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Sample records for cell freeze liquid

  1. Liquid carbon: structure near the freezing line

    NARCIS (Netherlands)

    Ghiringhelli, L.M.; Los, J.H.; Meijer, E.J.; Fasolino, A.; Frenkel, D.

    2005-01-01

    We present a detailed analysis of the structure of liquid carbon near the freezing line. The results are obtained by molecular simulation using a recently developed state-of-the-art bond order potential. We find that along the melting line the liquid is predominantly threefold coordinated up to pres

  2. Freezing mammalian cells for production of biopharmaceuticals.

    Science.gov (United States)

    Seth, Gargi

    2012-03-01

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

  3. Deformed liquid marbles: Freezing drop oscillations with powders

    KAUST Repository

    Marston, Jeremy

    2012-09-01

    In this work we show that when a liquid drop impacts onto a fine-grained hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. In all cases, the drop rebounds due to the hydrophobic nature of the powder. However, we find that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a near-complete coverage of powder, which then freezes the drop oscillations during rebound. © 2012 Elsevier B.V.

  4. Fast-freezing with liquid nitrogen preserves bulk dissolved organic matter concentrations, but not its composition

    Science.gov (United States)

    Thieme, Lisa; Graeber, Daniel; Kaupenjohann, Martin; Siemens, Jan

    2016-08-01

    Freezing can affect concentrations and spectroscopic properties of dissolved organic matter (DOM) in water samples. Nevertheless, water samples are regularly frozen for sample preservation. In this study we tested the effect of different freezing methods (standard freezing at -18 °C and fast-freezing with liquid nitrogen) on DOM concentrations measured as organic carbon (DOC) concentrations and on spectroscopic properties of DOM from different terrestrial ecosystems (forest and grassland). Fresh and differently frozen throughfall, stemflow, litter leachate and soil solution samples were analyzed for DOC concentrations, UV-vis absorption and fluorescence excitation-emission matrices combined with parallel factor analysis (PARAFAC). Fast-freezing with liquid nitrogen prevented a significant decrease of DOC concentrations observed after freezing at -18 °C. Nonetheless, the share of PARAFAC components 1 (EXmax nitrogen for preservation of bulk DOC concentrations of samples from terrestrial sources, whereas immediate measuring is preferable to preserve spectroscopic properties of DOM.

  5. Fast-freezing with liquid nitrogen preserves bulk dissolved organic matter concentrations, but not its composition

    DEFF Research Database (Denmark)

    Thieme, Lisa; Graeber, Daniel; Kaupenjohann, Martin;

    2016-01-01

    Freezing can affect concentrations and spectroscopic properties of dissolved organic matter (DOM) in water samples. Nevertheless, water samples are regularly frozen for sample preservation. In this study we tested the effect of different freezing methods (standard freezing at −18 °C and fast......-freezing with liquid nitrogen) on DOM concentrations measured as organic carbon (DOC) concentrations and on spectroscopic properties of DOM from different terrestrial ecosystems (forest and grassland). Fresh and differently frozen throughfall, stemflow, litter leachate and soil solution samples were analyzed...... spectroscopic properties of DOM....

  6. PEM Fuel Cell Freeze Durability and Cold Start Project

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, T.; O' Neill, Jonathan

    2008-01-02

    UTC has taken advantage of the unique water management opportunities inherent in micro-porous bipolar-plates to improve the cold-start performance of its polymer electrolyte fuel cells (PEFC). Diagnostic experiments were used to determine the limiting factors in micro-porous plate PEFC freeze performance and the causes of any performance decay. Alternative cell materials were evaluated for their freeze performance. Freeze-thaw cycling was also performed to determine micro-porous plate PEFC survivability. Data from these experiments has formed the basis for continuing development of advanced materials capable of supporting DOE's cold-start and durability objectives.

  7. Use of liquid nitrogen to freeze rocks in shaft collar construction

    Energy Technology Data Exchange (ETDEWEB)

    Vyal' tsev, M.M.; Agishev, V.V.

    1984-04-01

    This paper describes the process by which loam was frozen to protect the collar of an air shaft in a Donbass mine in 1982. The shaft, 6 m internal diameter, was excavated to about 15 m, but influxes of watery loam could not be prevented by either reinforced concrete or metal tubbing sections. Boreholes for local freezing were drilled with an SBA-500 unit fanwise into the shaft walls. The freezing boreholes were 11 m long. A description of the distribution of the 9 freezing sections is given, in each of which were a 108 mm gas pipe and 89 mm liquid and vapor/liquid pipes. The liquid nitrogen was pumped in from tankers at the surface via a 53 mm pipe. Four monitoring boreholes with remote control sensors were used to check the rock temperature. The freezing process (to a thickness of 55 cm) took 9 days and 250 t of nitrogen, and represented a savings of 150 man days. The strength of the frozen rocks was 3.5-4 times greater than for brine freezing, so that the thickness of the frozen layer could be halved. (In Russian)

  8. Determination of cell volume during equilibrium freezing process

    Institute of Scientific and Technical Information of China (English)

    ZHAO Gang; GAO Dayong; HE Liqun; WANG Peitao; DING Weiping; XIE Xiaojian; LIU Zhong; ZHANG Haifeng; SHU Zhiquan; LUO Dawei

    2003-01-01

    A new type electronic particle counter (EPC, MultisizerTM 3, Beckman Coulter Inc., USA) was used to determine the volumes of human red blood cells (RBCs) in NaCl solutions of different osmolalities. The thermodynamics model describing cell response during freezing process was used to simulate the volume change of RBC in 0.9% NaCl solution during equilibrium freezing process. It was assumed that the effect of temperature on cell volume can be neglected compared to that of osmolality, then by using the phase diagram for the binary system sodium chloride/water, the osmolalities of the NaCl solution under different sub-zero temperatures can be obtained (converted from mass concentration), then the calculated values of RBC volumes can be validated by the experiments.

  9. A model of freezing foods with liquid nitrogen using special functions

    Science.gov (United States)

    Rodríguez Vega, Martín.

    2014-05-01

    A food freezing model is analyzed analytically. The model is based on the heat diffusion equation in the case of cylindrical shaped food frozen by liquid nitrogen; and assuming that the thermal conductivity of the cylindrical food is radially modulated. The model is solved using the Laplace transform method, the Bromwich theorem, and the residue theorem. The temperature profile in the cylindrical food is presented as an infinite series of special functions. All the required computations are performed with computer algebra software, specifically Maple. Using the numeric values of the thermal and geometric parameters for the cylindrical food, as well as the thermal parameters of the liquid nitrogen freezing system, the temporal evolution of the temperature in different regions in the interior of the cylindrical food is presented both analytically and graphically. The duration of the liquid nitrogen freezing process to achieve the specified effect on the cylindrical food is computed. The analytical results are expected to be of importance in food engineering and cooking engineering. As a future research line, the formulation and solution of freezing models with thermal memory is proposed.

  10. Comparison of conventional and directional freezing for the cryopreservation of human umbilical vein endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Bing; Qi; Qing-Shan; Ji; Guang-Hui; Hou; Liu; Li; Xian-Fen; Cao; Jing; Wu

    2014-01-01

    AIM:To compare conventional slow equilibrium cooling and directional freezing(DF) by gauze package for cryopreservation of human umbilical vein endothelial cells(HUVECs).METHODS:HUVECs were randomly assigned to conventional freezing(CF) and DF by gauze package group. The two groups of HUVECs were incubated with a freezing liquid consisting of 10% dimethylsulfoxide(DMSO), 60% fetal bovine serum(FBS) and 30%Dulbecco’s modified Eagle’s medium(DMEM) and then put into cryopreserved tubes. CF group, slow equilibrium cooling was performed with the following program:precool in 4℃ for 30 min,-20℃ for 1h, and then immersion in-80℃ refrigerator. DF group, the tubes were packaged with gauze and then directional freezing in-80℃ refrigerator straightly. One month later, the vitality of HUVECs were calculated between two groups.RESULTS:There was no significant difference in the survival rate and growth curve between CF and DF groups. The DF group was significantly better than CFgroup in adherent rates, morphological changes and proliferative ability.CONCLUSION:In the conventional cryopreserved method, cells are slow equilibrium cooling by steps(4℃,-20℃ and finally-80℃), which is a complicated and time-consuming process. But the improved DF by gauze package method is better than conventional method, for which is convenient and easy to operate.

  11. Generalized structural theory of freezing

    International Nuclear Information System (INIS)

    The first-principles order parameter theory of freezing, proposed in an earlier work, has been successful in yielding quantitative agreement with known freezing parameters for monoatomic liquids forming solids with one atom per unit cell. A generalization of this theory is presented here to include the effects of a basis set of many atoms per unit cell. The basic equations get modified by the 'density structure factors' fsub(i) which arise from the density variations within the unit cell. Calculations are presented for the important case of monoatomic liquids freezing into hexagonal close packed solids. It is concluded that all freezing transitions can be described by using structural correlations in the liquid instead of the pair potential; and that the three body correlations are important in deciding the type of solid formed after freezing. (author)

  12. High throughput cryopreservation of cells by rapid freezing of sub-μl drops using inkjet printing--cryoprinting.

    Science.gov (United States)

    Dou, Rui; Saunders, Rachel E; Mohamet, Lisa; Ward, Christopher M; Derby, Brian

    2015-09-01

    We have successfully used inkjet printing to cryopreserve 3T3 mouse fibroblast cells and human neuroprogenitor cells (NPCs) derived from human embryonic stem cells (hESCs). Sessile drops of volume 114 nl were formed by printing cell suspensions containing dimethyl sulphoxide (DMSO) as a cryoprotection agent (CPA) at rates in the region 100 Hz-20 kHz, from individual droplets of 380 pl. After printing and a freeze/thaw cycle (with a minimum 24 hours hold period at liquid N2 temperature), 3T3 cells showed an average viability of >90% with CPA concentration polyimide substrate. The viability of 3T3 cells after 2 months storage at liquid nitrogen temperature was slightly reduced compared to the cells held for 24 hours but there was no significant further deterioration after 4 or 6 months storage. The viability of NPCs after an identical freeze/thaw cycle were only 55% but this is comparable with conventional cryopreservation methods that use much higher CPA concentrations. A parallel series of experiments printing cells onto substrates held at 195 K or directly into liquid N2 showed considerable variation in cell survival rate with drop deposition rate. Cell suspensions required higher levels of CPA than when printing followed by freezing. At low deposition rates a combination of DMSO and polyethylene glycol (PEG) was needed to allow cell viability after freezing. These results show that inkjet printing provides a practical high throughput method for the cryopreservation of cells with lower CPA concentrations than are required for current low volume cryopreservation methods. PMID:26190571

  13. Spin freezing in the spin-liquid compound FeAl2O4

    Science.gov (United States)

    Nair, Harikrishnan S.; Ramesh Kumar, K.; Strydom, André M.

    2015-02-01

    Spin freezing in the A -site spinel FeAl2O4 , which is a spin-liquid candidate, is studied using remnant magnetization and nonlinear magnetic susceptibility and isofield cooling and heating protocols. The remnant magnetization behavior of FeAl2O4 differs significantly from that of a canonical spin glass, which is also supported by analysis of the nonlinear magnetic susceptibility term χ3(T ) . Through the power-law analysis of χ3(T ) , a spin-freezing temperature Tg=11.4 ±0.9 K and critical exponent γ =1.48 ±0.59 are obtained. A Cole-Cole analysis of magnetic susceptibility shows the presence of broad spin relaxation times in FeAl2O4 , however, the irreversible dc susceptibility plot discourages an interpretation based on conventional spin-glass features. The magnetization measured using the cooling-and-heating-in-unequal-fields protocol brings more insight into the magnetic nature of this frustrated magnet and reveals unconventional glassy behavior. Combining our results, we arrive at the conclusion that the present sample of FeAl2O4 consists of a majority spin-liquid phase with "glassy" regions embedded.

  14. 21 CFR 864.9225 - Cell-freezing apparatus and reagents for in vitro diagnostic use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cell-freezing apparatus and reagents for in vitro diagnostic use. 864.9225 Section 864.9225 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH... Establishments That Manufacture Blood and Blood Products § 864.9225 Cell-freezing apparatus and reagents for...

  15. Intracellular trehalose improves the survival of human red blood cells by freeze-drying

    Institute of Scientific and Technical Information of China (English)

    HE Hui; LIU Baolin; HUA Zezhao; LI Chuan; WU Zhengzheng

    2007-01-01

    Freeze-drying of human red blood cells has a potential important application for blood transfusion.The aim of this study was to investigate the effects ofintracellular trehalose on the survival of red blood cells after freeze-drying and rehydration.Fresh red blood cells were incubated in trehalose solutions of various concentrations at 37℃ for 7 h following freeze-drying.Polyvinylpyrrolidone,Trehalose,sodium citrate,and human serum albumin were used as extracellular protective agents for the freeze-drying of red blood cells.The results indicated that the intracellular trehalose concentration was increased with increasing concentration of extracellular trehalose solution,and the maximum concen tration of intracellular trehalose reached 35 mmol/L.The viability of freeze-dried red blood cells increased with the increment of intracellular trehalose concentration.

  16. Liquid fuel cells.

    Science.gov (United States)

    Soloveichik, Grigorii L

    2014-01-01

    The advantages of liquid fuel cells (LFCs) over conventional hydrogen-oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented.

  17. Roles of the plasma membrane and the cell wall in the responses of plant cells to freezing.

    Science.gov (United States)

    Yamada, Tomoyoshi; Kuroda, Katsushi; Jitsuyama, Yutaka; Takezawa, Daisuke; Arakawa, Keita; Fujikawa, Seizo

    2002-09-01

    In an effort to clarify the responses of a wide range of plant cells to freezing, we examined the responses to freezing of the cells of chilling-sensitive and chilling-resistant tropical and subtropical plants. Among the cells of the plants that we examined, those of African violet ( Saintpaulia grotei Engl.) leaves were most chilling-sensitive, those of hypocotyls in mungbean [ Vigna radiata (L.) R. Wilcz.] seedlings were moderately chilling-sensitive, and those of orchid [ Paphiopedilum insigne (Wallich ex Lindl.) Pfitz.] leaves were chilling-resistant, when all were chilled at -2 degrees C. By contrast, all these plant cells were freezing-sensitive and suffered extensive damage when they were frozen at -2 degrees C. Cryo-scanning electron microscopy (Cryo-SEM) confirmed that, upon chilling at -2 degrees C, both chilling-sensitive and chilling-resistant plant cells were supercooled. Upon freezing at -2 degrees C, by contrast, intracellular freezing occurred in Saintpaulia leaf cells, frost plasmolysis followed by intracellular freezing occurred in mungbean seedling cells, and extracellular freezing (cytorrhysis) occurred in orchid leaf cells. We postulate that chilling-related destabilization of membranes might result in the loss of the ability of the plasma membrane to act as a barrier against the propagation of extracellular ice in chilling-sensitive plant cells. We also examined the role of cell walls in the response to freezing using cells in which the plasma membrane had been disrupted by repeated freezing and thawing. In chilling-sensitive Saintpaulia and mungbean cells, the cells with a disrupted plasma membrane responded to freezing at -2 degrees C by intracellular freezing. By contrast, in chilling-resistant orchid cells, as well as in other cells of chilling-resistant and freezing-resistant plant tissues, including leaves of orchard grass ( Dactylis glomerata L.), leaves of Arabidopsis thaliana (L.) Heynh. and cortical tissues of mulberry ( Morus

  18. Chemistry in the Venus clouds: Sulfuric acid reactions and freezing behavior of aqueous liquid droplets

    Science.gov (United States)

    Delitsky, M. L.; Baines, K. H.

    2015-11-01

    Venus has a thick cloud deck at 40-70 km altitude consisting of liquid droplets and solid particles surrounded by atmospheric gases. The liquid droplets are highly concentrated aqueous solutions of sulfuric acid ranging in concentration from 70-99 wt%. Weight percent drops off with altitude (Imamura and Hashimoto 2001). There will be uptake of atmospheric gases into the droplet solutions and the ratios of gas-phase to liquid-phase species will depend on the Henry’s Law constant for those solutions. Reactions of sulfuric acid with these gases will form products with differing solubilities. For example, uptake of HCl by H2SO4/H2O droplets yields chlorosulfonic acid, ClSO3H (Robinson et al 1998) in solution. This may eventually decompose to thionyl- or sulfuryl chlorides, which have UV absorbances. HF will also uptake, creating fluorosulfonic acid, FSO3H, which has a greater solubility than the chloro- acid. As uptake continues, there will be many dissolved species in the cloudwaters. Baines and Delitsky (2013) showed that uptake will have a maximum at ~62 km and this is very close to the reported altitude for the mystery UV absorber in the Venus atmosphere. In addition, at very strong concentrations in lower altitude clouds, sulfuric acid will form hydrates such as H2SO4.H2O and H2SO4.4H2O which will have very different freezing behavior than sulfuric acid, with much higher freezing temperatures (Carslaw et al, 1997). Using temperature data from Venus Express from Tellmann et al (2009), and changes in H2SO4 concentrations as a function of altitude (James et al 1997), we calculate that freezing out of sulfuric acid hydrates can be significant down to as low as 56 km altitude. As a result, balloons, aircraft or other probes in the Venus atmosphere may be limited to flying below certain altitudes. Any craft flying at altitudes above ~55 km may suffer icing on the wings, propellers, balloons and instruments which could cause possible detrimental effects (thermal

  19. [Effect of inert gas xenon on the functional state of nucleated cells of peripheral blood during freezing].

    Science.gov (United States)

    Laptev, D S; Polezhaeva, T V; Zaitseva, O O; Khudyakov, A N; Utemov, S V; Knyazev, M G; Kostyaev, A A

    2015-01-01

    A new method of preservation of nucleated cells in the electric refrigerator with xenon. After slow freezing and storage is even one day at -80 °C persists for more than 60% leukocytes. Cell membranes are resistant to the vital dye. In 85% of granulocytes stored baseline lysosomal-cationic protein, reduced lipid peroxidation and antioxidant activity. Cryopreservation of biological objects in inert gases is a promising direction in the practice of medicine and can be an alternative to the traditional method using liquid nitrogen. PMID:26027341

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

    Science.gov (United States)

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

    1993-01-01

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

  1. An improved model for nucleation-limited ice formation in living cells during freezing.

    Directory of Open Access Journals (Sweden)

    Jingru Yi

    Full Text Available Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF, our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1. We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, i.e., surface-catalyzed nucleation (SCN and volume-catalyzed nucleation (VCN. Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications.

  2. An improved model for nucleation-limited ice formation in living cells during freezing.

    Science.gov (United States)

    Yi, Jingru; Liang, Xin M; Zhao, Gang; He, Xiaoming

    2014-01-01

    Ice formation in living cells is a lethal event during freezing and its characterization is important to the development of optimal protocols for not only cryopreservation but also cryotherapy applications. Although the model for probability of ice formation (PIF) in cells developed by Toner et al. has been widely used to predict nucleation-limited intracellular ice formation (IIF), our data of freezing Hela cells suggest that this model could give misleading prediction of PIF when the maximum PIF in cells during freezing is less than 1 (PIF ranges from 0 to 1). We introduce a new model to overcome this problem by incorporating a critical cell volume to modify the Toner's original model. We further reveal that this critical cell volume is dependent on the mechanisms of ice nucleation in cells during freezing, i.e., surface-catalyzed nucleation (SCN) and volume-catalyzed nucleation (VCN). Taken together, the improved PIF model may be valuable for better understanding of the mechanisms of ice nucleation in cells during freezing and more accurate prediction of PIF for cryopreservation and cryotherapy applications. PMID:24852166

  3. Cryopreservation of Endothelial Cells in Various Cryoprotective Agents and Media - Vitrification versus Slow Freezing Methods.

    Directory of Open Access Journals (Sweden)

    Achim von Bomhard

    Full Text Available Vitrification of endothelial cells (MHECT-5 has not previously been compared with controlled slow freezing methods under standardized conditions. To identify the best cryopreservation technique, we evaluated vitrification and standardized controlled-rate -1°C/minute cell freezing in a -80°C freezer and tested four cryoprotective agents (CPA, namely dimethyl sulfoxide (DMSO, ethylene glycol (EG, propylene glycol (PG, and glycerol (GLY, and two media, namely Dulbecco's modified Eagle medium Ham's F-12 (DMEMand K+-modified TiProtec (K+TiP, which is a high-potassium-containing medium. Numbers of viable cells in proliferation were evaluated by the CellTiter 96® AQueous One Solution Cell Proliferation Assay (Promega Corporation, Mannheim, Germany. To detect the exact frozen cell number per cryo vial, DNA content was measured by using Hoechst 33258 dye prior to analysis. Thus, results could be evaluated unconstrained by absolute cell number. Thawed cells were cultured in 25 cm2 cell culture flasks to confluence and examined daily by phase contrast imaging. With regard to cell recovery immediately after thawing, DMSO was the most suitable CPA combined with K+TiP in vitrification (99 ±0.5% and with DMEM in slow freezing (92 ±1.6%. The most viable cells in proliferation after three days of culture were obtained in cells vitrificated by using GLY with K+TiP (308 ±34% and PG with DMEM in slow freezing (280 ±27%.

  4. Freezing resistance in Patagonian woody shrubs: the role of cell wall elasticity and stem vessel size.

    Science.gov (United States)

    Zhang, Yong-Jiang; Bucci, Sandra J; Arias, Nadia S; Scholz, Fabian G; Hao, Guang-You; Cao, Kun-Fang; Goldstein, Guillermo

    2016-08-01

    Freezing resistance through avoidance or tolerance of extracellular ice nucleation is important for plant survival in habitats with frequent subzero temperatures. However, the role of cell walls in leaf freezing resistance and the coordination between leaf and stem physiological processes under subzero temperatures are not well understood. We studied leaf and stem responses to freezing temperatures, leaf and stem supercooling, leaf bulk elastic modulus and stem xylem vessel size of six Patagonian shrub species from two sites (plateau and low elevation sites) with different elevation and minimum temperatures. Ice seeding was initiated in the stem and quickly spread to leaves, but two species from the plateau site had barriers against rapid spread of ice. Shrubs with xylem vessels smaller in diameter had greater stem supercooling capacity, i.e., ice nucleated at lower subzero temperatures. Only one species with the lowest ice nucleation temperature among all species studied exhibited freezing avoidance by substantial supercooling, while the rest were able to tolerate extracellular freezing from -11.3 to -20 °C. Leaves of species with more rigid cell walls (higher bulk elastic modulus) could survive freezing to lower subzero temperatures, suggesting that rigid cell walls potentially reduce the degree of physical injury to cell membranes during the extracellular freezing and/or thaw processes. In conclusion, our results reveal the temporal-spatial ice spreading pattern (from stem to leaves) in Patagonian shrubs, and indicate the role of xylem vessel size in determining supercooling capacity and the role of cell wall elasticity in determining leaf tolerance of extracellular ice formation. PMID:27217529

  5. FREEZE PROFILE AND HEAT BALANCE CALCULATION OF THE 160kA DRAINED CELL

    Institute of Scientific and Technical Information of China (English)

    X.P.Li; J.Li; Y.Q.Lai; H.Q.Zhao; Y.X.Liu

    2004-01-01

    A 2D full cell thermo-electric model of 160kA drained cell was set up using finite element code to calculate its freeze profile,then the drained cell model was modified according to the freeze profile computed and its heat balance was calculated.Compared with that of a 160kA conventional Hall-Heroult cell(H-H cell),though the melts volume of the drained cell reduced greatly,the whole heat loss from it didn't drop down apparently,and an analysis was presented in the paper.On the other hand,the anodecathode distance(ACD)of a drained cell was much less than that of a H-H cell,so the voltage drop on it and heat produced decreased too,steps should be taken to keep a workable heat balance on a drained cell.

  6. The contribution of apoptosis and necrosis in freezing injury of sea urchin embryonic cells.

    Science.gov (United States)

    Boroda, Andrey V; Kipryushina, Yulia O; Yakovlev, Konstantin V; Odintsova, Nelly A

    2016-08-01

    Sea urchins have recently been reported to be a promising tool for investigations of oxidative stress, UV light perturbations and senescence. However, few available data describe the pathway of cell death that occurs in sea urchin embryonic cells after cryopreservation. Our study is focused on the morphological and functional alterations that occur in cells of these animals during the induction of different cell death pathways in response to cold injury. To estimate the effect of cryopreservation on sea urchin cell cultures and identify the involved cell death pathways, we analyzed cell viability (via trypan blue exclusion test, MTT assay and DAPI staining), caspase activity (via flow cytometry and spectrophotometry), the level of apoptosis (via annexin V-FITC staining), and cell ultrastructure alterations (via transmission electron microscopy). Using general caspase detection, we found that the level of caspase activity was low in unfrozen control cells, whereas the number of apoptotic cells with activated caspases rose after freezing-thawing depending on cryoprotectants used, also as the number of dead cells and cells in a late apoptosis. The data using annexin V-binding assay revealed a very high apoptosis level in all tested samples, even in unfrozen cells (about 66%). Thus, annexin V assay appears to be unsuitable for sea urchin embryonic cells. Typical necrotic cells with damaged mitochondria were not detected after freezing in sea urchin cell cultures. Our results assume that physical cell disruption but not freezing-induced apoptosis or necrosis is the predominant reason of cell death in sea urchin cultures after freezing-thawing with any cryoprotectant combination. PMID:27364314

  7. Slow processes in viscous liquids: Stress and structural relaxation, chemical reaction freezing, crystal nucleation and microemulsion arrest, in relation to liquid fragility

    Science.gov (United States)

    Angell, C. A.; Alba, C.; Arzimanoglou, A.; Fan, J.; Böhmer, R.; Lu, Q.; Sanchez, E.; Senapati, H.; Tatsumisago, M.

    1992-05-01

    We review a variety of measurements on model systems in the medium viscosity range which seem consistent with both thermodynamical (entropy vanishing) and dynamical (mode coupling) origins of glassy behavior and then examine behavior near and below Tg to seek relations between liquid fragility and the non-exponential and non-linear aspects of liquid relaxation processes. We include the model ionic system Ca(NO3)2-KNO3 and analogs, van der Waals systems, and the covalently-bonded system Ge-As-Se in which the relation of liquid properties to the vector percolation concepts of Phillips and Thorpe can be conveniently studied. With some basic phenomenology in the liquid state itself thereby established, we turn attention to longer length-scale processes occurring in viscous liquid media. Among these will be the kinetics of nucleation of crystals, the freezing of microemulsion droplet sizes during continuous cooling of temperature sensitive microemulsions, and the freezing of chemical reactions during continuous cooling or continuous evaporation of solvent. The latter freezings can occur at temperatures which are far above the solvent glass transition temperature depending on solvent fragility, which may be a consideration in the strategies adopted by nature in preservation of plant and insect integrity in cold and arid climates. Finally we consider the slowing down which occurs in liquids with density maxima like water and SiO2 which appear to have, as their low temperature metastable limits, spinodal instabilities (with associated divergences in physical properties) in place of the usual ideal glass transitions. So far little studied for lack of tractable slow systems, these offer a new and challenging arena for relaxation studies.

  8. Liquid Cell Transmission Electron Microscopy

    Science.gov (United States)

    Liao, Hong-Gang; Zheng, Haimei

    2016-05-01

    Liquid cell transmission electron microscopy (TEM) has attracted significant interest in recent years. With nanofabricated liquid cells, it has been possible to image through liquids using TEM with subnanometer resolution, and many previously unseen materials dynamics have been revealed. Liquid cell TEM has been applied to many areas of research, ranging from chemistry to physics, materials science, and biology. So far, topics of study include nanoparticle growth and assembly, electrochemical deposition and lithiation for batteries, tracking and manipulation of nanoparticles, catalysis, and imaging of biological materials. In this article, we first review the development of liquid cell TEM and then highlight progress in various areas of research. In the study of nanoparticle growth, the electron beam can serve both as the illumination source for imaging and as the input energy for reactions. However, many other research topics require the control of electron beam effects to minimize electron beam damage. We discuss efforts to understand electron beam-liquid matter interactions. Finally, we provide a perspective on future challenges and opportunities in liquid cell TEM.

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

    Science.gov (United States)

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

    1990-05-01

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

  10. Studies on Freezing Injury in Plant Cells : II. Protein and Lipid Changes in the Plasma Membranes of Jerusalem Artichoke Tubers during a Lethal Freezing in Vivo.

    Science.gov (United States)

    Uemura, M; Yoshida, S

    1986-01-01

    Plasma membranes were isolated from both unfrozen and frozen tissues of Jerusalem artichoke tubers (Helianthus tuberosus L.) in high purity utilizing an aqueous two-polymer phase partition system. Although the recovery of the plasma membranes was decreased significantly by freezing of tissues even at the nonlethal temperature (-5 degrees C), the isolated plasma membrane samples were considered to be representative of the plasma membranes in situ. Freezing of the tissues at sublethal temperatures resulted in marked changes in the chemical composition of the plasma membrane. Those are losses of sterols and phosphatidylethanolamine from the plasma membranes, and a change of specific proteins with relatively high molecular weights into low molecular weight peptides. These specific proteins were designated as frost susceptible proteins. The properties of the plasma membrane ATPase seem to be not affected so much by the in vivo freezing of cells. However, inhibition of the plasma membrane ATPase by N,N'-dicyclohexylcarbodiimide (DCCD) was relatively low before and after freezing in vivo at the nonlethal temperature at -5 degrees C, but was markedly enhanced by freezing in vivo at sublethal temperatures below -10 degrees C. From the results, it is assumed either that the enzyme molecule was partially modified, especially at the presumed DCCD binding sites or that the DCCD had become more accessible to the enzyme as a result of increased permeability of the plasma membranes. These observed changes are discussed in connection with the mechanism of cell injury. PMID:16664579

  11. Insufficiency of copper ion homeostasis causes freeze-thaw injury of yeast cells as revealed by indirect gene expression analysis.

    Science.gov (United States)

    Takahashi, Shunsuke; Ando, Akira; Takagi, Hiroshi; Shima, Jun

    2009-11-01

    Saccharomyces cerevisiae is exposed to freeze-thaw stress in commercial processes, including frozen dough baking. Cell viability and fermentation activity after a freeze-thaw cycle were dramatically decreased due to freeze-thaw injury. Because this type of injury involves complex phenomena, the injury mechanisms are not fully understood. We examined freeze-thaw injury by indirect gene expression analysis during postthaw incubation after freeze-thaw treatment using DNA microarray profiling. The results showed that genes involved in the homeostasis of metal ions were frequently contained in genes that were upregulated, depending on the freezing period. We assessed the phenotype of deletion mutants of the metal ion homeostasis genes that exhibited freezing period-dependent upregulation and found that the strains with deletion of the MAC1 and CTR1 genes involved in copper ion homeostasis exhibited freeze-thaw sensitivity, suggesting that copper ion homeostasis is required for freeze-thaw tolerance. We found that supplementation with copper ions during postthaw incubation increased intracellular superoxide dismutase activity and intracellular levels of reactive oxygen species were decreased. Moreover, cell viability was increased by supplementation with copper ions. These results suggest that insufficiency of copper ion homeostasis may be one of the causes of freeze-thaw injury. PMID:19749072

  12. Effect of uncontrolled freezing on biological characteristics of human dental pulp stem cells.

    Science.gov (United States)

    Kumar, Ajay; Bhattacharyya, Shalmoli; Rattan, Vidya

    2015-12-01

    Human dental pulp stem cells (hDPSCs) hold great promise as a source of adult stem cells for utilization in regenerative medicine. Successful storage and post thaw recovery of DPSCs without loss of function is a key issue for future clinical application. Most of the cryopreservation methods use controlled rate freezing and vapor phase nitrogen to store stem cells. But these methods are both expensive and laborious. In this study, we isolated DPSCs from a patient undergoing impacted mandibular third molar extraction. We adopted eight different methods of cryopreservation at -80 °C for long term storage of the DPSC aliquots. Various parameters like proliferation, cell death, cell cycle, retention of stemness markers and differentiation potential were studied post cryopreservation period of 1 year. We observed successful recovery of stem cells in every method and a significant difference in proliferation potential and cell death between samples stored by different methods. However, post thaw, all cells retained their stemness markers. All DPSCs stored by different methods were able to differentiate into osteoblast like cells, adipocytes and neural cells. Based on these parameters we concluded that uncontrolled freezing at a temperature of -80 °C is as effective as controlled freezing using ethanol vessels and other cryopreservation methods. To the best of our knowledge, our study provides the first proof of concept that long term storage in uncontrolled freezing of cells at -80 °C in 10 % DMSO does not affect the revival capacity of hDPSCs. This implies that DPSCs may be used successfully for tissue engineering and cell based therapeutics even after long term, uncontrolled cryopreservation.

  13. Freezing tolerance of sea urchin embryonic cells: Differentiation commitment and cytoskeletal disturbances in culture.

    Science.gov (United States)

    Odintsova, Nelly A; Ageenko, Natalya V; Kipryushina, Yulia O; Maiorova, Mariia A; Boroda, Andrey V

    2015-08-01

    This study focuses on the freezing tolerance of sea urchin embryonic cells. To significantly reduce the loss of physiological activity of these cells that occurs after cryopreservation and to study the effects of ultra-low temperatures on sea urchin embryonic cells, we tested the ability of the cells to differentiate into spiculogenic or pigment directions in culture, including an evaluation of the expression of some genes involved in pigment differentiation. A morphological analysis of cytoskeletal disturbances after freezing in a combination of penetrating (dimethyl sulfoxide and ethylene glycol) and non-penetrating (trehalose and polyvinylpyrrolidone) cryoprotectants revealed that the distribution pattern of filamentous actin and tubulin was similar to that in the control cultures. In contrast, very rare spreading cells and a small number of cells with filamentous actin and tubulin were detected after freezing in the presence of only non-penetrating cryoprotectants. The largest number of pigment cells was found in cultures frozen with trehalose or trehalose and dimethyl sulfoxide. The ability to induce the spicule formation was lost in the cells frozen only with non-penetrating cryoprotectants, while it was maximal in cultures frozen in a cryoprotective mixture containing both non-penetrating and penetrating cryoprotectants (particularly, when ethylene glycol was present). Using different markers for cell state assessment, an effective cryopreservation protocol for sea urchin cells was developed: three-step freezing with a low cooling rate (1-2°C/min) and a combination of non-penetrating and penetrating cryoprotectants made it possible to obtain a high level of cell viability (up to 65-80%). PMID:26049089

  14. 3D structures of liquid-phase GaIn alloy embedded in PDMS with freeze casting.

    Science.gov (United States)

    Fassler, Andrew; Majidi, Carmel

    2013-11-21

    Liquid phase electronic circuits are created by freeze casting gallium-indium (GaIn) alloys, such as eutectic gallium-indium (EGaIn), and encapsulating these frozen components within an elastomer. These metal alloys are liquid at room temperature, and can be cast using either injection or a vacuum to fill a PDMS mold and placing the mold in a freezer. Once solidified, a GaIn alloy segment can be manipulated, altered, or bonded to other circuit elements. A stretchable circuit can be fabricated by placing frozen components onto an elastomer substrate, which can be either patterned or flat, and sealing with an additional layer of elastomer. Circuits produced in this fashion are soft, stretchable, and can have complex 3D channel geometries. In contrast, current fabrication techniques, including needle injection, mask deposition, and microcontact printing, are limited to 2D planar designs. Additionally, freeze casting fabrication can create closed loops, multi-terminal circuits with branching features, and large area geometries. PMID:24067934

  15. GMP cryopreservation of large volumes of cells for regenerative medicine: active control of the freezing process.

    Science.gov (United States)

    Massie, Isobel; Selden, Clare; Hodgson, Humphrey; Fuller, Barry; Gibbons, Stephanie; Morris, G John

    2014-09-01

    Cryopreservation protocols are increasingly required in regenerative medicine applications but must deliver functional products at clinical scale and comply with Good Manufacturing Process (GMP). While GMP cryopreservation is achievable on a small scale using a Stirling cryocooler-based controlled rate freezer (CRF) (EF600), successful large-scale GMP cryopreservation is more challenging due to heat transfer issues and control of ice nucleation, both complex events that impact success. We have developed a large-scale cryocooler-based CRF (VIA Freeze) that can process larger volumes and have evaluated it using alginate-encapsulated liver cell (HepG2) spheroids (ELS). It is anticipated that ELS will comprise the cellular component of a bioartificial liver and will be required in volumes of ∼2 L for clinical use. Sample temperatures and Stirling cryocooler power consumption was recorded throughout cooling runs for both small (500 μL) and large (200 mL) volume samples. ELS recoveries were assessed using viability (FDA/PI staining with image analysis), cell number (nuclei count), and function (protein secretion), along with cryoscanning electron microscopy and freeze substitution techniques to identify possible injury mechanisms. Slow cooling profiles were successfully applied to samples in both the EF600 and the VIA Freeze, and a number of cooling and warming profiles were evaluated. An optimized cooling protocol with a nonlinear cooling profile from ice nucleation to -60°C was implemented in both the EF600 and VIA Freeze. In the VIA Freeze the nucleation of ice is detected by the control software, allowing both noninvasive detection of the nucleation event for quality control purposes and the potential to modify the cooling profile following ice nucleation in an active manner. When processing 200 mL of ELS in the VIA Freeze-viabilities at 93.4% ± 7.4%, viable cell numbers at 14.3 ± 1.7 million nuclei/mL alginate, and protein secretion at 10.5 ± 1.7

  16. Resistance to freezing in liquid nitrogen of carnation (Dianthus caryophyllus L. var Eolo) apical and axillary shoot tips excised from different aged in vitro plantlets.

    Science.gov (United States)

    Dereuddre, J; Fabre, J; Bassaglia, C

    1988-05-01

    The ability of shoot tips from carnation (Dianthus caryophyllus L., var. Eolo) cultured in vitro to develop resistance to freezing in liquid nitrogen depends on the physiological state of the cell material and the pretreatment conditions. Regrowth rates close to 100% have been obtained with apical shoot tips isolated from 2 month-old stems, precultured on medium supplemented with sucrose (0.75M) and treated with dimethylsulfoxide (5% or more). Resistance of axillary shoot tips decreased progressively as a funtion of their distance from the apical shoot tip. During the development of the stem from axillary buds (obtained by cutting), progressive increases in the regrowth rate of frozen apices were noted, from 30% before cutting (axillary buds) to 98% after 3 weeks of culture.

  17. Performance and durability of PEM fuel cells operated at sub-freezing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Rangachary [Los Alamos National Laboratory; Davey, John R [Los Alamos National Laboratory; Lujan, Roger W [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory

    2008-01-01

    The durability of polymer electrolyte membrane (PEM) fuel cells operated at sub-freezing temperatures has received increasing attention in recent years. The Department of Energy's PEM fuel cell stack technical targets for the year 2010 include unassisted start-up from -40 {sup o}C and startup from -20 {sup o}C ambient in as low as 30 seconds with < 5 MJ energy consumption. Moreover, the sub-freezing operations should not have any impact on acieving other technical targets including 5000 hours durability. The effect of MEA preparation on the performance of single-PEM fuel cells operated at sub-freezing temperatures is presented. The cell performance and durability are dependent on the MEA and are probably influenced by the porosity of the catalyst layers. When a cell is operated isothermally at -10 {sup o}C in constant current mode, the voltage gradually decreases over time and eventually drops to zero. AC impedance analysis indicated that the rate of voltage loss is initially due to an increase in the charge transfer resistance and is gradual. After a period, the rate of decay accelerates rapidly due to mass transport limitations at the catalyst and/or gas diffusion layers. The high frequency resistance also increases over time during the isothermal operation at sub-freezing temperatures and was a function of the initial membrane water content. LANL prepared MEAs showed very little loss in the catalyst surface area with multiple sub-freezing operations, whereas the commercial MEAs exhibited significant loss in cathode surface area with the anode being unaffected. These results indicate that catalyst layer ice formation is influenced strongly by the MEA and is responsible for the long-term degradation of fuel cells operated at sub-freezing temperatures. This ice formation was monitored using neutron radiography and was found to be concentrated near cell edges at the flow field turns. The water distribution also indicated that ice may be forming mainly in the

  18. Fundamental aspects of the freezing of cells, with emphasis on mammalian ova and embryos

    Energy Technology Data Exchange (ETDEWEB)

    Mazur, P.

    1980-01-01

    The problem in cryobiology is how to cool cells to -196/sup 0/C and return them to normal temperatures without killing them. One important factor is the presence of a protective additive like glycerol or dimethyl sulfoxide. Mammalian cells rarely survive freezing to below -40/sup 0/C in its absence. In the presence of an additive, survival is critically dependent on the cooling rate. Supraoptimal rates and suboptimal rates are both damaging. Death at supraoptimal rates is the result of the formation of intracellular ice and its recrystallization during warming. Death at suboptimal rates is a consequence of the major alterations in aqueous solutions produced by ice formation. The chief effects are a major reduction in the fraction of the solution remaining unfrozen at a given temperature and a major increase in the solute concentration of that fraction. The introduction of molar concentrations of additive greatly reduces both the fraction frozen and the concentration of electrolytes in the unfrozen channels and in the cell interior. Usually, freezing either kills cells outright or it results in survivors that retain full capacity to function. But there is the possibility that in some cases survivors may in fact be impaired genetically or physiologically. All evidence indicates that genetic damage does not occur. But there are clear examples in which freezing does induce nonlethal physiological damage. (ERB)

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

    Energy Technology Data Exchange (ETDEWEB)

    Kandlikar, Satish G. [Rochester Inst. of Technology, Rochester, NY (United States); Lu, Zijie [Rochester Inst. of Technology, Rochester, NY (United States); Rao, Navalgund [Rochester Inst. of Technology, Rochester, NY (United States); Sergi, Jacqueline [Rochester Inst. of Technology, Rochester, NY (United States); Rath, Cody [Rochester Inst. of Technology, Rochester, NY (United States); McDade, Christopher [Rochester Inst. of Technology, Rochester, NY (United States); Trabold, Thomas [General Motors, Honeoye Falls, NY (United States); Owejan, Jon [General Motors, Honeoye Falls, NY (United States); Gagliardo, Jeffrey [General Motors, Honeoye Falls, NY (United States); Allen, Jeffrey [Michigan Technological Univ., Houghton, MI (United States); Yassar, Reza S. [Michigan Technological Univ., Houghton, MI (United States); Medici, Ezequiel [Michigan Technological Univ., Houghton, MI (United States); Herescu, Alexandru [Michigan Technological Univ., Houghton, MI (United States)

    2010-05-30

    In this program, Rochester Institute of Technology (RIT), General Motors (GM) and Michigan Technological University (MTU) have focused on fundamental studies that address water transport, accumulation and mitigation processes in the gas diffusion layer and flow field channels of the bipolar plate. These studies have been conducted with a particular emphasis on understanding the key transport phenomena which control fuel cell operation under freezing conditions.

  20. Quantitative Analysis of Liquid by Quick Freezing Into Ice Using Nd-YAG Laser-Induced Atmospheric Plasma

    Directory of Open Access Journals (Sweden)

    Mohamad Infrawan Yulianto Ichwan

    2005-05-01

    Full Text Available A new approach of quantitative analysis of liquid sample using laser ablation technique was developed. The liquid was immediately freezed using the mixture of dry ice and alcohol in weight ratio of 95% : 5%. As a result, an increase of the repulsion force from the sample surface will enable the generation of the laser-induced shock wave plasma which was difficult to carry out on liquid surface. The ice sample was then irradiated using Nd-YAG laser operated in its fundamental wavelength. In order to increase the signal to background ratio and to obtain a sharp atomic line spectra, helium gas was used instead of air. Dynamic characterization of the spatially integrated time profile of the Cu I 521.8 nm, Cu I 510.5 nm and Ha lines shows a shock excitation stage and cooling stage which is corresponded to our shock wave model even when the plasma was generated under atmospheric gas pressure. Further study of the time profile averaged temperature of the atmospheric plasma also shows an increase of temperature during the shock excitation stage followed by diminution of temperature during the cooling stage. An application of this technique was then applied to quantitative analysis of several liquid samples. A linear calibration curve which intercept at 0 point was obtained for all of the elements investigated in this study such as sodium, potassium, lithium, copper, silver, lead and aluminum. A detection limit of around 1 ppm was found for the above element. This new technique will contribute to a great extent of laser atomic emission spectrochemical analysis for liquid samples.

  1. The effect of magnetic field during freezing and thawing of rat bone marrow-derived mesenchymal stem cells.

    Science.gov (United States)

    Shikata, H; Kaku, M; Kojima, S-I; Sumi, H; Kojima, S-T; Yamamoto, T; Yashima, Y; Kawata, T; Tanne, K; Tanimoto, K

    2016-08-01

    Previous studies showed that a programmed freezer with magnetic field can maintain a high survival rate of mesenchymal stem cells (MSCs). The purpose of this study was to evaluate the influences of magnetic field during freezing and thawing on the survival of MSCs isolated from rat bone marrow. The cells were frozen by a normal programmed freezer or a programmed freezer with magnetic field (CAS-LAB1) and cryopreserved for 7 days at -150 °C. Then, the cells were thawed in the presence or absence of magnetic field. Immediately after thawing, the number of surviving or viable cells was counted. The cell proliferation was examined after 1-week culture. Cryopreserved MSCs which were frozen by a normal freezer or a CAS freezer were transplanted into bone defects artificially made in calvaria of 4-week-old rats. Non-cryopreserved MSCs were used as a control. The rats were sacrificed at 8, 16, or 24 weeks after transplantation and the bone regeneration area was measured. Proliferation rates of MSCs after 1 week were significantly higher in the CAS-freezing-thawing group than in the CAS-freezing group. The extent of new bone formation in the CAS-freezing-thawing group tended to be larger than in CAS-freezing group 24 weeks after transplantation. These results suggest that a magnetic field enhances cell survival during thawing as well as freezing. PMID:27346603

  2. Subcellular imaging of freeze-fractured cell cultures by TOF-SIMS and Laser-SNMS

    Science.gov (United States)

    Fartmann, M.; Dambach, S.; Kriegeskotte, C.; Lipinsky, D.; Wiesmann, H. P.; Wittig, A.; Sauerwein, W.; Arlinghaus, H. F.

    2003-01-01

    We have examined atomic and molecular distributions in freeze-fractured freeze-dried primary osteoblasts and cancer cells using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and non-resonant laser secondary neutral mass spectrometry (NR-Laser-SNMS). A pulsed Ga primary ion beam with a diameter of approximately 200 nm was employed to bombard the sample. Ion-induced electron-images were used to identify individual cells. High resolution elemental and molecular images were obtained from cell cultures. From these data the K/Na ratio was determined. It shows a higher K-concentration inside individual cells demonstrating that the chemical and structural integrity of living cells were preserved by the applied preparation technique. Consecutive presputtering of the sample with different primary ion dose densities was used to move the analysis plane toward the inside of the cell. It can be concluded that TOF-SIMS and Laser-SNMS are well suited for imaging trace element and molecule concentrations in biological samples.

  3. The effect of freeze-thaw cycles on gene expression levels in lymphoblastoid cell lines.

    Directory of Open Access Journals (Sweden)

    Minal Çalışkan

    Full Text Available Epstein-Barr virus (EBV transformed lymphoblastoid cell lines (LCLs are a widely used renewable resource for functional genomic studies in humans. The ability to accumulate multidimensional data pertaining to the same individual cell lines, from complete genomic sequences to detailed gene regulatory profiles, further enhances the utility of LCLs as a model system. However, the extent to which LCLs are a faithful model system is relatively unknown. We have previously shown that gene expression profiles of newly established LCLs maintain a strong individual component. Here, we extend our study to investigate the effect of freeze-thaw cycles on gene expression patterns in mature LCLs, especially in the context of inter-individual variation in gene expression. We report a profound difference in the gene expression profiles of newly established and mature LCLs. Once newly established LCLs undergo a freeze-thaw cycle, the individual specific gene expression signatures become much less pronounced as the gene expression levels in LCLs from different individuals converge to a more uniform profile, which reflects a mature transformed B cell phenotype. We found that previously identified eQTLs are enriched among the relatively few genes whose regulations in mature LCLs maintain marked individual signatures. We thus conclude that while insight drawn from gene regulatory studies in mature LCLs may generally not be affected by the artificial nature of the LCL model system, many aspects of primary B cell biology cannot be observed and studied in mature LCL cultures.

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

    Science.gov (United States)

    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.

  5. Relation between transport and thermodynamic properties in liquid sp-electron metals near freezing.

    Science.gov (United States)

    Alonso, J A; March, N H

    1999-10-01

    Classical statistical mechanics based on assumed pair potentials leads, for liquid metals, to an approximate relation between shear viscosity eta, surface tension sigma, and thermal velocity vT defined as (kBT/M)(1/2), with M the ionic mass. Theory predicts for the dimensionless grouping sigma/etav(T) evaluated at the melting temperature Tm a single value 15 / 16; liquid sp-electron metals exhibit, however, a scatter from around 0.7 to 2.3. Therefore, an alternative grouping sigma/etav(s), with v(s) the velocity of sound, is considered here in detail, first using experimental data and second using both theoretical and semiempirical arguments. The scatter of sigma/etav(s) at Tm is less than for the earlier grouping, and also insight can be gained as to various physical factors determining sigma/etav(s). In essence, this quantity is proportional to the product of two factors, both dimensionless, namely, the surface thickness L measured in units of the mean interionic separation, and the square root of the energy Mv(2)s, measured in units of the thermal energy kBTm. Theoretical estimates are made of both of these factors, in fair accord with the experimental data. PMID:11970248

  6. A freeze-dried graphene counter electrode enhances the performance of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Kai-Hsiang; Wang, Hong-Wen, E-mail: hongwen@cycu.edu.tw

    2014-01-01

    A flexible graphene/polyimide (PI) counter electrode without a fluorine-doped tin oxide (FTO) layer has been fabricated for dye-sensitized solar cell (DSSCs) applications. The flexible counter electrode consists of polyimide double-sided tape as a substrate beneath a graphene film acting as the conductive and catalytic layer. Chemically reduced graphene oxide (rGO) on the PI electrode (rGO-PI) shows comparable catalytic activity to that of the reference sputtered platinum/FTO counter electrodes (Sputter-Pt/FTO). A DSSC with a freeze-dried rGO-PI (FD-rGO-PI) counter electrode shows an overall conversion efficiency (η) of 5.45%, while that of the conventional Sputter-Pt/FTO electrode is 5.52%. The DSSC with a thermally dried rGO-PI (Gel-rGO-PI) counter electrode (not freeze-dried) exhibits a smooth morphology and much poorer performance (η = 1.61%). Field emission scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry measurements demonstrate that the FD-rGO-PI electrode possesses a porous structure, numerous edges, minimum charge-transfer resistance and a higher electrocatalytic activity toward the I{sub 3}{sup −}/I{sup −} redox couple than that of the Gel-rGO-PI electrode. The high electrocatalytic activity, facile preparation procedure, absence of FTO, and material flexibility render the FD-rGO-PI electrode an ideal alternative to conventional DSSC counter electrodes. - Highlights: • Highly rough and conductive graphene-based counter electrode is synthesized. • The characteristics of graphene surface by freeze drying are different. • The graphene counter electrode exhibits comparable performance to that of sputtered Pt one.

  7. Meat Freezing Theories and Novel Freezing Technologies%肉类冷冻理论与冷冻新技术

    Institute of Scientific and Technical Information of China (English)

    金文刚

    2008-01-01

    Main meat freezing theories,including transition theory,glass transformation theory and ice crystallization theory,were introduced.Some novel freezing technologies such as high pressure freezing,ultrasonic freezing,ice nucleus bacteria freezing protein,cell alive system freezing and decompression freezing were also generally reviewed.

  8. Comparison of the pharmacokinetics, safety and tolerability of two concentrations of a new liquid recombinant human growth hormone formulation versus the freeze-dried formulation

    OpenAIRE

    Liedert, Bernd; Forssmann, Ulf; Wolna, Peter; Golob, Michaela; Kovar, Andreas

    2010-01-01

    Background Somatropin is recombinant human growth hormone (GH) used for the treatment of growth failure in children and GH deficiency in adults. Two concentrations of a liquid formulation have been developed: 5.83 and 8.0 mg/mL. This trial compared the pharmacokinetics (PK), safety and tolerability of these two liquid concentrations against the freeze-dried (FD) formulation in healthy volunteers. Methods In an open-label, single-centre, three-way crossover study, volunteers (aged 18-45 years)...

  9. Neutron Computed Tomography of Freeze/thaw Phenomena in Polymer Electrolyte Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Matthew M. Mech; Jack Brenizer; Kenan Unlu; A.K. Heller

    2008-12-12

    This report summarizes the final year's progress of the three-year NEER program. The overall objectives of this program were to 1) design and construct a sophisticated hight-resolution neutron computed tomography (NCT) facility, 2) develop novel and sophisticated liquid water and ice quantification analysis software for computed tomography, and 3) apply the advanced software and NCT capability to study liquid and ice distribution in polymer electrolyte fuel cells (PEFCs) under cold-start conditions. These objectives have been accomplished by the research team, enabling a new capability for advanced 3D image quantification with neutron imaging for fuel cell and other applications. The NCT water quantification methodology and software will greatly add to the capabilities of the neutron imaging community, and the quantified liquid water and ice distribution provided by its application to PEFCs will enhance understanding and guide design in the fuel cell community.

  10. The effect of initial tonicity on freeze/thaw injury to human red cells suspended in solutions of sodium chloride.

    Science.gov (United States)

    Pegg, D E; Diaper, M P

    1991-02-01

    Human red blood cells, suspended in solutions of sodium chloride, have been frozen to temperatures between -2 and -14 degrees C and thawed, and the extent of hemolysis was measured. In parallel experiments, red cells were exposed to similar cycles of change in the composition of the suspending solution, but by dialysis at 21 degrees C. The tonicity of the saline in which the cells were initially suspended was varied between 0.6x isotonic and 4x isotonic; some samples from each experimental treatment were returned to isotonic saline before hemolysis was measured. It was found that the tonicity of the saline used to suspend the cells for the main body of the experiment affected the amount of hemolysis measured: raising the tonicity from 0.6x to 1x to 2x reduced hemolysis, both in the freezing and in the dialysis experiments, whereas raising the tonicity further to 4x reversed that trend. There was little difference between the freeze/thaw and the dialysis treatments for the cells suspended in 1x or 2x saline, whether or not the cells were returned to isotonic conditions. However, the cells suspended in 0.6x saline showed greater damage from freezing and thawing than from the comparable change in the composition of the solution, whether or not they were returned to isotonic conditions. Cells that were suspended in 4x saline and exposed to changes in salt concentration by dialysis showed less hemolysis when they were assayed in the 4x solution than cells that had received the comparable freezing/thaw treatment, but when the experiment included a return to isotonicity, the two treatments gave similar results. Returning the cells to isotonic saline had a negligible affect on the cells in 0.6x and 1x saline, but caused considerable hemolysis in the 2x and 4x samples, more so after dialysis than after freezing and thawing. We conclude that cells suspended in 0.6x and 4x saline behave differently from cells suspended in 1x and 2x saline and hence that cells suspended in a

  11. Air-Cooled Stack Freeze Tolerance Freeze Failure Modes and Freeze Tolerance Strategies for GenDriveTM Material Handling Application Systems and Stacks Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, David, W.

    2012-02-14

    Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below freezing, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was freeze tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology for air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve freeze tolerance and mitigate freeze-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. Freeze tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack freeze tolerance. At this time, the most cost effective solutions are at the system level. The freeze mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.

  12. Biotransport and intracellular ice formation phenomena in freezing human embryonic kidney cells (HEK293T).

    Science.gov (United States)

    Xu, Yunpeng; Zhao, Gang; Zhou, Xiaoming; Ding, Weiping; Shu, Zhiquan; Gao, Dayong

    2014-04-01

    The objective of this study is to determine the cryobiological characteristics of human embryonic kidney (HEK293T) cells. The cell membrane hydraulic conductivity (L(pg)) and the activation energy of water transport (E(Lp)) were determined in the absence/presence of cryoprotectant agent (CPA), while the nucleation rate kinetic and thermodynamic parameters (Ωo(SCN) and κo(SCN)) were determined in the absence of CPA. Since dehydration and intracellular ice formation (IIF) are two factors that may cause damage to cells during the freezing process, systematical freezing experiments were carried out at different cooling rates (5, 10, 15, 20, 30, and 60°C/min) under the commercial available cryomicroscopy (FDCS 196, Linkham, Waterfield, UK) to further explore the cryoinjury mechanism for HEK293T cells. By simultaneously fitting the water transport equation to the experimentally measured volumetric shrinkage data at 5, 10, and 15°C/min, the "combined best fit" membrane permeability parameters for HEK293T cells in both phosphate buffer saline (PBS) and CPA media (0.75M Me2SO in PBS) are determined. They are L(pg)=2.85×10(-14)m/s/Pa (0.17μm/min/atm), E(Lp)=142.91kJ/mol (34.13kcal/mol) (R(2)=0.990), and L(pg)[cpa]=2.73±0.44×10(-14)m/s/Pa (0.16±0.03μm/min/atm), E(Lp)[cpa]=152.52±27.69kJ/mol (36.42±6.61kcal/mol) (R(2)=0.993), respectively. An optimal cooling rate B(opt) (the highest cooling rate without IIF) was determined to be 14.24°C/min in the absence of CPA. Additionally, the ice nucleation parameters (Ωo(SCN) and κo(SCN)) were averaged to be 1.31±0.11×10(8)m(-2)s(-1) and 7.67±2.55×10(9)K(5) for the cooling rates 20, 30, and 60°C/min. PMID:24582893

  13. Behavioral profile and dorsal hippocampal cells in carioca high-conditioned freezing rats.

    Science.gov (United States)

    Dias, Gisele Pereira; Bevilaqua, Mário Cesar do Nascimento; Silveira, Anna Claudia Domingos; Landeira-Fernandez, Jesus; Gardino, Patrícia Franca

    2009-12-28

    Selection for contextual fear conditioning is an important behavioral paradigm for studying the role of genetic variables and their interaction with the surrounding environment in the etiology and development of anxiety disorders. Recently, a new line of animals selectively bred for high levels of freezing in response to contextual cues previously associated with footshock was developed from a Wistar population. The purpose of the present study was to evaluate the emotional and cognitive aspects of this new line of animals, which has been named Carioca High-Freezing (CHF). For the characterization of anxious behavior, CHF and control animals were tested in the elevated plus-maze (EPM) and the social interaction test. CHF animals were significantly more anxious than control rats in terms of both the number of entries into EPM open arms and the percentage of time spent in these arms. The time spent in social interaction behavior was also significantly decreased. No statistical differences were found in locomotor activity, as measured by both the number of entries into the closed arms of the EPM and the number of crossings into the social interaction test arena. No differences between CHF and control groups were found in the depression forced swimming test, suggesting that the anxiety trait selected in the CHF line did not interact with affective disorders traits such as those for depression. Cognitive aspects of the CHF rats were evaluated in the object recognition task. Results from this test indicated no difference between the two groups. The present study also encompassed histological analysis of the dorsal hippocampus from CHF and control animals. Results revealed an absence of qualitative and quantitative differences between these two groups of animals in cells located in the dentate gyrus, CA1, and CA3 areas. Therefore, future studies are required to further investigate the possible neural mechanisms involved in the origin and development of the anxious

  14. Incorporation of [14C]-palmitate into lipids of Brassica cells during the induction of freezing tolerance

    International Nuclear Information System (INIS)

    Changes in plasma membrane lipid composition have been causally related to increased freezing tolerance. Studies of lipid metabolism during ABA induction of freezing tolerance in Brassica napus suspension cultures were undertaken. Cells were labeled with [14C]-palmitate four days after transfer to fresh medium (control) or medium containing ABA (which increases freezing tolerance). At times between one and 20 hrs after labeling, ABA-treated cells incorporated almost twice the amount of label as controls cells. Approximately 80% of the radioactivity was associated with neutral lipids in ABA-treated cells and controls. Incorporation of label into total cellular polar lipids was 4.9 x 105 dpm/mg protein for control cells and 1 x 106 dpm/mg protein for cells transferred to medium containing ABA. Analysis of lipids following alkaline hydrolysis indicated that incorporation of [14C]-palmitate into glucosylceramide of ABA-treated cells was less than 60% of control values when expressed relative to that of the total polar lipids. Incorporation into ceramides was also depressed in ABA-treated cells

  15. Ice formation in PEM fuel cells operated isothermally at sub-freezing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Rangachary [Los Alamos National Laboratory; Luhan, Roger W [Los Alamos National Laboratory; Davey, John R [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Hussey, Daniel S [NIST; Jacobson, David L [NIST; Arif, Muhammad [NIST

    2009-01-01

    The effect of MEA and GDL structure and composition on the performance of single-PEM fuel cells operated isothermally at subfreezing temperatures is presented. The cell performance and durability are not only dependent on the MEA/GDL materials used but also on their interfaces. When a cell is operated isothermally at sub-freezing temperatures in constant current mode, the water formation due to the current density initially hydrates the membrane/ionomer and then forms ice in the catalyst layer/GDL. An increase in high frequency resistance was also observed in certain MEAs where there is a possibility of ice formation between the catalyst layer and GDL leading to a loss in contact area. The total water/ice holding capacity for any MEA was lower at lower temperatures and higher current densities. The durability of MEAs subjected to multiple isothermal starts was better for LANL prepared MEAs as compared to commercial MEAs, and cloth GDLs when compared to paper GDLs. The ice formation was monitored using high-resolution neutron radiography and was found to be concentrated near the cathode catalyst layer. However, there was significant ice formation in the GDLs especially at the higher temperature ({approx} -10 C) and lower current density (0.02 A/cm{sup 2}) operations. These results are consistent with the longer-term durability observations that show more severe degradation at the lower temperatures.

  16. Small molecule ice recrystallization inhibitors enable freezing of human red blood cells with reduced glycerol concentrations.

    Science.gov (United States)

    Capicciotti, Chantelle J; Kurach, Jayme D R; Turner, Tracey R; Mancini, Ross S; Acker, Jason P; Ben, Robert N

    2015-01-01

    In North America, red blood cells (RBCs) are cryopreserved in a clinical setting using high glycerol concentrations (40% w/v) with slow cooling rates (~1°C/min) prior to storage at -80°C, while European protocols use reduced glycerol concentrations with rapid freezing rates. After thawing and prior to transfusion, glycerol must be removed to avoid intravascular hemolysis. This is a time consuming process requiring specialized equipment. Small molecule ice recrystallization inhibitors (IRIs) such as β-PMP-Glc and β-pBrPh-Glc have the ability to prevent ice recrystallization, a process that contributes to cellular injury and decreased cell viability after cryopreservation. Herein, we report that addition of 110 mM β-PMP-Glc or 30 mM β-pBrPh-Glc to a 15% glycerol solution increases post-thaw RBC integrity by 30-50% using slow cooling rates and emphasize the potential of small molecule IRIs for the preservation of cells.

  17. A Simple and Efficient Method of Slow Freezing for Human Embryonic Stem Cells and Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Imaizumi, Keitaro; Iha, Momoe; Nishishita, Naoki; Kawamata, Shin; Nishikawa, Shinichi; Akuta, Teruo

    2016-01-01

    Protocols available for the cryopreservation of human embryonic stem (ES) and induced pluripotent stem (iPS) cells are very inefficient and laborious compared to those for the cryopreservation of murine ES/iPS cells or other general cell lines. While the vitrification method may be adequate when working with small numbers of human ES/iPS cells, it requires special skills and is unsuitable when working with large cell numbers. Here, we describe a simple and efficient method for the cryopreservation of hES/hiPS cells that is based on a conventional slow freezing method that uses a combination of Pronase/EDTA for Stem™ and CP-5E™ [final concentrations: 6 % hydroxyethyl starch, 5 % DMSO, and 5 % ethylene glycol in saline]. CP-5E™ is highly effective for the cryopreservation of small cell clumps produced by hES/hiPS colony detachment in the presence of Pronase and EDTA (Pronase/EDTA for Stem™, a formulation containing multiple digestive enzymes from Streptomyces griseus). This novel method would be quite useful for large-scale hES/iPS cell banking for use in clinical applications.

