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Sample records for chemically defined freezing

  1. Chemical Freeze-Out and Higher Order Multiplicity Moments

    CERN Document Server

    Tawfik, A

    2013-01-01

    We calculate the non-normalized moments of the particle multiplicity within the framework of the hadron resonance gas (HRG) model. At finite chemical potential $\\mu$, a non-monotonic behavior is observed in the thermal evolution of third order moment (skewness $S$) and the higher order ones as well. Among others, this observation likely reflects dynamical fluctuations and strong correlations. The signatures of non-monotonicity in the normalized fourth order moment (kurtosis $\\kappa$) and its products get very clear. Based on these findings, we introduce a novel condition characterizing the universal freeze-out curve. The chemical freeze-out parameters $T$ and $\\mu$ are described by vanishing $\\kappa\\, \\sigma^2$ or equivalently $m_4=3\\,\\chi^2$, where $\\sigma$, $\\chi$ and $m_4$ are the standard deviation, susceptibility and fourth order moment, respectively. The fact that the HRG model is not able to release information about criticality related to the confinement and chiral dynamics should not veil the observa...

  2. Chemical freeze-out and higher order multiplicity moments

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, A., E-mail: a.tawfik@eng.mti.edu.eg

    2014-02-15

    We calculate the non-normalized moments of the particle multiplicity within the framework of the hadron resonance gas (HRG) model. At finite chemical potential μ, a non-monotonic behavior is observed in the thermal evolution of third order moment (skewness S) and the higher order ones as well. The signatures of non-monotonicity in the normalized fourth order moment (kurtosis κ) and its products get very clear. Among others, this observation likely reflects dynamical fluctuations and strong correlations. Based on these findings, we introduce the physics of the universal freeze-out curve. It is found that the chemical freeze-out parameters T and μ are described by vanishing κσ{sup 2} or equivalently m{sub 4}=3χ{sup 2}, where σ, χ and m{sub 4} are the standard deviation, susceptibility and fourth order moment, respectively. The fact that the HRG model is not able to release information about criticality related to the confinement and chiral dynamics should not veil the observations related to the chemical freeze-out. Recent lattice QCD studies strongly advocate the main conclusion of the present paper.

  3. Chemically defined medium and Caenorhabditis elegans

    Science.gov (United States)

    Szewczyk, Nathaniel J.; Kozak, Elena; Conley, Catharine A.

    2003-01-01

    BACKGROUND: C. elegans has been established as a powerful genetic system. Use of a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of use in large-scale growth and screening of animals. RESULTS: We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats to using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change the composition of the defined medium. CONCLUSIONS: As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

  4. Strangeness enhancement at the hadronic chemical freeze-out

    CERN Document Server

    Sagun, V V; Bugaev, K A; Cleymans, J; Ivanytskyi, A I; Mishustin, I N; Nikonov, E G

    2014-01-01

    The chemical freeze-out of hadrons created in the high energy nuclear collisions is studied within the realistic version of the hadron resonance gas model. The chemical non-equilibrium of strange particles is accounted via the usual $\\gamma_{s}$ factor which gives us an opportunity to perform a high quality fit with $\\chi^2/dof \\simeq 63.5/55 \\simeq 1.15$ of the hadronic multiplicity ratios measured from the low AGS to the highest RHIC energies. In contrast to previous findings, at low energies we observe the strangeness enhancement instead of a suppression. In addition, the performed $\\gamma_{s}$ fit allows us to achieve the highest quality of the Strangeness Horn description with $\\chi^2/dof=3.3/14$. For the first time the top point of the Strangeness Horn is perfectly reproduced, which makes our theoretical horn as sharp as an experimental one. However, the $\\gamma_{s}$ fit approach does not sizably improve the description of the multi-strange baryons and antibaryons. Therefore, an apparent deviation of mu...

  5. A chemically defined medium for rabbit embryo cryopreservation.

    Directory of Open Access Journals (Sweden)

    Pierre Bruyère

    = 0.066. We conclude that CRYO3 can be used as a chemically defined substitute for animal-based products in rabbit embryo cryopreservation solutions.

  6. Compressive Strength, Chloride Permeability, and Freeze-Thaw Resistance of MWNT Concretes under Different Chemical Treatments

    Directory of Open Access Journals (Sweden)

    Xingang Wang

    2014-01-01

    Full Text Available This study investigated compressive strength, chloride penetration, and freeze-thaw resistance of multiwalled carbon nanotube (MWNT concrete. More than 100 cylindrical specimens were used to assess test variables during sensitivity observations, including water-cement ratios (0.75, 0.5, and 0.4 and exposure to chemical agents (including gum arabic, propanol, ethanol, sodium polyacrylate, methylcellulose, sodium dodecyl sulfate, and silane. To determine the adequate sonication time for MWNT dispersal in water, the compressive strengths of MWNT concrete cylinders were measured after sonication times ranging from 2 to 24 minutes. The results demonstrated that the addition of MWNT can increase the compressive strength of concrete by up to 108%. However, without chemical treatment, MWNT concretes tend to have poor freeze-thaw resistance. Among the different chemical treatments, MWNT concrete treated with sodium polyacrylate has the best compressive strength, chloride resistance, and freeze-thaw durability.

  7. Freeze-thaw performance of chemically stabilized natural and recycled highway materials

    Institute of Scientific and Technical Information of China (English)

    Tuncer B Edil; Bora Cetin

    2015-01-01

    This article provides an overview of several previous studies that investigated the stiffness and strength performance of chemically stabilized roadway materials under winter conditions (freeze-thaw cycling). The objective of this research was to understand the behavior of different materials stabilized with different type of binders when they were subjected to freeze-thaw cycling. Nine different materials including natural soils (organic soil, clay, silt, sand, and road surface gravel), reclaimed pavement material, and recycled asphalt pavement stabilized with nine different binders (five different fly ashes, lime, cement, lime kiln dust, cement kiln dust) were discussed. This article investigated how the volume, resilient modulus and unconfined compressive strength of soils/materials stabilized with different binders change in response to freeze-thaw cycling. Overall, the review results indicate that the stiffness and strength of all stabilized materials decrease somewhat with freeze-thaw cycling. However, the reduced strength and stiffness of stabilized materials after freeze-thaw cycling was still higher than that of unstabilized-unfrozen original soils and materials. In addition, materials stabilized with cement kiln dust provided the best performance against freeze-thaw cycling.

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

    Science.gov (United States)

    Fukushima, Kenji; Hidaka, Yoshimasa

    2016-09-01

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

  9. On the Higher Moments of Particle Multiplicity, Chemical Freeze-Out, and QCD Critical Endpoint

    Directory of Open Access Journals (Sweden)

    A. Tawfik

    2013-01-01

    Full Text Available We calculate the first six nonnormalized moments of particle multiplicity within the framework of the hadron resonance gas model. In terms of the lower order moments and corresponding correlation functions, general expressions of higher order moments are derived. Thermal evolution of the first four normalized moments and their products (ratios are studied at different chemical potentials, so that it is possible to evaluate them at chemical freeze-out curve. It is found that a nonmonotonic behaviour reflecting the dynamical fluctuation and strong correlation of particles starts to appear from the normalized third order moment. We introduce novel conditions for describing the chemical freeze-out curve. Although the hadron resonance gas model does not contain any information on the criticality related to the chiral dynamics and singularity in the physical observables, we are able to find out the location of the QCD critical endpoint at μ ~ 350  MeV and temperature T ~ 162  MeV.

  10. Energy and centrality dependence of chemical freeze-out parameters from models

    CERN Document Server

    Kumar, Lokesh

    2013-01-01

    One of the main goals of heavy-ion collision experiments is to study the structure of the QCD phase diagram. The QCD phase diagram is typically plotted as temperature ($T$) vs. baryon chemical potential ($\\mu_{B}$). The statistical thermal model THERMUS compared to experimental data provides chemical freeze-out parameters such as temperature, baryon chemical potential and strangeness saturation factor ($\\gamma_{s}$). However, the values of these parameters depend on models and their underlying assumptions, such as the nature of the ensemble used, particle ratios vs. particle yields, and the treatment of feed-down contributions to particle yields. In these proceedings, we report on a systematic study of chemical freeze-out parameters using THERMUS, as a function of collision centrality and collision energies ($\\sqrt{s_{NN}} =7.7-200$ GeV). These studies are performed with the string melting version of A Multi-Phase Transport (AMPT) model. A comparison is presented of freeze-out parameters between grand-canonic...

  11. Chemically Defined Medium and Caenorhabditis elegans: A Powerful Approach

    Science.gov (United States)

    Szewczyk, N. J.; Kozak, E.; Conley, C. A.

    2003-01-01

    C. elegans has been established as a powerful genetic system. Growth in a chemically defined medium (C. elegans Maintenance Medium (CeMM)) now allows standardization and systematic manipulation of the nutrients that animals receive. Liquid cultivation allows automated culturing and experimentation and should be of me in large-scale growth and screening of animals. Here we present our initial results from developing culture systems with CeMM. We find that CeMM is versatile and culturing is simple. CeMM can be used in a solid or liquid state, it can be stored unused for at least a year, unattended actively growing cultures may be maintained longer than with standard techniques, and standard C. elegans protocols work well with animals grown in defined medium. We also find that there are caveats of using defined medium. Animals in defined medium grow more slowly than on standard medium, appear to display adaptation to the defined medium, and display altered growth rates as they change defined medium composition. As was suggested with the introduction of C. elegans as a potential genetic system, use of defined medium with C. elegans should prove a powerful tool.

  12. Net-charge probability distributions in heavy ion collisions at chemical freeze-out

    CERN Document Server

    Braun-Munzinger, P; Karsch, F; Redlich, K; Skokov, V

    2011-01-01

    We explore net charge probability distributions in heavy ion collisions within the hadron resonance gas model. The distributions for strangeness, electric charge and baryon number are derived. We show that, within this model, net charge probability distributions and the resulting fluctuations can be computed directly from the measured yields of charged and multi-charged hadrons. The influence of multi-charged particles and quantum statistics on the shape of the distribution is examined. We discuss the properties of the net proton distribution along the chemical freeze-out line. The model results presented here can be compared with data at RHIC energies and at the LHC to possibly search for the relation between chemical freeze-out and QCD cross-over lines in heavy ion collisions.

  13. PREPARATION OF CHEMICALLY WELL-DEFINED CARBOHYDRATE DENDRIMER CONJUGATES

    DEFF Research Database (Denmark)

    2004-01-01

    A method for the synthesis of dendrimer conjugates having a well-defined chemical structure, comprising one or more carbohydrate moieties and one or more immunomodulating substances coupled to a dendrimer, is presented. First, the carbohydrate is bound to the dendrimer in a chemoselective manner....... Subsequently, the immunomodulating substance is also bound in a chemoselective manner, to give a dendrimer conjugate with a well-defined structure and connectivity and containing a precise, pre-determined ratio of carbohydrate to immunomodulating substance. The invention also relates to novel dendrimer...

  14. Hadron yields, the chemical freeze-out and the QCD phase diagram

    CERN Document Server

    Andronic, A; Redlich, K; Stachel, J

    2016-01-01

    We present the status of the chemical freeze-out, determined from fits of hadron yields with the statistical hadronization (thermal) model, with focus on the data at the LHC. A description of the yields of hadrons containing light quarks as well as the application of the model for the production of the J/$\\psi$ meson is presented. The implications for the QCD phase diagram are discussed.

  15. Effects of Chemical Aging on the Heterogeneous Freezing of Organic Aerosols

    Science.gov (United States)

    Collier, K.; Brooks, S. D.

    2014-12-01

    Organic aerosols are emitted into the atmosphere from a variety of sources and display a wide range of effectiveness in promoting the nucleation of ice in clouds. Soot and polycyclic aromatic hydrocarbons (PAHS) arise from incomplete combustion and other pollutant sources. Hydrocarbon compounds in diesel motor oil and other fuel blends include compounds such as octacosane (a straight saturated alkane), squalane (a branched saturated alkane) and squalene (an unsaturated branched alkene). At temperatures above -36°C, the formation of ice crystals in the atmosphere is facilitated by heterogeneous freezing processes in which atmospheric aerosols act as ice nuclei (IN). The variability in ability of organic particles to facilitate heterogeneous ice nucleation causes major uncertainties in predictions of aerosol effects on climate. Further, atmospheric aerosol composition and ice nucleation ability can be altered via chemical aging and reactions with atmospheric oxidants such as ozone. In this study, we take a closer look at the role of chemical oxidation on the efficiency of specific IN during contact freezing laboratory experiments. The freezing temperatures of droplets in contact with representative organic aerosols are determined through the use of an optical microscope apparatus equipped with a cooling stage and a digital camera. Chemical changes at the surface of aerosols due to ozone exposure are characterized using Raman Microspectroscopy and Fourier Transform Infrared Spectroscopy with Horizontal Attenuated Total Reflectance. Our results indicate that oxidation of certain atmospheric organics (soot and PAHS) enhances their ice nucleation ability. In this presentation, results of heterogeneous nucleation on various types of organic aerosols will be presented, and the role of structure in promoting freezing will be discussed.

  16. Optimizing the Chemical Compositions of Protective Agents for Freeze-drying Bifidobacterium longum BIOMA 5920

    Institute of Scientific and Technical Information of China (English)

    杨婵媛; 朱晓丽; 范代娣; 米钰; 骆艳娥; 惠俊峰; 苏然

    2012-01-01

    Freeze drying has a deleterious effect on the viability of microorganisms. In front of this difficulty, the present study adopts response surface methodology to optimize the chemical compositions of protective agents to seek for maximum viability of Bifidobacterium longum BIOMA 5920 during freeze-drying. Through the compara- tive analysis of single protectant, the complex protective agents show better effect on the Bifidobacterium viability. Human-like collagen (HLC), trehalose and glycerol are confirmed as significant factors by Box-Behnken Design. The optimized formula for these three variables is tested as follows: HLC 1.23%, trehalose 11.50% and glycerol 4.65%. Under this formula, the viability is 88.23%, 39.67% higher in comparison to the control. The viable count is 1.07×10 9 cfu·g-1 , greatly exceeding the minimum viable count requirement (10 6 cfu·g-1 ).

  17. Nutritional models for space travel from chemically defined diets

    Science.gov (United States)

    Dufour, P. A.

    1984-01-01

    Human nutritional requirements are summarized, including recommended daily intake and maximum safe chronic intake of nutrients. The biomedical literature on various types of chemically defined diets (CDD's), which are liquid, formulated diets for enteral and total parenteral nutrition, is reviewed. The chemical forms of the nutrients in CDD's are detailed, and the compositions and sources of representative commercial CDD's are tabulated. Reported effects of CDD's in medical patients, healthy volunteers, and laboratory animals are discussed. The effects include gastrointestinal side effects, metabolic imbalances, nutrient deficiencies and excesses, and psychological problems. Dietary factors contributing to the side effects are examined. Certain human nutrient requirements have been specified more precisely as a result of long-term use of CDD's, and related studies are included. CDD's are the most restricted yet nutritionally complete diets available.

  18. Chemical freeze-out in Hawking-Unruh radiation and quark-hadron transition

    CERN Document Server

    Tawfik, Abdel Nasser; Elyazeed, Eman R Abo

    2015-01-01

    The proposed analogy between hadron production in high-energy collisions and Hawking-Unruh radiation process in the black holes shall be extended. This mechanism provides a theoretical basis for the freeze-out parameters, the temperature ($T$) and the baryon chemical potential ($\\mu$), characterizing the final state of particle production. The results from charged black holes, in which the electric charge is related to $\\mu$, are found comparable with the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in thermal statistical models and Polyakov linear-sigma model. Furthermore, the resulting freeze-out condition $\\langle E\\rangle/\\langle N\\rangle\\simeq 1~$GeV for average energy per particle is in good agreement with the hadronization process in the high-energy experiments. For the entropy density ($s$), the freeze-out condition $s/T^3\\simeq7$ remains valid for $\\mu\\lesssim 0.3~$GeV. Then, due to the dependence of $T$ on $...

  19. Automated Discovery of Elementary Chemical Reaction Steps Using Freezing String and Berny Optimization Methods.

    Science.gov (United States)

    Suleimanov, Yury V; Green, William H

    2015-09-08

    We present a simple protocol which allows fully automated discovery of elementary chemical reaction steps using in cooperation double- and single-ended transition-state optimization algorithms--the freezing string and Berny optimization methods, respectively. To demonstrate the utility of the proposed approach, the reactivity of several single-molecule systems of combustion and atmospheric chemistry importance is investigated. The proposed algorithm allowed us to detect without any human intervention not only "known" reaction pathways, manually detected in the previous studies, but also new, previously "unknown", reaction pathways which involve significant atom rearrangements. We believe that applying such a systematic approach to elementary reaction path finding will greatly accelerate the discovery of new chemistry and will lead to more accurate computer simulations of various chemical processes.

  20. Automated Discovery of Elementary Chemical Reaction Steps Using Freezing String and Berny Optimization Methods

    CERN Document Server

    Suleimanov, Yury V

    2015-01-01

    We present a simple protocol which allows fully automated discovery of elementary chemical reaction steps using in cooperation single- and double-ended transition-state optimization algorithms - the freezing string and Berny optimization methods, respectively. To demonstrate the utility of the proposed approach, the reactivity of several systems of combustion and atmospheric chemistry importance is investigated. The proposed algorithm allowed us to detect without any human intervention not only "known" reaction pathways, manually detected in the previous studies, but also new, previously "unknown", reaction pathways which involve significant atom rearrangements. We believe that applying such a systematic approach to elementary reaction path finding will greatly accelerate the possibility of discovery of new chemistry and will lead to more accurate computer simulations of various chemical processes.

  1. On the Higher Moments of Particle Multiplicity, Chemical Freeze-Out and QCD Critical Endpoint

    CERN Document Server

    Tawfik, A

    2012-01-01

    We calculate the first six non-normalized moments of particle multiplicity within the hadron resonance gas model. In terms of lower moments, general expressions for arbitrary higher moments are deduced, so that it is concluded that going from lower to higher moments is achievable through a series of lower moments and correlation functions. The thermal evolution of the first four normalized moments and their products (ratios) are studied at different chemical potentials $\\mu$, so that it was possible to evaluate them at the chemical freeze-out curve, which is characterized by constant $s/T^3$ at all values of $\\mu$, where $s$ and $T$ are entropy density and temperature, respectively. It has been found that non-monotonic behavior reflecting dynamical fluctuation and strong correlations appears starting from the normalized third moment (skewness $S$). The signatures of non-monotonicity in the normalized fourth moment (kurtosis $\\kappa$) and its products are very clear. Based on these findings, we introduce novel...

  2. Effect of high doses of chemical admixtures on the strength development and freeze-thaw durability of portland cement mortar

    Science.gov (United States)

    Korhonen, Charles J.

    This thesis examines the low-temperature strength development of portland cement concrete made with high doses of chemical admixtures dissolved in the mixing water and the possible beneficial effect of these admixtures on that concrete's long-term freeze-thaw durability. The literature shows that high doses of chemical admixtures can protect fresh concrete against freezing and that, under certain conditions, these admixtures can enhance the freeze-thaw durability of concrete. The challenge is that there are no acceptance standards in the U.S. that allow chemicals to be used to protect concrete against freezing. Also, the perception is that chemicals might somehow harm the concrete. This perception seems to be based on the fact that deicing salts, when applied to concrete pavement, cause roadways to scale away. This study investigated the effect of high doses of commercially available admixtures on fresh concrete while it gained strength at low temperature and on hardened concrete exposed to repeated cycles of freezing and thawing in a moist environment. The reason for studying off-the-shelf admixtures was that these materials are approved for use in concrete; they were already governed by their own set of standards. Four mortars were examined, each with a different cement and water content, when dosed with five commercial admixtures. This allowed the fresh mortar to gain appreciable strength when it was kept at nearly -10C. The admixtures also enhanced the freeze-thaw durability of the mortar, even when it was not air-entrained. Clearly, as the dosage of admixture increased beyond approximately 22% by weight of water, the mortar appeared to be unaffected by up to 700 cycles of freezing and thawing.

  3. Chemically defined media modifications to lower tryptophan oxidation of biopharmaceuticals.

    Science.gov (United States)

    Hazeltine, Laurie B; Knueven, Kristine M; Zhang, Yan; Lian, Zhirui; Olson, Donald J; Ouyang, Anli

    2016-01-01

    Oxidation of biopharmaceuticals is a major product quality issue with potential impacts on activity and immunogenicity. At Eli Lilly and Company, high tryptophan oxidation was observed for two biopharmaceuticals in development produced in Chinese hamster ovary cells. A switch from historical hydrolysate-containing media to chemically defined media with a reformulated basal powder was thought to be responsible, so mitigation efforts focused on media modification. Shake flask studies identified that increasing tryptophan, copper, and manganese and decreasing cysteine concentrations were individual approaches to lower tryptophan oxidation. When amino acid and metal changes were combined, the modified formulation had a synergistic impact that led to substantially less tryptophan oxidation for both biopharmaceuticals. Similar results were achieved in shake flasks and benchtop bioreactors, demonstrating the potential to implement these modifications at manufacturing scale. The modified formulation did not negatively impact cell growth and viability, product titer, purity, charge variants, or glycan profile. A potential mechanism of action is presented for each amino acid or metal factor based on its role in oxidation chemistry. This work served not only to mitigate the tryptophan oxidation issue in two Lilly biopharmaceuticals in development, but also to increase our knowledge and appreciation for the impact of media components on product quality.

  4. Parameter-free determination of actual temperature at chemical freeze-out in nuclear interactions

    Science.gov (United States)

    Panagiotou, A. D.; Mavromanolakis, G.; Tzoulis, J.

    1995-07-01

    We propose a method to determine the actual temperature at chemical freeze-out in relativistic nucleus-nucleus collisions, using the experimental μq/T and μs/T values, obtained from strange particle ratios. We employ the Hadron Gas formalism, assuming only local thermal equilibration, to relate the quarkchemical potential and temperature. This relation constrains the allowed values of μq/T, μs/T and T, enabling the determination of the actual temperature. Comparison of the inverse slope parameter of the mT-distributions with the actual temperature determines the transverse flow velocity of the fireball matter. Knowledge of these quantities is essential in determining the EoS of nuclear matter and in evaluating interactions with regard to a possible phase transition to QGP.

  5. Fracturing and Damage to Sandstone Under Coupling Effects of Chemical Corrosion and Freeze-Thaw Cycles

    Science.gov (United States)

    Han, Tielin; Shi, Junping; Cao, Xiaoshan

    2016-11-01

    Rapid freeze-thaw (FT) cycles were adopted to explore the damage deterioration mechanism and mechanical properties of sandstone specimens under the coupling effects of different chemical solutions and FT cycles. The variation regularities of the FT cycles and physical and mechanical properties of sandstone specimens immersed in different chemical solutions were analyzed by using sandstone sampled from a Chinese riverbank slope. The damage variable based on porosity variation was used in the quantitative analysis of the damage to the sandstone under the coupling effects of chemical corrosion and FT cycles. Experimental results showed that the sandstone specimens weakened substantially under those effects. Their fracture toughness K IC, splitting tensile strength, and compressive strength showed a similar deteriorating trend with various numbers of FT cycles. However, a difference exists in the deterioration degree of their mechanical parameters, i.e., the deterioration degree of their fracture toughness K IC is the greatest followed by that of splitting tensile strength, and that of compressive strength is relatively small. Strong acid solutions may aggravate the deterioration of FT damage in sandstones, but at the early stage of the experiment, strong alkaline solutions inhibited sandstone damage deterioration. However, the inhibiting effect disappeared when the number of FT cycles exceeded 25. The different chemical solutions had a different effect on the FT damage degree of the sandstone specimens; for example, SO4 2- ions had a greater effect on FT damage than did HCO3 - ions. Water-chemical solutions and FT cycles promote each other in deteriorating rocks and simultaneously affect the damage deterioration degree of sandstones.

  6. The Effects of Freezing and Supplementation of Molasses and Inoculants on Chemical and Nutritional Composition of Sunflower Silage.

    Science.gov (United States)

    Konca, Y; Beyzi, S Buyukkilic; Ayaşan, T; Kaliber, M; Kiraz, A Bozkurt

    2016-07-01

    This study was conducted to determine the effects of freezing and supplementation of molasses (M), lactic acid bacteria (LAB) and LAB+enzyme mixture on chemical and nutritional composition of sunflower silage (SF). Sunflower crops were harvested (at about 29.2%±1.2% dry matter) and half of fresh sunflower was ensiled alone and half was frozen (F) at -20°C for 7 days. Silage additives were admixed into frozen SF material. All samples were ensiled in glass jars with six replicates for 90 days. The treatments were as follows: i) positive control (non-frozen and no additives, NF), ii) negative control (frozen, no additives, F), iii) F+5% molasses (FM), iv) F+LAB (1.5 g/tons, Lactobacillus plantarum and Enterococcus faecium, FLAB); v) F+LAB+enzyme (2 g/tons Lactobacillus plantarum and Enterococcus faecium and cellulase and amylase enzymes, FLEN). Freezing silage increased dry matter, crude ash, neutral detergent fiber, and acid detergent lignin. The organic matter, total digestible nutrient, non-fiber carbohydrate, metabolizable energy and in vitro dry matter digestibility were negatively influenced by freezing treatments (p<0.05). In conclusion, freezing sunflower plants prior to ensiling may negatively affect silage quality, while molasses supplementation improved some quality traits of frozen silage. Lactic acid bacteria and LAB+enzyme inoculations did not effectively compensate the negative impacts of freezing on sunflower silage.

  7. Defining food sampling strategy for chemical risk assessment

    OpenAIRE

    Wesolek, Nathalie; Roudot, Alain-Claude

    2012-01-01

    International audience; Collection of accurate and reliable data is a prerequisite for informed risk assessment and risk management. For chemical contaminants in food, contamination assessments enable consumer protection and exposure assessments. And yet, the accuracy of a contamination assessment depends on both chemical analysis and sampling plan performance. A sampling plan is always used when the contamination level of a food lot is evaluated, due to the fact that the whole lot can not be...

  8. A non-equilibrium picture of the chemical freeze-out in hadronic thermal models

    CERN Document Server

    De Assis, Leonardo P G; Chiapparini, Marcelo; Hirsch, Luciana R; Delfino, Antonio

    2012-01-01

    Thermal models have proven to be an useful and simple tool used to make theoretical predictions and data analysis in relativistic and ultra-relativistic heavy ion collisions. A new version of these models is presented here, incorporating a non equilibrium feature to the description of the intermediate fireball state formed at the chemical freeze-out. Two different effective temperatures are attributed to the expanding fireball, regarding its baryonic and mesonic sectors. The proposal is not merely to include an additional degree of freedom to reach a better adjustment to the data, but to open a room in the model conception for considerations on the non-equilibrium scenario of the system evolution. A set of well consolidated data for particles production is used to validated the reformulated version of thermal models presented here. A rather good performance of the extended version was verified, both for the quality of particle ratio data fittings as well as for describing the asymptotic energy behavior of tem...

  9. The Effects of Freezing and Supplementation of Molasses and Inoculants on Chemical and Nutritional Composition of Sunflower Silage

    Science.gov (United States)

    Konca, Y.; Beyzi, S. Buyukkilic; Ayaşan, T.; Kaliber, M.; Kiraz, A. Bozkurt

    2016-01-01

    This study was conducted to determine the effects of freezing and supplementation of molasses (M), lactic acid bacteria (LAB) and LAB+enzyme mixture on chemical and nutritional composition of sunflower silage (SF). Sunflower crops were harvested (at about 29.2%±1.2% dry matter) and half of fresh sunflower was ensiled alone and half was frozen (F) at −20°C for 7 days. Silage additives were admixed into frozen SF material. All samples were ensiled in glass jars with six replicates for 90 days. The treatments were as follows: i) positive control (non-frozen and no additives, NF), ii) negative control (frozen, no additives, F), iii) F+5% molasses (FM), iv) F+LAB (1.5 g/tons, Lactobacillus plantarum and Enterococcus faecium, FLAB); v) F+LAB+enzyme (2 g/tons Lactobacillus plantarum and Enterococcus faecium and cellulase and amylase enzymes, FLEN). Freezing silage increased dry matter, crude ash, neutral detergent fiber, and acid detergent lignin. The organic matter, total digestible nutrient, non-fiber carbohydrate, metabolizable energy and in vitro dry matter digestibility were negatively influenced by freezing treatments (psilage quality, while molasses supplementation improved some quality traits of frozen silage. Lactic acid bacteria and LAB+enzyme inoculations did not effectively compensate the negative impacts of freezing on sunflower silage. PMID:26954197

  10. A Pilot Study To Define Chemical Coping in Cancer Patients Using the Delphi Method

    OpenAIRE

    Kwon, Jung Hye; Hui, David; Bruera, Eduardo

    2015-01-01

    Background: “Chemical coping” is a commonly used term in the pain and palliative care literature, but is heterogeneously defined. We conducted a Delphi survey among palliative care and pain specialists internationally to identify a consensus definition for “chemical coping with opioids” and warning signs for chemical coping.

  11. Basic concepts in freezing cells

    Energy Technology Data Exchange (ETDEWEB)

    Mazur, P.

    1985-01-01

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

  12. 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.

  13. Chemical freeze-out in ultrarelativistic heavy ion collisions at sNN=130 and 200 GeV

    Science.gov (United States)

    Manninen, J.; Becattini, F.

    2008-11-01

    A comprehensive and detailed analysis of hadronic abundances measured in Au-Au collisions at RHIC at sNN=130 and 200 GeV is presented. The rapidity densities measured in the central rapidity region have been fitted to the statistical hadronization model and the chemical freeze-out parameters determined as a function of centrality, using data from experiments BRAHMS, PHENIX, and STAR. The chemical freeze-out temperature turns out to be independent of centrality to accuracy of a few percentages, whereas the strangeness undersaturation parameter γS decreases from almost unity in central collisions to a significantly lower value in peripheral collisions. Our results are in essential agreement with previous analyses, with the exception that fit quality at sNN=200 GeV is not as good as previously found. From the comparison of the two different energies, we conclude that the difference in fit quality, as described by χ2 values, is owing to the improved resolution of measurements that has probably exceeded the intrinsic accuracy of the simplified theoretical formula used in the fits.

  14. Constant Trace Anomaly as a Universal Condition for the Chemical Freeze-Out

    CERN Document Server

    Tawfik, A

    2013-01-01

    Finding out universal conditions describing the freeze-out parameters was a subject of various phenomenological studies. In the present work, we introduce a new condition based on constant trace anomaly (or interaction measure) calculated in the hadron resonance gas (HRG) model. Various extensions to the {\\it ideal} HRG which are conjectured to take into consideration different types of interactions have been analysed. When comparing HRG thermodynamics to that of lattice quantum chromodynamics, we conclude that the hard-core radii are practically irrelevant, especially when HRG includes all resonances with masses less than $2~$GeV. It is found that the constant trace anomaly (or interaction measure) agrees well with most of previous conditions.

  15. Separate chemical freeze-outs of strange and non-strange hadrons and problem of residual chemical non-equilibrium of strangeness in relativistic heavy ion collisions

    CERN Document Server

    Bugaev, K A; Sagun, V V; Ivanytskyi, A I; Cleymans, J; Mironchuk, E S; Nikonov, E G; Taranenko, A V; Zinovjev, G M

    2016-01-01

    We present an elaborate version of the hadron resonance gas model with the combined treatment of separate chemical freeze-outs for strange and non-strange hadrons and with an additional $\\gamma_{s}$ factor which accounts for the remaining strange particle non-equilibration. Within suggested approach the parameters of two chemical freeze-outs are connected by the conservation laws of entropy, baryonic charge, third isospin projection and strangeness. The developed model enables us to perform a high-quality fit of the hadron multiplicity ratios measured at AGS, SPS and RHIC with $\\chi^2/dof \\simeq 0.93$. A special attention is paid to a successful description of the Strangeness Horn. The well-known problem of selective suppression of $\\bar \\Lambda $ and $\\bar \\Xi$ hyperons is also discussed. The main result is that for all collision energies the $\\gamma_{s}$ factor is about 1 within the error bars, except for the center of mass collision energy 7.6 GeV at which we find about 20\\% enhancement of strangeness. Als...

  16. LIQUID NITROGEN PRESERVATION OF MAMMALIAN CELLS IN A CHEMICALLY DEFINED MEDIUM AND DIMETHYLSULFOXIDE

    Science.gov (United States)

    Three established mammalian cell lines (cat kidney, L, and HeLa cells ) grown in suspension in a protein-free chemically defined medium have been...dimethylsulfoxide for the preservation of cat kidney and L cells was 4%. The optimal concentration of dimethylsulfoxide for preservation of HeLa cells was 8...normal growth upon inoculation into growth medium. The viability of Hela cells after one month’s storage was 86% and normal growth resulted upon reinoculation in growth medium.

  17. Updates to the p+p and A+A chemical freeze-out lines from the new experimental data

    CERN Document Server

    Begun, V V; Gorenstein, M I

    2016-01-01

    We show that the new data on mean multiplicities measured in p+p and A+A collisions together with the updated list of resonances lead to the significant changes of the obtained freeze-out lines. The new A+A line gives much smaller temperatures at high collision energies and agrees with the values obtained at the LHC. The newly obtained p+p line is much closer to the A+A line than previously expected, and even touches it in the region where the $K^+/\\pi^+$ horn appears in the data. It indicates that the temperatures that will be obtained in the beam energy and system size scan by the NA61/SHINE Collaboration might be very close. However, our analysis shows that the chemical potentials could be very different for the same energies in A+A and p+p. It adds more puzzles to the set of surprising coincidences at the energies close to the possible onset of deconfinement.

  18. Influence of different sugar cryoprotectants on the stability and physico-chemical characteristics of freeze-dried 5-fluorouracil plurilamellar vesicles

    Directory of Open Access Journals (Sweden)

    Mohamed Mahmoud Nounou

    2005-07-01

    Full Text Available Lyophilization increases the shelf-life of liposomes by preserving it in a dry form as lyophilized cake to be reconstituted with water immediately prior to administration. Aiming at increasing stability and availability of 5-Fluorouracil liposomal products, 5-Fluorouacil Stable Plurilamellar Vesicles were prepared. Freeze dried liposomal dispersions were prepared with or without cryoprotectants. The cryoprotectants used were glucose, mannitol or trehalose in 1, 2 and 4 grams per gram phospholipids. The results showed that lyophilized cake of liposomes without cryoprotectants was compact and difficult to reconstitute, in comparison with fluffy cakes which reconstituted easily and quickly when using cryoprotectants. The percentage of 5-Fluorouracil retained in liposomes freeze-dried without cryoprotectants was 18.29% ± 0.96% and the percentage of 5-Fluorouracil retained in stable plurilamellar vesicles was 31.22% ± 0.62% using 4 grams trehalose as cryoprotectant per gram of lipid. Physico-chemical and release stability studies showed superior potentials of the lyophilized product after reconstitution in comparison to dispersion product. It may be concluded that all tested sugars have cryoprotectant effects that stabilized liposomes in the freeze dried state, where trehalose offered the most superior cryoprotectant effect for freeze dried 5-fluorouracil liposomes.

  19. It is what it eats: Chemically defined media and the history of surrounds.

    Science.gov (United States)

    Landecker, Hannah

    2016-06-01

    The cultivation of living organs, cells, animals, and embryos in the laboratory has been central to the production of biological knowledge. Over the twentieth century, the drive to variance control in the experimental setting led to systematic efforts to generate synthetic, chemically defined substitutes for complex natural foods, housing, and other substrates of life. This article takes up the history of chemically defined media with three aims in mind. First, to characterize patterns of decontextualization, tinkering, and negotiation between life and experimenter that occur across disparate histories of cultivation. Second, to highlight the paradoxical historicity of cultivated organisms generated to be freed from context, as they incorporate and embody the purified amino acids, vitamins, plastics, and other artificial supports developed in the name of experimental control. Third, to highlight the figure-ground reversal that occurs as these cells and organisms are reconsidered as accidentally good models of life in industrialized conditions of pollution and nutrient excess, due to the man-made nature of their surrounds. Methodologically, the history of surrounds is described as an epigenetic approach that focuses on the material relations between different objects and organisms previously considered quite separately, from explanted organs to bacteria to plant cells to rats to human embryos.

  20. Freeze fracture and freeze etching.

    Science.gov (United States)

    Chandler, Douglas E; Sharp, William P

    2014-01-01

    Freeze fracture depends on the property of frozen tissues or cells, when cracked open, to split along the hydrophobic interior of membranes, thus revealing broad panoramas of membrane interior. These large panoramas reveal the three-dimensional contours of membranes making the methods well suited to studying changes in membrane architecture. Freshly split membrane faces are visualized by platinum or tungsten shadowing and carbon backing to form a replica that is then cleaned of tissue and imaged by TEM. Etching, i.e., removal of ice from the frozen fractured specimen by sublimation prior to shadowing, can also reveal the true surfaces of the membrane as well as the extracellular matrix and cytoskeletal networks that contact the membranes. Since the resolution of detail in the metal replicas formed is 1-2 nm, these methods can also be used to visualize macromolecules or macromolecular assemblies either in situ or displayed on a mica surface. These methods are available for either specimens that have been chemically fixed or specimens that have been rapidly frozen without chemical intervention.

  1. Validity of Chemical Equilibrium Approach in the Study of Kinetic Freeze-out in p-Pb Collisions at LHC

    CERN Document Server

    Bashir, Inam-ul; Uddin, Saeed

    2016-01-01

    Transverse momentum spectra of identified pions, Kaons , protons and Lambdas produced at mid-rapidity (0 < ycm < 0.5) in p-Pb collisions at root(sNN) = 5.02 TeV is studied for different collision centralities by using a Unified Statistical Thermal Freeze-out Model (USTFM). A fairly good agreement is seen between the calculated results and the experimental data points taken from the ALICE experiment. Kinetic freeze-out conditions are extracted from the fits of the transverse momentum spectra of these hadrons for each centrality class. A comparison of the obtained freeze-out parameters with those of heavy-ion collisions (Pb + Pb) is made and discussed.

  2. Recombinant human albumin supports single cell cloning of CHO cells in chemically defined media.

    Science.gov (United States)

    Zhu, Jiang; Wooh, Jong Wei; Hou, Jeff Jia Cheng; Hughes, Benjamin S; Gray, Peter P; Munro, Trent P

    2012-01-01

    Biologic drugs, such as monoclonal antibodies, are commonly made using mammalian cells in culture. The cell lines used for manufacturing should ideally be clonal, meaning derived from a single cell, which represents a technically challenging process. Fetal bovine serum is often used to support low cell density cultures, however, from a regulatory perspective, it is preferable to avoid animal-derived components to increase process consistency and reduce the risk of contamination from adventitious agents. Chinese hamster ovary (CHO) cells are the most widely used cell line in industry and a large number of serum-free, protein-free, and fully chemically defined growth media are commercially available, although these media alone do not readily support efficient single cell cloning. In this work, we have developed a simple, fully defined, single-cell cloning media, specifically for CHO cells, using commercially available reagents. Our results show that a 1:1 mixture of CD-CHO™ and DMEM/F12 supplemented with 1.5 g/L of recombinant albumin (Albucult®) supports single cell cloning. This formulation can support recovery of single cells in 43% of cultures compared to 62% in the presence of serum.

  3. Cryopreservation of cynomolgus monkey (Macaca fascicularis) spermatozoa in a chemically defined extender

    Institute of Scientific and Technical Information of China (English)

    Ya-Hui Li; Ke-Jun Cai; Lei Su; Mo Guan; Xie-Chao He; Hong Wang; Andras Kovacs; Wei-Zhi Ji

    2005-01-01

    Aim: To establish a method for cynomolgus monkey sperm cryopreservation in a chemically defined extender.Methods: Semen samples were collected by electro-ejaculation from four sexually mature male cynomolgus monkeys.The spermatozoa were frozen in straws by liquid nitrogen vapor using egg-yolk-free Tes-Tris (mTTE) synthetic extender and glycerol as cryoprotectant. The effects of glycerol concentration (1%, 3%, 5%, 10% and 15% [v/v])and its equilibration time (10 min, 30 min, 60 min and 90 min) on post-thaw spermatozoa were examined by sperm motility and sperm head membrane integrity. Results: The post-thaw motility and head membrane integrity of spermatozoa were significantly higher (P < 0.05) for 5% glycerol (42.95 ± 2.55 and 50.39 ± 2.42, respectively) than those of the other groups (1%: 19.19 ± 3.22 and 24.84 ± 3.64; 3%: 34.23 ± 3.43 and 41.37 ± 3.42; 10%:15.68 ± 2.36 and 21.39 ± 3.14; 15%: 7.47 ± 1.44 and 12.90 ± 2.18). The parameters for 30 min equilibration (42.95 ± 2.55 and 50.39 ± 2.42) were better (P < 0.05) than those of the other groups (10 min: 31.33 ± 3.06 and 38.98 ± 3.31; 60 min: 32.49 ± 3.86 and 40.01 ± 4.18; 90 min: 31.16 ± 3.66 and 38.30 ± 3.78). Five percent glycerol and 30 min equilibration yielded the highest post-thaw sperm motility and head membrane integrity. Conclusion:Cynomolgus monkey spermatozoa can be successfully cryopreserved in a chemically defined extender, which is related to the concentration and the equilibration time of glycerol.

  4. Large-scale production of megakaryocytes from human pluripotent stem cells by chemically defined forward programming

    Science.gov (United States)

    Moreau, Thomas; Evans, Amanda L.; Vasquez, Louella; Tijssen, Marloes R.; Yan, Ying; Trotter, Matthew W.; Howard, Daniel; Colzani, Maria; Arumugam, Meera; Wu, Wing Han; Dalby, Amanda; Lampela, Riina; Bouet, Guenaelle; Hobbs, Catherine M.; Pask, Dean C.; Payne, Holly; Ponomaryov, Tatyana; Brill, Alexander; Soranzo, Nicole; Ouwehand, Willem H.; Pedersen, Roger A.; Ghevaert, Cedric

    2016-01-01

    The production of megakaryocytes (MKs)—the precursors of blood platelets—from human pluripotent stem cells (hPSCs) offers exciting clinical opportunities for transfusion medicine. Here we describe an original approach for the large-scale generation of MKs in chemically defined conditions using a forward programming strategy relying on the concurrent exogenous expression of three transcription factors: GATA1, FLI1 and TAL1. The forward programmed MKs proliferate and differentiate in culture for several months with MK purity over 90% reaching up to 2 × 105 mature MKs per input hPSC. Functional platelets are generated throughout the culture allowing the prospective collection of several transfusion units from as few as 1 million starting hPSCs. The high cell purity and yield achieved by MK forward programming, combined with efficient cryopreservation and good manufacturing practice (GMP)-compatible culture, make this approach eminently suitable to both in vitro production of platelets for transfusion and basic research in MK and platelet biology. PMID:27052461

  5. Physiological study of Lactobacillus delbrueckii subsp. bulgaricus strains in a novel chemically defined medium.

    Science.gov (United States)

    Chervaux, C; Ehrlich, S D; Maguin, E

    2000-12-01

    We developed a chemically defined medium called milieu proche du lait (MPL), in which 22 Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) strains exhibited growth rates ranging from 0.55 to 1 h(-1). MPL can also be used for cultivation of other lactobacilli and Streptococcus thermophilus. The growth characteristics of L. bulgaricus in MPL containing different carbon sources were determined, including an initial characterization of the phosphotransferase system transporters involved. For the 22 tested strains, growth on lactose was faster than on glucose, mannose, and fructose. Lactose concentrations below 0.4% were limiting for growth. We isolated 2-deoxyglucose-resistant mutants from strains CNRZ397 and ATCC 11842. CNRZ397-derived mutants were all deficient for glucose, fructose, and mannose utilization, indicating that these three sugars are probably transported via a unique mannose-specific-enzyme-II-like transporter. In contrast, mutants of ATCC 11842 exhibited diverse phenotypes, suggesting that multiple transporters may exist in that strain. We also developed a protein labeling method and verified that exopolysaccharide production and phage infection can occur in MPL. The MPL medium should thus be useful in conducting physiological studies of L. bulgaricus and other lactic acid bacteria under well controlled nutritional conditions.

  6. Factors affecting exocellular polysaccharide production by Lactobacillus delbrueckii subsp. bulgaricus grown in a chemically defined medium.

    Science.gov (United States)

    Petry, S; Furlan, S; Crepeau, M J; Cerning, J; Desmazeaud, M

    2000-08-01

    We developed a chemically defined medium (CDM) containing lactose or glucose as the carbon source that supports growth and exopolysaccharide (EPS) production of two strains of Lactobacillus delbrueckii subsp. bulgaricus. The factors found to affect EPS production in this medium were oxygen, pH, temperature, and medium constituents, such as orotic acid and the carbon source. EPS production was greatest during the stationary phase. Composition analysis of EPS isolated at different growth phases and produced under different fermentation conditions (varying carbon source or pH) revealed that the component sugars were the same. The EPS from strain L. delbrueckii subsp. bulgaricus CNRZ 1187 contained galactose and glucose, and that of strain L. delbrueckii subsp. bulgaricus CNRZ 416 contained galactose, glucose, and rhamnose. However, the relative proportions of the individual monosaccharides differed, suggesting that repeating unit structures can vary according to specific medium alterations. Under pH-controlled fermentation conditions, L. delbrueckii subsp. bulgaricus strains produced as much EPS in the CDM as in milk. Furthermore, the relative proportions of individual monosaccharides of EPS produced in pH-controlled CDM or in milk were very similar. The CDM we developed may be a useful model and an alternative to milk in studies of EPS production.

  7. Effect of chemical stabilizers on the thermostability and infectivity of a representative panel of freeze dried viruses.

    Directory of Open Access Journals (Sweden)

    Boris Pastorino

    Full Text Available As a partner of the European Virus Archive (EVA FP7 project, our laboratory maintains a large collection of freeze-dried viruses. The distribution of these viruses to academic researchers, public health organizations and industry is one major aim of the EVA consortium. It is known that lyophilization requires appropriate stabilizers to prevent inactivation of the virus. However, few studies have investigated the influence of different stabilizers and lyophilization protocols on the thermostability of different viruses. In order to identify optimal lyophilization conditions that will deliver maximum retention of viral infectivity titre, different stabilizer formulations containing trehalose, sorbitol, sucrose or foetal bovine serum were evaluated for their efficacy in stabilizing a representative panel of freeze dried viruses at different storage temperatures (-20°C, +4°C and +20°C for one week, the two latter mimicking suboptimal shipping conditions. The Tissue Culture Infectious Dose 50% (TCID50 assay was used to compare the titres of infectious virus. The results obtained using four relevant and model viruses (enveloped/non enveloped RNA/DNA viruses still serve to improve the freeze drying conditions needed for the development and the distribution of a large virus collection.

  8. Oxime Catalysis by Freezing.

    Science.gov (United States)

    Agten, Stijn M; Suylen, Dennis P L; Hackeng, Tilman M

    2016-01-20

    Chemical reaction rates are generally decreased at lower temperatures. Here, we report that an oxime ligation reaction in water at neutral pH is accelerated by freezing. The freezing method and its rate effect on oxime ligation are systematically studied on a peptide model system, and applied to a larger chemokine protein, containing a single acetyl butyrate group, which is conjugated to an aminooxy-labeled ligand. Our improved ligation protocol now makes it possible to efficiently introduce oxime-bond coupled ligands into proteins under aqueous conditions at low concentrations and neutral pH.

  9. 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.

  10. Chemical freeze-out in ultra-relativistic heavy ion collisions at sqrt(s)_NN = 130 and 200 GeV

    CERN Document Server

    Manninen, J

    2008-01-01

    A comprehensive and detailed analysis of hadronic abundances measured in Au-Au collisions at RHIC at \\sqrt(s)_NN = 130 and 200 GeV is presented. The rapidity densities measured in the central rapidity region have been fitted to the statistical hadronization model and the chemical freeze-out parameters determined as a function of centrality, using data from experiments BRAHMS, PHENIX and STAR. The chemical freeze-out temperature turns out to be independent of centrality to a few percent accuracy, whereas the strangeness under-saturation parameter $\\gs$ decreases from almost unity in central collisions to a significantly lower value in peripheral collisions. Our results are in essential agreement with previous analyses, with the exception that fit quality at sqrt(s)_NN = 200 GeV is not as good as previously found. From the comparison of the two different energies, we conclude that the difference in fit quality, as described by \\chi^2 values, is owing to the improved resolution of measurements which has probably...

  11. Centrality dependence of chemical freeze-out parameters from net-proton and net-charge fluctuations using hadron resonance gas model

    CERN Document Server

    Adak, Rama Prasad; Ghosh, Sanjay K; Ray, Rajarshi; Samanta, Subhasis

    2016-01-01

    We extract chemical freeze-out parameters in HRG and EVHRG model, analysing the experimental information of net-proton and net-charge fluctuations measured in Au + Au collisions by the STAR collaboration at RHIC. We observe that chemical freeze-out parameters extracted from lower and higher order fluctuations are though almost same for $\\sqrt{s_{NN}} > 27$ GeV, they tend to deviate from each other at lower $\\sqrt{s_{NN}}$. Moreover, these separations increase with decrease of $\\sqrt{s_{NN}}$ and for a fixed $\\sqrt{s_{NN}}$ increase towards central collisions. This may be an indication of approach of critical region at lower $\\sqrt{s_{NN}}$. Furthermore, we observe an approximate scaling behaviour of $(\\mu_B/T)/(\\mu_B/T)_{central}$ with $(N_{part})/(N_{part})_{central}$ for the parameters extracted from lower order fluctuations for 11.5 GeV $\\le \\sqrt{s_{NN}} \\le$ 200 GeV. Scaling is violated for the parameters extracted from higher order fluctuations for $\\sqrt{s_{NN}}= 11.5$ and 19.6 GeV. It is observed that...

  12. Developmental features of rat cerebellar neural cells cultured in a chemically defined medium

    Energy Technology Data Exchange (ETDEWEB)

    Gallo, V.; Ciotti, M.T.; Aloisi, F.; Levi, G.

