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Sample records for freezing point depression

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

    NASA Astrophysics Data System (ADS)

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

    2002-01-01

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

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

    SciTech Connect

    Tanaka, Fumihiko; Murata, Satoshi; Habara, Kazuhiro; Amaratunga, K.S.P.

    1996-12-31

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

  3. The Freezing Point Depression Law in Physical Chemistry.

    ERIC Educational Resources Information Center

    Franzen, Hugo F.

    1988-01-01

    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)

  4. Measurement of Freezing Point Depression of Selected Food Solutions

    NASA Astrophysics Data System (ADS)

    Murata, Satoshi; Tanaka, Fumihiko; Matsuoka, Takahisa

    Freezing point depression of selected food solutions were measured at various concentrations in order to reveal the characteristics of solid-liquid phase equilibrium. The measurement were carried out on a hand made apparatus that was calibrated before the measurement by some of selected reagents (acid and sugar) with known thermal properties. The results revealed that the freezing point depression of selected food solutions deviated from the behavior of the ideal solution with increasing solute concentration, so the water activity for non-ideal solution were introduced to the freezing point depression equation. Further, assuming that the heat of fusion was a equation of temperature, thus the following new equation was led, ln {(1-Xs)/(l-Xs+α·Xs + β·Xs2)} = A(1/To - 1/Tf) - Bln(To/Tf) The goodness of fit of the equation showed the best results. Futhermore, by using the parameters a formula of freezing ratio and the relative water activities, which showed deviation from the ideal solution, were derived.

  5. Investigating Freezing Point Depression and Cirrus Cloud Nucleation Mechanisms Using a Differential Scanning Calorimeter

    ERIC Educational Resources Information Center

    Bodzewski, Kentaro Y.; Caylor, Ryan L.; Comstock, Ashley M.; Hadley, Austin T.; Imholt, Felisha M.; Kirwan, Kory D.; Oyama, Kira S.; Wise, Matthew E.

    2016-01-01

    A differential scanning calorimeter was used to study homogeneous nucleation of ice from micron-sized aqueous ammonium sulfate aerosol particles. It is important to understand the conditions at which these particles nucleate ice because of their connection to cirrus cloud formation. Additionally, the concept of freezing point depression, a topic…

  6. Oxygen demand of aircraft and airfield pavement deicers and alternative freezing point depressants

    USGS Publications Warehouse

    Corsi, Steven R.; Mericas, Dean; Bowman, George

    2012-01-01

    Aircraft and pavement deicing formulations and other potential freezing point depressants were tested for biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Propylene glycol-based aircraft deicers exhibited greater BOD5 than ethylene glycol-based aircraft deicers, and ethylene glycol-based products had lower degradation rates than propylene glycol-based products. Sodium formate pavement deicers had lower COD than acetate-based pavement deicers. The BOD and COD results for acetate-based pavement deicers (PDMs) were consistently lower than those for aircraft deicers, but degradation rates were greater in the acetate-based PDM than in aircraft deicers. In a 40-day testing of aircraft and pavement deicers, BOD results at 20°C (standard) were consistently greater than the results from 5°C (low) tests. The degree of difference between standard and low temperature BOD results varied among tested products. Freshwater BOD test results were not substantially different from marine water tests at 20°C, but glycols degraded slower in marine water than in fresh water for low temperature tests. Acetate-based products had greater percentage degradation than glycols at both temperatures. An additive component of the sodium formate pavement deicer exhibited toxicity to the microorganisms, so BOD testing did not work properly for this formulation. BOD testing of alternative freezing point depressants worked well for some, there was little response for some, and for others there was a lag in response while microorganisms acclimated to the freezing point depressant as a food source. Where the traditional BOD5 test performed adequately, values ranged from 251 to 1,580 g/kg. Where the modified test performed adequately, values of BOD28 ranged from 242 to 1,540 g/kg.

  7. Freezing Point Depression of Water in Phospholipid Membranes — A Solid-State NMR Study

    PubMed Central

    Lee, Dong-Kuk; Kwon, ByungSoo; Ramamoorthy, Ayyalusamy

    2009-01-01

    Lipid-water interaction plays an important role in the properties of lipid bilayers, cryoprotectants, and membrane-associated peptides and proteins. The temperature at which water bound to lipid bilayers freezes is lower than that of free water. Here, we report a solid-state NMR investigation on the freezing point depression of water in phospholipid bilayers in the presence and absence of cholesterol. Deuterium NMR spectra at different temperatures ranging from -75 to +10°C were obtained from fully 2H2O-hydrated POPC (1-palmitoyl-2-oleoyl-phosphatidylcholine) multilamellar vesicles (MLVs), prepared with and without cholesterol, to determine the freezing temperature of water and the effect of cholesterol on the freezing temperature of water in POPC bilayers. Our 2H NMR experiments reveal the motional behavior of unfrozen water molecules in POPC bilayers even at temperatures significantly below 0°C and show that the presence of cholesterol further lowered the freezing temperature of water in POPC bilayers. These results suggest that in the presence of cholesterol the fluidity and dynamics of lipid bilayers can be retained even at very low temperatures as exist in the liquid crystalline phase of the lipid. Therefore, bilayer samples prepared with a cryoprotectant like cholesterol should enable the performance of multidimensional solid-state NMR experiments to investigate the structure, dynamics, and topology of membrane proteins at a very low temperature with enhanced sample stability and possibly a better sensitivity. Phosphorus-31 NMR data suggest that lipid bilayers can be aligned at low temperatures, while 15N NMR experiments demonstrate that such aligned samples can be used to enhance the signal-to-noise ratio of 15N chemical shift spectra of a 37-residue human antimicrobial peptide, LL-37. PMID:18991419

  8. New expressions to describe solution nonideal osmotic pressure, freezing point depression, and vapor pressure.

    PubMed

    Fullerton, G D; Zimmerman, R J; Cantu, C; Cameron, I L

    1992-12-01

    New empirical expressions for osmotic pressure, freezing point depression, and vapor pressure are proposed based on the concepts of volume occupancy and (or) hydration force. These expressions are in general inverse relationships in comparison to the standard ideal expressions for the same properties. The slopes of the new equations are determined by the molecular weight of the solute and known constants. The accuracy and precision of the molecular weights calculated from the slope are identical and approximately 1% for the experiments reported here. The nonideality of all three colligative expressions is described by a dimensionless constant called the solute-solvent interaction parameter I. The results on sucrose have the same I = 0.26 for all three solution properties. The nonideality parameter I increased from 0.26 on sucrose to 1.7 on hemoglobin to successfully describe the well-known nonideal response of macromolecules. PMID:1299270

  9. Relationship of amino acid composition and molecular weight of antifreeze glycopeptides to non-colligative freezing point depression.

    PubMed

    Schrag, J D; O'Grady, S M; DeVries, A L

    1982-08-01

    Many polar fishes synthesize a group of eight glycopeptides that exhibit a non-colligative lowering of the freezing point of water. These glycopeptides range in molecular weight between 2600 and 33 700. The largest glycopeptides [1-5] lower the freezing point more than the small ones on a weight basis and contain only two amino acids, alanine and threonine, with the disaccharide galactose-N-acetyl-galactosamine attached to threonine. The small glycopeptides, 6, 7, and 8, also lower the freezing point and contain proline, which periodically substitutes for alanine. Glycopeptides with similar antifreeze properties isolated from the saffron cod and the Atlantic tomcod contain an additional amino acid, arginine, which substitutes for threonine in glycopeptide 6. In this study we address the question of whether differences in amino acid composition or molecular weight between large and small glycopeptides are responsible for the reduced freezing point depressing capability of the low molecular weight glycopeptides. The results indicate that the degree of amino acid substitutions that occur in glycopeptides 6-8 do not have a significant effect on the unusual freezing point lowering and that the observed decrease in freezing point depression with smaller glycopeptides can be accounted for on the basis of molecular weight. PMID:7115772

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

    SciTech Connect

    Hayashi, K.; Kasza, K.

    2000-05-03

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

  11. An evaluation of osmolality measurement by freezing point depression using micro-amounts of sample

    PubMed Central

    Koumantakis, G.; Wyndham, L. E.

    1989-01-01

    An evaluation of the Advanced micro-osmometer is presented. This instrument has been shown to have an excellent analytical precision (within-run CV = 0.59%, between-day CV = 0.58%). It is accurate over an analytical range of 0-2000 mmol/kg of osmolality shown by linearity studies and split sample correlations against vapour pressure osmometry, freezing point osmometry and an external quality assurance programme. Analytical errors due to operator technique are almost eliminated because of good instrument design. Preliminary results on whole-blood osmolality are included. The required sample size of 20 ?l permits osmolality measurements on most clinical samples. It is concluded that the Advanced micro-osmometer satisfies laboratory requirements. PMID:18925239

  12. Preliminary report on fluid inclusions from halites in the Castile and lower Salado formations of the Delaware Basin, southeastern New Mexico. [Freezing-point depression

    SciTech Connect

    Stein, C.L.

    1985-09-01

    A suite of samples composed primarily of halite from the upper Castile and lower Salado Formations of the Permian Basin was selected from Waste Isolation Pilot Plant (WIPP) core for a reconnaissance study of fluid inclusions. Volume percent of these trapped fluids averaged 0.7% to 1%. Freezing-point depressions varied widely and appeared to be unrelated to fluid-inclusion type, to sedimentary facies, or to stratigraphic depth. However, because very low freezing points were usually associated with anhydrite, a relation may exist between freezing-point data and lithology. Dissolved sulfate values were constant through the Castile, then decreased markedly with lesser depth in the lower Salado. This trend correlates very well with observed mineralogy and is consistent with an interpretation of the occurrence of secondary polyhalite as a result of gypsum or anhydrite alteration with simultaneous consumption of dissolved sulfate from the coexisting fluids. Together with the abundance and distribution of fluid inclusions in primary or ''hopper'' crystal structures, this evidence suggests that inclusions seen in these halites did not migrate any significant geographical distance since their formation. 28 refs., 17 figs., 2 tabs.

  13. Cold Heat Storage Characteristics of O/W-type Latent Heat Emulsion Including Continuum Phase of Water Treated with a Freezing Point Depression

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Morita, Shin-Ichi

    This paper deals with flow and cold heat storage characteristics of the oil (tetradecane, C14H30, freezing point 278.9 K, Latent heat 229 kJ/kg)/water emulsion as a latent heat storage material having a low melting point. The test emulsion includes a water-urea solution as a continuum phase. The freezing point depression of the continuum phase permits enhancement of the heat transfer rate of the emulison, due to the large temperature difference between the latent heat storage material and water-urea solution. The velocity of emulsion flow and the inlet temperature of coolant in a coiled double tube heat exchanger are chosen as the experimental parameters. The pressure drop, the heat transfer coefficient of the emulsion in the coiled tube are measured in the temperture region over solid and liquid phase of the latent heat storage material. The finishing time of the cold heat storage is defined experimentally in the range of sensible and latent heat storage. It is clarified that the flow behavior of the emulsion as a non-Newtonian fluid has an important role in cold heat storage. The useful nondimentional correlation equations for the additional pressure loss coefficient, the heat transfer coefficient and the finishing time of the cold heat storage are derived in terms of Dean number and heat capacity ratio.

  14. Device and method for determining freezing points

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, Balakrishnan (Inventor)

    1986-01-01

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

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

    ERIC Educational Resources Information Center

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

    2007-01-01

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

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

    ERIC Educational Resources Information Center

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

    2007-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Friedman, R.

    1979-01-01

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

  18. High freezing point fuels used for aviation turbine engines

    NASA Technical Reports Server (NTRS)

    Friedman, R.

    1979-01-01

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

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

    PubMed

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

    2009-07-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Pasion, A. J.

    1979-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, B.

    1982-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

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

    PubMed

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

    2014-04-01

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

  6. Nano materials for efficiently lowering the freezing point of heat transfer nanofluids

    NASA Astrophysics Data System (ADS)

    Hong, Haiping; Roy, Walter

    2007-09-01

    In this paper, we report, for the first time, the effect of the lowered freezing point in a 50% water / 50% antifreeze coolant (PAC) or 50% water / 50% ethylene glycol (EG) solution by the addition of carbon nanotubes and other particles. The experimental results indicated that the nano materials are much more efficient (hundreds fold) in lowering the freezing point than the regular ionic materials (e.g. NaCl). The possible explanation for this interesting phenomenon is the colligative property of fluid and relative small size of nano material. It is quite certain that the carbon nanotubes and metal oxide nano particles could be a wonderful candidate for the nano coolant application because they could not only increase the thermal conductivity, but also efficiently lower the freezing point of traditional coolants.

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

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, B.

    1984-01-01

    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.

  8. Origin of melting point depression for rare gas solids confined in carbon pores

    NASA Astrophysics Data System (ADS)

    Morishige, Kunimitsu; Kataoka, Takaaki

    2015-07-01

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ˜0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.

  9. Origin of melting point depression for rare gas solids confined in carbon pores

    SciTech Connect

    Morishige, Kunimitsu Kataoka, Takaaki

    2015-07-21

    To obtain insights into the mechanism of the melting-point depression of rare gas solids confined in crystalline carbon pores, we examined the freezing and melting behavior of Xe and Ar confined to the crystalline pores of ordered mesoporous carbons as well as compressed exfoliated graphite compared to the amorphous pores of ordered mesoporous silicas, by means of X-ray diffraction. For the Xe and Ar confined to the crystalline carbon pores, there was no appreciable thermal hysteresis between freezing and melting. Furthermore, the position of the main diffraction peak did not change appreciably on freezing and melting. This strongly suggests that the liquids confined in the carbon pores form a multilayered structure parallel to the smooth walls. For the Xe and Ar confined to the amorphous silica pores, on the other hand, the position of the main diffraction peak shifted into higher scattering angle on freezing suggested that the density of the confined solid is distinctly larger than for the confined liquid. Using compressed exfoliated graphite with carbon walls of higher crystallinity, we observed that three-dimensional (3D) microcrystals of Xe confined in the slit-shaped pores melted to leave the unmelted bilayers on the pore walls below the bulk triple point. The lattice spacing of the 3D microcrystals confined is larger by ∼0.7% than that of the bilayer next to the pore walls in the vicinity of the melting point.

  10. Dissemination of thermodynamic temperature above the freezing point of silver.

    PubMed

    Sadli, M; Machin, G; Anhalt, K; Bourson, F; Briaudeau, S; del Campo, D; Diril, A; Kozlova, O; Lowe, D H; Mantilla Amor, J M; Martin, M J; McEvoy, H C; Ojanen-Saloranta, M; Pehlivan, Ö; Rougié, B; Salim, S G R

    2016-03-28

    The mise-en-pratique for the definition of the kelvin at high temperatures will formally allow dissemination of thermodynamic temperature either directly or mediated through high-temperature fixed points (HTFPs). In this paper, these two distinct dissemination methods are evaluated, namely source-based and detector-based. This was achieved by performing two distinct dissemination trials: one based on HTFPs, the other based on absolutely calibrated radiation thermometers or filter radiometers. These trials involved six national metrology institutes in Europe in the frame of the European Metrology Research Programme joint project 'Implementing the new kelvin' (InK). The results have shown that both dissemination routes are possible, with similar standard uncertainties of 1-2 K, over the range 1273-2773 K, showing that, depending on the facilities available in the laboratory, it will soon be possible to disseminate thermodynamic temperatures above 1273 K to users by either of the two methods with uncertainties comparable to the current temperature scale. PMID:26903097

  11. Keeping gallium metal to liquid state under the freezing point by using silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Cao, Lingfei; Park, Hyunseo; Dodbiba, Gjergj; Ono, Kenji; Tokoro, Chiharu; Fujita, Toyohisa

    2011-10-01

    Gallium metal under the freezing point was observed to maintain its liquid state by dispersing silica nanoparticles of a given particle size and concentration. Though the freezing point of pure gallium is 302.9 K, the liquid gallium maintained its supercooling state at 276-277 K for more than 400 days by dispersing 1.0 wt. % of silica nanoparticles (10 nm in size). Extended x-ray absorption fine structure analysis shows that the supercooled gallium liquid has a β-Ga-like feature, and the nearest neighboring atom distance is 0.1 Å larger than that of pure liquid gallium. This method opens the way to use liquid gallium as a promising fluid carrier in energy conversion devices.

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

    PubMed Central

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

    1969-01-01

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

  13. Realization of tin freezing point using a loop heat pipe-based hydraulic temperature control technique

    NASA Astrophysics Data System (ADS)

    Joung, Wukchul; Gam, Kee Sool; Kim, Yong-Gyoo

    2015-10-01

    In this work, the freezing point of tin (Sn FP) was realized by inside nucleation where the supercooling of tin and the reheating of the sample after the nucleation were achieved without extracting the cell from an isothermal apparatus. To this end, a novel hydraulic temperature control technique, which was based on the thermo-hydraulic characteristics of a pressure-controlled loop heat pipe (LHP), was employed to provide a slow cooling of the sample for deep supercooling and fast reheating after nucleation to minimize the amount of initial freeze of the sample. The required temperature controls were achieved by the active pressure control of a control gas inside the compensation chamber of the pressure-controlled LHP, and slow cooling at  -0.05 K min-1 for the deep supercooling of tin and fast heating at 2 K min-1 for reheating the sample after nucleation was attained. Based on this hydraulic temperature control technique, the nucleation of tin was realized at supercooling of around 19 K, and a satisfactorily fast reheating of the sample to the plateau-producing temperature (i.e. 0.5 K below the Sn FP) was achieved without any temperature overshoots of the isothermal region. The inside-nucleated Sn FP showed many desirable features compared to the Sn FP realized by the conventional outside nucleation method. The longer freezing plateaus and the better immersion characteristics of the Sn FP were obtained by inside nucleation, and the measured freezing temperature of the inside-nucleated Sn FP was as much as 0.37 mK higher than the outside-nucleated Sn FP with an expanded uncertainty of 0.19 mK. Details on the experiment are provided and explanations for the observed differences are discussed.

  14. When hot water freezes before cold

    NASA Astrophysics Data System (ADS)

    Katz, J. I.

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  17. 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

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

    2013-09-11

    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.

  18. 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)

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

    2013-09-01

    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.

  19. Optimization of thermophysical properties of Pacific white shrimp (Litopenaeus vannamei) previously treated with freezing-point regulators using response surface methodology.

    PubMed

    Wang, Liang; Liu, Zunying; Zhao, Yuanhui; Dong, Shiyuan; Zeng, Mingyong; Yang, Huicheng

    2015-08-01

    Three freezing-point regulators (glycine, sodium chloride and D-sorbitol) were employed to optimize thermophysical properties of Pacific white shrimp (Litopenaeus vannamei) using response surface methodology (RSM). The independent variables were glycine content (0.250-1.250 %), sodium chloride content (0.500-2.500 %) and D-sorbitol content (0.125-0.625 %) and analysis of variance showed that the effects of glycine, sodium chloride and D-sorbitol on the thermophysical properties were statistically significant (P < 0.05). The coefficient of determination, R (2) values for initial freezing point (T i ), unfreezable water mass fraction (W u ), apparent specific heat (C app ) and Enthalpy (H) were 0.896 ~ 0.999. The combined effects of these independent variables on T i , W u , C app and H were investigated. The results indicated that T i , C app and H varied curvilinearly with increasing of glycine, sodium chloride and D-sorbitol content whereas W u increased nearly linearly. Based on response plots and desirability functions, the optimum combination of process variables for Pacific white shrimp previously treated with freezing-point regulators were 0.876 % for glycine content, 2.298 % for sodium chloride content and 0.589 % for D-sorbitol content, correspondently the optimized thermophysical properties were T i , - 5.086 °C; W u , 17.222 %; C app , 41.038 J/g °C and H, 155.942 J/g, respectively. Briefly, the application of freezing-point regulators depressed T i and obtained the optimum W u , C app and H, which would be obviously beneficial for the exploitation of various thermal processing and food storage. PMID:26243904

  20. Prospective Chemistry Teachers' Misconceptions about Colligative Properties: Boiling Point Elevation and Freezing Point Depression

    ERIC Educational Resources Information Center

    Pinarbasi, Tacettin; Sozbilir, Mustafa; Canpolat, Nurtac

    2009-01-01

    This study aimed at identifying prospective chemistry teachers' misconceptions of colligative properties. In order to fulfill this aim, a diagnostic test composed of four open-ended questions was used. The test was administered to seventy-eight prospective chemistry teachers just before qualifying to teaching in secondary schools. Nine different…

  1. Prospective Chemistry Teachers' Misconceptions about Colligative Properties: Boiling Point Elevation and Freezing Point Depression

    ERIC Educational Resources Information Center

    Pinarbasi, Tacettin; Sozbilir, Mustafa; Canpolat, Nurtac

    2009-01-01

    This study aimed at identifying prospective chemistry teachers' misconceptions of colligative properties. In order to fulfill this aim, a diagnostic test composed of four open-ended questions was used. The test was administered to seventy-eight prospective chemistry teachers just before qualifying to teaching in secondary schools. Nine different

  2. Graphene confinement effects on melting/freezing point and structure and dynamics behavior of water.

    PubMed

    Foroutan, Masumeh; Fatemi, S Mahmood; Shokouh, F

    2016-05-01

    In this work, the melting/freezing point of confined water between two graphene sheets was calculated from the direct coexistence of the solid-liquid interface. Also, molecular dynamics simulation of confined liquid water-ice between two graphene sheets was applied. The phase transition temperature of the confined ice-water mixture was calculated as 240K that was 29K less than the non-confined ice-water system. In order to study the behavior of water molecules at different distances from the graphene sheets, 5 regions were provided using some imaginary planes, located between two graphene sheets. The obtained simulation results showed that water molecules located in the region near each graphene sheet with the thickness of 2nm had a different behavior from other water molecules located in other regions. The results demonstrated that water molecules in the vicinity of graphene sheets had more mean square displacements than those in the middle regions. PMID:27041448

  3. Relationship Between Ice Nucleation Temperature Depression and Equilibrium Melting Points Depression of Medaka (Oryzias latipes) Embryos

    NASA Astrophysics Data System (ADS)

    Kimizuka, Norihito; Suzuki, Toru

    We measured the ice nucleation temperature depression , ΔTf , and equilibrium melting points depression, ΔTm, of Medaka (Oryzias latipes) embryos with different cryoprotectant (ethylene glycol, 1.3-propanediol, 1.4-butanediol, glycerol aqueous solutions) treatments. Our obtained results showed the good relationship between the ΔTf ,and ΔTm all samples. In addition the value of λ , which can be obtained from the linear relationship, ΔTf =λ ΔTm, were confirmed to show correlation with the value of λ , as obtained by the W/O emulsion method.

  4. Depression of melting point for protective aluminum oxide films

    NASA Astrophysics Data System (ADS)

    Dreizin, E. L.; Allen, D. J.; Glumac, N. G.

    2015-01-01

    The protective aluminum oxide film naturally formed on a surface of aluminum has a thickness in the range of 3-5 nm. Its melting causes loss of its continuity, which may significantly affect the ignition and combustion processes and their relative time scales. Melting of the alumina film also plays an important role when aluminum powders are used to prepare composites and/or being sintered. This letter quantifies depression of the melting point of an alumina film based on its nano-meter thickness. A theoretical estimate is supported by experiments relying on a detected change in the optical properties of naturally oxidized aluminum particles heated in an inert environment.

  5. A psychometric cut-point to separate emergently suicidal depressed patients from stable depressed outpatients

    PubMed Central

    McCall, W. Vaughn; Batson, Nicolas; Webster, Megan; Joshi, Indu; Derreberry, Todd; McDonough, Adam; Farris, Suzan

    2013-01-01

    Context: The design of safe clinical trials targeting suicidal ideation requires operational definitions of what degree of suicidal ideation is too excessive to allow safe participation. Aims: We examined the Scale for Suicide Ideation (SSI) to develop a psychometric cut-point that would identify patients having a suicidal emergency. Settings and Design: The Emergency Department (ED) and the out-patient clinic of a university hospital. Materials and Methods: We used the SSI to contrast 23 stable, depressed adult out-patients versus 11 depressed adult ED patients awaiting psychiatric admission for a suicidal emergency. Statistical Analysis: The performance of the SSI was examined with nominal logistic regression. Results: ED patients were older than out-patients (P<0.001), with proportionally more men (P<0.05), and were more ethnically diverse than the outpatients (P<0.005). Compared to out-patients, ED patients were more depressed (Patient Health Questionnaire-9 score 23.13.8 vs. 11.77.3, P<0.005) and reported a greater degree of suicidal ideation (SSI scores 25.77.3 vs. 4.28.4, P<0.0001). Nominal logistic regression for the univariate model of SSI score and group yielded a score of 16 (P<0.0001) as the best cut-point in separating groups, with a corresponding Receiver Operating Characteristic Area Under the Curve = 0.94. Of 34 patients in the total sample, only two were misclassified by SSI score = 16, with both of these being false positive for ED status. Thus, the sensitivity of the cut-point was 100% with specificity of 91%. When the model was expanded to include SSI along with age, gender, ethnicity, sedative-hypnotic use, and over-the-counter use, only SSI score remained significant as a predictor. Conclusions: A SSI score ?16 may be useful as an exclusion criterion for out-patients in depression clinical trials. PMID:24082251

  6. 'Love Hormone' Levels in Pregnancy May Point to Risk for Postpartum Depression

    MedlinePlus

    ... in Pregnancy May Point to Risk for Postpartum Depression Goal is to identify and treat this mental ... may be associated with increased risk of postpartum depression in some women, researchers say. The findings suggest ...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    SciTech Connect

    Wang, J.; Apte, Pankaj; Morris, James R; Zeng, X.C.

    2013-01-01

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

  9. Freezing points and small-scale deicing tests for salts of levulinic acid made from grain sorghum.

    PubMed

    Ganjyal, G; Fang, Q; Hanna, M A

    2007-11-01

    Deicers from renewable resources are needed to overcome the disadvantages of using traditional deicers. Salts made from levulinic acid produced using grain sorghum as raw material were tested as road deicing agents. Freezing points of these salts viz., sodium levulinate, magnesium levulinate and calcium levulinate along with rock salt (sodium chloride) were determined according to American Society for Testing and Materials (ASTM) D 1177-94 standard at concentrations of 10, 20, 30 and 40 % w/w. There were significant differences among the freezing points of the salts. Freezing points for rock salt, sodium levulinate, calcium levulinate and magnesium levulinate, for different concentrations, were in the ranges of -6.6 to -20.5, -2.9 to -15.0, -2.1 to -7.8 and -1.5 to -6.5 degrees C, respectively. Deicing effectiveness of the salts of levulinic acid were investigated by conducting small-scale deicing tests with aqueous solutions of various salt concentrations (2%, 5% and 10%) in a laboratory freezer and by spraying the deicer on a graveled surface covered by ice and snow with the average temperature during the testing at -2.7 degrees C. Deicing capabilities of the three salts of levulinic acid differed. At -2.7 degrees C, all three salts caused melting of the ice. Among the different levulinates studied sodium levulinate was the most effective deicing agent. These salts of levulinates could be a viable replacement for traditional deicers and could help in reducing the disadvantages of traditional deicers. PMID:17416518

  10. Working and Non-Working University Students: Anxiety, Depression, and Grade Point Average

    ERIC Educational Resources Information Center

    Mounsey, Rebecca; Vandehey, Michael A.; Diekhoff, George M.

    2013-01-01

    This study explored the differences between 110 working and non-working students in terms of mental health, academic achievement, and perceptions about student employment. Anxiety and depression were measured by the Beck Anxiety Inventory and the Beck Depression Inventory-II. Academic achievement was measured by grade point average. Perceptions of…

  11. Working and Non-Working University Students: Anxiety, Depression, and Grade Point Average

    ERIC Educational Resources Information Center

    Mounsey, Rebecca; Vandehey, Michael A.; Diekhoff, George M.

    2013-01-01

    This study explored the differences between 110 working and non-working students in terms of mental health, academic achievement, and perceptions about student employment. Anxiety and depression were measured by the Beck Anxiety Inventory and the Beck Depression Inventory-II. Academic achievement was measured by grade point average. Perceptions of

  12. Freezing Models For Heterogeneous Drop Freezing In Immersion and Contact Modes

    NASA Astrophysics Data System (ADS)

    Diehl, K.; Wurzler, S.

    Field measurements showed that supercooled liquid water drops and frozen drops can coexist in tropospheric clouds at temperatures down to -40 C with an incidence of ice particles already at -4 C. The freezing behaviour of water drops depends on their sizes, on their content of soluble particles (freezing point depression) and of insoluble particles (potential immersion ice nuclei) as well as on the collision with dry particles (potential contact ice nuclei). In the present model studies, the influence of soluble and insoluble particles on drop freezing in immersion and contact modes are considered. Using a two dimensional field of drop and aerosol particle sizes the numerical simula- tion of the coexistence of similar sized drops with different compositions is possible, also the combination of different collision partners. The freezing point depression of salt solution drops was calculated according to physical chemistry equations. The median freezing temperatures of particles in the immersion and contact modes were derived from laboratory results for typical atmospheric ice nuclei. The collision effi- ciency was calculated based on experimental results and numerical estimations. The results obtained with the freezing models are consistent with experimental results. They show that in the whole temperature range relevant for the troposphere the com- position of the drops has an important influence on their freezing in the immersion mode. The smaller the drop sizes, the more effecting are the soluble particles. A sig- nificant influence of insoluble immersion ice nuclei on atmospheric drop f reezing can be expected at temperatures of -20 C and lower, in the contact freezing mode already at temperatures around -10 C, with the different insoluble particles not showing large deviations. However, the freezing efficiency of contact ice nuclei is restricted by the collision efficiency which is dependant on both, the drop and aerosol particle size.

  13. High-speed Imaging of Freezing Drops: Investigating the Role of Point-like Contact in Heterogeneous Ice Nucleation

    NASA Astrophysics Data System (ADS)

    Gurganus, C.; Charnawskas, J.; Shaw, R. A.; Kostinski, A. B.

    2013-12-01

    Formation of ice by contact nucleation remains enigmatic and the possible role of the three-phase boundary (i.e., liquid water-ice-aerosol contact line) is still undetermined. Because aerosol size, surface area, composition and exact region of contact remain difficult to measure, we examine a simpler geometry with a spherical cap droplet resting on a substrate. In this configuration, the droplet simultaneously experiences a two-phase immersion region and a three phase contact region around the perimeter of the droplet. Utilizing high speed imaging of the droplet-substrate plane, we are able to identify nucleation sites in individual droplets. This technique allows for a spatial distribution of freezing sites in addition to a freezing temperature distribution. Our initial study indicated no preference for nucleation originating at the three phase boundary for an atomically smooth homogenous substrate [1]. The nucleation site distribution agreed well with the stochastic view in that the germ sites are distributed uniformly over the surface area. In that study we minimized the thermal variation (?T) across a droplet during cooling to prevent biased observations. We also compared ?T for several experiments in literature using a simple formulation of droplet size (r) and cooling rate (?). Large variations in some experiments could possibly explain observed 'contact nucleation' events in the laboratory as artifacts of radial thermal variations during droplet cooling. As a continuation of this study, we redesigned our system to enable much greater substrate cooling rates, but these experiments too revealed no preference for nucleation in the contact mode. Thermal modeling of the new system confirmed that while a vertical thermal gradient does develop within the droplet, no horizontal gradient is induced in the drop near the substrate. This result argues against a thermodynamic bias toward contact nucleation in substrate cooled geometries. Another possible explanation for this contact phenomenon comes in a lowering of the energy barrier for nucleation due to the existence of a line tension at the point of contact. A scale analysis of the line and surface energy values available in the literature suggests that line tension may become dominant below length scales of ~10 nm [1]. From this simple result we postulate that 'point-like' surface features might play an important role at the three phase boundary. To mimic these features on substrates we introduce chemical and mechanical processes to enhance substrate surface roughness. Using these new substrates we repeat our experimental procedure to compare effectiveness of the immersion (two phase) and contact (three phase) regions for a variety of surface topologies. Here we report the initial findings from this work. 1. Gurganus, C.; Kostinski, A. B.; Shaw, R. A., Fast Imaging of Freezing Drops: No Preference for Nucleation at the Contact Line. J Phys Chem Lett 2011, 2 (12) Identifying nucleation sites with two high speed cameras.

  14. Detecting Critical Decision Points in Psychotherapy and Psychotherapy + Medication for Chronic Depression

    PubMed Central

    Steidtmann, Dana; Manber, Rachel; Blasey, Christine; Markowitz, John C.; Klein, Daniel N.; Rothbaum, Barbara O.; Thase, Michael E.; Kocsis, James H.; Arnow, Bruce A.

    2014-01-01

    Objective To quantify clinical decision points for identifying depression treatment non-remitters prior to end-of-treatment. Method Data come from the psychotherapy arms of a randomized clinical trial for chronic depression. Participants (n=352; 65.6% female; 92.3% White; mean age = 44.3 years) received 12 weeks of Cognitive Behavioral Analysis System of Psychotherapy (CBASP) or CBASP plus an antidepressant medication. In half of the sample, receiver operating curve (ROC) analyses were used to identify efficient percent symptom reduction cut points on the Inventory of Depressive Symptoms-Self Report (IDS-SR) for predicting end-of-treatment nonremission based on the Hamilton Rating Scale for Depression (HRSD). Sensitivity, specificity, predictive values and Cohen’s kappa for identified cut points were calculated using the remaining half of the sample. Results Percent IDS-SR symptom reduction at weeks 6 and 8 predicted end of treatment HRSD remission status in both the combined treatment (week 6 cut point = 50.0%, Cohen’s kappa = .42; week 8 cut point = 54.3%, Cohen’s kappa = .45), and psychotherapy only (week 6 cut point = 60.7%, Cohen’s kappa = .41; week 8 cut point = 48.7%, Cohen’s kappa = .49). Week 8 was more reliable for identifying nonremitters in psychotherapy only treatment. Conclusions Those with chronic depression who will not remit in structured, time-limited psychotherapy for depression, either alone or in combination with antidepressant medication, are identifiable prior to end-of-treatment. Findings provide an operationalized strategy for designing adaptive psychotherapy interventions. PMID:23750462

  15. Activity coefficients and free energies of nonionic mixed surfactant solutions from vapor-pressure and freezing-point osmometry.

    PubMed

    MacNeil, Jennifer A; Ray, Gargi Basu; Leaist, Derek G

    2011-05-19

    The thermodynamic properties of mixed surfactant solutions are widely investigated, prompted by numerous practical applications of these systems and by interest in molecular association and self-organization. General techniques for measuring thermodynamic activities, such as isopiestic equilibration, are well-established for multicomponent solutions. Surprisingly, these techniques have not yet been applied to mixed surfactant solutions, despite the importance of the free energy for micelle stability. In this study, equations are developed for the osmotic coefficients of solutions of nonionic surfactant A + nonionic surfactant B. A mass-action model is used, with virial equations for the activity coefficients of the micelles and free surfactant monomer species. The equations are fitted to osmotic coefficients of aqueous decylsulfobetaine + dodecylsulfobetaine solutions measured by vapor-pressure and freezing-point osmometry. Equilibrium constants for mixed-micelle formation are calculated from the free monomer concentrations at the critical micelle concentrations. The derived activity coefficients of the micelles and free monomers indicate large departures from ideal solution behavior, even for dilute solutions of the surfactants. Stoichiometric activity coefficients of the total surfactant components are evaluated by Gibbs-Duhem integration of the osmotic coefficients. Relatively simple colligative property measurements hold considerable promise for free energy studies of multicomponent surfactant solutions. PMID:21504169

  16. Depression

    MedlinePlus

    ... Stay Connected Home » Depression Heath and Aging Depression What Causes Depression? What to Look For Getting ... feel better with the right treatment. What Causes Depression? There is no one cause of depression. For ...

  17. Depression Treatment for Impoverished Mothers by Point-of-Care Providers: A Randomized Controlled Trial

    PubMed Central

    Segre, Lisa S.; Brock, Rebecca L.; O’Hara, Michael W.

    2015-01-01

    Objective Depression in low-income, ethnic-minority women of childbearing age is prevalent and compromises infant and child development. Yet numerous barriers prevent treatment delivery. Listening Visits (LV), an empirically supported intervention developed for delivery by British home-visiting nurses, could address this unmet mental health need. This randomized controlled trial evaluated the effectiveness of LV delivered at a woman’s usual point-of-care, including home-visits or an ob-gyn office. Method Listening Visits were delivered to depressed pregnant women or mothers of young children by their point-of-care provider (e.g., home visitor or physician’s assistant), all of whom had low levels of prior counseling experience. Three quarters of the study’s participants were low-income. Of those who reported ethnicity, all identified themselves as minorities. Participants from four study sites (N = 66) were randomized in a 2:1 ratio, to LV or a wait-list control group (WLC). Assessments, conducted at baseline and 8 weeks, evaluated depression, quality of life, and treatment satisfaction. Results Depressive severity, depressive symptoms, and quality of life significantly improved among LV recipients as compared to women receiving standard social/health services. Women valued LV as evidenced by their high attendance rates and treatment satisfaction ratings. Conclusions In a stepped model of depression care, LV can provide an accessible, acceptable, and effective first-line treatment option for at-risk women who otherwise are unlikely to receive treatment. PMID:25486371

  18. Freezing in confined geometries

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  19. Periodic ice banding in freezing colloidal dispersions.

    PubMed

    Anderson, Anthony M; Worster, M Grae

    2012-12-01

    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

  20. Negative pressures and melting point depression in oxide-coated liquid metal droplets

    NASA Technical Reports Server (NTRS)

    Spaepen, F.; Turnbull, D.

    1979-01-01

    Negative pressures and melting point depression in oxide-coated liquid metal droplets are studied. The calculation presented show the existence of large negative pressures when the oxide coating is thick enough. The change in the melting point caused by these negative pressures should be considered in studies of homogeneous crystal nucleation. Furthermore, since the negative pressure raises the entropy of the melt, it increases the entropy loss at the crystal-melt interface; the resulting increase of the surface tension could have a large effect on the homogeneous nucleation frequency.

  1. Depression

    MedlinePlus

    ... or digestive problems Thoughts of death or suicide Depression is a disorder of the brain. There are a variety of causes, including genetic, biological, environmental, and psychological factors. Depression ...

  2. Depression

    MedlinePlus

    ... realize it yet, but she is depressed. Regular Sadness vs. Depression Feeling sad, down, or discouraged are ... close can lead to a specific kind of sadness — grief. Most of the time, people manage to ...

  3. Depression

    MedlinePlus

    ... rate. Women with depression typically have symptoms of sadness, worthlessness, and guilt. Men with depression are more ... be less likely to admit to feelings of sadness or grief. They also are more likely to ...

  4. Depression

    MedlinePlus

    ... to enjoy (including sex) Thinking about death or suicide Physical symptoms Changes in appetite (eating more than ... help prevent depression from coming back. Thoughts of suicide are common in people with depression. The risk ...

  5. Magneto-caloric effect of a Gd50Co50 amorphous alloy near the freezing point of water

    NASA Astrophysics Data System (ADS)

    Xia, L.; Wu, C.; Chen, S. H.; Chan, K. C.

    2015-09-01

    In the present work, we report the magneto-caloric effect (MCE) of a binary Gd50Co50 amorphous alloy near the freezing temperature of water. The Curie temperature of Gd50Co50 amorphous ribbons is about 267.5 K, which is very close to room temperature. The peak value of the magnetic entropy change (-ΔSmpeak) and the resulting adiabatic temperature rise (ΔTad.) of the Gd50Co50 amorphous ribbons is much higher than that of any other amorphous alloys previously reported with a Tc near room temperature. On the other hand, although the -ΔSmpeak of Gd50Co50 amorphous ribbons is not as high as those of crystalline alloys near room temperature, its refrigeration capacity (RC) is still much larger than the RC values of these crystalline alloys. The binary Gd50Co50 amorphous alloy provides a basic alloy for developing high performance multi-component amorphous alloys near room temperature.

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

    NASA Technical Reports Server (NTRS)

    Albright, A. E.

    1984-01-01

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

  7. Final report on COOMET.T-S1. Comparison of type S thermocouples at the freezing points of zinc, aluminium and copper 2014—2015

    NASA Astrophysics Data System (ADS)

    Pokhodun, A. I.; Ivanova, A. G.; Duysebayeva, K. K.; Ivanova, K. P.

    2015-01-01

    Regional comparison of type S thermocouples at the freezing points of zinc, aluminium and copper was initiated by COOMET TC1.1-10 (the technical committee of COOMET `Thermometry and thermal physics'). Three NMI take part in COOMET regional comparison: D I Mendeleev Institute for Metrology (VNIIM) (Russian Federation), National Scientific Centre (Institute of Metrology) (NSC IM, Ukraine), Republic State Enterprise (Kazakhstan Institute of Metrology) (KazInMetr, Republic of Kazakhstan). VNIIM (Russia) was chosen as the coordinator-pilot of the regional comparison. A star type comparison was used. The participants: KazInMetr and NSC IM constructed the type S thermocouples and calibrated them in three fixed points: zinc, aluminum and copper points, using methods of ITS-90 fixed point realizations. The thermocouples have been sent to VNIIM together with the results of the calibration at three fixed points, with the values of the inhomogeneity at temperature 200 °C and the uncertainty evaluations of the results. For calibration of thermocouples the same VNIIM fixed points cells were used. Participating laboratories repeated the calibration of thermocouples after its returning in zinc, aluminum and copper points to determine the stability of its results. In result of the comparison was to evaluate the equivalence of the type S thermocouples calibration in fixed points by NMIs to confirm corresponding lines of international website for NMI's Calibration and Measurement Capabilities (CMC). This paper is the final report of the comparison including analysis of the uncertainty of measurement results. 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 WG-KC, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  8. Depression.

    ERIC Educational Resources Information Center

    Strock, Margaret

    Approximately ten percent of the population suffers from a depressive illness each year. Although the economic cost is high, the cost in human suffering is immeasurable. To help educate the population about this disorder, this paper presents a definition of depression and its common manifestations. The symptoms that people often experience are…

  9. Method and apparatus for determining the presence or absence of a pour point depressant additive in hydrocarbon liquids

    SciTech Connect

    Rummel, J.D.

    1986-07-29

    A method is described of determining the presence or absence of a pour point depressant additive in a hydrocarbon liquid derived from petroleum, the liquid containing paraffin wax, comprising the steps of: (a) cooling a sample of the liquid at a predetermined cooling rate from a temperature substantially above the cloud point temperature to a temperature substantially below the cloud point temperature; (b) monitoring the slope of the cooling rate curve and noting the points at which a deflection in the curve begins and ends; (c) determining the time interval between the beginning and ending points of the deflection of the curve, and (d) comparing the determined time interval to a reference time interval, associated with the predetermined cooling rate, so as to establish whether the determined time interval is less than or greater than the reference time interval thereby establishing the presence or absence, respectively, of a pour point depressant additive.

  10. Depression.

    PubMed

    Weissman, Myrna

    2009-04-01

    This is an invited article on how my career as an epidemiologist studying depression unfolded. The role of the Civil Rights movement in opening the PhD doors to women at Yale began my career. The unfolding of depression studies are described. These studies included a clinical trial of medication and what later was known as interpersonal psychotherapy (IPT), the first community survey of psychiatric disorder, family genetic and brain imaging studies or depression and anxiety disorders. I hope the new generation will have the wonderful opportunities I have had. PMID:19344866

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

    PubMed

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

    2013-01-01

    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

  12. Depressants

    MedlinePlus

    ... and other mental health issues continue Other Possible Problems Taking too much of a depressant at once ... stop taking the drugs can have tremors, breathing problems, and seizures, go into a coma, or even ...

  13. Freeze-fracture cytochemistry: replicas of critical point-dried cells and tissues after fracture-label.

    PubMed

    da Silva, P P; Kachar, B; Torrisi, M R; Brown, C; Parkison, C

    1981-07-10

    Applications of the new fracture-labeling techniques for the observation of cytochemical labels on platinum-carbon replicas are described. Frozen cells, embedded in a cross-linked protein matrix, and frozen tissues are fractured with a scalpel under liquid nitrogen, thawed, labeled, dehydrated by the critical point drying method, and replicated. This method allows direct, high-resolution, two-dimensional chemical and immunological characterization of the cellular membranes in situ, as well as detection of sites within cross-fractured cytoplasm and extracellular matrix. PMID:7244630

  14. Poly(vinyl methyl ether) hydrogels at temperatures below the freezing point of water-molecular interactions and states of water.

    PubMed

    Pastorczak, Marcin; Dominguez-Espinosa, Gustavo; Okrasa, Lidia; Pyda, Marek; Kozanecki, Marcin; Kadlubowski, Slawomir; Rosiak, Janusz M; Ulanski, Jacek

    2014-01-01

    Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water. That kind of water is particularly well observable at temperatures below the freezing point of water, when the bulk water crystallizes. In this work, we determine the amount of water bound to the polymer and of the so-called pre-melting water in poly(vinyl methyl ether) hydrogels with the use of Raman spectroscopy, dielectric spectroscopy, and calorimetry. This analysis allows us to compare various physical properties of the bulk and the pre-melting water. We also postulate the molecular mechanism responsible for the pre-melting of part of water in poly(vinyl methyl ether) hydrogels. We suggest that above -60 °C, the first segmental motions of the polymer chain are activated, which trigger the process of the pre-melting. PMID:25100897

  15. On laboratory simulation and the effect of small temperature oscillations about the freezing point and ice formation on the evaporation rate of water on Mars.

    PubMed

    Moore, Shauntae R; Sears, Derek W G

    2006-08-01

    We report measurements of the evaporation rate of water under Mars-like conditions (CO2 atmosphere at 7 mbar and approximately 0 degrees C) in which small temperature oscillations about the freezing point repeatedly formed and removed a thin layer of ice. We found that the average evaporation at 2.7 +/- 0.5 degrees C without an ice layer (corrected for the difference in gravity on Earth and on Mars) was 1.24 +/- 0.12 mm/h, while at -2.1 +/- 0.3 degrees C with an ice layer the average evaporation rate was 0.84 +/- 0.08 mm/h. These values are in good agreement with those calculated for the evaporation of liquid water and ice when it is assumed that evaporation only depends on diffusion and buoyancy. Our findings suggest that such differences in evaporation rates are entirely due to the temperature difference and that the ice layer has little effect on evaporation rate. We infer that the formation of thin layers of ice on pools of water on Mars does not significantly increase the stability of water on the surface of Mars. PMID:16916288

  16. Exposure to early adversity: Points of cross-species translation that can lead to improved understanding of depression.

