Structurally Caused Freezing Point Depression of Biological Tissues
Bloch, Rene; Walters, D. H.; Kuhn, Werner
1963-01-01
When investigating the freezing behaviour (by thermal analysis) of the glycerol-extracted adductor muscle of Mytilus edulis it was observed that the temperature of ice formation in the muscular tissue was up to 1.5°C lower than the freezing point of the embedding liquid, a 0.25 N KCl solution with pH = 4.9 with which the tissue had been equilibrated prior to the freezing experiment. A smaller freezing point depression was observed if the pH values of the embedding 0.25 N KCl solution were above or below pH = 4.9. Reasoning from results obtained previously in analogous experiments with artificial gels, the anomalous freezing depression is explained by the impossibility of growing at the normal freezing temperature regular macroscopic crystals inside the gel, due to the presence of the gel network. The freezing temperature is here determined by the size of the microprisms penetrating the meshes of the network at the lowered freezing temperature. This process leads finally to an ice block of more or less regular structure in which the filaments are embedded. Prerequisite for this hindrance of ideal ice growth is a sufficient tensile strength of the filamental network. The existence of structurally caused freezing point depression in biological tissue is likely to invalidate many conclusions reported in the literature, in which hypertonicity was deduced from cryoscopic data. PMID:13971682
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.
THE FREEZING POINT DEPRESSION OF MAMMALIAN TISSUES AFTER SUDDEN HEATING IN BOILING DISTILLED WATER
Appelboom, Johannes W. Th.; Brodsky, William A.; Tuttle, William S.; Diamond, Israel
1958-01-01
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 CO2 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. PMID:13563805
Oxygen demand of aircraft and airfield pavement deicers and alternative freezing point depressants
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.
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…
Brodsky, William A.; Appelboom, Johannes W.; Dennis, Warren H.; Rehm, Warren S.; Miley, John F.; Diamond, Israel
1956-01-01
The freezing point depression of freshly excised frozen tissues, pulverized in a hydraulic press or in a mortar, is greater than that of plasma. Even at 0°C. the freezing point depression of such homogenates increases significantly with time. Dilution data indicate that such freezing point data are valid. The presence of intact cells has been shown in smears of tissues pulverized in a mortar, but not in smears of those crushed in a hydraulic press. The osmolarity of various diluent solutions affects the calculated osmotic activity of tissue homogenates presumably because of delayed diffusion between the diluent and cell fluid. With a hypertonic NaCl diluent, spuriously low values of tissue osmotic activity are found from calculations assuming instantaneous mixing between homogenates and diluents. The limitations of data from cryoscopic experiments and from tissue-swelling experiments are discussed in relation to the basic question of whether or not cell fluid is isotonic to extracellular fluid. PMID:13385447
Plant moisture stress: a portable freezing-point meter compared with the psychrometer
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cary, J.W.; Fisher, H.D.
A small portable instrument for measuring the freezing-point depression of plant tissue has been developed for field use. The instrument is easy to operate and can be constructed from materials costing less than $100. Moisture stress measurements made with the freezing-point meter on a variety of plants were compared with vapor pressure psychrometer measurements. Variation between duplicates in the freezing point averaged 1.2 bars, but differences between stress measurements made with the psychrometer and freezing-point instrument averaged 2.6 bars. 11 references, 5 figures, 2 tables.
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,…
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).
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.
Fuel freeze-point investigations. Final report, September 1982-March 1984
DOE Office of Scientific and Technical Information (OSTI.GOV)
Desmarais, L.A.; Tolle, F.F.
1984-07-01
The objective of this program was to conduct a detailed assessment of the low-temperature environment to which USAF aircraft are exposed for the purpose of defining a maximum acceptable fuel freeze-point and also to define any operational changes required with the use of a high freeze-point fuel. A previous study of B-52, C-141, and KC-135 operational missions indicated that the -58 C freeze point specification was too conservative. Based on recommendations resulting from the previous program, several improvements in the method of analysis were made, such as: expansion of the atmospheric temperature data base, the addition of ground temperature analysis,more » the addition of fuel-freezing analysis to the one-dimensional fuel-temperature computer program, and the examination of heat transfer in external fuel tanks, such as pylon or tip tanks. The B-52, C-141, and KC-135 mission were analyzed again, along with the operational missions of two tactical airplanes, the A-10 and F-15; -50C was determined to be the maximum allowable freeze point for a general-purpose USAF aviation turbine fuel. Higher freeze points can be tolerated if the probability of operational interference is acceptably low or if operational changes can be made. Study of atmospheric temperatures encountered for the missions of the five-study aircraft indicates that a maximum freeze point of -48 C would not likely create any operational difficulties in Northern Europe.« less
NASA Astrophysics Data System (ADS)
Labenski, J. R.; Tew, W. L.; Benz, S. P.; Nam, S. W.; Dresselhaus, P.
2008-02-01
A Johnson-noise thermometer (JNT) has been used with a quantized voltage noise source (QVNS), as a calculable reference to determine the ratio of temperatures near the Zn freezing point to those near the Sn freezing point. The temperatures are derived in a series of separate measurements comparing the synthesized noise power from the QVNS with that of Johnson noise from a known resistance. The synthesized noise power is digitally programed to match the thermal noise powers at both temperatures and provides the principle means of scaling the temperatures. This produces a relatively flat spectrum for the ratio of spectral noise densities, which is close to unity in the low-frequency limit. The data are analyzed as relative spectral ratios over the 4.8 to 450 kHz range averaged over a 3.2 kHz bandwidth. A three-parameter model is used to account for differences in time constants that are inherently temperature dependent. A drift effect of approximately -6 μK·K-1 per day is observed in the results, and an empirical correction is applied to yield a relative difference in temperature ratios of -11.5 ± 43 μK·K-1 with respect to the ratio of temperatures assigned on the International Temperature Scale of 1990 (ITS-90). When these noise thermometry results are combined with results from acoustic gas thermometry at temperatures near the Sn freezing point, a value of T - T 90 = 7 ± 30 mK for the Zn freezing point is derived.
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.
Freezing induces a loss of freeze tolerance in an overwintering insect.
Brown, C L; Bale, J S; Walters, K F A
2004-07-22
Cold-hardy insects overwinter by one of two main strategies: freeze tolerance and freeze avoidance by supercooling. As a general model, many freeze-tolerant species overwinter in extreme climates, freeze above -10 degrees C via induction by ice-nucleating agents, and once frozen, can survive at temperatures of up to 40 degrees C or more below the initial freezing temperature or supercooling point (SCP). It has been assumed that the SCP of freeze-tolerant insects is unaffected by the freezing process and that the freeze-tolerant state is therefore retained in winter though successive freeze-thaw cycles of the body tissues and fluids. Studies on the freeze-tolerant larva of the hoverfly Syrphus ribesii reveal this assumption to be untrue. When a sample with a mean 'first freeze' SCP of -7.6 degrees C (range of -5 degrees C to -9.5 degrees C) were cooled, either to -10 degrees C or to their individual SCP, on five occasions, the mean SCP was significantly depressed, with some larvae subsequently freezing as low as -28 degrees C. Only larvae that froze at the same consistently high temperature above -10 degrees C were alive after being frozen five times. The wider occurrence of this phenomenon would require a fundamental reassessment of the dynamics and distinctions of the freeze-tolerant and freeze-avoiding strategies of insect overwintering. Copyright 2004 The Royal Society
Guerrero, Samantha; Pastor, Josep; Tvarijonaviciute, Asta; Cerón, José Joaquín; Balestra, Graziano; Caldin, Marco
2017-11-01
Urine osmolality (UOsm) is considered the most accurate measure of urine concentration and is used to assess body fluid homeostasis and renal function. We performed analytical validation of freezing point depression measurement of canine UOsm, to establish reference intervals (RIs) and to determine the effect of age, sex, and reproductive status on UOsm in dogs. Clinically healthy dogs ( n = 1,991) were retrospectively selected and stratified in groups by age (young [0-12 mo], adults [13-84 mo], and seniors [>84 mo]), sex (females and males), and reproductive status (intact and neutered). RIs were calculated for each age group. Intra- and inter-assay coefficients of variation were <1% in all cases. Good linearity ( r 2 = 1, p < 0.001) and recovery (89-98%) were observed. The limit of detection and limit of quantification were zero. Urine specific gravity and UOsm had a highly significant positive correlation ( r = 0.96, p < 0.001) but had inconsistent agreement. The 95% RI for canine UOsm was 369-2,416 mOsm/kg in young and adult dogs, and 366-2,178 mOsm/kg in seniors. Senior dogs had a significantly lower UOsm than young and adult dogs ( p < 0.000). Neutered females had a significantly lower UOsm than intact female dogs ( p < 0.002). These results indicate that the method evaluated is adequate for UOsm measurement and that RIs based on age and reproductive status should be used in dogs.
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.
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
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.
Origin of melting point depression for rare gas solids confined in carbon pores
DOE Office of Scientific and Technical Information (OSTI.GOV)
Morishige, Kunimitsu, E-mail: morishi@chem.ous.ac.jp; Kataoka, Takaaki
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 thatmore » 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.« less
NASA Astrophysics Data System (ADS)
Zvizdic, Davor; Veliki, Tomislav; Grgec Bermanec, Lovorka
2008-06-01
This article describes the realization of the International Temperature Scale in the range from 234.3 K (mercury triple point) to 1084.62°C (copper freezing point) at the Laboratory for Process Measurement (LPM), Faculty of Mechanical Engineering and Naval Architecture (FSB), University of Zagreb. The system for the realization of the ITS-90 consists of the sealed fixed-point cells (mercury triple point, water triple point and gallium melting point) and the apparatus designed for the optimal realization of open fixed-point cells which include the gallium melting point, tin freezing point, zinc freezing point, aluminum freezing point, and copper freezing point. The maintenance of the open fixed-point cells is described, including the system for filling the cells with pure argon and for maintaining the pressure during the realization.
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.
Production of Low-Freezing-Point Highly Branched Alkanes through Michael Addition.
Jing, Yaxuan; Xia, Qineng; Liu, Xiaohui; Wang, Yanqin
2017-12-22
A new approach for the production of low-freezing-point, high-quality fuels from lignocellulose-derived molecules was developed with Michael addition as the key step. Among the investigated catalysts, CoCl 2 ⋅6 H 2 O was found most active for the Michael addition of 2,4-pentanedione with FA (single aldol adduct of furfural and acetone, 4-(2-furanyl)-3-butene-2-one). Over CoCl 2 ⋅6 H 2 O, a high carbon yield of C 13 oxygenates (about 75 %) can be achieved under mild conditions (353 K, 20 h). After hydrodeoxygenation, low-freezing-point (<223 K) branched alkanes with 13 carbons within jet fuel ranges were obtained over a Pd/NbOPO 4 catalyst. Furthermore, C 18,23 fuel precursors could be easily synthesized through Michael addition of 2,4-pentanedione with DFA (double-condensation product of furfural and acetone) under mild conditions and the molar ratio of C 18 /C 23 is dependent on the reaction conditions of Michael addition. After hydrodeoxygenation, high density (0.8415 g mL -1 ) and low-freezing-point (<223 K) branched alkanes with 18, 23 carbons within lubricant range were also obtained over a Pd/NbOPO 4 catalyst. These highly branched alkanes can be directly used as transportation fuels or additives. This work opens a new strategy for the synthesis of highly branched alkanes with low freezing point from renewable biomass. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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.
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.
1986-07-01
pure water. Dissolved ions in the soil solution lower the freezing point; this is called freezing point depression. Many of the early studies of...them in the remaining soil solution . The temperature and concentration of this solution affect the chemical reactions and the forms of ions in...in the soil solution freezes, more concentrated "% solutes will be present in soil solution . 3. Water will travel even in frozen soils and sediments
DOE Office of Scientific and Technical Information (OSTI.GOV)
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 thismore » 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.« less
Critical viewpoints on the methods of realizing the metal freezing points of the ITS-90
NASA Astrophysics Data System (ADS)
Ma, C. K.
1995-08-01
The time-honored method for realizing the freezing point tf of a metal (in practice necessarily a dilute alloy) is that of continuous, slow freezing where the plateau temperature (which is the result of solidifying material's being so pure that its phase-transition temperature is observably constant) is measured. The freezing point being an equilibrium temperature, Ancsin considers this method to be inappropriate in principle: equilibrium between the solid and liquid phases cannot be achieved while the solid is being cooled to dispose of the releasing latent heat and while it is accreting at the expense of the liquid. In place of the continuous freezing method he has employed the pulse-heating method (in which the sample is allowed to approach equilibrium after each heat pulse) in his study of Ag; his measurements suggest that freezing can produce non-negligible errors. Here we examine both methods and conclude that the freezing method, employing an inside solid-liquid interface thermally isolated by an outside interface, can provide realizations of the highest accuracy; in either method, perturbation, by inducing solid-liquid phase transition continuously or intermittently, is essential for detecting equilibrium thermally. The respective merits and disadvantages of these two methods and also of the inner-melt method are discussed. We conclude that in a freezing-point measurement what is being measured is in effect the however minutely varying phase transition, and nonconstitutional equilibrium, temperature ti at the solid-liquid interface. The objective is then to measure the ti that is the best measure of tf, which is, normally, the plateau temperature.
The initial freezing point temperature of beef rises with the rise in pH: a short communication.
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. Copyright © 2013 Elsevier Ltd. All rights reserved.
Novel method of realizing metal freezing points by induced solidification
NASA Astrophysics Data System (ADS)
Ma, C. K.
1997-07-01
The freezing point of a pure metal, tf, is the temperature at which the solid and liquid phases are in equilibrium. The purest metal available is actually a dilute alloy. Normally, the liquidus point of a sample, tl, at which the amount of the solid phase in equilibrium with the liquid phase is minute, provides the closest approximation to tf. Thus the experimental realization of tf is a matter of realizing tl. The common method is to cool a molten sample continuously so that it supercools and recalesces. The highest temperature after recalescence is normally the best experimental value of tl. In the realization, supercooling of the sample at the sample container and the thermometer well is desirable for the formation of dual solid-liquid interfaces to thermally isolate the sample and the thermometer. However, the subsequent recalescence of the supercooled sample requires the formation of a certain amount of solid, which is not minute. Obviously, the plateau temperature is not the liquidus point. In this article we describe a method that minimizes supercooling. The condition that provides tl is closely approached so that the latter may be measured. As the temperature of the molten sample approaches the anticipated value of tl, a small solid of the same alloy is introduced into the sample to induce solidification. In general, solidification does not occur as long as the temperature is above or at tl, and occurs as soon as the sample supercools minutely. Thus tl can be obtained, in principle, by observing the temperature at which induced solidification begins. In case the solid is introduced after the sample has supercooled slightly, a slight recalescence results and the subsequent maximum temperature is a close approximation to tl. We demonstrate that the principle of induced solidification is indeed applicable to freezing point measurements by applying it to the design of a copper-freezing-point cell for industrial applications, in which a supercooled sample is
Determination of end point of primary drying in freeze-drying process control.
Patel, Sajal M; Doen, Takayuki; Pikal, Michael J
2010-03-01
Freeze-drying is a relatively expensive process requiring long processing time, and hence one of the key objectives during freeze-drying process development is to minimize the primary drying time, which is the longest of the three steps in freeze-drying. However, increasing the shelf temperature into secondary drying before all of the ice is removed from the product will likely cause collapse or eutectic melt. Thus, from product quality as well as process economics standpoint, it is very critical to detect the end of primary drying. Experiments were conducted with 5% mannitol and 5% sucrose as model systems. The apparent end point of primary drying was determined by comparative pressure measurement (i.e., Pirani vs. MKS Baratron), dew point, Lyotrack (gas plasma spectroscopy), water concentration from tunable diode laser absorption spectroscopy, condenser pressure, pressure rise test (manometric temperature measurement or variations of this method), and product thermocouples. Vials were pulled out from the drying chamber using a sample thief during late primary and early secondary drying to determine percent residual moisture either gravimetrically or by Karl Fischer, and the cake structure was determined visually for melt-back, collapse, and retention of cake structure at the apparent end point of primary drying (i.e., onset, midpoint, and offset). By far, the Pirani is the best choice of the methods tested for evaluation of the end point of primary drying. Also, it is a batch technique, which is cheap, steam sterilizable, and easy to install without requiring any modification to the existing dryer.
Zelent, Bogumil; Bryan, Michael A; Sharp, Kim A; Vanderkooi, Jane M
2009-05-01
The influence of proteins and solutes on hysteresis of freezing and melting of water was measured by infrared (IR) spectroscopy. Of the solutes examined, poly-L-arginine and flounder antifreeze protein produced the largest freezing point depression of water, with little effect on the melting temperature. Poly-L-lysine, poly-L-glutamate, cytochrome c and bovine serum albumin had less effect on the freezing of water. Small compounds used to mimic non-polar (trimethylamine N-oxide, methanol), positively charged (guanidinium chloride, NH(4)Cl, urea) and negatively charged (Na acetate) groups on protein surfaces were also examined. These molecules and ions depress water's freezing point and the melting profiles became broad. Since infrared absorption measures both bulk solvent and solvent bound to the solutes, this result is consistent with solutes interacting with liquid water. The amide I absorption bands of antifreeze protein and poly-L-arginine do not detectably change with the phase transition of water. An interpretation is that the antifreeze protein and poly-L-arginine order liquid water such that the water around the group is ice-like.
Effect of Impurities on the Freezing Point of Zinc
NASA Astrophysics Data System (ADS)
Sun, Jianping; Rudtsch, Steffen; Niu, Yalu; Zhang, Lin; Wang, Wei; Den, Xiaolong
2017-03-01
The knowledge of the liquidus slope of impurities in fixed-point metal defined by the International Temperature Scale of 1990 is important for the estimation of uncertainties and correction of fixed point with the sum of individual estimates method. Great attentions are paid to the effect of ultra-trace impurities on the freezing point of zinc in the National Institute of Metrology. In the present work, the liquidus slopes of Ga-Zn, Ge-Zn were measured with the slim fixed-point cell developed through the doping experiments, and the temperature characteristics of the phase diagram of Fe-Zn were furthermore investigated. A quasi-adiabatic Zn fixed-point cell was developed with the thermometer well surrounded by the crucible with the pure metal, and the temperature uniformity of less than 20 mK in the region where the metal is located was obtained. The previous doping experiment of Pb-Zn with slim fixed-point cell was checked with quasi-adiabatic Zn fixed-point cell, and the result supports the previous liquidus slope measured with the traditional fixed-point realization.
ERIC Educational Resources Information Center
Li, Shirong; Guo, Jianzhong; Wang, Kewang; Chen, Lin; Hu, Daodao; Bai, Yunshan
2017-01-01
An improved apparatus for measuring freezing points has been developed. Compared to the traditional Beckmann freezing point instrument, the improved one overcame prior difficulties with solidification of liquid and made the solid-liquid equilibrium reversible with heat compensation from a heating tube. The reliability and accuracy were carefully…
Note: equation of state and the freezing point in the hard-sphere model.
Robles, Miguel; López de Haro, Mariano; Santos, Andrés
2014-04-07
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.
NASA Astrophysics Data System (ADS)
Qin, N.; Wu, Y.; Wang, H. W.; Wang, Y. Y.
2017-12-01
In this paper, based on the background of snowmelt de-icing tools, we studied the effect of salt on freezing point and melting rate of ice through laboratory test and FLUENT numerical simulation analysis. It was confirmed that the freezing point is inversely proportional to the salt solid content, and with the salt solid content increasing, the freezing process of salt water gradually accepts the curing rule of non-crystal solids. At the same temperature, an increase in the salt solid content, the ice melting rate increase by the empirical formula linking the melting time with temperature and salt content. The theoretical aspects of solid/fluid transformation are discussed in detail.
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.
Freezing temperature of finger skin.
Wilson, O; Goldman, R F; Molnar, G W
1976-10-01
In 45 subjects, 154 frostnips of the finger were induced by cooling in air at -15 degrees C with various wind speeds. The mean supercooled skin temperature at which frostnip appeared was -9.4 degrees C. The mean skin temperature rise due to heat of fusion at ice crystallization was 5.3 degrees C. The skin temperature rose to what was termed the apparent freezing point. The relation of this point to the supercooled skin temperature was analyzed for the three wind speeds used. An apparent freezing point for a condition of no supercooling was calculated, estimating the highest temperature at which skin freezes at a given wind speed. The validity of the obtained differences in apparent freezing point was tested by an analysis of covariance. Although not statistically significant, the data suggest that the apparent freezing point with no supercooling decreases with increasing wind velocity. The highest calculated apparent freezing point at -15 degrees C and 6.8 m/s was 1.2 degrees C lower than the true freezing point for skin previously determined in brine, which is a statistically significant difference.
Close-packed floating clusters: granular hydrodynamics beyond the freezing point?
Meerson, Baruch; Pöschel, Thorsten; Bromberg, Yaron
2003-07-11
Monodisperse granular flows often develop regions with hexagonal close packing of particles. We investigate this effect in a system of inelastic hard spheres driven from below by a "thermal" plate. Molecular dynamics simulations show, in a wide range of parameters, a close-packed cluster supported by a low-density region. Surprisingly, the steady-state density profile, including the close-packed cluster part, is well described by a variant of Navier-Stokes granular hydrodynamics (NSGH). We suggest a simple explanation for the success of NSGH beyond the freezing point.
A theoretical extension of the soil freezing curve paradigm
NASA Astrophysics Data System (ADS)
Amiri, Erfan A.; Craig, James R.; Kurylyk, Barret L.
2018-01-01
Numerical models of permafrost evolution in porous media typically rely upon a smooth continuous relation between pore ice saturation and sub-freezing temperature, rather than the abrupt phase change that occurs in pure media. Soil scientists have known for decades that this function, known as the soil freezing curve (SFC), is related to the soil water characteristic curve (SWCC) for unfrozen soils due to the analogous capillary and sorptive effects experienced during both soil freezing and drying. Herein we demonstrate that other factors beyond the SFC-SWCC relationship can influence the potential range over which pore water phase change occurs. In particular, we provide a theoretical extension for the functional form of the SFC based upon the presence of spatial heterogeneity in both soil thermal conductivity and the freezing point depression of water. We infer the functional form of the SFC from many abrupt-interface 1-D numerical simulations of heterogeneous systems with prescribed statistical distributions of water and soil properties. The proposed SFC paradigm extension has the appealing features that it (1) is determinable from measurable soil and water properties, (2) collapses into an abrupt phase transition for homogeneous media, (3) describes a wide range of heterogeneity within a single functional expression, and (4) replicates the observed hysteretic behavior of freeze-thaw cycles in soils.
Freezing points and small-scale deicing tests for salts of levulinic acid made from grain sorghum.
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.
NASA Astrophysics Data System (ADS)
Li, Zhibin; Chen, Yidian; Li, Danning; Huang, Mei
2018-01-01
We investigate the baryon number susceptibilities up to fourth order along different freeze-out lines in a holographic QCD model with a critical end point (CEP), and we propose that the peaked baryon number susceptibilities along the freeze-out line can be used as a clean signature to locate the CEP in the QCD phase diagram. On the temperature and baryon chemical potential plane, the cumulant ratio of the baryon number susceptibilities (up to fourth order) forms a ridge along the phase boundary, and develops a sword-shaped “mountain” standing upright around the CEP in a narrow and oblate region. The measurement of baryon number susceptibilities from heavy-ion collision experiments is along the freeze-out line. If the freeze-out line crosses the foot of the CEP mountain, then one can observe the peaked baryon number susceptibilities along the freeze-out line, and the kurtosis of the baryon number distributions has the highest magnitude. The data from the first phase of the beam energy scan program at the Relativistic Heavy Ion Collider indicates that there should be a peak of the kurtosis of the baryon number distribution at a collision energy of around 5 GeV, which suggests that the freeze-out line crosses the foot of the CEP mountain and the summit of the CEP should be located nearby, around a collision energy of 3-7 GeV. Supported by NSFC (11275213, and 11261130311) (CRC 110 by DFG and NSFC), CAS key project KJCX2-EW-N01, and Youth Innovation Promotion Association of CAS
Freeze-drying process design by manometric temperature measurement: design of a smart freeze-dryer.
Tang, Xiaolin Charlie; Nail, Steven L; Pikal, Michael J
2005-04-01
To develop a procedure based on manometric temperature measurement (MTM) and an expert system for good practices in freeze drying that will allow development of an optimized freeze-drying process during a single laboratory freeze-drying experiment. Freeze drying was performed with a FTS Dura-Stop/Dura-Top freeze dryer with the manometric temperature measurement software installed. Five percent solutions of glycine, sucrose, or mannitol with 2 ml to 4 ml fill in 5 ml vials were used, with all vials loaded on one shelf. Details of freezing, optimization of chamber pressure, target product temperature, and some aspects of secondary drying are determined by the expert system algorithms. MTM measurements were used to select the optimum shelf temperature, to determine drying end points, and to evaluate residual moisture content in real-time. MTM measurements were made at 1 hour or half-hour intervals during primary drying and secondary drying, with a data collection frequency of 4 points per second. The improved MTM equations were fit to pressure-time data generated by the MTM procedure using Microcal Origin software to obtain product temperature and dry layer resistance. Using heat and mass transfer theory, the MTM results were used to evaluate mass and heat transfer rates and to estimate the shelf temperature required to maintain the target product temperature. MTM product dry layer resistance is accurate until about two-thirds of total primary drying time is over, and the MTM product temperature is normally accurate almost to the end of primary drying provided that effective thermal shielding is used in the freeze-drying process. The primary drying times can be accurately estimated from mass transfer rates calculated very early in the run, and we find the target product temperature can be achieved and maintained with only a few adjustments of shelf temperature. The freeze-dryer overload conditions can be estimated by calculation of heat/mass flow at the target product
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.
Fish antifreeze protein and the freezing and recrystallization of ice.
Knight, C A; DeVries, A L; Oolman, L D
Antifreeze glycopeptide and peptides from the blood of polar fishes prevent the growth of ice crystals in water at temperatures down to approximately 1 degree C below freezing point, but do not appreciably influence the equilibrium freezing point. This freezing point hysteresis must be a disequilibrium effect, or it would violate Gibbs' phase rule, but the separate freezing and melting points are experimentally very definite: ice neither melts nor freezes perceptibly within the 'hysteresis gap', for periods of hours or days. We report here unusual crystal faces on ice crystals grown from solutions of very low concentrations of the anti-freeze glycopeptides and peptides. This is a clue to the mechanism of freezing inhibition, and it may be the basis of a simple, very sensitive test for antifreeze material. Very low concentrations of the antifreeze protein are also remarkably effective in preventing the recrystallization of ice.
Validity of a portable urine refractometer: the effects of sample freezing.
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.
Freeze-dried plasma at the point of injury: from concept to doctrine.
Glassberg, Elon; Nadler, Roy; Gendler, Sami; Abramovich, Amir; Spinella, Philip C; Gerhardt, Robert T; Holcomb, John B; Kreiss, Yitshak
2013-12-01
While early plasma transfusion for the treatment of patients with ongoing major hemorrhage is widely accepted as part of the standard of care in the hospital setting, logistic constraints have limited its use in the out-of-hospital setting. Freeze-dried plasma (FDP), which can be stored at ambient temperatures, enables early treatment in the out-of-hospital setting. Point-of-injury plasma transfusion entails several significant advantages over currently used resuscitation fluids, including the avoidance of dilutional coagulopathy, by minimizing the need for crystalloid infusion, beneficial effects on endothelial function, physiological pH level, and better maintenance of intravascular volume compared with crystalloid-based solutions. The Israel Defense Forces Medical Corps policy is that plasma is the resuscitation fluid of choice for selected, severely wounded patients and has thus included FDP as part of its armamentarium for use at the point of injury by advanced life savers, across the entire military. We describe the clinical rationale behind the use of FDP at the point-of-injury, the drafting of the administration protocol now being used by Israel Defense Forces advanced life support providers, the process of procurement and distribution, and preliminary data describing the first casualties treated with FDP at the point of injury. It is our hope that others will be able to learn from our experience, thus improving trauma casualty care around the world.
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.
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.
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;
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.
Molecular biology of freezing tolerance.
Storey, Kenneth B; Storey, Janet M
2013-07-01
Winter survival for many kinds of animals involves freeze tolerance, the ability to endure the conversion of about 65% of total body water into extracellular ice and the consequences that freezing imposes including interruption of vital processes (e.g., heartbeat and breathing), cell shrinkage, elevated osmolality, anoxia/ischemia, and potential physical damage from ice. Freeze-tolerant animals include various terrestrially hibernating amphibians and reptiles, many species of insects, and numerous other invertebrates inhabiting both terrestrial and intertidal environments. Well-known strategies of freezing survival include accumulation of low molecular mass carbohydrate cryoprotectants (e.g., glycerol), use of ice nucleating agents/proteins for controlled triggering of ice growth and of antifreeze proteins that inhibit ice recrystallization, and good tolerance of anoxia and dehydration. The present article focuses on more recent advances in our knowledge of the genes and proteins that support freeze tolerance and the metabolic regulatory mechanisms involved. Important roles have been identified for aquaporins and transmembrane channels that move cryoprotectants, heat shock proteins and other chaperones, antioxidant defenses, and metabolic rate depression. Genome and proteome screening has revealed many new potential targets that respond to freezing, in particular implicating cytoskeleton remodeling as a necessary facet of low temperature and/or cell volume adaptation. Key regulatory mechanisms include reversible phosphorylation control of metabolic enzymes and microRNA control of gene transcript expression. These help to remodel metabolism to preserve core functions while suppressing energy expensive metabolic activities such as the cell cycle. All of these advances are providing a much more complete picture of life in the frozen state. © 2013 American Physiological Society.
Liu, Jing; Zhou, Yi-Xin
2003-09-01
This paper is aimed at investigating the roles of freezing dynamics of a liquid droplet to characterize the properties of the material. In particular, freezing curve-based monitoring was proposed to quickly evaluate the viability of biological materials subject to freezing, re-warming, or other kinds of injury, which is an extremely important issue in practices such as cryobiology, hyperthermia, or freshness evaluation of bio-samples. An integrated micro analysis device was fabricated which is simple in structure and cheap to make. Preliminary freezing results demonstrated that minor changes in a biological material due to freezing or warming injury might result in a significant deviation of its freezing curve from that of the intact biomaterials. Several potential thermal indexes to quantify the material features were pointed out. Further, experiments were performed on some freezing and thawing processes of small amount of water on a cooling surface to test the effects of droplet sizes, measurement sites, cooling strength, and cooling geometry, etc., on the freezing responses of a water droplet. Their implementation in developing a new micro analysis system were suggested. This freezing curve-based monitoring method may open a new strategy for the evaluation of biomaterials subject to destruction in diverse fields.
Effects of freezing conditions on quality changes in blueberries.
Cao, Xuehui; Zhang, Fangfang; Zhao, Dongyu; Zhu, Danshi; Li, Jianrong
2018-03-12
Freezing preservation is one of the most effective methods used to maintain the flavour and nutritional value of fruit. This research studied the effects of different freezing conditions, -20 °C, -40 °C, -80 °C, and immersion in liquid nitrogen, on quality changes of freeze-thawed blueberries. The water distribution estimates of blueberries were measured based on low-field nuclear magnetic resonance (LF-NMR) analysis. The pectin content, drip loss, and fruit texture were also detected to evaluate quality changes in samples. The freezing curves of blueberry showed super-cooling points at -20 °C and - 40 °C, whereas super-cooling points were not observed at -80 °C or in liquid nitrogen. After freeze-thaw treatment, the relaxation time of the cell wall water (T 21 ), cytoplasm water and extracellular space (T 22 ), and vacuole water (T 23 ) were significantly shortened compared to fresh samples, which suggested a lower liquidity. Although the freezing speed for samples immersed in liquid nitrogen was faster than other treatments, samples treated at -80 °C showed better quality regarding vacuole water holding, drip loss, and original pectin content retention. This study contributed to understanding how freezing temperature affects the qualities of blueberries. The super-fast freezing rate might injure fruit, and an appropriate freezing rate could better preserve blueberries. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.
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.
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…
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.
Two-dimensional freezing criteria for crystallizing colloidal monolayers
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang Ziren; Han Yilong; Alsayed, Ahmed M.
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 themore » 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.« less
Adsorption inhibition as a mechanism of freezing resistance in polar fishes.
Raymond, J A; DeVries, A L
1977-01-01
Polar fishes are known to have serum proteins and glycoproteins that protect them from freezing, by a noncolligative process. Measurements of antifreeze concentrations in ice and scanning electron micrographs of freeze-dried antifreeze solutions indicate that the antifreezes are incorporated in ice during freezing. The antifreezes also have a pronounced effect on the crystal habit of ice grown in their presence. Each of four antifreezes investigated caused ice to grow in long needles whose axes were parallel to the ice c axis. Together these results indicate the antifreezes adsorb to ice surfaces and inhibit their growth. A model in which adsorbed antifreezes raise the curvature of growth steps on the ice surface is proposed to account for the observed depression of the temperature at which freezing occurs and agrees well with experimental observations. The model is similar to one previously proposed for other cases of crystal growth inhibition. Images PMID:267952
2013-01-01
Point-of-injury use of reconstituted freeze dried plasma as a resuscitative fluid: A special report for prehospital trauma care Elon Glassberg, MD...in- jury as part of the multidisciplinary efforts to improve trauma victims’ outcome. BACKGROUND Trauma is the leading cause of death among adults be...diabetes.1 Managing the burden of injuries from decades of wars has underscored the importance of trauma research aimed at reducing morbidity and
Inactivation of Kudoa septempunctata in olive flounder meat by liquid freezing.
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.
Are the QRS duration and ST depression cut-points from the Seattle criteria too conservative?
Dunn, Tim; Abdelfattah, Ramy; Aggarwal, Sonya; Pickham, David; Hadley, David; Froelicher, Victor
2015-01-01
Screening athletes with ECGs is aimed at identifying "at-risk" individuals who may have a cardiac condition predisposing them to sudden cardiac death. The Seattle criteria highlight QRS duration greater than 140 ms and ST segment depression in two or more leads greater than 50 μV as two abnormal ECG patterns associated with sudden cardiac death. High school, college, and professional athletes underwent 12 lead ECGs as part of routine pre-participation physicals. Prevalence of prolonged QRS duration was measured using cut-points of 120, 125, 130, and 140 ms. ST segment depression was measured in all leads except leads III, aVR, and V1 with cut-points of 25 μV and 50 μV. Between June 2010 and November 2013, 1595 participants including 297 (167 male, mean age 16.2) high school athletes, 1016 (541 male, mean age 18.8) college athletes, and 282 (mean age 26.6) male professional athletes underwent screening with an ECG. Only 3 athletes (0.2%) had a QRS duration greater than 125 ms. ST segment depression in two or more leads greater than 50 μV was uncommon (0.8%), while the prevalence of ST segment depression in two or more leads increased to 4.5% with a cut-point of 25 μV. Changing the QRS duration cut-point to 125 ms would increase the sensitivity of the screening ECG, without a significant increase in false-positives. However, changing the ST segment depression cut-point to 25 μV would lead to a significant increase in false-positives and would therefore not be justified. Copyright © 2015 Elsevier Inc. All rights reserved.
Hatchling turtles survive freezing during winter hibernation.
Storey, K B; Storey, J M; Brooks, S P; Churchill, T A; Brooks, R J
1988-01-01
Hatchlings of the painted turtle (Chrysemys picta marginata) are unique as the only reptile and highest vertebrate life form known to tolerate the natural freezing of extracellular body fluids during winter hibernation. Turtles survived frequent exposures to temperatures as low as -6 degrees C to -8 degrees C in their shallow terrestrial nests over the 1987-1988 winter. Hatchlings collected in April 1988 had a mean supercooling point of -3.28 +/- 0.24 degrees C and survived 24 hr of freezing at -4 degrees C with 53.4% +/- 1.98% of total body water as ice. Recovery appeared complete after 20 hr of thawing at 3 degrees C. However, freezing at -10.9 degrees C, resulting in 67% ice, was lethal. A survey of possible cryoprotectants revealed a 2- to 3-fold increase in glucose content of liver and blood and a 3-fold increase in blood glycerol in response to freezing. Although quantitatively low, these responses by spring turtles strongly indicate that these may be the winter-active cryoprotectants. The total amino acid pool of blood also increased 2.25-fold in freezing-exposed turtles, and taurine accounted for 52% of the increase. Most organs accumulated high concentrations of lactate during freezing, a response to the ischemic state imposed by extracellular freezing. Changes in glycogen phosphorylase activity and levels of glucose 6-phosphate and fructose 2,6-bisphosphate were also consistent with a dependence on anaerobic glycolysis during freezing. Studies of the molecular mechanisms of natural freeze tolerance in these turtles may identify protective strategies that can be used in mammalian organ cryopreservation technology. PMID:3186730
Theory of freezing in simple systems
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cerjan, C.; Bagchi, B.
The transition parameters for the freezing of two one-component liquids into crystalline solids are evaluated by two theoretical approaches. The first system considered is liquid sodium which crystallizes into a body-centered-cubic (bcc) lattice; the second system is the freezing of adhesive hard spheres into a face-centered-cubic (fcc) lattice. Two related theoretical techniques are used in this evaluation: One is based upon a recently developed bifurcation analysis; the other is based upon the theory of freezing developed by Ramakrishnan and Yussouff. For liquid sodium, where experimental information is available, the predictions of the two theories agree well with experiment and eachmore » other. The adhesive-hard-sphere system, which displays a triple point and can be used to fit some liquids accurately, shows a temperature dependence of the freezing parameters which is similar to Lennard-Jones systems. At very low temperature, the fractional density change on freezing shows a dramatic increase as a function of temperature indicating the importance of all the contributions due to the triplet direction correlation function. Also, we consider the freezing of a one-component liquid into a simple-cubic (sc) lattice by bifurcation analysis and show that this transition is highly unfavorable, independent of interatomic potential choice. The bifurcation diagrams for the three lattices considered are compared and found to be strikingly different. Finally, a new stability analysis of the bifurcation diagrams is presented.« less
Fundamentals of freeze-drying.
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
Key composition optimization of meat processed protein source by vacuum freeze-drying technology.
Ma, Yan; Wu, Xingzhuang; Zhang, Qi; Giovanni, Vigna; Meng, Xianjun
2018-05-01
Vacuum freeze-drying technology is a high technology content, a wide range of knowledge of technology in the field of drying technology is involved, it is also a method of the most complex drying equipment, the largest energy consumption, the highest cost of drying method, but due to the particularity of its dry goods: the freeze-drying food has the advantages of complex water performance is good, cooler and luster of freezing and drying food to maintain good products, less nutrient loss, light weight, easy to carry transportation, easy to long-term preservation, and on the quality is far superior to the obvious advantages of other dried food, making it become the forefront of drying technology research and development. The freeze-drying process of Chinese style ham and western Germany fruit tree tenderloin is studied in this paper, their eutectic point, melting point and collapse temperature, freeze-drying curve and its heat and mass transfer characteristics are got, then the precool temperature and the highest limiting temperature of sublimation interface are determined. The effect of system pressure on freeze-dried rate in freeze-drying process is discussed, and the method of regulating pressure circularly is determined.
NASA Astrophysics Data System (ADS)
Hu, Rui; Liu, Quan
2017-04-01
During the engineering projects with artificial ground freezing (AFG) techniques in coastal area, the freezing effect is affected by groundwater salinity. Based on the theories of artificially frozen soil and heat transfer in porous material, and with the assumption that only the variations of total dissolved solids (TDS) impact on freezing point and thermal conductivity, a numerical model of an AFG project in a saline aquifer was established and validated by comparing the simulated temperature field with the calculated temperature based on the analytic solution of rupak (reference) for single-pipe freezing temperature field T. The formation and development of freezing wall were simulated with various TDS. The results showed that the variety of TDS caused the larger temperature difference near the frozen front. With increasing TDS in the saline aquifer (1 35g/L), the average thickness of freezing wall decreased linearly and the total formation time of the freezing wall increased linearly. Compared with of the scenario of fresh-water (<1g/L), the average thickness of frozen wall decreased by 6% and the total formation time of the freezing wall increased by 8% with each increasing TDS of 7g/L. Key words: total dissolved solids, freezing point, thermal conductivity, freezing wall, numerical simulation Reference D.J.Pringel, H.Eicken, H.J.Trodahl, etc. Thermal conductivity of landfast Antarctic and Arctic sea ice[J]. Journal of Geophysical Research, 2007, 112: 1-13. Lukas U.Arenson, Dave C.Sego. The effect of salinity on the freezing of coarse- grained sand[J]. Canadian Geotechnical Journal, 2006, 43: 325-337. Hui Bing, Wei Ma. Laboratory investigation of the freezing point of saline soil[J]. Cold Regions Science and Technology, 2011, 67: 79-88.
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
Novel Real-Time Diagnosis of the Freezing Process Using an Ultrasonic Transducer
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
Prediction of frozen food properties during freezing using product composition.
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.
NASA Astrophysics Data System (ADS)
da Silva, Rodrigo; Pearce, Jonathan V.; Machin, Graham
2017-06-01
The fixed points of the International Temperature Scale of 1990 (ITS-90) are the basis of the calibration of standard platinum resistance thermometers (SPRTs). Impurities in the fixed point material at the level of parts per million can give rise to an elevation or depression of the fixed point temperature of order of millikelvins, which often represents the most significant contribution to the uncertainty of SPRT calibrations. A number of methods for correcting for the effect of impurities have been advocated, but it is becoming increasingly evident that no single method can be used in isolation. In this investigation, a suite of five aluminium fixed point cells (defined ITS-90 freezing temperature 660.323 °C) have been constructed, each cell using metal sourced from a different supplier. The five cells have very different levels and types of impurities. For each cell, chemical assays based on the glow discharge mass spectroscopy (GDMS) technique have been obtained from three separate laboratories. In addition a series of high quality, long duration freezing curves have been obtained for each cell, using three different high quality SPRTs, all measured under nominally identical conditions. The set of GDMS analyses and freezing curves were then used to compare the different proposed impurity correction methods. It was found that the most consistent corrections were obtained with a hybrid correction method based on the sum of individual estimates (SIE) and overall maximum estimate (OME), namely the SIE/Modified-OME method. Also highly consistent was the correction technique based on fitting a Scheil solidification model to the measured freezing curves, provided certain well defined constraints are applied. Importantly, the most consistent methods are those which do not depend significantly on the chemical assay.
Freezing and thawing or freezing, thawing, and aging effects on beef tenderness.
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
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.
Segre, Lisa S; Brock, Rebecca L; O'Hara, Michael W
2015-04-01
Depression in low-income, ethnic-minority women of childbearing age is prevalent and compromises infant and child development. Yet numerous barriers prevent treatment delivery. Listening Visits (LV), an empirically supported intervention developed for delivery by British home-visiting nurses, could address this unmet mental health need. This randomized controlled trial (RCT) evaluated the effectiveness of LV delivered at a woman's usual point-of-care, including home visits or an ob-gyn office. Listening Visits were delivered to depressed pregnant women or mothers of young children by their point-of-care provider (e.g., home visitor or physician's assistant), all of whom had low levels of prior counseling experience. Three quarters of the study's participants were low-income. Of those who reported ethnicity, all identified themselves as minorities. Participants from 4 study sites (N = 66) were randomized in a 2:1 ratio, to LV or a wait-list control group (WLC). Assessments, conducted at baseline and 8 weeks, evaluated depression, quality of life, and treatment satisfaction. Depressive severity, depressive symptoms, and quality of life significantly improved among LV recipients as compared with women receiving standard social/health services. Women valued LV as evidenced by their high attendance rates and treatment satisfaction ratings. In a stepped model of depression care, LV can provide an accessible, acceptable, and effective first-line treatment option for at-risk women who otherwise are unlikely to receive treatment. (PsycINFO Database Record (c) 2015 APA, all rights reserved).
NASA Astrophysics Data System (ADS)
Kingett, Christian; Ahmadi, Farzad; Nath, Saurabh; Boreyko, Jonathan
2017-11-01
The two-stage freezing process of a liquid droplet on a substrate is well known; however, how bubbles freeze has not yet been studied. We first deposited bubbles on a silicon substrate that was chilled at temperatures ranging from -10 °C to -40 °C, while the air was at room temperature. We observed that the freeze front moved very slowly up the bubble, and in some cases, even came to a complete halt at a critical height. This slow freezing front propagation can be explained by the low thermal conductivity of the thin soap film, and can be observed more clearly when the bubble size or the surface temperature is increased. This delayed freezing allows the frozen portion of the bubble to cool the air within the bubble while the top part is still liquid, which induces a vapor pressure mismatch that either collapses the top or causes the top to pop. In cases where the freeze front reaches the top of the bubble, a portion of the top may melt and slowly refreeze; this can happen more than just once for a single bubble. We also investigated freezing bubbles inside of a freezer where the air was held at -20 °C. In this case, the bubbles freeze quickly and the ice grows radially from nucleation sites instead of perpendicular to the surface, which provides a clear contrast with the conduction limited room temperature bubbles.
Freezing and melting water in lamellar structures.
Gleeson, J T; Erramilli, S; Gruner, S M
1994-01-01
The manner in which ice forms in lamellar suspensions of dielaidoylphosphatidylethanolamine, dielaidoylphosphatidylcholine, and dioleoylphosphatidylcholine in water depends strongly on the water fraction. For weight fractions between 15 and 9%, the freezing and melting temperatures are significantly depressed below 0 degree C. The ice exhibits a continuous melting transition spanning as much as 20 degrees C. When the water weight fraction is below 9%, ice never forms at temperatures as low as -40 degrees C. We show that when water contained in a lamellar lipid suspension freezes, the ice is not found between the bilayers; it exists as pools of crystalline ice in equilibrium with the bound water associated with the polar lipid headgroups. We have used this effect, together with the known chemical potential of ice, to measure hydration forces between lipid bilayers. We find exponentially decaying hydration repulsion when the bilayers are less than about 7 A apart. For larger separations, we find significant deviations from single exponential decay. PMID:7948683
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.
Hepatitis B vaccine freezing in the Indonesian cold chain: evidence and solutions.
Nelson, Carib M; Wibisono, Hariadi; Purwanto, Hary; Mansyur, Isa; Moniaga, Vanda; Widjaya, Anton
2004-02-01
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. 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. 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. 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.
Synchrotron X-Ray Visualisation of Ice Formation in Insects during Lethal and Non-Lethal Freezing
Sinclair, Brent J.; Gibbs, Allen G.; Lee, Wah-Keat; Rajamohan, Arun; Roberts, Stephen P.; Socha, John J.
2009-01-01
Although the biochemical correlates of freeze tolerance in insects are becoming well-known, the process of ice formation in vivo is subject to speculation. We used synchrotron x-rays to directly visualise real-time ice formation at 3.3 Hz in intact insects. We observed freezing in diapausing 3rd instar larvae of Chymomyza amoena (Diptera: Drosophilidae), which survive freezing if it occurs above −14°C, and non-diapausing 3rd instar larvae of C. amoena and Drosophila melanogaster (Diptera: Drosophilidae), neither of which survive freezing. Freezing was readily observed in all larvae, and on one occasion the gut was seen to freeze separately from the haemocoel. There were no apparent qualitative differences in ice formation between freeze tolerant and non-freeze tolerant larvae. The time to complete freezing was positively related to temperature of nucleation (supercooling point, SCP), and SCP declined with decreasing body size, although this relationship was less strong in diapausing C. amoena. Nucleation generally occurred at a contact point with the thermocouple or chamber wall in non-diapausing larvae, but at random in diapausing larvae, suggesting that the latter have some control over ice nucleation. There were no apparent differences between freeze tolerant and non-freeze tolerant larvae in tracheal displacement or distension of the body during freezing, although there was markedly more distension in D. melanogaster than in C. amoena regardless of diapause state. We conclude that although control of ice nucleation appears to be important in freeze tolerant individuals, the physical ice formation process itself does not differ among larvae that can and cannot survive freezing. This suggests that a focus on cellular and biochemical mechanisms is appropriate and may reveal the primary adaptations allowing freeze tolerance in insects. PMID:20011523
Freeze for action: neurobiological mechanisms in animal and human freezing
2017-01-01
Upon increasing levels of threat, animals activate qualitatively different defensive modes, including freezing and active fight-or-flight reactions. Whereas freezing is a form of behavioural inhibition accompanied by parasympathetically dominated heart rate deceleration, fight-or-flight reactions are associated with sympathetically driven heart rate acceleration. Despite the potential relevance of freezing for human stress-coping, its phenomenology and neurobiological underpinnings remain largely unexplored in humans. Studies in rodents have shown that freezing depends on amygdala projections to the brainstem (periaqueductal grey). Recent neuroimaging studies in humans have indicated that similar brain regions may be involved in human freezing. In addition, flexibly shifting between freezing and active defensive modes is critical for adequate stress-coping and relies on fronto-amygdala connections. This review paper presents a model detailing these neural mechanisms involved in freezing and the shift to fight-or-flight action. Freezing is not a passive state but rather a parasympathetic brake on the motor system, relevant to perception and action preparation. Study of these defensive responses in humans may advance insights into human stress-related psychopathologies characterized by rigidity in behavioural stress reactions. The paper therefore concludes with a research agenda to stimulate translational animal–human research in this emerging field of human defensive stress responses. This article is part of the themed issue ‘Movement suppression: brain mechanisms for stopping and stillness’. PMID:28242739
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. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
Colloid-facilitated mobilization of metals by freeze-thaw cycles.
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.
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
A comparison of freezing-damage during isochoric and isobaric freezing of the potato.
Lyu, Chenang; Nastase, Gabriel; Ukpai, Gideon; Serban, Alexandru; Rubinsky, Boris
2017-01-01
Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freezing may be reduced in an isochoric freezing system. To explore this hypothesis, we performed a preliminary study on the isochoric freezing of a produce with which our group has experience, the potato. Experiments were performed in an isochoric freezing device we designed. The device is robust and has no moving parts. For comparison, we used a geometrically identical isobaric freezing device. Following freezing and thawing, the samples were weighed, examined with colorimetry, and examined with microscopy. It was found that potatoes frozen to -5 °C in an isochoric system experienced no weight loss and limited enzymatic browning. In contrast the -5 °C isobaric frozen potato experienced substantial weight loss and substantial enzymatic browning. Microscopic analysis shows that the structural integrity of the potato is maintained after freezing in the isochoric system and impaired after freezing in the isobaric system. Tissue damage during isobaric freezing is caused by the increase in extracellular osmolality and the mechanical damage by ice crystals. Our thermodynamic analysis predicts that during isochoric freezing the intracellular osmolality remains comparable to the extracellular osmolality and that isochoric systems can be designed to eliminate the mechanical damage by ice. The results of this preliminary study seem to confirm the theoretical predictions. This is a preliminary exploratory study on isochoric freezing of food. We have shown that the quality of a food product preserved
Kinetic freeze-out conditions for the production of resonances, hadronic molecules, and light nuclei
NASA Astrophysics Data System (ADS)
Cho, Sungtae; Song, Taesoo; Lee, Su Houng
2018-02-01
We investigate the freeze-out conditions of a particle in an expanding system of interacting particles in order to understand the productions of resonances, hadronic molecules, and light nuclei in heavy-ion collisions. Applying the kinetic freeze-out condition with explicit hydrodynamic calculations for the expanding hadronic phase to the daughter particles of K* mesons, we find that the larger suppression of the yield ratio of K*/K at the Large Hadron Collider (LHC) than at the Relativisitic Heavy Ion Collider (RHIC) compared to the expectations from the statistical hadronization model based on chemical freeze-out parameters reflects the lower kinetic freeze-out temperature at LHC than at RHIC. Furthermore, we point out that for the light nuclei or hadronic molecules that are bound, the freeze-out condition should be applied to the respective particle in the hadronic matter. It is then shown through the rate equation that when the nucleon and pion numbers are kept constant at the chemical freeze-out value during the hadronic phase, the deuteron number quickly approaches an asymptotic value that is close to the statistical model prediction at the chemical freeze-out point. We argue that the reduction seen in K* numbers is a typical result for a particle that has a large natural decay width decaying into daughter particles, while that for deuteron is typical for a stable hadronic bound state.
A comparison of freezing-damage during isochoric and isobaric freezing of the potato
Serban, Alexandru; Rubinsky, Boris
2017-01-01
Background Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freezing may be reduced in an isochoric freezing system. To explore this hypothesis, we performed a preliminary study on the isochoric freezing of a produce with which our group has experience, the potato. Method Experiments were performed in an isochoric freezing device we designed. The device is robust and has no moving parts. For comparison, we used a geometrically identical isobaric freezing device. Following freezing and thawing, the samples were weighed, examined with colorimetry, and examined with microscopy. Results It was found that potatoes frozen to −5 °C in an isochoric system experienced no weight loss and limited enzymatic browning. In contrast the −5 °C isobaric frozen potato experienced substantial weight loss and substantial enzymatic browning. Microscopic analysis shows that the structural integrity of the potato is maintained after freezing in the isochoric system and impaired after freezing in the isobaric system. Discussion Tissue damage during isobaric freezing is caused by the increase in extracellular osmolality and the mechanical damage by ice crystals. Our thermodynamic analysis predicts that during isochoric freezing the intracellular osmolality remains comparable to the extracellular osmolality and that isochoric systems can be designed to eliminate the mechanical damage by ice. The results of this preliminary study seem to confirm the theoretical predictions. Conclusion This is a preliminary exploratory study on isochoric freezing of food. We have
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.
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.
To freeze or not to freeze embryos: clarity, confusion and conflict.
Goswami, Mohar; Murdoch, Alison P; Haimes, Erica
2015-06-01
Although embryo freezing is a routine clinical practice, there is little contemporary evidence on how couples make the decision to freeze their surplus embryos, or of their perceptions during that time. This article describes a qualitative study of 16 couples who have had in vitro fertilisation (IVF) treatment. The study question was 'What are the personal and social factors that patients consider when deciding whether to freeze embryos?' We show that while the desire for a baby is the dominant drive, couples' views revealed more nuanced and complex considerations in the decision-making process. It was clear that the desire to have a baby influenced couples' decision-making and that they saw freezing as 'part of the process'. However, there were confusions associated with the term 'freezing' related to concerns about the safety of the procedure. Despite being given written information, couples were confused about the practical aspects of embryo freezing, which suggests they were preoccupied with the immediate demands of IVF. Couples expressed ethical conflicts about freezing 'babies'. We hope the findings from this study will inform clinicians and assist them in providing support to couples confronted with this difficult decision-making.
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.
Neuropathy in non-freezing cold injury (trench foot).
Irwin, M S; Sanders, R; Green, C J; Terenghi, G
1997-01-01
Non-freezing cold injury (trench foot) is characterized, in severe cases, by peripheral nerve damage and tissue necrosis. Controversy exists regarding the susceptibility of nerve fibre populations to injury as well as the mechanism of injury. Clinical and histological studies (n = 2) were conducted in a 40-year-old man with severe non-freezing cold injury in both feet. Clinical sensory tests, including two-point discrimination and pressure, vibration and thermal thresholds, indicated damage to large and small diameter nerves. On immunohistochemical assessment, terminal cutaneous nerve fibres within the plantar skin stained much less than in a normal control whereas staining to von Willebrand factor pointed to increased vascularity in all areas. The results indicate that all nerve populations (myelinated and unmyelinated) were damaged, possibly in a cycle of ischaemia and reperfusion. Images Figure 1 a Figure 1 b Figure 2 a Figure 2 b Figure 3 a Figure 3 b PMID:9306996
Freezing during tapping tasks in patients with advanced Parkinson's disease and freezing of gait.
Delval, Arnaud; Defebvre, Luc; Tard, Céline
2017-01-01
Parkinson's disease patients with freezing of gait also experience sudden motor blocks (freezing) during other repetitive motor tasks. We assessed the proportion of patients with advanced PD and freezing of gait who also displayed segmental "freezing" in tapping tasks. Fifteen Parkinson's disease patients with freezing of gait were assessed. Freezing of gait was evaluated using a standardized gait trajectory with the usual triggers. Patients performed repetitive tapping movements (as described in the MDS-UPDRS task) with the hands or the feet in the presence or absence of a metronome set to 4 Hz. Movements were recorded with a video motion system. The primary endpoint was the occurrence of segmental freezing in these tapping tasks. The secondary endpoints were (i) the relationship between segmental episodic phenomena and FoG severity, and (ii) the reliability of the measurements. For the upper limbs, freezing was observed more frequently with a metronome (21% of trials) than without a metronome (5%). For the lower limbs, the incidence of freezing was higher than for the upper limbs, and was again observed more frequently in the presence of an auditory cue (47%) than in its absence (14%). Although freezing of the lower limbs was easily assessed during an MDS-UPDRS task with a metronome, it was not correlated with the severity of freezing of gait (as evaluated during a standardized gait trajectory). Only this latter was a reliable measurement in patients with advanced Parkinson's disease.
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.
Freezing in the Antarctic limpet, Nacella concinna.
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. (c) 2010 Elsevier Inc. All rights reserved.
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.
A hyperactive, Ca2+-dependent antifreeze protein in an Antarctic bacterium.
