One-, two- and three-phase viscosity treatments for basaltic lava flows

PubMed Central

Harris, Andrew J. L.; Allen, John S.

2009-01-01

Lava flows comprise three-phase mixtures of melt, crystals, and bubbles. While existing one-phase treatments allow melt phase viscosity to be assessed on the basis of composition, water content, and/or temperature, two-phase treatments constrain the effects of crystallinity or vesicularity on mixture viscosity. However, three-phase treatments, allowing for the effects of coexisting crystallinity and vesicularity, are not well understood. We investigate existing one- and two-phase treatments using lava flow case studies from Mauna Loa (Hawaii) and Mount Etna (Italy) and compare these with a three-phase treatment that has not been applied previously to basaltic mixtures. At Etna, melt viscosities of 425 ± 30 Pa s are expected for well-degassed (0.1 w. % H2O), and 135 ± 10 Pa s for less well-degassed (0.4 wt % H2O), melt at 1080°C. Application of a three-phase model yields mixture viscosities (45% crystals, 25–35% vesicles) in the range 5600–12,500 Pa s. This compares with a measured value for Etnean lava of 9400 ± 1500 Pa s. At Mauna Loa, the three-phase treatment provides a fit with the full range of field measured viscosities, giving three-phase mixture viscosities, upon eruption, of 110–140 Pa s (5% crystals, no bubble effect due to sheared vesicles) to 850–1400 Pa s (25–30% crystals, 40–60% spherical vesicles). The ability of the three-phase treatment to characterize the full range of melt-crystal-bubble mixture viscosities in both settings indicates the potential of this method in characterizing basaltic lava mixture viscosity. PMID:21691456

Shock Propagation In Crustal Rock

DTIC Science & Technology

1991-04-29

liquid produced above the melting point during unloading. Figure 5 displays calculations of release adiabats in the mixed phase regime based on the...muscovite [Bridgman, 1949]. The zero-pressure densities at points 1, 2 and 3 correspond to mixtures of orthoclase + A1203+H20, of wadeite + kyanite ...shocked tantalum and the high pressure melting point , in Shock Waves in Condensed Matter-1983, edited by J. R. Asay, R. A. Graham and G. K. Straub, pp. 91

Corrosion Testing of Zirconia, Beryllia and Magnesia Ceramics in Molten Alkali Metal Carbonates at 900°C

NASA Astrophysics Data System (ADS)

Kaplan, Valery; Lubomirsky, Igor

An electrochemical cell containing molten Li2CO3-Li2O has been proposed for the conversion of the greenhouse gas CO2 to CO, which can then either be used to power gas turbines or converted to methanol. Since efficient electrolysis takes place at 900°C, the materials which can be used in such a cell must satisfy stringent requirements. In the current work, we have examined the static corrosion resistance of zirconia, beryllia and magnesia ceramics at 900°C in the Li2CO3-Li2O mixture and in a Li-Na-K carbonate eutectic mixture with the ultimate objective of identifying suitable electrically insulating materials. Conclusions regarding material stability were based on elemental analysis of the melt, primarily via X-ray photoelectron spectroscopy, a particularly sensitive technique. It was found that magnesia is completely stable for at least 33 hrs in a Li2CO3-Li2O melt, while a combined lithium titanate/lithium zirconate layer forms on the zirconia ceramic as detected by XRD. Under the same melt conditions, beryllia shows considerable leaching into solution. In a Li-Na-K carbonate eutectic mixture containing 10.2 mol% oxide at 900°C under standard atmospheric conditions, magnesia showed no signs of degradation. Stabilization of the zirconia content of the eutectic mixture at 0.01-0.02 at% after 2 hrs is again explained by the formation of a lithium titanate/ lithium zirconate coating. On the basis of these results, we conclude that only magnesia can be satisfactorily used as an insulating material in electrolysis cells containing Li2CO3-Li2O melts.

Thermodynamic Investigation of the Eutectic Mixture of the LiNO3-NaNO3-KNO3-Ca(NO3)2 System

NASA Astrophysics Data System (ADS)

Peng, Qiang; Ding, Jing; Wei, Xiaolan; Jiang, Gan

2017-09-01

Molten nitrate salt is usually employed as heat transfer or energy storage medium in concentrating solar power systems to improve the overall efficiency of thermoelectric conversion. In the present work, the liquidus curves of the LiNO3-NaNO3-KNO3-Ca(NO3)2 system is determined by conformal ionic solution theory according to the solid-liquid equilibrium state of the binary mixture. The calculated eutectic temperature of the mixture is 93.17 {°}C, which is close to the experimental value of 93.22 {°}C obtained from differential scanning calorimetry (DSC). Visualization observation experiments reveal that the quaternary eutectic mixture begins to partially melt when the temperature reaches 50 {°}C, and the degree of melting increases with temperature. The mixture is completely melted at 130 {°}C. The observed changes in the dissolved state at different temperatures correlate well with the DSC heat flow curve fluctuations.

Polymorphic Transformation in Mixtures of High- and Low-Melting Fractions of Milk Fat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cisneros,A.; Mazzanti, G.; Campos, R.

2006-01-01

The kinetics of crystallization of high-melting fraction (HMF) and a mixture of 40% HMF and 60% low-melting fraction (LMF) of milk fat were studied at 5 C by time-resolved in-situ synchrotron X-ray diffraction. HMF crystallized in the {alpha} polymorph, had a longer lifetime than the ones previously reported in pure milk fat, and was almost completely solid. The HMF/LMF mixture crystallized initially in the {alpha} form and transformed into the {beta}' polymorph, with a solid fat content much lower than that of HMF. The polymorphic change was therefore attributed to a delayed sudden formation of {beta}' mixed crystals from themore » uncrystallized melt. These findings are important for the food industry and as fundamental knowledge to improve our understanding of the origin of the macroscopic physical properties of solid milk fat fractions used in many manufacturing processes.« less

Rheology as a tool for evaluation of melt processability of innovative dosage forms.

PubMed

Aho, Johanna; Boetker, Johan P; Baldursdottir, Stefania; Rantanen, Jukka

2015-10-30

Future manufacturing of pharmaceuticals will involve innovative use of polymeric excipients. Hot melt extrusion (HME) is an already established manufacturing technique and several products based on HME are on the market. Additionally, processing based on, e.g., HME or three dimensional (3D) printing, will have an increasingly important role when designing products for flexible dosing, since dosage forms based on compacting of a given powder mixture do not enable manufacturing of optimal pharmaceutical products for personalized treatments. The melt processability of polymers and API-polymer mixtures is highly dependent on the rheological properties of these systems, and rheological measurements should be considered as a more central part of the material characterization tool box when selecting suitable candidates for melt processing by, e.g., HME or 3D printing. The polymer processing industry offers established platforms, methods, and models for rheological characterization, and they can often be readily applied in the field of pharmaceutical manufacturing. Thoroughly measured and calculated rheological parameters together with thermal and mechanical material data are needed for the process simulations which are also becoming increasingly important. The authors aim to give an overview to the basics of rheology and summarize examples of the studies where rheology has been utilized in setting up or evaluating extrusion processes. Furthermore, examples of different experimental set-ups available for rheological measurements are presented, discussing each of their typical application area, advantages and limitations. Copyright © 2015 Elsevier B.V. All rights reserved.

Characterization and Thermal Properties of Nitrate Based Molten Salt for Heat Recovery System

NASA Astrophysics Data System (ADS)

Faizal Tukimon, Mohd; Muhammad, Wan Nur Azrina Wan; Nor Annuar Mohamad, Md; Yusof, Farazila

2017-10-01

Molten salt can acts like a storage medium or heat transfer fluid in heat recovery system. Heat transfer fluid is a fluid that has the capability to deliver heat this one side to another while heat recovery system is a system that transfers heat to produce energy. This studies shows about determining the new formulation of different molten nitrate/nitrite salts consisting of LiNO3, KNO2, KNO3 and NaNO2 that give a low temperature of melting point and high average specific heat capacity. Mixed alkaline molten nitrate/nitrite salt can act as a heat transfer fluid due to their advantageous in terms of its properties that feasible in heat recovery system such as high specific heat capacity, low vapour pressure, low cost and wide range of temperature in its application. The mixing of these primary substances will form a new line of quaternary nitrate salt (LiNO3 - KNO2 - KNO3 - NaNO2). The quaternary mixture was heated inside the box furnace at 150°C for four hours and rose up the temperature to 400°C for eight hours to homogenize the mixture. Through heating process, the elements of nitrate/nitrite base were mixed completely. The temperature was then reduced to 115°C for several hours before removing the mixture from the furnace. The melting point of each sample were testified by using thermal gravimetric analysis, TGA/DTA and experiment of determining the specific heat capacity were conducted by using Differential Scanning Calorimeter, DSC. From the result, it is found that the melting point Sample 1 with percentage of weightage (25.4wt% of LiNO3, 33.8wt% of KNO2, 20.7wt% of KNO3 and 20.1wt% of NaNO2) is 94.4°C whereas the average specific heat capacity was 1.0484/g°C while for Sample 3 with percentages of weightage (30.0wt% of LiNO3, 50.2wt% of KNO2, 3.1wt% of KNO3 and 16.7wt% of NaNO2), the melting point is 86.1°C with average specific heat capacity of 0.7274 J/g°C. In the nut shell, the quaternary mixture salts had been a good mixture with good thermal properties that low in melting point and have high specific heat capacity which could be a potential heat transfer fluid in heat recovery application.

Corrosion testing of zirconia, beryllia and magnesia ceramics in molten alkali metal carbonates at 900 °C

NASA Astrophysics Data System (ADS)

Kaplan, Valery; Bendikov, Tatyana; Feldman, Yishay; Gartsman, Konstantin; Wachtel, Ellen; Lubomirsky, Igor

2016-01-01

An electrochemical cell containing molten Li2CO3-Li2O at 900 °C has been proposed for the conversion of the greenhouse gas CO2 to CO for chemical energy storage. In the current work, we have examined the corrosion resistance of zirconia, beryllia and magnesia ceramics at 900 °C in the Li2CO3-Li2O and Li-Na-K carbonate eutectic mixtures to identify suitable electrically insulating materials. Conclusions regarding material stability were based on elemental analysis of the melt, primarily via X-ray photoelectron spectroscopy, a particularly sensitive technique. It was found that magnesia is completely stable for at least 33 h in a Li2CO3-Li2O melt, while a combined lithium titanate/lithium zirconate layer forms on the zirconia ceramic as detected by XRD. Under the same melt conditions, beryllia shows considerable leaching into solution. In a Li-Na-K carbonate eutectic mixture containing 10.2 mol% oxide at 900 °C under standard atmospheric conditions, magnesia showed no signs of degradation. Stabilization of the zirconia content of the eutectic mixture at 0.01-0.02 at% after 2 h is explained by the formation of a lithium zirconate coating on the ceramic. On the basis of these results, we conclude that only magnesia can be satisfactorily used as an insulating material in electrolysis cells containing Li2CO3-Li2O melts.

Coordinated Hard Sphere Mixture (CHaSM): A simplified model for oxide and silicate melts at mantle pressures and temperatures

NASA Astrophysics Data System (ADS)

Wolf, Aaron S.; Asimow, Paul D.; Stevenson, David J.

2015-08-01

We develop a new model to understand and predict the behavior of oxide and silicate melts at extreme temperatures and pressures, including deep mantle conditions like those in the early Earth magma ocean. The Coordinated Hard Sphere Mixture (CHaSM) is based on an extension of the hard sphere mixture model, accounting for the range of coordination states available to each cation in the liquid. By utilizing approximate analytic expressions for the hard sphere model, this method is capable of predicting complex liquid structure and thermodynamics while remaining computationally efficient, requiring only minutes of calculation time on standard desktop computers. This modeling framework is applied to the MgO system, where model parameters are trained on a collection of crystal polymorphs, producing realistic predictions of coordination evolution and the equation of state of MgO melt over a wide range of pressures and temperatures. We find that the typical coordination number of the Mg cation evolves continuously upward from 5.25 at 0 GPa to 8.5 at 250 GPa. The results produced by CHaSM are evaluated by comparison with predictions from published first-principles molecular dynamics calculations, indicating that CHaSM is accurately capturing the dominant physics controlling the behavior of oxide melts at high pressure. Finally, we present a simple quantitative model to explain the universality of the increasing Grüneisen parameter trend for liquids, which directly reflects their progressive evolution toward more compact solid-like structures upon compression. This general behavior is opposite that of solid materials, and produces steep adiabatic thermal profiles for silicate melts, thus playing a crucial role in magma ocean evolution.

Ratio

NASA Astrophysics Data System (ADS)

Webster, Nathan A. S.; Pownceby, Mark I.; Madsen, Ian C.; Studer, Andrew J.; Manuel, James R.; Kimpton, Justin A.

2014-12-01

Effects of basicity, B (CaO:SiO2 ratio) on the thermal range, concentration, and formation mechanisms of silico-ferrite of calcium and aluminum (SFCA) and SFCA-I iron ore sinter bonding phases have been investigated using an in situ synchrotron X-ray diffraction-based methodology with subsequent Rietveld refinement-based quantitative phase analysis. SFCA and SFCA-I phases are the key bonding materials in iron ore sinter, and improved understanding of the effects of processing parameters such as basicity on their formation and decomposition may assist in improving efficiency of industrial iron ore sintering operations. Increasing basicity significantly increased the thermal range of SFCA-I, from 1363 K to 1533 K (1090 °C to 1260 °C) for a mixture with B = 2.48, to ~1339 K to 1535 K (1066 °C to 1262 °C) for a mixture with B = 3.96, and to ~1323 K to 1593 K (1050 °C to 1320 °C) at B = 4.94. Increasing basicity also increased the amount of SFCA-I formed, from 18 wt pct for the mixture with B = 2.48 to 25 wt pct for the B = 4.94 mixture. Higher basicity of the starting sinter mixture will, therefore, increase the amount of SFCA-I, considered to be more desirable of the two phases. Basicity did not appear to significantly influence the formation mechanism of SFCA-I. It did, however, affect the formation mechanism of SFCA, with the decomposition of SFCA-I coinciding with the formation of a significant amount of additional SFCA in the B = 2.48 and 3.96 mixtures but only a minor amount in the highest basicity mixture. In situ neutron diffraction enabled characterization of the behavior of magnetite after melting of SFCA produced a magnetite plus melt phase assemblage.

Solid-liquid phase coexistence of alkali nitrates from molecular dynamics simulations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jayaraman, Saivenkataraman

2010-03-01

Alkali nitrate eutectic mixtures are finding application as industrial heat transfer fluids in concentrated solar power generation systems. An important property for such applications is the melting point, or phase coexistence temperature. We have computed melting points for lithium, sodium and potassium nitrate from molecular dynamics simulations using a recently developed method, which uses thermodynamic integration to compute the free energy difference between the solid and liquid phases. The computed melting point for NaNO3 was within 15K of its experimental value, while for LiNO3 and KNO3, the computed melting points were within 100K of the experimental values [4]. We aremore » currently extending the approach to calculate melting temperatures for binary mixtures of lithium and sodium nitrate.« less

Method of Preparing Polymers with Low Melt Viscosity

NASA Technical Reports Server (NTRS)

Jensen, Brian J. (Inventor)

2001-01-01

This invention is an improvement in standard polymerizations procedures, i.e., addition-type and step-growth type polymerizations, wherein monomers are reacted to form a growing polymer chain. The improvement includes employing an effective amount of a trifunctional monomer (such as a trifunctional amine anhydride, or phenol) in the polymerization procedure to form a mixture of polymeric materials consisting of branced polymers, star-shaped polymers, and linear polymers. This mixture of polymeric materials has a lower melt temperature and a lower melt viscosity than corresponding linear polymeric materials of equivalent molecular weight.

Quality improvement of melt extruded laminar systems using mixture design.

PubMed

Hasa, D; Perissutti, B; Campisi, B; Grassi, M; Grabnar, I; Golob, S; Mian, M; Voinovich, D

2015-07-30

This study investigates the application of melt extrusion for the development of an oral retard formulation with a precise drug release over time. Since adjusting the formulation appears to be of the utmost importance in achieving the desired drug release patterns, different formulations of laminar extrudates were prepared according to the principles of Experimental Design, using a design for mixtures to assess the influence of formulation composition on the in vitro drug release from the extrudates after 1h and after 8h. The effect of each component on the two response variables was also studied. Ternary mixtures of theophylline (model drug), monohydrate lactose and microcrystalline wax (as thermoplastic binder) were extruded in a lab scale vertical ram extruder in absence of solvents at a temperature below the melting point of the binder (so that the crystalline state of the drug could be maintained), through a rectangular die to obtain suitable laminar systems. Thanks to the desirability approach and a reliability study for ensuring the quality of the formulation, a very restricted optimal zone was defined within the experimental domain. Among the mixture components, the variation of microcrystalline wax content played the most significant role in overall influence on the in vitro drug release. The formulation theophylline:lactose:wax, 57:14:29 (by weight), selected based on the desirability zone, was subsequently used for in vivo studies. The plasma profile, obtained after oral administration of the laminar extruded system in hard gelatine capsules, revealed the typical trend of an oral retard formulation. The application of the mixture experimental design associated to a desirability function permitted to optimize the extruded system and to determine the composition space that ensures final product quality. Copyright © 2015 Elsevier B.V. All rights reserved.

Determination of Activities of Niobium in Cu-Nb Melts Containing Dilute Nb

NASA Astrophysics Data System (ADS)

Wang, Daya; Yan, Baijun; Sichen, Du

2015-04-01

The activity coefficients of niobium in Cu-Nb melts were measured by equilibrating solid NbO2 with liquid copper under controlled oxygen potentials in the temperature range of 1773 K to 1898 K (1500 °C to 1625 °C). Either CO-CO2 gas mixture or H2-CO2 gas mixture was employed to obtain the desired oxygen partial pressures. Cu-Nb system was found to follow Henry's law in the composition range studied. The temperature dependence of Henry's constant in the Cu-Nb melts could be expressed as follows: The partial molar excess Gibbs energy change of niobium in Cu-Nb melts can be expressed as follows:

Novel duplex vapor-electrochemical method for silicon solar cells

NASA Technical Reports Server (NTRS)

Nanis, L.; Sanjurjo, A.; Sancier, K. M.; Kapur, V. K.; Bartlett, R. W.; Westphal, S.

1980-01-01

A process was developed for the economic production of high purity Si from inexpensive reactants, based on the Na reduction of SiF4 gas. The products of reaction (NaF, Si) are separated by either aqueous leaching or by direct melting of the NaF-Si product mixture. Impurities known to degrade solar cell performance are all present at sufficiently low concentrations so that melt solidification (e.g., Czochralski) will provide a silicon material suitable for solar cells.

Melting icebergs to produce fresh water and mechanical energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Camirand, W.M.; Hautala, E.; Randall, J.M.

1981-10-20

Fresh water and mechanical energy are obtained from melting of icebergs. Warm surface seawater is contacted with a fluid, which is vaporized. The resulting vapor is used to generate mechanical energy and then is condensed by contacting it with cold melt water from the iceberg. The fluid is regenerated with a concomitant elevation in the temperature of the melt water. The warmer melt water is cycled to the body of the iceberg to facilitate its melting and produce additional cold melt water, which is apportioned as fresh water and water cycled to condense the aforesaid vapor. In an alternate embodimentmore » of the invention warm seawater is evaporated at reduced pressure. Mechanical energy is generated from the vapor, which is then condensed by direct and intimate contact with cold melt water from the iceberg. The resultant fresh water is a mixture of condensed vapor and melt water from the iceberg and has a temperature greater than the cold melt water. This fresh water mixture is contacted with the body of the iceberg to further melt it; part of the cold melt water is separated as fresh water and the remainder is cycled for use in condensing the vapor from the warm surface seawater.« less

Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis

PubMed Central

Huang, Jingyu; Lu, Shilei; Kong, Xiangfei; Liu, Shangbao; li, Yiran

2013-01-01

This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs), based on eutectic mixtures as phase change materials (PCMs) for thermal energy storage and high-density polyethylene (HDPE)-ethylene-vinyl acetate (EVA) polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD)–capric acid (CA), TD–lauric acid (LA), and TD–myristic acid (MA), which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC). The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD–CA PCM), 24.53 °C/24.92 °C (FS TD–LA PCM), and 33.15 °C/30.72 °C (FS TD–MA PCM), respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP). It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties. PMID:28788358

Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis.

PubMed

Huang, Jingyu; Lu, Shilei; Kong, Xiangfei; Liu, Shangbao; Li, Yiran

2013-10-22

This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs), based on eutectic mixtures as phase change materials (PCMs) for thermal energy storage and high-density polyethylene (HDPE)-ethylene-vinyl acetate (EVA) polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD)-capric acid (CA), TD-lauric acid (LA), and TD-myristic acid (MA), which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC). The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD-CA PCM), 24.53 °C/24.92 °C (FS TD-LA PCM), and 33.15 °C/30.72 °C (FS TD-MA PCM), respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP). It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

Densities of some molten fluoride salt mixtures suitable for heat storage in space power applications

NASA Technical Reports Server (NTRS)

Misra, Ajay K.

1988-01-01

Liquid densities were determined for a number of fluoride salt mixtures suitable for heat storage in space power applications, using a procedure that consisted of measuring the loss of weight of an inert bob in the melt. The density apparatus was calibrated with pure LiF and NaF at different temperatures. Density data for safe binary and ternary fluoride salt eutectics and congruently melting intermediate compounds are presented. In addition, a comparison was made between the volumetric heat storage capacity of different salt mixtures.

Separation of non-racemic mixtures of enantiomers: an essential part of optical resolution.

