Fast high-pressure freezing of protein crystals in their mother liquor

International Nuclear Information System (INIS)

Burkhardt, Anja; Warmer, Martin; Panneerselvam, Saravanan; Wagner, Armin; Zouni, Athina; Glöckner, Carina; Reimer, Rudolph; Hohenberg, Heinrich; Meents, Alke

2012-01-01

Protein crystals were vitrified using high-pressure freezing in their mother liquor at 210 MPa and 77 K without cryoprotectants or oil coating. The method was successfully applied to photosystem II, which is representative of a membrane protein with a large unit cell and weak crystal contacts. High-pressure freezing (HPF) is a method which allows sample vitrification without cryoprotectants. In the present work, protein crystals were cooled to cryogenic temperatures at a pressure of 210 MPa. In contrast to other HPF methods published to date in the field of cryocrystallography, this protocol involves rapid sample cooling using a standard HPF device. The fast cooling rates allow HPF of protein crystals directly in their mother liquor without the need for cryoprotectants or external reagents. HPF was first attempted with hen egg-white lysozyme and cubic insulin crystals, yielding good to excellent diffraction quality. Non-cryoprotected crystals of the membrane protein photosystem II have been successfully cryocooled for the first time. This indicates that the presented HPF method is well suited to the vitrification of challenging systems with large unit cells and weak crystal contacts

Eutectics as improved pharmaceutical materials: design, properties and characterization.

Science.gov (United States)

Cherukuvada, Suryanarayan; Nangia, Ashwini

2014-01-28

Eutectics are a long known class of multi-component solids with important and useful applications in daily life. In comparison to other multi-component crystalline solids, such as salts, solid solutions, molecular complexes and cocrystals, eutectics are less studied in terms of molecular structure organization and bonding interactions. Classically, a eutectic is defined based on its low melting point compared to the individual components. In this article, we attempt to define eutectics not just based on thermal methods but from a structural organization view point, and discuss their microstructures and properties as organic materials vis-a-vis solid solutions and cocrystals. The X-ray crystal structure of a cocrystal is different from that of the individual components whereas the unit cell of a solid solution is similar to that of one of the components. Eutectics are closer to the latter species in that their crystalline arrangement is similar to the parent components but they are different with respect to the structural integrity. A solid solution possesses structural homogeneity throughout the structure (single phase) but a eutectic is a heterogeneous ensemble of individual components whose crystal structures are like discontinuous solid solutions (phase separated). Thus, a eutectic may be better defined as a conglomerate of solid solutions. A structural analysis of cocrystals, solid solutions and eutectics has led to an understanding that materials with strong adhesive (hetero) interactions between the unlike components will lead to cocrystals whereas those having stronger cohesive (homo/self) interactions will more often give rise to solid solutions (for similar structures of components) and eutectics (for different structures of components). We demonstrate that the same crystal engineering principles which have been profitably utilized for cocrystal design in the past decade can now be applied to make eutectics as novel composite materials, illustrated by

Organic alloy systems suitable for the investigation of regular binary and ternary eutectic growth

Science.gov (United States)

Sturz, L.; Witusiewicz, V. T.; Hecht, U.; Rex, S.

2004-09-01

Transparent organic alloys showing a plastic crystal phase were investigated experimentally using differential scanning calorimetry and directional solidification with respect to find a suitable model system for regular ternary eutectic growth. The temperature, enthalpy and entropy of phase transitions have been determined for a number of pure substances. A distinction of substances with and without plastic crystal phases was made from their entropy of melting. Binary phase diagrams were determined for selected plastic crystal alloys with the aim to identify eutectic reactions. Examples for lamellar and rod-like eutectic solidification microstructures in binary systems are given. The system (D)Camphor-Neopentylglycol-Succinonitrile is identified as a system that exhibits, among others, univariant and a nonvariant eutectic reaction. The ternary eutectic alloy close to the nonvariant eutectic composition solidifies with a partially faceted solid-liquid interface. However, by adding a small amount of Amino-Methyl-Propanediol (AMPD), the temperature of the nonvariant eutectic reaction and of the solid state transformation from plastic to crystalline state are shifted such, that regular eutectic growth with three distinct nonfaceted phases is observed in univariant eutectic reaction for the first time. The ternary phase diagram and examples for eutectic microstructures in the ternary and the quaternary eutectic alloy are given.

Growth of LiF/LiBaF.sub.3./sub. eutectic scintillator crystals and their optical properties

Czech Academy of Sciences Publication Activity Database

Kurosawa, S.; Yamaji, A.; Pejchal, Jan; Yokota, Y.; Ohashi, Y.; Kamada, K.; Yoshikawa, A.

2017-01-01

Roč. 52, č. 10 (2017), s. 5531-5536 ISSN 0022-2461 Grant - others:AV ČR(CZ) JSPS-17-18 Program:Bilaterální spolupráce Institutional support: RVO:68378271 Keywords : scintillators * eutectics * crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 2.599, year: 2016

Surface freezing of water.

Science.gov (United States)

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

2016-01-01

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

Ultrafast crystallization and thermal stability of In-Ge doped eutectic Sb70Te30 phase change material

International Nuclear Information System (INIS)

Lee Meiling; Miao Xiangshui; Ting Leehou; Shi Luping

2008-01-01

Effect of In and Ge doping in the form of In 2 Ge 8 Sb 85 Te 5 on optical and thermal properties of eutectic Sb 70 Te 30 alloys was investigated. Crystalline structure of In 2 Ge 8 Sb 85 Te 5 phase change material consists of a mixture of phases. Thermal analysis shows higher crystallization temperature and activation energy for crystallization. Isothermal reflectivity-time measurement shows a growth-dominated crystallization mechanism. Ultrafast crystallization speed of 30 ns is realized upon irradiation by blue laser beam. The use of ultrafast and thermally stable In 2 Ge 8 Sb 85 Te 5 phase change material as mask layer in aperture-type super-resolution near-field phase change disk is realized to increase the carrier-to-noise ratio and thermal stability

The Application of ATD and DSC Methods to Study of the EN AC-48000 Alloy Phase Transformations

Directory of Open Access Journals (Sweden)

Piątkowski J.

2017-06-01

Full Text Available Tests concerning EN AC 48000 (AlSi12CuNiMg alloy phase transition covered (ATD thermal analysis and (DSC differential scanning calorimetry specifying characteristic temperatures and enthalpy of transformations. ATD thermal analysis shows that during cooling there exist: pre-eutectic crystallization effect of Al9Fe2Si phase, double eutectic and crystallization α(Al+β(Si and multi-component eutectic crystallization. During heating, DSC curve showed endothermic effect connected with melting of the eutectic α(Al+β(Si and phases: Al2Cu, Al3Ni, Mg2Si and Al9Fe2Si being its components. The enthalpy of this transformation constitutes approx. +392 J g-1. During freezing of the alloy, DSC curve showed two exothermal reactions. One is most likely connected with crystallization of Al9Fe2Si phase and the second one comes from freezing of the eutectic α(Al+β(Si. The enthalpy of this transformation constitutes approx. -340 J g-1. Calorimetric test was accompanied by structural test (SEM conducted with the use of optical microscope Reichert and scanning microscope Hitachi S-4200. There occurred solution’s dendrites α(Al, eutectic silicon crystal (β and two types of eutectic solution: double eutectic α(Al+β(Si and multi-component eutectic α+AlSiCuNiMg+β.

Separation of glucose and fructose by freezing crystallization

Energy Technology Data Exchange (ETDEWEB)

Silva, A.T.C.R.; Martinez, K.C.L. [Federal University of Sao Carlos, Chemical Engineering Department, Industrial Crystallization Laboratory - Rod. Washington Luis km 235, P.O. Box 676, CEP:13565-905, Sao Carlos-SP (Brazil); Brito, A.B.N. [Federal University of Espirito Santo, Engineering and Computing Dept. - Rodovia BR 101 Norte, Km. 60, Bairro Litoraneo, CEP 29932-540, Sao Mateus-ES (Brazil); Giulietti, M. [Laboratory of Chemical Process and Particle Technology of Institute for Technological Research, Av. Prof. Almeida Prado 532 -Universitary City, CEP:05508-901, Sao Paulo-SP (Brazil)

2010-10-15

This work comprises the implementation of a methodology for the study of an industrial crystallization process by freezing and cooling to be applied in the separation of sugars with industrial relevance (glucose and fructose). The main interest is the production of fructose. This sugar is obtained by sucrose hydrolysis in acidic solutions, which yields an equimolar mixture of glucose and fructose. The developed separation process is based on the solubility difference between the sugars. Experiments were carried out in a jacketed glass crystallizer where the solution coming from the sucrose acid inversion was submitted to a slow cooling. Since glucose has lower solubility than fructose, it crystallizes in the bulk as the temperature is lowered, thus it can be removed from the solution by filtration or centrifugation. Best fructose-glucose separation was achieved for a total sugar concentration of 50 wt%. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Evidence of eutectic crystallization and transient nucleation in Al89La6Ni5 amorphous alloy

International Nuclear Information System (INIS)

Zhuang, Y. X.; Jiang, J. Z.; Lin, Z. G.; Mezouar, M.; Crichton, W.; Inoue, A.

2001-01-01

The phase evolution with the temperature and time in the process of crystallization of Al 89 La 6 Ni 5 amorphous alloy has been investigated by in situ high-temperature and high-pressure x-ray powder diffraction using synchrotron radiation. Two crystalline phases, fcc-Al and a metastable bcc-(AlNi) 11 La 3 -like phase, were identified after the first crystallization reaction, revealing a eutectic reaction instead of a primary reaction suggested in the literature. Time-dependent nucleation in the amorphous alloy is detected and the experimental data can be fitted by both the Zeldovich's and Kashchiev's transient nucleation models with transient nucleation times of 220 and 120 min, respectively. Copyright 2001 American Institute of Physics

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

International Nuclear Information System (INIS)

Parga, Clemente J.; Journeau, Christophe; Parga, Clemente J.; Tokuhiro, Akira

2012-01-01

With the aim of reducing the high temperature measurement uncertainty of nuclear reactor severe accident experimental tests at the PLINIUS platform in Cadarache Research Centre, France, a variety of graphite cells containing a metal-carbon eutectic mix have been tested to assess the melting/freezing temperature reproducibility and their feasibility as calibration cells for thermometers. The eutectic cells have been thermally cycled in an induction furnace to assess the effect of heating/cooling rate, metal purity, graphite crucible design, and binary system constituents on the eutectic transformation temperature. A bi-chromatic pyrometer was used to perform temperature measurements in the graphite cell black cavity containing the metal-carbon eutectic mix. The eutectic points analyzed are all over 1100 C and cover an almost thousand degree span, i.e. from the Fe-Fe 3 C to the Ru-C eutectic. The induction heating permitted the attainment of heating and cooling rates of over 200 C/min under an inert atmosphere. The conducted tests allowed the determination of general trends and peculiarities of the solid. liquid transformation temperature under non-equilibrium and non-steady-state conditions of a variety of eutectic alloys (Fe-C, Co-C, Ti-C and Ru-C binary systems). (authors)

Transformation of eutectic emulsion to nanosuspension fabricating with solvent evaporation and ultrasonication technique

Science.gov (United States)

Phaechamud, Thawatchai; Tuntarawongsa, Sarun

2016-01-01

Eutectic solvent can solubilize high amount of some therapeutic compounds. Volatile eutectic solvent is interesting to be used as solvent in the preparation of nanosuspension with emulsion solvent evaporation technique. The mechanism of transformation from the eutectic emulsion to nanosuspension was investigated in this study. The 30% w/w ibuprofen eutectic solution was used as the internal phase, and the external phase is composed of Tween 80 as emulsifier. Ibuprofen nanosuspension was prepared by eutectic emulsion solvent evaporating method followed with ultrasonication. During evaporation process, the ibuprofen concentration in emulsion droplets was increased leading to a drug supersaturation but did not immediately recrystallize because of low glass transition temperature (Tg) of ibuprofen. The contact angle of the internal phase on ibuprofen was apparently lower than that of the external phase at all times of evaporation, indicating that the ibuprofen crystals were preferentially wetted by the internal phase than the external phase. From calculated dewetting value ibuprofen crystallization occurred in the droplet. Crystallization of the drug was initiated with external mechanical force, and the particle size of the drug was larger due to Ostwald ripening. Cavitation force from ultrasonication minimized the ibuprofen crystals to the nanoscale. Particle size and zeta potential of formulated ibuprofen nanosuspension were 330.87±51.49 nm and −31.1±1.6 mV, respectively, and exhibited a fast dissolution. Therefore, the combination of eutectic emulsion solvent evaporation method with ultrasonication was favorable for fabricating an ibuprofen nanosuspension, and the transformation mechanism was attained successfully. PMID:27366064

Transformation of eutectic emulsion to nanosuspension fabricating with solvent evaporation and ultrasonication technique

Directory of Open Access Journals (Sweden)

Phaechamud T

2016-06-01

Full Text Available Thawatchai Phaechamud,1 Sarun Tuntarawongsa2 1Department of Pharmaceutical Technology, 2Pharmaceutical Intelligence Unit Prachote Plengwittaya, Faculty of Pharmacy, Silpakorn University, Nakhon Pathom, Thailand Abstract: Eutectic solvent can solubilize high amount of some therapeutic compounds. Volatile eutectic solvent is interesting to be used as solvent in the preparation of nanosuspension with emulsion solvent evaporation technique. The mechanism of transformation from the eutectic emulsion to nanosuspension was investigated in this study. The 30% w/w ibuprofen eutectic solution was used as the internal phase, and the external phase is composed of Tween 80 as emulsifier. Ibuprofen nanosuspension was prepared by eutectic emulsion solvent evaporating method followed with ultrasonication. During evaporation process, the ibuprofen concentration in emulsion droplets was increased leading to a drug supersaturation but did not immediately recrystallize because of low glass transition temperature (Tg of ibuprofen. The contact angle of the internal phase on ibuprofen was apparently lower than that of the external phase at all times of evaporation, indicating that the ibuprofen crystals were preferentially wetted by the internal phase than the external phase. From calculated dewetting value ibuprofen crystallization occurred in the droplet. Crystallization of the drug was initiated with external mechanical force, and the particle size of the drug was larger due to Ostwald ripening. Cavitation force from ultrasonication minimized the ibuprofen crystals to the nanoscale. Particle size and zeta potential of formulated ibuprofen nanosuspension were 330.87±51.49 nm and -31.1±1.6 mV, respectively, and exhibited a fast dissolution. Therefore, the combination of eutectic emulsion solvent evaporation method with ultrasonication was favorable for fabricating an ibuprofen nanosuspension, and the transformation mechanism was attained successfully. Keywords

Modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium

Energy Technology Data Exchange (ETDEWEB)

Patakham, Ussadawut [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand); Kajornchaiyakul, Julathep [National Metal and Material Technology Center, National Science and Technology Development Agency, 114 Thailand Science Park, Klong Nueng, Klong Luang, Pathumthani 12120 (Thailand); Limmaneevichitr, Chaowalit, E-mail: chaowalit.lim@kmutt.ac.th [Manufacturing and Systems Engineering Program, Department of Production Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, 126 Pracha-Utid Rd., Bangmod, Tungkhru, Bangkok 10140 (Thailand)

2013-10-25

Highlights: •Morphologies and growth of Sc and Sr-modified eutectic silicon resemble those of dendrites. •Crystal orientation of eutectic aluminum depends on growth characteristics of eutectic silicon. •We report strong evidence of the occurrence of an impurity-induced twinning mechanism. -- Abstract: The modification mechanism of eutectic silicon in Al–6Si–0.3Mg alloy with scandium was studied. The crystallographic orientation relationships between primary dendrites and the eutectic phase of unmodified and modified Al–6Si–0.3 Mg alloys were determined using electron backscatter diffraction (EBSD). The orientation of aluminum modified with scandium in the eutectic phase was different from that of the neighboring primary dendrites. This result implies that eutectic aluminum grows epitaxially from the surrounding primary aluminum dendrites in the unmodified alloy and that eutectic aluminum grows competitively from the surrounding primary aluminum dendrites in the modified alloy. The pole figure maps of eutectic Si in the [1 0 0], [1 1 0] and [1 1 1] axes of the unmodified and Sc-modified alloys were different, suggesting that the eutectic Al and Si crystals in modified alloy growth are more isotropic and cover a larger set of directions. The lattice fringes of Si of the alloys with and without Sc modification were different in the TEM results. The lattice fringes of Si in modified alloy were found to be multiple twins. However, this was not observed in the unmodified alloy. The growth characteristic of eutectic Si crystal in modified alloy suggests the occurrence of multiple twinning reactions and the formation of a high density of twins. This modification mechanism by Sc is explained by the results of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analysis, which provide strong evidence of the occurrence of the impurity-induced twinning (IIT) mechanism.

Surface freezing of water

OpenAIRE

P?rez-D?az, J. L.; ?lvarez-Valenzuela, M. A.; Rodr?guez-Celis, F.

2016-01-01

Freezing, melting, evaporation and condensation of water are essential ingredients for climate and eventually life on Earth. In the present work, we show how surface freezing of supercooled water in an open container is conditioned and triggered?exclusively?by humidity in air. Additionally, a change of phase is demonstrated to be triggered on the water surface forming surface ice crystals prior to freezing of bulk. The symmetry of the surface crystal, as well as the freezing point, depend on ...

Novel Applications of Eutectic Freeze Crystallization

NARCIS (Netherlands)

Lu, X.

2014-01-01

During the last decades, the consumption of raw materials and energy in the world has faced a tremendous increase with a corresponding industrial waste volume increases, which treatment poses serious challenges. From an economical point of view, the waste has values as it contains valuable matters.

Silumins alloy crystallization

Directory of Open Access Journals (Sweden)

S. Pietrowski

2009-07-01

Full Text Available This paper presents the results of research, by ATD method, of hypo-, near- and hyperutectic silumins crystallization containing the following alloying additives: Mg, Ni, Cu, Cr, Mo, W, V. It has been shown that, depending on their concentration may crystallize pre-eutectic or eutectic multicomponent phases containing these alloy additives. It has been revealed that any subsequent crystallizable phase nucleate and grows near the liquid/former crystallized phase interface. In multiphases compound also falls the silicon, resulting in a reduction in its quantity and the fragmentation in the eutectic mixture. As a result, it gets a high hardness of silumins in terms of 110-220HB.

Directionally solidified Al2O3/GAP eutectic ceramics by micro-pulling-down method

Science.gov (United States)

Cao, Xue; Su, Haijun; Guo, Fengwei; Tan, Xi; Cao, Lamei

2016-11-01

We reported a novel route to prepare directionally solidified (DS) Al2O3/GAP eutectic ceramics by micro-pulling-down (μ-PD) method. The eutectic crystallizations, microstructure characters and evolutions, and their mechanical properties were investigated in detail. The results showed that the Al2O3/GAP eutectic composites can be successfully fabricated through μ-PD method, possessed smooth surface, full density and large crystal size (the maximal size: φ90 mm × 20 mm). At the process of Diameter, the as-solidified Al2O3/GAP eutectic presented a combination of "Chinese script" and elongated colony microstructure with complex regular structure. Inside the colonies, the rod-type or lamellar-type eutectic microstructures with ultra-fine GAP surrounded by the Al2O3 matrix were observed. At an appropriate solidificational rate, the binary eutectic exhibited a typical DS irregular eutectic structure of "chinese script" consisting of interpenetrating network of α-Al2O3 and GAP phases without any other phases. Therefore, the interphase spacing was refined to 1-2 µm and the irregular microstructure led to an outstanding vickers hardness of 17.04 GPa and fracture toughness of 6.3 MPa × m1/2 at room temperature.

Influence of convection on eutectic microstructure

Science.gov (United States)

Baskaran, V.; Eisa, G. F.; Wilcox, W. R.

1985-01-01

When the MnBi-Bi eutectic is directionally solidified, it forms fibers of MnBi in a matrix of bismuth. When the material solidified in space at rates of 30 and 50 cm/hr, the average fiber spacing lambda was about one half of the value obtained in cases in which the same material solidified on earth. Neither an altered temperature gradient nor a fluctuating freezing rate are apparently responsible for the change in lambda, and the possibility is studied that natural convection increases lambda on earth by perturbing the compositional field in the melt ahead of the growing solid. A theoretical analysis is conducted along with some experiments. On the basis of the theoretical results for lamellar growth, it is concluded that the spacing lambda increases with increasing stirring, especially at small freezing rates. The experiments indicate that at low growth rates the cross-sectional area of the MnBi blades increases with increased stirring and with decreased growth rate.

Controlled Crystallization of the Lipophilic Drug Fenofibrate During Freeze-Drying : Elucidation of the Mechanism by In-Line Raman Spectroscopy

NARCIS (Netherlands)

de Waard, Hans; De Beer, Thomas; Hinrichs, Wouter L J; Vervaet, Chris; Remon, Jean-Paul; Frijlink, Henderik W

2010-01-01

We developed a novel process, "controlled crystallization during freeze-drying" to produce drug nanocrystals of poorly water-soluble drugs. This process involves freeze-drying at a relatively high temperature of a drug and a matrix material from a mixture of tertiary butyl alcohol and water,

Evaporation Behavior and Characterization of Eutectic Solvent and Ibuprofen Eutectic Solution.

Science.gov (United States)

Phaechamud, Thawatchai; Tuntarawongsa, Sarun; Charoensuksai, Purin

2016-10-01

Liquid eutectic system of menthol and camphor has been reported as solvent and co-solvent for some drug delivery systems. However, surprisingly, the phase diagram of menthol-camphor eutectic has not been reported previously. The evaporation behavior, physicochemical, and thermal properties of this liquid eutectic and ibuprofen eutectic solution were characterized in this study. Differential scanning calorimetry (DSC) analysis indicated that a eutectic point of this system was near to 1:1 menthol/camphor and its eutectic temperature was -1°C. The solubility of ibuprofen in this eutectic was 282.11 ± 6.67 mg mL(-1) and increased the drug aqueous solubility fourfold. The shift of wave number from Fourier transform infrared spectroscopy (FTIR) indicated the hydrogen bonding of each compound in eutectic mixture. The weight loss from thermogravimetric analysis of menthol and camphor related to the evaporation and sublimation, respectively. Menthol demonstrated a lower apparent sublimation rate than camphor, and the evaporation rate of eutectic solvent was lower than the sublimation rate of camphor but higher than the evaporation of menthol. The evaporation rate of the ibuprofen eutectic solution was lower than that of the eutectic solvent because ibuprofen did not sublimate. This eutectic solvent prolonged the ibuprofen release with diffusion control. Thus, the beneficial information for thermal behavior and related properties of eutectic solvent comprising menthol-camphor and ibuprofen eutectic solution was attained successfully. The rather low evaporation of eutectic mixture will be beneficial for investigation and tracking the mechanism of transformation from nanoemulsion into nanosuspension in the further study using eutectic as oil phase.

Local structural environments of Ge doped in eutectic Sb-Te film before and after crystallization

Science.gov (United States)

Shin, Sang Yeol; Cheong, Byung-ki; Choi, Yong Gyu

2018-06-01

Electrical phase change device using the Ge-doped eutectic Sb-Te (e.g., Ge1Sb8Te2) film is known to exhibit improved energy efficiency thanks to lowered threshold voltage as well as decreased power consumption for the reset operation, as compared with Ge2Sb2Te5 film. Ge K-edge EXAFS analysis is employed in this study in an effort to elucidate such merits of Ge1Sb8Te2 film in connection with its local atomic arrangements. It is then verified that a Ge atom is four-fold coordinated in its nearest-neighboring shell both in the as-deposited and in the annealed films. It needs to be highlighted that approximately two Sb atoms constitute the Ge tetrahedral units in its amorphous state; however, after being crystallized, heteropolar Ge-Sb bonds hardly exist in this Ge1Sb8Te2 film. It has been known that crystallization temperature and activation energy for crystallization of this Ge1Sb8Te2 composition are greater than those of Ge2Sb2Te5 composition. In addition, these two phase change materials exhibit distinctly different crystallization mechanisms, i.e., nucleation-dominant for Ge2Sb2Te5 film but growth-dominant for Ge1Sb8Te2 film. These discrepancies in the crystallization-related properties are delineated in terms of the local structural changes verified from the present EXAFS analysis.

Eutectic mixtures of some fatty acids for latent heat storage: Thermal properties and thermal reliability with respect to thermal cycling

International Nuclear Information System (INIS)

Sari, Ahmet

2006-01-01

Accelerated thermal cycle tests have been conducted to study the change in melting temperatures and latent heats of fusion of the eutectic mixtures of lauric acid (LA)-myristic acid (MA), lauric acid (LA)-palmitic acid (PA) and myristic acid (MA)-stearic acid (SA) as latent heat storage materials. The thermal properties of these materials were determined by the differential scanning calorimetry (DSC) analysis method. The thermal reliability of the eutectic mixtures after melt/freeze cycles of 720, 1080 and 1460 was also evaluated using the DSC curves. The accelerated thermal cycle tests indicate that the melting temperatures usually tend to decrease, and the variations in the latent heats of fusion are irregular with increasing number of thermal cycles. Moreover, the probable reasons for the change in thermal properties of the eutectic mixtures after repeated thermal cycles were investigated. Fourier Transform Infrared (FT-IR) spectroscopic analysis indicates that the accelerated melt/freeze processes do not cause any degradation in the chemical structure of the mixtures. The change in thermal properties of the eutectic mixtures with increasing number of thermal cycles is only because of the presence of certain amounts of impurities in the fatty acids used in their preparation. It is concluded that the tested eutectic mixtures have reasonable thermal properties and thermal reliability as phase change materials (PCMs) for latent heat storage in any solar heating applications that include a four year utilization period

Stable, low-cost phase change material for building applications: The eutectic mixture of decanoic acid and tetradecanoic acid

International Nuclear Information System (INIS)

Kahwaji, Samer; Johnson, Michel B.; Kheirabadi, Ali C.; Groulx, Dominic; White, Mary Anne

2016-01-01

Highlights: • Decanoic/tetradecanoic acid eutectic at 0.82 ± 0.02 mole fraction (78 ± 2 mass%) decanoic acid. • Melting of eutectic at 20.5 ± 1.5 °C, useful for building applications. • High enthalpy change, 153 ± 15 J g"−"1, is promising. • Negligible change in stability after 3000 melt–freeze cycles. - Abstract: We present a thorough characterization of the thermal properties and thermal reliability of the eutectic mixture of decanoic acid with tetradecanoic acid, as a phase change material (PCM) of potential interest for passive temperature control in buildings. From the temperature-composition binary phase diagram we found that the eutectic composition is 0.82 ± 0.02 mole fraction (78 ± 2 mass%) decanoic acid. We thoroughly characterized the thermal properties of the eutectic mixture. The eutectic composition has a high latent heat of fusion Δ_f_u_sH = 153 ± 15 J g"−"1 and a melting temperature T_o_n_s_e_t = 20.5 ± 1.5 °C. The heat capacity measured as a function of temperature for the solid and liquid phases just below and above the melting point is 1.9 and 2.1 ± 0.2 J K"−"1 g"−"1, respectively. The average value of the thermal conductivity of the solid phase measured between −33 and 9 °C is κ_s = 0.20 ± 0.02 W m"−"1 K"−"1 and for the liquid phase, the thermal conductivity is κ_l = 0.23 ± 0.03 W m"−"1 K"−"1 for 28 and 38 °C. The mixture has a good long-term thermal stability as indicated by negligible changes in Δ_f_u_sH and T_o_n_s_e_t after 3000 melt–freeze cycles. The parameters determined in this work allow more accurate modeling and optimization of the behavior of the eutectic mixture in preparation for implementation as a thermal energy storage PCM.

Using Power Ultrasound to Accelerate Food Freezing Processes: Effects on Freezing Efficiency and Food Microstructure.

Science.gov (United States)

Zhang, Peizhi; Zhu, Zhiwei; Sun, Da-Wen

2018-05-31

Freezing is an effective way of food preservation. However, traditional freezing methods have the disadvantages of low freezing efficiency and generation of large ice crystals, leading to possible damage of food quality. Power ultrasound assisted freezing as a novel technique can effectively reduce the adverse effects during freezing process. This paper gives an overview on recent researches of power ultrasound technique to accelerate the food freezing processes and illustrates the main principles of power ultrasound assisted freezing. The effects of power ultrasound on liquid food, model solid food as well as fruit and vegetables are discussed, respectively, from the aspects of increasing freezing rate and improving microstructure. It is shown that ultrasound assisted freezing can effectively improve the freezing efficiency and promote the formation of small and evenly distributed ice crystals, resulting in better food quality. Different inherent properties of food samples affect the effectiveness of ultrasound application and optimum ultrasound parameters depend on the nature of the samples. The application of ultrasound to the food industry is more likely on certain types of food products and more efforts are still needed to realize the industrial translation of laboratory results.

Physico-mechanical properties of naphthalene-acenaphthene eutectic system by different modes of solidification

International Nuclear Information System (INIS)

Sharma, B.L.; Gupta, S.; Tandon, S.; Kant, R.

2008-01-01

Anisotropic crystal growth kinetics from compositional melts encompassing the entire naphthalene-acenaphthene eutectic system, evidentially, evinces the dislocation mechanism. Rheological properties of eutectic phase melts at different temperatures explore the occurrence of molecular interactions emanating molecular clusters, rich in one phase or the other, in the eutectic melt. Microscopic studies confirm the crystalline faceted-faceted structure of the naphthalene-acenaphthene eutectic system. Implicit in the present work is the concept of strength-growth relationship that follows an identical form of the Weibull probability distribution curve. The curve exhibits two cut-off points corresponding to a lower strength limit in the slow and fast growth regions, and an upper strength limit in the moderate growth region. Relational essence between microstructural parameters essentially structuring morphology and excess thermodynamic functions implicitly governing molten state of the naphthalene-acenaphthene eutectic system is extracted

Quality by design in formulation and process development for a freeze-dried, small molecule parenteral product: a case study.

Science.gov (United States)

Mockus, Linas N; Paul, Timothy W; Pease, Nathan A; Harper, Nancy J; Basu, Prabir K; Oslos, Elizabeth A; Sacha, Gregory A; Kuu, Wei Y; Hardwick, Lisa M; Karty, Jacquelyn J; Pikal, Michael J; Hee, Eun; Khan, Mansoor A; Nail, Steven L

2011-01-01

A case study has been developed to illustrate one way of incorporating a Quality by Design approach into formulation and process development for a small molecule, freeze-dried parenteral product. Sodium ethacrynate was chosen as the model compound. Principal degradation products of sodium ethacrynate result from hydrolysis of the unsaturated ketone in aqueous solution, and dimer formation from a Diels-Alder condensation in the freeze-dried solid state. When the drug crystallizes in a frozen solution, the eutectic melting temperature is above -5°C. Crystallization in the frozen system is affected by pH in the range of pH 6-8 and buffer concentration in the range of 5-50 mM, where higher pH and lower buffer concentration favor crystallization. Physical state of the drug is critical to solid state stability, given the relative instability of amorphous drug. Stability was shown to vary considerably over the ranges of pH and buffer concentration examined, and vial-to-vial variability in degree of crystallinity is a potential concern. The formulation design space was constructed in terms of pH and drug concentration, and assuming a constant 5 mM concentration of buffer. The process design space is constructed to take into account limitations on the process imposed by the product and by equipment capability.

Crystallization of nodular cast iron with carbides

Directory of Open Access Journals (Sweden)

S. Pietrowski

2008-12-01

Full Text Available In this paper a crystallization process of nodular cast iron with carbides having a different chemical composition have been presented. It have been found, that an increase of molybdenum above 0,30% causes the ledeburutic carbides crystallization after (γ+ graphite eutectic phase crystallization. When Mo content is lower, these carbides crystallize as a pre-eutectic phase. In this article causes of this effect have been given.

Three-Dimensional Microstructure of Biological Tissues during Freezing and Thawing

Science.gov (United States)

Ishiguro, Hiroshi; Horimizu, Takashi; Kataori, Akinobu; Kajigaya, Hiroshi

Three-dimensional behavior of ice crystals and cells during the freezing and thawing of biological tissues was investigated microscopically in real time by using a confocal laser scanning microscope(CLSM) and a fluorescent dye, acridine orange (AO). Fresh tender meat (2nd pectoral muscles) of chicken was stained with the AO in physiological saline to distinguish ice crystals and cells by their different colors, and then frozen and thawed under two different thermal protocols: a) slow-cooling and rapid-warming and b) rapid-cooling and rapid-warming. The CLSM noninvasively produced optical tomograms of the tissues to clarify the pattern of freezing, morphology of ice crystals in the tissues, and the interaction between ice crystals and cells. Also, the tissues were morphologically investigated by pathological means after the freezing and thawing. Typical freezing pattern during the slow-cooling was extracellular-freezing, and those during the rapid-cooling were extracellular-freezing and intracellular freezing with a lot of fine ice crystals in the cells. Cracks caused by the extracellular and intracellular ice crystals remained in the muscle tissues after the thawing. The results obtained by using the CLSM/dye method were consistent with pathologically morphological changes in the tissues through freezing and thawing.

Treatment of Molybdate Containing Waste Streams

NARCIS (Netherlands)

Witkamp, G.J.; Van Spronsen, J.; Hasselaar, M.

2008-01-01

The invention is directed to a process for the treatment of an aqueous solution comprising sodium carbonate and/or sodium bicarbonate and sodium molybdate, said process comprising freeze crystallising the solution at the eutectic freezing point thereof and recovering substantially pure ice crystals,

Transition from natural-convection-controlled freezing to conduction-controlled freezing

International Nuclear Information System (INIS)

Sparrow, E.M.; Ramsey, J.W.; Harris, J.S.

1981-01-01

Experiments were performed to study the transition between freezing controlled by natural convection in the liquid adjacent to a freezing interface and freezing controlled by heat conduction in the solidified material. The freezing took place on a cooled vertical tube immersed in an initially superheated liquid contained in an adiabatic-walled vessel. At early and intermediate times, temperature differences throughout the liquid induce a vigorous natural convection motion which retards freezing, but the temperature differences diminish with time and natural convection ebbs. At large times, the freezing rate is fully controlled by heat conduction in the solidified material. The frozen specimens for short and intermediate freezing times are smooth-surfaced and tapered, while those for large times are straight-sided and have surfaces that are overlaid with a thicket of large discrete crystals. These characteristics correspond respectively to those of natural-convection- controlled freezing and conduction-controlled freezing. At early times, the measured mass of the frozen material is identical to that for natural-convection-controlled freezing and conduction-controlled freezing. At early times, the measured mass of the frozen material is identical to that for natural-convection-controlled freezing. At later times, the frozen mass tends to approach that for conduction-controlled freezing, but a residual deficit remains

On the relation between primary and eutectic solidification structures in gray iron

International Nuclear Information System (INIS)

Elmquist, L; Sonawane, P A

2012-01-01

The solidification of hypoeutectic gray cast iron starts with the nucleation of primary austenite crystals. Before graphite is nucleated, and the eutectic structure is formed, these crystals start to grow as columnar or equiaxed dendrites. However, very little is known about these dendrites, and especially how they influence the subsequent eutectic structure. Besides, it has previously been shown that the primary solidification structure influences the formation of defects. Shrinkage porosity was found between the dendrites, in the grain boundaries, and the formation of the primary solidification structure was found to influence problems related to metal expansion penetration. Therefore a better understanding about the formation of this structure is of importance. In this work, different inoculants and their influence on the formation of the micro- and macrostructures has been investigated. The inoculants considered are commercially used inoculants, i.e. inoculants used in the foundries, as well as different iron powders. The addition of iron powder is used to promote the primary solidification structure. It is shown that the nucleation of the dendrites is influenced by the amount of iron powder. Secondary dendrite arm spacing is a quantitative measurement in the microstructure related to these dendrites, which in turn depends on the solidification time. Eutectic cell size, on the other hand, is found to depend on secondary dendrite arm spacing. It is shown how the addition of inoculants influences both primary and eutectic solidification structures, and how they are related to each other.

Basic visualization experiments on eutectic reaction of boron carbide and stainless steel under sodium-cooled fast reactor conditions

International Nuclear Information System (INIS)

Yamano, Hidemasa; Suzuki, Tohru; Kamiyama, Kenji; Kudo, Isamu

2016-01-01

This paper describes basic visualization experiments on eutectic reaction and relocation of boron carbide (B 4 C) and stainless steel (SS) under a high temperature condition exceeding 1500degC as well as the importance of such behaviors in molten core during a core disruptive accident in a Generation-IV sodium-cooled fast reactor (750 MWe class) designed in Japan. At first, a reactivity history was calculated using an exact perturbation calculation tool taking into account expected behaviors. This calculation indicated the importance of a relocation behavior of the B 4 C-SS eutectic because its behavior has a large uncertainty in the reactivity history. To clarify this behavior, basic experiments were carried out by visualizing the reaction of a B 4 C pellet contacted with molten SS in a high temperature-heating furnace. The experiments have shown the eutectic reaction visualization as well as freezing and relocation of the B 4 C-SS eutectic in upper part of the solidified test piece due to the density separation. (author)

Nucleation-controlled microstructures and anomalous eutectic formation in undercooled Co-Sn and Ni-Si eutectic melts

Science.gov (United States)

Li, Mingjun; Kuribayashi, Kazuhiko

2003-12-01

Co-20.5 at. pct Sn and Ni-21.4 at. pct Si eutectic alloys have been levitated and undercooled in an electromagnetic levitator (EML) and then solidified spontaneously at different undercoolings. The original surface and cross-sectional morphologies of these solidified samples consist of separate eutectic colonies regardless of melt undercooling, indicating that microstructures in the free solidification of the eutectic systems are nucleation controlled. Regular lamellae always grow from the periphery of an independent anomalous eutectic grain in each eutectic colony. This typical morphology shows that the basic unit should be a single eutectic colony, when discussing the solidification behavior. Special emphasis is focused on the anomalous eutectic formation after a significant difference in linear kinetic coefficients is recognized for terminal eutectic phases, in particular when a eutectic reaction contains a nonfaceted disordered solid solution and a faceted ordered intermetallic compound as the terminal eutectic phases. It is this remarkable difference in the linear kinetic coefficients that leads to a pronounced difference in kinetic undercoolings. The sluggish kinetics in the interface atomic attachment of the intermetallic compound originates the occurrence of the decoupled growth of two eutectic phases. Hence, the current eutectic models are modified to incorporate kinetic undercooling, in order to account for the competitive growth behavior of eutectic phases in a single eutectic colony. The critical condition for generating the decoupled growth of eutectic phases is proposed. Further analysis reveals that a dimensionless critical undercooling may be appropriate to show the tendency for the anomalous eutectic-forming ability when considering the difference in linear kinetic coefficients of terminal eutectic phases. This qualitative criterion, albeit crude with several approximations and assumptions, can elucidate most of the published experimental results

Pressure-induced structural change in liquid GaIn eutectic alloy

DEFF Research Database (Denmark)

Yu, Q.; Ahmad, A. S.; Ståhl, Kenny

2017-01-01

Synchrotron x-ray diffraction reveals a pressure induced crystallization at about 3.4 GPa and a polymorphic transition near 10.3 GPa when compressed a liquid GaIn eutectic alloy up to ~13 GPa at room temperature in a diamond anvil cell. Upon decompression, the high pressure crystalline phase...

Effect of freezing temperature on the color of frozen salmon.

Science.gov (United States)

Ottestad, Silje; Enersen, Grethe; Wold, Jens Petter

2011-09-01

New freezing methods developed with the purpose of improved product quality after thawing can sometimes be difficult to get accepted in the market. The reason for this is the formation of ice crystals that can give the product a temporary color loss and make it less appealing. We have here used microscopy to study ice crystal size as a function of freezing temperature by investigating the voids in the cell tissue left by the ice crystals. We have also investigated how freezing temperature affects the color and the visible absorption spectra of frozen salmon. Freezing temperatures previously determined to be the best for quality after thawing (-40 to -60 °C) were found to cause a substantial loss in perceived color intensity during frozen state. This illustrated the conflict between optimal freezing temperatures with respect to quality after thawing against visual appearance during frozen state. Low freezing temperatures gave many small ice crystals, increased light scattering and an increased absorption level for all wavelengths in the visible region. Increased astaxanthin concentration on the other hand would give higher absorption at 490 nm. The results showed a clear potential of using visible interactance spectroscopy to differentiate between poor product coloration due to lack of pigmentation and temporary color loss due to light scattering by ice crystal. This type of measurements could be a useful tool in the development of new freezing methods and to monitor ice crystal growth during frozen storage. It could also potentially be used by the industry to prove good product quality. In this article we have shown that freezing food products at intermediate to low temperatures (-40 to -80 °C) can result in paler color during frozen state, which could affect consumer acceptance. We have also presented a spectroscopic method that can separate between poor product color and temporary color loss due to freezing. © 2011 Institute of Food Technologists®

Eutectic crystallization behavior of new Zr48Cu36Al8Ag8 alloy with high glass-forming ability

International Nuclear Information System (INIS)

Zhang, Q S; Zhang, W; Xie, G Q; Inoue, A

2009-01-01

A water quenching method is used to produce as-cast Zr 48 Cu 36 Al 8 Ag 8 rods with diameters from 20 mm to 25 mm. The microstructures of the as-cast samples were investigated by X-ray diffraction, optical microscopy and scanning electron microscopy. Furthermore, the crystallization behavior of the Zr 48 Cu 36 Al 8 Ag 8 glassy alloy was examined by XRD and transmission electron microscopy. Based on the results obtained one can assume that the simultaneous precipitation of the Zr 2 Cu+AlCu 2 Zr eutectic phases is the possible reason for the high stabilization of the quaternary Zr 48 Cu 36 Al 8 Ag 8 supercooled liquid.

Key composition optimization of meat processed protein source by vacuum freeze-drying technology.

Science.gov (United States)

Ma, Yan; Wu, Xingzhuang; Zhang, Qi; Giovanni, Vigna; Meng, Xianjun

2018-05-01

Vacuum freeze-drying technology is a high technology content, a wide range of knowledge of technology in the field of drying technology is involved, it is also a method of the most complex drying equipment, the largest energy consumption, the highest cost of drying method, but due to the particularity of its dry goods: the freeze-drying food has the advantages of complex water performance is good, cooler and luster of freezing and drying food to maintain good products, less nutrient loss, light weight, easy to carry transportation, easy to long-term preservation, and on the quality is far superior to the obvious advantages of other dried food, making it become the forefront of drying technology research and development. The freeze-drying process of Chinese style ham and western Germany fruit tree tenderloin is studied in this paper, their eutectic point, melting point and collapse temperature, freeze-drying curve and its heat and mass transfer characteristics are got, then the precool temperature and the highest limiting temperature of sublimation interface are determined. The effect of system pressure on freeze-dried rate in freeze-drying process is discussed, and the method of regulating pressure circularly is determined.

Freezing of perchlorate and chloride brines under Mars-relevant conditions

Science.gov (United States)

Primm, K. M.; Gough, R. V.; Chevrier, V. F.; Tolbert, M. A.

2017-09-01

Perchlorate and chloride salts on Mars could readily absorb water vapor and deliquesce into aqueous solutions. The deliquescence relative humidity (RH) as well as the efflorescence (recrystallization) RH of several Mars-relevant salts are now well known; however, the conditions that could cause a brine to freeze are not well established. It is often assumed that ice formation will occur whenever the saturation with respect to ice, Sice, of the system is greater than or equal to unity; however, ice nucleation is often hindered due to a kinetic barrier. For ice to form, a critical cluster of the ice crystal must first be achieved, often requiring Sice > 1. Here we use a Raman microscope and an environmental cell to examine the RH and temperature conditions required for Mg(ClO4)2 and MgCl2 brines to freeze into ice. By examining the salt phase present both optically and spectrally under different low temperature conditions, it is found that both salts exhibit Sice values much greater than unity, meaning that supersaturation readily occurs and brines can persist under conditions previously thought to lead to freezing. The RH range of ice formation for Mg(ClO4)2 from 218 to 245 K is 83-95%, respectively, corresponding to Sice = 1.30-1.54. The RH of ice formation for MgCl2 ranges from 80 to 100% for temperatures between 221 and 252 K, corresponding to Sice = 1.30-1.35. In addition to ice nucleation, the deliquescence and efflorescence relative humidity values for MgCl2 were determined. Two hydrates for MgCl2 were observed, and exhibited different deliquescence relative humidity (DRH) values. The DRH for MgCl2·4H2O was found to be 12.8 ± 0.3% at 243 K with slightly increasing DRH as temperature decreased. The DRH for MgCl2·6H2O was found to be 31.3 ± 0.6% at 242 K with little temperature dependence. The DRH of MgCl2·6H2O was measured below the previously reported eutectic, 240 K, suggesting that the eutectic might be incorrect or that there is a different relevant

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

Science.gov (United States)

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

2014-01-01

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

Raman mapping in the elucidation of solid salt eutectic and near eutectic structures

DEFF Research Database (Denmark)

Berg, Rolf W.; Kerridge, D. H.

2002-01-01

The distribution of the different components of solidified eutectic or near-eutectic salt mixtures (eutectics) was examined by use of Raman microscope mapping of the structures formed when these melts were slowly cooled. Seven binary and one ternary system were investigated. In most cases...... and the composition. When unidirectional cooling was applied it was possible for the system (KCl-Na2SO4, 60:40 mol/mol) to observe lamellar arrangements of the component phases, in an arrangement closely similar to what is frequently found among metallic or ceramic eutectics. Each area, conglomerate or lamellar, did...

Key composition optimization of meat processed protein source by vacuum freeze-drying technology

Directory of Open Access Journals (Sweden)

Yan Ma

2018-05-01

Full Text Available Vacuum freeze-drying technology is a high technology content, a wide range of knowledge of technology in the field of drying technology is involved, it is also a method of the most complex drying equipment, the largest energy consumption, the highest cost of drying method, but due to the particularity of its dry goods: the freeze-drying food has the advantages of complex water performance is good, cooler and luster of freezing and drying food to maintain good products, less nutrient loss, light weight, easy to carry transportation, easy to long-term preservation, and on the quality is far superior to the obvious advantages of other dried food, making it become the forefront of drying technology research and development. The freeze-drying process of Chinese style ham and western Germany fruit tree tenderloin is studied in this paper, their eutectic point, melting point and collapse temperature, freeze-drying curve and its heat and mass transfer characteristics are got, then the precool temperature and the highest limiting temperature of sublimation interface are determined. The effect of system pressure on freeze-dried rate in freeze-drying process is discussed, and the method of regulating pressure circularly is determined. Keywords: Ham, Tenderloin, Vacuum freeze-dry, Processing, Optimization

Hydrostatic Pressure Study on 3-K Phase Superconductivity in Sr2RuO4-Ru Eutectic Crystals by AC Magnetic Susceptibility Measurements

International Nuclear Information System (INIS)

Yaguchi, Hiroshi; Watanabe, Hiromichi; Sakaue, Akira

2012-01-01

We have investigated the effect of hydrostatic pressure on 3-K phase superconductivity in Sr 2 RuO 4 -Ru eutectic crystals by means of AC magnetic susceptibility measurements. We have found that the application of hydrostatic pressure suppresses the superconducting transition temperature T c of the 3-K phase with a pressure coefficient of dT c /dP ≈ −0.2 K/GPa, similar to the case of the 1.5-K phase. We have also observed that the effect of hydrostatic pressure on the 3-K phase seems to be elastic whilst that of uniaxial pressure is plastic.

Evaluation and modeling of the eutectic composition of various drug-polyethylene glycol solid dispersions.

Science.gov (United States)

Baird, Jared A; Taylor, Lynne S

2011-06-01

The purpose of this study was to gain a better understanding of which factors contribute to the eutectic composition of drug-polyethylene glycol (PEG) blends and to compare experimental values with predictions from the semi-empirical model developed by Lacoulonche et al. Eutectic compositions of various drug-PEG 3350 solid dispersions were predicted, assuming athermal mixing, and compared to experimentally determined eutectic points. The presence or absence of specific interactions between the drug and PEG 3350 were investigated using Fourier transform infrared (FT-IR) spectroscopy. The eutectic composition for haloperidol-PEG and loratadine-PEG solid dispersions was accurately predicted using the model, while predictions for aceclofenac-PEG and chlorpropamide-PEG were very different from those experimentally observed. Deviations in the model prediction from ideal behavior for the systems evaluated were confirmed to be due to the presence of specific interactions between the drug and polymer, as demonstrated by IR spectroscopy. Detailed analysis showed that the eutectic composition prediction from the model is interdependent on the crystal lattice energy of the drug compound (evaluated from the melting temperature and the heat of fusion) as well as the nature of the drug-polymer interactions. In conclusion, for compounds with melting points less than 200°C, the model is ideally suited for predicting the eutectic composition of systems where there is an absence of drug-polymer interactions.

General characteristics of eutectic alloy solidification mechanisms

International Nuclear Information System (INIS)

Lemaignan, Clement.

1977-01-01

The eutectic alloy sodification was studied in binary systems: solidification of non facetted - non facetted eutectic alloy (theoretical aspects, variation of the lamellar spacing, crystallographic relation between the various phases); solidification of facetted - non facetted eutectic alloy; coupled growth out of eutectic alloy; eutectic nucleation [fr

A New Freezing Method Using Pre-Dehydration by Microwave-Vacuum Drying

Science.gov (United States)

Tsuruta, Takaharu; Hamidi, Nurkholis

Partial dehydration by microwave-vacuum drying has been applied to tuna and strawberry in order to reduce cell-damages caused by the formation of large ice-crystals during freezing. The samples were subjected to microwave vacuum drying at pressure of 5 kPa and temperature less than 27°C to remove small amount of water prior to freezing. The tuna were cooled by using the freezing chamber at temperature -50°C or -150°C, while the strawberries were frozen at temperature -30°C or -80°C, respectively. The temperature transients in tuna showed that removing some water before freezing made the freezing time shorter. The observations of ice crystal clearly indicated that rapid cooling and pre-dehydration prior to freezing were effective in minimizing the size of ice crystal. It is also understood that the formation of large ice crystals has a close relation to the cell damages. After thawing, the observation of microstructure was done on the tuna and strawberry halves. The pre-dehydrated samples showed a better structure than the un-dehydrated one. It is concluded that the pre-dehydration by microwave-vacuum drying is one promising method for the cryo-preservation of foods.

Screening of additives for the production of ice pulp for application in normal cooling and freezing; Screening von Zusatzstoffen zur Herstellung von Eisbrei fuer die NK-/TK-Anwendung

Energy Technology Data Exchange (ETDEWEB)

Ruebeling, Jascha; Eiseler, Jens [Hochschule Karlsruhe - Technik und Wirtschaft (Germany). Inst. fuer Kaelte-, Klima- und Umwelttechnik

2011-07-01

The project investigated non-toxic additives for production of ice slurry. Ice slurry is an environment-friendly refrigerant that is increasingly used as a substitute for conventional refrigerants. In view of rising energy prices and an impending tax on climate-relevant refrigerants, ice slurry may soon be used for chilling of food in supermarkets. For this, ice slurry of about 0 C is required for normal cooling and of about -25 C for deep freezing. A very fine-grained, pumpable ice slurry is obtained with glucose as an additive, or with sodium chloride in eutectic concentration with small amounts of ethanol for deep freezing. Ethanol will refine the coarse crystal structure of the eutectic sodium chloride / water mixture and will also reduce the freezing point. Further, the method of primary crystallisation on a crystallised additive was developed. An industrial plant working by this principle will have less disturbances and wear during ice slurry production. [German] Die Projektarbeit befasste sich mit der Untersuchung lebensmittelvertraeglicher Additive zur Herstellung von Eisbrei. Eisbrei gilt als umweltfreundlicher Kaeltetraeger, der zunehmend in verschiedenen Bereichen zur Anwendung kommt und herkoemmliche Kaeltemittel ersetzen kann. Aufgrund steigender Energiekosten sowie einer eventuell anstehenden Besteuerung treibhauswirksamer Kaeltemittel, kann Eisbrei zukuenftig zur Kuehlung von Lebensmitteln in Supermaerkten verwendet werden. Dazu wird Eisbrei mit ca. 0 C fuer die Normalkuehlung, beziehungsweise mit ca. -25 C fuer die Tiefkuehlung benoetigt. Mit Glucose als Zusatzstoff laesst sich ein sehr feinkoerniger und damit pumpbarer Eisbrei fuer die Normalkuehlung erzeugen. Bei der Tiefkuehlung ist Natriumchlorid in einer eutektischen Konzentration mit geringen Mengen Ethanol empfehlenswert. Ethanol verfeinert die grobe Kristallstruktur des reinen eutektischen Natriumchlorid-Wasser-Gemisches und senkt den Gefrierpunkt. Des Weiteren wurde das Verfahren der

Tunable colorimetric performance of Al{sub 2}O{sub 3}-YAG:Ce{sup 3+} eutectic crystal by Ce{sup 3+} concentration

Energy Technology Data Exchange (ETDEWEB)

Sai, Qinglin, E-mail: saiql@siom.ac.cn; Xia, Changtai, E-mail: xia_ct@siom.ac.cn

2017-06-15

Ce-doped Al{sub 2}O{sub 3}-YAG eutectics with different percentage of Ce were successfully grown by the optical floating zone technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structure. The results show that they have typical eutectic structure of interpenetrating sapphire and garnet phases with the tens of microns lamella spacing. The photoluminescence spectra of the eutectics showed that they have wide excitation band, and samples with 1.6 mol% Ce-doped has the highest emission intensity. The eutectic-packaged LED has high luminous efficiency and its color can be modulated by changing Ce concentration. The results reveal that Ce-doped Al{sub 2}O{sub 3}-YAG eutectic is a promising phosphor for white LED applications.

Freezing Range, Melt Quality, and Hot Tearing in Al-Si Alloys

Science.gov (United States)

Uludağ, Muhammet; Çetin, Remzi; Dispinar, Derya

2018-02-01

In this study, three different aluminum-silicon alloys (A356, A413, and A380) that have different solidification morphology and solidification ranges were examined with an aim to evaluate the hot tearing susceptibility. T-shape mold and Constrained Rod Casting (CRC) mold were used for the characterization. Reduced Pressure Test (RPT) was used to quantify the casting quality by measuring bifilm index. It was found that bifilm index and solidification range have an important role on the hot tearing formation. As it is known, bifilms can cause porosity and in this case, it was shown that porosity formed by bifilms decreased hot tearing tendency. As the freezing range of alloy increases, bifilms find the time to unravel that reduces hot tearing. However, for eutectic alloy (A413), due to zero freezing range, regardless of bifilm content, hot tearing was never observed. A380.1 alloy had the highest tendency for hot tearing due to having the highest freezing range among the alloys investigated in this work.

Vertical gradient freeze of 4 inch Ge crystals in a heater-magnet module

Science.gov (United States)

Frank-Rotsch, Ch.; Rudolph, P.

2009-04-01

For the first time 4-in. Ge single crystals were grown using the vertical gradient freeze technique (VGF) in a traveling magnetic field (TMF) generated in a heater-magnet module (HMM). The HMM was placed closely around the growth container inside the chamber of the industrial Bridgman equipment "Kronos". The HMM generates heat and a TMF together. It has a coil-shaped design and replaces the standard meander-type heater. Direct current (DC) for heat production and out-of-phase-accelerated currents (AC) for TMF generation were simultaneously delivered to three equally spaced coil segments connected by star-type wiring. In order to achieve a nearly flat and slightly convex growing interface the AC amplitude, frequency and phase shift have been optimized numerically by using the 3D CrysMAS code and validated by striation analysis on as-grown crystals. Low-field frequencies in the range f=20-50 Hz proved to be of most suitable condition. TMF programming is required to obtain constant interface morphology over the whole growth run. First Ge single crystals grown under nearly optimal conditions show reduced macro- and micro-inhomogeneities, relatively low dislocation density of (3-10)×10 2 cm -2, and high carrier mobility of μp=2800 cm 2 V -1 s -1.

Investigation of the Behavior of the Co C Eutectic Fixed Point

Science.gov (United States)

Girard, F.; Battuello, M.; Florio, M.

2007-12-01

The behavior of the Co C eutectic fixed point was investigated at INRIM. Several cells of different design and volume, and filled with cobalt of different purity were constructed and investigated with both Pt/Pd thermocouples and radiation thermometers. The melting behavior was investigated with respect to the melting rate, the pre-freezing rate, and the annealing time. The melting temperatures, as defined, were not significantly affected by the different testing conditions, even if the shape and duration of the plateaux were influenced. Several tens of melt and freeze cycles were performed with the different cells. The spread in the results for all of the different conditions was very limited in extent, giving rise to a standard deviation of less than 0.04 °C; a repeatability of better than 0.02 °C was found with both Pt/Pd thermocouples and radiation thermometers. The results of our measurements are encouraging and confirm the suitability of Co C as a reference point for the high-temperature range in a possible future temperature scale. Investigations of long-term stability remain ongoing.