Gilbert, Jack A; Davies, Peter L; Laybourn-Parry, Johanna
2005-04-01
In cold climates, some plants and bacteria that cannot avoid freezing use antifreeze proteins (AFPs) to lessen the destructive effects of ice recrystallization. These AFPs have weak freezing point depression activity, perhaps to avoid sudden, uncontrolled growth of ice. Here, we report on an uncharacteristically powerful bacterial AFP found in an Antarctic strain of the bacterium, Marinomonas primoryensis. It is Ca(2+)-dependent, shows evidence of cooperativity, and can produce over 2 degrees C of freezing point depression. Unlike most AFPs, it does not produce obvious crystal faceting during thermal hysteresis. This AFP might be capable of imparting freezing avoidance to M. primoryensis in ice-covered Antarctic lakes. A hyperactive bacterial AFP has not previously been reported.
Zhang, Peizhi; Zhu, Zhiwei; Sun, Da-Wen
2018-05-31
Freezing is an effective way of food preservation. However, traditional freezing methods have the disadvantages of low freezing efficiency and generation of large ice crystals, leading to possible damage of food quality. Power ultrasound assisted freezing as a novel technique can effectively reduce the adverse effects during freezing process. This paper gives an overview on recent researches of power ultrasound technique to accelerate the food freezing processes and illustrates the main principles of power ultrasound assisted freezing. The effects of power ultrasound on liquid food, model solid food as well as fruit and vegetables are discussed, respectively, from the aspects of increasing freezing rate and improving microstructure. It is shown that ultrasound assisted freezing can effectively improve the freezing efficiency and promote the formation of small and evenly distributed ice crystals, resulting in better food quality. Different inherent properties of food samples affect the effectiveness of ultrasound application and optimum ultrasound parameters depend on the nature of the samples. The application of ultrasound to the food industry is more likely on certain types of food products and more efforts are still needed to realize the industrial translation of laboratory results.
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.
Freezing of gait is associated with cognitive impairment in patients with Parkinson disease.
Yao, Zhiwen; Shao, Yuan; Han, Xiang
2017-08-24
To explore whether the cognitive impairment is correlated with freezing of gait (FOG) in patients with Parkinson disease (PD). A total of 186 patients with Parkinson disease (104 patients with FOG and 82 patients with no clinical history of freezing behavior) and 125 healthy individuals were selected for this study. Neuropsychological assessments, including the scales for outcomes in Parkinson disease cognition, unified Parkinson's disease rating scale, and Hamilton depression/anxiety rating scale etc., were applied to evaluate the patients'cognitive functioning. We found that the scores of Unified Parkinson's Disease Rating Scale (UPDRS) were significantly higher among PD patients with FOG, compared with non-FOG group. We also showed that Mini-Mental State Examination score (MMSE) was lower among subjects with FOG than in patients without FOG. Patients with FOG displayed lower Scales for OUTCOMES: in Parkinson's Disease Cognition (SCOPA-COG) score than non-FOG patients. In addition, significant higher Hamilton Anxiety Rating Scale (HAMD) scores were found in patients with FOG than patients without FOG. Moreover, disease duration, stage of the disease, the severity of motor symptom, increased depressive and anxiety complaints measured by FOG questionnaire were significantly associated with severity of FOG. Meanwhile, we also found that the score of Freezing of Gait Questionnaire (FOGQ) score was negatively correlated with MMSE. Our results demonstrated that FOG is related to impaired cognitive functions in PD patients with FOG. The understanding of impaired cognitive functions in PD patients with FOG can provide evidences for possible therapeutic interventions. Copyright © 2017 Elsevier B.V. All rights reserved.
Liu, Fanghui; Zargarzadeh, Leila; Chung, Hyun-Joong; Elliott, Janet A W
2017-10-12
Thermodynamic phase behavior is affected by curved interfaces in micro- and nanoscale systems. For example, capillary freezing point depression is associated with the pressure difference between the solid and liquid phases caused by interface curvature. In this study, the thermal, mechanical, and chemical equilibrium conditions are derived for binary solid-liquid equilibrium with a curved solid-liquid interface due to confinement in a capillary. This derivation shows the equivalence of the most general forms of the Gibbs-Thomson and Ostwald-Freundlich equations. As an example, the effect of curvature on solid-liquid equilibrium is explained quantitatively for the water/glycerol system. Considering the effect of a curved solid-liquid interface, a complete solid-liquid phase diagram is developed over a range of concentrations for the water/glycerol system (including the freezing of pure water or precipitation of pure glycerol depending on the concentration of the solution). This phase diagram is compared with the traditional phase diagram in which the assumption of a flat solid-liquid interface is made. We show the extent to which nanoscale interface curvature can affect the composition-dependent freezing and precipitating processes, as well as the change in the eutectic point temperature and concentration with interface curvature. Understanding the effect of curvature on solid-liquid equilibrium in nanoscale capillaries has applications in the food industry, soil science, cryobiology, nanoporous materials, and various nanoscience fields.
Optimization of the secondary drying step in freeze drying using TDLAS technology.
Schneid, Stefan C; Gieseler, Henning; Kessler, William J; Luthra, Suman A; Pikal, Michael J
2011-03-01
The secondary drying phase in freeze drying is mostly developed on a trial-and-error basis due to the lack of appropriate noninvasive process analyzers. This study describes for the first time the application of Tunable Diode Laser Absorption Spectroscopy, a spectroscopic and noninvasive sensor for monitoring secondary drying in laboratory-scale freeze drying with the overall purpose of targeting intermediate moisture contents in the product. Bovine serum albumin/sucrose mixtures were used as a model system to imitate high concentrated antibody formulations. First, the rate of water desorption during secondary drying at constant product temperatures (-22 °C, -10 °C, and 0 °C) was investigated for three different shelf temperatures. Residual moisture contents of sampled vials were determined by Karl Fischer titration. An equilibration step was implemented to ensure homogeneous distribution of moisture (within 1%) in all vials. The residual moisture revealed a linear relationship to the water desorption rate for different temperatures, allowing the evaluation of an anchor point from noninvasive flow rate measurements without removal of samples from the freeze dryer. The accuracy of mass flow integration from this anchor point was found to be about 0.5%. In a second step, the concept was successfully tested in a confirmation experiment. Here, good agreement was found for the initial moisture content (anchor point) and the subsequent monitoring and targeting of intermediate moisture contents. The present approach for monitoring secondary drying indicated great potential to find wider application in sterile operations on production scale in pharmaceutical freeze drying. © 2011 American Association of Pharmaceutical Scientists
Lin, Shan-Zhi; Zhang, Zhi-Yi; Liu, Wen-Feng; Lin, Yuan-Zhen; Zhang, Qian; Zhu, Bao-Qing
2005-02-01
To explore the role of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) in the enhancement of freezing resistance induced by freezing acclimation, G6PDH was purified from the leaves of 8-week-old Populus suaveolens cuttings. The G6PDH activity in the absence or the presence of reduced dithiothreitol (DTT(red)) were determined, and the changes in superoxide dismutase (SOD), peroxides (POD) and cytosolic G6PDH activities, malondial-dehyde (MDA) content as well as freezing resistance (expressed as LT(50)) of P. suaveolens cuttings during freezing acclimation at -20 degrees C were investigated. The results showed that the purified G6PDH was probably located in the cytosol of P. suaveolens. Freezing acclimation increased the activities of SOD, POD and cytosolic G6PDH, and decreased the MDA content and LT(50) of cuttings, while 2 d of de-acclimation at 25 degrees C resulted in a decrease in SOD, POD and cytosolic G6PDH activities, and caused an increase in MDA content and LT(50). The change in cytosolic G6PDH activity was found to be closely correlated to the levels of SOD, POD and MDA, and to the degree of freezing resistance of cuttings during freezing acclimation. It is suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation is related to the distinct increase in cytosolic G6PDH activity, which may be involved in the activation of SOD and POD, and the induction of freezing resistance of cuttings.
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
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. Copyright © 2015 Elsevier B.V. All rights reserved.
Freeze-cast alumina pore networks: Effects of freezing conditions and dispersion medium
DOE Office of Scientific and Technical Information (OSTI.GOV)
Miller, S. M.; Xiao, X.; Faber, K. T.
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,more » 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.« less
When a water drop freezes before it solidifies
NASA Astrophysics Data System (ADS)
Kavehpour, Pirouz; Davis, Stephen; Tavakoli, Faryar
2012-11-01
When a drop of liquid is placed on a substrate which temperature is below the melting point of the liquid, one would expect the drop to solidify instantaneously. However, many liquids, such as water, must be subcooled to solidify below its melting temperature due to homogeneous nucleation's high activation energy. Most of the drop solidification research, particularly for water, phase change is assumed to occur at equilibrium freezing temperature; however, this is not the case. We found that after a certain degree of supercooling, a kinetic based nucleation begins and latent heat of fusion is suddenly liberated, causing an increase in liquid temperature. At the end of this stage, approximately 20% of the drop is crystallized. This phenomenon is known among metallurgists as recalescence. This is followed by a slow solidification process at the melting point. As a water droplet spreads on a cold substrate, its contact line stops just prior to freezing inception from the liquid-solid interface. In this study, we assert that recalescence prior to solidification may be the cause of water's sudden immobility, which results in a fixed contact angle and droplet diameter. In our experiments, the nucleation front initiates from the trijunction point and propagates to the drop volume.
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.
Wang, Jun; Apte, Pankaj A; Morris, James R; Zeng, Xiao Cheng
2013-09-21
Stockmayer fluids are a prototype model system for dipolar fluids. We have computed the freezing temperatures of Stockmayer fluids at zero pressure using three different molecular-dynamics simulation methods, namely, the superheating-undercooling method, the constant-pressure and constant-temperature two-phase coexistence method, and the constant-pressure and constant-enthalpy two-phase coexistence method. The best estimate of the freezing temperature (in reduced unit) for the Stockmayer (SM) fluid with the dimensionless dipole moment μ*=1, √2, √3 is 0.656 ± 0.001, 0.726 ± 0.002, and 0.835 ± 0.005, respectively. The freezing temperature increases with the dipolar strength. Moreover, for the first time, the solid-liquid interfacial free energies γ of the fcc (111), (110), and (100) interfaces are computed using two independent methods, namely, the cleaving-wall method and the interfacial fluctuation method. Both methods predict that the interfacial free energy increases with the dipole moment. Although the interfacial fluctuation method suggests a weaker interfacial anisotropy, particularly for strongly dipolar SM fluids, both methods predicted the same trend of interfacial anisotropy, i.e., γ100 > γ110 > γ111.
Freeze Technology for Nuclear Applications - 13590
DOE Office of Scientific and Technical Information (OSTI.GOV)
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 underwatermore » 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)« less
SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato
Wang, Kun; Hersh, Hope Lynn; Benning, Christoph
2016-09-06
SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance ofmore » wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg 2+-dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops.« less
SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato
DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Kun; Hersh, Hope Lynn; Benning, Christoph
SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance ofmore » wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg 2+-dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops.« less
Freezing Injury in Onion Bulb Cells
Palta, Jiwan P.; Levitt, Jacob; Stadelmann, Eduard J.
1977-01-01
Onion (Allium cepa L.) bulbs were subjected for 12 days to either a moderate freeze (−4 C) or a severe freeze (−11 C). They were then thawed slowly over ice. During 7 to 12 days following the thaw, the injury progressed with time in the severely frozen bulbs, but appeared completely repaired in the moderately frozen bulbs. This was shown by the following post-thawing changes. Infiltration of the intercellular spaces increased from 80 to 90% to 100% after the severe freeze, and decreased from 30 to 50% to zero after the moderate freeze. All of the cells were alive immediately after thawing whether the freeze was moderate or severe. Corresponding to the infiltration results 7 to 12 days later, many to most were dead following the severe freeze, all were alive following the moderate freeze. The conductivity of the effusate from pieces of bulb tissue increased after the severe freezing, and decreased after the moderate freezing. The concentration of K+, total solutes, and sugars in the effusate paralleled the conductivity changes. Neither the pH of the effusate nor the permeability of the cells (as long as cells were living) to water was changed following either the severe or the moderate freezes. Some treatments of the thawed tissue following the severe freeze halted the progress of injury. The above results indicate that the semipermeable properties of the cell are uninjured but that the ion and sugar transport mechanism is damaged by freezing. Most likely the primary injury is to the active transport mechanism involved in their transport. It must be concluded that the final injury following freezing and thawing cannot be evaluated from the degree of infiltration or the conductivity of the effusate immediately after thawing, since injury may progress or recede following the thawing. PMID:16660101
Lin, Shan-Zhi; Zhang, Zhi-Yi; Lin, Yuan-Zhen; Zhang, Qian; Guo, Huan
2004-02-01
To explore the role of calcium-calmodulin messenger system in the transduction of low temperature signal in woody plants, Populus tomentosa cuttings after being treated with CaCl(2) (10 mmol/L), Ca(2+) chelator EGTA (3 mmol/L), Ca(2+) channel inhibitor LaCl(3) (100 mmol/L) or CaM antagonist CPZ (50 mmol/L) were used for freezing acclimation at -3 degrees C. The changes in the calmodulin (CaM) and malonaldehyde (MDA) contents, the activities of superoxide dismutase (SOD), peroxidase (POD) and Ca(2+)-dependent adenosinetriphosphatase (Ca(2+)-ATPase) of mitochondrial membrane as well as freezing resistance (expressed as LT(50)) of cuttings were investigated to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation increased the CaM content, the activities of SOD, POD and Ca(2+)-ATPase of mitochondrial membrane as well as freezing resistance of cuttings, and decreased the MDA content as compared with control cuttings. Treatment with CaCl(2) at the time of freezing acclimation enhanced the effect of freezing acclimation on the above-mentioned indexes, but this enhancement was abolished by Ca(2+)chelator EGTA, Ca(2+) channel inhibitor LaCl(3) or CaM antagonist CPZ, indicating that the calcium-calmodulin messenger system was involved in the course of freezing resistance development. The presence of CaCl(2) at the same time of freezing acclimation also reduced the degree of decline in CaM content, and in SOD, POD and Ca(2+)-ATPase activities caused by freezing stress at -14 degrees C, and enhanced the level of increase in CaM content, and in SOD, POD and Ca(2+)-ATPase activity in the recovery periods at 25 degrees C . The change in CaM content was found to be closely correlated to the levels of SOD, POD and Ca(2+)-ATPase, and to the degree of freezing resistance of cuttings during freezing acclimation either with or without CaCl(2) treatment. It was suggested that the increase of CaM content induced by CaCl(2
Gieseler, Henning; Kramer, Tony; Pikal, Michael J
2007-12-01
This report provides, for the first time, a summary of experiments using SMART Freeze Dryer technology during a 9 month testing period. A minimum ice sublimation area of about 300 cm(2) for the laboratory freeze dryer, with a chamber volume 107.5 L, was found consistent with data obtained during previous experiments with a smaller freeze dryer (52 L). Good reproducibility was found for cycle design with different type of excipients, formulations, and vials used. SMART primary drying end point estimates were accurate in the majority of the experiments, but showed an over prediction of primary cycle time when the product did not fully achieve steady state conditions before the first MTM measurement was performed. Product resistance data for 5% sucrose mixtures at varying fill depths were very reproducible. Product temperature determined by SMART was typically in good agreement with thermocouple data through about 50% of primary drying time, with significant deviations occurring near the end of primary drying, as expected, but showing a bias much earlier in primary drying for high solid content formulations (16.6% Pfizer product) and polyvinylpyrrolidone (40 kDa) likely due to water "re-adsorption" by the amorphous product during the MTM test. (c) 2007 Wiley-Liss, Inc.
Non-equilibrium freezing behaviour of aqueous systems.
MacKenzie, A P
1977-03-29
The tendencies to non-equilibrium freezing behaviour commonly noted in representative aqueous systems derive from bulk and surface properties according to the circumstances. Supercooling and supersaturation are limited by heterogeneous nucleation in the presence of solid impurities. Homogeneous nucleation has been observed in aqueous systems freed from interfering solids. Once initiated, crystal growth is ofter slowed and, very frequently, terminated with increasing viscosity. Nor does ice first formed always succeed in assuming its most stable crystalline form. Many of the more significant measurements on a given systeatter permitting the simultaneous representation of thermodynamic and non-equilibrium properties. The diagram incorporated equilibrium melting points, heterogeneous nucleation temperatures, homogeneous nucleation temperatures, glass transition and devitrification temperatures, recrystallization temperatures, and, where appropriate, solute solubilities and eutectic temperatures. Taken together, the findings on modle systems aid the identification of the kinetic and thermodynamic factors responsible for the freezing-thawing survival of living cells.
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…
Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy
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...
Fundamental technical elements of freeze-fracture/freeze-etch in biological electron microscopy.
Carson, Johnny L
2014-09-11
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.
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.
Influence of the freezing method on the changes that occur in grape samples after frozen storage.
Santesteban, Luis G; Miranda, Carlos; Royo, José B
2013-09-01
Sample freezing is frequently used in oenological laboratories as a compromise solution to increase the number of samples that can be analysed, despite the fact that some grape characteristics are known to change after frozen storage. However, freezing is usually performed using standard freezers, which provide a slow freezing. The aim of this work was to evaluate whether blast freezing would decrease the impact of standard freezing on grape composition. Grape quality parameters were assessed in fresh and in frozen stored samples that had been frozen using three different procedures: standard freezing and blast freezing using either a blast freezer or an ultra-freezer. The implications of frozen storage in grape samples reported in earlier research were observed for the three freezing methods evaluated. Although blast freezing improved repeatability for the most problematic parameters (tartaric acidity, TarA; total phenolics, TP), the improvement was not important from a practical point of view. However, TarA and TP were relatively repeatable among the three freezing procedures, which suggests that freezing had an effect on these parameters independently of the method used . According to our results, the salification potential of the must is probably implied in the changes observed for TarA, whereas for TP the precipitation of protoanthocyanins after association with cell wall material is hypothesized to cause the lack of repeatability between fresh and frozen grapes. Blast freezing would not imply a great improvement if implemented in oenological laboratories, at least for the parameters included in this study. © 2013 Society of Chemical Industry.
New particle dependant parameterizations of heterogeneous freezing processes.
NASA Astrophysics Data System (ADS)
Diehl, Karoline; Mitra, Subir K.
2014-05-01
For detailed investigations of cloud microphysical processes an adiabatic air parcel model with entrainment is used. It represents a spectral bin model which explicitly solves the microphysical equations. The initiation of the ice phase is parameterized and describes the effects of different types of ice nuclei (mineral dust, soot, biological particles) in immersion, contact, and deposition modes. As part of the research group INUIT (Ice Nuclei research UnIT), existing parameterizations have been modified for the present studies and new parameterizations have been developed mainly on the basis of the outcome of INUIT experiments. Deposition freezing in the model is dependant on the presence of dry particles and on ice supersaturation. The description of contact freezing combines the collision kernel of dry particles with the fraction of frozen drops as function of temperature and particle size. A new parameterization of immersion freezing has been coupled to the mass of insoluble particles contained in the drops using measured numbers of ice active sites per unit mass. Sensitivity studies have been performed with a convective temperature and dew point profile and with two dry aerosol particle number size distributions. Single and coupled freezing processes are studied with different types of ice nuclei (e.g., bacteria, illite, kaolinite, feldspar). The strength of convection is varied so that the simulated cloud reaches different levels of temperature. As a parameter to evaluate the results the ice water fraction is selected which is defined as the relation of the ice water content to the total water content. Ice water fractions between 0.1 and 0.9 represent mixed-phase clouds, larger than 0.9 ice clouds. The results indicate the sensitive parameters for the formation of mixed-phase and ice clouds are: 1. broad particle number size distribution with high number of small particles, 2. temperatures below -25°C, 3. specific mineral dust particles as ice nuclei such
Vollrath, Ilona; Pauli, Victoria; Friess, Wolfgang; Freitag, Angelika; Hawe, Andrea; Winter, Gerhard
2017-05-01
This study investigates the suitability of heat flux measurement as a new technique for monitoring product temperature and critical end points during freeze drying. The heat flux sensor is tightly mounted on the shelf and measures non-invasively (no contact with the product) the heat transferred from shelf to vial. Heat flux data were compared to comparative pressure measurement, thermocouple readings, and Karl Fischer titration as current state of the art monitoring techniques. The whole freeze drying process including freezing (both by ramp freezing and controlled nucleation) and primary and secondary drying was considered. We found that direct measurement of the transferred heat enables more insights into thermodynamics of the freezing process. Furthermore, a vial heat transfer coefficient can be calculated from heat flux data, which ultimately provides a non-invasive method to monitor product temperature throughout primary drying. The end point of primary drying determined by heat flux measurements was in accordance with the one defined by thermocouples. During secondary drying, heat flux measurements could not indicate the progress of drying as monitoring the residual moisture content. In conclusion, heat flux measurements are a promising new non-invasive tool for lyophilization process monitoring and development using energy transfer as a control parameter. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.
The relationship between latent trigger points and depression levels in healthy subjects.
Celik, Derya; Kaya Mutlu, Ebru
2012-06-01
Our purpose was to study the relationship between latent trigger points (LTrP) and levels of depression in healthy subjects. A total of 76 healthy subjects consisting of 40 men and 36 women (mean age, 25.4 ± 4.8 years; age range, 19-42 years) from the School of Physical Therapy and Rehabilitation and the Orthopaedics and Traumatology Department of Istanbul University Medical Faculty were selected for the study. Latent trigger points on the scapular muscles of each subject were evaluated. The upper and middle trapezius, supraspinatus, serratus anterior, and rhomboideus muscles were examined respectively, by palpation with the thumb, to determine whether there was pain. The first group consisted of 30 subjects (20 men and 10 women; mean age, 24.2 ± 5.02 years) who had previously been diagnosed as negative after an LTrP examination (control group), while the second group consisted of 28 subjects (12 men and 16 women; mean age, 23.6 ± 2.24 years) who had been diagnosed with at least five LTrPs. The third group consisted of 18 subjects (8 men and 10 women; mean age, 26. 9 ± 7.23 years) who had been diagnosed with more than five LTrPs. All groups were assessed, using the Beck Depression Inventory (BDI). The mean BDI value was found to be 8.0 ± 4.2 in the first group, 10.3 ± 3.4 in the second, and 28.5 ± 4.8 in the third. A significant difference was found between the mean BDI values of the first and second groups and also between the first and third groups. The mean BDI values of the second and third groups were also found to be statistically significant (p = 0.042). We observed a close relationship between the presence of LTrPs and depression levels in healthy people.
Large scale synthesis of nanostructured zirconia-based compounds from freeze-dried precursors
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gomez, A.; Villanueva, R.; Vie, D.
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 themore » 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.« less
Polak, Roberta; Pitombo, Ronaldo N M
2011-10-01
Bovine pericardium (BP) tissue is widely used in the manufacture of bioprosthetics. The effects of freeze-drying on the BP tissue have been studied by some researchers in order to decrease their cytotoxicity due to preservation in formaldehyde solution, and to increase the lifetime of the product in storage. This study was undertaken in order to study the effect of freeze-drying in the structure of BP. To perform this study BP samples were freeze-dried in two different types of freeze-dryers available in our laboratory: a laboratory freeze-dryer, in which it was not possible to control parameters and a pilot freeze-dryer, wherein all parameters during freezing and drying were controlled. After freeze-drying processes, samples were analyzed by SEM, Raman spectroscopy, tensile strength, water uptake tests and TEM. In summary, it has been demonstrated that damages occur in collagen fibers by the loss of bulk water of collagen structure implicating in a drastic decreasing of BP mechanical properties due to its structural alterations. Moreover, it was proven that the collagen fibrils suffered breakage at some points, which can be attributed to the uncontrolled parameters during drying. Copyright © 2011 Elsevier Inc. All rights reserved.
In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles
NASA Astrophysics Data System (ADS)
Li, Yingxuan; Zang, Ling; Jacobs, Daniel L.; Zhao, Jie; Yue, Xiu; Wang, Chuanyi
2017-02-01
Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction-relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes.
In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles.
Li, Yingxuan; Zang, Ling; Jacobs, Daniel L; Zhao, Jie; Yue, Xiu; Wang, Chuanyi
2017-02-13
Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi 2 Ta 2 O 9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction-relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes.
In situ study on atomic mechanism of melting and freezing of single bismuth nanoparticles
Li, Yingxuan; Zang, Ling; Jacobs, Daniel L.; Zhao, Jie; Yue, Xiu; Wang, Chuanyi
2017-01-01
Experimental study of the atomic mechanism in melting and freezing processes remains a formidable challenge. We report herein on a unique material system that allows for in situ growth of bismuth nanoparticles from the precursor compound SrBi2Ta2O9 under an electron beam within a high-resolution transmission electron microscope (HRTEM). Simultaneously, the melting and freezing processes within the nanoparticles are triggered and imaged in real time by the HRTEM. The images show atomic-scale evidence for point defect induced melting, and a freezing mechanism mediated by crystallization of an intermediate ordered liquid. During the melting and freezing, the formation of nucleation precursors, nucleation and growth, and the relaxation of the system, are directly observed. Based on these observations, an interaction–relaxation model is developed towards understanding the microscopic mechanism of the phase transitions, highlighting the importance of cooperative multiscale processes. PMID:28194017
Representative Values of Icing-Related Variables Aloft in Freezing Rain and Freezing Drizzle
DOT National Transportation Integrated Search
1996-03-01
Radiosonde and surface observations in freezing rain (ZR) and freezing drizzle (ZL), and a limited number of aircraft measurements in ZR, have been examined for information on the magnitude and altitude dependence of meteorological variables associat...
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.
Cheng, Lina; Sun, Da-Wen; Zhu, Zhiwei; Zhang, Zhihang
2017-08-15
Effects of protein denaturation caused by high pressure freezing, involving Pressure-Factors (pressure, time) and Freezing-Factors (temperature, phase transition, recrystallization, ice crystal types), are complicated. In the current study, the conformation and functional changes of natural actomyosin (NAM) under pressure assisted freezing (PAF, 100,150,300,400,500MPa P -20°C/25min ), pressure shift freezing (PSF, 200MPa P -20°C/25min ), and immersion freezing ( 0.1MPa P -20°C/5min ) after pressure was released to 0.1MPa, as compared to normal immersion freezing process (IF, 0.1MPa P -20°C/30min ). Results indicated that PSF ( 200MPa P -20°C/30min ) could reduce the denaturation of frozen NAM and a pressure of 300MPa was the critical point to induce such a denaturation. During the periods of B→D in PSF or B→C→D in PAF, the generation and growth of ice crystals played an important role on changing the secondary and tertiary structure of the treated NAM. Copyright © 2017 Elsevier Ltd. All rights reserved.
SENSITIVE TO FREEZING2 Aids in Resilience to Salt and Drought in Freezing-Sensitive Tomato1[OPEN
Hersh, Hope Lynn
2016-01-01
SENSITIVE TO FREEZING2 (SFR2) is crucial for protecting chloroplast membranes following freezing in Arabidopsis (Arabidopsis thaliana). It has been shown that SFR2 homologs are present in all land plants, including freezing-sensitive species, raising the question of SFR2 function beyond freezing tolerance. Similar to freezing, salt and drought can cause dehydration. Thus, it is hypothesized that in freezing-sensitive plants SFR2 may play roles in their resilience to salt or drought. To test this hypothesis, SlSFR2 RNAi lines were generated in the cold/freezing-sensitive species tomato (Solanum lycopersicum [M82 cv]). Hypersensitivity to salt and drought of SlSFR2-RNAi lines was observed. Higher tolerance of wild-type tomatoes was correlated with the production of trigalactosyldiacylglycerol, a product of SFR2 activity. Tomato SFR2 in vitro activity is Mg2+-dependent and its optimal pH is 7.5, similar to that of Arabidopsis SFR2, but the specific activity of tomato SFR2 in vitro is almost double that of Arabidopsis SFR2. When salt and drought stress were applied to Arabidopsis, no conditions could be identified at which SFR2 was induced prior to irreversibly impacting plant growth, suggesting that SFR2 protects Arabidopsis primarily against freezing. Discovery of tomato SFR2 function in drought and salt resilience provides further insights into general membrane lipid remodeling-based stress tolerance mechanisms and together with protection against freezing in freezing-resistant plants such as Arabidopsis, it adds lipid remodeling as a possible target for the engineering of abiotic stress-resilient crops. PMID:27600812
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…
Freezing: an underutilized food safety technology?
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.
Freezing and thawing or freezing, thawing, and aging effects on beef tenderness
USDA-ARS?s Scientific Manuscript database
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) ...
De Beer, T R M; Allesø, M; Goethals, F; Coppens, A; Heyden, Y Vander; De Diego, H Lopez; Rantanen, J; Verpoort, F; Vervaet, C; Remon, J P; Baeyens, W R G
2007-11-01
The aim of the present study was to propose a strategy for the implementation of a Process Analytical Technology system in freeze-drying processes. Mannitol solutions, some of them supplied with NaCl, were used as models to freeze-dry. Noninvasive and in-line Raman measurements were continuously performed during lyophilization of the solutions to monitor real time the mannitol solid state, the end points of the different process steps (freezing, primary drying, secondary drying), and physical phenomena occurring during the process. At-line near-infrared (NIR) and X-ray powder diffractometry (XRPD) measurements were done to confirm the Raman conclusions and to find out additional information. The collected spectra during the processes were analyzed using principal component analysis and multivariate curve resolution. A two-level full factorial design was used to study the significant influence of process (freezing rate) and formulation variables (concentration of mannitol, concentration of NaCl, volume of freeze-dried sample) upon freeze-drying. Raman spectroscopy was able to monitor (i) the mannitol solid state (amorphous, alpha, beta, delta, and hemihydrate), (ii) several process step end points (end of mannitol crystallization during freezing, primary drying), and (iii) physical phenomena occurring during freeze-drying (onset of ice nucleation, onset of mannitol crystallization during the freezing step, onset of ice sublimation). NIR proved to be a more sensitive tool to monitor sublimation than Raman spectroscopy, while XRPD helped to unravel the mannitol hemihydrate in the samples. The experimental design results showed that several process and formulation variables significantly influence different aspects of lyophilization and that both are interrelated. Raman spectroscopy (in-line) and NIR spectroscopy and XRPD (at-line) not only allowed the real-time monitoring of mannitol freeze-drying processes but also helped (in combination with experimental design) us
NASA Astrophysics Data System (ADS)
Pardo, R.; Berg, A. A.; Warland, J. S.
2017-12-01
The use of microwave remote sensing for surface ground ice detection has been well documented using both active and passive systems. Typical validation of these remotely sensed F/T state products relies on in-situ air or soil temperature measurements and a threshold of 0°C to identify frozen soil. However, in soil pores, the effects of capillary and adsorptive forces combine with the presence of dissolved salts to depress the freezing point. This is further confounded by the fact that water over this temperature range releases/absorbs latent heat of freezing/fusion. Indeed, recent results from SLAPEx2015, a campaign conducted to evaluate the ability to detect F/T state and examine the controls on F/T detection at multiple resolutions, suggest that using a soil temperature of 0°C as a threshold for freezing may not be appropriate. Coaxial impedance sensors, like Steven's HydraProbeII (HP), are the most widely used soil sensor in water supply forecast and climatological networks. These soil moisture probes have recently been used to validate remote sensing F/T products. This kind of validation is still relatively uncommon and dependent on categorical techniques based on seasonal reference states of frozen and non-frozen soil conditions. An experiment was conducted to identify the correlation between the phase state of the soil moisture and the probe measurements. Eight soil cores were subjected to F/T transitions in an environmental chamber. For each core, at a depth of 2.5 cm, the temperature and real dielectric constant (rdc) were measured every five minutes using HPs while two heat pulse probes captured the apparent heat capacity 24 minutes apart. Preliminary results show the phase transition of water is bounded by inflection points in the soil temperature, attributed to latent heat. The rdc, however, appears to be highly sensitive to changes in the water preceding the phase change. This opens the possibility of estimating a dynamic temperature threshold for
Arsiccio, Andrea; Pisano, Roberto
2018-06-01
The present work shows a rational method for the development of the freezing step of a freeze-drying cycle. The current approach to the selection of freezing conditions is still empirical and nonsystematic, thus resulting in poor robustness of control strategy. The final aim of this work is to fill this gap, describing a rational procedure, based on mathematical modeling, for properly choosing the freezing conditions. Mechanistic models are used for the prediction of temperature profiles during freezing and dimension of ice crystals being formed. Mathematical description of the drying phase of freeze-drying is also coupled with the results obtained by freezing models, thus providing a comprehensive characterization of the lyophilization process. In this framework, deep understanding of the phenomena involved is required, and according to the Quality by Design approach, this knowledge can be used to build the design space. The step-by-step procedure for building the design space for freezing is thus described, and examples of applications are provided. The calculated design space is validated upon experimental data, and we show that it allows easy control of the freezing process and fast selection of appropriate operating conditions. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.
Depression affects about 15 million American adults every year. Women are more likely to get depression than men. In general, about one out of every four women will get depression at some point in her life.
Contact Freezing of Water by Salts.
Niehaus, Joseph; Cantrell, Will
2015-09-03
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.
Cognitive Factors Affecting Freeze-like Behavior in Humans.
Alban, Michael W; Pocknell, Victoria
2017-01-01
Contemporary research on survival-related defensive behaviors has identified physiological markers of freeze/flight/fight. Our research focused on cognitive factors associated with freeze-like behavior in humans. Study 1 tested if an explicit decision to freeze is associated with the psychophysiological state of freezing. Heart rate deceleration occurred when participants chose to freeze. Study 2 varied the efficacy of freezing relative to other defense options and found "freeze" was responsive to variations in the perceived effectiveness of alternative actions. Study 3 tested if individual differences in motivational orientation affect preference for a "freeze" option when the efficacy of options is held constant. A trend in the predicted direction suggested that naturally occurring cognitions led loss-avoiders to select "freeze" more often than reward-seekers. In combination, our attention to the cognitive factors affecting freeze-like behavior in humans represents a preliminary step in addressing an important but neglected research area.
Bullen, A.; Taylor, R.R.; Kachar, B.; Moores, C.; Fleck, R.A.; Forge, A.
2014-01-01
In the preservation of tissues in as ‘close to life’ state as possible, rapid freeze fixation has many benefits over conventional chemical fixation. One technique by which rapid freeze-fixation can be achieved, high pressure freezing (HPF), has been shown to enable ice crystal artefact-free freezing and tissue preservation to greater depths (more than 40 μm) than other quick-freezing methods. Despite increasingly becoming routine in electron microscopy, the use of HPF for the fixation of inner ear tissue has been limited. Assessment of the quality of preservation showed routine HPF techniques were suitable for preparation of inner ear tissues in a variety of species. Good preservation throughout the depth of sensory epithelia was achievable. Comparison to chemically fixed tissue indicated that fresh frozen preparations exhibited overall superior structural preservation of cells. However, HPF fixation caused characteristic artefacts in stereocilia that suggested poor quality freezing of the actin bundles. The hybrid technique of pre-fixation and high pressure freezing was shown to produce cellular preservation throughout the tissue, similar to that seen in HPF alone. Pre-fixation HPF produced consistent high quality preservation of stereociliary actin bundles. Optimising the preparation of samples with minimal artefact formation allows analysis of the links between ultrastructure and function in inner ear tissues. PMID:25016142
Freeze-dried spermatozoa: A future tool?
Olaciregui, M; Gil, L
2017-04-01
Cryopreservation has been routinely used to preserve sperm of human and different animal species. However, frozen sperm storage for a long time brings many inconveniences because of liquid nitrogen. Many attempts have been made to overcome the disadvantages of the current cryopreservation method. Freeze-drying has been proposed as alternative method for sperm preservation to achieve the ability to store sperm doses indefinitely at ambient temperature or in ordinary refrigerators. At present, it has been reported successfully sperm freeze-drying on many animal species including canine and feline. It is well known that during freeze-drying process, sperm DNA could be damaged, but if suitable protection is provided, the sperm nucleus could preserve the ability to activate the oocyte and embryos could be generated by intracytoplasmic sperm injection (ICSI). Many factors influence the freeze-drying efficacy, so current researches have been conducted to find strategies to control these factors to maintain the sperm DNA integrity. This review describes the latest method of sperm freeze-drying for practical application in preserving and transporting genetic resources. In addition, the approaches to improve the efficiency of the technique were studied. We demonstrated that the DNA integrity of freeze-dried dog sperm is affected by the composition of the freeze-drying solution as well as the temperature and period of storage. Further studies are necessary to refine freeze-drying protocol in order to protect the DNA and maintain the sperm functionality and obtain offspring from freeze-dried sperm. © 2016 Blackwell Verlag GmbH.
Freeze Tolerance of Nine Zoysiagrass Cultivars Using Natural Cold Acclimation and Freeze Chambers
USDA-ARS?s Scientific Manuscript database
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...
Homogeneous freezing of single sulfuric and nitric acid solution drops levitated in an acoustic trap
NASA Astrophysics Data System (ADS)
Diehl, Karoline; Ettner-Mahl, Matthias; Hannemann, Anke; Mitra, Subir K.
2009-10-01
The freezing temperatures of single supercooled drops of binary and ternary sulfuric and nitric acid solutions were measured while varying the acid concentration. An acoustic levitator was used which allows to freely suspend single solution drops in air without electrical charges thereby avoiding any electrical influences which may affect the freezing process. The drops of typically 500 µm in radius were monitored by a video camera during cooling cycles down to - 85 °C to simulate the upper tropospheric and stratospheric temperature range. The present data confirm that liquid solution droplets can be supercooled far below the equilibrium melting point by approximately 35 °C. They follow the general trend of the expected freezing temperatures for homogeneous ice nucleation.
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
Watson, P F; Martin, I C
1975-04-01
The influence of egg yolk, glycerol and the freezing rate on the survival of ram spermatozoa and on the structure of their acrosomes after freezing was investigated. Egg yolk was shown to be beneficial not only during chilling but also during freezing; of the levels examined, 1-5% gave the greatest protection. Although the presence of glycerol in the diluent improved the survival of spermatozoa, increasing concentrations produced significant deterioration of the acrosomes. With closely controlled linear cooling rates, no overall difference was detected in the survival of spermatozoa frozen at rates between 6 and 24 degrees C per min. However, a significant interaction between freezing rate and the inclusion of glycerol in the diluent showed that glycerol was less important at the highest freezing rate. A sudden cooling phase near to the freezing point following the release of the latent heat of fusion was not detrimental to spermatozoa.
VHF Electrical Properties of Frozen Ground Near Point Barrow, Alaska,
1981-06-01
depth. When temperature is depressed even further, the freez - 3. RFI does not require the ground to be disturbed ing of any remaining adsorbed water will...sky wave Seattle, Washington, at 18.6 kHz. Both instruments propagating from a distant or local transmitter to use a small ferrite -loaded coil to
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.
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.
Modelling Cryovolcanism Due to Subsurface Ocean Freezing on Pluto and Charon
NASA Astrophysics Data System (ADS)
Conrad, J. W.; Nimmo, F.; Singer, K. N.
2016-12-01
The New Horizons spacecraft identified various possible cryovolcanic features on the surfaces of both Pluto and Charon [1]. However, there are major differences between the cryovolcanism on Pluto and Charon. Pluto has two mound-flanked depressions which are possibly cryovolcanic [2], while Charon's putative cryovolcanism is more widespread within its smooth southern plains. If Pluto or Charon have (or had) subsurface oceans, slow refreezing of these oceans would lead to extensional surface tectonics [3,4] and pressurization of the ocean [5]. Sufficiently large pressurization can overcome the overburden pressure and cause an eruption. We applied thermal evolution models based on [3] to determine likely freezing scenarios. Eruptions on Charon are possible under most conditions, and occur after tens of kilometers of freezing of an ice shell initially 100 km thick. This would produce an areal extensional strain of 1%. The implied globally-averaged thickness of erupted material is a few hundred meters and the critical crack width for propagation through the entire ice shell [6] is about half a meter for all eruption scenarios. Eruptions on Pluto require probably unrealistic freezing scenarios, because of the larger body size and higher overburden pressure. We conclude that ocean freezing is a possible source of cryovolcanism on Charon and may explain the smooth plains in its southern hemisphere [1]. Pluto, on the other hand, requires more complex models to explain the putative cryovolcanic features on its surface. [1] Moore et al., Science 351 (2016): 1284-1293. [2] Singer et al., LPSC 47 (2016): 2276 [3] Robuchon and Nimmo, Icarus 216 (2011): 426-439. [4] Hammond et al., GRL 43 (2016). [5] Manga and Wang, GRL 34 (2007). [6] Porco et al., The Astronomical Journal 148 (2014): 45.
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 the...
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 and...
Code of Federal Regulations, 2010 CFR
2010-01-01
... 3 The President 1 2010-01-01 2010-01-01 false Pay Freeze Presidential Documents Other Presidential Documents Memorandum of January 21, 2009 Pay Freeze Memorandum for the Assistant to the President and Chief... the White House staff forgo pay increases until further notice. Accordingly, as a signal of our shared...
Bullen, A; Taylor, R R; Kachar, B; Moores, C; Fleck, R A; Forge, A
2014-09-01
In the preservation of tissues in as 'close to life' state as possible, rapid freeze fixation has many benefits over conventional chemical fixation. One technique by which rapid freeze-fixation can be achieved, high pressure freezing (HPF), has been shown to enable ice crystal artefact-free freezing and tissue preservation to greater depths (more than 40 μm) than other quick-freezing methods. Despite increasingly becoming routine in electron microscopy, the use of HPF for the fixation of inner ear tissue has been limited. Assessment of the quality of preservation showed routine HPF techniques were suitable for preparation of inner ear tissues in a variety of species. Good preservation throughout the depth of sensory epithelia was achievable. Comparison to chemically fixed tissue indicated that fresh frozen preparations exhibited overall superior structural preservation of cells. However, HPF fixation caused characteristic artefacts in stereocilia that suggested poor quality freezing of the actin bundles. The hybrid technique of pre-fixation and high pressure freezing was shown to produce cellular preservation throughout the tissue, similar to that seen in HPF alone. Pre-fixation HPF produced consistent high quality preservation of stereociliary actin bundles. Optimising the preparation of samples with minimal artefact formation allows analysis of the links between ultrastructure and function in inner ear tissues. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.
FIMP dark matter freeze-in gauge mediation and hidden sector
NASA Astrophysics Data System (ADS)
Tsao, Kuo-Hsing
2018-07-01
We explore the dark matter freeze-in mechanism within the gauge mediation framework, which involves a hidden feebly interacting massive particle (FIMP) coupling feebly with the messenger fields while the messengers are still in the thermal bath. The FIMP is the fermionic component of the pseudo-moduli in a generic metastable supersymmetry (SUSY) breaking model and resides in the hidden sector. The relic abundance and the mass of the FIMP are determined by the SUSY breaking scale and the feeble coupling. The gravitino, which is the canonical dark matter candidate in the gauge mediation framework, contributes to the dark matter relic abundance along with the freeze-in of the FIMP. The hidden sector thus becomes two-component with both the FIMP and gravitino lodging in the SUSY breaking hidden sector. We point out that the ratio between the FIMP and the gravitino is determined by how SUSY breaking is communicated to the messengers. In particular when the FIMP dominates the hidden sector, the gravitino becomes the minor contributor in the hidden sector. Meanwhile, the neutralino is assumed to be both the weakly interacting massive particle dark matter candidate in the freeze-out mechanism and the lightest observable SUSY particle. We further find out the neutralino has the sub-leading contribution to the current dark matter relic density in the parameter space of our freeze-in gauge mediation model. Our result links the SUSY breaking scale in the gauge mediation framework with the FIMP freeze-in production rate leading to a natural and predicting scenario for the studies of the dark matter in the hidden sector.
Beirowski, Jakob; Inghelbrecht, Sabine; Arien, Albertina; Gieseler, Henning
2011-05-01
It has been recently reported in the literature that using a fast freezing rate during freeze-drying of drug nanosuspensions is beneficial to preserve the original particle size distribution. All freezing rates studied were obtained by utilizing a custom-made apparatus and were then indirectly related to conventional vial freeze-drying. However, a standard freeze-dryer is only capable of achieving moderate freezing rates in the shelf fluid circulation system. Therefore, it was the purpose of the present study to evaluate the possibility to establish a typical freezing protocol applicable to a standard freeze-drying unit in combination with an adequate choice of cryoprotective excipients and steric stabilizers to preserve the original particle size distribution. Six different drug nanosuspensions containing itraconazole as a drug model were studied using freeze-thaw experiments and a full factorial design to reveal major factors for the stabilization of drug nanosuspensions and the corresponding interactions. In contrast to previous reports, the freezing regime showed no significant influence on preserving the original particle size distribution, suggesting that the concentrations of both the steric stabilizer and the cryoprotective agent are optimized. Moreover, it could be pinpointed that the combined effect of steric stabilizer and cryoprotectant clearly contribute to nanoparticle stability. Copyright © 2010 Wiley-Liss, Inc.
Pharmaceutical patent applications in freeze-drying.
Ekenlebie, Edmond; Einfalt, Tomaž; Karytinos, Arianna Irò; Ingham, Andrew
2016-09-01
Injectable products are often the formulation of choice for new therapeutics; however, formulation in liquids often enhances degradation through hydrolysis. Thus, freeze-drying (lyophilization) is regularly used in pharmaceutical manufacture to reduce water activity. Here we examine its contribution to 'state of the art' and look at its future potential uses. A comprehensive search of patent databases was conducted to characterize the international patent landscape and trends in the use of freeze-drying. A total of 914 disclosures related to freeze-drying, lyophilization or drying of solid systems in pressures and temperatures equivalent to those of freeze-drying were considered over the period of 1992-2014. Current applications of sublimation technology were contrasted across two periods those with patents due to expire (1992-1993) and those currently filed. The number of freeze-drying technology patents has stabilized after initial activity across the biotechnology sector in 2011 and 2012. Alongside an increasing trend for patent submissions, freeze-drying submissions have slowed since 2002 and is indicative of a level of maturity.
Equilibrium, quasi-equilibrium, and nonequilibrium freezing of mammalian embryos.
Mazur, P
1990-08-01
The first successful freezing of early embryos to -196 degrees C in 1972 required that they be cooled slowly at approximately 1 degree C/min to about -70 degrees C. Subsequent observations and physical/chemical analyses indicate that embryos cooled at that rate dehydrate sufficiently to maintain the chemical potential of their intracellular water close to that of the water in the partly frozen extracellular solution. Consequently, such slow freezing is referred to as equilibrium freezing. In 1972 and since, a number of investigators have studied the responses of embryos to departures from equilibrium freezing. When disequilibrium is achieved by the use of higher constant cooling rates to -70 degrees C, the results is usually intracellular ice formation and embryo death. That result is quantitatively in accord with the predictions of the physical/chemical analysis of the kinetics of water loss as a function of cooling rate. However, other procedures involving rapid nonequilibrium cooling do not result in high mortality. One common element in these other nonequilibrium procedures is that, before the temperature has dropped to a level that permits intracellular ice formation, the embryo water content is reduced to the point at which the subsequent rapid nonequilibrium cooling results in either the formation of small innocuous intracellular ice crystals or the conversion of the intracellular solution into a glass. In both cases, high survival requires that subsequent warming be rapid, to prevent recrystallization or devitrification. The physical/chemical analysis developed for initially nondehydrated cells appears generally applicable to these other nonequilibrium procedures as well.
Effects of various freezing containers for vitrification freezing on mouse oogenesis.
Kim, Ji Chul; Kim, Jae Myeoung; Seo, Byoung Boo
2016-01-01
In the present study, various freezing containers were tested for mouse embryos of respective developmental stages; embryos were vitrified and then their survival rate and developmental rate were monitored. Mouse two cell, 8 cell, and blastula stage embryos underwent vitrification freezing-thawing and then their recovery rate, survival rate, development rate, and hatching rate were investigated. EM-grid, OPS, and cryo-loop were utilized for vitrification freezing-thawing of mouse embryos. It was found that recovery rate and survival rate were higher in the group of cryo-loop compared to those of EM-grid (p < 0.05). Embryonic development rate, two cell embryos to blastocyst, as well as hatching rate were higher in the control group compared to the EM-grid group and OPS group (p < 0.05), yet no difference was noted between the control group and cryo-loop group. Development rate and hatching rate of eight cell morulae and blastocysts were all lower in the treatment groups than the control group whilst hatching rate of blastocysts was higher in the control group compared to the groups of EM-grid and OPS (p < 0.05); although the cryo-loop group was shown to be slightly higher than other groups, it was not statistically significant. In the study, we investigate effects of freezing containers on vitrified embryos of respective developmental stages; it was demonstrated that higher developmental rate was shown in more progressed (or developed) embryos with more blastomeres. There was however, no difference in embryonic development rate was shown amongst containers. Taken together, further additional studies are warranted with regards to 1) manipulation techniques of embryos for various vitrification freezing containers and 2) preventive measures against contamination via liquid nitrogen.
Salinas-Rodríguez, Aarón; Manrique-Espinoza, Betty; Acosta-Castillo, Gilberto Isaac; Franco-Núñez, Aurora; Rosas-Carrasco, Oscar; Gutiérrez-Robledo, Luis Miguel; Sosa-Ortiz, Ana Luisa
2014-01-01
To identify a valid cutoff point associated with Center for Epidemiologic Studies, Depression Scale (CES-D) of seven items, which allows the classification of older adults according to presence/absence of clinically significant depressive symptoms. Screening study with 229 older adults residing in two states of Mexico (Morelos and Tlaxcala), which were part of the sample from the National Survey of Health and Nutrition, 2012. We estimated the sensitivity and specificity associated with the selected cutoff points using the diagnostic criteria of ICD-10 (International Classification of Diseases, 10th revision) and DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, fourth edition). The cutoff point estimated was CES-D=5. According to the ICD-10 sensitivity and specificity were 83.3 and 90.2%, and ROC was 87%. Using DSM-IV, the values were 85, 83.2, and 84%, respectively. The short version of the CES-D can be used as a screening test to identify probable cases of older adults with clinically significant depressive symptoms.
High-pressure freezing and freeze substitution of Arabidopsis for electron microscopy.
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.
Moments of the Particle Phase-Space Density at Freeze-out and Coincidence Probabilities
NASA Astrophysics Data System (ADS)
Bialas, A.; Czyż, W.; Zalewski, K.
2005-10-01
It is pointed out that the moments of phase-space particle density at freeze-out can be determined from the coincidence probabilities of the events observed in multiparticle production. A method to measure the coincidence probabilities is described and its validity examined.
Beck, E; Schulze, E D; Senser, M; Scheibe, R
1984-09-01
The water potentials of frozen leaves of Afroalpine plants were measured psychrometrically in the field. Comparison of these potentials with the osmotic potentials of an expressed cellular sap and the water potentials of ice indicated almost ideal freezing behaviour and suggested equilibrium freezing. On the basis of the osmotic potentials of expressed cellular sap, the fractions of frozen cellular water which correspond to the measured water potentials of the frozen leaves could be determined (e.g. 74% at -3.0° C). The freezing points of leaves were found to be in the range between 0° C and -0.5° C, rendering evidence for freezing of almost pure water and thus confirming the conclusions drawn from the water-potential measurements. The leaves proved to be frost resistant down to temperatures between -5° C and -15° C, as depending on the species. They tolerated short supercooling periods which were necessary in order to start ice nucleation. Extracellular ice caps and ice crystals in the intercellular space were observed when cross sections of frozen leaves were investigated microscopically at subfreezing temperatures.
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. Copyright © 2016 Elsevier Ltd. All rights reserved.
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. © 2014 European Union.
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.
Freeze injury to southern pine seedlings
David B. South
2006-01-01
Freeze injury to roots and shoots of pines is affected by genotype and nursery practices. Local sources of shortleaf pine and Virginia pine that are grown in nurseries in USDA hardiness Zones 6 and 7a are relatively freeze tolerant. However, loblolly pine, slash pine, and longleaf pine seedlings have been injured by a number of freeze events (0 to 24 °F) in hardiness...
DOE Office of Scientific and Technical Information (OSTI.GOV)
Hancock, David, W.
2012-02-14
Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below freezing, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was freeze tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology formore » air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve freeze tolerance and mitigate freeze-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. Freeze tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack freeze tolerance. At this time, the most cost effective solutions are at the system level. The freeze mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.« less
The effect of undissolved air on isochoric freezing.
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. Copyright © 2016. Published by Elsevier Inc.
Persistent depressive disorder
... But, symptoms are not as severe as with major depression . Persistent depressive disorder used to be called dysthymia. ... with PDD will also have an episode of major depression at some point in their lives. Older people ...
Freeze-drying of lactic acid bacteria.
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.
Mazur, Peter
1963-01-01
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
Freeze-thaw durability of air-entrained concrete.
Shang, Huai-Shuai; Yi, Ting-Hua
2013-01-01
One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.
Coincidence probability as a measure of the average phase-space density at freeze-out
NASA Astrophysics Data System (ADS)
Bialas, A.; Czyz, W.; Zalewski, K.
2006-02-01
It is pointed out that the average semi-inclusive particle phase-space density at freeze-out can be determined from the coincidence probability of the events observed in multiparticle production. The method of measurement is described and its accuracy examined.
Teaching Process Engineering Principles Using an Ice Cream Maker
ERIC Educational Resources Information Center
Kaletunc, Gonul; Duemmel, Kevin; Gecik, Christopher
2007-01-01
The ice cream laboratory experiment is designed to illustrate and promote discussion of several engineering and science topics including material and energy balances, heat transfer, freezing, mass transfer, mixing, viscosity, and freezing point depression in a sophomore level engineering class. A pre-lab assignment requires the students to develop…
Tongdee, Pattama; Sukprasert, Matchuporn; Satirapod, Chonticha; Wongkularb, Anna; Choktanasiri, Wicham
2015-05-01
Cryopreservation of sperm is common methods to preserve male fertility. Sperm freezing, suggest slow programmable freezing caused lower change of sperm morphology than sperm freezing in vapor of liquid nitrogen. Ultra rapid freezing is easy to be worked on, less time, low cost and does not need high experience. To compare the effect on sperm motility, morphology and DNA integrity of post-thawed sperm after ultra rapid freezing and slow programmable freezing methods. Experimental study at laboratory of infertility unit, Department of Obstetrics and Gynecology, Faculty of Medicine Ramathibodi Hospital. Thirty-seven semen samples with normal semen analysis according to World Health Organization (WHO) 1999 [normal sperm volume ( 2 ml) and normal sperm concentration (≥ 20 x10(6)/ml) and sperm motility (≥ 50%)]. Semen samples were washed. Then each semen sample was divided into six cryovials. Two cryovials, 0.5 ml each, were cryopreserved by slow programmable freezing. Four 0.25 ml containing cryovials, were cryopreserved by ultra rapidfreezing method. After cryopreservationfor 1 month, thawedprocess was carried out at room temperature. Main outcomes are sperm motility was determined by Computer-Assisted Semen Analysis (CASA), sperm morphology was determined by eosin-methylene blue staining and sperm DNA integrity was assessed by TUNEL assay. Sperm motility was reduced significantly by both methods, from 70.4 (9.0)% to 29.1 (12.3)% in slowprogrammable freezing and to 19.7 (9.8)% in ultra rapid freezing (p < 0.05). Sperm motility decreased significantly more by ultra rapid freezing (p < 0.001). The percentage of normal sperm morphology and DNA integrity were also reduced significantly by both methods. However, no significant difference between the two methods was found (p > 0.05). Cryopreservation of human sperm for 1 month significantly decreased sperm motility, morphology and DNA integrity in both methods. However sperm motility was decreased more by ultra rapid
USDA-ARS?s Scientific Manuscript database
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...
[Point prevalence of depression in the Cracow population of 13 year old students in 1984 and 2001].
Modrzejewska, Renata; Bomba, Jacek
2006-01-01
Results of scarce epidemiological studies on depression in adolescents are diverse and dependent of survey methodology as well as on the theoretical approach of research. Those studies where the methods are comparable show that depression prevalence depends on the macrosocial situation and the adolescence stage. The study aimed to assess changes in depression prevalence in mid-adolescents between 1984 and 2001. A presumption was made that the social situation in Poland had changed in the last 17 years. In 2001 a representative sample of school attending 13 y.o. adolescents was screened with KID-IO "B1". The results were compared with those of a similar survey, using the same method, carried out in 1984. Point prevalence index in 2001 appeared to be lower than in the survey in 1984 (24.6% versus 31.6%). This resulted exclusively from a significant decrease in depression among girls (26.8% versus 42.2%). The obtained data allows for an interpretation of the findings as being a result of macrosocial changes. Other hypotheses e.g. influence of the adolescence timing and course requires a longitudinal prospective study.
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.