  18. 液氮冻结应用于冰淇淋工业化生产%Industrial Application of Liquid Nitrogen Freezing Technology in Production of Ice Cream

    Institute of Scientific and Technical Information of China (English)

    余保宁

    2011-01-01

    论文阐述了传统冰淇淋生产中存在的问题和可用于冰淇淋工业化生产的液氮快速冻结设备.分析了液氮冻结技术及其设备结构,液氮冻结在冰淇淋生产中体现的优越性.通过开发液氮冻结设备和技术,使液氮应用于冰淇淋工业化生产成为现实,从而提高冰淇淋产品质量和生产效率,降低生产过程的能耗及成本,并有助于生态环保.%The paper discussed the problems in traditional manufacture and production of ice cream. Liquid nitrogen freezing technology was then introduced, including the equipments and the advantage of this technology in ice cream production. Developments in the technology and equipments of liquid nitrogen freezing make it possible to use liquid nitrogen in the industrial production of ice cream. It can improve the quality of ice cream products, enhance the productivity, reduce the productive energy consumption and benefit to environmental protection.

  19. Liquid Crystal Cells Based on Photovoltaic Substrates

    Science.gov (United States)

    Lucchetti, L.; Kushnir, K.; Zaltron, A.; Simoni, F.

    2016-02-01

    Liquid crystal cells with LiNbO3:Fe crystals as substrates, are described. The photovoltaic field generated by the substrates is able to reorient the liquid crystal director thus giving rise to a phase shift on the light propagating through the cell, as in liquid crystal light valves. The process does not require the application of an external electric field, thus being potentially useful for applications requiring a high degree of compactness. An efficient optical switch with a high transmission contrast, based on the described optically-induced electric field, is also proposed.

  20. Pore architecture and cell viability on freeze dried 3D recombinant human collagen-peptide (RHC)–chitosan scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing; Zhou, Aimei; Deng, Aipeng [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Yang [Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Gao, Lihu; Zhong, Zhaocai [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Shulin, E-mail: yshulin@njust.edu.cn [School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2015-04-01

    Pore architecture of 3D scaffolds used in tissue engineering plays a critical role in the maintenance of cell survival, proliferation and further promotion of tissue regeneration. We investigated the pore size and structure, porosity, swelling as well as cell viability of a series of recombinant human collagen-peptide–chitosan (RHCC) scaffolds fabricated by lyophilization. In this paper, freezing regime containing a final temperature of freezing (T{sub f}) and cooling rates was applied to obtain scaffolds with pore size ranging from 100 μm to 120 μm. Other protocols of RHC/chitosan suspension concentration and ratio modification were studied to produce more homogenous and appropriate structural scaffolds. The mean pore size decreased along with the decline of T{sub f} at a slow cooling rate of 0.7 °C/min; a more rapid cooling rate under 5 °C/min resulted to a smaller pore size and more homogenous microstructure. High concentration could reduce pore size and lead to thick well of scaffold, while improved the ratio of RHC, lamellar and fiber structure coexisted with cellular pores. Human umbilical vein endothelial cells (HUVECs) were seeded on these manufactured scaffolds, the cell viability represented a negative correlation to the pore size. This study provides an alternative method to fabricate 3D RHC–chitosan scaffolds with appropriate pores for potential tissue engineering. - Highlights: • Fabrication of recombinant human collagen-chitosan scaffolds by freezing drying • Influence of freeze drying protocols on lyophilized scaffolds • Pore size, microstructure, porosity, swelling and cell viability were compared. • The optimized porous scaffold is suitable for cell (HUVEC) seeding.

  1. Pore architecture and cell viability on freeze dried 3D recombinant human collagen-peptide (RHC)–chitosan scaffolds

    International Nuclear Information System (INIS)

    Pore architecture of 3D scaffolds used in tissue engineering plays a critical role in the maintenance of cell survival, proliferation and further promotion of tissue regeneration. We investigated the pore size and structure, porosity, swelling as well as cell viability of a series of recombinant human collagen-peptide–chitosan (RHCC) scaffolds fabricated by lyophilization. In this paper, freezing regime containing a final temperature of freezing (Tf) and cooling rates was applied to obtain scaffolds with pore size ranging from 100 μm to 120 μm. Other protocols of RHC/chitosan suspension concentration and ratio modification were studied to produce more homogenous and appropriate structural scaffolds. The mean pore size decreased along with the decline of Tf at a slow cooling rate of 0.7 °C/min; a more rapid cooling rate under 5 °C/min resulted to a smaller pore size and more homogenous microstructure. High concentration could reduce pore size and lead to thick well of scaffold, while improved the ratio of RHC, lamellar and fiber structure coexisted with cellular pores. Human umbilical vein endothelial cells (HUVECs) were seeded on these manufactured scaffolds, the cell viability represented a negative correlation to the pore size. This study provides an alternative method to fabricate 3D RHC–chitosan scaffolds with appropriate pores for potential tissue engineering. - Highlights: • Fabrication of recombinant human collagen-chitosan scaffolds by freezing drying • Influence of freeze drying protocols on lyophilized scaffolds • Pore size, microstructure, porosity, swelling and cell viability were compared. • The optimized porous scaffold is suitable for cell (HUVEC) seeding

  2. Small molecule ice recrystallization inhibitors mitigate red blood cell lysis during freezing, transient warming and thawing

    Science.gov (United States)

    Briard, Jennie G.; Poisson, Jessica S.; Turner, Tracey R.; Capicciotti, Chantelle J.; Acker, Jason P.; Ben, Robert N.

    2016-03-01

    During cryopreservation, ice recrystallization is a major cause of cellular damage. Conventional cryoprotectants such as dimethyl sulfoxide (DMSO) and glycerol function by a number of different mechanisms but do not mitigate or control ice recrystallization at concentrations utilized in cryopreservation procedures. In North America, cryopreservation of human red blood cells (RBCs) utilizes high concentrations of glycerol. RBC units frozen under these conditions must be subjected to a time-consuming deglycerolization process after thawing in order to remove the glycerol to <1% prior to transfusion thus limiting the use of frozen RBC units in emergency situations. We have identified several low molecular mass ice recrystallization inhibitors (IRIs) that are effective cryoprotectants for human RBCs, resulting in 70–80% intact RBCs using only 15% glycerol and slow freezing rates. These compounds are capable of reducing the average ice crystal size of extracellular ice relative to a 15% glycerol control validating the positive correlation between a reduction in ice crystal size and increased post-thaw recovery of RBCs. The most potent IRI from this study is also capable of protecting frozen RBCs against the large temperature fluctuations associated with transient warming.

  3. Small molecule ice recrystallization inhibitors mitigate red blood cell lysis during freezing, transient warming and thawing.

    Science.gov (United States)

    Briard, Jennie G; Poisson, Jessica S; Turner, Tracey R; Capicciotti, Chantelle J; Acker, Jason P; Ben, Robert N

    2016-01-01

    During cryopreservation, ice recrystallization is a major cause of cellular damage. Conventional cryoprotectants such as dimethyl sulfoxide (DMSO) and glycerol function by a number of different mechanisms but do not mitigate or control ice recrystallization at concentrations utilized in cryopreservation procedures. In North America, cryopreservation of human red blood cells (RBCs) utilizes high concentrations of glycerol. RBC units frozen under these conditions must be subjected to a time-consuming deglycerolization process after thawing in order to remove the glycerol to recrystallization inhibitors (IRIs) that are effective cryoprotectants for human RBCs, resulting in 70-80% intact RBCs using only 15% glycerol and slow freezing rates. These compounds are capable of reducing the average ice crystal size of extracellular ice relative to a 15% glycerol control validating the positive correlation between a reduction in ice crystal size and increased post-thaw recovery of RBCs. The most potent IRI from this study is also capable of protecting frozen RBCs against the large temperature fluctuations associated with transient warming.

  4. A freeze-fracture study on the developing satellite cells of spinal ganglia in the chick embryo

    Directory of Open Access Journals (Sweden)

    Claudio A. Ferraz de Carvalho

    1988-03-01

    Full Text Available A freeze-fracture analysis of the satellite cells of spinal ganglia of the chick embryo was performed in 8 successive stages of development, from the 5th incubation day to hatching. The characteristic laminar disposition of the cells were first observed on the 7th day. Tight junctions were found at the 20th incubation day. Small groups or irregular aggregates of particles, but not gap junctions, were described on the 7th and 8th days. Pinocytotic vesicles were pointed out in the different stages considered.

  5. Freezing avoidance by supercooling in Olea europaea cultivars: the role of apoplastic water, solute content and cell wall rigidity.

    Science.gov (United States)

    Arias, Nadia S; Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo

    2015-10-01

    Plants can avoid freezing damage by preventing extracellular ice formation below the equilibrium freezing temperature (supercooling). We used Olea europaea cultivars to assess which traits contribute to avoid ice nucleation at sub-zero temperatures. Seasonal leaf water relations, non-structural carbohydrates, nitrogen and tissue damage and ice nucleation temperatures in different plant parts were determined in five cultivars growing in the Patagonian cold desert. Ice seeding in roots occurred at higher temperatures than in stems and leaves. Leaves of cold acclimated cultivars supercooled down to -13 °C, substantially lower than the minimum air temperatures observed in the study site. During winter, leaf ice nucleation and leaf freezing damage (LT50 ) occurred at similar temperatures, typical of plant tissues that supercool. Higher leaf density and cell wall rigidity were observed during winter, consistent with a substantial acclimation to sub-zero temperatures. Larger supercooling capacity and lower LT50 were observed in cold-acclimated cultivars with higher osmotically active solute content, higher tissue elastic adjustments and lower apoplastic water. Irreversible leaf damage was only observed in laboratory experiments at very low temperatures, but not in the field. A comparative analysis of closely related plants avoids phylogenetic independence bias in a comparative study of adaptations to survive low temperatures. PMID:25737264

  6. Freezing avoidance by supercooling in Olea europaea cultivars: the role of apoplastic water, solute content and cell wall rigidity.

    Science.gov (United States)

    Arias, Nadia S; Bucci, Sandra J; Scholz, Fabian G; Goldstein, Guillermo

    2015-10-01

    Plants can avoid freezing damage by preventing extracellular ice formation below the equilibrium freezing temperature (supercooling). We used Olea europaea cultivars to assess which traits contribute to avoid ice nucleation at sub-zero temperatures. Seasonal leaf water relations, non-structural carbohydrates, nitrogen and tissue damage and ice nucleation temperatures in different plant parts were determined in five cultivars growing in the Patagonian cold desert. Ice seeding in roots occurred at higher temperatures than in stems and leaves. Leaves of cold acclimated cultivars supercooled down to -13 °C, substantially lower than the minimum air temperatures observed in the study site. During winter, leaf ice nucleation and leaf freezing damage (LT50 ) occurred at similar temperatures, typical of plant tissues that supercool. Higher leaf density and cell wall rigidity were observed during winter, consistent with a substantial acclimation to sub-zero temperatures. Larger supercooling capacity and lower LT50 were observed in cold-acclimated cultivars with higher osmotically active solute content, higher tissue elastic adjustments and lower apoplastic water. Irreversible leaf damage was only observed in laboratory experiments at very low temperatures, but not in the field. A comparative analysis of closely related plants avoids phylogenetic independence bias in a comparative study of adaptations to survive low temperatures.

  7. Role of intracellular freezing in the death of cells cooled at supraoptimal rates. [Preservation of erythrocytes, bone marrow cells, and yeasts by freezing

    Energy Technology Data Exchange (ETDEWEB)

    Mazur, P.

    1976-01-01

    Cooling velocity is one of the major factors that determines whether viable cells can be frozen to temperatures that permit indefinite storage. Cooling either too slowly or too rapidly tends to be damaging. Optimum cooling rates are reported for mouse marrow stem cells, yeast, and human red cells.

  8. A study on ice crystal formation behavior at intracellular freezing of plant cells using a high-speed camera.

    Science.gov (United States)

    Ninagawa, Takako; Eguchi, Akemi; Kawamura, Yukio; Konishi, Tadashi; Narumi, Akira

    2016-08-01

    Intracellular ice crystal formation (IIF) causes several problems to cryopreservation, and it is the key to developing improved cryopreservation techniques that can ensure the long-term preservation of living tissues. Therefore, the ability to capture clear intracellular freezing images is important for understanding both the occurrence and the IIF behavior. The authors developed a new cryomicroscopic system that was equipped with a high-speed camera for this study and successfully used this to capture clearer images of the IIF process in the epidermal tissues of strawberry geranium (Saxifraga stolonifera Curtis) leaves. This system was then used to examine patterns in the location and formation of intracellular ice crystals and to evaluate the degree of cell deformation because of ice crystals inside the cell and the growing rate and grain size of intracellular ice crystals at various cooling rates. The results showed that an increase in cooling rate influenced the formation pattern of intracellular ice crystals but had less of an effect on their location. Moreover, it reduced the degree of supercooling at the onset of intracellular freezing and the degree of cell deformation; the characteristic grain size of intracellular ice crystals was also reduced, but the growing rate of intracellular ice crystals was increased. Thus, the high-speed camera images could expose these changes in IIF behaviors with an increase in the cooling rate, and these are believed to have been caused by an increase in the degree of supercooling.

  9. A sliding cell technique for diffusion measurements in liquid metals

    OpenAIRE

    Yongliang Geng; Chunao Zhu; Bo Zhang

    2014-01-01

    The long capillary and shear cell techniques are the usual methods for diffusion measurements in liquid metals. Here we present a new “sliding cell technique” to measure interdiffusion in liquid alloys, which combines the merits of these two methods. Instead of a number of shear cells, as used in the shear cell method, only one sliding cell is designed to separate and join the liquid diffusion samples. Using the sliding cell technique, the influence of the heating process (which affects liqui...

  10. Polymer's anchoring behavior in liquid crystal cells

    Science.gov (United States)

    Cui, Yue

    The current dissertation mainly discusses about the polymers anchoring behavior in liquid crystal cells in two aspects: surface interaction and bulk interaction. The goal of the research is to understand the fundamental physics of anchoring strength and apply the knowledge to liquid crystal display devices. Researchers proposed two main contributors to the surface anchoring strength: the micro grooves generated by external force and the polymer chain's alignment. Both of them has experimental proofs. In the current study, explorations were made to understand the mechanisms of surface anchoring strength and easy axis of surface liquid crystal provided by rubbed polymer alignment layer. The work includes not only the variation of the alignment layer itself such as thickness(Chapter 3) and polymer side chain (Chapter 5), but also the variation of external conditions such as temperature (Chapter 4) and rubbing condition (Chapter 6). To determine the polar and azimuthal anchoring strengths, Rapini-Papoular's expression was applied. However, it was discovered that higher order terms may be required in order to fit the experimental result or theoretically predict unique anchoring behaviors (Chapter 2, Chapter 6). SEM and AFM technologies were introduced to gather the actual structures of polymer alignment layer and extrapolate the alignment of liquid crystal in a micro scale. The result shows that the anchoring strength can be adjusted by the layer thickness, side chain structure, while the easy axis direction can be adjusted by a second rubbing direction. In addition, different anchoring conditions combined with liquid crystal's elastic energy can generate quite different forms of liquid crystals (Chapter 7). In the study of bulk alignment, the main contrition from the current dissertation is applying the understanding of anchoring behavior to optimizing actual switchable devices. Conventional PDLC performance can be tuned with the knowledge of the polymer and the liquid

  11. Two-Step Freezing in Alkane Monolayers on Colloidal Silica Nanoparticles: From a Stretched-Liquid to an Interface-Frozen State.

    Science.gov (United States)

    Gao, Xia; Huber, Patrick; Su, Yunlan; Zhao, Weiwei; Wang, Dujin

    2016-08-01

    The crystallization behavior of an archetypical soft/hard hybrid nanocomposite, that is, an n-octadecane C18/SiO2-nanoparticle composite, was investigated by a combination of differential scanning calorimetry (DSC) and variable-temperature solid-state (13)C nuclear magnetic resonance (VT solid-state (13)C NMR) as a function of silica nanoparticles loading. Two latent heat peaks prior to bulk freezing, observed for composites with high silica loading, indicate that a sizable fraction of C18 molecules involve two phase transitions unknown from the bulk C18. Combined with the NMR measurements as well as experiments on alkanes and alkanols at planar amorphous silica surfaces reported in the literature, this phase behavior can be attributed to a transition toward a 2D liquid-like monolayer and subsequently a disorder-to-order transition upon cooling. The second transition results in the formation of a interface-frozen monolayer of alkane molecules with their molecular long axis parallel to the nanoparticles' surface normal. Upon heating, the inverse phase sequence was observed, however, with a sizable thermal hysteresis in accord with the characteristics of the first-order phase transition. A thermodynamic model considering a balance of interfacial bonding, chain stretching elasticity, and entropic effects quantitatively accounts for the observed behavior. Complementary synchrotron-based wide-angle X-ray diffraction (WAXD) experiments allow us to document the strong influence of this peculiar interfacial freezing behavior on the surrounding alkane melts and in particular the nucleation of a rotator phase absent in the bulk C18. PMID:27386888

  12. Deficiency in the glycerol channel Fps1p confers increased freeze tolerance to yeast cells: application of the fps1delta mutant to frozen dough technology.

    Science.gov (United States)

    Izawa, Shingo; Ikeda, Kayo; Maeta, Kazuhiro; Inoue, Yoshiharu

    2004-12-01

    Intracellular glycerol content affects the freeze-thaw stress tolerance of Saccharomyces cerevisiae. We have recently reported that intracellular-glycerol-enriched cells cultured in glycerol medium acquire tolerance to freeze stress and retain high leavening ability even in dough after frozen storage [Izawa et al. (2004) Appl Microbiol Biotechnol http://dx.doi.org/10.1007/s00253-004-1624-4]. A deletion mutant of the FPS1 gene, which encodes a glycerol channel, accumulates glycerol inside the cell without an exogenous supply of glycerol into the medium. We found that the fps1delta cells acquired tolerance to freeze stress and retained high leavening ability in dough after frozen storage for 7 days. These results suggest that the fps1delta mutant is a useful strain for developing better frozen-dough with a commercial advantage. PMID:15278313

  13. Freezing of Fresh Wharton's Jelly From Human Umbilical Cords Yields High Post-Thaw Mesenchymal Stem Cell Numbers for Cell-Based Therapies.

    Science.gov (United States)

    Fong, Chui-Yee; Subramanian, Arjunan; Biswas, Arijit; Bongso, Ariff

    2016-04-01

    Some cord blood banks freeze entire pieces of UC (mixed cord, MC) which after post-thaw yields mixed heterogeneous populations of mesenchymal stem cells (MSCs) from all its microanatomical compartments. Freezing of such entire tissues results in sub-optimal post-thaw cell recovery because of poor cryoprotectant diffusion and intracellular ice-formation, heat and water transport issues, and damage to intercellular junctions. To develop a simple method of harvesting pure homogeneous MSCs for cord blood banks, we compared the post-thaw behavior of three groups of frozen UC tissues: (i) freshly harvested WJ without cell separation; (ii) MSCs isolated from WJ (WJSC); and (iii) MC, WJ, and WJSC produced high post-thaw cell survival rates (93.52 ± 6.12% to 90.83 ± 4.51%) and epithelioid monolayers within 24 h in primary culture whereas post-thaw MC explants showed slow growth with mixed epithelioid and fibroblastic cell outgrowths after several days. Viability and proliferation rates of post-thawed WJ and hWJSC were significantly greater than MC. Post-thaw WJ and WJSC produced significantly greater CD24(+) and CD108(+) fluorescence intensities and significantly lower CD40(+) contaminants. Post-thaw WJ and WJSC produced significantly lesser annexin-V-positive and sub-G1 cells and greater degrees of osteogenic and chondrogenic differentiation compared to MC. qRT-PCR analysis of post-thaw MC showed significant decreases in anti-apoptotic gene expression (SURVIVIN, BCL2) and increases in pro-apoptotic (BAX) and cell cycle regulator genes (P53, P21, ROCK 1) compared to WJ and WJSC. We conclude that freezing of fresh WJ is a simple and reliable method of generating large numbers of clinically utilizable MSCs for cell-based therapies. PMID:26365815

  14. In Vitro Study on Lethal Effect of Human Choroidal Melanoma OCM-1 Cell Line by Repeating-70℃Freeze Thawing%In Vitro Study on Lethal Effect of Human Choroidal Melanoma OCM-1 Cell Line by Repeating-70℃ Freeze Thawing

    Institute of Scientific and Technical Information of China (English)

    Bin Liu; Yongping Li; Bo Zhang; Wenxin Zhang

    2007-01-01

    Objective: To investigate the effects of repeating -70℃ freeze thawing on human choroidal melanoma cell line OCM-1.Methods: OCM-1 cells were frozen by repeating -70℃ freeze thawing with various durations and frequencies. Then the inhibit rate of cells was examined by MTT essay.The cell viability was measured by monoclonal formation assay. We also used the HE staining, immunohistochemistry staining and the laser-scanning confocal microscopy (LSCM) to investigate the morphological changes of the cells.Results: The growth of OCM-1 cells was inhibited by repeating -70℃ freeze thawing in time-dependent and frequency-dependent manners (P < 0.01). Different morphous including necrosis and apoptosis of the cells could be observed after -70℃ freeze thawing by the LSCM.Conclusion: Repeating -70℃ freeze thawing can not only kill cells directly and induce considerable cells to apoptosis, but also inhibit the growth of the survivals. The kill and wound ratio of the cells disposal with different times and frequencies present variance. And the distinction when treated with different frequencies during the same time is much more significant than different times with the same frequency, which guide clinical workers to choose repeating cryotherapy with short term method instead of single cryotherapy with long term in choroidal melanoma treatment.

  15. Intracellular glycerol influences resistance to freeze stress in Saccharomyces cerevisiae: analysis of a quadruple mutant in glycerol dehydrogenase genes and glycerol-enriched cells.

    Science.gov (United States)

    Izawa, Shingo; Sato, Machiko; Yokoigawa, Kumio; Inoue, Yoshiharu

    2004-11-01

    Glycerol is well known as a cryoprotectant similar to trehalose. However, there is little information about the effects of intracellular glycerol on the freeze-thaw stress tolerance of yeast. Through analysis of a quadruple-knockout mutant of glycerol dehydrogenase genes (ara1 Delta gcy1 Delta gre3 Delta ypr1 Delta) in Saccharomyces cerevisiae, we revealed that the decrease in glycerol dehydrogenase activity led to increased levels of intracellular glycerol. We also found that this mutant showed higher tolerance to freeze stress than wild type strain W303-1A. Furthermore, we demonstrated that intracellular-glycerol-enriched cells cultured in glycerol medium acquire tolerance to freeze stress and retain high leavening ability in dough even after frozen storage for 7 days. These results suggest the possibility of using intracellular-glycerol-enriched cells to develop better frozen dough. PMID:15127164

  16. Freezing osteoblast cells attached to hydroxyapatite discs and glass coverslips: Mechanisms of damage

    Institute of Scientific and Technical Information of China (English)

    McGRATH; John

    2007-01-01

    Damage mechanisms for osteoblast cells (OBs) attached to hydroxyapatite (HA) discs and glass coverslips were comprehensively investigated. Cell-cell, cell-matrix interaction altered the cryobiological properties of cells. Attached cells were sub- ject to more severe mechanical damage than isolated cells because attached cells had larger contacting area with ice and the three dimensional movements of iso- lated cells made them more flexible than attached cells that could only deform in one dimension. Results showed that the viability of attached OB cells decreased significantly compared with the viability of isolated OB cells under the same cryo- preservation procedure. Extracellular ice, differential thermal contraction, and mechanical stresses were the major damaging factors for OB cells attached to HA discs and glass coverslips.

  17. Freezing osteoblast cells attached to hydroxyapatite discs and glass coverslips: Mechanisms of damage

    Institute of Scientific and Technical Information of China (English)

    LIU BaoLin; McGRATH John

    2007-01-01

    Damage mechanisms for osteoblast cells (OBs) attached to hydroxyapatite (HA)discs and glass coverslips were comprehensively investigated. Cell-cell, cell-matrix interaction altered the cryobiological properties of cells. Attached cells were subject to more severe mechanical damage than isolated cells because attached cells had larger contacting area with ice and the three dimensional movements of isolated cells made them more flexible than attached cells that could only deform in one dimension. Results showed that the viability of attached OB cells decreased significantly compared with the viability of isolated OB cells under the same cryopreservation procedure. Extracellular ice, differential thermal contraction, and mechanical stresses were the major damaging factors for OB cells attached to HA discs and glass coverslips.

  18. Anomalous Freezing of Nano-Confined Water in Room-Temperature Ionic Liquid 1-Butyl-3-Methylimidazolium Nitrate.

    Science.gov (United States)

    Abe, Hiroshi; Takekiyo, Takahiro; Yoshimura, Yukihiro; Saihara, Koji; Shimizu, Akio

    2016-04-18

    Non-crystal formation of ice is investigated by simultaneous X-ray diffraction and differential scanning calorimetry measurements upon cooling to -100 °C. At room temperature, size-tunable water confinement (≈20 Å size) in a room-temperature ionic liquid (RTIL, 1-butyl-3-methylimidazolium nitrate, [C4 mim][NO3 ]) exists in a water-rich region (70-90 mol % D2 O). The confined water (water pocket) is characterized by almost monodispersive size distribution. In [C4 mim][NO3 ]-x mol % D2 O (70Bragg reflections and a distinct exothermal peak indicate that crystallization/cold crystallization both of [C4 mim][NO3 ] and D2 O is suppressed, even upon slow cooling and heating. PMID:26841088

  19. Evaluation of Methylcellulose and Dimethyl Sulfoxide as the Cryoprotectants in a Serum-Free Freezing Media for Cryopreservation of Adipose-Derived Adult Stem Cells

    OpenAIRE

    Thirumala, Sreedhar; Gimble, Jeffrey M.; Devireddy, Ram V.

    2010-01-01

    Developing effective techniques for the cryopreservation of human adipose-derived adult stem cells (ASCs) could increase the usefulness of these cells in tissue engineering and regenerative medicine. To this end, we investigated the post-freeze/thaw viability and apoptotic behavior of Passage 1 (P1) adult stem cells (ASCs) in 11 different media: (i) the traditional media containing Dulbecco’s modified Eagle’s medium (DMEM) with 80% fetal calf serum (FCS) and 10% dimethyl sulfoxide (DMSO), (ii...

  20. Freezing injury in potato leaves.

    Science.gov (United States)

    Sukumaran, N P; Weiser, C J

    1972-11-01

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

  1. Anhydrobiosis and Freezing-Tolerance

    DEFF Research Database (Denmark)

    McGill, Lorraine; Shannon, Adam; Pisani, Davide;

    2015-01-01

    Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode...... Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth...

  2. Freezing and Food Safety

    Science.gov (United States)

    ... freeze well. Examples are mayonnaise, cream sauce and lettuce. Raw meat and poultry maintain their quality longer ... illness. [ Top of Page ] Does Freezing Destroy Bacteria & Parasites? Freezing to 0 °F inactivates any microbes — bacteria, ...

  3. Fusion of liposomes with the plasma membrane of epithelial cells: Fate of incorporated lipids as followed by freeze fracture and autoradiography of plastic sections

    OpenAIRE

    Knoll, G.; Burger, K.N.J.; Bron, R.; van Meer, G.; Verkleij, A. J.

    1988-01-01

    The fusion of liposomes with the plasma membrane of influenza virus- infected monolayers of an epithelial cell line, Madin-Darby canine kidney cells (van Meer et al., 1985. Biochemistry. 24:3593-3602), has been analyzed by morphological techniques. The distribution of liposomal lipids over the apical and basolateral plasma membrane domains after fusion was assessed by autoradiography of liposomal [3H]dipalmitoylphosphatidylcholine after rapid freezing or chemical fixation and further processi...

  4. Robotic milking and milk quality: effects on bacterial counts, somatic cell counts, freezing point and free fatty acids

    Directory of Open Access Journals (Sweden)

    Yvonne van der Vorst

    2010-01-01

    Full Text Available Changes in milk quality after the introduction of automatic milking systems (AM-systems on dairy farms in TheNetherlands, Germany and Denmark were examined and the data were compared with milk quality results of farms withconventional milking technology. After introduction, a small, but significant increase in total bacterial count, somatic cellcount, freezing point and free fatty acids was observed. The highest levels for total plate count and cell count are foundin the first six months after introduction. After this period the milk quality slightly improves to a more stable level.Risk factors related with milk quality concern general farm characteristics, animal health, AM-system, cleaning and cooling,housing, management skills of the farmer and the hygiene on the farm. Total plate count was significantly relatedto milk yield of the herd, cleaning of the area around the AM-system and the overall hygiene on the farm. Bulk milksomatic cell count appeared to be significantly related to milk yield of the herd and the number of milkings before replacementof the liners. An increased milking frequency is not the only explanation of increased free fatty acid levels. Technicalfactors related to free fatty acids mainly concerned the air inlet in the teat cups, bubbling (excessive air inlet and a toolong post run time of the milk pump. However, several questions regarding the causes of increased free fatty acid levelsremained unclear.

  5. Freeze-Tolerant Condensers

    Science.gov (United States)

    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.

  6. Freezing injury in onion bulb cells: I. Evaluation of the conductivity method and analysis of ion and sugar efflux from injured cells.

    Science.gov (United States)

    Palta, J P; Levitt, J; Stadelmann, E J

    1977-09-01

    Onion (Allium cepa L.) bulbs were frozen to -4 and -11 C and kept frozen for up to 12 days. After slow thawing, a 2.5-cm square from a bulb scale was transferred to 25 ml deionized H(2)O. After shaking for standard times, measurements were made on the effusate and on the effused cells. The results obtained were as follows.Even when the scale tissue was completely infiltrated, and when up to 85% of the ions had diffused out, all of the cells were still alive, as revealed by cytoplasmic streaming and ability to plasmolyze. The osmotic concentration of the cell sap, as measured plasmolytically, decreased in parallel to the rise in conductivity of the effusate. The K(+) content of the effusate, plus its assumed counterion, accounted for only 20% of the total solutes, but for 100% of the conductivity. A large part of the nonelectrolytes in the remaining 80% of the solutes was sugars.The increased cell injury and infiltration in the -11 C treatment, relative to the -4 C and control (unfrozen) treatments, were paralleled by increases in conductivity, K(+) content, sugar content, and pH of the effusate. In spite of the 100% infiltration of the tissue and the large increase in conductivity of the effusate following freezing, no increase in permeability of the cells to water could be detected.The above observations may indicate that freezing or thawing involves a disruption of the active transport system before the cells reveal any injury microscopically. PMID:16660100

  7. Ice adhesions in relation to freeze stress.

    Science.gov (United States)

    Olien, C R; Smith, M N

    1977-10-01

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

  8. Effects of the ionizing radiations, freezing and thawing duration on chicken liver cells quality

    Science.gov (United States)

    Duarte, R. C.; Araújo, M. M.; Salum, D. C.; Marchioni, E.; Villavicencio, A. L. C. H.

    2009-07-01

    All food storage processes modify the food. Irradiation reduces and could stop cell division, avoid infestation, reduce contamination and delay food decomposition. The cold chain is a succession of steps which maintains the food at low temperature. Defrosted food shall never be frozen again, the best way being to consume it quickly then avoiding multiplication and acceleration of microbial growth, which causes decay and nutrients damage. The Comet Assay indicates DNA damage and can then be used to control the overall quality of the food and in a certain extent to evaluate the damage caused by irradiation and storage on liver chicken cells. In this work, different thawing temperatures and radiation doses were checked to establish a "DNA damage index" by using the Comet Assay. Samples were irradiated in a 60Co irradiator with 1.5, 3.0 and 4.5 kGy radiation doses. Our results showed that no intact cells were detected in frozen samples: however, irradiated liver samples in natura showed some intact cells depending on the applied radiation doses.

  9. Supercooling as a viable non-freezing cell preservation method of rat hepatocytes.

    Directory of Open Access Journals (Sweden)

    O Berk Usta

    Full Text Available Supercooling preservation holds the potential to drastically extend the preservation time of organs, tissues and engineered tissue products, and fragile cell types that do not lend themselves well to cryopreservation or vitrification. Here, we investigate the effects of supercooling preservation (SCP at -4(oC on primary rat hepatocytes stored in cryovials and compare its success (high viability and good functional characteristics to that of static cold storage (CS at +4(oC and cryopreservation. We consider two prominent preservation solutions a Hypothermosol (HTS-FRS and b University of Wisconsin solution (UW and a range of preservation temperatures (-4 to -10 (oC. We find that there exists an optimum temperature (-4(oC for SCP of rat hepatocytes which yields the highest viability; at this temperature HTS-FRS significantly outperforms UW solution in terms of viability and functional characteristics (secretions and enzymatic activity in suspension and plate culture. With the HTS-FRS solution we show that the cells can be stored for up to a week with high viability (~56%; moreover we also show that the preservation can be performed in large batches (50 million cells with equal or better viability and no loss of functionality as compared to smaller batches (1.5 million cells performed in cryovials.

  10. Putting a Freeze on Liquidity

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    China raises its reserve requirement ratio for large banks to prevent its economy from overheating The People’s Bank of China, the central bank, on May 10 raised the deposit reserve requirement ratio for

  11. Temperature-sensitivity and cell biocompatibility of freeze-dried nanocomposite hydrogels incorporated with biodegradable PHBV

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qingsong, E-mail: zqs8011@163.com; Chen, Li, E-mail: chenlis@tjpu.edu.cn; Dong, Youyu; Lu, Si

    2013-04-01

    The structure, morphology, thermal behaviors and cytotoxicity of novel hydrogels, composed of poly(N-isopropylacrylamide)(PNIPAM) and biodegradable polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) under nanoclay hectorite “Laponite XLG” severed as physical cross-linker, were characterized by X-ray diffraction, scanning electron microscopy, gravimetric method, differential scanning calorimetry, and cell culture experiments. It was found that, due to the introduction of hydrophobic PHBV, the homogeneity of interior pore in the pure PNIPAM nanocomposite hydrogel was disrupted, the transparency and swelling degree gradually decreased. Although the weight ratio between PHBV and NIPAM increased from 5 to 40 wt.%, the volume phase transition temperature (VPTTs) of hydrogel were not altered compared with the pure PNIPAM nanocomposite hydrogel. No matter what PHBV content, the PHBV/PNIPAM/Hectorite hydrogels always exhibit good stimuli-responsibility. In addition, human hepatoma cells(HepG2) adhesion and spreading on the surface of PHBV-based hydrogels was greatly improved than that of pure PNIPAM nanocomposite hydrogel at 37 °C due to the introduction of PHBV. Highlights: ► Thermo-responsive and cell biocompatible hydrogels incorporated PHBV was synthesized. ► The introduction of PHBV decreases the transparency of nanocomposite hydrogel. ► The introduction of PHBV has a little shift on VPTTs of nanocomposite hydrogel. ► The HepG2 cells could adhere and spread on the surface of PHBV-based hydrogels. ► Cell sheet could be detached simultaneously from the surface of hydrogels.

  12. Active control of the nucleation temperature enhances freezing survival of multipotent mesenchymal stromal cells.

    Science.gov (United States)

    Lauterboeck, L; Hofmann, N; Mueller, T; Glasmacher, B

    2015-12-01

    Cryopreservation is a technique that has been extensively used for storage of multipotent mesenchymal stromal cells (MSCs) in regenerative medicine. Therefore, improving current cryopreservation procedures in terms of increasing cell viability and functionality is important. In this study, we optimized the cryopreservation protocol of MSCs derived from the common marmoset Callithrix jacchus (cj), which can be used as a non-human primate model in various pathological and transplantation studies and have a great potential for regenerative medicine. We have investigated the effect of the active control of the nucleation temperature using induced nucleation at a broad range of temperatures and two different dimethylsulfoxide concentrations (Me2SO, 5% (v/v) and 10%, (v/v)) to evaluate the overall effect on the viability, metabolic activity and recovery of cells after thawing. Survival rate and metabolic activity displayed an optimum when ice formation was induced at -10 °C. Cryomicroscopy studies indicated differences in ice crystal morphologies as well as differences in intracellular ice formation with different nucleation temperatures. High subzero nucleation temperatures resulted in larger extracellular ice crystals and cellular dehydration, whereas low subzero nucleation temperatures resulted in smaller ice crystals and intracellular ice formation. PMID:26499840

  13. Understanding Slag Freeze Linings

    Science.gov (United States)

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

    2014-09-01

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

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

    Science.gov (United States)

    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…

  15. A sliding cell technique for diffusion measurements in liquid metals

    Directory of Open Access Journals (Sweden)

    Yongliang Geng

    2014-03-01

    Full Text Available The long capillary and shear cell techniques are the usual methods for diffusion measurements in liquid metals. Here we present a new “sliding cell technique” to measure interdiffusion in liquid alloys, which combines the merits of these two methods. Instead of a number of shear cells, as used in the shear cell method, only one sliding cell is designed to separate and join the liquid diffusion samples. Using the sliding cell technique, the influence of the heating process (which affects liquid diffusion measurements in the conventional long capillary method can be eliminated. Time-dependent diffusion measurements at the same isothermal temperature were carried out in Al-Cu liquids. Compared with the previous results measured by in-situ X-ray radiography, the obtained liquid diffusion coefficient in this work is believed to be influenced by convective flow. The present work further supports the idea that to obtain accurate diffusion constants in liquid metals, the measurement conditions must be well controlled, and there should be no temperature gradients or other disturbances.

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

    Science.gov (United States)

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

    1992-01-01

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

  17. The performance of silicon solar cells operated in liquids

    International Nuclear Information System (INIS)

    Better performance can be achieved when the bare silicon solar cells are immersed into liquids for the enhanced heat removing. In this study, the performance of solar cells immersed in liquids was examined under simulated sunlight. To distinguish the effects of the liquid optic and electric properties on the solar cells, a comparison between immersion of the solar module and the bare solar cells was carried out. It was found that the optic properties of the liquids can cause minor efficiency changes on the solar cells, while the electric properties of the liquids, the molecular polarizable and ions, are responsible for the most of the changes. The bare solar cells immersed in the non-polar silicon oil have the best performance. The accelerated life tests were carried out at 150 deg. C high temperature and under 200 W/m2 ultraviolet light irradiation, respectively. It was found that the silicon oil has good stability. This study can give support on the cooling of the concentrated photovoltaic systems by immersing the solar cells in the liquids directly

  18. Factors affecting the use of impedance spectroscopy in the characterisation of the freezing stage of the lyophilisation process: the impact of liquid fill height in relation to electrode geometry.

    Science.gov (United States)

    Smith, Geoff; Arshad, Muhammad Sohail; Polygalov, Eugene; Ermolina, Irina

    2014-04-01

    This study aims to investigate the application of impedance spectroscopy using fixed electrode geometries on a standard glass vial in the characterisation of the freezing process of solutions at different fill liquid volumes. Impedance spectra (between 10 and 10(6) Hz) were recorded every 3 min, during the freezing cycle on a solution of 30 mg/mL sucrose contained within 10 mL glass vials having an electrode system (two thin copper foils: w, 18 mm; h, 5 mm) affixed to the external surface of the vial. A fill factor (Φ) was defined in terms of the relative height of the solution volume to the height of the electrodes from the base of the vial. Solution volumes of 1.5 to 5 mL (corresponding to Φ= 0.5-1.6) were investigated to establish the applicability of having a fixed electrode geometry for a range of solution volumes. A linear relationship between the time duration of the ice formation/solidification phase and the fill factor suggests that fixed electrode geometries may be used to investigate a range of fill volumes. The benefit of this approach is that it does not invade the solution and hence records the freezing process without providing additional nucleation sites and in a manner which is representative of the entire fill volume. PMID:24306675

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

    Science.gov (United States)

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

    1994-01-01

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

  20. Economics of a freeze desalting process using cold seawater effluent of a liquid natural gas plant. Final report. [AVCO Crystallex process

    Energy Technology Data Exchange (ETDEWEB)

    1976-03-01

    The technical feasibility and economic attractiveness of using cold seawater from an LNG plant in an adjacent seawater freeze desalting plant and the degree to which this would improve the environmental impact of the LNG plant is discussed. The basis for comparison is a secondary refrigerant process, the AVCO Crystallex process. (GRA)

  1. Fullerene solar cells with cholesteric liquid crystal doping

    Science.gov (United States)

    Jiang, Lulu; Jiang, Yurong; Zhang, Congcong; Chen, Zezhang; Qin, Ruiping; Ma, Heng

    2016-09-01

    This paper reports the doping effect of cholesteric liquid crystal 3β-Hydroxy-5-cholestene 3-oleate on polymer solar cells composed of the poly 3-hexyl thiophene and the fullerene derivative. With a doping ratio of 0.3 wt%, the device achieves an ideal improvement on the shunt resistor and the fill factor. Compared with the reference cell, the power conversion efficiency of the doped cell is improved 24%. The photoelectric measurement and the active layer characterization indicate that the self-assembly liquid crystal can improve the film crystallization and reduce the membrane defect. Project supported by the National Natural Science Foundation of China (Grant No. 61540016).

  2. The Influence of Freezing Drizzle on Wire Icing during Freezing Fog Events

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yue; NIU Shengjie; L(U) Jingjing

    2013-01-01

    Both direct and indirect effects of freezing drizzle on ice accretion were analyzed for ten freezing drizzle events during a comprehensive ice thickness,fog,and precipitation observation campaign carried out during the winter of 2008 and 2009 at Enshi Radar Station (30°17′N,109°16′E),Hubei Province,China.The growth rate of ice thickness was 0.85 mm h-1 during the freezing drizzle period,while the rate was only 0.4 mm h-1 without sleet and freezing drizzle.The rain intensity,liquid water content (LWC),and diameter of freezing drizzle stayed at low values.The development of microphysical properties of fog was suppressed in the freezing drizzle period.A threshold diameter (Dc) was proposed to estimate the influence of freezing drizzle on different size ranges of fog droplets.Fog droplets with a diameter less than Dc would be affected slightly by freezing drizzle,while larger fog droplets would be affected significantly.Dc had a correlation with the average rain intensity,with a correlation coefficient of 0.78.The relationships among the microphysical properties of fog droplets were all positive when the effect of freezing drizzle was weak,while they became poor positive correlations,or even negative correlations during freezing drizzle period.The direct contribution of freezing drizzle to ice thickness was about 14.5%.Considering both the direct and indirect effects,we suggest that freezing drizzle could act as a “catalyst” causing serious icing conditions.

  3. 冻结开关控制生物网络液体电路中的信号传输%Control of Signal Transmission Across the Liquid Circuits of Biological Network Through Freeze Switch

    Institute of Scientific and Technical Information of China (English)

    白晓丹; 刘静

    2006-01-01

    通过引入一种新概念型电开关,首次提出研究生物网络液体电路或具有普遍意义的导电性微流体系统中的电学关断问题,通过有选择性地对通路中的水性电溶液实施冻结,则其内在特定方向上传输电流的离子可因溶液冻结后绝缘性的形成而被完全阻断,而一旦复温融化后,则此微流体电路中的电流又恢复其开启状态.为初步证实上述设想,设计了相应的概念性试验,通过检测溶液或生物系统在冻结及加热时的电阻瞬态响应规律,证实了方法的可行性.总结了冻结性电开关在控制导电性液体电路方面的工作性能及其在电泳分析、液相色谱分析以及在控制神经网络中信号传输方面的潜在应用.%The electrically turning off properties of the liquid circuit in a biological network or a generalized conductive microfluidic system based on a new conception electrical switch was proposed. By selectively freezing part of the electric aqueous solution inside the circuit, the ions to conduct the electric current along a specific direction can be completely shut off due to the formation of the frozen insulation solution. After thawing, the current along the microfluidic circuit will resume its turning-on status again. For a preliminary demonstration, several conceptual experiments were performed to test the transient electrical impedances of the solution or biological system subject at freezing and heating, the convincing results were obtained. The working performances of the freezing electric switch on controlling the conductive liquid circuit were summarized, and its potential applications in electrophoretic analysis, liquid chromatogram analysis or especially controlling the signal transmission across the neural network, are suggested.

  4. 基于相场法的液态食品冷冻浓缩冰晶生长数值模拟%Numericalsimulation of ice crystal growth of liquid food freeze concentration based on phase-field method

    Institute of Scientific and Technical Information of China (English)

    陈梅英; 冯力; 欧忠辉; 林河通; 卓艳云; 陈锦权

    2014-01-01

    The quality of products produced through freeze concentration is better than that produced through evaporation concentration and has lower energy consumed. But freeze concentration has been limited for industrial production because of the loss of soluble solids caused by ice crystal entrainment. Reducing the ice crystal entrainment and losses is critical for industrial production of freeze concentration. The breakthrough is to control ice crystal growth behavior. In order to develop a freeze concentration process mathematical model for simulating the evolution of ice crystal growth from the microscopic structure, through regarding liquid food as water and solute in binary system, the phase-field model theory was applied, liquid food system was treated as water and solute in binary system. The effects of ice crystal growth and solute concentration distribution over crystallized time were studied. Results showed that the crystallized time could affect the growth of lateral branch. Ice crystal growed gradually when the main branch become thinner and the secondary dendritic arms were well-developed. Solute field and phase field profiles were consistent. The solute concentration of ice crystals contained was greater, and the regional solute concentration distribution also changed. The precipitatied solute by crystallization was not completely dissoluted into the liquid phase since the solute diffusion velocity was much less than the ice crystal growth rate. The solute concentrated on the ice front of solid liquid interface. The solute concentration distribution was different in different parts of the solid-liquid interface. The solute concentration between crystal branches was the highest since the well-developed lateral dendritic branch captured the partion of the solute. The solute of lateral interface of ice crystals was enriched. The speed in the lateral ice crystals was slower than in the tip of ice crystals, which caused not sufficiently diffusion of the solute in

  5. Electrolyte creepage barrier for liquid electrolyte fuel cells

    Science.gov (United States)

    Li, Jian; Farooque, Mohammad; Yuh, Chao-Yi

    2008-01-22

    A dielectric assembly for electrically insulating a manifold or other component from a liquid electrolyte fuel cell stack wherein the dielectric assembly includes a substantially impermeable dielectric member over which electrolyte is able to flow and a barrier adjacent the dielectric member and having a porosity of less than 50% and greater than 10% so that the barrier is able to measurably absorb and chemically react with the liquid electrolyte flowing on the dielectric member to form solid products which are stable in the liquid electrolyte. In this way, the barrier inhibits flow or creepage of electrolyte from the dielectric member to the manifold or component to be electrically insulated from the fuel cell stack by the dielectric assembly.

  6. Thermodynamics of freezing and melting.

    Science.gov (United States)

    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

  7. Improved method for freeze-fracture radioautography of tissues and cells, as applied to duodenal epithelium and thymic lymphocytes

    International Nuclear Information System (INIS)

    An improved method has been devised for the localization of radioactive substances to either one of the leaflets of cellular membranes. After tissue specimens are freeze-fractured and covered with a platinum-carbon replica, they are freeze-dried to allow coating with radioautographic emulsion at room temperature. After exposure at 4 degrees C and development, the emulsion is protected by layers of carbon and grease before the tissue underlying the replica is dissolved in sodium hypochlorite. The grease is removed in Freon 14 and the replica with its emulsion cover is mounted on a specimen grid for electron microscopic examination. The accuracy of radioactivity localization was demonstrated using 3H-thymidine-labeled liver by finding silver grains over the same sites after freeze-fracture as after thin section radioautography. Tests with 3H-methacrylate revealed that the interposition of a platinum-carbon replica decreased the radioautographic reaction by over 80%; hence, the need for long exposure. Only 67% of the silver grains came from radiation sources located beyond the upper 0.05 micron of the specimen and, therefore, the emulsion could be affected by radiation sources located not only within membrane leaflets but also in nearby cytoplasm. Thus, when 3H-fucose was injected into rats to locate newly formed glycoproteins within intestinal epithelium membranes, some of the silver grains found over E and P faces might be produced by radiation coming from the adjacent cytoplasm. To localize label within membrane leaflets in the absence of radiation sources in the cytoplasm, lymphocyte suspensions were incubated with 3H-concanavalin A at 0 degrees C. The plasmalemma radioactivity was then restricted to the two membrane leaflets, with 87-93% of the silver grains on the E leaflet and 7-13% on the P leaflet

  8. A new portable device for automatic controlled-gradient cryopreservation of blood mononuclear cells

    DEFF Research Database (Denmark)

    Hviid, L; Albeck, G; Hansen, B;

    1993-01-01

    Protection of the functional integrity of mononuclear cells stored in liquid N2 requires careful control of the freezing procedure. Consequently, optimal quality of cryopreserved cells is usually assured by freezing according to a specified time-temperature gradient generated by computer-controll......Protection of the functional integrity of mononuclear cells stored in liquid N2 requires careful control of the freezing procedure. Consequently, optimal quality of cryopreserved cells is usually assured by freezing according to a specified time-temperature gradient generated by computer......-controlled freezing devices. While such equipment offers large capacity and secures maximum survival and functional integrity of the lymphocytes upon thawing, it is quite costly and strictly stationary. We have previously developed and tested an alternative, manual device for controlled-gradient lymphocyte freezing...

  9. Influence of dough freezing on Saccharomyces cerevisiae metabolism

    Directory of Open Access Journals (Sweden)

    Pejin Dušanka J.

    2007-01-01

    Full Text Available The need to freeze dough is increasing in bakery production. Frozen dough can be stored for a long time without quality change. The capacity of bakery production can be increased in this way, and in the same time, the night shifts can be decreased. Yeast cells can be damaged by freezing process resulting in poor technological quality of dough after defrostation (longer fermentation of dough. The influence of frozen storage time of dough on survival percentage of Saccharomyces cerevisiae was investigated. Dough samples were taken after 1, 7, 14 and 28 days of frozen storage at -20°C. After defrosting, at room temperature, samples were taken from the surface and the middle part of dough (under aseptic conditions, and the percentage of living S. cerevisiae cells was determined. During frozen storage of dough, the number of living S. cerevisiae decreased. After 28 days of frozen storage, the percentage of live cells on the surface and inside the dough was 53,1% and 54,95%, respectively. The addition of k-carragenan to dough increased the percentage of living cells in the middle part of dough up to 64,63%. Pure cultures, isolated from survived S. cerevisia cells in frozen dough by agar plates method (Koch's method, were multiplied in optimal liquid medium for yeasts. The content of cytochromes in S. cerevisiae cells was determined by spectrophotometric method. The obtained results showed that the content of cytochromes in survived S. cerevisiae cells was not affected by dough freezing process. Growth rate and fermentative activity (Einchor's method were determined in multiplied cells.

  10. Physiological alterations in UV-irradiated cells: liquid holding recovery

    International Nuclear Information System (INIS)

    The biochemical and physiological alterations that occur in ultraviolet irradiated cells, during liquid holding have been studied. Incubation in buffer acts not to interfer directly with the mechanic repairs but by promoting metabolic alterations that would block some irreversible and lethal physiological responses. (L.M.J.)

  11. A review of liquid metal anode solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    ALIYA TOLEUOVA

    2013-06-01

    Full Text Available This review discusses recent advances in a solid oxide fuel cell (SOFC variant that uses liquid metal electrodes (anodes with the advantage of greater fuel tolerance and the ability to operate on solid fuel. Key features of the approach are discussed along with the technological and research challenges that need to be overcome for scale-up and commercialisation.

  12. Effects of freezing on soil temperature, freezing front propagation and moisture redistribution in peat: laboratory investigations

    Directory of Open Access Journals (Sweden)

    R. M. Nagare

    2012-02-01

    Full Text Available There are not many studies that report water movement in freezing peat. Soil column studies under controlled laboratory settings can help isolate and understand the effects of different factors controlling freezing of the active layer in organic covered permafrost terrain. In this study, four peat Mesocosms were subjected to temperature gradients by bringing the Mesocosm tops in contact with sub-zero air temperature while maintaining a continuously frozen layer at the bottom (proxy permafrost. Soil water movement towards the freezing front (from warmer to colder regions was inferred from soil freezing curves, liquid water content time series and from the total water content of frozen core samples collected at the end of freezing cycle. A substantial amount of water, enough to raise the upper surface of frozen saturated soil within 15 cm of the soil surface at the end of freezing period appeared to have moved upwards during freezing. Diffusion under moisture gradients and effects of temperature on soil matric potential, at least in the initial period, appear to drive such movement as seen from analysis of freezing curves. Freezing front (separation front between soil zones containing and free of ice propagation is controlled by latent heat for a long time during freezing. A simple conceptual model describing freezing of an organic active layer initially resembling a variable moisture landscape is proposed based upon the results of this study. The results of this study will help in understanding, and ultimately forecasting, the hydrologic response of wetland-dominated terrain underlain by discontinuous permafrost.

  13. Anti-cancer efficacy of nonthermal plasma dissolved in a liquid, liquid plasma in heterogeneous cancer cells

    Science.gov (United States)

    Nguyen, Ngoc Hoan; Park, Hyung Jun; Yang, Sang Sik; Choi, Kyeong Sook; Lee, Jong-Soo

    2016-01-01

    The therapeutic potential of nonthermal plasma for cancer treatment has been reported recently. The heterogeneity of cancer cells need to be addressed to design effective anticancer treatments. Here, we show that treatment with nonthermal atmospheric-pressure plasma dissolved in a liquid (liquid plasma) induces oxidative stress in heterogeneous populations of cancer cells and ultimately kills these cells via apoptosis, regardless of genetic status, e.g., mutations in p53 and other DNA-damage-response genes. We found that liquid plasma markedly increased the concentration of intracellular and mitochondrial reactive oxygen species (ROS), reflecting an influx from the extracellular milieu. Liquid plasma contributed to mitochondrial accumulation of ROS and depolarization of mitochondrial membrane potential with consequent cell death. Healthy normal cells, however, were hardly affected by the liquid-plasma treatment. The antioxidant N-acetylcysteine blocked liquid-plasma-induced cell death. A knockdown of CuZn-superoxide dismutase or Mn-SOD enhanced the plasma-induced cell death, whereas expression of exogenous CuZn-SOD, Mn-SOD, or catalase blocked the cell death. These results suggest that the mitochondrial dysfunction mediated by ROS production is a key contributor to liquid-plasma-induced apoptotic cell death, regardless of genetic variation. Thus, liquid plasma may have clinical applications, e.g., the development of therapeutic strategies and prevention of disease progression despite tumor heterogeneity. PMID:27364630

  14. Method and system for purification of gas/liquid streams for fuel cells or electrolysis cells

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention provides in embodiments a method for purification of inlet gas/liquid streams in a fuel cell or electrolysis cell, the fuel cell or electrolysis cell comprising at least a first electrode, an electrolyte and a second electrode, the method comprising the steps of: - providing...... at least one scrubber in the gas/liquid stream at the inlet side of the first electrode of the fuel cell or electrolysis cell; and/or providing at least one scrubber in the gas/liquid stream at the inlet side of the second electrode of the fuel cell or electrolysis cell; and - purifying the gas/liquid...... streams towards the first and second electrode; wherein the at least one scrubber in the gas/liquid stream at the inlet side of the first electrode and/or the at least one scrubber in the gas/liquid stream at the inlet side of the second electrode comprises a material suitable as an electrolyte material...

  15. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles.

    Science.gov (United States)

    Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

    2016-02-01

    Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems.

  16. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles.

    Science.gov (United States)

    Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

    2016-02-01

    Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems. PMID:26585223

  17. Functional compartmentation of the Golgi apparatus of plant cells : immunocytochemical analysis of high-pressure frozen- and freeze-substituted sycamore maple suspension culture cells.

    Science.gov (United States)

    Zhang, G F; Staehelin, L A

    1992-07-01

    The Golgi apparatus of plant cells is engaged in both the processing of glycoproteins and the synthesis of complex polysaccharides. To investigate the compartmentalization of these functions within individual Golgi stacks, we have analyzed the ultrastructure and the immunolabeling patterns of high-pressure frozen and freeze-substituted suspension-cultured sycamore maple (Acer pseudoplatanus L.) cells. As a result of the improved structural preservation, three morphological types of Golgi cisternae, designated cis, medial, and trans, as well as the trans Golgi network, could be identified. The number of cis cisternae per Golgi stack was found to be fairly constant at approximately 1, whereas the number of medial and trans cisternae per stack was variable and accounted for the varying number of cisternae (3-10) among the many Golgi stacks examined. By using a battery of seven antibodies whose specific sugar epitopes on secreted polysaccharides and glycoproteins are known, we have been able to determine in which types of cisternae specific sugars are added to N-linked glycans, and to xyloglucan and polygalacturonic acid/rhamnogalacturonan-I, two complex polysaccharides. The findings are as follows. The beta-1,4-linked d-glucosyl backbone of xyloglucan is synthesized in trans cisternae, and the terminal fucosyl residues on the trisaccharide side chains of xyloglucan are partly added in the trans cisternae, and partly in the trans Golgi network. In contrast, the polygalacturonic/rhamnogalacturonan-I backbone is assembled in cis and medial cisternae, methylesterification of the carboxyl groups of the galacturonic acid residues in the polygalacturonic acid domains occurs mostly in medial cisternae, and arabinose-containing side chains of the polygalacturonic acid domains are added to the nascent polygalacturonic acid/rhamnogalacturonan-I molecules in the trans cisternae. Double labeling experiments demonstrate that xyloglucan and polygalacturonic acid

  18. Surface freezing of water.

    Science.gov (United States)

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

    2016-01-01

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

  19. Freeze drying apparatus

    Science.gov (United States)

    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.

  20. Freeze drying method

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2002-12-01

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

  2. Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells

    OpenAIRE

    VIJ, JAGDISH; Song, Jang-Kun

    2008-01-01

    PUBLISHED Solitary wave propagation in surface stabilized ferroelectric liquid crystal cells controlled by surface anchoring of the alignment layers is investigated for different conditions of alignment on the two opposite surfaces. We show that the critical field Ec, where the speed of the solitary wave becomes zero, is finite for asymmetric alignment on two surfaces. We also show that the polar anchoring energy difference (Deltawp) between the alignment layers can be calculated by measur...

  3. Anti-cancer efficacy of nonthermal plasma dissolved in a liquid, liquid plasma in heterogeneous cancer cells

    OpenAIRE

    Ngoc Hoan Nguyen; Hyung Jun Park; Sang Sik Yang; Kyeong Sook Choi; Jong-Soo Lee

    2016-01-01

    The therapeutic potential of nonthermal plasma for cancer treatment has been reported recently. The heterogeneity of cancer cells need to be addressed to design effective anticancer treatments. Here, we show that treatment with nonthermal atmospheric-pressure plasma dissolved in a liquid (liquid plasma) induces oxidative stress in heterogeneous populations of cancer cells and ultimately kills these cells via apoptosis, regardless of genetic status, e.g., mutations in p53 and other DNA-damage-...

  4. Does Freeze-Thawing Influence the Effects of Platelet Concentrates? An In Vitro Study on Human Adipose-Derived Stem Cells.

    Science.gov (United States)

    Ceci, Caterina; Niada, Stefania; Del Fabbro, Massimo; Lolato, Alessandra; Taschieri, Silvio; Giannasi, Chiara; Brini, Anna Teresa

    2016-03-01

    Human adipose-derived stem cells (hASCs) have been proposed as a possible therapy for tissue regeneration in aesthetic, plastic, and reconstructive surgery. Today, platelet concentrates are used in a wide range of disciplines, but their storage has become a controversial aspect. The purpose of this in vitro study was to evaluate the effect of plasma rich in growth factors (PRGF), after a freeze-thawing cycle, on the proliferation and biological activity of progenitor cells involved in soft tissue healing. Different formulations of activated PRGF were added to hASCs cultured in serum-free medium. Cell proliferation was assessed by MTT test and cell count up to 7 and 12-day incubation. Osteo-differentiation ability of hASCs was also tested after 7 and 14-day incubation by alkaline phosphatase assay. The effects of 4 PRGF preparations (fresh/frozen and with/without platelets) were compared with corresponding formulations of plasma poor in growth factors and with standard medium. hASCs cultured in the presence of platelet concentrates increased proliferation rate with respect to cells grown in standard medium without significant differences among all the tested plasma formulations on cell viability up to 12 days of culture. PRGF activity is preserved after cryopreservation and platelet-rich preparations promoted osteo-differentiation of hASCs at day 7. In conclusion, PRGF supports the proliferation and the differentiation of progenitor cells in vitro also when applied after cryopreservation. Platelet concentrates, either alone or in combination with mesenchymal stem cells, might be a valuable tool in the field of tissue regeneration. PMID:26872279

  5. Liquid chromatography/Fourier transform IR spectrometry interface flow cell

    Science.gov (United States)

    Johnson, Charles C.; Taylor, Larry T.

    1986-01-01

    A zero dead volume (ZDV) microbore high performance liquid chromatography (.mu.HPLC)/Fourier transform infrared (FTIR) interface flow cell includes an IR transparent crystal having a small diameter bore therein through which a sample liquid is passed. The interface flow cell further includes a metal holder in combination with a pair of inner, compressible seals for directly coupling the thus configured spectrometric flow cell to the outlet of a .mu.HPLC column end fitting to minimize the transfer volume of the effluents exiting the .mu.HPLC column which exhibit excellent flow characteristics due to the essentially unencumbered, open-flow design. The IR beam passes transverse to the sample flow through the circular bore within the IR transparent crystal, which is preferably comprised of potassium bromide (KBr) or calcium fluoride (CaF.sub.2), so as to minimize interference patterns and vignetting encountered in conventional parallel-plate IR cells. The long IR beam pathlength and lensing effect of the circular cross-section of the sample volume in combination with the refractive index differences between the solvent and the transparent crystal serve to focus the IR beam in enhancing sample detection sensitivity by an order of magnitude.

  6. Relating Direct Methanol Fuel Cell Performance to Measurements in a Liquid Half Cell

    DEFF Research Database (Denmark)

    Pedersen, Christoffer Mølleskov; Tynelius, Oskar; Lund-Olesen, Torsten;

    2015-01-01

    allow further miniaturization or powering more advanced and more power hungry devices. The activity of fuel cell catalysts is often probed in the form of thin films in liquid half cells. However, it is challenging to mimic the conditions in an actual DMFC. On the other hand, it can also be problematic...

  7. Prevention and therapy of squamous cell carcinoma of the rodent esophagus using freeze-dried black raspberries

    Institute of Scientific and Technical Information of China (English)

    Gary D STONER; Robeena M AZIZ

    2007-01-01

    Aim: This study was conducted to determine if short-term treatment of N-nitrosomethylbenzylamine (NMBA)-induced tumors in the rat esophagus with dietary freeze-dried black raspberries (FBR) would result in tumor regression and enhanced survival of the animals. Methods: Four-week-old male Fisher-344 ratswere administered an AIN-76A control diet and injected subcutaneously with 0.5 mg/kg NMBA once per week for 15 weeks. At 19 weeks, when rats had an average of 5-6 tumors (papillomas) per esophagus, they were given a control diet contain-ing either 5%, 10%, or 20% FBR. After 7 weeks of berry treatment, all surviving rats were killed and tumor incidence, number and volume were determined. Results:Esophageal tumor incidences, numbers and volumes in NMBA-treated rats were not influenced by any of the berry treatments. There were progressive increases in the survival of NMBA-treated rats fed 5%-20% FBR diets; however, these increases were not significant. Conclusion: FBR at 5%, 10%, and 20% of the diet had no effect on the development of NMBA-induced tumors in the rat esophagus or on animal survival when administered for 7 weeks beginning at the papilloma stage of tumor development. Thus, FBR appear to have no therapeutic value in the treatment of esophageal tumors. In contrast, dietary FBR are highly effectivein preventing the development of NMBA-induced esophageal tumors in rats when administered before and during NMBA treatment or shortly after NMBA treat-ment when the esophagi contain preneoplastic (dysplastic) lesions of varyingdegrees of severity.