Microstructure Of MnBi/Bi Eutectic Alloy

Science.gov (United States)

Wilcox, William R.; Eisa, G. F.; Baskaran, B.; Richardson, Donald C.

1988-01-01

Collection of three reports describes studies of directional solidification of MnBi/Bi eutectic alloy. Two of the reports, "Influence of Convection on Lamellar Spacing of Eutectics" and "Influence of Convection on Eutectic Microstructure," establish theoretical foundation for remaining document. Reports seek to quantify effect of convection on concentration field of growing lamellar eutectic. Remaining report, "Study of Eutectic Formation," begins by continuing theoretical developments. New technique under development by one of the authors helps to reveal three-dimensional microstructures of alloys.

Top-down freezing in a Fe-FeS core and Ganymede's present-day magnetic field

Science.gov (United States)

Rückriemen, Tina; Breuer, Doris; Spohn, Tilman

2018-06-01

Ganymede's core most likely possesses an active dynamo today, which produces a magnetic field at the surface of ∼ 719 nT. Thermochemical convection triggered by cooling of the core is a feasible power source for the dynamo. Experiments of different research groups indicate low pressure gradients of the melting temperatures for Fe-FeS core alloys at pressures prevailing in Ganymede's core ( < 10 GPa). This may entail that the core crystallizes from the top instead of from the bottom as is expected for Earth's core. Depending on the core sulfur concentration being more iron- or more sulfur-rich than the eutectic concentration either snowing iron crystals or a solid FeS layer can form at the top of the core. We investigate whether these two core crystallization scenarios are capable of explaining Ganymede's present magnetic activity. To do so, we set up a parametrized one-dimensional thermal evolution model. We explore a wide range of parameters by running a large set of Monte Carlo simulations. Both freezing scenarios can explain Ganymede's present-day magnetic field. Dynamos of iron snow models are rather young ( < 1 Gyr), whereas dynamos below the FeS layer can be both young and much older ( ∼ 3.8 Gyr). Successful models preferably contain less radiogenic heat sources in the mantle than the chondritic abundance and show a correlation between the reference viscosity in the mantle and the initial core sulfur concentration.

Freeze desalination of seawater using LNG cold energy

KAUST Repository

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

2016-01-01

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.

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.

Preparation and Thermal Properties of Eutectic Hydrate Salt Phase Change Thermal Energy Storage Material

OpenAIRE

Liang, Lin; Chen, Xi

2018-01-01

In this study, a new cold storage phase change material eutectic hydrate salt (K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O) was prepared, modified, and tested. The modification was performed by adding a nucleating agent and thickener. The physical properties such as viscosity, surface tension, cold storage characteristics, supercooling, and the stability during freeze-thaw cycles were studied. Results show that the use of nucleating agents, such as sodium tetraborate, sodium fluoride, and nanoparti...

The growth of faceted/nonfaceted eutectics

International Nuclear Information System (INIS)

Suchtelen, J. van

1976-01-01

This paper is concerned with the unidirectional solidification of eutectic melts in which one of the phases has a faceted, the other a nonfaceted solid-liquid interface. The occurrence of complex microstructures in such eutectics is explained as a growth phenomenon. The essential condition for the occurrence of such structures is a non-isothermal solid-liquid interface, developing into a faceted-cellular structure. The faceted shape of the cells is imposed by the faceted component of the eutectic. Breakdown to such a cellular structure occurs not only in constitutional-supercooling conditions, but under any circumstances, the cellular period being a function of growth velocity, temperature gradient etc. The two-phase morphology of the eutectic structure is discussed in terms of the relative magnitude of the periods of the cellular and of the eutectic structure. (orig.) [de

Assessing the thermal performance of three cold energy storage materials with low eutectic temperature for food cold chain

International Nuclear Information System (INIS)

Li, Yu-Chu M.; Chen, Yen-Hong A.

2016-01-01

Development a novel inorganic salt eutectic solution for cold energy storage material (ESM) have succeeded conducted in this study. The eutectic solutions shows a low melting temperature and high latent heat of fusion value as effect of addition nano copper powder into the eutectic solution. We report a new simulation technique of thermal property as well as test results of three inorganic salts. The thermal property of three inorganic salts were simulated using the differential scanning calorimetry (DSC) method with the help of three binary phase diagrams. The simulation shows the liquidus temperature of each binary phase diagram conforming nicely to the theoretical prediction of the Gibbs-Duhem equation. In order to predict cold storage keeping time, we derived a heat transfer model based on energy conservation law. Three ESMs were tested for their cold energy storage performance and thermal properties aging for durability. The empirical results indicate that, for food cold chain, the melting point rule is superior with less deviation. With this information, one can pre-estimate the basic design parameters with great accuracy; the cost of design and development for a new cold storage logistics system can be dramatically reduced. - Highlights: • For these three ESMs, their modified values of melting point and latent heat are presented in Table 2. • But, TC is usually not a constant like TE. • The freezing time underwent a drop ∼10% in the binary eutectic region.

Examination of Clustering in Eutectic Microstrcture

Directory of Open Access Journals (Sweden)

Bortnyik K.

2017-06-01

Full Text Available The eutectic microstructures are complex microstructures and a hard work to describe it with few numbers. The eutectics builds up eutectic cells. In the cells the phases are clustered. With the development of big databases the data mining also develops, and produces a lot of method to handling the large datasets, and earns information from the sets. One typical method is the clustering, which finds the groups in the datasets. In this article a partitioning and a hierarchical clustering is applied to eutectic structures to find the clusters. In the case of AlMn alloy the K-means algorithm work well, and find the eutectic cells. In the case of ductile cast iron the hierarchical clustering works better. With the combination of the partitioning and hierarchical clustering with the image transformation, an effective method is developed for clustering the objects in the microstructures.

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)

Material properties influence on steam explosion efficiency. Prototypic versus simulant melts, eutectic versus non-eutectic melts

International Nuclear Information System (INIS)

Leskovar, M.; Mavko, B.

2006-01-01

A steam explosion may occur during a severe nuclear reactor accident if the molten core comes into contact with the coolant water. A strong enough steam explosion in a nuclear power plant could jeopardize the containment integrity and so lead to a direct release of radioactive material to the environment. Details of processes taking place prior and during the steam explosion have been experimentally studied for a number of years with adjunct efforts in modelling these processes to address the scaling of these experiments. Steam explosion experiments have shown that there are important differences of behaviour between simulant and prototypical melts, and that also at prototypical melts the fuel coolant interactions depend on the composition of the corium. In experiments with prototypic materials no spontaneous steam explosions occurred (except with an eutectic composition), whereas with simulant materials the steam explosions were triggered spontaneously. The energy conversion ratio of steam explosions with prototypic melts is at least one order of magnitude lower than the energy conversion ratio of steam explosions with simulant melts. Although the different behaviour of prototypic and simulant melts has been known for a number of years, there is no reliable explanation for these differences. Consequently it is not possible to reliably estimate whether corium would behave so non-explosive also in reactor conditions, where the mass of poured melt is nearly three orders of magnitude larger than in experimental conditions. An even more fascinating material effect was observed recently at corium experiments with eutectic and non-eutectic compositions. It turned out that eutectic corium always exploded spontaneously, whereas non-eutectic corium never exploded spontaneously. In the paper, a possible explanation of both material effects (prototypic/simulant melts, eutectic/non-eutectic corium) on the steam explosion is provided. A model for the calculation of the

Crystallization and structure of chromium cast iron with addition of Mo and Ni

International Nuclear Information System (INIS)

Pietrowski, S.

1998-01-01

The aim of the presented paper is to show the results of examination of the crystallization process using the method of thermal-derivative analysis (ATD) and the structure examination of chromium cast iron, chromium molybdenum c. i. and chromium molybdenum nickel c.i. It was found that molybdenum in amount over 2 wt % causes the crystallization of eutectic carbides M 23 C 6 and M 6 C. The M 23 C 6 carbide crystallizes upon the crystallization of eutectic carbides M 3 C and M 7 C 3 . It is shown that ATD method facilitates both interpretation and control of the crystallization as well as formation of the cast iron structure at the solid state. (author)

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

Modelling Eutectic Growth in Unmodified and Modified Near-Eutectic Al-Si Alloy

DEFF Research Database (Denmark)

Tiedje, Niels Skat; Hattel, Jesper Henri; Taylor, John A.

2013-01-01

growth parameters from the literature that depend on the type of modification (unmodified, Na-modified or Sr-modified) are used to describe differences in growth of the alloys. Modelling results are compared with solidification experiments where an Al-12.5wt%Si alloy was cast in unmodified, Na modified......A numerical model that describes solidification of primary aluminium grains and nucleation and growth of eutectic cells is used to analyse the solidification of an Al-12.5wt% Si alloy. Nucleation of eutectic cells is modelled using an Oldfield-type nucleation model where the number of nuclei...... and Sr modified forms. The model confirms experimental observations of how modification and alloy composition influence nucleation, growth and finally the size of eutectic cells in the alloys. Modelling results are used to explain how cooling conditions in the casting act together with the nuclei density...

Application of the Quality by Design Approach to the Freezing Step of Freeze-Drying: Building the Design Space.

Science.gov (United States)

Arsiccio, Andrea; Pisano, Roberto

2018-06-01

The present work shows a rational method for the development of the freezing step of a freeze-drying cycle. The current approach to the selection of freezing conditions is still empirical and nonsystematic, thus resulting in poor robustness of control strategy. The final aim of this work is to fill this gap, describing a rational procedure, based on mathematical modeling, for properly choosing the freezing conditions. Mechanistic models are used for the prediction of temperature profiles during freezing and dimension of ice crystals being formed. Mathematical description of the drying phase of freeze-drying is also coupled with the results obtained by freezing models, thus providing a comprehensive characterization of the lyophilization process. In this framework, deep understanding of the phenomena involved is required, and according to the Quality by Design approach, this knowledge can be used to build the design space. The step-by-step procedure for building the design space for freezing is thus described, and examples of applications are provided. The calculated design space is validated upon experimental data, and we show that it allows easy control of the freezing process and fast selection of appropriate operating conditions. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Bacterial Ice Crystal Controlling Proteins

Science.gov (United States)

Lorv, Janet S. H.; Rose, David R.; Glick, Bernard R.

2014-01-01

Across the world, many ice active bacteria utilize ice crystal controlling proteins for aid in freezing tolerance at subzero temperatures. Ice crystal controlling proteins include both antifreeze and ice nucleation proteins. Antifreeze proteins minimize freezing damage by inhibiting growth of large ice crystals, while ice nucleation proteins induce formation of embryonic ice crystals. Although both protein classes have differing functions, these proteins use the same ice binding mechanisms. Rather than direct binding, it is probable that these protein classes create an ice surface prior to ice crystal surface adsorption. Function is differentiated by molecular size of the protein. This paper reviews the similar and different aspects of bacterial antifreeze and ice nucleation proteins, the role of these proteins in freezing tolerance, prevalence of these proteins in psychrophiles, and current mechanisms of protein-ice interactions. PMID:24579057

Emerging techniques for assisting and accelerating food freezing processes: A review of recent research progresses.

Science.gov (United States)

Cheng, Lina; Sun, Da-Wen; Zhu, Zhiwei; Zhang, Zi

2017-03-04

Freezing plays an important role in food preservation and the emergence of rapid freezing technologies can be highly beneficial to the food industry. This paper reviews some novel food freezing technologies, including high-pressure freezing (HPF), ultrasound-assisted freezing (UAF), electrically disturbed freezing (EF) and magnetically disturbed freezing (MF), microwave-assisted freezing (MWF), and osmo-dehydro-freezing (ODF). HPF and UAF can initiate ice nucleation rapidly, leading to uniform distribution of ice crystals and the control of their size and shape. Specifically, the former is focused on increasing the degree of supercooling, whereas the latter aims to decrease it. Direct current electric freezing (DC-EF) and alternating current electric freezing (AC-EF) exhibit different effects on ice nucleation. DC-EF can promote ice nucleation and AC-EF has the opposite effect. Furthermore, ODF has been successfully used for freezing various vegetables and fruit. MWF cannot control the nucleation temperature, but can decrease supercooling degree, thus decreasing the size of ice crystals. The heat and mass transfer processes during ODF have been investigated experimentally and modeled mathematically. More studies should be carried out to understand the effects of these technologies on food freezing process.

Crystallization characteristics of cast aluminum alloys during a unidirectional solidification process

Energy Technology Data Exchange (ETDEWEB)

Okayasu, Mitsuhiro, E-mail: mitsuhiro.okayasu@utoronto.ca; Takeuchi, Shuhei

2015-05-01

The crystal orientation characteristics of cast Al–Si, Al–Cu and Al–Mg alloys produced by a unidirectional solidification process are examined. Two distinct crystal orientation patterns are observed: uniform and random formation. A uniform crystal orientation is created by columnar growth of α-Al dendrites in the alloys with low proportions of alloying element, e.g., the Al–Si alloy (with Si <12.6%) and the Al–Cu and Al–Mg alloys (with Cu and Mg <2%). A uniformly organized crystal orientation with [100] direction is created by columnar growth of α-Al dendrites. With increasing proportion of alloying element (>2% Cu or Mg), the uniform crystal orientations collapse in the Al–Cu and Al–Mg alloys, owing to interruption of the columnar α-Al dendrite growth as a result of different dynamics of the alloying atoms and the creation of a core for the eutectic phases. For the hypo-eutectic Al–Si alloys, a uniform crystal orientation is obtained. In contrast, a random orientation can be detected in the hyper-eutectic Al–Si alloy (15% Si), which results from interruption of the growth of the α-Al dendrites due to precipitation of primary Si particles. There is no clear effect of crystal formation on ultimate tensile strength (UTS), whereas crystal orientation does influence the material ductility, with the alloys with a uniform crystal orientation being elongated beyond their UTS points and with necking occurring in the test specimens. In contrast, the alloys with a nonuniform crystal orientation are not elongated beyond their UTS points.

Crystallization characteristics of cast aluminum alloys during a unidirectional solidification process

International Nuclear Information System (INIS)

Okayasu, Mitsuhiro; Takeuchi, Shuhei

2015-01-01

The crystal orientation characteristics of cast Al–Si, Al–Cu and Al–Mg alloys produced by a unidirectional solidification process are examined. Two distinct crystal orientation patterns are observed: uniform and random formation. A uniform crystal orientation is created by columnar growth of α-Al dendrites in the alloys with low proportions of alloying element, e.g., the Al–Si alloy (with Si <12.6%) and the Al–Cu and Al–Mg alloys (with Cu and Mg <2%). A uniformly organized crystal orientation with [100] direction is created by columnar growth of α-Al dendrites. With increasing proportion of alloying element (>2% Cu or Mg), the uniform crystal orientations collapse in the Al–Cu and Al–Mg alloys, owing to interruption of the columnar α-Al dendrite growth as a result of different dynamics of the alloying atoms and the creation of a core for the eutectic phases. For the hypo-eutectic Al–Si alloys, a uniform crystal orientation is obtained. In contrast, a random orientation can be detected in the hyper-eutectic Al–Si alloy (15% Si), which results from interruption of the growth of the α-Al dendrites due to precipitation of primary Si particles. There is no clear effect of crystal formation on ultimate tensile strength (UTS), whereas crystal orientation does influence the material ductility, with the alloys with a uniform crystal orientation being elongated beyond their UTS points and with necking occurring in the test specimens. In contrast, the alloys with a nonuniform crystal orientation are not elongated beyond their UTS points

The Au/Si eutectic bonding compatibility with KOH etching for 3D devices fabrication

Science.gov (United States)

Liang, Hengmao; Liu, Mifeng; Liu, Song; Xu, Dehui; Xiong, Bin

2018-01-01

KOH etching and Au/Si eutectic bonding are cost-efficient technologies for 3D device fabrication. Aimed at investigating the process compatibility of KOH etching and Au/Si bonding, KOH etching tests have been carried out for Au/bulk Si and Au/amorphous Si (a-Si) bonding wafers in this paper. For the Au/bulk Si bonding wafer, a serious underetch phenomenon occurring on the damage layer in KOH etching definitely results in packaging failure. In the microstructure analysis, it is found that the formation of the damage layer between the bonded layer and bulk Si is attributed to the destruction of crystal Si lattices in Au/bulk Si eutectic reaction. Considering the occurrence of underetch for Au/Si bonding must meet two requirements: the superfluous Si and the defective layer near the bonded layer, the Au/a-Si bonding by regulating the a-Si/Au thickness ratio is presented in this study. Only when the a-Si/Au thickness ratio is relatively low are there not underetch phenomena, of which the reason is the full reaction of the a-Si layer avoiding the formation of the damage layer for easy underetch. Obviously, the Au/a-Si bonding via choosing a moderate a-Si/Au thickness ratio (⩽1.5:1 is suggested) could be reliably compatible with KOH etching, which provides an available and low-cost approach for 3D device fabrication. More importantly, the theory of the damage layer proposed in this study can be naturally applied to relevant analyses on the eutectic reaction of other metals and single crystal materials.

Properties of subvisible cirrus clouds formed by homogeneous freezing

Directory of Open Access Journals (Sweden)

B. Kärcher

2002-01-01

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 (>10min clouds, capable of exerting a measurable radiative or chemical impact, are generated within a narrow range of updraft speeds below 1-2cm s-1 at temperatures below about 215K, with concentrations of ice crystals not exceeding 0.1cm-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. Two important conclusions emerge from this work. First, the above characteristics of SVCs may provide an explanation for why SVCs are more common in the cold tropical than in the warmer midlatitude tropopause region. Second, it seems likely that a limited number (-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.

Synthesis of a Novel Allyl-Functionalized Deep Eutectic Solvent to Promote Dissolution of Cellulose

Directory of Open Access Journals (Sweden)

Hongwei Ren

2016-08-01

Full Text Available Deep eutectic solvents (DESs offer attractive options for the “green” dissolution of cellulose. However, the protic hydroxyl group causes weak dissolving ability of DESs, requiring the substitution of hydroxyl groups in the cation. In this study, a novel allyl-functionalized DES was synthesized and characterized, and its possible effect on improved dissolution of cellulose was investigated. The DES was synthesized by a eutectic mixture of allyl triethyl ammonium chloride ([ATEAm]Cl and oxalic acid (Oxa at a molar ratio of 1:1 and a freezing point of 49 °C. The [ATEAm]Cl-Oxa exhibited high polarity (56.40 kcal/mol, dipolarity/polarizability effects (1.10, hydrogen-bond donating acidity (0.41, hydrogen-bond basicity (0.89, and low viscosity (76 cP at 120 °C owing to the π-π conjugative effect induced by the allyl group. The correlation between temperature and viscosity on the [ATEAm]Cl-Oxa fit the Arrhenius equation well. The [ATEAm]Cl-Oxa showed low pseudo activation energy for viscous flow (44.56 kJ/mol. The improved properties of the [ATEAm]Cl-Oxa noticeably promoted the solubility (6.48 wt.% of cellulose.

Characterization of age-hardening behavior of eutectic region in squeeze-cast A356-T5 alloy using nanoindenter and atomic force microscope

Energy Technology Data Exchange (ETDEWEB)

Youn, S.W. [Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564 (Japan)]. E-mail: youn.sung-won@aist.go.jp; Kang, C.G. [National Laboratory of Thixo/Rheo Forming, School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)]. E-mail: cgkang@pusan.ac.kr

2006-06-15

The nano/microstructure, the aging response (in T5 heat treatment), and the mechanical/tribological properties of the eutectic regions in squeeze-cast A356 alloy parts were investigated using nano/micro-indentation and mechanical scratching, combined with optical microscopy and atomic force microscope (AFM). Most eutectic Si crystals in the A356 alloy showed a modified morphology as fine-fibers. The loading curve for the eutectic region was more irregular than that of the primary Al region due to the presence of various particles of varying strength. In addition, the eutectic region showed lower pile-up and higher elastic recovery than the primary Al region. The aging responses of the eutectic regions in the squeeze-cast A356 alloys aged at 150 deg. C for different times (0, 2, 4, 8, 10, 16, 24, 36, and 72 h) were investigated. As the aging time increased, acicular Si particles in the eutectic regions gradually came to a fine structure. Both Vickers hardness (H {sub V}) and indentation (H {sub IT}) test results showed almost the same trend of aging curves, and the peak was obtained at the same aging time of 10 h. A remarkable size-dependence of the tests was found. The friction coefficient for the eutectic region was lower than that for the primary Al region.

Morphology of the aluminium-uranium eutectic

International Nuclear Information System (INIS)

Ambrozio Filho, F.; Vieira, R.R.

1976-01-01

The factors which might affect the eutectic structure including external condition during solidification as well as factors peculiar to each individual system is discussed. The structure of the Al-U eutectic, consisting of the solid solution of uranium in aluminium and UAl 4 , as obtained in ingot moulds and by unidirectional solidification. The extructure in terms of certain variables with emphasis on the growth characteristics of the phases comprising the eutectic the velocity of growth and thermal gradient in the liquid is also presented [pt

Photo- and radio-excited luminescence properties of Eu-doped La2O3–Al2O3 based eutectics

International Nuclear Information System (INIS)

Fujimoto, Yutaka; Kamada, Kei; Yanagida, Takayuki; Wakahara, Shingo; Suzuki, Shotaro; Kurosawa, Shunsuke; Yoshikawa, Akira

2013-01-01

Eutectic crystal of 0.5% Eu-doped 30LaAlO 3 –70Al 2 O 3 (vol %) was prepared by micro-pulling down (μ-PD) technique under nitrogen atmosphere. Being excited at a wavelength of 320 nm, the crystal exhibited intense emission band with a maximum at 450 nm which is corresponding to 4f 6 5d-4f 7 ( 8 S 7/2 ) transitions of Eu 2+ . The decay time and fluorescence quantum efficiency (QE) were determined to be about 475 ns and 60%, respectively. When alpha-ray excited the crystal, both Eu 2+ 4f 6 5d-4f 7 ( 8 S 7/2 ) and Eu 3+ 4f 6 -4f 6 ( 5 D 0 - 7 F 1,2 ) emission peaks were observed at 435 nm and 600 nm. By the pulse height spectra, the relative scintillation light yield of the crystal was about 4% compared with that of BGO commercial scintillator. -- Highlights: •0.5% Eu-doped 30LaAlO 3 –70Al 2 O 3 eutectic crystal was grown by μ-PD technique. •The crystal showed intense Eu 2+ 5d-4f emission at 450 nm under excited at 320 nm. •The fluorescence quantum efficiency was calculated to be about 60%. •The scintillation light yield was about 4% compared with that of BGO scintillator

Physical Aspects of Scraped Heat Exchanger Crystallizers : An Application in Eutectic Freeze Crystallization

NARCIS (Netherlands)

Rodriguez Pascual, M.

2009-01-01

One of the most important natural resources is fresh water. An unfortunate issue is however, the low availability and high demand of fresh water world-wide. From the total resources industry consumes about 20 % (1200 km3 yearly) [UN, 2007]. Industrial aqueous waste streams are therefore widely

Preparation and Thermal Properties of Eutectic Hydrate Salt Phase Change Thermal Energy Storage Material

Directory of Open Access Journals (Sweden)

Lin Liang

2018-01-01

Full Text Available In this study, a new cold storage phase change material eutectic hydrate salt (K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O was prepared, modified, and tested. The modification was performed by adding a nucleating agent and thickener. The physical properties such as viscosity, surface tension, cold storage characteristics, supercooling, and the stability during freeze-thaw cycles were studied. Results show that the use of nucleating agents, such as sodium tetraborate, sodium fluoride, and nanoparticles, are effective. The solidification temperature and latent heat of these materials which was added with 0, 3, and 5 wt% thickeners were −11.9, −10.6, and −14.8°C and 127.2, 118.6, 82.56 J/g, respectively. Adding a nucleating agent can effectively improve the nucleation rate and nucleation stability. Furthermore, increasing viscosity has a positive impact on the solidification rate, supercooling, and the stability during freeze-thaw cycles.

Influence of the freezing process on the pore structure of freeze-dried collagen sponges; Einfluss des Einfriervorganges auf die Porenstruktur gefriergetrockneter Kollagenschwaemme

Energy Technology Data Exchange (ETDEWEB)

Schoof, H.; Bruns, L.; Apel, J.; Heschel, I.; Rau, G. [Helmholz-Inst. fuer Biomedizinische Technik, Aachen (Germany)

1997-12-31

Freeze-dried sponges are used as colonisable tissue implants. As their porous structure is important for rapid colonisation it was found desirable to be able to produce homogeneous pore structures to specification. The structure of freeze-dried sponges is largely the same as the ice crystal morphology of frozen samples. In industrial manufacture suspensions are solidified in a cold bath. Freezing conditions are not stationary in this process, rendering ice crystal morphology inhomogeneous. However, studies on directed solidification as it is used in the Bridgman or the power-down method have shown that certain freezing conditions permit the production of collagen sponges of homogenous predefined pore size. [Deutsch] Gefriergetrocknete Kollagenschwaemme werden als besiedelbare Gewebeimplantate eingesetzt. Da die poroese Struktur fuer eine zuegige Besiedelung von grosser Bedeutung ist, sollen Kollagenschwaemme mit einer einstellbaren und homogenen Porenstruktur hergestellt werden. Die Struktur der gefriergetrockneten Schwaemme entspricht weitestgehend der Eiskristallmorphologie der gefrorenen Probe. Bei der industriellen Herstellung werden Suspensionen in einem Kaeltebad erstarrt. Die Einfrierbedingungen sind dabei nicht stationaer, was zu einer inhomogenen Eiskristallmorphologie fuehrt. Untersuchungen zur gerichteten Erstarrung nach dem Bridgman- und dem Power-Down-Verfahren ergaben jedoch, dass unter bestimmten Einfrierbedingungen Kollagenschwaemme mit homogener und definierbarer Porengroesse hergestellt werden koennen. (orig.)

Initial stages of solidification of eutectic alloys

International Nuclear Information System (INIS)

Lemaignan, Clement

1980-01-01

The study of the various initial stages of eutectic solidification - i.e. primary nucleation, eutectic structure formation and stable growth conditions - was undertaken with various techniques including low angle neutron diffusion, in-situ electron microscopy on solidifying alloys and classical metallography. The results obtained allow to discuss the effect of metastable states during primary nucleation, of surface dendrite during eutectic nucleation and also of the crystallographic anisotropy during growth. (author) [fr

Divorced eutectic in a HPDC magnesium-aluminum alloy

International Nuclear Information System (INIS)

Barbagallo, S.; Laukli, H.I.; Lohne, O.; Cerri, E.

2004-01-01

The morphology of the eutectic in a thin-wall high pressure die cast (HPDC) U-shape AM60 magnesium box was investigated by light microscope, SEM, TEM and EPMA. The extremely fast cooling rate taking place in the solidification process produces a highly segregated zone near the boundaries of small grains and a fine distribution of β particles, which is typical of a completely divorced eutectic. It was shown that the segregated zone is coherent with the primary α-Mg grain core even if the increased aluminium content produces a deformation of the hexagonal crystal lattice, which was estimated through diffraction patterns (SADP). The variation of the alloying elements content through the grain boundaries was shown by means of EPMA line scanning. The β particle composition was quantitatively investigated and the results show that, in comparison with the equilibrium phase diagram, the non-equilibrium phase boundary of the Mg 17 Al 12 region is moved some percent towards the lower aluminium content, at the high cooling rate that occurs in high pressure die castings. The cubic structure of the β phase was revealed by diffraction pattern. The presence of small Al-Mn particles both inside the grain and in the boundary region was also put in evidence by TEM

On the stable eutectic solidification of iron–carbon–silicon alloys

International Nuclear Information System (INIS)

Stefanescu, Doru M.; Alonso, Gorka; Larrañaga, Pello; Suarez, Ramon

2016-01-01

Extensive effort was expanded to elucidate the growth and morphology of the stable eutectic grains during early solidification of continuous cooled Fe–C–Si alloys. To this purpose, quenching experiments at successive stages during solidification have been carried out on five cast irons with various magnesium and titanium levels designed to produce graphite morphologies ranging from lamellar to mixed compacted–spheroidal. The graphite shape factors were measured on the metallographic samples, and their evolution as a function of the chemical composition and the solid fraction was analyzed. Extensive scanning electron microscopy was carried on to evaluate the change in graphite shape during early solidification, to establish the fraction of solid at which the transition from spheroidal-to-compacted-to-lamellar graphite occurs, and to outline the early morphology of the eutectic grains. It was confirmed that solidification of Mg containing irons started with the development of spheroidal graphite even at Mg levels as low as 0.013 mass%. Then, as solidification proceeds, when some spheroids developed one or more tails (tadpole graphite), the spheroidal-to-compacted graphite transition occurs. The new findings were then integrated in previous knowledge to produce an understanding of the eutectic solidification of these materials. It was concluded that in hypoeutectic lamellar graphite iron austenite/graphite eutectic grains can nucleate at the austenite/liquid interface or in the bulk of the liquid, depending on the sulfur content and on the cooling rate. When graphite nucleation occurs on the primary austenite, several eutectic grains can nucleate and grow on the same dendrite. The primary austenite continues growing as eutectic austenite and therefore the two have the same crystallographic orientation. Thus, a final austenite grain may include several eutectic grains. In eutectic irons the eutectic grains nucleate and grow mostly in the liquid. The eutectic

Pseudobinary eutectics in Cu–Ag–Ge alloy droplets under containerless condition

International Nuclear Information System (INIS)

Ruan, Y.; Wang, X.J.; Lu, X.Y.

2013-01-01

Highlights: ► Two pseudobinary eutectics form in Cu–Ag–Ge alloy. ► It is influenced by thermodynamic and kinetic factors of the alloy in the drop tube. ► As droplet size reduces, anomalous → lamellar → anomalous transition happens in (Ag + ζ). ► (Ag + ε 2 ) is a product of both peri-eutectic and pseudobinary eutectic transitions. -- Abstract: Pseudobinary eutectic generated by pseudobinary eutectic transition or peri-eutectic transition is a crucial structure in ternary alloy systems. Its formation mechanism strongly influences mechanical properties of these metallic materials. However, it was customarily neglected. In this paper, two pseudobinary eutectics, i.e. (Ag + ζ) and (Ag + ε 2 ), were investigated during the rapid solidification of Cu–Ag–Ge ternary alloy in a 3 m-drop tube. The sharp temperature variations and dramatic kinetic activities of the falling alloy droplets before solidification cause special microstructural characteristics. (Ag) dendrite is the heterogeneous nucleus for anomalous (Ag + ζ) pseudobinary eutectic in large droplets. Lamellar (Ag + ζ) pseudobinary eutectic grain forms independently on condition that primary (Ag) dendrite cannot form and its eutectic morphology becomes anomalous with the decrease of droplet size. Nanoscaled (Ag + ε 2 ) pseudobinary eutectic generating at the last stage of solidification is the product of both peri-eutectic and pseudobinary eutectic transitions. It distributes in the gaps of (Ag + ζ) pseudobinary eutectic grains and its morphology remains lamellar regardless of droplet size

The UC{sub 2−x} – Carbon eutectic: A laser heating study

Energy Technology Data Exchange (ETDEWEB)

Manara, D., E-mail: dario.manara@ec.europa.eu; Boboridis, K.; Morel, S.; De Bruycker, F.

2015-11-15

The UC{sub 2−x} – carbon eutectic has been studied by laser heating and fast multi-wavelength pyrometry under inert atmosphere. The study has been carried out on three compositions, two of which close to the phase boundary of the UC{sub 2−x} – C miscibility gap (with C/U atomic ratios 2 and 2.1), and one, more crucial, with a large excess of carbon (C/U = 2.82). The first two compositions were synthesised by arc-melting. This synthesis method could not be applied to the last composition, which was therefore completed directly by laser irradiation. The U – C – O composition of the samples was checked by using a combustion method in an ELTRA{sup ®} analyser. The eutectic temperature, established to be 2737 K ± 20 K, was used as a radiance reference together with the cubic – tetragonal (α → β) solid state transition, fixed at 2050 K ± 20 K. The normal spectral emissivity of the carbon-richer compounds increases up to 0.7, whereas the value 0.53 was established for pure hypostoichiometric uranium dicarbide at the limit of the eutectic region. This increase is analysed in the light of the demixing of excess carbon, and used for the determination of the liquidus temperature (3220 K ± 50 K for UC{sub 2.82}). Due to fast solid state diffusion, also fostered by the cubic – tetragonal transition, no obvious signs of a lamellar eutectic structure could be observed after quenching to room temperature. The eutectic surface C/UC{sub 2−x} composition could be qualitatively, but consistently, followed during the cooling process with the help of the recorded radiance spectra. Whereas the external liquid surface is almost entirely constituted by uranium dicarbide, it gets rapidly enriched in demixed carbon upon freezing. Demixed carbon seems to quickly migrate towards the inner bulk during further cooling. At the α → β transition, uranium dicarbide covers again the almost entire external surface. - Highlights: • The melting behaviour

Growth and Morphology of Rod Eutectics

Energy Technology Data Exchange (ETDEWEB)

Jing Teng; Shan Liu; R. Trivedi

2008-03-17

The formation of rod eutectic microstructure is investigated systematically in a succinonitrile-camphor alloy of eutectic composition by using the directional solidification technique. A new rod eutectic configuration is observed in which the rods form with elliptical cylindrical shape. Two different orientations of the ellipse are observed that differ by a 90{sup o} rotation such that the major and the minor axes are interchanged. Critical experiments in thin samples, where a single layer of rods forms, show that the spacing and orientation of the elliptic rods are governed by the growth rate and the sample thickness. In thicker samples, multi layers of rods form with circular cross-section and the scaling law between the spacing and velocity predicted by the Jackson and Hunt model is validated. A theoretical model is developed for a two-dimensional array of elliptical rods that are arranged in a hexagonal or a square array, and the results are shown to be consistent with the experimental observations. The model of elliptic rods is also shown to reduce to that for the circular rod eutectic when the lengths of the two axes are equal, and to the lamellar eutectic model when one of the axes is much larger than the other one.

Effect of Si and Co on the crystallization of Al-Ni-RE amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Wang, S.H. [Key Lab of Liquid structure and Heredity of Materials, Ministry of Education, South Campus of Shandong University, Jinan 250061 (China); Bian, X.F. [Key Lab of Liquid structure and Heredity of Materials, Ministry of Education, South Campus of Shandong University, Jinan 250061 (China)], E-mail: xfbian@sdu.edu.cn

2008-04-03

Crystallization of Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}, Al{sub 85}Ni{sub 10}Ce{sub 5}, Al{sub 87}Ni{sub 7}Nd{sub 6} and Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6} amorphous alloys has been studied by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The multiple transition metal (TM) (containing metalloid element) have significant effect on the crystallization behavior. A small addition of Si transforms a eutectic crystallization (Al{sub 85}Ni{sub 10}Ce{sub 5}) to a primary crystallization (Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}); while a small addition of Co transforms a primary crystallization (Al{sub 87}Ni{sub 7}Nd{sub 6}) to a eutectic crystallization (Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6}). In addition, the activation energies for crystallization (E{sub a}) are obtained to be 191, 290, 221 and 166 kJ/mol for the Al{sub 83}Ni{sub 10}Si{sub 2}Ce{sub 5}, Al{sub 85}Ni{sub 10}Ce{sub 5}, Al{sub 87}Ni{sub 5}Co{sub 2}Nd{sub 6} and Al{sub 87}Ni{sub 7}Nd{sub 6} amorphous alloys based on the Kissinger method, respectively. It is found that the primary crystallization of fcc-Al is characteristic of a lower E{sub a}, as compared with eutectic crystallization.

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.; Burlakov, V. M.; Ramos, Á . M.

2013-01-01

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.

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.

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

Thermal properties and thermal reliability of eutectic mixtures of some fatty acids as latent heat storage materials

International Nuclear Information System (INIS)

Sari, Ahmet; Sari, Hayati; Oenal, Adem

2004-01-01

The present study deals with two subjects. The first one is to determine the thermal properties of lauric acid (LA)-stearic acid (SA), myristic acid (MA)-palmitic acid (PA) and palmitic acid (PA)-stearic acid (SA) eutectic mixtures as latent heat storage material. The properties were measured by the differential scanning calorimetry (DSC) analysis technique. The second one is to study the thermal reliability of these materials in view of the change in their melting temperatures and latent heats of fusion with respect to repeated thermal cycles. For this aim, the eutectic mixtures were subjected to 360 repeated melt/freeze cycles, and their thermal properties were measured after 0, 90,180 and 360 thermal cycles by the technique of DSC analysis. The DSC thermal analysis results show that the binary systems of LA-SA in the ratio of 75.5:24.5 wt.%, MA-PA in the ratio of 58:42 wt.% and PA-SA in the ratio of 64.2:35.8 wt.% form eutectic mixtures with melting temperatures of 37.0, 42.60 and 52.30 deg. C and with latent heats of fusion of 182.7, 169.7 and 181.7 J g -1 , respectively. These thermal properties make them possible for heat storage in passive solar heating applications with respect to climate conditions. The accelerated thermal cycle tests indicate that the changes in the melting temperatures and latent heats of fusion of the studied eutectic mixtures are not regular with increasing number of thermal cycles. However, these materials, latent heat energy storage materials, have good thermal reliability in terms of the change in their thermal properties with respect to thermal cycling for about a one year utility period

Structure of the aluminium-uranium eutectic

International Nuclear Information System (INIS)

Ambrozio Filho, F.; Vieira, R.R.

1975-01-01

The authors discuss the factors which might effect the eutectic structure, including external conditions during solidification as well as factors peculiar to each individual system. They studied the structure of the A1-U eutectic, consisting of the solid solution of uranium in aluminium and UA1 4 , as obtained in ingot moulds and by unidirectional solidification, and found a tendency for the structure to develop in a spiral, in the form of a rhombus. They discuss this structure in terms of certain variables with emphasis on the growth characteristics of the phases comprising the eutectic, the velocity of growth and thermal gradient in the liquid [pt

Mechanical properties of thermomechanical treated hyper-eutectic Al-Si-(Fe, Mn, Cu) materials

OpenAIRE

Umezawa, Osamu

2005-01-01

Tensile and high-cycle fatigue behavior of thermomechanical treated hyper-eutectic Al-Si-(Fe, Mn, Cu) materials were studied. Through the repeated thermomechanical treatment (RTMT) which is a repeat of the multi steps cold-working followed by heat treatment, Si crystals and/or intermetallic compounds were broken into some fragments and dispersed in the aluminum matrix. Fine dispersion of the second phase particles exhibited good ductility, since early fracture was overcome. A few large Si cry...

Mechanism of eutectic formation upon compaction and its effects on tablet properties

International Nuclear Information System (INIS)

Bi, Mingda; Hwang, Sung-Joo; Morris, Kenneth R.

2003-01-01

The unique property of a eutectic mixture is a lower melting temperature than that of any of its pure components. What differentiates a eutectic mixture from a simple physical mixture is less well understood. This impedes the ability to anticipate and/or detect unintentional eutectic formation during pharmaceutical tablet manufacturing and any potential negative impact. In this study, a thermodynamic/heat transfer approach was used to explain the mechanism of eutectic formation upon exposure to a physical stress, i.e. compaction, and a differential scanning calorimetric (DSC) method was developed to detect and quantify the amount of eutectic formed in the compacts. Furthermore, the mechanism of eutectic formation upon compaction was tested experimentally by correlating the amount of eutectic formed in tablets with the particle size, compaction force, the estimated intimate contact area between the eutectic-forming materials, calculated tablet tensile strength, and tablet porosity. The effect of the presence of eutectics on tablet properties was also investigated. The results show that intimate contact and mutual solubility between eutectic-forming materials are the necessary and sufficient criteria for eutectic formation upon compaction. The systems of acetaminophen (APAP)/caffeine and APAP/propylphenazone were both shown to exhibit eutectic behavior upon compaction and the extent of formation was dependent upon the amount of intimate contact between eutectic-forming materials. Finally, it was found that eutectic had no negative effect on tablet hardness

A pore-scale study of fracture dynamics in rock using X-ray micro-CT under ambient freeze-thaw cycling.

Science.gov (United States)

De Kock, Tim; Boone, Marijn A; De Schryver, Thomas; Van Stappen, Jeroen; Derluyn, Hannelore; Masschaele, Bert; De Schutter, Geert; Cnudde, Veerle

2015-03-03

Freeze-thaw cycling stresses many environments which include porous media such as soil, rock and concrete. Climate change can expose new regions and subject others to a changing freeze-thaw frequency. Therefore, understanding and predicting the effect of freeze-thaw cycles is important in environmental science, the built environment and cultural heritage preservation. In this paper, we explore the possibilities of state-of-the-art micro-CT in studying the pore scale dynamics related to freezing and thawing. The experiments show the development of a fracture network in a porous limestone when cooling to -9.7 °C, at which an exothermal temperature peak is a proxy for ice crystallization. The dynamics of the fracture network are visualized with a time frame of 80 s. Theoretical assumptions predict that crystallization in these experiments occurs in pores of 6-20.1 nm under transient conditions. Here, the crystallization-induced stress exceeds rock strength when the local crystal fraction in the pores is 4.3%. The location of fractures is strongly related to preferential water uptake paths and rock texture, which are visually identified. Laboratory, continuous X-ray micro-CT scanning opens new perspectives for the pore-scale study of ice crystallization in porous media as well as for environmental processes related to freeze-thaw fracturing.

Characterization of age-hardening behavior of eutectic surface on rheo-cast A356-T5 alloy by using nano/micro-indentation, scratching and atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Youn, S.W. [Department of Precision and Mechanical Engineering, Pusan National University, Pusan 609-735 (Korea, Republic of)]. E-mail: youn.sung-won@aist.go.jp; Kang, C.G. [National Research Laboratory of Thixo/Rheo Forming, School of Mechanical Engineering, Pusan National University, JangJun-Dong, Gumjung-Gu, Pusan 609-735 (Korea, Republic of)]. E-mail: cgkang@pusan.ac.kr

2006-11-10

This study investigates the nano/microstructure, the aging response (in T5 heat treatment), and the mechanical/tribological properties of the eutectic regions in rheo-cast A356 alloy parts using nano/micro-indentation and mechanical scratching, combined with optical microscopy and atomic force microscope (AFM). Most eutectic Si crystals in the A356 alloy showed a modified morphology as fine-fibers. The loading curve for the eutectic region was more irregular than that of the primary Al region due to the presence of various particles of varying strength. The aging responses of the eutectic regions in the rheo-cast A356 alloys aged at 150 deg. C for different times (0, 2, 4, 8, 10, 16, 24, 36, and 72 h) were investigated. Both Vickers hardness and indentation test results showed a similar trend of aging curves, and the peak was obtained at the same aging time of 10 h. A remarkable size-dependence of the tests was found. The friction coefficient for the eutectic region was lower than that for the primary Al region.

Freeze-Casting Produces a Graphene Oxide Aerogel with a Radial and Centrosymmetric Structure.

Science.gov (United States)

Wang, Chunhui; Chen, Xiong; Wang, Bin; Huang, Ming; Wang, Bo; Jiang, Yi; Ruoff, Rodney S

2018-05-14

We report the assembly of graphene oxide (G-O) building blocks into a vertical and radially aligned structure by a bidirectional freeze-casting approach. The crystallization of water to ice assembles the G-O sheets into a structure, a G-O aerogel whose local structure mimics turbine blades. The centimeter-scale radiating structure in this aerogel has many channels whose width increases with distance from the center. This was achieved by controlling the formation of the ice crystals in the aqueous G-O dispersion that grew radially in the shape of lamellae during freezing. Because the shape and size of ice crystals is influenced by the G-O sheets, different additives (ethanol, cellulose nanofibers, and chitosan) that can form hydrogen bonds with H 2 O were tested and found to affect the interaction between the G-O and formation of ice crystals, producing ice crystals with different shapes. A G-O/chitosan aerogel with a spiral pattern was also obtained. After chemical reduction of G-O, our aerogel exhibited elasticity and absorption capacity superior to that of graphene aerogels with "traditional" pore structures made by conventional freeze-casting. This methodology can be expanded to many other configurations and should widen the use of G-O (and reduced G-O and "graphenic") aerogels.

Structural models of faceted-faceted eutectic system vanillin-acenaphthene

International Nuclear Information System (INIS)

Sharma, B.L.

2003-01-01

Thermodynamic model for the eutectic system vanillin-acenaphthene has been developed by analysing the excess functions computed from its experimentally determined solidus-liquidus equilibrium data. Spontaneous nucleation model has been explored from the maximum limit of undercooling of the system and verified by the experimental evidences of dislocation mechanism governing the anisotropic velocity of crystallisation determined at different undercoolings. Viscosity measurements of eutectic and non-eutectic melts at different temperatures revealed the essence of peculiar structural changes and specific energy interactions in the eutectic melt in the temperature range near its melting temperature. The rheological activation energy, E vis for eutectic and non-eutectic melts is found to be a function of temperature. Crystalline faceted structure of the system has been furnished with morphological evidences obtained from microscopic studies at different growth rates, whereas whisker reinforced structural model has been accomplished with mechanical properties computed for both isotropic and anisotropic modes of growth. Of greater interest is the special reference of moderate anisotropic growth, since experimental confirmation was obtained for the theoretical shape of parabolic variation in the mechanical properties of eutectic composite material with growth velocity. Direct evidence of three- to four-fold increase in strength properties of the eutectic material at its moderate anisotropic growth velocity (3.11x10 -7 m 3 s -1 ) in comparison with its isotropic growth in an ice bath (∼273 K), confirms a complete composite microstructure with whiskers in equilibrium with the matrix, embedded parallel to the growth direction

Changes in Ultrastructure and Sensory Characteristics on Electro-magnetic and Air Blast Freezing of Beef during Frozen Storage

Science.gov (United States)

2015-01-01

The ultrastructure in the beef muscle of the electro-magnetic resonance and air blast freezing during the frozen storage, and the changes in the quality characteristics after thawing were evaluated. The size of ice crystal was small and evenly formed in the initial freezing period, and it showed that the size was increased as the storage period was elapsed (pfreezing showed the size of ice crystal with a lower rate of increase than the air blast freezing during the frozen storage. The thawing loss of beef stored by the electro-magnetic resonance freezing was significantly lower than the air blast freezing during frozen storage (pfreezing was higher than the air blast on 8 month (pfreezing did not show the difference until 4 months, and it showed higher acceptability in comparison with the beef stored by the air blast freezing. Thus, it is considered that the freezing method has an effect on the change in the ultrastructure and quality characteristics of the beef. PMID:26761797

Nanocrystals-based Macroporous Materials Synthesized by Freeze-drying Combustion

International Nuclear Information System (INIS)

Yan, Ruiqiang; Chen, Yu; Lin, Ye; Chen, Fanglin

2016-01-01

We present a novel freeze-drying combustion method for synthesis of macroporous powders with nano-network, using Sm 0.2 Ce 0.8 O 1.9 (SDC) as an example. The metal nitrate salt solution mixed with glycine is frozen to form homogeneous nitrate/glycine mixture and then freeze-dried through sublimation of ice crystals. Upon combustion of the freeze-dried mixture, SDC powders with macroporous microstructure consisting of 10–20 nm nanocrystals, high surface area and excellent sinterability are achieved. High resolution transmission electron microscopy (HRTEM) analysis indicates that nanodomains due to aggregation/segregation of dopants in the SDC powders obtained from freeze-drying combustion are much smaller than those in the SDC powders synthesized by the conventional nitrate solution combustion approach, demonstrating better elemental homogeneity and improved conductivity. Using low cost precursors and simple processing conditions, freeze-drying combustion can be a versatile method to synthesize nanocrystalline powders with excellent composition homogeneity for broad applications.

Electrochemically shape-controlled synthesis in deep eutectic solvents of Pt nanoflowers with enhanced activity for ethanol oxidation

International Nuclear Information System (INIS)

Wei Lu; Fan Youjun; Wang Honghui; Tian Na; Zhou Zhiyou; Sun Shigang

2012-01-01

Highlights: ► The electrochemically shape-controlled synthesis in deep eutectic solvents (DESs) has been applied to produce the uniform Pt nanoflowers with sharp single crystal petals and high density of atomic steps. ► The as-prepared Pt nanoflowers exhibit higher electrocatalytic activity and stability than commercial Pt black catalyst toward ethanol electrooxidation. ► The growth of Pt nanoflowers in DESs by the simple electrochemical route is straightforward and controllable in terms of nanoflowers’ shape and size. - Abstract: The electrochemically shape-controlled synthesis in deep eutectic solvents (DESs) has been applied to produce the electrocatalyst of Pt nanoflowers. The uniform Pt nanoflowers with sharp single crystal petals and high density of atomic steps were characterized by SEM, TEM, XRD, XPS and electrochemical tests. The results illustrated that the as-prepared Pt nanoflowers exhibit higher electrocatalytic activity and stability than commercial Pt black catalyst toward ethanol electrooxidation. The growth of Pt nanoflowers in DESs by the simple electrochemical route is straightforward and controllable in terms of nanoflowers’ shape and size, which can be applied in shape-controlled synthesis of other noble metal nanoparticles with high catalytic activity.

Control of the structural parameters in the (Zn – Zn16Ti single crystal growth

Directory of Open Access Journals (Sweden)

W. Wołczyński

2011-10-01

Full Text Available The (Zn - single crystal was obtained by means of the Bridgman system. Several growth rates were applied during the experiment. The graphite crucible was used in order to perform the solidification process. The unidirectional solidification occurred with the presence of the moving temperature field. The thermal gradient was positive so that the constrained growth of the single crystal was ensured. The (Zn single crystal was doped with small addition of titanium and copper. The titanium formed an intermetallic compound Zn16-Ti. The copper was solved in the solid solution (Zn. The precipitates of (Zn and Zn16-Ti formed a stripes localized cyclically along the single crystal length. The intermetallic compound Zn16-Ti strengthened the (Zn single crystal. The structural transitions were observed in the stripes with the increasing solidification rate. Within the first range of the solidification rates ( the irregular L-shape rod-like intermetalliccompoundwas revealed. At the- threshold growth rate branches disappear continuously till the growth rate equal to. At the same range of growth rates the regular lamellar eutectic structure (Zn – Zn16-Ti appeared continuously and it existed exclusively till the second threshold growth rate equal to. Above the second threshold growth rate the regular rod-like eutectic structure was formed, only. Thegeneral theory for the stationary eutectic solidification was developed. According to this theory the eutectic structure localized within the stripes is formed under stationary state. Therefore, the criterion of the minimum entropy production defines well the stationary solidification. The entropy production was calculated for the regular rod-like eutectic structure formation and for the regular lamellar eutectic structure formation. It was postulated that the observed structure are subjected to the competition. That is why the structural transitionwere observed at therevealedthreshold growth rates.Moreover, it was

Shape of growing crystals of primary phases in autectic alloys of Fe - Fe2B and Ni - Ni3B systems

International Nuclear Information System (INIS)

Tavadze, F.N.; Garibashvili, V.I.; Nakaidze, Sh.G.

1983-01-01

Shapes of Fe 2 B and Ni 3 B crystal growth in eutectic Fe-B and Ni-B system alloys are considered. Iron hemiboride primary crystals take the form of a plane-face phase boundary and inherit a tetragonal prismatic lattice. After the crystal attains the critical size the dendritic branching occurs resulting in formation of a typical sceleton dendrite. Comparison of data obtained with entropy of melting for Fe 2 B and Ni 3 B borides shows that FeB crystals during the growth should take the spherical form. It is stated that the shape of growing crystals in Fe-Fe 2 B and Ni-Ni 2 B eutectic colonies is determined by the shape of borides

Effects of high pressure freezing (HPF) on denaturation of natural actomyosin extracted from prawn (Metapenaeus ensis).

Science.gov (United States)

Cheng, Lina; Sun, Da-Wen; Zhu, Zhiwei; Zhang, Zhihang

2017-08-15

Effects of protein denaturation caused by high pressure freezing, involving Pressure-Factors (pressure, time) and Freezing-Factors (temperature, phase transition, recrystallization, ice crystal types), are complicated. In the current study, the conformation and functional changes of natural actomyosin (NAM) under pressure assisted freezing (PAF, 100,150,300,400,500MPa P -20°C/25min ), pressure shift freezing (PSF, 200MPa P -20°C/25min ), and immersion freezing ( 0.1MPa P -20°C/5min ) after pressure was released to 0.1MPa, as compared to normal immersion freezing process (IF, 0.1MPa P -20°C/30min ). Results indicated that PSF ( 200MPa P -20°C/30min ) could reduce the denaturation of frozen NAM and a pressure of 300MPa was the critical point to induce such a denaturation. During the periods of B→D in PSF or B→C→D in PAF, the generation and growth of ice crystals played an important role on changing the secondary and tertiary structure of the treated NAM. Copyright © 2017 Elsevier Ltd. All rights reserved.

Catalytic Gasification of Coal using Eutectic Salt Mixtures

Energy Technology Data Exchange (ETDEWEB)

Atul Sheth; Pradeep Agrawal; Yaw D. Yeboah

1998-12-04

The objectives of this study are to: identify appropriate eutectic salt mixture catalysts for coal gasification; assess agglomeration tendency of catalyzed coal; evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; evaluate the recovery, regeneration and recycle of the spent catalysts; and conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process. A review of the collected literature was carried out. The catalysts which have been used for gasification can be roughly classified under the following five groups: alkali metal salts; alkaline earth metal oxides and salts; mineral substances or ash in coal; transition metals and their oxides and salts; and eutectic salt mixtures. Studies involving the use of gasification catalysts have been conducted. However, most of the studies focused on the application of individual catalysts. Only two publications have reported the study of gasification of coal char in CO2 and steam catalyzed by eutectic salt mixture catalysts. By using the eutectic mixtures of salts that show good activity as individual compounds, the gasification temperature can be reduced possibly with still better activity and gasification rates due to improved dispersion of the molten catalyst on the coal particles. For similar metal/carbon atomic ratios, eutectic catalysts were found to be consistently more active than their respective single salts. But the exact roles that the eutectic salt mixtures play in these are not well understood and details of the mechanisms remain unclear. The effects of the surface property of coals and the application methods of eutectic salt mixture catalysts with coal chars on the reactivity of gasification will be studied. Based on our preliminary evaluation of the literature, a ternary

Dispersion Stability of O/W Emulsions with Different Oil Contents Under Various Freezing and Thawing Conditions.

Science.gov (United States)

Katsuki, Kazutaka; Miyagawa, Yayoi; Nakagawa, Kyuya; Adachi, Shuji

2017-07-01

Freezing and thawing of oil-in-water (O/W) emulsion-type foods bring about oil-water separation and deterioration; hence, the effects of freezing and thawing conditions on the destabilization of O/W emulsions were examined. The freezing rate and thawing temperature hardly affected the stability of the O/W emulsion. O/W emulsions having different oil fractions were stored at temperatures ranging from -30 to -20 °C and then thawed. The stability after thawing depended on the storage temperature, irrespective of the oil fraction of the emulsion. A good correlation was found between the time at which the stability began to decrease and the time taken for the oil to crystalize. These results indicated that the dominant cause for the destabilization of the O/W emulsion during freezing and thawing is the crystallization of the oil phase and that the effects of the freezing and thawing rates on the stability are insignificant. © 2017 Institute of Food Technologists®.

Eutectic growth under acoustic levitation conditions.

Science.gov (United States)

Xie, W J; Cao, C D; Lü, Y J; Wei, B

2002-12-01

Samples of Pb-Sn eutectic alloy with a high density of 8.5 x 10(3) kg/m(3) are levitated with a single-axis acoustic levitator, and containerlessly melted and then solidified in argon atmosphere. High undercoolings up to 38 K are obtained, which results in a microstructural transition of "lamellas-broken lamellas-dendrites." This transition is further investigated in the light of the coupled zone for eutectic growth and the effects of ultrasound. The breaking of regular eutectic lamellas and suppression of gravity-induced macrosegregation of (Pb) and (Sn) dendrites are explained by the complicated internal flow inside the levitated drop, which is jointly induced by the shape oscillation, bulk vibration and rotation of the levitated drop. The ultrasonic field is also found to drive forced surface vibration, which subsequently excites capillary ripples and catalyzes nucleation on the sample surface.

Eutectic Al-Si-Cu-Fe-Mn alloys with enhanced mechanical properties at room and elevated temperature

International Nuclear Information System (INIS)

Wang, E.R.; Hui, X.D.; Chen, G.L.

