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1

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...

2

When hot water freezes before cold  

Microsoft Academic Search

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

J. I. Katz

2006-01-01

3

Water adsorption-desorption isotherms of two-dimensional hexagonal mesoporous silica around freezing point.  

PubMed

Zr-doped mesoporous silica with a diameter of approximately 3.8 nm was synthesized via an evaporation-induced self-assembly process, and the adsorption-desorption isotherms of water vapor were measured in the temperature range of 263-298 K. The measured adsorption-desorption isotherms below 273 K indicated that water confined in the mesopores did not freeze at any relative pressure. All isotherms had a steep curve, resulting from capillary condensation/evaporation, and a pronounced hysteresis. The hysteresis loop, which is associated with a delayed adsorption process, increased with a decrease in temperature. Furthermore, the curvature radius where capillary evaporation/condensation occurs was evaluated by the combined Kelvin and Gibbs-Tolman-Koening-Buff (GTKB) equations for the modification of the interfacial tension due to the interfacial curvature. The thickness of the water adsorption layer for capillary condensation was slightly larger, whereas that for capillary evaporation was slightly smaller than 0.7 nm. PMID:22041197

Endo, Akira; Yamaura, Toshio; Yamashita, Kyohei; Matsuoka, Fumio; Hihara, Eiji; Daiguji, Hirofumi

2012-02-01

4

Freezing of supercooled water nanodroplets  

NASA Astrophysics Data System (ADS)

All three states of water play important roles in nature, from thermostating the atmosphere to providing reactive surfaces environments. The rates at which transitions between the phases occur, the degree to which pure liquid water can be supercooled, and the solid phases that form are all fundamentally interesting questions with strong atmospheric relevance. We have followed and characterized the nucleation, growth, and subsequent freezing of pure water droplets formed in a supersonic nozzle apparatus using both Small Angle X-ray Scattering (SAXS) and Fourier Transform Infrared Spectroscopy (FTIR). Because the droplets have radii r between 3 nm and 6 nm, and the cooling rates are on the order of 5E5 K/s, liquid water only begins to freeze below approximately 215 K. These temperatures are well below the homogeneous freezing limit for bulk water. The experiments show the expected decrease in freezing temperature with decreasing droplet size, or alternatively, with increasing droplet internal pressure.

Wyslouzil, Barbara

2013-03-01

5

Device and method for determining freezing points  

NASA Technical Reports Server (NTRS)

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).

Mathiprakasam, Balakrishnan (Inventor)

1986-01-01

6

Freezing kinetics in overcompressed water  

Microsoft Academic Search

The transformation of water into ice is among the most common first order phase transitions occurring in nature, but it is far from being an ordinary one. Water has unusual physical properties both as a liquid and as a solid due largely to hydrogen bonding effects, which also play a major role in determining the characteristics of its freezing kinetics.

Marina Bastea; Sorin Bastea; John Reaugh; David Reisman

2007-01-01

7

Effects of Dissolved Oxygen and Freezing Techniques on the Silver Freezing Point  

Microsoft Academic Search

The freezing point of silver is being considered as a joining point between platinum resistance thermometry and optical pyrometry. Therefore the freezing points of high purity samples of silver have been investigated. An important impurity effect arises from the depression of the freezing point of pure Ag caused by residual dissolved oxygen contents in some samples. Melting range parameters were

G. Bongiovanni; L. Crovini; P. Marcarino

1975-01-01

8

Freezing kinetics in overcompressed water  

NASA Astrophysics Data System (ADS)

The transformation of water into ice is among the most common first order phase transitions occurring in nature, but it is far from being an ordinary one. Water has unusual physical properties both as a liquid and as a solid due largely to hydrogen bonding effects, which also play a major role in determining the characteristics of its freezing kinetics. We report high pressure dynamic compression experiments of liquid water along a quasi-adiabatic path leading to the formation of ice VII. We observe dynamic features resembling Van der Waals loops and find that liquid water is compacted to a metastable state close to the ice density before the onset of crystallization. By analyzing the characteristic kinetic time scale involved we estimate the nucleation barrier and conclude that liquid water has been compressed to a high pressure state close to its thermodynamic stability limit.

Bastea, Marina; Bastea, S.; Reaugh, J.; Reisman, D.

2007-03-01

9

The Siberian timberman Acanthocinus aedilis: a freeze-tolerant beetle with low supercooling points.  

PubMed

Larvae of the Siberian timberman beetle Acanthocinus aedilis display a number of unique features, which may have important implications for the field of cold hardiness in general. Their supercooling points are scattered over a wide temperature range, and some individuals have supercooling points in the low range of other longhorn beetles. However, they differ from other longhorn beetles in being tolerant to freezing, and in the frozen state they tolerate cooling to below -37 degrees C. In this respect they also differ from the European timberman beetles, which have moderate supercooling capacity and die if they freeze. The combination of freezing tolerance and low supercooling points is unusual and shows that freezing at a high subzero temperature is not an absolute requirement for freezing tolerance. Like other longhorn beetles, but in contrast to other freeze-tolerant insects, the larvae of the Siberian timberman have a low cuticular water permeability and can thus stay supercooled for long periods without a great water loss. This suggests that a major function of the extracellular ice nucleators of some freeze-tolerant insects may be to prevent intolerable water loss in insects with high cuticular water permeability, rather than to create a protective extracellular freezing as has generally been assumed. The freezing tolerance of the Siberian timberman larvae is likely to be an adaptation to the extreme winter cold of Siberia. PMID:19153749

Kristiansen, E; Li, N G; Averensky, A I; Laugsand, A E; Zachariassen, K E

2009-07-01

10

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

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…

Tellinghuisen, Joel

2010-01-01

11

Freezing Phenomena in Adsorbed Water as Studied by NMR  

NASA Astrophysics Data System (ADS)

The freezing of water adsorbed on high-surface-area materials such as silica gel, controlled-pore glass, and activated charcoal is investigated with NMR methods. Part of the pore water freezes at the temperature predicted by the Kelvin equation and the rest of the water does not freeze in the sense that it does not assume the structure of ice on cooling below this freezing point. This bound water exhibits a distribution of correlation times, and information about the width of this distribution is obtained. Values for the activation enthalpy of the bound water are also deduced. An alternative method for the determination of the pore volume of an adsorbent is proposed and it is shown that. for adsorbents with small pores ( r < 100 Å), this method results in a much better estimate for the total pore volume than the more common mercury-intrusion method.

Overloop, K.; Vangerven, L.

12

Inherent freeze protection for solar water heaters  

SciTech Connect

Research and development of a method for protection of a solar collector from freezing is described. The method is shown to be technically and economically feasible. A prototype water heating system using the inherent freeze protection method was successfully operated during the winter of 1980 to 1981.

Jeter, S.M.; Leonaitis, L.L.; Leonaitis, L.L.

1981-05-01

13

Freezing Ice  

NSDL National Science Digital Library

The purpose of this assessment probe is to elicit students' ideas about freezing point. The probe is designed to find out whether students recognize that water freezes at the same time independent of the volume of water.

Eberle, Francis; Tugel, Joyce; Keeley, Page

2007-01-01

14

Realization of the Copper Freezing Point by Pyrometry.  

National Technical Information Service (NTIS)

The scope of the paper is to describe the apparatus and method of the realization of the copper freezing point using the NIM's photoelectric comparator. The standard deviation of the point was estimated to be 0.02 deg C. The overall uncertainty in this re...

Q. Zhao D. Li Z. Yuan Z. Chang

1987-01-01

15

High-freezing-point fuels used for aviation turbine engines  

NASA Technical Reports Server (NTRS)

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.

Friedman, R.

1979-01-01

16

The Freezing Point Depression Law in Physical Chemistry.  

ERIC Educational Resources Information Center

Suggests a change in physical chemistry courses to use a slightly more complicated but significantly more useful generalization of the simple freezing point depression law. Lists reasons for the change and presents the treatment of solid-liquid equilibria where solid-solution is allowed. Provides a mathematical treatment. (MVL)

Franzen, Hugo F.

1988-01-01

17

Freezing kinetics in overcompressed water  

Microsoft Academic Search

We report high-pressure dynamic compression experiments of liquid water along a quasiadiabatic path leading to the ice-VII region of the phase diagram. We observe dynamic features resembling van der Waals loops and find that liquid water is compacted to a metastable state close to the ice density before the onset of crystallization. By analyzing the characteristic kinetic time scale involved

Marina Bastea; Sorin Bastea; John E. Reaugh; David B. Reisman

2007-01-01

18

Freezing Kinetics in Overcompressed Water  

SciTech Connect

We report high pressure dynamic compression experiments of liquid water along a quasi-adiabatic path leading to the formation of ice VII. We observe dynamic features resembling Van der Waals loops and find that liquid water is compacted to a metastable state close to the ice density before the onset of crystallization. By analyzing the characteristic kinetic time scale involved we estimate the nucleation barrier and conclude that liquid water has been compressed to a high pressure state close to its thermodynamic stability limit.

Bastea, M; Bastea, S; Reaugh, J; Reisman, D

2006-09-27

19

Freezing kinetics in overcompressed water  

NASA Astrophysics Data System (ADS)

We report high-pressure dynamic compression experiments of liquid water along a quasiadiabatic path leading to the ice-VII region of the phase diagram. We observe dynamic features resembling van der Waals loops and find that liquid water is compacted to a metastable state close to the ice density before the onset of crystallization. By analyzing the characteristic kinetic time scale involved we estimate the nucleation barrier and conclude that liquid water has been compressed to a high-pressure state close to its thermodynamic stability limit.

Bastea, Marina; Bastea, Sorin; Reaugh, John E.; Reisman, David B.

2007-05-01

20

High freezing point fuels used for aviation turbine engines  

NASA Technical Reports Server (NTRS)

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.

Friedman, R.

1979-01-01

21

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

22

A Study of Corona Discharges at Water Drops Over the Freezing Temperature Range  

Microsoft Academic Search

Foul weather corona have been observed to behave differently at temperatures above and below the freezing point1.2. Generally speaking, the discharge activities are much more intensive at temperatures above than below the freezing point. Such behaviour of the discharge is so far associated with the differences in the physical properties of water in its liquid and solid phases. No detailed

J. Luan Phan-Cong; Pol Pirotte; Rene Brunelle; N. G. Trinh

1974-01-01

23

Standard Reference Materials: Standard Reference Material 1747: Tin Freezing-Point Cell and Standard Reference Material 1748: Zinc Freezing-Point Cell.  

National Technical Information Service (NTIS)

The freezing points of Sn (231.928 deg C) and Zn (419.527 deg C) are defining fixed points of the International Temperature Scale of 1990 (ITS-90). Realization of these freezing points is performed using fixed-points cells containing high-purity (> or = 9...

G. F. Strouse A. T. Ince

1997-01-01

24

Experimental results for the rapid determination of the freezing point of fuels  

NASA Technical Reports Server (NTRS)

Two methods for the rapid determination of the freezing point of fuels were investigated: an optical method, which detected the change in light transmission from the disappearance of solid particles in the melted fuel; and a differential thermal analysis (DTA) method, which sensed the latent heat of fusion. A laboratory apparatus was fabricated to test the two methods. Cooling was done by thermoelectric modules using an ice-water bath as a heat sink. The DTA method was later modified to eliminate the reference fuel. The data from the sample were digitized and a point of inflection, which corresponds to the ASTM D-2386 freezing point (final melting point), was identified from the derivative. The apparatus was modifified to cool the fuel to -60 C and controls were added for maintaining constant cooling rate, rewarming rate, and hold time at minimum temperature. A parametric series of tests were run for twelve fuels with freezing points from -10 C to -50 C, varying cooling rate, rewarming rate, and hold time. Based on the results, an optimum test procedure was established. The results showed good agreement with ASTM D-2386 freezing point and differential scanning calorimetry results.

Mathiprakasam, B.

1984-01-01

25

A search for the Mpemba effect: When hot water freezes faster then cold water  

Microsoft Academic Search

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 have different spontaneous freezing temperatures; that is, the temperature at which freezing begins. When both specimens supercool and the spontaneous freezing temperature of the hot water is higher than that of the cold water,

James D. Brownridge

2010-01-01

26

Factors Influencing Freezing of Supercooled Water in Tender Plants1  

Microsoft Academic Search

Seedlings of beans (Phaseolus vulgaris), corn (Zea mays), and tomatoes (Lycopersicon esculentum) were grown in the greenhouse and then exposed to controlled freezing conditions in a growth chamber. Variables were adjusted to determine the influence of plant water potential, freez- ing time, and external dew formation on the seedlings' susceptibility to frost injury. Freezing, detected visually and by release of

J. W. Cary

1970-01-01

27

Chilled water coil freeze protection via internal drying  

SciTech Connect

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.

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

1997-12-01

28

Freezing Characteristics of Molding Sand with Water by Cold Air Flow for Freeze Mold  

NASA Astrophysics Data System (ADS)

This paper reports the freezing characteristics of sand molded with "the freeze mold method". The freeze mold method is the casting process where little water is added to cast sand then they are frozen and become harden as a mold. Instead of using organic hardener, this molding technology possibly reduces resources and environment loading. We aimed at the practical application of the freeze mold method and chose cold airflow as the medium taking heat away from the mold. At first the sand with water was filled into a rectangular container that is the test section. Then cold air flowed into the container. Consequently, the mold was cooled and frozen by the cold airflow. The freezing behavior of the sample by cold airflow was investigated experimentally under the conditions of added water amount, superficial velocity, inflow air temperature and fixed bed height. As a result, the freezing completion time becomes long as the added water amount increases. However, an increase in the added water amount doesn't influence the pressure loss of the test section so much. Moreover, the empirical equation was derived to predict the freezing completion time.

Horibe, Akihiko; Inaba, Hideo; Haruki, Naoto; Miyagawa, Yasunori

29

Standard Reference Materials: Tin Freezing-Point Standard: SRM 741a.  

National Technical Information Service (NTIS)

The freezing point of tin (231.928 degrees C) is a defining fixed point of the International Temperature Scale of 1990 (ITS-90). Realization of this freezing point is performed using a fixed-point cell containing high-purity (> or = 99.9999% pure) tin. A ...

G. F. Strouse N. P. Moiseeva

1999-01-01

30

A calorimeter to detect freezing in supercooled water droplets  

NASA Astrophysics Data System (ADS)

This apparatus suspends a 1 ?l water droplet on an ultraminiature thermistor and uses a Peltier cooling device to supercool the droplet. Electrical connections to the thermistor allow the temperature of the droplet to be constantly monitored, and they also permit direct electrical heating of the droplet after freezing has occurred. Deionized water droplets can be readily supercooled to temperatures of -20 °C before freezing, and repeated determinations of the freezing temperature for the same droplet are straightforward. The temperature characteristics of the phase change are very well defined, and the apparatus therefore permits many other investigations on the provocation of freezing in a supercooled droplet.

Harrison, R. G.; Lodge, B. N.

1998-11-01

31

Melting and freezing of water in cylindrical silica nanopores.  

PubMed

Freezing and melting of H(2)O and D(2)O in the cylindrical pores of well-characterized MCM-41 silica materials (pore diameters from 2.5 to 4.4 nm) was studied by differential scanning calorimetry (DSC) and (1)H NMR cryoporometry. Well-resolved DSC melting and freezing peaks were obtained for pore diameters down to 3.0 nm, but not in 2.5 nm pores. The pore size dependence of the melting point depression DeltaT(m) can be represented by the Gibbs-Thomson equation when the existence of a layer of nonfreezing water at the pore walls is taken into account. The DSC measurements also show that the hysteresis connected with the phase transition, and the melting enthalpy of water in the pores, both vanish near a pore diameter D* approximately equal to 2.8 nm. It is concluded that D* represents a lower limit for first-order melting/freezing in the pores. The NMR spin echo measurements show that a transition from low to high mobility of water molecules takes place in all MCM-41 materials, including the one with 2.5 nm pores, but the transition revealed by NMR occurs at a higher temperature than indicated by the DSC melting peaks. The disagreement between the NMR and DSC transition temperatures becomes more pronounced as the pore size decreases. This is attributed to the fact that with decreasing pore size an increasing fraction of the water molecules is situated in the first and second molecular layers next to the pore wall, and these molecules have slower dynamics than the molecules in the core of the pore. PMID:18825292

Jähnert, S; Vaca Chávez, F; Schaumann, G E; Schreiber, A; Schönhoff, M; Findenegg, G H

2008-10-21

32

A Study of the Realization of the Melting and Freezing Points of Silver  

NASA Astrophysics Data System (ADS)

Freezing and melting behaviour of our silver sample was studied using conventional procedures and also using conditions that were nearly adiabatic in order to obtain an equilibrium melting curve. The results indicate that the freezing point of a silver sample of six-9s purity is reproducible well within one millikelvin, provided that experimental conditions to realize it are reproduced. the melting range from 10% liquid to the liquidus point is about 28 mK, and the freezing point obtained following a supercool can be one to several mK below the liquidus point, depending upon the freezing technique used.

Ancsin, J.

1989-01-01

33

Plant Moisture Stress: A Portable Freezing-Point Meter Compared with the Psychrometer1  

Microsoft Academic Search

A small portable instrument for measuring the freezing- point depression of plant tissue has been developed for field use. The instrument is easy to operate and can be constructed from materials costing less than $100. Moisture stress measurements made with the Freezing- point meter on a variety of plants were compared with vapor pressure psychrometer measurments. Variation be- tween duplicates

J. W. Cary; H. D. Fisher

1969-01-01

34

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

NASA Technical Reports Server (NTRS)

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.

Pasion, A. J.

1979-01-01

35

A search for the Mpemba effect: When hot water freezes faster then cold water  

Microsoft Academic Search

An explanation for why hot water will sometime freeze more rapidly than cold\\u000awater is offered. Two specimens of water from the same source will often have\\u000adifferent spontaneous freezing temperatures; that is, the temperature at which\\u000afreezing begins. When both specimens supercool and the spontaneous freezing\\u000atemperature of the hot water is higher than that of the cold water,

James D. Brownridge

2010-01-01

36

FREEZING OP WATER IN W\\/O EMULSIONS  

Microsoft Academic Search

A short review is given on the freezing of water in w\\/o emulsions. First the state of supercooled water is discussed. The quantitative treatment of the liquid-solid phase transition in supercooled water is given by the homogeneous nucleation theory. From the experimental methods, which are used to study supercooled water, only few are applicable to the liquid-solid phase transition. From

Peter Brüggeller

1982-01-01

37

Standard Reference Material 1745: Indium Freezing-Point Standard and Standard Reference Material 2232: Indium DSC Melting-Point Standard.  

National Technical Information Service (NTIS)

The freezing point of indium (156.5985 degrees C) is a defining fixed-point cell containing high-purity (greater than or equal to 99.999% pure) indium. A single lot of indium (greater than or equal to 99.999% pure) constituting Standard Reference Material...

G. F. Strouse

2001-01-01

38

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

39

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

NASA Technical Reports Server (NTRS)

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.

Mathiprakasam, B.

1982-01-01

40

Freeze tolerance, supercooling points and ice formation: comparative studies on the subzero temperature survival of limno-terrestrial tardigrades.  

PubMed

Many limno-terrestrial tardigrades live in unstable habitats where they experience extreme environmental conditions such as drought, heat and subzero temperatures. Although their stress tolerance is often related only to the anhydrobiotic state, tardigrades can also be exposed to great daily temperature fluctuations without dehydration. Survival of subzero temperatures in an active state requires either the ability to tolerate the freezing of body water or mechanisms to decrease the freezing point. Considering freeze tolerance in tardigrades as a general feature, we studied the survival rate of nine tardigrade species originating from polar, temperate and tropical regions by cooling them at rates of 9, 7, 5, 3 and 1 degrees C h(-1) down to -30 degrees C then returning them to room temperature at 10 degrees C h(-1). The resulting moderate survival after fast and slow cooling rates and low survival after intermediate cooling rates may indicate the influence of a physical effect during fast cooling and the possibility that they are able to synthesize cryoprotectants during slow cooling. Differential scanning calorimetry of starved, fed and cold acclimatized individuals showed no intraspecific significant differences in supercooling points and ice formation. Although this might suggest that metabolic and biochemical preparation are non-essential prior to subzero temperature exposure, the increased survival rate with slower cooling rates gives evidence that tardigrades still use some kind of mechanism to protect their cellular structure from freezing injury without influencing the freezing temperature. These results expand our current understanding of freeze tolerance in tardigrades and will lead to a better understanding of their ability to survive subzero temperature conditions. PMID:19251996

Hengherr, S; Worland, M R; Reuner, A; Brümmer, F; Schill, R O

2009-03-01

41

Freezing and Melting Characteristics of a Sand Mold Containing Water on the Freeze Mold Method Process Using Cold Airflow  

NASA Astrophysics Data System (ADS)

This paper reports the freezing and melting characteristics of a sand mold containing water on the freeze mold method. In the freeze mold method, water in the cast sand is frozen and the sand mold becomes hard without caking additives. In this study, the sand mold was cooled by cold airflow for using the freeze mold method in practical applications. In the experiments, the sand containing water was filled into a rectangular container, and then cold air of -30°C was flowed into the container. After water in the sand was frozen, molten aluminum alloy of 900°C was cast into the sand mold to make a test piece. The freezing and melting behavior of water in the sand was investigated experimentally under the various water amount conditions. As a result, it was found that water of 1 mass% in the sand was evaporated by the cold airflow in the freezing process. In the casting process, the movement of evaporation interface becomes slow as the water amount in the sand increases, on the other hand, the movement of melting interface is not influenced by the water amount so much.

Horibe, Akihiko; Inaba, Hideo; Haruki, Naoto; Miyagawa, Yasunori

42

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

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

43

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

PubMed

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

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

2014-04-01

44

A Holistic Description of Immersion Freezing of Water and Aqueous Solution Droplets Using a Water Activity Based Model  

NASA Astrophysics Data System (ADS)

Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation in the atmosphere where it results in the glaciation of mixed-phase and cirrus clouds. Using a variety of IN types suspended in various aqueous solutions and pure water, we find that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, aw, which is the ratio of the vapor pressure of the solution and the saturation water vapor pressure under the same conditions and, in equilibrium, is equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result termed the aw based immersion freezing model (ABIFM). This method is independent of the nature of the solute, applicable for pure water droplet freezing which is significant for mixed-phase cloud formation, and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing capable of predicting of freezing temperatures, Jhet, frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas and cooling rates of droplets containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as IN surface area increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The experimental data implicitly questions the common notion that one active site initiates the formation of an ice embryo leading to the crystallization of the aqueous phase. The log10(Jhet) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total IN surface area, and cloud activation timescales typical of atmospheric conditions. Lastly, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions.

Knopf, D. A.; Alpert, P. A.

2013-12-01

45

When does hot water freeze faster then cold water? A search for the Mpemba effect  

NASA Astrophysics Data System (ADS)

It is possible to consistently observe hot water freezing faster than cold water under certain conditions. All conditions except the initial temperature of water specimens must be the same and remain so during cooling, and the cold water must supercool to a temperature significantly lower than the temperature to which the hot water supercools. For hot water at an initial temperature of >~80 °C and cold water at <~20 °C, the cold water must supercool to a temperature of at least ~5.5 °C, lower than the temperature to which hot water supercools. With these conditions satisfied, we observed initially hot water freezing before the initially cold water 28 times in 28 attempts. If the cold water does not supercool, it will freeze before the hot water because it always cools to 0 °C first regardless of the initial temperatures.

Brownridge, James D.

2011-01-01

46

Measurement of the in freezing-point temperature: Effect of the liquid-solid interface structure  

NASA Astrophysics Data System (ADS)

The results of the experimental study of the inner interface formation process under different conditions of its initiation for the indium freezing point showed that, depending on the initiation intensity, both the planar structure of the interface on the thermometer well and a noticeable intergrowth of dendrites could be obtained. However, under some specific initiation conditions dendrites disappeared partly or completely in the process of crystallization. The value of the indium freezing point temperature was measured under realization conditions corresponding to different inner interface structure.

Ivanova, A. G.; Abasov, M. Yu.; Gerasimov, S. F.; Pokhodun, A. I.

2013-09-01

47

When does hot water freeze faster then cold water? A search for the Mpemba effect  

Microsoft Academic Search

It is possible to consistently observe hot water freezing faster than cold water under certain conditions. All conditions except the initial temperature of water specimens must be the same and remain so during cooling, and the cold water must supercool to a temperature significantly lower than the temperature to which the hot water supercools. For hot water at an initial

James D. Brownridge

2011-01-01

48

Heterogeneous freezing of water droplets containing kaolinite particles  

NASA Astrophysics Data System (ADS)

Clouds composed of both ice particles and supercooled liquid water droplets exist at temperatures above ~236 K. These mixed phase clouds, which strongly impact climate, are very sensitive to the presence of solid particles that can catalyse freezing. In this paper we describe experiments to determine the conditions at which the clay mineral kaolinite nucleates ice when immersed within water droplets. These are the first immersion mode experiments in which the ice nucleating ability of kaolinite has been determined as a function of clay surface area, cooling rate and also at constant temperatures. Water droplets containing a known amount of clay mineral were supported on a hydrophobic surface and cooled at rates of between 0.8 and 10 K min-1 or held at constant sub-zero temperatures. The time and temperature at which individual 10-50 ?m diameter droplets froze were determined by optical microscopy. For a cooling rate of 10 K min-1, the median nucleation temperature of 10-40 ?m diameter droplets increased from close to the homogeneous nucleation limit (236 K) to 240.8 ± 0.6 K as the concentration of kaolinite in the droplets was increased from 0.005 wt% to 1 wt%. This data shows that the probability of freezing scales with surface area of the kaolinite inclusions. We also show that at a constant temperature the number of liquid droplets decreases exponentially as they freeze over time. The constant cooling rate experiments are consistent with the stochastic, singular and modified singular descriptions of heterogeneous nucleation; however, freezing during cooling and at constant temperature can be reconciled best with the stochastic approach. We report temperature dependent nucleation rate coefficients (nucleation events per unit time per unit area) for kaolinite and present a general parameterisation for immersion nucleation which may be suitable for cloud modelling once nucleation by other important ice nucleating species is quantified in the future.

Murray, B. J.; Broadley, S. L.; Wilson, T. W.; Atkinson, J. D.; Wills, R. H.

2011-05-01

49

Thermodynamic temperature measurements of silver freezing point and HTFPs  

NASA Astrophysics Data System (ADS)

The hybrid method, by introducing a lens to the irradiance method, was adopted to measure the thermodynamic temperature at NIM. An absolute radiation thermometer was established with two alternative filter radiometers (633nm and 900nm). The parameters of the absolute radiation thermometer were calibrated. The thermodynamic temperatures of the silver fixed point and Co-C, Pt-C, Re-C were determined. The uncertainties were 0.24K to 0.94K for FR633 and 0.34K to 1.6K for FR900 from the silver point to Re-C. The results were compared with the ITS-90 values and show a good agreement: 0.18K at Co-C, -0.11K at Pt-C and -0.24K at Re-C, which are under the estimated uncertainties.

Yuan, Z.; Lu, X.; Hao, X.; Dong, W.; Wang, T.; Lin, Y.; Wang, J.; Duan, Y.

2013-09-01

50

Deformation mechanism of nanoporous materials upon water freezing and melting  

NASA Astrophysics Data System (ADS)

Temperature-induced non-monotonous reversible deformation of water-filled nanoporous silica materials is investigated experimentally using in-situ small-angle x-ray scattering. The influence of freezing and melting in the nanopores on this deformation is treated quantitatively by introducing a simple model based on the Gibbs-Thomson equation and a generalized Laplace-pressure. The physical origin of the melting/freezing induced pore lattice deformation is found to be exactly the same as for capillary condensation/evaporation, namely the curved phase boundary due to the preferred wetting of the pore walls by the liquid phase. As a practical implication, elastic properties of the nanoporous framework can be determined from the temperature-deformation curves.

Erko, Maxim; Wallacher, Dirk; Paris, Oskar

2012-10-01

51

Promising freeze protection alternatives in solar domestic hot water systems  

SciTech Connect

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 resorting to a heat exchanger. Commonly, collectors are made of rigid copper tubes separated by copper or aluminum fins. Cracking damage can occur when water is allowed to freeze and expand inside the non compliant tubes. The possibility of making collectors out of an elastic material was investigated and shown to be effective. Since unlike copper, elastomers typically have low thermal conductivities, the standard collector performance prediction equations do not apply. Modified thermal performance prediction equations were developed which can be used for both low and high thermal conductivity materials to provide accurate predictions within a limited range of plate geometries. An elastomeric collector plate was then designed and shown to have comparable performance to a copper plate collector whose aperture area is approximately 33% smaller. Another options for providing freeze protection to an SDHW system is to turn it off during the winter. Choosing a three-season operating period means two things. First, the system will have different optimums such as slope and collector area. Second, the wintertime solar energy incident on the collector is unavailable for meeting a heating load. However, the system`s heat exchanger becomes unnecessary and removing it increases the amount of energy that arrives at the storage tank during those periods in which the system is operating.

Bradley, D.E.

1997-12-31

52

Metabolic Activity of Permafrost Bacteria below the Freezing Point  

PubMed Central

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.

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

2000-01-01

53

A water activity based model of heterogeneous ice nucleation kinetics for freezing of water and aqueous solution droplets.  

PubMed

Immersion freezing of water and aqueous solutions by particles acting as ice nuclei (IN) is a common process of heterogeneous ice nucleation which occurs in many environments, especially in the atmosphere where it results in the glaciation of clouds. Here we experimentally show, using a variety of IN types suspended in various aqueous solutions, that immersion freezing temperatures and kinetics can be described solely by temperature, T, and solution water activity, a(w), which is the ratio of the vapour pressure of the solution and the saturation water vapour pressure under the same conditions and, in equilibrium, equivalent to relative humidity (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, J(het), to be uniquely expressed by T and a(w), a result we term the a(w) based immersion freezing model (ABIFM). This method is independent of the nature of the solute and accounts for several varying parameters, including cooling rate and IN surface area, while providing a holistic description of immersion freezing and allowing prediction of freezing temperatures, J(het), frozen fractions, ice particle production rates and numbers. Our findings are based on experimental freezing data collected for various IN surface areas, A, and cooling rates, r, of droplets variously containing marine biogenic material, two soil humic acids, four mineral dusts, and one organic monolayer acting as IN. For all investigated IN types we demonstrate that droplet freezing temperatures increase as A increases. Similarly, droplet freezing temperatures increase as the cooling rate decreases. The log10(J(het)) values for the various IN types derived exclusively by Tand a(w), provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Lastly, we demonstrate that ABIFM can be used to derive frozen fractions of droplets and ice particle production for atmospheric models of cirrus and mixed phase cloud conditions. PMID:24601020

Knopf, Daniel A; Alpert, Peter A

2013-01-01

54

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

55

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

PubMed Central

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.

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

1969-01-01

56

Universal behavior of repulsive two-dimensional fermions in the vicinity of the quantum freezing point  

NASA Astrophysics Data System (ADS)

We show by a meta-analysis of the available Quantum Monte Carlo (QMC) results that two-dimensional fermions with repulsive interactions exhibit universal behavior in the strongly correlated regime, and that their freezing transition can be described using a quantum generalization of the classical Hansen-Verlet freezing criterion. We calculate the liquid-state energy and the freezing point of the 2D dipolar Fermi gas (2DDFG) using a variational method by taking ground-state wave functions of 2D electron gas (2DEG) as trial states. A comparison with the recent fixed-node diffusion Monte Carlo analysis of the 2DDFG shows that our simple variational technique captures more than 95% of the correlation energy, and predicts the freezing transition within the uncertainty bounds of QMC. Finally, we utilize the ground-state wave functions of 2DDFG as trial states and provide a variational account of the effects of finite 2D confinement width. Our results indicate significant beyond mean-field effects. We calculate the frequency of collective monopole oscillations of the quasi-2D dipolar gas as an experimental demonstration of correlation effects.

Babadi, Mehrtash; Skinner, Brian; Fogler, Michael M.; Demler, Eugene

2013-07-01

57

Bovine serum albumin: survival and osmolarity effect in bovine spermatozoa stored above freezing point.  

PubMed

Liquid nitrogen preservation in remote farms is a limitation. The goal of this study was to determine optimum temperature above freezing point for bovine spermatozoa preservation using bovine serum albumin (BSA) as a supplementation. Pooled semen sample from three ejaculates was subjected to various BSA concentration (1, 4, 8 and 12 mg ml(-1)), before incubation in different above freezing point temperatures (4, 25 and 37 °C). Viability assessment was carried out against time from day 0 (fresh sample) until all spermatozoa become nonviable. Optimal condition for bovine spermatozoa storage was at 4 °C with 1 mg ml(-1) BSA for almost 7 days. BSA improved bovine spermatozoa viability declining rate to 44.28% at day 4 and 57.59% at day 7 compared to control, with 80.54% and 98.57% at day 4 and 7 respectively. Increase in BSA concentration did not improve sperm viability. Our results also confirmed that there was a strong negative correlation between media osmolarity and bovine spermatozoa survival rate with r = 0.885, P < 0.0001. Bovine serum albumin helps to improve survival rate of bovine spermatozoa stored above freezing point. PMID:21806660

Nang, C F; Osman, K; Budin, S B; Ismail, M I; Jaffar, F H F; Mohamad, S F S; Ibrahim, S F

2012-05-01

58

Effect of nanoscale confinement on freezing of modified water at room temperature and ambient pressure.  

PubMed

Understanding the phase behavior of confined water is central to fields as diverse as heterogeneous catalysis, corrosion, nanofluidics, and to emerging energy technologies. Altering the state points (temperature, pressure, etc.) or introduction of a foreign surface can result in the phase transformation of water. At room temperature, ice nucleation is a very rare event and extremely high pressures in the GPa-TPa range are required to freeze water. Here, we perform computer experiments to artificially alter the balance between electrostatic and dispersion interactions between water molecules, and demonstrate nucleation and growth of ice at room temperature in a nanoconfined environment. Local perturbations in dispersive and electrostatic interactions near the surface are shown to provide the seed for nucleation (nucleation sites), which lead to room temperature liquid-solid phase transition of confined water. Crystallization of water occurs over several tens of nanometers and is shown to be independent of the nature of the substrate (hydrophilic oxide vs. hydrophobic graphene and crystalline oxide vs. amorphous diamond-like carbon). Our results lead us to hypothesize that the freezing transition of confined water can be controlled by tuning the relative dispersive and electrostatic interaction. PMID:24715572

Deshmukh, Sanket; Kamath, Ganesh; Sankaranarayanan, Subramanian K R S

2014-06-01

59

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

NASA Astrophysics Data System (ADS)

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).

Bogorodsky, Petr; Marchenko, Aleksey

2014-05-01

60

Separation of water and oil from water-in-oil emulsion by freeze\\/thaw method  

Microsoft Academic Search

The oily sludge generated from the pretreatment step of the used lubricating oil re-refinery is characterized as a complex and tight water\\/oil emulsion with water content varying from 38 to 77 wt.%. Removal of water is necessary for the emulsion to be fed into the processing line. Freeze\\/thaw method proves to be effective, with near 90% of water removed. An

Guohua Chen; Gaohong He

2003-01-01

61

Soil water content and freezing temperature affect freeze–thaw related N 2 O production in organic soil  

Microsoft Academic Search

An organic agricultural soil was exposed to freeze–thaw cycles (FTC) using either intact soil cores or cores packed with homogenized soil. The cores were first exposed to two mild FTCs (–1.5?°C\\/+4?°C) with soil water content being 56–85% of the water-filled pore space (WFPS). Both intact and packed soil cores showed high N2O emissions when the soil was thawing and had

Hannu T. Koponen; Pertti J. Martikainen

2004-01-01

62

Practical limitations of ITS-90 from the mercury triple point to the silver freeze point  

SciTech Connect

The NPL published a forward to the ITS-90 text as follows:- 'The purpose of the ITS is to define procedures by which certain specified practical thermometers of the required quality can be calibrated in such a way that the values of temperature obtained from them can be precise and reproducible, while at the same time closely approximating the corresponding thermodynamic values.' [1]. The paper investigates the properties of thirty four lots of 6N pure metal used to make cells conforming to ITS-90 from mercury through silver over a period of twenty years. Three hundred individual cells are analysed by the impurities listed and supplied with each lot, melt and freeze curve slopes are also summarised for each lot and depressions calculated. These are then compared to the slopes and depressions suggested in the Supplementary Information for the ITS-90 and in CCT/2000-13 'Optimal Realizations'. Results are summarised, tabulated and discussed. Three lots of the thirty four were found to produce cells outside 6N expectations; however the remaining thirty one lots no matter how well or badly the accompanying certification was presented produced cells that conformed to 6N expectations as suggested in Supplementary Information to ITS-90 and CCT/2000-13.

Tavener, J. P.; Tavener, S. J.; Tavener, I. F.; Davies, N. [Isothermal Technology Ltd (Isotech), Pine Grove, Southport, Merseyside, PR9 9AG, England (United Kingdom)] [Isothermal Technology Ltd (Isotech), Pine Grove, Southport, Merseyside, PR9 9AG, England (United Kingdom)

2013-09-11

63

Practical limitations of ITS-90 from the mercury triple point to the silver freeze point  

NASA Astrophysics Data System (ADS)

The NPL published a forward to the ITS-90 text as follows:- "The purpose of the ITS is to define procedures by which certain specified practical thermometers of the required quality can be calibrated in such a way that the values of temperature obtained from them can be precise and reproducible, while at the same time closely approximating the corresponding thermodynamic values." [1]. The paper investigates the properties of thirty four lots of 6N pure metal used to make cells conforming to ITS-90 from mercury through silver over a period of twenty years. Three hundred individual cells are analysed by the impurities listed and supplied with each lot, melt and freeze curve slopes are also summarised for each lot and depressions calculated. These are then compared to the slopes and depressions suggested in the Supplementary Information for the ITS-90 and in CCT/2000-13 "Optimal Realizations". Results are summarised, tabulated and discussed. Three lots of the thirty four were found to produce cells outside 6N expectations; however the remaining thirty one lots no matter how well or badly the accompanying certification was presented produced cells that conformed to 6N expectations as suggested in Supplementary Information to ITS-90 and CCT/2000-13.