  8. Caffeine-induced Ca2+ transients and exocytosis in Paramecium cells. A correlated Ca2+ imaging and quenched-flow/freeze-fracture analysis.

    Science.gov (United States)

    Klauke, N; Plattner, H

    1998-01-01

    Caffeine causes a [Ca2+]i increase in the cortex of Paramecium cells, followed by spillover with considerable attenuation, into central cell regions. From [Ca2+]resti approximately 50 to 80 nm, [Ca2+]acti rises within /=2 sec. Chelation of Ca2+o considerably attenuated [Ca2+]i increase. Therefore, caffeine may primarily mobilize cortical Ca2+ pools, superimposed by Ca2+ influx and spillover (particularly in tl cells with empty trichocyst docking sites). In nd cells, caffeine caused trichocyst contents to decondense internally (Ca2+-dependent stretching, normally occurring only after membrane fusion). With 7S cells this usually occurred only to a small extent, but with increasing frequency as [Ca2+]i signals were reduced by [Ca2+]o chelation. In this case, quenched-flow and ultrathin section or freeze-fracture analysis revealed dispersal of membrane components (without fusion) subsequent to internal contents decondensation, opposite to normal membrane fusion when a full [Ca2+]i signal was generated by caffeine stimulation (with Ca2+i and Ca2+o available). We conclude the following. (i) Caffeine can mobilize Ca2+ from cortical stores independent of the presence of Ca2+o. (ii) To yield adequate signals for normal exocytosis, Ca2+ release and Ca2+ influx both have to occur during caffeine stimulation. (iii) Insufficient [Ca2+]i increase entails caffeine-mediated access of Ca2+ to the secretory contents, thus causing their decondensation before membrane fusion can occur. (iv) Trichocyst decondensation in turn gives a signal for an unusual dissociation of docking/fusion components at the cell membrane. These observations imply different threshold [Ca2+]i-values for membrane fusion and contents discharge.

  9. Low contaminant formic acid fuel for direct liquid fuel cell

    Science.gov (United States)

    Masel, Richard I.; Zhu, Yimin; Kahn, Zakia; Man, Malcolm

    2009-11-17

    A low contaminant formic acid fuel is especially suited toward use in a direct organic liquid fuel cell. A fuel of the invention provides high power output that is maintained for a substantial time and the fuel is substantially non-flammable. Specific contaminants and contaminant levels have been identified as being deleterious to the performance of a formic acid fuel in a fuel cell, and embodiments of the invention provide low contaminant fuels that have improved performance compared to known commercial bulk grade and commercial purified grade formic acid fuels. Preferred embodiment fuels (and fuel cells containing such fuels) including low levels of a combination of key contaminants, including acetic acid, methyl formate, and methanol.

  10. Freeze-thaw lysates of Plasmodium falciparum-infected red blood cells induce differentiation of functionally competent regulatory T cells from memory T cells

    OpenAIRE

    Finney, Olivia C; Lawrence, Emma; Gray, Alice P; Njie, Madi; Riley, Eleanor M.; Walther, Michael

    2012-01-01

    In addition to naturally occurring regulatory T (nTreg) cells derived from the thymus, functionally competent Treg cells can be induced in vitro from peripheral blood lymphocytes in response to TCR stimulation with cytokine costimulation. Using these artificial stimulation conditions, both naïve as well as memory CD4+ T cells can be converted into induced Treg (iTreg) cells, but the cellular origin of such iTreg cells in vivo or in response to more physiologic stimulation with pathogen-derive...

  11. THERMAL EVALUATION OF CONTAMINATED LIQUID ONTO CELL FLOORS

    Energy Technology Data Exchange (ETDEWEB)

    (NOEMAIL), J

    2009-05-04

    For the Salt Disposition Integration Project (SDIP), postulated events in the new Salt Waste Processing Facility (SWPF) can result in spilling liquids that contain Cs-137 and organics onto cell floors. The parameters of concern are the maximum temperature of the fluid following a spill and the time required for the maximum fluid temperature to be reached. Control volume models of the various process cells have been developed using standard conduction and natural convection relationships. The calculations are performed using the Mathcad modeling software. The results are being used in Consolidated Hazards Analysis Planning (CHAP) to determine the controls that may be needed to mitigate the potential impact of liquids containing Cs-137 and flammable organics that spill onto cell floors. Model development techniques and the ease of making model changes within the Mathcad environment are discussed. The results indicate that certain fluid spills result in overheating of the fluid, but the times to reach steady-state are several hundred hours. The long times allow time for spill clean up without the use of expensive mitigation controls.

  12. Evaluation of the ability of primary selective enrichment to resuscitate heat-injured and freeze-injured Listeria monocytogenes cells.

    OpenAIRE

    Budu-Amoako, E; Toora, S; Ablett, R F; J. Smith

    1992-01-01

    Resuscitation rates of injured Listeria monocytogenes on conventional selective Listeria enrichment broth and nonselective Trypticase soy broth containing 0.6% yeast extract were compared. Cells were heated to 60 degrees C for 5 min or frozen at -20 degrees C for 7 days. Inoculation of Trypticase soy broth-yeast extract with the stressed cells resulted in growth that was superior to that in Listeria enrichment broth. Injured cells were fully recovered at 6 to 8 h.

  13. Mycobacterium bovis bacillus Calmette-Guérin killed by extended freeze-drying targets plasmacytoid dendritic cells to regulate lung inflammation.

    Science.gov (United States)

    Lagranderie, Micheline; Abolhassani, Mohammad; Vanoirbeek, Jeroen A J; Lima, Carla; Balazuc, Anne-Marie; Vargaftig, B Boris; Marchal, Gilles

    2010-01-15

    We have previously shown that bacillus Calmette-Guérin (BCG) inactivated by extended freeze-drying (EFD) reduces airway hyperresponsiveness, whereas live and heat-killed BCG fail to do so. However, the cells involved in the protective effect and the signaling and transcriptional networks that could reprogram T cell commitment after EFD BCG treatment remained to be elucidated. We investigated whether EFD BCG targets plasmacytoid dendritic cells (pDCs) potentially involved in the polarization of regulatory T cells (Tregs) and the transcriptional factors that regulate allergic inflammation. OVA-sensitized mice were s.c. injected with EFD, live, or heat-killed BCG. We analyzed after the injection of the various BCG preparations: 1) pDCs recruited in the draining lymph nodes (day 4); 2) transcription factors involved in inflammation and T cell commitment in spleen and lungs after OVA challenge (day 28). Airway hyperresponsiveness and transcription factors were determined after in vivo depletion of pDCs or Tregs in EFD BCG-treated and OVA-challenged mice. EFD BCG reduced inflammation via the recruitment of pDCs polarizing the differentiation of naive CD4+ T lymphocytes into Tregs. In vivo, pDC or Treg depletion at the time of EFD BCG treatment abrogated the protection against inflammation. EFD BCG treatment upregulated Forkhead-winged helix transcription factor (Treg signature) and downregulated GATA-3 and RORgammat (Th2 and Th17 signatures) more efficiently than live and heat-killed BCG. Moreover, only EFD BCG enhanced peroxisome proliferator-activated receptor gamma expression and blocked NF-kappaB activation, cyclooxygenase expression, and p38 MAPK phosphorylation. EFD BCG reduced allergic inflammation by recruiting pDCs that promoted Tregs; EFD BCG acted as a peroxisome proliferator-activated receptor gamma agonist and thus could be used in asthma and other inflammatory diseases. PMID:20007537

  14. Elastic Properties of Nematic Liquid Crystals Formed by Living and Migrating Cells

    CERN Document Server

    Kemkemer, R; Kaufmann, D; Gruler, H; Kemkemer, Ralf; Kling, Dieter; Kaufmann, Dieter; Gruler, Hans

    1998-01-01

    In culture migrating and interacting amoeboid cells can form nematic liquid crystal phases. A polar nematic liquid crystal is formed if the interaction has a polar symmetry. One type of white blood cells (granulocytes) form clusters where the cells are oriented towards the center. The core of such an orientational defect (disclination) is either a granulocyte forced to be in an isotropic state or another cell type like a monocyte. An apolar nematic liquid crystal is formed if the interaction has an apolar symmetry. Different cell types like human melanocytes (=pigment cells of the skin), human fibroblasts (=connective tissue cells), human osteoblasts (=bone cells), human adipocytes (= fat cells) etc., form an apolar nematic liquid crystal. The orientational elastic energy is derived and the orientational defects (disclination) of nematic liquid crystals are investigated. The existence of half-numbered disclinations show that the nematic phase has an apolar symmetry. The density- and order parameter dependence...

  15. Using Peltier cells to study solid liquid vapour transitions and supercooling

    Science.gov (United States)

    Torzo, Giacomo; Soletta, Isabella; Branca, Mario

    2007-05-01

    We propose an apparatus for teaching experimental thermodynamics in undergraduate introductory courses, using thermoelectric modules and a real-time data acquisition system. The device may be made at low cost, still providing an easy approach to the investigation of liquid solid and liquid vapour phase transitions and of metastable states (supercooling). The thermoelectric module (a technological evolution of the thermocouple) is by itself an interesting subject that offers a clear example of both thermo-electric (Seebeck effect) and electro-thermal (Peltier effect) energy transformation. We report here some cooling/heating measurements for several liquids and mixtures, including water, salt/water, ethanol/water and sodium acetate, showing how to evaluate the phenomena of freezing point depression and elevation, and how to evaluate the water latent heat.

  16. PREPARATION AND CHARACTERIZATION OF FREEZE DRIED CRYSTALS OF IBUPROFEN

    Directory of Open Access Journals (Sweden)

    Dixit Mudit

    2011-12-01

    Full Text Available Ibuprofen, an anti-inflammatory drug, exhibits poor water solubility and flow properties.. Crystallization medium used for freeze dried crystals of Ibuprofen consisted of Isopropyl alcohol and water (50:50% respectively. Freeze dried crystals were characterized by differential scanning calorimetry, Infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. Micromeritic and mechanical property and dissolution behavior studies were carried out. Process variables such as amount of bridging liquid, stirring time and duration of stirring were optimized. Dissolution profile of the freeze dried crystals was compared with pure sample and recrystallized sample. Freeze dried crystals exhibited decreased crystallinity and improved micromeritic properties. The dissolution of the freeze dried crystals was improved compared with pure sample.

  17. Harnessing the energy accompanying freezing

    Energy Technology Data Exchange (ETDEWEB)

    Akyurt, M., E-mail: makyurt@kau.edu.s [Departments of Mechanical Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Tuerkmen, N. [Departments of Mechanical Engineering, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2011-05-15

    Research highlights: {yields} Ice pressurization allows the burst and leak testing of practically all tubular materials. {yields} The assembly can be made fully portable for maintenance operations without the use of liquid CO{sub 2} and N{sub 2}. {yields} Ice pressurization can work where conventional interference fitting, axial pressing and heat treatment fail. {yields} Uniform pressures can be developed in ice pressurization as opposed to Herzian distributions under plungers. -- Abstract: The progression of freezing of water inside a pipe is reviewed, with special emphasis on bursting. The process of pressure rise in confined bodies of water is discussed. The development of a method utilizing liquid carbon dioxide and liquid nitrogen, for the development of pressures inside closed containers is summarized. Then a novel method, utilizing mechanical refrigeration, is explained for the generation of high pressures. An experimental setup for the latter technique is described and results of experiments are summarized. A number of ways of utilizing the ice-pressurization technique are presented. Certain characteristics and advantages of ice-pressurization are enumerated as regards to burst and leak testing. It is noted that a number of other techniques such as shrink fitting, embossing and compaction of powders also seem to be particularly suitable. It is concluded that, with the advent of the portable and novel chilling apparatus, new vistas are approachable for undertaking maintenance operations in hospitals, power plants, nuclear facilities, and other systems that require uninterrupted operation.

  18. Ultrasound-Assisted Freezing

    Science.gov (United States)

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

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

  19. Biological activity and mechanical stability of sol-gel-based biofilters using the freeze-gelation technique for immobilization of Rhodococcus ruber.

    Science.gov (United States)

    Pannier, Angela; Mkandawire, Martin; Soltmann, Ulrich; Pompe, Wolfgang; Böttcher, Horst

    2012-02-01

    Biofilters with long lifetime and high storage stability are very important for bioremediation processes to ensure the readiness at the occurrence of sudden contaminations. By using the freeze-gelation technique, living cells can be immobilized within a mechanically and chemically stable ceramic-like matrix. Due to a freeze-drying step, the embedded microorganisms are converted into a preserved form. In that way, they can be stored under dry conditions, which comply better with storage, transport, and handling requirements. Thus, in contrast to other immobilization techniques, there is no need for storage in liquid or under humid atmosphere. The biological activity, mechanical strength, and the structure of the biologically active ceramic-like composites (biocers) produced by freeze gelation have been investigated by using the phenol-degrading bacteria Rhodococcus ruber as model organism. Samples of freeze-gelation biocers have been investigated after defined storage periods, demonstrating nearly unchanged mechanical strength of the immobilization matrix as well as good storage stability of the activity of the immobilized cells over several months of storage at 4 °C. Repeated-batch tests demonstrated further that the freeze-gelation biocers can be repeatedly used over a period of more than 12 months without losing its bioactivity. Thus, these results show that freeze-gelation biocers have high potential of being scaled up from laboratory test systems to applications in real environment because of their long bioactivity as well as mechanical stability.

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

    Science.gov (United States)

    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.

  1. Cytotoxic Evaluation of e-Liquid Aerosol using Different Lung-Derived Cell Models

    Directory of Open Access Journals (Sweden)

    Stefanie Scheffler

    2015-10-01

    Full Text Available The in vitro toxicological evaluation of e-liquid aerosol is an important aspect of consumer protection, but the cell model is of great significance. Due to its water solubility, e-liquid aerosol is deposited in the conducting zone of the respiratory tract. Therefore, primary normal human bronchial epithelial (NHBE cells are more suitable for e-liquid aerosol testing than the widely used alveolar cell line A549. Due to their prolonged lifespan, immortalized cell lines derived from primary NHBE cells, exhibiting a comparable in vitro differentiation, might be an alternative for acute toxicity testing. In our study, A549 cells freshly isolated NHBE cells and the immortalized cell line CL-1548 were exposed at the air-liquid interface to e-liquid aerosol and cigarette mainstream smoke in a CULTEX® RFS compact module. The cell viability was analyzed 24 h post-exposure. In comparison with primary NHBE cells, the CL-1548 cell line showed lower sensitivity to e-liquid aerosol but significantly higher sensitivity compared to A549 cells. Therefore, the immortalized cell line CL-1548 is recommended as a tool for the routine testing of e-liquid aerosol and is preferable to A549 cells.

  2. Effect of freezing and thawing rates on denaturation of proteins in aqueous solutions.

    Science.gov (United States)

    Cao, Enhong; Chen, Yahuei; Cui, Zhanfeng; Foster, Peter R

    2003-06-20

    The freeze denaturation of model proteins, LDH, ADH, and catalase, was investigated in absence of cryoprotectants using a microcryostage under well-controlled freezing and thawing rates. Most of the experimental data were obtained from a study using a dilute solution with an enzyme concentration of 0.025 g/l. The dependence of activity recovery of proteins on the freezing and thawing rates showed a reciprocal and independent effect, that is, slow freezing (at a freezing rate about 1 degrees C/min) and fast thawing (at a thawing rate >10 degrees C/min) produced higher activity recovery, whereas fast freezing with slow thawing resulted in more severe damage to proteins. With minimizing the freezing concentration and pH change of buffer solution by using a potassium phosphate buffer, this phenomenon could be ascribed to surface-induced denaturation during freezing and thawing process. Upon the fast freezing (e.g., when the freezing rate >20 degrees C/min), small ice crystals and a relatively large surface area of ice-liquid interface are formed, which increases the exposure of protein molecules to the ice-liquid interface and hence increases the damage to the proteins. During thawing, additional damage to proteins is caused by recrystallization process. Recrystallization exerts additional interfacial tension or shear on the entrapped proteins and hence causes additional damage to the latter. When buffer solutes participated during freezing, the activity recovery of proteins after freezing and thawing decreased due to the change of buffer solution pH during freezing. However, the patterns of the dependence on freezing and thawing rates of activity recovery did not change except for that at extreme low freezing rates (solutions could be reduced by changing the buffer type and composition and by optimizing the freezing-thawing protocol.

  3. Mechano-freezing of the ambient water

    CERN Document Server

    Zhang, Xi; Zou, Bo; Sun, Chang Q

    2013-01-01

    Raman spectroscopy examination of the 25 deg-C water freezing under compression revealed transition from 1.35 GPa to 0.86 GPa upon ice being formed at continued volume change. The transition is associated with a slight blue shift of the high-frequency phonon (omiga_H ~ 3120 cm-1) and creation of the low-frequency phonons (Omiga_L ~ 200 cm-1). In the liquid and in the solid phase, the increased pressure softens the Omiga_H and stiffens the Omida_L, which indicates the presence of the inter-electron-pair repulsion in both liquid and solid water.

  4. A surface plasmon enabled liquid-junction photovoltaic cell.

    Science.gov (United States)

    Lee, Woo-ram; Mubeen, Syed; Stucky, Galen D; Moskovits, Martin

    2015-01-01

    Plasmonic nanosystems have recently been shown to be capable of functioning as photovoltaics and of carrying out redox photochemistry, purportedly using the energetic electrons and holes created following plasmonic decay as charge carriers. Although such devices currently have low efficiency, they already manifest a number of favorable characteristics, such as their tunability over the entire solar spectrum and a remarkable resistance to photocorrosion. Here, we report a plasmonic photovoltaic using a 25 μm thick electrolytic liquid junction which supports the iodide/triiodide (I-/I3-) redox couple. The device produces photocurrent densities in excess of 40 μA cm(-2), an open circuit voltage (Voc) of ∼0.24 V and a fill factor of ∼0.5 using AM 1.5 G solar radiation at 100 mW cm(-2). The photocurrent and the power conversion efficiency are primarily limited by the low light absorption in the 2-D gold nanoparticle arrays. The use of a liquid junction greatly reduces dielectric breakdown in the oxide layers utilized, which must be very thin for optimal performance, leading to a great improvement in the long-term stability of the cell's performance. PMID:25740725

  5. Transmission electron microscope cells for use with liquid samples

    Energy Technology Data Exchange (ETDEWEB)

    Khalid, Waqas; Alivisatos, Paul A.; Zettl, Alexander K.

    2016-08-09

    This disclosure provides systems, methods, and devices related to transmission electron microscopy cells for use with liquids. In one aspect a device includes a substrate, a first graphene layer, and a second graphene layer. The substrate has a first surface and a second surface. The first surface defines a first channel, a second channel, and an outlet channel. The first channel and the second channel are joined to the outlet channel. The outlet channel defines a viewport region forming a though hole in the substrate. The first graphene layer overlays the first surface of the substrate, including an interior area of the first channel, the second channel, and the outlet channel. The second graphene layer overlays the first surface of the substrate, including open regions defined by the first channel, the second channel, and the outlet channel.

  6. Liquid flow cells having graphene on nitride for microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adiga, Vivekananda P.; Dunn, Gabriel; Zettl, Alexander K.; Alivisatos, A. Paul

    2016-09-20

    This disclosure provides systems, methods, and apparatus related to liquid flow cells for microscopy. In one aspect, a device includes a substrate having a first and a second oxide layer disposed on surfaces of the substrate. A first and a second nitride layer are disposed on the first and second oxide layers, respectively. A cavity is defined in the first oxide layer, the first nitride layer, and the substrate, with the cavity including a third nitride layer disposed on walls of the substrate and the second oxide layer that define the cavity. A channel is defined in the second oxide layer. An inlet port and an outlet port are defined in the second nitride layer and in fluid communication with the channel. A plurality of viewports is defined in the second nitride layer. A first graphene sheet is disposed on the second nitride layer covering the plurality of viewports.

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

    Science.gov (United States)

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

    2004-06-01

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

  8. Examination of the Blood Groups and Biologal Activity of the Freeze-drying Red Blood Cells%冻干前后红细胞血型及生物活性指标的检测

    Institute of Scientific and Technical Information of China (English)

    吴学忠; 刘忠; 吕蓉; 李敏; 李素萍; 於娟; 赵丹

    2011-01-01

    目的 检测冻干前、后红细胞血型抗原及其生物学活性,了解冻干前、后红细胞血型抗原及其生物学活性的变化情况.方法红细胞血型抗原的检测采用血型血清学方法,2,3-DPG和ATP用ELISA法.结果在ABO、Rh、MNSs、Kell、Duffy、P血型抗原中,冷冻前、冻干后红细胞血型抗原一致;在Lewis血型抗原中,冷冻前、冻干后红细胞血型抗原有变化.冷冻前、冻干后红细胞2,3-DPG和ATP含量均无明显变化.结论冷冻前、冻干后红细胞Lewis血型系统中的Lea和Leb血型抗原变化有明显差异;冷冻前、冻干后红细胞2,3-DPG和ATP含量变化无统计学意义.%Objective To detect the blood group antigens, the levels of 2,3-DPG and ATP of red blood cells (RBCs) before and after freeze-drying. Also the changes of blood group antigens and biological activity of RBCs before and after RBCs freeze-drying was observed. Methods The blood group antigens of RBCs were detected by the blood group serology, the levels of 2,3-DPG and ATP were detected by ELISA. Results The blood group antigens of RBCs were the same as before and after freeze-drying about ABO, Rh, MNSs, Kell, Duffy and P blood group systems. But the blood group antigens of RBCs of Lewis blood group systems were different before and after freeze-drying. The levels of 2,3-DPG and ATP of RBCs before and after freeze-drying didn't change significantly. Conclusion The Lea and Leb blood group antigens of RBCs before and after freeze-drying of Lewis blood group systems have changed significantly. The levels of 2,3-DPG and ATP of RBCs before and after freeze-drying havn't chenged significantly.

  9. Theoretical prediction of 'optimal' freezing programmes

    NARCIS (Netherlands)

    Woelders, H.; Chaveiro, A.

    2004-01-01

    We have developed a quantitative description of the osmotic behaviour of cells during freezing without a presupposed value of the cooling rate. Instead, at all times the intracellular supercooling is maximised provided that it does not exceed a predetermined value 'p' (e.g., 2°C). This should preclu

  10. Freeze-drying of lactic acid bacteria.

    Science.gov (United States)

    Fonseca, Fernanda; Cenard, Stéphanie; Passot, Stéphanie

    2015-01-01

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

  11. Freezing-induced deformation of biomaterials in cryomedicine

    Science.gov (United States)

    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

  12. Survival of Suspension-cultured Sycamore Cells Cooled to the Temperature of Liquid Nitrogen.

    Science.gov (United States)

    Sugawara, Y; Sakai, A

    1974-11-01

    Suspension-cultured cells of sycamore (Acer pseudoplatanus L.) which were immersed in liquid nitrogen after prefreezing to the temperatures from -30 to -50 C in the presence of dimethylsulfoxide and glucose as cryoprotective additive could proliferate vigorously when rewarmed rapidly in water at 40 C. For maintaining high viability of the cells after immersion in liquid nitrogen, it seems to be essential to use the cells at the later lag phase or the early cell division phase. This study provides a possibility for long term preservation in liquid nitrogen of plant-cultured lines.

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

    Science.gov (United States)

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

    2008-06-01

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

  14. A novel and versatile flash-freezing approach for evaluating the health of Delta Smelt.

    Science.gov (United States)

    Teh, Swee J; Baxa, Dolores V; Hammock, Bruce G; Gandhi, Saikrithika A; Kurobe, Tomofumi

    2016-01-01

    A common approach used to assess environmental impacts in aquatic environments is to measure indicators of stress (biomarkers) and condition of fish within ecosystems. Particularly in estuarine ecosystems with multiple stressors, it is often desirable to quantify a suite of biological endpoints that (1) reflect fish condition at several levels of biological organization and time scales and (2) are sensitive to a range of environmental stressors. However, established methods of preservation and processing of fish for specific endpoints are often incompatible. Here, we developed a novel flash-freezing approach for assessing the health of a small, sensitive fish, the endangered Delta Smelt (Hypomesus transpacificus) after collections from the San Francisco Estuary (SFE). We assess whether flash-freezing the entire fish ensures effective preservation of multiple tissues for subsequent biomarker analyses by comparing measurements of fresh to frozen tissue. Tissues included brain, gill, and liver for enzyme activity, kidney and spleen for pathogens, and gills, liver, and gonads for histopathology and reproduction. Although flash-freezing in liquid nitrogen altered the length, weight, and condition factor of Delta Smelt, the percent changes were small (artefacts were observed in ovaries, but did not hinder the identification and interpretation of cell types and oocyte stages. Freezing did not alter bacterial isolation or the activities of ethoxyresorufin-0-deethylase (EROD) or acetylcholinesterase (AChE), but had a small, negative influence on sodium potassium adenosine triphosphatase (ATPase) activity. Thus, flash-freezing in the field is a versatile preservation method for Delta Smelt, allowing for multiple tissue collections and bioassays from an individual tiny fish exposed to a wide range of natural and anthropogenic stressors. Similar methodology may be applicable to other species for which a range of biological endpoints and histopathology data are needed. PMID

  15. Development of metal-carbon eutectic cells for application as high temperature reference points in nuclear reactor severe accident tests: Results on the Fe-C, Co-C, Ti-C and Ru-C alloys' melting/freezing transformation temperature under electromagnetic induction heating

    International Nuclear Information System (INIS)

    With the aim of reducing the high temperature measurement uncertainty of nuclear reactor severe accident experimental tests at the PLINIUS platform in Cadarache Research Centre, France, a variety of graphite cells containing a metal-carbon eutectic mix have been tested to assess the melting/freezing temperature reproducibility and their feasibility as calibration cells for thermometers. The eutectic cells have been thermally cycled in an induction furnace to assess the effect of heating/cooling rate, metal purity, graphite crucible design, and binary system constituents on the eutectic transformation temperature. A bi-chromatic pyrometer was used to perform temperature measurements in the graphite cell black cavity containing the metal-carbon eutectic mix. The eutectic points analyzed are all over 1100 C and cover an almost thousand degree span, i.e. from the Fe-Fe3C to the Ru-C eutectic. The induction heating permitted the attainment of heating and cooling rates of over 200 C/min under an inert atmosphere. The conducted tests allowed the determination of general trends and peculiarities of the solid. liquid transformation temperature under non-equilibrium and non-steady-state conditions of a variety of eutectic alloys (Fe-C, Co-C, Ti-C and Ru-C binary systems). (authors)

  16. Evaluation of Sericin as a Fetal Bovine Serum-Replacing Cryoprotectant During Freezing of Human Mesenchymal Stromal Cells and Human Osteoblast-Like Cells

    OpenAIRE

    Verdanova, Martina; Pytlik, Robert; Kalbacova, Marie Hubalek

    2014-01-01

    A reliable, cryoprotective, xeno-free medium suitable for different cell types is highly desirable in regenerative medicine. There is danger of infection or allergic reaction with the use of fetal bovine serum (FBS), making it problematic for medical applications. The aim of the present study was to develop an FBS-free cryoprotective medium for human mesenchymal stromal cells (hMSCs; primary cells) and immortalized human osteoblasts (SAOS-2 cell line). Furthermore, we endeavored to eliminate ...

  17. Asseessment of therapeutic effect of liquid nitrogen freezing combined with photodynamic therapy in the treatment of multiple anal condyloma acuminatum%液氮喷冻联合光动力治疗肛管内泛发尖锐湿疣疗效评价

    Institute of Scientific and Technical Information of China (English)

    孙洁; 李铁军

    2014-01-01

    目的:评价液氮喷冻联合光动力治疗肛管内泛发尖锐湿疣的疗效。方法:选择26例肛管内泛发尖锐湿疣患者,肛门镜扩开肛门,用液氮枪喷冻治疗约1 min,然后用肛门镜中间柱体将浸有10%盐酸氨酮戊酸散的纱布挤压在疣体上约1 h;艾拉激光照射20 min。结果:治愈率96.15%,平均治疗2.96次。结论:液氮喷冻联合光动力治疗肛管内泛发尖锐湿疣有效。%Objective:To assess the efficacy of liquid nitrogen freezing combined with photodynamic therapy in the treatment of multiple anal condyloma acuminatum (MACA). Methods: Twenty six patients with MACA were selected. The anoscope was inserted into the anus and the MACA were freezed with liquid nitrogen for 1 minute. And then the gauze soaked in 10% aminolevulinic acid hydrochloride were pressed on the warts by the cylinder of anoscope for 1 hour. After that the warts were irradiated with laser for 20 minutes. Results:The cure rate was 96. 15%. The average times of treatment was 2. 96. Conclusion: Liquid nitrogen freezing combined with photodynamic therapy was effective in the treatment of multiple anal condyloma acuminatum.

  18. Microscale electrochemical cell using plaster (CaSO4 as liquid junction

    Directory of Open Access Journals (Sweden)

    Yuthapong Udnan

    2008-10-01

    Full Text Available A microscale apparatus for electrochemical cell in which plaster (CaSO4 was used as liquid junction has been developed. A glass tube (0.5 cm ID x 5.0 cm was used to prepare each half-cell. The potentials of the resulting galvanic cells were measured by a multimetre and were compared to those of the galvanic cells in which agar was used as liquid junction. It was found that the potentials produced by the galvanic cells with plaster as liquid junction are not significantly different from those of the cells with agar as liquid junction and close to the theoretical values. In addition, when the developed apparatus was used for the study of electrolysis of potassium iodide solution, it was found that the electrolytic cell made from the microscale apparatus with plaster liquid junction can distinctly separate the reactions occurring at the anode and the cathode. Moreover, the lifetime of the plaster liquid junction is much greater than that of the agar liquid junction.

  19. 食用菌等生鲜食品液态N2和CO2深冷冻结技术%Liquid nitrogen and carbon dioxide cryogenic freezing technology of edible fungi and other fresh foods

    Institute of Scientific and Technical Information of China (English)

    吴向金; 张丽霞; 张书玉; 邹宇; 顾振新; 汪志君

    2011-01-01

    The latest research progress and application of quick freezing technology of edible fungi and other fresh foods were introduced. Some investigations on quick freezing of edible fungi and other fresh foods, including method ,equipment, freezing and storage processes, were reviewed. Moreover, development prospect of edible fungi and other fresh foods was forecasted.%介绍了食用菌等生鲜食品速冻技术的最新研究进展与应用情况,就速冻食用菌等生鲜食品加工技术的方法、设备、冻结与冻藏工艺进行综述,并对食用菌等生鲜食品的开发利用前景进行了展望.

  20. Single cell-gap transflective liquid crystal device created by controlling the pretilt angle using a liquid crystalline reactive monomer.

    Science.gov (United States)

    Jeon, Eun-Young; Kim, Ki-Han; Lee, Ji-Hoon; Yoon, Tae-Hoon

    2011-12-01

    We present a single cell-gap transflective liquid crystal (LC) device using a homogeneous alignment polyimide (H-PI) mixed with a liquid crystalline reactive monomer that is able to vertically align the LC. We obtain two different pretilt angles in each pixel through the region by region control of the UV exposure time. The smaller pretilt angle is used to obtain a half-wave phase retardation for the transmissive part, whereas the larger pretilt angle is used to obtain a quarter-wave phase retardation for the reflective part. PMID:22273954

  1. A three-cell liquid hydrogen target for an extended focal plane polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Golovanov, L.B.; Borzounov, Yu.T.; Piskunov, N.M.; Tsvinev, A.P. [Joint Inst. for Nuclear Research, Dubna (Russian Federation). Lab. of High Energy; Ball, J.; Chesny, Ph.; Gheller, J.M.; Guillier, G.; Ladygin, V.P.; Theure, Ph.; Tomasi-Gustafsson, E. [Laboratoire National Saturne, Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France)

    1996-12-31

    This article describes the design and working principle of a 3-cell liquid hydrogen target produced for the high-energy deuteron polarimeter HYPOM. This target uses liquid Helium as a cooling agent. After a general description of the apparatus, tests and operating modes are thoroughly explained. In particular the air controlled self regulation of Helium flow in the cryostat to stabilize the liquid hydrogen level is presented. (author). 12 refs.; Submitted to Nuclear Instruments and Methods, A (NL).

  2. Posttransfusion survival of red cells frozen for 8 weeks after 42-day liquid storage in AS-3

    International Nuclear Information System (INIS)

    Current standards recommend that red cells (RBCs) should be frozen within 6 days of donation. There are situations, however, in which it is desirable to freeze RBCs that are older than 6 days, such as for the salvage of rare or autologous units. To determine the therapeutic efficacy of RBCs frozen after prolonged liquid storage, standard units were drawn from nine normal donors and stored at 4 degrees C for 42 days in a nutrient-additive solution, AS-3. 51CrRBC survival assays were performed (24-hour survival: 78.2 +/- 12.4%; n = 8) and the units were frozen at -80 degrees C in glycerol for 8 weeks. After deglycerolization, the mean RBC recovery was 81.0 +/- 4.1 percent and the mean 24-hour 51Cr survival was 78.0 +/- 9.1 percent. The index of therapeutic effectiveness (ITE) was determined by multiplying the postdeglycerolization 24-hour 51Cr survival by the mean RBC recovery (63.3 +/- 9.2). ITE values greater than 60 percent (75% 51Cr survival x 80% RBC recovery) were considered acceptable. Mean adenosine triphosphate levels declined from an initial 3.81 +/- 0.56 micromol per g of hemoglobin to 2.33 +/- 0.55 micromol per g after frozen storage. These findings show that an acceptable percentage of RBCs survives frozen storage after maximum liquid storage (mean ITE greater than 60%). If necessary, RBCs stored in AS-3 can be frozen at any time before 42 days

  3. Influence of freezing and thawing cycles on mechanical properties of closed-cell expanded perlite cemented soil%冻融循环对闭孔珍珠岩水泥土力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    侯宇慧; 申向东

    2013-01-01

    Due to poor frost resistance of cement-soil,in permafrost and seasonal frozen soil area,the application and promotion of the soil cement is subject to a certain limit,how to improve the strength and durability of cemented soil in repeated freeze-thaw conditions to ensure the service life of the engineering is the key for further promotion and application of soil cement material in cold regions.By adding closed-cell expanded perlite in cemented soil,it came to the strength that cemented soil in different closed-cell expanded perlite under freezing and thawing cycles,analyzed the effect of freezing and thawing cycles on closed-cell expanded perlite and the changes before and after freezing and thawing cycles closed-cell expanded perlite cemented soil.The cemented soil adding closed-cell expanded perlite are preliminary analyzed.%由于水泥土抗冻性能较差,在多年冻土和季节性冻土地区,水泥土的应用和推广受到了一定的限制,如何提高反复冻融条件下水泥土的强度和耐久性,保证工程的使用寿命,是水泥土材料在寒冷地区进一步推广应用的关键.通过在水泥土中加入闭孔珍珠岩,得出水泥土在不同闭孔珍珠岩掺量下冻融循环后的强度值,分析了冻融循环次数对闭孔珍珠岩水泥土性能的影响及冻融循环前后闭孔珍珠岩水泥土强度变化,对掺入闭孔珍珠岩的水泥土做了初步的机理分析.

  4. Accurate assessment of cell density in low cellular liquid-based cervical cytology

    NARCIS (Netherlands)

    Siebers, A.G.; Laak, J.A.W.M. van der; Huberts-Manders, R.; Vedder, J.E.M.; Bulten, J.

    2013-01-01

    A. G. Siebers, J. A. W. M. van der Laak, R. Huberts-Manders, J. E. M. Vedder and J. Bulten Accurate assessment of cell density in low cellular liquid-based cervical cytology Objective: Scant cellularity is the most important source of unsatisfactory liquid-based cytology. Although still being debate

  5. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

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

  6. Capital stock management during a recession that freezes credit markets

    NARCIS (Netherlands)

    Caulkins, J.P.; Feichtinger, G.; Grass, D.; Hartl, R.F.; Kort, Peter; Seidl, A.

    2015-01-01

    This paper considers the problem of how to price a conspicuous product while maintaining liquidity during a recession which both reduces demand and freezes credit markets. Reducing price would help maintain cash flow, but low prices can erode brand image and, hence, long-term sales. The paper extend

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

    Science.gov (United States)

    Abdelnaby, Abdelhady Abdelhakeam

    1988-12-01

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

  8. Liquid crystal cell design of VGA field sequential color LCoS display

    Science.gov (United States)

    Liu, Yanyan; Geng, Weidong; Dai, Yongping

    2009-07-01

    The design of liquid crystal cell is an important factor to determine the display quality of LCoS display device. The goal of this paper is to gain VGA field sequential color (FSC) LCoS device used for near-to-eye system. The characteristics of optics and electrooptics for the twist nematic liquid crystal material and the material requirements of the FSC LCoS were studied. The LCOS liquid crystal cell optimized by dynamic parameter space method had an uniform reflectivity (about 90%) for the light with wave length from 450nm to 650nm. Both considering the electrooptic response curve of liquid crystal and the relationship between the contrast ratio and pixel size, we determined to use high speed twist nematic liquid crystal working in normally white mode. The liquid crystal cell gap and the pixel size were determined as 2.5um and 12um, respectively. The VGA FSC LCoS device was fabricated with SMIC 0.35um CMOS process and filled with LC-A liquid crystal of Merck in Varitronix. The measurement showed that the response time of liquid crystal from light to dark was 1.8ms and from dark to light was 4.4ms. The contrast ratio is bigger than 50:1. The LCoS displays well.

  9. Seasonal Variation in the Hepatoproteome of the Dehydration- and Freeze-Tolerant Wood Frog, Rana sylvatica

    Directory of Open Access Journals (Sweden)

    Jon P. Costanzo

    2011-11-01

    Full Text Available Winter’s advent invokes physiological adjustments that permit temperate ectotherms to cope with stresses such as food shortage, water deprivation, hypoxia, and hypothermia. We used liquid chromatography (LC in combination with tandem mass spectrometry (MS/MS quantitative isobaric (iTRAQ™ peptide mapping to assess variation in the abundance of hepatic proteins in summer- and winter-acclimatized wood frogs (Rana sylvatica, a northerly-distributed species that tolerates extreme dehydration and tissue freezing during hibernation. Thirty-three unique proteins exhibited strong seasonal lability. Livers of winter frogs had relatively high levels of proteins involved in cytoprotection, including heat-shock proteins and an antioxidant, and a reduced abundance of proteins involved in cell proliferation, protein synthesis, and mitochondrial function. They also exhibited altered levels of certain metabolic enzymes that participate in the biochemical reorganization associated with aphagia and reliance on energy reserves, as well as the freezing mobilization and post-thaw recovery of glucose, an important cryoprotective solute in freezing adaptation.

  10. Nonenzymatic cryogenic isolation of therapeutic cells: novel approach for enzyme-free isolation of pancreatic islets using in situ cryopreservation of islets and concurrent selective freeze destruction of acinar tissue.

    Science.gov (United States)

    Taylor, Michael J; Baicu, Simona C

    2014-01-01

    Cell-based therapies, which all involve processes for procurement and reimplantation of living cells, currently rely upon expensive, inconsistent, and even toxic enzyme digestion processes. A prime example is the preparation of isolated pancreatic islets for the treatment of type 1 diabetes by transplantation. To avoid the inherent pitfalls of these enzymatic methods, we have conceptualized an alternative approach based on the hypothesis that cryobiological techniques can be used for differential freeze destruction of the pancreas (Px) to release islets that are selectively cryopreserved in situ. Pancreata were procured from juvenile pigs using approved procedures. The concept of cryoisolation is based on differential processing of the pancreas in five stages: 1) infiltrating islets in situ preferentially with a cryoprotectant (CPA) cocktail via antegrade perfusion of the major arteries; 2) retrograde ductal infusion of water to distend the acinar; 3) freezing the entire Px solid to dithizone for identification of intact islets and with Syto 13/PI for fluorescence viability testing and glucose-stimulated insulin release assessment. As predicted, the cryoisolate contained small fragments of residual tissue comprising an amorphous mass of acinar tissue with largely intact and viable (>90%) embedded islets. Islets were typically larger (range 50-500 µm diameter) than their counterparts isolated from juvenile pigs using conventional enzyme digestion techniques. Functionally, the islets from replicate cryoisolates responded to a glucose challenge with a mean stimulation index = 3.3 ± 0.7. An enzyme-free method of islet isolation relying on in situ cryopreservation of islets with simultaneous freeze destruction of acinar tissue is feasible and proposed as a new and novel method that avoids the problems associated with conventional collagenase digestion methods. PMID:23992741

  11. Elucidating through-plane liquid water profile in a polymer electrolyte membrane fuel cell.

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun (University of California, Irvine, CA); Chen, Ken Shuang

    2010-10-01

    In this paper, a numerical model incorporating micro-porous layers (MPLs) is presented for simulating water transport within the gas diffusion layers (GDLs) and MPLs as well as across their interfaces in a polymer electrolyte membrane (PEM) fuel cell. One-dimensional analysis is conducted to investigate the impacts of MPL and GDL properties on the liquid-water profile across the anode GDL-MPL and cathode MPL-GDL regions. Furthermore, two-dimensional numerical simulations that take MPLs into account are also carried out to elucidate liquid water transport, particularly through-plane liquid-water profile in a PEM fuel cell. Results from case studies are presented.

  12. Tracking Traction Force Changes of Single Cells on the Liquid Crystal Surface

    Directory of Open Access Journals (Sweden)

    Chin Fhong Soon

    2015-01-01

    Full Text Available Cell migration is a key contributor to wound repair. This study presents findings indicating that the liquid crystal based cell traction force transducer (LCTFT system can be used in conjunction with a bespoke cell traction force mapping (CTFM software to monitor cell/surface traction forces from quiescent state in real time. In this study, time-lapse photo microscopy allowed cell induced deformations in liquid crystal coated substrates to be monitored and analyzed. The results indicated that the system could be used to monitor the generation of cell/surface forces in an initially quiescent cell, as it migrated over the culture substrate, via multiple points of contact between the cell and the surface. Future application of this system is the real-time assaying of the pharmacological effects of cytokines on the mechanics of cell migration.

  13. Influence of dough freezing on Saccharomyces cerevisiae metabolism

    OpenAIRE

    Pejin Dušanka J.; Došanović Irena S.; Popov Stevan D.; Suturović Zvonimir J.; Ranković Jovana A.; Dodić Siniša N.; Dodić Jelena M.; Vučurović Vesna M.

    2007-01-01

    The need to freeze dough is increasing in bakery production. Frozen dough can be stored for a long time without quality change. The capacity of bakery production can be increased in this way, and in the same time, the night shifts can be decreased. Yeast cells can be damaged by freezing process resulting in poor technological quality of dough after defrostation (longer fermentation of dough). The influence of frozen storage time of dough on survival percentage of Saccharomyces cerevisiae was ...

  14. Immersion freezing of biological particles at LACIS

    Science.gov (United States)

    Clauss, T.; Hartmann, S.; Temkiv, T. S.; Augustin, S.; Gosewinkel Karlson, U.; Sahyoun, M. M.; Niedermeier, D.; Wex, H.; Voigtländer, J.; Raddatz, M.; Stratmann, F.

    2012-04-01

    Biological particles, especially bacteria being ubiquitous in the atmosphere, belong to the most efficient ice nuclei (IN) (Möhler, 2008) and hence might have a large impact on weather and climate. In this study, the immersion freezing behavior of different size segregated biological particles is investigated at the laminar flow tube LACIS (Leipzig Aerosol Cloud Interaction Simulator, Hartmann et al., 2011). For these experiments, SNOMAX and outer membrane vesicles (OMV) are used as IN. SNOMAX industrially produced from Pseudomonas-syringae bacteria, which are very ice nucleation active, can be seen as a proxy for ice nucleating bacteria in general. On the surface of these bacteria, ice nucleating proteins that initiate the freezing are situated (Maki et al., 1974). Additionally, it has been found that some ice nucleating bacteria strains have the ability to produce OMV, i.e., strangulated parts of the bacterial cell consisting of the same membrane material (Phelps et al., 1986). These OMV might contain the same ice nucleating proteins on their surface and thus might be able to nucleate ice as well. The OMV used in our experiments were extracted from bacteria cultivated from rain samples collected in Denmark from 30 m height. In our experiments, the biological particles are suspended in air via atomization, size selected by means of a Differential Mobility Particle Sizer, and then fed into LACIS. In LACIS, well defined droplets are produced by activating the biological particles to cloud droplets, so that each droplet contains only one biological particle. By decreasing the temperature in LACIS, these droplets are frozen. To determine the ice fraction, i.e., the fraction of frozen droplets to all particles, the liquid and frozen droplets are distinguished by means of a newly self-built optical device, which is positioned under LACIS, using the depolarization of light scattered by a single particle. The ice fractions are measured as a function of temperature and

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

    Science.gov (United States)

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

    2016-01-18

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

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

    Science.gov (United States)

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

    2016-01-18

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

  17. Ionic liquid-tethered Graphene Oxide/Ionic Liquid Electrolytes for Highly Efficient Dye Sensitized Solar Cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: Ionic liquid-tethered graphene oxide (IL-GO) are prepared by tethering 1-(3-aminopropyl)-3-methylimi-dazolium bromide to graphene oxide (GO), and followed by anion-exchange with bis(trifluoromethanesulfonyl)imide ions (TFSI−). Environmental friendly ionic liquid-based composite electrolyte for dye sensitized solar cells (DSSCs) without volatile organic solvents is prepared from IL-GO and 1-propyl-3-methylimidazolium iodide (PMII). Incorporation of proper amount of IL-GO significantly increased the conductivity of the electrolyte, the open circuit voltage, the short circuit current density and the conversion efficiency of DSSCs. The dye-sensitized solar cells (DSSCs) containing 4 wt% of IL-GO composite electrolytes show an overall power conversion efficiency of 7.04% under simulated AM 1.5 solar spectrum irradiation at 100 mW cm−2. These results indicate that the DSSCs based on IL-GO/IL composite electrolytes could overcome the drawbacks of volatile liquid electrolytes, and offer a feasible method to fabricate DSSCs in future practical applications

  18. Acid-Fast Staining and Petroff Hausser Chamber Counting of Mycobacterial Cells in Liquid Suspension

    OpenAIRE

    Treuer, Robin; Haydel, Shelley E.

    2011-01-01

    Accurate and rapid cell counts of mycobacterial species in culture are difficult to obtain. Here, a method using modified Kinyoun acid-fast staining was adapted for use with a Petroff-Hausser sperm and bacteria cell counting chamber by using a liquid suspension staining technique. Cell counts obtained by this method were compared to viable cell counts by agar plate counting, revealing accurate correlation.

  19. Solid and liquid spectroscopic analysis (SALSA) -- A soft x-ray spectroscopy endstation with a novel flow-through liquid cell

    Energy Technology Data Exchange (ETDEWEB)

    Blum, M.; Weinhardt, L.; Fuchs, O.; Bar, M.; Zhang, Y.; Weigand, M.; Krause, S.; Pookpanratana, S.; Hofmann, T.; Yang, W.; Denlinger, J. D.; Umbach, E.; Heske, C.

    2009-08-06

    We present a novel synchrotron endstation with a flow-through liquid cell designed to study the electronic structure of liquids using soft x-ray spectroscopies. In this cell, the liquid under study is separated from the vacuum by a thin window membrane, such that the sample liquid can be investigated at ambient pressure. The temperature of the probing volume can be varied in a broad range and with a fast temperature response. The optimized design of the cell significantly reduces the amount of required sample liquid and allows the use of different window membrane types necessary to cover a broad energy range. The liquid cell is integrated into the solid and liquid spectroscopic analysis SALSA endstation that includes a high-resolution, high-transmission x-ray spectrometer and a state-of-the-art electron analyzer. The modular design of SALSA also allows the measurement of solid-state samples. The capabilities of the liquid cell and the x-ray spectrometer are demonstrated using a resonant inelastic x-ray scattering map of a 25 wt percent NaOD solution.

  20. Miniaturized cavity ring-down detection in a liquid flow cell

    NARCIS (Netherlands)

    Bahnev, B.; Sneppen, van der L.; Wiskerke, A.E.; Ariese, F.; Gooijer, C.; Ubachs, W.M.G.

    2005-01-01

    A novel method for applying cavity ring-down spectroscopy in the liquid phase, compatible with LC analyses, is presented. The core of the setup is a home-built cavity ring-down flow cell (cell volume 12 muL) that is constructed using a silicon rubber spacer, which is clamped leak-tight between two h

  1. Low creep and hysteresis silicon load cell based on a force-to-liquid pressure transformation

    NARCIS (Netherlands)

    Zwijze, Robert A.F.; Wiegerink, Remco J.; Lammerink, Theo S.J.; Elwenspoek, Miko

    1998-01-01

    Important problems in load cells are creep and hysteresis. Expensive high grade steels are used in order to reduce these effects. In this paper a silicon load cell design is presented which is based on a force-to-liquid-pressure transformation. The design is insensitive to hysteresis and creep, can

  2. Picoliter Drop-On-Demand Dispensing for Multiplex Liquid Cell Transmission Electron Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Joseph P.; Parent, Lucas R.; Cantlon, Joshua; Eickhoff, Holger; Bared, Guido; Evans, James E.; Gianneschi, Nathan C.

    2016-06-03

    Liquid Cell Transmission Electron Microscopy (LCTEM) provides a unique insight into the dynamics of nanoparticles in solution. Controlling the mixing of multiple solutions within the liquid cells remains a key hurdle in our ability to study nanoparticle formation/modifications through conventional synthesis i.e. by mixing solutions. Here, we report that piezo dispensing techniques, allow for the mixing of multiple solutions directly within the viewing area. This technique deposits pL droplets of various aqueous and organic solutions onto the liquid cell window, prior to assembly of the cell in a fully controlled manner. This proof of concept shows the great potential for using picoliter dispensing in combination with LCTEM to observe nanoparticle synthesis or modification by solution phase mixing and the creation of chemical gradients.

  3. Securitization, transparency, and liquidity

    OpenAIRE

    Pagano, M.; Volpin, P.

    2012-01-01

    We present a model in which issuers of asset backed securities choose to release coarse information to enhance the liquidity of their primary market, at the cost of reducing secondary market liquidity or even causing it to freeze. The degree of transparency is inefficiently low if the social value of secondary market liquidity exceeds its private value. We analyze various types of public intervention — mandatory transparency standards, provision of liquidity to distressed banks or secondary m...

  4. Evaluation of the Activities of Antioxidant Enzyme and Lysosomal Enzymes of the Longissimus dorsi Muscle from Hanwoo (Korean Cattle) in Various Freezing Conditions.

    Science.gov (United States)

    Kang, Sun Moon; Kang, Geunho; Seong, Pil-Nam; Park, Beomyoung; Kim, Donghun; Cho, Soohyun

    2014-01-01

    This study was conducted to evaluate the activities of antioxidant enzyme (glutathione peroxidase (GSH-Px)) and lysosomal enzymes (alpha-glucopyranosidase (AGP) and beta-N-acetyl-glucosaminidase (BNAG)) of the longissimus dorsi (LD) muscle from Hanwoo (Korean cattle) in three freezing conditions. Following freezing at -20, -60, and -196℃ (liquid nitrogen), LD samples (48 h post-slaughter) were treated as follows: 1) freezing for 14 d, 2) 1 to 4 freeze-thaw cycles (2 d of freezing in each cycle), and 3) refrigeration (4℃) for 7 d after 7 d of freezing. The control was the fresh (non-frozen) LD. Freezing treatment at all temperatures significantly (pcycles and even for 7 d of refrigeration after freezing. These findings suggest that freezing has remarkable effects on the activities of antioxidant enzyme and lysosomal enzymes of Hanwoo beef in any condition. PMID:26761669

  5. Freezing point depression in model Lennard-Jones solutions

    Science.gov (United States)

    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.

  6. Isolation and characterization of a freeze-tolerant diploid derivative of an industrial baker's yeast strain and its use in frozen doughs.

    Science.gov (United States)

    Teunissen, Aloys; Dumortier, Françoise; Gorwa, Marie-Françoise; Bauer, Jürgen; Tanghe, An; Loïez, Annie; Smet, Peter; Van Dijck, Patrick; Thevelein, Johan M

    2002-10-01

    The routine production and storage of frozen doughs are still problematic. Although commercial baker's yeast is highly resistant to environmental stress conditions, it rapidly loses stress resistance during dough preparation due to the initiation of fermentation. As a result, the yeast loses gassing power significantly during storage of frozen doughs. We obtained freeze-tolerant mutants of polyploid industrial strains following screening for survival in doughs prepared with UV-mutagenized yeast and subjected to 200 freeze-thaw cycles. Two strains in the S47 background with a normal growth rate and the best freeze tolerance under laboratory conditions were selected for production in a 20-liter pilot fermentor. Before frozen storage, the AT25 mutant produced on the 20-liter pilot scale had a 10% higher gassing power capacity than the S47 strain, while the opposite was observed for cells produced under laboratory conditions. AT25 also retained more freeze tolerance during the initiation of fermentation in liquid cultures and more gassing power during storage of frozen doughs. Other industrially important properties (yield, growth rate, nitrogen assimilation, and phosphorus content) were very similar. AT25 had only half of the DNA content of S47, and its cell size was much smaller. Several diploid segregants of S47 had freeze tolerances similar to that of AT25 but inferior performance for other properties, while an AT25-derived tetraploid, TAT25, showed only slightly improved freeze tolerance compared to S47. When AT25 was cultured in a 20,000-liter fermentor under industrial conditions, it retained its superior performance and thus appears to be promising for use in frozen dough production. Our results also show that a diploid strain can perform at least as well as a tetraploid strain for commercial baker's yeast production and usage. PMID:12324320

  7. Effect of a pre-freezing treatment with cholesterol-loaded cyclodextrins on boar sperm longevity, capacitation dynamics, ability to adhere to porcine oviductal epithelial cells in vitro and DNA fragmentation dynamics.

    Science.gov (United States)

    Tomás, C; Blanch, E; Fazeli, A; Mocé, E

    2013-01-01

    The aim of this work was to examine how a pre-freezing treatment with cholesterol-loaded cyclodextrins (CLC) affects boar sperm longevity, capacitation dynamics, ability to bind to a porcine telomerase-immortalised oviductal epithelial cell line (TERT-OPEC) in vitro and DNA integrity dynamics after freeze-thawing. Although the samples treated with CLC exhibited lower sperm quality than the control samples (P0.05) after long-term incubation (26h at 37 or 16°C). Additionally, the CLC-treated spermatozoa underwent similar capacitation and DNA fragmentation dynamics as the control spermatozoa (P>0.05). However, CLC-treated spermatozoa were better able to bind to TERT-OPEC in vitro (POPEC in vitro, which could have an effect on the establishment of the sperm reservoir in the ampullary--isthmic junction in vivo. Additionally, frozen-thawed spermatozoa can be stored at 16°C for at least 6h without a significant observable decline in sperm quality, which could be beneficial for the transport of thawed diluted doses of spermatozoa from the laboratory to the farm. PMID:23036662

  8. Freezing in porous media: Phase behavior, dynamics and transport phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Wettlaufer, John S. [Yale Univ., New Haven, CT (United States)

    2012-12-21

    This research was focused on developing the underlying framework for the mechanisms that control the nature of the solidification of a broad range of porous media. To encompass the scope of porous media under consideration we considered material ranging from a dilute colloidal suspension to a highly packed saturated host matrix with a known geometry. The basic physical processes that occur when the interstitial liquid phase solidifies revealed a host of surprises with a broad range of implications from geophysics to materials science and engineering. We now understand that ostensibly microscopic films of unfrozen liquid control both the equilibrium and transport properties of a highly packed saturated host matrix as well as a rather dilute colloidal suspension. However, our description of the effective medium behavior in these settings is rather different and this sets the stage for the future research based on our past results. Once the liquid phase of a saturated relatively densely packed material is frozen, there is a rich dynamical behavior of particles for example due to the directed motion driven by thermomolecular pressure gradients or the confined Brownian motion of the particles. In quite striking contrast, when one freezes a dilute suspension the behavior can be rather more like that of a binary alloy with the particles playing the role of a ``solute''. We probed such systems quantitatively by (i) using X ray photon correlation spectroscopy (XPCS) and Small Angle X-ray Scattering (SAXS) at the Advanced Photon Source at Argonne (ii) studying the Argonne cell in the laboratory using optical microscopy and imagery (because it is not directly visible while in the vacuum can). (3) analyzed the general transport phenomena within the framework of both irreversible thermodynamics and alloy solidification and (4) applied the results to the study of the redistribution of solid particles in a frozen interstitial material. This research has gone a long way

  9. A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90° twisted cell

    Science.gov (United States)

    Lin, Yi-Hsin; Chen, Ming-Syuan; Lin, Wei-Chih; Tsou, Yu-Shih

    2012-07-01

    A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90° twisted cell (T-PNLC) is demonstrated. T-PNLC consists of three layers. Liquid crystal (LC) directors in the two layers near glass substrates are orthogonal to each other and those two layers modulate two eigen-polarizations of an incident light. As a result, two eigen-polarizations of an incident light experience the same phase shift. In the middle layer, LC directors are perpendicular to the glass substrate and contribute no phase shift. The phase shift of T-PNLC is electrically tunable and polarization-independent. T-PNLC does not require any bias voltage for operation. The phase shift is 0.28 π rad for the voltage of 30 Vrms. By measuring and analyzing the optical phase shift of T-PNLC at the oblique incidence of transverse magnetic wave, the pretilt angle of LC directors and the effective thickness of three layers are obtained and discussed. The potential applications are spatial light modulators, laser beam steering, and micro-lens arrays.

  10. Fundamentals of freeze-drying.

    Science.gov (United States)

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

    2002-01-01

    Given the increasing importance of reducing development time for new pharmaceutical products, formulation and process development scientists must continually look for ways to "work smarter, not harder." Within the product development arena, this means reducing the amount of trial and error empiricism in arriving at a formulation and identification of processing conditions which will result in a quality final dosage form. Characterization of the freezing behavior of the intended formulation is necessary for developing processing conditions which will result in the shortest drying time while maintaining all critical quality attributes of the freeze-dried product. Analysis of frozen systems was discussed in detail, particularly with respect to the glass transition as the physical event underlying collapse during freeze-drying, eutectic mixture formation, and crystallization events upon warming of frozen systems. Experiments to determine how freezing and freeze-drying behavior is affected by changes in the composition of the formulation are often useful in establishing the "robustness" of a formulation. It is not uncommon for seemingly subtle changes in composition of the formulation, such as a change in formulation pH, buffer salt, drug concentration, or an additional excipient, to result in striking differences in freezing and freeze-drying behavior. With regard to selecting a formulation, it is wise to keep the formulation as simple as possible. If a buffer is needed, a minimum concentration should be used. The same principle applies to added salts: If used at all, the concentration should be kept to a minimum. For many proteins a combination of an amorphous excipient, such as a disaccharide, and a crystallizing excipient, such as glycine, will result in a suitable combination of chemical stability and physical stability of the freeze-dried solid. Concepts of heat and mass transfer are valuable in rational design of processing conditions. Heat transfer by conduction

  11. Results of the development of electrochemical cells for the measurement of oxygen activity in liquid sodium

    International Nuclear Information System (INIS)

    Results of the development and testing of electrochemical cells for the measurement of oxygen activity in liquid sodium are given. A ThO2-Y2O3 solid electrolyte of high corrosion resistance in liquid sodium has been used for the construction of the cells. A design, which reduces thermal and mechanical stresses to the cells, has been applicated. A device 'Oxylyt' has been developed for reading the cell signals. During the period of development 180 electrochemical cells and about 10 devices 'Oxylyt' have been tested. The investigations were performed at experimental sodium loops, at the radioactive circuit of the reactor BR-10 and at the second circuit of the reactor station BN-350. Recommendation are given for the application of the cells for oxygen measurement in sodium at experimental rigs and industrial stations. (author)

  12. Effect of freezing on rabbit cultured chondrocytes

    Directory of Open Access Journals (Sweden)

    R.R Filgueiras

    2011-02-01

    Full Text Available This work evaluated the effect of freezing on chondrocytes maintained in culture, aiming the establishment of a cell bank for future application as heterologous implant. Chondrocytes extracted from joint cartilage of nine healthy New Zealand White rabbits were cultivated and frozen with the cryoprotector 5% dimethylsulfoxide for six months. Phenotypic and scanning electron microscopy analyses were carried out to identify morphological and functional differences between fresh and thawed cells. After enzymatic digestion, a total of 4.8x10(5cells per rabbit were obtained. Fresh chondrocytes showed a high mitotic rate and abundant matrix was present up to 60 days of culture. Loss of phenotypic stability was notable in the thawed chondrocytes, with a low labeling of proteoglycans and weak immunostaining of type II collagen. The present study showed important loss of chondrocyte viability under the freezing conditions. For future in vivo studies of heterologous implant, these results suggests that a high number of cells should be implanted in the host site in order to achieve an adequate number of viable cells. Furthermore, the chondrocytes should be implanted after two weeks of culture, when the highest viability rate is found

  13. Freezing of Water in a Slab with Boundary COnditions of the Third Kind

    Institute of Scientific and Technical Information of China (English)

    Bu-XuanWang; JiMa

    1994-01-01

    Predictions for freezing heat transfer in a slab with convertive boundary conditions at the cold surlace are obtained from heat balance integral approximations,which consider conduction as the only mode of heat transfer in both the solid and liquid and consider durations of precooling and freezing in the heat transfer process.The thermal penetration dimensionless parameter α is presented to distingush two cases of freezing,and analytical results for α≥1 are given in this paper.An experimental investigation on freezing of water is peroted for comparison with the one-dimensional conduction model to show that experimental modeling for freezing heat transfer with convective boundary conditions using pelter devices is feasible,The comparison also demonstrated that the freezing rate in this case was decreased by natural convection in the liquid just as freezing with boundary conditions of the first kind and phase change approximately proceeds linearly with time rather than with square root of time at the initiation of freezing.

  14. Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

    Science.gov (United States)

    Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo

    2016-09-01

    A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 μg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 μg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption.

  15. Ultrasound-assisted dispersive liquid-liquid microextraction of tetracycline drugs from egg supplements before flow injection analysis coupled to a liquid waveguide capillary cell.