2011-01-01

Highlights: → Fabricated a kind of high performance Al-Si alloy with low production costs. → Clarified two different morphologies of α-Fe and corresponding crystal structures. → Analyzed the crystallography of Cu-rich phases before and after T6 treatment. → Fracture mechanism of precipitates in experimental alloys during tensile process. -- Abstract: In this paper, we report a novel kind of eutectic Al-Si-Cu-Fe-Mn alloy with ultimate tensile strength up to 336 MPa and 144.3 MPa at room temperature and 300 o C, respectively. This kind of alloy was prepared by metal mold casting followed by T6 treatment. The microstructure is composed of eutectic and primary Si, α-Fe, Al 2 Cu and α-Al phases. Iron-rich phases, which were identified as BCC type of α-Fe (Al 15 (Fe,Mn) 3 Si 2 ), exist in blocky and dendrite forms. Tiny blocky Al 2 Cu crystals disperse in α-Fe dendrites or at the grain boundaries of α-Al. During T6 treatment, Cu atoms aggregate from the super-saturation solid solution to form GP zones, θ'' or θ'. Further analysis found that the enhanced mechanical properties of the experimental alloy are mainly attributed to the formation of α-Fe and copper-rich phases.

Numerical Simulation of the Freeze-Thaw Behavior of Mortar Containing Deicing Salt Solution.

Science.gov (United States)

Esmaeeli, Hadi S; Farnam, Yaghoob; Bentz, Dale P; Zavattieri, Pablo D; Weiss, Jason

2017-02-01

This paper presents a one-dimensional finite difference model that is developed to describe the freeze-thaw behavior of an air-entrained mortar containing deicing salt solution. A phenomenological model is used to predict the temperature and the heat flow for mortar specimens during cooling and heating. Phase transformations associated with the freezing/melting of water/ice or transition of the eutectic solution from liquid to solid are included in this phenomenological model. The lever rule is used to calculate the quantity of solution that undergoes the phase transformation, thereby simulating the energy released/absorbed during phase transformation. Undercooling and pore size effects are considered in the numerical model. To investigate the effect of pore size distribution, this distribution is considered using the Gibbs-Thomson equation in a saturated mortar specimen. For an air-entrained mortar, the impact of considering pore size (and curvature) on freezing was relatively insignificant; however the impact of pore size is much more significant during melting. The fluid inside pores smaller than 5 nm (i.e., gel pores) has a relatively small contribution in the macroscopic freeze-thaw behavior of mortar specimens within the temperature range used in this study (i.e., +24 °C to -35 °C), and can therefore be neglected for the macroscopic freeze-thaw simulations. A heat sink term is utilized to simulate the heat dissipation during phase transformations. Data from experiments performed using a low-temperature longitudinal guarded comparative calorimeter (LGCC) on mortar specimens fully saturated with various concentration NaCl solutions or partially saturated with water is compared to the numerical results and a promising agreement is generally obtained.

Recent developments in novel freezing and thawing technologies applied to foods.

Science.gov (United States)

Wu, Xiao-Fei; Zhang, Min; Adhikari, Benu; Sun, Jincai

2017-11-22

This article reviews the recent developments in novel freezing and thawing technologies applied to foods. These novel technologies improve the quality of frozen and thawed foods and are energy efficient. The novel technologies applied to freezing include pulsed electric field pre-treatment, ultra-low temperature, ultra-rapid freezing, ultra-high pressure and ultrasound. The novel technologies applied to thawing include ultra-high pressure, ultrasound, high voltage electrostatic field (HVEF), and radio frequency. Ultra-low temperature and ultra-rapid freezing promote the formation and uniform distribution of small ice crystals throughout frozen foods. Ultra-high pressure and ultrasound assisted freezing are non-thermal methods and shorten the freezing time and improve product quality. Ultra-high pressure and HVEF thawing generate high heat transfer rates and accelerate the thawing process. Ultrasound and radio frequency thawing can facilitate thawing process by volumetrically generating heat within frozen foods. It is anticipated that these novel technologies will be increasingly used in food industries in the future.

Formation of anomalous eutectic in Ni-Sn alloy by laser cladding

Science.gov (United States)

Wang, Zhitai; Lin, Xin; Cao, Yongqing; Liu, Fencheng; Huang, Weidong

2018-02-01

Ni-Sn anomalous eutectic is obtained by single track laser cladding with the scanning velocity from 1 mm/s to 10 mm/s using the Ni-32.5 wt.%Sn eutectic powders. The microstructure of the cladding layer and the grain orientations of anomalous eutectic were investigated. It is found that the microstructure is transformed from primary α-Ni dendrites and the interdendritic (α-Ni + Ni3Sn) eutectic at the bottom of the cladding layer to α-Ni and β-Ni3Sn anomalous eutectic at the top of the cladding layer, whether for single layer or multilayer laser cladding. The EBSD maps and pole figures indicate that the spatially structure of α-Ni phase is discontinuous and the Ni3Sn phase is continuous in anomalous eutectic. The transformation from epitaxial growth columnar at bottom of cladding layer to free nucleation equiaxed at the top occurs, i.e., the columnar to equiaxed transition (CET) at the top of cladding layer during laser cladding processing leads to the generation of anomalous eutectic.

Eutectics Me5Si3-MeSi2 in a triple system Mo-W-Si

International Nuclear Information System (INIS)

Gnesin, B.A.; Gurjiyants, P.A.; Borisenko, E.B.

2001-01-01

Refractory metals silicides high-melting point eutectics are of great interest for different high temperature applications: production of composite materials with silicon carbide skeleton, antioxidant protective coatings on carbon materials, brazing of carbon, silicon carbide and refractory metals alloys materials. Phase diagrams Mo-Si and W-Si are compared: diagrams are similar but not in all significant details. Number of possible crystal structures for molybdenum silicides is at least twice more, than for tungsten and this difference is manifested distinctly for composite samples with different W-Mo ratio air high-temperature tests. In tests of new silicon carbide-refractory metal silicides composites materials (REFSIC) with 10-20 seconds heating time up to 1700 o C and 20-40 seconds time of cooling silicides with molybdenum prevalence were not so steady as tungsten based silicides. Experimental data concerning eutectic temperature dependence on W-Mo ratio, X-ray diffraction data, scanning electron and optical microscopy structure investigations results and some properties are discussed. (author)

The novel eutectic microstructures of Si-Mn-P ternary alloy

International Nuclear Information System (INIS)

Wu Yaping; Liu Xiangfa

2010-01-01

The microstructures of Si-Mn-P alloy manufactured by the technique of combining phosphorus transportation and alloy melting were investigated using electron probe micro-analyzer (EPMA). The phase compositions were determined by energy spectrum and the varieties of eutectic morphologies were discussed. It is found that there is no ternary compound but Si, MnP and MnSi 1.75-x could appear when the Si-Mn-P alloy's composition is proper. Microstructure is greatly refined by rapid solidification technique and the amount of eutectic phases change with faster cooling rates. Moreover, primary Si or MnP are surrounded firstly by the binary eutectic (Si + MnP) and then the ternary eutectic (Si + MnSi 1.75-x + MnP) which also exhibit binary structures due to divorced eutectic determined by the particularity of some Si-Mn-P alloys.

Influence of Lanthanum on Solidification, Microstructure, and Mechanical Properties of Eutectic Al-Si Piston Alloy

Science.gov (United States)

Ahmad, R.; Asmael, M. B. A.

2016-07-01

The effects of Lanthanum (La) concentration on the solidification parameters of the α-Al, Al-Si, and Al-Cu phases and on the microstructure, tensile, and hardness properties of eutectic Al-Si-Cu-Mg alloy were systematically investigated. The solidification parameters were examined using computer-aided cooling curve thermal analysis (CA-CCTA). The cooling curve and microstructure analysis showed that La altered the Si structure. The nucleation and growth temperatures of eutectic Si decreased when 0.3 wt.% La was added, and a high depression temperature was obtained with 1.0 wt.% La. High amounts of La considerably modified the Si structure and decreased the area and aspect ratio by 69.9 and 51%, respectively. The thermal analysis result recorded a faster freezing time with the La addition and a 36% alteration in the secondary dendrite arm spacing. Two secondary or ternary La-rich intermetallic phases were formed with needle- and plate-like structures. Furthermore, the mechanical properties were investigated by hardness and tensile tests with different La concentrations. The addition of small amounts of La (0.1 wt.%) significantly improved the ultimate tensile strength and quality index of the Al-Si-Cu-Mg alloy. In addition, the hardness value of Al-11Si-Cu increased by 7-8% with the increasing amount of La added.

Preparation, morphology and thermal properties of electrospun fatty acid eutectics/polyethylene terephthalate form-stable phase change ultrafine composite fibers for thermal energy storage

International Nuclear Information System (INIS)

Cai Yibing; Ke Huizhen; Lin Liang; Fei Xiuzhu; Wei Qufu; Song Lei; Hu Yuan; Fong Hao

2012-01-01

suggested that the heat enthalpies of melting and crystallization of the ultrafine composite fibers increased gradually with increasing fatty acid eutectics amounts, but their phase transition temperatures had almost no obvious variation as relative to the corresponding fatty acid eutectics. Meanwhile, the characteristic temperatures and heat enthalpies of the ultrafine composite fibers varied with the different types of binary fatty acid eutectics. TGA results indicated that the degradation of electrospun binary fatty acid eutectics/PET ultrafine composite fibers with representative mass ratio of 100/100 had two steps and corresponded respectively to the degradations of binary fatty acid eutectics and PET polymer chains; and the charred residue at 700 °C of the composite fibers was lower than that of the neat PET fibers. It could be envisioned that the electrospun binary fatty acid eutectics/PET composite fibers would be extensively used for latent heat storage in the field of building energy conservation.

Structure of eutectic alloys of Au with Si and Ge

Energy Technology Data Exchange (ETDEWEB)

Takeda, S. [Faculty of Sciences, Kyushu University, 4-2-1, Ropponmatsu, Fukuoka 810-8560 (Japan)], E-mail: takeda@rc.kyushu-u.ac.jp; Fujii, H. [Graduate School of Sciences, Kyushu University, 4-2-1, Ropponmatsu, Fukuoka 810-8560 (Japan); Kawakita, Y. [Faculty of Sciences, Kyushu University, 4-2-1, Ropponmatsu, Fukuoka 810-8560 (Japan); Tahara, S.; Nakashima, S. [Graduate School of Sciences, Kyushu University, 4-2-1, Ropponmatsu, Fukuoka 810-8560 (Japan); Kohara, S.; Itou, M. [Japan Synchrotron Radiation Research Institute, 1-1-1 Koto Sayo-cho, Sayo Hyogo 679-5198 (Japan)

2008-03-06

Au-Si and Au-Ge alloy systems have a deep eutectic point in the Au-rich concentration region where the melting point falls down to 633 K. In order to investigate the liquid structure in relation to the glass-forming tendency of these alloys, high-energy X-ray diffraction measurements have been carried out at the eutectic composition and at compositions with excess amounts of Au or IVb element. The nearest neighbor correlations in the eutectic liquids are intense and sharp in the pair distribution function and exhibit a rather small temperature dependence in comparison with those alloys of other than the eutectic composition. Structural models for these liquid alloys are proposed with the aid of reverse Monte Carlo simulation. The reproduced atomic arrangements around the eutectic region exhibit a substitutional-type structure where the dense random packing of Au atoms is preserved and Si or Ge atoms occupy the Au-sites at random.

The creep behavior of In-Ag eutectic solder joints

International Nuclear Information System (INIS)

Reynolds, H.L.; Kang, S.H.; Morris, J.W. Jr.; Univ. of California, Berkeley, CA

1999-01-01

The addition of 3 wt.% Ag to In results in a eutectic composition with improved mechanical properties while only slightly lowering the melting temperature. Steady-state creep properties of In-Ag eutectic solder joints have been measured using constant load tests at 0, 30, 60, and 90 C. Constitutive equations are derived to describe the creep behavior. The data are well represented by an equation of the form proposed by Dorn: a power-law equation applies to each independent creep mechanism. Two parallel mechanisms were observed for the In-Ag eutectic joints. The high-stress mechanism is a bulk mechanism with a thermal dependence dominated by the thermal dependence of creep in the In-rich matrix. The low-stress mechanism is a grain boundary mechanism. Results of this work are discussed with regard to creep behavior of typical eutectic systems

Study on corrosion test techniques in lead bismuth eutectic flow. Joint research report in JFY2002

International Nuclear Information System (INIS)

Takahashi, Minoru; Sekimoto, Hiroshi

2003-03-01

The evaluation of corrosion behaviors of core and structural materials in lead bismuth eutectic is one of the key issues for the utilization of lead bismuth eutectic as a coolant of the primary loops of lead bismuth cooled fast breeder reactors (FBRs) and the intermediate heat transport media of new-type steam generators of the sodium cooled FBRs. The purpose of the present study is to establish corrosion test techniques in lead bismuth eutectic flow. The techniques of steel corrosion test and oxygen control in flowing lead bismuth eutectic, and the technologies of a lead bismuth flow test at high temperature and high velocity were developed through corrosion test using a lead bismuth flow test loop of the Tokyo Institute of Technology in JFY2002. The major results are summarized as follows: (1) Techniques of fabrication, mount and rinse of corrosion specimens, measurement method of weight loss, and SEM/EDX analysis method have been established through lead bismuth corrosion test. (2) Weight losses were measured, corrosion and lead bismuth-adhered layers and eroded parts were observed in two 1000 hr-corrosion tests, and the results were compared with each other for twelve existing steels including ODS, F82H and SUH-3. (3) An oxygen sensor made of zirconia electrolyte structurally resistant to thermal stress and thermal shock was developed and tested in the lead bismuth flow loop. Good performance has been obtained. (4) An oxygen control method by injecting argon and hydrogen mixture gas containing steam into lead bismuth was applied to the lead bismuth flow loop, and technical issues for the development of the oxygen control method were extracted. (5) Technical measures for freezing and leakage of lead bismuth in the flow loop were accumulated. (6) Technical measures for flow rate decrease/blockage due to precipitation of oxide and corrosion products in a low temperature section of the lead bismuth flow loop were accumulated. (7) Electromagnetic flow meters with MI

Monotonic and fatigue deformation of Ni--W directionally solidified eutectic

International Nuclear Information System (INIS)

Garmong, G.; Williams, J.C.

1975-01-01

Unlike many eutectic composites, the Ni--W eutectic exhibits extensive ductility by slip. Furthermore, its properties may be greatly varied by proper heat treatments. Results of studies of deformation in both monotonic and fatigue loading are reported. During monotonic deformation the fiber/matrix interface acts as a source of dislocations at low strains and an obstacle to matrix slip at higher strains. Deforming the quenched-plus-aged eutectic causes planar matrix slip, with the result that matrix slip bands create stress concentrations in the fibers at low strains. The aged eutectic reaches generally higher stress levels for comparable strains than does the as-quenched eutectic, and the failure strains decrease with increasing aging times. For the composites tested in fatigue, the aged eutectic has better high-stress fatigue resistance than the as-quenched material, but for low-stress, high-cycle fatigue their cycles to failure are nearly the same. However, both crack initiation and crack propagation are different in the two conditions, so the coincidence in high-cycle fatigue is probably fortuitous. The effect of matrix strength on composite performance is not simple, since changes in strength may be accompanied by alterations in slip modes and failure processes. (17 fig) (auth)

The formation mechanism of eutectic microstructures in NiAl-Cr composites.

Science.gov (United States)

Tang, Bin; Cogswell, Daniel A; Xu, Guanglong; Milenkovic, Srdjan; Cui, Yuwen

2016-07-20

NiAl-based eutectic alloys, consisting of an ordered bcc matrix (B2) and disordered bcc fibers (A2), have been a subject of intensive efforts aimed at tailoring the properties of many of the currently used nickel-based superalloys. A thermodynamic phase field model was developed on a thermodynamic foundation and fully integrated with a thermo-kinetic database of the Ni-Al-Cr ternary system to elucidate the resulting peculiar eutectic microstructure. Invoking a variation of the liquid/solid interfacial thickness with temperature, we simulated the characteristic sunflower-like eutectic microstructures in the NiAl-Cr composites, consistent with experimental observations. The mechanism that governs the formation of the peculiar eutectic morphology was envisioned from the modeled evolutions associated with six sequential steps. Our calculations show that the conditional spinodal decomposition occurring in sequence could further trim and revise the microstructure of the eutectics by generating fine-domain structures, thereby providing an additional method to explore the novel NiAl-based eutectic composites with tunable properties at elevated temperatures.

Zone Freezing Study for Pyrochemical Process Waste Minimization

Energy Technology Data Exchange (ETDEWEB)

Ammon Williams

2012-05-01

Pyroprocessing technology is a non-aqueous separation process for treatment of used nuclear fuel. At the heart of pyroprocessing lies the electrorefiner, which electrochemically dissolves uranium from the used fuel at the anode and deposits it onto a cathode. During this operation, sodium, transuranics, and fission product chlorides accumulate in the electrolyte salt (LiCl-KCl). These contaminates change the characteristics of the salt overtime and as a result, large volumes of contaminated salt are being removed, reprocessed and stored as radioactive waste. To reduce the storage volumes and improve recycling process for cost minimization, a salt purification method called zone freezing has been proposed at Korea Atomic Energy Research Institute (KAERI). Zone freezing is melt crystallization process similar to the vertical Bridgeman method. In this process, the eutectic salt is slowly cooled axially from top to bottom. As solidification occurs, the fission products are rejected from the solid interface and forced into the liquid phase. The resulting product is a grown crystal with the bulk of the fission products near the bottom of the salt ingot, where they can be easily be sectioned and removed. Despite successful feasibility report from KAERI on this process, there were many unexplored parameters to help understanding and improving its operational routines. Thus, this becomes the main motivation of this proposed study. The majority of this work has been focused on the CsCl-LiCl-KCl ternary salt. CeCl3-LiCl-KCl was also investigated to check whether or not this process is feasible for the trivalent species—surrogate for rare-earths and transuranics. For the main part of the work, several parameters were varied, they are: (1) the retort advancement rate—1.8, 3.2, and 5.0 mm/hr, (2) the crucible lid configurations—lid versus no-lid, (3) the amount or size of mixture—50 and 400 g, (4) the composition of CsCl in the salt—1, 3, and 5 wt%, and (5) the

Parameterizing the competition between homogeneous and heterogeneous freezing in ice cloud formation – polydisperse ice nuclei

Directory of Open Access Journals (Sweden)

D. Barahona

2009-08-01

Full Text Available This study presents a comprehensive ice cloud formation parameterization that computes the ice crystal number, size distribution, and maximum supersaturation from precursor aerosol and ice nuclei. The parameterization provides an analytical solution of the cloud parcel model equations and accounts for the competition effects between homogeneous and heterogeneous freezing, and, between heterogeneous freezing in different modes. The diversity of heterogeneous nuclei is described through a nucleation spectrum function which is allowed to follow any form (i.e., derived from classical nucleation theory or from observations. The parameterization reproduces the predictions of a detailed numerical parcel model over a wide range of conditions, and several expressions for the nucleation spectrum. The average error in ice crystal number concentration was −2.0±8.5% for conditions of pure heterogeneous freezing, and, 4.7±21% when both homogeneous and heterogeneous freezing were active. The formulation presented is fast and free from requirements of numerical integration.

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

Science.gov (United States)

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

2015-01-01

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

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

Directory of Open Access Journals (Sweden)

Lorraine M McGill

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

Eutectic propeties of primitive Earth's magma ocean

Science.gov (United States)

Lo Nigro, G.; Andrault, D.; Bolfan-Casanova, N.; Perillat, J.-P.

2009-04-01

It is widely accepted that the early Earth was partially molten (if not completely) due to the high energy dissipated by terrestrial accretion [1]. After core formation, subsequent cooling of the magma ocean has led to fractional crystallization of the primitive mantle. The residual liquid corresponds to what is now called the fertile mantle or pyrolite. Melting relations of silicates have been extensively investigated using the multi-anvil press, for pressures between 3 and 25 GPa [2,3]. Using the quench technique, it has been shown that the pressure affects significantly the solidus and liquidus curves, and most probably the composition of the eutectic liquid. At higher pressures, up to 65 GPa, melting studies were performed on pyrolite starting material using the laser-heated diamond anvil cell (LH-DAC) technique [4]. However, the quench technique is not ideal to define melting criteria, and furthermore these studies were limited in pressure range of investigation. Finally, the use of pyrolite may not be relevant to study the melting eutectic temperature. At the core-mantle boundary conditions, melting temperature is documented by a single data point on (Mg,Fe)2SiO4 olivine, provided by shock wave experiments at around 130-140 GPa [5]. These previous results present large uncertainties of ~1000 K. The aim of this study is to determine the eutectic melting temperature in the chemically simplified system composed of the two major lower mantle phases, the MgSiO3 perovskite and MgO periclase. We investigated melting in-situ using the laser-heated diamond anvil cell coupled with angle dispersive X-ray diffraction at the ID27 beamline of the ESRF [6]. Melting relations were investigated in an extended P-T range comparable to those found in the Earth's lower mantle, i.e. from 25 to 120 GPa and up to more than 5000 K. Melting was evidenced from (a) disappearance of one of the two phases in the diffraction pattern, (b) drastic changes of the diffraction image itself, and

Ice crystal interspacing in frozen foods

NARCIS (Netherlands)

Sman, van der R.G.M.; Voda, A.; Dalen, van G.; Duijster, A.

2013-01-01

In this paper we show that the ice crystal growth in food and biomaterials is a function of the freezing rate. Our experimental data and literature data on other biomaterials collapse to a single curve, if plotted against the freezing rate. The fitted correlation is compared to scaling rules

Bulk specimen X-ray microanalysis of freeze-fractured, freeze-dried tissues in gerontological research

International Nuclear Information System (INIS)

Nagy, I.

1988-01-01

The rationale for choosing the freeze-fracture freeze-drying (FFFD) method of biological bulk specimen preparation as well as the theoretical and practical problems of this method are treated. FFFD specimens are suitable for quantitative X-ray microanalysis of biologically relevant elements. Although the spatial resolution of this analytical technique is low, the application of properly selected bulk standard crystals as well as the measurement of the intracellular water and dry mass content by means of another method developed in the same laboratory, allow us to obtain useful information about the age-dependent changes of ionic composition in the main intracellular compartments. The paper summarizes the problems with regard to specimen preparation, beam penetration and the quantitative analysis of FFFD specimens. The method has been applied so far mainly for the analysis of intranuclear and intracytoplasmic concentrations of Na, C1 and K in various types of cells and has resulted in a significant contribution to our understanding of the cellular mechanisms of aging. 84 references

Crystallization and structure of chromium cast iron with addition of Mo and Ni; Krystalizacja i struktura zeliwa chromowego z dodatkami Mo i Ni

Energy Technology Data Exchange (ETDEWEB)

Pietrowski, S. [Instytut Inzynierii Materialowej i Technik Bezwiorowych, Politechnika Lodzka, Lodz (Poland)

1998-12-31

The aim of the presented paper is to show the results of examination of the crystallization process using the method of thermal-derivative analysis (ATD) and the structure examination of chromium cast iron, chromium molybdenum c. i. and chromium molybdenum nickel c.i. It was found that molybdenum in amount over 2 wt % causes the crystallization of eutectic carbides M{sub 23}C{sub 6} and M{sub 6}C. The M{sub 23}C{sub 6} carbide crystallizes upon the crystallization of eutectic carbides M{sub 3}C and M{sub 7}C{sub 3}. It is shown that ATD method facilitates both interpretation and control of the crystallization as well as formation of the cast iron structure at the solid state. (author) 14 refs, 16 figs, 5 tabs

Eutectic and solid-state wafer bonding of silicon with gold

International Nuclear Information System (INIS)

Abouie, Maryam; Liu, Qi; Ivey, Douglas G.

2012-01-01

Highlights: ► Eutectic and solid-state Au-Si bonding are compared for both a-Si and c-Si samples. ► Exchange of a-Si and Au layer was observed in both types of bonded samples. ► Use of c-Si for bonding resulted in formation of craters at the Au/c-Si interface. ► Solid-state Au-Si bonding produces better bonds in terms of microstructure. - Abstract: The simple Au-Si eutectic, which melts at 363 °C, can be used to bond Si wafers. However, faceted craters can form at the Au/Si interface as a result of anisotropic and non-uniform reaction between Au and crystalline silicon (c-Si). These craters may adversely affect active devices on the wafers. Two possible solutions to this problem were investigated in this study. One solution was to use an amorphous silicon layer (a-Si) that was deposited on the c-Si substrate to bond with the Au. The other solution was to use solid-state bonding instead of eutectic bonding, and the wafers were bonded at a temperature (350 °C) below the Au-Si eutectic temperature. The results showed that the a-Si layer prevented the formation of craters and solid-state bonding not only required a lower bonding temperature than eutectic bonding, but also prevented spill out of the solder resulting in strong bonds with high shear strength in comparison with eutectic bonding. Using amorphous silicon, the maximum shear strength for the solid-state Au-Si bond reached 15.2 MPa, whereas for the eutectic Au-Si bond it was 13.2 MPa.

Detection of Collapse and Crystallization of Saccharide, Protein and Mannitol Formulations by Optical Fibers in Lyophilization

Science.gov (United States)

Horn, Jacqueline; Friess, Wolfgang

2018-01-01

The collapse temperature (Tc) and the glass transition temperature of freeze-concentrated solutions (Tg’) as well as the crystallization behavior of excipients are important physicochemical characteristics which guide the cycle development in freeze-drying. The most frequently used methods to determine these values are differential scanning calorimetry (DSC) and freeze-drying microscopy (FDM). The objective of this study was to evaluate the optical fiber system (OFS) unit as alternative tool for the analysis of Tc, Tg’ and crystallization events. The OFS unit was also tested as a potential online monitoring tool during freeze-drying. Freeze/thawing and freeze-drying experiments of sucrose, trehalose, stachyose, mannitol and highly concentrated IgG1 and lysozyme solutions were carried out and monitored by the OFS. Comparative analyses were performed by DSC and FDM. OFS and FDM results correlated well. The crystallization behavior of mannitol could be monitored by the OFS during freeze/thawing as it can be done by DSC. Online monitoring of freeze-drying runs detected collapse of amorphous saccharide matrices. The OFS unit enabled the analysis of both Tc and crystallization processes, which is usually carried out by FDM and DSC. The OFS can hence be used as novel measuring device. Additionally, detection of these events during lyophilization facilitate online-monitoring. Thus the OFS is a new beneficial tool for the development and monitoring of freeze-drying processes.

Detection of Collapse and Crystallization of Saccharide, Protein, and Mannitol Formulations by Optical Fibers in Lyophilization

Directory of Open Access Journals (Sweden)

Jacqueline Horn

2018-01-01

Full Text Available The collapse temperature (Tc and the glass transition temperature of freeze-concentrated solutions (Tg' as well as the crystallization behavior of excipients are important physicochemical characteristics which guide the cycle development in freeze-drying. The most frequently used methods to determine these values are differential scanning calorimetry (DSC and freeze-drying microscopy (FDM. The objective of this study was to evaluate the optical fiber system (OFS unit as alternative tool for the analysis of Tc, Tg' and crystallization events. The OFS unit was also tested as a potential online monitoring tool during freeze-drying. Freeze/thawing and freeze-drying experiments of sucrose, trehalose, stachyose, mannitol, and highly concentrated IgG1 and lysozyme solutions were carried out and monitored by the OFS. Comparative analyses were performed by DSC and FDM. OFS and FDM results correlated well. The crystallization behavior of mannitol could be monitored by the OFS during freeze/thawing as it can be done by DSC. Online monitoring of freeze-drying runs detected collapse of amorphous saccharide matrices. The OFS unit enabled the analysis of both Tc and crystallization processes, which is usually carried out by FDM and DSC. The OFS can hence be used as novel measuring device. Additionally, detection of these events during lyophilization facilitates online-monitoring. Thus the OFS is a new beneficial tool for the development and monitoring of freeze-drying processes.

Graphite crystals grown within electromagnetically levitated metallic droplets

International Nuclear Information System (INIS)

Amini, Shaahin; Kalaantari, Haamun; Mojgani, Sasan; Abbaschian, Reza

2012-01-01

Various graphite morphologies were observed to grow within the electromagnetically levitated nickel–carbon melts, including primary flakes and spheres, curved surface graphite and eutectic flakes, as well as engulfed and entrapped particles. As the supersaturated metallic solutions were cooled within the electromagnetic (EM) levitation coil, the primary graphite flakes and spheres formed and accumulated near the periphery of the droplet due to EM circulation. The primary graphite islands, moreover, nucleated and grew on the droplet surface which eventually formed a macroscopic curved graphite crystal covering the entire liquid. Upon further cooling, the liquid surrounding the primary graphite went under a coupled eutectic reaction while the liquid in the center formed a divorced eutectic due to EM mixing. This brought about the formation of graphite fine flakes and agglomerated particles close to the surface and in the center of the droplet, respectively. The graphite morphologies, growth mechanisms, defects, irregularities and growth instabilities were interpreted with detailed optical and scanning electron microscopies.

Natural deep eutectic solvents as new potential media for green technology

International Nuclear Information System (INIS)

Dai, Yuntao; Spronsen, Jaap van; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae

2013-01-01

Highlights: ► Natural products were used as a source for deep eutectic solvents and ionic liquids. ► We define own chemical and physical properties of natural deep eutectic solvents. ► Interaction between natural deep eutectic solvents and solutes was confirmed by NMR. ► The developed natural deep eutectic solvents were applied as green media. - Abstract: Developing new green solvents is one of the key subjects in Green Chemistry. Ionic liquids (ILs) and deep eutectic solvents, thus, have been paid great attention to replace current harsh organic solvents and have been applied to many chemical processing such as extraction and synthesis. However, current ionic liquids and deep eutectic solvents have still limitations to be applied to a real chemical industry due to toxicity against human and environment and high cost of ILs and solid state of most deep eutectic solvents at room temperature. Recently we discovered that many plant abundant primary metabolites changed their state from solid to liquid when they were mixed in proper ratio. This finding made us hypothesize that natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms and tested a wide range of natural products, which resulted in discovery of over 100 NADES from nature. In order to prove deep eutectic feature the interaction between the molecules was investigated by nuclear magnetic resonance spectroscopy. All the tested NADES show clear hydrogen bonding between components. As next step physical properties of NADES such as water activity, density, viscosity, polarity and thermal properties were measured as well as the effect of water on the physical properties. In the last stage the novel NADES were applied to the solubilization of wide range of biomolecules such as non-water soluble bioactive natural products, gluten, starch, and DNA. In most cases the solubility of the biomolecules evaluated in this study was greatly higher than water. Based on the

Natural deep eutectic solvents as new potential media for green technology

Energy Technology Data Exchange (ETDEWEB)

Dai, Yuntao [Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden (Netherlands); Spronsen, Jaap van; Witkamp, Geert-Jan [Laboratory for Process Equipment, Delft University of Technology, Delft (Netherlands); Verpoorte, Robert [Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden (Netherlands); Choi, Young Hae, E-mail: y.choi@chem.leidenuniv.nl [Natural Products Laboratory, Institute of Biology, Leiden University, 2300 RA Leiden (Netherlands)

2013-03-05

Highlights: ► Natural products were used as a source for deep eutectic solvents and ionic liquids. ► We define own chemical and physical properties of natural deep eutectic solvents. ► Interaction between natural deep eutectic solvents and solutes was confirmed by NMR. ► The developed natural deep eutectic solvents were applied as green media. - Abstract: Developing new green solvents is one of the key subjects in Green Chemistry. Ionic liquids (ILs) and deep eutectic solvents, thus, have been paid great attention to replace current harsh organic solvents and have been applied to many chemical processing such as extraction and synthesis. However, current ionic liquids and deep eutectic solvents have still limitations to be applied to a real chemical industry due to toxicity against human and environment and high cost of ILs and solid state of most deep eutectic solvents at room temperature. Recently we discovered that many plant abundant primary metabolites changed their state from solid to liquid when they were mixed in proper ratio. This finding made us hypothesize that natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms and tested a wide range of natural products, which resulted in discovery of over 100 NADES from nature. In order to prove deep eutectic feature the interaction between the molecules was investigated by nuclear magnetic resonance spectroscopy. All the tested NADES show clear hydrogen bonding between components. As next step physical properties of NADES such as water activity, density, viscosity, polarity and thermal properties were measured as well as the effect of water on the physical properties. In the last stage the novel NADES were applied to the solubilization of wide range of biomolecules such as non-water soluble bioactive natural products, gluten, starch, and DNA. In most cases the solubility of the biomolecules evaluated in this study was greatly higher than water. Based on the

Solvent-free preparation of co-crystals of phenazine and acridine with vanillin

Energy Technology Data Exchange (ETDEWEB)

Braga, Dario, E-mail: dario.braga@unibo.it [Dipartimento di Chimica ' G.Ciamician' , Universita degli studi di Bologna, Via Selmi 2, 40126 Bologna (Italy); Grepioni, Fabrizia; Maini, Lucia; Mazzeo, Paolo P.; Rubini, Katia [Dipartimento di Chimica ' G.Ciamician' , Universita degli studi di Bologna, Via Selmi 2, 40126 Bologna (Italy)

2010-08-10

Co-crystals of phenazine and acridine with vanillin have been obtained by solvent-free reaction or thermal treatment of the solid reactants: their structures, thermal behaviour and eutectic formation have been investigated via single crystal X-ray diffraction, differential scanning calorimetry (DSC), variable temperature X-ray powder diffraction and hot-stage microscopy (HSM). Polymorph screening of the reagents has also been carried out.

Solvent-free preparation of co-crystals of phenazine and acridine with vanillin

International Nuclear Information System (INIS)

Braga, Dario; Grepioni, Fabrizia; Maini, Lucia; Mazzeo, Paolo P.; Rubini, Katia

2010-01-01

Co-crystals of phenazine and acridine with vanillin have been obtained by solvent-free reaction or thermal treatment of the solid reactants: their structures, thermal behaviour and eutectic formation have been investigated via single crystal X-ray diffraction, differential scanning calorimetry (DSC), variable temperature X-ray powder diffraction and hot-stage microscopy (HSM). Polymorph screening of the reagents has also been carried out.

A new technique for direct traceability of contact thermometry Co-C eutectic cells to the ITS-90

Energy Technology Data Exchange (ETDEWEB)

Failleau, G.; Deuzé, T.; Bourson, F.; Briaudeau, S.; Sadli, M. [Laboratoire Commun de Métrologie LNE-Cnam, 61 rue du Landy 93210 La Plaine Saint Denis (France)

2013-09-11

The eutectic Co-C melting point is a promising system to serve as a thermometric fixed-point in the temperature range above 1084.62 °C (copper freezing point). During the last decade, LNE-Cnam has developed and characterized some fixed-point devices, based on eutectic Co-C alloy, for applications to contact and radiation thermometry. Above 962 °C, the ITS-90 is realized by radiation thermometry by the extrapolation from a Ag, Au or Cu fixed point using the Planck law for radiation. So the only way for assigning a temperature in the scale to a Co-C cell (∼1324 °C) is by radiation thermometry. An indirect method is commonly used to assign a temperature to a high-temperature fixed point (HTFP) cell designed for contact thermometry is to fill a pyrometric cell with the same mixture as the contact thermometry cell. In this case, the temperature assigned to the pyrometric cell is attributed to the contact cell. This paper describes a direct method allowing the determination of the melting temperature realized by a 'contact thermometry' Co-C cell by comparison to a 'radiation thermometry' Co-C cell whose melting temperature was assigned in accordance to the scale by extrapolation from the Cu point. In addition, the same Co-C cell is studied with a standard Pt/Pd thermocouple.

Application of SEM/EBSD and FEG-TEM/CBED to determine eutectic solidification mechanisms

International Nuclear Information System (INIS)

Nogita, K.; Dahle, A.K.; Drennan, J.

2002-01-01

Full text: This study shows the application of electron backscatter diffraction (EBSD) in SEM and convergent beam electron diffraction (CBED) in FEG-TEM to determine eutectic nucleation and growth in hypoeutectic Al-Si foundry alloys. Because the eutectic reaction is often the final stage of solidification it can be expected to have a significant impact on the formation of casting defects, particularly porosity. Previous EBSD work by Nogita and Dahle (2001), Dahle et al (2001), has shown that the eutectic nucleates on the primary phase in the unmodified alloy, and eutectic grains are nucleated in the intergranular liquid, instead of filling the dendrite envelopes, when Sr or Sb is added. However, the orientation relationship between silicon and aluminium in the eutectic has so far not been determined because of difficulties with sample preparation for EBSD and also detection limitations of Kikuchi refraction of silicon and aluminium, particularly in modified alloys with a refined eutectic. The combination of the EBSD technique in SEM and CBED in TEM analyses can provide crystallographic orientation relationships between primary aluminium dendrites, eutectic aluminium and silicon, which are important to explicitly define the solidification mode of the eutectic in hypoeutectic Al-Si alloys. These relationships are influenced, and altered, by the addition of certain elements. This paper also describes the sample preparation techniques for SEM and TEM for samples with different eutectic structures. The advantages the techniques are discussed. Copyright (2002) Australian Society for Electron Microscopy Inc

Experimental and Theoretical Investigations of the Solidification of Eutectic Al-Si Alloy

Science.gov (United States)

Sen, S.; Catalina, A. V.; Rose, M. Franklin (Technical Monitor)

2001-01-01

The eutectic alloys have a wide spectrum of applications due to their good castability and physical and mechanical properties. The interphase spacing resulting during solidification is an important microstructural feature that significantly influences the mechanical behavior of the material. Thus, knowledge of the evolution of the interphase spacing during solidification is necessary in order to properly design the solidification process and optimize the material properties. While the growth of regular eutectics is rather well understood, the irregular eutectics such as Al-Si or Fe-graphite exhibit undercoolings and lamellar spacings much larger than those theoretically predicted. Despite of a considerable amount of experimental and theoretical work a clear understanding of the true mechanism underlying the spacing selection in irregular eutectics is yet to be achieved. A new experimental study of the solidification of the eutectic Al-Si alloy will be reported in this paper. The measured interface undercoolings and lamellar spacing will be compared to those found in the literature in order to get more general information regarding the growth mechanism of irregular eutectics. A modification of the present theory of the eutectic growth is also proposed. The results of the modified mathematical model, accounting for a non-isothermal solid/liquid interface, will be compared to the experimental measurements.

Containerless solidification of acoustically levitated Ni-Sn eutectic alloy

Energy Technology Data Exchange (ETDEWEB)

Geng, D.L.; Xie, W.J.; Wei, B. [Northwestern Polytechnical University, Department of Applied Physics, Xi' an (China)

2012-10-15

Containerless solidification of Ni-18.7at%Sn eutectic alloy has been achieved with a single-axis acoustic levitator. The temperature, motion, and oscillation of the sample were monitored by a high speed camera. The temperature of the sample can be determined from its image brightness, although the sample moves vertically and horizontally during levitation. The experimentally observed frequency of vertical motion is in good agreement with theoretical prediction. The sample undergoes shape oscillation before solidification finishes. The solidification microstructure of this alloy consists of a mixture of anomalous eutectic plus regular lamellar eutectic. This indicates the achievement of rapid solidification under acoustic levitation condition. (orig.)

Intact preservation of environmental samples by freezing under an alternating magnetic field.

Science.gov (United States)

Morono, Yuki; Terada, Takeshi; Yamamoto, Yuhji; Xiao, Nan; Hirose, Takehiro; Sugeno, Masaya; Ohwada, Norio; Inagaki, Fumio

2015-04-01

The study of environmental samples requires a preservation system that stabilizes the sample structure, including cells and biomolecules. To address this fundamental issue, we tested the cell alive system (CAS)-freezing technique for subseafloor sediment core samples. In the CAS-freezing technique, an alternating magnetic field is applied during the freezing process to produce vibration of water molecules and achieve a stable, super-cooled liquid phase. Upon further cooling, the temperature decreases further, achieving a uniform freezing of sample with minimal ice crystal formation. In this study, samples were preserved using the CAS and conventional freezing techniques at 4, -20, -80 and -196 (liquid nitrogen) °C. After 6 months of storage, microbial cell counts by conventional freezing significantly decreased (down to 10.7% of initial), whereas that by CAS-freezing resulted in minimal. When Escherichia coli cells were tested under the same freezing conditions and storage for 2.5 months, CAS-frozen E. coli cells showed higher viability than the other conditions. In addition, an alternating magnetic field does not impact on the direction of remanent magnetization in sediment core samples, although slight partial demagnetization in intensity due to freezing was observed. Consequently, our data indicate that the CAS technique is highly useful for the preservation of environmental samples. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Precision of the eutectic points determination by the isopleths

Energy Technology Data Exchange (ETDEWEB)

Lutsyk, V I; Sumkina, O G; Savinov, V V; Zelenaya, A E, E-mail: vluts@pres.bscnet.ru [Physical Problems Department, Buryat Scientific Center of RAS (Siberian Branch), 8 Sakhyanova st., Ulan-Ude, 670047 (Russian Federation)

2011-10-29

An imitation of quaternary eutectic point searching techniques by means of two-dimensional sections set construction (tie-lines method) was made, using the model of T-x-y-z diagram of eutectic type without solid-phases solubility as an example. The errors, appearing in sections graphics of experimentally studied systems, are analyzed.

Adaptive and freeze-tolerant heteronetwork organohydrogels with enhanced mechanical stability over a wide temperature range

Science.gov (United States)

Gao, Hainan; Zhao, Ziguang; Cai, Yudong; Zhou, Jiajia; Hua, Wenda; Chen, Lie; Wang, Li; Zhang, Jianqi; Han, Dong; Liu, Mingjie; Jiang, Lei

2017-06-01

Many biological organisms with exceptional freezing tolerance can resist the damages to cells from extra-/intracellular ice crystals and thus maintain their mechanical stability at subzero temperatures. Inspired by the freezing tolerance mechanisms found in nature, here we report a strategy of combining hydrophilic/oleophilic heteronetworks to produce self-adaptive, freeze-tolerant and mechanically stable organohydrogels. The organohydrogels can simultaneously use water and oil as a dispersion medium, and quickly switch between hydrogel- and organogel-like behaviours in response to the nature of the surrounding phase. Accordingly, their surfaces display unusual adaptive dual superlyophobic in oil/water system (that is, they are superhydrophobic under oil and superoleophobic under water). Moreover, the organogel component can inhibit the ice crystallization of the hydrogel component, thus enhancing the mechanical stability of organohydrogel over a wide temperature range (-78 to 80 °C). The organohydrogels may have promising applications in complex and harsh environments.

Freezing of liquid alkali metals as screened ionic plasmas

International Nuclear Information System (INIS)

Badirkhan, Z.; Rovere, M.; Tosi, M.P.

1990-08-01

The relationship between Wigner crystallization of the classical ionic plasma and the liquid-solid transition of alkali metals is examined within the density wave theory of freezing. Freezing of the classical plasma on a rigid neutralizing background into the bcc structure is first re-evaluated, in view of recent progress in the determination of its thermodynamic functions by simulation and of the known difficulties of the theory relating to the order parameter at the (200) star of reciprocal lattice vectors. Freezing into the fcc structure is also considered in this context and found to be unfavoured. On allowing for long-wavelength deformability of the background, the ensuing appearance of a volume change on freezing into the bcc structure is accompanied by reduced stability of the fluid phase and by an increase in the entropy of melting. Freezing of alkali metals into the bcc structure is next evaluated, taking their ionic pair structure as that of an ionic plasma reference fluid screened by conduction electrons and asking that the correct ionic coupling strength at liquid-solid coexistence should be approximately reproduced. The ensuring values of the volume and entropy changes across the phase transition, as estimated from the theory by two alternative routes, are in reasonable agreement with experiment. The order parameters of the phase transition, excepting the (200) one, conform rather closely to a Gaussian behaviour and yield a Lindemann ratio in reasonable agreement with the empirical value for melting of bcc crystals. It is suggested that ionic ordering at the (200) star in the metal may be (i) assisted by medium range ordering in the conduction electrons, as indicated by differences in X-ray and neutron diffraction intensities from the liquid, and/or (ii) quite small in the hot bcc solid. Such a possible premelting behaviour of bcc metals should be worth testing experimentally by diffraction. (author). 48 refs, 1 fig., 1 tab

Crystallization of pyroxene phases and physico-chemical properties of glass-ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic glass system

Energy Technology Data Exchange (ETDEWEB)

Salman, S.M.; Salama, S.N.; Abo-Mosallam, H.A., E-mail: abomosallam@yahoo.com.au

2015-01-15

The crystallization characteristics, crystalline phase assemblages and solid solution phases developed due to thermally crystallized glasses based on the Li{sub 2}SiO{sub 3}–Li{sub 2}Si{sub 2}O{sub 5}–LiCrSi{sub 2}O{sub 6} (1028 ± 3 °C) eutectic glass system by replacing some trivalent oxides instead of Cr{sub 2}O{sub 3} were investigated. The microhardness and chemical durability of the glass-ceramics were also determined. Lithium meta and disilicate (Li{sub 2}SiO{sub 3} and Li{sub 2}Si{sub 2}O{sub 5}), lithium gallium silicate (LiGaSiO{sub 4}), and varieties of pyroxene phases, including Cr-pyroxene phase, i.e. lithium-kosmochlor (LiCrSi{sub 2}O{sub 6}), lithium aluminum silicate (LiAlSi{sub 2}O{sub 6}), lithium indium silicate (LiInSi{sub 2}O{sub 6}) and pyroxene solid solution of Li-aegerine type [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}] were the main crystalline phases formed in the crystallized glasses. There is no evidence for the formation of solid solution or liquid immiscibility gaps between LiAlSi{sub 2}O{sub 6} or LiInSi{sub 2}O{sub 6} phases and LiCrSi{sub 2}O{sub 6} phase. However, LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} components were accommodated in the pyroxene structure under favorable conditions of crystallization to form monomineralic pyroxene solid solution phase of the probably formula [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}]. The type and compatibility of the crystallized phases are discussed in relation to the compositional variation of the glasses and heat-treatment applied. The microhardness values of the crystalline materials ranged between 5282 and 6419 MPa while, the results showed that the chemical stability of the glass-ceramics was better in alkaline than in acidic media. - Highlights: • Glass ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic (1028 ± 3 °C) glass were prepared. • LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} phases form monomineralic pyroxene solid

Freeze-drying wet digital prints: An option for salvage?

International Nuclear Information System (INIS)

Juergens, M C; Schempp, N

2010-01-01

On the occasion of the collapse of the Historical Archive of the City of Cologne in March 2009 and the ensuing salvage effort, questions were raised about the use of freeze-drying for soaked digital prints, a technique that has not yet been evaluated for these materials. This study examines the effects of immersion, air-drying, drying in a blotter stack, freezing and freeze-drying on 35 samples of major digital printing processes. The samples were examined visually before, during and after testing; evaluation of the results was qualitative. Results show that some prints were already damaged by immersion alone (e.g. bleeding inks and soluble coatings) to the extent that the subsequent choice of drying method made no significant difference any more. For those samples that did survive immersion, air-drying proved to be crucial for water-sensitive prints, since any contact with the wet surface caused serious damage. Less water-sensitive prints showed no damage throughout the entire procedure, regardless of drying method. Some prints on coated media suffered from minor surface disruption up to total delamination of the surface coating due to the formation of ice crystals during shock-freezing. With few exceptions, freeze-drying did not cause additional damage to any of the prints that hadn't already been damaged by freezing. It became clear that an understanding of the process and materials is important for choosing an appropriate drying method.

Study on the morphology of Pb-Sn eutectics

International Nuclear Information System (INIS)

Ambrozio Filho, F.; Gentile, E.F.

1976-01-01

The influence of factors such as rate of growth of the solid phase, thermal gradient in the liquid and presence of impurities on the solidification of eutectic structures is studied. To emphasize certain aspects of the basic concept, the technique of unidirectional cooling was used in a specially constructed apparatus. Micrographs of the structure obtained with the eutectic Pb-Sn alloy are shown and a purely qualitative analysis of the factors described is given [pt

Antimony Influence on Shape of Eutectic Silicium in Al-Si Based Alloys

Directory of Open Access Journals (Sweden)

Bolibruchová D.

2017-12-01

Full Text Available Liquid AI-Si alloys are usually given special treatments before they are cast to obtain finer or modified matrix and eutectic structures, leading to improved properties. For many years, sodium additions to hypoeutectic and eutectic AI-Si melts have been recognized as the most effective method of modifying the eutectic morphology, although most of the group IA or IIA elements have significant effects on the eutectic structure. Unfortunately, many of these approaches also have associated several founding difficulties, such as fading, forming dross in presence of certain alloying elements, reduced fluidity, etc. ln recent years, antimony additions to AI-Si castings have attracted considerable attention as an alternative method of refining the eutectic structure. Such additions eliminate many of the difficulties listed above and provide permanent (i.e. non-fading refining ability. In this paper, the authors summarize work on antimony treatment of Al-Si based alloys.

Freeze-drying behaviour of pasteurized whole egg

International Nuclear Information System (INIS)

Melike Sakin; Merve Samli; Gizem Kor, A.; Figen Kaymak-Ertekin

2009-01-01

Because it provides full nutritional and certain desirable functional attributes, egg products are widely used as ingredients in many food products. Dried egg is especially valuable for being stable, easily mixable and having a long shelf life. It is necessary to know the effects of drying conditions onto the moisture removal behaviour and the functional properties of the powder product, to serve the egg powder as an alternative. An experimental study was conducted to achieve an understanding of the freeze-drying behaviour of pasteurized whole egg having 24% dry solids. In order to determine the moisture removal behaviour; the percent moisture loss (w/w), the average moisture content and the drying rates were obtained, the drying curves were developed and total drying times were determined, also the movement of the dry-wet boundary between the frozen layer and the dry porous layer formed by sublimation of ice crystals were investigated during a complete process. The physical properties of pasteurized whole egg such as; colour, water activity (a w ), the morphological structure (through SEM analysis) and functional properties (foam stability and dissolubility) were determined. The net colour change (ΔE) was about 22, independent of layer thickness. The water activity decreased to 0.22 at the end of drying. The SEM images of freeze-dried and slightly milled egg powder samples at magnification levels of 500 and 1000 showed the porous structure caused by sublimation of ice crystals generated within the egg structure during air blast freezing. The dissolubility and foaming capacity of powder egg were observed to be lower compared to those of pasteurized liquid egg. (author)

Deep Eutectic Solvent Synthesis of LiMnPO₄/C Nanorods as a Cathode Material for Lithium Ion Batteries.

Science.gov (United States)

Wu, Zhi; Huang, Rong-Rong; Yu, Hang; Xie, Yong-Chun; Lv, Xiao-Yan; Su, Jing; Long, Yun-Fei; Wen, Yan-Xuan

2017-02-06

Olivine-type LiMnPO₄/C nanorods were successfully synthesized in a chloride/ethylene glycol-based deep eutectic solvent (DES) at 130 °C for 4 h under atmospheric pressure. As-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and electrochemical tests. The prepared LiMnPO₄/C nanorods were coated with a thin carbon layer (approximately 3 nm thick) on the surface and had a length of 100-150 nm and a diameter of 40-55 nm. The prepared rod-like LiMnPO₄/C delivered a discharge capacity of 128 mAh·g -1 with a capacity retention ratio of approximately 93% after 100 cycles at 1 C. Even at 5 C, it still had a discharge capacity of 106 mAh·g -1 , thus exhibiting good rate performance and cycle stability. These results demonstrate that the chloride/ethylene glycol-based deep eutectic solvents (DES) can act as a new crystal-face inhibitor to adjust the oriented growth and morphology of LiMnPO₄. Furthermore, deep eutectic solvents provide a new approach in which to control the size and morphology of the particles, which has a wide application in the synthesis of electrode materials with special morphology.

Effect of Ni on eutectic structural evolution in hypereutectic Al-Mg2Si cast alloys

International Nuclear Information System (INIS)

Li Chong; Wu Yaping; Li Hui; Wu Yuying; Liu Xiangfa

2010-01-01

Research highlights: → By the injection of rod-like NiAl 3 phase in Al-Mg 2 Si alloys, Al-Mg 2 Si binary eutectic structure gradually evolves into Al-Mg 2 Si-NiAl 3 ternary eutectic. → The ternary eutectic presents a unique double rod structure that rod-like NiAl 3 and Mg 2 Si uniformly distribute in Al matrix. → The mechanism of structural evolution was analyzed in terms of the detailed microstructural observations. → The high temperature (350 deg. C) tensile strength of the alloy increases by 23% due to the eutectic structural evolution. - Abstract: The aim of this work is to investigate the eutectic structural evolution of hypereutectic Al-20% Mg 2 Si with Ni addition under a gravity casting process. Three-dimensional morphologies of eutectic phases were observed in detail using field emission scanning electron microscopy, after Al matrix was removed by deep etching or extraction. The results show that Al-Mg 2 Si binary eutectic gradually evolves into Al-Mg 2 Si-NiAl 3 ternary eutectic with the increase of Ni content, and flake-like eutectic Mg 2 Si transforms into rods. The ternary eutectic presents a unique double rod structure that rod-like NiAl 3 and Mg 2 Si uniformly distribute in Al matrix. Further, the high temperature (350 deg. C) tensile strength of the alloy increases by 23% due to the eutectic structure evolution, and the mechanism of structural evolution was discussed and analyzed in terms of the detailed microstructural observations.

Coatings for directional eutectics

Science.gov (United States)

Rairden, J. R.; Jackson, M. R.

1976-01-01

Coatings developed to provide oxidation protection for the directionally-solidified eutectic alloy NiTaC-B (4.4 weight percent Cr) were evaluated. Of seven Co-, Fe- and Ni-base coatings that were initially investigated, best resistance to cyclic oxidation was demonstrated by duplex coatings fabricated by depositing a layer of NiCrAl(Y) by vacuum evaporation from an electron beam source followed by deposition of an Al overlayer using the pack cementation process. It was found that addition of carbon to the coating alloy substantially eliminated the problem of fiber denudation in TaC-type eutectic alloys. Burner rig cycled NiTaC-B samples coated with Ni-20Cr-5Al-0.1C-0.1Y+Al and rupture-tested at 1100 deg C performed as well as or better than uncoated, vacuum cycled and air-tested NiTaC-13; however, a slight degradation with respect to uncoated material was noted in air-stress rupture tests at 870 deg C for both cycled and uncycled samples.

Crystallization of cristobalite from glass phase in mullite ceramics with excess SiO{sub 2} compositions; Sirika kajo muraito seramikkusu chu no garasuso no kesshoka kyodo

Energy Technology Data Exchange (ETDEWEB)

Sato, Takashi; Sugai, Mikio; Nakagawa, Zenbee [Akita University, Akita (Japan). Faculty of Engineering and Resource Science; Sawabe, Yoshinari [Sumitomo Chemical Corp., Ibaraki (Japan). Tsukuba Research Laboratory; Oya, Yutaka [Gifu University, Gifu (Japan). Faculty of Engineering

1999-09-01

Crystallization of glass phase to cristobalite was investigated in mullite-glass ceramics with excess SiO{sub 2} compositions (5.3-16.4 mass %), namely, higher than stoichiometric mullite. Starting powders were prepared by alkoxide hydrolysis method. Compact specimens were sintered at 1600 degree C above the eutectic temperature (1587 degree C) for 2 h. Crystallization treatment was carried out at 1500 degree C, below the eutectic temperature, for times from 4 h to 96 h. Crystallization of glass phase proceeded from the surface of the specimen toward its inner part, in linear dependence on the annealing time. At the polished surface of the specimen, crystallization started in large glass pockets and the crystallized area extended spherically toward the inner part. This phenomenon suggests that nucleation occurs at the minimum parts in the elastic energy generated by the volume change involved in the crystallization of glass phase to cristobalite. (author)

Characterization of tin films synthesized from ethaline deep eutectic solvent

International Nuclear Information System (INIS)

Ghosh, Swatilekha; Roy, Sudipta

2014-01-01

Highlights: • Tin deposition was achieved by galvanostatic method on the basic substrates from ethaline deep eutectic solvent without use of any additives. • The current potential behaviour of tin system changes with increase in concentration of hydrated tin chloride in ethaline. • The deposition rate in ethaline display three times lower value compared to aqueous electrolytes. • Fine grained crystals of 62 ± 10 nm were obtained for tin deposits. • The deposition process is economical and can be adapted for industrial applications. - Abstract: Tin (Sn) films were electrodeposited by galvanostatic method from ethaline deep eutectic solvent (DES), without any additives. The effect of various deposition parameters on the microstructure was studied. With increase in metal salt concentration from 0.01 to 0.1 M, changes in current–potential behaviour were observed in the polarization scans. This might be due to the existence of [SnCl 3 ] − , [Sn 2 Cl 5 ] − complexes in ethaline DES. Smooth and homogeneous deposits were obtained on a steel substrate surface by applying current density of 1.57 × 10 −3 A/cm 2 at 25 °C. Under these conditions the deposition rate was found to be 0.1 ± 10% μm/min and current efficiency was obtained as 84 ± 3%. XRD analysis of the deposit confirmed the polycrystalline tetragonal structure with mostly (2 0 0) orientation having a crystallite size about 62 ± 16% nm along with an internal strain of 0.0031 ± 22%. The present deposition method is simple, economical and can be adapted for industrial applications

Effect of length scale on mechanical properties of Al-Cu eutectic alloy

Science.gov (United States)

Tiwary, C. S.; Roy Mahapatra, D.; Chattopadhyay, K.

