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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. Depression of soil moisture freezing point

    SciTech Connect

    Fedorov, V.I.

    1996-12-01

    Certain criteria for freezing temperature of clay soil have been found which are a relative moisture content at the soil liquid limit (W/W{sub L}) and maximum hydroscopic moisture (W/W{sub h}). On the strength of test data it has been established that the relative moisture content at the soil liquid limit (W/W{sub L}) may also serve as a criterion on compression pressure and resistance against shearing for soil paste with no structural binding. Linear correlation between the moisture content of natural soil and its paste -- the equation of moisture balance -- has been found which specifies a thermodynamic balance condition. The equation of moisture balance represents a whole set of properties for a certain type of soil, such as strength and compressibility. In this respect, it may be considered as a ``Soil equation`` which allows for further prognosis of its properties.

  5. 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.

  6. Freezing point depression in model Lennard-Jones solutions

    NASA Astrophysics Data System (ADS)

    Koschke, Konstantin; Jörg Limbach, Hans; Kremer, Kurt; Donadio, Davide

    2015-09-01

    Crystallisation of liquid solutions is of uttermost importance in a wide variety of processes in materials, atmospheric and food science. Depending on the type and concentration of solutes the freezing point shifts, thus allowing control on the thermodynamics of complex fluids. Here we investigate the basic principles of solute-induced freezing point depression by computing the melting temperature of a Lennard-Jones fluid with low concentrations of solutes, by means of equilibrium molecular dynamics simulations. The effect of solvophilic and weakly solvophobic solutes at low concentrations is analysed, scanning systematically the size and the concentration. We identify the range of parameters that produce deviations from the linear dependence of the freezing point on the molal concentration of solutes, expected for ideal solutions. Our simulations allow us also to link the shifts in coexistence temperature to the microscopic structure of the solutions.

  7. 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…

  8. The freezing point depression of mammalian tissues after sudden heating in boiling distilled water.

    PubMed

    APPELBOOM, J W; BRODSKY, W A; TUTTLE, W S; DIAMOND, I

    1958-07-20

    The calculated freezing point depression of freshly excised boiled mammalian tissue is approximately the same as that of plasma. The boiling procedure was chosen to eliminate the influence of metabolism on the level of the freezing point depression. Problems created by the boiling, such as equilibrium between tissue and diluent, change in activity coefficient by dilution, and loss of CO(2) content, are discussed. A frozen crushed tissue homogenate is hypertonic to plasma. Boiling and dilution of such hypertonic homogenate exposed to room temperature for 5 to 15 minutes did not produce significant or unexplicable decreases in its osmotic activity. Moreover, freezing and crushing of a boiled diluted tissue did not produce any increase of the isoosmotic level of freezing point depression. It is possible to explain these data either with the hypothesis of hypertonic cell fluid or with that of isotonic cell fluid. In the case of an assumed isotonic cell fluid, data can be explained with one assumption, experimentally backed. In the case of an assumed hypertonic theory data can be explained only with the help of at least three ad hoc postulates. The data support the validity of the classical concept which holds that cell fluid is isotonic to extracellular fluid.

  9. 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.

  10. Measurement of freezing point depression of water in glass capillaries and the associated ice front shape.

    PubMed

    Liu, Zhihong; Muldrew, Ken; Wan, Richard G; Elliott, Janet A W

    2003-06-01

    Variations of the Kelvin equation [W. Thomson, Philos. Mag. 42, 448 (1871)] to describe the freezing point depression of water in capillaries exist in the literature. The differing equations, coupled with the uncertainty in input parameters, lead to various predictions. The difference between the predictions may become substantial when the capillary size decreases much below micron dimensions. An experiment was designed to investigate the predicted values using a customized directional solidification stage. The capillary freezing point depression for glass tubes with radii of 87 microm-3 microm was successfully measured. The image of the ice-water interface at equilibrium was also digitally captured and analyzed to examine the contact angle and the interface shape as well. Both are important for examining the hemispherical interface assumption that was exclusively used in the theoretical derivations. Finally, an equilibrium analysis of the thermodynamic system leads to a theoretical discussion of the problem. The effect of the temperature gradient on the interface shape is addressed, and an engineering criterion for the critical temperature gradient above which the effect must be considered for the interface shape calculation is derived.

  11. 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.

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  15. Theoretical and experimental studies on freezing point depression and vapor pressure deficit as methods to measure osmotic pressure of aqueous polyethylene glycol and bovine serum albumin solutions.

    PubMed

    Kiyosawa, Keitaro

    2003-05-01

    For survival in adverse environments where there is drought, high salt concentration or low temperature, some plants seem to be able to synthesize biochemical compounds, including proteins, in response to changes in water activity or osmotic pressure. Measurement of the water activity or osmotic pressure of simple aqueous solutions has been based on freezing point depression or vapor pressure deficit. Measurement of the osmotic pressure of plants under water stress has been mainly based on vapor pressure deficit. However, differences have been noted for osmotic pressure values of aqueous polyethylene glycol (PEG) solutions measured by freezing point depression and vapor pressure deficit. For this paper, the physicochemical basis of freezing point depression and vapor pressure deficit were first examined theoretically and then, the osmotic pressure of aqueous ethylene glycol and of PEG solutions were measured by both freezing point depression and vapor pressure deficit in comparison with other aqueous solutions such as NaCl, KCl, CaCl(2), glucose, sucrose, raffinose, and bovine serum albumin (BSA) solutions. The results showed that: (1) freezing point depression and vapor pressure deficit share theoretically the same physicochemical basis; (2) theoretically, they are proportional to the molal concentration of the aqueous solutions to be measured; (3) in practice, the osmotic pressure levels of aqueous NaCl, KCl, CaCl(2), glucose, sucrose, and raffinose solutions increase in proportion to their molal concentrations and there is little inconsistency between those measured by freezing point depression and vapor pressure deficit; (4) the osmotic pressure levels of aqueous ethylene glycol and PEG solutions measured by freezing point depression differed from the values measured by vapor pressure deficit; (5) the osmotic pressure of aqueous BSA solution measured by freezing point depression differed slightly from that measured by vapor pressure deficit.

  16. Revised equation and table for determining the freezing point depression of H[sub 2]O-NaCl solutions

    SciTech Connect

    Bodnar, R.J. )

    1993-02-01

    Salinities of H[sub 2]O-salt inclusions are most often determined by measuring the melting temperature of ice in the inclusion and then referring this value to an equation or table describing the relationship between salinity and freezing-point depression. Generally, data for the system H[sub 2]O-NaCl are used to determine an NaCl-equivalent salinity, owing to lack of information concerning the salts (or other electrolytes) actually contributing to the freezing-point depression. The equation most often used to determine the salinity of H[sub 2]O-salt inclusions from freezing measurements is that of Potter et al (1978), which is based on a regression of data available in the literature at that time. More recently, Hall et al (1988) experimentally redetermined the ice-melting temperatures of H[sub 2]O-NaCl-KCl solutions having compositions ranging from pure water to the ternary eutectic and to each of the two binary (H[sub 2]O-NaCl and H[sub 2]O-KCl) eutectics.

  17. The nature of aqueous solutions: insights into multiple facets of chemistry and biochemistry from freezing-point depressions.

    PubMed

    Zavitsas, Andreas A

    2010-05-25

    Contrary to current widely held beliefs, many concentrated aqueous solutions of electrolytes and nonelectrolytes behave ideally. For both, the same simple equation yields mole fractions of water that are equal to the theoretical activities of water. No empirical activity coefficients or ad hoc parameters are needed. Thermodynamic hydration numbers and the number of particles produced per mole of solute are found by searching freezing-point depression measurements, as if asking the water, "How much available water solvent is left and how many solute particles are there?" The results answer questions currently under debate: Do solutes alter the nature of water outside their immediate surroundings? What is the number of ion pairs formed by various electrolytes and what affects extents of their formation? What are some factors that cause precipitation of proteins, latexes, and so forth from aqueous solutions upon addition of other solutes (Hofmeister series)? Which nonelectrolytes form aggregates in water and what are the implications? Why do different solutes affect viscosity differently? How do ion-selective channels in cell membranes function at the molecular level? PMID:20397243

  18. The nature of aqueous solutions: insights into multiple facets of chemistry and biochemistry from freezing-point depressions.

    PubMed

    Zavitsas, Andreas A

    2010-05-25

    Contrary to current widely held beliefs, many concentrated aqueous solutions of electrolytes and nonelectrolytes behave ideally. For both, the same simple equation yields mole fractions of water that are equal to the theoretical activities of water. No empirical activity coefficients or ad hoc parameters are needed. Thermodynamic hydration numbers and the number of particles produced per mole of solute are found by searching freezing-point depression measurements, as if asking the water, "How much available water solvent is left and how many solute particles are there?" The results answer questions currently under debate: Do solutes alter the nature of water outside their immediate surroundings? What is the number of ion pairs formed by various electrolytes and what affects extents of their formation? What are some factors that cause precipitation of proteins, latexes, and so forth from aqueous solutions upon addition of other solutes (Hofmeister series)? Which nonelectrolytes form aggregates in water and what are the implications? Why do different solutes affect viscosity differently? How do ion-selective channels in cell membranes function at the molecular level?

  19. 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.

  20. 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.

  1. Monitoring the Freezing Point of Buffalo Milk

    PubMed Central

    Salzano, Caterina; De Felice, Anna; Garofalo, Francesca; Liguori, Salvatore; De Santo, Annunziata; Palermo, Pierpaolo; Guarino, Achille

    2016-01-01

    The aim of this study was to evaluate the basic freezing point of buffalo milk. Bulk milk samples were collected from buffalo and cattle farms in Caserta area from 2008 to 2014. The analysis involved a total of 1886 buffalo milk samples and 1711 bovine milk samples. These were also tested for fat, protein and lactose contents by means of infrared spectrometry. The freezing point was determined by means of a thermistor cryoscope. Data underwent statistical analysis. Our research showed an average freezing point of -0.528°C for buffalo milk and -0.522°C for bovine milk. Given the lack of data on the freezing point of buffalo milk, our study provides the first indication of a basic freezing point of the milk of this species in Italy. PMID:27800448

  2. 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).

  3. 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,…

  4. Nanomaterials for efficiently lowering the freezing point of anti-freeze coolants.

    PubMed

    Hong, Haiping; Zheng, Yingsong; 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% anti-freeze 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. PMID:18019146

  5. 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.

  6. 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.

  7. Open Zinc Freezing-Point Cell Assembly and Evaluation

    NASA Astrophysics Data System (ADS)

    Žužek, V.; Batagelj, V.; Drnovšek, J.; Bojkovski, J.

    2014-07-01

    An open metal freezing-point cell design has been developed in the Laboratory of Metrology and Quality. According to our design, a zinc cell was successfully assembled. The paper presents the needed parts for the cell, the cleaning process, and sealing of the cell. The assembled cell was then evaluated by comparison with two commercial closed zinc cells of different manufacturers. The freezing plateaus of the cells were measured, and a direct cell comparison was made. It was shown that the assembled open cell performed better than the used closed cell and was close to the brand new closed cell. The nominal purity of the zinc used for the open cell was 7 N, but the freezing plateau measurement suggests a higher impurity concentration. It was assumed that the zinc was contaminated to some extent during the process of cutting as its original shape was an irregular cylinder. The uncertainty due to impurities for the assembled cell is estimated to be 0.3 mK. Furthermore, the immersion profile and the pressure coefficient were measured. Both results are close to their theoretical values.

  8. Freezing resistance in some Antarctic fishes.

    PubMed

    DeVries, A L; Wohlschlag, D E

    1969-03-01

    Measurements of serum freezing points in three Antarctic marine fishes indicated that they do not freeze in the -1.87 degrees C seawater because their blood is isosmotic to seawater. Concentrations of sodium chloride, urea, and free amino acids in the serum accounted for only half of the freezing-point depression of the serum. A protein containing carbohydrate was isolated which accounted for 30 percent of the freezing-point depression of the serum. PMID:5764871

  9. 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.

  10. 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.

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

    SciTech Connect

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

    2013-09-11

    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.

  12. 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.

  13. 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

  14. [Depressive pseudodementia. Differential diagnosis or meeting point?].

    PubMed

    Richly, Pablo; Abdulhamid, Pablo; Bustin, Julián

    2012-01-01

    Depressive pseudodementia is a major depressive disorder in which the cognitive deficits secondary to the affective disorder is so significant that clinicians are obliged to consider dementia as a differential diagnosis. The relationship between depression and dementia is complex and intricate. Even after depressive pseudodementia has remitted, certain cognitive deficits may persist and the risk of developing dementia increases. The concept of depressive pseudodementia continues to be useful in clinical practice in spite of its limitations.

  15. Understanding and Analyzing Freezing-Point Transitions of Confined Fluids within Nanopores.

    PubMed

    Shimizu, Steven; Agrawal, Kumar Varoon; O'Mahony, Marcus; Drahushuk, Lee W; Manohar, Neha; Myerson, Allan S; Strano, Michael S

    2015-09-22

    Understanding phase transitions of fluids confined within nanopores is important for a wide variety of technological applications. It is well known that fluids confined in nanopores typically demonstrate freezing-point depressions, ΔTf, described by the Gibbs-Thomson (GT) equation. Herein, we highlight and correct several thermodynamic inconsistencies in the conventional use of the GT equation, including the fact that the enthalpy of melting, ΔHm, and the solid-liquid surface energy, γ(SL), are functions of pore diameter, complicating their prediction. We propose a theoretical analysis that employs the Turnbull coefficient, originally derived from metal nucleation theory, and show its consistency as a more reliable quantity for the prediction of ΔTf. This analysis provides a straightforward method to estimate ΔTf of nanoconfined organic fluids. As an example, we apply this technique to ibuprofen, an active pharmaceutical ingredient (API), and show that this theory fits well to the experimental ΔTf of nanoconfined ibuprofen.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    PubMed

    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. PMID:26203042

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

    PubMed

    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.

  3. 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.

  4. 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

  5. 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.

  6. Point-prevalence of depression and associated risk factors.

    PubMed

    Richards, Derek; Sanabria, Alicia Salamanca

    2014-01-01

    The study aimed to assess levels of depressive symptoms and associated risk factors in a sample of students in Bogotá, Colombia. A convenient sample (N = 254) of students at the University Antonio Nariño, Bogotá was invited to complete an online survey that contained questions associated with common risk factors for depression and the Beck Depression Inventory (BDI-II). Chi-square was used to analyze comparisons between demographic and risk factors and severity of depression, and comparisons between those depressed and not depressed. Odds Ratios and their 95% confidence interval (95% CI) were computed through logistic regression model developed for each independent variable. The point-prevalence of current depressive symptoms was 36.2%; women 47.3% and men 21.3%. Risk factors associated with depression included being a woman, having a previous diagnosis, suicidal ideation and (or) intent, sleep problems, a recent loss, and a history of family depression and alcoholism. The study confirms the high incidence of depression and associated risk factors in students. The results demonstrate a need for prevention measures, early detection and early intervention. PMID:24839729

  7. 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

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

    PubMed

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

    2012-05-01

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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  11. 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.

  12. 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.

  13. Computational fluid dynamics simulations of jet fuel flow near the freeze point temperature

    NASA Astrophysics Data System (ADS)

    Assudani, Rajee

    2006-12-01

    Under low-temperature environmental conditions, the cooling of aircraft fuel results in reduced fluidity with the potential for freezing. Therefore, it is important to study the flow and heat transfer phenomena that occur in an aircraft fuel tank near the freeze point temperature of jet fuels. The purpose of this dissertation is to study the effects of low temperatures on the flow, heat transfer and freezing of commercial and military jet fuels. The research is accomplished with the help of computational models of a thermal simulator tank and a quartz duct. Experimental results with the thermal simulator tank show that fuel flowability and pumpability decrease substantially as temperature is reduced. Time-dependent temperature and velocity distributions were numerically simulated for static cooling. Measured properties were used in all the computational fluid dynamics simulations. The calculations show that stringers, ribs, and other structures strongly promote fuel cooling. Also, the cooler, denser fuel resides near the bottom surface of the fuel tank simulator. The presence of an ullage space within the tank was found to strongly influence the fuel temperature profile by sometimes reducing cooling from the upper surface. Moreover, since the presence of ullage space is an explosion risk, some military aircraft fuel tanks are fitted with explosion suppressant polyurethane foam. To study the effect of foam on the flowability and heat transfer inside the simulator tank, the wing tank thermal simulator was filled with military specified polyurethane foam. The tank was simultaneously drained and cooled and the mass flow rate results showed that flowability of the fuel is not affected by the presence of foam. However, the presence of foam certainly affected the heat transfer phenomenon inside the fuel tank when the simulator tank was cooled and drained simultaneously. To study the freezing behavior of jet fuel under forced flow conditions, a quartz duct was fabricated

  14. 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

  15. 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.

  16. Fast membrane osmometer as alternative to freezing point and vapor pressure osmometry.

    PubMed

    Grattoni, Alessandro; Canavese, Giancarlo; Montevecchi, Franco Maria; Ferrari, Mauro

    2008-04-01

    Osmometry is an essential technique for solution analysis and the investigation of chemical and biological phenomena. Commercially available osmometers rely on the measurements of freezing point, vapor pressure, and osmotic pressure of solutions. Although vapor pressure osmometry (VPO) and freezing point osmometry (FPO) can perform rapid and inexpensive measurements, they are indirect techniques, which rely on thermodynamic assumptions, which limit their applicability. While membrane osmometry (MO) provides a potentially unlimited direct measurement of osmotic pressure and solution osmolality, the conventional technique is often time-consuming and difficult to operate. In the present work, a novel membrane osmometer is presented. The instrument significantly reduces the conventional MO measurement time and is not subject to the limitations of VPO and FPO. For this paper, the osmotic pressure of aqueous sucrose solutions was collected in a molality range 0-5.5, by way of demonstration of the new instrument. When compared with data found in the literature, the experimental data were generally in good agreement. However, differences among results from the three techniques were observed.

  17. 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…

  18. 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

  19. 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.

  20. The initial freezing point temperature of beef rises with the rise in pH: a short communication.

    PubMed

    Farouk, M M; Kemp, R M; Cartwright, S; North, M

    2013-05-01

    This study tested the hypothesis that the initial freezing point temperature of meat is affected by pH. Sixty four bovine M. longissimus thoracis et lumborum were classified into two ultimate pH groups: low (<5.8) and high pH (>6.2) and their cooling and freezing point temperatures were determined. The initial freezing temperatures for beef ranged from -0.9 to -1.5°C (∆=0.6°C) with the higher and lower temperatures associated with high and low ultimate pH respectively. There was a significant correlation (r=+0.73, P<0.01) between beef pH and freezing point temperature in the present study. The outcome of this study has implications for the meat industry where evidence of freezing (ice formation) in a shipment as a result of high pH meat could result in a container load of valuable chilled product being downgraded to a lower value frozen product.

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

    NASA Astrophysics Data System (ADS)

    Fellmuth, Bernd; Hill, Kenneth D.

    2006-02-01

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

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

    PubMed

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

    2009-03-01

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

  3. Mechanism of carbachol-evoked contractions of guinea-pig ileal smooth muscle close to freezing point.

    PubMed Central

    Blackwood, A. M.; Bolton, T. B.

    1993-01-01

    1. The effect of lowering the temperature to near freezing-point upon the contractions and [3H]-inositol phosphate responses to carbachol were investigated in longitudinal smooth muscle from the guinea-pig ileum. 2. The peak amplitude of the contraction to a single application of 100 microM carbachol was the same at 37 degrees C and temperatures near freezing-point. However, the sensitivity to carbachol was reduced upon lowering the temperature and the time to peak contraction was increased from 5-10 s to 2-10 min. Even when the temperature was maintained near freezing-point, washing off carbachol produced a relaxation and eventual return of tension to basal levels. 3. Incubating the tissue in 140 mM K+, calcium-free solution or in calcium channel antagonists significantly reduced the carbachol-induced contraction to 10-30% of the control at 37 degrees C and also at 3 degrees C. Thus the majority of the activator calcium required for contraction entered the tissue via voltage-dependent calcium channels (VDCs) at both 37 degrees C and 3 degrees C. 4. The contractions produced by high potassium solutions were less at temperatures close to freezing-point than those at 37 degrees C suggesting that voltage-dependent calcium entry was inhibited as the temperature was lowered. 5. A small part of the contractile response to 100 microM carbachol was resistant to the removal of extracellular calcium at both 37 degrees C and 3 degrees C and this component was increased under depolarizing conditions.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8401915

  4. 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 ...

  5. 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, .

  6. Apathy, alexithymia, and depressive symptoms: Points of convergence and divergence.

    PubMed

    Ready, Rebecca E; Mather, Molly A; Santorelli, Gennarina D; Santospago, Breanna P

    2016-10-30

    This study determined convergence and divergence in the constructs of alexithymia, apathy, and depressive symptoms. Understanding of similarities and differences between these constructs will improve diagnostic accuracy for clinical and research purposes. Community-dwelling participants (N=622, M age=35.6 years, SD=13.1) completed online measures of alexithymia, depression, and apathy; 12.2% were alexithymic, 37.8% reported significant depressive symptoms, and 24.9% reported significant apathy. Exploratory Factor Analyses (EFAs) determined the best factor structure for the apathy, alexithymia, and depressive symptoms was comprised of three factors and accounted for 45.1% of item variance. The Depression, Apathy, and Alexithymia factors were defined most strongly by item content that is at the core of each construct. Depression was defined most highly by items assessing sadness, low self-esteem, and loneliness. The strongest item loadings for Alexithymia were difficulty identifying and describing feelings. Apathy was characterized by poor motivation, low interest, and lack of initiative. However, each of these core and defining features had significant cross-loadings on one of the other two factors. Negative affect shared variance with Apathy, low motivation shared variance with Depression, and difficulty describing and identify feelings shared variance with Depression and Apathy. Clinical and research implications are discussed. PMID:27512920

  7. 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.

  8. 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…

  9. 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.

  10. 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.

  11. 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.

  12. 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 μm 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 μm 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 μm 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.

  13. Efficacy of Nepeta Menthoides Boiss and Buhse Freeze-Dried Aqueous Extract on Anxiety of Patients with Depression: A Double-Blind Randomized Controlled Clinical Trial

    PubMed Central

    Firoozabadi, Ali; Kolouri, Sepideh; Zarshenas, Mohammad M.; Salehi, Alireza; Mosavat, Seyed Hamdollah; Dastgheib, Seyed Ali

    2016-01-01

    Background: The efficacy and safety of Nepeta menthoides freeze-dried aqueous extract were assessed on the anxiety of patients suffering from depression. Method: Patients received either N. menthoides formulation (400 mg/BID) or Sertraline (50 mg/BID) for 4 weeks. The Beck Anxiety Inventory (BAI) scales were used to assess the anxiety in two-week intervals (2nd, 4th, and 6th weeks). Folin-Ciocalteu and Dowd methods were used to determine the formulation of total phenol and flavonoid contents. Results: Compared with Sertraline, N. menthoides showed a higher reduction in BAI scores in the 2nd (16.52±8.07 vs. 21.38±10.98, P<0.05) and 4th week (11.55±6.74 vs. 20.47±11.53, P<0.05) along with a reduction in the recurrence rate and side effects. Total phenolic and flavonoid contents revealed in the presence of 127.09±0.43 mg GAE/g and 16.93±0.09 mg Q/g of extract. Conclusion: N. menthoides could be effective in the control and introducing a delay in recurrence of anxiety in patients with depression. PMID:27516672

  14. 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.

  15. Depression

    MedlinePlus

    ... make negative thinking worse. previous continue Depression Can Go Unrecognized People with depression may not realize they ... themselves or who have eating disorders or who go through extreme mood changes may have unrecognized depression. ...

  16. Depression

    MedlinePlus

    ... The depression generally lifts during spring and summer. Bipolar disorder is different from depression but is included in this list is because someone with bipolar disorder experiences episodes of extreme low moods (depression). But ...

  17. Ice growth in supercooled solutions of a biological "antifreeze", AFGP 1-5: an explanation in terms of adsorption rate for the concentration dependence of the freezing point.

    PubMed

    Knight, C A; DeVries, A L

    2009-07-21

    It is widely accepted, and we agree, that the lowering of the temperature at which ice can grow in a water solution of one of the biological antifreezes is a result of adsorption of the antifreeze molecules at the ice surface. However, how this can produce a well-defined "freezing point" that varies with the solution concentration has remained problematical. The results of a series of measurements of ice growing in supercooled solutions of an effective antifreeze are reported and interpreted in terms of this fundamental problem. It seemed that the solution of the problem would have to rely upon adsorption rate, because that appeared to be the only way for the concentration in solution to be so important. The crystal growth results are most unusual, and appear to confirm this. The growth rates over a wide range of antifreeze concentration in solution (about 0.05 to 9 mg ml(-1)) are zero from the thermodynamic freezing point down to the "non-equilibrium" freezing point, where there is a very sudden increase to a plateau value that then remains about constant as the supercooling is increased by about 2 degrees C. The plateau values of growth rate are faster than those from pure water at the lower-supercooling ends of the plateaus, but slower at higher supercooling, until the growth rate starts rising toward that from pure water. These plateau values of growth rate increase markedly with increasing concentration of the antifreeze in solution. Along with these changes there are complex changes in the growth orientations, from c-axis spicules in the plateaus to those more characteristic of growth from pure water at greater supercooling. We conclude that the non-equilibrium freezing point is determined by the adsorption rate. It is the warmest temperature at which the ice growth rate on the basal plane (where the antifreeze does not adsorb) is fast enough to prevent the area of basal face on a growing ice crystal from becoming too small to grow, which is determined in

  18. Surface freezing of water.

    PubMed

    Pérez-Díaz, J L; Álvarez-Valenzuela, M A; Rodríguez-Celis, F

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered-exclusively-by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided. PMID:27330895

  19. Surface freezing of water.

    PubMed

    Pérez-Díaz, J L; Álvarez-Valenzuela, M A; Rodríguez-Celis, F

    2016-01-01

    Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered-exclusively-by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on humidity, presenting at least three different types of surface crystals. Humidity triggers surface freezing as soon as it overpasses a defined value for a given temperature, generating a plurality of nucleation nodes. An evidence of simultaneous nucleation of surface ice crystals is also provided.

  20. A molecular simulation study of freezing/melting phenomena for Lennard-Jones methane in cylindrical nanoscale pores

    SciTech Connect

    Maddox, M.W.; Gubbins, K.E.

    1997-12-01

    A combination of grand canonical Monte Carlo and molecular dynamics simulation techniques are used to study the freezing and melting of Lennard-Jones methane in several different cylindrical pores. Two different types of pore wall are considered; a strongly attractive wall, and a weakly attractive wall, each with pore diameters in the range 1.5{endash}3.5 nm. Freezing point depression is observed in the case of the weakly attractive pores, in agreement with several experimental studies. Freezing point elevation is observed at the walls of the strongly attractive pore, but freezing point depression occurs at the center of such pores, due to geometrical constraints. {copyright} {ital 1997 American Institute of Physics.}

  1. TOPICAL REVIEW: Confinement effects on freezing and melting

    NASA Astrophysics Data System (ADS)

    Christenson, Hugo K.

    2001-03-01

    A review of experimental work on freezing and melting in confinement is presented. A range of systems, from metal oxide gels to porous glasses to novel nanoporous materials, is discussed. Features such as melting-point depression, hysteresis between freezing and melting, modifications to bulk solid structure and solid-solid transitions are reviewed for substances such as helium, organic fluids, water and metals. Recent work with well characterized assemblies of cylindrical pores like MCM-41 and graphitic microfibres with slit pores has suggested that the macroscopic picture of melting and freezing breaks down in pores of molecular dimensions. Applications of the surface force apparatus to the study of freezing and melting phenomena in confinement are discussed in some detail. This instrument is unique in allowing the study of conditions in a single pore, without the complications of pore blockage and connectivity effects. The results have confirmed the classical picture of melting-point depression in larger pores, and allowed the direct observation of capillary condensation of solid from vapour. Other results include the measurement of solvation forces across apparently fluid films below the bulk melting point and a solid-like response to shear of films above the bulk melting point. These somewhat contradictory findings highlight the difficulty of using bulk concepts to define the phase state of a substance confined to nanoscale pores.

  2. Depression.

    PubMed

    Stewart, Donna E; Gucciardi, Enza; Grace, Sherry L

    2004-08-25

    HEALTH ISSUE: Depression causes significant distress or impairment in physical, social, occupational and other key areas of functioning. Women are approximately twice as likely as men to experience depression. Psychosocial factors likely mediate the risks for depression incurred by biological influences. KEY FINDINGS: Data from the 1999 National Population Health Survey show that depression is more common among Canadian women, with an annual self-reported incidence of 5.7% compared with 2.9% in men. The highest rates of depression are seen among women of reproductive age. Predictive factors for depression include previous depression, feeling out of control or overwhelmed, chronic health problems, traumatic events in childhood or young adulthood, lack of emotional support, lone parenthood, and low sense of mastery. Although depression is treatable, only 43% of depressed women had consulted a health professional in 1998/99 and only 32.4% were taking antidepressant medication. People with lower education, inadequate income, and fewer contacts with a health professional were less likely to receive depression treatment. DATA GAPS AND RECOMMENDATIONS: A better understanding of factors that increase vulnerability and resilience to depression is needed. There is also a need for the collection and analysis of data pertaining to: prevalence of clinical anxiety; the prevalence of depression band 12 months after childbirth factors contributing to suicide contemplation and attempts among adolescent girls, current treatments for depression and their efficacy in depressed women at different life stages; interprovincial variation in depression rates and hospitalizations and the impact and costs of depression on work, family, individuals, and society.

  3. Freezing of stratospheric aerosol droplets

    SciTech Connect

    Luo, B.; Peter, T.; Crutzen, P. )

    1994-06-22

    The authors discuss the freezing of sulfuric acid droplets under stratospheric conditions from a thermodynamic point of view. They argue that the primary candidate for freezing is likely to be sulfuric acid tetrahydrate (H[sub 2]SO[sub 4][center dot]4H[sub 2]O). Their theoretical results suggest that the homogeneous freezing rate of this molecule is too low at stratospheric temperatures to explain measured results. Thus experimental values are likely to be due to heterogeneous freezing. This means that an appropriate nuclei must be present for freezing to commence, and has implications also for the formation of nitric acid trihydrates in the stratosphere.

  4. Numerical sensitivity studies on the impact of aerosol properties and drop freezing modes on the glaciation, microphysics, and dynamics of clouds

    NASA Astrophysics Data System (ADS)

    Diehl, K.; Simmel, M.; Wurzler, S.

    2006-04-01

    Numerical simulations were performed to investigate the effects of drop freezing in immersion and contact modes for a convective situation. For the description of heterogeneous drop freezing, new approaches were used considering the significantly different ice nucleating efficiencies of various ice nuclei. An air parcel model with a sectional two-dimensional description of the cloud microphysics was employed. Sensitivity studies were undertaken by varying the insoluble particle types as well as the soluble fraction of the aerosol particles showing the effects of these parameters on drop freezing and their possible impact on the vertical cloud dynamics. The soluble fraction ɛ decides whether immersion or contact freezing will be the major process. For high ɛ values, immersion freezing is the dominant process. In such cases the freezing process is strongly temperature-dependent, and the ice nucleation efficiency of the insoluble particle types becomes important for efficient freezing. The freezing point depression can be neglected because of the preferential freezing of large drops. Contact freezing is the major process in cases of lower ɛ values. In these cases the freezing process is less dependent on temperature and aerosol particle type. For conditions of efficient freezing, cold, high-altitude, completely glaciated clouds could form. The presented approaches for immersion and contact freezing can be incorporated further into mesoscale and global models to estimate the effects of specific ice nuclei on ice formation.