PubMed

Faigl, Ferenc; Fogassy, Elemér; Nógrádi, Mihály; Pálovics, Emese; Schindler, József

2010-03-07

Non-racemic enantiomeric mixtures form homochiral and heterochiral aggregates in melt or suspension, during adsorption or recrystallization, and these diastereomeric associations determine the distribution of the enantiomers between the solid and other (liquid or vapour) phases. That distribution depends on the stability order of the homo- and heterochiral aggregates (conglomerate or racemate formation). Therefore, there is a correlation between the binary melting point phase diagrams and the experimental ee(I)vs. ee(0) curves (ee(I) refers to the crystallized enantiomeric mixtures, ee(0) is the composition of the starting ones). Accordingly, distribution of the enantiomeric mixtures between two phases is characteristic and usually significant enrichment can be achieved. There are two exceptions: no enrichment could be observed under thermodynamically controlled conditions when the starting enantiomer composition corresponded to the eutectic composition, or when the method used was unsuitable for separation. In several cases, when kinetic control governed the crystallization, the character of the ee(0)-ee(I) curve did not correlate with the melting point binary phase diagram.

Rheological and thermal performance of newly developed binder systems for ceramic injection molding

NASA Astrophysics Data System (ADS)

Hausnerova, Berenika; Kasparkova, Vera; Hnatkova, Eva

2016-05-01

In a novel binder system, carnauba wax was considered to replace the synthetic backbone polymers (polyolefins) enhancing the environmental sustainability of Ceramic Injection Molding (CIM) technology. The paper presents comparison of the rheological performance and thermal behavior of the aluminum oxide CIM feedstocks based on a binder containing carnauba wax with those consisting of a commercial binder. Further, acrawax (N, N'-Ethylene Bis-stearamide) has been considered as another possible substitute of polyolefins. For both proposed substitutes there is a significant reduction in viscosity, and in case of carnauba wax based feedstock also in processing temperature, which is essential for injection molding of reactive powders. Thermal characterization comprised analyses of single neat binders, their mixtures and mixtures with aluminum oxide. The presence of powder lowered melting temperatures of all tested binders except of polyolefin. Further depression in melting point of poly(ethylene glycol) is observed in combination with polyolefin in the presence of powder, and it is related to changes in size of the crystalline domains.

[A DNA study of rat liver oligonucleosomes enriched by transcriptionally active genes during induction due to the administration of an amino acid mixture].

PubMed

Vardevanian, P O; Davtian, A M; Tiratsuian, S G; Vardevanian, A O

1990-01-01

A highly active fraction of rat liver oligonucleosome DNA has been isolated and studied by means of thermal denaturation after induction by amino acid mixture or hydrocortisone. A considerable redistribution of DNA content has been shown in sucrose gradient fractions during these forms of induction. The changes are revealed in melting temperature, differential melting profile of DNA, isolated from actively transcribed chromatine fractions. Analysis of melting profiles shows changes of GC content of oligonucleosome DNA, suggesting that there are differences in activation during two studied forms of induction.

Method for harvesting rare earth barium copper oxide single crystals

DOEpatents

Todt, V.R.; Sengupta, S.; Shi, D.

1996-04-02

A method of preparing high temperature superconductor single crystals is disclosed. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid. 2 figs.

Method for harvesting rare earth barium copper oxide single crystals

DOEpatents

Todt, Volker R.; Sengupta, Suvankar; Shi, Donglu

1996-01-01

A method of preparing high temperature superconductor single crystals. The method of preparation involves preparing precursor materials of a particular composition, heating the precursor material to achieve a peritectic mixture of peritectic liquid and crystals of the high temperature superconductor, cooling the peritectic mixture to quench directly the mixture on a porous, wettable inert substrate to wick off the peritectic liquid, leaving single crystals of the high temperature superconductor on the porous substrate. Alternatively, the peritectic mixture can be cooled to a solid mass and reheated on a porous, inert substrate to melt the matrix of peritectic fluid while leaving the crystals melted, allowing the wicking away of the peritectic liquid.

Staged mold for encapsulating hazardous wastes

DOEpatents

Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

1990-01-01

A staged mold for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

Staged mold for encapsulating hazardous wastes

DOEpatents

Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

1988-01-01

A staged mold for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

Method for encapsulating hazardous wastes using a staged mold

DOEpatents

Unger, Samuel L.; Telles, Rodney W.; Lubowitz, Hyman R.

1989-01-01

A staged mold and method for stabilizing hazardous wastes for final disposal by molding an agglomerate of the hazardous wastes and encapsulating the agglomerate. Three stages are employed in the process. In the first stage, a first mold body is positioned on a first mold base, a mixture of the hazardous wastes and a thermosetting plastic is loaded into the mold, the mixture is mechanically compressed, heat is applied to cure the mixture to form a rigid agglomerate, and the first mold body is removed leaving the agglomerate sitting on the first mold base. In the second stage, a clamshell second mold body is positioned around the agglomerate and the first mold base, a powdered thermoplastic resin is poured on top of the agglomerate and in the gap between the sides of the agglomerate and the second mold body, the thermoplastic is compressed, heat is applied to melt the thermoplastic, and the plastic is cooled jacketing the agglomerate on the top and sides. In the third stage, the mold with the jacketed agglomerate is inverted, the first mold base is removed exposing the former bottom of the agglomerate, powdered thermoplastic is poured over the former bottom, the first mold base is replaced to compress the thermoplastic, heat is applied to melt the new thermoplastic and the top part of the jacket on the sides, the plastic is cooled jacketing the bottom and fusing with the jacketing on the sides to complete the seamless encapsulation of the agglomerate.

Improved Heat-of-Fusion Energy Storage

NASA Technical Reports Server (NTRS)

Chen, K. H.; Manvi, R.

1982-01-01

Alkali metal/alkali-halide mixtures proposed for preventing solid buildup during energy recovery. When mixture melts (by absorption of heat of fusion), it forms two immiscible liquids. Salt-rich phase is heavier and has higher melting/recrysallization temperature; so during energy recovery salt crystallizes in this phase first. Since heat exchanger for energy recovery is in lighter metal-rich phase, solids do not form and there is no reduction of heat-recovery efficiency.

Anisotropic surface melting in lyotropic cubic crystals: part 2: facet-by-facet melting at Ia3d/vapor interfaces.

PubMed

Leroy, S; Grenier, J; Rohe, D; Even, C; Pieranski, P

2006-05-01

From experiments with metal crystals, in the vicinity of their crystal/liquid/vapor triple points, it is known that melting of crystals starts on their surfaces and is anisotropic. Recently, we have shown that anisotropic surface melting occurs also in lyotropic systems. In our previous paper (Eur. Phys. J. E 19, 223 (2006)), we have focused on the case of poor faceting at the Pn3m/L1 interface in C12EO2/water binary mixtures. There anisotropic melting occurs in the vicinity of a Pn3m/L3/L1 triple point. In the present paper, we focus on the opposite case of a rich devil's-staircase-type faceting at Ia3d/vapor interfaces in monoolein/water and phytantriol/water mixtures. We show that anisotropic surface melting takes place in these systems in a narrow humidity range close to the Ia3d-L2 transition. As whole (hkl) sets of facets disappear one after another when the transition is approached, surface melting occurs in a facet-by-facet type.

Construction of a Cr3C2-C Peritectic Point Cell for Thermocouple Calibration

NASA Astrophysics Data System (ADS)

Ogura, Hideki; Deuze, Thierry; Morice, Ronan; Ridoux, Pascal; Filtz, Jean-Remy

The melting points of Cr3C2-C peritectic (1826°C) and Cr7C3-Cr3C2 eutectic (1742°C) alloys as materials for high-temperature fixed point cells are investigated for the use of thermocouple calibration. Pretests are performed to establish a suitable procedure for constructing contact thermometry cells based on such chromium-carbon mixtures. Two cells are constructed following two different possible procedures. The above two melting points are successfully observed for one of these cells using tungsten-rhenium alloy thermocouples.

Chemical fractionation of siderophile elements in impactites from Australian meteorite craters

NASA Technical Reports Server (NTRS)

Attrep, A., Jr.; Orth, C. J.; Quintana, L. R.; Shoemaker, C. S.; Shoemaker, E. M.; Taylor, S. R.

1991-01-01

The abundance pattern of siderophile elements in terrestrial and lunar impact melt rocks was used extensively to infer the nature of the impacting projectiles. An implicit assumption made is that the siderophile abundance ratios of the projectiles are approximately preserved during mixing of the projectile constituents with the impact melts. As this mixture occurs during flow of strongly shocked materials at high temperatures, however there are grounds for suspecting that the underlying assumption is not always valid. In particular, fractionation of the melted and partly vaporized material of the projectile might be expected because of differences in volatility, solubility in silicate melts, and other characteristics of the constituent elements. Impactites from craters with associated meteorites offer special opportunities to test the assumptions on which projectile identifications are based and to study chemical fractionation that occurred during the impact process.

Research and Development of EDDN and DETN at Pilot Scale

DTIC Science & Technology

2009-07-17

based fills which fails to meet Insensitive Munitions (1M) requirements. These formulations are based upon a nitrate salt based eutectic mixture...155mm M795 artillery projectile. Two components of this DEMN eutectic are the energetic salts , Ethylenediamine 15. SUBJECT TERMS EDDN, DETN, DEMN...need, ARL has been developing a series of reduced sensitivity melt cast explosive formulations that are based on the nitrate salt containing eutectic

Glass ceramic toughened with tetragonal zirconia

DOEpatents

Keefer, K.D.

1984-02-10

A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nuclearing agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200 to 1700/sup 0/C and is then heat-treated at a temperature within the range of 800 to 1200/sup 0/C in order to precipitate tetragonal ZrO/sub 2/. The composition, as well as the length and temperature of the heat treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

Glass ceramic toughened with tetragonal zirconia

DOEpatents

Keefer, Keith D.; Michalske, Terry A.

1986-01-01

A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat-treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nucleating agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200.degree. to 1700.degree. C. and is then heat-treated at a temperature within the range of 800.degree. to 1200.degree. C. in order to precipitate tetragonal ZrO.sub.2. The composition, as well as the length and temperature of the heat-treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

Metal-halide mixtures for latent heat energy storage

NASA Technical Reports Server (NTRS)

Chen, K.; Manvi, R.

1981-01-01

Alkali metal and alkali halide mixtures are identified which may be suitable for thermal energy storage at temperatures above 600 C. The use of metal-halides is appropriate because of their tendency to form two immiscible melts with a density difference, which reduces scale formation and solidification on heat transfer surfaces. Also, the accumulation of phase change material along the melt interface is avoided by the self-dispersing characteristic of some metal-halides, in particular Sr-SrCl2, Ba-BaCl2, and Ba-BaBr2 mixtures. Further advantages lie in their high thermal conductivities, ability to cope with thermal shock, corrosion inhibition, and possibly higher energy densities.

High-Melting Lipid Mixtures and the Origin of Detergent-Resistant Membranes Studied with Temperature-Solubilization Diagrams

PubMed Central

Sot, Jesús; Manni, Marco M.; Viguera, Ana R.; Castañeda, Verónica; Cano, Ainara; Alonso, Cristina; Gil, David; Valle, Mikel; Alonso, Alicia; Goñi, Félix M.

2014-01-01

The origin of resistance to detergent solubilization in certain membranes, or membrane components, is not clearly understood. We have studied the solubilization by Triton X-100 of binary mixtures composed of egg sphingomyelin (SM) and either ceramide, diacylglycerol, or cholesterol. Solubilization has been assayed in the 4–50°C range, and the results are summarized in a novel, to our knowledge, form of plots, that we have called temperature-solubilization diagrams. Despite using a large detergent excess (lipid/detergent 1:20 mol ratio) and extended solubilization times (24–48 h) certain mixtures were not amenable to Triton X-100 solubilization at one or more temperatures. DSC of all the lipid mixtures, and of all the lipid + detergent mixtures revealed that detergent resistance was associated with the presence of gel domains at the assay temperature. Once the system melted down, solubilization could occur. In general adding high-melting lipids limited the solubilization, whereas the addition of low-melting lipids promoted it. Lipidomic analysis of Madin-Darby canine kidney cell membranes and of the corresponding detergent-resistant fraction indicated a large enrichment of the nonsolubilized components in saturated diacylglycerol and ceramide. SM-cholesterol mixtures were special in that detergent solubilization was accompanied, for certain temperatures and compositions, by an independent phenomenon of reassembly of the partially solubilized lipid bilayers. The temperature at which lysis and reassembly prevailed was ∼25°C, thus for some SM-cholesterol mixtures solubilization occurred both above and below 25°C, but not at that temperature. These observations can be at the origin of the detergent resistance effects observed with cell membranes, and they also mean that cholesterol-containing detergent-resistant membrane remnants cannot correspond to structures existing in the native membrane before detergent addition. PMID:25517149

Modeling of two-phase porous flow with damage

NASA Astrophysics Data System (ADS)

Cai, Z.; Bercovici, D.

2009-12-01

Two-phase dynamics has been broadly studied in Earth Science in a convective system. We investigate the basic physics of compaction with damage theory and present preliminary results of both steady state and time-dependent transport when melt migrates through porous medium. In our simple 1-D model, damage would play an important role when we consider the ascent of melt-rich mixture at constant velocity. Melt segregation becomes more difficult so that porosity is larger than that in simple compaction in the steady-state compaction profile. Scaling analysis for compaction equation is performed to predict the behavior of melt segregation with damage. The time-dependent of the compacting system is investigated by looking at solitary wave solutions to the two-phase model. We assume that the additional melt is injected to the fracture material through a single pulse with determined shape and velocity. The existence of damage allows the pulse to keep moving further than that in simple compaction. Therefore more melt could be injected to the two-phase mixture and future application such as carbon dioxide injection is proposed.

Selective laser sintering of cermet mixtures Ti and B4C

NASA Astrophysics Data System (ADS)

Filippov, A. A.; Fomin, V. M.; Malikov, A. G.; Orishich, A. M.

2016-10-01

The work is dedicated to the creation of a new heterogeneous ceramic-composite materials based on boron carbide and titanium, using a laser, in order to further layer-growing 3D products from these materials. The paper discussed two methods for obtaining ceramic-composite material: laser sintering of boron carbide powder and a metal-melting the powder mixture. We study the microstructure of the samples at various energy process modes. An attempt was made to justify the applicability of the regime used for the cultivation of layered products.

Fabrication of high exposure nuclear fuel pellets

DOEpatents

Frederickson, James R.

1987-01-01

A method is disclosed for making a fuel pellet for a nuclear reactor. A mixture is prepared of PuO.sub.2 and UO.sub.2 powders, where the mixture contains at least about 30% PuO.sub.2, and where at least about 12% of the Pu is the Pu.sup.240 isotope. To this mixture is added about 0.3 to about 5% of a binder having a melting point of at least about 250.degree. F. The mixture is pressed to form a slug and the slug is granulated. Up to about 4.7% of a lubricant having a melting point of at least about 330.degree. F. is added to the granulated slug. Both the binder and the lubricant are selected from a group consisting of polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof. The mixture is pressed to form a pellet and the pellet is sintered.

XAFS Study on Chlorination of Y2O3 in LiCl-KCl-ZrCl4 Melt

NASA Astrophysics Data System (ADS)

Okamoto, Yoshihiro; Yaita, Tsuyoshi; Shiwaku, Hideaki; Suzuki, Shinichi

2008-11-01

The chlorination reaction of Y2O3 with ZrCl4 in LiCl-KCl eutectic melt was investigated by X-ray absorption fine structure (XAFS) technique. The chlorination reaction was observed between 773 K and 823 K as the 1st peak shift of the Fourier transform magnitude function |FT(k3χ(k))|. The peak corresponding to the nearest Y3+-Cl- correlation was observed in the XAFS analysis at 823 K as the result of the chlorination. It was confirmed that the mixture melts after the reaction is almost equivalent to a molten 5% YCl3-(LiCl-KCl eutectic) mixture.

Co-settling of Chromite and Sulfide Melt Droplets and Trace Element Partitioning between Sulfide and Silicate Melts

NASA Astrophysics Data System (ADS)

Manoochehri, S.; Schmidt, M. W.; Guenther, D.

2013-12-01

Gravitational settling of immiscible, dense sulfide melt droplets together with other cumulate phases such as chromite, combined with downward percolation of these droplets through a cumulate pile, is thought to be one of the possible processes leading to the formation of PGE rich sulfide deposits in layered mafic intrusions. Furthermore some chromitite seams in the Merensky Reef (Bushveld Complex) are considered to be acting as a filter or barrier for further downward percolation of sulfide melts into footwall layers. To investigate the feasibility of such mechanical processes and to study the partitioning behavior of 50 elements including transition metals and REEs (but not PGEs) between a silicate and a sulfide melt, two separate series of high temperature (1250-1380 °C) centrifuge-assisted experiments at 1000 g, 0.4-0.6 GPa were conducted. A synthetic silicate glass with a composition representative of the parental magma of the Bushveld Complex (~ 55 wt% SiO2) was mixed with pure FeS powder. For the first series of experiments, 15 or 25 wt% natural chromite with average grain sizes of ~ 5 or 31 μm were added to a mixture of silicate glass and FeS (10 wt%) adding 1 wt% water. For the second series, a mixture of the same glass and FeS was doped with 50 trace elements. These mixtures were first statically equilibrated and then centrifuged. In the first experimental series, sulfide melt droplets settled together with, but did not segregate from chromite grains even after centrifugation at 1000 g for 12 hours. A change in initial chromite grain size and proportions didn't have any effect on segregation. Without chromite, the starting mixture resulted in the formation of large sulfide melt pools together with finer droplets still disseminated through the silicate glass and both at the bottom of the capsule. The incomplete segregation of sulfide melt is interpreted as being due to high interfacial energies between sulfide and silicate melts/crystals which hinder both, the nucleation of newly formed sulfide droplets and the interconnectivity of separate droplets. The interfacial energies between sulfide melt and silicate or oxide crystals is even higher than for silicate melt, consequently in experiments with chromite, sulfide segregation is even more hindered. Partition coefficients of 50 elements between a sulfide and a silicate melt are determined as a function of differing temperature between 1250 - 1380 °C. As a proxy to investigate the bond strength of network modifier cations, the relation between the partition coefficients and ionic potentials of different groups of elements has been determined.

Polyimide processing additives

NASA Technical Reports Server (NTRS)

Fletcher, James C. (Inventor); Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Stoakley, Diane M. (Inventor); Burks, Harold D. (Inventor)

1992-01-01

A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly-(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15 percent by weight of additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA.

Polyimide processing additives

NASA Technical Reports Server (NTRS)

Pratt, J. Richard (Inventor); St.clair, Terry L. (Inventor); Stoakley, Diane M. (Inventor); Burks, Harold D. (Inventor)

1993-01-01

A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly-(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15 percent by weight of the additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA.

Effect of composition in the development of carbamazepine hot-melt extruded solid dispersions by application of mixture experimental design.

PubMed

Djuris, Jelena; Ioannis, Nikolakakis; Ibric, Svetlana; Djuric, Zorica; Kachrimanis, Kyriakos

2014-02-01

This study investigates the application of hot-melt extrusion for the formulation of carbamazepine (CBZ) solid dispersions, using polyethyleneglycol-polyvinyl caprolactam-polyvinyl acetate grafted copolymer (Soluplus, BASF, Germany) and polyoxyethylene-polyoxypropylene block copolymer (Poloxamer 407). In agreement with the current Quality by Design principle, formulations of solid dispersions were prepared according to a D-optimal mixture experimental design, and the influence of formulation composition on the properties of the dispersions (CBZ heat of fusion and release rate) was estimated. Prepared solid dispersions were characterized using differential scanning calorimetry, attenuated total reflectance infrared spectroscopy and hot stage microscopy, as well as by determination of the dissolution rate of CBZ from the hot-melt extrudates. Solid dispersions of CBZ can be successfully prepared using the novel copolymer Soluplus. Inclusion of Poloxamer 407 as a plasticizer facilitated the processing and decreased the hardness of hot-melt extrudates. Regardless of their composition, all hot-melt extrudates displayed an improvement in the release rate compared to the pure CBZ, with formulations having the ratio of CBZ : Poloxamer 407 = 1 : 1 showing the highest increase in CBZ release rate. Interactions between the mixture components (CBZ and polymers), or quadratic effects of the components, play a significant role in overall influence on the CBZ release rate. © 2013 Royal Pharmaceutical Society.

Correlating the cold flow and melting properties of fatty acid methyl ester (FAME) mixtures

USDA-ARS?s Scientific Manuscript database

Fatty acid methyl ester (FAME) mixtures derived from plant oils or animal fats are used to make biodiesel, lubricants, surfactants, plasticizers, ink solvents, paint strippers and other products. Processing requires a precise knowledge of the physico-chemical properties of mixtures with diverse and ...

High temperature two component explosive

DOEpatents

Mars, James E.; Poole, Donald R.; Schmidt, Eckart W.; Wang, Charles

1981-01-01

A two component, high temperature, thermally stable explosive composition comprises a liquid or low melting oxidizer and a liquid or low melting organic fuel. The oxidizer and fuel in admixture are incapable of substantial spontaneous exothermic reaction at temperatures on the order of 475.degree. K. At temperatures on the order of 475.degree. K., the oxidizer and fuel in admixture have an activation energy of at least about 40 kcal/mol. As a result of the high activation energy, the preferred explosive compositions are nondetonable as solids at ambient temperature, and become detonable only when heated beyond the melting point. Preferable oxidizers are selected from alkali or alkaline earth metal nitrates, nitrites, perchlorates, and/or mixtures thereof. Preferred fuels are organic compounds having polar hydrophilic groups. The most preferred fuels are guanidinium nitrate, acetamide and mixtures of the two. Most preferred oxidizers are eutectic mixtures of lithium nitrate, potassium nitrate and sodium nitrate, of sodium nitrite, sodium nitrate and potassium nitrate, and of potassium nitrate, calcium nitrate and sodium nitrate.