Tavener, J. P.; Tavener, S. J.; Tavener, I. F.; Davies, N.

2013-09-01

64

Ultra-high temperature isothermal furnace liners (IFLS) for copper freeze point cells  

NASA Astrophysics Data System (ADS)

Primary Laboratories use large fixed-point cells in deep calibration furnaces utilizing heat pipes to achieve temperature uniformity. This combination of furnace, heat pipe, and cell gives the smallest of uncertainties. The heat pipe, also known as an isothermal furnace liner (IFL), has typically been manufactured with Alloy 600/601 as the envelope material since the introduction of high temperature IFLs over 40 years ago. Alloy 600/601 is a widely available high temperature material, which is compatible with Cesium, Potassium, and Sodium and has adequate oxidation resistance and reasonable high temperature strength. Advanced Cooling Technologies, Inc. (ACT) Alloy 600/Sodium IFLs are rated to 1100°C for approximately 1000 hours of operation (based on creep strength). Laboratories interested in performing calibrations and studies around the copper freezing point (1084.62°C) were frustrated by the 1000 hours at 1100°C limitation and the fact that expensive freeze-point cells were getting stuck and/or crushed inside the IFL. Because of this growing frustration/need, ACT developed an Ultra High Temperature IFL to take advantage of the exceptional high temperature strength properties of Haynes 230.

Dussinger, P. M.; Tavener, J. P.

2013-09-01

65

Improvements in the realization of the ITS-90 over the temperature range from the melting point of gallium to the freezing point of silver at NIM  

SciTech Connect

The temperature primary standard over the range from the melting point of gallium to the freezing point of silver in National institute of Metrology (NIM), China, was established in the early 1990s. The performance of all of fixed-point furnaces degraded and needs to be updated due to many years of use. Nowadays, the satisfactory fixed point materials can be available with the development of the modern purification techniques. NIM plans to use a group of three cells for each defining fixed point temperature. In this way the eventual drift of individual cells can be evidenced by periodic intercomparison and this will increase the reliability in disseminating the ITS-90 in China. This article describes the recent improvements in realization of ITS-90 over temperature range from the melting point of gallium to the freezing point of silver at NIM. Taking advantages of the technological advances in the design and manufacture of furnaces, the new three-zone furnaces and the open-type fixed points were developed from the freezing point of indium to the freezing point of silver, and a furnace with the three-zone semiconductor cooling was designed to automatically realize the melting point of gallium. The reproducibility of the new melting point of gallium and the new open-type freezing points of In, Sn, Zn. Al and Ag is improved, especially the freezing points of Al and Ag with the reproducibility of 0.2mK and 0.5mK respectively. The expanded uncertainty in the realization of these defining fixed point temperatures is 0.34mK, 0.44mK, 0.54mK, 0.60mK, 1.30mK and 1.88mK respectively.

Sun, J.; Zhang, J. T.; Ping, Q. [National institute of Metrology, Beijing (China)] [National institute of Metrology, Beijing (China)

2013-09-11

66

Improvements in the realization of the ITS-90 over the temperature range from the melting point of gallium to the freezing point of silver at NIM  

NASA Astrophysics Data System (ADS)

The temperature primary standard over the range from the melting point of gallium to the freezing point of silver in National institute of Metrology (NIM), China, was established in the early 1990s. The performance of all of fixed-point furnaces degraded and needs to be updated due to many years of use. Nowadays, the satisfactory fixed point materials can be available with the development of the modern purification techniques. NIM plans to use a group of three cells for each defining fixed point temperature. In this way the eventual drift of individual cells can be evidenced by periodic intercomparison and this will increase the reliability in disseminating the ITS-90 in China. This article describes the recent improvements in realization of ITS-90 over temperature range from the melting point of gallium to the freezing point of silver at NIM. Taking advantages of the technological advances in the design and manufacture of furnaces, the new three-zone furnaces and the open-type fixed points were developed from the freezing point of indium to the freezing point of silver, and a furnace with the three-zone semiconductor cooling was designed to automatically realize the melting point of gallium. The reproducibility of the new melting point of gallium and the new open-type freezing points of In, Sn, Zn. Al and Ag is improved, especially the freezing points of Al and Ag with the reproducibility of 0.2mK and 0.5mK respectively. The expanded uncertainty in the realization of these defining fixed point temperatures is 0.34mK, 0.44mK, 0.54mK, 0.60mK, 1.30mK and 1.88mK respectively.

Sun, J.; Zhang, J. T.; Ping, Q.

2013-09-01

67

Measurement of water and solute dynamics in freezing soil columns with time domain reflectometry  

Microsoft Academic Search

Two soil columns (Davos sand, Alptal loam) were subjected to a cycle of one-dimensional freezing and thawing from both ends towards the middle of the columns. The freezing characteristic curves were determined at different levels in the columns and used to estimate parameters in a physically based mathematical model. Measurements of liquid soil water content with time domain reflectometry (TDR)

Manfied Stähli; Daniel Stadler

1997-01-01

68

Delayed freezing of water droplet on silver nanocolumnar thin film  

NASA Astrophysics Data System (ADS)

Silver nanocolumns were grown on Si substrate using glancing angle deposition method. Interestingly, the cold nanocolumnar surface was observed to make a delay of more than 62 s in freezing compared to the conventional silver thin film. The observed delay in freezing on silver nanocolumns is explainable in terms of reduction in effective liquid-solid interface area within the framework of Cassie-Baxter model. This study shows the possibility of using silver nanocolumnar films in ice free coatings and surfaces with tunable freezing properties.

Singh, Dhruv P.; Singh, Jitendra P.

2013-06-01

69

Early Mars was wet but not warm: Erosion, fluvial features, liquid water habitats, and life below freezing  

NASA Technical Reports Server (NTRS)

There is considerable evidence that Mars had liquid water early in its history and possibly at recurrent interval. It has generally been assumed that this implied that the climate was warmer as a result of a thicker CO2 atmosphere than at the present. However, recent models suggest that Mars may have had a thick atmosphere but may not have experienced mean annual temperatures above freezing. In this paper we report on models of liquid water formation and maintenance under temperatures well below freezing. Our studies are based on work in the north and south polar regions of Earth. Our results suggest that early Mars did have a thick atmosphere but precipitation and hence erosion was rare. Transient liquid water, formed under temperature extremes and maintained under thick ice covers, could account for the observed fluvial features. The main difference between the present climate and the early climate was that the total surface pressure was well above the triple point of water.

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

1993-01-01

70

Early Mars was wet but not warm: Erosion, fluvial features, liquid water habitats, and life below freezing  

NASA Astrophysics Data System (ADS)

There is considerable evidence that Mars had liquid water early in its history and possibly at recurrent interval. It has generally been assumed that this implied that the climate was warmer as a result of a thicker CO2 atmosphere than at the present. However, recent models suggest that Mars may have had a thick atmosphere but may not have experienced mean annual temperatures above freezing. In this paper we report on models of liquid water formation and maintenance under temperatures well below freezing. Our studies are based on work in the north and south polar regions of Earth. Our results suggest that early Mars did have a thick atmosphere but precipitation and hence erosion was rare. Transient liquid water, formed under temperature extremes and maintained under thick ice covers, could account for the observed fluvial features. The main difference between the present climate and the early climate was that the total surface pressure was well above the triple point of water.

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

71

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

PubMed

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

Niwa, Toshiyuki; Mizutani, Daisuke; Danjo, Kazumi

2012-01-01

72

Researches of optical cable stability in the microduct to effect of freezing water  

NASA Astrophysics Data System (ADS)

In article results of experimental researches of optical cable behavior in microducts at water freezing are presented. Researches were carried out with the polymeric and steel microducts. Researches have shown that loadings which influence on a cable at water freezing in the steel microduct is higher than in polymeric and can lead to attenuation increase in the optical fiber. In the polymeric duct loadings more low, than in the steel. However if a polymeric microduct freeze in ice, pressure upon a cable as can cause an incrementation of attenuation.

Burdin, Vladimir A.; Nikulina, Tatiana G.; Alekhin, Ivan N.; Gavryushin, Sergey A.

2010-12-01

73

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

Microsoft Academic Search

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

Joe Wolfe; Gary Bryant

1999-01-01

74

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

Microsoft Academic Search

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

Trahern

1989-01-01

75

Water Freezes Differently on Positively and Negatively Charged Surfaces of Pyroelectric Materials  

NASA Astrophysics Data System (ADS)

Although ice melts and water freezes under equilibrium conditions at 0°C, water can be supercooled under homogeneous conditions in a clean environment down to -40°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°C freeze immediately when this surface is heated to -8°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.

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

2010-02-01

76

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

PubMed

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

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

2010-02-01

77

Coupled water and heat flow in a grass field with aggregated Andisol during soil-freezing periods  

Microsoft Academic Search

During soil-freezing periods, coupled water and heat flow is important for predicting frost depth and unsaturated water flow between frozen and unfrozen soil. We investigated water and heat flow in Andisol with aggregated soil structure at a grass field during soil-freezing periods. The water retention curve (WRC) had a stepwise shape, in which water content, ?, decreased drastically at air

Ieyasu Tokumoto; Kosuke Noborio; Kiyoshi Koga

2010-01-01

78

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

SciTech Connect

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.

Trahern, P.G.

1989-01-01

79

Experimental study on the effect of the electric filed on the freezing of the supercooled water  

NASA Astrophysics Data System (ADS)

Effect of the electric field on freezing of supercooled water was investigated, experimentally. The experiment was carried out by charging the electrode whose tip was inserted into supercooled water. It was found that supercooled water freeze instantly by applying the electric charge. There were many papers in the past which dealt with the effect of electrical field on freezing of supercooled water, but with a high voltage, order of a few kV. However, through this experimental study, it was found that the supercooled water can freeze at the voltage less than 100V, if D.C. voltage is applied directly to supercooled water. There was no deformation of water droplet or spark discharge as some papers suggest as a reason for the effect. It was also found that the probability of freezing depends upon the degree of supercooling, value of D.C. voltage applied, size of electrode and the distance between two electrods. The mechanism of this effect was discussed and suggested as follows: High electric field is formed locally due to the existence of surface edge or small projections on the surface. Water molecule which has a polarity is drawn near to the cluster on the surface whose motion is restricted by the existence of electric field. Therefore, embryo can transform to nucleus, instantly.

Okawa, Seiji; Saito, Akio; Harada, Tadahide

80

Three-dimensional freezing of water in a copper foils porous layer around a coolant-carrying tube  

NASA Astrophysics Data System (ADS)

Three-dimensional freezing of water around a coolant carrying horizontal tube placed in an adiabatic rectangular cavity partially including copper foils is investigated numerically and by experiment. Both, enhancement of freezing and a uniform freezing rate are achieved. The present numerical analysis predicts well the transient solid fraction found by experiments.

Sugawara, M.; Komatsu, Y.; Onodera, D.; Beer, H.

2012-11-01

81

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

Microsoft Academic Search

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

B. Norton; J. E. J. Edmonds

1991-01-01

82

Effect of natural convection on freezing of water around an isothermal, horizontal cylinder  

SciTech Connect

Freezing of superheated water around an isothermal, horizontal cylinder has been studied experimentally. The shadowgraph technique was used to visualize the flow (plume) development in the water, and the contour of the ice layer around the heat sink was recorded photographically. Freezing of water was always accompanied by natural convection and produced nonuniform ice growth. Benard-Goertler instabilities resulted in secondary flows which produced waviness (nonuniform) ice growth along the axis of the cylinder. The number, location and magnitude of the ripples were found to depend on the initial water superheat and on the heat sink temperature.

Herrmann, J.; Leidenfrost, W.; Viskanta, R.

1984-07-01

83

Freeze-drying of tertiary butyl alcohol\\/water cosolvent systems  

Microsoft Academic Search

The objective of this study was to identify significant formulation and processing variables affecting levels of tert-butyl alcohol (TBA) and isopropyl alcohol (IPA) in freeze-dried solids prepared from TBA\\/water cosolvent systems. The TBA concentration above which eutectic crystallization takes place was determined by differential scanning calorimetry. Model formulations were subjected to extremes of freezing rate by either dipping in liquid

Sakchai Wittaya-areekul

1999-01-01

84

Droplet freezing experiments in stearic acid-water emulsions, role of the droplet-medium interface  

SciTech Connect

Droplets of stearic acid emulsions in water, stabilized with cationic or anionic emulsifiers, undergoing freezing-melting cycles with constant temperature scanning rate, freeze as monocrystals and independently from one another, even when visible clustering takes place. The study of the nucleation kinetics by differential scanning calorimetry shows that nucleation threshold (critical undercooling) depends on the nature of the emulsifier, adsorbed at the droplet-medium interface. 30 references.

Cordiez, J.P.; Grange, G.; Mutaftschiev, B.

1982-02-01

85

A study on freeze–thaw characteristics and microstructure of Chinese water chestnut starch gels  

Microsoft Academic Search

The influence of the repeatedly freeze-thawed (FT) treatment on the microstructure, crystallinity, thermal properties, textural properties and resistant starch content of Chinese water chestnut starch (CWCS) gels were investigated, using scanning electron microscopy (SEM), X-ray diffractometry, differential scanning calorimetry (DSC) and textural analysis (TA). The microstructure of the native starch gel was a compact and random phase. Freeze-thawed starch gels

Lan Wang; Zhihua Yin; Jia Wu; Zhida Sun; Bijun Xie

2008-01-01

86

SUPPLEMENTARY COMPARISON: Final report of EUROMET.TS2 (projects EUROMET 391 and 712): Supplementary comparison of realizations of the indium freezing point  

Microsoft Academic Search

Comparisons of indium freezing point cells have been carried out by the EUROMET TC-THERM group as Projects Nos 391 and 712. The main objective was to establish the agreement between the realizations of the indium freezing point within different participating laboratories, to identify and eliminate possible discrepancies. The equipment has been made available by BNM-INM. Justervesenet coordinated project no 391,

C. Rauta; E. Renaot; M. H. Valin; M. Elgourdou; F. Adunka; A. van der Linden; A. Steiner; J. Bartu; M. Smid; M. Sindelar; E. Tegeler; Ute Noatsch; J.-U. Holtoug; V. Chimenti; M. Anagnostou; T. Weckstrøm; G. Sutton; R. Rusby; F. Pavese; P. P. M. Steur; P. Marcarino; M. J. de Groot; E. Filipe; I. Lobo; J. Ivarsson; S. Duris; J. Bojkovski; Miha Hiti; S. Ugur; A. K. Dogan; E. Grudniewicz

2008-01-01

87

In situ freeze-capturing of fracture water using cryogenic coring  

SciTech Connect

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.

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

2004-01-29

88

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

89

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

SciTech Connect

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.

Hayashi, K.; Kasza, K.

2000-05-03

90

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

91

Avoid freeze-up of steam traps and their piping  

Microsoft Academic Search

This article addresses the problem of keeping steam traps free of ice in cold weather. The topics of the article include piping configurations and trap types that contribute to freezing, freeze damage, obstructions in piping, insulation of lines to retard freezing, common manifolds for heating of condensate, draining of low points, temperature-actuated devices, and water hammer damage.

OKeefe

1993-01-01

92

Solutions : FreezePtDepression (20 Variations)  

NSDL National Science Digital Library

It takes 6.86 kg of ethylene glycol (antifreeze) to decrease the freezing point of 6.50 kg of water to -25.0 o F (-31.7 o C). How much sodium chloride (NaCl) would it take to decrease the freezing point of 6.50 kg of water to -25.0 o F? (Assuming all the salt will dissolve in that amount of water.)

93

Freezing lake  

NSDL National Science Digital Library

Finite difference solution to mixed conduction-convection limited freezing of a 10 cm thick pool of water, with benchmark against analytical timescales. Requisite software: Gnumeric or Excel to open spreadsheets in source directory.

Powell, Adam C., IV

2005-02-23

94

Nanosecond freezing of water under multiple shock wave compression: Continuum modeling and wave profile measurements  

NASA Astrophysics Data System (ADS)

Using real time optical transmission and imaging measurements in multiple shock wave compression experiments, water was shown to solidify on nanosecond time scales [D. H. Dolan and Y. M. Gupta, J. Chem. Phys. 121, 9050 (2004)]. Continuum modeling and wave profile measurements, presented here, provide a complementary approach to examine the freezing of shocked water. The water model consisted of thermodynamically consistent descriptions of liquid and solid (ice VII) water, relationships for phase coexistence, and a time-dependent transition description to simulate freezing dynamics. Continuum calculations using the water model demonstrate that, unlike single shock compression, multiple shock compression results in pressure-temperature conditions where the ice VIII phase is thermodynamically favored over the liquid phase. Wave profile measurements, using laser interferometry, were obtained with quartz and sapphire windows at a peak pressure of 5 GPa. For water confined between sapphire windows, numerical simulations corresponding to a purely liquid response are in excellent agreement with the measured wave profile. For water confined between quartz windows (to provide a nucleating surface), wave profile measurements demonstrate a pure liquid response for an incubation time of approximately 100 ns followed by a time-dependent transformation. Analysis of the wave profiles after the onset of transformation suggests that water changes from a metastable liquid to a denser phase, consistent with the formation of a high-pressure ice phase. Continuum analyses and simulations underscore the need for multiple time scales to model the freezing transition. Findings from the present continuum work are extremely consistent with optical results reported previously. These studies constitute the first comprehensive investigation reported for freezing of a liquid at very short time scales.

Dolan, D. H.; Johnson, J. N.; Gupta, Y. M.

2005-08-01

95

Effect of oil phase transition on freeze/thaw-induced demulsification of water-in-oil emulsions.  

PubMed

Recently, there has been an increasing interest in the breakage of water-in-oil (W/O) emulsions by the freeze/thaw method. Most of the previous works focused on the phase transition of the water droplet phase. This paper emphasizes the effect of continuous oil phase transition. A series of oils with different freezing points were used as oil phases to produce model emulsions, which were then frozen and thawed. The emulsion whose oil phase froze before the water droplet phase did (OFBW) on cooling was readily demulsified with a dewatering ratio as high as over 80%, but the emulsion whose oil phase did not freeze when the water droplet phase did (NOFBW) was relatively hard to break. The difference in demulsification performance between them resulted from the distinction between their demulsification mechanisms via the analyses of the emulsion stability, emulsion crystallization/melting behaviors, oil phase physical properties, and wettability of the frozen oil phase, etc. For the OFBW emulsion, the first-frozen oil phase was ruptured by the volume expansion of the subsequently frozen droplet phase, and meanwhile, some liquid droplet phase was drawn into the fine gaps/crevices of the frozen oil phase to bridge droplets, which were considered to be essential to the emulsion breakage, whereas for the NOFBW emulsion, the demulsification was attributed to the collision mechanism proposed in our previous work. The findings may provide some criteria for selecting a proper oil phase in the emulsion liquid membrane (ELM) process and then offer an alternative approach to recycle the oil phase for continuous operation. This work may also be useful for emulsion stability against temperature cycling. PMID:18433153

Lin, Chang; He, Gaohong; Dong, Chunxu; Liu, Hongjing; Xiao, Gongkui; Liu, YuanFa

2008-05-20

96

Freezing Characteristics of Layered Air-Water Flow in a Horizontal Circular Tube  

NASA Astrophysics Data System (ADS)

An experimental study has been performed to investigate characteristics of the freezing heat transfer of layered air-water flow in a circular tube, in which cooled air and water co-flow. The experiments were carried out under a variety of conditions of water discharge, water temperature, tube-wall temperature, air discharge, and water level. Particular attention was focused on photographic visual observations of the developing ice layer along the tube wall. It was in general observed that there were two different regions characterizing the ice formation, one of which was the freeze-off region, and the other was the steady-state region. The onset of freeze-off was found to be predicted by the equation Fo=1.85Rew0.142Rea-0.03?c-1.01(H/D)1.31. It was also found that the mean Nusselt number might be described as the following equation : Num=2.26×10-1Rew0.80Rea-0.03thetac-0.788(H/D)0.331.

Fukusako, Shoichiro; Takahashi, Masato

97

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

SciTech Connect

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, .

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

98

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...

99

A study of the freezing of supercooled water dispersed within emulsions by differential scanning calorimetry  

Microsoft Academic Search

Supercooling of microsize droplets of water dispersed within emulsions has been studied by means of a differential scanning calorimeter Perkin-Elmer DSC 2. In an emulsion cooled steadily at 2.5K min-1, the breakdown of supercooling in individual droplets is distributed in temperature over the range -37.5 degrees C to -40.5 degrees C, the most probable temperature of freezing being T*=-(39.0+or-0.5) degrees

F. Broto; D. Clausse

1976-01-01

100

Freezing of Water next to Solid Surfaces Probed Using Sum-Frequency Generation Spectroscopy  

NASA Astrophysics Data System (ADS)

The control of ice formation next to solid surfaces is important in many technological applications such as de-icing for aircrafts and generation of power using wind turbines. We have studied the water-ice transition next to sapphire surface to understand the freezing transition and nucleation of ice. The infrared-visible sum frequency generation spectroscopy is sensitive to the structure and orientation of water molecules next to the solid interface and provides direct information on transition kinetics at the interface. The differences in the nucleation kinetics will be discussed for water in contact with hydrophilic and hydrophobic surfaces.

Anim-Danso, Emmanuel; Kurian, Anish; Ge, Liehui; Alizadeh, Azar; Dhinojwala, Ali

2012-02-01

101

Freezing and Freeze-Drying  

Microsoft Academic Search

Most biological substances are unstable during storage owing to their high water content. This is why numerous attempts have been made over the last 100 years to prevent, by low temperature freezing, metabolic and biochemical degradations. The transformation of water into ice brings to an end all chemical reactions; however, it might also induce deleterious alterations into the delicate structure

L. Rey; N. W. Pirie; W. E. Whitman; N. Kurti

1975-01-01

102

Dynamic mechanical measurements on fresh-water ice during freezing and thawing: preliminary results  

NASA Astrophysics Data System (ADS)

An automated measurement system for elastic (J' ) and viscous (J'' ) components of complex shear compliance, J* = J' - iJ'', and the elastic (G' ) and viscous (G'' ) components of complex shear modulus, G* = G' + iG'' = 1/J*, has been used to obtain these material parameters for fresh-water ice during freezing and thawing. The system is reviewed briefly and yields mechanical loss tangents, J''/J' = G''/G', the shear-wave velocity and attenuation, in addition to shear compliance and modulus, at sinusoidal vibration frequencies from 2 to 10 000 Hz at temperatures between -25 and 150degreesC. Results reported here are chiefly at temperatures from 10 to -10degreesC. The required sample disk pairs, which are clamped to a central drive plate, are prepared outside the apparatus for solids and gels. Liquids of known volume are inserted between the drive plate and surrounding clamps at a separation distance, h, by a syringe to form sample disks of area, A = Volume / h. Measurements at 58 frequencies between 2 and 10 000 Hz require 3.5 min; several measurements at each temperature were made to test for equilibrium. Results for both tap and distilled water above freezing revealed high values of elastic (J' ) compliance that decreased sharply at 100 Hz and higher frequencies. Tap-water samples with 4 to 6% by volume air bubbles were less compliant ("stiffer") above freezing than samples with 0 to 1% by volume air, but when frozen, the samples with the smaller volume of air bubbles were less compliant, that is, had higher modulus values than the samples with high air-bubble volumes. Dynamic mechanical property changes in the transition from water to ice are compared to changes previously found during phase transitions in other materials. Further investigation on the effects of air-bubble volumes on dynamic mechanical properties of both water and ice is planned.

Fitzgerald, E. R.

2003-01-01

103

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

NSDL National Science Digital Library

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.

Aquarium, New E.

2011-01-01

104

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

NASA Technical Reports Server (NTRS)

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.

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

105

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

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

106

Experimental evidence of the ferroelectric nature of the ?-point transition in liquid water  

NASA Astrophysics Data System (ADS)

We studied the dielectric properties of nano-sized liquid water samples confined in polymerized silicates MCM-41 characterized by pore sizes 3-10 nm. Freezing temperature suppression in nanopores helps keep the water samples in liquid form at temperatures well below 0°C and thus effectively study the properties of supercooled liquid water. We report the first direct measurements of the dielectric constant by the dielectric spectroscopy method and demonstrate very clear signatures of the second-order phase transition of ferroelectric nature at temperatures next to the ?-point in the supercooled bulk water in full agreement with the recently developed model of the polar liquid.

Fedichev, P. O.; Menshikov, L. I.; Bordonskiy, G. S.; Orlov, A. O.

2011-11-01

107

Freezing and Melting  

NSDL National Science Digital Library

This article tells how the freezing point of a substance is also its melting point. The energy of the substance's molecules changes with temperature, thus with changes in state. Also described is how freezing points can be lowered, or depressed, by adding a substance.

2010-01-01

108

The stability against freezing of an internal liquid-water ocean in Callisto.  

PubMed

The discovery of the induced magnetic field of Callisto-one of Jupiter's moons-has been interpreted as evidence for a subsurface ocean, even though the presence of such an ocean is difficult to understand in the context of existing theoretical models. Tidal heating should not be significant for Callisto, and, in the absence of such heating, it is difficult to see how this internal ocean could have survived until today without freezing. Previous work indicated that an outer ice layer on the ocean would be unstable against solid-state convection, which once begun would lead to total freezing of liquid water in about 108 years. Here I show that when a methodology for more physically reasonable water ice viscosities (that is, stress-dependent non-newtonian viscosities, rather than the stress-independent newtonian viscosities considered previously) is adopted, the outer ice shell becomes stable against convection. This implies that a subsurface ocean could have survived up to the present, without the need for invoking antifreeze substances or other special conditions. PMID:11473308

Ruiz, J

2001-07-26

109

HybridICE® filter: ice separation in freeze desalination of mine waste waters.  

PubMed

Freeze desalination is an alternative method for the treatment of mine waste waters. HybridICE(®) technology is a freeze desalination process which generates ice slurry in surface scraper heat exchangers that use R404a as the primary refrigerant. Ice separation from the slurry takes place in the HybridICE filter, a cylindrical unit with a centrally mounted filter element. Principally, the filter module achieves separation of the ice through buoyancy force in a continuous process. The HybridICE filter is a new and economical means of separating ice from the slurry and requires no washing of ice with water. The performance of the filter at a flow-rate of 25 L/min was evaluated over time and with varied evaporating temperature of the refrigerant. Behaviours of the ice fraction and residence time were also investigated. The objective was to find ways to improve the performance of the filter. Results showed that filter performance can be improved by controlling the refrigerant evaporating temperature and eliminating overflow. PMID:24804655

Adeniyi, A; Maree, J P; Mbaya, R K K; Popoola, A P I; Mtombeni, T; Zvinowanda, C M

2014-01-01

110

Coagulation size of freezable water in poly(vinyl alcohol) hydrogels formed by different freeze\\/thaw cycle periods  

Microsoft Academic Search

The coagulation size of freezable water in a poly(vinyl alcohol) (PVA) hydrogel was investigated as a function of the freeze\\/thaw cycle period using thermal analysis. The melting temperature of ice in the gel shifted to a lower temperature than that of normal ice. This temperature depression can be interpreted in terms of the coagulation size of freezable water in the

Tatsuro Nakano; Takahiko Nakaoki

2011-01-01

111

Does Hot Water Freeze Faster than Cold? Investigation of the Reproducibility and Causes of the Mpemba Effect  

Microsoft Academic Search

An investigation into the reproducibility and possible causes of the Mpemba effect has been performed. The Mpemba effect is the name given to the common observation by non-scientists that hot water appears to freeze faster than cold water.^1 Previous scientific studies of this effect have found conflicting results. These discrepancies appear to be due in part to inconsistent definitions of

Joseph Thomas; Susan Lehman

2008-01-01

112

Towards a robust water content determination of freeze-dried samples by near-infrared spectroscopy.  

PubMed

The possibility for determination of the water content in pharmaceutical samples by near-infrared (NIR) spectroscopy has been more widely investigated in the past few years. However, many studies claim that changes in sample composition will require the establishment of a new method. The aim of this study was several fold: firstly to investigate validation aspects of water content determination in samples with varying composition and furthermore to see if a model based solely on freeze-dried mannitol-sucrose mixtures can be established that will be able to predict water contents for samples containing proteins, excipients or having a lower density of freeze-dried solids. Samples were measured by NIR, standard normal variate (SNV) corrected and the obtained spectra were compared with the results from a conventional Karl-Fischer titration by means of multivariate analysis, namely principal component analysis (PCA) and partial least square regression (PLS). For the overall sample set, a highly linear correlation between the NIR and the Karl-Fischer method with a slope of 1.00, an R(2) value of 0.98 and a root mean square error of cross-validation (RMSECV) of 0.15% were found. In a second step samples solely consisting of mannitol and sucrose mixtures were used to build a calibration set, which resulted in a RMSECV of 0.16%. The prediction of the remaining samples, which included protein or excipient containing samples, as well as lower density samples, resulted in a root mean square error of prediction (RMSEP) of 0.19%. Thus the present study demonstrated, that a general model for the determination of the water content by NIR could be established, within the limits investigated. PMID:20800739

Grohganz, Holger; Gildemyn, Delphine; Skibsted, Erik; Flink, James M; Rantanen, Jukka

2010-08-31

113

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

PubMed

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

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

2011-12-14

114

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.

115

TOPICAL REVIEW: Confinement effects on freezing and melting  

Microsoft Academic Search

A review of experimental work on freezing and melting in confinement is presented. A range of systems, from metal oxide gels to porous glasses to novel nanoporous materials, is discussed. Features such as melting-point depression, hysteresis between freezing and melting, modifications to bulk solid structure and solid-solid transitions are reviewed for substances such as helium, organic fluids, water and metals.

Hugo K. Christenson

2001-01-01

116

Freeze substitution followed by low melting point wax embedding preserves histomorphology and allows protein and mRNA localization techniques.  

PubMed

Fixation and embedding are major steps in tissue preservation for histological analysis. However, conventional fixatives like aldehyde-based solutions usually mask tissular epitopes preventing their immunolocalization. Alternative fixation methods used to avoid this drawback, such as cryopreservation, alcohol- or zinc salts-based fixatives do not efficiently preserve tissue and cell morphology. Likewise, paraffin and resin embedding, commonly used for thin sectioning, frequently damage epitopes due to the clearing agents and high temperatures needed along the embedding procedure. Alternatives like cryosectioning avoid the embedding steps but yield sections of poorer quality and are not suitable for all kinds of samples. To overcome these handicaps, we have developed a method that preserves histoarchitecture as well as tissue antigenic properties. This method, which we have named CryoWax, involves freeze substitution of the samples in isopentane and methanol, followed by embedding in low melting point polyester wax. CryoWax has proven efficient in obtaining thin sections of embryos and adult tissues from different species, including amphioxus, zebrafish, and mouse. CryoWax sections displayed optimal preservation of tissue morphology and were successfully immunostained for fixation- and temperature-sensitive antigens. Furthermore, CryoWax has been tested for in situ hybridization application, obtaining positive results. PMID:20830701

Durán, Iván; Marí-Beffa, Manuel; Santamaría, Jesús A; Becerra, José; Santos-Ruiz, Leonor

2011-05-01

117

Water transport in epididymal and ejaculated rhesus monkey (Macaca mulatta) sperm during freezing.  

PubMed

In the present study, we report the effects of cooling ejaculated and epididymal rhesus monkey (Macacamulatta) sperm with and without the presence of a cryoprotective agent, glycerol. Water transport data during freezing of ejaculated and epididymal sperm cell suspensions were obtained at a cooling rate of 20 degrees C/min in the absence of any cryoprotective agents and in the presence of 0.7 M of glycerol, as well. Using previously published values, the macaque sperm cell was modeled as a cylinder of length 73.83 microm with a radius of 0.40 microm and an osmotically inactive cell volume, V(b), of 0.772 V(o), where V(o) is the isotonic cell volume. This translated to a surface area, SA to initial water volume, WV ratio of approximately 22 microm(-1). By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best-fit membrane permeability parameters (reference membrane permeability to water at 0 degrees C, L(pg) or L(pg)[cpa] and the activation energy, E(Lp) or E(Lp)[cpa]) were found to range from: L(pg) or L(pg)[cpa]=0.0020-0.0029 microm/min-atm; E(Lp) or E(Lp)[cpa])=10.6-18.3 kcal/mole. By incorporating these membrane permeability parameters in a recently developed equation (optimal cooling rate, B(opt)=1009.5 x exp(-0.0546 x E(LP) x L(pg) x (SA/WV); where the units of B(opt) are degrees C/min, E(Lp) or E(Lp)[cpa] are kcal/mole, L(pg) or L(pg)[cpa] are mum/min-atm and SA/WV are mum(-1)), we determined the optimal rates of freezing macaque sperm to be approximately 23 degrees C/min (ejaculated sperm in the absence of CPAs), approximately 29 degrees C/min (ejaculated sperm in the presence of glycerol), approximately 24 degrees C/min (epididymal sperm in the absence of CPAs) and approximately 24 degrees C/min (epididymal sperm in the presence of glycerol). In conclusion, the subzero water transport response and consequently the subzero water transport parameters are not significantly different between the ejaculated and epididymal macaque spermatozoa under corresponding cooling conditions. PMID:18694743

Alapati, Raghava; Goff, Kelly; Kubisch, Hans Michael; Devireddy, Ram V

2008-10-01

118

Thermocouple observations of melting and freezing plateaus for metal-carbon eutectics between the copper and palladium points  

Microsoft Academic Search

Melting and freezing plateaus were observed with type-R thermocouples for the metal-carbon eutectics Pd-C, Ni-C, and Fe-C. For Pd-C, no apparent difference between the melting and freezing temperatures was observed at a heating\\/cooling rate of 3 °C\\/min. For Ni-C, the difference was 0.4 °C, and for Fe-C, 1.6 °C. The freezing temperature for Fe-C showed dependence on cooling rate, and

Y. Yamada; F. Sakuma; A. Ono

2000-01-01

119

Enhanced Aqueous Dissolution of a Poorly Water Soluble Drug by Novel Particle Engineering Technology: Spray-Freezing into Liquid with Atmospheric Freeze-Drying  

Microsoft Academic Search

Purpose. The purpose of this work was to investigate spray-freezing into liquid (SFL) and atmospheric freeze-drying (ATMFD) as industrial processes for producing micronized SFL powders with enhanced aqueous dissolution. Micronized SFL powders dried by ATMFD were compared with vacuum freeze-dried SFL powders.

True L. Rogers; Andrew C. Nelsen; Marazban Sarkari; Timothy J. Young; Keith P. Johnston; Robert O. Williams

2003-01-01

120

Passively Operated Spool Valve for Drain-down Freeze Protection of Thermosyphon Water Heaters. Final Technical Report.  

National Technical Information Service (NTIS)

The work done to extend the existing drain-down valve technology to provide passive drain-down freeze protection for thermosyphon-based solar water heaters is described. The basic design of the existing valve model is that of a spool valve, employing a cy...

1982-01-01

121

Effect of glycerol and cholesterol-loaded cyclodextrin on freezing-induced water loss in bovine spermatozoa  

Microsoft Academic Search

Recent experimental data show that incubating bovine sperm with cholesterol-loaded cyclodextrin (CLC) before cryopreserva- tion increases the percentages of motile and viable cells recovered after freezing and thawing, compared with control sperm. In the present study, we report the effect of incubating bovine sperm with CLC on the subzero water transport response and the membrane permeability parameters (reference membrane permeability

G Li; J Saenz; R A Godke; R V Devireddy

2006-01-01

122

An Investigation of the Cryogenic Freezing of Water in Non-Metallic Pipelines  

NASA Astrophysics Data System (ADS)

Pipe freezing is increasingly used in a range of industries to solve otherwise intractable pipe line maintenance and servicing problems. This paper presents the interim results from an experimental study on deliberate freezing of polymeric pipelines. Previous and contemporary works are reviewed. The object of the current research is to confirm the feasibility of ice plug formation within a polymeric pipe as a method of isolation. Tests have been conducted on a range of polymeric pipes of various sizes. The results reported here all relate to freezing of horizontal pipelines. In each case the process of plug formation was photographed, the frozen plug pressure tested and the pipe inspected for signs of damage resulting from the freeze procedure. The time to freeze was recorded and various temperatures logged. These tests have demonstrated that despite the poor thermal and mechanical properties of the polymers, freezing offers a viable alternative method of isolation in polymeric pipelines.

Martin, C. I.; Richardson, R. N.; Bowen, R. J.

