezing rate results in over 1.5 times higher ice number concentrations, much reduced rei in the cloud anvil, and larger anvil size. The moistening effect of deep convection on the TTL clear air is very significant, with increases of a few times relative to the WVC before convection under both humid and dry conditions. Different HomFPs does not make much difference in WVC and upper level convection in the clean-humid case, but in the polluted-dry case, the HomFPs with lower nucleation rates predict about 25% lower WVC relative to the HomFPs with higher nucleation rates. Under both humid and dry conditions, the Bigg (1953) immersion freezing predicts about 25% higher WVC relative to the Vali (1975) parameterization, due to stronger transport and the larger anvil area in the domain.

  17. The effect of freezing on the sulfate-chloride and density-chloride ratios of sea-water

    E-print Network

    Burkhalter, Albert Charles

    1967-01-01

    for the degree of YAST R OF SCIENCE 'shy f967 Nejor Suhje t: Oceanogrnphy THE EFFECT OF FREEZING ON THE SUIPHATE-CHLORIDE AND DENSITY-CHLORIDE RATIOS OF SEA-WATER A Thesis Albert C. Burkhslter Approved as to styie snd oontent bF: 'Qg, r':, , P: r'. 'W c... AC AN~2QZZS LIST OF TABLES I. INTRODUCTION II. LITERATURE REVIEN III. STATEMENT OF PROBLEM IV. EXPER33KfiTAL TECRNIQUES V. D3:SCUSSION VI. CONCLUSION AND SUGGESI'IONS BIBLIOGRAPHY APPEHDIX 16 19 B6 LIST OF TABLES I. KARIlJH CHLORIDE...

  18. Evaluation of the MilkoScan FT 6000 milk analyzer for determining the freezing point of goat's milk under different analytical conditions.

    PubMed

    Sánchez, A; Sierra, D; Luengo, C; Corrales, J C; de la Fe, C; Morales, C T; Contreras, A; Gonzalo, C

    2007-07-01

    The aim of this research was to evaluate the Milko-Scan FT 6000 (Foss Electric, Hillerød, Denmark) for determining the freezing point (FP) of goat's milk under different analytical conditions. The FP was determined in duplicate in 1,800 milk aliquots obtained from 45 bulk tank milk samples from 10 Murciano-Granadina goat herds, using the MilkoScan method and a reference thermistor cryoscopy method (Advanced Instrument Inc., Norwood, MA). Five different preservation strategies--no preservative, preservation with azidiol (0.006 or 0.018 g of sodium azide/100 mL), and preservation with bronopol (0.020 or 0.040 g/100 mL)--were then used to preserve the milk. For each preservation strategy, 8 different amounts of water were added (0, 1, 2, 3, 4, 5, 6, or 7% total volume). The results obtained with each method under these 40 analytical conditions were examined by comparison of means, comparison of the standard deviations of repeatability (s(r) and its relative value s(r)%), and a regression analysis. Under most analytical conditions, the FP was recorded as lower by the MilkoScan method, with a mean difference of 1.5 m degrees C compared with the reference method. Both methods showed similar repeatabilities (the overall s(r)% was 0.22% for the MilkoScan method and 0.20% for the reference method). In comparisons of the 2 methods, the highest regression coefficients were obtained with aliquots containing >3% added water. The best regression coefficients (0.85 to 1.02) were obtained for milk samples preserved with bronopol at 0.020 g/100 mL. These results allow the MilkoScan method to be used with goat's milk for screening purposes. The factors of added water, preservative, analytical method, lactose concentration, and the effect of the bulk tank milk sample within each lactose group contributed significantly to the observed variation in FP. For practical purposes, either of the bronopol concentrations could be used when determining the FP of goat's milk with the methods tested. However, the increase in the concentration of sodium azide in the azidiol formula contributed to an important reduction in the FP recorded. Thus, the type and concentration of preservative should be taken into account when interpreting FP values. PMID:17582097

  19. Experiment and feasibility study on saline water purification by using natural cold resource

    Microsoft Academic Search

    Congshuang Luo

    2011-01-01

    In order to explore an economic, rational, practical method of saline water desalination, this paper mainly uses freeze saline water purification method of experimental study for the exploitation and utilization of natural cold resource. According to the freezing points of water condensate theory, the authors have made cryogenic pilot studies for saline water. we carried out the freezing experiment under

  20. Isotope Exchange and Fractionation Corrections for Extraction of Tritiated Water in Silica Gel by Freeze-Drying Techniques

    SciTech Connect

    Guthrie, E B; Shen, N C; Bandong, B B

    2001-09-24

    A concentration correction curve was established for measuring the activity concentration of airborne tritiated water collected with dried silica gel and extracted by the LLNL Environmental Monitoring Radiological Laboratory freeze-dry technique. A tracer study using standard tritiated water with silica gel showed that the concentration of tritium in the extracted water is lower than that in the adsorbed water by a fraction proportional to the amount of adsorbed water. The observed decrease in tritium concentration in the extracted water can be accounted for by dilution due to isotopic exchange with both non-tritiated water and hydroxyl groups within the silica gel matrix. For the range of 8-35% adsorbed water, which is typical of samples collected in LLNL monitoring stations, the derived exchangeable water in the silica gel material under investigation was (5.12 {+-} 0.08)%. The contribution of the H{sub 2}O/HTO vapor pressure effect using published empirical data in the literature was also considered in calculating the degree of isotopic exchange.

  1. Inhibited ethylene and propylene glycols for corrosion and freeze protection in water-based HVAC systems

    SciTech Connect

    Roo, A.M. de; Lee, B.W. [Dow Chemical Co., Midland, MI (United States)

    1997-12-31

    Industrially inhibited ethylene and propylene glycols are used extensively to provide protection against equipment damage due to corrosion and freezing. This paper will describe the proper use of these glycols, including system preparation, fluid installation, and fluid maintenance. The impact of the use of these glycols on the operation of the system is discussed along with methods for overcoming any declines in heat transfer. From this discussion, it will become clear why automotive antifreeze formulations should not be used in heating, ventilating, and airconditioning (HVAC) systems. Also included are data on the physical properties of aqueous solutions of ethylene and propylene glycol, the concept of burst vs. freeze protection, typical results of corrosion tests, and methods to use to monitor the fluid for each application.

  2. Ripples in Rocks Point to Water

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken by the Mars Exploration Rover Opportunity's panoramic camera shows the rock nicknamed 'Last Chance,' which lies within the outcrop near the rover's landing site at Meridiani Planum, Mars. The image provides evidence for a geologic feature known as ripple cross-stratification. At the base of the rock, layers can be seen dipping downward to the right. The bedding that contains these dipping layers is only one to two centimeters (0.4 to 0.8 inches) thick. In the upper right corner of the rock, layers also dip to the right, but exhibit a weak 'concave-up' geometry. These two features -- the thin, cross-stratified bedding combined with the possible concave geometry -- suggest small ripples with sinuous crest lines. Although wind can produce ripples, they rarely have sinuous crest lines and never form steep, dipping layers at this small scale. The most probable explanation for these ripples is that they were formed in the presence of moving water.

    Crossbedding Evidence for Underwater Origin Interpretations of cross-lamination patterns presented as clues to this martian rock's origin under flowing water are marked on images taken by the panoramic camera and microscopic imager on NASA's Opportunity.

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

    The red arrows (Figure 1) point to features suggesting cross-lamination within the rock called 'Last Chance' taken at a distance of 4.5 meters (15 feet) during Opportunity's 17th sol (February 10, 2004). The inferred sets of fine layers at angles to each other (cross-laminae) are up to 1.4 centimeters (half an inch) thick. For scale, the distance between two vertical cracks in the rock is about 7 centimeters (2.8 inches). The feature indicated by the middle red arrow suggests a pattern called trough cross-lamination, likely produced when flowing water shaped sinuous ripples in underwater sediment and pushed the ripples to migrate in one direction. The direction of the ancient flow would have been either toward or away from the line of sight from this perspective. The lower and upper red arrows point to cross-lamina sets that are consistent with underwater ripples in the sediment having moved in water that was flowing left to right from this perspective.

    The yellow arrows (Figure 2) indicate places in the panoramic camera view that correlate with places in the microscope's view of the same rock.

    [figure removed for brevity, see original site] Figure 3

    The microscopic view (Figure 3) is a mosaic of some of the 152 microscopic imager frames of 'Last Chance' that Opportunity took on sols 39 and 40 (March 3 and 4, 2004).

    [figure removed for brevity, see original site] Figure 4

    Figure 4 shows cross-lamination expressed by lines that trend downward from left to right, traced with black lines in the interpretive overlay. These cross-lamination lines are consistent with dipping planes that would have formed surfaces on the down-current side of migrating ripples. Interpretive blue lines indicate boundaries between possible sets of cross-laminae.

  3. Effect of alkane chain length and counterion on the freezing transition of cationic surfactant adsorbed film at alkane mixture - water interfaces.

    PubMed

    Tokiwa, Yuhei; Sakamoto, Hiroyasu; Takiue, Takanori; Aratono, Makoto; Matsubara, Hiroki

    2015-05-21

    Penetration of alkane molecules into the adsorbed film gives rise to a surface freezing transition of cationic surfactant at the alkane-water interface. To examine the effect of the alkane chain length and counterion on the surface freezing, we employed interfacial tensiometry and ellipsometry to study the interface of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride aqueous solutions against dodecane, tetradecane, hexadecane, and their mixtures. Applying theoretical equations to the experimental results obtained, we found that the alkane molecules that have the same chain length as the surfactant adsorb preferentially into the surface freezing film. Furthermore, we demonstrated that the freezing transition temperature of cationic surfactant adsorbed film was independent of the kind of counterion. PMID:25932500

  4. Flight Instrument for Measurement of Liquid-Water Content in Clouds at Temperatures Above and Below Freezing

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J.

    1951-01-01

    A principle formerly used in an instrument for cloud detection was further investigated to provide a simple and rapid means for measuring the liquid-water content of clouds at temperatures above and below freezing. The instrument consists of a small cylindrical element so operated at high surface temperatures that the impingement of cloud droplets creates a significant drop in the surface temperature. ? The instrument is sensitive to a wide range of liquid-water content and was calibrated at one set of fixed conditions against rotating multicylinder measurements. The limited conditions of the calibration Included an air temperature of 20 F, an air velocity of 175 miles per hour, and a surface temperature in clear air of 475 F. The results obtained from experiments conducted with the instrument indicate that the principle can be used for measurements in clouds at temperatures above and below freezing. Calibrations for ranges of airspeed, air temperature, and air density will be necessary to adapt the Instrument for general flight use.

  5. Wetting and freezing of hexadecane on an aqueous surfactant solution: triple point in a 2-D film.

    PubMed

    Matsubara, H; Ohtomi, E; Aratono, M; Bain, Colin D

    2008-09-18

    Wetting of water by hexadecane has been investigated by ellipsometry as a function of the concentration of the cationic surfactant dodecyltrimethylammonium bromide (DTAB) in the aqueous phase and temperature. Three phases are identified: a 2-D gas of hexadecane molecules and DTAB molecules, a 2-D liquid comprising a mixed monolayer of hexadecane and DTAB, and a 2-D 'solid' phase. Evidence is presented to support the hypothesis that the liquid-solid phase transition is actually a wetting transition in which a surface-frozen layer of pure hexadecane wets the liquid-like mixed monolayer of hexadecane and DTAB. The triple point, at which the three phases coexist, is located at a temperature of 17.3 degrees C and DTAB concentration of 0.75 mmol kg (-1). The slopes of the three phase boundaries are analyzed thermodynamically. PMID:18729394

  6. Clarification of Uncertainty in the Triple Point of Water as a Temperature Fixed Point

    Microsoft Academic Search

    Yoshizo Suyama

    1980-01-01

    The triple point of water in sealed glass cells with commonly recommended specifications possesses incomprehensible characteristics, namely a gradual rise of the triple point temperature by about 0.2 mK during the first few days and, in some cells, a gradual depression after the first ten or so hours. This is a source of uncertainty in the triple point of water

  7. Non-equilibrium freezing of water-ice in sandy basaltic regoliths and implications for fluidized debris flows on Mars

    NASA Technical Reports Server (NTRS)

    Gooding, J. L.

    1987-01-01

    Many geomorphic features on Mars were attributed to Earth-analogous, cold-climate processes involving movement of water or ice lubricated debris. Clearly, knowledge of the behavior of water in regolith materials under Martian conditions is essential to understanding the postulated geomorphic processes. Experiments were performed with sand-sized samples of natural basaltic regoliths in order to further elucidate how water/regolith interactions depend upon grain size and mineralogy. The data reveal important contrasts with data for clay-mineral substrates and suggest that the microphysics of water/mineral interactions might affect Martian geomorphic processes in ways that are not fully appreciated. Sand and silt sized fractions of two soils from the summit of Mauna Kea were used as Mars-analogous regolith materials. Temperatures were measured for water/ice phase transitions as wet slurries of individual soil fractions which were cooled or heated at controlled rates under a carbon dioxide atmosphere. Freezing and melting of ice was studied as a function of water/soil mass ratio, soil particle size, and thermal-cycle rate. Comparison tests were done under the same conditions with U.S. Geological Survey standard rock powders.

  8. Preparation of the Triple Point of Water from a Practical Point of View

    Microsoft Academic Search

    Yoshizo Suyama

    1977-01-01

    A guide to make the triple point cell of water for calibrating precise thermometers with an accuracy of 0.1 mK is studied from a practical point of view. The triple point cell of water can be made by a simple method of filling it with usual distilled water of ˜105 Omega\\\\cdotcm in resistivity under ordinary atmosphere and then degassing the

  9. Protein crowding in solution, frozen and freeze-dried states: small-angle neutron and X-ray scattering study of lysozyme/sorbitol/water systems

    NASA Astrophysics Data System (ADS)

    Krueger, Susan; Khodadadi, Sheila; Clark, Nicholas; McAuley, Arnold; Cristiglio, Viviana; Theyencheri, Narayanan; Curtis, Joseph; Shalaev, Evgenyi

    2015-03-01

    For effective preservation, proteins are often stored as frozen solutions or in glassy states using a freeze-drying process. However, aggregation is often observed after freeze-thaw or reconstitution of freeze-dried powder and the stability of the protein is no longer assured. In this study, small-angle neutron and X-ray scattering (SANS and SAXS) have been used to investigate changes in protein-protein interaction distances of a model protein/cryoprotectant system of lysozyme/sorbitol/water, under representative pharmaceutical processing conditions. The results demonstrate the utility of SAXS and SANS methods to monitor protein crowding at different stages of freezing and drying. The SANS measurements of solution samples showed at least one protein interaction peak corresponding to an interaction distance of ~ 90 Å. In the frozen state, two protein interaction peaks were observed by SANS with corresponding interaction distances at 40 Å as well as 90 Å. On the other hand, both SAXS and SANS data for freeze-dried samples showed three peaks, suggesting interaction distances ranging from ~ 15 Å to 170 Å. Possible interpretations of these interaction peaks will be discussed, as well as the role of sorbitol as a cryoprotectant during the freezing and drying process.

  10. On the use of tert-butanol/water cosolvent systems in production and freeze-drying of poly-?-caprolactone nanoparticles.

    PubMed

    Zelenková, Tereza; Barresi, Antonello A; Fissore, Davide

    2015-01-01

    This work deals with the use of a water/tert-butyl alcohol (TBA) system in the manufacturing process of poly-?-caprolactone (PCL) nanoparticles, namely in the synthesis stage, using the solvent displacement method in a confined impinging jet mixer (CIJM), and in the following freeze-drying stage. The experimental investigation evidenced that the nanoparticles size is significantly reduced with respect to the case where acetone is the solvent. Besides, the solvent evaporation step is not required before freeze-drying as TBA is fully compatible with the freeze-drying process. The effect of initial polymer concentration, flow rate, water to TBA flow rate ratio, and quench volumetric ratio on the mean nanoparticles size was investigated, and a simple equation was proposed to relate the mean nanoparticles size to these operating parameters. Then, freeze-drying of the nanoparticles suspensions was studied. Lyoprotectants (sucrose and mannitol) and steric stabilizers (Cremophor EL and Poloxamer 388) have to be used to avoid nanoparticles aggregation, thus preserving particle size distribution and mean nanoparticles size. Their effect, as well as that of the heating shelf temperature, has been investigated by means of statistical techniques, with the goal to identify which of these factors, or combination of factors, plays the key role in the nanoparticles size preservation at the end of the freeze-drying process. PMID:25421731

  11. 40 CFR 142.57 - Bottled water, point-of-use, and point-of-entry devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Bottled water, point-of-use, and point-of-entry...the Administrator § 142.57 Bottled water, point-of-use, and point-of-entry...require a public water system to use bottled water, point-of-use...

  12. 40 CFR 142.57 - Bottled water, point-of-use, and point-of-entry devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Bottled water, point-of-use, and point-of-entry...the Administrator § 142.57 Bottled water, point-of-use, and point-of-entry...require a public water system to use bottled water, point-of-use...

  13. Non-Toxic, Low-Freezing, Drop-In Replacement Heat Transfer Fluids

    NASA Technical Reports Server (NTRS)

    Cutbirth, J. Michael

    2012-01-01

    A non-toxic, non-flammable, low-freezing heat transfer fluid is being developed for drop-in replacement within current and future heat transfer loops currently using water or alcohol-based coolants. Numerous water-soluble compounds were down-selected and screened for toxicological, physical, chemical, compatibility, thermodynamic, and heat transfer properties. Two fluids were developed, one with a freezing point near 0 C, and one with a suppressed freezing point. Both fluids contain an additive package to improve material compatibility and microbial resistance. The optimized sub-zero solution had a freezing point of 30 C, and a freezing volume expansion of 10-percent of water. The toxicity of the solutions was experimentally determined as LD(50) greater than 5g/kg. The solutions were found to produce minimal corrosion with materials identified by NASA as potentially existing in secondary cooling loops. Thermal/hydrodynamic performance exceeded that of glycol-based fluids with comparable freezing points for temperatures Tf greater than 20 C. The additive package was demonstrated as a buffering agent to compensate for CO2 absorption, and to prevent microbial growth. The optimized solutions were determined to have physically/chemically stable shelf lives for freeze/thaw cycles and longterm test loop tests.

  14. Droplet Freezing by Surface Nucleation

    Microsoft Academic Search

    Narayan R. Gokhale; James Goold Jr.

    1968-01-01

    Droplet freezing by surface nucleation has been observed during the course of studies of ice nucleation in our laboratories. A constant rate of cooling apparatus and a specially constructed cold chamber were used for this study. Silver iodide particles sprinkled on supercooled, millimeter-size water drops are effective in freezing the drops at 5C. Particles of naturally occurring silicates were found

  15. Elimination of bicarbonate interference in the binding of U(VI) in mill-waters to freeze-dried Chlorella vulgaris

    Microsoft Academic Search

    Benjamin Greene; Michael T. Henzl; J. Michael Hosea; Dennis W. Darnall

    1986-01-01

    Freeze-dried preparations of Chlorella vulgaris will accumulate U(Vl) from alkaline, bicarbonate-containing waters collected from uranium mill process streams, provided that the pH is pre-adjusted to between 4.0 and 6.0. Bicarbonate ion complexes the uranyl ion in these waters and seriously interferes with the binding of U(Vl) to the algal cells at pH values above 6.0. No binding of U(Vl) to

  16. The effects of freezing and thawing on the aqueous availability of creosote contamination in soil

    SciTech Connect

    Bevel, A.; Hrudey, S.; Dudas, M.; Sego, D. [Univ. of Alberta, Edmonton, Alberta (Canada)

    1996-11-01

    A variety of methods have been tested in attempts to remediate contaminated sites. Fine-grained soils are extremely problematic to remediate, due to the high adsorption capacity of the fine soil particles and the trapping effect of soil particle micropores. It is well documented that freezing of soil causes particle restructuring and reorganization, with different pore structures found after freezing. Some factors affecting restructuring include soil moisture content, freezing rate, freezing end-point temperature, and number of freezing cycles. This poster presents an experiment that determines if freezing creosote contaminated soil improves accessibility of the creosote, by measuring aqueous phase contaminant dissolution. This method was selected since water is the most common solvent in naturally occurring systems, and water represents a worst-case scenario since many contaminants have low aqueous solubilities. Freezing is carried out under controlled laboratory conditions. Variables examined include moisture content, freezing rate, and soil contamination level. If contaminant availability is increased through soil freezing, remediation becomes an easier task in fine grained soils.

  17. Improvement of Freezing Quality of Food by Pre-dehydration with Microwave-Vacuum Drying

    NASA Astrophysics Data System (ADS)

    Hamidi, Nurkholis; Tsuruta, Takaharu

    Partial dehydration by microwave vacuum drying has been applied to tuna, oyster and mackerel prior to freezing in order to reduce quality damages due to freezing and thawing. Samples were dehydrated at pressure of 4kPa and temperature lower than 25°C. Two cooling conditions were tested in the experiment by using the freezing chamber of temperatures -20°C and -80°C. The experimental results showed that decreasing the water content in tuna could lower the freezing point temperature and made the freezing time shorter. It was also found that removing some water was effective to reduce the size of ice crystal and the drip loss in mackerel. After thawing, the pre-dehydrated mackerel showed better microstructure than that frozen without pre-treatment. Furthermore, the sensory tests have been done by a group of panelist for the evaluation on aroma, flavor, and general acceptability of mackerels.

  18. SOLERAS - Solar-Powered Water Desalination Project at Yanbu: Indirect freeze desalination system performance

    Microsoft Academic Search

    J. C. Zimmerman; N. Al-Abbadi

    1987-01-01

    The desalination subsystem of the solar-powered desalination pilot project located at Yanbu, Saudi Arabia, was operated successfully for two years. Water production rates of 180 m³\\/day can be obtained for a period of 24 hours. In addition, once the proper procedures are followed, water production can continue for long periods of time at rates of 135 m³\\/day. Electrical energy costs

  19. Isotopic composition of water used for triple point of water cells

    Microsoft Academic Search

    J. V. Nicholas; T. D. Dransfield; D. R. White

    1996-01-01

    Measurements of the isotopic composition of water used in the production of triple point of water cells show that state-of-the-art triple point realizations must consider corrections and uncertainties due to variations in the isotopic composition of water. Triple point cell production processes yield cells with triple point temperatures 60 µK below that implied by the definition, with a similar sized

  20. Bjorken expansion with gradual freeze out

    E-print Network

    V. K. Magas; L. P. Csernai; E. Molnar

    2007-02-27

    The freeze out of the expanding systems, created in relativistic heavy ion collisions, will be discussed. We combine kinetic freeze out equations with Bjorken type system expansion into a unified model. Such a model is a more physical generalization of the earlier simplified non-expanding freeze out models. We shall see that the basic freeze out features, pointed out in the earlier works, are not smeared out by the expansion.

  1. Studies on the Behavior of Water Triple-Point Cells

    Microsoft Academic Search

    Shu-Fei Tsai

    2003-01-01

    Several triple point of water (TPW) cells from four different manufacturers were investigated in the same TPW maintenance bath with three standard platinum resistance thermometers. Temperature differences between the water triple point among cells were analyzed and found to be within 0.319 mK and repeatability to 0.015 mK over four to five months. The variations of temperature with height in

  2. Ceramic water filter for point-of-use water treatment in Limpopo province, South Africa

    Microsoft Academic Search

    Tshepo Alex Malapane; Caroline Hackett; Vhonani Netshandama; James Smith

    2012-01-01

    This paper describes the design of a ceramic water filter factory in Mashamba Village, Limpopo province, South Africa. In rural settings, water contamination occurs mainly at the point-of-use (POU), or household level and water purification in Limpopo province is still a huge challenge. Locally manufactured ceramic water filters have been proven to significantly improve the microbiological quality of water when

  3. When water does not boil at the boiling point.

    PubMed

    Chang, Hasok

    2007-03-01

    Every schoolchild learns that, under standard pressure, pure water always boils at 100 degrees C. Except that it does not. By the late 18th century, pioneering scientists had already discovered great variations in the boiling temperature of water under fixed pressure. So, why have most of us been taught that the boiling point of water is constant? And, if it is not constant, how can it be used as a 'fixed point' for the calibration of thermometers? History of science has the answers. PMID:17336380

  4. Freeze stabilization and cryopreparation technique for visualizing the water distribution in woody tissues by X-ray imaging and cryo-scanning electron microscopy.

    PubMed

    Utsumi, Yasuhiro; Sano, Yuzou

    2014-01-01

    The protocol of freeze stabilization and cryopreparation techniques to examine the distribution of water in living tree stems by X-ray imaging and cryo-scanning electron microscopy have been developed and described. The brief procedures are as follows. Firstly, a portion of transpiring stem is frozen in the standing state with liquid nitrogen to stabilize the water that is present in the conducting tissue. After filling with liquid nitrogen, discs are then collected from the frozen portion of the stem and stored in liquid nitrogen. In a low-temperature room, the samples for X-ray imaging are sectioned with a fine handsaw, and trimmed sample blokes for cryo-scanning electron microscopy are cleanly planed using a sliding microtome. Finally, the frozen sections are irradiated in a soft X-ray apparatus, and the small blocks are examined in cryo-scanning electron microscope after freeze-etching and metal coating. PMID:24357385

  5. The Effect of Whey Protein Isolate-Dextran Conjugates on the Freeze-Thaw Stability of Oil-in-Water Emulsions

    Microsoft Academic Search

    Duoxia Xu; Fang Yuan; Xiaoya Wang; Xiaoting Li; Zhanqun Hou; Yanxiang Gao

    2010-01-01

    This study examines the impact of Maillard-type conjugates formed between whey protein isolate (WPI) and the nonionic polysaccharide dextran by dry heating at 80°C for 2 hours (conjugate 1) and at 60°C for 5 days (conjugate 2) on the freeze-thaw stability of oil-in-water emulsions. Emulsions stabilized with WPI, WPI-dextran mixture, conjugates 1 and 2, were prepared using microfluidizer, respectively, and

  6. Experimental and analytical investigation of a freezing point depressant fluid ice protection system. M.S. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Albright, A. E.

    1984-01-01

    A glycol-exuding porous leading edge ice protection system was tested in the NASA Icing Research Tunnel. Stainless steel mesh, laser drilled titanium, and composite panels were tested on two general aviation wing sections. Two different glycol-water solutions were evaluated. Minimum glycol flow rates required for anti-icing were obtained as a function of angle of attack, liquid water content, volume median drop diameter, temperature, and velocity. Ice accretions formed after five minutes of icing were shed in three minutes or less using a glycol fluid flow equal to the anti-ice flow rate. Two methods of predicting anti-ice flow rates are presented and compared with a large experimental data base of anti-ice flow rates over a wide range of icing conditions. The first method presented in the ADS-4 document typically predicts flow rates lower than the experimental flow rates. The second method, originally published in 1983, typically predicts flow rates up to 25 percent higher than the experimental flow rates. This method proved to be more consistent between wing-panel configurations. Significant correlation coefficients between the predicted flow rates and the experimental flow rates ranged from .867 to .947.

  7. Non-freezing water content of mono- and divalent cation salts of polyelectrolyte-water systems studied by DSC

    Microsoft Academic Search

    Tatsuko Hatakeyama; Hyoe Hatakeyama; Kunio Nakamura

    1995-01-01

    The number of bound water molecules restricted by mono-, di-, and trivalent cations in polyelectrolytes, such as polystyrene sulphonate, carboxymethylcellulose and alginic acid, was calculated using DSC. The number of bound water molecules decreases with increasing ionic radius in the series of mono- and divalent cations when polyelectrolytes form the liquid crystalline state. However, when polyelectrolytes form rigid junction zones

  8. Freeze Protection for Gasholders ESGI64 Freeze Protection in Gasholders

    E-print Network

    Purvis, Richard

    and National Grid wishes to inves- tigate whether circulation of the tank water without external heating could of "tank water" at the base which is below ground. At present freeze- protection is achieved by external capacity and National Grid wishes to investi- gate whether circulation of the tank water without external

  9. New methods of subcooled water recognition in dew point hygrometers

    NASA Astrophysics Data System (ADS)

    Weremczuk, Jerzy; Jachowicz, Ryszard

    2001-08-01

    Two new methods of sub-cooled water recognition in dew point hygrometers are presented in this paper. The first one- impedance method use a new semiconductor mirror in which the dew point detector, the thermometer and the heaters were integrated all together. The second one an optical method based on a multi-section optical detector is discussed in the report. Experimental results of both methods are shown. New types of dew pont hydrometers of ability to recognized sub-cooled water were proposed.

  10. Isotopic Correction of Water-Triple-Point Cells at NMIJ

    Microsoft Academic Search

    Jun Tamba; Muneo Sakai; Isao Kishimoto; Masaru Arai

    2008-01-01

    The twenty-one participating laboratories in the international key comparison of water-triple-point cells (CCT-K7) can be\\u000a classified into three groups: two laboratories that corrected the effect of the isotopic composition of water, four laboratories\\u000a that had information on the isotopic composition but did not correct the effect, and the remaining laboratories that had no\\u000a information. There were significant differences in the

  11. Isotopic Composition of Water Used in Triple-Point Cells

    Microsoft Academic Search

    K. S. Gam; K. H. Kang; Y.-G. Kim; I. Yang

    2008-01-01

    Isotopic analysis of the water used in KRISS triple point of water (TPW) cells was performed by three separate laboratories. The deltaD and delta 18O isotopic composition of six ampoules, made from two TPW cells, were analyzed by isotope ratio mass spectrometers. The analysis data showed that deltaD and delta 18O were - 62.170\\/00 and - 9.410\\/00 for the KRISS-2002-Jan

  12. Isotopic Composition of Water Used in Triple-Point Cells

    Microsoft Academic Search

    K. S. Gam; K. H. Kang; Y.-G. Kim; I. Yang

    2008-01-01

    Isotopic analysis of the water used in KRISS triple point of water (TPW) cells was performed by three separate laboratories.\\u000a The ?D and ?\\u000a 18O isotopic composition of six ampoules, made from two TPW cells, were analyzed by isotope ratio mass spectrometers. The analysis\\u000a data showed that ?D and ?\\u000a 18O were ? 62.17‰ and ? 9.41‰ for the KRISS-2002-Jan cell, and

  13. Novel ultra-rapid freezing particle engineering process for enhancement of dissolution rates of poorly water-soluble drugs.

    PubMed

    Overhoff, Kirk A; Engstrom, Josh D; Chen, Bo; Scherzer, Brian D; Milner, Thomas E; Johnston, Keith P; Williams, Robert O

    2007-01-01

    An ultra-rapid freezing (URF) technology has been developed to produce high surface area powders composed of solid solutions of an active pharmaceutical ingredient (API) and a polymer stabilizer. A solution of API and polymer excipient(s) is spread on a cold solid surface to form a thin film that freezes in 50 ms to 1s. This study provides an understanding of how the solvent's physical properties and the thin film geometry influence the freezing rate and consequently the final physico-chemical properties of URF-processed powders. Theoretical calculations of heat transfer rates are shown to be in agreement with infrared images with 10ms resolution. Danazol (DAN)/polyvinylpyrrolidone (PVP) powders, produced from both acetonitrile (ACN) and tert-butanol (T-BUT) as the solvent, were amorphous with high surface areas (approximately 28-30 m2/g) and enhanced dissolution rates. However, differences in surface morphology were observed and attributed to the cooling rate (film thickness) as predicted by the model. Relative to spray-freezing processes that use liquid nitrogen, URF also offers fast heat transfer rates as a result of the intimate contact between the solution and cold solid surface, but without the complexity of cryogen evaporation (Leidenfrost effect). The ability to produce amorphous high surface area powders with submicron primary particles with a simple ultra-rapid freezing process is of practical interest in particle engineering to increase dissolution rates, and ultimately bioavailability. PMID:16987642

  14. Entropic Aspects of Supercooled Droplet Freezing ALEXANDER KOSTINSKI AND WILL CANTRELL

    E-print Network

    Kostinski, Alex

    pressures1 and then using the Clausius­Clapeyron equation as well as the triple-point identity, in final form 27 December 2007) ABSTRACT The freezing of supercooled water droplets in the atmosphere, with an emphasis on the entropic aspects of the problem, is examined. Supercooled water is a metastable state and

  15. Interlaboratory comparison of realizations of the triple point of water

    Microsoft Academic Search

    E. Renaot; M. Elgourdou; G. Bonnier

    2000-01-01

    An interlaboratory comparison of the different realizations of the triple point of water (TPW) in Europe has been organized by EUROMET (Project No. 278). This project was based on the circulation of one TPW cell and an isothermal enclosure. The national metrology institutes of thirteen countries and the Bureau International des Poids et Mesures were involved in the work. Twenty-seven

  16. Freeze Technology for Nuclear Applications - 13590

    SciTech Connect

    Rostmark, Susanne C.; Knutsson, Sven [Lulea University of Technology (Sweden)] [Lulea University of Technology (Sweden); Lindberg, Maria [Studsvik Nuclear AB, 611 82 Nykoeping (Sweden)] [Studsvik Nuclear AB, 611 82 Nykoeping (Sweden)

    2013-07-01

    Freezing of soil materials is a complicated process of a number of physical processes: - freezing of pore water in a thermal gradient, - cryogenic suction causing water migration and - ice formation expanding pores inducing frost heave. Structural changes due to increase of effective stress during freezing also take place. The over consolidation gives a powerful dewatering/drying effect and the freeze process causes separation of contaminates. Artificial ground freezing (AGF is a well established technique first practiced in south Wales, as early as 1862. AGF is mostly used to stabilize tunnels and excavations. During the last ten years underwater applications of freeze technologies based on the AGF have been explored in Sweden. The technology can, and has been, used in many different steps in a remediation action. Freeze Sampling where undisturbed samples are removed in both soft and hard sediment/sludge, Freeze Dredging; retrieval of sediment with good precision and minimal redistribution, and Freeze Drying; volume reduction of contaminated sludge/sediment. The application of these technologies in a nuclear or radioactive environment provides several advantages. Sampling by freezing gives for example an advantage of an undisturbed sample taken at a specified depth, salvaging objects by freezing or removal of sludges is other applications of this, for the nuclear industry, novel technology. (authors)

  17. Freezing Cleans Water

    NSDL National Science Digital Library

    This site helps to describe the technology of Snowfluent, a product which atomizes wastewater and sprays it into the air at cold temperatures. The article addresses the potential uses for this technology and also discusses the studies behind the development of Snowfluent.

  18. Metabolic engineering of oilseed crops to produce high levels of novel acetyl glyceride oils with reduced viscosity, freezing point and calorific value.

    PubMed

    Liu, Jinjie; Rice, Adam; McGlew, Kathleen; Shaw, Vincent; Park, Hyunwoo; Clemente, Tom; Pollard, Mike; Ohlrogge, John; Durrett, Timothy P

    2015-08-01

    Seed oils have proved recalcitrant to modification for the production of industrially useful lipids. Here, we demonstrate the successful metabolic engineering and subsequent field production of an oilseed crop with the highest accumulation of unusual oil achieved so far in transgenic plants. Previously, expression of the Euonymus alatus diacylglycerol acetyltransferase (EaDAcT) gene in wild-type Arabidopsis seeds resulted in the accumulation of 45 mol% of unusual 3-acetyl-1,2-diacyl-sn-glycerols (acetyl-TAGs) in the seed oil (Durrett et al., 2010 PNAS 107:9464). Expression of EaDAcT in dgat1 mutants compromised in their ability to synthesize regular triacylglycerols increased acetyl-TAGs to 65 mol%. Camelina and soybean transformed with the EaDAcT gene accumulate acetyl-triacylglycerols (acetyl-TAGs) at up to 70 mol% of seed oil. A similar strategy of coexpression of EaDAcT together with RNAi suppression of DGAT1 increased acetyl-TAG levels to up to 85 mol% in field-grown transgenic Camelina. Additionally, total moles of triacylglycerol (TAG) per seed increased 20%. Analysis of the acetyl-TAG fraction revealed a twofold reduction in very long chain fatty acids (VLCFA), consistent with their displacement from the sn-3 position by acetate. Seed germination remained high, and seedlings were able to metabolize the stored acetyl-TAGs as rapidly as regular triacylglycerols. Viscosity, freezing point and caloric content of the Camelina acetyl-TAG oils were reduced, enabling use of this oil in several nonfood and food applications. PMID:25756355

  19. Commercial Application of Freeze Crystallization

    E-print Network

    Gorgol, R. G.

    begun to realize water is a very valuable resource. Even municipalities must husband thcir water. The day is coming very soon when all industrywill produce clean water as a cash product and water use will be carefully managed. Everywhere you look... becn since the world bcgan. The most noticeable frozen substance is, of course, water. Snow, ice cubcs, frozen lakes and streams, even iccbcrgs are all evidences of the freezing process at work. This process is also used to form crystalline...

  20. Point based hydrodynamics applied to shallow water equations

    SciTech Connect

    Eltgroth, P.

    1994-05-01

    Smoothed Particle Hydrodynamics (SPH) has proven useful for many problems of scientific interest. This report is concerned with a generalization to the SPH method which may be of value for problems such as climate modeling. The main objective of the work is to carry out the new formulation, called Point Interactive Physics and to compare results for PIP and standard finite difference techniques on a simple test problem. The basic SPH approach describes a system using a set of points. These points are not associated with a grid or mesh, as in most approaches. The individual points are each assigned a mass and move with the material velocity. Thus the original SPH method is Lagrangian. Properties of the system are expressed as sums over the sample points using a weighting function called a kernel function. For most problems, tile weighting function extends over a relatively short range, called the smoothing length. The Point Interacting Physics (PIP) approach also samples information at a set of points, and then uses kernel functions to infer physical properties everywhere. The points are not assigned fixed values of miss and they are allowed to undergo arbitrary physically reasonable motion. In this report, results will be presented for fixed points arranged irregularly over a spherical surface. Thus, this version of PIP will be applied in an Eulerian fashion. The basic reason for the Eulerian treatment is enhanced efficiency arising from the fixed geometric relationships among the points. After a brief description of the SPH and PIP methods, the PIP formulation will be compared to a normal finite difference approach for a simple shallow water advection test problem. It appears that accurate simulations can be accomplished, but that computational speed is comparable to that observed for other techniques.