    1986-01-01

    We studied some aspects of the differentiation of rat cerebellar neural cells obtained from 8-day postnatal animals and cultured in a serum-free, chemically defined medium (CDM). The ability of the cells to take up radioactive transmitter amino acids was analyzed autoradiographically. The L-glutamate analogue /sup 3/H-D-aspartate was taken up by astroglial cells, but not by granule neurons, even in late cultures (20 days in vitro). This is in agreement with the lack of depolarization-induced release of /sup 3/H-D-aspartate previously observed in this type of culture. In contrast, /sup 3/H-(GABA) was scarcely accumulated by glial-fibrillary-acidic-protein (GFAP)-positive astrocytes, but taken up by glutamate-decarboxylase-positive inhibitory interneurons and was released in a Ca2+-dependent way upon depolarization: /sup 3/H-GABA evoked release progressively increased with time in culture. Interestingly, the expression of the vesicle-associated protein synapsin I was much reduced in granule cells cultured in CDM as compared to those maintained in the presence of serum. These data would indicate that in CDM the differentiation of granule neurons is not complete, while that of GABAergic neurons is not greatly affected. Whether the diminished differentiation of granule cells must be attributed only to serum deprivation or also to other differences in the composition of the culture medium remains to be established. /sup 3/H-GABA was avidly taken up also by a population of cells which were not recognized by antibodies raised against GFAP, glutamate decarboxylase, and microtubule-associated protein 2. These cells have been characterized as bipotential precursors of oligodendrocytes and of a subpopulation of astrocytes bearing a stellate shape and capable of high-affinity /sup 3/H-GABA uptake.

  13. Sensory and physico-chemical characteristics of desserts prepared with egg products processed by freeze and spray drying

    Directory of Open Access Journals (Sweden)

    Marcelo Nunes de Jesús

    2013-09-01

    Full Text Available In this work, three freeze-dried (FD egg products (whole egg (WE, egg yolk (EY and egg white (EW were obtained and the acceptability of confections prepared with each was evaluated. Sensory analyses for confections were performed by hedonic testing with fifty panelists in each evaluation. The studied confections were: Condensed Milk Pudding (P, Quindim (Q and Meringue (M. The results obtained for confections made with FD egg products were compared with the achieved through other formulations of the same desserts made with fresh (F or spray-dried (SD egg products. The sensory analysis results for confections made with FD egg products showed good acceptance by panelists. A principal component analysis of the sensory evaluation data was carried out to identify similarities between the different egg products. The PCA supported the conclusion that FD egg products can substitute their fresh and SD counterparts in dessert formulations with good acceptability while keeping the advantages conferred by the freeze-drying method.

  14. Scalable cultivation of human pluripotent stem cells on chemically-defined surfaces

    Science.gov (United States)

    Hsiung, Michael Chi-Wei

    Human stem cells (SCs) are classified as self-renewing cells possessing great ability in therapeutic applications due of their ability to differentiate along any major cell lineage in the human body. Despite their restorative potential, widespread use of SCs is hampered by strenuous control issues. Along with the need for strict xeno-free environments to sustain growth in culture, current methods for growing human pluripotent stem cells (hPSCs) rely on platforms which impede large-scale cultivation and therapeutic delivery. Hence, any progress towards development of large-scale culture systems is severely hindered. In a concentrated effort to develop a scheme that can serve as a model precursor for large scale SC propagation in clinical use, we have explored methods for cultivating hPSCs on completely defined surfaces. We discuss novel approaches with the potential to go beyond the limitations presented by current methods. In particular, we studied the cultivation of human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs) on surface which underwent synthetic or chemical modification. Current methods for hPSCs rely on animal-based extracellular matrices (ECMs) such as mouse embryonic fibroblasts (MEFs) or feeders and murine sacoma cell-derived substrates to facilitate their growth. While these layers or coatings can be used to maximize the output of hPSC production, they cannot be considered for clinical use because they risk introducing foreign pathogens into culture. We have identified and developed conditions for a completely defined xeno-free substrate used for culturing hPSCs. By utilizing coupling chemistry, we can functionalize ester groups on a given surface and conjugate synthetic peptides containing the arginine-glycine-aspartic acid (RGD) motif, known for their role in cell adhesion. This method offers advantages over traditional hPSC culture by keeping the modified substrata free of xenogenic response and can be scaled up in

  15. The effect of chemically defined medium on spontaneous calcium signaling of in situ chondrocytes during long-term culture.

    Science.gov (United States)

    Zhou, Yilu; Park, Miri; Cheung, Enoch; Wang, Liyun; Lu, X Lucas

    2015-04-13

    Chemically defined serum-free medium has been shown to better maintain the mechanical integrity of articular cartilage explants than serum-supplemented medium during long-term in vitro culture, but little is known about its effect on cellular mechanisms. We hypothesized that the chemically defined culture medium could regulate the spontaneous calcium signaling of in situ chondrocytes, which may modulate the cellular metabolic activities. Bovine cartilage explants were cultured in chemically defined serum-free or serum-supplemented medium for four weeks. The spontaneous intracellular calcium ([Ca(2+)]i) signaling of in situ chondrocytes was longitudinally measured together along with the biomechanical properties of the explants. The spontaneous [Ca(2+)]i oscillations in chondrocytes were enhanced at the initial exposure of serum-supplemented medium, but were significantly dampened afterwards. In contrast, cartilage explants in chemically defined medium preserved the level of calcium signaling, and showed more responsive cells with higher and more frequent [Ca(2+)]i peaks throughout the four week culture in comparison to those in serum medium. Regardless of the culture medium that the explants were exposed, a positive correlation was detected between the [Ca(2+)]i responsive rate and the stiffness of cartilage (Spearman's rank correlation coefficient=0.762). A stable pattern of [Ca(2+)]i peaks was revealed for each chondrocyte, i.e., the spatiotemporal features of [Ca(2+)]i peaks from a cell were highly consistent during the observation period (15 min). This study showed that the beneficial effect of chemically defined culture of cartilage explants is associated with the spontaneous [Ca(2+)]i signaling of chondrocytes in cartilage.

  16. Optimization of chemically defined cell culture media--replacing fetal bovine serum in mammalian in vitro methods

    DEFF Research Database (Denmark)

    van der Valk, J; Brunner, D; De Smet, K;

    2010-01-01

    Quality assurance is becoming increasingly important. Good laboratory practice (GLP) and good manufacturing practice (GMP) are now established standards. The biomedical field aims at an increasing reliance on the use of in vitro methods. Cell and tissue culture methods are generally fast, cheap......, reproducible and reduce the use of experimental animals. Good cell culture practice (GCCP) is an attempt to develop a common standard for in vitro methods. The implementation of the use of chemically defined media is part of the GCCP. This will decrease the dependence on animal serum, a supplement...... with an undefined and variable composition. Defined media supplements are commercially available for some cell types. However, information on the formulation by the companies is often limited and such supplements can therefore not be regarded as completely defined. The development of defined media is difficult...

  17. Efficient Construction of Well-Defined Multicompartment Porous Systems in a Modular and Chemically Orthogonal Fashion.

    Science.gov (United States)

    Gao, Ning; Tian, Tian; Cui, Jiecheng; Zhang, Wanlin; Yin, Xianpeng; Wang, Shiqiang; Ji, Jingwei; Li, Guangtao

    2017-03-27

    A microfluidic assembly approach was developed for efficiently producing hydrogel spheres with reactive multidomains that can be employed as an advantageous platform to create spherical porous networks in a facile manner with well-defined multicompartments and spatiotemporally controlled functions. This strategy allows for not only large scale fabrication of various robust hydrogel microspheres with controlled size and porosity, but also the domains embedded in hydrogel network could be introduced in a modular manner. Additionally, the number of different domains and their ratio could be widely variable on demand. More importantly, the reactive groups distributed in individual domains could be used as anchor sites to further incorporate functional units in an orthogonal fashion, leading to well-defined multicompartment systems. The strategy provides a new and efficient route to construct well-defined functional multicompartment systems with great flexibility and extendibility.

  18. Large scale production of megakaryocytes from human pluripotent stem cells by a chemically defined forward programming approach

    OpenAIRE

    Moreau, Thomas; Evans, Amanda L.; Vasquez, Louella; Tijssen, Marloes R.; Yan, Ying; Trotter, Matthew W.; Howard, Daniel; Colzani, Maria; Arumugam, Meera; Wu, Wing Han; Dalby, Amanda; Lampela, Riina; Bouet, Guenaelle; Hobbs, Catherine M.; Dean C Pask

    2016-01-01

    This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Nature Publishing Group. The production of megakaryocytes (MKs) ? the precursors of blood platelets ? from human pluripotent stem cells (hPSCs) offers exciting clinical opportunities for transfusion medicine. We describe an original approach for the large scale generation of MKs in chemically defined conditions using a forward programming strategy relying on the concurrent exogenous e...

  19. Large scale production of megakaryocytes from human pluripotent stem cells by a chemically defined forward programming approach

    OpenAIRE

    Moreau, Thomas; Evans, Amanda L.; Vasquez, Louella; Tijssen, Marloes R.; Yan, Ying; Trotter, Matthew W.; Howard, Daniel; Colzani, Maria; Arumugam, Meera; Wu, Wing Han; Dalby, Amanda; Lampela, Riina; Bouet, Guenaelle; Hobbs, Catherine M.; Dean C Pask

    2016-01-01

    This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Nature Publishing Group. The production of megakaryocytes (MKs) – the precursors of blood platelets – from human pluripotent stem cells (hPSCs) offers exciting clinical opportunities for transfusion medicine. We describe an original approach for the large scale generation of MKs in chemically defined conditions using a forward programming strategy relying on the concurrent exogenous e...

  20. Defining chemical expansion: the choice of units for the stoichiometric expansion coefficient

    DEFF Research Database (Denmark)

    Marrocchelli, Dario; Chatzichristodoulou, Christodoulos; Bishop, Sean R.

    2014-01-01

    Chemical expansion refers to the spatial dilation of a material that occurs upon changes in its composition. When this dilation is caused by a gradual, iso-structural increase in the lattice parameter with composition, it is related to the composition change by the stoichiometric expansion coeffi...... are provided for changes in oxygen content in fluorite, perovskite, and Ruddlesden-Popper (K2NiF4) phase materials used in solid oxide fuel cells....

  1. Chemical Atmosphere-Snow-Sea Ice Interactions: defining future research in the field, lab and modeling

    Science.gov (United States)

    Frey, Markus

    2015-04-01

    The air-snow-sea ice system plays an important role in the global cycling of nitrogen, halogens, trace metals or carbon, including greenhouse gases (e.g. CO2 air-sea flux), and therefore influences also climate. Its impact on atmospheric composition is illustrated for example by dramatic ozone and mercury depletion events which occur within or close to the sea ice zone (SIZ) mostly during polar spring and are catalysed by halogens released from SIZ ice, snow or aerosol. Recent field campaigns in the high Arctic (e.g. BROMEX, OASIS) and Antarctic (Weddell sea cruises) highlight the importance of snow on sea ice as a chemical reservoir and reactor, even during polar night. However, many processes, participating chemical species and their interactions are still poorly understood and/or lack any representation in current models. Furthermore, recent lab studies provide a lot of detail on the chemical environment and processes but need to be integrated much better to improve our understanding of a rapidly changing natural environment. During a 3-day workshop held in Cambridge/UK in October 2013 more than 60 scientists from 15 countries who work on the physics, chemistry or biology of the atmosphere-snow-sea ice system discussed research status and challenges, which need to be addressed in the near future. In this presentation I will give a summary of the main research questions identified during this workshop as well as ways forward to answer them through a community-based interdisciplinary approach.

  2. Effects of B vitamin deletion in chemically defined diets on brood development in Camponotus vicinus (Hymenoptera: Formicidae).

    Science.gov (United States)

    Mankowski, Mark E; Morrell, J J

    2014-08-01

    The potential contributions of B vitamins by a yeast associate to the nutrition of the carpenter ant Camponotus vicinus Mayr was examined as part of an effort to develop a chemically defined diet. This diet was used to test the effects of individual B vitamin and other nutrient deletions on larval development. The chemically defined diet contained amino acids, vitamins, minerals, and other growth factors in a liquid sucrose matrix. C. vicinus worker colonies with third- and fourth-instar larvae were fed a complete artificial diet or that diet with a component deleted for a 12-wk period. There was a significant effect of diet on larval growth and number of adult worker ants produced in the overall nutrient deletion test, but ant development was often better on incomplete diets with one B vitamin deleted compared with the complete holidic basal diet. Thiamine deletion resulted in significantly higher brood weights compared with the complete diet. Diets of sugar water plus all B vitamins, sugar water only, or a diet minus all B vitamins and cholesterol were associated with significantly lower brood weights. Significantly more adult worker ants were produced by worker colonies fed diets minus cholesterol, choline, thiamine, or riboflavin compared with the complete basal diet. The results suggest that the diet, while suitable for rearing, could benefit from further study to better define component levels. The potential relationship of C. vicinus with yeast associates is discussed in relation to further studies.

  3. A Molecular and Chemical Perspective in Defining Melatonin Receptor Subtype Selectivity

    Directory of Open Access Journals (Sweden)

    Yung Hou Wong

    2013-09-01

    Full Text Available Melatonin is primarily synthesized and secreted by the pineal gland during darkness in a normal diurnal cycle. In addition to its intrinsic antioxidant property, the neurohormone has renowned regulatory roles in the control of circadian rhythm and exerts its physiological actions primarily by interacting with the G protein-coupled MT1 and MT2 transmembrane receptors. The two melatonin receptor subtypes display identical ligand binding characteristics and mediate a myriad of signaling pathways, including adenylyl cyclase inhibition, phospholipase C stimulation and the regulation of other effector molecules. Both MT1 and MT2 receptors are widely expressed in the central nervous system as well as many peripheral tissues, but each receptor subtype can be linked to specific functional responses at the target tissue. Given the broad therapeutic implications of melatonin receptors in chronobiology, immunomodulation, endocrine regulation, reproductive functions and cancer development, drug discovery and development programs have been directed at identifying chemical molecules that bind to the two melatonin receptor subtypes. However, all of the melatoninergics in the market act on both subtypes of melatonin receptors without significant selectivity. To facilitate the design and development of novel therapeutic agents, it is necessary to understand the intrinsic differences between MT1 and MT2 that determine ligand binding, functional efficacy, and signaling specificity. This review summarizes our current knowledge in differentiating MT1 and MT2 receptors and their signaling capacities. The use of homology modeling in the mapping of the ligand-binding pocket will be described. Identification of conserved and distinct residues will be tremendously useful in the design of highly selective ligands.

  4. Birth of common marmoset (Callithrix jacchus) offspring derived from in vitro-matured oocytes in chemically defined medium.

    Science.gov (United States)

    Tomioka, I; Takahashi, T; Shimada, A; Yoshioka, K; Sasaki, E

    2012-10-15

    Optimization of oocyte culture conditions is a crucial aspect of reproductive biology and technology. In the present study, maturation of germinal vesicle-stage marmoset oocytes were evaluated in the following media: Waymouth medium, Waymouth medium containing porcine follicular fluid (pFF) (Waymouth-pFF medium), and porcine oocyte medium (POM). Oocytes cultured in Waymouth-pFF medium had higher maturation rates to the metaphase II stage than those cultured in Waymouth medium (36.1% vs. 24.8%, respectively, P marmoset oocytes. Hence, maturation of marmoset oocytes cultured in POM was subsequently evaluated. The rate of maturation to the metaphase I stage was significantly higher and degradation rates were significantly lower in oocytes cultured in POM than those cultured in Waymouth medium. In addition, three offspring were successfully obtained after transfer of embryos matured in chemically defined medium. Therefore, we concluded that POM was suitable for marmoset oocyte culture. Furthermore, this was apparently the first report of marmoset offspring derived from oocytes cultured in chemically defined medium.

  5. A genotype of modified vaccinia Ankara (MVA) that facilitates replication in suspension cultures in chemically defined medium.

    Science.gov (United States)

    Jordan, Ingo; Horn, Deborah; John, Katrin; Sandig, Volker

    2013-01-21

    While vectored vaccines, based on hyperattenuated viruses, may lead to new treatment options against infectious diseases and certain cancers, they are also complex products and sometimes difficult to provide in sufficient amount and purity. To facilitate vaccine programs utilizing host-restricted poxviruses, we established avian suspension cell lines (CR and CR.pIX) and developed a robust, chemically defined, culturing process for production of this class of vectors. For one prominent member, modified vaccinia Ankara (MVA), we now describe a new strain that appears to replicate to greater yields of infectious units, especially in the cell-free supernatant of cultures in chemically defined media. The new strain was obtained by repeated passaging in CR suspension cultures and, consistent with reports on the exceptional genetic stability of MVA, sequencing of 135 kb of the viral genomic DNA revealed that only three structural proteins (A3L, A9L and A34R) each carry a single amino acid exchange (H639Y, K75E and D86Y, respectively). Host restriction in a plaque-purified isolate of the new genotype appears to be maintained in cell culture. Processing towards an injectable vaccine preparation may be simplified with this strain as a complete lysate, containing the main burden of host cell contaminants, may not be required anymore to obtain adequate yields.

  6. Effect of methionine and cysteine deprivation on growth of different natural isolates of Lactobacillus spp. in chemically defined media

    Directory of Open Access Journals (Sweden)

    Lozo Jelena

    2008-01-01

    Full Text Available The purpose of this study was to determine the ability of natural isolates of lactobacilli from different ecological niches to grow in a chemically defined medium in the presence or absence of sulphur-containing amino acids, methionine and/or cysteine. The obtained results indicate that cysteine is essential for growth of L. paracasei subsp. paracasei BGHN14 and BGSJ2-8, while methionine is essential for isolates BGHN40, BGCG31, and BGHV54T of the species L. plantarum. Methionine is also essential for growth of L. rhamnosus BGHV58T. Other analyzed strains, such as L. plantarum BGSJ3-18, BGZB19, BGHV52Ta, and BGHV43T, require the presence of both amino acids for their growth.

  7. Maintenance of Hepatic Functions in Primary Human Hepatocytes Cultured on Xeno-Free and Chemical Defined Human Recombinant Laminins.

    Science.gov (United States)

    Watanabe, Masaaki; Zemack, Helen; Johansson, Helene; Hagbard, Louise; Jorns, Carl; Li, Meng; Ellis, Ewa

    2016-01-01

    Refined methods for maintaining specific functions of isolated hepatocytes under xeno-free and chemical defined conditions is of great importance for the development of hepatocyte research and regenerative therapy. Laminins, a large family of heterotrimeric basement membrane adhesion proteins, are highly cell and tissue type specific components of the extracellular matrix and strongly influence the behavior and function of associated cells and/or tissues. However, detailed biological functions of many laminin isoforms are still to be evaluated. In this study, we determined the distribution of laminin isoforms in human liver tissue and isolated primary human hepatocytes by western blot analysis, and investigated the efficacy of different human recombinant laminin isoforms on hepatic functions during culture. Protein expressions of laminin-chain α2, α3, α4, β1, β3, γ1, and γ2 were detected in both isolated human hepatocytes and liver tissue. No α1 and α5 expression could be detected in liver tissue or hepatocytes. Hepatocytes were isolated from five different individual livers, and cultured on human recombinant laminin isoforms -111, -211, -221, -332, -411, -421, -511, and -521 (Biolamina AB), matrigel (extracted from Engelbreth-Holm-Swarm sarcoma), or collagen type IV (Collagen). Hepatocytes cultured on laminin showed characteristic hexagonal shape in a flat cell monolayer. Viability, double stranded DNA concentration, and Ki67 expression for hepatocytes cultured for six days on laminin were comparable to those cultured on EHS and Collagen. Hepatocytes cultured on laminin also displayed production of human albumin, alpha-1-antitrypsin, bile acids, and gene expression of liver-enriched factors, such as hepatocyte nuclear factor 4 alpha, glucose-6-phosphate, cytochrome P450 3A4, and multidrug resistance-associated protein 2. We conclude that all forms of human recombinant laminin tested maintain cell viability and liver-specific functions of primary human

  8. Freezing and Food Safety

    Science.gov (United States)

    ... and Food Safety What Can You Freeze? Is Frozen Food Safe? Does Freezing Destroy Bacteria & Parasites? Freshness & Quality ... Temperatures Freezer Storage Time Safe Thawing Refreezing Cooking Frozen Foods Power Outage in Freezer Frozen Cans Frozen Eggs ...

  9. A chemically defined culture medium containing Rho kinase inhibitor Y-27632 for the fabrication of stratified squamous epithelial cell grafts

    Energy Technology Data Exchange (ETDEWEB)

    Aslanova, Afag [Department of Surgery, Institute of Gastroenterology, Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Institute of Advanced Biomedical Engineering and Science, Tokyo Women' s Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Takagi, Ryo; Yamato, Masayuki; Okano, Teruo [Institute of Advanced Biomedical Engineering and Science, Tokyo Women' s Medical University, TWIns, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan); Yamamoto, Masakazu, E-mail: yamamoto.ige@twmu.ac.jp [Department of Surgery, Institute of Gastroenterology, Tokyo Women' s Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666 (Japan)

    2015-05-01

    With the development of a culture method for stratified squamous epithelial cells, tissue-engineered epithelial cell sheets have been successfully applied as clinical cell grafts. However, the implementation of these cell sheets without the use of any animal-derived materials is highly desirable. In this study, Rho-associated protein kinase inhibitor Y-27632 was used to develop a chemically defined culture medium for the fabrication of stratified epithelial cell grafts consisting of human epidermal and oral keratinocytes, and the proliferation activity, cell morphology, and gene expressions of the keratinocytes were analyzed. The results of a colorimetric assay indicated that Y-27632 significantly promoted the proliferation of the keratinocytes in culture media both with and without fetal bovine serum (FBS), although there were no indications of Y-27632 efficacy on cell morphology and stratification of the keratinocytes in culture medium without any animal-derived materials. The results of quantitative RT-PCR revealed that gene expressions correlated with cell adhesion, cell–cell junction, proliferation markers, and stem/progenitor markers in cultured keratinocytes were not strongly affected by the addition of Y-27632 to the culture medium. Moreover, gene expressions of differentiation markers in stratified keratinocytes cultured in medium without FBS were nearly identical to those of keratinocytes co-cultured with 3T3 feeder cells. Interestingly, the expressions of differentiation markers in cultured stratified keratinocytes were suppressed by FBS, whereas they were reconstructed by either co-culture of a 3T3 feeder layer or addition of Y-27632 into the culture medium containing FBS. These findings indicate that Y-27632 is a useful supplement for the development of a chemically defined culture medium for fabrication of stratified epithelial cell grafts for clinical applications for the purpose of developing the culture medium with a lower risk of pathogen

  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. Chinese hamster ovary cell performance enhanced by a rational divide-and-conquer strategy for chemically defined medium development.

    Science.gov (United States)

    Liu, Yaya; Zhang, Weiyan; Deng, Xiancun; Poon, Hong Fai; Liu, Xuping; Tan, Wen-Song; Zhou, Yan; Fan, Li

    2015-12-01

    Basal medium design is considered one of the most important steps in process development. To optimize chemically defined (CD) media efficiently and effectively for the biopharmaceutical industry, a two-step rational strategy was applied to optimize four antibody producing Chinese hamster ovary (CHO) cell lines. In the first step, 48 of 52 components of our in-house medium were divided into three groups according to their characteristics. In the next step, these groups were optimized by spent medium analysis, response surface methodology and mixture design. Because these steps in our strategy involved dividing medium components into groups and subsequently adjusting the concentration of the components, we termed this medium development strategy "divide and conquer". By applying the strategy, we were able to improve the titers of CHO-S, CHO-DG44 and two CHO-K1 cell lines 1.92, 1.86, 2.92 and 1.62-fold, respectively, in 8 weeks with fewer than 60 tests. This divide-and-conquer strategy was efficient, effective, scalable and universal in our current study and offered a new approach to CD media development.

  12. Studies on a chemically defined medium for in vitro culture of in vitro matured and fertilized porcine oocytes.

    Science.gov (United States)

    Iwasaki, T; Kimura, E; Totsukawa, K

    1999-03-01

    The present study evaluated the effects of various components in a chemically defined medium on the development of IVM/IVF porcine embryos. The investigated components included energy substrates (lactate, pyruvate or glucose, alone or in various combinations), amino acids (glutamine, glycine or alanine), PVP and HEPES buffer. The effects of each energy substrate were the same as the control. However, a mixture of lactate with either of the other energy substrates increased the development rate. Glutamine tended to decrease rate of the development more than other amino acids, and this inhibition was dose dependent. Both PVP and HEPES buffer did not affect development rate. However, more than 35 mM HEPES buffer induced fragmentation From the above results, a new culture medium was designed (supplemented with 0.276 mM glycine, 0.176 mM alanine, 15 mM HEPES buffer and 1% (wt/vol) PVP in BSA-free Whitten's medium with or without glucose). The new medium resulted in a higher embryo development rate (20.4 and 16.3%) than that obtained with the control medium (10.0%).

  13. Norepinephrine stimulates progesterone production in highly estrogenic bovine granulosa cells cultured under serum-free, chemically defined conditions

    Directory of Open Access Journals (Sweden)

    Piccinato Carla A

    2012-11-01

    Full Text Available Abstract Background Since noradrenergic innervation was described in the ovarian follicle, the actions of the intraovarian catecholaminergic system have been the focus of a variety of studies. We aimed to determine the gonadotropin-independent effects of the catecholamine norepinephrine (NE in the steroid hormone profile of a serum-free granulosa cell (GC culture system in the context of follicular development and dominance. Methods Primary bovine GCs were cultivated in a serum-free, chemically defined culture system supplemented with 0.1% polyvinyl alcohol. The culture features were assessed by hormone measurements and ultrastructural characteristics of GCs. Results GCs produced increasing amounts of estradiol and pregnenolone for 144h and maintained ultrastructural features of healthy steroidogenic cells. Progesterone production was also detected, although it significantly increased only after 96h of culture. There was a highly significant positive correlation between estradiol and pregnenolone production in high E2-producing cultures. The effects of NE were further evaluated in a dose–response study. The highest tested concentration of NE (10 (−7 M resulted in a significant increase in progesterone production, but not in estradiol or pregnenolone production. The specificity of NE effects on progesterone productio n was further investigated by incubating GCs with propranolol (10 (−8 M, a non-selective beta-adrenergic antagonist. Conclusions The present culture system represents a robust model to study the impact of intrafollicular factors, such as catecholamines, in ovarian steroidogenesis and follicular development. The results of noradrenergic effects in the steroidogenesis of GC have implications on physiological follicular fate and on certain pathological ovarian conditions such as cyst formation and anovulation.

  14. 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.

  15. An improved high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry method for determination of chlorophylls and their derivatives in freeze-dried and hot-air-dried Rhinacanthus nasutus (L.) Kurz.

    Science.gov (United States)

    Kao, Tsai Hua; Chen, Chia Ju; Chen, Bing Huei

    2011-10-30

    Rhinacanthus nasutus (L.) Kurz, a traditional Chinese herb possessing antioxidant and anti-cancer activities, has been reported to contain functional components like carotenoids and chlorophylls. However, the variety and amount of chlorophylls remain uncertain. The objectives of this study were to develop a high performance liquid chromatography-photodiode array detection-atmospheric pressure chemical ionization-mass spectrometry (HPLC-DAD-APCI-MS) method for determination of chlorophylls and their derivatives in hot-air-dried and freeze-dried R. nasutus. An Agilent Eclipse XDB-C18 column and a gradient mobile phase composed of methanol/N,N-dimethylformamide (97:3, v/v), acetonitrile and acetone were employed to separate internal standard zinc-phthalocyanine plus 12 cholorophylls and their derivatives within 21 min, including chlorophyll a, chlorophyll a', hydroxychlorophyll a, 15-OH-lactone chlorophyll a, chlorophyll b, chlorophyll b', hydroxychlorophyll b, pheophytin a, pheophytin a', hydroxypheophytin a, hydroxypheophytin a' and pheophytin b in hot-air-dried R. nasutus with flow rate at 1 mL/min and detection at 660 nm. But, in freeze-dried R. nasutus, only 4 chlorophylls and their derivatives, including chlorophyll a, chlorophyll a', chlorophyll b and pheophytin a were detected. Zinc-phthalocyanine was found to be an appropriate internal standard to quantify all the chlorophyll compounds. After quantification by HPLC-DAD, both chlorophyll a and pheophytin a were the most abundant in hot-air-dried R. nasutus, while in freeze-dried R. nasutus, chlorophyll a and chlorophyll b dominated.

  16. Efeito do congelamento nas características físicas e químicas do pão de queijo Effect of freezing on the physical and chemical characteristics of cheese bread

    Directory of Open Access Journals (Sweden)

    Rossana Pierangeli Godinho Silva

    2009-02-01

    Full Text Available A qualidade do pão de queijo está diretamente ligada à matéria-prima utilizada, a preparação da massa, ao congelamento e ao assamento, sendo que falhas nestes processos podem resultar em um produto de baixa aceitação no mercado, tanto nacional quanto internacional. O presente trabalho foi desenvolvido no Departamento de Ciência dos Alimentos da Universidade Federal de Lavras, Minas Gerais e objetivou acompanhar as características físico-químicas da massa e do pão de queijo, durante um período de 120 dias de congelamento. Observou-se para a massa modelada de pão de queijo um menor valor de umidade na massa fresca; os teores de cinzas, extrato etéreo e pH decresceram com o congelamento; já o conteúdo de acidez titulável aumentou durante o período. Com relação aos pães de queijo, verificou-se que os valores de umidade e cinzas não apresentaram variação durante o período; o teor de pH apresentou variações durante todo o congelamento, com menores valores ao final de 120 dias; o conteúdo lipídico apresentou decréscimo em todo o período e a acidez titulável decresceu até próximo aos 60 dias, com posterior aumento até o final do congelamento. O armazenamento congelado também levou a um aumento na força de compressão, ou seja, a uma maior firmeza dos pães de queijo.The quality of cheese bread is directly linked to the raw material used, the preparation of the dough, freezing, and baking. Fail in these processes may result in a product of low acceptance in the national and international market. The present research was carried out at the Food Science Department of the Universidade Federal de Lavras, Minas Gerais with the aim to accompany the physical and chemical characteristics of the dough and cheese bread, during a period of 120 days of freezing. The modeled dough of cheese bread presented lower moisture content value in the fresh dough; the ash content, ethereal extract and pH decreased with freezing however

  17. Automated assessment of Pavlovian conditioned freezing and shock reactivity in mice using the VideoFreeze system

    Directory of Open Access Journals (Sweden)

    Stephan G Anagnostaras

    2010-09-01

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

  18. Separation of Scaptotrigona postica workers into defined task groups by the chemical profile on their epicuticle wax layer.

    Science.gov (United States)

    Poiani, Silvana B; Morgan, E David; Drijfhout, Falko P; da Cruz-Landim, Carminda

    2014-04-01

    During evolution, the cuticle surface of insects acquired functions in communication, such as inter- and intra-specific recognition, identification of gender, physiological state, and fertility. In eusocial bees, the information in the cuticular surface is important not only to discriminate nestmates from non-nestmates but also to identify an individual's class, life phase or task. A comparative study of the cuticular surface chemical profile of workers of Scaptotrigona postica in different phases of life, i.e., newly emerged workers (NE), brood comb area workers (CA), and forager workers (FO) was undertaken by gas chromatography linked to mass spectrometry. Multivariate statistical analysis was performed to verify how workers are grouped according to their chemical profile and to determine which compounds are responsible for separating them into groups. The cuticle surface of workers contains mainly hydrocarbons and a small amount of oxygenated compounds. Multivariate statistical analysis showed qualitative and quantitative variation in relation to the life phases/tasks performed, and all groups were distinct. The most abundant compound found in NE and CA was n-heptacosane, while in FO, it was (Z)-9-heptacosene. The compounds that differentiate NE from other groups are n-tricosane and n-hexacosane. A (Z)-X-octacosene and n-nonacosane are the chemicals that distinguish CA from NE and FO, while 11- and 13-methylpentacosane, (Z)-X-hexacosene, and (Z)-9-heptacosene characterize FO as distinct from NE and CA. The probable function of alkenes is nestmate recognition, mainly in FO. The results show that the cuticle surfaces of workers are characteristic of the phase of life/task performed by workers, allowing intra-colonial recognition.

  19. The use of biodiversity as source of new chemical entities against defined molecular targets for treatment of malaria, tuberculosis, and T-cell mediated diseases--a review.

    Science.gov (United States)

    Basso, Luiz Augusto; da Silva, Luiz Hildebrando Pereira; Fett-Neto, Arthur Germano; de Azevedo, Walter Filgueira; Moreira, Icaro de Souza; Palma, Mário Sérgio; Calixto, João Batista; Astolfi Filho, Spartaco; dos Santos, Ricardo Ribeiro; Soares, Milena Botelho Pereira; Santos, Diógenes Santiago

    2005-10-01

    The modern approach to the development of new chemical entities against complex diseases, especially the neglected endemic diseases such as tuberculosis and malaria, is based on the use of defined molecular targets. Among the advantages, this approach allows (i) the search and identification of lead compounds with defined molecular mechanisms against a defined target (e.g. enzymes from defined pathways), (ii) the analysis of a great number of compounds with a favorable cost/benefit ratio, (iii) the development even in the initial stages of compounds with selective toxicity (the fundamental principle of chemotherapy), (iv) the evaluation of plant extracts as well as of pure substances. The current use of such technology, unfortunately, is concentrated in developed countries, especially in the big pharma. This fact contributes in a significant way to hamper the development of innovative new compounds to treat neglected diseases. The large biodiversity within the territory of Brazil puts the country in a strategic position to develop the rational and sustained exploration of new metabolites of therapeutic value. The extension of the country covers a wide range of climates, soil types, and altitudes, providing a unique set of selective pressures for the adaptation of plant life in these scenarios. Chemical diversity is also driven by these forces, in an attempt to best fit the plant communities to the particular abiotic stresses, fauna, and microbes that co-exist with them. Certain areas of vegetation (Amazonian Forest, Atlantic Forest, Araucaria Forest, Cerrado-Brazilian Savanna, and Caatinga) are rich in species and types of environments to be used to search for natural compounds active against tuberculosis, malaria, and chronic-degenerative diseases. The present review describes some strategies to search for natural compounds, whose choice can be based on ethnobotanical and chemotaxonomical studies, and screen for their ability to bind to immobilized drug targets

  20. The use of biodiversity as source of new chemical entities against defined molecular targets for treatment of malaria, tuberculosis, and T-cell mediated diseases: a review

    Directory of Open Access Journals (Sweden)

    Luiz Augusto Basso

    2005-10-01

    Full Text Available The modern approach to the development of new chemical entities against complex diseases, especially the neglected endemic diseases such as tuberculosis and malaria, is based on the use of defined molecular targets. Among the advantages, this approach allows (i the search and identification of lead compounds with defined molecular mechanisms against a defined target (e.g. enzymes from defined pathways, (ii the analysis of a great number of compounds with a favorable cost/benefit ratio, (iii the development even in the initial stages of compounds with selective toxicity (the fundamental principle of chemotherapy, (iv the evaluation of plant extracts as well as of pure substances. The current use of such technology, unfortunately, is concentrated in developed countries, especially in the big pharma. This fact contributes in a significant way to hamper the development of innovative new compounds to treat neglected diseases. The large biodiversity within the territory of Brazil puts the country in a strategic position to develop the rational and sustained exploration of new metabolites of therapeutic value. The extension of the country covers a wide range of climates, soil types, and altitudes, providing a unique set of selective pressures for the adaptation of plant life in these scenarios. Chemical diversity is also driven by these forces, in an attempt to best fit the plant communities to the particular abiotic stresses, fauna, and microbes that co-exist with them. Certain areas of vegetation (Amazonian Forest, Atlantic Forest, Araucaria Forest, Cerrado-Brazilian Savanna, and Caatinga are rich in species and types of environments to be used to search for natural compounds active against tuberculosis, malaria, and chronic-degenerative diseases. The present review describes some strategies to search for natural compounds, whose choice can be based on ethnobotanical and chemotaxonomical studies, and screen for their ability to bind to immobilized

  1. Culture of bovine ovarian follicle wall sections maintained the highly estrogenic profile under basal and chemically defined conditions

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, R.B. [Laboratório de Biotecnologia da Reprodução, Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil); Salles, L.P. [Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil); Silva, I. Oliveira e; Gulart, L.V.M. [Laboratório de Biotecnologia da Reprodução, Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil); Souza, D.K. [Laboratório de Biotecnologia da Reprodução, Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil); Faculdade de Ceilândia, Universidade de Brasília, Ceilândia, DF (Brazil); Torres, F.A.G. [Laboratório de Biologia Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil); Bocca, A.L. [Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil); Silva, A.A.M. Rosa e [Laboratório de Biotecnologia da Reprodução, Departamento de Ciências Fisiológicas, Instituto de Ciências Biológicas, Universidade de Brasília, Brasília, DF (Brazil)

    2013-08-16

    Follicle cultures reproduce in vitro the functional features observed in vivo. In a search for an ideal model, we cultured bovine antral follicle wall sections (FWS) in a serum-free defined medium (DM) known to induce 17β-estradiol (E{sub 2}) production, and in a nondefined medium (NDM) containing serum. Follicles were sectioned and cultured in NDM or DM for 24 or 48 h. Morphological features were determined by light microscopy. Gene expression of steroidogenic enzymes and follicle-stimulating hormone (FSH) receptor were determined by RT-PCR; progesterone (P{sub 4}) and E{sub 2} concentrations in the media were measured by radioimmunoassay. DM, but not NDM, maintained an FWS morphology in vitro that was similar to fresh tissue. DM also induced an increase in the expression of all steroidogenic enzymes, except FSH receptor, but NDM did not. In both DM and NDM, there was a gradual increase in P{sub 4} throughout the culture period; however, P{sub 4} concentration was significantly higher in NDM. In both media, E{sub 2} concentration was increased at 24 h, followed by a decrease at 48 h. The E{sub 2}:P{sub 4} ratio was higher in DM than in NDM. These results suggest that DM maintains morphological structure, upregulates the expression of steroidogenic enzyme genes, and maintains steroid production with a high E{sub 2}:P{sub 4} ratio in FWS cultures.

  2. Differential effects of defined chemical modifications on antigenic and pharmacological activities of scorpion alpha and beta toxins.

    Science.gov (United States)

    el Ayeb, M; Darbon, H; Bahraoui, E M; Vargas, O; Rochat, H

    1986-03-03

    Specific chemical modifications of scorpion alpha and beta toxins have been used to study the involvement of particular residues in both the pharmacological and the antigenic sites of these toxins. Modification by 1,2-cyclohexanedione of arginine-27 of a beta toxin, Centruroides suffusus suffusus toxin II, drastically decrease the antigenic activity without any influence on the pharmacological activity. Conversely, modification by the same reagent of arginine-2 of an alpha toxin, Androctonus australis Hector toxin III, led to a 100-times less pharmacologically potent derivative and did not induce a significant loss of antigenic activity. Excision of the N-terminal pentapeptide of another alpha toxin, Buthus occitanus mardochei toxin III, by pepsin digestion led to a non-toxic derivative retaining full antigenic activity. Thus, the N-terminal part of the conserved hydrophobic surface of the toxin is highly implicated in the pharmacological activity, whereas the region of arginine-27, located in the alpha helix situated on the back surface, opposite the conserved hydrophobic region, is fully implicated in the antigenic activity and is far from the pharmacological site. These results are good arguments in favor of the idea that in scorpion toxins the surfaces implicated in the pharmacological and the antigenic activities do not overlap. Since the antigenic sites are present in highly variable sequence the development of an efficient polyvalent serotherapy is questionable.

  3. Use of multiple chemical tracers to define habitat use of Indo-Pacific mangrove crab, Scylla serrata (Decapoda: Portunidae)

    Science.gov (United States)

    Demopoulos, A.W.J.; Cormier, N.; Ewel, K.C.; Fry, B.

    2008-01-01

    The mangrove or mud crab, Scylla serrata, is an important component of mangrove fisheries throughout the Indo-Pacific. Understanding crab diets and habitat use should assist in managing these fisheries and could provide additional justification for conservation of the mangrove ecosystem itself. We used multiple chemical tracers to test whether crab movements were restricted to local mangrove forests, or extended to include adjacent seagrass beds and reef flats. We sampled three mangrove forests on the island of Kosrae in the Federated States of Micronesia at Lelu Harbor, Okat River, and Utwe tidal channel. Samples of S. serrata and likely food sources were analyzed for stable carbon (??13C), nitrogen (??15N), and sulfur (??34S) isotopes. Scylla serrata tissues also were analyzed for phosphorus (P), cations (K, Ca, Mg, Na), and trace elements (Mn, Fe, Cu, Zn, and B). Discriminant analysis indicated that at least 87% of the crabs remain in each site as distinct populations. Crab stable isotope values indicated potential differences in habitat use within estuaries. Values for ??13C and ??34S in crabs from Okat and Utwe were low and similar to values expected from animals feeding within mangrove forests, e.g., feeding on infauna that had average ??13C values near -26.5???. In contrast, crabs from Lelu had higher ?? 13C and ??34S values, with average values of -21.8 and 7.8???, respectively. These higher isotope values are consistent with increased crab foraging on reef flats and seagrasses. Given that S. serrata have been observed feeding on adjacent reef and seagrass environments on Kosrae, it is likely that they move in and out of the mangroves for feeding. Isotope mixing model results support these conclusions, with the greatest mangrove ecosystem contribution to S. serrata diet occurring in the largest mangrove forests. Conserving larger island mangrove forests (> 1 km deep) appears to support crab foraging activities. ?? 2007 Coastal and Estuarine Research

  4. Bjorken model with Freeze Out

    CERN Document Server

    Magas, V K

    2007-01-01

    The freeze out of the expanding systems, created in relativistic heavy ion collisions, is discussed. We combine Bjorken scenario with earlier developed freeze out equations into a unified model. The important feature of the proposed model is that physical freeze out is completely finished in a finite time, which can be varied from 0 (freeze out hypersurface) to infinity. The dependence of the post freeze out distribution function on this freeze out time will be studied. As an example model is completely solved and analyzed for the gas of pions.

  5. Monolayer culturing and cloning of human pluripotent stem cells on laminin-521-based matrices under xeno-free and chemically defined conditions.

    Science.gov (United States)

    Rodin, Sergey; Antonsson, Liselotte; Hovatta, Outi; Tryggvason, Karl

    2014-10-01

    A robust method for culturing human pluripotent stem (hPS) cells under chemically defined and xeno-free conditions is an important tool for stem cell research and for the development of regenerative medicine. Here, we describe a protocol for monolayer culturing of Oct-4-positive hPS cells on a specific laminin-521 (LN-521) isoform, under xeno-free and chemically defined conditions. The cells are dispersed into single-cell suspension and then plated on LN-521 isoform at densities higher than 5,000 cells per cm², where they attach, migrate and survive by forming small monolayer cell groups. The cells avidly divide and expand horizontally until the entire dish is covered by a confluent monolayer. LN-521, in combination with E-cadherin, allows cloning of individual hPS cells in separate wells of 96-well plates without the presence of rho-associated protein kinase (ROCK) inhibitors or any other inhibitors of anoikis. Characterization of cells maintained for several months in culture reveals pluripotency with a minimal degree of genetic abnormalities.

  6. 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.

  7. Non-integrating episomal plasmid-based reprogramming of human amniotic fluid stem cells into induced pluripotent stem cells in chemically defined conditions.

    Science.gov (United States)

    Slamecka, Jaroslav; Salimova, Lilia; McClellan, Steven; van Kelle, Mathieu; Kehl, Debora; Laurini, Javier; Cinelli, Paolo; Owen, Laurie; Hoerstrup, Simon P; Weber, Benedikt

    2016-01-01

    Amniotic fluid stem cells (AFSC) represent an attractive potential cell source for fetal and pediatric cell-based therapies. However, upgrading them to pluripotency confers refractoriness toward senescence, higher proliferation rate and unlimited differentiation potential. AFSC were observed to rapidly and efficiently reacquire pluripotency which together with their easy recovery makes them an attractive cell source for reprogramming. The reprogramming process as well as the resulting iPSC epigenome could potentially benefit from the unspecialized nature of AFSC. iPSC derived from AFSC also have potential in disease modeling, such as Down syndrome or β-thalassemia. Previous experiments involving AFSC reprogramming have largely relied on integrative vector transgene delivery and undefined serum-containing, feeder-dependent culture. Here, we describe non-integrative oriP/EBNA-1 episomal plasmid-based reprogramming of AFSC into iPSC and culture in fully chemically defined xeno-free conditions represented by vitronectin coating and E8 medium, a system that we found uniquely suited for this purpose. The derived AF-iPSC lines uniformly expressed a set of pluripotency markers Oct3/4, Nanog, Sox2, SSEA-1, SSEA-4, TRA-1-60, TRA-1-81 in a pattern typical for human primed PSC. Additionally, the cells formed teratomas, and were deemed pluripotent by PluriTest, a global expression microarray-based in-silico pluripotency assay. However, we found that the PluriTest scores were borderline, indicating a unique pluripotent signature in the defined condition. In the light of potential future clinical translation of iPSC technology, non-integrating reprogramming and chemically defined culture are more acceptable.

  8. Understanding freeze stress in biological tissues: Thermodynamics of interfacial water

    Energy Technology Data Exchange (ETDEWEB)

    Olien, C. Robert [USDA-ARS (retired), Crop and Soil Sciences, Michigan State University, East Lansing, MI 48824-1325 (United States); Livingston, David P. [USDA and North Carolina State University, Crop Science, 840 Method Road, Unit 3, Raleigh, NC 27502 (United States)]. E-mail: dpl@unity.ncsu.edu

    2006-12-01

    A thermodynamic approach to distinguish forms of freeze energy that injure plants as the temperature decreases is developed. The pattern resulting from this analysis dictated the sequence of thermal requirements for water to exist as an independent state. Improvement of freezing tolerance in biological systems depends on identification of a specific form of stress, just as control of a disease depends on identification of the pathogen causing the disease. The forms of energy that stress hydrated systems as temperature decreases begin with disruption of biological function from chill injury that occurs above freezing. Initiation of non-equilibrium freezing with sufficient free energy to drive disruptive effects can occur in a supercooled system. As the temperature continues to decrease and freezing occurs in an equilibrium manner, adhesion at hydrated interfaces contributes to disruptive effects as protoplasts contract by freeze-dehydration. If protective systems are able to prevent injury from direct interactions with ice, passive effects of freeze-dehydration may cause injury at lower temperatures. The temperature range in which an injury occurs is an indicator of the form of energy causing stress. The form of energy is thus a primary guide for selection of a protective mechanism. An interatomic force model whose response to temperature change corresponds with the enthalpy pattern might help define freeze stress from a unique perspective.

  9. Measurement of Antibiotic Consumption: A Practical Guide to the Use of the Anatomical Therapeutic Chemical Classification and Defined Daily Dose System Methodology in Canada

    Directory of Open Access Journals (Sweden)

    James M Hutchinson

    2004-01-01

    Full Text Available Despite the global public health importance of resistance of microorganisms to the effects of antibiotics, and the direct relationship of consumption to resistance, little information is available concerning levels of consumption in Canadian hospitals and out-patient settings. The present paper provides practical advice on the use of administrative pharmacy data to address this need. Focus is made on the use of the Anatomical Therapeutic Chemical classification and Defined Daily Dose system. Examples of consumption data from Canadian community and hospital settings, with comparisons to international data, are used to incite interest and to propose uses of this information. It is hoped that all persons responsible for policy decisions regarding licensing, reimbursement, prescribing guidelines, formulary controls or any other structure pertaining to antimicrobial use become conversant with the concepts of population antibiotic consumption and that this paper provides them with the impetus and direction to begin accurately measuring and comparing antibiotic use in their jurisdictions.

  10. Chemically defined diet alters the protective properties of fructo-oligosaccharides and isomalto-oligosaccharides in HLA-B27 transgenic rats.

    Directory of Open Access Journals (Sweden)

    Petya Koleva

    Full Text Available Non-digestible oligosaccharides (NDO were shown to reduce inflammation in experimental colitis, but it remains unclear whether microbiota changes mediate their colitis-modulating effects. This study assessed intestinal microbiota and intestinal inflammation after feeding chemically defined AIN-76A or rat chow diets, with or without supplementation with 8 g/kg body weight of fructo-oligosaccharides (FOS or isomalto-oligosaccharides (IMO. The study used HLA-B27 transgenic rats, a validated model of inflammatory bowel disease (IBD, in a factorial design with 6 treatment groups. Intestinal inflammation and intestinal microbiota were analysed after 12 weeks of treatment. FOS and IMO reduced colitis in animals fed rat chow, but exhibited no anti-inflammatory effect when added to AIN-76A diets. Both NDO induced specific but divergent microbiota changes. Bifidobacteria and Enterobacteriaceae were stimulated by FOS, whereas copy numbers of Clostridium cluster IV were decreased. In addition, higher concentrations of total short-chain fatty acids (SCFA were observed in cecal contents of rats on rat chow compared to the chemically defined diet. AIN-76A increased the relative proportions of propionate, iso-butyrate, valerate and iso-valerate irrespective of the oligosaccharide treatment. The SCFA composition, particularly the relative concentration of iso-butyrate, valerate and iso-valerate, was associated (P ≤ 0.004 and r ≥ 0.4 with increased colitis and IL-1 β concentration of the cecal mucosa. This study demonstrated that the protective effects of fibres on colitis development depend on the diet. Although diets modified specific cecal microbiota, our study indicates that these changes were not associated with colitis reduction. Intestinal inflammation was positively correlated to protein fermentation and negatively correlated with carbohydrate fermentation in the large intestine.

  11. Chemically defined diet alters the protective properties of fructo-oligosaccharides and isomalto-oligosaccharides in HLA-B27 transgenic rats.

    Science.gov (United States)

    Koleva, Petya; Ketabi, Ali; Valcheva, Rosica; Gänzle, Michael G; Dieleman, Levinus A

    2014-01-01

    Non-digestible oligosaccharides (NDO) were shown to reduce inflammation in experimental colitis, but it remains unclear whether microbiota changes mediate their colitis-modulating effects. This study assessed intestinal microbiota and intestinal inflammation after feeding chemically defined AIN-76A or rat chow diets, with or without supplementation with 8 g/kg body weight of fructo-oligosaccharides (FOS) or isomalto-oligosaccharides (IMO). The study used HLA-B27 transgenic rats, a validated model of inflammatory bowel disease (IBD), in a factorial design with 6 treatment groups. Intestinal inflammation and intestinal microbiota were analysed after 12 weeks of treatment. FOS and IMO reduced colitis in animals fed rat chow, but exhibited no anti-inflammatory effect when added to AIN-76A diets. Both NDO induced specific but divergent microbiota changes. Bifidobacteria and Enterobacteriaceae were stimulated by FOS, whereas copy numbers of Clostridium cluster IV were decreased. In addition, higher concentrations of total short-chain fatty acids (SCFA) were observed in cecal contents of rats on rat chow compared to the chemically defined diet. AIN-76A increased the relative proportions of propionate, iso-butyrate, valerate and iso-valerate irrespective of the oligosaccharide treatment. The SCFA composition, particularly the relative concentration of iso-butyrate, valerate and iso-valerate, was associated (P ≤ 0.004 and r ≥ 0.4) with increased colitis and IL-1 β concentration of the cecal mucosa. This study demonstrated that the protective effects of fibres on colitis development depend on the diet. Although diets modified specific cecal microbiota, our study indicates that these changes were not associated with colitis reduction. Intestinal inflammation was positively correlated to protein fermentation and negatively correlated with carbohydrate fermentation in the large intestine.