2004-06-01

123

Synergistic impacts of land-use change and soil property variation on non-point source nitrogen pollution in a freeze-thaw area  

NASA Astrophysics Data System (ADS)

Quantifying the non-point source (NPS) nitrogen pollution response to the varied land-use and soil properties in highly agricultural regions is critical for the proper management of NPS pollution. This study simulated the NPS nitrogen loading responses to variations of land-use and soil from 1979 to 2009. The Soil and Water Assessment Tool (SWAT) was used to model the NPS organic nitrogen and nitrate loading in a freeze-thaw area in northeast China. The temporal-spatial simulations of land-use in four periods indicated that the NPS nitrogen loading responded to the disappearance of wetlands and the conversion of uplands to paddy rice. After updating the soil data, the watershed NPS nitrogen loading decreased, and the spatial distribution of the loading indicated that the NPS organic nitrogen was more sensitive than was the nitrate to soil variation. F-tests were employed to assess the significance of each of the predictor variables in five types of scenarios. Overall, the results indicate that the watershed NPS nitrogen loading is sensitive to changes of soil and land-use, but soil changes have a more significant impact. The results of this study also suggest that temperature has significant effects on NPS nitrogen yield and that it caused the twin peaks in the temporal scale. Increasing the temperature above zero in April caused a temporal shift in soil water movement and transported nitrogen pollution earlier in the year, causing an increased loading in water before the summer irrigation, which is advantageous for NPS nitrogen pollution control.

Ouyang, Wei; Huang, Haobo; Hao, Fanghua; Guo, Bobo

2013-07-01

124

Particle characterization of poorly water-soluble drugs using a spray freeze drying technique.  

PubMed

A spray freeze drying (SFD) method was developed to prepare the composite particles of poorly water-soluble drug. The aqueous solution dissolved drug and the functional polymer was sprayed directly into liquid nitrogen. Then, the iced droplets were lyophilized with freeze-dryer to prepare solid particles. Tolbutamide (TBM) and hydroxypropylmethylcellulose (HPMC) were used as a model drug and water-soluble polymeric carrier in this study, respectively. The morphological observation of particles revealed that the spherical particles having porous structure could be obtained by optimizing the loading amount of drug and polymer in the spray solution. Especially, SFD method was characterized that the prepared particles had significantly larger specific surface area comparing with those prepared by the standard spray drying technique. The physicochemical properties of the resultant particles were found to be dependent on the concentration of spray solution. When the solution with high content of drug and polymer was used, the particle size of the resulting composite particles increased and they became spherical. The specific surface area of the particles also increased as a result of higher concentration of solution. The evaluation of spray solution indicated that these results were dependent on the viscosity of spray solution. In addition, when composite particles of TBM were prepared using the SFD method with HPMC as a carrier, the crystallinity of TBM decreased as the proportion of HPMC increased. When the TBM : HPMC ratio reached 1 : 5, the crystallinity of the particles completely disappeared. The dissolution tests showed that the release profiles of poorly water-soluble TBM from SFD composite particles were drastically improved compared to bulk TBM. The 70% release time T(70) of composite particles prepared by the SFD method in a solution of pH 1.2 was quite smaller than that of bulk TBM, while in a solution of pH 6.8, it was slightly lower. In addition, the release rates were faster than those of standard spray dried (SD) composite particles for solutions of pH 1.2 and 6.8, respectively. When composite particles were prepared from mixtures with various composition ratios, T(70) was found to decrease as the proportion of HPMC increased; the release rate was faster than that of bulk TBM in a solution of pH 6.8, as well as solution of pH 1.2. PMID:19571408

Kondo, Masahiro; Niwa, Toshiyuki; Okamoto, Hirokazu; Danjo, Kazumi

2009-07-01

125

Control of crystal growth in water purification by directional freeze crystallization  

NASA Technical Reports Server (NTRS)

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.

Conlon, William M. (Inventor)

1996-01-01

126

Simulating soil freeze/thaw dynamics with an improved pan-Arctic water balance model  

NASA Astrophysics Data System (ADS)

The terrestrial Arctic water cycle is strongly influenced by the presence of permafrost, which is at present degrading as a result of warming. In this study, we describe improvements to the representation of processes in the pan-Arctic Water Balance Model (PWBM) and evaluate simulated soil temperature at four sites in Alaska and active-layer thickness (ALT) across the pan-Arctic drainage basin. Model improvements include new parameterizations for thermal and hydraulic properties of organic soils; an updated snow model, which accounts for seasonal changes in density and thermal conductivity; and a new soil freezing and thawing model, which simulates heat conduction with phase change. When compared against observations across Alaska within differing landscape vegetation conditions in close proximity to one another, PWBM simulations show no systematic soil temperature bias. Simulated temperatures agree well with observations in summer. In winter, results are mixed, with both positive and negative biases noted at times. In two pan-Arctic simulations forced with atmospheric reanalysis, the model captures the mean in observed ALT, although predictability as measured by correlation is limited. The geographic pattern in northern hemisphere permafrost area is well estimated. Simulated permafrost area differs from observed extent by 7 and 17% for the two model runs. Results of two simulations for the periods 1996-1999 and 2066-2069 for a single grid cell in central Alaska illustrate the potential for a drying of soils in the presence of increases in ALT, annual total precipitation, and winter snowfall.

Rawlins, M. A.; Nicolsky, D. J.; McDonald, K. C.; Romanovsky, V. E.

2013-12-01

127

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

ERIC Educational Resources Information Center

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…

McCleary, John M.

128

Modeling of flow and solidification of liquid water during unidirectional freezing in porous media  

NASA Astrophysics Data System (ADS)

Flow and phase change of liquid in porous media are fundamental processes in earth science and soil physics. Particularly in cold region or periglacial environment, the flow and solidification of pore water in the ground simultaneously occur and their collective interactions control the growth of ice lenses and upward displacement of surface called as frost heave. In the nucleation and growth of ice lenses, the homogeneous mixture of soil particles and pore water is transformed to the heterogeneous structure due to the water redistribution and the particle migration. Unfrozen water that is adsorbed to the particle surface or confined to capillary regions plays an important role in the formation of ice lenses and its behaviors have been investigated from a perspective of premelting dynamics (e.g., Worster and Wettlaufer 2006). In the porous media below the nominal melting temperature, intermolecular forces that act between particles and ice through the liquid thin film produce the net thermomolecular force that is responsible for the particle separation form the ice lenses(Dash et al. 2006). Although the mechanisms of ice lens formation have been investigated by many researchers, still large uncertainties remain and more experimental constraints are required. Here we present experimental results of ice lens formation, particularly focusing on the role of grain size and compare the model by Rempel et al (2004). We have performed the unidirectional freezing experiments using water-saturated glass beads that have uniform structures. Since the flow of water in porous media depends on the particles size and pore throat size (Darcy's law), we have prepared various sizes of glass beads from submicron to submillimeter. Our experiments reveal the clear relationships between the host particle sizes and nucleated location and lens thickness. Part of this work is already published in Saruya et al, PRE but we extended to smaller sized regime. We compared our experimental results to the numerical predictions that were modified to our experimental conditions based upon Rempel et al. (2004). The comparison between the experimental results and numerical predictions emphasizes the importance of kinetics due to the flow in liquid thin film and implies the kind of dominant van der Waals interactions that controls the behavior of liquid thin film.

Saruya, Tomotaka; Rempel, Alan; Kurita, Kei

2014-05-01

129

Zero point energy of polyhedral water clusters.  

PubMed

Polyhedral water clusters (PWCs) are cage-like (H2O)n clusters where every O participates in exactly three H bonds. For a database of 83 PWCs, 8 < or = n < or = 20, geometry was optimized and zero point energy (ZPE) was calculated at the B3LYP/6-311++G** level. ZPE correlates negatively with electronic energy (E0): each increase of 1 kcal/mol in E0 corresponds to a decrease of about 0.11 kcal/mol in ZPE. For each n, a set of four connectivity parameters accounts for 98% or more of the variance in ZPE. Linear regression of ZPE against n and this set gives an RMS error of 0.13 kcal/mol. The contributions to ZPE from stretch modes only (ZPE(S)) and from torsional modes only (ZPE(T)) also correlate strongly with E0 and with each other. PMID:16833891

Anick, David J

2005-06-30

130

Thermodynamic effects accompanying freezing of two water layers separated by a sea ice sheet  

NASA Astrophysics Data System (ADS)

Laboratory modeling results of freezing a system of fresh and seawater layers separated by a sea ice sheet are presented and analyzed. They are supplemented by calculations using a thermodynamic model [1] modified for the laboratory conditions.

Bogorodskiy, P. V.; Marchenko, A. V.

2014-03-01

131

Combined impacts of freeze-thaw processes on paddy land and dry land in Northeast China.  

PubMed

The quantity of spring snowmelt infiltration and runoff, which affects the hydrology of the freeze zone, depends on the antecedent soil water content (SWC) conditions at the time of the soil's freezing. An understanding of the characteristics of frozen soil is essential for spring sowing in the agricultural freeze zones. The main goal of this study was to evaluate the differences in the freeze-thaw process and the freeze-thaw-induced water redistribution between the paddy and dry lands in a freeze zone. For this purpose, a field study was conducted in the winter of 2011-2012 for two types of farmlands in Northeast China. To illustrate the soil's frost dynamics over time, the measured SWCs at different depths (15, 30, 60, and 90 cm) were transformed into different expressions including the SWC dynamic, the frozen soil's profile, and the freezing and thawing front trace. The freezing characteristics in the paddy land, in contrast to that in the dry land, had a higher freezing point temperature, a larger amount of water movement to the upper layer, and a 2.76 mm larger accumulation of water in the upper layer. However, the increase of SWC (which is equivalent to thawing) was evidently faster than the decrease of SWC (which is equivalent to freezing). The water in the frozen soil's profile was most likely redistributed towards the freezing front before soil temperature (ST) falls below the freezing point. The findings may partially explain the soil's freeze-thaw characteristics for the different stages as well as the combined impact of these characteristics with farmland use types on soil hydrology; the findings may also provide a foundation for forecasting the hydrologic response of the freeze-thaw process and provide guidance for management strategies dealing with seasonally frozen agricultural soils. PMID:23584030

Chen, Siyang; Ouyang, Wei; Hao, Fanghua; Zhao, Xuchen

2013-07-01

132

Freezing point and solid-liquid interfacial free energy of Stockmayer dipolar fluids: A molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

Stockmayer fluids are a prototype model system for dipolar fluids. We have computed the freezing temperatures of Stockmayer fluids at zero pressure using three different molecular-dynamics simulation methods, namely, the superheating-undercooling method, the constant-pressure and constant-temperature two-phase coexistence method, and the constant-pressure and constant-enthalpy two-phase coexistence method. The best estimate of the freezing temperature (in reduced unit) for the Stockmayer (SM) fluid with the dimensionless dipole moment ?*=1, 2, 3 is 0.656 +/- 0.001, 0.726 +/- 0.002, and 0.835 +/- 0.005, respectively. The freezing temperature increases with the dipolar strength. Moreover, for the first time, the solid-liquid interfacial free energies ? of the fcc (111), (110), and (100) interfaces are computed 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, i.e., ?100 > ?110 > ?111.

Wang, Jun; Apte, Pankaj A.; Morris, James R.; Zeng, Xiao Cheng

2013-09-01

133

Freezing point and solid-liquid interfacial free energy of Stockmayer dipolar fluids: a molecular dynamics simulation study.  

PubMed

Stockmayer fluids are a prototype model system for dipolar fluids. We have computed the freezing temperatures of Stockmayer fluids at zero pressure using three different molecular-dynamics simulation methods, namely, the superheating-undercooling method, the constant-pressure and constant-temperature two-phase coexistence method, and the constant-pressure and constant-enthalpy two-phase coexistence method. The best estimate of the freezing temperature (in reduced unit) for the Stockmayer (SM) fluid with the dimensionless dipole moment ?*=1, ?2, ?3 is 0.656 ± 0.001, 0.726 ± 0.002, and 0.835 ± 0.005, respectively. The freezing temperature increases with the dipolar strength. Moreover, for the first time, the solid-liquid interfacial free energies ? of the fcc (111), (110), and (100) interfaces are computed 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, i.e., ?100 > ?110 > ?111. PMID:24070303

Wang, Jun; Apte, Pankaj A; Morris, James R; Zeng, Xiao Cheng

2013-09-21

134

Subzero water permeability parameters and optimal freezing rates for sperm cells of the southern platyfish, Xiphophorus maculatus.  

PubMed

This study reports the subzero water transport characteristics (and empirically determined optimal rates for freezing) of sperm cells of live-bearing fishes of the genus Xiphophorus, specifically those of the southern platyfish Xiphophorus maculatus. These fishes are valuable models for biomedical research and are commercially raised as ornamental fish for use in aquariums. Water transport during freezing of X. maculatus sperm cell suspensions was obtained using a shape-independent differential scanning calorimeter technique in the presence of extracellular ice at a cooling rate of 20 degrees C/min in three different media: (1) Hanks' balanced salt solution (HBSS) without cryoprotective agents (CPAs); (2) HBSS with 14% (v/v) glycerol, and (3) HBSS with 10% (v/v) dimethyl sulfoxide (DMSO). The sperm cell was modeled as a cylinder with a length of 52.35 microm and a diameter of 0.66 microm with an osmotically inactive cell volume (Vb) of 0.6 V0, where V0 is the isotonic or initial cell volume. This translates to a surface area, SA to initial water volume, WV ratio of 15.15 microm(-1). By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the best fit membrane permeability parameters (reference membrane permeability to water at 0 degrees C, Lpg or Lpg [cpa] and the activation energy, E(Lp) or E(Lp) [cpa]) were found to range from: Lpg or Lpg [cpa] = 0.0053-0.0093 microm/minatm; E(Lp) or E(Lp) [cpa] = 9.79-29.00 kcal/mol. By incorporating these membrane permeability parameters in a recently developed generic optimal cooling rate equation (optimal cooling rate, [Formula: see text] where the units of B(opt) are degrees C/min, E(Lp) or E(Lp) [cpa] are kcal/mol, L(pg) or L(pg) [cpa] are microm/minatm and SA/WV are microm(-1)), we determined the optimal rates of freezing X. maculatus sperm cells to be 28 degrees C/min (in HBSS), 47 degrees C/min (in HBSS+14% glycerol) and 36 degrees C/min (in HBSS+10% DMSO). Preliminary empirical experiments suggest that the optimal rate of freezing X. maculatus sperm in the presence of 14% glycerol to be approximately 25 degrees C/min. Possible reasons for the observed discrepancy between the theoretically predicted and experimentally determined optimal rates of freezing X. maculatus sperm cells are discussed. PMID:15925577

Pinisetty, D; Huang, C; Dong, Q; Tiersch, T R; Devireddy, R V

2005-06-01

135

Freezing curve-based monitoring to quickly evaluate the viability of biological materials subject to freezing or thermal injury.  

PubMed

This paper is aimed at investigating the roles of freezing dynamics of a liquid droplet to characterize the properties of the material. In particular, freezing curve-based monitoring was proposed to quickly evaluate the viability of biological materials subject to freezing, re-warming, or other kinds of injury, which is an extremely important issue in practices such as cryobiology, hyperthermia, or freshness evaluation of bio-samples. An integrated micro analysis device was fabricated which is simple in structure and cheap to make. Preliminary freezing results demonstrated that minor changes in a biological material due to freezing or warming injury might result in a significant deviation of its freezing curve from that of the intact biomaterials. Several potential thermal indexes to quantify the material features were pointed out. Further, experiments were performed on some freezing and thawing processes of small amount of water on a cooling surface to test the effects of droplet sizes, measurement sites, cooling strength, and cooling geometry, etc., on the freezing responses of a water droplet. Their implementation in developing a new micro analysis system were suggested. This freezing curve-based monitoring method may open a new strategy for the evaluation of biomaterials subject to destruction in diverse fields. PMID:12844203

Liu, Jing; Zhou, Yi-Xin

2003-09-01

136

Immersion Freezing of Water and Aqueous Ammonium Sulfate Droplets Initiated by Humic-Like Substances as a Function of Water Activity  

NASA Astrophysics Data System (ADS)

Immersion freezing of water and aqueous (NH4)2SO4 droplets containing leonardite (LEO) and pahokee peat (PP) serving as surrogates for humic-like substances (HULIS) has been investigated. Organic aerosol containing HULIS are ubiquitous in the atmosphere; however, their potential for ice cloud formation is uncertain. Immersion freezing has been studied for temperatures as low as 215 K and solution water activity, aw, from 0.85 to 1.0. The freezing temperatures of water and aqueous solution droplets containing LEO and PP are 5-15 K warmer than homogeneous ice nucleation temperatures. Heterogeneous freezing temperatures can be represented by a horizontal shift of the ice melting curve as a function of solution aw and ?aw by 0.2703 and 0.2466, respectively. Corresponding heterogeneous ice nucleation rate coefficients, Jhet, are (9.6×2.5)x104 and (5.4×1.4)x104 cm-2 s-1 for LEO and PP containing droplets, respectively, and remain constant along freezing curves characterized by ?aw. Consequently predictions of freezing temperatures and kinetics can be made without knowledge of the solute type when relative humidity and ice nuclei (IN) surface areas are known. The acquired ice nucleation data are applied to evaluate different approaches to fit and reproduce experimentally derived frozen fractions. In addition, we apply a basic formulation of classical nucleation theory (?(T)-model) to calculate contact angles and frozen fractions. Contact angles calculated for each ice nucleus as a function of temperature, ?(T)-model, reproduce exactly experimentally derived frozen fractions without involving free-fit parameters. However, assigning the IN a single contact angle for the entire population (single-? model) is not suited to represent the frozen fractions. Application of ?-PDF, active sites, and deterministic model approaches to measured frozen fractions yield similar good representations. Furthermore, when using a single parameterization of ?-PDF or active sites distribution to fit all individual aw immersion freezing data simultaneously, frozen fraction curves are not reproduced. This implies that these fitting formulations cannot be applied to immersion freezing of aqueous solutions, and suggests that derived fit parameters do not represent independent particle properties. Thus, from fitting frozen fractions only, the underlying ice nucleation mechanism and nature of the ice nucleating sites cannot be inferred. In contrast to using fitted functions obtained to represent experimental conditions only, we suggest to use experimentally derived Jhet as a function of temperature and aw that can be applied to conditions outside of those probed in laboratory. This is because Jhet(T) is independent of time and IN surface areas in contrast to the fit parameters obtained by representation of experimentally derived frozen fractions.

Rigg, Y.; Alpert, P. A.; Knopf, D. A.

2013-12-01

137

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

SciTech Connect

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 and gas producing regions of Wyoming, are well suited for application of these processes in combination. Specifically, the objectives of this research are related to the development of a commercially-economic FTE (freeze-thaw/evaporation) process for the treatment and purification of water produced in conjunction with oil and natural gas. The research required for development of this process consists of three tasks: (1) a literature survey and process modeling and economic analysis; (2) laboratory-scale process evaluation; and (3) field demonstration of the process. Results of research conducted for the completion of these three tasks indicate that produced water treatment and disposal costs for commercial application of the process, would be in the range of $0.20 to $0.30/bbl in the Rocky Mountain region. FTE field demonstration results from northwestern New Mexico during the winter of 1995--96 indicate significant and simultaneous removal of salts, metals, and organics from produced water. Despite the unusually warm winter, process yields demonstrate disposal volume reductions on the order of 80% and confirm the potential for economic production of water suitable for various beneficial uses. The total dissolved solids concentrations of the FTE demonstration streams were 11,600 mg/L (feed), 56,900 mg/L (brine), and 940 mg/L (ice melt).

Boysen, J.E.; Walker, K.L.; Mefford, J.L.; Kirsch, J.R. [Resource Technology Corp., Laramie, WY (United States); Harju, J.A. [North Dakota Univ., Grand Forks, ND (United States). Energy and Environmental Research Center

1996-06-01

138

Freezing cold injury.  

PubMed

The pathogenesis of freezing cold injuries (FCI) is not yet entirely understood. Two possible hypothesis emerge: 1) Injury is a direct result of cryogenic insult to the cells. 2) Injury is secondary to vascular stasis which leads to anoxia. In clinical congelatio ice crystallization takes place in the EC-space. When water is transformed into ice, the osmolality in this compartment will increase leading to a passive diffusion of water from the IC-space. Cell dehydration modifies protein structure, alters membrane lipids and cellular pH leading to destructions incompatible with cell survival. Cold induces vasoconstriction of both arterioles and venules, which enhances peripheral filtration and raises plasma viscosity. The stability of red corpuscle aggregates increases and showers of emboli course microvessels. Finally progressive thrombosis will end up in anoxia. The indirect vascular effect has earlier been interpreted similar to that found in non-freezing injuries. Recent studies have, however, shown, that endothelial cells are very sensitive to freezing. The rheologic part of the pathogenesis therefore also seems to depend on a direct injury to cells. The development of FCI does not always depend on ambient temperature and duration of exposure but more to the heat loss subjected to exposed skin. Wind chill, humidity and wetness are all of significance in this matter. From a clinical point of view FCI are best subdivided into superficial and deep injuries. The superficial frostbite is limited to the skin and nearest subcutaneous tissue. A stringing, pinching pain is often the first symptom. The affected area becomes pale or waxy-white and numb.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1811585

Granberg, P O

1991-01-01

139

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

Microsoft Academic Search

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

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

1998-01-01

140

Freezing tolerance and water relations of Opuntia fragilis from Canada and the United States  

Microsoft Academic Search

To investigate the influence of winter climate on freezing tolerance at the population level, minimum January air temperatures in the field and cold acclimation determined in the laboratory were compared for Opuntia fragilis. Populations occurred at 20 locations as far north as 56[degrees]46' N latitude and at elevations up to 3029 m in Canada and the United States, most of

M. E. Loik; P. S. Nobel

1993-01-01

141

Interfacial Electrical Effects Observed during the Freezing of Dilute Electrolytes in Water.  

National Technical Information Service (NTIS)

Dilute solutions of about 50 typical salts, acids, and bases in the concentration range 10 to the -6 to 10 to the -3 were frozen at nonequilibrium rates. The freezing potential, charge separation across the phase boundary, and chemical composition of the ...

A. W. Cobb G. W. Gross

1969-01-01

142

Homogeneous ice nucleation from aqueous inorganic/organic particles representative of biomass burning: water activity, freezing temperatures, nucleation rates.  

PubMed

Homogeneous ice nucleation plays an important role in the formation of cirrus clouds with subsequent effects on the global radiative budget. Here we report on homogeneous ice nucleation temperatures and corresponding nucleation rate coefficients of aqueous droplets serving as surrogates of biomass burning aerosol. Micrometer-sized (NH(4))(2)SO(4)/levoglucosan droplets with mass ratios of 10:1, 1:1, 1:5, and 1:10 and aqueous multicomponent organic droplets with and without (NH(4))(2)SO(4) under typical tropospheric temperatures and relative humidities are investigated experimentally using a droplet conditioning and ice nucleation apparatus coupled to an optical microscope with image analysis. Homogeneous freezing was determined as a function of temperature and water activity, a(w), which was set at droplet preparation conditions. The ice nucleation data indicate that minor addition of (NH(4))(2)SO(4) to the aqueous organic droplets renders the temperature dependency of water activity negligible in contrast to the case of aqueous organic solution droplets. The mean homogeneous ice nucleation rate coefficient derived from 8 different aqueous droplet compositions with average diameters of ?60 ?m for temperatures as low as 195 K and a(w) of 0.82-1 is 2.18 × 10(6) cm(-3) s(-1). The experimentally derived freezing temperatures and homogeneous ice nucleation rate coefficients are in agreement with predictions of the water activity-based homogeneous ice nucleation theory when taking predictive uncertainties into account. However, the presented ice nucleation data indicate that the water activity-based homogeneous ice nucleation theory overpredicts the freezing temperatures by up to 3 K and corresponding ice nucleation rate coefficients by up to ?2 orders of magnitude. A shift of 0.01 in a(w), which is well within the uncertainty of typical field and laboratory relative humidity measurements, brings experimental and predicted freezing temperatures and homogeneous ice nucleation rate coefficients into agreement. The experimentally derived ice nucleation data are applied to constrain the water activity-based homogeneous ice nucleation theory to smaller than ±1 order of magnitude compared to the predictive uncertainty of larger than ±6 orders of magnitude. The atmospheric implications of these findings are discussed. PMID:21235213

Knopf, Daniel A; Rigg, Yannick J

2011-02-10

143

Microautoradiography of Water-Soluble Compounds in Plant Tissue after Freeze-Drying and Pressure Infiltration with Epoxy Resin  

PubMed Central

It is difficult to retain and localize radioactive, water-soluble compounds within plant cells. Existing techniques retain water-soluble compounds with varying rates of efficiency and are limited to processing only a few samples at one time. We developed a modified pressure infiltration technique for the preparation of microautoradiographs of 14C-labeled, water-soluble compounds in plant tissue. Samples from cottonwood (Populus deltoides Bartr. ex Marsh.) labeled with 14C were excised, quick frozen in liquid N2, freeze-dried at ?50°C, and pressure-infiltrated with epoxy resin without intermediate solvents or prolonged incubation times. The technique facilitates the mass processing of samples for microautoradiography, gives good cellular retention of labeled water-soluble compounds, and is highly reproducible. Images Fig. 2

Vogelmann, Thomas C.; Dickson, Richard E.

1982-01-01

144

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

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

145

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

Code of Federal Regulations, 2010 CFR

...2007-07-01 2007-07-01 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...

2007-07-01

146

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

Code of Federal Regulations, 2010 CFR

...2011-07-01 2011-07-01 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...

2011-07-01

147

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

Code of Federal Regulations, 2010 CFR

...2008-07-01 2008-07-01 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...

2008-07-01

148

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

Code of Federal Regulations, 2010 CFR

...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...

2012-07-01

149

Plant cover, soil temperature, freeze, water stress, and evapotranspiration conditions. [south Texas  

NASA Technical Reports Server (NTRS)

Emissive and reflective data for 10 days, and IR data for 6 nights in south Texas scenes were analyzed after procedures were developed for removing cloud-affected data. HCMM radiometric temperatures were: within 2 C of dewpoint temperatures on nights when air temperature approached dewpoint temperatures; significantly correlated with variables important in evapotranspiration; and, related to freeze severity and planting depth soil temperatures. Vegetation greenness indexes calculated from visible and reflective IR bands of NOAA-6 to -9 meteorological satellites will be useful in the AgRISTARS program for seasonal crop development, crop condition, and drought applications.

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

1981-01-01

150

Single-point watering of lead/acid batteries  

NASA Astrophysics Data System (ADS)

Banks of flooded-electrolyte lead/acid batteries of conventional (antimonial) design require periodic additions of water. This is most easily accomplished by means of single-point watering systems. A discussion is given of the many technical problems facing designers of such systems in order to provide a service that is both totally reliable and safe. Other advantages of single-point watering systems are also highlighted.

Sivertsen, Dagfinn B.

151

Evaluation of the freeze-thaw/evaporation process for the treatment of produced waters. Quarterly technical progress report, January 1--March 31, 1994  

SciTech Connect

The use of freeze-crystallization is being increasingly acknowledged as a low-cost, energy-efficient method for purifying contaminated water. Freeze-crystallization has been shown to be effective in removing a wide variety of contaminants from water. Water purification by using natural conditions to promote freezing appears to be an extremely attractive process for the treatment of contaminated water in many areas where natural climatic conditions will seasonally promote freezing. 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 objectives of this research are related to development of a commercially-economic natural freeze-thaw/evaporation (FTE) process for the treatment and purification of water produced in conjunction with oil and gas. During the reporting period of 1/1/94 to 3/31/94, project research concentrated on Subtasks 2.0 (Task 2 Project Reporting) and 2.1 (Laboratory-scale FTE Simulations) . The objectives of Task 2 are to conduct laboratory- and bench-scale simulations for optimizing the design of the FTE process. Task 2 requires completion of six subtasks: Subtask 2.0 - Task 2 Project Reporting (initiated 3/1/93), Subtask 2.1 - Laboratory-scale FTE Simulations, Subtask 2.2 Re-evaluation of Process Economics Based on Laboratory-scale Process Simulation Results, Subtask 2.3 - Bench-scale FTE Simulations, Subtask 2.4 - Economic Assessment of Bench-scale Simulations, and Subtask 2.5 - Technical Report of Task 2. The construction, shakedown, and operation of the laboratory-scale process simulations planned were planned for this quarter (Subtask 2.1).

Boysen, J.; Morotti, J.

1994-04-01

152

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Bottled water, point-of-use, and point-of-entry...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS (CONTINUED) NATIONAL PRIMARY DRINKING WATER REGULATIONS IMPLEMENTATION Exemptions...

2013-07-01

153

Effects of temperatures near the freezing point on N2O emissions, denitrification and on the abundance and structure of nitrifying and denitrifying soil communities.  

PubMed

Climate warming in temperate regions may lead to decreased soil temperatures over winter as a result of reduced snow cover. We examined the effects of temperatures near the freezing point on N(2)O emissions, denitrification, and on the abundance and structure of soil nitrifiers and denitrifiers. Soil microcosms supplemented with NO3 - and/or NO3 - plus red clover residues were incubated for 120 days at -4 °C, -1 °C, +2 °C or +5 °C. Among microcosms amended with residues, N(2)O emission and/or denitrification increased with increasing temperature on Days 2 and 14. Interestingly, N(2)O emission and/or denitrification after Day 14 were the greatest at -1 °C. Substantial N(2) O emissions were only observed on Day 2 at +2 °C and +5 °C, while at -1 °C, N(2)O emissions were consistently detected over the duration of the experiment. Abundances of ammonia oxidizing bacteria (AOB) and archaea (AOA), Nitrospira-like bacteria and nirK denitrifiers were the lowest in soils at -4 °C, while abundances of Nitrobacter-like bacteria and nirS denitrifiers did not vary among temperatures. Community structures of nirK and nirS denitrifiers and Nitrobacter-like bacteria shifted between below-zero and above-zero temperatures. Structure of AOA and AOB communities also changed but not systematically among frozen and unfrozen temperatures. Results indicated shifts in some nitrifier and denitrifier communities with freezing and a surprising stimulation of N(2)O emissions at -1 °C when NO3 - and C are present. PMID:22882277

Wertz, Sophie; Goyer, Claudia; Zebarth, Bernie J; Burton, David L; Tatti, Enrico; Chantigny, Martin H; Filion, Martin

2013-01-01

154

Liquid-Liquid Critical Point in Heavy Water  

Microsoft Academic Search

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

Osamu Mishima

2000-01-01

155

Doping Experiments with Water Triple-Point Cells  

NASA Astrophysics Data System (ADS)

Water triple-point cells were manufactured with the ad hoc addition of known amounts ((1 to 10) ?mol · mol-1) of Si and Na impurities to cell high-purity water. The depressions of the triple-point temperatures realized by the doped cells with respect to 273.16 K were measured and found substantially different from what is expected by Raoult's law for ideal diluted solutions.

Peruzzi, A.; Dobre, M.; Strouse, G.; Van Geel, J.

2011-08-01

156

Passively operated spool valve for drain-down freeze protection of thermosyphon water heaters. Final technical report  

SciTech Connect

The work done to extend the existing drain-down valve technology to provide passive drain-down freeze protection for thermosyphon-based solar water heaters is described. The basic design of the existing valve model is that of a spool valve, employing a cylindrical spool which moves axially in a mating cartridge to open and close o-rings at the two operating extremes (drain and operate) to perform the valving function. Three passive actuators to drive the basic valving mechanism were designed, fabricated, and tested. Two piping configurations used to integrate the spool valve with the thermosyphon system are described, as are the passive actuators. The three actuator designs are: photovoltaic driven, refrigerant-based bellows, and heat motor cable-drive designs. Costs are compared for the alternative actuator designs, and operating characteristics were examined for the thermosyphon system, including field tests. The market for the valve for thermosyphon systems is then assessed. (LEW)

None

1982-04-30

157

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

NASA Technical Reports Server (NTRS)

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.

Cutbirth, J. Michael

2012-01-01

158

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

PubMed

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 24 h), drip loss, and salt-induced water uptake were measured. Reflectance measurements were recorded from 400 to 2,500 nm in both raw and freeze-dried breast meat samples. Raw and freeze-dried samples had similar spectra in the visible region (400-750 nm), but the freeze-dried samples exhibited numerous bands in the NIR region (750-2,500 nm) corresponding to muscle proteins and lipids that were not observed in the NIR spectra of the raw samples. Linear discriminate analyses were used to classify fillets as high-WHC or low-WHC according to predicted meat quality characteristics. Using the visible spectra (400-750 nm), fillets could be correctly classified into high-WHC and low-WHC groups based on drip loss and salt-induced water uptake with 88 to 92% accuracy in raw samples and 79 to 86% accuracy in freeze-dried samples. Using the NIR spectra (750-2,500 nm), fillets could be correctly classified into high-WHC and low-WHC groups with 74 to 76% accuracy in raw samples and 85 to 86% accuracy in freeze-dried samples. Thus, freeze-drying enhanced the accuracy of WHC classification using the NIR portion of the spectra. Data from this study demonstrate the potential for utilizing vis/NIR spectroscopy as a method for classifying broiler breast meat according to WHC. PMID:24864280

Bowker, B; Hawkins, S; Zhuang, H

2014-07-01

159

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

NASA Technical Reports Server (NTRS)

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.

Albright, A. E.

1984-01-01

160

Effect of sucrose on the freeze–thaw stability of rice starch gels: Correlation with microstructure and freezable water  

Microsoft Academic Search

Rice starch gels subjected to repeated freezing and thawing tend to decrease in quality. This study investigated how the addition of sucrose to rice starch gels affects factors commonly used to measure quality. Rice starch gels containing 0–20% sucrose were treated to 5 freeze–thaw cycles. The result showed that sucrose effectively reduced the % syneresis. Scanning electron micrographs of freeze–thaw

Thunyaboon Arunyanart; Sanguansri Charoenrein

2008-01-01

161

Modelling Water Flow, Heat Transport, Soil Freezing and Thawing, and Snow Processes in a Clayey, Subsurface Drained Agricultural Field  

NASA Astrophysics Data System (ADS)

Simulation of hydrological processes for the purposes of agricultural water management and protection in boreal environment requires description of winter time processes, including heat transport, soil freezing and thawing, and snow accumulation and melt. Finland is located north of the latitude of 60 degrees and has one third to one fourth of the total agricultural land area (2.3 milj. ha) on clay soils (> 30% of clay). Most of the clayey fields are subsurface drained to provide efficient drainage and to enable heavy machines to operate on the fields as soon as possible after the spring snowmelt. Generation of drainflow and surface runoff in cultivated fields leads to nutrient and sediment load, which forms the major share of the total load reaching surface waters at the national level. Water, suspended sediment, and soluble nutrients on clayey field surface are conveyed through the soil profile to the subsurface drains via macropore pathways as the clayey soil matrix is almost impermeable. The objective of the study was to develop the missing winter related processes into the FLUSH model, including soil heat transport, snow pack simulation and the effects of soil freezing and thawing on the soil hydraulic conductivity. FLUSH is an open source (MIT license), distributed, process-based model designed to simulate surface runoff and drainflow in clayey, subsurface drained agricultural fields. 2-D overland flow is described with the diffuse wave approximation of the Saint Venant equations and 3-D subsurface flow with a dual-permeability model. Both macropores and soil matrix are simulated with the Richards equation. Soil heat transport is described with a modified 3-D convection-diffusion equation. Runoff and groundwater data was available from different periods from January 1994 to April 1999 measured in a clayey, subsurface drained field section (3.6 ha) in southern Finland. Soil temperature data was collected in two locations (to a depth of 0.8 m) next to the experimental field section while snow and frost depths were recorded within the experimental field section. The model was calibrated with 1994 data and validated with soil temperature and snow and frost depth data from the years 1995-1999. The main advantage of the new model was the 3-D distributed nature of the system which made it possible to simulate lateral water and heat fluxes in soil and overland flow on the field surface. Also, the possibility to simulate hydrological conditions in the experimental field continuously from 1994 to 1998 was essential because the main sediment loads in Nordic fields usually occur after snow melt and during autumn rains and the resulting runoff depends on the antecedent moisture conditions in the field. The simulation results revealed differences in soil temperatures within the field area due to the topography of the undulating field. The low lying areas were colder (up to 1 °C) during winter and also remained colder longer in the spring due to the higher water content compared to the drier, upper parts of the slopes. Repeated freezing and thawing cycles during the winter and early spring caused an ice layer to form on the soil surface which promoted generation of surface runoff. The snow cover over the field and the organic matter in the tillage layer had an insulating effect on the soil temperatures.

Warsta, L.; Turunen, M.; Koivusalo, H. J.; Paasonen-Kivekäs, M.; Karvonen, T.; Taskinen, A.

2012-12-01

162

Denaturation of ~nzyme Protein by Freeze-Thawing and Freeze-Drying  

Microsoft Academic Search

The effects of freeze-thawing and freeze-drying on catalase, one of globular proteins, were examined for the purpose of investigating relations of the confor­ mation of protein to its stability against freeze-thawing and freeze-drying. Also the water content of the freeze-dried egg albumin, a representative protein, was measured with or without some additives, for the clarification of the mechanism of their

Naofumi HANAFUSA

163

Towards a robust water content determination of freeze-dried samples by near-infrared spectroscopy  

Microsoft Academic Search

The possibility for determination of the water content in pharmaceutical samples by near-infrared (NIR) spectroscopy has been more widely investigated in the past few years. However, many studies claim that changes in sample composition will require the establishment of a new method. The aim of this study was several fold: firstly to investigate validation aspects of water content determination in

Holger Grohganz; Delphine Gildemyn; Erik Skibsted; James M. Flink; Jukka Rantanen

2010-01-01

164

Studies on the Behavior of Water Triple-Point Cells  

NASA Astrophysics Data System (ADS)

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 different cells were compared with each other and also with the expected value of -7.3×10-4 K.m-1. The effect of the depth of immersion of the TPW cell in the maintenance bath on the water triple-point was studied and discussed here.