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

    PubMed

    Bertrand, C E; Anisimov, M A

    2011-12-01

    On the basis of the principle of critical-point universality, we examine the peculiar thermodynamics of the liquid-liquid critical point in supercooled water. We show that the liquid-liquid criticality in water represents a special kind of critical behavior in fluids, intermediate between two limiting cases: the lattice gas, commonly used to model liquid-vapor transitions, and the lattice liquid, a weakly compressible liquid with an entropy-driven phase separation. While the ordering field in the lattice gas is associated with the chemical potential and the order parameter with the density, in the lattice liquid the ordering field is the temperature and the order parameter is the entropy. The behavior of supercooled water is much closer to lattice-liquid behavior than to lattice-gas behavior. Using new experimental data recently obtained by Mishima [J. Chem. Phys. 2010, 133, 144503], we have revised the parametric scaled equation of state, previously suggested by Fuentevilla and Anisimov [Phys. Rev. Lett. 2006, 97, 195702], and obtain a consistent description of the thermodynamic anomalies of supercooled water by adjusting linear backgrounds, one critical amplitude, and the critical pressure. We also show how the lattice-liquid description affects the finite-size scaling description of supercooled water in confined media. PMID:21661753

  2. Particle-size dependence of immersion freezing: Investigation of INUIT test aerosol particles with freely suspended water drops.

    NASA Astrophysics Data System (ADS)

    Diehl, Karoline; Debertshäuser, Michael; Eppers, Oliver; Jantsch, Evelyn; Mitra, Subir K.

    2014-05-01

    One goal of the research group INUIT (Ice Nuclei research UnIT) is to investigate the efficiencies of several test ice nuclei under comparable conditions but with different experimental techniques. In the present studies, two methods are used: the Mainz vertical wind tunnel and an acoustic levitator placed inside a cold chamber. In both cases drops are freely levitated, either at their terminal velocity in the wind tunnel updraft or around the nodes of a standing ultrasonic wave in the acoustic levitator. Thus, heat transfer conditions are well approximated, and wall contact effects on freezing as well as electrical charges of the drops are avoided. Drop radii are 370 ?m and 1 mm, respectively. In the wind tunnel, drops are investigated at constant temperatures within a certain time period and the onset of freezing is observed directly. In the acoustic levitator, the drop temperature decreases during the experiments and is measured by an in-situ calibrated Infrared thermometer. The onset of freezing is indicated by a rapid rise of the drop surface temperature because of the release of latent heat. Investigated test ice nuclei are Snomax® as a proxy of biological particles and illite NX as well as K-feldspar as represents of mineral dust. The particle concentrations are 1 × 10-12 to 3 × 10-6 g Snomax® per drop and 5 × 10-9 to 5 × 10-5 g mineral dust per drop. Freezing temperatures are between -2 and -18° C in case of Snomax® and between -14 and -26° C in case of mineral dust. The lower the particle masses per drop the lower are the freezing temperatures. For similar particle concentrations in the drops, the median freezing temperatures determined by the two techniques agree well within the measurement errors. With the knowledge of the specific particle surface area of the mineral dusts, the results are interpreted also in terms of particle surface area per drop. Results from the wind tunnel experiments which are performed at constant temperatures indicate that the freezing times are shorter the lower the temperatures are. For evaluation and comparisons of the data, two models of heterogeneous freezing are applied, the stochastic and the time-independent singular description. The nucleation rate coefficients J(T) as well as the surface densities of active sites ns(T) or the numbers of active sites nm(T) are determined from the experimental data. It is shown that both models are suited to describe the present heterogeneous freezing results for the range of investigated particle masses or surface areas per drop. The comparison of the results from the two experimental techniques evaluated with the time-independent singular model indicates an excellent agreement within the measurement errors.

  3. Preservation of flavor in freeze dried green beans

    NASA Technical Reports Server (NTRS)

    Huber, C. S.; Heidelbaugh, N. D.; Davis, D.

    1973-01-01

    Before freeze drying, green beans are heated to point at which their cell structure is altered. Beans freeze dried with altered cell structure have improved rehydration properties and retain color, flavor, and texture.

  4. Radiation Thermometry Toward the Triple Point of Water?

    Microsoft Academic Search

    Jürgen Hartmann; Lutz Werner

    2008-01-01

    The article describes and evaluates the possibility of using a high-temperature blackbody of accurately known thermodynamic\\u000a temperature as a reference source for the determination of lower thermodynamic temperatures by spectral radiation thermometry.\\u000a By applying various intermediate steps, this approach will allow spectral radiation thermometry to be used for the determination\\u000a of the thermodynamic temperature of the triple point of water

  5. Stability against freezing of aqueous solutions on early Mars.

    PubMed

    Fairén, Alberto G; Davila, Alfonso F; Gago-Duport, Luis; Amils, Ricardo; McKay, Christopher P

    2009-05-21

    Many features of the Martian landscape are thought to have been formed by liquid water flow and water-related mineralogies on the surface of Mars are widespread and abundant. Several lines of evidence, however, suggest that Mars has been cold with mean global temperatures well below the freezing point of pure water. Martian climate modellers considering a combination of greenhouse gases at a range of partial pressures find it challenging to simulate global mean Martian surface temperatures above 273 K, and local thermal sources cannot account for the widespread distribution of hydrated and evaporitic minerals throughout the Martian landscape. Solutes could depress the melting point of water in a frozen Martian environment, providing a plausible solution to the early Mars climate paradox. Here we model the freezing and evaporation processes of Martian fluids with a composition resulting from the weathering of basalts, as reflected in the chemical compositions at Mars landing sites. Our results show that a significant fraction of weathering fluids loaded with Si, Fe, S, Mg, Ca, Cl, Na, K and Al remain in the liquid state at temperatures well below 273 K. We tested our model by analysing the mineralogies yielded by the evolution of the solutions: the resulting mineral assemblages are analogous to those actually identified on the Martian surface. This stability against freezing of Martian fluids can explain saline liquid water activity on the surface of Mars at mean global temperatures well below 273 K. PMID:19458717

  6. Modification of physical properties of freeze-dried rice

    NASA Technical Reports Server (NTRS)

    Huber, C. S.

    1971-01-01

    Freeze cycling process consists of alternately freezing and thawing precooked rice for two cycles, rice is then frozen and freeze-dehydrated in vacuum sufficient to remove water from rice by sublimitation. Process modifies rice grain structure and porosity, enabling complete rehydration in one minute in hot water.

  7. Benchmarking numerical freeze/thaw models

    NASA Astrophysics Data System (ADS)

    Rühaak, Wolfram; Anbergen, Hauke; Molson, John; Grenier, Christophe; Sass, Ingo

    2015-04-01

    The modeling of freezing and thawing of water in porous media is of increasing interest, and for which very different application areas exist. For instance, the modeling of permafrost regression with respect to climate change issues is one area, while others include geotechnical applications in tunneling and for borehole heat exchangers which operate at temperatures below the freezing point. The modeling of these processes requires the solution of a coupled non-linear system of partial differential equations for flow and heat transport in space and time. Different code implementations have been developed in the past. Analytical solutions exist only for simple cases. Consequently, an interest has arisen in benchmarking different codes with analytical solutions, experiments and purely numerical results, similar to the long-standing DECOVALEX and the more recent "Geothermal Code Comparison" activities. The name for this freezing/ thawing benchmark consortium is INTERFROST. In addition to the well-known so-called Lunardini solution for a 1D case (case T1), two different 2D problems will be presented, one which represents melting of a frozen inclusion (case TH2) and another which represents the growth or thaw of permafrost around a talik (case TH3). These talik regions are important for controlling groundwater movement within a mainly frozen ground. First results of the different benchmark results will be shown and discussed.

  8. Quantum Zero Point Effects in Water and Ice

    NASA Astrophysics Data System (ADS)

    Pamuk, Betül; Fernández-Serra, Marivi

    2013-03-01

    Nuclear zero point effects have recently been shown to have an interesting quantum anomaly in ice. In particular, In hexagonal ice Ih, the lattice volume increases when H is replaced by D. This anomalous isotope shift of the lattice parameter increases with temperature, contrary to normal expectations. Free energy calculations within the quasiharmonic approximation, with ab initio density functional theory, explain the origin of his anomaly. In this study, we extend our study to show that the anomalous isotope effect persists in amorphous ices, inherent structures of liquid water. This indicates that the anomalous isotope effect on the density of liquid water might be intrinsically related to the one observed in ice, even if their structures are radically different. In addition, we show that clathrate hydrides, also have this anomaly. We make a detailed analysis of the origin of the anomaly and study how the Hbond interaction and the vdW bond in liquid water are modified by these nuclear zero point effects. Nuclear zero point effects have recently been shown to have an interesting quantum anomaly in ice. In particular, In hexagonal ice Ih, the lattice volume increases when H is replaced by D. This anomalous isotope shift of the lattice parameter increases with temperature, contrary to normal expectations. Free energy calculations within the quasiharmonic approximation, with ab initio density functional theory, explain the origin of his anomaly. In this study, we extend our study to show that the anomalous isotope effect persists in amorphous ices, inherent structures of liquid water. This indicates that the anomalous isotope effect on the density of liquid water might be intrinsically related to the one observed in ice, even if their structures are radically different. In addition, we show that clathrate hydrides, also have this anomaly. We make a detailed analysis of the origin of the anomaly and study how the Hbond interaction and the vdW bond in liquid water are modified by these nuclear zero point effects. This work is supported by DOE Grant No. DE-SC0003871

  9. POINT-OF-CONTACT/EXPERTISE LIST (WATER SUPPLY AND WATER RESOURCES DIVISION, NRMRL)

    EPA Science Inventory

    NRMRL's Water Supply and Water Resources Division's (WSWRD's)Expertise/Point-of-Contact page lists research areas in the Division along with the names and telephone numbers for responsible individuals and their expertise. WSWRD conducts research to help prepare the primary and s...

  10. Effect of water content on thermal behavior of freeze-dried soy whey and their isolated proteins.

    PubMed

    Sobral, Pablo A; Palazolo, Gonzalo G; Wagner, Jorge R

    2011-04-27

    Thermal behavior of lyophilized soy whey (LSW) and whey soy proteins (WSP) at different water contents (WC) was studied by DSC. In anhydrous condition, Kunitz trypsin inhibitor (KTI) and lectin (L) were more heat stable for WSP with respect to LSW sample. The increase of WC destabilized both proteins but differently depending on the sample analyzed. Thermal stability inversion of KTI and L was observed for WSP and LSW at 50.0% and 17.0% WC, respectively, which correspond to the same water-protein content mass ratio (W/P ? 1.9). At W/P < 1.9, KTI was more heat stable than L. Before the inversion point, WC strongly modified the peak temperatures (T(p)) of KTI and L for WSP, whereas this behavior was not observed for LSW. The high sugar content was responsible for the thermal behavior of KTI and L in LSW under anhydrous condition and low WC. These results have important implications for the soy whey processing and inactivation of antinutritional factors. PMID:21413812

  11. Development and design of sludge freezing beds

    SciTech Connect

    Martel, C.J.

    1987-01-01

    The purpose of this study was to develop design criteria for a new sludge dewatering unit operation called a sludge freezing bed. This bed uses natural freeze-thaw to condition the sludge for dewatering. The total depth of sludge which can be frozen, thawed and dewatered by this process in a year is the main criterion needed for design. The essential features of a freezing bed which would optimize natural freeze-thaw were identified through a literature review and site visits. Several laboratory tests were conducted to assess the dewaterability of freeze-thaw conditioned sludge at various depths. Water treatment plant sludge and both anaerobically and aerobically digested wastewater sludges were used in these tests. Mathematical models for predicting the design depth were developed and validated with data from other sludge freezing operations. Values for the input parameters to the models were obtained from the literature or from laboratory and pilot-scale experiments.

  12. Modeling frost heave in freezing soils

    Microsoft Academic Search

    Leonid Bronfenbrener; Regina Bronfenbrener

    2010-01-01

    A generalized model for secondary frost heave in freezing fine-grained soils is presented. The cryostatic suction effect, which causes an increase in upward water permeation, ice-lens growth during freezing, and, as a consequence, the increase of soil heave, is considered to be the main mechanism of moisture transfer. Although the model in this paper has a number of approaches in

  13. 40 CFR 142.57 - Bottled water, point-of-use, and point-of-entry devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    (a) A State may require a public water system to use bottled water, point-of-use devices, or point-of-entry devices as a condition of granting an exemption from the requirements of §§ 141.61 (a) and (c), and 141.62 of this...

  14. 40 CFR 142.57 - Bottled water, point-of-use, and point-of-entry devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    (a) A State may require a public water system to use bottled water, point-of-use devices, or point-of-entry devices as a condition of granting an exemption from the requirements of §§ 141.61 (a) and (c), and 141.62 of this...

  15. 40 CFR 142.57 - Bottled water, point-of-use, and point-of-entry devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    (a) A State may require a public water system to use bottled water, point-of-use devices, or point-of-entry devices as a condition of granting an exemption from the requirements of §§ 141.61 (a) and (c), and 141.62 of this...

  16. Ground-water movement and water quality in Lake Point, Tooele County, Utah, 1999-2003

    USGS Publications Warehouse

    Kenney, T.A.; Wright, S.J.; Stolp, B.J.

    2006-01-01

    Water-level and water-quality data in Lake Point, Tooele County, Utah, were collected during August 1999 through August 2003. Water levels in Lake Point generally declined about 1 to 2 feet from July 2001 to July 2003, likely because of less-than-average precipitation. Ground water generally flows in two directions from the Oquirrh Mountains. One component flows north toward the regional topographic low, Great Salt Lake. The other component generally flows southwest toward a substantial spring complex, Factory/Dunne's Pond. This southwest component flows through a coarse gravel deposit believed to be a shoreline feature of historic Lake Bonneville. The dominant water-quality trend in Lake Point is an increase in dissolved-solids concentration with proximity to Great Salt Lake. The water type changes from calcium-bicarbonate adjacent to the Oquirrh Mountains to sodium-chloride with proximity to Great Salt Lake. Evaluation of chloride-bromide weight ratios indicates a mixture of fresher recharge waters with a brine similar to what currently exists in Great Salt Lake.

  17. Elimination of bicarbonate interference in the binding of U(VI) in mill-waters to freeze-dried Chlorella vulgaris

    SciTech Connect

    Greene, B.; Henzl, M.T.; Hosea, J.M.; Darnall, D.W.

    1986-01-01

    Freeze-dried preparations of Chlorella vulgaris will accumulate U(Vl) from alkaline, bicarbonate-containing waters collected from uranium mill process streams, provided that the pH is pre-adjusted to between 4.0 and 6.0. Bicarbonate ion complexes the uranyl ion in these waters and seriously interferes with the binding of U(Vl) to the algal cells at pH values above 6.0. No binding of U(Vl) to the algae occurred at the natural pH of 8.0 when Chlorella vulgaris was suspended in untreated mull-waters containing up to 2.5 x 10/sup -4/M U(Vl). However, when the pH of these waters was lowered from 8.0 to near 5.0, with nitric acid, nearly quantitative binding of U(Vl) to the alga was achieved. Binding is rapid and largely unaffected by ions including Na/sup +/, Cl/sup -/, NO/sub 3//sup -/, /sup -/OAc, and SO/sub 4//sup 2 -/. Our results indicate that provided steps are taken to eliminate bicarbonate interference, such as adjustment of the pH to near 5.0, dried algal biomass could prove useful for the removal and recovery of U(Vl) from high carbonate-containing waters.

  18. Deliquescence and freezing of stratospheric aerosol observed by balloonborne backscattersondes

    NASA Astrophysics Data System (ADS)

    Larsen, Niels; Rosen, James M.; Kjome, Norman T.; Knudsen, Bjorn

    1995-05-01

    Stratospheric sulfate aerosols, originating from the Mt. Pinatubo volcanic eruption, have been observed during three winters in the Arctic by balloonborne backscattersondes. A measured color index, defined as the quotient between the aerosol backscatter ratios at wavelengths 940 and 480 nm, provides information of the size of the observed particles. The effects of liquid particle growth, by water vapor uptake, clearly show up as changes in the color index, whereas measurements on other days indicate the particles to be frozen. Air parcel trajectories have been calculated, providing the temperature history of the observed particles. Evidences appear of a temperature hysteresis in the freezing and melting cycle of the aerosol, indicating melting temperatures around 215-220 K in good agreement with laboratory measurements, and freezing of the particles within less than 5 K above the ice frost point. The changes in color index of the liquid particles are in good agreement with predictions from theoretical model calculations of growth by water vapor uptake.

  19. Reptile freeze tolerance: metabolism and gene expression.

    PubMed

    Storey, Kenneth B

    2006-02-01

    Terrestrially hibernating reptiles that live in seasonally cold climates need effective strategies of cold hardiness to survive the winter. Use of thermally buffered hibernacula is very important but when exposure to temperatures below 0 degrees C cannot be avoided, either freeze avoidance (supercooling) or freeze tolerance strategies can be employed, sometimes by the same species depending on environmental conditions. Several reptile species display ecologically relevant freeze tolerance, surviving for extended times with 50% or more of their total body water frozen. The use of colligative cryoprotectants by reptiles is poorly developed but metabolic and enzymatic adaptations providing anoxia tolerance and antioxidant defense are important aids to freezing survival. New studies using DNA array screening are examining the role of freeze-responsive gene expression. Three categories of freeze responsive genes have been identified from recent screenings of liver and heart from freeze-exposed (5h post-nucleation at -2.5 degrees C) hatchling painted turtles, Chrysemys picta marginata. These genes encode (a) proteins involved in iron binding, (b) enzymes of antioxidant defense, and (c) serine protease inhibitors. The same genes were up-regulated by anoxia exposure (4 h of N2 gas exposure at 5 degrees C) of the hatchlings which suggests that these defenses for freeze tolerance are aimed at counteracting the injurious effects of the ischemia imposed by plasma freezing. PMID:16321368

  20. Water Triple-Point Comparisons: Plateau Averaging or Peak Value?

    NASA Astrophysics Data System (ADS)

    Steur, P. P. M.; Dematteis, R.

    2014-04-01

    With a certain regularity, national metrology institutes conduct comparisons of water triple-point (WTP) cells. The WTP is the most important fixed point for the International Temperature Scale of 1990 (ITS-90). In such comparisons, it is common practice to simply average all the single measured temperature points obtained on a single ice mantle. This practice is quite reasonable whenever the measurements show no time dependence in the results. Ever since the first Supplementary Information for the International Temperature Scale of 1990, published by the Bureau International des Poids et Mesures in Sèvres, it was strongly suggested to wait at least 1 day before taking measurements (now up to 10 days), in order for a newly created ice mantle to stabilize. This stabilization is accompanied by a change in temperature with time. A recent improvement in the sensitivity of resistance measurement enabled the Istituto Nazionale di Ricerca Metrologica to detect more clearly the (possible) change in temperature with time of the WTP on a single ice mantle, as for old borosilicate cells. A limited investigation was performed where the temperature of two cells was monitored day-by-day, from the moment of mantle creation, where it was found that with (old) borosilicate cells it may be counterproductive to wait the usual week before starting measurements. The results are presented and discussed, and it is suggested to adapt the standard procedure for comparisons of WTP cells allowing for a different data treatment with (old) borosilicate cells, because taking the temperature dependence into account will surely reduce the reported differences between cells.

  1. An Improved Microscope Stage for Direct Observation of Freezing and Freeze Drying

    Microsoft Academic Search

    Steven L. Nail; Lih-Min Her; Christopher P. B. Proffitt; Lisa L. Nail

    1994-01-01

    A microscope stage for observation of freezing and freeze drying is described. The stage uses thermoelectric (Peltier) heaters configured in two stages, with circulating fluid as a heat sink on the high temperature side. Lowest attainable sample temperature is about -47°C. Principal advantages of this system are closed-loop control of stage temperature, rapid response to changes in temperature set point,

  2. Freezing rate and duration determine the physiological response of intertidal fucoids to freezing

    Microsoft Academic Search

    G. A. Pearson; I. R. Davison

    1993-01-01

    Differential thermal analysis (DTA) was used to measure the freezing temperature of nine species of red brown intertidal macroalgae from the coast of Maine, USA in 1991. Using slow and rapid cooling rates approximating those found in the field for Ascophyllum nodosum (L.) Le Jol. we found that, for a given rate, the freezing points of all species were similar:

  3. Liquid-vapor fractionation of oxygen and hydrogen isotopes of water from the freezing to the critical temperature

    Microsoft Academic Search

    Juske Horita; David J. Wesolowski

    1994-01-01

    The equilibrium fractionation factors of oxygen and hydrogen isotopes between liquid water and water vapor have been precisely determined from 25 to 350°C on the VSMOW-SLAP scale, using three different types of apparatus with static or dynamic techniques for the sampling of water vapor. Our results for both oxygen and hydrogen isotope fractionation factors between 25 and 100°C are in

  4. Influence of surface groups of proteins on water studied by freezing/thawing hysteresis and infrared spectroscopy

    E-print Network

    Sharp, Kim

    and melting of water was measured by infrared (IR) spectroscopy. Of the solutes examined, poly-L-arginine bands of antifreeze protein and poly-L- arginine do not detectably change with the phase transition of water. An interpretation is that the antifreeze protein and poly-L-arginine order liquid water

  5. RAPID COMMUNICATION: A technique for in situ measurement of the conductivity of water in `triple point of water' cells

    Microsoft Academic Search

    Mark Ballico

    1999-01-01

    Sealed glass ampoules made for the realization of the triple point of water as a thermometric reference point, 0.01 °C, must be filled with water of the highest possible purity. This paper discusses a simple electrical technique for measurement of the conductivity of high-purity water within such cells, and presents calculations of the calibration factor in this geometry. The technique

  6. Theory and numerical application of subsurface flow and transport for transient freezing conditions

    SciTech Connect

    White, M.D. [Pacific Northwest Lab., Richland, WA (United States). Earth and Environmental Sciences Center

    1995-04-01

    Protective barriers are being investigated for the containment of radioactive waste within subsurface environments. Predicting the effectiveness of cryogenic barriers and near-surface barriers in temperate or arctic climates requires capabilities for numerically modeling subsurface flow and transport for freezing soil conditions. A predictive numerical model is developed herein to simulate the flow and transport of radioactive solutes for three-phase (water-ice-air) systems under freezing conditions. This physically based model simulates the simultaneous flow of water, air, heat, and radioactive solutes through variably saturated and variably frozen geologic media. Expressions for ice (frozen water) and liquid water saturations as functions of temperature, interfacial pressure differences, and osmotic potential are developed from nonhysteretic versions of the Brooks and Corey and van Genuchten functions for soil moisture retention. Aqueous relative permeability functions for variably saturated and variably frozen geologic media are developed from the Mualem and Burdine theories for predicting relative permeability of unsaturated soil. Soil deformations, caused by freezing and melting transitions, are neglected. Algorithms developed for predicting ice and liquid water saturations and aqueous-phase permeabilities were incorporated into the finite-difference based numerical simulator STOMP (Subsurface Transport Over Multiple Phases). Application of the theory is demonstrated by the solution of heat and mass transport in a horizontal cylinder of partially saturated porous media with differentially cooled ends, with the colder end held below the liquid water freezing point. This problem represents an essential capability for modeling cryogenic barriers in variably saturated geologic media.

  7. INTERNATIONAL COMPARISON OF WATER TRIPLE POINT CELLS LEADING TO A MORE PRECISE DEFINITION OF THE KELVIN

    Microsoft Academic Search

    Michael Stock; Stéphane Solve

    The water triple point serves to define the kelvin, the unit of thermodynamic temperature, in the International System of Units (SI) and it is the most important temperature fixed point in the International Temperature Scale of 1990 (ITS-90). The International Bureau of Weights and Measures (BIPM) has carried out an international comparison of water triple point cells from twenty National

  8. KEY COMPARISON: Final Report on CCT-K7: Key comparison of water triple point cells

    Microsoft Academic Search

    M. Stock; S. Solve; D. del Campo; V. Chimenti; E. Méndez-Lango; H. Liedberg; P. P. M. Steur; P. Marcarino; R. Dematteis; E. Filipe; I. Lobo; K. H. Kang; K. S. Gam; Y.-G. Kim; E. Renaot; G. Bonnier; M. Valin; R. White; T. D. Dransfield; Y. Duan; Y. Xiaoke; G. Strouse; M. Ballico; D. Sukkar; M. Arai; A. Mans; M. de Groot; O. Kerkhof; R. Rusby; J. Gray; D. Head; K. Hill; E. Tegeler; U. Noatsch; S. Duris; H. Y. Kho; S. Ugur; A. Pokhodun; S. F. Gerasimov

    2006-01-01

    The triple point of water serves to define the kelvin, the unit of thermodynamic temperature, in the International System of Units (SI). Furthermore, it is the most important fixed point of the International Temperature Scale of 1990 (ITS-90). Any uncertainty in the realization of the triple point of water contributes directly to the measurement uncertainty over the wide temperature range

  9. Groundwater flow with energy transport and water-ice phase change: Numerical simulations, benchmarks, and application to freezing in peat bogs

    USGS Publications Warehouse

    McKenzie, J.M.; Voss, C.I.; Siegel, D.I.

    2007-01-01

    In northern peatlands, subsurface ice formation is an important process that can control heat transport, groundwater flow, and biological activity. Temperature was measured over one and a half years in a vertical profile in the Red Lake Bog, Minnesota. To successfully simulate the transport of heat within the peat profile, the U.S. Geological Survey's SUTRA computer code was modified. The modified code simulates fully saturated, coupled porewater-energy transport, with freezing and melting porewater, and includes proportional heat capacity and thermal conductivity of water and ice, decreasing matrix permeability due to ice formation, and latent heat. The model is verified by correctly simulating the Lunardini analytical solution for ice formation in a porous medium with a mixed ice-water zone. The modified SUTRA model correctly simulates the temperature and ice distributions in the peat bog. Two possible benchmark problems for groundwater and energy transport with ice formation and melting are proposed that may be used by other researchers for code comparison. ?? 2006 Elsevier Ltd. All rights reserved.

  10. Freezing temperatures of aqueous iron(III) sulfate solutions and crystallization of a new acidic water-rich sulfate

    NASA Astrophysics Data System (ADS)

    Hennings, E.; Zürner, P.; Schmidt, H.; Voigt, W.

    2013-09-01

    An important question concerning the possibility of life under martian conditions is the existence of liquid water at low temperatures. On the martian surface, the existence of iron(III) sulfate is expected. The influence of iron(III) sulfate salt on ice deposits in respect to the formation of liquid salt brines was not investigated in the past. In this contribution, the investigation of the phase diagram of the system iron(III) sulfate-water and the influence of sulfuric acid to this system are presented. A new crystalline acidic iron(III) sulfate hydrate has been found in the ternary system iron(III) sulfate-water-sulfuric acid, which represents the most water-rich iron salt phase ever detected.

  11. A new definition of the logarithmic temperature scale based on the triple point of water

    Microsoft Academic Search

    JULIO PELLICER; MARÍA-JESÚS HERNÁNDEZ; MANUEL DOLZ

    Using the triple point of water a.s a fixed point, a logarithmic temperature scale is defined. After establishing the relation between this scale and the thermodynamic scale, its scientific and academic advantages at low temperaturc are stated.

  12. EURAMET.TK7 Key Comparison of Water Triple-Point Cells

    Microsoft Academic Search

    A. Peruzzi; R. Bosma; O. Kerkhof; P. Rosenkranz; M. D. Del Campo Maldonado; R. Strnad; J. Nielsen; M. Anagnostou; T. Veliki; D. Zvizdic; E. Grudnewicz; M. Nedea; D. M. Neagu; P. Steur; E. Filipe; I. Lobo; I. Antonsen; E. Renaot; M. Heinonen; T. Weckstrom; J. Bojkovski; E. Turzo-Andras; S. Nemeth; M. White; E. Tegeler; M. Dobre; S. Duris; A. Kartal Dogan; A. Uytun; V. Augevicius; A. Pokhodun; S. Simic

    2011-01-01

    The results of a EURAMET key comparison of water triple-point cells (EURAMET.T-K7) are reported. The equipment used, the measuring\\u000a conditions applied, and the procedures adopted for the water triple-point measurement at the participating laboratories are\\u000a synthetically presented. The definitions of the national reference for the water triple-point temperature adopted by each\\u000a laboratory are disclosed. The multiplicity of degrees of equivalence

  13. Sensitivity of liquid clouds to homogenous freezing parameterizations

    PubMed Central

    Herbert, Ross J; Murray, Benjamin J; Dobbie, Steven J; Koop, Thomas

    2015-01-01

    Water droplets in some clouds can supercool to temperatures where homogeneous ice nucleation becomes the dominant freezing mechanism. In many cloud resolving and mesoscale models, it is assumed that homogeneous ice nucleation in water droplets only occurs below some threshold temperature typically set at ?40°C. However, laboratory measurements show that there is a finite rate of nucleation at warmer temperatures. In this study we use a parcel model with detailed microphysics to show that cloud properties can be sensitive to homogeneous ice nucleation as warm as ?30°C. Thus, homogeneous ice nucleation may be more important for cloud development, precipitation rates, and key cloud radiative parameters than is often assumed. Furthermore, we show that cloud development is particularly sensitive to the temperature dependence of the nucleation rate. In order to better constrain the parameterization of homogeneous ice nucleation laboratory measurements are needed at both high (>?35°C) and low (Points Homogeneous freezing may be significant as warm as ?30°C Homogeneous freezing should not be represented by a threshold approximation There is a need for an improved parameterization of homogeneous ice nucleation PMID:26074652

  14. Thermal Analysis of the Tertiary Butyl Alcohol-Water System and Its Implications on Freeze-Drying

    Microsoft Academic Search

    Kasra Kasraian; Patrick P. DeLuca

    1995-01-01

    Utilizing differential scanning calorimetry (DSC) for tertiary butyl alcohol (TBA) solutions a phase diagram was constructed for the TBA-water system. By utilizing thermal treatment during the DSC measurements the metastable states were eliminated. The phase diagram fit that for a congruently melting compound in which compound formation occurred with a maximum at 70% TBA representing pure TBA hydrate. Two eutectics

  15. Soil salinity increases survival of freezing in the enchytraeid Enchytraeus albidus.

    PubMed

    Silva, A L Patrício; Holmstrup, M; Kostal, V; Amorim, M J B

    2013-07-15

    Enchytraeus albidus is a freeze-tolerant enchytraeid found in diverse habitats, ranging from supralittoral to terrestrial and spanning temperate to arctic regions. Its freeze tolerance is well known but the effect of salinity in this strategy is still poorly understood. We therefore studied the combined effect of salinity (0, 15, 35, 50‰ NaCl) and sub-zero temperatures (-5, -14, -20°C) on the freeze tolerance of E. albidus collected from two distinct geographical regions (Greenland and Germany). A full factorial design was used to study survival, and physiological and biochemical end points. The effect of salinity on the reproduction of German E. albidus was also assessed. Exposure for 48 h to saline soils prior to cold exposure triggered an increase in osmolality and decrease in water content. Worms exposed to saline soils had an improved survival of freezing compared to worms frozen in non-saline soils, particularly at -20°C (survival more than doubled). Differential scanning calorimetry measurements showed that the fraction of water frozen at -5 and -14°C was lower in worms exposed to 35‰ NaCl than in control worms. The lowering of ice content by exposure to saline soils was probably the main explanation for the better freeze survival in saline-exposed worms. Glucose increased with decreasing temperature, but was lower in saline than in non-saline soils. Thus, glucose accumulation patterns did not explain differences in freeze survival. Overall, the physiological responses to freezing of E. albidus from Greenland and Germany were similar after exposure to saline soils. Soil salinity up to 30‰ improved reproduction by a factor of ca. 10. PMID:23531829

  16. Effects of Heavy Hydrogen and Oxygen on the Triple-Point Temperature of Water

    Microsoft Academic Search

    D. R. White; T. D. Dransfield; G. F. Strouse; W. L. Tew; R. L. Rusby; J. Gray

    2003-01-01

    The temperature of the triple point of water is dependent on the isotopic composition of the water. The depletion of heavy isotopes arising from the use of fresh water rather than seawater, and from distillation and degassing of the water during manufacture of the cells, leads to cells realizing temperatures up to 80 muK lower than the definition. Five cells

  17. Effects of Heavy Hydrogen and Oxygen on the Triple-Point Temperature of Water

    Microsoft Academic Search

    D. R. White; T. D. Dransfield; G. F. Strouse; W. L. Tew; R. L. Rusby; J. Gray

    2003-01-01

    The temperature of the triple point of water is dependent on the isotopic composition of the water. The depletion of heavy isotopes arising from the use of fresh water rather than seawater, and from distillation and degassing of the water during manufacture of the cells, leads to cells realizing temperatures up to 80 ?K lower than the definition. Five cells

  18. Surface freezing of n-octane nanodroplets

    NASA Astrophysics Data System (ADS)

    Modak, Viraj; Pathak, Harshad; Thayer, Mitchell; Singer, Sherwin; Wyslouzil, Barbara

    2013-05-01

    Surface freezing, at temperatures up to a few degrees above the equilibrium melting point, has been observed for intermediate chain length (16? i? 50) n-alkanes [B. M. Ocko, X. Z. Wu, E. B. Sirota, S. K. Sinha, O. Gang and M. Deutsch, Phys. Rev. E, 1997, 55, 3164-3182]. Our recent experimental results suggest that surface freezing is also the first step when highly supercooled nanodroplets of n-octane crystallize. Our data yield surface and bulk nucleation rates on the order of ˜1015/cm2.s and ˜1022/cm3.s, respectively. Complementary molecular dynamics simulations also show that the surface of the droplet freezes almost immediately, and freezing of the remainder of the droplet progresses in a layer-by-layer manner.

  19. Freezing-thawing action in the deterioration of the stones of Chambord Castle

    NASA Astrophysics Data System (ADS)

    Alomari, Asaad; Brunetaud, Xavier; Beck, Kevin; Al-Mukhtar, Muzahim

    2013-04-01

    Limestone is very common in architecture (monuments and cultural heritage buildings) and used in the sculptures. The soft and porous limestone soaks up water and show weathering patterns and forms: alveolar weathering, granular disintegration, efflorescences. Freezing-thawing actions can be considered as one of the processes that contribute in the deterioration of stones located in the "cold regions" characterized with air temperatures below freezing point temperature. The amount of water within the pore space of the stones is a crucial factor of the decay. The experimental work presented in this paper is a part of a research program that aims to study the mechanisms that lead to the degradation of stone building materials due to the variation of climatic conditions. The analysis of the meteorological data of the field around the castle of Chambord shows the magnitude of temperature variations and the frequency of freezing-thawing cycles. The critical degrees of saturation at which the stone start to deteriorate after treatment with freezing-thawing cycles were examined in the tests conducted. The study concerns two porous limestone used in the construction and conservation of Chambord castle; highly porous Tuffeau stone having a total porosity of about 48 %, and medium porous Richemont stone with a total porosity of 27 %. Richemont stone has been used as a substitute stone of the degraded Tuffeau stone on the castle. The main physical properties, total porosity, apparent dry density and skeleton density and sound velocity for mechanical properties were measured for the stone samples before and during freezing-thawing cycles. ASTM (D5312-04) procedure was applied in the freezing-thawing tests. Tuffeau and Richmond samples were prepared at nine different degrees of saturations; 0, 20, 40, 70, 80, 85, 90, 95 and 100%, and properties were measured after different freezing-thawing cycles conditions; 2, 4, 8, 12, 16, 20, 30 and 50 cycles. The results of these tests show that when the degree of saturation exceeds 80-85%, freeze-thaw damage is inevitable even for a very few freeze-thaw cycles. Moreover, results indicate that the two studied stones have similar critical degree of saturation of about 85 %. This can be attributed to the similar percentage of macro-pores in the two tested stones. Finally, the critical degree of saturation was not changed after increasing the number of freezing-thawing cycles, thus the critical degree of saturation can be considered as a stone property.

  20. Freeze drying method

    SciTech Connect

    Coppa, N.V.; Stewart, P.; Renzi, E.

    1999-12-07

    The present invention provides methods and apparatus for freeze drying in which a solution, which can be a radioactive salt dissolved within an acid, is frozen into a solid on vertical plates provided within a freeze drying chamber. The solid is sublimated into vapor and condensed in a cold condenser positioned above the freeze drying chamber and connected thereto by a conduit. The vertical positioning of the cold condenser relative to the freeze dryer helps to help prevent substances such as radioactive materials separated from the solution from contaminating the cold condenser. Additionally, the system can be charged with an inert gas to produce a down rush of gas into the freeze drying chamber to also help prevent such substances from contaminating the cold condenser.

  1. HACCP (Hazard Analysis and Critical Control Points) to guarantee safe water reuse and drinking water production - a case study

    Microsoft Academic Search

    T. Dewettinck; E. Van Houtte; D. Geenens; K. Van Hege; W. Verstraete

    2001-01-01

    To obtain a sustainable water catchment in the dune area of the Flemish west coast, the integration of treated domestic wastewater in the existing potable water production process is planned. The hygienic hazards associated with the introduction of treated domestic wastewater into the water cycle are well recognised. Therefore, the concept of HACCP (Hazard Analysis and Critical Control Points) was

  2. Exploring the Nature of Contact Freezing

    NASA Astrophysics Data System (ADS)

    Kiselev, A. A.; Hoffmann, N.; Duft, D.; Leisner, T.

    2012-12-01

    The freezing of supercooled water droplets upon contact with aerosol particles (contact nucleation of ice) is the least understood mechanism of ice formation in atmospheric clouds. Although experimental evidences suggest that some aerosols can be better IN in the contact than in the immersion mode (that is, triggering ice nucleation at higher temperature), no final explanation of this phenomena currently exists. On the other hand, the contact freezing is believed to be responsible for the enhanced rate of secondary ice formation occasionally observed in LIDAR measurements in the cold mixed phase clouds. Recently we have been able to show that the freezing of supercooled droplets electrodynamically levitated in the laminar flow containing mineral dust particles (kaolinite) is a process solely governed by a rate of collisions between the supercooled droplet and the aerosol particles. We have shown that the probability of droplet freezing on a single contact with aerosol particle may differ over an order of magnitude for kaolinite particles having different genesis and morphology. In this presentation we extend the study of contact nucleation of ice and compare the IN efficiency measured for DMA-selected kaolinite, illite and hematite particles. We show that the freezing probability increases towards unity as the temperature decreases and discuss the functional form of this temperature dependence. We explore the size dependence of the contact freezing probability and show that it scales with the surface area of the particles, thus resembling the immersion freezing behavior. However, for all minerals investigated so far, the contact freezing has been shown to dominate over immersion freezing on the short experimental time scales. Finally, based on the combined ESEM and electron microprobe analysis, we discuss the significance of particle morphology and variability of chemical composition on its IN efficiency in contact mode.