A Binary Eutectic Mixture of TNAZ and R-Salt Explosives

NASA Astrophysics Data System (ADS)

Sandstrom, Mary; Manner, Virginia; Pemberton, Steven; Lloyd, Joseph; Tappan, Bryce

2011-06-01

TNAZ is a high performing explosive that is melt castable. However, the casting process can be problematic since TNAZ has a high vapor pressure exacerbated by a fairly high melting temperature. In order to mitigate the ill effects of its high vapor pressure, including a lower melting explosive was explored by making a series of mixtures of TNAZ and R-Salt. Initially, a eutectic temperature and composition was theoretically determined. Then a phase diagram was constructed from a series and mixtures by differential scanning calorimetery (DSC). The vapor pressure of the eutectic composition was determined by thermogravimetric analysis (TGA). Cylinder testing of the eutectic composition was carried out in copper tubes, 5'' long with 1/2 ``inner diameter and 1/16'' thick walls. The detonation velocity was measured using wire switches along the cylinder length and the expanding wall velocity was measured using PDV gauges. A rough evaluation of JWL equation-of-state parameters has been carried out. A more detailed evaluation is in progress.

Physical solid-state properties and dissolution of sustained-release matrices of polyvinylacetate.

PubMed

Gonzalez Novoa, Gelsys Ananay; Heinämäki, Jyrki; Mirza, Sabir; Antikainen, Osmo; Colarte, Antonio Iraizoz; Paz, Alberto Suzarte; Yliruusi, Jouko

2005-02-01

Solid-state compatibility and in vitro dissolution of direct-compressed sustained-release matrices of polyvinylacetate (PVAc) and polyvinylpyrrolidone (PVP) containing ibuprofen as a model drug were studied. Polyvinylalcohol (PVA) was used as an alternative water-soluble polymer to PVP. Differential scanning calorimetry (DSC) and powder X-ray diffractometry (PXRD) were used for characterizing solid-state polymer-polymer and drug-polymer interactions. The mechanical treatment for preparing physical mixtures of polyvinyl polymers and the drug (i.e. simple blending or stressed cogrinding) was shown not to affect the physical state of the drug and the polymers. With the drug-polymer mixtures the endothermic effect due to drug melting was always evident, but a considerable modification of the melting point of the drug in physical binary mixtures (drug:PVP) was observed, suggesting some interaction between the two. On the other hand, the lack of a significant shift of the melting endothermic peak of the drug in physical tertiary drug-polymer mixtures revealed no evidence of solid-state interaction between the drug and the present polymers. Sustained-release dissolution profiles were achieved from the direct-compressed matrices made from powder mixtures of the drug and PVAc combined with PVP, and the proportion of PVAc in the mixture clearly altered the drug release profiles in vitro. The drug release from the present matrix systems is controlled by both diffusion of the drug through the hydrate matrix and the erosion of the matrix itself.

Formation of Aluminum Particles with Shell Morphology during Pressureless Spark Plasma Sintering of Fe–Al Mixtures: Current-Related or Kirkendall Effect?

PubMed Central

Dudina, Dina V.; Bokhonov, Boris B.; Mukherjee, Amiya K.

2016-01-01

A need to deeper understand the influence of electric current on the structure and properties of metallic materials consolidated by Spark Plasma Sintering (SPS) stimulates research on inter-particle interactions, bonding and necking processes in low-pressure or pressureless conditions as favoring technique-specific local effects when electric current passes through the underdeveloped inter-particle contacts. Until now, inter-particle interactions during pressureless SPS have been studied mainly for particles of the same material. In this work, we focused on the interactions between particles of dissimilar materials in mixtures of micrometer-sized Fe and Al powders forming porous compacts during pressureless SPS at 500–650 °C. Due to the chemical interaction between Al and Fe, necks of conventional shape did not form between the dissimilar particles. At the early interaction stages, the Al particles acquired shell morphology. It was shown that this morphology change was not related to the influence of electric current but was due to the Kirkendall effect in the Fe–Al system and particle rearrangement in a porous compact. No experimental evidence of melting or melt ejection during pressureless SPS of the Fe–Al mixtures or Fe and Al powders sintered separately was observed. Porous FeAl-based compacts could be obtained from Fe-40at.%Al mixtures by pressureless SPS at 650 °C. PMID:28773498

Application of simplex-centroid mixture design to optimize stabilizer combinations for ice cream manufacture.

PubMed

BahramParvar, Maryam; Tehrani, Mostafa Mazaheri; Razavi, Seyed M A; Koocheki, Arash

2015-03-01

This study aimed to obtain the optimum formulation for stabilizers in ice cream that could contest with blends presented nowadays. Thus, different mixtures of three stabilizers, i.e. basil seed gum, carboxymethyl cellulose, and guar gum, at two concentrations (0.15 % & 0.35 %) were studied using mixture design methodology. The influence of these mixtures on some properties of ice cream and the regression models for them were also determined. Generally, high ratios of basil seed gum in mixture developed the apparent viscosity of ice cream mixes and decreased the melting rate. Increasing proportion of this stabilizer as well as guar gum in the mixtures at concentration of 0.15 % enhanced the overrun of samples. Based on the optimization criteria, the most excellent combination was 84.43 % basil seed gum and 15.57 % guar gum at concentration of 0.15 %. This research proved the capability of basil seed gum as a novel stabilizer in ice cream stabilization.

Various Particulate Matter Effects on Glacial Melting Rates in the Himalayan Mountain Range

NASA Astrophysics Data System (ADS)

Barwegen, S.

2017-12-01

Due to increased human activity and the impact of global warming in the Himalayas, glaciers are melting at alarming rates. It is hypothesized that by the year 2100, about 5,500 glaciers located in the Hindu-Kush will melt by up to 70%-90%. This will be severely detrimental to farmers as well as lessen the potential to harness hydropower, which requires the glaciers to be fully present (Vidal 2015). The melting of these glaciers is accelerating, in part, due to the deposition of particulate matter onto the snow, which lowers the albedo and causes the glaciers to absorb more heat. The Himalayan glaciers, specifically, are melting due to intense human movement over the snow, movement of particulate matter from storms, the increase in temperatures due to global warming, and soot deposited from forest fires (Dimmick 2014). This whole mountain range needs to retain glaciers in order to support the population of people living there by providing water. This project investigated the effect of both different types and amounts of particulate matter (PM) on ice melting rates. It was a model simulating the impact of PM of varying sizes and sources on glacial melting rates in the Himalayan glaciers. The impact of eight different types of PM (charcoal, pumice, sand/organic soil mixture, peat moss/soil, gravel/soil, soot, and soil), at two different masses (0.1g and 0.3g) on the melting rate of ice was assessed. Ice cubes were covered in PM and placed 5 cm away from a 50W incandescent bulb, with mass measured at regular intervals as they melted. Mass loss was recorded at 3, 6, 9, and 15 minutes and each sample type was repeated in triplicate. Over the course of the experiment, the ice cubes with 0.1 gram of PM were observed to be melting at a slower rate. Of the ice cubes with .3 g of PM on top, the ice covered in the sand and organic soil mixture had the lowest mass loss (3.4 g over 15 minutes), while the gravel and potting soil (4.9 g over 15 minutes) resulted in the highest (4.2 g/15 min.). This trend was different with the ice cubes covered in less PM (.1 g). Of these, the gravel/potting soil mixture showed the highest mass loss (4.14 g/15 min.), while the gravel and potting soil mixture showed the lowest at 2.4g/15min. The results of this study help quantify the impact of particulate matter characteristics such as size and amount on the glacial melting rates in the Himalayas.

Purification of tantalum by plasma arc melting

DOEpatents

Dunn, Paul S.; Korzekwa, Deniece R.

1999-01-01

Purification of tantalum by plasma arc melting. The level of oxygen and carbon impurities in tantalum was reduced by plasma arc melting the tantalum using a flowing plasma gas generated from a gas mixture of helium and hydrogen. The flowing plasma gases of the present invention were found to be superior to other known flowing plasma gases used for this purpose.

Nondestructive method for chemically machining crucibles or molds from their enclosed ingots and castings

DOEpatents

Stout, Norman D.; Newkirk, Herbert W.

1991-01-01

An inventive method is described for chemically machining rhenium, rhenium and tungsten alloy, and group 5b and 6b crucibles or molds from included ingots and castings comprised of oxide crystals including YAG and YAG based crystals, garnets, corundum crystals, and ceramic oxides. A mixture of potassium hydroxide and 15 to 90 weight percent of potassium nitrate is prepared and maintained at a temperature above melting and below the lower of 500 degrees centigrade or the temperature of decomposition of the mixture. The enveloping metal container together with its included oxide crystal object is rotated within the heated KOH-KNO.sub.3 mixture, until the container is safely chemically machined away from the included oxide crystal object.

Thermal behaviour of procaine and benzocaine Part II: compatibility study with some pharmaceutical excipients used in solid dosage forms

PubMed Central

2013-01-01

Background The compatibility study of active substances with excipients finds an important role in the domain of pharmaceutical research, being known the fact that final formulation is the one administered to the patient. In order to evaluate the compatibility between active substance and excipients, different analytical techniques can be used, based on their accuracy, reproducibility and fastness. Results Compatibility study of two well-known active substances, procaine and benzocaine, with four commonly used excipients, was carried out employing thermal analysis (TG/DTG/HF) and Fourier Transform Infrared Spectroscopy (UATR-FT-IR). The selected excipients were microcrystalline cellulose, lactose monohydrate, magnesium stearate and talc. Equal proportion of active substance and excipients (w/w) was utilized in the interaction study. The absolute value of the difference between the melting point peak of active substances and the one corresponding for the active substances in the analysed mixture, as well the absolute value of the difference between the enthalpy of the pure active ingredient melting peak and that of its melting peak in the different analysed mixtures were chosen as indexes of the drug-excipient interaction degree. All the results obtained through thermal analysis were also sustained by FT-IR spectroscopy. Conclusions The corroboration of data obtained by thermal analysis with the ones from FT-IR spectroscopy indicated that no interaction occurs between procaine and benzocaine, with microcrystalline cellulose and talc, as well for the benzocaine-lactose mixture. Interactions were confirmed between procaine and benzocaine respectively and magnesium stearate, and for procaine and lactose. PMID:23962059

Pyrochemical recovery of plutonium from calcium fluoride reduction slag

DOEpatents

Christensen, D.C.

A pyrochemical method of recovering finely dispersed plutonium metal from calcium fluoride reduction slag is claimed. The plutonium-bearing slag is crushed and melted in the presence of at least an equimolar amount of calcium chloride and a few percent metallic calcium. The calcium chloride reduces the melting point and thereby decreases the viscosity of the molten mixture. The calcium reduces any oxidized plutonium in the mixture and also causes the dispersed plutonium metal to coalesce and settle out as a separate metallic phase at the bottom of the reaction vessel. Upon cooling the mixture to room temperature, the solid plutonium can be cleanly separated from the overlying solid slag, with an average recovery yield on the order of 96 percent.

Structure and effective interactions in three-component hard sphere liquids.

PubMed

König, A; Ashcroft, N W

2001-04-01

Complete and simple analytical expressions for the partial structure factors of the ternary hard sphere mixture are obtained within the Percus-Yevick approximation and presented as functions of relative packing fractions and relative hard sphere diameters. These solutions follow from the Laplace transform method as applied to multicomponent systems by Lebowitz [Phys. Rev. 133, A895 (1964)]. As an important application, we examine effective interactions in hard sphere liquid mixtures using the microscopic information contained in their partial structure factors. Thus the ensuring pair potential for an effective one-component system is obtained from the correlation functions by using an approximate inversion, and examples of effective potentials for three-component hard sphere mixtures are given. These mixtures may be of particular interest for the study of the packing aspects of melts that form glasses or quasicrystals, since noncrystalline solids often emerge from melts with at least three atomic constituents.

Taste Masking of Griseofulvin and Caffeine Anhydrous Using Kleptose Linecaps DE17 by Hot Melt Extrusion.

PubMed

Juluri, Abhishek; Popescu, Carmen; Zhou, Leon; Murthy, Reena N; Gowda, Vanaja K; Chetan Kumar, P; Pimparade, Manjeet B; Repka, Michael A; Murthy, S Narasimha

2016-02-01

The objective of this project was to investigate the potential of Kleptose Linecaps DE17 (KLD) in masking the unpleasant/bitter taste of therapeutic agents by hot melt extrusion (HME). Griseofulvin (GRI) and caffeine anhydrous (CA) were used as a bitter active pharmaceutical ingredient (API) model drugs. Thermogravimetric studies confirmed the stability of GRI, CA, and KLD at the employed extrusion temperatures. The differential scanning calorimetry (DSC) studies revealed a characteristic melting endotherm of GRI at 218-220°C and CA at 230-232°C in the physical mixtures as well as in all extrudates over the period of study, indicating the crystalline nature of drug. HME of KLD was achieved only in the presence of plasticizer. Among the several plasticizers investigated, xylitol showed improved processability of KLD at 15% w/w concentration. Dissolution studies of HME extrudates using simulated salivary medium exhibited ∼threefold less release compared to physical mixture at the end of 5 min (the lesser drug release, better the taste masking efficiency). Furthermore, the results from the sensory evaluation of products in human panel demonstrated strong bitter taste in the case of physical mixture compared to the HME formulation, suggesting the potential of Kleptose Linecaps DE17 as taste masking polymer in melt extruded form.

Universal digital high-resolution melt: a novel approach to broad-based profiling of heterogeneous biological samples.

PubMed

Fraley, Stephanie I; Hardick, Justin; Masek, Billie J; Jo Masek, Billie; Athamanolap, Pornpat; Rothman, Richard E; Gaydos, Charlotte A; Carroll, Karen C; Wakefield, Teresa; Wang, Tza-Huei; Yang, Samuel

2013-10-01

Comprehensive profiling of nucleic acids in genetically heterogeneous samples is important for clinical and basic research applications. Universal digital high-resolution melt (U-dHRM) is a new approach to broad-based PCR diagnostics and profiling technologies that can overcome issues of poor sensitivity due to contaminating nucleic acids and poor specificity due to primer or probe hybridization inaccuracies for single nucleotide variations. The U-dHRM approach uses broad-based primers or ligated adapter sequences to universally amplify all nucleic acid molecules in a heterogeneous sample, which have been partitioned, as in digital PCR. Extensive assay optimization enables direct sequence identification by algorithm-based matching of melt curve shape and Tm to a database of known sequence-specific melt curves. We show that single-molecule detection and single nucleotide sensitivity is possible. The feasibility and utility of U-dHRM is demonstrated through detection of bacteria associated with polymicrobial blood infection and microRNAs (miRNAs) associated with host response to infection. U-dHRM using broad-based 16S rRNA gene primers demonstrates universal single cell detection of bacterial pathogens, even in the presence of larger amounts of contaminating bacteria; U-dHRM using universally adapted Lethal-7 miRNAs in a heterogeneous mixture showcases the single copy sensitivity and single nucleotide specificity of this approach.

Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm

NASA Astrophysics Data System (ADS)

Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

Modelling melting in crustal environments, with links to natural systems in the Nepal Himalayas

NASA Astrophysics Data System (ADS)

Isherwood, C.; Holland, T.; Bickle, M.; Harris, N.

2003-04-01

Melt bodies of broadly granitic character occur frequently in mountain belts such as the Himalayan chain which exposes leucogranitic intrusions along its entire length (e.g. Le Fort, 1975). The genesis and disposition of these bodies have considerable implications for the development of tectonic evolution models for such mountain belts. However, melting processes and melt migration behaviour are influenced by many factors (Hess, 1995; Wolf &McMillan, 1995) which are as yet poorly understood. Recent improvements in internally consistent thermodynamic datasets have allowed the modelling of simple granitic melt systems (Holland &Powell, 2001) at pressures below 10 kbar, of which Himalayan leucogranites provide a good natural example. Model calculations such as these have been extended to include an asymmetrical melt-mixing model based on the Van Laar approach, which uses volumes (or pseudovolumes) for the different end-members in a mixture to control the asymmetry of non-ideal mixing. This asymmetrical formalism has been used in conjunction with several different entropy of mixing assumptions in an attempt to find the closest fit to available experimental data for melting in simple binary and ternary haplogranite systems. The extracted mixing data are extended to more complex systems and allow the construction of phase relations in NKASH necessary to model simple haplogranitic melts involving albite, K-feldspar, quartz, sillimanite and {H}2{O}. The models have been applied to real bulk composition data from Himalayan leucogranites.

High-Performance Polymers Having Low Melt Viscosities

NASA Technical Reports Server (NTRS)

Jensen, Brian J.

2005-01-01

High-performance polymers that have improved processing characteristics, and a method of making them, have been invented. One of the improved characteristics is low (relative to corresponding prior polymers) melt viscosities at given temperatures. This characteristic makes it possible to utilize such processes as resin-transfer molding and resin-film infusion and to perform autoclave processing at lower temperatures and/or pressures. Another improved characteristic is larger processing windows that is, longer times at low viscosities. Other improved characteristics include increased solubility of uncured polymer precursors that contain reactive groups, greater densities of cross-links in cured polymers, improved mechanical properties of the cured polymers, and greater resistance of the cured polymers to chemical attack. The invention is particularly applicable to poly(arylene ether)s [PAEs] and polyimides [PIs] that are useful as adhesives, matrices of composite materials, moldings, films, and coatings. PAEs and PIs synthesized according to the invention comprise mixtures of branched, linear, and star-shaped molecules. The monomers of these polymers can be capped with either reactive end groups to obtain thermosets or nonreactive end groups to obtain thermoplastics. The synthesis of a polymeric mixture according to the invention involves the use of a small amount of a trifunctional monomer. In the case of a PAE, the trifunctional monomer is a trihydroxy- containing compound for example, 1,3,5-trihydroxybenzene (THB). In the case of a PI, the trifunctional monomer is a triamine for example, triamino pyrimidine or melamine. In addition to the aforementioned trifunctional monomer, one uses the difunctional monomers of the conventional formulation of the polymer in question (see figure). In cases of nonreactive end caps, the polymeric mixtures of the invention have melt viscosities and melting temperatures lower than those of the corresponding linear polymers of equal molecular weights. The lower melting temperatures and melt viscosities provide larger processing windows. In cases of reactive end caps, the polymeric mixtures of the invention have lower melt viscosities before curing and the higher cross-link densities after curing (where branching in the uncured systems would become cross-links in the cured systems), relative to the corresponding linear polymers of equal molecular weights. The greater cross-link densities afford increased resistance to chemical attack and improved mechanical properties.

Thermal phase diagram of acetamide-benzoic acid and benzoic acid-phthalimide binary systems for solar thermal applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Rohitash, E-mail: dootrohit1976@gmail.com; Department of Physics & Center for Solar Energy, Indian Institute of Technology Jodhpur, Rajasthan, India 342011, +91-291-2449045; Kumar, Ravindra

2016-05-06

Thermal properties of Acetamide (AM) – Benzoic acid (BA) and Benzoic acid (BA) – Phthalimide (PM) binary eutectic systems are theoretically calculated using thermodynamic principles. We found that the binary systems of AM-BA at 67.6 : 32.4 molar ratio, BA-PM at 89.7 : 10.3 molar ratio form eutectic mixtures with melting temperatures ~ 54.5 °C and 114.3 °C respectively. Calculated latent heat of fusion for these eutectic mixtures are 191 kJ/kg and 146.5 kJ/kg respectively. These melting temperatures and heat of fusions of these eutectic mixtures make them suitable for thermal energy storage applications in solar water heating and solarmore » cooking systems.« less

An experimental method for directly determining the interconnectivity of melt in a partially molten system

NASA Technical Reports Server (NTRS)

Daines, Martha J.; Richter, Frank M.

1988-01-01

An experimental method for directly determining the degree of interconnectivity of melt in a partially molten system is discussed using an olivine-basalt system as an example. Samarium 151 is allowed time to diffuse through mixtures of olivine and basalt powder which have texturally equilibrated at 1350 C and 13 to 15 kbars. The final distribution of samarium is determined through examination of developed radiographs of the samples. Results suggest an interconnected melt network is established at melt fractions at least as low as 1 wt pct and all melt is completely interconnected at melt fractions at least as low as 2 wt pct for the system examined.

Molecular dynamics study of congruent melting of the equimolar ionic liquid-benzene inclusion crystal [emim][NTf2]•C6H6

NASA Astrophysics Data System (ADS)

Kowsari, M. H.; Alavi, Saman; Ashrafizaadeh, Mahmud; Najafi, Bijan

2010-01-01

We use molecular dynamics simulations to study the structure, dynamics, and details of the mechanism of congruent melting of the equimolar mixture of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide with benzene, [emim][NTf2]•C6H6. Changes in the molecular arrangement, radial distribution functions, and the dynamic behavior of species are used to detect the solid to liquid transition, show an indication of the formation of polar islands by aggregating of the ions in the liquid phase, and characterize the melting process. The predicted enthalpy of melting ΔHm=38±2 kJ mol-1 for the equimolar inclusion mixture at 290 K is in good agreement with the differential scanning calorimetry experimental results of 42±2 kJ mol-1. The dynamics of the ions and benzene molecules were studied in the solid and liquid states by calculating the mean-square displacement (MSD) and the orientational autocorrelation function. The MSD plots show strong association between ion pairs of the ionic liquid in the inclusion mixture. Indeed, the presence of a stoichiometric number of benzene molecules does not affect the nearest neighbor ionic association between [emim]+ and [NTf2]-, but increases the MSDs of both cations and anions compared to pure liquid [emim][NTf2], showing that second shell ionic associations are weakened. We monitored the rotational motion of the alkyl chain sides of imidazolium cations and also calculated the activation energy for rotation of benzene molecules about their C6 symmetry axes in their lattice sites prior to melting.