Tsai, Shu-Fei

2003-09-01

165

NMR studies of non-freezing water in randomly packed beds of porous particles  

NASA Astrophysics Data System (ADS)

NMR water proton transverse relaxation time distributions are shown to provide valuable information about the distribution of ice and nonfreezing water in complex heterogeneous systems. In a model system consisting of randomly packed Sephadex beads the NMR data confirm that ice inside the porous Sephadex beads coexists as a two phase system with unfrozen dextran gel. The NMR relaxation technique is shown to provide complementary information to both differential scanning calorimetry and cryomicroscopy.

Hills, B. P.; Le Floc'h, G.

166

Isotopic Composition of Water Used in Triple-Point Cells  

NASA Astrophysics Data System (ADS)

Isotopic analysis of the water used in KRISS triple point of water (TPW) cells was performed by three separate laboratories. The ?D and ? 18O isotopic composition of six ampoules, made from two TPW cells, were analyzed by isotope ratio mass spectrometers. The analysis data showed that ?D and ? 18O were - 62.17‰ and - 9.41‰ for the KRISS-2002-Jan cell, and - 36.42‰ and - 4.08‰ for the KRISS-2005-Jun cell. The temperature deviation of the triple point of water for these cells calculated from Kiyosawa’s data and the definition of the TPW were + 45.07?K for the KRISS-2002-Jan cell, and + 25.49?K for the KRISS-2005-Jun cell. The KRISS TPW temperature was + 92?K higher than the CCT-K7 KCRV after correcting for the deviation of the isotopic composition from Vienna Standard Mean Ocean Water.

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

2008-06-01

167

Freezing and melting behavior of an octyl ?-D-glucoside-water binary system--inhibitory effect of octyl ?-D-glucoside on ice crystal formation.  

PubMed

Phase transition behavior of lyotropic liquid crystals of an octyl ?-D-glucoside (OG)-water binary system during ice freezing and melting was studied by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Not the thermotropic, but the lyotropic phase transition due to the change of OG concentration during ice freezing and melting was observed. The concentration-temperature phase diagram of the binary system was constructed. Melting temperature of ice, T(m), lyotropic phase transition temperature, T(tr), and glass transition temperatures of unfrozen phases in the absence and presence of ice, T(g) and T(g)', were shown in the phase diagram. The phase diagram indicated that the OG aqueous system was concentrated to ca. 90-92 wt% by ice freezing and exhibited glass transition at T(g)'. An observation of the concentration-gradient specimen by the cryo-POM showed the evidence of the inhibitory effects of OG on nucleation and growth of ice crystals in the extremely high OG concentration system in which the lamellar liquid crystalline phase was formed. This study provided the importance of the influence of concentration change by ice freezing on the behaviour of the sugar-based surfactant-water system under low temperature conditions. PMID:23133837

Ogawa, Shigesaburo; Asakura, Kouichi; Osanai, Shuichi

2012-12-21

168

Freezing and Food Safety  

MedlinePLUS

... JSR 286) Actions ${title} Loading... Freezing and Food Safety What Can You Freeze? Is Frozen Food Safe? Does Freezing Destroy Bacteria & Parasites? Freshness & Quality Nutrient Retention Enzymes Packaging Freezer Burn Color Changes Freeze Rapidly Freezer - Refrigerator Temperatures Freezer Storage ...

169

BIPM Project: Intercomparison of Water Triple-Point Cells.  

National Technical Information Service (NTIS)

The paper presents the results of an intercomparison between 3 triple point of water cells circulated by the Bureau International des Poids et Measures (BIPM), and a cell which is one of those used as a reference cell at the National Physical Laboratory (...

M. V. Chattle J. Butler

1994-01-01

170

Comparison of Water Triple Point Cells in Finland  

NASA Astrophysics Data System (ADS)

Triple point of water cells from the accredited laboratories in Finland were compared to a batch of cells at the Finnish NMI. The measurements began in 1990 and the last measurements are from 2002. Some cells produced very low temperatures and seemed to change as a function of time.

Weckström, Thua; Uusipaikka, Leena

2003-09-01

171

Latent cold heat energy storage characteristics by means of direct-contact-freezing between oil droplets and cold water solution  

Microsoft Academic Search

Flow and solidification characteristics of paraffin oil droplets (tetradecane with the melting point of 5.8°C, the latent heat of fusion of 229.1 kJ\\/kg and the density of 770 kg\\/m3 at 6°C) ascending in a cold water solution are experimentally investigated. The tetradecane oil is injected from a cylindrical single hole nozzle into the cold water solution and it disperses and

Hideo Inaba; Kenji Sato

1997-01-01

172

Recent Advances in Point-of-Access Water Quality Monitoring  

NASA Astrophysics Data System (ADS)

Clean water is one of our most valuable natural resources. In addition to providing safe drinking water it assures functional ecosystems that support fisheries and recreation. Human population growth and its associated increased demands on water pose risks to maintaining acceptable water quality. It is vital to assess source waters and the aquatic systems that receive inputs from industrial waste and sewage treatment plants, storm water systems, and runoff from urban and agricultural lands. Rapid and confident assessments of aquatic resources form the basis for sound environmental management. Current methods engaged in tracing the presence of various bacteria in water employ bulky laboratory equipment and are time consuming. Thus, real-time water quality monitoring is essential for National and International Health and Safety. Environmental water monitoring includes measurements of physical characteristics (e.g. pH, temperature, conductivity), chemical parameters (e.g. oxygen, alkalinity, nitrogen and phosphorus compounds), and abundance of certain biological taxa. Monitoring could also include assays of biological activity such as alkaline phosphatase, tests for toxins such as microcystins and direct measurements of pollutants such as heavy metals or hydrocarbons. Real time detection can significantly reduce the level of damage and also the cost to remedy the problem. This paper presents overview of state-of-the-art methods and devices used for point-of-access water quality monitoring and suggest further developments in this area.

Korostynska, O.; Arshak, K.; Velusamy, V.; Arshak, A.; Vaseashta, Ashok

173

Point based hydrodynamics applied to shallow water equations  

SciTech Connect

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.

Eltgroth, P.

1994-05-01

174

[Methods of vapour-phase extraction and extractive freezing for the analysis of organic substances dissolved in mineral waters of the Sochi spa area].  

PubMed

The chromatomass-spectrometry method was for the first time employed to study organic substances isolated by vapour-phase extraction from the Matseta sulfide-containing mineral water near Sochi. These substances are found to contain sulphur in different valent forms. A new technique has been developed for the detection of monobasic C2-C6 carboxylic acids in natural mineral water based on the combination of sequential vapour extraction and extractive freezing of the analytes. The proposed method is readily reproducible and has a detection limit of 0.03 mg/l for the analysis of carboxylic acids in water. PMID:19639697

Bekhterev, V N; Kabina, E A; Chekhova, T M; Ostapishin, V D

2009-01-01

175

Dilution of impurities in water triple point cells  

NASA Astrophysics Data System (ADS)

Controlled amounts of Si and Na impurities (0.1 to 0.5 ?mol.mol-1 of Si and 0.2 to 1 ?mol.mol-1 of Na) were diluted in the high-purity water of triple point of water (TPW) cells before sealing the cells. Water samples drawn from the manufactured doped cells were analyzed with high-resolution Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). The TPW temperature of one of the doped cells (the cell that showed a good agreement between the nominal Si and Na amounts and the Si and Na amounts measured by ICP-MS) was measured for different water/ice relative contents. The observed TPW depression was compared to 1) the TPW depression expected from the nominal doping and 2) the TPW depression expected from the total impurity content measured by ICP-MS.

Peruzzi, A.; Dobre, M.; Strouse, G. F.; van Geel, J.; Davis, C.

2013-09-01

176

Peculiar thermodynamics of the second critical point in supercooled water.  

PubMed

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

Bertrand, C E; Anisimov, M A

2011-12-01

177

Water Electrolyzers and the Zero-Point Energy  

NASA Astrophysics Data System (ADS)

The gas emitted from popular water electrolyzer projects manifests unusual energetic anomalies, which include vaporizing tungsten when used in a welding torch and running internal combustion engines on small quantities of the gas. Some claim to run generators in closed loop fashion solely on the gas from the electrolyzer, which is powered solely from the generator. Most investigators believe the energy is from burning hydrogen. A hypothesis is proposed that the dominant energy is not coming from hydrogen, but rather it is coming from charged water gas clusters, which activate and coherently trap zero-point energy.

King, M. B.

178

Freeze-drying fungi using a shelf freeze-drier.  

PubMed

Lyophilization, the removal of water by freezing and then volatilization at low pressure and temperature, has been employed as a standard long-term preservation method for many filamentous fungi. The method outlined involves the use of standard shelf freeze-drying and skimmed milk as a suspending solution/lyoprotectant. This approach has been employed to freeze-dry the majority of the 50,000 fungal strains that have been successfully lyophilized at the Centraal bureau voor Schimmelcultures (CBS) culture collection (http://www.cbs.knaw.nl/). PMID:18080466

Tan, C Shu-hui; van Ingen, Cor W; Stalpers, Joost A

2007-01-01

179

Bayesian Change Point Analysis for Water Pressure Data  

NASA Astrophysics Data System (ADS)

We use wavelets in a Bayesian context to identify changes in the pattern of data collected over time, when missing observations are present. Our work is motivated by the interest in identifying and modeling change points in the measurements of sub-glacial water pressure during melt season along the length of the Bench glacier in Alaska. This modeling will provide insights into the sub-glacial hydrology including the discharge mechanism during the melt season. A Bayesian analysis based on the empirical wavelet coefficients is used to find the change point (Oden and Lynch,1998) in 18 water pressure data sets available.We compare this method with wavelet based method suggested byWang (1995), which examines the empirical wavelet coefficients of the data at the fine scale levels. The above methods have to be adapted for accommodating missing observations, which are present in our data sets.

Chatterjee, A.; Huzurbazar, S. V.; Humphrey, N. F.; Tschetter, T. J.