2012-10-01

This paper attempts a quantitative understanding of the effect of length scale on two phase eutectic structure. We first develop a model that considers both the elastic and plastic properties of the interface. Using Al-Al2Cu lamellar eutectic as model system, the parameters of the model were experimentally determined using indentation technique. The model is further validated using the results of bulk compression testing of the eutectics having different length scales.

Magnetic anisotropy induced by crystallographic orientation and morphological alignment in directionally-solidified eutectic Mn-Sb alloy

Energy Technology Data Exchange (ETDEWEB)

Lou, Chang-Sheng [School of Materials Science and Engineering, Shenyang Ligong University, Shenyang 110159 (China); Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Liu, Tie, E-mail: liutie@epm.neu.edu.cn [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China); Dong, Meng; Wu, Chun; Shao, Jian-Guo; Wang, Qiang [Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang 110819 (China)

2017-02-15

The influences of the crystallographic orientation and morphological alignment upon the magnetic anisotropic behavior of polycrystalline materials were investigated. Microstructures obtained in eutectic Mn-Sb alloys via directional solidification simultaneously displayed crystallographic orientation and morphological alignment. Both the crystallographic orientation and the morphological alignment were able to induce magnetic anisotropy in the alloys, wherein the influence of the crystallographic orientation and the morphological alignment upon the magnetic anisotropic behavior of the alloys strongly depended upon their directions and exhibited either mutual promotion or competition. These findings may provide useful guidance for the fabrication design of functional magnetic materials. - Highlights: • We study effects of orientation in crystal and morphology on magnetic anisotropy. • Both orientation in crystal and morphology can induce magnetic anisotropy. • Their effects depend on direction and exhibit either mutual promotion or competition.

Physicochemical interaction mechanism between nanoparticles and tetrasaccharides (stachyose) during freeze-drying.

Science.gov (United States)

Kamiya, Seitaro; Nakashima, Kenichiro

2017-12-01

Nanoparticle suspensions are thermodynamically unstable and subject to aggregation. Freeze-drying on addition of saccharides is a useful method for preventing aggregation. In the present study, tetrasaccharides (stachyose) was employed as an additive. In addition, we hypothesize the interactive mechanism between stachyose and the nanoparticles during freeze-drying for the first time. The mean particle size of the rehydrated freeze-dried stachyose-containing nanoparticles (104.7 nm) was similar to the initial particle size before freeze-drying (76.8 nm), indicating that the particle size had been maintained. The mean particle size of the rehydrated normal-dried stachyose-containing nanoparticles was 222.2 nm. The powder X-ray diffraction of the freeze-dried stachyose-containing nanoparticles revealed a halo pattern. The powder X-ray diffraction of the normally dried stachyose-containing nanoparticles produced mainly a halo pattern and a partial peak. These results suggest an interaction between the nanoparticles and stachyose, and that this relationship depends on whether the mixture is freeze-dried or dried normally. In the case of normal drying, although most molecules cannot move rapidly thereby settling irregularly, some stachyose molecules can arrange regularly leading to some degree of crystallization and potentially some aggregation. In contrast, during freeze-drying, the moisture sublimed, while the stachyose molecules and nanoparticles were immobilized in the ice. After sublimation, stachyose remained in the space occupied by water and played the role of a buffer material, thus preventing aggregation.

Directional solidification and characterization of the Al Nb2 - Al3 Nb eutectic system

International Nuclear Information System (INIS)

Trevisan, Eduardo A.O.; Andreotti, Fabio; Caram, Rubens

1996-01-01

The manufacturing of components to operate at high temperatures requires the use of metallic materials which can keep satisfactory mechanical and chemical properties, even at temperatures beyond 1000 deg C. An interesting alternative is the use of directionally solidified eutectic alloys. The eutectic alloy solidification makes possible the production of 'in situ' composite. A potentially useful system for manufacturing structural materials is the Al-Nb eutectic system. The aim of this work is to present the directional solidification of the Al-Nb eutectic alloy. (author)

Crystallization of Trehalose in Frozen Solutions and its Phase Behavior during Drying

Energy Technology Data Exchange (ETDEWEB)

Sundaramurthi, Prakash; Patapoff, Thomas W.; Suryanarayanan, Raj (Genentech); (UMM)

2015-02-19

To study the crystallization of trehalose in frozen solutions and to understand the phase transitions during the entire freeze-drying cycle. Aqueous trehalose solution was cooled to -40 C in a custom-designed sample holder. The frozen solution was warmed to -18 C and annealed, and then dried in the sample chamber of the diffractometer. XRD patterns were continuously collected during cooling, annealing and drying. After cooling, hexagonal ice was the only crystalline phase observed. However, upon annealing, crystallization of trehalose dihydrate was evident. Seeding the frozen solution accelerated the solute crystallization. Thus, phase separation of the lyoprotectant was observed in frozen solutions. During drying, dehydration of trehalose dihydrate yielded a substantially amorphous anhydrous trehalose. Crystallization of trehalose, as trehalose dihydrate, was observed in frozen solutions. The dehydration of the crystalline trehalose dihydrate to substantially amorphous anhydrate occurred during drying. Therefore, analyzing the final lyophile will not reveal crystallization of the lyoprotectant during freeze-drying. The lyoprotectant crystallization can only become evident by continuous monitoring of the system during the entire freeze-drying cycle. In light of the phase separation of trehalose in frozen solutions, its ability to serve as a lyoprotectant warrants further investigation.

Investigation of PEG crystallization in frozen PEG-sucrose-water solutions. I. Characterization of the nonequilibrium behavior during freeze-thawing.

Science.gov (United States)

Bhatnagar, Bakul S; Martin, Susan M; Teagarden, Dirk L; Shalaev, Evgenyi Y; Suryanarayanan, Raj

2010-06-01

Our objective was to characterize the nonequilibrium thermal behavior of frozen aqueous solutions containing PEG and sucrose. Aqueous solutions of (i) sucrose (10%, w/v) with different concentrations of PEG (1-20%, w/v), and (ii) PEG (10%, w/v) with different concentrations of sucrose (2-20%, w/v), were cooled to -70 degrees C at 5 degrees C/min and heated to 25 degrees C at 2 degrees C/min in a differential scanning calorimeter. Annealing was performed at temperatures ranging from -50 to -20 degrees C for 2 or 6 h. Similar experiments were also performed in the low-temperature stage of a powder X-ray diffractometer. A limited number of additional DSC experiments were performed wherein the samples were cooled to -100 degrees C. In unannealed systems with a fixed sucrose concentration (10%, w/v), the T'g decreased from -35 to -48 degrees C when PEG concentration was increased from 1% to 20% (w/v). On annealing at -25 degrees C, PEG crystallized. This was evident from the increase in T'g and the appearance of a secondary melting endotherm in the DSC. Low-temperature XRD provided direct evidence of PEG crystallization. Annealing at temperatures crystallization and a devitrification event was observed above the T'g. In unannealed systems with a fixed PEG concentration (10%, w/v), the T'g increased from -50 to -40 degrees C when sucrose concentration was increased from 5% to 50%, w/v. As the annealing time increased (at -25 degrees C), the T'g approached that of a sucrose-water system, reflecting progressive PEG crystallization. A second glass transition at approximately -65 degrees C was evident in unannealed systems [10%, w/v sucrose and 10 (or 20%), w/v PEG] cooled to -100 degrees C. Investigation of the nonequilibrium behavior of frozen PEG-sucrose-water ternary system revealed phase separation in the freeze-concentrate. Annealing facilitated PEG crystallization. (c) 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Immersion Freezing of Aluminas: The Effect of Crystallographic Properties on Ice Nucleation

Science.gov (United States)

King, M.; Chong, E.; Freedman, M. A.

2017-12-01

Atmospheric aerosol particles serve as the nuclei for heterogeneous ice nucleation, a process that allows for ice to form at higher temperatures and lower supersaturations with respect to ice. This process is essential to the formation of ice in cirrus clouds. Heterogeneous ice nucleation is affected by many factors including the composition, crystal structure, porosity, and surface area of the particles. However, these factors are not well understood and, as such, are difficult to account for in climate models. To test the effects of crystal structure on ice nucleation, a system of transition aluminas (Al2O3) that differ only in their crystal structure, despite being compositionally similar, were tested using immersion freezing. Particles were immersed in water and placed into a temperature controlled chamber. Freezing events were then recorded as the chamber was cooled to negative 30 °. Alpha-alumina, which is a member of the hexagonal crystal system, showed a significantly higher temperature at which all particles froze in comparison to other samples. This supports the hypothesis that, since a hexagonal crystal structure is the lowest energy state for ice, hexagonal surface structures would best facilitate ice nucleation. However, a similar sample of hexagonal chi-alumina did not show the same results. Further analysis of the samples will be done to characterize surface structures and composition. These conflicting data sets raise interesting questions about the effect of other surface features, such as surface area and porosity, on ice nucleation.

Freezing for Love

DEFF Research Database (Denmark)

Carroll, Katherine; Kroløkke, Charlotte

2018-01-01

The promise of egg freezing for women’s fertility preservation entered feminist debate in connection with medical and commercial control over, and emancipation from, biological reproduction restrictions. In this paper we explore how women negotiate and make sense of the decision to freeze...... their eggs. Our analysis draws on semi-structured interviews with 16 women from the Midwest and East Coast regions of the USA who froze their eggs. Rather than freezing to balance career choices and ‘have it all’, the women in this cohort were largely ‘freezing for love’ and in the hope of having their ‘own...... healthy baby’. This finding extends existing feminist scholarship and challenges bioethical concerns about egg freezing by drawing on the voices of women who freeze their eggs. By viewing egg freezing as neither exclusively liberation nor oppression or financial exploitation, this study casts egg freezing...

Phase-field model of eutectic growth

International Nuclear Information System (INIS)

Karma, A.

1994-01-01

A phase-field model which describes the solidification of a binary eutectic alloy with a simple symmetric phase diagram is introduced and the sharp-interface limit of this model is explored both analytically and numerically

Solidification behaviors of a single-crystal superalloy under lateral constraints

International Nuclear Information System (INIS)

Zhuangqi Hu; Huaming Wang

1993-01-01

The effect of lateral constraints ahead of solidification interface on the solidification behaviors of a newly developed hot corrosion resistant single-crystal nickel-base superalloy was investigated under commercial single-crystal production conditions. The lateral constraints or section variations ahead of solidification front were found to have drastic influences both on the modes of solidification and the profiles of solute segregation. As lateral constraints were imposed ahead of the directionally solidifying interface, the solidification microstructure of the single-crystal superalloy changed suddenly, through a γ/γ' eutectic-free zone which is characterized by an extremely-fine and highly-developed dendrite network, from the original well-branched dendritic structure to a fine cellular-dendrite or regular cell structure, accompanying which the primary arm spacing, the severity of segregation and the amount of microporosity decreased remarkably. The newly formed cellular dendrite or cell structure transforms always gradually to the initial coarse dendrite structure as the lateral constraint is finally released whether gradually or sharply. Moreover, an abnormal porosity zone was readily observed in the initial section beneath and away from the eutectic-free zone. The solidification microstructural changes were attributed to the drastic dynamical changes in local solidification cooling conditions and in momentum transport during solidification due to the presence of lateral constraint

Nucleation of recrystallisation in castings of single crystal Ni-based superalloys

International Nuclear Information System (INIS)

Mathur, Harshal N.; Panwisawas, Chinnapat; Jones, C. Neil; Reed, Roger C.; Rae, Catherine M.F.

2017-01-01

Recrystallisation in single crystal Ni-based superalloys during solution heat treatment results in a significant cost to the investment casting industry. In this paper two sources of surface nucleation have been identified in the alloy CMSX-4 ® . Firstly, Electron Backscattered Diffraction (EBSD) has revealed micro-grains of γ′, between 2 and 30 μm diameter in the layer of surface eutectic found in the upper part of the casting. These have high angle boundaries with respect to the bulk single crystal and a fraction coarsen during solution heat treatment. Secondly, in the lower regions where surface eutectic does not form, locally deformed regions, 5–20 μm deep, form where the metal adheres to the mould. The local strain causes misorientations up to ≈20° with respect the bulk single crystal, and after heat treatment these regions develop into small grains of similar low-angle misorientations. However, they also form twins to produce further grains which have mobile high-angle boundaries with respect to the bulk single crystal. Experiments have shown that micro-grains at the surface grow to cause full recrystallisation where there is sufficient strain in the bulk material, and by removing these surface defects, recrystallisation can be completely mitigated. Etching of the cast surface is demonstrated to be an effective method of achieving this.

Freezing Bubbles

Science.gov (United States)

Kingett, Christian; Ahmadi, Farzad; Nath, Saurabh; Boreyko, Jonathan

2017-11-01

The two-stage freezing process of a liquid droplet on a substrate is well known; however, how bubbles freeze has not yet been studied. We first deposited bubbles on a silicon substrate that was chilled at temperatures ranging from -10 °C to -40 °C, while the air was at room temperature. We observed that the freeze front moved very slowly up the bubble, and in some cases, even came to a complete halt at a critical height. This slow freezing front propagation can be explained by the low thermal conductivity of the thin soap film, and can be observed more clearly when the bubble size or the surface temperature is increased. This delayed freezing allows the frozen portion of the bubble to cool the air within the bubble while the top part is still liquid, which induces a vapor pressure mismatch that either collapses the top or causes the top to pop. In cases where the freeze front reaches the top of the bubble, a portion of the top may melt and slowly refreeze; this can happen more than just once for a single bubble. We also investigated freezing bubbles inside of a freezer where the air was held at -20 °C. In this case, the bubbles freeze quickly and the ice grows radially from nucleation sites instead of perpendicular to the surface, which provides a clear contrast with the conduction limited room temperature bubbles.

Solidification of salt solutions on a horizontal surface

International Nuclear Information System (INIS)

Braga, S.L.; Viskanta, R.

1990-01-01

The freezing of water-salt solutions on a horizontal wall is investigated experimentally and theoretically. The growth of the solid-liquid region is observed for NaCl - H sub(2)O and N H sub(4)Cl - H sub(2)O systems under different temperature and concentration conditions. A unidirectional mathematical model is used to predict the solidification process. The transport of heat is by diffusion, and convection is absent. The mass diffusion is neglected and the growth of crystal is governed by the transport of heat. In all experiments, the solution salt concentration is smaller than the eutectic composition, and the wall temperature is higher than the eutectic temperature. The predicted temperature and salt concentration profiles, as well as the interface position, are compared with experimental data. (author)

The preferential orientation and lattice misfit of the directionally solidified Fe-Al-Ta eutectic composite

Science.gov (United States)

Cui, Chunjuan; Wang, Pei; Yang, Meng; Wen, Yagang; Ren, Chiqiang; Wang, Songyuan

2018-01-01

Fe-Al intermetallic compound has been paid more attentions recently in many fields such as aeronautic, aerospace, automobile, energy and chemical engineering, and so on. In this paper Fe-Al-Ta eutectic was prepared by a modified Bridgman directional solidification technique, and it is found that microstructure of the Fe-Al-Ta eutectic alloy transforms from the broken-lamellar eutectic to cellular eutectic with the increase of the solidification rate. In the cellular eutectic structure, the fibers are parallel to each other within the same grain, but some fibers are deviated from the original orientation at the grain boundaries. To study the crystallographic orientation relationship (OR) between the two phases, the preferential orientation of the Fe-Al-Ta eutectic alloy at the different solidification rates was studied by Selected Area Electron Diffraction (SAED). Moreover, the lattice misfit between Fe2Ta(Al) Laves phase and Fe(Al,Ta) matrix phase was calculated.

Microstructural and mechanical properties of binary Ni–Si eutectic alloys

Energy Technology Data Exchange (ETDEWEB)

Gogebakan, Musa, E-mail: gogebakan@ksu.edu.tr [Department of Physics, Faculty of Art and Sciences, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100 (Turkey); Kursun, Celal [Department of Physics, Faculty of Art and Sciences, Kahramanmaras Sutcu Imam University, Kahramanmaras 46100 (Turkey); Gunduz, Kerem Ozgur; Tarakci, Mehmet; Gencer, Yucel [Department of Materials Science and Engineering, Gebze Institute of Technology, Gebze, 41400 Kocaeli (Turkey)

2015-09-15

Highlights: • Ni{sub 80}Si{sub 20}, Ni{sub 70}Si{sub 30}, Ni{sub 55}Si{sub 45} and Ni{sub 45}Si{sub 55} were prepared by arc melting method. • The maximum microhardness value of 1126 HV obtained for Ni{sub 70}Si{sub 30} alloy. • The microhardness values decreases with increase of Si/Ni ratio. • Ni{sub 80}Si{sub 20} and Ni{sub 55}Si{sub 45} are soft ferromagnetic, Ni{sub 70}Si{sub 30} and Ni{sub 45}Si{sub 55} are paramagnetic. - Abstract: In the present work, Ni–Si eutectic alloys with nominal compositions of Ni{sub 80}Si{sub 20}, Ni{sub 70}Si{sub 30}, Ni{sub 55}Si{sub 45} and Ni{sub 45}Si{sub 55} (Ni and Si with the purity of 99.99%) were prepared by arc melting method under vacuum/argon atmosphere. The effects of Si/Ni ratio on the microstructural properties, thermal transformation behavior, micro-hardness and magnetic properties of the Ni–Si eutectic alloys were investigated. These alloys were characterized by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM), differential thermal analysis (DTA), Vickers microhardness measurement and Vibrating Sample Magnetometer (VSM). The phases expected according to Ni–Si phase diagram for conventional solidified eutectic Ni–Si alloys are considerably consistent with phase detected by XRD in this study. The quantitative results confirm that the chemical composition of the alloys very close to eutectic compositions and the microstructures are in typical lamellar eutectic morphology. The maximum microhardness value of 1126 HV obtained for Ni{sub 70}Si{sub 30} alloy which has highest melting temperature amongst Ni–Si eutectics. The microhardness values decreases with increase of Si/Ni ratio. Ni{sub 80}Si{sub 20} and Ni{sub 55}Si{sub 45} alloys are soft ferromagnetic, Ni{sub 70}Si{sub 30} and Ni{sub 45}Si{sub 55} alloys are paramagnetic with no magnetic saturation.

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

Science.gov (United States)

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 same method with SAF, application of artificial supercooling accelerated the phase transition (traverse from -0.6℃ to -5℃) from 3.07 h (SAF) to 2.23 h (SSF). The observation of a microstructure indicated that the SSF prevented tissue damage caused by ice crystallization and maintained the structural integrity. The estimated quality parameters reflected that SSF exhibited superior meat quality compared with slow freezing (SAF). SSF showed better water-holding capacity (lower thawing loss, cooking loss and expressible moisture) and tenderness than SAF, and these quality parameters of SSF were not significantly different with ultra-fast freezing treatment (EIF). Consequently, the results demonstrated that the generation of supercooling followed by conventional freezing potentially had the advantage of minimizing the quality deterioration caused by the slow freezing of meat. PMID:27857541

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

Science.gov (United States)

Kim, Yiseul; Hong, Geun-Pyo

2016-10-31

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 same method with SAF, application of artificial supercooling accelerated the phase transition (traverse from -0.6℃ to -5℃) from 3.07 h (SAF) to 2.23 h (SSF). The observation of a microstructure indicated that the SSF prevented tissue damage caused by ice crystallization and maintained the structural integrity. The estimated quality parameters reflected that SSF exhibited superior meat quality compared with slow freezing (SAF). SSF showed better water-holding capacity (lower thawing loss, cooking loss and expressible moisture) and tenderness than SAF, and these quality parameters of SSF were not significantly different with ultra-fast freezing treatment (EIF). Consequently, the results demonstrated that the generation of supercooling followed by conventional freezing potentially had the advantage of minimizing the quality deterioration caused by the slow freezing of meat.

The principles of ultrasound and its application in freezing related processes of food materials: A review.

Science.gov (United States)

Cheng, Xinfeng; Zhang, Min; Xu, Baoguo; Adhikari, Benu; Sun, Jincai

2015-11-01

Ultrasonic processing is a novel and promising technology in food industry. The propagation of ultrasound in a medium generates various physical and chemical effects and these effects have been harnessed to improve the efficiency of various food processing operations. Ultrasound has also been used in food quality control as diagnostic technology. This article provides an overview of recent developments related to the application of ultrasound in low temperature and closely related processes such as freezing, thawing, freeze concentration and freeze drying. The applications of high intensity ultrasound to improve the efficiency of freezing process, to control the size and size distribution of ice crystals and to improve the quality of frozen foods have been discussed in considerable detail. The use of low intensity ultrasound in monitoring the ice content and to monitor the progress of freezing process has also been highlighted. Copyright © 2015 Elsevier B.V. All rights reserved.

Crystallization in Pd40Ni40P20 glass

DEFF Research Database (Denmark)

Jiang, Jianzhong; Saksl, K.; Nishiyama, N.

2002-01-01

Phase segregation and the effect of pressure on crystallization of bulk and ribbon Pd40Ni40P20 glasses have been studied by means of differential scanning calorimetry (DSC) and x-ray diffraction. The DSC measurements show only one glass transition event in the samples annealed at different...... temperatures in the supercooled liquid region. Phase analyses reveal at least five crystalline phases crystallized from the glass: monoclinic; body-centered tetragonal; orthorhombic; Ni2Pd2P and fcc-(Ni,Pd) solid solution phases. In the pressure range from 0 to 4.2 GPa, the crystallization temperature...... increases with pressure having a slope of 11 K/GPa. The eutectic crystallization reaction mode and crystalline phases formed are unchanged in the pressure range used. The enhancement of the crystallization temperature with increasing pressure in the glass can be explained by the suppression of atomic...

Crystal phase evolution of TiO2 nanoparticles with reaction time in acidic solutions studied via freeze-drying method

International Nuclear Information System (INIS)

Shin, Hyunho; Jung, Hyun Suk; Hong, Kug Sun; Lee, Jung-Kun

2005-01-01

The crystal phase evolution of TiO 2 nanoparticles, during hydrolysis and condensation of titanium tetraisopropoxide, was quenched at various reaction times by a freeze-drying method, followed by various characterizations. Three types of solutions with different acid input times were studied: (1) addition in infinite time (no addition) (2) addition at 24h after the hydrolysis/condensation reaction started, and (3) addition from the beginning of the reaction. The acid-free solution yielded amorphous TiO 2 , which transformed to anatase very slowly. The acid input in 24h resulted in a fast transformation of amorphous to a metastable anatase having a highly distorted atomic arrangement: thereby its transformation to a more stable phase, rutile, was suitable. The acid addition from the beginning of the reaction yielded the formation of a relatively stable anatase from the hydrolysis seed, thereby the subsequent transformation to rutile was sluggish

Behavior of radioisotope in liquid neutron irradiated Pb-17Li eutectic

International Nuclear Information System (INIS)

Tebus, V.N.; Aksenov, B.S.; Klabukov, U.G.

1994-01-01

Investigation of radioisotope 210 Po evaporation from liquid neutron irradiated Pb- 17 Li eutectic has been performed by Knudsen method. Equilibrium 210 Po vapor pressures at temperatures 250-700 degrees C were found about 3-4 orders of magnitude less than that for pure Po and were closed to equilibrium vapor pressures of Po-Pb compound. It was proposed Po forms stable Po-Pb compounds in eutectic at temperatures up to 750-800 degrees C. But disintegrates during long storage owing to self irradiation. It was determined Po aerosol transfer with radio gases takes place at the melting period. Contamination is happened also under irradiated eutectic storage at room temperature owing to aggregate recoil characteristic of Po

Monte Carlo simulation of the OCP freezing transition

International Nuclear Information System (INIS)

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

1992-09-01

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

Effect of the Cu and Ni content on the crystallization temperature and crystallization mechanism of La–Al–Cu(Ni metallic glasses

Directory of Open Access Journals (Sweden)

Peiyou Li

2016-02-01

Full Text Available The effect of the Cu and Ni content on the crystallization mechanism and the crystallization temperatures of La–Al–Cu(Ni metallic glasses (MGs was studied by differential scanning calorimetry (DSC. The experimental results have shown that the DSC curves obtained for the La–Al–Cu and La–Al–Ni MGs exhibit two and three crystallization temperatures, respectively. The crystallization temperatures of the La–Al–Cu and La–Al–Ni MGs result from the merging and splitting of thermal events related to the corresponding eutectic atomic pairs in the La72Cu28 and La81.6Al18.4 MGs, and La72Ni28 and La81.6Al18.4 MGs, respectively. In addition, Al- and Ni-containing clusters with weak or strong atomic interaction in the Al–Ni atomic pairs strongly affect the crystallization mechanism and thus the crystallization temperature of La–Al–Ni MGs. This study provides a novel understanding of the relation between the crystallization temperature and the underlying crystallization mechanisms in La–Al–Cu(Ni MGs.

Thermodynamic and morphological analysis of eutectic formation of CBZ-L-Asp and L-PheOMe.HCl mixtures

International Nuclear Information System (INIS)

Kim, Hyun Jung; Kim, Jong Hoon; Youn, Sung Hun; Shin, Chul Soo

2006-01-01

The eutectic melting of a CBZ-L-Asp/L-PheOMe.HCl model mixture was investigated in kinetic, thermal, thermodynamic, rheological, and morphological aspects. From TX-phase diagrams, the eutectic composition was determined to be 0.55 M fraction of CBZ-L-Asp. The highest melting rate and the lowest apparent viscosity in the range of 55-75 deg. C were obtained at the eutectic composition. Using Arrhenius plots of melting rates and apparent viscosities, minimum activation energies in the range of 60-80 deg. C were obtained at the eutectic composition, whereas maximum values were attained below 60 deg. C. At the eutectic composition, the maximum heat of fusion, the lowest excess free energy, and the highest excess entropy values were observed by differential scanning calorimetry (DSC). A highly homogeneous morphology due to rearrangement of molecules was observed in the eutectic mixture via scanning electron microscopy and X-ray diffraction analysis. IR spectra revealed that hydrogen bonding in the mixture increases during eutectic melting

Prospects for designing structural cast eutectic alloys on Al-Ce-Ni system base

International Nuclear Information System (INIS)

Belov, N.A.; Naumova, E.S.

1996-01-01

The phase diagram of Al-Ce-Ni system is built for an aluminium corner at component concentration up to 16 mass %Ce and 8 mass%Ni. A ternary eutectic reaction is established at 12%Ce, 5%Ni and 626 deg C. The ternary eutectic alloy is similar in structure to rapidly cooled Al base alloys with transition metals. The possibility to design new cast alloys based on three-phase (Al)+NiAl 3 +CeAl 4 eutectics is under consideration. Al-Zn-Mg-Cu, Al-Sc and Al-Zr base alloys can be used as (Al) constituent of the eutectics. The new alloys may be considered as heat resistant ones due to the fact that no structural changes are observed in castings on heating up to 350 deg C. 18 refs.; 4 figs.; 2 tabs

Effect of repeated freezing-thawing on the Achilles tendon of rabbits.

Science.gov (United States)

Chen, Lianxu; Wu, Yanping; Yu, Jiakuo; Jiao, Zhaode; Ao, Yingfang; Yu, Changlong; Wang, Jianquan; Cui, Guoqing

2011-06-01

The increased use of allograft tissue in the reconstruction of anterior cruciate ligament has brought more focus to the effect of storage and treatment on allograft. The purpose of this study was to observe the effect of histology and biomechanics on Achilles tendon in rabbits through repeated freezing-thawing before allograft tendon transplantation. Rabbit Achilles tendons were harvested and processed according to the manufacture's protocol of tissue bank, and freezing-thawing was repeated three times (group 1) and ten times (group 2). Those received only one cycle were used as controls. Then, tendons in each group were selected randomly to make for histological observations and biomechanics test. Histological observation showed that the following changes happened as the number of freezing-thawing increased: the arrangement of tendon bundles and collagen fibrils became disordered until ruptured, cells disrupted and apparent gaps appeared between tendon bundle because the formation of ice crystals. There were significant differences between the experimental and control groups in the values of maximum load, energy of maximum load and maximum stress, whereas no significant differences existed in other values such as stiffness, maximum strain, elastic modulus, and energy density. Therefore, repeated freezing-thawing had histological and biomechanical effect on Achilles tendon in rabbits before allograft tendon transplantation. This indicates that cautions should be taken in the repeated freezing-thawing preparation of allograft tendons in clinical application.

Accelerated redox reaction between chromate and phenolic pollutants during freezing

Energy Technology Data Exchange (ETDEWEB)

Ju, Jinjung; Kim, Jaesung [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of); Vetráková, Ľubica [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Seo, Jiwon [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Heger, Dominik [Department of Chemistry and Research Centre for Toxic Compounds in the Environment (RECETOX), Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno (Czech Republic); Lee, Changha [School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919 (Korea, Republic of); Yoon, Ho-Il [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Kitae, E-mail: ktkim@kopri.re.kr [Korea Polar Research Institute (KOPRI), Incheon 21990 (Korea, Republic of); Kim, Jungwon, E-mail: jwk@hallym.ac.kr [Department of Environmental Sciences and Biotechnology, Hallym University, Chuncheon, Gangwon-do 24252 (Korea, Republic of)

2017-05-05

Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

Accelerated redox reaction between chromate and phenolic pollutants during freezing

International Nuclear Information System (INIS)

Ju, Jinjung; Kim, Jaesung; Vetráková, Ľubica; Seo, Jiwon; Heger, Dominik; Lee, Changha; Yoon, Ho-Il; Kim, Kitae; Kim, Jungwon

2017-01-01

Highlights: • Redox conversion of 4-CP/Cr(VI) was significantly accelerated during freezing. • Accelerated redox conversion in ice is ascribed to the freeze concentration effect. • 4-CP, Cr(VI), and protons are concentrated in the liquid brine by freezing. • Redox conversions of various phenolic pollutants/Cr(VI) were significant in ice. • Freezing-accelerated redox conversion was observed in real polluted water. - Abstract: The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at −20 °C) was compared with the corresponding reaction in water (i.e., at 25 °C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV–vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions.

Exploring orange peel treatment with deep eutectic solvents and diluted organic acids

NARCIS (Netherlands)

van den Bruinhorst, A.; Kouris, P.; Timmer, J.M.K.; de Croon, M.H.J.M.; Kroon, M.C.

2016-01-01

The disintegration of orange peel waste in deep eutectic solvents and diluted organic acids is presented in this work. The albedo and flavedo layers of the peel were studied separately, showing faster disintegration of the latter. Addition of water to the deep eutectic solvents lowered the amount of

Technology for Obtaining Large Size Complex Oxide Crystals for Experiments on Muon-Electron Conversion Registration in High Energy Physics

Directory of Open Access Journals (Sweden)

Gerasymov, Ya.

2014-11-01

Full Text Available Technological approaches for qualitative large size scintillation crystals growing based on rare-earth silicates are proposed. A method of iridium crucibles charging using eutectic phase instead of a oxyorthosilicate was developed.

Interest and difficulties of O-g studies of the mechanisms of eutectic growth

International Nuclear Information System (INIS)

Lemaignan, Clement; Malmejac, Yves.

1976-01-01

The possible modifications of the very diverse mechanisms involved in a typical eutectic solidification due to the effects of O-g conditions are described. The convection effects, eutectic solidification, nucleation and relations between interlamellar spacing and growth rate are studied [fr

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

OpenAIRE

Singha, Poonam; Muthukumarappan, Kasiviswanathan

2015-01-01

Abstract Effects of different freezing rates and four different thawing methods on chemical composition, microstructure, and color of ginger were investigated. Computer simulation for predicting the freezing time of cylindrical ginger for two different freezing methods (slow and fast) was done using ANSYS ? Multiphysics. Different freezing rates (slow and fast) and thawing methods significantly (P?

Dynamical magnetic properties of the spin ice crystal Dy2Ti2O7

International Nuclear Information System (INIS)

Shi Jing; Tang, Z.; Zhu, B.P.; Huang, P.; Yin, D.; Li, C.Z.; Wang, Y.; Wen, H.

2007-01-01

The measurements of AC susceptibility between 2 and 40 K from zero field to 4 T both along the (0 0 1) and (1 1 1) axis in single-crystal Dy 2 Ti 2 O 7 show that the spin freezing along the (1 1 1) axis has stronger frequency dependence and magnetic field dependence, and the starting freezing frequency of the single crystal is higher than that of the polycrystalline sample

Algorithm of calculation of multicomponent system eutectics using electronic digital computer

International Nuclear Information System (INIS)

Posypajko, V.I.; Stratilatov, B.V.; Pervikova, V.I.; Volkov, V.Ya.

1975-01-01

A computer algorithm is proposed for determining low-temperature equilibrium regions for existing phases. The algorithm has been used in calculating nonvariant parameters (temperatures of melting of eutectics and the concentrations of their components) for a series of trinary systems, among which are Ksub(long)Cl, WO 4 , SO 4 (x 1 =K 2 WO 4 ; x 2 =K 2 SO 4 ), Ag, Cd, Pbsub(long)Cl(x 1 =CdCl 2 , x 2 =PbCl 2 ); Ksub(long)F, Cl, I (x 1 =KF, x 2 =KI). The proposed method of calculating eutectics permits the planning of the subsequent experiment in determining the parameters of the eutectics of multicomponent systems and the forecasting of chemical interaction in such systems. The algorithm can be used in calculating systems containing any number of components

Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

International Nuclear Information System (INIS)

Knowlton, W.B.; Lawrence Berkeley Lab., CA

1995-07-01

This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 angstrom Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 angstrom, 500 angstrom, and 300 angstrom per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 angstrom/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 angstrom/side appear to correspond with the phonon transmission study

Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces

Energy Technology Data Exchange (ETDEWEB)

Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

1995-07-01

This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.

Eutectic cell and nodule count as the quality factors of cast iron

Directory of Open Access Journals (Sweden)

E. Fraś

2008-10-01

Full Text Available In this work the predictions based on a theoretical analysis aimed at elucidating of eutectic cell count or nodule counts N wereexperimentally verified. The experimental work was focused on processing flake graphite and ductile iron under various inoculationconditions in order to achieve various physicochemical states of the experimental melts. In addition, plates of various wall thicknesses, s were cast and the resultant eutectic cell or nodule counts were established. Moreover, thermal analysis was used to find out the degree of maximum undercooling for the graphite eutectic, Tm. A relationship was found between the eutectic cell or nodule count and the maximum undercooling Tm.. In addition it was also found that N can be related to the wall thickness of plate shaped castings. Finally, the present work provides a rational for the effect of technological factors such as the melt chemistry, inoculation practice, and holding temperature and time on the resultant cell count or nodule count of cast iron. In particular, good agreement was found between the predictions of the theoretical analysis and the experimental data.

Freeze drying method

International Nuclear Information System (INIS)

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

1999-01-01

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

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

Science.gov (United States)

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

2015-06-01

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

Eutectic reaction analysis between TRU-50%Zr alloy fuel and HT-9 cladding, and temperature prediction of eutectic reaction under steady-state

Energy Technology Data Exchange (ETDEWEB)

Hwang, Woan; Lee, Byoung Oon; Lee, Bong Sang; Park, Won Seok

2001-02-01

Blanket fuel assembly for HYPER contains a bundle of pins arrayed in triangular pitch, which has hexagonal bundle structure. The reference blanket fuel pin consists of the fuel slug of TRU-50wt%Zr alloy and the cladding material of ferritic martensite steel, HT-9. Chemical interaction between fuel slug and cladding is one of the major concerns in metallic fuel rod design. The contact of metallic fuel slug and stainless steel cladding in a fuel rod forms a complex multi-component diffusion couple at elevated temperatures. The potential problem of inter-diffusion of fuel and cladding components is essentially two-fold weakening of cladding mechanical strength due to the formation of diffusion zones in the cladding, and the formation of comparatively low melting point phases in the fuel/cladding interface to develop eutectic reaction. The main components of fuel slug are composed of zirconium alloying element in plutonium matrix, including neptunium, americium and uranium additionally. Therefore basic eutectic reaction change of Pu-Fe binary system can be assessed, while it is estimated how much other elements zirconium, uranium, americium and neptunium influence on plutonium phase stability. Afterwards it is needed that eutectic reaction is verified through experimental necessarily.

Eutectic reaction analysis between TRU-50%Zr alloy fuel and HT-9 cladding, and temperature prediction of eutectic reaction under steady-state

International Nuclear Information System (INIS)

Hwang, Woan; Lee, Byoung Oon; Lee, Bong Sang; Park, Won Seok

2001-02-01

Blanket fuel assembly for HYPER contains a bundle of pins arrayed in triangular pitch, which has hexagonal bundle structure. The reference blanket fuel pin consists of the fuel slug of TRU-50wt%Zr alloy and the cladding material of ferritic martensite steel, HT-9. Chemical interaction between fuel slug and cladding is one of the major concerns in metallic fuel rod design. The contact of metallic fuel slug and stainless steel cladding in a fuel rod forms a complex multi-component diffusion couple at elevated temperatures. The potential problem of inter-diffusion of fuel and cladding components is essentially two-fold weakening of cladding mechanical strength due to the formation of diffusion zones in the cladding, and the formation of comparatively low melting point phases in the fuel/cladding interface to develop eutectic reaction. The main components of fuel slug are composed of zirconium alloying element in plutonium matrix, including neptunium, americium and uranium additionally. Therefore basic eutectic reaction change of Pu-Fe binary system can be assessed, while it is estimated how much other elements zirconium, uranium, americium and neptunium influence on plutonium phase stability. Afterwards it is needed that eutectic reaction is verified through experimental necessarily

Data supporting the prediction of the properties of eutectic organic phase change materials

Directory of Open Access Journals (Sweden)

Samer Kahwaji

2018-04-01

Full Text Available The data presented in this article include the molar masses, melting temperatures, latent heats of fusion and temperature-dependent heat capacities of fifteen fatty acid phase change materials (PCMs. The data are used in conjunction with the thermodynamic models discussed in Kahwaji and White (2018 [1] to develop a computational tool that calculates the eutectic compositions and thermal properties of eutectic mixtures of PCMs. The computational tool is part of this article and consists of a Microsoft Excel® file available in Mendeley Data repository [2]. A description of the computational tool along with the properties of nearly 100 binary mixtures of fatty acid PCMs calculated using this tool are also included in the present article. The Excel® file is designed such that it can be easily modified or expanded by users to calculate the properties of eutectic mixtures of other classes of PCMs. Keywords: Phase change materials, PCM, Eutectic, Thermal properties, Thermal energy storage

Structure of liquid Au-Si alloys around the eutectic region

Energy Technology Data Exchange (ETDEWEB)

Takeda, S. [Faculty of Sciences, Kyushu University, Ropponmatsu Fukuoka 810-8560 (Japan)], E-Mail: takeda@rc.kyushu-u.ac.jp; Fujii, H. [Graduate School of Sciences, Kyushu University, Ropponmatsu Fukuoka 810-8560 (Japan); Kawakita, Y. [Faculty of Sciences, Kyushu University, Ropponmatsu Fukuoka 810-8560 (Japan); Kato, Y. [Graduate School of Sciences, Kyushu University, Ropponmatsu Fukuoka 810-8560 (Japan); Fujita, S. [Graduate School of Sciences, Kyushu University, Ropponmatsu Fukuoka 810-8560 (Japan); Yokota, Y. [Graduate School of Sciences, Kyushu University, Ropponmatsu Fukuoka 810-8560 (Japan); Kohara, S. [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouo Mikazuki-cho, Sayou-gun Hyogo 670-5198 (Japan)

2007-03-25

X-ray diffraction measurements have been carried out for liquid Au-Si alloys around the eutectic region by the transmission method using high-energy X-ray to investigate the atomic arrangements in the liquid state. From the temperature dependence of the observed structure factors, the partial pair correlation and the detailed atomic arrangements will be discussed on the basis of a Reverse Monte Carlo analysis. The reproduced atomic arrangements around the eutectic region suggest the substitution structure and also rather dense liquid with decreasing temperature.

High ice nucleation activity located in blueberry stem bark is linked to primary freeze initiation and adaptive freezing behaviour of the bark

Science.gov (United States)

Kishimoto, Tadashi; Yamazaki, Hideyuki; Saruwatari, Atsushi; Murakawa, Hiroki; Sekozawa, Yoshihiko; Kuchitsu, Kazuyuki; Price, William S.; Ishikawa, Masaya

2014-01-01

Controlled ice nucleation is an important mechanism in cold-hardy plant tissues for avoiding excessive supercooling of the protoplasm, for inducing extracellular freezing and/or for accommodating ice crystals in specific tissues. To understand its nature, it is necessary to characterize the ice nucleation activity (INA), defined as the ability of a tissue to induce heterogeneous ice nucleation. Few studies have addressed the precise localization of INA in wintering plant tissues in respect of its function. For this purpose, we recently revised a test tube INA assay and examined INA in various tissues of over 600 species. Extremely high levels of INA (−1 to −4 °C) in two wintering blueberry cultivars of contrasting freezing tolerance were found. Their INA was much greater than in other cold-hardy species and was found to be evenly distributed along the stems of the current year's growth. Concentrations of active ice nuclei in the stem were estimated from quantitative analyses. Stem INA was localized mainly in the bark while the xylem and pith had much lower INA. Bark INA was located mostly in the cell wall fraction (cell walls and intercellular structural components). Intracellular fractions had much less INA. Some cultivar differences were identified. The results corresponded closely with the intrinsic freezing behaviour (extracellular freezing) of the bark, icicle accumulation in the bark and initial ice nucleation in the stem under dry surface conditions. Stem INA was resistant to various antimicrobial treatments. These properties and specific localization imply that high INA in blueberry stems is of intrinsic origin and contributes to the spontaneous initiation of freezing in extracellular spaces of the bark by acting as a subfreezing temperature sensor. PMID:25082142

Compatibility of amino acids in ice Ih and high-pressure phases: implications for the origin of life

Science.gov (United States)

Hao, J.; Giovenco, E.; Pedreira-Segade, U.; Montagnac, G.; Daniel, I.

2017-12-01

Icy environments may have been common on the early Earth due to the faint young sun. Previous studies have proposed that the formation of large icy bodies in the early ocean could concentrate the building blocks of life in eutectic fluids and therefore facilitate the polymerization of monomers. This hypothesis is based on the untested assumption that organic molecules are virtually incompatible in ice Ih. In this study, we conducted freezing experiments to explore the partitioning behavior of selected amino acids (glycine, L-alanine, L-proline, and L-phenylalanine) between ice Ih and aqueous solutions analogous to seawater. We let ice crystals grow slowly from a few seeds in equilibrium with the solution and used Raman spectroscopy to analyze in situ the relative concentrations of amino acids in the ice and aqueous solution. During freezing, there was no precipitation of amino acid crystals, indicating that the concentrations in solution never reached their solubility limit, even when the droplet was mostly frozen. Analyses of the Raman spectra of ice and eutectic solution showed that considerable amounts of amino acids existed in the ice phase with partition coefficients ranging between 0.2 and 0.5. This study also explored the partitioning of amino acids between other phases of ice (ice VI and ice VII) and solutions at high pressures and observed similar results. These observations implied little incompatibility of amino acids in ice during the freezing of the solutions, rendering the hypothesis of a cold origin of life unwarranted. However, incorporation into ice could significantly improve the efficiency of extraterrestrial transport of small organics. Therefore, this study supports the hypothesis of extraterrestrial delivery of organic molecules in the icy comets and asteroids to the primitive Earth as suggested by an increasing number of independent observations.

Growth and solid/solid transformation in a Ni-Si eutectic alloy

Energy Technology Data Exchange (ETDEWEB)

Dutra, A.T. [Department of Materials Engineering, State University of Campinas, P.O. Box 6122, Campinas 13083-970, SP (Brazil); Ferrandini, P.L. [Department of Materials Engineering, State University of Campinas, P.O. Box 6122, Campinas 13083-970, SP (Brazil); Costa, C.A.R. [Institute of Chemistry, State University of Campinas, P.O. Box 6154, Campinas 13083-970, SP (Brazil); Goncalves, M.C. [Institute of Chemistry, State University of Campinas, P.O. Box 6154, Campinas 13083-970, SP (Brazil); Caram, R. [Department of Materials Engineering, State University of Campinas, P.O. Box 6122, Campinas 13083-970, SP (Brazil)]. E-mail: rcaram@fem.unicamp.br

2005-08-16

High temperature structural components demand materials that maintain satisfactory mechanical and chemical characteristics. These needs may be met by applying some eutectic alloys, including Ni-Ni{sub 3}Si. This paper deals with the directional solidification of Ni-Ni{sub 3}Si grown under several growth rates. The analysis of the eutectic microstructure was carried out using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The results obtained provided a precise analysis of the Ni{sub 3}Si phase. It could be noticed that the solid/solid transformations by which Ni{sub 3}Si phase goes through, deeply affects its morphology. In addition, quantitative information on the eutectic structure was obtained. It was confirmed that the growth rate variation deeply affects the final microstructure as it influences the efficiency of atomic diffusion along the solid/liquid interface.

Growth and solid/solid transformation in a Ni-Si eutectic alloy

International Nuclear Information System (INIS)

Dutra, A.T.; Ferrandini, P.L.; Costa, C.A.R.; Goncalves, M.C.; Caram, R.

2005-01-01

High temperature structural components demand materials that maintain satisfactory mechanical and chemical characteristics. These needs may be met by applying some eutectic alloys, including Ni-Ni 3 Si. This paper deals with the directional solidification of Ni-Ni 3 Si grown under several growth rates. The analysis of the eutectic microstructure was carried out using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The results obtained provided a precise analysis of the Ni 3 Si phase. It could be noticed that the solid/solid transformations by which Ni 3 Si phase goes through, deeply affects its morphology. In addition, quantitative information on the eutectic structure was obtained. It was confirmed that the growth rate variation deeply affects the final microstructure as it influences the efficiency of atomic diffusion along the solid/liquid interface

Molecular interactions in the betaine monohydrate-polyol deep eutectic solvents: Experimental and computational studies

Science.gov (United States)

Zahrina, Ida; Mulia, Kamarza; Yanuar, Arry; Nasikin, Mohammad

2018-04-01

DES (deep eutectic solvents) are a new class of ionic liquids that have excellent properties. The strength of interaction between molecules in the DES affects their properties and applications. In this work, the strength of molecular interactions between components in the betaine monohydrate salt and polyol (glycerol or/and propylene glycol) eutectic mixtures was studied by experimental and computational studies. The melting point and fusion enthalpy of the mixtures were measured using STA (Simultaneous Thermal Analyzer). The nature and strength of intermolecular interactions were observed by FT-IR and NMR spectroscopy. The molecular dynamics simulation was used to determine the number of H-bonds, percent occupancy, and radial distribution functions in the eutectic mixtures. The interaction between betaine monohydrate and polyol is following order: betaine monohydrate-glycerol-propylene glycol > betaine monohydrate-glycerol > betaine monohydrate-propylene glycol, where the latter is the eutectic mixture with the lowest stability, strength and extent of the hydrogen bonding interactions between component molecules. The presence of intra-molecular hydrogen bonding interactions, the inter-molecular hydrogen bonding interactions between betaine molecule and polyol, and also interactions between polyol and H2O of betaine monohydrate in the eutectic mixtures.

Vacancies in quantal Wigner crystals near melting

International Nuclear Information System (INIS)

Barraza, N.; Colletti, L.; Tosi, M.P.

1999-04-01

We estimate the formation energy of lattice vacancies in quantal Wigner crystals of charged particles near their melting point at zero temperature, in terms of the crystalline Lindemann parameter and of the static dielectric function of the fluid phase near freezing. For both 3D and 2D crystals of electrons our results suggest the presence of vacancies in the ground state at the melting density. (author)

Solidification with back-diffusion of irregular eutectics

Directory of Open Access Journals (Sweden)

M. Trepczyńska-Łent

2008-10-01

Full Text Available The definition of the α - parameter back-diffusion has been introduced in the work. The alternative models of solidification were describedtaking into consideration back-diffusion process. The possibility of using those models for eutectic alloys solidification is worthyof interest.

Superchilling of muscle foods: Potential alternative for chilling and freezing.

Science.gov (United States)

Banerjee, Rituparna; Maheswarappa, Naveena Basappa

2017-12-05

Superchilling is an attractive technique for preservation of muscle foods which freezes part of the water and insulate the food products from temperature fluctuations thereby enhancing the shelf-life during storage, transportation and retailing. Superchilling process synergistically improves the product shelf-life when used in combination with vacuum or modified atmospheric packaging. The shelf-life of muscle foods was reported to be increased by 1.5 to 4.0 times relative to traditional chilling technique. Advantages of superchilling and its ability to maintain the freshness of muscle foods over freezing has been discussed and its potential for Industrial application is highlighted. Present review also unravel the mechanistic bases for ice-crystal formation during superchilling and measures to ameliorate the drip loss. The future challenges especially automation in superchilling process for large scale Industrial application is presented.

Eutectic structures in friction spot welding joint of aluminum alloy to copper

International Nuclear Information System (INIS)

Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos

2014-01-01

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl 2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting

Freezing during tapping tasks in patients with advanced Parkinson's disease and freezing of gait.

Science.gov (United States)

Delval, Arnaud; Defebvre, Luc; Tard, Céline

2017-01-01

Parkinson's disease patients with freezing of gait also experience sudden motor blocks (freezing) during other repetitive motor tasks. We assessed the proportion of patients with advanced PD and freezing of gait who also displayed segmental "freezing" in tapping tasks. Fifteen Parkinson's disease patients with freezing of gait were assessed. Freezing of gait was evaluated using a standardized gait trajectory with the usual triggers. Patients performed repetitive tapping movements (as described in the MDS-UPDRS task) with the hands or the feet in the presence or absence of a metronome set to 4 Hz. Movements were recorded with a video motion system. The primary endpoint was the occurrence of segmental freezing in these tapping tasks. The secondary endpoints were (i) the relationship between segmental episodic phenomena and FoG severity, and (ii) the reliability of the measurements. For the upper limbs, freezing was observed more frequently with a metronome (21% of trials) than without a metronome (5%). For the lower limbs, the incidence of freezing was higher than for the upper limbs, and was again observed more frequently in the presence of an auditory cue (47%) than in its absence (14%). Although freezing of the lower limbs was easily assessed during an MDS-UPDRS task with a metronome, it was not correlated with the severity of freezing of gait (as evaluated during a standardized gait trajectory). Only this latter was a reliable measurement in patients with advanced Parkinson's disease.

Mechanisms of heterogeneous crystal growth in atomic systems: insights from computer simulations.

Science.gov (United States)

Gulam Razul, M S; Hendry, J G; Kusalik, P G

2005-11-22

In this paper we analyze the atomic-level structure of solid/liquid interfaces of Lennard-Jones fcc systems. The 001, 011, and 111 faces are examined during steady-state growth and melting of these crystals. The mechanisms of crystallization and melting are explored using averaged configurations generated during these steady-state runs, where subsequent tagging and labeling of particles at the interface provide many insights into the detailed atomic behavior at the freezing and melting interfaces. The interfaces are generally found to be rough and we observe the structure of freezing and melting interfaces to be very similar. Large structural fluctuations with solidlike and liquidlike characteristics are apparent in both the freezing and melting interfaces. The behavior at the interface observed under either growth or melting conditions reflects a competition between ordering and disordering processes. In addition, we observe atom hopping that imparts liquidlike characteristics to the solid side of the interfaces for all three crystal faces. Solid order is observed to extend as rough, three-dimensional protuberances through the interface, particularly for the 001 and 011 faces. We are also able to reconcile our different measures for the interfacial width and address the onset of asymmetry in the growth rates at high rates of crystal growth/melting.

Rare earth concentration in the primary Si crystal in rare earth added Al-21 wt. % Si alloy

Energy Technology Data Exchange (ETDEWEB)

Chang, J.Y.; Kim, G.H. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of); Moon, I.G.; Choi, C.S. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Metallurgical Engineering

1998-07-03

Al-Si alloys containing more than about 12 wt. % Si exhibit a hypereutectic microstructure, normally consisting of a primary silicon phase in an eutectic matrix. The primary silicon in normal hypereutectic alloys is usually very coarse and thus leads to poor properties to these alloys. Therefore, alloys with a predominantly coarse primary silicon crystal must be modified to ensure adequate mechanical strength and ductility. Further improvement of mechanical properties of these alloys can be achieved by the modification of eutectic microstructure. Therefore, development of a modifier or refiner that can produce both fine primary and eutectic Si is a major factor which can lead to significant enhancement of mechanical properties in hypereutectic Al-Si alloys. Refinement of primary silicon is usually achieved by the addition of phosphor to the melt. On the other hand, it is reported that the rare earth (RE) elements are capable of modifying the eutectic structure of cast Al-Si alloys. According to the literature, Phosphor acts as a heterogeneous nucleation site of Si crystal by forming AlP intermetallic particles at high temperature, i.e., above liquidus temperature of Al-Si alloy. Unlike phosphor, RE was not known to form a stable compound with Al that can act as a nucleation site at high temperature. Therefore, the role of RE as a refiner should be considered by examining the behavior of RE as a solute in the melt. The distribution of RE within the primary Si and in the matrix of the alloy will provide a clue to the role of RE on the modification of primary Si during solidification.

Well-plate freeze-drying

DEFF Research Database (Denmark)

Trnka, Hjalte; Rantanen, Jukka; Grohganz, Holger

2015-01-01

Abstract Context: Freeze-drying in presence of excipients is a common practice to stabilize biomacromolecular formulations. The composition of this formulation is known to affect the quality of the final product. Objective: The aim of this study was to evaluate freeze-drying in well-plates as a h......Abstract Context: Freeze-drying in presence of excipients is a common practice to stabilize biomacromolecular formulations. The composition of this formulation is known to affect the quality of the final product. Objective: The aim of this study was to evaluate freeze-drying in well......-plates as a high throughput platform for formulation screening of freeze-dried products. Methods: Model formulations consisting of mannitol, sucrose and bovine serum albumin were freeze-dried in brass well plates, plastic well plates and vials. Physical properties investigated were solid form, residual moisture......, 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...

Synthesis, crystal growth, structural and physicochemical studies of novel binary organic complex: 4-chloroaniline–3-hydroxy-4-methoxybenzaldehyde

International Nuclear Information System (INIS)

Sharma, K.P.; Reddi, R.S.B.; Bhattacharya, S.; Rai, R.N.

2012-01-01

The solid-state reaction, which is solvent free and green synthesis, has been adopted to explore the novel compound. The phase diagram of 4-chloroaniline (CA) and 3-hydroxy-4-methoxybenzaldehyde (HMB) system shows the formation of a novel 1:1 molecular complex, and two eutectics on either sides of complex. Thermochemical studies of complex and eutectics have been carried out for various properties such as heat of fusion, entropy of fusion, Jackson's parameters, interfacial energy and excess thermodynamic functions. The formation of molecular complex was also studied by IR, NMR, elemental analysis and UV–Vis absorption spectra. The single crystal of molecular complex was grown and its XRD study confirms the formation of complex and identifies the crystal structure and atomic packing of crystal of complex. Transmission spectra of grown crystal of the complex show 70% transmittance efficiency with cut off wavelength 412 nm. The band gap and refractive index of the crystal of complex have also been studied. - Graphical abstarct: Exploiting phase diagram study and solvent free synthesis a novel compound was synthesized and its single crystal growth, atomic packing, energy band gap and refractive index were studied. Highlights: ► Novel organic complex was synthesized using Green or solvent free synthesis. ► Phase diagram study provided the information to identify the worthy composition of novel complex. ► The single crystal of the sufficient size was grown from the ethanol solution. ► Crystal analysis suggested that the covalent bond is formed between the two parent compounds. ► The transmittance of the crystal was found to be 70% and it was transparent from 412 to 850 nm.

Stiff, porous scaffolds from magnetized alumina particles aligned by magnetic freeze casting.