    Science.gov (United States)

    Rodríguez, Michael Pérez; Pezza, Helena Redigolo; Pezza, Leonardo

    2016-09-01

    A simple, rapid, and efficient ultrasound-assisted dispersive liquid-liquid microextraction (US-DLLME) method was developed for extraction of tetracycline residues from egg supplement samples, with subsequent determination by flow injection analysis (FIA) coupled to a liquid waveguide capillary cell (LWCC) and a controlled temperature heating bath. Tetracyclines react with diazotized p-sulfanilic acid, in a slightly alkaline medium, to form azo compounds that can be measured at 435 nm. The reaction sensitivity improved substantially (5.12-fold) using an in-line heating temperature of 45 °C. Multivariate methodology was used to optimize the factors affecting the extraction efficiency, considering the volumes of extraction and disperser solvents, sonication time, extraction time, and centrifugation time. Good linearity in the range 30-600 μg L(-1) was obtained for all the tetracyclines, with regression coefficients (r) higher than 0.9974. The limits of detection ranged from 6.4 to 11.1 μg L(-1), and the recoveries were in the range 85.7-96.4 %, with relative standard deviation lower than 9.8 %. Analyte recovery was improved by approximately 6 % when the microextraction was assisted by ultrasound. The results obtained with the proposed US-DLLME-FIA method were confirmed by a reference HPLC method and showed that the egg supplement samples analyzed were suitable for human consumption. PMID:27379391

  16. Liquid Water Transport in the Reactant Channels of Proton Exchange Membrane Fuel Cells

    Science.gov (United States)

    Banerjee, Rupak

    Water management has been identified as a critical issue in the development of PEM fuel cells for automotive applications. Water is present inside the PEM fuel cell in three phases, i.e. liquid phase, vapor phase and mist phase. Liquid water in the reactant channels causes flooding of the cell and blocks the transport of reactants to the reaction sites at the catalyst layer. Understanding the behavior of liquid water in the reactant channels would allow us to devise improved strategies for removing liquid water from the reactant channels. In situ fuel cell tests have been performed to identify and diagnose operating conditions which result in the flooding of the fuel cell. A relationship has been identified between the liquid water present in the reactant channels and the cell performance. A novel diagnostic technique has been established which utilizes the pressure drop multiplier in the reactant channels to predict the flooding of the cell or the drying-out of the membrane. An ex-situ study has been undertaken to quantify the liquid water present in the reactant channels. A new parameter, the Area Coverage Ratio (ACR), has been defined to identify the interfacial area of the reactant channel which is blocked for reactant transport by the presence of liquid water. A parametric study has been conducted to study the effect of changing temperature and the inlet relative humidity on the ACR. The ACR decreases with increase in current density as the gas flow rates increase, removing water more efficiently. With increase in temperature, the ACR decreases rapidly, such that by 60°C, there is no significant ACR to be reported. Inlet relative humidity of the gases does change the saturation of the gases in the channel, but did not show any significant effect on the ACR. Automotive powertrains, which is the target for this work, are continuously faced with transient changes. Water management under transient operating conditions is significantly more challenging and has not

  17. Determination of azimuthal anchoring strength in twisted nematic liquid crystal cells using heterodyne polarimeter.

    Science.gov (United States)

    Yu, Tsung-Chih; Lo, Yu-Lung; Huang, Rei-Rong

    2010-09-27

    Two external-field-free methods are presented for measuring the azimuthal anchoring strength in twisted nematic liquid crystal (TNLC) cells. For asymmetrical TNLC samples, the twist angle is derived from the phase of the detected signal in a phase-sensitive heterodyne polarimeter and is then used to calculate the weak anchoring strength directly. The measurement resolution which is found to be about 0.01 μJ/m(2) makes the present method sensitive enough for the LC-based bio-sensing application. Using the proposed method, the weak azimuthal anchoring strength of a composite liquid crystal mixture (40% LCT-061153 + 60% MJO-42761) in contact with a plasma-alignment layer is found to be 7.19 μJ/m(2). For symmetrical TNLC samples, the liquid crystals are injected into a wedge cell, and the two-dimensional distributions of the twist angle and cell gap are extracted from the detected phase distribution using a genetic algorithm (GA). The azimuthal anchoring strength is then obtained by applying a fitting technique to the twist angle vs. cell gap curve. Utilizing the proposed approach, it is shown that the strong anchoring strength between a rubbed polyimide (PI) alignment layer and E7 liquid crystal is around 160 μJ/m(2) while that between a rubbed PI alignment layer and MLC-7023 liquid crystal is approximately 32 μJ/m(2). PMID:20941014

  18. Liquid balance monitoring inside conventional, Retrofit, and bio-reactor landfill cells

    Energy Technology Data Exchange (ETDEWEB)

    Abichou, Tarek, E-mail: abichou@eng.fsu.edu [Department of Civil and Environmental Engineering, Florida State University, 2525 Pottsdamer Street, Tallahassee, FL 32311 (United States); Barlaz, Morton A. [Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Green, Roger; Hater, Gary [Waste Management Inc., Cincinnati, OH 45211 (United States)

    2013-10-15

    Highlights: • The Retrofit, Control, and As-Built cells received 48, 14, and 213 L Mg{sup −1} (liters of liquids per metric ton of waste). • The leachate collection system yielded 60, 57 and 198 L Mg{sup −1} from the Retrofit, Control, and As-Built cells. • The head on liner in all cells was below regulatory limits. • Measured moisture content of the waste samples was consistent with that calculated from accumulated liquid by balance. • The in-place saturated hydraulic conductivity of the MSW was calculated to be in the range of 10{sup −8} to 10{sup −7} m s{sup −1}. - Abstract: The Outer Loop landfill bioreactor (OLLB) in Louisville, KY, USA has been the site of a study to evaluate long-term bioreactor performance at a full-scale operational landfill. Three types of landfill units were studied including a conventional landfill (Control cell), a new landfill area that had an air addition and recirculation piping network installed as waste was being placed (As-Built cell), and a conventional landfill that was modified to allow for liquids recirculation (Retrofit cell). During the monitoring period, the Retrofit, Control, and As-Built cells received 48, 14, and 213 L Mg{sup −1} (liters of liquids per metric ton of waste), respectively. The leachate collection system yielded 60, 57 and 198 L Mg{sup −1} from the Retrofit, Control, and As-Built cells, respectively. The head on liner in all cells was below regulatory limits. In the Control and As-Built cells, leachate head on liner decreased once waste placement stopped. The measured moisture content of the waste samples was consistent with that calculated from the estimate of accumulated liquid by the liquid balance. Additionally, measurements on excavated solid waste samples revealed large spatial variability in waste moisture content. The degree of saturation in the Control cells decreased from 85% to 75%. The degree of saturation increased from 82% to 83% due to liquids addition in the Retrofit

  19. Silicon microhole arrays architecture for stable and efficient photoelectrochemical cells using ionic liquids electrolytes

    Science.gov (United States)

    Shen, Xiaojuan; Chen, Ling; Li, Junnan; Zhao, Jie

    2016-06-01

    Silicon microhole arrays (SiMHs) structure is constructed and fabricated by a low-cost maskless anodic etching process, which is applied as the photoanode for the silicon photoelectrochemical (PEC) cells. The depths of silicon microhole arrays can be independently controlled by the etching time. The light-scattering properties are also investigated. Additionally, surface morphology analysis show that large hole diameters of SiMHs is very favourable for the full-filling of ionic liquids electrolyte. Therefore, better electrochemical contact as well as high ionic conductivity of the ionic liquids electrolyte renders the PEC SiMHs solar cells to exhibit more excellent performance. After optimization, the maximum PCE could be achieved at 4.04% for the SiMHs cell. The performance of the SiMHs cell is highly comparable to that of silicon nanowires cell. More importantly, the liquid-state electrolyte is confined in the unique microhole structure, which can obviously prevent the leakage of the ionic liquids electrolyte, resulting in much better long-term stability than the reference devices. These preliminary results validate the concept of interpenetrating networks with semiconductor structure/ILs junction to develop stable and efficient PEC cells.

  20. Dependence of image flicker on dielectric anisotropy of liquid crystal in a fringe field switching liquid crystal cell

    Science.gov (United States)

    Oh, Seung-Won; Baek, Jong-Min; Kim, Jung-Wook; Yoon, Tae-Hoon

    2016-09-01

    Two types of image flicker, which are caused by the flexoelectric effect of liquid crystals (LCs), are observed when a fringe-field switching (FFS) LC cell is driven by a low frequency electric field. Static image flicker, observed because of the transmittance difference between neighboring frames, has been reported previously. On the other hand, research on dynamic image flicker has been minimal until now. Dynamic image flicker is noticeable because of the brief transmittance drop when the sign of the applied voltage is reversed. We investigated the dependence of the image flicker in an FFS LC cell on dielectric anisotropy of the LCs in terms of both the static and dynamic flicker. Experimental results show that small dielectric anisotropy of the LC can help suppress not only the static but also dynamic flicker for positive LCs. We found that both the static and dynamic flicker in negative LCs is less evident than in positive LCs.

  1. Transcriptome Analysis of Spartina pectinata in Response to Freezing Stress.

    Science.gov (United States)

    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

  2. High-performance liquid-catalyst fuel cell for direct biomass-into-electricity conversion.

    Science.gov (United States)

    Liu, Wei; Mu, Wei; Deng, Yulin

    2014-12-01

    Herein, we report high-performance fuel cells that are catalyzed solely by polyoxometalate (POM) solution without any solid metal or metal oxide. The novel design of the liquid-catalyst fuel cells (LCFC) changes the traditional gas-solid-surface heterogeneous reactions to liquid-catalysis reactions. With this design, raw biomasses, such as cellulose, starch, and even grass or wood powders can be directly converted into electricity. The power densities of the fuel cell with switchgrass (dry powder) and bush allamanda (freshly collected) are 44 mW cm(-2) and 51 mW cm(-2) respectively. For the cellulose-based biomass fuel cell, the power density is almost 3000 times higher than that of cellulose-based microbial fuel cells. Unlike noble-metal catalysts, POMs are tolerant to most organic and inorganic contaminants. Therefore, almost any raw biomass can be used directly to produce electricity without prior purification. PMID:25283435

  3. Experimental analysis and modeling of ultrasound assisted freezing of potato spheres.

    Science.gov (United States)

    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. PMID:25776740

  4. Liquid Fluoride Salt Experimentation Using a Small Natural Circulation Cell

    Energy Technology Data Exchange (ETDEWEB)

    Yoder Jr, Graydon L [ORNL; Heatherly, Dennis Wayne [ORNL; Williams, David F [ORNL; Elkassabgi, Yousri M. [Texas A& M University, Kingsville; Caja, Joseph [Electrochemical Systems, Inc.; Caja, Mario [ORNL; Jordan, John [Texas A& M University, Kingsville; Salinas, Roberto [Texas A& M University, Kingsville

    2014-04-01

    A small molten fluoride salt experiment has been constructed and tested to develop experimental techniques for application in liquid fluoride salt systems. There were five major objectives in developing this test apparatus: Allow visual observation of the salt during testing (how can lighting be introduced, how can pictures be taken, what can be seen) Determine if IR photography can be used to examine components submerged in the salt Determine if the experimental configuration provides salt velocity sufficient for collection of corrosion data for future experimentation Determine if a laser Doppler velocimeter can be used to quantify salt velocities. Acquire natural circulation heat transfer data in fluoride salt at temperatures up to 700oC All of these objectives were successfully achieved during testing with the exception of the fourth: acquiring velocity data using the laser Doppler velocimeter. This paper describes the experiment and experimental techniques used, and presents data taken during natural circulation testing.

  5. Freeze-fracture study of Trichomonas vaginalis

    Directory of Open Access Journals (Sweden)

    Marlene Benchimol

    1990-12-01

    Full Text Available The freeze-fracture technique was used to analyse the organization of the plasma membrane, as well as membranes of cytoplasmic organelles, of the pathogenic protozoan Trichomonas vaginalis. Rosettes formed by 4 to 14 intramembranous particles were seen on the fracture faces of the membrane lining the anterior flagella as well as in fracture faces of the plasma membrane enclosing the anterior region of the protozoan and in cytoplasmic organelles. Special organization of the membrane particles were also seen in the region of association of the recurrent flagellum to the cell body.

  6. An experimental study of freezing of supercooled water droplet on solid surface

    Science.gov (United States)

    Alekseenko, S. V.; Mendig, C.; Schulz, M.; Sinapius, M.; Prykhodko, O. A.

    2016-05-01

    Results of experimental investigations of the freezing of immobile water droplet on an aluminum plate are presented. The process was studied with the aid of a high-speed photo camera. The freezing of supercooled water contained in the surface droplet proceeds in a few stages: (i) preliminary heating of water and nucleation of ice microcrystals, (ii) relatively fast formation of the ice-liquid system with a transition to the state of thermodynamic equilibrium near the freezing temperature, and (iii) slow process of complete freezing. The rate and duration of each stage and the time of delay between the moment of action upon the supercooled droplet and the onset of freezing are estimated. Processes of supercooled and nonsupercooled water solidification are compared.

  7. The Impact of Soil Freezing/Thawing Processes on Water and Energy Balances

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xia; SUN Shufen

    2011-01-01

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

  8. Freeze-in through portals

    CERN Document Server

    Blennow, Mattias; Zaldivar, Bryan

    2014-01-01

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

  9. Freeze Protection in Gas Holders

    DEFF Research Database (Denmark)

    Hjorth, Poul G.; Duursma, Gail

    In cold weather, the water seals of gasholders need protection from freez- ing to avoid compromising the seal. These holders have a large reservoir of “tank water” at the base which is below ground. At present freeze- protection is achieved by external heating of the seal water which...... is in a slotted channel called a cup. Electrical heating or circulation of heated tank water to the cup are examples of systems presently used. The tank water has a large thermal capacity and National Grid wishes to inves- tigate whether circulation of the tank water without external heating could provide...... sufficient energy input to avoid freezing. Only tanks in which the tank water is below ground are investigated in the report. The soil temperature under the reservoir at depth of 10m and lower is almost constant....

  10. Liquid Tin Anode Direct Coal Fuel Cell Final Program Report

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Thomas

    2012-01-26

    This SBIR program will result in improved LTA cell technology which is the fundamental building block of the Direct Coal ECL concept. As described below, ECL can make enormous efficiency and cost contributions to utility scale coal power. This program will improve LTA cells for small scale power generation. As described in the Commercialization section, there are important intermediate military and commercial markets for LTA generators that will provide an important bridge to the coal power application. The specific technical information from this program relating to YSZ electrolyte durability will be broadly applicable SOFC developers working on coal based SOFC generally. This is an area about which very little is currently known and will be critical for successfully applying fuel cells to coal power generation.

  11. Galvanic cell without liquid junction for potentiometric determination of copper.

    Science.gov (United States)

    Migdalski, Jan; Błaz, Teresa; Zrałka, Barbara; Lewenstam, Andrzej

    2007-07-01

    This paper describes potentiometric measurements in an integrated galvanic cell with both indicator and reference electrodes. Both electrodes are conducting polymer-based. The copper-sensitive indicator electrode is made by using poly(3,4-ethylenedioxythiophene) (PEDOT) doped with 2-(o-arsenophenylazo)-1,8-dihydroxynaphthalene-3,6-disulphonic sodium salt (Arsenazo-I) as the electroactive substance in the film, while the reference electrode is based on PEDOT doped by 2-morpholineoethanesulfonic acid (MES). It is shown that the galvanic cell can be used for determination of copper both in non-aqueous media (where all PVC-based membranes failed) and in the presence of chloride ions, which disturb the signal of conventional copper ion-selective electrodes with solid-state membranes. It is further shown that the titration of copper ions can be successfully monitored using the described electrochemical cell.

  12. Performance comparison of autothermal reforming for liquid hydrocarbons, gasoline and diesel for fuel cell applications

    Science.gov (United States)

    Kang, Inyong; Bae, Joongmyeon; Bae, Gyujong

    This paper discusses the reforming of liquid hydrocarbons to produce hydrogen for fuel cell applications, focusing on gasoline and diesel due to their high hydrogen density and well-established infrastructures. Gasoline and diesel are composed of numerous hydrocarbon species including paraffins, olefins, cycloparaffins, and aromatics. We have investigated the reforming characteristics of several representative liquid hydrocarbons. In the case of paraffin reforming, H 2 yield and reforming efficiency were close to thermodynamic equilibrium status (TES), although heavier hydrocarbons required slightly higher temperatures than lighter hydrocarbons. However, the conversion efficiency was much lower for aromatics than paraffins with similar carbon number. We have also investigated the reforming performance of simulated commercial diesel and gasoline using simple synthetic diesel and gasoline compositions. Reforming performances of our formulations were in good agreement with those of commercial fuels. In addition, the reforming of gas to liquid (GTL) resulted in high H 2 yield and reforming efficiency showing promise for possible fuel cell applications.

  13. 液晶盒的电容特性%Capacitance Characteristics of Liquid Crystal Cell

    Institute of Scientific and Technical Information of China (English)

    刘晓芳; 崔文静; 邢红玉; 叶文江; 张志东

    2012-01-01

    液晶盒外加一定的电压,会改变液晶分子的取向排列,这样液晶层的有效介电常数也会随之发生改变。如果把液晶盒看作一个电容器,其电容也会有所改变。本论文理论研究强锚泊混合排列向列相液晶盒的电容特性,基于液晶弹性理论和变分原理,理论推导液晶盒系统的平衡态方程及电容的解析表达式,通过Matlab软件数值模拟了此液晶盒的电容-电压曲线和指向矢分布曲线,并对其电容特性进行了分析。%The certain voltage applied to the liquid crystal can change the orientation of liquid crystal molecules, which results in the change of the effective dielectric constant. If the liquid crystal cell may be seen as a capacitor, the capacitance of this cell will also vary. In this paper, the capacitance characteristics of strong anchoring hybrid-aligned nematic liquid crystal cell are studied theoretically. Based on liquid crystal elasticity theory and variational principles, the equilibrium equations and the analytical expression of the capacitance of this cell are deduced theoretically. The capacitance-voltage curves and the distribution of director of this cell are simulated numerically by using the Matlab software, through which the capacitance characteristics of this cell is analyzed.

  14. Freeze-Etch of Emulsified Cake Batters During Baking

    OpenAIRE

    Cloke, J. D.; Gordon, J; Davis, E.A.

    1982-01-01

    Cryofixation, freeze-etch techniques were used to study the structure of cake batters made from a lean cake formulation before heating and after heating to temperatures up to l00-l02°C. Batters were prepared without added emulsifiers and with saturated and unsaturated monoglycerides replacing 5 and l 0% of the oil. Unsaturated monoglyceri des were more effective than saturated monoglycerides in dispersing oil droplets through the batter. Saturated monoglycerides formed liquid crystals during ...

  15. An elastoplastic model for the THM analysis of freezing soils

    OpenAIRE

    Satoshi,Nishimura; Gens Solé, Antonio; Olivella Pastallé, Sebastià; Jardine, Richard

    2009-01-01

    By employing a combination of ice pressure, liquid pressure and total stress as state variables, a new thermoplastic constitutive model has been developed that encompasses frozen and unfrozen behaviour within a unified effective-stress-based framework. It has been incorporated into a fully coupled thermo-hydro-mechanical (THM) finite element formulation that considers freezing and thawing in water-saturated soils and applied to a large-scale pipeline frost heave test. Peer Reviewed

  16. Liquid marbles for high-throughput biological screening of anchorage-dependent cells.

    Science.gov (United States)

    Oliveira, Nuno M; Correia, Clara R; Reis, Rui L; Mano, João F

    2015-01-28

    Stable liquid marbles (LM) are produced by coating liquid droplets with a hydrophobic powder. The used hydrophobic powder is produced by fluorosi-lanization of diatomaceous earth, used before to produce superhydrophobic structures. Here, the use of LM is proposed for high-throughput drug screening on anchorage-dependent cells. To provide the required cell adhesion sites inside the liquid environment of LM, surface-modified poly(l-lactic acid) microparticles are used. A simple method that takes advantage from LM appealing features is presented, such as the ability to inject liquid on LM without disrupting (self-healing ability), and to monitor color changes inside of LM. After promoting cell adhesion, a cytotoxic screening test is performed as a proof of concept. Fe(3+) is used as a model cytotoxic agent and is injected on LM. After incubation, AlamarBlue reagent is injected and used to assess the presence of viable cells, by monitoring color change from blue to red. Color intensity is measured by image processing and the analysis of pictures takes using an ordinary digital camera. The proposed method is fully validated in counterpoint to an MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carbo​xymethoxyphenyl)-2-(4-sulfophenyl)-2H-te​trazolium) colorimetric assay, a well-known method used for the cytotoxicity assessment.

  17. Investigating Processes of Nanocrystal Formation and Transformation via Liquid Cell TEM

    DEFF Research Database (Denmark)

    Nielsen, Michael H.; Li, Dongsheng; Zhang, Hengzhong;

    2014-01-01

    and spatial resolution of experimental techniques that can observe dynamic processes in a bulk solution. Here we report results from liquid cell transmission electron microscopy studies of nucleation and growth of Au, CaCO3, and iron oxide nanoparticles. We show how these in situ data can be used to obtain...

  18. Comparison of Diagnostic Cytomorphology of Atypical Squamous Cells in Liquid-Based Preparations and Conventional Smears

    OpenAIRE

    Lee, Jung Dal; Oh, Young-Ha; Lee, Seong Ok; Kim, Jong Yull

    2012-01-01

    Background The aims of this study were to compare the cytomorphologic features diagnostic of atypical squamous cells (ASC) in liquid-based preparations (LBPs) and conventional Pap (CP) smears and to cytomorphologically assess the performance of the Cell Scan 1500™ in cervical cytology practice. Methods Cervicovaginal smears were obtained from 938 women. Two smears were obtained simultaneously from each individual, one for an LBP and the other for a CP smear; the smears were independently exam...

  19. Giant panda (Ailuropoda melanoleuca) sperm morphometry and function after repeated freezing and thawing.

    Science.gov (United States)

    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 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. PMID:26268795

  20. Factors influencing the outcome of embryo freezing and Ihawing program

    Institute of Scientific and Technical Information of China (English)

    叶英辉; 金帆; 徐晨明; 邢兰凤

    2002-01-01

    Objective: To investigate the factors that might influence the sucess of an ernbryo freezing and thawing program.Method: The relationship between the pregnancy rate in 73 cycles of embryo freezing and thewing program and the following factors was analyzed;matermal age,E2 level at the time of HCG trigger,embryo storage time,number of thawed embryos transferred,presence of sponsoring embryos and intact embryos.And the suvival rate of thawed embryos with different morphology,cell stage and storage time was evaluated.Result:Transfer with three of more than three thawed embryos resulted in pragnancy rates of 38.5% and 35.7%,respectively.compared with 5.3% for transfer of fewer than three embryos.The presence of sponsoring embryos and intact embryos significantly incresses pregnancy rate in embryo freezing and thawing program .No other factor examined had any effect on pregnancy outcome.The survival rate of good morphology embryos was higher than poor ones,but was not influenced by cell stage and storage time.Conclusion:Embryo morphology before freezing , number of thawed embryos transferred and the presence of intact embryos are important to the outcome of embryo freezing and thawing program.

  1. Factors influencing the outcome of embryo freezing and thawing program

    Institute of Scientific and Technical Information of China (English)

    叶英辉; 金帆; 徐晨明; 邢兰凤

    2002-01-01

    Objective: To investigate the factors that might influence the succ ess of an embryo freezing and thawing program. Method: The relationship betwee n the pregnancy rate in 73 cycles of embryo freezing and thawing program and the following factors was analyzed: maternal age, E2 level at the time of HCG trigg er, embryo storage time, number of thawed embryos transferred, presence of spons oring embryos and intact embryos. And the survival rate of thawed embryos with d ifferent morphology, cell stage and storage time was evaluated. Result: Tra nsfer with three or more than three thawed embryos resulted in pregnancy rates o f 38.5% and 35.7%, respectively, compared with 5.3% for transfer of fewer th an t hree embryos. The presence of sponsoring embryos and intact embryos significantl y increases pregnancy rate in embryo freezing and thawing program. No other fact or examined had any effect on pregnancy outcome. The survival rate of good morph ology embryos was higher than poor ones, but was not influenced by cell stage an d storage time. Conclusion: Embryo morphology before freezing, number of thaw ed embryos transferred and the presence of intact embryos are important to the o utcome of embryo freezing and thawing program.

  2. Direct observations of dislocations in thermotropic smectics using freeze-fracture replication

    OpenAIRE

    Zasadzinski, Joseph A. N.

    1990-01-01

    Modern rapid-freezing methods followed by freeze-fracture replication techniques are ideally suited to allow the direct visualization of the three-dimensional structure and defects of thermotropic smectic and cholesteric liquid crystalline phases with resolution approaching molecular dimensions. Cholesterol nonanoate was quench frozen from near the smectic-cholesteric transition to reveal extensive, well defined smectic layers distorted by a high density of screw and edge dislocations. The sc...

  3. Response of Cytoskeleton of Murine Osteoblast Cultures to Two-step Freezing

    Institute of Scientific and Technical Information of China (English)

    Bao-Lin LIU; John McGRATH

    2005-01-01

    Understanding the ultrastructural response of cells to the freezing process is important for designing cryopreservation strategies for cells and tissues. The cellular structures of attached cells are targets of cryopreservation-induced damage. Specific fluorescence staining was used to assess the status of the actin filaments (F-actin) of murine osteoblasts attached to hydroxyapatite discs and plastic coverslips for a two-step freezing process. The F-actin of dead cells was depolymerized and distorted in the freezing process,whereas that of live cells had little change. The results suggest that the cytoskeleton may support the robustness of cells during cryopreservation. The present study helps to investigate the damage mechanism of attached cells during the freezing process.

  4. Numerical simulation of three-dimensional gas/liquid two-phase flow in a proton exchange membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    ZHUGE Weilin; ZHANG Yangjun; MING Pingwen; LAO Xingsheng; CHEN Xiao

    2007-01-01

    Investigation into the formation and transport of liquid water in proton exchange membrane fuel cells (PEMFCs) is the key to fuel cell water management.A threedimensional gas/liquid two-phase flow and heat transfer model is developed based on the multiphase mixture theory.The reactant gas flow,diffusion,and chemical reaction as well as the liquid water transport and phase change process are modeled.Numerical simulations on liquid water distribution and its effects on the performance of a PEMFC are conducted.Results show that liquid water distributes mostly in the cathode,and predicted cell performance decreases quickly at high current density due to the obstruction of liquid water to oxygen diffusion.The simulation results agree well with experimental data.

  5. Time dependence of immersion freezing

    Directory of Open Access Journals (Sweden)

    A. Welti

    2012-05-01

    Full Text Available The time dependence of immersion freezing was studied for temperatures between 236 K and 243 K. Droplets with single immersed, size-selected 400 nm and 800 nm kaolinite particles were produced at 300 K, cooled down to supercooled temperatures typical for mixed-phase cloud conditions, and the fraction of frozen droplets with increasing residence time was detected. To simulate the conditions of immersion freezing in mixed-phase clouds we used the Zurich Ice Nucleation Chamber (ZINC and its vertical extension, the Immersion Mode Cooling chAmber (IMCA. We observed that the frozen fraction of droplets increased with increasing residence time in the chamber. This suggests that there is a time dependence of immersion freezing and supports the importance of a stochastic component in the ice nucleation process. The rate at which droplets freeze was observed to decrease towards higher temperatures and smaller particle sizes. Comparison of the laboratory data with four different ice nucleation models, three based on classical nucleation theory with different representations of the particle surface properties and one singular, suggest that the classical, stochastic approach combined with a distribution of contact angles is able to reproduce the ice nucleation observed in these experiments most accurately. Using the models to calculate the increase in frozen fraction at typical mixed-phase cloud temperatures over an extended period of time, yields an equivalent effect of −1 K temperature shift and an increase in time scale by a factor of ~10.

  6. Probing Battery Chemistry with Liquid Cell Electron Energy Loss Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Unocic, Raymond R.; Baggetto, Loic; Veith, Gabriel M.; Aguiar, Jeffery A.; Unocic, Kinga A.; Sacci, Robert L.; Dudney, Nancy J.; More, Karren L.

    2015-11-25

    We demonstrate the ability to apply electron energy loss spectroscopy (EELS) to follow the chemistry and oxidation states of LiMn2O4 and Li4Ti5O12 battery electrodes within a battery solvent. The use and importance of in situ electrochemical cells coupled with a scanning/transmission electron microscope (S/TEM) has expanded and been applied to follow changes in battery chemistry during electrochemical cycling. Furthermore, we discuss experimental parameters that influence measurement sensitivity and provide a framework to apply this important analytical method to future in situ electrochemical studies.

  7. Fabrication of Monolithic Dye-Sensitized Solar Cell Using Ionic Liquid Electrolyte

    Directory of Open Access Journals (Sweden)

    Seigo Ito

    2012-01-01

    Full Text Available To improve the durability of dye-sensitized solar cells (DSCs, monolithic DSCs with ionic liquid electrolyte were studied. Deposited by screen printing, a carbon layer was successfully fabricated that did not crack or peel when annealing was employed beforehand. Optimized electrodes exhibited photovoltaic characteristics of 0.608 V open-circuit voltage, 6.90 cm−2 mA short-circuit current, and 0.491 fill factor, yielding 2.06% power conversion efficiency. The monolithic DSC using ionic liquid electrolyte was thermally durable and operated stably for 1000 h at 80°C.

  8. Tunable pretilt angles based on nanoparticles-doped planar liquid-crystal cells.

    Science.gov (United States)

    Jeng, Shie-Chang; Hwang, Shug-June; Yang, Chen-Yu

    2009-02-15

    The nanoparticles-induced vertical alignment technique was applied to generate variable liquid-crystal pretilt angles based on doping different concentrations of polyhedral oligomeric silsesquioxane (POSS) nanoparticles in the planar-aligned liquid crystal cells. Competition between the homogeneously aligned polyimide layer and POSS-induced spontaneous vertical alignment domain generated the variable pretilt angle. Experimental results demonstrated that the pretilt angle theta(p) is a function of the doped POSS concentration and can be controlled continuously over the range of 0 degrees

  9. Proton Conducting Polymer Membrane Using The Ionic Liquid 2-Hydroxyethylammonium Lactate For Ethanol Fuel Cells

    Science.gov (United States)

    Oliveira, L.; José, N. M.; Boaventura, J.; Iglesias, M.; Mattedi, S.

    2011-12-01

    In this work, there were developed a proton conducting polymer membrane using an ammonium based protic ionic liquid: 2-hydroxyethylamominum lactate for use in proton exchange fuel cells (PEMFC). This kind of ionic liquid has been proven to be biodegradable and they have potentially low toxicity besides low cost of preparation, simple synthesis and purification. The prepared membranes are hybrid organic-inorganic materials. The polymeric matrix is prepared with polydimethylsiloxane (PDMS) mixed with tetraethoxysilane (TEOS) in a ratio of 70/30% in weight. Then, the eletrolytical mixture containing sodium monododecylsulfate (SDS) and the ionic liquid was introduced in the lattice near the gel point, there were used different proportions of the eletrolyte from 5 to 30% in weight. The prepared membranes were characterized using infrared spectroscopy (FTIR), X-ray diffraction (DRX), termogravimetric analysis (TGA), scanning electronic microscopy (SEM) and conductivity and impedance measurements. The prepared materials are flexible, with good thermal and mechanical stability and with a great potential to be used as conducting membranes of fuel cells. The used mixture minimizes the lixiviation lost of the ionic liquid from the polymeric membrane and enhances the cell efficiency if compared with traditional synthetic membranes.

  10. Stability and distortions of liquid crystal order in a cell with a heterogeneous substrate

    Science.gov (United States)

    Zhang, Quan; Radzihovsky, Leo

    2010-05-01

    We study stability and distortions of liquid crystal nematic order in a cell with a random heterogeneous substrate. Modeling this system as a bulk xy model with quenched disorder confined to a surface, we find that nematic order is marginally unstable to such surface pinning. We compute the length scale beyond which nematic distortions become large and calculate orientational correlation functions using the functional renormalization-group and matching methods, finding universal logarithmic and double-logarithmic distortions in two and three dimensions, respectively. We extend these results to a finite-thickness liquid crystal cell with a second homogeneous substrate, detailing crossovers as a function of random pinning strength and cell thickness. We conclude with analysis of experimental signatures of these distortions in a conventional crossed-polarizer-analyzer light microscopy.

  11. Physical properties of smectic C liquid crystal cells

    CERN Document Server

    Dunn, P E

    1998-01-01

    key material parameters. Polarisation reversal current is used to measure both the spontaneous polarisation and an effective FLC switching viscosity. Monochromatic extinction angle measurements under applied d.c. fields are used to determine the cone and layer tilt angles, whilst a comparison of d.c. and a.c. extinction angle characteristics provides an estimate of the dielectric biaxiality. An automated measurement technique is used to determine FLC response time characteristics, which are described by a dynamic continuum theory switching model. In addition to optical techniques, x-ray diffraction is used to probe directly the smectic layer structure of several materials aligned in the surface stabilised chevron geometry. The layer structures adopted with anti-parallel alignment are also examined as a function of surface pretilt. Uniformly tilted layer structures are found to occur in test cells subjected to mechanical damage, and high electric fields are shown to produce quasi-bookshelf layer structures. Al...

  12. Polarization independent beam fanning using a multi-domain liquid crystal cell.

    Science.gov (United States)

    Ren, Hongwen; Wu, Shin-Tson

    2009-07-01

    Polarization independent beam fanning using a multi-domain liquid crystal (LC) cell is demonstrated experimentally. In the neighboring domains, the LC directors are aligned in orthogonal directions. To prove concepts, two hybrid-aligned LC cells with four and six domains were fabricated. Applying a voltage across the LC layer will change the phase difference between the neighboring domains. When the phase difference is 2mpi (m is an integer), the LC cell will not disturb the incident beam. However, if the phase shift is (2m + 1)pi, the outgoing beam will fan out into several beams; the number of fanout beams is equal to the domain number. PMID:19582068

  13. A Mathematical Model for Freeze-Drying

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on the experiments on freeze-drying carrot and potato slabs, the effects of some parameters, such as heating temperature and pressure on the freeze-drying process are examined. A simple model of freeze-drying is established to predict drying time and the mass variations of materials during the drying. The experimental results agree well with those calculated by the model.

  14. Asymmetric Melting and Freezing Kinetics in Silicon.

    OpenAIRE

    Aziz, Michael; Tsao, Jeff Y.; Thompson, Michael O.; Peercy, Paul S.

    1986-01-01

    We report measurements of the melting velocity of amorphous Si relative to that of (100) crystalline Si. These measurements permit the first severe experimental test of theories describing highly nonequilibrium freezing and melting. The results indicate that freezing in Si is inherently slower than melting; this asymmetry can be interpreted in terms of an entropy-related reduction in the freezing rate.

  15. 9 CFR 590.534 - Freezing facilities.

    Science.gov (United States)

    2010-01-01

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

  16. 9 CFR 590.536 - Freezing operations.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Freezing operations. 590.536 Section 590.536 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE EGG..., and Facility Requirements § 590.536 Freezing operations. (a) Freezing rooms shall be kept clean...

  17. EvoBot: An Open-Source, Modular Liquid Handling Robot for Nurturing Microbial Fuel Cells

    DEFF Research Database (Denmark)

    Faina, Andres; Nejatimoharrami, Farzad; Støy, Kasper;

    2016-01-01

    Liquid handling robots are rarely used in the domain of artificial life. In this field, transitory behaviours of non-equilibrium man-made systems are studied and need an automatic monitoring and logging of results. In addition, artificial life experiments are dynamic with frequent changes, which......-equilibrium conditions. In this paper, we describe the modular design of EvoBot, document its performance, and provide a novel example of an interactive experiment in artificial life, where the robot nurtures a microbial fuel cell based on its voltage output....... makes it difficult to apply conventional liquid handling robots as they are designed to automate a predefined task. In order to address these issues, we have developed an open source liquid handling robot, EvoBot. It uses a modular approach, which gives us the possibility to reconfigure the robot...

  18. Investigating design criteria to build a performing microbial fuel cell running on swine liquid manure

    Energy Technology Data Exchange (ETDEWEB)

    Martin, D.Y.; Hogue, R.; Dube, P.; Jeanne, T.; Levesque, A. [Inst. de recherche et de developpement en agroenvironnement Inc, Quebec City, PQ (Canada); Theriault, R.; Kaliaguine, S. [Laval Univ., Quebec City, PQ (Canada)

    2010-07-01

    This paper reported on a study that examined the bacterial and electro-chemical phenomena that takes place in a microbial fuel cell (MFC) operating on swine liquid manure as fuel. An MFC converts the available energy in a bioconvertible substrate directly into electricity while decreasing its chemical oxygen demand (COD). In this study, a first single chamber MFC operating on swine liquid manure was constructed based on a literature review. Various support media filling the anodic chamber were tested in an effort to optimize the surface area on which bacteria may develop according to the hypothesis that large bacteria concentration will improve energy production and reduce treatment time. Bacterial communities extracted from the selected support media were analyzed using molecular technologies such as DNA extraction, PCR amplification, denaturing gradient gel electrophoresis, cloning and sequencing. The analyses showed that only a few bacteria species coming from raw liquid manure were responsible for electrical activities.

  19. Deformation of freezing water droplets on a cold copper surface

    Institute of Scientific and Technical Information of China (English)

    WANG Jieteng; LIU Zhongliang; GOU Yujun; ZHANG Xinhua; CHENG Shuiyuan

    2006-01-01

    Freezing processes of water and peanut oil droplets on a cold surface are investigated in this paper. We observed during our experiments that the base surface of a water droplet that is in direct contact with the cold surface keeps its original shape, but the other part of the droplet shows an obvious growth along the direction normal to the base surface. One small protrusion appears on the top of the water droplet at the end of the freezing process. The experimental observations also show that no obvious shape change happens during the freezing of peanut oil droplets. It is postulated that the effects of surface tension and volume dilatation resulted from liquid-to-solid phase change cause the shape change and protrusions formation. Based on this postulation, a physical and mathematical model is developed. The results of the model of a water droplet's freezing process correspond with our experimental observations. The observed phenomenon that frost-growth speed on the protrusion is higher than that on the other part of the water droplet is also analyzed.

  20. Measurement of Freezing Point Depression of Selected Food Solutions

    Science.gov (United States)

    Murata, Satoshi; Tanaka, Fumihiko; Matsuoka, Takahisa

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

  1. Tuning and Freezing Disorder in Photonic Crystals using Percolation Lithography

    Science.gov (United States)

    Burgess, Ian B.; Abedzadeh, Navid; Kay, Theresa M.; Shneidman, Anna V.; Cranshaw, Derek J.; Lončar, Marko; Aizenberg, Joanna

    2016-01-01

    Although common in biological systems, synthetic self-assembly routes to complex 3D photonic structures with tailored degrees of disorder remain elusive. Here we show how liquids can be used to finely control disorder in porous 3D photonic crystals, leading to complex and hierarchical geometries. In these optofluidic crystals, dynamically tunable disorder is superimposed onto the periodic optical structure through partial wetting or evaporation. In both cases, macroscopic symmetry breaking is driven by subtle sub-wavelength variations in the pore geometry. These variations direct site-selective infiltration of liquids through capillary interactions. Incorporating cross-linkable resins into our liquids, we developed methods to freeze in place the filling patterns at arbitrary degrees of partial wetting and intermediate stages of drying. These percolation lithography techniques produced permanent photonic structures with adjustable disorder. By coupling strong changes in optical properties to subtle differences in fluid behavior, optofluidic crystals may also prove useful in rapid analysis of liquids.

  2. Electronic cigarette liquid increases inflammation and virus infection in primary human airway epithelial cells.

    Directory of Open Access Journals (Sweden)

    Qun Wu

    Full Text Available The use of electronic cigarettes (e-cigarettes is rapidly increasing in the United States, especially among young people since e-cigarettes have been perceived as a safer alternative to conventional tobacco cigarettes. However, the scientific evidence regarding the human health effects of e-cigarettes on the lung is extremely limited. The major goal of our current study is to determine if e-cigarette use alters human young subject airway epithelial functions such as inflammatory response and innate immune defense against respiratory viral (i.e., human rhinovirus, HRV infection.We examined the effects of e-cigarette liquid (e-liquid on pro-inflammatory cytokine (e.g., IL-6 production, HRV infection and host defense molecules (e.g., short palate, lung, and nasal epithelium clone 1, SPLUNC1 in primary human airway epithelial cells from young healthy non-smokers. Additionally, we examined the role of SPLUNC1 in lung defense against HRV infection using a SPLUNC1 knockout mouse model. We found that nicotine-free e-liquid promoted IL-6 production and HRV infection. Addition of nicotine into e-liquid further amplified the effects of nicotine-free e-liquid. Moreover, SPLUNC1 deficiency in mice significantly increased lung HRV loads. E-liquid inhibited SPLUNC1 expression in primary human airway epithelial cells. These findings strongly suggest the deleterious health effects of e-cigarettes in the airways of young people. Our data will guide future studies to evaluate the impact of e-cigarettes on lung health in human populations, and help inform the public about potential health risks of e-cigarettes.

  3. Cellulose and Their Characteristic Ice Nucleation Activity- Freezing on a Chip

    Science.gov (United States)

    Häusler, Thomas; Felgitsch, Laura; Grothe, Hinrich

    2016-04-01

    The influence of clouds on the Earth's climate system is well known (IPCC, 2013). Cloud microphysics determines for example cloud lifetime and precipitation properties. Clouds are cooling the climate system by reflecting incoming solar radiation and warm its surface by trapping outgoing infrared radiation (Baker and Peter, 2008). In all these processes, aerosol particles play a crucial role by acting as cloud condensation nuclei (CCN) for liquid droplets and as an ice nucleation particle (INP) for the formation of ice particles. Freezing processes at higher temperatures than -38°C occur heterogeneously (Pruppacher and Klett 1997). Therefore aerosol particles act like a catalyst, which reduces the energy barrier for nucleation. The nucleation mechanisms, especially the theory of functional sites are not entirely understood. It remains unclear which class of compound nucleates ice. Here we present a unique technique to perform drop- freezing experiments in a more efficient way. A self-made freezing- chip will be presented. Measurements done to proof the efficiency of our setup as well as advantages compared with other setups will be discussed. Furthermore we present a proxy for biological INPs, microcrystalline cellulose. Cellulose is the main component of herbal cell walls (about 50 wt%). It is a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose can contribute to the diverse spectrum of ice nucleation particles. We present results of the nucleation activity measurements of MCCs as well as the influence of concentration, preparation or chemical modification.

  4. Investigating the Mpemba Effect: When Hot Water Freezes Faster than Cold Water

    Science.gov (United States)

    Ibekwe, R. T.; Cullerne, J. P.

    2016-01-01

    Under certain conditions a body of hot liquid may cool faster and freeze before a body of colder liquid, a phenomenon known as the Mpemba Effect. An initial difference in temperature of 3.2 °C enabled warmer water to reach 0 °C in 14% less time than colder water. Convection currents in the liquid generate a temperature gradient that causes more…

  5. Perfluoro anion based binary and ternary ionic liquids as electrolytes for dye-sensitized solar cells

    Science.gov (United States)

    Lin, Hsi-Hsin; Peng, Jia-De; Suryanarayanan, V.; Velayutham, D.; Ho, Kuo-Chuan

    2016-04-01

    In this work, eight new ionic liquids (ILs) based on triethylammonium (TEA) or n-methylpiperidinium (NMP) cations and perfluoro carboxylate (PFC) anions having different carbon chain lengths are synthesized and their physico-chemical properties such as density, decomposition temperature, viscosity and conductivity are determined. Photovoltaic characteristics of dye-sensitized solar cells (DSSCs) with binary ionic liquids electrolytes, containing the mixture of the synthesized ILs and 1-methyl-3-propyl imidazolium iodide (PMII) (v/v = 35/65), are evaluated. Among the different ILs, solar cells containing NMP based ILs show higher VOC than that of TEA, whereas, higher JSC is noted for the DSSCs incorporated with the latter when compared to the former. Further, the photo-current of the DSSCs decreases with the increase of the carbon chain length of perfluoro carboxylate anionic group of ILs. The cell performance of the DSSC containing ternary ionic liquids-based electrolytes compose of NMP-2C/TEA-2C/PMII (v/v/v = 28/7/65) exhibits a JSC of 12.99 mA cm-2, a VOC of 639.0 mV, a FF of 0.72, and a cell efficiency of 6.01%. The extraordinary durability of the DSSC containing the above combination of electrolytes stored in dark at 50 °C is proved to be unfailing up to 1200 h.

  6. Cell deformation at the air-liquid interface induces Ca2+-dependent ATP release from lung epithelial cells.

    Science.gov (United States)

    Ramsingh, Ronaldo; Grygorczyk, Alexandra; Solecki, Anna; Cherkaoui, Lalla Siham; Berthiaume, Yves; Grygorczyk, Ryszard

    2011-04-01

    Extracellular nucleotides regulate mucociliary clearance in the airways and surfactant secretion in alveoli. Their release is exquisitely mechanosensitive and may be induced by stretch as well as airflow shear stress acting on lung epithelia. We hypothesized that, in addition, tension forces at the air-liquid interface (ALI) may contribute to mechanosensitive ATP release in the lungs. Local depletion of airway surface liquid, mucins, and surfactants, which normally protect epithelial surfaces, facilitate such release and trigger compensatory mucin and fluid secretion processes. In this study, human bronchial epithelial 16HBE14o(-) and alveolar A549 cells were subjected to tension forces at the ALI by passing an air bubble over the cell monolayer in a flow-through chamber, or by air exposure while tilting the cell culture dish. Such stimulation induced significant ATP release not involving cell lysis, as verified by ethidium bromide staining. Confocal fluorescence microscopy disclosed reversible cell deformation in the monolayer part in contact with the ALI. Fura 2 fluorescence imaging revealed transient intracellular Ca(2+) elevation evoked by the ALI, which did not entail nonspecific Ca(2+) influx from the extracellular space. ATP release was reduced by ∼40 to ∼90% from cells loaded with the Ca(2+) chelator BAPTA-AM and was completely abolished by N-ethylmalemide (1 mM). These experiments demonstrate that in close proximity to the ALI, surface tension forces are transmitted directly on cells, causing their mechanical deformation and Ca(2+)-dependent exocytotic ATP release. Such a signaling mechanism may contribute to the detection of local deficiency of airway surface liquid and surfactants on the lung surface. PMID:21239538

  7. Freeze and Thaw of CD4+CD25+Foxp3+ Regulatory T Cells Results in Loss of CD62L Expression and a Reduced Capacity to Protect against Graft-versus-Host Disease.

    Directory of Open Access Journals (Sweden)

    Mareike Florek

    Full Text Available The adoptive transfer of CD4+CD25+Foxp3+ regulatory T cells (Tregs in murine models of allogeneic hematopoietic cell transplantation (HCT has been shown to protect recipient mice from lethal acute graft-versus-host disease (GVHD and this approach is being actively investigated in human clinical trials. Here, we examined the effects of cryopreservation on Tregs. We found that freeze and thaw of murine and human Tregs is associated with reduced expression of L-selectin (CD62L, which was previously established to be an important factor that contributes to the in vivo protective effects of Tregs. Frozen and thawed murine Tregs showed a reduced capacity to bind to the CD62L binding partner MADCAM1 in vitro as well as an impaired homing to secondary lymphoid organs in vivo. Upon adoptive transfer frozen and thawed Tregs failed to protect against lethal GVHD compared with fresh Tregs in a murine model of allogeneic HCT across major histocompatibility barriers. In summary, the direct administration of adoptively transferred frozen and thawed Tregs adversely affects their immunosuppressive potential which is an important factor to consider in the clinical implementation of Treg immunotherapies.

  8. Fusion of liposomes with the plasma membrane of epithelial cells: Fate of incorporated lipids as followed by freeze fracture and autoradiography of plastic sections

    NARCIS (Netherlands)

    Knoll, G.; Burger, K.N.J.; Bron, R.; van Meer, G.; Verkleij, A.J.

    1988-01-01

    The fusion of liposomes with the plasma membrane of influenza virus-infected monolayers of an epithelial cell line, Madin-Darby canine kidney cells (van Meer et al., 1985. Biochemistry, 24: 3593-3602), has been analyzed by morphological techniques. The distribution of liposomal lipids over the apica

  9. Calculation of Effective Freezing Time in Lung Cancer Cryosurgery Based on Godunov Simulation

    Directory of Open Access Journals (Sweden)

    Т.G. Kotova

    2016-03-01

    Full Text Available There have been presented the results of lung cancer cryosurgery simulation using numerical solutions of enthalpy equation according to Godunov method. For the cryodestruction improvement purposes we successfully calculated the effective freezing time taking into account the evolution of an ice ball covering the tumor area. Geometrical transformation parameters of an ice ball have been measured by calculating the temperature distribution and the interface position in biological tissue. Mathematical cryosurgical procedures are described by heat transfer equations in solid and liquid phases. Numerical results for one-dimensional case were verified by comparing with exact solutions. In twodimensional modeling an effective cryotherapy time, which corresponds to freezing time of all tumor parts, was calculated as the area of forming ice balls covering all tumor region. The findings enable to set the effective time of a cryosurgical procedure in lung cancer. The knowledge of temperature distribution and interface position in biological tissue offers an opportunity to a cryosurgeon to finish the procedure within a certain time period to minimize the healthy tissue damage and destroy tumor cells to the maximum. Simulation application enables to schedule cryotherapy in lung cancer more effectively and to a good quality.

  10. AC Electric Field Enhances Cryopreservation Efficiency of Sprague-Dawley Rat Liver During a Slow Freezing Procedure.

    Science.gov (United States)

    Ma, Ya H; Qin, Guo F; Li, Jing; Ding, Gui R; Xu, Sheng L; Zhou, Yan; Guo, Guo Z

    2016-02-01

    Slow freezing coupled with an AC electric field (ACEF) has been demonstrated to miniaturize the ice crystals of a 0.9% (w/v) NaCl solution in a prior study. The aim of this study was to assess the effect of ACEF on Sprague-Dawley (SD) rat liver in vitro during the slow cooling procedure. SD rat liver exposed to an oscillating electric field was frozen in a programmed freezer initially down to -30°C at a cooling rate of -1°C/min and continuing down to -80°C at a cooling rate of -5°C/min. The cryovials were finally transferred into liquid nitrogen for 7 days. The frequency range was 0-20 MHz, and peak field strength was 1,000 V/m. For the sham and electric-exposed groups, the freezing solution consisted of 0%, 2.5%, 5.0%, 7.5%, or 10% (v/v) dimethyl sulfoxide (DMSO) Dulbecco's modified Eagles' medium culture solution, and fresh tissue was selected as the control group. The changes in cell survival rate, adenosine triphosphate (ATP) content, and morphology of fresh and frozen-thawed liver tissue were examined. Compared with the sham group with 5.0% DMSO, the result showed that slow freezing coupled with 2.45 MHz or 5 MHz ACEF significantly increased the relative survival rate by 43.27% and 26.31% (P membrane and some organelles (e.g., mitochondria) in the electric-exposed group appeared to be more intact according to the transmission electron microscopy images. The underlying mechanism might be that the ACEF affects the formation and growth of the ice crystallization, and thus inhibits cryoinjury. These results show that ACEF would provide an efficient method for cryopreservation banking with a low concentration of CPA during the slow freezing process. PMID:26828902

  11. Freeze Technology for Nuclear Applications - 13590

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  12. Feasibility study on the use of liquid crystal/dye cells for digital signage

    Science.gov (United States)

    Itaya, Shunsuke; Azumi, Nada Dianah B. M.; Ohta, Masamichi; Ozawa, Shintaro; Fujieda, Ichiro

    2016-03-01

    Elongated dye molecules orient themselves with surrounding liquid crystal molecules. We propose to incorporate such a guest-host cell in a screen of a projection display. This configuration might be applied for digital signage to be installed on building walls. Dual-mode operation is realized by the bias applied to the cell. In display-mode, the dye molecules are oriented in parallel to the substrate of the cell. When excited by ultra-violet light, photoluminescence (PL) is generated. Because it is mostly perpendicular to the long axis of the molecule, it exits the cell efficiently. In powerharvesting mode, they are oriented vertically. The PL generated by ambient light is directed to edge surfaces where solar cells are mounted. In experiment, we fabricated a cell with commonly-available materials (coumarin 6 and a nematic liquid crystal). Anti-parallel alignment condition was adopted. We recorded PL spectra from the cell for the two excitation conditions. First, the center of the cell was irradiated by a 1.69mW blue laser beam. Second, the whole cell was uniformly exposed to the light from a fluorescent lamp at illuminance of 800lx. From the measured spectra for these cases, the contrast of luminance is calculated to be 3.2 ×105 . This factor is improved to 5 7.5×105 by attaching a polarizer sheet on the cell surface. The optical power reaching its edge surfaces is measured and it roughly agrees with the prediction by a simple model neglecting self-absorption. Development of phosphor materials with a large Stokes shift is desired to boost performance of the proposed system.

  13. ON THE SATURATION BEHAVIOUR OF TWISTED NEMATIC LIQUID CRYSTAL CELLS WITH A NONZERO PRETILT ANGLE

    Institute of Scientific and Technical Information of China (English)

    ZHANG ZHI-DONG; YU HUI; LI LI

    2001-01-01

    Equations are obtained for the surface tilt angle and the twist angle of the director in a twisted nematic liquid crystal cell under a high magnetic field. Under a zero pretilt angle, the two equations reduce to those obtained by Sugimura et al.[2,3] This fact has also been demonstrated numerically. With finite field strength and nonzero pretilt angle, no saturation transition exists.

  14. Effects of freezing, freeze drying and convective drying on in vitro gastric digestion of apples.

    Science.gov (United States)

    Dalmau, Maria Esperanza; Bornhorst, Gail M; Eim, Valeria; Rosselló, Carmen; Simal, Susana

    2017-01-15

    The influence of processing (freezing at -196°C in liquid N2, FN sample; freeze-drying at -50°C and 30Pa, FD sample; and convective drying at 60°C and 2m/s, CD sample) on apple (var. Granny Smith) behavior during in vitro gastric digestion was investigated. Dried apples (FD and CD samples) were rehydrated prior to digestion. Changes in carbohydrate composition, moisture, soluble solids, acidity, total polyphenol content (TPC), and antioxidant activity (AA) of apple samples were measured at different times during digestion. Processing resulted in disruption of the cellular structure during digestion, as observed by scanning electron microscopy, light microscopy, and changes in carbohydrate composition. Moisture content increased (6-11% dmo), while soluble solids (55-78% dmo), acidity (44-72% dmo), total polyphenol content (30-61% dmo), and antioxidant activity (41-87%) decreased in all samples after digestion. Mathematical models (Weibull and exponential models) were used to better evaluate the influence of processing on apple behavior during gastric digestion. PMID:27542444

  15. Self-assembled polyelectrolyte nanorings observed by liquid-cell AFM

    Energy Technology Data Exchange (ETDEWEB)

    Menchaca, J-Luis [Instituto de Fisica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Flores, Hector [Facultad de Estomatologia, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico); Cuisinier, Frederic [INSERM U 595, Federation de Recherche Odontologiques, Universite Louis Pasteur, 11 rue Humann, 67085 Strasbourg Cedex (France); Perez, ElIas [Instituto de Fisica, Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, San Luis Potosi (Mexico)

    2004-06-09

    Self-assembled polyelectrolyte nanorings formed by polyelectrolytes are presented for the first time in this work. They are formed by poly(ethylenimine) (PEI) and poly(sodium 4-styrenesulfanate) (PSS) during the two first steps of the formation of the self-assembled polyelectrolyte films (SAPFs). These are formed on a negatively charged glass surface and observed by an in situ liquid-cell AFM technique, which has recently been introduced as an alternative technique to follow polyelectrolyte multilayer formation without drying effects (Menchaca et al 2003 Colloids Surf. A 222 185). Nanoring formation strongly depends on the preparation method and parameters such as polyelectrolyte filtration, air and CO{sub 2} presence during SAPFs formation and buffer solution. A necessary condition to obtain nanorings is that polyelectrolyte solutions have to be filtered prior to injection into the liquid-cell AFM. The outer diameter of nanorings can be varied from hundreds of nanometres to microns by changing these parameters. Nanorings are stable in the liquid cell for hours but they disappear on contact with air. Additionally, carbonate ions seem to be mainly responsible for the formation of this novel structure.

  16. Polymer Electrolyte Fuel Cells Membrane Hydration by Direct Liquid Water Contact

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.S.; Zawodzinski, C.; Gottesfeld, S.

    1998-11-01

    An effective means of providing direct liquid hydration of the membrane tends to improve performance particularly of cells with thicker membranes or at elevated temperatures. Supplying the water to the membrane from the anode flow-field through the anode backing via wicks would appear to have advantages over delivering the water through the thickness of the membrane with regards to the uniformity and stability of the supply and the use of off-the-shelf membranes or MEAs. In addition to improving cell performance, an important contribution of direct liquid hydration approaches may be that the overall fuel cell system becomes simpler and more effective. The next steps in the evolution of this approach are a demonstration of the effectiveness of this technique with larger active area cells as well as the implementation of an internal flow-field water reservoir (to eliminate the injection method). Scale-up to larger cell sizes and the use of separate water channels within the anode flow-field is described.

  17. Freezing effects of oil-in-water emulsions studied by sum-frequency scattering spectroscopy

    Science.gov (United States)

    Smit, W. J.; Smolentsev, N.; Versluis, J.; Roke, S.; Bakker, H. J.

    2016-07-01

    Temperature-dependent sum-frequency scattering spectroscopy is used to study the properties of hexadecane and dodecane oil droplets in water. The sum-frequency scattering spectra contain vibrational bands that correspond to the symmetric and antisymmetric CH stretching vibrations of the methylene (CH2) and methyl (CH3) groups of the alkane molecules. The relative amplitudes of the vibrational bands provide information on the surface structure and the shape of the oil droplets. We study the sum-frequency scattering spectra over a temperature range of -48 to 24 °C, including the freezing transitions of the water matrix and the oil droplets. Hexadecane oil droplets freeze at a higher temperature than the surrounding water, whereas dodecane oil droplets freeze at a lower temperature than the surrounding water. This allows us to independently study the freezing effect of oil and water on the surface structure of the oil droplets. In both cases, freezing leads to a change in the polarization dependencies that are valid in the case of the spherical-symmetric shapes that the oil droplets assume when both water and oil are liquid. We find that the freezing of water leads to a strong distortion of the liquid dodecane surface but has little effect on the surface of already solidified hexadecane. For completely frozen emulsions a further decrease in temperature is observed to lead to a further distortion of the surface of the solid oil particles, which might be caused by increasing hardness of the ice matrix encapsulating the particles.

  18. Comparative in vitro study of cholinium-based ionic liquids and deep eutectic solvents toward fish cell line.

    Science.gov (United States)

    Radošević, Kristina; Železnjak, Jelena; Cvjetko Bubalo, Marina; Radojčić Redovniković, Ivana; Slivac, Igor; Gaurina Srček, Višnja

    2016-09-01

    With the advent of ionic liquids, much was expected concerning their applicability as an alternative to organic solvents in the chemical technology and biotechnology fields. However, the most studied and commonly used ionic liquids based on imidazolium and pyridinium were found not to be as environmentally friendly as it was first expected. Therefore, a new generation of alternative solvents named natural ionic liquids and deep eutectic solvents, composed of natural and/or renewable compounds, have come into focus in recent years. Since the number of newly synthesized chemicals increases yearly, simple and reliable methods for their ecotoxicological assessment are necessary. Permanent fish cell lines can serve as a test system for the evaluation of a chemical's cytotoxicity. This paper presents research results on the cytotoxic effects on Channel Catfish Ovary (CCO) cell line induced by fifteen cholinium-based ionic liquids and deep eutectic solvents. Based on the decrease in cell viability, the most obvious toxic effect on CCO cells was caused by ionic liquid choline oxalate, while other solvents tested exhibited low cytotoxicity. Therefore, we can conclude that cholinium-based ionic liquids and deep eutectic solvents are comparatively less toxic to CCO cells than conventional ionic liquids. PMID:27179607

  19. Comparative in vitro study of cholinium-based ionic liquids and deep eutectic solvents toward fish cell line.

    Science.gov (United States)

    Radošević, Kristina; Železnjak, Jelena; Cvjetko Bubalo, Marina; Radojčić Redovniković, Ivana; Slivac, Igor; Gaurina Srček, Višnja

    2016-09-01

    With the advent of ionic liquids, much was expected concerning their applicability as an alternative to organic solvents in the chemical technology and biotechnology fields. However, the most studied and commonly used ionic liquids based on imidazolium and pyridinium were found not to be as environmentally friendly as it was first expected. Therefore, a new generation of alternative solvents named natural ionic liquids and deep eutectic solvents, composed of natural and/or renewable compounds, have come into focus in recent years. Since the number of newly synthesized chemicals increases yearly, simple and reliable methods for their ecotoxicological assessment are necessary. Permanent fish cell lines can serve as a test system for the evaluation of a chemical's cytotoxicity. This paper presents research results on the cytotoxic effects on Channel Catfish Ovary (CCO) cell line induced by fifteen cholinium-based ionic liquids and deep eutectic solvents. Based on the decrease in cell viability, the most obvious toxic effect on CCO cells was caused by ionic liquid choline oxalate, while other solvents tested exhibited low cytotoxicity. Therefore, we can conclude that cholinium-based ionic liquids and deep eutectic solvents are comparatively less toxic to CCO cells than conventional ionic liquids.

  20. Monitoring Ion Activities In and Around Cells Using Ion-Selective Liquid-Membrane Microelectrodes

    Directory of Open Access Journals (Sweden)

    Mark D. Parker

    2013-01-01

    Full Text Available Determining the effective concentration (i.e., activity of ions in and around living cells is important to our understanding of the contribution of those ions to cellular function. Moreover, monitoring changes in ion activities in and around cells is informative about the actions of the transporters and/or channels operating in the cell membrane. The activity of an ion can be measured using a glass microelectrode that includes in its tip a liquid-membrane doped with an ion-selective ionophore. Because these electrodes can be fabricated with tip diameters that are less than 1 μm, they can be used to impale single cells in order to monitor the activities of intracellular ions. This review summarizes the history, theory, and practice of ion-selective microelectrode use and brings together a number of classic and recent examples of their usefulness in the realm of physiological study.

  1. Advances of cell injury mechanism by freezing stress during processing of probiotic ice cream%冰淇淋中益生菌冷冻胁迫致菌体损伤机制研究进展

    Institute of Scientific and Technical Information of China (English)

    张健; 郑义; 朱金锦; 刘心怡; 杨贞耐

    2015-01-01

    冰淇淋是优良的益生菌载体,但其加工中的老化、凝冻和硬化等阶段性降温至冷冻的过程,会造成益生菌生理损伤,导致益生菌活力下降,功能性变差。近年,有关冰淇淋中冷冻胁迫致益生菌的损伤,冰淇淋中益生菌活性的保护,以及组学技术推动下的菌株损伤相关代谢研究取得了一定进展,为研究影响冰淇淋中益生菌存活能力、菌体细胞膜特性及代谢酶活性,明确冰淇淋基质中益生菌冷冻胁迫损伤的分子机制,建立冰淇淋加工和贮藏过程中益生菌的保护策略提供了可能,也为未来改善益生菌冰淇淋的功效和品质提供科学依据。%Ice cream is a favorable probiotic carrier. However, the viability and functions of probiotic strains tend to be lowered in ice cream processing, including aging, freezing and hardening. Recently, progress of researches about the probiotics injury, protection and their metabolic changes in ice cream based on omics techniques have been made, which provides the possibility to specify survival ability, membrane properties, and key molecules of metabolic enzyme activities of probiotics in ice cream. These studies also facilitate to uncover the molecular mechanism of cell injury caused by freezing stress during the processing of probiotic ice cream and establish protective strategies for probiotics during processing and storage of ice cream, and provide a scientific basis for the improvement of functionality and quality of such product.

  2. Contact freezing: a review of experimental studies

    Directory of Open Access Journals (Sweden)

    L. A. Ladino Moreno

    2013-10-01

    Full Text Available This manuscript compiles both theoretical and experimental information on contact freezing with the aim to better understand this potentially important but still not well quantified heterogeneous freezing mode. There is no complete theory that describes contact freezing and how the energy barrier has to be overcome to nucleate an ice crystal by contact freezing. Experiments on contact freezing conducted using the cold plate technique indicate that it can initiate ice formation at warmer temperatures than immersion freezing. Additionally, a qualitative difference in the freezing temperatures between contact and immersion freezing has been found using different instrumentation and different ice nuclei. There is a lack of data on collision rates in most of the reported data, which inhibits a quantitative calculation of the freezing efficiencies. Thus, new or modified instrumentation to study contact nucleation in the laboratory and in the field are needed to identify the conditions at which contact nucleation could occur in the atmosphere. Important questions concerning contact freezing and its potential role for ice cloud formation and climate are also summarized.