2007-12-01

180

The Richards Function Applied to Data from Freezing Tests of Growing Shoots  

Microsoft Academic Search

~~~~ Frost resistance of growing Salix viminalis 1. shoots was deter- mined by rating mortality percentage under two commonly used freezing conditions: a condition in which plants were encased in crushed ice and another in which plants were moistened with tap water prior to freezing. The mortality-temperature data were fitted with a logistic function (having a fixed inflection point halfway

Heinrich A. von Fircks; Theo Verwijst

181

Freezing induces a loss of freeze tolerance in an overwintering insect.  

PubMed Central

Cold-hardy insects overwinter by one of two main strategies: freeze tolerance and freeze avoidance by supercooling. As a general model, many freeze-tolerant species overwinter in extreme climates, freeze above -10 degrees C via induction by ice-nucleating agents, and once frozen, can survive at temperatures of up to 40 degrees C or more below the initial freezing temperature or supercooling point (SCP). It has been assumed that the SCP of freeze-tolerant insects is unaffected by the freezing process and that the freeze-tolerant state is therefore retained in winter though successive freeze-thaw cycles of the body tissues and fluids. Studies on the freeze-tolerant larva of the hoverfly Syrphus ribesii reveal this assumption to be untrue. When a sample with a mean 'first freeze' SCP of -7.6 degrees C (range of -5 degrees C to -9.5 degrees C) were cooled, either to -10 degrees C or to their individual SCP, on five occasions, the mean SCP was significantly depressed, with some larvae subsequently freezing as low as -28 degrees C. Only larvae that froze at the same consistently high temperature above -10 degrees C were alive after being frozen five times. The wider occurrence of this phenomenon would require a fundamental reassessment of the dynamics and distinctions of the freeze-tolerant and freeze-avoiding strategies of insect overwintering.

Brown, C. L.; Bale, J. S.; Walters, K. F. A.

2004-01-01

182

Involvement of protein synthesis in the reconsolidation of memory at different time points after formation of conditioned reflex freezing in mice.  

PubMed

The aim of the present work was to study the involvement of protein synthesis in the reconsolidation of memory at different periods of time after training. In mice trained in a conditioned reflex freezing model, memory was reactivated by a reminder combined with administration of the protein synthesis inhibitor cycloheximide. The results showed that suppression of protein synthesis on reactivation of memory 3, 6, and 24 h and 14 and 30 days after training impaired acquired conditioned reflex freezing. These data provide evidence that memories retrieved by a reminder require protein-dependent reorganization at both short (3-6 h) and long (14-30 days) periods after training. PMID:17457537

Murav'eva, E V; Anokhin, K V

2007-05-01

183

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

PubMed

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

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

2007-01-01

184

Isotopic Correction of Water-Triple-Point Cells at NMIJ  

NASA Astrophysics Data System (ADS)

The twenty-one participating laboratories in the international key comparison of water-triple-point cells (CCT-K7) can be classified into three groups: two laboratories that corrected the effect of the isotopic composition of water, four laboratories that had information on the isotopic composition but did not correct the effect, and the remaining laboratories that had no information. There were significant differences in the realized national standard for the triple point of water (TPW) between those laboratories that applied the isotopic correction and those that did not. The isotopic correction is now considered essential for the triple point of water. Since the National Metrology Institute of Japan (NMIJ) did not apply the isotopic correction and estimated large uncertainties at the time of the CCT-K7 comparison, we subsequently developed new cells for the TPW to improve the reliability and to reduce the uncertainty of the realization as a national reference. The isotopic compositions of seven cells were analyzed, and a chemical impurity analysis of one cell was performed. The good consistency among seven cells was shown in the results obtained when the isotopic correction was applied to the realized temperatures measured experimentally. The expanded uncertainty of the new national reference of NMIJ is estimated to be 49 ?K ( k = 2), and as a result of this improvement, the expanded uncertainty for calibrating a water-triple-point cell is 80 ?K. The previous reference of NMIJ, reported in CCT-K7 to have an expanded uncertainty of 302 ?K, is 42 ?K lower than the new one. The new reference value is within the uncertainty of the previous national reference, and the new uncertainty is completely covered by the previous uncertainty. Furthermore, the new reference of NMIJ shows good agreement with the national references of the six laboratories able to apply isotopic corrects to their results for CCT-K7. These facts confirm the validity and the linkage to the CCT-K7 of both the previous and the new national references of NMIJ.

Tamba, Jun; Sakai, Muneo; Kishimoto, Isao; Arai, Masaru

2008-10-01

185

Freeze Technology for Nuclear Applications - 13590  

SciTech Connect

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)

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

186

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.

2008-09-22

187

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...

188

History of water on Mars: a biological perspective.  

NASA Astrophysics Data System (ADS)

The authors have developed a general scenario for the history of liquid water on the surface of Mars and the distribution of water, they have defined epochs in terms of fundamental temperature and pressure values, i.e., the freezing temperature of water and the triple point pressure of water. It is assumed that Mars began with mean temperatures above freezing and atmospheric pressures well above the triple point pressure of water and then evolved to its present state in which the temperature is below the freezing point and the total pressure is approximately equal to the triple point pressure.

McKay, C. P.; Friedman, E. I.; Wharton, R. A.; Davies, W. L.

189

Particle Sorting by Repeated Freezing and Thawing  

Microsoft Academic Search

If a hetrogeneous mixture of particles of various sizes is frozen and thawed repeatedly, the particles are sorted into relatively uniform groups by size. The movement of particles depends on the amount of water between the ice-water interface and the particle, the rate of freezing, the distribution of the particles by size, and the orientation of the freeze-thaw plane.

Arturo E. Corte

1963-01-01

190

Recovery of White Blood Cells After Freezing.  

National Technical Information Service (NTIS)

Whereas the red cells recover from the actual congelation of all the water freezable at -3C, the neutrophils are already injured when only a fraction of the water freezable at -1.5C is congealed. Electron microscope studies of freeze-dried or freeze-subsi...

B. J. Luyet L. J. Menz G. L. Rapatz D. Rasmussen

1971-01-01

191

Involvement of protein synthesis in the reconsolidation of memory at different time points after formation of conditioned reflex freezing in mice  

Microsoft Academic Search

The aim of the present work was to study the involvement of protein synthesis in the reconsolidation of memory at different\\u000a periods of time after training. In mice trained in a conditioned reflex freezing model, memory was reactivated by a reminder\\u000a combined with administration of the protein synthesis inhibitor cycloheximide. The results showed that suppression of protein\\u000a synthesis on reactivation

E. V. Murav’eva; K. V. Anokhin

2007-01-01

192

Preservation of flavor in freeze dried green beans  

NASA Technical Reports Server (NTRS)

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.

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

1973-01-01

193

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

194

GEOtop 2.0: simulating the combined energy and water balance at and below the land surface accounting for soil freezing, snow cover and terrain effects  

NASA Astrophysics Data System (ADS)

GEOtop is a small-scale grid-based simulator that represents the heat and water budgets at and below the soil surface. It represents the energy exchange with the atmosphere, considering the radiative and turbulent fluxes, and describes the three-dimensional subsurface water flow. Furthermore, it reproduces the highly non-linear interaction of the water and energy balance during soil freezing and thawing, and describes the temporal evolution of water and energy budgets in the snow cover and their effect on soil temperature. Here, we describe the core components of GEOtop 2.0 and demonstrate its functioning. Based on a synthetic simulation, we show that the interaction of processes represented in GEOtop 2.0 can result in phenomena that are significant and relevant for applications involving permafrost and seasonally-frozen soils, both in high altitude and latitude regions.

Endrizzi, S.; Gruber, S.; Dall'Amico, M.; Rigon, R.

2013-12-01

195

Freeze prediction model  

NASA Technical Reports Server (NTRS)

Measurements of wind speed, net irradiation, and of air, soil, and dew point temperatures in an orchard at the Rock Springs Agricultural Research Center, as well as topographical and climatological data and a description of the major apple growing regions of Pennsylvania were supplied to the University of Florida for use in running the P-model, freeze prediction program. Results show that the P-model appears to have considerable applicability to conditions in Pennsylvania. Even though modifications may have to be made for use in the fruit growing regions, there are advantages for fruit growers with the model in its present form.

Morrow, C. T. (principal investigator)

1981-01-01

196

Stability against freezing of aqueous solutions on early Mars.  

PubMed

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

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

2009-05-21

197

Modification of physical properties of freeze-dried rice  

NASA Technical Reports Server (NTRS)

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.

Huber, C. S.

1971-01-01

198

BIPM project: Intercomparison of water triple-point cells  

NASA Astrophysics Data System (ADS)

The paper presents the results of an intercomparison between 3 triple point of water cells circulated by the Bureau International des Poids et Measures (BIPM), and a cell which is one of those used as a reference cell at the National Physical Laboratory (NPL). All 4 cells were prepared, stored and measured in the manner normally adopted at NPL. The results of the intercomparison show that over the course of about 6 weeks the temperatures of the 3 circulated cells generally agreed within 0.20 mK, with a maximum difference of 0.27(7) mK. Over the same period, the total variations of temperature measured in the 3 individual cells were 0.04 mK, 0.08 mK and 0.18 mK, respectively; the NPL cell varied by 0.10 mK. Gallium point measurements made over a similar period confirmed that these differences were partly due to small drifts in the thermometer resistance or in the measuring system.

Chattle, M. V.; Butler, J.

1994-12-01

199

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

200

Fundamentals of freeze-drying.  

PubMed

Given the increasing importance of reducing development time for new pharmaceutical products, formulation and process development scientists must continually look for ways to "work smarter, not harder." Within the product development arena, this means reducing the amount of trial and error empiricism in arriving at a formulation and identification of processing conditions which will result in a quality final dosage form. Characterization of the freezing behavior of the intended formulation is necessary for developing processing conditions which will result in the shortest drying time while maintaining all critical quality attributes of the freeze-dried product. Analysis of frozen systems was discussed in detail, particularly with respect to the glass transition as the physical event underlying collapse during freeze-drying, eutectic mixture formation, and crystallization events upon warming of frozen systems. Experiments to determine how freezing and freeze-drying behavior is affected by changes in the composition of the formulation are often useful in establishing the "robustness" of a formulation. It is not uncommon for seemingly subtle changes in composition of the formulation, such as a change in formulation pH, buffer salt, drug concentration, or an additional excipient, to result in striking differences in freezing and freeze-drying behavior. With regard to selecting a formulation, it is wise to keep the formulation as simple as possible. If a buffer is needed, a minimum concentration should be used. The same principle applies to added salts: If used at all, the concentration should be kept to a minimum. For many proteins a combination of an amorphous excipient, such as a disaccharide, and a crystallizing excipient, such as glycine, will result in a suitable combination of chemical stability and physical stability of the freeze-dried solid. Concepts of heat and mass transfer are valuable in rational design of processing conditions. Heat transfer by conduction--the dominant mechanism of heat transfer in freeze-drying--is inefficient at the pressures used in freeze-drying. Steps should be taken to improve the thermal contact between the product and the shelf of the freeze dryer, such as eliminating metal trays from the drying process. Quantitation of the heat transfer coefficient for the geometry used is a useful way of assessing the impact of changes in the system such as elimination of product trays and changes in the vial. Because heat transfer by conduction through the vapor increases with increasing pressure, the commonly held point of view that "the lower the pressure, the better" is not true with respect to process efficiency. The optimum pressure for a given product is a function of the temperature at which freeze-drying is carried out, and lower pressures are needed at low product temperatures. The controlling resistance to mass transfer is almost always the resistance of the partially dried solids above the submination interface. This resistance can be minimized by avoiding fill volumes of more than about half the volume of the container. The development scientist should also recognize that very high concentrations of solute may not be appropriate for optimum freeze-drying, particularly if the resistance of the dried product layer increases sharply with concentration. Although the last 10 years has seen the publication of a significant body of literature of great value in allowing development scientists and engineers to "work smarter," there is still much work needed in both the science and the technology of freeze-drying. Scientific development is needed for improving analytical methodology for characterization of frozen systems and freeze-dried solids. A better understanding of the relationship between molecular mobility and reactivity is needed to allow accurate prediction of product stability at the intended storage temperature based on accelerated stability at higher temperatures. This requires that the temperature dependence of glass transition-associated mobili

Nail, Steven L; Jiang, Shan; Chongprasert, Suchart; Knopp, Shawn A

2002-01-01

201

Colloid-facilitated mobilization of metals by freeze-thaw cycles.  

PubMed

The potential of freeze-thaw cycles to release colloids and colloid-associated contaminants into water is unknown. We examined the effect of freeze-thaw cycles on the mobilization of cesium and strontium in association with colloids in intact cores of a fractured soil, where preferential flow paths are prevalent. Two intact cores were contaminated with cesium and strontium. To mobilize colloids and metal cations sequestered in the soil cores, each core was subjected to 10 intermittent wetting events separated by 66 h pauses. During the first five pauses, the cores were dried at room temperature, and during last five pauses, the cores were subjected to 42 h of freezing followed by 24 h of thawing. In comparison to drying, freeze-thaw cycles created additional preferential flow paths through which colloids, cesium, and strontium were mobilized. The wetting events following freeze-thaw intervals mobilized about twice as many colloids as wetting events following drying at room temperature. Successive wetting events following 66 h of drying mobilized similar amounts of colloids; in contrast, successive wetting events after 66 h of freeze-thaw intervals mobilized greater amounts of colloids than the previous one. Drying and freeze-thaw treatments, respectively, increased and decreased the dissolved cesium and strontium, but both treatments increased the colloidal cesium and strontium. Overall, the freeze-thaw cycles increased the mobilization of metal contaminants primarily in association with colloids through preferential flow paths. These findings suggest that the mobilization of colloid and colloid-associated contaminants could increase when temperature variations occur around the freezing point of water. Thus, climate extremes have the potential to mobilize contaminants that have been sequestered in the vadose zone for decades. PMID:24377325

Mohanty, Sanjay K; Saiers, James E; Ryan, Joseph N

2014-01-21

202

Aqueous-phase photoproduction of hydrogen peroxide in authentic cloud waters: Wavelength dependence, and the effects of filtration and freeze-thaw cycles  

NASA Astrophysics Data System (ADS)

Quantum yields ( ??) of hydrogen peroxide (HOOH) photoproduction are reported at 313, 334, and 366 nm for authentic cloud waters collected over a three-year period (1991-1993) at Whiteface Mountain, New York. Quantum yields of HOOH production (based on the total sample absorbance) in these cloud waters ranged up to 0.014. For each sample the HOOH quantum yield decreased with increasing wavelength: ?313 > ?334 > ?366. Action spectra for HOOH photoproduction in these cloud waters indicate that light between 290 and 380 nm is primarily responsible for the aqueous-phase HOOH photoproduction in tropospheric water drops. Quantum yields at 334 and 366 nm were each highly correlated with quantum yields at 313 nm. The cloud water absorbances per centimeter at 334 and 313 nm were also highly correlated. This suggests that similar classes; of chromophores were responsible for the aqueous-phase HOOH photoformation in the cloud waters from different events over a three-year period. The chromophores have not been identified, thus absolute quantum yields for HOOH formation from specific chromophores in an authentic sample could not be calculated. Comparisons of wavelength-dependent relative quantum yields in a given authentic cloud water sample (assuming Fe(oxalate) 2- was the primary source of HOOH) with those for Fe(oxalate) 2- in well-defined aqueous systems indicate that photolysis of Fe(oxalate) 2- was not the primary source of HOOH photoproduction in any of the nine authentic cloud water samples studied. Filtration (0.5 ?m Teflon) caused only small differences (?15% increase) in rates of HOOH photoformation versus unfiltered controls. Filtration through a 0.05 ?m polycarbonate membrane filter did not cause distinguishable differences in the ultraviolet-visible absorption spectra of a cloud water sample previously filtered with a 0.5 ?m Teflon filter. These observations suggest that particles were neither the dominant source nor the dominant sink of the photoproduced HOOH. Freezing (up to 403 d) caused only minor changes in HOOH photoproduction rates (-9 to + 12%), and in the ultraviolet-visible absorbance spectra and pH values of the cloud water studied. These observations indicate that freeze-thaw cycles in clouds will have only minor influences on the aqueous-phase photoformation of HOOH.

Arakaki, Takemitsu; Anastasio, Cort; Shu, Pauline G.; Faust, Bruce C.

203

Freezing Tolerance in Mytilus Edulis.  

National Technical Information Service (NTIS)

Mytilus edulis tolerates freezing to a tissue temperature of -10 deg C, while Venus mercenaria tolerates only -6 deg C. In both species, tissues are injured when 64 per cent of cellular water has been moved to form ice. In Mytilus, 20 percent of cell wate...

R. J. Williams

1969-01-01

204

Energies of freezing and frost desiccation.  

PubMed

A stable cellulose paper system was studied to relate water distribution data, as obtained previously from plant tissues, to the analysis of freezing energy. Water distribution data for the cellulose system were obtained by several techniques and were coordinated with calorimetric data. The effect of the cellulose system on the latent heat of freezing was evaluated to estimate activation energies as functions of the amount of associated liquid water. Similar activation energies of water phase transitions in critical plant tissue systems may be heritable characteristics that affect freezing stress. Adhesion energy, that develops between ice and hydrophilic polymer systems as they compete for liquid water in a complex interface, was suggested as one possible source of freezing stress. This does not occur in frost desiccation. PMID:16658785

Olien, C R

1974-05-01

205

Drought increases freezing tolerance of both leaves and xylem of Larrea tridentata.  

PubMed

Drought and freezing are both known to limit desert plant distributions, but the interaction of these stressors is poorly understood. Drought may increase freezing tolerance in leaves while decreasing it in the xylem, potentially creating a mismatch between water supply and demand. To test this hypothesis, we subjected Larrea tridentata juveniles grown in a greenhouse under well-watered or drought conditions to minimum temperatures ranging from -8 to -24 °C. We measured survival, leaf retention, gas exchange, cell death, freezing point depression and leaf-specific xylem hydraulic conductance (k?). Drought-exposed plants exhibited smaller decreases in gas exchange after exposure to -8 °C compared to well-watered plants. Drought also conferred a significant positive effect on leaf, xylem and whole-plant function following exposure to -15 °C; drought-exposed plants exhibited less cell death, greater leaf retention, higher k? and higher rates of gas exchange than well-watered plants. Both drought-exposed and well-watered plants experienced 100% mortality following exposure to -24 °C. By documenting the combined effects of drought and freezing stress, our data provide insight into the mechanisms determining plant survival and performance following freezing and the potential for shifts in L. tridentata abundance and range in the face of changing temperature and precipitation regimes. PMID:20825578

Medeiros, Juliana S; Pockman, William T

2011-01-01

206

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

SciTech Connect

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.

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

1986-01-01

207

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

Microsoft Academic Search

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

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

208

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

Microsoft Academic Search

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,

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

1994-01-01

209

Consistent dielectric properties of the simple point charge and extended simple point charge water models at 277 and 300 K  

Microsoft Academic Search

The dielectric constants (&egr;) of the simple point charge (SPC) and extended simple point charge (SPC\\/E) models of liquid water have been determined at 277 and 300 K using a reaction field (&egr;RF) treatment for the long-range electrostatic interaction. Consistent dielectric constants are obtained by using statistical mechanical perturbation theory, such that the properties of the system correspond to &egr;RF=&egr;,

Paul E. Smith; Wilfred F. van Gunsteren

1994-01-01

210

Passive freeze protection for solar collectors  

Microsoft Academic Search

Freeze damage is an important practical problem for water-type solar collectors. In the past, electric resistance heaters, drain systems, and separate ethylene glycol-water collection loops have commonly been used to prevent freezing. These techniques are effective but involve active components such as controls, heaters, valves, solenoids, pumps, heat exchangers, etc., that increase costs, degrade reliability and\\/or reduce overall efficiency. This

L. W. Bickle

1975-01-01

211

Water Rocket Seen from Educational Point of View  

NASA Astrophysics Data System (ADS)

The water rocket can be easily made of familiar materials. The water rocket flies well beyond expectations. Water rockets are widely used in educational activities for youngsters. The water rocket activities are interesting and educational for people of all ages. I will divide the contents of the water rocket activity into 3 steps and introduce representative examples in each step. I have considered the aim and the effect of each step. The 1st Step is the experience stage. The purpose of this step is to give a lot of children pleasure. In the 1st step, children are encouraged to have curiosity. It is important that the child enjoys the water rocket activity. It gets the children to think that they want to fly a water rocket. It is important to encourage children to have fun during the 1st step so that they will want to continue to the 2nd step. The 2nd Step is the research stage. The water rocket includes elements which show the children various physical phenomena. Through the water rocket activity, the child leans about real rockets. The children also learn the method of scientific experiments. Each child leans and experiences a scientific way of considering things. The water rocket is the optimal research subject for the club activities of school children. The 3rd Step is the creative stage. The child understands the principle of the mechanism. Then, the child improves a water rocket. To realize a variety of ideas, the child continues to repeat these activities in a variety of ways. In this way, the child gains a wide variety of experiences while advancing towards their goal. By using the water rocket as an educational tool we can teach children about many subjects and phenomena, many of which can be seen in daily life.

Takemae, Toshiaki

212

The initial freezing temperature of foods at high pressure.  

PubMed

The Pure water (P,T)-phase diagram is known in the form of empirical equations or tables from nearly a century as a result of Bridgman's work. However, few data are available on other aqueous systems probably due to the difficulty of high-pressure measurements. As an alternative, six approaches are presented here to obtain the food phase diagrams in the range of pressure 0.1-210 MPa. Both empirical and theoretical methods are described including the use of an artificial neural network (ANN). Experimental freezing points obtained at the laboratory of the authors and from literature are statistically compared to the calculated ones. About 400 independent freezing data points of aqueous solutions, gels, and foods are analysed. A polynomial equation is the most accurate and simple method to describe the entire melting curve. The ANN is the most versatile model, as only one model allows the calculation of the initial freezing point of all the aqueous systems considered. Robinson and Stokes' equation is successfully extended to the high pressures domain with an average prediction error of 0.4 degrees C. The choice of one approach over the others depends mainly on the availability of experimental data, the accuracy required and the intended use for the calculated data. PMID:18409115

Guignon, B; Torrecilla, J S; Otero, L; Ramos, A M; Molina-García, A D; Sanz, P D

2008-04-01

213

Freezing of living cells  

SciTech Connect

It can be calculated that a living cell will survive more than 5000 years at -196/sup 0/C. This ability to essentially stop biological time has important implications in medicine and agriculture, and in biological research. In medicine the chief implications are in the banking of transplantable tissues and organs and in in vitro fertilization. In agriculture the applications stem in part from the role of frozen embryos in amplifying the number of calves produced by high quanlity cows. The problem is how can cells survive both the cooling to such very low temperatures and the return to normal temperatures. The answers involve fundamental characteristics of cells such as the permeability of their surface membranes to water and solutes. These characteristics determine whether or not cells undergo lethal internal ice formation and other response during freezing and thawing. 27 refs., 12 figs.

Mazur, P.

1985-01-01

214

MOST CURRENT SECTION 303(D) LISTED WATERS - POINT EVENTS  

EPA Science Inventory

River segments, lakes, and estuaries designated under Section 303(d) of the Clean Water Act. Each State will establish Total Maximum Daily Loads (TMDLs) for these waters. Most Current 303(d) Waterbodies coded onto route.rch (Transport and Coastline Reach) feature of NHD to create...

215

Modelling the effects of water-point closure and fencing removal: a GIS approach.  

PubMed

Artificial water-points in the form of troughs or ground tanks are used to augment natural water supplies within rangelands in many parts of the world. Access to such water-points leads to the development of a distinct ecological sub-system, the piosphere, where trampling and grazing impact modify the vegetation. This study aims to consolidate existing information in a GIS based model to investigate grazing patterns within the landscape. The model focuses on the closure of water-points and removal of fences on Nanya Station, New South Wales, Australia. We found that the manipulation of water-points and fences in one management intervention may change grazing activity in a way different to that which would be experienced if each had been modified separately. Such effects are further modified by the spatial distribution of the water-points and the underlying vegetation. PMID:22542930

Graz, F Patrick; Westbrooke, Martin E; Florentine, Singarayer K

2012-08-15

216

The importance of COâ on freezing point measurements of fluid inclusions: evidence from active geothermal systems and implications for epithermal ore deposition  

Microsoft Academic Search

The authors show how the melting point of ice may be calculated for a fluid of known composites. Fluid inclusion ice-melting data from New Zealand geothermal fields correlate well with values calculated using the equation presented and the measured compositions of discharges from wells from which the inclusion samples were obtained. Loss of the dominant dissolved gas, COâ during boiling

J. W. Hedenquist; R. W. Henley

1985-01-01

217

New particle dependant parameterizations of heterogeneous freezing processes.  

NASA Astrophysics Data System (ADS)

For detailed investigations of cloud microphysical processes an adiabatic air parcel model with entrainment is used. It represents a spectral bin model which explicitly solves the microphysical equations. The initiation of the ice phase is parameterized and describes the effects of different types of ice nuclei (mineral dust, soot, biological particles) in immersion, contact, and deposition modes. As part of the research group INUIT (Ice Nuclei research UnIT), existing parameterizations have been modified for the present studies and new parameterizations have been developed mainly on the basis of the outcome of INUIT experiments. Deposition freezing in the model is dependant on the presence of dry particles and on ice supersaturation. The description of contact freezing combines the collision kernel of dry particles with the fraction of frozen drops as function of temperature and particle size. A new parameterization of immersion freezing has been coupled to the mass of insoluble particles contained in the drops using measured numbers of ice active sites per unit mass. Sensitivity studies have been performed with a convective temperature and dew point profile and with two dry aerosol particle number size distributions. Single and coupled freezing processes are studied with different types of ice nuclei (e.g., bacteria, illite, kaolinite, feldspar). The strength of convection is varied so that the simulated cloud reaches different levels of temperature. As a parameter to evaluate the results the ice water fraction is selected which is defined as the relation of the ice water content to the total water content. Ice water fractions between 0.1 and 0.9 represent mixed-phase clouds, larger than 0.9 ice clouds. The results indicate the sensitive parameters for the formation of mixed-phase and ice clouds are: 1. broad particle number size distribution with high number of small particles, 2. temperatures below -25°C, 3. specific mineral dust particles as ice nuclei such as illite or montmorillonite. Coupled cases of deposition and contact freezing show that they are hardly in competition because of differences in the preferred particle sizes. In the contact mode, small particles are less efficient for collisions as well as less efficient as ice nuclei so that these are available for deposition freezing. On the other hand, immersion freezing is the dominant process when it is coupled with deposition freezing. As it is initiated earlier the formed ice particles consume water vapor for growing. The competition of combined contact and immersion freezing leads to lower ice water contents because more ice particles are formed via the immersion mode. In general, ice clouds and mixed-phase clouds with high ice water fractions are not directly the result of primary ice formation but of secondary ice formation and growth of ice particles at the expense of liquid drops.

Diehl, Karoline; Mitra, Subir K.

2014-05-01

218

Segregation freezing as the cause of suction force for ice lens formation  

Microsoft Academic Search

A new freezing mechanism, called segregation freezing, is proposed to explain the generation of the suction force that draws pore water up to the freezing surface of a growing ice lens. The segregation freezing temperature is derived by applying thermodynamics to a soil mechanics concept that distinguishes the effective pressure from the neutral pressure. The frost-heaving pressure is formulated in

S. Takagi

1978-01-01

219

Freezing Characteristics of Rigid Plant Tissues (Development of Cell Tension during Extracellular Freezing).  

PubMed Central

The freezing characteristics and development of cell tension during extracellular freezing were examined in supercooling stem tissues of riverbank grapes (Vitis riparia) and cold-hardened leaves of live oak (Quercus virginiana) and mountain cranberry (Vaccinium vitis-idaea). Dormant stem xylem and pith tissues of river-bank grapes were resistant to freeze-induced dehydration above the homogeneous nucleation temperature, and they developed cell tension reaching a maximum of 27 MPa. Similarly, extracellular freezing induced cell tension in the leaves of live oak and mountain cranberry. Maximum cell tension in the leaves of live oak was 16.8 MPa and 8.3 MPa in the leaves of mountain cranberry. Following peak tensions in the leaves, a decline in the pressure was observed with progressive freezing. The results suggest that resistance to cell deformation during extracellular freezing due to cell-wall rigidity can lead to reduced cell dehydration and increased cell tension. A relationship to predict freezing behavior in plant tissues based on cell rigidity is presented. Based on cell-water relations and ice nucleation rates, cell-wall rigidity has been shown to effect the freezing characteristics of plant tissues, including freeze-induced dehydration, supercooling, and homogeneous nucleation temperatures.

Rajashekar, C. B.; Burke, M. J.

1996-01-01

220

A Pollution Offset System for Trading NonPoint Source Water Pollution Permits  

Microsoft Academic Search

Water pollution from non-point sources is a global environmental concern. Economists propose tradable permit systems as a\\u000a solution, but they are difficult to implement due to the nature of non-point sources. We present a pollution offset system\\u000a for trading non-point source water pollution permits. Conventional pollution offset systems suffer from thin markets and transaction\\u000a costs. In this paper, we show

R. A. Ranga Prabodanie; John F. Raffensperger; Mark W. Milke

2010-01-01

221

RADON REMOVAL USING POINT-OF-ENTRY WATER TREATMENT TECHNIQUES  

EPA Science Inventory

The purpose of the EPA Cooperative Agreement was to evaluate the performance of POE granular activated carbon (GAC), and diffused bubble and bubble place aeration systems treating a ground water supply containing radon (35,620 ±6,717 pCi/L). The pattern of loading to the uni...

222

RADON REMOVAL USING POINT-OF-ENTRY WATER TREATMENT TECHNIQUES  

EPA Science Inventory

The purpose of this EPA Cooperative Agreement was to evaluate the performance of POE granular activated carbon (GAG), and diffused bubble and bubble place aeration systems treating a ground water supply containing radon (35,620 + or - 6,717 pCi/L. he pattern of loading to the uni...

223

Supercooling of type 1 polar stratospheric clouds: The freezing of submicron nitric acid aerosols having HNO3 mol fractions less than 0.5  

NASA Astrophysics Data System (ADS)

We report the freezing temperatures for nitric acid/water aerosol particles having radii about 0.2 ?m and concentrations in the range 0.24 < xHNO3 < 0.46 (xHNO3 = nitric acid mol fraction). The aerosols supercool by up to 85 K. The droplets having xHNO3 = 0.33 have the highest freezing point in this concentration range; they supercool by 60 K and produce nitric acid dihydrate (NAD) upon freezing. We describe a simplified principal components analysis that improves the detection of the freezing point and allows the identification of the solid that precipitates upon freezing. This procedure shows that for the temperature range and experimental conditions explored, only NAD precipitates in the concentration range 0.33 < xHNO3 < 0.42 and both NAD and nitric acid trihydrate (NAT) precipitate for the range 0.24 < xHNO3 < 0.33. The temperature dependences of our measured freezing points correlate strongly with NAD saturation ratios, but have no relationship with NAT supersaturation at any concentration. Thus NAD nucleates preferentially from supercooled aerosols in this composition range, probably because of kinetic constraints on the nucleation of NAT. We conclude that NAD nucleation is possible during rapid cooling events in the polar stratosphere, if temperatures lower than 185 K are reached. During the freezing of stratospheric aerosol droplets in this concentration range, it seems likely that NAD nucleates first, thereby providing a surface on which NAT may crystallize.

Bertram, A. K.; Dickens, D. B.; Sloan, J. J.

2000-04-01

224

Water molecules and heat transfer modeling in silicon dew point hygrometer  

Microsoft Academic Search

This paper presents the construction and a new complex model of the fabricated silicon dew point hygrometer. The model describes the behavior of water vapor contained in the measured gas (saturated vapor partial pressure, super cooled water phenomenon), water mass transport (condensation and evaporation processes), heat transport across measurement head, silicon dew detector, and regulator characteristics. The model was created

Jerzy Weremczuk

2002-01-01

225

Safely Freezing LTL  

Microsoft Academic Search

We consider the safety fragment of linear temporal logic with the freeze quantifier. The freeze quantifier is used to store a value from an infinite domain in a register for later comparison with other such val- ues. We show that, for one register, satisfiability, refinement and model checking problems are decidable. The main result in the paper is that sat-

Ranko Lazic

2006-01-01

226

Desalting of Seawater by Freezing.  

National Technical Information Service (NTIS)

The economics of the secondary refrigerant freezing process was evaluated with particular emphasis on large freezing plants. It was found that large economies resulted by using normal butane. A study of the secondary refrigerant freezing process using nor...

H. F. Wiegandt J. P. Leinroth P. Harriott

1968-01-01

227

Surface freezing of n-octane nanodroplets  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

228

Freeze drying apparatus  

DOEpatents

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.

Coppa, Nicholas V. (Malvern, PA); Stewart, Paul (Youngstown, NY); Renzi, Ernesto (Youngstown, NY)

2001-01-01

229

Freeze drying method  

DOEpatents

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.

Coppa, Nicholas V. (Malvern, PA); Stewart, Paul (Youngstown, NY); Renzi, Ernesto (Youngstown, NY)

1999-01-01

230

Surface and Interfacial Studies of Ice and Interaction of Water and Polymeric Materials at Temperatures Below 0C. (Adsorption of Water Vapor on Polymers and Freezing of Aqueous Polymer Solutions with Reference to Cryobiology).  

National Technical Information Service (NTIS)

A study was initiated on freezing of Polyvinylpyrrolidone aqueous solutions as a function of polymer concentration and temperature. This resulted in a publication entitled: 'Freezing of Aqueous Polyvinylpyrrolidone Solutions.' Degradation of aqueous polyv...

H. H. G. Jellinek P. J. Clerc S. Y. Fok V. Nagarajan

1969-01-01

231

Heat of Freezing and Melting of Sea Ice.  

National Technical Information Service (NTIS)

Computations are presented which show that the latent heat of freezing ice in equilibrium with sea water is less than that associated with freezing pure water at 0C. The difference is due primarily to a temperature effect that is opposed to some extent by...

D. Anderson

1966-01-01

232

Exploring the Nature of Contact Freezing  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

233

The effects of sulfur mustard exposure and freezing on transdermal penetration of tritiated water through ex vivo pig skin.  

PubMed

The percutaneous absorption of tritiated water ((3)H(2)O) through sulfur mustard (SM) exposed abdominal pig skin was measured using in vitro Franz-type static diffusion cells. The barrier function to water permeation following exposure to liquid SM for 8 min and excision 3h later did not change significantly. A small, but statistically significant difference (P<0.05) in steady state penetration (Jss), permeability coefficient (Kp) and lag time (t(L)) of (3)H(2)O was observed between fresh skin and skin stored frozen (-20 °C) for up to two weeks. Steady-state penetration and Kp values were significantly higher (P < 0.05) in skin stored frozen compared with fresh skin. Fresh naïve skin had an average Kp of 1.65 × 10(-3) cm h(-1), whereas frozen naïve skin was 2.04 × 10(-3) cm h(-1). Fresh SM exposed skin had a mean Kp of 1.72 × 10(-3) cm h(-1), whereas frozen SM exposed skin was 2.31 × 10(-3) cm h(-1). Lag times were also shorter (P<0.05) in skin that had been stored frozen. Frozen, SM-exposed porcine abdominal skin may be used for in vitro penetration studies, but effects of treatment and storage on the barrier layer should be taken into account. PMID:23041075

Payne, O J; Graham, S J; Dalton, C H; Spencer, P M; Mansson, R; Jenner, J; Azeke, J; Braue, E

2013-02-01

234

Physical Impact Evaluation of Chalk Point Generating Station's Cooling Water System on the Patuxent River.  

National Technical Information Service (NTIS)

In July and August 1979 a hydrographic survey using fluorescence tracer techniques was conducted to investigate the physical impact of Chalk Point Generating Station's cooling water discharge on the Patuxent River. The objective was to determine the distr...

R. C. Binkerd H. G. Johnston J. K. Comeau

1979-01-01

235

Intercomparison of Water Triple Point Cells and Standard Platinum Resistance Thermometers.  

National Technical Information Service (NTIS)

Four platinum resistance thermometers and four water triple point cells used in the Primary Standards Temperature Laboratory were tested. Analysis of data showed the thermometers to be interchangeable and the cells to be interchangeable, and that any ther...

R. N. Roberts

1982-01-01

236

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

NASA Astrophysics Data System (ADS)

The isotopic and impurity content of 15 water triple-point cells, manufactured at NMi VSL in the past three years, were investigated. The isotopic analyses were performed on water specimens sampled at three different stages of the manufacturing process. This allowed us to separate and quantify the influence of the source water and of the manufacturing process (distillation, degassing) on the final isotopic composition of the water in the cells. Inductively coupled plasma mass spectrometry (ICPMS) was conducted on selected water samples to investigate the potential contamination of the source water during the manufacturing process, and to evaluate the impact of impurities on the water triple-point temperature. The temperature differences among the manufactured cells were measured, and correlations between the observed differences and the results of isotope and chemical analysis were studied.

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

2007-12-01

237

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...

238

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...

239

Intercomparison of Water Triple-Point Cells. EUROMET Project No. 278.  

National Technical Information Service (NTIS)

The paper presents the results of an intercomparison between a triple point of water cell supplied by the Institut National de Metrologie (France), and cells of similar design which are used as reference fixed points at the National Physical Laboratory. T...

M. V. Chattle J. Butler

1994-01-01

240

Periodic ice banding in freezing colloidal dispersions.  

PubMed

Concentrated colloidal alumina dispersions were frozen in a directional solidification apparatus that provides independent control of the freezing rate and temperature gradient. Two distinct steady-state modes of periodic ice banding were observed in the range of freezing rates examined. For each mode, the wavelength between successive bands of segregated ice decreases with increasing freezing rate. At low freezing rates (0.25-3 ?m s(-1)), the ice segregates from the suspension into ice lenses, which are cracklike in appearance, and there is visible structure in the layer of rejected particles in the unfrozen region ahead of the ice lenses. In this regime, we argue that compressive cryosuction forces lead to the irreversible aggregation of the rejected particles into a close-packed cohesive layer. The temperature in the aggregated layer is depressed below the bulk freezing point by more than 2 °C before the ice lenses are encountered; moreover, this undercooled region appears as a light-colored layer. The magnitude of the undercooling and the color change in this region both suggest the presence of pore ice and the formation of a frozen fringe. The possibility of a frozen fringe is supported by a quantitative model of the freezing behavior. At intermediate freezing rates, around 4 ?m s(-1), the pattern of ice segregation is disordered, coinciding with the disappearance of the dark- and light-colored layers. Finally, at high freezing rates (5-10 ?m s(-1)), there is a new mode of periodic ice banding that is no longer cracklike and is absent of any visible structure in the suspension ahead of the ice bands. We discuss the implications of our experimental findings for theories of ice lensing. PMID:23110707

Anderson, Anthony M; Worster, M Grae

2012-12-01

241

A remote controlled freeze corer for sampling unconsolidated surface sediments  

Microsoft Academic Search

A new coring device is presented which allows the recovery of loose watery surface sediments and the water\\/sediment interface\\u000a byin situ freezing, resulting in well preserved samples. The instrument consists of a tripod with adjustable legs, a hydraulic system,\\u000a an insulated thermos (with two electrical pumps), and a wedge-shaped freeze box. Alcohol chilled with dry ice is the freezing\\u000a agent.

A. F. Lotter; I. Renberg; H. Hansson; R. Stöckli; M. Sturm

1997-01-01

242

A remote controlled freeze corer for sampling unconsolidated surface sediments  

Microsoft Academic Search

A new coring device is presented which allows the recovery of loose watery surface sediments and\\u000athe water\\/sediment interface by in situ freezing, resulting in well preserved samples. The instrument\\u000aconsists of a tripod with adjustable legs, a hydraulic system, an insulated thermos (with two\\u000aelectrical pumps), and a wedge-shaped freeze box. Alcohol chilled with dry ice is the freezing

A. F. Lotter; I. Renberg; H. Hansson; R. Stöckli; M. Sturm

1997-01-01

243

Pointed water vapor radiometer corrections for accurate global positioning system surveying  

Microsoft Academic Search

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

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

1993-01-01

244

Pointed water vapor radiometer corrections for accurate Global Positioning System surveying  

Microsoft Academic Search

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

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

1993-01-01

245

High-freezing-point fuel studies  

NASA Technical Reports Server (NTRS)

Considerable progress in developing the experimental and analytical techniques needed to design airplanes to accommodate fuels with less stringent low temperature specifications is reported. A computer technique for calculating fuel temperature profiles in full tanks was developed. The computer program is being extended to include the case of partially empty tanks. Ultimately, the completed package is to be incorporated into an aircraft fuel tank thermal analyser code to permit the designer to fly various thermal exposure patterns, study fuel temperatures versus time, and determine holdup.

Tolle, F. F.

1980-01-01

246

Use of manometric temperature measurement (MTM) and SMART freeze dryer technology for development of an optimized freeze-drying cycle.  

PubMed

This report provides, for the first time, a summary of experiments using SMART Freeze Dryer technology during a 9 month testing period. A minimum ice sublimation area of about 300 cm(2) for the laboratory freeze dryer, with a chamber volume 107.5 L, was found consistent with data obtained during previous experiments with a smaller freeze dryer (52 L). Good reproducibility was found for cycle design with different type of excipients, formulations, and vials used. SMART primary drying end point estimates were accurate in the majority of the experiments, but showed an over prediction of primary cycle time when the product did not fully achieve steady state conditions before the first MTM measurement was performed. Product resistance data for 5% sucrose mixtures at varying fill depths were very reproducible. Product temperature determined by SMART was typically in good agreement with thermocouple data through about 50% of primary drying time, with significant deviations occurring near the end of primary drying, as expected, but showing a bias much earlier in primary drying for high solid content formulations (16.6% Pfizer product) and polyvinylpyrrolidone (40 kDa) likely due to water "re-adsorption" by the amorphous product during the MTM test. PMID:17853427

Gieseler, Henning; Kramer, Tony; Pikal, Michael J

2007-12-01

247

Effect of soil water repellency on moisture distribution from a subsurface point source  

Microsoft Academic Search

Wetting and redistribution of water in air-dried wettable, slightly repellent, and strongly repellent soils was investigated by tracking the spatial and temporal moisture-content variation in a transparent flow chamber. Water was applied as a subsurface point source. The degree of water repellency had a substantial effect on the plume's shape, dimensions, and internal moisture-content distribution. The high uniform moisture content

Rony Wallach

2010-01-01

248

Two-dimensional freezing criteria for crystallizing colloidal monolayers  

NASA Astrophysics Data System (ADS)

Video microscopy was employed to explore crystallization of colloidal monolayers composed of diameter-tunable microgel spheres. Two-dimensional (2D) colloidal liquids were frozen homogenously into polycrystalline solids, and four 2D criteria for freezing were experimentally tested in thermal systems for the first time: the Hansen-Verlet freezing rule, the Löwen-Palberg-Simon dynamical freezing criterion, and two other rules based, respectively, on the split shoulder of the radial distribution function and on the distribution of the shape factor of Voronoi polygons. Importantly, these freezing criteria, usually applied in the context of single crystals, were demonstrated to apply to the formation of polycrystalline solids. At the freezing point, we also observed a peak in the fluctuations of the orientational order parameter and a percolation transition associated with caged particles. Speculation about these percolated clusters of caged particles casts light on solidification mechanisms and dynamic heterogeneity in freezing.