  3. Identification and quantification of point sources of surface water contamination in fruit culture in the Netherlands

    Microsoft Academic Search

    M. Wenneker; W. H. J. Beltman; Werd de H. A. E; Zande van de J. C

    2008-01-01

    Measurements of pesticide concentrations in surface water by the water boards show that they have decreased less than was expected from model calculations. Possibly, the implementation of spray drift reducing techniques is overestimated in the model calculation. The impact of point sources is probably underestimated. A project was initiated for the quantification and qualification of possible point sources in Dutch

  4. HydroSense: Infrastructure-Mediated Single-Point Sensing of Whole-Home Water Activity

    E-print Network

    Anderson, Richard

    Sense, a low-cost and easily-installed single-point sensor of pressure within a home's water infrastructure HydroSense, a low-cost, single-point solution for activity sensing mediated by a home's existing water-mediated sensing as a practical, low-cost, and unobtrusive approach to sensing human activity in the physical world

  5. Vapor Pressure of Water at Its Triple Point: Highly Accurate Value

    Microsoft Academic Search

    L. A. Guildner; D. P. Johnson; F. E. Jones

    1976-01-01

    The vapor pressure of water at its triple point was measured with greatly increased accuracy. The triple point was realized with newly designed equipment that enhanced the stability of the pressure and permitted any air released from solution to be removed by pumping. A diaphragm pressure transducer separated the water vapor from the helium used to transmit the pressure to

  6. Results of an international comparison of water triple-point cells

    Microsoft Academic Search

    R. Pello; R. Goebel; R. Köhler

    1997-01-01

    The reference temperatures of a large number of triple point of water cells collected from manufacturing sources around the world have been compared at the BIPM and in twelve national laboratories. This allowed an assessment to be made of the reproducibility of the realizations of the triple point of water and the equivalence of the experimental procedures. The results show

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

    E-print Network

    A Fixed Point Charge Model for Water Optimized to the Vapor-Liquid Coexistence Properties Jeffrey R@ipst.umd.edu #12;1 Abstract A new fixed-point charge potential model for water has been developed, targeting the accurate prediction of the vapor-liquid coexistence properties over a broad temperature range. The model

  8. Use of the Triple Point of Water and Melt Point of Gallium Cells as Standards at Sea

    Microsoft Academic Search

    1987-01-01

    Triple point of water and gallium melt cells may prove very useful at sea for the calibrations checks demanded of high accuracy free-fall type CTD platforms being developed for the World Ocean Circulation Experiment program of deep ocean study. In ship's motion simulations at ENDECO, Inc., standards mounted on a pendulum platform showed no detectable temperature shifts due to low

  9. Metabolomics for in situ environmental monitoring of surface waters impacted by contaminants from both point and non-point sources

    EPA Science Inventory

    We investigated the efficacy of metabolomics for field-monitoring of fish exposed to waste water treatment plant (WWTP) effluents and non-point sources of chemical contamination. Lab-reared male fathead minnows (Pimephales promelas, FHM) were held in mobile monitoring units and e...

  10. A Comparative Risk Approach to Assessing Point-of-Use Water treatment Systems in Developing Countries

    Microsoft Academic Search

    A. Varghese

    Unsafe water is a leadingcause of death and disease in economically disadvantaged societies. The development of centralized large-scale water treatment and supply systems has proven to be a slow, expensive strategy to provide safe drinking water in many low-income countries. Governments and non-governmental organizations have therefore increasingly been promoting point-of-use water treatment technologies in communities without reliable municipal water supplies.

  11. Inhibition of heavy metal ion corrosion on aluminum in fresh water cooling systems using propylene glycol anti-freeze

    SciTech Connect

    Hack, H.P. [Northrop Grumman Corp., Annapolis, MD (United States). Electronic Sensors and Systems Div.; Corbett, R.; Krantz, B. [Corrosion Testing Labs., Newark, DE (United States)

    1998-12-31

    Electronics cooling and environmental control systems are required in enclosed manned spaces such as the inside of spacecraft or submersibles. Because egress from such spaces may not be possible in a short time frame, coolant leaks must have minimum toxicity. For this reason, propylene glycol coolants are preferred over the traditional ethylene glycol coolants. Corrosion inhibitor formulations are well developed for ethylene glycol coolants, but there is concern that the inhibitor suite for propylene glycol systems may not be as mature. In particular, coolant systems with a mixture of aluminum and copper can develop heavy metal ion corrosion of the aluminum due to precipitation of copper ions from solution onto the aluminum. This type of accelerated corrosion of aluminum does not require electrical contact with copper, as is the case for galvanic corrosion, nor is significant coolant conductivity required for corrosion to occur. This paper presents a study of the ability of a commercial inhibited propylene glycol coolant to prevent heavy metal ion corrosion of aluminum when copper is also present in the coolant system. The inhibited propylene glycol`s performance is compared to that of reagent propylene glycol without inhibitors, a mature ethylene glycol inhibited coolant, and to tap water. The inhibitor suite in the inhibited propylene glycol was found to be as effective in controlling heavy metal ion corrosion as that of the inhibited ethylene glycol coolant, while uninhibited reagent propylene glycol was ineffective in controlling heavy metal ion corrosion.

  12. VSMOW Triple Point of Water Cells: Borosilicate versus Fused-Quartz

    Microsoft Academic Search

    M. Zhao; G. F. Strouse

    2007-01-01

    To investigate an ideal container material for the triple point of water (TPW) cell and to reduce the influence to the triple-point\\u000a temperature, due to the deviation of the isotopic composition of the water, both borosilicate and fused-quartz glass shelled\\u000a TPW cells with isotopic composition substantially matching that of Vienna Standard Mean Ocean Water (VSMOW) were developed\\u000a and tested. Through

  13. Study on Freezing of a Single Droplet

    NASA Astrophysics Data System (ADS)

    Fumoto, Koji; Yamagishi, Hideaki; Ikegawa, Masahiro

    The freezing characteristics of a single water droplet placed on the column edge were visually investigated using a video camera. The temperatures of the edge face and the environment air were independently controlled. The solidification process of the water droplet was discussed based on the many pictures obtained. The experimental results indicated that the freezing time of droplet was strongly affected by the edge temperature. Furthermore, we found that the water dispersion thermosensitivity slurry was effective for the observation of the temperature of the droplet. Consequently, it was indicated that the heat transfer characteristics of the droplet under freezing condition were mainly affected by both temperature of the air and surface of the flat plate.

  14. EVALUATING POINT-NONPOINT SOURCE WATER QUALITY TRADING IN A RARITAN RIVER BASIN SUB-WATERSHED

    EPA Science Inventory

    This project addresses water quality issues in the Raritan River Basin of New Jersey. It will build upon an existing study that determined the technical feasibility of implementing a point-nonpoint source water quality trading program in the Basin. Water quality trading is ...

  15. Integrated watershed approach in controlling point and non-point source pollution within Zelivka drinking water reservoir.

    PubMed

    Holas, J; Hrncir, M

    2002-01-01

    An agricultural watershed involves manipulation of soil, water and other natural resources and it has profound impacts on ecosystems. To manage these complex issues, we must understand causes and consequences and interactions-related transport of pollutants, quality of the environment, mitigation measures and policy measures. A ten year period of economic changes has been analysed with respect to sustainable development concerning Zelivka drinking water reservoir and its watershed, where agriculture and forestry are the main human activities. It is recommended that all land users within a catchment area should receive payments for their contribution to water cycle management. Setting up the prevention principles and best management practices financially subsidized by a local water company has been found very effective in both point and non-point source pollution abatement, and the newly prepared Clean Water Programme actively involves local municipal authorities as well. The first step based on systems analysis was to propose effective strategies and select alternative measures and ways for their financing. Long term monitoring of nutrient loads entering the reservoir and hazardous events statistics resulted in maps characterising the territory including vulnerable zones and risk factors. Financing involves providing annual payments to farmers, who undertake to manage specified areas of their land in a particular way and one-off payments to realise proposed issues ensuring soil conservation and watershed ecosystem benefits. PMID:12079117

  16. Soil water repellency of Antarctic soils (Elephant Point). First results

    NASA Astrophysics Data System (ADS)

    Pereira, Paulo; Oliva, Marc; Ruiz Fernández, Jesus

    2015-04-01

    Hydrophobicity it is a natural properties of many soils around the world. Despite the large body of research about soil water hydrophobicity (SWR) in many environments, little information it is available about Antarctic soils and their hydro-geomorphological consequences. According to our knowledge, no previous work was carried out on this environment. Soil samples were collected in the top-soil (0-5 cm) and SWR was analysed according to the water drop penetration test. The preliminary results showed that all the soils collected were hydrophilic, however further research should be carried out in order to understand if SWR changes with soil depth and if have implications on soil infiltration during the summer season.

  17. Building the water edge : a public event for art and artists at Fort Point Channel

    E-print Network

    Godwin, Audrey

    1996-01-01

    The thesis deals with building the water edge at Fort Point Channel, between Congress Street and Summer Street Bridges. It serves as a public event that intends to establish continuity of movement along the waterfront. The ...

  18. Study of preparation of ice mantles of triple point of water cells

    Microsoft Academic Search

    K. Kodaira

    2002-01-01

    Ice mantles of triple point of water cells were prepared by a new technique using a remodeled refrigerator with a circulation pump. The work was completed within approximately 10 minutes. No cracks were formed in ice mantles during the preparation.

  19. Effects of Heavy Hydrogen and Oxygen on the Triple-Point Temperature of Water

    NASA Astrophysics Data System (ADS)

    White, D. R.; Dransfield, T. D.; Strouse, G. F.; Tew, W. L.; Rusby, R. L.; Gray, J.

    2003-09-01

    The temperature of the triple point of water is dependent on the isotopic composition of the water. The depletion of heavy isotopes arising from the use of fresh water rather than seawater, and from distillation and degassing of the water during manufacture of the cells, leads to cells realizing temperatures up to 80 ?K lower than the definition. Five cells of varying isotopic composition were compared to evaluate the practicality of applying corrections for isotopic composition. It was found that the correction constants for deuterium and 18O measured previously by Kiyosawa were consistent with the measurements of the cells. Both of the correction constants are larger than predicted by interpolation between the triple-point temperatures of the pure isotopomers. Application of the corrections for isotopic composition eliminates a significant bias in the triple-point temperature and reduces the uncertainty in the triple-point temperature due to isotopic composition from ±40 ?K to better than ±3 ?K.

  20. Freeze-drying of lactic acid bacteria.

    PubMed

    Fonseca, Fernanda; Cenard, Stéphanie; Passot, Stéphanie

    2015-01-01

    Lactic acid bacteria are of great importance for the food and biotechnology industry. They are widely used as starters for manufacturing food (e.g., yogurt, cheese, fermented meats, and vegetables) and probiotic products, as well as for green chemistry applications. Freeze-drying or lyophilization is a convenient method for preservation of bacteria. By reducing water activity to values below 0.2, it allows long-term storage and low-cost distribution at suprazero temperatures, while minimizing losses in viability and functionality. Stabilization of bacteria via freeze-drying starts with the addition of a protectant solution to the bacterial suspension. Freeze-drying includes three steps, namely, (1) freezing of the concentrated and protected cell suspension, (2) primary drying to remove ice by sublimation, and (3) secondary drying to remove unfrozen water by desorption. In this chapter we describe a method for freeze-drying of lactic acid bacteria at a pilot scale, thus allowing control of the process parameters for maximal survival and functionality recovery. PMID:25428024

  1. KEY COMPARISON: Final Report on EUROMET.TK7: Key comparison of water triple point cells

    Microsoft Academic Search

    A. Peruzzi; R. Bosma; O. Kerkhof; R. Peter; M. D. del Campo Maldonado; M. Smid; D. Zvizdic; M. B. Nielsen; M. Anagnostou; E. Grudnewicz; M. Nedea; P. P. M. Steur; E. Filipe; I. Lobo; I. Antonsen; E. Renaot; T. Weckstrom; J. Bojkovski; E. Turzó-András; M. White; E. Tegeler; M. Dobre; J. Ranostaj; A. Kartal Dogan; V. Augevicius; A. Pokhodun; S. Simic

    2009-01-01

    From 2002 to 2004 the Consultative Committee for Thermometry (CCT) carried out a Key Comparison (KC) of water triple point cells (CCT-K7). In 2005 the Regional Metrology Organization (RMO) EURAMET decided to initiate an additional KC of water triple point cells, EUROMET.T-K7, to extend the metrological equivalence to a larger number of national metrology institutes (NMIs) from the EURAMET region.

  2. The Long-Term Drift of Triple-Point-of-Water Cells

    Microsoft Academic Search

    X. K. Yan; C. F. Ma; Z. Zhang; H. L. Wu; P. Qiu; Y. L. Feng; J. T. Zhang; Y. N. Duan

    2008-01-01

    As the triple point of water is of great importance for the International Temperature Scale of 1990 (ITS-90) and for the definition of the unit of thermodynamic temperature, its long-term stability has attracted a great deal of attention. In a study of long-term stability, a mystery has been uncovered. Some triple-point-of-water cells remain stable for many decades, while others decrease

  3. The preparation and use of cells for the realization of the triple point of water

    Microsoft Academic Search

    C R Barber; R Handley; E F G Herington

    1954-01-01

    The Ninth General Conference of Weights and Measures(1,2) which met in October 1948 passed a resolution that the zero of the International Temperature Scale should be defined as being the temperature 0.0100° C below that of the triple point of water. The technique used at Teddington for preparing cells for the realization of the triple point of water is described

  4. The Long-Term Drift of Triple-Point-of-Water Cells

    Microsoft Academic Search

    X. K. Yan; C. F. Ma; Z. Zhang; H. L. Wu; P. Qiu; Y. L. Feng; J. T. Zhang; Y. N. Duan

    2008-01-01

    As the triple point of water is of great importance for the International Temperature Scale of 1990 (ITS-90) and for the definition\\u000a of the unit of thermodynamic temperature, its long-term stability has attracted a great deal of attention. In a study of long-term\\u000a stability, a mystery has been uncovered. Some triple-point-of-water cells remain stable for many decades, while others decrease

  5. The Use of Thermowell Bushes at the Triple Point of Water for Improving Repeatability

    Microsoft Academic Search

    E. Smith; G. Machin; J. Gray; R. Veltcheva

    2010-01-01

    Water triple point cells are essential for realization of the International Temperature Scale of 1990 (ITS-90). There is some\\u000a evidence that achieving the ultimate performance of water triple point cells may be restricted by the variation in the position\\u000a of the platinum resistance thermometer at the bottom of the re-entrant well, and that the variation in position is not completely

  6. Physiological responses to freezing in hatchlings of freeze-tolerant and -intolerant turtles.

    PubMed

    Costanzo, Jon P; Baker, Patrick J; Lee, Richard E

    2006-09-01

    Freeze tolerance is a complex cold-hardiness adaptation that has independently evolved in a diverse group of organisms, including several ectothermic vertebrates. Because little is known about the mechanistic basis for freeze tolerance in reptiles, we compared responses to experimental freezing in winter-acclimatized hatchlings representing nine taxa of temperate North American turtles, including ones that tolerated freezing and others that did not. Viability rates of hatchlings frozen to -3 degrees C for 72 h ranged from 0 to 100%. Tolerance to freezing was poor in Sternotherus odoratus, Graptemys geographica and Trachemys scripta, intermediate in Chelydra serpentina, and high in Emydoidea blandingii, Chrysemys picta bellii, C. p. marginata, Malaclemys terrapin, and Terrapene ornata, and generally reflected the winter thermal ecology of each taxon. Plasma activity of lactate dehydrogenase (LDH), a novel in vivo index of freeze/thaw damage, corroborated viability assessments and demonstrated that cryoinjury occurred even in surviving turtles. Irrespective of taxon, cryoinjury tended to be higher in smaller individuals and in those having relatively low water contents; however, bases for these associations were not apparent. Screening for certain organic osmolytes that might promote freezing survival by colligatively reducing ice content and limiting cell dehydration showed that the plasma of unfrozen (control) turtles contained small quantities of glucose (1.3-5.8 mmol l(-1)) and lactate (0.6-3.2 mmol l(-1)) and modest amounts of urea (range of mean values for all taxa 8.2-52.3 mmol l(-1)). Frozen/thawed turtles of all taxa accumulated modest amounts of glucose and lactate that jointly raised the plasma solute concentration by 30-100 mmol l(-1). We conclude that organic osmolytes accumulated both before and during freezing may promote survival in species that have evolved a tolerance to freezing, but are not necessarily accumulated for that purpose. PMID:16758216

  7. AN APPROACH TO WATER RESOURCES EVALUATION OF NON-POINT SILVICULTURAL SOURCES (A PROCEDURAL HANDBOOK)

    EPA Science Inventory

    This handbook provides an analysis methodology that can be used to describe and evaluate changes to the water resource resulting from non-point silvicultural activities. This state-of-the-art approach for analysis and prediction of pollution from non point silvicultural activitie...

  8. POINT-OF-USE TREATMENT OF DRINKING WATER IN SAN YSIDRO, NM

    EPA Science Inventory

    A study was conducted to determine whether point-of-use reverse osmosis units could satisfactorily function in lieu of central treatment to remove arsenic and fluoride from the drinking water supply of a small community. Point-of-use treatment was evaluated for removal efficiency...

  9. Pointed water vapor radiometer corrections for accurate Global Positioning System surveying

    Microsoft Academic Search

    Randolph Ware; Christian Rocken; Fredrick Solheim; Teresa Van Hove; Chris Alber; James Johnson

    1993-01-01

    Delay of the Global Positioning System (GPS) signal due to atmospheric water vapor is a major source of error in GPS surveying. Improved vertical accuracy is important for sea level and polar isostasy measurements, geodesy, normal fault motion, subsidence, earthquake studies, air and ground-based gravimetry, ice dynamics, and volcanology. We conducted a GPS survey using water vapor radiometers (WVRs) pointed

  10. Automated Realization of the Triple Point of Water Using the Mush Method

    Microsoft Academic Search

    X. K. Yan; Y. N. Duan; J. H. Yang; J. Li

    2010-01-01

    In order to investigate mechanisms of phase transitions of supercooled water in a triple-point-of-water (TPW) cell when a mush method was used to create an ice mantle, an automated apparatus using small TPW cells was developed to obtain the TPW. In this article, the design principle, the apparatus, and the procedure for an automated formation of ice mantles in small

  11. Automated Realization of the Triple Point of Water Using the Mush Method

    Microsoft Academic Search

    X. K. Yan; Y. N. Duan; J. H. Yang; J. Li

    2011-01-01

    In order to investigate mechanisms of phase transitions of supercooled water in a triple-point-of-water (TPW) cell when a mush method was used to create an ice mantle, an automated apparatus using small TPW cells was developed to obtain the TPW. In this article, the design principle, the apparatus, and the procedure for an automated formation of ice mantles in small

  12. Improved Estimates of the Isotopic Correction Constants for the Triple Point of Water

    Microsoft Academic Search

    D. R. White; W. L. Tew

    2010-01-01

    In 2006, the CIPM clarified the definition of the kelvin by specifying the isotopic composition of the water to be used in the realization of the triple point. At the same time, the Consultative Committee for Thermometry gave recommended values for the isotopic correction constants to be used for water departing from the specified composition. However, the uncertainties in the

  13. Realization of the triple points of gallium, water and mercury by an adiabatic calorimetric method

    Microsoft Academic Search

    H. Sakurai

    1996-01-01

    The triple points of water, mercury and gallium are realized, mainly for the calibration of capsule-type thermometers, by a calorimetric method using platinum cells for water and mercury, and a small glass cell for gallium. Their molar impurities are estimated from the relation between the melting temperatures and the inverses of the fraction of melt. Almost all the samples show

  14. Isotopic Effects on the Temperature of the Triple Point of Water

    Microsoft Academic Search

    X. K. Yan; J. T. Zhang; Y. L. Wang; C. F. Ma; Y. N. Duan

    2008-01-01

    An investigation into the effects of isotopic composition on the triple point temperature of water has been carried out at the National Institute of Metrology (NIM), China, since redefinition of the kelvin with respect to Vienna Standard Mean Ocean Water (V-SMOW) was officially proposed by the Consultative Committee for Thermometry (CCT) in 2005. In this paper, a comparison of four

  15. Hysteresis of Soil Point Water Retention Functions Determined by Neutron Radiography

    NASA Astrophysics Data System (ADS)

    Perfect, E.; Kang, M.; Bilheux, H.; Willis, K. J.; Horita, J.; Warren, J.; Cheng, C.

    2010-12-01

    Soil point water retention functions are needed for modeling flow and transport in partially-saturated porous media. Such functions are usually determined by inverse modeling of average water retention data measured experimentally on columns of finite length. However, the resulting functions are subject to the appropriateness of the chosen model, as well as the initial and boundary condition assumptions employed. Soil point water retention functions are rarely measured directly and when they are the focus is invariably on the main drying branch. Previous direct measurement methods include time domain reflectometry and gamma beam attenuation. Here we report direct measurements of the main wetting and drying branches of the point water retention function using neutron radiography. The measurements were performed on a coarse sand (Flint #13) packed into 2.6 cm diameter x 4 cm long aluminum cylinders at the NIST BT-2 (50 ?m resolution) and ORNL-HFIR CG1D (70 ?m resolution) imaging beamlines. The sand columns were saturated with water and then drained and rewetted under quasi-equilibrium conditions using a hanging water column setup. 2048 x 2048 pixel images of the transmitted flux of neutrons through the column were acquired at each imposed suction (~10-15 suction values per experiment). Volumetric water contents were calculated on a pixel by pixel basis using Beer-Lambert’s law in conjunction with beam hardening and geometric corrections. The pixel rows were averaged and combined with information on the known distribution of suctions within the column to give 2048 point drying and wetting functions for each experiment. The point functions exhibited pronounced hysteresis and varied with column height, possibly due to differences in porosity caused by the packing procedure employed. Predicted point functions, extracted from the hanging water column volumetric data using the TrueCell inverse modeling procedure, showed very good agreement with the range of point functions measured within the column using neutron radiography. Extension of these experiments to 3-dimensions using neutron tomography is planned.

  16. Bjorken model with Freeze Out

    E-print Network

    V. K. Magas; L. P. Csernai

    2007-11-19

    The freeze out of the expanding systems, created in relativistic heavy ion collisions, is discussed. We combine Bjorken scenario with earlier developed freeze out equations into a unified model. The important feature of the proposed model is that physical freeze out is completely finished in a finite time, which can be varied from 0 (freeze out hypersurface) to infinity. The dependence of the post freeze out distribution function on this freeze out time will be studied. As an example model is completely solved and analyzed for the gas of pions.

  17. Removing Lead From Drinking Water With a Point-of-Use GAC Fixed-Bed Adsorber

    Microsoft Academic Search

    Roy W. Kuennen; Roy M. Taylor; Karl Van Dyke; Kevin Groenevelt

    1992-01-01

    An evaluation was carried out of a point-of-use (POU) granular activated carbon (GAC) fixed-bed adsorber (FBA) for removing soluble and insoluble lead from drinking water. Several factors affected the removal of lead from water by GAC, including carbon type, particle size distribution, solution pH, contact time of water with GAC, surface loading of lead onto GAC, competitive interactions with other

  18. Removal of virus to protozoan sized particles in point-of-use ceramic water filters

    Microsoft Academic Search

    Angela R. Bielefeldt; Kate Kowalski; Cherylynn Schilling; Simon Schreier; Amanda Kohler; R. Scott Summers

    2010-01-01

    The particle removal performance of point-of-use ceramic water filters (CWFs) was characterized in the size range of 0.02–100 ?m using carboxylate-coated polystyrene fluorescent microspheres, natural particles and clay. Particles were spiked into dechlorinated tap water, and three successive water batches treated in each of six different CWFs. Particle removal generally increased with increasing size. The removal of virus-sized 0.02 and 0.1 ?m

  19. Isotope and Impurity Content in Water Triple-Point Cells Manufactured at NMi VSL

    Microsoft Academic Search

    Andrea Peruzzi; O. Kerkhof; M. J. de Groot

    2007-01-01

    The isotopic and impurity content of 15 water triple-point cells, manufactured at NMi VSL in the past three years, were investigated.\\u000a The isotopic analyses were performed on water specimens sampled at three different stages of the manufacturing process. This\\u000a allowed us to separate and quantify the influence of the source water and of the manufacturing process (distillation, degassing)\\u000a on the

  20. A novel point-of-use water treatment method by antimicrobial nanosilver textile material.

    PubMed

    Liu, Hongjun; Tang, Xiaosheng; Liu, Qishan

    2014-12-01

    Pathogenic bacteria are one of the main reasons for worldwide water-borne disease causing a big threat to public health, hence there is an urgent need to develop cost-effective water treatment technologies. Nano-materials in point-of-use systems have recently attracted considerable research and commercial interests as they can overcome the drawbacks of traditional water treatment techniques. We have developed a new point-of-use water disinfection kit with nanosilver textile material. The silver nanoparticles were in-situ generated and immobilized onto cotton textile, followed by fixing to a plastic tube to make a water disinfection kit. By soaking and stirring the kit in water, pathogenic bacteria have been killed within minutes. The silver leaching from the kit was insignificant, with values <100 ppb - the current US EPA and WHO limit for silver level in drinking water. Herein, the nanosilver textile water disinfection kit could be a new, efficient and cost-effective point-of-use water treatment method for rural areas and emergency preparedness. PMID:25473975

  1. Costs and water quality effects of controlling point and nonpoint pollution sources

    SciTech Connect

    Macal, C.M.; Broomfield, B.J.

    1980-01-01

    Costs and water quality effects of controlling point and nonpoint pollution sources are compared for the DuPage River basin in northern Illinois. Costs are estimated for effluent standards for municipal wastewater treatment plants and for the alternative, controlling runoff from nonpoint sources such as streets, agricultural lands, and forests. A dynamic water-quality/hydrology simulation model is used to determine water quality effects of various treatment plant standards and nonpoint-source controls. Costs and water quality data are combined, and the point-source and nonpoint-source plans are compared on a cost-effectiveness basis. Nonpoint-source controls are found to be more cost-effective than stricter control of pollutants from point sources.

  2. Point-of-use water treatment and diarrhoea reduction in the emergency context: an effectiveness trial in Liberia

    E-print Network

    Scharfstein, Daniel

    Point-of-use water treatment and diarrhoea reduction in the emergency context: an effectiveness in current water treatment technologies, and few products are capable of treating turbid water. We describe the findings of a 12-week effectiveness study of point-of-use water treatment with a flocculant

  3. Fuel Cell Freeze Startup and Landscape of FC Freeze Patents

    E-print Network

    Patents · Top categories ­ Fuel cell stack (212) ­ Piping (104) ­ Solid electrolyte fuel cell (119Fuel Cell Freeze Startup and Landscape of FC Freeze Patents DOE Workshop on Fuel Cell Operations of PEM fuel cells from sub-freezing temperatures. Approach · Collect data/information through literature

  4. 40 CFR 141.100 - Criteria and procedures for public water systems using point-of-entry devices.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...false Criteria and procedures for public water systems using point-of-entry devices...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Use of Non-Centralized...

  5. 40 CFR 141.100 - Criteria and procedures for public water systems using point-of-entry devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...false Criteria and procedures for public water systems using point-of-entry devices...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Use of Non-Centralized...

  6. 40 CFR 141.100 - Criteria and procedures for public water systems using point-of-entry devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...false Criteria and procedures for public water systems using point-of-entry devices...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Use of Non-Centralized...

  7. 40 CFR 141.100 - Criteria and procedures for public water systems using point-of-entry devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...false Criteria and procedures for public water systems using point-of-entry devices...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Use of Non-Centralized...

  8. 40 CFR 141.100 - Criteria and procedures for public water systems using point-of-entry devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...false Criteria and procedures for public water systems using point-of-entry devices...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS Use of Non-Centralized...

  9. On the nature of pre-freeze mortality in insects: water balance, ion homeostasis and energy charge in the adults of Pyrrhocoris apterus

    Microsoft Academic Search

    V. Kostal; J. Vambera; J. Bastl

    2004-01-01

    Three acclimation groups (i.e. non-diapause (LD), diapause (SD) and diapause, cold-acclimated (SDA)) of the adult bugs Pyrrhocoris apterus differed markedly in their levels of chill tolerance. Survival time at a sub-zero, but non-freezing, temperature of -5°C (Lt50) extended from 7.6·days, through 35.6·days, to >60·days in the LD, SD and SDA insects, respectively. The time necessary for recovery after chill-coma increased

  10. Freezing Poultry for Home Use 

    E-print Network

    Davis, Michael

    2006-08-31

    Purchasing fresh poultry in large packages and freezing it in quantities suitable for individual meals can stretch time and food dollars. Topics include packaging needs, cutting, storing and thawing instructions, and freezing pre-cooked meals....

  11. Deliquesence and freezing of stratospheric aerosol observed by balloonborne backscattersondes

    SciTech Connect

    Larsen, N.; Knudsen, B. [Danish Meterological Institute, Copenhagen (Denmark)] [Danish Meterological Institute, Copenhagen (Denmark); Rosen, J.M. [Univ. of Wyoming, Laramie, WY (United States)] [and others] [Univ. of Wyoming, Laramie, WY (United States); and others

    1995-05-15

    Stratospheric sulfate aerosols, originating from the Mt. Pinatubo volcanic eruption, have been observed during three winters in the Arctic by balloonborne backscattersondes. A measured color index, defined as the quotient between the aerosol backscatter ratios at wavelengths 940 and 480 nm, provides information of the size of the observed particles. The effects of liquid particle growth, by water vapor uptake, clearly show up as changes in the color index, whereas measurements on other days indicate the particles to be frozen. Air parcel trajectories have been calculated, providing the temperature history of the observed particles. Evidences appear of a temperature hysteresis in the freezing and melting cycle of the aerosol, indicating melting temperatures around 215-220 K in good agreement with laboratory measurements, and freezing of the particles within less than 5 K above the ice frost point. The changes in color index of the liquid particles are in good agreement with predictions from theoretical model calculations of growth by water vapor uptake. 13 refs., 5 figs., 1 tab.

  12. Freezing and thawing processes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seasonally frozen soil strongly influences runoff and erosion on large areas of land around the world. In many areas, rain or snowmelt on seasonally frozen soil is the single leading cause of severe runoff and erosion events. As soils freeze, ice blocks the soil pores, greatly diminishing the perm...

  13. Animal Anti-Freeze

    NSDL National Science Digital Library

    2012-06-26

    In this outdoor winter activity, learners search for and create hibernation sites that will protect gelatin "animals" from freezing. Learners come to understand that hibernating animals need to take care in selecting a sleeping spot that will provide protection from the winter cold.

  14. Freezing of triangulations

    NASA Astrophysics Data System (ADS)

    Kownacki, J.-P.

    2004-04-01

    Zero temperature dynamics of two dimensional triangulations of a torus with curvature energy is described. Numerical simulations strongly suggest that the model get frozen in metastable states, made of topological defects on flat surfaces, that group into clusters of same topological charge. It is conjectured that freezing is related to high temperature structure of baby universes.

  15. Modeling soil freezing dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seasonally frozen soil strongly influences runoff and erosion on large areas of land around the world. In many areas, rain or snowmelt on seasonally frozen soil is the single leading cause of severe runoff and erosion events. As soils freeze, ice blocks the soil pores, greatly diminishing the permea...

  16. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture... Rooms and Compartments § 58.621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures...

  17. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture... Rooms and Compartments § 58.621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures...

  18. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture... Rooms and Compartments § 58.621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures...

  19. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture... Rooms and Compartments § 58.621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures...

  20. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture... Rooms and Compartments § 58.621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures...

  1. Freeze-drying of proteins.

    PubMed

    Liu, Baolin; Zhou, Xinli

    2015-01-01

    Freeze-drying has become one of the most important processes for the preservation of biological products. This chapter provides protocols for freeze-drying of proteins and discusses the importance of formulation, cycle development, and validation. Specific formulations for stabilization of proteins are presented as well as advice on common problems with freeze-drying of proteins. PMID:25428023

  2. A practical method of realizing the triple point of water using totally frozen cells

    Microsoft Academic Search

    M. Tischler

    1997-01-01

    A simple, economical and time-saving procedure is described for maintaining water triple point cells (WTPCs) ready for use for indefinite periods, based on storing the WTPCs totally frozen. The uncertainty of reproducibility of the triple point temperature does not exceed 0,1 mK.The WTPC is kept in direct contact with crushed ice in a Dewar flask. Under such conditions the natural

  3. Freeze plug proves safe, economical in riser repair

    SciTech Connect

    Nelson, M.J. [Exxon Co. U.S.A., New Orleans, LA (United States)

    1995-05-01

    In October 1992, Exxon Pipeline Co., Houston, performed in the Gulf of Mexico what the company believes to have been the first underwater freeze-plug procedure. To form a plug, water in a small section of the pipe is frozen with liquid nitrogen. In partially replacing a 10-in. riser at South Marsh Island Block 6A, Exxon Pipeline worked closely with a freeze-plug service company to minimize environmental and personnel exposure and to avoid the chance of an oil spill. The freeze plug reduced the time the pipe was open-ended during the repair, and hydrotesting the freeze plug area and repair section ensured integrity. The paper describes onshore testing of the procedures, pre-work surface cleaning, and the freeze-plug procedure.

  4. Microbial risk assessment with the OAEL approach at water abstraction points in rural Kenya

    Microsoft Academic Search

    Paul T. Yillia; Norbert Kreuzinger; Jude M. Mathooko; Ernest T. Ndomahina

    2009-01-01

    US-based models for recreational water quality were applied to characterize the potential health risk (PHR) of infection with gastroenteritis (GI) and highly credible gastroenteritis (HCGI) illnesses from single exposure at several water abstraction points (WAPs) along the Njoro River in rural Kenya. Ambient geometric mean densities of Escherichia coli (EC) and intestinal enterococci (IE) were generally high (2–4log units of

  5. Bacterial treatment effectiveness of point-of-use ceramic water filters

    Microsoft Academic Search

    Angela R. Bielefeldt; Kate Kowalski; R. Scott Summers

    2009-01-01

    Laboratory experiments were conducted on six point-of-use (POU) ceramic water filters that were manufactured in Nicaragua; two filters were used by families for ca. 4years and the other filters had limited prior use in our lab. Water spiked with ca. 106CFU\\/mL of Escherichia coli was dosed to the filters. Initial disinfection efficiencies ranged from 3 – 4.5log, but the treatment efficiency decreased with subsequent batches

  6. Improved Estimates of the Isotopic Correction Constants for the Triple Point of Water

    Microsoft Academic Search

    D. R. White; W. L. Tew

    2010-01-01

    In 2006, the CIPM clarified the definition of the kelvin by specifying the isotopic composition of the water to be used in\\u000a the realization of the triple point. At the same time, the Consultative Committee for Thermometry gave recommended values\\u000a for the isotopic correction constants to be used for water departing from the specified composition. However, the uncertainties\\u000a in the

  7. Isotopic Effects on the Temperature of the Triple Point of Water

    Microsoft Academic Search

    X. K. Yan; J. T. Zhang; Y. L. Wang; C. F. Ma; Y. N. Duan

    2008-01-01

    An investigation into the effects of isotopic composition on the triple point temperature of water has been carried out at\\u000a the National Institute of Metrology (NIM), China, since redefinition of the kelvin with respect to Vienna Standard Mean Ocean\\u000a Water (V-SMOW) was officially proposed by the Consultative Committee for Thermometry (CCT) in 2005. In this paper, a comparison\\u000a of four

  8. Automated Realization of the Triple Point of Water Using the Mush Method

    Microsoft Academic Search

    X. K. Yan; Y. N. Duan; J. H. Yang; J. Li

    2011-01-01

    In order to investigate mechanisms of phase transitions of supercooled water in a triple-point-of-water (TPW) cell when a\\u000a mush method was used to create an ice mantle, an automated apparatus using small TPW cells was developed to obtain the TPW.\\u000a In this article, the design principle, the apparatus, and the procedure for an automated formation of ice mantles in small

  9. Condensation and freezing of droplets on superhydrophobic surfaces.

    PubMed

    Oberli, Linda; Caruso, Dean; Hall, Colin; Fabretto, Manrico; Murphy, Peter J; Evans, Drew

    2014-08-01

    Superhydrophobic coatings are reported as promising candidates for anti-icing applications. Various studies have shown that as well as having ultra water repellency the surfaces have reduced ice adhesion and can delay water freezing. However, the structure or texture (roughness) of the superhydrophobic surface is subject to degradation during the thermocycling or wetting process. This degradation can impair the superhydrophobicity and the icephobicity of those coatings. In this review, a brief overview of the process of droplet freezing on superhydrophobic coatings is presented with respect to their potential in anti-icing applications. To support this discussion, new data is presented about the condensation of water onto physically decorated substrates, and the associated freezing process which impacts on the freezing of macroscopic droplets on the surface. PMID:24200089

  10. 33 CFR 149.575 - How must objects protruding from the water, other than platforms and single point moorings, be...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...from the water, other than platforms and single point moorings, be marked? 149.575...from the water, other than platforms and single point moorings, be marked? (a...that is within 100 yards of a platform or single point mooring (SPM) must be marked...

  11. 33 CFR 149.575 - How must objects protruding from the water, other than platforms and single point moorings, be...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...from the water, other than platforms and single point moorings, be marked? 149.575...from the water, other than platforms and single point moorings, be marked? (a...that is within 100 yards of a platform or single point mooring (SPM) must be marked...

  12. 33 CFR 149.575 - How must objects protruding from the water, other than platforms and single point moorings, be...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...from the water, other than platforms and single point moorings, be marked? 149.575...from the water, other than platforms and single point moorings, be marked? (a...that is within 100 yards of a platform or single point mooring (SPM) must be marked...

  13. 33 CFR 149.575 - How must objects protruding from the water, other than platforms and single point moorings, be...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...from the water, other than platforms and single point moorings, be marked? 149.575...from the water, other than platforms and single point moorings, be marked? (a...that is within 100 yards of a platform or single point mooring (SPM) must be marked...