Comparison of water gel desserts from fish skin and pork gelatins using instrumental measurements.

PubMed

Zhou, Peng; Regenstein, Joe M

2007-05-01

The objective of this study was to compare water gel desserts from various gelatins using instrumental measurements. The puncture test and texture profile analysis (TPA) with compression were determined at 25% and 75% deformation; the melting properties were determined rheologically by monitoring the change of storage modulus (G') with increasing temperature. The measurements with 25% deformation were always nondestructive, while measurements with 75% deformation were mostly destructive. Desserts made from Alaska pollock gelatin (AG) or gelatin mixtures containing AG were more resistant to the destruction caused by the large deformation than tilapia gelatin and pork gelatins. In addition, the gel dessert made from AG melted at a lower temperature than those from tilapia skin gelatin and pork gelatins, while desserts made from gelatin mixtures reflected the melting properties of the separate gelatins.

Estimated heats of fusion of fluoride salt mixtures suitable for thermal energy storage applications

NASA Technical Reports Server (NTRS)

Misra, A. K.; Whittenberger, J. D.

1986-01-01

The heats of fusion of several fluoride salt mixtures with melting points greater than 973 K were estimated from a coupled analysis of the available thermodynamic data and phase diagrams. Simple binary eutectic systems with and without terminal solid solutions, binary eutectics with congruent melting intermediate phases, and ternary eutectic systems were considered. Several combinations of salts were identified, most notable the eutectics LiF-22CaF2 and NaF-60MgF2 which melt at 1039 and 1273 K respectively which posses relatively high heats of fusion/gm (greater than 0.7 kJ/g). Such systems would seemingly be ideal candidates for the light weight, high energy storage media required by the thermal energy storage unit in advanced solar dynamic power systems envisioned for the future space missions.

Melt dispersion granules: formulation and evaluation to improve oral delivery of poorly soluble drugs - a case study with valsartan.

PubMed

Chella, Naveen; Tadikonda, Ramarao

2015-06-01

Solid dispersion (SD) technique is a promising strategy to improve the solubility and dissolution of BCS class II drugs. However, only few products are marketed till today based on SD technology due to poor flow properties and stability. The present work was intended to solve these problems by using combination approach, melt dispersion and surface adsorption technologies. The main aim of the present work is to improve the absorption in the stomach (at lower pH) where the absorption window exists for the drug by improving the dissolution, resulting in the enhancement of oral bioavailability of poorly soluble, weakly acidic drug with pH dependant solubility, i.e. valsartan. Melt dispersion granules were prepared in different ratios using different carriers (Gelucire 50/13, PEG 8000 and Pluronic F-68) and lactose as an adsorbent. Similarly, physical mixtures were also prepared at corresponding ratios. The prepared dispersion granules and physical mixtures were characterized by FTIR, DSC and in vitro dissolution studies. DSC studies revealed reduction in the crystallinity with a possibility of presence of amorphous character of drug in the dispersion granules. From dissolution studies, valsartan Gelucire dispersion (GSD4; 1:4 ratio) showed complete drug release in 30 min against the plain drug which showed only 11.31% of drug release in 30 min. Pharmacokinetic studies of optimized formulation in male Wistar rats showed 2.65-fold higher bioavailability and 1.47-fold higher Cmax compared to pure drug. The melt dispersion technology has the potential to improve dissolution and the bioavailability of BCS class II drugs.

2D Models for the evolving distribution of impact melt at the lunar near-surface

NASA Astrophysics Data System (ADS)

Liu, T.; Michael, G. G.; Oberst, J.

2017-09-01

This study aims to investigate the cumulative effect of the impact gardening process. The lateral distribution of the melt with diverse ages is traced in this model. Using the observed distribution of melt age in lunar samples and meteorites, the possible scenarios of the lunar impact history can be discriminated. The record is also helpful for the future lunar sampling, guiding the choice of site to obtain samples from different impact basins, and to understand the mixture of melt ages observed at any one site.

Sensor Detects Overheating Of Perishable Material

NASA Technical Reports Server (NTRS)

Dordick, Jonathan S.; Klibanov, Alexander

1990-01-01

Experimental temperature sensor changes color rapidly and irreversibly when temperature rises above pre-determined level. Based on reactions of enzymes in paraffins, blended so mixture melts at temperature considered maximum safe value. Similar devices used to detect temperature abuse, whether foods or medicines refrigerated exposed to excessive temperatures during shipment and storage. By viewing sensor, receiving clerk tells immediately whether product maintained at safe temperatures and acceptable.

The Use of Citetaal among Adolescents in Limburg: The Role of Space Appropriation in Language Variation and Change

ERIC Educational Resources Information Center

Marzo, Stefania; Ceuleers, Evy

2011-01-01

The term "Citetaal" was originally used to refer to the language spoken by Italian immigrants in the Eastern part of Flanders (Limburg) and diffused in the former ghettoised mining areas (the cite). It is a melting pot language, based on Dutch but with a high amount of code mixture from immigrant languages, mostly Italian and Turkish.…

Effect of Melting Point on the Physical Properties of Anhydrous Milk Fat

NASA Astrophysics Data System (ADS)

Wang, Yunna; Li, Yang; Han, Jie; Li, Yan; Zhang, Liebing

2017-12-01

The effect of melting point on the physical properties of anhydrous milk fat were investigated. The results showed that high melting fractions (HMF) (S30,S35) were enriched in long-chain fatty acids, whereas low melting fractions (LMF)(S5,S10,S15) were enriched in short-chain and unsaturated fatty acids. From S5 to S35, enthalpy value was gradually increased on both crystallization and melting condition, so as SFC on different temperature. The mixture and chemical interesterification allowed obtaining fats with various degrees of plasticity, increasing the possibilities for the commercial use of different fraction of AMF.

High electrical resistivity Nd-Fe-B die-upset magnet doped with eutectic DyF3-LiF salt mixture

NASA Astrophysics Data System (ADS)

Kim, K. M.; Kim, J. Y.; Kwon, H. W.; Kim, D. H.; Lee, J. G.; Yu, J. H.

2017-05-01

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 μ Ω .cm compared to 190 μ Ω .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.

Boundary pressure of inter-connection of Fe-Ni-S melt in olivine based on in-situ X-ray tomography: Implication to core formation in asteroids

NASA Astrophysics Data System (ADS)

Terasaki, H.; Urakawa, S.; Uesugi, K.; Nakatsuka, A.; Funakoshi, K.; Ohtani, E.

2011-12-01

Interconnectivity of Fe-alloy melt in crystalline silicates is important property for the core formation mechanism in planetary interior. In previous studies, the interconnectivity of Fe-alloy melt has been studied based on textural observation of recovered samples from high pressure and temperature. However, there is no observation under high pressure and temperature. We have developed 80-ton uni-axial press for X-ray computed micro-tomography (X-CT) and performed X-CT measurement under high pressure (Urakawa et al. 2010). Here we report X-CT measurement of Fe-Ni-S melt in crystalline olivine and interconnectivity of the melt up to 3.5 GPa and 1273 K. X-CT measurements were carried out at BL20B2 beamline, SPring-8 synchrotron facility. The sample was powder mixture of Fe-Ni-S and olivine, which was enclosed in graphite capsule. Heating was performed using a cylindrical graphite furnace. Pressure was generated using opposed toroidal-shape WC anvil. The uni-axial press was set on the rotational stage and X-ray radiography image of the sample was collected using CCD camera from 0°to 180°with 0.3° step. 3-D image of the sample was obtained by reconstructing the 2-D radiography image. The 3-D CT image shows that the size of the Fe-Ni-S melt increased significantly compared to that before melting below 2.5 GPa, suggesting that the melt was interconnected in olivine crystals. On the other hand, 3-D texture of the sample at 3.5 GPa did not show difference from that before melting. Therefore, the boundary of inter-connection of Fe-Ni-S melt is likely to locate between 2.5 and 3.5 GPa. This result is important application for the core formation mechanism especially in small bodies, such as differentiated asteroids.

Rheological Characterization of Molten Polymer-Drug Dispersions as a Predictive Tool for Pharmaceutical Hot-Melt Extrusion Processability.

PubMed

Van Renterghem, Jeroen; Vervaet, Chris; De Beer, Thomas

2017-11-01

The aim of this study was to investigate (i) the influence of drug solid-state (crystalline or dissolved in the polymer matrix) on the melt viscosity and (ii) the influence of the drug concentration, temperature and shear rate on polymer crystallization using rheological tests. Poly (ethylene oxide) (PEO) (100.000 g/mol) and physical mixtures (PM) containing 10-20-30-40% (w/w) ketoprofen or 10% (w/w) theophylline in PEO were rheologically characterized. Rheological tests were performed (frequency and temperature sweeps in oscillatory shear as well as shear-induced crystallization experiments) to obtain a thorough understanding of the flow behaviour and crystallization of PEO-drug dispersions. Theophylline did not dissolve in PEO as the complex viscosity (η*) of the drug-polymer mixture increased as compared to that of neat PEO. In contrast, ketoprofen dissolved in PEO and acted as a plasticizer, decreasing η*. Acting as a nucleating agent, theophylline induced the crystallization of PEO upon cooling from the melt. On the other hand, ketoprofen inhibited crystallization upon cooling. Moreover, higher concentrations of ketoprofen in the drug-polymer mixture increasingly inhibited polymer crystallization. However, shear-induced crystallization was observed for all tested mixtures containing ketoprofen. The obtained rheological results are relevant for understanding and predicting HME processability (e.g., barrel temperature selection) and downstream processing such as injection moulding (e.g., mold temperature selection).

An assessment of the CORCON-MOD3 code. Part 1: Thermal-hydraulic calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Strizhov, V.; Kanukova, V.; Vinogradova, T.

1996-09-01

This report deals with the subject of CORCON-Mod3 code validation (thermal-hydraulic modeling capability only) based on MCCI (molten core concrete interaction) experiments conducted under different programs in the past decade. Thermal-hydraulic calculations (i.e., concrete ablation, melt temperature, melt energy, concrete temperature, and condensible and non-condensible gas generation) were performed with the code, and compared with the data from 15 experiments, conducted at different scales using both simulant (metallic and oxidic) and prototypic melt materials, using different concrete types, and with and without an overlying water pool. Sensitivity studies were performed in a few cases involving, for example, heat transfer frommore » melt to concrete, condensed phase chemistry, etc. Further, special analysis was performed using the ACE L8 experimental data to illustrate the differences between the experimental and the reactor conditions, and to demonstrate that with proper corrections made to the code, the calculated results were in better agreement with the experimental data. Generally, in the case of dry cavity and metallic melts, CORCON-Mod3 thermal-hydraulic calculations were in good agreement with the test data. For oxidic melts in a dry cavity, uncertainties in heat transfer models played an important role for two melt configurations--a stratified geometry with segregated metal and oxide layers, and a heterogeneous mixture. Some discrepancies in the gas release data were noted in a few cases.« less

Reduced sediment melting at 7.5-12 GPa: phase relations, geochemical signals and diamond nucleation

NASA Astrophysics Data System (ADS)

Brey, G. P.; Girnis, A. V.; Bulatov, V. K.; Höfer, H. E.; Gerdes, A.; Woodland, A. B.

2015-08-01

Melting of carbonated sediment in the presence of graphite or diamond was experimentally investigated at 7.5-12 GPa and 800-1600 °C in a multianvil apparatus. Two starting materials similar to GLOSS of Plank and Langmuir (Chem Geol 145:325-394, 1998) were prepared from oxides, carbonates, hydroxides and graphite. One mixture (Na-gloss) was identical in major element composition to GLOSS, and the other was poorer in Na and richer in K (K-gloss). Both starting mixtures contained ~6 wt% CO2 and 7 wt% H2O and were doped at a ~100 ppm level with a number of trace elements, including REE, LILE and HFSE. The near-solidus mineral assemblage contained a silica polymorph (coesite or stishovite), garnet, kyanite, clinopyroxene, carbonates (aragonite and magnesite-siderite solid solution), zircon, rutile, bearthite and hydrous phases (phengite and lawsonite at <9 GPa and the hydrous aluminosilicates topaz-OH and phase egg at >10 GPa). Hydrous phases disappear at ~900 °C, and carbonates persist up to 1000-1100 °C. At temperatures >1200 °C, the mineral assemblage consists of coesite or stishovite, kyanite and garnet. Clinopyroxene stability depends strongly on the Na content in the starting mixture; it remains in the Na-gloss composition up to 1600 °C at 12 GPa, but was not observed in K-gloss experiments above 1200 °C. The composition of melt or fluid changes gradually with increasing temperature from hydrous carbonate-rich (<10 wt% SiO2) at 800-1000 °C to volatile-rich silicate liquids (up to 40 wt% SiO2) at high temperatures. Trace elements were analyzed in melts and crystalline phases by LA ICP MS. The garnet-melt and clinopyroxene-melt partition coefficients are in general consistent with results from the literature for volatile-free systems and silicocarbonate melts derived by melting carbonated peridotites. Most trace elements are strongly incompatible in kyanite and silica polymorphs ( D < 0.01), except for V, Cr and Ni, which are slightly compatible in kyanite ( D > 1). Aragonite and Fe-Mg carbonate have very different REE partition coefficients ( D Mst-Sd/L ~ 0.01 and D Arg/L ~ 1). Nb, Ta, Zr and Hf are strongly incompatible in both carbonates. The bearthite/melt partition coefficients are very high for LREE (>10) and decrease to ~1 for HREE. All HFSE are strongly incompatible in bearthite. In contrast, Ta, Nb, Zr and Hf are moderately to strongly compatible in ZrSiO4 and TiO2 phases. Based on the obtained partition coefficients, the composition of a mobile phase derived by sediment melting in deep subduction zones was calculated. This phase is strongly enriched in incompatible elements and displays a pronounced negative Ta-Nb anomaly but no Zr-Hf anomaly. Although all experiments were conducted in the diamond stability field, only graphite was observed in low-temperature experiments. Spontaneous diamond nucleation and the complete transformation of graphite to diamond were observed at temperatures above 1200-1300 °C. We speculate that the observed character of graphite-diamond transformation is controlled by relationships between the kinetics of metastable graphite dissolution and diamond nucleation in a hydrous silicocarbonate melt that is oversaturated in C.

Phase transition and chemical decomposition of hydrogen peroxide and its water mixtures under high pressures.

PubMed

Chen, Jing-Yin; Kim, Minseob; Yoo, Choong-Shik; Dattelbaum, Dana M; Sheffield, Stephen

2010-06-07

We have studied the pressure-induced phase transition and chemical decomposition of hydrogen peroxide and its mixtures with water to 50 GPa, using confocal micro-Raman and synchrotron x-ray diffractions. The x-ray results indicate that pure hydrogen peroxide crystallizes into a tetragonal structure (P4(1)2(1)2), the same structure previously found in 82.7% H(2)O(2) at high pressures and in pure H(2)O(2) at low temperatures. The tetragonal phase (H(2)O(2)-I) is stable to 15 GPa, above which transforms into an orthorhombic structure (H(2)O(2)-II) over a relatively large pressure range between 13 and 18 GPa. Inferring from the splitting of the nu(s)(O-O) stretching mode, the phase I-to-II transition pressure decreases in diluted H(2)O(2) to around 7 GPa for the 41.7% H(2)O(2) and 3 GPa for the 9.5%. Above 18 GPa H(2)O(2)-II gradually decomposes to a mixture of H(2)O and O(2), which completes at around 40 GPa for pure and 45 GPa for the 9.5% H(2)O(2). Upon pressure unloading, H(2)O(2) also decomposes to H(2)O and O(2) mixtures across the melts, occurring at 2.5 GPa for pure and 1.5 GPa for the 9.5% mixture. At H(2)O(2) concentrations below 20%, decomposed mixtures form oxygen hydrate clathrates at around 0.8 GPa--just after H(2)O melts. The compression data of pure H(2)O(2) and the stability data of the mixtures seem to indicate that the high-pressure decomposition is likely due to the pressure-induced densification, whereas the low-pressure decomposition is related to the heterogeneous nucleation process associated with H(2)O(2) melting.

Effects of Microsecond Pulse Laser Irradiation on Vis-NIR Reflectance Spectrum of Carbonaceous Chondrite Simulant: Implications for Martian Moons and Primitive Asteroids

NASA Technical Reports Server (NTRS)

Hiroi, T.; Moroz, L. V.; Shingareva, T. V.; Basilevsky, A. T.; Pieters, M.

2003-01-01

Goal of this study is to make a progress in understanding the optical effects of space weathering on small bodies believed to be similar in composition to carbonaceous chondrites: C, G, B, F, T, D, and P asteroids and possibly Martian satellites Phobos and Deimos. The companion work focuses on petrological and mineralogical aspects of this process. One of the main factors of space weathering is meteorite and micrometeorite bombardment leading, in particular, to impact melting of components of the regolith. Studies of lunar regolith and laboratory experiments simulating impact melting show that the melting products differ from the unmelted material in mineralogy and distribution of chemical components among different phases that results in spectral changes. We simulate impact melting of CM chondrite by pulse laser irradiation of an artificial analog of such a meteorite. The analog is a mixture of 46 wt.% non-magnetic fraction of L5 ordinary chondrite Tsarev, 47 wt.% serpentine, 5 wt.% kerite, and 2 wt.% calcite. It simulates rather well bulk chemistry, including volatiles such as H2O and CO2, and only approximately the CM chondrite mineralogy. Thus, we do not expect the mixture to be spectrally similar to CM chondrites, but expect the laser melting products to be similar to those formed by impact melting of natural CM chondrites.

A Comparative Study of the Corrosion Behavior of Three Stainless Steels in an Eutectic (Li,Na,K)2CO3 Melt with and without (Na,K)Cl Additives at 973K in Air

NASA Astrophysics Data System (ADS)

Zeng, C. L.; Liu, Y.

2011-04-01

The ternary carbonate eutectic mixture of Li2CO3, K2CO3 and Na2CO3 as a heat transfer and storage medium has excellent thermophysical properties, but with high viscidity as compared with some other inorganic salts such as chlorides and nitrates. The addition of chlorides or fluorides to molten carbonates may improve their fluidity, but possibly making the melt become more corrosive. In this study, the corrosion behavior of type 304, 310 and 316 stainless steels in an eutectic (Li,Na,K)2CO3 melt with and without an eutectic mixture of NaCl and KCl at 973K in air have been examined. The experimental results indicated that 310 steel shows a much better corrosion resistance in molten carbonates than both 304 and 316 steels, due to the formation of a continuous LiCrO2 scale. The addition of chlorides to carbonates melt accelerated the corrosion of the steels, especially 310 steel, producing scales with more porosity.

The effect of phase change materials on the frontal polymerization of a triacrylate

NASA Astrophysics Data System (ADS)

Viner, Veronika G.; Pojman, John A.; Golovaty, Dmitry

2010-06-01

The production of smoke and fumes is a major obstacle to the practical use of thermal frontal polymerization. The front temperature and the amount of smoking can be reduced by adding inert fillers, such as clay and silica, to the reactive mixture. Here we investigate the possibility of incorporating inert materials that melt (so-called phase change materials) to the mixture. By performing both experiments and mathematical modeling, we demonstrate that, in addition to the standard parameters of frontal polymerization, the front temperature and velocity depend on the melting point and heat of fusion of the phase change material. We use the method of matched asymptotic expansions to develop an explicit expression for the velocity of the reaction front. The expression demonstrates that the behavior of the front is determined by the difference between the reaction temperature and the melting temperature, with the front being slower and cooler if melting occurs farther ahead of the reaction front. The theoretical trends are hard to confirm directly because different characteristics of the phase change material cannot be varied separately.

Transport Properties of Ionic Liquid Mixtures Containing Heterodications

DOE PAGES

Lall-Ramnarine, S.; Fernandez, E.; Rodriguez, C.; ...

2016-08-30

This report discusses the transport properties of ionic liquid mixtures that incorporate a series of asymmetrical dications, including heterodications. The dicationic ILs combine either triphenylphosphonium and trimethylammonium cationic sites that are bridged to methylimidazolium or methylpyrrolidinium cationic sites. Mixtures were made of the dicationic bis(trifluoromethylsulfonyl)amide ionic liquids with N-ethoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide. The IL mixtures were characterized for their transport properties (temperature dependent conductivity and viscosity) and thermal properties (melting point and glass transition point).

Phase Diagram of Kob-Andersen-Type Binary Lennard-Jones Mixtures

NASA Astrophysics Data System (ADS)

Pedersen, Ulf R.; Schrøder, Thomas B.; Dyre, Jeppe C.

2018-04-01

The binary Kob-Andersen (KA) Lennard-Jones mixture is the standard model for computational studies of viscous liquids and the glass transition. For very long simulations, the viscous KA system crystallizes, however, by phase separating into a pure A particle phase forming a fcc crystal. We present the thermodynamic phase diagram for KA-type mixtures consisting of up to 50% small (B ) particles showing, in particular, that the melting temperature of the standard KA system at liquid density 1.2 is 1.028(3) in A particle Lennard-Jones units. At large B particle concentrations, the system crystallizes into the CsCl crystal structure. The eutectic corresponding to the fcc and CsCl structures is cutoff in a narrow interval of B particle concentrations around 26% at which the bipyramidal orthorhombic PuBr3 structure is the thermodynamically stable phase. The melting temperature's variation with B particle concentration at two constant pressures, as well as at the constant density 1.2, is estimated from simulations at pressure 10.19 using isomorph theory. Our data demonstrate approximate identity between the melting temperature and the onset temperature below which viscous dynamics appears. Finally, the nature of the solid-liquid interface is briefly discussed.