  3. Differential freezing resistance and photoprotection in C3 and C4 eudicots and grasses.

    Science.gov (United States)

    Liu, Mei-Zhen; Osborne, Colin P

    2013-05-01

    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

  4. Aqueous liquid feed organic fuel cell using solid polymer electrolyte membrane

    Science.gov (United States)

    Surampudi, Subbarao (Inventor); Narayanan, Sekharipuram R. (Inventor); Vamos, Eugene (Inventor); Frank, Harvey A. (Inventor); Halpert, Gerald (Inventor); Olah, George A. (Inventor); Prakash, G. K. Surya (Inventor)

    1997-01-01

    A liquid organic fuel cell is provided which employs a solid electrolyte membrane. An organic fuel, such as a methanol/water mixture, is circulated past an anode of a cell while oxygen or air is circulated past a cathode of the cell. The cell solid electrolyte membrane is preferably fabricated from Nafion.TM.. Additionally, a method for improving the performance of carbon electrode structures for use in organic fuel cells is provided wherein a high surface-area carbon particle/Teflon.TM.-binder structure is immersed within a Nafion.TM./methanol bath to impregnate the electrode with Nafion.TM.. A method for fabricating an anode for use in a organic fuel cell is described wherein metal alloys are deposited onto the electrode in an electro-deposition solution containing perfluorooctanesulfonic acid. A fuel additive containing perfluorooctanesulfonic acid for use with fuel cells employing a sulfuric acid electrolyte is also disclosed. New organic fuels, namely, trimethoxymethane, dimethoxymethane, and trioxane are also described for use with either conventional or improved fuel cells.

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

    Science.gov (United States)

    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.

  6. CHARACTERISTICS OF INTERACTIONS BETWEEN SOME TEXTURE PROPERTIES AND COMPOSITION OF CARRAGEENAN GELS AS A RESULT OF ITS DEFINED DIVERSIFIED FREEZING AND THAWING TREATMENT

    Directory of Open Access Journals (Sweden)

    Katarzyna Kozłowicz

    2013-06-01

    Full Text Available Model samples of carrageenan gels based on water, milk and juice were air-blast frozen and frozen by immersion in glycol and in liquid nitrogen. The gel freezing rate was determined on the basis of the kinetics of freezing. Carrageenan gel samples were characterized by evaluation of its thawing drip loss and hardness determined with compression and penetration tests. Freezing in liquid nitrogen ensured the highest freezing rates. Thawing drip loss of gels significantly depended on the carrageenan content, pH of the solution, freezing method and freezing rate. The resulting relationships are linear functions with high determination coefficients. The results of compression and penetration tests prove the significant effect of the carrageenan content and pH on gel hardness. The higher carrageenan content in a sample, the higher compression force and penetration of the gel. Gel freezing resulted in lower hardness. Freezing conditions had a significant effect on the properties tested. The correlation between compression forces and penetration depending on the carrageenan content and the freezing method was described using regression equations with high determination coefficients. Gels based on milk and juice with 2.2% carrageenan content are recommended for immersion freezing at rates above 5.0 cm·h-1.

  7. Freezing of testicular tissue as a minced suspension preserves sperm quality better than whole-biopsy freezing when glycerol is used as cryoprotectant.

    Science.gov (United States)

    Crabbé, E; Verheyen, G; Tournaye, H; Van Steirteghem, A

    1999-02-01

    Frozen-thawed testicular spermatozoa have been used successfully for ICSI, especially in cases of obstructive azoospermia with normal spermatogenesis. Fewer attempts, however, have been made to check whether these rather immature spermatozoa, in a different environment with several other cell types present, have cryobiological requirements other than those of ejaculated spermatozoa. This is the reason why the freezing protocols and cryoprotectants (glycerol) used for freezing testicular tissue are based on experience with semen freezing. This study aimed to assess whether cryosurvival and/or motility was influenced by freezing of testicular tissue either as an intact biopsy or as a shredded tissue suspension, when glycerol was used as cryoprotectant. Freezing of testicular tissue as a suspension preserved motility (type B + C) significantly better than freezing of whole biopsies (9.2% vs. 4.0%). Similar observations have been made for vitality (39.3% vs. 25.4%). Centrifugation on 50% Percoll in order to remove the cryoprotectant resulted in a huge loss of spermatozoa (or late spermatids) and should therefore be especially avoided in cases of testicular failure. On the basis of these observations, mincing of the testicular biopsies before freezing may be advocated. Testicular spermatozoa seem to be better preserved when frozen in suspension, at least when slowly permeating glycerol is used as a cryoprotectant. PMID:10068943

  8. Whole Cell Imprinting in Sol-Gel Thin Films for Bacterial Recognition in Liquids: Macromolecular Fingerprinting

    Directory of Open Access Journals (Sweden)

    Robert Armon

    2010-03-01

    Full Text Available Thin films of organically modified silica (ORMOSILS produced by a sol-gel method were imprinted with whole cells of a variety of microorganisms in order to develop an easy and specific probe to concentrate and specifically identify these microorganisms in liquids (e.g., water. Microorganisms with various morphology and outer surface components were imprinted into thin sol-gel films. Adsorption of target microorganism onto imprinted films was facilitated by these macromolecular fingerprints as revealed by various microscopical examinations (SEM, AFM, HSEM and CLSM. The imprinted films showed high selectivity toward each of test microorganisms with high adsorption affinity making them excellent candidates for rapid detection of microorganisms from liquids.

  9. DNA comet assay to identify different freezing temperatures of irradiated liver chicken

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Renato C.; Mozeika, Michel A.; Fanaro, Gustavo B.; Villavicencio, Anna L.C.H. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: renatocduarte@yahoo.com.br; Marchioni, Eric [Universite de Strasbourg, Illkirch (France). Faculte de Pharmacie. Lab. de Chimie Analytique et Sciences de l' Aliment

    2009-07-01

    The cold chain is a succession of steps which maintain the food at low temperature. The thawed food never be frozen again and the best solution being to consume it quickly to avoid the microorganism growth which causes decay and nutrients damage. One of most important point is that freezing process, unlike irradiation, do not destroy microorganisms, only inactive them as long as they remain in a frozen state. The Comet Assay is an original test used to detect irradiated foods that's recognize the DNA damage and can then be used to control the overall degradation of the food and in a certain extend to evaluate the damage caused by irradiation, different forms of freeze and storage time on liver chicken cells. Different freezing temperatures were used, deep freeze -196 deg C and slow freeze -10 deg C. Samples were irradiated in a {sup 60}Co irradiator with 1.5, 3.0 and 4.5 kGy radiation doses. Fast freezing technique induces a low percent of DNA degradation comparing to slow freezing technique. This procedure could be a good choose to chicken freezing processing. (author)

  10. Atmospheric freeze drying assisted by power ultrasound

    OpenAIRE

    Santacatalina Bonet, Juan Vicente; Carcel Carrión, Juan Andrés; García Pérez, José Vicente; Mulet Pons, Antonio; Simal, S.

    2012-01-01

    [EN] Atmospheric freeze drying (AFD) is considered an alternative to vacuum freeze drying to keep the quality of fresh product. AFD allows continuous drying reducing fix and operating costs, but presents, as main disadvantage, a long drying time required. The application of power ultrasound (US) can accelerate AFD process. The main objective of the present study was to evaluate the application of power ultrasound to improve atmospheric freeze drying of carrot. For that pur...

  11. Culturing of Human Nasal Epithelial Cells at the Air Liquid Interface

    Science.gov (United States)

    Müller, Loretta; Brighton, Luisa E.; Carson, Johnny L.; Fischer, William A.; Jaspers, Ilona

    2013-01-01

    In vitro models using human primary epithelial cells are essential in understanding key functions of the respiratory epithelium in the context of microbial infections or inhaled agents. Direct comparisons of cells obtained from diseased populations allow us to characterize different phenotypes and dissect the underlying mechanisms mediating changes in epithelial cell function. Culturing epithelial cells from the human tracheobronchial region has been well documented, but is limited by the availability of human lung tissue or invasiveness associated with obtaining the bronchial brushes biopsies. Nasal epithelial cells are obtained through much less invasive superficial nasal scrape biopsies and subjects can be biopsied multiple times with no significant side effects. Additionally, the nose is the entry point to the respiratory system and therefore one of the first sites to be exposed to any kind of air-borne stressor, such as microbial agents, pollutants, or allergens. Briefly, nasal epithelial cells obtained from human volunteers are expanded on coated tissue culture plates, and then transferred onto cell culture inserts. Upon reaching confluency, cells continue to be cultured at the air-liquid interface (ALI), for several weeks, which creates more physiologically relevant conditions. The ALI culture condition uses defined media leading to a differentiated epithelium that exhibits morphological and functional characteristics similar to the human nasal epithelium, with both ciliated and mucus producing cells. Tissue culture inserts with differentiated nasal epithelial cells can be manipulated in a variety of ways depending on the research questions (treatment with pharmacological agents, transduction with lentiviral vectors, exposure to gases, or infection with microbial agents) and analyzed for numerous different endpoints ranging from cellular and molecular pathways, functional changes, morphology, etc. In vitro models of differentiated human nasal epithelial

  12. Culturing of human nasal epithelial cells at the air liquid interface.

    Science.gov (United States)

    Müller, Loretta; Brighton, Luisa E; Carson, Johnny L; Fischer, William A; Jaspers, Ilona

    2013-10-08

    In vitro models using human primary epithelial cells are essential in understanding key functions of the respiratory epithelium in the context of microbial infections or inhaled agents. Direct comparisons of cells obtained from diseased populations allow us to characterize different phenotypes and dissect the underlying mechanisms mediating changes in epithelial cell function. Culturing epithelial cells from the human tracheobronchial region has been well documented, but is limited by the availability of human lung tissue or invasiveness associated with obtaining the bronchial brushes biopsies. Nasal epithelial cells are obtained through much less invasive superficial nasal scrape biopsies and subjects can be biopsied multiple times with no significant side effects. Additionally, the nose is the entry point to the respiratory system and therefore one of the first sites to be exposed to any kind of air-borne stressor, such as microbial agents, pollutants, or allergens. Briefly, nasal epithelial cells obtained from human volunteers are expanded on coated tissue culture plates, and then transferred onto cell culture inserts. Upon reaching confluency, cells continue to be cultured at the air-liquid interface (ALI), for several weeks, which creates more physiologically relevant conditions. The ALI culture condition uses defined media leading to a differentiated epithelium that exhibits morphological and functional characteristics similar to the human nasal epithelium, with both ciliated and mucus producing cells. Tissue culture inserts with differentiated nasal epithelial cells can be manipulated in a variety of ways depending on the research questions (treatment with pharmacological agents, transduction with lentiviral vectors, exposure to gases, or infection with microbial agents) and analyzed for numerous different endpoints ranging from cellular and molecular pathways, functional changes, morphology, etc. In vitro models of differentiated human nasal epithelial

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

    Science.gov (United States)

    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...

  14. A liquid film model of tetrakaidecahedral packing to account for the establishment of epidermal cell columns.

    Science.gov (United States)

    Menton, D N

    1976-05-01

    The possiblity that the organization of cells into columns in the mammalian epidermis may be a result of the close packing of these cells has been investigated in a model system involving the association of randomly produced soap bubbles into a stable froth. Upon floating to the surface of a liquid, soap bubbles have been found to spontaneously assemble into precise columns of interdigitating bubbles. The tetrakaidecahedral shape and the spatial configuration of these bubbles closely resemble those of stacked epidermal cells, although the columns of a froth were oriented at a 60degrees angle to their substratum rather than at right angles as occurs in the epidermal cell columns. These observations lend support to the theory that the organization of the cells in the epidermis into columns is due to the assumption of the keratocytes of a minimum surface-close packing array. Such an organizing mechanism would be independent of both positional control of the underlying mitoses and active guidance of the cells as they become superficially displaced within the epidermis. The observation that a high rate of cell turnover is incompatible with the epidermal column structure may be related to the finding that rapidly produced soap bubbles do not, at least initially, assemble into a columnar array. PMID:1270835

  15. Issues in Freeze Drying of Aqueous Solutions

    Institute of Scientific and Technical Information of China (English)

    王维; 陈墨; 陈国华

    2012-01-01

    Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze ding of aqueous solutions based on publications in the past few decades. The important issuesof the process are analyzed.

  16. When hot water freezes before cold

    CERN Document Server

    Katz, J I

    2006-01-01

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

  17. Modeling the chemical kinetics of atmospheric plasma for cell treatment in a liquid solution

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. Y.; Kang, S. K.; Lee, H. Wk. [Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Lee, H. W. [Medipl Corporation, Pohang 790-834 (Korea, Republic of); Kim, G. C. [Medipl Corporation, Pohang 790-834 (Korea, Republic of); Department of Oral Anatomy and Cell Biology, School of Dentistry, Pusan National University, Pusan 602-739 (Korea, Republic of); Lee, J. K. [Department of Electrical Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Medipl Corporation, Pohang 790-834 (Korea, Republic of)

    2012-07-15

    Low temperature atmospheric pressure plasmas have been known to be effective for living cell inactivation in a liquid solution but it is not clear yet which species are key factors for the cell treatment. Using a global model, we elucidate the processes through which pH level in the solution is changed from neutral to acidic after plasma exposure and key components with pH and air variation. First, pH level in a liquid solution is changed by He{sup +} and He(2{sup 1}S) radicals. Second, O{sub 3} density decreases as pH level in the solution decreases and air concentration decreases. It can be a method of removing O{sub 3} that causes chest pain and damages lung tissue when the density is very high. H{sub 2}O{sub 2}, HO{sub 2}, and NO radicals are found to be key factors for cell inactivation in the solution with pH and air variation.

  18. Sensitive detection of beryllium using a fiber optic liquid waveguide cell.

    Science.gov (United States)

    Deng, Gang; Wei, Lily; Collins, Greg E

    2003-05-28

    The metallochromic chelating agent, Chromazurol S, has been utilized in conjunction with a fiber optic liquid waveguide capillary cell to enable the sensitive detection of beryllium in solution (30 ng l(-1) detection limit) and following extraction from a contaminated plexiglas surface (0.5 ng cm(-2) detection limit). The addition of a cationic surfactant, cetylpyridinium chloride, to Chromazurol S at pH 10 in Tris-HCl buffer results in the formation of two bathochromic peaks in the visible spectrum following metal chelation by beryllium. The first absorbance band, at 515 nm, is intermediate in nature, permitting maximal sensitivity for low beryllium concentrations, but diminishing in intensity at concentrations above 100 mug l(-1). The second absorbance band, centered at 610 nm, dominates for beryllium concentrations of 100 mug l(-1) and above. Experimental conditions including pH, buffer type, additive surfactants, masking agents, and dye concentration were investigated in order to optimize detection sensitivity and selectivity. A fiber optic spectrometer is used with both a liquid waveguide capillary cell and 1 cm cuvette cell, to give a sensitive and broad dynamic range for beryllium detection that capitalizes on both beryllium metal chelate absorbance bands formed under these conditions.

  19. Effect of freezing and thawing on UMTRA covers

    International Nuclear Information System (INIS)

    The proposed US Environmental Protection Agency (EPA) groundwater standards (40 CFR 192) require that Uranium Mill Tailings Remedial Action (UMTRA) Project remedial action designs meet low numerical limits for contaminants contained in water or vapor exiting the embankments. To meet the standards, a cover of compacted fine-grained soil is placed over UMTRA Project embankments. One of the functions of this cover is to limit infiltration. The hydraulic conductivity of this infiltration barrier must be low in order to reduce seepage from the cell to the extent necessary to comply with the proposed EPA groundwater standards. Analyses of infiltration barriers covered with rock erosion protection show that the infiltration barriers may become saturated. Accordingly, it is necessary to assure that freezing and thawing of the infiltration barrier materials do not affect the performance of the embankment. A study has been conducted to determine if the hydraulic conductivity of fine-grained clayey soils used or proposed for use in radon/infiltration barriers is affected by repeated freezing and thawing cycles. In addition, a procedure for determining the depth of frost penetration has been developed. Laboratory freeze-thaw tests were undertaken in order to determine if the saturated hydraulic conductivity of clay soils used in UMTRA Project radon/infiltration barriers was affected. The results indicate that an increase of an order of magnitude or more in saturated hydraulic conductivity may occur during repeated freeze-thaw cycles

  20. Conducting liquid conveyer of plasma rings

    International Nuclear Information System (INIS)

    Current-carrying plasma rings can be conveyed in a cylindrical channel with a conducting liquid flow to which outer poloidal fields of the rings freeze. Fast tilting motion of the ring is stabilized when the liquid surface is set close to the ring within a critical distance. Effects of a resistive tube duct installed for the liquid are also examined. (author)

  1. Improvement of parameters of freezing medium and freezing protocol for bull sperm using two osmotic supports.

    NARCIS (Netherlands)

    Chaveiro, A.; Machado, A.L.; Frijters, A.; Engel, B.; Woelders, H.

    2006-01-01

    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 experimen

  2. Method for Making a Fuel Cell

    Science.gov (United States)

    Cable, Thomas L. (Inventor); Setlock, John A. (Inventor); Farmer, Serene C. (Inventor)

    2014-01-01

    The invention is a novel solid oxide fuel cell (SOFC) stack comprising individual bi-electrode supported fuel cells in which an electrolyte layer is supported between porous electrodes. The porous electrodes may be made from graded pore ceramic tape that has been created by the freeze cast method followed by freeze-drying. Each piece of graded pore tape later becomes a graded pore electrode scaffold that, subsequent to sintering, is made into either an anode or a cathode. The electrode scaffold comprising the anode includes a layer of liquid metal. The pores of the electrode scaffolds gradually increase in diameter as the layer extends away from the electrolyte layer. As a result of this diameter increase, any forces that would tend to pull the liquid metal away from the electrolyte are reduced while maintaining a diffusion path for the fuel. Advantageously, the fuel cell of the invention may utilize a hydrocarbon fuel without pre-processing to remove sulfur.

  3. In vitro cytotoxicity assessment of imidazolium ionic liquids: biological effects in fish Channel Catfish Ovary (CCO) cell line.

    Science.gov (United States)

    Radošević, Kristina; Cvjetko, Marina; Kopjar, Nevenka; Novak, Rudjer; Dumić, Jerka; Srček, Višnja Gaurina

    2013-06-01

    Increasing interest in the application of ionic liquids as green replacement for volatile organic solvents emphasized the need for the evaluation of their toxic effects at different biological systems in order to reduce the risk for human health and environment. To our knowledge, effects of imidazolium ionic liquids on cellular level of fish cell lines have not been studied yet. The cytotoxicity of imidazolium ionic liquids containing different anions and alkyl chain lengths as the substituent at the cation ring towards the fish CCO cell line was determined by WST-1 proliferation assay. Morphological alterations were examined by fluorescent microscopy using acridine orange/ethidium bromide staining and flow cytometry analysis was also performed. The results showed concentration-dependent cytotoxicity of ionic liquids in CCO cells, related to the type of anion and alkyl chain length, while EC50 values showed moderate to high cytotoxicity of tested imidazolium ionic liquids. Distinct morphological changes observed under fluorescence microscope and data obtained by flow cytometry suggest that the toxicity of imidazolium ionic liquids with longer alkyl chains could be related to necrosis. Results presented in here may be helpful for filling existing gaps of knowledge about ionic liquids toxicity and their impact on aquatic environment.

  4. Compatibility of lyotropic liquid crystals with viruses and mammalian cells that support the replication of viruses.

    Science.gov (United States)

    Cheng, Li-Lin; Luk, Yan-Yeung; Murphy, Christopher J; Israel, Barbara A; Abbott, Nicholas L

    2005-12-01

    We report a study that investigates the biocompatibility of materials that form lyotropic liquid crystals (LCs) with viruses and mammalian cells that support the replication of viruses. This study is focused on aqueous solutions of tetradecyldimethyl-amineoxide (C(14)AO) and decanol (D), or disodium cromoglycate (DSCG; C(23)H(14)O(11)Na(2)), which can form optically birefringent, liquid crystalline phases. The influence of these materials on the ability of vesicular stomatitis virus (VSV) to infect human epitheloid cervical carcinoma (HeLa) cells was examined by two approaches. First, VSV was dispersed in aqueous C(14)AO+ D or DSCG, and then HeLa cells were inoculated by contacting the cells with the aqueous C(14)AO + D or DSCG containing VSV. The infectivity of VSV to the HeLa cells was subsequently determined. Second, VSV was incubated in LC phases of either C(14)AO + D or DSCG for 4 h, and the concentration (titer) of infectious virus in the LC was determined by dilution into cell culture medium and subsequent inoculation of HeLa cells. Using these approaches, we found that the LC containing C(14)AO + D caused inactivation of virus as well as cell death. In contrast, we determined that VSV retained its infectivity in the presence of aqueous DSCG, and that greater than 74-82% of the HeLa cells survived contact with aqueous DSCG (depending on concentration of DSCG). Because VSV maintained its function (and we infer structure) in LCs formed from DSCG, we further explored the influence of the virus on the ordering of the LC. Whereas the LC formed from DSCG was uniformly aligned on surfaces prepared from self-assembled monolayers (SAMs) of HS(CH(2))(11)(OCH(2)CH(2))(4)OH on obliquely deposited films of gold in the absence of VSV, the introduction of 10(7)-10(8) infectious virus particles per milliliter caused the LC to assume a non-uniform orientation and a colorful appearance that was readily distinguished from the uniformly aligned LCs. Control experiments using

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

    Science.gov (United States)

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

    2016-09-01

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

  6. Collective constructions with micro-bricks. Application to the fabrication of liquid crystal micro-cells

    International Nuclear Information System (INIS)

    We present a method that makes it possible to deposit and bond micro-elements on an underlying device. In this manner, micro-constructions can be built by the addition of micro-bricks. The elements are fabricated on a flexible substrate covered with a release coating and are subsequently transferred and bonded onto the target device in a collective process. The process works on complex geometries and can accommodate surface defects, while maintaining a tightly controlled geometry. Application to the fabrication of liquid crystal micro-cells is presented. (paper)

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

    Science.gov (United States)

    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.

  8. -80℃非程控冷冻保存人外周血干细胞的效果观察%Cryopreservation of human peripheral blood stem cells by-80℃non rate-controlled freezing method

    Institute of Scientific and Technical Information of China (English)

    裴仁治; 岑东; 王奇军; 刘旭辉; 罗建平; 石兆玲

    2008-01-01

    Objective To investigate the cryopreservation of human peripheraI blood stern cells (PBSC)by-80℃non rate-controlled freezing method.Methods Forty-one samples of PBSC were obtained from 39 malignant tumor patients and 2 nornlal donors.PBSC in all malignant tumor patients were mobilized with special cherootherapy protocols combined with granulocyte colony-stimulating factor or granulocyte/monocyte colony-stimulating factor before collection.The obtained PBSC were mixed with same volume of cryoprotectant composed of 12 g/L hydroxyethyl starch,10% dimethylsulfoxide and 80 g/L human serunl albumin,and then eryopreserved in-80℃deep freeze refrigerator directly.Trypan blue viability and recovery rate of nucleated cells(NC),mononuclear cells(MNC),CD34+cells(CD34+),colony-forming unit-granulocyte macrophages (CFU-GM),burst forming unit-erythroid(BFU-E) were detected before and after cryopreservation in different periods.Results Having been cryopreserved from 1 month to 10 years in-80℃.there were no statistically significant differences in trypan blue viability,NC and MNC recovery rate(P>0.05).AIthough recovery rate of CD34+, CFU-M and BFU-E was decreased obviously after cryopreservation for 5-10 years(P<0.05),10-year recovery rate was 89.6%,85.1%and 83.7%,respectively.Thirty-four patients subject to corresponding pretreatment were transfused with-80℃ cryopreserved PBSC which had been stored for 13 to 35 days(mean 19 days)and hematological reconstitution was obtained successfully in 11 to 27 days (mean 14.7 days).Conclusion -80℃non rate-controlled freezing method is suitable to human PBSC long-term cryopreservation with the cryoproteetant composed of 60 g/L hydroxyethyl starch,5%dimethylsulfoxide and 40 g/L human serum albumin,and its cryopreservation effect is ideal%目的 探讨-80℃非程控冷冻保存人外周血干细胞(PBSC)的效果.方法 41份PBSC标本,39份采自恶性肿瘤患者,2份采自正常供者.对于恶性肿瘤患者,干细胞采集前

  9. Fabrication of uniformly cell-laden porous scaffolds using a gas-in-liquid templating technique.

    Science.gov (United States)

    Takei, Takayuki; Aokawa, Ryuta; Shigemitsu, Takamasa; Kawakami, Koei; Yoshida, Masahiro

    2015-11-01

    Design of porous scaffolds in tissue engineering field was challenging. Uniform immobilization of cells in the scaffolds with high porosity was essential for homogeneous tissue formation. The present study was aimed at fabricating uniformly cell-laden porous scaffolds with porosity >74% using the gas-in-liquid foam templating technique. To this end, we used gelatin, microbial transglutaminase and argon gas as a scaffold material, cross-linker of the protein and porogen of scaffold, respectively. We confirmed that a porosity of >74% could be achieved by increasing the gas volume delivered to a gelatin solution. Pore size in the scaffold could be controlled by stirring speed, stirring time and the pore size of the filter through which the gas passed. The foaming technique enabled us to uniformly immobilize a human hepatoblastoma cell line in scaffold. Engraftment efficiency of the cell line entrapped within the scaffold in nude mice was higher than that of cells in free-form. These results showed that the uniformly cell-laden porous scaffolds were promising for tissue engineering.

  10. A dose-controlled system for air-liquid interface cell exposure and application to zinc oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Ferron George A

    2009-12-01

    Full Text Available Abstract Background Engineered nanoparticles are becoming increasingly ubiquitous and their toxicological effects on human health, as well as on the ecosystem, have become a concern. Since initial contact with nanoparticles occurs at the epithelium in the lungs (or skin, or eyes, in vitro cell studies with nanoparticles require dose-controlled systems for delivery of nanoparticles to epithelial cells cultured at the air-liquid interface. Results A novel air-liquid interface cell exposure system (ALICE for nanoparticles in liquids is presented and validated. The ALICE generates a dense cloud of droplets with a vibrating membrane nebulizer and utilizes combined cloud settling and single particle sedimentation for fast (~10 min; entire exposure, repeatable (2. The cell-specific deposition efficiency is currently limited to 0.072 (7.2% for two commercially available 6-er transwell plates, but a deposition efficiency of up to 0.57 (57% is possible for better cell coverage of the exposure chamber. Dose-response measurements with ZnO nanoparticles (0.3-8.5 μg/cm2 showed significant differences in mRNA expression of pro-inflammatory (IL-8 and oxidative stress (HO-1 markers when comparing submerged and air-liquid interface exposures. Both exposure methods showed no cellular response below 1 μg/cm2 ZnO, which indicates that ZnO nanoparticles are not toxic at occupationally allowed exposure levels. Conclusion The ALICE is a useful tool for dose-controlled nanoparticle (or solute exposure of cells at the air-liquid interface. Significant differences between cellular response after ZnO nanoparticle exposure under submerged and air-liquid interface conditions suggest that pharmaceutical and toxicological studies with inhaled (nano-particles should be performed under the more realistic air-liquid interface, rather than submerged cell conditions.

  11. Process analysis of a liquid-feed direct methanol fuel cell system

    Science.gov (United States)

    Andrian, Stefanie v.; Meusinger, Josefin

    Recently, a greatly increasing interest in solid polymer electrolyte fuel cells (PEFC) for a range of applications has been observed. The direct methanol fuel cell (DMFC) based on a PEFC uses methanol directly for electric power generation and promises technical advantages, for example, for power trains. This study analyses the interaction between a DMFC stack fed with a liquid aqueous methanol solution and the peripheral system equipment. A simulation model of a DMFC system for mobile applications (from methanol to net electricity) is presented to calculate system efficiencies on the basis of thermodynamic engineering calculations. Based on the simulation calculations, useful operating requirements can be specified. To optimise the performance of DMFC systems, it is necessary to consider the operational characteristics of all the components required in the system. There are worldwide activities to improve the performance of a DMFC stack, which depends on numerous operating parameters. But it is not sufficient to optimise only the current/potential curves of the fuel cell without taking all the consequences for the system into consideration. The results of the computer simulation presented here emphasise the difficulties in improving fuel cell performance without decreasing system efficiency and describes the consequences for the system's operation conditions. Priorities are additionally set concerning the heat management of the fuel cell stack. In the case of liquid fuel supply, the water crossover through the membrane and the ensuing vapourisation at the cathode side impairs the thermal balance. Key operating parameters, which influence these effects, are pressure, temperature, air flow and methanol permeation rate.

  12. Basidiomycete cultures on perlite survive successfully repeated freezing and thawing in cryovials without subculturing.

    Science.gov (United States)

    Homolka, Ladislav; Lisá, Ludmila; Nerud, Frantisek

    2007-06-01

    Mycelial basidiomycete cultures on perlite in cryovials survived successfully three successive cycles of freezing, storage in liquid nitrogen (LN) and thawing without noticeable changes. This indicates that using perlite as a carrier for cryopreservation could in most cases overcome difficulties caused by interrupted supply of LN or electric power during the storage. Cultures on perlite can also be reused for successive inoculations.

  13. Redefining cooling rate in terms of ice front velocity and thermal gradient: first evidence of relevance to freezing injury of lymphocytes.

    Science.gov (United States)

    Beckmann, J; Körber, C; Rau, G; Hubel, A; Cravalho, E G

    1990-06-01

    A freezing process and the resulting injury or survival of biological cells is commonly characterized in terms of the cooling rate, B. Under certain circumstances, the cooling rate can be expressed as B = G.v, where G denotes the thermal gradient at the ice-liquid interface and v its velocity, respectively. To determine the influence of G and v on the morphology of the ice-liquid interface and on cell survival, a gradient freezing stage was designed. Flat capillaries could be pushed with constant velocity from a warm to a cold heat reservoir. With this setup both parameters, G and v, are independently adjustable and the resulting process of directional solidification can be observed dynamically in a light microscope. Human lymphocytes in phosphate-buffered saline with 10 vol% of dimethyl sulfoxide were used as biological test material. Viability was assessed by a membrane integrity test with fluorescein diacetate and ethidium bromide. All cells were cooled down to a final temperature of -196 degrees C and then rapidly thawed. The results obtained with this technique show that the viability determined after freezing and thawing with a certain cooling rate, B = G.v, may vary considerably depending on the imposed values of the thermal gradient, G, and the ice front velocity, v. In addition, the data seem to suggest that, first, the maximum viability which can be reached is governed by the cooling rate, and, second, this maximum for a given cooling rate could be achieved by establishing small temperature gradients and high interface velocities (about 30 degrees K/cm and 500 microns/sec, respectively, for the range of values of G and v tested). PMID:2379414

  14. Anhydrobiosis and freezing-tolerance: adaptations that facilitate the establishment of Panagrolaimus nematodes in polar habitats.

    Science.gov (United States)

    McGill, Lorraine M; Shannon, Adam J; Pisani, Davide; Félix, Marie-Anne; Ramløv, Hans; Dix, Ilona; Wharton, David A; Burnell, Ann M

    2015-01-01

    Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent "ecological fitting

  15. Anhydrobiosis and freezing-tolerance: adaptations that facilitate the establishment of Panagrolaimus nematodes in polar habitats.

    Directory of Open Access Journals (Sweden)

    Lorraine M McGill

    Full Text Available Anhydrobiotic animals can survive the loss of both free and bound water from their cells. While in this state they are also resistant to freezing. This physiology adapts anhydrobiotes to harsh environments and it aids their dispersal. Panagrolaimus davidi, a bacterial feeding anhydrobiotic nematode isolated from Ross Island Antarctica, can survive intracellular ice formation when fully hydrated. A capacity to survive freezing while fully hydrated has also been observed in some other Antarctic nematodes. We experimentally determined the anhydrobiotic and freezing-tolerance phenotypes of 24 Panagrolaimus strains from tropical, temperate, continental and polar habitats and we analysed their phylogenetic relationships. We found that several other Panagrolaimus isolates can also survive freezing when fully hydrated and that tissue extracts from these freezing-tolerant nematodes can inhibit the growth of ice crystals. We show that P. davidi belongs to a clade of anhydrobiotic and freezing-tolerant panagrolaimids containing strains from temperate and continental regions and that P. superbus, an early colonizer at Surtsey island, Iceland after its volcanic formation, is closely related to a species from Pennsylvania, USA. Ancestral state reconstructions show that anhydrobiosis evolved deep in the phylogeny of Panagrolaimus. The early-diverging Panagrolaimus lineages are strongly anhydrobiotic but weakly freezing-tolerant, suggesting that freezing tolerance is most likely a derived trait. The common ancestors of the davidi and the superbus clades were anhydrobiotic and also possessed robust freezing tolerance, along with a capacity to inhibit the growth and recrystallization of ice crystals. Unlike other endemic Antarctic nematodes, the life history traits of P. davidi do not show evidence of an evolved response to polar conditions. Thus we suggest that the colonization of Antarctica by P. davidi and of Surtsey by P. superbus may be examples of recent

  16. Viability of Two Freeze-dried Strains of Bifidobacterium Preparations at Various Temperatures during Prolonged Storage

    Institute of Scientific and Technical Information of China (English)

    DU Peng; DU Li-hui; HUO Gui-cheng

    2005-01-01

    Viability of bifidobacteria in freeze-dried probiotic products at various temperatures during prolonged storage was assessed. Bifidobacterium longum and Bifidobacterium infantis were freeze-dried. The freeze-dried preparations were stored at -18,4, and 20℃. Cell counts were enumerated using BS agar at 37℃ for 48 h under anaerobic conditions at 0, 45 and 120 days. Storage at 20℃ showed the greatest decline in the viability of bifidobacteria, whereas that at -18℃ showed the least decrease.

  17. Cooling and Freezing Behaviors of Aqueous Sodium Chloride Solution in a Closed Rectangular Container

    Science.gov (United States)

    Narumi, Akira; Kashiwagi, Takao; Nakane, Ichirou

    This paper investigates cooling and freezing behaviors of NaCl aqueous solution in a rectangular container equipped with horizontal partitions of micro porous film in order to determine the mechanisms of heat and mass transfer through cell wall for the purpose of freezing food. For comparison, experiments were performed using partitions of copper plate, no partition, and water. These processes were visualized and measured using real-time laser holographic interferometry. It was found that there was very little difference in the cooling process due to partitions, but that there were significant differences in freezing process when NaCl aqueous solution is used.

  18. Freezing Kinetics in Overcompressed Water

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-09-27

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

  19. Lipids differentially degraded during tissue freezing and thawing

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Plants cope with freezing and thawing by altering the lipid composition of their cell membranes. Such cellular responses go through three phases Successful test flight of an airship Researchers with the Balloon Aircraft Research Center (BARC) of the Academy of Opto-electronics, CAS, succeeded in their first test flight of an aeroboat with a flight altitude up to 1,000 meters and an effective payload of 20 kilograms in Shandong on 25 December, 2007.

  20. Freeze conditioning agents ease winter railcar unloading

    Energy Technology Data Exchange (ETDEWEB)

    Olson, G.E.

    1982-02-01

    A US midwest utility's freeze control programme is described. All coal is treated with a glycol-based freeze control agent. Some rail wagons were treated with a side release agent which stops coal sticking to the metal wagon. The use of calcium chloride or heat to thaw frozen coal is also discussed.

  1. Updating freeze: Aligning animal and human research

    NARCIS (Netherlands)

    Hagenaars, M.A.; Oitzl, M.S.; Roelofs, K.

    2014-01-01

    Freezing is widely used as the main outcome measure for fear in animal studies. Freezing is also getting attention more frequently in human stress research, as it is considered to play an important role in the development of psychopathology. Human models on defense behavior are largely based on anim

  2. Repeatability and randomness in heterogeneous freezing nucleation

    Directory of Open Access Journals (Sweden)

    G. Vali

    2008-08-01

    Full Text Available This study is aimed at clarifying the relative importance of the specific character of the nuclei and of the duration of supercooling in heterogeneous freezing nucleation by immersed impurities. Laboratory experiments were carried out in which sets of water drops underwent multiple cycles of freezing and melting. The drops contained suspended particles of mixtures of materials; the resulting freezing temperatures ranged from −6°C to −24°C. Rank correlation coefficients between observed freezing temperatures of the drops in successive runs were >0.9 with very high statistical significance, and thus provide strong support for the modified singular model of heterogeneous immersion freezing nucleation. For given drops, changes in freezing temperatures between cycles were relatively small (<1°C for the majority of the events. These frequent small fluctuations in freezing temperatures are interpreted as reflections of the random nature of embryo growth and are associated with a nucleation rate that is a function of a temperature difference from the characteristic temperatures of nuclei. About a sixth of the changes were larger, up to ±5°C, and exhibited some systematic patterns. These are thought to arise from alterations of the nuclei, some being permanent and some transitory. The results are used to suggest ways of describing ice initiation in cloud models that account for both the temperature and the time dependence of freezing nucleation.

  3. Repeatability and randomness in heterogeneous freezing nucleation

    Directory of Open Access Journals (Sweden)

    G. Vali

    2008-02-01

    Full Text Available This study is aimed at clarifying the relative importance of the specific character of the nuclei and of the duration of supercooling in heterogeneous freezing nucleation by immersed impurities. Laboratory experiments were carried out in which sets of water drops underwent multiple cycles of freezing and melting. The drops contained suspended particles of mixtures of materials; the resulting freezing temperatures ranged from −6°C to −24°C. Rank correlation coefficients between observed freezing temperatures of the drops in successive runs were >0.9 with very high statistical significance, and thus provide strong support for the modified singular model of heterogeneous immersion freezing nucleation. For given drops, changes in freezing temperatures between cycles were relatively small (<1°C for the majority of the events. These frequent small fluctuations in freezing temperatures are interpreted as reflections of the random nature of embryo growth and are associated with a nucleation rate that is a function of a temperature difference from the characteristic temperatures of nuclei. About a sixth of the changes were larger, up to ±5°C, and exhibited some systematic patterns. These are thought to arise from alterations of the nuclei, some being permanent and some transitory. The results are used to suggest ways of describing ice initiation in cloud models that account for both the temperature and the time dependence of freezing nucleation.

  4. Two beam energy exchange in hybrid liquid crystal cells with photorefractive field controlled boundary conditions

    Science.gov (United States)

    Reshetnyak, V. Yu.; Pinkevych, I. P.; Subota, S. I.; Evans, D. R.

    2016-09-01

    We develop a theory describing energy gain when two light beams intersect in a hybrid nematic liquid crystal (LC) cell with photorefractive crystalline substrates. A periodic space-charge field induced by interfering light beams in the photorefractive substrates penetrates into the LC layer and reorients the director. We account for two main mechanisms of the LC director reorientation: the interaction of the photorefractive field with the LC flexopolarization and the director easy axis at the cell boundaries. It is shown that the resulting director grating is a sum of two in-phase gratings: the flexoelectric effect driven grating and the boundary-driven grating. Each light beam diffracts from the induced gratings leading to an energy exchange between beams. We evaluate the signal beam gain coefficient and analyze its dependence on the director anchoring energy and the magnitude of the director easy axis modulation.

  5. A Janus-paper PDMS platform for air–liquid interface cell culture applications

    International Nuclear Information System (INIS)

    A commercially available Janus paper with one hydrophobic (polyethylene-coated) face and a hygroscopic/hydrophilic one is irreversibly bonded to a polydimethylsiloxane (PDMS) substrate incorporating microfluidic channels via corona discharge surface treatment. The bond strength between the polymer-coated side and PDMS is characterized as a function of corona treatment time and annealing temperature/time. A maximum strength of 392 kPa is obtained with a 2 min corona treatment followed by 60 min of annealing at 120 °C. The water contact angle of the corona-treated polymer side decreases with increased discharge duration from 98° to 22°. The hygroscopic/hydrophilic side is seeded with human lung fibroblast cells encapsulated in a methacrylated gelatin (GelMA) hydrogel to show the potential of this technology for nutrient and chemical delivery in an air–liquid interface cell culture. (paper)

  6. Immune cell activation from multivalent interactions with liquid-crystalline polycation-DNA complexes

    Science.gov (United States)

    Schmidt, Nathan; Jin, Fan; Lande, Roberto; Curk, Tine; Xian, Wujing; Frasca, Loredana; Dobnikar, Jure; Frenkel, Daan; Gilliet, Michel; Wong, Gerard

    2014-03-01

    Microbial DNA can trigger type I interferon (IFN) production in plasmacytoid cells (pDCs) by binding to endosomal toll-like receptor 9 (TLR9). TLR9 in pDCs do not normally respond to self-DNA, but in certain autoimmune diseases self-DNA can complex with the polycationic antimicrobial peptide LL37 into condensed structures which allow DNA to access endosomal compartments and stimulate TLR9 in pDCs. We use x-ray studies and cell measurements of IFN secretion by pDCs to show that a broad range of polycation-DNA complexes stimulate pDCs and elucidate the criterion for high IFN production. Furthermore, we show via experiments and computer simulations that the distinguishing factor for why certain complexes activate pDCs while others do not is the self-assembled structure of the liquid-crystalline polycation-DNA complex.

  7. Bioinspired Design: Magnetic Freeze Casting

    Science.gov (United States)

    Porter, Michael Martin

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

  8. Freeze concentration of lime juice

    Directory of Open Access Journals (Sweden)

    Ampawan Tansakul

    2008-11-01

    Full Text Available The main objective of this research was to study the effects of processing conditions, i.e. cooling medium temperature (-6, -12 and -18C and scraper blade rotational speed (50, 100 and 150 rpm on the freeze concentration of lime juice. The initial soluble solid content of lime juice was 7.6 Brix. Results showed that soluble solid content of lime juice increased as cooling medium temperature decreased while scraper blade rotational speed increased. It was also found that the processing condition with -18˚C cooling medium temperature and 150 rpm rotational speed of the scraper blade was the best among all studied conditions, although the loss of the soluble solids with ice crystals during ice separation was relatively high at 35%.

  9. Impregnation of leather during "freeze-drying"

    DEFF Research Database (Denmark)

    Storch, Mikkel; Vestergaard Poulsen Sommer, Dorte; Hovmand, Ida;

    2016-01-01

    Freeze-drying is a recognized method for the preservation of waterlogged objects. Naturally, freeze-drying has also been used for waterlogged archaeological leather often after treatment with Na2.EDTA and impregnation with PEG; but the treated leather sometimes suffers from “excessive drying......” becoming too stiff and brittle. The aim of this study was to examine the effect of a conventional freeze-drying method against an alternative freeze-drying method that preserves the natural moisture content of the leather. Both new and archaeological waterlogged leather were included in the study...... and the leather samples were treated in one of four ways: pre-treatment with Na2EDTA, impregnation with PEG 400, pre-treatment with Na2EDTA followed by impregnation with PEG 400 as well as no treatment. After the treatments, the leather samples were freeze-dried either by the conventional or by the alternative...

  10. Magneto-responsive liquid crystalline elastomer nanocomposites as potential candidates for dynamic cell culture substrates.

    Science.gov (United States)

    Herrera-Posada, Stephany; Mora-Navarro, Camilo; Ortiz-Bermudez, Patricia; Torres-Lugo, Madeline; McElhinny, Kyle M; Evans, Paul G; Calcagno, Barbara O; Acevedo, Aldo

    2016-08-01

    Recently, liquid crystalline elastomers (LCEs) have been proposed as active substrates for cell culture due to their potential to attach and orient cells, and impose dynamic mechanical signals through the application of external stimuli. In this report, the preparation of anisotropic and oriented nematic magnetic-sensitized LCEs with iron oxide nanoparticles, and the evaluation of the effect of particle addition at low concentrations on the resultant structural, thermal, thermo-mechanical, and mechanical properties is presented. Phase transformations produced by heating in alternating magnetic fields were investigated in LCEs in contact with air, water, and a common liquid cell culture medium was also evaluated. The inclusion of nanoparticles into the elastomers displaced the nematic-to-isotropic phase transition, without affecting the nematic structure as evidenced by similar values of the order parameter, while reducing the maximum thermomechanical deformations. Remote and reversible deformations of the magnetic LCEs were achieved through the application of alternating magnetic fields, which induces the nematic-isotropic phase transition through nanoparticle heat generation. Formulation parameters can be modified to allow for remote actuation at values closer to the human physiological temperature range and within the range of deformations that can affect the cellular behavior of fibroblasts. Finally, a collagen surface treatment was performed to improve compatibility with NIH-3T3 fibroblast cultures, which enabled the attachment and proliferation of fibroblasts on substrates with and without magnetic particles under quiescent conditions. The LCEs developed in this work, which are able to deform and experience stress changes by remote contact-less magnetic stimulation, may allow for further studies on the effect of substrate morphology changes and dynamic mechanical properties during in vitro cell culture. PMID:27157764

  11. Magneto-responsive liquid crystalline elastomer nanocomposites as potential candidates for dynamic cell culture substrates.

    Science.gov (United States)

    Herrera-Posada, Stephany; Mora-Navarro, Camilo; Ortiz-Bermudez, Patricia; Torres-Lugo, Madeline; McElhinny, Kyle M; Evans, Paul G; Calcagno, Barbara O; Acevedo, Aldo

    2016-08-01

    Recently, liquid crystalline elastomers (LCEs) have been proposed as active substrates for cell culture due to their potential to attach and orient cells, and impose dynamic mechanical signals through the application of external stimuli. In this report, the preparation of anisotropic and oriented nematic magnetic-sensitized LCEs with iron oxide nanoparticles, and the evaluation of the effect of particle addition at low concentrations on the resultant structural, thermal, thermo-mechanical, and mechanical properties is presented. Phase transformations produced by heating in alternating magnetic fields were investigated in LCEs in contact with air, water, and a common liquid cell culture medium was also evaluated. The inclusion of nanoparticles into the elastomers displaced the nematic-to-isotropic phase transition, without affecting the nematic structure as evidenced by similar values of the order parameter, while reducing the maximum thermomechanical deformations. Remote and reversible deformations of the magnetic LCEs were achieved through the application of alternating magnetic fields, which induces the nematic-isotropic phase transition through nanoparticle heat generation. Formulation parameters can be modified to allow for remote actuation at values closer to the human physiological temperature range and within the range of deformations that can affect the cellular behavior of fibroblasts. Finally, a collagen surface treatment was performed to improve compatibility with NIH-3T3 fibroblast cultures, which enabled the attachment and proliferation of fibroblasts on substrates with and without magnetic particles under quiescent conditions. The LCEs developed in this work, which are able to deform and experience stress changes by remote contact-less magnetic stimulation, may allow for further studies on the effect of substrate morphology changes and dynamic mechanical properties during in vitro cell culture.

  12. Food freezing with simultaneous surface dehydration: approximate prediction of freezing time

    Energy Technology Data Exchange (ETDEWEB)

    Campanone, Laura A.; Salvadori, Viviana O.; Mascheroni, Rodolfo H. [Centro de Investigacion Desarollo en Criotecnologia de Alimentos (CIDCA), Facultad de Ciencias Exactas, La Plata (Argentina); MODIAL, Facultad de Ingenieria, La Plata (Argentina)

    2005-03-01

    Freezing of unpackaged foods induces mass transfer in the form of surface ice sublimation, which in turn modifies heat transfer conditions. At present there are no simplified methods for predicting freezing times when surface dehydration occurs. This paper uses a previously developed model for the simulation of simultaneous heat and mass transfer during food freezing and storage to generate a complete set of predicted freezing times when dehydration occurs. Based on these data a simplified analytical method for the prediction of freezing time during freezing of unpackaged frozen foods was developed. The method accounts for product characteristics (shape, size and composition) and operating conditions (initial and refrigerant temperature, heat transfer coefficient, relative humidity). The prediction equation is very simple and results of its use - simulating usual freezing conditions for different products - shows very good accuracy when tested against the previously cited numerical model and all the available experimental data. (Author)

  13. Kinetic of Cryogenic Freezing of Seeds of Physic Nut (Jatropha curcas L.

    Directory of Open Access Journals (Sweden)

    Míriam Goldfarb

    2010-04-01

    Full Text Available The physic nut is an oils species, the oil extracted of the seeds has been used for biodiesel production. The cryoconservation consists of an option of storage of the seeds this species, cryogenic temperatures will to provide the reduction of the metabolism, resulting in the conservation. The objectives of this work was to determine the curve of freezing of the seeds in the cryogenic temperatures of -170ºC (nitrogen vapor and -196ºC (liquid nitrogen. The seeds with water content of 8% b.u., were exposed the cryogenic temperatures, were made evalutions in intervals of 5 seconds until reach the temperature of equilibrium. The results were for the temperature of -170ºC, the time to reach the temperature of equilibrium was 220 seconds and for the temperature of -196ºC, the time to occur the freezing was 200 seconds. About thermal diffusivity of seeds at -170ºC was 2,10443 x 10-3 mm2.s-1 and when were immersed in liquid nitrogen, the thermal diffusivity was 3,25787 x 10-3 mm2.s-1. The freezing curves were exponential and the three freezing phases were not distinguished. Conclusion that: as much bigger is the thermal gradient that the seeds were exposed, bigger was the values of the freezing speed and thermal diffusivity.

  14. A non-perturbative approach to freezing of superfuid 4He in density functional theory

    Science.gov (United States)

    Minoguchi, T.; Galli, De; Rossi, M.; Yoshimori, A.

    2012-12-01

    Freezing of various classical liquids is successfully described by density functional theory (DFT). On the other hand, so far no report has been published that DFT describes the freezing of superfuid 4He correctly. In fact, DFT gives too stable solid phase and the superfuid phase does not exist at finite positive pressures within a second order perturbation. In this paper we try a non-perturbative version of DFT, that is modified weighted density approximation (MWDA) to go beyond second order perturbation for the freezing of superfuid 4He. Via an exact zero temperature quantum Monte-Carlo (QMC) method we have computed the equation of state and the compressibility of superfuid 4He. By utilizing a recently introduced analytic continuation method (the GIFT method), we have obtained also density response functions at different densities from QMC imaginary time correlation functions. Contrary to second order perturbation, by employing these QMC data as DFT input we find a too stable superfuid phase, preventing freezing around the experimentally observed freezing pressure. We find the same pathological behavior by using another model energy functional of superfuid 4He (Orsay-Trento model). We conclude that the straightforward MWDA calculation gives such a poor result when liquid-gas transition is present.

  15. Electro-active hybrid actuators based on freeze-dried bacterial cellulose and PEDOT:PSS

    Science.gov (United States)

    Kim, Si-Seup; Jeon, Jin-Han; Kee, Chang-Doo; Oh, Il-Kwon

    2013-08-01

    We report a high-performance electro-active hybrid actuator based on freeze-dried bacterial cellulose and conducting polymer electrodes. The freeze-dried bacterial cellulose, which has a sponge form, can absorb a much greater amount of ionic liquid, which is a prerequisite for dry-type and high-performance electro-active polymers. In addition, the poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting layers are deposited on the top and bottom surfaces of the freeze-dried bacterial cellulose using a simple dipping and drying method. The results show that the freeze-dried bacterial cellulose actuator with conducting polymer electrodes has a much larger tip displacement under electrical stimuli than pure bacterial cellulose actuators with metallic electrodes. The large bending displacement of the freeze-dried bacterial cellulose actuator under low input voltage is due to the synergistic effects of the ion migration of the dissociated ionic liquids inside the bacterial cellulose and the electrochemical doping processes of the PEDOT:PSS electrode layers.

  16. Evaluation of E-Cigarette Liquid Vapor and Mainstream Cigarette Smoke after Direct Exposure of Primary Human Bronchial Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Stefanie Scheffler

    2015-04-01

    Full Text Available E-cigarettes are emerging products, often described as “reduced-risk” nicotine products or alternatives to combustible cigarettes. Many smokers switch to e-cigarettes to quit or significantly reduce smoking. However, no regulations for e-cigarettes are currently into force, so that the quality and safety of e-liquids is not necessarily guaranteed. We exposed primary human bronchial epithelial cells of two different donors to vapor of e-cigarette liquid with or without nicotine, vapor of the carrier substances propylene glycol and glycerol as well as to mainstream smoke of K3R4F research cigarettes. The exposure was done in a CULTEX® RFS compact  module, allowing the exposure of the cells at the air-liquid interface. 24 h post-exposure, cell viability and oxidative stress levels in the cells were analyzed. We found toxicological effects of e-cigarette vapor and the pure carrier substances, whereas the nicotine concentration did not have an effect on the cell viability. The viability of mainstream smoke cigarette exposed cells was 4.5–8 times lower and the oxidative stress levels 4.5–5 times higher than those of e-cigarette vapor exposed cells, depending on the donor. Our experimental setup delivered reproducible data and thus provides the opportunity for routine testing of e-cigarette liquids to ensure safety and quality for the user.

  17. Fuel cells using ionic liquids as electrolyte and operating at room temperature; Celulas de combustivel utilizando como eletrolito liquidos ionicos e operando a temperatura ambiente

    Energy Technology Data Exchange (ETDEWEB)

    Botton, Janine Padilha; Souza, Roberto Fernando de; Goncalves, Reinaldo Simoes; Dupont, Jairton [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica], e-mail: janine@iq.ufrgs.br

    2004-07-01

    The room temperature imidazolium based ionic liquids, such as 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4) are outstanding electrolytes for fuel cells. A 67% overall cell efficiency is achieve using these liquids as supporting electrolytes for a commercially available alkaline fuel cell (AFC) at room temperature operating with air and hydrogen at atmospheric pressure. (author)

  18. Organic solar cells based on liquid crystalline and polycrystalline thin films

    Science.gov (United States)

    Yoo, Seunghyup

    This dissertation describes the study of organic thin-film solar cells in pursuit of affordable, renewable, and environmentally-friendly energy sources. Particular emphasis is given to the molecular ordering found in liquid crystalline or polycrystalline films as a way to leverage the efficiencies of these types of cells. Maximum efficiencies estimated based on excitonic character of organic solar cells show power conversion efficiencies larger than 10% are possible in principle. However, their performance is often limited due to small exciton diffusion lengths and poor transport properties which may be attributed to the amorphous nature of most organic semiconductors. Discotic liquid crystal (DLC) copper phthalocyanine was investigated as an easily processible building block for solar cells in which ordered molecular arrangements are enabled by a self-organization in its mesophases. An increase in photocurrent and a reduction in series resistance have been observed in a cell which underwent an annealing process. X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements suggest that structural and morphological changes induced after the annealing process are related to these improvements. In an alternative approach, p-type pentacene thin films prepared by physical vapor deposition were incorporated into heterojunction solar cells with C60 as n-type layers. Power conversion efficiencies of 2.7% under broadband illumination (350--900 nm) with a peak external quantum efficiency of 58% have been achieved with the broad spectral coverage across the visible spectrum. Analysis using an exciton diffusion model shows this efficient carrier generation is mainly due to the large exciton diffusion length of pentacene films. Joint XRD and AFM studies reveal that the highly crystalline nature of pentacene films can account for the observed large exciton diffusion length. In addition, the electrical characteristics are studied as a function of light intensity using

  19. Importance and Challenges of Electrochemical in Situ Liquid Cell Electron Microscopy for Energy Conversion Research.

    Science.gov (United States)

    Hodnik, Nejc; Dehm, Gerhard; Mayrhofer, Karl J J

    2016-09-20

    The foreseeable worldwide energy and environmental challenges demand renewable alternative sources, energy conversion, and storage technologies. Therefore, electrochemical energy conversion devices like fuel cells, electrolyzes, and supercapacitors along with photoelectrochemical devices and batteries have high potential to become increasingly important in the near future. Catalytic performance in electrochemical energy conversion results from the tailored properties of complex nanometer-sized metal and metal oxide particles, as well as support nanostructures. Exposed facets, surface defects, and other structural and compositional features of the catalyst nanoparticles affect the electrocatalytic performance to varying degrees. The characterization of the nanometer-size and atomic regime of electrocatalysts and its evolution over time are therefore paramount for an improved understanding and significant optimization of such important technologies like electrolyzers or fuel cells. Transmission electron microscopy (TEM) and scanning transmission electron microscope (STEM) are to a great extent nondestructive characterization tools that provide structural, morphological, and compositional information with nanoscale or even atomic resolution. Due to recent marked advancement in electron microscopy equipment such as aberration corrections and monochromators, such insightful information is now accessible in many institutions around the world and provides huge benefit to everyone using electron microscopy characterization in general. Classical ex situ TEM characterization of random catalyst locations however suffers from two limitations regarding catalysis. First, the necessary low operation pressures in the range of 10(-6) to 10(-9) mbar for TEM are not in line with typical reaction conditions, especially considering electrocatalytic solid-liquid interfaces, so that the active state cannot be assessed. Second, and somewhat related, is the lack of time resolution for the

  20. The relationship of freeze tolerance with intracellular compounds in baker's yeasts.

    Science.gov (United States)

    Shi, Xiaojian; Miao, Yelian; Chen, Jie Yu; Chen, Jun; Li, Wenli; He, Xun; Wang, Jining

    2014-03-01

    Freeze-tolerant baker's yeasts are required for the processing of frozen doughs. The present study was carried out to investigate the cell survival rate after frozen storage and the change of fermentability in dough due to frozen storage, and to discuss quantitatively the relationship of freeze tolerance with intracellular trehalose, amino acids, and glycerol, using six types of baker's yeasts as the test materials. The experimental results showed that the fermentability of yeast cells in frozen dough was strongly correlated with the cell survival rate. The baker's yeast with a higher level of cell survival rate had a larger increase in the total intracellular compound content after frozen storage, and the cell survival rate increased linearly with increasing total intracellular compound content in frozen yeast cells. Trehalose was a primary compound affecting freeze tolerance, followed by glutamic acid, arginine, proline, asparagic acid, and glycerol. The basic information provided by the present study is useful for exploring the freeze-tolerance mechanisms of baker's yeast cells, breeding better freeze-tolerant baker's yeast strains, and developing more effective cryoprotectants. PMID:24482281

  1. Characterization of solar cells for space applications. Volume 14: Electrical characteristics of Hughes liquid phase epitaxy gallium arsenide solar cells as a function of intensity, temperature and irradiation

    Science.gov (United States)

    Anspaugh, B. E.; Downing, R. G.; Miyahira, T. F.; Weiss, R. S.

    1981-01-01

    Electrical characteristics of liquid phase epitaxy, P/N gallium aluminum arsenide solar cells are presented in graphical and tabular format as a function of solar illumination intensity and temperature. The solar cells were exposed to 1 MeV electron fluences of, respectively, 0, one hundred trillion, one quadrillion, and ten quadrillion e/sq cm.

  2. Lipid composition of commercial bakers' yeasts having different freeze-tolerance in frozen dough.

    Science.gov (United States)

    Murakami, Y; Yokoigawa, K; Kawai, F; Kawai, H

    1996-11-01

    The lipid composition of some commercial bakers' yeasts having different freeze-sensitivity in frozen dough was investigated to clarify the correlation between their lipid composition and freeze-tolerance. The total lipid content including neutral lipid, free fatty acid, sterol, and phospholipid ranged between 23.0 to 32.2 mg/100 mg protein of the yeasts tested. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine were the main phospholipids found in all yeast strains, but no distinct difference in these components between freeze-tolerant and freeze-sensitive strains was observed. Palmitoleic (C16:1), oleic (C18:1), palmitic (16:0), and stearic (C18:0) acids were the major fatty acids present in total lipid and phospholipid, and unsaturation indices of fatty acid in these lipid components were almost equal by the strains. The molar ratios of sterol to phospholipid of freeze-sensitive strains were higher than those of freeze-tolerant strains. The difference in the sterol-phospholipid ratio that influences the fluidity of plasma membranes in yeast cells was supposed to reflect the difference in freeze-sensitivity of bakers' yeast. PMID:8987866

  3. Development of Three-Layer Simulation Model for Freezing Process of Food Solution Systems

    Science.gov (United States)

    Kaminishi, Koji; Araki, Tetsuya; Shirakashi, Ryo; Ueno, Shigeaki; Sagara, Yasuyuki

    A numerical model has been developed for simulating freezing phenomena of food solution systems. The cell model was simplified to apply to food solution systems, incorporating with the existence of 3 parts such as unfrozen, frozen and moving boundary layers. Moreover, the moving rate of freezing front model was also introduced and calculated by using the variable space network method proposed by Murray and Landis (1957). To demonstrate the validity of the model, it was applied to the freezing processes of coffee solutions. Since the model required the phase diagram of the material to be frozen, the initial freezing temperatures of 1-55 % coffee solutions were measured by the DSC method. The effective thermal conductivity for coffee solutions was determined as a function of temperature and solute concentration by using the Maxwell - Eucken model. One-dimensional freezing process of 10 % coffee solution was simulated based on its phase diagram and thermo-physical properties. The results were good agreement with the experimental data and then showed that the model could accurately describe the change in the location of the freezing front and the distributions of temperature as well as ice fraction during a freezing process.

  4. Pulmonary delivery of an inulin-stabilized influenza subunit vaccine prepared by spray-freeze drying induces systemic, mucosal humoral as well as cell-mediated immune responses in BALB/c mice

    NARCIS (Netherlands)

    Amorij, J-P.; Saluja, V.; Petersen, A.H.; Hinrichs, W.L.J.; Huckriede, A.; Frijlink, H.W.

    2007-01-01

    In this study pulmonary vaccination with a new influenza subunit vaccine powder was evaluated. Vaccine powder was produced by spray-freeze drying (SFD) using the oligosaccharide inulin as stabilizer. Immune responses after pulmonary vaccination of BALB/c mice with vaccine powder were determined and

  5. Comparison of Efficacy in Abnormal Cervical Cell Detection between Liquid-based Cytology and Conventional Cytology.

    Science.gov (United States)

    Tanabodee, Jitraporn; Thepsuwan, Kitisak; Karalak, Anant; Laoaree, Orawan; Krachang, Anong; Manmatt, Kittipong; Anontwatanawong, Nualpan

    2015-01-01

    This study was conducted to 1206 women who had cervical cancer screening at Chonburi Cancer Hospital. The spilt-sample study aimed to compare the efficacy of abnormal cervical cells detection between liquid-based cytology (LBC) and conventional cytology (CC). The collection of cervical cells was performed by broom and directly smeared on a glass slide for CC then the rest of specimen was prepared for LBC. All slides were evaluated and classified by The Bethesda System. The results of the two cytological tests were compared to the gold standard. The LBC smear significantly decreased inflammatory cell and thick smear on slides. These two techniques were not difference in detection rate of abnormal cytology and had high cytological diagnostic agreement of 95.7%. The histologic diagnosis of cervical tissue was used as the gold standard in 103 cases. Sensitivity, specificity, positive predictive value, negative predictive value, false positive, false negative and accuracy of LBC at ASC-US cut off were 81.4, 75.0, 70.0, 84.9, 25.0, 18.6 and 77.7%, respectively. CC had higher false positive and false negative than LBC. LBC had shown higher sensitivity, specificity, PPV, NPV and accuracy than CC but no statistical significance. In conclusion, LBC method can improve specimen quality, more sensitive, specific and accurate at ASC-US cut off and as effective as CC in detecting cervical epithelial cell abnormalities. PMID:26514540

  6. Fabrication of protic ionic liquid/sulfonated polyimide composite membranes for non-humidified fuel cells

    Science.gov (United States)

    Lee, Seung-Yul; Yasuda, Tomohiro; Watanabe, Masayoshi

    We have demonstrated that a protic ionic liquid, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) functions as a proton conductor and is suitable for use as an electrolyte in H 2/O 2 fuel cells, which can be operated at temperatures higher than 100 °C under non-humidified conditions. In this study, in order to fabricate a polymer electrolyte fuel cell, matrix polymers for [dema][TfO] are explored and sulfonated polyimides (SPI), in which the sulfonic acid groups are in diethylmethylammonium form, are found to be highly compatible with [dema][TfO]. Polymer electrolyte membranes for non-humidified fuel cells are prepared by the solvent casting method using SPI and [dema][TfO]. The SPI, with an ion exchange capacity of 2.27 meq g -1, can retain four times its own weight of [dema][TfO] and produces uniform, tough, and transparent composite membranes. The composite membranes have good thermal stability (>300 °C) and ionic conductivity (>10 -2 S cm -1 at 120 °C when the [dema][TfO] content is higher than 67 wt%) under anhydrous conditions. In the H 2/O 2 fuel cell operation using a composite membrane without humidification, a current density higher than 240 mA cm -2 is achieved with a maximum power density of 100 mW cm -2 at 80 °C.