  14. Evaluation and Validation of the Messinger Freezing Fraction

    NASA Technical Reports Server (NTRS)

    Anderson, David N.; Tsao, Jen-Ching

    2005-01-01

    One of the most important non-dimensional parameters used in ice-accretion modeling and scaling studies is the freezing fraction defined by the heat-balance analysis of Messinger. For fifty years this parameter has been used to indicate how rapidly freezing takes place when super-cooled water strikes a solid body. The value ranges from 0 (no freezing) to 1 (water freezes immediately on impact), and the magnitude has been shown to play a major role in determining the physical appearance of the accreted ice. Because of its importance to ice shape, this parameter and the physics underlying the expressions used to calculate it have been questioned from time to time. Until now, there has been no strong evidence either validating or casting doubt on the current expressions. This paper presents experimental measurements of the leading-edge thickness of a number of ice shapes for a variety of test conditions with nominal freezing fractions from 0.3 to 1.0. From these thickness measurements, experimental freezing fractions were calculated and compared with values found from the Messinger analysis as applied by Ruff. Within the experimental uncertainty of measuring the leading-edge thickness, agreement of the experimental and analytical freezing fraction was very good. It is also shown that values of analytical freezing fraction were entirely consistent with observed ice shapes at and near rime conditions: At an analytical freezing fraction of unity, experimental ice shapes displayed the classic rime shape, while for conditions producing analytical freezing fractions slightly lower than unity, glaze features started to appear.

  15. Freezing and Food Safety

    MedlinePLUS

    ... Administrative Forms Standard Forms Skip Navigation Z7_0Q0619C0JGR010IFST1G5B10H1 Web Content Viewer (JSR 286) Actions ${title} Loading... / Topics / ... Food Safety / Freezing and Food Safety Z7_0Q0619C0JGR010IFST1G5B10H3 Web Content Viewer (JSR 286) Actions ${title} Loading... Z7_ ...

  16. Second critical point of water in supercooled confined water in L,L-diphenylalanine micro/nanotubes

    E-print Network

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

    2014-06-26

    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.

  17. Effects of Electric and Magnetic Field on Freezing and Possible Relevance in Freeze Drying

    Microsoft Academic Search

    M. W. Woo; A. S. Mujumdar

    2010-01-01

    Application of an electric or magnetic field can significantly affect the freezing characteristics of water. A DC electric field will tend to induce ice nucleation at a lower degree of supercooling, and there is evidence to show that an AC electric field delays the onset of ice nucleation. Industrial research has shown that a magnetic field can be used to

  18. Is there a long-term drift in triple point of water cells?

    Microsoft Academic Search

    K D Hill

    2001-01-01

    A recent study identified boron, sodium, aluminium and silicon as the dominant impurities in triple point of water (TPW) cells. These results suggest that borosilicate glass is a less than ideal container as it is the most likely source of the contaminating elements. An estimate for the rate of change of the equilibrium temperature of TPW cells is presented using

  19. Measuring the residual air pressure in triple-point-of-water cells

    Microsoft Academic Search

    D R White

    2004-01-01

    Residual gas pressure is one of the factors influencing the temperature realized by triple-point-of-water cells. This note describes a simple procedure for measuring and correcting for the residual air pressure in sealed cells. The procedure is applicable to any cell with a McLeod-gauge extension or sufficient remnant ‘seal-off’ tube to trap an air bubble.

  20. DESIGN NOTE: Measuring the residual air pressure in triple-point-of-water cells

    Microsoft Academic Search

    D. R. White

    2004-01-01

    Residual gas pressure is one of the factors influencing the temperature realized by triple-point-of-water cells. This note describes a simple procedure for measuring and correcting for the residual air pressure in sealed cells. The procedure is applicable to any cell with a McLeod-gauge extension or sufficient remnant 'seal-off' tube to trap an air bubble.

  1. The Discontinuity in the First Derivative of the ITS90 at the Triple Point of Water

    Microsoft Academic Search

    R. L. Rusby

    2010-01-01

    This paper investigates the discontinuity in the derivative [d W\\/d T 90]TPW of the ITS-90 at the triple point of water, using data for over 40 calibrated standard platinum resistance thermometers (SPRTs). It finds that the discontinuity is in most cases somewhere between 0 and -6 parts in 105, in relative terms, but that the higher numerical values are obtained

  2. Linear Programming Analysis of a Water Supply System with Multiple Supply Points

    Microsoft Academic Search

    Ishwar Gupta; M. Zia Hassan; John Cook

    1972-01-01

    An optimum water distribution system is designed using linear programming. The proposed algorithm, developed by applying an analogy of electrical network theory, discusses a distribution system with multiple supply points in comparison to an earlier paper by Gupta where the distribution system was restricted to only one source. The electrical network analogy is fully explained and a case example with

  3. A point focusing collector for an integrated water/power complex

    NASA Technical Reports Server (NTRS)

    Zewen, H.; Schmidt, G.; Moustafa, S.

    1982-01-01

    The utilization potential of the point focusing parabolic dish is identified. Its main design parameters are summarized. Performance tests and the utilization of the collector as primary energy source in a food-water-power complex are described. Process heat, heat storage, heat transfer, and cogeneration are discussed.

  4. Plant responses, climate pivot points, and trade-offs in water-limited ecosystems

    USGS Publications Warehouse

    Munson, Seth M.

    2013-01-01

    Plant species in dryland ecosystems are limited by water availability and may be vulnerable to increases in aridity. Methods are needed to monitor and assess the rate of change in plant abundance and composition in relation to climate, understand the potential for degradation in dryland ecosystems, and forecast future changes in plant species assemblages. I employ nearly a century of vegetation monitoring data from three North American deserts to demonstrate an approach to determine plant species responses to climate and critical points over a range of climatic conditions at which plant species shift from increases to decreases in abundance (climate pivot points). I assess these metrics from a site to regional scale and highlight how these indicators of plant performance can be modified by the physical and biotic environment. For example, shrubs were more responsive to drought and high temperatures on shallow soils with limited capacity to store water and fine-textured soils with slow percolation rates, whereas perennial grasses were more responsive to precipitation in sparse shrublands than in relatively dense grasslands and shrublands, where competition for water is likely more intense. The responses and associated climate pivot points of plant species aligned with their lifespan and structural characteristics, and the relationship between responses and climate pivot points provides evidence of the trade-off between the capacity of a plant species to increase in abundance when water is available and its drought resistance.

  5. POINT-OF-USE TREATMENT OF DRINKING WATER IN SAN YSIDRO, NM

    EPA Science Inventory

    This study was conducted to determine whether point-of-use (POU) reverse osmosis (RO) units could satisfactorily function in lieu of central treatment to remove arsenic and fluoride from the drinking water supply of San Ysidro, NM. POU treatment was evaluated for removal efficien...

  6. Langevin Poisson-Boltzmann equation: point-like ions and water dipoles near a charged surface.

    PubMed

    Gongadze, Ekaterina; van Rienen, Ursula; Kralj-Igli?, Veronika; Igli?, Aleš

    2011-06-01

    Water ordering near a charged membrane surface is important for many biological processes such as binding of ligands to a membrane or transport of ions across it. In this work, the mean-field Poisson-Boltzmann theory for point-like ions, describing an electrolyte solution in contact with a planar charged surface, is modified by including the orientational ordering of water. Water molecules are considered as Langevin dipoles, while the number density of water is assumed to be constant everywhere in the electrolyte solution. It is shown that the dielectric permittivity of an electrolyte close to a charged surface is decreased due to the increased orientational ordering of water dipoles. The dielectric permittivity close to the charged surface is additionally decreased due to the finite size of ions and dipoles. PMID:21613667

  7. Effect of wettability on sessile drop freezing: when superhydrophobicity stimulates an extreme freezing delay.

    PubMed

    Boinovich, Ludmila; Emelyanenko, Alexandre M; Korolev, Vadim V; Pashinin, Andrei S

    2014-02-18

    An increasing number of studies directed at supercooling water droplets on surfaces with different wettabilities have appeared in recent years. This activity has been stimulated by the recognition that water supercooling phenomena can be effectively used to develop methods for protecting outdoor equipment and infrastructure elements against icing and snow accretion. In this article, we discuss the nucleation kinetics of supercooled sessile water droplets on hydrophilic, hydrophobic, and superhydrophobic surfaces under isothermal conditions at temperatures of -8, -10, and -15 °C and a saturated water vapor atmosphere. The statistics of nucleation events for the ensembles of freezing sessile droplets is completed by the detailed analysis of the contact angle temperature dependence and freezing of individual droplets in a saturated vapor atmosphere. We have demonstrated that the most essential freezing delay is characteristic of the superhydrophobic coating on aluminum, with the texture resistant to contact with ice and water. This delay can reach many hours at T = -8 °C and a few minutes at -23 °C. The observed behavior is analyzed on the basis of different nucleation mechanisms. The dissimilarity in the total nucleation rate, detected for two superhydrophobic substrates having the same apparent contact angle of the water drop but different resistivities of surface texture to the contact with water/ice, is associated with the contribution of heterogeneous nucleation on external centers located at the water droplet/air interface. PMID:24491217

  8. Contact freezing of supercooled cloud droplets on collision with mineral dust particles: effect of particle size

    NASA Astrophysics Data System (ADS)

    Hoffmann, Nadine; Duft, Denis; Kiselev, Alexei; Leisner, Thomas

    2013-04-01

    The contact freezing of supercooled cloud droplets is one of the potentially important and the least investigated heterogeneous mechanism of ice formation in the tropospheric clouds [1]. On the time scales of cloud lifetime the freezing of supercooled water droplets via contact mechanism may occur at higher temperature compared to the same IN immersed in the droplet. However, the laboratory experiments of contact freezing are very challenging due to the number of factors affecting the probability of ice formation. In our experiment we study single water droplets freely levitated in the laminar flow of mineral dust particles acting as the contact freezing nuclei. By repeating the freezing experiment sufficient number of times we are able to reproduce statistical freezing behavior of large ensembles of supercooled droplets and measure the average rate of freezing events. We show that the rate of freezing at given temperature is governed only by the rate of droplet -particle collision and by the properties of the contact ice nuclei. In this contribution we investigate the relationship between the freezing probability and the size of mineral dust particle (represented by illite) and show that their IN efficiency scales with the particle size. Based on this observation, we discuss the similarity between the freezing of supercooled water droplets in immersion and contact modes and possible mechanisms of apparent enhancement of the contact freezing efficiency. [1] - K.C. Young, The role of contact nucleation in ice phase initiation in clouds, Journal of the Atmospheric Sciences 31, 1974

  9. Freeze out of the expanding system

    E-print Network

    V. K. Magas; L. P. Csernai; E. Molnar

    2007-02-22

    The freeze out (FO) of the expanding systems, created in relativistic heavy ion collisions, is discussed. We start with kinetic FO model, which realizes complete physical FO in a layer of given thickness, and then combine our gradual FO equations with Bjorken type system expansion into a unified model. We shall see that the basic FO features, pointed out in the earlier works, are not smeared out by the expansion.

  10. Freeze Crystallization Processes: Efficiency by Flexibility 

    E-print Network

    Heist, J. A.; Barron, T. S.

    1983-01-01

    and aromatics have very close bOlllng pOlnts, so fractional distillation is not practical. Extraction with tetramethylene sulfone or tetraethylene glycol (TeEG) is the usual method used to separate the aromatics from the parafins. The aromatics...-20, 1983 ~ CRUDE BTX [25 WTY. DE-PARIFFINED @ EXTRACT [60 WTY. TETRAETHYLENE GLYCOL) EUTECTIC POINT 230 240 220 210 0 x: W t 200 190 180 (CONVENTIONAL REFINING) ? ? ? FIGURE 6 8TX FREEZE REFINING The first of these is illustrated...

  11. High pressure freezing and thawing of foods: a review

    Microsoft Academic Search

    A LeBail; D Chevalier; D. M Mussa; M Ghoul

    2002-01-01

    The phase diagram of water shows that the melting temperature of water decreases with pressure down to ?21°C at 210 MPa while the opposite effect is observed above this pressure. This phenomenon allows the achievement of rapid freezing and thawing of foods that mainly contain water. In addition, pressure-assisted thawing has the advantage of inducing a reduction in drip loss

  12. Shaft Excavation in Frozen Ground at Point 5

    E-print Network

    Osborne, J

    2000-01-01

    Construction work on the 112 MCHF civil engineering contract started at Point 5 in August 1998. The new surface buildings and underground structures are necessary to accommodate the CMS detector for the LHC Project. The principal underground works consist of two new shafts, two parallel caverns separated by a supporting pillar, and a number of small connection tunnels and service galleries. The two shafts are to be sunk through approximately 50 m of water-bearing moraine to the underlying molasse rock. From a number of possible construction methods, ground freezing of the moraine was considered to be most appropriate. The ground freezing is used to control the groundwater and to support temporarily the moraine during excavation and lining of the shafts. The aim of this paper is to present the ground-freezing technique and to discuss the advantages and disadvantages of the system in the light of its first few months of running on the Point 5 site.

  13. Evaluation of Point of Use Water Treatment Devices for Removal of Mine Wastes from Well Water

    EPA Science Inventory

    U.S. EPA Region VII and the Office of Research and Development (ORD) are conducting a large-scale study to identify the prevalence of lead (Pb) and other contaminants in drinking water at four mine waste areas in Washington County, Missouri. Numerous households in Potosi, Richwoo...

  14. The ammonia freeze explosion (AFEX) process

    Microsoft Academic Search

    Mark T. Holtzapple; Jae-Hoon Jun; Ganesh Ashok; Srinivas L. Patibandla; Bruce E. Dale

    1991-01-01

    The Ammonia Freeze Explosion (AFEX) process treats lignocellulose with high-pressure liquid ammonia, and then explosively\\u000a releases the pressure. The combined chemical effect (cellulose decrystallization) and physical effect (increased accessible\\u000a surface area) dramatically increase lignocellulose susceptibility to enzymatic attack. There are many adjustable parameters\\u000a in the AFEX process: ammonia loading, water loading, temperature, time, blowdown pressure, and number of treatments. The

  15. Studies on Freezing RAM Semen in Absence of Glycerol.

    NASA Astrophysics Data System (ADS)

    Abdelnaby, Abdelhady Abdelhakeam

    1988-12-01

    Glycerol is widely used as a major cryoprotective agent for freezing spermatozoa of almost all species. However, it reduces fertility of sheep inseminated cervically compared with intrauterine insemination. Studies were conducted to develop a method and procedure for freezing ram semen in the absence of glycerol. Post -thaw survival of ram spermatozoa frozen in the absence of glycerol was affected by time and temperature after collection and before dilution and time after dilution and before freezing. Increase in time at 5^ circC before or after dilution and before freezing increased both post-thaw motility and number of cells passing through Sephadex filter. A cold dilution method was developed. Slow cooling of fresh ram semen and diluting at 5^circ C 2-3 hr. after collection, then freezing 1 hr. after dilution improved both post-thaw motility and number of cells passing through Sephadex filter compared with immediate dilution at 30-37^circC after collection and freezing 3-4 hr. later (P < 0.05). An extender was developed to freeze ram semen in the absence of glycerol. An increase in post-thaw motility was obtained when semen was extended in TES titrated with Tris to pH 7.0 (TEST) and osmotic pressure of 375-400 mOsm/kg, containing 25-30% (v/v) egg yolk and 10% (v/v) maltose. A special device (boat) for freezing was constructed to insure the same height of the sample above LN _2 and thus the same freezing rate from freeze to freeze. Freezing of semen in 0.25cc straws at 5-10 cm above LN_2 (73.8 to 49.5 ^circC/min) yielded higher post-thaw motility than the rates resulted from freezing at 15 cm above LN_2 or 1 cm above LN _2. Faster Thawing in 37^ circC water for 30 sec. (7.8^ circC/sec.) increased post-thaw motility compared with slower thawing in 5 or 20^circ C water (P < 0.05). A lambing rate of 52.2% was obtained in one fertility trial conducted with ram semen frozen without glycerol and 17.1% in a second trial. One injection (IM) of 15 mg PGF_{2alpha}/ewe for estrus synchronization during breeding season resulted in higher heat response and lambing rate than two injections given 10 days apart.

  16. Freeze Branding Horses 

    E-print Network

    Householder, Doug; Webb, Gary; Wigington, Sam; Bruemmer, Jason

    2001-06-29

    (like a clear straw) from the GF. On colored horses, pigment (black, brown, red, yellow, etc.) is added from the CF below the skin to the clear hairshaft, which gives the hair its color. When the intensely cold iron used in freeze branding is placed... site contains no pigment and appears white. This is the desired result?a uniform, white brand. If the iron is pressed to the skin for a shorter period of time and/or with less pressure than required, some hairs grow in colored and some hairs grow...

  17. Freeze Branding Horses

    E-print Network

    Householder, Doug; Webb, Gary; Wigington, Sam; Bruemmer, Jason

    2001-06-29

    , simpli- f_ied drawing of one hair shaft with its color (pigment) producing follicle (CF) and its growth follicle (GF), both shown below the skin. Doug Householder 1 , Gary Webb 2 , Sam Wigington 3 and Jason Bruemmer 4 Freeze Branding Horses Figure 1. Hair... manager, Horse Center, Department of Animal Science, Texas A&M University. Texas AgriLife Extension Service ? Zerle L. Carpenter, Director ? The Texas A&M University System ? College Station, Texas Under normal circumstances hair grows as a clear shaft...

  18. Supercooling and Freezing of HNO3\\/H2O Aerosols

    Microsoft Academic Search

    Dustin Dickens

    2000-01-01

    Abstract The freezing kinetics of binary nitric acid\\/water aerosols is of fundamental,importance to the modelling of polar stratospheric clouds and the role they in ozone depletion over the Arctic\\/Antarcticregions. Cirrus clouds are also often composed of nitric acid solutions, hence an understandingof freezing process in these aerosols also aids in modelling the earth’s radiation budget and global warming. This thesis

  19. Boiling water with ice: Effect of pressure on the boiling point of water

    NSDL National Science Digital Library

    This guided inquiry activity, in which ice is used to boil water in a Florence flask, works well in the introductory class to a chemistry or physical science course. The students will learn the difference between observation and inference and apply this understanding to various other situations in which observations and inferences must be made. The students will also use outside sources to try to explain why the activity worked.

  20. Monitoring coastal marine waters for spore-forming bacteria of faecal and soil origin to determine point from non-point source pollution.

    PubMed

    Fujioka, R S

    2001-01-01

    The US Environmental Protection Agency (USEPA) and the World Health Organization (WHO) have established recreational water quality standards limiting the concentrations of faecal indicator bacteria (faecal coliform, E. coli, enterococci) to ensure that these waters are safe for swimming. In the application of these hygienic water quality standards, it is assumed that there are no significant environmental sources of these faecal indicator bacteria which are unrelated to direct faecal contamination. However, we previously reported that these faecal indicator bacteria are able to grow in the soil environment of humid tropical island environments such as Hawaii and Guam and are transported at high concentrations into streams and storm drains by rain. Thus, streams and storm drains in Hawaii contain consistently high concentrations of faecal indicator bacteria which routinely exceed the EPA and WHO recreational water quality standards. Since, streams and storm drains eventually flow out to coastal marine waters, we hypothesize that all the coastal beaches which receive run-off from streams and storm drains will contain elevated concentrations of faecal indicator bacteria. To test this hypothesis, we monitored the coastal waters at four beaches known to receive water from stream or storm drains for salinity, turbidity, and used the two faecal indicator bacteria (E. coli, enterococci) to establish recreational water quality standards. To determine if these coastal waters are contaminated with non-point source pollution (streams) or with point source pollution (sewage effluent), these same water samples were also assayed for spore-forming bacteria of faecal origin (Cl. perfringens) and of soil origin (Bacillus species). Using this monitoring strategy it was possible to determine when coastal marine waters were contaminated with non-point source pollution and when coastal waters were contaminated with point source pollution. The results of this study are most likely applicable to all countries in the warm and humid region of the world. PMID:11724486

  1. On the particle paths and the stagnation points in small-amplitude deep-water waves

    E-print Network

    Delia Ionescu-Kruse

    2012-02-22

    In order to obtain quite precise information about the shape of the particle paths below small-amplitude gravity waves travelling on irrotational deep water, analytic solutions of the nonlinear differential equation system describing the particle motion are provided. All these solutions are not closed curves. Some particle trajectories are peakon-like, others can be expressed with the aid of the Jacobi elliptic functions or with the aid of the hyperelliptic functions. Remarks on the stagnation points of the small-amplitude irrotational deep-water waves are also made.

  2. Effects of freezing on plant mesophyll cells.

    PubMed

    Krause, G H; Grafflage, S; Rumich-Bayer, S; Somersalo, S

    1988-01-01

    Freezing and thawing of leaves of herbaceous plants leads to damage when the freezing temperature falls below a certain tolerance limit, which depends on the plant species and state of acclimation. Such damage is expressed as an irreversible inhibition of photosynthesis observed after thawing. In frost-damaged leaves the capacity of photosynthetic reactions of the thylakoid membranes is impaired. Particularly, the water-oxidation system, photosystems II and I are inhibited. However, it appears that CO2 assimilation is more readily affected by freezing stress than the activity of the thylakoids. The inhibition of CO2 fixation seen in initial stages of damage seems to be independent of thylakoid inactivation. This can be shown by chlorophyll fluorescence analysis made simultaneously with measurement of CO2 assimilation. Fluorescence emission by leaves is strongly influenced by carbon assimilation activity, namely via the redox state of the photosystem II electron acceptor QA (QA-dependent quenching) and via energization of the thylakoid membranes depending on the transthylakoid proton gradient (energy-dependent quenching). Resolution of these components of fluorescence changes provides insight into alterations of the CO2 fixing capacity of the chloroplasts and properties of the thylakoids. The effects of freezing and thawing were studied in detail with isolated mesophyll protoplasts prepared from both non-hardened and cold-acclimated plants of Valerianella locusta L. Freezing damage was characterized by various parameters such as plasma membrane integrity, photosynthetic CO2 assimilation, chlorophyll fluorescence emission and activities of thylakoids isolated from the protoplasts. All tests indicated a substantially increased frost tolerance of protoplasts obtained from cold-acclimated as compared to non-hardened leaves. CO2 assimilation and related fluorescence changes were the most freezing-sensitive parameters in both types of protoplasts. Inactivation of CO2 assimilation was correlated neither to the disintegration of the plasma membrane nor to inactivation of the thylakoids. Experimental data indicate that freeze-thaw treatment affected the light-regulated enzymes of the carbon reduction cycle, such as fructose-1,6-bisphosphatase, sedoheptulose-1,7-bisphosphatase and ribulose-1,5-bisphosphate carboxylase. Inhibition of light-activation of these enzymes may be based on altered properties of the chloroplast envelope. PMID:3077862

  3. Screening and identification of early warning algal species for metal contamination in fresh water bodies polluted from point and non-point sources.

    PubMed

    Rai, U N; Dubey, Smita; Shukla, O P; Dwivedi, S; Tripathi, R D

    2008-09-01

    The water bodies of Lucknow, Unnao and Kanpur (U.P.), India polluted through various point and non point sources were found to be either eutrophic or oligotrophic in nature. These water bodies supported a great number of algal diversity, which varied seasonally depending upon the physico-chemical properties of water. Further, the water bodies polluted through non point sources supports diverse algal species, while the water bodies polluted through point sources supports growth of tolerant blue green algae. High biomass producing algal species growing in these water bodies have accumulated significant amount of metals in their tissues. Maximum amount of Fe was found accumulated by species of Oedogonium sp. II (20,523.00 microg g(-1) dw) and Spirogyra sp. I (4,520.00 microg g(-1) dw), while maximum Chromium (Cr) was found accumulated in Phormedium bohneri (2,109.00 microg g(-1) dw) followed by Oscillatoria nigra (1,957.88 microg g(-1) dw) and Oedogonium sp. I (156.00 microg g(-1) dw) and Ni in Ulothrix sp. (495.00 microg g(-1) dw). Results showed that some of these forms growing in polluted environment and accumulating high amounts of toxic metals may be used as bioindicator species, however, their performance in metal contaminated water under different ecological niche is to be ascertained. PMID:18071919

  4. Final report on EURAMET.TK7.2: Bilateral comparison of water triple point cells

    Microsoft Academic Search

    A Peruzzi; A Szmyrka Grzebyk

    2012-01-01

    This is the final report of EURAMET.T-K7.2 bilateral comparison of water triple point cells. This comparison was requested by the Institute of Low Temperature and Structure Research, INTiBS, in its role as designated institute of Poland for participation in the CIPM MRA in the low temperature range of the thermometry field. The measurement protocol adopted was compatible with EURAMET.T-K7 with

  5. The Discontinuity in the First Derivative of the ITS90 at the Triple Point of Water

    Microsoft Academic Search

    R. L. Rusby

    2010-01-01

    This paper investigates the discontinuity in the derivative [dW\\/dT\\u000a 90]TPW of the ITS-90 at the triple point of water, using data for over 40 calibrated standard platinum resistance thermometers (SPRTs).\\u000a It finds that the discontinuity is in most cases somewhere between 0 and ?6 parts in 105, in relative terms, but that the higher numerical values are obtained for ‘less ideal’

  6. Comparison of Point-of-Use Technologies for Emergency Disinfection of Sewage-Contaminated Drinking Water ?

    PubMed Central

    McLennan, S. Devin; Peterson, Lauren A.; Rose, Joan B.

    2009-01-01

    Four point-of-use disinfection technologies for treating sewage-contaminated well water were compared. Three systems, based on flocculant-disinfectant packets and N-halamine chlorine and bromine contact disinfectants, provided a range of 4.0 to >6.6 log10 reductions (LR) of naturally occurring fecal indicator and heterotrophic bacteria and a range of 0.9 to >1.9 LR of coliphage. PMID:19767479

  7. Calculation of photon energy deposition kernels and electron dose point kernels in water

    Microsoft Academic Search

    Ernesto Mainegra-Hing; D. W. O. Rogers; Iwan Kawrakow

    2005-01-01

    Eects of changes in the physics of EGSnrc compared to EGS4\\/PRESTA on energy deposition kernels for monoenergetic photons and on dose point kernels for beta sources in water are investigated. In the diagnostic energy range, Compton binding corrections were found to increase the primary energy fraction up to 4.5% at 30 keV with a corresponding reduction of the scatter component

  8. Swash-aquifer interaction in the vicinity of the water table exit point on a sandy beach

    Microsoft Academic Search

    Nick Cartwright; Tom E. Baldock; Peter Nielsen; Dong-Sheng Jeng; Longbin Tao

    2006-01-01

    The coupling of sandy beach aquifers with the swash zone in the vicinity of the water table exit point is investigated through simultaneous measurements of the instantaneous shoreline (swash front) location, pore pressures and the water table exit point. The field observations reveal new insights into swash-aquifer coupling not previously gleaned from measurements of pore pressure only. In particular, for

  9. Figure indicates onset of freeze-thaw cycles with 1st day being 1st October

    E-print Network

    Cherkauer, Keith

    September of the water year. Why Soil Frost Is Important ? Hydrologic Time Series Analysis Of Climatic. · To perform hydrologic time series analysis to test for the presence of significant trends in soil freezing Inconsistency Check Missing Dates and Data Identified Data Processing based on Water Year Freeze-Thaw Cycles

  10. Assessment of ground-water contamination in the alluvial aquifer near West Point, Kentucky

    USGS Publications Warehouse

    Lyverse, M.A.; Unthank, M.D.

    1988-01-01

    Well inventories, water level measurements, groundwater quality samples, surface geophysical techniques (specifically, electromagnetic techniques), and test drilling were used to investigate the extent and sources of groundwater contamination in the alluvial aquifer near West Point, Kentucky. This aquifer serves as the principal source of drinking water for over 50,000 people. Groundwater flow in the alluvial aquifer is generally unconfined and moves in a northerly direction toward the Ohio River. Two large public supply well fields and numerous domestic wells are located in this natural flow path. High concentrations of chloride in groundwater have resulted in the abandonment of several public supply wells in the West Point areas. Chloride concentrations in water samples collected for this study were as high as 11,000 mg/L. Electromagnetic techniques indicated and test drilling later confirmed that the source of chloride in well waters was probably improperly plugged or unplugged, abandoned oil and gas exploration wells. The potential for chloride contamination of wells exists in the study area and is related to proximity to improperly abandoned oil and gas exploration wells and to gradients established by drawdowns associated with pumped wells. Periodic use of surface geophysical methods, in combination with added observation wells , could be used to monitor significant changes in groundwater quality related to chloride contamination. (USGS)

  11. Evaluating the sustainability of ceramic filters for point-of-use drinking water treatment.

    PubMed

    Ren, Dianjun; Colosi, Lisa M; Smith, James A

    2013-10-01

    This study evaluates the social, economic, and environmental sustainability of ceramic filters impregnated with silver nanoparticles for point-of-use (POU) drinking water treatment in developing countries. The functional unit for this analysis was the amount of water consumed by a typical household over ten years (37,960 L), as delivered by either the POU technology or a centralized water treatment and distribution system. Results indicate that the ceramic filters are 3-6 times more cost-effective than the centralized water system for reduction of waterborne diarrheal illness among the general population and children under five. The ceramic filters also exhibit better environmental performance for four of five evaluated life cycle impacts: energy use, water use, global warming potential, and particulate matter emissions (PM10). For smog formation potential, the centralized system is preferable to the ceramic filter POU technology. This convergence of social, economic, and environmental criteria offers clear indication that the ceramic filter POU technology is a more sustainable choice for drinking water treatment in developing countries than the centralized treatment systems that have been widely adopted in industrialized countries. PMID:23991752

  12. Two-point Dixon technique for water-fat signal decomposition with B0 inhomogeneity correction.

    PubMed

    Coombs, B D; Szumowski, J; Coshow, W

    1997-12-01

    To separate water and lipid resonance signals by phase-sensitive MRI, a two-point Dixon (2PD) reconstruction is presented in which phase-unwrapping is used to obtain an inhomogeneity map based on only in-phase and out-of-phase image data. Two relaxation-weighted images, a "water image" and a "fat image," representing a two-resonance peak model of proton density, are output. The method is designed for T1- or density-weighted spin-echo imaging; a double-echo scheme is more appropriate for T2-weighted spin-echo imaging. The technique is more time-efficient for clinical fat-water imaging than 3PD schemes, while still correcting for field inhomogeneity. PMID:9402188

  13. Extrinsic nature of point defects on the Si(001) surface: dissociated water molecules.

    PubMed

    Yu, Sang-Yong; Kim, Hanchul; Koo, Ja-Yong

    2008-01-25

    Point defects on a Si(001)-(2 x 1) surface were examined by scanning tunneling microscopy and ab initio pseudopotential calculations. The residual water molecules in the ultrahigh vacuum chamber are found to be the sole origin of the type-C defects. Most of the apparent dimer vacancies in the filled-state images were found to show a distinct U-shaped triple-dimer footprint in the empty-state images, which also originate from water adsorption. These two defects were identified as a single dissociated water molecule forming Si-OH and Si-H bonds in the interdimer (type-C defect) and the on-dimer (dimer-vacancy-like or U-shape defect) configurations. PMID:18233010

  14. Freezing of barley studied by infrared video thermography.

    PubMed

    Pearce, R S; Fuller, M P

    2001-01-01

    Freezing of barley (Hordeum vulgare), Hordeum murinum, and Holcus lanatus was studied using infrared video thermography. In the field, ice could enter H. lanatus leaves through hydathodes. In laboratory tests with barley, initially 0.4% of the leaf water froze, spreading in alternate strips of high and low freezing intensity longitudinally at 1 to 4 cm s(-1), and simultaneously spreading laterally at 0.3 cm s(-1). Similar results were obtained in the field with H. lanatus. A distinct second, more intense, freezing event spread slowly from the margins of the leaves toward the midrib. Organs of uprooted barley tested in the laboratory froze in this order: nucleated leaf, roots, older leaves, younger leaves, and secondary tillers. When ice spread from one leaf to the rest of the plant the crown delayed spread to the roots and other leaves. There was a longer delay above than below -2 degrees C, helping to protect the crown from freezing during mild frosts. Initial spread of freezing was not damaging. However, the initial spread is a prerequisite for the second freezing event, which can cause damage. The route of the initial spread of ice may be extracellular, drawing water from more gel-like parts of the cell wall. PMID:11154332

  15. Polarizable six-point water models from computational and empirical optimization.

    PubMed

    Tröster, Philipp; Lorenzen, Konstantin; Tavan, Paul

    2014-02-13

    Tröster et al. (J. Phys. Chem B 2013, 117, 9486-9500) recently suggested a mixed computational and empirical approach to the optimization of polarizable molecular mechanics (PMM) water models. In the empirical part the parameters of Buckingham potentials are optimized by PMM molecular dynamics (MD) simulations. The computational part applies hybrid calculations, which combine the quantum mechanical description of a H2O molecule by density functional theory (DFT) with a PMM model of its liquid phase environment generated by MD. While the static dipole moments and polarizabilities of the PMM water models are fixed at the experimental gas phase values, the DFT/PMM calculations are employed to optimize the remaining electrostatic properties. These properties cover the width of a Gaussian inducible dipole positioned at the oxygen and the locations of massless negative charge points within the molecule (the positive charges are attached to the hydrogens). The authors considered the cases of one and two negative charges rendering the PMM four- and five-point models TL4P and TL5P. Here we extend their approach to three negative charges, thus suggesting the PMM six-point model TL6P. As compared to the predecessors and to other PMM models, which also exhibit partial charges at fixed positions, TL6P turned out to predict all studied properties of liquid water at p0 = 1 bar and T0 = 300 K with a remarkable accuracy. These properties cover, for instance, the diffusion constant, viscosity, isobaric heat capacity, isothermal compressibility, dielectric constant, density, and the isobaric thermal expansion coefficient. This success concurrently provides a microscopic physical explanation of corresponding shortcomings of previous models. It uniquely assigns the failures of previous models to substantial inaccuracies in the description of the higher electrostatic multipole moments of liquid phase water molecules. Resulting favorable properties concerning the transferability to other temperatures and conditions like the melting of ice are also discussed. PMID:24437570

  16. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection from the cold temperatures. The sinkholes destroyed homes, roads and se...

  17. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    The entire root perimeter of this tree collapsed in response to subsidence activity. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for pr...

  18. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    Sinkholes damage roadways and require constant maintenance for road safety. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for protection ...

  19. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    A sinkhole formed in a roadway caused traffic to detour around it while it is filled in, stabilized and repaved. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to...

  20. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    Sinkholes affect roadway safety and require constant maintenance and monitoring. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pumped water to irrigate their plants for p...

  1. Preparation of soil specimens for SEM analysis using freeze-cut-drying

    Microsoft Academic Search

    B. Shi; Z. Wu; H. Inyang; J. Chen; B. Wang

    1999-01-01

    A new method, freeze-cut-drying, is introduced for preparing a soil specimen for microstructural analysis using scanning\\u000a electron microscopy (SEM). With this method, moisture in the specimen is removed by freeze-drying and an SEM observation surface\\u000a is made by cutting the specimen at a temperature below freezing point. Tests on bentonite clay were used to compare the results\\u000a from this method

  2. Thermal freeze-out versus chemical freeze-out reexamined

    E-print Network

    Dariusz Prorok

    2010-03-04

    An alternative, to the commonly used blast-wave, model describing the freeze-out hypersurface is applied to fit the $p_{T}$-spectra of identified hadrons measured at relativistic heavy-ion collisions at $\\sqrt{s_{NN}}=62.4, 130$ and 200 GeV. Decays of resonances are taken into account completely. It has turned out that the fitted freeze-out temperature and baryon number chemical potential depend weakly on the centrality of the collision and their values are close to the chemical freeze-out values determined from fits to particle yield ratios.

  3. Diarrhoea prevention in Bolivia through point-of-use water treatment and safe storage: a promising new strategy

    Microsoft Academic Search

    R. E. QUICK; L. V. VENCZEL; E. D. MINTZ; L. SOLETO; J. APARICIO; M. GIRONAZ; L. HUTWAGNER; K. GREENE; C. BOPP; K. MALONEY; D. CHAVEZ; M. SOBSEY; R. V. TAUXE

    1999-01-01

    SUMMARY A novel water quality intervention that consists of point-of-use water disinfection, safe storage and community education was field tested in Bolivia. A total of 127 households in two periurban communities were randomized into intervention and control groups, surveyed and the intervention was distributed. Monthly water quality testing and weekly diarrhoea surveillance were conducted. Over a 5-month period, intervention households

  4. Math 315 Exam #3 Solutions in Brief 1. (20 points) Two tanks contain 10 liters of water each. Initially tank

    E-print Network

    Math 315 Exam #3 Solutions in Brief 1. (20 points) Two tanks contain 10 liters of water each. Initially tank 1 contains no salt and tank 2 contains 246 grams of salt. Water con- taining 50 grams of salt per liter is added to tank 1 at the rate 2 liters/minute. Water containing no salt is added to tank 2

  5. Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.

    PubMed

    Horn, Hans W; Swope, William C; Pitera, Jed W

    2005-11-15

    The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water. PMID:16321097

  6. Assessing Impurities in Triple-Point-of-Water Cells Using a Capacitance Conductivity Test

    NASA Astrophysics Data System (ADS)

    Yan, X. K.; White, D. R.; Hao, X. M.; Yu, Z. J.; Edgar, H.; Duan, Y. N.

    2015-03-01

    Chemical analysis of old triple-point-of-water (TPW) cells has shown that the dominant impurities in the water are the principal constituents of borosilicate glass, which suggests the long-term downward drift observed in the realized triple-point temperature of TPW cells is caused by gradual dissolution of the glass containers. Because some of the glass constituents contribute to the electrical conductivity of the water, measurement of the conductivity provides a possible means for monitoring the long-term drift of TPW cells. This paper investigates the utility of a conductivity measurement, based on the measurement of a capacitor using the TPW cell as a dielectric, as a non-destructive means for monitoring the long-term stability of cells. The measurement exploits the cylindrical geometry of the cell and uses a two-terminal-pair coaxial electrical definition of capacitance. The results include estimates of the sensitivity of the method and examples of the long-term behavior of TPW cells, some as old as 38 years and monitored for periods of up to 10 years. It is found that the conductivity measurements correlate well with the cell age, with the drift rates increasing with time, as expected from the chemical model of glass dissolution. Measurements of temperature differences between cells show the technique can detect changes as small as , and therefore the method is a useful means of monitoring TPW cells.