  12. Freezing increment in keratophakia.

    Science.gov (United States)

    Swinger, C A; Wisnicki, H J

    In homoplastic keratomileusis, keratophakia, and epikeratophakia, the corneal tissue that provides the final refractive lenticule undergoes a conformational change when frozen. Because corneal tissue is composed primarily of water, an assumed value of 9.08% (approximate volumic percentage expansion of water when frozen) is frequently used for the increase in thickness, or freezing increment, rather than measuring it directly. We evaluated 32 cases of clinical keratophakia and found the increase in thickness to average 37 +/- 21%. In this series of 32 cases, the percentage of patients with a greater than 4 D residual refractive error was 16%. If an assumed freezing increment of 9.08% had been used, the percentage would have been 28%, with two-thirds of these 28% manifesting a marked undercorrection. Because of a lack of studies documenting the behavior of corneal tissue following cryoprotection and freezing, it is suggested that measurements be taken during homoplastic surgery to minimize the potential for significant inaccuracy in obtaining the desired optic result.

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

    Science.gov (United States)

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

    2012-09-01

    The objective of the present work was to determine whether hydrolysis in a model lyophile was influenced by general media effects with water-changing properties of the medium or via a specific mechanism of water as a reactant. Four formulations of zoniporide and sucrose (1:10) were prepared with variable amounts of sorbitol [0%-25% (w/v) of total solids). These formulations were then equilibrated at 6% and 11% relative humidity using saturated salt solutions. The lyophile cakes were analyzed by differential scanning calorimetery (DSC), (isothermal microcalorimetry (IMC), solid- state nuclear magnetic resonance (ssNMR) spectroscopy, and ultraviolet-visible diffuse reflectance (DFR) spectroscopy. DSC and IMC were used to assess the global molecular mobility. ssNMR relaxation times were measured to access local mobility. The DFR was used to determine the solid-state acidity expressed as the Hammett acidity function. Stability of samples was evaluated at 40°C by monitoring potency and purity by high-performance liquid chromatography (HPLC). Results were interpreted in terms of the various roles of water: media effect, plasticization, polarity, and reactant. The kinetics of hydrolysis was observed to be correlated with either/both specific "chemical" effects, that is, water reactant as well as media effect, specifically global molecular mobility of the matrix. Increase in reaction rate with increase in water content is not linear and is a weaker dependence than in some hydrolytic reactions in organic solvents. A moderate amount of an inert plasticizer, sorbitol, conferred additional stabilization, possibly by restricting the amplitude and frequency of fast motions that are on a small length scale.

  14. Winter railcar unloading: heat thawing vs FCA. [Freeze conditioning agents

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, R.J.

    1983-11-01

    The use of freeze conditioning agents and thawing by radiant heat are compared as methods for freezing coal for unloading from railcars in severe weather. The costs of the methods are evaluated and it is shown that, although heating systems require capital expenditure, if a sufficient volume of coal is to be treated, the cost per ton compares very favourably with the use of chemical agents.

  15. Importance of freeze-thaw events in low temperature ecotoxicology of cold tolerant enchytraeids.

    Science.gov (United States)

    Silva, Ana L Patrício; Enggrob, Kirsten; Slotsbo, Stine; Amorim, Mónica J B; Holmstrup, Martin

    2014-08-19

    Due to global warming it is predicted that freeze-thaw cycles will increase in Arctic and cold temperate regions. The effects of this variation becomes of particular ecological importance to freeze-tolerant species when it is combined with chemical pollutants. We compared the effect of control temperature (2 °C), daily freeze-thaw cycles (2 to -4 °C) and constant freezing (-2 °C) temperatures on the cold-tolerance of oligochaete worms (Enchytraeus albidus) and tested how survival was influenced by pre-exposure to 4-nonylphenol (4-NP), a common nonionic detergent found in sewage sludge amended soils. Results showed that combined effect of 4-NP and daily freeze-thaw cycles can cause higher mortality to worms as compared with sustained freezing or control temperature. Exposure to 4-NP caused a substantial depletion of glycogen reserves which is catabolized during freezing to produce cryoprotective concentrations of free glucose. Further, exposure to freeze-thaw cycles resulted in higher concentrations of 4-NP in worm tissues as compared to constant freezing or control temperature (2 °C). Thus, worms exposed to combined effect of freeze-thaw cycles and 4-NP suffer higher consequences, with the toxic effect of the chemical potentiating the deleterious effects of freezing and thawing.

  16. Classification and Assessment of Freeze-Thaw Erosion in Tibet, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-guo; YANG Yong-hong; LIU Shu-zhen

    2005-01-01

    Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze-thaw erosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of the lower bound of the freeze-thaw erosion zones of Qinghai-Tibet Plateau was been established in this paper. Moreover, the freeze-thaw erosion zones in Tibet was been identified by using Geographical Information System (GIS) software. Next, based on the comprehensive analysis of impact factors of freeze-thaw erosion, this paper chooses annul temperature range, slop and vegetation as three indexes, works out the criteria for relative classification of freeze-thaw erosion, and realizes the relative classification of the freeze-thaw erosion in Tibet under the support of GIS software. Then, a synthetic assessment of freeze-thaw erosion in Tibet was been done according to the relative classification result.

  17. Biomaterials by freeze casting.

    Science.gov (United States)

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

    2010-04-28

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

  18. 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.

  19. Characterization of the Pivotal Carbon Metabolism of Streptococcus suis Serotype 2 under ex Vivo and Chemically Defined in Vitro Conditions by Isotopologue Profiling*

    Science.gov (United States)

    Willenborg, Jörg; Huber, Claudia; Koczula, Anna; Lange, Birgit; Eisenreich, Wolfgang; Valentin-Weigand, Peter; Goethe, Ralph

    2015-01-01

    Streptococcus suis is a neglected zoonotic pathogen that has to adapt to the nutritional requirements in the different host niches encountered during infection and establishment of invasive diseases. To dissect the central metabolic activity of S. suis under different conditions of nutrient availability, we performed labeling experiments starting from [13C]glucose specimens and analyzed the resulting isotopologue patterns in amino acids of S. suis grown under in vitro and ex vivo conditions. In combination with classical growth experiments, we found that S. suis is auxotrophic for Arg, Gln/Glu, His, Leu, and Trp in chemically defined medium. De novo biosynthesis was shown for Ala, Asp, Ser, and Thr at high rates and for Gly, Lys, Phe, Tyr, and Val at moderate or low rates, respectively. Glucose degradation occurred mainly by glycolysis and to a minor extent by the pentose phosphate pathway. Furthermore, the exclusive formation of oxaloacetate by phosphoenolpyruvate (PEP) carboxylation became evident from the patterns in de novo synthesized amino acids. Labeling experiments with S. suis grown ex vivo in blood or cerebrospinal fluid reflected the metabolic adaptation to these host niches with different nutrient availability; however, similar key metabolic activities were identified under these conditions. This points at the robustness of the core metabolic pathways in S. suis during the infection process. The crucial role of PEP carboxylation for growth of S. suis in the host was supported by experiments with a PEP carboxylase-deficient mutant strain in blood and cerebrospinal fluid. PMID:25575595

  20. Characterization of the pivotal carbon metabolism of Streptococcus suis serotype 2 under ex vivo and chemically defined in vitro conditions by isotopologue profiling.

    Science.gov (United States)

    Willenborg, Jörg; Huber, Claudia; Koczula, Anna; Lange, Birgit; Eisenreich, Wolfgang; Valentin-Weigand, Peter; Goethe, Ralph

    2015-02-27

    Streptococcus suis is a neglected zoonotic pathogen that has to adapt to the nutritional requirements in the different host niches encountered during infection and establishment of invasive diseases. To dissect the central metabolic activity of S. suis under different conditions of nutrient availability, we performed labeling experiments starting from [(13)C]glucose specimens and analyzed the resulting isotopologue patterns in amino acids of S. suis grown under in vitro and ex vivo conditions. In combination with classical growth experiments, we found that S. suis is auxotrophic for Arg, Gln/Glu, His, Leu, and Trp in chemically defined medium. De novo biosynthesis was shown for Ala, Asp, Ser, and Thr at high rates and for Gly, Lys, Phe, Tyr, and Val at moderate or low rates, respectively. Glucose degradation occurred mainly by glycolysis and to a minor extent by the pentose phosphate pathway. Furthermore, the exclusive formation of oxaloacetate by phosphoenolpyruvate (PEP) carboxylation became evident from the patterns in de novo synthesized amino acids. Labeling experiments with S. suis grown ex vivo in blood or cerebrospinal fluid reflected the metabolic adaptation to these host niches with different nutrient availability; however, similar key metabolic activities were identified under these conditions. This points at the robustness of the core metabolic pathways in S. suis during the infection process. The crucial role of PEP carboxylation for growth of S. suis in the host was supported by experiments with a PEP carboxylase-deficient mutant strain in blood and cerebrospinal fluid.

  1. Cod and rainbow trout as freeze-chilled meal elements

    DEFF Research Database (Denmark)

    Jensen, Louise Helene Søgaard; Nielsen, Jette; Jørgensen, Bo

    2010-01-01

    Meal elements' are elements of a meal, e.g. portions of pre-fried meat, sauces, frozen fish or pre-processed vegetables typically prepared industrially. The meal elements are distributed to professional satellite kitchens, where the staff can combine them into complete meals. Freeze...... and cod and rainbow trout seem potential candidates for freeze-chilled meal elements. (C) 2009 Society of Chemical Industry......-chilling is a process consisting of freezing and frozen storage followed by thawing and chilled storage. Combining the two would enable the manufacturer to produce large quantities of frozen meal elements to be released into the chill chain according to demand. We have studied the influence of freeze...

  2. Define Project

    DEFF Research Database (Denmark)

    Munk-Madsen, Andreas

    2005-01-01

    "Project" is a key concept in IS management. The word is frequently used in textbooks and standards. Yet we seldom find a precise definition of the concept. This paper discusses how to define the concept of a project. The proposed definition covers both heavily formalized projects and informally...... organized, agile projects. Based on the proposed definition popular existing definitions are discussed....

  3. 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.

  4. Conscious worst case definition for risk assessment, part I: a knowledge mapping approach for defining most critical risk factors in integrative risk management of chemicals and nanomaterials.

    Science.gov (United States)

    Sørensen, Peter B; Thomsen, Marianne; Assmuth, Timo; Grieger, Khara D; Baun, Anders

    2010-08-15

    This paper helps bridge the gap between scientists and other stakeholders in the areas of human and environmental risk management of chemicals and engineered nanomaterials. This connection is needed due to the evolution of stakeholder awareness and scientific progress related to human and environmental health which involves complex methodological demands on risk management. At the same time, the available scientific knowledge is also becoming more scattered across multiple scientific disciplines. Hence, the understanding of potentially risky situations is increasingly multifaceted, which again challenges risk assessors in terms of giving the 'right' relative priority to the multitude of contributing risk factors. A critical issue is therefore to develop procedures that can identify and evaluate worst case risk conditions which may be input to risk level predictions. Therefore, this paper suggests a conceptual modelling procedure that is able to define appropriate worst case conditions in complex risk management. The result of the analysis is an assembly of system models, denoted the Worst Case Definition (WCD) model, to set up and evaluate the conditions of multi-dimensional risk identification and risk quantification. The model can help optimize risk assessment planning by initial screening level analyses and guiding quantitative assessment in relation to knowledge needs for better decision support concerning environmental and human health protection or risk reduction. The WCD model facilitates the evaluation of fundamental uncertainty using knowledge mapping principles and techniques in a way that can improve a complete uncertainty analysis. Ultimately, the WCD is applicable for describing risk contributing factors in relation to many different types of risk management problems since it transparently and effectively handles assumptions and definitions and allows the integration of different forms of knowledge, thereby supporting the inclusion of multifaceted risk

  5. Ca, Sr, O and D isotope approach to defining the chemical evolution of hydrothermal fluids: Example from Long Valley, CA, USA

    Science.gov (United States)

    Brown, Shaun T.; Kennedy, B. Mack; DePaolo, Donald J.; Hurwitz, Shaul; Evans, William C.

    2013-12-01

    We present chemical and isotopic data for fluids, minerals and rocks from the Long Valley meteoric-hydrothermal system. The samples encompass the presumed hydrothermal upwelling zone in the west moat of the caldera, the Casa Diablo geothermal field, and a series of wells defining a nearly linear, ∼16 km long, west-to-east trend along the likely fluid flow path. Fluid samples were analyzed for the isotopes of water, Sr, and Ca, the concentrations of major cations and anions, alkalinity, and total CO2. Water isotope data conform to trends documented in earlier studies, interpreted as indicating a single hydrothermal fluid mixing with local groundwater. Sr isotopes show subtle changes along the flow path, which requires rapid fluid flow and minimal reaction between the channelized fluids and the wallrocks. Sr and O isotopes are used to calculate fracture spacing using a dual porosity model. Calculated fracture spacing and temperature data for hydrothermal fluids indicate the system is (approximately) at steady-state. Correlated variations among total CO2, and the concentration and isotopic composition of Ca suggest progressive fluid degassing (loss of CO2), which drives calcite precipitation as the fluid flows west-to-east and cools. The shifts in Ca isotopes require that calcite precipitated at temperatures of 150-180 °C is fractionated by ca. -0.3‰ to -0.5‰ relative to aqueous species. Our data are the first evidence that Ca isotopes undergo kinetic fractionation at high temperatures (>100 °C) and can be used to trace calcite precipitation along hydrothermal fluid flow paths.

  6. A chemically defined 2,3-trans procyanidin fraction from willow bark causes redox-sensitive endothelium-dependent relaxation in porcine coronary arteries.

    Science.gov (United States)

    Kaufeld, Aurica M; Pertz, Heinz H; Kolodziej, Herbert

    2014-07-25

    Extracts of the bark of willow species (Salix spp.) are popular herbal remedies to relieve fever and inflammation. The effects are attributed to salicin and structurally related phenolic metabolites, while polyphenols including procyanidins are suggested to contribute to the overall effect of willow bark. This study aimed at investigating the relaxant response to a highly purified and chemically defined 2,3-trans procyanidin fraction in porcine coronary arteries. The procyanidin sample produced a concentration-dependent relaxation in U46619-precontracted tissues. Relaxation was predominantly mediated through the redox-sensitive activation of the endothelial phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway, leading to the subsequent activation of endothelial nitric oxide synthase (eNOS) by phosphorylation, as evidenced by Western blotting using human umbilical vein endothelial cells (HUVECs). That the relaxant response to Salix procyanidins was reactive oxygen species (ROS)-dependent with O2(-) as the key species followed from densitometric analysis using 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA assay) and employment of various ROS inhibitors, respectively. The data also suggested the modification of intracellular Ca(2+) levels and KCa channel functions. In addition, our organ bath studies showed that Salix procyanidins reversed the abrogation of the relaxant response to bradykinin by oxidized low-density lipoproteins (oxLDL) in coronary arteries, suggesting a vasoprotective effect of willow bark against detrimental oxLDL in pathological conditions. Taken together, our findings suggest for the first time that 2,3-trans procyanidins may contribute not only to the beneficial effects of willow bark but also to health-promoting benefits of diverse natural products of plant origin.

  7. Differences in the glycosylation profile of a monoclonal antibody produced by hybridomas cultured in serum-supplemented, serum-free or chemically defined media.

    Science.gov (United States)

    Serrato, J Antonio; Hernández, Vanessa; Estrada-Mondaca, Sandino; Palomares, Laura A; Ramírez, Octavio T

    2007-06-01

    SFM (serum-free medium) is preferred to media containing animal-derived components when culturing mammalian cells for the production of therapeutic recombinant proteins and mAbs (monoclonal antibodies). Nonetheless, eliminating animal-derived components from media can strongly modify culture performance and alter protein glycosylation. In the present study, mAb glycosylation profiles, extracellular exoglycosidase activities, hybridoma growth and mAb production in traditional medium containing 10% (v/v) FBS (fetal bovine serum) [DMEM (Dulbecco's modified Eagle's medium)/FBS] were compared with those obtained in either SFM or CDM (chemically defined medium). SFM and CDM supported higher cell and mAb concentrations than did DMEM/FBS; however, CE (capillary electrophoresis) analyses revealed important changes in mAb glycosylation patterns. Glycosylation patterns showed a broad microheterogeneity in all the media, ranging from complex to high-mannose and paucimannosidic glycans. mAb produced in DMEM/FBS presented 26 glycan structures, whereas a lower glycan microheterogeneity was found for cultures in CDM or SFM, which presented 24 and 22 structures respectively. In DMEM/FBS and CDM, complex glycans without terminal galactose (G0) represented 28 and 32% of the total glycans respectively and 42 and 46% corresponded to galactosylated structures (G1 plus G2) respectively. In contrast, G0 glycans in SFM accounted for 58%, whereas only 28% corresponded to G1 and G2 structures. Extracellular beta-galactosidase activity increased approx. 3-fold in SFM, which can explain the higher G0 content compared with cultures in the other two media. A desirable decrease in sialylated structures, but an undesirable increase in fucosylated forms, was observed in mAb produced in SFM and CDM media. Approxi. 80% of potential mAb glycosylation sites were occupied, regardless of the culture medium used.

  8. Freezing of charged colloids in slit pores.

    Science.gov (United States)

    Grandner, Stefan; Klapp, Sabine H L

    2008-12-28

    Using Monte Carlo simulations in the grand canonical and isobaric ensembles we investigate freezing phenomena in a charged colloidal suspension confined to narrow slit pores. Our model involves only the macroions which interact via a Derjaguin-Landau-Verwey-Overbeek (DLVO) potential supplemented by a soft-sphere potential. We focus on DLVO parameters typical for moderately charged silica particles (with charges Z approximately 35) in solvents of low ionic strengths. The corresponding DLVO interactions are too weak to drive a (bulk) freezing transition. Nevertheless, for sufficiently small surface separations L(z) the confined systems display not only layering but also significant in-plane crystalline order at chemical potentials where the bulk system is a globally stable fluid (capillary freezing). At confinement conditions related to two-layer systems the observed in-plane structures are consistent with those detected in ground state calculations for perfect Yukawa bilayers [R. Messina and H. Lowen, Phys. Rev. Lett. 91, 146101 (2003)]. Here we additionally observe (at fixed L(z)) a compression-induced first-order phase transition from a two-layer to a three-layer system with different in-plane structure, in agreement with previous findings for pure hard spheres.

  9. RESEARCH OF MOISTURE MIGRATION DURING PARTIAL FREEZING OF GROUND BEEF

    Directory of Open Access Journals (Sweden)

    V. M. Stefanovskiy

    2016-01-01

    Full Text Available The concept of «ideal product» is proposed for the study of mass transfer during partial freezing of food products by freezing plate. The ideal product is a product, in which number of factors affecting the «real product» (meat are excluded. These factors include chemical composition of meat, quality grade of raw material (NOR, DFD, PSE, cryoscopic temperature that determines the degree of water transformation into ice, the phenomenon of osmosis, rate of freezing, etc. By using the concept of «ideal product» and its implementation in a physical experiment, it is proved that the “piston effect” causing the migration of moisture is due to frozen crust formation during partial freezing of the body. During partial freezing of the product by freezing plate, «ideal» and «real» food environment is transformed from closed system into open one with inflow of moisture to unfrozen part of the body. In the «ideal product», there is an expulsion of unfrozen moisture from freezing front, so the water appears on the body surface. Thus, the displacement of moisture increases by the same law, according to which the thickness (weight of frozen layer increases. During partial freezing of ground meat, moisture does not appear on the surface of the product, but hydrates the unfrozen part of meat. The reason of this phenomenon is the expulsion of water during formation of frozen crust and water-binding capacity of meat.

  10. 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...... 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...... 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...

  11. 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..., and Facility Requirements § 590.534 Freezing facilities. (a) Freezing rooms, either on or off the... as set forth in § 590.536. Use of off-premise freezing facilities is permitted only when...

  12. 冷冻-解冻循环对鲤鱼肉物理化学特性的影响%Effect of Number of Freeze-thaw Cycles on Physico-chemical Characteristics of Carp Muscle

    Institute of Scientific and Technical Information of China (English)

    郭园园; 孔保华; 夏秀芳; 杨振

    2011-01-01

    研究不同冷冻-解冻循环次数(0、1、3、5次)对鲤鱼脊背肉pH值、失水率、蒸煮损失、剪切力、肌肉颜色、硫代巴比妥酸值(TBARS)、羰基含量和电泳图谱的影响,从而确定冻融次数对鱼肉物理化学特性的影响。结果表明:随着冷冻-解冻循环次数的增加,鱼肉pH值呈现出先上升后下降的趋势;失水率和蒸煮损失不断增加,到第5次循环时分别增加了8.77%和20.28%,且差异显著(P〈0.05);剪切力经1次冷冻-解冻循环后降低56.3%,随后缓慢下降;TBARS值、羰基含量L*和b*值不断增加,而a*值逐渐降低;鱼肉肌原纤%The pH,water loss rate,cook loss,shear force,color parameters,thiobarbituric acid reactive substances(TBARS),carnonyl content and sodium dodecyl sulphate polyacrylamide gel electrophoresis(SDS-PAGE) pattern of carp back muscles were measured after different freeze-thaw cycles(0,1,3 and 5) with the aim of determining the effect of number of freeze-thaw cycles on the physicochemical characteristics of carp muscle.Results indicated that pH value showed a trend to first increase and then decrease as the number of freeze-thaw cycle increased.Water loss rate and cooking loss exhibited an upward trend and were increased by 8.77% and 20.28%,respectively,after the fifth freeze-thaw cycle(P0.05).Shearing force was decreased by 56.3% after one freeze-thaw cycle(P0.05),followed by a slow decline.Five freeze-thaw cycles could significantly increase TBARS,carnonyl content,L*value and b*value,and decrease a* values(P0.05).All myofibrillar protein bands in the SDS-PAGE pattern got lighter in color and even disappeared with increasing number of freeze-thaw cycles,indicating protein degradation and denaturation.Good correlations were found between lipid oxidation and either protein oxidation or color change.In summary,repeated freeze-thaw could cause protein denaturation and has a detrimental effect on the quality

  13. Dynamics and Sizes of the Fireball at Freeze-out

    CERN Document Server

    Tomasik, Boris; Heinz, Ulrich W; Tomasik, Boris; Wiedemann, Urs Achim; Heinz, Ulrich

    2000-01-01

    Analyzing the m_t-spectrum and two-particle correlations of negative hadrons from 158 AGeV/c Pb+Pb collisions at slightly forward rapidities we find a (thermal) freeze-out temperature of about 100 MeV and transverse flow with approximately 0.55c. The M_t-dependence of the correlation radii prefers a box-like transverse density profile over a Gaussian. From an analysis of the pion phase-space density we find pion chemical potential of approximately 60 MeV at thermal freeze-out.

  14. Freezing in a vertical tube

    Energy Technology Data Exchange (ETDEWEB)

    Sparrow, E.M.; Broadbent, J.A.

    1983-05-01

    Fundamental heat transfer experiments were performed for freezing of an initially superheated or nonsuperheated liquid in a cooled vertical tube. Measurements were made which yielded information about the freezing front and the frozen mass, about the various energy components extracted from the tube, and about the decay of the initial liquid superheat. Four component energies were identified and evaluated from the experimental data, including the latent energy released by the phase change and sensibly energies released from the subcooled frozen solid and the superheated liquid. Initial superheating of the liquid tended to moderately diminish the frozen mass and latent energy extraction at short freezing times but had little effect on these quantitites at longer times. The extracted sensible energies associated with the superheating more than compensated for the aforementioned decrease in the latent energy. Although the latent energy is the largest contributor to the total extracted energy, the aggregate sensible energies can make a significant contribution, especially at large tube wall subcooling, large initial liquid superheating, and short freezing time. Natural convection effects in the superheated liquid were modest and were confined to short freezing times.

  15. Quantitative and qualitative shifts in defensive metabolites define chemical defense investment during leaf development in Inga, a genus of tropical trees.

    Science.gov (United States)

    Wiggins, Natasha L; Forrister, Dale L; Endara, María-José; Coley, Phyllis D; Kursar, Thomas A

    2016-01-01

    Selective pressures imposed by herbivores are often positively correlated with investments that plants make in defense. Research based on the framework of an evolutionary arms race has improved our understanding of why the amount and types of defenses differ between plant species. However, plant species are exposed to different selective pressures during the life of a leaf, such that expanding leaves suffer more damage from herbivores and pathogens than mature leaves. We hypothesize that this differential selective pressure may result in contrasting quantitative and qualitative defense investment in plants exposed to natural selective pressures in the field. To characterize shifts in chemical defenses, we chose six species of Inga, a speciose Neotropical tree genus. Focal species represent diverse chemical, morphological, and developmental defense traits and were collected from a single site in the Amazonian rainforest. Chemical defenses were measured gravimetrically and by characterizing the metabolome of expanding and mature leaves. Quantitative investment in phenolics plus saponins, the major classes of chemical defenses identified in Inga, was greater for expanding than mature leaves (46% and 24% of dry weight, respectively). This supports the theory that, because expanding leaves are under greater selective pressure from herbivores, they rely more upon chemical defense as an antiherbivore strategy than do mature leaves. Qualitatively, mature and expanding leaves were distinct and mature leaves contained more total and unique metabolites. Intraspecific variation was greater for mature leaves than expanding leaves, suggesting that leaf development is canalized. This study provides a snapshot of chemical defense investment in a speciose genus of tropical trees during the short, few-week period of leaf development. Exploring the metabolome through quantitative and qualitative profiling enables a more comprehensive examination of foliar chemical defense investment.

  16. 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.

  17. 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....

  18. 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.

  19. Facing Freeze: Social Threat Induces Bodily Freeze in Humans

    NARCIS (Netherlands)

    Roelofs, K.; Hagenaars, M.A.; Stins, J.F.

    2010-01-01

    Freezing is a common defensive response in animals threatened by predators. It is characterized by reduced body motion and decreased heart rate (bradycardia). However, despite the relevance of animal defense models in human stress research, studies have not shown whether social threat cues elicit si

  20. Medical and social egg freezing

    DEFF Research Database (Denmark)

    Lallemant, Camille; Vassard, Ditte; Andersen, Anders Nyboe

    2016-01-01

    was collected from September 2012 to September 2013 and the responses of 973 women were analyzed. In total, 83% of women reported having heard of egg freezing, and nearly all considered it acceptable for medical indications, whilst 89% considered it acceptable for social reasons. Overall, 19% expressed active...

  1. 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.

  2. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  3. 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.

  4. 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...

  5. Indication of Differential Kinetic Freeze-out at RHIC and LHC Energies

    CERN Document Server

    Thakur, D; Garg, P; and, R Sahoo; Cleymans, J

    2016-01-01

    The transverse momentum spectra at RHIC and LHC for A+A and p+p collisions are studied with Tsallis distributions in different approaches i.e. with and without radial flow. The information on the freeze-out surface in terms of freeze-out volume, temperature, chemical potential and radial flow velocities for different particle species are obtained. These parameters are found to show a systematic behavior with mass dependence. It is observed that the heavier particles freeze-out early as compared to lighter particles and freeze-out surfaces are different for different particles, which is a direct signature of mass dependent differential freeze-out. Further, we observe that the radial flow velocity decreases with increasing mass. This confirms the mass ordering behavior in collectivity observed in heavy-ion collisions. It is also observed that the systems created in peripheral heavy-ion collisions and in proton-proton collisions are of similar thermodynamic nature.

  6. Conscious worst case definition for risk assessment, part I. A knowledge mapping approach for defining most critical risk factors in integrative risk management of chemicals and nanomaterials

    DEFF Research Database (Denmark)

    Sørensen, P.S.; Thomsen, M.; Assmuth, T.

    2010-01-01

    and environmental health which involves complex methodological demands on risk management. At the same time, the available scientific knowledge is also becoming more scattered across multiple scientific disciplines. Hence, the understanding of potentially risky situations is increasingly multifaceted, which again...... a conceptual modelling procedure that is able to define appropriate worst case conditions in complex risk management. The result of the analysis is an assembly of system models, denoted the Worst Case Definition (WCD) model, to set up and evaluate the conditions of multi-dimensional risk identification...... and effectively handles assumptions and definitions and allows the integration of different forms of knowledge, thereby supporting the inclusion of multifaceted risk components in cumulative risk management....

  7. 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)

  8. Generation of eye field/optic vesicle-like structures from human embryonic stem cells under two-dimensional and chemically defined conditions.

    Science.gov (United States)

    Parvini, Maryam; Parivar, Kazem; Safari, Fatemeh; Tondar, Mahdi

    2015-03-01

    Despite the enormous progress in studying retinal cell differentiation from human embryonic stem cells (hESCs), none of the reported protocols have produced a cost-effective eye field cells with the capability to further differentiate into retinal derivatives. In this study, by drawing chemicals on our four-step differentiation strategy, we demonstrated the ability of hESCs in assembling such qualifications to follow human retinogenesis in a serum- and feeder-free adherent condition. Two-dimensional (2D) populations of eye field cells arose within early forebrain progeny upon hESCs differentiation. Gene expression analysis showed that the treatment of hESCs with a combination of selected small molecules (SMs) gave rise to the higher expressions of eye field-specific genes, PAX6, RX, and SIX3. Thereafter, a subset of cells gained the transient features of advancing retinal differentiation, including optic vesicle (OV)-like structures, which expressed MITF and CHX10 in a manner imitated in vivo human retinal development. The competency of derived cells in differentiation to retinal derivatives was further investigated. The gene analysis of the cells showed more propensity for generating retinal pigment epithelial (RPE) than neural retina (NR). The generation of OV-like structures in 2D cultures can shed light on molecular events governing retinal specification. It can also facilitate the study of human retinal development.

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

    Science.gov (United States)

    Cutbirth, J. Michael

    2012-01-01

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

  10. Properties of subvisible cirrus clouds formed by homogeneous freezing

    Directory of Open Access Journals (Sweden)

    B. Kärcher

    2002-04-01

    Full Text Available Number concentrations and mean sizes of ice crystals and derived microphysical and optical properties of subvisible cirrus clouds (SVCs formed by homogeneous freezing of supercooled aerosols are investigated as a function of temperature and updraft speed of adiabatically ascending air parcels. The properties of such clouds are insensitive to variations of the aerosol number and size distribution. Based on criteria constraining the optical extinction, sedimentation time, and existence time of SVCs, longer-lived (>10 min clouds, capable of exerting a measurable radiative or chemical impact, are generated within a narrow range of updraft speeds below 1 - 2 cm s -1 at temperatures below about 215K, with concentrations of ice crystals not exceeding 0.1 cm-3. The clouds do not reach an equilibrium state because the ice crystals sediment out of the formation layer typically before the supersaturation is removed. Given these results, it seems likely that a limited number (<0.1 cm-3 of effective heterogeneous freezing nuclei that nucleate ice below the homogeneous freezing threshold can control the formation and properties of SVCs, although homogeneous freezing nuclei are far more abundant.

  11. Effect of particle surface area on ice active site densities retrieved from droplet freezing spectra

    Science.gov (United States)

    Beydoun, Hassan; Polen, Michael; Sullivan, Ryan C.

    2016-10-01

    Heterogeneous ice nucleation remains one of the outstanding problems in cloud physics and atmospheric science. Experimental challenges in properly simulating particle-induced freezing processes under atmospherically relevant conditions have largely contributed to the absence of a well-established parameterization of immersion freezing properties. Here, we formulate an ice active, surface-site-based stochastic model of heterogeneous freezing with the unique feature of invoking a continuum assumption on the ice nucleating activity (contact angle) of an aerosol particle's surface that requires no assumptions about the size or number of active sites. The result is a particle-specific property g that defines a distribution of local ice nucleation rates. Upon integration, this yields a full freezing probability function for an ice nucleating particle. Current cold plate droplet freezing measurements provide a valuable and inexpensive resource for studying the freezing properties of many atmospheric aerosol systems. We apply our g framework to explain the observed dependence of the freezing temperature of droplets in a cold plate on the concentration of the particle species investigated. Normalizing to the total particle mass or surface area present to derive the commonly used ice nuclei active surface (INAS) density (ns) often cannot account for the effects of particle concentration, yet concentration is typically varied to span a wider measurable freezing temperature range. A method based on determining what is denoted an ice nucleating species' specific critical surface area is presented and explains the concentration dependence as a result of increasing the variability in ice nucleating active sites between droplets. By applying this method to experimental droplet freezing data from four different systems, we demonstrate its ability to interpret immersion freezing temperature spectra of droplets containing variable particle concentrations. It is shown that general

  12. 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.

  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. 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.

  15. Freezing and thawing of processed meat in an industrial freezing tunnel

    Directory of Open Access Journals (Sweden)

    Glaucio Antonio Marini

    2014-04-01

    Full Text Available Freezing is a commonly used preservation method in the meat industry. The understanding of the product behavior during the freezing process can assist in a better process management and quality control. This work reports the study of freezing and thawing of three types of processed meat in order to determine process parameters in an industrial forced‑air freezing tunnel at ‑30oC. Chicken sausages (frankfurter type, mortadela (bologna type and mechanically deboned chicken meat (MDCM were studied. Products were placed in several layers in corrugated cardboard boxes (CCB for sausages and mortadela. MDCM was placed in a nylon box. Temperature sensors were inserted in the products and the freezing and thawing curves were obtained. Freezing curves were used to determine the freezing time (tf, initial freezing point (Tf and final freezing point (T’m. Products placed in different layers in the CCB had significantly different freezing times, being the higher rates for products placed in more external layers than internal ones. The external layers of product were subjected to heat transfer by convection showing its importance to decrease freezing time. The results strongly suggest that products placed in different layers could have distinct quality properties and also play a key role in the freezing process efficiency.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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...

  2. Monitoring the freezing point of buffalo milk

    Directory of Open Access Journals (Sweden)

    Antonella Pesce

    2016-05-01

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

  3. 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%.

  4. 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)

  5. Freeze-Thaw Resistance of Normal and High Strength Concretes Produced with Fly Ash and Silica Fume

    Directory of Open Access Journals (Sweden)

    Cenk Karakurt

    2015-01-01

    Full Text Available This study is based on determination of the freeze-thaw resistance of air-entrained and non-air-entrained normal strength concrete (NC and high strength concrete (HSC produced with fly ash and silica fume according to surface scaling. The procedure allows us to measure the amount of scaling per unit surface area due to a number of well defined freezing and thawing cycles in the presence of deicing salt. The weight loss, surface scaling, moisture uptake, and internal damage were measured after 0 and after every 4th freeze-thaw cycle. The test results showed that the freeze-thaw resistance is influenced directly by the compressive strength property of the concrete. Silica fume significantly reduced the resistance of normal strength concrete against freeze-thaw effect without plasticizing agent. The surface scaling of silica fume concrete without admixture was 22% higher than reference normal concrete.

  6. Freeze-out dynamics in heavy-ion collisions: Recent advances

    Indian Academy of Sciences (India)

    Francesco Becattini

    2015-05-01

    We briefly review recent advances in the subject of hadron production in relativistic heavy-ion collisions. We focus on the issues of chemical freeze-out, chemical equilibration and the role of post-hadronization inelastic collisions. From the observations collected in elementary and heavy-ion collisions, a picture emerges in which hadrons are born in chemical equilibrium at hadronization, thereafter undergoing inelastic and elastic collisions whose impact on the primordial distribution depends on the system size.

  7. The interaction between freezing tolerance and phenology in temperate deciduous trees

    Directory of Open Access Journals (Sweden)

    Yann eVitasse

    2014-10-01

    Full Text Available Temperate climates are defined by a distinct temperature seasonality with large and often unpredictable weather during any of the four seasons. To thrive in such climates, trees have to withstand a cold winter and the stochastic occurrence of freeze events during any time of the year. The physiological mechanisms trees adopt to escape, avoid and tolerate freezing temperatures include a cold acclimation in autumn, a dormancy period during winter (leafless in deciduous trees, and the maintenance of a certain freezing tolerance during dehardening in early spring. The change from one phase to the next is mediated by complex interactions between temperature and photoperiod. This review aims at providing an overview of the interplay between phenology of leaves and species-specific freezing resistance. First, we address the long-term evolutionary responses that enabled temperate trees to tolerate certain low temperature extremes. We provide evidence that short term acclimation of freezing resistance plays a crucial role both in dormant and active buds, including re-acclimation to cold conditions following warm spells. This ability declines to almost zero during leaf emergence. Second, we show that the risk that native temperate trees encounter freeze injuries is low and is confined to spring and underline that this risk might be altered by climate warming depending on species-specific phenological responses to environmental cues.

  8. Strange Hadron Resonances Freeze-Out Probes in Heavy-Ion Collisions

    CERN Document Server

    Markert, C; Rafelski, J

    2002-01-01

    Hyperon resonances are becoming an extremely useful tool allowing the study of the properties of hadronic fireballs made in heavy ion collisions. Their yield, compared to stable particles with the same quark composition, depends on hadronization conditions. The resonance's short lifetime makes them ideal probes of the fireball chemical freeze-out mechanisms. An analysis of resonance abundance in heavy ion collisions should be capable of distinguishing between possible hadronization scenarios, in particular between sudden and gradual hadronization. In this paper, we review the existing SPS and RHIC experimental data on resonance production in heavy ion collisions, and discuss in terms of both thermal and microscopic models the yields of the two observed resonances, K* and Lambda(1520). We show how freeze-out properties, namely chemical freeze-out temperature and the lifetime of the interacting hadron phase which follows, can be related to resonance yields. Finally, we apply these methods to SPS and RHIC measur...

  9. Freeze-drying of ampicillin solid lipid nanoparticles using mannitol as cryoprotectant

    Directory of Open Access Journals (Sweden)

    Faezeh Alihosseini

    2015-12-01

    Full Text Available abstract Solid lipid nanoparticles (SLNs are interesting colloidal drug-delivery systems, since they have all the advantages of the lipid and polymeric nanoparticles. Freeze-drying is a widely used process for improving the stability of SLNs. Cryoprotectants have been used to decrease SLN aggregations during freeze-drying. In this study Ampicillin was chosen to be loaded in a cholesterol carrier with nano size range. To support the stability of SLNs, freeze-drying was done using mannitol. Particle size, drug release profile and antibacterial effects were studied after freeze-drying in comparison with primary SLNs. Preparations with 5% mannitol showed the least particle size enlargement. The average particle size was 150 and 187 nm before and after freeze-drying, respectively. Freeze-drying did not affect the release profile of drug loaded nanopartilces. Also our study showed that lyophilization did not change the antimicrobial effect of ampicillin SLNs. DSC analysis showed probability of chemical interaction between ampicillin and cholesterol.

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

    Science.gov (United States)

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

    2015-12-30

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

  11. 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

  12. 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.

  13. Objective detection of subtle freezing of gait episodes in Parkinson's disease.

    NARCIS (Netherlands)

    Delval, A.; Snijders, A.H.; Weerdesteijn, V.G.M.; Duysens, J.E.J.; Defebvre, L.; Giladi, N.; Bloem, B.R.

    2010-01-01

    Freezing of gait (FOG) is a clinically defined phenomenon of Parkinson's disease (PD). Recent evidence suggests that subtle FOG episodes can be elicited in a gait laboratory using suddenly appearing obstacles during treadmill walking. We evaluated which quantitative gait parameters identify such sub

  14. Transcriptional and metabolomic analysis of Ascophyllum nodosum mediated freezing tolerance in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Nair Prasanth

    2012-11-01

    Full Text Available Abstract Background We have previously shown that lipophilic components (LPC of the brown seaweed Ascophyllum nodosum (ANE improved freezing tolerance in Arabidopsis thaliana. However, the mechanism(s of this induced freezing stress tolerance is largely unknown. Here, we investigated LPC induced changes in the transcriptome and metabolome of A. thaliana undergoing freezing stress. Results Gene expression studies revealed that the accumulation of proline was mediated by an increase in the expression of the proline synthesis genes P5CS1 and P5CS2 and a marginal reduction in the expression of the proline dehydrogenase (ProDH gene. Moreover, LPC application significantly increased the concentration of total soluble sugars in the cytosol in response to freezing stress. Arabidopsis sfr4 mutant plants, defective in the accumulation of free sugars, treated with LPC, exhibited freezing sensitivity similar to that of untreated controls. The 1H NMR metabolite profile of LPC-treated Arabidopsis plants exposed to freezing stress revealed a spectrum dominated by chemical shifts (δ representing soluble sugars, sugar alcohols, organic acids and lipophilic components like fatty acids, as compared to control plants. Additionally, 2D NMR spectra suggested an increase in the degree of unsaturation of fatty acids in LPC treated plants under freezing stress. These results were supported by global transcriptome analysis. Transcriptome analysis revealed that LPC treatment altered the expression of 1113 genes (5% in comparison with untreated plants. A total of 463 genes (2% were up regulated while 650 genes (3% were down regulated. Conclusion Taken together, the results of the experiments presented in this paper provide evidence to support LPC mediated freezing tolerance enhancement through a combination of the priming of plants for the increased accumulation of osmoprotectants and alteration of cellular fatty acid composition.

  15. 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.

  16. 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)

  17. Snow Melting and Freezing on Older Townhouses

    DEFF Research Database (Denmark)

    Nielsen, Anker; Claesson, Johan

    2011-01-01

    The snowy winter of 2009/2010 in Scandinavia prompted many newspaper articles on icicles falling from buildings and the risk this presented for people walking below. The problem starts with snow melting on the roof due to heat loss from the building. Melt water runs down the roof and some...... of it will freeze on the overhang. The rest of the water will either run off or freeze in gutters and downpipes or turn into icicles. This paper describes use of a model for the melting and freezing of snow on roofs. Important parameters are roof length, overhang length, heat resistance of roof and overhang......, outdoor and indoor temperature, snow thickness and thermal conductivity. If the snow thickness is above a specific limit value – the snow melting limit- some of the snow will melt. Another interesting limit value is the dripping limit. All the melt water will freeze on the overhang, if the snow thickness...

  18. Mathematical Modeling of the Growth and Coarsening of Ice Particles in the Context of High Pressure Shift Freezing Processes

    KAUST Repository

    Smith, N. A. S.

    2013-07-25

    High pressure shift freezing (HPSF) has been proven more beneficial for ice crystal size and shape than traditional (at atmospheric pressure) freezing.1-3 A model for growth and coarsening of ice crystals inside a frozen food sample (either at atmospheric or high pressure) is developed, and some numerical experiments are given, with which the model is validated by using experimental data. To the best of our knowledge, this is the first model suited for freezing crystallization in the context of high pressure. © 2013 American Chemical Society.

  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 2...... studies to describe freezing rates are appropriate for kaolinite aerosol particles. Mechanisms for contact freezing are briefly discussed....

  20. Isochoric and isobaric freezing of fish muscle.

    Science.gov (United States)

    Năstase, Gabriel; Lyu, Chenang; Ukpai, Gideon; Șerban, Alexandru; Rubinsky, Boris

    2017-02-19

    We have recently shown that, a living organism, which succumbs to freezing to -4 °C in an isobaric thermodynamic system (constant atmospheric pressure), can survive freezing to -4 °C in an isochoric thermodynamic system (constant volume). It is known that the mechanism of cell damage in an isobaric system is the freezing caused increase in extracellular osmolality, and, the consequent cell dehydration. An explanation for the observed survival during isochoric freezing is the thermodynamic modeling supported hypothesis that, in the isochoric frozen solution the extracellular osmolality is comparable to the cell intracellular osmolality. Therefore, cells in the isochoric frozen organism do not dehydrate, and the tissue maintains its morphological integrity. Comparing the histology of: a) fresh fish white muscle, b) fresh muscle frozen to -5 °C in an isobaric system and c) fresh muscle frozen to -5 °C I in an isochoric system, we find convincing evidence of the mechanism of cell dehydration during isobaric freezing. In contrast, the muscle tissue frozen to -5 °C in an isochoric system appears morphologically identical to fresh tissue, with no evidence of dehydration. This is the first experimental evidence in support of the hypothesis that in isochoric freezing there is no cellular dehydration and therefore the morphology of the frozen tissue remains intact.

  1. Solution-phase parallel synthesis of a pharmacophore library of HUN-7293 analogues: a general chemical mutagenesis approach to defining structure-function properties of naturally occurring cyclic (depsi)peptides.

    Science.gov (United States)

    Chen, Yan; Bilban, Melitta; Foster, Carolyn A; Boger, Dale L

    2002-05-15

    HUN-7293 (1), a naturally occurring cyclic heptadepsipeptide, is a potent inhibitor of cell adhesion molecule expression (VCAM-1, ICAM-1, E-selectin), the overexpression of which is characteristic of chronic inflammatory diseases. Representative of a general approach to defining structure-function relationships of such cyclic (depsi)peptides, the parallel synthesis and evaluation of a complete library of key HUN-7293 analogues are detailed enlisting solution-phase techniques and simple acid-base liquid-liquid extractions for isolation and purification of intermediates and final products. Significant to the design of the studies and unique to solution-phase techniques, the library was assembled superimposing a divergent synthetic strategy onto a convergent total synthesis. An alanine scan and N-methyl deletion of each residue of the cyclic heptadepsipeptide identified key sites responsible for or contributing to the biological properties. The simultaneous preparation of a complete set of individual residue analogues further simplifying the structure allowed an assessment of each structural feature of 1, providing a detailed account of the structure-function relationships in a single study. Within this pharmacophore library prepared by systematic chemical mutagenesis of the natural product structure, simplified analogues possessing comparable potency and, in some instances, improved selectivity were identified. One potent member of this library proved to be an additional natural product in its own right, which we have come to refer to as HUN-7293B (8), being isolated from the microbial strain F/94-499709.

  2. Explant culture of mouse embryonic whole lung, isolated epithelium, or mesenchyme under chemically defined conditions as a system to evaluate the molecular mechanism of branching morphogenesis and cellular differentiation.

    Science.gov (United States)

    Del Moral, Pierre-Marie; Warburton, David

    2010-01-01

    Lung primordial specification as well as branching morphogenesis, and the formation of various pulmonary cell lineages, requires a specific interaction of the lung endoderm with its surrounding mesenchyme and mesothelium. Lung mesenchyme has been shown to be the source of inductive signals for lung branching morphogenesis. Epithelial-mesenchymal-mesothelial interactions are also critical to embryonic lung morphogenesis. Early embryonic lung organ culture is a very useful system to study epithelial-mesenchymal interactions. Both epithelial and mesenchymal morphogenesis proceed under specific conditions that can be readily manipulated in this system (in the absence of maternal influence and blood flow). More importantly this technique can be readily done in a serumless, chemically defined culture media. Gain and loss of function can be achieved using expressed proteins, recombinant viral vectors, and/or analysis of transgenic mouse strains, antisense RNA, as well as RNA interference gene knockdown. Additionally, to further study epithelial-mesenchymal interactions, the relative roles of epithelium versus mesenchyme signaling can also be determined using tissue recombination (e.g., epithelial and mesenchymal separation) and microbead studies.

  3. A Rapid Compression Expansion Machine (RCEM) for studying chemical kinetics: Experimental principle and first applications

    CERN Document Server

    Werler, Marc; Maas, Ulrich

    2016-01-01

    A novel extension of a rapid compression machine (RCM), namely a Rapid Compression Expansion Machine (RCEM), is described and its use for studying chemical kinetics is demonstrated. Like conventional RCMs, the RCEM quickly compresses a fuel/air mixture by pushing a piston into a cylinder; the resulting high temperatures and pressures initiate chemical reactions. In addition, the machine can rapidly expand the compressed gas in a controlled way by pulling the piston outwards again. This freezes chemical activity after a pre-defined reaction duration, and therefore allows a convenient probe sampling and ex-situ gas analysis of stable species. The RCEM therefore is a promising instrument for studying chemical kinetics, including also partially reacted fuel/air mixtures. The setup of the RCEM, its experimental characteristics and its use for studying chemical reactions are outlined in detail. To allow comparisons of RCEM results with predictions of chemical reaction mechanisms, a simple numerical model of the RCE...

  4. Search for QGP and Thermal Freeze-out of Strange Hadrons

    OpenAIRE

    Torrieri, Giorgio; Rafelski, Johann

    2000-01-01

    After reviewing the observables of QGP we perform an analysis of m_T spectra of strange hadrons measured as function of centrality in 156AGeV Pb--Pb interactions. We show that there is a good agreement between the chemical and thermal freeze-out conditions, providing additional evidence for the formation and sudden disintegration of a supercooled QGP fireball.

  5. Variability of Stepping during a Virtual Reality Paradigm in Parkinson's Disease Patients with and without Freezing of Gait.

    Directory of Open Access Journals (Sweden)

    Moran Gilat

    Full Text Available Freezing of gait is a common and debilitating symptom affecting many patients with advanced Parkinson's disease. Although the pathophysiology of freezing of gait is not fully understood, a number of observations regarding the pattern of gait in patients with this symptom have been made. Increased 'Stride Time Variability' has been one of the most robust of these features. In this study we sought to identify whether patients with freezing of gait demonstrated similar fluctuations in their stepping rhythm whilst performing a seated virtual reality gait task that has recently been used to demonstrate the neural correlate of the freezing phenomenon.Seventeen patients with freezing and eleven non-freezers performed the virtual reality task twice, once whilst 'On' their regular Parkinsonian medication and once in their practically defined 'Off' state.All patients displayed greater step time variability during their 'Off' state assessment compared to when medicated. Additionally, in the 'Off' state, patients with freezing of gait had greater step time variability compared to non-freezers. The five steps leading up to a freezing episode in the virtual reality environment showed a significant increase in step time variability although the final three steps preceding the freeze were not characterized by a progressive shortening of latency.The results of this study suggest that characteristic features of gait disturbance observed in patients with freezing of gait can also be demonstrated with a virtual reality paradigm. These findings suggest that virtual reality may offer the potential to further explore the freezing phenomenon in Parkinson's disease.

  6. Variability of Stepping during a Virtual Reality Paradigm in Parkinson’s Disease Patients with and without Freezing of Gait

    Science.gov (United States)

    Gilat, Moran; Shine, James M.; Bolitho, Samuel J.; Matar, Elie; Kamsma, Yvo P. T.; Naismith, Sharon L.; Lewis, Simon J. G.