Tochigi, Mamoru; Usami, Satoshi; Matamura, Misato; Kitagawa, Yuko; Fukushima, Masako; Yonehara, Hiromi; Togo, Fumiharu; Nishida, Atsushi; Sasaki, Tsukasa
2016-01-01
To investigate the longitudinal relationship between sleep habits and mental health in adolescents. Multipoint observation data of up to five years were employed from a prospective cohort study of sleep habits and mental health status conducted from 2009 to 2013 in a unified junior and senior high school (grades 7-12) in Tokyo, Japan. A total of 1078 students answered a self-report questionnaire, including items on usual bed and wake-up times on school days, and the Japanese version of the 12-item General Health Questionnaire (GHQ-12). Latent growth model (LGM) analysis, which requires three or more time point data, showed that longitudinal changes in bedtime and GHQ-12 score (or score for depression/anxiety) were significantly and moderately correlated (correlation coefficient = 0.510, p < 0.05). Another result of interest was that, using an autoregressive cross-lagged (ARCL) model, bedtime and the depression/anxiety score had reciprocal effects the following year: ie, bedtime significantly affects the following year's depression/anxiety, and vice versa. In addition, the analysis provided estimates of mutually predicted changes: one-hour bedtime delay may worsen the GHQ-12 score by 0.2 points, and one-point worsening of the score may delay bedtime by 2.2 minutes. By using up to five multiple time point data, the present study confirms the correlational and reciprocally longitudinal relationship between bedtime delay and mental health status in Japanese adolescents. The results indicate that preventing late bedtime may have a significant effect on improving mental health in adolescents. Copyright © 2015 Elsevier B.V. All rights reserved.
NASA Technical Reports Server (NTRS)
Smith, Irwin D.; Dhooge, Patrick M.
1977-01-01
A series of tests was performed to ascertain the triple points of monomethylhydrazine and nitrogen tetroxide. A laboratory method indicated a triple point for monomethylhydrazine, but tests in a large vacuum chamber indicated that a triple point does not occur in spacelike conditions because the mono-methylhydrazine tends to supercool. Instead, an effective freezing point (with agitation) was obtained. New experimental values for liquid monomethylhydrazine vapor pressure were determined for temperatures from 275.2 to 207.6 K. The values were used to derive vapor pressure equations. Tentative values were obtained for the effective freezing point of nitrogen tetroxide spacelike conditions.
Freezing-induced deformation of biomaterials in cryomedicine
NASA Astrophysics Data System (ADS)
Ozcelikkale, Altug
Cryomedicine utilizes low temperature treatments of biological proteins, cells and tissues for cryopreservation, materials processing and cryotherapy. Lack of proper understanding of cryodamage that occurs during these applications remains to be the primary bottleneck for development of successful tissue cryopreservation and cryosurgery procedures. An engineering approach based on a view of biological systems as functional biomaterials can help identify, predict and control the primary cryodamage mechanisms by developing an understanding of underlying freezing-induced biophysical processes. In particular, freezing constitutes the main structural/mechanical origin of cryodamage and results in significant deformation of biomaterials at multiple length scales. Understanding of these freezing-induced deformation processes and their effects on post-thaw biomaterial functionality is currently lacking but will be critical to engineer improved cryomedicine procedures. This dissertation addresses this problem by presenting three separate but related studies of freezing-induced deformation at multiple length scales including nanometer-scale protein fibrils, single cells and whole tissues. A combination of rigorous experimentation and computational modeling is used to characterize post-thaw biomaterial structure and properties, predict biomaterial behavior and assess its post-thaw biological functionality. Firstly, freezing-induced damage on hierarchical extracellular matrix structure of collagen is investigated at molecular, fibril and matrix levels. Results indicate to a specific kind of fibril damage due to freezing-induced expansion of intrafibrillar fluid. This is followed by a study of freezing-induced cell and tissue deformation coupled to osmotically driven cellular water transport. Computational and semi empirical modeling of these processes indicate that intracellular deformation of the cell during freezing is heterogeneous and can interfere with cellular water
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).
Kawada, Tomoyuki; Yoshimura, Miwako
2012-04-01
To evaluate the relationship between the score of job satisfaction and depression. A total of 2737 workers (2198 men and 539 women) participated. A 100-point scale for evaluating job satisfaction and the Occupational Depression Scale were used. A logistic regression analysis was applied with adjustment for age. The mean age of the subjects was 42.2 years for men and 36.0 years for women. When the group with the highest job satisfaction score was set as the control, the odds ratios and 95% confidence intervals for depression in the groups with the lowest and second lowest scores were 16.3 (7.51 to 35.2) and 5.90 (2.70 to 12.9) in men and 8.02 (1.78 to 36.1) and 5.68 (1.26 to 25.7) in women, respectively. Job satisfaction was significantly associated with the depressive state, and causality should be clarified by a follow-up study.
The colligative properties of fruit juices by photopyroelectric calorimetry
NASA Astrophysics Data System (ADS)
Frandas, A.; Surducan, V.; Nagy, G.; Bicanic, D.
1999-03-01
The photopyroelectric method was used to study the depression of freezing point in juices prepared from selected apple and orange juice concentrates. By using the models for real solutions, the effective molecular weight of the dissolved solids was obtained. The acids concentration in the fruit juice is reflected both in the equivalent molecular weight (by lowering it) and in the interaction coefficients b and C. Using the data for the molecular weight and the characteristic coefficients, prediction curves for the samples investigated can be used in practice. Freezing point depression can also be used as an indicator of the degree of spoilage of fruit juices.
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
Kauppinen, Ari; Toiviainen, Maunu; Korhonen, Ossi; Aaltonen, Jaakko; Järvinen, Kristiina; Paaso, Janne; Juuti, Mikko; Ketolainen, Jarkko
2013-02-19
During the past decade, near-infrared (NIR) spectroscopy has been applied for in-line moisture content quantification during a freeze-drying process. However, NIR has been used as a single-vial technique and thus is not representative of the entire batch. This has been considered as one of the main barriers for NIR spectroscopy becoming widely used in process analytical technology (PAT) for freeze-drying. Clearly it would be essential to monitor samples that reliably represent the whole batch. The present study evaluated multipoint NIR spectroscopy for in-line moisture content quantification during a freeze-drying process. Aqueous sucrose solutions were used as model formulations. NIR data was calibrated to predict the moisture content using partial least-squares (PLS) regression with Karl Fischer titration being used as a reference method. PLS calibrations resulted in root-mean-square error of prediction (RMSEP) values lower than 0.13%. Three noncontact, diffuse reflectance NIR probe heads were positioned on the freeze-dryer shelf to measure the moisture content in a noninvasive manner, through the side of the glass vials. The results showed that the detection of unequal sublimation rates within a freeze-dryer shelf was possible with the multipoint NIR system in use. Furthermore, in-line moisture content quantification was reliable especially toward the end of the process. These findings indicate that the use of multipoint NIR spectroscopy can achieve representative quantification of moisture content and hence a drying end point determination to a desired residual moisture level.
Freeze-Thaw Durability of Air-Entrained Concrete
Shang, Huai-Shuai; Yi, Ting-Hua
2013-01-01
One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results. PMID:23576906
Bulk water freezing dynamics on superhydrophobic surfaces
NASA Astrophysics Data System (ADS)
Chavan, S.; Carpenter, J.; Nallapaneni, M.; Chen, J. Y.; Miljkovic, N.
2017-01-01
In this study, we elucidate the mechanisms governing the heat-transfer mediated, non-thermodynamic limited, freezing delay on non-wetting surfaces for a variety of characteristic length scales, Lc (volume/surface area, 3 mm < Lc < 6 mm) using carefully designed freezing experiments in a temperature-controlled, zero-humidity environment on thin water slabs. To probe the effect of surface wettability, we investigated the total time for room temperature water to completely freeze into ice on superhydrophilic ( θaapp→ 0°), hydrophilic (0° < θa < 90°), hydrophobic (90° < θa < 125°), and superhydrophobic ( θaapp→ 180°) surfaces. Our results show that at macroscopic length scales, heat conduction through the bulk water/ice layer dominates the freezing process when compared to heat conduction through the functional coatings or nanoscale gaps at the superhydrophobic substrate-water/ice interface. In order to verify our findings, and to determine when the surface structure thermal resistance approaches the water/ice resistance, we fabricated and tested the additional substrates coated with commercial superhydrophobic spray coatings, showing a monotonic increase in freezing time with coating thickness. The added thermal resistance of thicker coatings was much larger than that of the nanoscale superhydrophobic features, which reduced the droplet heat transfer and increased the total freezing time. Transient finite element method heat transfer simulations of the water slab freezing process were performed to calculate the overall heat transfer coefficient at the substrate-water/ice interface during freezing, and shown to be in the range of 1-2.5 kW/m2K for these experiments. The results shown here suggest that in order to exploit the heat-transfer mediated freezing delay, thicker superhydrophobic coatings must be deposited on the surface, where the coating resistance is comparable to the bulk water/ice conduction resistance.
A Theory of Immersion Freezing
NASA Technical Reports Server (NTRS)
Barahona, Donifan
2017-01-01
Immersion freezing is likely involved in the initiation of precipitation and determines to large extent the phase partitioning in convective clouds. Theoretical models commonly used to describe immersion freezing in atmospheric models are based on the classical nucleation theory which however neglects important interactions near the immersed particle that may affect nucleation rates. This work introduces a new theory of immersion freezing based on two premises. First, immersion ice nucleation is mediated by the modification of the properties of water near the particle-liquid interface, rather than by the geometry of the ice germ. Second, the same mechanism that leads to the decrease in the work of germ formation also decreases the mobility of water molecules near the immersed particle. These two premises allow establishing general thermodynamic constraints to the ice nucleation rate. Analysis of the new theory shows that active sites likely trigger ice nucleation, but they do not control the overall nucleation rate nor the probability of freezing. It also suggests that materials with different ice nucleation efficiency may exhibit similar freezing temperatures under similar conditions but differ in their sensitivity to particle surface area and cooling rate. Predicted nucleation rates show good agreement with observations for a diverse set of materials including dust, black carbon and bacterial ice nucleating particles. The application of the new theory within the NASA Global Earth System Model (GEOS-5) is also discussed.
USDA-ARS?s Scientific Manuscript database
Use of glycerin and calcium chloride to reduce the freezing point and improve quality of bulk stored fermented cucumbers brined without NaCl, was explored. The incidence of pre-freezing injury on the fruits, caused by deposition in tanks containing cushion brine prepared with 2.5% calcium chloride, ...
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.
Land cover controls on depression-focused recharge: an example from southern Ontario
NASA Astrophysics Data System (ADS)
Buttle, J. M.; Greenwood, W. J.
2015-12-01
The Oak Ridges Moraine (ORM) is a critical hydrogeologic feature in southern Ontario. Although previous research has highlighted the implications of spatially-focused recharge in closed topographic depressions for regional groundwater resources, such depression-focused recharge (DFR) has not been empirically demonstrated on the ORM. Permeable surficial sands and gravels mantling much of the ORM imply that water fluxes will largely be vertical recharge rather than lateral downslope transfer into depressions. Nevertheless, lateral fluxes may occur in winter and spring, when concrete frost development encourages surface runoff of rainfall and snowmelt. The potential for DFR was examined under forest and agricultural land cover with similar soils and surficial geology. Soil water contents, soil temperatures and ground frost thickness were measured at the crest and base of closed depressions in two agricultural fields and two forest stands on permeable ORM outcrops. Recharge from late-fall to the end of spring snowmelt was estimated via 1-d water balances and surface-applied bromide tracing. Both forest and agricultural sites experienced soil freezing; however, greater soil water contents prior to freeze-up at the latter led to concrete soil frost development. This resulted in lateral movement of snowmelt and rainfall into topographic depressions and surface ponding, which did not occur in forest depressions. Water balance recharge exceeded estimates from the bromide tracer approach at all locations; nevertheless, both methods indicated DRF exceeded recharge at the depression crest in agricultural areas with little difference in forest areas. Water balance estimates suggest winter-spring DFR (1300 - 2000 mm) is 3-5× recharge on level agricultural sites. Differences in the potential for DFR between agricultural and forest land covers have important implications for the spatial variability of recharge fluxes and the quality of recharging water on the ORM.
Rapid freezing without cooling equilibration in canine sperm.
Kim, Suhee; Lee, Yongcheol; Yang, Honghyun; Kim, Yong-Jun
2012-01-01
The aim of this study was to develop a rapid method of canine semen freezing without cooling equilibration using treatment with different cryoprotectant agents (CPAs) and freezing in liquid nitrogen (LN(2)) vapor in a 0.5-mL straw via modifying vitrification. Ejaculates from eight beagle dogs were frozen with different CPAs (CPA-free, 5% glycerol, 5% ethylene glycol, and 10% ethylene glycol) and freezing times (direct plunging into LN(2) or freezing for 1, 2, 3, or 10 min in LN(2) vapor before plunging into LN(2)). Frozen-thawed sperm were evaluated for motility, viability, normal morphology, and plasma- and acrosome-membrane integrities. The 5% glycerol treatment resulted in improved sperm motility, plasma-membrane integrity and acrosome-membrane integrity (P<0.05). Freezing in LN(2) vapor showed improved sperm motility, viability, and plasma membrane integrity (P<0.05), and freezing for more than 2 min in LN(2) vapor increased acrosome-membrane integrity compared with direct plunging into LN(2) (P<0.05). The direct plunging into LN(2) showed no motile sperm. However, freezing for more than 2 min in LN(2) vapor increased the total abnormalities compared to direct plunging into LN(2) (P<0.05). In conclusion, use of 5% glycerol and freezing in LN(2) vapor were essential for the rapid freezing of canine sperm without cooling equilibration. In particular, holding for 2 min in LN(2) vapor was sufficient to yield successful rapid freezing. This rapid freezing method is simple and effective in canine sperm and would be helpful to offer information for trial of vitrification in large volumes of canine sperm. Copyright © 2012 Elsevier B.V. All rights reserved.
9 CFR 590.536 - Freezing operations.
Code of Federal Regulations, 2012 CFR
2012-01-01
..., 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 egg...
9 CFR 590.536 - Freezing operations.
Code of Federal Regulations, 2014 CFR
2014-01-01
..., 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 egg...
9 CFR 590.536 - Freezing operations.
Code of Federal Regulations, 2011 CFR
2011-01-01
..., 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 egg...
9 CFR 590.536 - Freezing operations.
Code of Federal Regulations, 2013 CFR
2013-01-01
..., 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 egg...
DOE Office of Scientific and Technical Information (OSTI.GOV)
Blennow, Mattias; Fernandez-Martínez, Enrique; Zaldívar, Bryan, E-mail: emb@kth.se, E-mail: enrique.fernandez-martinez@uam.es, E-mail: b.zaldivar.m@csic.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 analyticalmore » 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.« less
Jehu, Deborah A; Cantù, Hiram; Hill, Allen; Paquette, Caroline; Côté, Julie N; Nantel, Julie
2018-01-01
We aimed to determine the effects of levodopa medication on the performance of a repetitive pointing task while standing, and to investigate the optimal trial duration in individuals with Parkinson's disease, and older adults. Seventeen individuals with Parkinson's disease (5 freezers) and 9 older adults stood on force platforms for 30 s and 120 s while performing a bilateral repetitive pointing task, tracked by motion capture. Participants with Parkinson's disease were assessed on and off medication and older adults were also assessed on separate days. The main findings were that: 1) on medication, participants with Parkinson's exhibited greater center of pressure root mean square in the medial-lateral direction, greater velocity in the medial-lateral and anterior-posterior directions, and greater range in the medial-lateral direction than off medication; 2) longer trial durations resulted in greater center of pressure range in the medial-lateral and anterior-posterior directions and greater coefficient of variation in finger pointing on the least affected side; 3) Parkinson's participants exhibited larger range in the medial-lateral direction compared to older adults; 4) off medication, freezers presented with less range and root mean square in the anterior-posterior direction than non-freezers; and 5) a correlation emerged between the freezing of gait questionnaire and pointing asymmetry and the coefficient of variation of pointing on the most affected side. Therefore, Parkinson's medication may increase instability during a repetitive pointing task. Longer trials may provide a better depiction of sway by discriminating between those with and without neurological impairment. Individuals with Parkinson's were less stable than older adults, supporting that they are at a greater risk for falls. The greater restrictive postural strategy in freezers compared to non-freezers is likely a factor that augments fall-risk. Lastly, the link between freezing of gait and
Freezing tolerance of conifer seeds and germinants.
Hawkins, B J; Guest, H J; Kolotelo, D
2003-12-01
Survival after freezing was measured for seeds and germinants of four seedlots each of interior spruce (Picea glauca x engelmannii complex), lodgepole pine (Pinus contorta Dougl. ex Loud.), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and western red cedar (Thuja plicata Donn ex D. Donn). Effects of eight seed treatments on post-freezing survival of seeds and germinants were tested: dry, imbibed and stratified seed, and seed placed in a growth chamber for 2, 5, 10, 15, 20 or 30 days in a 16-h photoperiod and a 22/17 degrees C thermoperiod. Survival was related to the water content of seeds and germinants, germination rate and seedlot origin. After freezing for 3 h at -196 degrees C, dry seed of most seedlots of interior spruce, Douglas-fir and western red cedar had 84-96% germination, whereas lodgepole pine seedlots had 53-82% germination. Freezing tolerance declined significantly after imbibition in lodgepole pine, Douglas-fir and interior spruce seed (western red cedar was not tested), and mean LT50 of imbibed seed of these species was -30, -24.5 and -20 degrees C, respectively. Freezing tolerance continued to decline to a minimum LT50 of -4 to -7 degrees C after 10 days in a growth chamber for interior spruce, Douglas-fir and lodgepole pine, or after 15 days for western red cedar. Minimum freezing tolerance was reached at the stage of rapid hypocotyl elongation. In all species, a slight increase in freezing tolerance of germinants was observed once cotyledons emerged from the seed coat. The decrease in freezing tolerance during the transition from dry to germinating seed correlated with increases in seed water content. Changes in freezing tolerance between 10 and 30 days in the growth chamber were not correlated with seedling water content. Within a species, seedlots differed significantly in freezing tolerance after 2 or 5 days in the growth chamber. Because all seedlots of interior spruce and lodgepole pine germinated quickly, there was no correlation
RÄISÄNEN, MIKKO; REPO, TAPANI; LEHTO, TARJA
2006-01-01
• Background Effects of cooling rates on bud frost hardiness have been studied but there is little information on bud responses to thawing. Since the cell wall pore size has been found to increase with boron (B) deficiency, B deficiency may affect the supercooling ability of buds in winter. • Methods The effects of duration of thawing time and rate of cooling on bud frost hardiness of Norway spruce (Picea abies) were studied in a B fertilization trial in February 2003 and March 2005. Frost hardiness of apical buds was determined by differential thermal analysis (DTA) and visual scoring of damage. • Key Results In 2003, the freezing point of primordial shoots of buds (Tf), i.e. the low-temperature exotherm (LTE), was, on average, −39 °C when buds were thawed for less than 3 h and the Tf increased to −21 °C after 18 h of thawing. During the first 4 h of thawing, the rate of dehardening was 6 °C h−1. In 2005, buds dehardened linearly from −39 °C to −35 °C at a rate of 0·7 °C h−1. In 2003, different cooling rates of 1–5 °C h−1 had a minor effect on Tf but in 2005 with slow cooling rates Tf decreased. In both samplings, at cooling rates of 2 and 1 °C h−1, Tf was slightly higher in B-fertilized than in non-fertilized trees. By contrast, at very short thawing times in 2003, Tf was somewhat lower in B-fertilized trees. • Conclusions There was little evidence of reduced frost hardiness in trees with low B status. This study showed that buds deharden rapidly when exposed to above-freezing temperatures in winter, but if cooled again they reharden more slowly. According to this study, rapid dehardening of buds has to be taken into account in assessments of frost hardiness. PMID:16464880
USDA-ARS?s Scientific Manuscript database
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...
O’Connor, Erin E.; Langer, David A.; Tompson, Martha C.
2017-01-01
Maternal depression is a well-documented risk factor for youth depression, and taking into account its severity and chronicity may provide important insight into the degree of risk conferred. This study explored the degree to which the severity/chronicity of maternal depression history explained variance in youth internalizing and externalizing symptoms above and beyond current maternal depressive symptoms among 171 youth (58% male) ages 8 to 12 over a span of three years. Severity and chronicity of past maternal depression and current maternal depressive symptoms were examined as predictors of parent-reported youth internalizing and externalizing symptomatology, as well as youth self-reported depressive symptoms. Severity and chronicity of past maternal depression did not account for additional variance in youth internalizing and externalizing symptoms at Time 1 beyond what was accounted for by maternal depressive symptoms at Time 1. Longitudinal growth curve modeling indicated that prior severity/chronicity of maternal depression predicted levels of youth internalizing and externalizing symptoms at each time point when controlling for current maternal depressive symptoms at each time point. Chronicity of maternal depression, apart from severity, also predicted rate of change in youth externalizing symptoms over time. These findings highlight the importance of screening and assessing for current maternal depressive symptoms, as well as the nature of past depressive episodes. Possible mechanisms underlying the association between severity/chronicity of maternal depression and youth outcomes, such as residual effects from depressive history on mother–child interactions, are discussed. PMID:27401880
The prevalence of depression and the accuracy of depression screening tools in migraine patients.
Amoozegar, Farnaz; Patten, Scott B; Becker, Werner J; Bulloch, Andrew G M; Fiest, Kirsten M; Davenport, W Jeptha; Carroll, Christopher R; Jette, Nathalie
2017-09-01
Migraine and depression are common comorbid conditions. The purpose of this study was to assess how well the Patient Health Questionnaire (PHQ-9) and the Hospital Anxiety and Depression Scale (HADS) perform as depression screening tools in patients with migraine. Three hundred consecutive migraine patients were recruited from a large headache center. The PHQ-9 and HADS were self-administered and validated against the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV, a gold standard for the diagnosis of depression. Sensitivity, specificity, positive predictive value, negative predictive value and receiver-operator characteristic curves were calculated for the PHQ-9 and HADS. At the traditional cut-point of 10, the PHQ-9 demonstrated 82.0% sensitivity and 79.9% specificity. At a cut-point of 8, the HADS demonstrated 86.5% sensitivity and specificity. The PHQ-9 algorithm performed poorly (53.8% sensitivity, 94.9% specificity). The point prevalence of depression in this study was 25.0% (95% CI 19.0-31.0), and 17.0% of patients had untreated depression. In this study, the PHQ-9 and HADS performed well in migraine patients attending a headache clinic, but optimal cut-points to screen for depression vary depending on the goals of the assessment. Also, migraine patients attending a headache clinic have a high prevalence of depression and many are inadequately treated. Future studies are needed to confirm these findings and to evaluate the impact of depression screening. Copyright © 2017 Elsevier Inc. All rights reserved.
Mangum, B W
1983-07-01
In an investigation of the melting and freezing behavior of succinonitrile, the triple-point temperature was determined to be 58.0805 degrees C, with an estimated uncertainty of +/- 0.0015 degrees C relative to the International Practical Temperature Scale of 1968 (IPTS-68). The triple-point temperature of this material is evaluated as a temperature-fixed point, and some clinical laboratory applications of this fixed point are proposed. In conjunction with the gallium and ice points, the availability of succinonitrile permits thermistor thermometers to be calibrated accurately and easily on the IPTS-68.
NASA Astrophysics Data System (ADS)
Pokhodun, A. I.
2010-01-01
In the framework of the CIPM MRA, a first COOMET comparison "Comparison of the ITS-90 realizations in the range from 0.01 °C to 429.7485 °C (from the triple point of water to the freezing point of zinc)", registered in the KCDB under the identifier "COOMET.T-K3", was carried out in 2005-2007. Four national metrology institutes took part in this comparison: VNIIM (Russian Federation), SMU (Slovakia), BelGIM (Republic of Belarus) and NSC IM (Ukraine), and two of them (VNIIM and SMU) ensured the linkage with key comparisons CCT-K3 and CCT-K4, in order to disseminate the metrological equivalence to the measurement standards of NSC IM and BelGIM. NSC IM, however, had to withdraw its results, and at the meeting of Technical Committee T-10 of COOMET it was decided to carry out a supplementary bilateral comparison between VNIIM and the NSC IM for realization of the ITS-90 in the same range of temperature. This was registered in the KCDB under the identifier COOMET.T-S1 and measurements were performed in 2008-2009. From the results presented in this report, it is possible to draw the conclusion that the COOMET supplementary comparison COOMET.T-S1 demonstrates the CMC uncertainties claimed by the NSC IM for the melting point of gallium 0.236 mK (k = 2), and the freezing points of indium 1.040 mK (k = 2), tin 0.858 mK (k = 2) and zinc 0.944 mK (k = 2). In September 2012 the Working Group on key Comparisons (WG 7) of the CCT upgraded this comparison to a COOMET key comparison of the 'CCT-K3' type. It is now identified as COOMET.T-K3.1. In April 2013 this report was superseded by item 03006 in the Technical Supplement of 2013. 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).
Thermodynamics of freezing and melting
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
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. Copyright © 2013 Elsevier Inc. All rights reserved.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Sun, Kai; Li, Ruixin; Jiang, Wenxue, E-mail: jiangortholivea@sina.cn
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 thanmore » 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. - Highlights: • Silk fibroin/collagen was fabricated using 3D printing. • Physical characterization and Cell compatibility were compared. • 3D printed scaffold exhibited better overall performance.« less
Nock, Charles A; Lecigne, Bastien; Taugourdeau, Olivier; Greene, David F; Dauzat, Jean; Delagrange, Sylvain; Messier, Christian
2016-06-01
Despite a longstanding interest in variation in tree species vulnerability to ice storm damage, quantitative analyses of the influence of crown structure on within-crown variation in ice accretion are rare. In particular, the effect of prior interception by higher branches on lower branch accumulation remains unstudied. The aim of this study was to test the hypothesis that intra-crown ice accretion can be predicted by a measure of the degree of sheltering by neighbouring branches. Freezing rain was artificially applied to Acer platanoides L., and in situ branch-ice thickness was measured directly and from LiDAR point clouds. Two models of freezing rain interception were developed: 'IceCube', which uses point clouds to relate ice accretion to a voxel-based index (sheltering factor; SF) of the sheltering effect of branch elements above a measurement point; and 'IceTree', a simulation model for in silico evaluation of the interception pattern of freezing rain in virtual tree crowns. Intra-crown radial ice accretion varied strongly, declining from the tips to the bases of branches and from the top to the base of the crown. SF for branches varied strongly within the crown, and differences among branches were consistent for a range of model parameters. Intra-crown variation in ice accretion on branches was related to SF (R(2) = 0·46), with in silico results from IceTree supporting empirical relationships from IceCube. Empirical results and simulations confirmed a key role for crown architecture in determining intra-crown patterns of ice accretion. As suspected, the concentration of freezing rain droplets is attenuated by passage through the upper crown, and thus higher branches accumulate more ice than lower branches. This is the first step in developing a model that can provide a quantitative basis for investigating intra-crown and inter-specific variation in freezing rain damage. © The Author 2016. Published by Oxford University Press on behalf of the Annals of
Nock, Charles A.; Lecigne, Bastien; Taugourdeau, Olivier; Greene, David F.; Dauzat, Jean; Delagrange, Sylvain; Messier, Christian
2016-01-01
Background and Aims Despite a longstanding interest in variation in tree species vulnerability to ice storm damage, quantitative analyses of the influence of crown structure on within-crown variation in ice accretion are rare. In particular, the effect of prior interception by higher branches on lower branch accumulation remains unstudied. The aim of this study was to test the hypothesis that intra-crown ice accretion can be predicted by a measure of the degree of sheltering by neighbouring branches. Methods Freezing rain was artificially applied to Acer platanoides L., and in situ branch-ice thickness was measured directly and from LiDAR point clouds. Two models of freezing rain interception were developed: ‘IceCube’, which uses point clouds to relate ice accretion to a voxel-based index (sheltering factor; SF) of the sheltering effect of branch elements above a measurement point; and ‘IceTree’, a simulation model for in silico evaluation of the interception pattern of freezing rain in virtual tree crowns. Key Results Intra-crown radial ice accretion varied strongly, declining from the tips to the bases of branches and from the top to the base of the crown. SF for branches varied strongly within the crown, and differences among branches were consistent for a range of model parameters. Intra-crown variation in ice accretion on branches was related to SF (R2 = 0·46), with in silico results from IceTree supporting empirical relationships from IceCube. Conclusions Empirical results and simulations confirmed a key role for crown architecture in determining intra-crown patterns of ice accretion. As suspected, the concentration of freezing rain droplets is attenuated by passage through the upper crown, and thus higher branches accumulate more ice than lower branches. This is the first step in developing a model that can provide a quantitative basis for investigating intra-crown and inter-specific variation in freezing rain damage. PMID:27107412
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.
Ultrastructure of sea urchin calcified tissues after high-pressure freezing and freeze substitution.
Ameye, L; Hermann, R; Dubois, P
2000-08-01
The improvements brought by high-pressure freezing/freeze substitution fixation methods to the ultrastructural preservation of echinoderm mineralized tissues are investigated in developing pedicellariae and teeth of the echinoid Paracentrotus lividus. Three freeze substitution (FS) protocols were tested: one in the presence of osmium tetroxide, one in the presence of uranyl acetate, and the last in the presence of gallic acid. FS in the presence of osmium tetroxide significantly improved cell ultrastructure preservation and should especially be used for ultrastructural studies involving vesicles and the Golgi apparatus. With all protocols, multivesicular bodies, suggested to contain Ca(2+), were evident for the first time in skeleton-forming cells. FS in the presence of gallic acid allowed us to confirm the structured and insoluble character of a part of the organic matrix of mineralization in the calcification sites of the tooth, an observation which modifies the current understanding of biomineralization control in echinoderms. Copyright 2000 Academic Press.
Optimum Parameters for Freeze-Drying Decellularized Arterial Scaffolds
Sheridan, William S.; Duffy, Garry P.
2013-01-01
Decellularized arterial scaffolds have achieved success in advancing toward clinical use as vascular grafts. However, concerns remain regarding long-term preservation and sterilization of these scaffolds. Freeze drying offers a means of overcoming these concerns. In this study, we investigated the effects of various freeze-drying protocols on decellularized porcine carotid arteries and consequently, determined the optimum parameters to fabricate a stable, preserved scaffold with unaltered mechanical properties. Freeze drying by constant slow cooling to two final temperatures ((Tf), −10°C and −40°C) versus instant freezing was investigated by histological examination and mechanical testing. Slow cooling to Tf= −10°C produced a stiffer and less distensible response than the non freeze-dried scaffolds and resulted in disruption to the collagen fibers. The mechanical response of Tf= −40°C scaffolds demonstrated disruption to the elastin network, which was confirmed with histology. Snap freezing scaffolds in liquid nitrogen and freeze drying to Tf= −40°C with a precooled shelf at −60°C produced scaffolds with unaltered mechanical properties and a histology resembling non-freeze-dried scaffolds. The results of this study demonstrate the importance of optimizing the nucleation and ice crystal growth/size to ensure homogenous drying, preventing extracellular matrix disruption and subsequent inferior mechanical properties. This new manufacturing protocol creates the means for the preservation and sterilization of decellularized arterial scaffolds while simultaneously maintaining the mechanical properties of the tissue. PMID:23614758
Jang, Seok-Joon; Rokugo, Keitetsu; Park, Wan-Shin; Yun, Hyun-Do
2014-01-01
This paper provides experimental results to investigate the mechanical properties of sustainable strain-hardening cement composite (2SHCC) for infrastructures after freeze-thaw actions. To improve the sustainability of SHCC materials in this study, high energy-consumptive components—silica sand, cement, and polyvinyl alcohol (PVA) fibers—in the conventional SHCC materials are partially replaced with recycled materials such as recycled sand, fly ash, and polyethylene terephthalate (PET) fibers, respectively. To investigate the mechanical properties of green SHCC that contains recycled materials, the cement, PVA fiber and silica sand were replaced with 10% fly ash, 25% PET fiber, and 10% recycled aggregate based on preliminary experimental results for the development of 2SHCC material, respectively. The dynamic modulus of elasticity and weight for 2SHCC material were measured at every 30 cycles of freeze-thaw. The effects of freeze-thaw cycles on the mechanical properties of sustainable SHCC are evaluated by conducting compressive tests, four-point flexural tests, direct tensile tests and prism splitting tests after 90, 180, and 300 cycles of rapid freeze-thaw. Freeze-thaw testing was conducted according to ASTM C 666 Procedure A. Test results show that after 300 cycles of freezing and thawing actions, the dynamic modulus of elasticity and mass loss of damaged 2SHCC were similar to those of virgin 2SHCC, while the freeze-thaw cycles influence mechanical properties of the 2SHCC material except for compressive behavior. PMID:28788522
Dêbska, Ewa; Janas, Adam; Bañczyk, Wojciech; Janas-Kozik, Małgorzata
2011-09-01
The target of this work is to consider if depressive symptoms intercurrent with patients suffering from Anorexia Nervosa (AN) and Bulimia Nervosa (BN) form a depression complex or whether they are physiological depression accompanying adolescence. We wished to observe the perception of these patients,of their functioning, both social and within their families and also looking for common point in the issues mentioned above trying to locate them within the course of the basic illness. We studied 19 patients suffering from eating disorders, and aged between 12 and 24 years old. 15 of them suffered from the restrictive form of AN and 4 suffered from BN. The control group consisted of 30 healthy girls in the same age interval. In the study authors used the Beck Depression Inventory (BDI) and the Quebec Quality of Life Questionnaire. Comparison of a number of points acquired in the survey using Beck Depression Scale revealed statistic significance at the level p<0.001 which points to a more frequent occurrence of depression symptoms among persons with eating disorders comparing to control group. The survey using the Questionnaire for Social Quality showed no statistically significant differences between study and control groups (p>0.05). The authors observed a statistically significant increased frequency of suicidal thoughts in the study group compared to the controls. To diagnose depression, depressive symptoms presented by the patients must give the image of depression at the clinical level. The result of the Beck's scale needs to be confronted with the clinical picture. Depression in adolescence requires differentiation from depressiveness.
7 CFR 58.620 - Freezing and packaging rooms.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 3 2013-01-01 2013-01-01 false Freezing and packaging rooms. 58.620 Section 58.620... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall be...
7 CFR 58.620 - Freezing and packaging rooms.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 3 2014-01-01 2014-01-01 false Freezing and packaging rooms. 58.620 Section 58.620... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall be...
7 CFR 58.620 - Freezing and packaging rooms.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 3 2012-01-01 2012-01-01 false Freezing and packaging rooms. 58.620 Section 58.620... Specifications for Dairy Plants Approved for USDA Inspection and Grading Service 1 Rooms and Compartments § 58.620 Freezing and packaging rooms. The rooms used for freezing and packaging frozen desserts shall be...
7 CFR 305.18 - Quick freeze treatment schedule.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 5 2010-01-01 2010-01-01 false Quick freeze treatment schedule. 305.18 Section 305.18... SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS Quick Freeze Treatments § 305.18 Quick freeze treatment schedule. (a) T110. (1) Initially, lower the commodity's temperature to 0 °F or below. (2) Hold...
References on Compression of Freeze-Dried Foods
1978-08-01
ready-to-eat, freeze-dried scrambled egg . Swift and Co., Contract No. DA 19- 129-AMC-121. 67-49-FD (FD-54). January 1967 (AD 650637). In the design...significantly poorer in organoleptic properties than from grades A and B eggs. Freeze- dried scrambled egg packed in cans kept better in storage than when...scrambled, cooked, freeze-dried whole egg product was developed which possessed the appearance, aroma, flavor and texture similar to pan- fried scrambled
Ambros, S; Hofer, F; Kulozik, U
2018-05-31
Microwave freeze drying in comparison to conventional freeze drying allows for intensification of the preservation process of lactic acid bacteria without imposing additional processing stress. Viability as a function of storage time of microwave freeze-dried Lactobacillus paracasei ssp. paracasei F19 was investigated in comparison to conventionally lyophilized bacteria of the same strain. Further, the impact of the protectants, sorbitol, trehalose and maltodextrin, on shelf life was analyzed. The highest inactivation rates of 0.035 and 0.045 d -1 , respectively, were found for cultures without protectants. Thus, all additives were found to exhibit a protective effect during storage with inactivation rates between 0.015 and 0.040 d -1 . Although trehalose and maltodextrin samples were in the glassy state during storage, in contrast to samples containing sorbitol as protectant, the best protective effect could be found for sorbitol with the lowest inactivation rate of 0.015 d -1 . Due to its low molecular weight, it might protect cells owing to better adsorption to the cytoplasma membrane. Sorbitol additionally shows antioxidative properties. Storage behavior of microwave freeze-dried cultures follows the typical behavior of a product dried by conventional lyophilization. No significant influence of the drying technique on storage behavior was detected. General findings concerning storage behavior in freeze drying are likely to be applicable in microwave freeze drying with only slight adjustments. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Recent developments in smart freezing technology applied to fresh foods.
Xu, Ji-Cheng; Zhang, Min; Mujumdar, Arun S; Adhikari, Benu
2017-09-02
Due to the increased awareness of consumers in sensorial and nutritional quality of frozen foods, the freezing technology has to seek new and innovative technologies for better retaining the fresh like quality of foods. In this article, we review the recent developments in smart freezing technology applied to fresh foods. The application of these intelligent technologies and the associated underpinning concepts have greatly improved the quality of frozen foods and the freezing efficiency. These technologies are able to automatically collect the information in-line during freezing and help control the freezing process better. Smart freezing technology includes new and intelligent technologies and concepts applied to the pretreatment of the frozen product, freezing processes, cold chain logistics as well as warehouse management. These technologies enable real-time monitoring of quality during the freezing process and help improve product quality and freezing efficiency. We also provide a brief overview of several sensing technologies used to achieve automatic control of individual steps of freezing process. These sensing technologies include computer vision, electronic nose, electronic tongue, digital simulation, confocal laser, near infrared spectroscopy, nuclear magnetic resonance technology and ultrasound. Understanding of the mechanism of these new technologies will be helpful for applying them to improve the quality of frozen foods.
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
Freeze-drying of yeast cultures.
Bond, Chris
2007-01-01
A method is described that allows yeast species to be stored using a variation on the standard freeze-drying method, which employs evaporative cooling in a two-stage process. Yeast cultures are placed in glass ampoules after having been mixed with a lyoprotectant. Primary drying is carried out using a centrifuge head connected to a standard freeze-dryer. Once the centrifuge head is running, air is removed and evaporated liquid is captured in the freeze-dryer. Centrifugation continues for 15 min and primary drying for a further 3 h. The ampoules are constricted using a glass blowing torch. They are then placed on the freeze-dryer manifold for secondary drying under vacuum overnight, using phosphorus pentoxide as a desiccant. The ampoules are sealed and removed from the manifold by melting the constricted section. Although the process causes an initial large drop in viability, further losses after storage are minimal. Yeast strains have remained viable for more than 30 yr when stored using this method and sufficient cells are recovered to produce new working stocks. Although survival rates are strain specific, nearly all National Collection of Yeast Cultures strains covering most yeast genera, have been successfully stored with little or no detectable change in strain characteristics.
Freeze-all cycle for all normal responders?
Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo
2017-02-01
The purpose of this study is to evaluate the freeze-all strategy in subgroups of normal responders, to assess whether this strategy is beneficial regardless of ovarian response, and to evaluate the possibility of implementing an individualized embryo transfer (iET) based on ovarian response. This was an observational, cohort study performed in a private IVF center. A total of 938 IVF cycles were included in this study. The patients were submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone (GnRH) antagonist protocol and a cleavage-stage day 3 embryo transfer. We performed a comparison of outcomes between the fresh embryo transfer (n = 523) and the freeze-all cycles (n = 415). The analysis was performed in two subgroups of patients based on the number of retrieved oocytes: Group 1 (4-9 oocytes) and Group 2 (10-15 oocytes). In Group 1 (4-9 retrieved oocytes), the implantation rates (IR) were 17.9 and 20.5% (P = 0.259) in the fresh and freeze-all group, respectively; the ongoing pregnancy rates (OPR) were 31 and 33% (P = 0.577) in the fresh and freeze-all group, respectively. In Group 2 (10-15 oocytes), the IR were 22.1 and 30.1% (P = 0.028) and the OPR were 34 and 47% (P = 0.021) in the fresh and freeze-all groups, respectively. Although the freeze-all policy may be related to better in vitro fertilization (IVF) outcomes in normal responders, these potential advantages decrease with worsening ovarian response. Patients with poorer ovarian response do not benefit from the freeze-all strategy.
Woolfson, A David; Umrethia, Manish L; Kett, Victoria L; Malcolm, R Karl
2010-03-30
Dapivirine mucoadhesive gels and freeze-dried tablets were prepared using a 3x3x2 factorial design. An artificial neural network (ANN) with multi-layer perception was used to investigate the effect of hydroxypropyl-methylcellulose (HPMC): polyvinylpyrrolidone (PVP) ratio (X1), mucoadhesive concentration (X2) and delivery system (gel or freeze-dried mucoadhesive tablet, X3) on response variables; cumulative release of dapivirine at 24h (Q(24)), mucoadhesive force (F(max)) and zero-rate viscosity. Optimisation was performed by minimising the error between the experimental and predicted values of responses by ANN. The method was validated using check point analysis by preparing six formulations of gels and their corresponding freeze-dried tablets randomly selected from within the design space of contour plots. Experimental and predicted values of response variables were not significantly different (p>0.05, two-sided paired t-test). For gels, Q(24) values were higher than their corresponding freeze-dried tablets. F(max) values for freeze-dried tablets were significantly different (2-4 times greater, p>0.05, two-sided paired t-test) compared to equivalent gels. Freeze-dried tablets having lower values for X1 and higher values for X2 components offered the best compromise between effective dapivirine release, mucoadhesion and viscosity such that increased vaginal residence time was likely to be achieved. Copyright (c) 2009 Elsevier B.V. All rights reserved.
Response of seasonal soil freeze depth to climate change across China
NASA Astrophysics Data System (ADS)
Peng, Xiaoqing; Zhang, Tingjun; Frauenfeld, Oliver W.; Wang, Kang; Cao, Bin; Zhong, Xinyue; Su, Hang; Mu, Cuicui
2017-05-01
The response of seasonal soil freeze depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil freeze depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil freeze depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil freeze depth decreased significantly at a rate of -0.18 ± 0.03 cm yr-1, resulting in a net decrease of 8.05 ± 1.5 cm over 1967-2012 across China. On the regional scale, soil freeze depth decreases varied between 0.0 and 0.4 cm yr-1 in most parts of China during 1950-2009. By investigating potential climatic and environmental driving factors of soil freeze depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil freeze depth. Changes in snow depth are not correlated with soil freeze depth. Air and ground surface freezing indices are positively correlated with soil freeze depth. Comparing these potential driving factors of soil freeze depth, we find that freezing index and vegetation growth are more strongly correlated with soil freeze depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal freeze depth. These results are important for understanding the soil freeze-thaw dynamics and the impacts of soil freeze depth on ecosystem and hydrological process.
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.
Singh, Gurdev; Soundarapandian, S
2018-03-01
The long standing need of the implant manufacturing industries is to fabricate multi-matrix, customized porous scaffold as cost-effectively. In recent years, freeze casting has shown greater opportunity in the fabrication of porous scaffolds (tricalcium phosphate, hydroxyapatite, bioglass, alumina, etc.) such as at ease and good control over pore size, porosity, a range of materials and economic feasibility. In particular, tricalcium phosphate (TCP) has proved as it possesses good biocompatible (osteoinduction, osteoconduction, etc.) and biodegradability hence beta-tricalcium phosphate (β-TCP, particle size of 10µm) was used as base material and camphene was used as a freezing vehicle in this study. Both freezing conditions such as constant freezing temperature (CFT) and constant freezing rate (CFR) were used for six different conditional samples (CFT: 30, 35 and 40vol% solid loading; similarly CFR: 30, 35 and 40vol% solid loading) to study and understand the effect of various properties (pore size, porosity and compressive strength) of the freeze-cast porous scaffold. It was observed that the average size of the pore was varying linearly as from lower to higher when the solid loading was varying higher to lower. With the help of scanning electron micrographs (SEM), it was observed that the average size of pore during CFR (9.7/ 6.5/ 4.9µm) was comparatively higher than the process of CFT (6.0/ 4.8/ 2.6µm) with respect to the same solid loading (30/ 35/ 40vol%) conditions. From the Gas pycnometer analysis, it was found that the porosity in both freezing conditions (CFT, CFR) were almost near values such as 32.8% and 28.5%. Further to be observed that with the increase in solid loading, the total porosity value has decreased due to the reduction in the concentration of the freezing vehicle. Hence, the freezing vehicle was found as responsible for the formation of appropriate size and orientation of pores during freeze casting. The compressive strength (CS
[Point prevalence of depression in the Kraków population of 10 year old children in 1984 and 2001].
Modrzejewska, Renata; Bomba, Jacek
2006-01-01
Results of scarce epidemiological studies on depression in children are diverse and dependent of survey methodology as well as on the theoretical approach of the research. Those studies where the methods are comparable show that depression prevalence depends on the macrosocial situation and the adolescence stage. The study aimed to assess changes in depression prevalence in early-adolescents between 1984 and 2001. A presumption was made that the social situation in Poland had changed in the last 17 years. In 2001 a representative sample of school attending 10 y.o. children was screened with KID AO "B I". The results were compared with those of a similar survey, using the same method, carried out in 1984. Point prevalence index in 2001 appeared to be lower than in the survey in 1984 (27.7% versus 38.2%). This resulted exclusively from a significant decrease in depression among boys (31.0% versus 46.6%) and girls (23.9% versus 30.0%). The obtained data allows for an interpretation of the findings as a result of macrosocial changes. Other hypotheses e.g. the influence of the adolescence timing and course require a longitudinal prospective study.
Dutta, Arindam; Kumar, Robins; Malhotra, Suruchi; Chugh, Sanjay; Banerjee, Alakananda; Dutta, Anirban
2013-01-01
The World Health Organization estimated that major depression is the fourth most significant cause of disability worldwide for people aged 65 and older, where depressed older adults reported decreased independence, poor health, poor quality of life, functional decline, disability, and increased chronic medical problems. Therefore, the objectives of this study were (1) to develop a low-cost point-of-care testing system for psychomotor symptoms of depression and (2) to evaluate the system in community dwelling elderly in India. The preliminary results from the cross-sectional study showed a significant negative linear correlation between balance and depression. Here, monitoring quantitative electroencephalography along with the center of pressure for cued response time during functional reach tasks may provide insights into the psychomotor symptoms of depression where average slope of the Theta-Alpha power ratio versus average slope of baseline-normalized response time may be a candidate biomarker, which remains to be evaluated in our future clinical studies. Once validated, the biomarker can be used for monitoring the outcome of a comprehensive therapy program in conjunction with pharmacological interventions. Furthermore, the frequency of falls can be monitored with a mobile phone-based application where the propensity of falls during the periods of psychomotor symptoms of depression can be investigated further.
Experimental realization of self-guided quantum coherence freezing
NASA Astrophysics Data System (ADS)
Yu, Shang; Wang, Yi-Tao; Ke, Zhi-Jin; Liu, Wei; Zhang, Wen-Hao; Chen, Geng; Tang, Jian-Shun; Li, Chuan-Feng; Guo, Guang-Can
2017-12-01
Quantum coherence is the most essential characteristic of quantum physics, specifcially, when it is subject to the resource-theoretical framework, it is considered as the most fundamental resource for quantum techniques. Other quantum resources, e.g., entanglement, are all based on coherence. Therefore, it becomes urgently important to learn how to preserve coherence in quantum channels. The best preservation is coherence freezing, which has been studied recently. However, in these studies, the freezing condition is theoretically calculated, and there still lacks a practical way to achieve this freezing; in addition the channels are usually fixed, but actually, there are also degrees of freedom that can be used to adapt the channels to quantum states. Here we develop a self-guided quantum coherence freezing method, which can guide either the quantum channels (tunable-channel scheme with upgraded channels) or the initial state (fixed-channel scheme) to the coherence-freezing zone from any starting estimate. Specifically, in the fixed-channel scheme, the final-iterative quantum states all satisfy the previously calculated freezing condition. This coincidence demonstrates the validity of our method. Our work will be helpful for the better protection of quantum coherence.
Identification of Arabidopsis mutants with altered freezing tolerance.
Perea-Resa, Carlos; Salinas, Julio
2014-01-01
Low temperature is an important determinant in the configuration of natural plant communities and defines the range of distribution and growth of important crops. Some plants, including Arabidopsis, have evolved sophisticated adaptive mechanisms to tolerate low and freezing temperatures. Central to this adaptation is the process of cold acclimation. By means of this process, many plants from temperate regions are able to develop or increase their freezing tolerance in response to low, nonfreezing temperatures. The identification and characterization of factors involved in freezing tolerance are crucial to understand the molecular mechanisms underlying the cold acclimation response and have a potential interest to improve crop tolerance to freezing temperatures. Many genes implicated in cold acclimation have been identified in numerous plant species by using molecular approaches followed by reverse genetic analysis. Remarkably, however, direct genetic analyses have not been conveniently exploited in their capacity for identifying genes with pivotal roles in that adaptive response. In this chapter, we describe a protocol for evaluating the freezing tolerance of both non-acclimated and cold-acclimated Arabidopsis plants. This protocol allows the accurate and simple screening of mutant collections for the identification of novel factors involved in freezing tolerance and cold acclimation.
Increased spring freezing vulnerability for alpine shrubs under early snowmelt.
Wheeler, J A; Hoch, G; Cortés, A J; Sedlacek, J; Wipf, S; Rixen, C
2014-05-01
Alpine dwarf shrub communities are phenologically linked with snowmelt timing, so early spring exposure may increase risk of freezing damage during early development, and consequently reduce seasonal growth. We examined whether environmental factors (duration of snow cover, elevation) influenced size and the vulnerability of shrubs to spring freezing along elevational gradients and snow microhabitats by modelling the past frequency of spring freezing events. We sampled biomass and measured the size of Salix herbacea, Vaccinium myrtillus, Vaccinium uliginosum and Loiseleuria procumbens in late spring. Leaves were exposed to freezing temperatures to determine the temperature at which 50% of specimens are killed for each species and sampling site. By linking site snowmelt and temperatures to long-term climate measurements, we extrapolated the frequency of spring freezing events at each elevation, snow microhabitat and per species over 37 years. Snowmelt timing was significantly driven by microhabitat effects, but was independent of elevation. Shrub growth was neither enhanced nor reduced by earlier snowmelt, but decreased with elevation. Freezing resistance was strongly species dependent, and did not differ along the elevation or snowmelt gradient. Microclimate extrapolation suggested that potentially lethal freezing events (in May and June) occurred for three of the four species examined. Freezing events never occurred on late snow beds, and increased in frequency with earlier snowmelt and higher elevation. Extrapolated freezing events showed a slight, non-significant increase over the 37-year record. We suggest that earlier snowmelt does not enhance growth in four dominant alpine shrubs, but increases the risk of lethal spring freezing exposure for less freezing-resistant species.
Morphology of supercooled droplets freezing on solid surfaces
NASA Astrophysics Data System (ADS)
La, Shiren; Huang, Zhiting; Liu, Cong; Zhang, Xingyi
2018-05-01
Supercooled droplets freezing on solid surfaces are ubiquitous in nature. This letter investigates the influences of droplet viscosity on freezing velocity and frosting formation. Several experiments were conducted for three kinds of sessile droplets (water, silicone oil and oil) on two types of substrates (copper and iron) with different surface roughness at various temperatures. The results show that the water droplets exhibit obvious phase transition lines and their freezing speeds increase when the temperature of substrates decreases. It is found that the freezing speed is independent of the thermal conductivities of the substrates. Notably, the water droplets develop prominent bulges after freezing and subsequently nucleate to frost. In contrast, the high viscosity oil and silicone oil do not manifest an obvious phase transition line. Besides, no bulges are observed in these two kinds of droplets, suggesting that these frosting forms are of different mechanisms compared with water droplets.
Isochoric and isobaric freezing of fish muscle.
Năstase, Gabriel; Lyu, Chenang; Ukpai, Gideon; Şerban, Alexandru; Rubinsky, Boris
2017-04-01
We have recently shown that, a living organism, which succumbs to freezing to -4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive freezing to -4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the freezing caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric freezing is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, and the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to -5 °C in an isobaric system and c) fresh muscle frozen to -5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric freezing. In contrast, the muscle tissue frozen to -5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric freezing there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact. Copyright © 2017 Elsevier Inc. All rights reserved.
Ignjatovic, Anita Rakic; Miljkovic, Branislava; Todorovic, Dejan; Timotijevic, Ivana; Pokrajac, Milena
2011-05-01
Because moclobemide pharmacokinetics vary considerably among individuals, monitoring of plasma concentrations lends insight into its pharmacokinetic behavior and enhances its rational use in clinical practice. The aim of this study was to evaluate whether single concentration-time points could adequately predict moclobemide systemic exposure. Pharmacokinetic data (full 7-point pharmacokinetic profiles), obtained from 21 depressive inpatients receiving moclobemide (150 mg 3 times daily), were randomly split into development (n = 18) and validation (n = 16) sets. Correlations between the single concentration-time points and the area under the concentration-time curve within a 6-hour dosing interval at steady-state (AUC(0-6)) were assessed by linear regression analyses. The predictive performance of single-point sampling strategies was evaluated in the validation set by mean prediction error, mean absolute error, and root mean square error. Plasma concentrations in the absorption phase yielded unsatisfactory predictions of moclobemide AUC(0-6). The best estimation of AUC(0-6) was achieved from concentrations at 4 and 6 hours following dosing. As the most reliable surrogate for moclobemide systemic exposure, concentrations at 4 and 6 hours should be used instead of predose trough concentrations as an indicator of between-patient variability and a guide for dose adjustments in specific clinical situations.
Freeze-dried dog sperm: Dynamics of DNA integrity.
Olaciregui, M; Luño, V; Gonzalez, N; De Blas, I; Gil, L
2015-10-01
Freeze-drying (FD) has been proposed as an alternative method to preserve spermatozoa. During the FD procedure, sperm DNA might become damaged by both freezing and drying stresses caused by the endonucleases, the oxidative stress and the storage conditions. We examined the DNA integrity of dog sperm freeze-dried with two kinds of chelating agents in FD buffers and storage at two different temperatures. Ejaculated sperm from four dogs were suspended in basic medium (10 mM Tris-HCl buffer+50 mM NaCl) supplemented with 50 mM EGTA or with 50 mM EDTA and then freeze-dried. Sperm samples were stored at 4°C as room temperature, and the analysis of DNA damage was performed after a month and 5 months of storage using a Sperm Chromatin Dispersion test. We found four different sperm populations according to the size of the halos around the sperm head: (1) absent halo, (2) <6 μm, (3) 6-10 μm, (4) >10 μm. All of them coexisted in each freeze-dried dog semen samples and differed significantly among different treatments. The highest percentage of spermatozoa with halo >10 μm was obtained when the semen samples were freeze-dried in EDTA medium and stored at room temperature for five months. Results suggested that both, the kind of chelating agent as well as storage temperature and period, influenced DNA integrity of freeze-dried dog sperm. Copyright © 2015 Elsevier Inc. All rights reserved.
Costanzo, J P; Lee, R E; DeVries, A L; Wang, T; Layne, J R
1995-03-01
Various marine fishes, amphibians, and reptiles survive at temperatures several degrees below the freezing point of their body fluids by virtue of adaptive mechanisms that promote freeze avoidance or freeze tolerance. Freezing is avoided by a colligative depression of the blood freezing point, supercooling of the body fluids, or the biosynthesis of unique antifreeze proteins that inhibit the propagation of ice within body fluids. Conversely, freeze tolerance is an adaptation for the survival of tissue freezing under ecologically relevant thermal and temporal conditions that is conferred by the biosynthesis of permeating carbohydrate cryoprotectants and an extensive dehydration of tissues and organs. Such cryoprotective responses, invoked by the onset of freezing, mitigate the osmotic stress associated with freeze-concentration of cytoplasm, attendant metabolic perturbations, and physical damage. Cryomedical research has historically relied on mammalian models for experimentation even though endotherms do not naturally experience subfreezing temperatures. Some vertebrate ectotherms have "solved" not only the problem of freezing individual tissues and organs, but also that of simultaneously freezing all organ systems. An emerging paradigm in cryomedicine is the application of principles governing natural cold hardiness to the development of protocols for the cryopreservation of mammalian tissues and organs.
NASA Astrophysics Data System (ADS)
Yu, Yongxiang; Zhang, Zheng; Wang, Yingeng; Liao, Meijie; Li, Bin; Xue, Liangyi
2017-10-01
Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. Freeze-drying is such a method usually used for preservation of terrigenous bacteria. However, studies using freeze-drying method to preserving marine microorganisms remain very limited. In this study, we optimized the composition of protectants during the freeze-drying of Edwardsiella tarda, a fish pathogen that causes systemic infection in marine fishes. We found that the optimal composition of protectant mixture contained trehalose (8.0%), skim milk (12.0%), sodium citrate (2.0%), serum (12.0%) and PVP (2.0%). Orthogonal and interaction analyses demonstrated the interaction between serum and skim milk or sodium citrate. The highest survival rate of E. tarda was observed when the concentration of NaCl was 10.0, 30.0 and between 5.0 and 10.0 g L-1 for preparing TSB medium, E. tarda suspension and protectant mixture, respectively. When E. tarda was frozen at -80°C or -40°C for 6 h, its survival rate was higher than that under other tested conditions. Under the optimized conditions, when the protectant mixture was used during freeze-drying process, the survival rate (79.63%-82.30%) of E. tarda was significantly higher than that obtained using single protectant. Scanning electron microscopy (SEM) image indicated that E. tarda was embedded in thick matrix with detectable aggregation. In sum, the protectant mixture may be used as a novel cryoprotective additive for E. tarda.