  7. State diagrams of freeze-dried camu-camu ( Myrciaria dubia (HBK) Mc Vaugh) pulp with and without maltodextrin addition

    Microsoft Academic Search

    M. A. Silva; P. J. A. Sobral; T. G. Kieckbusch

    2006-01-01

    The state diagram for freeze-dried natural camu-camu pulp and for pulp with 30% maltodextrin DE 20 were determined by differential scanning calorimetry (DSC). Freeze-dried samples were equilibrated at 25°C over saturated salt solutions in order to achieve water activities between 0.11 and 0.90. Higher water activities were obtained by direct water addition on the freeze-dried product. Gordon–Taylor model was able

  8. Windchill and the risk of tissue freezing.

    PubMed

    Danielsson, U

    1996-12-01

    Low air temperatures and high wind speeds are associated with an increased risk of freezing of the exposed skin. P. A. Siple and C. F. Passel (Proc. Am. Phil. Soc. 89: 177-199, 1945) derived their windchill index from cooling experiments on a water-filled cylinder to quantify the risk of frostbite. Their results are reexamined here. It is found that their windchill index does not correctly describe the convective heat transfer coefficient (hc) for such a cylinder, the effect of the airspeed (v) is underestimated. New risk curves have been developed, based on the convection equations valid for cylinders in a cross flow, hc infinity v0.62, and tissue freezing data from the literature. An analysis of the data reveals a linear relationship between the frequency of finger frostbite and the surface temperature. This relation closely follows a normal distribution of finger-freezing temperatures, with an SD of 1 degree C. As the skin surface temperature falls from -4.8 to -7.8 degrees C, the risk of frostbite increases from 5 to 95%. These data indicate that the risk of finger frostbite is minor above an air temperature of -10 degrees C, irrespective of v, but below -25 degrees C there is a pronounced risk, even at low v. PMID:9018520

  9. A novel bottom-up process to produce drug nanocrystals: controlled crystallization during freeze-drying.

    PubMed

    de Waard, H; Hinrichs, W L J; Frijlink, H W

    2008-06-01

    To improve the dissolution behavior of lipophilic drugs, a novel bottom-up process based upon freeze drying which allows for the production of nanocrystalline particles was developed: "controlled crystallization during freeze drying". This novel process could strongly increase the dissolution behavior of fenofibrate. For example at a drug load of 30% w/w, 80% of the drug dissolved within 10 min from tablets prepared from the controlled crystallized dispersions, while from tablets prepared from the physical mixture only 50% was dissolved after 120 min. Furthermore it was found that faster freezing or using a solution with a lower water/tertiary butyl alcohol (TBA) ratio resulted in faster dissolution, indicating that the crystalline dispersions contained smaller crystals. Crystallization of the drug could occur during freezing or during drying. When crystallization occurs during freezing, faster freezing or using solutions with a lower water/TBA ratio results in the formation of more nuclei and consequently smaller crystals. When crystallization occurs during drying, faster freezing or using solutions with a higher water/TBA ratio results in the formation of smaller solvent crystals and therefore smaller interstitial spaces which contain the freeze-concentrated fraction. Since crystallization occurs in the freeze-concentrated fraction and the size of the crystals are limited to the size of the interstitial spaces, smaller crystals are formed in these situations. PMID:18423767

  10. Alcohol Brine Freezing of Japanese Horse Mackerel (Trachurus japonicus) for Raw Consumption

    NASA Astrophysics Data System (ADS)

    Maeda, Toshimichi; Yuki, Atsuhiko; Sakurai, Hiroshi; Watanabe, Koichiro; Itoh, Nobuo; Inui, Etsuro; Seike, Kazunori; Mizukami, Yoichi; Fukuda, Yutaka; Harada, Kazuki

    In order to test the possible application of alcohol brine freezing to Japanese horse mackerel (Trachurus japonicus) for raw consumption, the quality and taste of fish frozen by direct immersion in 60% ethanol brine at -20, -25 and -30°C was compared with those by air freezing and fresh fish without freezing. Cracks were not found during the freezing. Smell of ethanol did not remain. K value, an indicator of freshness, of fish frozen in alcohol brine was less than 8.3%, which was at the same level as those by air freezing and fresh fish. Oxidation of lipid was at the same level as air freezing does, and lower than that of fresh fish. The pH of fish frozen in alcohol brine at -25 and -30°C was 6.5 and 6.6, respectively, which were higher than that by air freezing and that of fresh fish. Fish frozen in alcohol brine was better than that by air and at the same level as fresh fish in total evaluation of sensory tests. These results show that the alcohol brine freezing is superior to air freezing, and fish frozen in alcohol brine can be a material for raw consumption. The methods of thawing in tap water, cold water, refrigerator, and at room temperature were compared. Thawing in tap water is considered to be convenient due to the short thaw time and the quality of thawed fish that was best among the methods.

  11. Effects of different methods of preparation of ice mantles of triple point of water cells on the temporal behaviour of the triple-point temperatures

    Microsoft Academic Search

    G T Furukawa; B W Mangum; G F Strouse

    1997-01-01

    We report results of an investigation of the temporal variation of the temperature of triple point of water (TPW) cells, in which the ice mantles were prepared by four different techniques using: (i) solid CO2, (ii) an immersion cooler, (iii) liquid-nitrogen-cooled rods, and (iv) liquid nitrogen (LN), first passing cold nitrogen vapours and then LN directly into the wells of

  12. Commercial Application of Freeze Crystallization 

    E-print Network

    Gorgol, R. G.

    1992-01-01

    crystallization, low temperature operation, separation of organic and in-organic contaminants, can be put to use. Freeze crystallization can be applied both economically and practically for specific wastewater applications....

  13. Review: freeze concentration technology applied to dairy products.

    PubMed

    Sánchez, J; Hernández, E; Auleda, J M; Raventós, M

    2011-02-01

    Freeze concentration is a process of concentrating liquid products by freezing the water content and subsequently removing the so-formed ice crystals from the food system. In dairy processing, this technology offers the advantage of minimizing the heat abuse of sensitive milk components, such as proteins and flavors. It thus provides an opportunity for producing dairy ingredients with enhanced functional and organoleptic qualities. By freeze concentration, skim milk has been concentrated up to 40 wt% total solids (TS) and whole milk up to 44 wt% TS. Lactose and lipids are more concentrated in the ice fraction than in the concentrated fraction. Proteins (casein and whey protein) decrease the ice growth rate and the high viscosity is a limiting factor for the freeze concentration of both skim milk and whole milk. In this study, the most important studies relating to the suspension, block and layer freeze concentration of milk are summarized, analyzing results and indicating how freeze concentration process efficiency of dairy products can be improved. PMID:21364040

  14. Freeze avoidance: a dehydrating moss gathers no ice.

    PubMed

    Lenné, Thomas; Bryant, Gary; Hocart, Charles H; Huang, Cheng X; Ball, Marilyn C

    2010-10-01

    Using cryo-SEM with EDX fundamental structural and mechanical properties of the moss Ceratodon purpureus (Hedw.) Brid. were studied in relation to tolerance of freezing temperatures. In contrast to more complex plants, no ice accumulated within the moss during the freezing event. External ice induced desiccation with the response being a function of cell type; water-filled hydroid cells cavitated and were embolized at -4 °C while parenchyma cells of the inner cortex exhibited cytorrhysis, decreasing to ? 20% of their original volume at a nadir temperature of -20 °C. Chlorophyll fluorescence showed that these winter acclimated mosses displayed no evidence of damage after thawing from -20 °C while GCMS showed that sugar concentrations were not sufficient to confer this level of freezing tolerance. In addition, differential scanning calorimetry showed internal ice nucleation occurred in hydrated moss at ?-12 °C while desiccated moss showed no evidence of freezing with lowering of nadir temperature to -20 °C. Therefore the rapid dehydration of the moss provides an elegantly simple solution to the problem of freezing; remove that which freezes. PMID:20525002

  15. Heritage roundtable: the nuclear freeze

    SciTech Connect

    Allen, R.V.; Gray, C.; Kalicki, J.; Pfaltzgraff, R.; Scoville, H.

    1982-01-01

    The transcript of a panel of foreign policy experts, chaired by former National Security Adviser Richard Allen, debates the proposed nuclear freeze. They consider whether a freeze is a step in the right direction, acting to slow the arms race and contribute to world security, or whether it would aggravate strategic problems by perpetuating an umbalanced situation. Disagreement among the participants makes clear that no one favors nuclear war, but there are differing perspectives on how to continue preventing such a war.

  16. Ultrasonic emissions from conifer xylem exposed to repeated freezing.

    PubMed

    Mayr, Stefan; Zublasing, Verena

    2010-01-01

    Ultrasonic emission measurements enable the analysis of xylem cavitation induced by drought and freeze-thaw events. Several studies have indicated that ultrasonic acoustic emissions (UAE) in conifers occur upon freezing and not upon thawing, although classical theory has postulated gas bubble formation during freezing and cavitation during thawing. We analyzed the pattern and quality of freeze-thaw-induced UAE in seven conifers (Abies alba, Larix decidua, Juniperus communis, Picea abies, Pinus cembra, Pinus mugo, Pinus sylvestris). Axes samples dehydrated to different water potentials were exposed to repeated frost cycles. The number, amplitude and energy of UAE signals were registered and related to water potential, temperature course and wood characteristics (wood density, tracheid diameter). For P. abies, ultrasonic emission analysis was also performed on bark samples, xylem samples without bark, as well as on stems of young potted trees. In all conifers, UAE were registered in water-stressed samples but not in saturated or dehydrated samples. No signals were emitted by the bark of P. abies. Ultrasonic activity occurred only upon freezing, and identical patterns were observed in axes samples and stems of potted P. abies trees. A weak positive relationship between tracheid diameter and UAE energy was observed, indicating wide tracheids to emit signals with higher energy. The classical bubble formation hypothesis cannot sufficiently explain the occurrence of UAE during freezing and upon repeated temperature cycles, as demonstrated in this study. We suggest that the low water potential of ice induces air-seeding near the ice-water interface, and consequently, causes UAE. PMID:19692146

  17. Demonstration and evaluation of germicidal UV-LEDs for point-of-use water disinfection.

    PubMed

    Chatterley, Christie; Linden, Karl

    2010-09-01

    Ultraviolet (UV) irradiation is a common disinfection option for water treatment in the developed world. There are a few systems installed in developing countries for point-of-use treatment, but the low-pressure mercury lamps currently used as the UV irradiation source have a number of sustainability issues including a fragile envelope, a lifetime of approximately one year, and they contain mercury. UV light emitting diodes (LEDs) may offer solutions to many of the sustainability issues presented by current UV systems. LEDs are small, efficient, have long lifetimes, and do not contain mercury. Germicidal UV LEDs emitting at 265 nm were evaluated for inactivation of E. coli in water and compared to conventional low-pressure UV lamps. Both systems provided an equivalent level of treatment. A UV-LED prototype was developed and evaluated as a proof-of-concept of this technology for a point-of-use disinfection option, and the economics of UV-LEDs were evaluated. PMID:20375477

  18. Comparison and validation of point spread models for imaging in natural waters.

    PubMed

    Hou, Weilin; Gray, Deric J; Weidemann, Alan D; Arnone, Robert A

    2008-06-23

    It is known that scattering by particulates within natural waters is the main cause of the blur in underwater images. Underwater images can be better restored or enhanced with knowledge of the point spread function (PSF) of the water. This will extend the performance range as well as the information retrieval from underwater electro-optical systems, which is critical in many civilian and military applications, including target and especially mine detection, search and rescue, and diver visibility. A better understanding of the physical process involved also helps to predict system performance and simulate it accurately on demand. The presented effort first reviews several PSF models, including the introduction of a semi-analytical PSF given optical properties of the medium, including scattering albedo, mean scattering angles and the optical range. The models under comparison include the empirical model of Duntley, a modified PSF model by Dolin et al, as well as the numerical integration of analytical forms from Wells, as a benchmark of theoretical results. For experimental results, in addition to that of Duntley, we validate the above models with measured point spread functions by applying field measured scattering properties with Monte Carlo simulations. Results from these comparisons suggest it is sufficient but necessary to have the three parameters listed above to model PSFs. The simplified approach introduced also provides adequate accuracy and flexibility for imaging applications, as shown by examples of restored underwater images. PMID:18575566

  19. Measurement of water-holding capacity in raw and freeze-dried broiler breast meat with visible and near-infrared spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The feasibility of using visible/near-infrared spectroscopy (vis/NIR) to segregate broiler breast fillets by water-holding capacity (WHC) was determined. Broiler breast fillets (n = 72) were selected from a commercial deboning line based on visual color assessment. Meat color (L*a*b*), pH (2 and 2...

  20. Potential derived point charge model study of electrostatic interaction energies in some complexes of water with uracil, thymine, and cytosine.

    PubMed

    Ray, N K; Bolis, G; Shibata, M; Rein, R

    1984-01-01

    Potential derived (PD) point charges and segmental multipole moments are calculated for water, uracil, thymine, and cytosine using STO-3G quality wave functions. The PD point charges are used to estimate the electrostatic interaction energies for a series of complexes of water with these nucleic acid bases. It is shown here that the results obtained using simple PD charge model is very similar to those obtained from more elaborate segmental multipole moment analysis. PMID:11540815

  1. Realization of the Triple Point of Water in Metallic Sealed Cells at the LNE-INM\\/CNAM: A Progress Report

    Microsoft Academic Search

    F. Sparasci; L. Pitre; Y. Hermier

    2008-01-01

    A miniature metallic cell for the water triple point (TPW, temperature 273.16 K) was developed for capsule-type thermometer\\u000a calibrations for realizations with adiabatic calorimetry techniques. The LNE-INM\\/Cnam previously developed a copper cell for\\u000a the water triple point and the techniques for cleaning, filling, and sealing. On the basis of previous work, a new copper\\u000a cell prototype for the TPW was developed

  2. Chemical stability of amorphous materials: specific and general media effects in the role of water in the degradation of freeze-dried zoniporide.

    PubMed

    Luthra, Suman A; Shalaev, Evgenyi Y; Medek, Ales; Hong, Jinyang; Pikal, Michael J

    2012-09-01

    The objective of the present work was to determine whether hydrolysis in a model lyophile was influenced by general media effects with water-changing properties of the medium or via a specific mechanism of water as a reactant. Four formulations of zoniporide and sucrose (1:10) were prepared with variable amounts of sorbitol [0%-25% (w/v) of total solids). These formulations were then equilibrated at 6% and 11% relative humidity using saturated salt solutions. The lyophile cakes were analyzed by differential scanning calorimetery (DSC), (isothermal microcalorimetry (IMC), solid- state nuclear magnetic resonance (ssNMR) spectroscopy, and ultraviolet-visible diffuse reflectance (DFR) spectroscopy. DSC and IMC were used to assess the global molecular mobility. ssNMR relaxation times were measured to access local mobility. The DFR was used to determine the solid-state acidity expressed as the Hammett acidity function. Stability of samples was evaluated at 40°C by monitoring potency and purity by high-performance liquid chromatography (HPLC). Results were interpreted in terms of the various roles of water: media effect, plasticization, polarity, and reactant. The kinetics of hydrolysis was observed to be correlated with either/both specific "chemical" effects, that is, water reactant as well as media effect, specifically global molecular mobility of the matrix. Increase in reaction rate with increase in water content is not linear and is a weaker dependence than in some hydrolytic reactions in organic solvents. A moderate amount of an inert plasticizer, sorbitol, conferred additional stabilization, possibly by restricting the amplitude and frequency of fast motions that are on a small length scale. PMID:22461087

  3. Global pollution of surface waters from point and nonpoint sources of nitrogen.

    PubMed

    van Drecht, G; Bouwman, A F; Knoop, J M; Meinardi, C; Beusen, A

    2001-11-01

    Global 0.5- by 0.5-degree resolution estimates are presented on the fate of nitrogen (N) stemming from point and nonpoint sources, including plant uptake, denitrification, leaching from the rooting zone, rapid flow through shallow groundwater, and slow flow through deep groundwater to riverine systems. Historical N inputs are used to describe the N flows in groundwater. For nonpoint N sources (agricultural and natural ecosystems), calculations are based on local hydrology, climate, geology, soils, climate and land use combined with data for 1995 on crop production, N inputs from N fertilizers and animal manure, and estimates for ammonia emissions, biological N fixation, and N deposition. For point sources, our estimates are based on population densities and human N emissions, sanitation, and treatment. The results provide a first insight into the magnitude of the N losses from soil-plant systems and point sources in various parts of the world, and the fate of N during transport in atmosphere, groundwater, and surface water. The contribution to the river N load by anthropogenic N pollution is dominant in many river basins in Europe, Asia, and North Africa. Our model results explain much of the variation in measured N export from different world river basins. PMID:12805818

  4. Changes in meat quality of ovine longissimus dorsi muscle in response to repeated freeze and thaw.

    PubMed

    Qi, Jun; Li, Chunbao; Chen, Yinji; Gao, Feifei; Xu, Xinglian; Zhou, Guanghong

    2012-12-01

    Changes in eating and technological quality attributes of ovine longissimus dorsi muscle during repeated freeze and thaw were investigated. Shear force value, L* value, a* value and fiber diameter decreased (P<0.05) but lipid oxidation increased (P<0.05) with repeated freeze-thaw cycles. Sarcomere length and pH decreased (P<0.05) within the first 10 freeze-thaw cycles but increased (P<0.05) after 5 further cycles. Total and myofibrillar protein solubility, and intramuscular free fatty acids concentration decreased (P<0.05) after 1 cycle of freeze and thaw but then increased (P<0.05) gradually with further cycles. Hardness, chewiness, cohesiveness and resilience of comminuted lamb products decreased (P<0.05) with increased freeze-thaw cycles. And therefore, repeated freeze and thaw should be minimized in terms of meat color for commercial value and water holding capacity for further processing. PMID:22749539

  5. Assessing point-of-use ultraviolet disinfection for safe water in urban developing communities.

    PubMed

    Barstow, Christina K; Dotson, Aaron D; Linden, Karl G

    2014-12-01

    Residents of urban developing communities often have a tap in their home providing treated and sometimes filtered water but its microbial quality cannot be guaranteed. Point-of-use (POU) disinfection systems can provide safe drinking water to the millions who lack access to clean water in urban communities. While many POU systems exist, there are several concerns that can lead to low user acceptability, including low flow rate, taste and odor issues, high cost, recontamination, and ineffectiveness at treating common pathogens. An ultraviolet (UV) POU system was constructed utilizing developing community-appropriate materials and simple construction techniques based around an inexpensive low-wattage, low pressure UV bulb. The system was tested at the bench scale to characterize its hydrodynamic properties and microbial disinfection efficacy. Hydraulically the system most closely resembled a plug flow reactor with minor short-circuiting. The system was challenge tested and validated for a UV fluence of 50 mJ/cm(2) and greater, over varying flow rates and UV transmittances, corresponding to a greater than 4 log reduction of most pathogenic bacteria, viruses, and protozoa of public health concern. This study presents the designed system and testing results to demonstrate the potential architecture of a low-cost, open-source UV system for further prototyping and field-testing. PMID:25473974

  6. Accuracy of tropospheric and stratospheric water vapor measurements by the cryogenic frost point hygrometer: Instrumental details and observations

    Microsoft Academic Search

    H. Vömel; D. E. David; K. Smith

    2007-01-01

    The cryogenic frost point hygrometer (CFH), currently built at the University of Colorado, is a new balloon borne hygrometer, which is capable of continuously measuring water vapor between the surface and the middle stratosphere. The design is loosely based on the old NOAA\\/CMDL frost point hygrometer, with improved accuracy and a number of significant new features that overcome some limitations

  7. Combined Microwave-Vacuum and Freeze Drying of Carrot and Apple Chips

    Microsoft Academic Search

    Zheng-Wei Cui; Chun-Yang Li; Chun-Fang Song; Yun Song

    2008-01-01

    A combination of microwave-vacuum (MWV) drying and freeze drying was investigated as potential means for drying carrot and apple chips. The sample was first dried by microwave-vacuum to dehydrate some amount of internal free water and then by freeze drying to a final moisture content of less than 7% (wet basis). Chemical properties (carotene and vitamin C retention) and physical

  8. Dehydration of carrots by a combination of freeze drying, microwave heating and air or vacuum drying

    Microsoft Academic Search

    S. Litvin; C. H. Mannheim; J. Miltz

    1998-01-01

    Carrot slices were dried by combining freeze drying with a short microwave treatment and air or vacuum drying. Total drying time, and quality parameters including color, dimensions of slices and rehydration ratio were determined.Freeze drying for 2 h at a plate temperature of 30 °C followed by 1.5 h at 55 °C was sufficient to remove all water by sublimation

  9. Heterogeneous freezing of ammonium sulfate and sodium chloride solutions by long chain alcohols

    Microsoft Academic Search

    Will Cantrell; Carly Robinson

    2006-01-01

    High molecular weight organic compounds emitted during biomass burning can be transported to high altitudes where they may affect ice processes through heterogeneous nucleation. We show that freezing of solutions of ammonium sulfate and sodium chloride catalyzed by long chain alcohols is roughly consistent with the hypothesis that the water activity at the mean freezing temperature is a constant offset

  10. MEASUREMENT AND NUMERICAL ANALYSIS OF FREEZING IN SOLUTIONS ENCLOSED IN A SMALL CONTAINER

    E-print Network

    Water. #12;Freezing in Biological Solutions 3 Nomenclature Symbol Definition Value/Units B Constant. Tel: (612) 625 5513; Fax: (612) 624 1398; Email: bischof@maroon.tc.umn.edu #12;Freezing in Biological and further elucidates the measured temperature and time dependence of the latent heat release. Key Words

  11. An improved microscope stage for direct observation of freezing and freeze drying.

    PubMed

    Nail, S L; Her, L M; Proffitt, C P; Nail, L L

    1994-08-01

    A microscope stage for observation of freezing and freeze drying is described. The stage uses thermoelectric (Peltier) heaters configured in two stages, with circulating fluid as a heat sink on the high temperature side. Lowest attainable sample temperature is about -47 degrees C. Principal advantages of this system are closed-loop control of stage temperature, rapid response to changes in temperature set point, and improved documentation of experiments by use of a video recorder system with a character generator which allows display of sample identity and temperature. Accuracy of measuring the sample temperature in the field of view was validated by comparing observed values of eutectic melting with published values for a series of solutes with eutectic temperatures in the range from -2 degrees C to -32 degrees C. Good agreement was obtained throughout this range. PMID:7971708

  12. Glass Transitions and State Diagram for Freeze-dried Pineapple

    Microsoft Academic Search

    V. R. N. Telis; P. J. A. Sobral

    2001-01-01

    Glass transition temperature of freeze-dried pineapple conditioned by adsorption at various water activities at 25 °C was determined by differential scanning calorimetry (DSC). High moisture content samples corresponding to water activities higher than 0.9, obtained by liquid water addition, were also analysed. The DSC traces showed a well-visible shift in baseline at the glass transition temperature (Tg). Besides, no ice

  13. Synchrotron X-Ray Visualisation of Ice Formation in Insects during Lethal and Non-Lethal Freezing

    PubMed Central

    Sinclair, Brent J.; Gibbs, Allen G.; Lee, Wah-Keat; Rajamohan, Arun; Roberts, Stephen P.; Socha, John J.

    2009-01-01

    Although the biochemical correlates of freeze tolerance in insects are becoming well-known, the process of ice formation in vivo is subject to speculation. We used synchrotron x-rays to directly visualise real-time ice formation at 3.3 Hz in intact insects. We observed freezing in diapausing 3rd instar larvae of Chymomyza amoena (Diptera: Drosophilidae), which survive freezing if it occurs above ?14°C, and non-diapausing 3rd instar larvae of C. amoena and Drosophila melanogaster (Diptera: Drosophilidae), neither of which survive freezing. Freezing was readily observed in all larvae, and on one occasion the gut was seen to freeze separately from the haemocoel. There were no apparent qualitative differences in ice formation between freeze tolerant and non-freeze tolerant larvae. The time to complete freezing was positively related to temperature of nucleation (supercooling point, SCP), and SCP declined with decreasing body size, although this relationship was less strong in diapausing C. amoena. Nucleation generally occurred at a contact point with the thermocouple or chamber wall in non-diapausing larvae, but at random in diapausing larvae, suggesting that the latter have some control over ice nucleation. There were no apparent differences between freeze tolerant and non-freeze tolerant larvae in tracheal displacement or distension of the body during freezing, although there was markedly more distension in D. melanogaster than in C. amoena regardless of diapause state. We conclude that although control of ice nucleation appears to be important in freeze tolerant individuals, the physical ice formation process itself does not differ among larvae that can and cannot survive freezing. This suggests that a focus on cellular and biochemical mechanisms is appropriate and may reveal the primary adaptations allowing freeze tolerance in insects. PMID:20011523

  14. ANNAGNPS: ACCOUNTING FOR SNOWPACK, SNOWMELT, FREEZING AND THAWING OF SOIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The watershed model, AnnAGNPS (Annualized AGricultural Non-Point Source Pollution model) has been enhanced by incorporating winter climate algorithms that account for frozen soil conditions. The model includes snowpack accumulation and melt, and the freeze/thaw process in the soil. Three major imp...

  15. Heat and mass transfer characteristics of a new combined absorber-evaporator exchanger operating near the triple point of water

    Microsoft Academic Search

    Y.-M. Chen; C.-Y. Sun

    1996-01-01

    The present experimental study investigates the controlling mechanism involved in a new combined vertical film-type absorber-evaporator exchanger operating near the condition of the triple point of water. This peculiar exchanger plays the most important role in the VFVPE process that can be utilized in many industrial applications, water pollution prevention, desalination, and purification of chemicals, for example. The method of

  16. 1. Coastal waters are often exposed to heavy metals (HM) introduced from point and diffusive sources. Chronic and

    E-print Network

    Einat, Aharonov

    1. Coastal waters are often exposed to heavy metals (HM) introduced from point and diffusive and ALF3-ALF6. Sampling during 04/2004 5. Heavy metals concentration in Amphistegina lobifera is far higher than in sea water. Heavy metals concentration in seawater 4. Most of the dissolved heavy metals

  17. Calculation of photon energy deposition kernels and electron dose point kernels in water.

    PubMed

    Mainegra-Hing, Ernesto; Rogers, D W O; Kawrakow, Iwan

    2005-03-01

    Effects of changes in the physics of EGSnrc compared to EGS4/PRESTA on energy deposition kernels for monoenergetic photons and on dose point kernels for beta sources in water are investigated. In the diagnostic energy range, Compton binding corrections were found to increase the primary energy fraction up to 4.5% at 30 keV with a corresponding reduction of the scatter component of the kernels. Rayleigh scattered photons significantly increase the scatter component of the kernels and reduce the primary energy fraction with a maximum 12% reduction also at 30 keV where the Rayleigh cross section in water has its maximum value. Sampling the photo-electron angular distribution produces a redistribution of the energy deposited by primaries around the interaction site causing differences of up to 2.7 times in the backscattered energy fraction at 20 keV. Above the pair production threshold, the dose distribution versus angle of the primary dose component is significantly different from the EGS4 results. This is related to the more accurate angular sampling of the electron-positron pair direction in EGSnrc as opposed to using a fixed angle approximation in default EGS4. Total energy fractions for photon beams obtained with EGSnrc and EGS4 are almost the same within 0.2%. This fact suggests that the estimate of the total dose at a given point inside an infinite homogeneous water phantom irradiated by broad beams of photons will be very similar for kernels calculated with both codes. However, at interfaces or near boundaries results can be very different especially in the diagnostic energy range. EGSnrc calculated kernels for monoenergetic electrons (50 keV, 100 keV, and 1 MeV) and beta spectra (32P and 90Y) are in excellent agreement with reported EGS4 values except at 1 MeV where inclusion of spin effects in EGSnrc produces an increase of the effective range of electrons. Comparison at 1 MeV with an ETRAN calculation of the electron dose point kernel shows excellent agreement. PMID:15839340

  18. Integrated watershed approach in controlling point and non-point source pollution within Zelivka drinking water reservoir

    Microsoft Academic Search

    J. Holas; M. Hrncir

    An agricultural watershed involves manipulation of soil, water and other natural resources and it has profound impacts on ecosystems. To manage these complex issues, we must understand causes and consequences and interactions-related transport of pollutants, quality of the environment, mitigation measures and policy measures. A ten year period of economic changes has been analysed with respect to sustainable development concerning

  19. Dose Point Kernels in liquid water:1 an intra-comparison between GEANT4-DNA and a variety of Monte Carlo codes2

    E-print Network

    Paris-Sud XI, Université de

    1 Dose Point Kernels in liquid water:1 an intra-comparison between GEANT4-DNA and a variety water, the simulation of electron Dose Point Kernels remains the27 preferential test. In this work: Dose Point Kernel; Geant4-DNA; Monte Carlo codes; liquid water.134 135 136 PACS: 87.53.Bn; 02.70.Ss; 87

  20. Water-quality, water-level, and lake-bottom-sediment data collected from the defense fuel supply point and adjacent properties, Hanahan, South Carolina, 1990-96

    USGS Publications Warehouse

    Petkewich, M.D.; Vroblesky, D.A.; Robertson, J.F.; Bradley, P.M.

    1997-01-01

    A 9-year scientific investigation to determine the potential for biore-mediation of ground-water contamination and to monitor the effectiveness of an engineered bioremediation system located at the Defense Fuel Supply Point and adjacent properties in Hanahan, S.C., has culminated in the collection of abundant water-quality and water-level data.This report presents the analytical results of the study that monitored the changes in surface- and ground-water quality and water-table elevations in the study area from December 1990 to January 1996. This report also presents analytical results of lake-bottom sediments collected in the study area.

  1. Selection of an adsorbent for lead removal from drinking water by a point-of-use treatment device

    Microsoft Academic Search

    Renaud Sublet; Marie-Odile Simonnot; Alain Boireau; Michel Sardin

    2003-01-01

    The removal of lead from drinking water was investigated to develop a point-of-use water filter that could meet the regulation imposed by the new European Directive 98-83 lowering lead concentration in drinking water below 10?gL?1. The objective of this research was to assess the potential of different adsorbents (zeolites, resins, activated carbon, manganese oxides, cellulose powder) to remove lead from

  2. Investigation of Microcrystalline Cellulose as Ice Nucleus in Immersion Freezing Processes

    NASA Astrophysics Data System (ADS)

    Häusler, Thomas; Khaybulkina, Evgeniya; Felgitsch, Laura; Bichler, Magdalena; Grothe, Hinrich

    2015-04-01

    Aerosol-cloud interactions play an important role in earth's radiation balance. Aerosol particles act as cloud condensation nuclei for liquid droplets and/or as ice nuclei for the formation of ice particles. Previous research in our group has been related to biological ice nucleation.1-3 Here, we present a proxy for many biological macromolecular substances, i.e. microcrystalline cellulose. Due to the chemical convenience of cellulose compared to other biological ice nuclei, basic, but still unknown ice nucleation mechanisms can be investigated. Cellulose is a polysaccharide consisting of a linear chain of several hundred to many thousands of ?(1?4) linked D-glucose units. It is an important structural element of the primary cell wall of green plants, many forms of algae and the oomycetes. Several types of microcrystalline cellulose were analysed and investigated due to their physico-chemical properties. Immersion freezing experiments were carried out in a unique reaction gadget. In this device a water-in-oil suspension (with the cellulose suspended in the aqueous phase) was cooled till the freezing point and was observed through a microscope. The results of the immersion freezing experiments of the different cellulose types showed variable ice nucleation activities depending on their morphology (e.g. particle size) and their concentration. Further analysis methods as scanning electron microscopy (SEM) and small angle X-ray scattering (SAX) were carried out to entirely describe the cellulose and their ice nucleation activity. [1] S.Augustin, H. Wex, D. Niedermeier, B. Pummer, H.Grothe, S. Hartmann, L. Tomsche, T. Clauss, J. Voigtländer, K. Ingatius, and F. Stratmann. Immersion freezing of birch pollen washing water. Atmospheric Chemistry Physics 2013, 13, 10989-11003 [2] B. Pummer, L. Atanasova, H. Bauer, H. Bernardi, I. S. Druzhinina, J. Froehlich-Nowoisky, H. Grothe. Spores of many common airborne fungi reveal no ice nucleation activity in oil immersion freezing experiments. Biogeosciences 2013, 10, 8083- 8091 [3] B. Pummer, H. Baue, J. Bernardi, S. Bleicher, H. Grothe. Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen. Atmospheric Chemistry Physics 2012, 12, 2541-2550

  3. Statistical rate theory determination of water properties below the triple point.

    PubMed

    Duan, Fei; Thompson, Ian; Ward, C A

    2008-07-24

    We report a new method for determining the saturation vapor pressure, Ps(T), of water at conditions below its triple point. Ps(T) appears as a parameter in the statistical rate theory (SRT) expression for the net evaporation flux. We use measurements of the interfacial conditions during steady-state evaporation and condensation experiments and SRT to determine the values of Ps(T) from 50 different experiments over a range of interfacial conditions. From these values of Ps(T), we develop an analytical expression and from it calculate the liquid-vapor latent heat, Llv(T), and the constant pressure specific heat, cp(L)(T). The calculated values of these properties are compared with those obtained from independent measurements. This comparison indicates the SRT expressions for Llv(T) and cp(L)(T) are consistent with the measurements over a range of temperatures. PMID:18582005

  4. Calculation of electron Dose Point Kernel in water with GEANT4 for medical application

    NASA Astrophysics Data System (ADS)

    Guimarães, C. C.; Moralles, M.; Sene, F. F.; Martinelli, J. R.; Okuno, E.

    2009-06-01

    The rapid insertion of new technologies in medical physics in the last years, especially in nuclear medicine, has been followed by a great development of faster Monte Carlo algorithms. GEANT4 is a Monte Carlo toolkit that contains the tools to simulate the problems of particle transport through matter. In this work, GEANT4 was used to calculate the dose-point-kernel (DPK) for monoenergetic electrons in water, which is an important reference medium for nuclear medicine. The three different physical models of electromagnetic interactions provided by GEANT4—Low Energy, Penelope and Standard—were employed. To verify the adequacy of these models, the results were compared with references from the literature. For all energies and physical models, the agreement between calculated DPKs and reported values is satisfactory.

  5. Calculation of electron Dose Point Kernel in water with GEANT4 for medical application

    SciTech Connect

    Guimaraes, C. C.; Sene, F. F.; Martinelli, J. R. [Centro de Ciencia e Tecnologia de Materiais, IPEN/CNEN, CEP 05422-970, SP (Brazil); Moralles, M. [Centro do Reator de Pesquisas, IPEN/CNEN, CEP 05422-970, SP (Brazil); Okuno, E. [Instituto de Fisica, USP, Rua do Matao, Travessa R, 187. CEP 05508-090, SP (Brazil)

    2009-06-03

    The rapid insertion of new technologies in medical physics in the last years, especially in nuclear medicine, has been followed by a great development of faster Monte Carlo algorithms. GEANT4 is a Monte Carlo toolkit that contains the tools to simulate the problems of particle transport through matter. In this work, GEANT4 was used to calculate the dose-point-kernel (DPK) for monoenergetic electrons in water, which is an important reference medium for nuclear medicine. The three different physical models of electromagnetic interactions provided by GEANT4 - Low Energy, Penelope and Standard - were employed. To verify the adequacy of these models, the results were compared with references from the literature. For all energies and physical models, the agreement between calculated DPKs and reported values is satisfactory.

  6. Effects of freezing rates and cryoprotectant on thermal expansion of articular cartilage during freezing process.

    PubMed

    Xu, Y; Sun, H J; Lv, Y; Zou, J C; Lin, B L; Hua, T C

    2013-01-01

    The intact articular cartilage has not yet been successfully preserved at low temperature most likely due to the volume expansion from water to ice during freezing. The objective of this current study focuses on examining thermal expansion behavior of articular cartilage (AC) during freezing from 0 degree C to -100 degree C. Thermo Mechanical Analysis (TMA) was used to investigate the effects of different concentrations of dimethyl sulphoxide (DMSO) (0%, 10%, 30% and 60% v/v) and different freezing rates (1 C/min, 3 C/min and 5 C/min). The results showed that: (1) the inhomogeneous thermal expansion (or contraction) presents due to inhomogeneous water distributions in articular cartilage during freezing, which also may be the most likely reason that the matrix has been damaged in cryopreserved intact articular cartilage; (2) at the phase transition temperature range, the maximum thermal strain change value for 5C/min is approximately 1.45 times than that for 1 C/min, but the maximum thermal expansion coefficient of the later is about six times than that of the former; (3) the thermal expansion coefficient decreases with increasing cooling rate at the unfrozen temperature region, but some opposite results are obtained at the frozen temperature region; (4) the higher the DMSO concentration is, at the phase change temperature region, the smaller the thermal strain change as well as the maximum thermal expansion coefficient are, but DMSO concentration exhibits little effect on the thermal expansion coefficient at both unfrozen and frozen region. Once the DMSO concentration increasing enough, e.g. 60% v/v, the thermal strain decreases linearly and smoothly without any abrupt change due to little or no ice crystal forms (i.e. vitrification) in frozen articular cartilage. This study may improve our understanding of the thermal expansion (or contraction) behavior of cryopreserved articular cartilage and it may be useful for the future study on cryopreservation of intact articular cartilage. PMID:23995399

  7. Capture of activity-induced ultrastructural changes at synapses by high-pressure freezing of brain tissue.

    PubMed

    Studer, Daniel; Zhao, Shanting; Chai, Xuejun; Jonas, Peter; Graber, Werner; Nestel, Sigrun; Frotscher, Michael

    2014-01-01

    Electron microscopy (EM) allows for the simultaneous visualization of all tissue components at high resolution. However, the extent to which conventional aldehyde fixation and ethanol dehydration of the tissue alter the fine structure of cells and organelles, thereby preventing detection of subtle structural changes induced by an experiment, has remained an issue. Attempts have been made to rapidly freeze tissue to preserve native ultrastructure. Shock-freezing of living tissue under high pressure (high-pressure freezing, HPF) followed by cryosubstitution of the tissue water avoids aldehyde fixation and dehydration in ethanol; the tissue water is immobilized in ?50 ms, and a close-to-native fine structure of cells, organelles and molecules is preserved. Here we describe a protocol for HPF that is useful to monitor ultrastructural changes associated with functional changes at synapses in the brain but can be applied to many other tissues as well. The procedure requires a high-pressure freezer and takes a minimum of 7 d but can be paused at several points. PMID:24874814

  8. History of Debris-bearing Basal ice: Comparing Numerical Simulations of Basal Freeze-on to Borehole Video Images and Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Christoffersen, P.; Tulaczyk, S.