    2013-01-01

    Background Freezing of gait is a common and debilitating symptom affecting many patients with advanced Parkinson’s disease. Although the pathophysiology of freezing of gait is not fully understood, a number of observations regarding the pattern of gait in patients with this symptom have been made. Increased ‘Stride Time Variability’ has been one of the most robust of these features. In this study we sought to identify whether patients with freezing of gait demonstrated similar fluctuations in their stepping rhythm whilst performing a seated virtual reality gait task that has recently been used to demonstrate the neural correlate of the freezing phenomenon. Methods Seventeen patients with freezing and eleven non-freezers performed the virtual reality task twice, once whilst ‘On’ their regular Parkinsonian medication and once in their practically defined ‘Off’ state. Results All patients displayed greater step time variability during their ‘Off’ state assessment compared to when medicated. Additionally, in the ‘Off’ state, patients with freezing of gait had greater step time variability compared to non-freezers. The five steps leading up to a freezing episode in the virtual reality environment showed a significant increase in step time variability although the final three steps preceding the freeze were not characterized by a progressive shortening of latency. Conclusions The results of this study suggest that characteristic features of gait disturbance observed in patients with freezing of gait can also be demonstrated with a virtual reality paradigm. These findings suggest that virtual reality may offer the potential to further explore the freezing phenomenon in Parkinson’s disease. PMID:23805270

  7. 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.

  8. Definable deduction relation

    Institute of Scientific and Technical Information of China (English)

    张玉平

    1999-01-01

    The nonmonotonic deduction relation in default reasoning is defined with fixed point style, which has the many-extension property that classical logic is not possessed of. These two kinds of deductions both have boolean definability property, that is, their extensions or deductive closures can be defined by boolean formulas. A generalized form of fixed point method is employed to define a class of deduction relations, which all have the above property. Theorems on definability and atomless boolean algebras in model theory are essential in dealing with this assertion.

  9. A new freeze casting technique for ceramics

    Science.gov (United States)

    Araki, Kiyoshi

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

  10. The Potential for Achieving Freeze/Thaw Protection in Concrete through the addition of Rubber Crumb

    OpenAIRE

    Richardson, Alan; Coventry, Kathryn; Pienaar, Jaques

    2011-01-01

    This paper evaluates the use of recycled rubber tyres in the form of rubber crumb as a freeze/thaw protection agent when used in concrete. Reusing scrap tyres in the form of rubber crumb, in concrete could benefi t the environment by reducing landfi ll and reducing the chemical usage of air entraining agents. The test procedure involved subjecting concrete to freeze/thaw cycles at 5 days of age. Thawing was conducted in water to ensure full saturation of pores and maximum stress on the concre...

  11. 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).

  12. Historically defined autobiographical periods

    DEFF Research Database (Denmark)

    Brown, Norman R.; Hansen, Tia G. B.; Lee, Peter J.;

    2012-01-01

    The chapter reviews a research programme that has demonstrated the existence of historically defined autobiographical periods and identified the conditions that bring them about. Data from four samples of World War II-generation adults show that historically defined autobiographical periods endure...... over time and theoretical implications are discussed, notably by introducing a new approach to autobiographical memory, Transition Theory, which assumes that autobiographical memory is organized by transitional events that can be selfinitiated or externally imposed - historically defined...

  13. Three years of antibacterial consumption in Indonesian Community Health Centers: The application of anatomical therapeutic chemical/defined daily doses and drug utilization 90% method to monitor antibacterial use

    Directory of Open Access Journals (Sweden)

    Ivan S Pradipta

    2015-01-01

    Full Text Available Context: Irrational use of antibacterial drugs in Community Health-Care Centers (CHCs may lead to increased resistance, morbidity, and mortality. Aims: The aim of this study was to determine patterns of antibacterial use at CHCs in a district of Indonesia and use this as data for an antibiotic policy. Settings and Design: The observational-descriptive study was conducted in a district of Indonesia to obtain antibacterial use from 2008 to 2010. Subjects and Methods: The data obtained from the report on the use of medicines were classified and processed using the anatomical therapeutic chemical (ATC and defined daily doses (DDD method, with DDD/1000 patients as a unit measurement. The number of patients was obtained from attending patients in that research period. The most abundant antibacterial drugs use segment was identified by the drug utilization 90% (DU90% method. Statistical Analysis Used: Descriptive analysis were performed in this study. Results: Fourteen kinds of antibacterial drugs were used in 61 CHCs. The total of antibacterial drug use during the period 2008-2010 was 871.36 DDD/1000 patients/day. Declining antibacterial use was observed between 2008 and 2010. Six kinds of antibacterial drugs were the most commonly used. The data show that the average use per visit was as high as 24.41 DDD. Conclusions: Amoxicillin, sulfamethoxazole and trimethoprim are antibacterials that have to be reconsidered by physicians for use in the Bandung CHC. The high use of antibacterial drugs, as described in the study, can be used as reference to develop an antimicrobial stewardship program and increase awareness of resistance, adverse drug reaction and drug interaction of antibacterial drugs.

  14. 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.

  15. 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.

  16. Optimization of freeze-drying condition of amikacin solid lipid nanoparticles using D-optimal experimental design.

    Science.gov (United States)

    Varshosaz, Jaleh; Ghaffari, Solmaz; Khoshayand, Mohammad Reza; Atyabi, Fatemeh; Dehkordi, Abbas Jafarian; Kobarfard, Farzad

    2012-01-01

    Amikacin as an aminoglycoside antibiotic was chosen to be loaded in a cholesterol carrier with nanoparticle size and sustained release profile to increase the dose interval of amikacin and reduce side-effects. To support the stability of solid lipid nanoparticles (SLNs), freeze-drying was suggested. Factors affecting the freeze-drying process in the present study included the type and concentration of cryoprotectants. Pre-freezing temperature effects were also studied on particle size of SLNs of amikacin. In some preliminary experiments, important factors which influenced the particle size of SLNs after lyophilization were selected and a D-optimal design was applied to optimize the freeze-drying conditions in the production of SLNs with minimum particle size growth after freeze-drying. Zeta potential, DSC thermograms, release profiles and morphology of the optimized particles were studied before and after freeze-drying. Results showed sucrose changed the particle size of SLNs of amikacin from 149 ± 4 nm to 23.9 ± 16.7 nm; in that situation, the absolute value of zeta potential changed from 1 ± 0.7 mV to 13 ± 4 mV. The release profiles showed a sustained release behavior of the loaded drug that did not change significantly before and after freeze-drying, but a burst effect was seen after it in the first 2 h. DSC analysis showed chemical interaction between amikacin and cholesterol.

  17. Effect of freezing on microstructure and degree of syneresis in differently formulated fruit fillings.

    Science.gov (United States)

    Cropotova, Janna; Tylewicz, Urszula; Dellarosa, Nicolò; Laghi, Luca; Romani, Santina; Dalla Rosa, Marco

    2016-03-15

    This study describes the syneresis and its effect on microstructure in fruit fillings within a wide range of the total soluble solids content and with or without hydrocolloids upon freezing. Linear models showed the relevance of the addition of pectin and gellan gum to fillings to prevent syneresis, increasing the water-holding capacity especially after freezing. Microstructural experiments by means of NMR spin-spin relaxometry combined with fluorescence microscopy allowed to observe that the continuous hydrocolloid gel, containing the dispersed solution of native fruit parts with the addition of inulin and sugars, changed its structure/distribution according to the amount of each ingredient and due to the freezing process. Relaxometry results confirmed that hydrocolloids strength was correlated (R(2)>0.92) with water-holding capacity, due to a relationship between the signal given by the water chemically exchanging with biopolymers, and the changes in the degree of syneresis.

  18. Características microbiológicas e físico-químicas do leite de cabra submetido à pasteurização lenta pós-envase e ao congelamento Microbiological and physical-chemical characteristics of goat milk after low temperature time pasteurization and freezing

    Directory of Open Access Journals (Sweden)

    Patricia Vilhena Dias de Andrade

    2008-08-01

    Full Text Available O objetivo principal deste trabalho foi avaliar o efeito da pasteurização lenta (65°C 30min-1 em banho-maria e do congelamento (-18°C, seguido de estocagem por uma semana (-18°C, sobre as características microbiológicas e físico-químicas do leite de cabra pré-embalado. Quinze amostras individuais de leite de cabra foram analisadas antes e após o processamento, realizado no próprio capril. A pasteurização lenta mostrou-se eficaz na redução da contaminação por mesófilos, psicrotróficos e fungos, mas a baixa contagem de coliformes fecais e totais do leite cru não proporcionou a mesma eficácia neste grupo de bactérias. O armazenamento do leite congelado durante uma semana não alterou a sua qualidade microbiológica. Não se observou influência significativa do processamento térmico sobre as concentrações dos principais constituintes do leite ou sobre as propriedades físico-químicas analisadas. Os resultados obtidos nesse experimento mostraram também que um equipamento de leitura infra-vermelha calibrado com leite bovino pode ser usado para a determinação dos teores de gordura e proteína do leite de cabra.The aim of this trial was to evaluate the effect of water bath low temperature long time pasteurization (65°C 30 min-1 and freezing (-18°C followed by one-week storage (-18°C on the physical-chemical characteristics of goat milk. Fifteen individual milk samples were analyzed before and after being processed by the producer himself. Thermal processing applied was efficient for reducing mesophilic, psychrotrophic, molds and yeasts contamination, even though the low total and fecal coliform counts in raw milk did not allow the same statement considering that bacteria group. Thermal processing had no significant influence on the main constituents' concentrations or on the analyzed physical-chemical properties. The results obtained in this study also showed that infrared equipment calibrated with cow milk could be

  19. Freeze substitution in 3 hours or less.

    Science.gov (United States)

    McDonald, K L; Webb, R I

    2011-09-01

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

  20. 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).

  1. 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.

  2. Chemical freeze-out conditions in hadron resonance gas

    CERN Document Server

    Vovchenko, V; Satarov, L M; Stoecker, H

    2016-01-01

    The hadron resonance gas model with hadron-type dependent eigenvolume corrections is employed to fit the hadron yield data of the NA49 collaboration for central Pb+Pb collisions at the c.m. energy per nucleon pair Ecm=6.3, 7.6, 8.8, 12.3, and 17.3 GeV, the hadron midrapidity yield data of the STAR collaboration for Au+Au collisions at Ecm=200 GeV, and the hadron midrapidity yield data of the ALICE collaboration for Pb+Pb collisions at Ecm=2760 GeV. The influence of the eigenvolume corrections is studied.

  3. Defining Legal Moralism

    DEFF Research Database (Denmark)

    Thaysen, Jens Damgaard

    2015-01-01

    This paper discusses how legal moralism should be defined. It is argued that legal moralism should be defined as the position that “For any X, it is always a pro tanto reason for justifiably imposing legal regulation on X that X is morally wrong (where “morally wrong” is not conceptually equivalent...

  4. Freeze-out conditions for production of resonances, hadronic molecules, and light nuclei

    CERN Document Server

    Cho, Sungtae; Lee, Su Houng

    2015-01-01

    We investigate the freeze-out conditions of a particle in an expanding system of interacting particles in order to understand the productions of resonances, hadronic molecules and light nuclei in heavy ion collisions. Applying the kinetic freeze-out condition with explicit hydrodynamic calculations for the expanding hadronic phase to the daughter particles of $K^*$ mesons, we find that the larger suppression of the yield ratio of $K^*/K$ at LHC than at RHIC compared to the expectations from the statistical hadronization model based on chemical freeze-out parameters reflects the lower kinetic freeze-out temperature at LHC than at RHIC. Furthermore, we point out that for the light nuclei or hadronic molecules that are bound, the yields are affected by the freeze-out condition of the respective particle in the hadronic matter, which leads to the observation that the deuteron production yields are independent of the size of deuteron, and depend only on the number of ground state constituents.

  5. Microstructure characterisation of freeze linings formed in a copper slag cleaning slag

    Directory of Open Access Journals (Sweden)

    Jansson J.

    2015-01-01

    Full Text Available The initial growth rate of freeze linings on water-cooled elements submerged in molten iron silicate slag is fast. The freeze lining microstructure forming on water cooled steel surface in a high-silica, slag cleaning furnace slag of a direct-to-blister copper smelter is mostly glassy or amorphous. It contains 5-30 μm magnetite crystals, very small and larger copper droplets as well as small magnetite and silicate nuclei embedded in the glassy silica-rich matrix. Chemically the formed freeze linings are more silica-rich than the slag from which they were generated. Magnetite (spinel is the primary phase of the solidifying SCF slag but it does not form a continuous network through the freeze lining. Its strength is given by the intergranular silica-rich phase which initially is glassy or microcrystalline. Due to only partial slag reduction in the SCF process, large magnetite crystals are present in the freeze lining and seem to interact physically with copper droplets.

  6. Freezing of a stripe liquid.

    Science.gov (United States)

    Lee, S-H; Tranquada, J M; Yamada, K; Buttrey, D J; Li, Q; Cheong, S-W

    2002-03-25

    The existence of a stripe-liquid phase in a layered nickelate, La(1.725)Sr(0.275)NiO(4), is demonstrated through neutron scattering measurements. We show that incommensurate magnetic fluctuations evolve continuously through the charge-ordering temperature, although an abrupt decrease in the effective damping energy is observed on cooling through the transition. The energy and momentum dependence of the magnetic scattering are parametrized with a damped-harmonic-oscillator model describing overdamped spin waves in the antiferromagnetic domains defined instantaneously by charge stripes.

  7. Freezing of a Stripe Liquid

    Science.gov (United States)

    Lee, S.-H.; Tranquada, J. M.; Yamada, K.; Buttrey, D. J.; Li, Q.; Cheong, S.-W.

    2002-03-01

    The existence of a stripe-liquid phase in a layered nickelate, La1.725Sr0.275NiO4, is demonstrated through neutron scattering measurements. We show that incommensurate magnetic fluctuations evolve continuously through the charge-ordering temperature, although an abrupt decrease in the effective damping energy is observed on cooling through the transition. The energy and momentum dependence of the magnetic scattering are parametrized with a damped-harmonic-oscillator model describing overdamped spin waves in the antiferromagnetic domains defined instantaneously by charge stripes.

  8. Regulation of SMAD transcription factors during freezing in the freeze tolerant wood frog, Rana sylvatica.

    Science.gov (United States)

    Aguilar, Oscar A; Hadj-Moussa, Hanane; Storey, Kenneth B

    2016-11-01

    The wood frog, Rana sylvatica, survives sub-zero winter temperatures by undergoing full body freezing for weeks at a time, during which it displays no measurable brain activity, no breathing, and a flat-lined heart. Freezing is a hypometabolic state characterized by a global suppression of gene expression that is elicited in part by transcription factors that coordinate the activation of vital pro-survival pathways. Smad transcription factors respond to TGF-β signalling and are involved in numerous cellular functions from development to stress. Given the identity of genes they regulate, we hypothesized that they may be involved in coordinating gene expression during freezing. Protein expression of Smad1/2/3/4/5 in response to freezing was examined in 24h frozen and 8h thawed wood frog tissues using western immunoblotting, with the determination of subcellular localization in muscle and liver tissues. Transcript levels of smad2, smad4 and downstream genes (serpine1, myostatin, and tsc22d3) were measured by RT-PCR. Tissue-specific responses were observed during freezing where brain, heart, and liver had elevated levels of pSmad3, and skeletal muscle and kidneys had increased levels of pSmad1/5 and pSmad2 during freeze/thaw cycle, while protein and transcript levels remained constant. There were increases in nuclear levels of pSmad2 in muscle and pSmad3 in liver. Transcript levels of serpine1 were induced in heart, muscle, and liver, myostatin in muscle, and tsc22d3 in heart, and liver during freezing. These results suggest a novel freeze-responsive activation of Smad proteins that may play an important role in coordinating pro-survival gene networks necessary for freeze tolerance.

  9. Chemical Effects during Storage of Frozen Foods.

    Science.gov (United States)

    Powrie, W. D.

    1984-01-01

    Discusses (1) characteristics, interrelationships, and distribution of food constituents (including water) in unfrozen food systems; (2) the freezing process; and (3) chemical changes in food during frozen storage. Protein alterations and lipid oxidation are emphasized. (JN)

  10. Freeze-out Conditions in Heavy Ion Collisions from QCD Thermodynamics

    CERN Document Server

    Bazavov, A; Hegde, P; Kaczmarek, O; Karsch, F; Laermann, E; Mukherjee, Swagato; Petreczky, P; Schmidt, C; Smith, D; Soeldner, W; Wagner, M

    2012-01-01

    We present a determination of chemical freeze-out conditions in heavy ion collisions based on ratios of cumulants of net electric charge fluctuations. These ratios can reliably be calculated in lattice QCD for a wide range of chemical potential values by using a next-to-leading order Taylor series expansion around the limit of vanishing baryon, electric charge and strangeness chemical potentials. From a computation of up to fourth order cumulants and charge correlations we first determine the strangeness and electric charge chemical potentials that characterize freeze-out conditions in a heavy ion collision and confirm that in the temperature range 150 MeV < T < 170 MeV the hadron resonance gas model provides good approximations for these parameters that agree with QCD calculations on the (5-15)% level. We then show that a comparison of lattice QCD results for ratios of up to third order cumulants of electric charge fluctuations with experimental results allows to extract the freeze-out baryon chemical ...

  11. 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.

  12. Comparison of a production process in a membrane-aerated stirred tank and up to 1000-L airlift bioreactors using BHK-21 cells and chemically defined protein-free medium.

    Science.gov (United States)

    Hesse, Friedemann; Ebel, Maria; Konisch, Nadine; Sterlinski, Reinhard; Kessler, Wolfgang; Wagner, Roland

    2003-01-01

    consumption rate. The results of this study clearly demonstrate the applicability of a protein-free chemically defined medium for the production of recombinant proteins with BHK cells in airlift bioreactors.

  13. Definably amenable NIP groups

    OpenAIRE

    Chernikov, Artem; Simon, Pierre

    2015-01-01

    We study definably amenable NIP groups. We develop a theory of generics, showing that various definitions considered previously coincide, and study invariant measures. Applications include: characterization of regular ergodic measures, a proof of the conjecture of Petrykowski connecting existence of bounded orbits with definable amenability in the NIP case, and the Ellis group conjecture of Newelski and Pillay connecting the model-theoretic connected component of an NIP group with the ideal s...

  14. Defining Documentary Film

    DEFF Research Database (Denmark)

    Juel, Henrik

    2006-01-01

    A discussion of various attemts at defining documentary film regarding form, content, truth, stile, genre or reception - and a propoposal of a positive list of essential, but non-exclusive characteristica of documentary film......A discussion of various attemts at defining documentary film regarding form, content, truth, stile, genre or reception - and a propoposal of a positive list of essential, but non-exclusive characteristica of documentary film...

  15. 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

  16. Asset Freezing: Smart Sanction or Criminal Charge?

    NARCIS (Netherlands)

    Broek, Melissa van den; Hazelhorst, Monique; Zanger, Wouter de

    2011-01-01

    In this article the question is asked whether asset freezing can be qualified as a criminal charge within the meaning of Article6 ECHR and if yes, what effects this qualification may have on the legislative framework on so called smart sanctions. Byanalysing Community and EU law and case law of the

  17. 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.

  18. 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

  19. 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...

  20. Nucleation Pathways For Freezing Of Two Grades Of Zirconium

    Science.gov (United States)

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

    1996-01-01

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

  1. 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.

  2. 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.

  3. 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.

  4. 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...

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

    Science.gov (United States)

    Watanabe, Keishiro; Okamoto, Jun; Kurita, Takaaki

    2006-01-01

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

  6. Lattice QCD results on cumulant ratios at freeze-out

    CERN Document Server

    Karsch, Frithjof

    2016-01-01

    Ratios of cumulants of net proton-number fluctuations measured by the STAR Collaboration show strong deviations from a skellam distribution, which should describe thermal properties of cumulant ratios, if proton-number fluctuations are generated in equilibrium and a hadron resonance gas (HRG) model would provide a suitable description of thermodynamics at the freeze-out temperature. We present some results on sixth order cumulants entering the calculation of the QCD equation of state at non-zero values of the baryon chemical potential (mu_B) and discuss limitations on the applicability of HRG thermodynamics deduced from a comparison between QCD and HRG model calculations of cumulants of conserved charge fluctuations. We show that basic features of the $\\mu_B$-dependence of skewness and kurtosis ratios of net proton-number fluctuations measured by the STAR Collaboration resemble those expected from a O(mu_B^2) QCD calculation of the corresponding net baryon-number cumulant ratios.

  7. Nouns to Define Homophobia

    Directory of Open Access Journals (Sweden)

    Adalberto Campo Arias

    2013-09-01

    Full Text Available Background. The term ‘homophobia’ was introduced in the academic context more than 40 years ago. However, its meaning has changed over time. Objective. To review the nouns used in the last twelve years to define homophobia. Methodology. The authors conducted a systematic search in Medline through Pubmed that included editorials, letters to editors, comments and narrative reviews, in English and Spanish. A qualitative analysis (Grounded theory was applied to analyze nouns used to define homophobia since 2001 through 2012. Results. Authors reviewed three papers including ten nouns to define homophobia, the most common noun was fear. The terms were grouped into two domains: negative attitude and discomfort with homosexuality. Conclusion. Fear is the most used word to describe homophobia. The terms were grouped into two domains: negative attitude and discomfort toward homosexuality.

  8. Can play be defined?

    DEFF Research Database (Denmark)

    Eichberg, Henning

    2015-01-01

    Can play be defined? There is reason to raise critical questions about the established academic demand that at phenomenon – also in humanist studies – should first of all be defined, i.e. de-lineated and by neat lines limited to a “little box” that can be handled. The following chapter develops t....... Human beings can very well understand play – or whatever phenomenon in human life – without defining it........ The academic imperative of definition seems to be linked to the positivistic attempts – and produces sometimes monstrous definitions. Have they any philosophical value for our knowledge of what play is? Definition is not a universal instrument of knowledge-building, but a culturally specific construction...

  9. Defining "intermittent UVR exposure"

    DEFF Research Database (Denmark)

    Bodekær, Mette; Philipsen, Peter Alshede; Petersen, Bibi Øager;

    2016-01-01

    to define and quantify “intermittent UVR exposure” by an objective measure. Methods: A broad study population of adults and children had data collected during a summer period. Data were personal UVR dosimetry measurements, from which the number of “intermittent days” was derived, sun behaviour diaries.......001). The corresponding numbers for prediction of nevi and lentigo density by retrospective questionnaire data was lower (R2 = 0.11, R2 = 0.26, p defined objective measure of intermittent UVR exposure. This measure may provide a better prediction of solar skin damage and CMM...

  10. 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

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

    Science.gov (United States)

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

  12. Defining Mathematical Giftedness

    Science.gov (United States)

    Parish, Linda

    2014-01-01

    This theoretical paper outlines the process of defining "mathematical giftedness" for a present study on how primary school teaching shapes the mindsets of children who are mathematically gifted. Mathematical giftedness is not a badge of honour or some special value attributed to a child who has achieved something exceptional.…

  13. Software Defined Networking

    DEFF Research Database (Denmark)

    Caba, Cosmin Marius

    resources are limited. Hence, to counteract this trend, current QoS mechanisms must become simpler to deploy and operate, in order to motivate NSPs to employ QoS techniques instead of overprovisioning. Software Defined Networking (SDN) represents a paradigm shift in the way telecommunication and data...

  14. Defining Data Science

    OpenAIRE

    Zhu, Yangyong; Xiong, Yun

    2015-01-01

    Data science is gaining more and more and widespread attention, but no consensus viewpoint on what data science is has emerged. As a new science, its objects of study and scientific issues should not be covered by established sciences. Data in cyberspace have formed what we call datanature. In the present paper, data science is defined as the science of exploring datanature.

  15. On Defining Mass

    Science.gov (United States)

    Hecht, Eugene

    2011-01-01

    Though central to any pedagogical development of physics, the concept of mass is still not well understood. Properly defining mass has proven to be far more daunting than contemporary textbooks would have us believe. And yet today the origin of mass is one of the most aggressively pursued areas of research in all of physics. Much of the excitement…

  16. Defining in Classroom Activities.

    Science.gov (United States)

    Mariotti, Maria Alessandra; Fischbein, Efraim

    1997-01-01

    Discusses some aspects of the defining process in geometrical context in the reference frame of the theory of "figural concepts." Presents analysis of some examples taken from a teaching experiment at the sixth-grade level. Contains 30 references. (Author/ASK)

  17. Defining Game Mechanics

    DEFF Research Database (Denmark)

    Sicart (Vila), Miguel Angel

    2008-01-01

    This article defins game mechanics in relation to rules and challenges. Game mechanics are methods invoked by agents for interacting with the game world. I apply this definition to a comparative analysis of the games Rez, Every Extend Extra and Shadow of the Colossus that will show the relevance...... of a formal definition of game mechanics. Udgivelsesdato: Dec 2008...

  18. 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)

  19. The curvature of the freeze-out line in heavy ion collisions

    CERN Document Server

    Bazavov, A; Hegde, P; Kaczmarek, O; Karsch, F; Laermann, E; Mukherjee, Swagato; Ohno, H; Petreczky, P; Schmidt, C; Sharma, S; Soeldner, W; Wagner, M

    2015-01-01

    We calculate the mean and variance of net-baryon number and net-electric charge distributions from Quantum Chromodynamics (QCD) using a next-to-leading order Taylor expansion in terms of temperature and chemical potentials. We compare these expansions with experimental data from STAR and PHENIX, determine the freeze-out temperature in the limit of vanishing baryon chemical potential, and, for the first time, constrain the curvature of the freeze-out line through a direct comparison between experimental data on net-charge fluctuations and a QCD calculation. We obtain a bound on the curvature coefficient, kappa_2^f < 0.011, that is compatible with lattice QCD results on the curvature of the QCD transition line.

  20. Ice Freezing In Storfjorden From Four Winters of Satellite and In Situ Observations

    Science.gov (United States)

    Skogseth, R.; Haugan, P. M.

    ERS-2-SAR images and in situ meteorological and hydrographic data have been col- lected during the freezing periods 1999/2000 and 2000/2001, extending the earlier study periods 1997/1998 and 1998/1999 [(Haarpaintner et al., 2001), (Haarpaintner et al., 2000)]. The study area Storfjorden is situated between the islands Spitsbergen, Barentöya and Edgeöya in the Svalbard Archipelago and is defined by an 115m deep sill at 76 45' N in the south and by a shallow bank Storfjordbanken in the south- east. Heleysundet and Freemansundet, two sounds in the north and northeast, connect Storfjorden with northwestern Barents Sea, and strong tidal currents are present in these sounds. A latent coastal polynya situated inside Storfjorden on the leeside off Edgeöya makes Storfjorden an "ice factory" due to the large heat flux in the polynya region. Brine-enriched Shelf Water (BSW), which is formed inside Storfjorden due to brine release from ice freezing, will have characteristics dependent on source wa- ter, ice production and position of the polynya inside Storfjorden. Onset of freezing was found from SAR, AVHRR and SSMI images available for Storfjorden. Classi- fication of fast ice, pack ice and polynya (open water and thin/new ice) was done from available SAR images in the four freezing periods. An existing one-dimensional polynya width model was used to calculate ice production of fast ice, pack ice, thin ice and frazil ice. Results from the SAR image classification and the polynya width model were compared to test and modify the model using the four-year time series. Also, sensitivity tests of the polynya width model were performed. Data from exten- sive hydrographic surveys in Storfjorden (Skogseth, Haugan and Nøst: Water mass transformations in Storfjorden, submitted EGS 2002) gives initial conditions before onset of freezing and conditions during and after freezing for each freezing period. Summer and autumn data give the resulting BSW characteristics after each

  1. When do particle ratios freeze out in relativistic heavy ion collisions?

    Science.gov (United States)

    Humanic, Thomas; Bellwied, Rene

    1999-10-01

    The systematics of CERN SPS data for transverse mass distributions have been shown to imply that thermal equilibrium is achieved at freeze out in these collisions. This conclusion is based on the observation that for p+p, S+S, and Pb+Pb collisions freeze out occurs at a single temperature for all particle species measured if one assumes a certain uniform expansion velocity after hadronization for each colliding system [1]. A recent final- state rescattering calculation for SPS Pb+Pb collisions has shown that these systematics can be described as a consequence of particle rescattering where the system is assumed initially (i.e. at hadronization) to have a common temperature for all particles and no initial expansion velocity [2]. In addition to kinetic observables, it is equally interesting to investigate the time dependence of particle abundances through particle ratios in such a calculation. Two questions immediately arise: 1) is chemical equilibrium established in these collisions, and 2) when does chemical freeze out occur with respect to thermal freeze out for different particle ratios? How rescattering influences particle ratios is clearly of interest if one would like to deduce information about the hadronization stage of the collision from particle ratios measured at freeze out. For the present work we will show results for strange and non-strange particle ratios within the context of a version of the dynamic transport code used in Ref. [2]. [1] NA44 colaboration, I.G. Bearden et al., Phys. Rev. Lett. 78,2080(1997), [2] T. J. Humanic, Phys. Rev. C 57,866(1998)

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

    Science.gov (United States)

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

    2016-04-01

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

  3. Volume versus surface nucleation in freezing aerosols

    Science.gov (United States)

    Sigurbjörnsson, Ómar F.; Signorell, Ruth

    2008-05-01

    The present study puts an end to the ongoing controversy regarding volume versus surface nucleation in freezing aerosols: Our study on nanosized aerosol particles demonstrates that current state of the art measurements of droplet ensembles cannot distinguish between the two mechanisms. The reasons are inherent experimental uncertainties as well as approximations used to analyze the kinetics. The combination of both can lead to uncertainties in the rate constants of two orders of magnitude, with important consequences for the modeling of atmospheric processes.

  4. [Equipment for spray-freezing in ophthalmology].

    Science.gov (United States)

    Anders, M; Matthes, R

    1991-05-01

    The authors discuss the theoretical background of the method of spray/freezing for destructive processes and their advantages. They demonstrate a cryo-apparatus IKG 3 for liquid nitrogen which is part of the Dresden equipment and was elaborated by the department for cryomedicine of the "Carl Gustav Carus" Academy in cooperation with the Technical University in Dresden. The apparatus produces a fine dispensable spray of the cooling mixture and permits treatment even of small tissue areas.

  5. Defining Legal Moralism

    DEFF Research Database (Denmark)

    Thaysen, Jens Damgaard

    2015-01-01

    This paper discusses how legal moralism should be defined. It is argued that legal moralism should be defined as the position that “For any X, it is always a pro tanto reason for justifiably imposing legal regulation on X that X is morally wrong (where “morally wrong” is not conceptually equivalent...... to “harmful”)”. Furthermore, a distinction between six types of legal moralism is made. The six types are grouped according to whether they are concerned with the enforcement of positive or critical morality, and whether they are concerned with criminalising, legally restricting, or refraining from legally...... protecting morally wrong behaviour. This is interesting because not all types of legal moralism are equally vulnerable to the different critiques of legal moralism that have been put forth. Indeed, I show that some interesting types of legal moralism have not been criticised at all....

  6. Define Digital Vernacular

    Institute of Scientific and Technical Information of China (English)

    刘佳; 李海英; James Stevens; Rough Nelson

    2014-01-01

    As science and technology developed, the tools of humans developed from humans’hands, to mechanical and digital technologies. The tools influ-ence almost everything in the humans’world, so does vernacular. The digital vernacular could be understood as using digital technology to vernacular; the digital means technologies. It also could be understood as doing vernacular in a digital way;the digital means data and information, in other words it can be seeking truth from facts. Define digital vernacular is not only what is digital vernacular, but also about how to do the digital vernacular and what kind of attitude we should hold to-ward the digital vernacular. Define digital vernacular as both thinking and doing.

  7. Freeze/thaw protection of concrete with optimum rubber crumb content

    OpenAIRE

    Richardson, Alan; Coventry, Kathryn; Ward, Gavin

    2012-01-01

    This research looks at utilising an optimum quantity of rubber crumb as an air entraining ad-mixture in concrete, thus providing maximum freeze-thaw protection and maximum strength. Microscopic and chemical analysis was carried out on the rubber sample to investigate how rubber crumb entrains air and reacts with the surrounding concrete. The work contained two pilot studies that informed the main test methodology. The pilot studies examined the air content/compressive strength relationship (1...

  8. Disaggregating meteorites by automated freeze thaw.

    Science.gov (United States)

    Charles, Christopher R J

    2011-06-01

    An automated freeze-thaw (AFT) instrument for disaggregating meteorites is described. Meteorite samples are immersed in 18.2 MΩ water and hermetically sealed in a clean 30 ml Teflon vial. This vial and its contents are dipped between baths of liquid nitrogen and hot water over a number of cycles by a dual-stepper motor system controlled by LabView. Uniform and periodic intervals of freezing and thawing induce multiple expansions and contractions, such that cracks propagate along natural flaws in the meteorite for a sufficient number of AFT cycles. For the CR2 chondrite NWA801, the boundaries between different phases (i.e., silicates, metal, matrix) became progressively weaker and allowed for an efficient recovery of 500 individual chondrules and chondrule fragments spanning 0.2-4.7 mm diameters after 243 AFT cycles over 103.3 h. Further FT experiments on a basalt analog showed that the time required for freezing and thawing the same number of cycles can be reduced by a factor of ∼4.

  9. Spin-freezing perspective on cuprates

    Science.gov (United States)

    Werner, Philipp; Hoshino, Shintaro; Shinaoka, Hiroshi

    2016-12-01

    The high-temperature superconducting state in cuprates appears if charge carriers are doped into a Mott-insulating parent compound. An unresolved puzzle is the unconventional nature of the normal state above the superconducting dome and its connection to the superconducting instability. At weak hole doping, a "pseudogap" metal state with signatures of time-reversal symmetry breaking is observed, which near-optimal doping changes into a "strange metal" with non-Fermi-liquid properties. Qualitatively similar phase diagrams are found in multiorbital systems, such as pnictides, where the unconventional metal states arise from a Hund-coupling-induced spin freezing. Here, we show that the relevant model for cuprates, the single-orbital Hubbard model on the square lattice, can be mapped onto an effective multiorbital problem with strong ferromagnetic Hund coupling. The spin-freezing physics of this multiorbital system explains the phenomenology of cuprates, including the pseudogap, the strange metal, and the d -wave superconducting instability. Our analysis suggests that spin/orbital freezing is the universal mechanism which controls the properties of unconventional superconductors.

  10. Defining local food

    DEFF Research Database (Denmark)

    Eriksen, Safania Normann

    2013-01-01

    Despite evolving local food research, there is no consistent definition of “local food.” Various understandings are utilized, which have resulted in a diverse landscape of meaning. The main purpose of this paper is to examine how researchers within the local food systems literature define local...... food, and how these definitions can be used as a starting point to identify a new taxonomy of local food based on three domains of proximity....

  11. Improvement of dissolution property of poorly water-soluble drug by supercritical freeze granulation.

    Science.gov (United States)

    Sonoda, Ryoichi; Hara, Yuko; Iwasaki, Tomohiro; Watano, Satoru

    2009-10-01

    The dissolution property of the poorly water-soluble drug, flurbiprofen (FP) was improved by a novel supercritical freeze granulation using supercritical carbon dioxide. Supercritical freeze granulation was defined as a production method of the granulated substances by using the dry ice to generate intentionally for the rapid atomization of the supercritical carbon dioxide to the atmospheric pressure. This process utilized a rapid expansion of supercritical solutions (RESS) process with the mixture of the drug and lactose. In the supercritical freeze granulation, needle-like FP fine particles were obtained which adhered to the surface of lactose particles, which did not dissolve in supercritical carbon dioxide. The number of FP particles that adhered to the surface of particles decreased with an increase in the ratio of lactose added, leading to markedly improve the dissolution rate. This improvement was caused not only by the increase in the specific surface area but also the improvement of the dispersibility of FP in water. It is thus concluded that the supercritical freeze granulation is a useful technique to improve the dissolution property of the poorly water-soluble flurbiprofen.

  12. 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

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

    Science.gov (United States)

    Moffitt, Christine M.; James, Christopher A.

    2012-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-11-01

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

  15. 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)

  16. Recent Developments in Smart Freezing Technology Applied to Fresh Foods.

    Science.gov (United States)

    Xu, Ji-Cheng; Zhang, Min; Mujumdar, Arun S; Adhikari, Benu

    2015-10-13

    Due to the increased awareness of consumers in sensorial and nutritional quality of frozen foods, the freezing technology has to seek new and innovative technologies for better retaining the fresh-like quality. In this article, we reviewed the recent developments in smart freezing technology applied to fresh foods. The application of these intelligent technologies and the associated underpinning concepts has greatly improved the quality of frozen foods and the freezing efficiency. These technologies are able to automatically collect the information in-line during freezing and help control the freezing process better. Smart freezing technology includes new and intelligent technologies and concepts applied to the pretreatment of the frozen product, freezing processes, cold chain logistics as well as warehouse management. These technologies enable real-time monitoring of quality during freezing process and help improve product quality and freezing efficiency. We also provided a brief overview of several sensing technologies used to achieve automatic control of individual steps of freezing process. These sensing technologies included computer vision, electronic nose, electronic tongue, digital simulation, confocal laser, near infrared spectroscopy, nuclear magnetic resonance technology and ultrasound. Understanding of the mechanism of these new technologies will be helpful for applying them to improve the quality of frozen foods.

  17. Analytic-numerical method of determining the freezing front location

    Directory of Open Access Journals (Sweden)

    R. Grzymkowski

    2011-07-01

    Full Text Available Mathematical modeling of thermal processes combined with the reversible phase transitions of type: solid phase – liquid phase leads to formulation of the parabolic boundary problems with the moving boundary. Solution of such defined problem requires, most often, to use sophisticated numerical techniques and far advanced mathematical tools. Excellent illustration of the complexity of considered problems, as well as of the variety of approaches used for finding their solutions, gives the papers [1-4]. In the current paper, the authors present the, especially attractive from the engineer point of view, analytic-numerical method for finding the approximate solution of selected class of problems which can be reduced to the one-phase solidification problem of a plate with the unknown a priori, varying in time boundary of the region in which the solution is sought. Proposed method is based on the known formalism of initial expansion of the sought function describing the temperature field into the power series, some coefficients of which are determined with the aid of boundary conditions, and on the approximation of the function defining the location of freezing front with the broken line, parameters of which are numerically determined.

  18. Software-Defined Cluster

    Institute of Scientific and Technical Information of China (English)

    聂华; 杨晓君; 刘淘英

    2015-01-01

    The cluster architecture has played an important role in high-end computing for the past 20 years. With the advent of Internet services, big data, and cloud computing, traditional clusters face three challenges: 1) providing flexible system balance among computing, memory, and I/O capabilities;2) reducing resource pooling overheads;and 3) addressing low performance-power efficiency. This position paper proposes a software-defined cluster (SDC) architecture to deal with these challenges. The SDC architecture inherits two features of traditional cluster: its architecture is multicomputer and it has loosely-coupled interconnect. SDC provides two new mechanisms: global I/O space (GIO) and hardware-supported native access (HNA) to remote devices. Application software can define a virtual cluster best suited to its needs from resources pools provided by a physical cluster, and traditional cluster ecosystems need no modification. We also discuss a prototype design and implementation of a 32-processor cloud server utilizing the SDC architecture.

  19. Implementing Software Defined Radio

    CERN Document Server

    Grayver, Eugene

    2013-01-01

    Software Defined Radio makes wireless communications easier, more efficient, and more reliable. This book bridges the gap between academic research and practical implementation. When beginning a project, practicing engineers, technical managers, and graduate students can save countless hours by considering the concepts presented in these pages. The author covers the myriad options and trade-offs available when selecting an appropriate hardware architecture. As demonstrated here, the choice between hardware- and software-centric architecture can mean the difference between meeting an aggressive schedule and bogging down in endless design iterations. Because of the author’s experience overseeing dozens of failed and successful developments, he is able to present many real-life examples. Some of the key concepts covered are: Choosing the right architecture for the market – laboratory, military, or commercial Hardware platforms – FPGAs, GPPs, specialized and hybrid devices Standardization efforts to ens...

  20. Defining cyber warfare

    Directory of Open Access Journals (Sweden)

    Dragan D. Mladenović

    2012-04-01

    Full Text Available Cyber conflicts represent a new kind of warfare that is technologically developing very rapidly. Such development results in more frequent and more intensive cyber attacks undertaken by states against adversary targets, with a wide range of diverse operations, from information operations to physical destruction of targets. Nevertheless, cyber warfare is waged through the application of the same means, techniques and methods as those used in cyber criminal, terrorism and intelligence activities. Moreover, it has a very specific nature that enables states to covertly initiate attacks against their adversaries. The starting point in defining doctrines, procedures and standards in the area of cyber warfare is determining its true nature. In this paper, a contribution to this effort was made through the analysis of the existing state doctrines and international practice in the area of cyber warfare towards the determination of its nationally acceptable definition.

  1. Freezing of water saturated in aluminum wool mats

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, M.; Onodera, T.; Komatsu, Y.; Tago, M. [Akita University, Department of Mechanical Engineering, Faculty of Engineering and Resource Science, Akita (Japan); Beer, H. [Technische Universitat Darmstadt, Institut fur Technische Thermodynamik, Darmstadt (Germany)

    2008-05-15

    This paper is concerned with the freezing of water saturated in aluminum wool mats (AWM) around a cooling pipe. Two arrangements of AWM around the pipe are considered, i.e. a disk-type and a roll-type. Freezing mass M(kg/m{sup 2}) in the disk type for a porosity {epsilon} = 0.95, indicates to be two times larger compared with that without AWM (i.e. {epsilon} = 1) at the freezing time t = 180 min. Even a small AWM volume fraction enhances considerably freezing of water in the disk type. However, freezing enhancement in the roll type is small compared with that of the disk type. Numerical calculation predicts well freezing at the disk type arrangement by using an anisotropy model for the effective thermal conductivity of ice/water saturated AWM, however, poor predictions for the roll type arrangement. (orig.)

  2. Freezing of water saturated in aluminum wool mats

    Science.gov (United States)

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

    2008-05-01

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

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

    Science.gov (United States)

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

    2015-10-13

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

  4. 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.

  5. Anisotropic silk fibroin/gelatin scaffolds from unidirectional freezing

    Energy Technology Data Exchange (ETDEWEB)

    Asuncion, Maria Christine Tankeh, E-mail: christine.asuncion@u.nus.edu [National University of Singapore, Department of Biomedical Engineering (Singapore); Goh, James Cho-Hong [National University of Singapore, Department of Biomedical Engineering (Singapore); National University of Singapore, Department of Orthopedic Surgery (Singapore); Toh, Siew-Lok [National University of Singapore, Department of Biomedical Engineering (Singapore); National University of Singapore, Department of Mechanical Engineering (Singapore)

    2016-10-01

    Recent studies have underlined the importance of matching scaffold properties to the biological milieu. Tissue, and thus scaffold, anisotropy is one such property that is important yet sometimes overlooked. Methods that have been used to achieve anisotropic scaffolds present challenges such as complicated fabrication steps, harsh processing conditions and toxic chemicals involved. In this study, unidirectional freezing was employed to fabricate anisotropic silk fibroin/gelatin scaffolds in a simple and mild manner. Morphological, mechanical, chemical and cellular compatibility properties were investigated, as well as the effect of the addition of gelatin to certain properties of the scaffold. It was shown that scaffold properties were suitable for cell proliferation and that mesenchymal stem cells were able to align themselves along the directed fibers. The fabricated scaffolds present a platform that can be used for anisotropic tissue engineering applications such as cardiac patches. - Highlights: • Silk/gelatin scaffolds with unidirectional alignment were fabricated using a simple and scalable process • Presence of gelatin in silk resulted to lesser shrinkage, better water retention and improved cell proliferation. • Mesenchymal stem cells were shown to align themselves according to the fiber alignment.

  6. How to freeze drop oscillations with powders

    Science.gov (United States)

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

    2012-11-01

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

  7. 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.

  8. 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...

  9. Gradient porous hydroxyapatite ceramics fabricated by freeze casting method

    Science.gov (United States)

    Zuo, Kai-hui; zhang, Yuan; Jiang, Dongliang; Zeng, Yu-Ping

    2011-04-01

    By controlling the cooling rates and the composition of slurries, the gradient porous hydroxyapatite ceramics are fabricated by the freeze casting method. According to the different cooling rate, the pores of HAP ceramics fabricated by gradient freeze casting are divided into three parts: one is lamellar pores, another is column pore and the last one is fine round pores. The laminated freeze casting is in favour of obtaining the gradient porous ceramics composed of different materials and the ceramics have unclear interfaces.

  10. Distribution of Vapor Pressure in the Vacuum Freeze-Drying Equipment

    Directory of Open Access Journals (Sweden)

    Shiwei Zhang

    2012-01-01

    Full Text Available In the big vacuum freeze-drying equipment, the drying rate of materials is uneven at different positions. This phenomenon can be explained by the uneven distribution of vapor pressure in chamber during the freeze-drying process. In this paper, a mathematical model is developed to describe the vapor flow in the passageways either between material plates and in the channel between plate groups. The distribution of vapor pressure along flow passageway is given. Two characteristic factors of passageways are defined to express the effects of structural and process parameters on vapor pressure distribution. The affecting factors and their actions are quantitatively discussed in detail. Two examples are calculated and analyzed. The analysis method and the conclusions are useful to estimate the difference of material drying rate at different parts in equipment and to direct the choice of structural and process parameters.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

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

    Science.gov (United States)

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

    1995-01-01

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

  17. Defining the Anthropocene

    Science.gov (United States)

    Lewis, Simon; Maslin, Mark

    2016-04-01

    Time is divided by geologists according to marked shifts in Earth's state. Recent global environmental changes suggest that Earth may have entered a new human-dominated geological epoch, the Anthropocene. Should the Anthropocene - the idea that human activity is a force acting upon the Earth system in ways that mean that Earth will be altered for millions of years - be defined as a geological time-unit at the level of an Epoch? Here we appraise the data to assess such claims, first in terms of changes to the Earth system, with particular focus on very long-lived impacts, as Epochs typically last millions of years. Can Earth really be said to be in transition from one state to another? Secondly, we then consider the formal criteria used to define geological time-units and move forward through time examining whether currently available evidence passes typical geological time-unit evidence thresholds. We suggest two time periods likely fit the criteria (1) the aftermath of the interlinking of the Old and New Worlds, which moved species across continents and ocean basins worldwide, a geologically unprecedented and permanent change, which is also the globally synchronous coolest part of the Little Ice Age (in Earth system terms), and the beginning of global trade and a new socio-economic "world system" (in historical terms), marked as a golden spike by a temporary drop in atmospheric CO2, centred on 1610 CE; and (2) the aftermath of the Second World War, when many global environmental changes accelerated and novel long-lived materials were increasingly manufactured, known as the Great Acceleration (in Earth system terms) and the beginning of the Cold War (in historical terms), marked as a golden spike by the peak in radionuclide fallout in 1964. We finish by noting that the Anthropocene debate is politically loaded, thus transparency in the presentation of evidence is essential if a formal definition of the Anthropocene is to avoid becoming a debate about bias. The

  18. Theoretical and numerical studies of crack initiation and propagation in rock masses under freezing pressure and far-field stress

    Directory of Open Access Journals (Sweden)

    Yongshui Kang

    2014-10-01

    Full Text Available Water-bearing rocks exposed to freezing temperature can be subjected to freeze–thaw cycles leading to crack initiation and propagation, which are the main causes of frost damage to rocks. Based on the Griffith theory of brittle fracture mechanics, the crack initiation criterion, propagation direction, and crack length under freezing pressure and far-field stress are analyzed. Furthermore, a calculation method is proposed for the stress intensity factor (SIF of the crack tip under non-uniformly distributed freezing pressure. The formulae for the crack/fracture propagation direction and length of the wing crack under freezing pressure are obtained, and the mechanism for coalescence of adjacent cracks is investigated. In addition, the necessary conditions for different coalescence modes of cracks are studied. Using the topology theory, a new algorithm for frost crack propagation is proposed, which has the capability to define the crack growth path and identify and update the cracked elements. A model that incorporates multiple cracks is built by ANSYS and then imported into FLAC3D. The SIFs are then calculated using a FISH procedure, and the growth path of the freezing cracks after several calculation steps is demonstrated using the new algorithm. The proposed method can be applied to rocks containing fillings such as detritus and slurry.

  19. Freeze-Drying Above the Glass Transition Temperature in Amorphous Protein Formulations While Maintaining Product Quality and Improving Process Efficiency.

    Science.gov (United States)

    Depaz, Roberto A; Pansare, Swapnil; Patel, Sajal Manubhai

    2016-01-01

    This study explored the ability to conduct primary drying during lyophilization at product temperatures above the glass transition temperature of the maximally freeze-concentrated solution (Tg′) in amorphous formulations for four proteins from three different classes. Drying above Tg′ resulted in significant reductions in lyophilization cycle time. At higher protein concentrations, formulations freeze dried above Tg′ but below the collapse temperature yielded pharmaceutically acceptable cakes. However, using an immunoglobulin G type 4 monoclonal antibody as an example, we found that as protein concentration decreased, minor extents of collapse were observed in formulations dried at higher temperatures. No other impacts to product quality, physical stability, or chemical stability were observed in this study among the different drying conditions for the different proteins. Drying amorphous formulations above Tg′, particularly high protein concentration formulations, is a viable means to achieve significant time and cost savings in freeze-drying processes.

  20. 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

  1. Effects of Freeze-Dried Vegetable Products on the Technological Process and the Quality of Dry Fermented Sausages.

    Science.gov (United States)

    Eisinaite, Viktorija; Vinauskiene, Rimante; Viskelis, Pranas; Leskauskaite, Daiva

    2016-09-01

    The aim of this study was to compare the chemical composition of freeze-dried vegetable powders: celery, celery juice, parsnip and leek. The effect of different freeze-dried vegetables onto the ripening process and the properties of dry fermented sausages was also evaluated. Vegetable products significantly (p fermentation and ripening process of dry fermented sausages. In addition, the color parameters for sausages with the added lyophilised celery products were considerable (p sausages made with lyophilised celery juice were characterised by higher lightness and lower hardness than those made with the addition of other vegetable products and control. Freeze-dried celery, celery juice, parsnip and leek have some potential for the usage as a functional ingredient or as a source for indirect addition of nitrate in the production of fermented sausages.