NIM Realization of the Gallium Triple Point
NASA Astrophysics Data System (ADS)
Xiaoke, Yan; Ping, Qiu; Yuning, Duan; Yongmei, Qu
2003-09-01
In the last three years (1999 to 2001), the gallium triple-point cell has been successfully developed, and much corresponding research has been carried out at the National Institute of Metrology (NIM), Beijing, China. This paper presents the cell design, apparatus and procedure for realizing the gallium triple point, and presents studies on the different freezing methods. The reproducibility is 0.03 mK, and the expanded uncertainty of realization of the gallium triple point is evaluated to be 0.17 mK (p=0.99, k=2.9). Also, the reproducibility of the gallium triple point was compared with that of the triple point of water.
Mutagenic effect of freezing on mitochondrial DNA of Saccharomyces cerevisiae.
Stoycheva, T; Venkov, P; Tsvetkov, Ts
2007-06-01
Although suggested in some studies, the mutagenic effect of freezing has not been proved by induction and isolation of mutants. Using a well-defined genetic model, we supply in this communication evidence for the mutagenic effect of freezing on mitochondrial DNA (mtDNA) of the yeast Saccharomyces cerevisiae. The cooling for 2 h at +4 degrees C, followed by freezing for 1 h at -10 degrees C and 16 h at -20 degrees C resulted in induction of respiratory mutations. The immediate freezing in liquid nitrogen was without mutagenic effect. The study of the stepwise procedure showed that the induction of respiratory mutants takes place during the freezing at -10 and -20 degrees C of cells pre-cooled at +4 degrees C. The genetic crosses of freeze-induced mutants evidenced their mitochondrial rho- origin. The freeze-induced rho- mutants are most likely free of simultaneous nuclear mutations. The extracellular presence of cryoprotectants did not prevent the mutagenic effect of freezing while accumulation of cryoprotectors inside cells completely escaped mtDNA from cryodamage. Although the results obtained favor the notion that the mutagenic effect of freezing on yeast mtDNA is due to formation and growth of intracellular ice crystals, other reasons, such as impairment of mtDNA replication or elevated levels of ROS production are discussed as possible explanations of the mutagenic effect of freezing. It is concluded that: (i) freezing can be used as a method for isolation of mitochondrial mutants in S. cerevisiae and (ii) given the substantial development in cryopreservation of cells and tissues, special precautions should be made to avoid mtDNA damage during the cryopreservation procedures.
Natural genetic variation of freezing tolerance in Arabidopsis.
Hannah, Matthew A; Wiese, Dana; Freund, Susanne; Fiehn, Oliver; Heyer, Arnd G; Hincha, Dirk K
2006-09-01
Low temperature is a primary determinant of plant growth and survival. Using accessions of Arabidopsis (Arabidopsis thaliana) originating from Scandinavia to the Cape Verde Islands, we show that freezing tolerance of natural accessions correlates with habitat winter temperatures, identifying low temperature as an important selective pressure for Arabidopsis. Combined metabolite and transcript profiling show that during cold exposure, global changes of transcripts, but not of metabolites, correlate with the ability of Arabidopsis to cold acclimate. There are, however, metabolites and transcripts, including several transcription factors, that correlate with freezing tolerance, indicating regulatory pathways that may be of primary importance for this trait. These data identify that enhanced freezing tolerance is associated with the down-regulation of photosynthesis and hormonal responses and the induction of flavonoid metabolism, provide evidence for naturally increased nonacclimated freezing tolerance due to the constitutive activation of the C-repeat binding factors pathway, and identify candidate transcriptional regulators that correlate with freezing tolerance.
The Impact of Freeze-Thaw Cycles on Epinephrine.
Beasley, Heather; Ng, Pearlly; Wheeler, Albert; Smith, William R; McIntosh, Scott E
2015-12-01
Epinephrine is the first-line medical treatment for anaphylaxis, a life-threatening allergic syndrome. To treat anaphylaxis, backcountry recreationalists and guides commonly carry epinephrine autoinjectors. Epinephrine may be exposed to cold temperatures and freezing during expeditions. An epinephrine solution must contain 90% to 115% of the labeled epinephrine amount to meet United States Pharmacopeia standards. The purpose of this study was to determine whether freeze-thaw cycles alter epinephrine concentrations in autoinjectors labeled to contain 1.0 mg/mL epinephrine. A further objective was to determine whether samples continued to meet United States Pharmacopeia concentration standards after freeze-thaw cycles. Epinephrine from 6 autoinjectors was extracted and divided into experimental and control samples. The experimental samples underwent 7 consecutive 12-hour freeze cycles followed by 7 12-hour thaw cycles. The control samples remained at an average temperature of 23.1°C for the duration of the study. After the seventh thaw cycle, epinephrine concentrations were measured using a high-performance liquid chromatography assay with mass spectrometry detection. The mean epinephrine concentration of the freeze-thaw samples demonstrated a statistically significant increase compared with the control samples: 1.07 mg/mL (SD ± 8.78; 95% CI, 1.04 to 1.11) versus 0.96 mg/mL (SD ± 6.81; 95% CI, 0.94 to 0.99), respectively. The maximal mean epinephrine concentration in the experimental freeze-thaw group was 1.12 mg/mL, which still fell within the range of United States Pharmacopeia standards for injectables (0.90 to 1.15 mg/mL). Although every attempt should be made to prevent freezing of autoinjectors, this preliminary study demonstrates that epinephrine concentrations remain within 90% to 115% of 1.0 mg/mL after multiple freeze-thaw cycles. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.
2009-11-12
A scaffolding structure built around NASA Wide-field Infrared Survey Explorer allows engineers to freeze its hydrogen coolant. The WISE infrared instrument is kept extremely cold by a bottle-like tank filled with frozen hydrogen, called the cryostat.
Freeze-thaw durability of concrete: Ice formation process in pores
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cai, H.; Liu, X.
1998-09-01
Freeze-thaw durability of concrete is of great importance to hydraulic structures in cold areas. Study of ice formation process in concrete pores is necessary to evaluate the damages in concrete caused by freezing. In this paper, freezing of pore solution in concrete exposed to a freeze-thaw cycle is studied by following the change of concrete electrical conductivity with freezing temperatures. Concretes were subjected to freeze-thaw cycles with temperature varying between {minus}0 C and {minus}20 C. In the freezing process, the changing rate of concrete electrical conductivity obviously decreases at about {minus}10 C, indicating that more pore solution in concrete freezesmore » above {minus}10 C than below {minus}10C. According to Powers` static hydraulic pressure hypothesis, it is thought that frost damage mainly occurs between 0 C and {minus}100 C. To ordinary concrete, frost damages below {minus}10 C are negligible.« less
Mechanisms of deterioration of nutrients. [improved quality of freeze-dried foods
NASA Technical Reports Server (NTRS)
Karel, M.; Flink, J. M.
1978-01-01
Methods for improving the quality of freeze-dried foods were investigated. Areas discussed include: (1) microstructure of freeze-dried systems, (2) structural changes in freeze-dried systems, (3) artificial food matrices, and (4) osmotic preconcentration to yield improved freeze-dried products.
Water freezing and ice melting
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, T S(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 cubicmore » 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.« less
Design of freeze-drying processes for pharmaceuticals: practical advice.
Tang, Xiaolin; Pikal, Michael J
2004-02-01
Design of freeze-drying processes is often approached with a "trial and error" experimental plan or, worse yet, the protocol used in the first laboratory run is adopted without further attempts at optimization. Consequently, commercial freeze-drying processes are often neither robust nor efficient. It is our thesis that design of an "optimized" freeze-drying process is not particularly difficult for most products, as long as some simple rules based on well-accepted scientific principles are followed. It is the purpose of this review to discuss the scientific foundations of the freeze-drying process design and then to consolidate these principles into a set of guidelines for rational process design and optimization. General advice is given concerning common stability issues with proteins, but unusual and difficult stability issues are beyond the scope of this review. Control of ice nucleation and crystallization during the freezing step is discussed, and the impact of freezing on the rest of the process and final product quality is reviewed. Representative freezing protocols are presented. The significance of the collapse temperature and the thermal transition, denoted Tg', are discussed, and procedures for the selection of the "target product temperature" for primary drying are presented. Furthermore, guidelines are given for selection of the optimal shelf temperature and chamber pressure settings required to achieve the target product temperature without thermal and/or mass transfer overload of the freeze dryer. Finally, guidelines and "rules" for optimization of secondary drying and representative secondary drying protocols are presented.
Cost-Effectiveness of the Freeze-All Policy.
Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo
2015-08-01
To evaluate the cost-effectiveness of freeze-all cycles when compared to fresh embryo transfer. This was an observational study with a cost-effectiveness analysis. The analysis consisted of 530 intracytoplasmic sperm injection (ICSI) cycles in a private center in Brazil between January 2012 and December 2013. A total of 530 intracytoplasmic sperm injection (ICSI) cycles - 351 fresh embryo transfers and 179 freeze-all cycles - with a gonadotropin-releasing hormone (GnRH) antagonist protocol and day 3 embryo transfers. The pregnancy rate was 31.1% in the fresh group and 39.7% in the freeze-all group. We performed two scenario analyses for costs. In scenario 1, we included those costs associated with the ICSI cycle (monitoring during controlled ovarian stimulation [COS], oocyte retrieval, embryo transfer, IVF laboratory, and medical costs), embryo cryopreservation of supernumerary embryos, hormone measurements during COS and endometrial priming, medication use (during COS, endometrial priming, and luteal phase support), ultrasound scan for frozen- thawed embryo transfer (FET), obstetric ultrasounds, and miscarriage. The total cost (in USD) per pregnancy was statistically lower in the freeze-all cycles (19,156.73 ± 1,732.99) when compared to the fresh cycles (23,059.72 ± 2,347.02). Even in Scenario 2, when charging all of the patients in the freeze-all group for cryopreservation (regardless of supernumerary embryos) and for FET, the fresh cycles had a statistically significant increase in treatment costs per ongoing pregnancy. The results presented in this study suggest that the freeze-all policy is a cost-effective strategy when compared to fresh embryo transfer.
Zhang, Lin; Zhong, Yan; Quan, Shulin; Liu, Yehui; Shi, Xuehui; Li, Zhenguang; Wang, Jingjing
2017-06-12
To observe the clinical effects of acupuncture combined with auricular point sticking based on the western medication for post stroke depression (PSD). Sixty patients with PSD were randomly assigned into an acupuncture plus auricular application group (a combination group) and a medication group, 30 cases in each one. 20 mg paroxetine hydrochloride was prescribed orally in the medication group, once a day for continuous 8 weeks. Based on the above treatment, 30-minute acupuncture was used in the combination group for 8 weeks at Baihui (GV 20), Sishencong (EX-HN 1), Shenting (GV 24), Yintang (GV 29), Shenmen (HT 7), Neiguan (PC 6), Taichong (LR 3), Hegu (LI 4), Zusanli (ST 36), Sanyinjiao (SP 6) and Fenglong (ST 40), once the other day and three times a week. Auricular point sticking therapy for 8 weeks was applied at shenmen (TF 4 ), pizhixia (AT 4 ), xin (CO 15 ), and gan (CO 12 ), with pressing 3 times a day and once 3-5 days. The total score and each factor scores of Hamilton's depression scale (HAMD) were observed in the two groups before and after treatment, and Asberg's antidepressant side-effect rating scale (SERS) and clinical effect were evaluated. After treatment, the total HAMD scores of the two groups decreased compared with those before treatment (both P <0.05), with better effect in the combination group ( P <0.05). The scores of the combination group after treatment were lower than those in the medication group, including the anxiety/somatization factor, sleep disturbance factor, hopelessness factor (all P <0.05). The total effective rate of the combination group was 86.7% (26/30), which was better than 66.7% (20/30) of the medication group ( P <0.05). The SERS score of the combination group was lower than that of the medication group ( P <0.05). Acupuncture combined with auricular point sticking can improve the clinical symptoms and are effective and safe for PSD.
Thermalization, Freeze-out, and Noise: Deciphering Experimental Quantum Annealers
NASA Astrophysics Data System (ADS)
Marshall, Jeffrey; Rieffel, Eleanor G.; Hen, Itay
2017-12-01
By contrasting the performance of two quantum annealers operating at different temperatures, we address recent questions related to the role of temperature in these devices and their function as "Boltzmann samplers." Using a method to reliably calculate the degeneracies of the energy levels of large-scale spin-glass instances, we are able to estimate the instance-dependent effective temperature from the output of annealing runs. Our results corroborate the "freeze-out" picture which posits two regimes, one in which the final state corresponds to a Boltzmann distribution of the final Hamiltonian with a well-defined "effective temperature" determined at a freeze-out point late in the annealing schedule, and another regime in which such a distribution is not necessarily expected. We find that the output distributions of the annealers do not, in general, correspond to a classical Boltzmann distribution for the final Hamiltonian. We also find that the effective temperatures at different programing cycles fluctuate greatly, with the effect worsening with problem size. We discuss the implications of our results for the design of future quantum annealers to act as more-effective Boltzmann samplers and for the programing of such annealers.
Metabolic Changes in Avena sativa Crowns Recovering from Freezing
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
Applications of Simulator Freeze to Carrier Glideslope Tracking Instruction.
1982-07-01
Showing Datum Bars and Meatball . .. .. .. ... .. ... .... 19 4 Freezes Per Trial Averaged Across Freeze Conditions and Across 4-Trial Blocks of Training...algorithm linearly increased the criterion in meatball units from 1.0 at 6000 feet from the ramp to 1.5 at the ramp. "Freezes" did not occur beyond 6000
Silicon-based Porous Ceramics via Freeze Casting of Preceramic Polymers
NASA Astrophysics Data System (ADS)
Naviroj, Maninpat
Freeze casting is a technique for processing porous materials that has drawn significant attention for its effectiveness in producing a variety of tailorable pore structures for ceramics, metals, and polymers. With freeze casting, pores are generated based on a solidification process where ice crystals act as a sacrificial template which can eventually be sublimated to create pores. While the majority of freeze-casting studies have been performed using conventional ceramic suspensions, this work explores an alternative processing route by freeze casting with preceramic polymer solutions. Significant differences exist between freeze casting of a particulate suspension and a polymeric solution. These changes affect the processing method, solidification behavior, and pore structure, thereby introducing new challenges and possibilities for the freeze-casting technique. The first part of this study explored the processing requirements involved with freeze casting of preceramic polymers, along with methods to control the resulting pore structure. Solvent choice, freezing front velocity, and polymer concentration were used as processing variables to manipulate the pore structures. A total of seven organic solvents were freeze cast with a polymethylsiloxane preceramic polymer to produce ceramics with isotropic, dendritic, prismatic, and lamellar pore morphologies. Changes in freezing front velocity and polymer concentration were shown to influence pore size, shape, and connectivity. Differences between suspension- and solution-based samples freeze cast under equivalent conditions were also investigated. Certain solidification microstructures were strongly affected by the presence of suspended particles, creating differences between pore structures generated from the same solvents. Additionally, processing of solution-based samples were found to be the more facile technique. Compressive strength and water permeability of dendritic and lamellar structures were analyzed to
Freezing, melting and structure of ice in a hydrophilic nanopore.
Moore, Emily B; de la Llave, Ezequiel; Welke, Kai; Scherlis, Damian A; Molinero, Valeria
2010-04-28
The nucleation, growth, structure and melting of ice in 3 nm diameter hydrophilic nanopores are studied through molecular dynamics simulations with the mW water model. The melting temperature of water in the pore was T(m)(pore) = 223 K, 51 K lower than the melting point of bulk water in the model and in excellent agreement with experimental determinations for 3 nm silica pores. Liquid and ice coexist in equilibrium at the melting point and down to temperatures as low as 180 K. Liquid water is located at the interface of the pore wall, increasing from one monolayer at the freezing temperature, T(f)(pore) = 195 K, to two monolayers a few degrees below T(m)(pore). Crystallization of ice in the pore occurs through homogeneous nucleation. At the freezing temperature, the critical nucleus contains approximately 75 to 100 molecules, with a radius of gyration similar to the radius of the pore. The critical nuclei contain features of both cubic and hexagonal ice, although stacking of hexagonal and cubic layers is not defined until the nuclei reach approximately 150 molecules. The structure of the confined ice is rich in stacking faults, in agreement with the interpretation of X-ray and neutron diffraction experiments. Though the presence of cubic layers is twice as prevalent as hexagonal ones, the crystals should not be considered defective Ic as sequences with more than three adjacent cubic (or hexagonal) layers are extremely rare in the confined ice.
Freeze-In dark matter with displaced signatures at colliders
DOE Office of Scientific and Technical Information (OSTI.GOV)
Co, Raymond T.; D’Eramo, Francesco; Hall, Lawrence J.
2015-12-11
Dark matter, X, may be generated by new physics at the TeV scale during an early matter-dominated (MD) era that ends at temperature T{sub R}≪ TeV. Compared to the conventional radiation-dominated (RD) results, yields from both Freeze-Out and Freeze-In processes are greatly suppressed by dilution from entropy production, making Freeze-Out less plausible while allowing successful Freeze-In with a much larger coupling strength. Freeze-In is typically dominated by the decay of a particle B of the thermal bath, B→X. For a large fraction of the relevant cosmological parameter space, the decay rate required to produce the observed dark matter abundance leadsmore » to displaced signals at LHC and future colliders, for any m{sub X} in the range keV« less
NASA Astrophysics Data System (ADS)
Sliwinska-Bartkowiak, Malgorzata; Dudziak, Grazyna; Sikorski, Roman; Gras, Roman; Radhakrishnan, Ravi; Gubbins, Keith E.
2001-01-01
We report both experimental measurements and molecular simulations of the melting and freezing behavior of fluids in nanoporous media. The experimental studies are for nitrobenzene in the silica-based pores of controlled pore glass, Vycor, and MCM-41. Dielectric relaxation spectroscopy is used to determine melting points and the orientational relaxation times of the nitrobenzene molecules in the bulk and the confined phase. Monte Carlo simulations, together with a bond orientational order parameter method, are used to determine the melting point and fluid structure inside cylindrical pores modeled on silica. Qualitative comparison between experiment and simulation are made for the shift in the freezing temperatures and the structure of confined phases. From both the experiments and the simulations, it is found that the confined fluid freezes into a single crystalline structure for average pore diameters greater than 20σ, where σ is the diameter of the fluid molecule. For average pore sizes between 20σ and 15σ, part of the confined fluid freezes into a frustrated crystal structure with the rest forming an amorphous region. For pore sizes smaller than 15σ, even the partial crystallization did not occur. Our measurements and calculations show clear evidence of a novel intermediate "contact layer" phase lying between liquid and crystal; the contact layer is the confined molecular layer adjacent to the pore wall and experiences a deeper fluid-wall potential energy compared to the inner layers. We also find evidence of a liquid to "hexatic" transition in the quasi-two-dimensional contact layer at high temperatures.
Wang, T; Zhu, Q; Yang, X; Layne, J R; Devries, A L
1994-04-01
The antarctic notothenioid fishes avoid freezing through the action of circulating antifreeze glycoproteins (AFGPs). This study investigated whether AFGPs could serve as cryoprotectants for the isolated rat heart under three different storage conditions. (1) Hearts were flushed with 15 mg AFGP/ml cardioplegic solution (CP) and stored for 9 h at 0 degrees C. This AFGP concentration has been reported to protect pig oocytes during hypothermic storage. (2) Hearts were flushed with 10 mg AFGP/ml CP-14 and stored frozen at -1.4 degrees C for 3 h. At this concentration the AFGPs significantly reduce the solution freezing point and also change the crystal morphology from dendritic to spicular. (3) Hearts were flushed with 10 micrograms AFGP/ml CP-15 and stored frozen at -1.4 degrees C for 5 h. At this low concentration the AFGPs have a strong inhibitory effect on ice recrystallization, but have little effect on the freezing point and less apparent effect on the crystal habit. After hypothermic or freezing storage, the functional viability was assessed by determining cardiac output (CO) during working reperfusion. No difference in CO was found between AFGP-treated and untreated hearts after 9 h of 0 degree C storage. CO in hearts frozen in CP-14 without AFGPs recovered to 50% of the freshly perfused control hearts. Hearts frozen in the presence of high concentrations of AFGPs (10 mg/ml CP-14) failed to beat upon thawing and reperfusion, although their tissue ice content was less than that found in hearts without AFGP treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
DOE Office of Scientific and Technical Information (OSTI.GOV)
Knopf, Daniel A.; Alpert, Peter A.
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, aw, 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 humiditymore » (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw 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, Jhet, 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 log 10(J het) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can
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
Knopf, Daniel A.; Alpert, Peter A.
2013-04-24
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, aw, 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 humiditymore » (RH). This allows the freezing point and corresponding heterogeneous ice nucleation rate coefficient, Jhet, to be uniquely expressed by T and aw, a result we term the aw 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, Jhet, 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 log 10(J het) values for the various IN types derived exclusively by T and aw, provide a complete description of the heterogeneous ice nucleation kinetics. Thus, the ABIFM can be applied over the entire range of T, RH, total particulate surface area, and cloud activation timescales typical of atmospheric conditions. Finally, we demonstrate that ABIFM can
7 CFR 929.11 - To can, freeze, or dehydrate.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 8 2010-01-01 2010-01-01 false To can, freeze, or dehydrate. 929.11 Section 929.11... LONG ISLAND IN THE STATE OF NEW YORK Order Regulating Handling Definitions § 929.11 To can, freeze, or dehydrate. To can, freeze, or dehydrate means to convert cranberries into canned, frozen, or dehydrated...
Immersion freezing of ambient dust using WISDOM setup
NASA Astrophysics Data System (ADS)
Rudich, Y.; Reicher, N.
2017-12-01
A small subset of the atmospheric particles has the ability to induce ice formation. Among them are mineral dust particles that originate from arid regions. Mineral dust particles are internally mixed with various types of minerals such as kaolinite and illite from the clay minerals, quartz and feldspar. The mineral composition of the dust particles determine their freezing efficiency. Much attention was given to the clay group, as they are the most common minerals transported in the atmosphere. Recently, much focus has been directed to the feldspars, since its ice efficiency is higher at warmer temperatures, and as such is may dominate freezing in mixed phase clouds. Moreover, it was found that samples that contained higher content of feldspar had higher nucleation activity. In this study, we examine the immersion freezing of ambient dust particles that were collected in Rehovot, Israel (31.9N, 34.8E about 80m AMSL), during dust storms from the Sahara and the Syrian deserts. The size-segregated dust particles were collected on cyclopore polycarbonate filters using a Micro-orifice Uniform deposit Impactor (MOUDI). Freezing experiments were done using the WeIzmann Supercooled Droplets Observation on Microarray set (WISDOM). The particles were extracted from the filters by sonication and subsequently immersed in 100μm droplets that were cooled in a rate of 1°CPM to -37°C (homogenous freezing threshold). Investigation of the particles mineralogy was also performed. We observed freezing onset at 253K for particles of different diameters (0.3, 1.0, 1.8 and 3.2 μm). Most of the droplets were completely frozen by 243K. The number of active sites ranged from 108 to 1012 per m-2. Droplets that contained larger particles (higher surface area) froze at slightly warmer temperatures and contained slightly higher number of active sites. The freezing behavior fits well with measurements of K-feldspar particles and this may suggest that the feldspar dominated the dust freezing
Ice nucleation and antinucleation in nature.
Zachariassen, K E; Kristiansen, E
2000-12-01
Plants and ectothermic animals use a variety of substances and mechanisms to survive exposure to subfreezing temperatures. Proteinaceous ice nucleators trigger freezing at high subzero temperatures, either to provide cold protection from released heat of fusion or to establish a protective extracellular freezing in freeze-tolerant species. Freeze-avoiding species increase their supercooling potential by removing ice nucleators and accumulating polyols. Terrestrial invertebrates and polar marine fish stabilize their supercooled state by means of noncolligatively acting antifreeze proteins. Some organisms also depress their body fluid melting point to ambient temperature by evaporation and/or solute accumulation. Copyright 2000 Academic Press.
Chen, Jing; Han, Guiqing; Shang, Chen; Li, Jikai; Zhang, Hailing; Liu, Fengqi; Wang, Jianli; Liu, Huiying; Zhang, Yuexue
2015-01-01
Cold acclimation in alfalfa (Medicago sativa L.) plays a crucial role in cold tolerance to harsh winters. To examine the cold acclimation mechanisms in freezing-tolerant alfalfa (ZD) and freezing-sensitive alfalfa (W5), holoproteins, and low-abundance proteins (after the removal of RuBisCO) from leaves were extracted to analyze differences at the protein level. A total of 84 spots were selected, and 67 spots were identified. Of these, the abundance of 49 spots and 24 spots in ZD and W5, respectively, were altered during adaptation to chilling stress. Proteomic results revealed that proteins involved in photosynthesis, protein metabolism, energy metabolism, stress and redox and other proteins were mobilized in adaptation to chilling stress. In ZD, a greater number of changes were observed in proteins, and autologous metabolism and biosynthesis were slowed in response to chilling stress, thereby reducing consumption, allowing for homeostasis. The capability for protein folding and protein biosynthesis in W5 was enhanced, which allows protection against chilling stress. The ability to perceive low temperatures was more sensitive in freezing-tolerant alfalfa compared to freezing-sensitive alfalfa. This proteomics study provides new insights into the cold acclimation mechanism in alfalfa. PMID:25774161
Deposition Nucleation or Pore Condensation and Freezing?
NASA Astrophysics Data System (ADS)
David, Robert O.; Mahrt, Fabian; Marcolli, Claudia; Fahrni, Jonas; Brühwiler, Dominik; Lohmann, Ulrike; Kanji, Zamin A.
2017-04-01
Ice nucleation plays an important role in moderating Earth's climate and precipitation formation. Over the last century of research, several mechanisms for the nucleation of ice have been identified. Of the known mechanisms for ice nucleation, only deposition nucleation occurs below water saturation. Deposition nucleation is defined as the formation of ice from supersaturated water vapor on an insoluble particle without the prior formation of liquid. However, recent work has found that the efficiency of so-called deposition nucleation shows a dependence on the homogeneous freezing temperature of water even though no liquid phase is presumed to be present. Additionally, the ability of certain particles to nucleate ice more efficiently after being pre-cooled (pre-activation) raises questions on the true mechanism when ice nucleation occurs below water saturation. In an attempt to explain the dependence of the efficiency of so-called deposition nucleation on the onset of homogeneous freezing of liquid water, pore condensation and freezing has been proposed. Pore condensation and freezing suggests that the liquid phase can exist under sub-saturated conditions with respect to liquid in narrow confinements or pores due to the inverse Kelvin effect. Once the liquid-phase condenses, it is capable of nucleating ice either homogeneously or heterogeneously. The role of pore condensation and freezing is assessed in the Zurich Ice Nucleation Chamber, a continuous flow diffusion chamber, using spherical nonporous and mesoporous silica particles. The mesoporous silica particles have a well-defined particle size range of 400 to 600nm with discreet pore sizes of 2.5, 2.8, 3.5 and 3.8nm. Experiments conducted between 218K and 238K show that so-called deposition nucleation only occurs below the homogenous freezing temperature of water and is highly dependent on the presence of pores and their size. The results strongly support pore condensation and freezing, questioning the role of
Predictive modeling of freezing and thawing of frost-susceptible soils.
DOT National Transportation Integrated Search
2015-09-01
Frost depth is an essential factor in design of various transportation infrastructures. In frost : susceptible soils, as soils freezes, water migrates through the soil voids below the freezing line : towards the freezing front and causes excessive he...
Experimental Study of Low Temperature Behavior of Aviation Turbine Fuels in a Wing Tank Model
NASA Technical Reports Server (NTRS)
Stockemer, Francis J.
1979-01-01
An experimental investigation was performed to study aircraft fuels at low temperatures near the freezing point. The objective was an improved understanding of the flowability and pumpability of the fuels under conditions encoutered during cold weather flight of a long range commercial aircraft. The test tank simulated a section of an outer wing tank and was chilled on the upper and lower surfaces. Fuels included commercial Jet A and Diesel D-2; JP-5 from oil shale; and Jet A, intermediate freeze point, and D-2 fuels derived from selected paraffinic and naphthenic crudes. A pour point depressant was tested.
Multiple Glass Transitions and Freezing Events of Aqueous Citric Acid
2014-01-01
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. PMID:25482069
Application of freeze-drying technology in manufacturing orally disintegrating films.
Liew, Kai Bin; Odeniyi, Michael Ayodele; Peh, Kok-Khiang
2016-01-01
Freeze drying technology has not been maximized and reported in manufacturing orally disintegrating films. The aim of this study was to explore the freeze drying technology in the formulation of sildenafil orally disintegrating films and compare the physical properties with heat-dried orally disintegrating film. Central composite design was used to investigate the effects of three factors, namely concentration of carbopol, wheat starch and polyethylene glycol 400 on the tensile strength and disintegration time of the film. Heat-dried films had higher tensile strength than films prepared using freeze-dried method. For folding endurance, freeze-dried films showed improved endurance than heat-dried films. Moreover, films prepared using freeze-dried methods were thicker and had faster disintegration time. Formulations with higher amount of carbopol and starch showed higher tensile strength and thickness whereas formulations with higher PEG 400 content showed better flexibility. Scanning electron microscopy showed that the freeze-dried films had more porous structure compared to the heat-dried film as a result of the release of water molecule from the frozen structure when it was subjected to freeze drying process. The sildenafil film was palatable. The dissolution profiles of freeze-dried and heat-dried films were similar to Viagra® with f2 of 51.04 and 65.98, respectively.
Three-Dimensional Microstructure of Biological Tissues during Freezing and Thawing
NASA Astrophysics Data System (ADS)
Ishiguro, Hiroshi; Horimizu, Takashi; Kataori, Akinobu; Kajigaya, Hiroshi
Three-dimensional behavior of ice crystals and cells during the freezing and thawing of biological tissues was investigated microscopically in real time by using a confocal laser scanning microscope(CLSM) and a fluorescent dye, acridine orange (AO). Fresh tender meat (2nd pectoral muscles) of chicken was stained with the AO in physiological saline to distinguish ice crystals and cells by their different colors, and then frozen and thawed under two different thermal protocols: a) slow-cooling and rapid-warming and b) rapid-cooling and rapid-warming. The CLSM noninvasively produced optical tomograms of the tissues to clarify the pattern of freezing, morphology of ice crystals in the tissues, and the interaction between ice crystals and cells. Also, the tissues were morphologically investigated by pathological means after the freezing and thawing. Typical freezing pattern during the slow-cooling was extracellular-freezing, and those during the rapid-cooling were extracellular-freezing and intracellular freezing with a lot of fine ice crystals in the cells. Cracks caused by the extracellular and intracellular ice crystals remained in the muscle tissues after the thawing. The results obtained by using the CLSM/dye method were consistent with pathologically morphological changes in the tissues through freezing and thawing.
Dumont, Frédéric; Marechal, Pierre-André; Gervais, Patrick
2006-02-01
The purpose of this study was to examine cell viability after freezing. Two distinct ranges of temperature were identified as corresponding to stages at which yeast cell mortality occurred during freezing to -196 degrees C. The upper temperature range was related to the temperature of crystallization of the medium, which was dependent on the solute concentration; in this range mortality was prevented by high solute concentrations, and the proportion of the medium in the vitreous state was greater than the proportion in the crystallized state. The lower temperature range was related to recrystallization that occurred during thawing. Mortality in this temperature range was increased by a high cooling rate and/or high solute concentration in the freezing medium and a low temperature (less than -70 degrees C). However, a high rate of thawing prevented yeast mortality in this lower temperature range. Overall, it was found that cell viability could be conserved better under freezing conditions by increasing the osmotic pressure of the medium and by using an increased warming rate.
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.
An RNA-Cleaving Catalytic DNA Accelerated by Freezing.
Yu, Tianmeng; Zhou, Wenhu; Liu, Juewen
2018-05-18
The EtNa DNAzyme was isolated during the isopropanol precipitation step of an in vitro selection effort. Although inactive with the intended cofactor, its RNA cleavage activity was observed under a few conditions. With Na + , EtNa was highly active in ∼50 % ethanol, whereas in water, it was highly active with Ca 2+ . In this work, we showed that the EtNa DNAzyme was accelerated by freezing in water in the presence of Na + . The apparent K d value reached 6.2 mm Na + under the frozen condition, over 20 times tighter than that in water at room temperature. With 10 mm Na + , EtNa had a cleavage rate of 0.12 h -1 after freezing at -20 °C. This effect was unique to EtNa, as all other tested DNAzymes were inhibited by freezing except for the Na + -specific NaA43. Freezing also inhibited EtNa if Ca 2+ was used. We attributed this to the concentrations of EtNa and Na + in the micropockets between ice crystals, but divalent metals might misfold DNA. Overall, we have systematically studied the effect of freezing on the RNA-cleavage activity of DNAzymes. The DNAzyme sequence and the metal ion species are both crucial to determine the effect of freezing. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Schoville, Sean D; Slatyer, Rachel A; Bergdahl, James C; Valdez, Glenda A
2015-07-01
For many terrestrial species, habitat associations and range size are dependent on physiological limits, which in turn may influence large-scale patterns of species diversity. The temperature range experienced by individuals is considered to shape the breadth of the thermal niche, with species occupying temporally and/or geographically stable climates tolerating a narrow temperature range. High-elevation environments experience large temperature fluctuations, with frequent periods below 0 °C, but Grylloblatta (Grylloblattodea: Grylloblattidae) occupy climatically stable microhabitats within this region. Here we test critical thermal limits and supercooling points for five Grylloblatta populations from across a large geographic area, to examine whether the stable microhabitats of this group are associated with a narrow thermal niche and assess their capacity to tolerate cold conditions. Thermal limits are highly conserved in Grylloblatta, despite substantial genetic divergence among populations spanning 1500 m elevation and being separated by over 500 km. Further, Grylloblatta show exceptionally narrow thermal limits compared to other insect taxa with little capacity to improve cold tolerance via plasticity. In contrast, upper thermal limits were significantly depressed by cold acclimation. Grylloblatta maintain coordinated movement until they freeze, and they die upon freezing. Convergence of the critical thermal minima, supercooling point and lower lethal limits point to adaptation to a cold but, importantly, constant thermal environment. These physiological data provide an explanation for the high endemism and patchy distribution of Grylloblatta, which relies on subterranean retreats to accommodate narrow thermal limits. These retreats are currently buffered from temperature fluctuations by snow cover, and a declining snowpack thus places Grylloblatta at risk of exposure to temperatures beyond its tolerance capacity. Copyright © 2015 Elsevier Ltd. All rights
Freezing of gait: Promising avenues for future treatment.
Gilat, Moran; Lígia Silva de Lima, Ana; Bloem, Bastiaan R; Shine, James M; Nonnekes, Jorik; Lewis, Simon J G
2018-03-12
Freezing of gait is a devastating symptom of Parkinson's disease and other forms of parkinsonism. It poses a major burden on both patients and their families, as freezing often leads to falls, fall-related injuries and a loss of independence. Treating freezing of gait is difficult for a variety of reasons: it has a paroxysmal and unpredictable nature; a multifaceted pathophysiology, with an interplay between motor elements (disturbed stepping mechanisms) and non-motor elements (cognitive decline, anxiety); and a complex (and likely heterogeneous) underlying neural substrate, involving multiple failing neural networks. In recent years, advances in translational neuroscience have offered new insights into the pathophysiology underlying freezing. Furthermore, the mechanisms behind the effectiveness of available treatments (or lack thereof) are better understood. Driven by these concepts, researchers and clinicians have begun to improve currently available treatment options, and develop new and better treatment methods. Here, we evaluate the range of pharmacological (i.e. closed-looped approaches), surgical (i.e. multi-target and adaptive deep brain and spinal cord stimulation) and behavioural (i.e. biofeedback and cueing on demand) treatment options that are under development, and propose novel avenues that are likely to play a crucial role in the clinical management of freezing of gait in the near future. The outcomes of this review suggest that the successful future management of freezing of gait will require individualized treatments that can be implemented in an on-demand manner in response to imminent freezing. With this review we hope to guide much-needed advances in treating this devastating symptom of Parkinson's disease. Copyright © 2018 Elsevier Ltd. All rights reserved.
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.
7 CFR 58.638 - Freezing the mix.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 7 Agriculture 3 2013-01-01 2013-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.638 Freezing the mix. After the mix enters the freezer, it shall be frozen as rapidly as...
7 CFR 58.638 - Freezing the mix.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 7 Agriculture 3 2012-01-01 2012-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.638 Freezing the mix. After the mix enters the freezer, it shall be frozen as rapidly as...
7 CFR 58.638 - Freezing the mix.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 7 Agriculture 3 2014-01-01 2014-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards... Procedures § 58.638 Freezing the mix. After the mix enters the freezer, it shall be frozen as rapidly as...
2012-01-01
Background While it is recognised that depression is prevalent in Rheumatoid Arthritis (RA), recent studies have also highlighted significant levels of anxiety in RA patients. This study compared two commonly used scales, the Depression Anxiety and Stress Scale (DASS) and the Hospital Anxiety and Depression Scale (HADS), in relation to their measurement range and cut points to consider the relative prevalence of both constructs, and if prevalence rates may be due to scale-specific case definition. Methods Patients meeting the criteria for RA were recruited in Leeds, UK and Sydney, Australia and asked to complete a survey that included both scales. The data was analysed using the Rasch measurement model. Results A total of 169 RA patients were assessed, with a repeat subsample, resulting in 323 cases for analysis. Both scales met Rasch model expectations. Using the 'possible+probable' cut point from the HADS, 58.3% had neither anxiety nor depression; 13.5% had anxiety only; 6.4% depression only and 21.8% had both 'possible+probable' anxiety and depression. Cut points for depression were comparable across the two scales while a lower cut point for anxiety in the DASS was required to equate prevalence. Conclusions This study provides further support for high prevalence of depression and anxiety in RA. It also shows that while these two scales provide a good indication of possible depression and anxiety, the estimates of prevalence so derived could vary, particularly for anxiety. These findings are discussed in terms of comparisons across studies and selection of scales for clinical use. PMID:22269280
Covic, Tanya; Cumming, Steven R; Pallant, Julie F; Manolios, Nick; Emery, Paul; Conaghan, Philip G; Tennant, Alan
2012-01-24
While it is recognised that depression is prevalent in Rheumatoid Arthritis (RA), recent studies have also highlighted significant levels of anxiety in RA patients. This study compared two commonly used scales, the Depression Anxiety and Stress Scale (DASS) and the Hospital Anxiety and Depression Scale (HADS), in relation to their measurement range and cut points to consider the relative prevalence of both constructs, and if prevalence rates may be due to scale-specific case definition. Patients meeting the criteria for RA were recruited in Leeds, UK and Sydney, Australia and asked to complete a survey that included both scales. The data was analysed using the Rasch measurement model. A total of 169 RA patients were assessed, with a repeat subsample, resulting in 323 cases for analysis. Both scales met Rasch model expectations. Using the 'possible+probable' cut point from the HADS, 58.3% had neither anxiety nor depression; 13.5% had anxiety only; 6.4% depression only and 21.8% had both 'possible+probable' anxiety and depression. Cut points for depression were comparable across the two scales while a lower cut point for anxiety in the DASS was required to equate prevalence. This study provides further support for high prevalence of depression and anxiety in RA. It also shows that while these two scales provide a good indication of possible depression and anxiety, the estimates of prevalence so derived could vary, particularly for anxiety. These findings are discussed in terms of comparisons across studies and selection of scales for clinical use.
23 CFR 658.23 - LCV freeze; cargo-carrying unit freeze.
Code of Federal Regulations, 2010 CFR
2010-04-01
... safety purposes and road construction, a State may make minor adjustments of a temporary and emergency... decision is reached that minor adjustments made by a State are not legitimately attributable to road or bridge construction or safety, the FHWA will inform the State, and the original conditions of the freeze...
Embolism Formation during Freezing in the Wood of Picea abies1
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. PMID:17041033
Experimental analysis and modeling of ultrasound assisted freezing of potato spheres.
Kiani, Hossein; Zhang, Zhihang; Sun, Da-Wen
2015-09-01
In recent years, innovative methods such as ultrasound assisted freezing have been developed in order to improve the freezing process. During freezing of foods, accurate prediction of the temperature distribution, phase ratios, and process time is very important. In the present study, ultrasound assisted immersion freezing process (in 1:1 ethylene glycol-water solution at 253.15K) of potato spheres (0.02 m diameter) was evaluated using experimental, numerical and analytical approaches. Ultrasound (25 kHz, 890 W m(-2)) was irradiated for different duty cycles (DCs=0-100%). A finite volume based enthalpy method was used in the numerical model, based on which temperature and liquid fraction profiles were simulated by a program developed using OpenFOAM® CFD software. An analytical technique was also employed to calculate freezing times. The results showed that ultrasound irradiation could decrease the characteristic freezing time of potatoes. Since ultrasound irradiation increased the heat transfer coefficient but simultaneously generated heat at the surface of the samples, an optimum DC was needed for the shortest freezing time which occurred in the range of 30-70% DC. DCs higher than 70% increased the freezing time. DCs lower than 30% did not provide significant effects on the freezing time compared to the control sample. The numerical model predicted the characteristic freezing time in accordance with the experimental results. In addition, analytical calculation of characteristic freezing time exhibited qualitative agreement with the experimental results. As the numerical simulations provided profiles of temperature and water fraction within potatoes frozen with or without ultrasound, the models can be used to study and control different operation situations, and to improve the understanding of the freezing process. Copyright © 2015 Elsevier B.V. All rights reserved.
Heterogeneous freezing of super cooled water droplets in micrometre range- freezing on a chip
NASA Astrophysics Data System (ADS)
Häusler, Thomas; Witek, Lorenz; Felgitsch, Laura; Hitzenberger, Regina; Grothe, Hinrich
2017-04-01
A new setup to analyse the freezing behaviour of ice nucleation particles (INPs) dispersed in aqueous droplets has been developed with the aim to analyse ensembles of droplets with sizes in the micrometre range, in which INPs are immersed. Major disadvantages of conventional drop-freezing experiments like varying drop sizes or interactions between the water- oil mixture and the INP, were solved by introducing a unique freezing- chip consisting of an etched and sputtered 15x15x1 mm gold-plated silicon or pure gold film (Pummer et al., 2012; Zolles et al., 2015). Using this chip, isolated micrometre-sized droplets can be generated with sizes similar to droplets in real world clouds. The experimental set-up for drop-freezing experiments was revised and improved by establishing automated process control and image evaluation. We were able to show the efficiency and accuracy of our setup by comparing measured freezing temperatures of different INPs (Snomax®, K- feldspar, birch pollen (Betula pendula) washing water, juniper pollen suspension (Juniperus communis) and ultrapure water) with already published results (Atkinson et al., 2013; Augustin et al., 2013; Pruppacher and Klett, 1997; Pummer et al., 2012; Wex et al., 2015; Zolles et al., 2015). Comparison of our measurements with literature data show the important impact of droplet size, INP concentration and number of active sites on the T50 values. Here, the new set-up exhibits its strength in reproducibility and accuracy which is due to the defined and isolated droplets. Finally, it opens a temperature window down to -37˚ C for freezing experiments which was not accessible with former traditional approaches .Atkinson, J. D., Murray, B. J., Woodhouse, M. T., Whale, T. F., Baustian, K. J., Carslaw, K. S., Dobbie, S., O'Sullivan, D., and Malkin, T. L.: The importance of feldspar for ice nucleation by mineral dust in mixed-phase clouds (vol 498, pg 355, 2013), Nature, 500, 491-491, 2013. Augustin, S., Wex, H
Preparation of freezing quantum state for quantum coherence
NASA Astrophysics Data System (ADS)
Yang, Lian-Wu; Man, Zhong-Xiao; Zhang, Ying-Jie; Han, Feng; Du, Shao-jiang; Xia, Yun-Jie
2018-06-01
We provide a method to prepare the freezing quantum state for quantum coherence via unitary operations. The initial product state consists of the control qubit and target qubit; when it satisfies certain conditions, the initial product state converts into the particular Bell diagonal state under the unitary operations, which have the property of freezing of quantum coherence under quantum channels. We calculate the frozen quantum coherence and corresponding quantum correlations, and find that the quantities are determined by the control qubit only when the freezing phenomena occur.
Woods, P S; Ledbetter, M C; Tempel, N
1991-06-01
We describe methods for freezing and drying EDTA-expanded, fixed metaphase chromosomes and nuclei, attached to grids as whole-mounts, for transmission electron microscopy. These methods use a special apparatus that is simple to construct. While separate freezers and dryers are commercially available, one for freezing blocks of tissue by slamming them against a cold metal surface, and the other for vacuum drying the frozen tissue, our apparatus is designed for gentler, cryogenic liquid plunge freezing and drying, sequentially, in the same apparatus, thus avoiding any compression or damage to the specimen. Use of a cryoprotectant is not essential; however, good results are obtained more often when 20% ethanol is used. Freezing is accomplished by rapid propulsion of the grid, with specimens attached, into slushy N2 (-210 degrees C) within the drying chamber; drying is automatic, by either sublimation under vacuum or by solvent substitution using absolute ethanol followed by acetone, which, in turn, is removed with a critical-point dryer. The apparatus offers a means of drying chromosomes and nuclei in an expanded state, and avoids the shrinkage of these structures that occurs during stepwise passage through increasing concentrations of ethanol or acetone.
Nature and morphology of fumed oxides and features of interfacial phenomena
NASA Astrophysics Data System (ADS)
Gun'ko, V. M.; Zarko, V. I.; Goncharuk, O. V.; Matkovsky, A. K.; Remez, O. S.; Skubiszewska-Zięba, J.; Wojcik, G.; Walusiak, B.; Blitz, J. P.
2016-03-01
Individual and complex fumed nanooxides were studied using high-resolution transmission electron microscopy, X-ray diffraction, ultraviolet-visible (UV-vis) spectroscopy, differential scanning calorimetry, nuclear magnetic resonance spectroscopy, adsorption, desorption (evaporation), and quantum chemical methods. For mixed nanooxides in contrast to simple and small nanoparticles of individual silica or titania, complex core-shell nanoparticles (50-200 nm in size) with titania or alumina cores and silica or alumina shells can be destroyed under high-pressure cryogelation (HPCG), mechnochemical activation (MCA) that also affect the structure of aggregates of nanoparticles and agglomerates of aggregates becoming more compacted. This is accompanied by changes in color from white to beige of different tints and changes in the UV-vis spectra in the 300-600 nm range, as well as changes in crystalline structure of alumina. Any treatment of 'soft' nanooxides affects the interfacial behavior of polar and nonpolar adsorbates. For some of them, the hysteresis loops become strongly open. Rearrangement of secondary particles affects the freezing-melting point depression. Clusterization of adsorbates bound in pores causes diminution of heat effects during phase transition (freezing, fusion). Freezing point depression and increasing melting point cause significant hysteresis freezing-melting effects for adsorbates bound to oxide nanoparticles. The study shows that complex nanooxides can be more sensitive to external actions than simple nanooxides such as silica.
Betrus, P A; Elmore, S K; Woods, N F; Hamilton, P A
1995-01-01
As Western society increases in complexity and becomes more reliant on technology, women who thrive as integrators in interactional modes will face new dilemmas. Many women will view these changes as challenges, but for many other women, who view these changes as threats, the response will be depression. We lay a foundation to an understanding of depression in women, evaluating the current concept of depression and pointing out its limitations. We then review the traditional theories of women's increased vulnerability to depressive disorders, which have failed to explain adequately this phenomenon. A more recent theory of women's depression, based on the self-in-relation theory of women's development, is offered as an alternative.
Isochoric and isobaric freezing of fish muscle
DOE Office of Scientific and Technical Information (OSTI.GOV)
Năstase, Gabriel; Department of Building Services, University of Transilvania, Braşov, Braşov, 500152; Lyu, Chenang
We have recently shown that, a living organism, which succumbs to freezing to −4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive freezing to −4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the freezing caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric freezing is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, andmore » the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to −5 °C in an isobaric system and c) fresh muscle frozen to −5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric freezing. In contrast, the muscle tissue frozen to −5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric freezing there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact. - Highlights: • Preservation of fish muscle at, subfreezing temperatures, in an isochoric system, is demonstrated. • Experiments were performed to an average pressure of 41.3 MPa and temperatures of −5 °C. • Isochoric subfreezing temperature is a new preservation method that does not require the.use of cryoprotectants. • No cellular dehydration and therefore the morphology of the frozen tissue remains intact.« less
A new approach for freezing of aqueous solutions under active control of the nucleation temperature.
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.
Freezing temperature protection admixture for Portland cement concrete
DOT National Transportation Integrated Search
1996-10-01
A number of experimental admixtures were compared to Pozzutec 20 admixture for their ability to protect fresh concrete from freezing and for increasing the rate of cement hydration at below-freezing temperatures. The commercial accelerator and low-te...
Development of freeze dried vegetables
NASA Technical Reports Server (NTRS)
Larson, R. W.
1970-01-01
The development of freeze dried vegetables to be used in the Apollo food system is discussed. After the initial selection and screening of vegetables, several types of freeze dried vegetables were prepared in small batches. From these small batches, two vegetables were judged satisfactory for further testing and evaluation. These vegetables, mashed potatoes and asparagus, were subjected to storage at 100 deg plus or minus 5 F. for two weeks and then taste tested. The vegetables were also tested to determine if they complied with the microbiological requirements for Apollo food. The space food prototype production guide for the vegetables is submitted.
Research on strength attenuation law of concrete in freezing - thawing environment
NASA Astrophysics Data System (ADS)
Xiao, qianhui; Cao, zhiyuan; Li, qiang
2018-03-01
By rapid freezing and thawing method, the experiments of concrete have been 300 freeze-thaw cycles specimens in the water. The cubic compression strength value under different freeze-thaw cycles was measured. By analyzing the test results, the water-binder ratio of the concrete under freeze-thaw environments, fly ash and air entraining agent is selected dosage recommendations. The exponential attenuation prediction model and life prediction model of compression strength of concrete under freezing-thawing cycles considering the factors of water-binder ratio, fly ash content and air-entraining agent dosage were established. The model provides the basis for predicting the durability life of concrete under freezing-thawing environment. It also provides experimental basis and references for further research on concrete structures with antifreeze requirements.
Universal pion freeze-out in heavy-ion collisions.
Adamová, D; Agakichiev, G; Appelshäuser, H; Belaga, V; Braun-Munzinger, P; Castillo, A; Cherlin, A; Damjanović, S; Dietel, T; Dietrich, L; Drees, A; Esumi, S I; Filimonov, K; Fomenko, K; Fraenkel, Z; Garabatos, C; Glässel, P; Hering, G; Holeczek, J; Kushpil, V; Lenkeit, B; Ludolphs, W; Maas, A; Marín, A; Milosević, J; Milov, A; Miśkowiec, D; Panebrattsev, Yu; Petchenova, O; Petrácek, V; Pfeiffer, A; Rak, J; Ravinovich, I; Rehak, P; Sako, H; Schmitz, W; Schukraft, J; Sedykh, S; Shimansky, S; Slívová, J; Specht, H J; Stachel, J; Sumbera, M; Tilsner, H; Tserruya, I; Wessels, J P; Wienold, T; Windelband, B; Wurm, J P; Xie, W; Yurevich, S; Yurevich, V
2003-01-17
Based on an evaluation of data on pion interferometry and on particle yields at midrapidity, we propose a universal condition for thermal freeze-out of pions in heavy-ion collisions. We show that freeze-out occurs when the mean free path of pions lambda(f) reaches a value of about 1 fm, which is much smaller than the spatial extent of the system at freeze-out. This critical mean free path is independent of the centrality of the collision and beam energy from the Alternating Gradient Synchrotron to the Relativistic Heavy Ion Collider.
Water vapor movement in freezing aggregate base materials.
DOT National Transportation Integrated Search
2014-06-01
The objectives of this research were to 1) measure the extent to which water vapor movement results in : water accumulation in freezing base materials; 2) evaluate the effect of soil stabilization on water vapor movement : in freezing base materials;...
St. Lawrence River Freeze-Up Forecast Procedure.
ERIC Educational Resources Information Center
Assel, R. A.
A standard operating procedure (SOP) is presented for calculating the date of freeze-up on the St. Lawrence River at Massena, N.Y. The SOP is based on two empirical temperature decline equations developed for Kingston, Ontario, and Massena, N.Y., respectively. Input data needed to forecast freeze-up consist of the forecast December flow rate and…
A freeze-stable formulation for DTwP and DTaP vaccines.
Xue, Honggang; Yang, Bangling; Kristensen, Debra D; Chen, Dexiang
2014-01-01
Inadvertent vaccine freezing often occurs in the cold chain and may cause damage to freeze‑sensitive vaccines. Liquid vaccines that contain aluminum salt adjuvants are particularly vulnerable. Polyol cryoprotective excipients have been shown to prevent freeze damage to hepatitis B vaccine. In this study, we examined the freeze-protective effect of propylene glycol on diphtheria-tetanus-pertussis-whole-cell (DTwP) and acellular (DTaP) vaccines. Pilot lots of DTwP and DTaP formulated with 7.5% propylene glycol underwent 3 freeze-thaw treatments. The addition of propylene glycol had no impact on pH, particle size distribution, or potency of the vaccines prior to freeze-thaw treatment; the only change noted was an increase in osmolality. The potencies and the physical properties of the vaccines containing cryoprotectant were maintained after freeze-thawing and for 3 months in accelerated stability studies. The results from this study indicate that formulating vaccines with propylene glycol can protect diphtheria-tetanus-pertussis vaccines against freeze damages.
The tolerance of the field slug Deroceras reticulatum to freezing temperatures.
Cook, R T
2004-01-01
Cold hardiness of ectotherms has been widely studied in arthropods, but there is a more limited literature on the survival of molluscs at low temperatures. A number of intertidal species have been examined in detail, but terrestrial molluscs have largely been overlooked until recently. This paper reports results of laboratory experiments to evaluate the cold hardiness of the terrestrial slug, Deroceras reticulatum. The mean supercooling point (SCP) rose from -4.2 degree C in summer to -3.6 degree C in winter. The SCP that caused 50 percent mortality (LSCP50) remained constant at -4.7 to -4.8 degree C in both seasons, but slugs were able to survive the frozen state for longer in winter (LD50 of 31.8 minutes compared with 17.0 minutes in summer). Slug survival at freezing temperatures was prolonged to at least five hours when placed on a moist, absorbent substrate. D. reticulatum exhibits partial freeze tolerance, with an increased survival in winter. The results are discussed in relation to the natural environment of slugs.
Comtet, Jean; Niguès, Antoine; Kaiser, Vojtech; Coasne, Benoit; Bocquet, Lydéric; Siria, Alessandro
2017-01-01
Room temperature Ionic liquids (RTIL) are new materials with fundamental importance for energy storage and active lubrication. They are unsual liquids, which challenge the classical frameworks of electrolytes, whose behavior at electrified interfaces remains elusive with exotic responses relevant to their electrochemical activity. By means of tuning fork based AFM nanorheological measurements, we explore here the properties of confined RTIL, unveiling a dramatic change of the RTIL towards a solid-like phase below a threshold thickness, pointing to capillary freezing in confinement. This threshold is related to the metallic nature of the confining materials, with more metallic surfaces facilitating freezing. This is interpreted in terms of the shift of freezing transition, taking into account the influence of the electronic screening on RTIL wetting of the confining surfaces. Our findings provide fresh views on the properties of confined RTIL with implications for their properties inside nanoporous metallic structures and suggests applications to tune nanoscale lubrication with phase-changing RTIL, by varying the nature and patterning of the substrate, and application of active polarisation. PMID:28346432
NASA Astrophysics Data System (ADS)
Comtet, Jean; Niguès, Antoine; Kaiser, Vojtech; Coasne, Benoit; Bocquet, Lydéric; Siria, Alessandro
2017-06-01
Room-temperature ionic liquids (RTILs) are new materials with fundamental importance for energy storage and active lubrication. They are unusual liquids, which challenge the classical frameworks of electrolytes, whose behaviour at electrified interfaces remains elusive, with exotic responses relevant to their electrochemical activity. Using tuning-fork-based atomic force microscope nanorheological measurements, we explore here the properties of confined RTILs, unveiling a dramatic change of the RTIL towards a solid-like phase below a threshold thickness, pointing to capillary freezing in confinement. This threshold is related to the metallic nature of the confining materials, with more metallic surfaces facilitating freezing. This behaviour is interpreted in terms of the shift of the freezing transition, taking into account the influence of the electronic screening on RTIL wetting of the confining surfaces. Our findings provide fresh views on the properties of confined RTIL with implications for their properties inside nanoporous metallic structures, and suggests applications to tune nanoscale lubrication with phase-changing RTILs, by varying the nature and patterning of the substrate, and application of active polarization.