    2002-12-01

    Debris-bearing basal ice are frequently observed in a variety of glaciers as well as in ice cores drilled to the base of modern ice sheets. A common feature of frozen-on basal ice is an layered structure of debris-rich, dirty ice and clean, transparent ice. The thermodynamic aspects governing the segregation mechanism that separates dirty ice and clean ice are poorly understood and quantitative assessments of basal freeze-on are rarely conducted. We have investigated the response of subglacial sediments to basal freeze-on in a high-resolution numerical model (node spacing: 0.01 m). The model adapts thermodynamics of frost heave (which is a much-studied process in permafrost engineering) to subglacial conditions. In fine-grained sub-ice stream till, in-situ freezing of pore water is inhibited due to surface tension arising from a small characteristic particle size. The till becomes super-cooled by up to -0.35°C from the pressure-melting point and thermally driven pore water flow is induced. This water flow feeds accretion of clean ice onto the ice base while the till dewaters. Our model predictions compare favorably with observations from the Ross sector of the West Antarctic ice sheet. When the ice base is in direct contact with the till, ice stream stoppage is predicted to occur ca. 70 years after basal freeze-on is triggered. Fast ice stream flow may be prolonged if a widespread basal water system is capable of separating the freezing ice base from the till. However, the small thickness of water filled gaps (ca. 1-2 mm) limits the time of enhanced flow prolongation. After the freezing ice base has consumed the water film, the ice stream will shut down due to dewatering of the till. However, the bed remains unfrozen and highly porous for long time periods subsequent to stoppage. We predict that complete freeze-up of a 5 m till layer takes several centuries. This result is supported by radar data showing that Ice Stream C, which stopped ca. 150 years ago, has a largely unfrozen bed, while Siple Ice Stream, which stopped about 300 years earlier, exhibits a partially frozen bed. A self-adjusting upper boundary in our numerical simulation allows the freezing front to move downwards into the till domain. This occurs when the ice-till interface is no longer the thermodynamically most favorable location for freezing. We can thus simulate growth of ice lenses within the till. Our model reproduces basal ice with a layered structure consisting of uniform bands of debris-filled ice and clean segregation ice. Medium-grained till develops thin ice lenses that are closely spaced while fine-grained till develops thick ice lenses with a wider spacing. Comparison of our results to borehole video images of basal ice beneath Ice Stream C and images from laboratory studies of freezing porous media indicates that thermodynamics of basal freeze-on and frost heaving are fundamentally related.

  9. Freeze-drying of bioproducts: putting principles into practice

    Microsoft Academic Search

    Felix Franks

    1998-01-01

    The product and process parameters that determine successful freeze-drying are described and their interrelationships are explored. It is shown that the thermochemical and thermomechanical properties of water-soluble, amorphous materials form the basis of effective formulation design and that coordinated approaches to formulation and process development achieve optimum results with a minimum of trial-and-error experimentation.

  10. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    Cracks shown here in the exterior and supporting structures of this home are indicative of subsidence damage associated with sinkhole activity. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting l...

  11. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    A section of a strawberry field that was destroyed by a sinkhole and filled in, as is done with many sinkholes if possible. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows as farmers pump...

  12. Sinkholes in West-central Florida, Freeze Event of 2010

    USGS Multimedia Gallery

    Sinkholes affect structures as well as many types of supporting infrastructure such as buried utilities lines seen here. More than 110 sinkholes formed in the Dover area of Florida during a freeze event in January 2010. Ground water levels dropped to record-setting lows ...

  13. COMBINED REVERSE OSMOSIS AND FREEZE CONCENTRATION OF BLEACH PLANT EFFLUENTS

    EPA Science Inventory

    Reverse osmosis (RO) and freeze concentration (FC) were evaluated at three different pulp and paper mills as tools for concentrating bleach plant effluents. By these concentration processes, the feed effluent was divided into two streams. The clean water stream approached drinkin...

  14. Plant cover, soil temperature, freeze, water stress, and evapotranspiration conditions. [Lower Rio Grande Valley Test Site: Weslaco, Texas; Falco Reservoir and the Gulf of Mexico

    NASA Technical Reports Server (NTRS)

    Wiegand, C. L.; Nixon, P. R.; Gausman, H. W.; Namken, L. N.; Leamer, R. W.; Richardson, A. J. (principal investigators)

    1980-01-01

    The author has identified the following significant results. HCMM day/night coverage 12 hours apart cannot be obtained at 26 deg N latitude; nor have any pairs 36 hours apart been obtained. A day-IR scene and a night scene for two different dates were analyzed. A profile across the test site for the same latitude shows that the two profiles are near mirror images of each other over land surfaces and that the temperature of two large water bodies, Falcon Reservoir and the Gulf of Mexico, are nearly identical on two dates. During the time interval between overpasses, the vegetative cover remained static due to winter dormancy. The data suggest that day/night temperature differences measured weeks apart may yield meaningful information about the contrast between daytime maximum and nighttime minimum temperatures for a given site.

  15. Including non-point sfources in a water quality trading permit program.

    PubMed

    Collentine, D

    2005-01-01

    There has been overwhelming interest in addressing water quality issues through the use of economic instruments. Much of this attention has focused on the cost efficiencies offered by Transferable Discharge Permit (TDP) systems. Unfortunately, the attempts to start up permit markets which are able to exploit abatement cost differences between sources have not met with the success expected. Two of the reasons for the lack of success that have been taken up in analysis of these programs have been the problem of transaction costs and in the case of non-point sources (NPS), undefined property rights. The composite market design is a proposal for a TDP system which specifically includes agricultural non-point source (NPS) dischargers and addresses both property rights and transaction cost problems. The composite market consists of three interrelated markets each serving a particular function. When the composite market is mature, the total number of permits issued represents the cap on discharges allowed in the catchment. The structure of the composite market allows this system to be phased in over time with existing institutions and limited demands on financing. PMID:15850173

  16. An Experimental Investigation of the Long-Term Stability of Triple-Point-of-Water Cells

    NASA Astrophysics Data System (ADS)

    Hill, K. D.

    2014-04-01

    Contamination of triple-point-of-water (TPW) cells by the chemical components of the borosilicate glass that contains the water is now widely recognized as the principal contributor to long-term drift of the cell temperature. To add to the available experimental data, a comparison of 24 TPW cells of various ages (from 10 years to 59 years), manufacturers (NRC, Jarrett, Isotech), and materials (borosilicate glass and fused quartz) was undertaken in 2013. Twelve cells from this group were compared to one another in 1997. By comparing the current inter-cell temperature differences to those determined 16 years earlier, it was found that some cells have remained stable, others have become colder (as might be expected from ongoing dissolution of the glass), and one or two show an apparent increase in temperature that seems anomalous. Also included among the 24 cells are five cells of borosilicate glass and five of fused quartz that were purchased 10 years ago. By comparing the relative temperature differences among this group of borosilcate and fused-quartz-encapsulated cells to the values obtained when they were last compared 6 years ago, it was found that the average temperature of the borosilcate group of cells decreases by , in reasonable agreement with an average drift of suggested 12 years ago. It was concluded that fused quartz is the superior container for TPW cells.

  17. Water quality along a river continuum subject to point and diffuse sources

    NASA Astrophysics Data System (ADS)

    Neal, Colin; Jarvie, Helen P.; Love, Alison; Neal, Margaret; Wickham, Heather; Harman, Sarah

    2008-02-01

    SummaryThe water quality along the River Kennet, in the Thames basin of southern England, was examined in terms of the influence of point- and diffuse-nutrient inputs. The river is supplied mainly from a Cretaceous Chalk aquifer and hence the waters are of a calcium bicarbonate type. The nitrate largely comes from agricultural sources, with concentrations decreasing downstream due to plant uptake and probable denitrification. In contrast, soluble reactive phosphorus (SRP) is largely associated with sewage inputs and concentrations increase downstream in line with effluents from major towns such as Newbury and Reading. Adjacent to the river in the lower half of the catchment is the Kennet and Avon Canal and the two are in places hydrologically connected. The canal inputs may influence calcium carbonate (calcite) precipitation and increase suspended sediment and particulate phosphorus concentrations in the river. Monitoring upstream and downstream of Marlborough sewage treatment works (STW) showed that SRP concentrations in the effluent were highly variable due to variable efficiency of P stripping and still sufficiently concentrated to dominate downstream river SRP with potential impacts on stream ecology. Biological recovery in this river following P stripping at STWs is complex and controlling those spikes in SRP that are above a threshold of 100 ?g l -1 may be a critical requirement. More stringent effluent targets than are currently recommended may be needed (less than 800 ?g RP l -1) to achieve good ecological status in this river depending on SRP concentrations upstream.

  18. Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view

    SciTech Connect

    Chen, Yu-Chun; Tang, Ping-Han [Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan (China)] [Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan (China); Wu, Ten-Ming, E-mail: tmw@faculty.nctu.edu.tw [Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan (China) [Institute of Physics, National Chiao-Tung University, Hsinchu 300, Taiwan (China); National Center for Theoretical Sciences, Hsinchu 300, Taiwan (China)

    2013-11-28

    By exploiting the instantaneous normal mode (INM) analysis for models of flexible molecules, we investigate intermolecular and intramolecular vibrations of water from the atomic point of view. With two flexible SPC/E models, our investigations include three aspects about their INM spectra, which are separated into the unstable, intermolecular, bending, and stretching bands. First, the O- and H-atom contributions in the four INM bands are calculated and their stable INM spectra are compared with the power spectra of the atomic velocity autocorrelation functions. The unstable and intermolecular bands of the flexible models are also compared with those of the SPC/E model of rigid molecules. Second, we formulate the inverse participation ratio (IPR) of the INMs, respectively, for the O- and H-atom and molecule. With the IPRs, the numbers of the three species participated in the INMs are estimated so that the localization characters of the INMs in each band are studied. Further, by the ratio of the IPR of the H atom to that of the O atom, we explore the number of involved OH bond per molecule participated in the INMs. Third, by classifying simulated molecules into subensembles according to the geometry of their local environments or their H-bond configurations, we examine the local-structure effects on the bending and stretching INM bands. All of our results are verified to be insensible to the definition of H-bond. Our conclusions about the intermolecular and intramolecular vibrations in water are given.

  19. Mechanism of freeze-thaw instability of aluminum hydroxycarbonate and magnesium hydroxide gels.

    PubMed

    Zapata, M I; Feldkamp, J R; Peck, G E; White, J L; Hem, S L

    1984-01-01

    The effect of freeze-thaw cycles on the physical stability of aluminum hydroxycarbonate and magnesium hydroxide gels was studied. Coagulation following a freeze-thaw cycle, leading to the formation of visible aggregates, affected the content uniformity of both gels. The freeze-thaw cycles did not affect the crystal form or surface characteristics of the gels as determined by X-ray powder diffraction and point of zero charge, but caused a slight reduction in the rate of acid neutralization and a large increase in the rate of sedimentation. The greatest effect was observed after the first freeze-thaw cycle. While the duration of freezing was not a factor, the rate of freezing was important and was inversely related to the aggregate size. The aggregates which formed following a freeze-thaw cycle were not redispersed by shaking, but were reversed by ultrasonic treatment or homogenization. The adsorption of polymers or surface-active agents prior to freezing reduced and, in some cases, prevented the formation of aggregates. The physical instability produced by a freeze-thaw cycle was explained by the modified DLVO theory. The force exerted on the particles by the growing ice crystals forced the particles into the primary minimum, producing strong interparticle attraction. On thawing, simple agitation did not provide enough force to overcome the attractive force of the primary minimum. Adsorption of polymers or surface-active agents increased the steric repulsive force and prevented the particles from reaching the primary minimum. PMID:6694078

  20. Source to point of use drinking water changes and knowledge, attitude and practices in Katsina State, Northern Nigeria

    NASA Astrophysics Data System (ADS)

    Onabolu, B.; Jimoh, O. D.; Igboro, S. B.; Sridhar, M. K. C.; Onyilo, G.; Gege, A.; Ilya, R.

    In many Sub-Saharan countries such as Nigeria, inadequate access to safe drinking water is a serious problem with 37% in the region and 58% of rural Nigeria using unimproved sources. The global challenge to measuring household water quality as a determinant of safety is further compounded in Nigeria by the possibility of deterioration from source to point of use. This is associated with the use of decentralised water supply systems in rural areas which are not fully reticulated to the household taps, creating a need for an integrated water quality monitoring system. As an initial step towards establishing the system in the north west and north central zones of Nigeria, The Katsina State Rural Water and Sanitation Agency, responsible for ensuring access to safe water and adequate sanitation to about 6 million people carried out a three pronged study with the support of UNICEF Nigeria. Part 1 was an assessment of the legislative and policy framework, institutional arrangements and capacity for drinking water quality monitoring through desk top reviews and Key Informant Interviews (KII) to ascertain the institutional capacity requirements for developing the water quality monitoring system. Part II was a water quality study in 700 households of 23 communities in four local government areas. The objectives were to assess the safety of drinking water, compare the safety at source and household level and assess the possible contributory role of end users’ Knowledge Attitudes and Practices. These were achieved through water analysis, household water quality tracking, KII and questionnaires. Part III was the production of a visual documentary as an advocacy tool to increase awareness of the policy makers of the linkages between source management, treatment and end user water quality. The results indicate that except for pH, conductivity and manganese, the improved water sources were safe at source. However there was a deterioration in water quality between source and point of use in 18%, 12.5%, 27% and 50% of hand pump fitted boreholes, motorised boreholes, hand dug wells and streams respectively. Although no statistical correlation could be drawn between water management practices and water quality deterioration, the survey of the study households gave an indication of the possible contributory role of their knowledge, attitudes and practices to water contamination after provision. Some of the potential water related sources of contamination were poor source protection and location, use of unimproved water source and poor knowledge and practice of household water treatment methods, poor hand washing practices in terms of percentage that wash hands and use soap. Consequently 34 WASH departments have been created at the local government level towards establishment of a community based monitoring system and piloting has begun in Kaita local government area.

  1. Freeze/Thaw-induced embolism: probability of critical bubble formation depends on speed of ice formation.

    PubMed

    Sevanto, Sanna; Holbrook, N Michele; Ball, Marilyn C

    2012-01-01

    Bubble formation in the conduits of woody plants sets a challenge for uninterrupted water transportation from the soil up to the canopy. Freezing and thawing of stems has been shown to increase the number of air-filled (embolized) conduits, especially in trees with large conduit diameters. Despite numerous experimental studies, the mechanisms leading to bubble formation during freezing have not been addressed theoretically. We used classical nucleation theory and fluid mechanics to show which mechanisms are most likely to be responsible for bubble formation during freezing and what parameters determine the likelihood of the process. Our results confirm the common assumption that bubble formation during freezing is most likely due to gas segregation by ice. If xylem conduit walls are not permeable to the salts expelled by ice during the freezing process, osmotic pressures high enough for air seeding could be created. The build-up rate of segregated solutes in front of the ice-water interface depends equally on conduit diameter and freezing velocity. Therefore, bubble formation probability depends on these variables. The dependence of bubble formation probability on freezing velocity means that the experimental results obtained for cavitation threshold conduit diameters during freeze/thaw cycles depend on the experimental setup; namely sample size and cooling rate. The velocity dependence also suggests that to avoid bubble formation during freezing trees should have narrow conduits where freezing is likely to be fast (e.g., branches or outermost layer of the xylem). Avoidance of bubble formation during freezing could thus be one piece of the explanation why xylem conduit size of temperate and boreal zone trees varies quite systematically. PMID:22685446

  2. High rates of energy expenditure and water flux in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea

    USGS Publications Warehouse

    Crocker, D.E.; Kofahl, N.; Fellers, G.D.; Gates, N.B.; Houser, D.S.

    2007-01-01

    We measured water flux and energy expenditure in free-ranging Point Reyes mountain beavers Aplodontia rufa phaea by using the doubly labeled water method. Previous laboratory investigations have suggested weak urinary concentrating ability, high rates of water flux, and low basal metabolic rates in this species. However, free-ranging measurements from hygric mammals are rare, and it is not known how these features interact in the environment. Rates of water flux (210 ?? 32 mL d-1) and field metabolic rates (1,488 ?? 486 kJ d-1) were 159% and 265%, respectively, of values predicted by allometric equations for similar-sized herbivores. Mountain beavers can likely meet their water needs through metabolic water production and preformed water in food and thus remain in water balance without access to free water. Arginine-vasopressin levels were strongly correlated with rates of water flux and plasma urea : creatinine ratios, suggesting an important role for this hormone in regulating urinary water loss in mountain beavers. High field metabolic rates may result from cool burrow temperatures that are well below lower critical temperatures measured in previous laboratory studies and suggest that thermoregulation costs may strongly influence field energetics and water flux in semifossorial mammals. ?? 2007 by The University of Chicago. All rights reserved.

  3. Freeze Crystallization Processes: Efficiency by Flexibility

    E-print Network

    Heist, J. A.; Barron, T. S.

    1983-01-01

    the entropy of the separation is less. 3) A heat pump is used in the freeze crystallization process to transfer heat from the freezer to the melter, providing advantages similar to the vapor compression evaporator cycle. Freeze crystallization should...

  4. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...590.536 Freezing operations. (a) Freezing rooms shall be kept clean and free from objectionable odors. (b) Requirements...d) The outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e)...

  5. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...590.536 Freezing operations. (a) Freezing rooms shall be kept clean and free from objectionable odors. (b) Requirements...d) The outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e)...

  6. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...590.536 Freezing operations. (a) Freezing rooms shall be kept clean and free from objectionable odors. (b) Requirements...d) The outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e)...

  7. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...590.536 Freezing operations. (a) Freezing rooms shall be kept clean and free from objectionable odors. (b) Requirements...d) The outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e)...

  8. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...590.536 Freezing operations. (a) Freezing rooms shall be kept clean and free from objectionable odors. (b) Requirements...d) The outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e)...

  9. Status of Chemical Freeze-Out

    E-print Network

    J. Cleymans; H. Oeschler; K. Redlich; S. Wheaton

    2006-07-14

    The status of the energy dependence of the chemical freeze-out temperature and chemical potential obtained in heavy ion collisions is presented. Recent proposals for chemical freeze-out conditions are compared.

  10. The morphology of freeze-dried rubidium chloride powder

    Microsoft Academic Search

    J. K. G. Panitz; J. A. Voigt; F. A. Greulich; M. J. Carr; M. O. Eatough

    1989-01-01

    We have formed powders of a strongly ionic compound, RbCl by freeze-drying. Stock solutions varying from very low concentrations with 4 gm RbCl reagent dissolved in 100 cc water, to saturated solutions with 80 gm reagent in 100 cc water sprayed into isopentane at \\/minus\\/160\\/degree\\/C. The droplet size in the spray was varied from relatively large 4-mm diameter droplets to

  11. Energy and water in Kuwait Part I. A sustainability view point

    Microsoft Academic Search

    M. A. Darwish; F. M. Al-Awadhi; A. M. Darwish

    2008-01-01

    The sustainability of the energy and desalted water in Kuwait is questionable. Kuwait has experienced a very rapid growth in the last five decades by the evolution of oil production and its price increase. The main source of potable water is secured by desalted seawater (about 90–93% desalted water blended with brackish water). The increase of the daily-consumed fresh water

  12. 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.

  13. Critical Watersheds: Climate Change, Tipping Points, and Energy-Water Impacts

    NASA Astrophysics Data System (ADS)

    Middleton, R. S.; Brown, M.; Coon, E.; Linn, R.; McDowell, N. G.; Painter, S. L.; Xu, C.

    2014-12-01

    Climate change, extreme climate events, and climate-induced disturbances will have a substantial and detrimental impact on terrestrial ecosystems. How ecosystems respond to these impacts will, in turn, have a significant effect on the quantity, quality, and timing of water supply for energy security, agriculture, industry, and municipal use. As a community, we lack sufficient quantitative and mechanistic understanding of the complex interplay between climate extremes (e.g., drought, floods), ecosystem dynamics (e.g., vegetation succession), and disruptive events (e.g., wildfire) to assess ecosystem vulnerabilities and to design mitigation strategies that minimize or prevent catastrophic ecosystem impacts. Through a combination of experimental and observational science and modeling, we are developing a unique multi-physics ecohydrologic framework for understanding and quantifying feedbacks between novel climate and extremes, surface and subsurface hydrology, ecosystem dynamics, and disruptive events in critical watersheds. The simulation capability integrates and advances coupled surface-subsurface hydrology from the Advanced Terrestrial Simulator (ATS), dynamic vegetation succession from the Ecosystem Demography (ED) model, and QUICFIRE, a novel wildfire behavior model developed from the FIRETEC platform. These advances are expected to make extensive contributions to the literature and to earth system modeling. The framework is designed to predict, quantify, and mitigate the impacts of climate change on vulnerable watersheds, with a focus on the US Mountain West and the energy-water nexus. This emerging capability is used to identify tipping points in watershed ecosystems, quantify impacts on downstream users, and formally evaluate mitigation efforts including forest (e.g., thinning, prescribed burns) and watershed (e.g., slope stabilization). The framework is being trained, validated, and demonstrated using field observations and remote data collections in the Valles Caldera National Preserve, including pre- and post-wildfire and infestation observations. Ultimately, the framework will be applied to the upper Colorado River basin. Here, we present an overview of the framework development strategy and latest field and modeling results.

  14. Aqueous Chemistry in the Diamond Anvil Cell up to and Beyond the Critical Point of Water

    SciTech Connect

    Bassett, William A.; Chou, I-Ming; Anderson, Alan J.; Mayanovic, Robert (Cornell); (Missouri SU); (SFX); (USGS)

    2008-08-28

    The hydrothermal diamond anvil cell (HDAC) has been developed for the study of fluids and their interactions with other phases. It is capable of pressures up to 10 GPa and temperatures from -190 C to 1200 C. It has found application in studies of equations of state of fluids, reactions between fluids and solids as well as fluids and melts, hydration and dehydration of hydrous solids under P{sub H2O}, fractionation of species between fluids and solids as well as fluids and melts, the effect of P{sub H2O} on melting of silicates, structures of ions and clathrates in solution, preservation of hosts of fluid inclusions at high temperatures, and reactions in clathrates and other organic materials. Visual, spectroscopic, and X-ray methods are used to analyze samples by taking advantage of the exceptional transparency of the diamond anvils. Examples of successful apphcations of the HDAC include the equation of state (EOS) of water, stability of the various stages of hydration of montmorillonite and calcium carbonate, leaching of elements from zircon, the effect of P{sub H2O} on the melting of albite, speciation and structures of Sc, Fe, Cu, Zn, Y, La, Yb, and Br in solution, stability of methane hydrates and Ca(OH){sub 2}, identifying a new H{sub 2}O ice form and sll of methane hydrate. The description of diamond cell configuration, analytical methods, and examples of applications provide evidence of the utility of the technique for many studies of fluids at temperatures and pressures up to and beyond the critical point of water.

  15. Radial interval chance-constrained programming for agricultural non-point source water pollution control under uncertainty

    Microsoft Academic Search

    Q. Tan; G. H. Huang; Y. P. Cai

    2011-01-01

    Inherent uncertainties in agricultural non-point source water pollution control problems cause great difficulties in relevant modeling processes. A radial interval chance-constrained programming (RICCP) approach was developed in this study for supporting source-oriented non-point source pollution control under uncertainty. The proposed RICCP approach could tackle two-layer uncertainty resulting from temporal and spatial variability of many factors and their uncertain interactions. Based

  16. A correlation of water solubility in jet fuels with API gravity: aniline point percent aromatics, and temperature.

    E-print Network

    Byington, Alonzo

    1964-01-01

    A CORRELATION OF WATER SOLUBILITY IN JET FUELS WITH API GRAVITY, ANILINE POINT PERCENT AROMATICS, AND TEMPERATURE A Thesis By ALONZO B YINGTON Submitted to the Graduate College of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE January, 1964 Major Subject: Petroleum Engineering A CORRELATION OF MATER SOLUBILITT IH JET FUELS WITS API GEAVITT, ANILINE POINT, PERCENT ARONATICS, AND TENPERATURE A Thesis By ALOHZO BYIHGTOH Approved...

  17. Critical-point universality in adsorption: The effect of charcoal on a mixture of isobutyric acid and water near the consolute point

    NASA Astrophysics Data System (ADS)

    Giesy, Timothy J.; Chou, Alan S.; McFeeters, Robert L.; Baird, James K.; Barlow, Douglas A.

    2011-06-01

    The mixture of isobutyric acid and water has a consolute point at a temperature of 25.75 °C and mole fraction 0.1148 isobutyric acid. When charcoal is added to this mixture, the concentration of isobutyric acid is reduced by adsorption. We have measured the action of charcoal on solutions of isobutyric acid and water as a function of isobutyric acid mole fraction at temperatures of 25.85 and 32.50 °C. At the higher temperature, the specific adsorption density (y2?/m) satisfies the Freundlich equation (y2?/m)=KX21/n, where y2? is the mass of isobutyric acid adsorbed, m is the mass of charcoal, X2 is the equilibrium mole fraction of isobutyric acid, n is the Freundlich index, and K=K(T) is an amplitude that depends upon the temperature T. At 25.85 °C, a critical endpoint is located at an isobutyric acid mole fraction X2ce=0.09. When compared with the Freundlich equation at this temperature, a plot of the specific adsorption density as a function of X2 in the vicinity of the critical-endpoint composition assumes a shape which is reminiscent of the derivative of a Dirac delta function. Using critical-point scaling theory, we show that this divergent pattern is consistent with the principle of critical point universality.

  18. Combined infrared and freeze-drying.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The drying of the combined infrared (IR) and freeze-drying of food materials has been shown to be very rapid compared to regular freeze drying (FD). The resulting tissue structure of products processed with sequential infrared and freeze drying (SIRFD) tends to have higher crispness than those proce...

  19. TISSUE FREEZING METHODS FOR CRYOSTAT SECTIONING

    E-print Network

    Chisholm, Rex L.

    TISSUE FREEZING METHODS FOR CRYOSTAT SECTIONING Basic Tissue Freezing Methods Preparing Tissue-Roll Plate; Speaker: Donna J. Emge, HT-ASCP, MHPL Manager #12;Preparing Tissue For Freezing Tissue morphological distortions and damage due to: · Tissue drying artifact. · Autolysis - The destruction of tissues

  20. On the representation of immersion and condensation freezing in cloud models using different nucleation schemes

    NASA Astrophysics Data System (ADS)

    Ervens, B.; Feingold, G.

    2012-07-01

    Ice nucleation in clouds is often observed at temperatures >235 K, pointing to heterogeneous freezing as a predominant mechanism. Many models deterministically predict the number concentration of ice particles as a function of temperature and/or supersaturation. Several laboratory experiments, at constant temperature and/or supersaturation, report heterogeneous freezing as a stochastic, time-dependent process that follows classical nucleation theory; this might appear to contradict deterministic models that predict singular freezing behavior. We explore the extent to which the choice of nucleation scheme (deterministic/stochastic, single/multiple contact angles ?) affects the prediction of the fraction of frozen ice nuclei (IN) and cloud evolution for a predetermined maximum IN concentration. A box model with constant temperature and supersaturation is used to mimic published laboratory experiments of immersion freezing of monodisperse (800 nm) kaolinite particles (~243 K), and the fitness of different nucleation schemes. Sensitivity studies show that agreement of all five schemes is restricted to the narrow parameter range (time, temperature, IN diameter) in the original laboratory studies, and that model results diverge for a wider range of conditions. The schemes are implemented in an adiabatic parcel model that includes feedbacks of the formation and growth of drops and ice particles on supersaturation during ascent. Model results for the monodisperse IN population (800 nm) show that these feedbacks limit ice nucleation events, often leading to smaller differences in number concentration of ice particles and ice water content (IWC) between stochastic and deterministic approaches than expected from the box model studies. However, because the different parameterizations of ? distributions and time-dependencies are highly sensitive to IN size, simulations using polydisperse IN result in great differences in predicted ice number concentrations and IWC between the different schemes. The differences in IWC are mostly due to the different temperatures of the onset of freezing in the nucleation schemes that affect the temporal evolution of the ice number concentration. The growth rates of ice particles are not affected by the choice of the nucleation scheme, which leads to very similar particle sizes. Finally, since the choice of nucleation scheme determines the temperature range over which ice nucleation occurs, at habit-prone temperatures (~253 K), there is the potential for variability in the initial inherent growth ratio of ice particles, which can cause amplification or reduction in differences in predicted IWC.

  1. Ultrasonic Measurements of Unconsolidated Saline Sediments During Freeze/Thaw Cycles: The Seismic Properties of Cryopeg Environments

    NASA Astrophysics Data System (ADS)

    Dou, S.; Ajo Franklin, J. B.

    2013-12-01

    Saline permafrost and cryopegs (hypersaline unfrozen layers/zones within permafrost) are widespread in the Arctic coastal area as a result of marine transgression and regression in recent geological history. Owing to the freezing-point depression effect of soluble salts, they contain more unfrozen water than non-saline frozen sediments when subjected to the same permafrost temperatures (e.g., from 0 to -15 °C). Mapping subsurface cryopeg structure remains a challenging geophysical task due to the poor penetration of GPR in highly conductive fluids and related limitations for lower frequency EM techniques. Seismic profiling, particularly surface wave characterization, provides one possible approach to delineate the extent of cryopeg bodies. However, interpretation of such surveys is currently limited by the sparse database of measurements examining the seismic properties of unconsolidated materials saturated with saline fluids at sub-zero temperatures. We present the results of experiments examining seismic velocity in the ultrasonic range for both synthetic and natural permafrost sediments during freeze/thaw cycles; in these experiments, use of a range of brine salinities allows us to evaluate the properties of cryopeg sediments at in-situ conditions, a prerequisite for quantitative interpretation of seismic imaging results. Because of the abundant unfrozen water and less developed inter-granular ice structure, the seismic properties of saline permafrost typically falls between frozen and unfrozen soils. We conducted ultrasonic measurements of a freeze-thaw cycle on 20-30 Ottawa sand (grain size 590-840 ?m) as well as natural mineral soils from the Barrow Environmental Observatory (BEO) saturated with brines of different salinities (0-2.5 M NaCl). For each salinity, seismic properties were measured using the ultrasonic (~1 MHz) pulse-transmission method in the temperature range from 20 to -30 °C. Similar to sediments saturated with low salinity fluids, seismic velocities increase significantly upon freezing in brine-saturated samples due to the formation of ice. However, substantial differences were observed: First, the onset of the velocity increase occurred at temperatures significantly below 0 °C (e.g., as low as -11.8 °C for 2.5 M pore-water salinity); Second, instead of having a stepwise velocity increase (temperature derivative of velocity on the order of 1000 m/s/°C) in the immediate neighborhood of the freezing-point as in non-saline samples, velocities in saline samples exhibit a gradual increase (dv/dT as low as ~70 m/s/°C) in temperatures between the freezing-point and the eutectic-point (~-25 °C) of NaCl solutions. Unusual increases in attenuation were also observed in the vicinity of freezing. Our results indicate that saline permafrost and cryopegs have distinct seismic properties when compared with their non-saline counterparts under the same thermal conditions. Moreover, the very low seismic velocities observed in this laboratory study are consistent with the low-velocity zones at Barrow, Alaska that were previously found through field-scale geophysical investigations.

  2. Preparation of porous scaffolds by using freeze-extraction and freeze-gelation methods

    Microsoft Academic Search

    Ming-Hua Ho; Pei-Yun Kuo; Hsyue-Jen Hsieh; Tzu-Yang Hsien; Lein-Tuan Hou; Juin-Yih Lai; Da-Ming Wang

    2004-01-01

    Freeze-fixation and freeze-gelation methods are presented in this paper which can be used to prepare highly porous scaffolds without using the time and energy consuming freeze-drying process. The porous structure was generated during the freeze of a polymer solution, following which either the solvent was extracted by a non-solvent or the polymer was gelled under the freezing condition; thus, the

  3. The morphology of freeze-dried rubidium chloride powder

    SciTech Connect

    Panitz, J.K.G.; Voigt, J.A.; Greulich, F.A.; Carr, M.J.; Eatough, M.O.

    1989-01-01

    We have formed powders of a strongly ionic compound, RbCl by freeze-drying. Stock solutions varying from very low concentrations with 4 gm RbCl reagent dissolved in 100 cc water, to saturated solutions with 80 gm reagent in 100 cc water sprayed into isopentane at /minus/160/degree/C. The droplet size in the spray was varied from relatively large 4-mm diameter droplets to extremely small droplets in an aerosol spray. It was determined that both the concentration of the stock solution and the droplet size affect the average size and the size distribution of the primary particles formed and the way in which these primary particles are bonded together. Unlike the powders of many less ionic compounds that are produced by freeze-drying, the primary particles in these RbCl powders are crystalline rather than amorphous. Analysis with an x-ray diffractometer with a cold stage indicates that crystallization occurs during the freezing cycle rather than during the sublimation period of the freeze-drying process. 11 refs., 8 figs.

  4. Source of salts in the Waianae part of the Pearl Harbor aquifer near Barbers Point water tunnel, Oahu, Hawaii

    USGS Publications Warehouse

    Eyre, P.R.

    1987-01-01

    The salinity of the water supply of Barbers Point Naval Air Station has increased markedly since 1983. The Naval Air Station obtains its water, about 3 million gal/day, from Barbers Point shaft, a water shaft that taps the Waianae part of the Pearl Harbor aquifer underlying the dry, southeastern flank of the Waianae mountains on the island on Oahu, Hawaii. From 1983 to 1985 the chloride concentration of the water, increased from 220 to 250 mg/L and has remained near that level through 1986. The EPA has established 250 mg/L as the maximum recommended chloride concentration in drinking water because above that level many people can taste the salt. The high chloride concentration in shallow groundwater at all wells in the area indicates that most of the salts in the freshwater lens are contributed by rainfall, sea spray, and irrigation return water. At Barbers Point shaft, pumping may draw a small amount of saltwater from the transition zone and increase the chloride concentration in the pumped water by about 20 mg/L. Salinity of the lens decreases progressively inland in response to recharge from relatively fresher water and in response to an increasing lens thickness with increasing distance from the shoreline. The increase, in 1983, in the chloride concentration of water at the shaft was most probably the result of saltier recharge water reaching the water table, and not the result of increased mixing of underlying saltwater with the freshwater. The chloride concentration of the recharge water has probably increased because, in 1980, the drip method of irrigation began to replace the furrow method on sugarcane fields near the shaft. A mixing-cell model was used to estimate the effect of drip irrigation on the chloride concentration of the groundwater in the vicinity of Barbers Point shaft. The model predicted an increase in chloride concentration of about 50 mg/L. The observed increase was about 30 mg/L and the chloride concentration is presently stable at 245 to 250 mg/L; hence, the chloride concentration is not expected to increase significantly more. (Lantz-PTT)

  5. Differential freezing resistance and photoprotection in C3 and C4 eudicots and grasses

    PubMed Central

    Osborne, Colin P.

    2013-01-01

    Globally, C4 plants dominate hot, open environments, but this general pattern is underpinned by important differences in the biogeography of C4 lineages. In particular, the species richness of C4 Poaceae (grasses) increases strongly with increasing temperature, whereas that of the major C4 eudicot group Chenopodiaceae correlates positively with aridity. Freezing tolerance is a crucial determinant of biogeographical relationships with temperature and is mediated by photodamage and cellular disruption by desiccation, but little is known about differences between C4 families. This study hypothesized that there is a greater risk of freezing damage via these mechanisms in C4 Poaceae than Chenopodiaceae, that freezing protection differs between the taxonomic groups, and that freezing tolerance of species is linked to arid habitat preference. Chlorophyll fluorescence, water relations, and freezing injury were compared in four C3 and six C4 species of Poaceae and Chenopodiaceae from the same Mongolian flora. Contrary to expectations, freezing-induced leaf mortality and photodamage were lower in Poaceae than Chenopodiaceae species, and unrelated to photosynthetic pathway. The freezing resistance of Poaceae species resulted from constitutive protection and cold acclimation and an ability to protect the photosynthetic apparatus from photodamage. Freezing protection was associated with low osmotic potential and low tissue elasticity, and freezing damage was accompanied by electrolyte leakage, consistent with cell-membrane disruption by ice. Both Chenopodiaceae and Poaceae had the potential to develop cold acclimation and withstand freezing during the growing season, which conflicted with the hypothesis. Instead, freezing tolerance was more closely associated with life history and ecological preference in these Mongolian species. PMID:23599273

  6. Comparison of Byproduct Formation in Waters Treated With Chlorine and Iodine: Relevance To Point-Of-Use Treatment

    EPA Science Inventory

    Due to their efficacy in deactivating a range of microbial pathogens, particularly amoebic cysts, iodine-based disinfectants have been a popular option for point-of-use (POU) drinking water disinfection by campers, the military, and rural consumers in developing countries. Recent...

  7. Using an Ice Bath to Approximate the Triple Point of Water When Calibrating Secondary Standard Platinum Resistance Thermometers

    Microsoft Academic Search

    John Zwak

    The Resistance of a Secondary Standard Platinum Resistance Thermometer (SSPRT) at the Triple Point of Water (TPW) is the one of the most important performance criteria for proper monitoring and use of the thermometer. Using a TPW cell to make this measurement can present some challenges related to thermometer configuration and calibration efficiency. By approximating the TPW using a properly

  8. Point Sources of Emerging Contaminants Along the Colorado River Basin: Impact on Water Use and Reuse in the Arid Southwest

    EPA Science Inventory

    Emerging contaminants (ECs) (e.g., pharmaceuticals, illicit drugs, personal care products) have been detected in waters across the United States. The objective of this study was to evaluate point sources of ECs along the Colorado River, from the headwaters in Colorado to the Gulf...