  7. Jin Fu Kang Oral Liquid Inhibits Lymphatic Endothelial Cells Formation and Migration

    Directory of Open Access Journals (Sweden)

    Hai-Lang He

    2016-01-01

    Full Text Available Lung cancer is the leading cause of cancer-related deaths worldwide. Jin Fu Kang (JFK, an oral liquid prescription of Chinese herbal drugs, has been clinically available for the treatment of non-small cell lung cancer (NSCLC. Lymphangiogenesis is a primary event in the process of cancer development and metastasis, and the formation and migration of lymphatic endothelial cells (LECs play a key role in the lymphangiogenesis. To assess the activity of stromal cell-derived factor-1 (SDF-1 and the coeffect of SDF-1 and vascular endothelial growth factor-C (VEGF-C on the formation and migration of LECs and clarify the inhibitory effects of JFK on the LECs, the LECs were differentiated from CD34+/VEGFR-3+ endothelial progenitor cells (EPCs, and JFK-containing serums were prepared from rats. SDF-1 and VEGF-C both induced the differentiation of CD34+/VEGFR-3+ EPCs towards LECs and enhanced the LECs migration. Couse of SDF-1 and VEGF-C displayed an additive effect on the LECs formation but not on their migration. JFK inhibited the formation and migration of LECs, and the inhibitory effects were most probably via regulation of the SDF-1/CXCR4 and VEGF-C/VEGFR-3 axes. The current finding suggested that JFK might inhibit NSCLC through antilymphangiogenesis and also provided a potential to discover antilymphangiogenesis agents from natural resources.

  8. Effect of different freezing methods on the quality and microstructure of lotus root slices%冻结方式对莲藕片品质及微观结构的影响

    Institute of Scientific and Technical Information of China (English)

    王远; 刘春菊; 刘春泉; 宋江峰; 李大婧

    2015-01-01

    为了研究速冻莲藕片冻结方式对其质地和品质的影响,本研究通过液氮、超低温冰箱和普通冰箱3种冻结方式处理,分析莲藕片质构、自由液滴、维生素C、色泽和微观结构的变化。结果表明:液氮和超低温冰箱冻结属部分玻璃态冻结,普通冰箱冻结为橡胶态冻结。液氮和超低温冰箱冻结的莲藕片细胞结构完整,细胞排列整齐,但速冻仍使部分细胞受损;普通冰箱冻结的莲藕片细胞结构破坏严重,细胞被压扁变形,细胞质溶出,细胞壁降解收缩。超低温冰箱冻结莲藕片品质最佳,莲藕片质构、自由液滴和维生素C 损失较少;液氮冻结莲藕片色泽最佳,但会出现冻裂现象;普通冰箱冻结莲藕片汁液流失、品质下降最为严重。表明超低温冰箱冻结是速冻莲藕最佳的冻结方式。%To study the effect of freezing methods on texture and quality of lotus root slices, texture profile, free titer, vitamin C, color and microstructure of lotus root slices by liquid nitrogen freezing, ultra-low temperature freezer freezing and general fridge freezing were analyzed. Liquid nitrogen and ultra-low temperature freezer were partial glassy freezing, while the general fridge was rubbery freezing. Frozen lotus root slices by ultra-low temperature freezer showed less losses of texture, free titer and vitamin C. The color of lotus root slices by liquid nitrogen freezing was the best, but frost occurred. The loss of juice and quality declining was the most severe by general fridge freezing. Cells of fro-zen lotus root slices by liquid nitrogen and ultra-low temperature freezer were structural integrated and lined up, how-ever, some were impacied. Cell structure of lotus root slices by general fridge was damaged seriously; cells were squashed, cytoplasm was dissolved, and cell wall degraded. In conclusion, ultra-low temperature freezer was the best way to cryopreserve lotus root slices.

  9. Exploring the Nature of Contact Freezing

    Science.gov (United States)

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

    2012-12-01

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

  10. A study of gas bubbles in liquid mercury in a vertical Hele-Shaw cell

    International Nuclear Information System (INIS)

    High-quality observations of mesoscopic gas bubbles in liquid metal are vital for a further development of pyrometallurgical gas injection reactors. However, the opacity of metals enforces the use of indirect imaging techniques with limited temporal or spatial resolution. In addition, accurate interface tracking requires tomography which further complicates the design of a high-temperature experimental setup. In this paper, an alternative approach is suggested that circumvents these two main restrictions. By injecting gas in a thin layer of liquid metal entrapped between two flat and closely spaced plates, bubbles in a Hele-Shaw flow regime are generated. The resulting quasi-2D multiphase flow phenomena can be fully captured from a single point of view and, when using a non-wetted transparent plate material, the bubbles can be observed directly. The feasibility of this approach is demonstrated by observations on buoyancy-driven nitrogen bubbles in liquid mercury in a vertical Hele-Shaw cell. By using a moving high-speed camera to make continuous close up recordings of individual bubbles, the position and geometry of these bubbles are quantified with a high resolution along their entire path. After a thorough evaluation of the experimental accuracy, this information is used for a detailed analysis of the bubble expansion along the path. While the observed bubble growth is mainly caused by the hydrostatic pressure gradient, a careful assessment of the volume variations for smaller bubbles shows that an accurate bubble description should account for significant dynamic pressure variations that seem to be largely regime dependent. (orig.)

  11. Effect of the technology of high cell density cultivation and vacuum freeze-drying on cryotolerance property of lactic acid bacteria%高密度发酵和真空冷冻干燥工艺对乳酸菌抗冷冻性的影响

    Institute of Scientific and Technical Information of China (English)

    刘彩虹; 邵玉宇; 任艳; 孟和毕力格; 张和平

    2013-01-01

    经真空冷冻干燥得到的乳酸菌发酵剂存活率和后期的低温贮藏稳定性与诸多因素相关.本文综述了制备乳酸菌发酵剂过程中高密度发酵和真空冷冻干燥工艺的不同对乳酸菌抗冷冻性的影响,其中高密度发酵过程中的培养基组分、培养温度、发酵恒定pH、中和剂的选择、菌体收获时期和发酵结束后处理以及真空冷冻干燥过程中保护剂的添加、预冷冻处理等是影响乳酸菌抗冷冻性的重要因素.通过对这些相关因素的综述分析,为提高乳酸菌发酵剂的冻干存活率和后期的低温贮藏稳定性提供新的思路,且应用抗冷冻性强、活力高的乳酸菌发酵剂对有效提高乳制品的质量和企业的经济效益意义重大.%The survival rate and low temperature stability of lactic acid bacterial starter obtained by vacuum freeze-drying are governed by several factors. In this paper, the influence of the technology of high cell density cultivation and vacuum freeze-drying on cryotolerance of lactic acid bacteria for use as starters was analyzed. During fermentation, the following factors had a significant effect on the cryosurvival of lactic acid bacteria: culture medium, temperature control, pH stat, the neutralizer used, the harvesting stage of the cell crop, and post-fermentation handling of the concentrated cells. Factors affecting cell viability subjected to lyophilization include the following: cryoprotectants used, conditions used in initial freezing of the cell concentrate, and during vacuum freeze-drying. A good understanding of these factors will provide a reliable technology for preserving high cell density starter. The use of starter bacteria with high cryotolerance and viability can improve the quality of fermented milk products and boost economic benefits to the dairy industry.

  12. Fabrication of twisted nematic structure and vector grating cells by one-step exposure on photocrosslinkable polymer liquid crystals.

    Science.gov (United States)

    Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2012-03-15

    We present a simple yet efficient method to automatically fabricate the twisted nematic structure by one-step exposure on an empty glass cell coated with photocrosslinkable polymer liquid crystal (PCLC) films. The resultant photoalignment directions of two substrates can be orthogonal to each other by controlling the difference between the exposure energy for upper and lower PCLC films and the twisted nematic (TN) structure can be automatically fabricated. The vector grating liquid crystalline cell with TN structure was also fabricated by means of a developed method, and the diffraction properties were well explained by the theoretical calculation on the basis of Jones calculus. PMID:22446243

  13. A new application of the SFDA-staining method to assessment of the freezing tolerance in leaves of alpine plants

    OpenAIRE

    Yamori,Wataru/Kogami,Hiroyuki/Masuzawa,Takehiro

    2006-01-01

    For the first time, this study used 5- (6-) sulfofluorescein diacetate (SFDA), a fluorescent product in plant cells converted by esterase activity to fluorescein-5- (and 6-) sulfonic acid (FSA), to assess the freezing tolerance of leaf cells. We were able to readily distinguish living and dead cells, and detect differences in freezing tolerance among five alpine plants using the SFDA-staining method. We also compared this method with two conventional methods, the electrolyte leakage test and ...

  14. Liquid phase crystallized silicon on glass: Technology, material quality and back contacted heterojunction solar cells

    Science.gov (United States)

    Haschke, Jan; Amkreutz, Daniel; Rech, Bernd

    2016-04-01

    Liquid phase crystallization has emerged as a novel approach to grow large grained polycrystalline silicon films on glass with high electronic quality. In recent years a lot of effort was conducted by different groups to determine and optimize suitable interlayer materials, enhance the crystallographic quality or to improve post crystallization treatments. In this paper, we give an overview on liquid phase crystallization and describe the necessary process steps and discuss their influence on the absorber properties. Available line sources are compared and different interlayer configurations are presented. Furthermore, we present one-dimensional numerical simulations of a rear junction device, considering silicon absorber thicknesses between 1 and 500 µm. We vary the front surface recombination velocity as well as doping density and minority carrier lifetime in the absorber. The simulations suggest that a higher absorber doping density is beneficial for layer thicknesses below 20 µm or when the minority carrier lifetime is short. Finally, we discuss possible routes for device optimization and propose a hybride cell structure to circumvent current limitations in device design.

  15. Liquid biopsy and therapeutic response: Circulating tumor cell cultures for evaluation of anticancer treatment

    Science.gov (United States)

    Khoo, Bee Luan; Grenci, Gianluca; Jing, Tengyang; Lim, Ying Bena; Lee, Soo Chin; Thiery, Jean Paul; Han, Jongyoon; Lim, Chwee Teck

    2016-01-01

    The lack of a robust anticancer drug screening system to monitor patients during treatment delays realization of personalized treatment. We demonstrate an efficient approach to evaluate drug response using patient-derived circulating tumor cell (CTC) cultures obtained from liquid biopsy. Custom microfabricated tapered microwells were integrated with microfluidics to allow robust formation of CTC clusters without pre-enrichment and subsequent drug screening in situ. Rapid feedback after 2 weeks promotes immediate intervention upon detection of drug resistance or tolerance. The procedure was clinically validated with blood samples (n = 73) from 55 patients with early-stage, newly diagnosed, locally advanced, or refractory metastatic breast cancer. Twenty-four of these samples were used for drug evaluation. Cluster formation potential correlated inversely with increased drug concentration and therapeutic treatment. This new and robust liquid biopsy technique can potentially evaluate patient prognosis with CTC clusters during treatment and provide a noninvasive and inexpensive assessment that can guide drug discovery development or therapeutic choices for personalized treatment.

  16. Inducing effects of macrophage stimulating protein on the expansion of early hematopoietic progenitor cells in liquid culture

    Institute of Scientific and Technical Information of China (English)

    MA Li-xia; HUANG Yan-hong; CHENG La-mei; LEI Jun; WANG Qi-ru

    2007-01-01

    Background Macrophage stimulating protein (MSP) is produced by human bone marrow endothelial cells. In this study,we sought to observe its effects on inducing the expansion of early hematopoietic progenitor cells which were cultured in a liquid culture system in the presence of the combination of stem cell factor (SCF), interleukin 3 (IL-3), interleukin 6 (IL-6), granulocyte macrophage-colony stimulating factor (GM-CSF), erythropoietin (EPO) (Cys) and MSP or of Cys and bone marrow endothelial cell conditioned medium (EC-CM).Methods Human bone marrow CD34+ cells were separated and cultured in a liquid culture system for 6 days.Granulocyte-macrophage colony forming unit (CFU-GM) and colony forming unit-granulocyte, erythrocyte, macrophage,megakaryocyte (CFU-GEMM) were employed to assay the effects of different treatment on the proliferation of hematopoeitic stem/progenitor cells. The nitroblue tetrazolium (NBT) reductive test and hoechest 33258 staining were employed to reflect the differentiation and apoptosis of the cells respectively.Results MSP inhibited the proliferation of CFU-GM and CFU-GEMM in semi-solid culture and the inhibitory effect on CFU-GEMM was stronger than on CFU-GM. MSP inhibited the differentiation of early hematopoietic progenitor cells induced by hematopoietic stimulators. Bone marrow (BM) CFU-GEMM was 2.3-fold or 1.7-fold increase or significantly decreased in either Cys+EC-CM, Cys+MSP or Cys compared with 0 hour control in liquid culture system after 6 days.Conclusion MSP, a hematopoietic inhibitor, inhibits the differentiation of early hematopoietic progenitor cells induced by hematopoietic stimulators and makes the early hematopoietic progenitor cells expand in a liquid culture system.

  17. Cost-effective platinum alloy counter electrodes for liquid-junction dye-sensitized solar cells

    Science.gov (United States)

    Li, Yanjuan; Tang, Qunwei; Yu, Liangmin; Yan, Xuefeng; Dong, Lei

    2016-02-01

    One of the challenges in developing advanced dye-sensitized solar cells (DSSCs) is the pursuit of cost-effective and robust counter electrodes (CEs). We present here the successful synthesis of binary PtxM100-x (M = Ni, Co, Fe) alloy nanostructures on Ti foil by a facile and environmental-friendly strategy for utilization as CEs in liquid-junction DSSCs. Due to the reasonable charge-transfer ability and excellent electrocatalytic activity, the resultant DSSC yields a promising power conversion efficiency (PCE) of 6.42% with binary Pt0.28Ni99.72 CE in comparison with 6.18% for pristine Pt CE based device. The easy synthesis, cost-effectiveness, and good electrocatalytic property may help the Pt0.28Ni99.72 nanostructure stand out as an alternative CE electrocatalyst in a DSSC.

  18. Recording of polarization holograms in a liquid crystal cell with a photosensitive chalcogenide orientation layer [Invited].

    Science.gov (United States)

    Sheremet, Nina; Kurioz, Yuriy; Slyusarenko, Kostyantyn; Trunov, Michael; Reznikov, Yuriy

    2013-08-01

    Polarization gratings have been recorded in a combined liquid crystal (LC) cell made of a substrate covered with a photosensitive chalcogenide orientation layer and a reference substrate covered with a rubbed polyimide film. The gratings are formed due to the spatially modulated light-induced easy orientation axis on the chalcogenide surface recorded by two beams with opposite circular polarizations. The gratings are permanent, but they can be erased by one of the recording beams and re-recorded. The diffraction intensity of the circularly polarized light is achromatic and does not depend on the birefringence of the LC. The diffraction efficiency of the grating is of the order of a few percents. Application of an ac field causes a strong increase of the diffraction efficiency up to 45%. PMID:23913086

  19. Novel cell parameter determination of a twisted-nematic liquid crystal display

    Institute of Scientific and Technical Information of China (English)

    Huang Xia; Jing Hai; Fu Guo-Zhu

    2008-01-01

    In this paper a novel method is proposed to determine the cell parameters including the twist angle, optic retardation and rubbing direction of twisted-nematic liquid crystal displays (TNLCD) by rotating the TNLCD. It is a single-wavelength method. Because using subtraction equation of transmittance as curve fitting equation, the influence of the light from environment and the absorption by polarizer, the sample of TNLCD and analyser on the transmittance is eliminated. Accurate results can also be obtained in imperfect darkness. By large numbers of experiments, we found that not only the experimental setup is quite simple and can be easily adopted to be carried out, but also the results are accurate.

  20. Polyoxymetalate liquid-catalyzed polyol fuel cell and the related photoelectrochemical reaction mechanism study

    Science.gov (United States)

    Wu, Weibing; Liu, Wei; Mu, Wei; Deng, Yulin

    2016-06-01

    A novel design of liquid catalyzed fuel cell (LCFC), which uses polyoxometalates (POMs) as the photocatalyst and charge carrier has been reported previously. In this paper, the adaptability of biomass fuels (e.g., glycerol and glucose) to the LCFC and corresponding cell performance were studied in detail here. An interesting finding that greatly differs from conventional fuel cell is that high molecular weight fuels rather than small molecule fuels (e.g., methanol and ethylene glycol) are favored by the novel LCFC with respect to the power densities. The power output of LCFC strongly depends on the number and structure of hydroxyl groups in the biomass fuels. The evidence of UV-Vis and 1H NMR spectra shows that the preassociation between POM and alcohol fuels, which determines the photoelectrochemical reaction pathway of POM, is enhanced as the number of hydroxyl increases. Experimental results also demonstrate that more hydroxyl groups in the molecules lead to faster photoelectrochemical reaction between POM and fuels, higher reduction degree of POM, and further higher power output of LCFC. Our study reveals that biomass-based polyhydroxyl compounds such as starch, hemicellulose and cellulose are potential high-performance fuels for LCFC.

  1. Simultaneous liquid chromatographic determination of carotenoids, retinoids, and tocopherols in human buccal mucosal cells.

    Science.gov (United States)

    Peng, Y S; Peng, Y M

    1992-01-01

    Epidemiological and experimental data have suggested that some micronutrients, including various carotenoids, retinoids, and alpha-tocopherol, may have chemopreventive activity against certain types of human cancer. In order to define the role of these micronutrients in cancer prevention, it is necessary to measure their concentrations in the target tissues, since these are critical to the chemopreventive effect. We have developed a sensitive and reproducible high-performance liquid chromatography procedure for the simultaneous determination of lutein, zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, beta-carotene, cis-beta-carotene, retinol, retinyl palmitate, alpha-tocopherol, and gamma-tocopherol in an easily accessible human target tissue, the buccal mucosal cells. This procedure used a gradient of two mobile phases which consisted of acetonitrile, tetrahydrofuran, methanol, 1% ammonium acetate, and butylated hydroxytoluene (in v/v/v/v/w): mobile phase A, 85:5:5:5:0.05; mobile phase B, 55:35:5:5:0.05. The run time, including reequilibration, was 47 min: from 100% A to 100% B in 27 min, remaining at that mobile phase for 10 min, then back to 100% A at 43 min at a constant flow rate of 1.3 ml/min. The high-performance liquid chromatography effluent was monitored at 300, 325, and 452 nm for tocopherols, retinoids, and carotenoids, respectively, with a photodiode array detector. The average recovery was 83% for lycopene and > 92% for others. The precision of the assay for all the compounds was less than 10% in a 1-month period. The micronutrients were extracted by incubating the cells with protease, followed by vortex mixing with 1% sodium dodecyl sulfate in ethanol containing 0.1% butylated hydroxytoluene, and, finally, hexane extraction.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1305470

  2. The influence of freezing and tissue porosity on the material properties of vegetable tissues

    CERN Document Server

    Ralfs, J D

    2002-01-01

    Tissue porosity and fluid flow have been shown to be important parameters affecting the mechanical and sensorial behaviour of edible plant tissues. The quantity of fluid and the manner with which it was released on compression of the plant tissue were also important regarding the sensory perception and a good indication of any structural damage resulting from freezing, for example. Potato, carrot and Chinese water chestnut were used to study the effects freezing has on model plant tissues. Mechanical and structural measurements of the plant tissue were correlated with sensory analysis. Conventional freezing was shown to cause severe structural damage predominantly in the form of cavities between or through cells, resulting in decreases in mechanical strength and stiffness, and samples that were perceived in the mouth as 'soft' and 'wet'. The location and size of the cavities formed from ice crystals, depended on the particular plant tissue being frozen, the processing it was subjected to prior to freezing, th...

  3. Advanced control of liquid water region in diffusion media of polymer electrolyte fuel cells through a dimensionless number

    Science.gov (United States)

    Wang, Yun; Chen, Ken S.

    2016-05-01

    In the present work, a three-dimension (3-D) model of polymer electrolyte fuel cells (PEFCs) is employed to investigate the complex, non-isothermal, two-phase flow in the gas diffusion layer (GDL). Phase change in gas flow channels is explained, and a simplified approach accounting for phase change is incorporated into the fuel cell model. It is found that the liquid water contours in the GDL are similar along flow channels when the channels are subject to two-phase flow. Analysis is performed on a dimensionless parameter Da0 introduced in our previous paper [Y. Wang and K. S. Chen, Chemical Engineering Science 66 (2011) 3557-3567] and the parameter is further evaluated in a realistic fuel cell. We found that the GDL's liquid water (or liquid-free) region is determined by the Da0 number which lumps several parameters, including the thermal conductivity and operating temperature. By adjusting these factors, a liquid-free GDL zone can be created even though the channel stream is two-phase flow. Such a liquid-free zone is adjacent to the two-phase region, benefiting local water management, namely avoiding both severe flooding and dryness.

  4. Breeding of Freeze-tolerant Yeast and the Mechanisms of Stress-tolerance

    Science.gov (United States)

    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.

  5. Numerical modeling of seasonally freezing ground and permafrost

    Science.gov (United States)

    Nicolsky, Dmitry J.

    2007-12-01

    This thesis represents a collection of papers on numerical modeling of permafrost and seasonally freezing ground dynamics. An important problem in numerical modeling of temperature dynamics in permafrost and seasonally freezing ground is related to parametrization of already existing models. In this thesis, a variation data assimilation technique is presented to find soil properties by minimizing the discrepancy between in-situ measured temperatures and those computed by the models. The iterative minimization starts from an initial approximation of the soil properties that are found by solving a sequence of simple subproblems. In order to compute the discrepancy, the temperature dynamics is simulated by a new implementation of the finite element method applied to the heat equation with phase change. Despite simplifications in soil physics, the presented technique was successfully applied to recover soil properties, such as thermal conductivity, soil porosity, and the unfrozen water content, at several sites in Alaska. The recovered properties are used in discussion on soil freezing/thawing and permafrost dynamics in other parts of this thesis. Another part of this thesis concerns development of a numerical thermo-mechanical model of seasonal soil freezing on the lateral scale of several meters. The presented model explains observed differential frost heave occurring in non-sorted circle ecosystems north of the Brooks Range in the Alaskan tundra. The model takes into account conservation principles for energy, linear momentum and mass of three constituents: liquid water, ice and solid particles. The conservation principles are reduced to a computationally convenient system of coupled equations for temperature, liquid water pressure, porosity, and the velocity of soil particles in a three-dimensional domain with cylindrical symmetry. Despite a simplified rheology, the model simulates the ground surface motion, temperature, and water dynamics in soil and explains

  6. Heterogeneous freezing of water droplets containing kaolinite particles

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2011-05-01

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

  7. Freezing phenomena in ice-water systems

    Energy Technology Data Exchange (ETDEWEB)

    Akyurt, M.; Zaki, G.; Habeebullah, B. [Fakieh Center for Applied Research, Makkah Al-Mukarramah (Saudi Arabia); King Abdulaziz University, Jeddah (Saudi Arabia). Dept. of Mechanical Engineering

    2002-09-01

    The characteristics of solidification and melting are reviewed. The properties of water and ice and the phase diagram of water are discussed with special emphasis on ice density. A concise account of the freezing process and the Stefan problem is presented. To this end, the four stages of freezing are identified, supercooling, nucleation and the formation of dendritic ice, the growth of concentric rings of solid ice at 0{sup o}C and the final cooling of the solid ice are treated in some detail. The subject of bursting of pipes is given particular emphasis. Attention is drawn to a common misconception on pipe bursting and to misleading relationships for the computation of freezing time for ice blockage. Several current applications of melting and freezing systems are outlined. (author)

  8. Characterization of Caulobacter crescentus response to low temperature and identification of genes involved in freezing resistance.

    Science.gov (United States)

    Mazzon, Ricardo R; Lang, Elza A S; Braz, Vânia S; Marques, Marilis V

    2008-11-01

    Free-living bacteria must respond to a wide range of temperature changes, and have developed specific mechanisms to survive in extreme environments. In this work we describe a remarkable resistance of mesophilic bacterium Caulobacter crescentus to several cycles of freezing at -80 degrees C, which was able to grow at low temperatures. Exponentially growing cells and late stationary-phase cells presented higher freezing resistance at both -20 and -80 degrees C than early stationary-phase cells. Cryotolerance was observed when log-phase cultures grown at 30 degrees C were preincubated at 5, 15 or 20 degrees C before freezing at -20 degrees C. A transposon library was screened to identify mutants sensitive to freezing at -80 degrees C and three strains presenting <10% survival were isolated. Identification of genes disrupted in each mutant showed that they encoded an AddA family DNA helicase, a DEAD/DEAH box RNA helicase and a putative RND (resistance, nodulation, cell division) efflux system component. These strains showed longer generation times than wild-type cells when growing at 15 degrees C, with the RNA helicase mutant presenting a severe growth defect. These analyses suggest that the singular intrinsic resistance to freezing of C. crescentus is in fact a consequence of several independent traits, especially the maintenance of a proper degree of supercoiling of nucleic acids.

  9. High pressure freezing/freeze substitution fixation improves the ultrastructural assessment of Wolbachia endosymbiont-filarial nematode host interaction.

    Directory of Open Access Journals (Sweden)

    Kerstin Fischer

    Full Text Available BACKGROUND: Wolbachia α-proteobacteria are essential for growth, reproduction and survival for many filarial nematode parasites of medical and veterinary importance. Endobacteria were discovered in filarial parasites by transmission electron microscopy in the 1970's using chemically fixed specimens. Despite improvements of fixation and electron microscopy techniques during the last decades, methods to study the Wolbachia/filaria interaction on the ultrastructural level remained unchanged and the mechanisms for exchange of materials and for motility of endobacteria are not known. METHODOLOGY/PRINCIPAL FINDING: We used high pressure freezing/freeze substitution to improve fixation of Brugia malayi and its endosymbiont, and this led to improved visualization of different morphological forms of Wolbachia. The three concentric, bilayer membranes that surround the endobacterial cytoplasm were well preserved. Vesicles with identical membrane structures were identified close to the endobacteria, and multiple bacteria were sometimes enclosed within a single outer membrane. Immunogold electron microscopy using a monoclonal antibody directed against Wolbachia surface protein-1 labeled the membranes that enclose Wolbachia and Wolbachia-associated vesicles. High densities of Wolbachia were observed in the lateral chords of L4 larvae, immature, and mature adult worms. Extracellular Wolbachia were sometimes present in the pseudocoelomic cavity near the developing female reproductive organs. Wolbachia-associated actin tails were not observed. Wolbachia motility may be explained by their residence within vacuoles, as they may co-opt the host cell's secretory pathway to move within and between cells. CONCLUSIONS/SIGNIFICANCE: High pressure freezing/freeze substitution significantly improved the preservation of filarial tissues for electron microscopy to reveal membranes and sub cellular structures that could be crucial for exchange of materials between Wolbachia

  10. Positive impact of sucrose supplementation during slow freezing of cat ovarian tissues on cellular viability, follicle morphology, and DNA integrity.

    Science.gov (United States)

    Tanpradit, Nae; Comizzoli, Pierre; Srisuwatanasagul, Sayamon; Chatdarong, Kaywalee

    2015-06-01

    The objectives of the study were to (1) examine and optimize the impact of sucrose during slow freezing and (2) compare the results of two freezing methods (slow freezing and vitrification) on cellular viability (germinal and stromal cells), follicle morphology, DNA integrity, and gap junction protein expression (connexin 43 [Cx 43]). Different sucrose supplementations (0, 0.1, and 0.3 M) in standard freezing medium were compared before and after slow freezing. Ovarian tissue slow frozen using 0.1- (4.0 ± 0.4) or 0.3-M sucrose (3.9 ± 0.5) yielded better follicular viability (number of positive follicles per 0.0625 mm(2)) than the group without sucrose (1.9 ± 0.2; P sucrose-treated groups (0.1 M, 47.4% and 0.3 M, 43.5%) than the group without sucrose (0 M, 33.8%; P sucrose groups (0.1 M, 1.2% and 0.3 M, 1.9%) than the group without sucrose (7.7%; P sucrose concentrations. In terms of the freezing methods used, vitrified ovarian tissues had fewer viable follicles (3.2 ± 0.6) than the slow-freezing method (4.6 ± 0.6; P sucrose supplementation and slow-freezing method on the follicular viability, follicular histologic appearances of follicles, and apoptosis of the follicles and stromal cells in cat ovarian tissues.

  11. Improvement of tolerance to freeze-thaw stress of baker's yeast by cultivation with soy peptides.

    Science.gov (United States)

    Izawa, Shingo; Ikeda, Kayo; Takahashi, Nobuyuki; Inoue, Yoshiharu

    2007-06-01

    The tolerance to freeze-thaw stress of yeast cells is critical for frozen-dough technology in the baking industry. In this study, we examined the effects of soy peptides on the freeze-thaw stress tolerance of yeast cells. We found that the cells cultured with soy peptides acquired improved tolerance to freeze-thaw stress and retained high leavening ability in dough after frozen storage for 7 days. The final quality of bread regarding its volume and texture was also improved by using yeast cells cultured with soy peptides. These findings promote the utilization of soy peptides as ingredients of culture media to improve the quality of baker's yeast. PMID:17505771

  12. Effect of surface viscosity, anchoring energy, and cell gap on the response time of nematic liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Souza, R.F. de [Departamento de Física, Universidade Estadual de Maringá, Avenida Colombo 5790, 87020 - 900 Maringá –PR (Brazil); Yang, D.-Ke [Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242 (United States); Lenzi, E.K.; Evangelista, L.R. [Departamento de Física, Universidade Estadual de Maringá, Avenida Colombo 5790, 87020 - 900 Maringá –PR (Brazil); Zola, R.S., E-mail: rzola@utfpr.edu.br [Departamento de Física, Universidade Estadual de Maringá, Avenida Colombo 5790, 87020 - 900 Maringá –PR (Brazil); Universidade Tecnologica Federal do Paraná, Rua Marcilio Dias 635, 86812-460 Apucarana, Paraná (Brazil)

    2014-07-15

    An analytical expression for the relaxation time of a nematic liquid crystal is obtained for the first time by considering the influence of surface viscosity, anchoring energy strength and cell gap, validated numerically by using the so-called relaxation method. This general equation for the molecular response time (τ{sub 0}) was derived for a vertical aligned cell and by solving an eigenvalue equation coming from the usual balance of torque equation in the Derzhanskii and Petrov formulation, recovering the usual equations in the appropriate limit. The results show that τ∼d{sup b}, where b=2 is observed only for strongly anchored cells, while for moderate to weak anchored cells, the exponent lies between 1 and 2, depending on both, surface viscosity and anchoring strength. We found that the surface viscosity is important when calculating the response time, specially for thin cells, critical for liquid crystal devices. The surface viscosity’s effect on the optical response time with pretilt is also explored. Our results bring new insights about the role of surface viscosity and its effects in applied physics. - Highlights: • The relaxation of nematic liquid crystals is calculated by taking the surface viscosity into account. • An analytical expression for the relaxation time depending on surface viscosity, anchoring strength and cell gap is obtained. • The results are numerically verified. • Surface viscosity is crucial for thin and weak anchored cells. • The effect on optical time and pretilt angle is also studied.

  13. High-voltage liquid-electrolyte microbatteries composed of serial unit cells defined by the surface-tension effect

    International Nuclear Information System (INIS)

    We present high-voltage liquid-electrolyte microbatteries, inspired by the high-voltage generation mechanism of electric eels using serially connected unit cells. Compared to the previous stacked micropower sources, the present microbatteries achieve easy liquid-electrolyte filling with reduced charging time. In order to isolate each cell, we purge air into the liquid electrolyte filled in a channel layer, with three types of surface-tension valves (cell-front, outlet and cell-end valves). We design and characterize four different prototypes of microbatteries: C1, C10, C20 and C40, composed of the serial interconnection of 1, 10, 20 and 40 unit cells, respectively. In the experimental study, we measure threshold pressures of the three surface tension valves of cell-front, outlet and cell-end valves as 460 ± 47, 1000 ± 53 and 2800 ± 170 Pa, respectively. The average charging time of C40 has been measured as 26.8 ± 4.9 s where the electrolyte and air flow rates are 100 and 200 μl min−1, respectively. The prototypes of the microbattery C40 show a maximum voltage of 12 V, a maximum power density of 110 μW cm−2 and a maximum power capacity of 2.1 μAh cm−2. The present microbatteries have the potential for application in high-voltage portable power sources

  14. 冻干无佐剂Veto细胞狂犬病疫苗免疫应答动态观察%A dynamic observation on the immune response to the freeze-dried without adjuvant Veto cell rabies vaccine

    Institute of Scientific and Technical Information of China (English)

    杨书宏; 陈胤忠; 陈万庚; 姜仁杰; 沈进进; 吴巨飞; 何飞; 王立成

    2009-01-01

    目的 评价国产冻干无佐剂Vero细胞狂犬病疫苗的免疫原性.方法 选择既往无明确狂犬病疫苗接种史和犬伤史、符合研究方案制定的入选标准和排除标准为研究对象,对暴露于狂犬病的患者采用常规5针注射.观察对象于首针接种前、首针接种后7、14、28、45 d,全程后6个月采集血样检测抗狂犬病中和抗体.结果 符合入选标准和排除标准的观察对象90名常规接种5针冻干无佐剂Vero细胞狂犬病疫苗.观察对象接种前狂犬病抗体均为阴性,接种首针后7 d狂犬病抗体阳转率为12.22%,接种首针后14 d阳转率达到100%,接种首针后28、45 d和全程后6个月的阳性率均为100%.接种首针后7 d抗狂犬病病毒综合抗体的几何抗体平均滴度(GMT)仅为0.27 IU/ml,接种首针后14 d狂犬病抗体的GlVlT达到2.52 IU/ml,较首针接种后7 d增长9.33倍.接种首针后28、45 d狂犬病抗体的GMT分别达到4.43、7.08 IU/ml,较首针后14 d分别增长1.76倍、2.81倍.全程接种后6个月狂犬病抗体的GMT仍达到8.41 IU/ml.结论 国产冻干无佐剂Vero细胞狂犬病疫苗具有良好的免疫原性,6个月内再被暴露于狂犬病动物者可以不需要接种狂犬病疫苗.%Objective The purpose of the present study was to evaluate the immunogenicity of the freeze-dried without adjuvant Vero cell rabies vaccine made in China. Methods A conventional vaccination procedure that included 5 injections of vaccine was applied to 90 patients who had exposed to rabies and were without history of rabies vaccination and dog bite injury, selected according to the requirements for recruitment and exclusion in the project. Blood samples were acquired before the first vaccination, 7, 14, 28 and45 days after the first vaccination and 180 days after the whole procedure of vaccination, respectively, for determination of anti-rabies neutralizing antibody. Results No anti-rabies neutralizing antibody was detected before the

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

    Science.gov (United States)

    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

  16. Ionic-liquid-based proton conducting membranes for anhydrous H2/Cl2 fuel-cell applications.

    Science.gov (United States)

    Liu, Sa; Zhou, Li; Wang, Pengjie; Zhang, Fangfang; Yu, Shuchun; Shao, Zhigang; Yi, Baolian

    2014-03-12

    An ionic-liquid-doped poly(benzimidazole) (PBI) proton-conducting membrane for an anhydrous H2/Cl2 fuel cell has been proposed. Compared with other ionic liquids, such as imidazole-type ionic liquids, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]) showed better electrode reaction kinetics (H2 oxidation and Cl2 reduction reaction at platinum) and was more suitable for a H2/Cl2 fuel cell. PBI polymer and [dema][TfO] were compatible with each other, and the hybrid membranes exhibited high stability and good ionic conductivity, reaching 20.73 mS cm(-1) at 160 °C. We also analyzed the proton-transfer mechanism in this ionic-liquid-based membrane and considered that both proton-hopping and diffusion mechanisms existed. In addition, this composite electrolyte worked well in a H2/Cl2 fuel cell under non-water conditions. This work would give a good path to study the novel membranes for anhydrous H2/Cl2 fuel-cell application. PMID:24490850

  17. Influence of hole injection layer and work function of cathode on the performance of light-emitting liquid crystal cells with fluorescent dye-doped nematic liquid crystal

    Science.gov (United States)

    Honma, Michinori; Horiuchi, Takao; Watanabe, Kyoko; Nose, Toshiaki

    2014-11-01

    We investigated the properties of rubrene-doped nematic-liquid-crystal cells to help determine the appropriate structure and material of electrodes for inducing light emission. In particular, we addressed the influence of the insertion of a hole injection layer (HIL) and the work function of the cathode on device performance. As a result, the employment of a HIL and a lower-work-function material was revealed to be effective in obtaining higher luminance and external quantum efficiency. We concluded that this improvement is caused by the facilitated carrier injection on the HIL and cathode surface, as is true for common organic light-emitting diodes.

  18. Immersion and contact freezing experiments in the Mainz wind tunnel laboratory

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Osterberg, T; Wadsten, T

    1999-08-01

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

  20. Pressurized liquid extraction of Aglaonema sp. iminosugars: Chemical composition, bioactivity, cell viability and thermal stability.

    Science.gov (United States)

    Rodríguez-Sánchez, S; Martín-Ortiz, A; Carrero-Carralero, C; Ramos, S; Sanz, M L; Soria, A C

    2016-08-01

    Pressurized liquid extraction of Aglaonema sp. iminosugars has been optimized. A single cycle under optimal conditions (80mg, 100°C, 2min) was enough to extract ⩾96% of most iminosugars. Further incubation with Saccharomyces cerevisiae for 5h removed coextracted interfering low molecular weight carbohydrates from extracts of different Aglaonema cultivars. A complete characterization of these extracts was carried out by gas chromatography-mass spectrometry: three iminosugars were tentatively identified for the first time; α-homonojirimycin and 2,5-dideoxy-2,5-imino-d-mannitol were the major iminosugars determined. α-Glucosidase inhibition activity, cell viability and thermal stability of Aglaonema extracts were also evaluated. Extracts with IC50 for α-glucosidase activity in the 0.010-0.079mgmL(-1) range showed no decrease of Caco-2 cell viability at concentrations lower than 125μgmL(-1) and were stable at 50°C for 30days. These results highlight the potential of Aglaonema extracts as a source of bioactives to be used as functional ingredients.

  1. Direct methanol utilization in intermediate temperature liquid-tin anode solid oxide fuel cells

    International Nuclear Information System (INIS)

    Highlights: • Modification of Sn-based anode with Cu/SDC improves power density. • Cu and SDC improve wetting of Sn on YSZ and reduce anode polarization resistance. • Carbon formation has not been observed in SOFCs containing tin-based anodes. • Micro-channel structure in the anode reduces gas conversion resistance. - Abstract: Direct utilization of methanol in liquid tin anode solid oxide fuel cells has been experimentally demonstrated at 1023 K. A Cu and SDC modified Sn anode solid oxide fuel cell had a maximum power density of 259.2 mW/cm2 during operation on methanol. Carbon deposition was not observed in the Raman spectra of the post-test anodes. Electrochemical impedance spectroscopy indicated that gas conversion resistance increased when using methanol instead of hydrogen. The micro-channel architecture of the electrode mitigated the increase. Scanning electron microscopy images showed that addition of Cu and Sn improved wetting of Sn on YSZ and reduced anode polarization resistance. The anode gases were analyzed by mass spectroscopy and a mechanism for electrochemical oxidation of methanol has been proposed

  2. Energy harvesting from organic liquids in micro-sized microbial fuel cells

    KAUST Repository

    Mink, J.E.

    2014-03-07

    Micro-sized microbial fuel cells (MFCs) are miniature energy harvesters that use bacteria to convert biomass from liquids into usable power. The key challenge is transitioning laboratory test beds into devices capable of producing high power using readily available fuel sources. Here, we present a pragmatic step toward advancing MFC applications through the fabrication of a uniquely mobile and inexpensive micro-sized device that can be fueled with human saliva. The 25-ll MFC was fabricated with graphene, a two-dimensional atomic crystal-structured material, as an anode for efficient current generation and with an air cathode for enabling the use of the oxygen present in air, making its operation completely mobile and free of the need for laboratory chemicals. With saliva as a fuel, the device produced higher current densities (1190 Am-3) than any previous aircathode micro-sized MFCs. The use of the graphene anode generated 40 times more power than that possible using a carbon cloth anode. Additional tests were performed using acetate, a conventional organic material, at high organic loadings that were comparable to those in saliva, and the results demonstrated a linear relationship between the organic loading and current. These findings open the door to saliva-powered applications of this fuel cell technology for Lab-on-a-Chip devices or portable point-of-care diagnostic devices. 2014 Nature Publishing Group All rights reserved 1884-4057/14.

  3. A case study on stress preconditioning of a Lactobacillus strain prior to freeze-drying.

    Science.gov (United States)

    Bergenholtz, Åsa Schoug; Wessman, Per; Wuttke, Anne; Håkansson, Sebastian

    2012-06-01

    Freeze-drying of bacterial cells with retained viability and activity after storage requires appropriate formulation, i.e. mixing of physiologically adapted cell populations with suitable protective agents, and control of the freeze-drying process. Product manufacturing may alter the clinical effects of probiotics and it is essential to identify and understand possible factor co-dependencies during manufacturing. The physical solid-state behavior of the formulation and the freeze-drying parameters are critical for bacterial survival and thus process optimization is important, independent of strain. However, the maximum yield achievable is also strain-specific and strain survival is governed by e.g. medium, cell type, physiological state, excipients used, and process. The use of preferred compatible solutes for cross-protection of Lactobacilli during industrial manufacturing may be a natural step to introduce robustness, but knowledge is lacking on how compatible solutes, such as betaine, influence formulation properties and cell survival. This study characterized betaine formulations, with and without sucrose, and tested these with the model lactic acid bacteria Lactobacillus coryniformis Si3. Betaine alone did not act as a lyo-protectant and thus betaine import prior to freeze-drying should be avoided. Differences in protective agents were analyzed by calorimetry, which proved to be a suitable tool for evaluating the characteristics of the freeze-dried end products.

  4. The role of antioxidant system in freezing acclimation-induced freezing resistance of Populus suaveolens cuttings

    Institute of Scientific and Technical Information of China (English)

    Luo Lei; Lin Shan-zhi; Zheng Hui-quan; Lei Yang; Zhang Qian; Zhang Zhi-yi

    2007-01-01

    We investigated the changes in the contents of H2O2, malonaldehyde (MDA) and endogenous antioxidants, the activities of protective enzymes and some critical enzymes involved in the ascorbate-glutathione (ASA-GSH) cycle as well as freezing resistance(expressed as LT50) and correlations mentioned above, in detail using Populus suaveolens cuttings. The purpose was to explore the physiological mechanism of the enhancement of freezing resistance induced by freezing acclimation at -20℃, and to elucidate the physiological mechanisms by which trees adapt to freezing. The results showed that freezing acclimation enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), monodehydroascorbate reductase (MDAR), ascorbate peroxidase(APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR). And it increased the contents of reduced ascorbate(ASA), reduced glutathione (GSH), dehydroascorbate (DHA) and oxidized glutathione (GSSG). However, H2O2 and MDA contents and LT50 of cuttings were decreased. LT50 in cuttings was found to be closely correlated to the levels of SOD, POD, CAT, APX,DHAR, MDAR, GR, H2O2, MDA, ASA, GSH, DHA and GSSG during freezing acclimation. This suggested that the enhancement of freezing resistance of cuttings induced by freezing acclimation may relate to the distinct increase for the levels of SOD, POD, CAT,APX, DHAR, MDAR,GR,ASA, GSH, DHA, and GSSG. In addition, the observed levels of APX, DHAR, MDAR, GR, ASA, DHA,GSH and GSSG were higher than those of SOD, POD and CAT during freezing acclimation. It indicated that a higher capacity of the ASA-GSH cycle is required for H2O2 detoxification, and growth and development of cuttings. Based on the obtained results, it can be concluded that the ASA-GSH cycle plays an important role in enhancement of freezing resistance of P. suaveolens cuttings during freezing acclimation.

  5. Analysis of Different Freezing/Thawing Parameterizations using the UTOPIA Model

    Directory of Open Access Journals (Sweden)

    Claudio Cassardo

    2010-08-01

    Full Text Available Soil moisture changes are generally due to external factors (precipitation, evaporation, etc. and internal forces (gravitational force, capillarity, transpiration, etc.. When soil temperatures remain below 0 °C for a long time (hours or even entire consecutive days, part of the liquid water content of the soil can freeze, thus freezing/thawing effects must be taken into account in those conditions. The present work is devoted to the numerical modeling of the water phase change in the soil. The model used in this study for the land surface processes is UTOPIA (University of TOrino land Process Interaction in Atmosphere model, which is the updated version of LSPM (Land Surface Process Model. Scientific literature proposes some formulations to account for freezing/thawing processes. Three different parameterizations have been compared using a synthetic dataset in order to assess which one performs best from a physical point of view. Parameterizing freezing/thawing processes creates numerical instability and water overproduction in the UTOPIA model. These problems have been solved and described in the paper by means of synthetic data created to test the new parameterizations. The results show that UTOPIA is able to capture the freezing/thawing physical processes.

  6. Drying of α-amylase by spray drying and freeze-drying - a comparative study

    Directory of Open Access Journals (Sweden)

    S. S. de Jesus

    2014-09-01

    Full Text Available This study is aimed at comparing two traditional methods of drying of enzymes and at verifying the efficiency of each one and their advantages and disadvantages. The experiments were performed with a laboratory spray dryer and freeze-dryer using α-amylase as the model enzyme. An experimental design in star revealed that spray drying is mainly influenced by the inlet air temperature and feed flow rate, which were considered to be the main factors influencing the enzymatic activity and water activity; the long period of material exposure to high temperatures causes a partial activity loss. In the experiments of freeze drying, three methods of freezing were used (freezer, acetone and dry ice, and liquid nitrogen and samples subsequently freeze-dried for times ranging between 0-24 hours. The product obtained from the two techniques showed high enzymatic activity and low water activity. For the drying of heat-resistant enzymes, in which the product to be obtained does not have high added value, spray drying may be more economically viable because, in the freeze drying process, the process time can be considered as a limiting factor when choosing a technique.

  7. Freeze-drying behaviour of pasteurized whole egg

    International Nuclear Information System (INIS)

    Because it provides full nutritional and certain desirable functional attributes, egg products are widely used as ingredients in many food products. Dried egg is especially valuable for being stable, easily mixable and having a long shelf life. It is necessary to know the effects of drying conditions onto the moisture removal behaviour and the functional properties of the powder product, to serve the egg powder as an alternative. An experimental study was conducted to achieve an understanding of the freeze-drying behaviour of pasteurized whole egg having 24% dry solids. In order to determine the moisture removal behaviour; the percent moisture loss (w/w), the average moisture content and the drying rates were obtained, the drying curves were developed and total drying times were determined, also the movement of the dry-wet boundary between the frozen layer and the dry porous layer formed by sublimation of ice crystals were investigated during a complete process. The physical properties of pasteurized whole egg such as; colour, water activity (aw), the morphological structure (through SEM analysis) and functional properties (foam stability and dissolubility) were determined. The net colour change (ΔE) was about 22, independent of layer thickness. The water activity decreased to 0.22 at the end of drying. The SEM images of freeze-dried and slightly milled egg powder samples at magnification levels of 500 and 1000 showed the porous structure caused by sublimation of ice crystals generated within the egg structure during air blast freezing. The dissolubility and foaming capacity of powder egg were observed to be lower compared to those of pasteurized liquid egg. (author)

  8. Incompatibility of lyophilized inactivated polio vaccine with liquid pentavalent whole-cell-pertussis-containing vaccine.

    Science.gov (United States)

    Kraan, Heleen; Ten Have, Rimko; van der Maas, Larissa; Kersten, Gideon; Amorij, Jean-Pierre

    2016-08-31

    A hexavalent vaccine containing diphtheria toxoid, tetanus toxoid, whole cell pertussis, Haemophilius influenza type B, hepatitis B and inactivated polio vaccine (IPV) may: (i) increase the efficiency of vaccination campaigns, (ii) reduce the number of injections thereby reducing needlestick injuries, and (iii) ensure better protection against pertussis as compared to vaccines containing acellular pertussis antigens. An approach to obtain a hexavalent vaccine might be reconstituting lyophilized polio vaccine (IPV-LYO) with liquid pentavalent vaccine just before intramuscular delivery. The potential limitations of this approach were investigated including thermostability of IPV as measured by D-antigen ELISA and rat potency, the compatibility of fluid and lyophilized IPV in combination with thimerosal and thimerosal containing hexavalent vaccine. The rat potency of polio type 3 in IPV-LYO was 2 to 3-fold lower than standardized on the D-antigen content, suggesting an alteration of the polio type 3 D-antigen particle by lyophilization. Type 1 and 2 had unaffected antigenicity/immunogenicity ratios. Alteration of type 3 D-antigen could be detected by showing reduced thermostability at 45°C compared to type 3 in non-lyophilized liquid controls. Reconstituting IPV-LYO in the presence of thimerosal (TM) resulted in a fast temperature dependent loss of polio type 1-3 D-antigen. The presence of 0.005% TM reduced the D-antigen content by ∼20% (polio type 2/3) and ∼60% (polio type 1) in 6h at 25°C, which are WHO open vial policy conditions. At 37°C, D-antigen was diminished even faster, suggesting that very fast, i.e., immediately after preparation, intramuscular delivery of the conceived hexavalent vaccine would not be a feasible option. Use of the TM-scavenger, l-cysteine, to bind TM (or mercury containing TM degradation products), resulted in a hexavalent vaccine mixture in which polio D-antigen was more stable. PMID:27470209

  9. Physical degradation of membrane electrode assemblies undergoing freeze/thaw cycling: Diffusion media effects

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Soowhan; Mench, M.M. [Fuel Cell Dynamics and Diagnostics Laboratory, Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Research and Development Division, Hyundai Motor Company, Yongin 446-912 (Korea); Ahn, Byung Ki [Research and Development Division, Hyundai Motor Company, Yongin 446-912 (Korea)

    2008-04-15

    In this work, the effects of properties of diffusion media (DM) (stiffness, thickness and micro-porous layer (MPL)) on the physical damage of membrane electrode assembly (MEA) subjected to freeze/thaw cycling were studied. Pressure uniformity of the diffusion media onto the catalyst layer (CL) was determined to be a key parameter to mitigate freeze-induced physical damage. Stiffer diffusion media, enabling more uniform compression under the channels and lands, can mitigate surface cracks, but flexible cloth diffusion media experienced severe catalyst layer surface damage. The thickness of the diffusion media and existence of a micro-porous layer were not observed to be major factors to mitigate freeze-damage when the catalyst layer is in contact with liquid. Interfacial delamination between diffusion media and catalyst layers, but not between the catalyst layer and membrane, was observed. This permanent deformation of the stiff diffusion media in the channel locations as well as fractures of carbon fibers increased electrical resistance, and may increase water flooding, resulting in reduced longevity and operational losses. Although use of a freeze-tolerable MEA design (negligible virgin cracked catalyst layers with thinner reinforced membrane) [S. Kim, M.M. Mench, J. Power Sources, in press] with stiff diffusion media can reduce the freeze-damage in the worst case scenario test condition of direct liquid contact, extensive irreversible damage (diffusion media/catalyst layer interfacial delamination) was not completely prevented. In addition to proper material selection, liquid water contact with the catalyst layer should be removed prior to shutdown to a frozen state to permit long-term cycling damage and facilitate frozen start. (author)

  10. Monolayer freeze-fracture autoradiography: quantitative analysis of the transmembrane distribution of radioiodinated concanavalin A

    International Nuclear Information System (INIS)

    The technique of monolayer freeze-fracture autoradiography (MONOFARG) has been developed and the principles, quantitation, and application of the method are described. Cell monolayers attached to polylysine-treated glass were freeze-fractured, shadowed, and coated with dry, Parlodion-supported Ilford L4 photographic emulsion at room temperature. Quantitative aspects of MONOFARG were examined using radioiodinated test systems. Background was routinely -4 grains/μm2/day, the highest overall efficiency was between 25% and 45%, and grain density and efficiency were dependent on radiation dose for iodine-125 and D-19 development. Corrected grain densities were linearly proportional to iodine-125 concentration. The method was applied to an examination of the transmembrane distribution of radioiodinated and fluoresceinated concanavalin A (125I-FITC-Con-A). Human erythrocytes were labeled, column-purified, freeze-dried or freeze-fractured, autoradiographed, and examined by electron microscopy. The number of silver grains per square micrometer of unsplit single membrane was essentially identical to that of split extracellular membrane halves. These data demonstrate that 125I-FITC-Con-A partitions exclusively with the extracellular half of the membrane upon freeze-fracturing and can be used as a quantitative marker for the fraction of extracellular split membrane halves. This method should be able to provide new information about certain transmembrane properties of biological membrane molecules and probes, as well as about the process of freeze-fracture per se

  11. Amplitude Manipulation Evokes Upper Limb Freezing during Handwriting in Patients with Parkinson’s Disease with Freezing of Gait

    OpenAIRE

    Elke Heremans; Evelien Nackaerts; Griet Vervoort; Sarah Vercruysse; Sanne Broeder; Carolien Strouwen; Stephan P Swinnen; Alice Nieuwboer

    2015-01-01

    Background Recent studies show that besides freezing of gait (FOG), many people with Parkinson's disease (PD) also suffer from freezing in the upper limbs (FOUL). Up to now, it is unclear which task constraints provoke and explain upper limb freezing. Objective To investigate whether upper limb freezing and other kinematic abnormalities during writing are provoked by (i) gradual changes in amplitude or by (ii) sustained amplitude generation in patients with and without freezing of gait. Metho...

  12. Dynamics of leaf gas exchange, chlorophyll fluorescence and stem diameter changes during freezing and thawing of Scots pine seedlings.

    Science.gov (United States)

    Lindfors, Lauri; Hölttä, Teemu; Lintunen, Anna; Porcar-Castell, Albert; Nikinmaa, Eero; Juurola, Eija

    2015-12-01

    Boreal trees experience repeated freeze-thaw cycles annually. While freezing has been extensively studied in trees, the dynamic responses occurring during the freezing and thawing remain poorly understood. At freezing and thawing, rapid changes take place in the water relations of living cells in needles and in stem. While freezing is mostly limited to extracellular spaces, living cells dehydrate, shrink and their osmotic concentration increases. We studied how the freezing-thawing dynamics reflected on leaf gas exchange, chlorophyll fluorescence and xylem and living bark diameter changes of Scots pine (Pinus sylvestris L.) saplings in controlled experiments. Photosynthetic rate quickly declined following ice nucleation and extracellular freezing in xylem and needles, almost parallel to a rapid shrinking of xylem diameter, while that of living bark followed with a slightly longer delay. While xylem and living bark diameters responded well to decreasing temperature and water potential of ice, the relationship was less consistent in the case of increasing temperature. Xylem showed strong temporal swelling at thawing suggesting water movement from bark. After thawing xylem diameter recovered to a pre-freezing level but living bark remained shrunk. We found that freezing affected photosynthesis at multiple levels. The distinct dynamics of photosynthetic rate and stomatal conductance reveals that the decreased photosynthetic rate reflects impaired dark reactions rather than stomatal closure. Freezing also inhibited the capacity of the light reactions to dissipate excess energy as heat, via non-photochemical quenching, whereas photochemical quenching of excitation energy decreased gradually with temperature in agreement with the gas exchange data. PMID:26423334

  13. Investigation on improving characteristics of two-cell SBS system with CCl4/C2H5OH liquid mixture

    Institute of Scientific and Technical Information of China (English)

    Hasi Wu-Li-Ji; Lü Li-Qiang; He Wei-Ming

    2007-01-01

    In order to improve the performance of the two-cell stimulated Brillouin scattering(SBS) system,this paper proposes the methods of using mixtures,which require amplifier media to have small absorption rate,and generator media to have high optical breakdown threshold and Brillouin frequency shift equal to that of the amplification media.The characteristics of the two-cell SBS system are studied experimentally by using CCl4 as amplifier medium and CCl4,C2H5OH and CCl4/C2H5OH liquid mixture as generator medium pumped by Nd:YAG Q-switched laser.The obtained results show that liquid mixture in generator cell improves the power load ability,phase conjugation fidelity,energy reflectivity (ER) and ER stability.

  14. An Investigation of Freezing of Supercooled Water on Anti-Freeze Protein Modified Surfaces

    Institute of Scientific and Technical Information of China (English)

    Thibaut V J Charpentier; Anne Neville; Paul Millner; Rob Hewson; Ardian Morina

    2013-01-01

    This work investigates how functionalization ofaluminium surfaces with natural type Ⅲ Anti-Freeze Protein (AFP) affects the mechanism of heterogeneous ice nucleation.First the bulk ice nucleation properties of distilled water and aqueous solution of AFP were evaluated by differential scanning calorimetry.Then the modified surface was characterized by Secondary Ions Mass Spectroscopy (SIMS),Fourier Transform InfraRed (FTIR) spectroscopy and contact angle measurement.Freezing experiments were then conducted in which water droplets underwent a slow controlled cooling.This study shows that compared to uncoated aluminium,the anti-freeze proteins functionalized surfaces exhibit a higher and narrower range of freezing temperature.It was found that these proteins that keep living organisms from freezing in cold environment act in the opposite way once immobilized on surfaces by promoting ice nucleation.Some suggestions regarding the mechanism of action of the observed phenomena were proposed based on the Classical Nucleation Theory (CNT).

  15. Recycling of Indium From CIGS Photovoltaic Cells: Potential of Combining Acid-Resistant Nanofiltration with Liquid-Liquid Extraction.

    NARCIS (Netherlands)

    Zimmermann, Y.S.; Niewersch, C.; Lenz, M.; Corvini, P.F.X.; Schäffer, A.; Wintgens, T.

    2014-01-01

    Electronic consumer products such as smartphones, TV, computers, light-emitting diodes, and photovoltaic cells crucially depend on metals and metalloids. So-called “urban mining” considers them as secondary resources since they may contain precious elements at concentrations many times higher than t

  16. Effect of protective agents and previous acclimation on ethanol resistance of frozen and freeze-dried Lactobacillus plantarum strains.

    Science.gov (United States)

    Bravo-Ferrada, Bárbara Mercedes; Brizuela, Natalia; Gerbino, Esteban; Gómez-Zavaglia, Andrea; Semorile, Liliana; Tymczyszyn, E Elizabeth

    2015-12-01

    The aim of this work was to study the protective effect of sucrose, trehalose and glutamate during freezing and freeze-drying of three oenological Lactobacillus plantarum strains previously acclimated in the presence of ethanol. The efficiency of protective agents was assessed by analyses of membrane integrity and bacterial cultivability in a synthetic wine after the preservation processes. No significant differences in the cultivability, with respect to the controls cells, were observed after freezing at -80 °C and -20 °C, and pre-acclimated cells were more resistant to freeze-drying than non-acclimated ones. The results of multiparametric flow cytometry showed a significant level of membrane damage after freeze-drying in two of the three strains. The cultivability was determined after incubation in wine-like medium containing 13 or 14% v/v ethanol at 21 °C for 24 h and the results were interpreted using principal component analysis (PCA). Acclimation was the most important factor for preservation, increasing the bacterial resistance to ethanol after freezing and freeze-drying. Freeze-drying was the most drastic method of preservation, followed by freezing at -20 °C. The increase of ethanol concentration from 6 to 10% v/v in the acclimation medium improved the recovery of two of the three strains. In turn, the increase of ethanol content in the synthetic wine led to a dramatic decrease of viable cells in the three strains investigated. The results of this study indicate that a successful inoculation of dehydrated L. plantarum in wine depends not only on the use of protective agents, but also on the cell acclimation process prior to preservation, and on the ethanol content of wine.

  17. Female Fertility: Is it Safe to "Freeze?"

    Directory of Open Access Journals (Sweden)

    Lu Zhang

    2015-01-01

    Full Text Available Objective: To evaluate the safety and risk of cryopreservation in female fertility preservation. Data sources: The data analyzed in this review were the English articles from 1980 to 2013 from journal databases, primarily PubMed and Google scholar. The criteria used in the literature search show as following: (1 human; embryo; cryopreservation/freezing/vitrification, (2 human; oocyte/immature oocyte; cryopreservation/ freezing/vitrification, (3 human; ovarian tissue transplantation; cryopreservation/freezing/vitrification, (4 human; aneuploidy/DNA damage/epigenetic; cryopreservation/freezing/vitrification, and (5 human; fertility preservation; maternal age. Study selection: The risk ratios based on survival rate, maturation rate, fertilization rate, cleavage rate, implantation rate, pregnancy rate, and clinical risk rate were acquired from relevant meta-analysis studies. These studies included randomized controlled trials or studies with one of the primary outcome measures covering cryopreservation of human mature oocytes, embryos, and ovarian tissues within the last 7 years (from 2006 to 2013, since the pregnancy rates of oocyte vitrification were significantly increased due to the improved techniques. The data involving immature oocyte cryopreservation obtained from individual studies was also reviewed by the authors. Results: Vitrifications of mature oocytes and embryos obtained better clinical outcomes and did not increase the risks of DNA damage, spindle configuration, embryonic aneuploidy, and genomic imprinting as compared with fresh and slow-freezing procedures, respectively. Conclusions: Both embryo and oocyte vitrifications are safe applications in female fertility preservation.

  18. Identification and classification of genes required for tolerance to freeze-thaw stress revealed by genome-wide screening of Saccharomyces cerevisiae deletion strains.

    Science.gov (United States)

    Ando, Akira; Nakamura, Toshihide; Murata, Yoshinori; Takagi, Hiroshi; Shima, Jun

    2007-03-01

    Yeasts used in bread making are exposed to freeze-thaw stress during frozen-dough baking. To clarify the genes required for freeze-thaw tolerance, genome-wide screening was performed using the complete deletion strain collection of diploid Saccharomyces cerevisiae. The screening identified 58 gene deletions that conferred freeze-thaw sensitivity. These genes were then classified based on their cellular function and on the localization of their products. The results showed that the genes required for freeze-thaw tolerance were frequently involved in vacuole functions and cell wall biogenesis. The highest numbers of gene products were components of vacuolar H(+)-ATPase. Next, the cross-sensitivity of the freeze-thaw-sensitive mutants to oxidative stress and to cell wall stress was studied; both of these are environmental stresses closely related to freeze-thaw stress. The results showed that defects in the functions of vacuolar H(+)-ATPase conferred sensitivity to oxidative stress and to cell wall stress. In contrast, defects in gene products involved in cell wall assembly conferred sensitivity to cell wall stress but not to oxidative stress. Our results suggest the presence of at least two different mechanisms of freeze-thaw injury: oxidative stress generated during the freeze-thaw process, and defects in cell wall assembly. PMID:16989656

  19. Advances in Liquid Biopsy and its Clinical Application in the Diagnosis 
and Treatment of Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Difan ZHENG

    2016-06-01

    Full Text Available With the advances of technology, great progresses have been made in liquid biopsy in recent years. Liquid biopsy is currently playing a more and more important role in early diagnosis and treatment of cancer. Compared with traditional tissue biopsy, liquid biopsy is more popular in clinical practice due to its non-invasiveness, convenience and high repeatability. It has huge potential in the future. This review introduces circulating tumor cells (CTCs and circulating tumor DNA (ctDNA as the most important objects in liquid biopsy, mainly focusing on their history, biological characteristics, detection technologies, limitations and applications in non-small cell lung cancer.

  20. Fundamental emission characteristics of light-emitting liquid crystal cells with rubrene-doped 4-cyano-4'-pentylbiphenyl

    Science.gov (United States)

    Honma, Michinori; Horiuchi, Takao; Tanimoto, Masashi; Nose, Toshiaki

    2014-06-01

    We have investigated the light emission properties in rubrene-doped nematic liquid crystal (LC) cells from the following three standpoints: (i) effect of the heating temperature during the sample preparation, (ii) role of the emissive LC layer thickness, and (iii) role of different LC types used as the emissive layer. As a result, the light-emitting LC cells simultaneously exhibit the features of electrochemiluminescent cells (the carrier transport is governed by an ionic conduction) as well as of organic light-emitting diodes (the luminance strongly depends on the emissive layer thickness). Furthermore, we report that devices with cyano group containing LCs exhibit higher luminance compared to a fluorinated LC.