Comtet, Jean; Niguès, Antoine; Kaiser, Vojtech; Coasne, Benoit; Bocquet, Lydéric; Siria, Alessandro
2017-06-01
Room-temperature ionic liquids (RTILs) are new materials with fundamental importance for energy storage and active lubrication. They are unusual liquids, which challenge the classical frameworks of electrolytes, whose behaviour at electrified interfaces remains elusive, with exotic responses relevant to their electrochemical activity. Using tuning-fork-based atomic force microscope nanorheological measurements, we explore here the properties of confined RTILs, unveiling a dramatic change of the RTIL towards a solid-like phase below a threshold thickness, pointing to capillary freezing in confinement. This threshold is related to the metallic nature of the confining materials, with more metallic surfaces facilitating freezing. This behaviour is interpreted in terms of the shift of the freezing transition, taking into account the influence of the electronic screening on RTIL wetting of the confining surfaces. Our findings provide fresh views on the properties of confined RTIL with implications for their properties inside nanoporous metallic structures, and suggests applications to tune nanoscale lubrication with phase-changing RTILs, by varying the nature and patterning of the substrate, and application of active polarization.
Involvement of Two Specific Causes of Cell Mortality in Freeze-Thaw Cycles with Freezing to −196°C
Dumont, Frédéric; Marechal, Pierre-André; Gervais, Patrick
2006-01-01
The purpose of this study was to examine cell viability after freezing. Two distinct ranges of temperature were identified as corresponding to stages at which yeast cell mortality occurred during freezing to −196°C. The upper temperature range was related to the temperature of crystallization of the medium, which was dependent on the solute concentration; in this range mortality was prevented by high solute concentrations, and the proportion of the medium in the vitreous state was greater than the proportion in the crystallized state. The lower temperature range was related to recrystallization that occurred during thawing. Mortality in this temperature range was increased by a high cooling rate and/or high solute concentration in the freezing medium and a low temperature (less than −70°C). However, a high rate of thawing prevented yeast mortality in this lower temperature range. Overall, it was found that cell viability could be conserved better under freezing conditions by increasing the osmotic pressure of the medium and by using an increased warming rate. PMID:16461684
Perspective: Surface freezing in water: A nexus of experiments and simulations
NASA Astrophysics Data System (ADS)
Haji-Akbari, Amir; Debenedetti, Pablo G.
2017-08-01
Surface freezing is a phenomenon in which crystallization is enhanced at a vapor-liquid interface. In some systems, such as n-alkanes, this enhancement is dramatic and results in the formation of a crystalline layer at the free interface even at temperatures slightly above the equilibrium bulk freezing temperature. There are, however, systems in which the enhancement is purely kinetic and only involves faster nucleation at or near the interface. The first, thermodynamic, type of surface freezing is easier to confirm in experiments, requiring only the verification of the existence of crystalline order at the interface. The second, kinetic, type of surface freezing is far more difficult to prove experimentally. One material that is suspected of undergoing the second type of surface freezing is liquid water. Despite strong indications that the freezing of liquid water is kinetically enhanced at vapor-liquid interfaces, the findings are far from conclusive, and the topic remains controversial. In this perspective, we present a simple thermodynamic framework to understand conceptually and distinguish these two types of surface freezing. We then briefly survey fifteen years of experimental and computational work aimed at elucidating the surface freezing conundrum in water.
NASA Astrophysics Data System (ADS)
Soare, Richard; Conway, Susan; Gallagher, Colman; Dohm, James; Clifford, Stephen M.; Williams, Jean-pierre
2016-10-01
We report the spatial and possible genetic-relationship at the mid-latitudes of Utopia Planitia (45-500N 115-1200E), Mars, of: (a) metre to decametre deep, rimless, tiered depressions; terrain that exhibits (b) (clastically) sorted and (c) unsorted (small-sized) polygons; and, (d) a very youthful, ice-rich mantle. We show that these individual landscape features are separated stratigraphically, this being presented to the Mars community for the first time, and suggest that the stratigraphical separation of these features could be the result of boundary conditions and formation processes that have varied much more widely than has been thought hitherto. In cold-climate and non-glacial regions such as the Yamal Peninsula of eastern Russia and the Tuktoyaktuk Coastlands of northern Canada, landscape assemblages comprised of similar features are referenced as "ice complexes" and are indicative of periglacialism on two fronts: first, the presence of "ice-rich" permafrost or permafrost comprised of "excess ice", i.e. "permafrost" whose pore space is exceeded by the "water ice" within that body of sediment; and, second, antecedently or currently active freeze-thaw cycling, minimally, to the full depth of the "ice-complex" depressions. In the Dry Valleys of the Antarctic, where the atmospheric aridity and cold-temperatures approach those of Mars, ice-vapour diffusion and adsorption cycles are cited as the means by which the near-surface, permafrost, i.e. ≤1m deep, has become ice-cemented. However, the metre to decametre depths of the "ice-complex" depressions on Earth and the morphologically-similar ones on Mars lie beyond the vertical reach of the Antarctic diffusion and adsorption cycles, both empirically and theoretically. By deduction, this points to the freeze-thaw cycling of water to depth, fostered either by exogenic or endogenic means, perhaps playing a more important role in the formation of the possible Martian "ice complexes" than might be expected were
New aspects of boar semen freezing strategies.
Grossfeld, R; Sieg, B; Struckmann, C; Frenzel, A; Maxwell, W M C; Rath, D
2008-11-01
Although cryopreserved boar semen has been available since 1975, a major breakthrough in commercial application has not yet occurred. There is ongoing research to improve sperm survival after thawing, to limit the damage occurring to spermatozoa during freezing, and to further minimize the number of spermatozoa needed to establish a pregnancy. Boar spermatozoa are exposed to lipid peroxidation during freezing and thawing, which causes damage to the sperm membranes and impairs energy metabolism. The addition of antioxidants or chelating agents (e.g. catalase, vitamin E, glutathione, butylated hydroxytoluene or superoxide dismutase) to the still standard egg-yolk based cooling and freezing media for boar semen, effectively prevented this damage. In general, final glycerol concentrations of 2-3% in the freezing media, cooling rates of -30 to -50 degrees C/min, and thawing rates of 1200-1800 degrees C/min resulted in the best sperm survival. However, cooling and thawing rates individually optimized for sub-standard freezing boars have substantially improved their sperm quality after cryopreservation. With deep intrauterine insemination, the sperm dose has been decreased from 6 to 1x10(9) spermatozoa without compromising farrowing rate or litter size. Minimizing insemination-to-ovulation intervals, based either on estimated or determined ovulation, have also improved the fertility after AI with cryopreserved boar semen. With this combination of different approaches, acceptable fertility with cryopreserved boar semen can be achieved, facilitating the use of cryopreserved boar semen in routine AI programs.
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.
Freeze-drying process monitoring using a cold plasma ionization device.
Mayeresse, Y; Veillon, R; Sibille, P H; Nomine, C
2007-01-01
A cold plasma ionization device has been designed to monitor freeze-drying processes in situ by monitoring lyophilization chamber moisture content. This plasma device, which consists of a probe that can be mounted directly on the lyophilization chamber, depends upon the ionization of nitrogen and water molecules using a radiofrequency generator and spectrometric signal collection. The study performed on this probe shows that it is steam sterilizable, simple to integrate, reproducible, and sensitive. The limitations include suitable positioning in the lyophilization chamber, calibration, and signal integration. Sensitivity was evaluated in relation to the quantity of vials and the probe positioning, and correlation with existing methods, such as microbalance, was established. These tests verified signal reproducibility through three freeze-drying cycles. Scaling-up studies demonstrated a similar product signature for the same product using pilot-scale and larger-scale equipment. On an industrial scale, the method efficiently monitored the freeze-drying cycle, but in a larger industrial freeze-dryer the signal was slightly modified. This was mainly due to the positioning of the plasma device, in relation to the vapor flow pathway, which is not necessarily homogeneous within the freeze-drying chamber. The plasma tool is a relevant method for monitoring freeze-drying processes and may in the future allow the verification of current thermodynamic freeze-drying models. This plasma technique may ultimately represent a process analytical technology (PAT) approach for the freeze-drying process.
The effect of low temperature on Antarctic endolithic green algae
NASA Technical Reports Server (NTRS)
Meyer, M. A.; Morris, G. J.; Friedmann, E. I.
1988-01-01
Laboratory experiments show that undercooling to about -5 degrees C occurs in colonized Beacon sandstones of the Ross Desert, Antarctica. High-frequency temperature oscillations between 5 degrees C and -5 degrees C or -10 degrees C (which occur in nature on the rock surface) did not damage Hemichloris antarctica. In a cryomicroscope, H. antarctica appeared to be undamaged after slow or rapid cooling to -50 degrees C. 14CO2 incorporation after freezing to -20 degrees C was unaffected in H. antarctica or in Trebouxia sp. but slightly depressed in Stichococcus sp. (isolated from a less extreme Antarctic habitat). These results suggest that the freezing regime in the Antarctic desert is not injurious to endolithic algae. It is likely that the freezing-point depression inside the rock makes available liquid water for metabolic activity at subzero temperatures. Freezing may occur more frequently on the rock surface and contribute to the abiotic nature of the surface.
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…
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.
New Processes for Freeze-Drying in Dual-Chamber Systems.
Werk, T; Ludwig, I S; Luemkemann, J; Huwyler, J; Mahler, H-C; Haeuser, C R; Hafner, M
2016-01-01
Dual-chamber systems can offer self-administration and home care use for lyophilized biologics. Only a few products have been launched in dual-chamber systems so far-presumably due to dual-chamber systems' complex and costly drug product manufacturing process. Within this paper, two improved processes (both based on tray filling technology) for freeze-drying pharmaceuticals in dual-chamber systems are described. Challenges with regards to heat transfer were tackled by (1) performing the freeze-drying step in a needle-down orientation in combination with an aluminum block, or (2) freeze-drying the drug product "externally" in a metal cartridge with subsequent filling of the lyophilized cake into the dual-chamber system. Metal-mediated heat transfer was shown to be efficient in both cases and batch (unit-to-unit) homogeneity with regards to sublimation rate was increased. It was difficult to influence ice crystal size using different methods when in use with an aluminum block due to its heat capacity. Using such a metal carrier implies a large heat capacity leading to relatively small ice crystals. Compared to the established process, drying times were reduced by half using the new processes. The drying time was, however, longer for syringes compared to vials due to the syringe design (long and slim). The differences in drying times were less pronounced for aggressive drying cycles. The proposed processes may help to considerably decrease investment costs into dual-chamber system fill-finish equipment. Dual-chamber syringes offer self-administration and home care use for freeze-dried pharmaceuticals. Only a few products have been launched in dual-chamber syringes so far-presumably due to their complex and costly drug product manufacturing process. In this paper two improved processes for freeze-drying pharmaceuticals in dual-chamber syringes are described. The major challenge of freeze-drying is to transfer heat through a vacuum. The proposed processes cope with this
Alvarez-Rodríguez, Manuel; Alvarez, Mercedes; López-Urueña, Elena; Martínez-Rodriguez, Carmen; Borragan, Santiago; Anel-López, Luis; de Paz, Paulino; Anel, Luis
2013-12-01
The use of sexed spermatozoa has great potential to captive population management in endangered wildlife. The problem is that the sex-sorting facility is a long distance from the semen collection place and to overcome this difficulty two freeze-thaw cycles may be necessary. In this study, effects of refreezing on brown bear electroejaculated spermatozoa were analyzed. We carried out two experiments: (1) to assess the effects of the two freezing-thawing cycles on sperm quality and to analyze three different elapsed times between freezing-thawing cycles (30, 90 and 180 min), and (2) to analyze the use of PureSperm between freezing-thawing cycles to select a more motile and viable sperm subpopulation which better survived first freezing. The motility, viability and undamaged acrosomes were significantly reduced after the second thawing respect to first thawing into each elapsed time group, but the elapsed times did not significantly affect the viability and acrosome status although motility was damaged. Our results with the PureSperm gradient showed higher values of viability in freezability of select sample (pellet) respect to the rest of the groups and it also showed a significant decrease in the number of acrosome damaged. In summary, the double freezing of bear semen selected by gradient centrifugation is qualitatively efficient, and thus could be useful to carry out a sex-sorting of frozen-thawed bear spermatozoa before to send the cryopreserved sample to a biobank. Given the low recovery of spermatozoa after applying a selection gradient, further studies will be needed to increase the recovery rate without damaging of the cell quality. Copyright © 2013 Elsevier Inc. All rights reserved.
Why are hyperactive ice-binding-proteins so active?
NASA Astrophysics Data System (ADS)
Braslavsky, Ido; Celik, Yeliz; Pertaya, Natalya; Eun Choi, Young; Bar, Maya; Davies, Peter L.
2008-03-01
Ice binding proteins (IBPs), also called `antifreeze proteins' or `ice structuring proteins', are a class of proteins that protect organisms from freezing injury. These proteins have many applications in medicine and agriculture, and as a platform for future biotechnology applications. One of the interesting questions in this field focuses on the hyperactivity of some IBPs. Ice binding proteins can be classified in two groups: moderate ones that can depress the freezing point up to ˜1.0 ^oC and hyperactive ones that can depress the freezing point several-fold further even at lower concentrations. It has been suggested that the hyperactivity of IBPs stem from the fact that they block growth out of specific ice surfaces, more specifically the basal planes of ice. Here we show experimental results based on fluorescence microscopy, highlighting the differences between moderate IBPs and hyperactive IBPs. These include direct evidence for basal plane affinity of hyperactive IBPs, the effects of IBPs on growth-melt behavior of ice and the dynamics of their interaction with ice.
Physicochemical characterization of commercial freeze-dried snake antivenoms.
Herrera, María; Solano, Daniela; Gómez, Aarón; Villalta, Mauren; Vargas, Mariángela; Sánchez, Andrés; Gutiérrez, José María; León, Guillermo
2017-02-01
Freeze-drying is a process used to improve the stability of pharmaceutical proteins, including snake antivenoms. This additional step confers these with a higher stability in comparison to liquid formulations, especially in tropical regions where high temperatures could affect the activity of immunoglobulins. Currently, the knowledge about freeze-drying process conditions for snake antivenoms is very limited. Some of the scarce scientific works on this subject reported reconstitution times up to 90 min for these preparations, which could imply a delay in the beginning of the antivenom therapy at the clinical setting. Therefore there is a reasonable concern about whether freeze-dried antivenoms exhibit the desired attributes for solid pharmaceutical proteins. In this work, a physicochemical characterization of seven commercial freeze-dried snake antivenoms was performed based on tests recommended by the World Health Organization (WHO). No significant differences were observed between the products regarding macroscopic appearance of the solid cakes, reconstitution times, residual humidity and monomers content. On the other hand, total protein concentration, turbidity and electrophoretic profile were different among samples. Microscopic analysis by scanning electron microscopy showed no collapsed structure and, instead, most of the samples showed a characteristic protein morphology composed of smooth plates and channels. All the parameters tested in this study were according to literature recommendations and evidenced that, in spite of slight variations found for some products, formulation and freeze-drying conditions chosen by manufacturers are adequate to prevent aggregation and generate, in physicochemical terms, freeze-dried antivenoms of acceptable quality. Copyright © 2016 Elsevier Ltd. All rights reserved.
Mutagenic effect of freezing on nuclear DNA of Saccharomyces cerevisiae.
Todorova, T; Pesheva, M; Stamenova, R; Dimitrov, M; Venkov, P
2012-05-01
Although fragmentation of DNA has been observed in cells undergoing freezing procedures, a mutagenic effect of sub-zero temperature treatment has not been proved by induction and isolation of mutants in nuclear DNA (nDNA). In this communication we supply evidence for mutagenicity of freezing on nDNA of Saccharomyces cerevisiae cells. In the absence of cryoprotectors, cooling for 2 h at +4°C and freezing for 1 h at -10°C and 16 h at -20°C, with a cooling rate of 3°C/min, resulted in induction of frame-shift and reverse mutations in microsatellite and coding regions of nDNA. The sub-zero temperature exposure also has a strong recombinogenic effect, evidenced by induction of gene-conversion and crossing-over events. Freezing induces mutations and enhances recombination with a frequency equal to or higher than that of methylmethanesulphonate at comparable survival rates. The signals for the appearance of nDNA lesions induced by freezing are detected and transduced by the DNA damage pathway. Extracellular cryoprotectors did not prevent the mutagenic effect of freezing, while accumulation of trehalose inside cells reduced nDNA cryodamage. Freezing of cells is accompanied by generation of high ROS levels, and the oxidative stress raised during the freeze-thaw process is the most likely reason for the DNA damaging effect. Experiments with mitochondrial rho⁻ mutants or scavengers of ROS indicated that mutagenic and recombinogenic effects of sub-zero temperatures can be decreased but not eliminated by reduction of ROS level. The complete protection against cryodamage in nDNA required simultaneous usage of intracellular cryoprotector and ROS scavenger during the freeze-thaw process. Copyright © 2012 John Wiley & Sons, Ltd.
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 treatment...
Brouckaert, Davinia; De Meyer, Laurens; Vanbillemont, Brecht; Van Bockstal, Pieter-Jan; Lammens, Joris; Mortier, Séverine; Corver, Jos; Vervaet, Chris; Nopens, Ingmar; De Beer, Thomas
2018-04-03
Near-infrared chemical imaging (NIR-CI) is an emerging tool for process monitoring because it combines the chemical selectivity of vibrational spectroscopy with spatial information. Whereas traditional near-infrared spectroscopy is an attractive technique for water content determination and solid-state investigation of lyophilized products, chemical imaging opens up possibilities for assessing the homogeneity of these critical quality attributes (CQAs) throughout the entire product. In this contribution, we aim to evaluate NIR-CI as a process analytical technology (PAT) tool for at-line inspection of continuously freeze-dried pharmaceutical unit doses based on spin freezing. The chemical images of freeze-dried mannitol samples were resolved via multivariate curve resolution, allowing us to visualize the distribution of mannitol solid forms throughout the entire cake. Second, a mannitol-sucrose formulation was lyophilized with variable drying times for inducing changes in water content. Analyzing the corresponding chemical images via principal component analysis, vial-to-vial variations as well as within-vial inhomogeneity in water content could be detected. Furthermore, a partial least-squares regression model was constructed for quantifying the water content in each pixel of the chemical images. It was hence concluded that NIR-CI is inherently a most promising PAT tool for continuously monitoring freeze-dried samples. Although some practicalities are still to be solved, this analytical technique could be applied in-line for CQA evaluation and for detecting the drying end point.
NASA Astrophysics Data System (ADS)
Baker, Michael J.; Breitbach, Moritz; Kopp, Joachim; Mittnacht, Lukas
2018-03-01
The cosmological abundance of dark matter can be significantly influenced by the temperature dependence of particle masses and vacuum expectation values. We illustrate this point in three simple freeze-in models. The first one, which we call kinematically induced freeze-in, is based on the observation that the effective mass of a scalar temporarily becomes very small as the scalar potential undergoes a second order phase transition. This opens dark matter production channels that are otherwise forbidden. The second model we consider, dubbed vev-induced freeze-in, is a fermionic Higgs portal scenario. Its scalar sector is augmented compared to the Standard Model by an additional scalar singlet, S, which couples to dark matter and temporarily acquires a vacuum expectation value (a two-step phase transition or "vev flip-flop"). While < S> ≠ 0, the modified coupling structure in the scalar sector implies that dark matter production is significantly enhanced compared to the < S> = 0 phases realised at very early times and again today. The third model, which we call mixing-induced freeze-in, is similar in spirit, but here it is the mixing of dark sector fermions, induced by non-zero < S>, that temporarily boosts the dark matter production rate. For all three scenarios, we carefully dissect the evolution of the dark sector in the early Universe. We compute the DM relic abundance as a function of the model parameters, emphasising the importance of thermal corrections and the proper treatment of phase transitions in the calculation.
Effects of different freezing methods on calcium enriched papaya (Carica papaya L.).
Lovera, Nancy N; Ramallo, Laura; Salvadori, Viviana O
2018-06-01
The effect of calcium impregnation on drip loss, colour, mechanical properties, sensory perception and freezing time on frozen-thawed papaya was studied, evaluating different freezing methods: cryogenic, tunnel and household freezer freezing. Osmotic dehydration as pre-treatment was also evaluated. Freezing in liquid nitrogen was considered an inappropriate method for papaya preservation due to cracking. Calcium impregnation and osmotic dehydration increased tissue firmness and decreased freezing time (freezing time for fresh, calcium impregnated and osmo-dehydrated fruit was 23, 17 and 5 min in a tunnel and 118, 83 and 60 min in a household freezer, respectively). Calcium lactate was the most effective way to protect tissue's firmness before and after a freeze-thaw cycle (maximum stress values approx. 300-400% of the raw tissue for tunnel freezing and 260% for household freezer). Microstructure analysis showed better tissue integrity retention in papaya samples impregnated with calcium lactate than in those with calcium gluconate, after a freezing-thawing cycle, in agreement with the drip loss results. In spite of these results, consumers preferred frozen papaya without pre-treatment or impregnated with calcium gluconate.
A tissue snap-freezing apparatus without sacrificial cryogens
NASA Astrophysics Data System (ADS)
Vanapalli, Srinivas; Jagga, Sahil; Holland, Harry; ter Brake, Marcel
2017-12-01
Molecular technologies in cancer diagnosis require a fresh and frozen tissue, which is obtained by means of snap-freezing. Currently, coolants such as solid carbon dioxide and liquid nitrogen are used to preserve good morphology of the tissue. Using these coolants, snap freezing of tissues for diagnostic and research purposes is often time consuming, laborious, even hazardous and not user friendly. For that reason snap-freezing is not routinely applied at the location of biopsy acquisition. Furthermore, the influence of optimal cooling rate and cold sink temperature on the viability of the cells is not well known. In this paper, a snap-freezing apparatus powered by a small cryocooler is presented that will allow bio-medical research of tissue freezing methods and is safe to use in a hospital. To benchmark this apparatus, cooldown of a standard aluminum cryo-vial in liquid nitrogen is measured and the cooling rate is about -25 K/s between 295 K and 120 K. Sufficient cooling rate is obtained by a forced convective helium gas flow through a gap formed between the cryo-vial and a cold surface and is therefore chosen as the preferred cooling method. A conceptual design of the snap-apparatus with forced flow is discussed in this paper.
Wheeled and standard walkers in Parkinson's disease patients with gait freezing.
Cubo, Esther; Moore, Charity G; Leurgans, Sue; Goetz, Christopher G
2003-10-01
Compare the efficacy of two walking assistance devices (wheeled walker and standard walker) to unassisted walking for patients with PD and gait freezing. Although numerous walking devices are used clinically, their relative effects on freezing and walking speed have never been systematically tested. Nineteen PD patients (14 non-demented) walked under three conditions in randomized order: unassisted walking, standard walker, and wheeled walker. Patients walked up to three times in each condition through a standard course that included rising from a chair, walking through a doorway, straightway walking, pivoting, and return. Total walking time, freezing time and number of freezes were compared for the three conditions using mixed models (walking time) and Friedman's test (freezing). The wheeled walker was further studied by comparing the effect of an attached laser that projected a bar of light on the floor as a visual walking cue. Use of either type of device significantly slowed walking compared to unassisted walking. Neither walker reduced any index of freezing, nor the laser attachment offered any advantage to the wheeled walker. The standard walker increased freezing, and the wheeled walker had no effect on freezing. Among the non-demented subjects (n=14), the same patterns occurred, although the walking speed was less impaired by the wheeled walker than the standard walker in this group. Though walkers may stabilize patients and increase confidence, PD patients walk more slowly when using them, without reducing freezing. Because the wheeled walker was intermediate for walking time and does not aggravate freezing, if walkers are used for these subjects, this type of walker should be favored.
Vutyavanich, Teraporn; Lattiwongsakorn, Worashorn; Piromlertamorn, Waraporn; Samchimchom, Sudarat
2012-01-01
In this study, we compared the effects of repeated freezing/thawing of human sperm by our in-house method of rapid freezing with slow programmable freezing. Sperm samples from 11 normozoospermic subjects were processed through density gradients and divided into three aliquots: non-frozen, rapid freezing and slow programmable freezing. Sperm in the rapid freezing group had better motility and viability than those in the slow freezing group (P<0.01) after the first, second and third cycles of freezing/thawing, but there was no difference in morphology. In the second experiment, rapid freezing was repeated three times in 20 subjects. The samples from each thawing cycle were evaluated for DNA fragmentation using the alkaline comet assay. DNA fragmentation began to increase considerably after the second cycle of freezing/thawing, but to a level that was not clinically important. In the third experiment, rapid freezing was done repeatedly in 10 subjects, until no motile sperm were observed after thawing. The median number of repeated freezing/thawing that yielded no motile sperm was seven (range: 5–8, mean: 6.8). In conclusion, we demonstrated that repeated freezing/thawing of processed semen using our rapid freezing method gave better results than standard slow programmable freezing. This method can help maximize the usage of precious cryopreserved sperm samples in assisted reproduction technology. PMID:23064685
Cold tolerance and freeze-induced glucose accumulation in three terrestrial slugs.
Slotsbo, Stine; Hansen, Lars Monrad; Jordaens, Kurt; Backeljau, Thierry; Malmendal, Anders; Nielsen, Niels Chr; Holmstrup, Martin
2012-04-01
Cold tolerance and metabolic responses to freezing of three slug species common in Scandinavia (Arion ater, Arion rufus and Arion lusitanicus) are reported. Autumn collected slugs were cold acclimated in the laboratory and subjected to freezing conditions simulating likely winter temperatures in their habitat. Slugs spontaneously froze at about -4 °C when cooled under dry conditions, but freezing of body fluids was readily induced at -1 °C when in contact with external ice crystals. All three species survived freezing for 2 days at -1 °C, and some A. rufus and A. lusitanicus also survived freezing at -2 °C. (1)H NMR spectroscopy revealed that freezing of body fluids resulted in accumulation of lactate, succinate and glucose. Accumulation of lactate and succinate indicates that ATP production occurred via fermentative pathways, which is likely a result of oxygen depletion in frozen tissues. Glucose increased from about 6 to 22 μg/mg dry tissue upon freezing in A. rufus, but less so in A. ater and A. lusitanicus. Glucose may thus act as a cryoprotectant in these slugs, although the concentrations are not as high as reported for other freeze tolerant invertebrates. Copyright © 2012 Elsevier Inc. All rights reserved.
Water-cooled probe technique for the study of freeze lining formation
NASA Astrophysics Data System (ADS)
Verscheure, Karel; Campforts, Mieke; Verhaeghe, Frederik; Boydens, Eddy; Blanpain, Bart; Wollants, Patrick; van Camp, Maurits
2006-12-01
Furnace protection by water-cooled freeze linings becomes increasingly important as the metal producing industry attempts to achieve higher process intensities. Systematic investigations of the growth and the resulting microstructure and compositional profile of freeze linings are necessary to understand the behavior of freeze linings, their relation with the industrial process, and their interaction with the wall cooling system. We have developed a technique based on the submergence of a water-cooled probe into a liquid slag bath. Freeze linings of two industrial nonferrous slags have been produced using this technique and their growth, microstructural, and compositional profiles as a function of submergence time were determined. Thermodynamic equilibrium for the investigated slag systems was calculated and compared with the observed microstructures. The freeze linings form in approximately 15 minutes. Close to the water cooling, the freeze linings are predominantly amorphous in structure. With increasing distance from the water cooling, the proportion of crystalline phases increases and bath material is entrapped in the microstructure. Cellular crystals are observed close to the bath. The freeze linings exhibit an approximate homogeneous composition. The results demonstrate that the technique is a successful tool in obtaining information on the growth, microstructure, and composition of freeze linings in industrial water-cooled furnaces.
Emerging freeze-drying process development and scale-up issues.
Patel, Sajal Manubhai; Pikal, Michael J
2011-03-01
Although several guidelines do exist for freeze-drying process development and scale-up, there are still a number of issues that require additional attention. The objective of this review article is to discuss some emerging process development and scale-up issue with emphasis on effect of load condition and freeze-drying in novel container systems such as syringes, Lyoguard trays, ampoules, and 96-well plates. Understanding the heat and mass transfer under different load conditions and for freeze-drying in these novel container systems will help in developing a robust freeze-drying process which is also easier to scale-up. Further research and development needs in these emerging areas have also been addressed. © 2011 American Association of Pharmaceutical Scientists
Detecting depression among adolescents in Santiago, Chile: sex differences.
Araya, Ricardo; Montero-Marin, Jesus; Barroilhet, Sergio; Fritsch, Rosemarie; Gaete, Jorge; Montgomery, Alan
2013-04-23
Depression among adolescents is common but most cases go undetected. Brief questionnaires offer an opportunity to identify probable cases but properly validated cut-off points are often unavailable, especially in non-western countries. Sex differences in the prevalence of depression become marked in adolescence and this needs to be accounted when establishing cut-off points. This study involved adolescents attending secondary state schools in Santiago, Chile. We compared the self-reported Beck Depression Inventory-II with a psychiatric interview to ascertain diagnosis. General psychometric features were estimated before establishing the criterion validity of the BDI-II. The BDI-II showed good psychometric properties with good internal consistency, a clear unidimensional factorial structure, and good capacity to discriminate between cases and non-cases of depression. Optimal cut-off points to establish caseness for depression were much higher for girls than boys. Sex discrepancies were primarily explained by differences in scores among those with depression rather than among those without depression. It is essential to validate scales with the populations intended to be used with. Sex differences are often ignored when applying cut-off points, leading to substantial misclassification. Early detection of depression is essential if we think that early intervention is a clinically important goal.
Visualizing multiattribute Web transactions using a freeze technique
NASA Astrophysics Data System (ADS)
Hao, Ming C.; Cotting, Daniel; Dayal, Umeshwar; Machiraju, Vijay; Garg, Pankaj
2003-05-01
Web transactions are multidimensional and have a number of attributes: client, URL, response times, and numbers of messages. One of the key questions is how to simultaneously lay out in a graph the multiple relationships, such as the relationships between the web client response times and URLs in a web access application. In this paper, we describe a freeze technique to enhance a physics-based visualization system for web transactions. The idea is to freeze one set of objects before laying out the next set of objects during the construction of the graph. As a result, we substantially reduce the force computation time. This technique consists of three steps: automated classification, a freeze operation, and a graph layout. These three steps are iterated until the final graph is generated. This iterated-freeze technique has been prototyped in several e-service applications at Hewlett Packard Laboratories. It has been used to visually analyze large volumes of service and sales transactions at online web sites.
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.
Greco, Kristyn; Mujat, Mircea; Galbally-Kinney, Kristin L; Hammer, Daniel X; Ferguson, R Daniel; Iftimia, Nicusor; Mulhall, Phillip; Sharma, Puneet; Kessler, William J; Pikal, Michael J
2013-06-01
The objective of this study was to assess the feasibility of developing and applying a laboratory tool that can provide three-dimensional product structural information during freeze-drying and which can accurately characterize the collapse temperature (Tc ) of pharmaceutical formulations designed for freeze-drying. A single-vial freeze dryer coupled with optical coherence tomography freeze-drying microscopy (OCT-FDM) was developed to investigate the structure and Tc of formulations in pharmaceutically relevant products containers (i.e., freeze-drying in vials). OCT-FDM was used to measure the Tc and eutectic melt of three formulations in freeze-drying vials. The Tc as measured by OCT-FDM was found to be predictive of freeze-drying with a batch of vials in a conventional laboratory freeze dryer. The freeze-drying cycles developed using OCT-FDM data, as compared with traditional light transmission freeze-drying microscopy (LT-FDM), resulted in a significant reduction in primary drying time, which could result in a substantial reduction of manufacturing costs while maintaining product quality. OCT-FDM provides quantitative data to justify freeze-drying at temperatures higher than the Tc measured by LT-FDM and provides a reliable upper limit to setting a product temperature in primary drying. Copyright © 2013 Wiley Periodicals, Inc.
Freezing of gait in PD: prospective assessment in the DATATOP cohort.
Giladi, N; McDermott, M P; Fahn, S; Przedborski, S; Jankovic, J; Stern, M; Tanner, C
2001-06-26
To study the development of freezing of gait in PD. Freezing of gait is a common, disabling, and poorly understood symptom in PD. The authors analyzed data from 800 patients with early PD from the Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism (DATATOP) clinical trial who were assigned either placebo, deprenyl, tocopherol, or the combination of deprenyl and tocopherol. The primary outcome measure was the time from randomization until the freezing of gait score on the Unified Parkinson's Disease Rating Scale (UPDRS) became positive. Fifty-seven patients (7.1%) had freezing of gait at study entry and 193 (26%) of the remaining patients experienced the symptom by the end of the follow-up period. Those with freezing of gait at baseline had significantly more advanced disease than those without the symptom, as measured by total UPDRS and Hoehn and Yahr stage. High baseline risk factors for developing freezing of gait during the follow-up period were the onset of PD with a gait disorder; higher scores of rigidity, postural instability, bradykinesia and speech; and longer disease duration. In contrast, tremor was strongly associated with a decreased risk for freezing of gait. At the end of follow-up, the signs most strongly associated with the freezing phenomenon were gait, balance, and speech disorders, not rigidity or bradykinesia. Deprenyl treatment was strongly associated with a decreased risk for developing freezing of gait; tocopherol had no effect. Freezing of gait is directly related to duration of PD. Risk factors at onset of disease are the absence of tremor and PD beginning as a gait disorder. The development of freezing of gait in the course of the illness is strongly associated with the development of balance and speech problems, less so with the worsening of bradykinesia, and is not associated with the progression of rigidity. These results support the concept that the freezing phenomenon is distinct from bradykinesia. Deprenyl, in the absence
"On" freezing in Parkinson's disease: resistance to visual cue walking devices.
Kompoliti, K; Goetz, C G; Leurgans, S; Morrissey, M; Siegel, I M
2000-03-01
To measure "on" freezing during unassisted walking (UW) and test if two devices, a modified inverted stick (MIS) and a visual laser beam stick (LBS) improved walking speed and number of "on" freezing episodes in patients with Parkinson's disease (PD). Multiple visual cues can overcome "off' freezing episodes and can be useful in improving gait function in parkinsonian patients. These devices have not been specifically tested in "on" freezing, which is unresponsive to pharmacologic manipulations. Patients with PD, motor fluctuations and freezing while "on," attempted walking on a 60-ft track with each of three walking conditions in a randomized order: UW, MIS, and LBS. Total time to complete a trial, number of freezes, and the ratio of walking time to the number of freezes were compared using Friedman's test. Twenty-eight patients with PD, mean age 67.81 years (standard deviation [SD] 7.54), mean disease duration 13.04 years (SD 7.49), and mean motor Unified Parkinson's Disease Rating Scale score "on" 32.59 (SD 10.93), participated in the study. There was a statistically significant correlation of time needed to complete a trial and number of freezes for all three conditions (Spearman correlations: UW 0.973, LBS 0.0.930, and MIS 0.842). The median number of freezes, median time to walk in each condition, and median walking time per freeze were not significantly different in pairwise comparisons of the three conditions (Friedman's test). Of the 28 subjects, six showed improvement with the MIS and six with the LBS in at least one outcome measure. Assisting devices, specifically based on visual cues, are not consistently beneficial in overcoming "on" freezing in most patients with PD. Because this is an otherwise untreatable clinical problem and because occasional subjects do respond, cautious trials of such devices under the supervision of a health professional should be conducted to identify those patients who might benefit from their long-term use.
Asymmetric pedunculopontine network connectivity in parkinsonian patients with freezing of gait
Fling, Brett W.; Cohen, Rajal G.; Mancini, Martina; Nutt, John G.; Fair, Damian A.
2013-01-01
Freezing of gait is one of the most debilitating symptoms in Parkinson’s disease as it causes falls and reduces mobility and quality of life. The pedunculopontine nucleus is one of the major nuclei of the mesencephalic locomotor region and has neurons related to anticipatory postural adjustments preceding step initiation as well as to the step itself, thus it may be critical for coupling posture and gait to avoid freezing. Because freezing of gait and postural impairments have been related to frontal lesions and frontal dysfunction such as executive function, we hypothesized that freezing is associated with disrupted connectivity between midbrain locomotor regions and medial frontal cortex. We used diffusion tensor imaging to quantify structural connectivity of the pedunculopontine nucleus in patients with Parkinson’s disease with freezing of gait, without freezing, and healthy age-matched controls. We also included behavioural tasks to gauge severity of freezing of gait, quantify gait metrics, and assess executive cognitive functions to determine whether between-group differences in executive dysfunction were related to pedunculopontine nucleus structural network connectivity. Using seed regions from the pedunculopontine nucleus, we were able to delineate white matter connections between the spinal cord, cerebellum, pedunculopontine nucleus, subcortical and frontal/prefrontal cortical regions. The current study is the first to demonstrate differences in structural connectivity of the identified locomotor pathway in patients with freezing of gait. We report reduced connectivity of the pedunculopontine nucleus with the cerebellum, thalamus and multiple regions of the frontal cortex. Moreover, these structural differences were observed solely in the right hemisphere of patients with freezing of gait. Finally, we show that the more left hemisphere-lateralized the pedunculopontine nucleus tract volume, the poorer the performance on cognitive tasks requiring the
Frost heave susceptibility of saturated soil under constant rate of freezing
NASA Astrophysics Data System (ADS)
Ryokai, K.; Iguro, M.; Yoneyama, K.
Introduced are the results of experiments carried out to quantitatively obtain the frost heave pressure and displacement of soil subjected to artificial freezing or freezing around in-ground liquefied natural gas storage tanks. This experiment is conducted to evaluate the frost heave susceptibility of saturated soil under overconsolidation. In other words, this experiment was carried out to obtain the relation of the over-burden pressure and freezing rate to the frost heave ratio by observing the frost heave displacement and freezing time of specimens by freezing the specimens at a constant freezing rate under a constant overburden pressure, while letting water freely flow in and out of the system. Introduced are the procedures for frost heave test required to quantitatively obtain the frost heave displacement and pressure of soil. Furthermore, the relation between the frost heave susceptibility and physical properties of soil obtained by this test is reported.
Hung, Ching-I; Liu, Chia-Yih; Yang, Ching-Hui; Wang, Shuu-Jiun
2016-01-01
No study has compared the associations of headache, anxiety, and depression at baseline with muscle soreness or pain (MS/P) at baseline and at the two-year follow-up point among outpatients with major depressive disorder (MDD). This study aimed to investigate the above issue. This study enrolled 155 outpatients with MDD at baseline, and 131 attended a two-year follow-up appointment. At baseline, migraine was diagnosed based on the International Classification of Headache Disorders, 2(nd) edition. MDD and anxiety disorders were diagnosed using the Structured Clinical Interview for DSM-IV-TR. The visual analog scale was used to evaluate the intensities of headache and MS/P in the neck, shoulder, back, upper limbs, and lower limbs. Depression and anxiety were evaluated using the Hospital Anxiety and Depression Scale. Multiple linear regressions were used to compare the associations of these factors with MS/P. Compared with anxiety disorders, migraine was more strongly associated with MS/P in all areas at baseline and in the upper and lower limbs at follow-up. Headache intensity at baseline was the factor most strongly associated with MS/P in all areas at baseline and follow-up after controlling for depression and anxiety. Headache intensity at baseline predicted MS/P at baseline and follow-up. Migraine and headache intensity are important factors related to MS/P at baseline and follow-up among patients with MDD. Integrating depression and headache treatment might be indicated to improve MS/P.
Freezing of gait in Parkinson's disease: the paradoxical interplay between gait and cognition.
Ricciardi, Lucia; Bloem, Bastiaan R; Snijders, Anke H; Daniele, Antonio; Quaranta, Davide; Bentivoglio, Anna Rita; Fasano, Alfonso
2014-08-01
Freezing of gait is a disabling episodic gait disturbance common in patients with Parkinson's disease. Recent evidences suggest a complex interplay between gait impairment and executive functions. Aim of our study was to evaluate whether specific motor conditions (sitting or walking) influence cognitive performance in patients with or without different types of freezing. Eight healthy controls, eight patients without freezing, nine patients with levodopa-responsive and nine patients with levodopa-resistant freezing received a clinical and neuropsychological assessment during two randomly performed conditions: at rest and during walking. At rest, patients with levodopa-resistant freezing performed worse than patients without freezing on tests of phonological fluency (p = 0.01). No differences among the four groups were detected during walking. When cognitive performances during walking were compared to the performance at rest, there was a significant decline of verbal episodic memory task (Rey Auditory Verbal Learning Test) in patients without freezing and with levodopa-responsive freezing. Interestingly, walking improved performance on the phonological fluency task in patients with levodopa-resistant freezing (p = 0.04). Compared to patients without freezing, patients with levodopa-resistant freezing perform worse when tested while seated in tasks of phonological verbal fluency. Surprisingly, gait was associated with a paradoxical improvement of phonological verbal fluency in the patients with levodopa-resistant freezing whilst walking determined a worsening of episodic memory in the other patient groups. Copyright © 2014 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Ragay-Enot, Monalisa; Lee, Young Hee; Kim, Yong-Gyoo
2017-07-01
A mini multi-fixed-point cell (length 118 mm, diameter 33 mm) containing three materials (In-Zn eutectic (mass fraction 3.8% Zn), Sn and Pb) in a single crucible was designed and fabricated for the easy and economical fixed-point calibration of industrial platinum resistance thermometers (IPRTs) for use in industrial temperature measurements. The melting and freezing behaviors of the metals were investigated and the phase transition temperatures were determined using a commercial dry-block calibrator. Results showed that the melting plateaus are generally easy to realize and are reproducible, flatter and of longer duration. On the other hand, the freezing process is generally difficult, especially for Sn, due to the high supercooling required to initiate freezing. The observed melting temperatures at optimum set conditions were 143.11 °C (In-Zn), 231.70 °C (Sn) and 327.15 °C (Pb) with expanded uncertainties (k = 2) of 0.12 °C, 0.10 °C and 0.13 °C, respectively. This multi-fixed-point cell can be treated as a sole reference temperature-generating system. Based on the results, the realization of melting points of the mini multi-fixed-point cell can be recommended for the direct calibration of IPRTs in industrial applications without the need for a reference thermometer.
Freeze Tape Casting of Functionally Graded Porous Ceramics
NASA Technical Reports Server (NTRS)
Sofie, Stephen W.
2007-01-01
Freeze tape casting is a means of making preforms of ceramic sheets that, upon subsequent completion of fabrication processing, can have anisotropic and/or functionally graded properties that notably include aligned and graded porosity. Freeze tape casting was developed to enable optimization of the microstructures of porous ceramic components for use as solid oxide electrodes in fuel cells: Through alignment and grading of pores, one can tailor surface areas and diffusion channels for flows of gas and liquid species involved in fuel-cell reactions. Freeze tape casting offers similar benefits for fabrication of optimally porous ceramics for use as catalysts, gas sensors, and filters.
Use of freeze-casting in advanced burner reactor fuel design
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lang, A. L.; Yablinsky, C. A.; Allen, T. R.
2012-07-01
This paper will detail the modeling of a fast reactor with fuel pins created using a freeze-casting process. Freeze-casting is a method of creating an inert scaffold within a fuel pin. The scaffold is created using a directional solidification process and results in open porosity for emplacement of fuel, with pores ranging in size from 300 microns to 500 microns in diameter. These pores allow multiple fuel types and enrichments to be loaded into one fuel pin. Also, each pore could be filled with varying amounts of fuel to allow for the specific volume of fission gases created by thatmore » fuel type. Currently fast reactors, including advanced burner reactors (ABR's), are not economically feasible due to the high cost of operating the reactors and of reprocessing the fuel. However, if the fuel could be very precisely placed, such as within a freeze-cast scaffold, this could increase fuel performance and result in a valid design with a much lower cost per megawatt. In addition to competitive costs, freeze-cast fuel would also allow for selective breeding or burning of actinides within specific locations in fast reactors. For example, fast flux peak locations could be utilized on a minute scale to target specific actinides for transmutation. Freeze-cast fuel is extremely flexible and has great potential in a variety of applications. This paper performs initial modeling of freeze-cast fuel, with the generic fast reactor parameters for this model based on EBR-II. The core has an assumed power of 62.5 MWt. The neutronics code used was Monte Carlo N-Particle (MCNP5) transport code. Uniform pore sizes were used in increments of 100 microns. Two different freeze-cast scaffold materials were used: ceramic (MgO-ZrO{sub 2}) and steel (SS316L). Separate models were needed for each material because the freeze-cast ceramic and metal scaffolds have different structural characteristics and overall porosities. Basic criticality results were compiled for the various models
Three keys to the radiation of angiosperms into freezing environments.
Zanne, Amy E; Tank, David C; Cornwell, William K; Eastman, Jonathan M; Smith, Stephen A; FitzJohn, Richard G; McGlinn, Daniel J; O'Meara, Brian C; Moles, Angela T; Reich, Peter B; Royer, Dana L; Soltis, Douglas E; Stevens, Peter F; Westoby, Mark; Wright, Ian J; Aarssen, Lonnie; Bertin, Robert I; Calaminus, Andre; Govaerts, Rafaël; Hemmings, Frank; Leishman, Michelle R; Oleksyn, Jacek; Soltis, Pamela S; Swenson, Nathan G; Warman, Laura; Beaulieu, Jeremy M
2014-02-06
Early flowering plants are thought to have been woody species restricted to warm habitats. This lineage has since radiated into almost every climate, with manifold growth forms. As angiosperms spread and climate changed, they evolved mechanisms to cope with episodic freezing. To explore the evolution of traits underpinning the ability to persist in freezing conditions, we assembled a large species-level database of growth habit (woody or herbaceous; 49,064 species), as well as leaf phenology (evergreen or deciduous), diameter of hydraulic conduits (that is, xylem vessels and tracheids) and climate occupancies (exposure to freezing). To model the evolution of species' traits and climate occupancies, we combined these data with an unparalleled dated molecular phylogeny (32,223 species) for land plants. Here we show that woody clades successfully moved into freezing-prone environments by either possessing transport networks of small safe conduits and/or shutting down hydraulic function by dropping leaves during freezing. Herbaceous species largely avoided freezing periods by senescing cheaply constructed aboveground tissue. Growth habit has long been considered labile, but we find that growth habit was less labile than climate occupancy. Additionally, freezing environments were largely filled by lineages that had already become herbs or, when remaining woody, already had small conduits (that is, the trait evolved before the climate occupancy). By contrast, most deciduous woody lineages had an evolutionary shift to seasonally shedding their leaves only after exposure to freezing (that is, the climate occupancy evolved before the trait). For angiosperms to inhabit novel cold environments they had to gain new structural and functional trait solutions; our results suggest that many of these solutions were probably acquired before their foray into the cold.
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.
Demonstrating Functional Equivalence of Pilot and Production Scale Freeze-Drying of BCG.
Ten Have, R; Reubsaet, K; van Herpen, P; Kersten, G; Amorij, J-P
2016-01-01
Process analytical technology (PAT)-tools were used to monitor freeze-drying of Bacille Calmette-Guérin (BCG) at pilot and production scale. Among the evaluated PAT-tools, there is the novel use of the vacuum valve open/close frequency for determining the endpoint of primary drying at production scale. The duration of primary drying, the BCG survival rate, and the residual moisture content (RMC) were evaluated using two different freeze-drying protocols and were found to be independent of the freeze-dryer scale evidencing functional equivalence. The absence of an effect of the freeze-dryer scale on the process underlines the feasibility of the pilot scale freeze-dryer for further BCG freeze-drying process optimization which may be carried out using a medium without BCG.
Experimental research on durability of recycled aggregate concrete under freeze- thaw cycles
NASA Astrophysics Data System (ADS)
Cheng, Yanqiu; Shang, Xiaoyu; Zhang, Youjia
2017-07-01
The freeze-thaw durability of recycled aggregate concrete has significance for the concrete buildings in the cold region. In this paper, the rapid freezing and thawing cycles experience on recycle aggregate concrete was conducted to study on the effects of recycle aggregate amount, water-binder ratio and fly ash on freeze-thaw durability of recycle aggregate concrete. The results indicates that recycle aggregate amount makes the significant influence on the freeze-thaw durability. With the increase of recycled aggregates amount, the freeze-thaw resistance for recycled aggregate concrete decreases. Recycled aggregate concrete with lower water cement ratio demonstrates better performance of freeze-thaw durability. It is advised that the amount of fly ash is less than 30% for admixture of recycled aggregates in the cold region.
Recent developments in novel freezing and thawing technologies applied to foods.
Wu, Xiao-Fei; Zhang, Min; Adhikari, Benu; Sun, Jincai
2017-11-22
This article reviews the recent developments in novel freezing and thawing technologies applied to foods. These novel technologies improve the quality of frozen and thawed foods and are energy efficient. The novel technologies applied to freezing include pulsed electric field pre-treatment, ultra-low temperature, ultra-rapid freezing, ultra-high pressure and ultrasound. The novel technologies applied to thawing include ultra-high pressure, ultrasound, high voltage electrostatic field (HVEF), and radio frequency. Ultra-low temperature and ultra-rapid freezing promote the formation and uniform distribution of small ice crystals throughout frozen foods. Ultra-high pressure and ultrasound assisted freezing are non-thermal methods and shorten the freezing time and improve product quality. Ultra-high pressure and HVEF thawing generate high heat transfer rates and accelerate the thawing process. Ultrasound and radio frequency thawing can facilitate thawing process by volumetrically generating heat within frozen foods. It is anticipated that these novel technologies will be increasingly used in food industries in the future.
Effect of freezing temperature on the color of frozen salmon.
Ottestad, Silje; Enersen, Grethe; Wold, Jens Petter
2011-09-01
New freezing methods developed with the purpose of improved product quality after thawing can sometimes be difficult to get accepted in the market. The reason for this is the formation of ice crystals that can give the product a temporary color loss and make it less appealing. We have here used microscopy to study ice crystal size as a function of freezing temperature by investigating the voids in the cell tissue left by the ice crystals. We have also investigated how freezing temperature affects the color and the visible absorption spectra of frozen salmon. Freezing temperatures previously determined to be the best for quality after thawing (-40 to -60 °C) were found to cause a substantial loss in perceived color intensity during frozen state. This illustrated the conflict between optimal freezing temperatures with respect to quality after thawing against visual appearance during frozen state. Low freezing temperatures gave many small ice crystals, increased light scattering and an increased absorption level for all wavelengths in the visible region. Increased astaxanthin concentration on the other hand would give higher absorption at 490 nm. The results showed a clear potential of using visible interactance spectroscopy to differentiate between poor product coloration due to lack of pigmentation and temporary color loss due to light scattering by ice crystal. This type of measurements could be a useful tool in the development of new freezing methods and to monitor ice crystal growth during frozen storage. It could also potentially be used by the industry to prove good product quality. In this article we have shown that freezing food products at intermediate to low temperatures (-40 to -80 °C) can result in paler color during frozen state, which could affect consumer acceptance. We have also presented a spectroscopic method that can separate between poor product color and temporary color loss due to freezing. © 2011 Institute of Food Technologists®
Indirect contact freeze water desalination for an ice maker machine - CFD simulation
NASA Astrophysics Data System (ADS)
Jayakody, Harith; Al-Dadah, Raya; Mahmoud, Saad
2017-11-01
To offer for potable water shortages, sea water desalination is a potential solution for the global rising demand for fresh water. The latent heat of fusion is about one-seventh the latent heat of vaporisation, thus indicating the benefit of lower energy consumption for the freeze desalination process. Limited literature is reported on computational fluid dynamics (CFD) on freeze desalination. Therefore, analysing and investigating thermodynamic processes are easily conducted by the powerful tool of CFD. A single unit of ice formation in an ice maker machine was modelled using ANSYS Fluent software three-dimensionally. Energy, species transport and solidification/melting modules were used in building the CFD model. Parametric analysis was conducted using the established CFD model to predict the effects of freezing temperature and the geometry of the ice maker machine; on ice production and the freezing time. Lower freezing temperatures allowed more ice production and faster freezing. Increasing the diameter and the length of the freezing tube enabled more ice to be produced.
ERIC Educational Resources Information Center
Sae, Andy S. W.
1991-01-01
Discusses 27 chemical demonstrations involving inexpensive, readily available materials that illustrate the following concepts: acid/base properties, gas properties, characteristics of carbon dioxide, chemiluminescence, freezing point depression, heat of vaporization; density, polymers, surface tension, polarity/nonpolarity, UV absorption,…
Cavallo, Carola; Cenacchi, Annarita; Facchini, Andrea; Grigolo, Brunella; Kon, Elizaveta; Mariani, Erminia; Pratelli, Loredana; Marcacci, Maurilio
2014-01-01
PRP cryopreservation remains a controversial point. Our purpose was to investigate the effect of freezing/thawing on PRP molecule release, and its effects on the metabolism of chondrocytes and synoviocytes. PRP was prepared from 10 volunteers, and a half volume underwent one freezing/thawing cycle. IL-1β, HGF, PDGF AB/BB, TGF-β1, and VEGF were assayed 1 hour and 7 days after activation. Culture media of chondrocytes and synoviocytes were supplemented with fresh or frozen PRP, and, at 7 days, proliferation, gene expression, and secreted proteins levels were evaluated. Results showed that in the freeze-thawed PRP the immediate and delayed molecule releases were similar or slightly lower than those in fresh PRP. TGF-β1 and PDGF AB/BB concentrations were significantly reduced after freezing both at 1 hour and at 7 days, whereas HGF concentration was significantly lower in frozen PRP at 7 days. In fresh PRP IL-1β and HGF concentrations underwent a significant further increase after 7 days. Similar gene expression was found in chondrocytes cultured with both PRPs, whereas in synoviocytes HGF gene expression was higher in frozen PRP. PRP cryopreservation is a safe procedure, which sufficiently preserves PRP quality and its ability to induce proliferation and the production of ECM components in chondrocytes and synoviocytes. PMID:25136613
Does Anxiety Cause Freezing of Gait in Parkinson's Disease?
Ehgoetz Martens, Kaylena A.; Ellard, Colin G.; Almeida, Quincy J.
2014-01-01
Individuals with Parkinson's disease (PD) commonly experience freezing of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and freezing of gait (Freezers) and 17 PD without freezing of gait (Non-Freezers) were instructed to walk in two virtual environments: (i) across a plank that was located on the ground (LOW), (ii) across a plank above a deep pit (HIGH). Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state). Freezers reported higher levels of anxiety compared to Non-Freezers (p<0.001) and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p<0.001). Freezers experienced significantly more freezing of gait episodes (p = 0.013) and spent a significantly greater percentage of each trial frozen (p = 0.005) when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare freezing of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying freezing of gait and supports the notion that the limbic system may have a profound contribution to freezing in PD. PMID:25250691
Does anxiety cause freezing of gait in Parkinson's disease?
Ehgoetz Martens, Kaylena A; Ellard, Colin G; Almeida, Quincy J
2014-01-01
Individuals with Parkinson's disease (PD) commonly experience freezing of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and freezing of gait (Freezers) and 17 PD without freezing of gait (Non-Freezers) were instructed to walk in two virtual environments: (i) across a plank that was located on the ground (LOW), (ii) across a plank above a deep pit (HIGH). Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state). Freezers reported higher levels of anxiety compared to Non-Freezers (p < 0.001) and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p < 0.001). Freezers experienced significantly more freezing of gait episodes (p = 0.013) and spent a significantly greater percentage of each trial frozen (p = 0.005) when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare freezing of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying freezing of gait and supports the notion that the limbic system may have a profound contribution to freezing in PD.
Intact preservation of environmental samples by freezing under an alternating magnetic field.
Morono, Yuki; Terada, Takeshi; Yamamoto, Yuhji; Xiao, Nan; Hirose, Takehiro; Sugeno, Masaya; Ohwada, Norio; Inagaki, Fumio
2015-04-01
The study of environmental samples requires a preservation system that stabilizes the sample structure, including cells and biomolecules. To address this fundamental issue, we tested the cell alive system (CAS)-freezing technique for subseafloor sediment core samples. In the CAS-freezing technique, an alternating magnetic field is applied during the freezing process to produce vibration of water molecules and achieve a stable, super-cooled liquid phase. Upon further cooling, the temperature decreases further, achieving a uniform freezing of sample with minimal ice crystal formation. In this study, samples were preserved using the CAS and conventional freezing techniques at 4, -20, -80 and -196 (liquid nitrogen) °C. After 6 months of storage, microbial cell counts by conventional freezing significantly decreased (down to 10.7% of initial), whereas that by CAS-freezing resulted in minimal. When Escherichia coli cells were tested under the same freezing conditions and storage for 2.5 months, CAS-frozen E. coli cells showed higher viability than the other conditions. In addition, an alternating magnetic field does not impact on the direction of remanent magnetization in sediment core samples, although slight partial demagnetization in intensity due to freezing was observed. Consequently, our data indicate that the CAS technique is highly useful for the preservation of environmental samples. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.
Heat pump with freeze-up prevention
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.
Heat transfer coefficient of cryotop during freezing.
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).
Julian, Laura J.; Gregorich, Steven E.; Tonner, Chris; Yazdany, Jinoos; Trupin, Laura; Criswell, Lindsey A.; Yelin, ED; Katz, Patricia P.