  2. Asset Freezing: Smart Sanction or Criminal Charge?

    Directory of Open Access Journals (Sweden)

    Wouter de Zanger

    2011-02-01

    Full Text Available In this article the question is asked whether asset freezing can be qualified as a criminal charge within the meaning of Article6 ECHR and if yes, what effects this qualification may have on the legislative framework on so called smart sanctions. Byanalysing Community and EU law and case law of the European Court of Human Rights, General Court of Instance andCourt of Justice of the European Communities the authors give an overview of the notion and possible qualification of assetfreezing as a criminal charge. The article further focusses on the consequenses of qualifying asset freezing as a criminal chargeunder ECHR and EC/EU law and concludes by answering the aforementioned question.This article is a rewrite of a research paper written under supervision of prof. dr. J.A.E. Vervaele and prof. dr. C.H. Brants(Willem Pompe Institute for Criminal Law and Criminology, Utrecht University School of Law, whom the authors wouldlike to thank for their useful comments and supervision.

  3. Spray freeze drying of YSZ nanopowder

    Science.gov (United States)

    Raghupathy, Bala P. C.; Binner, J. G. P.

    2012-07-01

    Spray freeze drying of yttria stabilised zirconia nanopowders with a primary particle size of 16 nm has been undertaken using different solids content starting suspensions, with the effect of the latter on the flowability and crushability of the granules being investigated. The flowability and fill density of the granules increased with an increase in the solid content of the starting suspension, whilst the crushability decreased. The powder flowability, measured using a Hall flowmeter and model shoe-die filling tests, showed that the flowability of otherwise poorly flowable nanopowders can be improved to match that of the commercial spray dried submicron powder. The 5.5 vol.% solid content based suspension yielded soft agglomerates whilst a 28 vol.% solid content suspension formed hard agglomerates on spray freeze drying; the granule relics were visible in the fracture surface of the die pressed green compact in the latter case. The increase in granule strength is explained by the reduction in inter-particle distance based on the theories developed by Rumpf and Kendall. The flaw sizes computed using the Kendall model are comparable with those seen in the micrographs of the granule. With an optimum solid content, it is possible to have a granulated nanopowder with reasonable flowability and compactability resulting in homogeneous green bodies with 54 % of theoretical density.

  4. 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

  5. Estimating the impact of single and multiple freezes on video quality

    NARCIS (Netherlands)

    Van Kester, S.; Xiao, T.; Kooij, R.E.; Brunnstrom, K.; Ahmed, O.K.

    2011-01-01

    This paper studies the impact of freezing of video on quality as experienced by users. Two types of freezes are investigated. First a freeze where the image pauses, so no frames were lost (frame halt). In the second type of freeze, the image freezes and skips that part of the video (frame drop). Mea

  6. Kinetics of early in vitro development of bovine in vivo- and in vitro-derived zygotes produced and/or cultured in chemically defined or serum-containing media

    DEFF Research Database (Denmark)

    Holm, P; Booth, P J; Callesen, H

    2002-01-01

    at first cleavage (defined serum: 20-22% versus in vivo-derived: 8 P cell cycles of in vivo-derived zygotes were 1-5 h shorter compared with those of in vitro-derived zygotes cultured under similar conditions (P ... development was affected by serum during IVM-IVF and culture. The first and fourth cell cycles were prolonged by 4-5 h in the absence of serum during IVM-IVF, whereas the presence of serum during culture decreased the duration of the fourth cell cycle and triggered premature blastulation. The results......The kinetics of the in vitro development of early embryos from bovine zygotes derived in vitro and in vitro were compared, investigating the effect of serum during in vitro maturation and fertilization (IVM-IVF) and in culture. Zygotes were collected from superovulated heifers or produced in vitro...

  7. On defining dietary fibre.

    Science.gov (United States)

    DeVries, Jonathan W

    2003-02-01

    Establishing a definition for dietary fibre has historically been a balance between nutrition knowledge and analytical method capabilities. While the most widely accepted physiologically-based definitions have generally been accurate in defining the dietary fibre in foods, scientists and regulators have tended, in practice, to rely on analytical procedures as the definitional basis in fact. As a result, incongruities between theory and practice have resulted in confusion regarding the components that make up dietary fibre. In November 1998 the president of the American Association of Cereal Chemists (AACC) appointed an expert scientific review committee and charged it with the task of reviewing and, if necessary, updating the definition of dietary fibre. The committee was further charged with assessing the state of analytical methodology and making recommendations relevant to the updated definition. After due deliberation, an updated definition of dietary fibre was delivered to the AACC Board of Directors for consideration and adoption (Anon, 2000; Jones 2000b). The updated definition includes the same food components as the historical working definition used for approximately 30 years (a very important point, considering that the majority of the research of the past 30 years delineating the positive health effects of dietary fibre is based on that working definition). However, the updated definition more clearly delineates the make-up of dietary fibre and its physiological functionality. As a result, relatively few changes will be necessary in analytical methodology. Current methodologies, in particular AACC-approved method of analysis 32-05 (Grami, 2000), Association of Official Analytical Chemists' official method of analysis 985.29 (Horwitz, 2000a) or AACC 32-07 (Grami, 2000) Association of Official Analytical Chemists 991.43 (Horwitz, 2000a) will continue to be sufficient and used for most foods. A small number of additional methods will be necessary to

  8. Durability of Concrete Subjected to the Combined Actions of Flexural Stress,Freeze-thaw Cycles and Bittern Solutions

    Institute of Scientific and Technical Information of China (English)

    YU Hongfa; SUN Wei; ZHANG Yunsheng; GUO Liping; LI Meidan

    2008-01-01

    Freeze-thaw durabilities of three types of concretes-normal portland cement concrete (OPC),high strength concrete (HSC) and steel fiber reinforced high strength concrete (SFRHSC)were systemically investigated under the attacks of chemical solution,and combination of external flexural stress and chemical solution.Four kinds of bitterns from salt lakes in Sinkiang,Qinghai,Inner Mongolia and Tibet provinces of China were used as chemical attack solutions.The relative dynamic modulus (RDM) was used as an index for evaluating the damage degree during the course of chemical attack and stress corrosion.The experimental results show that the freeze-thaw durability of concrete is visibly reduced in the present of the flexural stress,i e,stress accelerates the damage process.In order to quantify the stress accelerated effect,a stress accelerating coefficient was proposed.The stress accelerating coefficient is closely related with the types of bitterns and the numbers of freeze-thaw cycles is.The more numbers of freeze-thaw cycles is,the greater the stress accelerating coefficient for various concretes will be.In addition,there also exists a critical ratio of external stress to the maximum flexural stress.If the stress ratio exceeds the critical one,the freeze-thaw durability of various concretes will be greatly decreased compared to the responding concretes without applied stress.The critical stress ratio of OPC,HSC and SFRHSC is 0.30,0.40 and 0.40,respectively,indicating that HSC and SFRHSC have advantages over OPC and are suitable to use in the bittern erosion regions.

  9. Effects of freeze-thaw on characteristics of new KMP binder stabilized Zn- and Pb-contaminated soils.

    Science.gov (United States)

    Wei, Ming-Li; Du, Yan-Jun; Reddy, Krishna R; Wu, Hao-Liang

    2015-12-01

    For viable and sustainable reuse of solidified/stabilized heavy metal-contaminated soils as roadway subgrade materials, long-term durability of these soils should be ensured. A new binder, KMP, has been developed for solidifying/stabilizing soils contaminated with high concentrations of heavy metals. However, the effects of long-term extreme weather conditions including freeze and thaw on the leachability and strength of the KMP stabilized contaminated soils have not been investigated. This study presents a systematic investigation on the impacts of freeze-thaw cycle on leachability, strength, and microstructural characteristics of the KMP stabilized soils spiked with Zn and Pb individually and together. For comparison purpose, Portland cement is also tested as a conventional binder. Several series of tests are conducted including the toxicity characteristic leaching procedure (TCLP), modified European Community Bureau of Reference (BCR) sequential extraction procedure, unconfined compression test (UCT), and mercury intrusion porosimetry (MIP). The results demonstrate that the freeze-thaw cycles have much less impact on the leachability and strength of the KMP stabilized soils as compared to the PC stabilized soils. After the freeze-thaw cycle tests, the KMP stabilized soils display much lower leachability, mass loss, and strength loss. These results are assessed based on the chemical speciation of Zn and Pb, and pore size distribution of the soils. Overall, this study demonstrates that the KMP stabilized heavy metal-contaminated soils perform well under the freeze-thaw conditions.

  10. Formation of highly porous aerosol particles by atmospheric freeze-drying in ice clouds.

    Science.gov (United States)

    Adler, Gabriela; Koop, Thomas; Haspel, Carynelisa; Taraniuk, Ilya; Moise, Tamar; Koren, Ilan; Heiblum, Reuven H; Rudich, Yinon

    2013-12-17

    The cycling of atmospheric aerosols through clouds can change their chemical and physical properties and thus modify how aerosols affect cloud microphysics and, subsequently, precipitation and climate. Current knowledge about aerosol processing by clouds is rather limited to chemical reactions within water droplets in warm low-altitude clouds. However, in cold high-altitude cirrus clouds and anvils of high convective clouds in the tropics and midlatitudes, humidified aerosols freeze to form ice, which upon exposure to subsaturation conditions with respect to ice can sublimate, leaving behind residual modified aerosols. This freeze-drying process can occur in various types of clouds. Here we simulate an atmospheric freeze-drying cycle of aerosols in laboratory experiments using proxies for atmospheric aerosols. We find that aerosols that contain organic material that undergo such a process can form highly porous aerosol particles with a larger diameter and a lower density than the initial homogeneous aerosol. We attribute this morphology change to phase separation upon freezing followed by a glass transition of the organic material that can preserve a porous structure after ice sublimation. A porous structure may explain the previously observed enhancement in ice nucleation efficiency of glassy organic particles. We find that highly porous aerosol particles scatter solar light less efficiently than nonporous aerosol particles. Using a combination of satellite and radiosonde data, we show that highly porous aerosol formation can readily occur in highly convective clouds, which are widespread in the tropics and midlatitudes. These observations may have implications for subsequent cloud formation cycles and aerosol albedo near cloud edges.

  11. Indication of a Differential Freeze-out in Proton-Proton and Heavy-Ion Collisions at RHIC and LHC energies

    CERN Document Server

    Thakur, Dhananjaya; Garg, Prakhar; Sahoo, Raghunath; Cleymans, Jean

    2016-01-01

    The experimental data from the RHIC and LHC experiments of invariant pT spectra in A+A and p + p collisions are analysed with Tsallis distributions in different approaches. The information about the freeze-out surface in terms of freeze-out volume, temperature, chemical potential and radial flow velocity for different particle species are obtained. Further, these parameters are studied as a function of the mass of the secondary particles. A mass-dependent differential freeze-out is observed which does not seem to distinguish between particles and their antiparticles. Further a mass-hierarchy in the radial flow is observed, meaning heavier particles suffer lower radial flow. Tsallis distribution function at finite chemical potential is used to study the mass dependence of chemical potential. The peripheral heavy-ion and proton-proton collisions at the same energies seem to be equivalent in terms of the extracted thermodynamic parameters.

  12. References on Compression of Freeze-Dried Foods

    Science.gov (United States)

    1978-08-01

    fully freeze-dried materials are moistened by resorption prior to compression. Compression in vacuum was successfully demonstrated. Similarly, freeze...room temperature). Bars were evaluated for cohesiveness, dimensional stability under pressure, ease of shear by the incisors and subsequent...under pressure, ease of shear by the incisors and subsequent mastication. Observations on free fatty acids, peroxide value and browning (fluorescence

  13. DOES GLUTATHIONE PLAY A ROLE IN FREEZING TOLERANCE OF PLANTS

    NARCIS (Netherlands)

    Stuiver, C.E.E.; De Kok, Luit J.; Kuiper, P.J.C.

    1992-01-01

    During low temperature hardening enhanced levels of glutathione (GSH) are generally observed in plant shoots and are often related to the development of freezing tolerance. The present communication shows that there is no direct relation between an increased GSH content and freezing tolerance of lea

  14. Determination of Freeze-out Conditions from Lattice QCD Calculations

    CERN Document Server

    Karsch, Frithjof

    2012-01-01

    Freeze-out conditions in Heavy Ion Collisions are generally determined by comparing experimental results for ratios of particle yields with theoretical predictions based on applications of the Hadron Resonance Gas model. We discuss here how this model dependent determination of freeze-out parameters may eventually be replaced by theoretical predictions based on equilibrium QCD thermodynamics.

  15. Cooling system with automated seasonal freeze protection

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-24

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

  16. Cooling method with automated seasonal freeze protection

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-31

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

  17. Universality in freezing of an asymmetric drop

    Science.gov (United States)

    Ismail, Md Farhad; Waghmare, Prashant R.

    2016-12-01

    We present the evidence of universality in conical tip formation during the freezing of arbitrary-shaped sessile droplets. The focus is to demonstrate the relationship between this universality and the liquid drop shape. We observe that, in the case of asymmetric drops, this universal shape is achieved when the tip reconfigures by changing its location, which subsequently alters the frozen drop shape. The proposed "two-triangle" model quantifies the change in the tip configuration as a function of the asymmetry of the drop that shows a good agreement with the experimental evidence. Finally, based on the experimental and theoretical exercise, we propose the scaling dependence between the variations in the tip configuration and the asymmetry of the drop.

  18. Freezing resistance of high iron phoasphoaluminate cement

    Science.gov (United States)

    Zhang, S. X.; Lu, L. C.; Wang, S. D.; Zhao, P. Q.; Gong, C. C.

    2017-03-01

    The influence of freeze-thaw cycle on the mechanical properties of high iron phoasphoaluminate cement was investigated in the present study. The visual examination was conducted to evaluate the surface damage. The deterioration considering the weight loss, modulus loss of relative dynamic elastic and strength loss of mortar were also investigated. The morphology of hydration products were analysed by SEM. Compared with ordinary Portland cement and sulphoaluminate cement, the frost resistance of high iron phosphoraluminate cement is better. Hydration products of high iron phoasphoaluminate cement contain sheet crystals, and a lot of gel form a dense three-dimensional network structure, which results in a lower porosity. Different from ordinary Portland cement, the hydration product of high iron phoasphoaluminate cement does not contain Ca(OH)2, and low alkalinity reduces its osmotic pressure. The lower porosity and osmotic pressure are the two main reasons which causes in the higher frost resistance of high iron phoasphoaluminate cement.

  19. Hot water can freeze faster than cold?!?

    CERN Document Server

    Jeng, M

    2005-01-01

    We review the Mpemba effect, where intially hot water freezes faster than initially cold water. While the effect appears impossible at first sight, it has been seen in numerous experiments, was reported on by Aristotle, Francis Bacon, and Descartes, and has been well-known as folklore around the world. It has a rich and fascinating history, which culminates in the dramatic story of the secondary school student, Erasto Mpemba, who reintroduced the effect to the twentieth century scientific community. The phenomenon, while simple to describe, is deceptively complex, and illustrates numerous important issues about the scientific method: the role of skepticism in scientific inquiry, the influence of theory on experiment and observation, the need for precision in the statement of a scientific hypothesis, and the nature of falsifiability. We survey proposed theoretical mechanisms for the Mpemba effect, and the results of modern experiments on the phenomenon. Studies of the observation that hot water pipes are more ...

  20. 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.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

    Al-Hussein, Anas; Gieseler, Henning

    2015-01-01

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

  4. Augmenting Lagoon Process Using Reactivated Freeze-dried Biogranules.

    Science.gov (United States)

    Pishgar, Roya; Hamza, Rania Ahmed; Tay, Joo Hwa

    2017-02-24

    This study investigated the feasibility of using freeze-dried biogranules in lagoon basins. The effect of different operational conditions on treatment performance and detention time of granule-based lagoons was examined in a series of laboratory-scale batch studies. Optimal granule dosage was 0.1 g/L under anaerobic condition, resulting in 80-94% removal of 1000 mg/L chemical oxygen demand (COD) in 7-10 days. Under aerobic condition, granule dosage of 0.2 g/L achieved the best result for identical COD concentration. However, adequate amount of nutrients (optimal COD/N/P ratio of 100/13/0.8) should be supplied to encourage the growth of aerobic species. At optimal COD/N/P ratio, aerobic treatment interval significantly reduced to 2-3 days with corresponding COD removal efficiency of 88-92%. Inhibition of high concentrations of COD (5000 mg/L) and ammonia (480 mg/L NH4-N) was observed on microbial activity and treatment capacity of the biogranules. Mixing was a crucial measure to overcome mass transfer limitation. Onetime inoculation of lagoon with fresh granules was the best approach to achieve a satisfactory treatment efficiency. This study suggested that utilization of the biogranules is a feasible and sustainable technique for augmenting lagoon plants in terms of improved effluent quality and reduced retention time. Graphical Abstract ᅟ.

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

    Science.gov (United States)

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

    2014-02-18

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

  6. Effects of freezing/thawing on motile sperm subpopulations of boar and donkey ejaculates.

    Science.gov (United States)

    Flores, E; Taberner, E; Rivera, M M; Peña, A; Rigau, T; Miró, J; Rodríguez-Gil, J E

    2008-10-01

    The main aim of this study is to assess the influence of freeze/thawing on motile sperm subpopulations in ejaculates from two phylogenetically different mammalian species, boar and donkey. Our results indicate that, whereas boar and donkey sperm respond very differently in their mean motion characteristics to freezing/thawing, this process did not change the existence of a 4-subpopulations structure in the ejaculates in either species when these subpopulations were defined by taking values of curvilinear velocity (VCL) as reference. Moreover, the freezing/thawing-linked changes in mean sperm-motion characteristics in both boar and donkey semen were especially due to changes in the proportion among each concrete subpopulation. In this way, the freezing/thawing-induced mean increase in motion characteristics observed in boar sperm was a result of the decrease in the percentage of sperm in Subpopulation 1 (from 53.9%+/-4.7% to 31.2%+/-3.9% after thawing) and a concomitant increase of sperm from Subpopulations 3 (from 13.3%+/-2.5% to 32.6%+/-3.9% after thawing) and 4 (from 3.4%+/-0.9% to 8.0%+/-1.1% after thawing). On the contrary, changes in mean motility of frozen/thawed donkey sperm were linked to an increase in the percentage of sperm in Subpopulation 1 (from 31.5%+/-4.3% to 58.8%+/-4.9% after thawing) and a concomitant decrease of sperm from Subpopulations 3 (from 32.4%+/-3.2% to 6.6%+/-1.8% after thawing) and 4 (from 12.2%+/-2.5% to 7.3%+/-1.9% after thawing). In conclusion, our results seem to indicate that motility changes induced by the freezing/thawing protocol are linked to concomitant changes in both the specific parameters and, more importantly, to the specific percentage of each of the motile sperm subpopulations. These changes did not affect the overall proportion of motile sperm present in both boar and donkey, which is conserved despite the detrimental effect caused by freezing/thawing in both species. Finally, the presence of some kind of motile sperm

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

    Science.gov (United States)

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

    2016-11-01

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

  8. New freeze-drying method for LiFePO 4 synthesis

    Science.gov (United States)

    Palomares, Verónica; Goñi, Aintzane; Muro, Izaskun Gil de; de Meatza, Iratxe; Bengoechea, Miguel; Miguel, Oscar; Rojo, Teófilo

    The freeze-drying method is proposed as an effective synthesis process for the obtaining of LiFePO 4/C composites. The citric acid is used as a complexing agent and carbon source. After the low temperature annealing, the freeze-dried solution leads to a homogeneous carbon covered LiFePO 4 sample. The chemical characterization of the material included ICP and elemental analysis, infrared spectroscopy, X-ray diffraction, magnetic measurements and thermal analysis. SEM and TEM microscopies indicate an aggregate morphology with tiny particles of lithium iron phosphate inside a carbon matrix. Impedance spectroscopy showed a 8.0 × 10 -7 S cm -1 conductivity value. Cyclic voltammetry graphics displayed the two peaks corresponding to the Fe(II)/Fe(III) reaction and demonstrated the good reversibility of the material. The specific capacity value obtained at C/40 rate was 164 mAh g -1, with a slight decrease on greater C-rates reaching 146 mAh g -1 at C/1. The capacity retention study has evidenced good properties, with retention over 97% of the maximum values in the first 50 cycles, which allows an effective performance of the freeze-dried sample as cathodic material in lithium-ion batteries.

  9. Adsorption and Desorption of Ammonium in Wetland Soils Subject to Freeze-Thaw Cycles

    Institute of Scientific and Technical Information of China (English)

    YU Xiao-Fei; ZHANG Yu-Xia; ZOU Yuan-Chun; ZHAO Hong-Mei; LU Xian-Guo; WANG Guo-Ping

    2011-01-01

    Nitrogen (N) cycling in boreal peatland ecosystems may be influenced in important ways by freeze-thaw cycles (FTCs). Adsorption and desorption of ammonium ions (NH4+) were examined in a controlled laboratory experiment for soils sampled from palustrine wetland, riverine wetland, and farmland reclaimed from natural wetland in response to the number of FTCs. The results indicate that freeze-thaw significantly increased the adsorption capacity of NH4+ and reduced the desorption potential of NH4+ in the wetland soils. There were significant differences in the NH4+ adsorption amount between the soils with and without freeze-thaw treatment.The adsorption amount of NH4+ increased with increasing FTCs. The palustrine wetland soil had a greater adsorption capacity and a weaker desorption potential of NH4+ than the riverine wetland soil because of the significantly higher clay content and cation exchange capacity (CEC) of the riverine wetland soil. Because of the altered soil physical and chemical properties and hydroperiods, the adsorption capacity of NH4+ was smaller in the farmland soil than in the wetland soils, while the desorption potential of the farmland soil was higher than that of the wetland soils. Thus, wetland reclamation would decrease adsorption capacity and increase desorption potential of NH4+, which could result in N loss from the farmland soil. FTCs might mitigate N loss from soils and reduce the risk of water pollution in downstream ecosystems.

  10. Experimental investigation of homogeneous freezing of sulphuric acid particles in the aerosol chamber AIDA

    Directory of Open Access Journals (Sweden)

    O. Möhler

    2002-10-01

    Full Text Available The homogeneous freezing of supercooled H2SO4/H2O solution droplets was investigated in the aerosol chamber AIDA (Aerosol Interactions and Dynamics in the Atmosphere of Forschungszentrum Karlsruhe. 24 freezing experiments were performed at temperatures between 194 and 235 K with aerosol particles in the diameter range 0.05 to 1 µm. Individual experiments started at homogeneous temperatures and ice saturation ratios between 0.85 and 0.95. Cloud cooling rates up to -2.8 K/min were simulated dynamically in the chamber by expansion cooling using a mechanical pump. Depending on the cooling rate and starting temperature, freezing threshold relative humidities were exceeded after expansion time periods between about 1 and 10 min. The onset of ice formation was measured with three independent methods showing good agreement among each other. Ice saturation ratios measured at the onset of ice formation increased from about 1.4 at 231 K to about 1.75 at 189 K. The experimental data set including thermodynamic parameters as well as physical and chemical aerosol analysis provides a good basis for microphysical model applications.

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

    Science.gov (United States)

    Henson, Cynthia A; Duke, Stanley H; Livingston, David P

    2014-01-01

    Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L.) during a fourteen day time-course after freezing. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after freezing. In contrast, sugar and sugar related metabolites were little changed by freezing, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after freezing were similar to those observed in cold acclimation whereas most changes in sugar pools after freezing were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants.

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

    Directory of Open Access Journals (Sweden)

    Cynthia A Henson

    Full Text Available Extensive research has been conducted on cold acclimation and freezing tolerance of fall-sown cereal plants due to their economic importance; however, little has been reported on the biochemical changes occurring over time after the freezing conditions are replaced by conditions favorable for recovery and growth such as would occur during spring. In this study, GC-MS was used to detect metabolic changes in the overwintering crown tissue of oat (Avena sativa L. during a fourteen day time-course after freezing. Metabolomic analysis revealed increases in most amino acids, particularly proline, 5-oxoproline and arginine, which increased greatly in crowns that were frozen compared to controls and correlated very significantly with days after freezing. In contrast, sugar and sugar related metabolites were little changed by freezing, except sucrose and fructose which decreased dramatically. In frozen tissue all TCA cycle metabolites, especially citrate and malate, decreased in relation to unfrozen tissue. Alterations in some amino acid pools after freezing were similar to those observed in cold acclimation whereas most changes in sugar pools after freezing were not. These similarities and differences suggest that there are common as well as unique genetic mechanisms between these two environmental conditions that are crucial to the winter survival of plants.

  13. Sucrose Diffusion in Decellularized Heart Valves for Freeze-Drying.

    Science.gov (United States)

    Wang, Shangping; Oldenhof, Harriëtte; Goecke, Tobias; Ramm, Robert; Harder, Michael; Haverich, Axel; Hilfiker, Andres; Wolkers, Willem Frederik

    2015-09-01

    Decellularized heart valves can be used as starter matrix implants for heart valve replacement therapies in terms of guided tissue regeneration. Decellularized matrices ideally need to be long-term storable to assure off-the-shelf availability. Freeze-drying is an attractive preservation method, allowing storage at room temperature in a dried state. However, the two inherent processing steps, freezing and drying, can cause severe damage to extracellular matrix (ECM) proteins and the overall tissue histoarchitecture and thus impair biomechanical characteristics of resulting matrices. Freeze-drying therefore requires a lyoprotective agent that stabilizes endogenous structural proteins during both substeps and that forms a protective glassy state at room temperature. To estimate incubation times needed to infiltrate decellularized heart valves with the lyoprotectant sucrose, temperature-dependent diffusion studies were done using Fourier transform infrared spectroscopy. Glycerol, a cryoprotective agent, was studied for comparison. Diffusion of both protectants was found to exhibit Arrhenius behavior. The activation energies of sucrose and glycerol diffusion were found to be 15.9 and 37.7 kJ·mol(-1), respectively. It was estimated that 4 h of incubation at 37°C is sufficient to infiltrate heart valves with sucrose before freeze-drying. Application of a 5% sucrose solution was shown to stabilize acellular valve scaffolds during freeze-drying. Such freeze-dried tissues, however, displayed pores, which were attributed to ice crystal damage, whereas vacuum-dried scaffolds in comparison revealed no pores after drying and rehydration. Exposure to a hygroscopic sucrose solution (80%) before freeze-drying was shown to be an effective method to diminish pore formation in freeze-dried ECMs: matrix structures closely resembled those of control samples that were not freeze-dried. Heart valve matrices were shown to be in a glassy state after drying, suggesting that they can

  14. Induction of iron regulated proteins during normal growth of Neisseria meningitidis in a chemically defined medium Indução das proteínas reguladas pelo ferro durante o crescimento normal de Neisseria meningitidis em meio quimicamente definido

    Directory of Open Access Journals (Sweden)

    Maria Cristina de Cunto Brandileone

    1994-08-01

    Full Text Available The expression of iron regulated proteins (IRPs in vitro has been obtained in the past by adding iron chelators to the culture after bacterial growth, in the presence of an organic iron source. We have investigated aspects concerning full expression of the meningococcal IRPs during normal growth, in defined conditions using Catlin medium, Mueller Hinton and Tryptic Soy Broth (TSB. The expression of IRPs varied between different strains with respect to Ethylenediamine Di-ortho-Hidroxy-phenyl-acetic acid (EDDA concentrations, and according to culture medium, and also between different lots of TSB. For each strain, a specific set of IRPs were expressed and higher EDDA concentrations, or addition of glucose, or use of different culture media did not resulted in a differential expression of IRPs. We were not able to grow N. meningitidis under normal growth conditions using Desferal. We looked for a good yield of outer membrane vesicles (OMVs expressing IRPs in iron-deficient Catlin medium containing EDDA and Hemin. Culture for 32 h at 30ºC after growing for 16 h at 37ºC supported good bacterial growth. Bacterial lysis was noted after additional 24 h at 30ºC. Approximately 4 times more OMVs was recoverable from a culture supernatant after 24 h at 30ºC than from the cells after 16 h at 37ºC. The IRP were as well expressed in OMVs from culture supernatant obtained after 24 h at 30ºC as from the cells after 16 h at 37ºC.A expressão das proteínas reguladas pelo ferro (IRPs, in vitro, tem sido obtida pela adição de quelantes de ferro ao meio de cultura, após o crescimento bacteriano, na presença de fonte de ferro orgânico. Neste estudo foram investigados aspectos da máxima expressão das IRPs de meningococo durante o crescimento normal, em condições de cultura definidas, utilizando-se o meio de Catlin e os caldos Mueller-Hinton e Tryptic Soja (TSB. Foram avaliadas as melhores condições para se obter vesículas de membrana externa (OMVs

  15. Numerical simulations of homogeneous freezing processes in the aerosol chamber AIDA

    Directory of Open Access Journals (Sweden)

    W. Haag

    2002-10-01

    Full Text Available The homogeneous freezing of supercooled H2SO4/H2O aerosols in an aerosol chamber is investigated with a microphysical box model using the activity parameterization of the nucleation rate by Koop et al (2000. The simulations are constrained by measurements of pressure, temperature, total water mixing ratio, and the initial aerosol size distribution, described in a companion paper Möhler et al. (2002. Model results are compared to measurements conducted in the temperature range between 194 and 235 K, with cooling rates in the range between 0.5 and 2.6 K min-1, and at air pressures between 170 and 1000 hPa. The simulations focus on the time history of relative humidity with respect to ice, aerosol size distribution, partitioning of water between gas and particle phase, onset times of freezing, freezing threshold relative humidities, aerosol chemical composition at the onset of freezing, and the number of nucleated ice crystals. The latter three parameters can directly be inferred from the experiments, the former three aid in interpreting the measurements. Sensitivity studies are carried out to address the relative importance of uncertainties of basic quantities such as temperature, H2O mixing ratio, aerosol size spectrum, and deposition coefficient of H2O molecules on ice. The ability of the numerical simulations to provide detailed explanations of the observations greatly increases confidence in attempts to model this process under real  atmospheric conditions, for instance with regard to the formation of cirrus clouds or type-II polar stratospheric clouds, provided that accurate temperature and humidity measurements are available.

  16. Numerical simulations of homogeneous freezing processes in the aerosol chamber AIDA

    Directory of Open Access Journals (Sweden)

    W. Haag

    2003-01-01

    Full Text Available The homogeneous freezing of supercooled H2SO4/H2O aerosols in an aerosol chamber is investigated with a microphysical box model using the activity parameterization of the nucleation rate by Koop et al. (2000. The simulations are constrained by measurements of pressure, temperature, total water mixing ratio, and the initial aerosol size distribution, described in a companion paper Möhler et al. (2003. Model results are compared to measurements conducted in the temperature range between 194 and 235 K, with cooling rates in the range between 0.5 and 2.6 K min-1, and at air pressures between 170 and 1000 hPa. The simulations focus on the time history of relative humidity with respect to ice, aerosol size distribution, partitioning of water between gas and particle phase, onset times of freezing, freezing threshold relative humidities, aerosol chemical composition at the onset of freezing, and the number of nucleated ice crystals. The latter four parameters can be inferred from the experiments, the former three aid in interpreting the measurements. Sensitivity studies are carried out to address the relative importance of uncertainties of basic quantities such as temperature, total H2O mixing ratio, aerosol size spectrum, and deposition coefficient of H2O molecules on ice. The ability of the numerical simulations to provide detailed explanations of the observations greatly increases confidence in attempts to model this process under real atmospheric conditions, for instance with regard to the formation of cirrus clouds or polar stratospheric ice clouds, provided that accurate temperature and humidity measurements are available.

  17. 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.

  18. 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

  19. Prototype device for converting freezing energy into mechanical work

    Energy Technology Data Exchange (ETDEWEB)

    Habeebullah, B.; Zaki, G.M.; Akyurt, M. [Fakieh Center for Applied Research, Makkah Al-Mukarramah (Saudi Arabia)

    2003-01-01

    Certain properties of ice are reviewed. The phenomenon of freezing of water is discussed, with special emphasis on the blockage and bursting of water pipes. Several concepts are discussed that are related to achieving the freezing of water, the design of the container where freezing occurs and the conversion into mechanical energy. A conceptual design is presented for one type of ice energy converter. Certain design details for this machine are provided. Initial test results are furnished for this device, which was manufactured and tested. Conclusions are drawn and recommendations are made. (author)

  20. Freeze-thaw bond properties of new-old concrete

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Using composite cubic specimens of new-old concrete, the bond splitting tensile strength and failure mechanism for the interface of new-old concrete in saturating state were explored when exposed to freeze-thaw cycling. Specimens were experienced for 0,25,50,75,100 and 125 freezing cycles. The roughness and ad hesion agent including cement paste, cement mortar and cement paste with 10 percent of UEA expanding agent were also investigated. The test results indicate that the bond splitting tensile strength decreases with increased numbers of freezing-and-thawing cycles. The roughness and adhesion agent have different effects on the bond strength.

  1. On the time required to freeze water

    Science.gov (United States)

    Espinosa, J. R.; Navarro, C.; Sanz, E.; Valeriani, C.; Vega, C.

    2016-12-01

    By using the seeding technique the nucleation rate for the formation of ice at room pressure will be estimated for the TIP4P/ICE model using longer runs and a smaller grid of temperatures than in the previous work. The growth rate of ice will be determined for TIP4P/ICE and for the mW model of water. Although TIP4P/ICE and mW have a similar melting point and melting enthalpy, they differ significantly in the dynamics of freezing. The nucleation rate of mW is lower than that of TIP4P/ICE due to its higher interfacial free energy. Experimental results for the nucleation rate of ice are between the predictions of these two models when obtained from the seeding technique, although closer to the predictions of TIP4P/ICE. The growth rate of ice for the mW model is four orders of magnitude larger than for TIP4P/ICE. Avrami's expression is used to estimate the crystallization time from the values of the nucleation and growth rates. For mW the minimum in the crystallization time is found at approximately 85 K below the melting point and its value is of about a few ns, in agreement with the results obtained from brute force simulations by Moore and Molinero. For the TIP4P/ICE the minimum is found at about 55 K below the melting point, but its value is about ten microseconds. This value is compatible with the minimum cooling rate required to avoid the formation of ice and obtaining a glass phase. The crossover from the nucleation controlled crystallization to the growth controlled crystallization will be discussed for systems of finite size. This crossover could explain the apparent discrepancy between the values of J obtained by different experimental groups for temperatures below 230 K and should be considered as an alternative hypothesis to the two previously suggested: internal pressure and/or surface freezing effects. A maximum in the compressibility was found for the TIP4P/ICE model in supercooled water. The relaxation time is much smaller than the crystallization time

  2. Comparison of the depth of tissue necrosis between double-freeze and single-freeze nitrous oxide-based cryotherapy

    Directory of Open Access Journals (Sweden)

    Akinfolarin Clement Adepiti

    2016-01-01

    Full Text Available Background: Cryotherapy is one the methods of treating cervical premalignant lesions. It is particularly suitable for low-resource countries because of it is relative cheaper, has low cost of maintenance, ease of use and that does not require electricity which is in short supply in many rural areas of developing countries where the incidence and mortality from cervical cancer is very high. In this study we compared single and double freezing on the cervices of women admitted for hysterectomy for benign conditions using Nitrous-based cryotherapy. Materials and Methods: Patients admitted for elective hysterectomy for benign gynaecological conditions were randomized into two arms. The first group had single freeze cryotherapy while the second arm received double freeze cryotherapy. The cervices were examined 24 hours later to determine the depth of tissue necrosis. Results: In this comparative study, the depth of tissue necrosis was deeper with double freeze compared with single freeze. Also in both arms, the depth of necrosis was deeper on anterior lips than on posterior lips of the cervix. Conclusion: Double freeze technique achieve more depth of tissue necrosis than single-freeze on both anterior and posterior lips of the cervix.

  3. Stochastic flux freezing and magnetic dynamo.

    Science.gov (United States)

    Eyink, Gregory L

    2011-05-01

    Magnetic flux conservation in turbulent plasmas at high magnetic Reynolds numbers is argued neither to hold in the conventional sense nor to be entirely broken, but instead to be valid in a statistical sense associated to the "spontaneous stochasticity" of Lagrangian particle trajectories. The latter phenomenon is due to the explosive separation of particles undergoing turbulent Richardson diffusion, which leads to a breakdown of Laplacian determinism for classical dynamics. Empirical evidence is presented for spontaneous stochasticity, including numerical results. A Lagrangian path-integral approach is then exploited to establish stochastic flux freezing for resistive hydromagnetic equations and to argue, based on the properties of Richardson diffusion, that flux conservation must remain stochastic at infinite magnetic Reynolds number. An important application of these results is the kinematic, fluctuation dynamo in nonhelical, incompressible turbulence at magnetic Prandtl number (Pr(m)) equal to unity. Numerical results on the Lagrangian dynamo mechanisms by a stochastic particle method demonstrate a strong similarity between the Pr(m)=1 and 0 dynamos. Stochasticity of field-line motion is an essential ingredient of both. Finally, some consequences for nonlinear magnetohydrodynamic turbulence, dynamo, and reconnection are briefly considered.

  4. Drying a tuberculosis vaccine without freezing.

    Science.gov (United States)

    Wong, Yun-Ling; Sampson, Samantha; Germishuizen, Willem Andreas; Goonesekera, Sunali; Caponetti, Giovanni; Sadoff, Jerry; Bloom, Barry R; Edwards, David

    2007-02-20

    With the increasing incidence of tuberculosis and drug resistant disease in developing countries due to HIV/AIDS, there is a need for vaccines that are more effective than the present bacillus Calmette-Guérin (BCG) vaccine. We demonstrate that BCG vaccine can be dried without traditional freezing and maintained with remarkable refrigerated and room-temperature stability for months through spray drying. Studies with a model Mycobacterium (Mycobacterium smegmatis) revealed that by removing salts and cryoprotectant (e.g., glycerol) from bacterial suspensions, the significant osmotic pressures that are normally produced on bacterial membranes through droplet drying can be reduced sufficiently to minimize loss of viability on drying by up to 2 orders of magnitude. By placing the bacteria in a matrix of leucine, high-yield, free-flowing, "vial-fillable" powders of bacteria (including M. smegmatis and M. bovis BCG) can be produced. These powders show relatively minor losses of activity after maintenance at 4 degrees C and 25 degrees C up to and beyond 4 months. Comparisons with lyophilized material prepared both with the same formulation and with a commercial formulation reveal that the spray-dried BCG has better overall viability on drying.

  5. Adaptation to seasonality and the winter freeze

    Directory of Open Access Journals (Sweden)

    Jill Christine Preston

    2013-06-01

    Full Text Available Flowering plants initially diversified during the Mesozoic era at least 140 million years ago in regions of the world where temperate seasonal environments were not encountered. Since then several cooling events resulted in the contraction of warm and wet environments and the establishment of novel temperate zones in both hemispheres. In response, less than half of modern angiosperm families have members that evolved specific adaptations to cold seasonal climates, including cold acclimation, freezing tolerance, endodormancy, and vernalization responsiveness. Despite compelling evidence for multiple independent origins, the level of genetic constraint on the evolution of adaptations to seasonal cold is not well understood. However, the recent increase in molecular genetic studies examining the response of model and crop species to seasonal cold offers new insight into the evolutionary lability of these traits. This insight has major implications for our understanding of complex trait evolution, and the potential role of local adaptation in response to past and future climate change. In this review, we discuss the biochemical, morphological, and developmental basis of adaptations to seasonal cold, and synthesize recent literature on the genetic basis of these traits in a phylogenomic context. We find evidence for multiple genetic links between distinct physiological responses to cold, possibly reinforcing the coordinated expression of these traits. Furthermore, repeated recruitment of the same or similar ancestral pathways suggests that land plants might be somewhat pre-adapted to dealing with temperature stress, perhaps making inducible cold traits relatively easy to evolve.

  6. In-line and real-time process monitoring of a freeze drying process using Raman and NIR spectroscopy as complementary process analytical technology (PAT) tools.

    Science.gov (United States)

    De Beer, T R M; Vercruysse, P; Burggraeve, A; Quinten, T; Ouyang, J; Zhang, X; Vervaet, C; Remon, J P; Baeyens, W R G

    2009-09-01

    The aim of the present study was to examine the complementary properties of Raman and near infrared (NIR) spectroscopy as PAT tools for the fast, noninvasive, nondestructive and in-line process monitoring of a freeze drying process. Therefore, Raman and NIR probes were built in the freeze dryer chamber, allowing simultaneous process monitoring. A 5% (w/v) mannitol solution was used as model for freeze drying. Raman and NIR spectra were continuously collected during freeze drying (one Raman and NIR spectrum/min) and the spectra were analyzed using principal component analysis (PCA) and multivariate curve resolution (MCR). Raman spectroscopy was able to supply information about (i) the mannitol solid state throughout the entire process, (ii) the endpoint of freezing (endpoint of mannitol crystallization), and (iii) several physical and chemical phenomena occurring during the process (onset of ice nucleation, onset of mannitol crystallization). NIR spectroscopy proved to be a more sensitive tool to monitor the critical aspects during drying: (i) endpoint of ice sublimation and (ii) monitoring the release of hydrate water during storage. Furthermore, via NIR spectroscopy some Raman observations were confirmed: start of ice nucleation, end of mannitol crystallization and solid state characteristics of the end product. When Raman and NIR monitoring were performed on the same vial, the Raman signal was saturated during the freezing step caused by reflected NIR light reaching the Raman detector. Therefore, NIR and Raman measurements were done on a different vial. Also the importance of the position of the probes (Raman probe above the vial and NIR probe at the bottom of the sidewall of the vial) in order to obtain all required critical information is outlined. Combining Raman and NIR spectroscopy for the simultaneous monitoring of freeze drying allows monitoring almost all critical freeze drying process aspects. Both techniques do not only complement each other, they also

  7. Influence of Stress Treatments on the Resistance of Lactococcus lactis to Freezing and Freeze-Drying

    OpenAIRE

    Lin, Chan

    1998-01-01

    This study investigated the effect of cold, heat, or osmotic shock treatment on the resistance of L. lactis subsp. cremoris MM160 and MM310 and Lactococcus lactis subsp. lactis MM210 and FG2 cheese starter bacteria to freezing and freeze-drying. The ability to withstand freezing at -60°C for 24 h was variable among lactococci, but resistance to this treatment was significantly improved (P < 0.05) in most strains by a 2-h cold shock at l0°C or a 25-min heat shock at 39°C (L. lactis subsp. crem...

  8. ARCTIC FOUNDATIONS, INC. FREEZE BARRIER TECHNOLOGY; INNOVATIVE TECHNOLOGY EVALUATION REPORT

    Science.gov (United States)

    Arctic Foundations, Inc. (AFI), of Anchorage, Alaska has developed a freeze barrier technology designed to prevent the migration of contaminants in groundwater by completely isolating contaminant source areas until appropriate remediation techniques can be applied. With this tech...

  9. ARCTIC FOUNDATIONS, INC. FREEZE BARRIER SYSTEM - SITE TECHNOLOGY CAPSULE

    Science.gov (United States)

    Arctic Foundations, Inc. (AFI), of Anchorage, Alaska has developed a freeze barrier technology designed to prevent the migration of contaminants in groundwater by completely isolating contaminant source areas until appropriate remediation techniques can be applied. With this tec...

  10. Microwave Enhanced Freeze Drying of Solid Waste Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The development of advanced methods for Microwave Enhanced Freeze Drying of Solid Waste (MEFDSW) is proposed. Methods for the recovery of relatively pure water as a...

  11. Universality of Tip Singularity Formation in Freezing Water Drops

    CERN Document Server

    Marin, Alvaro G; Brunet, Philipe; Colinet, Pierre; Snoeijer, Jacco H

    2014-01-01

    A drop of water deposited on a cold plate freezes into an ice drop with a pointy tip. While this phenomenon clearly finds its origin in the expansion of water upon freezing, a quantitative description of the tip singularity has remained elusive. Here we demonstrate how the geometry of the freezing front, determined by heat transfer considerations, is crucial for the tip formation. We perform systematic measurements of the angles of the conical tip, and reveal the dynamics of the solidification front in a Hele-Shaw geometry. It is found that the cone angle is independent of substrate temperature and wetting angle, suggesting a universal, self-similar mechanism that does not depend on the rate of solidification. We propose a model for the freezing front and derive resulting tip angles analytically, in good agreement with observations.

  12. Multiphoton imaging of biological samples during freezing and heating

    Science.gov (United States)

    Breunig, H. G.; Uchugonova, A.; König, K.

    2014-02-01

    We applied multiphoton microscopic imaging to observe freezing and heating effects in plant- and animal cell samples. The experimental setups consisted of a multiphoton imaging system and a heating and cooling stage which allows for precise temperature control from liquid nitrogen temperature (-196°C 77 K) up to +600°C (873 K) with heating/freezing rates between 0.01 K/min and 150 K/min. Two multiphoton imaging systems were used: a system based on a modified optical microscope and a flexible mobile system. To illustrate the imaging capabilities, plant leafs as well as animal cells were microscopically imaged in vivo during freezing based on autofluorescence lifetime and intensity of intrinsic molecules. The measurements illustrate the usefulness of multiphoton imaging to investigate freezing effects on animal and plant cells.

  13. REDOX ASPECTS REGARDING PRESERVATION OF VEGETAL FOOD PRODUCTS BY FREEZING

    Directory of Open Access Journals (Sweden)

    Cristinel Zanoaga

    2007-08-01

    Full Text Available Freezing, at least of the vegetable products, no matter of the anatomic part involved – root, stalk, leaf, flower, fruit or seed – induces a biochemical changes manifested, implicitly, by modification of the tissular rH. More precisely, the more distant the native rH of the product under consideration is from a certain value – apparently the optimum/compatible to the animal, consuming organism – (rH ~ 26, the deeper are the transformations it suffers as a result of freezing, namely: if the native rH takes values below 26, the product gets oxidized by freezing while, in the opposite case, it is reduced, as if the whole group of vegetal products would tend to attain – by means of freezing – a (redox homeostasis

  14. CURRENT TECHNOLOGY AND INNOVATIONS IN FREEZE SHAFT SINKING IN CHINA

    Institute of Scientific and Technical Information of China (English)

    张铭; 翁家杰; 夏正明

    1991-01-01

    This paper gives a brief review of the development of shaft sinking by artificial ground freezing since 1949 when new China was founded. Several shaft freezing schemes which have been successfully applied from the economic and safe viewpoints are presented. Current technology and some innovative techniques,especially the shah lining which have experienced major improvements over the last four decades,are briefly reviewed. The technique of the in-situ pour concrete incorporating ailica fume with higher early strength under low temperature curing conditions is described. The temperature field in shah freezing and its finite difference solution are given in this paper. A recently developed method combining freeze wall model test with back analysis technique based on numerical simulation is also described.

  15. Freezing Resistance of HPC with Nano-SiO2

    Institute of Scientific and Technical Information of China (English)

    WANG Baomin; WANG Lijiu; F C Lai

    2008-01-01

    The test of fast-freezing method is employed to research the freezing resistance of C60and C80 high-performance concrete with nanometer-SiO2,and XRD and SEM are employed to analyze the mechanism of its influence.The experimental results show that the freezing resistance of high-performance concrete has been effectively improved.The compressive strength of C60,C70 and C80 high-performance concrete added with nano-SiO2 can be improved by 8%,6% and 5% respectively,the weight loss can be reduced by 1%,0.6% and 0.3% respectively and the relative dynamic elastic modulus can be improved by 7%,4% and 6%respectively after the 300 times freeze-thaw cycle.

  16. Microwave Enhanced Freeze Drying of Solid Waste Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Development of technology for Microwave Enhanced Freeze Drying of Solid Waste (MEFDSW) is proposed. The present state of the art for solid waste stabilization using...

  17. Freeze concentration of dairy products Phase 2. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Best, D.E.; Vasavada, K.C.

    1993-09-01

    An efficient, electrically driven freeze concentration system offers potential for substantially increasing electricity demand while providing the mature dairy industry with new products for domestic and export markets together with enhanced production efficiencies. Consumer tests indicate that dairy products manufactured from freeze-concentrated ingredients are either preferred or considered equivalent in quality to fresh milk-based products. Economic analyses indicate that this technology should be competitive with thermal evaporation processes on a commercial basis.

  18. Freezing drillings at the shaft deepening at Lyukobanya in 1986

    Energy Technology Data Exchange (ETDEWEB)

    Csiszar, L.

    1988-01-01

    The preliminaries of freezing drilling in Hungary are summarized and the deepening of the Lyukobanya shaft by means of this method is discussed. The drilling equipment and the drilling parameters are listed and the incorporation of freezing tubes is dealt with in detail. The problems and measurement of vertical drilling with this technology are presented on the basis of experiments carried out on the Lyukobanya shaft.

  19. Study on the Efficiency of the Vegetables Freezing Process

    Directory of Open Access Journals (Sweden)

    Simona Paulikienė

    2014-10-01

    Full Text Available Changes taking place during the storage of the products of vegetable origin are inevitable. Products can deteriorate and change their shelf appearance, nutritional value, texture, taste and aroma. Freezing is one of the most appropriate technological operations for the product storage. By freezing products of vegetable origin, cleaner production technology can be used to consume less energy and to preserve quality of the product as well as valuable nutritional/ biologically active substances.The study of vegetable freezing process was carried out by freezing red beets. Beetroot was frozen in a chamber with controlled climatic environment - the Feutron.A portion of moisture content always evaporates from products of vegetable origin at freezing. Air flow velocity has a great influence on freezing rate of vegetables. Intensity of moisture evaporation also increases up to the moment of freezing-up of the surface layers.Intensity of retardation of the evaporation process depends on a peel and on stomata on it. Moisture evaporation’s retardation rate of the red beet peel εevp.ap = 0,50 ± 0,02. When air velocity was 0,15 m/s - εevp varied from 0,47 to 0,53, whilst at the air flow velocity 0,65 m/s - εevp = 0,37 – 0,45.Purpose of the study - to analyse the freezing process of vegetables (by the red beetroot example under the influence of different environment factors.DOI: http://dx.doi.org/10.5755/j01.erem.69.3.6064

  20. In cryptozoospermia or severe oligozoospermia is sperm freezing useful?

    OpenAIRE

    Bessonnat, Julien; Brouillet, Sophie; Sintzel, Sarah; Gillois, Pierre; Bergues, Ulrike; Boutte-Busquet, Caroline; Thomas-Cadi, Claire; Hennebicq, Sylviane

    2014-01-01

    Background Intracytoplasmic Sperm Injection (ICSI) is an Assisted Reproduction Technique (ART) which offers the chance to conceive to patients presenting very low sperm counts (cryptozoospermia/severe oligozoospermia). Sperm freezing before the oocyte pick-up, can prevent from a lack of spermatozoa on the day of the ICSI. It can avoid the cancellation of the ICSI or the use of TESE (Testicular sperm extraction). The objective of this study was to analyse the practice of sperm freezing for the...