  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. Development of a complex type of pour point-viscosity depressant and infrared spectrum research

    SciTech Connect

    Zhang Fusheng; Wang Biao

    1995-11-01

    EMS, a complex type of pour point-viscosity depressant for crudes, is composed of EVA, MVA [molecular structure shown for both in the paper] and Surfactant. After adding EMS into the crudes, a very nice result in reducing pour point and viscosity for Daqing, Jianghan and Jidong crudes was obtained. From the research result of infrared spectroscopy of the interactions between EMS or its components and wax or mixture of resin and asphaltene isolated from three crudes, it has been shown that the area ratio of the double absorption peaks of 719 cm{sup {minus}1} and 729 cm{sup {minus}1} or 1,368 cm{sup {minus}1} and 1,378 cm{sup {minus}1} changed remarkably after EMS or its components were added into wax. It can be inferred that the cocrystallization probably happened between the EMS or its components and the wax. The position of the 4,000--3,000 cm{sup {minus}1} infrared absorption peak of the mixture of resin and asphaltene moved to the lower wavenumber, and the ratio of the area of 1,373 cm{sup {minus}1} absorption peak (methyl) to the combination area of 748, 810 and 871 cm{sup {minus}1} absorption peak (aromatics) increased remarkably. It can be inferred that the pour point-viscosity depressant molecules destroyed the original hydrogen bonds and overlapping of the aromatic ring planes among resin and asphaltene molecules to form a new cubic molecular structure and new hydrogen bonds with the results the viscosity of crude oil will be reduced.

  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. 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.

  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.

    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…

  11. Freezing stresses and hydration of isolated cell walls.

    PubMed

    Yoon, Yonghyeon; Pope, Jim; Wolfe, Joe

    2003-06-01

    The hydration of the cell walls of the giant alga Chara australis was measured as a function of temperature using quantitative deuterium nuclear magnetic resonance (NMR) of samples hydrated with D2O. At temperatures 23-5K below freezing, the hydration ratio (the ratio of mass of unfrozen water in microscopic phases in the cell wall to the dry mass) increases slowly with increasing temperature from about 0.2 to 0.4. It then rises rapidly with temperature in the few Kelvin below the freezing temperature. The linewidth of the NMR signal varies approximately linearly with the reciprocal of the hydration ratio, and with the freezing point depression or water potential. These empirical relations may be useful in estimating cell wall water contents in heterogeneous samples.

  12. 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

  13. 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.

  14. 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

  15. Depression

    MedlinePlus

    ... newborns, as well as jitteriness, difficulty feeding, and low blood sugar after delivery. However, moms who stop medications can ... a kind of antidepressant for treating depression and anxiety disorders. However, a number of research studies show ...

  16. Melting Point Depression and Fast Diffusion in Nanostructured Brazing Fillers Confined Between Barrier Nanolayers

    NASA Astrophysics Data System (ADS)

    Kaptay, G.; Janczak-Rusch, J.; Jeurgens, L. P. H.

    2016-08-01

    Successful brazing using Cu-based nanostructured brazing fillers at temperatures much below the bulk melting temperature of Cu was recently demonstrated (Lehmert et al. in, Mater Trans 56:1015-1018, 2015). The Cu-based nano-fillers are composed of alternating nanolayers of Cu and a permeable, non-wetted AlN barrier. In this study, a thermodynamic model is derived to estimate the melting point depression (MPD) in such Cu/AlN nano-multilayers (NMLs) as function of the Cu nanolayer thickness. Depending on the melting route, the model predicts a MPD range of 238-609 K for Cu10nm/AlN10nm NMLs, which suggests a heterogeneous pre-melting temperature range of 750-1147 K (476-874 °C), which is consistent with experimental observations. As suggested by basic kinetic considerations, the observed Cu outflow to the NML surface at the temperatures of 723-1023 K (450-750 °C) can also be partially rationalized by fast solid-state diffusion of Cu along internal interfaces, especially for the higher temperatures.

  17. 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.

  18. Development of Flow and Heat Transfer During Filling a Pipeline with Water at the Pipe Wall Temperature Below the Freezing Point

    NASA Astrophysics Data System (ADS)

    Kitanin, É. L.; Smirnov, Yu. A.; Lebedev, M. E.

    2016-07-01

    The paper presents the technique of computing flow and heat transfer of water in a pipeline whose initial temperature is lower than the freezing point of water. A feature of the method is the possibility of calculating the process from the moment of pouring water into a pipe on the inner surface of whose wall a layer of ice is being formed. The system of equations describing the process involves nonstationary energy equations for the water flow, ice layer, and for the pipe wall. It is solved for each section of the pipeline passed by water in a small time interval in the process of filling the pipe and further flow. The Beginning computer program has been created and implemented in the Visual Basic language for numerical analysis of the process. The calculations made with the aid of this program allow one to estimate the possibility of appearance of an ice plug in the pipeline at the given temperature, water flow rate, pipeline diameter, and conditions of external heat transfer of water flow in the pipeline.

  19. Depression.

    PubMed

    Tallo, Donato

    2014-04-15

    Reading the CPD article was beneficial to my professional nursing practice and development. I gained a greater understanding of how depression is likely to exacerbate the effects of a physical illness or complicate the treatment of other health conditions. PMID:24712633

  20. 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

  1. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    PubMed

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

    2015-08-01

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

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

    PubMed

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

    2015-08-01

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

  5. 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…

  6. 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.

  7. 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…

  8. 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-}.

  9. Neofunctionalization of zona pellucida proteins enhances freeze-prevention in the eggs of Antarctic notothenioids

    PubMed Central

    Cao, Lixue; Huang, Qiao; Wu, Zhichao; Cao, Dong-dong; Ma, Zhanling; Xu, Qianghua; Hu, Peng; Fu, Yanxia; Shen, Yu; Chan, Jiulin; Zhou, Cong-zhao; Zhai, Wanying; Chen, Liangbiao

    2016-01-01

    The mechanisms by which the eggs of the Antarctic notothenioid fishes avoid freezing are not fully understood. Zona pellucida proteins (ZPs) are constituents of the chorion which forms a protective matrix surrounding the egg. Here we report occurrence of freezing temperature-related gene expansion and acquisition of unusual ice melting-promoting (IMP) activity in a family of Antarctic notothenioid ZPs (AnnotoZPs). Members of AnnotoZPs are shown to bind with ice and non-colligatively depress the melting point of a solution in a range of 0.26 to 0.65 °C at a moderate concentration. Eggs of zebrafishes expressing an AnnotoZP transgene show improved melting point depression and enhanced survival in freezing conditions. Mutational analyses in a representative AnnotoZP indicate the ZP domain and patches of acidic residues are essential structures for the IMP activity. AnnotoZPs, therefore, represent a group of macromolecules that prevent freezing by a unique ZP–ice interaction mechanism distinct from the known antifreeze proteins. PMID:27698404

  10. Neofunctionalization of zona pellucida proteins enhances freeze-prevention in the eggs of Antarctic notothenioids

    NASA Astrophysics Data System (ADS)

    Cao, Lixue; Huang, Qiao; Wu, Zhichao; Cao, Dong-Dong; Ma, Zhanling; Xu, Qianghua; Hu, Peng; Fu, Yanxia; Shen, Yu; Chan, Jiulin; Zhou, Cong-Zhao; Zhai, Wanying; Chen, Liangbiao

    2016-10-01

    The mechanisms by which the eggs of the Antarctic notothenioid fishes avoid freezing are not fully understood. Zona pellucida proteins (ZPs) are constituents of the chorion which forms a protective matrix surrounding the egg. Here we report occurrence of freezing temperature-related gene expansion and acquisition of unusual ice melting-promoting (IMP) activity in a family of Antarctic notothenioid ZPs (AnnotoZPs). Members of AnnotoZPs are shown to bind with ice and non-colligatively depress the melting point of a solution in a range of 0.26 to 0.65 °C at a moderate concentration. Eggs of zebrafishes expressing an AnnotoZP transgene show improved melting point depression and enhanced survival in freezing conditions. Mutational analyses in a representative AnnotoZP indicate the ZP domain and patches of acidic residues are essential structures for the IMP activity. AnnotoZPs, therefore, represent a group of macromolecules that prevent freezing by a unique ZP-ice interaction mechanism distinct from the known antifreeze proteins.

  11. 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.

  12. 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.

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

    PubMed

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

    2009-05-21

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

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

    PubMed

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

    2009-05-21

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

  15. Freeze Prediction Model

    NASA Technical Reports Server (NTRS)

    Morrow, C. T. (Principal Investigator)

    1981-01-01

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

  16. Optical detection of melting point depression for silver nanoparticles via in situ real time spectroscopic ellipsometry

    NASA Astrophysics Data System (ADS)

    Little, S. A.; Begou, T.; Collins, R. W.; Marsillac, S.

    2012-01-01

    Silver nanoparticle films were deposited by sputtering at room temperature and were annealed while monitoring by real time spectroscopic ellipsometry (SE). The nanoparticle dielectric functions (0.75 eV-6.5 eV) obtained by SE were modeled using Lorentz and generalized oscillators for the nanoparticle plasmon polariton (NPP) and interband transitions, respectively. The nanoparticle melting point could be identified from variations in the oscillator parameters during annealing, and this identification was further confirmed after cooling through significant, irreversible changes in these parameters relative to the as-deposited film. The variation in melting point with physical thickness, and thus average nanoparticle diameter, as measured by SE enables calculation of the surface energy density.

  17. Depression, anxiety and their comorbidity in the Swedish general population: point prevalence and the effect on health-related quality of life

    PubMed Central

    Carlbring, Per; Heedman, Åsa; Paxling, Björn; Andersson, Gerhard

    2013-01-01

    Background. Depression and anxiety disorders are major world-wide problems. There are no or few epidemiological studies investigating the prevalence of depression, generalized anxiety disorder and anxiety disorders in general in the Swedish population. Methods. Data were obtained by means of a postal survey administered to 3001 randomly selected adults. After two reminders response rate was 44.3%. Measures of depression and general anxiety were the 9-item Patient Health Questionnaire Depression Scale (PHQ-9) and the 7-item Generalized Anxiety Disorder Scale (GAD-7). The PHQ-9 identified participants who had experienced clinically significant depression (PHQ-9 ≥ 10), and who had a diagnosis of major depression (defined by using a PHQ-9 scoring algorithm). Clinically significant anxiety was defined as having a GAD-7 score ≥ 8. To specifically measure generalized anxiety disorder, the Generalized Anxiety Disorder Questionnaire-IV (GAD-Q-IV) was used with an established cut-off. Health-related quality of life was measured using the EuroQol (EQ-5D). Experiences of treatments for psychiatric disorders were also assessed. Results. Around 17.2% (95% CI: 15.1–19.4) of the participants were experiencing clinically significant depression (10.8%; 95% CI: 9.1–12.5) and clinically significant anxiety (14.7%; 95% CI: 12.7–16.6). Among participants with either clinically significant depression or anxiety, nearly 50% had comorbid disorders. The point prevalence of major depression was 5.2% (95% CI: 4.0–6.5), and 8.8% (95% CI: 7.3–10.4) had GAD. Among those with either of these disorders, 28.2% had comorbid depression and GAD. There were, generally, significant gender differences, with more women having a disorder compared to men. Among those with depression or anxiety, only between half and two thirds had any treatment experience. Comorbidity was associated with higher symptom severity and lower health-related quality of life. Conclusions. Epidemiological data from

  18. Fundamentals of freeze-drying.

    PubMed

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

    2002-01-01

    --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

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

    PubMed

    Medeiros, Juliana S; Pockman, William T

    2011-01-01

    Drought and freezing are both known to limit desert plant distributions, but the interaction of these stressors is poorly understood. Drought may increase freezing tolerance in leaves while decreasing it in the xylem, potentially creating a mismatch between water supply and demand. To test this hypothesis, we subjected Larrea tridentata juveniles grown in a greenhouse under well-watered or drought conditions to minimum temperatures ranging from -8 to -24 °C. We measured survival, leaf retention, gas exchange, cell death, freezing point depression and leaf-specific xylem hydraulic conductance (k₁). Drought-exposed plants exhibited smaller decreases in gas exchange after exposure to -8 °C compared to well-watered plants. Drought also conferred a significant positive effect on leaf, xylem and whole-plant function following exposure to -15 °C; drought-exposed plants exhibited less cell death, greater leaf retention, higher k₁ and higher rates of gas exchange than well-watered plants. Both drought-exposed and well-watered plants experienced 100% mortality following exposure to -24 °C. By documenting the combined effects of drought and freezing stress, our data provide insight into the mechanisms determining plant survival and performance following freezing and the potential for shifts in L. tridentata abundance and range in the face of changing temperature and precipitation regimes. PMID:20825578

  20. Freezing and Food Safety

    MedlinePlus

    ... Freezer Burn Color Changes Freeze Rapidly Freezer - Refrigerator Temperatures Freezer Storage Time Safe Thawing Refreezing Cooking Frozen ... parasites can be destroyed by sub-zero freezing temperatures. However, very strict government-supervised conditions must be ...

  1. KEY COMPARISON: Final report on EUROMET.T-K4 (EUROMET Project 820): Comparison of the realizations of the ITS-90 at the freezing points of Al (660.323 °C) and Ag (961.78 °C)

    NASA Astrophysics Data System (ADS)

    Heyer, D.; Noatsch, U.; Tegeler, E.; Anagnostou, M.; Turzo-Andras, E.; Antonsen, I.; Augevicius, V.; Bojkovski, J.; Bronnum, A.; Chimenti, V.; Duris, S.; Filipe, E.; Gaita, S.; Gray, J.; Head, D.; Grudniewicz, E.; Ivarsson, J.; Kalemci, M.; Kerkhof, O.; Lobo, I.; Nemeth, S.; Pokhodun, A.; Ranostaj, J.; Renaot, E.; Rosenkranz, P.; Smid, M.; Steur, P.; Steiner, A.; Valin, M.; Veliki, T.; Weckström, T.

    2008-01-01

    The comparison EUROMET.T-K4 is the regional extension of CCT-K4: an intercomparison of the realisations of the freezing points of Al (660.323 °C) and Ag (961.78 °C). The intercomparison was organized in four loops with long stem standard platinum resistance thermometers (SPRTs) as travelling standards: One 25 Ω thermometer to be used only at the Al freezing point and two high temperature SPRTs to be used only at the Ag freezing point in each loop. Parallel to the measurements with thermometers the pilot and sub-pilots organized an internal intercomparison using an Ag fixed point cell. Most HTSPRTs showed a strong drift which is mainly due to mechanical stress and poisoning of the sensor by impurities. This drift can partly be compensated by a correction applying Matthiessen's rule. An evaluation of the data taking into account both HTSPRTs in each loop, the linkage of the sub-pilots by measurements at the Ag freezing point and a possible compensation according to Matthiessens's rule allows to calculate the results of the participants also for the measurements at the Ag freezing point. European reference values (ERV) were calculated for measurements at the Al and Ag freezing points. The difference between these ERVs and the corresponding KCRVs of CCT-K4 is also given, which allows the linking of the different comparisons. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCT, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  2. Fundamentals of freeze-drying.

    PubMed

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

    2002-01-01

    --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

  3. New High-Performance Droplet Freezing Assay (HP-DFA) for the Analysis of Ice Nuclei with Complex Composition

    NASA Astrophysics Data System (ADS)

    Kunert, Anna Theresa; Scheel, Jan Frederik; Helleis, Frank; Klimach, Thomas; Pöschl, Ulrich; Fröhlich-Nowoisky, Janine

    2016-04-01

    Freezing of water above homogeneous freezing is catalyzed by ice nucleation active (INA) particles called ice nuclei (IN), which can be of various inorganic or biological origin. The freezing temperatures reach up to -1 °C for some biological samples and are dependent on the chemical composition of the IN. The standard method to analyze IN in solution is the droplet freezing assay (DFA) established by Gabor Vali in 1970. Several modifications and improvements were already made within the last decades, but they are still limited by either small droplet numbers, large droplet volumes or inadequate separation of the single droplets resulting in mutual interferences and therefore improper measurements. The probability that miscellaneous IN are concentrated together in one droplet increases with the volume of the droplet, which can be described by the Poisson distribution. At a given concentration, the partition of a droplet into several smaller droplets leads to finely dispersed IN resulting in better statistics and therefore in a better resolution of the nucleation spectrum. We designed a new customized high-performance droplet freezing assay (HP-DFA), which represents an upgrade of the previously existing DFAs in terms of temperature range and statistics. The necessity of observing freezing events at temperatures lower than homogeneous freezing due to freezing point depression, requires high-performance thermostats combined with an optimal insulation. Furthermore, we developed a cooling setup, which allows both huge and tiny temperature changes within a very short period of time. Besides that, the new DFA provides the analysis of more than 750 droplets per run with a small droplet volume of 5 μL. This enables a fast and more precise analysis of biological samples with complex IN composition as well as better statistics for every sample at the same time.

  4. Freezing resistance in polar fishes.

    PubMed

    Hargens, A R

    1972-04-14

    Arctic and antarctic fishes, living in contact with sea ice at -1.9 degrees C, have plasma equilibrium freezing points near -1.2 degrees C which are dependent on salt concentrations. These supercooled fishes have plasma protein concentrations much higher than other polar animals have, and the proteins impede ice propagation at temperatures down to -2 degrees C. Plasma protein concentration increases as environmental water temperature decreases. PMID:17843537

  5. Validity of a portable urine refractometer: the effects of sample freezing.

    PubMed

    Sparks, S Andy; Close, Graeme L

    2013-01-01

    The use of portable urine osmometers is widespread, but no studies have assessed the validity of this measurement technique. Furthermore, it is unclear what effect freezing has on osmolality. One-hundred participants of mean (±SD) age 25.1 ± 7.6 years, height 1.77 ± 0.1 m and weight 77.1 ± 10.8 kg provided single urine samples that were analysed using freeze point depression (FPD) and refractometry (RI). Samples were then frozen at -80°C (n = 81) and thawed prior to re-analysis. Differences between methods and freezing were determined using Wilcoxon's signed rank test. Relationships between measurements were assessed using intraclass correlation coefficients (ICC) and typical error of estimate (TE). Osmolality was lower (P = 0.001) using RI (634.2 ± 339.8 mOsm · kgH2O(-1)) compared with FPD (656.7 ± 334.1 mOsm · kgH2O(-1)) but the TE was trivial (0.17). Freezing significantly reduced mean osmolality using FPD (656.7 ± 341.1 to 606.5 ± 333.4 mOsm · kgH2O(-1); P < 0.001), but samples were still highly related following freezing (ICC, r = 0.979, P < 0.001, CI = 0.993-0.997; TE = 0.15; and r=0.995, P < 0.001, CI = 0.967-0.986; TE = 0.07 for RI and FPD respectively). Despite mean differences between methods and as a result of freezing, such differences are physiologically trivial. Therefore, the use of RI appears to be a valid measurement tool to determine urine osmolality. PMID:23205563

  6. Validity of a portable urine refractometer: the effects of sample freezing.

    PubMed

    Sparks, S Andy; Close, Graeme L

    2013-01-01

    The use of portable urine osmometers is widespread, but no studies have assessed the validity of this measurement technique. Furthermore, it is unclear what effect freezing has on osmolality. One-hundred participants of mean (±SD) age 25.1 ± 7.6 years, height 1.77 ± 0.1 m and weight 77.1 ± 10.8 kg provided single urine samples that were analysed using freeze point depression (FPD) and refractometry (RI). Samples were then frozen at -80°C (n = 81) and thawed prior to re-analysis. Differences between methods and freezing were determined using Wilcoxon's signed rank test. Relationships between measurements were assessed using intraclass correlation coefficients (ICC) and typical error of estimate (TE). Osmolality was lower (P = 0.001) using RI (634.2 ± 339.8 mOsm · kgH2O(-1)) compared with FPD (656.7 ± 334.1 mOsm · kgH2O(-1)) but the TE was trivial (0.17). Freezing significantly reduced mean osmolality using FPD (656.7 ± 341.1 to 606.5 ± 333.4 mOsm · kgH2O(-1); P < 0.001), but samples were still highly related following freezing (ICC, r = 0.979, P < 0.001, CI = 0.993-0.997; TE = 0.15; and r=0.995, P < 0.001, CI = 0.967-0.986; TE = 0.07 for RI and FPD respectively). Despite mean differences between methods and as a result of freezing, such differences are physiologically trivial. Therefore, the use of RI appears to be a valid measurement tool to determine urine osmolality.

  7. 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…

  8. Influence of melt freezing characteristics on steam explosion energetics

    SciTech Connect

    Okkonen, T.; Sehgal, B.R.

    1996-08-01

    This paper examines the freezing process of distinct melt particles interacting with water. Approximate time scales of freezing are estimated for some high-temperature melt materials that are of interest in experimental and reactor situations. Transient conduction calculations are performed to clarify the special freezing characteristics of oxidic melt materials (low conductivity) and binary melt mixtures (no definite freezing point). The transient calculations are compared with recent experiments indicating ``non-explosivity`` of Corium (UO{sub 2}-ZrO{sub 2}). One potential explanation, based on the freezing characteristics of binary Corium mixture, is proposed for the experimental observations. The numerical results are generalized by discussing the scaling implications of the thermal conduction analysis and by defining different freezing categories. Finally, conclusions are drawn on the potential influence of melt freezing characteristics on steam explosion energetic.

  9. 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.

  10. 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.

  11. Surface freezing of n-octane nanodroplets

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  12. The Effects of Social Economic Status, Social Support, Gender, Ethnicity and Grade Point Average on Depression among College Students.

    ERIC Educational Resources Information Center

    Ndoh, Sunday; Scales, Josie

    Previous research has indicated that depression, the most common psychological disorder experienced by over 19 million Americans, can be related to such factors as ethnicity, social support, social economic status, academic achievement and gender. One hundred and sixty students from Johnson C. Smith University and Tennessee State University were…

  13. Modeling Soil Freezing Dynamics

    NASA Astrophysics Data System (ADS)

    Flerchinger, G. N.; Seyfried, M. S.; Hardegree, S. P.

    2002-12-01

    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 permeability of the soil. This is aggravated by the tendency of water to migrate to the freezing front, causing elevated ice content and frost heave. Freezing and thawing of the soil are controlled by the complex interactions of heat and water transfer at the soil surface governed by meteorological and environmental conditions at the soil-atmosphere interface. Soil freezing dynamics including liquid water content, infiltration, and runoff simulated by the Simultaneous Heat and Water (SHAW) Model were tested at three field locations in southwest Idaho. Sites included: three soil types at the Orchard Field Test Site; bare and sagebrush-covered runoff plots at the Lower Sheep Creek site on the Reynolds Creek Experimental Watershed; and runoff plots on steep mountainous slopes on the Boise Front. Detailed simulations of soil freezing and thawing were conducted specifically to examine the dynamics of liquid water content during freezing and thawing. Freezing/thawing processes, including liquid water content and runoff, were simulated well.

  14. 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.

  15. 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.

  16. Two-dimensional freezing criteria for crystallizing colloidal monolayers.

    PubMed

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

    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 Lowen-Palberg-Simon dynamical freezing criterion, and two other rules based, respectively, on the split shoulder of the radial distribution function and on the distribution of the shape factor of Voronoi polygons. Importantly, these freezing criteria, usually applied in the context of single crystals, were demonstrated to apply to the formation of polycrystalline solids. At the freezing point, we also observed a peak in the fluctuations of the orientational order parameter and a percolation transition associated with caged particles. Speculation about these percolated clusters of caged particles casts light on solidification mechanisms and dynamic heterogeneity in freezing. PMID:20423183

  17. 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.

  18. 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.

  19. 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.

  20. Avoidance and tolerance of freezing in ectothermic vertebrates.

    PubMed

    Costanzo, Jon P; Lee, Richard E

    2013-06-01

    Ectothermic vertebrates have colonized regions that are seasonally or perpetually cold, and some species, particularly terrestrial hibernators, must cope with temperatures that fall substantially below 0°C. Survival of such excursions depends on either freeze avoidance through supercooling or freeze tolerance. Supercooling, a metastable state in which body fluids remain liquid below the equilibrium freezing/melting point, is promoted by physiological responses that protect against chilling injury and by anatomical and behavioral traits that limit risk of inoculative freezing by environmental ice and ice-nucleating agents. Freeze tolerance evolved from responses to fundamental stresses to permit survival of the freezing of a substantial amount of body water under thermal and temporal conditions of ecological relevance. Survival of freezing is promoted by a complex suite of molecular, biochemical and physiological responses that limit cell death from excessive shrinkage, damage to macromolecules and membranes, metabolic perturbation and oxidative stress. Although freeze avoidance and freeze tolerance generally are mutually exclusive strategies, a few species can switch between them, the mode used in a particular instance of chilling depending on prevailing physiological and environmental conditions.

  1. Avoidance and tolerance of freezing in ectothermic vertebrates.

    PubMed

    Costanzo, Jon P; Lee, Richard E

    2013-06-01

    Ectothermic vertebrates have colonized regions that are seasonally or perpetually cold, and some species, particularly terrestrial hibernators, must cope with temperatures that fall substantially below 0°C. Survival of such excursions depends on either freeze avoidance through supercooling or freeze tolerance. Supercooling, a metastable state in which body fluids remain liquid below the equilibrium freezing/melting point, is promoted by physiological responses that protect against chilling injury and by anatomical and behavioral traits that limit risk of inoculative freezing by environmental ice and ice-nucleating agents. Freeze tolerance evolved from responses to fundamental stresses to permit survival of the freezing of a substantial amount of body water under thermal and temporal conditions of ecological relevance. Survival of freezing is promoted by a complex suite of molecular, biochemical and physiological responses that limit cell death from excessive shrinkage, damage to macromolecules and membranes, metabolic perturbation and oxidative stress. Although freeze avoidance and freeze tolerance generally are mutually exclusive strategies, a few species can switch between them, the mode used in a particular instance of chilling depending on prevailing physiological and environmental conditions. PMID:23678097

  2. SLAPex Freeze/Thaw 2015: The First Dedicated Soil Freeze/Thaw Airborne Campaign

    NASA Technical Reports Server (NTRS)

    Kim, Edward; Wu, Albert; DeMarco, Eugenia; Powers, Jarrett; Berg, Aaron; Rowlandson, Tracy; Freeman, Jacqueline; Gottfried, Kurt; Toose, Peter; Roy, Alexandre; Derksen, Chris; Royer, Alain; Belair, Stephane; Houser, Paul; McDonald, Kyle; Entin, Jared; Lewis, Kristen

    2016-01-01

    Soil freezing and thawing is an important process in the terrestrial water, energy, and carbon cycles, marking the change between two very different hydraulic, thermal, and biological regimes. NASA's Soil Moisture Active/Passive (SMAP) mission includes a binary freeze/thaw data product. While there have been ground-based remote sensing field measurements observing soil freeze/thaw at the point scale, and airborne campaigns that observed some frozen soil areas (e.g., BOREAS), the recently-completed SLAPex Freeze/Thaw (F/T) campaign is the first airborne campaign dedicated solely to observing frozen/thawed soil with both passive and active microwave sensors and dedicated ground truth, in order to enable detailed process-level exploration of the remote sensing signatures and in situ soil conditions. SLAPex F/T utilized the Scanning L-band Active/Passive (SLAP) instrument, an airborne simulator of SMAP developed at NASA's Goddard Space Flight Center, and was conducted near Winnipeg, Manitoba, Canada, in October/November, 2015. Future soil moisture missions are also expected to include soil freeze/thaw products, and the loss of the radar on SMAP means that airborne radar-radiometer observations like those that SLAP provides are unique assets for freeze/thaw algorithm development. This paper will present an overview of SLAPex F/T, including descriptions of the site, airborne and ground-based remote sensing, ground truth, as well as preliminary results.

  3. Study on the Realization of Zinc Point and the Zinc-Point Cell Comparison

    NASA Astrophysics Data System (ADS)

    Widiatmo, J. V.; Sakai, M.; Satou, K.; Yamazawa, K.; Tamba, J.; Arai, M.

    2011-01-01

    Continuing our study on aluminum, tin, and silver points, a study on the realization of the zinc point was conducted. Zinc-point cells were newly fabricated using 6N-nominal grade zinc samples, impurity elements of which were analyzed extensively based on glow-discharge mass spectrometry (GDMS). The present paper reports the temperature measurements done using the newly fabricated cells during the zinc freezing process, under which the zinc fixed point is defined, and the analysis of the freezing curve obtained. Comparisons of zinc-point temperatures realized by the newly fabricated cells (cell-to-cell comparisons) were also conducted. Zinc-point depression due to impurity elements was calculated based on the sum of individual estimates and the impurity element analysis. One of the cells evaluated was drawn out from its crucible and analyzed by GDMS at four points, namely, at around the center of the top, of the middle, of the bottom, and around the outer part of the middle area. The purpose of this cell disassembly is to see whether or not there has been some difference before and after cell fabrication, as well as difference in impurity element distribution within the ingot. From the aforementioned studies, some findings were obtained. First finding is that the homogeneity of the zinc ingot was within 30%, except for Pb, which was more concentrated in the center part. Second finding is that the cell-to-cell temperature difference changes along with the progressing solidification process. As a consequence, for an accurate cell-to-cell comparison, the locus in the freezing plateau where the comparison is done should be determined. Third finding is that the slope analysis estimates accurately the cell-to-cell comparison, and is consistent with the impurity analysis. This shows that the slope analysis gives extensive information about the effect of impurity to the zinc-point realization, especially after the cell fabrication.

  4. Thermodynamics of freezing and melting.

    PubMed

    Pedersen, Ulf R; Costigliola, Lorenzo; Bailey, Nicholas P; Schrøder, Thomas B; Dyre, Jeppe C

    2016-01-01

    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature-pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system. PMID:27530064

  5. Thermodynamics of freezing and melting

    PubMed Central

    Pedersen, Ulf R.; Costigliola, Lorenzo; Bailey, Nicholas P.; Schrøder, Thomas B.; Dyre, Jeppe C.

    2016-01-01

    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature–pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system. PMID:27530064

  6. Thermodynamics of freezing and melting.

    PubMed

    Pedersen, Ulf R; Costigliola, Lorenzo; Bailey, Nicholas P; Schrøder, Thomas B; Dyre, Jeppe C

    2016-08-17

    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature-pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system.

  7. Thermodynamics of freezing and melting

    NASA Astrophysics Data System (ADS)

    Pedersen, Ulf R.; Costigliola, Lorenzo; Bailey, Nicholas P.; Schrøder, Thomas B.; Dyre, Jeppe C.