Electrical Conductivity of Molten DyCl3-NaCl and DyCl3-KCl Systems: An Approach to Structural Interpretations of Rare Earth Chloride Melts

NASA Astrophysics Data System (ADS)

Iwadate, Yasuhiko; Ohkubo, Takahiro

2017-11-01

Electrical conductivities (κs) of molten DyCl3-NaCl and DyCl3-KCl systems were estimated by measuring the impedances of each mixture melt at any temperature and/or frequency. The molar volumes (Vms) were measured by dilatometry and represented as a polynomial empirical equation of temperature and composition. Due to both the properties, the molar conductivities (Λms) were calculated and their temperature and/or composition dependences were discussed from the standpoint of structural features as well. The κs increased curvilinearly with increasing temperature across the whole composition ranges. This trend was also applied to the Λms which was fitted by an Arrhenius-type equation. The relationship of Λms with melt composition was studied and the Λms were found to decrease with increasing composition of DyCl3. These findings were interpreted based on the results of structural science so far reported, and finally, the relationship between Λms and the structures of pure rare earth chloride melts was discussed.

COATED ALLOYS

DOEpatents

Harman, C.G.; O'Bannon, L.S.

1958-07-15

A coating is described for iron group metals and alloys, that is particularly suitable for use with nickel containing alloys. The coating is glassy in nature and consists of a mixture containing an alkali metal oxide, strontium oxide, and silicon oxide. When the glass coated nickel base metal is"fired'' at less than the melting point of the coating, it appears the nlckel diffuses into the vitreous coating, thus providing a closely adherent and protective cladding.

Thermal characteristics of oleochemical carbonate binary mixtures for potential latent heat storage

USDA-ARS?s Scientific Manuscript database

The present study examines the thermal properties of melting and solidification for binary mixtures between dodecyl carbonate (1a), tetradecyl carbonate (1b), hexadecyl carbonate (1c), and octadecyl carbonate (1d) by differential scanning calorimetry (DSC) in order to gain further understanding of t...

Process for solidifying high-level nuclear waste

DOEpatents

Ross, Wayne A.

1978-01-01

The addition of a small amount of reducing agent to a mixture of a high-level radioactive waste calcine and glass frit before the mixture is melted will produce a more homogeneous glass which is leach-resistant and suitable for long-term storage of high-level radioactive waste products.

Cermet crucible for metallurgical processing

DOEpatents

Boring, Christopher P.

1995-01-01

A cermet crucible for metallurgically processing metals having high melting points comprising a body consisting essentially of a mixture of calcium oxide and erbium metal, the mixture comprising calcium oxide in a range between about 50 and 90% by weight and erbium metal in a range between about 10 and 50% by weight.

Decoding DNA labels by melting curve analysis using real-time PCR.

PubMed

Balog, József A; Fehér, Liliána Z; Puskás, László G

2017-12-01

Synthetic DNA has been used as an authentication code for a diverse number of applications. However, existing decoding approaches are based on either DNA sequencing or the determination of DNA length variations. Here, we present a simple alternative protocol for labeling different objects using a small number of short DNA sequences that differ in their melting points. Code amplification and decoding can be done in two steps using quantitative PCR (qPCR). To obtain a DNA barcode with high complexity, we defined 8 template groups, each having 4 different DNA templates, yielding 158 (>2.5 billion) combinations of different individual melting temperature (Tm) values and corresponding ID codes. The reproducibility and specificity of the decoding was confirmed by using the most complex template mixture, which had 32 different products in 8 groups with different Tm values. The industrial applicability of our protocol was also demonstrated by labeling a drone with an oil-based paint containing a predefined DNA code, which was then successfully decoded. The method presented here consists of a simple code system based on a small number of synthetic DNA sequences and a cost-effective, rapid decoding protocol using a few qPCR reactions, enabling a wide range of authentication applications.

Phase equillibria and solidification behaviour in the vanillin- p-anisidine system

NASA Astrophysics Data System (ADS)

Singh, N. B.; Das, S. S.; Gupta, Preeti; Dwivedi, M. K.

2008-12-01

Phase diagram of the vanillin- p-anisidine system has been studied by the thaw melt method. Congruent melting-type phase diagram exhibiting two eutectic points was obtained. Vanillin and p-anisidine react in 1:1 M ratio and form N-(4-methoxy phenyl)-4-hydroxy-3-methoxy phenyl methanimine (NHM) and water. Heats of fusion of pure components and the eutectic mixtures ( E1 and E2) were obtained from DSC studies. Jackson's roughness parameters ( α) were calculated. Excess Gibbs free energy ( GE), excess entropy ( SE) and excess enthalpy ( HE) of mixing of pre-, post- and eutectic mixtures were also calculated by using activity coefficient data. Linear velocities of solidification of components and eutectic mixtures were determined at different undercoolings. The values of excess thermodynamic functions and linear velocity data have indicated the non-ideal nature of the eutectic mixtures. Interaction energies in the gaseous state, calculated from computer simulation, have also indicated that the eutectics are non-ideal mixtures. Microstructural studies of vanillin, p-anisidine and NHM show the formation of broken lamellar type structures. However, for the eutectic E1, an irregular type and for the eutectic E2, a lamellar type structures were obtained. The effect of impurity on the microstructures of eutectic mixtures was also studied.

Production of solid lipid submicron particles for protein delivery using a novel supercritical gas-assisted melting atomization process.

PubMed

Salmaso, Stefano; Elvassore, Nicola; Bertucco, Alberto; Caliceti, Paolo

2009-02-01

A supercritical carbon dioxide micronization technique based on gas-assisted melting atomization has been designed to prepare protein-loaded solid lipid submicron particles. The supercritical process was applied to homogeneous dispersions of insulin in lipid mixtures: (1) tristearin, Tween-80, phosphatidylcholine and 5 kDa PEG (1:0.1:0.9:1 and 1:0.1:0.9:2 weight ratio); and (2) tristearin, dioctyl sulfosuccinate and phosphatidylcholine (1:1:0.5 weight ratio). Optimized process conditions yielded dry nonagglomerated powders with high product recovery (70%, w/w). Dynamic light scattering and transmission electron microscopy showed that two size fractions of particles, with 80-120 and 200-400 nm diameters, were produced. In all final products, dimethylsulfoxide used to prepare the insulin/lipid mixture was below 20 ppm. Protein encapsulation efficiency increased up to 80% as the DMSO content in the insulin/lipid mixture increased. Compared to the particles without PEG, the polymer-containing particles dispersed rapidly in water, and the dispersions were more stable under centrifugation as less than 20% of suspended particles precipitated after extensive centrifugation. In vitro, the protein was slowly released from the formulation without PEG, while a burst and faster release were obtained from the formulations containing PEG. Subcutaneous injection to diabetic mice of insulin extracted from the particles showed that the supercritical process did not impair the protein hypoglycemic activity.

Structural and viscoelastic characterization of ternary mixtures of sunflower oil, saturated monoglycerides and aqueous phases containing different bases.

PubMed

Valoppi, Fabio; Calligaris, Sonia; Barba, Luisa; Nicoli, Maria Cristina

2015-08-01

The structure at different length scales and the viscoelastic properties of ternary mixtures composed of saturated monoglycerides, sunflower oil and aqueous solutions of weak bases (KHCO 3 , NaHCO 3 , and NH 4 HCO 3 ) or strong bases (NaOH and KOH) were investigated. The characteristics of ternary mixtures were studied systematically by using polarized light microscopy, differential scanning calorimetry (DSC), synchrotron X-ray diffraction (XRD) and rheological analysis. Results showed that the base type and concentration greatly affected the structure of the mixtures. The use of strong bases allowed gelled systems to be obtained only at low concentrations (<10mM). On the contrary, the presence of weak bases induced gelling at all concentrations considered (from 1 to 1000mM). The increase of base concentration led to a reduction of the mean droplet diameter and melting temperature. At the same time, the viscoelastic characteristics as a function of base concentration followed a more complex behavior: G' and G″ progressively decreased as the salt concentration increased in a concentration range from 1 to 100mM, while the rheological parameters increased when salt concentration increased from 100 to 1000mM. The structural and viscoelastic behavior of systems prepared with different salts were commonly independent of the cation present in the medium. Results highlight that it is possible to tailor the structure of these gels by using specific bases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Crystallization of D-mannitol in binary mixtures with NaCl: phase diagram and polymorphism.

PubMed

Telang, Chitra; Suryanarayanan, Raj; Yu, Lian

2003-12-01

To study the crystallization, polymorphism, and phase behavior of D-mannitol in binary mixtures with NaCl to better understand their interactions in frozen aqueous solutions. Differential scanning calorimetry, hot-stage microscopy, Raman microscopy, and variable-temperature X-ray diffractometry were used to characterize D-mannitol-NaCl mixtures. NaCl and D-mannitol exhibited significant melt miscibility (up to 7.5% w/w or 0.20 mole fraction of NaCl) and a eutectic phase diagram (eutectic composition 7.5% w/w NaCl; eutectic temperature 150 degrees C for the alpha and beta polymorphs of D-mannitol and 139 degrees C for the delta). The presence of NaCl did not prevent mannitol from crystallizing but, depending on sample size, affected the polymorph crystallized: below 10 mg, delta was obtained; above 100 mg, alpha was obtained. Pure mannitol crystallized under the same conditions first as the delta polymorph and then as the a polymorph, with the latter nucleating on the former. KCl showed similar eutectic points and melt miscibility with D-mannitol as NaCl. LiCl yielded lower eutectic melting points, inhibited the crystallization of D-mannitol during cooling, and enabled the observation of its glass transition. Despite their structural dissimilarity, significant melt miscibility exists between D-mannitol and NaCl. Their phase diagram has been determined and features polymorph-dependent eutectic points. NaCl influences the polymorphic behavior of mannitol, and the effect is linked to the crystallization of mannitol in two polymorphic stages.

Centrifugal air-assisted melt agglomeration for fast-release "granulet" design.

PubMed

Wong, Tin Wui; Musa, Nafisah

2012-07-01

Conventional melt pelletization and granulation processes produce round and dense, and irregularly shaped but porous agglomerates respectively. This study aimed to design centrifugal air-assisted melt agglomeration technology for manufacture of spherical and yet porous "granulets" for ease of downstream manufacturing and enhancing drug release. A bladeless agglomerator, which utilized shear-free air stream to mass the powder mixture of lactose filler, polyethylene glycol binder and poorly water-soluble tolbutamide drug into "granulets", was developed. The inclination angle and number of vane, air-impermeable surface area of air guide, processing temperature, binder content and molecular weight were investigated with reference to "granulet" size, shape, texture and drug release properties. Unlike fluid-bed melt agglomeration with vertical processing air flow, the air stream in the present technology moved centrifugally to roll the processing mass into spherical but porous "granulets" with a drug release propensity higher than physical powder mixture, unprocessed drug and dense pellets prepared using high shear mixer. The fast-release attribute of "granulets" was ascribed to porous matrix formed with a high level of polyethylene glycol as solubilizer. The agglomeration and drug release outcomes of centrifugal air-assisted technology are unmet by the existing high shear and fluid-bed melt agglomeration techniques. Copyright © 2012 Elsevier B.V. All rights reserved.

Coordinated Hard Sphere Mixture (CHaSM): A fast approximate model for oxide and silicate melts at extreme conditions

NASA Astrophysics Data System (ADS)

Wolf, A. S.; Asimow, P. D.; Stevenson, D. J.

2015-12-01

Recent first-principles calculations (e.g. Stixrude, 2009; de Koker, 2013), shock-wave experiments (Mosenfelder, 2009), and diamond-anvil cell investigations (Sanloup, 2013) indicate that silicate melts undergo complex structural evolution at high pressure. The observed increase in cation-coordination (e.g. Karki, 2006; 2007) induces higher compressibilities and lower adiabatic thermal gradients in melts as compared with their solid counterparts. These properties are crucial for understanding the evolution of impact-generated magma oceans, which are dominated by the poorly understood behavior of silicates at mantle pressures and temperatures (e.g. Stixrude et al. 2009). Probing these conditions is difficult for both theory and experiment, especially given the large compositional space (MgO-SiO2-FeO-Al2O3-etc). We develop a new model to understand and predict the behavior of oxide and silicate melts at extreme P-T conditions (Wolf et al., 2015). The Coordinated Hard Sphere Mixture (CHaSM) extends the Hard Sphere mixture model, accounting for the range of coordination states for each cation in the liquid. Using approximate analytic expressions for the hard sphere model, this fast statistical method compliments classical and first-principles methods, providing accurate thermodynamic and structural property predictions for melts. This framework is applied to the MgO system, where model parameters are trained on a collection of crystal polymorphs, producing realistic predictions of coordination evolution and the equation of state of MgO melt over a wide P-T range. Typical Mg-coordination numbers are predicted to evolve continuously from 5.25 (0 GPa) to 8.5 (250 GPa), comparing favorably with first-principles Molecular Dynamics (MD) simulations. We begin extending the model to a simplified mantle chemistry using empirical potentials (generally accurate over moderate pressure ranges, <~30 GPa), yielding predictions rooted in statistical representations of melt structure that compare well with more time-consuming classical MD calculations. This approach also sheds light on the universality of the increasing Grüneisen parameter trend for liquids (opposite that of solids), which directly reflects their progressive evolution toward more compact solid-like structures upon compression.

Phase diagram of ammonium nitrate

NASA Astrophysics Data System (ADS)

Dunuwille, Mihindra; Yoo, Choong-Shik

2013-12-01

Ammonium Nitrate (AN) is a fertilizer, yet becomes an explosive upon a small addition of chemical impurities. The origin of enhanced chemical sensitivity in impure AN (or AN mixtures) is not well understood, posing significant safety issues in using AN even today. To remedy the situation, we have carried out an extensive study to investigate the phase stability of AN and its mixtures with hexane (ANFO-AN mixed with fuel oil) and Aluminum (Ammonal) at high pressures and temperatures, using diamond anvil cells (DAC) and micro-Raman spectroscopy. The results indicate that pure AN decomposes to N2, N2O, and H2O at the onset of the melt, whereas the mixtures, ANFO and Ammonal, decompose at substantially lower temperatures. The present results also confirm the recently proposed phase IV-IV' transition above 17 GPa and provide new constraints for the melting and phase diagram of AN to 40 GPa and 400°C.

Differential scanning calorimetric study of nonionic surfactant mixtures with a room temperature ionic liquid, bmimBF4.

PubMed

Inoue, Tohru; Higuchi, Yuka; Misono, Takeshi

2009-10-01

The melting behavior of polyethyleneglycol dodecyl ethers (C(12)E(6), C(12)E(7), and C(12)E(8)) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), was investigated by means of differential scanning calorimetry (DSC). The melting temperature as a function of the surfactant concentration, combined with the cmc curve and cloud point curve, provided phase diagrams for the surfactant/bmimBF(4) mixtures in solvent-rich region. The characteristic feature of the mixtures is an existence of the Krafft temperature which is usually not observed with aqueous solutions of nonionic surfactants. The heat of fusion as a function of the surfactant concentration provided the interaction energy between the surfactant and bmimBF(4). The interaction energy shows a linear dependence on the length of polyoxyethylene (POE) chain of the surfactants, which suggests that the solvation takes place around the POE chain.

Enzymatic synthesis of cocoa butter equivalent from olive oil and palmitic-stearic fatty acid mixture.

PubMed

Mohamed, Ibrahim O

2015-01-01

The main goal of the present research is to restructure olive oil triacylglycerol (TAG) using enzymatic acidolysis reaction to produce structured lipids that is close to cocoa butter in terms of TAG structure and melting characteristics. Lipase-catalyzed acidolysis of refined olive oil with a mixture of palmitic-stearic acids at different substrate ratios was performed in an agitated batch reactor maintained at constant temperature and agitation speed. The reaction attained steady-state conversion in about 5 h with an overall conversion of 92.6 % for the olive oil major triacylglycerol 1-palmitoy-2,3-dioleoyl glycerol (POO). The five major TAGs of the structured lipids produced with substrate mass ratio of 1:3 (olive oil/palmitic-stearic fatty acid mixture) were close to that of the cocoa butter with melting temperature between 32.6 and 37.7 °C. The proposed kinetics model used fits the experimental data very well.

Melting of municipal solid waste incinerator fly ash by waste-derived thermite reaction.

PubMed

Wang, Kuen-Sheng; Lin, Kae-Long; Lee, Ching-Hwa

2009-02-15

This work describes a novel approach for melting municipal solid waste incinerator (MSWI) fly ash, based on self-propagating reactions, by using energy-efficient simulated waste-derived thermite. The self-propagating characteristics, the properties of the recycled alloy and slag and the partitioning of heavy metals during the process are also studied. Experimental results demonstrate that the mix ratio of fly ash to the starting mixture of less than 30% supports the development of the self-propagating reaction with a melting temperature of 1350-2200 degrees C. Furthermore, metallic iron (or alloy) and the slag were retrieved after activation of the thermite reactions among the starting mixtures. It was noted that more than 91wt.% of iron was retrieved as alloy and the rest of non-reductive oxides as slag. During the thermite reactions, the partition of heavy metals to the SFA and flue gas varied with the characteristics of the target metals: Cd was mainly partitioned to flue gas (75-82%), and partition slightly increased with the increasing fly ash ratio; Pb and Zn, were mainly partitioned to the SFA, and the partition increased with increasing fly ash ratio; Cu was partitioned to the SFA (18-31%) and was not found in the flue gas; and moreover stable Cr and Ni were not identified in both the SFA and flue gas. On the other hand, the determined TCLP leaching concentrations were all well within the current regulatory thresholds, despite the various FA ratios. This suggests that the vitrified fly ash samples were environmental safe in heavy metal leaching. The results of this study suggested that melting of municipal solid waste incinerator fly ash by waste-derived thermite reactions was a feasible approach not only energy-beneficial but also environmental-safe.

Low-Absorption Liquid Crystals for Infrared Beam Steering

DTIC Science & Technology

2013-10-22

Low absorption, MWIR, chlorinated liquid crystals, fluorination, FTIR, eutectic mixture, deuteration, nematic phase, birefringence, overtone...absorption compounds for LWIR and SWIR are also investigated. Key words: Low absorption, MWIR, chlorinated liquid crystals, fluorination, FTIR, eutectic ...the melting point significantly. We did careful investigation and formed a eutectic mixture consisting of five fluorinated compounds without any

Cermet crucible for metallurgical processing

DOEpatents

Boring, C.P.

1995-02-14

A cermet crucible is disclosed for metallurgically processing metals having high melting points comprising a body consisting essentially of a mixture of calcium oxide and erbium metal, the mixture comprising calcium oxide in a range between about 50 and 90% by weight and erbium metal in a range between about 10 and 50% by weight.

Dynamic Melting of Freezing Droplets on Ultraslippery Superhydrophobic Surfaces.

PubMed

Chu, Fuqiang; Wu, Xiaomin; Wang, Lingli

2017-03-08

Condensed droplet freezing and freezing droplet melting phenomena on the prepared ultraslippery superhydrophobic surface were observed and discussed in this study. Although the freezing delay performance of the surface is common, the melting of the freezing droplets on the surface is quite interesting. Three self-propelled movements of the melting droplets (ice- water mixture) were found including the droplet rotating, the droplet jumping, and the droplet sliding. The melting droplet rotating, which means that the melting droplet rotates spontaneously on the superhydrophobic surface like a spinning top, is first reported in this study and may have some potential applications in various engineering fields. The melting droplet jumping and sliding are similar to those occurring during condensation but have larger size scale and motion scale, as the melting droplets have extra-large specific surface area with much more surface energy available. These self-propelled movements make all the melting droplets on the superhydrophobic surface dynamic, easily removed, which may be promising for the anti-icing/frosting applications.

Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

DOEpatents

Anderson, Iver E.; Lograsso, Barbara K.; Ellis, Timothy W.

1994-01-01

A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material.

Species identification in meat products: A new screening method based on high resolution melting analysis of cyt b gene.

PubMed

Lopez-Oceja, A; Nuñez, C; Baeta, M; Gamarra, D; de Pancorbo, M M

2017-12-15

Meat adulteration by substitution with lower value products and/or mislabeling involves economic, health, quality and socio-religious issues. Therefore, identification and traceability of meat species has become an important subject to detect possible fraudulent practices. In the present study the development of a high resolution melt (HRM) screening method for the identification of eight common meat species is reported. Samples from Bos taurus, Ovis aries, Sus scrofa domestica, Equus caballus, Oryctolagus cuniculus, Gallus gallus domesticus, Meleagris gallopavo and Coturnix coturnix were analyzed through the amplification of a 148 bp fragment from the cyt b gene with a universal primer pair in HRM analyses. Melting profiles from each species, as well as from several DNA mixtures of these species and blind samples, allowed a successful species differentiation. The results demonstrated that the HRM method here proposed is a fast, reliable, and low-cost screening technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

High energy product permanent magnet having improved intrinsic coercivity and method of making same

DOEpatents

Ramesh, Ramamoorthy; Thomas, Gareth

1990-01-01

A high energy rare earth-ferromagnetic metal permanent magnet is disclosed which is characterized by improved intrinsic coercivity and is made by forming a particulate mixture of a permanent magnet alloy comprising one or more rare earth elements and one or more ferromagnetic metals and forming a second particulate mixture of a sintering alloy consisting essentially of 92-98 wt. % of one or more rare earth elements selected from the class consisting of Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and mixtures of two or more of such rare earth elements, and 2-8 wt. % of one or more alloying metals selected from the class consisting of Al, Nb, Zr, V, Ta, Mo, and mixtures of two or more of such metals. The permanent magnet alloy particles and sintering aid alloy are mixed together and magnetically oriented by immersing the mixture in an axially aligned magnetic field while cold pressing the mixture. The compressed mixture is then sintered at a temperature above the melting point of the sintering aid and below the melting point of the permanent magnet alloy to thereby coat the particle surfaces of the permanent magnetic alloy particles with the sintering aid while inhibiting migration of the rare earth element in the sintering aid into the permanent magnet alloy particles to thereby raise the intrinsic coercivity of the permanent magnet alloy without substantially lowering the high energy of the permanent magnet alloy.