Wang, Ziren; Alsayed, Ahmed M.; Yodh, Arjun G.; Han, Yilong

2010-04-01

249

Two-dimensional freezing criteria for crystallizing colloidal monolayers.  

PubMed

Video microscopy was employed to explore crystallization of colloidal monolayers composed of diameter-tunable microgel spheres. Two-dimensional (2D) colloidal liquids were frozen homogenously into polycrystalline solids, and four 2D criteria for freezing were experimentally tested in thermal systems for the first time: the Hansen-Verlet freezing rule, the Lowen-Palberg-Simon dynamical freezing criterion, and two other rules based, respectively, on the split shoulder of the radial distribution function and on the distribution of the shape factor of Voronoi polygons. Importantly, these freezing criteria, usually applied in the context of single crystals, were demonstrated to apply to the formation of polycrystalline solids. At the freezing point, we also observed a peak in the fluctuations of the orientational order parameter and a percolation transition associated with caged particles. Speculation about these percolated clusters of caged particles casts light on solidification mechanisms and dynamic heterogeneity in freezing. PMID:20423183

Wang, Ziren; Alsayed, Ahmed M; Yodh, Arjun G; Han, Yilong

2010-04-21

250

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

NASA Astrophysics Data System (ADS)

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 is then applied to a large set of cells, some dating back up to 40 years, and the results are compared with measurements of the cells' triple point temperature. The measurements indicate that the effective ionic conductivity of the impurities in the cells is as low as 2 mS m2 mol-1.

Ballico, Mark

1999-07-01

251

Investigation of PEG crystallization in frozen PEG-sucrose-water solutions. I. Characterization of the nonequilibrium behavior during freeze-thawing.  

PubMed

Our objective was to characterize the nonequilibrium thermal behavior of frozen aqueous solutions containing PEG and sucrose. Aqueous solutions of (i) sucrose (10%, w/v) with different concentrations of PEG (1-20%, w/v), and (ii) PEG (10%, w/v) with different concentrations of sucrose (2-20%, w/v), were cooled to -70 degrees C at 5 degrees C/min and heated to 25 degrees C at 2 degrees C/min in a differential scanning calorimeter. Annealing was performed at temperatures ranging from -50 to -20 degrees C for 2 or 6 h. Similar experiments were also performed in the low-temperature stage of a powder X-ray diffractometer. A limited number of additional DSC experiments were performed wherein the samples were cooled to -100 degrees C. In unannealed systems with a fixed sucrose concentration (10%, w/v), the T'g decreased from -35 to -48 degrees C when PEG concentration was increased from 1% to 20% (w/v). On annealing at -25 degrees C, PEG crystallized. This was evident from the increase in T'g and the appearance of a secondary melting endotherm in the DSC. Low-temperature XRD provided direct evidence of PEG crystallization. Annealing at temperatures water system, reflecting progressive PEG crystallization. A second glass transition at approximately -65 degrees C was evident in unannealed systems [10%, w/v sucrose and 10 (or 20%), w/v PEG] cooled to -100 degrees C. Investigation of the nonequilibrium behavior of frozen PEG-sucrose-water ternary system revealed phase separation in the freeze-concentrate. Annealing facilitated PEG crystallization. PMID:20091827

Bhatnagar, Bakul S; Martin, Susan M; Teagarden, Dirk L; Shalaev, Evgenyi Y; Suryanarayanan, Raj

2010-06-01

252

Interaction between loading, freeze–thaw cycles, and chloride salt attack of concrete with and without steel fiber reinforcement  

Microsoft Academic Search

In this paper, the deterioration of concrete subjected to the combined action of four-point bending—loading, freeze–thaw cycles, and chloride salt attack—is discussed. Test results show that concrete tested in chloride salt solution scaled much more severely than in fresh water, and its weight loss in chloride salt solution was twice that in water. However, dynamic modulus of elasticity (DME) of

Ru Mu; Changwen Miao; Xin Luo; Wei Sun

2002-01-01

253

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

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

254

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

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

255

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

Code of Federal Regulations, 2011 CFR

...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...

2011-07-01

256

Development of a Freeze-Tolerant Solar Water Heater Using Crosslinked Polyethylene as a Material of Construction. Progress Report, January 5, 1977:--March 15, 1977.  

National Technical Information Service (NTIS)

Fifteen 10 ft coils of crosslinked tubing have been subjected to repeated freezing and thawing. The composition of the crosslinked polyethylene and the stress in the wall of the tubing (i.e., ''hoop stress'') are parameters which are being studied to find...

J. M. Bradley

1977-01-01

257

Scram or Freeze  

NSDL National Science Digital Library

In this outdoor activity and animal-role-play game, learners discover and uncover the hidden world of "cryptozoa"âorganisms such as spiders, salamanders and slugs that live under objects, like rocks and fallen tree trunks, or in concealed places. When uncovered, some cryptozoa scurry for cover ("scram"), while others remain motionless ("freeze"). Both behaviors help uncovered organisms escape from predators. In the game, learners take the roles of predator or prey and get to scram and freeze, and even growl, until all the prey are caught or reach "shelter." Learners also conduct a cryptozoa survey, by carefully upturning pieces of wood, leaves and rock to find and collect hidden animals. At the end, learners return all organisms to their original positions. The PDF includes safety precautions to protect both learners and the animals they uncover. To adapt the game for hearing impaired learners, instruction signs reading "scram" and "freeze" could be used instead of verbal instructions.

Science, Lawrence H.

1981-01-01

258

Percolation with Constant Freezing  

NASA Astrophysics Data System (ADS)

We introduce and study a model of percolation with constant freezing (PCF) where edges open at constant rate 1 , and clusters freeze at rate ? independently of their size. Our main result is that the infinite volume process can be constructed on any amenable vertex transitive graph. This is in sharp contrast to models of percolation with freezing previously introduced, where the limit is known not to exist. Our interest is in the study of the percolative properties of the final configuration as a function of ? . We also obtain more precise results in the case of trees. Surprisingly the algebraic exponent for the cluster size depends on the degree, suggesting that there is no lower critical dimension for the model. Moreover, even for ?

Mottram, Edward

2014-04-01

259

Percolation with Constant Freezing  

NASA Astrophysics Data System (ADS)

We introduce and study a model of percolation with constant freezing ( PCF) where edges open at constant rate , and clusters freeze at rate independently of their size. Our main result is that the infinite volume process can be constructed on any amenable vertex transitive graph. This is in sharp contrast to models of percolation with freezing previously introduced, where the limit is known not to exist. Our interest is in the study of the percolative properties of the final configuration as a function of . We also obtain more precise results in the case of trees. Surprisingly the algebraic exponent for the cluster size depends on the degree, suggesting that there is no lower critical dimension for the model. Moreover, even for , it is shown that finite clusters have algebraic tail decay, which is a signature of self organised criticality. Partial results are obtained on , and many open questions are discussed.

Mottram, Edward

2014-06-01

260

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

NASA Astrophysics Data System (ADS)

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 from 13.8033 K to 1234.93 K. The Consultative Committee for Thermometry (CCT) decided at its 21st meeting in 2001 to carry out a comparison of water triple point cells and charged the BIPM with its organization. Water triple point cells from 20 national metrology institutes were carried to the BIPM and were compared with highest accuracy with two reference cells. The small day-to-day changes of the reference cells were determined by a least-squares technique. Prior to the measurements at the BIPM, the transfer cells were compared with the corresponding national references and therefore also allow comparison of the national references of the water triple point. This report presents the results of this comparison and gives detailed information about the measurements made at the BIPM and in the participating laboratories. It was found that the transfer cells show a standard deviation of 50 µK the difference between the extremes is 160 µK. The same spread is observed between the national references. The most important result of this work is that a correlation between the isotopic composition of the cell water and the triple point temperature was observed. To reduce the spread between different realizations, it is therefore proposed that the definition of the kelvin should refer to water of a specified isotopic composition. The CCT recommended to the International Committee of Weights and Measures (CIPM) to clarify the definition of the kelvin in the SI brochure by explicitly referring to water with the isotopic composition of Vienna Standard Mean Ocean Water (VSMOW). The CIPM accepted this recommendation and the next edition of the SI brochure will include this specification. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

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

2006-01-01

261

Water and nitrogen distribution as affected by fertigation of ammonium nitrate from a point source  

Microsoft Academic Search

The simultaneous distribution of water, nitrate, and ammonium from a point source discharging an ammonium nitrate (NH4NO3) solution was measured using the gravimetric method. A 15° wedge-shaped plexiglass container was used to represent one twenty-fourth of the complete cylinder. The variables affecting water and solute distributions, including application rate, input concentration, and applied volume were investigated and their effects are

Jiusheng Li; Jianjun Zhang; Li Ren

2003-01-01

262

Freezing of Lennard-Jones-type fluids  

SciTech Connect

We put forward an approximate method to locate the fluid-solid (freezing) phase transition in systems of classical particles interacting via a wide range of Lennard-Jones-type potentials. This method is based on the constancy of the properly normalized second derivative of the interaction potential (freezing indicator) along the freezing curve. As demonstrated recently it yields remarkably good agreement with previous numerical simulation studies of the conventional 12-6 Lennard-Jones (LJ) fluid [S.A.Khrapak, M.Chaudhuri, G.E.Morfill, Phys. Rev. B 134, 052101 (2010)]. In this paper, we test this approach using a wide range of the LJ-type potentials, including LJ n-6 and exp-6 models, and find that it remains sufficiently accurate and reliable in reproducing the corresponding freezing curves, down to the triple-point temperatures. One of the possible application of the method--estimation of the freezing conditions in complex (dusty) plasmas with ''tunable'' interactions--is briefly discussed.

Khrapak, Sergey A. [Max-Planck-Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany); Joint Institute for High Temperatures, 125412 Moscow (Russian Federation); Chaudhuri, Manis; Morfill, Gregor E. [Max-Planck-Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany)

2011-02-07

263

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

NASA Astrophysics Data System (ADS)

To investigate an ideal container material for the triple point of water (TPW) cell and to reduce the influence to the triple-point temperature, due to the deviation of the isotopic composition of the water, both borosilicate and fused-quartz glass shelled TPW cells with isotopic composition substantially matching that of Vienna Standard Mean Ocean Water (VSMOW) were developed and tested. Through a specially designed manufacturing system, the isotopic composition, ?D and ?18 O, of the water in the TPW cell could be controlled within ±10‰ (per mil) and ±1.5‰, respectively, resulting in control of the isotopic temperature correction to better than ± 8 ?K. Through an ampoule attached to the cell, the isotopic composition of the water in the cell could be individually analyzed . After manufacture, the initial triple-point temperatures of the two types of cell were measured and compared to assess the quality of the cells and manufacturing process. Cells fabricated with the new system agree within 50 ?K. Two innovatively designed borosilicate and fused-quartz TPW cells were made, each with six attached ampoules. One ampoule was removed every 6 months to track any changes in purity of the water over time.

Zhao, M.; Strouse, G. F.

2007-12-01

264

Animal Anti-Freeze  

NSDL National Science Digital Library

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.

Science, Lawrence H.

1982-01-01

265

Visualization of freezing damage.  

PubMed

Freeze-cleaving can be used as a direct probe to examine the ultrastructural alterations of biological material due to freezing. We examined the thesis that at least two factors, which are oppositely dependent upon cooling velocity, determine the survival of cells subjected to freezing. According to this thesis, when cells are cooled at rates exceeding a critical velocity, a decrease in viability is caused by the presence of intracellular ice; but cells cooled at rates less than this critical velocity do not contain appreciable amounts of intracellular ice and are killed by prolonged exposure to a solution that is altered by the presence of ice. As a test of this hypothesis, we examined freeze-fractured replicas of the yeast Saccharomyces cerevisiae after suspensions had been cooled at rates ranging from 1.8 to 75,000 degrees C/min. Some of the frozen samples were cleaved and replicated immediately in order to minimize artifacts due to sample handling. Other samples were deeply etched or were rewarmed to -20 degrees C and recooled before replication. Yeast cells cooled at or above the rate necessary to preserve maximal viability ( approximately 7 degrees C/min) contained intracellular ice, whereas cells cooled below this rate showed no evidence of intracellular ice. PMID:4572921

Bank, H; Mazur, P

1973-06-01

266

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

NASA Astrophysics Data System (ADS)

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 from the water activity at the melting point of the solution, though films of the longer chain alcohols may undergo structural changes at higher salt concentrations which cause a deviation from the constant offset. The heterogeneous nucleation rate coefficient, averaged over all solutions, alcohols, and droplet sizes is 6.0 × 104 +/- 4.0 × 104 cm-2 s-1, with no dependence on any of those parameters.

Cantrell, Will; Robinson, Carly

2006-04-01

267

Infiltration from a surface point source and drip irrigation 1. The midpoint soil water pressure  

Microsoft Academic Search

Bresler [1978] proposed a procedure for drip irrigation design which is focused on the midpoint soil water pressure hc. We present a practical field test of this approach in order to evaluate the validity of the underlying assumptions. The simulated hc values were obtained from Raats' [1971] steady state theory for 32 points in the field where the hydraulic conductivity

P. Revol; M. Vauclin; G. Vachaud; B. E. Clothier

1997-01-01

268

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...

269

Intercomparison of water triple point cells and standard platinum resistance thermometers  

NASA Astrophysics Data System (ADS)

Four platinum resistance thermometers and four water triple point cells used in the Primary Standards Temperature Laboratory were tested. Analysis of data showed the thermometers to be interchangeable and the cells to be interchangeable, and that any thermometer can be used with any cells.

Roberts, R. N.

1982-12-01

270

Development of Information Focal Points (IFPs) on Community Water Supply in Rural Areas  

Microsoft Academic Search

At the end of 1998 a training workshop was organized by the IRC International Water and Sanitation Centre in The Hague, The Netherlands, with the aim of establishing Information Focal Points (IFPs) within a number of organizations. The partner organizations were NETWAS International in Nairobi, Kenya, WASEP in Gilgit, Northern Areas of Pakistan, CINARA in Cali, Colombia, and the Mvula

Nigel Browne; Isaack O. Oenga; Paul Saka Chikombe; Tameez Ahmad; Haider Razza; Rodrigo Galvis Castano; Kate Skinner; Kerry Harris

2003-01-01

271

Issues in Ecology, Issue 03: Non Point Pollution of Surface Waters  

NSDL National Science Digital Library

This report addresses pollution of aquatic ecosystems that originate from multiple unidentified sources or non point sources. Non point sources of phosphorus and nitrogen are of concern as they cause eutrophication or excessive enrichment of surface waters. Effects and remediation strategies are discussed. Non point sources, such as agricultural, urban and atmospheric ones are discussed. Management techniques to reduce excess nutrient transport across landscapes and into bodies of water are explained. The report discusses the need to establish controversial Thresholds of unacceptable soil contamination. Issues in Ecology is an ongoing series of reports designed to present major ecological issues in an easy-to-read manner. This Issue summarizes the consensus of a panel of scientific experts based on the information that was current and available at the time of its publication in 1998.

Smith, Val

2010-02-16

272

Natural Wetlands Mediate Non-point Source Water Pollution From Irrigated Pastures  

NASA Astrophysics Data System (ADS)

Non-point source discharge from grazed pastures may be high in nutrients, sediment, and pathogens, three major contributors to water quality impairment in California. Intercepting pollution at its source and managing water quality within the landscape are essential to maintaining healthy downstream waters. We investigated the efficacy of flow-through wetlands interspersed throughout the agricultural landscape to reduce non-point source pollution of tailwater from cattle-grazed, irrigated pastures in the Sierra Nevada Foothills of California. Wetlands are known to positively impact water quality through ecological processes such as filtration, sedimentation, microbial transformations and plant uptake of nutrients. Influent and effluent water of small (0.25 ha), natural wetlands located downstream from flood irrigated pastures was analyzed for Escherichia coli, NO3-N, total N, total suspended solids (TSS), total P, and dissolved organic carbon (DOC) throughout two summer irrigation seasons (June to October). We compared reductions of sediment, nutrients and E. coli provided by a healthy, non-degraded wetland with reductions from flow through a channelized, degraded wetland. Large reductions in E. coli (>75%) and TSS (>50%) were observed in water exiting the healthy wetland while nutrient and DOC (~ 20%) concentrations were less affected by flow through the wetland. The channelized wetland provided smaller reductions in all constituents than did the non-degraded wetland. Results from this study demonstrate that small flow-through wetlands can improve water quality through the attenuation of E. coli and suspended sediments, and to a lesser degree DOC and nutrients.

Knox, K.; Dahlgren, R. A.; Tate, K. W.

2005-12-01

273

Polymorphism of Ganglioside-Water Systems: a New Class of Micellar Cubic Phases. Freeze-Fracture Electron Microscopy and X-Ray Scattering Studies  

NASA Astrophysics Data System (ADS)

The (T, c)-dependent phase diagrams of two gangliosides, GM1 and GM1(acetyl), have been explored, in spite of the frequent occurrence of metastable states. In GM1 two lamellar, one hexagonal and two cubic (aspects sharp 5 and 13) phases were identified, in addition to the isotropic micellar solution. In GM1(acetyl) two of the phases are cubic (aspects sharp 8 and 13), one is the fluid isotropic solution. The structure of the lamellar and the hexagonal phases are trivial. The structure of the cubic phases was determined using a combination of freeze-fracture electron microscope and X-ray scattering experiments. The three cubic phases consist of lipid micelles of type I (oil-in-water); in two of the phases (Q^{225} and Q^{229}) the micelles are all identical and of quasi-spherical shape. Phase Q^{223} was previously known to contain two types of micelles, one quasi-spherical, the other slightly flattened. The radii of the micelles determined from the dimensions of the electron density troughs were consistent with the chemical data. In keeping with what is known of the micellar solutions, the size of the micelles of the cubic phases of GM1(acetyl) is compatible with a spherical shape, whereas the micelles of GM1 seem to be somewhat too large to be compatible with the length of the molecules and with a spherical shape. Such a wealth of micellar cubic phases is unusual in lipid-water systems. Le diagramme de phases de deux gangliosides, GM1 et GM1(acétyl), a été exploré malgré la présence d'états métastables. On a identifié les phases suivantes : dans GM1 deux phases lamellaires, une hexagonale, deux cubiques (aspects sharp 5 et 13), une solution micellaire ; dans GM1(acetyl) deux phases cubiques (aspects sharp 8 et 13) et une solution micellaire. La structure des phases lamellaires et hexagonale est triviale. La structure des phases cubiques a été déterminée par l'usage combiné de microscopie électronique et de diffraction des rayons X. Les trois phases cubiques sont formées de micelles de type I (huile dans l'eau) ; dans deux de ces phases (Q^{225} et Q^{229}) les micelles sont toutes identiques et de forme presque sphérique. La phase Q^{223} est connue ; elle est formée par deux types de micelles, les unes presque sphériques, les autres légèrement aplaties. Les rayons des micelles déterminés sur les cartes de densité électronique sont en excellent accord avec les données chimiques. Dans les deux phases cubiques la taille des micelles de GM1(acétyl) est compatible avec une forme sphérique, tandis que les micelles de GM1 semblent être un peu trop grandes par rapport à la longueur des molécules : ces observations sont en excellent accord avec ce que l'on sait sur les solutions micellaires de ces deux lipides. Cette richesse de phases cubiques micellaires est inhabituelle dans les systèmes lipide-eau.

Gulik, Annette; Delacroix, Hervé; Kirschner, Günther; Luzzati, Vittorio

1995-03-01

274

Isotopic Tracers for Delineating Non-Point Source Pollutants in Surface Water  

SciTech Connect

This study tested whether isotope measurements of surface water and dissolved constituents in surface water could be used as tracers of non-point source pollution. Oxygen-18 was used as a water tracer, while carbon-14, carbon-13, and deuterium were tested as tracers of DOC. Carbon-14 and carbon-13 were also used as tracers of dissolved inorganic carbon, and chlorine-36 and uranium isotopes were tested as tracers of other dissolved salts. In addition, large databases of water quality measurements were assembled for the Missouri River at St. Louis and the Sacramento-San Joaquin Delta in California to enhance interpretive results of the isotope measurements. Much of the water quality data has been under-interpreted and provides a valuable resource to investigative research, for which this report exploits and integrates with the isotope measurements.

Davisson, M L

2001-03-01

275

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

PubMed

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

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

2011-06-01

276

Qualification of rangeland degradation using plant life history strategies around watering points in southern Tunisia.  

PubMed

In this reserch we review the effects of animal activities on plant life history strategies (CRS) around watering points using phyto-ecological studies and vegetation cover data. The objective of this study was to understand the impact of disturbance degree simulated by distance from wells on CRS strategies (Grime types). The main results indicate that annualisation is a reality. We show the dominance of RS-species in the more disturbed sites (nearest transect from watering points), CRS- and CS-species at medium disturbance and CS- and S-species in lower disturbance sites (further from water). The floristic homogenisation is discernible at long period of exploitation. With lower grazing disturbance, Stipagrostis pungens can appropriately survive but it cannot tolerate the high degradation levels. PMID:19069921

Tarhouni, Mohamed; Belgacem, Azaiez Ouled; Neffati, Mohamed; Henchi, Belgacem

2007-04-15

277

Developing a Framework to Estimate Land Use Export Coefficients for the Modelling of Point and Non Point Source Pollutant Loads into Water Bodies  

Microsoft Academic Search

Several methodologies have been developed to estimate point and non point source pollution loadings into water bodies. These methodologies range from field data collection to modelling studies. Modelling techniques ranges from simple export coefficient models, regression models to complex mechanistic models. All export coefficients models and some complex mechanistic models have frequently relied on land use based export coefficients to

S. Shrestha; F. Kazama

2006-01-01

278

Effect of long-term freezing and freeze-thaw cycles on indigenous and inoculated microorganisms in dewatered blackwater.  

PubMed

Wastewater treatment in many Arctic regions is inadequate, even nonexisting. Natural freezing of wastewater in those areas may be beneficial for reduction of microorganisms. The aim of this study was to investigate the effect of long-term freezing, and repeated freezing and thawing, on indigenous coliforms, fecal streptococci, and antibiotic-resistant (AR) bacteria, and inoculated Salmonella Enteriditis and E. coli bacteriophage ?X174 in dewatered blackwater. At the end of the long-term freezing experiment (10 months), an MPN recovery study was done, including the microbial groups that had shown the largest reduction, using tryptone soy broth at incubation temperatures of 10 and 20 °C overnight for the coliforms and AR bacteria, and buffered peptone water at incubation temperature of 37 °C for 18-20 h for Salmonella. Fecal streptococci were more resistant to long-term freezing than the coliform group. Total number of AR bacteria decreased slowly but constantly over the 10-month freezing period. Salmonella rapidly decreased and were nondetectable within a week but exhibited some recovery after 10 months of freezing, whereas limited or no recovery of coliforms and AR-bacteria was detected. Bacteriophages showed limited reduction during the long-term freezing. Repeated freezing and thawing increased the reduction of all tested microbial groups markedly. PMID:23113759

Gunnarsdóttir, Ragnhildur; Müller, Karoline; Jensen, Pernille Erland; Jenssen, Petter Deinboll; Villumsen, Arne

2012-11-20

279

33 CFR 334.412 - Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted area.  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 2013-07-01 false Albemarle Sound, Pamlico Sound, Harvey Point and adjacent waters, NC; restricted...RESTRICTED AREA REGULATIONS § 334.412 Albemarle Sound, Pamlico Sound, Harvey Point and adjacent...

2013-07-01

280

Aquaporin-mediated improvement of freeze tolerance of Saccharomyces cerevisiae is restricted to rapid freezing conditions.  

PubMed

Previous observations that aquaporin overexpression increases the freeze tolerance of baker's yeast (Saccharomyces cerevisiae) without negatively affecting the growth or fermentation characteristics held promise for the development of commercial baker's yeast strains used in frozen dough applications. In this study we found that overexpression of the aquaporin-encoding genes AQY1-1 and AQY2-1 improves the freeze tolerance of industrial strain AT25, but only in small doughs under laboratory conditions and not in large doughs under industrial conditions. We found that the difference in the freezing rate is apparently responsible for the difference in the results. We tested six different cooling rates and found that at high cooling rates aquaporin overexpression significantly improved the survival of yeast cells, while at low cooling rates there was no significant effect. Differences in the cultivation conditions and in the thawing rate did not influence the freeze tolerance under the conditions tested. Survival after freezing is determined mainly by two factors, cellular dehydration and intracellular ice crystal formation, which depend in an inverse manner on the cooling velocity. In accordance with this so-called two-factor hypothesis of freezing injury, we suggest that water permeability is limiting, and therefore that aquaporin function is advantageous, only under rapid freezing conditions. If this hypothesis is correct, then aquaporin overexpression is not expected to affect the leavening capacity of yeast cells in large, industrial frozen doughs, which do not freeze rapidly. Our results imply that aquaporin-overexpressing strains have less potential for use in frozen doughs than originally thought. PMID:15184134

Tanghe, An; Van Dijck, Patrick; Colavizza, Didier; Thevelein, Johan M

2004-06-01

281

Simulation of quantum zero-point effects in water using a frequency-dependent thermostat  

NASA Astrophysics Data System (ADS)

Molecules like water have vibrational modes with a zero-point energy well above room temperature. As a consequence, classical molecular dynamics simulations of their liquids largely underestimate the energy of modes with a higher zero-point temperature, which translates into an underestimation of covalent interatomic distances due to anharmonic effects. Zero-point effects can be recovered using path integral molecular dynamics simulations, but these are computationally expensive, making their combination with ab initio molecular dynamics simulations a challenge. As an alternative to path integral methods, from a computationally simple perspective, one would envision the design of a thermostat capable of equilibrating and maintaining the different vibrational modes at their corresponding zero-point temperatures. Recently, Ceriotti [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.102.020601 102, 020601 (2009)] introduced a framework to use a custom-tailored Langevin equation with correlated noise that can be used to include quantum fluctuations in classical molecular dynamics simulations. Here we show that it is possible to use the generalized Langevin equation with suppressed noise in combination with Nose-Hoover thermostats to efficiently impose a zero-point temperature on independent modes in liquid water. Using our simple and inexpensive method, we achieve excellent agreement for all atomic pair correlation functions compared to the path integral molecular dynamics simulation.

Ganeshan, Sriram; Ramírez, R.; Fernández-Serra, M. V.

2013-04-01

282

Freezing and anoxia tolerance of slugs: a metabolic perspective.  

PubMed

Freezing survival was assessed in three species of terrestrial slugs, a holarctic but native North American species, Deroceras laeve, and two species introduced from Europe, D. reticulatum and Arion circumscriptus. The introduced species showed very poor freezing survival. Supercooling points of the introduced species were quite high ( approximately -3 degrees C) and their freezing survival was very poor, limited to short-term freezing at -1.2 to -1.5 degrees C and low ice contents (23-44%). D. laeve showed a significant elevation of supercooling point between slugs collected in the autumn (-4.8 degrees C +/- 0.5) and those collected early in the spring (-3.1 degrees C +/- 0.4). This species also showed substantial freezing survival which was greater for spring-collected slugs (100% survival of 1 h freezing at -2 degrees C with an ice content of 65%) than for autumn animals (100% survival for 1 h at -1 degrees C with approximately 40% ice). Carbohydrate and amino acid responses to freezing and anoxia exposures were compared in the two Deroceras species. D. laeve showed a strong hyperglycemic response to freezing, a 100-fold increase in glucose levels that suggested that glucose may have a cryoprotective function in this species. D. reticulatum did not accumulate glucose and neither species produced glycerol or lactate. Both species showed typical responses to anoxia (aspartate and glutamate catabolism, alanine and succinate accumulation) and D. laeve also showed this pattern during freezing, suggesting a natural switch to anaerobiosis to support freezing survival. PMID:17628806

Storey, Kenneth B; Storey, Janet M; Churchill, Thomas A

2007-11-01

283

Effect of soil water repellency on moisture distribution from a subsurface point source  

NASA Astrophysics Data System (ADS)

Wetting and redistribution of water in air-dried wettable, slightly repellent, and strongly repellent soils was investigated by tracking the spatial and temporal moisture-content variation in a transparent flow chamber. Water was applied as a subsurface point source. The degree of water repellency had a substantial effect on the plume's shape, dimensions, and internal moisture-content distribution. The high uniform moisture content in the repellent soil's plume surrounded by a narrow transition layer within which moisture content was sharply decreasing indicates that unstable flow shapes a finger-like wetting front. Moisture redistribution in the repellent soils was limited and took place mainly in the vertical direction. The repellent soils were wetted immediately, very likely by local positive pressure buildup induced by the hydraulic resistance imposed by the initial >90° contact angle. The plume shape dimensions and internal moisture-content distribution should be considered in the design and operation of subsurface drip irrigation in water-repellent soils.

Wallach, Rony

2010-08-01

284

Pointed water vapor radiometer corrections for accurate global positioning system surveying  

NASA Astrophysics Data System (ADS)

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 toward GPS satellites to correct for azimuthal variations in water vapor. We report 2.6 mm vertical precision on a 50-km baseline for 19 solution days. Kalman filter or least-square corrections to the same data do not account for azimuthal distribution of water vapor and are degraded by 70%.

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

1993-12-01

285

Application of cloud point extraction for the determination of pyrene in natural water.  

PubMed

Triton X-114 (Triton X-114) surfactant separates into two isotropic phases at room temperature and can be successfully used in cloud point extraction for the analysis of polycyclic aromatic hydrocarbons (PAHs). We studied which type of container is the most suitable for PAHs extraction with this method and how the water affects PAH recovery. We used a generator and mini-centrifuge with a cloud point method to determine pyrene levels in water in the field. An on-site thermostat can be used along with pouring hot water from a canteen into a plastic bucket to keep the temperature stable. Significant losses of pyrene due to adsorption onto the container wall can be minimized by storing water samples in glass containers. Variation in critical micelle concentration (cmc) can be avoided by bringing the water temperature to 40 degrees C for 5 minutes. These methods allowed pyrene to be determined in a remote tropical peat swamp area in Central Kalimantan, Indonesia. PMID:19330948

Pongpiachan, Siwatt

2009-03-01

286

Preparation at the BIPM for a Key Comparison of Water Triple-Point Cells  

NASA Astrophysics Data System (ADS)

Under the Mutual Recognition Arrangement (MRA), the metrological equivalence of national measurement standards is determined from a set of key comparisons chosen and organized by the Consultative Committees of the International Committee for Weights and Measures (CIPM). At its 21st meeting, in September 2001, the Consultative Committee for Thermometry (CCT) decided to carry out a key comparison of water triple-point cells, which is designated as CCT-K7 in the framework of the MRA. In this paper, we present: • the results obtained during the previous comparison of water triple point cells in 1995; • the comparison scheme chosen for this key comparison; • recent improvements to the measurement system of the BIPM; • the results of the evaluation of some uncertainty components of the new measurement system; and • finally, a provisional uncertainty budget for the comparison.

Solve, S.; Stock, M.

2003-09-01

287

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

PubMed Central

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.

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

2009-01-01

288

Ground-water conditions at the Veterans Facility, Castle Point, New York  

USGS Publications Warehouse

The rock aquifers in the vicinity of the Castle Point Veterans Hospital yield limited quantities of water which, in general, are sufficient for domestic and farm purposes only. The possibility of obtaining the stated quantity requirements of about 200,000 gallons daily or more from the bedrock formations seems poor with the exception of the Wappinger limestone underlying the Fishkill Valley three miles to the south.

Brashears, M. L., Jr.

1950-01-01

289

Mechanisms of Freezing lnjuly in Cellular Leve  

NASA Astrophysics Data System (ADS)

The mechanisms of freezing injury in living cells were reviewed. The freezing injury takes place by at least two different factors depending upon cooling rate, those are intracellular freezing and extracellular freezing. The freezing injury caused by extracellular freezing also takes place by two different factors, those are direct and indirect effects by the formation of extracellular ice. These different stresses by freezing cause different damages on the plasma membranes in the same cell. Furthermore, freezing of different cell results in different form of membrane damage. Thus, the occurrence of freezing injury takes place by diverse mechanisms depending upon not only different freezing stresses but also difference of cell type.

Fujikawa, Seizo

290

POINT-OF-USE/POINT-OF-ENTRY SYSTEMS FOR REMOVING VOCS (VOLATILE ORGANIC COMPOUNDS) FROM DRINKING WATER  

EPA Science Inventory

Where available, centralized treatment is the recommended method for producing potable water. Many homes, however, can not connect to a centralized water treatment system leaving them with no other alternative but to treat their own water. POU/POE systems are effective for removi...

291

Oocyte freezing: here to stay?  

PubMed

Oocyte freezing is an established technology but, in contrast to embryo freezing, it has very limited application in clinical IVF programmes. Is there a chance that oocyte freezing will become an integrated routine in assisted reproductive technology? The delicate cytological architecture of the oocyte with a cold-sensitive spindle and a hardening zona have made the frozen oocyte 'unwanted' in assisted reproductive technology. Nevertheless, empirical improvements in freezing protocols and the use of ICSI for fertilization have led to an increasing number of live births. This mitigates against a simple ban on oocyte freezing. While efficiency of oocyte freezing can certainly be further improved by basic research, it is clear that there are humanitarian reasons for considering oocyte freezing as a future fully utilized assisted reproductive technology. The storage of the female genome as a particulate entity can provide an alternative in case of moral, ethical, legal or religious concerns about embryo freezing. Oocyte freezing can also offer hope for oocyte donation and preservation of fertility for women facing ovarian loss. The message is one of cautious optimism when looking for a place for oocyte freezing in routine assisted reproductive technology. PMID:14640378

Van der Elst, Josiane

2003-01-01

292

Damage Evaluation on Freeze-Thawing Process of Food by Using NMR  

NASA Astrophysics Data System (ADS)

Freeze-thawing process gives significant damages for food structure. Several new techniques have been attempted for quantitative evaluation of the damages. In this study, using NMR (nuclear magnetic resonance) with a stimulated echo method, restricted diffusion phenomena of water molecules was measured for damaged food (onion and tuna) tissues that were subjected to the repeat of freeze-thawing, Through experiments, water permeability of tissue membrane was calculated. The water permeability of fresh tissues for onion showed clearly restricted diffusion, but after freeze-thawing, it disappeared. On the other hand, the water permeability of fresh tuna tissue was small significantly, even though it was a little higher after freeze-thawing. After all, the damage level after freeze-thawing showed a significant difference between onion and tuna. These results support the view that plant tissue is very sensitive to freeze-thawing and that the water permeability of plant is much lower than that of animal.

Andou, Hiroko; Fukuoka, Mika; Miyawaki, Osato; Suzuki, Toru

293

Point-of-use water disinfection using UV light-emitting diodes to reduce bacterial contamination.  

PubMed

The treatment process described in this research explores the impact of exposing water samples containing fecal coliforms to the radiation produced by single ultraviolet (UV) light-emitting diodes (LEDs) operating at 265 nm. UV LEDs are long lasting, compact in size and produce more efficient light output than traditional mercury-vapour bulbs, making them ideal for application in point-of-use disinfection systems, such as in remote areas. In this study, contaminated water samples containing either a pure culture of Escherichia coli or tertiary effluent from the City of Regina Wastewater Treatment Plant were used to study the application and efficiency of using UV LEDs for water disinfection. The results indicate that bacterial inactivation was achieved in a time-dependent manner, with 1- and 2.5-log E. coli reductions in water following 20 and 50 min of UV LED exposure, respectively. Ultraviolet radiation was less effective in reducing coliform bacteria in wastewater samples due to the elevated turbidity levels. Further work remains to be completed to optimize the application of UV LEDs for point-of-use disinfection systems; however, the results from this study support that bacterial inactivation using UV LEDs is possible, meriting further future technological development of the LEDs. PMID:23423870

Nelson, Kristina Y; McMartin, Dena W; Yost, Christopher K; Runtz, Ken J; Ono, Takaya

2013-08-01

294

The Impact of Isotopic Concentration, Impurities, and Cell Aging on the Water Triple-Point Temperature  

NASA Astrophysics Data System (ADS)

In 2005, the National Institutes of Standards and Technology (NIST) and Fluke’s Hart Scientific Division initiated a study to validate the isotopic correction algorithm applied to the realization temperature of triple point of water (TPW) cells. Additionally, the study quantified the impact of water sample impurities on the TPW cell realization temperature. For this study, eight TPW cells containing water of the same nominal isotopic concentration as Vienna Standard Mean Ocean Water (VSMOW) were used. Five of the cells were manufactured with fused-quartz envelopes and the remaining three with borosilicate envelopes. One TPW cell of each type was uniquely designed so that water samples could be periodically removed to analyze the isotopic composition and to monitor any changes in water purity with time and thereby correlate changes in composition with changes in realization temperature. The borosilicate TPW cells gave an average drift of -13 ?K · yr-1 and the more stable fused-quartz TPW cells gave an average drift of -2 ?K · yr-1.

Strouse, G. F.; Zhao, M.

2007-12-01

295

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

Microsoft Academic Search

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

M. W. Woo; A. S. Mujumdar

2010-01-01

296

Frost action of freezing ground surrounding underground storage of a cold liquid  

NASA Astrophysics Data System (ADS)

A small tank in the shape of a cylinder 80 cm in diameter and 50 cm in depth was placed in a basin, filled with a silty soil, of the frost test field in Tomakomai, Hokkaido Japan, with its top at the same level as the ground surface in the basin. The double wall (two steel sheets 10 cm apart) constituted the exterior of the side and bottom. As a cold liquid at temperature of -23 C was poured inside the gap of the double wall and circulated, the soil around the tank began to freeze sideways and downwards from the tank. Studies made are as follows: (1) the progress of the freezing front was measured and preestimated; (2) frost heaving characters of the tank and the ground surface around it were observed; (3) soil water migration was calculated by measuring moisture tensions at several points within the soil; (4) soil pressure acting on the tank was measured.

Kinosita, S.; Fukuda, M.; Ishizaki, T.; Yamamoto, H.

297

Freezing of polar stratospheric clouds in orographically induced strong warming events  

NASA Astrophysics Data System (ADS)

Results from laboratory experiments and microphysical modeling are presented that suggest a potential freezing nucleation mechanism for polar stratospheric cloud (PSC) particles above the water ice frost point (Tice). The mechanism requires very high HNO3 concentrations of about 58 wt% in the droplets, and leads to the freezing of nitric acid dihydrate (NAD) in a highly selective manner in the smallest droplets of an ensemble. In the stratosphere such liquid compositions are predicted to occur in aerosol droplets which are warmed adiabatically with rates of about +150 K/h from below 190 K to 194 K. Such rapid temperature changes have been observed in mountain leewaves that occur frequently in the stratosphere, clearly demonstrating the need for a stratospheric gravity wave climatology.

Tsias, A.; Prenni, A. J.; Carslaw, K. S.; Onasch, T. P.; Luo, B. P.; Tolbert, M. A.; Peter, Th.

1997-09-01

298

Did Water Leave Its Mark on Mars?  

ERIC Educational Resources Information Center

Discusses the missing water on Mars. Describes five experiments simulating conditions on Mars: (1) behavior of dry ice; (2) low-pressure vacuum; (3) freezing point depression; (4) water in hydrated minerals and clay; and (5) properties of carbon dioxide. (YP)

Secosky, James J.

1989-01-01

299

Freeze-Tolerant Condensers  

NASA Technical Reports Server (NTRS)

Two condensers designed for use in dissipating heat carried by working fluids feature two-phase, self-adjusting configurations such that their working lengths automatically vary to suit their input power levels and/or heat-sink temperatures. A key advantage of these condensers is that they can function even if the temperatures of their heat sinks fall below the freezing temperatures of their working fluids and the fluids freeze. The condensers can even be restarted from the frozen condition. The top part of the figure depicts the layout of the first condenser. A two-phase (liquid and vapor) condenser/vapor tube is thermally connected to a heat sink typically, a radiatively or convectively cooled metal panel. A single-phase (liquid) condensate-return tube (return artery) is also thermally connected to the heat sink. At intervals along their lengths, the condenser/vapor tube and the return artery are interconnected through porous plugs. This condenser configuration affords tolerance of freezing, variable effective thermal conductance (such that the return temperature remains nearly constant, independently of the ultimate sink temperature), and overall pressure drop smaller than it would be without the porous interconnections. An additional benefit of this configuration is that the condenser can be made to recover from the completely frozen condition either without using heaters, or else with the help of heaters much smaller than would otherwise be needed. The second condenser affords the same advantages and is based on a similar principle, but it has a different configuration that affords improved flow of working fluid, simplified construction, reduced weight, and faster recovery from a frozen condition.

Crowley, Christopher J.; Elkouhk, Nabil

2004-01-01

300

Ice/Water Interface: Zeta Potential, Point of Zero Charge, and Hydrophobicity.  

PubMed

The ice/water interface is a common and important part of many biological, environmental, and technological systems. In contrast to its importance, the system has not been extensively studied and is not well understood. Therefore, in this paper the properties of the H(2)O ice/water and D(2)O ice/water interfaces were investigated. Although the zeta potential vs pH data points were significantly scattered, it was determined that the isoelectric point (iep) of D(2)O ice particles in water at 3.5 degrees C containing 10(-3) M NaCl occurs at about pH 3.0. The negative values of the zeta potential, calculated from the electrophoretic mobility, seem to decrease with decreasing content of NaCl, while the iep shifts to a higher pH. The point of zero charge (pzc) of D(2)O ice and H(2)O ice, determined by changes in pH of 10(-4) M NaCl aqueous solution at 0.5 degrees C after the ice particle addition, was found to be very different from the iep and equal to pH 7.0 +/- 0.5. The shift of the iep with NaCl concentration and the difference in the positions of the iep and pzc on the pH scale point to complex specific adsorption of ions at the interface. Interestingly, similar values of iep and pzc were found for very different systems, such as hydrophilic ice and highly hydrophobic hexadecane droplets in water. A comparison of the zeta potential vs pH curves for hydrophilic ice and hydrophobic materials that do not possess dissociative functional groups at the interface (diamond, air bubbles, bacteria, and hexadecane) indicated that all of them have an iep near pH 3.5. These results indicate that the zeta potential and surface charge data alone cannot be used to delineate the electrochemical properties of a given water/moiety interface because similar electrical properties do not necessary mean a similar structure of the interfacial region. A good example is the aliphatic hydrocarbon/water interface in comparison to the ice/water interface. Although the experiments were carried out with care, both the zeta potential, measured with a precise ZetaPlus meter, and DeltapH values (a measure of surface charge) vs pH were significantly scattered, and the origin of dissemination of the data points was not established. Differently charged ice particles and not fully equilibrium conditions at the ice/water interface may have been responsible for the dissemination of the data. Copyright 1999 Academic Press. PMID:10607438

Drzymala; Sadowski; Holysz; Chibowski

1999-12-15

301

Petroleum refinery secondary effluent polishing using freezing processes--toxicity and organic contaminant removal.  

PubMed

A petroleum refinery secondary effluent was treated using two freezing techniques--spray freezing and unidirectional downward freezing (UDF). The freezing processes were effective to remove toxicity and total organic carbon (TOC)- and chemical oxygen demand (COD)-causing materials in the effluent. Agitation of the liquid during UDF significantly improved the impurity separation efficiency; 85 to 96% removal of TOC and COD was achieved without any pretreatment and freezing only 70% of the feed water. The treatment efficiency of the spray freezing was at the same level as that of UDF without mixing. The spray ice with longer storage time released more contaminants with early meltwater. The initial contaminant concentration of the feed water and the freezing temperatures (-10 degrees C and -25 degrees C) had no significant influence on the treatment efficiency. A small fluctuation in effluent TOC concentration caused a dramatic change in effluent toxicity (Microtox). The effective concentration (EC20) (Microtox) was effective in detecting effluent toxicity. PMID:18686927

Gao, W; Smith, D W; Habib, M

2008-06-01

302

On the Freezing and Melting Behavior of the Eutectic Pt-C  

NASA Astrophysics Data System (ADS)

The feasibility of referring to freezing as an alternative to melting for defining the eutectic transition temperature has been studied using two Pt-C cells constructed at NIM, one of a sleeve type, and the other of a hybrid type, including support. Freezing and melting experiments have been done by varying the offset of the furnace temperature T furn with respect to the nominal eutectic temperature T E used to freeze the fixed point with offsets ( T furn- T E)freeze from -5 K to -40 K, followed by melting at a fixed offset ( T furn- T E)melt = + 20 K. Plotting the liquidus temperatures T liq,freeze and T liq,melt obtained for freezing and melting against {(T_E-T_furn)^{1/2}_freeze} resulted in linear relations for both cells, allowing extrapolation toward T liq,freeze(0) and T liq, melt(0). For the cells Pt-C5# and Pt-C6# under study: T liq,melt(0)- T liq,freeze(0) = 10 mK and 20 mK, respectively, with a standard uncertainty of 30 mK for both T liq,melt(0) and T liq,freeze(0). The coherence of the results obtained for melting and freezing indicates that freezing can be used, as an alternative to melting, to define the liquidus temperature T liq(0) of the eutectic Pt-C.