2013-01-01
Objective Identifying persons with systemic lupus erythematosus (SLE) at risk for depression would facilitate the identification and treatment of an important comorbidity conferring additional risk for poor outcomes. The purpose of this study was to determine the utility of a brief screening measure, the Center for Epidemiologic Studies Depression Scale (CES-D), in detecting mood disorders in persons with SLE. Methods This cross-sectional study examined 150 persons with SLE. Screening cut points were empirically derived using threshold selection methods, and receiver operating characteristic curves were estimated. The empirically derived cut points of the CES-D were used as the screening measures and were compared to other commonly used CES-D cut points in addition to other commonly used methods to screen for depression. Diagnoses of major depressive disorder or other mood disorders were determined using a “gold standard” structured clinical interview. Results Of the 150 persons with SLE, 26% of subjects met criteria for any mood disorder and 17% met criteria for major depressive disorder. Optimal threshold estimations suggested a CES-D cut score of 24 and above, which yielded adequate sensitivity and specificity in detecting major depressive disorder (88% and 93%, respectively) and correctly classified 92% of participants. To detect the presence of any mood disorder, a cut score of 20 and above was suggested, yielding sensitivity and specificity of 87% and correctly classifying 87%. Conclusion These results suggest the CES-D may be a useful screening measure to identify patients at risk for depression. PMID:21312347
'Banking time': egg freezing and the negotiation of future fertility.
Waldby, Catherine
2015-01-01
This paper examines the relatively recent practice of non-medical egg freezing, in which women bank their eggs for later use in conceiving a child. Non-medical egg freezing has only been available for about the last five years, as new vitrification techniques have made the success rates for actual conception more reliable than the earlier method of slow freezing. I draw on interviews with both clinicians and women who have banked their eggs to consider how this novel practice articulates with broader issues about the relationship between sexuality, reproduction and the political economy of household formation. Non-medical egg-freezing provides a technical solution to a number of different problems women face with regard to the elongation of the life course, the extension of education, the cost of household establishment and the iterative nature of relationship formation, thematised by the ubiquity of internet dating among the interviewees. I focus on the ways women used egg freezing to manage and reconcile different forms of time.
Thielen, Marc; Speck, Thomas; Seidel, Robin
2015-01-01
Pomelos (Citrus maxima) are known for their thick peel which—inter alia—serves as energy dissipator when fruits impact on the ground after being shed. It protects the fruit from splitting open and thus enables the contained seeds to stay germinable and to potentially be dispersed by animal vectors. The main part of the peel consists of a parenchymatous tissue that can be interpreted from a materials point of view as open pored foam whose struts are pressurized and filled with liquid. In order to investigate the influence of the water content on the energy dissipation capacity, drop weight tests were conducted with fresh and with freeze-dried peel samples. Based on the coefficient of restitution it was found that freeze-drying markedly reduces the relative energy dissipation capacity of the peel. Measuring the transmitted force during impact furthermore indicated a transition from a uniform collapse of the foam-like tissue to a progressive collapse due to water extraction. Representing the peel by a Maxwell model illustrates that freeze-drying not only drastically reduces the damping function of the dashpots but also stiffens the springs of the model. PMID:26543566
Immunoelectron Microscopy of Cryofixed and Freeze-Substituted Plant Tissues.
Takeuchi, Miyuki; Takabe, Keiji; Mineyuki, Yoshinobu
2016-01-01
Cryofixation and freeze-substitution techniques provide excellent preservation of plant ultrastructure. The advantage of cryofixation is not only in structural preservation, as seen in the smooth plasma membrane, but also in the speed in arresting cell activity. Immunoelectron microscopy reveals the subcellular localization of molecules within cells. Immunolabeling in combination with cryofixation and freeze-substitution techniques provides more detailed information on the immunoelectron-microscopic localization of molecules in the plant cell than can be obtained from chemically fixed tissues. Here, we introduce methods for immunoelectron microscopy of cryofixed and freeze-substituted plant tissues.
Boardman, Leigh; Terblanche, John S; Sinclair, Brent J
2011-08-01
During extracellular freezing, solutes in the haemolymph are concentrated, resulting in osmotic dehydration of the cells, which must be reversed upon thawing. Here, we used freeze tolerant Pyrrharctia isabella (Lepidoptera: Arctiidae) larvae to examine the processes of ion redistribution after thawing. To investigate the effect of the intensity of cold exposure on ion redistribution after thawing, we exposed caterpillars to -14°C, -20°C or -30°C for 35h. To investigate the effect of duration of cold exposure on ion redistribution after thawing, we exposed the caterpillars to -14°C for up to 6 weeks while sampling several time points. The concentrations of Na(+), K(+), Mg(2+) and Ca(2+) were measured after thawing in the haemolymph, fat body, muscle, midgut tissue and hindgut tissue. Being frozen for long durations (>3 weeks) or at low temperatures (-30°C) both result in 100% mortality, although different ions and tissues appear to be affected by each treatment. Both water distribution and ion content changes were detected after thawing, with the largest effects seen in the fat body and midgut tissue. Magnesium homeostasis appears to be vital for post-freeze survival in these larvae. The movement of ions during thawing lagged behind the movement of water, and ion homeostasis was not restored within the same time frame as water homeostasis. Failure to regain ion homeostasis after thawing is therefore implicated in mortality of freeze tolerant insects. Copyright © 2011 Elsevier Ltd. All rights reserved.
Freeze-thaw performance testing of whole concrete railroad ties.
DOT National Transportation Integrated Search
2013-10-01
Freezing and thawing durability tests of prestressed concrete ties are normally performed according to ASTM C666 specifications. Small specimens are cut from the shoulders of concrete ties and tested through 300 cycles of freezing and thawing. Saw-cu...
Disaggregating meteorites by automated freeze thaw
NASA Astrophysics Data System (ADS)
Charles, Christopher R. J.
2011-06-01
An automated freeze-thaw (AFT) instrument for disaggregating meteorites is described. Meteorite samples are immersed in 18.2 MΩ water and hermetically sealed in a clean 30 ml Teflon vial. This vial and its contents are dipped between baths of liquid nitrogen and hot water over a number of cycles by a dual-stepper motor system controlled by LabView. Uniform and periodic intervals of freezing and thawing induce multiple expansions and contractions, such that cracks propagate along natural flaws in the meteorite for a sufficient number of AFT cycles. For the CR2 chondrite NWA801, the boundaries between different phases (i.e., silicates, metal, matrix) became progressively weaker and allowed for an efficient recovery of 500 individual chondrules and chondrule fragments spanning 0.2-4.7 mm diameters after 243 AFT cycles over 103.3 h. Further FT experiments on a basalt analog showed that the time required for freezing and thawing the same number of cycles can be reduced by a factor of ˜4.
Demonstrating Functional Equivalence of Pilot and Production Scale Freeze-Drying of BCG
ten Have, R.; Reubsaet, K.; van Herpen, P.; Kersten, G.; Amorij, J.-P.
2016-01-01
Process analytical technology (PAT)-tools were used to monitor freeze-drying of Bacille Calmette-Guérin (BCG) at pilot and production scale. Among the evaluated PAT-tools, there is the novel use of the vacuum valve open/close frequency for determining the endpoint of primary drying at production scale. The duration of primary drying, the BCG survival rate, and the residual moisture content (RMC) were evaluated using two different freeze-drying protocols and were found to be independent of the freeze-dryer scale evidencing functional equivalence. The absence of an effect of the freeze-dryer scale on the process underlines the feasibility of the pilot scale freeze-dryer for further BCG freeze-drying process optimization which may be carried out using a medium without BCG. PMID:26981867
Freeze shoe sampler for the collection of hyporheic zone sediments and porewater.
Bianchin, M; Smith, L; Beckie, R
2015-01-01
The Starr and Ingleton (1992) drive point piston sampler (DPPS) design was modified by fitting it with a Murphy and Herkelrath (1996) type sample-freezing drive shoe (SFDS), which uses liquid carbon dioxide as a cryogen. Liquid carbon dioxide was used to freeze sediments in the lower 0.1 m of the core and the drive-point piston sealed the core at the top preserving the reductive-oxidation (redox) sensitive sediments from the atmosphere and maintaining natural stratigraphy. The use of nitrogen gas to provide positive pressure on the gas system blocked the ingress of water which froze on contact with the cryogen thus blocking the gas lines with ice. With this adaptation to the gas system cores could be collected at greater depths beneath the static water level. This tool was used to collect intact saturated sediment cores from the hyporheic zone of the tidally influenced Fraser River in Vancouver, British Columbia, Canada where steep geochemical and microbial gradients develop within the interface between discharging anaerobic groundwater and recharging aerobic river water. In total, 25 cores driven through a 1.5 m sampling interval were collected from the river bed with a mean core recovery of 75%. The ability to deploy this method from a fishing vessel makes the tool more cost effective than traditional marine-based drilling operations which often use barges, tug boats, and drilling rigs. © 2014, National Ground Water Association.
Did Water Leave Its Mark on Mars?
ERIC Educational Resources Information Center
Secosky, James J.
1989-01-01
Discusses the missing water on Mars. Describes five experiments simulating conditions on Mars: (1) behavior of dry ice; (2) low-pressure vacuum; (3) freezing point depression; (4) water in hydrated minerals and clay; and (5) properties of carbon dioxide. (YP)
The Structural Properties and Stability of Monoclonal Antibodies at Freezing Conditions
NASA Astrophysics Data System (ADS)
Perevozchikova, Tatiana; Zarraga, Isidro; Scherer, Thomas; Wagner, Norman; Liu, Yun
2013-03-01
Monoclonal Antibodies (MAb) have become a crucial therapeutic agent in a number of anti-cancer treatments. Due to the inherent unstable nature of proteins in an aqueous formulation, a freeze-drying method has been developed to maintain long-term stability of biotherapeutics. The microstructural changes in Mabs during freezing, however, remain not fully described, and it was proposed that the formed morphology of freeze drying samples could affect the final product quality after reconstitution. Furthermore, it is well known that proteins tend to aggregate during the freezing process if a careful processing procedure is not formulated. Small Angle Neutron Scattering (SANS) is a powerful tool to investigate the structural properties and interactions of Mabs during various stages of lyophilization in situ. Here we present the SANS results of freeze-thaw studies on two MAbs at several different freezing temperatures. While the chosen proteins share a significant sequence homology, their freezing properties are found to be strikingly distinctive. We also show the effect of excipients, concentration and quenching speed on the final morphology of the frozen samples. These findings provide critical information for more effective lyophilization schemes for therapeutic proteins, as well as increase our understanding on structural properties of proteins under cryogenic conditions.
Niermann, Hannah C M; Figner, Bernd; Tyborowska, Anna; van Peer, Jacobien M; Cillessen, Antonius H N; Roelofs, Karin
2017-08-01
The Hypothalamic-Pituitary-Adrenal (HPA)-axis plays an important role in the expression of defensive freezing. Adaptive freezing reactivity, characterized by an immediate increase in acute stress and timely termination upon threat offset or need to act, is essential for adequate stress coping. Blunted HPA-axis activity in animals is associated with blunted freezing reactivity and internalizing symptoms. Despite their potential relevance, it remains unknown whether these mechanisms apply to humans and human psychopathology. Using a well-established method combining electrocardiography and posturography, we assessed freezing before, immediately after, and one hour after a stress induction in 92 human adolescents. In line with animal models, human adolescents showed stress-induced freezing, as quantified by relative reductions in heart rate and body sway after, as compared to before, stress. Moreover, relatively lower basal cortisol was associated with reduced stress-induced freezing reactivity (i.e., less immediate freezing and less recovery). Path analyses showed that decreased freezing recovery in individuals with reduced cortisol levels was associated with increased levels of internalizing symptoms. These findings suggest that reduced freezing recovery may be a promising marker for the etiology of internalizing symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.
Cheng, Lina; Sun, Da-Wen; Zhu, Zhiwei; Zhang, Zi
2017-03-04
Freezing plays an important role in food preservation and the emergence of rapid freezing technologies can be highly beneficial to the food industry. This paper reviews some novel food freezing technologies, including high-pressure freezing (HPF), ultrasound-assisted freezing (UAF), electrically disturbed freezing (EF) and magnetically disturbed freezing (MF), microwave-assisted freezing (MWF), and osmo-dehydro-freezing (ODF). HPF and UAF can initiate ice nucleation rapidly, leading to uniform distribution of ice crystals and the control of their size and shape. Specifically, the former is focused on increasing the degree of supercooling, whereas the latter aims to decrease it. Direct current electric freezing (DC-EF) and alternating current electric freezing (AC-EF) exhibit different effects on ice nucleation. DC-EF can promote ice nucleation and AC-EF has the opposite effect. Furthermore, ODF has been successfully used for freezing various vegetables and fruit. MWF cannot control the nucleation temperature, but can decrease supercooling degree, thus decreasing the size of ice crystals. The heat and mass transfer processes during ODF have been investigated experimentally and modeled mathematically. More studies should be carried out to understand the effects of these technologies on food freezing process.
Straller, Georg; Lee, Geoffrey
2017-10-30
Spray-freeze-drying was used to produce shrivelled, partially-collapsed microparticles of pure proteins that may be suitable for use in a ballistic injector. Various modifications of the freeze drying cycle were examined for their effects on collapse of the pure protein microparticles. The use of annealing at a shelf temperature of up to +10°C resulted in no visible particle shrinkage. This was because of the high T g ' of the pure protein. Inclusion of trehalose or sucrose led to particle shrinkage because of the plasticizing effects of the disaccharides on the protein. Only by extending the duration of primary drying from 240 to 2745min at shelf temperatures in the range -12 to -8°C were shrivelled, wrinkled particles of bSA and bCA of reduced porosity obtained. Manipulation of the freeze-drying cycle used for SFD can therefore be used to modify particle morphology and increase particle density. Copyright © 2017 Elsevier B.V. All rights reserved.
Freeze-Thaw Cycles and Soil Biogeochemistry: Implications for Greenhouse Gas emission
NASA Astrophysics Data System (ADS)
Rezanezhad, F.; Milojevic, T.; Oh, D. H.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.
2016-12-01
Freeze-thaw cycles represent a major natural climate forcing acting on soils at middle and high latitudes. Repeated freezing and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical cycling of carbon and nutrients. In this presentation, we focus on how freeze-thaw cycles regulate carbon and nitrogen cycling and how these transformations influence greenhouse gas (GHG) fluxes. We present a novel approach, which combines the acquisition of physical and chemical data in a newly developed experimental soil column system. This system simulates realistic soil temperature profiles during freeze-thaw cycles. A high-resolution, Multi-Fiber Optode (MuFO) microsensor technique was used to detect oxygen (O2) continuously in the column at multiple depths. Surface and subsurface changes to gas and aqueous phase chemistry were measured to delineate the pathways and quantify soil respiration rates during freeze-thaw cycles. The results indicate that the time-dependent release of GHG from the soil surface is influenced by a combination of two key factors. Firstly, fluctuations in temperature and O2 availability affect soil biogeochemical activity and GHG production. Secondly, the recurrent development of a physical ice barrier prevents exchange of gaseous compounds between the soil and atmosphere during freezing conditions; removal of this barrier during thaw conditions increases GHG fluxes. During freezing, O2 levels in the unsaturated zone decreased due to restricted gas exchange with the atmosphere. As the soil thawed, O2 penetrated deeper into the soil enhancing the aerobic mineralization of organic carbon and nitrogen. Additionally, with the onset of thawing a pulse of gas flux occurred, which is attributed to the build-up of respiratory gases in the pore space during freezing. The latter implies enhanced anaerobic respiration as O2 supply ceases when the upper soil layer freezes.
DETAIL OF CONNECTION TO SWITCH POINTS OF TURNOUT 29, LOOKING ...
DETAIL OF CONNECTION TO SWITCH POINTS OF TURNOUT 29, LOOKING EAST. SILVER BOX HOUSES ELECTRICAL CONTACTS FOR POSITION FEEDBACK TO SIGNAL CIRCUITS. SHEET METAL COVERS GAS-FIRED SWITCH HEATER FOR FREEZE PROTECTION IN WINTER. - Baltimore & Ohio Railroad, Z Tower, State Route 46, Keyser, Mineral County, WV
Alcohol Brine Freezing of Japanese Horse Mackerel (Trachurus japonicus) for Raw Consumption
NASA Astrophysics Data System (ADS)
Maeda, Toshimichi; Yuki, Atsuhiko; Sakurai, Hiroshi; Watanabe, Koichiro; Itoh, Nobuo; Inui, Etsuro; Seike, Kazunori; Mizukami, Yoichi; Fukuda, Yutaka; Harada, Kazuki
In order to test the possible application of alcohol brine freezing to Japanese horse mackerel (Trachurus japonicus) for raw consumption, the quality and taste of fish frozen by direct immersion in 60% ethanol brine at -20, -25 and -30°C was compared with those by air freezing and fresh fish without freezing. Cracks were not found during the freezing. Smell of ethanol did not remain. K value, an indicator of freshness, of fish frozen in alcohol brine was less than 8.3%, which was at the same level as those by air freezing and fresh fish. Oxidation of lipid was at the same level as air freezing does, and lower than that of fresh fish. The pH of fish frozen in alcohol brine at -25 and -30°C was 6.5 and 6.6, respectively, which were higher than that by air freezing and that of fresh fish. Fish frozen in alcohol brine was better than that by air and at the same level as fresh fish in total evaluation of sensory tests. These results show that the alcohol brine freezing is superior to air freezing, and fish frozen in alcohol brine can be a material for raw consumption. The methods of thawing in tap water, cold water, refrigerator, and at room temperature were compared. Thawing in tap water is considered to be convenient due to the short thaw time and the quality of thawed fish that was best among the methods.
Effect of moisture content on the invertase activity of freeze-dried S. cerevisiae.
Pitombo, R N; Spring, C; Passos, R F; Tonato, M; Vitolo, M
1994-08-01
The invertase activity of intact Saccharomyces cerevisiae submitted to freezing-thawing was affected by pH, the chemical nature of the buffer, and the freezing cooling rate (CR), leading in some cases to a complete invertase inactivation (acetate buffer, pH 4.0, CR = 0.5 degree C/min). Once established under adequate freezing conditions the invertase activity remained unchanged after freeze-drying. Nevertheless, in some cases the cell-growing capability after freeze-drying diminished around 70%, mainly if the frozen cell suspension was attained through freezing carried out at CR = 0.5 degree C/min. Water sorption isotherms of freeze-dried samples (freeze-dryer Edwards L-4KR; 30 degrees C and 0.1 mB) were determined at 10 and 25 degrees C. The monolayer moisture content (MMC) at each temperature (12.7 and 3.71 for 10 and 25 degrees C, respectively) was calculated from isotherms by applying BET and GAB models. Freeze-dried yeast with water activity (Aw) between 0 and 0.33 (about the MMC value) maintained at 25 degrees C for 235 days and at 89 degrees C for 15 min retained at least 85% of its original invertase activity (IA), whereas samples with Aw > MMC lost at least 60% of its IA. X ray diffraction showed that the freeze-dried cake before and after storage presented an amorphous structure.
Freezing-induced uptake of trehalose into mammalian cells facilitates cryopreservation.
Zhang, Miao; Oldenhof, Harriëtte; Sieme, Harald; Wolkers, Willem F
2016-06-01
The aim of this study was to investigate if membrane-impermeable molecules are taken up by fibroblasts when exposing the cells to membrane phase transitions and/or freezing-induced osmotic forces. The membrane-impermeable fluorescent dye lucifer yellow (LY) was used to visualize and quantify uptake during endocytosis, and after freezing-thawing. In addition, trehalose uptake after freezing and thawing was studied. Fourier transform infrared spectroscopic studies showed that fibroblasts display a minor non-cooperative phase transition during cooling at suprazero temperatures, whereas cells display strong highly cooperative fluid-to-gel membrane phase transitions during freezing, both in the absence and presence of protectants. Cells do not show uptake of LY upon passing the suprazero membrane phase transition at 30-10°C, whereas after freezing and thawing cells show intracellular LY equally distributed within the cell. Both, LY and trehalose are taken up by fibroblasts after freezing and thawing with loading efficiencies approaching 50%. When using 250 mM extracellular trehalose during cryopreservation, intracellular concentrations greater than 100 mM were determined after thawing. A plot of cryosurvival versus the cooling rate showed a narrow inverted-'U'-shaped curve with an optimal cooling rate of 40°C min(-1). Diluting cells cryopreserved with trehalose in isotonic cell culture medium resulted in a loss of cell viability, which was attributed to intracellular trehalose causing an osmotic imbalance. Taken together, mammalian cells can be loaded with membrane-impermeable compounds, including the protective agent trehalose, by subjecting the cells to freezing-induced osmotic stress. Copyright © 2016 Elsevier B.V. All rights reserved.
Freeze-drying of silica nanoparticles: redispersibility toward nanomedicine applications.
Picco, Agustin S; Ferreira, Larissa F; Liberato, Michelle S; Mondo, Gabriela B; Cardoso, Mateus B
2018-01-01
To study freeze-drying of silica nanoparticles (SiO 2 NPs) in order to find suitable conditions to produce lyophilized powders with no aggregation after resuspension and storage. SiO 2 NPs were synthesized using a Stöber-based procedure, and characterized by scanning electron microscopy, dynamic light scattering and nitrogen adsorption/desorption isotherms. SiO 2 NPs hydrodynamic diameters were compared prior and after freeze-drying in the presence/absence of carbohydrate protectants. Glucose was found to be the most suitable protectant against the detrimental effects of lyophilization. The minimum concentration of carbohydrate required to effectively protect SiO 2 NPs from aggregation during freeze-drying is influenced by the nanoparticle's size and texture. Negligible aggregation was observed during storage. Carbohydrates can be used during SiO 2 NPs freeze-drying process to obtain redispersable solids that maintain original sizes without residual aggregation.
Investigation of TiC C Eutectic and WC C Peritectic High-Temperature Fixed Points
NASA Astrophysics Data System (ADS)
Sasajima, Naohiko; Yamada, Yoshiro
2008-06-01
TiC C eutectic (2,761°C) and WC C peritectic (2,749°C) fixed points were investigated to compare their potential as high-temperature thermometric reference points. Two TiC C and three WC C fixed-point cells were constructed, and the melting and freezing plateaux were evaluated by means of radiation thermometry. The repeatability of the TiC C eutectic within a day was 60 mK with a melting range roughly 200 mK. The repeatability of the melting temperature of the WC C peritectic within 1 day was 17 mK with a melting range of ˜70 mK. The repeatability of the freezing temperature of the WC C peritectic was 21 mK with a freezing range less than 20 mK. One of the TiC C cells was constructed from a TiC and graphite powder mixture. The filling showed the reaction with the graphite crucible was suppressed and the ingot contained less voids, although the lack of high-purity TiC powder poses a problem. The WC C cells were easily constructed, like metal carbon eutectic cells, without any evident reaction with the crucible. From these results, it is concluded that the WC C peritectic has more potential than the TiC C eutectic as a high-temperature reference point. The investigation of the purification of the TiC C cell during filling and the plateau observation are also reported.
The origins and evolution of freeze-etch electron microscopy
Heuser, John E.
2011-01-01
The introduction of the Balzers freeze-fracture machine by Moor in 1961 had a much greater impact on the advancement of electron microscopy than he could have imagined. Devised originally to circumvent the dangers of classical thin-section techniques, as well as to provide unique en face views of cell membranes, freeze-fracturing proved to be crucial for developing modern concepts of how biological membranes are organized and proved that membranes are bilayers of lipids within which proteins float and self-assemble. Later, when freeze-fracturing was combined with methods for freezing cells that avoided the fixation and cryoprotection steps that Moor still had to use to prepare the samples for his original invention, it became a means for capturing membrane dynamics on the millisecond time-scale, thus allowing a deeper understanding of the functions of biological membranes in living cells as well as their static ultrastructure. Finally, the realization that unfixed, non-cryoprotected samples could be deeply vacuum-etched or even freeze-dried after freeze-fracturing opened up a whole new way to image all the other molecular components of cells besides their membranes and also provided a powerful means to image the interactions of all the cytoplasmic components with the various membranes of the cell. The purpose of this review is to outline the history of these technical developments, to describe how they are being used in electron microscopy today and to suggest how they can be improved in order to further their utility for biological electron microscopy in the future. PMID:21844598
Method of freezing living cells and tissues with improved subsequent survival
Senkan, Selim M.; Hirsch, Gerald P.
1980-01-01
This invention relates to an improved method for freezing red blood cells, ther living cells, or tissues with improved subsequent survival, wherein constant-volume freezing is utilized that results in significantly improved survival compared with constant-pressure freezing; optimization is attainable through the use of different vessel geometries, cooling baths and warming baths, and sample concentrations.
Model for heat and mass transfer in freeze-drying of pellets.
Trelea, Ioan Cristian; Passot, Stéphanie; Marin, Michèle; Fonseca, Fernanda
2009-07-01
Lyophilizing frozen pellets, and especially spray freeze-drying, have been receiving growing interest. To design efficient and safe freeze-drying cycles, local temperature and moisture content in the product bed have to be known, but both are difficult to measure in the industry. Mathematical modeling of heat and mass transfer helps to determine local freeze-drying conditions and predict effects of operation policy, and equipment and recipe changes on drying time and product quality. Representative pellets situated at different positions in the product slab were considered. One-dimensional transfer in the slab and radial transfer in the pellets were assumed. Coupled heat and vapor transfer equations between the temperature-controlled shelf, the product bulk, the sublimation front inside the pellets, and the chamber were established and solved numerically. The model was validated based on bulk temperature measurement performed at two different locations in the product slab and on partial vapor pressure measurement in the freeze-drying chamber. Fair agreement between measured and calculated values was found. In contrast, a previously developed model for compact product layer was found inadequate in describing freeze-drying of pellets. The developed model represents a good starting basis for studying freeze-drying of pellets. It has to be further improved and validated for a variety of product types and freeze-drying conditions (shelf temperature, total chamber pressure, pellet size, slab thickness, etc.). It could be used to develop freeze-drying cycles based on product quality criteria such as local moisture content and glass transition temperature.
NASA Astrophysics Data System (ADS)
Cai, Haibing; Xu, Liuxun; Yang, Yugui; Li, Longqi
2018-05-01
Artificial liquid nitrogen freezing technology is widely used in urban underground engineering due to its technical advantages, such as simple freezing system, high freezing speed, low freezing temperature, high strength of frozen soil, and absence of pollution. However, technical difficulties such as undefined range of liquid nitrogen freezing and thickness of frozen wall gradually emerge during the application process. Thus, the analytical solution of the freezing-temperature field of a single pipe is established considering the freezing temperature of soil and the constant temperature of freezing pipe wall. This solution is then applied in a liquid nitrogen freezing project. Calculation results show that the radius of freezing front of liquid nitrogen is proportional to the square root of freezing time. The radius of the freezing front also decreases with decreased the freezing temperature, and the temperature gradient of soil decreases with increased distance from the freezing pipe. The radius of cooling zone in the unfrozen area is approximately four times the radius of the freezing front. Meanwhile, the numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe is conducted using the Abaqus finite-element program. Results show that the numerical simulation of soil temperature distribution law well agrees with the analytical solution, further verifies the reliability of the established analytical solution of the liquid nitrogen freezing-temperature field of a single pipe.
Kuu, Wei Y; Nail, Steven L; Sacha, Gregory
2009-03-01
The purpose of this study was to perform a rapid determination of vial heat transfer parameters, that is, the contact parameter K(cs) and the separation distance l(v), using the sublimation rate profiles measured by tunable diode laser absorption spectroscopy (TDLAS). In this study, each size of vial was filled with pure water followed by a freeze-drying cycle using a LyoStar II dryer (FTS Systems) with step-changes of the chamber pressure set-point at to 25, 50, 100, 200, 300, and 400 mTorr. K(cs) was independently determined by nonlinear parameter estimation using the sublimation rates measured at the pressure set-point of 25 mTorr. After obtaining K(cs), the l(v) value for each vial size was determined by nonlinear parameter estimation using the pooled sublimation rate profiles obtained at 25 to 400 mTorr. The vial heat transfer coefficient K(v), as a function of the chamber pressure, was readily calculated, using the obtained K(cs) and l(v) values. It is interesting to note the significant difference in K(v) of two similar types of 10 mL Schott tubing vials, primary due to the geometry of the vial-bottom, as demonstrated by the images of the contact areas of the vial-bottom. (c) 2008 Wiley-Liss, Inc. and the American Pharmacists Association
Thermodynamical effects accompanied freezing of two water layers separated by sea ice sheet
NASA Astrophysics Data System (ADS)
Bogorodsky, Petr; Marchenko, Aleksey
2014-05-01
The process of melt pond freezing is very important for generation of sea ice cover thermodynamic and mass balance during winterperiod. However, due to significant difficulties of field measurements the available data of model estimations still have no instrumental confirmation. In May 2009 the authors carried out laboratory experiment on freezing of limited water volume in the University Centre in Svalbard ice tank. In the course of experiment fresh water layer of 27.5 cm thickness at freezing point poured on the 24 cm sea ice layer was cooled during 50 hours at the temperature -10º C and then once again during 60 hours at -20º C. For revealing process typical characteristics the data of continuous measurements of temperature and salinity in different phases were compared with data of numerical computations obtained with thermodynamic model which was formulated in the frames of 1-D equation system (infinite extension of water freezing layer) and adapted to laboratory conditions. The known surprise of the experiment became proximity of calculated and measured estimates of process dynamics that confirmed the adequacy of the problem mathematical statement (excluding probably process finale stage). This effect can be explained by formation of cracks on the upper layer of ice at sharp decreases of air temperature, which temporary compensated hydrostatic pressure growth during freezing of closed water volume. Another compensated mechanism can be migration of brine through the lower layer of ice under influence of vertical pressure gradient and also rejection of gas dissolved in water which increased its compressibility. During 110 hours cooling thickness of water layer between ice layers reduced approximately to 2 cm. According to computations this layer is not chilled completely but keeps as thin brine interlayer within ice body whose thickness (about units of mm) is determined by temperature fluctuations of cooled surface. Nevertheless, despite good coincidence of
King, Laurie A.; Cohen, Rajal G.; Horak, Fay B.
2016-01-01
People with Parkinson disease (PD) who show freezing of gait also have dysfunction in cognitive domains that interact with mobility. Specifically, freezing of gait is associated with executive dysfunction involving response inhibition, divided attention or switching attention, and visuospatial function. The neural control impairments leading to freezing of gait have recently been attributed to higher-level, executive and attentional cortical processes involved in coordinating posture and gait rather than to lower-level, sensorimotor impairments. To date, rehabilitation for freezing of gait primarily has focused on compensatory mobility training to overcome freezing events, such as sensory cueing and voluntary step planning. Recently, a few interventions have focused on restitutive, rather than compensatory, therapy. Given the documented impairments in executive function specific to patients with PD who freeze and increasing evidence of overlap between cognitive and motor function, incorporating cognitive challenges with mobility training may have important benefits for patients with freezing of gait. Thus, a novel theoretical framework is proposed for exercise interventions that jointly address both the specific cognitive and mobility challenges of people with PD who freeze. PMID:26381808
Folic acid content in thermostabilized and freeze-dried space shuttle foods
NASA Technical Reports Server (NTRS)
Lane, H. W.; Nillen, J. L.; Kloeris, V. L.
1995-01-01
This study was designed to determine whether freeze-dried and thermostabilized foods on a space shuttle contain adequate folate and to investigate any effects of freeze-drying on folacin. Frozen vegetables were analyzed after three states of processing: thawed; cooked; and rehydrated. Thermostabilized items were analyzed as supplied with no further processing. Measurable folate decreased in some freeze-dried vegetables and increased in others. Folacin content of thermostabilized food items was comparable with published values. We concluded that although the folacin content of some freeze-dried foods was low, adequate folate is available from the shuttle menu to meet RDA guidelines.
Moore, Jayma A; Payne, Scott A
2012-01-01
Fungi often are found within plant tissues where they cannot be visualized with the scanning electron microscope (SEM). We present a simple way to reveal cell interiors while avoiding many common causes of artifact. Freeze-fracture of leaf tissue using liquid nitrogen during the 100% ethanol step of the dehydration process just before critical point drying is useful in exposing intracellular fungi to the SEM.
Mayr, Stefan; Gruber, Andreas; Bauer, Helmut
2003-07-01
Freezing and thawing lead to xylem embolism when gas bubbles caused by ice formation expand during the thaw process. However, previous experimental studies indicated that conifers are resistant to freezing-induced embolism, unless xylem pressure becomes very negative during the freezing. In this study, we show that conifers experienced freezing-induced embolism when exposed to repeated freeze-thaw cycles and simultaneously to drought. Simulating conditions at the alpine timberline (128 days with freeze-thaw events and thawing rates of up to 9.5 K h(-1) in the xylem of exposed twigs during winter), young trees of Norway spruce [Picea abies (L.) Karst.] and stone pine (Pinus cembra L.) were exposed to 50 and 100 freeze-thaw cycles. This treatment caused a significant increase in embolism rates in drought-stressed samples. Upon 100 freeze-thaw cycles, vulnerability thresholds (50% loss of conductivity) were shifted 1.8 MPa (Norway spruce) and 0.8 MPa (stone pine) towards less negative water potentials. The results demonstrate that freeze-thaw cycles are a possible reason for winter-embolism in conifers observed in several field studies. Freezing-induced embolism may contribute to the altitudinal limits of conifers.
Depression, diet and exercise.
Jacka, Felice N; Berk, Michael
2013-09-16
Unhealthy lifestyle behaviour is driving an increase in the burden of chronic non-communicable diseases worldwide. Recent evidence suggests that poor diet and a lack of exercise contribute to the genesis and course of depression. While studies examining dietary improvement as a treatment strategy in depression are lacking, epidemiological evidence clearly points to diet quality being of importance to the risk of depression. Exercise has been shown to be an effective treatment strategy for depression, but this is not reflected in treatment guidelines, and increased physical activity is not routinely encouraged when managing depression in clinical practice. Recommendations regarding dietary improvement, increases in physical activity and smoking cessation should be routinely given to patients with depression. Specialised and detailed advice may not be necessary. Recommendations should focus on following national guidelines for healthy eating and physical activity.
Rubber closures for freeze-dried products.
Hopkins, G H
1976-10-01
Once a biological product has been developed to perform its required medical or pharmaceutical function, it is essential that a container-closure system by chosen which will preserve the efficacy of the product up to the point of administration. The general requirements applicable to proper closure function will be reviewed and the suitability of natural and synthetic elastomers to perform these functions will be discussed. The specialized application of elastomeric materials as closures for freeze-dried products presents additional requirements which are superimposed upon those previously discussed. The first of these unique considerations relates to the proper physical design which will permit the outgassing of water vapor during the sublimation step in the lyophilizing chamber. During this outgassing the design must also permit the closure to remain affixed in the neck while only partially inserted. Since these preparations are lyophilized because they are unstable in aqueous solutions, the elastomer used must constitute an effective barrier to the transmission of moisture vapor through the closure. The MVT and gas transmission properties of elastomers will be discussed. Special consideration will be given to the extremely low temperatures used in the sublimation, stoppering, and storage before use of lyophilized products. The phenomenon of glass transition points with different elastomers will be explained as its relation to satisfactory performance of the closure function at low temperatures.
Effect of freeze/thaw cycles on several biomarkers in urine from patients with kidney disease.
Zhang, Yinan; Luo, Yi; Lu, Huijuan; Wang, Niansong; Shen, Yixie; Chen, Ruihua; Fang, Pingyan; Yu, Hong; Wang, Congrong; Jia, Weiping
2015-04-01
Urine samples were collected from eleven randomly selected patients with kidney disease, including diabetic nephropathy, chronic nephritis, and nephritic syndrome. Urine samples were treated with one of four protocols for freezing and thawing: freeze directly and thaw directly; freeze directly and thaw by temperature gradient; freeze by temperature gradient and thaw directly; and freeze by temperature gradient and thaw by temperature gradient. After one to six freeze/thaw cycles at -20°C or -80°C, different biomarkers showed differential stabilities. The concentrations of total protein, calcium, and potassium did not change significantly after five freeze/thaw cycles at either -20°C or -80°C. Albumin could only sustain three freeze/thaw cycles at -20°C before it started to degrade. We recommend that urine be stored at -80°C as albumin and the organic ions could sustain five and six freeze/thaw cycles, respectively, using the simple "direct freeze and direct thaw" protocol. Furthermore, in most cases, gradient freeze/thaw cycles are not necessary for urine sample storage.
Dynamic Melting of Freezing Droplets on Ultraslippery Superhydrophobic Surfaces.
Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli
2017-03-08
Condensed droplet freezing and freezing droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the freezing delay performance of the surface is common, the melting of the freezing droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.
Transcriptome Analysis of Spartina pectinata in Response to Freezing Stress
Nah, Gyoungju; Lee, Moonsub; Kim, Do-Soon; Rayburn, A. Lane; Voigt, Thomas; Lee, D. K.
2016-01-01
Prairie cordgrass (Spartina pectinata), a perennial C4 grass native to the North American prairie, has several distinctive characteristics that potentially make it a model crop for production in stressful environments. However, little is known about the transcriptome dynamics of prairie cordgrass despite its unique freezing stress tolerance. Therefore, the purpose of this work was to explore the transcriptome dynamics of prairie cordgrass in response to freezing stress at -5°C for 5 min and 30 min. We used a RNA-sequencing method to assemble the S. pectinata leaf transcriptome and performed gene-expression profiling of the transcripts under freezing treatment. Six differentially expressed gene (DEG) groups were categorized from the profiling. In addition, two major consecutive orders of gene expression were observed in response to freezing; the first being the acute up-regulation of genes involved in plasma membrane modification, calcium-mediated signaling, proteasome-related proteins, and transcription regulators (e.g., MYB and WRKY). The follow-up and second response was of genes involved in encoding the putative anti-freezing protein and the previously known DNA and cell-damage-repair proteins. Moreover, we identified the genes involved in epigenetic regulation and circadian-clock expression. Our results indicate that freezing response in S. pectinata reflects dynamic changes in rapid-time duration, as well as in metabolic, transcriptional, post-translational, and epigenetic regulation. PMID:27032112
Quality Evaluation of Pork with Various Freezing and Thawing Methods
2014-01-01
In this study, the physicochemical and sensory quality characteristics due to the influence of various thawing methods on electro-magnetic and air blast frozen pork were examined. The packaged pork samples, which were frozen by air blast freezing at −45℃ or electro-magnetic freezing at −55℃, were thawed using 4 different methods: refrigeration (4±1℃), room temperature (RT, 25℃), cold water (15℃), and microwave (2450 MHz). Analyses were carried out to determine the drip and cooking loss, water holding capacity (WHC), moisture content and sensory evaluation. Frozen pork thawed in a microwave indicated relatively less thawing loss (0.63-1.24%) than the other thawing methods (0.68-1.38%). The cooking loss after electro-magnetic freezing indicated 37.4% by microwave thawing, compared with 32.9% by refrigeration, 36.5% by RT, and 37.2% by cold water in ham. The thawing of samples frozen by electro-magnetic freezing showed no significant differences between the methods used, while the moisture content was higher in belly thawed by microwave (62.0%) after electro-magnetic freezing than refrigeration (54.8%), RT (61.3%), and cold water (61.1%). The highest overall acceptability was shown for microwave thawing after electro-magnetic freezing but there were no significant differences compared to that of the other samples. PMID:26761493
Effects of freezing on the bactericidal activity of human milk.
Takci, Sahin; Gulmez, Dolunay; Yigit, Sule; Dogan, Ozlem; Dik, Kezban; Hascelik, Gulsen
2012-08-01
Storage of human milk by freezing has been recommended for long-term storage. The present study analyzed the bactericidal activity of human milk on Escherichia coli and Pseudomonas aeruginosa and determined the changes in bactericidal activity following freezing at -20°C and -80°C for 1 month and 3 months. Forty-eight milk samples were collected from 48 lactating mothers. Each sample was divided into 10 aliquots. Two of the samples were processed immediately and the others were stored at both -20°C and -80°C until analysis after 1 month and 3 months of freezing. All of the fresh milk samples showed bactericidal activity against E coli and P aeruginosa. Freezing at -20°C for 1 month did not cause statistically significant alteration in bactericidal activity (P > 0.017), whereas storage for 3 months lowered the degree of bactericidal activity significantly (P < 0.017) against E coli. Bactericidal activity was protected when the samples were stored at -80°C. There was no statistically significant difference in the bactericidal activity of human milk against E coli between freezing at -20°C and -80°C for 1 month (P > 0.017); however, when milk was stored for 3 months, -80°C was significantly more protective (P < 0.017). Freezing at -20°C and -80°C for 1 month and 3 months did not cause any significant change in bactericidal activity against P aeruginosa (P > 0.05). Storage by freezing at -80°C is more appropriate to keep bactericidal capacity of stored human milk >1 month if affordable and available, especially in intensive care settings.
Ali, Farman; Wharton, David A.
2014-01-01
Taking advantage of their optical transparency, we clearly observed the third stage infective juveniles (IJs) of Steinernema feltiae freezing under a cryo-stage microscope. The IJs froze when the water surrounding them froze at −2°C and below. However, they avoid inoculative freezing at −1°C, suggesting cryoprotective dehydration. Freezing was evident as a sudden darkening and cessation of IJs' movement. Freeze substitution and transmission electron microscopy confirmed that the IJs of S. feltiae freeze intracellularly. Ice crystals were found in every compartment of the body. IJs frozen at high sub-zero temperatures (−1 and −3°C) survived and had small ice crystals. Those frozen at −10°C had large ice crystals and did not survive. However, the pattern of ice formation was not well-controlled and individual nematodes frozen at −3°C had both small and large ice crystals. IJs frozen by plunging directly into liquid nitrogen had small ice crystals, but did not survive. This study thus presents the evidence that S. feltiae is only the second freeze tolerant animal, after the Antarctic nematode Panagrolaimus davidi, shown to withstand extensive intracellular freezing. PMID:24769523
Does freeze-all policy affect IVF outcomes in poor responders?
Roque, Matheus; Valle, Marcello; Sampaio, Marcos; Geber, Selmo
2017-12-27
To evaluate whether the freeze-all strategy affects in vitro fertilization (IVF) outcomes in poor ovarian responders following the Bologna criteria. We performed a retrospective cohort study conducted between January 2012 and December 2016. A total of 433 poor responders (per the Bologna criteria) fulfilled the inclusion/exclusion criteria and were included in the study, with 277 patients included in the fresh group and 156 in the freeze-all group. All patients were submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone antagonist protocol and cleavage-stage embryo transfer (ET). The main outcome measure was ongoing pregnancy rate. Secondary outcomes included implantation and clinical pregnancy rates. The freeze-all strategy was implemented when the progesterone serum level was >1.5 ng/mL on the trigger day, when the endometrium was <7 mm on the trigger day, or as a patient preference. Patients with previous failed fresh embryo transfer were also submitted to fresh or freeze-all strategy considering the indications mentioned above. The patients' mean age in the freeze-all group was 39.5±3.6 years, while that of patients in the fresh group was 39.7±3.8 years (P=0.54). The mean number of embryos transferred (nET) was 1.53±0.6 and 1.60±0.6 (P=0.12) in the freeze-all and fresh groups, respectively. Ongoing pregnancy rates did not significantly differ between the freeze-all and fresh groups (9.6% versus 10.1%, respectively; Relative Risk [RR]: 0.95; 95% CI: 0.52-1.73), nor did the clinical pregnancy rates (14.1% versus 13.7%, respectively; RR: 1.03; 95% CI: 0.63-1.76). Implantation rates were 9.6% and 9.8% (P=0.82) in the freeze-all and fresh groups, respectively. The logistic regression analysis (including age, antral follicle count [AFC], the number of retrieved oocytes, the number of mature oocytes, nET, and fresh versus freeze-all strategy) indicated that age (P<0.001) and the nET (P=0.039) were the only independent variables
Breeding of Freeze-tolerant Yeast and the Mechanisms of Stress-tolerance
NASA Astrophysics Data System (ADS)
Hino, Akihiro
Frozen dough method have been adopted in the baking industry to reduce labor and to produce fresh breads in stores. New freeze-tolerant yeasts for frozen dough preparations were isolated from banana peel and identified. To obtain strains that have fermentative ability even after several months of frozen storage in fermented dough, we attempted to breed new freeze-tolerantstrain. The hybrid between S.cerevisiae, which is a isolated freeze-tolerant strain, and a strain isolated from bakers' yeast with sexual conjugation gave a good quality bread made from frozen dough method. Freeze-tolerant strains showed higher surviving and trehalose accumulating abilities than freeze-sensitive strains. The freeze tolerance of the yeasts was associated with the basal amount of intracellular trehalose after rapid degradation at the onset of the prefermentation period. The complicated metabolic pathway and the regulation system of trehalose in yeast cells are introduced. The trehalose synthesis may act as a metabolic buffer system which contribute to maintain the intracellular inorganic phosphate and as a feedback regulation system in the glycolysis. However, it is not known enough how the trehalose protects yeast cells from stress.
Visual Indicators on Vaccine Boxes as Early Warning Tools to Identify Potential Freeze Damage.
Angoff, Ronald; Wood, Jillian; Chernock, Maria C; Tipping, Diane
2015-07-01
The aim of this study was to determine whether the use of visual freeze indicators on vaccines would assist health care providers in identifying vaccines that may have been exposed to potentially damaging temperatures. Twenty-seven sites in Connecticut involved in the Vaccine for Children Program participated. In addition to standard procedures, visual freeze indicators (FREEZEmarker ® L; Temptime Corporation, Morris Plains, NJ) were affixed to each box of vaccine that required refrigeration but must not be frozen. Temperatures were monitored twice daily. During the 24 weeks, all 27 sites experienced triggered visual freeze indicator events in 40 of the 45 refrigerators. A total of 66 triggered freeze indicator events occurred in all 4 types of refrigerators used. Only 1 of the freeze events was identified by a temperature-monitoring device. Temperatures recorded on vaccine data logs before freeze indicator events were within the 35°F to 46°F (2°C to 8°C) range in all but 1 instance. A total of 46,954 doses of freeze-sensitive vaccine were stored at the time of a visual freeze indicator event. Triggered visual freeze indicators were found on boxes containing 6566 doses (14.0% of total doses). Of all doses stored, 14,323 doses (30.5%) were of highly freeze-sensitive vaccine; 1789 of these doses (12.5%) had triggered indicators on the boxes. Visual freeze indicators are useful in the early identification of freeze events involving vaccines. Consideration should be given to including these devices as a component of the temperature-monitoring system for vaccines.
van Emmerik, Arnold A P; Hamaker, Ellen L
2017-09-04
This study investigated whether Vincent van Gogh became increasingly self-focused-and thus vulnerable to depression-towards the end of his life, through a quantitative analysis of his written pronoun use over time. A change-point analysis was conducted on the time series formed by the pronoun use in Van Gogh's letters. We used time as a predictor to see whether there was evidence for increased self-focus towards the end of Van Gogh's life, and we compared this to the pattern in the letters written before his move to Arles. Specifically, we examined Van Gogh's use of first person singular pronouns (FPSP) and first person plural pronouns (FPPP) in the 415 letters he wrote while working as an artist before his move to Arles, and in the next 248 letters he wrote after his move to Arles until his death in Auvers-sur-Oise. During the latter period, Van Gogh's use of FPSP showed an annual increase of 0.68% ( SE = 0.15, p < 0.001) and his use of FPPP showed an annual decrease of 0.23% ( SE = 0.04, p < 0.001), indicating increasing self-focus and vulnerability to depression. This trend differed from Van Gogh's pronoun use in the former period (which showed no significant trend in FPSP, and an annual increase of FPPP of 0.03%, SE = 0.02, p = 0.04). This study suggests that Van Gogh's death was preceded by a gradually increasing self-focus and vulnerability to depression. It also illustrates how existing methods (i.e., quantitative linguistic analysis and change-point analysis) can be combined to study specific research questions in innovative ways.
An Investigation of the Cryogenic Freezing of Water in Non-Metallic Pipelines
NASA Astrophysics Data System (ADS)
Martin, C. I.; Richardson, R. N.; Bowen, R. J.
2004-06-01
Pipe freezing is increasingly used in a range of industries to solve otherwise intractable pipe line maintenance and servicing problems. This paper presents the interim results from an experimental study on deliberate freezing of polymeric pipelines. Previous and contemporary works are reviewed. The object of the current research is to confirm the feasibility of ice plug formation within a polymeric pipe as a method of isolation. Tests have been conducted on a range of polymeric pipes of various sizes. The results reported here all relate to freezing of horizontal pipelines. In each case the process of plug formation was photographed, the frozen plug pressure tested and the pipe inspected for signs of damage resulting from the freeze procedure. The time to freeze was recorded and various temperatures logged. These tests have demonstrated that despite the poor thermal and mechanical properties of the polymers, freezing offers a viable alternative method of isolation in polymeric pipelines.
Ultrasound assisted immersion freezing of broccoli (Brassica oleracea L. var. botrytis L.).
Xin, Ying; Zhang, Min; Adhikari, Benu
2014-09-01
The aim of this study was to research the ultrasound-assisted freezing (UAF) of broccoli. CaCl2 solution was used as freezing medium. The comparative advantage of using UAF over normal freezing on the freezing time, cell-wall bound calcium to total calcium ratio, textural properties, color, drip loss and L-ascorbic acid contents was evaluated. The application of UAF at selected acoustic intensity with a range of 0.250-0.412 W/cm(2) decreased the freezing time and the loss of cell-wall bound calcium content. Compared to normal freezing, the values of textural properties, color, L-ascorbic acid content were better preserved and the drip loss was significantly minimized by the application of UAF. However, when outside that range of acoustic intensity, the quality of the ultrasound-assisted frozen broccoli was inferior compared to that of the normally frozen samples. Selected the appropriate acoustic intensity was very important for the application of UAF. Copyright © 2014 Elsevier B.V. All rights reserved.
Survival differences among freeze-dried genetically engineered and wild-type bacteria.
Israeli, E; Shaffer, B T; Hoyt, J A; Lighthart, B; Ganio, L M
1993-01-01
Because the death mechanisms of freeze-dried and air-dried bacteria are thought to be similar, freeze-drying was used to investigate the survival differences between potentially airborne genetically engineered microorganisms and their wild types. To this end, engineered strains of Escherichia coli and Pseudomonas syringae were freeze-dried and exposed to air, visible light, or both. The death rates of all engineered strains were significantly higher than those of their parental strains. Light and air exposure were found to increase the death rates of all strains. Application of death rate models to freeze-dried engineered bacteria to be released into the environment is discussed. PMID:8434925
Dendrimer-Linked Antifreeze Proteins Have Superior Activity and Thermal Recovery.
Stevens, Corey A; Drori, Ran; Zalis, Shiran; Braslavsky, Ido; Davies, Peter L
2015-09-16
By binding to ice, antifreeze proteins (AFPs) depress the freezing point of a solution and inhibit ice recrystallization if freezing does occur. Previous work showed that the activity of an AFP was incrementally increased by fusing it to another protein. Even larger increases in activity were achieved by doubling the number of ice-binding sites by dimerization. Here, we have combined the two strategies by linking multiple outward-facing AFPs to a dendrimer to significantly increase both the size of the molecule and the number of ice-binding sites. Using a heterobifunctional cross-linker, we attached between 6 and 11 type III AFPs to a second-generation polyamidoamine (G2-PAMAM) dendrimer with 16 reactive termini. This heterogeneous sample of dendrimer-linked type III constructs showed a greater than 4-fold increase in freezing point depression over that of monomeric type III AFP. This multimerized AFP was particularly effective at ice recrystallization inhibition activity, likely because it can simultaneously bind multiple ice surfaces. Additionally, attachment to the dendrimer has afforded the AFP superior recovery from heat denaturation. Linking AFPs together via polymers can generate novel reagents for controlling ice growth and recrystallization.
Peterson, Daniel S; King, Laurie A; Cohen, Rajal G; Horak, Fay B
2016-05-01
People with Parkinson disease (PD) who show freezing of gait also have dysfunction in cognitive domains that interact with mobility. Specifically, freezing of gait is associated with executive dysfunction involving response inhibition, divided attention or switching attention, and visuospatial function. The neural control impairments leading to freezing of gait have recently been attributed to higher-level, executive and attentional cortical processes involved in coordinating posture and gait rather than to lower-level, sensorimotor impairments. To date, rehabilitation for freezing of gait primarily has focused on compensatory mobility training to overcome freezing events, such as sensory cueing and voluntary step planning. Recently, a few interventions have focused on restitutive, rather than compensatory, therapy. Given the documented impairments in executive function specific to patients with PD who freeze and increasing evidence of overlap between cognitive and motor function, incorporating cognitive challenges with mobility training may have important benefits for patients with freezing of gait. Thus, a novel theoretical framework is proposed for exercise interventions that jointly address both the specific cognitive and mobility challenges of people with PD who freeze. © 2016 American Physical Therapy Association.
[The phenomenology of depression].
Lammel, M
1987-06-01
Jakob Wassermann's story Die Gefangenen auf der Plassenburg (The prisoners of Plasenburg) is taken as a starting point for a discussion of experiences, coping with events, and estrangement, and their effect regarding depressive emotional deterioration and its description. The possibilities of succinct expression in the description of boredom, depressive emotional deterioration, melancholy, and dejection are indicated, with special reference to interactional psychopathology.
Generalized Dynamic Equations Related to Condensation and Freezing Processes
NASA Astrophysics Data System (ADS)
Wang, Xingrong; Huang, Yong
2018-01-01
The generalized thermodynamic equation related to condensation and freezing processes was derived by introducing the condensation and freezing probability function into the dynamic framework based on the statistical thermodynamic fluctuation theory. As a result, the physical mechanism of some weather phenomena covered by using
Yang, Chun-Yu; Guo, Feng-Qian; Zang, Chen; Cao, Hui; Zhang, Bao-Xian
2018-02-01
Ginger juice, a commonly used adjuvant for Chinese materia medica, is applied in processing of multiple Chinese herbal decoction pieces. Because of the raw materials and preparation process of ginger juice, it is difficult to be preserved for a long time, and the dosage of ginger juice in the processing can not be determined base on its content of main compositions. Ginger juice from different sources is hard to achieve consistent effect during the processing of traditional Chinese herbal decoction pieces. Based on the previous studies, the freeze drying of ginger juice under different shelf temperatures and vacuum degrees were studied, and the optimized freeze drying condition of ginger juice was determined. The content determination method for 6-gingerol, 8-gingerol, 10-gingerol and 6-shagaol in ginger juice and redissolved ginger juice was established. The content changes of 6-gingerol, 8-gingerol, 10-gingerol, 6-gingerol, 6-shagaol, volatile oil and total phenol were studied through the drying process and 30 days preservation period. The results showed that the freeze drying time of ginger juice was shortened after process optimization; the compositions basically remained unchanged after freeze drying, and there was no significant changes in the total phenol content and gingerol content, but the volatile oil content was significantly decreased( P <0.05). Within 30 days, the contents of gingerol, total phenol, and volatile oil were on the decline as a whole. This study has preliminarily proved the feasibility of freeze-drying process of ginger juice as an adjuvant for Chinese medicine processing. Copyright© by the Chinese Pharmaceutical Association.
Thermomechanical analysis of freezing-induced cell-fluid-matrix interactions in engineered tissues
Han, Bumsoo; Teo, Ka Yaw; Ghosh, Soham; Dutton, J. Craig; Grinnell, Frederick
2012-01-01
Successful cryopreservation of functional engineered tissues (ETs) is significant to tissue engineering and regenerative medicine, but it is extremely challenging to develop a successful protocol because the effects of cryopreservation parameters on the post-thaw functionality of ETs are not well understood. Particularly, the effects on the microstructure of their extracellular matrix (ECM) have not been well studied, which determines many functional properties of the ETs. In this study, we investigated the effects of two key cryopreservation parameters – i) freezing temperature and corresponding cooling rate; and ii) the concentration of cryoprotective agent (CPA) on the ECM microstructure as well as the cellular viability. Using dermal equivalent as a model ET and DMSO as a model CPA, freezing-induced spatiotemporal deformation and post-thaw ECM microstructure of ETs was characterized while varying the freezing temperature and DMSO concentrations. The spatial distribution of cellular viability and the cellular actin cytoskeleton was also examined. The results showed that the tissue dilatation increased significantly with reduced freezing temperature (i.e., rapid freezing). A maximum limit of tissue deformation was observed for preservation of ECM microstructure, cell viability and cell-matrix adhesion. The dilatation decreased with the use of DMSO, and a freezing temperature dependent threshold concentration of DMSO was observed. The threshold DMSO concentration increased with lowering freezing temperature. In addition, an analysis was performed to delineate thermodynamic and mechanical components of freezing-induced tissue deformation. The results are discussed to establish a mechanistic understanding of freezing-induced cell-fluid-matrix interaction and phase change behavior within ETs in order to improve cryopreservation of ETs. PMID:23246556
Xu, Hong-Xia; Li, Xiao-Ying; Chen, Jun-Wei
2017-09-01
Loquat (Eriobotrya japonica Lindl.) is an important subtropical, commercial fruit in China. It blossoms during autumn and winter in most areas of China and its fruitlets usually suffer from freezing stress. However, studies about the mechanisms underlying freezing stress in loquat are very limited. The gene expression profiles of loquat fruitlets subjected to freezing (G2 library) versus non-treated ones (G1 library) were investigated using Illumina sequencing technology to elucidate the molecular mechanisms and identify the genes that play vital roles in the freezing stress response. The results showed that approximately 157.63 million reads in total were obtained from freeze-treated and non-treated loquat fruitlets. These reads were assembled into 87,379 unigenes with an average length of 710 bp and an N50 of 1,200 bp. After comparing the profiles obtained from the G1 and G2 libraries, 2,892 differentially expressed genes were identified, of which 1,883 were up-regulated and 1,009 were down-regulated in the treated samples compared to non-treated ones. These unigenes showed significant differences in expression for carbohydrate transport and metabolism, amino acid metabolism, energy metabolism, and lipid metabolism, which are involved in defense against freezing stress. Glycolysis/gluconeogenesis was one of the most significantly regulated pathways. Freezing also significantly damaged the membrane system of loquat fruitlets, and several defense mechanisms were induced. Some selected genes related to low temperature resistance were validated by quantitative real-time PCR (qRT-PCR). The results revealed many genes and pathways that are part of freezing resistance processes and expand our understanding of the complex molecular events involved in freezing stress.