Science.gov (United States)

Frank, Michael B; Naleway, Steven E; Haroush, Tsuk; Liu, Chin-Hung; Siu, Sze Hei; Ng, Jerry; Torres, Ivan; Ismail, Ali; Karandikar, Keyur; Porter, Michael M; Graeve, Olivia A; McKittrick, Joanna

2017-08-01

Bone consists of a hard mineral phase and a compliant biopolymer phase resulting in a composite material that is both lightweight and strong. Osteoporosis that degrades spongy bone preferentially over time leads to bone brittleness in the elderly. A porous ceramic material that can mimic spongy bone for a one-time implant provides a potential solution for the future needs of an aging population. Scaffolds made by magnetic freeze casting resemble the aligned porosity of spongy bone. A magnetic field applied throughout freezing induces particle chaining and alignment of lamellae structures between growing ice crystals. After freeze drying to extract the ice and sintering to strengthen the scaffold, cubes from the scaffold center are mechanically compressed along longitudinal (z-axis, ice growth direction) and transverse (y-axis, magnetic field direction) axes. The best alignment of lamellar walls in the scaffold center occurs when applying magnetic freeze casting with the largest particles (350nm) at an intermediate magnetic field strength (75mT), which also agrees with stiffness enhancement results in both z and y-axes. Magnetic moments of different sized magnetized alumina particles help determine the ideal magnetic field strength needed to induce alignment in the scaffold center rather than just at the poles. Copyright © 2017 Elsevier B.V. All rights reserved.

Five-dimensional imaging of freezing emulsions with solute effects.

Science.gov (United States)

Dedovets, Dmytro; Monteux, Cécile; Deville, Sylvain

2018-04-20

The interaction of objects with a moving solidification front is a common feature of many industrial and natural processes such as metal processing, the growth of single crystals, the cryopreservation of cells, or the formation of sea ice. Interaction of solidification fronts with objects leads to different outcomes, from total rejection of the objects to their complete engulfment. We imaged the freezing of emulsions in five dimensions (space, time, and solute concentration) with confocal microscopy. We showed that the solute induces long-range interactions that determine the solidification microstructure. The local increase of solute concentration enhances premelting, which controls the engulfment of droplets by the front and the evolution of grain boundaries. Freezing emulsions may be a good analog of many solidification systems where objects interact with a solidification interface. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Establishment of the Co-C Eutectic Fixed-Point Cell for Thermocouple Calibrations at NIMT

Science.gov (United States)

Ongrai, O.; Elliott, C. J.

2017-08-01

In 2015, NIMT first established a Co-C eutectic temperature reference (fixed-point) cell measurement capability for thermocouple calibration to support the requirements of Thailand's heavy industries and secondary laboratories. The Co-C eutectic fixed-point cell is a facility transferred from NPL, where the design was developed through European and UK national measurement system projects. In this paper, we describe the establishment of a Co-C eutectic fixed-point cell for thermocouple calibration at NIMT. This paper demonstrates achievement of the required furnace uniformity, the Co-C plateau realization and the comparison data between NIMT and NPL Co-C cells by using the same standard Pt/Pd thermocouple, demonstrating traceability. The NIMT measurement capability for noble metal type thermocouples at the new Co-C eutectic fixed point (1324.06°C) is estimated to be within ± 0.60 K (k=2). This meets the needs of Thailand's high-temperature thermocouple users—for which previously there has been no traceable calibration facility.

Into the depths of deep eutectic solvents

NARCIS (Netherlands)

Rodriguez, N.; Alves da Rocha, M.A.; Kroon, M.C.

2015-01-01

Ionic liquids (ILs) have been successfully tested in a wide range of applications; however, their high price and complicated synthesis make them infeasible for large scale implementation. A decade ago, a new generation of solvents so called deep eutectic solvents (DESs) was reported for the first

An Expeditious and Greener Synthesis of 2-Aminoimidazoles in Deep Eutectic Solvents

Directory of Open Access Journals (Sweden)

Martina Capua

2016-07-01

Full Text Available A high-yield one-pot two-step synthesis of 2-aminoimidazoles (2-AI, exploiting an under-air heterocyclodehydration process between α-chloroketones and guanidine derivatives, and using deep eutectic solvents (DESs as nonconventional, “green” and “innocent” reaction media, has been accomplished successfully. The combination of either glycerol or urea with choline chloride (ChCl proved to be effective for decreasing the reaction time to about 4–6 h in contrast to the 10–12 h usually required for the same reaction run in toxic and volatile organic solvents and under an argon atmosphere. In addition, the use of the ChCl–urea as a DES also enables the direct isolation of triaryl-substituted 2-AI derivatives by means of a simple work-up procedure consisting in filtration and crystallization, and allows the recycle of the DES mixture. A plausible mechanism highlighting the potential role played by hydrogen bonding catalysis has also been illustrated.

Microstructural evolution of ternary Ag33Cu42Ge25 eutectic alloy inside ultrasonic field

Directory of Open Access Journals (Sweden)

Wei Zhai

2014-12-01

Full Text Available Ultrasonic field with a frequency of 20 kHz is introduced into the solidification process of ternary Ag33Cu42Ge25 eutectic alloy from the sample bottom to its top. The ultrasound stimulates the nucleation of alloy melt and prevents its bulk undercooling. At low ultrasound power of 250 W, the primary ε2 phase in the whole alloy sample grows into non-faceted equiaxed grains, which differs to its faceted morphology of long strip under static condition. The pseudobinary (Ag+ε2 eutectic transits from dendrite shape grain composed of rod type eutectic to equiaxed chrysanthemus shape formed by lamellar structure. By contrast, the ultrasound produces no obvious variation in the morphology of ternary (Ag+Ge+ε2 eutectic except a coarsening effect. When ultrasound power rises to 500 W, divorced ternary (Ag+Ge+ε2 eutectic forms at the sample bottom. However, in the upper part, the ultrasonic energy weakens, and it only brings about prominent refining effect to primary ε2 phase. The microstructural evolution mechanism is investigated on the cavitation, acoustic streaming and acoustic attenuation.

A comparison of freezing-damage during isochoric and isobaric freezing of the potato

OpenAIRE

Lyu, Chenang; Nastase, Gabriel; Ukpai, Gideon; Serban, Alexandru; Rubinsky, Boris

2017-01-01

Background Freezing is commonly used for food preservation. It is usually done under constant atmospheric pressure (isobaric). While extending the life of the produce, isobaric freezing has detrimental effects. It causes loss of food weight and changes in food quality. Using thermodynamic analysis, we have developed a theoretical model of the process of freezing in a constant volume system (isochoric). The mathematical model suggests that the detrimental effects associated with isobaric freez...

Oxygen partial pressure: a key to alloying and discovery in metal oxide--metal eutectic systems

International Nuclear Information System (INIS)

Holder, J.D.; Clark, G.W.; Oliver, B.F.

1978-01-01

Control of oxygen partial pressure is essential in the directional solidification of oxide--metal eutectic composites by techniques involving gas-solid and gas-liquid interactions. The existence of end components in the eutectic composite is Po 2 sensitive as are melt stoichiometry, solid phase compositions, and vapor losses due to oxidation-volatilization. Simple criteria are postulated which can aid the experimentalist in selecting the proper gas mixture for oxide--metal eutectic composite growth. The Cr 2 O 3 --Mo--Cr systems was used to verify certain aspects of the proposed criteria

An Electrochemistry Study of Cryoelectrolysis in Frozen Physiological Saline.

Science.gov (United States)

Manuel, Thomas J; Munnangi, Pujita; Rubinsky, Boris

2017-07-01

Cryoelectrolysis is a new minimally invasive tissue ablation surgical technique that combines the processes of electrolysis and solid/liquid phase transformation (freezing). This study investigated this new technique by measuring the pH front propagation and the changes in resistance in a tissue simulant made of physiological saline gel with a pH dye as a function of the sample temperature in the high subzero range above the eutectic. Results demonstrated that effective electrolysis can occur in a high subzero freezing milieu and that the propagation of the pH front is only weakly dependent on temperature. These observations are consistent with a mechanism involving ionic movement through the concentrated saline solution channels between ice crystals at subfreezing temperatures above the eutectic. Moreover, results suggest that Joule heating in these microchannels may cause local microscopic melting, the observed weak dependence of pH front propagation on temperature, and the large changes in resistance with time. A final insight provided by the results is that the pH front propagation from the anode is more rapid than from the cathode, a feature indicative of the electro-osmotic flow from the cathode to the anode. The findings in this paper may be critical for designing future cryoelectrolytic ablation surgery protocols.

Thermodynamically controlled crystallization of glucose pentaacetates from amorphous phase

Energy Technology Data Exchange (ETDEWEB)

Wlodarczyk, P., E-mail: patrykw@imn.gliwice.pl; Hawelek, L.; Hudecki, A.; Kolano-Burian, A. [Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-100 Gliwice (Poland); Wlodarczyk, A. [Department of Animal Histology and Embryology, University of Silesia, ul. Bankowa 9, 40-007 Katowice (Poland)

2016-08-15

The α and β glucose pentaacetates are known sugar derivatives, which can be potentially used as stabilizers of amorphous phase of active ingredients of drugs (API). In the present work, crystallization behavior of equimolar mixture of α and β form in comparison to both pure anomers is revealed. It was shown that despite the same molecular interactions and similar molecular dynamics, crystallization from amorphous phase is significantly suppressed in equimolar mixture. Time dependent X-ray diffraction studies confirmed higher stability of the quenched amorphous equimolar mixture. Its tendency to crystallization is about 10 times lower than for pure anomers. Calorimetric studies revealed that the α and β anomers don’t form solid solutions and have eutectic point for x{sub α} = 0.625. Suppressed crystallization tendency in the mixture is probably caused by the altered thermodynamics of the system. The factors such as difference of free energy between crystalline and amorphous state or altered configurational entropy are probably responsible for the inhibitory effect.

Insertion of lead lithium eutectic mixture in RELAP/SCDAPSIM Mod 4.0 for Fusion Reactor Systems

International Nuclear Information System (INIS)

Tiwari, Ashutosh; Allison, Brian; Hohorst, J.K.; Wagner, R.J.; Allison, Chris

2012-01-01

Highlights: ► Thermodynamic and transport properties of lead lithium eutectic mixture have been inserted in RELAP/SCDAPSIM MOD 4.0 code. ► Code results are verified for a simple pipe problem with lead lithium eutectic mixture flowing in it. ► Code is calculating the inserted properties of lead lithium eutectic mixture to a fairly good agreement. - Abstract: RELAP/SCDAPSIM Mod 4.0 code was developed by Innovative System Software (ISS) for the analysis of nuclear power plants (NPPs) cooled by light water and heavy water. Later on the code was expanded to analyze the NPPs cooled by liquid metal, in this sequence: lead bismuth eutectic mixture, liquid sodium and lead lithium eutectic mixture (LLE) are inserted in the code. This paper focuses on the insertion of liquid LLE as a coolant for NPPs in the RELAP/SCDAPSIM Mod 4.0 code. Evaluation of the code was made for a simple pipe problem connected with heat structures having liquid LLE as a coolant in it. The code is predicting well all the thermodynamic and transport properties of LLE.

Effect of modified mold shell on the microstructure and tensile fracture morphology of single-crystal nickel-base superalloy

Science.gov (United States)

Xu, Weitai; Zhao, Yutao; Sun, Shaochun; Liu, Manping; Ma, Dexin; Liang, Xiangfeng; Wang, Cunlong; Tao, Ran

2018-04-01

The mold shell used for single-crystal turbine blades preparation was modified from conventional process to fiber reinforcement technology. The wall thickness was decreased by 32.3 percent (pct) than the conventional process. Then these two mold shells were used to produce single crystal samples of nickel-base superalloy in a Bridgman furnace. The local temperature curves were recorded in the process. The results show that the modified mold shell can increase the temperature gradient in the mushy zone than the conventional mold shell. The primary and secondary dendrite arm space were reduced by 8 pct and 12 pct, respectively. Moreover, both the area fraction and mean size of the γ‧/γ eutectic were declined, as well as the dendritic segregation tendency. Therefore it contributed to the lower residual eutectic and micro-porosity in the heat-treated microstructure. Further, fracture surface of the samples made by modified mold shell exhibited smaller facets and more uniform dimples in the size and shape.

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%.

Modeling of Eutectic Formation in Al-Si Alloy Using A Phase-Field Method

Directory of Open Access Journals (Sweden)

Ebrahimi Z.

2017-12-01

Full Text Available We have utilized a phase-field model to investigate the evolution of eutectic silicon in Al-Si alloy. The interfacial fluctuations are included into a phase-field model of two-phase solidification, as stochastic noise terms and their dominant role in eutectic silicon formation is discussed. We have observed that silicon spherical particles nucleate on the foundation of primary aluminum phase and their nucleation continues on concentric rings, through the Al matrix. The nucleation of silicon particles is attributed to the inclusion of fluctuations into the phase-field equations. The simulation results have shown needle-like, fish-bone like and flakes of silicon phase by adjusting the noise coefficients to larger values. Moreover, the role of primary Al phase on nucleation of silicon particles in Al-Si alloy is elaborated. We have found that the addition of fluctuations plays the role of modifiers in our simulations and is essential for phase-field modeling of eutectic growth in Al-Si system. The simulated finger-like Al phases and spherical Si particles are very similar to those of experimental eutectic growth in modified Al-Si alloy.

Phase Evolution in and Creep Properties of Nb-Rich Nb-Si-Cr Eutectics

Science.gov (United States)

Gang, Florian; Kauffmann, Alexander; Heilmaier, Martin

2018-03-01

In this work, the Nb-rich ternary eutectic in the Nb-Si-Cr system has been experimentally determined to be Nb-10.9Si-28.4Cr (in at. pct). The eutectic is composed of three main phases: Nb solid solution (Nbss), β-Cr2Nb, and Nb9(Si,Cr)5. The ternary eutectic microstructure remains stable for several hundred hours at a temperature up to 1473 K (1200 °C). At 1573 K (1300 °C) and above, the silicide phase Nb9(Si,Cr)5 decomposes into α-Nb5Si3, Nbss, and β-Cr2Nb. Under creep conditions at 1473 K (1200 °C), the alloy deforms by dislocation creep while the major creep resistance is provided by the silicide matrix. If the silicide phase is fragmented and, thus, its matrix character is destroyed by prior heat treatment [ e.g., at 1773 K (1500 °C) for 100 hours], creep is mainly controlled by the Laves phase β-Cr2Nb, resulting in increased minimum strain rates. Compared to state of the art Ni-based superalloys, the creep resistance of this three-phase eutectic alloy is significantly higher.

Microstructure of directionally solidified Ti-Fe eutectic alloy with low interstitial and high mechanical strength

Science.gov (United States)

Contieri, R. J.; Lopes, E. S. N.; Taquire de La Cruz, M.; Costa, A. M.; Afonso, C. R. M.; Caram, R.

2011-10-01

The performance of Ti alloys can be considerably enhanced by combining Ti and other elements, causing an eutectic transformation and thereby producing composites in situ from the liquid phase. This paper reports on the processing and characterization of a directionally solidified Ti-Fe eutectic alloy. Directional solidification at different growth rates was carried out in a setup that employs a water-cooled copper crucible combined with a voltaic electric arc moving through the sample. The results obtained show that a regular fiber-like eutectic structure was produced and the interphase spacing was found to be a function of the growth rate. Mechanical properties were measured using compression, microindentation and nanoindentation tests to determine the Vickers hardness, compressive strength and elastic modulus. Directionally solidified eutectic samples presented high values of compressive strength in the range of 1844-3000 MPa and ductility between 21.6 and 25.2%.

Purification of used eutectic (LiCl-KCl) salt electrolyte from pyroprocessing

Science.gov (United States)

Cho, Yung-Zun; Lee, Tae-Kyo; Eun, Hee-Chul; Choi, Jung-Hoon; Kim, In-Tae; Park, Geun-Il

2013-06-01

The separation characteristics of surrogate rare-earth fission products in a eutectic (LiCl-KCl) molten salt were investigated. This system is based on the eutectic salt used for the pyroprocessing treatment of used nuclear fuel (UNF). The investigation was performed using an integrated rare-earth separation apparatus comprising a precipitation reactor, a solid detachment device, and a layer separation device. To separate rare-earth fission products, a phosphate precipitation method using both Li3PO4 and K3PO4 as a precipitant was performed. The use of an equivalent phosphate precipitant composed of 0.408 molar ratio-K3PO4 and 0.592 molar ratio-Li3PO4 can preserve the original eutectic ratio, LiCl-0.592 molar ratio (or 45.2 wt%), as well as provide a high separation efficiency of over 99.5% under conditions of 550 °C and Ar sparging when using La, Nd, Ce, and Pr chlorides. The mixture of La, Nd, Ce, and Pr phosphate had a typical monoclinic (or monazite) structure, which has been proposed as a reliable host matrix for the permanent disposal of a high-level waste form. To maximize the reusability of purified eutectic waste salt after rare-earth separation, the successive rare-earth separation process, which uses both phosphate precipitation and an oxygen sparging method, were introduced and tested with eight rare-earth (Y, La, Ce, Pr, Nd, Sm, Eu and Gd) chlorides. In the successive rare-earth separation process, the phosphate reaction was terminated within 1 h at 550 °C, and a 4-8 h oxygen sparging time were required to obtain over a 99% separation efficiency at 700-750 °C. The mixture of rare-earth precipitates separated by the successive rare-earth separation process was found to be phosphate, oxychloride, and oxide. Through the successive rare-earth separation process, the eutectic ratio of purified salt maintained its original value, and impurity content including the residual precipitant of purified salt can be minimized.

Directional solidification of Al2-Cu-Al and Al3-Ni-Al eutectics during TEXUS rocket flight

Science.gov (United States)

Favier, J. J.; Degoer, J.

1984-01-01

One lamellar eutectic sample and one fiber-like eutectic sample were solidified directionally during the TEXUS-6 rocket flight. The microstructures and the results of the thermal analysis, obtained from the temperatures recorded on the cartridge skin, are compared. No appreciable modifications of the regularity of the eutectic structures were observed by passing from 1 g to 0.0001 g in these experiments. No steady state growth conditions were achieved in these experiments.

Synthesis, crystal growth, structural and physicochemical studies of novel binary organic complex: 4-chloroaniline-3-hydroxy-4-methoxybenzaldehyde

Energy Technology Data Exchange (ETDEWEB)

Sharma, K.P.; Reddi, R.S.B.; Bhattacharya, S. [Department of Chemistry, Centre of Advance Study, Banaras Hindu University, Varanasi-221005 (India); Rai, R.N., E-mail: rn_rai@yahoo.co.in [Department of Chemistry, Centre of Advance Study, Banaras Hindu University, Varanasi-221005 (India)

2012-06-15

The solid-state reaction, which is solvent free and green synthesis, has been adopted to explore the novel compound. The phase diagram of 4-chloroaniline (CA) and 3-hydroxy-4-methoxybenzaldehyde (HMB) system shows the formation of a novel 1:1 molecular complex, and two eutectics on either sides of complex. Thermochemical studies of complex and eutectics have been carried out for various properties such as heat of fusion, entropy of fusion, Jackson's parameters, interfacial energy and excess thermodynamic functions. The formation of molecular complex was also studied by IR, NMR, elemental analysis and UV-Vis absorption spectra. The single crystal of molecular complex was grown and its XRD study confirms the formation of complex and identifies the crystal structure and atomic packing of crystal of complex. Transmission spectra of grown crystal of the complex show 70% transmittance efficiency with cut off wavelength 412 nm. The band gap and refractive index of the crystal of complex have also been studied. - Graphical abstarct: Exploiting phase diagram study and solvent free synthesis a novel compound was synthesized and its single crystal growth, atomic packing, energy band gap and refractive index were studied. Highlights: Black-Right-Pointing-Pointer Novel organic complex was synthesized using Green or solvent free synthesis. Black-Right-Pointing-Pointer Phase diagram study provided the information to identify the worthy composition of novel complex. Black-Right-Pointing-Pointer The single crystal of the sufficient size was grown from the ethanol solution. Black-Right-Pointing-Pointer Crystal analysis suggested that the covalent bond is formed between the two parent compounds. Black-Right-Pointing-Pointer The transmittance of the crystal was found to be 70% and it was transparent from 412 to 850 nm.

Fabrication of the tetrathiafulvalene–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane charge transfer complex with high crystallinity by eutectic melting method

Science.gov (United States)

Kim, Jueun; Kang, Youngjong; Lee, Jaejong

2018-06-01

We show that high crystallinity and charge transporting gain can be obtained in a noble donor–acceptor system (CT complex) composed of organic complex: tetrathiafulvalene–2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TTF–F4TCNQ). The complex is small-gap organic metallic or semiconductor (less than 1 eV), and we predict having a high conductivity. We perform an approach to fabricate organic CT complex with high crystallinity by eutectic melting method. Our process is simple and shows crystal growth with improved crystallinity when combined with soft-lithography.

Experimental specifications for eutectic reaction between metallic fuel and HT-9

International Nuclear Information System (INIS)

Hwang, Woan; Nam, Cheol; Lee, Byoung Oon; Ryu, Woo Seog

1998-10-01

The chemical interaction between metallic fuel and cladding is important in designing the fuel pin of the KALIMER. When metal fuel and cladding are contacted, the elements in fuel and cladding are inter-diffuse each other, forming the reaction layers at interface. The reaction layers may cause two important factors in aspects of fuel pin integrity. Firstly, it degrades cladding strength by reducing effective cladding thickness. Secondly, these layers accelerate eutectic reaction at transient conditions. To evaluate these phenomena, the diffusion couple experiment is planned by using metal fuels with various zirconium contents and HT-9 steel. The U-Zr fuel alloys will be used for the experiment with the different zirconium contents, these are 8, 10 and 12 weight %. This experiment aims to evaluate the effects of zirconium content on the chemical reaction. Furthermore, the reaction rate and threshold temperature of the eutectic melting will be determined as a function of the zirconium content. This document describes the detail experimental specifications for the eutectic reaction such as test setup, test requirements and test procedure. (author). 10 refs

Accelerated redox reaction between chromate and phenolic pollutants during freezing.

Science.gov (United States)

Ju, Jinjung; Kim, Jaesung; Vetráková, Ľubica; Seo, Jiwon; Heger, Dominik; Lee, Changha; Yoon, Ho-Il; Kim, Kitae; Kim, Jungwon

2017-05-05

The redox reaction between 4-chlorophenol (4-CP) and chromate (Cr(VI)) (i.e., the simultaneous oxidation of 4-CP by Cr(VI) and reduction of Cr(VI) by 4-CP) in ice (i.e., at -20°C) was compared with the corresponding reaction in water (i.e., at 25°C). The redox conversion of 4-CP/Cr(VI), which was negligible in water, was significantly accelerated in ice. This accelerated redox conversion of 4-CP/Cr(VI) in ice is ascribed to the freeze concentration effect occurring during freezing, which excludes solutes (i.e., 4-CP and Cr(VI)) and protons from the ice crystals and subsequently concentrates them in the liquid brine. The concentrations of Cr(VI) and protons in the liquid brine were confirmed by measuring the optical image and the UV-vis absorption spectra of cresol red (CR) as a pH indicator of frozen solution. The redox conversion of 4-CP/Cr(VI) was observed in water when the concentrations of 4-CP/protons or Cr(VI)/protons increased by 100/1000-fold. These results corroborate the freeze concentration effect as the reason for the accelerated redox conversion of 4-CP/Cr(VI) in ice. The redox conversion of various phenolic pollutants/Cr(VI) and 4-CP/Cr(VI) in real wastewater was successfully achieved in ice, which verifies the environmental relevance and importance of freezing-accelerated redox conversion of phenolic pollutants/Cr(VI) in cold regions. Copyright © 2017 Elsevier B.V. All rights reserved.

Versatile wedge-based system for the construction of unidirectional collagen scaffolds by directional freezing: practical and theoretical considerations

NARCIS (Netherlands)

Pot, M.W.; Faraj, K.A.; Adawy, A.; Enckevort, W.J.P. van; Moerkerk, H.T. van; Vlieg, E.; Daamen, W.F.; Kuppevelt, T.H. van

2015-01-01

Aligned unidirectional collagen scaffolds may aid regeneration of those tissues where alignment of cells and extracellular matrix is essential, as for instance in cartilage, nerve bundles, and skeletal muscle. Pores can be introduced by ice crystal formation followed by freeze-drying, the pore

Thermo-physical stability of fatty acid eutectic mixtures subjected to accelerated aging for thermal energy storage (TES) application

International Nuclear Information System (INIS)

Fauzi, Hadi; Metselaar, Hendrik S.C.; Mahlia, T.M.I.; Silakhori, Mahyar

2014-01-01

The thermo-physical stability of fatty acids eutectic mixtures subjected to accelerated number of melting/solidification processes has been identified using thermal cycling test in this study. Myristic acid/palmitic acid (MA/PA) (70/30, wt.%) and myristic acid/palmitic acid/sodium stearate (MA/PA/SS) (70/30/5, wt.%) were selected as eutectic phase change materials (PCMs) to evaluate their stability of phase transition temperature, latent heat of fusion, chemical structure, and volume changes after 200, 500, 1000, and 1500 thermal cycles. The thermal properties of each eutectic PCMs measured by differential scanning calorimetric (DSC) indicated the phase transition temperature and latent heat of fusion values of MA/PA/SS has a smallest changes after 1500 thermal cycles than MA/PA eutectic mixture. MA/PA/SS also has a better chemical structure stability and smaller volume change which is 1.2%, compared to MA/PA with a volume change of 1.6% after 1500 cycles. Therefore, it is concluded that the MA/PA/SS eutectic mixture is suitable for use as a phase change material in thermal energy storage (TES) such as solar water heating and solar space heating applications. - Highlights: •The prepared MA/PA and MA/PA/SS were used as eutectic phase change materials (PCM). •Thermo-physical reliability of eutectic PCMs evaluated using a thermal cycling test. •MA/PA/SS has a great thermo-physical stability than MA/PA after 1500 thermal cycles

Effects of Eutectic Si Particles on Mechanical Properties and Fracture Toughness of Cast A356 Aluminum Alloys

International Nuclear Information System (INIS)

Lee, Kyu Hong; Lee, Sung Hak; Kwon, Yong Nam

2007-01-01

The present study aims at investigating the effects of eutectic Si particles on mechanical properties and fracture toughness of three A356 aluminum alloys. These A356 alloys were fabricated by casting processes such as rheo-casting, squeeze-casting, and casting-forging, and their mechanical properties and fracture toughness were analyzed in relation with microfracture mechanism study. All the cast A356 alloys contained eutectic Si particles mainly segregated along solidification cells, and the distribution of Si particles was modified by squeeze-casting and casting-forging processes. Microfracture observation results showed that eutectic Si particles segregated along cells were cracked first, but that aluminum matrix played a role in blocking crack propagation. Tensile properties and fracture toughness of the squeeze cast and cast-forged alloys having homogeneous distribution of eutectic Si particles were superior to those of the rheo-cast alloy. In particular, the cast-forged alloy had excellent hardness, strength, ductility, and fracture toughness because of the matrix strengthening and homogeneous distribution of eutectic Si particles due to forging process

Development of salt hydrate eutectics as latent heat storage for air conditioning and cooling

International Nuclear Information System (INIS)

Efimova, Anastasia; Pinnau, Sebastian; Mischke, Matthias; Breitkopf, Cornelia; Ruck, Michael; Schmidt, Peer

2014-01-01

Graphical abstract: - Highlights: • Inorganic salt hydrates. • Latent heat thermal energy storage. • Thermal behavior of melting and crystallization. • Cycling stability. • Nucleation. - Abstract: Sustainable air conditioning systems require heat reservoirs that operate between 4 and 20 °C. A systematic search for binary and ternary eutectics of inorganic salts and salt hydrates with melting temperatures in this temperature regime and with high enthalpies of fusion has been performed by means of differential scanning calorimetry (DSC). Promising results were obtained for the pseudo-ternary system Zn(NO 3 ) 2 ·6H 2 O, Mn(NO 3 ) 2 ·4H 2 O, and KNO 3 with the melting temperature range 18–21 °C and the enthalpy of fusion of about 110 kJ kg −1 . Suitable nucleating and thickening agents have been found and tested to prevent the mixture from supercooling and phase separation

Sustainable Poly(Ionic Liquids) for CO2 Capture Based on Deep Eutectic Monomers

KAUST Repository

Isik, Mehmet; Zulfiqar, Sonia; Edhaim, Fatimah; Ruiperez, Fernando; Rothenberger, Alexander; Mecerreyes, David

2016-01-01

The design of high performance solid sorbent materials for CO2 capture is a technology which has been employed to mitigate global warming. However, the covalent incorporation of functionalities into polymeric supports usually involves multistep energy-intensive chemical processes. This fact makes the net CO2 balance of the materials negative even though they possess good properties as CO2 sorbents. Here we show a new family of polymers which are based on amines, amidoximes, and natural carboxylic acids and can be obtained using sustainable low energy processes. Thus, deep eutectic monomers based on natural carboxylic acids, amidoximes, and amines have been prepared by just mixing with cholinium type methacrylic ammonium monomer. The formation of deep eutectic monomers was confirmed by differential scanning calorimetry measurements. In all cases, the monomers displayed glass transition temperatures well below room temperature. Computational studies revealed that the formation of eutectic complexes lengthens the distance between the cation and the anion causing charge delocalization. The liquid nature of the resulting deep eutectic monomers (DEMs) made it possible to conduct a fast photopolymerization process to obtain the corresponding poly(ionic liquids). Materials were characterized by means of nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction to evaluate the properties of the polymers. The polymers were then used as solid sorbents for CO2 capture. It has been shown that the polymers prepared with citric acid displayed better performance both experimentally and computationally. The current endeavor showed that sustainable poly(ionic liquids) based on deep eutectic monomers can be easily prepared to produce low-energy-cost alternatives to the materials currently being researched for CO2 capture. © 2016 American Chemical Society.

Sustainable Poly(Ionic Liquids) for CO2 Capture Based on Deep Eutectic Monomers

KAUST Repository

Isik, Mehmet

2016-10-05

The design of high performance solid sorbent materials for CO2 capture is a technology which has been employed to mitigate global warming. However, the covalent incorporation of functionalities into polymeric supports usually involves multistep energy-intensive chemical processes. This fact makes the net CO2 balance of the materials negative even though they possess good properties as CO2 sorbents. Here we show a new family of polymers which are based on amines, amidoximes, and natural carboxylic acids and can be obtained using sustainable low energy processes. Thus, deep eutectic monomers based on natural carboxylic acids, amidoximes, and amines have been prepared by just mixing with cholinium type methacrylic ammonium monomer. The formation of deep eutectic monomers was confirmed by differential scanning calorimetry measurements. In all cases, the monomers displayed glass transition temperatures well below room temperature. Computational studies revealed that the formation of eutectic complexes lengthens the distance between the cation and the anion causing charge delocalization. The liquid nature of the resulting deep eutectic monomers (DEMs) made it possible to conduct a fast photopolymerization process to obtain the corresponding poly(ionic liquids). Materials were characterized by means of nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction to evaluate the properties of the polymers. The polymers were then used as solid sorbents for CO2 capture. It has been shown that the polymers prepared with citric acid displayed better performance both experimentally and computationally. The current endeavor showed that sustainable poly(ionic liquids) based on deep eutectic monomers can be easily prepared to produce low-energy-cost alternatives to the materials currently being researched for CO2 capture. © 2016 American Chemical Society.

Parametric Study for Devulcanization of Waste Tire Rubber Utilizing Deep Eutectic Solvent (DES

Directory of Open Access Journals (Sweden)

Walvekar Rashmi

2018-01-01

Full Text Available Waste rubber is a polymeric material containing 50% of rubber and is generally referred to as waste tyre rubber. The main purpose of this research is to study ultrasonic devulcanisation of waste rubber utilising deep eutectic solvent (DES of ZnCl2:Urea by improving process parameters such as sonication time, reaction temperature and rubber: DES mass ratio by effectively cleaving cross-link sulphur bonds. DES was created and prepared by mixing ZnCl2 with urea at 2:7 and 1:4 molar ratios respectively. Physicochemical properties of the prepared DES was measured using DSC, KFT and TGA analysis to find the freezing point, moisture content and degradation temperature, whereby their freezing point below 60°C, moisture content lower than 3.0 wt.% and 200°C degradation temperature average. Rubber to DES mass ratio was varied at 1:20, 1:30 and 1:40 and sonicated for 15 minutes inside ultrasonic water-bath. Samples were placed onto hot plate whereby heating temperature was varied at room temperature, 130°C, 150°C, and 180°C for 15 minutes. Samples were filtered, washed with distilled water and dried in oven for 24 hours. Once dried, samples were taken for analysis using TGA, EDX, FESEM, FTIR and Gel content. Under TGA analysis, most samples have an average degradation temperature of 200°C, hence justifying a successful devulcanisation. EDX analysis shows two occurrences during devulcanisation process which is bond reformation and cleavage. Furthermore, it is determined that heating temperature of 130°C is an important parameter as it is the optimum temperature for ZnCl2:Urea. Under FTIR analysis, it shows that disulphide bond, S-S is the only bond that is being broken while the rest still remains the same. Gel content analysis showed that samples have a lower soluble fraction after devulcanisation process. Finally, FESEM proves that at 130°C and 15 minutes is the optimum temperature and time which is illustrated by the smooth surface at that

Binary eutectic clusters and glass formation in ideal glass-forming liquids

International Nuclear Information System (INIS)

Lu, Z. P.; Shen, J.; Xing, D. W.; Sun, J. F.; Liu, C. T.

2006-01-01

In this letter, a physical concept of binary eutectic clusters in 'ideal' glass-forming liquids is proposed based on the characteristics of most well-known bulk metallic glasses (BMGs). The authors approach also includes the treatment of binary eutectic clusters as basic units, which leads to the development of a simple but reliable method for designing BMGs more efficiently and effectively in these unique glass-forming liquids. As an example, bulk glass formers with superior glass-forming ability in the Zr-Ni-Cu-Al and Zr-Fe-Cu-Al systems were identified with the use of the strategy

Investigation on cored-eutectic structure in Ni60/WC composite coatings fabricated by wide-band laser cladding

Energy Technology Data Exchange (ETDEWEB)

Ma, Qunshuang, E-mail: maqunshuang@126.com; Li, Yajiang, E-mail: yajli@sdu.edu.cn; Wang, Juan, E-mail: jwang@sdu.edu.cn; Liu, Kun, E-mail: liu_kun@163.com

2015-10-05

Highlights: • Perfect composite coatings were fabricated using wide-band laser cladding. • Special cored-eutectic structure was synthesized in Ni60/WC composite coatings. • Cored-eutectic consists of hard carbide compounds and fine lamellar eutectic of M{sub 23}C{sub 6} carbides and γ-Ni(Fe). • Wear resistance of coating layer was significantly improved due to precipitation of M{sub 23}C{sub 6} carbides. - Abstract: Ni60 composite coatings reinforced with WC particles were fabricated on the surface of Q550 steel using LDF4000-100 fiber laser device. The wide-band laser and circular beam laser used in laser cladding were obtained by optical lens. Microstructure, elemental distribution, phase constitution and wear properties of different composite coatings were investigated. The results showed that WC particles were partly dissolved under the effect of wide-band fiber laser irradiation. A special cored-eutectic structure was synthesized due to dissolution of WC particles. According to EDS and XRD results, the inside cores were confirmed as carbides of M{sub 23}C{sub 6} enriched in Cr, W and Fe. These complex carbides were primarily separated out in the molten metal when solidification started. Eutectic structure composed of M{sub 23}C{sub 6} carbides and γ-Ni(Fe) grew around carbides when cooling. Element content of Cr and W is lower at the bottom of cladding layer. In consequence, the eutectic structure formed in this region did not have inside carbides. The coatings made by circular laser beam were composed of dendritic matrix and interdendritic eutectic carbides, lacking of block carbides. Compared to coatings made by circular laser spot, the cored-eutectic structure formed in wide-band coatings had advantages of well-distribution and tight binding with matrix. The uniform power density and energy distribution and the weak liquid convection in molten pool lead to the unique microstructure evolution in composite coatings made by wide-band laser

Role of bismuth on solidification, microstructure and mechanical properties of a near eutectic Al-Si alloys

Science.gov (United States)

Farahany, Saeed; Ourdjini, Ali; Bakar, Tuty Asma Abu; Idris, Mohd Hasbullah

2014-09-01

Computer aided thermal analysis and microstructural observation showed that addition of bismuth (Bi) within the range of 0.25 and 2 wt% produced a greater effect on the Al-Si eutectic phase than on primary aluminium and Al2Cu phases. Results showed that with addition of 1 wt% Bi the eutectic silicon structure was refined from flake-like morphology into lamellar. Bi refines rather than modifies the Si structure and increases the Al-Si eutectic fraction solid and more significantly there was no fading even up to 180 min of melt holding. Transmission electron microscopy study showed that the Si twin spacing decreased from 160 to 75 nm which is likely attributed to the refining effect of Bi. It was also found that addition of 1 wt% Bi increased the tensile strength, elongation and the absorbed energy for fracture due to the refined eutectic silicon structure.

Hydrophobic deep eutectic solvents as water-immiscible extractants

NARCIS (Netherlands)

Osch, van D.J.G.P.; Zubeir, L.F.; Bruinhorst, van den A.; Alves da Rocha, M.A.; Kroon, M.C.

2015-01-01

Hydrophobic deep eutectic solvents (DESs) are presented for the first time. They consist of decanoic acid and various quaternary ammonium salts. The effect of the alkyl chains on the hydrophobicity and the equilibrium of the two-phase DES–water system were investigated. These new DESs were

The immersion freezing behavior of size-segregated soot and kaolinite particles

Science.gov (United States)

Hartmann, S.; Augustin, S.; Clauss, T.; Niedermeier, D.; Raddatz, M.; Wex, H.; Shaw, R. A.; Stratmann, F.

2011-12-01

Heterogeneous ice nucleation plays a crucial role for ice formation in mixed-phase and cirrus clouds and has an important impact on precipitation formation, global radiation balances, and therefore Earth's climate (Cantrell and Heymsfield, 2005). Mineral dust and soot particles are found to be a major component of ice crystal residues (e.g., Pratt et al., 2009) so these substances are potential sources of atmospheric ice nuclei (IN). Experimental studies investigating the immersion freezing behavior of size-segregated soot and kaolinite particles conducted at the Leipzig Aerosol Cloud Interaction Simulator (LACIS) are presented. In our measurements only one aerosol particle is immersed in an air suspended water droplet which can trigger ice nucleation. The method facilitates very precise examinations with respect to temperature, ice nucleation time and ice nucleus size. Considering laboratory studies, the picture of the IN ability of soot particles is quite heterogeneous. Our studies show that submicron flame, spark soot particles and optionally coated with sulfuric acid to simulate chemically aging do not act as IN at temperatures higher than homogeneous freezing taking place. Therefore soot particles might not be an important source of IN for immersion freezing in the atmosphere. In contrast, kaolinite being representative for natural mineral dust with a well known composition and structure is found to be very active in forming ice for all freezing modes (e.g., Mason and Maybank, 1958). Analyzing the immersion freezing behavior of different sized kaolinite particles (300, 500 and 700 nm in diameter) the size effect was clearly observed, i.e. the ice fraction (number of frozen droplets per total number) scales with particle surface, i.e. the larger the ice nucleus surface the higher the ice fraction. The slope of the logarithm of the ice fraction as function of temperature is similar for all particle sizes investigated and fits very well with the results of L�

Crystallization, microstructure and mechanical properties of silumins with micro-additions of Cr, Mo, W and V

Directory of Open Access Journals (Sweden)

S. Pietrowski

2010-01-01

Full Text Available In this paper results of the crystallization, microstructure and mechanical properties studies of hypo-, hyper- and eutectic silumins with addition of: Cr, Mo, W and V in amount of about 0,05% are presented. The influence of Sb, Sr and P together with Ti + B on the silumins crystallization process has been given. Results of: the microstructure, Rm, Rp0,2, A5 and HB testing of silumins after precipitation hardening and heat treatment in temperature of 560°C/3min and water chilling are presented.

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.

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

Science.gov (United States)

Kim, Edward; Wu, Albert; DeMarco, Eugenia; Powers, Jarrett; Berg, Aaron; Rowlandson, Tracy; Freeman, Jacqueline; Gottfried, Kurt; Toose, Peter; Roy, Alexandre;

Deep Eutectic Solvents Enable More Robust Chemoenzymatic Epoxidation Reactions

NARCIS (Netherlands)

Zhou, Pengfei; Wang, Xuping; Zeng, Chaoxi; Wang, Weifei; Yang, Bo; Hollmann, F.; Wang, Yonghua

2017-01-01

A chemoenzymatic method for the production of epoxidized vegetable oils was developed. The unique combination of the commercial lipase G from Penicillieum camembertii with certain deep eutectic solvents enabled the efficient production of epoxidized vegetable oils.

Data supporting the prediction of the properties of eutectic organic phase change materials.

Science.gov (United States)

Kahwaji, Samer; White, Mary Anne

2018-04-01

The data presented in this article include the molar masses, melting temperatures, latent heats of fusion and temperature-dependent heat capacities of fifteen fatty acid phase change materials (PCMs). The data are used in conjunction with the thermodynamic models discussed in Kahwaji and White (2018) [1] to develop a computational tool that calculates the eutectic compositions and thermal properties of eutectic mixtures of PCMs. The computational tool is part of this article and consists of a Microsoft Excel® file available in Mendeley Data repository [2]. A description of the computational tool along with the properties of nearly 100 binary mixtures of fatty acid PCMs calculated using this tool are also included in the present article. The Excel® file is designed such that it can be easily modified or expanded by users to calculate the properties of eutectic mixtures of other classes of PCMs.

Effects of various freezing containers for vitrification freezing on mouse oogenesis.

Science.gov (United States)

Kim, Ji Chul; Kim, Jae Myeoung; Seo, Byoung Boo

2016-01-01

In the present study, various freezing containers were tested for mouse embryos of respective developmental stages; embryos were vitrified and then their survival rate and developmental rate were monitored. Mouse two cell, 8 cell, and blastula stage embryos underwent vitrification freezing-thawing and then their recovery rate, survival rate, development rate, and hatching rate were investigated. EM-grid, OPS, and cryo-loop were utilized for vitrification freezing-thawing of mouse embryos. It was found that recovery rate and survival rate were higher in the group of cryo-loop compared to those of EM-grid (p containers on vitrified embryos of respective developmental stages; it was demonstrated that higher developmental rate was shown in more progressed (or developed) embryos with more blastomeres. There was however, no difference in embryonic development rate was shown amongst containers. Taken together, further additional studies are warranted with regards to 1) manipulation techniques of embryos for various vitrification freezing containers and 2) preventive measures against contamination via liquid nitrogen.

Effect of scandium on structure and hardening of Al–Ca eutectic alloys

Energy Technology Data Exchange (ETDEWEB)

Belov, N.A., E-mail: nikolay-belov@yandex.ru [National Research and Technological University “MISIS”, 4, Leninsky pr., Moscow 119049 (Russian Federation); Naumova, E.A. [Bauman Moscow State Technical University, 5, 2 ul. Baumanskaya, Moscow, 105005 (Russian Federation); Alabin, A.N. [National Research and Technological University “MISIS”, 4, Leninsky pr., Moscow 119049 (Russian Federation); UC RUSAL, 13/1, Nikoloyamskaya st., Moscow, 109240 (Russian Federation); Matveeva, I.A. [UC RUSAL, 13/1, Nikoloyamskaya st., Moscow, 109240 (Russian Federation)

2015-10-15

The phase composition, structure and hardening of alloys in the aluminium corner of the Al–Ca–Sc system were studied in the range up to 10% Ca and up to 1% S≿. The experimental study (optical, scanning and transmission electron microscopy with electron-microprobe analysis, differential thermal analysis and hardness measurements) was combined with Thermo-Calc software simulation for the optimization of the alloy composition. It was shown that only phases of the binary systems (Al{sub 4}Ca and Al{sub 3}Sc) might be in equilibrium with the aluminium solid solution. It was shown that the (Al) + Al{sub 4}Ca eutectic had a much finer structure as compared with the Al–Si eutectic, which suggests a possibility of reaching higher mechanical properties as compared to commercial alloys of the A356 type. The influence of the annealing temperature within the range up to 600 °C on the structure and hardness of the Al–Ca–Sc experimental alloys was studied. It was determined that the maximum hardening corresponded to the annealing at 300 °C, which was due to the precipitation of Al{sub 3}Sc nanoparticles with their further coarsening. With an example of an Al-7.6% Ca-0.3% Sc model experimental alloy, a principal possibility of manufacturing aluminium casting alloys based on the (Al) + Al{sub 4}Ca eutectic was demonstrated. Unlike commercial alloys of the A356 type, the model alloy does not require quenching, as hardening particles are formed in the course of annealing of casting. - Highlights: • Al–Ca–Sc phase diagram in aluminum corner. • Formation of Al{sub 3}Sc nanoparticles in eutectic (Al) + Al{sub 4}Ca during heating at 300–450 °C. • Hardening and thermal stability of proposed (Al–Ca–Sc) and commercial (Al–Si–Mg, 356 type) eutectic alloys.

X-ray microanalysis of freeze-dried and frozen-hydrated cryosections

International Nuclear Information System (INIS)

Zierold, K.

1988-01-01

The elemental composition and the ultrastructure of biological cells were studied by scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray microanalysis. The preparation technique involves cryofixation, cryoultramicrotomy, cryotransfer, and freeze-drying of samples. Freeze-dried cryosections 100-nm thick appeared to be appropriate for measuring the distribution of diffusible elements and water in different compartments of the cells. The lateral analytical resolution was less than 50 nm, depending on ice crystal damage and section thickness. The detection limit was in the range of 10 mmol/kg dry weight for all elements with an atomic number higher than 12; for sodium and magnesium the detection limits were about 30 and 20 mmol/kg dry weight, respectively. The darkfield intensity in STEM is linearly related to the mass thickness. Thus, it becomes possible to measure the water content in intracellular compartments by using the darkfield signal of the dry mass remaining after freeze-drying. By combining the X-ray microanalytical data expressed as dry weight concentrations with the measurements of the water content, physiologically more meaningful wet weight concentrations of elements were determined. In comparison to freeze-dried cryosections frozen-hydrated sections showed poor contrast and were very sensitive against radiation damage, resulting in mass loss. The high electron exposure required for recording X-ray spectra made reproducible microanalysis of ultrathin (about 100-nm thick) frozen-hydrated sections impossible. The mass loss could be reduced by carbon coating; however, the improvement achieved thus far is still insufficient for applications in X-ray microanalysis. Therefore, at present only bulk specimens or at least 1-micron thick sections can be used for X-ray microanalysis of frozen-hydrated biological samples

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

International Nuclear Information System (INIS)

Ralfs, Julie D.

2002-01-01

Tissue porosity and fluid flow have been shown to be important parameters affecting the mechanical and sensorial behaviour of edible plant tissues. The quantity of fluid and the manner with which it was released on compression of the plant tissue were also important regarding the sensory perception and a good indication of any structural damage resulting from freezing, for example. Potato, carrot and Chinese water chestnut were used to study the effects freezing has on model plant tissues. Mechanical and structural measurements of the plant tissue were correlated with sensory analysis. Conventional freezing was shown to cause severe structural damage predominantly in the form of cavities between or through cells, resulting in decreases in mechanical strength and stiffness, and samples that were perceived in the mouth as 'soft' and 'wet'. The location and size of the cavities formed from ice crystals, depended on the particular plant tissue being frozen, the processing it was subjected to prior to freezing, the size of the sample and the cooling regime employed to freeze the tissue. Cavitation in the tissue resulted in an increase in tissue porosity, which enabled fluid to flow more easily from the tissue on compression, thus affecting the mechanical properties and sensory perception. Freezing damage to plant tissues was shown to be reduced, and sometimes prevented, when active antifreeze proteins (AFPs) were introduced into the tissues by vacuum infiltration or transformation and the tissue was frozen at a suitable cooling rate. Theoretical modelling was applied to the fluid flow and porosity data to test the validity of the models and to subsequently predict the mechanical behaviour of potato from the structural properties of the tissue. (author)

The value of a freeze

International Nuclear Information System (INIS)

Bethe, H.A.; Long, F.A.

1988-01-01

This paper reports on the rapid increase in public support for a nuclear-freeze agreement---that is, a mutual freeze on the testing, production and further deployment of nuclear weapons---which has been a remarkable political phenomenon. In less than a year, support has grown from a few volunteers collecting signatures on petitions to a congressional vote in which supporters of a freeze very nearly prevailed. This fall, eight states and the District of Columbia will vote on freeze referendums. Already Wisconsin voters have overwhelmingly voted yes in such a referendum. There are many reasons for this strong support for a freeze, including fear of nuclear war, resistance to high levels of military spending and opposition to particular military policies of the Reagan administration. But to most supporters, the chief purpose of a freeze is simple: it is to help stop an immense, continuing, dangerous and incredibly costly arms race between the two superpowers

Length-scale dependent mechanical properties of Al-Cu eutectic alloy: Molecular dynamics based model and its experimental verification

Science.gov (United States)

Tiwary, C. S.; Chakraborty, S.; Mahapatra, D. R.; Chattopadhyay, K.

2014-05-01

This paper attempts to gain an understanding of the effect of lamellar length scale on the mechanical properties of two-phase metal-intermetallic eutectic structure. We first develop a molecular dynamics model for the in-situ grown eutectic interface followed by a model of deformation of Al-Al2Cu lamellar eutectic. Leveraging the insights obtained from the simulation on the behaviour of dislocations at different length scales of the eutectic, we present and explain the experimental results on Al-Al2Cu eutectic with various different lamellar spacing. The physics behind the mechanism is further quantified with help of atomic level energy model for different length scale as well as different strain. An atomic level energy partitioning of the lamellae and the interface regions reveals that the energy of the lamellae core are accumulated more due to dislocations irrespective of the length-scale. Whereas the energy of the interface is accumulated more due to dislocations when the length-scale is smaller, but the trend is reversed when the length-scale is large beyond a critical size of about 80 nm.

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.

The Freezing Bomb

Science.gov (United States)

Mills, Allan

2010-01-01

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

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

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...

Deep eutectic solvents as performance additives in biphasic reactions

NARCIS (Netherlands)

Lan, Dongming; Wang, Xuping; Zhou, Pengfei; Hollmann, F.; Wang, Yonghua

2017-01-01

Deep eutectic solvents act as surfactants in biphasic (hydrophobic/aqueous) reaction mixtures enabling higher interfacial surface areas at lower mechanical stress as compared to simple emulsions. Exploiting this effect the rate of a chemoenzymatic epoxidation reaction was increased more than

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...... suggest that the process which takes place within the leather during the freeze-drying in not actual freeze-drying, but rather a sophisticated way of distributing the impregnating agent. The pure ice phase freezes out, but the impregnating agent remains liquid as the temperature does not become low enough...

Building the Method to Determine the Rate of Freezing Water in Penaeus monodon of the Freezing Process

OpenAIRE

Nguyen Tan Dzung; Trinh Van Dzung; Tran Duc Ba

2012-01-01

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 fre...

Development of salt hydrate eutectics as latent heat storage for air conditioning and cooling

Energy Technology Data Exchange (ETDEWEB)

Efimova, Anastasia [Brandenburgische Technische Universität (BTU) Cottbus – Senftenberg, Chair of Inorganic Chemistry, Großenhainer Str. 57, 01968 Senftenberg (Germany); Pinnau, Sebastian; Mischke, Matthias; Breitkopf, Cornelia [Technische Universität Dresden, Chair of Technical Thermodynamics, Helmholtzstr. 14, 01069 Dresden (Germany); Ruck, Michael [Technische Universität Dresden, Chair of Inorganic Chemistry, Bergstr. 66, 01062 Dresden (Germany); Schmidt, Peer, E-mail: peer.schmidt@hs-lausitz.de [Brandenburgische Technische Universität (BTU) Cottbus – Senftenberg, Chair of Inorganic Chemistry, Großenhainer Str. 57, 01968 Senftenberg (Germany)

2014-01-10

Graphical abstract: - Highlights: • Inorganic salt hydrates. • Latent heat thermal energy storage. • Thermal behavior of melting and crystallization. • Cycling stability. • Nucleation. - Abstract: Sustainable air conditioning systems require heat reservoirs that operate between 4 and 20 °C. A systematic search for binary and ternary eutectics of inorganic salts and salt hydrates with melting temperatures in this temperature regime and with high enthalpies of fusion has been performed by means of differential scanning calorimetry (DSC). Promising results were obtained for the pseudo-ternary system Zn(NO{sub 3}){sub 2}·6H{sub 2}O, Mn(NO{sub 3}){sub 2}·4H{sub 2}O, and KNO{sub 3} with the melting temperature range 18–21 °C and the enthalpy of fusion of about 110 kJ kg{sup −1}. Suitable nucleating and thickening agents have been found and tested to prevent the mixture from supercooling and phase separation.

Advantages of liquid nitrogen freezing of Penaeus monodon over conventional plate freezing

OpenAIRE

Chakrabarti, R.; Chaudhury, D.R.

1987-01-01

Liquid nitrogen frozen products are biochemically and organoleptically superior to conventional plate frozen products but beneficial effect of liquid nitrogen freezing over conventional plate freezing can exist only up to 59 days at a commercial storage temperature of -18°C.

Polymerization with freezing

International Nuclear Information System (INIS)

Ben-Naim, E; Krapivsky, P L

2005-01-01

Irreversible aggregation processes involving reactive and frozen clusters are investigated using the rate equation approach. In aggregation events, two clusters join irreversibly to form a larger cluster; additionally, reactive clusters may spontaneously freeze. Frozen clusters do not participate in merger events. Generally, freezing controls the nature of the aggregation process, as demonstrated by the final distribution of frozen clusters. The cluster mass distribution has a power-law tail, F k ∼k -γ , when the freezing process is sufficiently slow. Different exponents, γ = 1 and 3, are found for the constant and the product aggregation rates, respectively. For the latter case, the standard polymerization model, either no gels, or a single gel, or even multiple gels, may be produced

Formation of Al2O3-HfO2 Eutectic EBC Film on Silicon Carbide Substrate

Directory of Open Access Journals (Sweden)

Kyosuke Seya

2015-01-01

Full Text Available The formation mechanism of Al2O3-HfO2 eutectic structure, the preparation method, and the formation mechanism of the eutectic EBC layer on the silicon carbide substrate are summarized. Al2O3-HfO2 eutectic EBC film is prepared by optical zone melting method on the silicon carbide substrate. At high temperature, a small amount of silicon carbide decomposed into silicon and carbon. The components of Al2O3 and HfO2 in molten phase also react with the free carbon. The Al2O3 phase reacts with free carbon and vapor species of AlO phase is formed. The composition of the molten phase becomes HfO2 rich from the eutectic composition. HfO2 phase also reacts with the free carbon and HfC phase is formed on the silicon carbide substrate; then a high density intermediate layer is formed. The adhesion between the intermediate layer and the substrate is excellent by an anchor effect. When the solidification process finished before all of HfO2 phase is reduced to HfC phase, HfC-HfO2 functionally graded layer is formed on the silicon carbide substrate and the Al2O3-HfO2 eutectic structure grows from the top of the intermediate layer.

Generalized structural theory of freezing

International Nuclear Information System (INIS)

Yussouff, M.

1980-10-01

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

Tuning the sapphire EFG process to the growth of Al2O3/YAG/ZrO2:Y eutectic

Science.gov (United States)

Carroz, L.; Duffar, T.

2018-05-01

In this work, a model is proposed, in order to analytically study the working point of the Edge defined Film-fed Growth (EFG) pulling of crystal plates. The model takes into account the heat equilibrium at the interface and the pressure equilibrium across the meniscus. It is validated on an industrial device dedicated to the pulling of sapphire ribbons. Then, the model is applied to pulling ceramic alloy plates, of the ternary eutectic Al2O3/YAG/ZrO2:Y. This allowed understanding the experimental difficulties of pulling this new material and suggested improvements of the control software. From these results, pulling net shaped ceramic alloy plates was successful in the same industrial equipment as used for sapphire.

The effect of the solidification mode on eutectic structure in Fe-C-V alloys

International Nuclear Information System (INIS)

Fras, E.; Guzik, E.

1980-01-01

The aim of the study was to determine such a chemical composition of Fe-C-V alloys which would ensure the formation of perfectly eutectic structures as well as to investigate the eutectic morphology of these alloys when undergoing bulk and directional solidification. Attempts have been done to get in situ composites from Fe-C-V alloys. The adopted testing methods as well as obtained results are described in detail. (H.M.)