Dong, W.; Bloembergen, P.; Wang, T.; Duan, Y. Y.

2011-12-01

303

Freezing of Nonwoody Plant Tissue  

PubMed Central

Temperature recordings of the freezing of plant tissues include two plateaus or regions of reduced slope. During the second of these, small positive spikes were observed. When a completely frozen tissue was thawed and refrozen, neither the second plateau nor the spikes were recorded. Both were present, however, if the initial freezing had been terminated before the second plateau had been reached. The spikes appear to represent the release of heat of crystallization during the freezing of individual cells. Such a freezing and thawing cycle destroys the ability of the cells to remain supercooled in the presence of the ice that is formed as the first plateau is recorded.

Brown, M. S.; Pereira, E. Sa B.; Finkle, Bernard J.

1974-01-01

304

Characterization of the TIP4P-Ew water model: Vapor pressure and boiling point  

NASA Astrophysics Data System (ADS)

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.

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

2005-11-01

305

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

PubMed

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

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

2005-11-15

306

Sustainable colloidal-silver-impregnated ceramic filter for point-of-use water treatment.  

PubMed

Cylindrical colloidal-silver-impregnated ceramic filters for household (point-of-use) water treatment were manufactured and tested for performance in the laboratory with respect to flow rate and bacteria transport. Filters were manufactured by combining clay-rich soil with water, grog (previously fired clay), and flour, pressing them into cylinders, and firing them at 900 degrees C for 8 h. The pore-size distribution of the resulting ceramic filters was quantified by mercury porosimetry. Colloidal silver was applied to filters in different quantities and ways (dipping and painting). Filters were also tested without any colloidal-silver application. Hydraulic conductivity of the filters was quantified using changing-head permeability tests. [3H]H2O water was used as a conservative tracer to quantify advection velocities and the coefficient of hydrodynamic dispersion. Escherichia coli (E. coli) was used to quantify bacterial transport through the filters. Hydraulic conductivity and pore-size distribution varied with filter composition; hydraulic conductivities were on the order of 10(-5) cm/s and more than 50% of the pores for each filter had diameters ranging from 0.02 to 15 microm. The filters removed between 97.8% and 100% of the applied bacteria; colloidal-silver treatments improved filter performance, presumably by deactivation of bacteria. The quantity of colloidal silver applied per filter was more important to bacteria removal than the method of application. Silver concentrations in effluent filter water were initially greater than 0.1 mg/L, but dropped below this value after 200 min of continuous operation. These results indicate that colloidal-silver-impregnated ceramic filters, which can be made using primarily local materials and labor, show promise as an effective and sustainable point-of-use water treatment technology for the world's poorest communities. PMID:18323124

Oyanedel-Craver, Vinka A; Smith, James A

2008-02-01

307

Anchoring the water dimer potential energy surface with explicitly correlated computations and focal point analyses  

NASA Astrophysics Data System (ADS)

Ten stationary points on the water dimer potential energy surface have been characterized with the coupled-cluster technique which includes all single and double excitations as well as a perturbative approximation of triple excitations [CCSD(T)]. Using a triple-? basis set with two sets of polarization functions augmented with higher angular momentum and diffuse functions [TZ2P(f,d)+dif], the fully optimized geometries and harmonic vibrational frequencies of these ten stationary points were determined at the CCSD(T) theoretical level. In agreement with other ab initio investigations, only one of these ten stationary points is a true minimum. Of the other nine structures, three are transition structures, and the remaining are higher order saddle points. These high-level ab initio results indicate that the lowest lying transition state involved in hydrogen interchange is chiral, of C1 symmetry rather than Cs as suggested by recently developed 6D potential energy surfaces. The one- and n-particle limits of the electronic energies of these ten stationary points were probed by systematic variation of the atomic orbital basis sets and the treatment of electron correlation within the framework of the focal-point analysis of Allen and co-workers. The one-particle limit was approached via extrapolation of electronic energies computed with the augmented correlation consistent basis sets (aug-cc-pVXZ, X=D-6), and, independently, by estimating the basis set incompleteness effect with the explicitly-correlated second-order Møller-Plesset method (MP2-R12). Electron correlation was evaluated at levels as high as the Brueckner coupled cluster method with double excitations and perturbatively treated triple and quadruple excitations [BD(TQ)]. Core correlation and relativistic effects were also assessed. Consideration of the aforementioned electronic effects as well as basis set superposition error leads to an estimate of 21.0 kJ mol-1 for the electronic dissociation energy of (H2O)2.

Tschumper, Gregory S.; Leininger, Matthew L.; Hoffman, Brian C.; Valeev, Edward F.; Schaefer, Henry F.; Quack, Martin

2002-01-01

308

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

NASA Astrophysics Data System (ADS)

Water triple point cells are essential for realization of the International Temperature Scale of 1990 (ITS-90). There is some evidence that achieving the ultimate performance of water triple point cells may be restricted by the variation in the position of the platinum resistance thermometer at the bottom of the re-entrant well, and that the variation in position is not completely compensated for by correction to zero measurement sensing current. This comparative study focused on the use of quartz bushes (tubular sleeves around the thermometer) of two different lengths, to improve the thermal contact and to help locate the thermometer. It shows that an improvement in repeatability of the resistance readings was achieved. The experiments were conducted over a five-week period using a standard platinum resistance thermometer, a one water cell, and two different lengths of quartz bushes. The resistance measurements were performed using an Automatic Systems Laboratories F900 resistance bridge. A description of the experiment and results is given. Significant improvement in the repeatability of the measurement of resistance was observed (factor >2) when quartz bushes were used.

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

2010-09-01

309

Studies on Freezing RAM Semen in Absence of Glycerol.  

NASA Astrophysics Data System (ADS)

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.

Abdelnaby, Abdelhady Abdelhakeam

1988-12-01

310

Performance Characteristics of an Isothermal Freeze Valve  

SciTech Connect

This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

Hailey, A.E.

2001-08-22

311

Utilization of polysaccharide coatings to improve freeze–thaw and freeze–dry stability of protein-coated lipid droplets  

Microsoft Academic Search

The impact of freezing–thawing and freeze–drying on the physical stability of oil-in-water (O\\/W) emulsions containing protein-coated and protein\\/polysaccharide-coated droplets has been studied. O\\/W emulsions (2wt% corn oil, 0.12wt% ?-lactoglobulin, pH 3.5) were prepared that contained either 0 or 0.2wt% pectin or ?-carrageenan, and 0–8wt% maltodextrin. The emulsions were then subjected to either freeze–thaw cycling (?20°C, 22h; +30°C, 2h; ×2) or

Saehun Mun; Younghee Cho; Eric Andrew Decker; David Julian McClements

2008-01-01

312

Viability of spores after repeate freezing and thawing shocks  

Microsoft Academic Search

Survival of spores of the fungusRhizopus nigricans after repeated freezing and thawing was investigated. The cooling rate was 104°C\\/min. Dry spores were fully inactive after 32 repeated shocks. About one-half of spores were killed after 8 repetitions.\\u000a The water content did not change the resistance, swollen spores reacted to shocks much like dry ones. The sensitivity of spores\\u000a to freezing-thawing

O. Ne?as; M. Gabriel

1978-01-01

313

Study of the Magnetic Field Effect on Commercial Thermistors using a Water Triple Point  

NASA Astrophysics Data System (ADS)

The effect of a magnetic field on commercial thermistors was precisely studied in detail using the water triple point. A thermistor with a code of 44004 manufactured by YSI Inc. was found to show a small correction. Its orientation effect and sensor dependence was found also to be small. The correction ? T (mK) against magnetic field B(T) was found to be 0.069(B/T)2 (mK). The uncertainty of the correction function is estimated to be as small as 2 mK up to 15 T.

Nara, Koichi

2005-03-01

314

Effects of different Methods of Preparation of Ice Mantles of Triple Point of Water Cells on the Temporal Behaviour of the Triple-Point Temperatures.  

National Technical Information Service (NTIS)

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: (1) solid carbon dioxide, (2) an immersion cooler, (3) liqu...

B. W. Mangum G. F. Strouse G. T. Furukawa

2008-01-01

315

Atmospheric Pressure Glow Discharge for Point-of-Use Water Treatment  

NASA Astrophysics Data System (ADS)

Treatment of biological and chemical contaminants is an area of growing global interest where atmospheric pressure plasmas can make a significant contribution. Addressing key challenges of volume processing and operational cost, a large volume 162 MHz coaxial air-plasma source has been developed.footnotetextByrns (2012) J. Phys. D: Appl. Phys. 45 (2012) 195204 Because of VHF ballasting effects, the electric discharge is maintained at a steady glow, allowing formation of critical non-equilibrium chemistry. High densities, ne = 10^11-10^12, have been recorded. The atmospheric nature of the device permits straightforward and efficient treatment of water samples. [H^+] concentrations in 150 milliliter tap water samples have been shown to increase by 10^5 after five minutes of discharge exposure. Recent literature has demonstrated that increasing acidity is strongly correlated with a solution's ability to deactivate microbial contaminants.footnotetextTraylor (2011) J. Phys. D: Appl. Phys. 44 (2011) 472001 The work presented here will explore the impact of treatment gas, system configuration, and power density on water disinfection and PFC abatement. An array of plasma diagnostics, including OES and electrical measurements, are combined with post-process water analysis, including GC-MS and QT analysis of coliform and E.coli bacteria. Development of volume processing atmospheric plasma disinfection methods offers promise for point-of-use treatments in developing areas of the world, potentially supplementing or replacing supply and weather-dependent disinfection methods.

Lindsay, Alexander; Byrns, Brandon; Shannon, Steven; Knappe, Detlef

2012-10-01

316

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

PubMed

The particle removal performance of point-of-use ceramic water filters (CWFs) was characterized in the size range of 0.02-100 microm 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 microm spheres were highly variable between the six filters, ranging from 63 to 99.6%. For the 0.5 microm spheres removal was less variable and in the range of 95.1-99.6%, while for the 1, 2, 4.5, and 10 microm spheres removal was >99.6%. Recoating four of the CWFs with colloidal silver solution improved removal of the 0.02 microm spheres, but had no significant effects on the other particle sizes. Log removals of 1.8-3.2 were found for natural turbidity and spiked kaolin clay particles; however, particles as large as 95 microm were detected in filtered water. PMID:19926110

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

2010-03-01

317

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

NASA Astrophysics Data System (ADS)

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 TPW cells are described. Supercooled water in small TPW cells spontaneously transformed into uniform metastable dendritic crystals throughout the cells at supercoolings ranging from 5.85 °C to 8.77 °C and then changed into stable hexagonal closed-packed cellular crystals, forming an outer ice mantle from the outside inward. Some pertinent explanations based on thermodynamic solidification theory were used to describe the phase transition process in the mush method. In addition, the experimental results indicated that the realized temperatures of water in the small TPW cells were in good agreement within 0.1 mK approximately 6 h after the initial spontaneous crystallization had occurred. Finally, the small TPW cells (s/n 008 and s/n 001) were directly compared with a conventional TPW cell (s/n NIM-1-211); the temperature differences between the small TPW cells and the regular TPW cell were less than 0.21 mK.

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

2011-01-01

318

A novel approach for designing simple point charge models for liquid water with three interaction sites.  

PubMed

A simultaneous improvement of the diffusion and dielectric properties of the simple point charge (SPC) model for liquid water appears to be very difficult with conventional reparametrization of the commonly used Lennard-Jones and Coulomb interaction functions and without including a self-energy correction in the effective pair-potential as is done in the SPC/E model. Here, a different approach to circumvent this problem is presented. A short-range interaction term, which corrects the oxygen-oxygen energy at small distances by small amounts of energy, was introduced in the nonbonded interaction function. This additional force-field term allows to derive new parameter sets for SPC-like water models that yield better agreement with experimental data on liquid water. Based on previous investigations of the force-field parameter dependence of the water properties of SPC-like models, the necessary parameter changes to obtain a lower diffusion coefficient and a larger dielectric permittivity were specified and accordingly six new models were developed. They all represent an improvement over SPC in terms of structural and diffusional properties, four of them show better dielectric properties also. One model, SPC/S, has been characterized in more detail, and represents most properties of liquid water better than SPC while avoiding the larger discrepancies with experimental values regarding density, thermal compressibility, energy, and free energy of the SPC/E model. We conclude that the use of a simple, short-ranged additional oxygen-oxygen interaction term makes a simultaneous improvement of the diffusion coefficient and the dielectric properties of water feasible. PMID:12759908

Glättli, Alice; Daura, Xavier; Van Gunsteren, Wilfred F

2003-07-15

319

Development of Freeze Dried Vegetables.  

National Technical Information Service (NTIS)

The development of freeze dried vegetables to be used in the Apollo food system is discussed. After the initial selection and screening of vegetables, several types of freeze dried vegetables were prepared in small batches. From these small batches, two v...

R. W. Larson

1970-01-01

320

Encapsulation and sustained release from biodegradable microcapsules made by emulsification\\/freeze drying and spray\\/freeze drying  

Microsoft Academic Search

Hollow biodegradable poly(dl-lactide) (PLA) particles with porous shell walls were prepared by freeze drying small droplets of PLA solution formed by emulsification or spraying. The hollow freeze-dried particles were dispersed in water, and the resulting aqueous suspensions were exposed to plasticizing solvents, either dichloromethane or compressed carbon dioxide. The plasticizing solvent causes the pores in the shell wall to close,

Weisi Yin; M. Z. Yates

2009-01-01

321

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

NASA Astrophysics Data System (ADS)

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 with increasing age of the cells, which is called long-term drift. To investigate this mystery, we used cells with different manufacture dates ranging from 1974 to 2002 and compared their analyses, which were done in 1984 and 2003. Using the same model of long-term drift as that used by Hill, the long-term drift rates of the two data sets are 4.7 ?K·year-1 and 9.2 ?K·year-1, respectively. One is consistent with the observed depression of about 4 ?K·year-1 measured by Hill, whereas the other differs greatly from Hill’s result. In addition, corresponding factors influencing long-term drift are discussed in this paper.

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

2008-06-01

322

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

PubMed

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

Chatterley, Christie; Linden, Karl

2010-09-01

323

Assessment of a low-cost, point-of-use, ultraviolet water disinfection technology.  

PubMed

We describe a point-of-use (POU) ultraviolet (UV) disinfection technology, the UV Tube, which can be made with locally available resources around the world for under $50 US. Laboratory and field studies were conducted to characterize the UV Tube's performance when treating a flowrate of 5 L/min. Based on biological assays with MS2 coliphage, the UV Tube delivered an average fluence of 900+/-80 J/m(2) (95% CI) in water with an absorption coefficient of 0.01 cm(-1). The residence time distribution in the UV Tube was characterized as plug flow with dispersion (Peclet Number = 19.7) and a mean hydraulic residence time of 36 s. Undesirable compounds were leached or produced from UV Tubes constructed with unlined ABS, PVC, or a galvanized steel liner. Lining the PVC pipe with stainless steel, however, prevented production of regulated halogenated organics. A small field study in two rural communities in Baja California Sur demonstrated that the UV Tube reduced E. coli concentrations to less than 1/100 ml in 65 out of 70 samples. Based on these results, we conclude that the UV Tube is a promising technology for treating household drinking water at the point of use. PMID:17998607

Brownell, Sarah A; Chakrabarti, Alicia R; Kaser, Forest M; Connelly, Lloyd G; Peletz, Rachel L; Reygadas, Fermin; Lang, Micah J; Kammen, Daniel M; Nelson, Kara L

2008-03-01

324

Point-Nonpoint Source Water Quality Trading: A Case Study in the Minnesota River Basin  

NASA Astrophysics Data System (ADS)

Contrary to the general trend of only a few actual trades occurring within point-nonpoint source water quality trading programs in the United States, two trading projects in the Minnesota River Basin, created under the provisions of National Pollutant Discharge Elimination System (NPDES) permits, have generated five major trades and numerous smaller ones. In this paper, these two projects are described to illustrate their origins, implementation, and results. It was found that several factors contributed to the relatively high number of trades in these projects, including the offsetting nature of the projects (hence a fixed number of credits that the point sources were required to obtain), readily available information on potential nonpoint source trading partners, and an effectively internal trading scheme used by one of the two projects. It was also found that long term structural pollution control measures, such as streambank stabilization, offered substantial cost savings over point source controls. Estimates of transaction costs showed that the total costs of the trading projects were increased by at least 35 percent after transaction costs were taken into account. Evidence also showed that in addition to pollution reduction, these two trading projects brought other benefits to the watershed, such as helping balance environmental protection and regional economic growth.

Fang, Feng; Wiliam Easter, K.; Brezonik, Patrick L.

2005-06-01

325

Energy and water conservation in frozen vs. supercooled larvae of the goldenrod gall fly, Eurosta solidaginis (fitch) (Diptera: Tephritidae).  

PubMed

Insects that tolerate severe cold during winter may either supercool or tolerate ice forming within the tissues of the body. To compare the relative advantages of freezing and supercooling, we measured rates of CO(2) production and water loss in frozen and supercooled goldenrod gall fly larvae (Eurosta solidaginis). As an important first step, we measured the time required for ice content and metabolic rate to stabilize upon freezing. Ice content stabilized after only three hours of freezing at -5 degrees C, whereas CO(2) production required 12 hours to stabilize. Subsequent experiments found that freezing greatly reduced both water loss and metabolic rate. Comparisons of supercooled and frozen larvae at -5 degrees C indicated that CO(2) production fell 47% with freezing and water loss decreased 35%. As temperature decreased to -10 and -15 degrees C, CO(2) production fell exponentially and was no longer detectable at -20 degrees C with our measurement system. Our results demonstrate that freezing significantly reduces energy consumption during the winter and may therefore improve winter survival and spring fecundity. The advantages of freezing over supercooling would drive selection toward insect freeze tolerance and also toward higher supercooling points to increase the duration of freezing each winter. PMID:11857468

Irwin, Jason T; Lee, Richard E

2002-03-01

326

Assessment of the Moving Point Method for Numerical Calculation of Fluid-Structure Interaction in Water Hammer.  

National Technical Information Service (NTIS)

The problem of providing an accurate numerical method for modelling fluid-structure interaction in practical water hammer calculations for power station pipe networks is addressed. The application of the moving point method to a problem representative of ...

N. A. Edwards C. P. Please

1988-01-01

327

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

NASA Astrophysics Data System (ADS)

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 (2-4 log units of cfu/100 ml) and risk levels were grossly in excess of acceptable health risk (AHR) levels for bathing and drinking. PHR was 2-3 times higher with the Cabelli (IE) model (Equation (2)) compared to the US EPA (EC) model (Equation (1)). Risk levels varied among WAPs in concomitance to the spatial and seasonal variability of ambient EC and IE densities. With the Cabelli IE model, PHR of HCGI illness on single exposure to the dry weather 95th percentile IE density for bathing was 2.5% of the exposed population at Logoman compared to 5.2% at Turkana Flats, 4.9% at Kenyatta or Nessuit and 4.6%, 4.5% and 4.2% at Treetop, Segotik and Njoro Bridge, respectively. PHR was ?5% on exposure to the wet weather 95th percentile IE density at all WAPs, excepting Treetop with 4.3%. Relative risk levels increased by at least 30 and 70 times for GI and HCGI illnesses, respectively, from drinking (250 ml) raw stream water, rising erratically in wet weather by >80% of the dry weather risk at Logoman, >30% at Njoro Bridge and Kenyatta and 10-15% at Segotik, Nessuit and Turkana Flats. By stipulating freshwater bathing water quality guidelines of 126 and 33 cfu/100 ml for EC and IE, respectively, US, EPA upholds maximum AHR levels at 0.7% and 1.9% for EC and IE, respectively. Hence, reducing current PHR levels at the WAPs to the US, EPA bathing AHR levels would require at least 2-4 log reductions of IE and EC densities with even further log reductions to achieve the WHO recommended drinking water AHR level of 0.1%. This would necessitate specialized treatment, in particular point-of-use treatment at the household level, as well as the implementation of comprehensive catchment management measures to protect the stream and the WAPs.

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

328

Dew points of ternary methane+ethane+butane and quaternary methane+ethane+butane+water mixtures: measurement and correlation  

Microsoft Academic Search

Dew points for ternary methane+ethane+butane and quaternary methane+ethane+butane+water mixtures were determined experimentally between 4.77×105 and 99.45×105 Pa and at temperatures from 250.92 to 288.54 K. The experimental dew point curves of the mixtures with water were reproduced quite accurately with an excess function–equation of state method, independent of the temperature and pressure ranges.

Sof??a T Blanco; Susana Avila; Inmaculada Velasco; Evelyne Rauzy; Santos Ot??n

2000-01-01

329

Freezing of Barley Studied by Infrared Video Thermography1  

PubMed Central

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°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.

Pearce, Roger S.; Fuller, Michael P.

2001-01-01

330

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

Microsoft Academic Search

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

H. Vömel; D. E. David; K. Smith

2007-01-01

331

Freeze Tolerant Radiator for an Advanced EMU  

NASA Technical Reports Server (NTRS)

During an Extravehicular Activity (EVA), the astronaut s metabolic heat and the heat produced by the Portable Life Support Unit (PLSS) must be rejected. This heat load is currently rejected by a sublimator, which vents up to eight pounds of water each EVA. However, for advanced space missions of the future, water venting to space needs to be minimized because resupply impacts from earth will be prohibitive. If this heat load could be radiated to space from the PLSS, which has enough surface area to radiate most of the heat, the amount of water now vented could be greatly reduced. Unfortunately, a radiator rejects heat at a relatively constant rate, but the astronauts generate a variable heat load depending on how hard they are working. Without a way to vary the heat removal rate, the astronaut would experience cold discomfort or even frostbite. A proven method allowing a radiator to be turned-down is to sequentially allow tubes that carry the heat transfer fluid to the radiator to freeze. A drawback of current freezable radiators using this method is that they are far to heavy for use on a PLSS, because they use heavy construction to prevent the tubes from bursting as they freeze and thaw. This creates the need for a large radiator to reject most of the heat but with a lightweight tube that doesn t burst as it freezes and thaws. The new freezable radiator for the Extravehicular Mobility Unit (EMU) has features to accommodate the expansion of the radiator fluid when it freezes, and still have the high tube to fin conductance needed to minimize the number and weight of the tubes. Radiator fluid candidates are water and a propylene glycol-water mixture. This design maintains all materials within their elastic limits so that large volume changes can be achieved without breaking the tube. This concept couples this elastic expansion with an extremely lightweight, extremely high conductivity carbon fiber fin that can carry the heat needed to thaw a frozen tube. By using most of the exposed surface area of the PLSS as a radiator, the system can reject about 75% of the highest heat load, and reduce the loss of water through sublimation by a factor of four. The proposed radiator and a small water tank can be no heavier than the current system.

Copeland, Robert J.; Elliott, Jeannine; Weislogel, Mark

2004-01-01

332

A NEW FREEZING-ULTRAMICROTOME  

PubMed Central

The difficulties in sectioning frozen biological objects for electron microscopic investigations are overcome by Steere's freezing-etching method. In order to test this method and to open up a wide field of application, the new freezing-ultramicrotome has been designed. The apparatus consists of the combination of an ultramicrotome with freezing-drying and shadow-casting installations in the same vacuum container. The preliminary results show, on the one hand, the practicability of all preparational steps and, on the other, that it is possible to resolve internal structures of cell organelles and even macromolecular patterns.

Moor, H.; Muhlethaler, K.; Waldner, H.; Frey-Wyssling, A.

1961-01-01

333

Biomimetic Materials by Freeze Casting  

NASA Astrophysics Data System (ADS)

Natural materials, such as bone and abalone nacre, exhibit exceptional mechanical properties, a product of their intricate microstructural organization. Freeze casting is a relatively simple, inexpensive, and adaptable materials processing method to form porous ceramic scaffolds with controllable microstructural features. After infiltration of a second polymeric phase, hybrid ceramic-polymer composites can be fabricated that closely resemble the architecture and mechanical performance of natural bone and nacre. Inspired by the narwhal tusk, magnetic fields applied during freeze casting can be used to further control architectural alignment, resulting in freeze-cast materials with enhanced mechanical properties.

Porter, Michael M.; Mckittrick, Joanna; Meyers, Marc A.

2013-06-01

334

Evolution of freezing susceptibility and freezing tolerance in terrestrial arthropods  

Microsoft Academic Search

Abstract – Arthropods have evolved,various adaptations to survive adverse seasons and it has long been discussed why some arthropods are freezing-susceptible and some are freezing-tolerant. However, which mode of frost resistance came,first during the course of evolution? A commonly,held opinion is that no choice of strategy has been offered in evolution, because each species of arthropod may have its own

Ecology Écologie; Philippe Vernon; Guy Vannier

335

Cloud point extraction, preconcentration and simultaneous spectrophotometric determination of nickel and cobalt in water samples  

NASA Astrophysics Data System (ADS)

Cloud point extraction has been used for the preconcentration and simultaneous spectrophotometric determination of nickel and cobalt after the formation of a complex with 2-amino-cyclopentene-1-dithiocarboxylic acid (ACDA), and latter analysis by spectrophotometer using Triton X-114 as surfactant. The parameters affecting the separation phase and detection process were optimized. Under the optimum experimental conditions (i.e. pH=5, 0.07 mM ACDA, Triton X-114 = 0.25% (w/v)), calibration graphs were linear in the range of 20-500 and 20-200 ?g l -1 with detection limits of 10 and 7.5 ?g l -1 for Ni and Co, respectively. The method was applied to the determination of Ni and Co in natural and waste water samples with satisfactory results.

Safavi, A.; Abdollahi, H.; Hormozi Nezhad, M. R.; Kamali, R.

2004-10-01

336

What is 'unfreezable water', how unfreezable is it, and how much is there?  

PubMed

Water that remains unfrozen at temperatures below the equilibrium bulk freezing temperature, in the presence of ice, is sometimes called unfreezable or bound. This paper analyses the phenomenon in terms of quantitative measurements of the hydration interaction among membranes or macromolecules at freezing temperatures. These results are related to analogous measurements in which osmotic stress or mechanical compression is used to equilibrate water of hydration with a bulk phase. The analysis provides formulas to estimate, at a given sub-freezing temperature, the amount of unfrozen water due to equilibrium hydration effects. Even at tens of degrees below freezing, this hydration effect alone can explain an unfrozen water volume that considerably exceeds that of a single 'hydration shell' surrounding the hydrophilic surfaces. The formulas provided give a lower bound to the amount of unfrozen water for two reasons. First, the well-known freezing point depression due to small solutes is, to zeroth order, independent of the membrane or macromolecular hydration effect. Further, the unfrozen solution found between membranes or macromolecules at freezing temperatures has high viscosity and small dimensions. This means that dehydration of such systems, especially at freezing temperatures, takes so long that equilibrium is rarely achieved over normal experimental time scales. So, in many cases, the amount of unfrozen water exceeds that expected at equilibrium, which in turn usually exceeds that calculated for a single hydration shell. PMID:12148018

Wolfe, Joe; Bryant, Gary; Koster, Karen L

2002-01-01

337

Assimilating point snow water equivalent data into a distributed snow cover model  

NASA Astrophysics Data System (ADS)

In Switzerland, snow melt dominates the runoff in many watersheds and the total snow storage contributing to discharge can vary largely from year to year. Accurately quantifying snow storage and subsequent runoff is important for regulating lake levels throughout the country. Additionally, melting snow can contribute to floods imposing large damages on infrastructure. To better quantify the snow storage, we examine whether the performance of a distributed snow model improves when applying different methods for assimilating point snow water equivalent (SWE) data. We update the model results by using either the ensemble Kalman filter or a combination of the ensemble Kalman filter and statistical interpolation. The filter performance was assessed by comparing the simulation results against observed SWE and snow covered fraction. We show that a method which assimilates daily changes in SWE performs better than an approach for updating the model using the SWE data directly. Both assimilation methods showed higher model performance than a control simulation not utilizing data assimilation. Both filter simulations also showed better agreements with the SWE observations than an interpolation method optimized for snow data. The results show that the three-dimensional data assimilation methods were useful for transferring the information in the point snow observations across the domain simulated by the distributed snow model.

Magnusson, Jan; Gustafsson, David; Hüsler, Fabia; Jonas, Tobias

2014-05-01

338

The Discontinuity in the First Derivative of the ITS-90 at the Triple Point of Water  

NASA Astrophysics Data System (ADS)

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 for `less ideal' SPRTs (those with lower temperature coefficients of resistance), and also for sub-ranges not extending beyond the indium point. These results are investigated vis-à-vis the long-standing observation that the ITS-90 reference values W r(Ga) and W r(Hg) are not completely consistent with data for W(Ga) and W(Hg) for real SPRTs. It discusses what may be done in a future scale to ensure continuity in the first derivative, and it concludes with a comment about the acceptance criteria for SPRTs in the scale.

Rusby, R. L.

2010-09-01

339

Source to point of use drinking water changes and knowledge, attitude and practices in Katsina State, Northern Nigeria  

Microsoft Academic Search

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

B. Onabolu; O. D. Jimoh; S. B. Igboro; M. K. C. Sridhar; G. Onyilo; A. Gege; R. Ilya

2011-01-01

340

Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view  

SciTech Connect

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.

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

341

Instantaneous normal mode analysis for intermolecular and intramolecular vibrations of water from atomic point of view.  

PubMed

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. PMID:24289362

Chen, Yu-Chun; Tang, Ping-Han; Wu, Ten-Ming

2013-11-28

342

Measuring Total Column Water Vapor by Pointing an Infrared Thermometer at the Sky  

NASA Technical Reports Server (NTRS)

A 2-year study affirms that the temperature (Tz) indicated by an inexpensive ($20 to $60) IR thermometer pointed at the cloud-free zenith sky provides an approximate indication of the total column water vapor (precipitable water or PW). PW was measured by a MICROTOPS II sun photometer. The coefficient of correlation (r2) of the PW and Tz was 0.90, and the rms difference was 3.2 mm. A comparison of the Tz data with the PW provided by a GPS site 31 km NNE yielded an r2 of 0.79, and an rms difference of 5.8 mm. An expanded study compared Tz from eight IR thermometers with PW at various times during the day and night from 17 May to 18 October 2010, mainly at the Texas site and 10 days at Hawaii's Mauna Loa Observatory (MLO). The best results of this comparison were provided by two IR thermometers models that yielded an r2 of 0.96 and an rms difference with the PW of 2.7 mm. The results of both the ongoing 2-year study and the 5-month instrument comparison show that IR thermometers can measure PW with an accuracy (rms difference/mean PW) approaching 10%, the accuracy typically ascribed to sun photometers.

Mims, Forrest M., III; Chambers, Lin H.; Brooks, David R.

2011-01-01

343

An Experimental Investigation of the Long-Term Stability of Triple-Point-of-Water Cells  

NASA Astrophysics Data System (ADS)

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 -6 \\upmu K {\\cdot } year^{-1} ({± }2 \\upmu K {\\cdot } year^{-1}) , in reasonable agreement with an average drift of -4 \\upmu K {\\cdot } year^{-1} suggested 12 years ago. It was concluded that fused quartz is the superior container for TPW cells.

Hill, K. D.

2014-06-01

344

Risk-based prioritization of ground water threatening point sources at catchment and regional scales.  

PubMed

Contaminated sites threaten ground water resources all over the world. The available resources for investigation and remediation are limited compared to the scope of the problem, so prioritization is crucial to ensure that resources are allocated to the sites posing the greatest risk. A flexible framework has been developed to enable a systematic and transparent risk assessment and prioritization of contaminant point sources, considering the local, catchment, or regional scales (Danish EPA, 2011, 2012). The framework has been tested in several catchments in Denmark with different challenges and needs, and two of these are presented. Based on the lessons learned, the Danish EPA has prepared a handbook to guide the user through the steps in a risk-based prioritization (Danish EPA, 2012). It provides guidance on prioritization both in an administratively defined area such as a Danish Region, and within the bounds of a specified ground water catchment. The handbook presents several approaches in order to prevent the prioritization from foundering because of a lack of data or an inappropriate level of complexity. The developed prioritization tools, possible graphical presentation and use of the results are presented using the case studies as examples. The methodology was developed by a broad industry group including the Danish EPA, the Danish Regions, the Danish Nature Agency, the Technical University of Denmark, and consultants - and the framework has been widely accepted by the professional community in Denmark. The concepts are quite general and can be applied in other countries facing similar challenges. PMID:24739894

Overheu, Niels Døssing; Tuxen, Nina; Flyvbjerg, John; Aabling, Jens; Andersen, Jens Asger; Pedersen, Jørn K; Thyregod, Tina; Binning, Philip J; Bjerg, Poul L

2014-07-01

345

Water quality along a river continuum subject to point and diffuse sources  

NASA Astrophysics Data System (ADS)

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.

Neal, Colin; Jarvie, Helen P.; Love, Alison; Neal, Margaret; Wickham, Heather; Harman, Sarah

2008-02-01

346

Isotopic Effects on the Temperature of the Triple Point of Water  

NASA Astrophysics Data System (ADS)

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 cells with isotopic analyses and relevant results corrected for isotopic composition, employing the isotope correction algorithm recommended by the CCT, is described. The results indicate that, after application of the corrections, the maximum temperature difference between the cells drops from 0.10 mK to 0.02 mK and that these cells are in good agreement within 0.02 mK. Also, temperature deviations arising from isotopic variations fall in the range from -55.9 ?K to + 40.7 ?K. We consider that the distillation temperature and degassing time of the production procedure lead to isotopic variations.

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

2008-02-01

347

Size Control in Production and Freeze-Drying of Poly-?-Caprolactone Nanoparticles.  

PubMed

This work is focused on the control of poly-?-caprolactone nanoparticle characteristics, notably size and size distribution, in both the production and preservation (by using freeze-drying) stages. Nanoparticles were obtained by employing the solvent displacement method in a confined impinging jets mixer. The effect of several operating conditions, namely, initial polymer concentration and solvent-to-antisolvent flow rate ratio, and the influence of postprocessing conditions, such as final dilution and solvent evaporation, on nanoparticle characteristics was investigated. Further addition of antisolvent (water) after preparation was demonstrated to be effective in obtaining stable nanoparticles, that is, avoiding aggregation that would result in larger particles. On the contrary, solvent (acetone) evaporation was shown to have a small effect on the final nanoparticle characteristics. Eventually, freeze-drying of the solutions containing nanoparticles, after solvent evaporation, was also investigated. To ensure maximum nanoparticles stability, lyoprotectants (e.g., sucrose and mannitol) and steric stabilizers (e.g., Cremophor EL and Poloxamer 388) had to be added to the suspensions. The efficacy of the selected lyoprotectants, in the presence (or absence) of steric stabilizers, and in various concentrations, to avoid particle aggregation during the freeze-drying process was investigated, thus pointing to the optimal formulation. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci. PMID:24737658

Zelenková, Tereza; Fissore, Davide; Marchisio, Daniele L; Barresi, Antonello A

2014-06-01

348

Freezing of Aqueous Polyvinylpyrrolidone Solutions.  

National Technical Information Service (NTIS)

The freezing of aqueous polyvinylpyrrolidone solutions was studied by means of differential thermal analysis, dilatometry and calorimetry. A differential thermal analysis apparatus for use at low temperatures was constructed. A fast method for the determi...

H. H. G. Jellinek S. Y. Fok

1967-01-01

349

Benefits and feasibility of effluent trading between point sources: An analysis in support of Clean Water Act reauthorization. Draft report  

Microsoft Academic Search

To prepare for reauthorization of the Clean Water Act, the U.S. Environmental Protection Agency (EPA) commissioned a series of studies of market-based incentive approaches to water pollution abatement. The study addresses one such approach: allowing municipal and industrial point sources to meet water quality goals by trading; i.e., by creating a market to buy and sell allowances to discharge pollutants.

M. Luttner; M. Podar

1992-01-01

350

Significant variability among bulls in the sperm membrane permeability for water and glycerol: possible implications for semen freezing protocols for individual males.  

PubMed

The aim of this study was to test the hypothesis that bulls have significant intra-individual differences in the hydraulic conductivity (L(p)) and permeability coefficient for glycerol (P(s)) of the sperm cell membrane. The permeability parameters were determined at 22, 10, and 0 degrees C of sperm from 7 Holstein Frisian artificial insemination (AI) bulls, using four ejaculates per bull. A stopped-flow approach was applied to provide temporal resolution sufficient to measure rapid cell volume changes under anisosmotic conditions in the absence or presence of glycerol. This technique utilizes a concentration-dependent self-quenching entrapped fluorophore. The resulting cell volume changes were used in three-parameter fitting calculations to compute L(p) in the absence glycerol, and L(p) in the presence of glycerol (L(p)(gly)) and P(s). Averaged over all bulls, L(p) in the absence of glycerol was 0.28+/-0.01, 0.15+/-0.01 and 0.10+/-0.01 microm min(-1)atm(-1) (mean+/-SD) at 22, 10 and 0 degrees C, respectively, yielding an Arrhenius activation energy (E(a)) of 7.39 kcal/mol. The average L(p)(gly) value at 22 degrees C, was 3.8 times lower than L(p) in the absence of glycerol (P<0.05). L(p)(gly), P(s), and the reflection coefficient (sigma) at 22 degrees C were 0.073+/-0.015 microm min(-1)atm(-1), 0.80+/-0.33 x 10(-3)cm min(-1), and 0.92+/-0.10 (mean+/-SD), respectively. Subsequent experiments were performed at 10 and 0 degrees C. Activation energies for L(p)(gly) and P(s) were 10.08 and 8.77 kcal/mol, respectively. The significant differences between individual bulls in L(p) and P(s) indicate that individual males may require individual adjustments of the cooling protocol. Application of these data in a theoretical model to simulate the osmotic events during freezing resulted in predicted optimal cooling rates in the range of published empirical values. PMID:17097627

Chaveiro, A; Liu, J; Engel, B; Critser, J K; Woelders, H

2006-12-01

351

Freeze-drying processes and wind erodibility of a clay loam soil in southern Alberta  

Microsoft Academic Search

Freeze-drying has been implicated as a factor causing soil aggregate breakdown on the Canadian Prairies and northern Great Plains. Aggregates of a Dark Brown Chernozemic clay loam soil sampled in October 1993 and January and April 1994 were subjected to repeated cycles of wetting (to 0.1, 0.2 and 0.3 kg kg-1 water contents) freezing, and freeze-drying under laboratory conditions. The

M S. Bullock; F. J. Larney; Sean M. McGinn; R Cesar C. Izaurralde

1999-01-01

352

Validation of Aura Microwave Limb Sounder stratospheric water vapor measurements by the NOAA frost point hygrometer  

NASA Astrophysics Data System (ADS)

between stratospheric water vapor measurements by NOAA frost point hygrometers (FPHs) and the Aura Microwave Limb Sounder (MLS) are evaluated for the period August 2004 through December 2012 at Boulder, Colorado, Hilo, Hawaii, and Lauder, New Zealand. Two groups of MLS profiles coincident with the FPH soundings at each site are identified using unique sets of spatiotemporal criteria. Before evaluating the differences between coincident FPH and MLS profiles, each FPH profile is convolved with the MLS averaging kernels for eight pressure levels from 100 to 26 hPa (~16 to 25 km) to reduce its vertical resolution to that of the MLS water vapor retrievals. The mean FPH - MLS differences at every pressure level (100 to 26 hPa) are well within the combined measurement uncertainties of the two instruments. However, the mean differences at 100 and 83 hPa are statistically significant and negative, ranging from -0.46 ± 0.22 ppmv (-10.3 ± 4.8%) to -0.10 ± 0.05 ppmv (-2.2 ± 1.2%). Mean differences at the six pressure levels from 68 to 26 hPa are on average 0.8% (0.04 ppmv), and only a few are statistically significant. The FPH - MLS differences at each site are examined for temporal trends using weighted linear regression analyses. The vast majority of trends determined here are not statistically significant, and most are smaller than the minimum trends detectable in this analysis. Except at 100 and 83 hPa, the average agreement between MLS retrievals and FPH measurements of stratospheric water vapor is better than 1%.

Hurst, Dale F.; Lambert, Alyn; Read, William G.; Davis, Sean M.; Rosenlof, Karen H.; Hall, Emrys G.; Jordan, Allen F.; Oltmans, Samuel J.

2014-02-01

353

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

Microsoft Academic Search

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

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

2006-01-01

354

A critical evaluation of two point-of-use water treatment technologies: can they provide water that meets WHO drinking water guidelines?  

PubMed

Point-of-use (POU) technologies have been proposed as solutions for meeting the Millennium Development Goal (MDG) for safe water. They reduce the risk of contamination between the water source and the home, by providing treatment at the household level. This study examined two POU technologies commonly used around the world: BioSand and ceramic filters. While the health benefits in terms of diarrhoeal disease reduction have been fairly well documented for both technologies, little research has focused on the ability of these technologies to treat other contaminants that pose health concerns, including the potential for formation of contaminants as a result of POU treatment. These technologies have not been rigorously tested to see if they meet World Health Organization (WHO) drinking water guidelines. A study was developed to evaluate POU BioSand and ceramic filters in terms of microbiological and chemical quality of the treated water. The following parameters were monitored on filters in rural Cambodia over a six-month period: iron, manganese, fluoride, nitrate, nitrite and Escherichia coli. The results revealed that these technologies are not capable of consistently meeting all of the WHO drinking water guidelines for these parameters. PMID:20705976

Murphy, Heather M; McBean, Edward A; Farahbakhsh, Khosrow

2010-12-01

355

Preparation of the nematode-trapping fungus, Arthrobotrys oligospora, for scanning electron microscopy by freeze substitution.  

PubMed

A freeze-substitution technique for preparing fungal specimens for scanning electron microscopy is described. This involves cryofixation in liquid nitrogen, freeze substitution in methanol at -20 degrees C and critical-point drying. The trapping complexes and conidiophores of the nematophagous fungus Arthrobotrys oligospora are well preserved and retain their normal three-dimensional arrangement. PMID:2352273

Wharton, D A; Murray, D S

1990-04-01

356

Review: freeze concentration technology applied to dairy products.  

PubMed

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

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

2011-02-01

357

Freezing efficiency of Silver Iodide, ATD and Kaolinite in the contact freezing mode  

NASA Astrophysics Data System (ADS)

The importance of heterogeneous ice nucleation via contact freezing is one of the open questions in the atmospheric science community. In our laboratory, we built the Collision Nucleation CHamber (CLINCH) (Ladino et al. 2011) in which falling cloud droplets can collide with aerosol particles. In this study, contact freezing experiments are conducted to investigate the ice nucleation ability of silver iodide (AgI), kaolinite and Arizona Test Dust (ATD). Silver iodide has been known for its ice nucleation ability since 1940s (Vonnegut 1947) while kaolinite is a clay mineral and known to be a moderate ice nucleus. ATD is a commercial dust sample used by many groups to compare different setups. In CLINCH, size selected aerosol particles collide with water droplets of 80 µm diameter. With the extension in chamber length it is possible to vary the interaction time of ice nuclei and the droplets. Our experiments are performed between -10 to -36 ºC for various concentrations of ice nuclei and different interaction times. The frozen fraction of the droplets is determined using the custom-made depolarization detector IODE (Nicolet et al., 2010). Depolarization of linearly polarized incident laser light is used to determine the ratio of frozen droplets to all droplets. Frozen fractions of the three particle types with different residence times from CLINCH will be presented in this study. The number of collisions between a single droplet and several aerosol particles can be calculated by accounting for the theoretical collision efficiency at the experimental conditions in order to obtain the freezing efficiency (frozen fraction/number of collisions). Nucleation efficiency is compared with other contact freezing studies and with immersion freezing

Nagare, Baban; Marcolli, Claudia; Stetzer, Olaf; Lohmann, Ulrike

2014-05-01

358

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

PubMed

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

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

1994-08-01

359

Encapsulation and sustained release from biodegradable microcapsules made by emulsification/freeze drying and spray/freeze drying.  

PubMed

Hollow biodegradable poly(DL-lactide) (PLA) particles with porous shell walls were prepared by freeze drying small droplets of PLA solution formed by emulsification or spraying. The hollow freeze-dried particles were dispersed in water, and the resulting aqueous suspensions were exposed to plasticizing solvents, either dichloromethane or compressed carbon dioxide. The plasticizing solvent causes the pores in the shell wall to close, forming microcapsules surrounding an aqueous core. A water soluble drug, procaine hydrochloride, was successfully encapsulated in the microcapsule core. The encapsulation efficiency is affected by the hollow particle morphology, amount of solvent used, solvent exposure time, surfactant, and method of dispersing the freeze-dried particles in water. The encapsulation process is explained in terms of interfacial free energy of the hollow particles and mobility of the plasticized polymer. Controlled release of procaine hydrochloride from the microcapsules into phosphate buffer solution was observed. The microcapsules had a small burst release, with the remainder of encapsulated drug slowly released over 9 days. The novel hollow PLA particles produced by emulsification/freeze drying and spray/freeze drying can potentially be used as vehicles for controlled release. PMID:19423128