Development of a fast, lean and agile direct pelletization process using experimental design techniques.

PubMed

Politis, Stavros N; Rekkas, Dimitrios M

2017-04-01

A novel hot melt direct pelletization method was developed, characterized and optimized, using statistical thinking and experimental design tools. Mixtures of carnauba wax (CW) and HPMC K100M were spheronized using melted gelucire 50-13 as a binding material (BM). Experimentation was performed sequentially; a fractional factorial design was set up initially to screen the factors affecting the process, namely spray rate, quantity of BM, rotor speed, type of rotor disk, lubricant-glidant presence, additional spheronization time, powder feeding rate and quantity. From the eight factors assessed, three were further studied during process optimization (spray rate, quantity of BM and powder feeding rate), at different ratios of the solid mixture of CW and HPMC K100M. The study demonstrated that the novel hot melt process is fast, efficient, reproducible and predictable. Therefore, it can be adopted in a lean and agile manufacturing setting for the production of flexible pellet dosage forms with various release rates easily customized between immediate and modified delivery.

Process for alloying uranium and niobium

DOEpatents

Holcombe, Cressie E.; Northcutt, Jr., Walter G.; Masters, David R.; Chapman, Lloyd R.

1991-01-01

Alloys such as U-6Nb are prepared by forming a stacked sandwich array of uraniun sheets and niobium powder disposed in layers between the sheets, heating the array in a vacuum induction melting furnace to a temperature such as to melt the uranium, holding the resulting mixture at a temperature above the melting point of uranium until the niobium dissolves in the uranium, and casting the uranium-niobium solution. Compositional uniformity in the alloy product is enabled by use of the sandwich structure of uranium sheets and niobium powder.

The effects of polymer carrier, hot melt extrusion process and downstream processing parameters on the moisture sorption properties of amorphous solid dispersions.

PubMed

Feng, Xin; Vo, Anh; Patil, Hemlata; Tiwari, Roshan V; Alshetaili, Abdullah S; Pimparade, Manjeet B; Repka, Michael A

2016-05-01

The aim of this study was to evaluate the effect of polymer carrier, hot melt extrusion and downstream processing parameters on the water uptake properties of amorphous solid dispersions. Three polymers and a model drug were used to prepare amorphous solid dispersions utilizing the hot melt extrusion technology. The sorption-desorption isotherms of solid dispersions and their physical mixtures were measured by the dynamic vapour sorption system, and the effects of polymer hydrophobicity, hygroscopicity, molecular weight and the hot melt extrusion process were investigated. Fourier transform infrared (FTIR) imaging was performed to understand the phase separation driven by the moisture. Solid dispersions with polymeric carriers with lower hydrophilicity, hygroscopicity and higher molecular weight could sorb less moisture under the high relative humidity (RH) conditions. The water uptake ability of polymer-drug solid dispersion systems were decreased compared with the physical mixture after hot melt extrusion, which might be due to the decreased surface area and porosity. The FTIR imaging indicated that the homogeneity of the drug molecularly dispersed within the polymer matrix was changed after exposure to high RH. Understanding the effect of formulation and processing on the moisture sorption properties of solid dispersions is essential for the development of drug products with desired physical and chemical stability. © 2015 Royal Pharmaceutical Society.

Chemical and physical analyses of wax ester properties

PubMed Central

Patel, Sejal; Nelson, Dennis R.; Gibbs, Allen G.

2001-01-01

Wax esters are major constituents of the surface lipids in many terrestrial arthropods, but their study is complicated by their diversity. We developed a procedure for quantifying isomers in mixtures of straight-chain saturated and unsaturated wax esters having the same molecular weights, using single-ion monitoring of the total ion current data from gas chromatography-mass spectrometry. We examined the biological consequences of structural differences by measuring the melting temperatures, Tm, of >60 synthetic wax esters, containing 26–48 carbon atoms. Compounds containing saturated alcohol and acid moieties melted at 38–73°C. The main factor affecting Tm was the total chain length of the wax ester, but the placement of the ester bond also affected Tm. Insertion of a double bond into either the alcohol or acid moiety decreased Tm by ∼30°C. Simple mixtures of wax esters with n-alkanes melted several °C lower than predicted from the melting points of the component lipids. Our results indicate that the wax esters of primary alcohols that are most typically found on the cuticle of terrestrial arthropods occur in a solid state under physiological conditions, thereby conferring greater waterproofing. Wax esters of secondary alcohols, which occur on melanopline grasshoppers, melted >60°C below primary esters of the same molecular weight and reduced Tm of the total surface lipids to environmental values. PMID:15455064

PRODUCTION OF URANIUM MONOCARBIDE

DOEpatents

Powers, R.M.

1962-07-24

A method of making essentially stoichiometric uranium monocarbide by pelletizing a mixture of uranium tetrafluoride, silicon, and carbon and reacting the mixture at a temperature of approximately 1500 to 1700 deg C until the reaction goes to completion, forming uranium monocarbide powder and volatile silicon tetrafluoride, is described. The powder is then melted to produce uranium monocarbide in massive form. (AEC)

Chemical and Electrochemical Processing of Aluminum Dross Using Molten Salts

NASA Astrophysics Data System (ADS)

Yan, Xiao Y.

2008-04-01

A novel molten salt process was investigated, where Al, as metal or contained in Al2O3 and AlN, was recovered from Al dross by chemical or direct electrochemical reduction in electrolytic cells. Electrolysis experiments were carried out under argon at temperatures from 1123 to 1243 K. In order to better understand the reduction behavior, the as-received Al dross was simulated using simplified systems, including pure Al2O3, pure AlN, an Al2O3/AlN binary mixture, and an Al2O3/AlN/Al ternary mixture. The reduction of the as-received dross was also studied experimentally. The studies showed that solid Al2O3 was chemically reduced by the Ca in a Ca-saturated Ca-CaCl2 melt to form Al2Ca or electrochemically reduced to Al-rich Al-Ca alloys and that the Al value in the Al2O3 was easily recovered from the Al drosses. It was found experimentally that solid AlN in the drosses could not be calciothermically reduced to any extent, consistent with thermodynamic evaluations. It was also found that the direct electrochemical reduction of the AlN in the drosses was confined to three phase boundaries (3PBs) between the AlN, the electrolyte, and the current collector and could not be enhanced by using the LiCl-containing chloride melt or the chloride-fluoride melts studied. The presence of Al powder in the Al2O3/AlN mixture facilitated the direct electrochemical reduction of both Al2O3 and AlN. The reduction mechanisms are discussed based upon the present experimental observations. Flow sheets for recovering the metallic Al and the Al in the Al2O3 and AlN from Al dross are finally proposed.

Barium iodide and strontium iodide crystals and scintillators implementing the same

DOEpatents

Payne, Stephen A.; Cherepy, Nerine; Pedrini, Christian; Burger, Arnold

2016-09-13

In one embodiment, a crystal includes at least one metal halide; and an activator dopant comprising ytterbium. In another general embodiment, a scintillator optic includes: at least one metal halide doped with a plurality of activators, the plurality of activators comprising: a first activator comprising europium, and a second activator comprising ytterbium. In yet another general embodiment, a method for manufacturing a crystal suitable for use in a scintillator includes mixing one or more salts with a source of at least one dopant activator comprising ytterbium; heating the mixture above a melting point of the salt(s); and cooling the heated mixture to a temperature below the melting point of the salts. Additional materials, systems, and methods are presented.

Gas atomization synthesis of refractory or intermetallic compounds and supersaturated solid solutions

DOEpatents

Anderson, I.E.; Lograsso, B.K.; Ellis, T.W.

1994-11-29

A metallic melt is atomized using a high pressure atomizing gas wherein the temperature of the melt and the composition of the atomizing gas are selected such that the gas and melt react in the atomization spray zone to form a refractory or intermetallic compound in the as-atomized powder particles. A metallic melt is also atomized using a high pressure atomizing gas mixture gas wherein the temperature of the melt and the ratio of a reactive gas to a carrier gas are selected to form powder particles comprising a supersaturated solid solution of the atomic species of the reactive gas in the particles. The powder particles are then heat treated to precipitate dispersoids in-situ therein to form a dispersion strengthened material. 9 figures.

URANIUM SEPARATION PROCESS

DOEpatents

Lyon, W.L.

1962-04-17

A method of separating uranium oxides from PuO/sub 2/, ThO/sub 2/, and other actinide oxides is described. The oxide mixture is suspended in a fused salt melt and a chlorinating agent such as chlorine gas or phosgene is sparged through the suspension. Uranium oxides are selectively chlorinated and dissolve in the melt, which may then be filtered to remove the unchlorinated oxides of the other actinides. (AEC)

Method for forming an abrasive surface on a tool

DOEpatents

Seals, Roland D.; White, Rickey L.; Swindeman, Catherine J.; Kahl, W. Keith

1999-01-01

A method for fabricating a tool used in cutting, grinding and machining operations, is provided. The method is used to deposit a mixture comprising an abrasive material and a bonding material on a tool surface. The materials are propelled toward the receiving surface of the tool substrate using a thermal spray process. The thermal spray process melts the bonding material portion of the mixture, but not the abrasive material. Upon impacting the tool surface, the mixture or composition solidifies to form a hard abrasive tool coating.

METHOD OF SEPARATING URANIUM FROM ALLOYS

DOEpatents

Chiotti, P.; Shoemaker, H.E.

1960-06-28

Uranium can be recovered from metallic uraniumthorium mixtures containing uranium in comparatively small amounts. The method of recovery comprises adding a quantity of magnesium to a mass to obtain a content of from 48 to 85% by weight; melting and forming a magnesium-thorium alloy at a temperature of between 585 and 800 deg C; agitating the mixture, allowing the mixture to settle whereby two phases, a thorium-containing magnesium-rich liquid phase and a solid uranium-rich phase, are formed; and separating the two phases.

Chromonic liquid crystalline nematic phase exhibited in binary mixture of two liquid crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Govindaiah, T. N., E-mail: tngovi.phy@gmail.com; Sreepad, H. R.; Sridhar, K. N.

2015-06-24

A binary mixture of abietic acid and orthophosphoric acid (H{sub 3}PO{sub 4}) exhibits co-existence of biphasic region of Nematic+Isotropic (N+I), lyotropic Nematic (ND) and Smectic-G (SmG) phases. The mixture exhibits N+I, N and SmG phases at different concentrations and at different temperatures. Mixtures with all concentrations of abietic acid exhibit I→N+I→N→SmG phases sequentially when the specimen is cooled from its isotropic melt. These phases have been characterized by using differential scanning calorimetric, X-ray diffraction, and optical texture studies.

Obtaining Crack-free WC-Co Alloys by Selective Laser Melting

NASA Astrophysics Data System (ADS)

Khmyrov, R. S.; Safronov, V. A.; Gusarov, A. V.

Standard hardmetals of WC-Co system are brittle and often crack at selective laser melting (SLM). The objective of this study is to estimate the range of WC/Co ratio where cracking can be avoided. Micron-sized Co powder was mixed with WC nanopowder in a ball mill to obtain uniform distribution of WC over the surface of Co particles. Continuous layers of remelted material on the surface of a hardmetal plate were obtained from this composite powder by SLM at 1.07μm wavelength. The layers have satisfactory porosity and are well bound to the substrate. The chemical composition of the layers matches the composition of the initial powder mixtures. The powder mixture with 25wt.%WC can be used for SLM to obtain materials without cracks. The powder mixture with 50wt.%WC cracks because of formation of brittle W3Co3C phase. Cracking can considerably reduce the mechanical strength, so that the use of this composition is not advised.

Enhanced performance and interfacial investigation of mineral-based composite phase change materials for thermal energy storage.

PubMed

Li, Chuanchang; Fu, Liangjie; Ouyang, Jing; Yang, Huaming

2013-01-01

A novel mineral-based composite phase change materials (PCMs) was prepared via vacuum impregnation method assisted with microwave-acid treatment of the graphite (G) and bentonite (B) mixture. Graphite and microwave-acid treated bentonite mixture (GBm) had more loading capacity and higher crystallinity of stearic acid (SA) in the SA/GBm composite. The SA/GBm composite showed an enhanced thermal storage capacity, latent heats for melting and freezing (84.64 and 84.14 J/g) was higher than those of SA/B sample (48.43 and 47.13 J/g, respectively). Addition of graphite was beneficial to the enhancement in thermal conductivity of the SA/GBm composite, which could reach 0.77 W/m K, 31% higher than SA/B and 196% than pure SA. Furthermore, atomic-level interfaces between SA and support surfaces were depicted, and the mechanism of enhanced thermal storage properties was in detail investigated.

Use of the melting curve assay as a means for high-throughput quantification of Illumina sequencing libraries.

PubMed

Shinozuka, Hiroshi; Forster, John W

2016-01-01

Background. Multiplexed sequencing is commonly performed on massively parallel short-read sequencing platforms such as Illumina, and the efficiency of library normalisation can affect the quality of the output dataset. Although several library normalisation approaches have been established, none are ideal for highly multiplexed sequencing due to issues of cost and/or processing time. Methods. An inexpensive and high-throughput library quantification method has been developed, based on an adaptation of the melting curve assay. Sequencing libraries were subjected to the assay using the Bio-Rad Laboratories CFX Connect(TM) Real-Time PCR Detection System. The library quantity was calculated through summation of reduction of relative fluorescence units between 86 and 95 °C. Results.PCR-enriched sequencing libraries are suitable for this quantification without pre-purification of DNA. Short DNA molecules, which ideally should be eliminated from the library for subsequent processing, were differentiated from the target DNA in a mixture on the basis of differences in melting temperature. Quantification results for long sequences targeted using the melting curve assay were correlated with those from existing methods (R (2) > 0.77), and that observed from MiSeq sequencing (R (2) = 0.82). Discussion.The results of multiplexed sequencing suggested that the normalisation performance of the described method is equivalent to that of another recently reported high-throughput bead-based method, BeNUS. However, costs for the melting curve assay are considerably lower and processing times shorter than those of other existing methods, suggesting greater suitability for highly multiplexed sequencing applications.

Reactive Melt Extrusion To Improve the Dissolution Performance and Physical Stability of Naproxen Amorphous Solid Dispersions.

PubMed

Liu, Xu; Zhou, Lin; Zhang, Feng

2017-03-06

The purpose of this study was to investigate the reaction between naproxen (NPX) and meglumine (MEG) at elevated temperature and to study the effect of this reaction on the physical stabilities and in vitro drug-release properties of melt-extruded naproxen amorphous solid dispersions (ASDs). Differential scanning calorimetry, hot-stage polarized light microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses demonstrated that in situ salt formation with proton transfer between NPX and MEG occurred at elevated temperature during the melt extrusion process. The amorphous NPX-MEG salt was physically most stable when two components were present at a 1:1 molar ratio. Polymeric carriers, including povidone, copovidone, and SOLUPLUS, did not interfere with the reaction between NPX and MEG during melt extrusion. Compared to the traditional NPX ASDs consisting of NPX and polymer only, NPX-MEG ASDs were physically more stable and remained amorphous following four months storage at 40 °C and 75% RH (relative humidity). Based on nonsink dissolution testing and polarized light microscopy analyses, we concluded that the conventional NPX ASDs composed of NPX and polymers failed to improve the NPX dissolution rate due to the rapid recrystallization of NPX in contact with aqueous medium. The dissolution rate of NPX-MEG ASDs was two times greater than the corresponding physical mixtures and conventional NPX ASDs. This study demonstrated that the acid-base reaction between NPX and MEG during melt extrusion significantly improved the physical stability and the dissolution rate of NPX ASDs.

Ion solvation in polymer blends and block copolymer melts: effects of chain length and connectivity on the reorganization of dipoles.

PubMed

Nakamura, Issei

2014-05-29

We studied the thermodynamic properties of ion solvation in polymer blends and block copolymer melts and developed a dipolar self-consistent field theory for polymer mixtures. Our theory accounts for the chain connectivity of polymerized monomers, the compressibility of the liquid mixtures under electrostriction, the permanent and induced dipole moments of monomers, and the resultant dielectric contrast among species. In our coarse-grained model, dipoles are attached to the monomers and allowed to rotate freely in response to electrostatic fields. We demonstrate that a strong electrostatic field near an ion reorganizes dipolar monomers, resulting in nonmonotonic changes in the volume fraction profile and the dielectric function of the polymers with respect to those of simple liquid mixtures. For the parameter sets used, the spatial variations near an ion can be in the range of 1 nm or larger, producing significant differences in the solvation energy among simple liquid mixtures, polymer blends, and block copolymers. The solvation energy of an ion depends substantially on the chain length in block copolymers; thus, our theory predicts the preferential solvation of ions arising from differences in chain length.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathur, Anoop

A key technological issue facing the success of future Concentrating Solar Thermal Power (CSP) plants is creating an economical Thermal Energy Storage (TES) system. Current TES systems use either sensible heat in fluids such as oil, or molten salts, or use thermal stratification in a dual-media consisting of a solid and a heat-transfer fluid. However, utilizing the heat of fusion in inorganic molten salt mixtures in addition to sensible heat , as in a Phase change material (PCM)-based TES, can significantly increase the energy density of storage requiring less salt and smaller containers. A major issue that is preventing themore » commercial use of PCM-based TES is that it is difficult to discharge the latent heat stored in the PCM melt. This is because when heat is extracted, the melt solidifies onto the heat exchanger surface decreasing the heat transfer. Even a few millimeters of thickness of solid material on heat transfer surface results in a large drop in heat transfer due to the low thermal conductivity of solid PCM. Thus, to maintain the desired heat rate, the heat exchange area must be large which increases cost. This project demonstrated that the heat transfer coefficient can be increase ten-fold by using forced convection by pumping a hyper-eutectic salt mixture over specially coated heat exchanger tubes. However,only 15% of the latent heat is used against a goal of 40% resulting in a projected cost savings of only 17% against a goal of 30%. Based on the failure mode effect analysis and experience with pumping salt at near freezing point significant care must be used during operation which can increase the operating costs. Therefore, we conclude the savings are marginal to justify using this concept for PCM-TES over a two-tank TES. The report documents the specialty coatings, the composition and morphology of hypereutectic salt mixtures and the results from the experiment conducted with the active heat exchanger along with the lessons learnt during experimentation.« less

Cu Nanoparticles Improved Thermal Property of Form-Stable Phase Change Materials Made with Carbon Nanofibers and LA-MA-SA Eutectic Mixture.

PubMed

Song, Xiaofei; Cai, Yibing; Huang, Cong; Gu, Ying; Zhang, Junhao; Qiao, Hui; Wei, Qufu

2018-04-01

A novel form-stable phase change materials (FSPCMs) was fabricated by incorporating fatty acid eutectics with electrospun carbon nanofibers (CNFs) surface-attached with copper (Cu) nanoparticles. Three different Cu/CNFs mats were made through combining the technique and principle of electrospinning, pre-oxidation/carbonization and in-situ reduction, while lauric-myristic-stearic acid (LA-MA-SA) ternary eutectic mixture was prepared as the model PCM. The morphology and crystal structure of Cu/CNFs were characterized by Fourier transfer infrared (FT-IR) spectra, Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy dispersive spectroscopy (EDS), respectively. The results showed that Cu nanoparticles dispersed uniformly on the surface of CNFs mats without agglomeration, and Cu/CNFs mats could provide the mechanical support for FSPCMs and effectively prevent the flow/leakage of molten fatty acid. Morphological structures, as well as the properties of thermal energy storage and thermal energy storage/retrieval rates, of the resulting FSPCMs were investigated by SEM, Differential scanning calorimetry (DSC), and measurement of melting/freezing times, respectively. The results indicated that the fabricated FSPCMs exhibited desired structural morphology, and LA-MA-SA well dispersed in three-dimensional porous structure of Cu/CNFs mats. The melting and crystallization enthalpies of the fabricated FSPCMs were in the range of 117.1-140.7 kJ/kg and 117.2-142.4 kJ/kg, respectively. In comparison with melting/freezing times of LA-MA-SA ternary eutectic mixture, the melting/freezing times of fabricated FSPCMs were respectively decreased ~27.0-49.2% and ~44.1-63.0%. The fabricated FSPCMs possessed good thermal energy storage/retrieval property, and might have great potential for renewable energy storage applications.

Chondritic Meteorites: Nebular and Parent-Body Formation Processes

NASA Technical Reports Server (NTRS)

Rubin, Alan E.; Lindstrom, David (Technical Monitor)

2002-01-01

It is important to identify features in chondrites that formed as a result of parent-body modification in order to disentangle nebular and asteroidal processes. However, this task is difficult because unmetamorphosed chondritic meteorites are mixtures of diverse components including various types of chondrules, chondrule fragments, refractory and mafic inclusions, metal-sulfide grains and fine-grained matrix material. Shocked chondrites can contain melt pockets, silicate-darkened material, metal veins, silicate melt veins, and impact-melt-rock clasts. This grant paid for several studies that went far in helping to distinguish primitive nebular features from those produced during asteroidal modification processes.

Melt-castable energetic compounds comprising oxadiazoles and methods of production thereof

DOEpatents

Pagoria, Philip F; Zhang, Mao X

2013-11-12

In one embodiment, a melt-castable energetic material comprises at least one of: 3,5-bis(4-nitro-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazole (DNFO), and 3-(4-amino-1,2,5-oxadiazol-3-yl)-5-(4-nitro-1,2,5-oxadiazol-3-yl)-1,2- ,4-oxadiazole (ANFO). In another embodiment, a method for forming a melt-castable energetic material includes reacting 3,5-bis(4-amino-1,2,5-oxadiazol-3-yl)-1,2,4-oxadiazole (DAFO) with oxygen or an oxygen-containing compound to form a mixture of at least: DNFO, and ANFO.