    PubMed

    Andersen, Susan L

    2015-05-01

    The relationship between developmental exposure to adversity and affective disorders is reviewed. Adversity discussed herein includes physical and sexual abuse, neglect, or loss of a caregiver in humans. While these stressors can occur at any point during development, the unique temporal relationship to specific depressive symptoms was the focus of discussion. Further influences of stress exposure during sensitive periods can vary by gender and duration of abuse as well. Data from animal studies are presented to provide greater translational and causal understanding of how sensitive periods, different types of psychosocial stressors, and sex interact to produce depressive-like behaviors. Findings from maternal separation, isolation rearing, chronic variable stress, and peer-peer rearing paradigms clarify interpretation about how various depressive behaviors are influenced by age of exposure. Depressive behaviors are broken down into the following categories: mood and affect, anhedonia, energy, working memory, sleep-wake, appetite changes, suicide, and general malaise. Cross-species evidence from humans, nonhuman primates, rats, and mice within each of these categories is discussed. In conclusion, sensitive periods for affective-related behaviors (anxiety, mood, and controllability) occur earlier in life, while other aspects of depression are associated with adversity later during adolescence. PMID:25997766

  17. MedLink: A Mobile Intervention to Address Failure Points in the Treatment of Depression in General Medicine

    PubMed Central

    Mohr, David C.; Stiles-Shields, Colleen; Brenner, Christopher; Palac, Hannah; Montague, Enid; Kaiser, Susan M.; Carty-Fickes, Eric; Duffecy, Jenna

    2015-01-01

    Major depression is common, and imposes a high burden in terms of cost, morbidity, and suffering. Most people with depression are treated in general medicine using antidepressant medication. Outcomes are poor due to failure points across the care system, including patient non-adherence, failure of physicians to optimize the treatment regimens, and lack of patient-physician communication. This study reports on the 4-week pilot deployment of MedLink, a mobile intervention aimed at systemically addressing each of these failure points. A mobile app provides the patient with information and collects data on symptoms and side-effects. A cellularly enabled pill bottle monitors medication adherence. Data from these are provided to the physician and patient to foster communication and medication adjustments. Usability evaluation was generally favorable. Medication adherence rates in this first deployment were high with no patients discontinuing, and 84% of doses taken. Depressive symptom severity was significantly reduced. This study supports the use of a comprehensive, systemic approach to mHealth solutions to enhance processes of care for depression by general medicine physicians. PMID:26640740

  18. Pore structure of hydrating cement paste by magnetic resonance relaxation analysis and freezing.

    PubMed

    Jehng, J Y; Sprague, D T; Halperin, W P

    1996-01-01

    Nuclear magnetic resonance relaxation analysis has been applied to interpret the evolution of microstructure in a cement paste during hydration. A basic understanding of the wet-dry and freeze-thaw processes of cement pastes has been developed. The pore structure evolution has been studied by the suppression of the freezing temperature of water and compared with spin-spin relaxation analysis performed at room temperature. Both methods consistently show that hydrating cement pastes have two principal components in their size distribution. The NMR relaxation times provide a measure of the characteristic pore sizes. Their interpretation is made in the context of a fast exchange model. Supercooling and thawing point depression of confined water has been studied systematically. The depression of the freezing point of liquid water confined within a pore was found to be dependent on the pore size, with capillary pore water freezing at 240 K and the remaining gel pore water freezing over a temperature range extending to as low as 160 K.A modified Gibbs-Thompson analysis was used to determine pore volume distributions from the distribution of thawing temperatures. PMID:8970082

  19. Immobilization and melting point depression of imidazolium ionic liquids on the surface of nano-SiOx particles.

    PubMed

    Liu, Yusheng; Wu, Guozhong; Fu, Haiying; Jiang, Zheng; Chen, Shimou; Sha, Maolin

    2010-04-01

    Four kinds of imidazolium-based ionic liquids (ILs) were immobilized onto the surface of nano-SiO(x) particles (d approximately 20 nm) by grinding in an agate mortar to produce a series of weight ratios of ionic liquid to nanoparticles. The physicochemical properties of immobilized ILs were investigated by differential scanning calorimetry, powder X-ray diffraction and Raman spectroscopy. It was found that the melting points (T(m)) of the immobilized ILs depressed significantly in comparison with the bulk ionic liquids. The T(m) depressions are 10, 12, 13 and 41 degrees C for [EMIM][PF(6)], [PMIM][PF(6)], [PHMIM][BF(4)] and [EMIM][I], respectively, for a loading amount of 35 wt% ionic liquid. The T(m) depression of [EMIM][PF(6)] was independent of the weight proportion of immobilized ionic liquid up to 50 wt%, indicating that nano-SiO(x) has a large capacity for immobilized ILs. The T(m) depression of [EMIM][I] is particularly significant because the H-bonding interactions of iodine anions with surface silanol groups of nano-SiO(x) particles is much weaker than that of fluorine anions with silanol groups of other investigated ionic liquids. PMID:20449446

  20. Satellite freeze forecast system

    NASA Technical Reports Server (NTRS)

    Martsolf, J. D. (Principal Investigator)

    1983-01-01

    Provisions for back-up operations for the satellite freeze forecast system are discussed including software and hardware maintenance and DS/1000-1V linkage; troubleshooting; and digitized radar usage. The documentation developed; dissemination of data products via television and the IFAS computer network; data base management; predictive models; the installation of and progress towards the operational status of key stations; and digital data acquisition are also considered. The d addition of dew point temperature into the P-model is outlined.

  1. Autobiographical Memory and Depression in the Later Age: The Bump Is a Turning Point

    ERIC Educational Resources Information Center

    Gidron, Yori; Alon, Shirly

    2007-01-01

    This preliminary study integrated previous findings of the distribution of autobiographical memories in the later age according to their age of occurrence, with the overgeneral memory bias predictive of depression. Twenty-five non-demented, Israeli participants between 65-89 years of age provided autobiographical memories to 4 groups of word cues…

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

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2010-01-01

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

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

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2010-01-01

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

  4. Entropy, Disorder, and Freezing

    NASA Astrophysics Data System (ADS)

    Laird, Brian B.

    1999-10-01

    It is argued that the usual view that entropy is a measure of "disorder" is problematic and that there exist systems at high density, for which packing considerations dominate, where a spatially ordered state has a higher entropy than a disordered one. A classic example is a system of hard-sphere atoms, for which freezing is known to be purely entropy driven. Such a model has relevance to the real world, since it provides a good qualitative (and nearly quantitative) description of solid-liquid coexistence in simple systems such as argon. An analogy based on the packing of suitcases is given to illustrate the main point. A simple classroom demonstration is also described in which an analog simulation of the freezing of hard particles is performed.

  5. New freeze pipe systems for nitrogen freezing

    NASA Astrophysics Data System (ADS)

    Rephan, D.

    A number of field and laboratory experiments have been carried out using new kinds of freezing pipe systems. These systems particularly enable freezing to be performed in stages. They further enable liquid gas consumption to be minimized. One system is particularly suitable for shaft freezing while another lends itself to tunnelling.

  6. Liquidus Temperature Depression in Cryolitic Melts

    NASA Astrophysics Data System (ADS)

    Solheim, Asbjørn

    2012-08-01

    The electrolyte in Hall-Héroult cells for the manufacture of primary aluminum nominally contains only cryolite (Na3AlF6) with additions of AlF3, CaF2, and Al2O3. However, impurities are present, entering the process with the feedstock. The effect on the liquidus temperature by the impurities cannot be calculated correctly by the well-known equation for freezing-point depression in binary systems simply because the electrolyte cannot be regarded as a binary system. By extending the equation for freezing-point depression to the ternary system NaF-AlF3-B, it appeared that the acidity of the impurity B plays a major role. Some calculations were made using an ideal Temkin model, and for most types of impurities, the effect on the liquidus temperature will be larger in an industrial electrolyte than what can be estimated from the equation for freezing-point depression in cryolite. Experimental data on the liquidus temperature in the system Na3AlF6-AlF3-Al2O3-CaF2-MgF2 show that the effect of MgF2 on the liquidus temperature increases strongly with decreasing NaF/AlF3 molar ratio, and it is suggested that MgF2 forms an anion complex, probably MgF{4/2-}.

  7. Preservation of flavor in freeze dried green beans

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  8. Narrow depression in the density of states at the Dirac point in disordered graphene

    NASA Astrophysics Data System (ADS)

    Schweitzer, L.

    2009-12-01

    The electronic properties of noninteracting particles moving on a two-dimensional bricklayer lattice are investigated numerically. In particular, the influence of disorder in form of a spatially varying random magnetic flux is studied. In addition, a strong perpendicular constant magnetic field B is considered. The density of states ρ(E) goes to zero for E→0 as in the ordered system but with a much steeper slope. This happens for both cases: at the Dirac point for B=0 and at the center of the central Landau band for finite B . Close to the Dirac point, the dependence of ρ(E) on the system size, on the disorder strength, and on the constant magnetic flux density is analyzed and fitted to an analytical expression proposed previously in connection with the thermal quantum-Hall effect. Additional short-range on-site disorder completely replenishes the indentation in the density of states at the Dirac point.

  9. Poromechanics of freezing materials

    NASA Astrophysics Data System (ADS)

    Coussy, Olivier

    2005-08-01

    When subjected to a uniform cooling below the freezing point a water-infiltrated porous material undergoes a cryo-deformation resulting from various combined actions: (i) the difference of density between the liquid water and the ice crystal, which results in the initial build-up of an in-pore pressure at the onset of crystallization; (ii) the interfacial effects arising between the different constituents, which eventually govern the crystallization process in connection with the pore access radius distribution; (iii) the drainage of the liquid water expelled from the freezing sites towards the air voids; (iv) the cryo-suction process, which drives liquid water towards the already frozen pores as the temperature further decreases; (v) the thermomechanical coupling between the solid matrix, the liquid water and the ice crystal. We work out a comprehensive theory able to encompass this whole set of actions. A macroscopic approach first provides the constitutive equations of freezing poroelastic materials, including the interfacial energy effects. This approach reveals the existence of a thermodynamic state function—namely the liquid saturation degree as a function of the temperature only. The macroscopic ice-dependent poroelastic properties are then upscaled from the knowledge of the elastic properties of the solid matrix, of the pore access radius distribution, and of the capillary curve. The theory is finally illustrated by analysing quantitatively the effects of the cooling rate and of the pore radius distribution upon the cryo-deformation of water-infiltrated porous materials. The theory succeeds in accounting for the experimentally observed shrinkage of embedded air voids, while predicting the partial melting of the ice already formed when the cooling suddenly stops.

  10. Freezing and Food Safety

    MedlinePlus

    ... Forms FSIS United States Department of Agriculture Food Safety and Inspection Service About FSIS District Offices Careers ... JSR 286) Actions ${title} Loading... Freezing and Food Safety What Can You Freeze? Is Frozen Food Safe? ...

  11. Fundamentals of freeze-drying.

    PubMed

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

    2002-01-01

    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 mobility, particularly at temperatures below the glass transition, be studied in greater depth. The relevance of the concept of strong and fragile glasses to frozen systems and freeze-dried solids has only begun to be explored. The list of pharmaceutically acceptable protective solutes is very short, and more imagination--and work--is needed in order to develop pharmaceutically acceptable alternative stabilizers. There is a need for technology development in process monitoring, particularly in developing a way to measure the status of the product during freezing and freeze-drying without placing temperature measurement probes in individual vials of product. The current practice of placing thermocouples in vials is uncertain with respect to reliability of the data, inconsistent with elimination of personnel in close proximity to open vials of product in an aseptic environment, and incompatible with technology for automatic material handling in freeze-drying. In addition, a method for controlling the degree of supercooling during freezing would allow better control of freezing rate and would, in many cases, result in more consistent product quality. PMID:12189727

  12. A Low-Cost Point-of-Care Testing System for Psychomotor Symptoms of Depression Affecting Standing Balance: A Preliminary Study in India

    PubMed Central

    Dutta, Arindam; Kumar, Robins; Malhotra, Suruchi; Chugh, Sanjay; Banerjee, Alakananda; Dutta, Anirban

    2013-01-01

    The World Health Organization estimated that major depression is the fourth most significant cause of disability worldwide for people aged 65 and older, where depressed older adults reported decreased independence, poor health, poor quality of life, functional decline, disability, and increased chronic medical problems. Therefore, the objectives of this study were (1) to develop a low-cost point-of-care testing system for psychomotor symptoms of depression and (2) to evaluate the system in community dwelling elderly in India. The preliminary results from the cross-sectional study showed a significant negative linear correlation between balance and depression. Here, monitoring quantitative electroencephalography along with the center of pressure for cued response time during functional reach tasks may provide insights into the psychomotor symptoms of depression where average slope of the Theta-Alpha power ratio versus average slope of baseline-normalized response time may be a candidate biomarker, which remains to be evaluated in our future clinical studies. Once validated, the biomarker can be used for monitoring the outcome of a comprehensive therapy program in conjunction with pharmacological interventions. Furthermore, the frequency of falls can be monitored with a mobile phone-based application where the propensity of falls during the periods of psychomotor symptoms of depression can be investigated further. PMID:24205436

  13. The Freezing Bomb

    ERIC Educational Resources Information Center

    Mills, Allan

    2010-01-01

    The extreme pressures that are generated when water freezes were traditionally demonstrated by sealing a small volume in a massive cast iron "bomb" and then surrounding it with a freezing mixture of ice and salt. This vessel would dramatically fail by brittle fracture, but no quantitative measurement of bursting pressure was available. Calculation…

  14. 3 CFR - Pay Freeze

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 3 The President 1 2010-01-01 2010-01-01 false Pay Freeze Presidential Documents Other Presidential Documents Memorandum of January 21, 2009 Pay Freeze Memorandum for the Assistant to the President and Chief... many more feel uncertain about the future. In these circumstances, Government must act forcefully...

  15. Major depression

    MedlinePlus

    Depression - major; Depression - clinical; Clinical depression; Unipolar depression; Major depressive disorder ... Doctors do not know the exact causes of depression. It is believed that chemical changes in the ...

  16. Freeze drying method

    DOEpatents

    Coppa, Nicholas V.; Stewart, Paul; Renzi, Ernesto

    1999-01-01

    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.

  17. Freeze drying apparatus

    DOEpatents

    Coppa, Nicholas V.; Stewart, Paul; Renzi, Ernesto

    2001-01-01

    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.

  18. Freeze drying method

    SciTech Connect

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

    1999-12-07

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

  19. High-freezing-point fuel studies

    NASA Technical Reports Server (NTRS)

    Tolle, F. F.

    1980-01-01

    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.

  20. Two-dimensional freezing criteria for crystallizing colloidal monolayers

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

  1. Two-dimensional freezing criteria for crystallizing colloidal monolayers

    SciTech Connect

    Wang Ziren; Han Yilong; Alsayed, Ahmed M.

    2010-04-21

    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 Loewen-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.

  2. Ultrasound-Assisted Freezing

    NASA Astrophysics Data System (ADS)

    Delgado, A. E.; Sun, Da-Wen

    Freezing is a well-known preservation method widely used in the food industry. The advantages of freezing are to a certain degree counterbalanced by the risk of damage caused by the formation and size of ice crystals. Over recent years new approaches have been developed to improve and control the crystallization process, and among these approaches sonocrystallization has proved to be very useful, since it can enhance both the nucleation rate and the crystal growth rate. Although ultrasound has been successfully used for many years in the evaluation of various aspects of foods and in medical applications, the use of power ultrasound to directly improve processes and products is less popular in food manufacturing. Foodstuffs are very complex materials, and research is needed in order to define the specific sound parameters that aid the freezing process and that can later be used for the scale-up and production of commercial frozen food products.

  3. Freezing and melting water in lamellar structures.

    PubMed Central

    Gleeson, J T; Erramilli, S; Gruner, S M

    1994-01-01

    The manner in which ice forms in lamellar suspensions of dielaidoylphosphatidylethanolamine, dielaidoylphosphatidylcholine, and dioleoylphosphatidylcholine in water depends strongly on the water fraction. For weight fractions between 15 and 9%, the freezing and melting temperatures are significantly depressed below 0 degree C. The ice exhibits a continuous melting transition spanning as much as 20 degrees C. When the water weight fraction is below 9%, ice never forms at temperatures as low as -40 degrees C. We show that when water contained in a lamellar lipid suspension freezes, the ice is not found between the bilayers; it exists as pools of crystalline ice in equilibrium with the bound water associated with the polar lipid headgroups. We have used this effect, together with the known chemical potential of ice, to measure hydration forces between lipid bilayers. We find exponentially decaying hydration repulsion when the bilayers are less than about 7 A apart. For larger separations, we find significant deviations from single exponential decay. PMID:7948683

  4. Pharmaceutical spray freeze drying.

    PubMed

    Wanning, Stefan; Süverkrüp, Richard; Lamprecht, Alf

    2015-07-01

    Pharmaceutical spray-freeze drying (SFD) includes a heterogeneous set of technologies with primary applications in apparent solubility enhancement, pulmonary drug delivery, intradermal ballistic administration and delivery of vaccines to the nasal mucosa. The methods comprise of three steps: droplet generation, freezing and sublimation drying, which can be matched to the requirements given by the dosage form and route of administration. The objectives, various methods and physicochemical and pharmacological outcomes have been reviewed with a scope including related fields of science and technology. PMID:25900097

  5. Freezing of Lennard-Jones-type fluids

    SciTech Connect

    Khrapak, Sergey A.; Chaudhuri, Manis; Morfill, Gregor E.

    2011-02-07

    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.

  6. Modeling soil freezing dynamics

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. Freezing and thawing processes

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. The freezing bomb

    NASA Astrophysics Data System (ADS)

    Mills, Allan

    2010-03-01

    The extreme pressures that are generated when water freezes were traditionally demonstrated by sealing a small volume in a massive cast iron 'bomb' and then surrounding it with a freezing mixture of ice and salt. This vessel would dramatically fail by brittle fracture, but no quantitative measurement of bursting pressure was available. Calculation suggests a maximum of about 55 MPa (8000 psi) might have been achieved, with some 2.3% of the water frozen into a hollow shell around the interior of the vessel. In a sufficiently strong alloy steel container the pressure might rise to a maximum of 210 MPa (30 460 psi), this limiting figure being due to the collapse of ordinary ice (ice I) to the denser forms ice II or ice III.

  9. Freezing Behavior of Water in Small Pores and the Possible Role in the Freezing of Plant Tissues

    PubMed Central

    Ashworth, Edward N.; Abeles, Fred B.

    1984-01-01

    Two model systems were used to study the freezing of water in small diameter pores. Water in pores having a diameter of less than 100 nanometers froze at lower temperatures than bulk water. Data obtained with a range of pore sizes were consistent with predicted values based on equations developed by Mazur (1965 Ann NY Acad Sci 125: 658-676), and Homshaw (1980 J Soil Sci 31: 399-414). The addition of solutes lowered the freezing point of water in small pores. We propose that the freezing behavior of water in small pores may account for some of the freezing patterns observed in plant tissues. In tissues where cells are tightly packed, share common walls, and lack intercellular spaces, the presence of water in cell wall microcapillaries would alter the freezing temperature of tissue water, impede the spread of ice, and facilitate supercooling. PMID:16663798

  10. Inactivation of Kudoa septempunctata in olive flounder meat by liquid freezing.

    PubMed

    Ohnishi, Takahiro; Akuzawa, Sayuri; Furusawa, Hiroko; Yoshinari, Tomoya; Kamata, Yoichi; Sugita-Konishi, Yoshiko

    2014-01-01

    Kudoa septempunctata in olive flounder meat was inactivated using 3 distinct freezing methods:liquid freezing for 5 min, air blast freezing at -30℃ for 5 h, and -80℃ for 1 h. The fracture curve of olive flounder meat subjected to liquid freezing resembled that of meat stored at 4℃, indicating that the structure of olive flounder muscle was well preserved. In contrast, air blast freezing induced the disappearance of the fracture point in the fracture curve, indicating that there was deterioration in the meat quality. Liquid freezing preserved the transparency of olive flounder meat to the same degree as that of meat stored at 4°C. However, air blast freezing induced meat cloudiness. These results indicate that liquid freezing can be used for K. septempunctata inactivation without affecting the meat quality. PMID:25252645

  11. Experimental investigation of molten metal freezing on to a structure

    SciTech Connect

    Mizanur Rahman, M.; Hino, Tomohiko; Morita, Koji; Matsumoto, Tatsuya; Nakagawa, Kiyoshi; Fukuda, Kenji; Maschek, Werner

    2007-10-15

    During core disruptive accidents (CDAs) of Liquid Metal Reactors (LMRs), it is important to understand the freezing phenomena of molten metal, which may prevent fuel dispersal and subsequent shutdown. The present paper describes the freezing behavior of molten metal during interaction with a structure with a view to the safety of LMRs. In this study, Wood's metal (melting point 78.8 C) was used as a simulant melt, while stainless steel and copper were used as freezing structures. A series of simulation experiments was conducted to study the freezing behavior of Wood's metal during pouring on to the freezing structures immersed in a coolant. In the experiments, simulant melt was poured into a stainless steel tube and finally ejected into a coolant through a nozzle so as to observe the freezing behavior of the molten metal. The penetration length and width were measured in the air cooled experiments, whereas penetration length and the proportion of adhering frozen metal were measured in water coolant experiment. The melt flow and distribution were observed in both types of experiment using a high-speed video camera. Distinct freezing modes were observed in the water coolant experiments, whereas only one freezing mode with a longer melt penetration was found in air coolant experiments. The present result will be utilized to create a relevant database for the verification of reactor safety analysis codes. (author)

  12. Mechanisms of Freezing lnjuly in Cellular Leve

    NASA Astrophysics Data System (ADS)

    Fujikawa, Seizo

    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.

  13. Depression - resources

    MedlinePlus

    Resources - depression ... Depression is a medical condition. If you think you may be depressed, see a health care provider. ... following organizations are good sources of information on depression : American Psychological Association -- www.apa.org/topics/depress/ ...

  14. Freeze-Tolerant Condensers

    NASA Technical Reports Server (NTRS)

    Crowley, Christopher J.; Elkouhk, Nabil

    2004-01-01

    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.

  15. H, not O or pressure, causes eutectic T depression in the Fe-FeS System to 8 GPa

    NASA Astrophysics Data System (ADS)

    Buono, Antonio S.; Walker, David

    2015-04-01

    The Fe-FeS system maintains a eutectic temperature of 990 ± 10 °C to at least 8 GPa if starting materials and pressure media are rigorously dehydrated. Literature reports of pressure-induced freezing point depression of the eutectic for the Fe-FeS system are not confirmed. Modest addition of oxygen alone is confirmed to cause negligible freezing point depression at 6 GPa. Addition of H alone causes a progressive decrease in the eutectic temperature with P in the Fe-FeS-H system to below 965 °C at 6 GPa to below 950 °C at 8 GPa. It is our hypothesis that moisture contamination in unrigorously dried experiments may be an H source for freezing point depression. O released from H2O disproportionation reacts with Fe and is sequestered as ferropericlase along the sample capsules walls, leaving the H to escape the system and/or enter the Fe-FeS mixture. The observed occurrence of ferropericlase on undried MgO capsule margins is otherwise difficult to explain, because an alternate source for the oxygen in the ferropericlase layer is difficult to identify. This study questions the use of pressure-depressed Fe-S eutectic temperatures and suggests that the lower eutectic temperatures sometimes reported are achieved by moving into the ternary Fe-S-H system. These results adjust slightly the constraints on eutectic temperatures allowed for partly solidified cores on small planets. H substantially diminishes the temperature extent of the melting interval in Fe-S by reducing the melting points of the crystalline phases more than it depresses the eutectic.

  16. Biomaterials by freeze casting.

    PubMed

    Wegst, Ulrike G K; Schecter, Matthew; Donius, Amalie E; Hunger, Philipp M

    2010-04-28

    The functional requirements for synthetic tissue substitutes appear deceptively simple: they should provide a porous matrix with interconnecting porosity and surface properties that promote rapid tissue ingrowth; at the same time, they should possess sufficient stiffness, strength and toughness to prevent crushing under physiological loads until full integration and healing are reached. Despite extensive efforts and first encouraging results, current biomaterials for tissue regeneration tend to suffer common limitations: insufficient tissue-material interaction and an inherent lack of strength and toughness associated with porosity. The challenge persists to synthesize materials that mimic both structure and mechanical performance of the natural tissue and permit strong tissue-implant interfaces to be formed. In the case of bone substitute materials, for example, the goal is to engineer high-performance composites with effective properties that, similar to natural mineralized tissue, exceed by orders of magnitude the properties of its constituents. It is still difficult with current technology to emulate in synthetic biomaterials multi-level hierarchical composite structures that are thought to be the origin of the observed mechanical property amplification in biological materials. Freeze casting permits to manufacture such complex, hybrid materials through excellent control of structural and mechanical properties. As a processing technique for the manufacture of biomaterials, freeze casting therefore has great promise. PMID:20308117

  17. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Freezing facilities. 590.534 Section..., and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off the premises, shall be capable of freezing all liquid egg products in accordance with the freezing...

  18. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Freezing facilities. 590.534 Section..., and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off the premises, shall be capable of freezing all liquid egg products in accordance with the freezing...

  19. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Freezing facilities. 590.534 Section..., and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off the premises, shall be capable of freezing all liquid egg products in accordance with the freezing...

  20. Performance Characteristics of an Isothermal Freeze Valve

    SciTech Connect

    Hailey, A.E.

    2001-08-22

    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.

  1. [Pathophysiology of depression].

    PubMed

    Tanabe, Akira; Nomura, Soichiro

    2007-09-01

    Neurobiological findings of depression are reviewed in this paper. Modern neurobiological methods have revealed pathophysiological mechanism associated with depression. Monoamine hypothesis, which was advocated in the 1950's, emphasizes that the deficiency of monoamine neurotransmitters bring about depressive symptoms. This theory played an important role in promoting the development of new antidepressants, but some inconsistent findings were pointed out concerning this theory. Neuroendocrine studies have revealed the hypothalamic-pituitary-adrenal (HPA) axis dysfunctions in depressive patients, and increased activity of HPA axis are considered as state marker of depression. Morphological changes of hippocampus, polymorphism of serotonin transporter gene, and down regulation of neurotrophin are also discussed in this review. PMID:17876979

  2. Effects of Pressure-shift Freezing on the Structural and Physical Properties of Gelatin Hydrogel Matrices

    PubMed Central

    Kim, Byeongsoo; Gil, Hyung Bae; Min, Sang-Gi; Lee, Si-Kyung; Choi, Mi-Jung

    2014-01-01

    This study investigates the effects of the gelatin concentration (10-40%, w/v), freezing temperatures (from -20? to -50?) and freezing methods on the structural and physical properties of gelatin matrices. To freeze gelatin, the pressure-shift freezing (PSF) is being applied at 0.1 (under atmospheric control), 50 and 100 MPa, respectively. The freezing point of gelatin solutions decrease with increasing gelatin concentrations, from -0.2? (10% gelatin) to -6.7? (40% gelatin), while the extent of supercooling did not show any specific trends. The rheological properties of the gelatin indicate that both the storage (G') and loss (G") moduli were steady in the strain amplitude range of 0.1-10%. To characterize gelatin matrices formed by the various freezing methods, the ice crystal sizes which were being determined by the scanning electron microscopy (SEM) are affected by the gelatin concentrations. The ice crystal sizes are affected by gelatin concentrations and freezing temperature, while the size distributions of ice crystals depend on the freezing methods. Smaller ice crystals are being formed with PSF rather than under the atmospheric control where the freezing temperature is above -40?. Thus, the results of this study indicate that the PSF processing at a very low freezing temperature (-50?) offers a potential advantage over commercial atmospheric freezing points for the formation of small ice crystals. PMID:26760743

  3. How low-permeability rocks freeze: A laboratory study on resistivity pathways of thawed, supercooled and frozen permafrost rocks

    NASA Astrophysics Data System (ADS)

    Krautblatter, M.; Zisser, N.

    2009-04-01

    Resistivity - temperature paths are among the most important proxies in permafrost research. Testing 8 sedimentary, metamorphic and igneous rocks from European permafrost summits, we found evidence that the theoretical background developed in the 70s does not describe the physics of low-permability rocks correctly, which dominate these environments. Saturated rocks with permeabilities below 10 D have an equilibrium freezing point depression of -0.5C to -1.55C and indicate metastable supercooling effects between -0.5 and -1.4 C. Instantaneous freezing from metastable stages occurs with sudden warming of the rock sample with up to 0.9C temperature difference. This is due to the spontaneous dissipation of freezing energy subsequent to supercooling. Warming occurs over tens of seconds to a few minutes and coincides with a jump in resistivity. Unfrozen and frozen temperature-resistivity paths match bilinear functions with an R of 0.88 to 1.00. The frozen temperature-resistivity gradient is 12-34 times steeper that the unfrozen resistivity gradient. Low permeability may decide the ratio of frozen and unfrozen gradients while porosity influences the 0C resistivity value and the unfrozen gradient. Here we show that separate linear approximation of unfrozen, supercooled and frozen temperature-resistivity behaviour provides a better explanation of involved physics than exponential fits.

  4. The Theory of Ice Nucleation by Heterogeneous Freezing of Deliquescent Mixed CCN. Part I: Critical Radius, Energy, and Nucleation Rate.

    NASA Astrophysics Data System (ADS)

    Khvorostyanov, Vitaly I.; Curry, Judith A.

    2004-11-01

    This paper extends previous work on the theory of heterogenous ice nucleation. The goals of this analysis are to explain empirical observations of ice nucleation and to provide a suitable framework for modeling and parameterizing the ice nucleation process in cloud-scale and large-scale atmospheric models. Considered are the processes of heterogeneous freezing of deliquescent mixed cloud condensation nuclei that may serve as ice nuclei, and the properties of an ice germ critical radius, energy, and nucleation rate of ice crystals are examined as functions of temperature and supersaturation. Expressions for nucleation in a polydisperse aerosol for the deliquescence-freezing mode are developed. Equations are derived for the threshold and critical saturation ratios as functions of temperature and nucleation rate, and for the threshold and critical temperatures as functions of saturation ratio. Equivalence of the new formulation for the freezing point depression with traditional expressions is shown and the concepts of the effective temperature and supercooling are introduced. These new formulations are used in a companion paper for simulations of ice nucleation using a cloud parcel model.


  5. Freezing of living cells

    SciTech Connect

    Mazur, P.

    1985-01-01

    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.

  6. Understanding Slag Freeze Linings

    NASA Astrophysics Data System (ADS)

    Fallah-Mehrjardi, Ata; Hayes, Peter C.; Jak, Evgueni

    2014-09-01

    Slag freeze linings, the formation of protective deposit layers on the inner walls of furnaces and reactors, are increasingly used in industrial pyrometallurgical processes to ensure that furnace integrity is maintained in these aggressive, high-temperature environments. Most previous studies of freeze-linings have analyzed the formation of slag deposits based solely on heat transfer considerations. These thermal models have assumed that the interface between the stationary frozen layer and the agitated molten bath at steady-state deposit thickness consists of the primary phase, which stays in contact with the bulk liquid at the liquidus temperature. Recent experimental studies, however, have clearly demonstrated that the temperature of the deposit/liquid bath interface can be lower than the liquidus temperature of the bulk liquid. A conceptual framework has been proposed to explain the observations and the factors influencing the microstructure and the temperature of the interface at steady-state conditions. The observations are consistent with a dynamic steady state that is a balance between (I) the rate of nucleation and growth of solids on detached crystals in a subliquidus layer as this fluid material moves toward the stagnant deposit interface and (II) the dissolution of these detached crystals as they are transported away from the interface by turbulent eddies. It is argued that the assumption that the interface temperature is the liquidus of the bulk material represents only a limiting condition, and that the interface temperature can be between T liquidus and T solidus depending on the process conditions and bath chemistry. These findings have implications for the modeling approach and boundary conditions required to accurately describe these systems. They also indicate the opportunity to integrate considerations of heat and mass flows with the selection of melt chemistries in the design of future high temperature industrial reactors.

  7. Coil freezing: What a relief!

    SciTech Connect

    Jacobs, T.L.

    1995-12-01

    This article describes why a coil freezes, what happens during the freezing, and what is required to alleviate the damage. Water and steam have been used to cool and heat air in finned-tube heat exchanger coils almost since the inception of heating and air conditioning. Freezing of the fluid and the resultant coil damage have also been around for the same length of time. It is a systematic problem that many times is preventable, but one knows that this is not a perfect world. Nor are the HVAC and process systems that have been in service for decades. It is fairly simple to understand the basics of a liquid phase freeze. The ambient conditions must be at or below 32 F, and that can, in turn cause the water inside the coil to fall below 32 F as well. If kept below the freezing temperature of fluid long enough, the coil may be damaged by this condition.

  8. Depression (PDQ)

    MedlinePlus

    ... risk of depression. Depression is different from normal sadness. Depression is not simply feeling sad. Depression is ... day to day living. Money and legal concerns. Sadness and grief are normal reactions to a cancer ...

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

    PubMed

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

    2013-07-01

    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

  10. Summer Freezing Resistance: A Critical Filter for Plant Community Assemblies in Mediterranean High Mountains.

    PubMed

    Pescador, David S; Sierra-Almeida, Ángela; Torres, Pablo J; Escudero, Adrián

    2016-01-01

    Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain) by measuring their ice nucleation temperature, freezing point (FP), and low-temperature damage (LT50), as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance). The community response to freezing was estimated for each plot as community weighted means (CWMs) and functional diversity (FD), and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content (LDMC), and seed mass). There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the FD of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only leaf dry matter content was negatively correlated with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower FD of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to be a general prerequisite for plants found in xeric mountains. PMID:26941761

  11. Summer Freezing Resistance: A Critical Filter for Plant Community Assemblies in Mediterranean High Mountains

    PubMed Central

    Pescador, David S.; Sierra-Almeida, Ángela; Torres, Pablo J.; Escudero, Adrián

    2016-01-01

    Assessing freezing community response and whether freezing resistance is related to other functional traits is essential for understanding alpine community assemblages, particularly in Mediterranean environments where plants are exposed to freezing temperatures and summer droughts. Thus, we characterized the leaf freezing resistance of 42 plant species in 38 plots at Sierra de Guadarrama (Spain) by measuring their ice nucleation temperature, freezing point (FP), and low-temperature damage (LT50), as well as determining their freezing resistance mechanisms (i.e., tolerance or avoidance). The community response to freezing was estimated for each plot as community weighted means (CWMs) and functional diversity (FD), and we assessed their relative importance with altitude. We established the relationships between freezing resistance, growth forms, and four key plant functional traits (i.e., plant height, specific leaf area, leaf dry matter content (LDMC), and seed mass). There was a wide range of freezing resistance responses and more than in other alpine habitats. At the community level, the CWMs of FP and LT50 responded negatively to altitude, whereas the FD of both traits increased with altitude. The proportion of freezing-tolerant species also increased with altitude. The ranges of FP and LT50 varied among growth forms, and only leaf dry matter content was negatively correlated with freezing-resistance traits. Summer freezing events represent important abiotic filters for assemblies of Mediterranean high mountain communities, as suggested by the CWMs. However, a concomitant summer drought constraint may also explain the high freezing resistance of species that thrive in these areas and the lower FD of freezing resistance traits at lower altitudes. Leaves with high dry matter contents may maintain turgor at lower water potential and enhance drought tolerance in parallel to freezing resistance. This adaptation to drought seems to be a general prerequisite for plants found in xeric mountains. PMID:26941761

  12. Biomimetic Materials by Freeze Casting

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

  13. Benchmarking numerical freeze/thaw models

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  14. Role of Heart and its Diseases in the Etiology of Depression According to Avicenna's Point of View and its Comparison with Views of Classic Medicine

    PubMed Central

    Yousofpour, Mohammad; Kamalinejad, Mohammad; Esfahani, Mohammad Mahdi; Shams, Jamal; Tehrani, Hassan Hoshdar; Bahrami, Mohsen

    2015-01-01

    Background: Depression is one of the most important medical problems in today's world; despite its high prevalence, its causes unfortunately remain not fully known. Among important issues regarding this is its relation with heart diseases. Based on studies this comorbidity increase morbidity and mortality and leads to worst prognosis. However the cause of such high rate of comorbidity is unclear and instead of efforts to understand this correlation has prompted the medical world to consult other medicinal disciplines, not only to find the answer but also to increase the effectiveness of treatment and decrease its cost. Methods: We first reviewed the most important ancient causes for depression mentioned by Avicenna and considered those as the key words for our next step. Then, we made a literature search (PubMed and Scopus) with those key words to find out new scientific findings in modern medicine about the Avicenna's suggestions. Results: Avicenna does not regard depression as only a mental ailment, but as a disorder resulted by the involvement of brain, heart and blood. He believed that the main causes of depressive events are rooted in heart diseases; in most cases brain is only affected secondary to the heart. Thus he declared that for the treatment of depressive disorders, the underlying cardiovascular diseases should be considered. Conclusions: It is worthwhile to consider the Avicenna's recommended causes of depression and to design future scientific studies based on his suggestions. PMID:26124946

  15. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  16. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  17. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Freezing operations. 590.536 Section..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean and... products shall be examined by organoleptic examination after freezing to determine their fitness for...

  18. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  19. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  20. 7 CFR 58.621 - Freezing tunnels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Freezing tunnels. 58.621 Section 58.621 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....621 Freezing tunnels. Freezing tunnels for quick freezing at extremely low temperatures shall...

  1. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Freezing operations. 590.536 Section..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean and... products shall be examined by organoleptic examination after freezing to determine their fitness for...

  2. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Freezing operations. 590.536 Section..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean and... products shall be examined by organoleptic examination after freezing to determine their fitness for...

  3. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Freezing operations. 590.536 Section..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean and... products shall be examined by organoleptic examination after freezing to determine their fitness for...

  4. 9 CFR 590.536 - Freezing operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Freezing operations. 590.536 Section..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean and... products shall be examined by organoleptic examination after freezing to determine their fitness for...

  5. Sub-ice Stream Till Properties: Changes Induced By Basal Freeze-on and The Influence of Subglacial Hydrogeology

    NASA Astrophysics Data System (ADS)

    Christoffersen, P.; Tulaczyk, S.

    The physical properties of weak and porous sub-ice stream till are changed character- istically when the thermal regimen changes from melting to freezing. These property changes influence the dynamics of ice streams and may control the location of shear margins and inter-stream ridges. Basal freeze-on can be a trigger of ice stream stop- page or it can occur due to the decrease in basal shear heating that accompanies the stoppage. In a high resolution (ca. 0.01 m) numerical model, we investigate the re- sponse of subglacial sediments to basal freeze-on. In-situ freezing of pore water is prevented in fine-grained sub-ice stream till due to the surface tension (ca. 100 kPa) that are associated with a small characteristic particles size (ca. 10^-6 m). The till be- comes super-cooled, and the response to freezing is a characteristic flow of pore water towards the ice base where clean ice accretes. The basal temperature is depressed by several tens of a degree below the pressure-melting point and discrete lenses of segregation ice develop within the till. Till with a low surface tension (ca. 25 kPa) is associated with development of thin ice lenses (ca. 0.02 m) that are closely spaced (ca. 0.30 m). A higher value of surface tension (ca. 100 kPa) is associated with thicker ice lenses (ca. 0.25 m) with a wider spacing (ca. 0.85 m). Complete freeze-up will eventu- ally create a uniquely layered basal zone consisting of uniform bands of debris-filled ice and clean segregation ice. Basal freeze-on beneath West Antarctic ice streams may increase the shear strength of initially weak and porous till (ca. 2 kPa), not only to a level that prevents fast ice streaming (ca. 13 kPa), but also to level that produces a high degree of consolidation (>100 kPa). Significant property changes take place mainly after ice stream shutdown due to the continuous extraction of pore water. The grain size distribution of the till and the hydrogeological setting control the property changes that succeed shut-down. Despite freezing bed conditions, the bed may remain unfrozen and highly porous (> 30 %) if the sub-till sediment can supply water to the freeze-on process. However, if the till is fine-grained and if the sub-till sediment is im- permeable, pore water may be extracted to a degree that causes significant reduction of porosity (<20 %) and high basal shear strengths (>100 kPa). Our model predictions compare favourably with the thermal setting of the now stagnant Ice Stream C where the freeze-on rate is 4 mm/y.

  6. Facing freeze: social threat induces bodily freeze in humans.

    PubMed

    Roelofs, Karin; Hagenaars, Muriel A; Stins, John

    2010-11-01

    Freezing is a common defensive response in animals threatened by predators. It is characterized by reduced body motion and decreased heart rate (bradycardia). However, despite the relevance of animal defense models in human stress research, studies have not shown whether social threat cues elicit similar freeze-like responses in humans. We investigated body sway and heart rate in 50 female participants while they were standing on a stabilometric force platform and viewing cues that were socially threatening, socially neutral, and socially affiliative (angry, neutral, and happy faces, respectively). Posturographic analyses showed that angry faces (compared with neutral faces and happy faces) induced significant reductions in body sway. In addition, the reduced body sway for angry faces was accompanied by bradycardia and correlated significantly with subjective anxiety. Together, these findings indicate that spontaneous body responses to social threat cues involve freeze-like behavior in humans that mimics animal freeze responses. These findings open avenues for studying human freeze responses in relation to various sociobiological markers and social-affective disorders. PMID:20876881

  7. Hepatitis B vaccine freezing in the Indonesian cold chain: evidence and solutions.

    PubMed Central

    Nelson, Carib M.; Wibisono, Hariadi; Purwanto, Hary; Mansyur, Isa; Moniaga, Vanda; Widjaya, Anton

    2004-01-01

    OBJECTIVES: To document and characterize freezing temperatures in the Indonesian vaccine cold chain and to evaluate the feasibility of changes designed to reduce the occurrence of freezing. METHODS: Data loggers were used to measure temperatures of shipments of hepatitis B vaccine from manufacturer to point of use. Baseline conditions and three intervention phases were monitored. During each of the intervention phases, vaccines were removed progressively from the standard 2-8 degrees C cold chain. FINDINGS: Freezing temperatures were recorded in 75% of baseline shipments. The highest rates of freezing occurred during transport from province to district, storage in district-level ice-lined refrigerators, and storage in refrigerators in health centres. Interventions reduced freezing, without excessive heat exposure. CONCLUSIONS: Inadvertent freezing of freeze-sensitive vaccines is widespread in Indonesia. Simple strategies exist to reduce freezing - for example, selective transport and storage of vaccines at ambient temperatures. The use of vaccine vial monitors reduces the risk associated with heat-damaged vaccines in these scenarios. Policy changes that allow limited storage of freeze-sensitive vaccines at temperatures >2-8 degrees C would enable flexible vaccine distribution strategies that could reduce vaccine freezing, reduce costs, and increase capacity. PMID:15042231

  8. Novel real-time diagnosis of the freezing process using an ultrasonic transducer.

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  10. Freeze-fracture cytochemistry: partition of glycophorin in freeze- fractured human erythrocyte membranes

    PubMed Central

    1982-01-01

    Thin-section and critical-point-dried fracture-labeled preparations are used to determine the distribution and partition of glycophorin- associated wheat germ agglutinin (WGA) binding sites over protoplasmic and exoplasmic faces of freeze-fractured human erythrocyte membranes. Most wheat germ agglutinin binding sites are found over exoplasmic faces. Label is sparse over the protoplasmic faces. These results contrast with previous observations of the partition of band 3 component where biochemical analysis and fracture-label of concanavalin A (Con A) binding sites show preferential partition of this transmembrane protein with the protoplasmic face. Presence of characteristic proportions of WGA and Con A binding sites over each fracture face is interpreted to indicate the operation of a stochastic process during freeze-fracture. This process appears modulated by the relative expression of each transmembrane protein at either surface as well as by their association to components of the erythrocyte membrane skeleton. PMID:7096449

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

    PubMed

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

    1994-08-01

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

  12. Caregiver Depression

    MedlinePlus

    ... will not sell or share your name. Caregiver Depression Tweet Bookmark this page | Email | Print Many caregivers ... depression See your doctor Treatment Coping Symptoms of depression Caregiving is hard — and can lead to feelings ...

  13. Postpartum depression

    MedlinePlus

    Depression - postpartum; Postnatal depression; Postpartum psychological reactions ... The exact causes of postpartum depression are unknown. Changes in hormone levels during and after pregnancy may affect a woman’s mood. Many non-hormonal factors may also ...

  14. Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities

    NASA Astrophysics Data System (ADS)

    Marcolli, C.

    2013-06-01

    Heterogeneous ice nucleation is an important mechanism for the glaciation of mixed phase clouds and may also be relevant for cloud formation and dehydration at the cirrus cloud level. It is thought to proceed through different mechanisms, namely contact, condensation, immersion and deposition nucleation. Supposedly, deposition nucleation is the only pathway which does not involve liquid water but occurs by direct water vapor deposition on a surface. This study challenges this classical view by putting forward the hypothesis that what is called deposition nucleation is in fact homogeneous or immersion nucleation occurring in pores and cavities that may form between aggregated primary particles and fill with water at relative humidity RHw < 100% because of the inverse Kelvin effect. Evidence for this hypothesis of pore condensation and freezing (PCF) originates from a number of only loosely connected scientific areas. The prime example for PCF is ice nucleation in clay minerals and mineral dusts, for which the data base is best. Studies on freezing in confinement carried out on mesoporous silica materials such as SBA-15, SBA-16, MCM-41, zeolites and KIT have shown that homogeneous ice nucleation occurs abruptly at T=230-235 K in pores with diameters (D) of 3.5-4 nm or larger but only gradually at T=210-230 K in pores with D=2.5-3.5 nm. Melting temperatures in pores are depressed by an amount that can be described by the Gibbs-Thomson equation. Water adsorption isotherms of MCM-41 show that pores with D=3.5-4 nm fill with water at RHw = 56-60% in accordance with an inverse Kelvin effect. Water in such pores should freeze homogeneously for T < 235 K even before relative humidity with respect to ice (RHi) reaches ice saturation. Ice crystal growth by water vapor deposition from the gas phase is therefore expected to set in as soon as RHw > 100%. Pores with D > 7.5 nm fill with water at RHi > 100% for T < 235 K and are likely to freeze homogeneously as soon as they are filled with water. Water in pores can freeze in immersion mode at T > 235 K if the pore walls contain an active site. Pore analysis of clay minerals shows that kaolinites exhibit pore structures with pore diameters of 20-50 nm. The mesoporosity of illites and montmorillonites is characterized by pores with T = 2-5 nm. The number and size of pores is distinctly increased in acid treated montmorillonites like K10. Many clay minerals and mineral dusts show a strong increase in ice nucleation efficiency when temperature is decreased below 235 K. Such an increase is difficult to explain when ice nucleation is supposed to occur by a deposition mechanism, but evident when assuming freezing in pores, because for homogeneous ice nucleation only small pore volumes are needed, while heterogeneous ice nucleation requires larger pore structures to contain at least one active site for immersion nucleation. Together, these pieces of evidence strongly suggest that ice nucleation within pores should be the prevailing freezing mechanism of clay minerals for RHw below water saturation. Extending the analysis to other types of ice nuclei shows that freezing in pores and cracks is probably the prevailing ice nucleation mechanism for glassy and volcanic ash aerosols at RHw below water saturation. Freezing of water in carbon nanotubes might be of significance for ice nucleation by soot aerosols. No case could be identified that gives clear evidence of ice nucleation by water vapor deposition on a solid surface. Inspection of ice nuclei with a close lattice match to ice, such as silver iodide or SnomaxTM, show that for high ice nucleation efficiency below water saturation the presence of impurities or cracks on the surface may be essential. Soluble impurities promote the formation of a liquid phase below water saturation in patches on the surface or as a complete surface layer that offers an environment for immersion freezing. If porous aerosol particles come in contact with semivolatile vapors, these will condense preferentially in pores before a coating on the surface of the particles is formed. A pore partially filled with condensed species attracts water at lower RHw than an empty pore, but the aqueous solution that forms in the pore will freeze at a higher RHi than pure water. The ice nucleation ability of pores completely filled with condensed organic species might be totally impeded. Pores might also be important for preactivation, the capability of a particle to nucleate ice at lower RHi in subsequent experiments when compared to the first initial ice nucleation event. Preactivation has often been explained by persistence of ice embryos at specific sites like dislocations, steps, kinks or pores. However, it is not clear how such features can preserve an ice embryo at RHi < 100%. Rather, ice embryos could be preserved when embedded in water. To keep liquid water at RHw well below 100%, narrow pores are needed but to avoid a strong melting point depression large pores are favorable. A narrow pore opening and a large inner volume are combined in "ink bottle" pores. Such "ink bottle" pores would be suited to preserve ice at RHi < 100% and can arise e.g. in spaces between aggregated particles.