Repeated freeze-thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons.

Science.gov (United States)

Suto, Kaori; Urabe, Ken; Naruse, Kouji; Uchida, Kentaro; Matsuura, Terumasa; Mikuni-Takagaki, Yuko; Suto, Mitsutoshi; Nemoto, Noriko; Kamiya, Kentaro; Itoman, Moritoshi

2012-03-01

Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze-thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze-thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze-thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze-thaw cycles. In patella tendons, the ultimate stress, Young's modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze-thaw cycles. In conclusion, we identified that cells surviving after freeze-thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze-thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

Anhydrobiosis and Freezing-Tolerance

DEFF Research Database (Denmark)

McGill, Lorraine; Shannon, Adam; Pisani, Davide

2015-01-01

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

Metal-ion catalyzed polymerization in the eutectic phase in water-ice

DEFF Research Database (Denmark)

Monnard, Pierre-Alain; Szostak, Jack W.

2008-01-01

The emergence of an RNA world requires among other processes the non-enzymatic, template-directed replication of genetic polymers such as RNA or related nucleic acids, possibly catalyzed by metal ions. The absence of uridilate derivative polymerization on adenine containing templates has been...... the main issue preventing an efficient template-directed RNA polymerization. We report here the investigation of template-directed RNA polymerization in the eutectic phase in water-ice. In particular, it was found that activated Uridilate monomers in the presence of metal-ion catalysts could efficiently......-pairing opportunities. These results suggest that a template-directed RNA polymerization catalyzed by metal-ions could be carried out under eutectic phase in water-ice conditions....

Ultrasonic absorption and velocity dispersion of binary mixture liquid crystal MBBA/EBBA

International Nuclear Information System (INIS)

Choi, K.

1979-01-01

The effect of phase transitions and the partial magnetic alignment for liquid crystal molecules on the ultrasonic absorption and velocity dispersion has been investigated. The binary mixture of Shiff base liquid crystals MBBA/EBBA (55:45 mole %) showed anomalous ultrasonic absorption and velocity dispersion at eutectic (Tsub(m) = -20 0 C) and clearing point (Tsub(c) = 50 0 C) at the frequency range of 5 MHz, 10MHz, 15MHz and 30 MHz. The experimental data were analyzed in terms of relaxation time and Fixman theory. The anisotropy of the propagation velocity due to the magnetic alignment was about 0.9% (the deviation between velocities propagating parallel and perpendicular to the applied field). (author)

Electrochemical behaviour of ThF4 in LiCl-KCl eutectic

International Nuclear Information System (INIS)

Agarwal, Renu; Mukerjee, S.K.; Ramakumar, K.L.

2016-01-01

Pyrochemical processing of nuclear fuels is an integral part of molten salt reactor technology. Thorium containing molten salt reactors are relevant for transmutation of minor actinides and utilizations of vast thorium resources. Understanding chemical and electrochemical behavior of actinide and lanthanide ions in chloride melts is an important task in this process. A eutectic of lithium and potassium chloride is found to be the most suitable salt for this study due to its low melting, high reduction potential and significant solubility of most of the actinide and lanthanide salts. However, electrochemistry of thorium in chloride melt is inconsistent due to dispute over the presence of Th(II) cation along with Th(IV). In the present experiments, cyclic-voltammograms of ThF 4 in LiCl-KCl eutectic salt were measured using three electrodes cell, where all the electrodes were 1 mm molybdenum wires and counter electrode wire was twisted into a spiral shape to increase surface area and was used for mixing the salts in molten state. Cyclic-voltammograms of pure eutectic melt and with ThF 4 were measured at scanning rates 50-300 mV/s, at 648 K and 723 K. Diffusion coefficient of Th 4+ was calculated using Delahay equation

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

Energy Technology Data Exchange (ETDEWEB)

Ralfs, Julie D

2002-07-01

Tissue porosity and fluid flow have been shown to be important parameters affecting the mechanical and sensorial behaviour of edible plant tissues. The quantity of fluid and the manner with which it was released on compression of the plant tissue were also important regarding the sensory perception and a good indication of any structural damage resulting from freezing, for example. Potato, carrot and Chinese water chestnut were used to study the effects freezing has on model plant tissues. Mechanical and structural measurements of the plant tissue were correlated with sensory analysis. Conventional freezing was shown to cause severe structural damage predominantly in the form of cavities between or through cells, resulting in decreases in mechanical strength and stiffness, and samples that were perceived in the mouth as 'soft' and 'wet'. The location and size of the cavities formed from ice crystals, depended on the particular plant tissue being frozen, the processing it was subjected to prior to freezing, the size of the sample and the cooling regime employed to freeze the tissue. Cavitation in the tissue resulted in an increase in tissue porosity, which enabled fluid to flow more easily from the tissue on compression, thus affecting the mechanical properties and sensory perception. Freezing damage to plant tissues was shown to be reduced, and sometimes prevented, when active antifreeze proteins (AFPs) were introduced into the tissues by vacuum infiltration or transformation and the tissue was frozen at a suitable cooling rate. Theoretical modelling was applied to the fluid flow and porosity data to test the validity of the models and to subsequently predict the mechanical behaviour of potato from the structural properties of the tissue. (author)

Micro-fractures produced in the Cadalso de los Vidrios granite (Madrid) subjected to Freeze-Thaw Durability Testing

Science.gov (United States)

Freire-Lista, D. M.; Varas-Muriel, M. J.; Fort, R.

2012-04-01

A specific leucogranite (fine to medium grain sized) from Cadalso de los Vidrios, Madrid, Spain, from where it takes the name of the stone variety, which is a traditional heritage building material used in Central Spain, was subjected to freezing-thaw durability tests or accelerated artificial ageing tests (according to Spanish standard EN 12371:2001) to assess its durability by means of ultrasonic velocity measurements (a non-destructive technique), and optical and fluorescence petrography using a polarized optical microscope (destructive technique), both techniques used before, during and after laboratory ageing tests, or in other words, what is determined is the improvement or deterioration in some properties. The measurement of the ultrasonic velocity in the leucogranite cubic test specimens along the freezing-thaw cycles shown that the velocity diminishes with the number of cycles, in relation to the decay that the stones were experiencing. This deterioration can be observed by the loss of crystalline minerals in the surface of the analyzed samples and by the micro-fractures appearance up to one centimeter deep, which have been detected by the petrographic techniques previously mentioned. The images taken by means of the fluorescence microscope clearly show the micro-fractures generated during the durability test. These images have been processed and analyzed by the UTHSCSA Image Tool program with the purpose of being able to quantify the degree of decay that this type of crystalline materials undergone, when subjected to a number of freezing-thaw test cycles. It is therefore an effective, reliable and complementary technique to that of the petrography analysis, both optical and fluorescence ones. In the first cycles of the ageing test, the micro-fractures propagate along crystals edges and during the last cycles of the test, intracrystalline micro-fractures are generated, which are developed in different ways depending on the mineralogy of the crystals. Thus

Freeze out in heavy ion reactions

International Nuclear Information System (INIS)

Csernai, Laszlo P.; Lazar, Zs.I.; Grassi, F.; Hama, Y.

1998-01-01

In fluid dynamical models the freeze out of particles across a three dimensional space-time hypersurface is discussed. The calculation of final momentum distribution of emitted particles is described for freeze out surfaces, with both space-like and time-like normals, taking into account conservation laws across the freeze out discontinuity. Generally the conservation laws lead to a change of temperature, baryon density and flow velocity at freeze out. (author)

Gypsum crystals observed in experimental and natural sea ice

DEFF Research Database (Denmark)

Geilfus, Nicolas-Xavier; Galley, Ryan; Cooper, Marc

2013-01-01

, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the “Gitterman pathway” where gypsum is predicted to precipitate. The occurrence...

Thermal properties and stabilities of the eutectic mixture: 1,6-hexanediol/lauric acid as a phase change material for thermal energy storage

International Nuclear Information System (INIS)

Han, Lipeng; Ma, Guixiang; Xie, Shaolei; Sun, Jinhe; Jia, Yongzhong; Jing, Yan

2017-01-01

Highlights: • The eutectic mixture of 1,6-hexanediol/lauric acid was studied as a phase change material. • The mass fraction of 1,6-hexanediol in eutectic point is 70%. • The melting point and latent heat are measured to be 36.92 °C and 177.11 J g −1 . • The eutectic mixture showed good thermal and cyclic stabilities. - Abstract: Thermal properties and stabilities of the eutectic mixture: 1,6-hexanediol (HE) and lauric acid (LA) as a new phase change material (PCM) for latent heat thermal energy storage (TES) were investigated. Differential scanning calorimetry (DSC) results indicated that the aforementioned HE/LA mixture with eutectic composition (70/30 wt.%) was a suitable PCM in terms of melting point (T peak = 36.92 ± 0.71 °C) and latent heat of fusion (ΔH m = 177.11 ± 7.93 J g −1 ). After 1000 thermal cycles, the change in melting point for the eutectic mixture was in the range of −0.49% to −1.19%, and the change in latent heat of fusion was in the range of −0.22% to −3.24%. The eutectic mixture was thermally and chemically stable according to results of thermogravimetric analysis (TGA), volatile test and Fourier Transform Infrared (FT-IR) spectroscopic analysis. Therefore, the HE/LA eutectic mixture is an effective TES material to reduce energy consumption.

Does deposition freezing really exist? At least different as we thought

Science.gov (United States)

Abdelmonem, Ahmed

2017-04-01

The structural and chemical properties of the surface of an IN-particle (INP) play a major role in its IN ability. This role is not well explored in terms of water/INP-surface molecular-level interactions. Recent MD simulations on deposition freezing showed that water first deposits as liquid clusters and then crystallize isothermally from there [1]. We probe freezing of water on INPs of different structural and chemical properties under varying supersaturation conditions using non-linear optical spectroscopy, mainly second harmonic generation (SHG) and sum frequency generation (SFG) [2, 3]. This presentation will show very recent preliminary experimental results comparing deposition, condensation and immersion freezing (DF, CF and IF respectively) on an atmospheric relevant metal oxide surface (mica) using supercooled SHG measurements. It is found that the signal drops upon the formation of a thin film regardless of 1) the freezing path (DF or CF), 2) the formed phase (ice or liquid), indicating a similar molecular structuring. The observed structuring similarity between DF, CF and LC films is a kick-off experimental confirmation of those computational results. References 1. Lupi, L., N. Kastelowitz, and V. Molinero, Vapor deposition of water on graphitic surfaces: Formation of amorphous ice, bilayer ice, ice I, and liquid water. The Journal of Chemical Physics, 2014. 141(18): p. 18C508. 2. Abdelmonem, A., J. Lützenkirchen, and T. Leisner, Probing ice-nucleation processes on the molecular level using second harmonic generation spectroscopy. Atmospheric Measurement Techniques, 2015. 8(8): p. 3519-3526. 3. Abdelmonem, A., et al., Surface charge-induced orientation of interfacial water suppresses heterogeneous ice nucleation on α-alumina (0001). Angewandte Chemie (Submitted), 2017.

On the performance of a novel grain refiner in hyper-eutectic Al-Si cast alloys

OpenAIRE

Bolzoni, L; Nowak, M; Hari Babu, N

2014-01-01

The stringent requirements for pollution reduction are pushing the automotive industry towards the employment of lightweight structures and, therefore, aluminium and its alloys play a remarkable role. Al-Si casting alloy with eutectic or hyper- eutectic compositions are, normally, employed for the production of high performance automotive products such as pistons and engine blocks which have to withstand critical loading conditions (i.e. high temperature, high pressure and corrosive exhaust g...

Micro/nano encapsulation of some paraffin eutectic mixtures with poly(methyl methacrylate) shell: Preparation, characterization and latent heat thermal energy storage properties

International Nuclear Information System (INIS)

Sarı, Ahmet; Alkan, Cemil; Bilgin, Cahit

2014-01-01

Graphical abstract: Four kinds of micro/nano capsules, PMMA/(C17-C24), PMMA/(C19-C18), PMMA/(C19-C24) and PMMA/(C20-C24), were synthesized successfully as novel encapsulated phase change materials (PCMs) for the different monomer/PEM ratios via emulsion polymerization. The FTIR spectroscopy analysis confirmed the polymerization reaction occurred around the PEMs to be used as core materials. The POM, SEM and PSD analysis results showed that the synthesized PMMA/PEM micro/nano capsules had spherical shape appearance and micro/nano sizes. DSC analysis measurements revealed that the prepared micro/nano capsules containing the highest PEM content had a melting temperature range of about 20–36 °C and latent heat capacities in the range of about 86–169 J/g. TGA findings demonstrated that the encapsulated PEMs had good thermal reliability and chemical stability even after subjecting them to 5000 melting/freezing cycles. Furthermore, the prepared micro/nano capsules had reasonable thermal conductivity values and fine melting–freezing reversibility. - Highlights: • PSD analysis results showed that the encapsulated PEMs had micro/nano sized-spheres. • The encapsulated PEMs melt in the temperature range of about 20–36 °C. • The encapsulated PEMs had latent heat capacities of in the range of about 86–169 J/g. • TGA results demonstrated that they had good thermal stability. • The encapsulated PEMs had good thermal conductivity and phase change reversibility. - Abstract: This work is aimed to prepare, characterize and determine the latent heat thermal energy storage properties of micro/nano encapsulated paraffin eutectic mixtures (PEMs) with polymethylmethacrylate (PMMA) shell. The eutectic combination ratios and optimum melting temperatures of C17-C24, C19-C18, C19-C24 and C20-C24 mixtures were find out prior to the encapsulation processes. Four kinds of micro/nano capsules, PMMA/(C17-C24), PMMA/(C19-C18), PMMA/(C19-C24) and PMMA/(C20-C24), were synthesized

Freeze-dried microarterial allografts

International Nuclear Information System (INIS)

Raman, J.; Hargrave, J.C.

1990-01-01

Rehydrated freeze-dried microarterial allografts were implanted to bridge arterial defects using New Zealand White rabbits as the experimental model. Segments of artery from the rabbit ear and thigh were harvested and preserved for a minimum of 2 weeks after freeze-drying. These allografts, approximately 1 mm in diameter and ranging from 1.5 to 2.5 cm in length, were rehydrated and then implanted in low-pressure and high-pressure arterial systems. Poor patency was noted in low-pressure systems in both allografts and autografts, tested in 12 rabbits. In the high-pressure arterial systems, allografts that were freeze-dried and reconstituted failed in a group of 10 rabbits with an 8-week patency rate of 30 percent. Gamma irradiation in an effort to reduce infection and antigenicity of grafts after freeze-drying was associated with a patency rate of 10 percent at 8 weeks in this system in another group of 10 rabbits. Postoperative cyclosporin A therapy was associated with a patency rate of 22.2 percent in the high-pressure arterial system in a 9-rabbit group. Control autografts in this system in a group of 10 rabbits showed a 100 percent patency at 8 weeks. Microarterial grafts depend on perfusion pressure of the vascular bed for long-term patency. Rehydrated freeze-dried microarterial allografts do not seem to function well in lengths of 1 to 2.5 cm when implanted in a high-pressure arterial system. Freeze-dried arterial allografts are probably not antigenic

Synthesis and analysis of silicon nanowire below Si-Au eutectic temperatures using very high frequency plasma enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Hamidinezhad, Habib; Wahab, Yussof; Othaman, Zulkafli; Ismail, Abd Khamim

2011-01-01

Silicon nanowires (SiNWs) were synthesized from pure silane precursor gas and Au nanoparticles catalyst at below Au-Si eutectic temperature. The SiNWs were grown onto Si (1 1 1) substrates using very high frequency plasma enhanced chemical vapor deposition via a vapor-solid-solid mechanism at temperatures ranging from 363 to 230 deg. C. The morphology of the synthesized SiNWs was characterized by means of field emission scanning electron microscope equipped with energy dispersive X-ray, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscope. Results demonstrated that the SiNWs can be grown at the temperature as low as 250 deg. C. In addition, it was revealed that the grown wires were silicon-crystallized.

Effect of titanium on the near eutectic grey iron

DEFF Research Database (Denmark)

Moumeni, Elham; Tiedje, Niels Skat; Hattel, Jesper Henri

The effect of Titanium on the microstructure of grey iron was investigated experimentally in this work. Tensile test bars of grey cast iron of near eutectic alloys containing 0.01, 0.1, 0.26 and 0.35% Ti, respectively were made in green sand moulds. Chemical analysis, metallographic investigation...

Chip bonding of low-melting eutectic alloys by transmitted laser radiation

Science.gov (United States)

Hoff, Christian; Venkatesh, Arjun; Schneider, Friedrich; Hermsdorf, Jörg; Bengsch, Sebastian; Wurz, Marc C.; Kaierle, Stefan; Overmeyer, Ludger

2017-06-01

Present-day thermode bond systems for the assembly of radio-frequency identification (RFID) chips are mechanically inflexible, difficult to control, and will not meet future manufacturing challenges sufficiently. Chip bonding, one of the key processes in the production of integrated circuits (ICs), has a high potential for optimization with respect to process duration and process flexibility. For this purpose, the technologies used, so far, are supposed to be replaced by a transmission laser-bonding process using low-melting eutectic alloys. In this study, successful bonding investigations of mock silicon chips and of RFID chips on flexible polymer substrates are presented using the low-melting eutectic alloy, 52In48Sn, and a laser with a wavelength of 2 μm.

Modelling of Eutectic Saturation Influence on Microstructure in Thin Wall Ductile Iron Casting Using Cellular Automata

Directory of Open Access Journals (Sweden)

Burbelko A.A.

2012-12-01

Full Text Available The mathematical model of the globular eutectic solidification in 2D was designed. Proposed model is based on the Cellular Automaton Finite Differences (CA-FD calculation method. Model has been used for studies of the primary austenite and of globular eutectic grains growth during the ductile iron solidification in the thin wall casting. Model takes into account, among other things, non-uniform temperature distribution in the casting wall cross-section, kinetics of the austenite and graphite grains nucleation, and non-equilibrium nature of the interphase boundary migration. Calculation of eutectic saturation influence (Sc = 0.9 - 1.1 on microstructure (austenite and graphite fraction, density of austenite and graphite grains and temperature curves in 2 mm wall ductile iron casting has been done.

Transient and steady state creep response of ice I and magnesium sulfate hydrate eutectic aggregates

Science.gov (United States)

McCarthy, C.; Cooper, R.F.; Goldsby, D.L.; Durham, W.B.; Kirby, S.H.

2011-01-01

Using uniaxial compression creep experiments, we characterized the transient and steady state deformation behaviors of eutectic aggregates of system ice I and MgSO4 11H2O (MS11; meridianiite), which has significance because of its likely presence on moons of the outer solar system. Synthetic samples of eutectic liquid bulk composition, which produce eutectic colonies containing 0.35-0.50 volume fraction MS11, were tested as functions of colony size and lamellar spacing, temperature (230-250 K), and confining pressure (0.1 and 50 MPa) to strains ???0.2. Up to a differential stress of 6 MPa, the ice I-MS11 aggregates display an order of magnitude higher effective viscosity and higher stress sensitivity than do aggregates of pure polycrystalline ice at the same conditions. The creep data and associated microstructural observations demonstrate, however, that the aggregates are additionally more brittle than pure ice, approaching rate-independent plasticity that includes rupture of the hydrate phase at 6-8 MPa, depending on the scale of the microstructure. Microstructures of deformed samples reveal forms of semibrittle flow in which the hydrate phase fractures while the ice phase deforms plastically. Semibrittle flow in the icy shell of a planetary body would truncate the lithospheric strength envelope and thereby decrease the depth to the brittle-ductile transition by 55% and reduce the failure limit for compressional surface features from 10 to ???6 MPa. A constitutive equation that includes eutectic colony boundary sliding and intracolony flow is used to describe the steady state rheology of the eutectic aggregates. Copyright ?? 2011 by the American Geophysical Union.

The Influence of Cr on the Solidification Behavior of Polycrystalline γ(Ni)/ γ'(Ni3Al)- δ(Ni3Nb) Eutectic Ni-Base Superalloys

Science.gov (United States)

Xie, Mengtao; Helmink, Randolph; Tin, Sammy

2012-04-01

In the current investigation, the effect of Cr on the solidification characteristics and as-cast microstructure of pseudobinary γ- δ eutectic alloys based on a near-eutectic composition (Ni-5.5Al-13.5Nb at. pct) was investigated. It was found that Cr additions promote the formation of a higher volume fraction of γ- δ eutectic microstructure in the interdendritic region. Increasing levels of Cr also triggered morphological changes in the γ- δ eutectic and the formation of γ- γ'- δ ternary eutectic during the last stage of solidification. A detailed characterization of the as-cast alloys also revealed that Cr additions suppressed the liquidus, solidus, and γ' precipitation temperature of these γ/ γ'- δ eutectic alloys. A comparison of the experimental results with thermodynamic calculations using the CompuTherm Pandat database (CompuTherm LLC, Madison, WI) showed qualitative agreement.

Cognitive Factors Affecting Freeze-like Behavior in Humans.

Science.gov (United States)

Alban, Michael W; Pocknell, Victoria

2017-01-01

Contemporary research on survival-related defensive behaviors has identified physiological markers of freeze/flight/fight. Our research focused on cognitive factors associated with freeze-like behavior in humans. Study 1 tested if an explicit decision to freeze is associated with the psychophysiological state of freezing. Heart rate deceleration occurred when participants chose to freeze. Study 2 varied the efficacy of freezing relative to other defense options and found "freeze" was responsive to variations in the perceived effectiveness of alternative actions. Study 3 tested if individual differences in motivational orientation affect preference for a "freeze" option when the efficacy of options is held constant. A trend in the predicted direction suggested that naturally occurring cognitions led loss-avoiders to select "freeze" more often than reward-seekers. In combination, our attention to the cognitive factors affecting freeze-like behavior in humans represents a preliminary step in addressing an important but neglected research area.

Parameterizing the competition between homogeneous and heterogeneous freezing in cirrus cloud formation – monodisperse ice nuclei

Directory of Open Access Journals (Sweden)

D. Barahona

2009-01-01

Full Text Available We present a parameterization of cirrus cloud formation that computes the ice crystal number and size distribution under the presence of homogeneous and heterogeneous freezing. The parameterization is very simple to apply and is derived from the analytical solution of the cloud parcel equations, assuming that the ice nuclei population is monodisperse and chemically homogeneous. In addition to the ice distribution, an analytical expression is provided for the limiting ice nuclei number concentration that suppresses ice formation from homogeneous freezing. The parameterization is evaluated against a detailed numerical parcel model, and reproduces numerical simulations over a wide range of conditions with an average error of 6±33%. The parameterization also compares favorably against other formulations that require some form of numerical integration.

Possible Mechanisms for Turbofan Engine Ice Crystal Icing at High Altitude

Science.gov (United States)

Tsao, Jen-Ching; Struk, Peter M.; Oliver, Michael J.

2016-01-01

A thermodynamic model is presented to describe possible mechanisms of ice formation on unheated surfaces inside a turbofan engine compression system from fully glaciated ice crystal clouds often formed at high altitude near deep convective weather systems. It is shown from the analysis that generally there could be two distinct types of ice formation: (1) when the "surface freezing fraction" is in the range of 0 to 1, dominated by the freezing of water melt from fully or partially melted ice crystals, the ice structure is formed from accretion with strong adhesion to the surface, and (2) when the "surface melting fraction" is the range of 0 to 1, dominated by the further melting of ice crystals, the ice structure is formed from accumulation of un-melted ice crystals with relatively weak bonding to the surface. The model captures important qualitative trends of the fundamental ice-crystal icing phenomenon reported earlier (Refs. 1 and 2) from the research collaboration work by NASA and the National Research Council (NRC) of Canada. Further, preliminary analysis of test data from the 2013 full scale turbofan engine ice crystal icing test (Ref. 3) conducted in the NASA Glenn Propulsion Systems Laboratory (PSL) has also suggested that (1) both types of ice formation occurred during the test, and (2) the model has captured some important qualitative trend of turning on (or off) the ice crystal ice formation process in the tested engine low pressure compressor (LPC) targeted area under different icing conditions that ultimately would lead to (or suppress) an engine core roll back (RB) event.

Eutectic fusion used for the survey of transport of mass in metallic solutions

International Nuclear Information System (INIS)

Savane, Y.S.; Katty, S.; Balde, M.L.; Cisse, S.; Rogov, V.I.

1997-09-01

The phenomenon of eutectic fusion could be used for the survey of transport of mass in metallic solutions, which allows to determine the part of the ionic conductibility in the solutions. The survey done in the system In 2 Bi Bi-In at a temperature of 72 deg. C with a current of 4A allowed to find a ionic current of 2,6.10 -3 which constitutes about 0,07% of the total current. So the part of ionic conductibility in the eutectic fusion of the system In 2 Bi Bi-In is of 0,07%. (author)

A potentiostatic and galvanostatic study of the selective dissolution of Cd/Pb eutectic alloy

International Nuclear Information System (INIS)

Sokharev, N.P.; Rabdel, A.A.; Zhadanov, V.V.

1986-01-01

The authors consider the selective dissolution (SD) of the electronegative component of a two-phase, eutectic alloy (Cd/Pb) under galvanostatic conditions. Treating this process as the extraction of a solid substance from a porous matrix, the distribution of the concentration of EC ions, c(x, t), can be described by a differential equation (presented). Experimental data are presented in two equations which are applicable for the description of the selective dissolution process of the electronegative component of a eutectic alloy under conditions of concentration polarization

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 and...

9 CFR 590.534 - Freezing facilities.

Science.gov (United States)

2010-01-01

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

3 CFR - Pay Freeze

Science.gov (United States)

2010-01-01

... 3 The President 1 2010-01-01 2010-01-01 false Pay Freeze Presidential Documents Other Presidential Documents Memorandum of January 21, 2009 Pay Freeze Memorandum for the Assistant to the President and Chief... the White House staff forgo pay increases until further notice. Accordingly, as a signal of our shared...

Large-scale membrane transfer process: its application to single-crystal-silicon continuous membrane deformable mirror

International Nuclear Information System (INIS)

Wu, Tong; Sasaki, Takashi; Hane, Kazuhiro; Akiyama, Masayuki

2013-01-01

This paper describes a large-scale membrane transfer process developed for the construction of large-scale membrane devices via the transfer of continuous single-crystal-silicon membranes from one substrate to another. This technique is applied for fabricating a large stroke deformable mirror. A bimorph spring array is used to generate a large air gap between the mirror membrane and the electrode. A 1.9 mm × 1.9 mm × 2 µm single-crystal-silicon membrane is successfully transferred to the electrode substrate by Au–Si eutectic bonding and the subsequent all-dry release process. This process provides an effective approach for transferring a free-standing large continuous single-crystal-silicon to a flexible suspension spring array with a large air gap. (paper)

Comment on the consistency of truncated nonlinear integral equation based theories of freezing

International Nuclear Information System (INIS)

Cerjan, C.; Bagchi, B.; Rice, S.A.

1985-01-01

We report the results of two studies of aspects of the consistency of truncated nonlinear integral equation based theories of freezing: (i) We show that the self-consistent solutions to these nonlinear equations are unfortunately sensitive to the level of truncation. For the hard sphere system, if the Wertheim--Thiele representation of the pair direct correlation function is used, the inclusion of part but not all of the triplet direct correlation function contribution, as has been common, worsens the predictions considerably. We also show that the convergence of the solutions found, with respect to number of reciprocal lattice vectors kept in the Fourier expansion of the crystal singlet density, is slow. These conclusions imply great sensitivity to the quality of the pair direct correlation function employed in the theory. (ii) We show the direct correlation function based and the pair correlation function based theories of freezing can be cast into a form which requires solution of isomorphous nonlinear integral equations. However, in the pair correlation function theory the usual neglect of the influence of inhomogeneity of the density distribution on the pair correlation function is shown to be inconsistent to the lowest order in the change of density on freezing, and to lead to erroneous predictions

Al based ultra-fine eutectic with high room temperature plasticity and elevated temperature strength

Energy Technology Data Exchange (ETDEWEB)

Tiwary, C.S., E-mail: cst311@gmail.com [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India); Kashyap, S. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India); Kim, D.H. [Center for Non-Crystalline Materials, Department of Metallurgical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Chattopadhyay, K. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012, Karnataka (India)

2015-07-15

Developments of aluminum alloys that can retain strength at and above 250 °C present a significant challenge. In this paper we report an ultrafine scale Al–Fe–Ni eutectic alloy with less than 3.5 at% transition metals that exhibits room temperature ultimate tensile strength of ~400 MPa with a tensile ductility of 6–8%. The yield stress under compression at 300 °C was found to be 150 MPa. We attribute it to the refinement of the microstructure that is achieved by suction casting in copper mold. The characterization using scanning and transmission electron microscopy (SEM and TEM) reveals an unique composite structure that contains the Al–Al{sub 3}Ni rod eutectic with spacing of ~90 nm enveloped by a lamellar eutectic of Al–Al{sub 9}FeNi (~140 nm). Observation of subsurface deformation under Vickers indentation using bonded interface technique reveals the presence of extensive shear banding during deformation that is responsible for the origin of ductility. The dislocation configuration in Al–Al{sub 3}Ni eutectic colony indicates accommodation of plasticity in α-Al with dislocation accumulation at the α-Al/Al{sub 3}Ni interface boundaries. In contrast the dislocation activities in the intermetallic lamellae are limited and contain set of planner dislocations across the plates. We present a detailed analysis of the fracture surface to rationalize the origin of the high strength and ductility in this class of potentially promising cast alloy.

Measurement of solid-liquid interfacial energy in the In-Bi eutectic alloy at low melting temperature

International Nuclear Information System (INIS)

Marasli, N; Akbulut, S; Ocak, Y; Keslioglu, K; Boeyuek, U; Kaya, H; Cadirli, E

2007-01-01

The Gibbs-Thomson coefficient and solid-liquid interfacial energy of the solid In solution in equilibrium with In Bi eutectic liquid have been determined to be (1.46 ± 0.07) x 10 -7 K m and (40.4 ± 4.0) x 10 -3 J m -2 by observing the equilibrated grain boundary groove shapes. The grain boundary energy of the solid In solution phase has been calculated to be (79.0 ± 8.7) x 10 -3 J m -2 by considering force balance at the grain boundary grooves. The thermal conductivities of the In-12.4 at.% Bi eutectic liquid phase and the solid In solution phase and their ratio at the eutectic melting temperature (72 deg. C) have also been measured with radial heat flow apparatus and Bridgman-type growth apparatus

Experimental investigation of thermophysical properties of eutectic Mo–C, graphite and tantalum at high temperatures

International Nuclear Information System (INIS)

Senchenko, V N; Belikov, R S; Popov, V S

2016-01-01

An experimental technique based on fast electrical heating for investigation of thermophysical properties of refractory materials under high pressures and at high temperatures is considered. A set of thermophysical properties of refractory materials such as specific enthalpy, specific heat capacity, specific resistivity, melting heat of eutectic Mo-C and thermal expansion of graphite and tantalum were determined. The obtained temperature of eutectic melting of MoC 0.82 shows close agreement with equilibrium Mo-C phase diagram. (paper)

New eutectic ionic liquids for lipase activation and enzymatic preparation of biodiesel†

Science.gov (United States)

Zhao, Hua; Baker, Gary A.; Holmes, Shaletha

2012-01-01

The enzymatic preparation of biodiesel has been hampered by the lack of suitable solvents with desirable properties such as high lipase compatibility, low cost, low viscosity, high biodegradability, and ease of product separation. Recent interest in using ionic liquids (ILs) as advanced reaction media has led to fast reaction rates and high yields in the enzymatic synthesis of biodiesel. However, conventional (i.e., cation–anion paired) ILs based on imidazolium and other quaternary ammonium salts remain too expensive for wide application at industrial scales. In this study, we report on newly-synthesized eutectic ILs derived from choline acetate or choline chloride coupled with biocompatible hydrogen-bond donors, such as glycerol. These eutectic solvents have favorable properties including low viscosity, high biodegradability, and excellent compatibility with Novozym® 435, a commercial immobilized Candida antarctica lipase B. Furthermore, in a model biodiesel synthesis system, we demonstrate high reaction rates for the enzymatic transesterification of Miglyol® oil 812 with methanol, catalyzed by Novozym® 435 in choline acetate/glycerol (1 : 1.5 molar ratio). The high conversion (97%) of the triglyceride obtained within 3 h, under optimal conditions, suggests that these novel eutectic solvents warrant further exploration as potential media in the enzymatic production of biodiesel. PMID:21283901

Freezing nucleation apparatus puts new slant on study of biological ice nucleators in precipitation

Science.gov (United States)

Stopelli, E.; Conen, F.; Zimmermann, L.; Alewell, C.; Morris, C. E.

2014-01-01

For decades, drop-freezing instruments have contributed to a better understanding of biological ice nucleation and its likely implications for cloud and precipitation development. Yet, current instruments have limitations. Drops analysed on a cold stage are subject to evaporation and potential contamination. The use of closed tubes provides a partial solution to these problems, but freezing events are still difficult to be clearly detected. Here, we present a new apparatus where freezing in closed tubes is detected automatically by a change in light transmission upon ice development, caused by the formation of air bubbles and crystal facets that scatter light. Risks of contamination and introduction of biases linked to detecting the freezing temperature of a sample are then minimized. To illustrate the performance of the new apparatus we show initial results of two assays with snow samples. In one, we repeatedly analysed the sample (208 tubes) over the course of a month with storage at +4 °C, during which evidence for biological ice nucleation activity emerged through an increase in the number of ice nucleators active around -4 °C. In the second assay, we indicate the possibility of increasingly isolating a single ice nucleator from a precipitation sample, potentially determining the nature of a particle responsible for a nucleation activity measured directly in the sample. These two seminal approaches highlight the relevance of this handy apparatus for providing new points of view in biological ice nucleation research.

Reversed phase HPLC analysis of stability and microstructural effects on degradation kinetics of β-carotene encapsulated in freeze-dried maltodextrin-emulsion systems.

Science.gov (United States)

Harnkarnsujarit, Nathdanai; Charoenrein, Sanguansri; Roos, Yrjö H

2012-09-26

Degradation of dispersed lipophilic compounds in hydrophilic solids depends upon matrix stability and lipid physicochemical properties. This study investigated effects of solid microstructure and size of lipid droplets on the stability of dispersed β-carotene in freeze-dried systems. Emulsions of β-carotene in sunflower oil were dispersed in maltodextrin systems (M040/DE6, M100/DE11, and M250/DE25.5) (8% w/w oil) and prefrozen at various freezing conditions prior to freeze-drying to control nucleation and subsequent pore size and structural collapse of freeze-dried solids. The particle size, physical state, and β-carotene contents of freeze-dried emulsions were measured during storage at various water activity (a(w)) using a laser particle size analyzer, differential scanning calorimeter, and high performance liquid chromatography (HPLC), respectively. The results showed that M040 stabilized emulsions in low temperature freezing exhibited lipid crystallization. Collapse of solids in storage at a(w) which plasticized systems to the rubbery state led to flow and increased the size of oil droplets. Degradation of β-carotene analyzed using a reversed-phase C(30) column followed first-order kinetics. Porosity of solids had a major effect on β-carotene stability; however, the highest stability was found in fully plasticized and collapsed solids.

Aliphatic-aromatic separation using deep eutectic solvents as extracting agents

NARCIS (Netherlands)

Rodriguez Rodriguez, Nerea; Fernandez Requejo, Patricia; Kroon, Maaike

2015-01-01

The separation of aliphatic and aromatic compounds is a great challenge for chemical engineers. There is no efficient separation process for mixtures with compositions lower than 20 wt % in aromatics. In this work, the feasibility of two different deep eutectic solvents (DESs) as novel extracting

Quantitative Comparison of Ternary Eutectic Phase-Field Simulations with Analytical 3D Jackson-Hunt Approaches

Science.gov (United States)

Steinmetz, Philipp; Kellner, Michael; Hötzer, Johannes; Nestler, Britta

2018-02-01

For the analytical description of the relationship between undercoolings, lamellar spacings and growth velocities during the directional solidification of ternary eutectics in 2D and 3D, different extensions based on the theory of Jackson and Hunt are reported in the literature. Besides analytical approaches, the phase-field method has been established to study the spatially complex microstructure evolution during the solidification of eutectic alloys. The understanding of the fundamental mechanisms controlling the morphology development in multiphase, multicomponent systems is of high interest. For this purpose, a comparison is made between the analytical extensions and three-dimensional phase-field simulations of directional solidification in an ideal ternary eutectic system. Based on the observed accordance in two-dimensional validation cases, the experimentally reported, inherently three-dimensional chain-like pattern is investigated in extensive simulation studies. The results are quantitatively compared with the analytical results reported in the literature, and with a newly derived approach which uses equal undercoolings. A good accordance of the undercooling-spacing characteristics between simulations and the analytical Jackson-Hunt apporaches are found. The results show that the applied phase-field model, which is based on the Grand potential approach, is able to describe the analytically predicted relationship between the undercooling and the lamellar arrangements during the directional solidification of a ternary eutectic system in 3D.

Formation and microstructure of Al{sub 2}O{sub 3}-YAG eutectic ceramics by phase transformation from metastable system to equilibrium system

Energy Technology Data Exchange (ETDEWEB)

Nagira, Tomoya; Yasuda, Hideyuki; Yoshiya, Masato [Department of Adaptive Machine Systems, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)], E-mail: nagira@ams.eng.osaka-u.ac.jp

2009-05-01

Unidirectionally solidified Al{sub 2}O{sub 3}-YAG(Y{sub 3}Al{sub 5}O{sub 12}: yttrium-aluminum-garnet) eutectic ceramic composites have been recognized as encouraging heat-resistance materials because of the superior mechanical properties at high temperatures. In addition to the excellent mechanical properties at high temperatures, some interesting solidification phenomena have been reported in the Al{sub 2}O{sub 3}-Y{sub 2}O{sub 3} system. The Al{sub 2}O{sub 3}-YAG equilibrium eutectic at 2099 K and the Al{sub 2}O{sub 3}-YAP metastable eutectic at 1975 K exist in the Al{sub 2}O{sub 3}-Y{sub 2}O{sub 3} system. The heating the metastable eutectic up to temperatures above the metastable eutectic temperature produced the undercooled melt. Solidification in the equilibrium path accompanied the melting of the metastable eutectic. The solidification process using undercooled melt resulted in the fine and uniform eutectic structure. In this study, the effect of the initial Al{sub 2}O{sub 3}-YAP particles size on the undercooled melt formation was examined. The Al{sub 2}O{sub 3}-YAP particles with diameters more than several {mu}m resulted in the transformation through the undercooled melt. EBSD analysis showed that the domains of Al{sub 2}O{sub 3} grains with same crystallographic orientation were observed and that their domain size depended on the Al{sub 2}O{sub 3}-YAP particles size. On the other hand, for the Al{sub 2}O{sub 3}-YAP particles with a diameter of 500 nm, the each Al{sub 2}O{sub 3} grain with diameter of about 1 {mu}m had the different crystallographic orientations, which suggested that the transformation from metastable eutectic to equilibrium eutectic occurred in the solid state. The increase in the Al{sub 2}O{sub 3}-YAP free surface area suppressed the undercooled melt formation.

Comparative study of ice nucleating efficiency of K-feldspar in immersion and deposition freezing modes

Science.gov (United States)

Hiron, T.; Hoffmann, N.; Peckhaus, A.; Kiselev, A. A.; Leisner, T.; Flossmann, A. I.

2016-12-01

One of the main challenges in understanding the evolution of Earth's climate resides in the understanding the role of ice nucleation on the development of tropospheric clouds as well as its initiation. K-feldspar is known to be a very active ice nucleating particle and this study focuses on the characterization of its activity in two heterogeneous nucleation modes, immersion and deposition freezing.We use a newly built humidity-controlled cold stage allowing the simultaneous observation of up to 2000 identical 0.6-nanoliter droplets containing suspension of mineral dust particles. The droplets are first cooled down to observe immersion freezing, the obtained ice crystals are then evaporated and finally, the residual particles are exposed to the water vapor supersaturated with respect to ice.The ice nucleation abilities for the individual residual particles are then compared for the different freezing modes and correlation between immersion ice nuclei and deposition ice nuclei is investigated.Based on the electron microscopy analysis of the residual particles, we discuss the possible relationship between the ice nucleation properties of feldspar and its microstructure. Finally, we discuss the atmospheric implications of our experimental results, using DESCAM, a 1.5D bin-resolved microphysics model.

Potential Process for the Decontamination of Pyro-electrometallurgical LiCl-KCl Eutectic Salt Electrolyte

International Nuclear Information System (INIS)

Griffith, Christopher S.; Sizgek, Erden; Sizgek, Devlet; Luca, Vittorio

2008-01-01

Presented here is a potential option with experimental validation for the decontamination of LiCl-KCl eutectic salt electrolyte from a pyro-electrometallurgical process by employing already developed inorganic ion exchange materials. Adsorbent materials considered include titano-silicates and molybdo- and tungstophosphates for Cs extraction, Si-doped antimony pyrochlore for Sr extraction and hexagonal tungsten bronzes for lanthanide (LN) and minor actinide (MA) polishing. Encouraging results from recent investigations on the removal of target elements (Cs, Sr and LN) from aqueous solutions containing varying concentrations of alkali and alkali metal contaminants which would be akin to a solution formed from the dissolution of spent LiCl-KCl eutectic salt electrolyte are presented. Further investigations have also shown that the saturated adsorbents can be treated at relatively low temperatures to afford potential waste forms for the adsorbed elements. Efficient evaporation and drying of a solution of dissolved LiCl-KCl eutectic salt electrolyte (50 L, 5 L.h -1 ) has been demonstrated using a Microwave-Heated Mechanical Fluidized Bed (MWMFB) apparatus. (authors)

Potential Process for the Decontamination of Pyro-electrometallurgical LiCl-KCl Eutectic Salt Electrolyte

Energy Technology Data Exchange (ETDEWEB)

Griffith, Christopher S.; Sizgek, Erden; Sizgek, Devlet; Luca, Vittorio [Australian Nuclear Science and Technology Organisation (ANSTO), Institute of Materials Engineering, New Illawarra Road, Lucas Heights, New South Wales, 2234 (Australia)

2008-07-01

Presented here is a potential option with experimental validation for the decontamination of LiCl-KCl eutectic salt electrolyte from a pyro-electrometallurgical process by employing already developed inorganic ion exchange materials. Adsorbent materials considered include titano-silicates and molybdo- and tungstophosphates for Cs extraction, Si-doped antimony pyrochlore for Sr extraction and hexagonal tungsten bronzes for lanthanide (LN) and minor actinide (MA) polishing. Encouraging results from recent investigations on the removal of target elements (Cs, Sr and LN) from aqueous solutions containing varying concentrations of alkali and alkali metal contaminants which would be akin to a solution formed from the dissolution of spent LiCl-KCl eutectic salt electrolyte are presented. Further investigations have also shown that the saturated adsorbents can be treated at relatively low temperatures to afford potential waste forms for the adsorbed elements. Efficient evaporation and drying of a solution of dissolved LiCl-KCl eutectic salt electrolyte (50 L, 5 L.h{sup -1}) has been demonstrated using a Microwave-Heated Mechanical Fluidized Bed (MWMFB) apparatus. (authors)

Fusion technology for the production of PbLi eutectic alloys; Obtencion de aleaciones eutecticas PbLi mediante procesos de fusion

Energy Technology Data Exchange (ETDEWEB)

Barrena, M. J.; Gomez de Salazar, J. M.; Quinones, J.; Pascual, L.; Soria, A.

2012-07-01

The development of thermonuclear experimental reactor (ITER), whose objective is to produce energy from nuclear fusion, has raised the study of Pb-Li eutectic alloys, as they have been selected for the manufacture of test blanket modules (TBM). However, during the manufacturing process of the Pb-Li alloys, thermal conditions used result in a loss of litium element, which inhibits the formation of eutectic structures. In this work we have done fusion of pure lead and lithium, evaluating different process parameters to obtain Pb-Li (17 at. %) eutectic alloys. The alloys manufactured were characterized by DSC, SEM-EDX and microhardness tests. From these studies we noted that the used of an induction reactor and the process parameters optimized to obtain Pb-Li alloy allow for completely eutectic ingots and high chemical homogeneity and microstructural. (Author) 26 refs.

Co-crystal of (R,R)-1,2-cyclohexanediol with (R,R)-tartaric acid, a key structure in resolution of the ({+-})-trans-diol by supercritical extraction, and the related ternary phase system

Energy Technology Data Exchange (ETDEWEB)

Thorey, Paul [Department of Chemical and Environmental Process Engineering, Budapest University of Technology and Economics, H-1521 Budapest (Hungary); Bombicz, Petra [Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Science, H-1525 Budapest (Hungary); Szilagyi, Imre Miklos [Material Structure and Modeling Research Group, Hungarian Academy of Sciences, H-1111 Budapest (Hungary); Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1521 Budapest (Hungary); Molnar, Peter; Bansaghi, Gyoergy; Szekely, Edit; Simandi, Bela [Department of Chemical and Environmental Process Engineering, Budapest University of Technology and Economics, H-1521 Budapest (Hungary); Parkanyi, Laszlo [Institute of Structural Chemistry, Chemical Research Center, Hungarian Academy of Science, H-1525 Budapest (Hungary); Pokol, Gyoergy [Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1521 Budapest (Hungary); Madarasz, Janos, E-mail: madarasz@mail.bme.hu [Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, H-1521 Budapest (Hungary)

2010-01-10

A novel co-crystal of trans-(R,R)-1,2-cyclohexanediol and (R,R)-tartaric acid (with 1:1 molar ratio, 1) has been found to be a key crystalline compound in the improved resolution of ({+-})-trans-1,2-cyclohexanediol by supercritical fluid extraction. The molecular and crystal structure of this co-crystal, which crystallizes in orthorhombic crystal system (space group P2{sub 1}2{sub 1}2{sub 1}, a = 6.7033(13) A, b = 7.2643(16), c = 24.863(5), Z = 4), has been solved by single crystal X-ray diffraction (R = 0.064). The packing arrangement consists of two dimensional layers of sandwich-like sheets, where the inner part is constructed by double layers of tartaric acids which hydrophilicity is 'covered' on both upper and bottom side by cyclohexanediols with the hydrophobic cyclohexane rings pointing outward. Thus, a rather complex hydrogen bonding pattern is constructed. The relatively high melting point (133 {sup o}C) observed by both simultaneous TG/DTA and DSC, and the main features of FTIR-spectrum of 1 are explained by the increased stability of this crystal structure. DSC studies on binary mixtures of co-crystal 1 with (R,R)-1,2-cyclohexanediol or (R,R)-tartaric acid, revealed eutectic temperatures of T{sub eu} = 100 or 131 {sup o}C, respectively. Between (S,S)-1,2-cyclohexanediol and (R,R)-tartaric acid a eutectic temperature of T{sub eu} = 85 {sup o}C have also been observed. The phase relations have been confirmed by powder X-ray diffraction, as well.

Analysis of isothermal and cooling rate dependent immersion freezing by a unifying stochastic ice nucleation model

Science.gov (United States)

Alpert, P. A.; Knopf, D. A.

2015-05-01

apparent cooling rate dependence ofJhet is explained by assuming identical ISA in each droplet. When accounting for ISA variability, the cooling rate dependence of ice nucleation kinetics vanishes as expected from classical nucleation theory. The model simulations allow for a quantitative experimental uncertainty analysis for parameters Ntot, T, RH, and the ISA variability. In an idealized cloud parcel model applying variability in ISAs for each droplet, the model predicts enhanced immersion freezing temperatures and greater ice crystal production compared to a case when ISAs are uniform in each droplet. The implications of our results for experimental analysis and interpretation of the immersion freezing process are discussed.

Canalization of freeze tolerance in an alpine grasshopper.

Science.gov (United States)

Hawes, Timothy C

2015-10-01

In the Rock and Pillar Range, New Zealand, the alpine grasshopper, Sigaus australis Hutton, survives equilibrium freezing (EF) all-year round. A comparison of freeze tolerance (FT) in grasshoppers over four austral seasons for a 1 year period finds that: (a) the majority (>70%) of the sample population of grasshoppers survive single freeze-stress throughout the year; (b) exposure to increased freeze stress (multiple freeze-stress events) does not lead to a loss of freeze tolerance; and (c) responses to increased freeze stress reveal seasonal tuning of the FT adaptation to environmental temperatures. The Rock and Pillar sample population provides a clear example of the canalization of the FT adaptation. Seasonal variability in the extent of tolerance of multiple freezing events indicates that physiology is modulated to environmental temperatures by phenotypic plasticity - i.e. the FT adaptation is permanent and adjustable. Copyright © 2015 Elsevier Inc. All rights reserved.

Electrodeposition of Zn and Cu–Zn alloy from ZnO/CuO precursors in deep eutectic solvent

Energy Technology Data Exchange (ETDEWEB)

Xie, Xueliang [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zou, Xingli, E-mail: xinglizou@shu.edu.cn [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Lu, Xionggang, E-mail: luxg@shu.edu.cn [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Lu, Changyuan; Cheng, Hongwei; Xu, Qian [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhou, Zhongfu [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ (United Kingdom)

2016-11-01

Graphical abstract: Micro/nanostructured Zn and Cu–Zn alloy films have been electrodeposited directly from ZnO/CuO precursors in ChCl/urea-based DES, the typical nucleation-growth mechanism and the micro/nanostructures-formation process are determined. Display Omitted - Highlights: • Micro/nanostructured Zn films have been electrodeposited directly from ZnO precursor in deep eutectic solvent (DES). • The morphology of the Zn electrodeposits depends on the cathodic potential and temperature. • The electrodeposited Zn films exhibit homogeneous morphologies with controllable particle sizes and improved corrosion resistance. • Cu–Zn alloy films have also been electrodeposited directly from their metal oxides precursors in DES. - Abstract: The electrodeposition of Zn and Cu–Zn alloy has been investigated in choline chloride (ChCl)/urea (1:2 molar ratio) based deep eutectic solvent (DES). Cyclic voltammetry study demonstrates that the reduction of Zn(II) to Zn is a diffusion-controlled quasi-reversible, one-step, two electrons transfer process. Chronoamperometric investigation indicates that the electrodeposition of Zn on a Cu electrode typically involves three-dimensional instantaneous nucleation with diffusion-controlled growth process. Micro/nanostructured Zn films can be obtained by controlling the electrodeposition potential and temperature. The electrodeposited Zn crystals preferentially orient parallel to the (101) plane. The Zn films electrodeposited under more positive potentials and low temperatures exhibit improved corrosion resistance in 3 wt% NaCl solution. In addition, Cu–Zn alloy films have also been electrodeposited directly from CuO–ZnO precursors in ChCl/urea-based DES. The XRD analysis indicates that the phase composition of the electrodeposited Cu–Zn alloy depends on the electrodeposition potential.

Preparation of a ceramic superconductor from ultrafine particles by freeze-dry process in Ba-Y-Cu-O system

International Nuclear Information System (INIS)

Chen Zuyao; Qian Yitai; Wan Yanjian; Rong Jingfang; Zhang Han; Pan Guoqiang; Zhao Yong; Zhang Qirui

1989-01-01

Freeze-dry technique is first reported for preparing ceramic ultrafines. The single-phase complex oxide Ba 2 YCu 3 O/sub 9-δ/, a poly-crystallized compound, and ceramic superconductor have been synthesized successfully. The experimental results show that not only is the ceramic superconductor obtained uniform with fine particles and excellent superconductivity, but the conditions for solid reactions are relatively limited

Relationships between molecular structure and kinetic and thermodynamic controls in lipid systems. Part III. Crystallization and phase behavior of 1-palmitoyl-2,3-stearoyl-sn-glycerol (PSS) and tristearoylglycerol (SSS) binary system.

Science.gov (United States)

Bouzidi, Laziz; Narine, Suresh S

2012-01-01

The phase behavior of 1-palmitoyl-2,3-distearoyl-sn-glycerol (PSS)/tristearoylglycerol (SSS) binary system was investigated in terms of polymorphism, crystallization and melting behavior, microstructure and solid fat content (SFC) using widely different constant cooling rates. Kinetic phase diagrams were experimentally determined from the DSC heating thermograms and analyzed using a thermodynamic model to account for non-ideality of mixing. The kinetic phase diagram presented a typical eutectic behavior with a eutectic point at the 0.5(PSS) mixture with a probable precipitation line from 0.5(PSS) to 1.0(PSS), regardless of the rate at which the sample was cooled. The eutectic temperature decreased only slightly with increasing cooling rate. PSS has a strong effect on the physical properties of the PSS-SSS mixtures. In fact, the overall phase behavior of the PSS-SSS binary system was determined, for a very large part, by the asymmetrical TAG. Moreover, PSS is a key driver of the high stability observed in crystal growth, polymorphism and phase development. Levels as low as 10% PSS, when cooled slowly, and 30% when cooled rapidly, were found to be sufficient to suppress the effect of thermal processing. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Phase field simulations of ice crystal growth in sugar solutions

NARCIS (Netherlands)

Sman, Van Der R.G.M.

2016-01-01

We present the first model ever, that describes explicitly ice crystal growth in a sugar solution during freezing. This 2-D model uses the phase field method, supplemented with realistic, and predictive theories on the thermodynamics and (diffusion) kinetics of this food system. We have to make

Effect of magnetic field on food freezing

OpenAIRE

村田, 圭治; 奥村, 太一; 荒賀, 浩一; 小堀, 康功

2010-01-01

[Abstract] This paper presents an experimental investigation on effects of magnetic field on food freezing process. Although purpose of food freezing is to suppress the deterioration of food, freezing breaks food tissue down, and some nutrient and delicious element flow out after thawing. Recently, a few of refrigeration equipments with electric and magnetic fields have attracted attention from food production companies and mass media. Water and tuna were freezed in magnetic field (100kH, 1.3...

Divorced Eutectic Solidification of Mg-Al Alloys

Science.gov (United States)

Monas, Alexander; Shchyglo, Oleg; Kim, Se-Jong; Yim, Chang Dong; Höche, Daniel; Steinbach, Ingo

2015-08-01

We present simulations of the nucleation and equiaxed dendritic growth of the primary hexagonal close-packed -Mg phase followed by the nucleation of the -phase in interdendritic regions. A zoomed-in region of a melt channel under eutectic conditions is investigated and compared with experiments. The presented simulations allow prediction of the final properties of an alloy based on process parameters. The obtained results give insight into the solidification processes governing the microstructure formation of Mg-Al alloys, allowing their targeted design for different applications.

Magnetic, electrical and optical properties of liquid crystals

International Nuclear Information System (INIS)

Florea, S.C.

1980-01-01

This thesis lays stress on the study of thermotrop nematic liquid crystals. But the crystals whose mesomorphism is achieved by an increase and decrease in temperature and the crystal category exhibiting a mesomorphism in a deep freezing phase are also studied. The results of the research carried out in the laboratory of ''active media, lasers and matter-radiation interactions'' of the Institute for Physics and Technology of Radiation Apparata as well as in the laboratories of liquid crystals and nuclear magnetic resonance of the Polytechnical Institute of Bucharest during seven years have had in view two main objectives: to elucidate and prove experimentally a new mechanism of nuclear relaxation in liquid crystals, proposed by the author; to use the current experimental techniques and methods applied in the above-mentioned laboratories to characterize and test some foreign mesomorphic media which are synthesized locally, providing a wide range of applications, such as colour television. (author)

Freezing of Lennard-Jones-type fluids

International Nuclear Information System (INIS)

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

2011-01-01

We put forward an approximate method to locate the fluid-solid (freezing) phase transition in systems of classical particles interacting via a wide range of Lennard-Jones-type potentials. This method is based on the constancy of the properly normalized second derivative of the interaction potential (freezing indicator) along the freezing curve. As demonstrated recently it yields remarkably good agreement with previous numerical simulation studies of the conventional 12-6 Lennard-Jones (LJ) fluid [S.A.Khrapak, M.Chaudhuri, G.E.Morfill, Phys. Rev. B 134, 052101 (2010)]. In this paper, we test this approach using a wide range of the LJ-type potentials, including LJ n-6 and exp-6 models, and find that it remains sufficiently accurate and reliable in reproducing the corresponding freezing curves, down to the triple-point temperatures. One of the possible application of the method--estimation of the freezing conditions in complex (dusty) plasmas with ''tunable'' interactions--is briefly discussed.