Yin, Weisi; Yates, M Z

2009-08-01

360

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

PubMed

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

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

2012-09-01

361

The osmotic rupture hypothesis of intracellular freezing injury.  

PubMed Central

A hypothesis of the nature of intracellular ice formation is proposed in which the osmotically driven water efflux that occurs in cells during freezing (caused by the increased osmotic pressure of the extracellular solution in the presence of ice) is viewed as the agent responsible for producing a rupture of the plasma membrane, thus allowing extracellular ice to propagate into the cytoplasm. This hypothesis is developed into a mathematical framework and the forces that are present during freezing are compared to the forces which are required to rupture membranes in circumstances unrelated to low temperatures. The theory is then applied to systems which have been previously studied to test implications of the theory on the nature of intracellular ice formation. The pressure that develops during freezing due to water flux is found to be sufficient to cause a rupture of the plasma membrane and the theory gives an accurate description of the phenomenology of intracellular ice formation.

Muldrew, K; McGann, L E

1994-01-01

362

Thermal stresses from large volumetric expansion during freezing of biomaterials.  

PubMed

Thermal stresses were studied in freezing of biomaterials containing significant amounts of water. An apparent specific heat formulation of the energy equation and a viscoelastic model for the mechanics problem were used to analyze the transient axi-symmetric freezing of a long cylinder. Viscoelastic properties were measured in an Instron machine. Results show that, before phase change occurs at any location, both radial and circumferential stresses are tensile and keep increasing until phase change begins. The maximum principal tensile stress during phase change increases with a decrease in boundary temperature (faster cooling). This is consistent with experimentally observed fractures at a lower boundary temperature. Large volumetric expansion during water to ice transformation was shown to be the primary contributor to large stress development. For very rapid freezing, relaxation may not be significant, and an elastic model may be sufficient. PMID:10412455

Shi, X; Datta, A K; Mukherjee, Y

1998-12-01

363

Synchrotron X-Ray Visualisation of Ice Formation in Insects during Lethal and Non-Lethal Freezing  

PubMed Central

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.

Sinclair, Brent J.; Gibbs, Allen G.; Lee, Wah-Keat; Rajamohan, Arun; Roberts, Stephen P.; Socha, John J.

2009-01-01

364

Infiltration from a surface point source and drip irrigation: 1. The midpoint soil water pressure  

NASA Astrophysics Data System (ADS)

Bresler [1978] proposed a procedure for drip irrigation design which is focused on the midpoint soil water pressure hc. We present a practical field test of this approach in order to evaluate the validity of the underlying assumptions. The simulated hc values were obtained from Raats' [1971] steady state theory for 32 points in the field where the hydraulic conductivity parameters Ks and ?were measured. The hc values were measured at the same locations during microirrigation of a maize crop. Measured hc's appear to be lower than the simulated ones, especially late in the season. The measured spatial variability in hc appeared to be higher than the simulated ones. This could well have been caused by root uptake activity, which is not considered in the analysis, as well as by the large but typical drippers spacing of d = 1.00 m. Thus the tensiometers could have been beyond the practical limit of wetting. Consequences for design and management are important. For design, even if a high hc value is chosen, there is no real guarantee that the wetting would be effective at the midpoint. For irrigation management, tensiometer placement too far from the dripper would lead to overirrigation, so for a large dripper spacing d, the midpoint placement is not judicious.

Revol, P.; Vauclin, M.; Vachaud, G.; Clothier, B. E.

1997-08-01

365

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

PubMed

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

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

2012-12-01

366

Designing a Policy Mix and Sequence for Mitigating Agricultural NonPoint Source Pollution in a Water Supply Catchment  

Microsoft Academic Search

Agricultural non-point source pollution, common in water supply catchments worldwide, can have significant environmental and\\u000a human health impacts, and its mitigation poses a challenge for policymakers. We used deliberative multi-criteria evaluation\\u000a (DMCE) to identify a mix and sequence of policy instruments (or policy design) to address agricultural non-point source pollution using a case study of Cryptosporidium contamination in the Myponga

Brett A. Bryan; John M. Kandulu

2011-01-01

367

Method for calibrating copper-constantan thermocouples at negative temperatures by means of the boiling point of water  

Microsoft Academic Search

Conclusions 1.The suggested method for calibrating copper-constantan thermocouples is based on the linear relationship of corrections to the corresponding thermal emf evaluated at a single point.2.Temperatures in the negative range (0 to -200°C) are calibrated by means of the boiling point of water with an error of ±0.3°C.3.The interpolation of the thermal emf in the range from zero to the

A. P. Bondareva

1969-01-01

368

Radial interval chance-constrained programming for agricultural non-point source water pollution control under uncertainty  

Microsoft Academic Search

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

Q. Tan; G. H. Huang; Y. P. Cai

2011-01-01

369

Effects of a Proprietary Freeze-Dried Water Extract of Eurycoma longifolia (Physta) and Polygonum minus on Sexual Performance and Well-Being in Men: A Randomized, Double-Blind, Placebo-Controlled Study  

PubMed Central

Background. Physta is a proprietary product containing a freeze-dried water extract of Eurycoma longifolia (tongkat ali), which is traditionally used as an energy enhancer and aphrodisiac. We aim to evaluate a 300?mg combination of Physta and Polygonum minus, an antioxidant, with regard to sexual performance and well-being in men. Methods. Men that aged 40–65 years were screened for this 12-week randomized, double-blind, placebo-controlled, parallel-group study. Outcome measures included validated questionnaires that aimed to evaluate erectile function, satisfaction with intervention, sexual intercourse performance, erectile hardness, mood, and overall quality of life. Results. 12 subjects in the active group and 14 in the placebo group completed the study. Significant improvements were noted in scores for the Sexual Intercourse Attempt diary, Erection Hardness Scale, Sexual Health Inventory of Men, and Aging Male Symptom scale (P < 0.05 for all). Three adverse events were reported in the active group and four in the placebo group, none of which were attributed to study product. Laboratory evaluations, including liver and kidney function testing, showed no clinically significant abnormality. Conclusion. Supplementation for twelve weeks with Polygonum minus and the proprietary Eurycoma longifolia extract, Physta, was well tolerated and more effective than placebo in enhancing sexual performance in healthy volunteers.

Udani, Jay K.; George, Annie A.; Musthapa, Mufiza; Pakdaman, Michael N.; Abas, Azreena

2014-01-01

370

Freezing Tolerance of Citrus, Spinach, and Petunia Leaf Tissue 1  

PubMed Central

Seasonal variations in freezing tolerance, water content, water and osmotic potential, and levels of soluble sugars of leaves of field-grown Valencia orange (Citrus sinensis) trees were studied to determine the ability of citrus trees to cold acclimate under natural conditions. Controlled environmental studies of young potted citrus trees, spinach (Spinacia pleracea), and petunia (Petunia hybrids) were carried out to study the water relations during cold acclimation under less variable conditions. During the coolest weeks of the winter, leaf water content and osmotic potential of field-grown trees decreased about 20 to 25%, while soluble sugars increased by 100%. At the same time, freezing tolerance increased from lethal temperature for 50% (LT50) of ?2.8 to ?3.8°C. In contrast, citrus leaves cold acclimated at a constant 10°C in growth chambers were freezing tolerant to about ?6°C. The calculated freezing induced cellular dehydration at the LT50 remained relatively constant for field-grown leaves throughout the year, but increased for leaves of plants cold acclimated at 10°C in a controlled environment. Spinach leaves cold acclimated at 5°C tolerated increased cellular dehydration compared to nonacclimated leaves. Cold acclimated petunia leaves increased in freezing tolerance by decreasing osmotic potential, but had no capacity to change cellular dehydration sensitivity. The result suggest that two cold acclimation mechanisms are involved in both citrus and spinach leaves and only one in petunia leaves. The common mechanism in all three species tested was a minor increase in tolerance (about ?1°C) resulting from low temperature induced osmotic adjustment, and the second in citrus and spinach was a noncolligative mechanism that increased the cellular resistance to freeze hydration.

Yelenosky, George; Guy, Charles L.

1989-01-01

371

Freezing D2O clay gels.  

PubMed

To obtain the T1 surface value in smectites/D2O diluted suspensions or gels, as was obtained on a monolayer deuterated clay, we freeze them. The broad Pake's doublets similar to ice doublets and with the same T1 show that we can separate frozen from unfrozen D2O. The latter exhibits a narrower line and a single T1 and is attributed to the liquid surface water layer in rapid exchange with the nearby supercooled water, the quantity of which diminishes with the lowering of the temperature depending on the gel porosity. It is possible to measure the supercooled water quantity and to correct the T1 measured values to extract the T1 surface. The value extrapolated at room temperature allows the complete clay surface area measurement. The example of a montmorillonite is given and a comparison with laponite is made. PMID:9803898

Letellier, M

1998-01-01

372

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

Microsoft Academic Search

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

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

2008-01-01

373

Quantitative Evaluation of Experimental Results an the Heterogeneous Freezing Nucleation of Supercooled Liquids  

Microsoft Academic Search

Freezing experiments using large numbers of small drops are frequently used for the study of both homogeneous and heterogeneous nucleation of water and of other substances. For heterogeneous nucleation, the spread in the observed freezing temperatures of drops has been shown to arise from the presence of nuclei of different activities in the sample. In the past no quantitative assessment

Gabor Vali

1971-01-01

374

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

Microsoft Academic Search

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

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

1998-01-01

375

Plant Viability as a Function of Temperature Stress (The Richards Function Applied to Data from Freezing Tests of Growing Shoots).  

PubMed Central

Frost resistance of growing Salix viminalis L. shoots was determined by rating mortality percentage under two commonly used freezing conditions: a condition in which plants were encased in crushed ice and another in which plants were moistened with tap water prior to freezing. The mortality-temperature data were fitted with a logistic function (having a fixed inflection point halfway between the asymptotes) and with a Richards function, which is a double asymptotic sigmoid function with a variable inflection point. Different frost resistance curves were obtained, depending on the freezing conditions used. However, conditions were inadequate for efficient ice nucleation under either condition. This implies that the applied freezing conditions are not suitable when the purpose is to induce and duplicate early ice crystal formation conditions. The Richards derivatives were negatively skewed in the one case and positively skewed in the other case, giving inflection points, as a function of the upper asymptote, situated at 0.37 when shoots were frosted in the presence of ice and at 0.81 when shoots were frozen in the presence of added moisture. These values differed significantly from 0.50, through which the logistic function would have forced the curves. Because of the significant asymmetry in these frost-resistance curves, the Richards function led to a more accurate reflection of the temperature-mortality course of growing Salix stems than the logistic function. The Richards function possesses the flexibility needed to describe plant injury response in terms of physical and plant physiological mechanisms. Therefore, the Richards function is recommended rather than the logistic function for the assessment of frost resistance.

Von Fircks, H. A.; Verwijst, T.

1993-01-01

376

Point of use household drinking water filtration: A practical, effective solution for providing sustained access to safe drinking water in the developing world.  

PubMed

The lack of safe water creates a tremendous burden of diarrheal disease and other debilitating, life-threatening illnesses for people in the developing world. Point-of-use (POU) water treatment technology has emerged as an approach that empowers people and communities without access to safe water to improve water quality by treating it in the home. Several POU technologies are available, but, except for boiling, none have achieved sustained, large-scale use. Sustained use is essential if household water treatment technology (HWT) is to provide continued protection, but it is difficult to achieve. The most effective, widely promoted and used POU HWTs are critically examined according to specified criteria for performance and sustainability. Ceramic and biosand household water filters are identified as most effective according to the evaluation criteria applied and as having the greatest potential to become widely used and sustainable for improving household water quality to reduce waterborne disease and death. PMID:18605542

Sobsey, Mark D; Stauber, Christine E; Casanova, Lisa M; Brown, Joseph M; Elliott, Mark A

2008-06-15

377

Improvement of HS-SPME for analysis of volatile organic compounds (VOC) in water samples by simultaneous direct fiber cooling and freezing of analyte solution  

Microsoft Academic Search

The sensitivity and precision of headspace solid-phase micro extraction (HS-SPME) at an analyte solution temperature (T\\u000a as) of +35 C and a fiber temperature (T\\u000a fiber) of +5 C were compared with those for HS-SPME at T\\u000a as and T\\u000a fiber of ?20 C for analysis of the volatile organic compounds benzene, 1,1,1-trichloroethane, trichloroethylene, toluene, o-xylene, ethylbenzene, m\\/p-xylene, and tetrachloroethylene in water samples.

Elke Fries; Wilhelm Püttmann

2006-01-01

378

Measuring and modeling hemoglobin aggregation below the freezing temperature.  

PubMed

Freezing of protein solutions is required for many applications such as storage, transport, or lyophilization; however, freezing has inherent risks for protein integrity. It is difficult to study protein stability below the freezing temperature because phase separation constrains solute concentration in solution. In this work, we developed an isochoric method to study protein aggregation in solutions at -5, -10, -15, and -20 °C. Lowering the temperature below the freezing point in a fixed volume prevents the aqueous solution from freezing, as pressure rises until equilibrium (P,T) is reached. Aggregation rates of bovine hemoglobin (BHb) increased at lower temperature (-20 °C) and higher BHb concentration. However, the addition of sucrose substantially decreased the aggregation rate and prevented aggregation when the concentration reached 300 g/L. The unfolding thermodynamics of BHb was studied using fluorescence, and the fraction of unfolded protein as a function of temperature was determined. A mathematical model was applied to describe BHb aggregation below the freezing temperature. This model was able to predict the aggregation curves for various storage temperatures and initial concentrations of BHb. The aggregation mechanism was revealed to be mediated by an unfolded state, followed by a fast growth of aggregates that readily precipitate. The aggregation kinetics increased for lower temperature because of the higher fraction of unfolded BHb closer to the cold denaturation temperature. Overall, the results obtained herein suggest that the isochoric method could provide a relatively simple approach to obtain fundamental thermodynamic information about the protein and the aggregation mechanism, thus providing a new approach to developing accelerated formulation studies below the freezing temperature. PMID:23808610

Rosa, Mónica; Lopes, Carlos; Melo, Eduardo P; Singh, Satish K; Geraldes, Vitor; Rodrigues, Miguel A

2013-08-01

379

Crossover behavior in micellar solutions with lower critical demixing point: Broadband ultrasonic spectrometry of the isobutoxyethanol-water system  

Microsoft Academic Search

The aggregation kinetics of isobutoxyethanol-water mixtures with lower critical demixing point has been investigated. Two types of kinetics have been observed, a diffusion-controlled formation of micellar species and the formation of a microheterogeneous liquid structure, governed by fluctuations in the local concentration. Ultrasonic attenuation spectra of isobutoxyethanol-water mixtures have been measured between 100 kHz and 2 GHz at 25 °C

K. Menzel; S. Z. Mirzaev; U. Kaatze

2003-01-01

380

Freeze-dried microarterial allografts  

SciTech Connect

Rehydrated freeze-dried microarterial allografts were implanted to bridge arterial defects using New Zealand White rabbits as the experimental model. Segments of artery from the rabbit ear and thigh were harvested and preserved for a minimum of 2 weeks after freeze-drying. These allografts, approximately 1 mm in diameter and ranging from 1.5 to 2.5 cm in length, were rehydrated and then implanted in low-pressure and high-pressure arterial systems. Poor patency was noted in low-pressure systems in both allografts and autografts, tested in 12 rabbits. In the high-pressure arterial systems, allografts that were freeze-dried and reconstituted failed in a group of 10 rabbits with an 8-week patency rate of 30 percent. Gamma irradiation in an effort to reduce infection and antigenicity of grafts after freeze-drying was associated with a patency rate of 10 percent at 8 weeks in this system in another group of 10 rabbits. Postoperative cyclosporin A therapy was associated with a patency rate of 22.2 percent in the high-pressure arterial system in a 9-rabbit group. Control autografts in this system in a group of 10 rabbits showed a 100 percent patency at 8 weeks. Microarterial grafts depend on perfusion pressure of the vascular bed for long-term patency. Rehydrated freeze-dried microarterial allografts do not seem to function well in lengths of 1 to 2.5 cm when implanted in a high-pressure arterial system. Freeze-dried arterial allografts are probably not antigenic.

Raman, J.; Hargrave, J.C.

1990-02-01

381

Point estimation of soil water infiltration process using Artificial Neural Networks for some calcareous soils  

NASA Astrophysics Data System (ADS)

SummaryInfiltration process is one of the most important components of the hydrological cycle. The direct measurement of infiltration is laborious, time consuming, expensive, and often involves large spatial and temporal variability. Thus, any indirect estimation of this process is quite helpful. The main objective of this study was to predict the cumulative infiltration at specific time steps, using readily available soil data and Artificial Neural Networks (ANNs). 210 double ring infiltration data were collected from different regions of Iran. Basic soil properties of the two upper pedogenic layers (A and B horizons) including initial soil water content, soil water contents at field capacity (-33 kPa) and permanent wilting point (-1500 kPa), bulk density, particle-size distributions, organic carbon, gravel content (>2 mm size), and CaCO3 content were determined. The feedforward multilayer perceptron ANN model was used to predict the cumulative infiltration at 5, 10, 15, 20, 30, 45, 60, 90, 120, 150, 180, 210, 240, and 270 min after the start of the infiltration experiment and at the time of the basic infiltration rate. The developed ANN models were categorized to type I and type II ANN models. The basic soil properties of the first upper soil horizon were hierarchically used as inputs to develop type I ANN models. In contrast, the type II ANN models were developed while the available soil properties of the two upper soil horizons were implemented as inputs using principal component analysis technique. Results of the reliability test for the developed ANN models indicated that type I ANN models with a RMSE of 1.136-9.312 cm had the best performance in estimating the cumulative infiltration. Type I ANN models with the mean RMSD of 6.307 cm had the best performance in estimating the cumulative infiltration curve (CIC). Results indicated that at the 1% probability level, ANNs-derived CIC can be accepted as one of the replications of a reliable infiltration experiment. It was also concluded that compared to the Horton, Kostiakov, revised USDA-NRCS, Philip, and Green and Ampt infiltration models, the Kostiakov-Lewis model performed better to quantify the infiltration process.

Parchami-Araghi, Farzin; Mirlatifi, Seyed Majid; Ghorbani Dashtaki, Shoja; Mahdian, Mohmmad Hossein

2013-02-01

382

Heat Capacity Anomaly Near the Lower Critical Consolute Point of Triethylamine-Water  

NASA Technical Reports Server (NTRS)

The heat capacity of the binary liquid mixture triethylamine-water has been measured near its lower critical consolute point using a scanning, adiabatic calorimeter. Two data runs are analyzed to provide heat capacity and enthalpy data that are fitted by equations with background terms and a critical term that includes correction to scaling. The critical exponent a was determined to be 0.107 +/- 0.006, consistent with theoretical predictions. When alpha was fixed at 0.11 to determine various amplitudes consistently, our values of A(+) and A(-) agreed with a previous heat capacity measurement, but the value of A(-) was inconsistent with values determined by density or refractive index measurements. While our value for the amplitude ratio A(+)/ A(-) = 0.56 +/- 0.02 was consistent with other recent experimental determinations in binary liquid mixtures, it was slightly larger than either theoretical predictions or recent experimental values in liquid-vapor systems. The correction to scaling amplitude ratio D(+)/D(-) = 0.5 +/- 0.1 was half of that predicted. As a result of several more precise theoretical calculations and experimental determinations, the two-scale-factor universality ratio X, which we found to be 0.019 +/- 0.003, now is consistent among experiments and theories. A new 'universal' amplitude ratio R(sup +/-)(sub Bcr) involving the amplitudes for the specific heat was tested. Our determination of R(sup +/-)(sub Bcr) = -0.5 +/- 0.1 and R(sup -)(sub Bcr) = 1.1 +/- 0.1 is smaller in magnitude than predicted and is the first such determination in a binary fluid mixture.

Flewelling, Anne C.; DeFonseka, Rohan J.; Khaleeli, Nikfar; Partee, J.; Jacobs, D. T.

1996-01-01

383

Freezing and thawing porous media: experimental study with a dielectric capacitive method  

NASA Astrophysics Data System (ADS)

A capacitive sensor-based apparatus has been used to study the ice/water phase change in consolidated porous media subjected to freezing and thawing. This technique relies on the dielectric properties of water, ice, air, and the mineral substrate in the radio-frequency range. It gives directly the freezing and thawing temperature depressions and indirectly provides an estimation of pore size distribution through the Gibbs-Thomson relation. It also holds good promise for evaluating the amount of liquid water in frozen porous media by combining drying and freezing tests. To cite this article: T. Fen-Chong, A. Fabbri, C. R. Mecanique 333 (2005).

Fen-Chong, Teddy; Fabbri, Antonin

2005-05-01

384

Understanding the structure of porous materials created by freeze casting  

Microsoft Academic Search

When a suspension of colloidal particles in water freezes, dendrites of ice with high aspect ratios are formed which can either engulf or reject the particles based on their size and the velocity of the advancing ice front. As the particles are pushed between the dendrites, concentrated regions of colloidal particles are formed. Recent experiments have shown that this can

Stephen Barr; Erik Luijten

2009-01-01

385

Freezing effect on shear strength of clayey soils  

Microsoft Academic Search

The design and construction of earth structures influenced seasonally by subzero temperatures requires the determination of mechanical properties of the construction materials under appropriate thermal conditions. Water saturated materials exhibit a zone of partially frozen soil at the frozen-unfrozen soil interface. To define the critical failure surface and governing shear strength in this zone, the effects of partial freezing on

K. A. Czurda; M. Hohmann

1997-01-01

386

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...

387

PROCEEDINGS OF THE CONFERENCE ON POINT-OF-USE TREATMENT OF DRINKING WATER HELD AT CINCINNATI, OHIO ON OCTOBER 6-8, 1987  

EPA Science Inventory

A Conference on Point-of-Use Treatment of Drinking Water was held on October 6-8, 1987, to provide information on the application of point-of-use (POU) and point-of-entry (POE) systems for treating drinking water to a wide-cross section of people interested in the technology. The...

388

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...

389

CLOUD POINT EXTRACTION OF AROMATIC AMINES FROM ENVIRONMENTAL WATER SAMPLES COUPLED WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY  

Microsoft Academic Search

An efficient and environmentally friendly analytical methodology was developed for the extraction and preconcentration of three aromatic amines from environmental water samples coupled with high performance liquid chromatography. It is based on the cloud point extraction of aromatic amines using non–ionic surfactant Triton X-114 as an extraction solvent. Extraction parameters such as the type and amount of surfactant, extraction temperature,

Dandan Han; Baokun Tang; Kyung Ho Row

2012-01-01

390

Effects of time and point-of-use devices on arsenic levels in Southeastern Michigan drinking water, USA.  

PubMed

Health effects associated with chronic, low-level exposures to arsenic in drinking water (<100 microg/L) remain unclear, in part due to uncertainties in assessing exposure. Drinking water concentrations have been used to assess past exposure to arsenic in epidemiological studies, under the assumption that a single measurement can be used to estimate historical exposure. This study aims to better understand (1) temporal variability in arsenic concentrations in drinking water and (2) the impact of point-of-use (POU) treatment devices on arsenic exposure measurements, and on reliability of the exposure measurement for population-level studies. Multiple drinking water samples were collected at two points in time (an average of fourteen months apart) for 261 individuals enrolled in a case-control study of arsenic exposure and bladder cancer in Michigan. Sources of drinking water included private wells (n = 221), public water supplies (n = 33), and bottled water (n = 7); mean arsenic concentration was highest in private wells (7.28 microg/L) and lowest in bottled water samples (0.28 microg/L). Arsenic concentrations in primary drinking water samples were highly correlated (r = 0.88, p < 0.0001, n = 196), with 3% of the water sources exceeding the United States Environmental Protection Agency's Maximum Contaminant Level (MCL) in one sample but not in the other sample. Measurement reproducibility did not vary by type of POU device (e.g., softener, filter, reverse osmosis system). Arsenic concentrations did differ, however, between samples treated with POU devices and untreated samples taken on the same day. Substantial differences in arsenic concentrations were consistently observed for reverse osmosis systems; other POU devices had variable effects on arsenic concentrations. These results indicate that while a single residential arsenic measurement may be used to represent exposure in this region, researchers must obtain information on changes in water source and POU treatment devices to better characterize population exposures over time. PMID:16750243

Slotnick, Melissa J; Meliker, Jaymie R; Nriagu, Jerome O

2006-10-01

391

FREEZING AND THAWING RESISTANCE OF CONCRETE WITH INITIAL CRACK  

NASA Astrophysics Data System (ADS)

Freezing and thawing resistance of concrete with an initial crack was investigated. The specimens were classified into plane concrete, fiber reinforced concrete, and reinforced concrete. In the tests of plane concrete with an initial crack, the crack grows seriously by the frozen expansion pressure of the water infiltrated into the crack, though the concrete material had high resistance to freezing and thawing. In the experimental results of fiber reinforced concrete, the long polypropylene fiber was useful to prevent the spalling of concrete cover, though the crack growth was not prevented. Moreover, in the experimental results of reinforced concrfete, it was shown that the crack growth was effectively prevented by steel reinforcing bar.

Naito, Hideki; Hayashi, Hiroshi; Saiki, Yusuke; Sando, Koichi; Koga, Hideyuki; Suzuki, Motoyuki

392

Determination of trace nickel in water samples by cloud point extraction preconcentration coupled with graphite furnace atomic absorption spectrometry.  

PubMed

A new method based on the cloud point extraction (CPE) preconcentration and graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of trace nickel in water samples. When the micelle solution temperature is higher than the cloud point of surfactant p-octylpolyethyleneglycolphenyether (Triton X-100), the complex of Ni2+ with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) could enter surfactant-rich phase and be concentrated, then determined by GFAAS. The main factors affecting the cloud point extraction were investigated in detail. An enrichment factor of 27 was obtained for the preconcentration of Ni2+ with 10 mL solution. Under the optimal conditions, the detection limit of Ni2+ is 0.12 ng mL(-1) with R.S.D. of 4.3% (n = 10, c = 100 ng mL(-1)). The proposed method was applied to determination of trace nickel in water samples with satisfactory results. PMID:16704902

Sun, Zhimei; Liang, Pei; Ding, Qiong; Cao, Jing

2006-09-21

393

Investigation of water quality parameters at selected points on the Tennessee River  

NASA Technical Reports Server (NTRS)

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.

1972-01-01

394

Programmed-Temperature Normal Freezing  

Microsoft Academic Search

A normal freezing apparatus is described where the cooling-bath temperature can be programmed between 0.5 × 10 and 6.0°C\\/mm. Runs with n-hexadecane\\/n-tetradecane test mixtures indicate that improved efficiencies result from programming the cooling bath during the run.

T. H. Gouw

1967-01-01

395

Water Quality vs. Sanitation Accessibility: What is the most effective intervention point for preventing cholera in Dhaka, Bangladesh?  

NASA Astrophysics Data System (ADS)

Every year, 3 to 5 million individuals contract cholera, an acute diarrheal infection that is caused by the ingestion of food or water containing the Vibrio cholerae bacterium. Because cholera is a waterborne disease, it can be transmitted quickly in environments with inadequate water and sanitation systems where infected waste can easily pollute drinking water. Today, Bangladesh continues to struggle with endemic cholera. Donor organizations address water and sanitation via localized initiatives, including the installation of community water collection sites (i.e. tubewells; water-boiling points; etc.). At this small-scale level, water quality and sanitation accessibility can be improved independently of one another, and when resources are limited, donors must invest in the most effective disease prevention options. This study used laboratory-confirmed cholera incidence data (2000-2009) collected by the International Centre of Diarrheal Disease Research, Bangladesh at their on-site hospital to compare the efficacy of interventions addressing water quality versus sanitation accessibility in Dhaka, Bangladesh. Data regarding use of sanitary latrines and boiling of drinking water were extracted from sequential patient interviews conducted at the Dhaka facility and used as surrogate variables for sanitation accessibility and water quality respectively. Our analysis indicates that boiling water is 10 times more effective at preventing cholera than the use of a sanitary latrine. This finding suggests that regulating water quality is perhaps more critical to cholera prevention than increasing sanitation accessibility in an urban environment like that of Dhaka. At present, WaterAid - one of Bangladesh's most significant water and sanitation donor organizations - invests the majority of its budget on improving sanitation accessibility. The World Health Organization and the United Nations Millennium Development Goals also prioritize sanitation accessibility. However, in Bangladesh, water quality must be given greater attention. As the nation's most prevalent diarrheal disease, cholera outbreaks result in incalculable lost wages and treatment expenses, taken from the pockets of an already impoverished society. Bangladesh cannot afford cholera; prevention is the only sustainable control option, and water quality is the most effective intervention point for Dhaka, Bangladesh.

Majumder, M. S.; Gute, D.; Faruque, A. S.

2011-12-01

396

Atmospheric concentrations of submicron contact-freezing nuclei  

NASA Technical Reports Server (NTRS)

Atmospheric concentrations of contact-freezing nuclei were measured using a technique primarily sensitive to submicron aerosol particles. Diffusion and phoretic forces were relied on for the capture of nuclei by supercooled drops of distilled water exposed to the sample air. Nucleus concentrations were deduced from the rate at which the drops were observed to freeze, interpreting that rate on the basis of a theoretical prediction of aerosol capture rate for different assumed sizes of the nuclei. Measurements at Laramie, Wyoming, yielded average concentrations of contact-freezing nuclei of 1.7/L at -15 C and 3.1/L at -18 C for an assumed radius of 0.01 micron for the nucleating particles.

Deshler, Terry; Vali, Gabor

1992-01-01

397

Freezing-induced fluid-matrix interaction in poroelastic material  

PubMed Central

Freezing of biological tissue is emerging in various biomedical applications. The success of these applications requires precise control of the tissue functionality, which is closely associated with the microstructure of the extracellular matrix (ECM). In the present study, the spatiotemporal effects of freezing on the ECM were experimentally and theoretically investigated by approximating biological tissue as a poroelastic material saturated with interstitial fluid. The experiments with type I collagen gel showed that its matrix underwent two distinct levels of structural changes due to freezing : enlarged pore structure of the matrix and increased collagen fibril diameters. The extent of these changes was augmented as the freezing temperature was lowered. The theoretical model suggested that the interstitial fluid might be transported toward the unfrozen region from the phase change interface due to the volumetric expansion associated with the water-ice phase change, and the transported fluid could interact with the matrix and enlarge its pore structure. The model also illustrated the effects of matrix structural properties on this interaction including initial porosity, hydraulic conductivity and elastic modulus. These results imply that an identical macroscopic freezing protocol may result in different microstructural alterations of poroelastic materials depending on the structural properties of the matrix. This may be relevant to understanding the tissue-type dependent outcomes of cryomedicine applications and be useful in designing cryomedicine applications for a wide variety of tissues.

Han, Bumsoo; Miller, Jeffrey D.; Jung, Jun K.

2008-01-01

398

A modified homogeneous freezing rate parameterization for aqueous solution droplets  

NASA Astrophysics Data System (ADS)

It is still a matter of debate wether cirrus cloud formation is dominated by heterogeneous ice nucleation, leading to low ice crystal number concentrations, or is also influenced by homogeneous freezing of solution aerosols leading to higher ice crystal number concentrations. Part of the discussion is due to the fact that current models seem to overestimate ice crystal numbers from homogeneous freezing compared to measurements, though the formation rate of cirrus ice crystals by homogeneous freezing of aqueous particles is believed to be well understood and formulated in terms of e.g. the concept of effective freezing temperatures or the water activity dependent ice nucleation rates. Series of recent cirrus cloud simulation experiments at the cloud chamber facility AIDA at the Karlsruhe Institute of Technology at temperatures between -40°C and -80°C together with process modeling studies demonstrated, that the freezing formulations tend to show a low bias in the humidity onset thresholds for homogeneous ice formation at temperatures below about 210 K, and furthermore overestimate the ice formation rate by at least a factor of 2. The experimental results will be summarized and a new empirical fit to the experimental data will be suggested for use in atmospheric models.

Moehler, O.; Benz, S.; Hoehler, K.; Wagner, R.

2012-12-01

399

????????????????????????????????????????????????????? Detection of the Water Added in Milk by Compression on Frozen Samples  

Microsoft Academic Search

The objective of this study was to develop a technique for detecting water added to raw milk, other than using conventional methods such as determination of the specific gravity or of the freezing point temperature. With the assumption that the compressive force will vary with the quantities of added water in raw milk, the experiment set up then was conducted

Suwan Homhual; Supattra Chandapradit

400

Occurrence of non-fermenting gram negative bacteria in drinking water dispensed from point-of-use microfiltration devices.  

PubMed

Introduction and objective. Many devices have been marketed in order to improve the organoleptic characteristics of tap water resulting from disinfection with chlorine derivates. The aim of the presented study was to assess the degree of contamination by non-fermenting Gram-negative bacteria (NF-GNB) of drinking water dispensed from microfiltration devices at point-of-use. Methods. Water samples were collected from 94 point-of-use water devices fitted with a filter (0.5?m pore size) containing powdered activated carbon. The microbiological contamination of water entering and leaving the microfiltered water dispensers was compared. The NF-GNB loads were correlated to Total Heterotrophic Counts (HPCs) at 37 and 22 °C, residua chlorine, and some structural and functional features of the devices. Results. NF-GNB were detected from 23% of supply water samples, 33% of still unchilled water, 33% of still chilled water and 18% of carbonated chilled water. The most frequent isolates were Pseudomonadaceae: Steno.maltophilia 30.2% of isolates, Pseudomonas 20.5%, Delftia acidovorans 13.4%, while the species more largely distributed was Ps. aeruginosa recovered from 13% of samples. The distribution of the various NF-GNB was different in the water entering and in that leaving the devices. Ps.aeruginosa and Steno.maltophilia were the predominant species in water leaving the microfiltration dispensers, probably due to their capacity to colonize the circuits and to prevail over the others. Recovery of NF-GNB was favoured by the reduction in residual chlorine of the supply water, occasional use, the absence of a bacteriostatic element in the filter and inadequate disinfection of the water lines. Conclusions. The presence of high concentrations of potentially pathogenic species of NF-GNB (Ps.aeruginosa, Steno. maltophilia, Burkhol.cepacia) in the water dispensed from microfiltration devices represents a risk of waterborne infections for vulnerable individuals. When these devices are used in environments such as hospitals, nursing homes for the elderly, etc., microbiological monitoring for the detection of NF-GNB is advisable. PMID:24742036

Zanetti, Franza; de Luca, Giovanna; Leoni, Erica; Sacchetti, Rossella

2014-04-01

401

Repeated Freeze-Thaw Cycles in Cryosurgery  

Microsoft Academic Search

FREEZING temperatures have been in use in surgery for many years as a means of local tissue destruction. Recent experimental investigation has shown that such freezing will give a reproducible area of cell death provided factors such as the temperature and the duration of application are constant. Additional virtues have been claimed for repeated, as opposed to single, freeze-thaw cycles

William Gill; James Fraser; David C. Carter

1968-01-01

402

Molten salt freeze seal. Final report  

Microsoft Academic Search

This report documents the results of the testing performed at Sandia National Laboratory, Albuquerque, New Mexico, on the applicability of a sodium freeze seal type valve stem in a molten salt environment. The freeze seal tests consisted of cycling the valve stem at set temperature intervals, checking the temperature distribution for freeze plug location, and verifying the actuator forces. In

Corugedo

1985-01-01

403

Freeze/Thaw-Induced Embolism: Probability of Critical Bubble Formation Depends on Speed of Ice Formation  

PubMed Central

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.

Sevanto, Sanna; Holbrook, N. Michele; Ball, Marilyn C.

2012-01-01

404

Freeze/Thaw-induced embolism: probability of critical bubble formation depends on speed of ice formation.  

PubMed

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

Sevanto, Sanna; Holbrook, N Michele; Ball, Marilyn C

2012-01-01

405

Infrared Monitoring of Interlayer Water in Stacks of Purple Membranes†  

PubMed Central

The thermodynamic behavior of films of hydrated purple membranes from Halobacterium salinarum and the water confined in it was studied by FTIR spectroscopy in the 180–280 K range. Unlike bulk water, water in the thin layers sandwiched between the biological membranes does not freeze at 273 K but will be supercooled to ~256 K. The melting point is unaffected, leading to hysteresis between 250 and 273 K. In its heating branch a gradually increasing light-scattering by ice is observed with rate-limiting kinetics of tens of minutes. IR spectra decomposition provided extinction coefficients for the confined water vibrational bands and their changes upon freezing. Due to the hysteresis, at any given temperature in the 255–270 K range the inter-bilayer water could be either liquid or frozen, depending on thermal history. We find that this difference affects the dynamics of the bacteriorhodopsin photocycle in the hysteresis range: the decay of the M and N states and the redistribution between them are different depending on whether or not the water was initially pre-cooled to below the freezing point. However, freezing of inter-bilayer water does block the M to N transition. Unlike the water, the purple membrane lipids do not undergo any IR-detectable phase transition in the 180–280 K range.

Dioumaev, Andrei K.; Lanyi, Janos K

2009-01-01

406

Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water.  

PubMed

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. PMID:24437876

Stinson, Jake L; Kathmann, Shawn M; Ford, Ian J

2014-01-14

407

Electrochemical Surface Potential due to Classical Point Charge Models Drives Anion Adsorption to the Air-Water Interface  

SciTech Connect

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.

Baer, Marcel D.; Stern, Abraham C.; Levin, Yan; Tobias, Douglas J.; Mundy, Christopher J.

2012-06-07

408

A Water Quality Monitoring Network Design Methodology for the Selection of Critical Sampling Points: Part I  

Microsoft Academic Search

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

R. O. Strobl; P. D. Robillard; R. D. Shannon; R. L. Day; A. J. McDonnell

2006-01-01

409

Water saturations in a Wilcox shaly reservoir sandstone, Fordoche field, Point Coupee Parish, Louisiana  

SciTech Connect

A new equation has been derived for calculation of water saturations in shaly reservoir sandstones. The equation is based on effective medium theory (EMT) and has been used successfully on a wide range of clayey, low-resistivity reservoirs. A further, independent test of saturations calculated by the equation was made for a deep Wilcox shaly reservoir at a depth of 13,176 ft (4016 m) in Fordoche field. The reservoir (W8) has a low, average resistivity of about 2.5 ohm-m and an estimated 18% clay as compared to an average resistivity of 1.5 ohm-m in an underlying water-saturated sandstone (W-10) of similar clay content. For the reservoir, calculated water saturations are in the range of 35 to 50%, increasing downward, and suggest that the shaly sandstone should produce water-free oil. For the underlying wet sandstone, the calculated water saturations range from 55 to 75% and confirm that only water should be produced. Other shaly sand equations generally give water saturations in excess of 50% for the reservoir. Water saturations calculated by the EMT equation agree well with other parameters for sandstones: reported production, core, analysis, and synthetic capillary pressures. The reservoir (W8) had an initial potential of 213 bbl of oil per day, confirming water-free oil production which could have been predicted by the EMT equation.

Berg, C.R.; Berg, R.R. [Texas A& M Univ., College Station, TX (United States)

1996-09-01

410

A simple and flexible field-tested device for housing water monitoring sensors at point discharges.  

PubMed

The Water Monitoring Enclosure (WME) provides a simple and flexible housing for many types of sensors for continuous measurements of water parameters (physical, chemical, or biological) and provides the opportunity of representative sampling for external analyses. The WME ensures a minimum internal water level and this ensures that the internal monitoring equipment remains submerged even when there is no flow into the enclosure. The limited diameter of the inflow pipe and water volume in the WME buffers the flow velocity from dramatic changes. The device ensures that the sediment entering the enclosure from the inflow will be conveyed through the enclosure with minimal sediment accumulation. The device is powered purely from natural hydraulic forces, so it requires no power source, and requires little additional maintenance beyond periodic cleaning. If desired, the WME can also measure discharge entering the device through additional modifications. Water samples were taken throughout the year to validate the effectiveness of the WME. The comparisons of the influent water to the water in the WME for all parameters were below the laboratory analysis standard error or below the limit of quantification, indicating that the water in the WME is representative of the influent water. PMID:23416594

Exner-Kittridge, Michael; Niederreiter, Richard; Eder, Alexander; Zessner, Matthias

2013-01-01

411

New Evolution Model of Enceladus Including Serpentinization and Anti-Freeze  

NASA Astrophysics Data System (ADS)

We present a new thermal evolution code with application to the Saturnian satellite Enceladus. We consider multiphase flow of water through a porous medium, radioactive heating, serpentinization, anti-freeze, hydrostatic structure and other parameters in our analysis.

Malamud, U.; Prialnik, D.

2012-05-01

412

Molecular simulation of water along the liquid--vapor coexistence curve from 25 degree C to the critical point  

SciTech Connect

Previous work has shown that the simple point-charge (SPC) model can represent the experimental dielectric constant of water. In this work, we present results of Monte Carlo simulations of SPC water in the isothermal--isobaric (NPT) ensemble and in the Gibbs ensemble. Long-range intermolecular interactions are included in these simulations by use of the Ewald summation method. When Ewald sums are used, simulated, uniphase liquid potential energies are slightly lower (in absolute value) than those obtained for a simple spherical cutoff of the intermolecular potential. The coexistence curve of SPC water is obtained from 25 to 300{degree}C. The critical constants of SPC water are estimated by adjusting the coefficients of a Wegner expansion to fit the difference between simulated liquid and vapor orthobaric densities; the estimated critical temperature is 314 {degree}C and the estimated critical density is 0.27 g/cm{sup 3}.

de Pablo, J.J.; Prausnitz, J.M. (Department of Chemical Engineering, University of California, Berkeley, CA (USA) Materials and Chemical Sciences Division, Lawrence Berkeley Laboratory, Berkeley, CA (USA)); Strauch, H.J.; Cummings, P.T. (Department of Chemical Engineering, University of Virginia, Charlottesville, VA (USA))

1990-11-15

413

Combined Water-Fertilizer Management to Minimize Non-Point Water Pollution while Achieving High Crop Production.  

National Technical Information Service (NTIS)

Greenhouse and field experiments were conducted to characterize relationships between fertilizer and water management in irrigated vegetable production in California. Greenhouse trials were conducted both in hydroponic solution culture and in soil culture...

J. Letey W. M. Jarrell

1983-01-01

414

Spatial Assessment of Water Quality in Peripheral Rivers of Dhaka City for Optimal Relocation of Water Intake Point  

Microsoft Academic Search

In order to meet the ever increasing demand of drinking water, Dhaka Water Supply Authority (DWASA) of Bangladesh has installed\\u000a a number of deep tube wells that tap the upper aquifers. However, in most parts of the city, the current groundwater abstraction\\u000a exceeds the recharge rate, causing the groundwater to be mined systematically and be depleted of its reserve. Thus,

Sayma Rahman; Faisal Hossain

2008-01-01

415

Ultrasonic Measurements of Unconsolidated Saline Sediments During Freeze/Thaw Cycles: The Seismic Properties of Cryopeg Environments  

NASA Astrophysics Data System (ADS)

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.

Dou, S.; Ajo Franklin, J. B.

2013-12-01

416

Heat pump with freeze-up prevention  

DOEpatents

What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid prevents freeze up of the second heat exchanger by keeping the temperature above the dew point; and, optionally, provides heat for efficient operation.

Ecker, Amir L. (Dallas, TX)

1981-01-01

417

Freeze indicators with a controlled temperature response  

US Patent & Trademark Office Database

A freeze indicator can include an indicator dispersion having an aqueous liquid medium and organic material indicator particles dispersed in the aqueous liquid medium. The indicator dispersion can have an initial appearance before freezing and an irreversibly different appearance after freezing and can exhibit a freeze-onset temperature of about -1.9.degree. C. or higher. Some factors helpful to providing a relatively high freeze onset temperature are employment of a proteinaceous ice-nucleating agent, control of pH, use of a protein stabilizer and control of the ratio of protein stabilizer to ice-nucleating agent.

2012-02-28

418

COMPARATIVE ANALYSIS OF THREE SUSTAINABLE POINT OF USE DRINKING WATER TREATMENT TECHNOLOGIES FOR DEVELOPING NATIONS  

EPA Science Inventory

More than 1 billion people in the developing world lack access to safe, reliable sources of drinking water. Unsafe water takes a toll not only on human health but also on individuals’ economic productivity. Illness from waterborne disease robs people of time and...

419

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...

420

Biopolymer-reinforced synthetic granular nanocomposites for affordable point-of-use water purification.  

PubMed

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

Sankar, Mohan Udhaya; Aig