  15. ANNAGNPS: ACCOUNTING FOR SNOWPACK, SNOWMELT, FREEZING AND THAWING OF SOIL

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The watershed model, AnnAGNPS (Annualized AGricultural Non-Point Source Pollution model) has been enhanced by incorporating winter climate algorithms that account for frozen soil conditions. The model includes snowpack accumulation and melt, and the freeze/thaw process in the soil. Three major imp...

  16. A Model for Prediction of Shrinkage Defects in Long and Short Freezing Range Materials

    SciTech Connect

    Reis, A.; Duarte, J. F.; Santos, A. D.; Magalhaes, A. B.; Houbaert, Y.

    2007-05-17

    The aim of the model presented in this paper is to capture the difference in solidification behaviour of long and short freezing materials. The shrinkage defects in short freezing materials tends to be internal, as porosity, while in long freezing materials these defects tend to be external in the form of surface depressions. To achieve this, a pressure drop based 3-D feeding flow model has been developed to evaluate shrinkage defects for casting alloys. A continuum formulation is used to describe the transport of mass, energy and momentum. It is assumed that during solidification the driving force for flow is shrinkage. A Darcy type source term has been included in the momentum equation to account for flow resistance in the mushy zone. A VOF free surface model has been used to describe shrinkage defects, i.e., external surface depressions and internal shrinkage porosities, while ensuring mass conservation. The model is used to calculate the shrinkage in a simple casting. The results shows internal and outside shrinkage defects depending on the freezing range of the metal. Short freezing range results mainly in internal shrinkage whereas the long freezing range results in external shrinkage. The expected shrinkage features are well described by the present model.

  17. Basic concepts in freezing cells

    SciTech Connect

    Mazur, P.

    1985-01-01

    Freezing involves the lowering of temperature and the formation of ice. Most cells have not been found to be sensitive to the former; rather injury is a consequence of the removal of water from the system in the form of ice. Some cells such as boar sperm and those of many tropical crops are susceptible to even short-term lowering of temperature to near O/sup 0/C. This susceptiblity, which is independent of the rate of temperature drop, is defined as chilling injury. Other cells are injured by chilling only if the rate of cooling is high, a phenomenon referred to as thermal shock. This paper discusses the physical-chemical events during freezing and on freezing injury will assume that lowered temperature per se is not injurious.

  18. Freeze-in through portals

    SciTech Connect

    Blennow, Mattias; Fernandez-Martínez, Enrique; Zaldívar, Bryan E-mail: enrique.fernandez-martinez@uam.es

    2014-01-01

    The popular freeze-out paradigm for Dark Matter (DM) production, relies on DM-baryon couplings of the order of the weak interactions. However, different search strategies for DM have failed to provide a conclusive evidence of such (non-gravitational) interactions, while greatly reducing the parameter space of many representative models. This motivates the study of alternative mechanisms for DM genesis. In the freeze-in framework, the DM is slowly populated from the thermal bath while never reaching equilibrium. In this work, we analyse in detail the possibility of producing a frozen-in DM via a mediator particle which acts as a portal. We give analytical estimates of different freeze-in regimes and support them with full numerical analyses, taking into account the proper distribution functions of bath particles. Finally, we constrain the parameter space of generic models by requiring agreement with DM relic abundance observations.

  19. Freezing of a liquid marble.

    PubMed

    Hashmi, Ali; Strauss, Adam; Xu, Jie

    2012-07-17

    In this study, we present for the first time the observations of a freezing liquid marble. In the experiment, liquid marbles are gently placed on the cold side of a thermo-electric cooler (TEC), and the morphological changes are recorded and characterized thereafter. These liquid marbles are noticed to undergo a shape transition from a spherical to a flying-saucer-shaped morphology. The freezing dynamics of liquid marbles is observed to be very different from that of a freezing water droplet on a superhydrophobic surface. For example, the pointy tip appearing on a frozen water drop could not be observed for a frozen liquid marble. In the end, we highlight a possible explanation of the observed morphology. PMID:22746403

  20. Water freezing and ice melting

    DOE PAGESBeta

    Malolepsza, Edyta; Keyes, Tom

    2015-10-12

    The generalized replica exchange method (gREM) is designed to sample states with coexisting phases and thereby to describe strong first order phase transitions. The isobaric MD version of the gREM is presented and applied to freezing of liquid water, and melting of hexagonal and cubic ice. It is confirmed that coexisting states are well sampled. The statistical temperature as a function of enthalpy, TS(H), is obtained. Hysteresis between freezing and melting is observed and discussed. The entropic analysis of phase transitions is applied and equilibrium transition temperatures, latent heats, and surface tensions are obtained for hexagonal ice↔liquid and cubic ice↔liquid,more » with excellent agreement with published values. A new method is given to assign water molecules among various symmetry types. As a result, pathways for water freezing, ultimately leading to hexagonal ice, are found to contain intermediate layered structures built from hexagonal and cubic ice.« less

  1. Water freezing and ice melting

    SciTech Connect

    Malolepsza, Edyta; Keyes, Tom

    2015-10-12

    The generalized replica exchange method (gREM) is designed to sample states with coexisting phases and thereby to describe strong first order phase transitions. The isobaric MD version of the gREM is presented and applied to freezing of liquid water, and melting of hexagonal and cubic ice. It is confirmed that coexisting states are well sampled. The statistical temperature as a function of enthalpy, TS(H), is obtained. Hysteresis between freezing and melting is observed and discussed. The entropic analysis of phase transitions is applied and equilibrium transition temperatures, latent heats, and surface tensions are obtained for hexagonal ice↔liquid and cubic ice↔liquid, with excellent agreement with published values. A new method is given to assign water molecules among various symmetry types. As a result, pathways for water freezing, ultimately leading to hexagonal ice, are found to contain intermediate layered structures built from hexagonal and cubic ice.

  2. Water Freezing and Ice Melting.

    PubMed

    Małolepsza, Edyta; Keyes, Tom

    2015-12-01

    The generalized replica exchange method (gREM) is designed to sample states with coexisting phases and thereby to describe strong first order phase transitions. The isobaric MD version of the gREM is presented and applied to the freezing of liquid water and the melting of hexagonal and cubic ice. It is confirmed that coexisting states are well-sampled. The statistical temperature as a function of enthalpy, TS(H), is obtained. Hysteresis between freezing and melting is observed and discussed. The entropic analysis of phase transitions is applied and equilibrium transition temperatures, latent heats, and surface tensions are obtained for hexagonal ice ↔ liquid and cubic ice ↔ liquid with excellent agreement with published values. A new method is given to assign water molecules among various symmetry types. Pathways for water freezing, ultimately leading to hexagonal ice, are found to contain intermediate layered structures built from hexagonal and cubic ice. PMID:26642983

  3. Freeze-dried microarterial allografts

    SciTech Connect

    Raman, J.; Hargrave, J.C.

    1990-02-01

    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.

  4. Synchrotron x-ray visualisation of ice formation in insects during lethal and non-lethal freezing.

    PubMed

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

    2009-01-01

    Although the biochemical correlates of freeze tolerance in insects are becoming well-known, the process of ice formation in vivo is subject to speculation. We used synchrotron x-rays to directly visualise real-time ice formation at 3.3 Hz in intact insects. We observed freezing in diapausing 3(rd) instar larvae of Chymomyza amoena (Diptera: Drosophilidae), which survive freezing if it occurs above -14 degrees C, and non-diapausing 3(rd) instar larvae of C. amoena and Drosophila melanogaster (Diptera: Drosophilidae), neither of which survive freezing. Freezing was readily observed in all larvae, and on one occasion the gut was seen to freeze separately from the haemocoel. There were no apparent qualitative differences in ice formation between freeze tolerant and non-freeze tolerant larvae. The time to complete freezing was positively related to temperature of nucleation (supercooling point, SCP), and SCP declined with decreasing body size, although this relationship was less strong in diapausing C. amoena. Nucleation generally occurred at a contact point with the thermocouple or chamber wall in non-diapausing larvae, but at random in diapausing larvae, suggesting that the latter have some control over ice nucleation. There were no apparent differences between freeze tolerant and non-freeze tolerant larvae in tracheal displacement or distension of the body during freezing, although there was markedly more distension in D. melanogaster than in C. amoena regardless of diapause state. We conclude that although control of ice nucleation appears to be important in freeze tolerant individuals, the physical ice formation process itself does not differ among larvae that can and cannot survive freezing. This suggests that a focus on cellular and biochemical mechanisms is appropriate and may reveal the primary adaptations allowing freeze tolerance in insects. PMID:20011523

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

    PubMed Central

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

    2009-01-01

    Although the biochemical correlates of freeze tolerance in insects are becoming well-known, the process of ice formation in vivo is subject to speculation. We used synchrotron x-rays to directly visualise real-time ice formation at 3.3 Hz in intact insects. We observed freezing in diapausing 3rd instar larvae of Chymomyza amoena (Diptera: Drosophilidae), which survive freezing if it occurs above −14°C, and non-diapausing 3rd instar larvae of C. amoena and Drosophila melanogaster (Diptera: Drosophilidae), neither of which survive freezing. Freezing was readily observed in all larvae, and on one occasion the gut was seen to freeze separately from the haemocoel. There were no apparent qualitative differences in ice formation between freeze tolerant and non-freeze tolerant larvae. The time to complete freezing was positively related to temperature of nucleation (supercooling point, SCP), and SCP declined with decreasing body size, although this relationship was less strong in diapausing C. amoena. Nucleation generally occurred at a contact point with the thermocouple or chamber wall in non-diapausing larvae, but at random in diapausing larvae, suggesting that the latter have some control over ice nucleation. There were no apparent differences between freeze tolerant and non-freeze tolerant larvae in tracheal displacement or distension of the body during freezing, although there was markedly more distension in D. melanogaster than in C. amoena regardless of diapause state. We conclude that although control of ice nucleation appears to be important in freeze tolerant individuals, the physical ice formation process itself does not differ among larvae that can and cannot survive freezing. This suggests that a focus on cellular and biochemical mechanisms is appropriate and may reveal the primary adaptations allowing freeze tolerance in insects. PMID:20011523

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    Saline permafrost and cryopegs (hypersaline unfrozen layers/zones within permafrost) are widespread in the Arctic coastal area as a result of marine transgression and regression in recent geological history. Owing to the freezing-point depression effect of soluble salts, they contain more unfrozen water than non-saline frozen sediments when subjected to the same permafrost temperatures (e.g., from 0 to -15 °C). Mapping subsurface cryopeg structure remains a challenging geophysical task due to the poor penetration of GPR in highly conductive fluids and related limitations for lower frequency EM techniques. Seismic profiling, particularly surface wave characterization, provides one possible approach to delineate the extent of cryopeg bodies. However, interpretation of such surveys is currently limited by the sparse database of measurements examining the seismic properties of unconsolidated materials saturated with saline fluids at sub-zero temperatures. We present the results of experiments examining seismic velocity in the ultrasonic range for both synthetic and natural permafrost sediments during freeze/thaw cycles; in these experiments, use of a range of brine salinities allows us to evaluate the properties of cryopeg sediments at in-situ conditions, a prerequisite for quantitative interpretation of seismic imaging results. Because of the abundant unfrozen water and less developed inter-granular ice structure, the seismic properties of saline permafrost typically falls between frozen and unfrozen soils. We conducted ultrasonic measurements of a freeze-thaw cycle on 20-30 Ottawa sand (grain size 590-840 μm) 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.

  7. Non-freezing cold injury.

    PubMed

    Glennie, J S; Milner, R

    2014-01-01

    Non-freezing cold injury can be a diagnostic challenge for clinicians in the United Kingdom Armed Forces. It is associated with operations in adverse climatic conditions, and may result in significant long-term morbidity. In this article we discuss the operational importance of this condition and the current best practice in its management and prevention. PMID:25895405

  8. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... PRODUCTS INSPECTION INSPECTION OF EGGS AND EGG PRODUCTS (EGG PRODUCTS INSPECTION ACT) Sanitary, Processing, and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off...

  9. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... PRODUCTS INSPECTION INSPECTION OF EGGS AND EGG PRODUCTS (EGG PRODUCTS INSPECTION ACT) Sanitary, Processing, and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off...

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

    NASA Technical Reports Server (NTRS)

    Cutbirth, J. Michael

    2012-01-01

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

  11. Entropy Budgets in Oscillating and Freezing Systems

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.

    2005-12-01

    An interesting spontaneously oscillating system was demonstrated some decades ago by Welander : an open-topped water tank supplied with a continuous supply of heat is exposed to chilled air. A layer of ice forms, as one might expect. However, the ice retards the loss of heat to the air, and the water temperature rises until eventually the ice melts. The enhanced heat loss allows the system to cool again to the point where ice can form, and the cycle repeats. The oscillating behaviour is counterintuitive (like another freezing phenomenon, the Mpemba effect, wherein a warm liquid will begin freezing before a cool one), but is in full accord with the laws of thermodynamics and can be demonstrated in the laboratory and with numerical models. Oscillations occur in specific regions of parameter space (heating rate, heat transfer coefficients etc) - smooth variation, e.g. of the ice:air heat transfer coefficient yields a smooth variation of entropy production, except for a jump to increased entropy production when oscillations begin. A geophysical system where similar oscillations may occur is the icy Jovian satellite Europa, which appears to have a young crust. More generally, where a system is subject to a varying excitation (such as diurnal or seasonal forcing of the climate of Earth or Mars) the presence of phase changes such as melting of water or the condensation of carbon dioxide as frost have an important impact on the entropy budget of the system.

  12. Freeze-drying today and tomorrow.

    PubMed

    Leary, J H; Stanford, E A

    1976-10-01

    The freeze-drying process and equipment have been improved over the years; the cycle times have shortened and the dried products have improved as a result. This talk will deal with these improvements and how we have progressed from the early systems to where we are today. Such areas of discussion will include: vacuum pumping systems, how they are sized and designed to meet the needs for general and special applications; heat transfer systems, and their use in maintaining the drying profile; condensing surface design, and what is best for certain types of dryers; controls and instrumentation, and how these have played a big part in the drying process and have made it possible to get repeatability; refrigeration systems, and the part they play in the performance of freeze-drying; and lastly the effect of internal stoppering, bottomless trays, and other items such as these have had on the present state of the art. It goes without saying that there have been many changes and there will continue to be changes and we shall endeavor to look into the future--as to what might well bo some of these changes. Included in the talk will be a number of slides and illustrations to point out the various items as they are discussed. PMID:1030422

  13. Temperature and flow measurements on near-freezing aviation fuels in a wing-tank model

    NASA Technical Reports Server (NTRS)

    Friedman, R.; Stockemer, F. J.

    1980-01-01

    Freezing behavior, pumpability, and temperature profiles for aviation turbine fuels were measured in a 190-liter tank, to simulate internal temperature gradients encountered in commercial airplane wing tanks. Two low-temperature situations were observed. Where the bulk of the fuel is above the specification freezing point, pumpout of the fuel removes all fuel except a layer adhering to the bottom chilled surfaces, and the unpumpable fraction depends on the fuel temperature near these surfaces. Where the bulk of the fuel is at or below the freezing point, pumpout ceases when solids block the pump inlet, and the unpumpable fraction depends on the overall average temperature.

  14. Temperature and flow measurements on near-freezing aviation fuels in a wing-tank model

    NASA Technical Reports Server (NTRS)

    Friedman, R.; Stockemer, F. J.

    1980-01-01

    Freezing behavior, pumpability, and temperature profiles for aviation turbine fuels were measured in a 190-liter tank chilled to simulate internal temperature gradients encountered in commercial airplane wing tanks. When the bulk of the fuel was above the specification freezing point, pumpout of the fuel removed all fuel except a layer adhering to the bottom chilled surfaces, and the unpumpable fraction depended on the fuel temperature near these surfaces. When the bulk of the fuel was at or below the freezing point, pumpout ceased when solids blocked the pump inlet, and the unpumpable fraction depended on the overall average temperature.

  15. Thermal analysis on the realization of the tin fixed point

    NASA Astrophysics Data System (ADS)

    Tsai, S. F.

    2013-09-01

    A study on the thermal analysis of a new tin fixed-point open cell within a new three-zone furnace was carried out. The stability at the setting temperatures of liquid-solid coexisting together with some degree Celsius lower and higher than the tin fixed point; and the axial uniformity of furnace while tin is still in solid phase were investigated and analyzed. The impurities effect on the depression in temperature was investigated in terms of ΔT (Tobserved-T1/F=0) and the inverse of the melted fraction (1/F) relationship during the melting and the following freezing realizations at various temperature settings of furnace. These thermal analysis results were also compared with those estimated by the CCT-WG1 recommended SIE (sum of individual estimates) method, which leads to a temperature correction along with a corresponding uncertainty through the individual impurity content detected by GDMS (glow discharge mass spectrometry).

  16. 7 CFR 51.1562 - Freezing.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Freezing. 51.1562 Section 51.1562 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Potatoes 1 Definitions § 51.1562 Freezing. Freezing means that the potato is frozen or shows evidence of having been frozen....

  17. 7 CFR 51.1562 - Freezing.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Freezing. 51.1562 Section 51.1562 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Potatoes 1 Definitions § 51.1562 Freezing. Freezing means that the potato is...

  18. 7 CFR 51.1562 - Freezing.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Freezing. 51.1562 Section 51.1562 Agriculture..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Potatoes 1 Definitions § 51.1562 Freezing. Freezing means that the potato is frozen or shows evidence of having been frozen....

  19. 7 CFR 51.1562 - Freezing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Freezing. 51.1562 Section 51.1562 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Potatoes 1 Definitions § 51.1562 Freezing. Freezing means that the potato is...

  20. 7 CFR 51.1562 - Freezing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Freezing. 51.1562 Section 51.1562 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Grades of Potatoes 1 Definitions § 51.1562 Freezing. Freezing means that the potato is...

  1. Measuring freezing tolerance: Survival and regrowth assays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Screening plants for freezing tolerance under tightly-controlled conditions is an invaluable technique for studying freezing tolerance and selecting for improved winterhardiness. Artificial freezing tests of cereal plants historically have used isolated crown and stem tissue prepared by “removing a...

  2. Combined infrared and freeze-drying.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The drying of the combined infrared (IR) and freeze-drying of food materials has been shown to be very rapid compared to regular freeze drying (FD). The resulting tissue structure of products processed with sequential infrared and freeze drying (SIRFD) tends to have higher crispness than those proce...

  3. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false LCV freeze; cargo-carrying unit freeze. 658.23 Section 658.23 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, WIDTH AND WEIGHT LIMITATIONS § 658.23 LCV freeze; cargo-carrying unit freeze....

  4. Seniors' Worsening Depression May Sometimes Predict Dementia

    MedlinePlus

    ... nlm.nih.gov/medlineplus/news/fullstory_158576.html Seniors' Worsening Depression May Sometimes Predict Dementia Study suggests ... In some cases, worsening symptoms of depression in seniors might point to early dementia, a new study ...

  5. Heat pump with freeze-up prevention

    DOEpatents

    Ecker, Amir L.

    1981-01-01

    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.

  6. Crystal structures and freezing of dipolar fluids.

    PubMed

    Groh, B; Dietrich, S

    2001-02-01

    We investigate the crystal structure of classical systems of spherical particles with an embedded point dipole at T=0. The ferroelectric ground state energy is calculated using generalizations of the Ewald summation technique. Due to the reduced symmetry compared to the nonpolar case the crystals are never strictly cubic. For the Stockmayer (i.e., Lennard-Jones plus dipolar) interaction three phases are found upon increasing the dipole moment: hexagonal, body-centered orthorhombic, and body-centered tetragonal. An even richer phase diagram arises for dipolar soft spheres with a purely repulsive inverse power law potential approximately r(-n). A crossover between qualitatively different sequences of phases occurs near the exponent n=12. The results are applicable to electro- and magnetorheological fluids. In addition to the exact ground state analysis we study freezing of the Stockmayer fluid by density-functional theory. PMID:11308482

  7. Freeze chromatography method and apparatus

    DOEpatents

    Scott, C.D.

    1987-04-16

    A freeze chromatography method and apparatus are provided which enable separation of the solutes contained in a sample. The apparatus includes an annular column construction comprising cylindrical inner and outer surfaces defining an annular passage therebetween. One of the surfaces is heated and the other cooled while passing an eluent through the annular passageway so that the eluent in contact with the cooled surface freezes and forms a frozen eluent layer thereon. A mixture of solutes dissolved in eluent is passed through the annular passageway in contact with the frozen layer so that the sample solutes in the mixture will tend to migrate either toward or away the frozen layer. The rate at which the mixture flows through the annular passageway is controlled so that the distribution of the sample solutes approaches that at equilibrium and thus a separation between the sample solutes occurs. 3 figs.

  8. The structure of the cytoplasmic matrix preserved by freeze-drying and freeze-substitution.

    PubMed

    Porter, K R; Anderson, K L

    1982-11-01

    This paper reports a study of the cytoplasmic matrix in whole cultured cells examined by high voltage electron microscopy. In order to acquaint ourselves with the influence of preparation procedures on the morphology depicted, PtK2 cells were prepared for examination by first freezing in propane at -185 degrees C and then drying while maintained at -95 degrees C. Other cells of the same type were first fixed with glutaraldehyde and OsO4 and then frozen dried. Others were prepared by freeze-substitution and eventually dried by the critical-point method from CO2. And finally, some were preserved by conventional techniques of glutaraldehyde and OsO4 followed by dehydration in alcohol and critical-point drying. The observations are presented in stereo images. The morphologies after these various procedures are quite similar. All show the characteristic three-dimensional lattice or meshwork of slender filaments called microtrabeculae. In cells rapidly frozen and then dried from the frozen state, there is less evidence of shrinkage and probable change in the trabecular structure than in cells first fixed with glutaraldehyde and then frozen dried. The differences we relate to the demonstrable failure of glutaraldehyde to penetrate the cell quickly and fix instantly any component that is in active motion. Other differences that can be observed between all four types of preparation are not recognizably striking and are thought to reflect as much as anything morphological diversity in the original cells. In some instances, the amorphous ice of the initial freezing at -185 degrees C was allowed to crystallize at -80 degrees C. The small crystals that form push aside the microtrabeculae and leave obvious imprints on the structure. The essential message from these experiments is that the cytomatrix is structured. PMID:6818029

  9. Freeze Technology for Nuclear Applications - 13590

    SciTech Connect

    Rostmark, Susanne C.; Knutsson, Sven; Lindberg, Maria

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Hamidi, Nurkholis; Tsuruta, Takaharu

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

  11. Repeated freezing induces oxidative stress and reduces survival in the freeze-tolerant goldenrod gall fly, Eurosta solidaginis.

    PubMed

    Doelling, Adam R W; Griffis, Nicole; Williams, Jason B

    2014-08-01

    Freeze tolerant insects must not only survive extracellular ice formation but also the generation of reactive oxygen species (ROS) during oxygen reperfusion upon thawing. Furthermore, diurnal fluctuations in temperature place temperate insects at risk of being exposed to multiple freeze-thaw cycles, yet few studies have examined metrics of survival and oxidative stress in freeze-tolerant insects subjected to successive freezing events. To address this, we assessed survival in larvae of the goldenrod gall fly Eurosta solidaginis, after being subjected to 0, 5, 10, 20, or 30 diurnally repeated cold exposures (RCE) to -18°C or a single freeze to -18°C for 20days. In addition, we measured indicators of oxidative stress, levels of cryoprotectants, and total aqueous antioxidant capacity in animals exposed to the above treatments at 8, 32, or 80h after their final thaw. Repeated freezing and thawing, rather than time spent frozen, reduced survival as only 30% of larvae subjected to 20 or 30 RCE successfully pupated, compared to those subjected to fewer RCE or a single 20d freeze, of which 82% pupated. RCE had little effect on the concentration of the cryoprotectant glycerol (4.26±0.66μgglycerol·ngprotein(-1) for all treatments and time points) or sorbitol (18.8±2.9μgsorbitol·mgprotein(-1) for all treatments and time points); however, sorbitol concentrations were more than twofold higher than controls (16.3±2.2μgsorbitol·mgprotein(-1)) initially after a thaw in larvae subjected to a single extended freeze, but levels returned to values similar to controls at 80h after thaw. Thawing likely produced ROS as total aqueous antioxidant capacities peaked at 1.8-fold higher than controls (14.7±1.6mmoltrolox·ngprotein(-1)) in animals exposed to 5, 10, or 20 RCE. By contrast, aqueous antioxidant capacities were similar to controls in larvae subjected to 30 RCE or the single 20d freeze regardless of time post final thaw, indicating these animals may have had an impaired ability to produce primary antioxidants. Larvae lacking an antioxidant response also had elevated levels of oxidized proteins, nearly twice that of controls (21.8±3.2mmolchloramine-T·mgprotein(-1)). Repeated freezing also lead to substantial oxidative damage to lipids that was independent of aqueous antioxidant capacity; peroxides were, on average, 5.6-fold higher in larvae subjected to 10, 20 or 30 RCE compared to controls (29.1±7.3mmolTMOP·μgprotein(-1)). These data suggest that oxidative stress due to repeated freeze-thaw cycles reduces the capacity of E. solidaginis larvae to survive freezing. PMID:24910457

  12. Depression - overview

    MedlinePlus

    Depression may be described as feeling sad, blue, unhappy, miserable, or down in the dumps. Most of ... one time or another for short periods. Clinical depression is a mood disorder in which feelings of ...

  13. Postpartum Depression

    MedlinePlus

    ... do not need treatment. The symptoms of postpartum depression last longer and are more severe. You may ... treatment right away, often in the hospital. Postpartum depression can begin anytime within the first year after ...

  14. Study on the Impurity Effect in the Realization of Silver Fixed Point

    NASA Astrophysics Data System (ADS)

    Tsai, S. F.

    2016-03-01

    The application of a thermal analysis model to estimate the temperature depression from the ideal fixed-point temperature is important, especially when the chemical analysis of the sample in a cell is insufficient or the cell might have been contaminated during fabrication. This study extends previous work, on thermal analysis with the tin point, to an investigation of the impurity dependence of the silver-point temperature. Close agreement was found between the temperature depression (-0.36 mK) inferred from the thermal analysis of the measured fixed-point plateau and the temperature depression (-0.32 mK) inferred using the sum of individual estimates (SIE) method with an impurity analysis based on glow discharge mass spectrometry. Additionally, the results of the thermal analysis manifest no significant dependence on the rate of solidification, and the scatter of observed gradients was within 0.36 mK among five plateaux with different temperature settings of the furnace. Although the results support the application of both the SIE method and thermal analysis for the silver point, further experiments with cell-to-cell comparisons linked to thermal analysis, a study of the thermometer-furnace systematic effects, the oxygen effect, and the locus of the freezing plateau should be investigated to reach a firm conclusion.

  15. Understanding Depression

    PubMed Central

    McNair, F. E.

    1981-01-01

    To understand the effects of depression on a patient's life, the physician must be aware how depression manifests itself. Somatic tension, strategies to relieve discomfort and social withdrawal must be recognized as symptoms of depression. An awareness of life situations which can give rise to these symptoms, as well as the effect of the physician's own reactions to the patient's depression, are helpful. PMID:21289767

  16. Childhood Depression.

    ERIC Educational Resources Information Center

    Venzke, Randell C.; And Others

    1987-01-01

    Childhood depression has only been accepted as an appropriate clinical diagnosis since the 1960s. Evidence suggests that depressive symptoms in children are difficult to reverse and may persist into adolescence and adult life if unsuccessfully treated. Discusses etiology, symptoms, assessment, and treatment of childhood depression. (Author/NB)

  17. Adolescent Depression.

    ERIC Educational Resources Information Center

    Evans, Dina M.

    Affective disorder is characterized by maladaptive changes in mood, attitudes, energy level, and physical status. These changes constitute the basic dimensions of depression. Depression results from a combination of genetic and experiential factors. There are sex differences and age differences with regard to depression, and there is a high…

  18. Perinatal depression

    PubMed Central

    Alhusen, Jeanne L.; Alvarez, Carmen

    2016-01-01

    Abstract: Perinatal depression is a common condition with significant adverse maternal, fetal, neonatal, and early childhood outcomes. The perinatal period is an opportune time to screen, diagnose, and treat depression. Improved recognition of perinatal depression, particularly among low-income women, can lead to improved perinatal health outcomes. PMID:26934457

  19. Metabolic activity of permafrost bacteria below the freezing point

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  20. Cavitation in water under tension near the freezing point

    SciTech Connect

    Sosikov, V. A. Utkin, A. V.; Fortov, V. E.

    2008-05-15

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

  1. Metabolic Activity of Permafrost Bacteria below the Freezing Point

    PubMed Central

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

    2000-01-01

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

  2. Tunable shape transformation of freezing liquid water marbles.

    PubMed

    Zang, Duyang; Lin, Kejun; Wang, Wenkai; Gu, Yaxi; Zhang, Yongjian; Geng, Xingguo; Binks, Bernard P

    2014-03-01

    Liquid water marbles coated with fumed silica nanoparticles exhibit various shape transformations upon freezing which are dependent on the hydrophobicity of the nanoparticles. The shape can be recovered during re-melting. For marbles coated with the most hydrophobic particles, a vertically prolonged morphology with a pointed protrusion on the top is formed on freezing. For marbles coated with less hydrophobic particles, a lateral expanded flying saucer-shaped morphology is formed. The different responses to freezing result from the different heterogeneous nucleation sites owing to the different positions of the particles at the air-water interface. If the particles are more immersed in water, ice embryos tend to form in the concave cavities between the particles. The volume expansion of water caused by freezing and continuous nucleation lead to continuous lateral stretching of the particle network coating the droplet surface and ultimately to the horizontally inflated shape of the marble. If the particles are more exposed to air, nucleation occurs on the convex surface of the particles, similar to that of a bare water droplet on a hydrophobic substrate. PMID:24651262

  3. Monte Carlo simulation of the OCP freezing transition

    SciTech Connect

    DeWitt, H.E.; Slattery, W.L.; Yang, Juxing

    1992-09-01

    The One Component Plasma (OCP) in three dimensions is a system of classical point charges moving in a fixed uniform neutralizing background. In nature the OCP is a rough approximation of the conditions in a white dwarf star in which one has fully ionized nuclei such as carbon, oxygen, and smaller amounts of heavier elements up to iron all moving in a nearly uniform background provided by relativistically degenerate electrons. The OCP is also a mathematical limiting model for a non-neutral plasma of ions in a Penning trap and cooled to strongly coupled conditions. Similarly, a collection of charge colloidal suspensions in water can exhibit the Coulomb freezing behavior of the OCP. A single dimensionless parameter, {Gamma} is sufficient to describe the system. For very weak coupling, {Gamma} {much_lt} 1, the thermodynamic properties of the OCP are given rigorously by the Debye-Huckel theory. This paper reports on Monte Carlo simulation of the freezing of the OCP from a random start for particle numbers ranging from 500 to 2000. In one case the authors obtained a perfect bcc lattice, but in most cases the final state would be an imperfect crystal or two different microcrystals, fcc and bcc, growing into each other. With a cluster analysis program the authors looked at the formation of nucleating clusters, and followed the actual freezing process. Roughly 80 particles are needed in a cluster before it starts to grow rapidly and freeze.

  4. Monte Carlo simulation of the OCP freezing transition

    SciTech Connect

    DeWitt, H.E. ); Slattery, W.L. ); Yang, J. . Dept. of Biological Chemistry and Molecular Pharmacology)

    1992-09-01

    The One Component Plasma (OCP) in three dimensions is a system of classical point charges moving in a fixed uniform neutralizing background. In nature the OCP is a rough approximation of the conditions in a white dwarf star in which one has fully ionized nuclei such as carbon, oxygen, and smaller amounts of heavier elements up to iron all moving in a nearly uniform background provided by relativistically degenerate electrons. The OCP is also a mathematical limiting model for a non-neutral plasma of ions in a Penning trap and cooled to strongly coupled conditions. Similarly, a collection of charge colloidal suspensions in water can exhibit the Coulomb freezing behaviour of the OCP. A single dimensionless parameter, [Gamma] is sufficient to describe the system. For very weak coupling, [Gamma][much lt]1, the thermodynamic properties of the OCP are given rigorously by the Debye-Huckel theory. This paper reports on Monte Carlo simulation of the freezing of the OCP from a random start for particle numbers ranging from 500 to 2000. In one case the authors obtained a perfect bcc lattice, but in most cases the final state would be an imperfect crystal or two different microcrystals, fcc and bcc, growing into each other. With a cluster analysis program the authors looked at the formation of nucleating clusters, and followed the actual freezing process. Roughly 80 particles are needed in a cluster before it starts to grow rapidly and freeze.

  5. Freeze-fracture of biological specimens prior to conductive staining.

    PubMed

    Iida, N

    1984-03-01

    Liver, kidney, spleen and other organs of the rat were fixed with glutaraldehyde, substituted with absolute ethanol or dimethyl sulfoxide (DMSO), freeze-fractured in liquid nitrogen, stained by the rapid tannin-osmium thiocarbohydrazide-osmium (TaOTO) method (staining with each agent for 10 min), critical-point-dried with liquid carbon dioxide, and observed with the scanning electron microscope. The absolute ethanol or DMSO freeze-fracture method provided flat fracture surfaces (without regard to cell boundaries) of the samples and allowed a good visualization of their inner structures. The fracture surfaces were suitably stained by the rapid TaOTO method, and could be scanned with no charging. Neither maked damage nor undesired dislocation of tissue elements was noted on the freeze-fractured and TaOTO-stained surfaces. This procedure, freeze-fracture prior to conductive staining, has an advantage of eliminating the bulk charging effects that tend to occur in specimens fractured after staining. When substituted with 75% DMSO aqueous solution, the samples spontaneously fractured without any need for razor blades. Fracture planes in this spontaneous fracture sometimes ran along the cell boundaries and allowed a clear visualization in the SEM of the enfaced surfaces of closely associated cells such as hepatocytes. PMID:6204620

  6. Updating freeze: aligning animal and human research.

    PubMed

    Hagenaars, Muriel A; Oitzl, Melly; Roelofs, Karin

    2014-11-01

    Freezing is widely used as the main outcome measure for fear in animal studies. Freezing is also getting attention more frequently in human stress research, as it is considered to play an important role in the development of psychopathology. Human models on defense behavior are largely based on animal models. Unfortunately, direct translations between animal and human studies are hampered by differences in definitions and methods. The present review therefore aims to clarify the conceptualization of freezing. Neurophysiological and neuroanatomical correlates are discussed and a translational model is proposed. We review the upcoming research on freezing in humans that aims to match animal studies by using physiological indicators of freezing (bradycardia and objective reduction in movement). Finally, we set the agenda for future research in order to optimize mutual animal-human translations and stimulate consistency and systematization in future empirical research on the freezing phenomenon. PMID:25108035

  7. Depressive Disorders During Pregnancy

    PubMed Central

    Melville, Jennifer L.; Gavin, Amelia; Guo, Yuqing; Fan, Ming-Yu; Katon, Wayne J.

    2011-01-01

    OBJECTIVE To estimate the prevalence of major and minor depression, panic disorder, and suicidal ideation during pregnancy while also identifying factors independently associated with antenatal depressive disorders. METHODS In this prospective study, participants were 1,888 women receiving ongoing prenatal care at a university obstetric clinic from January 2004 through January 2009. Prevalence of psychiatric disorders was measured using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria based on the Patient Health Questionnaire. Multiple logistic regression identified factors associated with probable major depressive disorder and any depressive disorder. RESULTS Antenatal depressive disorders were present in 9.9% with 5.1% (97) meeting criteria for probable major depression and 4.8% (90) meeting criteria for probable minor depression. Panic disorder was present in 3.2% (61), and current suicidal ideation was reported by 2.6% (49). Among patients with probable major depression, 29.5% (28) reported current suicidal ideation. Psychosocial stress (odds ratio [OR], 1.29; 95% confidence interval [CI], 1.21–1.36), domestic violence (OR 3.45; 95% CI 1.46–8.12), chronic medical conditions (OR 3.05; 95% CI 1.63–5.69), and race (Asian: OR 5.81; 95% CI 2.55–13.23; or African American: OR 2.98; 95% CI 1.24–7.18) each significantly increased the odds of probable antepartum major depressive disorder, whereas older age (OR 0.92; 95% CI 0.88–0.97) decreased the odds. Factors associated with odds of any depression were similar overall except that Hispanic ethnicity (OR 2.50; 95% CI 1.09–5.72) also independently increased the odds of any depression. CONCLUSION Antenatal major and minor depressive disorders are common and significantly associated with clinically relevant and identifiable risk factors. By understanding the high point prevalence and associated factors, clinicians can potentially improve the diagnosis and treatment rates of serious depressive disorders in pregnant women. PMID:20966690

  8. Predicting Freezing for Some Repulsive Potentials

    SciTech Connect

    Khrapak, S. A.; Morfill, G. E.

    2009-12-18

    We propose a simple method to approximately predict the freezing (fluid-solid) phase transition in systems of particles interacting via purely repulsive potentials. The method is based on the striking universality of the freezing curve for the model Yukawa and inverse-power-law interactions. This method is applied to draw an exemplary phase diagram of complex plasmas. We suggest that it can also be used to locate freezing transition in other substances with similar properties of interaction.

  9. Egg freezing: a breakthrough for reproductive autonomy?

    PubMed

    Harwood, Karey

    2009-01-01

    This article describes the relatively new technology of freezing human eggs and examines whether egg freezing, specifically when it is used by healthy women as 'insurance' against age-related infertility, is a legitimate exercise of reproductive autonomy. Although egg freezing has the potential to expand women's reproductive options and thus may represent a breakthrough for reproductive autonomy, I argue that without adequate information about likely outcomes and risks, women may be choosing to freeze their eggs in a commercially exploitative context, thus undermining rather than expanding reproductive autonomy. PMID:18945249

  10. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    EPA Science Inventory

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  11. Additional weight load increases freezing of gait episodes in Parkinson's disease; an experimental study.

    PubMed

    Mensink, Senja H G; Nonnekes, Jorik; van Bon, Geert; Snijders, Anke H; Duysens, Jacques; Weerdesteyn, Vivian; Bloem, Bastiaan R; Oude Nijhuis, Lars B

    2014-05-01

    Freezing of gait is an episodic gait disorder,characterized by the inability to generate effective forward stepping movements. The pathophysiology underlying freezing of gait remains insufficiently understood, and this hampers the development of better treatment strategies.Preliminary evidence suggests that impaired force control during walking may contribute to freezing episodes, with difficulty to unload the swing leg and initiate the swing phase. Here, we used external loading to manipulate force control and to investigate its influence on freezing of gait.Twelve Parkinson's disease patients with freezing of gait performed three contrasting tasks: (1) loaded gait while wearing a belt fortified with lead weights; (2) weight supported gait using a parachute harness connected to a rigid metal cable running above the gait trajectory; and (3)normal gait. Gait tasks were used to provoke freezing episodes, including rapid 360° turns. Freezing episodes were quantified using blinded, videotaped clinical assessment. Furthermore, ground reaction forces and body kinematics were recorded. Loading significantly increased the mean number of freezing episodes per trial compared to the normal gait condition (P<0.05), but the effect of weight support was not consistent. Loading particularly increased the number of freezing episodes during rapid short steps. Step length was significantly smaller during loaded gait compared to normal gait (P<0.05), but changes in anticipatory postural adjustments were not different.Our results may point to impaired force control playing a key role in freezing of gait. Future studies should further investigate the mechanism, i.e., the contribution of deficient load feedback, and evaluate which forms of weight support might offer treatment opportunities. PMID:24658705

  12. Mechanisms of deterioration of nutrients. [of freeze dried foods

    NASA Technical Reports Server (NTRS)

    Karel, M.; Flink, J. M.

    1976-01-01

    Methods which produce freeze dried foods of improved quality were examined with emphasis on storage stability. Specific topics discussed include: microstructure of freeze dried systems, investigation of structural changes in freeze dried systems, artificial food matrices, osmotic preconcentration to yield improved quality freeze dried fruits, and storage stability of osmotically preconcentrated freeze dried fruits.

  13. Urban Modification of Freezing-Rain Events.

    NASA Astrophysics Data System (ADS)

    Changnon, Stanley A.

    2003-06-01

    A new national database for freezing-rain occurrences during the 1945-2000 period provided an opportunity for a study of the potential urban effects on freezing-rain events. Numerous past studies of snowfall events in urban areas have defined decreases of 10%-35% related to the urban heat island. The heat island, which acts to elevate near-surface temperatures, could also keep some freezing-rain situations from occurring in the city. The study involved four cities in the Midwest and Northeast for which the average annual number of days with freezing rain are three or more, for which data from in-city stations existed, and for which data for several surrounding rural stations existed. The two largest qualifying cities, New York City, New York, and Chicago, Illinois, had sizable reductions in average and maximum annual freezing-rain-day frequencies, ranging from 16% to 43% less than values of surrounding rural stations, and their freezing-rain `seasons' were 1-2 months shorter than those in surrounding rural areas. The ocean/lake influences at both cities, along with the heat island, also helped to reduce the local incidence of freezing-rain events. Two qualifying smaller urban areas, Washington, District of Columbia, and St. Louis, Missouri, had reductions in freezing-rain-day occurrences but had no shifts in the length of their freezing-rain seasons. Results suggest that freezing-rain occurrences in large cities are decreased between 10% and 30% by the heat island, which acts to keep rain from freezing to urban surfaces.

  14. Geriatric Depression in Primary Care

    PubMed Central

    Park, Mijung; Unützer, Jürgen

    2011-01-01

    Primary care settings present important opportunities for the detection and management of depression in older adults. As many as 10 % of older adults presenting in primary care have clinically significant depression, but only about half are recognized and only one in five depressed older adults receive effective treatment in primary care. We review common barriers to effective treatment such as atypical clinical presentations and comorbid medical conditions that are common in older adults. We identify treatment strategies such as measurement-based stepped care and collaborative care that can substantially improve the effectiveness of treatment in this setting and we highlight opportunities for addressing health disparities in geriatric depression care. We also point out the importance of engaging and supporting family caregivers of depressed older adults. We conclude by identifying three strategic areas to improve the treatment of geriatric depression in primary care: activation and engagement of patients and family members, health care provider training, and broader system changes. PMID:21536169

  15. Avoiding gas bubble formation during freeze substitution.

    PubMed

    Fisher, D B

    1991-01-01

    Gas bubbles frequently are formed during freeze substitution, especially when tissues are warmed to room temperature. The problem arises largely from the extreme solubility of CO2 in the freeze substitution solvent. Gas bubbles may be minimized by briefly transferring the tissue to freshly chilled solvent before warming to room temperature. PMID:1790241

  16. A Simple Method for Quick-Freezing

    PubMed Central

    BEARER, ELAINE L.; ORCI, LELIO

    2015-01-01

    In conventional freeze-fracture replicas produced from tissue cryoprotected with glycerol, the hydrophobic inner surfaces of membranes are revealed, but hydrophillic structures are obscured in the surrounding ice. Quick-freezing of tissue obviates the need for glycerol, which prevents the removal of this ice by etching or freeze-drying, but the major problem in freezing without glycerol cryoprotection is ice crystal formation. We describe here a simple method for quick-freezing tissue, in the absence of glycerol, on a nitrogen-cooled copper block with a hand-held specimen holder. This method freezes samples well enough to preserve molecular detail that can be revealed by subsequent etching. We show some examples of the quality of this freezing with respect to the visualization of molecular detail in isolated protein molecules such as ferritin and catalase. Furthermore, we show examples of in situ cellular structures that are revealed by this method, and we compare the structure seen in these replicas with structures preserved by quick-freezing at liquid helium temperatures. PMID:26549928

  17. Inherent freeze protection for solar water heaters

    SciTech Connect

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

    1981-05-01

    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.

  18. HOST CADAVERS PROTECT ENTOMOPATHOGENIC NEMATODES DURING FREEZING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four species of insect-killing nematodes were exposed to freezing temperatures while inside their hosts. Survival was assessed by observing live and dead nematodes inside cadavers and by counting the infective juveniles (IJs) tht emerged after freezing. We 1) measured the effects of 24 hours of fr...

  19. Bioinspired Design: Magnetic Freeze Casting

    NASA Astrophysics Data System (ADS)

    Porter, Michael Martin

    Nature is the ultimate experimental scientist, having billions of years of evolution to design, test, and adapt a variety of multifunctional systems for a plethora of diverse applications. Next-generation materials that draw inspiration from the structure-property-function relationships of natural biological materials have led to many high-performance structural materials with hybrid, hierarchical architectures that fit form to function. In this dissertation, a novel materials processing method, magnetic freeze casting, is introduced to develop porous scaffolds and hybrid composites with micro-architectures that emulate bone, abalone nacre, and other hard biological materials. This method uses ice as a template to form ceramic-based materials with continuously, interconnected microstructures and magnetic fields to control the alignment of these structures in multiple directions. The resulting materials have anisotropic properties with enhanced mechanical performance that have potential applications as bone implants or lightweight structural composites, among others.

  20. Depression among Asian Americans: Review and Recommendations

    PubMed Central

    Kalibatseva, Zornitsa; Leong, Frederick T. L.

    2011-01-01

    This article presents a review of the prevalence and manifestation of depression among Asian Americans and discusses some of the existing issues in the assessment and diagnosis of depression among Asian Americans. The authors point out the diversity and increasing numbers of Asian Americans and the need to provide better mental health services for this population. While the prevalence of depression among Asian Americans is lower than that among other ethnic/racial groups, Asian Americans receive treatment for depression less often and its quality is less adequate. In addition, the previous belief that Asians somatize depression may become obsolete as more evidence appears to support that Westerners may “psychologize” depression. The cultural validity of the current DSM-IV conceptualization of depression is questioned. In the course of the review, the theme of complexity emerges: the heterogeneity of ethnic Asian American groups, the multidimensionality of depression, and the intersectionality of multiple factors among depressed Asian Americans. PMID:21961060

  1. Homogeneous freezing nucleation of stratospheric solution droplets

    NASA Technical Reports Server (NTRS)

    Jensen, Eric J.; Toon, Owen B.; Hamill, Patrick

    1991-01-01

    The classical theory of homogeneous nucleation was used to calculate the freezing rate of sulfuric acid solution aerosols under stratospheric conditions. The freezing of stratospheric aerosols would be important for the nucleation of nitric acid trihydrate particles in the Arctic and Antarctic stratospheres. In addition, the rate of heterogeneous chemical reactions on stratospheric aerosols may be very sensitive to their state. The calculations indicate that homogeneous freezing nucleation of pure water ice in the stratospheric solution droplets would occur at temperatures below about 192 K. However, the physical properties of H2SO4 solution at such low temperatures are not well known, and it is possible that sulfuric acid aerosols will freeze out at temperatures ranging from about 180 to 195 K. It is also shown that the temperature at which the aerosols freeze is nearly independent of their size.