  1. Freezing and Thawing Durability of Very High Strength Concrete

    Directory of Open Access Journals (Sweden)

    Sameer Hamoush

    2011-01-01

    Full Text Available Problem statement: The newly developed Very High Strength Concrete (VHSC, having compressive strengths of 29 ksi and flexural strengths of 6 ksi, represents a breakthrough in concrete technology. Study to further enhance the properties of this new concrete is continuing. Approach: The objective of this study is to investigate the effect of exposing Very High Strength Concrete (VHSC specimens to rapid freeze/thaw cycles. Twenty one specimens were tested according to the Standards of the American Society for Testing and Materials ASTM C215, ASTM C666 and ASTM C78. Results: One hundred freeze/thaw cycles were performed on the VHSC specimens. Change in specimen’s dimensions and material’s properties were recorded at zero, forty, seventy and one hundred cycles. Dimensions and properties considered were: dimension of cross section, length, weight, Dynamic Moduli, Poisson’s Ratio, durability factor and Modulus of Rupture. Conclusion/Recommendations: The test results indicated that VHSC is good freeze-thaw resistance (durability factor > 85% and can avoid freeze/thaw damage. Freeze- thaw cycling did not significantly affect VHSC specimens’ cross sectional dimensions, length, or Poisson’s Ratio. However, there was a decrease in the specimens’ weight with the increase in number of freeze/thaw cycles, but the decrease was very slim indicating little or no deterioration has occur. Moreover, the fine voids exist in VHSC greatly lower the freezing point of any trapped water, making the material less susceptible to Freeze- Thaw damage.

  2. 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 ...

  3. Evaluation and Comparison of Freeze-Thaw Tests and Air Void Analysis of Pervious Concrete

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Kevern, John T.;

    2016-01-01

    to eval-uate the freeze-thaw resistance of fresh or hardened pervious concrete and correspondingly what constitutes acceptable freeze-thaw durability. A greater understanding of the correlation between the freeze-thaw performance and the air void structure of pervious concrete is needed. In the present...... effectively relieve the pressure when water freezes....

  4. Freeze tolerance differs between two ecotypes of Paspalum vaginatum (Poaceae

    Directory of Open Access Journals (Sweden)

    Liliana Teresa Fabbri

    2016-03-01

    Full Text Available Morphological and physiological responses to freezing were evaluated in two ecotypes of the perennial turfgrass Paspalum vaginatum. Leaf extension rate, number of active meristems, leaf water potential and net photosynthesis were measured on plants of both a commercial cultivar, 'Sea Isle 2000', and a wild ecotype from the Flooding Pampa grasslands of Argentina. Plants were propagated by cloning, cultivated in pots, and examined during 18 consecutive days under two treatments: a non-frozen control treatment (15.5±7 ºC and a frozen treatment with two stages: Stage 1 with four hours of freezing stress for 10 nights (-5ºC, and Stage 2 with 12 hours of freezing stress for eight nights (five nights at -5ºC and three nights at -8ºC. After these treatments, plants were returned to the outside environment to evaluate shoot injury and post-freezing recovery. Leaf water potential, net photosynthesis and leaf extension rate were significantly higher in the wild ecotype than in the commercial cultivar. Meristem density was reduced after freezing in both ecotypes, but was more pronounced in the commercial cultivar (98.5% than in the wild ecotype (80%. Thus, the two ecotypes coming from different environments, exhibited different morphological and physiological responses to exposure to freezing temperatures.

  5. 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 synchronization during breeding season resulted in higher heat response and lambing rate than two injections given 10 days apart.

  6. Chapter 4 Electron transfer in respiratory complexes resolved by an ultra-fast freeze-quench approach.

    Science.gov (United States)

    Belevich, Nikolai P; Verkhovskaya, Marina L; Verkhovsky, Michael I

    2009-01-01

    The investigation of the molecular mechanism of the respiratory chain complexes requires determination of the time-dependent evolution of the catalytic cycle intermediates. The ultra-fast freeze-quench approach makes possible trapping such intermediates with consequent analysis of their chemical structure by means of different physical spectroscopic methods (e.g., EPR, optic, and Mössbauer spectroscopies). This chapter presents the description of a setup that allows stopping the enzymatic reaction in the time range from 100 microsec to tens of msec. The construction and production technology of the mixer head, ultra-fast freezing device, and accessories required for collecting a sample are described. Ways of solving a number of problems emerging on freezing of the reaction mixture and preparing the samples for EPR spectroscopy are proposed. The kinetics of electron transfer reaction in the first enzyme of the respiratory chain, Complex I (NADH: ubiquinone oxidoreductase), is presented as an illustration of the freeze-quench approach. Time-resolved EPR spectra indicating the redox state of FeS clusters of the wild-type and mutant (R274A in subunit NuoCD) Complex I from Escherichia coli are shown.

  7. 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.

  8. Defining asthma in genetic studies

    NARCIS (Netherlands)

    Koppelman, GH; Postma, DS; Meijer, G.

    1999-01-01

    Genetic studies have been hampered by the lack of a gold standard to diagnose asthma. The complex nature of asthma makes it more difficult to identify asthma genes. Therefore, approaches to define phenotypes, which have been successful in other genetically complex diseases, may be applied to define

  9. Antioxidant, antiproliferative and antimicrobial activity of freeze-dried raspberry

    Directory of Open Access Journals (Sweden)

    Vulić Jelena J.

    2014-01-01

    Full Text Available The main chemical composition, i.e. the total content of bioactive compounds (phenolics 2209.86 ± 70.32 mg GAE/100g FDR, flavonoids 831.87 ± 12.61 mg R/100g FDR and anthocyanins 144.55 ± 0.39 mg CGE/100g FDR, in freeze-dried raspberry (FDR was evaluated spectrophotometrically. Vitamin C content was determined by HPLC analysis (88.81 ± 4.38 mg vit C/100g FDR. Antioxidant activities of FDR extract were evaluated spectrophotometrically on stable 2,2-diphenyl-1-picrylhydrazyl (DPPH free radicals and by electron spin resonance spectroscopy (ESR method on hydroxyl radicals (•OH. EC50 values were evaluated. EC50 DPPH• was 0.127 ± 0.013 mg/ml, while EC50 •OH was 1.366 ± 0.026 mg/ml. Antiproliferative activity of the FDR extract was evaluated in vitro in three human cell lines by colorimetric sulphorhodamine B (SRB assay. The most pronounced effects were obtained in the breast adenocarcinoma cell line (MCF7. EC50 value was 395.07 ± 96.38 μg/ml. Antimicrobial activity was determined by disk diffusion method. The FDR extract produced a clear inhibition zone (without visible colonies only toward Staphylococcus aureus. The minimal inhibitory (MIC and minimal bactericidal (MBC concentrations of FDR extract were evaluated. The values MIC were in the range of 4.7 - 100 mg/ml, and of MBC in the range of 6.3 - > 100 mg/ml.[ Projekat Ministarstva nauke Republike Srbije, br. TR 31044

  10. Preparation and Characterization ofβ-TCP/CS Scaffolds by Freeze-extraction and Freeze-gelation

    Institute of Scientific and Technical Information of China (English)

    HAO Ruiran; WANG Deping; YAO Aihua; HUANG Wenhai

    2011-01-01

    The freeze-extraction and freeze-gelation methods were used to prepare highly porous β-TCP/CS scaffolds with different β-TCP/CS ratio. In these methods, the suspending mixture of β-TCP and chitosan was frozen, the frozen mixture was immersed in a non-solvent(0.05 mol/L NaOH/ehanol aqueous) bath to allow the exchange between solvent(acetic-acid aqueous) and non-solvent at a temperature lower than the freezing point of the acetic-acid. Then, the β-TCP/CS scaffolds were formed and dried at room temperature. Scanning electron microscopy (SEM), X-ray diffraction (XRD), gas chromatography (GC) and omnipotence material testing machine were employed to characterize theβ-TCP/CS scaffolds. The results of GC show that the freeze extraction of the β-TCP/chitosan scaffolds was completed when the extraction time is above 24 h. The SEM results show that the β-TCP/CS scaffolds are composed of interconnected pore network. The porosity of the β-TCP/CS scaffolds decrease with the increase of the content of the β-TCP. The β-TCP/CS scaffolds have a highest compressive strength when the chitosan/β-TCP ratio is 30:70. The present work displays that the β-TCP/CS composite scaffolds with appropriate mechanical properties and high porosity can be successfully prepared by the freeze-extraction and freeze-gelation methods.

  11. Repeated vitrification/warming of human sperm gives better results than repeated slow programmable freezing

    Institute of Scientific and Technical Information of China (English)

    Teraporn Vutyavanich; Worashorn Lattiwongsakorn; Waraporn Piromlertamorn; Sudarat Samchimchom

    2012-01-01

    In this study,we compared the effects of repeated freezing/thawing of human sperm by our in-house method of rapid freezing with slow programmable freezing.Sperm samples from 11 normozoospermic subjects were processed through density gradients and divided into three aliquots:non-frozen,rapid freezing and slow programmable freezing.Sperm in the rapid freezing group had better motility and viability than those in the slow freezing group (P<O.01) after the first,second and third cycles of freezing/thawing,but there was no difference in morphology.In the second experiment,rapid freezing was repeated three times in 20 subjects.The samples from each thawing cycle were evaluated for DNA fragmentation using the alkaline comet assay.DNA fragmentation began to increase considerably after the second cycle of freezing/thawing,but to a level that was not clinically important.In the third experiment,rapid freezing was done repeatedly in 10 subjects,until no motile sperm were observed after thawing.The median number of repeated freezing/thawing that yielded no motile sperm was seven (range:5-8,mean:6.8).In conclusion,we demonstrated that repeated freezing/thawing of processed semen using our rapid freezing method gave better results than standard slow programmable freezing.This method can help maximize the usage of precious cryopreserved sperm samples in assisted reproduction technology.

  12. Defining and Classifying Interest Groups

    DEFF Research Database (Denmark)

    Baroni, Laura; Carroll, Brendan; Chalmers, Adam;

    2014-01-01

    The interest group concept is defined in many different ways in the existing literature and a range of different classification schemes are employed. This complicates comparisons between different studies and their findings. One of the important tasks faced by interest group scholars engaged...... in large-N studies is therefore to define the concept of an interest group and to determine which classification scheme to use for different group types. After reviewing the existing literature, this article sets out to compare different approaches to defining and classifying interest groups with a sample...

  13. Does anxiety cause freezing of gait in Parkinson's disease?

    Directory of Open Access Journals (Sweden)

    Kaylena A Ehgoetz Martens

    Full Text Available Individuals with Parkinson's disease (PD commonly experience freezing of gait under time constraints, in narrow spaces, and in the dark. One commonality between these different situations is that they may all provoke anxiety, yet anxiety has never been directly examined as a cause of FOG. In this study, virtual reality was used to induce anxiety and evaluate whether it directly causes FOG. Fourteen patients with PD and freezing of gait (Freezers and 17 PD without freezing of gait (Non-Freezers were instructed to walk in two virtual environments: (i across a plank that was located on the ground (LOW, (ii across a plank above a deep pit (HIGH. Multiple synchronized motion capture cameras updated participants' movement through the virtual environment in real-time, while their gait was recorded. Anxiety levels were evaluated after each trial using self-assessment manikins. Freezers performed the experiment on two separate occasions (in their ON and OFF state. Freezers reported higher levels of anxiety compared to Non-Freezers (p < 0.001 and all patients reported greater levels of anxiety when walking across the HIGH plank compared to the LOW (p < 0.001. Freezers experienced significantly more freezing of gait episodes (p = 0.013 and spent a significantly greater percentage of each trial frozen (p = 0.005 when crossing the HIGH plank. This finding was even more pronounced when comparing Freezers in their OFF state. Freezers also had greater step length variability in the HIGH compared to the LOW condition, while the step length variability in Non-Freezers did not change. In conclusion, this was the first study to directly compare freezing of gait in anxious and non-anxious situations. These results present strong evidence that anxiety is an important mechanism underlying freezing of gait and supports the notion that the limbic system may have a profound contribution to freezing in PD.

  14. Rational design of an influenza subunit vaccine powder with sugar glass technology : preventing conformational changes of haemagglutinin during freezing and freeze-drying

    NARCIS (Netherlands)

    Amorij, J-P; Meulenaar, J; Hinrichs, W L J; Stegmann, T; Huckriede, A; Coenen, F; Frijlink, H W

    2007-01-01

    The development of a stable influenza subunit vaccine in the dry state was investigated. The influence of various carbohydrates, buffer types and freezing rates on the integrity of haemagglutinin after freeze-thawing or freeze-drying was investigated with a range of analytical and immunological meth

  15. Theoretical approaches to elections defining

    Directory of Open Access Journals (Sweden)

    Natalya V. Lebedeva

    2011-01-01

    Full Text Available Theoretical approaches to elections defining develop the nature, essence and content of elections, help to determine their place and a role as one of the major national law institutions in democratic system.

  16. Defining Modules, Modularity and Modularization

    DEFF Research Database (Denmark)

    Miller, Thomas Dedenroth; Pedersen, Per Erik Elgård

    The paper describes the evolution of the concept of modularity in a historical perspective. The main reasons for modularity are: create variety, utilize similarities, and reduce complexity. The paper defines the terms: Module, modularity, and modularization.......The paper describes the evolution of the concept of modularity in a historical perspective. The main reasons for modularity are: create variety, utilize similarities, and reduce complexity. The paper defines the terms: Module, modularity, and modularization....

  17. Development of Freeze-Dried Bacteriocin-Containing Preparations from Lactic Acid Bacteria to Inhibit Listeria monocytogenes and Staphylococcus aureus.

    Science.gov (United States)

    Dimitrieva-Moats, Galina Yu; Ünlü, Gülhan

    2012-03-01

    There has been a recent movement to produce and consume "minimally processed" and more "natural" foods through the use of fewer chemical preservatives. The shift to more "natural" foods has resulted in a great interest in the use of bacteriocins from lactic acid bacteria as natural biopreservatives. The objective of this comparative study was to identify bacteriocins that can be produced in low-cost or no-cost dairy-based media (DBM), concentrated using freeze-drying, and applied to Cheddar cheese samples to concurrently inhibit Listeria monocytogenes and Staphylococcus aureus. Select bacteriocin producers were grown in DBM, their cell-free supernatants (CFS) were frozen, and the frozen CFS samples were freeze-dried to produce bacteriocin-containing powders. Cheddar cheese samples were challenged with L. monocytogenes or Staph. aureus cells. The challenged samples were exposed to buffered solutions of freeze-dried powders containing bacteriocins, incubated at 4 °C for 24-72 h, and plated onto appropriate selective media. All freeze-dried bacteriocin-containing powders tested were active against L. monocytogenes and Staph. aureus. Our research findings indicated that low-cost or no-cost DBM could successfully be used for production of bacteriocin-containing preparations. In addition, freeze-drying was determined to be a feasible approach to prepare concentrated and stable bacteriocin-containing powders for prospective food applications. The prevention of even a very small percentage of foodborne illnesses via the use of bacteriocins as natural biopreservatives would help reduce the number of foodborne illness-related hospitalizations, deaths, and financial loss due to medical expenses, lost income/productivity, cost of litigation/penalties, and loss of trade.

  18. Preparation of Chitosan Nanocompositeswith a Macroporous Structure by Unidirectional Freezing and Subsequent Freeze-Drying

    Directory of Open Access Journals (Sweden)

    Inmaculada Aranaz

    2014-11-01

    Full Text Available Chitosan is the N-deacetylated derivative of chitin, a naturally abundant mucopolysaccharide that consists of 2-acetamido-2-deoxy-β-d-glucose through a β (1→4 linkage and is found in nature as the supporting material of crustaceans, insects, etc. Chitosan has been strongly recommended as a suitable functional material because of its excellent biocompatibility, biodegradability, non-toxicity, and adsorption properties. Boosting all these excellent properties to obtain unprecedented performances requires the core competences of materials chemists to design and develop novel processing strategies that ultimately allow tailoring the structure and/or the composition of the resulting chitosan-based materials. For instance, the preparation of macroporous materials is challenging in catalysis, biocatalysis and biomedicine, because the resulting materials will offer a desirable combination of high internal reactive surface area and straightforward molecular transport through broad “highways” leading to such a surface. Moreover, chitosan-based composites made of two or more distinct components will produce structural or functional properties not present in materials composed of one single component. Our group has been working lately on cryogenic processes based on the unidirectional freezing of water slurries and/or hydrogels, the subsequent freeze-drying of which produce macroporous materials with a well-patterned structure. We have applied this process to different gels and colloidal suspensions of inorganic, organic, and hybrid materials. In this review, we will describe the application of the process to chitosan solutions and gels typically containing a second component (e.g., metal and ceramic nanoparticles, or carbon nanotubes for the formation of chitosan nanocomposites with a macroporous structure. We will also discuss the role played by this tailored composition and structure in the ultimate performance of these materials.

  19. 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.

  20. 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.

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

    Science.gov (United States)

    Boonsupthip, W; Heldman, D R

    2007-06-01

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

  2. Enhanced enzymatic conversion with freeze pretreatment of rice straw

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Ken-Lin; Thitikorn-amorn, Jitladda; Ou, Bay-Ming; Chen, Shan-He; Huang, Po-Jung [Institute of Biological Chemistry and Genomics Research Center Academia Sinica, Nankang, Taipei 115 (China); Hsieh, Jung-Feng [Department of Food Science, Fu Jen Catholic University, Xin Zhuang, Taipei 242 (China); Ratanakhanokchai, Khanok [School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, Bangkok 10150 (Thailand); Chen, Shui-Tein [Institute of Biological Chemistry and Genomics Research Center Academia Sinica, Nankang, Taipei 115 (China); Institute of Biochemical Sciences, College of Life Science, National Taiwan University, Taipei 106 (China)

    2011-01-15

    Production of bioethanol by the conversion of lignocellulosic waste has attracted much interest in recent years, because of its low cost and great potential availability. The pretreatment process is important for increasing the enzymatic digestibility of lignocellulosic materials. Enzymatic conversion with freeze pretreatment of rice straw was evaluated in this study. The freeze pretreatment was found to significantly increase the enzyme digestibility of rice straw from 48% to 84%. According to the results, enzymatic hydrolysis of unpretreated rice straw with 150 U cellulase and 100 U xylanase for 48 h yielded 226.77 g kg{sup -1} and 93.84 g kg{sup -1} substrate-reducing sugars respectively. However, the reducing sugar yields from freeze pretreatment under the same conditions were 417.27 g kg{sup -1} and 138.77 g kg{sup -1} substrate, respectively. In addition, hydrolyzates analysis showed that the highest glucose yield obtained during the enzymatic hydrolysis step in the present study was 371.91 g kg{sup -1} of dry rice straw, following pretreatment. Therefore, the enhanced enzymatic conversion with freeze pretreatment of rice straw was observed in this study. This indicated that freeze pretreatment was highly effective for enzymatic hydrolysis and low environmental impact. (author)

  3. Freeze-In Dark Matter with Displaced Signatures at Colliders

    CERN Document Server

    Co, Raymond T; Hall, Lawrence J; Pappadopulo, Duccio

    2015-01-01

    Dark matter, $X$, may be generated by new physics at the TeV scale during an early matter-dominated (MD) era that ends at temperature $T_R \\ll {\\rm TeV}$. Compared to the conventional radiation-dominated (RD) results, yields from both Freeze-Out and Freeze-In processes are greatly suppressed by dilution from entropy production, making Freeze-Out less plausible while allowing successful Freeze-In with a much larger coupling strength. Freeze-In is typically dominated by the decay of a particle $B$ of the thermal bath, $B \\rightarrow X$. For a large fraction of the relevant cosmological parameter space, the decay rate required to produce the observed dark matter abundance leads to displaced signals at LHC and future colliders, for any $m_X$ in the range ${\\rm keV} < m_X < m_B$ and for values of $m_B$ accessible to these colliders. This result applies whether the early MD era arises after conventional inflation, when $T_R$ is the usual reheat temperature, or is a generic MD era with an alternative origin. I...

  4. Characterization of freeze-fractured epithelial plasma membranes on nanometer scale with ToF-SIMS.

    Science.gov (United States)

    Draude, Felix; Körsgen, Martin; Pelster, Andreas; Schwerdtle, Tanja; Müthing, Johannes; Arlinghaus, Heinrich F

    2015-03-01

    Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to characterize the freeze-fracturing process of human epithelial PANC-1 and UROtsa cells. For this purpose, phosphatidylcholine, sphingomyelin, phosphatidylethanolamine, and phosphatidylserine standard samples were investigated to find specific signals with both high specificity and signal intensity. The results were used to investigate single cells of subconfluent cell layers prepared with a special silicon wafer sandwich preparation technique. This freeze-fracturing technique strips cell membranes off the cells, isolating them on opposing silicon wafer substrates. Criteria were found for defining regions with stripped off cell membranes and, on the opposing wafer, complementary regions with the remaining cells. Measured ethanolamine/choline and serine/choline ratios in these regions clearly showed that in the freeze-fracturing process, the lipid bilayer of the plasma membrane is split along its central zone. Accordingly, only the outer lipid monolayer is stripped off the cell, while the inner lipid monolayer remains attached to the cell on the opposing wafer, thus allowing detailed analysis of a single lipid monolayer. Furthermore, it could be shown that using different washing procedures did not influence the transmembrane lipid distribution. Under optimized preparation conditions, it became feasible to detect lipids with a lateral resolution of approximately 100 nm. The data indicate that ToF-SIMS would be a very useful technique to study with very high lateral resolution changes in lipid composition caused, for example, by lipid storage diseases or pharmaceuticals that interfere with the lipid metabolism.

  5. Freeze-drying applied to radioactive source preparation.

    Science.gov (United States)

    de Sanoit, J; Leprince, B; Bobin, Ch; Bouchard, J

    2004-12-01

    In the framework of R&D studies for the improvement of radioactive source efficiencies prepared on thin films for 4pibeta-gamma coincidence counting, a comparative study on two drying methods has been undertaken in our laboratory (BNM-Laboratoire National Henri Becquerel, France). The standard method of evaporation at atmospheric pressure and a method based on freeze-drying using commercial equipment are compared. The preliminary results of this study obtained with 65Zn sources are presented and a significant improvement of the detection efficiencies to the electron emission for freeze-dried sources is shown. In the course of validation of this method, other radionuclides were studied and, up to now, the results confirm the better crystallization homogeneity achieved for freeze-dried sources.

  6. Surviving freezing in plant tissues by oomycetous snow molds.

    Science.gov (United States)

    Murakami, Ryo; Yajima, Yuka; Kida, Ken-ichi; Tokura, Katsuyuki; Tojo, Motoaki; Hoshino, Tamotsu

    2015-04-01

    Oomyceteous snow molds, Pythium species, were reported to be less tolerant to chilling and freezing temperatures than other snow mold taxa. However, Pythium species are often found to be pathogenic on mosses in Polar Regions. We investigated the frost resistance of Pythium species from Temperate (Hokkaido, Japan) and Subantarctic Regions. Free mycelia and hyphal swellings, structures for survival, of Pythium iwayamai and Pythium paddicum lost viability within freeze-thaw 3 cycles; however, mycelia in host plants survived the treatment. It was reported that fungi in permafrost are characterized both by the presence of natural cryoprotectants in these ecotopes and by the ability to utilize their inherent mechanisms of protection. It is conceivable that plant substrates or derivatives thereof are natural cryoprotectants, enabling them to provide advantageous conditions to microorganisms under freezing conditions. Our results are the first to experimentally support this hypothesis.

  7. 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.

  8. Freezing of gait: a practical approach to management.

    Science.gov (United States)

    Nonnekes, Jorik; Snijders, Anke H; Nutt, John G; Deuschl, Günter; Giladi, Nir; Bloem, Bastiaan R

    2015-07-01

    Freezing of gait is a common and disabling symptom in patients with parkinsonism, characterised by sudden and brief episodes of inability to produce effective forward stepping. These episodes typically occur during gait initiation or turning. Treatment is important because freezing of gait is a major risk factor for falls in parkinsonism, and a source of disability to patients. Various treatment approaches exist, including pharmacological and surgical options, as well as physiotherapy and occupational therapy, but evidence is inconclusive for many approaches, and clear treatment protocols are not available. To address this gap, we review medical and non-medical treatment strategies for freezing of gait and present a practical algorithm for the management of this disorder, based on a combination of evidence, when available, and clinical experience of the authors. Further research is needed to formally establish the merits of our proposed treatment protocol.

  9. Deconfinement of strangeness and freeze-out from charge fluctuations

    CERN Document Server

    Mukherjee, Swagato

    2013-01-01

    We use Lattice QCD calculations of fluctuations and correlations of various conserved charges to show that the deconfinement of strangeness takes place in the chiral crossover region of QCD; however, inside the quark-gluon plasma strange quarks remain strongly interacting at least up to temperatures twice the QCD crossover temperature. Further, we discuss how the freeze-out parameters of heavy-ion collisions can be determined in a model-independent way through direct comparisons between experimentally measured higher order cumulants of conserved charges and corresponding Lattice QCD calculations. Utilizing the preliminary data from the STAR and PHENIX experiments we illustrate this method. Although, the Lattice QCD based determinations of the freeze-out parameters utilizing data sets of different experiments and different observables are currently not consistent with each other, it is tantalizing to see that all the observed freeze-out parameters lie very close to the chiral/deconfinement crossover region of ...

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

    Science.gov (United States)

    Friedman, R.

    1979-01-01

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

  11. Modular Software-Defined Radio

    Directory of Open Access Journals (Sweden)

    Rhiemeier Arnd-Ragnar

    2005-01-01

    Full Text Available In view of the technical and commercial boundary conditions for software-defined radio (SDR, it is suggestive to reconsider the concept anew from an unconventional point of view. The organizational principles of signal processing (rather than the signal processing algorithms themselves are the main focus of this work on modular software-defined radio. Modularity and flexibility are just two key characteristics of the SDR environment which extend smoothly into the modeling of hardware and software. In particular, the proposed model of signal processing software includes irregular, connected, directed, acyclic graphs with random node weights and random edges. Several approaches for mapping such software to a given hardware are discussed. Taking into account previous findings as well as new results from system simulations presented here, the paper finally concludes with the utility of pipelining as a general design guideline for modular software-defined radio.

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

    Science.gov (United States)

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

    2012-01-01

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

  13. 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.

  14. Ultrasonic emissions from conifer xylem exposed to repeated freezing.

    Science.gov (United States)

    Mayr, Stefan; Zublasing, Verena

    2010-01-01

    Ultrasonic emission measurements enable the analysis of xylem cavitation induced by drought and freeze-thaw events. Several studies have indicated that ultrasonic acoustic emissions (UAE) in conifers occur upon freezing and not upon thawing, although classical theory has postulated gas bubble formation during freezing and cavitation during thawing. We analyzed the pattern and quality of freeze-thaw-induced UAE in seven conifers (Abies alba, Larix decidua, Juniperus communis, Picea abies, Pinus cembra, Pinus mugo, Pinus sylvestris). Axes samples dehydrated to different water potentials were exposed to repeated frost cycles. The number, amplitude and energy of UAE signals were registered and related to water potential, temperature course and wood characteristics (wood density, tracheid diameter). For P. abies, ultrasonic emission analysis was also performed on bark samples, xylem samples without bark, as well as on stems of young potted trees. In all conifers, UAE were registered in water-stressed samples but not in saturated or dehydrated samples. No signals were emitted by the bark of P. abies. Ultrasonic activity occurred only upon freezing, and identical patterns were observed in axes samples and stems of potted P. abies trees. A weak positive relationship between tracheid diameter and UAE energy was observed, indicating wide tracheids to emit signals with higher energy. The classical bubble formation hypothesis cannot sufficiently explain the occurrence of UAE during freezing and upon repeated temperature cycles, as demonstrated in this study. We suggest that the low water potential of ice induces air-seeding near the ice-water interface, and consequently, causes UAE.

  15. Defining the Internet of Things

    OpenAIRE

    Benghozi, Pierre-Jean; Bureau, Sylvain; Massit-Folléa, Françoise

    2012-01-01

    How can a definition be given to what does not yet exist ? The Internet of Things, as it is conceptualized by researchers or imagined by science-fiction writers such as Bruce Sterling, is not yet reality and if we try to define it accurately we risk rash predictions. In order to better comprehend this notion, let us first define the main principles of the IoT as given in research papers and reports on the subject. Definitions gradually established Almost all agree that the Internet of Things...

  16. Experimental Investigation of Thermal Conductivity of Meat During Freezing

    Science.gov (United States)

    Shinbayeva, A.; Arkharov, I.; Aldiyarov, A.; Drobyshev, A.; Zhubaniyazova, M.; Kurnosov, V.

    2017-04-01

    The cryogenic technologies of processing and storage of agricultural products are becoming increasingly indispensable in the food industry as an important factor of ensuring food safety. One of such technologies is the shock freezing of meat, which provides a higher degree of preservation of the quality of frozen products in comparison with traditional technologies. The thermal conductivity of meat is an important parameter influencing the energy consumption in the freezing process. This paper presents the results of an experimental investigation of the temperature dependence of the thermal conductivity of beef. The measurements were taken by using a specially designed measurement cell, which allows covering the temperature range from 80 to 300 K.

  17. On freeze-out problem in relativistic hydrodynamics

    CERN Document Server

    Ivanov, Yu B

    2008-01-01

    A finite unbound system which is equilibrium in one reference frame is in general nonequilibrium in another frame. This is a consequence of the relative character of the time synchronization in the relativistic physics. This puzzle was a prime motivation of the Cooper--Frye approach to the freeze-out in relativistic hydrodynamics. Solution of the puzzle reveals that the Cooper--Frye recipe is far not a unique phenomenological method that meets requirements of energy-momentum conservation. Alternative freeze-out recipes are considered and discussed.

  18. Field application of freezing technology for social infrastructures

    Institute of Scientific and Technical Information of China (English)

    EunChul Shin; YuRa Gong; CheolGyu Jeong

    2015-01-01

    There are numerous methods to prevent seepage flow and ground improvement methodologies such as cement grouting, sheet piling, and the membrane method. In this paper, we present case histories of freezing technology applications in the construction of a deep tunnel sewerage system, undersea highway tunnel, and liquefied natural gas tank. Heaving pressure measurements for various soil types around a liquefied natural tank are compared with existing data. In this paper, we present temperature variations at the bottom and side of a liquefied natural gas tank. Our findings show that ground-freezing technology is very effective in controlling ground water infiltration into underground structures as well providing soil reinforcement in the soft ground.

  19. High freezing point fuels used for aviation turbine engines

    Science.gov (United States)

    Friedman, R.

    1979-01-01

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

  20. Random spin freezing in uranium intermetallic compound UCuSi

    Energy Technology Data Exchange (ETDEWEB)

    Li Dexin [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nimori, Shigeki [Tsukuba Magnet Laboratory, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0003 (Japan); Shiokawa, Yoshinobu [Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan)

    2006-03-29

    The results of low-temperature ac susceptibility, dc magnetization, magnetic relaxation, specific heat, and electrical resistivity measurements on the uranium intermetallic compound UCuSi, a hexagonal CeCd{sub 2}-type non-magnetic atom disorder system, are reported. The results establish that a spin-glass state is formed in this compound at low temperature. Some dynamical parameters characterizing the spin freezing state of this system, such as static spin freezing temperature T{sub s}, critical exponent z{nu}, and activation energy E{sub a}, are determined from dynamical analysis of the ac susceptibility data. The observed properties are discussed based on a magnetic cluster model.

  1. Empirical formula for the refractive index of freezing brine

    DEFF Research Database (Denmark)

    Frisvad, Jeppe Revall

    2009-01-01

    The refractive index of freezing brine is important for example in order to estimate oceanic scattering as sea ice develops. Previously, no simple continuous expression was available for estimating the refractive index of brine at subzero temperatures. I show that extrapolation of the empirical...... formula for the refractive index of seawater by Quan and Fry [Appl. Opt. 34(18), 3477-3480 (1995)] provides a good fit to the refractive index of freezing brine for temperatures above -24 degrees celsius and salinities below 180 parts per thousand....

  2. Ambient in-situ immersion freezing measurements - findings from the ZAMBIS 2014 field campaign for three ice nucleation techniques

    Science.gov (United States)

    Kohn, Monika; Atkinson, James D.; Lohmann, Ulrike; Kanji, Zamin A.

    2015-04-01

    well as a droplet freezing method on aerosol particles either collected in a suspension or on PM10-filters to obtain atmospheric IN concentrations based on the measured ambient aerosol. Investigation of physical properties (number and size distribution) and chemical composition as well as the meteorological conditions provide supplementary information that help to understand the nature of particles and air masses that contribute to immersion freezing. Acknowledgements We thank Hannes Wydler and Hansjörg Frei from ETH Zurich for their technical support. Furthermore, the authors want thank Franz Conen from the University of Basel for sharing equipment and training in the drop freezing experiment. References [1] Chou et al. (2011), Atmos. Chem. Phys., 11, 4725-4738. [2] Nicolet et al. (2010), Atmos. Chem. Phys., 10, 313-325. [3] Conen et al. (2012), Atmos. Meas. Tech., 5, 321-327. [4] Stopelli et al. (2014), Atmos. Meas. Tech., 7, 129-134.

  3. Defining and Measuring User Experience

    DEFF Research Database (Denmark)

    Stage, Jan

    2006-01-01

    on the intrinsic relation between definition and measurement. In the area of usability, this relation has been developed over several years. It is described how usability is defined and measured in contemporary approaches. Based on that, it is discussed to what extent we can employ experience from the conceptual...

  4. Defining sphincter of oddi dysfunction

    DEFF Research Database (Denmark)

    Funch-Jensen, P

    1996-01-01

    Sphincter of Oddi (SO) dysmotility may give rise to pain. The golden standard for the demonstration of SO dysfunction is endoscopic manometry. A number of abnormalities are observed in patients with postcholecystectomy pain and in patients with idiopathic recurrent pancreatitis. Criteria for defi...... for defining SO dysfunction and the possible mechanisms for the precipitation of pain are discussed....

  5. Defined medium for Moraxella bovis.

    Science.gov (United States)

    Juni, E; Heym, G A

    1986-10-01

    A defined medium (medium MB) for Moraxella bovis was formulated. Nineteen strains grew well on medium MB. One strain was auxotrophic for asparagine, and another was auxotrophic for methionine. Strains of M. equi and M. lacunata also grew on medium MB. All strains had an absolute requirement for thiamine and were stimulated by or actually required the other growth factors in the medium.

  6. Defined medium for Moraxella bovis.

    OpenAIRE

    1986-01-01

    A defined medium (medium MB) for Moraxella bovis was formulated. Nineteen strains grew well on medium MB. One strain was auxotrophic for asparagine, and another was auxotrophic for methionine. Strains of M. equi and M. lacunata also grew on medium MB. All strains had an absolute requirement for thiamine and were stimulated by or actually required the other growth factors in the medium.

  7. Structure-Property-Processing Correlations in Freeze-Cast Hybrid Scaffolds

    Science.gov (United States)

    Hunger, Philipp Malte

    Porous materials are highly sought after for applications ranging from catalyst carriers to tissue scaffolds. Most applications require clearly defined structural features and a specific mechanical performance. Therefore, it is essential to establish systematic structure-property-processing correlations to be able to tailor both structure and mechanical properties for a particular application. Because the introduction of porosity is detrimental to the mechanical performance of highly porous structures, it is necessary to generate a structure that allows for the mechanical properties to be maximized. One example for such a structure are honeycombs. In addition to the porosity and pore morphology, the scaffold's performance depends on the properties inherent to the material from which it is made. Polymeric foams possess high toughness but low stiffness, whereas ceramic foams possess high stiffness but low toughness. Natural composites like bone, antler and nacre have both high stiffness and high toughness. This unusual set of mechanical properties is thought to be intricately linked to the multi-level hierarchical composite structure present in these materials. Great potential for the fabrication of stiff, strong and tough porous scaffolds is thus seen in nacre-like composite materials with a hierarchical, honeycomb-like structure. Freeze casting is a method with which such hybrid materials can be made, adding the third dimension to nacre by forming a highly porous, hierarchical bulk material, with dense, nacre-like cell walls. The nacre-like cell walls self-assemble during the directional freezing of a water-based ceramic-polymer slurry. Reported here are structure-property-processing correlations observed in these materials. They are unusual, because they are, like nacre, solely glued by a polymeric phase and not processed further by sintering. The results illustrate several pathways to control both structure and mechanical properties in freeze-cast composites and

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-01-15

    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.

  9. Production of grape juice powder obtained by freeze-drying after concentration by reverse osmosis

    Directory of Open Access Journals (Sweden)

    Poliana Deyse Gurak

    2013-12-01

    Full Text Available This study aimed to evaluate the freeze-drying process for obtaining grape juice powder by reverse osmosis using 50% grape juice pre-concentrated (28.5 °Brix and 50% hydrocolloids (37.5% maltodextrin and 12.5% arabic gum. The morphology of the glassy food showed the absence of crystalline structure, which was the amorphous wall that protected the contents of the powder. The samples were stored in clear and dark containers at room temperature, evaluated for their physical (X-ray diffraction for 65 days and chemical (polyphenol content stability for 120 days. During the storage time in plastic vessels, samples remained physically stable (amorphous and the phenolic concentration was constant, indicating the potentiality of this technique to obtain a stable product with a high concentration of phenolic compounds. Therefore, the freeze-drying process promoted the encapsulation of concentrated grape juice increasing its stability and shelf life, as well as proving to be an applicable process to food industry

  10. Reconstructing the Freeze-out State in Pb + Pb Collisions at 158 AGeV/c

    CERN Document Server

    Tomasik, Boris; Heinz, Ulrich W; Tomasik, Boris; Wiedemann, Urs Achim; Heinz, Ulrich

    2003-01-01

    For a class of analytical parametrizations of the freeze-out state of relativistic heavy ion collisions, we perform a simultaneous analysis of the single-particle m_t-spectra and two-particle Bose-Einstein correlations measured in central Pb+Pb collisions at the CERN SPS. The analysis includes a full model parameter scan with chi^2 confidence levels. A comparison of different transverse density profiles for the particle emission region allows for a quantitative discussion of possible model dependencies of the results. Our fit results suggest a low thermal freeze-out temperature T approximately 95 +- 15 MeV and a large average transverse flow velocity of about 0.55c +- 0.07c. Moreover, the fit favours a box-shaped transverse density profile over a Gaussian one. We discuss the origins and the consequences of these results in detail. In order to reproduce the measured pion multiplicity our model requires a positive pion chemical potential. A study of the pion phase-space density indicates \\mu_\\pi approximately 6...

  11. Cash Freeze for E-Rate Hits Schools

    Science.gov (United States)

    Borja, Rhea R.

    2004-01-01

    A freeze on $3.28 billion in requests for aid under the federal E-rate program has left hundreds of school districts scrambling to pay for their technology needs--and, in some cases, crippled classroom instruction. The E-rate program, which has disbursed more than $8 billion since its inception in 1997, helps link public and private schools as…

  12. 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

  13. Improving the Quality of Freeze Dried Rice: Initial Evaluations

    Science.gov (United States)

    2015-05-01

    UNCLASSIFIED UNCLASSIFIED Improving the Quality of Freeze Dried Rice: Initial Evaluations Lan Bui and Ross Coad Land ...RELEASE LIMITATION Approved for public release ` UNCLASSIFIED UNCLASSIFIED Published by Land Division DSTO...techniques and final characteristics. The people of India, Bangladesh, Nepal, Sri Lanka, Pakistan, Burma and Thailand generally prefer a cooked rice

  14. Freeze-dried bone in pulpotomy procedures in monkey.

    Science.gov (United States)

    Fadavi, S; Anderson, A W; Punwani, I C

    1989-01-01

    The purpose of this study was to evaluate the effect of freeze-dried bone on amputated pulps. Fifteen primary and one permanent monkey teeth were treated with freeze-dried bone. As the control group, another fifteen primary teeth were treated with calcium hydroxide and fifteen primary and one permanent teeth with formocresol. Four other primary teeth pulps were amputated and sealed with tin foil and IRM as controls. Twelve mandibular incisors were left intact. Histologically all but three teeth treated with human freeze-dried bone after three months showed a complete or partial calcific barrier directly below the amputation site. Normal appearing odontoblastic cells were noted below the calcific barrier. The apical third was vital with an occasional chronic inflammatory cell visible. The histological findings of teeth treated with calcium-hydroxide were very similar to freeze-dried bone. All but four teeth showed a complete calcific barrier at the amputation site. The odontoblastic cells were normal in appearance and the inflammatory cell reactions decreased from the middle portion toward the apical region. The histological evaluation of the formocresol-treated teeth was comparable with previously published studies.

  15. 40 CFR 52.1135 - Regulation for parking freeze.

    Science.gov (United States)

    2010-07-01

    ... from acts of God, strikes, litigation, or other matters beyond the control of the owner shall be... of any such existing facility in the freeze area unless and until he has obtained from the Governor... conform to the requirements of 40 CFR 51.4(b); and the agency rules or procedures may provide that if...

  16. IMPACT OF FREEZING OF FCAS: THE CASE OF PAKISTAN

    Directory of Open Access Journals (Sweden)

    Hafiz Abdur Rashi

    2011-09-01

    Full Text Available Foreign investment and foreign exchange reserves have ample importance for developing countries. So, there is a needed to encourage the foreign and domestic investors whose confidence was suffer by the unexpected decision of freezing of FCAs. The purpose of this study was to identify the areas that were affected after the decision of freezing of FCAs. Moreover, the impact of freezing decision on economy of Pakistan also indicated. More sophisticated impact on banking sector, balance of payment, foreign exchange reserves, foreign debt, and foreign investment. Study found the negative impact of freezing decision of FCAs on foreign banking and positive impact on domestic banking but Pakistan banking sector was disconnected from the international banking; insatiability in balance of payment was increased; the foreign investment and exports was reduced.Resultantly, foreign exchange reserves were reduced and foreign exchange rates was increased. Therefore, it is suggested to increase the confidence of foreign investors in order to increase the foreign investment and foreign exchange reserves. Discussion of conclusions and recommendations were also provided.

  17. Freeze desalination of seawater using LNG cold energy

    KAUST Repository

    Chang, Jian

    2016-06-23

    With the aid of cold energy from regasification of liquefied natural gas (LNG), freeze desalination (FD) is an emerging technology for seawater desalination because of its low energy characteristics and insensitivities to fouling problems. This work aims to investigate the major operating parameters of FD such as coolant temperature, freezing duration, supercooling, seeding, agitation, crystallizer material and subsequent washing procedure on ice production and water quality. It was found that the optimal freezing duration per batch was 1 h for an iron crystallizer and 1.5 h for a glass crystallizer. The optimal coolant temperature should be around −8 °C. The optimal amount of washing water to clean the raw ice was about 50 wt% of the raw ice. Over 50 wt% of the feed could be recovered as raw ice within 1 h, which means an overall ice recovery rate of higher than 25% (of the original seawater), considering the consumption of washing water. Both artificial and real seawater were tested under the optimized conditions. The total dissolved solid in the product ice was around 300 ppm, which met the World Health Organization (WHO) potable water salinity standard of 500 ppm. Therefore, the process parameters optimized in this study can be directly used for the freeze desalination of seawater.

  18. A novel approach to sterile pharmaceutical freeze-drying.

    Science.gov (United States)

    Cherry, Christopher Lee Albert; Millward, Huw; Cooper, Rose; Landon, John

    2014-02-01

    A novel approach has been developed that enables sterile pharmaceutical products to be freeze-dried in the open laboratory without specialist facilities. The product is filled into vials, semi-stoppered and sealed inside one, followed by a second, sterilization pouch under class 100 conditions. The product is then freeze-dried in the laboratory where the vials are shelf-stoppered before being returned to class 100, unwrapped and crimped. The sterilization pouches increased the resistance to water vapor movement during sublimation, thereby increasing the sublimation time and product temperature. Ovine immunoglobulins were double wrapped and lyophilized (as above) adjusting the primary drying time and shelf temperature for increased product temperature and, therefore, prevention of collapse. Ovine immunoglobulin G formulations freeze-dried to ≤ 1.1% residual moisture with no effect on protein aggregation or biological activity. The process was simulated with tryptone soya broth and no growth of contaminating microbial cells was observed after incubation at 35 °C for 2 weeks. Although increasing lyophilization time, this approach offers significant plant and validation cost savings when sterile freeze-drying small numbers of vials thereby making the manufacture of treatments for neglected and orphan diseases more viable economically.

  19. Freezing Point Depressions of Phase Change CO2 Solvents

    DEFF Research Database (Denmark)

    Arshad, Muhammad Waseem; Fosbøl, Philip Loldrup; von Solms, Nicolas;

    2013-01-01

    Freezing point depressions (FPD) in phase change solvents containing 2-(diethylamino)ethanol (DEEA) and 3-(methylamino)propylamine (MAPA) were measured using a modified Beckmann apparatus. The measurements were performed for the binary aqueous DEEA and MAPA solutions, respectively, in the concent...

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

    NARCIS (Netherlands)

    Borgomaneri, Sara; Vitale, Francesca; Gazzola, V.; Avenanti, Alessio

    2015-01-01

    Fearful body language is a salient signal alerting the observer to the presence of a potential threat in the surrounding environment. Although detecting potential threats may trigger an immediate reduction of motor output in animals (i.e., freezing behavior), it is unclear at what point in time simi

  1. 7 CFR 58.638 - Freezing the mix.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Freezing the mix. 58.638 Section 58.638 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE (CONTINUED) REGULATIONS AND STANDARDS UNDER...

  2. Freeze desalination of seawater using LNG cold energy.

    Science.gov (United States)

    Chang, Jian; Zuo, Jian; Lu, Kang-Jia; Chung, Tai-Shung

    2016-10-01

    With the aid of cold energy from regasification of liquefied natural gas (LNG), freeze desalination (FD) is an emerging technology for seawater desalination because of its low energy characteristics and insensitivities to fouling problems. This work aims to investigate the major operating parameters of FD such as coolant temperature, freezing duration, supercooling, seeding, agitation, crystallizer material and subsequent washing procedure on ice production and water quality. It was found that the optimal freezing duration per batch was 1 h for an iron crystallizer and 1.5 h for a glass crystallizer. The optimal coolant temperature should be around -8 °C. The optimal amount of washing water to clean the raw ice was about 50 wt% of the raw ice. Over 50 wt% of the feed could be recovered as raw ice within 1 h, which means an overall ice recovery rate of higher than 25% (of the original seawater), considering the consumption of washing water. Both artificial and real seawater were tested under the optimized conditions. The total dissolved solid in the product ice was around 300 ppm, which met the World Health Organization (WHO) potable water salinity standard of 500 ppm. Therefore, the process parameters optimized in this study can be directly used for the freeze desalination of seawater.

  3. Growing bubbles and freezing drops: depletion effects and tip singularities

    NARCIS (Netherlands)

    Enríquez Paz y Puente, Oscar Raúl

    2015-01-01

    In this thesis, the author investigates the growth of gas bubbles in a supersaturated solution and the freezing of water drops when placed on a cold plate. Supersaturated solutions are common in nature and industry; perhaps the best know examples are carbonated drinks, such as beer or soda. These ar

  4. Brain imaging in patients with freezing of gait

    NARCIS (Netherlands)

    Bartels, Anna L.; Leenders, Klaus L.

    2008-01-01

    Freezing of gait (FOG) is a disabling gait disturbance with unknown cerebral pathophysiology. In this review, we discuss the functional brain imaging Studies that address gait physiology and pathophysiology of FOG. Radiotracer metabolic studies show basal ganglia-cortical circuitry involvement in di

  5. Freeze granulation for the processing of silicon nitride ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Lyckfeldt, O. [Swedish Ceramic Inst., Goeteborg (Sweden); Rundgren, K. [Permascand AB, Ljungaverk (Sweden); Sjoestedt, M. [PowderPro HB, Hisings Backa (Sweden)

    2004-07-01

    Freeze granulation (LS-2, PowderPro HB, Sweden) has been demonstrated as a favourable alternative to conventional granulation methods (spray drying, sieve granulation etc) in the production of granules for the pressing of high-performance ceramic powders. Freeze granulation/freeze drying prevents the migration of pressing aids or particle fines to the granule surface, as is the case in spray drying. This ensures granule homogeneity and an easy breakdown of granules during pressing. This, in turn, results in defect minimisation and optimal conditions for the sintering and the development of the desired material properties. In this study silicon nitride materials have been produced using freeze granulation, pressing and sintering to validate the performance. Materials with competitive properties were manufactured based on medium-cost, direct-nitrided powders (SicoNide P95, Permascand AB, Sweden), various pressing and sintering aid compositions as well as various pressing and sintering schedules. MgO vs Fe{sub 2}O{sub 3} as sintering aid, PEG vs PVA as binder and higher pressure at the initial uniaxial pressing were found to promote the sintering performance. (orig.)

  6. 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.

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

    Science.gov (United States)

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

    2011-12-01

    Results of experimental researches of "optical microcable in a microduct" system stability to effect of freezing water are presented. It is shown this system is steadier to water freezing in comparison to lighten optical cable in protective polymer tube.

  8. Software defined radio architectures evaluation

    OpenAIRE

    Palomo, Alvaro; Villing, Rudi; Farrell, Ronan

    2008-01-01

    This paper presents an performance evaluation of GNU Radio and OSSIE, two open source Software Defined Radio (SDR) architectures. The two architectures were compared by running implementations of a BPSK waveform utilising a software loopback channel on each. The upper bound full duplex throughput was found to be around 700kbps in both cases, though OSSIE was slightly faster than GNU Radio. CPU and memory loads did not differ significantly.

  9. AIDS defining disease: Disseminated cryptococcosis

    Directory of Open Access Journals (Sweden)

    Roshan Anupama

    2006-01-01

    Full Text Available Disseminated cryptococcosis is one of the acquired immune deficiency syndrome defining criteria and the most common cause of life threatening meningitis. Disseminated lesions in the skin manifest as papules or nodules that mimic molluscum contagiosum (MC. We report here a human immunodeficiency virus positive patient who presented with MC like lesions. Disseminated cryptococcosis was confirmed by India ink preparation and histopathology. The condition of the patient improved with amphotercin B.