Handwriting Impairments in People With Parkinson's Disease and Freezing of Gait.
Heremans, Elke; Nackaerts, Evelien; Broeder, Sanne; Vervoort, Griet; Swinnen, Stephan P; Nieuwboer, Alice
2016-11-01
Recent studies show that patients with Parkinson's disease (PD) and freezing of gait (FOG) experience motor problems outside their gait freezing episodes. Because handwriting is also a sequential movement, it may be affected in PD patients with FOG relative to those without. The current study aimed to assess the quality of writing in PD patients with and without FOG in comparison to healthy controls (CTs) during various writing tasks. Handwriting was assessed by the writing of cursive loops on a touch-sensitive writing tablet and by means of the Systematic Screening of Handwriting Difficulties (SOS) test in 30 PD patients with and without freezing and 15 healthy age-matched CTs. The tablet tests were performed at 2 different sizes, either continuously or alternatingly, as indicated by visual target lines. Patients with freezing showed decreased writing amplitudes and increased variability compared with CTs and patients without freezing on the writing tablet tests. Writing problems were present during both tests but were more pronounced during writing at alternating compared with writing at continuous size. Patients with freezing also had a higher total score on the SOS test than patients without freezing and CTs, reflecting more extensive handwriting problems, particularly with writing fluency. Writing is more severely affected in PD patients with FOG than in those without FOG. These results indicate that deficient movement sequencing and adaptation is a generic problem in patients with FOG. © The Author(s) 2016.
Kamiya, Seitaro; Nakashima, Kenichiro
2017-12-01
Nanoparticle suspensions are thermodynamically unstable and subject to aggregation. Freeze-drying on addition of saccharides is a useful method for preventing aggregation. In the present study, tetrasaccharides (stachyose) was employed as an additive. In addition, we hypothesize the interactive mechanism between stachyose and the nanoparticles during freeze-drying for the first time. The mean particle size of the rehydrated freeze-dried stachyose-containing nanoparticles (104.7 nm) was similar to the initial particle size before freeze-drying (76.8 nm), indicating that the particle size had been maintained. The mean particle size of the rehydrated normal-dried stachyose-containing nanoparticles was 222.2 nm. The powder X-ray diffraction of the freeze-dried stachyose-containing nanoparticles revealed a halo pattern. The powder X-ray diffraction of the normally dried stachyose-containing nanoparticles produced mainly a halo pattern and a partial peak. These results suggest an interaction between the nanoparticles and stachyose, and that this relationship depends on whether the mixture is freeze-dried or dried normally. In the case of normal drying, although most molecules cannot move rapidly thereby settling irregularly, some stachyose molecules can arrange regularly leading to some degree of crystallization and potentially some aggregation. In contrast, during freeze-drying, the moisture sublimed, while the stachyose molecules and nanoparticles were immobilized in the ice. After sublimation, stachyose remained in the space occupied by water and played the role of a buffer material, thus preventing aggregation.
Migration of Water in Litopenaeus Vannamei Muscle Following Freezing and Thawing.
Deng, Qi; Wang, Yaling; Sun, Lijun; Li, Jianrong; Fang, Zhijia; Gooneratne, Ravi
2018-06-15
Water and protein are major constituents of shrimp, any changes in protein and the state of water influence the quality of shrimp. Therefore, a study to examine the law of moisture migration and protein denaturation under different freezing and thawing conditions is important. The proton density images of thawed frozen-shrimp revealed that the water loss during quick-freezing was much greater than that during slow freezing or microfreezing. At room temperature (25 °C), the water loss from brine-thawing was more than still-water thawing and still-water thawing was more than thawing spontaneously. Freezing-thawing resulted in uniform water redistribution in shrimp muscle. Nuclear magnetic resonance technology (low field magnetic imaging) was used to directly monitor the dynamic processes of fluidity state in shrimp and indirectly monitor protein denaturation and thereby determine the optimal method of freezing-thawing shrimp. Our research showed that microfreezing preservation minimized weight loss, juice leakage and protein denaturation in shrimp muscle during thawing. Water is one of the major components in most organs and is an important factor that influences the shrimp muscle quality. Water migration patterns and subsequent effects on the shrimp muscle under different freezing and thawing conditions were examined using low field nuclear magnetic resonance (NMR) technology. This research provides a theoretical foundation for shrimp processing plants to improve the freezing and thawing process to obtain optimal quality and flavor of shrimp products. © 2018 Institute of Food Technologists®.
The physico-chemical basis for the freeze-drying process.
MacKenzie, A P
1976-10-01
To the extent that the final form and quality of a freeze-dried product depends on the way the freeze-drying is conducted, an understanding of the many factors involved is most important. The numerous effects of the design and mode of operation of the freeze-drying equipment on the course of the process need to be known, as do the properties intrinsic to the material to be freeze-dried. Much can be learned and predicted from the study of the "supplemented phase diagram", a series of experimental plots describing the equilibrium and the non-equilibrium phase behavior of the system in question. Such diagrams map and distinguish eutectic and amorphous phase behavior. Further information is available from gravimetric studies allowing the construction of "desorption isotherms", the plots describing the loss of sorbed water accompanying the sublimation of ice, frequently termed "secondary drying". These plots relate the water retained by the product to the "water activity", or relative humidity at different temperatures. Observations in the freeze-drying microscope contribute additional information, in that they reveal the actual course of the process at the microscopic level. These and other laboratory findings facilitate the analysis and comparison of pilot-plant and commercical scale processing experiences. Where scientific and engineering factors appear to interrelate, the nature and extent of the interdependence can often be determined.
Freeze Tolerance of Seed-Producing Turf Bermudagrasses.
Anderson, Jeffrey A.; Taliaferro, Charles M.
2002-01-01
Bermudagrass, Cynodon dactylon (L.) Pers., suffers periodic severe winter-kill throughout much of its area of use in the contiguous USA. A research goal is to increase freeze tolerance in cultivars to lessen the risk of such damage. An identified research need is for Cynodon germplasm resources to be characterized for freeze tolerance and hybridization potential. Accordingly, the objective of this research was to characterize the relative freeze tolerance of selected fertile bermudagrass plants. Nine tetraploid (2n = 4x = 36) C. dactylon and two triploid (2n = 3x = 27) hybrid (C. dactylon x C. transvaalensis Burtt Davy) clonal plants (standards) were evaluated in two experiments. Plants were propagated clonally and established in Cone-tainers (Ray Leach Cone-tainer Nursery, Canby, OR) for about 10 wk. Acclimation took place for 4 wk in controlled environment chambers at 8/2 degrees C (day/night) temperatures with a 10-h photoperiod. Following acclimation, Cone-tainers were placed into a freeze chamber and cooled rapidly to -2 degrees C, induced to freeze with ice chips, then held overnight at -2 degrees C. The freeze chamber was then programmed to cool linearly at 1 degrees C per hour. For each cultivar, three Cone-tainers were removed at each test temperature. Following thawing, Cone-tainers were transferred to a greenhouse and regrowth was evaluated visually. Nonlinear regression was used to estimate T(mid), which corresponded to the midpoint of the sigmoidal response curve of survival vs temperature. Within experiment one, Tifgreen (T(mid) = -7.2 degrees C) was significantly less cold hardy than Quickstand (-9.0 degrees C), A-12204 (-9.2 degrees C), Midiron (-9.9 degrees C), and A-12195 (-10.5 degrees C). A-12195 was significantly hardier than all genotypes except Midiron. In the second experiment, Arizona Common (-6.6 degrees C), Tifgreen (-7.1 degrees C), and A-12205 (-7.1 degrees C) were less hardy than A-9959 (-8.7 degrees C), A-12156 (-8.9 degrees C), A
Validation of the shake test for detecting freeze damage to adsorbed vaccines.
Kartoglu, Umit; Ozgüler, Nejat Kenan; Wolfson, Lara J; Kurzatkowski, Wiesław
2010-08-01
To determine the validity of the shake test for detecting freeze damage in aluminium-based, adsorbed, freeze-sensitive vaccines. A double-blind crossover design was used to compare the performance of the shake test conducted by trained health-care workers (HCWs) with that of phase contrast microscopy as a "gold standard". A total of 475 vials of 8 different types of World Health Organization prequalified freeze-sensitive vaccines from 10 different manufacturers were used. Vaccines were kept at 5 degrees C. Selected numbers of vials from each type were then exposed to -25 degrees C and -2 degrees C for 24-hour periods. There was complete concordance between HCWs and phase-contrast microscopy in identifying freeze-damaged vials and non-frozen samples. Non-frozen samples showed a fine-grain structure under phase contrast microscopy, but freeze-damaged samples showed large conglomerates of massed precipitates with amorphous, crystalline, solid and needle-like structures. Particles in the non-frozen samples measured from 1 microm (vaccines against diphtheria-tetanus-pertussis; Haemophilus influenzae type b; hepatitis B; diphtheria-tetanus-pertussis-hepatitis B) to 20 microm (diphtheria and tetanus vaccines, alone or in combination). By contrast, aggregates in the freeze-damaged samples measured up to 700 microm (diphtheria-tetanus-pertussis) and 350 microm on average. The shake test had 100% sensitivity, 100% specificity and 100% positive predictive value in this study, which confirms its validity for detecting freeze damage to aluminium-based freeze-sensitive vaccines.
Experience Modulates Vicarious Freezing in Rats: A Model for Empathy
Atsak, Piray; Orre, Marie; Bakker, Petra; Cerliani, Leonardo; Roozendaal, Benno
2011-01-01
The study of the neural basis of emotional empathy has received a surge of interest in recent years but mostly employing human neuroimaging. A simpler animal model would pave the way for systematic single cell recordings and invasive manipulations of the brain regions implicated in empathy. Recent evidence has been put forward for the existence of empathy in rodents. In this study, we describe a potential model of empathy in female rats, in which we studied interactions between two rats: a witness observes a demonstrator experiencing a series of footshocks. By comparing the reaction of witnesses with or without previous footshock experience, we examine the role of prior experience as a modulator of empathy. We show that witnesses having previously experienced footshocks, but not naïve ones, display vicarious freezing behavior upon witnessing a cage-mate experiencing footshocks. Strikingly, the demonstrator's behavior was in turn modulated by the behavior of the witness: demonstrators froze more following footshocks if their witness froze more. Previous experiments have shown that rats emit ultrasonic vocalizations (USVs) when receiving footshocks. Thus, the role of USV in triggering vicarious freezing in our paradigm is examined. We found that experienced witness-demonstrator pairs emitted more USVs than naïve witness-demonstrator pairs, but the number of USVs was correlated with freezing in demonstrators, not in witnesses. Furthermore, playing back the USVs, recorded from witness-demonstrator pairs during the empathy test, did not induce vicarious freezing behavior in experienced witnesses. Thus, our findings confirm that vicarious freezing can be triggered in rats, and moreover it can be modulated by prior experience. Additionally, our result suggests that vicarious freezing is not triggered by USVs per se and it influences back onto the behavior of the demonstrator that had elicited the vicarious freezing in witnesses, introducing a paradigm to study empathy
Microplate freeze-dried cyanobacterial bioassay for fresh-waters environmental monitoring.
Martín-Betancor, Keila; Durand, Marie-José; Thouand, Gérald; Leganés, Francisco; Fernández-Piñas, Francisca; Rodea-Palomares, Ismael
2017-12-01
Microorganisms have been very useful in environmental monitoring due to their constant sensing of the surrounding environment, their easy maintenance and low cost. Some freeze-dried toxicity kits based on naturally bioluminescent bacteria are commercially available and commonly used to assess the toxicity of environmental samples such as Microtox (Aliivibrio fischeri) or ToxScreen (Photobacterium leiognathi), however, due to the marine origin of these bacteria, they could not be the most appropriate for fresh-waters monitoring. Cyanobacteria are one of the most representative microorganisms of aquatic environments, and are well suited for detecting contaminants in aqueous samples. This study presents the development and application of the first freeze-dried cyanobacterial bioassay for fresh-water contaminants detection. The effects of different cell growth phases, cryoprotectant solutions, freezing protocols, rehydration solutions and incubation conditions methods were evaluated and the best combination of these parameters for freeze-drying was selected. The study includes detailed characterization of sensitivity towards reference pollutants, as well as, comparison with the standard assays. Moreover, long-term viability and sensitivity were evaluated after 3 years of storage. Freeze-dried cyanobacteria showed, in general, higher sensitivity than the standard assays and viability of the cells remained after 3 years of storage. Finally, the validation of the bioassay using a wastewater sample was also evaluated. Freeze-drying of cyanobacteria in 96-well plates presents a simple, fast and multi-assay method for environmental monitoring. Copyright © 2017 Elsevier Ltd. All rights reserved.
Effect of Repeated Freeze-Thaw Cycles on Beef Quality and Safety
Rahman, Mohammad Hafizur; Hossain, Mohammad Mujaffar; Rahman, Syed Mohammad Ehsanur; Hashem, Mohammad Abul
2014-01-01
The objectives of this study were to know the effect of repeated freeze-thaw cycles of beef on the sensory, physicochemical quality and microbiological assessment. The effects of three successive freeze-thaw cycles on beef forelimb were investigated comparing with unfrozen fresh beef for 75 d by keeping at −20±1℃. The freeze-thaw cycles were subjected to three thawing methods and carried out to know the best one. As the number of freeze-thaw cycles increased color and odor declined significantly before cook within the cycles and tenderness, overall acceptability also declined among the cycles after cook by thawing methods. The thawing loss increased and dripping loss decreased significantly (p<0.05). Water holding capacity (WHC) increased (p<0.05) until two cycles and then decreased. Cooking loss increased in cycle 1 and 3, but decreased in cycle 2. pH decreased significantly (p<0.05) among the cycles. Moreover, drip loss, cooking loss and WHC were affected (p<0.05) by thawing methods within the cycles. 2-Thiobarbituric acid (TBARS) value increased (p<0.05) gradually within the cycles and among the cycles by thawing methods. Total viable bacteria, total coliform and total yeast-mould count decreased significantly (p<0.05) within and among the cycles in comparison to the initial count in repeated freeze-thaw cycles. As a result, repeated freeze-thaw cycles affected the sensory, physicochemical and microbiological qua- lity of beef, causing the deterioration of beef quality, but improved the microbiological quality. Although repeated freeze-thaw cycles did not affect much on beef quality and safety but it may be concluded that repeated freeze and thaw should be minimized in terms of beef color for commercial value and WHC and tenderness/juiciness for eating quality. PMID:26761286
Stress, deformation and micromorphological aspects of soil freezing under laboratory conditions
NASA Astrophysics Data System (ADS)
Jetchick, Elizabeth
In this thesis, frost heave is viewed as a process resulting from the interactions between thermodynamic conditions, soil environment controls such as texture, stress/deformation conditions and soil microstructure. A series of laboratory experiments was devised to investigate the links between these aspects. Because a limited number of studies exist on the development of internal stresses and strains in freezing soil, the work focussed on obtaining rheological data using conventional soil strain gauges and prototype stress transducers. A fine-grained unstructured silt was placed in a column (30 cm diameter by 100 cm length) and subjected to freezing and freeze-thaw cycles from the top down, lasting up to three months. Heat and water flows, as well as stresses and strains were monitored. The frozen soil was sectioned at the end of four of the experiments to examine the soil fabrics that had developed. From the experimental results, schematic stress and strain curves are proposed. For a single freeze cycle, compressive normal and tensile normal stresses were recorded simultaneously by the measuring devices within the freezing soil profile. Ice lens inception took place when the stress field changed, a condition which occurred either at the frost front level or at the base of the growing ice lens. Negative and positive strains reflected the different stress states that were sustained below and above the freezing front. Negative strains or soil consolidation took place as stresses increased before the passage of the frost line. Negligible soil strains were recorded as maximum soil consolidation was attained, before soil expansion. Distinct positive strain patterns indicating secondary and continuing heave, were recorded simultaneously throughout a thickness of soil, over a range of temperatures. Ice lens growth mostly took place as secondary frost heave, but continuing heave was measured, and the temperature conditions for both types of heave were determined. During
The 2007 California Citrus Freeze: Vulnerability, Poverty, and Unemployment Issues of Farmworkers
ERIC Educational Resources Information Center
Orozco, Graciela Leon
2010-01-01
In January of 2007, freezing temperatures destroyed citrus and vegetable crops in California. By May 2007, more than 9,000 freeze-related unemployment applications had been fled. Through face-to-face interviews, this study documents the experience of 63 farmworkers to find out how they survived the freeze and accessed services. Findings revealed…
Effect of demedullation on freezing injury in hind limbs of rats
NASA Astrophysics Data System (ADS)
Dhingra, Shashi; Bhatia, B.; Chhina, G. S.; Singh, Baldev
1987-09-01
Freezing incidence and tissue loss on exposure of hind limbs of female Wistar rats to freezing mixture was reduced by demedullation 6 days prior to cold exposure (p<0.01 and p<0.001 respectively); demedullation 1 h after freezing injury had no effect on tissue loss. Noradrenaline (1 mg/kg i.p.) 5 min before exposure increased the freezing incidence in intact (p<0.05) as well as in demedullated rats (p<0.01), with no effect on tissue loss. Adrenaline (500 mg/kg i.p.) had no effect on either. A sustained fall in plasma adrenaline after demedullation leading to reduced reactivity of the blood vessels to some vasoactive agents is postulated.
Role of cells in freezing-induced cell-fluid-matrix interactions within engineered tissues.
Seawright, Angela; Ozcelikkale, Altug; Dutton, Craig; Han, Bumsoo
2013-09-01
During cryopreservation, ice forms in the extracellular space resulting in freezing-induced deformation of the tissue, which can be detrimental to the extracellular matrix (ECM) microstructure. Meanwhile, cells dehydrate through an osmotically driven process as the intracellular water is transported to the extracellular space, increasing the volume of fluid for freezing. Therefore, this study examines the effects of cellular presence on tissue deformation and investigates the significance of intracellular water transport and cell-ECM interactions in freezing-induced cell-fluid-matrix interactions. Freezing-induced deformation characteristics were examined through cell image deformetry (CID) measurements of collagenous engineered tissues embedded with different concentrations of MCF7 breast cancer cells versus microspheres as their osmotically inactive counterparts. Additionally, the development of a biophysical model relates the freezing-induced expansion of the tissue due to the cellular water transport and the extracellular freezing thermodynamics for further verification. The magnitude of the freezing-induced dilatation was found to be not affected by the cellular water transport for the cell concentrations considered; however, the deformation patterns for different cell concentrations were different suggesting that cell-matrix interactions may have an effect. It was, therefore, determined that intracellular water transport during freezing was insignificant at the current experimental cell concentrations; however, it may be significant at concentrations similar to native tissue. Finally, the cell-matrix interactions provided mechanical support on the ECM to minimize the expansion regions in the tissues during freezing.
2010-01-01
Background Freezing is an increasingly important means of preservation and storage of microbial strains used for many types of industrial applications including food processing. However, the yeast mechanisms of tolerance and sensitivity to freeze or near-freeze stress are still poorly understood. More knowledge on this regard would improve their biotechnological potential. Glycerol, in particular intracellular glycerol, has been assigned as a cryoprotectant, also important for cold/near-freeze stress adaptation. The S. cerevisiae glycerol active transporter Stl1p plays an important role on the fast accumulation of glycerol. This gene is expressed under gluconeogenic conditions, under osmotic shock and stress, as well as under high temperatures. Results We found that cells grown on STL1 induction medium (YPGE) and subjected to cold/near-freeze stress, displayed an extremely high expression of this gene, also visible at glycerol/H+ symporter activity level. Under the same conditions, the strains harbouring this transporter accumulated more than 400 mM glycerol, whereas the glycerol/H+ symporter mutant presented less than 1 mM. Consistently, the strains able to accumulate glycerol survive 25-50% more than the stl1Δ mutant. Conclusions In this work, we report the contribution of the glycerol/H+ symporter Stl1p for the accumulation and maintenance of glycerol intracellular levels, and consequently cell survival at cold/near-freeze and freeze temperatures. These findings have a high biotechnological impact, as they show that any S. cerevisiae strain already in use can become more resistant to cold/freeze-thaw stress just by simply adding glycerol to the broth. The combination of low temperatures with extracellular glycerol will induce the transporter Stl1p. This solution avoids the use of transgenic strains, in particular in food industry. PMID:21047428
Protein spheres prepared by drop jet freeze drying.
Eggerstedt, Sören N; Dietzel, Mathias; Sommerfeld, Martin; Süverkrüp, Richard; Lamprecht, Alf
2012-11-15
In spray freeze drying (SFD) solutions are frozen by spraying into a very cold environment and subsequently dried by sublimation. In contrast to conventional freeze drying, spray freeze drying has the possibility to produce flowable lyophilizates which offers a variety of new pharmaceutical applications. Here, a drop jet nozzle is proposed as liquid dispenser that is able to produce droplets with a very narrow size distribution compared to standard methods. The drop jet nozzle is mounted in a spray tower designed to prevent direct contact of the product with the freezing medium. Various formulations have been tested containing lysozyme as model protein and stabilizers such as bovine serum albumin, polyvinylpyrrolidone or dextran in various concentrations and mannitol. Excellent free flowing and nearly monodispersed, porous particles are produced where particle properties can be controlled by formulation and process conditions. The particle diameter varied between 231 ± 3 μm and 310 ± 10 μm depending on the formulation composition. The lysozyme activity was >94 ± 5% for all formulations exhibiting a full preservation of enzyme activity. This new method is very promising for the production of nearly monodisperse particulate lyophilizates in various therapeutic applications. Copyright © 2012 Elsevier B.V. All rights reserved.
A New Freezing Method Using Pre-Dehydration by Microwave-Vacuum Drying
NASA Astrophysics Data System (ADS)
Tsuruta, Takaharu; Hamidi, Nurkholis
Partial dehydration by microwave-vacuum drying has been applied to tuna and strawberry in order to reduce cell-damages caused by the formation of large ice-crystals during freezing. The samples were subjected to microwave vacuum drying at pressure of 5 kPa and temperature less than 27°C to remove small amount of water prior to freezing. The tuna were cooled by using the freezing chamber at temperature -50°C or -150°C, while the strawberries were frozen at temperature -30°C or -80°C, respectively. The temperature transients in tuna showed that removing some water before freezing made the freezing time shorter. The observations of ice crystal clearly indicated that rapid cooling and pre-dehydration prior to freezing were effective in minimizing the size of ice crystal. It is also understood that the formation of large ice crystals has a close relation to the cell damages. After thawing, the observation of microstructure was done on the tuna and strawberry halves. The pre-dehydrated samples showed a better structure than the un-dehydrated one. It is concluded that the pre-dehydration by microwave-vacuum drying is one promising method for the cryo-preservation of foods.
Toward intradermal vaccination: preparation of powder formulations by collapse freeze-drying.
Etzl, Elsa E; Winter, Gerhard; Engert, Julia
2014-03-01
Intradermal powder immunization is an emerging technique in vaccine delivery. The purpose of this study was to generate powder particles for intradermal injection by freeze-drying and subsequent cryo-milling. Two different freeze-drying protocols were compared, a moderate freeze-drying cycle and an aggressive freeze-drying cycle, which induced a controlled collapse of the sugar matrix. Ovalbumin served as model antigen. The influence of collapse drying and cryo-milling on particle morphology and protein stability was investigated. Cryo-milling generated irregularly shaped particles of size 20-70 µm. The recovery of soluble monomer of ovalbumin was not changed during freeze-drying and after cryo-milling, or after 12 months of storage at 2-8 °C. A slight increase in higher molecular weight aggregates was found in formulations containing the polymer dextran after 12 months of storage at 50 °C. Light obscuration measurements showed an increase in cumulative particle counts after cryo-milling that did not further increase during storage at 2-8 °C for 12 months. The applicability of the cryo-milling process to other therapeutic proteins was shown using recombinant human granulocyte-colony stimulating factor. Collapse freeze-drying and subsequent cryo-milling allows the generation of particles suitable for intradermal powder injection.
Destabilization of mayonnaise induced by lipid crystallization upon freezing.
Miyagawa, Yayoi; Ogawa, Takenobu; Nakagawa, Kyuya; Adachi, Shuji
2016-01-01
The thermal and rheological history of mayonnaise during freezing and its dispersion stability after the freeze-thaw process were investigated. Mayonnaise was cooled to freeze and stored at -20 to -40 °C while monitoring the temperature; penetration tests were conducted on the mayonnaise, which was sampled at selected times during isothermal storage at -20 °C. Significant increases in the temperature and stress values due to water-phase crystallization and subsequent oil-phase crystallization were observed. The water phase crystallized during the cooling step in all the tested mayonnaise samples. The oil phases of the prepared mayonnaise (with rapeseed oil) and commercial mayonnaise crystallized during isothermal storage after 6 and 4 h, respectively, at -20 °C. The dispersion stability was evaluated from the separation ratio, which was defined as the weight ratio of separated oil after centrifuging to the total amount of oil in the commercial mayonnaise. The separation ratio rapidly increased after 4 h of freezing. This result suggests that crystallization of the oil phase is strongly related to the dispersion stability of mayonnaise.
Monitoring Freeze Injury and Evaluating Losingto Sugar-Cane Using RS and GPS
NASA Astrophysics Data System (ADS)
Tan, Zongkun; Ding, Meihua; Wang, Longhe; Yang, Xin; Ou, Zhaorong
From Jan 12th to Feb 12th 2008, the most severity cold chilling and freeze injury weather took place during the last 50 years in the southern of China.Sugar-cane was suffered injury severity. However, the losing of sugar-cane which it was aroused by thisweather disaster had not been exactitude evaluated till on Apr 1st, 2008. It was not only affected the sugar-cane ordinary harvesting and crushing, but also affected reserving sugar-cane seed for planting. Freeze injury is common disaster for sugar-cane in southern of China and monitoring freeze injury using RS and GIS are of great economic significance but little research work about it has been done in China Freeze injuring is not only related to crop growth stage and the cold air intension from northern to southern and weather types, but also consanguineous related to land form and physiognomy and geographical latitude and height above sea level etc and crop planting spatial distribution. The case study of Guangxi province which is the biggest region of sugar-cane planting in China in this paper, the values of sugar-cane NDVI among the freeze injury occur former and after in early 2008 and without freeze injury occur in the same term 2007 were analyzed and compared based on the sugar-cane planting spatial distribution information which were carried out by using multi-phase EOS/MODIS data. The result showed that it was not only commendably reflected the spatial distribution of freeze injury but also reflected the sugarcane suffered from degree using the values of sugar-cane NDVIof freeze injury occur former and after. The field sample investigation data of using GPS was integrated with the NDVI, the evaluation of region sugar-cane suffer from freeze injury losing could quickly and exactly realize.
Gelatin-Filtered Consomme: A Practical Demonstration of the Freezing and Thawing Processes
ERIC Educational Resources Information Center
Lahne, Jacob B.; Schmidt, Shelly J.
2010-01-01
Freezing is a key food processing and preservation technique widely used in the food industry. Application of best freezing and storage practices extends the shelf-life of foods for several months, while retaining much of the original quality of the fresh food. During freezing, as well as its counterpart process, thawing, a number of critical…
NASA Astrophysics Data System (ADS)
Eckerstorfer, M.; Malnes, E.; Christiansen, H. H.
2017-09-01
In periglacial landscapes, snow dynamics and microtopography have profound implications of freeze-thaw conditions and thermal regime of the ground. We mapped periglacial landforms at Kapp Linné, central Svalbard, where we chose six widespread landforms (solifluction sheet, nivation hollow, palsa and peat in beach ridge depressions, raised marine beach ridge, and exposed bedrock ridge) as study sites. At these six landforms, we studied ground thermal conditions, freeze-thaw cycles, and snow dynamics using a combination of in situ monitoring and C-band radar satellite data in the period 2005-2012. Based on these physical parameters, the six studied landforms can be classified into raised, dry landforms with minor ground ice content and a thin, discontinuous snow cover and into wet landforms with high ice content located in the topographical depressions in-between with medium to thick snow cover. This results in a differential snow-melting period inferred from the C-band radar satellite data, causing the interseasonal and interlandform variability in the onset of ground surface thawing once the ground becomes snow free. Therefore, variability also exists in the period of thawed ground surface conditions. However, the length of the season with thawed ground surface conditions does not determine the mean annual ground surface temperature, it only correlates well with the active layer depths. From the C-band radar satellite data series, measured relative backscatter trends hint toward a decrease in snow cover through time and a more frequent presence of ice layers from mid-winter rain on snow events at Kapp Linné, Svalbard.
Colder freeze-in axinos decaying into photons
NASA Astrophysics Data System (ADS)
Bae, Kyu Jung; Kamada, Ayuki; Liew, Seng Pei; Yanagi, Keisuke
2018-03-01
We point out that 7 keV axino dark matter (DM) in the R-parity violating (RPV) supersymmetric (SUSY) Dine-Fischler-Srednicki-Zhitnitsky axion model can simultaneously reproduce the 3.5 keV x-ray line excess and evade stringent constraints from the Ly -α forest data. Peccei-Quinn symmetry breaking naturally generates both the TeV-scale μ term and the MeV-scale RPV term. The RPV term introduces a tiny axino-neutrino mixing and provides axino DM as a variant of the sterile neutrino DM explaining the 3.5 keV x-ray line excess. Axinos are produced by freeze-in processes via the μ term. The resultant phase space distribution tends to be colder than the Fermi-Dirac distribution. The inherent entropy production from late-time saxion decay makes axinos even colder than those without saxion decay. The resultant axino DM takes the correct relic density and is compatible even with the latest and strongest constraint from the Ly-α forest data.
Ice nucleation temperature influences recovery of activity of a model protein after freeze drying.
Cochran, Teresa; Nail, Steven L
2009-09-01
The objective of this study was to determine whether a relationship exists between ice nucleation temperature and recovery of activity of a model protein, lactate dehydrogenase, after freeze drying. Aqueous buffer systems containing 50 microg/mL of protein were frozen in vials with externally mounted thermocouples on the shelf of a freeze dryer, then freeze dried. Various methods were used to establish a wide range of ice nucleation temperatures. An inverse relationship was found between the extent of supercooling during freezing and recovery of activity in the reconstituted solution. The data are consistent with a mechanism of inactivation resulting from adsorption of protein at the ice/freeze-concentrate interface during the freezing process.
Numerical study of the effect of the shape of the phase diagram on the eutectic freezing temperature
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ode, M.; Shimono, M.; Sasajima, N.
2013-09-11
To evaluate the reliability of metal-carbon eutectic systems as fixed points for the next generation of high-temperature standards the effect of thermodynamic properties related to the shape of eutectic phase diagram on the freezing temperature is investigated within the context of the numerical multi-phase-field model. The partition coefficient and liquidus slopes of the two solids involved in the eutectic reaction are varied deliberately and independently. The difference between the eutectic temperature and the freezing temperature is determined in dependence of the solid/liquid (s/l) interface shape and concentration. Where appropriate reference is made to the Jackson-Hunt analytical theory. It is shownmore » that there are mainly two typical conditions to decrease the undercooling: 1) a small liquidus slope and 2) the associated difference between the eutectic composition and the liquid composition during solidification.« less
The human milk oligosaccharides are not affected by pasteurization and freeze-drying.
Hahn, Won-Ho; Kim, Jaehan; Song, Seunghyun; Park, Suyeon; Kang, Nam Mi
2017-11-06
Human milk oligosaccharides (HMOs) are known as important factors in neurologic and immunologic development of neonates. Moreover, freeze-drying seems to be a promising storage method to improve the processes of human milk banks. However, the effects of pasteurization and freeze-drying on HMOs were not evaluated yet. The purpose of this study is to analyze and compare the HMOs profiles of human milk collected before and after the pasteurization and freeze-drying. Totally nine fresh human milk samples were collected from three healthy mothers at the first, second, and third week after delivery. The samples were treated with Holder pasteurization and freeze-drying. HMOs profiles were analyzed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight/time-of-flight (TOF/TOF) mass spectrometry and compared between samples collected before and after the treatments. Human milk samples showed significantly different HMO patterns between mothers. However, HMOs were not affected by lactation periods within 3 weeks after delivery (r 2 = 0.972-0.999, p < .001). Moreover, both of pasteurization and freeze-drying were found not to affect HMO patterns in a correlation analysis (r 2 = 0.989-0.999, p < .001). HMO patterns were found not to be affected by pasteurization and freeze-drying of donor milks. We hope that introducing freeze-drying to the human milk banks would be encouraged by the present study. However, the storage length without composition changes of HMOs after freeze-drying needs to be evaluated in the further studies.
Freeze substitution in 3 hours or less.
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. © 2011 The Authors Journal of Microscopy © 2011 Royal Microscopical Society.
Freeze-all policy: fresh vs. frozen-thawed embryo transfer.
Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo
2015-05-01
To compare in vitro fertilization (IVF) outcomes between fresh embryo transfer (ET) and frozen-thawed ET (the "freeze-all" policy), with fresh ET performed only in cases without progesterone (P) elevation. Prospective, observational, cohort study. Private IVF center. A total of 530 patients submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone-antagonist protocol, and cleavage-stage, day-3 ET. None. Ongoing pregnancy rates. A total of 530 cycles were included in the analysis: 351 in the fresh ET group (when P levels were ≤1.5 ng/mL on the trigger day); and 179 cycles in the freeze-all group (ET performed after endometrial priming with estradiol valerate, at 6 mg/d, taken orally). For the fresh ET group vs. the freeze-all group, respectively, the implantation rate was 19.9% and 26.5%; clinical pregnancy rate was 35.9% and 46.4%; and ongoing pregnancy rate was 31.1% and 39.7%. The IVF outcomes were significantly better in the group using the freeze-all policy, compared with the group using fresh ET. These results suggest that even in a select group of patients that underwent fresh ET (P levels ≤1.5 ng/mL), endometrial receptivity may have been impaired by COS, and outcomes may be improved by using the freeze-all policy. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.
Zheng, Guowei; Li, Lixia; Li, Weiqi
2016-03-22
Glycerolipids are the principal constituent of cellular membranes; remodelling of glycerolipids plays important roles in temperature adaptation in plants. Temperate plants can endure freezing stress, but even chilling at above-zero temperatures can induce death in tropical species. However, little is known about the differences in glycerolipid response to low temperatures between chilling-sensitive and freezing-tolerant plants. Using ESI-MS/MS-based lipidomic analysis, we compared the glycerolipidome of chilling (4 and 10 °C)-treated rice with that of freezing (-6 and -12 °C)-treated Arabidopsis, both immediately after these low-temperature treatments and after a subsequent recovery culture period. Arabidopsis is a 16:3 plant that harbours both eukaryotic and prokaryotic-type lipid synthesis pathways, while rice is an 18:3 plant that harbours only the eukaryotic lipid synthesis pathway. Arabidopsis contains higher levels of galactolipids than rice and has a higher double bond index (DBI). Arabidopsis contains lower levels of high melting point phosphatidylglycerol (PG) molecules and has a lower average acyl chain length (ACL). Marked phospholipid degradation occurred during the recovery culture period of non-lethal chilling treated rice, but did not occur in non-lethal freezing treated Arabidopsis. Glycerolipids with larger head groups were synthesized more in Arabidopsis than in rice at sub-lethal low-temperatures. Levels of phosphatidic acid (PA) and phosphatidylinositol (PI) rose in both plants after low-temperature treatment. The DBI and ACL of total lipids did not change during low-temperature treatment. A higher DBI and a lower ACL could make the membranes of Arabidopsis more fluid at low temperatures. The ability to synthesize glycerolipids containing a larger head group may correlate with low-temperature tolerance. The low-temperature-induced increase of PA may play a dual role in plant responses to low temperatures: as a lipid signal that initiates
Differential freezing resistance and photoprotection in C3 and C4 eudicots and grasses
Liu, Mei-Zhen; Osborne, Colin P.
2013-01-01
Globally, C4 plants dominate hot, open environments, but this general pattern is underpinned by important differences in the biogeography of C4 lineages. In particular, the species richness of C4 Poaceae (grasses) increases strongly with increasing temperature, whereas that of the major C4 eudicot group Chenopodiaceae correlates positively with aridity. Freezing tolerance is a crucial determinant of biogeographical relationships with temperature and is mediated by photodamage and cellular disruption by desiccation, but little is known about differences between C4 families. This study hypothesized that there is a greater risk of freezing damage via these mechanisms in C4 Poaceae than Chenopodiaceae, that freezing protection differs between the taxonomic groups, and that freezing tolerance of species is linked to arid habitat preference. Chlorophyll fluorescence, water relations, and freezing injury were compared in four C3 and six C4 species of Poaceae and Chenopodiaceae from the same Mongolian flora. Contrary to expectations, freezing-induced leaf mortality and photodamage were lower in Poaceae than Chenopodiaceae species, and unrelated to photosynthetic pathway. The freezing resistance of Poaceae species resulted from constitutive protection and cold acclimation and an ability to protect the photosynthetic apparatus from photodamage. Freezing protection was associated with low osmotic potential and low tissue elasticity, and freezing damage was accompanied by electrolyte leakage, consistent with cell-membrane disruption by ice. Both Chenopodiaceae and Poaceae had the potential to develop cold acclimation and withstand freezing during the growing season, which conflicted with the hypothesis. Instead, freezing tolerance was more closely associated with life history and ecological preference in these Mongolian species. PMID:23599273
Wheeler, M J; Mason, R H; Steunenberg, K; Wagstaff, M; Chou, C; Bertram, A K
2015-05-14
Ice nucleation on mineral dust particles is known to be an important process in the atmosphere. To accurately implement ice nucleation on mineral dust particles in atmospheric simulations, a suitable theory or scheme is desirable to describe laboratory freezing data in atmospheric models. In the following, we investigated ice nucleation by supermicron mineral dust particles [kaolinite and Arizona Test Dust (ATD)] in the immersion mode. The median freezing temperature for ATD was measured to be approximately -30 °C compared with approximately -36 °C for kaolinite. The freezing results were then used to test four different schemes previously used to describe ice nucleation in atmospheric models. In terms of ability to fit the data (quantified by calculating the reduced chi-squared values), the following order was found for ATD (from best to worst): active site, pdf-α, deterministic, single-α. For kaolinite, the following order was found (from best to worst): active site, deterministic, pdf-α, single-α. The variation in the predicted median freezing temperature per decade change in the cooling rate for each of the schemes was also compared with experimental results from other studies. The deterministic model predicts the median freezing temperature to be independent of cooling rate, while experimental results show a weak dependence on cooling rate. The single-α, pdf-α, and active site schemes all agree with the experimental results within roughly a factor of 2. On the basis of our results and previous results where different schemes were tested, the active site scheme is recommended for describing the freezing of ATD and kaolinite particles. We also used our ice nucleation results to determine the ice nucleation active site (INAS) density for the supermicron dust particles tested. Using the data, we show that the INAS densities of supermicron kaolinite and ATD particles studied here are smaller than the INAS densities of submicron kaolinite and ATD particles
Thermal Destabilization of Collagen Matrix Hierarchical Structure by Freeze/Thaw
Ozcelikkale, Altug; Han, Bumsoo
2016-01-01
This study aims to characterize and understand the effects of freezing on collagen structures and functionality. Specifically, thermodynamic destabilization of collagen at molecular- and fibril-levels by combination of low temperatures and freezing were experimentally characterized using modulated differential scanning calorimetry. In order to delineate the effects of sub-zero temperature and water-ice phase change, we hypothesized that the extent of destabilization can be determined based on post-thaw heat induced thermal denaturation of collagen. It is found that thermal denaturation temperature of collagen in hydrogel decreases by 1.4–1.6°C after freeze/thaw while no such decrease is observed in the case of molecular solution. The destabilization is predominantly due to ice formation. Exposure to low temperatures in the absence of ice has only minimal effect. Calorimetry measurements combined with morphological examination of collagen matrices by scanning electron microscopy suggest that freezing results in destabilization of collagen fibrils due to expansion of intrafibrillar space by ice formation. This fibril-level damage can be alleviated by use of cryoprotectant DMSO at concentrations as low as 0.5 M. A theoretical model explaining the change in collagen post-thaw thermal stability by freezing-induced fibril expansion is also proposed. PMID:26765741
The Adsorption and Desorption of Pb(2+) and Cd(2+) in Freeze-Thaw Treated Soils.
Li, Linhui; Ma, Jincai; Xu, Meng; Li, Xu; Tao, Jiahui; Wang, Guanzhu; Yu, Jitong; Guo, Ping
2016-01-01
Adsorption and desorption are important processes that influence the potential toxicity and bioavailability of heavy metals in soils. However, information regarding adsorption and desorption behavior of heavy metals in soils subjected to freeze-thaw cycles is poorly understood. In the current study, the effect of freeze-thaw cycles with different freezing temperature (-15, -25, -35°C) on soil properties was investigated. Then the adsorption and desorption behavior of Pb(2+) and Cd(2+) in freeze-thaw treated soils was studied. The adsorption amounts of Pb(2+) and Cd(2+) in freeze-thaw treated soils were smaller than those in unfrozen soils (p < 0.05), due to the fact that pH, cation exchange capacity, organic matter content, free iron oxide content, and CaCO3 content in freeze-thaw treated soils were smaller than those in unfrozen soils. The adsorption amounts of Pb(2+) and Cd(2+) in soils treated with lower freezing temperatures were higher than those in soils treated with higher freezing temperatures. Desorption percentages of Pb(2+) and Cd(2+) in unfrozen soils were smaller than those in freeze-thaw treated soils (p < 0.05). The desorption percentages of Pb(2+) and Cd(2+) were smaller in soils treated with lower freezing temperatures than those in soils treated with higher freezing temperatures. The results obtained highlight the change of the adsorption and desorption behavior of typical heavy metals in freeze-thaw treated soils located in seasonal frozen soils zone in northeast China.
Chaveiro, A; Machado, L; Frijters, A; Engel, B; Woelders, H
2006-06-01
The aim of this study was to improve the freezing protocol of bull sperm, by investigating the influence on sperm viability after freeze/thawing of different freezing medium components, as well as the effect of cooling rates in the different stages of the cooling protocol, in single factor experiments. The experimental variables were: (1) salt-based versus a sugar-based medium (Tris versus sucrose); (2) glycerol concentration; (3) detergent (Equex) concentration; (4) presence of bicarbonate; (5) rate of cooling from 22 degrees C to holding temperature (CR1); (6) holding temperature (HT); (7) rate of cooling from holding temperature to -6 degrees C (CR2); (8) rate of cooling from -10 to -100 degrees C (CR3). All experiments were performed using five bulls per experiment (three ejaculates per bull). Sperm motility after freezing and thawing was assessed by CASA system, and sperm membrane integrity was assessed by flow cytometry. Sucrose-based medium did not offer a clear significant benefit compared to Tris medium. The concentration of Equex that gave the best results in Tris-based media group and sucrose-based media group was in a range between 2-7 and 4-7 g/l, respectively. In both media groups, a glycerol concentration of 800 mM was the best in any post-thaw viability parameters. In the Tris media group, the presence of bicarbonate had a negative effect on sperm viability. CR1 and CR2 had no significant effect on any of the post-thaw sperm viability parameters, but a CR1=0.2 degrees C/min and CR2=4 degrees C/min appeared to give better results in both media. The holding temperature (HT) that gave the best results was found to be in the range of 5-9 degrees C. There was a significant disadvantage of using a low CR3 of 10 degrees C/min, while 150 degrees C/min appeared to be the best cooling rate for either medium.
Vernal freeze damage and genetic variation alter tree growth, chemistry, and insect interactions.
Rubert-Nason, Kennedy F; Couture, John J; Gryzmala, Elizabeth A; Townsend, Philip A; Lindroth, Richard L
2017-11-01
Anticipated consequences of climate change in temperate regions include early spring warmup punctuated by intermittent hard freezes. Warm weather accelerates leaf flush in perennial woody species, potentially exposing vulnerable young tissues to damaging frosts. We employed a 2 × 6 randomized factorial design to examine how the interplay of vernal (springtime) freeze damage and genetic variation in a hardwood species (Populus tremuloides) influences tree growth, phytochemistry, and interactions with an insect herbivore (Chaitophorus stevensis). Acute effects of freezing included defoliation and mortality. Surviving trees exhibited reduced growth and altered biomass distribution. Reflushed leaves on these trees had lower mass per area, lower lignin concentrations, and higher nitrogen concentrations, altered chemical defence profiles, and supported faster aphid population growth. Many effects varied among plant genotypes and were related with herbivore performance. This study suggests that a single damaging vernal freeze event can alter tree-insect interactions through effects on plant growth and chemistry. Differential responses of various genotypes to freeze damage suggest that more frequent vernal freeze events could also influence natural selection, favouring trees with greater freeze hardiness, and more resistance or tolerance to herbivores following damage. © 2017 John Wiley & Sons Ltd.
The interaction between freezing tolerance and phenology in temperate deciduous trees
Vitasse, Yann; Lenz, Armando; Körner, Christian
2014-01-01
Temperate climates are defined by distinct temperature seasonality with large and often unpredictable weather during any of the four seasons. To thrive in such climates, trees have to withstand a cold winter and the stochastic occurrence of freeze events during any time of the year. The physiological mechanisms trees adopt to escape, avoid, and tolerate freezing temperatures include a cold acclimation in autumn, a dormancy period during winter (leafless in deciduous trees), and the maintenance of a certain freezing tolerance during dehardening in early spring. The change from one phase to the next is mediated by complex interactions between temperature and photoperiod. This review aims at providing an overview of the interplay between phenology of leaves and species-specific freezing resistance. First, we address the long-term evolutionary responses that enabled temperate trees to tolerate certain low temperature extremes. We provide evidence that short term acclimation of freezing resistance plays a crucial role both in dormant and active buds, including re-acclimation to cold conditions following warm spells. This ability declines to almost zero during leaf emergence. Second, we show that the risk that native temperate trees encounter freeze injuries is low and is confined to spring and underline that this risk might be altered by climate warming depending on species-specific phenological responses to environmental cues. PMID:25346748
Freeze chromatography method and apparatus
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.
Santana, Héctor; García, Gerardo; Vega, Maribel; Beldarraín, Alejandro; Páez, Rolando
2015-01-01
We report on the stability assessment of a recombinant human epidermal growth factor (rhEGF) freeze-dried formulation for wound healing by intra-lesional injections. The suitability of packaging material for the light protection of finished dried powder was evaluated after stressed exposure conditions. Degradation kinetics of powder for injection was investigated at concentrations of 25-250 μg/vial and temperatures of 45, 60, and 70 °C. The long-term stability was evaluated after storage at 25 ± 2 °C/60 ± 5% relative humidity (6 months) and 2-8 °C (24 months) in the dark and analyzed at several time points. The stability after reconstitution with various diluents was also assessed after 24 h storage at 2-8 °C. The rhEGF samples were analyzed for structural integrity by reversed-phase high-performance liquid chromatography (RP-HPLC), size-exclusion HPLC, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Biological activity was investigated by measuring the cell proliferation in a murine fibroblast cell line. Results show that freeze-dried rhEGF in primary packaging only was photosensitive, as degradation by RP-HPLC that was completely suppressed by the secondary carton package was revealed. An increase in freeze-dried rhEGF stability was observed with the increase in protein concentration from 25 to 250 μg/vial. The long-term stability study showed no significant rhEGF degradation or physical change within the freeze-dried formulations containing 25 or 250 μg/vial of rhEGF. No physical, chemical or biological changes were observed for rhEGF after reconstitution in water for injection or 0.9% sodium chloride during the storage conditions studied. The stability of a recombinant human epidermal growth factor (rhEGF) freeze-dried formulation for wound healing by intra-lesional injections was assessed. The suitability of packaging material for the light protection of finished dried powder was evaluated after stressed exposure conditions
Freezing/Thawing without Cryoprotectant Damages Native but not Decellularized Porcine Renal Tissue
Poornejad, Nafiseh; Frost, Timothy S; Scott, Daniel R; Elton, Brinden B; Reynolds, Paul R; Roeder, Beverly L; Cook, Alonzo D
2015-01-01
abstract Whole organ decellularization of porcine renal tissue and recellularization with a patient's own cells would potentially overcome immunorejection, which is one of the most significant problems with allogeneic kidney transplantation. However, there are obstacles to achieving this goal, including preservation of the decellularized extracellular matrix (ECM), identifying the proper cell types, and repopulating the ECM before transplantation. Freezing biological tissue is the best option to avoid spoilage; however, it may damage the structure of the tissue or disrupt cellular membranes through ice crystal formation. Cryoprotectants have been used to repress ice formation during freezing, although cell toxicity can still occur. The effect of freezing/thawing on native (n = 10) and decellularized (n = 10) whole porcine kidneys was studied without using cryoprotectants. Results showed that the elastic modulus of native kidneys was reduced by a factor of 22 (P < 0.0001) by freezing/thawing or decellularization, while the elastic modulus for decellularized ECM was essentially unchanged by the freezing/thawing process (p = 0.0636). Arterial pressure, representative of structural integrity, was also reduced by a factor of 52 (P < 0.0001) after freezing/thawing for native kidneys, compared to a factor of 43 (P < 0.0001) for decellularization and a factor of 4 (P < 0.0001) for freezing/thawing decellularized structures. Both freezing/thawing and decellularization reduced stiffness, but the reductions were not additive. Investigation of the microstructure of frozen/thawed native and decellularized renal tissues showed increased porosity due to cell removal and ice crystal formation. Orcein and Sirius staining showed partial damage to elastic and collagen fibers after freezing/thawing. It was concluded that cellular damage and removal was more responsible for reducing stiffness than fibril destruction. Cell viability and growth were demonstrated on decellularized frozen
Raymond, Mélianie R; Wharton, David A
2013-02-01
The Antarctic nematode Panagrolaimus davidi is the best documented example of an animal surviving intracellular freezing and the only animal so far shown to survive such freezing throughout its tissues. However, a recent study found that after exposure to a freezing stress that produced intracellular freezing in a proportion of nematodes, the resulting survival levels could be explained if those nematodes that froze intracellularly had died. We have thus re-examined the survival of intracellular freezing in this nematode. The ability to survive a freezing exposure that is likely to produce intracellular freezing (freezing at -10 °C) declines with culture age. In cultures that are fed regularly, the ability to survive freezing at -10 °C increases, but in starved cultures freezing survival declines. Survival of intracellular freezing in fed cultures was confirmed using cryomicroscopy, staining of cells with vital dyes and by freeze substitution and transmission electron microscopy. We have thus confirmed that P. davidi can survive intracellular freezing and shown that this ability is dependent upon them being well fed. The effect of culture conditions on the nutrient status of the nematodes should thus be an important factor in the design of experiments.
Almeida, Osvaldo P; Flicker, Leon; Fenner, Stephen; Smith, Kate; Hyde, Zoe; Atkinson, David; Skeaf, Linda; Malay, Roslyn; LoGiudice, Dina
2014-01-01
This study aimed to develop a culturally acceptable and valid scale to assess depressive symptoms in older Indigenous Australians, to determine the prevalence of depressive disorders in the older Kimberley community, and to investigate the sociodemographic, lifestyle and clinical factors associated with depression in this population. Cross-sectional survey of adults aged 45 years or over from six remote Indigenous communities in the Kimberley and 30% of those living in Derby, Western Australia. The 11 linguistic and culturally sensitive items of the Kimberley Indigenous Cognitive Assessment of Depression (KICA-dep) scale were derived from the signs and symptoms required to establish the diagnosis of a depressive episode according to the DSM-IV-TR and ICD-10 criteria, and their frequency was rated on a 4-point scale ranging from 'never' to 'all the time' (range of scores: 0 to 33). The diagnosis of depressive disorder was established after a face-to-face assessment with a consultant psychiatrist. Other measures included sociodemographic and lifestyle factors, and clinical history. The study included 250 participants aged 46 to 89 years (mean±SD = 60.9±10.7), of whom 143 (57.2%) were women. The internal reliability of the KICA-dep was 0.88 and the cut-point 7/8 (non-case/case) was associated with 78% sensitivity and 82% specificity for the diagnosis of a depressive disorder. The point-prevalence of a depressive disorder in this population was 7.7%; 4.0% for men and 10.4% for women. Heart problems were associated with increased odds of depression (odds ratio = 3.3, 95% confidence interval = 1.2,8.8). The KICA-dep has robust psychometric properties and can be used with confidence as a screening tool for depression among older Indigenous Australians. Depressive disorders are common in this population, possibly because of increased stressors and health morbidities.
Pietsch, Kathrin; Allgaier, Antje-Kathrin; Frühe, Barbara; Rohde, Sabine; Hosie, Stuart; Heinrich, Martina; Schulte-Körne, Gerd
2011-09-01
Depression in adolescents is often hard to detect. In many cases paediatricians are the first point of contact. In order to increase recognition rates, screening instruments may be a helpful support for health care professionals. However, there is a lack of valid and economical screening instruments for primary care patients. Thus, the aim of the study was the development of the new Depression Screener for Teenagers (DesTeen) and its validation in a paediatric sample. 326 patients between 13 and 16 years old completed the DesTeen and a diagnostic interview, serving as gold standard. Prevalence rate for any depressive disorder (minor depression, major depression and dysthymia) was 12.6%. Psychometric properties were calculated. For validity measures, the area under the receiver operating characteristic curves (AUC) for any depressive disorder and the diagnostic subgroups was computed. DesTeen showed a high reliability (Cronbach's α=.87) and a high validity (AUC=.91). For the diagnostic subgroups AUC values did not significantly differ from overall accuracy of any depressive disorder (major depression: AUC=.95, p=.179; dysthymia: AUC=.88, p=.605; minor depression: AUC=.87, p=.327). The optimal cut-off point for any depressive disorder according to the Youden-Index yielded a sensitivity of .90 and a specificity of .80. An abbreviated 5-item version of DesTeen showed no loss in validity (AUC=.90, p=.695). Overall, DesTeen can be regarded as a valid screening instrument for adolescent paediatric patients. For practical use, the 5-item version is even more promising. A replication of these results is essential. Copyright © 2011 Elsevier B.V. All rights reserved.
Santiago-Moreno, J; Esteso, M C; Pradiee, J; Castaño, C; Toledano-Díaz, A; O'Brien, E; Lopez-Sebastián, A; Martínez-Nevado, E; Delclaux, M; Fernández-Morán, J; Zhihe, Z
2016-05-01
This work examines the effects of subsequent cycles of freezing-thawing on giant panda (Ailuropoda melanoleuca) sperm morphometry and function, and assesses whether density-gradient centrifugation (DGC) can increase the number of freezing-thawing cycles this sperm can withstand. A sperm sample was collected by electroejaculation from a mature giant panda and subjected to five freezing-thawing cycles. Although repeated freezing-thawing negatively affected (P < 0.05) sperm motility and membrane integrity, in both nonselected and DCG-selected sperm samples, >60% of the sperm cells in both treatments showed acrosome integrity even after the fifth freezing cycle. In fresh semen, the sperm head length was 4.7 μm, the head width 3.6 μm, area 14.3 μm(2) and perimeter length 14.1 μm. The present results suggest that giant panda sperm trends to be resistant to repeated freezing-thawing, even without DGC selection. © 2015 Blackwell Verlag GmbH.
Role of ice structuring proteins on freezing-thawing cycles of pasta sauces.
Calderara, Marianna; Deorsola, Fabio A; Bensaid, Samir; Fino, Debora; Russo, Nunzio; Geobaldo, Francesco
2016-12-01
The freezing of the food is one of the most important technological developments for the storage of food in terms of quality and safety. The aim of this work was to study the role of an ice structuring protein (ISP) on freezing-thawing cycles of different solutions and commercial Italian pasta sauces. Ice structuring proteins were related to the modification of the structure of ice. The results showed that the freezing time of an aqueous solution containing the protein was reduced to about 20% with respect to a pure water solution. The same effect was demonstrated in sugar-containing solutions and in lipid-containing sauces. The study proved a specific role of ISP during thawing, inducing a time decrease similar to that of freezing and even more important in the case of tomato-based sauces. This work demonstrated the role of ISP in the freezing-thawing process, showing a significant reduction of processing in the freezing and thawing phase by adding the protein to pure water and different sugar-, salt- and lipid-containing solutions and commercial sauces, with considerable benefits for the food industry in terms of costs and food quality.
Limited Impact of Subglacial Supercooling Freeze-on for Greenland Ice Sheet Stratigraphy
NASA Astrophysics Data System (ADS)
Dow, Christine F.; Karlsson, Nanna B.; Werder, Mauro A.