    2016-08-01

    Although the freezing of liquids and melting of crystals are fundamental for many areas of the sciences, even simple properties like the temperature-pressure relation along the melting line cannot be predicted today. Here we present a theory in which properties of the coexisting crystal and liquid phases at a single thermodynamic state point provide the basis for calculating the pressure, density and entropy of fusion as functions of temperature along the melting line, as well as the variation along this line of the reduced crystalline vibrational mean-square displacement (the Lindemann ratio), and the liquid's diffusion constant and viscosity. The framework developed, which applies for the sizable class of systems characterized by hidden scale invariance, is validated by computer simulations of the standard 12-6 Lennard-Jones system.

  8. 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.

  9. 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)

  10. 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/ ...

  11. Freezing of Water Droplet due to Evaporation

    NASA Astrophysics Data System (ADS)

    Satoh, Isao; Fushinobu, Kazuyoshi; Hashimoto, Yu

    In this study, the feasibility of cooling/freezing of phase change.. materials(PCMs) due to evaporation for cold storage systems was experimentally examined. A pure water was used as the test PCM, since the latent heat due to evaporation of water is about 7 times larger than that due to freezing. A water droplet, the diameter of which was 1-4 mm, was suspended in a test cell by a fine metal wire (O. D.= 100μm),and the cell was suddenly evacuated up to the pressure lower than the triple-point pressure of water, so as to enhance the evaporation from the water surface. Temperature of the droplet was measured by a thermocouple, and the cooling/freezing behavior and the temperature profile of the droplet surface were captured by using a video camera and an IR thermo-camera, respectively. The obtained results showed that the water droplet in the evacuated cell is effectively cooled by the evaporation of water itself, and is frozen within a few seconds through remarkable supercooling state. When the initial temperature of the droplet is slightly higher than the room temperature, boiling phenomena occur in the droplet simultaneously with the freezing due to evaporation. Under such conditions, it was shown that the degree of supercooling of the droplet is reduced by the bubbles generated in the droplet.

  12. Freezing in the Antarctic limpet, Nacella concinna.

    PubMed

    Hawes, T C; Worland, M R; Bale, J S

    2010-08-01

    The process of organismal freezing in the Antarctic limpet, Nacella concinna, is complicated by molluscan biology. Internal ice formation is, in particular, mediated by two factors: (a) the provision of an inoculative target for ice formation in the exposed mucus-secreting foot; and (b) osmoconformity to the marine environment. With regard to the first, direct observations of the independent freezing of pedal mucus support the hypothesis that internal ice formation is delayed by the mucal film. As to the second, ice nucleation parametrics of organismal tissue (head, midgut, gonad, foot) and mucus in both inter- and subtidal populations were characterized by high melting points (range=-4.61 to -6.29 degrees C), with only c.50% of a given sample osmotically active. At this stage it would be premature to ascribe a cryo-adaptive function to the mucus as the protective effects are more readily attributed to the physical properties of the secretion (i.e. viscosity) and their corresponding effects on the rate of heat transfer. As it is difficult to thermally distinguish between the freezing of mucus and the rest of the animal, the question as to whether it is tolerant of internal as well as external ice formation remains problematic, although it may be well suited to the osmotic stresses of organismal freezing. PMID:20599885

  13. Seasonal accumulation of acetylated triacylglycerols by a freeze-tolerant insect.

    PubMed

    Marshall, Katie E; Thomas, Raymond H; Roxin, Aron; Chen, Eric K Y; Brown, Jason C L; Gillies, Elizabeth R; Sinclair, Brent J

    2014-05-01

    Most animals store energy as long-chain triacylglycerols (lcTAGs). Trace amounts of acetylated triacylglycerols (acTAGs) have been reported in animals, but are not accumulated, likely because they have lower energy density than lcTAGs. Here we report that acTAGs comprise 36% of the neutral lipid pool of overwintering prepupae of the goldenrod gall fly, Eurosta solidaginis, while only 17% of the neutral lipid pool is made up of typical lcTAGs. These high concentrations of acTAGs, present only during winter, appear to be synthesized by E. solidaginis and are not found in other freeze-tolerant insects, nor in the plant host. The mixture of acTAGs found in E. solidaginis has a significantly lower melting point than equivalent lcTAGs, and thus remains liquid at temperatures at which E. solidaginis is frozen in the field, and depresses the melting point of aqueous solutions in a manner unusual for neutral lipids. We note that accumulation of acTAGs coincides with preparation for overwintering and the seasonal acquisition of freeze tolerance. This is the first observation of accumulation of acTAGs by an animal, and the first evidence of dynamic interconversion between acTAGs and lcTAGs during development and in response to stress.

  14. Seasonal accumulation of acetylated triacylglycerols by a freeze-tolerant insect.

    PubMed

    Marshall, Katie E; Thomas, Raymond H; Roxin, Aron; Chen, Eric K Y; Brown, Jason C L; Gillies, Elizabeth R; Sinclair, Brent J

    2014-05-01

    Most animals store energy as long-chain triacylglycerols (lcTAGs). Trace amounts of acetylated triacylglycerols (acTAGs) have been reported in animals, but are not accumulated, likely because they have lower energy density than lcTAGs. Here we report that acTAGs comprise 36% of the neutral lipid pool of overwintering prepupae of the goldenrod gall fly, Eurosta solidaginis, while only 17% of the neutral lipid pool is made up of typical lcTAGs. These high concentrations of acTAGs, present only during winter, appear to be synthesized by E. solidaginis and are not found in other freeze-tolerant insects, nor in the plant host. The mixture of acTAGs found in E. solidaginis has a significantly lower melting point than equivalent lcTAGs, and thus remains liquid at temperatures at which E. solidaginis is frozen in the field, and depresses the melting point of aqueous solutions in a manner unusual for neutral lipids. We note that accumulation of acTAGs coincides with preparation for overwintering and the seasonal acquisition of freeze tolerance. This is the first observation of accumulation of acTAGs by an animal, and the first evidence of dynamic interconversion between acTAGs and lcTAGs during development and in response to stress. PMID:24790101

  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. 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.

  17. 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

  18. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., 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 requirements... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Freezing facilities. 590.534...

  19. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., 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 requirements... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Freezing facilities. 590.534...

  20. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., 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 requirements... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Freezing facilities. 590.534...

  1. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., 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 requirements... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Freezing facilities. 590.534...

  2. 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.

  3. [Depressive syndromes in adolescents].

    PubMed

    Branik, E

    1990-04-01

    First the difficulties with the concept of depression, its definition and with the classification and heterogeneity of the depressive syndromes are pointed out. The particular clinical importance of depressive states, especially of adolescents, is shown by means of epidemiological data. A case report illustrates the classification problems and a part of the typical conflicts and psychic demands in adolescence. Then follows a short survey on the conception of depressive states in psychoanalysis, with special reference to this age group. The evaluation of the given studies calls for interdisciplinary research, in order to tackle the still unsolved questions concerning depressive conditions and to improve the coordination of separate findings. PMID:2352911

  4. Freezing and melting of hydrogen confined in nanoporous silica.

    PubMed

    Kucheyev, S O; Van Cleve, E; Worsley, M A

    2014-06-01

    Thermodynamic properties of condensed hydrogen in geometric confinement remain poorly understood. Here, we use relaxation calorimetry to study solidification and melting of H2 in a series of Vycor-type nanoporous silica glasses with interconnected pores with average diameters in a wide range of ∼100-3000 Å. We find that the depression of freezing and melting temperatures for this quantum system follows the classical Gibbs-Thomson-like behavior, scaling inversely with the pore size when correlated to pore diameters measured directly by electron microscopy, rather than conventional gas sorption techniques. The shapes of pore size distributions derived from hydrogen thermoporometry are, however, more complex than those measured by gas sorption. The ratio between temperatures of the depression of freezing and melting suggests that the actual pore geometry in Vycor-type nanoporous glasses deviates from cylindrical. PMID:24823921

  5. Thermal properties of ration components as affected by moisture content and water activity during freezing.

    PubMed

    Li, J; Chinachoti, P; Wang, D; Hallberg, L M; Sun, X S

    2008-11-01

    Beef roast with vegetables is an example of a meal, ready-to-eat (MRE) ration entrée. It is a mixture of meat, potato, mushroom, and carrot with a gravy sauce. The thermal properties of each component were characterized in terms of freezing point, latent heat, freezable and unfreezable water contents, and enthalpy during freezing using differential scanning calorimetry. Freezing and thawing curves and the effect of freezing and thawing cycles on thermal properties were also evaluated. The freezing points of beef, potato, mushroom, and sauce were all in the range of -5.1 to -5.6 degrees C, but moisture content, water activity, latent heat, freezable and unfreezable water contents, and enthalpy varied among these components. Freezing temperature greatly affected the unfrozen water fraction. The unfreezable water content (unfrozen water fraction at -50 degrees C) of ration components was in the range of 8.2% to 9.7%. The freezing and thawing curves of vegetables with sauce differed from those of beef but took similar time to freeze or thaw. Freezing and thawing cycles did not greatly affect the thermal properties of each component. Freezing point and latent heat were reduced by decreasing moisture content and water activity of each component. Water activity was proportionally linear to freezing point at a(w) > 0.88, and moisture content was proportionally linear to freezable water content in all ration components. Water was not available for freezing when moisture content was reduced to 28.8% or less. This study indicates that moisture content and water activity are critical factors affecting thermal behavior of ration components during freezing.

  6. 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.

  7. Biohazards in pharmaceutical freeze drying.

    PubMed

    Hermanský, M; Graichman, T

    1990-01-01

    Among freeze-dried drugs there are many which may imperil manufacturing personnel, e.g. cytostatic drugs possessing carcinogenic effects. Production zones must be specially adapted for handling such drugs. There are many risks endangering a freeze-drying operation--power or water supply failure, but also improperly established freeze-drying cycle. A production batch of a rare, expensive and sensitive product represents a big value; modern equipment therefore features sophisticated automation, overriding possible human error. Problem of particulate contamination is less severe with vials stoppered inside the vacuum chamber, but rubber closures still may become a source of haze. Back-migration of oil from vacuum pumps may be another source. Economy of industrial freeze-drying may be much improved if freezing sequence, drying rate, adjustment of vacuum by "bleeding" nitrogen are tailored specially for each particular product.

  8. 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.

  9. Freezing in Sealed Capillaries for Preparation of Frozen Hydrated Sections

    PubMed Central

    Yakovlev, Sergey; Downing, Kenneth H.

    2014-01-01

    We have investigated the freezing of specimens in a confined volume for preparation of vitreous samples for cryosectioning. With 15% dextran as a cryoprotectant, a sample sealed in a copper tube begins to freeze into crystalline ice when plunged into liquid ethane. Crystallization rapidly causes an increase in the pressure to the point that much of the sample freezes in a vitreous state. We used synchrotron X-ray diffraction of samples frozen with various amounts of dextran to characterize the ice phases and crystal orientation, providing insights on the freezing process. We have characterized cryosections obtained from these samples to explore the optimum amount of cryoprotectant. Images of cryosectioned bacteria frozen with various levels of cryoprotectant illustrate effects of cryoprotectant concentration. PMID:22077543

  10. Prediction of frozen food properties during freezing using product composition.

    PubMed

    Boonsupthip, W; Heldman, D R

    2007-06-01

    Frozen water fraction (FWF), as a function of temperature, is an important parameter for use in the design of food freezing processes. An FWF-prediction model, based on concentrations and molecular weights of specific product components, has been developed. Published food composition data were used to determine the identity and composition of key components. The model proposed in this investigation had been verified using published experimental FWF data and initial freezing temperature data, and by comparison to outputs from previously published models. It was found that specific food components with significant influence on freezing temperature depression of food products included low molecular weight water-soluble compounds with molality of 50 micromol per 100 g food or higher. Based on an analysis of 200 high-moisture food products, nearly 45% of the experimental initial freezing temperature data were within an absolute difference (AD) of +/- 0.15 degrees C and standard error (SE) of +/- 0.65 degrees C when compared to values predicted by the proposed model. The predicted relationship between temperature and FWF for all analyzed food products provided close agreements with experimental data (+/- 0.06 SE). The proposed model provided similar prediction capability for high- and intermediate-moisture food products. In addition, the proposed model provided statistically better prediction of initial freezing temperature and FWF than previous published models.

  11. 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

  12. 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

  13. 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

  14. Immersion freezing in concentrated solution droplets for a variety of ice nucleating particles

    NASA Astrophysics Data System (ADS)

    Wex, Heike; Kohn, Monika; Grawe, Sarah; Hartmann, Susan; Hellner, Lisa; Herenz, Paul; Welti, Andre; Lohmann, Ulrike; Kanji, Zamin; Stratmann, Frank

    2016-04-01

    The measurement campaign LINC (Leipzig Ice Nucleation counter Comparison) was conducted in September 2015, during which ice nucleation measurements as obtained with the following instruments were compared: - LACIS (Leipzig Aerosol Cloud Interaction Simulator, see e.g. Wex et al., 2014) - PIMCA-PINC (Portable Immersion Mode Cooling Chamber together with PINC) - PINC (Portable Ice Nucleation Chamber, Chou et al., 2011) - SPIN (SPectrometer for Ice Nuclei, Droplet Measurement Technologies) While LACIS and PIMCA-PINC measured immersion freezing, PINC and SPIN varied the super-saturation during the measurements and collected data also for relative humidities below 100% RHw. A suite of different types of ice nucleating particles were examined, where particles were generated from suspensions, subsequently dried and size selected. For the following samples, data for all four instruments are available: K-feldspar, K-feldspar treated with nitric acid, Fluka-kaolinite and birch pollen. Immersion freezing measurements by LACIS and PIMCA-PINC were in excellent agreement. Respective parameterizations from these measurement were used to model the ice nucleation behavior below water vapor saturation, assuming that the process can be described as immersion freezing in concentrated solutions. This is equivalent to simply including a concentration dependent freezing point depression in the immersion freezing parameterization, as introduced for coated kaolinite particles in Wex et al. (2014). Overall, measurements performed below water vapor saturation were reproduced by the model, and it will be discussed in detail, why deviations were observed in some cases. Acknowledgement: Part of this work was funded by the DFG Research Unit FOR 1525 INUIT, grant WE 4722/1-2. Literature: Chou, C., O. Stetzer, E. Weingartner, Z. Juranyi, Z. A. Kanji, and U. Lohmann (2011), Ice nuclei properties within a Saharan dust event at the Jungfraujoch in the Swiss Alps, Atmos. Chem. Phys., 11(10), 4725

  15. 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

  16. 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.

  17. Freezing transition of a strongly dipolar simple fluid

    NASA Astrophysics Data System (ADS)

    Gao, G. T.; Zeng, X. C.

    2000-03-01

    The freezing transition of a strongly dipolar Lennard-Jones fluid is investigated using Monte Carlo simulation. It is found that the system undergoes a ferroelectric liquid-to-solid transition when cooled under a constant pressure. Near the triple point the stable solid phase is a body-centered orthorhombic ferroelectric crystal; a metastable ferroelectric solid phase with distorted hexagonal lattice structure is also discovered. To locate the freezing point, Gibbs free energies of the solid and liquid phase are determined using a thermodynamic integration method.

  18. Freezing injury in potato leaves.

    PubMed

    Sukumaran, N P; Weiser, C J

    1972-11-01

    Time-temperature profiles of freezing leaves from frost-resistant (Solanum acaule Bitt.) and frost-susceptible (Solanum tuberosum L. subsp. tuberosum Hawkes) types of potatoes did not reveal any major differences. The pattern of change in resistance of leaves to low voltage, low frequency current during freezing was different in the frost-resistant and susceptible leaves. In tissue sections from both types of leaves, cells freeze extracellularly at cooling velocities lower than 5 C per minute. Cells from leaves of resistant plants showed a higher osmotic pressure but not a higher water permeability than those from susceptible plants. The extent of injury caused by even very slow freezing was greater than that caused by equivalent isopiestic desiccation, particularly in susceptible leaves. The higher osmotic pressure in cells of leaves from resistant plants can account for the greater desiccation resistance but not for the frost resistance observed. PMID:16658217

  19. [Masked depression].

    PubMed

    Preradović, M; Griva, D; Eror, S

    1991-01-01

    The study comprised 25 patients with masked depression and 30 patients with endogenous depression. According to the general characteristics both groups were homogenous and accordingly, comparable. Together with clinical evaluation of depressive syndrome, psychological management was applied. Rorschach test, Thematic Apperception Test and Minnesota Multiphasic Personality Inventory were used in the study. In the clinical picture of masked depressions somatovegetative disorders dominated and depressive behavior in endogenous depression. The frequence of suicid does not differ between patients with masked and endogenous depression.

  20. 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...

  1. 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...

  2. 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...

  3. 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...

  4. 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...

  5. Intracellular freezing and survival in the freeze tolerant alpine cockroach Celatoblatta quinquemaculata.

    PubMed

    Worland, M R; Wharton, D A; Byars, S G

    2004-01-01

    The alpine cockroach Celatoblatta quinquemaculata is common at altitudes of around 1500 m on the Rock and Pillar range of Central Otago, New Zealand where it experiences freezing conditions in the winter. The cockroach is freeze tolerant, but only to c. -9 degrees C. The cause of death at temperatures below this is unknown but likely to be due to osmotic damage to cells (shrinkage). This study compared the effect of different ice nucleation temperatures (-2 and -4 degrees C) on the viability of three types of cockroach tissue (midgut, Malpighian tubules and fat body cells) and cooling to three different temperatures (-5, -8, -12 degrees C). Two types of observations were made (i) cryomicroscope observations of ice formation and cell shrinkage (ii) cell integrity (viability) using vital stains. Cell viability decreased with lower treatment temperatures but ice nucleation temperature had no significant effect. Cryomicroscope observations showed that ice spread through tissue faster at -4 than -2 degrees C and that intracellular freezing only occurred when nucleated at -4 degrees C. From temperature records during cooling, it was observed that when freezing occurred, latent heat immediately increased the insect's body temperature close to its melting point (c. -0.3 degrees C). This "rebound" temperature was independent of nucleation temperature. Some tissues were more vulnerable to damage than others. As the gut is thought to be the site of freezing, it is significant that this tissue was the most robust. The ecological importance of the effect of nucleation temperature on survival of whole animals under field conditions is discussed.

  6. To freeze or not to freeze? An evolutionary perspective on the cold-hardiness strategies of overwintering ectotherms.

    PubMed

    Voituron, Yann; Mouquet, Nicolas; de Mazancourt, Claire; Clobert, Jean

    2002-08-01

    We address the question of whether freeze-tolerance, freeze-avoidance, or mixed strategy represents the best adaptation for overwintering ectotherms to endure severe winter. To this end, we develop an optimization fitness model that takes into account different physiological parameters such as energetic level, the physiological stress associated with each strategy, and climatic variables. The results show that the freeze-tolerance strategy is strongly dependent on a low sensitivity to the number of freezing days and on a capacity to reduce stress associated with freezing. This strategy is also favored when the initial energetic level is low compared to the freeze-avoidance strategy, which is favored by a high initial energetic level, a low stress associated with the supercooling, and a low sensitivity of this strategy to climatic conditions. From a theoretical point of view, the mixed strategy permits survival in harsher environments but requires the optimization of all parameters involved in both cold-hardiness strategies. However, the mixed strategy shows energetic advantages in variable environments allowing animals to resist the harshest periods. From the model results, it appears that the physiological processes developed by ectotherms to reduce these stresses might be a key to understanding the evolution of the cold-hardiness strategies.

  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

    2015-05-04

    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.

  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. 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

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

    NASA Astrophysics Data System (ADS)

    Marcolli, C.

    2013-06-01

    , 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.

  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. Theoretical analysis of specimen cooling rate during impact freezing and liquid-jet freezing of freeze-etch specimens.

    PubMed

    Kopstad, G; Elgsaeter, A

    1982-11-01

    We have carried out a theoretical analysis of specimen cooling rate under ideal conditions during impact freezing and liquid-jet freezing. The analysis shows that use of liquid helium instead of liquid nitrogen as cooling medium during impact freezing results in an increase in a specimen cooling rate of no more than 30-40%. We have further shown that when both impact freezing and liquid-jet freezing are conducted at liquid nitrogen temperature, the two methods give approximately the same specimen cooling rate under ideal conditions except for a thin outer layer of the specimen. In this region impact freezing yields the highest cooling rate. PMID:7171712

  15. 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.

  16. Water freezing and ice melting

    DOE PAGES

    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

  17. 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.

  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. 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

  20. 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.

  1. Measuring and modeling hemoglobin aggregation below the freezing temperature.

    PubMed

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

    2013-08-01

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

  2. 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

  3. Freezing of fluids confined between mica surfaces.

    PubMed

    Ayappa, K G; Mishra, Ratan K

    2007-12-27

    Using grand ensemble simulations, we show that octamethyl-cyclo-tetra-siloxane (OMCTS) confined between two mica surfaces can form a variety of frozen phases which undergo solid-solid transitions as a function of the separation between the surfaces. For atomically smooth mica surfaces, the following sequence of transitions 1[triangle up] --> 1[triangle up]b --> 2B --> 2 square --> 2[triangle up] are observed in the one- and two-layered regimes, where n[triangle up], n[square], and nB denote triangular, square, and buckled phases, respectively, with the prefix n denoting the number of confined layers. The presence of potassium on mica is seen to have a strong influence on the degree of order induced in the fluid. The sequence of solid-solid transitions that occurs with the smooth mica surface is no longer observed. When equilibrated with a state point near the liquid-solid transition, a counterintuitive freezing scenario is observed in the presence of potassium. Potassium disrupts in-plane ordering in the fluid in contact with the mica surface, and freezing is observed only in the inner confined layers. The largest mica separations at which frozen phases were observed ranged from separations that could accommodate six to seven fluid layers. The extent of freezing and the square-to-triangular lattice transition was found to be sensitive to the presence of potassium as well as the thermodynamic conditions of the bulk fluid. The implications of our results on interpretation of surface force experiments as well as the generic phase behavior of confined soft spheres is discussed. PMID:18092763

  4. 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).

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

    SciTech Connect

    Bevel, A.; Hrudey, S.; Dudas, M.; Sego, D.

    1996-11-01

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

  6. Mechanism of freeze-thaw instability of aluminum hydroxycarbonate and magnesium hydroxide gels.

    PubMed

    Zapata, M I; Feldkamp, J R; Peck, G E; White, J L; Hem, S L

    1984-01-01

    The effect of freeze-thaw cycles on the physical stability of aluminum hydroxycarbonate and magnesium hydroxide gels was studied. Coagulation following a freeze-thaw cycle, leading to the formation of visible aggregates, affected the content uniformity of both gels. The freeze-thaw cycles did not affect the crystal form or surface characteristics of the gels as determined by X-ray powder diffraction and point of zero charge, but caused a slight reduction in the rate of acid neutralization and a large increase in the rate of sedimentation. The greatest effect was observed after the first freeze-thaw cycle. While the duration of freezing was not a factor, the rate of freezing was important and was inversely related to the aggregate size. The aggregates which formed following a freeze-thaw cycle were not redispersed by shaking, but were reversed by ultrasonic treatment or homogenization. The adsorption of polymers or surface-active agents prior to freezing reduced and, in some cases, prevented the formation of aggregates. The physical instability produced by a freeze-thaw cycle was explained by the modified DLVO theory. The force exerted on the particles by the growing ice crystals forced the particles into the primary minimum, producing strong interparticle attraction. On thawing, simple agitation did not provide enough force to overcome the attractive force of the primary minimum. Adsorption of polymers or surface-active agents increased the steric repulsive force and prevented the particles from reaching the primary minimum. PMID:6694078

  7. 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.

  8. 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.

  9. 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.

  10. Adolescent depression: a metasynthesis.

    PubMed

    Dundon, Edith Emma

    2006-01-01

    Concerns about the adequate assessment and treatment of adolescent depression have been in the forefront of pediatric mental health literature in the recent past. While quantitative studies have provided valuable information, the voice of the adolescent has been lacking in the development of theory and treatment of this prevalent disorder. Using approach, a metasynthesis of six qualitative studies was conducted. This process revealed six themes that outline the course of adolescents who struggle with depression: (a) beyond the blues, (b) spiraling down and within, (c) breaking points, (d) seeing and being seen, (e) seeking solutions, and (f) taking control. Knowledge of the experience of adolescent depression will aid practitioners in recognition and early intervention for the increasing number of adolescents suffering with depression, as well as guide educational initiatives to provide needed information on the symptoms of depression and available resources for getting help.

  11. [Severe depression : psychoanalysis].

    PubMed

    Bouvet de la Maisonneuve, O

    2009-12-01

    The indication for psychoanalysis in severe depression is not clear. And yet, demands for this type of intervention are increasing, despite the absence of any form of consensus on the subject. Freud considered depression as a failure of analytical efforts and, based on this observation, revised his theory, in particular to include the notions of narcissism and the death drive. Many analysts have been reluctant to follow his teachings on this last point and provide depressed patients with analytical-type therapies aimed at restoring narcissism. Melanie Klein pushed Freud's ideas about depression even further and brought such therapies back to the heart of analytical practice. Jacques Lacan took the debate to another level by proposing an overhaul of the principles on which analysis has been based. Today, while following certain precautionary rules, true psychoanalyses can be proposed to patients with severe depression, whether of the bipolar, recurring or even neurotic type that can reach this level of severity.

  12. [Severe depression : psychoanalysis].

    PubMed

    Bouvet de la Maisonneuve, O

    2009-12-01

    The indication for psychoanalysis in severe depression is not clear. And yet, demands for this type of intervention are increasing, despite the absence of any form of consensus on the subject. Freud considered depression as a failure of analytical efforts and, based on this observation, revised his theory, in particular to include the notions of narcissism and the death drive. Many analysts have been reluctant to follow his teachings on this last point and provide depressed patients with analytical-type therapies aimed at restoring narcissism. Melanie Klein pushed Freud's ideas about depression even further and brought such therapies back to the heart of analytical practice. Jacques Lacan took the debate to another level by proposing an overhaul of the principles on which analysis has been based. Today, while following certain precautionary rules, true psychoanalyses can be proposed to patients with severe depression, whether of the bipolar, recurring or even neurotic type that can reach this level of severity. PMID:20141799

  13. 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... outside of liquid egg containers shall be clean and free from evidence of liquid egg. (e) Frozen...

  14. 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...

  15. 9 CFR 590.534 - Freezing facilities.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Freezing facilities. 590.534 Section 590.534 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG..., and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off...

  16. 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 590.536 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean...

  17. 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.

  18. 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.

  19. The unsuitability of meteoritic and other nuclei for polar stratospheric cloud freezing

    NASA Astrophysics Data System (ADS)

    Biermann, U. M.; Presper, T.; Koop, T.; Mößinger, J.; Crutzen, P. J.; Peter, Th.

    Bulk freezing experiments have been performed with binary and ternary HNO3/H2SO4/H2O solutions containing original micrometeorites, ground samples of representative larger meteorites and other freezing nuclei of potential stratospheric importance. The experiments enable us to determine upper bounds for the heterogeneous freezing rates of sulfuric and nitric acid hydrates. Based on an analysis of the meteoritic mass flux from space and of the modifications meteorites undergo when entering the atmosphere, the resulting morphology and surface area of extraterrestrial material in the stratosphere are estimated. From this micrometeorites gained from Antarctica are shown to be a good proxy for meteoritic surfaces in the stratosphere. In combination with this analysis the freezing experiments suggest that heterogeneous nucleation rates on micrometeorites are too low to enhance freezing of polar stratospheric clouds above the frost point.

  20. Assessment of molten-salt solar central-receiver freeze-up and recovery events

    SciTech Connect

    Pacheco, J.E.; Dunkin, S.R.

    1996-02-01

    Molten salt used as a heat transfer fluid in central-receiver so ar power plants has a high freezing point (430{degrees}F (221{degrees}C)). It is very likely during the life of the plant that the receiver will accidentally freeze up due to equipment malfunction or operator error. Experiments were conducted to measure the effects of a molten salt receiver freeze-up and recovery event and methods to thaw the receiver. In addition, simulated freeze/thaw experiments were conducted to determine what happens when salt freezes and is thawed in receiver tubes and to quantify the damage caused to candidate receiver tube materials. Fourteen tube samples of various materials, diameters and wall thicknesses were tested to destruction. Results of these tests are presented in this paper.

  1. 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.

  2. 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)

  3. 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

  4. 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

  5. Teen Depression

    MedlinePlus

    ... shown that certain types of talk therapy or psychotherapy can help teens deal with depression. These include ... behaviors, and feelings related to depression, and interpersonal psychotherapy, which focuses on working on relationships. Read more ...

  6. 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 ...

  7. 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.

  8. 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.

  9. 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

  10. 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…

  11. 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

  12. Nanocrystal Formation under Confinement in a Rubbery Polymer: Large Melting Point Depression in Telechelic, Pyrene-End-Labeled PDMS as a Function of PDMS Molecular Weight

    NASA Astrophysics Data System (ADS)

    Jones, Bryce; Torkelson, John

    2003-03-01

    The associative behavior of telechelic, pyrene-end-labeled PDMS (Py-PDMS-Py) has been studied by excimer fluorescence and thermal analysis. In 24k g/mol Py-PDMS-PY, there is significant agglomeration of pyrenyl labels as evidenced by a high excimer to monomer intensity ratio, the presence of ground-state dimers or aggregates observed via excitation spectra, and substantial modificiation of rheology. In 5k g/mol Py-PDMS-Py there is a higher aggomeration level that evolves substantially with time in films prepared from solution, eventually yielding pyrenyl nanocrystals with a melting temperature (Tm) of 40C, representing a 90C depression of Tm relative to that of bulk pyrenyl dye. Cooling the 24k g/mol Py-PDMS-Py to -70C for an extended period yields a Tm of -40C, indicative of much reduced nanocrystal size relative to that in the 5k g/mol Py-PDMS-Py. Progress in understanding the relationships of molecular weight and confinement in ultrathin films to nanocrystal vs. agglomerate/aggregate formation as well as the level of nanocrystal vs. agglomerate formation to gelation will be discussed.

  13. Hunters Point Redeveloped: A Sixth-Grade Venture. A Tape Transcription of Sixth Graders Discussing Their Plan for Redeveloping a Depressed Area in San Francisco.

    ERIC Educational Resources Information Center

    Leeper, Robert, R., Ed.; O'Neill, Mary A., Ed.

    A class composed of many minority group children in a low socio-economic area school some distance from Hunters Point, developed this Proposal in a self-created social studies unit. The children and their teacher had been motivated by a summer crisis which had the city in a turmoil. They decided to investigate what could be done to improve the…

  14. 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

  15. Ellipsometric characterization of surface freezing in Ga-based alloys

    NASA Astrophysics Data System (ADS)

    Bartel, K.; Nattland, D.; Kumar, A.; Dogel, S.; Freyland, W.

    2006-04-01

    We present results on surface freezing of Ga-based alloys, GaBi, GaPb and GaTl, above the liquidus line between the Ga-rich eutectic and the monotectic point. Spectroscopic ellipsometry (0.8 eV <=hν<=4.2 eV) and kinetic single wavelength ellipsometry (2.75 eV) have been employed to probe the changes of the interfacial electronic structures on surface freezing. To minimize thermal gradients across the sample a heatable cap that covers the sample and crucible was developed. The surface freezing temperature, TSF, for the spontaneous formation of a solid-like film on top of the Ga-rich liquid on cooling the sample from the homogeneous phase region was found to be independent of the temperature difference between the upper and lower furnace (ΔT: +10 to -10 K) and only weakly dependent on the cooling rate (\\partial T/\\partial t : 2.5-20 K h-1). In the case of GaPb the solid film consists of solid Pb with a thickness h>=400 Å. Comparing with GaBi we draw analogous conclusions for GaPb and GaTl and suggest that the surface freezing transition precedes the bulk phase transition along the liquidus line as the alloy is cooled.