  9. The melting point of ice Ih for common water models calculated from direct coexistence of the solid-liquid interface

    Microsoft Academic Search

    Ramón García Fernández; José L. F. Abascal; Carlos Vega

    2006-01-01

    In this work we present an implementation for the calculation of the melting point of ice Ih from direct coexistence of the solid-liquid interface. We use molecular dynamics simulations of boxes containing liquid water and ice in contact. The implementation is based on the analysis of the evolution of the total energy along NpT simulations at different temperatures. We report

  10. Freeze-Drying of Mononuclear Cells Derived from Umbilical Cord Blood Followed by Colony Formation

    PubMed Central

    Natan, Dity; Nagler, Arnon; Arav, Amir

    2009-01-01

    Background We recently showed that freeze-dried cells stored for 3 years at room temperature can direct embryonic development following cloning. However, viability, as evaluated by membrane integrity of the cells after freeze-drying, was very low; and it was mainly the DNA integrity that was preserved. In the present study, we improved the cells' viability and functionality after freeze-drying. Methodology/Principal Findings We optimized the conditions of directional freezing, i.e. interface velocity and cell concentration, and we added the antioxidant EGCG to the freezing solution. The study was performed on mononuclear cells (MNCs) derived from human umbilical cord blood. After freeze-drying, we tested the viability, number of CD34+-presenting cells and ability of the rehydrated hematopoietic stem cells to differentiate into different blood cells in culture. The viability of the MNCs after freeze-drying and rehydration with pure water was 88%–91%. The total number of CD34+-presenting cells and the number of colonies did not change significantly when evaluated before freezing, after freeze-thawing, and after freeze-drying (5.4×104±4.7, 3.49×104±6 and 6.31×104±12.27 cells, respectively, and 31±25.15, 47±45.8 and 23.44±13.3 colonies, respectively). Conclusions This is the first report of nucleated cells which have been dried and then rehydrated with double-distilled water remaining viable, and of hematopoietic stem cells retaining their ability to differentiate into different blood cells. PMID:19381290

  11. Freezing Poultry for Home Use

    E-print Network

    Davis, Michael

    2006-08-31

    . ? As you work, keep the cutting surface and utensils clean. ? Work quickly and place the poultry in the freezer as quickly as possible. ? Do not let raw poultry juices contaminate ready-to-eat foods. Answering the following questions will help you decide... airtight packaging when freezing poultry. Airtight packaging prevents dehydration and freezer burn. It also helps prevent fat rancidity, oxidation, spoilage, and the growth of disease-causing bacteria. Shrink packages, like the bags in which frozen...

  12. Freeze-drying in novel container system: Characterization of heat and mass transfer in glass syringes.

    PubMed

    Patel, Sajal M; Pikal, Michael J

    2010-07-01

    This study is aimed at characterizing and understanding different modes of heat and mass transfer in glass syringes to develop a robust freeze-drying process. Two different holder systems were used to freeze-dry in syringes: an aluminum (Al) block and a plexiglass holder. The syringe heat transfer coefficient was characterized by a sublimation test using pure water. Mannitol and sucrose (5% w/v) were also freeze-dried, as model systems, in both the assemblies. Dry layer resistance was determined from manometric temperature measurement (MTM) and product temperature was measured using thermocouples, and was also determined from MTM. Further, freeze-drying process was also designed using Smart freeze-dryer to assess its application for freeze-drying in novel container systems. Heat and mass transfer in syringes were compared against the traditional container system (i.e., glass tubing vial). In the Al block, the heat transfer was via three modes: contact conduction, gas conduction, and radiation with gas conduction being the dominant mode of heat transfer. In the plexiglass holder, the heat transfer was mostly via radiation; convection was not involved. Also, MTM/Smart freeze-drying did work reasonably well for freeze-drying in syringes. When compared to tubing vials, product temperature decreases and hence drying time increases in syringes. PMID:20166199

  13. Design of sampling locations for river water quality monitoring considering seasonal variation of point and diffuse pollution loads.

    PubMed

    Varekar, Vikas; Karmakar, Subhankar; Jha, Ramakar; Ghosh, N C

    2015-06-01

    The design of a water quality monitoring network (WQMN) is a complicated decision-making process because each sampling involves high installation, operational, and maintenance costs. Therefore, data with the highest information content should be collected. The effect of seasonal variation in point and diffuse pollution loadings on river water quality may have a significant impact on the optimal selection of sampling locations, but this possible effect has never been addressed in the evaluation and design of monitoring networks. The present study proposes a systematic approach for siting an optimal number and location of river water quality sampling stations based on seasonal or monsoonal variations in both point and diffuse pollution loadings. The proposed approach conceptualizes water quality monitoring as a two-stage process; the first stage of which is to consider all potential water quality sampling sites, selected based on the existing guidelines or frameworks, and the locations of both point and diffuse pollution sources. The monitoring at all sampling sites thus identified should be continued for an adequate period of time to account for the effect of the monsoon season. In the second stage, the monitoring network is then designed separately for monsoon and non-monsoon periods by optimizing the number and locations of sampling sites, using a modified Sanders approach. The impacts of human interventions on the design of the sampling net are quantified geospatially by estimating diffuse pollution loads and verified with land use map. To demonstrate the proposed methodology, the Kali River basin in the western Uttar Pradesh state of India was selected as a study area. The final design suggests consequential pre- and post-monsoonal changes in the location and priority of water quality monitoring stations based on the seasonal variation of point and diffuse pollution loadings. PMID:26009158

  14. Dynamics of Protein Hydration Water

    E-print Network

    M. Wolf; S. Emmert; R. Gulich; P. Lunkenheimer; A. Loidl

    2014-12-08

    We present the frequency- and temperature-dependent dielectric properties of lysozyme solutions in a broad concentration regime, measured at subzero temperatures and compare the results with measurements above the freezing point of water and on hydrated lysozyme powder. Our experiments allow examining the dynamics of unfreezable hydration water in a broad temperature range including the so-called No Man's Land (160 - 235 K). The obtained results prove the bimodality of the hydration shell dynamics and are discussed in the context of the highly-debated fragile-to-strong transition of water.

  15. Investigation of water quality parameters at selected points on the Tennessee River

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The thermal and water quality parameters in the vicinity of widows Creek Steam Generation Plant were investigated. The water quality analysis and temperature profiles are presented for 24 sampling sites.

  16. Ice nucleation activity in various tissues of Rhododendron flower buds: their relevance to extraorgan freezing

    PubMed Central

    Ishikawa, Masaya; Ishikawa, Mikiko; Toyomasu, Takayuki; Aoki, Takayuki; Price, William S.

    2015-01-01

    Wintering flower buds of cold hardy Rhododendron japonicum cooled slowly to subfreezing temperatures are known to undergo extraorgan freezing, whose mechanisms remain obscure. We revisited this material to demonstrate why bud scales freeze first in spite of their lower water content, why florets remain deeply supercooled and how seasonal adaptive responses occur in regard to extraorgan freezing in flower buds. We determined ice nucleation activity (INA) of various flower bud tissues using a test tube-based assay. Irrespective of collection sites, outer and inner bud scales that function as ice sinks in extraorgan freezing had high INA levels whilst florets that remain supercooled and act as a water source lacked INA. The INA level of bud scales was not high in late August when flower bud formation was ending, but increased to reach the highest level in late October just before the first autumnal freeze. The results support the following hypothesis: the high INA in bud scales functions as the subfreezing sensor, ensuring the primary freezing in bud scales at warmer subzero temperatures, which likely allows the migration of floret water to the bud scales and accumulation of icicles within the bud scales. The low INA in the florets helps them remain unfrozen by deep supercooling. The INA in the bud scales was resistant to grinding and autoclaving at 121?C for 15 min, implying the intrinsic nature of the INA rather than of microbial origin, whilst the INA in stem bark was autoclaving-labile. Anti-nucleation activity (ANA) was implicated in the leachate of autoclaved bud scales, which suppresses the INA at millimolar levels of concentration and likely differs from the colligative effects of the solutes. The tissue INA levels likely contribute to the establishment of freezing behaviors by ensuring the order of freezing in the tissues: from the primary freeze to the last tissue remaining unfrozen. PMID:25859249

  17. Effect of freeze-thawing on aggregate stability in a calcareous Mediterranean soil

    NASA Astrophysics Data System (ADS)

    Lozano, Elena; Temporal, Beatriz; Oltra, Ángel; Mataix-Solera, Jorge; Arcenegui, Victoria; García-Orenes, Fuensanta

    2013-04-01

    Soil freezing has been reported as both beneficial and detrimental for soil structure depending on various factors (Dagesse, 2011), but the subsequent thawing process has not been adequately investigated as a factor in determining the net effect of freezing and thawing. In this study changes in soil aggregate stability (AS) were studied under different moisture and speed of thawing conditions in a laboratory experiment. Conditions favoring sublimation and commonly experienced during the winter include bare soil surfaces and synoptic meteorological conditions of clear skies, low humidity, and moderate winds. Aggregate stability measured may therefore reflect the effects of drying of the soil aggregates via the freezing process and the resulting water content distribution following thawing. The soil used is from an agricultural area located in Sierra de Enguera (Valencia, E Spain). Soil samples were collected in February 2012 from the first 2.5 cm depth of A horizon. We also studied the effect of a mulch cover in buffering soil temperature during 2 months under field conditions using thermocouples and data-loggers. Soil samples at two initial water contents (10% and 40%) were subjected to different treatments, including not frozen (control), freeze-thaw (freezing at -4 °C for 3 h and thawing at room temperature for 24 h) and freeze-drying (freezing at -4 for 3h and thawing at 60 °C for 3 h in a forced air oven). We measured the possible soil disruption of soil aggregates quantifying the soil mass in the fractions 2-0.25 mm and

  18. Electrochemical Surface Potential due to Classical Point Charge Models Drives Anion Adsorption to the Air-Water Interface

    SciTech Connect

    Baer, Marcel D.; Stern, Abraham C.; Levin, Yan; Tobias, Douglas J.; Mundy, Christopher J.

    2012-06-07

    Herein, we present research that suggests that the underlying physics that drive simple empirical models of anions (e.g. point charge, no polarization) to the air-water interface, with water described by SPC/E, or related partial charge models is different than when both ions and water are modeled with quantum mechanical based interactions. Specifically, we will show that the driving force of ions to the air-water interface for point charge models results from both cavitation and the negative electrochemical surface potential. We will demonstrate that we can fully characterize the role of the free energy due to the electrochemical surface potential computed from simple empirical models and its role in ionic adsorption within the context of dielectric continuum theory (DCT). Our research suggests that a significant part of the electrochemical surface potential in empirical models appears to be an artifact of the failure of point charge models in the vicinity of a broken symmetry. This work was supported by the U.S. Department of Energy‘s (DOE) Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the Department of Energy by Battelle.

  19. Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

    SciTech Connect

    Stinson, Jake L., E-mail: j.stinson@ucl.ac.uk; Ford, Ian J. [Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT (United Kingdom)] [Department of Physics and Astronomy and London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT (United Kingdom); Kathmann, Shawn M. [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)] [Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

    2014-01-14

    The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei, and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nuclei have a classical nature, which is questionable for some systems. The importance of zero-point motion (also known as quantum nuclear dynamics) in modelling small clusters of sulphuric acid and water is tested here using the path integral molecular dynamics method at the density functional level of theory. The general effect of zero-point motion is to distort the mean structure slightly, and to promote the extent of proton transfer with respect to classical behaviour. In a particular configuration of one sulphuric acid molecule with three waters, the range of positions explored by a proton between a sulphuric acid and a water molecule at 300 K (a broad range in contrast to the confinement suggested by geometry optimisation at 0 K) is clearly affected by the inclusion of zero point motion, and similar effects are observed for other configurations.

  20. Cryo-scanning electron microscopic study on freezing behavior of xylem ray parenchyma cells in hardwood species

    Microsoft Academic Search

    S Fujikawa; K Kuroda

    2000-01-01

    Differential thermal analysis (DTA) has indicated that xylem ray parenchyma cells (XRPCs) of hardwood species adapt to freezing of apoplastic water either by deep supercooling or by extracellular freezing, depending upon the species. DTA studies indicated that moderately cold hardy hardwood species exhibiting deep supercooling in the XRPCs were limited in latitudinal distribution within the ?40°C isotherm, while very hardy

  1. Encapsulation of black carrot juice using spray and freeze drying.

    PubMed

    Murali, S; Kar, Abhijit; Mohapatra, Debabandya; Kalia, Pritam

    2014-11-01

    Black carrot juice extracted using pectinase enzyme was encapsulated in three different carrier materials (maltodextrin 20DE, gum arabic and tapioca starch) using spray drying at four inlet temperatures (150, 175, 200 and 225??) and freeze drying at a constant temperature of?-?53?? and vacuum of 0.22-0.11?mbar with the constant feed mixture. The products were analyzed for total anthocyanin content, antioxidant activity, water solubility index, encapsulation efficiency and total colour change. For both the drying methods followed in this study, maltodextrin 20DE as the carrier material has proven to be better in retaining maximum anthocyanin and antioxidant activity compared to gum arabic and tapioca starch. The best spray dried product, was obtained at 150??. The most acceptable was the freeze dried product with maximum anthocyanin content, antioxidant activity, water solubility index, encapsulation efficiency and colour change. PMID:25367889

  2. Point-of-use chlorination of turbid water: results from a field study in Tanzania.

    PubMed

    Mohamed, Hussein; Brown, Joe; Njee, Robert M; Clasen, Thomas; Malebo, Hamisi M; Mbuligwe, Steven

    2015-06-01

    Household-based chlorine disinfection is widely effective against waterborne bacteria and viruses, and may be among the most inexpensive and accessible options for household water treatment. The microbiological effectiveness of chlorine is limited, however, by turbidity. In Tanzania, there are no guidelines on water chlorination at household level, and limited data on whether dosing guidelines for higher turbidity waters are sufficient to produce potable water. This study was designed to assess the effectiveness of chlorination across a range of turbidities found in rural water sources, following local dosing guidelines that recommend a 'double dose' for water that is visibly turbid. We chlorinated water from 43 sources representing a range of turbidities using two locally available chlorine-based disinfectants: WaterGuard and Aquatabs. We determined free available chlorine at 30 min and 24 h contact time. Our data suggest that water chlorination with WaterGuard or Aquatabs can be effective using both single and double doses up to 20 nephelometric turbidity units (NTU), or using a double dose of Aquatabs up to 100 NTU, but neither was effective at turbidities greater than 100 NTU. PMID:26042985

  3. Computational analysis of fluid dynamics in pharmaceutical freeze-drying.

    PubMed

    Alexeenko, Alina A; Ganguly, Arnab; Nail, Steven L

    2009-09-01

    Analysis of water vapor flows encountered in pharmaceutical freeze-drying systems, laboratory-scale and industrial, is presented based on the computational fluid dynamics (CFD) techniques. The flows under continuum gas conditions are analyzed using the solution of the Navier-Stokes equations whereas the rarefied flow solutions are obtained by the direct simulation Monte Carlo (DSMC) method for the Boltzmann equation. Examples of application of CFD techniques to laboratory-scale and industrial scale freeze-drying processes are discussed with an emphasis on the utility of CFD for improvement of design and experimental characterization of pharmaceutical freeze-drying hardware and processes. The current article presents a two-dimensional simulation of a laboratory scale dryer with an emphasis on the importance of drying conditions and hardware design on process control and a three-dimensional simulation of an industrial dryer containing a comparison of the obtained results with analytical viscous flow solutions. It was found that the presence of clean in place (CIP)/sterilize in place (SIP) piping in the duct lead to significant changes in the flow field characteristics. The simulation results for vapor flow rates in an industrial freeze-dryer have been compared to tunable diode laser absorption spectroscopy (TDLAS) and gravimetric measurements. PMID:19569225

  4. Additional weight load increases freezing of gait episodes in Parkinson's disease; an experimental study.

    PubMed

    Mensink, Senja H G; Nonnekes, Jorik; van Bon, Geert; Snijders, Anke H; Duysens, Jacques; Weerdesteyn, Vivian; Bloem, Bastiaan R; Oude Nijhuis, Lars B

    2014-05-01

    Freezing of gait is an episodic gait disorder,characterized by the inability to generate effective forward stepping movements. The pathophysiology underlying freezing of gait remains insufficiently understood, and this hampers the development of better treatment strategies.Preliminary evidence suggests that impaired force control during walking may contribute to freezing episodes, with difficulty to unload the swing leg and initiate the swing phase. Here, we used external loading to manipulate force control and to investigate its influence on freezing of gait.Twelve Parkinson's disease patients with freezing of gait performed three contrasting tasks: (1) loaded gait while wearing a belt fortified with lead weights; (2) weight supported gait using a parachute harness connected to a rigid metal cable running above the gait trajectory; and (3)normal gait. Gait tasks were used to provoke freezing episodes, including rapid 360° turns. Freezing episodes were quantified using blinded, videotaped clinical assessment. Furthermore, ground reaction forces and body kinematics were recorded. Loading significantly increased the mean number of freezing episodes per trial compared to the normal gait condition (P<0.05), but the effect of weight support was not consistent. Loading particularly increased the number of freezing episodes during rapid short steps. Step length was significantly smaller during loaded gait compared to normal gait (P<0.05), but changes in anticipatory postural adjustments were not different.Our results may point to impaired force control playing a key role in freezing of gait. Future studies should further investigate the mechanism, i.e., the contribution of deficient load feedback, and evaluate which forms of weight support might offer treatment opportunities. PMID:24658705

  5. Mechanisms of deterioration of nutrients. [freeze drying methods for space flight food

    NASA Technical Reports Server (NTRS)

    Karel, M.; Flink, J. M.

    1974-01-01

    Methods are reported by which freeze dried foods of improved quality will be produced. The applicability of theories of flavor retention has been demonstrated for a number of food polymers, both proteins and polysacchardies. Studies on the formation of structures during freeze drying have been continued for emulsified systems. Deterioration of organoleptic quality of freeze dried foods due to high temperature heating has been evaluated and improved procedures developed. The influence of water activity and high temperature on retention of model flavor materials and browning deterioration has been evaluated for model systems and food materials.

  6. [Use of two-points-short-term free chlorine plus chloramines disinfection process in conventional treatments of water supply].

    PubMed

    Liu, Jing; Chen, Chao; Zhang, Xiao-jian; Wang, Yang

    2008-12-01

    Two-points-short-term free chlorine plus chloramines disinfection process was used in conventional treatments of water supply. The process is adding chlorine at the start of filtration and clear well respectively, and then after a few minutes chlorine disinfection in clear well adding ammonia to change the chlorine to chloramines. The point of chlorine dosing move up to the filtration process can decrease disinfection by-product yield and control bio-film growth in filtration process. Compared with adding equal quantity chlorine once, this process reduced 51.6% of THMs and 46.7% of HAAs. HPC result also showed advantage in microorganism controlling. PMID:19256369

  7. A Water Quality Monitoring Network Design Methodology for the Selection of Critical Sampling Points: Part I

    Microsoft Academic Search

    R. O. Strobl; P. D. Robillard; R. D. Shannon; R. L. Day; A. J. McDonnell

    2006-01-01

    The principal instrument to temporally and spatially manage water resources is a water quality monitoring network. However,\\u000a to date in most cases, there is a clear absence of a concise strategy or methodology for designing monitoring networks, especially\\u000a when deciding upon the placement of sampling stations. Since water quality monitoring networks can be quite costly, it is\\u000a very important to

  8. DEHYDRATION OF GREEN PEAS UNDER ATMOSPHERIC FREEZE-DRYING CONDITIONS

    Microsoft Academic Search

    Odilio Alves-Filho; Pablo García-Pascual; Trygve M. Eikevik; Ingvald Strømmen

    The drying of green peas was studied in a fluidized bed heat pump dryer under atmospheric freeze-drying conditions and at 25ºC, operating either at a constant or on a combination of temperatures. Three types of green peas and two bed heights were used in the drying trials. In addition to the drying kinetics, different product parameters (color, water activity, floatability,

  9. Anhydrobiosis and freezing-tolerance: adaptations that facilitate the establishment of Panagrolaimus nematodes in polar habitats.

    PubMed

    McGill, Lorraine M; Shannon, Adam J; Pisani, Davide; Félix, Marie-Anne; Ramløv, Hans; Dix, Ilona; Wharton, David A; Burnell, Ann M

    2015-01-01

    Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent "ecological fitting" of freezing-tolerant anhydrobiotic propagules to the respective abiotic conditions in Ross Island and Surtsey. PMID:25747673

  10. The solubility of the noble gases He, Ne, Ar, Kr, and Xe in water up to the critical point

    USGS Publications Warehouse

    Potter, R.W., II; Clynne, M.A.

    1978-01-01

    The solubility of the noble gases Ar, He, Ne, Kr, and Xe in pure water was measured from 298 to 561??K. These data in turn were extrapolated to the critical point of water, thus providing a complete set of Henry's law constants from 274 to 647??K when combined with the existing literature data. Equations describing the behavior of the Henry's law constants over this temperature range are also given. The data do not confirm extrapolations of empirical correlations based on low-temperature solubility data. ?? 1978 Plenum Publishing Corporation.

  11. Freeze-Drying Characteristics of Tropical Fruits

    Microsoft Academic Search

    Ana M. Silveira; José T. Freire

    2006-01-01

    The objective of this work was to experimentally determine physical properties such as apparent densities, real densities, and porosity of freeze-dried tropical fruits pulps such as pineapple, Barbados cherry, guava, papaya, and mango, and to carry out nutritional analysis of vitamin C, calcium, and phosphorus in the freeze-dried and in natura pulps. The freeze-dried pulps presented low apparent density and

  12. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    EPA Science Inventory

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  13. Ions in water: Characterizing the forces that control chemical processes and biological structure

    Microsoft Academic Search

    Kim D. Collins; George W. Neilson; John E. Enderby

    2007-01-01

    The continuum electrostatics model of Debye and Hückel [P. Debye and E. Hückel, On the theory of electrolytes. I. Freezing point depression and related phenomena., Phys. Z. 24 (1923) 185–206.] and its successors utilize a macroscopic dielectric constant and assume that all interactions involving ions are strictly electrostatic, implying that simple ions in water generate electric fields strong enough to

  14. Freeze Enhanced Halate Halide Reactions

    NASA Astrophysics Data System (ADS)

    Newberg, J. T.; Weaver, K.; Broderick, A.

    2014-12-01

    Relatively little is known about halate ion species (XO3-; X = I, Br, Cl) in atmospheric condensed phases. It was initial thought that iodate was a terminal stable species upon iodide oxidation. However, it is becoming increasingly recognized that reactions involving iodate can lead to reactive iodine, and this chemistry is accelerated under acidic conditions. The environmental concentrations and chemistry of bromate and chlorate are largely unexplored in environmental ices. We present results from a series of aqueous phase halate ion reactions with halides under acidic conditions, showing that the kinetics are strongly enhanced upon freezing. The products of these reactions are reactive halogens, which have important implications to marine boundary layer chemistry.

  15. X-ray microanalysis of freeze-dried and frozen-hydrated cryosections

    Microsoft Academic Search

    Karl Zierold

    1988-01-01

    The elemental composition and the ultrastructure of biological cells were studied by scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray microanalysis. The preparation technique involves cryofixation, cryoultramicrotomy, cryotransfer, and freeze-drying of samples. Freeze-dried cryosections 100-nm thick appeared to be appropriate for measuring the distribution of diffusible elements and water in different compartments of the cells. The lateral analytical

  16. POINT-OF-ENTRY DRINKING WATER TREATMENT SYSTEMS FOR SUPERFUND APPLICATIONS

    EPA Science Inventory

    The U.S. Environmental Protection AGency (EPA) and State Superfund agencies need a technical assistance manualto assist their personnel in the selection of an effective drinking water treatment system for aindividualhouseholds in areas whre the drinking water has been adversely a...

  17. The North Cape oil spill: hydrocarbons in Rhode Island coastal waters and Point Judith Pond

    Microsoft Academic Search

    C. M. Reddy; J. G. Quinn

    2001-01-01

    On 19 January 1996, the North Cape oil barge ran aground near Moonstone Beach, RI, and spilled over 2700 metric tons of No. 2 fuel oil during a severe winter storm. High winds and rough seas drove the oil into the water column, and the oil spread throughout Block Island Sound and into several coastal salt ponds. Over 50 water

  18. Critical risk points of nanofiltration and reverse osmosis processes in water recycling applications

    Microsoft Academic Search

    Long D. Nghiem; Andrea I. Schäfer

    2006-01-01

    NF\\/RO membrane filtration processes have been recognized as an important technology to facilitate water recycling. Those processes are well-proven technologies, which can be used to remove a wide range of contaminants including trace contaminants that are of particular concern in water recycling. However, risk implications in association with brine or concentrate and membrane cleaning wastewater disposal have to date not

  19. Biopolymer-reinforced synthetic granular nanocomposites for affordable point-of-use water purification

    PubMed Central

    Sankar, Mohan Udhaya; Aigal, Sahaja; Maliyekkal, Shihabudheen M.; Chaudhary, Amrita; Anshup; Kumar, Avula Anil; Chaudhari, Kamalesh; Pradeep, Thalappil

    2013-01-01

    Creation of affordable materials for constant release of silver ions in water is one of the most promising ways to provide microbially safe drinking water for all. Combining the capacity of diverse nanocomposites to scavenge toxic species such as arsenic, lead, and other contaminants along with the above capability can result in affordable, all-inclusive drinking water purifiers that can function without electricity. The critical problem in achieving this is the synthesis of stable materials that can release silver ions continuously in the presence of complex species usually present in drinking water that deposit and cause scaling on nanomaterial surfaces. Here we show that such constant release materials can be synthesized in a simple and effective fashion in water itself without the use of electrical power. The nanocomposite exhibits river sand-like properties, such as higher shear strength in loose and wet forms. These materials have been used to develop an affordable water purifier to deliver clean drinking water at US $2.5/y per family. The ability to prepare nanostructured compositions at near ambient temperature has wide relevance for adsorption-based water purification. PMID:23650396

  20. Freeze out in narrow and wide layers

    E-print Network

    V. K. Magas; L. P. Csernai; E. Molnar

    2006-01-19

    The freeze out of particles from a layer of finite thickness is discussed in a phenomenological kinetic model. The proposed model, based on the Modified Boltzman Transport Equation, is Lorentz invariant and can be applied equally well for the freeze out layers with space-like and time-like normal vectors. It leads to non-equilibrated post freeze out distributions. The dependence of the resulting distribution on the thickness of the layer is presented and discussed for a space-like freeze out scenario.

  1. [Determination of trace cobalt in water samples by graphite furnace atomic absorption spectrometry after cloud point].

    PubMed

    Zhang, Yuan; Luo, Wen-hong; Li, Hui

    2005-04-01

    In buffer solution of citric acid monohydrate-disodium hydrogen phosphate at pH 5-7.5, cobalt water samples were chelated by 1-(2-pyridylazo)-2-naphthol (PAN) to form Co-PAN. After water-bath at 66 degrees C for two hours, Co-PAN is extracted into Triton X-100 nonionic surfactant phase and separated from bulk water. Extracted cobalt content was measured by graphite furnace atomic absorption spectrometry. The surfactant phase separated was treated with 0.5% HNO3-0.1% Pd(NO3)2 to remove background interference at 1200 degrees C temperature. The pre-concentration of cobalt in water samples permitted the detection of 0.003 microg x L(-1) (10sigma) with the enhancement factor of 100. The recoveries were 90.5%-106%. The proposed method was applied to the determination of cobalt in water samples and satisfactory results were obtained. PMID:16097690

  2. QSPR models of boiling point, octanol–water partition coefficient and retention time index of polycyclic aromatic hydrocarbons

    Microsoft Academic Search

    Fabiana Alves de Lima Ribeiro; Márcia Miguel Castro Ferreira

    2003-01-01

    A Quantitative Structure–Property Relationship (QSPR) analysis and study of polycyclic aromatic hydrocarbons (PAHs) is presented. Three physicochemical properties related to their environmental impact are studied: boiling point (bp), octanol–water partition coefficient (logKow) and retention time index (RI) for reversed-phase liquid chromatography analysis. The geometry of all PAHs were optimized by the semi-empirical method AM1 and used to calculate thermodynamic, electronic,

  3. The use of bushings with triple point of water cells: towards breaking the 50 µK barrier

    Microsoft Academic Search

    P. P. M. Steur; R. Dematteis

    2008-01-01

    Instabilities of the order of 50 µK or higher have been observed in water triple point cells with a thermometer well of 12 mm to 13.6 mm diameter during measurements at the INRiM in the framework of the Euromet.T-K7 comparison. In the course of many follow-up measurements, extending over more than one year, these anomalies have been investigated and a

  4. Precise Determination of Hydrostatic Pressure Correction Coefficient of Triple Point Cell of Water using Cryogenic Current Comparator Bridge

    Microsoft Academic Search

    Masakazu Nakanishi; Hirohisa Sakurai

    2005-01-01

    Applying a cryogenic current comparator bridge to resistance thermometry, the temperature distributions along the thermometer wells of two triple point cells of water are precisely measured using a standard platinum resistance thermometer with low measuring currents of about 0.1 mA. The average hydrostatic pressure coefficient of the two cells calculated from the temperature distributions is -0.854(38) mK\\/m. This value agrees

  5. Acoustic Resonator Experiments at the Triple Point of Water: First Results for the Boltzmann Constant and Remaining Challenges

    Microsoft Academic Search

    Gavin Sutton; Robin Underwood; Laurent Pitre; Michael de Podesta; Staf Valkiers

    2010-01-01

    We report on two sets of isothermal acoustic measurements made with argon close to the triple point of water using a 50 mm\\u000a radius, thin-walled, diamond-turned quasisphere. Our two isotherms yielded values for the Boltzmann constant, k\\u000a B, which differ by 0.9 parts in 106, and have an average value of k\\u000a B = (1.380 649 6 ± 0.000 004 3) ×

  6. Monte Carlo calculations of low-energy electron dose-point-kernels in water using different stopping power approximations

    Microsoft Academic Search

    Christos Bousis; Dimitris Emfietzoglou; Panagiotis Hadjidoukas; Hooshang Nikjoo; Anand Pathak

    2011-01-01

    The spatial distribution of absorbed energy in irradiated matter can be conveniently described by dose-point-kernel (DPK) distributions that characterize the average energy deposition around single charged-particle tracks during their slowing down process. In the present work, electron DPKs in liquid water in the energy range from 100eV to 10keV are presented based on Monte Carlo simulation of electron transport in

  7. Effects of Micro/Nano-Scale Surface Characteristics on the Leidenfrost Point Temperature of Water

    E-print Network

    Hu, Lin-Wen

    In recent film boiling heat transfer studies with nanofluids, it was reported that deposition of nanoparticles on a surface significantly increases the nominal minimum heat flux (MHF) or Leidenfrost Point (LFP) temperature, ...

  8. Swash-aquifer interaction in the vicinity of the water table exit point on a sandy beach Research Report No R863

    Microsoft Academic Search

    Nick Cartwright; Tom E. Baldock; Peter Nielsen; Dong-Sheng Jeng; L. Tao

    The coupling of sandy beach aquifers with the swash zone in the vicinity of the water table exit point is investigated through simultaneous measurements of the instantaneous shoreline (swash front) location, pore pressures and the water table exit point. The field observations reveal new insights into swash-aquifer coupling not previously gleaned from measurements of pore pressure only. In particular, for

  9. Phys1101, Spring 2010 Temperature Scales

    E-print Network

    Boyd, Sylke

    points 0 C water freezes 100 C water boils 0 F salt solution freezes 96 F body temperature 0 K lowest, BE Absolute zero Lowest freezing point of salt solution Freezing point of water Room temperature Boiling point

  10. Accuracy of tropospheric and stratospheric water vapor measurements by the cryogenic frost point hygrometer: Instrumental details and observations

    NASA Astrophysics Data System (ADS)

    VöMel, H.; David, D. E.; Smith, K.

    2007-04-01

    The cryogenic frost point hygrometer (CFH), currently built at the University of Colorado, is a new balloon borne hygrometer, which is capable of continuously measuring water vapor between the surface and the middle stratosphere. The design is loosely based on the old NOAA/CMDL frost point hygrometer, with improved accuracy and a number of significant new features that overcome some limitations of the older instrument. The measurement uncertainty of the new instrument depends on altitude and ranges between less than 4% in the tropical lower troposphere to no more than 10% in the middle stratosphere at 28 km. In the tropopause region the uncertainty is less than 9%. This instrument is used routinely at several sites for validation of satellite measurements and process studies in the upper troposphere and lower stratosphere region. It has proved to be particularly well suited for dehydration observations in the tropical upper troposphere, because the effects of cloud contamination have been significantly reduced. Results of this instrument are compared with the old NOAA/CMDL hygrometer, the Russian Fluorescent Lyman Alpha Stratospheric Hygrometer, the Vaisala RS92, the AURA/MLS satellite instrument, a cloud lidar, the NOAA/CSD frost point hygrometer and the Harvard Lyman-alpha hygrometer, both of the later instruments flown on board the NASA WB-57F high-altitude research aircraft. These comparisons demonstrate the level of accuracy of tropospheric and stratospheric water vapor measurements made by this instrument and point to areas where more research and development are needed.

  11. Flocculant-disinfectant point-of-use water treatment for reducing arsenic exposure in rural Bangladesh.

    PubMed

    Norton, Dawn M; Rahman, Mahfuz; Shane, Andi L; Hossain, Zahid; Kulick, Roy M; Bhuiyan, Mahbubul I; Wahed, M Abdul; Yunus, Mohammad; Islam, M Siraj; Breiman, Robert F; Henderson, Alden; Keswick, Bruce H; Luby, Stephen P

    2009-02-01

    We introduced flocculant-disinfectant water treatment for 12 weeks in 103 households in Bangladesh to assess if drinking water would be chemically and microbiologically improved and the body burden of arsenic reduced. The median concentration of arsenic in tubewell water decreased by 88% after introduction of the flocculant-disinfectant from 136 microg/l at baseline to 16 (p < 0.001). The median concentration of total urinary arsenic decreased 42% from 385 microg/g creatinine at baseline to 225 microg/g creatinine after intervention (p < 0.001). Among 206 post-intervention drinking water samples that were reportedly treated on the date the sample was collected, 99 (48%) lacked residual free chlorine and 100 (49%) were contaminated with thermotolerant coliforms. The flocculant-disinfectant markedly reduced arsenic in drinking water, but treated drinking water was frequently contaminated with fecal organisms. The lesser reduction in urinary arsenic compared to water arsenic and the health consequences of this reduction require further research. PMID:19241244

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

    E-print Network

    Peter O. Fedichev; Leonid I. Menshikov

    2012-01-30

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

  13. Diarrhoea prevention in Bolivia through point-of-use water treatment and safe storage: a promising new strategy.

    PubMed Central

    Quick, R. E.; Venczel, L. V.; Mintz, E. D.; Soleto, L.; Aparicio, J.; Gironaz, M.; Hutwagner, L.; Greene, K.; Bopp, C.; Maloney, K.; Chavez, D.; Sobsey, M.; Tauxe, R. V.

    1999-01-01

    A novel water quality intervention that consists of point-of-use water disinfection, safe storage and community education was field tested in Bolivia. A total of 127 households in two periurban communities were randomized into intervention and control groups, surveyed and the intervention was distributed. Monthly water quality testing and weekly diarrhoea surveillance were conducted. Over a 5-month period, intervention households had 44% fewer diarrhoea episodes than control households (P = 0.002). Infants < 1 year old (P = 0.05) and children 5-14 years old (P = 0.01) in intervention households had significantly less diarrhoea than control children. Campylobacter was less commonly isolated from intervention than control patients (P = 0.02). Stored water in intervention households was less contaminated with Escherichia coli than stored water in control households (P < 0.0001). Intervention households exhibited less E. coli contamination of stored water and less diarrhoea than control households. This promising new strategy may have broad applicability for waterborne disease prevention. PMID:10098789

  14. Alternative Electrode Materials and Ceramic Filter Minimize Disinfection Byproducts in Point-of-Use Electrochemical Water Treatment.

    PubMed

    Yoon, Yeojoon; Jung, Youmi; Kwon, Minhwan; Cho, Eunha; Kang, Joon-Wun

    2013-12-01

    Effects of various electrodes and prefiltration to minimize disinfection byproducts (DBPs) in electrochemical water disinfection was evaluated. The target microorganism, Escherichia coli O157:H7, was effectively inactivated even applying a solar-charged storage battery for the electrolysis process. Extent of microbial inactivation decreased with lower water temperature and higher pH in the free chlorine disinfection system. The RuO2/Ti electrode was most efficient because it produced the lowest concentration of chlorate and the highest generation of free chlorine. Prefiltration using a ceramic filter inhibited formation of halogenated DBPs because it removed precursors of DBPs. For safe point-of-use water treatment, the use of a hybrid prefiltration stage with the electrolysis system is strongly recommended to reduce risks from DBPs. The system is particularly suited to use in developing regions. PMID:24381482

  15. A spatial model to aggregate point-source and nonpoint-source water-quality data for large areas

    USGS Publications Warehouse

    White, D.A.; Smith, R.A.; Price, C.V.; Alexander, R.B.; Robinson, K.W.

    1992-01-01

    More objective and consistent methods are needed to assess water quality for large areas. A spatial model, one that capitalizes on the topologic relationships among spatial entities, to aggregate pollution sources from upstream drainage areas is described that can be implemented on land surfaces having heterogeneous water-pollution effects. An infrastructure of stream networks and drainage basins, derived from 1:250,000-scale digital-elevation models, define the hydrologic system in this spatial model. The spatial relationships between point- and nonpoint pollution sources and measurement locations are referenced to the hydrologic infrastructure with the aid of a geographic information system. A maximum-branching algorithm has been developed to simulate the effects of distance from a pollutant source to an arbitrary downstream location, a function traditionally employed in deterministic water quality models. ?? 1992.

  16. COMPARISON OF MULTIPLE POINT AND COMPOSITE SAMPLING FOR THE PURPOSE OF MONITORING BATHING WATER QUALITY

    EPA Science Inventory

    The USEPA Beaches Environmental Assessment and Coastal Health Act (BEACH Act) requires states to develop monitoring and notification programs for recreational waters using approved bacterial indicators. Implementation of an appropriate monitoring program can, under some circumsta...

  17. Critical risk points of nanofiltration and reverse osmosis processes in water recycling applications 

    E-print Network

    Nghiem, Long D.; Schäfer, Andrea

    2006-01-01

    NF/RO membrane filtration processes have been recognized as an important technology to facilitate water recycling. Those processes are well-proven technologies, which can be used to remove a wide range of contaminants ...

  18. Provision of watering points in the Australian arid zone: a review of effects on biota

    Microsoft Academic Search

    Craig D. James; Jill Landsberg; Stephen R. Morton

    1999-01-01

    In this paper we review the effects of the provision of artificial sources of water on native flora and fauna in arid and semi-arid zones, with emphasis on Australia but drawing on information from other countries where possible. The effects of artificial sources of water are profound and are a rarely-cited aspect of change in arid and semi-arid zone rangelands.