  2. Depressive symptoms in neurodegenerative diseases.

    PubMed

    Baquero, Miquel; Martín, Nuria

    2015-08-16

    Depressive symptoms are very common in chronic conditions. This is true so for neurodegenerative diseases. A number of patients with cognitive decline and dementia due to Alzheimer's disease and related conditions like Parkinson's disease, Lewy body disease, vascular dementia, frontotemporal degeneration amongst other entities, experience depressive symptoms in greater or lesser grade at some point during the course of the illness. Depressive symptoms have a particular significance in neurological disorders, specially in neurodegenerative diseases, because brain, mind, behavior and mood relationship. A number of patients may develop depressive symptoms in early stages of the neurologic disease, occurring without clear presence of cognitive decline with only mild cognitive deterioration. Classically, depression constitutes a reliable diagnostic challenge in this setting. However, actually we can recognize and evaluate depressive, cognitive or motor symptoms of neurodegenerative disease in order to establish their clinical significance and to plan some therapeutic strategies. Depressive symptoms can appear also lately, when the neurodegenerative disease is fully developed. The presence of depression and other neuropsychiatric symptoms have a negative impact on the quality-of-life of patients and caregivers. Besides, patients with depressive symptoms also tend to further decrease function and reduce cognitive abilities and also uses to present more affected clinical status, compared with patients without depression. Depressive symptoms are treatable. Early detection of depressive symptoms is very important in patients with neurodegenerative disorders, in order to initiate the most adequate treatment. We review in this paper the main neurodegenerative diseases, focusing in depressive symptoms of each other entities and current recommendations of management and treatment. PMID:26301229

  3. Depressive symptoms in neurodegenerative diseases

    PubMed Central

    Baquero, Miquel; Martín, Nuria

    2015-01-01

    Depressive symptoms are very common in chronic conditions. This is true so for neurodegenerative diseases. A number of patients with cognitive decline and dementia due to Alzheimer’s disease and related conditions like Parkinson’s disease, Lewy body disease, vascular dementia, frontotemporal degeneration amongst other entities, experience depressive symptoms in greater or lesser grade at some point during the course of the illness. Depressive symptoms have a particular significance in neurological disorders, specially in neurodegenerative diseases, because brain, mind, behavior and mood relationship. A number of patients may develop depressive symptoms in early stages of the neurologic disease, occurring without clear presence of cognitive decline with only mild cognitive deterioration. Classically, depression constitutes a reliable diagnostic challenge in this setting. However, actually we can recognize and evaluate depressive, cognitive or motor symptoms of neurodegenerative disease in order to establish their clinical significance and to plan some therapeutic strategies. Depressive symptoms can appear also lately, when the neurodegenerative disease is fully developed. The presence of depression and other neuropsychiatric symptoms have a negative impact on the quality-of-life of patients and caregivers. Besides, patients with depressive symptoms also tend to further decrease function and reduce cognitive abilities and also uses to present more affected clinical status, compared with patients without depression. Depressive symptoms are treatable. Early detection of depressive symptoms is very important in patients with neurodegenerative disorders, in order to initiate the most adequate treatment. We review in this paper the main neurodegenerative diseases, focusing in depressive symptoms of each other entities and current recommendations of management and treatment. PMID:26301229

  4. Freeze-drying for morphological control of high performance semi-interpenetrating polymer networks. III

    NASA Technical Reports Server (NTRS)

    Hsiung, H. J.; Hansen, M. G.; Pater, R. H.

    1991-01-01

    The feasibility of using a freeze-drying (solvent removal by sublimation) approach for controlling the morphology of a high-performance semi-IPN is assessed. A high-performance thermoplastic polyimide and commercially available 4,4'-bismaleimide diphenylenemethane were dissolved in a solvent, 1,3,5-trioxane. The solvent was removed from the constituents by freeze-drying. For purposes of comparison, the constituents were dissolved in a high-boiling-point solvent, N,N-dimethylformamide. The solvent was removed from the solution by evaporation. The physical and mechanical properties and phase morphology of the neat resins and composites prepared by freeze-drying and traditional solution methods are presented and compared. It is concluded that the TG is higher and that the magnitude of minor constituent separation is less in the freeze-dry processed materials than for the processed solution.

  5. Microphysical Modelling of the 1999-2000 Arctic Winter. 3; Impact of Homogeneous Freezing on PSCs

    NASA Technical Reports Server (NTRS)

    Drdla, K.

    2003-01-01

    Simulations of the 1999-2000 winter have tested the effect on polar stratospheric clouds (PSCs) of the homogeneous freezing of liquid ternary solutions into nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD). Proposed laboratory-derived volume-based and surface-based homogeneous freezing rates have both been examined, including different assumptions about the extrapolation of laboratory measurements to atmospheric conditions. Widespread PSC formation and denitrification are possible in several of the scenarios examined. However, the simulations are all unable to explain the solid-phase PSCs observed early in the 1999-2000 winter, and are unable to reproduce the measured extent of vortex denitrification. These problems can both be attributed to the relatively cold temperatures, more than 5 K below the NAT condensation point, necessary for effective homogeneous freezing. Therefore synoptic-scale homogeneous freezing appears unlikely to be the primary mechanism responsible for solid-phase PSC formation.

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

    PubMed

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

    2014-01-21

    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

  7. A Phase-Field Solidification Model of Almost Pure ITS-90 Fixed Points

    NASA Astrophysics Data System (ADS)

    Large, M. J.; Pearce, J. V.

    2014-07-01

    A two-dimensional axisymmetric phase-field model of thermo-solutal solidification in freezing-point cells used for calibrating standard platinum resistance thermometers for realization and dissemination of the International Temperature Scale of 1990 is presented. The cell is essentially a graphite crucible containing an ingot of very pure metal (of order 99.9999 %). A graphite tube is inserted along the axis of the ingot to enable immersion of the thermometer in the metal. In this study, the metal is tin (freezing temperature of ). During the freezing of these cells, a steady, reproducible temperature is realized, with a defined temperature that can be used to calibrate thermometers with uncertainties mK. The model is applied to understand the effect of experimental parameters, such as initiation technique and furnace homogeneity, on the measured freezing curve. Results show that freezing curves whose behavior is consistent with the Scheil theory of solidification can be obtained with a specific furnace temperature profile, and provided that the freeze is of a long duration, the results are consistent with previous one-dimensional models and experiments. Morphological instability is observed with the inner interface initiation technique, causing the interface to adopt a cellular structure. This elevates the measured temperature, in accordance with the Gibbs-Thomson effect. In addition, the influence of initiation techniques on the solidification behavior is examined. The model indicates that an initially smooth inner mantle can `de-wet' from the thermometer well-forming agglomerated solid droplets, following recalescence, under certain conditions. This manifests as a measured temperature depression due to the Gibbs-Thomson effect, with a magnitude of to in simulations. The temperature rises to that of the stable outer mantle as freezing progresses and the droplets re-melt. It is demonstrated that the effect occurs below a critical mantle thickness. A physical explanation for the origin of the effect is offered showing that it is consistent with solid-state de-wetting phenomena. Consideration is also given to the limitations of the current model configuration.

  8. Exploring the Nature of Contact Freezing

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  9. Spray-freezing freeze substitution (SFFS) of cell suspensions for improved preservation of ultrastructure.

    PubMed

    Fields, S D; Strout, G W; Russell, S D

    1997-08-01

    Some unicellular organisms present challenges to chemical fixations that lead to common, yet obvious, artifacts. These can be avoided in entirety by adapting spray-freezing technology to ultrarapidly freeze specimens for freeze substitution. To freeze specimens, concentrated suspensions of cells ranging in diameter from 0.5-30 pm were sprayed with an airbrush at 140-200 kPa (1.05-1.5 torr; 20.3-29.0 psi) into a nylon mesh transfer basket submerged in liquid propane. After freezing, the mesh basket containing the frozen sample was lifted out of the chamber, drained and transferred through several anhydrous acetone rinses at 188 K (-85 degrees C). Freeze substitution was conducted in 1% tannic acid/1% anhydrous glutaraldehyde in acetone at 188 K (-85 degrees C), followed by 1% OsO4/acetone at 277 K (4 degrees C). Freeze substitution was facilitated using a shaking table to provide gentle mixing of the substitution medium on dry ice. High quality freezing was observed in 70% of spray-frozen dinoflagellate cells and in 95% of spray-frozen cyanobacterial cells. These could be infiltrated and observed directly; however, overall ultrastructural appearance and membrane contrast were improved when the freeze-substituted cells were rehydrated and post-fixed in aqueous OSO4, then dehydrated and embedded in either Spurr's or Epon resin. Ultrastructural preservation using this ultrarapid freezing method provided specimens that were consistently superior to those obtainable in even the best comparable chemical fixations. PMID:9264343

  10. Immersion freezing of different kinds of combustion ashes

    NASA Astrophysics Data System (ADS)

    Augustin-Bauditz, Stefanie; Grawe, Sarah; Hellner, Lisa; Wex, Heike; Pettersson, Jan B. C.; Stratmann, Frank

    2015-04-01

    Ice particles in the atmosphere influence both, weather and climate. Therefore it is important to know which kind of particles can act as ice nucleating particles (INP) under atmospheric conditions. In the last years, a lot of effort has been made to investigate the freezing abilities of natural INPs such as dusts and biological particles (Murray et al., 2012, Hoose and Möhler, 2012). However, there are only a few investigations concerning the ice nucleation ability of combustion ashes, which are the remains of fossil fuel and wood combustion and thus a possible source for anthropogenic INPs. Ash particles have similar compositions as mineral dust particles. However, the actual contribution of combustion ash particles to the atmospheric ice nucleation is rather unclear. A recent study by Umo et al. (2014) showed that combustion ashes could have a significant impact on the ice nucleation in clouds and thus should be the focus of further research. Ash particles can be lifted to the atmosphere by wind (bottom ashes) or directly during the combustion process (fly ashes). In the present study we investigated the freezing behavior of bottom ash particles which originated from wood as well as from coal. Additionally we investigated particles from fly ash from a coal-fired power plant. Particles were generated by dry dispersion and afterwards size selected with a differential mobility analyzer (DMA). The immersion freezing ability of the different ash particles was quantified utilizing the Leipzig Aerosol Cloud Interaction Simulator (LACIS, Hartmann et al., 2011), where exactly one size segregated ash particle is immersed in a droplet. We found significant differences between the freezing abilities of the different ash types. Particles from wood bottom ashes initiate freezing at rather low temperatures near the homogenous freezing point (around -36°C). Particles from coal bottom ashes show significant higher ice nucleation abilities than the wood bottom ash, with observed freezing temperatures similar to those of clay minerals (around -30°C). The particles from the fly ash showed the best freezing ability, which was significantly higher than the freezing ability of the clay minerals but still not as good as that of K-feldspar. Hartmann, S., Niedermeier, D., Voigtländer, J., Clauss, T., Shaw, R. A., Wex, H., Kiselev, A., and Stratmann, F.: Atmos. Chem. Phys., 11, 1753-1767, doi:10.5194/acp-11-1753-2011, 2011. Hoose, C. and O. Möhler, Atmos. Chem. Phys., 12, 9817-9854, 2012. Murray, B. J., O'Sullivan, D., Atkinson, J. D. and Webb, M. E., Chem. Soc. Rev., 41, 6519-6554, 2012. Umo N. S., Murray B. J., Baeza-Romero M. T., Jones J. M., Lea-Langton A. R., Malkin T. L., O'Sullivan D., Plane J. M. C. and Williams A., Atmos. Chem. Phys. Discuss., 14, 28845-28883, 2014

  11. New particle dependant parameterizations of heterogeneous freezing processes.

    NASA Astrophysics Data System (ADS)

    Diehl, Karoline; Mitra, Subir K.

    2014-05-01

    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.

  12. Freeze Denaturation of Fish Muscle Proteins

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Takahide

    Studies on the freeze denaturation of fish muscle proteins were reviewed with emphasis given to changes in their physicochemical and biochemical properties during frozen storage. Denaturation of actomyosin commonly occurs during frozen storage and side-to-side aggregation of myosin molecules apppears to major role in this reaction. The author's group performed freezing studies with isolated preparations of proteins from carp muscle, namely actomyosin, myosin, H-meromyosin, L-meromyosin, and actin. Freeze denaturation occurred with indvidual proteins as well as with their subunits. Not only aggregation but also some conformational changes were observed. Denaturation was inhibited in the presence of added glutamate.

  13. Monitoring the freeze-thaw process of soil with different moisture contents using piezoceramic transducers

    NASA Astrophysics Data System (ADS)

    Wang, Ruolin; Zhu, Daopei; Liu, Xiaoyan; Sima, Jun

    2015-05-01

    Water content plays an active and important role in the performance of the soil freeze-thaw cycle to form frozen soil mechanical properties. Monitoring the freeze-thaw cycle of soil with various types of soil with varied moisture content will provide a direct observation of the properties of soil in cold regions. This paper presents new findings from monitoring the freeze-thaw process of soil using a piezoceramic-based smart aggregate (SA). For comparison, clay soil and medium sand with different moisture contents were used to study the behavior of the soil under the freeze-thaw process. Two SAs were embedded in the soil specimens with a pre-determined distance between them, one as an actuator to generate a stress wave and the other as a sensor to detect the propagated wave. As the propagation of the emitted wave is sensitive to soil status and properties, it is possible to monitor the soil freeze-thaw process by interpreting the SA sensor signal. Based on the attenuation of the energy, a freeze-thaw status indicator was established to describe the freezing-thawing condition. Indicator values of soil specimens with different types and different levels of moisture in freeze-thaw cycles were studied. The test results indicate that the freezing duration in the freezing-thawing process varied for different types of soil and different initial moisture content of the soil. Soil with different particle sizes and moisture content will determine the frozen soil microstructure and its corresponding mechanical properties. Our results illustrate that if soil particle size is bigger, then the signal indicator is stronger; if the moisture content is higher for the same soil, then the signal indicator is stronger. The research presents an innovative method to investigate the freezing-thawing performance of soil and potentially points to a new method to study the variation of soil mechanical properties during the freezing-thawing process, which is a critical problem for infrastructure in cold regions.

  14. Freeze concentration beats the heat

    SciTech Connect

    Rosen, J.

    1990-12-01

    This paper reports on freeze concentration (FC) which saves energy and money in packaging, shipping, and storing food products. FC---in contrast to existing heat-evaporation processes---retains volatile flavor and aroma compounds in food products so that no additives are required to restore the taste and smell of the original product. In recent tests on orange, grapefruit, and pineapple juices, reconstituted FC juices were found to be superior in taste to juices produced by evaporation and similar to the original pasteurized juices. The dairy industry, which is the largest user of energy for concentration in the food sector, is looking to FC for new products such as frozen concentrated milk as well as better use of the milk by-products of cheese production. The biggest potential for new FC applications is in those industries that consume large amounts of energy for separation processing, according to a 1987 report prepared for EPRI. In the food industry, this includes milk, vinegar, and beer producers. Potential applications also abound in the pulp and paper, pharmaceutical, chemical, and petroleum industries. FC separates substances via crystallization at substantial energy savings.

  15. Myofascial trigger point pain.

    PubMed

    Jaeger, Bernadette

    2013-01-01

    Myofascial trigger point pain is an extremely prevalent cause of persistent pain disorders in all parts of the body, not just the head, neck, and face. Features include deep aching pain in any structure, referred from focally tender points in taut bands of skeletal muscle (the trigger points). Diagnosis depends on accurate palpation with 2-4 kg/cm2 of pressure for 10 to 20 seconds over the suspected trigger point to allow the referred pain pattern to develop. In the head and neck region, cervical muscle trigger points (key trigger points) often incite and perpetuate trigger points (satellite trigger points) and referred pain from masticatory muscles. Management requires identification and control of as many perpetuating factors as possible (posture, body mechanics, psychological stress or depression, poor sleep or nutrition). Trigger point therapies such as spray and stretch or trigger point injections are best used as adjunctive therapy. PMID:24864393

  16. Adolescent Depression

    PubMed Central

    Cook, Mary N.; Peterson, John; Sheldon, Christopher

    2009-01-01

    Depression in adolescence and adulthood is common, afflicting up to 20 percent of these populations. It represents a significant public health concern and is associated with considerable suffering and functional impairment. Adolescent-onset depression tends to be a particularly malignant and recalcitrant condition, increasing the likelihood of recurrence and chronicity in adulthood. Clinical presentations for various medical and psychiatric conditions, as well as reactions to psychosocial stressors, can mimic or confound the picture of depression in adolescents. Therefore, careful assessment and differential diagnosis is essential. Effective treatments, both pharmacological and psychosocial in nature, exist, and so early detection and intervention is paramount. This article presents an overview of optimal prevention, assessment, and clinical decision-making strategies for managing depression in adolescents. PMID:19855857

  17. Postpartum Depression

    MedlinePlus

    ... Women with postpartum depression have intense feelings of sadness, anxiety, or despair that prevent them from being ... of female reproductive organs. Postpartum Blues: Feelings of sadness, fear, anger, or anxiety occurring about 3 days ...

  18. Evaluation of spin freezing versus conventional freezing as part of a continuous pharmaceutical freeze-drying concept for unit doses.

    PubMed

    De Meyer, L; Van Bockstal, P-J; Corver, J; Vervaet, C; Remon, J P; De Beer, T

    2015-12-30

    Spin-freezing as alternative freezing approach was evaluated as part of an innovative continuous pharmaceutical freeze-drying concept for unit doses. The aim of this paper was to compare the sublimation rate of spin-frozen vials versus traditionally frozen vials in a batch freeze-dryer, and its impact on total drying time. Five different formulations, each having a different dry cake resistance, were tested. After freezing, the traditionally frozen vials were placed on the shelves while the spin-frozen vials were placed in aluminum vial holders providing radial energy supply during drying. Different primary drying conditions and chamber pressures were evaluated. After 2h of primary drying, the amount of sublimed ice was determined in each vial. Each formulation was monitored in-line using NIR spectroscopy during drying to determine the sublimation endpoint and the influence of drying conditions upon total drying time. For all tested formulations and applied freeze-drying conditions, there was a significant higher sublimation rate in the spin-frozen vials. This can be explained by the larger product surface and the lower importance of product resistance because of the much thinner product layers in the spin frozen vials. The in-line NIR measurements allowed evaluating the influence of applied drying conditions on the drying trajectories. PMID:25981618

  19. Automated Assessment of Pavlovian Conditioned Freezing and Shock Reactivity in Mice Using the Video Freeze System

    PubMed Central

    Anagnostaras, Stephan G.; Wood, Suzanne C.; Shuman, Tristan; Cai, Denise J.; LeDuc, Arthur D.; Zurn, Karl R.; Zurn, J. Brooks; Sage, Jennifer R.; Herrera, Gerald M.

    2009-01-01

    The Pavlovian conditioned freezing paradigm has become a prominent mouse and rat model of learning and memory, as well as of pathological fear. Due to its efficiency, reproducibility and well-defined neurobiology, the paradigm has become widely adopted in large-scale genetic and pharmacological screens. However, one major shortcoming of the use of freezing behavior has been that it has required the use of tedious hand scoring, or a variety of proprietary automated methods that are often poorly validated or difficult to obtain and implement. Here we report an extensive validation of the Video Freeze system in mice, a “turn-key” all-inclusive system for fear conditioning in small animals. Using digital video and near-infrared lighting, the system achieved outstanding performance in scoring both freezing and movement. Given the large-scale adoption of the conditioned freezing paradigm, we encourage similar validation of other automated systems for scoring freezing, or other behaviors. PMID:20953248

  20. Microbial analysis and survey test of gamma-irradiated freeze-dried fruits for patient's food

    NASA Astrophysics Data System (ADS)

    Park, Jae-Nam; Sung, Nak-Yun; Byun, Eui-Hong; Byun, Eui-Baek; Song, Beom-Seok; Kim, Jae-Hun; Lee, Kyung-A.; Son, Eun-Joo; Lyu, Eun-Soon

    2015-06-01

    This study examined the microbiological and organoleptic qualities of gamma-irradiated freeze-dried apples, pears, strawberries, pineapples, and grapes, and evaluated the organoleptic acceptability of the sterilized freeze-dried fruits for hospitalized patients. The freeze-dried fruits were gamma-irradiated at 0, 1, 2, 3, 4, 5, 10, 12, and 15 kGy, and their quality was evaluated. Microorganisms were not detected in apples after 1 kGy, in strawberries and pears after 4 kGy, in pineapples after 5 kGy, and in grapes after 12 kGy of gamma irradiation. The overall acceptance score, of the irradiated freeze-dried fruits on a 7-point scale at the sterilization doses was 5.5, 4.2, 4.0, 4.1, and 5.1 points for apples, strawberries, pears, pineapples, and grapes, respectively. The sensory survey of the hospitalized cancer patients (N=102) resulted in scores of 3.8, 3.7, 3.9, 3.9, and 3.7 on a 5-point scale for the gamma-irradiated freeze-dried apples, strawberries, pears, pineapples, and grapes, respectively. The results suggest that freeze-dried fruits can be sterilized with a dose of 5 kGy, except for grapes, which require a dose of 12 kGy, and that the organoleptic quality of the fruits is acceptable to immuno-compromised patients. However, to clarify the microbiological quality and safety of freeze-dried fruits should be verified by plating for both aerobic and anaerobic microorganisms.

  1. [Freezing and gait disorders in Parkinson's disease].

    PubMed

    Gonçalves, Giovanna; Pereira, João

    2013-06-01

    More than one third of patients with Parkinson disease experience freezing. It is characterized by the feeling that one's feet are "glued to the floor", and it is more common in the later stages of the disease. The causes of this gait disorder are not yet fully established, but it may lead patients to suffer falls and lose their independence. As a consequence, the development of therapeutic measures which can overcome freezing is of fundamental important for the autonomy of such individuals. There is no consensus in the literature on the most recommended therapeutic measures for the prevention or attenuation of freezing in gait. What seems to be defined are the phenomenological aspects of the disorder and good therapy, represented by the association between drug therapy and sensorial stimuli or motor coordination training geared towards the specificities to avoid motor difficulties of freezing, when triggering factors are present. PMID:24121579

  2. Cell-encapsulating droplet formation and freezing

    NASA Astrophysics Data System (ADS)

    Ryoun Youn, Jae; Seok Song, Young

    2012-09-01

    Cell-encapsulating droplets are vitrified for biopreservation applications. The dynamics of micro-droplet formation and its freezing mechanism are analyzed numerically and experimentally. In addition, the microdroplet encapsulation technique is applied to cryopreserve cells.

  3. Adolescent depression and risk factors.

    PubMed

    Field, T; Diego, M; Sanders, C

    2001-01-01

    Seventy-nine high school seniors were administered the Center for Epidemiological Studies Depression Scale (CES-D), as well as a questionnaire on parent relationships, peer relationships, positive and negative feelings including suicidal thoughts, and lifestyle variables including academic performance, exercise, and drug use. The group of adolescents who scored above the clinical cutoff for depression on the CES-D (n = 29) had poorer relations with parents. Further, the incidence of paternal depression in that group was greater. The depressed adolescents also had less optimal peer relationships, fewer friends, and were less popular. They experienced less happiness and more frequent suicidal thoughts. They spent less time doing homework, had a lower grade point average, and spent less time exercising. The depressed group also reported more use of marijuana and cocaine. A stepwise regression indicated that physical affection with parents, homework, well-being, exercise, happiness, and parent relations explained 55% of the variance. PMID:11817630

  4. Freezing tolerance of conifer seeds and germinants.

    PubMed

    Hawkins, B J; Guest, H J; Kolotelo, D

    2003-12-01

    Survival after freezing was measured for seeds and germinants of four seedlots each of interior spruce (Picea glauca x engelmannii complex), lodgepole pine (Pinus contorta Dougl. ex Loud.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western red cedar (Thuja plicata Donn ex D. Donn). Effects of eight seed treatments on post-freezing survival of seeds and germinants were tested: dry, imbibed and stratified seed, and seed placed in a growth chamber for 2, 5, 10, 15, 20 or 30 days in a 16-h photoperiod and a 22/17 degrees C thermoperiod. Survival was related to the water content of seeds and germinants, germination rate and seedlot origin. After freezing for 3 h at -196 degrees C, dry seed of most seedlots of interior spruce, Douglas-fir and western red cedar had 84-96% germination, whereas lodgepole pine seedlots had 53-82% germination. Freezing tolerance declined significantly after imbibition in lodgepole pine, Douglas-fir and interior spruce seed (western red cedar was not tested), and mean LT50 of imbibed seed of these species was -30, -24.5 and -20 degrees C, respectively. Freezing tolerance continued to decline to a minimum LT50 of -4 to -7 degrees C after 10 days in a growth chamber for interior spruce, Douglas-fir and lodgepole pine, or after 15 days for western red cedar. Minimum freezing tolerance was reached at the stage of rapid hypocotyl elongation. In all species, a slight increase in freezing tolerance of germinants was observed once cotyledons emerged from the seed coat. The decrease in freezing tolerance during the transition from dry to germinating seed correlated with increases in seed water content. Changes in freezing tolerance between 10 and 30 days in the growth chamber were not correlated with seedling water content. Within a species, seedlots differed significantly in freezing tolerance after 2 or 5 days in the growth chamber. Because all seedlots of interior spruce and lodgepole pine germinated quickly, there was no correlation between seedlot hardiness and rate of germination. Germination rate and freezing tolerance of Douglas-fir and western red cedar seedlots was negatively correlated. There was a significant correlation between LT50 after 10 days in the growth chamber and minimum spring temperature at the location of seedlot origin for interior spruce and three seedlots of western red cedar, but no relationship was apparent for lodgepole pine and Douglas-fir. PMID:14652223

  5. Notes on the freezing of simple substances

    SciTech Connect

    Stishov, S. M.

    2006-08-15

    Experimental data on the freezing of argon and the helium isotopes at high pressures are analyzed. It is found that attractive forces in argon can be adequately described by the van der Waals mean field theory. An analogous approximation may also be applicable to helium, but this cannot be established conclusively because of quantum effects. However, an analysis of experimental results on the freezing of helium intuitively suggests that the solid-phase stability region is enlarged by quantum effects.

  6. Freezing of living cells: mechanisms and implications

    SciTech Connect

    Mazur, P.

    1984-01-01

    Cells can endure storage at low temperatures such as -196/sup 0/C for centuries. The challenge is to determine how they can survive both the cooling to such temperatures and the subsequent return to physiological conditions. A major factor is whether they freeze intracellularly. They do so if cooling is too rapid, because with rapid cooling insufficient cell water is removed osmotically to eliminate supercooling. Equations have been developed that describe the kinetics of this water loss and permit one to predict the likelihood of intracellular freezing as a function of cooling rate. Such predictions agree well with observations. Although the avoidance of intracellular freezing is usually necessary for survival, it is not sufficient. Slow freezing itself can be injurious. As ice forms outside the cell, the residual unfrozen medium forms channels of decreasing size and increasing solute concentration. The cells lie in the channels and shrink in osmotic response to the rising solute concentration. Prior theories have ascribed slow freezing injury to the concentration of solutes or the cell shrinkage. Recent experiments, however, indicate that the damage is due more to the decrease in the size of the unfrozen channels. This new view of the mechanism of slow freezing injury ought to facilitate the development of procedures for the preservation of complex assemblages of cells of biological, medical, and agricultural significance. 126 references, 18 figures, 2 tables.

  7. Real-time measurement of metabolic rate during freezing and thawing of the wood frog, Rana sylvatica: implications for overwinter energy use.

    PubMed

    Sinclair, Bremxnt J; Stinziano, Joseph R; Williams, Caroline M; Macmillan, Heath A; Marshall, Katie E; Storey, Kenneth B

    2013-01-15

    Ectotherms overwintering in temperate ecosystems must survive low temperatures while conserving energy to fuel post-winter reproduction. Freeze-tolerant wood frogs, Rana sylvatica, have an active response to the initiation of ice formation that includes mobilising glucose from glycogen and circulating it around the body to act as a cryoprotectant. We used flow-through respirometry to measure CO(2) production ( ) in real time during cooling, freezing and thawing. CO(2) production increases sharply at three points during freeze-thaw: at +1°C during cooling prior to ice formation (total of 104±17 μl CO(2) frog(-1) event(-1)), at the initiation of freezing (565±85 μl CO(2) frog(-1) freezing event(-1)) and after the frog has thawed (564±75 μ l CO(2) frog(-1) freezing event(-1)). We interpret these increases in metabolic rate to represent the energetic costs of preparation for freezing, the response to freezing and the re-establishment of homeostasis and repair of damage after thawing, respectively. We assumed that frogs metabolise lipid when unfrozen and that carbohydrate fuels metabolism during cooling, freezing and thawing, and when frozen. We then used microclimate temperature data to predict overwinter energetics of wood frogs. Based on the freezing and melting points we measured, frogs in the field were predicted to experience as many as 23 freeze-thaw cycles in the winter of our microclimate recordings. Overwinter carbohydrate consumption appears to be driven by the frequency of freeze-thaw events, and changes in overwinter climate that affect the frequency of freeze-thaw will influence carbohydrate consumption, but changes that affect mean temperatures and the frequency of winter warm spells will modify lipid consumption. PMID:23255194

  8. Relationship between heat transfer parameters and the characteristic damage variables for the freezing of beef.

    PubMed

    Mascheroni, R H; Calvelo, A

    1980-08-01

    One of the most suitable parameters for relating the freezing rate to the volume of drip produced during the thawing of meat is the characteristic time, defined as the time necessary to reduce the temperature of the sample from -1·1°C (initial freezing point in beef) to -7°C (80% of the water frozen). However, as the freezing of beef in factories takes place with important temperature gradients, distributions of these characteristic times must be expected along the pieces of frozen meat. In order to relate these characteristic time distributions to heat transfer parameters under industrial freezing conditions, a mathematical model which simulates the freezing of beef is developed in this paper. The model establishes the heat transfer equations with simultaneous change of phase, taking into account the dependence of the thermal properties with the ice content and considering the anisotropy of the thermal conductivity according to the direction of the fibres. Boundary conditions include the possibility of thermal resistances in the refrigerated interphase. The model developed was compared with laboratory experiments performed under factory freezing conditions and showed a satisfactory agreement between theory and experiment. PMID:22055769

  9. Freezing Time Estimation for a Cylindrical Food Using an Inverse Method

    NASA Astrophysics Data System (ADS)

    Hu, Yao Xing; Mihori, Tomoo; Watanabe, Hisahiko

    Most of the published methods for estimating the freezing time require thermal properties of the product and any relevant heat transfer coefficients between the product and the cooling medium. However, the difficulty of obtaining thermal data for use in industrial freezing system of food has been pointed out. We have developed a new procedure for estimating the time to freeze a food of a slab by using the inverse method, which does not require the knowledge of thermal properties of the food being frozen. The method of applying inverse method to estimation of freezing time depends on the shape of the body to be frozen. In this paper, we explored the method of applying inverse method to the food body of cylindrical shape, using selected explicit expressions to describe the temperature profile. The temperature profile was found to be successfully approximated by a logarithmic function, with which an approximate equation to describe the freezing time was derived. An inversion procedure of estimating freezing time associated with the approximate equation, was validated via a numerical experiment.

  10. Threshold temperatures mediate the impact of reduced snow cover on overwintering freeze-tolerant caterpillars

    NASA Astrophysics Data System (ADS)

    Marshall, Katie E.; Sinclair, Brent J.

    2012-01-01

    Decreases in snow cover due to climate change could alter the energetics and physiology of ectothermic animals that overwinter beneath snow, yet how snow cover interacts with physiological thresholds is unknown. We applied numerical simulation of overwintering metabolic rates coupled with field validation to determine the importance of snow cover and freezing to the overwintering lipid consumption of the freeze-tolerant Arctiid caterpillar Pyrrharctia isabella. Caterpillars that overwintered above the snow experienced mean temperatures 1.3°C lower than those below snow and consumed 18.36 mg less lipid of a total 68.97-mg reserve. Simulations showed that linear temperature effects on metabolic rate accounted for only 30% of the difference in lipid consumption. When metabolic suppression by freezing was included, 93% of the difference between animals that overwintered above and below snow was explained. Our results were robust to differences in temperature sensitivity of metabolic rate, changes in freezing point, and the magnitude of metabolic suppression by freezing. The majority of the energy savings was caused by the non-continuous reduction in metabolic rate due to freezing, the first example of the importance of temperature thresholds in the lipid use of overwintering insects.

  11. Simulations of Polar Stratospheric Clouds and Denitrification Using Laboratory Freezing Rates

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    During the 1999-2000 Arctic winter, the SAGE (Stratospheric Aerosol and Gas Experiment) III Ozone Loss and Validation Experiment (SOLVE) provided evidence of widespread solid-phase polar stratospheric clouds (PSCs) accompanied by severe nitrification. Previous simulations have shown that a freezing process occurring at temperatures above the ice frost point is necessary to explain these observations. In this work, the nitric acid freezing rates measured by Salcedo et al. and discussed by Tabazadeh et al. have been examined. These freezing rates have been tested in winter-long microphysical simulations of the 1999-2000 Arctic vortex evolution in order to determine whether they can explain the observations. A range of cases have been explored, including whether the PSC particles are composed of nitric acid dihydrate or trihydrate, whether the freezing process is a bulk process or occurs only on the particle surfaces, and uncertainties in the derived freezing rates. Finally, the possibility that meteoritic debris enhances the freezing rate has also been examined. The results of these simulations have been compared with key PSC and denitrification measurements made by the SOLVE campaign. The cases that best reproduce the measurements will he highlighted, with a discussion of the implications for our understanding of PSCs.

  12. Composition and freezing of aqueous H2SO4/HNO3 solutions under polar stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Beyer, K. D.; Seago, S. W.; Chang, H. Y.; Molina, M. J.

    1994-01-01

    The results of laboratory investigations of the freezing behavior of aqueous acid solutions indicate that in the stratosphere H2SO/H2O aerosol droplets would not freeze at temperatures above the ice frost point in the absence of HNO3; however, in the presence of typical levels of HNO3 liquid sulfuric acid aerosols take up significant amounts of HNO3 and H2O vapors and freeze much more readily. This is a consequence of the very rapid change in composition of the liquid droplets as the temperature drops to within two to three degrees of the equilibrium temperature at which HNO3 and H2O vapors would co-condense to form a liquid solution. In the high latitude stratosphere this HNO3/H2O 'dew point' is typically around 192-194 K at 100 mbar.

  13. Time perception, depression and sadness.

    PubMed

    Gil, Sandrine; Droit-Volet, Sylvie

    2009-02-01

    This study examined changes in time perception as a function of depressive symptoms, assessed for each participant with the Beck Depression Inventory (BDI). The participants performed a temporal bisection task in which they had to categorize a signal duration of between 400 and 1600 ms as either as short or long. The data showed that the bisection function was shifted toward the right, and that the point of subjective equality was higher in the depressive than in the non-depressive participants. Furthermore, the higher the depression score was, the shorter the signal duration was judged to be. In contrast, the sensitivity to time was similar in these two groups of participants. These results thus indicate that the probe durations were underestimated by the depressive participants. The sadness scores assessed by the Brief Mood Inventory Scale (BMIS) also suggest that the emotional state of sadness in the depressive participants goes some way to explaining their temporal performance. Statistical analyses and modeling of data support the idea according to which these results may be explained by a slowing down of the internal clock in the depressive participants. PMID:19073237

  14. A new freeze casting technique for ceramics

    NASA Astrophysics Data System (ADS)

    Araki, Kiyoshi

    A new freeze casting technique for ceramics capable of manufacturing near room temperature with a sublimable vehicle has been developed in order to eliminate expensive processes under extremely cold temperatures in the conventional freeze casting. Fluid concentrated slurries of Al2O 3 powder in molten camphene (C10H16) were successfully prepared at 55°C with a small amount of a dispersant. These slurries were quickly solidified (frozen) at room temperature to yield a rigid solid green body, where the frozen camphene was easily removed by sublimation (freeze-drying) with negligible shrinkage. Sintering was successfully conducted without any special binder burnout process to yield dense sintered bodies (over 98% T.D). An organic alloy with a eutectic composition in the naphthalene (C 10H8)-camphor (C10H16O) binary system with a eutectic temperature of 31°C was also found to be a successful vehicle for the new ceramic freeze casting. The fabrication processes are almost the same as those with camphene. It was found that vehicles with off-eutectic compositions resulted in large voids in the sintered body due to the ceramic particle rejection by pro-eutectic crystals during freezing. At the eutectic composition, fine lamellar microstructure in the solidified vehicle inhibits the particle rejection. The proposed advantages of the new freeze casting technique with a sublimable vehicle include; (1) elimination of extremely cold temperatures used in conventional freeze casting; (2) elimination of troublesome binder burnout process; and (3) fast manufacturing cycle due to quick solidification. Porous ceramic bodies with unique interconnected pore channels were fabricated by the new freeze casting with lower solid content. The unique channels surrounded by fully dense walls have nearly circular cross-sections unlike conventional aqueous freeze casting. The porosity and the channel diameters are controllable by the solid content in the slurry. The unique channels are replicas of entangled dendrites of frozen camphene, which sublimes during freeze-drying process. The unique porous structure with interconnected pore channels, which is completely new, is considered potentially useful in many applications such as filters and implantable bone scaffolds.

  15. Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger with Bypass Setpoint Temperature Control

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.

    2008-01-01

    Spacecraft radiators are sized for their maximum heat load in their warmest thermal environment, but must operate at reduced heat loads and in colder environments. For systems where the radiator environment can be colder than the working fluid freezing temperature, radiator freezing becomes an issue. Radiator freezing has not been a major issue for the Space Shuttle and the International Space Station (ISS) active thermal control systems (ATCSs) because they operate in environments that are warm relative to the freezing point of their external coolants (Freon-21 and ammonia, respectively). For a vehicle that lands at the Lunar South Pole, the design thermal environment is 215K, but the radiator working fluid must also be kept from freezing during the 0 K sink of transit. A radiator bypass flow control design such as those used on the Space Shuttle and ISS requires more than 30% of the design heat load to avoid radiator freezing during transit - even with a very low freezing point working fluid. By changing the traditional ATCS architecture to include a regenerating heat exchanger inboard of the radiator and by using a regenerator bypass flow control valve to maintain system setpoint, the required minimum heat load can be reduced by more than half. This gives the spacecraft much more flexibility in design and operation. The present work describes the regenerator bypass ATCS setpoint control methodology. It includes analytical results comparing the performance of this system to the traditional radiator bypass system. Finally, a summary of the advantages of the regenerator bypass system are presented.

  16. Freezing and thawing or freezing, thawing, and aging effects on beef tenderness

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this study was to determine the effect of freezing and thawing or freezing and thawing with an additional aging period after frozen storage on the tenderness of longissimus lumborum (LL) and semitendinosus (ST) steaks relative to aged, fresh steaks. Left-side LL and ST (n=35 each) ...

  17. The equilibrated state of freezing as a basis for distinguishing lethal stresses of freezing in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A model for coordination of stresses that limit winterhardiness in plants based on the thermodynamic equilibrated state of freezing and melting provides a rational basis for distinction of freeze-induced energies which can stress and injure living organisms in various ways. The departure from equili...

  18. Freeze Tolerance of Nine Zoysiagrass Cultivars Using Natural Cold Acclimation and Freeze Chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Winter hardiness of zoysiagrass (Zoysia spp.) cultivars is an important attribute throughout the biogeographical transition zone, thus the inability to withstand freezing temperatures may limit the use of these cultivars. The objective of this research was to determine the freeze tolerance (LT50) of...

  19. The role of calcium and calmodulin in freezing-induced freezing resistance of Populus tomentosa cuttings.

    PubMed

    Lin, Shan-Zhi; Zhang, Zhi-Yi; Lin, Yuan-Zhen; Zhang, Qian; Guo, Huan

    2004-02-01

    To explore the role of calcium-calmodulin messenger system in the transduction of low temperature signal in woody plants, Populus tomentosa cuttings after being treated with CaCl(2) (10 mmol/L), Ca(2+) chelator EGTA (3 mmol/L), Ca(2+) channel inhibitor LaCl(3) (100 mmol/L) or CaM antagonist CPZ (50 mmol/L) were used for freezing acclimation at -3 degrees C. The changes in the calmodulin (CaM) and malonaldehyde (MDA) contents, the activities of superoxide dismutase (SOD), peroxidase (POD) and Ca(2+)-dependent adenosinetriphosphatase (Ca(2+)-ATPase) of mitochondrial membrane as well as freezing resistance (expressed as LT(50)) of cuttings were investigated to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation increased the CaM content, the activities of SOD, POD and Ca(2+)-ATPase of mitochondrial membrane as well as freezing resistance of cuttings, and decreased the MDA content as compared with control cuttings. Treatment with CaCl(2) at the time of freezing acclimation enhanced the effect of freezing acclimation on the above-mentioned indexes, but this enhancement was abolished by Ca(2+)chelator EGTA, Ca(2+) channel inhibitor LaCl(3) or CaM antagonist CPZ, indicating that the calcium-calmodulin messenger system was involved in the course of freezing resistance development. The presence of CaCl(2) at the same time of freezing acclimation also reduced the degree of decline in CaM content, and in SOD, POD and Ca(2+)-ATPase activities caused by freezing stress at -14 degrees C, and enhanced the level of increase in CaM content, and in SOD, POD and Ca(2+)-ATPase activity in the recovery periods at 25 degrees C . The change in CaM content was found to be closely correlated to the levels of SOD, POD and Ca(2+)-ATPase, and to the degree of freezing resistance of cuttings during freezing acclimation either with or without CaCl(2) treatment. It was suggested that the increase of CaM content induced by CaCl(2) treatment promote the formation of Ca(2+)-CaM complexes, which effectively activates the activities of SOD, POD and mitochondrial Ca(2+)-ATPase and then further result in the adaptive changes associated with the development and enhancement of freezing resistance. Thus, It could be concluded that Ca(2+)-calmodulin may be involved in the regulation of the increase in SOD, POD and Ca(2+)-ATPase activities, and the induction of freezing resistance of cuttings. PMID:15583410

  20. Mapping of quantitative trait loci (QTLs) affecting autumn freezing resistance and phenology in Salix.

    PubMed

    Tsarouhas, V; Gullberg, U; Lagercrantz, U

    2004-05-01

    Quantitative trait locus (QTL) analysis was performed at different time points during cold-acclimation of a tetraploid F(2 ) Salix pedigree. The pedigree ( n=92) was derived from a cross between a frost-susceptible diploid female clone 'Jorunn' ( Salix viminalis) and a frost resistant hexaploid male clone 'SW901290' ( Salix dasyclados). Freezing resistance, height growth increment and number of new leaves were assessed at days 0, 12, 20, 24, 31 and 42 of a short day-low temperature (SD-LT) hardening regime, while the initiation of shoot tip abscission and shoot tip abscission were measured daily. Height increment, dry-to-fresh weight ratio and number of new leaves were also measured in a replicated field trial. Freezing resistance was determined from electrolyte leakage of leaf tissues and from visual injuries on stem segments, after exposure to a predetermined freeze-thaw stress. Using a genetic map of the F(2) composed of 432 single-dose AFLP markers, a total of 19 genomic regions controlling freezing resistance (10) and phenological traits (9) before and during cold-acclimation (SD-LT) were identified. The magnitude of the phenotypic variation explained by each freezing resistance locus varied over acclimation time (0-45%), and there was no time point at which all the QTLs could be detected. The single QTL detected for non-acclimated freezing resistance did not reach significance at any time point during cold-acclimation, suggesting an independent genetic relationship between non-acclimated and acclimated resistance to freezing in Salix. Five of the loci associated with freezing resistance shared common intervals with loci controlling phenological traits. Of the 14 QTLs controlling autumn freezing resistance and/or phenological traits in the indoors experiment, six (43%) were associated with autumn phenology-related traits, i.e. height increment, dry-to-fresh weight ratio and number of new leaves, measured in the field. A major locus with multi-trait association in both indoor and outdoor experiments was detected. PMID:14747916

  1. Depression in nursing home residents.

    PubMed

    Abrams, R C; Teresi, J A; Butin, D N

    1992-05-01

    Although their extent remains unclear, major and minor depressions are widespread in the nursing home population. This statement appears intuitively to be correct when consideration is given to the inactivity, decline in functional competence, loss of personal autonomy, and unavoidable confrontation with the process of death and dying that are associated with nursing home placement. In addition, some nursing home residents have had previous episodes of depression or are admitted to the facility already dysthymic or with other chronic forms of the illness. Such circumstances provide a favorable culture for the development and persistence of depressive illness. When the high frequency of other psychiatric disorders among nursing home residents is factored in, it is not surprising that long-term health care facilities have come to be regarded as de facto psychiatric hospitals. Nursing homes largely lack the treatment resources of psychiatric hospitals, however. Nursing home physicians are often unprepared to make psychiatric diagnoses, and a perfunctory annual psychiatric evaluation is insufficient to manage the complex depression syndromes of nursing home residents. Because nursing home psychiatrists typically work on a consultation basis, recommendations are not necessarily acted upon by the primary physicians. The consequences of undiagnosed and untreated depression are substantial. From the psychiatric perspective, the possibility that depression increases the risk for eventual development of permanent dementia highlights the importance of early identification for cases of reversible dementia. From the rehabilitation point of view, persistent depression among individuals with physical dependency following a catastrophic illness is associated with failure to improve in physical functioning. Depression can probably be linked to increased medical morbidity in nursing home residents, a relationship that also has been suggested for elderly medical inpatients. If so, the use of nursing time and other health-care facility services would be greater for depressed than nondepressed residents, and financial costs would be higher as well. Finally, recent data point to increased mortality in nursing home residents with major depressive disorder. It is apparent that depression in long-term care facilities is a condition with doubtful prognosis and negative medical, social, and financial consequences. The highest costs of all may be paid by nursing home residents who experience the unrelieved suffering of depressive illness. Only epidemiologic research using standard diagnostic criteria and direct resident assessment will adequately establish the magnitude of the need for intervention among depressed residents in long-term care.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1600481

  2. Freeze-drying of lactic acid bacteria.

    PubMed

    Fonseca, Fernanda; Cenard, Stéphanie; Passot, Stéphanie

    2015-01-01

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

  3. Field Response of Sugarcane Genotypes to Freeze Stress with Genotype x Environment Effects on Quality Traits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Freeze stress is a constraint to sugarcane (Saccharum sp.) with negative effect on sucrose yield, particularly during the harvest season. To understand its impact on the performance of genotypes developed by the Canal Point (CP) breeding program, the genotype by environment (GxE) interaction was app...

  4. Teen Depression

    MedlinePlus

    ... you can get back to being yourself. Regular sadness and depression are not the same Regular sadness Feeling moody, sad, or grouchy? Who doesn’t ... cry about the smallest thing. Regular moodiness and sadness usually go away quickly though, within a couple ...