  16. Survival of freezing by free-living Antarctic soil nematodes.

    PubMed

    Convey, P; Worland, M R

    2000-01-01

    Free-living microbivorous nematodes become numerically dominant in Antarctic terrestrial faunas as environmental conditions become more severe, while also reaching very high levels of abundance in moist, vegetated habitats. Nematodes have little resistance to freezing via exogenous ice nucleation, such as would occur as their microhabitat freezes. We report the results of experiments testing the ability of seven maritime Antarctic nematode taxa to survive freezing in small water droplets at high sub-zero temperatures. Isolated individuals of these species possessed supercooling characteristics similar to those previously reported (supercooling points -6 to -25 degree C). When frozen in water at -3 to -6 degree C, most showed high (> 70%) survival both (i) after rapid cooling (1 degree C/min) to c. -60 degree C followed by immediate rewarming, and (ii) when held for 7-12 h at either -10 or -30 degree C, although the proportions surviving varied between species. We propose that the ability to survive freezing while fully hydrated at high sub-zero temperatures is one of the most important aspects of these species' survival tactics.

  17. [Melancholia and neurotic depression].

    PubMed

    Hartmann, S

    1999-11-01

    The author considers the psychopathological distinction between endogenous and neurotic depression as one of differing psychodynamics. In so doing he embeds both illnesses within psychoanalytic theory while at the same time allowing a sharp differentiation. Even the premorbid personalities of patients with endogenous and neurotic depression are different. The personalities of those with endogenous depression bear a similarity to those with obsessional character and betray a pathological super-ego monopolized by defence mechanisms. The personalities of patients with neurotic depression show an oral-dependent structure characterised by a structural deficit of the ego functions and of an autonomous super-ego. These factors are responsible for the greatly differing pathodynamics found in these illnesses and point to different etiological factors in socialization. PMID:10593139

  18. The initial freezing temperature of foods at high pressure.

    PubMed

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

    2008-04-01

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

  19. Characteristics of sugar surfactants in stabilizing proteins during freeze-thawing and freeze-drying.

    PubMed

    Imamura, Koreyoshi; Murai, Katsuyuki; Korehisa, Tamayo; Shimizu, Noriyuki; Yamahira, Ryo; Matsuura, Tsutashi; Tada, Hiroko; Imanaka, Hiroyuki; Ishida, Naoyuki; Nakanishi, Kazuhiro

    2014-06-01

    Sugar surfactants with different alkyl chain lengths and sugar head groups were compared for their protein-stabilizing effect during freeze-thawing and freeze-drying. Six enzymes, different in terms of tolerance against inactivation because of freeze-thawing and freeze-drying, were used as model proteins. The enzyme activities that remained after freeze-thawing and freeze-drying in the presence of a sugar surfactant were measured for different types and concentrations of sugar surfactants. Sugar surfactants stabilized all of the tested enzymes both during freeze-thawing and freeze-drying, and a one or two order higher amount of added sugar surfactant was required for achieving protein stabilization during freeze-drying than for the cryoprotection. The comprehensive comparison showed that the C10-C12 esters of sucrose or trehalose were the most effective through the freeze-drying process: the remaining enzyme activities after freeze-thawing and freeze-drying increased at the sugar ester concentrations of 1-10 and 10-100 μM, respectively, and increased to a greater extent than for the other surfactants at higher concentrations. Results also indicate that, when a decent amount of sugar was also added, the protein-stabilizing effect of a small amount of sugar ester through the freeze-drying process could be enhanced.

  20. 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.

  1. Contact Freezing of Water by Salts.

    PubMed

    Niehaus, Joseph; Cantrell, Will

    2015-09-01

    Water is unlikely to crystallize homogeneously at temperatures greater than -34 °C. Freezing at higher temperatures is heterogeneous-catalyzed by the presence of a second substance. If that substance is at an air-water interface, then the mode is called contact freezing, and it typically will trigger nucleation at a higher temperature than if the substance were wholly immersed within the liquid. We find that the impact of salt particles initiates freezing in experiments using water droplets at supercoolings of 9 to 16 °C. These results show that contact freezing nuclei need not be effective as immersion mode nuclei. We discuss our results in the context of proposed mechanisms of contact freezing. Finally, we use the time scales for diffusion of heat and of ions and the propagation of a sound wave through the droplet to estimate that contact freezing occurs within 10 ns of impact. PMID:26291340

  2. 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

  3. 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...

  4. Mechanism of freeze-drying drug nanosuspensions.

    PubMed

    Chung, Nae-Oh; Lee, Min Kyung; Lee, Jonghwi

    2012-11-01

    Drug nanoparticles prepared in a liquid medium are commonly freeze-dried for the preparation of an oral dosage in solid dosage form. The freezing rate is known to be a critical parameter for redispersible nanoformulations. However, there has been controversy as to whether a fast or slow freezing rate prevents irreversible aggregation. A systematic investigation is presented herein regarding the effect of both the molecular weight of the cryoprotectant and the freezing rate in order to elucidate the mechanism underlying irreversible aggregation. It was found that irreversible aggregation occurred during drying rather than freezing, although a proper freezing rate is critical. A more homogeneous distribution of the cryoprotectant and drug nanoparticles led to more redispersible powders. Thus, keeping the local concentration distribution of the nanoparticles and cryoprotectant fixed during the freezing step plays a critical role in how the freezing rate affects the redispersibility. The kinetic approach of excluding the tendency of ice crystal growth permitted an explanation of the controversial results. This study will facilitate an in-depth understanding of the aggregation process of nanoparticles or proteins during freeze-drying.

  5. Scanning electron microscopy of muscle myofibrils after high pressure freezing and freeze-substitution-staining.

    PubMed

    Malecki, M; Greaser, M L

    1993-03-01

    A novel approach to study the three dimensional ultrastructure of organelles and cells by means of scanning electron microscopy is described. Muscle myofibrils have been used in the development of the techniques since their structure is well characterized using conventional electron microscopic methods. Myofibrils in rigor buffer (with no cryo-protectants or pressure sealants) were frozen at high pressure (2300 bar) within specially designed chambers. The frozen specimens were then freeze-substituted-stained with methanol containing tungsten and iron salts and finally critical point dried. These methods allowed scanning electron microscopic observations of the organization of individual filaments within whole myofibrils over several sarcomeres. Images obtained showed excellent structural preservation with three dimensional information which is not available with other electron microscopic techniques. Success in these approaches was ascribed to (a) rapid and uniform freezing at high pressure without ice segregation patterns, (b) uniform electro-conductivity of the specimen closely attached to the polished carbon piston/carrier, and (c) good electron emission (secondary and back-scattered) from the metal incorporated into the myofibril structure without additional coating. PMID:7686303

  6. Freezing resistance of antifreeze-deficient larval Antarctic fish.

    PubMed

    Cziko, Paul A; Evans, Clive W; Cheng, Chi-Hing C; DeVries, Arthur L

    2006-02-01

    Antarctic notothenioids, along with many other polar marine fishes, have evolved biological antifreeze proteins (AFPs) to survive in their icy environments. The larvae of Antarctic notothenioid fish hatch into the same frigid environment inhabited by the adults, suggesting that they must also be protected by sufficient AFPs, but this has never been verified. We have determined the contribution of AFPs to the freezing resistance of the larvae of three species: Gymnodraco acuticeps, Pagothenia borchgrevinki and Pleuragramma antarcticum. Of the three, only P. borchgrevinki larvae are protected by high, adult levels of AFPs. Hatchling G. acuticeps and P. antarcticum have drastically inadequate AFP concentrations to avoid freezing at the ambient seawater temperature (-1.91 degrees C). We raised G. acuticeps larvae and measured the AFP levels in their blood for approximately 5 months post hatching. Larval serum freezing point was -1.34+/-0.04 degrees C at the time of hatch; it began to decrease only after 30 days post hatch (d.p.h.), and finally reached the adult value (-2.61+/-0.03 degrees C) by 147 d.p.h. Additionally, AFP concentrations in their intestinal fluids were very low at hatching, and did not increase with age throughout a sampling period of 84 d.p.h. Surviving in a freezing environment without adequate AFP protection suggests that other mechanisms of larval freezing resistance exist. Accordingly, we found that G. acuticeps hatchlings survived to -3.6+/-0.1 degrees C while in contact with external ice, but only survived to -1.5+/-0.0 degrees C when ice was artificially introduced into their tissues. P. antarcticum larvae were similarly resistant to organismal freezing. The gills of all three species were found to be underdeveloped at the time of hatch, minimizing the risk of ice introduction through these delicate structures. Thus, an intact integument, underdeveloped gill structures and other physical barriers to ice propagation may contribute significantly

  7. [Atypical depression].

    PubMed

    Escande, M; Boucard, J

    1999-04-01

    The principal atypical aspects of depressive disease are: minor and attenued aspects, monosymptomatic and atypical aspects (food disorders and sleep disorders), masqued aspects (somatoform, anxious, characterial and addict disorders), atypical aspects of child (anxious nevrotical disorder), pseudo-demented and characterial aspects of aged subjects. Facing to these aspects, the diagnosis of depression is evoqued on: the recent and fast advent of these disorders, their morning predominance, their recurrent character, the state of attenued depressive symptoms (anhedonia), the positive responsiveness to treatment.

  8. 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.

  9. 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

  10. 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.

  11. Freeze tolerance and avoidance in plants

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold acclimation is a multigenic, quantitative trait that involves biochemical and structural changes that effect the physiology of a plant. Mechanisms associated with freeze tolerance or freeze avoidance develop and are lost on an annual cycle. When conducting studies to characterize and determin...

  12. Freezing: an underutilized food safety technology?

    PubMed

    Archer, Douglas L

    2004-01-15

    Freezing is an ancient technology for preserving foods. Freezing halts the activities of spoilage microorganisms in and on foods and can preserve some microorganisms for long periods of time. Frozen foods have an excellent overall safety record. The few outbreaks of food-borne illness associated with frozen foods indicate that some, but not all human pathogens are killed by commercial freezing processes. Freezing kills microorganisms by physical and chemical effects and possibly through induced genetic changes. Research is needed to better understand the physical and chemical interactions of various food matrices with the microbial cell during freezing and holding at frozen temperatures. The literature suggests that many pathogenic microorganisms may be sublethally injured by freezing, so research should be done to determine how to prevent injured cells from resuscitating and becoming infectious. Studies on the genetics of microbial stress suggest that the induction of resistance to specific stresses may be counteracted by, for example, simple chemicals. Research is needed to better understand how resistance to the lethal effect of freezing is induced in human pathogens and means by which it can be counteracted in specific foods. Through research, it seems possible that freezing may in the future be used to reliably reduce populations of food-borne pathogens as well as to preserve foods.

  13. Freezing kinetics in overcompressed water

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

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

  14. 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.

  15. Directional freezing of spermatozoa and embryos.

    PubMed

    Arav, Amir; Saragusty, Joseph

    2013-01-01

    Directional freezing is based on a simple thermodynamic principle whereby the sample is moved through a predetermined temperature gradient at a velocity that determines the cooling rate. Directional freezing permits a precise and uniform cooling rate in small- and large-volume samples. It avoids supercooling and reduces mechanical damage caused by crystallisation. Directional solidification was used to date for slow and rapid freezing, as well as for vitrification of oocytes and embryos by means of the minimum drop size technique: small drops are placed on a microscope slide that is moved at high velocity from the hot base to the cold base. Sperm samples from a wide range of domestic and wild animals were successfully cryopreserved using the directional freezing method. The bovine sexed semen industry may benefit from the increased survival of spermatozoa after directional freezing.

  16. 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.

  17. 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

  18. Metacognition and depressive realism: evidence for the level-of-depression account.

    PubMed

    Soderstrom, Nicholas C; Davalos, Deana B; Vázquez, Susana M

    2011-09-01

    Introduction. The present study examined the relationship between metacognition (i.e., "thinking about thinking") and depression. More specifically, the depressive realism hypothesis (Alloy & Abramson, 1979), which posits that depressed people have a more accurate view of reality than nondepressed people, was tested. Methods. Nondepressed, mildly depressed, and moderately depressed individuals predicted their memory performance by making judgements of learning after each studied item. These predictions were then compared with actual performance on a free recall task to assess calibration, an index of metacognitive accuracy. Results and conclusions. Consistent with the depressive realism hypothesis, mild depression was associated with better calibration than nondepression. However, this "sadder but wiser" phenomenon appears to only exist to point, as moderate depression and nondepression showed no calibration differences. Thus, the level-of-depression account of depressive realism is supported.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Drought increases the freezing resistance of high-elevation plants of the Central Chilean Andes.

    PubMed

    Sierra-Almeida, Angela; Reyes-Bahamonde, Claudia; Cavieres, Lohengrin A

    2016-08-01

    Freezing temperatures and summer droughts shape plant life in Mediterranean high-elevation habitats. Thus, the impacts of climate change on plant survival for these species could be quite different to those from mesic mountains. We exposed 12 alpine species to experimental irrigation and warming in the Central Chilean Andes to assess whether irrigation decreases freezing resistance, irrigation influences freezing resistance when plants are exposed to warming, and to assess the relative importance of irrigation and temperature in controlling plant freezing resistance. Freezing resistance was determined as the freezing temperature that produced 50 % photoinactivation [lethal temperature (LT50)] and the freezing point (FP). In seven out of 12 high-Andean species, LT50 of drought-exposed plants was on average 3.5 K lower than that of irrigated plants. In contrast, most species did not show differences in FP. Warming changed the effect of irrigation on LT50. Depending on species, warming was found to have (1) no effect, (2) to increase, or (3) to decrease the irrigation effect on LT50. However, the effect size of irrigation on LT50 was greater than that of warming for almost all species. The effect of irrigation on FP was slightly changed by warming and was sometimes in disagreement with LT50 responses. Our data show that drought increases the freezing resistance of high-Andean plant species as a general plant response. Although freezing resistance increases depended on species-specific traits, our results show that warmer and moister growing seasons due to climate change will seriously threaten plant survival and persistence of these and other alpine species in dry mountains.

  5. Drought increases the freezing resistance of high-elevation plants of the Central Chilean Andes.

    PubMed

    Sierra-Almeida, Angela; Reyes-Bahamonde, Claudia; Cavieres, Lohengrin A

    2016-08-01

    Freezing temperatures and summer droughts shape plant life in Mediterranean high-elevation habitats. Thus, the impacts of climate change on plant survival for these species could be quite different to those from mesic mountains. We exposed 12 alpine species to experimental irrigation and warming in the Central Chilean Andes to assess whether irrigation decreases freezing resistance, irrigation influences freezing resistance when plants are exposed to warming, and to assess the relative importance of irrigation and temperature in controlling plant freezing resistance. Freezing resistance was determined as the freezing temperature that produced 50 % photoinactivation [lethal temperature (LT50)] and the freezing point (FP). In seven out of 12 high-Andean species, LT50 of drought-exposed plants was on average 3.5 K lower than that of irrigated plants. In contrast, most species did not show differences in FP. Warming changed the effect of irrigation on LT50. Depending on species, warming was found to have (1) no effect, (2) to increase, or (3) to decrease the irrigation effect on LT50. However, the effect size of irrigation on LT50 was greater than that of warming for almost all species. The effect of irrigation on FP was slightly changed by warming and was sometimes in disagreement with LT50 responses. Our data show that drought increases the freezing resistance of high-Andean plant species as a general plant response. Although freezing resistance increases depended on species-specific traits, our results show that warmer and moister growing seasons due to climate change will seriously threaten plant survival and persistence of these and other alpine species in dry mountains. PMID:27053321

  6. Physical state of L-histidine after freeze-drying and long-term storage.

    PubMed

    Osterberg, T; Wadsten, T

    1999-08-01

    Liquid samples of L-histidine of varying pH values and mixed with salt, metal ions, polysorbate 80 and sucrose have been analysed by differential scanning calorimetry to evaluate the influence of these additives on the glass transition temperature and crystallisation of L-histidine during freezing and thawing. L-Histidine solutions of varying pH were freeze-dried with and without a thermal cycle and the physical state of the freeze-dried cakes, following long-term storage, were studied by powder X-ray diffraction. Amorphous L-histidine crystallised when it was exposed to moisture, and the identity of the crystalline materials is reported. The crystallisation of L-histidine during freezing and thawing is dependent on the pH of the solution and is shown to be at a minimum at pH 6, which coincides with the pK(a) of the imidazoline function. Sucrose inhibited the crystallisation of L-histidine during thawing, while sodium chloride or polysorbate 80 did not. The addition of metal ions (Ca2+ and Mg2+) up to 10% (w/w) did not depress the glass transition temperature significantly, while the addition of Zn2+ increased it. The physical state of L-histidine after freeze-drying is shown to be dependent on both the pH of the solution and the freezing cycle. The risk of crystallisation of amorphous L-histidine is low if the freeze-dried material is protected from moisture. PMID:10425380

  7. Dynamics of a model colloidal suspension from dilute to freezing.

    PubMed

    Hannam, S D W; Daivis, P J; Bryant, G

    2016-07-01

    Molecular dynamics simulation was used to study a model colloidal suspension at a range of packing fractions from the dilute limit up to the freezing point. This study builds on previous work by the authors which modeled the colloidal particles with a hard core surrounded by a Weeks-Chandler-Anderson potential with modified interaction parameters, and included an explicit solvent. In this work, we study dynamical properties of the model by first calculating the velocity autocorrelation function, the self-diffusion coefficient, and the mutual diffusion coefficient. We also perform detailed calculations of the colloidal particle intermediate scattering function to study the change in dynamics leading up to the freezing point, and to determine whether the current model can be used to interpret light scattering experiments. We then perform a multiexponential analysis on the intermediate scattering function results and find that the data are fitted well by the sum of two exponentials, which is in line with previous analysis of experimental colloidal suspensions. The amplitudes and decay coefficients of the two modes are determined over a large range of wave vectors at packing fractions leading up to the freezing point. We found that the maximum wave vector at which macroscopic diffusive behavior was observed decreased as the packing fraction increased, and a simple extrapolation shows the maximum wave vector going to zero at the melting point. Lastly, the ratio of the two decay coefficients is compared to the scaling law proposed by Segrè and Pusey [Phys. Rev. Lett. 77, 771 (1996)PRLTAO0031-900710.1103/PhysRevLett.77.771]. It was found that the ratio was not constant, but instead was wave vector dependent. PMID:27575191

  8. Dynamics of a model colloidal suspension from dilute to freezing

    NASA Astrophysics Data System (ADS)

    Hannam, S. D. W.; Daivis, P. J.; Bryant, G.

    2016-07-01

    Molecular dynamics simulation was used to study a model colloidal suspension at a range of packing fractions from the dilute limit up to the freezing point. This study builds on previous work by the authors which modeled the colloidal particles with a hard core surrounded by a Weeks-Chandler-Anderson potential with modified interaction parameters, and included an explicit solvent. In this work, we study dynamical properties of the model by first calculating the velocity autocorrelation function, the self-diffusion coefficient, and the mutual diffusion coefficient. We also perform detailed calculations of the colloidal particle intermediate scattering function to study the change in dynamics leading up to the freezing point, and to determine whether the current model can be used to interpret light scattering experiments. We then perform a multiexponential analysis on the intermediate scattering function results and find that the data are fitted well by the sum of two exponentials, which is in line with previous analysis of experimental colloidal suspensions. The amplitudes and decay coefficients of the two modes are determined over a large range of wave vectors at packing fractions leading up to the freezing point. We found that the maximum wave vector at which macroscopic diffusive behavior was observed decreased as the packing fraction increased, and a simple extrapolation shows the maximum wave vector going to zero at the melting point. Lastly, the ratio of the two decay coefficients is compared to the scaling law proposed by Segrè and Pusey [Phys. Rev. Lett. 77, 771 (1996), 10.1103/PhysRevLett.77.771]. It was found that the ratio was not constant, but instead was wave vector dependent.

  9. Dynamics of a model colloidal suspension from dilute to freezing.

    PubMed

    Hannam, S D W; Daivis, P J; Bryant, G

    2016-07-01

    Molecular dynamics simulation was used to study a model colloidal suspension at a range of packing fractions from the dilute limit up to the freezing point. This study builds on previous work by the authors which modeled the colloidal particles with a hard core surrounded by a Weeks-Chandler-Anderson potential with modified interaction parameters, and included an explicit solvent. In this work, we study dynamical properties of the model by first calculating the velocity autocorrelation function, the self-diffusion coefficient, and the mutual diffusion coefficient. We also perform detailed calculations of the colloidal particle intermediate scattering function to study the change in dynamics leading up to the freezing point, and to determine whether the current model can be used to interpret light scattering experiments. We then perform a multiexponential analysis on the intermediate scattering function results and find that the data are fitted well by the sum of two exponentials, which is in line with previous analysis of experimental colloidal suspensions. The amplitudes and decay coefficients of the two modes are determined over a large range of wave vectors at packing fractions leading up to the freezing point. We found that the maximum wave vector at which macroscopic diffusive behavior was observed decreased as the packing fraction increased, and a simple extrapolation shows the maximum wave vector going to zero at the melting point. Lastly, the ratio of the two decay coefficients is compared to the scaling law proposed by Segrè and Pusey [Phys. Rev. Lett. 77, 771 (1996)PRLTAO0031-900710.1103/PhysRevLett.77.771]. It was found that the ratio was not constant, but instead was wave vector dependent.

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

    PubMed

    Grayson, A L; King, D A; Shackelford, S D; Koohmaraie, M; Wheeler, T L

    2014-06-01

    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) were obtained from U.S. Select carcasses classified at the grading stand by the U.S. Meat Animal Research Center visible and near-infrared spectroscopy tenderness system to have predicted slice shear force greater than 16.5 kg at 14 d postmortem. At 2 d postmortem, 2.54 cm thick steaks were cut from each muscle and assigned to 1 of the following treatments: 2 d fresh (2FRESH), 2 d freeze + thaw (2FREEZE), 2 d freeze + thaw + 12 d age (2FREEZE+12AGE), 14 d fresh (14FRESH), 14 d freeze + thaw (14FREEZE), 14 d freeze + thaw + 14 d age (14FREEZE+14AGE), and 28 d fresh (28FRESH). Steaks assigned to a freezing treatment were frozen at -26°C for 30 d before thawing/cooking or thawing with an additional aging period at 2°C. Slice shear force for LL and ST was lower (P < 0.01) for 2FREEZE (27.4 and 24.5 kg) and 14FREEZE (22.4 and 22.4 kg) compared to 2FRESH (33.0 and 29.2 kg) and 14FRESH (25.3 and 25.5 kg), respectively. Slice shear force for LL and ST was lower (P < 0.01) for 2FREEZE+12AGE (17.8 and 20.8 kg) and 14FREEZE+14AGE (14.6 and 19.0 kg) compared to 14FRESH (25.3 and 25.5 kg) and 28FRESH (18.7 and 21.7 kg), respectively. Desmin degradation for LL was not different (P > 0.05) between 2FREEZE (21.0%) and 2FRESH (14.6%) or between 14FREEZE (40.4%) and 14FRESH (38.4%); however, desmin degradation was higher (P < 0.06) in 2FREEZE+12AGE (46.7%) and 14FREEZE+14AGE (71.1%) when compared to 14FRESH (38.4%) and 28FRESH (60.5%), respectively. Cooking loss for LL was higher (P < 0.01) in 2FREEZE+12AGE (15.2%) compared to 14FRESH (14.0%) but was not different (P > 0.05) between 14FREEZE+14AGE (15.0%) and 28FRESH (14.3%). Freezing and thawing or a combination of freezing, thawing

  11. Kinetics of osmotic water flow across cell membranes in non-ideal solutions during freezing and thawing.

    PubMed

    Weng, Lindong; Li, Weizhong; Zuo, Jianguo

    2010-10-01

    Cryopreservation requires quantitatively analytical models to simulate the biophysical responses of biomaterials during cryopreservation. The Mazur model and other improved ones, such as Karlsson model concerning solutions containing cryoprotectants (CPA), are somehow precluded by some minor points, particularly, the assumption of ideal solutions. To avoid the ideal solution assumption, in this study a new method is developed to simulate water transport across cell membranes in non-ideal solutions during cooling and thawing. The comparison between osmolalities calculated by the linear freezing-point depression used in this new method and other non-ideal ones is conducted and a good agreement is achieved. In addition, in an ideal case, besides a theoretical agreement, this new approach has been validated by its numerical simulation results. Comparisons between this new approach and the traditional ones with an ideal solution assumption have been conducted based on a spherical hypothetical cell. The main results are (1) the predicted non-ideal intracellular water content is larger than the ideal results; (2) the concentration of CPA solutions is directly proportional to the deviation between the non-ideal and ideal curves. In the end, this study presents a direct description of the degree of subcooling of the protoplasm during dynamic cooling. This study demonstrates that our experimental data-based method is a valid one with clear physical interpretations, convenient expressions and a more extensive application room than traditional ones. PMID:20654609

  12. Kinetics of osmotic water flow across cell membranes in non-ideal solutions during freezing and thawing.

    PubMed

    Weng, Lindong; Li, Weizhong; Zuo, Jianguo

    2010-10-01

    Cryopreservation requires quantitatively analytical models to simulate the biophysical responses of biomaterials during cryopreservation. The Mazur model and other improved ones, such as Karlsson model concerning solutions containing cryoprotectants (CPA), are somehow precluded by some minor points, particularly, the assumption of ideal solutions. To avoid the ideal solution assumption, in this study a new method is developed to simulate water transport across cell membranes in non-ideal solutions during cooling and thawing. The comparison between osmolalities calculated by the linear freezing-point depression used in this new method and other non-ideal ones is conducted and a good agreement is achieved. In addition, in an ideal case, besides a theoretical agreement, this new approach has been validated by its numerical simulation results. Comparisons between this new approach and the traditional ones with an ideal solution assumption have been conducted based on a spherical hypothetical cell. The main results are (1) the predicted non-ideal intracellular water content is larger than the ideal results; (2) the concentration of CPA solutions is directly proportional to the deviation between the non-ideal and ideal curves. In the end, this study presents a direct description of the degree of subcooling of the protoplasm during dynamic cooling. This study demonstrates that our experimental data-based method is a valid one with clear physical interpretations, convenient expressions and a more extensive application room than traditional ones.

  13. Depressive symptoms and cognitive performance in older adults.

    PubMed

    Shimada, Hiroyuki; Park, Hyuntae; Makizako, Hyuma; Doi, Takehiko; Lee, Sangyoon; Suzuki, Takao

    2014-10-01

    Many longitudinal studies have found that older adults with depressive symptoms or depression have increased risk of cognitive impairment. We investigated the relationships between depressive symptoms or depression, cognitive function, serum brain-derived neurotrophic factor (BDNF), and volumetric MRI measurements in older adults. A total of 4352 individuals aged 65 years or older (mean age 72 years) participated in the study. We investigated medical history and geriatric depression scale-15 (GDS-15) items to determine depression and depressive symptoms. Cognitive tests included the mini-mental state examination (MMSE), story memory, word list memory, trail-making tests, and the symbol digit substitution task. Of the 4352 participants, 570 (13%) fulfilled the criteria for depressive symptoms (GDS-15: 6 + points) and 87 (2%) were diagnosed with depression. All cognitive tests showed significant differences between the 'no depressive symptoms', 'depressive symptoms', and 'depression' groups. The 'depressive symptoms' and 'depression' groups showed lower serum BDNF (p < 0.001) concentrations than the 'no depressive symptoms' group. The 'depressive symptoms' group exhibited greater atrophy of the right medial temporal lobe than did the 'no depressive symptoms' group (p = 0.023). These results suggest that memory, executive function, and processing speed examinations are useful to identify cognitive decline in older adults who have depressive symptoms and depression. Serum BDNF concentration and atrophy of the right medial temporal lobe may in part mediate the relationships between depressive symptoms and cognitive decline.

  14. Transmission electron microscopy of thin sections of Drosophila: high-pressure freezing and freeze-substitution.

    PubMed

    McDonald, Kent L; Sharp, David J; Rickoll, Wayne

    2012-04-01

    The state of the art in fine-structure preservation for thin sectioning can be achieved by using fast-freezing technology followed by freeze substitution and embedding in resin. Samples prepared by high-pressure freezing are estimated to be "fixed" in 20-50 msec. Fast freezing also freezes every cell component regardless of its chemistry. Once frozen, tissues can be processed in a variety of ways before viewing in the electron microscope; here we describe only freeze substitution. In freeze substitution, cells are dehydrated at very low temperatures and cell water is replaced with organic solvent at -80°C to -90°C. At this temperature, large molecules such as proteins are immobilized, yet smaller molecules such as water (ice) can be dissolved and replaced with organic solvents, e.g., acetone. The ideal way to do freeze substitution is with a dedicated freeze-substitution device such as the Leica AFS2 system. These devices allow programming of the times and temperatures needed. Alternatively, if this equipment is not available, freeze substitution can still be performed using items commonly found around the laboratory, as is described here. This protocol is useful for preparing thin sections of Drosophila when the best possible preservation of ultrastructure and antigenicity is required.

  15. 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

  16. 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.

  17. Major depression.

    PubMed

    Bentley, Susan M; Pagalilauan, Genevieve L; Simpson, Scott A

    2014-09-01

    Major depression is a common, disabling condition seen frequently in primary care practices. Non-psychiatrist ambulatory providers are increasingly responsible for diagnosing, and primarily managing patients suffering from major depressive disorder (MDD). The goal of this review is to help primary care providers to understand the natural history of MDD, identify practical tools for screening, and a thoughtful approach to management. Clinically challenging topics like co-morbid conditions, treatment resistant depression and pharmacotherapy selection with consideration to side effects and medication interactions, are also covered.

  18. 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.

  19. Depression, masochism, and biology.

    PubMed

    Asch, S S

    1985-01-01

    In examining the conditions of depression and masochism, my intention has been to expand our area of study beyond psychodynamics alone. My first aim was to present what I believe are the intimately intertwined dynamics of each condition, a metaphorical double helix of depression and masochism in a matrix of narcissism. It may make clearer how either depression or masochism may present clinically in combination, at times in tandem, or manifestly as either state alone. My second, but major, aim is ecumenical: to interweave contributions from outside psychoanalysis. The neurophysiological bases and genetic determinants for most depressions are by now well-recognized. Masochism, much like depression, with which it is closely allied, may not necessarily arise out of conflict alone. I have presented brief excerpts of material, much of it still speculative, from areas of genetics, biochemistry, and ethology, to support the concept of a biological anlage for masochism. This would help explain the enormous difficulties therapists find in the path of its successful treatment. I believe Lorenz's theories on animal "bonding" suggest precursors to our concepts of masochism. I further believe our field of study has reached the point at which these and probably additional scientific disciplines can be helpful or even necessary for the further understanding of character, and for the solution of the persistent riddle of masochism, whose full understanding has continued to elude us. PMID:2991102

  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. Major depression

    MedlinePlus

    ... If depression is very severe, you may have hallucinations and delusions (false beliefs). This condition is called ... relieve your symptoms. If you have delusions or hallucinations, your provider may prescribe additional medicines. Tell your ...