Low-melting point heat transfer fluid

DOEpatents

Cordaro, Joseph Gabriel; Bradshaw, Robert W.

2010-11-09

A low-melting point, heat transfer fluid made of a mixture of five inorganic salts including about 29.1-33.5 mol % LiNO.sub.3, 0-3.9 mol % NaNO.sub.3, 2.4-8.2 mol % KNO.sub.3, 18.6-19.9 mol % NaNO.sub.2, and 40-45.6 mol % KNO.sub.2. These compositions can have liquidus temperatures below 80.degree. C. for some compositions.

The WSTIAC Quarterly. Volume 9, Number 3

DTIC Science & Technology

2010-01-25

program .[8] THE THORIUM FUEL CYCLE AND LFTR POWER PLANT The thorium fuel cycle is based on a series of neutron absorp- tion and beta decay processes...the fig- ure is a graphite matrix moderated MSR reactor with fuel salt mixture (ThF4-U233F4) being circulated by a pump through the core and to a...the core as purified salt. As one of the unique safety features, a melt-plug at the reactor bottom would permit the reactor fluid fuel to be drained

Alkali Metal/Salt Thermal-Energy-Storage Systems

NASA Technical Reports Server (NTRS)

Phillips, Wayne W.; Stearns, John W.

1987-01-01

Proposed thermal-energy-storage system based on mixture of alkali metal and one of its halide salts; metal and salt form slurry of two immiscible melts. Use of slurry expected to prevent incrustations of solidified salts on heat-transfer surfaces that occur where salts alone used. Since incrustations impede heat transfer, system performance improved. In system, charging heat-exchanger surface immersed in lower liquid, rich in halide-salt, phase-charge material. Discharging heat exchanger surface immersed in upper liquid, rich in alkali metal.

Polymorphic Crystallization and Crystalline Reorganization of Poly(l-lactic acid)/Poly(d-lactic acid) Racemic Mixture Influenced by Blending with Poly(vinylidene fluoride).

PubMed

Yu, Chengtao; Han, Lili; Bao, Jianna; Shan, Guorong; Bao, Yongzhong; Pan, Pengju

2016-08-18

The effects of poly(vinylidene fluoride) (PVDF) on the crystallization kinetics, competing formations of homocrystallites (HCs) and stereocomplexes (SCs), polymorphic crystalline structure, and HC-to-SC crystalline reorganization of the poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) racemic mixture were investigated. Even though the PLLA/PDLA/PVDF blends are immiscible, blending with PVDF enhances the crystallization rate and SC formation of PLLA/PDLA components at different temperatures that are higher or lower than the melting temperature of the PVDF component; it also facilitates the HC-to-SC melt reorganization upon heating. The crystallization rate and degree of SC crystallinity (Xc,SC) of PLLA/PDLA components in nonisothermal crystallization increase after immiscible blending with PVDF. At different isothermal crystallization temperatures, the crystallization half-time of PLLA/PDLA components decreases; its spherulitic growth rate and Xc,SC increase as the mass fraction of PVDF increases from 0 to 0.5 in the presence of either a solidified or a molten PVDF phase. The HCs formed in primary crystallization of PLLA/PDLA components melt and recrystallize into SCs upon heating; the HC-to-SC melt reorganization is promoted after blending with PVDF. We proposed that the PVDF-promoted crystallization, SC formation, and HC-to-SC melt reorganization of PLLA/PDLA components in PLLA/PDLA/PVDF blends stem from the enhanced diffusion ability of PLLA and PDLA chains.

Characterization of poly(ethylene oxide) as a drug carrier in hot-melt extrusion.

PubMed

Li, Lei; AbuBaker, Omar; Shao, Zezhi J

2006-09-01

Poly(ethylene oxide) (PEO) as a drug carrier in hot-melt extrusion was studied by using a model drug, nifedipine, in a twin-screw extruder. Binary mixtures of PEO and nifedipine have been shown to be amenable to hot-melting at a temperature as low as 70 degrees C, well below nifedipine's melting point (172 degrees C). Hot-stage microscopy provided visual evidence that nifedipine can form a miscible dispersion with PEO at 120 degrees C. Complete loss of nifedipine crystallinity when extrudated at and above 120 degrees C with a drug loading of 20% (w/w) was further confirmed by differential scanning calorimetry (DSC) and X-ray diffraction. Cross-sectional imaging of the extrudates using scanning electron microscopy indicated homogeneous drug distribution inside PEO when the processing temperature was above 120 degrees C. Raman spectroscopy confirmed drug-PEO interactions at a molecular level. Cryo-milled extrudates showed significant improvement in dissolution rate compared to either pure nifedipine or the physical mixture of PEO and nifedipine. A state of supersaturation was achieved after 10-minute release in pH 6.8 phosphate buffer. Finally, stability study demonstrated that the solid dispersion system is chemically stable for at least 3 months under the conditions of both 25 degrees C/60% RH and 40 degrees C/75% RH. Overall, PEO appears to be a promising aid/carrier to solublize poorly soluble drugs through the formation of solid dispersion via hot-melt extrusion, thereby improving dissolution and absorption.

Metal and polymer melt jet formation by the high-power laser ablation

NASA Astrophysics Data System (ADS)

Yoh, Jack J.; Gojani, Ardian B.

2010-02-01

The laser-induced metal and polymer melt jets are studied experimentally. Two classes of physical phenomena of interest are: first, the process of explosive phase change of laser induced surface ablation and second, the hydrodynamic jetting of liquid melts ejected from a beamed spot. We focus on the dynamic link between these two distinct physical phenomena in a framework of forming and patterning of metallic and polymer jets using a high-power Nd:YAG laser. The microexplosion of ablative spot on a target first forms a pocket of hot liquid melt and then it is followed by a sudden volume change of gas-liquid mixture leading to a pressure-induced spray jet ejection into surrounding medium.

Process for treating fission waste

DOEpatents

Rohrmann, Charles A.; Wick, Oswald J.

1983-01-01

A method is described for the treatment of fission waste. A glass forming agent, a metal oxide, and a reducing agent are mixed with the fission waste and the mixture is heated. After melting, the mixture separates into a glass phase and a metal phase. The glass phase may be used to safely store the fission waste, while the metal phase contains noble metals recovered from the fission waste.

Optical Limiting by Index-Matched Phase-Segregated Mixtures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Exarhos, Gregory J.; Ferris, Kim F.; Manijeh Razeghi, Gail J. Brown

The nonlinear optical response for index-matched, non-absorbing immiscible phases (liquid-solid, liquid-liquid, solid-solid) has been determined by means of open aperture z-scan measurements. In mixtures where one constituent shows a relatively high optical nonlinearity, rapid and reversible transformation to a light-scattering state is observed under conditions where a critical incident light fluence is exceeded. This passive broadband response is induced by a transient change in the dispersive part of the refractive index, and is based upon the Christiansen-Shelyubskii filter that at one time was used as a means to monitor the temperature of glass melts. Modeling studies are used to simulatemore » scattering intensities in such textured composites as a function of composition, microstructure, and constituent optical properties. Results provide a rational approach to the selection of materials for use in these limiters. Challenges to preparing dispersed phase mixtures and their response to 532 nm nanosecond pulsed laser irradiation are described.« less

Phase Behavior of Pyrene and Vinyl Polymers with Aromatic Side Groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kangovi, Gagan N.; Lee, Sangwoo

The phase behavior and thermodynamic properties of mixtures of pyrene and model vinyl polymers with and without aromatic side groups are investigated using differential scanning calorimetry (DSC) measurements. The melting temperature and associated heat of melting of the pyrene crystals in the mixtures are utilized to extract the effective interaction parameters χ and the composition of polymer-rich phases, respectively. The χ of pyrene mixed with polymers with aromatic side groups investigated in this study, polystyrene, poly(2-vinylpyridine), and poly(3-vinylanisole), is less than 0.5 at the melting point of the pyrene crystals, suggesting that pyrene and the polymers with aromatic sides groupsmore » are enthalpically compatible, likely due to aromatic π–π interactions. In contrast, the χ of pyrene mixed with poly(1,4-isoprene) or poly(ethylene-alt-propylene) is larger than 0.5. The DSC measurements also enable characterization of the composition of polymer-rich phases. Interestingly, the polymers with aromatic side groups are found to have more pronounced miscibility with pyrene at symmetric compositions.« less

Space processing of composite materials

NASA Technical Reports Server (NTRS)

Steurer, W. H.; Kaye, S.

1975-01-01

Materials and processes for the testing of aluminum-base fiber and particle composites, and of metal foams under extended-time low-g conditions were investigated. A wetting and dispersion technique was developed, based on the theory that under the absence of a gas phase all solids are wetted by liquids. The process is characterized by a high vacuum environment and a high temperature cycle. Successful wetting and dispersion experiments were carried out with sapphire fibers, whiskers and particles, and with fibers of silicon carbide, pyrolytic graphite and tungsten. The developed process and facilities permit the preparation of a precomposite which serves as sample material for flight experiments. Low-g processing consists then merely in the uniform redistribution of the reinforcements during a melting cycle. For the preparation of metal foams, gas generation by means of a thermally decomposing compound was found most adaptable to flight experiments. For flight experiments, the use of compacted mixture of the component materials limits low-g processing to a simple melt cycle.

Melting mode and source lithology inferred from trace element systematic in historical olivine from Lanzarote, Canary Islands

NASA Astrophysics Data System (ADS)

Gómez-Ulla, Alejandra; Sigmarsson, Olgeir; Guðfinnsson, Guðmundur H.

2017-04-01

Trace element concentrations and ratios in olivine phenocrysts, such as fractionation-corrected Ni x (FeO/MgO) and Fe/Mn, have been shown useful as probes of pyroxenite derived component in mixtures of primary mantle melts (e.g. Sobolev et al., 2007). For instance, higher Ni and lower Mn and Ca contents are expected in partial melts of pyroxenite compared to those of lherzolite. We have measured trace element concentrations in olivine from 1730-1736 AD (Timanfaya) and 1824 AD eruptions in Lanzarote (Canary Islands), which erupted mafic and mantle nodule bearing magmas, ranging in composition from highly silica-undersaturated basanite through alkali basalt to tholeiite. The early basanite exhibit the largest olivine trace element variation covering the range of those from MORB and OIB worldwide, whereas later erupted tholeiite have values typical from pyroxenite derived melts. The Fo value decreased systematically with time during the 1730-36 eruption and the proportion of silica-saturated primary melt increased in the parental magma mixture with time. At the end of the eruption, tholeiite magmas crystallized olivine with, increasing concentrations of Mn and Ca and higher Ca/Al at relatively uniform Ni x (FeO/MgO) and Fe/Mn, all of which is readily explained by increased decompression melting at lower temperature. The basanite from the eruption that took place in 1824 AD has olivine with even higher Fo value and trace element variability similar those of the Timanfaya basanite. The fact that the Lanzarote basanite contain olivine with trace element systematic spanning that of MORB and pyroxenite melt can be explained by CO2-flux melting of a lithologically heterogeneous source, generating the diverse compositions. Initial reactive porous flow through depleted oceanic lithosphere and equilibration with dunitic restite of percolating pyroxenite melt may have amplified the observed Ni depletion in olivine of the earliest basanite. The fact that olivine compositions and basanite magma were reproduced approximately a century later may reflect episodic carbonatic fluxing in the slowly uprising Canarian mantle plume.

Mean-Field Models of Structure and Dispersion of Polymer-nanoparticle Mixtures

DTIC Science & Technology

2010-07-29

out of the seminal descriptions of the wetting and dewetting of polymer melts on polymer brushes advanced by Leibler and coworkers.118,119 Explicitly...using scaling ideas and strong segregation theory calculations they delineated the regions where the matrix polymer wets or dewets the brush. In the...Explicitly, when dewetting of the melt chains is expected ( dry brush). In other words, situations involving long matrix polymers and/or densely grafted

Synthesis of LaMnO3 in molten chlorides: effect of preparation conditions.

PubMed

Vradman, Leonid; Zana, Jonatan; Kirschner, Alon; Herskowitz, Moti

2013-07-14

LaMnO3 perovskite was successfully synthesized in molten chlorides. In order to explore the effect of the molten salt type, NaCl-KCl and LiCl-KCl eutectic mixtures were employed as a liquid medium for the perovskite formation process. The synthesis included heating the La-nitrate, Mn-nitrate and chlorides mixture to above the melting point of the corresponding chlorides. This procedure yielded a LaMnO3 phase integrated in the fused chloride matrix. Washing with water removed the salts completely, yielding pure LaMnO3 perovskite crystals. The synthesis without molten salt at 800 °C yielded several by-products in addition to the LaMnO3 phase, while with LiCl-KCl the pure perovskite phase was obtained at temperatures as low as 600 °C. Variation of temperature in the range 600-800 °C for LiCl-KCl and 700-800 °C for NaCl-KCl had no significant effect either on the morphology or on the particle size of the product. On the other hand, the effect of the molten salt type on the morphology and size of perovskite particles was remarkable. The synthesis in NaCl-KCl resulted in sub-micron LaMnO3 particles with shapes that range from truncated hexahedrons to spheres, while in LiCl-KCl mostly cubic particles of up to 2-microns were obtained. The effect of the molten salt type on LaMnO3 perovskite formation is explained based on the nucleation and crystal growth model and difference in the melting point of eutectic mixtures.

Advanced stable lipid-based formulations for a patient-centric product design.

PubMed

Becker, Karin; Saurugger, Eva-Maria; Kienberger, Diana; Lopes, Diogo; Haack, Detlev; Köberle, Martin; Stehr, Michael; Lochmann, Dirk; Zimmer, Andreas; Salar-Behzadi, Sharareh

2016-01-30

Multiparticulate dosage forms are a recent strategy to meet the special needs of children, elderly people and patients suffering from dysphagia. Our study presents a novel and cost-efficient approach for the manufacturing of a taste-masked multiparticulate system with a stable immediate release profile by applying lipid-based excipients in a solvent-free hot melt coating process. The thermosensitive N-acetylcysteine (N-ac) was used as model drug and hot-melt coated with a mixture of tripalmitin and polysorbate 65. A predictive in vitro method for the evaluation of the taste masking efficiency was developed based on the deprotonation of the carboxyl group of N-ac and the decline of pH, responsible for the unpleasant sour taste of the compound. The method was confirmed using in vivo studies. Differential scanning calorimetry and X-ray scattering experiments revealed polymorphic transformation and its dependency on transformation time, temperature and emulsifier concentration. During the process, the coating was transformed almost completely into the stable β-polymorph, leading to an unaltered dissolution profile during storage. A statistical design was conducted that revealed the critical process parameters affecting the taste masking efficiency and drug release. This study shows the successful application of solvent-free hot-melt coating in the development of a taste-masked and stable formulation. Copyright © 2015 Elsevier B.V. All rights reserved.

An experimental investigation of agglutinate melting mechanisms - Shocked mixtures of sodium and potassium feldspars

NASA Technical Reports Server (NTRS)

Simon, S. B.; Papike, J. J.; Horz, F.; See, T. H.

1985-01-01

The results of an experiment designed to test the validity of the model for agglutinate formation involving fusion of the finest fraction or F3 are reported. Impact glasses were formed from various mixes of orthoclase and albite powders, which were used as analogs for soils with chemically constrasting coarse and fine fractions. The results showed that the single most important factor displacing the composition of a small-scale impact melt from the bulk composition of the source regolith is the fractionated composition of the finest soil fraction. Volatile loss and the amount of melting, which in turn are determined by the degree of shock, are also important. As predicted by the model, the lower pressure melts are the most fractionated, and higher pressure is accompanied by increased melting causing glass compositions to approach the bulk. In general, the systematics predicted by the model are observed; the model appears to be valid.

Crystallization and melting properties of mixtures of milk fat stearin and omega-3 rich oils.

PubMed

Li, Bing-Zheng; Truong, Tuyen; Bhandari, Bhesh

2017-03-01

Solid milk fat stearin (S 25 ) can be a promising oxidation retarder due to its capacity to entrap liquid oils, especially for incorporating omega-3 (ω-3) rich oils into dairy products. Thermal properties of S 25 /ω-3 rich oil mixtures are necessary for such application. The effects of S 25 on the crystallization and melting behaviours of ω-3 rich oils, namely fish oil (FO), linseed oil (LO) and krill oil (KO), were investigated by differential scanning calorimetry (DSC). Thermograms showed that with S 25 concentration increasing, transitions of FO and LO shifted to lower and largely to higher temperatures, respectively, while crystallization temperature of KO slightly decreased. Negative, positive and low values of interaction enthalpy (ΔH int ) suggested the adverse, beneficial and limited effect of S 25 on the crystallization of S 25 /FO, S 25 /LO and S 25 /KO mixtures, respectively. LO could have the best oxidative stability upon the addition of S 25 since their interactions facilitated earlier and stronger crystallization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Method and apparatus for melting metals

DOEpatents

Moore, Alan F.; Schechter, Donald E.; Morrow, Marvin Stanley

2006-03-14

A method and apparatus for melting metals uses microwave energy as the primary source of heat. The metal or mixture of metals are placed in a ceramic crucible which couples, at least partially, with the microwaves to be used. The crucible is encased in a ceramic casket for insulation and placed within a microwave chamber. The chamber may be evacuated and refilled to exclude oxygen. After melting, the crucible may be removed for pouring or poured within the chamber by dripping or running into a heated mold within the chamber. Apparent coupling of the microwaves with softened or molten metal produces high temperatures with great energy savings.

Process for treating fission waste. [Patent application

DOEpatents

Rohrmann, C.A.; Wick, O.J.

1981-11-17

A method is described for the treatment of fission waste. A glass forming agent, a metal oxide, and a reducing agent are mixed with the fission waste and the mixture is heated. After melting, the mixture separates into a glass phase and a metal phase. The glass phase may be used to safely store the fission waste, while the metal phase contains noble metals recovered from the fission waste.

Large single crystal quaternary alloys of IB-IIIA-Se/sub 2/ and methods of synthesizing the same

DOEpatents

Ciszek, T.F.

1986-07-15

New alloys of Cu/sub x/Ag/sub (1-x)/InSe/sub 2/ (where x ranges between 0 and 1 and preferably has a value of about 0.75) and CuIn/sub y/Ga/sub (1-y)/Se/sub 2/ (where y ranges between 0 and 1 and preferably has a value of about 0.90) in the form of single crystals with enhanced structure perfection, which crystals are substantially free of fissures, are disclosed. Processes are disclosed for preparing the new alloys of Cu/sub x/Ag/sub (1-x)/InSe/sub 2/. The process includes placing stoichiometric quantities of a Cu, Ag, In, and Se reaction mixture or stoichiometric quantities of a Cu, In, Ga, and Se reaction mixture in a refractory crucible in such a manner that the reaction mixture is surrounded by B/sub 2/O/sub 3/, placing the thus loaded crucible in a chamber under a high pressure atmosphere of inert gas to confine the volatile Se to the crucible, and heating the reaction mixture to its melting point. The melt can then be cooled slowly to form, by direct solidification, a single crystal with enhanced structure perfection, which crystal is substantially free of fissures.

Large single crystal quaternary alloys of IB-IIIA-SE.sub.2 and methods of synthesizing the same

DOEpatents

Ciszek, Theodore F.

1988-01-01

New alloys of Cu.sub.x Ag.sub.(1-x) InSe.sub.2 (where x ranges between 0 and 1 and preferably has a value of about 0.75) and CuIn.sub.y Ga.sub.(1-y) Se.sub.2 (where y ranges between 0 and 1 and preferably has a value of about 0.90) in the form of single crystals with enhanced structure perfection, which crystals are substantially free of fissures are disclosed. Processes are disclosed for preparing the new alloys of Cu.sub.x Ag.sub.(1-x) InSe.sub.2. The process includes placing stoichiometric quantities of a Cu, Ag, In, and Se reaction mixture or stoichiometric quantities of a Cu, In, Ga, and Se reaction mixture in a refractory crucible in such a manner that the reaction mixture is surrounded by B.sub.2 O.sub.3, placing the thus loaded crucible in a chamber under a high pressure atmosphere of inert gas to confine the volatile Se to the crucible, and heating the reaction mixture to its melting point. The melt can then be cooled slowly to form, by direct solidification, a single crystal with enhanced structure perfection, which crystal is substantially free of fissures.

Development of combinations of chemically modified vegetable oils as pork backfat substitutes in sausages formulation.

PubMed

Ospina-E, Juan Camilo; Cruz-S, Adriana; Pérez-Alvarez, José Angel; Fernández-López, Juana

2010-03-01

Today's consumers look for foods which provide nutrition and pleasure, while safeguarding their health, the result of which is that they increasingly avoid foods containing cholesterol and saturated and trans fatty acids. Chemically modified vegetable oils can help tailor meat products to meet this growing need and at the same time fulfil the technological needs of the meat processing industry. In this study, 16 backfat samples were characterised for their solid fat content (SFC) and melting point and these characteristics were used to design a mixture of chemically modified vegetable oils for use as a pork fat substitute for elaborating sausages. The mixtures were prepared with different vegetable oils bearing in mind with stearic acid content due to its close correlation with the SFC. The backfat was characterised as a function of its SFC and some modified vegetable oil mixtures were proposed, which led to a 10-20% diminution in saturated fatty acids and with a melting point similar to those observed in the backfat. The fatty acid profile pointed to a polyunsaturated/saturated fatty acids ratio higher than 0.4, and an n-6/n-3 fatty acid ratio of less than 4 in both modified vegetable oil mixtures proposed. Copyright 2009 Elsevier Ltd. All rights reserved.