  1. 冷冻-解冻循环及气体吹扫对质子交换膜燃料电池的影响%Effects of Freeze/Thaw Cycles and Gas Purging Method on Polymer Electrolyte Membrane Fuel Cells

    Institute of Scientific and Technical Information of China (English)

    张生生; 俞红梅; 朱红; 侯俊波; 衣宝廉; 明平文

    2006-01-01

    At subzero temperature, the startup capability and performance of polymer electrolyte membrane fuel cell (PEMFC) deteriorates markedly. The object of this work is to study the degradation mechanism of key components of PEMFC-membrane-electrode assembly (MEA) and seek feasible measures to avoid degradation. The effect of freeze/thaw cycles on the structure of MEA is investigated based on porosity and SEM measurement. The performance of a single cell was also tested before and after repetitious freeze/thaw cycles. The experimental results indicated that the performance of a PEMFC decreased along with the total operating time as well as the pore size distribution shifting and micro configuration changing. However, when the redundant water had been removed by gas purging, the performance of the PEMFC stack was almost resumed when it experienced again the same subzero temperature test. These results show that it is necessary to remove the water in PEMFCs to maintain stable performance under subzero temperature and gas purging is proved to be the effective operation.

  2. Blazed vector grating liquid crystal cells with photocrosslinkable polymeric alignment films fabricated by one-step polarizer rotation method

    Science.gov (United States)

    Kawai, Kotaro; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2014-12-01

    Blazed vector grating liquid crystal (LC) cells, in which the directors of low-molar-mass LCs are antisymmetrically distributed, were fabricated by one-step exposure of an empty glass cell inner-coated with a photocrosslinkable polymer LC (PCLC) to UV light. By adopting a LC cell structure, twisted nematic (TN) and homogeneous (HOMO) alignments were obtained in the blazed vector grating LC cells. Moreover, the diffraction efficiency of the blazed vector grating LC cells was greatly improved by increasing the thickness of the device in comparison with that of a blazed vector grating with a thin film structure obtained in our previous study. In addition, the diffraction efficiency and polarization states of ±1st-order diffracted beams from the resultant blazed vector grating LC cells were controlled by designing a blazed pattern in the alignment films, and these diffraction properties were well explained on the basis of Jones calculus and the elastic continuum theory of nematic LCs.

  3. The weakening of cell protection as a result of the Chernobyl NPP accident recovery factors affect on liquidator's organism

    International Nuclear Information System (INIS)

    The markers of oxidative stress as well as intracellular antioxidants (enzymatic and non- enzymatic) were studied in 100 Chernobyl accident recovery workers(liquidators). Hormone screening tests were carried out in 250 liquidators. All persons (mean age - 35 years) have got external irradiation dose from 2 to 30 cGr. Control group was selected from persons of same age having not participated in accident liquidation. The significant antioxidant imbalance was found. ROS inactivating enzymes deficiency was revealed in neutrofils, lymphocytes and alveolar macrophages (AM). For instance, superoxide dismutase(SOD) activity in liquidator's AM was 2,8±0,3 U/mg protein (4,1-±1,8 U/mg protein in controls, P<0,05). Catalase activity was also lower than in control group (P<0,05). The significant disorder of the thiol-disulfide turnover was revealed: depression of reduced glutathione by 1,71-±0,46 μmol/l (control: 3,15±-0,34 μtmol/l, P<0,05). The oxidative stress destructive action realized in the conditions of excessive production of ROS, while the antioxidant potential was diminished(P<0,05). The oxidative destruction of lipids and proteins was found to be induced by free radical action. TBARS level in alveolar macrophages of liquidators was more than three times higher compared to controls. Enhanced levels of protein carbonyl groups were found as well. The decrease of TT3 in liquidators was detected most frequently. In 19% liquidators examined, TT3 was below the reference value (0,8 ng/ml). The TT3 level was registered at the low limit of the reference range (0,8 ng/ml) in 18% of liquidators. ''Low T3'' syndrome may be considered as a cell protection weakening. All the cellular protective mechanisms take part in processes of DNA synthesis and repair, transcription and translation, cell respiration and metabolism. Significant impairment of the cellular protective systems in liquidators could be regarded as a base of persistent ''chromosomal pathology'' and imbalance of

  4. Freeze tolerance of soil chytrids from temperate climates in Australia.

    Science.gov (United States)

    Gleason, Frank H; Letcher, Peter M; McGee, Peter A

    2008-08-01

    Very little is known about the capacity of soil chytrids to withstand freezing in the field. Tolerance to freezing was tested in 21 chytrids isolated from cropping and undisturbed soils in temperate Australia. Samples of thalli grown on peptone-yeast-glucose (PYG) agar were incubated for seven days at -15 degrees C. Recovery of growth after thawing and transferring to fresh medium at 20 degrees C indicated survival. All isolates in the Blastocladiales and Spizellomycetales survived freezing in all tests. All isolates in the Chytridiales also survived freezing in some tests. None of the isolates in the Rhizophydiales survived freezing in any of the tests. However, some isolates in the Rhizophydiales recovered growth after freezing if they were grown on PYG agar supplemented with either 1% sodium chloride or 1% glycerol prior to freezing. After freezing, the morphology of the thalli of all isolates was observed under LM. In those isolates that recovered growth after transfer to fresh media, mature zoosporangia were observed in the monocentric isolates and resistant sporangia or resting spores in the polycentric isolates. Encysted zoospores in some monocentric isolates also survived freezing. In some of the experiments the freezing and thawing process caused visible structural damage to the thalli. The production of zoospores after freezing and thawing was also used as an indicator of freeze tolerance. The chytrids in this study responded differently to freezing. These data add significantly to our limited knowledge of freeze tolerance in chytrids but leave many questions unanswered. PMID:18550351

  5. Nanosize Copper Dispersed Ionic Liquids As an Electrolyte of New Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Fu-Lin Chen

    2009-01-01

    Full Text Available To enhance the electrical conductivity of the electrolyte for a newly developed dye-sensitized solar cell (DSSC, metallic copper (Cu encapsulated within the carbon shell (Cu@C nanoparticles dispersed in a room temperature ionic liquid (RTIL (e.g., [bmim+][PF6−] has been studied in the present work. By the pulsed-field gradient spin-echo NMR method, the self-diffusion coefficients of cations and anions of the RTIL have been determined. The self-diffusion coefficient of the [bmim+] cations in the RTIL dispersed with 0.08% of Cu@C nanoparticles is increased by 35%. The electrical conductivity of the Cu@C dispersed RTIL is also increased by 65% (1.0 → 2.3 ms/cm. It is very clear the nanosize Cu@C dispersed RTIL with a relatively greater diffusion coefficient and electrical conductivity can be a very effective electrolyte especially utilized in DSSCs.

  6. Simple improvement in freeze-tolerance of bakers' yeast with poly-gamma-glutamate.

    Science.gov (United States)

    Yokoigawa, Kumio; Sato, Machiko; Soda, Kenji

    2006-09-01

    We examined the effect of poly-gamma-glutamate (PGA) on the freeze-tolerance of four types of commercial bakers' yeast (freeze-tolerant, osmotic-tolerant, low-temperature-sensitive, and ordinary bakers' yeasts). The survival ratio of ordinary bakers' yeast cells frozen at -30 degrees C for 3 d in a medium (0.5% yeast extract, 0.5% peptone, and 2% glucose: YPD medium) was improved by adding more than 1% PGA to the medium; the survival ratio increased from about 10% to more than 70%. All PGA preparations, which differed in average molecular mass (50, 2,000, 4,000, 6,000, 8,000, and 10,000 kDa), showed a similar cryoprotecive effect on the cells. Similar results were also obtained with other types of bakers' yeast, sake yeast and beer yeast. When the four types of bakers' yeast cell were frozen at -30 degrees C for 3 d in dough supplemented with more than 1% PGA, the cells (after freezing and thawing) showed higher leavening ability than those frozen in dough without PGA, irrespective of the molecular mass of PGA. Thus, PGA appears to protect bakers' yeast from lethal freeze injury, leading to a high leavening ability after freezing and thawing. PGA did not decrease the original leavening ability of the bakers' yeast, and was not decomposed by the yeast cells. PGA suppressed the decrease in leavening ability during a prolonged fermentation time, probably because PGA adsorbed inhibitory metabolites accumulated in the dough. PGA could prove useful for improving the freeze-tolerance of bakers' yeast by its addition to dough. PMID:17046536

  7. Heat transfer coefficient of cryotop during freezing.

    Science.gov (United States)

    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).

  8. Freezing precipitation in Russia and the Ukraine

    Directory of Open Access Journals (Sweden)

    A. A. Zavyalova

    2007-04-01

    Full Text Available Conditions for freezing precipitation (FP, including freezing rain (FR and freezing drizzle (FZ for 8 airports in Russia and 4 in the Ukraine are studied on the basis of 10 to 20-year series of surface observations, radiosonde and objective analysis data. Statistical characteristics are presented of the FP episode durations and of occurrence frequency dependences on surface air temperature, wind direction and speed and cloud base height. From the radiosonde data, it is found that the "classical mechanism" of FP generation (for which, stratification of "warm nose" type in the cloud layer is necessary is not frequent: most of FP cases are associated with "all cold" conditions in the lower 3-km layer, that is, with negative temperatures in and below the clouds.

  9. Prediction of the acoustic and bubble fields in insonified freeze-drying vials.

    Science.gov (United States)

    Louisnard, O; Cogné, C; Labouret, S; Montes-Quiroz, W; Peczalski, R; Baillon, F; Espitalier, F

    2015-09-01

    The acoustic field and the location of cavitation bubble are computed in vials used for freeze-drying, insonified from the bottom by a vibrating plate. The calculations rely on a nonlinear model of sound propagation in a cavitating liquid [Louisnard, Ultrason. Sonochem., 19, (2012) 56-65]. Both the vibration amplitude and the liquid level in the vial are parametrically varied. For low liquid levels, a threshold amplitude is required to form a cavitation zone at the bottom of the vial. For increasing vibration amplitudes, the bubble field slightly thickens but remains at the vial bottom, and the acoustic field saturates, which cannot be captured by linear acoustics. On the other hand, increasing the liquid level may promote the formation of a secondary bubble structure near the glass wall, a few centimeters below the free liquid surface. These predictions suggest that rather complex acoustic fields and bubble structures can arise even in such small volumes. As the acoustic and bubble fields govern ice nucleation during the freezing step, the final crystal's size distribution in the frozen product may crucially depend on the liquid level in the vial. PMID:25800984

  10. Synthesis and Characterization of a Gel-Type Electrolyte with Ionic Liquid Added for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Le-Yan Shi

    2013-01-01

    Full Text Available This study intends to develop the electrolyte needed in dye-sensitized solar cells (DSSCs. Moreover, three different ionic liquids in different molalities are added to the gel-type electrolyte. Experimental results show that the DSSC composed of the gel-type electrolyte with no ionic liquid added can acquire 4.13% photoelectric conversion efficiency. However, the DSSC composed of the gel-type electrolyte with 0.4 M of 1-butyl-3-methylimidazolium chloride added has an open-circuit voltage of 810 mV, a short-circuit current density of 9.56 mA/cm2, and photoelectric conversion efficiency reaching 4.89%. Comparing this DSSC with the DSSC with no ionic liquid added, the photoelectric conversion efficiency can be enhanced by 18.4%. As to durability, the DSSC composed of the gel-type electrolyte with ionic liquid added still has a photoelectric conversion efficiency of 3.28% on the 7th day after it is stored in an enclosed space and maintains 0.72% efficiency on the 14th day. When the proposed DSSC is compared with the DSSC prepared by using a liquid-type electrolyte, the durability of its photoelectric conversion efficiency can be increased by 7 times.

  11. Flash and smash: rapid freezing of muscle fibers activated by photolysis of caged ATP.

    OpenAIRE

    Hirose, K.; Lenart, T D; Murray, J.M.; Franzini-Armstrong, C; Goldman, Y E

    1993-01-01

    A new approach was used to study transient structural states of cross-bridges during activation of muscle fibers. Rabbit skinned muscle fibers were rapidly and synchronously activated from the rigor state by photolysis of caged ATP in the presence of Ca2+. At several different times during the switch from rigor to fully active tension development, the fibers were rapidly frozen on a liquid helium-cooled metal block, freeze-substituted, and examined in an electron microscope. The limits of str...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-01-29

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

  13. PLUGM: a coupled thermal-hydraulic computer model for freezing melt flow in a channel

    International Nuclear Information System (INIS)

    PLUGM is a coupled thermal-hydraulic computer model for freezing liquid flow and plugging in a cold channel. PLUGM is being developed at Sandia National Laboratories for applications in Sandia's ex-vessel Core Retention Concept Assessment Program and in Sandia's LMFBR Transition Phase Program. The purpose of this paper is to introduce PLUGM and demonstrate how it can be used in the analysis of two of the core retention concepts under investigation at Sandia: refractory brick crucibles and particle beds

  14. Hatchling turtles survive freezing during winter hibernation.

    OpenAIRE

    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 ...

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

    International Nuclear Information System (INIS)

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

  16. A high-throughput method to measure the sensitivity of yeast cells to genotoxic agents in liquid cultures.

    Science.gov (United States)

    Toussaint, Martin; Levasseur, Geneviève; Gervais-Bird, Julien; Wellinger, Raymund J; Elela, Sherif Abou; Conconi, Antonio

    2006-07-14

    The sensitivity of yeast Saccharomyces cerevisiae to DNA damaging agents is better represented when cells are grown in liquid media than on solid plates. However, systematic assessment of several strains that are grown in different conditions is a cumbersome undertaking. We report an assay to determine cell growth based on automatic measurements of optical densities of very small (100 microl) liquid cell cultures. Furthermore, an algorithm was elaborated to analyze large data files obtained from the cell growth curves, which are described by the growth rate--that starts at zero and accelerates to the maximal rate (mu(m))--and by the lag time (lambda). Cell dilution spot test for colony formation on solid media and the growth curve assay were used in parallel to analyze the phenotypes of cells after treatments with three different classes of DNA damaging agents (methyl methanesulfonate, bleomycin, and ultraviolet light). In these experiments the survival of the WT (wild type) and a number of DNA repair-deficient strains were compared. The results show that only the cell growth curve assay could uncover subtle phenotypes when WT cells, or mutant strains that are only weakly affected in DNA repair proficiency, were treated with low doses of cytotoxic compounds. The growth curve assay was also applied to establish whether histone acetyltransferases and deacetylases affect the resistance of yeast cells to UV irradiation. Out of 20 strains tested the sir2delta and rpd3delta cells were found to be more resistant than the WT, while gcn5delta and spt10delta cells were found to be more sensitive. This new protocol is sensitive, provides quantifiable data, offers increased screening capability and speed compared to the colony formation test. PMID:16713735

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

    Science.gov (United States)

    Larson, Don J; Barnes, Brian M

    2016-01-01

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

  18. Multi-scale validation of a new soil freezing scheme for a land-surface model with physically-based hydrology

    Directory of Open Access Journals (Sweden)

    I. Gouttevin

    2011-08-01

    Full Text Available Soil freezing is a major feature of boreal regions with substantial impact on climate. The present paper describes the implementation of the thermal and hydrological effects of soil freezing in the land surface model ORCHIDEE, which includes a physical description of continental hydrology. The new soil freezing scheme is evaluated against analytical solutions and in-situ observations at a variety of scales in order to test its numerical robustness, explore its sensitivity to parameterization choices and confront its performances to field measurements at typical application scales.

    It is shown that the appropriate vertical discretization to represent the thermal freezing dynamics is centimetric, and the appropriate freezing window is 1 to 2 °C wide. Furthermore, linear and thermodynamical parameterizations of the liquid water content lead to similar results in terms of water redistribution within the soil as a consequence of freezing.

    The new soil freezing scheme considerably improves the representation of runoff and river discharge in regions underlain by permafrost and subject to seasonal freezing. A thermodynamical parameterization of the liquid water content appears more appropriate for an integrated description of the hydrological processes at the scale of the vast Siberian basins. The use of a subgrid variability approach and the representation of wetlands could help capturing the features of the Arctic hydrological regime with more accuracy.

    The modelling of the soil thermal regime is generally improved by the representation of soil freezing processes. In particular, the dynamics of the active layer is captured with an increased accuracy by the soil freezing module, which is of crucial importance in the prospect of simulations involving the response of frozen carbon stocks to future warming. A realistic simulation of the snow cover and its thermal properties, as well as the representation of an organic horizon

  19. Suppressive effects of liquid crystal compounds on the growth of U937 human leukemic monocyte lymphoma cells

    Directory of Open Access Journals (Sweden)

    Ishikawa Junya

    2012-02-01

    Full Text Available Abstract Background The aim of this study was to evaluate the biological and pharmaceutical activities of 14 amphiphilic liquid-crystalline compounds (LCs, i.e, phenylpyrimidine derivatives possessing D-glucamine and cyanobiphenyl derivatives with a terminal hydroxyl unit. Results The cytotoxic properties of the LCs on the cell growth, cell cycle distribution, and cell signaling pathway of U937 human leukemic monocyte lymphoma cells were assessed by flow cytometry and western blot analysis. Some LCs showed cytostatic effects, suppressing cell growth via S-phase arrest and without apoptosis in U937 cells. To investigate the mechanisms of the LC-induced S-phase arrest, proteins relevant to cell cycle regulation were investigated by western blot analysis. The rate of LC-induced S-phase arrest was congruent with the decreased expression of MCM2, cyclin A, cyclin B, CDK2, phospho-CDK1 and Cdc25C. Observed changes in cell cycle distribution by LC treated might be caused by insufficient preparation for G2/M transition. Considering the structure of the LCs, the rod-like molecules displaying cytotoxicity against U937 cells possessed flexible spacers with no bulky polar group attached via the flexible spacer. Conclusions Our results revealed that some LCs showed cytotoxic properties against non-solid type tumor human leukemic cells via LC-induced S-phase arrest and decreasing expression of several cell cycle related proteins.

  20. Farinose flavonoids are associated with high freezing tolerance in fairy primrose (Primula malacoides) plants.

    Science.gov (United States)

    Isshiki, Ryutaro; Galis, Ivan; Tanakamaru, Shigemi

    2014-02-01

    The deposition of surface (farinose) flavonoids on aerial parts of some Primula species is a well-documented but poorly understood phenomenon. Here, we show that flavonoid deposition on the leaves and winter buds may contribute strongly to preventing freezing damage in these plants. The ice nucleation temperature of fairy primrose (Primula malacoides) leaves covered with natural flavone was approximately 6 °C lower compared to those that had their flavone artificially removed. Additionally, farinose flavonoids on the leaves reduced subsequent electrolyte leakage (EL) from the cells exposed to freezing temperatures. Interestingly, exogenous application of flavone at 4 mg/g fresh weight to P. malacoides leaves, which had the original flavone mechanically removed, restored freezing tolerance, and diminished EL from the cells to pretreatment values. Our results suggest that farinose flavonoids may function as mediators of freezing tolerance in P. malacoides, and exogenous application of flavone could be used to reduce freezing damage during sudden but predictable frost events in other plant species.

  1. Using Peltier Cells to Study Solid-Liquid-Vapour Transitions and Supercooling

    Science.gov (United States)

    Torzo, Giacomo; Soletta, Isabella; Branca, Mario

    2007-01-01

    We propose an apparatus for teaching experimental thermodynamics in undergraduate introductory courses, using thermoelectric modules and a real-time data acquisition system. The device may be made at low cost, still providing an easy approach to the investigation of liquid-solid and liquid-vapour phase transitions and of metastable states…

  2. Collective dynamics of water in the living cell and in bulk liquid. New physical models and biologcial infereneces

    CERN Document Server

    Preoteasa, Eugen A

    2008-01-01

    In the frame of collective dynamics in water, models built on elementary excitations and long-range electromagnetic interactions in the cell and bulk liquid are presented. Making use of the low effective mass of water coherence domains (CDs), we examined the relevance of simple quantum models to cellular characteristics. A hypothesis of CDs Bose-type condensation, and models of CD in spherical wells with impenetrable and semipenetrable walls, and of an isotropic oscillator consisting of two interacting CDs were investigated. Estimated cellular volumes matched to medium-sized bacteria and small prokaryotes, and to some organelles in eukaryotic cells. Also, the cytotoxic effects of heavy water in eukaryotes were explained. In another approach we proposed a plasmon-like model of hydrogen-oxygen ionic plasma in liquid water. In addition to plasmonic oscillations, the model predicted sound-like non-equilibrium elementary excitations that we called densitons (the sound anomaly of water), the vaporization heat and t...

  3. Fast fringe-field switching of a liquid crystal cell by two-dimensional confinement with virtual walls

    Science.gov (United States)

    Choi, Tae-Hoon; Oh, Seung-Won; Park, Young-Jin; Choi, Yeongyu; Yoon, Tae-Hoon

    2016-06-01

    We report a simple method for reducing the response time of a fringe-field switching liquid crystal cell by using two-dimensional confinement of the liquid crystals. Through both numerical calculations and experiments, we show that the switching speed can be increased by several fold in a fringe-field switching cell by simply using a rubbing angle of zero, which causes virtual walls to be built when an electric field is applied between the interdigitated electrodes and the common electrode, without requiring additional fabrication steps or complicated drive schemes. Furthermore, the devices fabricated with this method exhibit a reduced color shift and excellent dynamic stability, even with a high applied voltage and under external pressure.

  4. Investigation of Freeze and Thaw Cycles of a Gas-Charged Heat Pipe

    Science.gov (United States)

    Ku, Jentung; Ottenstein, Laura; Krimchansky, Alexander

    2012-01-01

    The traditional constant conductance heat pipes (CCHPs) currently used on most spacecraft run the risk of bursting the pipe when the working fluid is frozen and later thawed. One method to avoid pipe bursting is to use a gas-charged heat pipe (GCHP) that can sustain repeated freeze/thaw cycles. The construction of the GCHP is similar to that of the traditional CCHP except that a small amount of non-condensable gas (NCG) is introduced and a small length is added to the CCHP condenser to serve as the NCG reservoir. During the normal operation, the NCG is mostly confined to the reservoir, and the GCHP functions as a passive variable conductance heat pipe (VCHP). When the liquid begins to freeze in the condenser section, the NCG will expand to fill the central core of the heat pipe, and ice will be formed only in the grooves located on the inner surface of the heat pipe in a controlled fashion. The ice will not bridge the diameter of the heat pipe, thus avoiding the risk of pipe bursting during freeze/thaw cycles. A GCHP using ammonia as the working fluid was fabricated and then tested inside a thermal vacuum chamber. The GCHP demonstrated a heat transport capability of more than 200W at 298K as designed. Twenty-seven freeze/thaw cycles were conducted under various conditions where the evaporator temperature ranged from 163K to 253K and the condenser/reservoir temperatures ranged from 123K to 173K. In all tests, the GCHP restarted without any problem with heat loads between 10W and 100W. No performance degradation was noticed after 27 freeze/thaw cycles. The ability of the GCHP to sustain repeated freeze/thaw cycles was thus successfully demonstrated.

  5. Readily restoring freeze-dried probilosomes as potential nanocarriers for enhancing oral delivery of cyclosporine A.

    Science.gov (United States)

    Guan, Peipei; Lu, Yi; Qi, Jianping; Wu, Wei

    2016-08-01

    Formulating vesicular nanocarriers into dried precursors so as to overcome the drawbacks associated with liquid formulations is challengeable due to low efficiency of restoration. In this study, bilosomes interiorly thickened with gelatin (G-BLs) was evaluated for the ability to withstand freeze-drying stress and enhanced oral bioavailability of a model drug, cyclosporine A (CyA). The restoration efficiency of freeze-dried pro-G-BLs is investigated by comparing the particle size distribution, entrapment efficiency and morphology of the bilosomes before and after freeze-drying. Particle size and polydispersity index (PI) of pro-G-BLs after restoration was similar to that before freeze-drying, whereas freeze-dried bilosomes without gelatin thickening (pro-BLs) show irreversible damage and aggregation along with significantly increased particle size and PI after restoration. Entrapment efficiency of pro-G-BLs remains as high as 83.7%, in sharp contrast with 66.7% for pro-BLs. Pharmacokinetics in beagle dogs show improved absorption of CyA in pro-G-BLs as compared to pro-BLs, G-BLs and microemulsion-based Sandimmun Neoral(®). The relative oral bioavailability of CyA-loaded pro-G-BLs, pro-BLs and G-BLs was 165.2%, 123.5% and 130.1%, respectively, with Neoral(®) as the reference. It is concluded that interior thickening with gelatin significantly enhanced the stability against freeze-drying stress, which as a result improves the restoring efficiency and oral bioavailability. PMID:27085046

  6. Investigation of the Freeze-Lining Formed in an Industrial Copper Converting Calcium Ferrite Slag

    Science.gov (United States)

    Fallah-Mehrjardi, Ata; Jansson, Jani; Taskinen, Pekka; Hayes, Peter C.; Jak, Evgueni

    2014-06-01

    Pyrometallurgical coppermaking processes are operated under intensive reaction conditions; high process temperatures and vigorous bath agitation is used to increase the kinetics of reactions and to achieve high smelter throughput. Slag freeze-lining reactor wall protection is a widely used technology in coppermaking processes, such as flash smelting and converting reactors. Freeze-linings mitigate and resist the effects of thermal and chemical attack by aggressive slags. In this laboratory-based study, a water-cooled probe "cold finger" technique has been used to investigate freeze-lining formation with calcium ferrite slags in equilibrium with metallic copper; the slag composition reflects that used in the industrial copper flash converting furnace of Rio Tinto—Kennecott Utah Copper. The effects of probe immersion times on the thickness and microstructures in the freeze-lining deposits have been investigated. A range of complex oxide solutions and copper-containing phases have been found in the deposits. The phase assemblages formed from the industrial calcium ferrite slag in the steady-state deposit are very complex and information on the phase equilibria of the multi-component systems with addition of minor elements may not be available. Subsolidus and subliquidus phase equilibria in the Cu-Ca-Fe-O system at metallic copper saturation along with interpolated temperature across the deposit, microstructural changes and compositional trends in the phases in the deposit have been used to understand the formation and characteristics of the phases in the steady-state freeze-lining. Also, it has been shown that under steady-state conditions a dense sealing layer consisting primarily of the spinel primary phase is formed at the deposit/liquid interface; however, the interface temperature is below the liquidus temperature. The findings of the study have potentially important implications for the operation of the converting furnace and the design of freeze linings in

  7. Impact of aerosol and freezing level on orographic clouds: A sensitivity study

    Science.gov (United States)

    Xiao, Hui; Yin, Yan; Chen, Qian; Zhao, Pengguo

    2016-07-01

    The response of clouds and precipitation to changes in aerosol properties is variable with the ambient meteorological conditions, which is important for the distribution of water resources, especially in mountain regions. In this study, a detailed bin microphysics scheme is coupled into the Weather Research and Forecasting (WRF) model to investigate how orographic clouds and precipitation respond to changes in aerosols under different thermodynamic profiles. The model results suggest that when the initial aerosol number concentration changes from a clean continental background (4679 cm- 3) to a polluted urban environment (23,600 cm- 3), the accumulated surface precipitation amount can be increased up to 14% mainly due to the enhanced riming process which results from more droplets of 10-30 μm in diameter. When the freezing level is lowered from 2.85 km to 0.9 km (above 1000 hPa level), the growth of ice-phase particles via riming process is enhanced, leading to more precipitation. However, the response of surface precipitation amount to increase in aerosol particle concentration is not linear with lowering freezing level, and there is a maximum precipitation enhancement caused by aerosols (about 14%) as the freezing level is at 1.4 km. Further sensitivity tests show that, the response of riming growth to increase in aerosol particle concentration becomes more significant with lowering the freezing level, but this effect becomes less significant as the freezing level is further lowered due to the limited liquid water. Moreover, the growth of raindrops through collision and coalescence is suppressed with lowering freezing level, due to the shorter distance between the melting level and the ground.

  8. Collective dynamics of water in the living cell and in bulk liquid. New physical models and biological inferences

    OpenAIRE

    Preoteasa, Eugen A.; Apostol, Marian V.

    2008-01-01

    In the frame of collective dynamics in water, models built on elementary excitations and long-range electromagnetic interactions in the cell and bulk liquid are presented. Making use of the low effective mass of water coherence domains (CDs), we examined the relevance of simple quantum models to cellular characteristics. A hypothesis of CDs Bose-type condensation, and models of CD in spherical wells with impenetrable and semipenetrable walls, and of an isotropic oscillator consisting of two i...

  9. A Review on Current Status of Stability and Knowledge on Liquid Electrolyte-Based Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Frédéric Sauvage

    2014-01-01

    Full Text Available The purpose of this review is to gather the current background in materials development and provide the reader with an accurate image of today’s knowledge regarding the stability of dye-sensitized solar cells. This contribution highlights the literature from the 1970s to the present day on nanostructured TiO2, dye, Pt counter electrode, and liquid electrolyte for which this review is focused on.

  10. Building the Method to Determine the Rate of Freezing Water in Penaeus monodon of the Freezing Process

    Directory of Open Access Journals (Sweden)

    Nguyen Tan Dzung

    2012-10-01

    Full Text Available The method of determination the rate of freezing water in Penaeus monodon of freezing process was established on base the equation of energy balance in warming up process Penaeus monodon after freezing to determine specific heat of Penaeus monodon. The result obtained was built the mathematical model (19 to determine the rate of freezing water according to the freezing temperature of Penaeus monodon. The results indicated that when water was completely frozen (ω = 1 or 100%, the optimal freezing temperature of Penaeus monodon was-22.00°C.

  11. Mass production of shaped particles through vortex ring freezing

    Science.gov (United States)

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

    2016-08-01

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

  12. Demonstration of an Electrochemical Liquid Cell for Operando Transmission Electron Microscopy Observation of the Lithiation/Delithiation Behavior of Si Nanowire Battery Anodes

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Meng [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Parent, Lucas R. [Univ. of California, Davis, CA (United States); Mehdi, Beata L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Unocic, Raymond R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); McDowell, Matthew T. [Stanford Univ., CA (United States); Sacci, Robert L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Xu, Wu [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Connell, Justin G. [Northwestern Univ., Evanston, IL (United States); Xu, Pinghong [Univ. of California, Davis, CA (United States); Abellan Baeza, Patricia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Chen, Xilin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zhang, Yaohui [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Harbin Inst. of Technology (China); Perea, Daniel E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Evans, James E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lauhon, Lincoln [Northwestern Univ., Evanston, IL (United States); Zhang, Jiguang [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Liu, Jun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Browning, Nigel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cui, Yi [Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States); Arslan, Ilke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wang, Chong M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-11-13

    Over the last few years, in-situ transmission electron microscopy (TEM) studies of lithium ion batteries using an open-cell configuration have helped us to gain fundamental insights into the structural and chemical evolution of the electrode materials in real time. In the standard open-cell configuration, the electrolyte is either solid lithium oxide or an ionic liquid, which is point-contacted with the electrode. This cell design is inherently different from a real battery, where liquid electrolyte forms conformal contact with electrode materials. The knowledge learnt from open cells can deviate significantly from the real battery, calling for operando TEM technique with conformal liquid electrolyte contact. In this paper, we developed an operando TEM electrochemical liquid cell to meet this need, providing the configuration of a real battery and in a relevant liquid electrolyte. To demonstrate this novel technique, we studied the lithiation/delithiation behavior of single Si nanowires. Some of lithiation/delithation behaviors of Si obtained using the liquid-cell are consistent with the results from the open-cell studies. However, we also discovered new insights different from the open cell configuration - the dynamics of the electrolyte and, potentially, a future quantitative characterization of the SEI layer formation and structural and chemical evolution.

  13. In situ liquid-cell electron microscopy of silver-palladium galvanic replacement reactions on silver nanoparticles

    Science.gov (United States)

    Sutter, E.; Jungjohann, K.; Bliznakov, S.; Courty, A.; Maisonhaute, E.; Tenney, S.; Sutter, P.

    2014-09-01

    Galvanic replacement reactions provide an elegant way of transforming solid nanoparticles into complex hollow morphologies. Conventionally, galvanic replacement is studied by stopping the reaction at different stages and characterizing the products ex situ. In situ observations by liquid-cell electron microscopy can provide insight into mechanisms, rates and possible modifications of galvanic replacement reactions in the native solution environment. Here we use liquid-cell electron microscopy to investigate galvanic replacement reactions between silver nanoparticle templates and aqueous palladium salt solutions. Our in situ observations follow the transformation of the silver nanoparticles into hollow silver-palladium nanostructures. While the silver-palladium nanocages have morphologies similar to those obtained in ex situ control experiments the reaction rates are much higher, indicating that the electron beam strongly affects the galvanic-type process in the liquid-cell. By using scavengers added to the aqueous solution we identify the role of radicals generated via radiolysis by high-energy electrons in modifying galvanic reactions.

  14. Effect of tumor antigen released during photodynamic therapy or freezing-thawing on the maturation phenotypes of dendritic cells%光动力治疗和冻融对肿瘤细胞抗原释放及树突细胞成熟表型的影响

    Institute of Scientific and Technical Information of China (English)

    江珊; 夏育民; 程丹; 程鸿

    2011-01-01

    目的 探讨光动力疗法(PDT)和冻融导致的肿瘤细胞抗原暴露,对体外树突细胞(DC)成熟表型的影响.方法 对体外培养的4T1乳腺癌细胞分别予以PDT和反复冻融,检测4T1细胞的坏死与凋亡,收获上清液并与未成熟DC(imDC)或成熟DC(mDC)共同孵育,采用流式细胞法和激光共聚焦显微镜分析DC免疫表型和形态学特征.结果 经两种机制处理的4T1细胞都以坏死为主,但PDT较冻融诱导更高的凋亡率(34.7%±9.6%比16.8%±5.1%,P<0.05);与上清液孵育后,PDT组imDC的CD80、CD86与I-A/I-E阳性率分别为22.4%±4.6%、22.5%±5.6%、24.3%±6.3%,冻融组依次为17.3%±3.3%、18.0%±4.7%、20.7%±3.1%,均高于空白对照组(14.2%±3.0%、13.6%±3.3%、15.5%±2.1%,P<0.05),且PDT组升高更明显,而mDC的免疫表型变化差异无统计学意义(P>0.05).结论 与冻融相比较,PDT导致更高的细胞凋亡率,更易诱导imDC表达成熟表型.%Objective To investigate the effects of tumor antigen on the maturation phenotypes of dendritic cells through different treatments of antigenic exposure. Methods The necrosis and apoptosis of 4T1 mammary carcinoma cells were detected after an in vitro treatment of photodynamic therapy (PDT) or freezing-thawing. The supernatant of 4T1 cells was harvested and added into the culture of immature or mature dendritic cells (DCs). The immune phenotypes and morphological features of DCs were analyzed by flow cytometry and confocal laser scanning microscopy respectively. Results Necrosis predominated after these treatments. But the apoptotic ratio was higher in PDT cells than that in freezing-thawing cells (34. 7% ±9. 6% vs 16. 8% ± 5. 1%, P < 0.05 ). After co-culturing with different supernatants, the immature DCs of PDT group showed more significant increases of positive rates of CD80 (22. 4% ±4. 6% ),CD86 (22. 5% ± 5. 6% ) and I-A/I-E (24. 3% ± 6. 3% ) versus the immature DCs of freezing-thawing group (17.3% ±3.3%, 18.0% ±4.7% and

  15. Effects of Female Sex Hormones on Susceptibility to HSV-2 in Vaginal Cells Grown in Air-Liquid Interface.

    Science.gov (United States)

    Lee, Yung; Dizzell, Sara E; Leung, Vivian; Nazli, Aisha; Zahoor, Muhammad A; Fichorova, Raina N; Kaushic, Charu

    2016-01-01

    The lower female reproductive tract (FRT) is comprised of the cervix and vagina, surfaces that are continuously exposed to a variety of commensal and pathogenic organisms. Sexually transmitted viruses, such as herpes simplex virus type 2 (HSV-2), have to traverse the mucosal epithelial lining of the FRT to establish infection. The majority of current culture systems that model the host-pathogen interactions in the mucosal epithelium have limitations in simulating physiological conditions as they employ a liquid-liquid interface (LLI), in which both apical and basolateral surfaces are submerged in growth medium. We designed the current study to simulate in vivo conditions by growing an immortalized vaginal epithelial cell line (Vk2/E6E7) in culture with an air-liquid interface (ALI) and examined the effects of female sex hormones on their growth, differentiation, and susceptibility to HSV-2 under these conditions, in comparison to LLI cultures. ALI conditions induced Vk2/E6E7 cells to grow into multi-layered cultures compared to the monolayers present in LLI conditions. Vk2 cells in ALI showed higher production of cytokeratin in the presence of estradiol (E2), compared to cells grown in progesterone (P4). Cells grown under ALI conditions were exposed to HSV-2-green fluorescent protein (GFP) and the highest infection and replication was observed in the presence of P4. Altogether, this study suggests that ALI cultures more closely simulate the in vivo conditions of the FRT compared to the conventional LLI cultures. Furthermore, under these conditions P4 was found to confer higher susceptibility to HSV-2 infection in vaginal cells. The vaginal ALI culture system offers a better alternative to study host-pathogen interactions. PMID:27589787

  16. Freeze-thaw induced gelation of alginates.

    Science.gov (United States)

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

    2016-09-01

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

  17. Scaling-Up Eutectic Freeze Crystallization

    NARCIS (Netherlands)

    Genceli, F.E.

    2008-01-01

    A novel crystallization technology, Eutectic Freeze Crystallization (EFC) has been investigated and further developed in this thesis work. EFC operates around the eutectic temperature and composition of aqueous solutions and can be used for recovery of (valuable) dissolved salts (and/or or acids) an

  18. Freezing in the Antarctic limpet, Nacella concinna.

    Science.gov (United States)

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

    2010-08-01

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

  19. Freeze-thaw induced gelation of alginates.

    Science.gov (United States)

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

    2016-09-01

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

  20. Anomalous freezing behavior of nanoscale liposomes

    DEFF Research Database (Denmark)

    Spangler, E. J.; Kumar, P. B. S.; Laradji, M.

    2012-01-01

    The effect of the finite size of one-component liposomes on their phase behavior is investigated via simulations of an implicit-solvent model of self-assembled lipid bilayers. We found that the high curvature of nanoscale liposomes has a significant effect on their freezing behavior. While...

  1. Combined X-Ray and fully leaky guided mode studies of the smectic layer and optic tensor configuration in a ferroelectric liquid-crystal cell.

    Science.gov (United States)

    Hodder, B; Sambles, J R; Jenkins, S; Richardson, R M

    2000-10-01

    X-ray scattering together with optical characterization using fully leaky guided modes have been used for the first time to study the same ferroelectric liquid-crystal cell. This enables direct calculation of an accurate cone and chevron description of the liquid-crystal director profile since the layer structure and optic tensor configuration are both well known. PMID:11019296

  2. Exploring the heterogeneous interfaces in organic or ruthenium dye-sensitized liquid- and solid-state solar cells.

    Science.gov (United States)

    Kwon, Young Soo; Song, Inwoo; Lim, Jong Chul; Song, In Young; Siva, Ayyanar; Park, Taiho

    2012-06-27

    The interfacial properties were systematically investigated using an organic sensitizer (3-(5'-{4-[(4-tert-butyl-phenyl)-p-tolyl-amino]-phenyl}-[2,2']bithiophenyl-5-yl)-2-cyano-acrylic acid (D)) and inorganic sensitizer (bis(tetrabutylammonium) cis-bis(thiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylato) ruthenium(II) (N719)) in a liquid-state and a solid-state dye-sensitized solar cell (DSC). For liquid-DSCs, the faster charge recombination for the surface of D-sensitized TiO2 resulted in shorter diffusion length (LD) of ∼3.9 μm than that of N719 (∼7.5 μm), limiting the solar cell performance at thicker films used in liquid-DSCs. On the other hand, for solid-DSCs using thin TiO2 films (∼ 2 μm), D-sensitized device outperforms the N719-sensitized device in an identical fabrication condition, mainly due to less perfect wetting ability of solid hole conductor into the porous TiO2 network, inducing the dye monolayer act as an insulation layer, while liquid electrolyte is able to fully wet the surface of TiO2. Such insulation effect was attributed to the fact that the significant increase in recombination resistance (from 865 to 4,400 Ω/cm(2)) but shorter electron lifetime (from 10.8 to 0.8 ms) when compared to liquid-DSCs. Higher recombination resistance for solid-DSCs induced the electron transport-limited situation, showing poor performance of N719-sensitized device which has shorter electron transport time and similar LD (2.9 μm) with D-sensitized device (3.0 μm). PMID:22658859

  3. Osteogenesis and vascularization of bone marrow mesenchymal stem cells transfected by pcDNA3/hVEGF165 combined with freeze-dried cancellous bone in vivo%脂质体介导pcDNA3/hVEGF165转染骨髓基质干细胞复合冻干骨的体内成骨和血管化

    Institute of Scientific and Technical Information of China (English)

    张鹏; 董玲; 杨连甲

    2011-01-01

    BACKGROUND: Previous studies have shown that vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) can improve the implant livability and growth.OBJECTIVE: To study the effect of freeze-dried cancellous bone on the osteogenesis and vascularization of bone marrow stem cells transfected with pcDNA3/hVEGF165 in vivo.METHODS: The rabbit bone marrow stem cells, which were transfected with pcDNA3/hVEGF165 by liposome mediated method and then adhered to freeze-dried cancellous bone, were implanted in the muscle pouches of rabbits. The rabbits were divided into three groups: freeze-dried cancellous bone group (A group), freeze-dried cancellous bone combined with bone marrow stem cells group (B group), freeze-dried cancellous bone combined with bone marrow stem cells transfected with VEGF group (C group).RESULTS AND CONCLUSION: At the 8th week after implantation, it was found, compared with A group and B group, C group grew a large number of osteoblasts, osteoclasts and cartilage, and the number of vessels in C group was more than that in A or B group. The osteogenesis of the freeze-dried cancellous bone combined with bone marrow stem cells transfected with VEGF using pcDNA3/hVEGF165 by liposome mediated method is better than the freeze-dried cancellous bone or freeze-dried cancellous bone combined with bone marrow stem cells.%背景:以往的研究表明血管内皮生长因子、碱性成纤维细胞生长因子可以促进移植物的存活和体内生长.目的:观察脂质体介导的pcDNA3/hVEGF165转染骨髓基质干细胞后复合冻干松质骨在体内的成骨和血管化效果.方法:取同种异体新西兰大白兔的耾骨和股骨制备冻干骨,用脂质体将血管内皮生长因子转染入体外培养扩增新西兰大白兔骨髓基质干细胞中,使其附着于同种异体冻干松质骨.将新西兰大白兔分为3组,于兔竖脊肌分别植入单纯冻干骨、单纯骨髓间充质干细胞复合冻干骨组、转染

  4. Efficiency Enhancement of Dye-Sensitized Solar Cells: Using Salt CuI as an Additive in an Ionic Liquid

    Institute of Scientific and Technical Information of China (English)

    CHEN Lie-Hang; XUE Bo-Fei; LIU Xi-Zhe; LI Ke-Xin; LUO Yan-Hong; MENG Qing-Bo; WANG Rui-Lin; CHEN Li-Quan

    2007-01-01

    Energy conversion efficiency of the dye-sensitized solar cell is improved from 3.5% to 4.5% by adding a small amount of CuI into an ionic liquid electrolyte. It is found that other copper-I salts, for example, CuBr, have the same effect for the dye-sensitized solar cell. Experimental results show that no Cu2+ ions exist in this electrolyte.It is suggested that this improvement is caused by the adsorption of Cu+ onto the TiO2 porous film.

  5. Role of Liquid-based Cytology and Cell Block in the Diagnosis of Endometrial Lesions

    Institute of Scientific and Technical Information of China (English)

    Hui Zhang; Jia Wen; Pi-Li Xu; Rui Chen; Xi Yang; Lian-Er Zhou; Ping Jiang

    2016-01-01

    Background:Liquid-based cytology (LBC) offers an altemative method to biopsy in screening endometrial cancer.Cell block (CB),prepared by collecting residual cytological specimen,represents a novel method to supplement the diagnosis of endometrial cytology.This study aimed to compare the specimen adequacy and diagnostic accuracy of LBC and CB in the diagnosis of endometrial lesions.Methods:A total of 198 women with high risks of endometrial carcinoma (EC) from May 2014 to April 2015 were enrolled in this study.The cytological specimens were collected by the endometrial sampler (SAP-1) followed by histopathologic evaluation of dilatation and curettage or biopsy guided by hysteroscopy.The residual cytological specimens were processed into paraffin-embedded CB after LBC preparation.Diagnostic accuracies of LBC and CB for detecting endometrial lesions were correlated with histological diagnoses.Chi-square test was used to compare the specimen adequacies of LBC and CB.Results:The specimen inadequate rate of CB was significantly higher than that of LBC (22.2% versus 7.1%,P < 0.01).There were 144 cases with adequate specimens for LBC and CB preparation.Among them,29 cases were atypical endometrial hyperplasia (11 cases) or carcinoma (18 cases) confirmed by histology evaluation.Taking atypical hyperplasia and carcinoma as positive,the diagnostic accuracy of CB was 95.1% while it was 93.8% in LBC.When combined LBC with CB,the diagnostic accuracy was improved to 95.8%,with a sensitivity of 89.7% and specificity of 97.4%.Conclusions:CB is a feasible and reproducible adjuvant method for screening endometrial lesions.A combination of CB and LBC can improve the diagnostic accuracy of endometrial lesions.

  6. Freezing characteristics and texture variation after freezing and thawing of four fruit types

    Directory of Open Access Journals (Sweden)

    Arpassorn Sirijariyawat

    2012-11-01

    Full Text Available One major problem with frozen fruits is a loss of texture. Therefore this study investigated the effects of the freezingprocess on the freezing profiles, texture, and drip loss of apple, mango, cantaloupe, and pineapple fruit samples. All frozenthawedfruits varied in these three properties because of diversity in the fresh fruits. Mango had the highest total solublesolids content and the lowest freezing point, whereas pineapple showed the highest freezing rate. The highest firmness andcrunchy texture were found in fresh apple, and these properties were absent in the other fresh fruits. The firmness of allfrozen fruits significantly decreased by different percentages as compared to those of the fresh fruits. The drip loss of eachfruit type was also significantly different with apple samples having the highest firmness decrease and drip loss. This studyshows that freezing characteristics and frozen fruit properties depend on type of fruit.

  7. Female Fertility: Is it Safe to "Freeze?"

    Institute of Scientific and Technical Information of China (English)

    Lu Zhang; Li-Ying Yan; Xu Zhi; Jie Yan; Jie Qiao

    2015-01-01

    Objective:To evaluate the safety and risk of cryopreservation in female fertility preservation.Data sources:The data analyzed in this review were the English articles from 1980 to 2013 from journal databases,primarily PubMed and Google scholar.The criteria used in the literature search show as following:(1) human; embryo; cryopreservation/freezing/vitrification,(2) human; oocyte/immature oocyte; cryopreservation/freezing/vitrification,(3) human; ovarian tissue transplantation; cryopreservation/ freezing/vitrification,(4) human; aneuploidy/DNA damage/epigenetic; cryopreservation/freezing/vitrification,and (5) human; fertility preservation; maternal age.Study selection:The risk ratios based on survival rate,maturation rate,fertilization rate,cleavage rate,implantation rate,pregnancy rate,and clinical risk rate were acquired from relevant meta-analysis studies.These studies included randomized controlled trials or studies with one of the primary outcome measures covering cryopreservation of human mature oocytes,embryos,and ovarian tissues within the last 7 years (from 2006 to 2013,since the pregnancy rates of oocyte vitrification were significantly increased due to the improved techniques).The data involving immature oocyte cryopreservation obtained from individual studies was also reviewed by the authors.Results:Vitrifications of mature oocytes and embryos obtained better clinical outcomes and did not increase the risks of DNA damage,spindle configuration,embryonic aneuploidy,and genomic imprinting as compared with fresh and slow-freezing procedures,respectively.Conclusions:Both embryo and oocyte vitrifications are safe applications in female fertility preservation.

  8. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses

    Energy Technology Data Exchange (ETDEWEB)

    Huang Yi; Song Lei; Liu Xiaoguang; Xiao Yanfeng; Wu Yao; Chen Jiyong; Wu Fang; Gu Zhongwei, E-mail: fangwu0808@yahoo.co, E-mail: fwu@scu.edu.c [National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064 (China)

    2010-12-15

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 {mu}m and an average porosity of 48.26 {+-} 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  9. Hydroxyapatite coatings deposited by liquid precursor plasma spraying: controlled dense and porous microstructures and osteoblastic cell responses

    International Nuclear Information System (INIS)

    Hydroxyapatite coatings were deposited on Ti-6Al-4V substrates by a novel plasma spraying process, the liquid precursor plasma spraying (LPPS) process. X-ray diffraction results showed that the coatings obtained by the LPPS process were mainly composed of hydroxyapatite. The LPPS process also showed excellent control on the coating microstructure, and both nearly fully dense and highly porous hydroxyapatite coatings were obtained by simply adjusting the solid content of the hydroxyapatite liquid precursor. Scanning electron microscope observations indicated that the porous hydroxyapatite coatings had pore size in the range of 10-200 μm and an average porosity of 48.26 ± 0.10%. The osteoblastic cell responses to the dense and porous hydroxyapatite coatings were evaluated with human osteoblastic cell MG-63, in respect of the cell morphology, proliferation and differentiation, with the hydroxyapatite coatings deposited by the atmospheric plasma spraying (APS) process as control. The cell experiment results indicated that the heat-treated LPPS coatings with a porous structure showed the best cell proliferation and differentiation among all the hydroxyapatite coatings. Our results suggest that the LPPS process is a promising plasma spraying technique for fabricating hydroxyapatite coatings with a controllable microstructure, which has great potential in bone repair and replacement applications.

  10. Modeling efficiency and water balance in PEM fuel cell systems with liquid fuel processing and hydrogen membranes

    Science.gov (United States)

    Pearlman, Joshua B.; Bhargav, Atul; Shields, Eric B.; Jackson, Gregory S.; Hearn, Patrick L.

    Integrating PEM fuel cells effectively with liquid hydrocarbon reforming requires careful system analysis to assess trade-offs associated with H 2 production, purification, and overall water balance. To this end, a model of a PEM fuel cell system integrated with an autothermal reformer for liquid hydrocarbon fuels (modeled as C 12H 23) and with H 2 purification in a water-gas-shift/membrane reactor is developed to do iterative calculations for mass, species, and energy balances at a component and system level. The model evaluates system efficiency with parasitic loads (from compressors, pumps, and cooling fans), system water balance, and component operating temperatures/pressures. Model results for a 5-kW fuel cell generator show that with state-of-the-art PEM fuel cell polarization curves, thermal efficiencies >30% can be achieved when power densities are low enough for operating voltages >0.72 V per cell. Efficiency can be increased by operating the reformer at steam-to-carbon ratios as high as constraints related to stable reactor temperatures allow. Decreasing ambient temperature improves system water balance and increases efficiency through parasitic load reduction. The baseline configuration studied herein sustained water balance for ambient temperatures ≤35 °C at full power and ≤44 °C at half power with efficiencies approaching ∼27 and ∼30%, respectively.

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

    Science.gov (United States)

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

    2016-01-01

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

  12. 7 CFR 58.620 - Freezing and packaging rooms.

    Science.gov (United States)

    2010-01-01

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

  13. COMPREHENSIVE DESIGN METHOD OF FREEZE WALL AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    CHENXiangsheng

    1995-01-01

    Artificially ground freezing (AGF) is one of the main methods to establish temporary support for shaft sinking in unstable water bearing strata. Domke(1915) formula based on frozen soil strength has widely been used for designing freeze wall thickness. However, it can not ensure the stability of freeze wall, nor guarantee the safety of shaft construction as frozen depth increase in unstable water bearing strata. F.A.Auld (1985, 1988) presented a design method of freeze wall, which is on the basis of strength and stability, together with deformation of freeze wall.He combined deformation of freeze wall, lining and deformation of freeze tube to set up a comprehensive design method for freeze wall. This paper, according to the practice in China, describes a comprehensive design method for deep freeze wall, considering influence of excavation rate of advance, unsupported length of freeze wall and the sump state on inward deformation of freeze wall, and the allowable pipe deformation caused by inward deformation of freeze wall. Finally, successful application of this method to the large scale coal mine-Jining No.2 Mine in Shandong Province of China, is presented.It saved much investment compared with F.A.Auld's design for the same mine on behalf of Shell Coal International.

  14. Genetics of winter wheat response to two freezing treatments

    Science.gov (United States)

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

  15. Ribosome binding sites visualized on freeze-fractured membranes of the rough endoplasmic reticulum

    OpenAIRE

    1980-01-01

    Freeze-fracture micrographs of cells of the green alga Micrasterias denticulata stabilized by ultrarapid freezing reveal imprints of polysomes on the rough endoplasmic reticulum membranes. The imprints appear as broad, spiral ridges on the P faces and as corresponding wide grooves on the E faces of the membranes. Distinct 110-A particles with a spacing of 270 +/- 45 A are associated with the P-face ridges. Where imprints of individual ribosomes can be discerned, it is seen that there is a 1:1...

  16. Investigation of Freeze-Linings in Copper-Containing Slag Systems: Part I. Preliminary Experiments

    Science.gov (United States)

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

    2013-06-01

    Slag freeze-linings are increasingly used in industrial pyrometallurgical processes to insure that furnace integrity is maintained in aggressive high-temperature environments. Most previous studies of freeze-linings have analyzed the formation of slag deposits based solely on heat-transfer models. The focus of the present research is to determine the impact of slag chemistry and local process conditions on the microstructures, thickness, stability, and heat-transfer characteristics of the frozen deposit at steady-state conditions. The formation of the freeze-linings is studied under controlled laboratory conditions using an air-cooled "cold-finger" technique for Cu-Fe-Si-Al-O slag at equilibrium with metallic copper relevant to the industrial copper smelting processes. The phase assemblages and microstructures of the deposits formed in the cold-finger experiments differ significantly from those expected from phase equilibrium considerations. The freeze-lining deposits have been found, in general, to consist of several layers. Starting from the cold finger, these layers consist of glass; glass with microcrystalline precipitates; closed crystalline layer; and open crystalline layer. Even at steady-state conditions, there was no primary phase sealing layer of delafossite [Cu2O · (Al, Fe)2O3] present at the deposit/liquid interface—these observations differ markedly from those expected from phase equilibrium considerations. The findings have significant practical implications, and potential for the improved design and operation of industrial metallurgical furnaces.

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

    Science.gov (United States)

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

    2016-07-01

    Ice nucleating particles (INPs) in the atmosphere are responsible for glaciating cloud droplets between 237 and 273 K. Different mechanisms of heterogeneous ice nucleation can compete under mixed-phase cloud conditions. Contact freezing is considered relevant because higher ice nucleation temperatures than for immersion freezing for the same INPs were observed. It has limitations because its efficiency depends on the number of collisions between cloud droplets and INPs. To date, direct comparisons of contact and immersion freezing with the same INP, for similar residence times and concentrations, are lacking. This study compares immersion and contact freezing efficiencies of three different INPs. The contact freezing data were obtained with the ETH CoLlision Ice Nucleation CHamber (CLINCH) using 80 µm diameter droplets, which can interact with INPs for residence times of 2 and 4 s in the chamber. The contact freezing efficiency was calculated by estimating the number of collisions between droplets and particles. Theoretical formulations of collision efficiencies gave too high freezing efficiencies for all investigated INPs, namely AgI particles with 200 nm electrical mobility diameter, 400 and 800 nm diameter Arizona Test Dust (ATD) and kaolinite particles. Comparison of freezing efficiencies by contact and immersion freezing is therefore limited by the accuracy of collision efficiencies. The concentration of particles was 1000 cm-3 for ATD and kaolinite and 500, 1000, 2000 and 5000 cm-3 for AgI. For concentrations nucleation process that is enhanced compared to immersion freezing due to the position of the INP on the droplet, and we discriminate it from collisional contact freezing, which assumes an enhancement due to the collision of the particle with the droplet. For best comparison with contact freezing results, immersion freezing experiments of the same INPs were performed with the continuous flow diffusion chamber Immersion Mode Cooling chAmber-Zurich Ice

  18. Potential role of salicylic acid in modulating diacylglycerol homeostasis in response to freezing temperatures in Arabidopsis.

    Science.gov (United States)

    Tan, Wei-Juan; Xiao, Shi; Chen, Qin-Fang

    2015-01-01

    In our recent article in Molecular Plant, we reported that 3 lipase-like defense regulators SENESCENCE-ASSOCIATED GENE101 (SAG101), ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4) are involved in the regulation of freezing tolerance in Arabidopsis. The transcripts of SAG101, EDS1 and PAD4 were inducible by cold stress and their knockout or knockdown mutants exhibited enhanced chilling and freezing tolerance in comparison to the wild type. The freezing tolerance phenotype showed in the sag101, eds1 and pad4 mutants was correlated with the transcriptional upregulation of C-REPEAT/DRE BINDING FACTORs (CBFs) and their regulons as well as increased levels of proline. Upon cold exposure, the sag101, eds1 and pad4 mutants showed ameliorated cell death and accumulation of hydrogen peroxide, which were highly induced by freezing stress in the wild-type leaves. Moreover, the contents of salicylic acid (SA) and diacylglycerol (DAG) were significantly decreased in the sag101, eds1 and pad4 mutants compared to the wild type. Taken together, our results suggest that the SAG101, EDS1 and PAD4 are negative regulators in the freezing response and function, at least in part, by modulating the homeostasis of SA and DAG in Arabidopsis.

  19. Effects of GDL structure with an efficient approach to the management of liquid water in PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kimball, Erin E.; Benziger, Jay B.; Kevrekidis, Yannis G. [Department of Chemical Engineering Princeton University, Princeton, NJ 08544 (United States)

    2010-08-15

    A model fuel cell with a single transparent straight flow channel and segmented anode was constructed to measure the direct correlation of liquid water movement with the local currents along the flow channel. Water drops emerge through the largest pores of the GDL with the size of the droplets that emerge on the surface determined by the size of the pore and its location under the gas flow channel or under the land. Gravity, surface tension, and the shearing force from the gas flow control the movement of liquid in the gas flow channel. By creating a single large diameter pore in the GDL (gas diffusion layer), liquid water flow emergent from the GDL was forced to be in specific locations along the length of the channel and either under the land or under the channel. The effects of gravity were amplified when the large pore was under the channel, but diminished with the large pore under the land. Current fluctuations were minimised when the dominant water transport from the GDL pore was near the cathode outlet. The results show that it is possible to engineer the water distribution in PEM fuel cells by modifying the pore sizes in the GDL. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  20. Research on preparing instant phytase by using freeze-drying method%冷冻干燥法制备速溶植酸酶的研究

    Institute of Scientific and Technical Information of China (English)

    马俊孝; 刘伟; 史衍鲁

    2011-01-01

    采用毕赤酵母发酵制备酶液,膜超滤浓缩、硫酸铵盐析法沉淀酶蛋白,结合冷冻干燥法制得速溶型植酸酶.结果表明,对酶活力达19 500 U/ml的发酵液进行浓缩后,以70%饱和度的硫酸铵进行盐析,分离后的酶蛋白经过冷冻干燥得到活力为500 000 U/g的植酸酶,速溶性好,溶解后清亮透明.酶的冻干粉50 ℃保存90 d内酶活力仍能维持96%以上的活力.为高酶活速溶植酸酶的工业化生产提供了一条可行的思路.%The freeze-drying technology for producing instant phytase was studied. The crude preparation was obtained by Pichia pastoris high cell density fermentation, microporous membrane ultrafiltration,ammonium sulfate precipitation and freeze-drying. Fermentation liquid, activity achieved 19 500 U/ml,was managed by ultrafiltration membrane, concentrated with ammonium sulphate in 70% saturation. After freeze-drying, the final product was obtained with up to 500 000 U/g. The preparation could soluble in water quickly with no turbidity, no precipitation and good transparency. The powder remained over 96%of its activity under 50 ℃ within 90 days. Our studies provide a feasible method for preparing instant phytase with higher activity.

  1. MICROSTRUCTURE MODIFICATIONS INDUCED IN SPRUCE WOOD BY FREEZING

    Directory of Open Access Journals (Sweden)

    Maria Bernadett SZMUTKU

    2011-12-01

    Full Text Available Scanning Electron Microscopy (SEM is amodern, non-invasive method for objective andspecialized image analysis of anatomical materialfeatures at microscopic level. Referring to wood, itoffers the possibility to view in 3D a bunch ofneighboring cells, in all three grain directions.This allows the imaging of modifications thatmight appear in the structure of the wood cellmembrane (e.g. micro-fissures caused by differentfactors, including temperature variations. This paperpresents the results of the SEM analysis performedon European spruce (Picea abies samples, cut fromboards which were subjected to freezing and thawingunder different conditions of temperature variationand time of exposure.The main aim of this research was to reveal theconditions which determine the occurrence of microfissuresin the cell wall and consequently lead tostrength losses in wood.

  2. Numerical Study of Liquid Sloshing on Anti-sloshing Device Using Open Cell Metal Foams in Oil Tank

    Science.gov (United States)

    Zhang, Y.; Qu, Z. G.; Tao, W. Q.; Lu, T. J.

    2010-03-01

    A new baffle structure design named open-cell metal foams baffle for anti-sloshing device in oil tank is presented in this study. Numerical simulation study on the liquid sloshing with various baffles is carried out using FLUENT with the volume-of-fluid (VOF) model. Four types of baffles were studied, namely non-baffle (type A), conventional parallel-baffle (type B), cross-baffle (type C) and open- cell metal foams baffles (type D). The oil velocity distribution, centroid and oil occupancy in the sloshing process is revealed in the case of vehicle speeding up and turning respectively. It is found that type D reduce velocity of oil, increase the value of oil occupancy in the suction pipe entrance of the oil tank and lower the centroid of oil obviously comparing with the other types. As for the same open-cell metal foam pore density, lower open-cell metal foam porosity has much better effect of inhibition of liquid sloshing, but there is little deviation among different porosity for the absolute value. Moreover, according to the same porosity, the oil centroid can be lowered obviously with the increase of pore density. The results of type D show practical significance and referable guideline for baffles design to improve the safety and stability of vehicle.

  3. Freezing Tolerance of Bulb Scales of Lily Cultivars : Effects of Freezing and Storage Duration and Partial Dehydration

    NARCIS (Netherlands)

    Bonnier, Frans J.M.; Jansen, Ritsert C.; Tuyl, Jaap M. van

    1997-01-01

    Effects of freezing duration, previous storage duration of bulbs at -2 °C, and partial dehydration of scales on freezing tolerance of lily (Lilium hybrids) scales were studied for a series of cultivars. Freezing tolerance of scales was estimated by measuring ion leakage and recording scale bulblet r

  4. High ice nucleation activity located in blueberry stem bark is linked to primary freeze initiation and adaptive freezing behaviour of the bark.