  10. Does Magnetic Levitation or Suspension Define the Masses of Forming Stars?

    CERN Document Server

    Shu, F H; Allen, A; Shu, Frank H.; Li, Zhi-Yun; Allen, Anthony

    2004-01-01

    We investigate whether magnetic tension can define the masses of forming stars by holding up the subcritical envelope of a molecular cloud that suffers gravitational collapse of its supercritical core. We perform an equilibrium analysis of the initial and final states assuming perfect field freezing, no rotation, isothermality, and a completely flattened configuration. The sheet geometry allows us to separate the magnetic tension into a levitation associated with the split monopole formed by the trapped flux of the central star and a suspension associated with curved field lines that thread the static pseudodisk and envelope of material external to the star. We find solutions where the eigenvalue for the stellar mass is a fixed multiple of the initial core mass of the cloud. We verify the analytically derived result by an explicit numerical simulation of a closely related 3-D axisymmetric system. However, with field freezing, the implied surface magnetic fields much exceed measured values for young stars. If ...

  11. How to define green adjuvants.

    Science.gov (United States)

    Beck, Bert; Steurbaut, Walter; Spanoghe, Pieter

    2012-08-01

    The concept 'green adjuvants' is difficult to define. This paper formulates an answer based on two approaches. Starting from the Organisation for Economic Cooperation and Development (OECD) definition for green chemistry, production-based and environmental-impact-based definitions for green adjuvants are proposed. According to the production-based approach, adjuvants are defined as green if they are manufactured using renewable raw materials as much as possible while making efficient use of energy, preferably renewable energy. According to the environmental impact approach, adjuvants are defined as green (1) if they have a low human and environmental impact, (2) if they do not increase active ingredient environmental mobility and/or toxicity to humans and non-target organisms, (3) if they do not increase the exposure to these active substances and (4) if they lower the impact of formulated pesticides by enhancing the performance of active ingredients, thus potentially lowering the required dosage of active ingredients. Based on both approaches, a tentative definition for 'green adjuvants' is given, and future research and legislation directions are set out.

  12. Redox-freezing and nucleation of diamond via magnetite formation in the Earth's mantle

    Science.gov (United States)

    Jacob, Dorrit E.; Piazolo, Sandra; Schreiber, Anja; Trimby, Patrick

    2016-06-01

    Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800 km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies an arrested redox reaction from pyrrhotite to magnetite included in diamond. The magnetite corona shows coherent epitaxy with relict pyrrhotite and diamond, indicating that diamond nucleated on magnetite. Furthermore, structures inherited from h-Fe3O4 define a phase transformation at depths of 320-330 km, the base of the Kaapvaal lithosphere. The oxidation of pyrrhotite to magnetite is an important trigger of diamond precipitation in the upper mantle, explaining the presence of these phases in diamonds.

  13. Redox-freezing and nucleation of diamond via magnetite formation in the Earth's mantle.

    Science.gov (United States)

    Jacob, Dorrit E; Piazolo, Sandra; Schreiber, Anja; Trimby, Patrick

    2016-06-21

    Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800 km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies an arrested redox reaction from pyrrhotite to magnetite included in diamond. The magnetite corona shows coherent epitaxy with relict pyrrhotite and diamond, indicating that diamond nucleated on magnetite. Furthermore, structures inherited from h-Fe3O4 define a phase transformation at depths of 320-330 km, the base of the Kaapvaal lithosphere. The oxidation of pyrrhotite to magnetite is an important trigger of diamond precipitation in the upper mantle, explaining the presence of these phases in diamonds.

  14. Freezing-Thawing Characteristics of Botanical Tissues and Influence of Water Morphology

    Institute of Scientific and Technical Information of China (English)

    WU Hai-Ling; MA Yuan; PENG Xiao-Feng

    2004-01-01

    @@ A series of visualization experiments were conducted to investigate the transport phenomena and interface behaviour during the freezing-thawing process of typical botanical tissues. Attention was paid to the growth of ice crystals and the advance of the phase-change interface. A comparison was made to identify the freezing/thawing behaviour for different tissues under various freezing conditions. Based on the experimental observation, analyses were conducted to explore the influence of water morphology on the freezing/thawing characteristics.

  15. 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.

  16. Combined multi-nozzle deposition and freeze casting process to superimpose two porous networks for hierarchical three-dimensional microenvironment.

    Science.gov (United States)

    Snyder, Jessica E; Hunger, Philipp M; Wang, Chengyang; Hamid, Qudus; Wegst, Ulrike G K; Sun, Wei

    2014-03-01

    An engineered three-dimensional scaffold with hierarchical porosity and multiple niche microenvironments is produced using a combined multi-nozzle deposition-freeze casting technique. In this paper we present a process to fabricate a scaffold with improved interconnectivity and hierarchical porosity. The scaffold is produced using a two-stage manufacturing process which superimposes a printed porous alginate (Alg) network and a directionally frozen ceramic-polymer matrix. The combination of two processes, multi-nozzle deposition and freeze casting, provides engineering control of the microenvironment of the scaffolds over several length scales; including the addition of lateral porosity and the ratio of polymer to ceramic microstructures. The printed polymer scaffold is submerged in a ceramic-polymer slurry and subsequently, both structures are directionally frozen (freeze cast), superimposing and patterning both microenvironments into a single hierarchical architecture. An optional additional sintering step removes the organic material and densifies the ceramic phase to produce a well-defined network of open pores and a homogenous cell wall material composition. The techniques presented in this contribution address processing challenges, such as structure definition, reproducibility and fine adjustments of unique length scales, which one typically encounters when fabricating topological channels between longitudinal and transverse porous networks.

  17. Sensory properties determined by starch type in white sauces: effects of freeze/thaw and hydrocolloid addition.

    Science.gov (United States)

    Arocas, A; Sanz, T; Salvador, A; Varela, P; Fiszman, S M

    2010-03-01

    The effect of 5 types of starch (rice, potato, waxy corn, corn, and modified waxy corn) on the sensory properties of white sauces was studied. A comparative study was also made of variations resulting from freezing/thawing and effect of replacing 0.15% starch with 2 nonstarchy hydrocolloids, xanthan gum (XG), or locust bean gum (LBG) in samples to be frozen. The sensory properties were studied through descriptive analysis by a panel of 10 trained judges. Principal components analysis and cluster analysis were used to group each of the samples according to the scores for consistency, resilience, graininess, thickness, heterogeneity, creaminess, and mouth coating, the sensory attributes which were chosen to define the sauces under study. Significant differences were found between the different starches employed: the rice and modified starches presented similar behavior to each other, as did the potato starch and corn starch, while the waxy starch sauce stood apart from the rest because of its resilience. The freeze/thaw cycle had the greatest effect on the corn-starch sauce, increasing its graininess and heterogeneity values owing to retrogradation. Adding XG or LBG to the sauces subjected to a period of freezing/thawing did not have a significant effect on the sensory attributes of the reheated sauces made with rice, potato, or waxy or modified starch, but lower graininess and heterogeneity values were observed in the sauce made with corn starch.

  18. Chemical warfare in freshwater

    NARCIS (Netherlands)

    Mulderij, Gabi

    2006-01-01

    Aquatic macrophytes can excrete chemical substances into their enviroment and these compounds may inhibit the growth of phytoplankton. This process is defined as allelopathy: one organism has effects on another via the excretion of a (mixture of) chemical substance(s). With laboratory and field expe

  19. Impact of the industrial freezing process on selected vegetables -Part II. Colour and bioactive compounds

    NARCIS (Netherlands)

    Mazzeo, Teresa; Paciulli, Maria; Chiavaro, Emma; Visconti, Attilio; Fogliano, Vincenzo; Ganino, Tommaso; Pellegrini, Nicoletta

    2015-01-01

    In the present study, the impact of the different steps (i.e. blanching, freezing, storage following the industrial freezing process and the final cooking prior to consumption) of the industrial freezing process was evaluated on colour, chlorophylls, lutein, polyphenols and ascorbic acid content

  20. The impact of freeze-drying on microstructure and rehydration properties of carrot

    NARCIS (Netherlands)

    Voda, A.; Homan, N.; Witek, M.; Duijster, A.; Dalen, van G.; Sman, van der R.G.M.; Nijsse, J.; Vliet, van L.J.; As, van H.; Duynhoven, van J.P.M.

    2012-01-01

    The impact of freeze-drying, blanching and freezing rate pre-treatments on the microstructure and on the rehydration properties of winter carrots were studied by µCT, SEM, MRI and NMR techniques. The freezing rate determines the size of ice crystals being formed that leave pores upon drying. Their a

  1. 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... vitro diagnostic use. (a) Identification. Cell-freezing apparatus and reagents for in vitro diagnostic use are devices used to freeze human red blood cells for in vitro diagnostic use. (b)...

  2. Gelatin-Filtered Consomme: A Practical Demonstration of the Freezing and Thawing Processes

    Science.gov (United States)

    Lahne, Jacob B.; Schmidt, Shelly J.

    2010-01-01

    Freezing is a key food processing and preservation technique widely used in the food industry. Application of best freezing and storage practices extends the shelf-life of foods for several months, while retaining much of the original quality of the fresh food. During freezing, as well as its counterpart process, thawing, a number of critical…

  3. Microstructure and Dynamic Failure Properties of Freeze-Cast Materials for Thermobaric Warhead Cases

    Science.gov (United States)

    2012-12-01

    LIST OF FIGURES Figure 1. Freeze cast process: slurry preparation, solidification, sublimation and sintering (From Ref 6...the process can be divided into four steps, illustrated in Figure 1. 6 Figure 1. Freeze cast process: slurry preparation, solidification...DYNAMIC FAILURE PROPERTIES OF FREEZE- CAST MATERIALS FOR THERMOBARIC WARHEAD CASES by Yi Ming Tan December 2012 Thesis Advisor: Joseph

  4. Freeze drying of red blood cells: the use of directional freezing and a new radio frequency lyophilization device.

    Science.gov (United States)

    Arav, Amir; Natan, Dity

    2012-08-01

    Red blood cell (RBC) units are administered routinely into patients expressing a wide range of acute and chronic conditions (e.g., anemia, traumatic bleeding, chronic diseases, and surgery). The modern blood banking system has been designed to answer this need and assure a continuous, high quality blood supply to patients. However, RBCs units can be stored under hypothermic conditions for only up to 42 days, which leads to periodic shortages. Cryopreservation can solve these shortages, but current freezing methods employ high glycerol concentrations, which need to be removed and the cells washed prior to transfusion, resulting in a long (more than 1 hour) and cumbersome washing step. Thus, frozen RBCs have limited use in acute and trauma situations. In addition, transportation of frozen samples is complicated and costly. Freeze drying (lyophilization) of RBCs has been suggested as a solution for these problems, since it will allow for a low weight sample to be stored at room temperature, but reaching this goal is not a simple task. We studied the effect of different solutions (IMT2 and IMT3) containing trehalose and antioxidants or trehalose and human serum albumin, respectively, on freezing/thawing and freeze drying of RBCs. In addition, we evaluated the effect of cells concentrations and cooling rates on the post thaw and post rehydration recoveries of the RBCs. Finally, we developed a new radio frequency (RF) lyophilization device for a more rapid and homogeneous sublimation process of the frozen RBCs samples. Recovery and free Hb were measured as well as oxygen association/dissociation and cell's deformability. We found that IMT3 (0.3 M trehalose and 10% HSA) solution that was directionally frozen at a rapid interface velocity of 1 mm/sec (resulting in a cooling rate of 150°C/min) yielded the best results (better than IMT2 solution and slow interface velocity). Freeze thawing gave 100% survival, while freeze drying followed by rehydration with 20% dextran-40k

  5. Chemical Biology is.....

    OpenAIRE

    2007-01-01

    Chemical Biology is a relatively new field, and as such is not yet simply or succinctly defined. It includes such a wide range of fundamental problems that this commentary could only include just a few snapshots of potential areas of interest. Overarching themes and selected recent successes and ideas in chemical biology are described to illustrate broadly the scope of the field, but should not be taken as exhaustive. The Chemical Biology Section of Chemistry Central Journal is pleased to rec...

  6. Survival of Campylobacter spp. in poultry meat preparations subjected to freezing, refrigeration, minor salt concentration, and heat treatment.

    Science.gov (United States)

    Sampers, Imca; Habib, Ihab; De Zutter, Lieven; Dumoulin, Ann; Uyttendaele, Mieke

    2010-02-28

    The survival of Campylobacter spp. under defined conditions of freezing (-22 degrees C) was studied in naturally contaminated chicken skin and minced chicken meat. A decline of approximately one log(10) cfu/g was observed after 1 day of freezing. No further significant reduction was achieved by prolonged storage in the freezer, although a tendency for further gradual reduction of the numbers of Campylobacter spp. present was noted. Campylobacter spp. could still be detected qualitatively (per 0.1g) after 84 days. In a second part of this study, the survival of Campylobacter spp. in a typical minced meat preparation (minced meat supplemented with 1.5% salt (NaCl)) stored at refrigeration (4 degrees C) or frozen (-22 degrees C) was studied. No significant reduction of the pathogen was observed if the minced chicken meat was kept at 4 degrees C for 14 days, opposite to approximately one log(10) cfu/g reduction after 1 day when the minced meat preparation was stored in the freezer (-22 degrees C) for 14 days. The latter reduction is imputed to the effect of freezing as mentioned above and not due to the supplementation of NaCl to minced meat or the combination of NaCl and freezing, because similar reductions of Campylobacter spp. were noticed when minced meat (without addition of NaCl) was frozen. Finally, in a third part of the study, the survival of Campylobacter spp. subjected to a heat treatment, conform to consumer-based pan-frying, in inoculated (4.5+/-0.2 cfu/g) as well as naturally contaminated chicken burgers (2.1+/-0.1 cfu/g) was studied. The Campylobacter spp. numbers declined after 2 min (internal temperature reached circa 38 degrees C), where after 4 min (internal temperature reached circa 57.5 degrees C) they dropped below detectable levels (<10 cfu/g).

  7. Italian WEEE management system and treatment of end-of-life cooling and freezing equipments for CFCs removal.

    Science.gov (United States)

    Sansotera, M; Navarrini, W; Talaeemashhadi, S; Venturini, F

    2013-06-01

    This study presents and analyzes the data of the Italian system for take-back and recovery of waste electrical and electronic equipments (WEEEs) in the start-up period 2008-2010. The analysis was focused particularly on the data about the treatment of end-of-life cooling and freezing equipments. In fact, the wastes of cooling and freezing equipments have a high environmental impact. Indeed, in their compressor oil and insulation polyurethane (PU) foams chlorofluorocarbon (CFC) ozone-depleting gases are still present. In the period 2001-2004 Northern Italy resulted the main source in Europe of CFCs. The European Directive on WEEE management was enacted in 2002, but in Italy it was implemented by the legislative Decree in 2005 and it became operational in 2008. Actually, in 2008 the national WEEE Coordination Centre was founded in order to organize the WEEE pick-up process and to control collection, recovery and recycling targets. As a result, in 2010 the average WEEE collection per capita exceeded the threshold of more than 4 kg per inhabitant, as well as cooling and freezing appliances represented more than one fourth of the Italian WEEE collection stream. During the treatment of end-of-life cooling and freezing equipments, CFCs were recovered and disposed principally by burner methods. The analyses of defined specimens collected in the treatment facilities were standardized to reliably determine the amount of recovered CFCs. Samples of alkaline solid salt, alkaline saline solution, polyurethane matrix and compressor oil collected during the audit assessment procedure were analyzed and the results were discussed. In particular, the analysis of PU samples after the shredding and the warm pressing procedures measured a residual CFCs content around 500-1300 mg/kg of CFCs within the foam matrix.

  8. Mini-ribozymes and freezing environment: a new scenario for the early RNA world

    Directory of Open Access Journals (Sweden)

    A. V. Vlassov

    2005-11-01

    Full Text Available The RNA World hypothesis states that the present-day life, which is based on DNA genomes and protein enzymes, was preceded by a simpler life form based primarily on RNA. During this era, the genetic information resided in the sequence of RNA molecules and the phenotype derived from the catalytic properties of RNA. Though it is a widely accepted scenario, a number of problems remain unsolved. One of the biggest questions is how complex RNAs could evolve, survive and replicate under typically assumed ''warm and wet'' conditions, taking into account that the RNA phosphodiester backbone is chemically unstable under these conditions. We suggest that prebiotic conditions associated with freezing could have been of key importance in the early RNA World, and discuss the role of primitive catalytic RNA in the evolution of RNA size and complexity.

  9. Probing freeze-out conditions in heavy ion collisions with moments of charge fluctuations

    CERN Document Server

    Karsch, Frithjof

    2011-01-01

    We calculate the first four moments of baryon number, electric charge and strangeness fluctuations within the hadron resonance gas model. Different moments and their ratios as well as skewness and kurtosis are evaluated on the phenomenologically determined freeze-out curve in the temperature, baryon chemical potential plane. The model results and its predictions as well as relations between different moments are compared with the first data on net proton fluctuations in Au-Au collisions obtained at RHIC by the STAR Collaboration. We find good agreement between the model calculations and experimental results. We also point out that higher order moments should be more sensitive to critical behavior and will also distinguish hadron resonance gas model calculations from results obtained from lattice QCD.

  10. Chemical potential dependence of particle ratios within a unified thermal approach

    Science.gov (United States)

    Bashir, I.; Nanda, H.; Uddin, S.

    2016-06-01

    A unified statistical thermal freeze-out model (USTFM) is used to study the chemical potential dependence of identified particle ratios at mid-rapidity in heavy-ion collisions. We successfully reproduce the experimental data ranging from SPS energies to LHC energies, suggesting the statistical nature of the particle production in these collisions and hence the validity of our approach. The behavior of the freeze-out temperature is studied with respect to chemical potential. The freeze-out temperature is found to be universal at the RHIC and LHC and is close to the QCD predicted phase transition temperature, suggesting that the chemical freeze-out occurs soon after the hadronization takes place.

  11. UNIQLO, Define Your Own Fashion

    Institute of Scientific and Technical Information of China (English)

    Wang Ting

    2009-01-01

    @@ Yes,women like and enjoy shopping.Always,they want to buy some well-designed clothes with the most 'in'factors; and what's of the great importance,they would like to hear the words:"wow! You fit the wear well!"However,the most satisfied right things could not be always waiting for you there or you would not help complaining the so-fast changing trends day by day.At that time,why not to seek some delights from the basic classic collections?UNIQLO maybe is a choice for you to define your own fashion.

  12. Ultrastructure of the endocytotic pathway in glutaraldehyde-fixed and high-pressure frozen/freeze-substituted protoplasts of white spruce (Picea glauca).

    Science.gov (United States)

    Galway, M E; Rennie, P J; Fowke, L C

    1993-11-01

    An ultrastructural study of endocytosis has been made for the first time in protoplasts of a gymnosperm, white spruce (Picea glauca), fixed by high-pressure freezing and freeze substitution. Protoplasts derived from the WS1 line of suspension-cultured embryogenic white spruce were labelled with cationized ferritin, a non-specific marker of the plasma membrane. The timing of cationized ferritin uptake and its subcellular distribution were determined by fixing protoplasts at various intervals after labelling. To address concerns about using chemical fixation to study the membrane-bound transport of cationized ferritin, protoplasts were fixed both by conventional glutaraldehyde fixation and by rapid freezing in a Balzers high-pressure freezing apparatus (followed by freeze substitution). Cationized ferritin appeared rapidly in coated pits and coated vesicles after labelling. Later it was present in uncoated vesicles, and in Golgi bodies, trans-Golgi membranes and partially coated reticula, then subsequently in multivesicular bodies, which may ultimately fuse with and deliver their contents to lytic vacuoles. The results show that the time course and pathway of cationized ferritin uptake in the gymnosperm white spruce is very similar to the time course and pathway elucidated for cationized ferritin uptake in the angiosperm soybean. High-pressure freezing yielded much better preservation of intracellular membranes and organelles, although plasma membranes appeared ruffled. Protoplasts fixed by both methods possessed numerous smooth vesicles in the cortex and smooth invaginations of the plasma membrane. These became labelled with cationized ferritin, but apparently did not contribute directly to the internalization of cationized ferritin, except via the formation of coated pits and vesicles from their surfaces.

  13. Summer freezing resistance: a critical filter for plant community assemblies in Mediterranean high mountains

    Directory of Open Access Journals (Sweden)

    David Sánchez Pescador

    2016-02-01

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

  14. Defining life: the virus viewpoint.

    Science.gov (United States)

    Forterre, Patrick

    2010-04-01

    Are viruses alive? Until very recently, answering this question was often negative and viruses were not considered in discussions on the origin and definition of life. This situation is rapidly changing, following several discoveries that have modified our vision of viruses. It has been recognized that viruses have played (and still play) a major innovative role in the evolution of cellular organisms. New definitions of viruses have been proposed and their position in the universal tree of life is actively discussed. Viruses are no more confused with their virions, but can be viewed as complex living entities that transform the infected cell into a novel organism-the virus-producing virions. I suggest here to define life (an historical process) as the mode of existence of ribosome encoding organisms (cells) and capsid encoding organisms (viruses) and their ancestors. I propose to define an organism as an ensemble of integrated organs (molecular or cellular) producing individuals evolving through natural selection. The origin of life on our planet would correspond to the establishment of the first organism corresponding to this definition.

  15. Defining Life: The Virus Viewpoint

    Science.gov (United States)

    Forterre, Patrick

    2010-04-01

    Are viruses alive? Until very recently, answering this question was often negative and viruses were not considered in discussions on the origin and definition of life. This situation is rapidly changing, following several discoveries that have modified our vision of viruses. It has been recognized that viruses have played (and still play) a major innovative role in the evolution of cellular organisms. New definitions of viruses have been proposed and their position in the universal tree of life is actively discussed. Viruses are no more confused with their virions, but can be viewed as complex living entities that transform the infected cell into a novel organism—the virus—producing virions. I suggest here to define life (an historical process) as the mode of existence of ribosome encoding organisms (cells) and capsid encoding organisms (viruses) and their ancestors. I propose to define an organism as an ensemble of integrated organs (molecular or cellular) producing individuals evolving through natural selection. The origin of life on our planet would correspond to the establishment of the first organism corresponding to this definition.

  16. Freezing resistance of first grade soybean oil%一级大豆油抗冻性研究

    Institute of Scientific and Technical Information of China (English)

    王化林; 马传国; 殷俊俊; 裴梦雪

    2014-01-01

    该文研究了市售4种一级大豆油的部分理化指标、脂肪酸组成、甘三酯组成、甘一酯、甘二酯以及甾醇含量对其低温下抗冻性的影响。通过自制实验装置对大豆油进行冷冻试验和对大豆油固体脂肪含量的测定结果表明,脂肪酸组成、甘三酯组成、酸值、碘值、过氧化值、甘一酯含量对4种一级大豆油的抗冻性没有直接影响,而甘二酯的含量对一级大豆油抗冻性有一定影响。%The influence of the composition of fatty acids and triglycerides,part of the chemical indictors and the content of monoglycerides,diglycerides and sterols of the first grade soybean oils to their freezing resistance were evaluated here. According to the freezing experiments carried by the self-made experimental facility and the determination of the solid fat content of soybean oils,the results indicated that,the composition of fatty acids and triglycerides,iodine value,acid value,peroxide value,and the content of monoglycerides,and sterols had no direct influence on the freezing resistance, whereas the content of diglycerides had a certain influence on the freezing resistance of the first grade soybean oil.

  17. Chemical nonequilibrium for interacting bosons: Applications to the pion gas

    Science.gov (United States)

    Fernández-Fraile, D.; Gómez Nicola, A.

    2009-09-01

    We consider an interacting pion gas in a stage of the system evolution where thermal but not chemical equilibrium has been reached, i.e., for temperatures between thermal and chemical freeze-out TtherLuscher and Gell-Mann-Oakes-Renner-type relations. We pay special attention to the comparison with the conventional kinetic theory approach in the dilute regime, which allows for a check of consistency of our approach. Several phenomenological applications are discussed, concerning chiral symmetry restoration, freeze-out conditions, and Bose-Einstein pion condensation.

  18. Conserved Charge Susceptibilities in a Chemically Frozen Hadronic Gas

    CERN Document Server

    Ang'ong'a, Jackson

    2015-01-01

    In a hadronic gas with three conserved charges (electric charge, baryon number, and strangeness) we employ the hadron resonance gas model to compute both diagonal and off-diagonal susceptibilities. We model the effect of chemical freeze-out in two ways: one in which all particle numbers are conserved below the chemical freeze-out temperature and one which takes into account resonance decays. We then briefly discuss possible implications these results may have on two active areas of research, hydrodynamic fluctuations and the search for the QCD critical point.

  19. Technology Advances and Mechanistic Modelling in Freeze-drying and Dehydration of Food

    Directory of Open Access Journals (Sweden)

    Wanren Chen

    2015-08-01

    Full Text Available Aim of study is to introduce some advanced freeze-drying technology and mechanistic modelling in freeze-drying and dehydration of food, freeze-drying is based on the dehydration by sublimation of a frozen product, due to very low temperature, all the deterioration activity and microbiological activity are stopped and provide better quality to the final product. Meanwhile the main problems of the freeze-dried food were proposed and its prospect and outlook was also analyzed, expecting to obtain technical and theoretical support for the production of freeze-drying food.

  20. Experimental investigations of freezing soils at ground conditions of Astana, Kazakhstan

    Institute of Scientific and Technical Information of China (English)

    Zhussupbekov Askar; Shakhmov Zhanbolat

    2015-01-01

    Kazakhstan regions is seasonal climatic with transient freezing of soil ground during the winter. Roadbed integrity is important to resist the sustained load transmitted by traffic on the road surface. Freezing of soil ground could significantly influence roadbed integrity in the seasonal freezing climate of Kazakhstan. The proper determination magnitude of frost heave and heaving pressure by the influence of freezing temperatures during the winter season are necessary for design and construction of highways. Thus, experimental tests were conducted on specimens obtained from Astana (Kazakhstan) to determine the freezing pressure and magnitude of frost heaving.

  1. Effects of Artificial Supercooling Followed by Slow Freezing on the Microstructure and Qualities of Pork Loin

    OpenAIRE

    Kim, Yiseul; Hong, Geun-Pyo

    2016-01-01

    This study investigated the effects of artificial supercooling followed by still air freezing (SSF) on the qualities of pork loin. The qualities of pork frozen by SSF were compared with the fresh control (CT, stored at 4℃ for 24 h), slow freezing (SAF, still air freezing) and rapid freezing (EIF, ethanol immersion freezing) treatments. Compared with no supercooling phenomena of SAF and EIF, the extent of supercooling obtained by SSF treatment was 1.4℃. Despite that SSF was conducted with the ...

  2. Defining life: synthesis and conclusions.

    Science.gov (United States)

    Gayon, Jean

    2010-04-01

    The first part of the paper offers philosophical landmarks on the general issue of defining life. Section 1 defends that the recognition of "life" has always been and remains primarily an intuitive process, for the scientist as for the layperson. However we should not expect, then, to be able to draw a definition from this original experience, because our cognitive apparatus has not been primarily designed for this. Section 2 is about definitions in general. Two kinds of definition should be carefully distinguished: lexical definitions (based upon current uses of a word), and stipulative or legislative definitions, which deliberately assign a meaning to a word, for the purpose of clarifying scientific or philosophical arguments. The present volume provides examples of these two kinds of definitions. Section 3 examines three traditional philosophical definitions of life, all of which have been elaborated prior to the emergence of biology as a specific scientific discipline: life as animation (Aristotle), life as mechanism, and life as organization (Kant). All three concepts constitute a common heritage that structures in depth a good deal of our cultural intuitions and vocabulary any time we try to think about "life". The present volume offers examples of these three concepts in contemporary scientific discourse. The second part of the paper proposes a synthesis of the major debates developed in this volume. Three major questions have been discussed. A first issue (Section 4) is whether we should define life or not, and why. Most authors are skeptical about the possibility of defining life in a strong way, although all admit that criteria are useful in contexts such as exobiology, artificial life and the origins of life. Section 5 examines the possible kinds of definitions of life presented in the volume. Those authors who have explicitly defended that a definition of life is needed, can be classified into two categories. The first category (or standard view) refers

  3. Defining Life: Synthesis and Conclusions

    Science.gov (United States)

    Gayon, Jean

    2010-04-01

    The first part of the paper offers philosophical landmarks on the general issue of defining life. §1 defends that the recognition of “life” has always been and remains primarily an intuitive process, for the scientist as for the layperson. However we should not expect, then, to be able to draw a definition from this original experience, because our cognitive apparatus has not been primarily designed for this. §2 is about definitions in general. Two kinds of definition should be carefully distinguished: lexical definitions (based upon current uses of a word), and stipulative or legislative definitions, which deliberately assign a meaning to a word, for the purpose of clarifying scientific or philosophical arguments. The present volume provides examples of these two kinds of definitions. §3 examines three traditional philosophical definitions of life, all of which have been elaborated prior to the emergence of biology as a specific scientific discipline: life as animation (Aristotle), life as mechanism, and life as organization (Kant). All three concepts constitute a common heritage that structures in depth a good deal of our cultural intuitions and vocabulary any time we try to think about “life”. The present volume offers examples of these three concepts in contemporary scientific discourse. The second part of the paper proposes a synthesis of the major debates developed in this volume. Three major questions have been discussed. A first issue (§4) is whether we should define life or not, and why. Most authors are skeptical about the possibility of defining life in a strong way, although all admit that criteria are useful in contexts such as exobiology, artificial life and the origins of life. §5 examines the possible kinds of definitions of life presented in the volume. Those authors who have explicitly defended that a definition of life is needed, can be classified into two categories. The first category (or standard view) refers to two conditions

  4. Defining biocultural approaches to conservation.

    Science.gov (United States)

    Gavin, Michael C; McCarter, Joe; Mead, Aroha; Berkes, Fikret; Stepp, John Richard; Peterson, Debora; Tang, Ruifei

    2015-03-01

    We contend that biocultural approaches to conservation can achieve effective and just conservation outcomes while addressing erosion of both cultural and biological diversity. Here, we propose a set of guidelines for the adoption of biocultural approaches to conservation. First, we draw lessons from work on biocultural diversity and heritage, social-ecological systems theory, integrated conservation and development, co-management, and community-based conservation to define biocultural approaches to conservation. Second, we describe eight principles that characterize such approaches. Third, we discuss reasons for adopting biocultural approaches and challenges. If used well, biocultural approaches to conservation can be a powerful tool for reducing the global loss of both biological and cultural diversity.

  5. Network Coded Software Defined Networking

    DEFF Research Database (Denmark)

    Krigslund, Jeppe; Hansen, Jonas; Roetter, Daniel Enrique Lucani;

    2015-01-01

    Software Defined Networking (SDN) and Network Coding (NC) are two key concepts in networking that have garnered a large attention in recent years. On the one hand, SDN's potential to virtualize services in the Internet allows a large flexibility not only for routing data, but also to manage...... buffering, scheduling, and processing over the network. On the other hand, NC has shown great potential for increasing robustness and performance when deployed on intermediate nodes in the network. This new paradigm changes the dynamics of network protocols, requiring new designs that exploit its potential....... This paper advocates for the use of SDN to bring about future Internet and 5G network services by incorporating network coding (NC) functionalities. The inherent flexibility of both SDN and NC provides a fertile ground to envision more efficient, robust, and secure networking designs, that may also...

  6. Network Coded Software Defined Networking

    DEFF Research Database (Denmark)

    Hansen, Jonas; Roetter, Daniel Enrique Lucani; Krigslund, Jeppe

    2015-01-01

    Software defined networking has garnered large attention due to its potential to virtualize services in the Internet, introducing flexibility in the buffering, scheduling, processing, and routing of data in network routers. SDN breaks the deadlock that has kept Internet network protocols stagnant...... for decades, while applications and physical links have evolved. This article advocates for the use of SDN to bring about 5G network services by incorporating network coding (NC) functionalities. The latter constitutes a major leap forward compared to the state-of-the- art store and forward Internet paradigm....... The inherent flexibility of both SDN and NC provides fertile ground to envision more efficient, robust, and secure networking designs, which may also incorporate content caching and storage, all of which are key challenges of the upcoming 5G networks. This article not only proposes the fundamentals...

  7. Miniature EVA Software Defined Radio

    Science.gov (United States)

    Pozhidaev, Aleksey

    2012-01-01

    As NASA embarks upon developing the Next-Generation Extra Vehicular Activity (EVA) Radio for deep space exploration, the demands on EVA battery life will substantially increase. The number of modes and frequency bands required will continue to grow in order to enable efficient and complex multi-mode operations including communications, navigation, and tracking applications. Whether conducting astronaut excursions, communicating to soldiers, or first responders responding to emergency hazards, NASA has developed an innovative, affordable, miniaturized, power-efficient software defined radio that offers unprecedented power-efficient flexibility. This lightweight, programmable, S-band, multi-service, frequency- agile EVA software defined radio (SDR) supports data, telemetry, voice, and both standard and high-definition video. Features include a modular design, an easily scalable architecture, and the EVA SDR allows for both stationary and mobile battery powered handheld operations. Currently, the radio is equipped with an S-band RF section. However, its scalable architecture can accommodate multiple RF sections simultaneously to cover multiple frequency bands. The EVA SDR also supports multiple network protocols. It currently implements a Hybrid Mesh Network based on the 802.11s open standard protocol. The radio targets RF channel data rates up to 20 Mbps and can be equipped with a real-time operating system (RTOS) that can be switched off for power-aware applications. The EVA SDR's modular design permits implementation of the same hardware at all Network Nodes concept. This approach assures the portability of the same software into any radio in the system. It also brings several benefits to the entire system including reducing system maintenance, system complexity, and development cost.

  8. THE STUDY OF CHEMICAL COMPOSITION FOR ANIMAL FATS DURING STORAGE

    OpenAIRE

    Flavia Pop; Cornel Laslo

    2009-01-01

    In this article the chemical composition for 3 types of animal fats (pork fat, beef tallow and buffalo tallow), following the variation of saturated and unsaturated fatty acids proportion during freezing storage was studied. Determination of chemical composition of animal fats is important in establishing organoleptic and physico-chemical parameters, the variation of them in time, nature and proportion of fatty acids conferring specific characteristics to them. For pork fat was determined the...

  9. In vivo experiments and numerical investigations on nanocryosurgical freezing of target tissues with large blood vessels.

    Science.gov (United States)

    Sun, Zi-Qiao; Yang, Yang; Liu, Jing

    2012-02-01

    This study presented the first in vivo animal experiments of using nano-cryosurgical modality to completely freezing tumor tissues embedded with large blood vessels, which is a tough issue to tackle otherwise. Three-dimensional theoretical simulations were also performed on the complex freezing problems by considering flow and heat transfer of blood flow in large vessels. According to the experimental measurements and numerical predictions, injecting the nanoparticles with high thermal conductivity into the freezing target can significantly reduce the heating effect of blood vessel, shorten the freezing time, and enlarge the freezing range. Most importantly, the introduction of nanoparticles successfully overcomes the classical challenges in completely ablating the tumor region with large blood vessel and enhancing the freezing efficacy of cryosurgery. This investigation consolidates the practical and theoretical foundation for nano-cryosurgery which suggests a highly efficient freezing strategy for treating late stage tumor.

  10. Cold tolerance and freeze-induced glucose accumulation in three terrestrial slugs

    DEFF Research Database (Denmark)

    Slotsbo, Stine; Hansen, Lars Monrad; Jordaens, Kurt;

    2012-01-01

    in their habitat. Slugs spontaneously froze at about -4 °C when cooled under dry conditions, but freezing of body fluids was readily induced at -1 °C when in contact with external ice crystals. All three species survived freezing for 2 days at -1 °C, and some A. rufus and A. lusitanicus also survived freezing......Cold tolerance and metabolic responses to freezing of three slug species common in Scandinavia (Arion ater, Arion rufus and Arion lusitanicus) are reported. Autumn collected slugs were cold acclimated in the laboratory and subjected to freezing conditions simulating likely winter temperatures....... Glucose increased from about 6 to 22 µg/mg dry tissue upon freezing in A. rufus, but less so in A. ater and A. lusitanicus. Glucose may thus act as a cryoprotectant in these slugs, although the concentrations are not as high as reported for other freeze tolerant invertebrates....

  11. Biological aspects of the DM28C clone of Trypanosoma cruzi after metacylogenesis in chemically defined media Aspectos biológicos do clone Dm 28c de Trypanosoma cruzi após metaciclogênese em meio quimicamente definido

    Directory of Open Access Journals (Sweden)

    Victor T. Contreras

    1988-03-01

    Full Text Available The biological characterization of the Trypanosoma cruzi clone Dm 28c in terms of its growth in LIT medium, cell-cycle, infectivity to mice and interaction with professional and non-professional phagocytic cells shows that it behaves as a bona fide T. cruzi representant. The biological properties of this myotropic clone do not change according to the origin of the trypomastigote forms (i. e., from triatomines, infected mice, cell-culture or from the chemically defined TAUP and TAU3AAG media. In addition Dm 28c metacyclic trypomastigotes from TAU3AAG medium display a high infectivity level to fibroblasts and muscle cells. Experiments on binding of cationized ferritin to trypomastigotes surface show the existence of cap-like structures of ferritin in regions near the kinetoplast. However the nature and role of these anionic sites remain to be determined. The results indicate that metacyclic trypomastigotes from Dm 28c clone obtained under chemically defined conditions reproduce the biological behaviour of T. cruzi, rendering this system very suitable for the study of cell-parasite interactions and for the isolation of trypanosome relevant macromolecules.A caracterização biológica do clone Dm 28c de Trypanosoma cruzi em termos do seu crescimento em meio LIT, ciclo celular, infectividade para camundongos e interação com células fagocíticas profissionais e não-profissionais, mostra que o mesmo comporta-se como um fiel representante da espécie T. cruzi. As propriedades biológicas deste clone miotrópico não mudam de acordo com a proveniência das formas tripomastigotas (i. e., de triatomíneos, de camundongos infectados, de cultura celular ou dos meios quimicamente definidos TAUP e TAU3AAG. Ainda mais, formas tripomastigotas metacíclicas do clone Dm 28c derivado do meio TAU3AAG apresentam um alto grau de infectividade para fibroblastos e células de músculo. Experimentos de ligação de ferritina cationizada à superfície de

  12. CFD modelling of condensers for freeze-drying processes

    Indian Academy of Sciences (India)

    Miriam Petitti; Antonello A Barresi; Daniele L Marchisio

    2013-12-01

    The aim of the present research is the development of a computational tool for investigating condensation processes and equipment with particular attention to freeze-dryers. These condensers in fact are usually operated at very low pressures, making it difficult to experimentally acquire quantitative knowledge of all the variables involved. Mathematical modelling and CFD (Computational Fluid Dynamics) simulations are used here to achieve a better comprehension of the flow dynamics and of the process of ice condensation and deposition in the condenser, in order to evaluate condenser efficiency and gain deeper insights of the process to be used for the improvement of its design. Both a complete laboratory-scale freeze-drying apparatus and an industrial-scale condenser have been investigated in this work, modelling the process of water vapour deposition. Different operating conditions have been considered and the influence exerted by the inert gas as well as other parameters has been investigated.

  13. Deformation mechanism of nanoporous materials upon water freezing and melting

    Science.gov (United States)

    Erko, Maxim; Wallacher, Dirk; Paris, Oskar

    2012-10-01

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

  14. Encapsulation of black carrot juice using spray and freeze drying.

    Science.gov (United States)

    Murali, S; Kar, Abhijit; Mohapatra, Debabandya; Kalia, Pritam

    2015-12-01

    Black carrot juice extracted using pectinase enzyme was encapsulated in three different carrier materials (maltodextrin 20DE, gum arabic and tapioca starch) using spray drying at four inlet temperatures (150, 175, 200 and 225 ℃) and freeze drying at a constant temperature of - 53 ℃ and vacuum of 0.22-0.11 mbar with the constant feed mixture. The products were analyzed for total anthocyanin content, antioxidant activity, water solubility index, encapsulation efficiency and total colour change. For both the drying methods followed in this study, maltodextrin 20DE as the carrier material has proven to be better in retaining maximum anthocyanin and antioxidant activity compared to gum arabic and tapioca starch. The best spray dried product, was obtained at 150 ℃. The most acceptable was the freeze dried product with maximum anthocyanin content, antioxidant activity, water solubility index, encapsulation efficiency and colour change.

  15. Freezing in the presence of disorder: a lattice study

    Science.gov (United States)

    Schmidt, Matthias; Lafuente, Luis; Cuesta, José A.

    2003-07-01

    We investigate the freezing transition in a two-dimensional lattice model of annealed hard squares that are subject to the influence of randomly placed quenched particles of the same size. The latter model is a porous medium. By combining two recent density functional approaches we arrive at a theory for quenched-annealed lattice fluids that treats the quenched particles on the level of their one-body density distribution. We show that this approach yields thermodynamics that compare well with results from treating matrix realizations explicitly and performing subsequent averaging over the disorder. The freezing transition from a fluid to a columnar phase is found to be continuous. On increasing matrix density it shifts towards close packing and vanishes beyond a threshold matrix density.

  16. Freezing in the presence of disorder: a lattice study

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Matthias [Soft Condensed Matter, Debye Institut, Utrecht University, Princetonpln 5, 3584 CC Utrecht (Netherlands); Lafuente, Luis [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganes, Madrid (Spain); Cuesta, Jose A [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, Avenida de la Universidad 30, 28911 Leganes, Madrid (Spain)

    2003-07-16

    We investigate the freezing transition in a two-dimensional lattice model of annealed hard squares that are subject to the influence of randomly placed quenched particles of the same size. The latter model is a porous medium. By combining two recent density functional approaches we arrive at a theory for quenched-annealed lattice fluids that treats the quenched particles on the level of their one-body density distribution. We show that this approach yields thermodynamics that compare well with results from treating matrix realizations explicitly and performing subsequent averaging over the disorder. The freezing transition from a fluid to a columnar phase is found to be continuous. On increasing matrix density it shifts towards close packing and vanishes beyond a threshold matrix density.

  17. THE INFLUENCE OF FREEZING ON THE BIOLOGICAL VALUE OF BERRIES

    Directory of Open Access Journals (Sweden)

    MÁRIA NÉMETH- BALOGH

    2013-07-01

    Full Text Available The objective of our research was to observe the influence of freezing on the biological value of selected berry samples according to their antiradical activity, content of anthocyans and vitamin C. The content of vitamin C (method by Lásztity and Törley, 1987, anthocyans (method by Fuleki and Francis, 1968 and antiradical activity (method by Brand- Williams et al., 1995 and Sanchéz- Moreno et al., 1998 were analysed both in frozen and fresh berry samples. In general, the avarage contents of vitamin C, anthocyans and values of antiradical activity in the fresh and frozen berry samples are not significantly different. Freezing of fresh plant materials to –18 °C is suitable for preservation of their basic biological properties (content of anthocyans, vitamin C and antiradical activity. These plant materials can be used for direct consumption and also to rise the biological value of human nutrition.

  18. Preventing freezing of condensate inside tubes of air cooled condenser

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Jeong A; Hwang, In Hwan; Lee, Dong Hwan [Chonbuk Nat' l Univ., Jeonju (Korea, Republic of); Cho, Young Il [Drexel Univ., Philadelphia (United States)

    2012-08-15

    An air cooled condenser is a device that is used for converting steam into condensate by using ambient air. The air cooled condenser is prone to suffer from a serious explosion when the condensate inside the tubes of a heat exchanger is frozen; in particular, tubes can break during winter. This is primarily due to the structural problem of the tube outlet of an existing conventional air cooled condenser system, which causes the backflow of residual steam and noncondensable gases. To solve the backflow problem in such condensers, such a system was simulated and a new system was designed and evaluated in this study. The experimental results using the simulated condenser showed the occurrence of freezing because of the backflow inside the tube. On the other hand, no backflow and freezing occurred in the advanced new condenser, and efficient heat exchange occurred.

  19. Chitosan nanofibers fabricated by combined ultrasonic atomization and freeze casting.

    Science.gov (United States)

    Wang, Yihan; Wakisaka, Minato

    2015-05-20

    Aligned chitosan nanofibers exhibiting diameters smaller than 100 nm were easily prepared by combining ultrasonic atomization with freeze casting. A major advantage of this approach is the use of distilled water as main solvent. Scanning electron microscopy demonstrated that fiber diameter and morphology mainly depended on the atomizing tools, freezing temperature, and chitosan solution viscosity. Minimum diameter and uniform orientation were achieved using an electric flosser as an atomizing tool, liquid nitrogen as a coolant, 0.4 wt% aqueous chitosan solution (molecular weight = 22 kDa), and a small amount of lactic acid as solvent at 0 °C. The resulting chitosan nanofibers may find application in biomedical and food engineering. Moreover, this new technology may be applicable to other natural and synthetic water-soluble polymers.

  20. Heterogeneous ice nucleation: bridging stochastic and singular freezing behavior

    Directory of Open Access Journals (Sweden)

    D. Niedermeier

    2011-01-01

    Full Text Available Heterogeneous ice nucleation, a primary pathway for ice formation in the atmosphere, has been described alternately as being stochastic, in direct analogy with homogeneous nucleation, or singular, with ice nuclei initiating freezing at deterministic temperatures. We present an idealized model that bridges these stochastic and singular descriptions of heterogeneous ice nucleation. This "soccer ball" model treats statistically similar particles as being covered with surface sites (patches of finite area characterized by different nucleation barriers, but with each surface site following the stochastic nature of ice embryo formation. The model provides a phenomenological explanation for seemingly contradictory experimental results obtained in our research groups. We suggest that ice nucleation is fundamentally a stochastic process but that for realistic atmospheric particle populations this process can be masked by the heterogeneity of surface properties. Full evaluation of the model will require experiments with well characterized ice nucleating particles and the ability to vary both temperature and waiting time for freezing.

  1. INFLUENCE OF CYCLIC FREEZING AND THAWING UPON SPRUCE WOOD PROPERTIES

    Directory of Open Access Journals (Sweden)

    Maria Bernadett SZMUTKU

    2012-03-01

    Full Text Available The paper presents the results concerning the change of some physical and mechanical properties of spruce wood (Picea abies L., after repeated freezing and thawing, respectively after being subjected to temperature variation from positive valuea (+100C to negative values (-250C. Through this approach, the authors aimed at simulating normal temperature variations that occur in winter between night and daytime and which fresh cut timber has to stand if being stored in an open yard for one week before being kilndried. By comparing these results with the ones obtained after continuous freezing at -250C for one week, it was established that the temperature variation and the repeated changing phase of water inside wood increase dimensional instability and reduce the mechanical strengths much more than the simple exposure to theconstant negative temperature.

  2. Study on Semen Freezing Preservation of German Shepherd Dogs

    Institute of Scientific and Technical Information of China (English)

    Huang He; Tian Ya-guang; Zheng Peng; Zhang Gui-xue

    2012-01-01

    In order to prolong semen preservation and improve pregnancy rate, semen freezing was studied with German shepherd dogs for experimental animals. The semen of four dogs was collected 40 times in four dilution frozen into two formulations, according to the sperm motility to compare the advantages and disadvantages. The result indicated that the sperm motility of the pellet frozen semen in dilute 2 was significantly higher than that in dilution 1, 3, and 4 (P0.01). The sperm motility of dogs semen with fried smoked method was notablely higher than that of frozen semen of program method (P0.01). The dilution which contained yolk-Tris mainly was the best; the pellet semen frozen with fried smoked method was superior to tuble semen frozen with program freezing method; sperm motility of pellet semen was higher than that of tuble semen in the same dilution. The conception rate and litter size of the natural matting were higher than AI.

  3. Large tundra methane burst during onset of freezing

    DEFF Research Database (Denmark)

    Mastepanov, Mikhail; Sigsgaard, Charlotte; Dlugokencky, Edward J.;

    2008-01-01

    Terrestrial wetland emissions are the largest single source of the greenhouse gas methane1. Northern high-latitude wetlands contribute significantly to the overall methane emissions from wetlands, but the relative source distribution between tropical and high-latitude wetlands remains uncertain2...... after the growing season but then increase significantly during the freeze-in period. The integral of emissions during the freeze-in period is approximately equal to the amount of methane emitted during the entire summer season. Three-dimensional atmospheric chemistry and transport model simulations......,3. As a result, not all the observed spatial and seasonal patterns of atmospheric methane concentrations can be satisfactorily explained, particularly for high northern latitudes. For example, a late-autumn shoulder is consistently observed in the seasonal cycles of atmospheric methane at high-latitude sites4...

  4. Barium titanate-polymer composites produced via directional freezing.

    Science.gov (United States)

    Gorzkowski, Edward P; Pan, Ming-Jen

    2009-08-01

    In this study, we use a freeze casting technique to construct ceramic-polymer composites in which the 2 phases are arranged in an electrically parallel configuration. By doing so, the composites exhibit dielectric constant (K) up to 2 orders of magnitude higher than that of composites with ceramic particles randomly dispersed in a polymer matrix. In this technique, an aqueous ceramic slurry was frozen unidirectionally to form ice platelets and ceramic aggregates that were aligned in the temperature gradient direction. Upon freeze-drying, the ice platelets sublimed and left the lamellar ceramic structure intact. The green ceramic body was fired to retain the microstructure, and then the space between ceramic lamellae was infiltrated with a polymer material. The finished composites exhibit the high dielectric constant (1000) of ferroelectric ceramics while maintaining the unique properties of polymer materials such as graceful failure, low dielectric loss, and high dielectric breakdown.

  5. Characterization of freeze dried egg melange long stored after irradiation

    Science.gov (United States)

    Bakalivanov, Stefan; Tsvetkova, Eli; Bakalivanova, Todorka; Tsvetkov, Tsvetan; Kaloyanov, Nikolay; Grigorova, Stoyanka; Alexieva, Vanja

    2008-01-01

    During the 4-year period of storage at room temperature of the freeze-dried (control group) and the freeze-dried and gamma-irradiated (2.0 and 3.5 kGy) whole hen's egg mélange, no significant changes were found into the sensory and functional characteristics till the 28th month. The change in the number of SH groups was not unidirectional up to the 28th month and then it started to decrease in all investigated samples. During the entire period of investigation the amount of malondialdehyde in all three groups of egg mélange was considerably below the allowed limit for foodstuffs. The most significant fractions of the protein spectra showed a general tendency of decrease during the storage.

  6. Freeze/thaw phenomena in concrete at low temperatures

    DEFF Research Database (Denmark)

    Johannesson, Björn

    2007-01-01

    Freeze/thaw damage in concrete is by general practice concluded to be a problem that can be avoided by using air-entraining agents to develop an air bubble structure in the hardened concrete together with the use of a relatively low water to cement ratio in mix. This fact is true for inner damages......, however, the so-called salt-frost damage, occurring mainly at the surfaces of concrete constructions, can not totally be avoided by the above mentioned method. The performance and the mechanisms occurring in concrete, with a substantial amount of water in its micro-structure, at very low temperature are......, however, in most part unknown. In this work samples of concrete at different water to cement ratios and air bubble contents subjected to freeze/thaw cycles with the lowest temperature at about -80 oC are investigated. By adopting a novel technique a scanning calorimeter is used to obtain data from which...