  5. Towards a scientific taxonomy of depression

    PubMed Central

    K. Ranga, Rama Krishnan

    Many concepts have been introduced into the classification of depression, including manic-depressive/bipolar disorder depression, etc. Kraepelin's original concept of manic-depressive disorder has evolved into the concept of polarity, and bipolar and unipolar disorders. Psychiatric classification is characterized by an inflation of the diagnostic categories, including subtypes of depression. This rapid multiplier effect is primarily descriptive, and there is a need to rethink, in a pragmatic fashion, the classification system, in order to develop one that is likely to be of utility and which has a scientific basis. Is the time now right to ask whether there are essential conditions relevant to depression? I think that it is, and here I will introduce the notion with two such conditions. The first is early life stress disorder, and the second vascular depression. These conditions have reached a point where the data supports them as distinct entities. In this paper, the rationale for this is discussed. PMID:18979943

  6. Droplet coalescence and freezing on hydrophilic, hydrophobic, and biphilic surfaces

    NASA Astrophysics Data System (ADS)

    Van Dyke, Alexander S.; Collard, Diane; Derby, Melanie M.; Betz, Amy Rachel

    2015-10-01

    Frost and ice formation can have severe negative consequences, such as aircraft safety and reliability. At atmospheric pressure, water heterogeneously condenses and then freezes at low temperatures. To alter this freezing process, this research examines the effects of biphilic surfaces (surfaces which combine hydrophilic and hydrophobic regions) on heterogeneous water nucleation, growth, and freezing. Silicon wafers were coated with a self-assembled monolayer and patterned to create biphilic surfaces. Samples were placed on a freezing stage in an environmental chamber at atmospheric pressure, at a temperature of 295 K, and relative humidities of 30%, 60%, and 75%. Biphilic surfaces had a significant effect on droplet dynamics and freezing behavior. The addition of biphilic patterns decreased the temperature required for freezing by 6 K. Biphilic surfaces also changed the size and number of droplets on a surface at freezing and delayed the time required for a surface to freeze. The main mechanism affecting freezing characteristics was the coalescence behavior.

  7. Freeze thaw cycles in Toronto, Canada in a changing climate

    NASA Astrophysics Data System (ADS)

    Ho, E.; Gough, W. A.

    2006-01-01

    Freeze thaw cycles are examined in Toronto Canada. Using data from 1960 to 1989 for three Toronto area weather stations, trends in freeze thaw activity, the relationship to mean monthly temperature and projections of freeze thaw activity are examined. For downtown Toronto the annual frequency of freeze thaw cycles is decreasing significantly, most notably in the shoulder months of October and April. At the Pearson International Airport and the Toronto Island Airport similar annual trends were not found, however there was evidence of decreased freeze thaw activity in April and October. Polynomial curve fitting provided functional relationships between mean monthly temperature and freeze thaw activity. These relationships enabled the assessment of freeze thaw activity under synthetic warming conditions. The results of this analysis show that the warming of the magnitude typically projected for the rest of this century will not likely generate a significant change in the freeze thaw activity although there are indications that the freeze thaw season will contract.

  8. Study on Freezing of a Single Droplet

    NASA Astrophysics Data System (ADS)

    Fumoto, Koji; Yamagishi, Hideaki; Ikegawa, Masahiro

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

  9. Freezing promotes perception of coarse visual features.

    PubMed

    Lojowska, Maria; Gladwin, Thomas E; Hermans, Erno J; Roelofs, Karin

    2015-12-01

    Freezing is an evolutionarily preserved defensive behavior, characterized by immobility and heart rate deceleration, which is thought to promote visual perception. Rapid perceptual assessment of threat is crucial in life-threatening situations; for example, when policemen need to make split-second decisions about the use of deadly force. Here, we hypothesized that freezing is specifically associated with better perception of rapidly processed coarse, low-spatial frequency (LSF) features. We used a visual discrimination task in which participants determined the orientation of LSF and high-spatial frequency (HSF) gratings under threat of shock and safe conditions. As predicted, threat anticipation improved perception of LSF at the expense of HSF gratings. Crucially, stronger decrease in heart rate, a parasympathetic physiological index of freezing, was linked to better perception of LSF. These results provide empirical evidence for the comobilization of physiological and perceptual processes, which may play an important role in decision making under acute stress. PMID:26595839

  10. Directional freezing for large volume cryopreservation.

    PubMed

    Saragusty, Joseph

    2015-01-01

    Cryopreservation is currently the method of choice when it comes to long-term preservation of viable biological samples. The process, and consequently the volume of the sample, however, is limited by the ability to achieve homogenous and efficient heat removal. When this cannot be properly managed, ice crystals will grow uncontrollably resulting in extensive damage to the cryopreserved cells or tissues. Directional freezing is a technique that can be used to precisely control heat dissipation and ice crystal growth and morphology even when freezing large volumes. The technique has been used over the years to cryopreserve spermatozoa, oocytes, embryos, tissue slices and whole organs from a wide variety of domestic and wild species. In this chapter a protocol for directional freezing of spermatozoa is described and its benefits and shortcomings are discussed. PMID:25428019

  11. UltraViolet freeze-in

    NASA Astrophysics Data System (ADS)

    Elahi, Fatemeh; Kolda, Christopher; Unwin, James

    2015-03-01

    If dark matter is thermally decoupled from the visible sector, the observed relic density can potentially be obtained via freeze-in production of dark matter. Typically in such models it is assumed that the dark matter is connected to the thermal bath through feeble renormalisable interactions. Here, rather, we consider the case in which the hidden and visible sectors are coupled only via non-renormalisable operators. This is arguably a more generic realisation of the dark matter freeze-in scenario, as it does not require the introduction of diminutive renormalisable couplings. We examine general aspects of freeze-in via non-renormalisable operators in a number of toy models and present several motivated implementations in the context of Beyond the Standard Model (BSM) physics. Specifically, we study models related to the Peccei-Quinn mechanism and Z ' portals.

  12. Cell cycle regulation in the freeze tolerant wood frog, Rana sylvatica.

    PubMed

    Zhang, Jing; Storey, Kenneth B

    2012-05-01

    The wood frog (Rana sylvatica) is one of only a few vertebrate species that can survive extensive freezing of its body fluids during the winter. The mechanisms of natural freeze tolerance include metabolic rate depression to conserve energy and the implementation of cryoprotective strategies, especially the synthesis of huge amounts of glucose as a cryoprotectant. Liver is the main source of glucose production/export (and other cryoprotective actions) and plays a central role in freezing survival of the whole animal. Freezing is a multi-component stress that includes anoxia/ischemia due to the cessation of blood flow and dehydration of cells caused by ice accumulation in extracellular spaces. To help endure these stresses, cells need to suppress and reprioritize ATP-expensive cell functions. One of these is cell growth and proliferation, and we hypothesized that cell cycle arrest would be key to freezing survival. The present study examines the responses by key cell cycle components to freezing, anoxia and dehydration stresses in wood frog liver. Immunoblotting was used to investigate protein expression of Cdc 2, Cdks (2, 4, 6), and cyclins (A, B1, D1, E) as well as the phosphorylation states of Cdks (Thr14/Tyr15), the phosphatases Cdc25a (Ser76) and Cdc25c (Ser216) and the CIP/KIP Cdk inhibitors p21 (Thr145) and p27 (Thr187). Responses to 24 h freezing, 24 h anoxia and 40% dehydration as well as recovery from these stresses were analyzed. The results showed very similar responses by cell cycle components to anoxia or dehydration and were consistent with cell cycle suppression under stress and reversal during recovery. Freezing showed elements of cell cycle suppression, including reduced protein levels of Cdks and cyclins A and B1, but also showed unique responses by cyclin D1, Cdc25 phosphatases and p21/p27. These may be linked with alternative actions by these proteins that contribute to cryoprotection; e.g., an alternative action of cyclin D1 as a transcription factor may contribute to the upregulation of glucose-6-phosphatase, a key enzyme needed for the export of glucose cryoprotectant. PMID:22510573

  13. Executive functioning moderates the relationship between motivation and adolescent depressive symptoms.

    PubMed

    Vergara-Lopez, Chrystal; Lopez-Vergara, Hector I; Colder, Craig R

    2013-01-01

    We investigated the association between adolescent depressive symptoms and components of executive functioning (EF), including planning (Tower of London), set-shifting (Wisconsin Card Sorting Task), and inhibition (Stop Signal Task) in a community sample of 12-14 year olds. Further, EF was tested as a moderator of motivation (as operationalized by revised Reinforcement Sensitivity Theory) effects on depressive symptoms. Results suggested that planning ability was associated with depressive symptoms. Furthermore, planning ability moderated the relationship between motivation (fight-flight- freeze system; FFFS) and depressive symptoms, such that among adolescents with poor planning ability the FFFS positively predicted depressive symptoms, but among adolescents with strong planning ability the FFFS negatively predicts depressive symptoms. Neither set-shifting nor inhibition was associated with depressive symptoms. Findings highlight the need to consider multiple components of EF and to integrate motivational and executive dysfunction models to the study of depression. PMID:23105161

  14. Freeze drying for morphological control of inter-penetrating polymer networks

    NASA Technical Reports Server (NTRS)

    Hansen, Marion G.; Pater, Ruth H.

    1990-01-01

    The intrinsic brittleness of BMI resins can be reduced through the creation of an interpenetrating network (IPN) of BMI with a reactive-encapped thermoplastic, such as the presently considered polyimidesulfone, PISO2. The PISO2 and BMI were dissolved in a common solvent, which was then removed from the constituents by freeze drying; in an alternative method, an IPN was formed through dissolution of the constituent in a common solvent with either high or low melting point, followed by evaporative removal of the solvent. The effectiveness of the freeze-drying approach for morphological control is evaluated.

  15. Stratospheric Polar Freezing Belt Causes Denitrification

    NASA Technical Reports Server (NTRS)

    Tabazadeh, A.; Jensen, E. J.; Toon, O. B.; Drdla, K.; Schoeberl, M. R.; Gore, Warren J. (Technical Monitor)

    2001-01-01

    Trajectory cloud model calculations are presented to show that homogeneous freezing of nitric acid hydrates can produce a polar freezing belt in both hemispheres that can cause denitrification. While hydrate cloud microphysical properties are similar over both poles, the shorter persistence of clouds in the Arctic prevents the depth of the denitrified layers from growing beyond a few kilometers. The 1999-2000 Arctic winter is unique in showing a distinct denitrification profile with a depth of approx. 4.5 km that is nearly half as deep as that computed for a typical Antarctic winter.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  17. Effect of process conditions on recovery of protein activity after freezing and freeze-drying.

    PubMed

    Jiang, S; Nail, S L

    1998-05-01

    The objective of this research was to gain a better understanding of the degree to which recovery of activity of model proteins after freeze-drying can be maximized by manipulation of freeze-dry process conditions in the absence of protective solutes. Catalase, beta-galactosidase and lactate dehydrogenase (LDH) were used as model proteins. All of the three proteins exhibited a concentration-dependent loss of activity after freezing, with significantly higher recovery at higher concentration. The freezing method and the type of buffer were also important, with sodium phosphate buffer and freezing by immersion of vials in liquid nitrogen associated with the lowest recovery of activity. Differential scanning calorimetry was predictive of the onset of collapse during freeze-drying only for beta-galactosidase. For the other proteins, either no Tg' transition was observed, or the apparent glass transition did not correlate with the microscopically-observed collapse temperature. The time course of activity loss for beta-galactosidase and LDH was compared during freeze-drying under conditions which produced collapse of the dried matrix and conditions which produced retention of microstructure in the dried solid. Recovery of activity decreased continuously during primary drying, with no sharp drop in recovery of activity associated with the onset of collapse. The most important drying process variable affecting recovery of activity was residual moisture level, with a dramatic drop in activity recovery associated with residual moisture levels less than about 10%. PMID:9653629

  18. To freeze or not to freeze embryos: clarity, confusion and conflict.

    PubMed

    Goswami, Mohar; Murdoch, Alison P; Haimes, Erica

    2015-06-01

    Although embryo freezing is a routine clinical practice, there is little contemporary evidence on how couples make the decision to freeze their surplus embryos, or of their perceptions during that time. This article describes a qualitative study of 16 couples who have had in vitro fertilisation (IVF) treatment. The study question was 'What are the personal and social factors that patients consider when deciding whether to freeze embryos?' We show that while the desire for a baby is the dominant drive, couples' views revealed more nuanced and complex considerations in the decision-making process. It was clear that the desire to have a baby influenced couples' decision-making and that they saw freezing as 'part of the process'. However, there were confusions associated with the term 'freezing' related to concerns about the safety of the procedure. Despite being given written information, couples were confused about the practical aspects of embryo freezing, which suggests they were preoccupied with the immediate demands of IVF. Couples expressed ethical conflicts about freezing 'babies'. We hope the findings from this study will inform clinicians and assist them in providing support to couples confronted with this difficult decision-making. PMID:25660099

  19. Determination of ethanol in whey-sugar solutions by freezing. [Kluyveromyces fragilis and Saccharomyces cerevisiae

    SciTech Connect

    Demott, B.J.

    1982-01-01

    The composition of solutions undergoing yeast fermentation was stimulated by using direct-acid-set cottage cheese whey containing increasing amounts of EtOH (0 to 5.4%) with decreasing amounts of sucrose (10 to 0%). Each decrease of 0.54 g EtOH decreased specific gravity by 0.0046 unit and lowered the freezing point by 0.159 H (the Hortvet unit). Whey containing 10% added sucrose was treated as follows: (a) inoculated with Kluyveromyces fragilis, (b) carbohydrate splitting enzymes added and inoculated with Kluyveromyces fragilis and (c) carbohydrate splitting enzymes added and inoculated with Saccharomyces cerevisiae. All mixtures were incubated 48 h at 32 degrees during which 6 samples from each treatment were analyzed for total solids, specific gravity and freezing point. No difference was noted between samples treated with enzymes or those treated with the 2 yeasts cultured as related to decrease in total solids concentration or specific gravity. Each 0.001 H decrease in freezing point was accompanied by a total solids decrease of 0.006 g/100 g whey in the nonenzyme treated sample, and 0.008 g and 0.010 g/100 g whey in the enzyme-treated samples inoculated with Kluyveromyces fragilis and Saccharomyces cerevisiae, respectively. Each 0.001 H change in freezing point was equivalent to a change of 0.00003 specific gravity unit in the nonenzyme-treated sample and 0.000043 and 0.000048 specific gravity unit in the enzyme-treated samples inoculated with Kluyveromyces fragilis and Saccharomyces cerevisiae, respectively. The precision with which freezing point can be determined suggests its use in evaluating the amount of EtOH produced during fermentation.

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

    PubMed

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

    2013-07-15

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

  1. Freezing cleans food processing wastewater

    SciTech Connect

    1998-12-31

    Snowfluent is a technology which atomizes wastewater effluent and sprays it into the air as ice crystals at cold temperatures. It has been found effective in treating municipal sewage and food processing wastes. This bulletin reviews pilot- and production-scale studies conducted at an Alberta malt producer to test whether the Snowfluent process has further applications for the treatment of food processing wastes. The study was designed to determine the percentage of nutrients removed by the technology, the point at which contaminants are reduced, the effect of the process on the shallow water table, and the health risk to operators involved.

  2. Freezing cleans food processing wastewater

    SciTech Connect

    Not Available

    1998-01-01

    Snowfluent is a technology which atomizes wastewater effluent and sprays it into the air as ice crystals at cold temperatures. It has been found effective in treating municipal sewage and food processing wastes. This bulletin reviews pilot- and production-scale studies conducted at an Alberta malt producer to test whether the Snowfluent process has further applications for the treatment of food processing wastes. The study was designed to determine the percentage of nutrients removed by the technology, the point at which contaminants are reduced, the effect of the process on the shallow water table, and the health risk to operators involved.

  3. Dimensional analysis, spin freezing and magnetization in spin ice

    NASA Astrophysics Data System (ADS)

    Bramwell, Steven T.

    2011-03-01

    Dimensional analysis is shown to give an insight into the non-ergodic behaviour of spin ice below its apparent 'spin freezing' temperature. Expressions are derived for the temperature-dependent magnetic susceptibility that are found to be highly consistent with the previously reported field cooled and zero field cooled magnetization of the spin ice dysprosium titanate, Dy2Ti2O7, as well as with the theory of a 'magnetolyte', including Debye-Hückel screening and Wien dissociation. The spin freezing is inferred to reflect the inability of the quasi-free magnetic charges or 'monopoles' that comprise the magnetolyte to fully screen an applied magnetic field on the timescale of an experiment. The apparent freezing temperature (Tf≈0.65 K) is identified as the point where the Debye screening length becomes greater than the Bjerrum association distance for charge pairs. Combining these dimensional arguments with Onsager's theory of the Wien effect, it is shown that magnetization data at relatively high field (Snyder et al 2004 Phys. Rev. B 69 064414) may be used to estimate the elementary magnetic charge of spin ice, as well as the temperature-dependent monopole density. Evidence is presented of a non-equilibrium population of monopoles below T≈0.2 K. It is also shown how Onsager's microscopic theory of field-induced monopole pair separation naturally suggests the 'magnetization jumps' in Dy2Ti2O7 observed at applied fields of the order of ~ 0.1 T. It is concluded that the results of dimensional analysis, when combined with Onsager's theory, provide an accurate, albeit approximate, description of the properties of Dy2Ti2O7, that could be improved by the development of a lattice theory of the Wien effect, or tested on other spin ice materials.

  4. Freezing resistance varies within the growing season and with elevation in high-Andean species of central Chile.

    PubMed

    Sierra-Almeida, Angela; Cavieres, Lohengrin A; Bravo, León A

    2009-01-01

    Predicted increases in the length of the growing season as a result of climate change may more frequently expose high-elevation plants to severe frosts. Understanding the ability of these species to resist frosts during the growing season is essential for predicting how species may respond to changes in temperature regimes. Here, we assessed the freezing resistance of 24 species from the central Chilean Andes by determining their low temperature damage (LT(50)), ice nucleation temperature (NT), freezing point (FP) and freezing resistance mechanism (i.e. avoidance or tolerance). The Andean species were found to resist frosts from -8.2 to -19.5 degrees C during the growing season, and freezing tolerance was the most common resistance mechanism. Freezing resistance (LT(50)) varied within the growing season, decreasing towards the end of this period in most of the studied species. However, the FP showed the opposite trend. LT(50) increased with elevation, whilst FP was lower in plants from lower elevations, especially late in the growing season. Andean species have the potential to withstand severe freezing conditions during the growing season, and the aridity of this high-elevation environment seems to play an important role in determining this high freezing resistance. PMID:19210722

  5. Structural precursor to freezing in the hard-disk and hard-sphere systems

    NASA Astrophysics Data System (ADS)

    Truskett, Thomas M.; Torquato, Salvatore; Sastry, Srikanth; Debenedetti, Pablo G.; Stillinger, Frank H.

    1998-09-01

    We show that the simplest model fluids in two and three dimensions, namely, the hard-disk and hard-sphere fluids, exhibit a structural precursor to the freezing transition, which manifests itself as a shoulder in the second peak of the radial distribution function. This feature is not present in the radial distribution function of the low-density fluid. Close examination of the two-dimensional fluid configurations in the vicinity of the freezing transition reveals that the shoulder corresponds to the formation of a distinct structural motif, identifiable as a four-particle hexagonally close-packed arrangement. As the dense fluid approaches the freezing transition, the ordered arrangements form large embryonic domains, commensurate with those seen in the crystal at the melting point. Contrary to the notion that the split second peak is a signature of the amorphous solid, our results support the idea that it is a precursor to the development of long-range order.

  6. Effect of chlorine, blanching, freezing, and microwave heating on Cryptosporidium parvum viability inoculated on green peppers.

    PubMed

    Duhain, G L M C; Minnaar, A; Buys, E M

    2012-05-01

    Cryptosporidium parvum oocysts have been found on the surface of vegetables in both developed and developing countries. C. parvum can contaminate vegetables via various routes, including irrigation water. This study investigated the effect of individual treatments of chlorine, blanching, blast freezing, and microwave heating, as well as combined treatments of chlorine and freezing, and chlorine and microwave heating on the viability of C. parvum oocysts inoculated on green peppers. The viability of the oocysts after the treatments was assessed using propidium iodide and a flow cytometer. Based on the propidium iodide staining, the chlorine treatments did not affect the viability of the oocysts. Blast freezing significantly inactivated 20% of the oocysts. Microwave heating and blanching significantly inactivated 93% of oocysts. Treatment with chlorine followed by blast freezing did not affect the viability of the oocysts significantly. Treatment with chlorine and microwave heating was significantly more effective than microwave heating alone and inactivated 98% of the oocysts. The study indicates that C. parvum oocysts are sensitive to heat and, to some extent, to blast freezing, but are resistant to chlorine. Therefore, the use of chlorine during vegetable processing is not a critical control point for C. parvum oocysts, and the consumption of raw or minimally processed vegetables may constitute a health risk as C. parvum oocysts can still be found viable on ready-to-eat, minimally processed vegetables. PMID:22564944

  7. Infrared Thermography for Monitoring of Freeze-Drying Processes: Instrumental Developments and Preliminary Results

    PubMed Central

    Emteborg, Håkan; Zeleny, Reinhard; Charoud-Got, Jean; Martos, Gustavo; Lüddeke, Jörg; Schellin, Holger; Teipel, Katharina

    2014-01-01

    Coupling an infrared (IR) camera to a freeze dryer for on-line monitoring of freeze-drying cycles is described for the first time. Normally, product temperature is measured using a few invasive Pt-100 probes, resulting in poor spatial resolution. To overcome this, an IR camera was placed on a process-scale freeze dryer. Imaging took place every 120 s through a Germanium window comprising 30,000 measurement points obtained contact-free from −40°C to 25°C. Results are presented for an empty system, bulk drying of cheese slurry, and drying of 1 mL human serum in 150 vials. During freezing of the empty system, differences of more than 5°C were measured on the shelf. Adding a tray to the empty system, a difference of more than 8°C was observed. These temperature differences probably cause different ice structures affecting the drying speed during sublimation. A temperature difference of maximum 13°C was observed in bulk mode during sublimation. When drying in vials, differences of more than 10°C were observed. Gradually, the large temperature differences disappeared during secondary drying and products were transformed into uniformly dry cakes. The experimental data show that the IR camera is a highly versatile on-line monitoring tool for different kinds of freeze-drying processes. © 2014 European Union 103:2088–2097, 2014 PMID:24902839

  8. Infrared thermography for monitoring of freeze-drying processes: instrumental developments and preliminary results.

    PubMed

    Emteborg, Håkan; Zeleny, Reinhard; Charoud-Got, Jean; Martos, Gustavo; Lüddeke, Jörg; Schellin, Holger; Teipel, Katharina

    2014-07-01

    Coupling an infrared (IR) camera to a freeze dryer for on-line monitoring of freeze-drying cycles is described for the first time. Normally, product temperature is measured using a few invasive Pt-100 probes, resulting in poor spatial resolution. To overcome this, an IR camera was placed on a process-scale freeze dryer. Imaging took place every 120 s through a Germanium window comprising 30,000 measurement points obtained contact-free from -40 °C to 25 °C. Results are presented for an empty system, bulk drying of cheese slurry, and drying of 1 mL human serum in 150 vials. During freezing of the empty system, differences of more than 5 °C were measured on the shelf. Adding a tray to the empty system, a difference of more than 8 °C was observed. These temperature differences probably cause different ice structures affecting the drying speed during sublimation. A temperature difference of maximum 13 °C was observed in bulk mode during sublimation. When drying in vials, differences of more than 10 °C were observed. Gradually, the large temperature differences disappeared during secondary drying and products were transformed into uniformly dry cakes. The experimental data show that the IR camera is a highly versatile on-line monitoring tool for different kinds of freeze-drying processes. PMID:24902839

  9. FREEZE-FRAME: Fast Action Stress Relief.

    ERIC Educational Resources Information Center

    Childre, Doc Lew

    Recent scientific research has proven that we can, not only manage our stress, we can even prevent it. Ways to achieve stress management are presented in this book. It details a method called FREEZE-FRAME, a process in which individuals mentally stop the chaos that surrounds them and then calmly contemplate their situation. The text opens with an

  10. Unitarity Constraints on Asymmetric Freeze-In

    SciTech Connect

    Hook, Anson; /SLAC

    2011-08-15

    This paper considers unitarity and CPT constraints on asymmetric freeze-in, the use of freeze-in to store baryon number in a dark sector. In this scenario, Sakharov's out of equilibrium condition is satisfied by placing the visible and hidden sectors at different temperatures while a net visible baryon number is produced by storing negative baryon number in a dark sector. It is shown that unitarity and CPT lead to unexpected cancellations. In particular, the transfer of baryon number cancels completely at leading order. This note has shown that if two sectors are in thermal equilibrium with themselves, but not with each other, then the leading effect transferring conserved quantities between the two sectors is of order the the weak coupling connecting them to the third power. When freeze-in is used to produce a net baryon number density, the leading order effect comes from {Omicron}({lambda}{sup 3}) diagrams where the intermediate state that goes on-shell has a different visible baryon number than the final state visible baryon number. Models in which the correct baryon number is generated with freeze-in as the dominant source of abundance, typically require {lambda} {approx}> 10{sup -6} and m{sub bath} {approx}> TeV. m{sub bath} is the mass of the visible particle which communicates with the hidden sector. The lower window is potentially observable at the LHC.

  11. Polybutylene pipe freeze/thaw reliability testing

    SciTech Connect

    Farrington, R.B.

    1987-04-01

    This paper discusses the ability of polybutylene pipe to withstand repeated freezing and thawing. The test apparatus, test procedure, list of chronological events, and results are discussed. Polybutylene piping has potential use in active solar heating systems and integral-collector-storage systems.

  12. Aversive life events enhance human freezing responses.

    PubMed

    Hagenaars, Muriel A; Stins, John F; Roelofs, Karin

    2012-02-01

    In the present study, we investigated the effect of prior aversive life events on freezing-like responses. Fifty healthy females were presented neutral, pleasant, and unpleasant images from the International Affective Picture System while standing on a stabilometric platform and wearing a polar band to assess body sway and heart rate. In the total sample, only unpleasant pictures elicited reduced body sway and reduced heart rate (freezing). Moreover, participants who had experienced 1 or more aversive life events showed greater reductions in heart rate for unpleasant versus pleasant pictures than those who had experienced no such event. In addition, relative to no-event participants, single-event participants showed reduced body sway to unpleasant pictures, while multiple-event participants showed reduced body sway in response to all picture categories. These results indicate that aversive life events affect automatic freezing responses and may indicate the cumulative effect of multiple trauma. The experimental paradigm presented is a promising method to study freezing as a primary defense response in trauma-related disorders. PMID:21767043

  13. Managing damaging freeze events in Louisiana sugarcane

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exposure of sugarcane to damaging frosts occurs in approximately 25% of the sugarcane producing countries of the world, but is most frequent on the mainland of the United States, especially in the state of Louisiana. The frequent winter freezes that occur in the sugarcane areas of Louisiana have fo...

  14. FREEZE-FRAME: Fast Action Stress Relief.

    ERIC Educational Resources Information Center

    Childre, Doc Lew

    Recent scientific research has proven that we can, not only manage our stress, we can even prevent it. Ways to achieve stress management are presented in this book. It details a method called FREEZE-FRAME, a process in which individuals mentally stop the chaos that surrounds them and then calmly contemplate their situation. The text opens with an…

  15. Freeze-thaw induced gelation of alginates.

    PubMed

    Zhao, Ying; Shen, Wei; Chen, Zhigang; Wu, Tao

    2016-09-01

    Adding divalent ions or lowering pH below the pKa values of alginate monomers are common ways in preparing alginate gels. Herein a new way of preparing alginate gels using freeze-thaw technique is described. Solvent crystallization during freezing drove the polymers to associate into certain structures that became the junction zones of hydrogels after thawing. It enabled the preparation of alginate gels at pH 4.0 and 3.5, two pH at which the gel could not be formed previously. At pH 3.0 where alginate gel could be formed initially, applying freeze-thaw treatment increased the gel storage modulus almost 100 times. The formation of hydrogels and the resulting gel properties, such as dynamic moduli and gel syneresis were influenced by the pH values, number of freeze-thaw cycles, alginate concentrations, and ionic strengths. The obtained hydrogels were soft and demonstrated a melting behavior upon storage, which may find novel applications in the biomedical industry. PMID:27185114

  16. Directional freezing of sperm and associated derived technologies.

    PubMed

    Arav, Amir; Saragusty, Joseph

    2016-06-01

    Directional freezing has now completed 30 years of development since it was first introduced to cryobiology. In the field of sperm cryopreservation, directional freezing has been shown to be advantageous over slow freezing for numerous domestic and wildlife species. In particular, it was shown that freezing of large volume is possible. Furthermore, double freezing of sperm and freezing of sex-sorted sperm are possible and became the routine in the sex sorted sperm industry. In wild animals, our labs and others showed that sperm from a wide range of terrestrial and aquatic species can be successfully cryopreserved using directional freezing. Finally, we will describe for the first time the successful freeze-drying of human sperm in an aseptic method. Using a device that produces clean liquid air, we froze human sperm in small droplets and then dried them in a bench top lyophilizer that was sterilized prior to use. More than 80% of DNA integrity was found after rehydration. PMID:26879097

  17. Nucleation Pathways For Freezing Of Two Grades Of Zirconium

    NASA Technical Reports Server (NTRS)

    Rhim, Won-Kyu; Rulison, Aaron; Bayuzick, Robert; Hofmeister, William; Morton, Craig

    1996-01-01

    Report discusses classical nucleation theory of freezing and describes experimental study of nucleation mechanisms that predominate during freezing of spherical specimens of initially molten zirconium levitated electrostatically in vacuum.

  18. Canalization of freeze tolerance in an alpine grasshopper.

    PubMed

    Hawes, Timothy C

    2015-10-01

    In the Rock and Pillar Range, New Zealand, the alpine grasshopper, Sigaus australis Hutton, survives equilibrium freezing (EF) all-year round. A comparison of freeze tolerance (FT) in grasshoppers over four austral seasons for a 1 year period finds that: (a) the majority (>70%) of the sample population of grasshoppers survive single freeze-stress throughout the year; (b) exposure to increased freeze stress (multiple freeze-stress events) does not lead to a loss of freeze tolerance; and (c) responses to increased freeze stress reveal seasonal tuning of the FT adaptation to environmental temperatures. The Rock and Pillar sample population provides a clear example of the canalization of the FT adaptation. Seasonal variability in the extent of tolerance of multiple freezing events indicates that physiology is modulated to environmental temperatures by phenotypic plasticity - i.e. the FT adaptation is permanent and adjustable. PMID:26210007

  19. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, WIDTH AND WEIGHT LIMITATIONS § 658.23 LCV freeze... and pavement design characteristics of the alternate route should be equivalent to those of...

  20. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, WIDTH AND WEIGHT LIMITATIONS § 658.23 LCV freeze... and pavement design characteristics of the alternate route should be equivalent to those of...

  1. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... OPERATIONS TRUCK SIZE AND WEIGHT, ROUTE DESIGNATIONS-LENGTH, WIDTH AND WEIGHT LIMITATIONS § 658.23 LCV freeze... and pavement design characteristics of the alternate route should be equivalent to those of...

  2. The influence of freezing and freeze-drying of tissue specimens on enzyme activity.

    PubMed

    Meijer, A E; Benson, D; Scholte, H R

    1977-04-01

    In the presented study the influence of freezing and freeze-drying on enzyme activity is described. Attention is paid to 16 enzymes which can be used for quantitative enzyme histochemical techniques. With the exception of succinate dehydrogenase only, no significant inactivation during freezing and freeze-drying procedures could be demonstrated with lactate dehydrogenase, malate dehydrogenase (NAD+), malate dehydrogenase (decarboxylating) (NADP+), isocitrate dehydrogenase (NADP+), glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, NADH-oxydoreductase, mitochondrial glycerol-3-phosphate dehydrogenase, cytochrome c oxidase, phosphoglucomutase, glucosephosphate isomerase, glucose-6-phosphatase, acid phosphatase, beta-glucuronidase and non specific aryl esterase. Therefore, the results supply a sound foundation for those quantitative enzyme histochemical techniques in which tissue specimens are frozen or frozen-dried before enzyme estimations are performed. PMID:870461

  3. High-presssure shift freezing. Part 2. Modeling of freezing times for a finite cylindrical model.

    PubMed

    Sanz, P D; Otero, L

    2000-01-01

    A comprehensive vision of the heat transfer process involved in high-pressure shift freezing (HPSF) is shown in comparison to the process at atmospheric pressure. In addition, a mathematical model to predict the freezing times is presented. This model takes into consideration the dependence of the thermophysical properties relating to temperature and pressure and the supercooling reached by liquid water at atmospheric pressure after adiabatic expansion in the HPSF process. Experimental and theoretical data appear to agree. PMID:11101332

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

    PubMed

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

    2004-06-01

    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

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

    SciTech Connect

    Larsen, N.; Knudsen, B.; Rosen, J.M.

    1995-05-15

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

  6. Objective video quality assessment method for freeze distortion based on freeze aggregation

    NASA Astrophysics Data System (ADS)

    Watanabe, Keishiro; Okamoto, Jun; Kurita, Takaaki

    2006-01-01

    With the development of the broadband network, video communications such as videophone, video distribution, and IPTV services are beginning to become common. In order to provide these services appropriately, we must manage them based on subjective video quality, in addition to designing a network system based on it. Currently, subjective quality assessment is the main method used to quantify video quality. However, it is time-consuming and expensive. Therefore, we need an objective quality assessment technology that can estimate video quality from video characteristics effectively. Video degradation can be categorized into two types: spatial and temporal. Objective quality assessment methods for spatial degradation have been studied extensively, but methods for temporal degradation have hardly been examined even though it occurs frequently due to network degradation and has a large impact on subjective quality. In this paper, we propose an objective quality assessment method for temporal degradation. Our approach is to aggregate multiple freeze distortions into an equivalent freeze distortion and then derive the objective video quality from the equivalent freeze distortion. Specifically, our method considers the total length of all freeze distortions in a video sequence as the length of the equivalent single freeze distortion. In addition, we propose a method using the perceptual characteristics of short freeze distortions. We verified that our method can estimate the objective video quality well within the deviation of subjective video quality.

  7. Shyness Predicts Depressive Symptoms among Adolescents : A Prospective Study

    ERIC Educational Resources Information Center

    Murberg, Terje A.

    2009-01-01

    This study examines the relation between shyness, social support and depressive symptoms in a sample of 259 students (aged 14-16 years) in two secondary schools. Results at both time-points showed positive associations of depressive symptoms with shyness and with being female and negative associations of depressive symptoms with social support and…

  8. VISUALIZATION OF FREEZING PROGRESSION IN TURFGRASSES USING INFRARED VIDEO THERMOGRAPHY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Freezing injury can be a significant problem in turfgrasses. Understanding how freezing develops and ramifies throughout the plant could assist in the development of improved management or screening processes for cultivar improvemen. The development of freezing injury is not well understand due pa...

  9. 7 CFR 58.620 - Freezing and packaging rooms.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Freezing and packaging rooms. 58.620 Section 58.620 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall...

  10. 7 CFR 58.620 - Freezing and packaging rooms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Freezing and packaging rooms. 58.620 Section 58.620 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall...

  11. 7 CFR 58.638 - Freezing the mix.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture... Procedures § 58.638 Freezing the mix. After the mix enters the freezer, it shall be frozen as rapidly as... and further freezing....

  12. 7 CFR 58.638 - Freezing the mix.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture... Procedures § 58.638 Freezing the mix. After the mix enters the freezer, it shall be frozen as rapidly as... and further freezing....

  13. 7 CFR 58.638 - Freezing the mix.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture... Procedures § 58.638 Freezing the mix. After the mix enters the freezer, it shall be frozen as rapidly as... and further freezing....

  14. Genetics of winter wheat response to two freezing treatments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The inheritance of the ability of winter wheat plants to survive two kinds of freezing stress was investigated in a five-parent diallel cross. Plants were acclimated at +4°C for 5 wks and frozen with or without a –3°C, 16-hour pre-freezing (PF) period prior to freezing to damaging temperatures. The ...

  15. 7 CFR 58.620 - Freezing and packaging rooms.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Freezing and packaging rooms. 58.620 Section 58.620 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall...

  16. 7 CFR 58.620 - Freezing and packaging rooms.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Freezing and packaging rooms. 58.620 Section 58.620 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall...

  17. 7 CFR 58.620 - Freezing and packaging rooms.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Freezing and packaging rooms. 58.620 Section 58.620 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall...

  18. Modification of physical properties of freeze-dried rice

    NASA Technical Reports Server (NTRS)

    Huber, C. S.

    1971-01-01

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

  19. Interspecific analysis of xylem freezing responses in Acer and Betula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Temperate woody plants have evolved two methods for coping with seasonal exposure to sub-zero temperatures. Supercooling is a freeze-avoidance strategy where cells are able to resist the freezing of intracellular water below sub-zero temperatures. Non-supercooling is a freeze-tolerance strategy wh...

  20. Depression: What We Know.

    ERIC Educational Resources Information Center

    Lobel, Brana; Hirschfeld, Robert M. A.

    This booklet is concerned with the area of clinical depression. Questions about clinical depression are briefly answered in an overview section and are examined in greater detail in the five chapters that follow. In chapter 1, depression is defined and various types of depression are identified. The origins of depression are explored in the second…

  1. Strategy of freeze tolerance in adult of sunn pest bug (Eurygaster integriceps Put.).

    PubMed

    Baghdadi, Ahmed

    2007-01-01

    To investigate cold hardiness of Eurygaster integriceps Put, super cooling points of whole bodies during December to March 2006-2007 were measured on samples collected from altitude of Ghara-aghaj varamin-Iran. In addition, the lower lethal temperature (LLT) was determined for adult insect. The super cooling points were observed about -5 in cold months. Since the minimum temperature under natural condition is reached to-7 degreesC or lower in January and LLT99 (-21.65 degrees C), --11 degreesC lower than their minimum SCP (-10.5 degrees C), therefore I concluded that adult insects are freeze tolerant. Furthermore, super cooling points of different sex, weight and attitude were not significantly different. Freeze tolerance in these insects may be a strategy to provide protection from long-term exposures to ice crystals in microhabitat in alititude. PMID:18399476

  2. Depression after Stroke

    MedlinePlus

    ... Library CARING FOR SOMEONE WITH EMOTIONAL & BEHAVIORAL NEEDS Depression After Stroke After a stroke, your loved one ... available! Almost half of all stroke survivors have depression. Depression is a normal response to the losses ...

  3. Persistent depressive disorder

    MedlinePlus

    PDD; Chronic depression; Depression - chronic ... The exact cause of persistent depressive disorder (PDD) is unknown. It tends to run in families. PDD occurs more often in women. Most people with PDD will also ...

  4. Understanding Depression (For Parents)

    MedlinePlus

    ... disorder with depressed mood, seasonal affective disorder , and bipolar disorder (or manic depression). All of these can ... dysthymic disorder go on to develop major depression.) Bipolar disorder , another type of mood disturbance, is marked ...

  5. Primary care management of depression in children and adolescents.

    PubMed

    Haefner, Judy

    2016-06-19

    Depression is the most common mental health disorder in children and adolescents, and primary care is often the first point of contact for children and adolescents with depression. Depression impacts all areas of life, impairing academics and interactions with family and friends. The purpose of this article is to help NPs identify and treat children and adolescents presenting with depression in the primary care setting. PMID:27214067

  6. Hibernation physiology, freezing adaptation and extreme freeze tolerance in a northern population of the wood frog.

    PubMed

    Costanzo, Jon P; do Amaral, M Clara F; Rosendale, Andrew J; Lee, Richard E

    2013-09-15

    We investigated hibernation physiology and freeze tolerance in a population of the wood frog, Rana sylvatica, indigenous to Interior Alaska, USA, near the northernmost limit of the species' range. Winter acclimatization responses included a 233% increase in the hepatic glycogen depot that was subsidized by fat body and skeletal muscle catabolism, and a rise in plasma osmolality that reflected accrual of urea (to 106±10 μmol ml(-1)) and an unidentified solute (to ~73 μmol ml(-1)). In contrast, frogs from a cool-temperate population (southern Ohio, USA) amassed much less glycogen, had a lower uremia (28±5 μmol ml(-1)) and apparently lacked the unidentified solute. Alaskan frogs survived freezing at temperatures as low as -16°C, some 10-13°C below those tolerated by southern conspecifics, and endured a 2-month bout of freezing at -4°C. The profound freeze tolerance is presumably due to their high levels of organic osmolytes and bound water, which limits ice formation. Adaptive responses to freezing (-2.5°C for 48 h) and subsequent thawing (4°C) included synthesis of the cryoprotectants urea and glucose, and dehydration of certain tissues. Alaskan frogs differed from Ohioan frogs in retaining a substantial reserve capacity for glucose synthesis, accumulating high levels of cryoprotectants in brain tissue, and remaining hyperglycemic long after thawing. The northern phenotype also incurred less stress during freezing/thawing, as indicated by limited cryohemolysis and lactate accumulation. Post-glacial colonization of high latitudes by R. sylvatica required a substantial increase in freeze tolerance that was at least partly achieved by enhancing their cryoprotectant system. PMID:23966588

  7. Spacecraft Radiator Freeze Protection Using a Regenerative Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Schunk, Richard G.

    2011-01-01

    An active thermal control system architecture has been modified to include a regenerative heat exchanger (regenerator) inboard of the radiator. Rather than using a radiator bypass valve a regenerative heat exchanger is placed inboard of the radiators. A regenerator cold side bypass valve is used to set the return temperature. During operation, the regenerator bypass flow is varied, mixing cold radiator return fluid and warm regenerator outlet fluid to maintain the system setpoint. At the lowest heat load for stable operation, the bypass flow is closed off, sending all of the flow through the regenerator. This lowers the radiator inlet temperature well below the system set-point while maintaining full flow through the radiators. By using a regenerator bypass flow control to maintain system setpoint, the required minimum heat load to avoid radiator freezing can be reduced by more than half compared to a radiator bypass system.

  8. Biotechnological applications of plant freezing associated proteins.

    PubMed

    Breton, G; Danyluk, J; Ouellet, F; Sarhan, F

    2000-01-01

    Plants use a wide array of proteins to protect themselves against low temperature and freezing conditions. The identification of these freezing tolerance associated proteins and the elucidation of their cryoprotective functions will have important applications in several fields. Genes encoding structural proteins, osmolyte producing enzymes, oxidative stress scavenging enzymes, lipid desaturases and gene regulators have been used to produce transgenic plants. These studies have revealed the potential capacity of different genes to protect against temperature related stresses. In some cases, transgenic plants with significant cold tolerance have been produced. Furthermore, the biochemical characterization of the cold induced antifreeze proteins and dehydrins reveals many applications in the food and the medical industries. These proteins are being considered as food additives to improve the quality and shelf-life of frozen foods, as cryoprotective agents for organ and cell cryopreservation, and as chemical adjuvant in cancer cryosurgery. PMID:11193297

  9. Freeze-out, Hadronization and Statistical Model

    NASA Astrophysics Data System (ADS)

    Castorina, Paolo

    2016-01-01

    The comparison of the statistical hadronization model with experimental data and lattice QCD results is not always straightforward. Indeed, the interpretation of the ϕ meson production, of the proton to pion multiplicity ratio at LHC and the agreement of the freeze-out curve with the lattice critical line in the T — µB plane, require further analyses. Moreover the dynamics of the hadronization has to be compatible with: 1) the statitical behavior also observed in elementary high energy collisions; 2) a universal hadronization temperature for all high energy collisions; 3) the freeze-out criteria. In these lecture notes the SHM is recalled and some explanations of the puzzling aspects of its comparison with data are discussed.

  10. [Non-freezing cold injury in soldiers].

    PubMed

    Melamed, E; Glassberg, E

    2002-12-01

    Non-freezing cold injury (NFCI) is an injury of the hands or feet resulting from exposure to wet conditions and temperatures just above freezing, typically found in soldiers. NFCI is due to microvascular endothelial damage, stasis and vascular occlusion. At first, the tissue is cold and anesthetic, progressing to hyperemia in 24-48 hours. Hyperemia is accompanied by an intense painful burning sensation as well as blisters, redness, and possibly, ulcerations. NFCI management raises frustration in both medical officers and commanders. Most authorities are not aware of or remain unimpressed with the severity of NFCI, nor do they realize that it produces lifelong symptomatology. The following review of the available literature attempts to clear up some issues regarding the definition, pathogenesis, symptoms and preventative measures available in NFCI, including our own experience. PMID:12534203

  11. Ground freezing for containment of hazardous waste

    SciTech Connect

    Sayles, F.N.; Iskandar, I.K.

    1998-07-01

    The freezing of ground for the containment of subsurface hazardous waste is a promising method that is environmentally friendly and offers a safe alternative to other methods of waste retention in many cases. The frozen soil method offers two concepts for retaining waste. One concept is to freeze the entire waste area into a solid block of frozen soil thus locking the waste in situ. For small areas where the contaminated soil does not include vessels that would rupture from frost action, this concept may be simpler to install. A second concept, of course, is to create a frozen soil barrier to confine the waste within prescribed unfrozen soil boundaries; initial research in this area was funded by EPA, Cincinnati, OH, and the Army Corps of Engineers. The paper discusses advantages and limitations, a case study from Oak Ridge, TN, and a mesh generation program that simulates the cryogenic technology.

  12. Fast Melting and Freezing for Microgravity Experiments

    NASA Technical Reports Server (NTRS)

    Poorman, Richard M.

    1987-01-01

    Commercial tube welders adapted to metallurgical research. Proposed furnace melts and resolidifies small metal samples during brief periods. In furnace, sample surrounded by large heat sinks and rapidly heated near midlength by intense source of heat. Furnace intended for use in experiments in microgravity: entire melting-and-freezing process requires less than 20 s of near weightlessness experienced in parabolic climb and dive of KC-135 airplane.

  13. Vogel-Fulcher freezing in relaxor ferroelectrics

    SciTech Connect

    Pirc, R.; Blinc, R.

    2007-07-01

    A physical mechanism for the freezing of polar nanoregions (PNRs) in relaxor ferroelectrics is presented. Assuming that the activation energy for the reorientation of a cluster of PNRs scales with the mean volume of the cluster, the characteristic relaxation time {tau} is found to diverge as the cluster volume reaches the percolation limit. Applying the mean field theory of continuum percolation, the familiar Vogel-Fulcher equation for the temperature dependence of {tau} is derived.