  2. Neuroimaging of Freezing of Gait

    PubMed Central

    Fasano, Alfonso; Herman, Talia; Tessitore, Alessandro; Strafella, Antonio P.; Bohnen, Nicolaas I.

    2015-01-01

    Abstract Functional brain imaging techniques appear ideally suited to explore the pathophysiology of freezing of gait (FOG). In the last two decades, techniques based on magnetic resonance or nuclear medicine imaging have found a number of structural changes and functional disconnections between subcortical and cortical regions of the locomotor network in patients with FOG. FOG seems to be related in part to disruptions in the “executive-attention” network along with regional tissue loss including the premotor area, inferior frontal gyrus, precentral gyrus, the parietal and occipital areas involved in visuospatial functions of the right hemisphere. Several subcortical structures have been also involved in the etiology of FOG, principally the caudate nucleus and the locomotor centers in the brainstem. Maladaptive neural compensation may present transiently in the presence of acute conflicting motor, cognitive or emotional stimulus processing, thus causing acute network overload and resulting in episodic impairment of stepping. In this review we will summarize the state of the art of neuroimaging research for FOG. We will also discuss the limitations of current approaches and delineate the next steps of neuroimaging research to unravel the pathophysiology of this mysterious motor phenomenon. PMID:25757831

  3. 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.

  4. 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

  5. Trehalose levels and survival ratio of freeze-tolerant versus freeze-sensitive yeasts.

    PubMed

    Hino, A; Mihara, K; Nakashima, K; Takano, H

    1990-05-01

    Five freeze-tolerant yeast strains suitable for frozen dough were compared with ordinary commercial bakers' yeast. Kluyveromyces thermotolerans FRI 501 cells showed high survival ability after freezing when their resting cells were fermented for 0 to 180 min in modified liquid medium, and they grew to log and stationary phases. Among the freeze-tolerant strains of Saccharomyces cerevisiae, FRI 413 and FRI 869 showed higher surviving and trehalose-accumulating abilities than other S. cerevisiae strains, but were affected by a prolonged prefermentation period and by growth phases. The freeze tolerance of the yeasts was, to some extent, associated with the basal amount of intracellular trehalose after rapid degradation at the onset of the prefermentation period. In the freeze-sensitive yeasts, the degree of hydrolysis of trehalose may thus be affected by the kind of saccharide, unlike in freeze-tolerant yeasts. PMID:2339891

  6. Induction of Freeze-sensitive Mutants from a Freeze-tolerant Yeast, Torulaspora delbrueckii.

    PubMed

    Murakami, Y; Hahn, Y S; Yokoigawa, K; Endo, K; Kawai, H

    1994-01-01

    Freeze-sensitive strains of yeast were induced from a freeze-tolerant yeast Torulaspora delbrueckii by incubation with ethyl-methane sulfonate as a mutagen. A maximum ratio of mutation was attained by the incubation at 30°C for 75min. One-hundred and fifty strains of freeze-sensitive yeast were selected by plating-culture for the first screening. The freeze-tolerance ratio of each strain was examined based on the fermentative activity before and after freezing in liquid medium and dough. Strain 60B3 showed the highest freeze-sensitivity in a pre-fermented frozen dough (pre-fermented at 30°C for 2h, and frozen at -20°C for 7 days) among eight strains finally selected. PMID:27315725

  7. Flash-and-Freeze: Coordinating Optogenetic Stimulation with Rapid Freezing to Visualize Membrane Dynamics at Synapses with Millisecond Resolution

    PubMed Central

    Watanabe, Shigeki

    2016-01-01

    Electron microscopy depicts subcellular structures at synapses exquisitely but only captures static images. To visualize membrane dynamics, we have developed a novel technique, called flash-and-freeze, which induces neuronal activity with a flash of light and captures the membrane dynamics by rapid freezing. For characterizing membrane movements during synaptic transmission, a light-sensitive cation channel, channelrhodopsin, is heterologously expressed in mouse hippocampal neurons or in Caenorhabditis elegans motor neurons. A brief pulse of blue light activates channelrhodopsin and induces an action potential, leading to synaptic transmission. Following the light stimulation, neurons are frozen at different time intervals ranging from 10 ms to 20 s. Electron micrographs are then acquired from each time point to visualize the morphological changes. Using this approach, we have characterized a novel form of endocytosis, ultrafast endocytosis, which rapidly removes excess membrane added to the surface during neurotransmission. The flash-and-freeze approach can be adapted to study other cellular phenomena that can be induced by light-sensitive genetic or pharmacological tools.

  8. Flash-and-Freeze: Coordinating Optogenetic Stimulation with Rapid Freezing to Visualize Membrane Dynamics at Synapses with Millisecond Resolution.

    PubMed

    Watanabe, Shigeki

    2016-01-01

    Electron microscopy depicts subcellular structures at synapses exquisitely but only captures static images. To visualize membrane dynamics, we have developed a novel technique, called flash-and-freeze, which induces neuronal activity with a flash of light and captures the membrane dynamics by rapid freezing. For characterizing membrane movements during synaptic transmission, a light-sensitive cation channel, channelrhodopsin, is heterologously expressed in mouse hippocampal neurons or in Caenorhabditis elegans motor neurons. A brief pulse of blue light activates channelrhodopsin and induces an action potential, leading to synaptic transmission. Following the light stimulation, neurons are frozen at different time intervals ranging from 10 ms to 20 s. Electron micrographs are then acquired from each time point to visualize the morphological changes. Using this approach, we have characterized a novel form of endocytosis, ultrafast endocytosis, which rapidly removes excess membrane added to the surface during neurotransmission. The flash-and-freeze approach can be adapted to study other cellular phenomena that can be induced by light-sensitive genetic or pharmacological tools. PMID:27594835

  9. Flash-and-Freeze: Coordinating Optogenetic Stimulation with Rapid Freezing to Visualize Membrane Dynamics at Synapses with Millisecond Resolution

    PubMed Central

    Watanabe, Shigeki

    2016-01-01

    Electron microscopy depicts subcellular structures at synapses exquisitely but only captures static images. To visualize membrane dynamics, we have developed a novel technique, called flash-and-freeze, which induces neuronal activity with a flash of light and captures the membrane dynamics by rapid freezing. For characterizing membrane movements during synaptic transmission, a light-sensitive cation channel, channelrhodopsin, is heterologously expressed in mouse hippocampal neurons or in Caenorhabditis elegans motor neurons. A brief pulse of blue light activates channelrhodopsin and induces an action potential, leading to synaptic transmission. Following the light stimulation, neurons are frozen at different time intervals ranging from 10 ms to 20 s. Electron micrographs are then acquired from each time point to visualize the morphological changes. Using this approach, we have characterized a novel form of endocytosis, ultrafast endocytosis, which rapidly removes excess membrane added to the surface during neurotransmission. The flash-and-freeze approach can be adapted to study other cellular phenomena that can be induced by light-sensitive genetic or pharmacological tools. PMID:27594835

  10. The Identification of Postpartum Depression

    PubMed Central

    Sit, Dorothy K.; Wisner, Katherine L.

    2009-01-01

    Postpartum depression (PPD) is the most common medical complication of childbearing. Universal screening maximizes the likelihood of prompt identification of PPD. Obstetrician-gynecologists routinely evaluate postpartum women for a general health examination and review of family planning options at approximately 6 weeks after birth; therefore, they are well-positioned to identify PPD. In this paper, we review the diagnostic criteria for postpartum depressive disorders and clinical risk factors predictive of PPD. We examine depression screening tools, appropriate cut-points associated with positive screens, the optimal timing for screening and the acceptability of depression screening in obstetrical settings. Lastly, we explore how to manage patients who screen positive for depression and treatment options for women with PPD. PMID:19661761

  11. [MAJOR DEPRESSION AND PERSONALIZED MEDICINE].

    PubMed

    Pitchot, W

    2015-01-01

    Depression is a major public health problem. According to the World Health Organization (OMS), depression is currently the second cause of disability in developing countries. Depression is also one of the most frequent mental illnesses. When treating depression, the main objective is to achieve complete remission and to prevent recurrence. Unfor-tunately, in clinical practice, this aim is particularly difficult to reach. Indeed, in clinical trials and in naturalistic studies, remission levels are rather low. The challenge is to individualize the treatment of depression taking account clinical specificities, but also advances in the field of biological and genetic research. Today, intense psychiatric research tries to discover biomarkers to predict treatment response. Because individuals are highly different from a biological, psychological and sociological point of view, more personalized therapeutic approaches are recommended. PMID:26285462

  12. Freezing mammalian cells for production of biopharmaceuticals.

    PubMed

    Seth, Gargi

    2012-03-01

    Cryopreservation techniques utilize very low temperatures to preserve the structure and function of living cells. Various strategies have been developed for freezing mammalian cells of biological and medical significance. This paper highlights the importance and application of cryopreservation for recombinant mammalian cells used in the biopharmaceutical industry to produce high-value protein therapeutics. It is a primer that aims to give insight into the basic principles of cell freezing for the benefit of biopharmaceutical researchers with limited or no prior experience in cryobiology. For the more familiar researchers, key cell banking parameters such as the cell density and hold conditions have been reviewed to possibly help optimize their specific cell freezing protocols. It is important to understand the mechanisms underlying the freezing of complex and sensitive cellular entities as we implement best practices around the techniques and strategies used for cryopreservation. PMID:22226818

  13. 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.

  14. Comparison of three-dimensional printing and vacuum freeze-dried techniques for fabricating composite scaffolds.

    PubMed

    Sun, Kai; Li, Ruixin; Jiang, Wenxue; Sun, Yufu; Li, Hui

    2016-09-01

    In this study, the performances of different preparation methods of the scaffolds were analyzed for chondrocyte tissue engineering. Silk fibroin/collagen (SF/C) was fabricated using a vacuum freeze-dried technique and by 3D printing. The porosity, water absorption expansion rates, mechanical properties, and pore sizes of the resulting materials were evaluated. The proliferation and metabolism of the cells was detected at different time points using an MTT assay. Cell morphologies and distributions were observed by histological analysis and scanning electron microscopy (SEM). The porosity, water absorption expansion rate, and Young's modulus of the material obtained via 3D printing were significantly higher than those obtained by the freeze-dried method, while the pore size did not differ significantly between the two methods. MTT assay results showed that the metabolism of cells seeded on the 3D printed scaffolds was more viable than the metabolism on the freeze-dried material. H&E staining of the scaffolds revealed that the number of cells in the 3D printed scaffold was higher in comparison to a similar measurement on the freeze-dried material. Consequently, stem cells grew well inside the 3D printed scaffolds, as measured by SEM, while the internal structure of the freeze-dried scaffold was disordered. Compared with the freeze-dried technique, the 3D printed scaffold exhibited better overall performance and was more suitable for cartilage tissue engineering. PMID:27404126

  15. 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.

  16. Comparison of three-dimensional printing and vacuum freeze-dried techniques for fabricating composite scaffolds.

    PubMed

    Sun, Kai; Li, Ruixin; Jiang, Wenxue; Sun, Yufu; Li, Hui

    2016-09-01

    In this study, the performances of different preparation methods of the scaffolds were analyzed for chondrocyte tissue engineering. Silk fibroin/collagen (SF/C) was fabricated using a vacuum freeze-dried technique and by 3D printing. The porosity, water absorption expansion rates, mechanical properties, and pore sizes of the resulting materials were evaluated. The proliferation and metabolism of the cells was detected at different time points using an MTT assay. Cell morphologies and distributions were observed by histological analysis and scanning electron microscopy (SEM). The porosity, water absorption expansion rate, and Young's modulus of the material obtained via 3D printing were significantly higher than those obtained by the freeze-dried method, while the pore size did not differ significantly between the two methods. MTT assay results showed that the metabolism of cells seeded on the 3D printed scaffolds was more viable than the metabolism on the freeze-dried material. H&E staining of the scaffolds revealed that the number of cells in the 3D printed scaffold was higher in comparison to a similar measurement on the freeze-dried material. Consequently, stem cells grew well inside the 3D printed scaffolds, as measured by SEM, while the internal structure of the freeze-dried scaffold was disordered. Compared with the freeze-dried technique, the 3D printed scaffold exhibited better overall performance and was more suitable for cartilage tissue engineering.

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

    PubMed

    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.

  18. 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.

  19. Freezing of Xylem Sap Without Cavitation

    PubMed Central

    Hammel, H. T.

    1967-01-01

    Freezing of stem sections and entire twigs of hemlock (Tsuga canadensis) has been demonstrated to occur without increasing the resistance to the movement of water through the frozen part after rewarming. This was interpreted to mean that freezing did not produce cavitation in the xylem sap even though A) the sap was unquestionably frozen; B) it contained dissolved gases; and C) it was under tension before freezing and after. Freezing stem sections of some other evergreen gymnosperms during the summer again produced no evidence for cavitation of the xylem sap. On the other hand, freezing stem sections of some angiosperms invariably increased the resistance to sap flow leading to wilting and death in a few hours when the sap tension was at normal daytime values at the time of freezing. These results were interpreted to mean that the bordered pits on the tracheids of gymnosperms function to isolate the freezing sap in each tracheid so that the expansion of water upon freezing not only eliminates any existing tension but also develops positive pressure in the sap. Dissolved gases frozen out of solution may then be redissolved under this positive pressure as melting occurs. As the bubbles are reduced in size by this ice pressure developed in an isolated tracheid, further pressure is applied by the surface tension of the water against air. If the bubbles are redissolved or are reduced to sufficient small size by the time the tension returns to the sap as the last ice crystals melt, then the internal pressure from surface tension in any existing small bubbles may exceed the hydrostatic tension of the melted sap and the bubbles cannot expand and will continue to dissolve. PMID:16656485

  20. Quality changes and freezing time prediction during freezing and thawing of ginger.

    PubMed

    Singha, Poonam; Muthukumarappan, Kasiviswanathan

    2016-07-01

    Effects of different freezing rates and four different thawing methods on chemical composition, microstructure, and color of ginger were investigated. Computer simulation for predicting the freezing time of cylindrical ginger for two different freezing methods (slow and fast) was done using ANSYS (®) Multiphysics. Different freezing rates (slow and fast) and thawing methods significantly (P < 0.05) affected the color and composition of essential oil in ginger. Fresh ginger was found to contain 3.60% gingerol and 18.30% zingerone. A maximum yield of 7.43% gingerol was obtained when slow frozen gingers when thawed by infrared method. Maximum zingerone content of 38.30% was achieved by thawing slow frozen gingers using infrared-microwave method. Microscopic examination revealed that structural damage was more pronounced in slow frozen gingers than fast frozen gingers. Simulated freezing curves were in good agreement with experimental measurements (r = 0.97 for slow freezing and r = 0.92 for fast freezing). Slow freezing damaged ginger's cellular structure. Data obtained will be helpful in selecting appropriate thawing method to increase desirable essential oil components in ginger. Computer simulation for predicting freezing time may help in developing proper storage system of ginger. PMID:27386102

  1. Effects of freezing on bone histological morphology.

    PubMed

    Andrade, Miguel Gustavo Setúbal; Sá, Camila Neves; Marchionni, Antônio Márcio Teixeira; dos Santos Calmon de Bittencourt, Thereza Cristina Bório; Sadigursky, Moysés

    2008-12-01

    Allograft bone has been widely used for reconstruction of different portions of the skeleton. The fragment of bone harvested must be kept under low temperatures. The cryopreservation also contributes to decrease the antigenic potential of the tissue. Although this technique is considered safe, there is little information about the morphological modifications that the medullary and cortical portions of bone suffer after freezing. Hence, the aim of this study was to investigate the morphology of bone tissue after freezing under different temperatures and periods. Twelve rabbits were used to analyze the effects of two temperatures, -20 degrees C and -70 degrees C, during four periods of time: 30, 60, 90, 120 days. Tissues were analyzed by HE, picro-sirius stains and also by Feulgen's reaction, through qualitative and morphometric ways, considering the area occupied by cells and nuclei, medullary and cortical portions, as well as by collagen expression at cortical. The differences among the treatments were analyzed by Tukey s test, at 5% significance level. Bone freezing increased cellular and nuclear areas at cancellous bone and diminished nuclear area at the cortical bone. Cortical bone collagen suffered denaturation proportionally to temperature decrease and to freezing duration. These alterations compromised the morphology of tissues after 90 or 120 days of freezing at the temperature of -70 degrees C. Cells necrosed during freezing, contributing to reduce bone antigenicity.

  2. 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.

  3. 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.

  4. 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

  5. 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...

  6. 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...

  7. Freezing and melting equations for the n-6 Lennard-Jones systems

    NASA Astrophysics Data System (ADS)

    Khrapak, Sergey A.; Ning, Ning

    2016-05-01

    We generalize previous approach of Khrapak and Morfill [J. Chem. Phys. 134, 094108 (2011)] to construct simple and sufficiently accurate freezing and melting equations for the conventional Lennard-Jones (LJ) system to n-6 LJ systems, using the accurate results for the triple points of these systems published by Sousa et al. [J. Chem. Phys. 136, 174502 (2012)].

  8. Understanding Depression (For Parents)

    MedlinePlus

    ... daylight are shorter; for example, during winter months. Bipolar disorder (also called manic depression or bipolar depression) is ... to a Therapist Anxiety Disorders Cutting Word! Depression Bipolar Disorder Why Am I So Sad? Sadness and Depression ...

  9. 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

  10. 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.

  11. Maternal Depression and Infant Temperament Characteristics

    PubMed Central

    McGrath, Jacqueline M.; Records, Kathie; Rice, Michael

    2008-01-01

    One hundred-thirty-nine women participated in this longitudinal study from the third trimester of pregnancy through 8-months postpartum. Women completed depression scales at several time points and rated their infant’s characteristics and childcare stress at 2- and 6-months postpartum. Mothers’ reports of infant temperament were significantly different for depressed and non-depressed mothers, with depressed mothers reporting more difficult infants at both measurement points. These differences remained after controlling for histories of maternal abuse or prenatal anxiety, which occurred more often in the depressed mothers. There were no significant differences in childcare stress or perceived support between the groups. Infant temperament and childcare stress did not change over time. Recommendations for practice include consistent ongoing evaluations of the “goodness of fit” within the dyad and exploring interventions for depressed mothers that provide guidance about interactions with their infants and the appropriateness of the infant behaviors. PMID:17714790

  12. 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

  13. 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.

  14. Heat transfer coefficient of cryotop during freezing.

    PubMed

    Li, W J; Zhou, X L; Wang, H S; Liu, B L; Dai, J J

    2013-01-01

    Cryotop is an efficient vitrification method for cryopreservation of oocytes. It has been widely used owing to its simple operation and high freezing rate. Recently, the heat transfer performance of cryotop was studied by numerical simulation in several studies. However, the range of heat transfer coefficient in the simulation is uncertain. In this study, the heat transfer coefficient for cryotop during freezing process was analyzed. The cooling rates of 40 percent ethylene glycol (EG) droplet in cryotop during freezing were measured by ultra-fast measurement system and calculated by numerical simulation at different value of heat transfer coefficient. Compared with the results obtained by two methods, the range of the heat transfer coefficient necessary for the numerical simulation of cryotop was determined, which is between 9000 W/(m(2)·K) and 10000 W/(m (2)·K).

  15. Freeze substitution in 3 hours or less.

    PubMed

    McDonald, K L; Webb, R I

    2011-09-01

    Freeze substitution is a process for low temperature dehydration and fixation of rapidly frozen cells that usually takes days to complete. New methods for freeze substitution have been developed that require only basic laboratory tools: a platform shaker, liquid nitrogen, a metal block with holes for cryotubes and an insulated container such as an ice bucket. With this equipment, excellent freeze substitution results can be obtained in as little as 90 min for cells of small volume such as bacteria and tissue culture cells. For cells of greater volume or that have significant diffusion barriers such as cuticles or thick cell walls, one can extend the time to 3 h or more with dry ice. The 3-h method works well for all manner of specimens, including plants and Caenorhabditis elegans as well as smaller samples. Here, we present the basics of the techniques and some results from Nicotiana leaves, C. elegans adult worms, Escherichia coli and baby hamster kidney tissue culture cells.

  16. Freeze verification: time for a fresh approach

    SciTech Connect

    Paine, C.

    1983-01-01

    The administration's claim that some elements of a comprehensive nuclear freeze are unverifiable does not specify the nature of those elements and whether they represent a real threat to national security if we trusted the USSR to comply. The author contends that clandestine development of new weapons will have little strategic effect since both sides already have total destructive power. The risks of noncompliance are largely political and less than the risks of continued arms buildup. Since the USSR would also want the US to be bound by freeze terms, deterrence would come from mutual benefit. Hardliners argue that cheating is easier in a closed society; that our democracy would tend to relax and the USSR would move ahead with its plans for world domination. The author argues that, over time, a freeze would diminish Soviet confidence in its nuclear war fighting capabilities and that adequate verification is possible with monitoring and warning arrangements. (DCK)

  17. 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.

  18. Depression Sudden Gains and Transient Depression Spikes During Treatment for PTSD

    PubMed Central

    Keller, Stephanie M.; Feeny, Norah C.; Zoellner, Lori A.

    2014-01-01

    Objective We know little about how change unfolds in depression symptoms during PTSD treatment or how patient characteristics predict depression symptom change. This study examined critical transition points in depression symptoms during PTSD treatment, namely depression sudden gains, which are rapid symptom improvements and transient depression spikes, which are transient depression worsenings. Social support, one of the strongest predictors of PTSD development, was examined as a predictor of depression symptom discontinuities. Method At pre-treatment, 200 participants (76.6% female; 64.9% Caucasian; age (M = 37.1 (SD = 11.3) years) completed measures of PTSD severity (PTSD Symptom Scale-Self Report), depression severity (Beck Depression Inventory), general social support (Inventory of Socially Supportive Behaviors; Social Support Questionnaire), and trauma-related social support (Social Reactions Questionnaire). During 10 weeks of prolonged exposure (PE) or sertraline, depression was assessed weekly. Results Overall, 18.0% of participants experienced a depression sudden gain and 22.5% experienced a transient depression spike. The presence of a depression sudden gain predicted better treatment outcome, β = −4.82, SE = 1.17, p = .001, 95% CI [−6.79, −2.90]. Higher perceptions of negative trauma-related reactions, albeit modestly, were associated with experiencing a transient depression spike (r = .18, p = .01). There were no differences in rates of depression sudden gains or transient depression spikes between treatments. Conclusions Encouragingly, rapid improvements in depression symptoms are beneficial for PTSD treatment outcome but transient spikes in depressive symptoms do not strongly influence outcome. Understanding symptom discontinuities may help us to personalize current PTSD treatment options. PMID:24364793

  19. 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

  20. 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.

  1. 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.

  2. A prospective study of freezing of gait with early Parkinson disease in Chinese patients

    PubMed Central

    Zhang, Hongbo; Yin, Xifan; Ouyang, Zhiyuan; Chen, Jing; Zhou, Shenghua; Zhang, Changguo; Pan, Xin; Wang, Shiliang; Yang, Junxiang; Feng, Yaoyao; Yu, Ping; Zhang, Qiangchun

    2016-01-01

    Abstract This study investigated the risk factors for freezing of gait (FOG) in the early stage of Parkinson disease in China, using a sample of 248 patients who were followed for 3 years. Part III of the Unified Parkinson Disease Rating Scale and the modified Hoehn-Yahr grading scale were used to evaluate the severity of motor symptoms. Nonmotor symptoms were assessed using the Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale (HAMD), and Non-Motor Symptoms Scale (NMSS). The end-point was the presence of FOG at the end of follow-up; patients with FOG were classified as freezers. The risk factors for FOG were analyzed at the end of the first, second, and third years after baseline. There were 40 freezers (16.13%) 1 year later, 98 (39.52%) 2 years later, and 128 (51.61%) 3 years later. FOG 3 years later was associated with the following variables: depression (P = 0.003), older age, living in the countryside, lower education, akinetic-rigid style, lower limbs as site of onset, early use of levodopa, higher daily dose of levodopa, and not using amantadine or selegiline and dopamine receptor agonists (P < 0.001). Early use of amantadine, selegiline, and dopamine receptor agonists was negatively related to FOG (P < 0.001). Binary logistic regression found that FOG was associated with lower education (odds ratio [OR] = 0.012, P < 0.001), akinetic-rigid style (OR = 4.881, P = 0.024), not using dopamine receptor agonists (OR = 4.324, P = 0.035), cognitive disturbances (OR = 0.331, P = 0.007), and sleep disorders (OR = 2.418, P = 0.036). However, the cardiovascular domain of the NMSS (OR = 2.729, P = 0.001) was the only risk factor for FOG 1 year later. Two years later, FOG was associated with mixed style (OR = 0.189, P = 0.005), lower limbs as site of onset (OR = 4.772, P = 0.008), not using dopamine receptor agonists (OR = 0.031, P < 0.001), and the anxiety/somatic domain of the HAMD (OR = 0.596, P = 0.033). Scores at baseline, patients with

  3. A prospective study of freezing of gait with early Parkinson disease in Chinese patients.

    PubMed

    Zhang, Hongbo; Yin, Xifan; Ouyang, Zhiyuan; Chen, Jing; Zhou, Shenghua; Zhang, Changguo; Pan, Xin; Wang, Shiliang; Yang, Junxiang; Feng, Yaoyao; Yu, Ping; Zhang, Qiangchun

    2016-06-01

    This study investigated the risk factors for freezing of gait (FOG) in the early stage of Parkinson disease in China, using a sample of 248 patients who were followed for 3 years. Part III of the Unified Parkinson Disease Rating Scale and the modified Hoehn-Yahr grading scale were used to evaluate the severity of motor symptoms. Nonmotor symptoms were assessed using the Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale (HAMD), and Non-Motor Symptoms Scale (NMSS). The end-point was the presence of FOG at the end of follow-up; patients with FOG were classified as freezers. The risk factors for FOG were analyzed at the end of the first, second, and third years after baseline. There were 40 freezers (16.13%) 1 year later, 98 (39.52%) 2 years later, and 128 (51.61%) 3 years later. FOG 3 years later was associated with the following variables: depression (P = 0.003), older age, living in the countryside, lower education, akinetic-rigid style, lower limbs as site of onset, early use of levodopa, higher daily dose of levodopa, and not using amantadine or selegiline and dopamine receptor agonists (P < 0.001). Early use of amantadine, selegiline, and dopamine receptor agonists was negatively related to FOG (P < 0.001). Binary logistic regression found that FOG was associated with lower education (odds ratio [OR] = 0.012, P < 0.001), akinetic-rigid style (OR = 4.881, P = 0.024), not using dopamine receptor agonists (OR = 4.324, P = 0.035), cognitive disturbances (OR = 0.331, P = 0.007), and sleep disorders (OR = 2.418, P = 0.036). However, the cardiovascular domain of the NMSS (OR = 2.729, P = 0.001) was the only risk factor for FOG 1 year later. Two years later, FOG was associated with mixed style (OR = 0.189, P = 0.005), lower limbs as site of onset (OR = 4.772, P = 0.008), not using dopamine receptor agonists (OR = 0.031, P < 0.001), and the anxiety/somatic domain of the HAMD (OR = 0.596, P = 0.033). Scores at baseline, patients with Parkinson

  4. 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

  5. Cryoprotectant Production in Freeze-Tolerant Wood Frogs Is Augmented by Multiple Freeze-Thaw Cycles.

    PubMed

    Larson, Don J; Barnes, Brian M

    2016-01-01

    Ice nucleation across the skin of wood frogs (Lithobates sylvaticus) rapidly induces endogenous production of glucose, a cryoprotectant necessary for freeze tolerance. In laboratory studies of freeze tolerance, wood frogs are cooled slowly, often at -0.05°C h(-1), to facilitate high cryoprotectant production and survival. Under natural conditions in Alaska, however, wood frogs accumulate maximal tissue glucose concentrations while cooling at much faster rates, -0.35° to -1.6°C h(-1), and in addition undergo multiple successive freeze-thaw cycles before remaining frozen for the winter. We examined whether simulating these ecologically relevant cooling rates and repeated freeze-thaw events in captive wood frogs results in the high glucose concentrations found in naturally frozen wood frogs. We found that over successive freezing and thawing events, glucose concentrations increased stepwise in all measured tissues. Short thawing periods did not result in a statistically significant decline of glucose concentrations. Wood frogs that experienced three freeze-thaw events had fresh weight glucose concentrations that approached values found in tissues of wood frogs frozen in natural conditions. Laboratory wood frogs survive frozen for 2 mo, while wood frogs frozen under natural conditions survive frozen for up to 7 mo at temperatures below -18°C. We hypothesize that repeated freeze-thaw cycles with rapid cooling and warming rates allow for greater survival in Alaskan wood frogs through enhanced cryoprotectant production. PMID:27327184

  6. Cryoprotectant Production in Freeze-Tolerant Wood Frogs Is Augmented by Multiple Freeze-Thaw Cycles.

    PubMed

    Larson, Don J; Barnes, Brian M

    2016-01-01

    Ice nucleation across the skin of wood frogs (Lithobates sylvaticus) rapidly induces endogenous production of glucose, a cryoprotectant necessary for freeze tolerance. In laboratory studies of freeze tolerance, wood frogs are cooled slowly, often at -0.05°C h(-1), to facilitate high cryoprotectant production and survival. Under natural conditions in Alaska, however, wood frogs accumulate maximal tissue glucose concentrations while cooling at much faster rates, -0.35° to -1.6°C h(-1), and in addition undergo multiple successive freeze-thaw cycles before remaining frozen for the winter. We examined whether simulating these ecologically relevant cooling rates and repeated freeze-thaw events in captive wood frogs results in the high glucose concentrations found in naturally frozen wood frogs. We found that over successive freezing and thawing events, glucose concentrations increased stepwise in all measured tissues. Short thawing periods did not result in a statistically significant decline of glucose concentrations. Wood frogs that experienced three freeze-thaw events had fresh weight glucose concentrations that approached values found in tissues of wood frogs frozen in natural conditions. Laboratory wood frogs survive frozen for 2 mo, while wood frogs frozen under natural conditions survive frozen for up to 7 mo at temperatures below -18°C. We hypothesize that repeated freeze-thaw cycles with rapid cooling and warming rates allow for greater survival in Alaskan wood frogs through enhanced cryoprotectant production.