  19. Dynamic Crossover Phenomenon in Confined Supercooled Water and Its Relation to the Existence of a Liquid-Liquid Critical Point in Water

    NASA Astrophysics Data System (ADS)

    Chen, Sow-Hsin; Mallamace, F.; Liu, L.; Liu, D. Z.; Chu, X. Q.; Zhang, Y.; Kim, C.; Faraone, A.; Mou, C.-Y.; Fratini, E.; Baglioni, P.; Kolesnikov, A. I.; Garcia-Sakai, V.

    2008-02-01

    We have observed a Fragile-to-Strong Dynamic Crossover (FSC) phenomenon of the ?-relaxation time and self-diffusion constant in confined supercooled water. The ?-relaxation time is measured by Quasielastic Neutron Scattering (QENS) experiments and the self-diffusion constant by Nuclear Magnetic Resonance (NMR) experiments. Water is confined in 1-d geometry in cylindrical pores of nanoscale silica materials, MCM-41-S and in Double-Wall Carbon Nanotubes (DWNT). The crossover phenomenon can also be observed from appearance of a Boson peak in Incoherent Inelastic Neutron Scattering experiments. We observe a pronounced violation of the Stokes-Einstein Relation at and below the crossover temperature at ambient pressure. Upon applying pressure to the confined water, the crossover temperature is shown to track closely the Widom line emanating from the existence of a liquid-liquid critical point in an unattainable deeply supercooled state of bulk water. Relation of the dynamic crossover phenomenon to the existence of a density minimum in supercooled confined water is discussed. Finally, we discuss a role of the FSC of the hydration water in a biopolymer that controls the biofunctionality of the biopolymer.

  20. Treatment of textile wastewaters using Eutectic Freeze Crystallization.

    PubMed

    Randall, D G; Zinn, C; Lewis, A E

    2014-01-01

    A water treatment process needs to recover both water and other useful products if the process is to be viewed as being financially and environmentally sustainable. Eutectic Freeze Crystallization (EFC) is one such sustainable water treatment process that is able to produce both pure ice (water) and pure salt(s) by operating at a specific temperature. The use of EFC for the treatment of water is particularly useful in the textile industry because ice crystallization excludes all impurities from the recovered water, including dyes. Also, EFC can produce various salts with the intention of reusing these salts in the process. This study investigated the feasibility of EFC as a treatment method for textile industry wastewaters. The results showed that EFC can be used to convert 95% of the wastewater stream to pure ice (98% purity) and sodium sulfate. PMID:25116506

  1. Relationship of Product Structure, Sorption Characteristics, and Freezing Point of Atmospheric Freeze-Dried Foods

    Microsoft Academic Search

    Ingrid Camilla Claussen; Ingvald Strømmen; Anne Karin Torstveit Hemmingsen; Turid Rustad

    2007-01-01

    Drying is an important unit operation in processing of foods with a long shelf life. The drying process influences product properties and quality; the products may shrink, break, or undergo rheological, physical, and biochemical changes. Important parameters responsible for product quality changes during drying are temperature, relative humidity, and residence time. Studies of thermal and mass transfer properties during drying

  2. Is it possible to reconstruct the freeze-out duration of heavy-ion collisions using tomography?

    E-print Network

    David A. Brown

    2000-03-10

    We investigate what conditions allow us to extract the relative distribution of freeze-out space and time points in an arbitrary reference frame using tomography and source imaging. The source function may be extracted from the two-particle correlation function measured in heavy-ion collisions using imaging techniques. This imaged source function is related to the relative distribution of freeze-out space and time points through a generalization of the Radon transform found in tomography. Using tomography, the imaged source function may be converted into the relative freeze-out distribution in the frame of interest. We describe how the tomography may be performed in practice.

  3. Simulation and field monitoring of moisture in alpine rock walls during freeze-thaw events

    NASA Astrophysics Data System (ADS)

    Rode, Matthias; Sass, Oliver

    2013-04-01

    Detachment of rock fragments from alpine rockwalls is mainly assigned to frost weathering. However, the actual process of frost weathering as well as the contribution of further weathering processes (e.g. hydration, thermal fatigue) is poorly understood. Rock moisture distribution during freeze-thaw events is key to understanding weathering. For this purpose, different measuring systems were set up in two study areas (Dachstein - permafrost area (2700m a.s.l.) and Gesäuse - non permafrost area (900m a.s.l.), Styria, Austria) within the framework of the research project ROCKING ALPS (FWF-P24244). We installed small-scale 2D-geoelectric survey lines in north and in south facing rockwalls, supplemented by high resolution temperature and moisture sensors. Moisture is determined by means of resistivity measurements which are difficult to calibrate, but provide good time series. Additional novel moisture sensors were developed which use the heat capacity of the surrounding rock as a proxy of water content. These sensors give point readings from a defined depth and are independent from soluble salt contents. Pore water pressure occurring during freeze-thaw events is recorded by means of pressure transducers (piezometers). First results from the Dachstein show that short term latent heat effects during the phase change have crucial influence on the moisture content. These results are cross-checked by simulation calculations. Based on meteorologic and lithologic input values, the simulation routine calculates, in an iterative procedure, the hourly energy and water transport at different depths, the latter in the liquid and in the vapor phase. The calculated profile lines and chronological sequences of rock moisture allow - in combination with temperature data - to detect possible periods of active weathering. First simulations from the Gesäuse show that maximum values of pore saturation occur from May to September. The thresholds of the "classical" frost shattering theory (high number of freeze-thaw cycles and 90% pore saturation) are achieved predominantly in spring and autumn and in north-facing rock walls. The time spent within the effective "frost cracking window" (-3 - -8°C) is also higher for north-facing sites.

  4. Improving Forecasts of Freezing Rain at ECMWF

    NASA Astrophysics Data System (ADS)

    Tsonevsky, Ivan; Forbes, Richard; Hewson, Tim

    2015-04-01

    Freezing rain events, though relatively rare, can be extremely debilitating and dangerous for society, with recovery times of order months or even years. Analysis of forecasts of past events by the operational ECMWF Integrated Forecast System (IFS) showed a strong tendency to incorrectly represent freezing rain as snow. Investigations highlighted that this was primarily because the re-freezing process in IFS, following hydrometeors as they descend, was parametrised with the same time-scale as the melting process. In reality the time-scale for re-freezing should, in general, be much longer. The model physics were changed accordingly, and the results in terms of forecast quality were positive and very striking. Coupled with these physics changes new IFS output was developed for users which shows precipitation type at the surface (rain, snow, wet snow, sleet, freezing rain, ice pellets). The changes to the physics will be described in detail, and their impact will be illustrated by comparing forecast output for past events in new and old model versions, in terms of precipitation type and intensity. Illustrations will include short-range deterministic forecasts from 'HRES' (the high resolution ECMWF model), and longer range probabilistic forecasts of freezing rain occurrence from the ensemble. There will also be reference to issues requiring further work/investigation, such as high level convection in potential freezing rain cases, freezing drizzle generated in supercooled shallow clouds, and IFS retention of the 'warm nose' in which melting occurs.

  5. Freezing: an underutilized food safety technology?

    PubMed

    Archer, Douglas L

    2004-01-15

    Freezing is an ancient technology for preserving foods. Freezing halts the activities of spoilage microorganisms in and on foods and can preserve some microorganisms for long periods of time. Frozen foods have an excellent overall safety record. The few outbreaks of food-borne illness associated with frozen foods indicate that some, but not all human pathogens are killed by commercial freezing processes. Freezing kills microorganisms by physical and chemical effects and possibly through induced genetic changes. Research is needed to better understand the physical and chemical interactions of various food matrices with the microbial cell during freezing and holding at frozen temperatures. The literature suggests that many pathogenic microorganisms may be sublethally injured by freezing, so research should be done to determine how to prevent injured cells from resuscitating and becoming infectious. Studies on the genetics of microbial stress suggest that the induction of resistance to specific stresses may be counteracted by, for example, simple chemicals. Research is needed to better understand how resistance to the lethal effect of freezing is induced in human pathogens and means by which it can be counteracted in specific foods. Through research, it seems possible that freezing may in the future be used to reliably reduce populations of food-borne pathogens as well as to preserve foods. PMID:14698095

  6. Self healing of high strength concrete after deterioration by freeze/thaw

    SciTech Connect

    Jacobsen, S. [Norwegian Building Research Inst., Oslo (Norway)] [Norwegian Building Research Inst., Oslo (Norway); Sellevold, E.J. [Norwegian Inst. of Technology, Trondheim (Norway)] [Norwegian Inst. of Technology, Trondheim (Norway)

    1996-01-01

    Some experiments have been performed to investigate the self healing of concretes deteriorated by internal cracking in the ASTM C666 procedure A rapid freeze/thaw test. Six different well cured concretes were deteriorated to various degrees. Then the specimens (concrete beams) were stored in water for 2--3 months. Resonance frequency, weight, volume and compressive strength were measured during deterioration and self healing. Concretes that lost as much as 50% of their initial relative dynamic modulus during freeze/thaw could recover almost completely during subsequent storage in water, somewhat varying with concrete composition and degree of deterioration. Compressive strength showed reductions of 22--29% on deterioration, but only 4--5% recovery on self healing. Freeze/thaw tests on deteriorated and self-healed specimens in partly sealed condition showed clearly that the deterioration was governed by the ability to take up water; the more water that leaked through the plastic foil during freeze/thaw, the larger the deterioration. Self healing may be an important factor giving concrete better frost durability in field than when submitting specimens to freeze/thaw cycles in water.

  7. On the Importance of Zero-Point Effects in Molecular Level Classical Simulations of Water

    SciTech Connect

    Burnham, Christian J.; Xantheas, Sotiris S.

    2004-03-15

    We discuss the fundamental difficulties involved in comparing energetic results obtained via classical simulations of bulk water with the observed values. Emphasis is placed on the difference between quantum and classical dynamics and correction techniques, which can be used to emulate quantum effects in a classical system, are investigated. We present molecular dynamics simulation results for liquid water using the ''Thole-type'' all atom polarizable water model, which has previously been shown to give reasonable results for both ice Ih and small water clusters. We employ expressions for the density of states power spectrum in the liquid in either atomic or rigid-body coordinates that are appropriate for rigid molecule simulations. It is demonstrated that the atomic power spectra can be written as a linear combination of the center of mass and rotational power spectra via the use of the ''coupling matrix'' of linear coefficients. This approach allows us to introduce the concept of ''fractional degrees of freedom'' for nuclei in rigid molecule simulation. Within this framework, it is illustrated that, in a rigid water molecule, the Oxygen and Hydrogen atoms have 2.82 and 1.59 degrees of freedom, respectively (for the TIP4P geometry). Within our suggested approach, we finally demonstrate that Debye-Waller factors can be obtained from the coupling matrix and show that quantum corrections to the structure can be accounted for by raising the temperature of the system in a classical simulation by around 500, a result consistent with previous suggestions.

  8. Moisture sorption characteristics of freeze-dried human platelets.

    PubMed

    Xu, Meng-jie; Chen, Guang-ming; Fan, Ju-li; Liu, Jin-hui; Xu, Xian-guo; Zhang, Shao-zhi

    2011-03-01

    Freeze-drying is a promising method for a long-term storage of human platelets. The moisture sorption characteristics of freeze-dried human platelets (FDHPs) were studied in this paper. The moisture sorption isotherms of FDHPs and freeze-dried lyophilization buffer (FDLB) were measured at 4, 25, and 37 °C. The experimental data were fitted to Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) equations. There were no significant statistical differences (P>0.05) between the sorption characteristics of FDHPs and FDLB at 4 and 25 °C, while FDHPs absorbed more water at 37 °C. The net isosteric heat of sorption was derived. The heat for FDHPs showed an abnormal negative value at low moisture contents when 25 and 37 °C data were used. Dynamic sorption experiments were carried out at 25 °C with environmental water activity controlled at 0.75, 0.85, and 0.90. The moisture diffusion coefficient was fitted to be 8.24×10(-12) m(2)/s when experimental data at initial time were used. These results would be helpful in choosing prehydration and storage condition for FDHPs. PMID:21370506

  9. Moisture sorption characteristics of freeze-dried human platelets*

    PubMed Central

    Xu, Meng-jie; Chen, Guang-ming; Fan, Ju-li; Liu, Jin-hui; Xu, Xian-guo; Zhang, Shao-zhi

    2011-01-01

    Freeze-drying is a promising method for a long-term storage of human platelets. The moisture sorption characteristics of freeze-dried human platelets (FDHPs) were studied in this paper. The moisture sorption isotherms of FDHPs and freeze-dried lyophilization buffer (FDLB) were measured at 4, 25, and 37 °C. The experimental data were fitted to Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) equations. There were no significant statistical differences (P>0.05) between the sorption characteristics of FDHPs and FDLB at 4 and 25 °C, while FDHPs absorbed more water at 37 °C. The net isosteric heat of sorption was derived. The heat for FDHPs showed an abnormal negative value at low moisture contents when 25 and 37 °C data were used. Dynamic sorption experiments were carried out at 25 °C with environmental water activity controlled at 0.75, 0.85, and 0.90. The moisture diffusion coefficient was fitted to be 8.24×10?12 m2/s when experimental data at initial time were used. These results would be helpful in choosing prehydration and storage condition for FDHPs. PMID:21370506

  10. Microphysical Modelling of the 1999-2000 Arctic Winter. 3; Impact of Homogeneous Freezing on PSCs

    NASA Technical Reports Server (NTRS)

    Drdla, K.

    2003-01-01

    Simulations of the 1999-2000 winter have tested the effect on polar stratospheric clouds (PSCs) of the homogeneous freezing of liquid ternary solutions into nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD). Proposed laboratory-derived volume-based and surface-based homogeneous freezing rates have both been examined, including different assumptions about the extrapolation of laboratory measurements to atmospheric conditions. Widespread PSC formation and denitrification are possible in several of the scenarios examined. However, the simulations are all unable to explain the solid-phase PSCs observed early in the 1999-2000 winter, and are unable to reproduce the measured extent of vortex denitrification. These problems can both be attributed to the relatively cold temperatures, more than 5 K below the NAT condensation point, necessary for effective homogeneous freezing. Therefore synoptic-scale homogeneous freezing appears unlikely to be the primary mechanism responsible for solid-phase PSC formation.

  11. Freeze-drying for morphological control of high performance semi-interpenetrating polymer networks. III

    NASA Technical Reports Server (NTRS)

    Hsiung, H. J.; Hansen, M. G.; Pater, R. H.

    1991-01-01

    The feasibility of using a freeze-drying (solvent removal by sublimation) approach for controlling the morphology of a high-performance semi-IPN is assessed. A high-performance thermoplastic polyimide and commercially available 4,4'-bismaleimide diphenylenemethane were dissolved in a solvent, 1,3,5-trioxane. The solvent was removed from the constituents by freeze-drying. For purposes of comparison, the constituents were dissolved in a high-boiling-point solvent, N,N-dimethylformamide. The solvent was removed from the solution by evaporation. The physical and mechanical properties and phase morphology of the neat resins and composites prepared by freeze-drying and traditional solution methods are presented and compared. It is concluded that the TG is higher and that the magnitude of minor constituent separation is less in the freeze-dry processed materials than for the processed solution.

  12. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Quick freeze treatment requirements. 305.7 Section 305.7...DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze treatment requirements. Quick freeze...

  13. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Quick freeze treatment requirements. 305.7 Section 305.7...DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze treatment requirements. Quick freeze...

  14. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Quick freeze treatment requirements. 305.7 Section 305.7...DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze treatment requirements. Quick freeze...

  15. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Quick freeze treatment requirements. 305.7 Section 305.7...DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze treatment requirements. Quick freeze...

  16. Water balance of Pin-Point and Flush-Flood irrigated rice 

    E-print Network

    Roel Dellazoppa, Alvaro

    1996-01-01

    Appearance of red rice (Oryza Sativa) as the main weed problem in rice production has forced producers and researchers to develop new irrigation techniques to control the weed. The Pin-Point irrigation method is one of these techniques, but little...

  17. 33 CFR 150.445 - When is oil in a single point mooring-oil transfer system (SPM-OTS) displaced with water?

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    33 ? Navigation and Navigable Waters ? 2 ? 2014-07-01 ? 2014-07-01 ? false ? When is oil in a single point mooring-oil transfer system (SPM-OTS) displaced with water? ? 150.445 ? Section 150.445 ? Navigation and Navigable Waters ? COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ?...

  18. Elastic behavior of saturated porous materials under undrained freezing

    NASA Astrophysics Data System (ADS)

    Zeng, Qiang; Fen-Chong, Teddy; Li, Ke-Fei

    2013-12-01

    The elastic behavior of saturated porous materials under undrained freezing is investigated by using a poromechanical approach. Thermodynamic equilibria are used to describe the crystallization process of the partially frozen solution in bulk state and confined state in pores. By phase transition at freezing, fusion energy, thermal contraction of solid, solution and ice crystals, volume changes of crystallization build up remarkable pore pressure that induces expansion or shrinkage of solid matrix. Owing to the lower chemical potential when pore water mixes with salts, fewer ice forms in pores. Penetration of ice into the porous materials increases the capillary pressure, but limits effect on the pore liquid pressure and the strain of solid matrix. On the contrary, the pore pressure induced by solution density rises as salt concentration increases and causes significant shrinkage of solid matrix.

  19. Investigation of an implantable dosimeter for single-point water equivalent path length verification in proton therapy

    SciTech Connect

    Lu, Hsiao-Ming; Mann, Greg; Cascio, Ethan [Francis H. Burr Proton Therapy Center, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Sicel Technologies, Inc., Morrisville, North Carolina 27560 (United States); Francis H. Burr Proton Therapy Center, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States)

    2010-11-15

    Purpose: In vivo range verification in proton therapy is highly desirable. A recent study suggested that it was feasible to use point dose measurement for in vivo beam range verification in proton therapy, provided that the spread-out Bragg peak dose distribution is delivered in a different and rather unconventional manner. In this work, the authors investigate the possibility of using a commercial implantable dosimeter with wireless reading for this particular application. Methods: The traditional proton treatment technique delivers all the Bragg peaks required for a SOBP field in a single sequence, producing a constant dose plateau across the target volume. As a result, a point dose measurement anywhere in the target volume will produce the same value, thus providing no information regarding the water equivalent path length to the point of measurement. However, the same constant dose distribution can be achieved by splitting the field into a complementary pair of subfields, producing two oppositely ''sloped'' depth-dose distributions, respectively. The ratio between the two distributions can be a sensitive function of depth and measuring this ratio at a point inside the target volume can provide the water equivalent path length to the dosimeter location. Two types of field splits were used in the experiment, one achieved by the technique of beam current modulation and the other by manipulating the location and width of the beam pulse relative to the range modulator track. Eight MOSFET-based implantable dosimeters at four different depths in a water tank were used to measure the dose ratios for these field pairs. A method was developed to correct the effect of the well-known LET dependence of the MOSFET detectors on the depth-dose distributions using the columnar recombination model. The LET-corrected dose ratios were used to derive the water equivalent path lengths to the dosimeter locations to be compared to physical measurements. Results: The implantable dosimeters measured the dose ratios with a reasonable relative uncertainty of 1%-3% at all depths, except when the ratio itself becomes very small. In total, 55% of the individual measurements reproduced the water equivalent path lengths to the dosimeters within 1 mm. For three dosimeters, the difference was consistently less than 1 mm. Half of the standard deviations over the repeated measurements were equal or less than 1 mm. Conclusions: With a single fitting parameter, the LET-correction method worked remarkably well for the MOSFET detectors. The overall results were very encouraging for a potential method of in vivo beam range verification with millimeter accuracy. This is sufficient accuracy to expand range of clinical applications in which the authors could use the distal fall off of the proton depth dose for tight margins.

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

    PubMed

    Roma, E; Bond, T; Jeffrey, P

    2014-09-01

    Many scientific studies have suggested that point-of-use water treatment can improve water quality and reduce the risk of infectious diseases. Despite the ease of use and relatively low cost of such methods, experience shows the potential benefits derived from provision of such systems depend on recipients' acceptance of the technology and its sustained use. To date, few contributions have addressed the problem of user experience in the post-implementation phase. This can diagnose challenges, which undermine system longevity and its sustained use. A qualitative evaluation of two household water treatment systems, solar disinfection (SODIS) and chlorine tablets (Aquatabs), in three villages was conducted by using a diagnostic tool focusing on technology performance and experience. Cross-sectional surveys and in-depth interviews were used to investigate perceptions of involved stakeholders (users, implementers and local government). Results prove that economic and functional factors were significant in using SODIS, whilst perceptions of economic, taste and odour components were important in Aquatabs use. Conclusions relate to closing the gap between factors that technology implementers and users perceive as key to the sustained deployment of point-of-use disinfection technologies. PMID:25252361

  1. Freeze-Thaw Stress: Effects of Temperature on Hydraulic Conductivity and Ultrasonic Activity in Ten Woody Angiosperms1

    PubMed Central

    Charrier, Guillaume; Charra-Vaskou, Katline; Kasuga, Jun; Cochard, Hervé; Mayr, Stefan; Améglio, Thierry

    2014-01-01

    Freeze-thaw events can affect plant hydraulics by inducing embolism. This study analyzed the effect of temperature during the freezing process on hydraulic conductivity and ultrasonic emissions (UE). Stems of 10 angiosperms were dehydrated to a water potential at 12% percentage loss of hydraulic conductivity (PLC) and exposed to freeze-thaw cycles. The minimal temperature of the frost cycle correlated positively with induced PLC, whereby species with wider conduits (hydraulic diameter) showed higher freeze-thaw-induced PLC. Ultrasonic activity started with the onset of freezing and increased with decreasing subzero temperatures, whereas no UE were recorded during thawing. The temperature at which 50% of UE were reached varied between ?9.1°C and ?31.0°C across species. These findings indicate that temperatures during freezing are of relevance for bubble formation and air seeding. We suggest that species-specific cavitation thresholds are reached during freezing due to the temperature-dependent decrease of water potential in the ice, while bubble expansion and the resulting PLC occur during thawing. UE analysis can be used to monitor the cavitation process and estimate freeze-thaw-induced PLC. PMID:24344170

  2. Are the debates on water privatization missing the point? Experiences from Africa, Asia and Latin America

    Microsoft Academic Search

    Jessica Budds; Gordon McGranahan

    2003-01-01

    This paper has two principal aims: first, to unravel some of the arguments mobilized in the controversial privatization debate, and second, to review the scale and nature of private sector provision of water and sanitation in Africa, Asia and Latin America. Despite being vigorously promoted in the policy arena and having been implemented in several countries in the South in

  3. Anomalous Behavior of Proton Zero Point Motion in Water Confined in Carbon Nanotubes

    Microsoft Academic Search

    G. Reiter; C. Burnham; D. Homouz; P. M. Platzman; J. Mayers; T. Abdul-Redah; A. P. Moravsky; J. C. Li; C.-K. Loong; A. I. Kolesnikov

    2006-01-01

    The momentum distribution of the protons in ice Ih, ice VI, high density amorphous ice, and water in carbon nanotubes has been measured using deep inelastic neutron scattering. We find that at 5 K the kinetic energy of the protons is 35 meV less than that in ice Ih at the same temperature, and the high momentum tail of the

  4. UV-TUBE DESIGN CONCEPT FOR SUSTAINABLE, POINT-OF-USE WATER DISINFECTION

    EPA Science Inventory

    The 2002 World Health Organization (WHO) report on worldwide mortality indicates that waterborne illnesses associated with unsafe drinking water and poor sanitation are still a major cause of death in the developing world. Although a variety of methods exist for treating dr...

  5. Yoghurt with candied chestnut: freeze drying, physical, and rheological behaviour.

    PubMed

    Sakin-Yilmazer, Melike; Dirim, S Nur; Di Pinto, Davide; Kaymak-Ertekin, Figen

    2014-12-01

    As a novel product, yoghurt powder was produced by freeze drying and with added candied chestnut puree at ratios of 5, 10, and 20 % by weight. During the freeze drying process, mass loss, water activity, and the moisture content of the samples were determined and the colour (Hunter L, a, b) of the yoghurt powder products was measured. Results showed that increasing the percentage of candied chestnut puree resulted in an increase in water activity, moisture content, and colour change values of the end product. The drying behaviour, drying rate versus free moisture content, was also investigated. It was observed that yoghurt with or without added candied chestnut puree could be satisfactorily freeze-dried. Moreover, the performance of the dried product was observed in a ready-to-use, reconstituted form. For this purpose, the obtained powders were reconstituted to their original moisture contents. Shear stress and apparent viscosity against shear rate in a range of 1-1,000 (1/sec) was then measured by a Haake-Mars rotary viscometer. According to the results, the apparent viscosities of reconstituted products, as plain yoghurt and the one with an added 5 % chestnut puree were lower than that of fresh yoghurt. However, reconstituted yoghurts containing 10 % and 20 % chestnut puree had apparent viscosities higher than fresh yoghurt. Power Law explained well the rheological behaviour of reconstituted yoghurt samples for the applied shear rate range. Based on rheological data and sensory analysis, it was concluded that the freeze dried yoghurt containing 10 % (w/w) candied chestnut puree was an acceptable novel product. PMID:25477665

  6. Conversion of the chill susceptible fruit fly larva (Drosophila melanogaster) to a freeze tolerant organism.

    PubMed

    Koštál, Vladimír; Šimek, Petr; Zahradní?ková, Helena; Cimlová, Jana; Št?tina, Tomáš

    2012-02-28

    Among vertebrates, only a few species of amphibians and reptiles tolerate the formation of ice crystals in their body fluids. Freeze tolerance is much more widespread in invertebrates, especially in overwintering insects. Evolutionary adaptations for freeze tolerance are considered to be highly complex. Here we show that surprisingly simple laboratory manipulations can change the chill susceptible insect to the freeze tolerant one. Larvae of Drosophila melanogaster, a fruit fly of tropical origin with a weak innate capacity to tolerate mild chilling, can survive when approximately 50% of their body water freezes. To achieve this goal, synergy of two fundamental prerequisites is required: (i) shutdown of larval development by exposing larvae to low temperatures (dormancy) and (ii) incorporating the free amino acid proline in tissues by feeding larvae a proline-augmented diet (cryopreservation). PMID:22331891

  7. Remobilization of residual non-aqueous phase liquid in porous media by freeze-thaw cycles.

    PubMed

    Singh, Kamaljit; Niven, Robert K; Senden, Timothy J; Turner, Michael L; Sheppard, Adrian P; Middleton, Jill P; Knackstedt, Mark A

    2011-04-15

    The pore-scale behavior of a nonaqueous phase liquid (NAPL) trapped as residual contamination in a porous medium, subject to freeze-thaw cycles, was investigated by X-ray microcomputed tomography. It is shown that freeze-thaw cycles cause significant NAPL remobilization in the direction of the freezing front, due to the rupture and transport of a significant proportion of (supposedly entrapped) larger multipore NAPL ganglia. Significant NAPL remains in place, however, due to substantial ganglion fragmentation into single- and subpore ganglia. The contraction of branched ganglia into more rounded forms, especially near the top surface, is also observed. Three freezing-induced mechanisms are proposed to explain the results. The findings have important implications for NAPL contamination in cold regions, and for the behavior of water-hydrocarbon systems on the Earth and other planets. PMID:21438639

  8. Evaluation of green tea extract as a glazing material for shrimp frozen by cryogenic freezing.

    PubMed

    Sundararajan, Srijanani; Prudente, Alfredo; Bankston, J David; King, Joan M; Wilson, Paul; Sathivel, Subramaniam

    2011-09-01

    Solutions of green tea (Camellia sinensis) extract (GTE) in distilled water were evaluated as a glazing material for shrimp frozen by cryogenic freezing. Total of 2%, 3%, and/or 5% GTE solutions (2GTE, 3GTE, 5GTE) were used for glazing. Distilled water glazed (GDW) and nonglazed shrimp (NG) served as controls. The GTE was characterized by measuring color, pH, (o) Brix, total phenols, and % antiradical activity. Individual catechins were identified by HPLC. The freezing time, freezing rate, and energy removal rate for freezing shrimp by cryogenic freezing process were estimated. The frozen shrimp samples were stored in a freezer at -21 °C for 180 d. Samples were analyzed for pH, moisture content, glazing yield, thaw yield, color, cutting force, and thiobarbituric acid reactive substances (TBARS) after 1, 30, 90, and 180 d. The HPLC analysis of GTE revealed the presence of catechins and their isomers and the total polyphenol content was 148.10 ± 2.49 g/L. The freezing time (min) and energy removal rate (J/s) were 48.67 ± 2.3 and 836.67 ± 78.95, respectively. Glazed samples had higher moisture content compared to NG shrimp after 180 d storage. GTE was effective in controlling the lipid oxidation in shrimp. Glazing with GTE affected a* and b* color values, but had no significant effect on the L* values of shrimp. PMID:22417550

  9. The development of point-of-use water filters as sampling devices in bioforensics: extent of microbial sorption and elution.

    PubMed

    Sedillo, Jennifer L; Quintana, Ayshea; Souza, Kathryn; Oshima, Kevin H; Smith, Geoffrey B

    2008-06-01

    The foundational idea for this project is that household faucet-mounted water filters may be used as bioforensic sampling devices to detect the extent of a potential bioagent release in domestic water supplies. An optimized eluent solution was determined experimentally by quantifying recoveries of microorganisms from point-of-use (POU) drinking water filters. The optimized extraction protocol was then used in mock bioagent release experiments to determine the feasibility of POU filters as bioforensic sampling devices. Bacillus atrophaeus spores, Escherichia coli and PP7 virus were exposed to filters and the number of attached organisms was determined by enumerating the unattached organisms on selective agar media. Subsequently, the filters were eluted and the percent of extracted organisms was determined based on the number of attached organisms. Two popular brands of carbon block filters retained 92%-99% of representative virus, spore and vegetative bacteria. In back-flush elutions of single filters, the most efficient eluent was identified as a combination of 1% peptone and 1% Tween-80, and extraction recovered 25.4% (+/-17.5%) of attached E. coli, 20.4% (+/-3.6%) of B. atrophaeus spores, and 9.4% (+/-5.2%) of PP7 virions (+/- standard deviations). In bioagent release studies in which filters were challenged with 100 agents mL(-1), greater than 99% of the spores were retained by the filters, and the percent of attached spores that were recovered ranged from 10.4% at day 0 to 4.3% five days after the release event (averaged from five separate experiments). In contrast, E. coli, Salmonella typhimurium and PP7 virus were rapidly inactivated in the chlorinated tap water, indicating their improbable survival in chlorinated water supplies. It is therefore concluded that household water filters can be used as microbial sampling devices for bioforensic applications in the event of a bioagent release in domestic drinking water supplies. PMID:18528538

  10. On the osmotically unresponsive water compartment in cells.

    PubMed

    Fullerton, Gary D; Kanal, Kalpana M; Cameron, Ivan L

    2006-01-01

    Differences in colligative properties (freezing point, boiling point, vapor pressure and osmotic behavior) between water in living cells and pure bulk water were investigated by re-evaluating reports of the osmotic behavior of mammalian cells. In five different animal cells, osmotically unresponsive water (OUW) values ranged from 1.1 to 2.2 g per g dry mass. Detailed analysis of human red blood cell (RBC) data indicates a major role for hemoglobin OUW-values, aggregation and packing in cell volume regulation that can be explained for the first time in relevant molecular terms. PMID:16360324

  11. Water under inner pressure: A dielectric spectroscopy study

    NASA Astrophysics Data System (ADS)

    Angulo-Sherman, Abril; Mercado-Uribe, Hilda

    2014-02-01

    Water is the most studied substance on Earth. However, it is not completely understood why its structural and dynamical properties give rise to some anomalous behaviors. Some of them emerge when experiments at low temperatures and/or high pressures are performed. Here we report dielectric measurements on cold water under macroscopically constrained conditions, i.e., water in a large container at constant volume that cannot freeze below the melting point. The inner pressure in these conditions shifts the ? relaxation peak to similar frequencies as seen in ice Ih. At 267 K we observe a peculiar response possibly due to the Grotthuss mechanism. At 251 K (the triple point) ice III forms.

  12. Cloud Point Preconcentration and Flame Atomic Absorption Spectrometric Determination of Cobalt and Nickel in Water Samples

    Microsoft Academic Search

    Jamshid L. Manzoori; Ahad Bavili-Tabrizi

    2003-01-01

    .  ?Cloud point methodology was successfully used to preconcentrate trace amounts of Co and Ni as a prior step to their determination\\u000a by flame atomic absorption spectrometry. 1-Nitroso-2-naphthol and polyethylene glycol-p-nonylphenylether (PONPE 7.5) are used\\u000a as hydrophobic ligand and nonionic surfactant, respectively. Optimization was performed of the variables effecting complexation\\u000a and phase separation. Additionally, the influence of viscosity on the analytical

  13. Calculation of electron Dose Point Kernel in water with GEANT4 for medical application

    Microsoft Academic Search

    M. Moralles; F. F. Sene; J. R. Martinelli; E. Okuno

    2009-01-01

    The rapid insertion of new technologies in medical physics in the last years, especially in nuclear medicine, has been followed by a great development of faster Monte Carlo algorithms. GEANT4 is a Monte Carlo toolkit that contains the tools to simulate the problems of particle transport through matter. In this work, GEANT4 was used to calculate the dose-point-kernel (DPK) for

  14. 33 CFR 154.2112 - Vapors with potential to polymerize or freeze-Special requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Navigation and Navigable Waters 2 2014-07-01 2014-07-01... Navigation and Navigable Waters COAST GUARD, DEPARTMENT...prevents the freezing of vapors or condensate at ambient temperature or that detects and removes the liquid condensate and solids to prevent...

  15. Dilatometrical behaviour of porous calcareous rock samples subjected to freeze-thaw cycles

    Microsoft Academic Search

    A. Prick

    1995-01-01

    Dilatometry can be used in geomorphology as an evaluation method for the behaviour of rocks during weathering by frost shattering and also for the role of unfrozen water migration during this process. It has already been demonstrated in other publications that calcareous rock cylinders undergoing humidification\\/drying cycles (no freezing) vary in length. These length changes are most significant when water

  16. Point-spread function associated with underwater imaging through a wavy air-water interface: theory and laboratory tank experiment.

    PubMed

    Brown, W C; Majumdar, A K

    1992-12-20

    The point-spread function needed for imaging underwater objects is theoretically derived and compared with experimental results. The theoretical development is based on the emergent-ray model, in which the Gram-Charlier series for the non-Gaussian probability-density function for emergent angles through a wavy water surface was assumed. To arrive at the point-spread model, we used a finite-element methodology with emergent-ray angular probability distributions as fundamental building functions. The model is in good agreement with the experiment for downwind conditions. A slight deviation between theory and experiment was observed for the crosswind case; this deviation may be caused by the possible interaction of standing waves with the original air-ruffled capillary waves that were not taken into account in the model. PMID:20802646

  17. The 2008 South China Freeze and its Impact on the Forests

    NASA Astrophysics Data System (ADS)

    Zhou, B.; Ai, C.; Wang, Y.; Li, Z.; Cao, Y.; Wang, X.

    2008-12-01

    An unprecedented calamity caused by snow and freezing rain occurred in South China in 2008. This freeze was closely related to the La Nina phenomenon according to a report from the World Meteorological Organization. The freeze stroke 19 provinces in China, and damaged forests of 19.33 million ha with a standing volume loss of 371 million m3. It is estimated that the direct economic loss in the form of destroyed forests is over $8 billion. The indirect loss in the form of impaired ecological functions, such as water and soil conservation, water resources conservancy, biodiversity and forest carbon pool etc is enormous. The calamity of snow and freezing rain affected the structure and function of forest ecosystems. The snow load and freezing rain caused mechanical damage to the trees, with the species of Pinus massoniana, Cunninghamia lanceolata, Pinus elliottii and Phyllostachys pubescens etc. being the most seriously affected. The cold weather could also cause the physiological hurt to the trees. The change of the biotic components leads to the change of abiotic components in the ecosystems. The sunlight under the canopy was intensified due to the opening up of the canopy. The air temperature in the forest, the nutrient and microorganism in soil, the litterfall dynamic were also affected. The alteration of the forest ecosystem structure brought in the alteration of its functions. The damage of the ecosystem structure weakened the capacity of the water and soil conservation, water resources conservancy and reduced the biodiversity in forest ecosystems. Forest gaps allow more sunlight into the freeze-damaged ecosystem, inducing the invasion of more masculine species. The direction and progress of the community succession was therefore altered. At the same time, the freeze made a great impact on the stability and health of the forest ecosystem, increasing the potential risk of outbreak of forest fire and plant diseases/insect pests. Some suggestions on the rebuilding and recovery of damaged forest were given in this paper.

  18. At Boiling Point: Like Water for Chocolate and the Boundaries of Mexican Identity

    Microsoft Academic Search

    N. Finnegan

    1999-01-01

    This article explores the mechanisms of Mexican identity as they are constructed in Alfonso Arau’s film Como agua para chocolate (1991) (Like Water for Chocolate). In re-designing the characters of Laura Esquivel’s novel, Arau produces a range of filmic stereotypes drawn from both the Hollywood and the Mexican traditions of film-making. Through the careful manipulation of filmic devices such as

  19. Determination of Prometryne in water and soil by HPLC–UV using cloud-point extraction

    Microsoft Academic Search

    Jihai Zhou; Jiandong Chen; Yanhong Cheng; Daming Li; Feng Hu; Huixin Li

    2009-01-01

    A CPE-HPLC (UV) method has been developed for the determination of Prometryne. In this method, non-ionic surfactant Triton X-114 was first used to extract and pre-concentrate Prometryne from water and soil samples. The separation and determination of Prometryne were then carried out in an HPLC–UV system with isocratic elution using a detector set at 254nm wavelength. The parameters and variables

  20. Assessment of a low-cost, point-of-use, ultraviolet water disinfection technology

    Microsoft Academic Search

    Sarah A. Brownell; Alicia R. Chakrabarti; Forest M. Kaser; Fermin Reygadas; Micah J. Lang; Lloyd G. Connelly; Rachel L. Peletz; Daniel M. Kammen; Kara L. Nelson

    2008-01-01

    fluence of 900 ^ 80J\\/m2 (95% CI) in water with an absorption coefficient of 0.01cm21. The residence time distribution in the UV Tube was characterized as plug flow with dispersion (Peclet Number ¼ 19.7) and a mean hydraulic residence time of 36s. Undesirable compounds were leached or produced from UV Tubes constructed with unlined ABS, PVC, or a galvanized steel