2018-02-01
Large units of disrupted radiostratigraphy (UDR) are visible in many radio-echo sounding data sets from the Greenland Ice Sheet. This study investigates whether supercooling freeze-on rates at the bed can cause the observed UDR. We use a subglacial hydrology model to calculate both freezing and melting rates at the base of the ice sheet in a distributed sheet and within basal channels. We find that while supercooling freeze-on is a phenomenon that occurs in many areas of the ice sheet, there is no discernible correlation with the occurrence of UDR. The supercooling freeze-on rates are so low that it would require tens of thousands of years with minimal downstream ice motion to form the hundreds of meters of disrupted radiostratigraphy. Overall, the melt rates at the base of the ice sheet greatly overwhelm the freeze-on rates, which has implications for mass balance calculations of Greenland ice.
Expanding reproductive lifespan: a cost-effectiveness study on oocyte freezing.
van Loendersloot, L L; Moolenaar, L M; Mol, B W J; Repping, S; van der Veen, F; Goddijn, M
2011-11-01
The average age of women bearing their first child has increased strongly. This is an important reproductive health problem as fertility declines with increasing female age. Unfortunately, IVF using fresh oocytes cannot compensate for this age-related fertility decline. Oocyte freezing could be a solution. We used the Markov model to estimate the cost-effectiveness of three strategies for 35-year-old women who want to postpone pregnancy till the age of 40: Strategy 1: women undergo three cycles of ovarian hyperstimulation at age 35 for oocyte freezing, then at age 40, use these frozen oocytes for IVF; Strategy 2: women at age 40 attempt to conceive without treatment; and the reference strategy: women at age 40 attempt to conceive and, if not pregnant after 1 year, undergo IVF. Sensitivity analyses were carried out to investigate assumptions of the model and to identify which model inputs had most impact on the results. Oocyte freezing (Strategy 1) resulted in a live birth rate of 84.5% at an average cost of €10,419. Natural conception (Strategy 2) resulted in a live birth rate of 52.3% at an average cost of €310 per birth. IVF (the reference strategy) resulted in a cumulative live birth rate of 64.6% at an average cost of €7798. The cost per additional live birth for the oocyte freezing strategy was €13,156 compared to the IVF strategy. If at least 61% of the women return to collect their oocytes, and if there is a willingness to pay €19,560 extra per additional live birth, the oocyte freezing strategy is the most cost-effective strategy. Oocyte freezing is more cost effective compared to IVF, if at least 61% of the women return to collect their oocytes and if one is willing to pay €19,560 extra per additional live birth. Our Markov model shows that, considering all the used assumptions, oocyte freezing provides more value for money than IVF.
Post-adoption Depression: Parental Classes of Depressive Symptoms Across Time
Foli, Karen J.; South, Susan C.; Lim, Eunjung; Jarnecke, Amber
2016-01-01
Background Approximately 10%-15% of birth mothers and fathers experience postpartum depression, but reports of depressive symptoms in adoptive parents are more variable. Findings from investigators range from 10%-32%, which may mask the experiences of distinct groups of adoptive parents from pre-to post-placement of a child. Methods We performed latent class growth analysis using the Center for Epidemiologic Studies-Depression scores of 129 primarily heterosexual, adoptive parents (50% females) for three time points: 4-6 weeks pre-placement of the child, 4-6 weeks post-placement, and 5-6 months post-placement. Mixed effects models by parent depressive trajectories were also conducted for three types of variables: interpersonal, psychological symptoms, and life orientation. Results Five classes of depressive symptom trajectories were found. The majority of parents (71%) belonged to a class with low levels of depressive symptoms across time. However, two classes of parents were above the threshold for depressive symptoms at placement, and three classes of parents were above the threshold at 6 months post-placement. The majority of interpersonal, psychological symptom, and life orientation variables were significant across classes and by time. Limitations The homogeneity of the sample calls for replication of study findings. Conclusions An explanation for inconsistencies in the range of adoptive parent depressive symptoms may be explained by different subgroups of parents who vary by their trajectory of depressive symptoms before and after placement of the child. Adoption and mental health professionals should be aware that select adoptive parents may struggle pre-and post-placement of a child. PMID:27155072
Post-adoption depression: Parental classes of depressive symptoms across time.
Foli, Karen J; South, Susan C; Lim, Eunjung; Jarnecke, Amber M
2016-08-01
Approximately 10-15% of birth mothers and fathers experience postpartum depression, but reports of depressive symptoms in adoptive parents are more variable. Findings from investigators range from 10% to 32%, which may mask the experiences of distinct groups of adoptive parents from pre-to post-placement of a child. We performed latent class growth analysis using the Center for Epidemiologic Studies-Depression scores of 129 primarily heterosexual, adoptive parents (50% females) for three time points: 4-6 weeks pre-placement of the child, 4-6 weeks post-placement, and 5-6 months post-placement. Mixed effects models by parent depressive trajectories were also conducted for three types of variables: interpersonal, psychological symptoms, and life orientation. Five classes of depressive symptom trajectories were found. The majority of parents (71%) belonged to a class with low levels of depressive symptoms across time. However, two classes of parents were above the threshold for depressive symptoms at placement, and three classes of parents were above the threshold at 6 months post-placement. The majority of interpersonal, psychological symptom, and life orientation variables were significant across classes and by time. The homogeneity of the sample calls for replication of study findings. An explanation for inconsistencies in the range of adoptive parent depressive symptoms may be explained by different subgroups of parents who vary by their trajectory of depressive symptoms before and after placement of the child. Adoption and mental health professionals should be aware that select adoptive parents may struggle pre-and post-placement of a child. Copyright © 2016 Elsevier B.V. All rights reserved.
Freeze-all cycle in reproductive medicine: current perspectives.
Roque, Matheus; Valle, Marcello; Kostolias, Alessandra; Sampaio, Marcos; Geber, Selmo
2017-02-01
The freeze-all strategy has emerged as an alternative to fresh embryo transfer (ET) during in vitro fertilization (IVF) cycles. Although fresh ET is the norm during assisted reproductive therapies (ART), there are many concerns about the possible adverse effects of controlled ovarian stimulation (COS) over the endometrium. The supra-physiologic hormonal levels that occur during a conventional COS are associated with modifications in the peri-implantation endometrium, which may be related to a decrease in pregnancy rates and poorer obstetric and perinatal outcomes when comparing fresh to frozen-thawed embryo transfers. The main objective of this study was to assess the available literature regarding the freeze-all strategy in IVF cycles, in regards to effectiveness and safety. Although there are many potential advantages in performing a freeze-all cycle over a fresh ET, it seems that the freeze-all strategy is not designed for all IVF patients. There is a need to develop a non-invasive clinical tool to evaluate the endometrial receptivity during a fresh cycle, which enables the selection of patients that would benefit from this strategy. Today, it is reasonable to perform elective cryopreservation of all oocytes/embryos in cases with a risk of OHSS development, and in patients with supra-physiologic hormonal levels during the follicular phase of COS. It is not clear if all normal responders and poor responders may benefit from this strategy.
A whole-plant screening test to identify genotypes with superior freezing tolerance.
Bertrand, Annick; Castonguay, Yves; Bourassa, Josée
2014-01-01
Freezing tolerance is a determinant factor of persistence of perennials grown in northern climate. Selection for winterhardiness in field nurseries is difficult because of the unpredictability of occurrence of test winters allowing the identification of hardy genotypes. Here we describe a whole-plant assay entirely performed indoor in growth chambers and walk-in freezers to identify genotypes with superior tolerance to freezing within populations of open pollinated species. Three successive freezing stresses are applied to progressively eliminate 90 % of the population and to retain only the 10 % best performing genotypes. This approach can be used to generate recurrently selected populations more tolerant to freezing in different species.
Sperm Preservation by Freeze-Drying for the Conservation of Wild Animals
Kaneko, Takehito; Ito, Hideyuki; Sakamoto, Hidefusa; Onuma, Manabu; Inoue-Murayama, Miho
2014-01-01
Sperm preservation is a useful technique for the maintenance of biological resources in experimental and domestic animals, and in wild animals. A new preservation method has been developed that enables sperm to be stored for a long time in a refrigerator at 4°C. Sperm are freeze-dried in a solution containing 10 mM Tris and 1 mM EDTA. Using this method, liquid nitrogen is not required for the storage and transportation of sperm. We demonstrate that chimpanzee, giraffe, jaguar, weasel and the long-haired rat sperm remain viable after freeze-drying. In all species, pronuclei were formed after the injection of freeze-dried sperm into the mouse oocytes. Although preliminary, these results may be useful for the future establishment of “freeze-drying zoo” to conserve wild animals. PMID:25409172
Sperm preservation by freeze-drying for the conservation of wild animals.
Kaneko, Takehito; Ito, Hideyuki; Sakamoto, Hidefusa; Onuma, Manabu; Inoue-Murayama, Miho
2014-01-01
Sperm preservation is a useful technique for the maintenance of biological resources in experimental and domestic animals, and in wild animals. A new preservation method has been developed that enables sperm to be stored for a long time in a refrigerator at 4 °C. Sperm are freeze-dried in a solution containing 10 mM Tris and 1 mM EDTA. Using this method, liquid nitrogen is not required for the storage and transportation of sperm. We demonstrate that chimpanzee, giraffe, jaguar, weasel and the long-haired rat sperm remain viable after freeze-drying. In all species, pronuclei were formed after the injection of freeze-dried sperm into the mouse oocytes. Although preliminary, these results may be useful for the future establishment of "freeze-drying zoo" to conserve wild animals.
Impact of freezing and thawing on the quality of meat: review.
Leygonie, Coleen; Britz, Trevor J; Hoffman, Louwrens C
2012-06-01
This comprehensive review describes the effects of freezing and thawing on the physical quality parameters of meat. The formation of ice crystals during freezing damages the ultrastructure and concentrates the solutes in the meat which, in turn, leads to alterations in the biochemical reactions that occur at the cellular level and influence the physical quality parameters of the meat. The quality parameters that were evaluated are moisture loss, protein denaturation, lipid and protein oxidation, colour, pH, shear force and microbial spoilage. Additionally mechanisms employed to mitigate the effects of freezing and thawing were also reviewed. These include the use of novel methods of freezing and thawing, ante and post mortem antifreeze protein inclusion and vitamin E supplementation, brine injection and modified atmospheric packaging. Copyright © 2012 Elsevier Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Bogorodsky, Petr; Marchenko, Aleksey; Pnyushkov, Andrey; Filchuk, Kirill; Morozov, Yevgenii; Ryzhov, Ivan
2017-04-01
The results of oceanographic and sea ice studies in the shallow Braganzavågen Gulf (Van Mijenfjorden, Svalbard) in March 2016 are presented. These studies are a continuation of observational efforts initiated by UNIS (Svalbard, Norway) in 2014. 2016 field campaign includes instrumental measurements of snow and ice properties in the fjord (e.g., ice thicknesses, temperatures, and salinities), as well as high-resolution CTD measurements within the under-ice water column. Collected observations were accompanied by freezing simulations of adjacent water and bottom ground layers performed with a one-dimensional thermodynamic model (Bogorodskii and Pnyushkov, 2015). The model uses two methods to reproduce phase transition areas - a "classic" (frontal) method for the fast ice, and transition in the continuous media (mushy zone) for the bottom sediments. Meteorological observations during the winter 2015-16 at Sveagruva (northwest coast) were used in these simulations as the atmospheric forcing. Numerical experiments were carried out for the initial salinity of 35 psu and 2 m water depth. The simulations start with the beginning of water freezing determined by a steady air temperature transition through the freezing point. The start of freezing was also verified by comparison with sea ice charts available for the Van Mijenfjorden for the period of simulations. Model simulations showed that the growth of sea ice in shallow (<1 m) areas of the basin significantly increases water salinity in the under-ice layer. For instance, at a 0.5 m depth the salinity in the under ice water layer exceeds 160 psu, which corresponds to the freezing temperature below -9C. In fact, the water salinity does not reach high values because of the horizontal mixing. However, available hydrological observations showed relatively small (0.2-0.5 m) amplitudes of tides - the major contributor to the horizontal exchange in this area. These small amplitudes likely suggest small advective salt fluxes
9 CFR 381.66 - Temperatures and chilling and freezing procedures.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Temperatures and chilling and freezing procedures. 381.66 Section 381.66 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT... Procedures § 381.66 Temperatures and chilling and freezing procedures. (a) General. Temperatures and...
Matijasevich, Alicia; Munhoz, Tiago N; Tavares, Beatriz Franck; Barbosa, Ana Paula Pereira Neto; da Silva, Diego Mello; Abitante, Morgana Sonza; Dall'Agnol, Tatiane Abreu; Santos, Iná S
2014-10-08
Standardized questionnaires designed for the identification of depression are useful for monitoring individual as well as population mental health. The Edinburgh Postnatal Depression Scale (EPDS) has originally been developed to assist primary care health professionals to detect postnatal depression, but several authors recommend its use outside of the postpartum period. In Brazil, the use of the EPDS for screening depression outside the postpartum period and among non-selected populations has not been validated. The present study aimed to assess the validity of the EPDS as a screening instrument for major depressive episode (MDE) among adults from the general population. This is a validation study that used a population-based sampling technique to select the participants. The study was conducted in the city of Pelotas, Brazil. Households were randomly selected by two stage conglomerates with probability proportional to size. EPDS was administered to 447 adults (≥20 years). Approximately 17 days later, participants were reinterviewed by psychiatrics and psychologists using a structured diagnostic interview (Mini International Neuropsychiatric Interview, MINI). We calculated the sensitivity and specificity of each cutoff point of EPDS, and values were plotted as a receiver operator characteristic curve. The best cutoff point for screening depression was ≥8, with 80.0% (64.4 - 90.9%) sensitivity and 87.0% (83.3 - 90.1%) specificity. Among women the best cutoff point was ≥8 too with values of sensitivity and specificity of 84.4% (67.2 - 94.7%) and 81.3% (75.5 - 86.1%), respectively. Among men, the best cutoff point was ≥7 (75% sensitivity and 89% specificity). The EPDS was shown to be suitable for screening MDE among adults in the community.
[Severe depression : psychoanalysis].
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. Copyright 2009 L'Encéphale. Published by Elsevier Masson SAS.. All rights reserved.
Ice-binding proteins confer freezing tolerance in transgenic Arabidopsis thaliana.
Bredow, Melissa; Vanderbeld, Barbara; Walker, Virginia K
2017-01-01
Lolium perenne is a freeze-tolerant perennial ryegrass capable of withstanding temperatures below -13 °C. Ice-binding proteins (IBPs) presumably help prevent damage associated with freezing by restricting the growth of ice crystals in the apoplast. We have investigated the expression, localization and in planta freezing protection capabilities of two L. perenne IBP isoforms, LpIRI2 and LpIRI3, as well as a processed IBP (LpAFP). One of these isoforms, LpIRI2, lacks a conventional signal peptide and was assumed to be a pseudogene. Nevertheless, both LpIRI2 and LpIRI3 transcripts were up-regulated following cold acclimation. LpIRI2 also demonstrated ice-binding activity when produced recombinantly in Escherichia coli. Both the LpIRI3 and LpIRI2 isoforms appeared to accumulate in the apoplast of transgenic Arabidopsis thaliana plants. In contrast, the fully processed isoform, LpAFP, remained intracellular. Transgenic plants expressing either LpIRI2 or LpIRI3 showed reduced ion leakage (12%-39%) after low-temperature treatments, and significantly improved freezing survival, while transgenic LpAFP-expressing lines did not confer substantial subzero protection. Freeze protection was further enhanced by with the introduction of more than one IBP isoform; ion leakage was reduced 26%-35% and 10% of plants survived temperatures as low as -8 °C. Our results demonstrate that apoplastic expression of multiple L. perenne IBP isoforms shows promise for providing protection to crops susceptible to freeze-induced damage. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.
Ice nucleating agents allow embryo freezing without manual seeding.
Teixeira, Magda; Buff, Samuel; Desnos, Hugo; Loiseau, Céline; Bruyère, Pierre; Joly, Thierry; Commin, Loris
2017-12-01
Embryo slow freezing protocols include a nucleation induction step called manual seeding. This step is time consuming, manipulator dependent and hard to standardize. It requires access to samples, which is not always possible within the configuration of systems, such as differential scanning calorimeters or cryomicroscopes. Ice nucleation can be induced by other methods, e.g., by the use of ice nucleating agents. Snomax is a commercial preparation of inactivated proteins extracted from Pseudomonas syringae. The aim of our study was to investigate if Snomax can be an alternative to manual seeding in the slow freezing of mouse embryos. The influence of Snomax on the pH and osmolality of the freezing medium was evaluated. In vitro development (blastocyst formation and hatching rates) of fresh embryos exposed to Snomax and embryo cryopreserved with and without Snomax was assessed. The mitochondrial activity of frozen-thawed blastocysts was assessed by JC-1 fluorescent staining. Snomax didn't alter the physicochemical properties of the freezing medium, and did not affect embryo development of fresh embryos. After cryopreservation, the substitution of manual seeding by the ice nucleating agent (INA) Snomax did not affect embryo development or embryo mitochondrial activity. In conclusion, Snomax seems to be an effective ice nucleating agent for the slow freezing of mouse embryos. Snomax can also be a valuable alternative to manual seeding in research protocols in which manual seeding cannot be performed (i.e., differential scanning calorimetry and cryomicroscopy). Copyright © 2017 Elsevier Inc. All rights reserved.
Inferential Style, School Teachers, and Depressive Symptoms in College Students
ERIC Educational Resources Information Center
Pittard, Caroline M.; Pössel, Patrick; Lau, Timothy
2017-01-01
Depressive symptoms affect around half of students at some point during college. According to the hopelessness theory of depression, making negative inferences about stressful events is a vulnerability for developing depression. Negative and socio-emotional teaching behavior can be stressors that are associated with depression in school students.…
FY 2017 Status of Sodium Freezing and Remelting Tests
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lv, Q.; Boron, E.; Momozaki, Y.
The Sodium Freezing and Remelting experiment facility at Argonne National Laboratory has been significantly modified and improved. The main improvement was replacement of the two original stainless steel test sections that had strain gages limited by their bonds to the stainless steel to maximum temperatures of 350°C with a single new test section with strain gages that can be utilized up to 980°C and a thin wall to enhance measured strains. Wetting of stainless steel by sodium within a practical time of one to a few days is expected to require temperatures of 450°C or greater. Thus, the higher temperaturemore » strain gages enable wetting in a short time of a few days. Wetting below 350°C would have required an impractically long time of at least weeks. Other improvements included upgrading of the loop configuration, incorporation of a cold finger to purify sodium, a new data acquisition system, and reinstallation of the many heaters, heater controllers, and thermocouples. After the loop had been heated to 400°C for about two hours, an initial sodium freezing test was conducted. It is thought that the sodium might have at least partially wetted the stainless steel wall under these conditions. The strain gage measurements indicate that an incremental step inward deformation of the test section thin wall occurred as the temperature decreased through the sodium freezing temperature. This behavior is consistent with sodium initially adhering to the stainless steel inner wall but breaking away from the wall as the freezing sodium contracted. Conduct of additional sodium freezing tests under well wetted conditions was prevented as a result of stoppage of all electrical work at Argonne by the Laboratory Director on July 25, 2017. A pathway to resuming electrical work is now in place at Argonne and additional sodium freezing testing will resume next fiscal year.« less
Hatchling painted turtles (Chrysemys picta) survive only brief freezing of their bodily fluids.
Attaway, M B; Packard, G C; Packard, M J
1998-07-01
Neonatal painted turtles (Chrysemys picta) spend their first winter inside the shallow, subterranean nest cavity where they completed embryogenesis. Consequently, hatchlings at high latitudes may be exposed to ice and cold during the winter. This study was undertaken to determine how long hatchlings withstand freezing at temperatures slightly below 0 degree C because tolerance for freezing has been proposed to be the key to survival by overwintering animals. A thermocouple was glued to the carapace of each hatchling. The animal was dipped in water to provide a site of nucleation of ice and was then placed into a glass jar that was partially immersed in a circulating bath at -2 degrees C. Carapace temperature was monitored throughout the procedure. When a freezing exotherm was detected, timing of the freezing event began. Animals were maintained in a frozen state for 12-48 h prior to being warmed to room temperature. Of the 39 hatchlings, 22 did not survive, and mortality increased as the duration of freezing increased. Logistic regression indicates that no turtle would have survived in a frozen state for more than 54 h. These results indicate that hatchlings can survive only brief exposure to freezing of the body fluids. Thus, hatchlings cannot tolerate freezing during prolonged periods of cold.
Effect of freeze-thaw cycles on greenhouse gas fluxes from peat soils
NASA Astrophysics Data System (ADS)
Oh, H. D.; Rezanezhad, F.; Markelov, I.; McCarter, C. P. R.; Van Cappellen, P.
2017-12-01
The ongoing displacement of climate zones by global warming is increasing the frequency and intensity of freeze-thaw cycles in middle and high latitude regions, many of which are dominated by organic soils such as peat. Repeated freezing and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical cycling of carbon and nutrients. In this presentation, we focus on how freeze-thaw cycles influence greenhouse gas fluxes from peat using a newly developed experimental soil column system that simulates realistic soil temperature profiles during freeze-thaw cycles. We measured the surface and subsurface changes to gas and aqueous phase chemistry to delineate the diffusion pathways and quantify soil greenhouse gas fluxes during freeze-thaw cycles using sulfur hexafluoride (SF6) as a conservative tracer. Three peat columns were assembled inside a temperature controlled chamber with different soil structures. All three columns were packed with 40 cm of undisturbed, slightly decomposed peat, where the soil of two columns had an additional 10 cm layer on top (one with loose Sphagnum moss and one with an impermeable plug). The results indicate that the release of SF6 and CO2 gas from the soil surface was influenced by the recurrent development of a physical ice barrier, which prevented gas exchange between the soil and atmosphere during freezing conditions. With the onset of thawing a pulse of SF6 and CO2 occurred, resulting in a flux of 3.24 and 2095.52 µmol/m2h, respectively, due to the build-up of gases in the liquid-phase pore space during freezing. Additionally, we developed a model to determine the specific diffusion coefficients for each peat column. These data allow us to better predict how increased frequency and intensity of freeze-thaw cycles will affect greenhouse gas emissions in northern peat soils.
Freezing and drying effects on potential plant contributions to phosphorus in runoff.
Roberson, Tiffany; Bundy, Larry G; Andraski, Todd W
2007-01-01
Phosphorus (P) in runoff from landscapes can promote eutrophication of natural waters. Soluble P released from plant material can contribute significant amounts of P to runoff particularly after plant freezing or drying. This study was conducted to evaluate P losses from alfalfa or grass after freezing or drying as potential contributors to runoff P. Alfalfa (Medicago sativa L.) and grass (principally, Agropyron repens L.) plant samples were subjected to freezing and drying treatments to determine P release. Simulated rainfall runoff and natural runoff from established alfalfa fields and a grass waterway were collected to study P contributions from plant tissue to runoff. The effects of freezing and drying on P released from plant tissue were simulated by a herbicide treatment in selected experiments. Soluble reactive P (SP) extracted from alfalfa and grass samples was markedly increased by freezing or drying. In general, SP extracted from plant samples increased in the order fresh < frozen < frozen/thawed < dried, and averaged 1, 8, 14, and 26% of total P in alfalfa, respectively. Soluble reactive P extracted from alfalfa after freezing or drying increased with increasing soil test P (r(2) = 0.64 to 0.68), suggesting that excessive soil P levels increased the risk of plant P contributions to runoff losses. In simulated rainfall studies, paraquat (1,1'-dimethyl-4, 4''-bipyridinium ion) treatment of alfalfa increased P losses in runoff, and results suggested that this treatment simulated the effects of drying on plant P loss. In contrast to the simulated rainfall results, natural runoff studies over 2 yr did not show higher runoff P losses that could be attributed to P from alfalfa. Actual P losses likely depend on the timing and extent of plant freezing and drying and of precipitation events after freezing.
Immersion and contact freezing experiments in the Mainz wind tunnel laboratory
NASA Astrophysics Data System (ADS)
Eppers, Oliver; Mayer, Amelie; Diehl, Karoline; Mitra, Subir; Borrmann, Stephan; Szakáll, Miklós
2016-04-01
Immersion and contact freezing are of outmost important ice nucleation processes in mixed phase clouds. Experimental studies are carried out in the Mainz vertical wind tunnel laboratory in order to characterize these nucleation processes for different ice nucleating particles (INP), such as for mineral dust or biological particles. Immersion freezing is investigated in our laboratory with two different experimental techniques, both attaining contact-free levitation of liquid droplets and cooling of the surrounding air down to about -25 °C. In an acoustic levitator placed in the cold room of our laboratory, drops with diameters of 2 mm are investigated. In the vertical air stream of the wind tunnel droplets with diameter of 700 micron are freely floated at their terminal velocities, simulating the flow conditions of the free atmosphere. Furthermore, the wind tunnel offers a unique platform for contact freezing experiments. Supercooled water droplets are floated in the vertical air stream at their terminal velocities and INP are injected into the tunnel air stream upstream of them. As soon as INP collides with the supercooled droplet the contact freezing is initiated. The first results of immersion and contact freezing experiments with cellulose particles both in the acoustic levitator and in the wind tunnel will be presented. Cellulose is considered as typical INP of biological origin and a macrotracer for plant debris. Nucleating properties of cellulose will be provided, mainly focusing on the temperature, INP concentration, and specific surface area dependences of the freezing processes. Direct comparison between the different experimental techniques (acoustic levitator and wind tunnel), as well as between nucleation modes (immersion and contact freezing) will be presented. The work is carried out within the framework of the German research unit INUIT.
Improved cryopreservability of stallion sperm using a sorbitol-based freezing extender.
Pojprasath, T; Lohachit, C; Techakumphu, M; Stout, T; Tharasanit, T
2011-06-01
Cryopreservation of stallion semen is often associated with poor post-thaw sperm quality. Sugars are among the important components of a freezing extender and act as non-permeating cryoprotectants. This study aimed to compare the quality of stallion sperm frozen with glucose, fructose or sorbitol-containing freezing extenders. Semen was collected from six stallions of proven fertility and cryopreserved using a freezing extender containing different types of monosaccharide sugars (glucose, fructose or sorbitol). After thawing, the semen was examined for sperm motility, viability, acrosome integrity, plasma membrane functionality and sperm longevity. The fertility of semen frozen in the presence of sorbitol was also tested by artificial insemination. Sperm quality was significantly decreased following freezing and thawing (P < 0.05). Fructose was inferior for protecting sperm during cryopreservation when compared to sorbitol and glucose (P < 0.05). Although the viability, motility and acrosome integrity of sperm cryopreserved with a glucose-containing extender did not significantly differ from sperm frozen in the sorbitol-based extender when examined at 2 and 4 h post-thaw, all of these parameters plus plasma membrane functionality were improved for sperm frozen in the sorbitol extender than in the glucose extender when examined 10 min post-thaw. Two of four mares (50%) inseminated with semen frozen with a sorbitol-containing freezing extender became pregnant. It is concluded that different sugars have different abilities to protect against cryoinjury during freezing and thawing of stallion sperm. This study demonstrated that an extender containing sorbitol as primary sugar can be used to successfully cryopreserve equine sperm; moreover, the quality of frozen-thawed sperm appeared to be better than when glucose or fructose was the principle sugar in the freezing extender. Copyright © 2011 Elsevier Inc. All rights reserved.
Running out of time: exploring women's motivations for social egg freezing.
Baldwin, Kylie; Culley, Lorraine; Hudson, Nicky; Mitchell, Helene
2018-04-12
Few qualitative studies have explored women's use of social egg freezing. Derived from an interview study of 31 participants, this article explores the motivations of women using this technology. Semi-structured interviews were conducted with 31 users of social egg freezing resident in UK (n = 23), USA (n = 7) and Norway (n = 1). Interviews were face to face (n = 16), through Skype and Facetime (n = 9) or by telephone (n = 6). Data were analyzed using interpretive thematic analysis. Women's use of egg freezing was shaped by fears of running out of time to form a conventional family, difficulties in finding a partner and concerns about "panic partnering", together with a desire to avoid future regrets and blame. For some women, use of egg freezing was influenced by recent fertility or health diagnoses as well as critical life events. A fifth of the participants also disclosed an underlying fertility or health issue as affecting their decision. The study provides new insights in to the complex motivations women have for banking eggs. It identifies how women's use of egg freezing was an attempt to "preserve fertility" in the absence of the particular set of "life conditions" they regarded as crucial for pursuing parenthood. It also demonstrates that few women were motivated by a desire to enhance their career and that the boundaries between egg freezing for medical and for social reasons may be more porous than first anticipated.
Unprecedented Cell-Selection Using Ultra-Quick Freezing Combined with Aquaporin Expression
Kato, Yasuhiro; Miyauchi, Takayuki; Abe, Youichiro; Kojić, Dušan; Tanaka, Manami; Chikazawa, Nana; Nakatake, Yuhki; Ko, Shigeru B. H.; Kobayashi, Daisuke; Hazama, Akihiro; Fujiwara, Shoko; Uchida, Tatsuya; Yasui, Masato
2014-01-01
Freezing is usually used for preservation and storage of biological samples; however, this process may have some adverse effects such as cell membrane damage. Aquaporin (AQP), a water channel protein, has been suggested to play some roles for cryopreservation although its molecular mechanism remains unclear. Here we show that membrane damage caused by ultra-quick freezing is rescued by the expression of AQP4. We next examine if the expression of AQP combined with ultra-quick freezing can be used to select cells efficiently under freezing conditions where most cells are died. CHO cells stably expressing AQP4 were exclusively selected from mixed cell cultures. Having identified the increased expression of AQP4 during ES cell differentiation into neuro-ectoderm using bioinformatics, we confirmed the improved survival of differentiated ES cells with AQP4 expression. Finally we show that CHO cells transiently transfected with Endothelin receptor A and Aqp4 were also selected and concentrated by multiple cycles of freezing/thawing, which was confirmed with calcium imaging in response to endothelin. Furthermore, we found that the expression of AQP enables a reduction in the amount of cryoprotectants for freezing, thereby decreasing osmotic stress and cellular toxicity. Taken together, we propose that this simple but efficient and safe method may be applicable to the selection of mammalian cells for applications in regenerative medicine as well as cell-based functional assays or drug screening protocols. PMID:24558371
Lesions causing freezing of gait localize to a cerebellar functional network
Fasano, Alfonso; Laganiere, Simon E.; Lam, Susy; Fox, Michael D.
2016-01-01
Objective Freezing of gait is a disabling symptom in Parkinson’s disease and related disorders, but the brain regions involved in symptom generation remain unclear. Here we analyze brain lesions causing acute onset freezing of gait to identify regions causally involved in symptom generation. Methods Fourteen cases of lesion-induced freezing of gait were identified from the literature and lesions were mapped to a common brain atlas. Because lesion-induced symptoms can come from sites connected to the lesion location, not just the lesion location itself, we also identified brain regions functionally connected to each lesion location. This technique, termed lesion network mapping, has been recently shown to identify regions involved in symptom generation across a variety of lesion-induced disorders. Results Lesion location was heterogeneous and no single region could be considered necessary for symptom generation. However, over 90% (13/14) of lesions were functionally connected to a focal area in the dorsal medial cerebellum. This cerebellar area overlapped previously recognized regions that are activated by locomotor tasks, termed the cerebellar locomotor region. Connectivity to this region was specific to lesions causing freezing of gait compared to lesions causing other movement disorders (hemichorea or asterixis). Interpretation Lesions causing freezing of gait are located within a common functional network characterized by connectivity to the cerebellar locomotor region. These results based on causal brain lesions complement prior neuroimaging studies in Parkinson’s disease patients, advancing our understanding of the brain regions involved in freezing of gait. PMID:28009063
Li, N G
2016-10-01
Yakutia is a part of eastern Siberia, located in north-eastern Russia. The climate of this area is very harsh even by Siberian standards, and is characterized by the absolute temperature minimum, which is below -64.4 °C, and a long period of low temperatures reaching to a range between -47 and -55 °C. Despite such a severe climate, the fauna and flora of Yakutia present a considerably rich biodiversity, suggesting a high adaptation potential of the organisms in this area. In this study, 30 local species of insects belonging to Coleoptera, Diptera and Lepidoptera were selected to investigate cold adaptation. The identification of the cold adaptation strategy was based on the measurement of the insect body supercooling point (SCP) and hemolymph ice-nucleating activity. According to the data collected, there is a high incidence of freeze tolerant species among the insects found in Yakutsk area (Yakutsk, 62° latitude, 130° longitude): 93.3% of them were freeze tolerant, and only 6.7% were freeze avoiding. It is suggested that the evolution of cold hardiness in this region preferably develops for the selection of the strong freeze tolerance that allow the insects to survive extreme cold conditions. Copyright © 2016 Elsevier Inc. All rights reserved.
Leachate Properties and Cadmium Migration Through Freeze-thaw Treated Soil Columns.
Xu, Meng; Zheng, Yue; Chen, Weiwei; Mao, Na; Guo, Ping
2017-01-01
Soil column leaching experiments were conducted to study the effects of multiple freeze-thaw cycles on the vertical migration of cadmium (Cd). Three Cd-spiked leaching solutions of different properties were derived from snowmelt, sludge, and straw, designated as B, W and J, respectively. The leaching solutions varied in dissolved organic matter (DOM) concentrations in the order of J > W > B. Changes in leachate properties and Cd concentration were observed. The results showed that pH values of all the leachate solutions through freeze-thaw treated soil columns were higher than those of leachates through unfrozen soils. However, electrical conductivity (EC) values decreased compared with leachates in unfrozen treated soil columns. Although the concentrations of DOM in leachate solutions had no evident differences between the freeze-thaw and unfrozen treated soil columns, the concentrations of DOM in the leachate solutions B, W and J were different. Freeze-thaw cycles resulted in increased concentrations of Cd in the leachate solutions in the order J > W > B, and promoted a deeper migration of Cd in the soil columns. Thus, it was shown that freeze-thaw cycles may increase the risk of groundwater pollution by Cd.
Immersion freezing of ice nucleation active protein complexes
NASA Astrophysics Data System (ADS)
Hartmann, S.; Augustin, S.; Clauss, T.; Wex, H.; Šantl-Temkiv, T.; Voigtländer, J.; Niedermeier, D.; Stratmann, F.
2013-06-01
Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS), the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between -5 °C to -38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA) bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about -6 °C to about -10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei) which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a) the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b) the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice nucleation are attached
Henning, Carlo; Poglia, Gabriel; Leie, Murilo Anderson; Galia, Carlos Roberto
2015-12-01
Calcaneal fracture malunion may evolve into arthrosis and severe foot deformities. The aim of this study was to identify differences in bony union following corrective subtalar arthrodesis with interposition of autologous tricortical bone graft or freeze-dried bovine xenograft. We prospectively evaluated 12 patients who underwent subtalar arthrodesis, six patients received autografts and 6 received freeze-dried bovine xenografts. After a mean followup of 58 weeks, the patients were clinical assessed using AOFAS scale and the visual analog scale (VAS) for pain and for final radiographic parameters measurement. Two blind raters evaluated the length of time required for solid union of the arthrodesis and graft integration by retrospective radiographic examination. In the autograft group, AOFAS score improved from a preoperative average of 37 to 64 points postoperatively (p = 0.02) and mean VAS score improved from 4.7 to 1.9 (p = 0.028). In the xenograft group, AOFAS score improved from 38 to 74 points (p = 0.02) and VAS from 5.5 to 2.7 (p = 0.046). Solid union was achieved in all cases in the autograft group at an average of 5.3 weeks and in five cases in the xenograft group at 8.8 weeks (p = 0.077). Graft integration occurred after an average of 10.7 weeks in the autograft group and 28.8 weeks in the xenograft group (p = 0.016). With the numbers available, no significant difference could be detected in the length of time required for solid union of subtalar arthrodesis between groups, although time to integration of freeze-dried bovine xenografts was statistically higher. Clinical and functional improvement was observed in both groups.
9 CFR 381.66 - Temperatures and chilling and freezing procedures.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Temperatures and chilling and freezing... Procedures § 381.66 Temperatures and chilling and freezing procedures. (a) General. Temperatures and... temperature is reduced to 40 °F. or less, as provided in paragraph (b)(2) of this section unless such poultry...
9 CFR 381.66 - Temperatures and chilling and freezing procedures.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Temperatures and chilling and freezing... Procedures § 381.66 Temperatures and chilling and freezing procedures. (a) General. Temperatures and... temperature is reduced to 40 °F. or less, as provided in paragraph (b)(2) of this section unless such poultry...
9 CFR 381.66 - Temperatures and chilling and freezing procedures.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Temperatures and chilling and freezing... Procedures § 381.66 Temperatures and chilling and freezing procedures. (a) General. Temperatures and... temperature is reduced to 40 °F. or less, as provided in paragraph (b)(2) of this section unless such poultry...
Moore, J.N.; Christenson, B.W.; Allis, R.G.; Browne, P.R.L.; Lutz, S.J.
2004-01-01
Acidic steam condensates in volcanic systems or shallow, oxygenated geothermal environments are typically enriched in SO4 and poor in Cl. These fluids produce distinctive alteration-induced assemblages as they descend. At Karaha - Telaga Bodas, located on the flank of Galunggung Volcano, Indonesia, neutralization of descending acid waters has resulted in the successive appearance of 1) advanced argillic alteration characterized by alunite, clay minerals and pyrite, 2) anhydrite, pyrite and interlayered sheet silicates, and 3) carbonates. Minor tourmaline, fluorite and native sulfur also are present locally, reflecting interactions with discharging magmatic gases. Water rock interactions were modeled at temperatures up to 250??C using the composition of acidic lake water from Telaga Bodas and that of a typical andesite as reactants. The simulations predict mineral distributions consistent with the observed assemblages and a decrease in the freezing-point depression of the fluid with increasing temperature. Fluids trapped in anhydrite, calcite and fluorite display a similar decrease in their freezing-point depressions, from 2.8?? to 1.5??C, as homogenization temperatures increase from 160?? to 205??C. The simulations indicate that the progressive change in fluid composition is due mainly to the incorporation of SO4 into the newly formed hydrothermal minerals. The salinities of fluid inclusions containing Cl-deficient steam condensates are better expressed in terms of H2SO4 equivalents than the commonly used NaCl equivalents. At solute concentrations >1.5 molal, freezing-point depressions represented as NaCl equivalents overestimate the salinity of Cl-poor waters. At lower concentrations, differences between apparent salinities calculated as NaCl and H2SO 4 equivalents are negligible.
String-like collective atomic motion in the melting and freezing of nanoparticles.
Zhang, Hao; Kalvapalle, Pranav; Douglas, Jack F
2011-12-08
The melting of a solid represents a transition between a solid state in which atoms are localized about fixed average crystal lattice positions to a fluid state that is characterized by relative atomic disorder and particle mobility so that the atoms wander around the material as a whole, impelled by the random thermal impulses of surrounding atoms. Despite the fundamental nature and practical importance of this particle delocalization transition, there is still no fundamental theory of melting and instead one often relies on the semi-phenomenological Lindemann-Gilvarry criterion to estimate roughly the melting point as an instability of the crystal lattice. Even the earliest simulations of melting in hexagonally packed hard discs by Alder and Wainwright indicated the active role of nonlocal collective atomic motions in the melting process, and here we utilize molecular dynamics (MD) simulation to determine whether the collective particle motion observed in melting has a similar geometrical form as those in recent studies of nanoparticle (NP) interfacial dynamics and the molecular dynamics of metastable glass-forming liquids. We indeed find string-like collective atomic motion in NP melting that is remarkably similar in form to the collective interfacial motions in NPs at equilibrium and to the collective motions found in the molecular dynamics of glass-forming liquids. We also find that the spatial localization and extent of string-like motion in the course of NP melting and freezing evolves with time in distinct ways. Specifically, the collective atomic motion propagates from the NP surface and from within the NP in melting and freezing, respectively, and the average string length varies smoothly with time during melting. In contrast, the string-like cooperative motion peaks in an intermediate stage of the freezing process, reflecting a general asymmetry in the dynamics of NP superheating and supercooling. © 2011 American Chemical Society
Effect of microgravity on material undergoing melting and freezing: The TES Experiment
NASA Astrophysics Data System (ADS)
Namkoong, David; Jacqmin, David; Szaniszlo, Andrew
1995-01-01
This experiment is the first to melt and freeze a high temperature thermal energy storage (TES) material under an extended duration of microgravity. It is one of a series to validate an analytical computer program that predicts void behavior of substances undergoing phase change under microgravity. Two flight experiments were launched in STS-62. The first, TES-1, containing lithium fluoride in an annular volume, performed flawlessly in the 22 hours of its operation. Results are reported in this paper. A software failure in TES-2 caused its shutdown after 4 seconds. A computer program, TESSIM, for thermal energy storage simulation is being developed to analyze the phenomena occurring within the TES containment vessel. The first order effects, particularly the surface tension forces, have been incorporated into TESSIM. TESSIM validation is based on two types of results. First is the temperature history of various points of the containment structure, and second, upon return from flight, the distribution of the TES material within the containment vessel following the last freeze cycle. The temperature data over the four cycles showed a repetition of results over the third and fourth cycles. This result is a confirmation that any initial conditions prior to the first cycle had been damped out by the third cycle. The TESSIM simulation showed a close comparison with the flight data. The solidified TES material distribution within the containment vessel was obtained by a tomography imaging process. The frozen material was concentrated toward the colder end of the annular volume. The TESSIM prediction showed the same pattern. With the general agreement of TESSIM and the data, a computerized visual representation can be shown which accurately shows the movement and behavior of the void during the entire freezing and melting cycles.
Effect of Microgravity on Material Undergoing Melting and Freezing: the TES Experiment
NASA Technical Reports Server (NTRS)
Namkoong, David; Jacqmin, David; Szaniszlo, Andrew
1995-01-01
This experiment is the first to melt and freeze a high temperature thermal energy storage (TES) material under an extended duration of microgravity. It is one of a series to validate an analytical computer program that predicts void behavior of substances undergoing phase change under microgravity. Two flight experiments were launched in STS-62. The first, TES-1, containing lithium fluoride in an annular volume, performed flawlessly in the 22 hours of its operation. Results are reported in this paper. A software failure in TES-2 caused its shutdown after 4 seconds. A computer program, TESSIM, for thermal energy storage simulation is being developed to analyze the phenomena occurring within the TES containment vessel. The first order effects, particularly the surface tension forces, have been incorporated into TESSIM. TESSIM validation is based on two types of results. First is the temperature history of various points of the containment structure, and second, upon return from flight, the distribution of the TES material within the containment vessel following the last freeze cycle. The temperature data over the four cycles showed a repetition of results over the third and fourth cycles. This result is a confirmation that any initial conditions prior to the first cycle had been damped out by the third cycle. The TESSIM simulation showed a close comparison with the flight data. The solidified TES material distribution within the containment vessel was obtained by a tomography imaging process. The frozen material was concentrated toward the colder end of the annular volume. The TESSIM prediction showed the same pattern. With the general agreement of TESSIM and the data, a computerized visual representation can be shown which accurately shows the movement and behavior of the void during the entire freezing and melting cycles.
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.
Depressive symptoms and risk of dementia
Saczynski, J.S.; Beiser, A.; Seshadri, S.; Auerbach, S.; Wolf, P.A.; Au, R.
2010-01-01
Objectives: Depression may be associated with an increased risk for dementia, although results from population-based samples have been inconsistent. We examined the association between depressive symptoms and incident dementia over a 17-year follow-up period. Methods: In 949 Framingham original cohort participants (63.6% women, mean age = 79), depressive symptoms were assessed at baseline (1990-1994) using the 60-point Center for Epidemiologic Studies Depression Scale (CES-D). A cutpoint of ≥16 was used to define depression, which was present in 13.2% of the sample. Cox proportional hazards models adjusting for age, sex, education, homocysteine, and APOE ε4 examined the association between baseline depressive symptoms and the risk of dementia and Alzheimer disease (AD). Results: During the 17-year follow-up period, 164 participants developed dementia; 136 of these cases were AD. A total of 21.6% of participants who were depressed at baseline developed dementia compared with 16.6% of those who were not depressed. Depressed participants (CES-D ≥16) had more than a 50% increased risk for dementia (hazard ratio [HR] 1.72, 95% confidence interval [CI] 1.04-2.84, p = 0.035) and AD (HR 1.76, 95% CI 1.03-3.01, p = 0.039). Results were similar when we included subjects taking antidepressant medications as depressed. For each 10-point increase on the CES-D, there was significant increase in the risk of dementia (HR 1.46, 95% CI 1.18-1.79, p < 0.001) and AD (HR 1.39, 95% CI 1.11-1.75, p = 0.005). Results were similar when we excluded persons with possible mild cognitive impairment. Conclusions: Depression is associated with an increased risk of dementia and AD in older men and women over 17 years of follow-up. GLOSSARY AD = Alzheimer disease; CDR = Clinical Dementia Rating; CES-D = Center for Epidemiologic Studies Depression Scale; CI = confidence interval; DSM-IV = Diagnostic and Statistical Manual of Mental Disorders, 4th edition; HR = hazard ratio; MCI = mild
Exercise as an augmentation strategy for treatment of major depression.
Trivedi, Madhukar H; Greer, Tracy L; Grannemann, Bruce D; Chambliss, Heather O; Jordan, Alexander N
2006-07-01
The use of augmentation strategies among patients with major depression is increasing because rates of complete remission with standard antidepressant monotherapy are quite low. Clinical and neurobiological data suggest that exercise may be a good candidate for use as an augmentation treatment for depression. This pilot study examined the use of exercise to augment antidepressant medication in patients with major depression. Seventeen patients with incomplete remission of depressive symptoms began a 12-week exercise program while continuing their antidepressant medication (unchanged in type or dose). Individual exercise prescriptions were calculated based on an exercise dose consistent with currently recommended public health guidelines. The exercise consisted of both supervised and home-based sessions. The 17-item Hamilton Rating Scale for Depression (HRSD17) and the Inventory of Depressive Symptomatology-Self-Report (IDS-SR30) were used to assess symptoms of depression on a weekly basis. Intent-to-treat analyses yielded significant decreases on both the HRSD17 (5.8 points, p < 0.008) and IDS-SR30 (13.9 points, p < 0.002). For patients who completed the study (n = 8), HRSD17 scores decreased by 10.4 points and IDS-SR30 scores decreased by 18.8 points. This study provides preliminary evidence for exercise as an effective augmentation treatment for antidepressant medication. This is a lower-cost augmentation strategy that has numerous health benefits and may further reduce depressive symptoms in partial responders to antidepressant treatment. Practical tips on how practitioners can use exercise to enhance antidepressant treatment are discussed. Longer-term use of exercise is also likely to confer additional health benefits for this population.
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Allgaier, Antje-Kathrin; Krick, Kathrin; Opitz, Ansgar; Saravo, Barbara; Romanos, Marcel; Schulte-Körne, Gerd
2014-07-30
Diagnosing childhood depression can pose a challenge, even for mental health specialists. Screening tools can aid clinicians within the initial step of the diagnostic process. For the first time, the Children׳s Depression Screener (ChilD-S) is validated in a mental health setting as a novel field of application beyond the previously examined pediatric setting. Based on a structured interview, DSM-IV-TR diagnoses of depression were made for 79 psychiatric patients aged 9-12, serving as the gold standard for validation. For assessing criterion validity, receiver operating characteristic (ROC) curves were calculated. Point prevalence of major depression and dysthymia was 28%. Diagnostic accuracy in terms of the area under the ROC curve was high (0.97). At the optimal cut-off point ≥12 according to the Youden׳s index, sensitivity was 0.91 and specificity was 0.81. The findings suggest that the ChilD-S is not only a valid screening instrument for childhood depression in pediatric care but also in mental health settings. As a brief tool it can easily be implemented into daily clinical practice of mental health professionals facilitating the diagnostic process, especially in case of comorbid depression. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Women's status and depressive symptoms: a multilevel analysis.
Chen, Ying-Yeh; Subramanian, S V; Acevedo-Garcia, Doloros; Kawachi, Ichiro
2005-01-01
The effects of state-level women's status and autonomy on individual-level women's depressive symptoms were examined. We conducted a multi-level analysis of the 1991 longitudinal follow up of the 1988 National Maternal Infant Health Survey (NMIHS), with 7789 women nested within the fifty American states. State-level women's status was assessed by four composite indices measuring women's political participation, economic autonomy, employment & earnings, and reproductive rights. The main outcome measure was symptoms of depression (Center for Epidemiologic Studies Depression Scale, CES-D). The participants were a nationally representative stratified random sample of women in the USA aged between 17 and 40 years old who gave birth to live babies in 1988, were successfully contacted again in 1991 and provided complete information on depressive symptoms. Women who were younger, non-white, not currently married, less educated or had lower household income tended to report higher levels of depressive symptoms. Compared with states ranking low on the employment & earnings index, women residing in states that were high on the same index scored 0.85 points lower on the CES-D (p<0.01). Women who lived in states that were high on the economic autonomy index scored 0.83 points lower in depressive symptoms (p<0.01), compared with women who lived in states low on the same index. Finally, women who resided in states with high reproductive rights scored 0.62 points lower on the CES-D (p<0.05) compared with women who lived in states with lower reproductive rights. Gender inequality appears to contribute to depressive symptoms in women.
Kim, Yuan H Brad; Liesse, Charlotte; Kemp, Robert; Balan, Prabhu
2015-12-01
The objective of our study was to evaluate the combined effects of ageing period and different freezing rates on meat quality attributes of beef loins. Pairs of loins (M. longissimus at 1 day post mortem) from 12 carcasses were divided into four equal portions and randomly assigned to four ageing/freezing treatments (aged only, frozen only, and 3 or 4 weeks ageing at -1.5°C then frozen). Two freezing methods (fast freezing by calcium chloride immersion or slow freezing by air freezer at -18°C) were applied to the loin sections. Fast freezing had no effect on shear force (P>0.05), but significantly improved the water-holding capacity of the aged/frozen loins by reducing purge and drip losses. Ageing-then-freezing significantly improved shear force values of loins compared to both the aged only and frozen only loins. These observations suggest that fast freezing will add more value to the aged/frozen/thawed meat by minimising the amount of water-loss due to the freezing/thawing process. Copyright © 2015 Elsevier Ltd. All rights reserved.
The effect of dryer load on freeze drying process design.
Patel, Sajal M; Jameel, Feroz; Pikal, Michael J
2010-10-01
Freeze-drying using a partial load is a common occurrence during the early manufacturing stages when insufficient amounts of active pharmaceutical ingredient (API) are available. In such cases, the immediate production needs are met by performing lyophilization with less than a full freeze dryer load. However, it is not obvious at what fractional load significant deviations from full load behavior begin. The objective of this research was to systematically study the effects of variation in product load on freeze drying behavior in laboratory, pilot and clinical scale freeze-dryers. Experiments were conducted with 5% mannitol (high heat and mass flux) and 5% sucrose (low heat and mass flux) at different product loads (100%, 50%, 10%, and 2%). Product temperature was measured in edge as well as center vials with thermocouples. Specific surface area (SSA) was measured by BET gas adsorption analysis and residual moisture was measured by Karl Fischer. In the lab scale freeze-dryer, the molar flux of inert gas was determined by direct flow measurement using a flowmeter and the molar flux of water vapor was determined by manometric temperature measurement (MTM) and tunable diode laser absorption spectroscopy (TDLAS) techniques. Comparative pressure measurement (capacitance manometer vs. Pirani) was used to determine primary drying time. For both 5% mannitol and 5% sucrose, primary drying time decreases and product temperature increases as the load on the shelves decreases. No systematic variation was observed in residual moisture and vapor composition as load decreased. Further, SSA data suggests that there are no significant freezing differences under different load conditions. Independent of dryer scale, among all the effects, variation in radiation heat transfer from the chamber walls to the product seems to be the dominant effect resulting in shorter primary drying time as the load on the shelf decreases (i.e., the fraction of edge vials increases).
Parents' Depressive Symptoms and Gun, Fire, and Motor Vehicle Safety Practices.
Morrissey, Taryn W
2016-04-01
This study examined associations between mothers' and fathers' depressive symptoms and their parenting practices relating to gun, fire, and motor vehicle safety. Using data from the Early Childhood Longitudinal Study-Birth Cohort (ECLS-B), a nationally representative sample of children birth to age five, linear probability models were used to examine associations between measures of parents' depressive symptoms and their use of firearms, smoke detectors, and motor vehicle restraints. Parents reported use of smoke detectors, motor vehicle restraints, and firearm ownership and storage. Results suggest mothers with moderate or severe depressive symptoms were 2 % points less likely to report that their child always sat in the back seat of the car, and 3 % points less likely to have at least one working smoke detector in the home. Fathers' depressive symptoms were associated with a lower likelihood of both owning a gun and of it being stored locked. Fathers' depressive symptoms amplified associations between mothers' depressive symptoms and owning a gun, such that having both parents exhibit depressive symptoms was associated with an increased likelihood of gun ownership of between 2 and 6 % points. Interventions that identify and treat parental depression early may be effective in promoting appropriate safety behaviors among families with young children.
Freeze-all cycle in reproductive medicine: current perspectives
Roque, Matheus; Valle, Marcello; Kostolias, Alessandra; Sampaio, Marcos; Geber, Selmo
2017-01-01
The freeze-all strategy has emerged as an alternative to fresh embryo transfer (ET) during in vitro fertilization (IVF) cycles. Although fresh ET is the norm during assisted reproductive therapies (ART), there are many concerns about the possible adverse effects of controlled ovarian stimulation (COS) over the endometrium. The supra-physiologic hormonal levels that occur during a conventional COS are associated with modifications in the peri-implantation endometrium, which may be related to a decrease in pregnancy rates and poorer obstetric and perinatal outcomes when comparing fresh to frozen-thawed embryo transfers. The main objective of this study was to assess the available literature regarding the freeze-all strategy in IVF cycles, in regards to effectiveness and safety. Although there are many potential advantages in performing a freeze-all cycle over a fresh ET, it seems that the freeze-all strategy is not designed for all IVF patients. There is a need to develop a non-invasive clinical tool to evaluate the endometrial receptivity during a fresh cycle, which enables the selection of patients that would benefit from this strategy. Today, it is reasonable to perform elective cryopreservation of all oocytes/embryos in cases with a risk of OHSS development, and in patients with supra-physiologic hormonal levels during the follicular phase of COS. It is not clear if all normal responders and poor responders may benefit from this strategy. PMID:28333033
Administration of ketamine for unipolar and bipolar depression.
Kraus, Christoph; Rabl, Ulrich; Vanicek, Thomas; Carlberg, Laura; Popovic, Ana; Spies, Marie; Bartova, Lucie; Gryglewski, Gregor; Papageorgiou, Konstantinos; Lanzenberger, Rupert; Willeit, Matthäus; Winkler, Dietmar; Rybakowski, Janusz K; Kasper, Siegfried
2017-03-01
Clinical trials demonstrated that ketamine exhibits rapid antidepressant efficacy when administered in subanaesthetic dosages. We reviewed currently available literature investigating efficacy, response rates and safety profile. Twelve studies investigating unipolar, seven on bipolar depression were included after search in medline, scopus and web of science. Randomized, placebo-controlled or open-label trials reported antidepressant response rates after 24 h on primary outcome measures at 61%. The average reduction of Hamilton Depression Rating Scale (HAM-D) was 10.9 points, Beck Depression Inventory (BDI) 15.7 points and Montgomery-Asberg Depression Rating Scale (MADRS) 20.8 points. Ketamine was always superior to placebo. Most common side effects were dizziness, blurred vision, restlessness, nausea/vomiting and headache, which were all reversible. Relapse rates ranged between 60% and 92%. To provide best practice-based information to patients, a consent-form for application and modification in local language is included. Ketamine constitutes a novel, rapid and efficacious treatment option for patients suffering from treatment resistant depression and exhibits rapid and significant anti-suicidal effects. New administration routes might serve as alternative to intravenous regimes for potential usage in outpatient settings. However, long-term side effects are not known and short duration of antidepressant response need ways to prolong ketamine's efficacy.
Multiscale model of a freeze-thaw process for tree sap exudation.
Graf, Isabell; Ceseri, Maurizio; Stockie, John M
2015-10-06
Sap transport in trees has long fascinated scientists, and a vast literature exists on experimental and modelling studies of trees during the growing season when large negative stem pressures are generated by transpiration from leaves. Much less attention has been paid to winter months when trees are largely dormant but nonetheless continue to exhibit interesting flow behaviour. A prime example is sap exudation, which refers to the peculiar ability of sugar maple (Acer saccharum) and related species to generate positive stem pressure while in a leafless state. Experiments demonstrate that ambient temperatures must oscillate about the freezing point before significantly heightened stem pressures are observed, but the precise causes of exudation remain unresolved. The prevailing hypothesis attributes exudation to a physical process combining freeze-thaw and osmosis, which has some support from experimental studies but remains a subject of active debate. We address this knowledge gap by developing the first mathematical model for exudation, while also introducing several essential modifications to this hypothesis. We derive a multiscale model consisting of a nonlinear system of differential equations governing phase change and transport within wood cells, coupled to a suitably homogenized equation for temperature on the macroscale. Numerical simulations yield stem pressures that are consistent with experiments and provide convincing evidence that a purely physical mechanism is capable of capturing exudation. © 2015 The Author(s).