  7. KINETICS OF WATER LOSS FROM CELLS AT SUBZERO TEMPERATURES AND THE LIKELIHOOD OF INTRACELLULAR FREEZING.

    PubMed

    MAZUR, P

    1963-11-01

    The survival of various cells subjected to low temperature exposure is higher when they are cooled slowly. This increase is consistent with the view that slow cooling decreases the probability of intracellular freezing by permitting water to leave the cell rapidly enough to keep the protoplasm at its freezing point. The present study derives a quantitative relation between the amount of water in a cell and temperature. The relation is a differential equation involving cooling rate, surface-volume ratio, membrane permeability to water, and the temperature coefficient of the permeability constant. Numerical solutions to this equation give calculated water contents which permit predictions as to the likelihood of intracellular ice formation. Both the calculated water contents and the predictions on internal freezing are consistent with the experimental observations of several investigators. PMID:14085017

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. Process feasibility investigation of freezing free litho-litho-etch process for below 32nm hp

    NASA Astrophysics Data System (ADS)

    Nakamura, Tsuyoshi; Takeshita, Masaru; Yokoya, Jiro; Yoshii, Yasuhiro; Saito, Hirokuni; Takasu, Ryoichi; Ohmori, Katsumi

    2010-04-01

    Double patterning with 193nm immersion lithography becomes to most promising candidate for 32nm half pitch node and possibly below 32nm half pitch. Several double patterning methods have been suggested such as LELE (Litho-Etch -Litho-Etch), LLE (Litho-Litho-Etch) and Spacer defined process, however, LLE process is pointed out as low cost double patterning technique because of its simplicity. But LLE process needs new method to maintain 1st lithography pattern and additional freezing processes have been suggested In SPIE Advanced Lithography 2009, freezing free "Posi/Posi" process was introduced as candidate for LLE process. This is LLE process that uses two different positive tone photoresists without freezing process. The resist for 2nd lithography contains a specific solvent to prevent the mixing of two resists and there is an activation energy gap between 1st and 2nd resists to maintain 1st lithography pattern. The double patterning can be successfully processed by these specific resists without freezing process. In this study, the performance of this freezing free "Posi/Posi" process is investigated for pitch splitting pattern using 1.35 NA exposure tool. The imaging results including CD control capability, and etching results are collected for 32nm half pitch and below. Additionally the two-dimensional pattern imaging is also obtained for 76nm minimum pitch.

  15. 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.

  16. 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.

  17. Susceptibility of blackberry flowers to freezing temperatures

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Injury of tight buds, open flowers and green fruit often occur in fruit crops during spring frost events. In this study, freezing tolerance of ‘Triple Crown’ blackberry flowers at different reproductive stages of development (tight bud to green drupe) was determined using two methods. One method i...

  18. 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…

  19. Theoretical prediction of 'optimal' freezing programmes.

    PubMed

    Woelders, H; Chaveiro, A

    2004-12-01

    We have developed a quantitative description of the osmotic behaviour of cells during freezing without a presupposed value of the cooling rate. Instead, at all times the intracellular supercooling is maximised provided that it does not exceed a predetermined value 'p' (e.g., 2 degrees C). This should preclude intracellular ice formation, but also ensures that the osmotic gradient and the CPA concentration gradient are limited, as well as the gradient driven transmembrane fluxes of water and CPA. Using the condition of a constant level of supercooling of p degrees C, equations can be derived to generate non-linear cooling curves in which at all times the cooling rate is maximised (to minimise slow cooling damage), while preventing conditions that could lead to fast cooling damage. Simulations of the osmotic events during freezing, and prediction of the 'optimal' freezing curve can be performed provided that values are available for the membrane permeability coefficients for water (L(p)) and cryoprotectant (P(s)), and their respective activation energies, the initial intracellular osmotically active aqueous volume, and the membrane surface area. Simulations are shown, both with and without permeant solute, to demonstrate how the predicted 'optimal' freezing curve is affected by medium composition, and by membrane permeability and osmotic cell characteristics.

  20. Vaporized hydrogen peroxide sterilization of freeze dryers.

    PubMed

    Johnson, J W; Arnold, J F; Nail, S L; Renzi, E

    1992-01-01

    The feasibility of using vapor hydrogen peroxide (VHP) as an alternative to steam sterilization has been examined using a pilot plant freeze dryer equipped with a prototype vapor generator. Specific objectives of the study discussed in this presentation were to: 1. Identify critical process variables affecting the lethality of VHP to Bacillus stearothermophilus spores, particularly within dead legs in the system. 2. Measure the efficacy of system degassing after sterilization. 3. Determine the effect of repeated sterilization cycles on the integrity of elastomeric components of the freeze dryer. Penetration of adequate concentrations of hydrogen peroxide vapor into small diameter piping, such as tubing connected to pressure gauges, is the most challenging aspect of VHP sterilization of freeze dryers. Prior to equipment modifications, spore strips placed within such dead legs remained positive irrespective of the number of gas/degas pulses and system pressure. Equipment modifications necessary to effect complete kill of biological indicators placed in system dead legs is discussed. Results of this study support the conclusion that vaporized hydrogen peroxide shows promise as an alternative sterilization method for freeze dryers. PMID:1474433

  1. 47 CFR 64.636 - Prohibition of default provider freezes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... (a) A default provider freeze prevents a change in an iTRS user's default provider selection unless the iTRS user gives the provider from whom the freeze was requested his or her express consent....

  2. 47 CFR 64.636 - Prohibition of default provider freezes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... (a) A default provider freeze prevents a change in an iTRS user's default provider selection unless the iTRS user gives the provider from whom the freeze was requested his or her express consent....

  3. 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

  4. 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.

  5. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... bridge construction or safety, the FHWA will inform the State, and the original conditions of the freeze... safety purposes and road construction, a State may make minor adjustments of a temporary and...

  6. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... bridge construction or safety, the FHWA will inform the State, and the original conditions of the freeze... safety purposes and road construction, a State may make minor adjustments of a temporary and...

  7. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... bridge construction or safety, the FHWA will inform the State, and the original conditions of the freeze... safety purposes and road construction, a State may make minor adjustments of a temporary and...

  8. 23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... bridge construction or safety, the FHWA will inform the State, and the original conditions of the freeze... safety purposes and road construction, a State may make minor adjustments of a temporary and...

  9. 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.

  10. 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.

  11. 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

  12. Tandem High-pressure Freezing and Quick Freeze Substitution of Plant Tissues for Transmission Electron Microscopy

    PubMed Central

    Bobik, Krzysztof; Dunlap, John R.; Burch-Smith, Tessa M.

    2014-01-01

    Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, because of laborious and time-consuming protocols that also demand experience in preparation of artifact-free samples, TEM is not considered a user-friendly technique. Traditional sample preparation for TEM used chemical fixatives to preserve cellular structures. High-pressure freezing is the cryofixation of biological samples under high pressures to produce very fast cooling rates, thereby restricting ice formation, which is detrimental to the integrity of cellular ultrastructure. High-pressure freezing and freeze substitution are currently the methods of choice for producing the highest quality morphology in resin sections for TEM. These methods minimize the artifacts normally associated with conventional processing for TEM of thin sections. After cryofixation the frozen water in the sample is replaced with liquid organic solvent at low temperatures, a process called freeze substitution. Freeze substitution is typically carried out over several days in dedicated, costly equipment. A recent innovation allows the process to be completed in three hours, instead of the usual two days. This is typically followed by several more days of sample preparation that includes infiltration and embedding in epoxy resins before sectioning. Here we present a protocol combining high-pressure freezing and quick freeze substitution that enables plant sample fixation to be accomplished within hours. The protocol can readily be adapted for working with other tissues or organisms. Plant tissues are of special concern because of the presence of aerated spaces and water-filled vacuoles that impede ice-free freezing of water. In addition, the process of chemical fixation is especially long in plants due to cell walls impeding the penetration of the chemicals to deep within the tissues. Plant tissues are therefore particularly challenging, but

  13. Tandem high-pressure freezing and quick freeze substitution of plant tissues for transmission electron microscopy.

    PubMed

    Bobik, Krzysztof; Dunlap, John R; Burch-Smith, Tessa M

    2014-10-13

    Since the 1940s transmission electron microscopy (TEM) has been providing biologists with ultra-high resolution images of biological materials. Yet, because of laborious and time-consuming protocols that also demand experience in preparation of artifact-free samples, TEM is not considered a user-friendly technique. Traditional sample preparation for TEM used chemical fixatives to preserve cellular structures. High-pressure freezing is the cryofixation of biological samples under high pressures to produce very fast cooling rates, thereby restricting ice formation, which is detrimental to the integrity of cellular ultrastructure. High-pressure freezing and freeze substitution are currently the methods of choice for producing the highest quality morphology in resin sections for TEM. These methods minimize the artifacts normally associated with conventional processing for TEM of thin sections. After cryofixation the frozen water in the sample is replaced with liquid organic solvent at low temperatures, a process called freeze substitution. Freeze substitution is typically carried out over several days in dedicated, costly equipment. A recent innovation allows the process to be completed in three hours, instead of the usual two days. This is typically followed by several more days of sample preparation that includes infiltration and embedding in epoxy resins before sectioning. Here we present a protocol combining high-pressure freezing and quick freeze substitution that enables plant sample fixation to be accomplished within hours. The protocol can readily be adapted for working with other tissues or organisms. Plant tissues are of special concern because of the presence of aerated spaces and water-filled vacuoles that impede ice-free freezing of water. In addition, the process of chemical fixation is especially long in plants due to cell walls impeding the penetration of the chemicals to deep within the tissues. Plant tissues are therefore particularly challenging, but

  14. Microtubule structure studied by quick freezing: cryo-electron microscopy and freeze fracture.

    PubMed

    Mandelkow, E M; Rapp, R; Mandelkow, E

    1986-03-01

    Microtubules have been quickly frozen and examined by electron microscopy using several techniques: (1) freezing of a thin layer of solution by plunging into cryogen, followed by cryoelectron microscopy of the unstained vitrified samples; (2) freezing by the propane-jet method, followed by freeze fracturing and metal replication. The unstained frozen-hydrated microtubules show a structure in agreement with X-ray diffraction data; they differ from negatively stained particles mainly by the better preservation of cylindrical shape. Secondly, they reveal a supertwist of the profilaments that is not detected reliably by other methods. This allows a determination of the number of protofilaments and the polarity. The structural resolution of unstained microtubules is similar to that of stained ones (about 2-3 nm); it is limited by low contrast and lack of crystalline order. Propane-jet or cryo-block freezing followed by freeze fracturing reveals the structures of the inner and outer surfaces of the microtubule wall at a resolution of 4 nm or better. The outside is dominated by the longitudinal protofilaments whereas on the inside one observes tilted cross-striations. Although the freezing temperatures of the two methods are different (liquid nitrogen or helium) they yield similar results for the case of thin layers of protein solution. PMID:3517351

  15. Freezing and cryoprotective dehydration in an Antarctic nematode (Panagrolaimus davidi) visualised using a freeze substitution technique.

    PubMed

    Wharton, D A; Downes, M F; Goodall, G; Marshall, C J

    2005-02-01

    The pattern of ice formation during the freezing of Panagrolaimus davidi, an Antarctic nematode that can survive intracellular ice formation, was visualised using a freeze substitution technique and transmission electron microscopy. Nematodes plunged directly into liquid nitrogen had small ice crystals throughout their tissues, including nuclei and organelles, but did not survive. Those frozen at high subzero temperatures showed three patterns of ice formation: no ice, extracellular ice, and intracellular ice. Nematodes subjected to a slow-freezing regime (at -1 degrees C) had mainly extracellular ice (70.4%), with the bulk of the ice in the pseudocoel. Some (24.8%) had no ice within their bodies, due to cryoprotective dehydration. Nematodes subjected to a fast-freezing regime (at -4 degrees C) had intracellular (54%) and extracellular (42%) ice. Intracellular ice was confined to the cytoplasm of cells, with organelles in the spaces in between ice crystals. The survival of nematodes subjected to the fast-freezing regime (53%) was less than those subjected to the slow-freezing regime (92%).

  16. 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.

  17. Significant melting point depression of two-dimensional folded-chain crystals of isotactic poly(methyl methacrylate)s observed by high-resolution in situ atomic force microscopy.

    PubMed

    Takanashi, Yuma; Kumaki, Jiro

    2013-05-01

    The properties of polymer ultrathin films are a subject of intense study from both practical and academic viewpoints. Previously, we found that upon compression, an isotactic poly(methyl methacrylate) (it-PMMA) Langmuir monolayer crystallized to form a two-dimensional (2D) folded-chain crystal, and the molecular image of the crystal with chain folding and tie chains was clearly visualized by atomic force microscopy (AFM). In the present study, the melting behaviors of the it-PMMA 2D crystals were successfully observed in situ by high-temperature AFM at the molecular lever for the first time. The chain-chain distances (~1.2 nm) of the crystals were clearly resolved even at temperatures close to the melting temperatures (Tm) of the 2D crystals. We found that the Tm of the 2D crystals was at most 90 °C lower than the bulk crystals. The Tm depression strongly depended on the molecular weight, while the molecular weight dependence of the bulk Tm was negligible in the molecular weight regime studied. The Tm depression also depended on the substrates, a slightly larger depression being observed on a sapphire substrate compared to that on a mica. The large Tm depressions of the 2D crystals could not be explained by a simple Thomson-Gibbs argument, theoretical developments are necessary to understand the melting of the 2D crystals.

  18. 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...

  19. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... procedures necessary to lift a preferred carrier freeze; an explanation that these steps are in addition to... selection unless he or she lifts the freeze. (iii) An explanation of any charges associated with the... unable to make a change in carrier selection unless she or he lifts the preferred carrier freeze; and...

  20. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... procedures necessary to lift a preferred carrier freeze; an explanation that these steps are in addition to... selection unless he or she lifts the freeze. (iii) An explanation of any charges associated with the... unable to make a change in carrier selection unless she or he lifts the preferred carrier freeze; and...

  1. 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...

  2. 7 CFR 305.7 - Quick freeze treatment requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 5 2014-01-01 2014-01-01 false Quick freeze treatment requirements. 305.7 Section 305... INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS § 305.7 Quick freeze treatment requirements. Quick freeze treatment for fruits and vegetables imported into the United States or...

  3. 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.

  4. Learning and memory impairments in a neuroendocrine mouse model of anxiety/depression.

    PubMed

    Darcet, Flavie; Mendez-David, Indira; Tritschler, Laurent; Gardier, Alain M; Guilloux, Jean-Philippe; David, Denis J

    2014-01-01

    Cognitive disturbances are often reported as serious incapacitating symptoms by patients suffering from major depressive disorders (MDDs). Such deficits have been observed in various animal models based on environmental stress. Here, we performed a complete characterization of cognitive functions in a neuroendocrine mouse model of depression based on a chronic (4 weeks) corticosterone administration (CORT). Cognitive performances were assessed using behavioral tests measuring episodic (novel object recognition test, NORT), associative (one-trial contextual fear conditioning, CFC), and visuo-spatial (Morris water maze, MWM; Barnes maze, BM) learning/memory. Altered emotional phenotype after chronic corticosterone treatment was confirmed in mice using tests predictive of anxiety or depression-related behaviors. In the NORT, CORT-treated mice showed a decrease in time exploring the novel object during the test session and a lower discrimination index compared to control mice, characteristic of recognition memory impairment. Associative memory was also impaired, as observed with a decrease in freezing duration in CORT-treated mice in the CFC, thus pointing out the cognitive alterations in this model. In the MWM and in the BM, spatial learning performance but also short-term spatial memory were altered in CORT-treated mice. In the MWM, unlike control animals, CORT-treated animals failed to learn a new location during the reversal phase, suggesting a loss of cognitive flexibility. Finally, in the BM, the lack of preference for the target quadrant during the recall probe trial in animals receiving corticosterone regimen demonstrates that long-term retention was also affected in this paradigm. Taken together, our results highlight that CORT-induced anxio-depressive-like phenotype is associated with a cognitive deficit affecting all aspects of memory tested.

  5. 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…

  6. Depression and Suicidality

    ERIC Educational Resources Information Center

    Leonard, C. V.

    1974-01-01

    Suicidality ratings for 90 patients in a voluntary psychiatric hospital ward are correlated with five possible indices of depression: self-ratings of depression, Minnesota Multiphasic Personality Inventory Depression scale scores, depressive diagnosis, and alcohol and drug use. Both depression and suicidality emerges in the factor structure as…

  7. [Fatigue and depression].

    PubMed

    Hell, Daniel

    2015-04-22

    Fatigue is characterised in an overview of the literature as a specific phenomenon of depression. Its differential diagnosis is discussed. Distinctions and correspondences to burnout are elaborated. Fatigue is not an obligatory symptom of depressive episodes, although it can contribute to depressive developments. The importance of fatigue in depressive episodes and its therapy is shown with the help of a circular model of depression.

  8. Illness perceptions associated with perinatal depression treatment use.

    PubMed

    O'Mahen, Heather A; Flynn, Heather A; Chermack, Stephen; Marcus, Sheila

    2009-12-01

    The relationship between psychological beliefs about depression and depression treatment use was examined in depressed pregnant and postpartum women using the Common Sense Model as a framework (CSM; Leventhal H, Nerenz DR, Steele DF (1984) A handbook of psychology and health illness representations and coping with health threats. Hillsdale, NJ: Erlbaum.). Pregnant women who screened >/ 10 on the Edinburgh Postnatal Depression Scale (EPDS; Cox et al. Br J Psychiatry 150:782-786, 1987) completed measures of depression symptoms, perceptions and treatment at three time points through 6 weeks postpartum. Understanding modifiable beliefs may be useful in improving low rates of perinatal depression treatment use. PMID:19471852

  9. Pleasant events, unpleasant events, and depression.

    PubMed

    Sweeney, P D; Shaeffer, D E; Golin, S

    1982-07-01

    A review of previous research on Lewinsohn's model of depression shows that the causal link between a lack of response-contingent positive reinforcement and subsequent depression remains unsubstantiated. The present study was designed to explicitly test this causal relationship through the use of cross-lagged panel correlation. Measures of depression and pleasant events were taken at two different points in time separated by 1 month. The results revealed that the null hypothesis of spuriousness could not be rejected, indicating the relation often found between a lack of pleasant events and depression is probably due to some unmeasured third variable. The results also indicated that there is no causal relation between unpleasant events and depression. In summary, the causal assumptions in Lewinsohn's theory of depression were not supported by the data. Possible third-variable explanations of the data and their implications are discussed.

  10. Freezing tolerance of winter wheat as influenced by extended growth at low temperature and exposure to freeze-thaw cycles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As the seasons progress, autumn-planted winter wheat plants (Triticum aestivum L.) first gain, then progressively lose freezing tolerance. Exposing the plants to freeze-thaw cycles of -3/3°C results in increased ability to tolerate subsequent freezing to potentially damaging temperatures. This stu...

  11. Mass production of shaped particles through vortex ring freezing

    NASA Astrophysics Data System (ADS)

    An, Duo; Warning, Alex; Yancey, Kenneth G.; Chang, Chun-Ti; Kern, Vanessa R.; Datta, Ashim K.; Steen, Paul H.; Luo, Dan; Ma, Minglin

    2016-08-01

    A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be `frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials.

  12. 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.

  13. Mass production of shaped particles through vortex ring freezing.

    PubMed

    An, Duo; Warning, Alex; Yancey, Kenneth G; Chang, Chun-Ti; Kern, Vanessa R; Datta, Ashim K; Steen, Paul H; Luo, Dan; Ma, Minglin

    2016-01-01

    A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be 'frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials.

  14. 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

  15. 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 ...

  16. Dehydration tolerance in wood frogs: a new perspective on development of amphibian freeze tolerance.

    PubMed

    Churchill, T A; Storey, K B

    1993-12-01

    Wood frogs, Rana sylvatica, tolerate the loss of 50-60% of total body water during experimental dehydration. The rate of water loss for unprotected frogs is the same whether animals are frozen (at -2 degrees C) or unfrozen (at 1 degrees C) but is greatly reduced when frogs are frozen under a protective layer of moss. Dehydrational death could occur in as little as 7-9 days for unprotected animals; this indicates the importance for winter survival of selecting well-protected and damp hibernation sites. Prior dehydration affected the cooling and freezing properties of frogs, reducing supercooling point and the amount of ice formed after 24 h at -2 degrees C and acting synergistically with freezing exposure in stimulating cryoprotectant synthesis. Analysis of the effects of controlled dehydration at 5 degrees C showed that changes in body water content alone (without freezing) stimulated liver glycogenolysis and the export of high concentrations of glucose into blood and other organs. Autumn-collected frogs dehydrated to 50% of total body water lost showed glucose levels of 165-1,409 nmol/mg protein in different organs, increases of 9- to 313-fold compared with control values and reaching final levels very similar to those induced by freezing exposure. The data support the proposal that various adaptations for natural freeze tolerance may have been derived from preexisting mechanisms for dealing with water stress in amphibians and that cell volume change may be one of the signals involved in triggering and sustaining molecular adaptations (e.g., cryoprotectant output) that support freezing survival.

  17. Social egg freezing: for better, not for worse.

    PubMed

    Mertes, Heidi; Pennings, Guido

    2011-12-01

    The possibility for healthy women to cryopreserve their oocytes in order to counter future infertility has gained momentum in recent years. However, women tend to cryopreserve oocytes at an age that is suboptimal from a clinical point of view--in their late thirties--when both oocyte quantity and quality have already considerably diminished and success rates for eventually establishing a pregnancy are thus limited. This also gives rise to ethical concerns, as the procedure is seen as giving false hope to (reproductively speaking) older women. This study evaluates which measures can be taken to turn social freezing into a procedure that is both clinically and ethically better than the current practice. The main objective of these measures is to convince those women who are most likely to (want to) reproduce at an above-average age to cryopreserve their oocytes at a time when this intervention is still likely to lead to a live birth and to discourage fertility clinics from specifically targeting women who have already surpassed the age at which good results can be expected. The possibility for healthy women to cryopreserve their oocytes in order to counter future infertility has gained momentum in recent years. However, women tend to cryopreserve oocytes at a time that is suboptimal from a clinical point of view - in their late thirties - when both oocyte quantity and quality have already considerably diminished and success rates for eventually establishing a pregnancy are thus limited. This also gives rise to ethical concerns, as the procedure is seen as giving false hope to (reproductively speaking) older women. We evaluate which measures can be taken to turn social freezing into a procedure that is both clinically and ethically better than the current practice and discern three different steps: creating public awareness; offering individualized, age-specific information and counselling; and offering predictive tests such as anti-Müllerian hormone measurements or

  18. Freezing in relaxor ferroelectrics and dipolar glasses

    NASA Astrophysics Data System (ADS)

    Pirc, Raša; Kutnjak, Zdravko

    2015-03-01

    A recently proposed semi-phenomenological model of freezing in relaxor ferroelectrics, based on the concept of polar nanoregions (PNRs) embedded in a polarizable medium, is reviewed. A generalized Landau-type free energy for the medium is discussed, where the medium polarization couples linearly to the PNR polarization. When the fourth-order Landau coefficient is negative (b < 0), the correlation radius rc, which measures the PNR size, depends on the temperature T and the applied field E. As T is lowered or E increased, rc increases and the volume of a cluster of PNRs grows until the percolation limit is reached. This leads to a generalized expression for the Vogel-Fulcher (VF) relaxation time with a field-dependent VF freezing temperature T0(E). The case b > 0, in which the percolation mechanism cannot be realized, is considered to be appropriate for dipolar glasses.

  19. 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.

  20. [Depressive symptoms and sexuality].

    PubMed

    Porto, Robert

    2014-10-01

    The mutually reinforcing dyad of depressive symptoms and erectile dysfunction is scientifically established. The cure of depression improves sexual dysfunction (SD) and the treatment of SD induces improvement of depression. Most of anti-depressants induce negative sexual side effects that lead to non-compliance of these treatments. The knowledge of interrelation between depression, anti-depressants and sexuality is of great importance in clinical practice.

  1. The effect of undissolved air on isochoric freezing.

    PubMed

    Perez, Pedro A; Preciado, Jessica; Carlson, Gary; DeLonzor, Russ; Rubinsky, Boris

    2016-06-01

    This study evaluates the effect of undissolved air on isochoric freezing of aqueous solutions. Isochoric freezing is concerned with freezing in a constant volume thermodynamic system. A possible advantage of the process is that it substantially reduces the percentage of ice in the system at every subzero temperature, relative to atmospheric freezing. At the pressures generated by isochoric freezing, or high pressure isobaric freezing, air cannot be considered an incompressible substance and the presence of undissolved air substantially increases the amount of ice that forms at any subfreezing temperature. This effect is measurable at air volumes as low as 1%. Therefore eliminating the undissolved air, or any separate gaseous phase, from the system is essential for retaining the properties of isochoric freezing. PMID:27074589

  2. The effect of undissolved air on isochoric freezing.

    PubMed

    Perez, Pedro A; Preciado, Jessica; Carlson, Gary; DeLonzor, Russ; Rubinsky, Boris

    2016-06-01

    This study evaluates the effect of undissolved air on isochoric freezing of aqueous solutions. Isochoric freezing is concerned with freezing in a constant volume thermodynamic system. A possible advantage of the process is that it substantially reduces the percentage of ice in the system at every subzero temperature, relative to atmospheric freezing. At the pressures generated by isochoric freezing, or high pressure isobaric freezing, air cannot be considered an incompressible substance and the presence of undissolved air substantially increases the amount of ice that forms at any subfreezing temperature. This effect is measurable at air volumes as low as 1%. Therefore eliminating the undissolved air, or any separate gaseous phase, from the system is essential for retaining the properties of isochoric freezing.

  3. Kinetic density functional theory of freezing.

    PubMed

    Baskaran, Arvind; Baskaran, Aparna; Lowengrub, John

    2014-11-01

    A theory of freezing of a dense hard sphere gas is presented. Starting from a revised Enskog theory, hydrodynamic equations that account for non-local variations in the density but local variations in the flow field are derived using a modified Chapman Enskog procedure. These hydrodynamic equations, which retain structural correlations, are shown to be effectively a time dependent density functional theory. The ability of this theory to capture the solid liquid phase transition is established through analysis and numerical simulations.

  4. An Improved Cryogen for Plunge Freezing

    PubMed Central

    Tivol, William F.; Briegel, Ariane; Jensen, Grant J.

    2011-01-01

    The use of an alkane mixture that remains liquid at 77 K to freeze specimens has advantages over the use of a pure alkane that is solid at 77 K. It was found that a mixture of methane and ethane did not give a cooling rate adequate to produce vitreous ice, but a mixture of propane and ethane did result in vitreous ice. Furthermore, the latter mixture produced less damage to specimens mounted on a very thin, fragile holey carbon substrate. PMID:18793481

  5. Ground freezing in tunnels: Three unusual applications

    NASA Astrophysics Data System (ADS)

    Maishman, D.; Powers, J. P.

    The three case histories described herein illustrate the broad versatility of the ground freezing method in solving tunneling problems. It is possible to construct various types of underground structures of frozen earth, to cutoff water and to support loads. These case histories illustrate a horizontal cylinder, an arch, and a bulkhead, all of frozen earth. Other shapes are possible, their variety limited only by the ingenuity of the designer.

  6. Atmospheric freeze drying assisted by power ultrasound

    NASA Astrophysics Data System (ADS)

    Santacatalina, J. V.; Cárcel, J. A.; Simal, S.; Garcia-Perez, J. V.; Mulet, A.

    2012-12-01

    Atmospheric freeze drying (AFD) is considered an alternative to vacuum freeze drying to keep the quality of fresh product. AFD allows continuous drying reducing fix and operating costs, but presents, as main disadvantage, a long drying time required. The application of power ultrasound (US) can accelerate AFD process. The main objective of the present study was to evaluate the application of power ultrasound to improve atmospheric freeze drying of carrot. For that purpose, AFD experiments were carried out with carrot cubes (10 mm side) at constant air velocity (2 ms-1), temperature (-10°C) and relative humidity (10%) with (20.5 kWm-3,USAFD) and without (AFD) ultrasonic application. A diffusion model was used in order to quantify the influence of US in drying kinetics. To evaluate the quality of dry products, rehydration capacity and textural properties were determined. The US application during AFD of carrot involved the increase of drying rate. The effective moisture diffusivity identified in USAFD was 73% higher than in AFD experiments. On the other hand, the rehydration capacity was higher in USAFD than in AFD and the hardness of dried samples did not show significant (p<0.05) differences. Therefore, US application during AFD significantly (p<0.05) sped-up the drying process preserving the quality properties of the dry product.

  7. Do supercooled liquids freeze by spinodal decomposition?

    PubMed

    Bartell, Lawrence S; Wu, David T

    2007-11-01

    Two questions are addressed in this paper: Is it likely that spinodals occur in the freezing of one-component liquids at degrees of supercooling as moderate as T/T melt=0.6, and are the ramified solidlike structural fluctuations seen in simulations of supercooled liquids the tell-tale harbingers of spinodal decomposition? It has been suggested in several papers that in the freezing of argonlike systems, a spinodal can be expected to be encountered at T/T melt of approximately 0.6 or even at a shallower degree of supercooling. Heuristic evidence, particularly that found in molecular dynamics simulations in the system of selenium hexafluoride, a substance with properties similar in several respects to those of argon, suggests that a spinodal does not occur at supercoolings even considerably deeper than T/T melt=0.6. Reinforcing this conclusion are arguments based on nucleation kinetics in the Appendix. It has been found that many of the very thin, ramified solidlike fluctuations encountered in simulations of deeply supercooled liquids do not, in themselves, qualify as true nuclei for freezing but do, nevertheless, significantly influence the properties of the liquids. They contribute to the breakdown of the Stokes-Einstein relation universally found in supercooled liquids, liquids which have not been seen to exhibit a spinodal. Although such ramified fluctuations have been postulated to be precursors of spinodal decomposition, that role has not yet been confirmed. PMID:17994827

  8. 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.

  9. 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.

  10. Fundamental technical elements of freeze-fracture/freeze-etch in biological electron microscopy.

    PubMed

    Carson, Johnny L

    2014-01-01

    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 ultrarapid freezing rates, often in the presence of cryoprotective agents to limit ice crystal formation, with subsequent fracturing of the specimen at liquid nitrogen cooled temperatures under high vacuum. The resultant fractured surface is replicated and stabilized by evaporation of carbon and platinum from an angle that confers surface three-dimensional detail to the cast. This technique has proved particularly enlightening for the investigation of cell membranes and their specializations and has contributed considerably to the understanding of cellular form to related cell function. In this report, we survey the instrument requirements and technical protocol for performing freeze-fracture, the associated nomenclature and characteristics of fracture planes, variations on the conventional procedure, and criteria for interpretation of freeze-fracture images. This technique has been widely used for ultrastructural investigation in many areas of cell biology and holds promise as an emerging imaging technique for molecular, nanotechnology, and materials science studies. PMID:25285532

  11. 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.

  12. 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.

  13. Understanding the freezing of biopharmaceuticals: first-principle modeling of the process and evaluation of its effect on product quality.

    PubMed

    Radmanovic, Nikola; Serno, Tim; Joerg, Susanne; Germershaus, Oliver

    2013-08-01

    Freezing and thawing are important process steps in the manufacture of numerous biopharmaceuticals. It is well established that these process steps can significantly influence product quality attributes (PQA). Herein, we describe a physico-mathematical model to predict product temperature profiles based on the freezing program as input parameter in a commercial freeze-thaw module. Applying this model, the time from first nucleation until the last point to freeze (LPF) reaching -5°C and the time from -5°C at LPF to -30°C at LPF was varied to study the effect on PQA in a full factorial design. Effects of process parameter settings on a typical fully formulated, highly concentrated monoclonal antibody (mAb) solution as well as highly concentrated mAb solution formulated with buffer only were investigated. We found that both process phases affected PQA, such as aggregates by size-exclusion chromatography, polydispersity index by dynamic light scattering, and number of subvisible particles and turbidity in a complex way. In general, intermediate cooling and freezing times resulted in overall optimized PQA. Fully formulated mAb solution containing cryoprotectant and nonionic surfactant was significantly less affected by freezing-thawing than mAb solution formulated in buffer only.