Dimethylurea/citric acid as a highly efficient deep eutectic solvent

Indian Academy of Sciences (India)

Dimethylurea/citric acid deep eutectic solvent was used as a dual catalyst and a green reaction medium for the efficient synthesis of bis(indolyl)methanes, quinolines and aryl-4, 5-diphenyl-1H-imidazoles. Ease of recovery and reusability of DES with high activity makes this method efficient and eco-friendly.

Investigation of freeze concentration as a process for industrial energy conservation in black liquor, acetic acid, and citrus juice applications. Final report

Energy Technology Data Exchange (ETDEWEB)

None

1979-07-01

One of the largest consumers of energy in industrial processing is the equipment that concentrates weak aqueous solutions to stronger more sellable or reusable concentrations. The technical and economic feasibility of applying freeze concentration (that is, crystallization and removal from solution of pure solvent - water) as an alternative to heat evaporation (or distillation) to three industrial applications is established. For each of the applications - pulp mill black liquor concentration, acetic acid recovery and orange juice concentration - the economic analyses indicate that the energy savings achievable by freezing justify the respective capital investments with pay out periods of generally one to three years. Past freeze concentration operations have been in the 10,000 to 100,000 gallons per day range for sea water desalination. Research and development work will be required to adapt this work to the three industrial applications.

Freeze-thaw durability of air-entrained concrete.

Science.gov (United States)

Shang, Huai-Shuai; Yi, Ting-Hua

2013-01-01

One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles). The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss) and internal crack growth (characterized by the loss of dynamic modulus of elasticity). The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to "the test method of long-term and durability on ordinary concrete" GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

Momentum anisotropy at freeze out

International Nuclear Information System (INIS)

Feld, S.; Borghini, N.; Lang, C.

2017-01-01

The transition from a hydrodynamical modeling to a particle-based approach is a crucial element of the description of high-energy heavy-ion collisions. Assuming this “freeze out” happens instantaneously at each point of the expanding medium, we show that the local phase-space distribution of the emitted particles is asymmetric in momentum space. This suggests the use of anisotropic hydrodynamics for the last stages of the fluid evolution. We discuss how observables depend on the amount of momentum-space anisotropy at freeze out and how smaller or larger anisotropies allow for different values of the freeze-out temperature. (paper)

Bulk water freezing dynamics on superhydrophobic surfaces

Science.gov (United States)

Chavan, S.; Carpenter, J.; Nallapaneni, M.; Chen, J. Y.; Miljkovic, N.

2017-01-01

In this study, we elucidate the mechanisms governing the heat-transfer mediated, non-thermodynamic limited, freezing delay on non-wetting surfaces for a variety of characteristic length scales, Lc (volume/surface area, 3 mm commercial superhydrophobic spray coatings, showing a monotonic increase in freezing time with coating thickness. The added thermal resistance of thicker coatings was much larger than that of the nanoscale superhydrophobic features, which reduced the droplet heat transfer and increased the total freezing time. Transient finite element method heat transfer simulations of the water slab freezing process were performed to calculate the overall heat transfer coefficient at the substrate-water/ice interface during freezing, and shown to be in the range of 1-2.5 kW/m2K for these experiments. The results shown here suggest that in order to exploit the heat-transfer mediated freezing delay, thicker superhydrophobic coatings must be deposited on the surface, where the coating resistance is comparable to the bulk water/ice conduction resistance.

A Sustainable Redox-Flow Battery with an Aluminum-Based, Deep-Eutectic-Solvent Anolyte.

Science.gov (United States)

Zhang, Changkun; Ding, Yu; Zhang, Leyuan; Wang, Xuelan; Zhao, Yu; Zhang, Xiaohong; Yu, Guihua

2017-06-19

Nonaqueous redox-flow batteries are an emerging energy storage technology for grid storage systems, but the development of anolytes has lagged far behind that of catholytes due to the major limitations of the redox species, which exhibit relatively low solubility and inadequate redox potentials. Herein, an aluminum-based deep-eutectic-solvent is investigated as an anolyte for redox-flow batteries. The aluminum-based deep-eutectic solvent demonstrated a significantly enhanced concentration of circa 3.2 m in the anolyte and a relatively low redox potential of 2.2 V vs. Li + /Li. The electrochemical measurements highlight that a reversible volumetric capacity of 145 Ah L -1 and an energy density of 189 Wh L -1 or 165 Wh kg -1 have been achieved when coupled with a I 3 - /I - catholyte. The prototype cell has also been extended to the use of a Br 2 -based catholyte, exhibiting a higher cell voltage with a theoretical energy density of over 200 Wh L -1 . The synergy of highly abundant, dendrite-free, multi-electron-reaction aluminum anodes and environmentally benign deep-eutectic-solvent anolytes reveals great potential towards cost-effective, sustainable redox-flow batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Applicable technical method for freeze-substitution of high pressure ...

African Journals Online (AJOL)

bmshsj

2011-11-02

Quintana, 1994) are available for the microscopic visualization of intracellular organelles. Cryo- fixation, plunge freezing, propane jet freezing, cold metal block freezing, and high pressure freezing provide advantages over chemical ...

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.

Optimization of a pharmaceutical freeze-dried product and its process using an experimental design approach and innovative process analyzers.

Science.gov (United States)

De Beer, T R M; Wiggenhorn, M; Hawe, A; Kasper, J C; Almeida, A; Quinten, T; Friess, W; Winter, G; Vervaet, C; Remon, J P

2011-02-15

The aim of the present study was to examine the possibilities/advantages of using recently introduced in-line spectroscopic process analyzers (Raman, NIR and plasma emission spectroscopy), within well-designed experiments, for the optimization of a pharmaceutical formulation and its freeze-drying process. The formulation under investigation was a mannitol (crystalline bulking agent)-sucrose (lyo- and cryoprotector) excipient system. The effects of two formulation variables (mannitol/sucrose ratio and amount of NaCl) and three process variables (freezing rate, annealing temperature and secondary drying temperature) upon several critical process and product responses (onset and duration of ice crystallization, onset and duration of mannitol crystallization, duration of primary drying, residual moisture content and amount of mannitol hemi-hydrate in end product) were examined using a design of experiments (DOE) methodology. A 2-level fractional factorial design (2(5-1)=16 experiments+3 center points=19 experiments) was employed. All experiments were monitored in-line using Raman, NIR and plasma emission spectroscopy, which supply continuous process and product information during freeze-drying. Off-line X-ray powder diffraction analysis and Karl-Fisher titration were performed to determine the morphology and residual moisture content of the end product, respectively. In first instance, the results showed that - besides the previous described findings in De Beer et al., Anal. Chem. 81 (2009) 7639-7649 - Raman and NIR spectroscopy are able to monitor the product behavior throughout the complete annealing step during freeze-drying. The DOE approach allowed predicting the optimum combination of process and formulation parameters leading to the desired responses. Applying a mannitol/sucrose ratio of 4, without adding NaCl and processing the formulation without an annealing step, using a freezing rate of 0.9°C/min and a secondary drying temperature of 40°C resulted in

TEM microstructural analysis of creep deformed CM186LC single crystal Ni-base superalloy

Energy Technology Data Exchange (ETDEWEB)

Dubiel, B.; Czyrska-Filemonowicz, A. [AGH Univ. of Science and Technology, Krakow (Poland); Blackler, M. [Howmet Ltd., Exeter (United Kingdom); Barnard, P.M. [ALSTOM Power Turbo-Systems Technology Centre, Rugby (United Kingdom)

2006-07-01

The nickel based single crystal superalloy CM186LC was extensively investigated as a potential low cost material for industrial gas turbine vanes within the COST522 programme. The alloy exhibits inhomogeneous structure consisting of dendritic regions and eutectic colonies. In the present work attention is focused on microstructural changes observed in single crystal CM186LC following creep deformation at 750 C. Creep tests were conducted at 750 C with an applied stress of 560 or 675 MPa for up to 11440 hours. The microstructure o ruptured and terminated specimens was investigated by scanning (SEM) and transmission (TEM) electron microscopy. TEM analysis revealed the microstructural changes in the CM186LC at primary and secondary creep as well as after creep rupture. (orig.)

Pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} on amorphous dielectric layers towards monolithic 3D photonic integration

Energy Technology Data Exchange (ETDEWEB)

Li, Haofeng; Brouillet, Jeremy; Wang, Xiaoxin; Liu, Jifeng, E-mail: Jifeng.Liu@dartmouth.edu [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States)

2014-11-17

We demonstrate pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} crystallized on amorphous layers at <450 °C towards 3D Si photonic integration. We developed two approaches to seed the lateral single crystal growth: (1) utilize the Gibbs-Thomson eutectic temperature depression at the tip of an amorphous GeSn nanotaper for selective nucleation; (2) laser-induced nucleation at one end of a GeSn strip. Either way, the crystallized Ge{sub 0.89}Sn{sub 0.11} is dominated by a single grain >18 μm long that forms optoelectronically benign twin boundaries with others grains. These pseudo single crystal, direct-band-gap Ge{sub 0.89}Sn{sub 0.11} patterns are suitable for monolithic 3D integration of active photonic devices on Si.

Cryopreservation of boar semen. III: Ultrastructure of boar spermatozoa frozen ultra-rapidly at various stages of conventional freezing and thawing.

Science.gov (United States)

Bwanga, C O; Ekwall, H; Rodriguez-Martinez, H

1991-01-01

Ejaculated boar spermatozoa subjected to a conventional freezing and thawing process, were ultra-rapidly fixed, freeze-substituted and examined by electron microscopy to monitor the presence of real or potential intracellular ice and the degree of cell protection attained with the different extenders used during the process. Numerous ice crystal marks representing the degree of hydration of the cells were located in the perinuclear space of those spermatozoa not in proper contact with the extender containing glycerol (i.e. prior to freezing). The spermatozoa which were in proper contact with the extenders presented a high degree of preservation of the acrosomes, plasma membranes as well as the nuclear envelopes. No ice marks were detected in acrosomes before thawing, indicating that the conventional assayed cryopreservation method provided a good protection against cryoinjury. The presence of acrosomal changes (internal vesiculization, hydration and swelling) in thawed samples however, raises serious questions about the thawing procedure employed.

A new approach to study interaction parameters in cyanobiphenyl liquid crystal binary systems

International Nuclear Information System (INIS)

Javadian, Soheila; Dalir, Nima; Gilani, Ali Ghanadzadeh; Kakemam, Jamal; Yousefi, Ali

2015-01-01

Highlights: • The phase transition of 7CB and 5CB liquid crystals studied using the DSC. • This work includes the determination of the eutectic in the 7CB/5CB mixture. • The excess functions and interaction parameters calculated in the 7CB/5CB mixtures. • The P ∗ randomicity parameter used to describe the phase transitions of C–N and N–I. • A small amount of P ∗ showed a non-random identity of the C–N phase transition. - Abstract: The phase transition of heptylcyanobiphenyl 7CB and pentylcyanobiphenyl 5CB liquid crystals was investigated using the differential scanning calorimetry DSC technique. Then, the phase transition of different compositions of 7CB/5CB binary mixture was studied to determine the eutectic point. The phase diagram of mentioned binary system in 7CB mole fraction of 0.45 at T = 273.45 K is in good agreement with that of predicted from Schroder–van Laar equation. The thermodynamic excess functions and interaction parameters were calculated to describe the phase transition physically using the non-random mixing for the first time. The P ∗ randomicity parameter was used to describe the phase transitions of C–N and N–I in which a small amount of P ∗ shows a non-random identity of C–N phase transition. Contrarily, the P ∗ is greater in N–I phase transition showing a random mixing process

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...

Ice Nucleation of Soot Particles in the Cirrus Regime: Is Pore Condensation and Freezing Relevant for Soot?

Science.gov (United States)

Kanji, Z. A.; Mahrt, F.; David, R.; Marcolli, C.; Lohmann, U.; Fahrni, J.; Brühwiler, D.

2017-12-01

Heterogeneous ice nucleation (HIN) onto soot particles from previous studies have produced inconsistent results of temperature and relative humidity conditions required for freezing depending on the source of soot particle investigated. The ability of soot to act as HIN depended on the type of soot and size of particle. Often homogenous freezing conditions or water saturation conditions were required to freeze soot particles, rendering HIN irrelevant. Using synthesised mesoporous silica particles, we show pore condensation and freezing works with experiments performed in the Zurich Ice Nucleation Chamber (ZINC). By testing a variety of soot particles in parallel in the Horizontal Ice Nucleation Chamber (HINC), we suggest that previously observed HIN on soot particles is not the responsible mechanism for ice formation. Laboratory generated CAST brown and black soot, commercially available soot and acid treated soot were investigated for their ice nucleation abilities in the mixed-phase and cirrus cloud temperature regimes. No heterogeneous ice nucleation activity is inferred at T > -38 °C (mixed-phase cloud regime), however depending on particle size and soot type, HIN was observed for T nucleation of ice in the pores or cavities that are ubiquitous in soot particles between the primary spherules. The ability of some particles to freeze at lower relative humidity compared to others demonstrates why hydrophobicity plays a role in ice nucleation, i.e. controlling the conditions at which these cavities fill with water. Thus for more hydrophobic particles pore filling occurs at higher relative humidity, and therefore freezing of pore water and ice crystal growth. Future work focusses on testing the cloud processing ability of soot particles and water adsorption isotherms of the different soot samples to support the hydrophobicity inferences from the ice nucleation results.

Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4

Science.gov (United States)

Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

2013-10-01

A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min.

Freeze dehydration of milk using microwave energy

International Nuclear Information System (INIS)

Souda, K.B.; Akyel, C.; Bilgen, E.

1989-01-01

This paper presents the results of experimental studies on heat and mass transfer during a microwave freeze dehydration process. An experimental system and procedure was developed to freeze dry milk. A 2500-W microwave system with an appropriate wave guide was set up and instrumented, and a procedure was experimentally developed to obtain milk powder first by freezing milk and then dehydrating it at low pressure using microwave energy. An unsteady-state analysis was used to derive a one-dimensional mathematical model of the freeze dehydration process in a microwave electromagnetic field

Freeze-Thaw Durability of Air-Entrained Concrete

Directory of Open Access Journals (Sweden)

Huai-Shuai Shang

2013-01-01

Full Text Available One of the most damaging actions affecting concrete is the abrupt temperature change (freeze-thaw cycles. The types of deterioration of concrete structures by cyclic freeze-thaw can be largely classified into surface scaling (characterized by the weight loss and internal crack growth (characterized by the loss of dynamic modulus of elasticity. The present study explored the durability of concrete made with air-entraining agent subjected to 0, 100, 200, 300, and 400 cycles of freeze-thaw. The experimental study of C20, C25, C30, C40, and C50 air-entrained concrete specimens was completed according to “the test method of long-term and durability on ordinary concrete” GB/T 50082-2009. The dynamic modulus of elasticity and weight loss of specimens were measured after different cycles of freeze-thaw. The influence of freeze-thaw cycles on the relative dynamic modulus of elasticity and weight loss was analyzed. The findings showed that the dynamic modulus of elasticity and weight decreased as the freeze-thaw cycles were repeated. They revealed that the C30, C40, and C50 air-entrained concrete was still durable after 300 cycles of freeze-thaw according to the experimental results.

A Theory of Immersion Freezing

Science.gov (United States)

Barahona, Donifan

2017-01-01

Immersion freezing is likely involved in the initiation of precipitation and determines to large extent the phase partitioning in convective clouds. Theoretical models commonly used to describe immersion freezing in atmospheric models are based on the classical nucleation theory which however neglects important interactions near the immersed particle that may affect nucleation rates. This work introduces a new theory of immersion freezing based on two premises. First, immersion ice nucleation is mediated by the modification of the properties of water near the particle-liquid interface, rather than by the geometry of the ice germ. Second, the same mechanism that leads to the decrease in the work of germ formation also decreases the mobility of water molecules near the immersed particle. These two premises allow establishing general thermodynamic constraints to the ice nucleation rate. Analysis of the new theory shows that active sites likely trigger ice nucleation, but they do not control the overall nucleation rate nor the probability of freezing. It also suggests that materials with different ice nucleation efficiency may exhibit similar freezing temperatures under similar conditions but differ in their sensitivity to particle surface area and cooling rate. Predicted nucleation rates show good agreement with observations for a diverse set of materials including dust, black carbon and bacterial ice nucleating particles. The application of the new theory within the NASA Global Earth System Model (GEOS-5) is also discussed.

Why do ultrasoft repulsive particles cluster and crystallize? Analytical results from density-functional theory.

Science.gov (United States)

Likos, Christos N; Mladek, Bianca M; Gottwald, Dieter; Kahl, Gerhard

2007-06-14

We demonstrate the accuracy of the hypernetted chain closure and of the mean-field approximation for the calculation of the fluid-state properties of systems interacting by means of bounded and positive pair potentials with oscillating Fourier transforms. Subsequently, we prove the validity of a bilinear, random-phase density functional for arbitrary inhomogeneous phases of the same systems. On the basis of this functional, we calculate analytically the freezing parameters of the latter. We demonstrate explicitly that the stable crystals feature a lattice constant that is independent of density and whose value is dictated by the position of the negative minimum of the Fourier transform of the pair potential. This property is equivalent with the existence of clusters, whose population scales proportionally to the density. We establish that regardless of the form of the interaction potential and of the location on the freezing line, all cluster crystals have a universal Lindemann ratio Lf=0.189 at freezing. We further make an explicit link between the aforementioned density functional and the harmonic theory of crystals. This allows us to establish an equivalence between the emergence of clusters and the existence of negative Fourier components of the interaction potential. Finally, we make a connection between the class of models at hand and the system of infinite-dimensional hard spheres, when the limits of interaction steepness and space dimension are both taken to infinity in a particularly described fashion.

Lauric and palmitic acids eutectic mixture as latent heat storage material for low temperature heating applications

International Nuclear Information System (INIS)

Tuncbilek, Kadir; Sari, Ahmet; Tarhan, Sefa; Erguenes, Gazanfer; Kaygusuz, Kamil

2005-01-01

Palmitic acid (PA, 59.8 deg. C) and lauric acid (LA, 42.6 deg. C) are phase change materials (PCM) having quite high melting temperatures which can limit their use in low temperature solar applications such as solar space heating and greenhouse heating. However, their melting temperatures can be tailored to appropriate value by preparing a eutectic mixture of the lauric and the palmitic acids. In the present study, the thermal analysis based on differential scanning calorimetry (DSC) technique shows that the mixture of 69.0 wt% LA and 31 wt% PA forms a eutectic mixture having melting temperature of 35.2 deg. C and the latent heat of fusion of 166.3 J g -1 . This study also considers the experimental determination of the thermal characteristics of the eutectic mixture during the heat charging and discharging processes. Radial and axial temperature distribution, heat transfer coefficient between the heat transfer fluid (HTF) pipe and the PCM, heat recovery rate and heat charging and discharging fractions were experimentally established employing a vertical concentric pipe-in-pipe energy storage system. The changes of these characteristics were evaluated with respect to the effect of inlet HTF temperature and mass flow rate. The DSC thermal analysis and the experimental results indicate that the LA-PA eutectic mixture can be a potential material for low temperature thermal energy storage applications in terms of its thermo-physical and thermal characteristics

Freezing tolerance of conifer seeds and germinants.

Science.gov (United States)

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

2003-12-01

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

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

Purpose Isomalt is a sugar alcohol used as an excipient in commercially available solid oral dosage forms. The potential of isomalt as a novel freeze-drying excipient was studied in order to increase knowledge of the behavior of isomalt when it is freeze-dried. Methods Isomalt was freeze-dried in......Purpose Isomalt is a sugar alcohol used as an excipient in commercially available solid oral dosage forms. The potential of isomalt as a novel freeze-drying excipient was studied in order to increase knowledge of the behavior of isomalt when it is freeze-dried. Methods Isomalt was freeze......-dried in four different diastereomer compositions and its physical stability was investigated with differential scanning calorimetry, Fourier-transform infrared and Raman spectroscopy, X-ray powder diffraction, Karl-Fischer titration and thermogravimetric analysis in order to verify the solid state form...... 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...

Sintering, consolidation, reaction and crystal growth by the spark plasma system (SPS)

Energy Technology Data Exchange (ETDEWEB)

Omori, M. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research

2000-08-15

The graphite die set in spark plasma system (SPS) is heated by a pulse direct current. Weak plasma, discharge impact, electric field and electric current, which are based on this current, induce good effects on materials in the die. The surface films of aluminum and pure WC powders are ruptured by the spark plasma. Pure AlN powder is sintered without sintering additives in the electric field. The spark plasma leaves discharge patterns on insulators. Organic fibers are etched by the spark plasma. Thermosetting polyimide is consolidated by the spark plasma. Insoluble polymonomethylsilane is rearranged into the soluble one by the spark plasma. A single crystal of CoSb{sub 3} is grown from the compound powders in the electric field by slow heating. Coupled crystals of eutectic powder are connected with each other in the electric field. (orig.)

Metallurgical Parameters Controlling the Eutectic Silicon Charateristics in Be-Treated Al-Si-Mg Alloys.

Science.gov (United States)

Ibrahim, Mohamed F; Elgallad, Emad M; Valtierra, Salvador; Doty, Herbert W; Samuel, Fawzy H

2016-01-27

The present work was carried out on Al-7%Si-0.4%Mg-X alloy (where X = Mg, Fe, Sr or Be), where the effect of solidification rate on the eutectic silicon characteristics was investigated. Two solidification rates corresponding to dendrite arm spacings (DAS) of 24 and 65 μm were employed. Samples with 24 μm DAS were solution heat-treated at 540 °C for 5 and 12 h prior to quenching in warm water at 65 °C. Eutectic Si particle charateristics were measured using an image analyzer. The results show that the addition of 0.05% Be leads to partial modification of the Si particles. Full modification was only obtained when Sr was added in an amount of 150-200 ppm, depending on the applied solidification rate. Increasing the amount of Mg to 0.8% in Sr-modified alloys leads to a reduction in the effectiveness of Sr as the main modifier. Similar observations were made when the Fe content was increased in Be-treated alloys due to the Be-Fe interaction. Over-modification results in the precipitation of hard Sr-rich particles, mainly Al₄SrSi₂, whereas overheating causes incipient melting of the Al-Cu eutectic and hence the surrounding matrix. Both factors lead to a deterioration in the alloy mechanical properties. Furthermore, the presence of long, acicular Si particles accelerates the occurrence of fracture and, as a result, yields poor ductility. In low iron (less than 0.1 wt%) Al-Si-Mg alloys, the mechanical properties in the as cast, as well as heat treated conditions, are mainly controlled by the eutectic Si charatersitics. Increasing the iron content and, hence, the volume fraction of Fe-based intermetallics leads to a complex fracture mode.

Metallurgical Parameters Controlling the Eutectic Silicon Charateristics in Be-Treated Al-Si-Mg Alloys

Directory of Open Access Journals (Sweden)

Mohamed F. Ibrahim

2016-01-01

Full Text Available The present work was carried out on Al-7%Si-0.4%Mg-X alloy (where X = Mg, Fe, Sr or Be, where the effect of solidification rate on the eutectic silicon characteristics was investigated. Two solidification rates corresponding to dendrite arm spacings (DAS of 24 and 65 μm were employed. Samples with 24 μm DAS were solution heat-treated at 540 °C for 5 and 12 h prior to quenching in warm water at 65 °C. Eutectic Si particle charateristics were measured using an image analyzer. The results show that the addition of 0.05% Be leads to partial modification of the Si particles. Full modification was only obtained when Sr was added in an amount of 150–200 ppm, depending on the applied solidification rate. Increasing the amount of Mg to 0.8% in Sr-modified alloys leads to a reduction in the effectiveness of Sr as the main modifier. Similar observations were made when the Fe content was increased in Be-treated alloys due to the Be-Fe interaction. Over-modification results in the precipitation of hard Sr-rich particles, mainly Al4SrSi2, whereas overheating causes incipient melting of the Al-Cu eutectic and hence the surrounding matrix. Both factors lead to a deterioration in the alloy mechanical properties. Furthermore, the presence of long, acicular Si particles accelerates the occurrence of fracture and, as a result, yields poor ductility. In low iron (less than 0.1 wt% Al-Si-Mg alloys, the mechanical properties in the as cast, as well as heat treated conditions, are mainly controlled by the eutectic Si charatersitics. Increasing the iron content and, hence, the volume fraction of Fe-based intermetallics leads to a complex fracture mode.

Phase-field-lattice Boltzmann study for lamellar eutectic growth in a natural convection melt

Directory of Open Access Journals (Sweden)

Ang Zhang

2017-11-01

Full Text Available In the present study, the influence of natural convection on the lamellar eutectic growth is determined by a phase-field-lattice Boltzmann study for Al-Cu eutectic alloy. The mass difference resulting from concentration difference led to the fluid flow, and a robust parallel and adaptive mesh refinement algorithm was employed to improve the computational efficiency without any compromising accuracy. Results show that the existence of natural convection would affect the growth undercooling and thus control the interface shape by adjusting the lamellar width. In particular, by alternating the magnitude of the solute expansion coefficient, the strength of the natural convection is changed. Corresponding microstructure patterns are discussed and compared with those under no-convection conditions.

Crystal growth and magnetic property of a new compound CeAu4Si2

International Nuclear Information System (INIS)

Nakashima, Hiroshi; Thamizhavel, Arumugam; Matsuda, Tatsuma D.; Haga, Yoshinori; Takeuchi, Tetsuya; Sugiyama, Kiyohiro; Settai, Rikio; Onuki, Yoshichika

2006-01-01

We have succeeded in growing a new ternary Ce compound CeAu 4 Si 2 . This compound crystallizes in the tetragonal crystal structure P4-bar m2 (-bar 1-bar 1-bar 5) with lattice parameters a=4.3304 -bar A and c=27.409 -bar A. The local environment around Ce atoms is similar to that of the well-known ThCr 2 Si 2 -type tetragonal structure in CeAu 2 Si 2 . Single crystals of CeAu 4 Si 2 were grown by the flux method using an Au 4.37 Si eutectic alloy as flux. Electrical resistivity, specific heat and magnetization measurements revealed a ferromagnetic ordering at T C =5.3 -bar K with a saturation moment of 1.7-bar μ B /Ce. Anisotropic features in the magnetic susceptibility and magnetization were well explained by a crystalline electric field (CEF) model. Estimated excitation energies from the ground state doublet to two excited doublets are 284 and 340-bar K, respectively

Vacuum distillation for the separation of LiCl-KCl eutectic salt and cadmium in pyro process

International Nuclear Information System (INIS)

Kwon, S. W.; Park, K. M.; Lee, S. J.; Park, S. B.; Woo, M. S.; Kim, K. R.; Kim, J. G.; Ahn, D. H.; Lee, H. S.

2010-10-01

Electrorefining is a key step in pyro processing. Electrorefining process is generally composed of two recovery steps- a deposit of uranium onto a solid cathode (electrorefining) and then the recovery of the remaining uranium and Tru (Transuranic) elements simultaneously by a liquid cadmium cathode (electrowinning). In this study, distillation experiments of a LiCl-KCl eutectic salt and cadmium metal were carried out to examine the distillation behaviors for the development of the electrorefining and the electrowinning processes. The experimental set-up was composed of a distillation tower with an evaporator and a condenser, vacuum pump, control unit, and an off gas treatment system. The solid-liquid separation prior to distillation of the LiCl-KCl eutectic salt was proposed and found to be feasible for the reduction of the burden of the distillation process. The LiCl-KCl eutectic salt was successfully distilled after the liquid salt separation. Distillation experiments for cadmium metal were also carried out. The apparent evaporation rates of LiCl-KCl eutectic salt and cadmium increased with an increasing temperature. The evaporation behaviors of cadmium metal and cadmium-cerium alloy were compared. Cadmium in the alloy was successfully distilled and separated from cerium. The evaporation rate of cadmium in the alloy was lower than that of cadmium metal. The low evaporation rate of the alloy was probably caused by the formation of an intermetallic compound and the residual salt during the preparation of the alloy. Therefore, the distillation temperature for the distillation of the liquid cathode should be higher than the distillation of cadmium metal. The measured evaporation rates of the eutectic salt and cadmium were compared with the values calculated by a relation based on the kinetics of gases. The theoretical values of the evaporation rate calculated by the Hertz-Langmuir relation were higher than the experimental values. The deviations were compensated for

Freezing the Master Production Schedule Under Rolling Planning Horizons

OpenAIRE

V. Sridharan; William L. Berry; V. Udayabhanu

1987-01-01

The stability of the Master Production Schedule (MPS) is a critical issue in managing production operations with a Material Requirements Planning System. One method of achieving stability is to freeze some portion or all of the MPS. While freezing the MPS can limit the number of schedule changes, it can also produce an increase in production and inventory costs. This paper examines three decision variables in freezing the MPS: the freezing method, the freeze interval length, and the planning ...

Thermal properties and reliability of eutectic mixture of stearic acid-acetamide as phase change material for latent heat storage

International Nuclear Information System (INIS)

Ma, Guixiang; Han, Lipeng; Sun, Jinhe; Jia, Yongzhong

2017-01-01

Highlights: • The system of stearic acid-acetamide binary mixtures were studied as phase change material. • The eutectic mixtures featured low melting temperatures and high latent heats of fusion for latent heat storage. • Solid-liquid phase diagrams for the system were constructed. • Negligible change in stability after 500 heating/cooling cycles. - Abstract: The thermal properties and reliability of the stearic acid (SA) with acetamide (AC) binary mixture were characterized using differential scanning calorimetry (DSC), powder X-ray diffraction (XRD), thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR). The phase diagrams for the SA-AC binary mixture with AC in the metastable and the stable form were constructed. The eutectic system with stable AC is 0.604 mol fraction SA, and displayed a melting temperature (T m ) of 64.55 °C and latent heat of melting (ΔH m ) of 193.87 J·g −1 . The eutectic systems with metastable AC are 0.397 and 0.604 mol fraction SA. The melting temperatures are 62.23 °C and 62.54 °C, and latent heats of fusion are 222.10 J·g −1 and 194.28 J·g −1 , respectively. Following accelerated thermal cycling tests, TG and FT-IR analysis indicate that the eutectic mixture (χ SA = 0.397) with the metastable AC has good cyclic and thermal stability. The results show that the SA-AC eutectic mixture use as phase change material (PCM) possess good prospect for low temperature thermal energy storage (TES) applications.

Solar-assisted MED treatment of Eskom power station waste water

Science.gov (United States)

Roos, Thomas H.; Rogers, David E. C.; Gericke, Gerhard

2017-06-01

The comparative benefits of multi-effect distillation (MED) used in conjunction with Nano Filtration (NF), Reverse Osmosis (RO) and Eutectic Freeze Crystallization (EFC) are determined for waste water minimization for inland coal fired power stations for Zero Liquid Effluent Discharge (ZLED). A sequence of technologies is proposed to achieve maximal water recovery and brine concentration: NF - physico-chemical treatment - MED - EFC. The possibility of extending the concentration of RO reject arising from minewater treatment at the Lethabo power station with MED alone is evaluated with mineral formation modelling using the thermochemical modelling software Phreeq-C. It is shown that pretreatment is essential to extend the amount of water that can be recovered, and this can be beneficially supported by NF.

Free energy change of off-eutectic binary alloys on solidification

Science.gov (United States)

Ohsaka, K.; Trinh, E. H.; Lin, J.-C.; Perepezko, J. H.

1991-01-01

A formula for the free energy difference between the undercooled liquid phase and the stable solid phase is derived for off-eutectic binary alloys in which the equilibrium solid/liquid transition takes place over a certain temperature range. The free energy change is then evaluated numerically for a Bi-25 at. pct Cd alloy modeled as a sub-subregular solution.

The effect of water-soluble polymers on the microstructure and properties of freeze-cast alumina ceramics

Science.gov (United States)

Pekor, Christopher Michael

Porous ceramics can be divided into three separate classes based on their pore size: microporous ceramics with pores less than 2 nm, mesoporous ceramics with pores in the range of 2--50 nm and macroporous ceramics with pores that are greater than 50 nm. In particular, macroporous ceramics are used in a variety of applications such as refractories, molten metal filtration, diesel particulate filters, heterogeneous catalyst supports and biomedical scaffolds. Freeze casting is a novel method used to create macroporous ceramics. In this method growing ice crystals act as a template for the pores and are solidified, often directionally, through a ceramic dispersion and removed from the green body through a freeze drying procedure. This method has attracted some attention over the past few years due to its relative simplicity, flexibility and environmental friendliness. On top of this freeze casting is capable of producing materials with high pore volume fractions, which is an advantage over processing by packing and necking of particles, where the pore volume fraction is typically less than 50%. Many of the basic processing variables that affect the freeze cast microstructure, such as the temperature gradient, interfacial velocity and solid loading of the dispersion have been well established in the literature. On the other hand, areas such as the effect of additives on the microstructure and mechanical properties have not been covered in great detail. In this study the concept of constitutional supercooling from basic solidification theory is used to explain the effects of two water-soluble polymers, polyethylene glycol and polyvinyl alcohol, on the microstructure of freeze cast alumina ceramics. In addition, changes in the observed microstructure will be related to experimentally determined values of permeability and compressive strength.

Comparing contact and immersion freezing from continuous flow diffusion chambers

Directory of Open Access Journals (Sweden)

B. Nagare

2016-07-01

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

The influence of freezer storage of urine samples on the BONN-Risk-Index for calcium oxalate crystallization.

Science.gov (United States)

Laube, Norbert; Zimmermann, Diana J

2004-01-01

This study was performed to quantify the effect of a 1-week freezer storage of urine on its calcium oxalate crystallization risk. Calcium oxalate is the most common urinary stone material observed in urolithiasis patients in western and affluent countries. The BONN-Risk-Index of calcium oxalate crystallization risk in human urine is determined from a crystallization experiment performed on untreated native urine samples. We tested the influence of a 1-week freezing on the BONN-Risk-Index value as well as the effect of the sample freezing on the urinary osmolality. In vitro crystallization experiments in 49 native urine samples from stone-forming and non-stone forming individuals were performed in order to determine their calcium oxalate crystallization risk according to the BONN-Risk-Index approach. Comparison of the results derived from original sample investigations with those obtained from the thawed aliquots by statistical evaluation shows that i) no significant deviation from linearity between both results exists and ii) both results are identical by statistical means. This is valid for both, the BONN-Risk-Index and the osmolality data. The differences in the BONN-Risk-Index results of both procedures of BONN-Risk-Index determination, however, exceed the clinically acceptable difference. Thus, determination of the urinary calcium oxalate crystallization risk from thawed urine samples cannot be recommended.

Validated thermodynamic prediction of AlP and eutectic (Si) solidification sequence in Al-Si cast alloys

International Nuclear Information System (INIS)

Liang, S M; Schmid-Fetzer, R

2016-01-01

The eutectic microstructure in hypoeutectic Al-Si cast alloys is strongly influenced by AlP particles which are potent nuclei for the eutectic (Si) phase. The solidification sequence of AlP and (Si) phases is, thus, crucial for the nucleation of eutectic silicon with marked impact on its morphology. This study presents this interdependence between Si- and P-compositions, relevant for Al-Si cast alloys, on the solidification sequence of AlP and (Si). These data are predicted from a series of thermodynamic calculations. The predictions are based on a self-consistent thermodynamic description of the Al-Si-P ternary alloy system developed recently. They are validated by independent experimental studies on microstructure and undercooling in hypoeutectic Al-Si alloys. A constrained Scheil solidification simulation technique is applied to predict the undercooling under clean heterogeneous nucleation conditions, validated by dedicated experimental observations on entrained droplets. These specific undercooling values may be very large and their quantitative dependence on Si and P content of the Al alloy is presented. (paper)

Flux flow and proximity effects in aligned Pb--Cd eutectic lamellar structures

International Nuclear Information System (INIS)

Spencer, C.R.

1977-09-01

A high speed directional solidification technique was used to fabricate lamellar Pb-Cd and (Pb-Mg)--(Cd-Mg) superconductor-normal metal composites in which all the lamellae are oriented perpendicular to the broad surface of the sample. These lamellar composites are found to behave like a large number (approximately 1000) of superconducting-normal-superconducting junctions. For the Pb-Cd eutectic system, the critical current densities and critical fields have shown no dependence upon the lamellar periods between 1.0 and 3.1 microns. The critical current density of the aligned lamellar Pb-Cd structures was enhanced approximately 50% when compared to quenched eutectic alloy and to pure Pb. The superconducting transition temperature, T/sub c/, varies inversely with the square of the thickness of the superconducting material as expected from Ginzburg-Landau theory. Upon annealing, the Pb lamellae change from type II to type I superconductivity

Flux flow and proximity effects in aligned Pb--Cd eutectic lamellar structures

Energy Technology Data Exchange (ETDEWEB)

Spencer, C. R.

1977-09-01

A high speed directional solidification technique was used to fabricate lamellar Pb-Cd and (Pb-Mg)--(Cd-Mg) superconductor-normal metal composites in which all the lamellae are oriented perpendicular to the broad surface of the sample. These lamellar composites are found to behave like a large number (approximately 1000) of superconducting-normal-superconducting junctions. For the Pb-Cd eutectic system, the critical current densities and critical fields have shown no dependence upon the lamellar periods between 1.0 and 3.1 microns. The critical current density of the aligned lamellar Pb-Cd structures was enhanced approximately 50% when compared to quenched eutectic alloy and to pure Pb. The superconducting transition temperature, T/sub c/, varies inversely with the square of the thickness of the superconducting material as expected from Ginzburg-Landau theory. Upon annealing, the Pb lamellae change from type II to type I superconductivity.

Polyvinyl alcohol/chitosan/montmorillonite nanocomposites preparation by freeze/thaw cycles and characterization

Directory of Open Access Journals (Sweden)

Părpăriţă Elena

2014-12-01

Full Text Available Polyvinyl alcohol (PVA and chitosan (CS based hydrogels are often chosen to obtain hydrogels as being considered non-toxic for human body. The present study aims the preparation and physical chemical characterisation of hydrogels based PVA and CS by using an environmental friendly method i.e. freeze/thaw. In this method the only parameters affecting the hydrogels’ properties is the PVA concentration in solution, time and number of cycles of freezing / thawing. Repeated freezing and thawing cycles resulted in production of a highly elastic polyvinyl alcohol hydrogel with higher degree of crystallization. Adding chitosan in polyvinyl alcohol hydrogel is giving to the newly formed material, biocompatibility and antibacterial properties due to the free amino groups of chitosan. Higher mechanical and thermal characteristics of PVA/CS based hydrogels were obtained by addition of a small amount of inorganic nanoparticles (montmorillonite clay, C30B into the matrix (i.e. 1%. Scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, near-infrared chemical imaging spectroscopy (NI-CI, X-ray diffraction (XRD, thermogravimetric analysis (TG, swelling and rheological measurements were used to characterize the polyvinyl alcohol/chitosan/montmorillonite properties. The swelling degree increased with decreasing chitosan content in hydrogels and the variation is opposite in nanocomposites, decreasing after introducing the nanoclay. The swelling behaviour was influenced by the presence of the nanoparticles. The plasticizer effect of the nanoparticles was reflected by obtaining a more compact hydrogel network with higher mechanical and thermal properties. The proposed materials can be a promising alternative in biomedical applications

High electrical resistivity Nd-Fe-B die-upset magnet doped with eutectic DyF3–LiF salt mixture

Directory of Open Access Journals (Sweden)

K. M. Kim

2017-05-01

Full Text Available Nd-Fe-B-type die-upset magnet with high electrical resistivity was prepared by doping of eutectic DyF3–LiF salt mixture. Mixture of melt-spun Nd-Fe-B flakes (MQU-F: Nd13.6Fe73.6Co6.6Ga0.6B5.6 and eutectic binary (DyF3–LiF salt (25 mol% DyF3 – 75 mol% LiF was hot-pressed and then die-upset. By adding the eutectic salt mixture (> 4 wt%, electrical resistivity of the die-upset magnet was enhanced to over 400 μΩ.cm compared to 190 μΩ.cm of the un-doped magnet. Remarkable enhancement of the electrical resistivity was attributed to homogeneous and continuous coverage of the interface between flakes by the easily melted eutectic salt dielectric mixture. It was revealed that active substitution of the Nd atoms in neighboring flakes by the Dy atoms from the added (DyF3–LiF salt mixture had occurred during such a quick thermal processing of hot-pressing and die-upsetting. This Dy substitution led to coercivity enhancement in the die-upset magnet doped with the eutectic (DyF3–LiF salt mixture. Coercivity and remanence of the die-upset magnet doped with (DyF3–LiF salt mixture was as good as those of the DyF3-doped magnet.

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 be...

Growth and characterization of LiInSe2 single crystals

Science.gov (United States)

Ma, Tianhui; Zhu, Chongqiang; Lei, Zuotao; Yang, Chunhui; Sun, Liang; Zhang, Hongchen

2015-04-01

Large and crack-free LiInSe2 single crystals were obtained by the vertical gradient freezing method with adding a temperature oscillation technology in a two-zone furnace. X-ray diffraction data showed that the pure LiInSe2 compound was synthesized. The grown crystals had different color depending on melt composition. The atomic ratios of elements of LiInSe2 crystals were obtained by an Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), and the structural formula were calculated according to the relative contents of elements. The average absorption coefficients were estimated by using average reflection indices. The absorption coefficients of the thermal annealing samples are 0.6 cm-1 at 2-3 μm. The transparent range of our LiInSe2 crystals is from 0.6 μm to 13.5 μm.

Carbon dioxide solubilities in decanoic acid-based hydrophobic deep eutectic solvents

NARCIS (Netherlands)

Zubeir, Lawien F.; Van Osch, Dannie J.G.P.; Rocha, Marisa A.A.; Banat, Fawzi; Kroon, Maaike C.

2018-01-01

The solubility of CO2 in hydrophobic deep eutectic solvents (DESs) has been measured for the first time. Six different hydrophobic DESs are studied in the temperature range from 298 to 323 K and at CO2 pressures up to 2 MPa. The results are evaluated by comparing the solubility data with existing

Review of possible experiments in the eutectic growth and thermodiffusion fields

International Nuclear Information System (INIS)

Malmejac, Yves.

1976-01-01

The results now available from the SKYLAB and ASTP programmes give a clearer indication of the lines of the research to pursue in the years to come. The criteria necessary for the choice of experiments are analysed in the fields of eutectic solidification and diffusion along a temperature gradient in liquid alloys [fr

Laboratory Investigation of Contact Freezing and the Aerosol to Ice Crystal Transformation Process

Energy Technology Data Exchange (ETDEWEB)

Shaw, Raymond A. [Michigan Technological Univ., Houghton, MI (United States)

2014-10-28

This project has been focused on the following objectives: 1. Investigations of the physical processes governing immersion versus contact nucleation, specifically surface-induced crystallization; 2. Development of a quadrupole particle trap with full thermodynamic control over the temperature range 0 to –40 °C and precisely controlled water vapor saturation ratios for continuous, single-particle measurement of the aerosol to ice crystal transformation process for realistic ice nuclei; 3. Understanding the role of ice nucleation in determining the microphysical properties of mixed-phase clouds, within a framework that allows bridging between laboratory and field measurements.

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.

Deep eutectic solvents for highly efficient separations in oil and gas industries

NARCIS (Netherlands)

Warrag, S.E.E.; Peters, C.J.; Kroon, M.C.

2017-01-01

Deep eutectic solvents (DESs) have captured a great scientific attention as a new, ‘green’ and sustainable class of tailor-made solvents. DESs share many properties with ionic liquids (ILs) including low vapor pressure, wide liquid range, thermal stability, low flammability, and high solvation

Air-cooled steam condensers non-freeze warranties

Energy Technology Data Exchange (ETDEWEB)

Larinoff, M.W.

1995-09-01

What this paper is suggesting is the seller quote a condenser package with a LIMITED NON-FREEZE WARRANTY. Relieve the inexperienced buyer of the responsibility for selecting freeze protection design options. The seller cannot afford to over-design because of the added costs and the need for a competitive price. Yet he cannot under-design and allow the condenser tubes to freeze periodically and then pay the repair bills in accordance with the warranty.

Studies on SiC(p) reinforced Al-Al sub 3 Ni eutectic matrix composites

International Nuclear Information System (INIS)

Masrom, A.K.; Foo, L.C.; Ismail, A.B.

1996-01-01

An investigation on processing of Al-5.69wt% Ni eutectic with SiC particulate composites is reported. The intermetallic composites are prepared by elemental powder metallurgy route and sintered at two different temperatures, i.e., 600 degree C and 620 degree C. Results show that the metal matrix was Al-Al sub 3 Ni eutectic. The phase analysis by XRD identified the presence of Al sub 3 Ni and Al as dominant phases together with silicon and Al sub 4 C sub 3 phase as minor phases. The Al sub 4 C sub 3 and Si phases are formed during sintering due to SiC-Al interface reaction. SEM micrographs also reveal the formation of microvoid surrounding the SiC particle

Gypsum crystals observed in experimental and natural sea ice

Science.gov (United States)

Geilfus, N.-X.; Galley, R. J.; Cooper, M.; Halden, N.; Hare, A.; Wang, F.; Søgaard, D. H.; Rysgaard, S.

2013-12-01

gypsum has been predicted to precipitate in sea ice, it has never been observed. Here we provide the first report on gypsum precipitation in both experimental and natural sea ice. Crystals were identified by X-ray diffraction analysis. Based on their apparent distinguishing characteristics, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the "Gitterman pathway" where gypsum is predicted to precipitate. The occurrence of authigenic gypsum in sea ice during its formation represents a new observation of precipitate formation and potential marine deposition in polar seas.

Thermal energy storage using chloride salts and their eutectics

International Nuclear Information System (INIS)

Myers, Philip D.; Goswami, D. Yogi

2016-01-01

Achieving the goals of the U.S. Department of Energy (DOE) Sunshot initiative requires (1) higher operating temperatures for concentrating solar power (CSP) plants to increase theoretical efficiency, and (2) effective thermal energy storage (TES) strategies to ensure dispatchability. Current inorganic salt-based TES systems in large-scale CSP plants generally employ molten nitrate salts for energy storage, but nitrate salts are limited in application to lower temperatures—generally, below 600 °C. These materials are sufficient for parabolic trough power plants, but they are inadequate for use at higher temperatures. At the higher operating temperatures achievable in solar power tower-type CSP plants, chloride salts are promising candidates for application as TES materials, owing to their thermal stability and generally lower cost compared to nitrate salts. In light of this, a recent study was conducted, which included a preliminary survey of chloride salts and binary eutectic systems that show promise as high temperature TES media. This study provided some basic information about the salts, including phase equilibria data and estimates of latent heat of fusion for some of the eutectics. Cost estimates were obtained through a review of bulk pricing for the pure salts among various vendors. This review paper updates that prior study, adding data for additional salt eutectic systems obtained from the literature. Where possible, data are obtained from the thermodynamic database software, FactSage. Radiative properties are presented, as well, since at higher temperatures, thermal radiation becomes a significant mode of heat transfer. Material compatibility for inorganic salts is another important consideration (e.g., with regard to piping and/or containment), so a summary of corrosion studies with various materials is also presented. Lastly, cost data for these systems are presented, allowing for meaningful comparison among these systems and other materials for TES

PC-SAFT modeling of CO2 solubilities in hydrophobic deep eutectic solvents

NARCIS (Netherlands)

Dietz, C.H.J.T.; van Osch, D.J.G.P.; Kroon, M.C.; Sadowski, G.; van Sint Annaland, M.; Gallucci, F.; Zubeir, L.F.; Held, C.

2017-01-01

The PC-SAFT 'pseudo-pure' approach was used for the modeling of CO2 solubilities in various hydrophobic deep eutectic solvents (DESs) for the first time. Only liquid density data were used to obtain the segment number, the temperature-independent segment diameter and the dispersion-energy parameter,

Computational thermo-hydro-mechanics for freezing and thawing multiphase geological media in the finite deformation range

Science.gov (United States)

Sun, W.; Na, S.

2017-12-01

A stabilized thermo-hydro-mechanical (THM) finite element model is introduced to investigate the freeze-thaw action of frozen porous media in the finite deformation range. By applying the mixture theory, frozen soil is idealized as a composite consisting of three phases, i.e., solid grain, unfrozen water and ice crystal. A generalized hardening rule at finite strain is adopted to replicate how the elasto-plastic responses and critical state evolve under the influence of phase transitions and heat transfer. The enhanced particle interlocking and ice strengthening during the freezing processes and the thawing-induced consolidation at the geometrical nonlinear regimes are both replicated in numerical examples. The numerical issues due to lack of two-fold inf-sup condition and ill-conditioning of the system of equations are addressed. Numerical examples for engineering applications at cold region are analyzed via the proposed model to predict the impacts of changing climate on infrastructure at cold regions.

Application of the rotating cylinder electrode in molten LiCl-KCl eutectic containing uranium(III)- and magnesium(II)-chloride

Energy Technology Data Exchange (ETDEWEB)

Rappleye, Devin, E-mail: rappleye1@llnl.gov; Simpson, Michael F.

2017-04-15

The application of the rotating cylinder electrode (RCE) to molten LiCl-KCl eutectic mixtures for electroanalytical measurements is presented. This enabled the measurement of the limiting current which was observed to follow a linear trend with the rotational rate raised to 0.64–0.65 power on average, which closely agrees with existing RCE mass-transfer correlations. This is the first publication of electroanalytical RCE measurements in LiCl-KCl eutectic based molten salt mixtures, to our knowledge. These measurements were made in mixtures of molten LiCl-KCl eutectic containing UCl{sub 3} and MgCl{sub 2}. Kinetic parameters were calculated for Mg{sup 2+} in LiCl-KCl eutectic. The exchange current density (i{sub o}) of Mg{sup 2+} deposition varied with mole fraction (x) according to i{sub o}(A cm{sup −2}) = 1.64x{sup 0.689}. The parameters from RCE measurements were also applied in an electrochemical co-deposition model entitled DREP to detect and predict the deposition rate of U and Mg. DREP succeeded in detecting the co-deposition of U and Mg, even when Mg constituted less than 0.5 wt% of the deposit.

Natural deep eutectic solvents (NADES) as green solvents for carbon dioxide capture

Science.gov (United States)

Mulia, Kamarza; Putri, Sylvania; Krisanti, Elsa; Nasruddin

2017-03-01

This study was conducted to determine the effectiveness of Natural Deep Eutectic Solvent (NADES), consisting of choline chloride and a hydrogen bonding donor (HBD) compound, in terms of carbon dioxide absorption. Solubility of carbon dioxide in NADES was found to be influenced HBD compound used and choline chloride to HBD ratio, carbon dioxide pressure, and contact time. HBD and choline/HBD ratios used were 1,2-propanediol (1:2), glycerol (1:2), and malic acid (1:1). The carbon dioxide absorption measurement was conducted using an apparatus that utilizes the volumetric method. Absorption curves were obtained up to pressures of 30 bar, showing a linear relationship between the amount absorbed and the final pressure of carbon dioxide. The choline and 1,2-propanediol eutectic mixture absorbs the highest amount of carbon dioxide, approaching 0.1 mole-fraction at 3.0 MPa and 50°C. We found that NADES ability to absorb carbon dioxide correlates with its polarity as tested using Nile Red as a solvatochromic probe.

Self-consistent theory of steady-state lamellar solidification in binary eutectic systems

International Nuclear Information System (INIS)

Nash, G.E.; Glicksman, M.E.

1976-01-01

The potential theoretic methods developed recently at NRL for solving the diffusion equation are applied to the free-boundary problem describing lamellar eutectic solidification. Using these techniques, the original boundary value problem is reduced to a set of coupled integro-differential equations for the shape of the solid/liquid interface and various quantities defined on the interface. The behavior of the solutions is discussed in a qualitative fashion, leading to some interesting inferences regarding the nature of the eutectic solidification process. Using the information obtained from the analysis referred to above, an approximate theory of the lamellar-rod transition is formulated. The predictions of the theory are shown to be in qualitative agreement with experimental observations of this transition. In addition, a simplified version of the general integro-differential equations is developed and is used to assess the effect of interface curvature on the interfacial solute concentrations, and to check the new theory for consistency with experiment

The effect of the electrode material on the electrodeposition of zinc from deep eutectic solvents

International Nuclear Information System (INIS)

Vieira, L.; Schennach, R.; Gollas, B.

2016-01-01

Highlights: • Mechanistic insight into zinc electrodeposition from deep eutectic solvents. • Overpotential for hydrogen evolution affects the electrodeposition of zinc. • Electrodeposited zinc forms surface alloys on Cu, Au, and Pt. • In situ PM-IRRAS of a ZnCl_2 containing deep eutectic solvent on glassy carbon. - Abstract: The voltammetric behaviour of the ZnCl_2 containing deep eutectic solvent choline chloride/ethylene glycol 1:2 was investigated on glassy carbon, stainless steel, Au, Pt, Cu, and Zn electrodes. While cyclic voltammetry on glassy carbon and stainless steel showed a cathodic peak for zinc electrodeposition only in the anodic reverse sweep, a cathodic peak was found also in the cathodic forward sweep on Au, Pt, Cu, and Zn. This behaviour is in agreement with the proposed mechanism of zinc deposition from an intermediate species Z, whose formation depends on the cathodic reduction potential of the solvent. The voltammetric reduction of the electrolyte involves hydrogen evolution and as a result the formation of Z and its reduction to zinc depend on the hydrogen overpotential for each electrode material. On Au, Pt, and Cu also the anodic stripping was different from that on glassy carbon and steel due to the formation of surface zinc alloys with the three former metals. The morphology of the zinc layers on Cu has been characterised by scanning electron microscopy and focussed ion beam. X-ray diffraction confirmed the presence of crystalline zinc and a Cu_4Zn phase. Spectroelectrochemistry by means of polarization modulation reflection-absorption spectroscopy (PM-IRRAS) on a glassy carbon electrode in the ZnCl_2 containing deep eutectic solvent showed characteristic potential dependent changes. The variation of band intensities at different applied potentials correlate with the voltammetry and suggest the formation of a compact blocking layer on the electrode surface, which inhibits the electrodeposition of zinc at sufficiently negative

Study on dewatering of chemical sludge by freeze-thaw process

International Nuclear Information System (INIS)

Xu Shikun; Liu Pin

1993-01-01

The treatment of radioactive sludge that is produced from treating radioactive waste water contains radioactively is different from that of non-radioactive sludge. The methods of immersing freeze and simulated two-step freeze have been studied for the elementary properties of simulated low-level radioactive sledge, the effect of freezing temperature, freeze time, and settling time on volume-reduction factor. Some parameters for design of freeze-thaw device are provided

Freeze-Casting of Porous Biomaterials: Structure, Properties and Opportunities

Directory of Open Access Journals (Sweden)

Sylvain Deville

2010-03-01

Full Text Available The freeze-casting of porous materials has received a great deal of attention during the past few years. This simple process, where a material suspension is simply frozen and then sublimated, provides materials with unique porous architectures, where the porosity is almost a direct replica of the frozen solvent crystals. This review focuses on the recent results on the process and the derived porous structures with regards to the biomaterials applications. Of particular interest is the architecture of the materials and the versatility of the process, which can be readily controlled and applied to biomaterials applications. A careful control of the starting formulation and processing conditions is required to control the integrity of the structure and resulting properties. Further in vitro and in vivo investigations are required to validate the potential of this new class of porous materials.

Hot big bang or slow freeze?

Science.gov (United States)

Wetterich, C.

2014-09-01

We confront the big bang for the beginning of the universe with an equivalent picture of a slow freeze - a very cold and slowly evolving universe. In the freeze picture the masses of elementary particles increase and the gravitational constant decreases with cosmic time, while the Newtonian attraction remains unchanged. The freeze and big bang pictures both describe the same observations or physical reality. We present a simple ;crossover model; without a big bang singularity. In the infinite past space-time is flat. Our model is compatible with present observations, describing the generation of primordial density fluctuations during inflation as well as the present transition to a dark energy-dominated universe.

Recent developments in smart freezing technology applied to fresh foods.

Science.gov (United States)

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

2017-09-02

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

Steady distribution structure of point defects near crystal-melt interface under pulling stop of CZ Si crystal

Science.gov (United States)

Abe, T.; Takahashi, T.; Shirai, K.

2017-02-01

In order to reveal a steady distribution structure of point defects of no growing Si on the solid-liquid interface, the crystals were grown at a high pulling rate, which Vs becomes predominant, and the pulling was suddenly stopped. After restoring the variations of the crystal by the pulling-stop, the crystals were then left in prolonged contact with the melt. Finally, the crystals were detached and rapidly cooled to freeze point defects and then a distribution of the point defects of the as-grown crystals was observed. As a result, a dislocation loop (DL) region, which is formed by the aggregation of interstitials (Is), was formed over the solid-liquid interface and was surrounded with a Vs-and-Is-free recombination region (Rc-region), although the entire crystals had been Vs rich in the beginning. It was also revealed that the crystal on the solid-liquid interface after the prolonged contact with the melt can partially have a Rc-region to be directly in contact with the melt, unlike a defect distribution of a solid-liquid interface that has been growing. This experimental result contradicts a hypothesis of Voronkov's diffusion model, which always assumes the equilibrium concentrations of Vs and Is as the boundary condition for distribution of point defects on the growth interface. The results were disscussed from a qualitative point of view of temperature distribution and thermal stress by the pulling-stop.