  14. Freeze tolerance in an arctic Alaska stonefly.

    PubMed

    Walters, Kent R; Sformo, Todd; Barnes, Brian M; Duman, John G

    2009-01-01

    Most aquatic insects do not survive subzero temperatures and, for those that do, the physiology has not been well characterized. Nemoura arctica is a species of stonefly widely distributed throughout arctic and subarctic Alaska. We collected nymphs from the headwaters of the Chandalar River, where we recorded streambed temperatures as low as -12.7 degrees C in midwinter. When in contact with ice, autumn-collected N. arctica cool to -1.5+/-0.4 degrees C before freezing, but individuals survived temperatures as low as -15 degrees C, making this the first described species of freeze-tolerant stonefly. N. arctica clearly survive freezing in nature, as winter-collected nymphs encased in ice demonstrated high survivorship when thawed. In the laboratory, 87% of N. arctica nymphs frozen to -15 degrees C for 2.5 weeks survived and, within one month of thawing, 95% of the last-instar nymphs emerged. N. arctica produce both glycerol and ice-binding factors (e.g. antifreeze protein) in response to low temperature. Hemolymph glycerol concentrations increased from 3 mmol l(-1) to 930+/-114 mmol l(-1) when temperatures were decreased from 4 degrees C to -8 degrees C, and N. arctica continued to produce glycerol even while frozen. Although the hemolymph of individual cold-acclimated nymphs occasionally exhibited more than a degree of thermal hysteresis, typically the hemolymph exhibited only hexagonal crystal growth, indicating a low concentration of ice-binding factor. Hemolymph of nymphs acclimated to subzero temperatures had recrystallization inhibition. These results demonstrate that, in the face of freezing conditions, N. arctica exhibit overwintering adaptations similar to those of terrestrial insects. PMID:19112150

  15. Seasonal freeze resistance of rainbow smelt (Osmerus mordax) is generated by differential expression of glycerol-3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, and antifreeze protein genes.

    PubMed

    Liebscher, Ryan S; Richards, Robert C; Lewis, Johanne M; Short, Connie E; Muise, Denise M; Driedzic, William R; Ewart, K Vanya

    2006-01-01

    In winter, rainbow smelt (Osmerus mordax) accumulate glycerol and produce an antifreeze protein (AFP), which both contribute to freeze resistance. The role of differential gene expression in the seasonal pattern of these adaptations was investigated. First, cDNAs encoding smelt and Atlantic salmon (Salmo salar) phosphoenolpyruvate carboxykinase (PEPCK) and smelt glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were cloned so that all sequences required for expression analysis would be available. Using quantitative PCR, expression of beta actin in rainbow smelt liver was compared with that of GAPDH in order to determine its validity as a reference gene. Then, levels of glycerol-3-phosphate dehydrogenase (GPDH), PEPCK, and AFP relative to beta actin were measured in smelt liver over a fall-winter-spring interval. Levels of GPDH mRNA increased in the fall just before plasma glycerol accumulation, implying a driving role in glycerol synthesis. GPDH mRNA levels then declined during winter, well in advance of serum glycerol, suggesting the possibility of GPDH enzyme or glycerol conservation in smelt during the winter months. PEPCK mRNA levels rose in parallel with serum glycerol in the fall, consistent with an increasing requirement for amino acids as metabolic precursors, remained elevated for much of the winter, and then declined in advance of the decline in plasma glycerol. AFP mRNA was elevated at the onset of fall sampling in October and remained elevated until April, implying separate regulation from GPDH and PEPCK. Thus, winter freezing point depression in smelt appears to result from a seasonal cycle of GPDH gene expression, with an ensuing increase in the expression of PEPCK, and a similar but independent cycle of AFP gene expression. PMID:16555199

  16. Radiobrightness of diurnally heated, freezing soil

    NASA Technical Reports Server (NTRS)

    England, Anthony W.

    1990-01-01

    Freezing and thawing soils exhibit unique radiometric characteristics. To examine these characteristics, diurnal insolation is modeled as one-dimensional heating of a moist soil half-space during a typical fall at a northern Great Plains site. The one-dimensional heat flow equation is nonlinear because both the enthalpy (the change in internal energy with temperature at constant pressure) and the thermal conductivity of freezing soils are nonlinear functions of temperature. The problem is particularly difficult because phase boundaries propagate in time, and because soils, particularly clay-rich soils, freeze over a range of temperatures rather than at 0 C. Diurnal radiobrightness curves at 10.7, 18.0, and 37.0-GHz were computed for each month. The 37.0-GHz radiobrightness best tracks soil surface temperature; the 10.7-37.0-GHz spectral gradient of thawed soils is strongly positive; the spectral gradient of frozen soils is slightly negative; and the midnight-to-noon spectral gradient is shifted by approximately +0.1 K/GHz by diurnal changes in the surface temperature and the thermal gradient. These observations support the use of the scanning multichannel microwave radiometer 37.0-GHz radiobrightness and its 10.7-37.0-GHz spectral gradient as discriminants in a frozen soil classifier for high-latitude prairie.

  17. Human freezing in response to affective films.

    PubMed

    Hagenaars, Muriel A; Roelofs, Karin; Stins, John F

    2014-01-01

    Human freezing has been objectively assessed using a passive picture viewing paradigm as an analog for threat. These results should be replicated for other stimuli in order to determine their stability and generalizability. Affective films are used frequently to elicit affective responses, but it is unknown whether they also elicit freezing-like defense responses. To test whether this is the case, 50 participants watched neutral, pleasant and unpleasant film fragments while standing on a stabilometric platform and wearing a polar band to assess heart rate. Freezing-like responses (indicated by overall reduced body sway and heart rate deceleration) were observed for the unpleasant film only. The unpleasant film also elicited early reduced body sway (1-2 s after stimulus onset). Heart rate and body sway were correlated during the unpleasant film only. The results suggest that ecologically valid stimuli like films are adequate stimuli in evoking defense responses. The results also underscore the importance of including time courses in human experimental research on defense reactions in order to delineate different stages in the defense response. PMID:23805855

  18. Steam consumption reduction by eutectic freeze crystallization

    SciTech Connect

    Bichsel, S.E.; Cleary, M.; Barron, T.S.; Heist, J.A.

    1985-01-01

    Steam production in American beet sugar factories can be reduced by 600 pounds per ton of beets by using hydrate freeze crystallization in place of pan evaporators for sugar crystallization. This is a relatively constant number, regardless of current factory energy use. Further reduction is limited by the juice heating needs in the purification operations. Steam for juice heating is 20 to 30% on beets, or 400 to 600 pounds of steam per ton. In efficient factories this is about the steam flow to the evaporators when the pan crystallizers are replaced by freeze crystallization. An approach is described here for a rapid evaluation of effects on the steam balance of basic process changes. It provides a visual guide to restructuring the steam balance that simplifies optimization when such changes are made. The graphic approach is useful in illustrating methods of reducing energy use in a sugar factory, in addition to the current analysis of integration of the hydrate freeze process. For example, membrane and vapor recompression evaporators for juice concentration must be accompanied by major factory modifications to produce any net savings of steam. The reason is the needs for specific steam quantity and quality for the pan evaporators and juice heaters, supplied through the current evaporator trains. Reduction of the steam rate below 25 to 35% on beets will require changes to the conventional juice purification process.

  19. Anhedonia, Depressed Mood, and Smoking Cessation Outcome

    PubMed Central

    Leventhal, Adam M.; Piper, Megan E.; Japuntich, Sandra J.; Baker, Timothy B.; Cook, Jessica W.

    2014-01-01

    Objective Although the relation between lifetime depression and smoking cessation outcome has been well-studied, the proposition that different symptomatic expressions of depression exert disparate predictive effects on risk of smoking cessation failure has largely gone uninvestigated. This study analyzed the individual contributions of depression's two hallmark affective symptoms, anhedonia (i.e., diminished interest in normally enjoyable activities) and depressed mood (i.e., elevated sadness), to the prediction of smoking cessation outcome. Method Participants were adult daily smokers (N=1469; Mean age = 45 years, 58% Female, 84% White) enrolled in a smoking cessation treatment study. Lifetime history of anhedonia and depressed mood were classified via structured interview prior to quit day. Seven-day point prevalence smoking abstinence was assessed at 8-weeks and 6-months post-quit. Results When examined separately, both lifetime anhedonia, OR(95% CI)=1.42(1.16-1.73), p=.004, and depressed mood, OR(95% CI)=1.35(1.11-1.63), p=.002, predicted increased odds of relapse. These relations remained after adjusting for covariates, including lifetime depressive disorder, which did not predict outcome. After controlling for the covariation between lifetime anhedonia and depressed mood, anhedonia predicted cessation outcome, OR(95% CI)=1.31(1.05-1.62), p=.02, while depressed mood did not, p=.19. Symptom duration (>2 weeks), treatment, and substance use disorder did not modify relations of lifetime anhedonia and depressed mood with cessation outcome. Conclusions Results suggest that: (1) symptoms of affective disturbance capture depression-relevant risk of cessation failure, which is not adequately demarcated by the lifetime depressive disorder diagnosis; and (2) anhedonia is a more sensitive index of this affective disturbance than depressed mood per se. Clinical attention to anhedonia may facilitate smoking cessation. PMID:24219183

  20. Response of New zealand mudsnails Potamopyrgus antipodarum to freezing and near freezing fluctuating water temperatures

    USGS Publications Warehouse

    Moffitt, Christine M.; James, Christopher A.

    2012-01-01

    We explored the resilience of the invasive New Zealand mudsnail Potamopyrgus antipodarum to fluctuating winter freezing and near-freezing temperature cycles in laboratory tests. Our goal was to provide data to confirm field observations of mortality and presumed mortality in stream habitats with fluctuating freezing to near-freezing temperatures. We tested individuals from 2 locations with distinctly different thermal regimes and population densities. One location had low snail densities and water temperatures with strong diel and seasonal water variation. The other location had high snail densities and nearly constant water temperatures. Groups of individuals from both locations were tested in each of 3 laboratory-created diel thermal cycles around nominal temperatures of 0, 2, or 4°C. Mortality occurred in cycles around 0°C in both populations, and little to no mortality occurred at temperatures >0°C. Individuals from both sources held in diel 0°C cycles for 72 h showed 100% mortality. Our findings support observations from published field studies that survival was limited in infested habitats subject to freezing temperatures.

  1. Freeze-cast alumina pore networks: Effects of freezing conditions and dispersion medium

    SciTech Connect

    Miller, S. M.; Xiao, X.; Faber, K. T.

    2015-11-01

    Alumina ceramics were freeze-cast from water- and camphene-based slurries under varying freezing conditions and examined using X-ray computed tomography (XCT). Pore network characteristics, i.e., porosity, pore size, geometric surface area, and tortuosity, were measured from XCT reconstructions and the data were used to develop a model to predict feature size from processing conditions. Classical solidification theory was used to examine relationships between pore size, temperature gradients, and freezing front velocity. Freezing front velocity was subsequently predicted from casting conditions via the two-phase Stefan problem. Resulting models for water-based samples agreed with solidification-based theories predicting lamellar spacing of binary eutectic alloys, and models for camphene-based samples concurred with those for dendritic growth. Relationships between freezing conditions and geometric surface area were also modeled by considering the inverse relationship between pore size and surface area. Tortuosity was determined to be dependent primarily on the type of dispersion medium. (C) 2015 Elsevier Ltd. All rights reserved.

  2. Gullied Depression

    NASA Technical Reports Server (NTRS)

    2006-01-01

    26 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows gullies formed in the wall of a depression located on the floor of Rabe Crater west of the giant impact basin, Hellas Planitia. Gullies such as these are common features on Mars, but the process by which they are formed is not fully understood. The debate centers on the role and source of fluids in the genesis of these features.

    Location near: 44.1oS, 325.9oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  3. Aquaporin expression correlates with freeze tolerance in baker's yeast, and overexpression improves freeze tolerance in industrial strains.

    PubMed

    Tanghe, An; Van Dijck, Patrick; Dumortier, Françoise; Teunissen, Aloys; Hohmann, Stefan; Thevelein, Johan M

    2002-12-01

    Little information is available about the precise mechanisms and determinants of freeze resistance in baker's yeast, Saccharomyces cerevisiae. Genomewide gene expression analysis and Northern analysis of different freeze-resistant and freeze-sensitive strains have now revealed a correlation between freeze resistance and the aquaporin genes AQY1 and AQY2. Deletion of these genes in a laboratory strain rendered yeast cells more sensitive to freezing, while overexpression of the respective genes, as well as heterologous expression of the human aquaporin gene hAQP1, improved freeze tolerance. These findings support a role for plasma membrane water transport activity in determination of freeze tolerance in yeast. This appears to be the first clear physiological function identified for microbial aquaporins. We suggest that a rapid, osmotically driven efflux of water during the freezing process reduces intracellular ice crystal formation and resulting cell damage. Aquaporin overexpression also improved maintenance of the viability of industrial yeast strains, both in cell suspensions and in small doughs stored frozen or submitted to freeze-thaw cycles. Furthermore, an aquaporin overexpression transformant could be selected based on its improved freeze-thaw resistance without the need for a selectable marker gene. Since aquaporin overexpression does not seem to affect the growth and fermentation characteristics of yeast, these results open new perspectives for the successful development of freeze-resistant baker's yeast strains for use in frozen dough applications. PMID:12450819

  4. Depression's forgotten genealogy: notes towards a history of depression.

    PubMed

    Rousseau, G

    2000-03-01

    The history of depression remains unwritten, yet historians harbor plentiful assumptions about its pre-1800 past. These views are necessarily colored, even shaped, by modern views of depression formed after its nineteenth-century medicalization. A history of depression from ancient to modern times is an impossible task to complete successfully and would require, as a minimum, the historian's utmost vigilance to nuance, difference, and the inclusion of non-medical literature, especially poetry, drama and non-didactic prose. Nevertheless, five points about depression's pre-1800 European profile can confidently be made: (1) it developed along lines of female rather than male gender; (2) was transformed in the long eighteenth century when it blended with male madness under the sway of the cults of a pan-European sensibility movement; (3) always embedded a problematic pseudo-depressive state, or feigned version, which acted to permit female escape from dire socio-economic situation; (4) included sustained chronic duration as a requirement in its theory from the Renaissance forward; (5) is richly documented in its pre-1800 versions in imaginative literature, its often overlooked genealogy. PMID:11624608

  5. Freeze-Thaw Injury to Isolated Spinach Protoplasts and Its Simulation at Above Freezing Temperatures 1

    PubMed Central

    Wiest, Steven C.; Steponkus, Peter L.

    1978-01-01

    Possibilities to account for the mechanism of freeze-thaw injury to isolated protoplasts of Spinacia oleracea L. cv. Winter Bloomsdale were investigated. A freeze-thaw cycle to ?3.9 C resulted in 80% lysis of the protoplasts. At ?3.9 C, protoplasts are exposed to the equivalent of a 2.1 osmolal solution. Isolated protoplasts behave as ideal osmometers in the range of concentrations tested (0.35 to 2.75 osmolal), arguing against a minimum critical volume as a mechanism of injury. Average protoplast volume after a freeze-thaw cycle was not greatly different than the volume before freezing, arguing against an irreversible influx of solutes while frozen. A wide variety of sugars and sugar alcohols, none of which was freely permeant, were capable of protecting against injury which occurred when protoplasts were frozen in salt solutions. The extent of injury was also dependent upon the type of monovalent ions present, with Li = Na > K = Rb = Cs and Cl ? Br > I, in order of decreasing protoplast survival. Osmotic conditions encountered during a freeze-thaw cycle were established at room temperature by exposing protoplasts to high salt concentrations and then diluting the osmoticum. Injury occurred only after dilution of the osmoticum and was correlated with the expansion of the plasma membrane. Injury observed in frozen-thawed protoplasts was correlated with the increase in surface area the plasma membrane should have undergone during thawing, supporting the contention that contraction of the plasma membrane during freezing and its expansion during thawing are two interacting lesions which cause protoplast lysis during a freezethaw cycle. PMID:16660588

  6. Variation of the average 'freezing-in' temperature of oxygen ions with solar wind speed

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Vogt, C.

    1980-01-01

    Observations of the average oxygen ionization equilibrium as a function of speed of the solar wind are presented. At low solar wind speeds they indicate a coronal temperature at the freezing-in point of (1.6 + or - 0.2) x 10 to the 6th K. At speeds above 450 km/sec the apparent temperature starts to rise rapidly. This rise is tentatively interpreted in terms of a lack of thermodynamic equilibrium in the source region.

  7. Transmembrane ion distribution during recovery from freezing in the woolly bear caterpillar Pyrrharctia isabella (Lepidoptera: Arctiidae).

    PubMed

    Boardman, Leigh; Terblanche, John S; Sinclair, Brent J

    2011-08-01

    During extracellular freezing, solutes in the haemolymph are concentrated, resulting in osmotic dehydration of the cells, which must be reversed upon thawing. Here, we used freeze tolerant Pyrrharctia isabella (Lepidoptera: Arctiidae) larvae to examine the processes of ion redistribution after thawing. To investigate the effect of the intensity of cold exposure on ion redistribution after thawing, we exposed caterpillars to -14°C, -20°C or -30°C for 35h. To investigate the effect of duration of cold exposure on ion redistribution after thawing, we exposed the caterpillars to -14°C for up to 6 weeks while sampling several time points. The concentrations of Na(+), K(+), Mg(2+) and Ca(2+) were measured after thawing in the haemolymph, fat body, muscle, midgut tissue and hindgut tissue. Being frozen for long durations (>3 weeks) or at low temperatures (-30°C) both result in 100% mortality, although different ions and tissues appear to be affected by each treatment. Both water distribution and ion content changes were detected after thawing, with the largest effects seen in the fat body and midgut tissue. Magnesium homeostasis appears to be vital for post-freeze survival in these larvae. The movement of ions during thawing lagged behind the movement of water, and ion homeostasis was not restored within the same time frame as water homeostasis. Failure to regain ion homeostasis after thawing is therefore implicated in mortality of freeze tolerant insects. PMID:21575641

  8. How to freeze drop oscillations with powders

    NASA Astrophysics Data System (ADS)

    Marston, Jeremy; Zhu, Ying; Vakarelski, Ivan; Thoroddsen, Sigurdur

    2012-11-01

    We present experiments that show when a water drop impacts onto a bed of fine, hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. For all drop impact speeds, the drop rebounds due to the hydrophobic nature of the powder. However, we observe that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a complete coverage of powder, thus creating a deformed liquid marble. This powder coating acts to freeze the drop oscillations during rebound.

  9. Freeze Tolerant Radiator for an Advanced EMU

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  10. Freezing distributed entanglement in spin chains

    SciTech Connect

    D'Amico, Irene; Lovett, Brendon W.; Spiller, Timothy P.

    2007-09-15

    We show how to freeze distributed entanglement that has been created from the natural dynamics of spin chain systems. The technique that we propose simply requires single-qubit operations and isolates the entanglement in specific qubits at the ends of branches. Such frozen entanglement provides a useful resource, for example for teleportation or distributed quantum processing. The scheme can be applied to a wide range of systems--including actual spin systems and alternative qubit embodiments in strings of quantum dots, molecules, or atoms.

  11. Freeze-drying of live virus vaccines: A review.

    PubMed

    Hansen, L J J; Daoussi, R; Vervaet, C; Remon, J-P; De Beer, T R M

    2015-10-13

    Freeze-drying is the preferred method for stabilizing live, attenuated virus vaccines. After decades of research on several aspects of the process like the stabilization and destabilization mechanisms of the live, attenuated viruses during freeze-drying, the optimal formulation components and process settings are still matter of research. The molecular complexity of live, attenuated viruses, the multiple destabilization pathways and the lack of analytical techniques allowing the measurement of physicochemical changes in the antigen's structure during and after freeze-drying mean that they form a particular lyophilization challenge. The purpose of this review is to overview the available information on the development of the freeze-drying process of live, attenuated virus vaccines, herewith focusing on the freezing and drying stresses the viruses can undergo during processing as well as on the mechanisms and strategies (formulation and process) that are used to stabilize them during freeze-drying. PMID:26364685

  12. High-pressure freezing and freeze substitution of Arabidopsis for electron microscopy.

    PubMed

    Austin, Jotham R

    2014-01-01

    The objectives of electron microscopy ultrastructural studies are to examine cellular architecture and relate the cell's structural machinery to dynamic functional roles. This aspiration is difficult to achieve if specimens have not been adequately preserved in a "living state"; hence specimen preparation is of the utmost importance for the success of any electron micrographic study. High-pressure freezing (HPF)/freeze substitution (FS) has long been recognized as the primer technique for the preservation of ultrastructure in biological samples. In most cases a basic HPF/freeze substitution protocol is sufficient to obtain superior ultrastructural preservation and structural contrast, which allows one to use more advanced microscopy techniques such as 3D electron tomography. However, for plant tissues, which have a thick cell wall, large water-filled vacuoles, and air spaces (all of which are detrimental to cryopreservation), these basic HPF/FS protocols often yield undesirable results. In particular, ice crystal artifacts and the staining of membrane systems are often poorly or negatively stained, which make 3D segmentation of a tomogram difficult. To overcome these problems, various aspects of the HPF/FS protocol can be altered, including the cryo-filler(s) used, freeze substitution cocktail, and the resin infiltration process. This chapter will describe these modifications for the preparation of plant tissues for routine electron microscopic studies, immunocytochemistry, and 3D tomographic electron imaging. PMID:24057382

  13. Retarded condensate freezing propagation on superhydrophobic surfaces patterned with micropillars

    NASA Astrophysics Data System (ADS)

    Zhao, Yugang; Yang, Chun

    2016-02-01

    Previous studies have shown ice delay on nano-structured or hierarchical surfaces with nanoscale roughness. Here we report retarded condensate freezing on superhydrophobic silicon substrates fabricated with patterned micropillars of small aspect ratio. We further investigated the pillar size effects on freezing propagation. We found that the velocity of freezing propagation on the surface patterned with proper micropillars can be reduced by one order of magnitude, compared to that on the smooth untreated silicon surface. Additionally, we developed an analytical model to describe the condensate freezing propagation on a structured surface with micropillars and the model predictions were compared with our experimental results.

  14. Reversible Photoinhibition in Antarctic Moss during Freezing and Thawing.

    PubMed

    Lovelock, C. E.; Jackson, A. E.; Melick, D. R.; Seppelt, R. D.

    1995-11-01

    Tolerance of antarctic moss to freezing and thawing stress was investigated using chlorophyll a fluorescence. Freezing in darkness caused reductions in Fv/Fm (ratio of variable to maximum fluorescence) and Fo (initial fluorescence) that were reversible upon thawing. Reductions in Fv/Fm and Fo during freezing in darkness indicate a reduction in the potential efficiency of photosystem II that may be due to conformational changes in pigment-protein complexes due to desiccation associated with freezing. The absorption of light during freezing further reduced Fv/Fm and Fo but was also reversible. Using dithiothreitol (DTT), which inhibits the formation of the carotenoid zeaxanthin, we found reduced flurorescence quenching during freezing and reduced concentrations of zeaxanthin and antheraxanthin after freezing in DTT-treated moss. Reduced concentrations of zeaxanthin and antheraxanthin in DTT-treated moss were partially associated with reductions in nonphotochemical fluorescence quenching. The reversible photoinhibition observed in antarctic moss during freezing indicates the existence of processes that protect from photoinhibitory damage in environments where freezing temperatures occur in conjunction with high solar radiation levels. These processes may limit the need for repair cycles that require temperatures favorable for enzyme activity. PMID:12228644

  15. Design of a blood-freezing system for leukemia research

    NASA Technical Reports Server (NTRS)

    Williams, T. E.; Cygnarowicz, T. A.

    1978-01-01

    Leukemia research involves the use of cryogenic freezing and storage equipment. In a program being carried out at the National Cancer Institute (NCI), bone marrow (white blood cells) was frozen using a standard cryogenic biological freezer. With this system, it is difficult to maintain the desired rate of freezing and repeatability from sample to sample. A freezing system was developed that satisfies the requirements for a repeatable, constant freezing rate. The system was delivered to NIC and is now operational. This report describes the design of the major subsystems, the analyses, the operating procedure, and final system test results.

  16. A molecular dynamics study of freezing in a confined geometry

    NASA Technical Reports Server (NTRS)

    Ma, Wen-Jong; Banavar, Jayanth R.; Koplik, Joel

    1992-01-01

    The dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls is studied by computer simulation. The time development of ordering is quantified and a novel freezing mechanism is observed. The liquid forms layers and subsequent in-plane ordering within a layer is accompanied by a sharpening of the layer in the transverse direction. The effects of channel size, the methods of quench, the liquid-wall interaction and the roughness of walls on the freezing mechanism are elucidated. Comparison with recent experiments on freezing in confined geometries is presented.

  17. Associations among Smoking, Anhedonia, and Reward Learning in Depression

    PubMed Central

    Liverant, Gabrielle I.; Sloan, Denise M.; Pizzagalli, Diego A.; Harte, Christopher B.; Kamholz, Barbara W.; Rosebrock, Laina E.; Cohen, Andrew L.; Fava, Maurizio; Kaplan, Gary B.

    2015-01-01

    Depression and cigarette smoking co-occur at high rates. However, the etiological mechanisms that contribute to this relationship remain unclear. Anhedonia and associated impairments in reward learning are key features of depression, which also have been linked to the onset and maintenance of cigarette smoking. However, few studies have investigated differences in anhedonia and reward learning among depressed smokers and depressed nonsmokers. The goal of this study was to examine putative differences in anhedonia and reward learning in depressed smokers (n = 36) and depressed nonsmokers (n = 44). To this end, participants completed self-report measures of anhedonia and behavioral activation (BAS reward responsiveness scores) and as well as a probabilistic reward task rooted in signal detection theory, which measures reward learning (Pizzagalli, Jahn, & O’Shea, 2005). When considering self-report measures, depressed smokers reported higher trait anhedonia and reduced BAS reward responsiveness scores compared to depressed nonsmokers. In contrast to self-report measures, nicotine-satiated depressed smokers demonstrated greater acquisition of reward-based learning compared to depressed nonsmokers as indexed by the probabilistic reward task. Findings may point to a potential mechanism underlying the frequent co-occurrence of smoking and depression. These results highlight the importance of continued investigation of the role of anhedonia and reward system functioning in the co-occurrence of depression and nicotine abuse. Results also may support the use of treatments targeting reward learning (e.g., behavioral activation) to enhance smoking cessation among individuals with depression. PMID:25022776

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 m 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 C 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

  19. Fundamental Boiling and RP-1 Freezing Experiments

    NASA Technical Reports Server (NTRS)

    Goode, Brian; Turner, Larry D. (Technical Monitor)

    2001-01-01

    This paper describes results from experiments performed to help understand certain aspects of the MC-1 engine prestart thermal conditioning procedure. The procedure was constrained by the fact that the engine must chill long enough to get quality LOX at the LOX pump inlet but must be short enough to prevent freezing of RP-1 in the fuel pump. A chill test of an MC-1 LOX impeller was performed in LN2 to obtain data on film boiling, transition boiling and impeller temperature histories. The transition boiling data was important to the chill time so a subsequent experiment was performed chilling simple steel plates in LOX to obtain similar data for LOX. To address the fuel freezing concern, two experiments were performed. First, fuel was frozen in a tray and its physical characteristics were observed and temperatures of the fuel were measured. The result was physical characteristics as a function of temperature. Second was an attempt to measure the frozen thickness of RP-1 on a cold wall submerged in warm RP-1 and to develop a method for calculating that thickness for other conditions.

  20. Morphological study of endothelial cells during freezing.

    PubMed

    Zhang, A; Xu, L X; Sandison, G A; Cheng, S

    2006-12-01

    Microvascular injury is recognized as a major tissue damage mechanism of ablative cryosurgery. Endothelial cells lining the vessel wall are thought to be the initial target of freezing. However, details of this injury mechanism are not yet completely understood. In this study, ECMatrix 625 was used to mimic the tumour environment and to allow the endothelial cells cultured in vitro to form the tube-like structure of the vasculature. The influence of water dehydration on the integrity of this structure was investigated. It was found that the initial cell shape change was mainly controlled by water dehydration, dependent on the cooling rate, resulting in the shrinkage of cells in the direction normal to the free surface. As the cooling was prolonged and temperature was lowered, further cell shape change could be induced by the chilling effects on intracellular proteins, and focal adhesions to the basement membrane. Quantitative analysis showed that the freezing induced dehydration greatly enhanced the cell surface stresses, especially in the axial direction. This could be one of the major causes of the final breaking of the cell junction and cell detachment. PMID:17110769

  1. Expression of freeze-responsive proteins, Fr10 and Li16, from freeze-tolerant frogs enhances freezing survival of BmN insect cells.

    PubMed

    Biggar, Kyle K; Kotani, Eiji; Furusawa, Toshiharu; Storey, Kenneth B

    2013-08-01

    To date, two novel freeze-responsive proteins, Fr10 and Li16, have been discovered in the wood frog, Rana sylvatica, and likely support freezing survival. Although previous studies have established tissue distribution of each protein, there have been no studies that explore their functional consequences in intolerant cells. To assess the ability of Fr10 and Li16 to confer freeze tolerance, we transfected each protein into a freeze-intolerant silkworm cell line (BmN). Selected controls were the transfection of an unrelated protein (CAT) and a no-transfection sample. Li16 and Fr10 showed 1.8 ± 0.1- and 1.7 ± 0.2-fold, respectively, greater survival after freezing at -6°C for 1 h than did transfection controls. To investigate how these novel proteins protect cells from freezing damage, protein structures were predicted from primary amino acid sequences. Analysis of the structures indicated that Fr10 is a secreted protein and may be a new type IV antifreeze protein, whereas Li16 may have intracellular membrane associated functions. This study shows that freezing protection can be provided to intolerant cells by the overexpression of transfected Li16 and Fr10 frog proteins. Results from this study will provide new insights into adapting intolerant cells for medical organ cryoprotection using a natural vertebrate model of tolerance. PMID:23657819

  2. Effect of repeated freeze-thaw cycles on geographically different populations of the freeze-tolerant worm Enchytraeus albidus (Oligochaeta).

    PubMed

    Fisker, Karina Vincents; Holmstrup, Martin; Malte, Hans; Overgaard, Johannes

    2014-11-01

    Freeze-tolerant organisms survive internal ice formation; however, the adaptations to repeated freeze-thaw cycles are often not well investigated. Here we report how three geographically different populations of Enchytraeus albidus (Germany, Iceland and Svalbard) respond to three temperature treatments - constant thawed (0C), constant freezing (-5C) and fluctuating temperature (0 to -5C) - over a period of 42 days. Survival varied between treatments and populations such that enchytraeids from arctic locations had a higher survival following prolonged freeze periods compared with temperate populations. However, enchytraeids from temperate locations had the same survival rate as arctic populations when exposed to repeated freeze-thaw events. Across all populations, metabolic rate decreased markedly in frozen animals (-5C) compared with thawed controls (0C). This decrease is likely due to the lower temperature of frozen animals, but also to the transition to the frozen state per se. Animals exposed to repeated freeze-thaw events had an intermediate metabolic rate and freeze-thaw events were not associated with pronounced excess energetic costs. Overwintering under either condition was not associated with a decrease in lipid content; however, during exposure to constant freezing and repeated freeze-thaw events there was a noticeable decrease in carbohydrate stores over time. Thus, animals exposed to constant freezing showed a decrease in glycogen stores, while both glucose and glycogen content decreased over time when the organisms were exposed to repeated freezing. The results therefore suggest that carbohydrate resources are important as a fuel for E. albidus during freezing whereas lipid resources are of marginal importance. PMID:25214492

  3. Spray-freeze-drying production of thermally sensitive polymeric nanoparticle aggregates for inhaled drug delivery: effect of freeze-drying adjuvants.

    PubMed

    Cheow, Wean Sin; Ng, Mabel Li Ling; Kho, Katherine; Hadinoto, Kunn

    2011-02-14

    Inhalable dry-powder aggregates of drug-loaded thermally sensitive poly(caprolactone) (PCL) nanoparticles are produced using spray-freeze-drying (SFD) as the low melting point of PCL prohibits the use of high-temperature spray-drying. The effects of freeze-drying adjuvant formulation on the particle morphology, aerodynamic diameter, aqueous re-dispersibility, flowability, and production yield are examined using mannitol and poly(vinyl alcohol) (PVA) as the adjuvants. The primary role of the adjuvant is to prevent irreversible nanoparticle coalescences during freeze-drying, thereby the nanoparticle aggregates can readily re-disperse into primary nanoparticles in an aqueous environment hence retaining their therapeutic functions. The nanoparticle aggregates produced using either adjuvant exhibit large, porous, and spherical morphologies suitable for dry-powder-inhaler delivery. The nanoparticle aggregates exhibit good flowability and effective aerosolization off the inhaler. The adjuvant selection governs the resultant nanoparticle-adjuvant structures, where PCL nanoparticles are physically dispersed in porous mannitol matrix, whereas PVA are coated onto the nanoparticle surface. Importantly, nanoparticle aggregates produced by SFD exhibit significantly higher aqueous re-dispersibility than those produced by spray-drying, which signifies the suitability of SFD as the method to produce solid-dosage-form of thermally sensitive nanoparticles. Overall, using PVA as adjuvant leads to more stable morphology, superior aqueous re-dispersibility, and higher production yield compared to the mannitol formulation. PMID:21093560

  4. Poststroke Depression: A Review

    PubMed Central

    Robinson, Robert G.; Spalletta, Gianfranco

    2013-01-01

    Objective To review the worlds (English-language) publications related to depression following stroke. Method The databases from MEDLINE and PubMed were reviewed for articles related to poststroke depression (PSD), depression and cerebral vascular accident, depression and cerebral vascular disease, and depression and cerebral infarction. Results Most studies examined prevalence rates of depression and the clinical correlates of depression. Based on pooled data, the overall prevalence of major depression was 21.7% and minor depression was 19.5%. The strongest single correlate of depression was severity of impairment in activities of daily living. However, the existence of depression at baseline was found to be associated with greater impairment at follow-up, ranging from 6 weeks to 2 years in 83% of studies. Further, depression following acute stroke was also associated with greater cognitive impairment and increased mortality. PSD has been shown in 6 double-blind controlled studies to be effectively treated with antidepressants, and 1 study has recently shown that PSD can be effectively prevented. Conclusions During the past 20 years, significant progress has been made in the identification and treatment of depression following stroke. In the future, antidepressant treatment will likely play an increasing role in the management of patients with acute stroke. Further research is needed to identify the mechanisms of depression and why antidepressants lead to improved physical and cognitive recovery and decreased mortality. PMID:20540828

  5. A historical perspective on cold tolerance in the Canal Point Sugarcane Breeding Program

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Developing sugarcane cultivars with greater freeze tolerance is an important objective of the USDA-ARS Canal Point breeding program, as temperatures around -3oC (27oF) cause serious sugar yield losses during the harvest season. To estimate if progress was made in freeze tolerance by breeding for can...

  6. Motor Imagery in Unipolar Major Depression

    PubMed Central

    Bennabi, Djamila; Monnin, Julie; Haffen, Emmanuel; Carvalho, Nicolas; Vandel, Pierre; Pozzo, Thierry; Papaxanthis, Charalambos

    2014-01-01

    Background: Motor imagery is a potential tool to investigate action representation, as it can provide insights into the processes of action planning and preparation. Recent studies suggest that depressed patients present specific impairment in mental rotation. The present study was designed to investigate the influence of unipolar depression on motor imagery ability. Methods: Fourteen right-handed patients meeting DSM-IV criteria for unipolar depression were compared to 14 matched healthy controls. Imagery ability was accessed by the timing correspondence between executed and imagined movements during a pointing task, involving strong spatiotemporal constraints (speed/accuracy trade-off paradigm). Results: Compared to controls, depressed patients showed marked motor slowing on both actual and imagined movements. Furthermore, we observed greater temporal discrepancies between actual and mental movements in depressed patients than in healthy controls. Lastly, depressed patients modulated, to some extent, mental movement durations according to the difficulty of the task, but this modulation was not as strong as that of healthy subjects. Conclusion: These results suggest that unipolar depression significantly affects the higher stages of action planning and point out a selective decline of motor prediction. PMID:25538580

  7. In-line multipoint near-infrared spectroscopy for moisture content quantification during freeze-drying.

    PubMed

    Kauppinen, Ari; Toiviainen, Maunu; Korhonen, Ossi; Aaltonen, Jaakko; Järvinen, Kristiina; Paaso, Janne; Juuti, Mikko; Ketolainen, Jarkko

    2013-02-19

    During the past decade, near-infrared (NIR) spectroscopy has been applied for in-line moisture content quantification during a freeze-drying process. However, NIR has been used as a single-vial technique and thus is not representative of the entire batch. This has been considered as one of the main barriers for NIR spectroscopy becoming widely used in process analytical technology (PAT) for freeze-drying. Clearly it would be essential to monitor samples that reliably represent the whole batch. The present study evaluated multipoint NIR spectroscopy for in-line moisture content quantification during a freeze-drying process. Aqueous sucrose solutions were used as model formulations. NIR data was calibrated to predict the moisture content using partial least-squares (PLS) regression with Karl Fischer titration being used as a reference method. PLS calibrations resulted in root-mean-square error of prediction (RMSEP) values lower than 0.13%. Three noncontact, diffuse reflectance NIR probe heads were positioned on the freeze-dryer shelf to measure the moisture content in a noninvasive manner, through the side of the glass vials. The results showed that the detection of unequal sublimation rates within a freeze-dryer shelf was possible with the multipoint NIR system in use. Furthermore, in-line moisture content quantification was reliable especially toward the end of the process. These findings indicate that the use of multipoint NIR spectroscopy can achieve representative quantification of moisture content and hence a drying end point determination to a desired residual moisture level. PMID:23351045

  8. A new approach for freezing of aqueous solutions under active control of the nucleation temperature.

    PubMed

    Petersen, Ansgar; Schneider, Hendrik; Rau, Guenter; Glasmacher, Birgit

    2006-10-01

    An experimental setup for controlled freezing of aqueous solutions is introduced. The special feature is a mechanism to actively control the nucleation temperature via electrofreezing: an ice nucleus generated at a platinum electrode by the application of an electric high voltage pulse initiates the crystallization of the sample. Using electrofreezing, the nucleation temperature in pure water can be precisely adjusted to a desired value over the whole temperature range between a maximum temperature Tn(max) close to the melting point and the temperature of spontaneous nucleation. However, the presence of additives can inhibit the nucleus formation. The influence of hydroxyethylstarch (HES), glucose, glycerol, additives commonly used in cryobiology, and NaCl on Tn(max) were investigated. While the decrease showed to be moderate for the non-ionic additives, the hindrance of nucleation by ionic NaCl makes the direct application of electrofreezing in solutions with physiological salt concentrations impossible. Therefore, in the multi-sample freezing device presented in this paper, the ice nucleus is produced in a separate volume of pure water inside an electrode cap. This way, the nucleus formation becomes independent of the sample composition. Using electrofreezing rather than conventional seeding methods allows automated freezing of many samples under equal conditions. Experiments performed with model solutions show the reliability and repeatability of this method to start crystallization in the test samples at different specified temperatures. The setup was designed to freeze samples of small volume for basic investigations in the field of cryopreservation and freeze-drying, but the mode of operation might be interesting for many other applications where a controlled nucleation of aqueous solutions is of importance. PMID:16887112

  9. [Emotional reactivity of patients with depression].

    PubMed

    Mikhaĭlova, E S; Monosova, A Zh; Beliaev, B S

    1990-01-01

    Emotional reactivity of patients with endogenous depression and healthy test subjects towards classic and rock music was compared. According to the questionnaire data and EEG recording, it was established that in depressed patients, analysis and estimation of the emotionally significant information differ from those in healthy persons. In contrast to normals, the classic music exerts an activation effect on the patients whereas rock music evokes negative emotions. Analysis of the time-course of changes in the EEG points to alterations in the system of nonspecific activation in depressions. PMID:2167595

  10. Freezing survival, body ice content and blood composition of the freeze-tolerant European common lizard, Lacerta vivipara.

    PubMed

    Voituron, Y; Storey, J M; Grenot, C; Storey, K B

    2002-01-01

    To investigate the freeze tolerance of the European common lizard, Lacerta vivipara, we froze 17 individuals to body temperatures as low as -4 degrees C under controlled laboratory conditions. The data show that this species tolerates the freezing of 50% of total body water and can survive freezing exposures of at least 24-h duration. Currently, this represents the best known development of freeze tolerance among squamate reptiles. Freezing stimulated a significant increase in blood glucose levels (16.15+/- 1.73 micromol x ml(-1) for controls versus 25.06 +/- 2.92 micromol x ml(-1) after thawing) but this increase had no significant effect on serum osmolality which was unchanged between control and freeze-exposed lizards (506.0 +/- 23.8 mosmol x l(-1) versus 501.0 +/- 25.3 mosmol x l(-1), respectively). Tests that assessed the possible presence of antifreeze proteins in lizard blood were negative. Recovery at 5 degrees C after freezing was assessed by measurements of the mean time for the return of breathing (5.9 +/- 0.5 h) and of the righting reflex (44.8 +/- 4.5 h). Because this species hibernates in wet substrates inoculative freezing may frequently occur in nature and the substantial freeze tolerance of this lizard should play a key role in its winter survival. PMID:11824405

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

    PubMed

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

    2012-11-20

    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 ΦX174 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

  12. Increased spring freezing vulnerability for alpine shrubs under early snowmelt.

    PubMed

    Wheeler, J A; Hoch, G; Corts, A J; Sedlacek, J; Wipf, S; Rixen, C

    2014-05-01

    Alpine dwarf shrub communities are phenologically linked with snowmelt timing, so early spring exposure may increase risk of freezing damage during early development, and consequently reduce seasonal growth. We examined whether environmental factors (duration of snow cover, elevation) influenced size and the vulnerability of shrubs to spring freezing along elevational gradients and snow microhabitats by modelling the past frequency of spring freezing events. We sampled biomass and measured the size of Salix herbacea, Vaccinium myrtillus, Vaccinium uliginosum and Loiseleuria procumbens in late spring. Leaves were exposed to freezing temperatures to determine the temperature at which 50% of specimens are killed for each species and sampling site. By linking site snowmelt and temperatures to long-term climate measurements, we extrapolated the frequency of spring freezing events at each elevation, snow microhabitat and per species over 37 years. Snowmelt timing was significantly driven by microhabitat effects, but was independent of elevation. Shrub growth was neither enhanced nor reduced by earlier snowmelt, but decreased with elevation. Freezing resistance was strongly species dependent, and did not differ along the elevation or snowmelt gradient. Microclimate extrapolation suggested that potentially lethal freezing events (in May and June) occurred for three of the four species examined. Freezing events never occurred on late snow beds, and increased in frequency with earlier snowmelt and higher elevation. Extrapolated freezing events showed a slight, non-significant increase over the 37-year record. We suggest that earlier snowmelt does not enhance growth in four dominant alpine shrubs, but increases the risk of lethal spring freezing exposure for less freezing-resistant species. PMID:24435708

  13. Preliminary trial: motility comparisons of a unique freezing technology (UFT) to liquid nitrogen mist methodology for cryopreservation of porcine spermatozoa.

    PubMed

    Goolsby, H A; Blanton, J R; Cotter, P Z; Prien, S D

    2004-10-01

    The motility outcomes of boar semen frozen with newly developed freezing techniques using a new unique freezing technology (UFT) compared with traditional liquid nitrogen methodology were investigated with the intent of improving current fertility outcomes using semen. The UFT is an electronically controlled cooling chamber that houses an organic fluid bath that can be maintained at temperatures below 0 degrees C without solidifying to freeze samples. Four ejaculates from four different boars were collected for this trial. Samples were handled consistently during the pre- and post-freeze processing. From each ejaculate, samples were separated into eight cryopreservation treatment groups, six UFT variations and two control liquid nitrogen groups, immediately before freezing, in replicates of two. After the initial cryopreservation was complete, all samples were stored in liquid nitrogen for at least 48 h. Post-thaw motilities and original motility return percentages were assessed on a random, individual-sample basis. After the initial evaluations, samples from two boars were recollected and frozen using the UFT for breeding purposes. Four sows were bred with the UFT frozen semen to confirm fertility capability. When assessing the individual UFT techniques, all of six UFT techniques had improved post-thaw motilities. However, treatments F (micro = 29%, return micro = 37%) and J (micro = 27%, return micro = 34%) showed the highest statistical improvement for post-thaw (p < 0.05) and original motility percent returns (p < 0.05) when compared with either the control cryo-tube (micro = 15%, return micro = 19%) or straw groups (micro = 12%, return micro = 16%). The UFT semen had a 50% conception rate, with an average of seven piglets from the sows that farrowed. Our preliminary data suggest a higher motility return with a slower pre-freeze phase below the freezing point before the acceleration to liquid nitrogen temperatures. The preliminary data suggest that the UFT could be utilized as a potential cryopreservation option for boar semen. PMID:15367265

  14. Summer freezing resistance decreased in high-elevation plants exposed to experimental warming in the central Chilean Andes.

    PubMed

    Sierra-Almeida, Angela; Cavieres, Lohengrin A

    2010-05-01

    Alpine habitats have been proposed as particularly sensitive to climate change. Shorter snow cover could expose high-elevation plants to very low temperatures, increasing their risk of suffering damage by freezing, hence decreasing their population viability. In addition, a longer and warmer growing season could affect the hardening process on these species. Thus, understanding the ability of these species to withstand freezing events under warmer conditions is essential for predicting how alpine species may respond to future climate changes. Here we assessed the freezing resistance of 11 species from the central Chilean Andes by determining their low temperature damage (LT(50)) and freezing point (FP) after experimental warming in the field. Plants were exposed during two growing seasons to a passive increase in the air temperature using open top chambers (OTCs). OTCs increased by ca. 3 K the mean air and soil daytime temperatures, but had smaller effects on freezing temperatures. Leaf temperature of the different species was on average 5.5 K warmer inside OTCs at midday. While LT(50) of control plants ranged from -9.9 to -22.4, that of warmed plants ranged from -7.4 to -17.3 degrees C. Overall, high-Andean species growing inside OTCs increased their LT(50) ca. 4 K, indicating that warming decreased their ability to survive severe freezing events. Moreover, plants inside OTCs increased the FP ca. 2 K in some studied species, indicating that warming altered processes of ice crystal formation. Resistance of very low temperatures is a key feature of high-elevation species; our results suggest that current climate warming trends will seriously threaten the survival of high-elevation plants by decreasing their ability to withstand severe freezing events. PMID:20237942

  15. Interplay between demixing and freezing in two-dimensional symmetrical mixtures.

    PubMed

    Patrykiejew, A; Sokołowski, S

    2010-01-01

    The interplay between demixing and freezing in two-dimensional symmetrical binary mixtures of Lennard-Jones particles is studied using Monte Carlo simulation. It is demonstrated that different scenarios are possible. For example, the line of continuous liquid demixing transition can start at the liquid side of the vapor-liquid coexistence at the lower critical end point and then it can terminate at the liquid side of the liquid-demixed solid coexistence at the upper critical end point. Other situations are also possible. We distinguish four different scenarios depending on the interactions between unlike particles. PMID:20365417

  16. Thermal conductivity measurements in phase change materials under freezing in presence of nanoinclusions

    NASA Astrophysics Data System (ADS)

    Angayarkanni, S. A.; Philip, John

    2015-09-01

    We study the thermal properties and internal microstructures of n-hexadecane alkane containing nanoinclusions of copper nanowire, multi walled carbon nanotube, and graphene nanoplatelets of different volume fractions. Just below the freezing point, a large thermal contrast is observed in all the three systems. The thermal conductivity decreases with temperature below the freezing temperature and stabilizes at ˜10 °C below the freezing point. More than 100% of thermal conductivity enhancement is observed with 0.01 wt. % of nanofillers during the liquid to solid phase change. It is speculated that the reduction in the interfacial thermal resistance and the internal stress generated during the first order phase transition, due to the presence of nanoinclusions at grain boundaries of alkane crystals, led to the observed increase in the thermal conductivity. We found that an optimal nanoparticle loading with the space filling agglomerates in a phase change alkane can provide an extremely large thermal conductivity. Though the thermal conductivity enhancement at higher particle loading was independent of the bulk thermal conductivity of dispersed nanomaterials, an anomalously large thermal contrast is observed at a very low concentration in copper nanowire suspension. These results provide new approaches to achieve large thermal storage in organic phase change materials.