  14. Postpartum depression

    PubMed Central

    Pearlstein, Teri; Howard, Margaret; Salisbury, Amy; Zlotnick, Caron

    2014-01-01

    Postpartum depression (PPD) affects up to 15% of mothers. Recent research has identified several psychosocial and biologic risk factors for PPD. The negative short-term and long-term effects on child development are well-established. PPD is under recognized and under treated. The obstetrician and pediatrician can serve important roles in screening for and treating PPD. Treatment options include psychotherapy and antidepressant medication. Obstacles to compliance with treatment recommendations include access to psychotherapists and concerns of breastfeeding mothers about exposure of the infant to antidepressant medication. Further research is needed to examine systematically the short-term and long-term effect of medication exposure through breastmilk on infant and child development. PMID:19318144

  15. 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

  16. 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

  17. Cartilage ultrastructure after high pressure freezing, freeze substitution, and low temperature embedding. II. Intercellular matrix ultrastructure - preservation of proteoglycans in their native state

    PubMed Central

    1984-01-01

    The extracellular matrix of epiphyseal cartilage tissue was preserved in a state believed to resemble closely that of native tissue following processing by high pressure freezing, freeze substitution, and low temperature embedding (HPF/FS). Proteoglycans (PG) were preserved in an extended state and were apparent as a reticulum of fine filamentous threads throughout the matrix. Within this network, two morphologically discrete components were discernible and identified with the carbohydrate and protein components of PG molecules. Numerous points of contact were clearly visible between components of the PG network and cross-sectioned collagen fibrils and also between PG components and chondrocytic plasmalemmata. These observations provide direct morphological indication that such relationships may exist in native epiphyseal cartilage tissue. PMID:6707091

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  19. Magnetic Shift of the Chemical Freeze-out and Electric Charge Fluctuations.

    PubMed

    Fukushima, Kenji; Hidaka, Yoshimasa

    2016-09-01

    We discuss the effect of a strong magnetic field on the chemical freeze-out points in ultrarelativistic heavy-ion collisions. As a result of inverse magnetic catalysis or magnetic inhibition, the crossover onset to hot and dense matter out of quarks and gluons should be shifted to a lower temperature. To quantify this shift we employ the hadron resonance gas model and an empirical condition for the chemical freeze-out. We point out that the charged particle abundances are significantly affected by the magnetic field so that the electric charge fluctuation is largely enhanced, especially at high baryon density. The charge conservation partially cancels the enhancement, but our calculation shows that the electric charge fluctuation could serve as a magnetometer. We find that the fluctuation exhibits a crossover behavior rapidly increased for eB≳(0.4  GeV)^{2}, while the charge chemical potential has smoother behavior with an increasing magnetic field. PMID:27636469

  20. Magnetic Shift of the Chemical Freeze-out and Electric Charge Fluctuations

    NASA Astrophysics Data System (ADS)

    Fukushima, Kenji; Hidaka, Yoshimasa

    2016-09-01

    We discuss the effect of a strong magnetic field on the chemical freeze-out points in ultrarelativistic heavy-ion collisions. As a result of inverse magnetic catalysis or magnetic inhibition, the crossover onset to hot and dense matter out of quarks and gluons should be shifted to a lower temperature. To quantify this shift we employ the hadron resonance gas model and an empirical condition for the chemical freeze-out. We point out that the charged particle abundances are significantly affected by the magnetic field so that the electric charge fluctuation is largely enhanced, especially at high baryon density. The charge conservation partially cancels the enhancement, but our calculation shows that the electric charge fluctuation could serve as a magnetometer. We find that the fluctuation exhibits a crossover behavior rapidly increased for e B ≳(0.4 GeV )2, while the charge chemical potential has smoother behavior with an increasing magnetic field.

  1. 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

  2. Comparing contact and immersion freezing from continuous flow diffusion chambers

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Ice nucleating particles (INPs) in the atmosphere are responsible for glaciating cloud droplets between 237 and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. To date, direct comparisons of contact and immersion freezing with the same INP, for similar residence times and concentrations, are lacking. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data were obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH) using 80 µm diameter droplets, which can interact with INPs for residence times of 2 and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter Arizona Test Dust (ATD) and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm-3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm-3 for AgI. For concentrations < 5000 cm-3, the droplets collect only one particle on average during their time in the chamber. For ATD and kaolinite particles, contact freezing efficiencies at 2 s residence time were smaller than at 4 s, which is in disagreement with a collisional contact freezing process but in accordance with immersion freezing or adhesion freezing. With "adhesion freezing", we refer to a contact nucleation process that is enhanced compared to immersion freezing

  3. 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

  4. The WAG/Rij strain: a genetic animal model of absence epilepsy with comorbidity of depression [corrected].

    PubMed

    Sarkisova, Karine; van Luijtelaar, Gilles

    2011-06-01

    A great number of clinical observations show a relationship between epilepsy and depression. Idiopathic generalized epilepsy, including absence epilepsy, has a genetic basis. The review provides evidence that WAG/Rij rats can be regarded as a valid genetic animal model of absence epilepsy with comorbidity of depression. WAG/Rij rats, originally developed as an animal model of human absence epilepsy, share many EEG and behavioral characteristics resembling absence epilepsy in humans, including the similarity of action of various antiepileptic drugs. Behavioral studies indicate that WAG/Rij rats exhibit depression-like symptoms: decreased investigative activity in the open field test, increased immobility in the forced swimming test, and decreased sucrose consumption and preference (anhedonia). In addition, WAG/Rij rats adopt passive strategies in stressful situations, express some cognitive disturbances (reduced long-term memory), helplessness, and submissiveness, inability to make choice and overcome obstacles, which are typical for depressed patients. Elevated anxiety is not a characteristic (specific) feature of WAG/Rij rats; it is a characteristic for only a sub-strain of WAG/Rij rats susceptible to audiogenic seizures. Interestingly, WAG/Rij rats display a hyper-response to amphetamine similar to anhedonic depressed patients. WAG/Rij rats are sensitive only to chronic, but not acute, antidepressant treatments, suggesting that WAG/Rij rats fulfill a criterion of predictive validity for a putative animal model of depression. However, more and different antidepressant drugs still await evaluation. Depression-like behavioral symptoms in WAG/Rij rats are evident at baseline conditions, not exclusively after stress. Experiments with foot-shock stress do not point towards higher stress sensitivity at both behavioral and hormonal levels. However, freezing behavior (coping deficits) and blunted response of 5HT in the frontal cortex to uncontrollable sound stress

  5. 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.

  6. Freezing of molecular hydrogen and its isotopes in porous Vycor glass

    SciTech Connect

    Beaudoin, G.; Haljan, P.; Paetkau, M.; Beamish, J.R.

    1996-10-01

    The authors have made a detailed ultrasonic study of freezing and melting of molecular H{sub 2}, HD and D{sub 2} in the pores of Vycor glass. The behavior was similar to that seen in previous measurements with argon and helium. The hydrogen liquids undercooled about 2.5 K below their bulk triple points before freezing began and there was substantial hysteresis between freezing and melting. The velocity and attenuation began to increase suddenly at the onset of freezing. The velocity continued to increase to the lowest temperatures (2K) and the attenuation had a broad peak at about two thirds of the freezing temperature. The authors attribute these effects to stress relaxation via thermally activated vacancy motion in the solid hydrogen, an interpretation confirmed by looking at the frequency dependence of the velocity and attenuation. The magnitude of the velocity and attenuation changes increased in going from H{sub 2} to HD to D{sub 2}, as expected based on their increasing densities and elastic constants. However, there were no qualitative differences between the boson (H{sub 2} and D{sub 2}) and fermion (HD) cases nor, for that matter, between hydrogen and argon. The authors believe that essentially all the hydrogen was frozen a few tenths of a kelvin below T{sub F}, at the point where the melting;freezing hysteresis began. If even a few per cent of the hydrogen had remained liquid and become superfluid at some lower temperature, it would have been seen as a further increase in the velocity and a critical attenuation peak. The sensitivity of the ultrasonic measurements allowed the authors to make accurate measurements of the freezing and melting temperatures of the different liquids in Vycor. They found that the fractional undercooling, (T{sub B} {minus} T{sub F})/T{sub B}, increased as the molecular mass decreased which may indicate the importance of quantum effects on the liquid-solid interfacial energy {sigma}{sub Is}.

  7. Observations of Air-Ice and Air-Ocean Interactions During Arctic Freeze-Up

    NASA Astrophysics Data System (ADS)

    Persson, O. P. G.

    2015-12-01

    Surface energy fluxes are key to the annual summer melt and autumn freeze-up of Arctic sea ice, but are strongly modulated by interactions between atmospheric, ocean, and sea-ice processes. This presentation will examine direct observations of energy fluxes during autumn freeze-up from three recent field programs: the international Arctic Clouds in Summer Experiment (ACSE) on board the R/V Oden in 2014, the Japanese MR14-05 cruise of the R/V Mirai in 2014, and the ONR-funded Sea State cruise of the R/V Sikuliaq in 2015. The R/V Oden obtained measurements in open water and multi-year ice north of the New Siberian Islands, the R/V Mirai's measurements were at a fixed point near the ice edge in the western Canada Basin, and the measurements from the Sikuliaq were obtained at the advancing ice edge in the Canada Basin/Beaufort Sea. Though measurement types varied, all three cruises made atmospheric measurements with radiosondes and remote sensing at high temporal resolution, obtained measurements or estimates of all terms in the surface energy budget equation, obtained upper-ocean thermodynamic measurements with frequent CTDs, and were able to characterize the evolving air-ocean and air-ice interfaces. The 2014 cruises document processes producing autumnal heat loss in the upper ocean just before and at the very incipient stages of ice formation, while the third cruise documented processes responsible for ice formation during the main freeze-up period. Ocean freeze-up was observed when the near-surface ocean temperature had reached its freezing point and energy loss to the atmosphere continued (Fig. 1). This important loss of energy to the atmosphere from the ocean mixed layer was modulated by a number of local and regional atmospheric processes and some ocean processes, producing significant variability. The different energy budgets over the existing sea ice and adjacent open water also played a major role in the freeze-up processes. This presentation will attempt to

  8. An electrochemical in situ study of freezing and thawing of ionic liquids in carbon nanopores.

    PubMed

    Weingarth, Daniel; Drumm, Robert; Foelske-Schmitz, Annette; Kötz, Rüdiger; Presser, Volker

    2014-10-21

    Room temperature ionic liquids (RTILs) are an emerging class of electrolytes enabling high cell voltages and, in return, high energy density of advanced supercapacitors. Yet, the low temperature behavior, including freezing and thawing, is little understood when ions are confined in the narrow space of nanopores. This study shows that RTILs may show a tremendously different thermal behavior when comparing bulk with nanoconfined properties as a result of the increased surface energy of carbon pore walls. In particular, a continuous increase in viscosity is accompanied by slowed-down charge-discharge kinetics as seen with in situ electrochemical characterization. Freezing reversibly collapses the energy storage ability and thawing fully restores the initial energy density of the material. For the first time, a different thermal behavior in positively and negatively polarized electrodes is demonstrated. This leads to different freezing and melting points in the two electrodes. Compared to bulk, RTILs in the confinement of electrically charged nanopores show a high affinity for supercooling; that is, the electrode may freeze during heating. PMID:25201074

  9. Assessment of depression in medical patients: A systematic review of the utility of the Beck Depression Inventory-II

    PubMed Central

    Wang, Yuan-Pang; Gorenstein, Clarice

    2013-01-01

    To perform a systematic review of the utility of the Beck Depression Inventory for detecting depression in medical settings, this article focuses on the revised version of the scale (Beck Depression Inventory-II), which was reformulated according to the DSM-IV criteria for major depression. We examined relevant investigations with the Beck Depression Inventory-II for measuring depression in medical settings to provide guidelines for practicing clinicians. Considering the inclusion and exclusion criteria seventy articles were retained. Validation studies of the Beck Depression Inventory-II, in both primary care and hospital settings, were found for clinics of cardiology, neurology, obstetrics, brain injury, nephrology, chronic pain, chronic fatigue, oncology, and infectious disease. The Beck Depression Inventory-II showed high reliability and good correlation with measures of depression and anxiety. Its threshold for detecting depression varied according to the type of patients, suggesting the need for adjusted cut-off points. The somatic and cognitive-affective dimension described the latent structure of the instrument. The Beck Depression Inventory-II can be easily adapted in most clinical conditions for detecting major depression and recommending an appropriate intervention. Although this scale represents a sound path for detecting depression in patients with medical conditions, the clinician should seek evidence for how to interpret the score before using the Beck Depression Inventory-II to make clinical decisions. PMID:24141845

  10. Factors that influence freezing in the sub-Antarctic springtail Tullbergia antarctica.

    PubMed

    Worland, M Roger

    2005-08-01

    Effects of 12 biotic and abiotic factors on the freezing point of the sub-Antarctic springtail, Tullbergia antarctica, were investigated. Repeated cooling of individual springtails five times resulted in very similar freezing points suggesting that ice nucleation in this freeze-susceptible species is likely to be initiated by intrinsic factors rather than being a stochastic event. Mean supercooling point (SCP) was influenced by cooling protocol, showing a linear increase in mean SCP with cooling rates from 8 to 0.1 degrees Cmin(-1). However, the opposite effect (decreasing SCP) was seen with slower cooling. Slower rates may be ecologically realistic and allow time for appropriate physiological and biochemical changes. Feeding and food presence in the gut had no effect on SCP, and there was no correlation between the ice nucleating activity of bacteria isolated from the guts and the whole springtail SCP. Habitat altitude and diurnal light and temperature regimes also had no effect on SCP. There was no correlation between the cryoprotectant concentration of fresh animals and their SCP, but experimental desiccation resulted in increased osmolality and decreased SCP, although with considerable individual variation. The most significant influence on SCP was associated with ecdysis. As springtails cease feeding for a period either side of ecdysis, shedding the entire gut lining, moulting may be an efficient mechanism of clearing the gut of all ice nucleating material. This previously unrecognised relationship between ecdysis, cold tolerance and seasonal survival tactics may play an important role in over-winter survival of some arthropods. PMID:15936029

  11. Factors that influence freezing in the sub-Antarctic springtail Tullbergia antarctica.

    PubMed

    Worland, M Roger

    2005-08-01

    Effects of 12 biotic and abiotic factors on the freezing point of the sub-Antarctic springtail, Tullbergia antarctica, were investigated. Repeated cooling of individual springtails five times resulted in very similar freezing points suggesting that ice nucleation in this freeze-susceptible species is likely to be initiated by intrinsic factors rather than being a stochastic event. Mean supercooling point (SCP) was influenced by cooling protocol, showing a linear increase in mean SCP with cooling rates from 8 to 0.1 degrees Cmin(-1). However, the opposite effect (decreasing SCP) was seen with slower cooling. Slower rates may be ecologically realistic and allow time for appropriate physiological and biochemical changes. Feeding and food presence in the gut had no effect on SCP, and there was no correlation between the ice nucleating activity of bacteria isolated from the guts and the whole springtail SCP. Habitat altitude and diurnal light and temperature regimes also had no effect on SCP. There was no correlation between the cryoprotectant concentration of fresh animals and their SCP, but experimental desiccation resulted in increased osmolality and decreased SCP, although with considerable individual variation. The most significant influence on SCP was associated with ecdysis. As springtails cease feeding for a period either side of ecdysis, shedding the entire gut lining, moulting may be an efficient mechanism of clearing the gut of all ice nucleating material. This previously unrecognised relationship between ecdysis, cold tolerance and seasonal survival tactics may play an important role in over-winter survival of some arthropods.

  12. Depression in Cognitive Impairment

    PubMed Central

    Pellegrino, Laurel D.; Lyketsos, Constantine G.; Marano, Christopher M.

    2014-01-01

    Depression and cognitive disorders, including dementia and mild cognitive impairment, are common in the elderly. Depression is also a common feature of cognitive impairment although the symptoms of depression in cognitive impairment differ from depression without cognitive impairment. Pre-morbid depression approximately doubles the risk of subsequent dementia. There are two predominant, though not mutually exclusive, constructs linking pre-morbid depression to subsequent cognitive impairment: Alzheimer’s pathology and the vascular depression hypothesis. When evaluating a patient with depression and cognitive impairment, it is important to obtain caregiver input and to evaluate for alternative etiologies for depressive symptoms such as delirium. We recommend a sequential approach to the treatment of depression in dementia patients: (1) a period of watchful waiting for milder symptoms, (2) psychosocial treatment program, (3) a medication trial for more severe symptoms or failure of psychosocial interventions, and (4) possible ECT for refractory symptoms. PMID:23933974

  13. Multifractality and freezing phenomena in random energy landscapes: An introduction

    NASA Astrophysics Data System (ADS)

    Fyodorov, Yan V.

    2010-10-01

    We start our lectures with introducing and discussing the general notion of multifractality spectrum for random measures on lattices, and how it can be probed using moments of that measure. Then we show that the Boltzmann-Gibbs probability distributions generated by logarithmically correlated random potentials provide a simple yet non-trivial example of disorder-induced multifractal measures. The typical values of the multifractality exponents can be extracted from calculating the free energy of the associated Statistical Mechanics problem. To succeed in such a calculation we introduce and discuss in some detail two analytically tractable models for logarithmically correlated potentials. The first model uses a special definition of distances between points in space and is based on the idea of multiplicative cascades which originated in theory of turbulent motion. It is essentially equivalent to statistical mechanics of directed polymers on disordered trees studied long ago by Derrida and Spohn (1988) in Ref. [12]. In this way we introduce the notion of the freezing transition which is identified with an abrupt change in the multifractality spectrum. Second model which allows for explicit analytical evaluation of the free energy is the infinite-dimensional version of the problem which can be solved by employing the replica trick. In particular, the latter version allows one to identify the freezing phenomenon with a mechanism of the replica symmetry breaking (RSB) and to elucidate its physical meaning. The corresponding one-step RSB solution turns out to be marginally stable everywhere in the low-temperature phase. We finish with a short discussion of recent developments and extensions of models with logarithmic correlations, in particular in the context of extreme value statistics. The first appendix summarizes the standard elementary information about Gaussian integrals and related subjects, and introduces the notion of the Gaussian free field characterized by

  14. Freezing of water saturated in aluminum wool mats

    NASA Astrophysics Data System (ADS)

    Sugawara, M.; Onodera, T.; Komatsu, Y.; Tago, M.; Beer, H.

    2008-05-01

    This paper is concerned with the freezing of water saturated in aluminum wool mats (AWM) around a cooling pipe. Two arrangements of AWM around the pipe are considered, i.e. a disk-type and a roll-type. Freezing mass M(kg/m2) in the disk type for a porosity ɛ = 0.95, indicates to be two times larger compared with that without AWM (i.e. ɛ = 1) at the freezing time t = 180 min. Even a small AWM volume fraction enhances considerably freezing of water in the disk type. However, freezing enhancement in the roll type is small compared with that of the disk type. Numerical calculation predicts well freezing at the disk type arrangement by using an anisotropy model for the effective thermal conductivity of ice/water saturated AWM, however, poor predictions for the roll type arrangement.

  15. Dopamine, depression and antidepressants.

    PubMed

    Dailly, Eric; Chenu, Franck; Renard, Caroline E; Bourin, Michel

    2004-12-01

    Abstract The relationship between depression and dopamine deficiency in the mesolimbic pathway has been hypothesized for many years. The experimental studies with animal models of depression and the human studies implicate the role of the dopamine system in depression. Not only do dopaminergic receptor agonists, but also antagonists such as olanzapine exhibit antidepressant effects associated with standard antidepressants in patients with treatment-resistant depression. This paradoxical result suggests that further investigations are necessary to understand the role played by dopamine in depression.

  16. Immersion freezing of birch pollen washing water

    NASA Astrophysics Data System (ADS)

    Augustin, Stefanie; Hartmann, Susan; Pummer, Bernhard; Grothe, Hinrich; Niedermeier, Dennis; Clauss, Tina; Voigtländer, Jens; Tomsche, Laura; Wex, Heike; Stratmann, Frank

    2013-04-01

    Up to now, the importance of pollen for atmospheric ice nucleation was considered to be minor, as they are too large to stay in the atmosphere for a long time. But as recent investigations have shown, not the pollen grains themselves are responsible for freezing, but easily suspendable macromolecules on their surfaces (Pummer et al., 2012). Due to the bursting of pollen grains these ice nucleating active (INA) macromolecules could be numerous in the atmosphere. In the present study, the immersion freezing behavior of birch pollen, i.e. its ice nucleating active (INA) macromolecules, was investigated at the Leipzig Aerosol Cloud Interaction Simulator (LACIS, Hartmann et al., 2011). For this, washing water of two different birch pollen samples with different origin (Northern birch and Southern birch) were used. Immersion freezing of droplets generated from the pollen washing water was observed at temperatures higher than -20 °C for both samples. The main difference between the Northern and the Southern birch pollen was the temperature dependence of the immersion freezing process. Our results suggest that the ice nucleating potential of the Southern birch is controlled by a single type of INA macromolecule, while the Northern birch pollen seem to feature two distinctively different types of INA macromolecules. We determined the heterogeneous nucleation rates for both INA macromolecule types and thereby consistently describe the ice nucleation behavior of both, the Southern and the Northern birch pollen washing water. Furthermore we will suggest a theoretical framework for describing e.g. single INA macromolecule related ice nucleation in atmospheric models. References: Pummer, B. G., Bauer, H., Bernardi, J., Bleicher, S. and Grothe, H.: Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen. Atmos. Chem. Phys., 12, 2541-2550, doi:10.5194/acp-12-2541-2012, 2012. Hartmann, S., Niedermeier, D., Voigtländer, J., Clauss, T

  17. 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.

  18. An improved high pressure freezing and freeze substitution method to preserve the labile vaccinia virus nucleocapsid.

    PubMed

    Jesus, Desyree Murta; Moussatche, Nissin; Condit, Richard C

    2016-07-01

    In recent years, high pressure freezing and freeze substitution have been widely used for electron microscopy to reveal viral and cellular structures that are difficult to preserve. Vaccinia virus, a member of the Poxviridae family, presents one of the most complex viral structures. The classical view of vaccinia virus structure consists of an envelope surrounding a biconcave core, with a lateral body in each concavity of the core. This classical view was challenged by Peters and Muller (1963), who demonstrated the presence of a folded tubular structure inside the virus core and stated the difficulty in visualizing this structure, possibly because it is labile and cannot be preserved by conventional sample preparation. Therefore, this tubular structure, now called the nucleocapsid, has been mostly neglected over the years. Earlier studies were able to preserve the nucleocapsid, but with low efficiency. In this study, we report the protocol (and troubleshooting) that resulted in preservation of the highest numbers of nucleocapsids in several independent preparations. Using this protocol, we were able to demonstrate an interdependence between the formation of the virus core wall and the nucleocapsid, leading to the hypothesis that an interaction exists between the major protein constituents of these compartments, A3 (core wall) and L4 (nucleocapsid). Our results show that high pressure freezing and freeze substitution can be used in more in-depth studies concerning the nucleocapsid structure and function.

  19. 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.

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

    PubMed Central

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

    1995-01-01

    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

  1. 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.

  2. 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.

  3. Does the cryogenic freezing process cause shorter telomeres?

    PubMed

    Jenkins, Edmund C; Ye, Lingling; Silverman, Wayne P

    2012-08-01

    We have observed evidence of increased telomere shortening in short-term T-lymphocyte cultures following freezing and thawing of the original inoculum obtained by ficoll-paque gradient centrifugation, compared to T-lymphocytes that were cultured immediately without freezing and thawing from the same blood sample from 3 female and 3 male adults. Because freezing may have similar effects on other cell types, and because telomere shortening may only manifest its effects after many years or decades, we suggest there is a pressing need for evaluation of the effects of freezing on any cells envisioned for clinical applications, including embryo implantation. PMID:22465657

  4. Associations among smoking, anhedonia, and reward learning in depression.

    PubMed

    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

    2014-09-01

    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.

  5. 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.

  6. Morphological study of endothelial cells during freezing

    NASA Astrophysics Data System (ADS)

    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.

  7. Effect of soil freezing on particulate resuspension

    SciTech Connect

    Duce, S.W.; Shaw, P.G.; Winberg, M.R.

    1988-08-01

    This report presents the results of small scale laboratory tests that were conducted to determine the effect of soil freezing on soil resuspension. Nontransuranic contaminated soil form the Radioactive Waste Management Complex was subjected to a series of test conditions to determine respirable and nonrespirable fractions of airborne dust. A separate fraction of the same soil was spiked with Pu-239 and subjected to the same test conditions. Concentrations of resuspended soil and Pu in air were determined. Test results show that: (a) the largest fraction of soil resuspended is in the nonrespirable size fraction, (b) the concentration of resuspended soil in air is highly dependent on surface air velocity, and (c) freezing is not as effective at reducing resuspension of fine dry soil as it is with coarse soil, and (d) artificially prepared Pu contaminated soil has a high proportion of the total activity distributed on ultrafine material, reacts inversely to the mass movement of soil, and does not adequately imitate Pu movement in an actual contaminated soil. 26 figs., 3 tabs.

  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. The structure of the winter troposphere during the catastrophically freezing rain (December 2010)

    NASA Astrophysics Data System (ADS)

    Sokolikhina, Elena; Sokolikhina, Natalia; Semenov, Evgeniy; Surkova, Galina

    2016-04-01

    The atmospheric circulation conditions above Moscow, which led to the unprecedented freezing rain and to the glazed ice of strong intensity, were examined. It was shown, that the freezing rain related with the active warm frontal zone, which was situated between the surface positions of the polar and arctic fronts. At the same time the surface temperature inversion (to the height of 1500-2000 m) was accompanied by the specific humidity inversion and by the dew-point deficit values less than 2 degrees Celsius. It was established, that together with the powerful advection of the warm and humid air on the frontal surface, the cold advection in the cold air mass above the front was observed. In other words, in the lower troposphere in the freezing rain zone, the double-layer advection was observed. As a result the air temperature at the ground surface was negative (-5…-7 degrees Celsius) during the freezing rain; and nearby the 850 hPa surface (1500 m) the temperature was positive (+2…+3 degrees Celsius). The sketchy evolution of the phase of the widespread precipitation of the warm front above Moscow can be represented in the following way: the snow (over 2000-2500 m) -> the rain (in the layer of the positive temperature on the altitude of 1000-2000 m) -> the glazed ice on the ground surface. The strong glazed ice (the thickness is about 20-30 mm), formed in the result of the freezing rain, was observed in the Moscow region during two weeks!

  10. 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

  11. 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 (0°C), constant freezing (-5°C) and fluctuating temperature (0 to -5°C) - 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 (-5°C) compared with thawed controls (0°C). 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

  12. The association between Diabetes mellitus and Depression

    PubMed Central

    Bădescu, SV; Tătaru, C; Kobylinska, L; Georgescu, EL; Zahiu, DM; Zăgrean, AM; Zăgrean, L

    2016-01-01

    Depression occurrence is two to three times higher in people with diabetes mellitus, the majority of the cases remaining under-diagnosed. The purpose of this review was to show the links between depression and diabetes, point out the importance of identifying depression in diabetic patients and identify the possible ways to address both diseases. Possible common pathophysiological mechanisms as stress and inflammation were explained, while emphasis was made on screening for depression in diabetic patients. An important aspect for the diabetic specialist would be the understanding of the common origins of diabetes and depression and the awareness of this quite common comorbidity, in order to improve the outcomes of both diseases. Abbreviations: DALYS = disability adjusted life years, DSM-5 = American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, DM1 = Type 1 diabetes mellitus, DM2 = Type 2 diabetes mellitus, HPA-axis = hypothalamus – pituitary – adrenal axis, SNS = sympathetic nervous system, BDI = Beck Depression Inventory, CES-D = Centre for Epidemiologic Studies Depression Scale, HADS = Hospital Anxiety and Depression Scale, PHQ = Patient Health Questionnaire. PMID:27453739

  13. Preparation of porous microcrystalline cellulose pellets by freeze-drying: effects of wetting liquid and initial freezing conditions.

    PubMed

    Balaxi, Maria; Nikolakakis, Ioannis; Malamataris, Stavros

    2010-04-01

    The effects of wetting liquid and initial freezing conditions on the pore volume and pore size distribution of freeze-dried microcrystalline cellulose (MCC) pellets were studied with mercury porosimetry. Freeze-drying was applied after extrusion/spheronization using two wetting liquids (water and water-isopropanol) and three initial freezing conditions (-30, 80, and -197 degrees C). Also, the effects of initial freezing were compared to those on pellets prepared with extraction of NaCl from Avicel(R)/NaCl pellets. Pellet porosity was found to increase with decreasing initial freezing temperature and the increase is greater for pellets made with water as wetting liquid. The mean pore diameter is greater for the extracted pellets, followed by nonextracted MCC pellets made with water and water-isopropanol. Also, the pore diameter is greater for freezing at -80 degrees C comparatively to that at -30 degrees C, while it is smaller for freezing at -197 degrees C. Narrower and more symmetrical pore size distributions were obtained with water-isopropanol at -197 degrees C. The higher porosity obtained with water alone and the smallest mean pore diameter and narrower distribution obtained with water-isopropanol may be due to the effects of H-bonding between isopropanol and water molecules on the nucleation and growth of ice crystals during the initial freezing. PMID:19894272

  14. 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

  15. Embolism formation during freezing in the wood of Picea abies.

    PubMed

    Mayr, Stefan; Cochard, Hervé; Améglio, Thierry; Kikuta, Silvia B

    2007-01-01

    Freeze-thaw events can cause embolism in plant xylem. According to classical theory, gas bubbles are formed during freezing and expand during thawing. Conifers have proved to be very resistant to freeze-thaw induced embolism, because bubbles in tracheids are small and redissolve during thawing. In contrast, increasing embolism rates upon consecutive freeze-thaw events were observed that cannot be explained by the classical mechanism. In this study, embolism formation during freeze-thaw events was analyzed via ultrasonic and Cryo-scanning electron microscope techniques. Twigs of Picea abies L. Karst. were subjected to up to 120 freeze-thaw cycles during which ultrasonic acoustic emissions, xylem temperature, and diameter variations were registered. In addition, the extent and cross-sectional pattern of embolism were analyzed with staining experiments and Cryo-scanning electron microscope observations. Embolism increased with the number of freeze-thaw events in twigs previously dehydrated to a water potential of -2.8 MPa. In these twigs, acoustic emissions were registered, while saturated twigs showed low, and totally dehydrated twigs showed no, acoustic activity. Acoustic emissions were detected only during the freezing process. This means that embolism was formed during freezing, which is in contradiction to the classical theory of freeze-thaw induced embolism. The clustered pattern of embolized tracheids in cross sections indicates that air spread from a dysfunctional tracheid to adjacent functional ones. We hypothesize that the low water potential of the growing ice front led to a decrease of the potential in nearby tracheids. This may result in freezing-induced air seeding.