    Science.gov (United States)

    Kishimoto, Tadashi; Yamazaki, Hideyuki; Saruwatari, Atsushi; Murakawa, Hiroki; Sekozawa, Yoshihiko; Kuchitsu, Kazuyuki; Price, William S; Ishikawa, Masaya

    2014-01-01

    Controlled ice nucleation is an important mechanism in cold-hardy plant tissues for avoiding excessive supercooling of the protoplasm, for inducing extracellular freezing and/or for accommodating ice crystals in specific tissues. To understand its nature, it is necessary to characterize the ice nucleation activity (INA), defined as the ability of a tissue to induce heterogeneous ice nucleation. Few studies have addressed the precise localization of INA in wintering plant tissues in respect of its function. For this purpose, we recently revised a test tube INA assay and examined INA in various tissues of over 600 species. Extremely high levels of INA (-1 to -4 °C) in two wintering blueberry cultivars of contrasting freezing tolerance were found. Their INA was much greater than in other cold-hardy species and was found to be evenly distributed along the stems of the current year's growth. Concentrations of active ice nuclei in the stem were estimated from quantitative analyses. Stem INA was localized mainly in the bark while the xylem and pith had much lower INA. Bark INA was located mostly in the cell wall fraction (cell walls and intercellular structural components). Intracellular fractions had much less INA. Some cultivar differences were identified. The results corresponded closely with the intrinsic freezing behaviour (extracellular freezing) of the bark, icicle accumulation in the bark and initial ice nucleation in the stem under dry surface conditions. Stem INA was resistant to various antimicrobial treatments. These properties and specific localization imply that high INA in blueberry stems is of intrinsic origin and contributes to the spontaneous initiation of freezing in extracellular spaces of the bark by acting as a subfreezing temperature sensor. PMID:25082142

  5. The freezing and supercooling of garlic (Allium sativum L.)

    Energy Technology Data Exchange (ETDEWEB)

    James, Christian; Seignemartin, Violaine; James, Stephen J. [Food Refrigeration and Process Engineering Research Centre (FRPERC), University of Bristol, Churchill Building, Langford, Bristol BS40 5DU (United Kingdom)

    2009-03-15

    This work shows that peeled garlic cloves demonstrate significant supercooling during freezing under standard conditions and can be stored at temperatures well below their freezing point (-2.7 C) without freezing. The nucleation point or 'metastable limit temperature' (the point at which ice crystal nucleation is initiated) of peeled garlic cloves was found to be between -7.7 and -14.6 C. Peeled garlic cloves were stored under static air conditions at temperatures between -6 and -9 C for up to 69 h without freezing, and unpeeled whole garlic bulbs and cloves were stored for 1 week at -6 C without freezing. (author)

  6. Heterogeneous freezing of water droplets containing kaolinite and montmorillonite particles

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2010-04-01

    Full Text Available Clouds composed of both ice particles and supercooled liquid water droplets exist at temperatures above ~236 K. These mixed phase clouds, which strongly impact climate, are very sensitive to the presence of solid particles that can catalyse freezing. In this paper we describe experiments to determine the rate at which kaolinite and montmorillonite nucleate ice when immersed within water droplets. These are the first immersion mode experiments in which the ice nucleating ability of individual minerals has been determined quantitatively. Water droplets containing a known amount of clay mineral were supported on a hydrophobic surface and cooled at a rate of 10 K min−1. The temperatures at which individual 10–40 μm diameter droplets froze were determined by optical microscopy. As the concentration of kaolinite in the droplets was increased from 0.005 wt% to 1 wt% the median nucleation temperature increased from close to the homogeneous nucleation limit (236 K to 240.8±0.6 K. We go onto show that the probability of freezing scales with surface area of the kaolinite inclusions rather than, as is often assumed, the volume of the droplet. When droplets contained montmorillonite ice always nucleated at 245.8±0.6 K, independent of the mineral concentration. We report temperature dependent nucleation rates and present parameterisations for nucleation by these minerals which capture the surface area and cooling rate dependence of the nucleation rate. We show that our parameterisations produce significantly different results to parameterisations employed in global models. These results also highlight the importance of understanding the ice nucleating properties of individual minerals rather than complex mixtures of minerals found in natural dusts and so-called test dusts.

  7. [Studies of viability and vitality after freezing of the probiotic yeast Saccharomyces boulardii: physiological preconditioning effect].

    Science.gov (United States)

    Pardo, Silvina; Galvagno, Miguel Angel; Cerrutti, Patricia

    2009-06-30

    The aim of this study was to evaluate the vitality and viability of the probiotic yeast Saccharomyces boulardii after freezing/thawing and the physiological preconditioning effect on these properties. The results indicate that the specific growth rate (0.3/h(-1)) and biomass (2-3 x10(8)cells/ml) of S. boulardii obtained in flasks shaken at 28 degrees C and at 37 degrees C were similar. Batch cultures of the yeast in bioreactors using glucose or sugar-cane molasses as carbon sources, reached yields of 0.28 g biomass/g sugar consumed, after 10h incubation at 28 degrees C; the same results were obtained in fed batch fermentations. On the other hand, in batch cultures, the vitality of cells recovered during the exponential growth phase was greater than the vitality of cells from the stationary phase of growth. Vitality of cells from fed-batch fermentations was similar to that of stationary growing cells from batch fermentations. Survival to freezing at -20 degrees C and subsequent thawing of cells from batch cultures was 0.31% for cells in exponential phase of growth and 11.5% for cells in stationary phase. Pre-treatment of this yeast in media with water activity (a(w)) 0.98 increased the survival to freezing of S. boulardii cells stored at -20 degrees C for 2 months by 10 fold. Exposure of the yeast to media of reduced a(w) and/or freezing/thawing process negatively affected cell vitality. It was concluded that stress conditions studied herein decrease vitality of S. boulardii. Besides, the yeast strain studied presented good tolerance to bile salts even at low pH values. PMID:19631167

  8. Ultrastructure and energy-dispersive x-ray microanalysis of cartilage after rapid freezing, low temperature freeze drying, and embedding in Spurr's resin

    Energy Technology Data Exchange (ETDEWEB)

    Appleton, J.; Lyon, R.; Swindin, K.J.; Chesters, J.

    1985-10-01

    In order to undertake meaningful high-resolution x-ray microanalysis of tissues, methods should be used that minimize the introduction of artefacts produced by loss or translocation of ions. The most ideal method is rapid freezing but the subsequent sectioning of frozen tissues is technically difficult. An alternative method is to freeze dry the tissues at a low temperature, and then embed them in resin. This facilitates the rapid production of reproducible thin sections. With freeze-dried, embedded hypertrophic cartilage, the morphology was similar to that seen using aqueous fixatives even when no additional electron density is introduced by the use of osmium vapor. Energy-dispersive analysis of specific areas show that little or no loss or migration of ions occurs from structures such as mitochondria. Mitochondrial granules consisting of calcium and phosphorus precipitates were not observed except where the cells were damaged as a result of the freezing process. This may suggest that these granules only appear when tissue is damaged because of inadequate preservation.

  9. Assessment of three generations of mice derived by ICSI using freeze-dried sperm

    Science.gov (United States)

    Li, Ming-Wen; Willis, Brandon J.; Griffey, Stephen M.; Spearow, Jimmy L.; Lloyd, K.C. Kent

    2016-01-01

    Summary Although the derivation of mice by intracytoplasmic sperm injection (ICSI) using freeze-dried sperm has been demonstrated previously, a comprehensive analysis of their viability, health, and fertility has not. The purpose of the present study was to determine the extent to which ICSI using freeze-dried sperm stored at 4 °C for 1–2 months from mice on either an inbred (C57BL/6J) or hybrid (B6D2F1/J) genetic background results in genomic instability and/or phenotypic abnormality in mice and two generations of their progeny. Fertilization rates (number of 2-cells per injected oocytes) using ICSI of fresh and freeze-dried sperm were similar within and between mouse strains, although fewer freeze-dried sperm-derived embryos than fresh sperm-derived embryos developed to blastocysts in vitro (C57BL/6J and B6D2F1/J) and liveborn pups in vivo (B6D2F1/J only). Nevertheless, once born, mice derived by ICSI using freeze-dried sperm in both mouse strains were healthy and reproductively sound. No major differences in litter size, weaning rate, and sex ratio were noted in the two generations of progeny (F2 and F3) of ICSI-derived offspring using freeze-dried sperm compared with that in the natural mating (control) group. Further, there was no evidence that either ICSI or freeze drying induced genomic instability, as determined by microsatellite analysis of the derived mice and subsequent generations when compared with both parental genotypes, nor were there differences in the number or types of pathological changes in any of the three generations of progeny. We conclude that viable, healthy and genomically stable mice can be derived by ICSI using freeze-dried mouse sperm stored in the refrigerator for at least 2 months. Further, because freeze drying is a simpler and more economical technique compared with embryo and sperm cryopreservation, the results of this study justify additional research to continue to develop and enhance the technique for the preservation

  10. Low temperature freezing followed by dispersive solid phase extraction for the determination of 104 pesticide residues in vegetable oils using ultra-performance liquid chromatography-tandem mass spectrometry%低温冷冻及分散固相萃取净化-超高效液相色谱-串联质谱法测定植物油中104种农药残留

    Institute of Scientific and Technical Information of China (English)

    徐娟; 王岚; 黄华军; 陈捷; 陈文锐; 相大鹏

    2015-01-01

    A method using liquid-liquid extraction( LLE)followed by clean-up steps of centrif-ugation,freezing and dispersive solid phase extraction( D-SPE )and ultra-performance liquid chromatography(UPLC)coupled with tandem mass spectrometry(MS/MS)has been devel-oped for the determination of trace levels of 104 pesticides in vegetable oils. LLE has been opti-mized to extract these pesticide residues from oils to obtain the highest recoveries of pesticides and the lowest co-extract fat residue in the final extract. In addition,the centrifugation and freezing steps as well as D-SPE with primary secondary amine( PSA ),graphite carbon black ( GCB)and C18 were used as the clean-up steps to minimize the co-extract fat. The recoveries obtained ranged from 55% to 121% and the relative standard deviations( RSDs)ranged from 0. 47% to 19. 2% at the spiked levels of 0. 01,0. 02 and 0. 05 mg/kg. This method,combining with accurate and sensitive detection,allowed quantification and confirmation at levels as low as 1 μg/kg for 80% of the analytes. The limits of quantification( LOQs)of the most compounds were below the maximum residue limits( MRLs)established by the Chinese legislations for oils. The proposed method was applied successfully for the residue determination of the selected pesticides in oils.%建立了适用于植物油中104种农药残留的检测方法。通过液液萃取( LLE)提取目标化合物,再借助离心、冷冻和分散固相萃取( D-SPE)净化手段,依托超高效液相色谱-串联质谱测定。以回收率和共提取物为衡量指标,着重优化了6种提取方式、不同冷冻时间及PSA( primary secondary amine)、GCB( graphite carbon black)和C18这3种不同固相萃取填料不同组合的效果。在0.01、0.02和0.05 mg/kg水平的平均添加回收率为55%~121%,RSD为0.47%~19.2%,80%的目标物的定量限可达到1μg/kg,低于我国相关标准限量,能够满足多种农药残留同时分析

  11. Ground freezing for containment of hazardous waste

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-07-01

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

  12. Cold acclimation induced accumulation of phenolic compounds and freezing tolerance in Ammopiptanthus mongolicus

    Institute of Scientific and Technical Information of China (English)

    Liu Mei-qin; Chen Yi-yin; Lu Cun-fu; Zhang Hui; Yin Wei-lun

    2007-01-01

    Ammopiptanthus mongolicus, the only freezing tolerant evergreen broad-leaved shrub, local species of the Alashan desert,northwest sand area of China, can survive -30℃ or even lower temperature in winter. In the present study, the secondary products phenolics in A. mongolicus cotyledons were determined to study the effects ofphenolics on cold tolerance. Cytochemical localization of phenolics in cotyledon cells was observed by electron microscopy and the content of phenolic compounds was assayed by spectrophotometric measurement. The results showed that the freezing tolerance of A. mongolicus seedlings increased after acclimation at 2-6℃ for 14 days, which accompanied the increase of the content of phenolic compounds in cotyledons. Cytochemical observation showed that phenolic deposits were mainly localized in vacuoles and in close proximity to tonoplast, and also in the cytoplasm. The amount and the size of phenolics droplets increased obviously in cytoplasm and vacuoles after cold acclimation, predominantly aggregated along membranes of vacuoles and tonoplast. No phenolic deposits were found in cell walls. As hydrogen- or electron-donating agents, phenolics may protect plant cells against reactive oxygen species formed during chilling or freezing stress and improve the freezing tolerance of cold-acclimated A. mongolicus seedlings.

  13. Freezing enhancement around a horizontal tube using copper foil disks

    Science.gov (United States)

    Sugawara, M.; Komatsu, Y.; Takahashi, Y.; Beer, H.

    2011-12-01

    Freezing of water saturated in circumferentially arranged copper foils around a cooling tube is studied experimentally and numerically. The copper foils need not to be welded to the cooling tube but are merely placed around the tube so that the freezing system is easily arranged. Copper foils greatly enhance freezing compared with that of a bare tube, even with a small copper volume fraction in the freezing system. Numerical calculations by means of a continuum model predict well freezing enhancement. The effect of the copper foils is also considered numerically for the melting process in order to compare with freezing. It is seen that copper foils contribute more to the melting enhancement than to the increase of the freezing rate.

  14. Scaling-Up Eutectic Freeze Crystallization

    OpenAIRE

    Genceli, F.E.

    2008-01-01

    A novel crystallization technology, Eutectic Freeze Crystallization (EFC) has been investigated and further developed in this thesis work. EFC operates around the eutectic temperature and composition of aqueous solutions and can be used for recovery of (valuable) dissolved salts (and/or or acids) and water from a wide variety of aqueous process streams. Using EFC, processes producing large quantities of saline solutions could be carried out in an ecologically and economically attractive way. ...

  15. X-ray and Electrochemical Impedance Spectroscopy Diagnostic Investigations of Liquid Water in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers

    Science.gov (United States)

    Antonacci, Patrick

    In this thesis, electrochemical impedance spectroscopy (EIS) and synchrotron x-ray radiography were utilized to characterize the impact of liquid water distributions in polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs) on fuel cell performance. These diagnostic techniques were used to quantify the effects of liquid water visualized on equivalent resistances measured through EIS. The effects of varying the thickness of the microporous layer (MPL) of GDLs were studied using these diagnostic techniques. In a first study on the feasibility of this methodology, two fuel cell cases with a 100 microm-thick and a 150 microm-thick MPL were compared under constant current density operation. In a second study with 10, 30, 50, and 100 microm-thick MPLs, the liquid water in the cathode substrate was demonstrated to affect mass transport resistance, while the liquid water content in the anode (from back diffusion) affected membrane hydration, evidenced through ohmic resistance measurements.

  16. NaCl stress impact on the key enzymes in glycolysis from Lactobacillus bulgaricus during freeze-drying.

    Science.gov (United States)

    Li, Chun; Sun, Jinwei; Qi, Xiaoxi; Liu, Libo

    2015-01-01

    The viability of Lactobacillus bulgaricus in freeze-drying is of significant commercial interest to dairy industries. In the study, L.bulgaricus demonstrated a significantly improved (p enzymes in glycolysis during 2% NaCl stress were studied. NaCl stress significantly enhanced (p enzymes (phosphofructokinase, pyruvate kinase, and lactate dehydrogenase) decreased during freeze-drying, and NaCl stress were found to improve activities of these enzymes before and after freeze-drying. However, a transcriptional analysis of the corresponding genes suggested that the effect of NaCl stress on the expression of the pfk2 gene was not obvious. The increased survival of freeze-dried cells of L. bulgaricus under NaCl stress might be due to changes in only the activity or translation level of these enzymes in different environmental conditions but have no relation to their mRNA transcription level.

  17. Saccharomyces cerevisiae glycerol/H+ symporter Stl1p is essential for cold/near-freeze and freeze stress adaptation. A simple recipe with high biotechnological potential is given

    Directory of Open Access Journals (Sweden)

    Ferreira Célia

    2010-11-01

    Full Text Available Abstract 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.

  18. Liquids and liquid mixtures

    CERN Document Server

    Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S

    2013-01-01

    Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami

  19. Atmospheric freeze drying assisted by power ultrasound

    Science.gov (United States)

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

    2012-12-01

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

  20. The influence of freezing rates on bovine pericardium tissue Freeze-drying

    Directory of Open Access Journals (Sweden)

    Camila Figueiredo Borgognoni

    2009-12-01

    Full Text Available The bovine pericardium has been used as biomaterial in developing bioprostheses. Freeze-drying is a drying process that could be used for heart valve's preservation. The maintenance of the characteristics of the biomaterial is important for a good heart valve performance. This paper describes the initial step in the development of a bovine pericardium tissue freeze-drying to be used in heart valves. Freeze-drying involves three steps: freezing, primary drying and secondary drying. The freezing step influences the ice crystal size and, consequently, the primary and secondary drying stages. The aim of this work was to investigate the influence of freezing rates on the bovine pericardium tissue freeze-drying parameters. The glass transition temperature and the structural behaviour of the lyophilized tissues were determined as also primary and secondary drying time. The slow freezing with thermal treatment presented better results than the other freeze-drying protocols.O pericárdio bovino é um material utilizado na fabricação de biopróteses. A liofilização é um método de secagem que vem sendo estudado para a conservação de válvulas cardíacas. A preservação das características do biomaterial é de fundamental importância no bom funcionamento das válvulas. Este artigo é a primeira etapa do desenvolvimento do ciclo de liofilização do pericárdio bovino. Liofilização é o processo de secagem no qual a água é removida do material congelado por sublimação e desorção da água incongelável, sob pressão reduzida. O congelamento influencia o tamanho do cristal de gelo e, consequentemente, a secagem primária e secundária. O objetivo deste estudo foi verificar a influência das taxas de congelamento nos parâmetros de liofilização do pericárdio bovino. Determinou-se a temperatura de transição vítrea e o comportamento estrutural do pericárdio bovino liofilizado. Determinou-se o tempo da secagem primária e secundária. O

  1. Food freezing with simultaneous surface dehydration: approximate prediction of weight loss during freezing and storage

    Energy Technology Data Exchange (ETDEWEB)

    Campanone, Laura A.; Salvadori, Viviana O.; Mascheroni, Rodolfo H. [Centro de Investigacion Desarollo en Criotecnologia de Alimentos (CIDCA), Facultad de Ciencias Exactas, La Plata (Argentina); MODIAL, Facultad de Ingenieria, La Plata (Argentina)

    2005-03-01

    Weight loss of unpackaged foods during freezing and later storage is an important quality and economic issue. It is originated on surface ice sublimation due to differences in water activity between food surface and the refrigerating air. Weight loss rate is determined by refrigerating conditions and product characteristics. The modelling of this phenomenon has merited very little attention; at present there are no simplified methods to predict weight losses during the freezing and the storage of unpackaged foods. In previous studies we developed a detailed model for the simultaneous heat and mass transfer during food freezing and storage with ice sublimation. Based on the information of this numerical model, simplified analytical methods for the prediction of weight loss during the freezing and the storage of unpackaged frozen foods were developed. The methods account for product characteristics and storage conditions. The prediction equations are very simple and results of their use - simulating usual freezing and storage conditions for different products - give very good accuracy when tested against the previously cited numerical model and experimental data. (Author)

  2. The Production of a Stable Infliximab Powder: The Evaluation of Spray and Freeze-Drying for Production

    Science.gov (United States)

    Kanojia, Gaurav; Have, Rimko ten; Bakker, Arjen; Wagner, Koen; Frijlink, Henderik W.; Kersten, Gideon F. A.; Amorij, Jean-Pierre

    2016-01-01

    In prospect of developing an oral dosage form of Infliximab, for treatment of Crohn’s disease and rheumatoid arthritis, freeze-drying (vial vs Lyoguard trays) and spray-drying were investigated as production method for stable powders. Dextran and inulin were used in combination with sucrose as stabilizing excipients. The drying processes did not affect Infliximab in these formulations, i.e. both the physical integrity and biological activity (TNF binding) were retained. Accelerated stability studies (1 month at 60°C) showed that the TNF binding ability of Infliximab was conserved in the freeze-dried formulations, whereas the liquid counterpart lost all TNF binding. After thermal treatment, the dried formulations showed some chemical modification of the IgG in the dextran-sucrose formulation, probably due to Maillard reaction products. This study indicates that, with the appropriate formulation, both spray-drying and freeze-drying may be useful for (bulk) powder production of Infliximab. PMID:27706175

  3. A sample-freezing drive shoe for a wire line piston core sampler

    Science.gov (United States)

    Murphy, F.; Herkelrath, W.N.

    1996-01-01

    Loss of fluids and samples during retrieval of cores of saturated, noncohesive sediments results in incorrect measures of fluid distributions and an inaccurate measure of the stratigraphic position of the sample. To reduce these errors, we developed a hollow drive shoe that freezes in place the lowest 3 inches (75 mm) of a 1.88-inch-diameter (48 mm), 5-foot-long (1.5 m) sediment sample taken using a commercial wire line piston core sampler. The end of the core is frozen by piping liquid carbon dioxide at ambient temperature through a steel tube from a bottle at the land surface to the drive shoe where it evaporates and expands, cooling the interior surface of the shoe to about -109??F (-78??C). Freezing a core end takes about 10 minutes. The device was used to collect samples for a study of oil-water-air distributions, and for studies of water chemistry and microbial activity in unconsolidated sediments at the site of an oil spill near Bemidji, Minnesota. Before freezing was employed, samples of sandy sediments from near the water table sometimes flowed out of the core barrel as the sampler was withdrawn. Freezing the bottom of the core allowed for the retention of all material that entered the core barrel and lessened the redistribution of fluids within the core. The device is useful in the unsaturated and shallow saturated zones, but does not freeze cores well at depths greater than about 20 feet (6 m) below water, possibly because the feed tube plugs with dry ice with increased exhaust back-pressure, or because sediment enters the annulus between the core barrel and the core barrel liner and blocks the exhaust.

  4. Efficient generation of multipotent mesenchymal stem cells from umbilical cord blood in stroma-free liquid culture.

    Directory of Open Access Journals (Sweden)

    Rowayda Peters

    Full Text Available BACKGROUND: Haematopoiesis is sustained by haematopoietic (HSC and mesenchymal stem cells (MSC. HSC are the precursors for blood cells, whereas marrow, stroma, bone, cartilage, muscle and connective tissues derive from MSC. The generation of MSC from umbilical cord blood (UCB is possible, but with low and unpredictable success. Here we describe a novel, robust stroma-free dual cell culture system for long-term expansion of primitive UCB-derived MSC. METHODS AND FINDINGS: UCB-derived mononuclear cells (MNC or selected CD34(+ cells were grown in liquid culture in the presence of serum and cytokines. Out of 32 different culture conditions that have been tested for the efficient expansion of HSC, we identified one condition (DMEM, pooled human AB serum, Flt-3 ligand, SCF, MGDF and IL-6; further denoted as D7 which, besides supporting HSC expansion, successfully enabled long-term expansion of stromal/MSC from 8 out of 8 UCB units (5 MNC-derived and 3 CD34(+ selected cells. Expanded MSC displayed a fibroblast-like morphology, expressed several stromal/MSC-related antigens (CD105, CD73, CD29, CD44, CD133 and Nestin but were negative for haematopoietic cell markers (CD45, CD34 and CD14. MSC stemness phenotype and their differentiation capacity in vitro before and after high dilution were preserved throughout long-term culture. Even at passage 24 cells remained Nestin(+, CD133(+ and >95% were positive for CD105, CD73, CD29 and CD44 with the capacity to differentiate into mesodermal lineages. Similarly we show that UCB derived MSC express pluripotency stem cell markers despite differences in cell confluency and culture passages. Further, we generated MSC from peripheral blood (PB MNC of 8 healthy volunteers. In all cases, the resulting MSC expressed MSC-related antigens and showed the capacity to form CFU-F colonies. CONCLUSIONS: This novel stroma-free liquid culture overcomes the existing limitation in obtaining MSC from UCB and PB enabling so far unmet

  5. Improved power conversion efficiency of dye-sensitized solar cells using side chain liquid crystal polymer embedded in polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Woosum [Department of Chemistry Education, and Department of Frontier Materials Chemistry, and Institute for Plastic Information and Energy Materials, Pusan National University, Busan 609-735 (Korea, Republic of); Lee, Jae Wook, E-mail: jlee@donga.ac.kr [Department of Chemistry, Dong-A University, Busan 604-714 (Korea, Republic of); Gal, Yeong-Soon [Polymer Chemistry Lab, College of General Education, Kyungil University, Hayang 712-701 (Korea, Republic of); Kim, Mi-Ra, E-mail: mrkim2@pusan.ac.kr [Department of Polymer Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Jin, Sung Ho, E-mail: shjin@pusan.ac.kr [Department of Chemistry Education, and Department of Frontier Materials Chemistry, and Institute for Plastic Information and Energy Materials, Pusan National University, Busan 609-735 (Korea, Republic of)

    2014-02-14

    Side chain liquid crystal polymer (SCLCP) embedded in poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-co-HFP)-based polymer electrolytes (PVdF-co-HFP:side chain liquid crystal polymer (SCLCP)) was prepared for dye-sensitized solar cell (DSSC) application. The polymer electrolytes contained tetrabutylammonium iodide (TBAI), iodine (I{sub 2}), and 8 wt% PVdF-co-HFP in acetonitrile. DSSCs comprised of PVdF-co-HFP:SCLCP-based polymer electrolytes displayed enhanced redox couple reduction and reduced charge recombination in comparison to those of the conventional PVdF-co-HFP-based polymer electrolyte. The significantly increased short-circuit current density (J{sub sc}, 10.75 mA cm{sup −2}) of the DSSCs with PVdF-co-HFP:SCLCP-based polymer electrolytes afforded a high power conversion efficiency (PCE) of 5.32% and a fill factor (FF) of 0.64 under standard light intensity of 100 mW cm{sup −2} irradiation of AM 1.5 sunlight. - Highlights: • We developed the liquid crystal polymer embedded on polymer electrolyte for DSSCs. • We fabricated the highly efficient DSSCs using polymer electrolyte. • The best PCE achieved for P1 is 5.32% using polymer electrolyte.

  6. Nanocomposite semi-solid redox ionic liquid electrolytes with enhanced charge-transport capabilities for dye-sensitized solar cells.

    Science.gov (United States)

    Rutkowska, Iwona A; Marszalek, Magdalena; Orlowska, Justyna; Ozimek, Weronika; Zakeeruddin, Shaik M; Kulesza, Pawel J; Grätzel, Michael

    2015-08-10

    The ability of Pt nanostructures to induce the splitting of the II bond in iodine (triiodide) molecules is explored here to enhance electron transfer in the iodine/iodide redox couple. Following the dispersal of Pt nanoparticles at 2 % (weight) level, charge transport was accelerated in triiodide/iodide-containing 1,3-dialkylimidazolium room-temperature ionic liquid. If both Pt nanoparticles and multi-walled carbon nanotubes were introduced into the ionic-liquid-based system, a solid-type (nonfluid) electrolyte was obtained. By using solid-state voltammetric (both sandwich-type and microelectrode-based) methodology, the apparent diffusion coefficients for charge transport increased to approximately 1×10(-6)  cm(2)  s(-1) upon the incorporation of the carbon-nanotube-supported iodine-modified Pt nanostructures. A dye-sensitized solar cell comprising TiO2 covered with a heteroleptic Ru(II) -type sensitizer (dye) and the semisolid triiodide/iodide ionic liquid electrolyte admixed with carbon-nanotube-supported Pt nanostructures yielded somewhat higher power conversion efficiencies (up to 7.9 % under standard reporting conditions) than those of the analogous Pt-free system. PMID:26119519

  7. Investigations on the cell metabolomics basis of multidrug resistance from tumor cells by ultra-performance liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Zhang, Ruixing; Zhuang, Xiaoyu; Zong, Li; Liu, Shu; Liu, Zhiqiang; Song, Fengrui

    2016-08-01

    Although anticancer drug resistance has been linked to high expression of P-glycoprotein and the enhanced DNA repair ability, the biochemical process and the underlying mechanisms of drug resistance are not clear. In order to clarify the biochemical mechanisms of drug resistance during anticancer drug treatment, we studied the metabolomics of MCF-7/S and MCF-7/Adr cell lines, the COC1 and COC1/DDP cell lines, including the metabolic pathways of multidrug-resistant tumor cells and the changes of endogenous substances in cells. The intracellular metabolites were profiled using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). In this study, 24 biomarkers in MCF-7/Adr cells and 15 biomarkers in COC1/DDP cells that are involved in some important metabolic pathways were putatively identified. Several metabolic pathways are changed in tumor cells showing drug resistance, such as protein synthesis pathways, cysteine synthesis, the glutamine metabolic pathway, and the ammonia cycle; the first of these are involved in the synthesis of some important proteins including membrane proteins, multidrug resistance-associated proteins, and P-glycoprotein (P-gp). Proteins related to drug resistance were overexpressed in multidrug-resistant tumor cells. These proteins depended on energy and play important roles in the emergence of drug resistance. The changes in glutathione and cysteine metabolic pathways showed that the cells can activate related metabolic pathways and reduce the cell apoptosis when they encounter oxidative damage. These findings indicate that drug resistance is likely associated with increased P-gp synthesis and reduced apoptosis of tumor cells. Graphical Abstract Drug resistance was charactered in the changing of genomics and proteomics. Like enhancing DNA repair, reducing uptake, high P-g protein expression. Here, we studied the changes of metabolite pathway which could be also play an imported role in drug resistance. PMID

  8. Leavening ability and freeze tolerance of yeasts isolated from traditional corn and rye bread doughs.

    Science.gov (United States)

    Almeida, M J; Pais, C

    1996-12-01

    Strains of Saccharomyces cerevisiae and Torulaspora delbrueckii isolated from traditional bread doughs displayed dough-raising capacities similar to the ones found in baker's yeasts. During storage of frozen doughs, strains of T. delbrueckii (IGC 5321, IGC 5323, and IGC 4478) presented approximately the same leavening ability for 30 days. Cell viability was not significantly affected by freezing, but when the dough was submitted to a bulk fermentation before being stored at -20 degrees C, there was a decrease in the survival ratio which depended on the yeast strain. Furthermore, the leavening ability after 4 days of storage decreased as the prefermentation period of the dough before freezing increased, except for strains IGC 5321 and IGC 5323. These two strains retained their fermentative activity after 15 days of storage and 2.5 h of prefermentation, despite showing a reduction of viable cells under the same conditions. The intracellular trehalose content was higher than 20% (wt/wt) in four of the yeasts tested: the two commercial strains of baker's yeast (S. cerevisiae IGC 5325 and IGC 5326) and the two mentioned strains of T. delbrueckii (IGC 5321 and IGC 5323). However, the strains of S. cerevisiae were clearly more susceptible to freezing damages, indicating that other factors may contribute to the freeze tolerance of these yeasts. PMID:8953712

  9. Continuous On-Chip Cell Separation Based on Conductivity-Induced Dielectrophoresis with 3D Self-Assembled Ionic Liquid Electrodes.

    Science.gov (United States)

    Sun, Mingrui; Agarwal, Pranay; Zhao, Shuting; Zhao, Yi; Lu, Xiongbin; He, Xiaoming

    2016-08-16

    Dielectrophoresis (DEP) has been widely explored to separate cells for various applications. However, existing DEP devices are limited by the high cost associated with the use of noble metal electrodes, the need of high-voltage electric field, and/or discontinuous separation (particularly for devices without metal electrodes). We developed a DEP device with liquid electrodes, which can be used to continuously separate different types of cells or particles based on positive DEP. The device is made of polydimethylsiloxane (PDMS), and ionic liquid is used to form the liquid electrodes, which has the advantages of low cost and easy fabrication. Moreover, the conductivity gradient is utilized to achieve the DEP-based on-chip cell separation. The device was used to separate polystyrene microbeads and PC-3 human prostate cancer cells with 94.7 and 1.2% of the cells and microbeads being deflected, respectively. This device is also capable of separating live and dead PC-3 cancer cells with 89.8 and 13.2% of the live and dead cells being deflected, respectively. Moreover, MDA-MB-231 human breast cancer cells could be separated from human adipose-derived stem cells (ADSCs) using this device with high purity (81.8 and 82.5% for the ADSCs and MDA-MB-231 cells, respectively). Our data suggest the great potential of cell separation based on conductivity-induced DEP using affordable microfluidic devices with easy operation.

  10. The nature of single-ion activity coefficients calculated from potentiometric measurements on cells with liquid junctions

    Energy Technology Data Exchange (ETDEWEB)

    Zarubin, Dmitri P., E-mail: dmitri.zarubin@mtu-net.ru [Department of Physical and Collod Chemistry, Moscow State University of Technology and Management, 73 Zemlyanoi Val, Moscow 109803 (Russian Federation)

    2011-08-15

    Highlights: > Problem of ionic activity coefficients, determined by potentiometry, is reconsidered. > They are found to be functions of mean activity coefficients and transport numbers of ions. > The finding is verified by calculations and comparing the results with reported data. > Calculations are performed for systems with single electrolytes and binary mixtures. - Abstract: Potentiometric measurements on cells with liquid junctions are sometimes used for calculations of single-ion activity coefficients in electrolyte solutions, the incidence of this being increased recently. As surmised by Guggenheim in the 1930s, such coefficients (of ions i), {gamma}{sub i}, are actually complicated functions of mean ionic activity coefficients, {gamma}{sub {+-}}, and transport numbers of ions, t{sub i}. In the present paper specific functions {gamma}{sub i}({gamma}{sub {+-}}, t{sub i}) are derived for a number of cell types with an arbitrary mixture of strong electrolytes in a one-component solvent in the liquid-junction system. The cell types include cells with (i) identical electrodes, (ii) dissimilar electrodes reversible to the same ions, (iii) dissimilar electrodes reversible to ions of opposite charge signs, (iv) dissimilar electrodes reversible to different ions of the same charge sign, and (v) identical reference electrodes and an ion-selective membrane permeable to ions of only one type. Pairs of functions for oppositely charged ions are found to be consistent with the mean ionic activity coefficients as would be expected for pairs of the proper {gamma}{sub i} quantities by definition of {gamma}{sub {+-}}. The functions are tested numerically on some of the reported {gamma}{sub i} datasets that are the more tractable. A generally good agreement is found with data reported for cells with single electrolytes HCl and KCl in solutions, and with binary mixtures in the liquid-junction systems of KCl from the reference solutions and NaCl and HCl from the test solutions. It

  11. Solidification of liquid electrolyte with imidazole polymers for quasi-solid-state dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Quasi-solid-state electrolytes were prepared by employing the imidazole polymers to solidify the liquid electrolyte containing lithium iodide, iodine and ethylene carbonate (EC)/propylene carbonate (PC) mixed solvent. The ionic conductivity and diffusion behavior of triiodide in the quasi-solid-state electrolytes were examined in terms of the polymer content. Application of the quasi-solid-state electrolytes to the dye-sensitized solar cells, the maximum energy conversion efficiency of 7.6% (AM 1.5, 100 mW cm-2) was achieved. The dependence of the photovoltaic performance on the polymer content and on the different anions of the imidazole polymers was studied by electrochemical impedance spectroscopy and cyclic voltammetry. The results indicate the charge transfer behaviors occurred at nanocrystalline TiO2/electrolyte and Pt/electrolyte interface play an important role in influencing the photovoltaic performance of quasi-solid-state dye-sensitized solar cells

  12. Solidification of liquid electrolyte with imidazole polymers for quasi-solid-state dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang Miao [Beijing National laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Lin Yuan [Beijing National laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)], E-mail: linyuan@iccas.ac.cn; Zhou Xiaowen; Xiao Xurui [Beijing National laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Yang Lei [Beijing National laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Feng Shujing; Li Xueping [Beijing National laboratory for Molecular Sciences, Key laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

    2008-01-15

    Quasi-solid-state electrolytes were prepared by employing the imidazole polymers to solidify the liquid electrolyte containing lithium iodide, iodine and ethylene carbonate (EC)/propylene carbonate (PC) mixed solvent. The ionic conductivity and diffusion behavior of triiodide in the quasi-solid-state electrolytes were examined in terms of the polymer content. Application of the quasi-solid-state electrolytes to the dye-sensitized solar cells, the maximum energy conversion efficiency of 7.6% (AM 1.5, 100 mW cm{sup -2}) was achieved. The dependence of the photovoltaic performance on the polymer content and on the different anions of the imidazole polymers was studied by electrochemical impedance spectroscopy and cyclic voltammetry. The results indicate the charge transfer behaviors occurred at nanocrystalline TiO{sub 2}/electrolyte and Pt/electrolyte interface play an important role in influencing the photovoltaic performance of quasi-solid-state dye-sensitized solar cells.

  13. Specific features of attenuated light transmission by liquid-crystal twist cells in constant and alternating electric fields

    Science.gov (United States)

    Konshina, E. A.; Amosova, L. P.

    2012-07-01

    Optical transmission characteristics of dual-frequency nematic liquid crystal (NLC) twist cells with different alignment layers (rubbed polyimide and obliquely deposited cerium dioxide) have been studied in constant and alternating electric fields. It has been established that a change in the optical (twist effect) threshold and dynamic range of attenuated transmission depend both on the boundary conditions (that influence the screening of applied voltage) and on the parameters of the applied electric field. The maximum dynamic range (49.5 dB) has been obtained in the cell with a CeO2 alignment layer controlled by a constant potential. In the case of an alternating electric field, the dynamic range decreases because of reduced effective voltage.

  14. On the stability of homogenous orientation in a plane-parallel cell of a liquid crystal doped with nanoparticles

    International Nuclear Information System (INIS)

    The problems of molecules homogenous orientations stability of nematic liquid crystal (NLC) doped with small amount of cholesteric LC are considered. The LC cell with homeotropic orientation on the wall and the cell with a twist-oriented molecules on the boundaries are studied. The problems are solved using the Noether theorem for LC. The invariance of the form of free energy to translation according to the Noether theorem leads to conservation of the momentum flux, and invariance with respect to the rotation group leads to conservation of the angular momentum flux. These conservation laws are used to get thresholds of molecules homogenous orientation stability of mentioned mixture and the influence of nanoparticles on this thresholds

  15. Effects of different quick freezing processes on the quality characteristics of litopenaeus vannamei%冷冻方式对凡纳滨对虾品质特性的影响

    Institute of Scientific and Technical Information of China (English)

    杨利艳; 曹文红; 章超桦; 吉宏武

    2011-01-01

    以质构、盐溶性蛋白、ATPase活性、巯基含量、失水率及pH为指标,研究液氮速冻、-75℃超低温速冻和-18℃冷库冷冻3种冷冻方式对凡纳滨对虾品质特性的影响.结果表明:液氮速冻处理组失水率最低,盐溶性蛋白含量、巯基含量、ATPase活性及pH值均显著低于新鲜对虾,却明显高于-75℃超低温速冻和-18℃冷库冷冻;凡纳滨对虾经3种冷冻方式处理后其质构变化不大,其中液氮速冻处理组与新鲜对虾之间的差异最小.%Taking fluid loss, textural, pH, salt soluble protein, AT-Pase activity, and sulfydryl content as the indexes, the effects were studied of three different freezing processes, such as liquid nitrogen quick-freezing, - 75 ℃ ultra-low temperature quick-freezing and - 18 ℃ refrigerator freezing, on characteristics of littipenaeus vannamei muscles. The results indicated that the group which was treated by liquid nitrogen quick freezing has the least fluid loss. Although the group treated by liquid nitrogen quick-freezing had significant difference with the fresh group in pH, salt soluble protein, AT-Pase activity and sulphur content, it is better than the other freezing groups. The texture of titopentirus vannamei via the three different quick freezing processes had no significant difference between each other. The liquid nitrogen quick-freezing group has small difference with the fresh shrimp.

  16. Improved efficiency and stability of flexible dye sensitized solar cells on ITO/PEN substrates using an ionic liquid electrolyte.

    Science.gov (United States)

    Han, Yu; Pringle, Jennifer M; Cheng, Yi-Bing

    2015-01-01

    Flexible dye-sensitized solar cells (DSSCs) built on plastic substrates have attracted great interest as they are lightweight and can be roll-to-roll printed to accelerate production and reduce cost. However, plastic substrates such as PEN and PET are permeable to water, oxygen and volatile electrolyte solvents, which is detrimental to the cell stability. Therefore, to address this problem, in this work, an ionic liquid (IL) electrolyte is used to replace the volatile solvent electrolyte. The initial IL-based devices only achieved around 50% of the photovoltaic conversion efficiency of the cells using the solvent electrolyte. Current-voltage and electrochemical impedance spectroscopy (EIS) analysis of the cells in the dark indicated that this lower efficiency mainly originated from (i) a lack of blocking layer to reduce recombination, and (ii) a lower charge collection efficiency. To combat these problems, cells were developed using a 12 nm thick blocking layer, produced by atomic layer deposition, and 1 μm thick P25 TiO2 film sensitized with the hydrophobic MK-2 dye. These flexible DSSCs utilizing an IL electrolyte exhibit significantly improved efficiencies and a <10% drop in performance after 1000 h aging at 60°C under continuous light illumination. PMID:25476521

  17. On the addition of conducting ceramic nanoparticles in solvent-free ionic liquid electrolyte for dye-sensitized solar cells

    KAUST Repository

    Lee, Chuan-Pei

    2009-08-01

    Titanium carbide (TiC) is an extremely hard conducting ceramic material often used as a coating for titanium alloys as well as steel and aluminum components to improve their surface properties. In this study, conducting ceramic nanoparticles (CCNPs) have been used, for the first time, in dye-sensitized solar cells (DSSCs), and the incorporation of TiC nanoparticles in a binary ionic liquid electrolyte on the cell performance has been investigated. Cell conversion efficiency with 0.6 wt% TiC reached 1.68%, which was higher than that without adding TiC (1.18%); however, cell efficiency decreased when the TiC content reached 1.0 wt%. The electrochemical impedance spectroscopy (EIS) technique was employed to analyze the interfacial resistance in DSSCs, and it was found that the resistance of the charge-transfer process at the Pt counter electrode (Rct1) decreased when up to 1.0 wt% TiC was added. Presumably, this was due to the formation of the extended electron transfer surface (EETS) which facilitates electron transfer to the bulk electrolyte, resulting in a decrease of the dark current, whereby the open-circuit potential (VOC) could be improved. Furthermore, a significant increase in the fill factor (FF) for all TiC additions was related to the decrease in the series resistance (RS) of the DSSCs. However, at 1.0 wt% TiC, the largest charge-transfer resistance at the TiO2/dye/electrolyte interface was observed and resulted from the poor penetration of the electrolyte into the porous TiO2. The long-term stability of DSSCs with a binary ionic liquid electrolyte, which is superior to that of an organic solvent-based electrolyte, was also studied. © 2009 Elsevier B.V. All rights reserved.

  18. Survival and Growth of Epidemically Successful and Nonsuccessful Salmonella enterica Clones after Freezing and Dehydration

    DEFF Research Database (Denmark)

    Müller, Karoline; Aabo, Søren; Birk, Tina;

    2012-01-01

    contribute. During epidemiological studies, a mathematical model was developed that allowed estimation of a factor (q) accounting for the relative ability of Salmonella serovars with different antimicrobial resistances to survive in the food chain and cause human disease. Based on this q-factor, 26...... Salmonella isolates were characterized as successful or nonsuccessful. We studied the survival and growth of stationary- and exponential-phase cells of these isolates after freezing for up to 336 days in minced meat. We also investigated survival and growth after dehydration at 10°C and 82% relative humidity...... (RH) and 25°C and 49% RH for 112 days. Stationary-phase cells were reduced by less than 1 log unit during 1 year of freezing, and growth was initiated with an average lag phase of 1.7 h. Survival was lower in exponentialphase cells, but lag phases tended to be shorter. High humidity and low...

  19. Stability evaluation of freeze-dried Lactobacillus paracasei subsp. tolerance and Lactobacillus delbrueckii subsp. bulgaricus in oral capsules.

    Science.gov (United States)

    Jalali, M; Abedi, D; Varshosaz, J; Najjarzadeh, M; Mirlohi, M; Tavakoli, N

    2012-01-01

    Freeze-drying is a common preservation technology in the pharmaceutical industry. Various studies have investigated the effect of different cryoprotectants on probiotics during freeze-drying. However, information on the effect of cryoprotectants on the stability of some Lactobacillus strains during freeze-drying seems scarce. Therefore, the aim of the present study was to establish production methods for preparation of oral capsule probiotics containing Lactobacillus paracasei subsp. tolerance and Lactobacillus delbrueckii subsp. Bulgaricus. It was also of interest to examine the effect of various formulations of cryoprotectant media containing skim milk, trehalose and sodium ascorbate on the survival rate of probiotic bacteria during freeze-drying at various storage temperatures. Without any cryoprotectant, few numbers of microorganisms survived. However, microorganisms tested maintained higher viability after freeze-drying in media containing at least one of the cryoprotectants. Use of skim milk in water resulted in an increased viability after lyophilization. Media with a combination of trehalose and skim milk maintained a higher percentage of live microorganisms, up to 82%. In general, bacteria retained a higher number of viable cells in capsules containing freeze-dried bacteria with sodium ascorbate after three months of storage. After this period, a marked decline was observed in all samples stored at 23°C compared to those stored at 4°C. The maximum survival rate (about 72-76%) was observed with media containing 6% skim milk, 8% trehalose and 4% sodium ascorbate.

  20. Improving freeze-tolerance of baker's yeast through seamless gene deletion of NTH1 and PUT1.

    Science.gov (United States)

    Dong, Jian; Chen, Didi; Wang, Guanglu; Zhang, Cuiying; Du, Liping; Liu, Shanshan; Zhao, Yu; Xiao, Dongguang

    2016-06-01

    Baker's yeast strains with freeze-tolerance are highly desirable to maintain high leavening ability after freezing. Enhanced intracellular concentration of trehalose and proline in yeast is linked with freeze-tolerance. In this study, we constructed baker's yeast with enhanced freeze-tolerance by simultaneous deletion of the neutral trehalase-encoded gene NTH1 and the proline oxidase-encoded gene PUT1. We first used the two-step integration-based seamless gene deletion method to separately delete NTH1 and PUT1 in haploid yeast. Subsequently, through two rounds of hybridization and sporulation-based allelic exchange and colony PCR-mediated tetrad analysis, we obtained strains with restored URA3 and deletion of NTH1 and/or PUT1. The resulting strain showed higher cell survival and dough-leavening ability after freezing compared to the wild-type strain due to enhanced accumulation of trehalose and/or proline. Moreover, mutant with simultaneous deletion of NTH1 and PUT1 exhibits the highest relative dough-leavening ability after freezing compared to mutants with single-gene deletion perhaps due to elevated levels of both trehalose and proline. These results verified that it is applicable to construct frozen dough baker's yeast using the method proposed in this paper. PMID:26965428

  1. Liquid-Gas Phase Transition in Nuclear Equation of State

    CERN Document Server

    Lee, S J

    1997-01-01

    A canonical ensemble model is used to describe a caloric curve of nuclear liquid-gas phase transition. Allowing a discontinuity in the freeze out density from one spinodal density to another for a given initial temperature, the nuclear liquid-gas phase transition can be described as first order. Averaging over various freeze out densities of all the possible initial temperatures for a given total reaction energy, the first order characteristics of liquid-gas phase transition is smeared out to a smooth transition. Two experiments, one at low beam energy and one at high beam energy show different caloric behaviors and are discussed.

  2. Lipophilic components of the brown seaweed, Ascophyllum nodosum, enhance freezing tolerance in Arabidopsis thaliana.

    Science.gov (United States)

    Rayirath, Prasanth; Benkel, Bernhard; Mark Hodges, D; Allan-Wojtas, Paula; Mackinnon, Shawna; Critchley, Alan T; Prithiviraj, Balakrishnan

    2009-06-01

    Extracts of the brown seaweed Ascophyllum nodosum enhance plant tolerance against environmental stresses such as drought, salinity, and frost. However, the molecular mechanisms underlying this improved stress tolerance and the nature of the bioactive compounds present in the seaweed extracts that elicits stress tolerance remain largely unknown. We investigated the effect of A. nodosum extracts and its organic sub-fractions on freezing tolerance of Arabidopsis thaliana. Ascophyllum nodosum extracts and its lipophilic fraction significantly increased tolerance to freezing temperatures in in vitro and in vivo assays. Untreated plants exhibited severe chlorosis, tissue damage, and failed to recover from freezing treatments while the extract-treated plants recovered from freezing temperature of -7.5 degrees C in in vitro and -5.5 degrees C in in vivo assays. Electrolyte leakage measurements revealed that the LT(50) value was lowered by 3 degrees C while cell viability staining demonstrated a 30-40% reduction in area of damaged tissue in extract treated plants as compared to water controls. Moreover, histological observations of leaf sections revealed that extracts have a significant effect on maintaining membrane integrity during freezing stress. Treated plants exhibited 70% less chlorophyll damage during freezing recovery as compared to the controls, and this correlated with reduced expression of the chlorphyllase genes AtCHL1 and AtCHL2. Further, the A. nodosum extract treatment modulated the expression of the cold response genes, COR15A, RD29A, and CBF3, resulting in enhanced tolerance to freezing temperatures. More than 2.6-fold increase in expression of RD29A, 1.8-fold increase of CBF3 and two-fold increase in the transcript level of COR15A was observed in plants treated with lipophilic fraction of A. nodosum at -2 degrees C. Taken together, the results suggest that chemical components in A. nodosum extracts protect membrane integrity and affect the expression of

  3. Dynamical freeze-out in event-by-event hydrodynamics

    CERN Document Server

    Holopainen, Hannu

    2012-01-01

    In hydrodynamical modeling of the ultrarelativistic heavy-ion collisions the freeze-out is typically performed at a constant temperature or density. In this work we apply a dynamical freeze-out criterion, which compares the hydrodynamical expansion rate with the pion scattering rate. Recently many calculations have been done using event-by-event hydrodynamics where the initial density profile fluctuates from event to event. In these event-by-event calculations the expansion rate fluctuates strongly as well, and thus it is interesting to check how the dynamical freeze-out changes hadron distributions with respect to the constant temperature freeze-out. We present hadron spectra and elliptic flow calculated using (2+1)-dimensional ideal hydrodynamics, and show the differences between constant temperature and dynamical freeze-out criteria. We find that the differences caused by different freeze-out criteria are small in all studied cases.

  4. Theoretical approaches to the glass transition in simple liquids

    Indian Academy of Sciences (India)

    Chandan Dasgupta

    2005-05-01

    Theoretical approaches to the development of an understanding of the behaviour of simple supercooled liquids near the structural glass transition are reviewed and our work on this problem, based on the density functional theory of freezing and replicated liquid state theory, are summarized in this context. A few directions for further work on this problem are suggested.

  5. Well-plate freeze-drying

    DEFF Research Database (Denmark)

    Trnka, Hjalte; Rantanen, Jukka; Grohganz, Holger

    2015-01-01

    , cake collapse and reconstitution time. Results: Samples freeze-dried in well-plates had an acceptable visual cake appearance. Solid form analysis by high throughput X-ray powder diffraction indicated comparable polymorphic outcome independent of the container. The expected increase in moisture level...... due to increasing amount of amorphous matter in the samples was observed in both vials and well plates. Cake collapse was found to be representative in well plates and could be effectively quantified using image analysis. Reconstitution time was also found to be equal in all three platforms. Finally...

  6. High Performance Liquid Chromatography-mass Spectrometry Analysis of High Antioxidant Australian Fruits with Antiproliferative Activity Against Cancer Cells

    Science.gov (United States)

    Sirdaarta, Joseph; Maen, Anton; Rayan, Paran; Matthews, Ben; Cock, Ian Edwin

    2016-01-01

    g/mL). All other extracts were nontoxic. A total of 145 unique mass signals were detected in the lemon aspen methanolic and aqueous extracts by nonbiased high-performance liquid chromatography-mass spectrometry analysis. Of these, 20 compounds were identified as being of particular interest due to their reported antioxidant and/or anticancer activities. Conclusions: The lack of toxicity and antiproliferative activity of the high antioxidant plant extracts against HeLa and CaCo2 cancer cell lines indicates their potential in the treatment and prevention of some cancers. SUMMARY Australian fruit extracts with high antioxidant contents were potent inhibitors of CaCo2 and HeLa carcinoma cell proliferationMethanolic lemon aspen extract was particularly potent, with IC50 values of 480 μg/mL (HeLa) and 769 μg/mL (CaCo2)High-performance liquid chromatography-mass spectrometry-quadrupole time-of-flight analysis highlighted and putatively identified 20 compounds in the antiproliferative lemon aspen extractsIn contrast, lower antioxidant content extracts stimulated carcinoma cell proliferationAll extracts with antiproliferative activity were nontoxic in the Artemia nauplii assay. Abbreviations used: DPPH: di (phenyl)- (2,4,6-trinitrophenyl) iminoazanium, HPLC: High-performance liquid chromatography, IC50: The concentration required to inhibit by 50%, LC50: The concentration required to achieve 50% mortality, MS: Mass spectrometry. PMID:27279705

  7. Design review of a liquid solar collector

    Science.gov (United States)

    Wiesewmaier, B. L.

    1979-01-01

    Report documents procedures, results, and recommendations for in-depth analysis of problems with liquid-filled version of concentric-tube solar collector. Problems are related to loss of vacuum and/or violent fracture of collector elements, fluid leakage, freezing, flow anomalies, manifold damage, and other component failures.

  8. PREPARATION OF POROUS NANOCOMPOSITE SCAFFOLDS WITH HONEYCOMB MONOLITH STRUCTURE BY ONE PHASE SOLUTION FREEZE DRYING METHOD

    Institute of Scientific and Technical Information of China (English)

    Yang Xu; Duo Zhang; Zong-liang Wang; Zhan-tuan Gao; Pei-biao Zhang; Xue-si Chen

    2011-01-01

    Biodegradable porous nanocomposite scaffolds of poly(lactide-co-glycolide) (PLGA) and L-lactic acid (LAc) oligomer surface-grafted hydroxyapatite nanoparticles (op-HA) with a honeycomb monolith structure were fabricated with the single-phase solution freeze-drying method. The effects of different freezing temperatures on the properties of the scaffolds, such as microstructures, compressive strength, cell penetration and cell proliferation were studied. The highly porous and well interconnected scaffolds with a tunable pore structure were obtained. The effect of different freezing temperature (4℃, -20℃, -80℃ and -196℃) was investigated in relation to the scaffold morphology, the porosity varied from 91.2% to 83.0% and the average pore diameter varied from (167.2 ± 62.6) pm to (11.9 ± 4.2) μm while the σ10 increased significantly. The cell proliferation were decreased and associated with the above-mentioned properties. Uniform distribution of op-HA particles and homogeneous roughness of pore wall surfaces were found in the 4℃ frozen scaffold. The 4℃ frozen scaffold exhibited better cell penetration and increased cell proliferation because of its larger pore size, higher porosity and interconnection. The microstmctures described here provide a new approach for the design and fabrication of op-HA/PLGA based scaffold materials with potentially broad applicability for replacement of bone defects.

  9. Freeze-Thaw Durability of Air-Entrained Concrete

    OpenAIRE

    Huai-Shuai Shang; Ting-Hua Yi

    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. T...

  10. FEM Simulation on Artificial Freezing of Seepage Ground

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xiao-min

    2005-01-01

    The coupling mechanism in freezing process of seepage ground was studied and a simplified coupling math model was proposed. The nonlinear and coupling problems of PDEs were well solved using the exponential function, error function and normal distribution function, and a series of FEM equations of coupled fields of temperature and seepage were deduced and put forward. With the example of shaft ground freezing, the formation of freezing wall in seepage ground was simulated.

  11. SOME STUDIES ABOUT CEREALS BEHAVIOR DURING FREEZE DRYING PROCESS

    OpenAIRE

    GABRIELA-VICTORIA MNERIE; D. MNERIE; D. ŢUCU

    2013-01-01

    The paper presents some special method and equipment and the principal advantages of freeze-dried food. The freeze drying is a good method of freeze-drying for make some experiments with many kind of cereals, for the improvement that in food production. It is necessary and is possible to study the corn oil extract, wheat flour, the maltodextrin from corn, modified cornstarch, spice extracts, soy sauce, hydrolyzed wheat gluten, partially hydrogenated soybean and cottonseed oil etc. That is ver...

  12. Identifying freezing of gait in Parkinson's disease during freezing provoking tasks using waist-mounted accelerometry

    NARCIS (Netherlands)

    Zach, H.; Janssen, A.M.; Snijders, A.H.; Delval, A.; Ferraye, M.U.; Auff, E.; Weerdesteyn, V.G.; Bloem, B.R.; Nonnekes, J.H.

    2015-01-01

    BACKGROUND: Freezing of gait (FOG) is a common and debilitating phenomenon in Parkinson's disease (PD). Wearable accelerometers might help to assess FOG in the research setting. Here, we evaluate whether accelerometry can detect FOG while executing rapid full turns and while walking with rapid short

  13. Experimental quantification of contact freezing in an electrodynamic balance

    Directory of Open Access Journals (Sweden)

    N. Hoffmann

    2013-04-01

    Full Text Available Heterogeneous nucleation of ice in a supercooled water droplet induced by an external contact with a dry aerosol particle has long been known to be more effective than freezing induced by the same nucleus immersed in the droplet. However, the experimental quantification of contact freezing is challenging. Here we report an experimental method allowing to determine the temperature dependent ice nucleation probability of size selected aerosol particles. The method uses supercooled charged water droplets suspended in a laminar flow of air containing aerosol particles as contact freezing nuclei. The rate of droplet–particle collisions is calculated numerically with account for Coulomb attraction, drag force and induced dipole interaction between charged droplet and aerosol particles. The calculation is verified by direct counting of aerosol particles collected by a levitated droplet. By repeating the experiment on individual droplets for a sufficient number of times, we are able to reproduce the statistical freezing behavior of a large ensemble of supercooled droplets and measure the average rate of freezing events. The freezing rate is equal to the product of the droplet–particle collision rate and the probability of freezing on a single contact, the latter being a function of temperature, size and composition of the contact ice nuclei. Based on these observations, we show that for the types of particles investigated so far, contact freezing is the dominating freezing mechanism on the time scale of our experiment.

  14. Experimental quantification of contact freezing in an electrodynamic balance

    Directory of Open Access Journals (Sweden)

    N. Hoffmann

    2013-09-01

    Full Text Available Heterogeneous nucleation of ice in a supercooled water droplet induced by external contact with a dry aerosol particle has long been known to be more effective than freezing induced by the same nucleus immersed in the droplet. However, the experimental quantification of contact freezing is challenging. Here we report an experimental method to determine the temperature-dependent ice nucleation probability of size-selected aerosol particles. The method is based on the suspension of supercooled charged water droplets in a laminar flow of air containing aerosol particles as contact freezing nuclei. The rate of droplet–particle collisions is calculated numerically with account for Coulomb attraction, drag force and induced dipole interaction between charged droplet and aerosol particles. The calculation is verified by direct counting of aerosol particles collected by a levitated droplet. By repeating the experiment on individual droplets for a sufficient number of times, we are able to reproduce the statistical freezing behavior of a large ensemble of supercooled droplets and measure the average rate of freezing events. The freezing rate is equal to the product of the droplet–particle collision rate and the probability of freezing on a single contact, the latter being a function of temperature, size and composition of the contact ice nuclei. Based on these observations, we show that for the types of particles investigated so far, contact freezing is the dominating freezing mechanism on the timescale of our experiment.

  15. Study on Freeze-drying Process of Dumpling Wrappers

    OpenAIRE

    Wanren Chen; Hua Li; Xingli Jiao; Xiang Gui

    2015-01-01

    The freeze-drying process of frozen dumpling wrappers is studied in this study. And the effects of drying time, drying temperature and the capacity of unit area in the freezing process on the drying rate and rehydration rate of freeze-drying dumpling wrappers are investigated. The result shows that, in the process of freeze-drying dumpling wrappers, the optimal condition is: drying time is 3 h, drying temperature is 45°C and the loadage of per unit area is 4.0 kg/m2.

  16. A“TIME-SPACE” RELATED DESIGNMETHOD OF FREEZING WALL

    Institute of Scientific and Technical Information of China (English)

    陈湘生

    1996-01-01

    Artificially ground freezing (AGF) is one of the main methods to establish temporarysupport for shaft sinking in unstable water bearing strata. Domde (1915) formula based on frozensoil strength has widely been used for designing freezing wall thickness. However, it can not en-sure the stability of freezing wall, nor guarantee the safety of shaft construction as frozen depth in-creases in unstable water bearing strata. F. A. Auld (1985, 1988)[1'2] presented a designmethod of freezing wall, which is on the basis of strength and stability, together with deformationof freezing wall. This paper, according to the practice in China, describes a "time -space" relat-ed design method for deep freezing wall. The method is based on "time-space" concept, whichincludes influence of excavation rate of advance, unsupported length of freezing wall and the sumpstate on inward deformation of freezing wall, and the allowable pipe deformation caused by in-ward deformation of freezing wall. Finally, successful application of this method to the large scalecoal mine-Jining No. 2 Mine[3] in Shandong Province of China is presented. It saved much invest-ment compared with F. A. Auld's design for the same mine.

  17. Study on Freeze-drying Process of Dumpling Wrappers

    Directory of Open Access Journals (Sweden)

    Wanren Chen

    2015-06-01

    Full Text Available The freeze-drying process of frozen dumpling wrappers is studied in this study. And the effects of drying time, drying temperature and the capacity of unit area in the freezing process on the drying rate and rehydration rate of freeze-drying dumpling wrappers are investigated. The result shows that, in the process of freeze-drying dumpling wrappers, the optimal condition is: drying time is 3 h, drying temperature is 45°C and the loadage of per unit area is 4.0 kg/m2.

  18. Parameter Sensitivity of the Microdroplet Vacuum Freezing Process

    Directory of Open Access Journals (Sweden)

    Zhijun Zhang

    2015-01-01

    Full Text Available The vacuum freezing process of microdroplets (1 mm. Pressure and droplet diameter have an effect on cooling and freezing stages, but initial temperature only affects the cooling stage. The thermal conductivity coefficient kl affected the cooling stage, whereas ki affected the freezing stage. Heat capacity Cl affected the cooling stage, but Ci has virtually no effect on all stages. The actual latent heat of freezing ΔH was also affected. Higher density corresponds to lower cooling rate in the cooling stage.

  19. Freezing of water droplets colliding with kaolinite particles

    DEFF Research Database (Denmark)

    Svensson, Erik Anders; Delval, Christophe Eric Ludovic; Freiherr von Und zu Hessberg, P J H;

    2009-01-01

    Contact freezing of single supercooled water droplets colliding with kaolinite dust particles has been investigated. The experiments were performed with droplets levitated in an electrodynamic balance at temperatures from 240 to 268 K. Under dry conditions freezing 5 was observed to occur below 249...... K, while a freezing threshold of 267 K was observed at high relative humidity. The effect of relative humidity is attributed to an influence on the contact freezing process for the kaolinite-water droplet system, and it is not related to the lifetime of the droplets in the electrodynamic balance...

  20. X-ray microanalysis of calcium in ischemic myocardium: a new method of rapid freezing.

    Science.gov (United States)

    Sybers, H D; Myre, C D; Myre, M V

    1983-01-01

    X-ray microanalysis of biological material is best accomplished on unfixed frozen tissue sectioned on a cryoultramicrotome. The need for ultra-rapid freezing to minimize ice crystal artifact has been well documented but is difficult to achieve without the use of potentially hazardous Isopentane or Freon 22 in liquid nitrogen slush. In the present study we employ a slurry of powdered graphite in liquid nitrogen to obtain rapid freezing of cardiac tissue. The results obtained were as good as those which are achieved with Freon 22 in liquid nitrogen, and subsequent cryoultramicrotomy produced thin sections relatively free of ice crystal artifact. Microanalysis revealed a slight increase in mitochondrial calcium as compared with cytoplasmic calcium in normal myocytes. Mitochondrial calcium concentration rose significantly after 30 min of ischemia while only a slight rise in cytoplasmic calcium occurred. These findings suggest that the techniques employed are adequate for detecting ion shifts which occur during ischemia and may be useful for determining the effects of therapeutic agents at the organellar level. PMID:6635573