  17. Effect of sugars on headgroup mobility in freeze-dried dipalmitoylphosphatidylcholine bilayers: solid-state 31P NMR and FTIR studies.

    PubMed Central

    Tsvetkova, N M; Phillips, B L; Crowe, L M; Crowe, J H; Risbud, S H

    1998-01-01

    The effect of the carbohydrates trehalose, glucose, and hydroxyethyl starch (HES) on the motional properties of the phosphate headgroup of freeze-dried dipalmitoylphosphatidylcholine (DPPC) liposomes was studied by means of 31P NMR, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The results show that trehalose, which is a strong glass former (Tg = 115 degreesC), elevates the onset of the lipid headgroup rotations and preserves some rotational mobility of the phosphate headgroups after cooling from the liquid-crystalline state. Glucose (Tg = 30 degreesC), a very effective depressant of the phase transition temperature of freeze-dried DPPC, markedly elevates the initiation of the temperature of headgroup rotations. On the other hand, the monosaccharide does not preserve the headgroup disordering when cooled from the liquid-crystalline state. These effects are consistent with formation of hydrogen bonds between the OH groups of the sugar and the polar headgroups of DPPC. They show, however, that hydrogen bonding is not sufficient for preservation of the dynamic properties of freeze-dried DPPC. HES, although a very good glass former (Tg > 110 degreesC), does not depress the phase transition temperature and affects only slightly the rotational properties of freeze-dried DPPC. This lack of effect of HES is associated with the absence of direct interactions with the lipid phosphates, as evidenced by the FTIR results. These data show that vitrification of the additive is not sufficient to affect the dynamic properties of dried DPPC. PMID:9826615

  18. Effect of sugars on headgroup mobility in freeze-dried dipalmitoylphosphatidylcholine bilayers: solid-state 31P NMR and FTIR studies.

    PubMed

    Tsvetkova, N M; Phillips, B L; Crowe, L M; Crowe, J H; Risbud, S H

    1998-12-01

    The effect of the carbohydrates trehalose, glucose, and hydroxyethyl starch (HES) on the motional properties of the phosphate headgroup of freeze-dried dipalmitoylphosphatidylcholine (DPPC) liposomes was studied by means of 31P NMR, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The results show that trehalose, which is a strong glass former (Tg = 115 degreesC), elevates the onset of the lipid headgroup rotations and preserves some rotational mobility of the phosphate headgroups after cooling from the liquid-crystalline state. Glucose (Tg = 30 degreesC), a very effective depressant of the phase transition temperature of freeze-dried DPPC, markedly elevates the initiation of the temperature of headgroup rotations. On the other hand, the monosaccharide does not preserve the headgroup disordering when cooled from the liquid-crystalline state. These effects are consistent with formation of hydrogen bonds between the OH groups of the sugar and the polar headgroups of DPPC. They show, however, that hydrogen bonding is not sufficient for preservation of the dynamic properties of freeze-dried DPPC. HES, although a very good glass former (Tg > 110 degreesC), does not depress the phase transition temperature and affects only slightly the rotational properties of freeze-dried DPPC. This lack of effect of HES is associated with the absence of direct interactions with the lipid phosphates, as evidenced by the FTIR results. These data show that vitrification of the additive is not sufficient to affect the dynamic properties of dried DPPC. PMID:9826615

  19. Metabolic changes in Avena sativa crowns recovering from freezing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recove...

  20. Prospective Primary School Teachers' Perceptions on Boiling and Freezing

    ERIC Educational Resources Information Center

    Senocak, Erdal

    2009-01-01

    The aim of this study was to investigate the perceptions of prospective primary school teachers on the physical state of water during the processes of boiling and freezing. There were three stages in the investigation: First, open-ended questions concerning the boiling and freezing of water were given to two groups of prospective primary school…

  1. Understanding freeze stress in biological tissues: thermodynamics of interfacial water

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A thermodynamic approach to distinguish forms of freeze energy that injure plants as the temperature decreases is developed. The pattern resulting from this analysis dictated the sequence of thermal requirements for water to exist as an independent state. Improvement of freezing tolerance in biolo...

  2. Observation of a freezing drizzle episode: A case study

    NASA Astrophysics Data System (ADS)

    Fernández-González, S.; Valero, F.; Sanchez, Jose L.; Gascón, E.; López, L.; García-Ortega, E.; Merino, A.

    2014-11-01

    On 5 February 2012 an episode of freezing precipitation took place in the Guadarrama Mountains, at the center of the Iberian Peninsula. This precipitation affected high elevations, where temperatures remained below freezing because of snow cover that had accumulated from snowfall during the previous days. The case study was recorded by surface synoptic observations (SYNOP) at Navacerrada Pass meteorological observatory (belonging to the National Weather Service of Spain). To study winter cloud systems during the TEcoAgua project, a multichannel ground-based microwave radiometer (MMWR), Micro Rain Radar (MRR-2), and isothermal cloud chamber were installed in the study area, thus permitting the monitoring of the freezing precipitation event. Analysis using Meteosat Second Generation (MSG) satellite data and observations permitted the determination of factors that triggered the freezing precipitation event. Freezing drizzle was interspersed with the passage of a warm and cold front. During frontal passage, mid-level clouds inhibited the generation of freezing drizzle, with snowfall recorded in the study area. However, during the period between the two fronts, an absence of mid-level clouds permitted low-level orographic clouds to persist upwind of the mountain system, producing freezing drizzle at the surface. The decisive factors for the generation of freezing drizzle were high humidity at low levels, weak mesoscale updrafts caused by the topography, stability at mid levels, cloud-top temperatures warmer than - 15 °C, and low concentrations of ice nuclei.

  3. Using infrared thermography to study freezing in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Factors that determine when and to what extent a plant will freeze are complex. While thermocouples have served as the main method of monitoring the freezing process in plants, infrared thermography offers distinct advantages, and the use of this latter technology has provided new insights on the p...

  4. Savanna Tree Seedlings are Physiologically Tolerant to Nighttime Freeze Events

    PubMed Central

    O’Keefe, Kimberly; Nippert, Jesse B.; Swemmer, Anthony M.

    2016-01-01

    Freeze events can be important disturbances in savanna ecosystems, yet the interactive effect of freezing with other environmental drivers on plant functioning is unknown. Here, we investigated physiological responses of South African tree seedlings to interactions of water availability and freezing temperatures. We grew widely distributed South African tree species (Colophospermum mopane, Combretum apiculatum, Acacia nigrescens, and Cassia abbreviata) under well-watered and water-limited conditions and exposed individuals to nighttime freeze events. Of the four species studied here, C. mopane was the most tolerant of lower water availability. However, all species were similarly tolerant to nighttime freezing and recovered within one week following the last freezing event. We also show that water limitation somewhat increased freezing tolerance in one of the species (C. mopane). Therefore, water limitation, but not freezing temperatures, may restrict the distribution of these species, although the interactions of these stressors may have species-specific impacts on plant physiology. Ultimately, we show that unique physiologies can exist among dominant species within communities and that combined stresses may play a currently unidentified role in driving the function of certain species within southern Africa. PMID:26870065

  5. Spin dynamics and freezing in magnetic rare-earth quasicrystals

    NASA Astrophysics Data System (ADS)

    Noakes, D. R.; Kalvius, G. M.; Wäppling, R.; Stronach, C. E.; White, M. F., Jr.; Saito, H.; Fukamichi, K.

    1998-02-01

    Muon spin relaxation measurements of RE 8Mg 42Zn 50 (RE = Gd, Tb) quasicrystals have revealed slower spin dynamics and more prompt spin freezing for Tb than Gd, due to “crystalline electric field” splitting in low rare-earth site symmetry. Inhomogeneous spin freezing leads to a low-temperature state with local field distribution characteristic of a concentrated disordered magnet.

  6. Optimum parameters for freeze-drying decellularized arterial scaffolds.

    PubMed

    Sheridan, William S; Duffy, Garry P; Murphy, Bruce P

    2013-12-01

    Decellularized arterial scaffolds have achieved success in advancing toward clinical use as vascular grafts. However, concerns remain regarding long-term preservation and sterilization of these scaffolds. Freeze drying offers a means of overcoming these concerns. In this study, we investigated the effects of various freeze-drying protocols on decellularized porcine carotid arteries and consequently, determined the optimum parameters to fabricate a stable, preserved scaffold with unaltered mechanical properties. Freeze drying by constant slow cooling to two final temperatures ((Tf), -10 °C and -40 °C) versus instant freezing was investigated by histological examination and mechanical testing. Slow cooling to Tf= -10 °C produced a stiffer and less distensible response than the non freeze-dried scaffolds and resulted in disruption to the collagen fibers. The mechanical response of Tf= -40 °C scaffolds demonstrated disruption to the elastin network, which was confirmed with histology. Snap freezing scaffolds in liquid nitrogen and freeze drying to Tf= -40 °C with a precooled shelf at -60 °C produced scaffolds with unaltered mechanical properties and a histology resembling non-freeze-dried scaffolds. The results of this study demonstrate the importance of optimizing the nucleation and ice crystal growth/size to ensure homogenous drying, preventing extracellular matrix disruption and subsequent inferior mechanical properties. This new manufacturing protocol creates the means for the preservation and sterilization of decellularized arterial scaffolds while simultaneously maintaining the mechanical properties of the tissue. PMID:23614758

  7. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 5 2011-01-01 2011-01-01 false Quick freeze treatment requirements. 305.7 Section 305.7 Agriculture Regulations of the Department of Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze...

  8. Design of freeze-drying processes for pharmaceuticals: practical advice.

    PubMed

    Tang, Xiaolin; Pikal, Michael J

    2004-02-01

    Design of freeze-drying processes is often approached with a "trial and error" experimental plan or, worse yet, the protocol used in the first laboratory run is adopted without further attempts at optimization. Consequently, commercial freeze-drying processes are often neither robust nor efficient. It is our thesis that design of an "optimized" freeze-drying process is not particularly difficult for most products, as long as some simple rules based on well-accepted scientific principles are followed. It is the purpose of this review to discuss the scientific foundations of the freeze-drying process design and then to consolidate these principles into a set of guidelines for rational process design and optimization. General advice is given concerning common stability issues with proteins, but unusual and difficult stability issues are beyond the scope of this review. Control of ice nucleation and crystallization during the freezing step is discussed, and the impact of freezing on the rest of the process and final product quality is reviewed. Representative freezing protocols are presented. The significance of the collapse temperature and the thermal transition, denoted Tg', are discussed, and procedures for the selection of the "target product temperature" for primary drying are presented. Furthermore, guidelines are given for selection of the optimal shelf temperature and chamber pressure settings required to achieve the target product temperature without thermal and/or mass transfer overload of the freeze dryer. Finally, guidelines and "rules" for optimization of secondary drying and representative secondary drying protocols are presented. PMID:15032301

  9. St. Lawrence River Freeze-Up Forecast Procedure.

    ERIC Educational Resources Information Center

    Assel, R. A.

    A standard operating procedure (SOP) is presented for calculating the date of freeze-up on the St. Lawrence River at Massena, N.Y. The SOP is based on two empirical temperature decline equations developed for Kingston, Ontario, and Massena, N.Y., respectively. Input data needed to forecast freeze-up consist of the forecast December flow rate and…

  10. Logistic Regression Analysis of Freezing Tolerance in Winter Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Four winter wheat cultivars, Eltan, Froid, Kestrel, and Tiber, were cold-acclimated for five weeks and then tested for freezing tolerance in a programmable freezer. The temperature of the soil was recorded every two minutes and the freezing episode was described as five parameters: the minimum temp...

  11. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 5 2012-01-01 2012-01-01 false Quick freeze treatment requirements. 305.7 Section 305.7 Agriculture Regulations of the Department of Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze...

  12. 40 CFR 52.1135 - Regulation for parking freeze.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... conform to the requirements of 40 CFR 51.4(b); and the agency rules or procedures may provide that if no... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Regulation for parking freeze. 52.1135... for parking freeze. (a) Definitions: (1) The phrase to commence construction means to engage in...

  13. 40 CFR 52.1135 - Regulation for parking freeze.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... conform to the requirements of 40 CFR 51.4(b); and the agency rules or procedures may provide that if no... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Regulation for parking freeze. 52.1135... for parking freeze. (a) Definitions: (1) The phrase to commence construction means to engage in...

  14. Savanna Tree Seedlings are Physiologically Tolerant to Nighttime Freeze Events.

    PubMed

    O'Keefe, Kimberly; Nippert, Jesse B; Swemmer, Anthony M

    2016-01-01

    Freeze events can be important disturbances in savanna ecosystems, yet the interactive effect of freezing with other environmental drivers on plant functioning is unknown. Here, we investigated physiological responses of South African tree seedlings to interactions of water availability and freezing temperatures. We grew widely distributed South African tree species (Colophospermum mopane, Combretum apiculatum, Acacia nigrescens, and Cassia abbreviata) under well-watered and water-limited conditions and exposed individuals to nighttime freeze events. Of the four species studied here, C. mopane was the most tolerant of lower water availability. However, all species were similarly tolerant to nighttime freezing and recovered within one week following the last freezing event. We also show that water limitation somewhat increased freezing tolerance in one of the species (C. mopane). Therefore, water limitation, but not freezing temperatures, may restrict the distribution of these species, although the interactions of these stressors may have species-specific impacts on plant physiology. Ultimately, we show that unique physiologies can exist among dominant species within communities and that combined stresses may play a currently unidentified role in driving the function of certain species within southern Africa. PMID:26870065

  15. 40 CFR 52.1135 - Regulation for parking freeze.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Regulation for parking freeze. 52.1135 Section 52.1135 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1135 Regulation for parking freeze. (a) Definitions:...

  16. 40 CFR 52.1135 - Regulation for parking freeze.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Regulation for parking freeze. 52.1135 Section 52.1135 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1135 Regulation for parking freeze. (a) Definitions:...

  17. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... electronic authorization should confirm appropriate verification data (e.g., the subscriber's date of birth... subscriber's date of birth or social security number) and the information required in § 64.1190(d)(3)(ii)(A... carrier administering the freeze and the subscriber in order to lift a freeze. When engaged in...

  18. Stopping biological time: The freezing of living cells

    SciTech Connect

    Mazur, P.

    1987-01-01

    The fundamental physical-chemical events that occur during the freezing and thawing of cells are outlined and the manner in which cell permeability determines the response of the cell to freezing is discussed both in terms of physical response and in terms of survival. 40 refs., 12 figs.

  19. Optimum Parameters for Freeze-Drying Decellularized Arterial Scaffolds

    PubMed Central

    Sheridan, William S.; Duffy, Garry P.

    2013-01-01

    Decellularized arterial scaffolds have achieved success in advancing toward clinical use as vascular grafts. However, concerns remain regarding long-term preservation and sterilization of these scaffolds. Freeze drying offers a means of overcoming these concerns. In this study, we investigated the effects of various freeze-drying protocols on decellularized porcine carotid arteries and consequently, determined the optimum parameters to fabricate a stable, preserved scaffold with unaltered mechanical properties. Freeze drying by constant slow cooling to two final temperatures ((Tf), −10°C and −40°C) versus instant freezing was investigated by histological examination and mechanical testing. Slow cooling to Tf= −10°C produced a stiffer and less distensible response than the non freeze-dried scaffolds and resulted in disruption to the collagen fibers. The mechanical response of Tf= −40°C scaffolds demonstrated disruption to the elastin network, which was confirmed with histology. Snap freezing scaffolds in liquid nitrogen and freeze drying to Tf= −40°C with a precooled shelf at −60°C produced scaffolds with unaltered mechanical properties and a histology resembling non-freeze-dried scaffolds. The results of this study demonstrate the importance of optimizing the nucleation and ice crystal growth/size to ensure homogenous drying, preventing extracellular matrix disruption and subsequent inferior mechanical properties. This new manufacturing protocol creates the means for the preservation and sterilization of decellularized arterial scaffolds while simultaneously maintaining the mechanical properties of the tissue. PMID:23614758

  20. STEFINS: a steel freezing integral simulation program

    SciTech Connect

    Frank, M.V.

    1980-09-01

    STEFINS (STEel Freezing INtegral Simulation) is a computer program for the calculation of the rate of solidification of molten steel on solid steel. Such computations arize when investigating core melt accidents in fast reactors. In principle this problem involves a coupled two-dimensional thermal and hydraulic approach. However, by physically reasonable assumptions a decoupled approach has been developed. The transient solidification of molten steel on a cold wall is solved in the direction normal to the molten steel flow and independent from the solution for the molten steel temperature and Nusselt number along the direction of flow. The solutions to the applicable energy equations have been programmed in cylindrical and slab geometries. Internal gamma heating of steel is included.

  1. Freezing of Martian streams under climatic conditions

    NASA Technical Reports Server (NTRS)

    Carr, M. H.

    1984-01-01

    The valley networks of Mars are widely believed to have formed at a time when climatic conditions on the planet were significantly different from those that currently prevail. This view arises from the following observations: (1) the valleys form integrated branching networks which suggests fluid drainage, and water is the most plausible fluid, (2) the present atmosphere contains only minute amounts of water, (3) the networks appear to be more akin to terrestrial valleys that are eroded by streams of modest discharges than features that form by catastrophic floods, and (4) small streams of water will rapidly freeze under present climatic conditions. Climatic conditions at the time of formation of the valleys are studied based on the assumption that they were cut by running water.

  2. Freezing D2O clay gels.

    PubMed

    Letellier, M

    1998-01-01

    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

  3. Conservation of mouse models through embryo freezing.

    PubMed

    Guan, Mo; Bogani, Debora; Marschall, Susan; Raspa, Marcello; Takeo, Toru; Nakagata, Naomi; Fray, Martin

    2014-01-01

    The ability to interrogate the entire coding sequence of the mouse combined with the tools to manipulate the genome has firmly established the mouse as the model organism of choice for studying the causes of human disease. Consequently, a huge number of novel mouse models are generated each year to support active research programs. However, it is neither ethically justifiable, nor economically viable to maintain mouse colonies on the shelf that are not part of active research programs. This means that novel mouse lines have to be preserved in some way. If this is not done and the line is simply killed off, the genetics will be lost to future generations of scientists. This article describes the current practices used in cryopreservation laboratories to archive and recover mouse embryos frozen using controlled-rate freezing and vitrification techniques. PMID:25723186

  4. Climatic variability and the evolution of insect freeze tolerance.

    PubMed

    Sinclair, Brent J; Addo-Bediako, A; Chown, Steven L

    2003-05-01

    Insects may survive subzero temperatures by two general strategies: Freeze-tolerant insects withstand the formation of internal ice, while freeze-avoiding insects die upon freezing. While it is widely recognized that these represent alternative strategies to survive low temperatures, and mechanistic understanding of the physical and molecular process of cold tolerance are becoming well elucidated, the reasons why one strategy or the other is adopted remain unclear. Freeze avoidance is clearly basal within the arthropod lineages, and it seems that freeze tolerance has evolved convergently at least six times among the insects (in the Blattaria, Orthoptera, Coleoptera, Hymenoptera, Diptera and Lepidoptera). Of the pterygote insect species whose cold-tolerance strategy has been reported in the literature, 29% (69 of 241 species studied) of those in the Northern Hemisphere, whereas 85 % (11 of 13 species) in the Southern Hemisphere exhibit freeze tolerance. A randomization test indicates that this predominance of freeze tolerance in the Southern Hemisphere is too great to be due to chance, and there is no evidence of a recent publication bias in favour of new reports of freeze-tolerant species. We conclude from this that the specific nature of cold insect habitats in the Southern Hemisphere, which are characterized by oceanic influence and climate variability must lead to strong selection in favour of freeze tolerance in this hemisphere. We envisage two main scenarios where it would prove advantageous for insects to be freeze tolerant. In the first, characteristic of cold continental habitats of the Northern Hemisphere, freeze tolerance allows insects to survive very low temperatures for long periods of time, and to avoid desiccation. These responses tend to be strongly seasonal, and insects in these habitats are only freeze tolerant for the overwintering period. By contrast, in mild and unpredictable environments, characteristic of habitats influenced by the Southern Ocean, freeze tolerance allows insects which habitually have ice nucleators in their guts to survive summer cold snaps, and to take advantage of mild winter periods without the need for extensive seasonal cold hardening. Thus, we conclude that the climates of the two hemispheres have led to the parallel evolution of freeze tolerance for very different reasons, and that this hemispheric difference is symptomatic of many wide-scale disparities in Northern and Southern ecological processes. PMID:12803420

  5. Immersion freezing of birch pollen washing water

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  6. Irrational Beliefs in Depression

    ERIC Educational Resources Information Center

    Nelson, R. Eric

    1977-01-01

    To examine the hypothesis that certain types of irrational beliefs covary with the severity of depression, 156 undergraduates completed the Beck Depression Inventory and R. G. Jone's Irrational Beliefs Test (IBT). (Author)

  7. [Depression in childhood].

    PubMed

    Messerschmitt, P

    1993-03-01

    Depressive syndromes occur at any age and require appropriate therapy. Available classifications include the French Classification of Mental Disorders in Children, the Diagnostic and Statistical Manual of Mental Disorders IIIrd edition Revised (DSM-III-R), and the International Classification of Diseases. Prevalence of depression approximates 1% to 3% in children and adults. Recent studies have investigated relationships between depression and anxiety or behavior disorders familial clustering of depression, and adult outcome of depression in children and adolescents. Early onset of major depression (before the age of 20) is an established risk factor for depression in adulthood. Pediatricians may encounter depression in emotionally deprived infants (hospitalism), victims of child abuse, and children who attempt suicide. Concepts concerning major affective disorders are changing; adolescents have specific characteristics regarding symptoms and risk of subsequent relapsing disease. Although biochemical and sleep pattern markers have not as yet been adequately studied in pediatric patients, the clinical efficacy of drug therapy has been established. PMID:8484664

  8. Depression in Children.

    ERIC Educational Resources Information Center

    Epstein, Michael H.; Cullinan, Douglas

    1986-01-01

    This article reviews research on the prevalence, classification, etiology, assessment, and treatment of childhood depression. Suggestions for school health personnel who directly or indirectly serve depressed children are given. (Author/MT)

  9. Assessment of Childhood Depression.

    ERIC Educational Resources Information Center

    Lefkowitz, Monroe M.; Tesiny, Edward P.

    1980-01-01

    Examined the psychometric properties of the Peer Nomination Inventory of Depression (PNID). Reliability proved highly acceptable. Content validity was determined by experts' judgments. Subjects with high PNID scores exhibited depressed intellectual functioning, poor social behavior, and diminished ebullience. (Author)

  10. Screening for Depression

    MedlinePlus

    ... events Visit the podcast archive Mood Disorders Depression Bipolar Disorder Anxiety Screening Center Co-occurring Illnesses/Disorders Related ... for Your Patients Information about Depression Information about Bipolar Disorder Wellness Tools DBSA Support Groups Active Research Studies ...

  11. Depression and College Students

    MedlinePlus

    ... medical illness with many symptoms, including physical ones. Sadness is only a small part of depression. Some people with depression may not feel sadness at all, but be more irritable, or just ...

  12. Postpartum Depression Facts

    MedlinePlus

    ... a free hardcopy With postpartum depression, feelings of sadness and anxiety can be extreme and might interfere ... Mothers with postpartum depression experience feelings of extreme sadness, anxiety, and exhaustion that may make it difficult ...

  13. Help With Depression

    MedlinePlus

    ... A More What is the difference between normal sadness or grieving and depression? Everyone experiences a range ... depression often welcome the ability to feel normal sadness again, to have a “bad day,” as opposed ...

  14. Postpartum Depression Action Plan

    MedlinePlus

    MENU Return to Web version Postpartum Depression | Postpartum Depression Action Plan Patient __________________________ Physician/NP/PA __________________ Clinic ____________________________ Phone Number ____________________ Choose one area and add other areas as you begin to ...

  15. Genetic biomarkers of depression

    PubMed Central

    Tamatam, Anand; Khanum, Farhath; Bawa, Amarinder Singh

    2012-01-01

    Depression is a term that has been used to describe a variety of ailments, ranging from minor to incapacitating. Clinically significant depression, termed as major depression, is a serious condition characterized not only by depressed mood but also by a cluster of somatic, cognitive, and motivational symptoms. Significant research efforts are aimed to understand the neurobiological as well as psychiatric disorders, and the evaluation of treatment of these disorders is still based solely on the assessment of symptoms. In order to identify the biological markers for depression, we have focused on gathering information on different factors responsible for depression including stress, genetic variations, neurotransmitters, and cytokines and chemokines previously suggested to be involved in the pathophysiology of depression. The present review illustrates the potential of biomarker profiling for psychiatric disorders, when conducted in large collections. The review highlighted the biomarker signatures for depression, warranting further investigation. PMID:22754217

  16. Depression and Suicide Risk

    MedlinePlus

    Depression and Suicide Risk (2014) Definition: A mood disorder that causes a persistent feeling of sadness and loss of interest. It ... mental disorders, recurrent episodes and higher rates of suicide. New Classification in the DSMV: xi • Major depressive ...

  17. Older Adults and Depression

    MedlinePlus

    ... treatment. If left untreated, depression can lead to suicide. Depression is a common problem among older adults, ... not wanting to eat at all Thoughts of suicide, suicide attempts Aches or pains, headaches, cramps, or ...

  18. Depression in the Workplace

    MedlinePlus

    ... Anxiety Infographic: Life with Depression Infographic: Life with Bipolar Infographic: Life with Psychosis Infographic: Life in Recovery ... Mental Health First Aid Mental Health Info Anxiety Bipolar Depression Post Traumatic Stress Disorder Psychosis All Other ...

  19. Depression and African Americans

    MedlinePlus

    ... Anxiety Infographic: Life with Depression Infographic: Life with Bipolar Infographic: Life with Psychosis Infographic: Life in Recovery ... Mental Health First Aid Mental Health Info Anxiety Bipolar Depression Post Traumatic Stress Disorder Psychosis All Other ...

  20. [Effect of freezing and cooking on the texture and electrophoretic pattern of the proteins of octopus arms (Octopus vulgaris)].

    PubMed

    Reyes, Genara; Nirchio, Mauro; Bello, Rafael; Borderías, Javier

    2014-09-01

    Texture is the most valuable feature in cephalopods. Factors that mainly affect the texture of octopus are: freezing, scalding and cooking. The aim of this study was to assess the effect of freezing, scalding and length of cooking time on the texture and electrophoretic pattern of proteins of octopus arms. Octopuses were trapped near Margarita Island and carried with ice to the laboratory where they were packed and subjected to: a) freezing at -27 degrees C or at -20 degrees C b) scalding c) cooking for 25 min, 35 min or 45 min. Shear force was determined by Kramer cell on strips of octopus arms. SDS-PAGE was done according to the Laemmli method with 12% polyacrilamide gels. A sensory evaluation of the preference of texture was carried out using a hedonic scale of 7-points and a non-trained panel. Octopus texture was not affected by freezing temperature or scalding. Frozen octopus was softer after cooking than fresh. The longer the cooking time was, the softer the octopus was. Myosin heavy chain (MHC) was not significantly affected by scalding or cooking; however large aggregates heavier than MHC, new bands and loss of resolution of the bands appeared. Myosin and paramyosin bands were more affected by freezing prior to cooking. PMID:26137796

  1. Versatile Aerogel Fabrication by Freezing and Subsequent Freeze-Drying of Colloidal Nanoparticle Solutions.

    PubMed

    Freytag, Axel; Sánchez-Paradinas, Sara; Naskar, Suraj; Wendt, Natalja; Colombo, Massimo; Pugliese, Giammarino; Poppe, Jan; Demirci, Cansunur; Kretschmer, Imme; Bahnemann, Detlef W; Behrens, Peter; Bigall, Nadja C

    2016-01-18

    A versatile method to fabricate self-supported aerogels of nanoparticle (NP) building blocks is presented. This approach is based on freezing colloidal NPs and subsequent freeze drying. This means that the colloidal NPs are directly transferred into dry aerogel-like monolithic superstructures without previous lyogelation as would be the case for conventional aerogel and cryogel fabrication methods. The assembly process, based on a physical concept, is highly versatile: cryogelation is applicable for noble metal, metal oxide, and semiconductor NPs, and no impact of the surface chemistry or NP shape on the resulting morphology is observed. Under optimized conditions the shape and volume of the liquid equal those of the resulting aerogels. Also, we show that thin and homogeneous films of the material can be obtained. Furthermore, the physical properties of the aerogels are discussed. PMID:26638874

  2. What happens in freezing bodies? Experimental study of histological tissue change caused by freezing injuries.

    PubMed

    Schäfer, A T; Kaufmann, J D

    1999-06-28

    In order to evaluate histological features of freezing damages to human tissue after death, we froze samples of liver and heart tissue to temperatures of -12 degrees C, -28 degrees C and -80 degrees C, and stored them for 24 and 72 h, respectively, at those temperatures. After thawing and routine preparation for histology, the samples were evaluated both by microscope and with an electronic image analyzer. In all cases, we found extended extracellular spaces and shrunken cells resulting from the freeze-thaw cycle. These features were more pronounced in tissues stored for longer durations. Such findings seem to be typical of tissue that has been frozen prior to examination. Two cases of dead bodies found outdoors at subzero temperatures demonstrate that formerly frozen and unfrozen tissues can be distinguished histologically. The findings are examined in relation to the fundamental laws of cryobiology. PMID:10464930

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

    NASA Technical Reports Server (NTRS)

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

    1950-01-01

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

  4. Freeze plug proves safe, economical in riser repair

    SciTech Connect

    Nelson, M.J.

    1995-05-01

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

  5. Sources of Data on Freezing Rain and Resulting Damages.

    NASA Astrophysics Data System (ADS)

    Changnon, Stanley A.; Creech, Tamara G.

    2003-10-01

    Freezing rain produces major damages each year in the United States, and various affected groups continue to seek data on the incidence and losses produced by freezing rain. The various kinds of data available about freezing rain and related damages have been identified and assessed as part of a project to develop long-term databases. Data include long-term records of the occurrences of freezing rain, 50-yr records of insured property losses, and measures and estimates of ice loading on wires and structures. Many years of interactions with affected and interested groups and individuals, such as the insurance industry and design engineers, led to the preparation of this summary that describes the various sources of data on freezing-rain and ice-storm damages. The benefits and limitations of each form of data are presented to help to guide potential data users.

  6. Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors

    SciTech Connect

    Gomez, A.; Villanueva, R.; Vie, D.; Murcia-Mascaros, S.; Martinez, E.; Beltran, A.; Sapina, F.; Vicent, M.; Sanchez, E.

    2013-01-15

    Nanocrystalline zirconia powders have been obtained at the multigram scale by thermal decomposition of precursors resulting from the freeze-drying of aqueous acetic solutions. This technique has equally made possible to synthesize a variety of nanostructured yttria or scandia doped zirconia compositions. SEM images, as well as the analysis of the XRD patterns, show the nanoparticulated character of those solids obtained at low temperature, with typical particle size in the 10-15 nm range when prepared at 673 K. The presence of the monoclinic, the tetragonal or both phases depends on the temperature of the thermal treatment, the doping concentration and the nature of the dopant. In addition, Rietveld refinement of the XRD profiles of selected samples allows detecting the coexistence of the tetragonal and the cubic phases for high doping concentration and high thermal treatment temperatures. Raman experiments suggest the presence of both phases also at relatively low treatment temperatures. - Graphical abstract: Zr{sub 1-x}A{sub x}O{sub 2-x/2} (A=Y, Sc; 0{<=}x{<=}0.12) solid solutions have been prepared as nanostructured powders by thermal decomposition of precursors obtained by freeze-drying, and this synthetic procedure has been scaled up to the 100 g scale. Highlights: Black-Right-Pointing-Pointer Zr{sub 1-x}A{sub x}O{sub 2-x/2} (A=Y, Sc; 0{<=}x{<=}0.12) solid solutions have been prepared as nanostructured powders. Black-Right-Pointing-Pointer The synthetic method involves the thermal decomposition of precursors obtained by freeze-drying. Black-Right-Pointing-Pointer The temperature of the thermal treatment controls particle sizes. Black-Right-Pointing-Pointer The preparation procedure has been scaled up to the 100 g scale. Black-Right-Pointing-Pointer This method is appropriate for the large-scale industrial preparation of multimetallic systems.

  7. Fabrication of porous ceramics by freeze-casting/freeze-drying. Final report, April 1991-December 1992

    SciTech Connect

    Johnson, S.M.; Gusman, M.I.

    1993-04-01

    Porous ceramics have many applications in the gas industry, including gas separation, filtration, catalyst supports and substrates, lightweight insulation, and burners. The report explores the fabrication of porous ceramics by a new approach involving the use of cryogenic processing techniques such as freeze-drying, to characterize the materials formed in this way, and to evaluate the potential of the techniques for making porous ceramics for specific gas industry applications.

  8. Method of treating depression

    SciTech Connect

    Henn, Fritz

    2012-01-24

    Methods for treatment of depression-related mood disorders in mammals, particularly humans are disclosed. The methods of the invention include administration of compounds capable of enhancing glutamate transporter activity in the brain of mammals suffering from depression. ATP-sensitive K.sup.+ channel openers and .beta.-lactam antibiotics are used to enhance glutamate transport and to treat depression-related mood disorders and depressive symptoms.

  9. Method of treating depression

    DOEpatents

    Henn, Fritz

    2013-04-09

    Methods for treatment of depression-related mood disorders in mammals, particularly humans are disclosed. The methods of the invention include administration of compounds capable of enhancing glutamate transporter activity in the brain of mammals suffering from depression. ATP-sensitive K.sup.+ channel openers and .beta.-lactam antibiotics are used to enhance glutamate transport and to treat depression-related mood disorders and depressive symptoms.

  10. Evaluation and Validation of the Messinger Freezing Fraction

    NASA Technical Reports Server (NTRS)

    Anderson, David N.; Tsao, Jen-Ching

    2005-01-01

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

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

    PubMed

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

    2014-02-18

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

  12. Childhood Depression: Developmental Considerations.

    ERIC Educational Resources Information Center

    Herzog, David B.; Rathbun, Jennifer M.

    1982-01-01

    The authors question the American Psychiatric Association position that the criteria for adult and childhood depression are the same and emphasize the developmental aspects of depressive symptoms providing diagnostic guidelines for depression at five different stages from infancy through adolescence. Journal availability: see EC 143 201.…

  13. Category Accessibility and Depression.

    ERIC Educational Resources Information Center

    McCann, C. Douglas; Gotlib, Ian H.

    Cognitive processes, particularly in regard to negative content schemata, seem to play an instrumental role in the development and maintenance of depression. In order to better understand the nature of negative schemata in depressed individuals, both depressed and nondepressed subjects participated in two studies in which they were required to

  14. Depression and Aging.

    ERIC Educational Resources Information Center

    Hamilton, Marshall, Ed.

    1982-01-01

    Contains four articles related to depression and aging. Compares normal adults with those having a major depressive disorder. Focuses on life satisfaction in the elderly, describing an individualized measure of life satisfaction. Describes similarities and differences between grief and depression. Contains a psychometric analysis of the Zung…

  15. Prevention of Depression.

    ERIC Educational Resources Information Center

    Compas, Bruce E.; Connor, Jennifer; Wadsworth, Martha

    Substantial numbers of children and adolescents experience symptoms of sadness, dysphoria, and other characteristics associated with depression. The nature of depression in children and adolescents has presented challenges in identification and definition. This chapter reviews research on depression in children and adolescents. Three current…

  16. Clinical Judgments of Depression.

    ERIC Educational Resources Information Center

    Jackson, Douglas N.; And Others

    1986-01-01

    Investigated degree to which judges could simulate Basic Personality Inventory (BPI) responses of a clinically depressed patient group. Judgmental profiles of depressed patients indicated very high reliabilities across information conditions, a high association with actual profiles of clinically depressed patients, and differentiation from other…

  17. Depression and Mental Retardation.

    ERIC Educational Resources Information Center

    O'Neil, Marie A.

    Mentally retarded people may be particularly vulnerable to depression and related emotional disturbances due to limited social skills, lack of friends, and negative self-esteem. A therapy group for depressed retarded clients provided an opportunity to collect information about depression in retarded individuals and to evaluate various treatment…

  18. Heart disease and depression

    MedlinePlus

    Heart disease and depression often go hand-in-hand. You are are more likely to feel sad or depressed after a heart attack ... heart disease. The good news is that treating depression may help improve both your mental and physical ...

  19. Clinical and molecular genetics of psychotic depression.

    PubMed

    Domschke, Katharina

    2013-07-01

    This review provides a comprehensive overview of clinical and molecular genetic as well as pharmacogenetic studies regarding the clinical phenotype of "psychotic depression." Results are discussed with regard to the long-standing debate on categorical vs dimensional disease models of affective and psychotic disorders on a continuum from unipolar depression over bipolar disorder and schizoaffective disorder to schizophrenia. Clinical genetic studies suggest a familial aggregation and a considerable heritability (39%) of psychotic depression partly shared with schizoaffective disorder, schizophrenia, and affective disorders. Molecular genetic studies point to potential risk loci of psychotic depression shared with schizoaffective disorder (1q42, 22q11, 19p13), depression, bipolar disorder, and schizophrenia (6p, 8p22, 10p13-12, 10p14, 13q13-14, 13q32, 18p, 22q11-13) and several vulnerability genes possibly contributing to an increased risk of psychotic symptoms in depression (eg, BDNF, DBH, DTNBP1, DRD2, DRD4, GSK-3beta, MAO-A). Pharmacogenetic studies implicate 5-HTT, TPH1, and DTNBP1 gene variation in the mediation of antidepressant treatment response in psychotic depression. Genetic factors are suggested to contribute to the disease risk of psychotic depression in partial overlap with disorders along the affective-psychotic spectrum. Thus, genetic research focusing on psychotic depression might inspire a more dimensional, neurobiologically and symptom-oriented taxonomy of affective and psychotic disorders challenging the dichotomous Kraepelinian view. Additionally, pharmacogenetic studies might aid in the development of a more personalized treatment of psychotic depression with an individually tailored antidepressive/antipsychotic pharmacotherapy according to genotype. PMID:23512949

  20. Investigation of the stabilizing effects of hydroxyethyl cellulose on LDH during freeze drying and freeze thawing cycles.

    PubMed

    Al-Hussein, Anas; Gieseler, Henning

    2015-01-01

    The objective of this study was to investigate both the cryoprotective and lyoprotective effects of the polymer hydroxyethyl cellulose (HEC) on the model protein lactate dehydrogenase (LDH) during freeze thawing and freeze drying cycles. The effect of annealing on both protein stability and the physical state of HEC was evaluated. HEC was used as a sole excipient in the protein formulations, and its stabilizing was compared to that of other excipients which are commonly used in freeze dried protein formulations. Furthermore, other quality aspects of the freeze dried samples containing solely HEC were investigated, such as, reconstitution time and product elegance. Protein stability was evaluated functionally by measuring the activity recovery of the model protein LDH. The physical state of HEC after freeze drying was investigated and compared to this of other studied solutes using differential scanning calorimetry and X-ray powder diffractometry. HEC showed superior cryoprotective effects on LDH during freeze thawing, and considerable lyoprotective effects during the freeze drying process. Annealing had limited influence on the stabilizing effect of HEC. The extensive reconstitution times of the HEC lyophilisates could be greatly improved by incorporation of the surfactant Tween 80 into the formulations prior to freeze drying. PMID:24286265

  1. Importance of Depression in Diabetes.

    ERIC Educational Resources Information Center

    Lustman, Patrick J.; Clouse, Ray E.; Anderson, Ryan J.

    Depression doubles the likelihood of comorbid depression, which presents as major depression in 11% and subsyndromal depression in 31% of patients with the medical illness. The course of depression is chronic, and afflicted patients suffer an average of one episode annually. Depression has unique importance in diabetes because of its association…

  2. Effects of industrial pre-freezing processing and freezing handling on glucosinolates and antioxidant attributes in broccoli florets.

    PubMed

    Cai, Congxi; Miao, Huiying; Qian, Hongmei; Yao, Leishuan; Wang, Bingliang; Wang, Qiaomei

    2016-11-01

    The effects of industrial pre-freezing processing and freezing handling on the contents of glucosinolates and antioxidants (vitamin C, polyphenols, carotenoid and chlorophyll), as well as the antioxidant capacity in broccoli (Brassica oleracea L. var. italica) florets were investigated in the present study. Our results showed that the glucosinolate accumulations were significantly decreased after pre-freezing processing, whereas elevated levels of phenols, carotenoids, chlorophyll, and also antioxidant capacity were observed in frozen broccoli florets. The contents of vitamin C remained constant during above mentioned processing. In conclusion, the current industrial freezing processing method is a good practice for the preservation of main antioxidant nutrients in broccoli florets, although some improvements in pre-freezing processing, such as steam blanching and ice-water cooling, are needed to attenuate the decrease in glucosinolate content. PMID:27211670

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

    NASA Astrophysics Data System (ADS)

    Abdelnaby, Abdelhady Abdelhakeam

    1988-12-01

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

  4. Depression in dementia

    PubMed Central

    Kitching, David

    2015-01-01

    SUMMARY People with dementia of any type have a high incidence of major depression. The occurrence of a first major depressive episode in an older adult is a risk factor for developing dementia. Management of depression in a person with dementia should be enthusiastic with an aim to optimise quality of life. Non-pharmacological and pharmacological strategies are both important in treating depression in dementia and management of these patients requires a collaborative approach. Selective serotonin reuptake inhibitors are the first-line pharmacotherapy for depression in dementia, although they are less likely to be effective in older people. PMID:26843714

  5. Clarification on Mechanical Characteristic in State of Stress of Osteoarthritis of the Hip Joint Using Stress Freezing Method

    NASA Astrophysics Data System (ADS)

    Maezaki, Nobutaka; Ezumi, Tsutomu; Hachiya, Masashi

    In this research, the Osteoarthritis of Hip Joint was pick up, the 3-dimensional stress freezing method of photoelastic method was applied, and the state of the stress in the normality hip joint and the transformable hip joint was examined. The direction and the singular point of principal stress and stress distribution were experimentally examined. At result, The Osteoarthritis of Hip Joint touches by 2 points, Osteoarthritis of Hip Joint occurrence of the new singular point with flat of the femoral head, They change the direction of the principal stress line in an existing singular point is cause.

  6. Metabolic mechanisms for anoxia tolerance and freezing survival in the intertidal gastropod, Littorina littorea.

    PubMed

    Storey, Kenneth B; Lant, Benjamin; Anozie, Obiajulu O; Storey, Janet M

    2013-08-01

    The gastropod mollusk, Littorina littorea L., is a common inhabitant of the intertidal zone along rocky coastlines of the north Atlantic. This species has well-developed anoxia tolerance and freeze tolerance and is extensively used as a model for exploring the biochemical adaptations that support these tolerances as well as for toxicological studies aimed at identifying effective biomarkers of aquatic pollution. This article highlights our current understanding of the molecular mechanisms involved in anaerobiosis and freezing survival of periwinkles, particularly with respect to anoxia-induced metabolic rate depression. Analysis of foot muscle and hepatopancreas metabolism includes anoxia-responsive changes in enzyme regulation, signal transduction, gene expression, post-transcriptional regulation of mRNA, control of translation, and cytoprotective strategies including chaperones and antioxidant defenses. New studies describe the regulation of glucose-6-phosphate dehydrogenase by reversible protein phosphorylation, the role of microRNAs in suppressing mRNA translation in the hypometabolic state, modulation of glutathione S-transferase isozyme patterns, and the regulation of the unfolded protein response. PMID:23507570

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

    PubMed

    Knopf, Daniel A; Alpert, Peter A

    2013-01-01

    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

  8. Depression during pregnancy

    PubMed Central

    Ryan, Deirdre; Milis, Lisa; Misri, Nicholas

    2005-01-01

    OBJECTIVE To review existing literature on depression during pregnancy and to provide information for family physicians in order to promote early detection and treatment. QUALITY OF EVIDENCE MEDLINE was searched from January 1989 through August 2004 using the key words depression, pregnancy, prenatal, and antenatal. Articles focusing on depression during pregnancy were chosen for review; these articles were based on expert opinion (level III evidence) and prospective studies (level II evidence). MAIN MESSAGE Pregnancy does not safeguard women against depressive illness. The Edinburgh Postnatal Depression Scale is an effective screening tool for identifying women with depressive symptoms during pregnancy. Once diagnosed with major depression, these patients need to be monitored closely for up to a year after delivery. Patients with mild-to-moderate illness should be referred for psychotherapy. More severely ill patients might require additional treatment with antidepressants. The most commonly used antidepressants are selective serotonin reuptake inhibitors and the serotonin and norepinephrine reuptake inhibitor, venlafaxine. For each patient, risk of treatment with an antidepressant needs to be compared with risk of not treating her depressive illness. CONCLUSION Early detection of depression during pregnancy is critical because depression can adversely affect birth outcomes and neonatal health and, if left untreated, can persist after the birth. Untreated postpartum depression can impair mother-infant attachments and have cognitive, emotional, and behavioural consequences for children. PMID:16121830

  9. Immersion freezing on mineral dust particles

    NASA Astrophysics Data System (ADS)

    Zolles, Tobias; Grothe, Hinrich; Pummer, Bernhard

    2013-04-01

    Mineral dust is considered to play a major role in ice cloud nucleation in the troposphere. More than 1.000 Tg of mineral dust are aerosolized from the ground every year, 1-10% of these reach the upper troposphere [1]. At an altitude of about 8 km ice residual particle analysis has shown that about 50% of all ice nuclei (IN) are mineral dust[2]. In principle, natural occurring dusts may either be IN-active themselves or are carriers of organic and/or biological IN. Up to now the ice nucleation, i.e. cloud glaciation, has not been quantized. However, different authors report a high IN-activity for many mineral dust samples, although a systematic comparison between different minerals is still missing. Therefore, we studied selected mineral dust samples which were characterized by X-ray diffraction, FTIR spectroscopy, and scanning electron microscopy before use. Oil immersion measurements were performed on the most common minerals, clay materials and volcanic ash. The median freezing temperatures range from -21°C up to homogenous freezing at 38°C. Even though quite a few dust samples show a reasonable high IN-activity, their median freezing temperatures are low compared to biological samples [3, 4]. Furthermore, heat treatment of the dusts was applied in order to decompose and to denaturize organic and/or biological surfactants. Finally, some dust samples had a high loss of activity and thus were subjects of further experiments. These mineral dust particles were suspended in water and after an incubation time were removed. In some cases the washing water had become IN-active, but lost its activity after enzymatic treatment. The observed high IN-activity can thus be explained by adsorbed biological materials. The results suggest that some mineral dusts are IN-active, and if it is not intrinsic they may even enhance IN-activity of organic and biological IN if these are adsorbed on the dust particle surface. A relatively high IN-activity of the pure mineral dusts was only observed in quartz, clays, and mixed natural dusts (ATD), which are mainly composed of SiO2 and clays. References. [1] C. S. Zender, R. L. Miller and I. Tegen, Eos Trans. AGU, 2004,85, 509. [2] K. A. Pratt, P. J. DeMott, J. R. French, Z. Wang, D. L. Westphal, A. J. Heymsfield, C. H. Twohy, A. J. Prenni, K. A. Prather, Nat. Geosci., 2009, 2, 397-400. [3] B. Pummer, H. Bauer, J. Bernardi, S. Bleicher and H. Grothe, Atmos. Chem. Phys., 2012, 12, 2541-2550. [4] V. T. J. Phillips, C. Andronache, B. Christner, C. E. Morris, D. C. Sands, A. Bansemer, A. Lauer, C. McNaughton and C. Seman, Biogeosciences, 2009, 6, 987-1014.