  16. Validation studies of a computational model for molten material freezing

    SciTech Connect

    Sawada, Tetsuo; Ninokata, Hisashi; Shimizu, Akinao

    1996-02-01

    Validation studies are described of a computational model for the freezing of molten core materials under core disruptive accident conditions of fast breeder reactors. A series of out-of-pile experiments named SIMBATH, performed at Forschungszentrum Karlsruhe in Germany, has already been analyzed with the SIMMER-II code. In the current study, TRAN simulation tests in the SIMBATH facility are analyzed by SIMMER-II for its modeling validation of molten material freezing. The original TRAN experiments were performed at Sandia National laboratories to examine the freezing behavior of molten UO{sub 2} injected into an annular channels. In the TAN simulation experiments of the SIMBATH series, similar freezing phenomena are investigated for molten thermite, a mixture of Al{sub 2}O{sub 3} and iron, instead of UO{sub 2}. Two typical TRAN simulation tests are analyzed that aim at clarification of the applicability of the code to the freezing process during the experiments. The distribution of molten materials that are deposited in the test section according to the experimental measurements and in calculations by SIMMER-II is compared. These studies confirm that the conduction-limited freezing model combined with the rudimentary bulk freezing (particle-jamming) model of SIMMER-II is compared. These studies confirm that the conduction-limited freezing model combined with the rudimentary bulk freezing (particle-jamming) model of SIMMER-II could be used to reproduce the TRAN simulation experiments satisfactorily. This finding encourages the extrapolation of the results of previous validation research for SIMMER-II based on other SIMBATH tests to reactor case analyses. The calculation by SIMMER-II suggest that further improvements of the model, such as freezing on a convex surface of pin cladding and the scraping of crusts, make possible more accurate simulation of freezing phenomena.

  17. Improved representation of cell surface structures by freeze substitution and backscattered electron imaging.

    PubMed

    Walther, P; Hentschel, J

    1989-01-01

    A surface preparation method for the SEM based on cryofixation is presented suitable for the demonstration of membrane particles on whole cells. LLC-PK1 cells (a renal epithelial cell line in culture) were fast frozen, freeze substituted, critical point dried, shadowed with 2 nm of platinum carbon and stabilized with a carbon backing layer. Membrane bound particles are visualized by the material dependent backscattered electron image mainly originating from the platinum shadow. The surface of the LLC-PK1 cells is almost free of precipitated material indicating that the culture medium is removed during freeze substitution or critical point drying. The apical plasma membrane with microvilli and ciliae is well preserved and differences in particle density can be detected. The feasibility of the coating technique for backscattered electron imaging was tested on the well known hexagonally arranged intramembranous particles of fractured and partially freeze dried yeast. This 16.5 nm periodic structure is clearly demonstrable on the bulk SEM-specimen stablized with the carbon backing layer. Without a carbon layer severe shrinking artifacts occurred.

  18. Theory and experiments on the ice–water front propagation in droplets freezing on a subzero surface

    NASA Astrophysics Data System (ADS)

    Nauenberg, Michael

    2016-07-01

    An approximate theory is presented that describes the propagation of the ice–water front that develops in droplets of water that are deposited on a planar surface at a temperature below the melting point of ice. This theory is compared with experimental observation of the time evolution of this front. These experiments were performed by freezing water droplets directly on a block of dry ice, and to examine the effects of the thermal conductivity of a substrate during the freezing process. Such droplets were also deposited on a glass plate and on a copper plate placed on dry ice. The temperature at the base of these droplets, and the dependence of the freezing time on their size were also obtained experimentally, and compared with our analytic theory. These experiment can be readily performed by physics undergraduate students, and reveal that the usual assumption of constant temperature at the base of the droplets cannot be implemented in practice.

  19. Theory and experiments on the ice-water front propagation in droplets freezing on a subzero surface

    NASA Astrophysics Data System (ADS)

    Nauenberg, Michael

    2016-07-01

    An approximate theory is presented that describes the propagation of the ice-water front that develops in droplets of water that are deposited on a planar surface at a temperature below the melting point of ice. This theory is compared with experimental observation of the time evolution of this front. These experiments were performed by freezing water droplets directly on a block of dry ice, and to examine the effects of the thermal conductivity of a substrate during the freezing process. Such droplets were also deposited on a glass plate and on a copper plate placed on dry ice. The temperature at the base of these droplets, and the dependence of the freezing time on their size were also obtained experimentally, and compared with our analytic theory. These experiment can be readily performed by physics undergraduate students, and reveal that the usual assumption of constant temperature at the base of the droplets cannot be implemented in practice.

  20. Shrinkage of freeze-dried cryosections of cells: Investigations by EFTEM and cryo-CLEM.

    PubMed

    Casanova, G; Nolin, F; Wortham, L; Ploton, D; Banchet, V; Michel, J

    2016-09-01

    Freeze-drying of cryosections of cells or tissues is considered to be the most efficient preparation for microanalysis purpose related to transmission electron microscopy. It allows the measurements of ions and water contents at the ultrastructural level. However an important drawback is associated to freeze-drying: the shrinkage of the cryosections. The aim of this paper is the investigation of this phenomenon by means of three different methods applied to both hydrated and dehydrated cryosections: direct distance measurements on fiducial points, thickness measurements by energy filtered transmission microscopy (EFTEM) and cryo-correlative light electron microscopy (cryo-CLEM). Measurements in our experimental conditions reveal a lateral shrinkage around 10% but the most important result concerns the lack of differential shrinkage between most of the cellular compartments. PMID:27428286

  1. Shrinkage of freeze-dried cryosections of cells: Investigations by EFTEM and cryo-CLEM.

    PubMed

    Casanova, G; Nolin, F; Wortham, L; Ploton, D; Banchet, V; Michel, J

    2016-09-01

    Freeze-drying of cryosections of cells or tissues is considered to be the most efficient preparation for microanalysis purpose related to transmission electron microscopy. It allows the measurements of ions and water contents at the ultrastructural level. However an important drawback is associated to freeze-drying: the shrinkage of the cryosections. The aim of this paper is the investigation of this phenomenon by means of three different methods applied to both hydrated and dehydrated cryosections: direct distance measurements on fiducial points, thickness measurements by energy filtered transmission microscopy (EFTEM) and cryo-correlative light electron microscopy (cryo-CLEM). Measurements in our experimental conditions reveal a lateral shrinkage around 10% but the most important result concerns the lack of differential shrinkage between most of the cellular compartments.

  2. High quality FeSb2 single crystal growth by the gradient freeze technique

    NASA Astrophysics Data System (ADS)

    Cao, Yiming; Yuan, Shujuan; Liu, Ming; Kang, Baojuan; Lu, Bo; Zhang, Jincang; Cao, Shixun

    2013-01-01

    A single crystal of FeSb2 about 5 mm in diameter and 10 mm in length with a tapering spire was grown by the gradient freeze technique combining the Bridgman technique and flux method using Sb-rich melts in sealed quartz ampoules. X-ray powder diffraction pattern of single crystal FeSb2 indicates that it is a single phase marcasite structure. Clear Laue spots and scanning electron microscopy photographs indicate good quality and uniform of the FeSb2 single crystal. Magnetic susceptibility of FeSb2 along b-axis does not show the diamagnetic to paramagnetic crossover, indicating the intrinsic susceptibility of FeSb2 determined on large single crystals differs from that of the smaller samples prepared by other techniques. The new method of gradient freeze is of great significance for the single crystal growth of FeSb2 like materials with a peritectic point.

  3. 47 CFR 64.1190 - Preferred carrier freezes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 3 2014-10-01 2014-10-01 false Preferred carrier freezes. 64.1190 Section 64.1190 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) COMMON CARRIER SERVICES (CONTINUED) MISCELLANEOUS RULES RELATING TO COMMON CARRIERS Changes in Preferred Telecommunications Service Providers § 64.1190 Preferred carrier freezes....

  4. 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...

  5. 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.

  6. 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...

  7. 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

  8. 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...

  9. 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…

  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. 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

  12. [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

  13. Transition from baryon-to meson-dominated freeze-out—early decoupling around 30 A GeV?

    NASA Astrophysics Data System (ADS)

    Oeschler, H.; Cleymans, J.; Redlich, K.; Wheaton, S.

    2006-12-01

    The recently discovered sharp peak in the excitation function of the K+/π+ ratio around 30 A GeV in relativistic heavy-ion collisions is discussed in the framework of the statistical model. In this model, the freeze-out of an ideal hadron gas changes from a situation where baryons dominate to one with mainly mesons. This transition occurs at a temperature T = 140 MeV and a baryon chemical potential μB = 410 MeV corresponding to an energy of \\sqrt{s_NN} = 8.2\\,GeV . The calculated maximum in the K+/π+ ratio is, however, much less pronounced than that observed by the NA49 Collaboration. The smooth increase of the K-/π- ratio with incident energy and the shape of the excitation functions of the Λ/π+, Ξ-/π+ and Ω-/π+ ratios all exhibiting maxima at different incident energies is consistent with the presently available experimental data. The measured K+/π+ ratio exceeds the calculated one just at the incident energy when the freeze-out condition is changing. We speculate that at this point freeze-out might occur in a modified way. We discuss a scenario of an early freeze-out which indeed increases the K+/π+ ratio while most other particle ratios remain essentially unchanged. Such an early freeze-out is supported by results from HBT studies.

  14. [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.

  15. 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.

  16. Cooling system with automated seasonal freeze protection

    DOEpatents

    Campbell, Levi A.; Chu, Richard C.; David, Milnes P.; Ellsworth, Jr., Michael J.; Iyengar, Madhusudan K.; Simons, Robert E.; Singh, Prabjit; Zhang, Jing

    2016-05-24

    An automated multi-fluid cooling system and method are provided for cooling an electronic component(s). The cooling system includes a coolant loop, a coolant tank, multiple valves, and a controller. The coolant loop is at least partially exposed to outdoor ambient air temperature(s) during normal operation, and the coolant tank includes first and second reservoirs containing first and second fluids, respectively. The first fluid freezes at a lower temperature than the second, the second fluid has superior cooling properties compared with the first, and the two fluids are soluble. The multiple valves are controllable to selectively couple the first or second fluid into the coolant in the coolant loop, wherein the coolant includes at least the second fluid. The controller automatically controls the valves to vary first fluid concentration level in the coolant loop based on historical, current, or anticipated outdoor air ambient temperature(s) for a time of year.

  17. Cooling method with automated seasonal freeze protection

    DOEpatents

    Cambell, Levi; Chu, Richard; David, Milnes; Ellsworth, Jr, Michael; Iyengar, Madhusudan; Simons, Robert; Singh, Prabjit; Zhang, Jing

    2016-05-31

    An automated multi-fluid cooling method is provided for cooling an electronic component(s). The method includes obtaining a coolant loop, and providing a coolant tank, multiple valves, and a controller. The coolant loop is at least partially exposed to outdoor ambient air temperature(s) during normal operation, and the coolant tank includes first and second reservoirs containing first and second fluids, respectively. The first fluid freezes at a lower temperature than the second, the second fluid has superior cooling properties compared with the first, and the two fluids are soluble. The multiple valves are controllable to selectively couple the first or second fluid into the coolant in the coolant loop, wherein the coolant includes at least the second fluid. The controller automatically controls the valves to vary first fluid concentration level in the coolant loop based on historical, current, or anticipated outdoor air ambient temperature(s) for a time of year.

  18. 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.

  19. Ice adhesions in relation to freeze stress.

    PubMed

    Olien, C R; Smith, M N

    1977-10-01

    In freezing, competitive interaction between ice and hydrophilic plant substances causes an energy of adhesion to develop through the interstitial liquid. The thermodynamic basis for the adhesion energy is discussed, with estimates of the energies involved. In this research, effects of adhesion energy were observed microscopically in conjunction with energies of crystallization and frost desiccation. The complex character of ice in intact crown tissue of winter barley (Hordeum vulgare L.) and the problems of sectioning frozen tissue without producing artifacts led to an alternative study of single barley cells in a mesh of ice and cell wall polymers. Adhesions between ice, cell wall polymers, and the plasmalemma form a complexly interacting system in which the pattern of crystallization is a major factor in determination of stress and injury. PMID:16660124

  20. Learning about depression

    MedlinePlus

    ... once in a while. Clinical depression is a mood disorder. It occurs when feelings of sadness, loss, anger, ... Accessed October 31, 2014. Fava M, Cassano P. Mood disorders: Major depressive disorder and dysthymic disorder. In: Stern ...

  1. 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 ...

  2. Depression in the Workplace

    MedlinePlus

    ... on treatment for heart disease iv . The annual economic cost of depression in 1995 was $600 per ... Lowe SW, Berglund PA, Corey-Lisle PK. The economic burden of depression in the United States: how ...

  3. Older Adults and Depression

    MedlinePlus

    ... your depression or making it worse. Electroconvulsive therapy (ECT) is sometimes used for severe depression that is ... does not respond to medication or therapy. Although ECT once had a bad reputation, it has greatly ...

  4. 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 ...

  5. 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.

  6. 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.

  7. 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.

  8. Metal sandwich method to quick-freeze monolayer cultured cells for freeze-fracture.

    PubMed

    Fujimoto, T; Fujimoto, K

    1997-04-01

    We describe a simple quick-freezing method to obtain a large fractured plane of the plasma membrane from monolayer cultured cells. Cells were grown on thin gold foil, inverted on a thin layer of gelatin on thin copper foil, and frozen by a quick press between two gold-plated copper blocks precooled in liquid nitrogen. The frozen cell sandwich was mounted on the cold stage of a freeze-fracture device with the gold side up and was fractured by separating the sandwich with a cold fracture knife. When this technique was applied to confluent monolayer cells, large replicas of the E-face of the upper plasma membrane and the P-face of the lower plasma membrane were obtained. The present metal sandwich method is simple, does not require any expensive equipment, and provides a large fracture plane of the plasma membrane for subsequent histochemical manipulation. PMID:9111237

  9. 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.

  10. 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.

  11. Method of treating depression

    DOEpatents

    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.

  12. DEPRESSION IN WILSON'S DISEASE

    PubMed Central

    Pandey, R. S.; Swamy, H. S.; Sreenivas, K. N.; John, C. J.

    1981-01-01

    SUMMARY This study comprise of 23 patients of Wilson's Disease, who were assessed individually by a psychiatrist and neurologist separately. Clinically discernable psychiatric symptoms were detected in 11 patients. Depressed affect was the commonest finding in the series. While four out of five young patients showed depressive symptomatology, none of the six patients showed any depression. All four patients who had severely depressed affect were also patients who had most severe extrapyramidal features. PMID:22058523

  13. Freezing Precipitation and Freezing Events over Northern Eurasia and North America

    NASA Astrophysics Data System (ADS)

    Groisman, Pavel; Yin, Xungang; Bulygina, Olga; Partasenok, Irina; Zolina, Olga; Hanssen-Bauer, Inger

    2016-04-01

    With global climate change in the extratropics, the 0°C isotherm will not disappear and associated precipitation events will continue to occur. The near-0°C temperatures should generally move poleward and arrive at many locations earlier in spring or later in autumn. This could potentially affect the seasonal cycle of near-0°C precipitation. The overall warming, together with a larger influx of the water vapor in the winter atmosphere from the oceans (including ice-free portions of the Arctic Ocean) can also affect the amount of near-0°C precipitation. The issue of near 0°C precipitation is linked with several hazardous phenomena including heavy snowfall/rainfall transition around °C; strong blizzards; rain-on-snow events causing floods; freezing rain and freezing drizzle; and ice load on infrastructure. In our presentation using more than 1,500 long-term time series of synoptic observations for the past four decades, we present climatology and the empirical evidence about changes in occurrence, timing, and intensity of freezing rains and freezing drizzles over several countries of Northern Eurasia and North America. In the former Soviet Union, instrumental monitoring of ice load has been performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. Estimates of climatology and changes in ice load based on this monitoring at 958 Russian stations will be also presented. The work was supported by the Ministry of Education and Science of the Russian Federation (grant 14.B25.31.0026) and NASA LCLUC Program (grant "How Environmental Change in Central Asian Highlands Impacts High Elevation Communities").

  14. Effects of freezing rates and cryoprotectant on thermal expansion of articular cartilage during freezing process.

    PubMed

    Xu, Y; Sun, H J; Lv, Y; Zou, J C; Lin, B L; Hua, T C

    2013-01-01

    The intact articular cartilage has not yet been successfully preserved at low temperature most likely due to the volume expansion from water to ice during freezing. The objective of this current study focuses on examining thermal expansion behavior of articular cartilage (AC) during freezing from 0 degree C to -100 degree C. Thermo Mechanical Analysis (TMA) was used to investigate the effects of different concentrations of dimethyl sulphoxide (DMSO) (0%, 10%, 30% and 60% v/v) and different freezing rates (1 C/min, 3 C/min and 5 C/min). The results showed that: (1) the inhomogeneous thermal expansion (or contraction) presents due to inhomogeneous water distributions in articular cartilage during freezing, which also may be the most likely reason that the matrix has been damaged in cryopreserved intact articular cartilage; (2) at the phase transition temperature range, the maximum thermal strain change value for 5C/min is approximately 1.45 times than that for 1 C/min, but the maximum thermal expansion coefficient of the later is about six times than that of the former; (3) the thermal expansion coefficient decreases with increasing cooling rate at the unfrozen temperature region, but some opposite results are obtained at the frozen temperature region; (4) the higher the DMSO concentration is, at the phase change temperature region, the smaller the thermal strain change as well as the maximum thermal expansion coefficient are, but DMSO concentration exhibits little effect on the thermal expansion coefficient at both unfrozen and frozen region. Once the DMSO concentration increasing enough, e.g. 60% v/v, the thermal strain decreases linearly and smoothly without any abrupt change due to little or no ice crystal forms (i.e. vitrification) in frozen articular cartilage. This study may improve our understanding of the thermal expansion (or contraction) behavior of cryopreserved articular cartilage and it may be useful for the future study on cryopreservation of intact

  15. 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.

  16. Multiple glass transitions and freezing events of aqueous citric acid.

    PubMed

    Bogdan, Anatoli; Molina, Mario J; Tenhu, Heikki; Loerting, Thomas

    2015-05-14

    Calorimetric and optical cryo-microscope measurements of 10-64 wt % citric acid (CA) solutions subjected to moderate (3 K/min) and slow (0.5 and 0.1 K/min) cooling/warming rates and also to quenching/moderate warming between 320 and 133 K are presented. Depending on solution concentration and cooling rate, the obtained thermograms show one freezing event and from one to three liquid-glass transitions upon cooling and from one to six liquid-glass and reverse glass-liquid transitions, one or two freezing events, and one melting event upon warming of frozen/glassy CA/H2O. The multiple freezing events and glass transitions pertain to the mother CA/H2O solution itself and two freeze-concentrated solution regions, FCS1 and FCS2, of different concentrations. The FCS1 and FCS2 (or FCS22) are formed during the freezing of CA/H2O upon cooling and/or during the freezing upon warming of partly glassy or entirely glassy mother CA/H2O. The formation of two FCS1 and FCS22 regions during the freezing upon warming to our best knowledge has never been reported before. Using an optical cryo-microscope, we are able to observe the formation of a continuous ice framework (IF) and its morphology and reciprocal distribution of IF/(FCS1 + FCS2). Our results provide a new look at the freezing and glass transition behavior of aqueous solutions and can be used for the optimization of lyophilization and freezing of foods and biopharmaceutical formulations, among many other applications where freezing plays a crucial role.

  17. 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.

  18. Mesophyll freezing and effects of freeze dehydration visualized by simultaneous measurement of IDTA and differential imaging chlorophyll fluorescence.

    PubMed

    Hacker, Jürgen; Spindelböck, Joachim Paul; Neuner, Gilbert

    2008-11-01

    Infrared differential thermal analysis (IDTA) and differential imaging chlorophyll fluorescence (DIF) were employed simultaneously to study the two-dimensional pattern of ice propagation in leaves and mesophyll freeze dehydration as detected by a significant increase of basic chlorophyll fluorescence (F(0)). IDTA and DIF technique gave different insights into the freezing process of leaves that was highly species-specific. IDTA clearly visualized the freezing process consisting of an initial fast spread of ice throughout the vascular system followed by mesophyll freezing. While mesophyll freezing was homogeneously in Poa alpina, Rhododendron ferrugineum and Senecio incanus as determined by IDTA, DIF showed a distinct pattern only in S. incanus, with the leaf tips being affected earlier. In Cinnamomum camphora, a mottled freezing pattern of small mesophyll compartments was observed by both methods. In IDTA images, a random pattern predominated, while in DIF images, compartments closer to lower order veins were affected earlier. The increase of F(0) following mesophyll freezing started after a species-specific time lag of up to 26 min. The start of the F(0) increase and its slope were significantly enhanced at lower temperatures, which suggest a higher strain on mesophyll protoplasts when freezing occurs at lower temperatures.

  19. 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…

  20. 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…

  1. Risk factors for depressive symptomatology in a drug using population.

    PubMed Central

    Buckner, J C; Mandell, W

    1990-01-01

    This study employs a prospective design to examine possible personality, drug use, stressful life event, and social support-related variables associated with the onset of a depressive episode in a cohort of psychoactive drug using young adults. Two waves of data, collected one year apart, were available on 942 individuals. Cases (n = 62) were free of depressive symptoms at time 1 but reported significant symptomatology at time 2 as measured by the depression subscale of the Brief Symptom Inventory. Controls (n = 490) were those free of depressive symptoms at both time points. In multivariate analyses, users of the central nervous system depressant methaqualone had a nearly four-fold elevated risk for depressed mood as compared to nonusers. Additional risk factors significant after multivariate adjustment included lower self-esteem at time 1 and negative life events. These results highlight the multifactorial nature of depressive symptomatology. PMID:2327536

  2. 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…

  3. 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

  4. Assigning thermodynamic temperatures to high-temperature fixed-points

    NASA Astrophysics Data System (ADS)

    Woolliams, E. R.; Bloembergen, P.; Machin, G.

    2013-09-01

    Workpackage five of the High Temperature Fixed-Point research programme will determine the thermodynamic temperature for the equilibrium melting transition of the pure eutectic systems of Re-C, Pt-C and Co-C and, in addition, the freezing point of Cu. Measurements of four different cells of each type will be made by nine participating laboratories. This paper describes how the melt sensitivity to the rate of the previous freeze, furnace effects and cell impurities will be accounted for and how the results will be combined allowing for all existing correlations.

  5. 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

  6. Seeing fearful body language rapidly freezes the observer's motor cortex.

    PubMed

    Borgomaneri, Sara; Vitale, Francesca; Gazzola, Valeria; Avenanti, Alessio

    2015-04-01

    Fearful body language is a salient signal alerting the observer to the presence of a potential threat in the surrounding environment. Although detecting potential threats may trigger an immediate reduction of motor output in animals (i.e., freezing behavior), it is unclear at what point in time similar reductions occur in the human motor cortex and whether they originate from excitatory or inhibitory processes. Using single-pulse and paired-pulse transcranial magnetic stimulation (TMS), here we tested the hypothesis that the observer's motor cortex implements extremely fast suppression of motor readiness when seeing emotional bodies - and fearful body expressions in particular. Participants observed pictures of body postures and categorized them as happy, fearful or neutral while receiving TMS over the right or left motor cortex at 100-125 msec after picture onset. In three different sessions, we assessed corticospinal excitability, short intracortical inhibition (SICI) and intracortical facilitation (ICF). Independently of the stimulated hemisphere and the time of the stimulation, watching fearful bodies suppressed ICF relative to happy and neutral body expressions. Moreover, happy expressions reduced ICF relative to neutral actions. No changes in corticospinal excitability or SICI were found during the task. These findings show extremely rapid bilateral modulation of the motor cortices when seeing emotional bodies, with stronger suppression of motor readiness when seeing fearful bodies. Our results provide neurophysiological support for the evolutionary notions that emotion perception is inherently linked to action systems and that fear-related cues induce an urgent mobilization of motor reactions.

  7. Freezing transition in decaying Burgers turbulence and random matrix dualities

    NASA Astrophysics Data System (ADS)

    Fyodorov, Y. V.; Le Doussal, P.; Rosso, A.

    2010-06-01

    We reveal a phase transition with decreasing viscosity ν at ν=νc>0 in one-dimensional decaying Burgers turbulence with a power-law-correlated random profile of Gaussian-distributed initial velocities \\overline{v(x,0)v(x',0)}\\sim\\vert x-x'\\vert ^{-2} . The low-viscosity phase exhibits non-Gaussian one-point probability density of velocities, continuously dependent on ν, reflecting a spontaneous one-step replica symmetry breaking (RSB) in the associated statistical-mechanics problem. We obtain the low orders cumulants analytically. Our results, which are checked numerically, are based on combining insights in the mechanism of the freezing transition in random logarithmic potentials with an extension of duality relations discovered recently in the random matrix theory. They are essentially non-mean-field in nature as also demonstrated by the shock size distribution computed numerically and different from the short-range-correlated Kida model. We also provide some insights for the finite-viscosity behaviour of velocities in the latter model.

  8. Mass production of shaped particles through vortex ring freezing.

    PubMed

    An, Duo; Warning, Alex; Yancey, Kenneth G; Chang, Chun-Ti; Kern, Vanessa R; Datta, Ashim K; Steen, Paul H; Luo, Dan; Ma, Minglin

    2016-01-01

    A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be 'frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials. PMID:27488831

  9. Mass production of shaped particles through vortex ring freezing

    PubMed Central

    An, Duo; Warning, Alex; Yancey, Kenneth G.; Chang, Chun-Ti; Kern, Vanessa R.; Datta, Ashim K.; Steen, Paul H.; Luo, Dan; Ma, Minglin

    2016-01-01

    A vortex ring is a torus-shaped fluidic vortex. During its formation, the fluid experiences a rich variety of intriguing geometrical intermediates from spherical to toroidal. Here we show that these constantly changing intermediates can be ‘frozen' at controlled time points into particles with various unusual and unprecedented shapes. These novel vortex ring-derived particles, are mass-produced by employing a simple and inexpensive electrospraying technique, with their sizes well controlled from hundreds of microns to millimetres. Guided further by theoretical analyses and a laminar multiphase fluid flow simulation, we show that this freezing approach is applicable to a broad range of materials from organic polysaccharides to inorganic nanoparticles. We demonstrate the unique advantages of these vortex ring-derived particles in several applications including cell encapsulation, three-dimensional cell culture, and cell-free protein production. Moreover, compartmentalization and ordered-structures composed of these novel particles are all achieved, creating opportunities to engineer more sophisticated hierarchical materials. PMID:27488831

  10. 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

  11. Effect of hyperbaric oxygen on glucose utilization in a freeze-traumatized rat brain

    SciTech Connect

    Contreras, F.L.; Kadekaro, M.; Eisenberg, H.M.

    1988-01-01

    Local cerebral glucose utilization was measured with the autoradiographic 2-deoxyglucose technique in rats injured by a focal parietal cortical freeze lesion then treated with hyperbaric oxygen (HBO). The cold lesion depressed glucose utilization in the contralateral as well as in the ipsilateral hemisphere. The largest decreases were observed in ipsilateral cortical areas. Treatment of lesioned animals with HBO at 2 atm for 90 minutes on each of 4 consecutive days tended to increase the overall cerebral glucose utilization measured 5 days after injury when compared to animals exposed to normobaric air. This improvement reached statistical significance in five of the 21 structures studied: the auditory cortex, medial geniculate body, superior olivary nucleus, and lateral geniculate body ipsilateral to the lesion, and the mammillary body. The data indicate that changes in lesioned rats exposed to HBO are not restricted to the period of time that the animals are in the hyperbaric chamber but are persistent.

  12. Depressive symptoms in institutionalized older adults

    PubMed Central

    Santiago, Lívia Maria; Mattos, Inês Echenique

    2014-01-01

    OBJECTIVE To estimate the prevalence of depressive symptoms among institutionalized elderly individuals and to analyze factors associated with this condition. METHODS This was a cross-sectional study involving 462 individuals aged 60 or older, residents in long stay institutions in four Brazilian municipalities. The dependent variable was assessed using the 15-item Geriatric Depression Scale. Poisson’s regression was used to evaluate associations with co-variables. We investigated which variables were most relevant in terms of presence of depressive symptoms within the studied context through factor analysis. RESULTS Prevalence of depressive symptoms was 48.7%. The variables associated with depressive symptoms were: regular/bad/very bad self-rated health; comorbidities; hospitalizations; and lack of friends in the institution. Five components accounted for 49.2% of total variance of the sample: functioning, social support, sensory deficiency, institutionalization and health conditions. In the factor analysis, functionality and social support were the components which explained a large part of observed variance. CONCLUSIONS A high prevalence of depressive symptoms, with significant variation in distribution, was observed. Such results emphasize the importance of health conditions and functioning for institutionalized older individuals developing depression. They also point to the importance of providing opportunities for interaction among institutionalized individuals. PMID:24897042

  13. Winter depression and diabetes.

    PubMed

    Ernst, Christine R

    2012-12-01

    Depression is a common and often harmful disorder, which is frequently associated with the winter season. Research has shown a link between type 2 diabetes mellitus and depression. Furthermore, diabetics with depression have a higher rate of adverse outcomes. Little has been published regarding the seasonality of depression in diabetics. The case report described in this article concerns a 65-year-old woman with type 2 diabetes and a history of winter depression. Current evidence-based management options are reviewed. PMID:23089656

  14. [Depression and psoriasis].

    PubMed

    Misery, L

    2012-04-01

    Psychiatric co-morbidity is very frequently associated with psoriasis and depression is observed in numerous patients with psoriasis. Early detection and treatment are very important. The links between psoriasis and depression are not only psychopathological. Biological factors could also explain this association. There is a vicious circle psoriasis-alteration of quality of life-depression, but psoriasis improvement is not always followed by an improvement of depression. A contrario, it is obvious that a depressive patient has a bad observance of treatment.

  15. 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

  16. Tipping Point

    MedlinePlus

    ... Tipping Point by CPSC Blogger September 22 appliance child Childproofing CPSC danger death electrical fall furniture head injury product safety television tipover tv Watch the video in Adobe Flash format. Almost weekly, we see ...

  17. Eskimo1 mutants of Arabidopsis are constitutively freezing-tolerant.

    PubMed

    Xin, Z; Browse, J

    1998-06-23

    Temperate plants develop a greater ability to withstand freezing in response to a period of low but nonfreezing temperatures through a complex, adaptive process of cold acclimation. Very little is known about the signaling processes by which plants perceive the low temperature stimulus and transduce it into the nucleus to activate genes needed for increased freezing tolerance. To help understand the signaling processes, we have isolated mutants of Arabidopsis that are constitutively freezing-tolerant in the absence of cold acclimation. Freezing tolerance of wild-type Arabidopsis was increased from -5.5 degreesC to -12.6 degreesC by cold acclimation whereas the freezing tolerance of 26 mutant lines ranged from -6.8 degreesC to -10.6 degreesC in the absence of acclimation. Plants with mutations at the eskimo1 (esk1) locus accumulated high levels of proline, a compatible osmolyte, but did not exhibit constitutively increased expression of several cold-regulated genes involved in freezing tolerance. RNA gel blot analysis suggested that proline accumulation in esk1 plants was mediated by regulation of transcript levels of genes involved in proline synthesis and degradation. The characterization of esk1 mutants and results from other mutants suggest that distinct signaling pathways activate different aspects of cold acclimation and that activation of one pathway can result in considerable freezing tolerance without activation of other pathways.

  18. Metabolic changes in Avena sativa crowns recovering from freezing.

    PubMed

    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.

  19. 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

  20. 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