Freeze-all cycle for all normal responders?

Science.gov (United States)

Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo

2017-02-01

The purpose of this study is to evaluate the freeze-all strategy in subgroups of normal responders, to assess whether this strategy is beneficial regardless of ovarian response, and to evaluate the possibility of implementing an individualized embryo transfer (iET) based on ovarian response. This was an observational, cohort study performed in a private IVF center. A total of 938 IVF cycles were included in this study. The patients were submitted to controlled ovarian stimulation (COS) with a gonadotropin-releasing hormone (GnRH) antagonist protocol and a cleavage-stage day 3 embryo transfer. We performed a comparison of outcomes between the fresh embryo transfer (n = 523) and the freeze-all cycles (n = 415). The analysis was performed in two subgroups of patients based on the number of retrieved oocytes: Group 1 (4-9 oocytes) and Group 2 (10-15 oocytes). In Group 1 (4-9 retrieved oocytes), the implantation rates (IR) were 17.9 and 20.5% (P = 0.259) in the fresh and freeze-all group, respectively; the ongoing pregnancy rates (OPR) were 31 and 33% (P = 0.577) in the fresh and freeze-all group, respectively. In Group 2 (10-15 oocytes), the IR were 22.1 and 30.1% (P = 0.028) and the OPR were 34 and 47% (P = 0.021) in the fresh and freeze-all groups, respectively. Although the freeze-all policy may be related to better in vitro fertilization (IVF) outcomes in normal responders, these potential advantages decrease with worsening ovarian response. Patients with poorer ovarian response do not benefit from the freeze-all strategy.

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

Medical and social egg freezing

DEFF Research Database (Denmark)

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

2016-01-01

INTRODUCTION: Until recently, limited options for preserving fertility in order to delay childbearing were available. Although egg freezing and successful thawing is now possible, it remains unclear to what extent women are aware of the availability of this technique, their attitudes towards its...... use, or the circumstances under which this technique may be considered. MATERIAL AND METHODS: An online cross-sectional survey was designed to investigate knowledge and attitudes of women in Denmark and the UK on egg freezing and their potential intentions regarding the procedure. RESULTS: Data...... 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...

Response of seasonal soil freeze depth to climate change across China

Science.gov (United States)

Peng, Xiaoqing; Zhang, Tingjun; Frauenfeld, Oliver W.; Wang, Kang; Cao, Bin; Zhong, Xinyue; Su, Hang; Mu, Cuicui

2017-05-01

The response of seasonal soil freeze depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil freeze depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil freeze depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil freeze depth decreased significantly at a rate of -0.18 ± 0.03 cm yr-1, resulting in a net decrease of 8.05 ± 1.5 cm over 1967-2012 across China. On the regional scale, soil freeze depth decreases varied between 0.0 and 0.4 cm yr-1 in most parts of China during 1950-2009. By investigating potential climatic and environmental driving factors of soil freeze depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil freeze depth. Changes in snow depth are not correlated with soil freeze depth. Air and ground surface freezing indices are positively correlated with soil freeze depth. Comparing these potential driving factors of soil freeze depth, we find that freezing index and vegetation growth are more strongly correlated with soil freeze depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal freeze depth. These results are important for understanding the soil freeze-thaw dynamics and the impacts of soil freeze depth on ecosystem and hydrological process.

Effects of freezing conditions on quality changes in blueberries.

Science.gov (United States)

Cao, Xuehui; Zhang, Fangfang; Zhao, Dongyu; Zhu, Danshi; Li, Jianrong

2018-03-12

Freezing preservation is one of the most effective methods used to maintain the flavour and nutritional value of fruit. This research studied the effects of different freezing conditions, -20 °C, -40 °C, -80 °C, and immersion in liquid nitrogen, on quality changes of freeze-thawed blueberries. The water distribution estimates of blueberries were measured based on low-field nuclear magnetic resonance (LF-NMR) analysis. The pectin content, drip loss, and fruit texture were also detected to evaluate quality changes in samples. The freezing curves of blueberry showed super-cooling points at -20 °C and - 40 °C, whereas super-cooling points were not observed at -80 °C or in liquid nitrogen. After freeze-thaw treatment, the relaxation time of the cell wall water (T 21 ), cytoplasm water and extracellular space (T 22 ), and vacuole water (T 23 ) were significantly shortened compared to fresh samples, which suggested a lower liquidity. Although the freezing speed for samples immersed in liquid nitrogen was faster than other treatments, samples treated at -80 °C showed better quality regarding vacuole water holding, drip loss, and original pectin content retention. This study contributed to understanding how freezing temperature affects the qualities of blueberries. The super-fast freezing rate might injure fruit, and an appropriate freezing rate could better preserve blueberries. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

The effect of deep eutectic solvents on catalytic function and structure of bovine liver catalase.

Science.gov (United States)

Harifi-Mood, Ali Reza; Ghobadi, Roohollah; Divsalar, Adeleh

2017-02-01

Aqueous solutions of reline and glyceline, the most common deep eutectic solvents, were used as a medium for Catalase reaction. By some spectroscopic methods such as UV-vis, fluorescence and circular dichroism (CD) function and structure of Catalase were investigated in aqueous solutions of reline and glyceline. These studies showed that the binding affinity of the substrate to the enzyme increased in the presence of 100mM glyceline solution, which contrasts with reline solution that probably relates to instructive changes in secondary structure of protein. Meanwhile, enzyme remained nearly 70% and 80% active in this concentration of glyceline and reline solutions respectively. In the high concentration of DES solutions, enzyme became mainly inactive but surprisingly stayed in nearly 40% active in choline chloride solution, which is the common ion species in reline and glyceline solvents. It is proposed that the chaotropic nature of choline cation might stop the reducing trend of activity in concentrated choline chloride solutions but this instructive effect is lost in aqueous deep eutectic solvents. In this regard, the presence of various concentrations of deep eutectic solvents in the aqueous media of human cells would be an activity adjuster for this important enzyme in its different operation conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of freezing conditions on β-Tricalcium Phosphate /Camphene scaffold with micro sized particles fabricated by freeze casting.

Science.gov (United States)

Singh, Gurdev; Soundarapandian, S

2018-03-01

The long standing need of the implant manufacturing industries is to fabricate multi-matrix, customized porous scaffold as cost-effectively. In recent years, freeze casting has shown greater opportunity in the fabrication of porous scaffolds (tricalcium phosphate, hydroxyapatite, bioglass, alumina, etc.) such as at ease and good control over pore size, porosity, a range of materials and economic feasibility. In particular, tricalcium phosphate (TCP) has proved as it possesses good biocompatible (osteoinduction, osteoconduction, etc.) and biodegradability hence beta-tricalcium phosphate (β-TCP, particle size of 10µm) was used as base material and camphene was used as a freezing vehicle in this study. Both freezing conditions such as constant freezing temperature (CFT) and constant freezing rate (CFR) were used for six different conditional samples (CFT: 30, 35 and 40vol% solid loading; similarly CFR: 30, 35 and 40vol% solid loading) to study and understand the effect of various properties (pore size, porosity and compressive strength) of the freeze-cast porous scaffold. It was observed that the average size of the pore was varying linearly as from lower to higher when the solid loading was varying higher to lower. With the help of scanning electron micrographs (SEM), it was observed that the average size of pore during CFR (9.7/ 6.5/ 4.9µm) was comparatively higher than the process of CFT (6.0/ 4.8/ 2.6µm) with respect to the same solid loading (30/ 35/ 40vol%) conditions. From the Gas pycnometer analysis, it was found that the porosity in both freezing conditions (CFT, CFR) were almost near values such as 32.8% and 28.5%. Further to be observed that with the increase in solid loading, the total porosity value has decreased due to the reduction in the concentration of the freezing vehicle. Hence, the freezing vehicle was found as responsible for the formation of appropriate size and orientation of pores during freeze casting. The compressive strength (CS

Sr-Al-Si co-segregated regions in eutectic Si phase of Sr-modified Al-10Si alloy.

Science.gov (United States)

Timpel, M; Wanderka, N; Schlesiger, R; Yamamoto, T; Isheim, D; Schmitz, G; Matsumura, S; Banhart, J

2013-09-01

The addition of 200 ppm strontium to an Al-10 wt% Si casting alloy changes the morphology of the eutectic silicon phase from coarse plate-like to fine fibrous networks. In order to clarify this modification mechanism the location of Sr within the eutectic Si phase has been investigated by a combination of high-resolution methods. Whereas three-dimensional atom probe tomography allows us to visualise the distribution of Sr on the atomic scale and to analyse its local enrichment, transmission electron microscopy yields information about the crystallographic nature of segregated regions. Segregations with two kinds of morphologies were found at the intersections of Si twin lamellae: Sr-Al-Si co-segregations of rod-like morphology and Al-rich regions of spherical morphology. Both are responsible for the formation of a high density of multiple twins and promote the anisotropic growth of the eutectic Si phase in specific crystallographic directions during solidification. The experimental findings are related to the previously postulated mechanism of "impurity induced twinning". Copyright © 2012 Elsevier B.V. All rights reserved.

Highly Simple Deep Eutectic Solvent Extraction of Manganese in Vegetable Samples Prior to Its ICP-OES Analysis.

Science.gov (United States)

Bağda, Esra; Altundağ, Hüseyin; Soylak, Mustafa

2017-10-01

In the present work, simple and sensitive extraction methods for selective determination of manganese have been successfully developed. The methods were based on solubilization of manganese in deep eutectic solvent medium. Three deep eutectic solvents with choline chloride (vitamin B4) and tartaric/oxalic/citric acids have been prepared. Extraction parameters were optimized with using standard reference material (1573a tomato leaves). The quantitative recovery values were obtained with 1.25 g/L sample to deep eutectic solvent (DES) volume, at 95 °C for 2 h. The limit of detection was found as 0.50, 0.34, and 1.23 μg/L for DES/tartaric, DES/oxalic, and DES/citric acid, respectively. At optimum conditions, the analytical signal was linear for the range of 10-3000 μg/L for all studied DESs with the correlation coefficient >0.99. The extraction methods were applied to different real samples such as basil herb, spinach, dill, and cucumber barks. The known amount of manganese was spiked to samples, and good recovery results were obtained.

The choice of a suitable oligosaccharide to prevent aggregation of PEGylated nanoparticles during freeze thawing and freeze drying

NARCIS (Netherlands)

Hinrichs, Wouter; Manceñido, F A; Sanders, N N; Braeckmans, K; De Smedt, S C; Demeester, J; Frijlink, H W

2006-01-01

In a previous Study we have shown that the oligosaccharide inulin can prevent aggregation of poly(ethylene glycol) (PEG) coated plasmid DNA/cationic liposome complexes ('' PEGylated lipoplexes '') during freeze thawing and freeze drying [Hinrichs et al., 2005. J. Control. Release 103, 465]. By

Faktor Influencing the Vacuum Freezing Rate of Liquid Food

OpenAIRE

Tambunan, Armansyah H

2000-01-01

Many,freezing methods, mechanicul as well as cryogenic, have been in wide application in food industries. Each method has its own advantage, but in regard with the food quality, freezing rule can be accomplished by the method is one of the tnost important factors. Nowadays, many researchers are conducting experiment in order to enhance thefi.eezing rate. This paper deals with the advantage of vacuum freezing method in enhancing the freezing rate and its applicability for liquidfood.Experinren...

Increased spring freezing vulnerability for alpine shrubs under early snowmelt.

Science.gov (United States)

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

2014-05-01

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

Fundamental study on the salt distillation from the mixtures of rare earth precipitates and LiCl-KCl eutectic salt

International Nuclear Information System (INIS)

Yang, H. C.; Eun, H. C.; Cho, Y. Z.; Lee, H. S.; Kim, I. T.

2008-01-01

An electrorefining process of spent nuclear fuel generates waste salt containing some radioactive metal chlorides. The most effective method to reduce salt waste volume is to separate radioactive metals from non-radioactive salts. A promising approach is to change radioactive metal chlorides into salt-insoluble oxides by an oxygen sparging. Following this, salt distillation process is available to effectively separate the precipitated particulate metal oxides from salt. This study investigated the distillation rates of LiCl-KCl eutectic salt under different vacuums at elevated temperatures. The first part study investigated distillation rates of eutectic salt under different vacuums at high temperatures by using thermo-gravimetric furnace system. In the second part, we tested the removal of eutectic salt from the RE precipitates by using the laboratory vacuum distillation furnace system. Investigated variables were the temperature of mixture, the degree of vacuum and the time

Effects of Eutectic Si and Secondary Dendrite Arm Spacing on the Mechanical Properties of Al-Si-Cu Cast Alloys

International Nuclear Information System (INIS)

Lee, Kyungmin; Kim, Yumi; Kim, Youngman; Hong, Sungkil; Choi, Seweon; Kim, Youngchan; Kang, Changseok

2014-01-01

The present study aims at investigating the effects of eutectic Si and Secondary dendrite arm spacing (SDAS) on mechanical properties of Al-Si-Cu alloy. Heat treatment and controlling of solidification rate affect to microstructure of Al-Si-Cu alloy. Al-Si-Cu alloy was dissolved in an electric furnace. The alloy cast in STD61 mold which had been pre-heated to 95 ℃ and 200 ℃. Eutectic Si and SDAS were finer as cooling rate increased. Image analysis technique has been utilized to examine the microstructure. Microstructure observation results showed that T6 heat treatment has a strong influence eutectic Si particle morphology. The mechanical properties, such as tensile strength, yield strength, elongation, were improved by ASTM E8 standard. Tensile properties of the Al-Si-Cu alloys prepared by different cooling rates were the same as each other by T6 heat treatment.

Hot big bang or slow freeze?

Energy Technology Data Exchange (ETDEWEB)

Wetterich, C.

2014-09-07

We confront the big bang for the beginning of the universe with an equivalent picture of a slow freeze — a very cold and slowly evolving universe. In the freeze picture the masses of elementary particles increase and the gravitational constant decreases with cosmic time, while the Newtonian attraction remains unchanged. The freeze and big bang pictures both describe the same observations or physical reality. We present a simple “crossover model” without a big bang singularity. In the infinite past space–time is flat. Our model is compatible with present observations, describing the generation of primordial density fluctuations during inflation as well as the present transition to a dark energy-dominated universe.

Hot big bang or slow freeze?

International Nuclear Information System (INIS)

Wetterich, C.

2014-01-01

We confront the big bang for the beginning of the universe with an equivalent picture of a slow freeze — a very cold and slowly evolving universe. In the freeze picture the masses of elementary particles increase and the gravitational constant decreases with cosmic time, while the Newtonian attraction remains unchanged. The freeze and big bang pictures both describe the same observations or physical reality. We present a simple “crossover model” without a big bang singularity. In the infinite past space–time is flat. Our model is compatible with present observations, describing the generation of primordial density fluctuations during inflation as well as the present transition to a dark energy-dominated universe

Hot big bang or slow freeze?

Directory of Open Access Journals (Sweden)

C. Wetterich

2014-09-01

Full Text Available We confront the big bang for the beginning of the universe with an equivalent picture of a slow freeze — a very cold and slowly evolving universe. In the freeze picture the masses of elementary particles increase and the gravitational constant decreases with cosmic time, while the Newtonian attraction remains unchanged. The freeze and big bang pictures both describe the same observations or physical reality. We present a simple “crossover model” without a big bang singularity. In the infinite past space–time is flat. Our model is compatible with present observations, describing the generation of primordial density fluctuations during inflation as well as the present transition to a dark energy-dominated universe.

Directional solidification of Zn-Al-Cu eutectic alloy by the vertical Bridgman method

Directory of Open Access Journals (Sweden)

Büyük U.

2015-01-01

Full Text Available In the present work, the effect of growth rate and temperature gradient on microstructure and mechanical properties of Zn-7wt.%Al-4wt.%Cu eutectic alloy has been investigated. Alloys prepared under steady-state conditions by vacuumed hot filing furnace. Then, the alloys were directionally solidified upward with different growth rates (V=11.62-230.77 mm/s at a constant temperature gradient (G=7.17 K/mm and with different temperature gradients (G=7.17-11.04 K/mm at a constant growth rate (V=11.62 mm/s by a Bridgman furnace. The microstructures were observed to be lamellae of Zn, Al and broken lamellae CuZn4 phases from quenched samples. The values of eutectic spacing, microhardness and ultimate tensile strength of alloys were measured. The dependency of the microstructure and mechanical properties on growth rate and temperature gradient were investigated using regression analysis.

FREEZE DRYING PROCESS: A REVIEW

OpenAIRE

Soham Shukla

2011-01-01

Among the various methods of drying, this article has mentioned only one most important method, “Freeze drying”. This method is mainly used for the drying of thermo labile materials. This method works on the principle of sublimation. This method is divided into 3 steps for its better understanding; these are Freezing, Primary drying, and secondary drying. There are many advantages and disadvantages of this method, but still this is the most useful drying method nowadays.

Thermal characteristic investigation of eutectic composite fatty acid as heat storage material for solar heating and cooling application

Science.gov (United States)

Thaib, R.; Fauzi, H.; Ong, H. C.; Rizal, S.; Mahlia, T. M. I.; Riza, M.

2018-03-01

A composite phase change material (CPCM) of myristic acid/palmitic acid/sodium myristate (MA/PA/SM) and of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) were impregnated with purified damar gum as called Shorea Javanica (SJ) to improve the thermal conductivity of CPCM. The thermal properties, thermal conductivity, and thermal stability of both CPCM have investigated by using a Differential Scanning Calorimetry (DSC) thermal analysis, hot disc thermal conductivity analyzer, and Simultaneous Thermal Analyzer (STA), simultaneously. However, a chemical compatibility between both fatty acid eutectic mixtures and SJ in composite mixtures measured by Fourier Transform Infra-Red (FT-IR) spectrophotometer. The results were obtained that the thermal conductivity of MA/PA/SM/SJ and MA/PA/SL/SJ eutectic composite phase change material (CPCM) were improved by addition 3 wt.% and 2 wt.% of Shorea javanica (SJ), respectively, without occur a significant change on thermal properties of CPCM. Moreover, the absorbance spectrum of FT-IR shows the good compatibility of SJ with both MA/PA/SM and MA/PA/SL eutectic mixtures, the composite PCM also present good thermal performance and good thermal stability. Therefore, it can be noted that the purified Shorea Javanica proposed, the as high conductive material in this study was able to improve the thermal conductivity of eutectic PCM without any significant reduction on its thermo-physical and chemical properties and can be recommended as novelty composite phase change material for thermal energy storage application.

Successful long-term preservation of rat sperm by freeze-drying.

Directory of Open Access Journals (Sweden)

Takehito Kaneko

Full Text Available BACKGROUND: Freeze-drying sperm has been developed as a new preservation method where liquid nitrogen is no longer necessary. An advantage of freeze-drying sperm is that it can be stored at 4 °C and transported at room temperature. Although the successful freeze-drying of sperm has been reported in a number of animals, the possibility of long-term preservation using this method has not yet been studied. METHODOLOGY/PRINCIPAL FINDINGS: Offspring were obtained from oocytes fertilized with rat epididymal sperm freeze-dried using a solution containing 10 mM Tris and 1 mM EDTA adjusted to pH 8.0. Tolerance of testicular sperm to freeze-drying was increased by pre-treatment with diamide. Offspring with normal fertility were obtained from oocytes fertilized with freeze-dried epididymal sperm stored at 4 °C for 5 years. CONCLUSIONS AND SIGNIFICANCE: Sperm with -SS- cross-linking in the thiol-disulfide of their protamine were highly tolerant to freeze-drying, and the fertility of freeze-dried sperm was maintained for 5 years without deterioration. This is the first report to demonstrate the successful freeze-drying of sperm using a new and simple method for long-term preservation.

Optimization of protectant, salinity and freezing condition for freeze-drying preservation of Edwardsiella tarda

Science.gov (United States)

Yu, Yongxiang; Zhang, Zheng; Wang, Yingeng; Liao, Meijie; Li, Bin; Xue, Liangyi

2017-10-01

Novel preservation condition without ultra-low temperature is needed for the study of pathogen in marine fishes. Freeze-drying is such a method usually used for preservation of terrigenous bacteria. However, studies using freeze-drying method to preserving marine microorganisms remain very limited. In this study, we optimized the composition of protectants during the freeze-drying of Edwardsiella tarda, a fish pathogen that causes systemic infection in marine fishes. We found that the optimal composition of protectant mixture contained trehalose (8.0%), skim milk (12.0%), sodium citrate (2.0%), serum (12.0%) and PVP (2.0%). Orthogonal and interaction analyses demonstrated the interaction between serum and skim milk or sodium citrate. The highest survival rate of E. tarda was observed when the concentration of NaCl was 10.0, 30.0 and between 5.0 and 10.0 g L-1 for preparing TSB medium, E. tarda suspension and protectant mixture, respectively. When E. tarda was frozen at -80°C or -40°C for 6 h, its survival rate was higher than that under other tested conditions. Under the optimized conditions, when the protectant mixture was used during freeze-drying process, the survival rate (79.63%-82.30%) of E. tarda was significantly higher than that obtained using single protectant. Scanning electron microscopy (SEM) image indicated that E. tarda was embedded in thick matrix with detectable aggregation. In sum, the protectant mixture may be used as a novel cryoprotective additive for E. tarda.

Thermophysical properties and solubility of different sugar-derived molecules in deep eutectic solvents

NARCIS (Netherlands)

Dietz, C.H.J.T.; Kroon, M.C.; van Sint Annaland, M.; Gallucci, F.

2017-01-01

Deep eutectic solvents (DESs) are designer solvents analogous to ionic liquids but with lower preparation cost. Most known DESs are water-miscible, but recently water-immiscible DESs have also been presented, which are a combination of hydrogen bond donors and acceptors with long hydrophobic alkyl

Deep Metastable Eutectic Nanometer-Scale Particles in the MgO-Al2O3-SiO2 System

Science.gov (United States)

Reitmeijer, Frans J. M.; Nash, J. A., III

2011-01-01

Laboratory vapor phase condensation experiments systematically yield amorphous, homogeneous, nanoparticles with unique deep metastable eutectic compositions. They formed during the nucleation stage in rapidly cooling vapor systems. These nanoparticles evidence the complexity of the nucleation stage. Similar complex behavior may occur during the nucleation stage in quenched-melt laboratory experiments. Because of the bulk size of the quenched system many of such deep metastable eutectic nanodomains will anneal and adjust to local equilibrium but some will persist metastably depending on the time-temperature regime and melt/glass transformation.

Optimization Of Freeze-Dried Starter For Yogurt By Full Factorial Experimental Design

Directory of Open Access Journals (Sweden)

Chen He

2015-12-01

Full Text Available With the rapidly development of fermented milk product, it is significant for enhancing the performance of starter culture. This paper not only investigated the influence of anti-freeze factors and freeze-drying protective agents on viable count, freeze-drying survival rate and yield of Lactobacillus bulgaricus (LB and Streptococcus thermophilus (ST, but also optimized the bacteria proportion of freeze-dried starter culture for yogurt by full factorial experimental design. The results showed as following: the freeze-drying protective agents or anti-freeze factors could enhanced survival rate of LB and ST; the freeze-dried LB and ST powders containing both of anti-freeze factors and freeze-drying protective agents had higher viable count and freeze-drying survival rate that were 84.7% and 79.7% respectively; In terms of fermentation performance, the best group of freeze-dried starter for yogurt was the compound of LB3 and ST2.

Comparison of Freezing and Hydrate Formation Methods in Removing Chloride and Bromide Ions from Brine

Directory of Open Access Journals (Sweden)

Marzieh Fattahi

2018-01-01

Full Text Available The growing population and enhanced industrial activities coupled with limitations on freshwater availability have led to efforts to desalinate salt water from the seas. Membrane and thermal technologies are the two commonly used for this purpose. In this study, the direct freezing and hydrate formation techniques were used for salt water desalination. Materials and Methods: Distilled water, sodium chloride, and sodium bromide were used as raw materials in the experiments. The experimental setup included a stationary reactor with two coaxial cylinders, in which ice crystals were deposited outside the cool inner cylinder to increase the salt concentration in the residual brine. An electrical conductivity instrument was used to measure sal removal. Results: Salt removal was shown to decrease with increasing salt concentration in the direct freeze method. A different trend was, however, observed in the hydrate formation method; salt removal was negligible at low concentrations in this method but increased at high concentrations before a constant value was reached. Overall, the hydrate formation recorded a higher salt removal efficiency than the other method. To investigate the effect of anion size on salt removal efficiency, experiments were carried out using NaCl and NaBr, which have the same cation but different anion sizes. Result showed that removal efficiency increased with increasing anion size. Conclusion: It was found that increasing ion radius leads to the lower likelihood of ion presence in the crystal lattice, thereby reducing salt removal efficiency. On the other hand, low concentrations of salt serve as site for the generation of cores, which naturally serve as removal accelerators.

The influence of high gravity in PbSn eutectic alloy

Energy Technology Data Exchange (ETDEWEB)

Freitas, F.E.; Toledo, R.C.; Poli, A.K.S.; An, C.Y.; Bandeira, I.N., E-mail: filipe.estevao@gmail.com, E-mail: chen@las.inpe.br [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil)

2014-07-01

The study of materials processed in centrifuges improves the understanding of the acceleration influence in the convection behavior in materials processing. This work aims to study the influence of high gravity in PbSn eutectic alloy solidification using a small centrifuge designed and built in the Associate Laboratory of Sensors and Materials of the Brazilian Space Research Institute (LAS/INPE). The samples were analyzed by densitometry and scanning electron microscopy (SEM). (author)

A rapidly negotiable first-stage nuclear freeze

International Nuclear Information System (INIS)

Anon.

1988-01-01

This paper reports on the objective of a nuclear freeze which is to slow down or stop the so-far inexorable development and deployment of more and more (read destructive and deadly) nuclear warheads. The essential notion is not new. The proposed treaty for a comprehensive ban on nuclear tests that was very nearly negotiated in 1959 was perhaps the first serious effort to obtain a nuclear freeze, albeit a partial one. Growing concern about the nuclear arms race has led to greatly increased interest in much broader and more effective freezes. A comprehensive nuclear freeze, one that would stop all stages in the manufacture, testing, and deployment of nuclear warheads, would clearly be very desirable and have a great impact. It would not, however, deal with the other worrisome aspects of nuclear weapons, which is the very large number of such weapons that already exist

Mechanisms of deterioration of nutrients. [improved quality of freeze-dried foods

Science.gov (United States)

Karel, M.; Flink, J. M.

1978-01-01

Methods for improving the quality of freeze-dried foods were investigated. Areas discussed include: (1) microstructure of freeze-dried systems, (2) structural changes in freeze-dried systems, (3) artificial food matrices, and (4) osmotic preconcentration to yield improved freeze-dried products.

Conformational and bioactivity analysis of insulin: freeze-drying TBA/water co-solvent system in the presence of surfactant and sugar.

Science.gov (United States)

Zhang, Yong; Deng, Yingjie; Wang, Xueli; Xu, Jinghua; Li, Zhengqiang

2009-04-17

Despite the extensive research into the freeze-drying of aqueous solutions of proteins, it remains unknown whether proteins can survive the lyophilization process in a water-organic co-solvent system and how the process and additives affect the structural stability and activity of the proteins. In the present study, a conformational analysis of insulin in the absence/presence of bile salt and trehalose was carried out, before and after freeze-drying of a tert-butyl alcohol (TBA)/water co-solvent system at volume ratios of TBA to water ranging from 50/50 to 0/100. The study involved the use of ultraviolet derivative and fluorescence spectroscopy, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy. Also the bioactivity of insulin was evaluated in vivo using the streptozotocin (STZ)-induced diabetic mice as an animal model. Initial investigations indicate that the extent of the structural change of insulin depends significantly both on the TBA content and on the concentration of additives, such as sodium deoxycholate, prior to lyophilization. This could be accounted for by the phase behavior properties of the TBA/water co-solvent system, surface denaturation together with the selective and/or forced dispersion of insulin during phase separation. Lyophilized insulin in the presence of bile salt and trehalose retained more of its bioactivity and native-like structure in the solid state compared with that in the absence of additives at various TBA/water ratios, although in all cases there was a major and reversible rearrangement of secondary structure after rehydration, except for insulin at 50% TBA (v/v). Furthermore, both lyophilization in non-eutectic systems and less structural changes in the formulation process lead to more bioactivity.

Bright metal coatings from sustainable electrolytes: the effect of molecular additives on electrodeposition of nickel from a deep eutectic solvent.

Science.gov (United States)

Abbott, Andrew P; Ballantyne, Andrew; Harris, Robert C; Juma, Jamil A; Ryder, Karl S

2017-01-25

Organic and inorganic additives are often added to nickel electroplating solutions to improve surface finish, reduce roughness and promote uniform surface morphology of the coatings. Such additives are usually small molecules and often referred to as brighteners or levellers. However, there have been limited investigations into the effect of such additives on electrodeposition from ionic liquids (ILs) and deep eutectic solvents (DESs). Here we study the effect of four additives on electrolytic nickel plating from an ethyleneglycol based DES; these are nicotinic acid (NA), methylnicotinate (MN), 5,5-dimethylhydantoin (DMH) and boric acid (BA). The additives show limited influence on the bulk Ni(ii) speciation but have significant influence on the electrochemical behaviour of Ni deposition. Small concentrations (ca. 15 mM) of NA and MN show inhibition of Ni(ii) reduction whereas high concentrations of DMH and BA are required for a modest difference in behaviour from the additive free system. NA and MN also show that they significantly alter the nucleation and growth mechanism when compared to the additive free system and those with DMH and BA. Each of the additive systems had the effect of producing brighter and flatter bulk electrodeposits with increased coating hardness but XRD shows that NA and MN direct crystal growth to the [111] orientation whereas DMH and BA direct crystal growth to the [220] orientation.

Vaporization of liquid Pb-Li eutectic alloy from 1000K to 1200K - A high temperature mass spectrometric study

Science.gov (United States)

Jain, U.; Mukherjee, A.; Dey, G. K.

2017-09-01

Liquid lead-lithium eutectic will be used as a coolant in fusion reactor blanket loop. Vapor pressure of the eutectic is an important parameter to accurately predict its in-loop behavior. Past measurements of vapor pressure of the eutectic relied on indirect methods. In this paper, we report for the first time the in-situ vaporization behavior of the liquid alloy between 1042 and 1176 K by Knudsen effusion mass spectrometry (KEMS). It was seen that the vaporization occurred by independent evaporation of lead and lithium. No complex intermetallic vapor was seen in the mass spectra. The partial pressures and enthalpy of vaporization of Pb and Li were evaluated directly from the measured ion intensities formed from the equilibrium vapor over the alloy. The activity of Li over a temperature range of 1042-1176 K was found to be 4.8 × 10-5 to that of pure Li, indicating its very low activity in the alloy.

Reduction behavior of UO22+ in molten LiCl–RbCl and LiCl–KCl eutectics by using tungsten

International Nuclear Information System (INIS)

Nagai, Takayuki; Uehara, Akihiro; Fujii, Toshiyuki; Yamana, Hajimu

2013-01-01

The reduction of uranium from UO 2 2+ to UO 2 + or U 4+ in molten LiCl–RbCl and LiCl–KCl eutectics was examined by using tungsten and chlorine gas. Spectrophotometric technique was adopted to determine the concentration of uranium species. When tungsten was immersed into the LiCl–RbCl eutectic melt at 400 °C without supplying chlorine gas, 36% of the total weight of the hexavalent of UO 2 2+ was reduced to the pentavalent of UO 2 + . Under purging chlorine gas into the melt, 96% of UO 2 2+ was reduced to the tetravalent of U 4+ . Tungsten oxy-chloride of WOCl 4 was produced via the reductions of UO 2 2+ , which was volatized from the melt and adsorbed on the upper part of experimental cell. On the other hand, 84% of UO 2 2+ in the LiCl–KCl eutectic melt at 500 °C was reduced to U 4+ by using tungsten and chlorine gas

Reduction behavior of UO22+ in molten LiCl-RbCl and LiCl-KCl eutectics by using tungsten

Science.gov (United States)

Nagai, Takayuki; Uehara, Akihiro; Fujii, Toshiyuki; Yamana, Hajimu

2013-08-01

The reduction of uranium from UO22+ to UO2+ or U4+ in molten LiCl-RbCl and LiCl-KCl eutectics was examined by using tungsten and chlorine gas. Spectrophotometric technique was adopted to determine the concentration of uranium species. When tungsten was immersed into the LiCl-RbCl eutectic melt at 400 °C without supplying chlorine gas, 36% of the total weight of the hexavalent of UO22+ was reduced to the pentavalent of UO2+. Under purging chlorine gas into the melt, 96% of UO22+ was reduced to the tetravalent of U4+. Tungsten oxy-chloride of WOCl4 was produced via the reductions of UO22+, which was volatized from the melt and adsorbed on the upper part of experimental cell. On the other hand, 84% of UO22+ in the LiCl-KCl eutectic melt at 500 °C was reduced to U4+ by using tungsten and chlorine gas.

Cost-Effectiveness of the Freeze-All Policy.

Science.gov (United States)

Roque, Matheus; Valle, Marcello; Guimarães, Fernando; Sampaio, Marcos; Geber, Selmo

2015-08-01

To evaluate the cost-effectiveness of freeze-all cycles when compared to fresh embryo transfer. This was an observational study with a cost-effectiveness analysis. The analysis consisted of 530 intracytoplasmic sperm injection (ICSI) cycles in a private center in Brazil between January 2012 and December 2013. A total of 530 intracytoplasmic sperm injection (ICSI) cycles - 351 fresh embryo transfers and 179 freeze-all cycles - with a gonadotropin-releasing hormone (GnRH) antagonist protocol and day 3 embryo transfers. The pregnancy rate was 31.1% in the fresh group and 39.7% in the freeze-all group. We performed two scenario analyses for costs. In scenario 1, we included those costs associated with the ICSI cycle (monitoring during controlled ovarian stimulation [COS], oocyte retrieval, embryo transfer, IVF laboratory, and medical costs), embryo cryopreservation of supernumerary embryos, hormone measurements during COS and endometrial priming, medication use (during COS, endometrial priming, and luteal phase support), ultrasound scan for frozen- thawed embryo transfer (FET), obstetric ultrasounds, and miscarriage. The total cost (in USD) per pregnancy was statistically lower in the freeze-all cycles (19,156.73 ± 1,732.99) when compared to the fresh cycles (23,059.72 ± 2,347.02). Even in Scenario 2, when charging all of the patients in the freeze-all group for cryopreservation (regardless of supernumerary embryos) and for FET, the fresh cycles had a statistically significant increase in treatment costs per ongoing pregnancy. The results presented in this study suggest that the freeze-all policy is a cost-effective strategy when compared to fresh embryo transfer.

Spray-Freeze Drying: a Suitable Method for Aerosol Delivery of Antibodies in the Presence of Trehalose and Cyclodextrins.

Science.gov (United States)

Pouya, Maryam Amini; Daneshmand, Behnaz; Aghababaie, Shabnam; Faghihi, Homa; Vatanara, Alireza

2018-05-08

We aimed to prepare spray-freeze-dried powder of IgG considering physicochemical stability and aerodynamic aspects. Spray-freeze drying (SFD) exposes proteins to various stresses which should be compensated by suitable stabilizers. The competence of cyclodextrins (CDs), namely beta-cyclodextrin (βCD) and hydroxypropyl βCD (HPβCD), at very low concentrations, was investigated in the presence of separate mannitol- and trehalose-based formulations. Spray-freeze-dried preparations were quantified in terms of monomer recovery and conformation by size exclusion chromatography (SEC-HPLC) and Fourier transform infrared (FTIR) spectroscopy, respectively. Differential scanning calorimetry (DSC) and X-ray diffractometry (XRD) were employed to identify the thermal characteristics of powders. Particle morphology was visualized by scanning electron microscopy (SEM). Aerodynamic behavior of powders was checked through an Anderson cascade impactor (ACI). Although all formulations protected antibody from aggregation during the SFD process (aggregation < 1%), mannitol-containing ones failed upon the storage (19.54% in the worst case). Trehalose-HPβCD incomparably preserved the formulation with fine particle fraction (FPF) of 51.29%. Crystallization of mannitol resulted in IgG destabilization upon storage. Although employed concentration of CDs is too low (less than 50:1 molar ratio to protein), they successfully served as stabilizing agents in SFD with perfect improvement in aerosol functionality. Graphical Abstract ᅟ.

Research and Development of Crystal Purification for Product of Uranium Crystallization Process

Energy Technology Data Exchange (ETDEWEB)

Yano, K. [Japan Atomic Energy Agency - JAEA (Japan)

2009-06-15

Uranium crystallization has been developed as a part of advanced aqueous reprocessing for FBR spent fuel. Although the purity of uranyl nitrate hexahydrate (UNH) crystal from the crystallization process is supposed to meet a specification of FBR blanket fuel, an improvement of its purity is able to reduce the cost of fuel fabrication and storage (in case interim storage of recovered uranium is required). In this work, UNH crystal purification was developed as additional process after crystallization. Contamination of the crystal is caused by mother solution and solid state impurities. They are inseparable by washing and filtration. Mother solution on the surface of UNH crystals is removable by washing, but it is difficult to remove that in an obstructed part of crystalline aggregate by washing. Major elements of solid state impurities are cesium and barium. Cesium precipitates with tetravalent plutonium as a double nitrate, Cs{sub 2}Pu(NO{sub 3}){sub 6}. Barium crystallizes as Ba(NO{sub 3}){sub 2} because of its low solubility in nitric acid solution. It is difficult to separate their particle from UNH crystal by solid-liquid separation such as simple filtration. As a kind of crystal purification, there are some methods using sweating. Sweating is a phenomenon that a crystal melts partly below its melting point and it is caused by depression of freezing point due to impurity. It is considerably applicable for removal of mother solution. Concerning the solid state impurities, which has higher melting point than that of UNH crystal, it is supposed that they are separable by melting UNH crystal and filtration. The behaviors of impurities and applicability of sweating and melting-filtration operations to the purification for UNH crystal were investigated experimentally on a beaker and an engineering scale. With regard to behaviors of impurities, the conditions of cesium and barium precipitation were surveyed and it was clarified that there were most impurities on the

Green Processing of Lignocellulosic Biomass and Its Derivatives in Deep Eutectic Solvents.

Science.gov (United States)

Tang, Xing; Zuo, Miao; Li, Zheng; Liu, Huai; Xiong, Caixia; Zeng, Xianhai; Sun, Yong; Hu, Lei; Liu, Shijie; Lei, Tingzhou; Lin, Lu

2017-07-10

The scientific community has been seeking cost-competitive and green solvents with good dissolving capacity for the valorization of lignocellulosic biomass. At this point, deep eutectic solvents (DESs) are currently emerging as a new class of promising solvents that are generally liquid eutectic mixtures formed by self-association (or hydrogen-bonding interaction) of two or three components. DESs are attractive solvents for the fractionation (or pretreatment) of lignocellulose and the valorization of lignin, owing to the high solubility of lignin in DESs. DESs are also employed as effective media for the modification of cellulose to afford functionalized cellulosic materials, such as cellulose nanocrystals. More interestingly, biomassderived carbohydrates, such as fructose, can be used as one of the constituents of DESs and then dehydrated to 5-hydroxymethylfurfural in high yield. In this review, a comprehensive summary of recent contribution of DESs to the processing of lignocellulosic biomass and its derivatives is provided. Moreover, further discussion about the challenges of the application of DESs in biomass processing is presented. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Scintillation properties of LiF–SrF2 and LiF–CaF2 eutectic

International Nuclear Information System (INIS)

Yanagida, Takayuki; Kawaguchi, Noriaki; Fujimoto, Yutaka; Fukuda, Kentaro; Watanabe, Kenichi; Yamazaki, Atsushi; Uritani, Akira

2013-01-01

Dopant free eutectic scintillators 6 LiF–SrF 2 and 6 LiF–CaF 2 were developed by the vertical Bridgeman method for the purpose of thermal neutron detection. The molar ratio of LiF and Ca/SrF 2 was 4:1 on its eutectic composition. The α-ray induced radioluminescence spectra of the scintillators showed intense emission peak at 300 nm due to the emission from the self-trapped exciton in Ca/SrF 2 layers. When the samples were irradiated with 252 Cf neutrons, 6 LiF–SrF 2 and 6 LiF–CaF 2 exhibited the light yields of 4700 and 9400 ph/n, respectively. Scintillation decay times of 6 LiF–SrF 2 and 6 LiF–CaF 2 were accepted for scintillation detectors, 90 and 250 ns, respectively. -- Highlights: • Nondoped LiF–CaF 2 and LiF–SrF 2 eutectic scinitillators are reported for the first time. • Two sample showed self-trapped exciton emission. • LiF–SrF 2 sample exhibited the light yield of 9400 ph/n and this value was comparable to conventional materials doped with rare earth ions. • Scintillation decay times of LiF–CaF 2 and LiF–SrF 2 were 250 and 90 ns, respectively

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.

Recovery of Residual LiCl-KCl Eutectic Salts in Radioactive Rare Earth Precipitates

International Nuclear Information System (INIS)

Eun, Hee Chul; Yang, Hee Chul; Kim, In Tae; Lee, Han Soo; Cho, Yung Zun

2010-01-01

For the pyrochemical process of spent nuclear fuels, recovery of LiCl-KCl eutectic salts is needed to reduce radioactive waste volume and to recycle resource materials. This paper is about recovery of residual LiCl-KCl eutectic salts in radioactive rare earth precipitates (rare earth oxychlorides or oxides) by using a vacuum distillation process. In the vacuum distillation test apparatus, the salts in the rare earth precipitates were vaporized and were separated effectively. The separated salts were deposited in three positions of the vacuum distillation test apparatus or were collected in the filter and it is difficult to recover them. To resolve the problem, a vacuum distillation and condensation system, which is subjected to the force of a temperature gradient at a reduced pressure, was developed. In a preliminary test of the vacuum distillation/condensation recovery system, it was confirmed that it was possible to condense the vaporized salts only in the salt collector and to recover the condensed salts from the salt collector easily

Applications of Simulator Freeze to Carrier Glideslope Tracking Instruction.

Science.gov (United States)

1982-07-01

Showing Datum Bars and Meatball . .. .. .. ... .. ... .... 19 4 Freezes Per Trial Averaged Across Freeze Conditions and Across 4-Trial Blocks of Training...algorithm linearly increased the criterion in meatball units from 1.0 at 6000 feet from the ramp to 1.5 at the ramp. "Freezes" did not occur beyond 6000

A comparative study on the compatibility of liquid lead–gold eutectic and liquid lead–bismuth eutectic with T91 and SS 316LN steels

International Nuclear Information System (INIS)

Dai, Y.; Gao, W.; Zhang, T.; Platacis, E.; Heinitz, S.; Thomsen, K.

2012-01-01

Liquid lead–gold eutectic (LGE) is considered as a potential target material for high power spallation sources. In the present work, the corrosion effects of LGE on T91 and SS 316LN steels have been investigated in comparison with that of liquid lead–bismuth eutectic (LBE) under the same testing conditions. Two tests were conducted at 400 °C for 1800 h and at 450 °C for 1300 h, in which specimens of the two steels were exposed to 1 m/s flowing LGE and LBE. Surface inspections showed that the specimens underwent a mixed corrosion mode of dissolution and oxidation. The results obtained from the SS 316LN specimens are very interesting. Firstly, EDX (electron energy dispersion X-ray spectrometry) analyses revealed that Ni, Cr and Mn have a higher dissolution rate in LGE than in LBE. Secondly, it was observed that LBE attacked strongly on grain-boundaries (GBs) and twin-boundaries (TBs), while LGE did not preferentially attack GBs and TBs. Further, the diffusion or penetration paths of LBE look straight, while those of LGE look like a complex network. In the attacked regions the chemical composition of the steel did not change much in the LBE case, but changed greatly in the LGE case. The T91 specimens exhibited considerably weaker corrosion effects under the present testing conditions.

Freeze block testing of buried waste lines

International Nuclear Information System (INIS)

Robbins, E.D.; Willi, J.C.

1976-01-01

An investigation was conducted to demonstrate application of freeze blocking in waste transfer lines such that a hydrostatic pressure test can be applied. A shop test was conducted on a 20-foot length, 3-inch schedule 40, carbon steel pipe using a coolant of dry ice and Freon. The positive results from these tests prompted a similar employment of the freeze block method in hydrostatic pressure testing the feed inlet leading to 241-S-101 Waste Tank. This pipeline is a 3-inch schedule 10, stainless steel pipe approximately 800 feet long. The freeze block was formed near the lower end of the pipe as it entered the 101-S Waste Tank and a pressure hold test was applied to this pipeline. This test proved the integrity of the pipeline in question, and demonstrated the validity of freeze blocking an open-ended pipeline which could not be hydrotested in other conventional ways. The field demonstration facility, costing $30,200 was completed late in 1975

Predictive modeling of freezing and thawing of frost-susceptible soils.

Science.gov (United States)

2015-09-01

Frost depth is an essential factor in design of various transportation infrastructures. In frost : susceptible soils, as soils freezes, water migrates through the soil voids below the freezing line : towards the freezing front and causes excessive he...

Multiple Glass Transitions and Freezing Events of Aqueous Citric Acid

Science.gov (United States)

2014-01-01

Calorimetric and optical cryo-microscope measurements of 10–64 wt % citric acid (CA) solutions subjected to moderate (3 K/min) and slow (0.5 and 0.1 K/min) cooling/warming rates and also to quenching/moderate warming between 320 and 133 K are presented. Depending on solution concentration and cooling rate, the obtained thermograms show one freezing event and from one to three liquid–glass transitions upon cooling and from one to six liquid–glass and reverse glass–liquid transitions, one or two freezing events, and one melting event upon warming of frozen/glassy CA/H2O. The multiple freezing events and glass transitions pertain to the mother CA/H2O solution itself and two freeze-concentrated solution regions, FCS1 and FCS2, of different concentrations. The FCS1 and FCS2 (or FCS22) are formed during the freezing of CA/H2O upon cooling and/or during the freezing upon warming of partly glassy or entirely glassy mother CA/H2O. The formation of two FCS1 and FCS22 regions during the freezing upon warming to our best knowledge has never been reported before. Using an optical cryo-microscope, we are able to observe the formation of a continuous ice framework (IF) and its morphology and reciprocal distribution of IF/(FCS1 + FCS2). Our results provide a new look at the freezing and glass transition behavior of aqueous solutions and can be used for the optimization of lyophilization and freezing of foods and biopharmaceutical formulations, among many other applications where freezing plays a crucial role. PMID:25482069

Filtration of aluminum alloys and its influence on mechanical properties and shape of eutectical silicium

Directory of Open Access Journals (Sweden)

M. Brůna

2008-07-01

Full Text Available Filtration during casting of high quality aluminum alloys belongs to main refining methods. Even when there are many years of experiences and experimental works on this subject, there are still some specific anomalies. While using ceramic filtration media during casting of aluminum alloys, almost in all experiments occurred increase of strength limit and atypical increase of extension. This anomaly was not explained with classical metallurgical methods, black-white contrast after surface etching neither with color surface etching. For that reason was used deep etching on REM. By using pressed ceramic filters, by studying morphology eutectical silicon was observed modification morphology of eutectical silicon, this explains increase extension after filtration. Pressed ceramic filters were used on experimental works. Casting was executed on hardenable alloy AlSi10MgMn.

Application of freeze-drying technology in manufacturing orally disintegrating films.

Science.gov (United States)

Liew, Kai Bin; Odeniyi, Michael Ayodele; Peh, Kok-Khiang

2016-01-01

Freeze drying technology has not been maximized and reported in manufacturing orally disintegrating films. The aim of this study was to explore the freeze drying technology in the formulation of sildenafil orally disintegrating films and compare the physical properties with heat-dried orally disintegrating film. Central composite design was used to investigate the effects of three factors, namely concentration of carbopol, wheat starch and polyethylene glycol 400 on the tensile strength and disintegration time of the film. Heat-dried films had higher tensile strength than films prepared using freeze-dried method. For folding endurance, freeze-dried films showed improved endurance than heat-dried films. Moreover, films prepared using freeze-dried methods were thicker and had faster disintegration time. Formulations with higher amount of carbopol and starch showed higher tensile strength and thickness whereas formulations with higher PEG 400 content showed better flexibility. Scanning electron microscopy showed that the freeze-dried films had more porous structure compared to the heat-dried film as a result of the release of water molecule from the frozen structure when it was subjected to freeze drying process. The sildenafil film was palatable. The dissolution profiles of freeze-dried and heat-dried films were similar to Viagra® with f2 of 51.04 and 65.98, respectively.

A liquid-based eutectic system: LiBH4·NH 3-nNH3BH3 with high dehydrogenation capacity at moderate temperature

KAUST Repository

Tan, Yingbin; Guo, Yanhui; Li, Shaofeng; Sun, Weiwei; Zhu, Yihan; Li, Qi; Yu, Xuebin

2011-01-01

A novel eutectic hydrogen storage system, LiBH4·NH 3-nNH3BH3, which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH 4·NH3 and NH3BH3 (AB). In the temperature range of 90-110 °C, the eutectic system

CATALYTIC GASIFICATION OF COAL USING EUTECTIC SALT MIXTURES

Energy Technology Data Exchange (ETDEWEB)

Dr. Yaw D. Yeboah; Dr. Yong Xu; Dr. Atul Sheth; Dr. Pradeep Agrawal

2001-12-01

The Gas Research Institute (GRI) estimates that by the year 2010, 40% or more of U.S. gas supply will be provided by supplements including substitute natural gas (SNG) from coal. These supplements must be cost competitive with other energy sources. The first generation technologies for coal gasification e.g. the Lurgi Pressure Gasification Process and the relatively newer technologies e.g. the KBW (Westinghouse) Ash Agglomerating Fluidized-Bed, U-Gas Ash Agglomerating Fluidized-Bed, British Gas Corporation/Lurgi Slagging Gasifier, Texaco Moving-Bed Gasifier, and Dow and Shell Gasification Processes, have several disadvantages. These disadvantages include high severities of gasification conditions, low methane production, high oxygen consumption, inability to handle caking coals, and unattractive economics. Another problem encountered in catalytic coal gasification is deactivation of hydroxide forms of alkali and alkaline earth metal catalysts by oxides of carbon (CO{sub x}). To seek solutions to these problems, a team consisting of Clark Atlanta University (CAU, a Historically Black College and University, HBCU), the University of Tennessee Space Institute (UTSI) and Georgia Institute of Technology (Georgia Tech) proposed to identify suitable low melting eutectic salt mixtures for improved coal gasification. The research objectives of this project were to: Identify appropriate eutectic salt mixture catalysts for coal gasification; Assess agglomeration tendency of catalyzed coal; Evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; Determine catalyst dispersion at high carbon conversion levels; Evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; Evaluate the recovery, regeneration and recycle of the spent catalysts; and Conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process.

Static delectric behavior of charged fluids near freezing

International Nuclear Information System (INIS)

Fasolino, A.; Parrinello, M.; Tosi, M.P.

1978-01-01

The wavenumber-dependent, static dielectric function of classical charged fluids near freezing is obtained from structural data based on computer simulation or neutron diffraction, and its behavior is connected with the freezing process. (Auth.)

Cryogenic freezing of fresh date fruits for quality preservation during frozen storage

Directory of Open Access Journals (Sweden)

Abdullah Alhamdan

2018-01-01

Full Text Available Fresh date fruits, especially Barhi cultivar, are favored and widely consumed at the Khalal maturity stage (first color edible stage. These fruits are seasonal and perishable and there is a need for extending their shelf life. This study evaluates two different freezing methods, namely cryogenic freezing using liquid nitrogen and conventional deep freezing on preserving the quality and stability of date fruits (cv. Barhi at Khalal maturity stage. Fresh date fruits (cv. Barhi at Khalal stage were frozen utilizing the two methods. The produced frozen dates were stored under frozen storage conditions for nine months (at −20 °C and −40 °C for the conventional and cryogenic freezing, respectively. Color values, textural properties (hardness, elasticity, chewiness and resilience, and nutrition attributes (enzymes and sugars for fresh dates before freezing and for the frozen dates were measured every three months during the frozen storage. Color values of the frozen dates were affected by the freezing method and the frozen storage period. There are substantial differences in the quality of the frozen fruits in favor of cryogenic freezing compared to the conventional slow freezing. The results revealed a large disparity between the times of freezing of the two methods. The freezing time accounted to 10 min in the cryogenic freezing method, whereas it was 1800 min for the conventional slow freezing system.

Stabilizing Effects of Deep Eutectic Solvents on Alcohol Dehydrogenase Mediated Systems

OpenAIRE

Fatima Zohra Ibn Majdoub Hassani; Ivan Lavandera; Joseph Kreit

2016-01-01

This study explored the effects of different organic solvents, temperature, and the amount of glycerol on the alcohol dehydrogenase (ADH)-catalysed stereoselective reduction of different ketones. These conversions were then analyzed by gas chromatography. It was found that when the amount of deep eutectic solvents (DES) increases, it can improve the stereoselectivity of the enzyme although reducing its ability to convert the substrate into the corresponding alcohol. Moreover, glycerol was fou...

Effect of cellulose nanocrystals (CNC) on rheological and mechanical properties and crystallization behavior of PLA/CNC nanocomposites.

Science.gov (United States)

Kamal, Musa R; Khoshkava, Vahid

2015-06-05

In earlier work, we reported that spray freeze drying of cellulose nanocrystals (CNC) yields porous agglomerate structures. On the other hand, the conventional spray dried CNC (CNCSD) and the freeze dried CNC (CNCFD) produce compact solid structures with very low porosity. As it is rather difficult to obtain direct microscopic evidence of the quality of dispersion of CNC in polymer nanocomposites, it was shown that supporting evidence of the quality and influence of dispersion in a polypropylene (PP)/CNC nanocomposite could be obtained by studying the rheological behavior, mechanical properties and crystallization characteristics of PP/CNC nanocomposites. In an effort to produce a sustainable, fully biosourced, biodegradable nanocomposite, this manuscript presents the results of a study of the rheological, mechanical and crystallization behavior of PLA/CNCSFD nanocomposites obtained by melt processing. The results are analyzed to determine CNC network formation, rheological percolation threshold concentrations, mechanical properties in the rubbery and glassy states, and the effect of CNCSFD on crystalline nucleation and crystallization rates of PLA. These results suggest that the porosity and network structure of CNCSFD agglomerates contribute significantly to good dispersion of CNC in the PLA matrix. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

Kiani, Hossein; Zhang, Zhihang; Sun, Da-Wen

2015-09-01

In recent years, innovative methods such as ultrasound assisted freezing have been developed in order to improve the freezing process. During freezing of foods, accurate prediction of the temperature distribution, phase ratios, and process time is very important. In the present study, ultrasound assisted immersion freezing process (in 1:1 ethylene glycol-water solution at 253.15K) of potato spheres (0.02 m diameter) was evaluated using experimental, numerical and analytical approaches. Ultrasound (25 kHz, 890 W m(-2)) was irradiated for different duty cycles (DCs=0-100%). A finite volume based enthalpy method was used in the numerical model, based on which temperature and liquid fraction profiles were simulated by a program developed using OpenFOAM® CFD software. An analytical technique was also employed to calculate freezing times. The results showed that ultrasound irradiation could decrease the characteristic freezing time of potatoes. Since ultrasound irradiation increased the heat transfer coefficient but simultaneously generated heat at the surface of the samples, an optimum DC was needed for the shortest freezing time which occurred in the range of 30-70% DC. DCs higher than 70% increased the freezing time. DCs lower than 30% did not provide significant effects on the freezing time compared to the control sample. The numerical model predicted the characteristic freezing time in accordance with the experimental results. In addition, analytical calculation of characteristic freezing time exhibited qualitative agreement with the experimental results. As the numerical simulations provided profiles of temperature and water fraction within potatoes frozen with or without ultrasound, the models can be used to study and control different operation situations, and to improve the understanding of the freezing process. Copyright © 2015 Elsevier B.V. All rights reserved.

Freeze-drying and related preparation techniques for biological microprobe analysis