  7. Promising freeze protection alternatives in solar domestic hot water systems

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, D.E.

    1997-12-31

    Since the gains associated with solar thermal energy technologies are comparatively small in relation to the required capital investment, it is vital to maximize conversion efficiency. While providing the necessary function of freeze protection, the heat exchanger commonly included in solar domestic water heating systems represents a system inefficiency. This thesis explores two alternate methods of providing freeze protection without resorting to a heat exchanger. Commonly, collectors are made of rigid copper tubes separated by copper or aluminum fins. Cracking damage can occur when water is allowed to freeze and expand inside the non compliant tubes. The possibility of making collectors out of an elastic material was investigated and shown to be effective. Since unlike copper, elastomers typically have low thermal conductivities, the standard collector performance prediction equations do not apply. Modified thermal performance prediction equations were developed which can be used for both low and high thermal conductivity materials to provide accurate predictions within a limited range of plate geometries. An elastomeric collector plate was then designed and shown to have comparable performance to a copper plate collector whose aperture area is approximately 33% smaller. Another options for providing freeze protection to an SDHW system is to turn it off during the winter. Choosing a three-season operating period means two things. First, the system will have different optimums such as slope and collector area. Second, the wintertime solar energy incident on the collector is unavailable for meeting a heating load. However, the system`s heat exchanger becomes unnecessary and removing it increases the amount of energy that arrives at the storage tank during those periods in which the system is operating.

  8. Market run-ups, market freezes, and leverage

    OpenAIRE

    Philip Bond; Yaron Leitner

    2010-01-01

    The authors study trade between a buyer and a seller when both may have existing inventories of assets similar to those being traded. They analyze how these inventories affect trade, information dissemination, and price formation. The authors show that when the buyer's and seller's initial leverage is moderate, inventories increase price and trade volume, but when leverage is high, trade may become impossible (a "market freeze"). Their analysis predicts a pattern of trade in which prices and ...

  9. 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.

  10. Freeze-Spray Processing of Layered Ceramic Composites (Preprint)

    Science.gov (United States)

    2006-04-01

    remove the ice by sublimation . In order to study the effect of green density on the sintered microstructure, a set of samples were isostatically...Ceram. Forum Int., 79 ( 9 , E35-E38, (2002). ’K. Araki and J. W. Halloran, "Room-Temperature Freeze Casting for Ceramics with Nonaqueous Sublimable ...Vehicles in the Naphtalene- Camphor Eutectic System," J. Am. Cerum Soc. 87 (1 1) 2014-2019 (2004). 9 ~ . Reed, Introduction to the Principles of

  11. Synthesis and structural evaluation of freeze-cast porous alumina

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Douglas F., E-mail: souzadf@outlook.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nunes, Eduardo H.M., E-mail: eduardohmn@gmail.com [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Pimenta, Daiana S.; Vasconcelos, Daniela C.L. [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil); Nascimento, Jailton F.; Grava, Wilson [Petrobras/CENPES, Avenida Horácio Macedo 950, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ CEP:21941-915 (Brazil); Houmard, Manuel [Department of Materials Engineering and Civil Construction, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 1, sala 3304 (Brazil); Vasconcelos, Wander L., E-mail: wlv@demet.ufmg.br [Department of Metallurgical and Materials Engineering, Federal University of Minas Gerais — UFMG, Avenida Presidente Antônio Carlos, 6627, Campus UFMG, Belo Horizonte, MG CEP: 31270-901, Escola de Engenharia, bloco 2, sala 2230 (Brazil)

    2014-10-15

    In this work we fabricated alumina samples by the freeze-casting technique using tert-butanol as the solvent. The prepared materials were examined by scanning electron microscopy and X-ray microtomography. Next, they were coated with sol–gel silica films by dip-coating. Permeability tests were carried out in order to assess the permeation behavior of the materials processed in this study. We observed that the sintering time and alumina loading showed a remarkable effect on both the structural properties and flexural strength of the freeze-cast samples. Nitrogen adsorption tests revealed that the silica prepared in this study exhibited a microporous structure. It was observed that the presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance by about one order of magnitude. Because of the similar kinetic diameters of nitrogen and carbon dioxide, the CO{sub 2}/N{sub 2} system showed a separation efficiency that was lower than that observed for the He/CO{sub 2} and He/N{sub 2} systems. We noticed that increasing the feed pressure improved the separation capacity of the obtained materials. - Highlights: • Porous alumina samples obtained by the freeze-casting technique • Microporous silica coating prepared by a simple sol–gel dip-coating methodology • Samples examined by SEM, μ-CT, and nitrogen sorption tests • Mechanical tests were carried out in the freeze-cast samples. • The presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance.

  12. Promising freeze protection alternatives in solar domestic hot water systems

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, David E. [Univ. of Wisconsin, Madison, WI (United States)

    1997-01-01

    Since the gains associated with solar thermal energy technologies are comparatively small in relation to the required capital investment, it is vital to maximize conversion efficiency. While providing the necessary function of freeze protection, the heat exchanger commonly included in solar domestic water heating systems represents a system inefficiency. This thesis explores two alternate methods of providing freeze protection without resorting to a heat exchanger. Commonly, collectors are made of rigid copper tubes separated by copper or aluminum fins. Cracking damage can occur when water is allowed to freeze and expand inside the non compliant tubes. The possibility of making collectors out of an elastic material was investigated and shown to be effective. Since unlike copper, elastomers typically have low thermal conductivities, the standard collector performance prediction equations do not apply. Modified thermal performance prediction equations were developed which can be used for both low and high thermal conductivity materials to provide accurate predictions within a limited range of plate geometries. An elastomeric collector plate was then designed and shown to have comparable performance to a copper plate collector whose aperture area is approximately 33% smaller. Another options for providing freeze protection to an SDHW system is to turn it off during the winter. Choosing a three-season operating period means two things. First, the system will have different optimums such as slope and collector area. Second, the wintertime solar energy incident on the collector is unavailable for meeting a heating load. However, the system`s heat exchanger becomes unnecessary and removing it increases the amount of energy that arrives at the storage tank during those periods in which the system is operating.

  13. Monitoring Winter Wheat Freeze Injury Using Multi-Temporal MODIS Data

    Institute of Scientific and Technical Information of China (English)

    FENG Mei-chen; YANG Wu-de; CAO Liang-liang; DING Guang-wei

    2009-01-01

    Freeze injury is an usual disaster for winter wheat in Shanxi Province,China,and monitoring freeze injury is of important economic significance.The aim of this article is to monitor and analyze the winter wheat freeze injury using remote sensmg data,to monitor the occurrence and spatial distribution of winter wheat freeze in time.as well as the severity of the damage.The winter wheat freeze injury was monitored using multi-temporal moderate-resolution imaging spectroradiometer (MODIS) data,combined with ground meteorological data and field survey data,the change of normalized difference vegetation index (NDVI) before and after freeze injury was analyzed,as well as the effect of winter wheat growth recovery rate on yield.The results showed that the NDVI of winter wheat decreased dramatically after the suffering from freeze injury,which was the prominent feature for the winter wheat freeze injury monitoring.The degrees of winter wheat freeze injury were different in the three regions,of which,Yuncheng was the worst severity and the largest freeze injury area,the severity of freeze injury correlates with the breeding stage of the winter wheat.The yield of winter wheat showed positive correlation with its growth recovery rate (r=0.659**) which can be utilized to monitor the severity of winter wheat freeze injury as well as its impact on yield.It can effectively monitor the occurrence and severity of winter wheat freeze injury using horizontal and vertical profile distribution and growth recovery rate,and provide a basis for monitoring the winter wheat freeze injury in Shanxi Province.

  14. Recent changes in the frequency of freezing precipitation in North America and Northern Eurasia

    Science.gov (United States)

    Groisman, Pavel Ya; Bulygina, Olga N.; Yin, Xungang; Vose, Russell S.; Gulev, Sergey K.; Hanssen-Bauer, Inger; Førland, Eirik

    2016-04-01

    Freezing rain and freezing drizzle events represent a critical feature of many regions of the world. Even at low intensities, these events often result in natural hazards that cause damage to housing, communication lines, and other man-made infrastructure. These events usually occur near the 0 °C isotherm. In a changing climate, this isotherm will not disappear, but its position in space and time will likely change as will the geography of freezing precipitation. A larger influx of water vapor into the continents from the oceans may also increase the amount and frequency of freezing precipitation events. This paper assesses our current understanding of recent changes in freezing precipitation for the United States, Canada, Norway, and Russia. The research is part of a larger GEWEX Cross-Cut Project addressing ‘cold/shoulder season precipitation near 0 °C’. Using an archive of 874 long-term time series (40 years of data) of synoptic observations for these four countries, we document the climatology of daily freezing rain and freezing drizzle occurrences as well as trends therein. The regions with the highest frequency of freezing rains (from 3 to 8 days per year) reside in the northeastern quadrant of the conterminous United States and adjacent areas of southeastern Canada south of 50 °N and over the south and southwest parts of the Great East European Plain. The frequency of freezing drizzle exceeds the frequency of freezing rain occurrence in all areas. During the past decade, the frequency of freezing rain events somewhat decreased over the southeastern US. In North America north of the Arctic Circle, it increased by about 1 day yr-1. Over Norway, freezing rain occurrences increased substantially, especially in the Norwegian Arctic. In European Russia and western Siberia, the frequency of freezing rain somewhat increased (except the southernmost steppe regions and the Arctic regions) while freezing drizzle frequency decreased over entire Russia.

  15. Moisture sorption characteristics of freeze-dried human platelets

    Institute of Scientific and Technical Information of China (English)

    Meng-jie XU; Guang-ming CHEN; Ju-li FAN; Jin-hui LIU; Xian-guo XU; Shao-zhi ZHANG

    2011-01-01

    Freeze-drying is a promising method for a long-term storage of human platelets. The moisture sorption characteristics of freeze-dried human platelets (FDHPs) were studied in this paper. The moisture sorption isotherms of FDHPs and freeze-dried lyophilization buffer (FDLB) were measured at 4, 25, and 37 ℃. The experimental data were fitted to Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) equations. There were no significant statistical differences (P>0.05) between the sorption characteristics of FDHPs and FDLB at 4 and 25 ℃, while FDHPs absorbed more water at 37 ℃. The net isosteric heat of sorption was derived. The heat for FDHPs showed an abnormal negative value at low moisture contents when 25 and 37 ℃ data were used. Dynamic sorption experiments were carried out at 25 ℃ with environmental water activity controlled at 0.75, 0.85, and 0.90. The moisture diffusion coefficient was fitted to be 8.24x 10-12 m2/s when experimental data at initial time were used. These results would be helpful in choosing prehydration and storage condition for FDHPs.

  16. Antifreeze proteins enable plants to survive in freezing conditions

    Indian Academy of Sciences (India)

    Ravi Gupta; Renu Deswal

    2014-12-01

    Overwintering plants secrete antifreeze proteins (AFPs) to provide freezing tolerance. These proteins bind to and inhibit the growth of ice crystals that are formed in the apoplast during subzero temperatures. Antifreeze activity has been detected in more than 60 plants and AFPs have been purified from 15 of these, including gymnosperms, dicots and monocots. Biochemical characterization of plant antifreeze activity, as determined by the high ice recrystallization inhibition (IRI) activities and low thermal hysteresis (TH) of AFPs, showed that their main function is inhibition of ice crystal growth rather than the lowering of freezing temperatures. However, recent studies showed that antifreeze activity with higher TH also exists in plants. Calcium and hormones like ethylene and jasmonic acid have been shown to regulate plant antifreeze activity. Recent studies have shown that plant AFPs bind to both prism planes and basal planes of ice crystals by means of two flat ice binding sites. Plant AFPs have been postulated to evolve from the OsLRR-PSR gene nearly 36 million years ago. In this review, we present the current scenario of plant AFP research in order to understand the possible potential of plant AFPs in generation of freezing-tolerant crops.

  17. Warm and cold fermionic dark matter via freeze-in

    CERN Document Server

    Klasen, Michael

    2013-01-01

    The freeze-in mechanism of dark matter production provides a simple and intriguing alternative to the WIMP paradigm. In this paper, we analyze whether freeze-in can be used to account for the dark matter in the so-called singlet fermionic model. In it, the SM is extended with only two additional fields, a singlet scalar that mixes with the Higgs boson, and the dark matter particle, a fermion assumed to be odd under a Z_2 symmetry. After numerically studying the generation of dark matter, we analyze the dependence of the relic density with respect to all the free parameters of the model. These results are then used to obtain the regions of the parameter space that are compatible with the dark matter constraint. We demonstrate that the observed dark matter abundance can be explained via freeze-in over a wide range of masses extending down to the keV range. As a result, warm and cold dark matter can be obtained in this model. It is also possible to have dark matter masses well above the unitarity bound for WIMPs...

  18. Warm and cold fermionic dark matter via freeze-in

    Science.gov (United States)

    Klasen, Michael; Yaguna, Carlos E.

    2013-11-01

    The freeze-in mechanism of dark matter production provides a simple and intriguing alternative to the WIMP paradigm. In this paper, we analyze whether freeze-in can be used to account for the dark matter in the so-called singlet fermionic model. In it, the SM is extended with only two additional fields, a singlet scalar that mixes with the Higgs boson, and the dark matter particle, a fermion assumed to be odd under a Z2 symmetry. After numerically studying the generation of dark matter, we analyze the dependence of the relic density with respect to all the free parameters of the model. These results are then used to obtain the regions of the parameter space that are compatible with the dark matter constraint. We demonstrate that the observed dark matter abundance can be explained via freeze-in over a wide range of masses extending down to the keV range. As a result, warm and cold dark matter can be obtained in this model. It is also possible to have dark matter masses well above the unitarity bound for WIMPs.

  19. Warm and cold fermionic dark matter via freeze-in

    Energy Technology Data Exchange (ETDEWEB)

    Klasen, Michael; Yaguna, Carlos E., E-mail: michael.klasen@uni-muenster.de, E-mail: carlos.yaguna@uni-muenster.de [Institut für Theoretische Physik, Universität Münster, Wilhelm-Klemm-Straße 9, D-48149 Münster (Germany)

    2013-11-01

    The freeze-in mechanism of dark matter production provides a simple and intriguing alternative to the WIMP paradigm. In this paper, we analyze whether freeze-in can be used to account for the dark matter in the so-called singlet fermionic model. In it, the SM is extended with only two additional fields, a singlet scalar that mixes with the Higgs boson, and the dark matter particle, a fermion assumed to be odd under a Z{sub 2} symmetry. After numerically studying the generation of dark matter, we analyze the dependence of the relic density with respect to all the free parameters of the model. These results are then used to obtain the regions of the parameter space that are compatible with the dark matter constraint. We demonstrate that the observed dark matter abundance can be explained via freeze-in over a wide range of masses extending down to the keV range. As a result, warm and cold dark matter can be obtained in this model. It is also possible to have dark matter masses well above the unitarity bound for WIMPs.

  20. Fluid Line Evacuation and Freezing Experiments for Digital Radiator Concept

    Science.gov (United States)

    Berisford, Daniel F.; Birur, Gajanana C.; Miller, Jennifer R.; Sunada, Eric T.; Ganapathi, Gani B.; Stephan, Ryan; Johnson, Mark

    2011-01-01

    The digital radiator technology is one of three variable heat rejection technologies being investigated for future human-rated NASA missions. The digital radiator concept is based on a mechanically pumped fluid loop with parallel tubes carrying coolant to reject heat from the radiator surface. A series of valves actuate to start and stop fluid flow to di erent combinations of tubes, in order to vary the heat rejection capability of the radiator by a factor of 10 or more. When the flow in a particular leg is stopped, the fluid temperature drops and the fluid can freeze, causing damage or preventing flow from restarting. For this reason, the liquid in a stopped leg must be partially or fully evacuated upon shutdown. One of the challenges facing fluid evacuation from closed tubes arises from the vapor generated during pumping to low pressure, which can cause pump cavitation and incomplete evacuation. Here we present a series of laboratory experiments demonstrating fluid evacuation techniques to overcome these challenges by applying heat and pumping to partial vacuum. Also presented are results from qualitative testing of the freezing characteristics of several different candidate fluids, which demonstrate significant di erences in freezing properties, and give insight to the evacuation process.

  1. Tuning towards dynamic freezing using a two-rate protocol

    Science.gov (United States)

    Kar, Satyaki; Mukherjee, Bhaskar; Sengupta, K.

    2016-08-01

    We study periodically driven closed quantum systems where two parameters of the system Hamiltonian are varied periodically in time with frequencies ω1 and ω2=r ω1 . We show that such drives may be used to tune towards dynamics-induced freezing where the wave function of the state of the system after a drive cycle at time T =2 π /ω1 has almost perfect overlap with the initial state. We locate regions in the (ω1,r ) plane where the freezing is near exact for a class of integrable models and a specific nonintegrable model. The integrable models that we study encompass Ising and XY models in d =1 , Kitaev model in d =2 , and Dirac fermions in graphene and atop a topological insulator surface, whereas the nonintegrable model studied involves the experimentally realized one-dimensional tilted Bose-Hubbard model in an optical lattice. In addition, we compute the relevant correlation functions of such driven systems and describe their characteristics in the region of the (ω1,r ) plane where the freezing is near exact. We supplement our numerical analysis with semianalytic results for integrable driven systems within adiabatic-impulse approximation and discuss experiments which may test our theory.

  2. A Comparison of Thawing and Freezing Dark Energy Parametrizations

    CERN Document Server

    Pantazis, G; Perivolaropoulos, L

    2016-01-01

    Dark energy equation of state $w(z)$ parametrizations with two parameters and given monotonicity are generically either convex or concave functions. This makes them suitable for fitting either freezing or thawing quintessence models but not both simultaneously. Fitting a dataset based on a freezing model with an unsuitable (concave when increasing) $w(z)$ parametrization (like CPL) can lead to significant misleading features like crossing of the phantom divide line, incorrect $w(z=0)$, incorrect slope \\etc that are not present in the underlying cosmological model. To demonstrate this fact we generate scattered cosmological data both at the level of $w(z)$ and the luminosity distance $D_L(z)$ based on either thawing or freezing quintessence models and fit them using parametrizations of convex and of concave type. We then compare statistically significant features of the best fit $w(z)$ with actual features of the underlying model. We thus verify that the use of unsuitable parametrizations can lead to misleadin...

  3. Preparation and Characterization of Directionally Freeze-cast Copper Foams

    Directory of Open Access Journals (Sweden)

    Aurelia I. Cuba Ramos

    2012-08-01

    Full Text Available Because of their excellent thermal and electric conductivities, copper foams are ideally suited for applications such as heat exchangers, catalyst supports and EMI-shields. Here, we demonstrate the preparation of copper with ~80% aligned, elongated, interconnected pores via directional freeze casting, a well established processing technique for porous ceramics. First, an aqueous slurry of 40−80 nm cupric oxide powders was directionally solidified, resulting in a preform consisting of elongated, aligned dendrites of pure ice separated by interdendritic ice walls with high oxide powder content. Oxide rather than metallic nanometric particles are used, as the latter would oxidize rapidly and uncontrollably when suspended in the aqueous solution used during directional casting. The preforms were then freeze-dried to sublimate the ice and sintered in a hydrogen-bearing atmosphere to reduce the copper oxide to metallic copper particles and densify these copper particles. Microstructural analysis of the copper foams shows that three types of porosities are present: (i aligned, elongated pores replicating the ice dendrites created during the freeze-casting process; (ii micro-porosity in the partially sintered copper walls separating the elongated pores; and (iii cracks in these copper walls, probably created because of shrinkage associated with the reduction of the oxide powders.

  4. On the transition between heterogeneous and homogeneous freezing

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2002-12-01

    Full Text Available Box model simulations of an uplifting and adiabatically cooling cloud of aerosol have been performed in order to study the transition between cirrus formation dominated by homogeneous nucleation of ice to that dominated by heterogeneous nucleation. The aerosol was assumed to consist of an internal mixture of sulfuric acid solution droplets with inclusions of soot. The simulations show that the transition from heterogeneous to homogeneous nucleation occurs over a narrow range of soot concentration. Thus it seems to be possible to fix critical concentrations of heterogeneous ice nuclei which must be exceeded if heterogeneous freezing dominates cirrus formation. A formula has been derived that allows to compute the critical concentrations of heterogeneous ice nuclei as a function of temperature, updraft speed, ambient pressure, and supersaturation at which heterogeneous freezing occurs. Generally, homogeneous nucleation dominates in regions with updrafts stronger than 20 cmps, with the exception of heavily polluted areas which could be common in the northern hemisphere due to air traffic, where updrafts of the order 1 mps may be necessary to render heterogeneous nucleation unimportant. According to the present results it cannot be excluded that heterogeneous nucleation plays a more important role for cirrus formation in the northern midlatitudes than anywhere else. A possible consequence of these results is that air pollution may lead to a higher coverage of cirrus clouds, but then these clouds will be optically thinner than clouds formed by homogeneous freezing, with the exception of regions where condensation trails are frequent.

  5. Software Defined Common Processing System (SDCPS) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Coherent Logix, Incorporated proposes the Software Defined Common Processing System (SDCPS) program to facilitate the development of a Software Defined Radio...

  6. Development of Spalangia cameroni and Muscidifurax raptor (Hymenoptera: Pteromalidae) on Live and Freeze-killed House Fly (Diptera: Muscidae) Pupae

    Science.gov (United States)

    This study was conducted to determine if the reduced suitability of freeze-killed pupae for Pteromalidae, particularly Spalangia cameroni Perkins, is due to freezing, freezing duration or the type of freezer utilized. Processing pupae through freezing had a considerably greater negative effect on ...

  7. Suitability of a Freeze Dried Product as a Vehicle for Vitamin Fortification of Military Ration Packs: A Preliminary Study

    Science.gov (United States)

    2011-01-01

    loaded into the freeze dryer and dried over an eight hour period. The freeze dried product was removed from the freeze dryer and transferred to...plastic bags (one bag per treatment). While in the bag the pieces of freeze dried product were manually broken and tumbled to mix. The bags were placed

  8. Studies of heterogeneous freezing by three different desert dust samples

    Directory of Open Access Journals (Sweden)

    P. J. Connolly

    2009-01-01

    Full Text Available We present results of experiments at the aerosol interactions and dynamics in the atmosphere (AIDA chamber facility looking at the freezing of water by three different types of mineral particles at temperatures between −12°C and −33°C. The three different dusts are Asia Dust-1 (AD1, Sahara Dust-2 (SD2 and Arizona test Dust (ATD. The dust samples used had particle concentrations of sizes that were log-normally distributed with mode diameters between 0.3 and 0.5 μm and standard deviations, σg, of 1.6–1.9. The results from the freezing experiments are consistent with the singular hypothesis of ice nucleation. The dusts showed different nucleation abilities, with ATD showing a rather sharp increase in ice-active surface site density at temperatures less than −24°C. AD1 was the next most efficient freezing nuclei and showed a more gradual increase in activity than the ATD sample. SD2 was the least active freezing nuclei.

    We used data taken with particle counting probes to derive the ice-active surface site density forming on the dust as a function of temperature for each of the three samples and polynomial curves are fitted to this data. The curve fits are then used independently within a bin microphysical model to simulate the ice formation rates from the experiments in order to test the validity of parameterising the data with smooth curves. Good agreement is found between the measurements and the model for AD1 and SD2; however, the curve for ATD does not yield results that agree well with the observations. The reason for this is that more experiments between −20 and −24°C are needed to quantify the rather sharp increase in ice-active surface site density on ATD in this temperature regime. The curves presented can be used as parameterisations in atmospheric cloud models where cooling rates of approximately 1°C min−1 or more are present to predict the concentration of ice crystals forming by

  9. Studies of heterogeneous freezing by three different desert dust samples

    Directory of Open Access Journals (Sweden)

    P. J. Connolly

    2009-04-01

    Full Text Available We present results of experiments at the aerosol interactions and dynamics in the atmosphere (AIDA chamber facility looking at the freezing of water by three different types of mineral particles at temperatures between −12°C and −33°C. The three different dusts are Asia Dust-1 (AD1, Sahara Dust-2 (SD2 and Arizona test Dust (ATD. The dust samples used had particle concentrations of sizes that were log-normally distributed with mode diameters between 0.3 and 0.5 μm and standard deviations, σg, of 1.6–1.9. The results from the freezing experiments are consistent with the singular hypothesis of ice nucleation. The dusts showed different nucleation abilities, with ATD showing a rather sharp increase in ice-active surface site density at temperatures less than −24°C. AD1 was the next most efficient freezing nuclei and showed a more gradual increase in activity than the ATD sample. SD2 was the least active freezing nuclei.

    We used data taken with particle counting probes to derive the ice-active surface site density forming on the dust as a function of temperature for each of the three samples and polynomial curves are fitted to this data. The curve fits are then used independently within a bin microphysical model to simulate the ice formation rates from the experiments in order to test the validity of parameterising the data with smooth curves. Good agreement is found between the measurements and the model for AD1 and SD2; however, the curve for ATD does not yield results that agree well with the observations. The reason for this is that more experiments between −20 and −24°C are needed to quantify the rather sharp increase in ice-active surface site density on ATD in this temperature regime. The curves presented can be used as parameterisations in atmospheric cloud models where cooling rates of approximately 1°C min−1 or more are present to predict the concentration of ice crystals forming by the

  10. Freeze-In dark matter with displaced signatures at colliders

    Energy Technology Data Exchange (ETDEWEB)

    Co, Raymond T.; D’Eramo, Francesco; Hall, Lawrence J.; Pappadopulo, Duccio [Berkeley Center for Theoretical Physics, Department of Physics,and Theoretical Physics Group, Lawrence Berkeley National Laboratory,University of California,Berkeley, CA 94720 (United States)

    2015-12-11

    Dark matter, X, may be generated by new physics at the TeV scale during an early matter-dominated (MD) era that ends at temperature T{sub R}≪ TeV. Compared to the conventional radiation-dominated (RD) results, yields from both Freeze-Out and Freeze-In processes are greatly suppressed by dilution from entropy production, making Freeze-Out less plausible while allowing successful Freeze-In with a much larger coupling strength. Freeze-In is typically dominated by the decay of a particle B of the thermal bath, B→X. For a large fraction of the relevant cosmological parameter space, the decay rate required to produce the observed dark matter abundance leads to displaced signals at LHC and future colliders, for any m{sub X} in the range keV

  11. Freezing of bentonite. Experimental studies and theoretical considerations

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2010-01-15

    During its lifetime, a KBS-3 repository will be subject to various ambient temperatures. Backfilled tunnels, shafts and investigation bore holes closest to ground level will experience periods of temperature below 0 deg C. From a safety assessment perspective, it is therefore essential to understand the behavior of compacted bentonite below 0 deg C. A theoretical framework for predicting the pressure response in compacted water saturated bentonite due to temperature changes has been developed based on thermodynamics and a single pore-type. This model predicts an approximately linear temperature dependence of swelling pressure P{sub s}(w,DELTAT) = P{sub s}(w,0 deg C) + DELTAs(w)DELTAT/nu{sub clay}(w) where DELTAT denotes a temperature difference from 0 deg C, DELTAs(w) is the difference in partial molar entropy between clay water and bulk water, nu{sub clay} (w) is the partial molar volume of the clay water and w denotes the water/solid mass ratio of the clay. As bulk water changes phase at 0 deg C, DELTAs(w) has a different value dependent on whether DELTAT is negative or positive. Above 0 deg C DELTAs(w) is a small value for all relevant densities which means that the pressure response due to temperature changes is small. A further consequence of this fact is that DELTAs(w) is a large positive number below 0 deg C when the external water phase is transformed to ice. Consequently, the model predicts a large drop of swelling pressure with temperature below 0 deg C, in the order of 1.2 MPa/deg C. Specifically, the swelling pressure is zero at a certain (negative) temperature T{sub C}. T{sub C} also quantifies the freezing point of the bentonite sample under consideration, as ice formation in the bentonite does not occur until swelling pressure is lost. A large set of laboratory tests have been performed where fully water saturated samples of bentonites have been exposed to temperatures in the range -10 deg C to +25 deg C. The swelling pressure response has been

  12. Freezing of bentonite. Experimental studies and theoretical considerations

    Energy Technology Data Exchange (ETDEWEB)

    Birgersson, Martin; Karnland, Ola; Nilsson, Ulf (Clay Technology AB, Lund (Sweden))

    2010-01-15

    During its lifetime, a KBS-3 repository will be subject to various ambient temperatures. Backfilled tunnels, shafts and investigation bore holes closest to ground level will experience periods of temperature below 0 deg C. From a safety assessment perspective, it is therefore essential to understand the behavior of compacted bentonite below 0 deg C. A theoretical framework for predicting the pressure response in compacted water saturated bentonite due to temperature changes has been developed based on thermodynamics and a single pore-type. This model predicts an approximately linear temperature dependence of swelling pressure P{sub s}(w,DELTAT) = P{sub s}(w,0 deg C) + DELTAs(w)DELTAT/nu{sub clay}(w) where DELTAT denotes a temperature difference from 0 deg C, DELTAs(w) is the difference in partial molar entropy between clay water and bulk water, nu{sub clay} (w) is the partial molar volume of the clay water and w denotes the water/solid mass ratio of the clay. As bulk water changes phase at 0 deg C, DELTAs(w) has a different value dependent on whether DELTAT is negative or positive. Above 0 deg C DELTAs(w) is a small value for all relevant densities which means that the pressure response due to temperature changes is small. A further consequence of this fact is that DELTAs(w) is a large positive number below 0 deg C when the external water phase is transformed to ice. Consequently, the model predicts a large drop of swelling pressure with temperature below 0 deg C, in the order of 1.2 MPa/deg C. Specifically, the swelling pressure is zero at a certain (negative) temperature T{sub C}. T{sub C} also quantifies the freezing point of the bentonite sample under consideration, as ice formation in the bentonite does not occur until swelling pressure is lost. A large set of laboratory tests have been performed where fully water saturated samples of bentonites have been exposed to temperatures in the range -10 deg C to +25 deg C. The swelling pressure response has been

  13. Flash-and-freeze: coordinating optogenetic stimulation with rapid freezing to visualize membrane dynamics at synapses with millisecond resolution

    Directory of Open Access Journals (Sweden)

    Shigeki Watanabe

    2016-08-01

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

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

    Science.gov (United States)

    Watanabe, Shigeki

    2016-01-01

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

  15. Immersion freezing of ice nucleation active protein complexes

    Science.gov (United States)

    Hartmann, S.; Augustin, S.; Clauss, T.; Wex, H.; Šantl-Temkiv, T.; Voigtländer, J.; Niedermeier, D.; Stratmann, F.

    2013-06-01

    Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS), the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between -5 °C to -38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA) bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about -6 °C to about -10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei) which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a) the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b) the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice nucleation are attached

  16. Immersion freezing of ice nucleation active protein complexes

    Directory of Open Access Journals (Sweden)

    S. Hartmann

    2013-06-01

    Full Text Available Utilising the Leipzig Aerosol Cloud Interaction Simulator (LACIS, the immersion freezing behaviour of droplet ensembles containing monodisperse particles, generated from a Snomax™ solution/suspension, was investigated. Thereto ice fractions were measured in the temperature range between −5 °C to −38 °C. Snomax™ is an industrial product applied for artificial snow production and contains Pseudomonas syringae} bacteria which have long been used as model organism for atmospheric relevant ice nucleation active (INA bacteria. The ice nucleation activity of such bacteria is controlled by INA protein complexes in their outer membrane. In our experiments, ice fractions increased steeply in the temperature range from about −6 °C to about −10 °C and then levelled off at ice fractions smaller than one. The plateau implies that not all examined droplets contained an INA protein complex. Assuming the INA protein complexes to be Poisson distributed over the investigated droplet populations, we developed the CHESS model (stoCHastic modEl of similar and poiSSon distributed ice nuclei which allows for the calculation of ice fractions as function of temperature and time for a given nucleation rate. Matching calculated and measured ice fractions, we determined and parameterised the nucleation rate of INA protein complexes exhibiting class III ice nucleation behaviour. Utilising the CHESS model, together with the determined nucleation rate, we compared predictions from the model to experimental data from the literature and found good agreement. We found that (a the heterogeneous ice nucleation rate expression quantifying the ice nucleation behaviour of the INA protein complex is capable of describing the ice nucleation behaviour observed in various experiments for both, Snomax™ and P. syringae bacteria, (b the ice nucleation rate, and its temperature dependence, seem to be very similar regardless of whether the INA protein complexes inducing ice

  17. The cytoplasmic Cu,Zn superoxide dismutase of saccharomyces cerevisiae is required for resistance to freeze-thaw stress. Generation of free radicals during freezing and thawing

    DEFF Research Database (Denmark)

    Park, J I; Grant, C M; Davies, Michael Jonathan

    1998-01-01

    The involvement of oxidative stress in freeze-thaw injury to yeast cells was analyzed using mutants defective in a range of antioxidant functions, including Cu,Zn superoxide dismutase (encoded by SOD1), Mn superoxide dismutase (SOD2), catalase A, catalase T, glutathione reductase, gamma......-glutamylcysteine synthetase and Yap1 transcription factor. Only those affecting superoxide dismutases showed decreased freeze-thaw tolerance, with the sod1 mutant and the sod1 sod2 double mutant being most affected. This indicated that superoxide anions were formed during freezing and thawing. This was confirmed since...... the sod1 mutant could be made more resistant by treatment with the superoxide anion scavenger MnCl2, or by freezing in the absence of oxygen, or by the generation of a rho0 petite. Increased expression of SOD2 conferred freeze-thaw tolerance on the sod1 mutant indicating the ability of the mitochondrial...

  18. Effect of conventional and controlled freezing method on the post thaw characteristics of boar spermatozoa.

    Science.gov (United States)

    Baishya, S K; Biswas, R K; Kadirvel, G; Deka, B C; Kumar, Suresh; Sinha, S; Dutta, D J; Saikia, G K

    2014-10-01

    The objective of the present study was to evaluate the effectiveness of conventional, and controlled freezing method adopting three freezing rates 20°C, 40°C and 60°C/min for cryopreservation of boar semen. Sixty sperm-rich fractions of ejaculates from six boars were utilized for freezing of semen with different freezing methods in lactose-egg yolk glycerol extender using 0.5 ml straws. Semen samples were evaluated for sperm motility, live sperm, acrosome integrity, plasma membrane integrity (PMI) by carboxyfluorescein diacetate plus propidium iodide (PI) staining, mitochondrial membrane potential (MMP) by combined JC-1 plus PI staining and lipid peroxidation (LPO) by BODIPY (581/591)-C11 probe after equilibration and after freezing. The results revealed that the post thaw sperm motility, live sperm, live intact acrosome and plasma membrane integrity were significantly (p0.05) mean values of live sperm with high MMP as compared to conventional freezing. However, the post thaw sperm LPO did not influence by difference in freezing methods. No significant difference on the post thaw sperm qualities was recorded among the three controlled freezing rates. All the sperm parameters assessed declined significantly (pboar semen with controlled freezing methods conferred better post thaw sperm quality as compared to conventional method, and the freezing rates of either 20, 40 or 60°C/min could provide better freezability of boar semen.

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

    Directory of Open Access Journals (Sweden)

    Yen-Hsiang Tseng

    2015-05-01

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

  20. Impact of the freeze-drying process on product appearance, residual moisture content, viability, and batch uniformity of freeze-dried bacterial cultures safeguarded at culture collections.

    Science.gov (United States)

    Peiren, Jindrich; Hellemans, Ann; De Vos, Paul

    2016-07-01

    In this study, causes of collapsed bacterial cultures in glass ampoules observed after freeze-drying were investigated as well as the influence of collapse on residual moisture content (RMC) and viability. Also, the effect of heat radiation and post freeze-drying treatments on the RMC was studied. Cake morphologies of 21 bacterial strains obtained after freeze-drying with one standard protocol could be classified visually into four major types: no collapse, porous, partial collapse, and collapse. The more pronounced the collapse, the higher residual moisture content of the freeze-dried product, ranging from 1.53 % for non-collapsed products to 3.62 % for collapsed products. The most important cause of collapse was the mass of the inserted cotton plug in the ampoule. Default cotton plugs with a mass between 21 and 30 mg inside the ampoule did not affect the viability of freeze-dried Aliivibrio fischeri LMG 4414(T) compared to ampoules without cotton plugs. Cotton plugs with a mass higher than 65 mg inside the ampoule induced a full collapsed product with rubbery look (melt-back) and decreasing viability during storage. Heat radiation effects in the freeze-drying chamber and post freeze-drying treatments such as exposure time to air after freeze-drying and manifold drying time prior to heat sealing of ampoules influenced the RMC of freeze-dried products. To produce uniform batches of freeze-dried bacterial strains with intact cake structures and highest viabilities, inserted cotton plugs should not exceed 21 mg per ampoule. Furthermore, heat radiation effects should be calculated in the design of the primary drying phase and manifold drying time before heat sealing should be determined as a function of exposure time to air.

  1. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  2. Diurnal freeze/thaw cycles of the ground surface on the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    YANG MeiXue; YAO TanDong; GOU XiaoHua; HIROSE Nozomu; FUJII Hide Yuki; HAO LiSheng; D.F.LEVIA

    2007-01-01

    The exchange of energy and water between the lithosphere and atmosphere mainly takes place at the ground surface. Therefore, freeze/thaw condition at the ground surface is an important factor in examining the interactions between the land surface and atmosphere. Based on the observation data obtained by CEOP/CAMP-Tibet, the diurnal freeze/thaw cycles of the ground surface near Naqu, central Tibetan Plateau was preliminarily analyzed. The results show that the surface layer was completely frozen for approximately one month. However, the time that the ground surface experienced diurnal freeze/thaw cycles was about 6 months. The high frequency of freeze/thaw cycles at the ground surface significantly influences water and energy exchanges between ground and atmosphere over half a year. The interaction processes between the ground and atmosphere under different soil conditions (such as complete thaw, complete freeze and diurnal freeze/thaw cycles) are issues worthy of further examination.

  3. 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.

  4. 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.

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

    Science.gov (United States)

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

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

  6. Pressure Shift Freezing as Potential Alternative for Generation of Decellularized Scaffolds

    Directory of Open Access Journals (Sweden)

    S. Eichhorn

    2013-01-01

    Full Text Available Background. Protocols using chemical reagents for scaffold decellularization can cause changes in the properties of the matrix, depending on the type of tissue and the chemical reagent. Technologies using physical techniques may be possible alternatives for the production grafts with potential superior matrix characteristics. Material and Methods. We tested four different technologies for scaffold decellularization. Group 1: high hydrostatic pressure (HHP, 1 GPa; Group 2: pressure shift freezing (PSF; Group 3: pulsed electric fields (PEF; Group 4: control group: detergent (SDS. The degree of decellularization was assessed by histological analysis and the measurement of residual DNA. Results. Tissue treated with PSF showed a decellularization with a penetration depth (PD of 1.5 mm and residual DNA content of . HHD treatment caused a PD of 0.2 mm with a residual DNA content of . PD in PEF was 0.5 mm, and the residual DNA content was . In the SDS group, PD was found to be 5 mm, and the DNA content was determined at . Conclusion. PSF showed promising results as a possible technique for scaffold decellularization. The penetration depth of PSF has to be optimized, and the mechanical as well as the biological characteristics of decellularized grafts have to be evaluated.

  7. Crystal Growth and Characterization of CdTe Grown by Vertical Gradient Freeze

    Science.gov (United States)

    Su, Ching-Hua; Lehoczky, S. L.; Raghothamachar, B.; Dudley, M.

    2007-01-01

    In this study, crystals of CdTe were grown from melts by the unseeded vertical gradient freeze method. The quality of grown crystal were studied by various characterization techniques including Synchrotron White Beam X-ray Topography (SWBXT), chemical analysis by glow discharge mass spectroscopy (GDMS), low temperature photoluminescence (PL), and Hall measurements. The SWBXT images from various angles show nearly strain-free grains, grains with inhomogeneous strains, as well as twinning nucleated in the shoulder region of the boule. The GDMS chemical analysis shows the contamination of Ga at a level of 3900 ppb, atomic. The low temperature PL measurement exhibits the characteristic emissions of a Ga-doped sample. The Hall measurements show a resistivity of 1 x l0(exp 7) ohm-cm at room temperature to 3 x 10(exp 9) ohm-cm at 78K with the respective hole and electron concentration of 1.7 x 10(exp 9) cm(exp -3) and 3.9 x 10(exp 7) cm(exp -3) at room temperature.

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

    Science.gov (United States)

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

    2016-07-01

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

  9. On the transition between heterogeneous and homogeneous freezing

    Directory of Open Access Journals (Sweden)

    K. Gierens

    2003-01-01

    Full Text Available Box model simulations of an uplifting and adiabatically cooling cloud of aerosol have been performed in order to study the transition between cirrus formation dominated by homogeneous nucleation of ice to that dominated by heterogeneous nucleation. The aerosol was assumed to consist of an internal mixture of sulfuric acid solution droplets with inclusions of soot. The parametrisation of De Mott et al. (1997 was used to simulate the heterogeneous nucleation of ice in such droplets with soot inclusions. The simulations show that the transition from heterogeneous to homogeneous nucleation occurs over a narrow range of soot concentration. Thus it seems to be possible to fix critical concentrations of heterogeneous ice nuclei which must be exceeded if heterogeneous freezing dominates cirrus formation. A formula has been derived that allows to compute the critical concentrations of heterogeneous ice nuclei as a function of temperature, updraft speed, ambient pressure, and supersaturation at which heterogeneous freezing occurs. Generally, homogeneous nucleation dominates in regions with updrafts stronger than 20 cm s -1, with the exception of heavily polluted areas which could be common in the northern hemisphere due to air traffic, where updrafts of the order 1 m s-1 may be necessary to render heterogeneous nucleation unimportant. According to the present results it cannot be excluded that heterogeneous nucleation plays a more important role for cirrus formation in the northern midlatitudes than anywhere else. A possible consequence of these results is that air pollution may lead to a higher coverage of cirrus clouds, but then these clouds will be optically thinner than clouds formed by homogeneous freezing, with the exception of regions where condensation trails are frequent.

  10. 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

  11. Static critical fluctuations on the freeze-out surface

    CERN Document Server

    Jiang, Lijia; Song, Huichao

    2016-01-01

    In this proceeding, we summarize the main results of our recent paper, which introduces a freeze-out scheme to the dynamical models near the QCD critical point. Within such framework of static critical fluctuations, the Beam Energy Scan (BES) data of $C_4$ and $\\kappa \\sigma^2$ for net protons within different $p_T$ ranges can be roughly described. Besides, the momentum acceptance dependence of higher cumulants at lower collision energies can also be qualitatively described. However, $C_2$ and $C_3$ are always over-predicted due to the positive static critical fluctuations.

  12. Numerical Simulation on Freezing Process of Saturated Granlar Soil

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The relation between ice pressure and load as a criterion of segregated ice initiation is introduced into the rigid ice model to simulate frost heave in saturated and granular soil. The calculated results show that unfrozen water content, thermal conductivity and hydraulic conductivity change greatly in frozen fringe. In numerical simulations, the influence of load, hydraulic conductivity and property of soil containing water on the process of soil freezing are analyzed, and the simulation curves such as cumulative heave,the change of depth of frozen and the distributions of water content are similar to the observations reported elsewhere.

  13. 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.

  14. Physical Stability of Freeze-Dried Isomalt Diastereomer Mixtures

    DEFF Research Database (Denmark)

    Koskinen, Anna-Kaisa; Fraser-Miller, Sara J.; Bøtker, Johan P.

    2016-01-01

    of the diastereomer compositions showed signs of physical instability when stored in the highest relative humidity condition. The four different crystalline diastereomer mixtures showed specific identifiable solid state properties. Conclusions Isomalt was shown to be a suitable excipient for freeze-drying. Preferably...... a mixture of the diastereomers should be used, as the mixture containing only one of the isomers showed physical instability. A mixture containing a 1:1 ratio of the two diastereomers showed the best physical stability in the amorphous form....

  15. Calorimetric analysis of cryopreservation and freeze-drying formulations.

    Science.gov (United States)

    Sun, Wendell Q

    2015-01-01

    Differential scanning calorimetry (DSC) is a commonly used thermal analysis technique in cryopreservation and freeze-drying research. It has been used to investigate crystallization, eutectic formation, glass transition, devitrification, recrystallization, melting, polymorphism, molecular relaxation, phase separation, water transport, thermochemistry, and kinetics of complex reactions (e.g., protein denaturation). Such information can be used for the optimization of protective formulations and process protocols. This chapter gives an introduction to beginners who are less familiar with this technique. It covers the instrument and its basic principles, followed by a discussion of the methods as well as examples of specific applications.

  16. STUDY ON THE DAMAGE MECHANISM OF PORE STRUCTURE IN CONCRETE SUBJECTED TO FREEZE-THAW CYCLES

    OpenAIRE

    Ben Li; Kaiyuan Wang; Jize Mao; Qingyong Guo

    2015-01-01

    It is well know that freeze-thaw cycles play the most significant role in the durability evolution in concrete structures, freeze-thaw cycles have been accounted as one of the major factors on the damage and demolition of concrete. Microscopic parameters have been used for describing the characterizations of damage in concrete under freeze-thaw actions by researchers. However, their models could not provide specific damage factors or parameters. In this paper, a new damage model and equation ...

  17. Classical nucleation theory of immersion freezing: sensitivity of contact angle schemes to thermodynamic and kinetic parameters

    Science.gov (United States)

    Ickes, Luisa; Welti, André; Lohmann, Ulrike

    2017-02-01

    Heterogeneous ice formation by immersion freezing in mixed-phase clouds can be parameterized in general circulation models (GCMs) by classical nucleation theory (CNT). CNT parameterization schemes describe immersion freezing as a stochastic process, including the properties of insoluble aerosol particles in the droplets. There are different ways to parameterize the properties of aerosol particles (i.e., contact angle schemes), which are compiled and tested in this paper. The goal of this study is to find a parameterization scheme for GCMs to describe immersion freezing with the ability to shift and adjust the slope of the freezing curve compared to homogeneous freezing to match experimental data. We showed in a previous publication that the resulting freezing curves from CNT are very sensitive to unconstrained kinetic and thermodynamic parameters in the case of homogeneous freezing. Here we investigate how sensitive the outcome of a parameter estimation for contact angle schemes from experimental data is to unconstrained kinetic and thermodynamic parameters. We demonstrate that the parameters describing the contact angle schemes can mask the uncertainty in thermodynamic and kinetic parameters. Different CNT formulations are fitted to an extensive immersion freezing dataset consisting of size-selected measurements as a function of temperature and time for different mineral dust types, namely kaolinite, illite, montmorillonite, microcline (K-feldspar), and Arizona test dust. We investigated how accurate different CNT formulations (with estimated fit parameters for different contact angle schemes) reproduce the measured freezing data, especially the time and particle size dependence of the freezing process. The results are compared to a simplified deterministic freezing scheme. In this context, we evaluated which CNT-based parameterization scheme able to represent particle properties is the best choice to describe immersion freezing in a GCM.

  18. Effect of cooling rate on the microstructure and porosity of alumina produced by freeze casting

    OpenAIRE

    Nieto Isabel María; Rodríguez-Parra Jesús M.; Moreno Rodrigo

    2012-01-01

    Freeze casting is a well-known shaping technique to produce materials with directional porosity. One of the major problems is the difficulty to control the cooling rate thus leading to gradients in pore size and homogeneity. This work deals with the manufacture of alumina ceramics with directional porosity by freeze casting of aqueous suspensions. An experimental set-up was prepared in order to apply different cooling rates. Freeze casting tests were done with an aqueous alumina suspens...

  19. Effect of freeze-drying, cryoprotectants and storage conditions on the stability of secondary structure of insulin-loaded solid lipid nanoparticles.

    Science.gov (United States)

    Soares, Sandra; Fonte, Pedro; Costa, Ana; Andrade, José; Seabra, Vítor; Ferreira, Domingos; Reis, Salette; Sarmento, Bruno

    2013-11-18

    This study aims to monitor the secondary structure behaviour of insulin when it is encapsulated into solid lipid nanoparticles (SLN), under the influence of several critical processing parameters. Insulin was used as a therapeutic protein model. Physicochemical properties of insulin-loaded SLN (Ins-SLN) were assessed, with special focus on the insulin secondary structure after its encapsulation into SLN and after freeze-drying using different cryoprotectants (glucose, fructose and sorbitol). Additionally, a 6-month stability study was performed to evaluate the maintenance of insulin secondary structure over time at different storage conditions (4 °C/60% RH, 25 °C/60% RH, 40 °C/75% RH). Ins-SLN were successfully produced with a mean and narrow particle size around 400 nm, zeta potential around -13 mV, an insulin association efficiency of 84%. Physical-chemical properties of SLN were maintained after freeze-drying. FTIR results showed that encapsulated insulin maintained a native-like structure in a degree of similarity around 92% after production, and 84% after freeze-drying. After 6 months, freeze-dried Ins-SLN without cryoprotectant stored at 40 °C/75% RH presented the same degree of structure preservation and morphology. Results revealed that insulin structure can be significantly protected by SLN matrix itself, without a cryoprotectant agent, even using a non-optimized freeze-drying process, and under the harsher storage conditions. Multivariable experimental settled the process parameters to fit with the desired product quality attributes regarding protein and nanoparticle stability.

  20. Advances in studies on concrete durability and countermeasures against freezing-thawing effects

    Institute of Scientific and Technical Information of China (English)

    WuJian Yan; FuJun Niu; XianJun Zhang; Jing Luo; GuoAn Yin

    2014-01-01

    This-paper-is-a-meta-analysis-of-recent-domestic-and-foreign-research-on-freezing-thawing-effects-on-concrete-durability.-The-main-theories-on-the-mechanisms-of-freeze-thaw-damage-to-concrete-are-introduced:-the-hydrostatic-pressure-theory,-the-osmotic-pressure-theory,-the-critical-water-saturation-degree-theory,-the-dual-mechanism-theory,-and-the-mi-cro-ice-crystal-lens-model-theory.-The-influence-laws-of-freezing-thawing-on-the-mechanical-properties-of-concrete-are-summarized,-and-countermeasures-to-improve-concrete-durability-in-freezing-thawing-circumstances-are-presented.-This-work-provides-valuable-references-for-future-engineering-constructions-in-cold-regions.