  10. Freeze-Thaw Durability of Air-Entrained Concrete

    PubMed Central

    Shang, Huai-Shuai; Yi, Ting-Hua

    2013-01-01

    One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results. PMID:23576906

  11. Freeze-Thaw Days in the Northeastern United States.

    NASA Astrophysics Data System (ADS)

    Schmidlin, Thomas W.; Dethier, Bernard E.; Eggleston, Keith L.

    1987-01-01

    A freeze-thaw day is defined as a weather observation day with a maximum temperature of 0°C or above and a minimum temperature of 2.2°C or below recorded in an instrument shelter 1.5 m above the ground. The 30 winter during 1950-80 are examined at 228 stations in nine northeastern states. Average annual freeze-thaw days range from over 90 at high elevations in the north to less than 50 along the Long Island and New Jersey shores and in the Philadelphia area. Freeze-thaw days are most common during midwinter months in the south but peak in March across inland sections. Freeze-thaw days are most numerous with average monthly temperatures between 2°C and 0°C and approach zero at monthly temperatures below 13°C and above 11°C.The number of freeze-thaw days with less than 7.5 cm of snow cover is about 95% of the total number along the southern coasts and less than 50% of the total in northern snowy climates. The air at 15 cm height experiences 13% more freeze-thaw days than the air at 150 cm, due to a larger daily temperature range. Hilltops experience fewer freeze-thaw days than valley bottoms.

  12. Freeze-thaw durability of air-entrained concrete.

    PubMed

    Shang, Huai-Shuai; Yi, Ting-Hua

    2013-01-01

    One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results. PMID:23576906

  13. Water Relations of Pachysandra Leaves during Freezing and Thawing 1

    PubMed Central

    Zhu, Jian-Jun; Beck, Erwin

    1991-01-01

    The evergreen herb Pachysandra terminalis becomes moderately frost-hardy in winter. The water relations of its frost-hardy leaves were studied during a freeze-thaw cycle. Leaf water potentials, measured by psychrometry at subfreezing temperatures, were identical with those of ice, indicating equilibrium freezing. Microscopic observations showed extracellular freezing of tissue water. As evidenced by thermal analysis, the freezing process starts with the crystallization of a minor volume which was identified as apoplasmic water. The following long-lasting exotherm indicated slow export of water from the protoplasts driven by extracellular crystallization. In partially frozen leaves, the fractions of liquid water were measured at several subfreezing temperatures by nuclear magnetic resonance spectroscopy. They were consistently greater than those calculated from the osmotic potentials of cellular fluid, and the differences increased with decreasing temperature. About 50% of the differences could be abolished by freeze-killing of the leaf and was thus ascribed to the effect of a (negative) pressure reinforcing the osmotic potential. The persistent part of the differences may have reflected a matric component. At ?7C, the absolute values of both potentials were ?1.7 megapascals each. The water relations of Pachysandra leaves clearly indicate nonideal equilibrium freezing where negative pressures and matric potentials contribute to the leaf water potential and thus alleviate freeze-dehydration of the tissue. ImagesFigure 1Figure 5 PMID:16668501

  14. Metabolic Changes in Avena sativa Crowns Recovering from Freezing

    PubMed Central

    Henson, Cynthia A.; Duke, Stanley H.; Livingston, David P.

    2014-01-01

    Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L.) during a fourteen day time-course after freezing. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after freezing. In contrast, sugar and sugar related metabolites were little changed by freezing, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after freezing were similar to those observed in cold acclimation whereas most changes in sugar pools after freezing were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants. PMID:24675792

  15. HIV infection and depression.

    PubMed

    Arseniou, Stylianos; Arvaniti, Aikaterini; Samakouri, Maria

    2014-02-01

    Major depression is highly prevalent among HIV-positive patients (HIVpp). The prevalence of depression ranges between 18% and 81%, depending on the population studied and the methodology of the study. The etiology of depression in HIVpp is likely determined by: (i) biological factors (alterations in the white matter structure, hypothalamic-pituitary-thyroid dysfunction, Tat-protein-induced depressive behavior); (ii) psychosocial factors (HIV stigma, occupational disability, body image changes, isolation and debilitation); (iii) history or comorbidity of psychiatric illness; and (iv) the perinatal period in HIVpp women. Symptomatology of depression differs between HIVpp and HIV-negative patients (HIVnp). Depression may also alter the function of lymphocytes in HIVpp and decrease natural killer cell activity, contributing to the increased mortality in these patients. Selective serotonin re-uptake inhibitors are considered the first-line treatment. Treatment of depression can improve quality of life and lead to a better prognosis of HIV infection. PMID:24552630

  16. Depression in adolescence

    PubMed Central

    Thapar, Anita; Collishaw, Stephan; Pine, Daniel S; Thapar, Ajay K

    2012-01-01

    Unipolar depressive disorder in adolescence is common worldwide but often unrecognised. The incidence, notably in girls, rises sharply after puberty and, by the end of adolescence, the 1 year prevalence rate exceeds 4%. The burden is highest in low-income and middle-income countries. Depression is associated with sub stantial present and future morbidity, and heightens suicide risk. The strongest risk factors for depression in adolescents are a family history of depression and exposure to psychosocial stress. Inherited risks, developmental factors, sex hormones, and psychosocial adversity interact to increase risk through hormonal factors and associated perturbed neural pathways. Although many similarities between depression in adolescence and depression in adulthood exist, in adolescents the use of antidepressants is of concern and opinions about clinical management are divided. Effective treatments are available, but choices are dependent on depression severity and available resources. Prevention strategies targeted at high-risk groups are promising. PMID:22305766

  17. Basic concepts of depression

    PubMed Central

    Paykel, Eugene S.

    2008-01-01

    This paper reviews concepts of depression, including history and classification. The original broad concept of melancholia included all forms of quiet insanity. The term depression began to appear in the nineteenth century as did the modern concept of affective disorders, with the core disturbance now viewed as one of mood. The 1930s saw the introduction of defined criteria into official diagnostic schemes. The modern separation into unipolar and bipolar disorder was introduced following empirical research by Angst and Perris in the 1960s. The partially overlapping distinctions between psychotic and neurotic depression, and between endogenous and reactive depression, started to generate debate in the 1920s, with considerable multivariate research in the 1960s. The symptom element in endogenous depression currently survives in melancholia or somatic syndrome. Life stress is common in various depressive pictures. Dysthymia, a valuable diagnosis, represents a form of what was regarded earlier as neurotic depression. Other subtypes are also discussed. PMID:18979941

  18. Reading problems and depressed mood.

    PubMed

    Maughan, Barbara; Rowe, Richard; Loeber, Rolf; Stouthamer-Loeber, Magda

    2003-04-01

    Although reading difficulties show well-established overlaps with disruptive behavior disorders in childhood, much less is known about reading-disabled children's vulnerability to emotional difficulties. Using longitudinal data from 6 assessments of boys in the Pittsburgh Youth Study, we found robust links between severe, persistent reading problems and increased risk for depressed mood in a community sample of boys aged 7 and 10 years at initial assessment, though not in those who had already entered their teens. These associations could not be accounted for in terms of selected family risks or comorbid disruptive behaviors; instead, the pattern of the findings pointed to the existence of more direct causal processes whereby reading problems influence younger boys' risk of depressed mood. PMID:12735404

  19. Spatiotemporal measurement of freezing-induced deformation of engineered tissues

    PubMed Central

    Teo, Ka Yaw; Dutton, J. Craig; Han, Bumsoo

    2010-01-01

    In order to cryopreserve functional engineered tissues (ETs), the microstructure of the extracellular matrix (ECM) should be maintained as well as the cellular viability since the functionality is closely related to the ECM microstructure. Since the post-thaw ECM microstructure is determined by the deformation of ETs during cryopreservation, freezing-induced deformation of ETs was measured with a newly developed quantum dot (QD)-mediated cell image deformetry system using dermal equivalents as a model tissue. The dermal equivalents were constructed by seeding QD-labeled fibroblasts in type I collagen matrices. After 24 hour incubation, the ETs were directionally frozen by exposing them to a spatial temperature gradient (from 4 °C to −20 °C over a distance of 6 mm). While being frozen, the ETs were consecutively imaged, and consecutive pairs of these images were two-dimensionally cross-correlated to determine the local deformation during freezing. The results showed that freezing induced the deformation of ET, and its magnitude varied with both time and location. The maximum local dilatation was 0.006 s−1 and was always observed at the phase change interface. Due to this local expansion, the unfrozen region in front of the freezing interface experienced compression. This expansion-compression pattern was observed throughout the freezing process. In the unfrozen region, the deformation rate gradually decreased away from the freezing interface. After freezing/thawing, the ET experienced an approximately 28% decrease in thickness and 8% loss in weight. These results indicate that freezing-induced deformation caused the transport of interstitial fluid and the interstitial fluid was extruded. In summary, the results suggest that complex cell-fluid-matrix interactions occur within ETs during freezing, and these interactions determine the post-thaw ECM microstructure and eventual post-thaw tissue functionality. PMID:20459191

  20. Air-Cooled Stack Freeze Tolerance Freeze Failure Modes and Freeze Tolerance Strategies for GenDriveTM Material Handling Application Systems and Stacks Final Scientific Report

    SciTech Connect

    Hancock, David, W.

    2012-02-14

    Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below freezing, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was freeze tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology for air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve freeze tolerance and mitigate freeze-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. Freeze tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack freeze tolerance. At this time, the most cost effective solutions are at the system level. The freeze mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.

  1. Definition of Hydrologic Response Units in Depression Plagued Digital Elevation Models

    NASA Astrophysics Data System (ADS)

    Lindsay, J. B.; Creed, I. F.

    2002-12-01

    Definition of hydrologic response units using digital elevation models (DEMs) is sensitive to the occurrence of topographic depressions. Real depressions can be important to the hydrology and biogeochemistry a catchment, often coinciding with areas of surface saturation. Artifact depressions, in contrast, result in digital "black holes", artificially truncating the hydrologic flow lengths and altering hydrologic flow directions, parameters that are often used in defining hydrologic response units. Artifact depressions must be removed from DEMs prior to definition of hydrologic response units. Depression filling or depression trenching techniques can be used to remove these artifacts. Depression trenching methods are often considered more appropriate because they preserve the topographic variability within a depression thus avoiding the creation of spurious flat areas. Current trenching algorithms are relatively slow and unable to process very large or noisy DEMs. A new trenching algorithm that overcomes these limitations is described. The algorithm does not require finding depression catchments or outlets, nor does it need special handling for nested depressions. Therefore, artifacts can be removed from large or noisy DEMs efficiently, while minimizing the number of grid elevations requiring modification. The resulting trench is a monotonically descending path starting from the lowest point in a depression, passing through the depression's outlet, and ending at a point of lower elevation outside the depression. The importance of removing artifact depressions is demonstrated by showing hydrologic response units both before and after the removal of artifact depressions from the DEM.

  2. Freeze Tape Casting of Functionally Graded Porous Ceramics

    NASA Technical Reports Server (NTRS)

    Sofie, Stephen W.

    2007-01-01

    Freeze tape casting is a means of making preforms of ceramic sheets that, upon subsequent completion of fabrication processing, can have anisotropic and/or functionally graded properties that notably include aligned and graded porosity. Freeze tape casting was developed to enable optimization of the microstructures of porous ceramic components for use as solid oxide electrodes in fuel cells: Through alignment and grading of pores, one can tailor surface areas and diffusion channels for flows of gas and liquid species involved in fuel-cell reactions. Freeze tape casting offers similar benefits for fabrication of optimally porous ceramics for use as catalysts, gas sensors, and filters.

  3. Freezing-induced deformation of biomaterials in cryomedicine

    NASA Astrophysics Data System (ADS)

    Ozcelikkale, Altug

    Cryomedicine utilizes low temperature treatments of biological proteins, cells and tissues for cryopreservation, materials processing and cryotherapy. Lack of proper understanding of cryodamage that occurs during these applications remains to be the primary bottleneck for development of successful tissue cryopreservation and cryosurgery procedures. An engineering approach based on a view of biological systems as functional biomaterials can help identify, predict and control the primary cryodamage mechanisms by developing an understanding of underlying freezing-induced biophysical processes. In particular, freezing constitutes the main structural/mechanical origin of cryodamage and results in significant deformation of biomaterials at multiple length scales. Understanding of these freezing-induced deformation processes and their effects on post-thaw biomaterial functionality is currently lacking but will be critical to engineer improved cryomedicine procedures. This dissertation addresses this problem by presenting three separate but related studies of freezing-induced deformation at multiple length scales including nanometer-scale protein fibrils, single cells and whole tissues. A combination of rigorous experimentation and computational modeling is used to characterize post-thaw biomaterial structure and properties, predict biomaterial behavior and assess its post-thaw biological functionality. Firstly, freezing-induced damage on hierarchical extracellular matrix structure of collagen is investigated at molecular, fibril and matrix levels. Results indicate to a specific kind of fibril damage due to freezing-induced expansion of intrafibrillar fluid. This is followed by a study of freezing-induced cell and tissue deformation coupled to osmotically driven cellular water transport. Computational and semi empirical modeling of these processes indicate that intracellular deformation of the cell during freezing is heterogeneous and can interfere with cellular water transport, thereby leading to previously unconsidered mechanisms of cell freezing response. In addition, cellular water transport is identified as the critical limiting factor on the amount of freezing-induced tissue deformation, particularly in native tissues with high cell densities. Finally, effects of cryopreservation on post-thaw biological functionality of collagen engineered tissue constructs is investigated where cell-matrix interactions during fibroblast migration are considered as the functional response. Simultaneous cell migration and extracellular matrix deformation are characterized. Results show diminished cell-matrix coupling by freeze/thaw accompanied by a subtle decrease in cell migration. A connection between these results and freezing-induced collagen fibril damage is also suggested. Overall, this dissertation provides new fundamental knowledge on cryodamage mechanisms and a collection of novel multi-purpose engineering tools that will open the way for rational design of cryomedicine technologies.

  4. Delayed freezing of water droplet on silver nanocolumnar thin film

    NASA Astrophysics Data System (ADS)

    Singh, Dhruv P.; Singh, Jitendra P.

    2013-06-01

    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.

  5. Marital Processes around Depression: A Gendered and Relational Perspective

    PubMed Central

    Thomeer, Mieke Beth; Umberson, Debra; Pudrovska, Tetyanna

    2015-01-01

    Despite extensive evidence of the importance of marriage and marital processes for mental health, little is known about the interpersonal processes around depression within marriage and the extent to which these processes are gendered. We use a mixed methods approach to explore the importance of gender in shaping processes around depression within marriage; we approach this in two ways. First, using quantitative longitudinal analysis of 2,601 couples from the Health and Retirement Study (HRS), we address whether depressive symptoms in one spouse shape the other spouse's depressive symptoms and whether men or women are more influential in this process. We find that a wife's depressive symptoms influence her husband's future depressive symptoms but a husband's depressive symptoms do not influence his wife's future symptoms. Second, we conduct a qualitative analysis of in-depth interviews with 29 couples wherein one or both spouses experienced depression to provide additional insight into how gender impacts depression and reactions to depression within marriage. Our study points to the importance of cultural scripts of masculinity and femininity in shaping depression and emotional processes within marriage and highlights the importance of applying a gendered couple-level approach to better understand the mental health effects of marital processes. PMID:25914855

  6. Size control in production and freeze-drying of poly-ε-caprolactone nanoparticles.

    PubMed

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

    2014-06-01

    This work is focused on the control of poly-ε-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. PMID:24737658

  7. Combining confocal Raman microscopy and freeze-drying for quantification of substance penetration into human skin.

    PubMed

    Franzen, Lutz; Anderski, Juliane; Planz, Viktoria; Kostka, Karl-Heinz; Windbergs, Maike

    2014-12-01

    In the area of dermatological research, the knowledge of rate and extent of substance penetration into the human skin is essential not only for evaluation of therapeutics, but also for risk assessment of chemicals and cosmetic ingredients. Recently, confocal Raman microscopy emerged as a novel analytical technique for analysis of substance skin penetration. In contrast to destructive drug extraction and quantification, the technique is non-destructive and provides high spatial resolution in three dimensions. However, the generation of time-resolved concentration depth profiles is restrained by ongoing diffusion of the penetrating substance during analysis. To prevent that, substance diffusion in excised human skin can instantly be stopped at defined time points by freeze-drying the sample. Thus, combining sample preparation by freeze-drying with drug quantification by confocal Raman microscopy yields a novel analytical platform for non-invasive and quantitative in vitro analysis of substance skin penetration. This work presents the first proof-of-concept study for non-invasive quantitative substance depth profiling in freeze-dried excised human stratum corneum by confocal Raman microscopy. PMID:25219950

  8. Amplitude Manipulation Evokes Upper Limb Freezing during Handwriting in Patients with Parkinson’s Disease with Freezing of Gait

    PubMed Central

    Heremans, Elke; Nackaerts, Evelien; Vervoort, Griet; Vercruysse, Sarah; Broeder, Sanne; Strouwen, Carolien; Swinnen, Stephan P.; Nieuwboer, Alice

    2015-01-01

    Background Recent studies show that besides freezing of gait (FOG), many people with Parkinson’s disease (PD) also suffer from freezing in the upper limbs (FOUL). Up to now, it is unclear which task constraints provoke and explain upper limb freezing. Objective To investigate whether upper limb freezing and other kinematic abnormalities during writing are provoked by (i) gradual changes in amplitude or by (ii) sustained amplitude generation in patients with and without freezing of gait. Methods Thirty-four patients with PD, including 17 with and 17 without FOG, performed a writing task on a touch-sensitive writing tablet requiring writing at constant small and large size as well as writing at gradually increasing and decreasing size. Patients of both groups were matched for disease severity, tested while ‘on’ medication and compared to healthy age-matched controls. Results Fifty upper limb freezing episodes were detected in 10 patients, including 8 with and 2 without FOG. The majority of the episodes occurred when participants had to write at small or gradually decreasing size. The occurrence of FOUL and the number of FOUL episodes per patient significantly correlated with the occurrence and severity of FOG. Patients with FOUL also showed a significantly smaller amplitude in the writing parts outside the freezing episodes. Conclusions Corroborating findings of gait research, the current study supports a core problem in amplitude control underlying FOUL, both in maintaining as well as in flexibly adapting the cycle size. PMID:26580556

  9. Comparison of the depth of tissue necrosis between double-freeze and single-freeze nitrous oxide-based cryotherapy

    PubMed Central

    Adepiti, Akinfolarin Clement; Ajenifuja, Olusegun Kayode; Fadahunsi, Oluwaseyi Olatunji; Osasan, Stephen Adebayo; Pelemo, Olumuyiwa Eyitayo; Loto, Morebishe Olabisi

    2016-01-01

    Background: Cryotherapy is one the methods of treating cervical premalignant lesions. It is particularly suitable for low-resource countries because of it is relative cheaper, has low cost of maintenance, ease of use and that does not require electricity which is in short supply in many rural areas of developing countries where the incidence and mortality from cervical cancer is very high. In this study we compared single and double freezing on the cervices of women admitted for hysterectomy for benign conditions using Nitrous-based cryotherapy. Materials and Methods: Patients admitted for elective hysterectomy for benign gynaecological conditions were randomized into two arms. The first group had single freeze cryotherapy while the second arm received double freeze cryotherapy. The cervices were examined 24 hours later to determine the depth of tissue necrosis. Results: In this comparative study, the depth of tissue necrosis was deeper with double freeze compared with single freeze. Also in both arms, the depth of necrosis was deeper on anterior lips than on posterior lips of the cervix. Conclusion: Double freeze technique achieve more depth of tissue necrosis than single-freeze on both anterior and posterior lips of the cervix. PMID:27185971

  10. Red blood cell preservation by droplet freezing with polyvinyl pyrrolidone or sucrose/dextrose and by bulk freezing with glycerol

    PubMed Central

    Schmid, Pirmin; Huvard, Michael J.; Lee-Stroka, A. Hallie; Lee, Jae Y.; Byrne, Karen M.; Flegel, Willy A.

    2012-01-01

    Background Red blood cell (RBC) preservation is essential to transfusion medicine. Many blood group reference laboratories need a method to preserve rare blood samples for serologic testing at a later date. This study offers a comparison of three common cryoprotective agents and protocols used today: bulk preservation with glycerol and droplet freezing with sucrose/dextrose (S+D) or polyvinyl pyrrolidone (PVP). Study design and methods Human blood from 14 volunteers was collected and frozen at set intervals over two weeks with PVP, S+D, or glycerol. The frozen RBCs were later thawed and the percentage of surviving RBCs was determined. Detailed protocols and an instructional video are supplied. Results Over a two week period, RBCs preserved with glycerol and thawed with a widely used protocol showed a recovery of 41 ± 16 % (mean ± standard deviation) while those thawed with a modified glycerol protocol showed a recovery of 76 ± 8 %. RBCs preserved by droplet freezing with S+D showed a recovery of 56 ± 11 % while those preserved by droplet freezing with PVP showed a recovery of 85 ± 6 %. Recovery values were similar with ethylenediaminetetraacetic acid (EDTA) or heparin anticoagulants, differing freezing rates, and varying droplet volumes. Conclusion Droplet freezing with PVP offered the greatest recovery. While bulk freezing with glycerol can be effective too, droplet freezing may be a more convenient method overall. It requires less effort to thaw, needs much less storage room, and allows blood group laboratories to be frugal with thawing rare samples. PMID:21790629

  11. Freezing water in no-man's land.

    PubMed

    Manka, Alexandra; Pathak, Harshad; Tanimura, Shinobu; Wölk, Judith; Strey, Reinhard; Wyslouzil, Barbara E

    2012-04-01

    We report homogeneous ice nucleation rates between 202 K and 215 K, thereby reducing the measurement gap that previously existed between 203 K and 228 K. These temperatures are significantly below the homogenous freezing limit, T(H)≈ 235 K for bulk water, and well within no-man's land. The ice nucleation rates are determined by characterizing nanodroplets with radii between 3.2 and 5.8 nm produced in a supersonic nozzle using three techniques: (1) pressure trace measurements to determine the properties of the flow as well as the temperature and velocity of the droplets, (2) small angle X-ray scattering (SAXS) to measure the size and number density of the droplets, and (3) Fourier Transform Infrared (FTIR) spectroscopy to follow the liquid to solid phase transition. Assuming that nucleation occurs throughout the droplet volume, the measured ice nucleation rates J(ice,V) are on the order of 10(23) cm(-3) s(-1), and agree well with published values near 203 K. PMID:22354018

  12. Satellite freeze forecast system: Executive summary

    NASA Technical Reports Server (NTRS)

    Martsolf, J. D. (Principal Investigator)

    1983-01-01

    A satellite-based temperature monitoring and prediction system consisting of a computer controlled acquisition, processing, and display system and the ten automated weather stations called by that computer was developed and transferred to the national weather service. This satellite freeze forecasting system (SFFS) acquires satellite data from either one of two sources, surface data from 10 sites, displays the observed data in the form of color-coded thermal maps and in tables of automated weather station temperatures, computes predicted thermal maps when requested and displays such maps either automatically or manually, archives the data acquired, and makes comparisons with historical data. Except for the last function, SFFS handles these tasks in a highly automated fashion if the user so directs. The predicted thermal maps are the result of two models, one a physical energy budget of the soil and atmosphere interface and the other a statistical relationship between the sites at which the physical model predicts temperatures and each of the pixels of the satellite thermal map.

  13. Adaptation to seasonality and the winter freeze.

    PubMed

    Preston, Jill C; Sandve, Simen R

    2013-01-01

    Flowering plants initially diversified during the Mesozoic era at least 140 million years ago in regions of the world where temperate seasonal environments were not encountered. Since then several cooling events resulted in the contraction of warm and wet environments and the establishment of novel temperate zones in both hemispheres. In response, less than half of modern angiosperm families have members that evolved specific adaptations to cold seasonal climates, including cold acclimation, freezing tolerance, endodormancy, and vernalization responsiveness. Despite compelling evidence for multiple independent origins, the level of genetic constraint on the evolution of adaptations to seasonal cold is not well understood. However, the recent increase in molecular genetic studies examining the response of model and crop species to seasonal cold offers new insight into the evolutionary lability of these traits. This insight has major implications for our understanding of complex trait evolution, and the potential role of local adaptation in response to past and future climate change. In this review, we discuss the biochemical, morphological, and developmental basis of adaptations to seasonal cold, and synthesize recent literature on the genetic basis of these traits in a phylogenomic context. We find evidence for multiple genetic links between distinct physiological responses to cold, possibly reinforcing the coordinated expression of these traits. Furthermore, repeated recruitment of the same or similar ancestral pathways suggests that land plants might be somewhat pre-adapted to dealing with temperature stress, perhaps making inducible cold traits relatively easy to evolve. PMID:23761798

  14. Estimating collision efficiencies from contact freezing experiments

    NASA Astrophysics Data System (ADS)

    Nagare, B.; Marcolli, C.; Stetzer, O.; Lohmann, U.

    2015-04-01

    Interactions of atmospheric aerosols with clouds influence cloud properties and modify the aerosol life cycle. Aerosol particles act as cloud condensation nuclei and ice nucleating particles or become incorporated into cloud droplets by scavenging. For an accurate description of aerosol scavenging and ice nucleation in contact mode, collision efficiency between droplets and aerosol particles needs to be known. This study derives the collision rate from experimental contact freezing data obtained with the ETH Collision Ice Nucleation Chamber CLINCH. Freely falling 80 μm water droplets are exposed to an aerosol consisting of 200 nm diameter silver iodide particles of concentrations from 500-5000 cm-3, which act as ice nucleating particles in contact mode. The chamber is kept at ice saturation in the temperature range from 236-261 K leading to slow evaporation of water droplets giving rise to thermophoresis and diffusiophoresis. Droplets and particles bear charges inducing electrophoresis. The experimentally derived collision efficiency of 0.13 is around one order of magnitude higher than theoretical formulations which include Brownian diffusion, impaction, interception, thermophoretic, diffusiophoretic and electric forces. This discrepancy is most probably due to uncertainties and inaccuracies in the description of thermophoretic and diffusiophoretic processes acting together. This is to the authors knowledge the first dataset of collision efficiencies acquired below 273 K. More such experiments with different droplet and particle diameters are needed to improve our understanding of collision processes acting together.

  15. Stochastic flux freezing and magnetic dynamo.

    PubMed

    Eyink, Gregory L

    2011-05-01

    Magnetic flux conservation in turbulent plasmas at high magnetic Reynolds numbers is argued neither to hold in the conventional sense nor to be entirely broken, but instead to be valid in a statistical sense associated to the "spontaneous stochasticity" of Lagrangian particle trajectories. The latter phenomenon is due to the explosive separation of particles undergoing turbulent Richardson diffusion, which leads to a breakdown of Laplacian determinism for classical dynamics. Empirical evidence is presented for spontaneous stochasticity, including numerical results. A Lagrangian path-integral approach is then exploited to establish stochastic flux freezing for resistive hydromagnetic equations and to argue, based on the properties of Richardson diffusion, that flux conservation must remain stochastic at infinite magnetic Reynolds number. An important application of these results is the kinematic, fluctuation dynamo in nonhelical, incompressible turbulence at magnetic Prandtl number (Pr(m)) equal to unity. Numerical results on the Lagrangian dynamo mechanisms by a stochastic particle method demonstrate a strong similarity between the Pr(m)=1 and 0 dynamos. Stochasticity of field-line motion is an essential ingredient of both. Finally, some consequences for nonlinear magnetohydrodynamic turbulence, dynamo, and reconnection are briefly considered. PMID:21728673

  16. Adaptation to seasonality and the winter freeze

    PubMed Central

    Preston, Jill C.; Sandve, Simen R.

    2013-01-01

    Flowering plants initially diversified during the Mesozoic era at least 140 million years ago in regions of the world where temperate seasonal environments were not encountered. Since then several cooling events resulted in the contraction of warm and wet environments and the establishment of novel temperate zones in both hemispheres. In response, less than half of modern angiosperm families have members that evolved specific adaptations to cold seasonal climates, including cold acclimation, freezing tolerance, endodormancy, and vernalization responsiveness. Despite compelling evidence for multiple independent origins, the level of genetic constraint on the evolution of adaptations to seasonal cold is not well understood. However, the recent increase in molecular genetic studies examining the response of model and crop species to seasonal cold offers new insight into the evolutionary lability of these traits. This insight has major implications for our understanding of complex trait evolution, and the potential role of local adaptation in response to past and future climate change. In this review, we discuss the biochemical, morphological, and developmental basis of adaptations to seasonal cold, and synthesize recent literature on the genetic basis of these traits in a phylogenomic context. We find evidence for multiple genetic links between distinct physiological responses to cold, possibly reinforcing the coordinated expression of these traits. Furthermore, repeated recruitment of the same or similar ancestral pathways suggests that land plants might be somewhat pre-adapted to dealing with temperature stress, perhaps making inducible cold traits relatively easy to evolve. PMID:23761798

  17. Stochastic flux freezing and magnetic dynamo

    SciTech Connect

    Eyink, Gregory L.

    2011-05-15

    Magnetic flux conservation in turbulent plasmas at high magnetic Reynolds numbers is argued neither to hold in the conventional sense nor to be entirely broken, but instead to be valid in a statistical sense associated to the ''spontaneous stochasticity'' of Lagrangian particle trajectories. The latter phenomenon is due to the explosive separation of particles undergoing turbulent Richardson diffusion, which leads to a breakdown of Laplacian determinism for classical dynamics. Empirical evidence is presented for spontaneous stochasticity, including numerical results. A Lagrangian path-integral approach is then exploited to establish stochastic flux freezing for resistive hydromagnetic equations and to argue, based on the properties of Richardson diffusion, that flux conservation must remain stochastic at infinite magnetic Reynolds number. An important application of these results is the kinematic, fluctuation dynamo in nonhelical, incompressible turbulence at magnetic Prandtl number (Pr{sub m}) equal to unity. Numerical results on the Lagrangian dynamo mechanisms by a stochastic particle method demonstrate a strong similarity between the Pr{sub m}=1 and 0 dynamos. Stochasticity of field-line motion is an essential ingredient of both. Finally, some consequences for nonlinear magnetohydrodynamic turbulence, dynamo, and reconnection are briefly considered.

  18. Effect of geometrical frustration on inverse freezing

    NASA Astrophysics Data System (ADS)

    Schmidt, M.; Morais, C. V.; Zimmer, F. M.

    2016-01-01

    The interplay between geometrical frustration (GF) and inverse freezing (IF) is studied within a cluster approach. The model considers first-neighbor (J1) and second-neighbor (J2) intracluster antiferromagnetic interactions between Ising spins on a checkerboard lattice and long-range disordered couplings (J ) among clusters. We obtain phase diagrams of temperature versus J1/J in two cases: the absence of J2 interaction and the isotropic limit J2=J1 , where GF takes place. An IF reentrant transition from the spin-glass (SG) to paramagnetic (PM) phase is found for a certain range of J1/J in both cases. The J1 interaction leads to a SG state with high entropy at the same time that can introduce a low-entropy PM phase. In addition, it is observed that the cluster size plays an important role. The GF increases the PM phase entropy, but larger clusters can give an entropic advantage for the SG phase that favors IF. Therefore, our results suggest that disordered systems with antiferromagnetic clusters can exhibit an IF transition even in the presence of GF.

  19. Drying a tuberculosis vaccine without freezing.

    PubMed

    Wong, Yun-Ling; Sampson, Samantha; Germishuizen, Willem Andreas; Goonesekera, Sunali; Caponetti, Giovanni; Sadoff, Jerry; Bloom, Barry R; Edwards, David

    2007-02-20

    With the increasing incidence of tuberculosis and drug resistant disease in developing countries due to HIV/AIDS, there is a need for vaccines that are more effective than the present bacillus Calmette-Guérin (BCG) vaccine. We demonstrate that BCG vaccine can be dried without traditional freezing and maintained with remarkable refrigerated and room-temperature stability for months through spray drying. Studies with a model Mycobacterium (Mycobacterium smegmatis) revealed that by removing salts and cryoprotectant (e.g., glycerol) from bacterial suspensions, the significant osmotic pressures that are normally produced on bacterial membranes through droplet drying can be reduced sufficiently to minimize loss of viability on drying by up to 2 orders of magnitude. By placing the bacteria in a matrix of leucine, high-yield, free-flowing, "vial-fillable" powders of bacteria (including M. smegmatis and M. bovis BCG) can be produced. These powders show relatively minor losses of activity after maintenance at 4 degrees C and 25 degrees C up to and beyond 4 months. Comparisons with lyophilized material prepared both with the same formulation and with a commercial formulation reveal that the spray-dried BCG has better overall viability on drying. PMID:17299039

  20. Depression associated with dementia.

    PubMed

    Gutzmann, H; Qazi, A

    2015-06-01

    Depression and cognitive disorders, including dementia and mild cognitive impairment, are common disorders in old age. Depression is frequent in dementia, causing distress, reducing the quality of life, exacerbating cognitive and functional impairment and increasing caregiver stress. Even mild levels of depression can significantly add to the functional impairment of dementia patients and the severity of psychopathological and neurological impairments increases with increasing severity of depression. Depressive symptoms may be both a risk factor for, as well as a prodrome of dementia. Major depressive syndrome of Alzheimer's disease may be among the most common mood disorders of older adults. Treating depression is therefore a key clinical priority to improve the quality of life both of people with dementia as well as their carergivers. Nonpharmacological approaches and watchful waiting should be attempted first in patients who present with mild to moderate depression and dementia. In cases of severe depression or depression not able to be managed through nonpharmacological means, antidepressant therapy should be considered. PMID:25962363

  1. The depressive situation

    PubMed Central

    A. Jacobs, Kerrin

    2013-01-01

    From a naturalistic perspective on mental illness, depression is often described in terms of biological dysfunctions, while a normative perspective emphasizes the lived experience of depression as a harmful condition. The paper relates a conceptual analysis of “depressive situation” to an analysis of the lived experience of depression. As such, it predominantly aims to specify depression as a harmful condition in lights of normative perspective on mental disorder, but partially refers to empirical research, i.e., naturalistic perspective on depression, to exemplarily stress on the methodological merits and limits of relating phenomenological considerations closer to empirical research. The depressive situation is further specified with an examination of the evaluative dynamics by which individuals meaningfully relate to themselves, others and the world. These evaluative dynamics emerge out of the interplay of pre-reflective and reflective processes, which are significantly altered in depression. Such alterations of the evaluative structure are inextricably intertwined with significant distortions of practical sense in depression. From a phenomenological perspective, these distortions of practical sense show in characteristic experiences of evaluative incoherence and impairments of agency. Finally, this paper focuses on an examination of “evaluative incapacity,” which has the integrative potential to capture a range of typical changes of meaningful relatedness that determine the depressive situation. PMID:23882238

  2. Tipping Points

    NASA Astrophysics Data System (ADS)

    Hansen, J.

    2007-12-01

    A climate tipping point, at least as I have used the phrase, refers to a situation in which a changing climate forcing has reached a point such that little additional forcing (or global temperature change) is needed to cause large, relatively rapid, climate change. Present examples include potential loss of all Arctic sea ice and instability of the West Antarctic and Greenland ice sheets. Tipping points are characterized by ready feedbacks that amplify the effect of forcings. The notion that these may be runaway feedbacks is a misconception. However, present "unrealized" global warming, due to the climate system's thermal inertia, exacerbates the difficulty of avoiding global warming tipping points. I argue that prompt efforts to slow CO2 emissions and absolutely reduce non-CO2 forcings are both essential if we are to avoid tipping points that would be disastrous for humanity and creation, the planet as civilization knows it.

  3. Improvement of parameters of freezing medium and freezing protocol for bull sperm using two osmotic supports.

    PubMed

    Chaveiro, A; Machado, L; Frijters, A; Engel, B; Woelders, H

    2006-06-01

    The aim of this study was to improve the freezing protocol of bull sperm, by investigating the influence on sperm viability after freeze/thawing of different freezing medium components, as well as the effect of cooling rates in the different stages of the cooling protocol, in single factor experiments. The experimental variables were: (1) salt-based versus a sugar-based medium (Tris versus sucrose); (2) glycerol concentration; (3) detergent (Equex) concentration; (4) presence of bicarbonate; (5) rate of cooling from 22 degrees C to holding temperature (CR1); (6) holding temperature (HT); (7) rate of cooling from holding temperature to -6 degrees C (CR2); (8) rate of cooling from -10 to -100 degrees C (CR3). All experiments were performed using five bulls per experiment (three ejaculates per bull). Sperm motility after freezing and thawing was assessed by CASA system, and sperm membrane integrity was assessed by flow cytometry. Sucrose-based medium did not offer a clear significant benefit compared to Tris medium. The concentration of Equex that gave the best results in Tris-based media group and sucrose-based media group was in a range between 2-7 and 4-7 g/l, respectively. In both media groups, a glycerol concentration of 800 mM was the best in any post-thaw viability parameters. In the Tris media group, the presence of bicarbonate had a negative effect on sperm viability. CR1 and CR2 had no significant effect on any of the post-thaw sperm viability parameters, but a CR1=0.2 degrees C/min and CR2=4 degrees C/min appeared to give better results in both media. The holding temperature (HT) that gave the best results was found to be in the range of 5-9 degrees C. There was a significant disadvantage of using a low CR3 of 10 degrees C/min, while 150 degrees C/min appeared to be the best cooling rate for either medium. PMID:16310842

  4. An approximation for homogeneous freezing temperature of water droplets

    NASA Astrophysics Data System (ADS)

    O, K.-T.; Wood, R.

    2015-11-01

    In this work, based on the well-known formulae of classical nucleation theory (CNT), the temperature TNc = 1 at which the mean number of critical embryos inside a droplet is unity is derived and proposed as a new approximation for homogeneous freezing temperature of water droplets. Without consideration of time dependence and stochastic nature of the ice nucleation process, the approximation TNc = 1 is able to reproduce the dependence of homogeneous freezing temperature on drop size and water activity of aqueous drops observed in a wide range of experimental studies. We use the TNc = 1 approximation to argue that the distribution of homogeneous freezing temperatures observed in the experiments may largely be explained by the spread in the size distribution of droplets used in the particular experiment. It thus appears that this approximation is useful for predicting homogeneous freezing temperatures of water droplets in the atmosphere.

  5. 19. FIRST FLOOR LEVEL BELOW ICE FREEZING TANKS AND LOWER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. FIRST FLOOR LEVEL BELOW ICE FREEZING TANKS AND LOWER LEVEL OF ICE DUMP AND LIFT WHERE FROZEN ICE IS BROUGHT INTO STORAGE. - Atlantic Ice & Coal Company, 135 Prince Street, Montgomery, Montgomery County, AL

  6. Challenging endeavour for preservation of freeze-dried mammalian spermatozoa.

    PubMed

    Hochi, Shinichi; Abdalla, Hany; Hara, Hiromasa; Hirabayashi, Masumi

    2011-10-01

    Freeze-drying (lyophilization) has been proposed as an alternative method for sperm preservation to overcome the disadvantages of the current cryopreservation method such as the high maintenance cost of frozen stocks, the problems associated with transportation of frozen materials and the potential risk of total loss of the frozen stock. Since freeze-dried spermatozoa after rehydration lose their motility, which is an essential requirement to complete physiological fertilization, a relatively difficult microinsemination technique must be applied to rehydrated spermatozoa. Theoretically, it has been supposed that freeze-dried spermatozoa could maintain their functions and abilities to interact with the oocyte cytoplasm after prolonged storage at refrigerator temperature. However, sufficient yield of transferable blastocysts and production of live offspring derived from freeze-dried sperm samples are still subjects to be challenged and overcome in large domestic species. PMID:22052044

  7. Atmospheric science: Sea-spray particles cause freezing in clouds

    NASA Astrophysics Data System (ADS)

    Russell, Lynn M.

    2015-09-01

    Ice clouds in marine regions at high latitudes might form in warmer and drier air than was previously believed because of freezing induced by airborne particles that contain organic materials from ocean surface waters. See Letter p.234

  8. Supercooling in overwintering azalea flower buds: additional freezing parameters.

    PubMed

    George, M F; Burke, M J

    1977-02-01

    Results of calorimetric, nuclear magnetic resonance, and low temperature light microscopic studies on supercooled azalea (Rhododendron kosterianum, Schneid.) floral primordia are reported. Heat release during freezing of the supercooled floral primordia is in the range predicted for supercooled pure water. Spin-lattice and spin-spin relaxation times measured by pulsed nuclear magnetic resonance spectroscopy decreased after freezing, suggesting that a redistribution of tissue water is associated with injury to the floral primordium. The calorimetric and low temperature microscopy studies showed no detectable ice formation in floral primordia until the major freezing event at low temperature. No resistance to ice growth is found to exist in the primordium tissues, indicating that a freezing barrier or thermodynamic equilibrium exists between the unfrozen primordium and other flower bud parts which contain ice at subfreezing temperatures. PMID:16659842

  9. ARCTIC FOUNDATIONS, INC. FREEZE BARRIER SYSTEM - SITE TECHNOLOGY CAPSULE

    EPA Science Inventory

    Arctic Foundations, Inc. (AFI), of Anchorage, Alaska has developed a freeze barrier technology designed to prevent the migration of contaminants in groundwater by completely isolating contaminant source areas until appropriate remediation techniques can be applied. With this tec...

  10. ARCTIC FOUNDATIONS, INC. FREEZE BARRIER TECHNOLOGY; INNOVATIVE TECHNOLOGY EVALUATION REPORT

    EPA Science Inventory

    Arctic Foundations, Inc. (AFI), of Anchorage, Alaska has developed a freeze barrier technology designed to prevent the migration of contaminants in groundwater by completely isolating contaminant source areas until appropriate remediation techniques can be applied. With this tech...

  11. Normal freezing of ideal ternary systems of the pseudobinary type

    NASA Technical Reports Server (NTRS)

    Li, C. H.

    1972-01-01

    Perfect liquid mixing but no solid diffusion is assumed in normal freezing. In addition, the molar compositions of the freezing solid and remaining liquid, respectively, follow the solidus and liquidus curves of the constitutional diagram. For the linear case, in which both the liquidus and solidus are perfectly straight lines, the normal freezing equation giving the fraction solidified at each melt temperature and the solute concentration profile in the frozen solid was determined as early as 1902, and has since been repeatedly published. Corresponding equations for quadratic, cubic or higher-degree liquidus and solidus lines have also been obtained. The equation of normal freezing for ideal ternary liquid solutions solidified into ideal solid solutions of the pseudobinary type is given. Sample computations with the use of this new equation were made and are given for the Ga-Al-As system.

  12. Condensation and freezing of droplets on superhydrophobic surfaces.

    PubMed

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

    2014-08-01

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

  13. 7 CFR 929.11 - To can, freeze, or dehydrate.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... AGREEMENTS AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE CRANBERRIES GROWN IN STATES OF... dehydrate. To can, freeze, or dehydrate means to convert cranberries into canned, frozen, or dehydrated cranberries or other cranberry products by any commercial process....

  14. 7 CFR 929.11 - To can, freeze, or dehydrate.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE CRANBERRIES GROWN IN STATES OF... dehydrate. To can, freeze, or dehydrate means to convert cranberries into canned, frozen, or dehydrated cranberries or other cranberry products by any commercial process....

  15. 7 CFR 929.11 - To can, freeze, or dehydrate.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE CRANBERRIES GROWN IN STATES OF... dehydrate. To can, freeze, or dehydrate means to convert cranberries into canned, frozen, or dehydrated cranberries or other cranberry products by any commercial process....

  16. 7 CFR 929.11 - To can, freeze, or dehydrate.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE CRANBERRIES GROWN IN STATES OF... dehydrate. To can, freeze, or dehydrate means to convert cranberries into canned, frozen, or dehydrated cranberries or other cranberry products by any commercial process....

  17. 7 CFR 929.11 - To can, freeze, or dehydrate.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... AGREEMENTS AND ORDERS; FRUITS, VEGETABLES, NUTS), DEPARTMENT OF AGRICULTURE CRANBERRIES GROWN IN STATES OF... dehydrate. To can, freeze, or dehydrate means to convert cranberries into canned, frozen, or dehydrated cranberries or other cranberry products by any commercial process....

  18. Multiphoton imaging of biological samples during freezing and heating

    NASA Astrophysics Data System (ADS)

    Breunig, H. G.; Uchugonova, A.; König, K.

    2014-02-01

    We applied multiphoton microscopic imaging to observe freezing and heating effects in plant- and animal cell samples. The experimental setups consisted of a multiphoton imaging system and a heating and cooling stage which allows for precise temperature control from liquid nitrogen temperature (-196°C 77 K) up to +600°C (873 K) with heating/freezing rates between 0.01 K/min and 150 K/min. Two multiphoton imaging systems were used: a system based on a modified optical microscope and a flexible mobile system. To illustrate the imaging capabilities, plant leafs as well as animal cells were microscopically imaged in vivo during freezing based on autofluorescence lifetime and intensity of intrinsic molecules. The measurements illustrate the usefulness of multiphoton imaging to investigate freezing effects on animal and plant cells.

  19. Fuel Cells Vehicle Systems Analysis (Fuel Cell Freeze Investigation)

    SciTech Connect

    Pesaran, A.; Kim, G.; Markel, T.; Wipke, K.

    2005-05-01

    Presentation on Fuel Cells Vehicle Systems Analysis (Fuel Cell Freeze Investigation) for the 2005 Hydrogen, Fuel Cells & Infrastructure Technologies Program Annual Review held in Arlington, Virginia on May 23-26, 2005.

  20. [Freezing of gait is a symptom of Parkinson disease].

    PubMed

    Mezzarobba, Susanna; Bandel, Dora; Capus, Livio; Torre, Paola; Moretti, Rita

    2004-09-01

    One could distinguish between "off freezing", which is a symptom tightly bound to L-dopa dosage and titration, and is clinically bound to wearing off, and, on the contrary, "on freezing" which does not respond to therapy modifications or to different drug's titration. On freezing seems to be related to frontal-basal ganglia-pontine neural pathway disruption. This neural disruption may be related with altered perception of extra and peri-personal space which are two major problems of these patients. We demonstrate in a group of patients with "on freezing" evident defect of attention, focus capability, of set-shifting properties, and of alteration in body/space relationship. We discuss on results obtained by specific training of physiotherapy with an review on literature. PMID:15473380