Atomization methods for forming magnet powders

DOEpatents

Sellers, Charles H.; Branagan, Daniel J.; Hyde, Timothy A.

2000-01-01

The invention encompasses methods of utilizing atomization, methods for forming magnet powders, methods for forming magnets, and methods for forming bonded magnets. The invention further encompasses methods for simulating atomization conditions. In one aspect, the invention includes an atomization method for forming a magnet powder comprising: a) forming a melt comprising R.sub.2.1 Q.sub.13.9 B.sub.1, Z and X, wherein R is a rare earth element; X is an element selected from the group consisting of carbon, nitrogen, oxygen and mixtures thereof; Q is an element selected from the group consisting of Fe, Co and mixtures thereof; and Z is an element selected from the group consisting of Ti, Zr, Hf and mixtures thereof; b) atomizing the melt to form generally spherical alloy powder granules having an internal structure comprising at least one of a substantially amorphous phase or a substantially nanocrystalline phase; and c) heat treating the alloy powder to increase an energy product of the alloy powder; after the heat treatment, the alloy powder comprising an energy product of at least 10 MGOe. In another aspect, the invention includes a magnet comprising R, Q, B, Z and X, wherein R is a rare earth element; X is an element selected from the group consisting of carbon, nitrogen, oxygen and mixtures thereof; Q is an element selected from the group consisting of Fe, Co and mixtures thereof; and Z is an element selected from the group consisting of Ti, Zr, Hf and mixtures thereof; the magnet comprising an internal structure comprising R.sub.2.1 Q.sub.13.9 B.sub.1.

The role of water in the petrogenesis of Marina trough magmas

NASA Astrophysics Data System (ADS)

Stolper, Edward; Newman, Sally

1994-02-01

Most variations in composition among primitive basalts from the Mariana back-arc trough can be explained by melting mixtures of an N-type mid-ocean ridge basalt (NMORB) mantle source and an H2O rich component, provided the degree of melting is positively and approximately linearly correlated with the proportion of the H2O-rich component in the mixture. We conclude that the degrees of melting by which Mariana trough magmas are generated increase from magmas similar to NMORB, through more H2O-enriched basalts, to 'arc-like' basalts, and that this increase is due to the lowering of the solidus of mantle peridotite that accompanies addition of the H2O-rich component. The H2O-rich component is likely to be ultimately derived from fluid from a subducting slab, but we propose that by the time fluids reach the source regions of Mariana trough basalts, they have interacted with sufficient mantle material that for all but the most incompatible of elements (with respect to fluid-mantle interaction), they are in equilibrium with the mantle. In contrast, fluids added to the source regions of Mariana island-arc magmas have typically interacted with less mantle and thus retain the signature of slab-derived fluids to varying degrees for all but the most compatible elements. Primitive Mariana arc basalts can be generated by melting mixtures of such incompletely exchanged slab-derived fluids and sources similar to NMORB-type mantle sources, but the degrees of melting are typically higher than those of Mariana trough NMORB and the sources have been variably depleted relative to the back-arc sources by previous melt extraction. This depletion may be related to earlier extraction of back-arc basin magmas or may evolve by repeated fluxing of the sources as fluid is continually added to them in the regions of arc magma generation. If fluid with partitioning behavior relative to the solid mantle similar to that deduced for the H2O-rich component involved in the generation of Mariana trough basalts were extracted from primitive mantle, the residual mantle would have many of the minor and trace element characteristics of typical oceanic upper mantle; primitive mantle enriched in such fluid would be a satisfactory source for the continental crust in terms of its trace and minor element chemical composition.

Characterization of Mullite-Zirconia Composite Processed by Non-Transferred and Transferred Arc Plasma

NASA Astrophysics Data System (ADS)

Yugeswaran, S.; Selvarajan, V.; Lusvarghi, L.; I. Y. Tok, A.; D. Siva Rama, Krishna

2009-04-01

The arc plasma melting technique is a simple method to synthesize high temperature reaction composites. In this study, mullite-zirconia composite was synthesized by transferred and non-transferred arc plasma melting, and the results were compared. A mixture of alumina and zircon powders with a mole ratio of 3: 2 were ball milled for four hours and melted for two minutes in the transferred and non-transferred mode of plasma arcs. Argon and air were used as plasma forming gases. The phase and microstructural formation of melted samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The microstructure of the composites was found to be affected by the mode of melting. In transferred arc melting, zirconia flowers with uniform lines along with mullite whiskers were obtained. In the case of non-transferred arc plasma melting, mullite whiskers along with star shape zirconia were formed. Differential thermal analysis (DTA) of the synthesized mullite-zirconia composites provided a deeper understanding of the mechanisms of mullite formation during the two different processes.

Crystallization of carbon-oxygen mixtures in white dwarf stars.

PubMed

Horowitz, C J; Schneider, A S; Berry, D K

2010-06-11

We determine the phase diagram for dense carbon-oxygen mixtures in white dwarf (WD) star interiors using molecular dynamics simulations involving liquid and solid phases. Our phase diagram agrees well with predictions from Ogata et al. and from Medin and Cumming and gives lower melting temperatures than Segretain et al. Observations of WD crystallization in the globular cluster NGC 6397 by Winget et al. suggest that the melting temperature of WD cores is close to that for pure carbon. If this is true, our phase diagram implies that the central oxygen abundance in these stars is less than about 60%. This constraint, along with assumptions about convection in stellar evolution models, limits the effective S factor for the 12C(α,γ)16O reaction to S(300)≤170  keV b.

Application of film-casting technique to investigate drug-polymer miscibility in solid dispersion and hot-melt extrudate.

PubMed

Parikh, Tapan; Gupta, Simerdeep Singh; Meena, Anuprabha K; Vitez, Imre; Mahajan, Nidhi; Serajuddin, Abu T M

2015-07-01

Determination of drug-polymer miscibility is critical for successful development of solid dispersions. This report details a practical method to predict miscibility and physical stability of drug with various polymers in solid dispersion and, especially, in melt extrudates by applying a film-casting technique. Mixtures of itraconazole (ITZ) with hydroxypropylmethylcellulose phthalate (HPMCP), Kollidon(®) VA 64, Eudragit(®) E PO, and Soluplus(®) were film-casted, exposed to 40°C/75% RH for 1 month and then analyzed using differential scanning calorimetry (DSC), powder X-ray diffractometry, and polarized light microscopy (PLM). ITZ had the highest miscibility with HPMCP, being miscible at drug to polymer ratio of 6:4 (w/w). There was a downward trend of lower miscibility with Soluplus(®) (miscible at 3:7, w/w, and a few microcrystals present at 4:6, w/w), Kollidon(®) VA 64 (2:8, w/w) and Eudragit(®) E PO (<1:9, w/w). PLM was found more sensitive to detect drug crystallization than DSC and powder X-ray diffractometry. There was general correlation between results of film casting and hot-melt extrusion (HME) using a twin screw extruder. For ITZ-Soluplus(®) mixtures, HME at 4:6 (w/w) resulted in a single phase, whereas drug crystallization was observed at higher drug load. HME of ITZ-Kollidon(®) VA 64 mixtures also correlated well with the miscibility predicted by film casting. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Examination of Effective Dielectric Constants Derived from Non-Spherical Melting Hydrometeor

NASA Astrophysics Data System (ADS)

Liao, L.; Meneghini, R.

2009-04-01

The bright band, a layer of enhanced radar echo associated with melting hydrometeors, is often observed in stratiform rain. Understanding the microphysical properties of melting hydrometeors and their scattering and propagation effects is of great importance in accurately estimating parameters of the precipitation from spaceborne radar and radiometers. However, one of the impediments in the study of the radar signature of the melting layer is the determination of effective dielectric constants of melting hydrometeors. Although a number of mixing formulas are available to compute the effective dielectric constants, their results vary to a great extent when water is a component of the mixture, such as in the case of melting snow. It is also physically unclear as to how to select among these various formulas. Furthermore, the question remains as to whether these mixing formulas can be applied to computations of radar polarimetric parameters from non-spherical melting particles. Recently, several approaches using numerical methods have been developed to derive the effective dielectric constants of melting hydrometeors, i.e., mixtures consisting of air, ice and water, based on more realistic melting models of particles, in which the composition of the melting hydrometeor is divided into a number of identical cells. Each of these cells is then assigned in a probabilistic way to be water, ice or air according to the distribution of fractional water contents for a particular particle. While the derived effective dielectric constants have been extensively tested at various wavelengths over a range of particle sizes, these numerical experiments have been restricted to the co-polarized scattering parameters from spherical particles. As polarimetric radar has been increasingly used in the study of microphysical properties of hydrometeors, an extension of the theory to polarimetric variables should provide additional information on melting processes. To account for polarimetric radar measurements from melting hydrometeors, it is necessary to move away from the restriction that the melting particles are spherical. In this study, our primary focus is on the derivation of the effective dielectric constants of non-spherical particles that are mixtures of ice and water. The computational model for the ice-water particle is described by a collection of 128x128x128 cubic cells of identical size. Because of the use of such a high-resolution model, the particles can be described accurately not only with regard to shape but with respect to structure as well. The Cartesian components of the mean internal electric field of particles, which are used to infer the effective dielectric constants, are calculated at each cell by the use of the Conjugate Gradient-Fast Fourier Transform (CG-FFT) numerical method. In this work we first check the validity of derived effective dielectric constant from a non-spherical mixed phase particle by comparing the polarimetric scattering parameters of an ice-water spheroid obtained from the CGFFT to those computed from the T-matrix for a homogeneous particle with the same geometry as that of the mixed phase particle (such as size, shape and orientation) and with an effective dielectric constant derived from the internal field of the mixed-phase particle. The accuracy of the effective dielectric constant can be judged by whether the scattering parameters of interest can accurately reproduce those of the exact solution, i.e., the T-matrix results. The purpose of defining an effective dielectric constant is to reduce the complexity of the scattering calculations in the sense that the effective dielectric constant, once obtained, may be applicable to a range of particle sizes, shapes and orientations. Conversely, if a different effective dielectric constant is needed for each particle size or shape, then its utility would be marginal. Having verified that the effective dielectric constant defined for a particular particle with a fixed shape, size, and orientation is valid, a check is performed to see if this effective dielectric constant can be used to characterize a class of particle types (with arbitrary sizes, shapes and orientations) if the fractional ice-water contents of melting particles remain the same. Among the scattering and polarimatric parameters used for examination of effective dielectric constant in this study, are the radar backscattering, extinction and scattering coefficients, asymmetry factor, differential reflectivity factor (ZDR), phase shift and linear polarization ratio (LDR). The goal is to determine whether the effective dielectric constant approach provides a means to compute accurately the radar polarimetric scattering parameters and radiometer brightness temperature quantities from the melting layer in a relatively simple and efficient way.

Studies of Halogen Bonding Using High-Pressure Diffractometry

DTIC Science & Technology

2007-11-08

mixed at room temperature. The 1:1 cocrystal was melted by heating it to and in the liquid form loaded to a DAC. Single-crystal of each compound or...upper edge. Figure 6. Isochoric growth of the 1,2-diiodoperfluoroethane:1,4-dioxane 1:1 cocrystal : (a) the melting process of the polycrystal...impurities in the mixture, which condensed at high pressure and grouped between the cocrystal upper face (001) and the upper culet. Figure 7. Isochoric

Phase behavior of blends of linear and branched polyethylenes in the molten and solid states by small-angle neutron scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alamo, R.G.; Mandelkern, L.; Londono, J.D.

1994-01-17

The state of mixing in blends of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) in the liquid and solid state has been examined by small-angle neutron scattering (SANS) in conjunction with deuterium labeling. In the melt, SANS results indicate that HDPE/LDPE mixtures from a single-phase solution for all concentrations, including blends containing high volume fractions ([phi] > 0.5) of branched polymer, for which multiphase melts have previously been suggested. Proper accounting for isotope effects is essential to avoid artifacts, because the H/D interaction parameter is sufficiently large ([sub [chi]HD] [approximately] 4 [times] 10[sup [minus]4]) to cause phase separation in themore » amorphous state for molecular weights (MW) >150,000. In the solid state, after slow cooling from the melt ([approximately]0.75 C/min), the HDPE/LDPE system shows extensive segregation into separate domains [approximately]100--300 [angstrom] in size. Both the shape and magnitude of the absolute scattering cross section are consistent with the conclusion that the components are extensively segregated into separate lamellae. Two-peak melting curves obtained for such mixtures support the SANS interpretation, and the segregation of components in the solid state is therefore a consequence of crystallization mechanisms rather than incompatibility in the liquid state.« less

Performance Improvement of V-Fe-Cr-Ti Solid State Hydrogen Storage Materials in Impure Hydrogen Gas.

PubMed

Ulmer, Ulrich; Oertel, Daria; Diemant, Thomas; Bonatto Minella, Christian; Bergfeldt, Thomas; Dittmeyer, Roland; Behm, R Jürgen; Fichtner, Maximilian

2018-01-17

Two approaches of engineering surface structures of V-Ti-based solid solution hydrogen storage alloys are presented, which enable improved tolerance toward gaseous oxygen (O 2 ) impurities in hydrogen (H 2 ) gas. Surface modification is achieved through engineering lanthanum (La)- or nickel (Ni)-rich surface layers with enhanced cyclic stability in an H 2 /O 2 mixture. The formation of a Ni-rich surface layer does not improve the cycling stability in H 2 /O 2 mixtures. Mischmetal (Mm, a mixture of La and Ce) agglomerates are observed within the bulk and surface of the alloy when small amounts of this material are added during arc melting synthesis. These agglomerates provide hydrogen-transparent diffusion pathways into the bulk of the V-Ti-Cr-Fe hydrogen storage alloy when the remaining oxidized surface is already nontransparent for hydrogen. Thus, the cycling stability of the alloy is improved in an O 2 -containing hydrogen environment as compared to the same alloy without addition of Mm. The obtained surface-engineered storage material still absorbs hydrogen after 20 cycles in a hydrogen-oxygen mixture, while the original material is already deactivated after 4 cycles.

Phase behaviour in complementary DNA-coated gold nanoparticles and fd-viruses mixtures: a numerical study.

PubMed

Chiappini, Massimiliano; Eiser, Erika; Sciortino, Francesco

2017-01-01

A new gel-forming colloidal system based on a binary mixture of fd-viruses and gold nanoparticles functionalized with complementary DNA single strands has been recently introduced. Upon quenching below the DNA melt temperature, such a system results in a highly porous gel state, that may be developed in a new functional material of tunable porosity. In order to shed light on the gelation mechanism, we introduce a model closely mimicking the experimental one and we explore via Monte Carlo simulations its equilibrium phase diagram. Specifically, we model the system as a binary mixture of hard rods and hard spheres mutually interacting via a short-range square-well attractive potential. In the experimental conditions, we find evidence of a phase separation occurring either via nucleation-and-growth or via spinodal decomposition. The spinodal decomposition leads to the formation of small clusters of bonded rods and spheres whose further diffusion and aggregation leads to the formation of a percolating network in the system. Our results are consistent with the hypothesis that the mixture of DNA-coated fd-viruses and gold nanoparticles undergoes a non-equilibrium gelation via an arrested spinodal decomposition mechanism.

Methods and apparatuses for making cathodes for high-temperature, rechargeable batteries

DOEpatents

Meinhardt, Kerry D; Sprenkle, Vincent L; Coffey, Gregory W

2014-05-20

The approaches for fabricating cathodes can be adapted to improve control over cathode composition and to better accommodate batteries of any shape and their assembly. For example, a first solid having an alkali metal halide, a second solid having a transition metal, and a third solid having an alkali metal aluminum halide are combined into a mixture. The mixture can be heated in a vacuum to a temperature that is greater than or equal to the melting point of the third solid. When the third solid is substantially molten liquid, the mixture is compressed into a desired cathode shape and then cooled to solidify the mixture in the desired cathode shape.

Apparatuses for making cathodes for high-temperature, rechargeable batteries

DOEpatents

Meinhardt, Kerry D.; Sprenkle, Vincent L.; Coffey, Gregory W.

2016-09-13

The approaches and apparatuses for fabricating cathodes can be adapted to improve control over cathode composition and to better accommodate batteries of any shape and their assembly. For example, a first solid having an alkali metal halide, a second solid having a transition metal, and a third solid having an alkali metal aluminum halide are combined into a mixture. The mixture can be heated in a vacuum to a temperature that is greater than or equal to the melting point of the third solid. When the third solid is substantially molten liquid, the mixture is compressed into a desired cathode shape and then cooled to solidify the mixture in the desired cathode shape.

Evidence for melt partitioning between olivine and orthopyroxene in partially molten harzburgite

NASA Astrophysics Data System (ADS)

Miller, K.; Zhu, W.; Montesi, L. G.; Le Roux, V.; Gaetani, G. A.

2013-12-01

During melting at mid-ocean ridges, melt is driven into an equilibrium, minimum-energy configuration by surface energy gradients between solid-solid and solid-liquid phase boundaries. Such a configuration, where melt is mostly restricted to three and four-grain junctions, acts as a porous medium through which melt can percolate to the surface. For a monomineralic system, melt is distributed evenly among all grains. However, in mineralogical heterogeneous systems, melt partitions unevenly between the various solid phases to minimize the total energy of the system. In a ocean ridge melting environment, where olivine is often juxtaposed against orthopyroxene (opx), lithologic partitioning is expected to turn olivine-rich regions into high-permeability conduits, through which melt can be quickly extracted, drastically increasing the permeability of the mantle [Zhu and Hirth, 2003]. Lithologic partitioning has been demonstrated in experiments using analogue systems [Watson, 1999]; however, to date, no experiment has confirmed its existence in partially molten mantle systems. We present experimental results that determine the degree of melt partitioning between olivine and opx in partially molten harzburgites. Samples were prepared from a powdered mixture of oxides and carbonates and then hot-pressed in a solid-media piston-cylinder apparatus at 1350°C and 1.5GPa [Zhu et al., 2011] to achieve an 82/18 vol. % ratio of olivine to opx. Prior to hot-pressing, basalt was added to the powdered mixtures in various proportions to test for lithologic partitioning across a range of melt fractions. Three-dimensional, 700nm-resolution images of our samples were obtained using synchrotron X-ray microtomography on the 2BM station of the Advanced Photon Source at Argonne National Labs. Image data were filtered using an anisotropic diffusion filter to enhance phase contrast and then segmented to produce binary representations of each phase. In order to quantitatively demonstrate lithologic melt partitioning in our samples, we digitally segment each grain and then fit a sample window, slightly larger than the grain, to calculate the local melt volume fraction. Our results show strong evidence for lithologic partitioning in partially molten harzburgite systems, in a ~2 to 1 ratio of local melt fraction, between olivine and opx across the range of melt fractions tested. We also present permeability, grain size, and connectivity analyses of our samples in order to evaluate the effects of melt partitioning on melt migration rates at mid-ocean ridges, as well as at other locations in the Earth where partial melting occurs. References Watson, E. B. (1999), Lithologic partitioning of fluids and melts, American Minerologist, 84, 1693-1710. Zhu, W., and G. Hirth (2003), A network model for permeability in partially molten rocks, Earth Planet. Sci. Lett., 212(3-4), 407-416, doi:10.1016/S0012-821X(03)00264-4. Zhu, W., G. A. Gaetani, F. Fusseis, L. G. J. Montési, and F. De Carlo (2011), Microtomography of partially molten rocks: three-dimensional melt distribution in mantle peridotite, Science, 332(6025), 88-91, doi:10.1126/science.1202221.

Phase relations in the Fe-FeSi system at high pressures and temperatures

NASA Astrophysics Data System (ADS)

Fischer, Rebecca A.; Campbell, Andrew J.; Reaman, Daniel M.; Miller, Noah A.; Heinz, Dion L.; Dera, Przymyslaw; Prakapenka, Vitali B.

2013-07-01

The Earth's core is comprised mostly of iron and nickel, but it also contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is important to understand the high pressure, high temperature properties and behavior of alloys in the Fe-FeSi system, such as their phase diagrams. We determined melting temperatures and subsolidus phase relations of Fe-9 wt% Si and stoichiometric FeSi using synchrotron X-ray diffraction at high pressures and temperatures, up to ~200 GPa and ~145 GPa, respectively. Combining this data with that of previous studies, we generated phase diagrams in pressure-temperature, temperature-composition, and pressure-composition space. We find the B2 crystal structure in Fe-9Si where previous studies reported the less ordered bcc structure, and a shallower slope for the hcp+B2 to fcc+B2 boundary than previously reported. In stoichiometric FeSi, we report a wide B2+B20 two-phase field, with complete conversion to the B2 structure at ~42 GPa. The minimum temperature of an Fe-Si outer core is 4380 K, based on the eutectic melting point of Fe-9Si, and silicon is shown to be less efficient at depressing the melting point of iron at core conditions than oxygen or sulfur. At the highest pressures reached, only the hcp and B2 structures are seen in the Fe-FeSi system. We predict that alloys containing more than ~4-8 wt% silicon will convert to an hcp+B2 mixture and later to the hcp structure with increasing pressure, and that an iron-silicon alloy in the Earth's inner core would most likely be a mixture of hcp and B2 phases.

Investigation of Biodiesel Through Photopyroelectric and Dielectric-Constant Measurements as a Function of Temperature: Freezing/Melting Interval

NASA Astrophysics Data System (ADS)

Zanelato, E. B.; Machado, F. A. L.; Rangel, A. B.; Guimarães, A. O.; Vargas, H.; da Silva, E. C.; Mansanares, A. M.

2015-06-01

Biodiesel is a promising option for alternative fuels since it derives from natural and renewable materials; it is biodegradable and less polluting than fossil fuels. A gradual replacement of diesel by biodiesel has been adopted by many countries, making necessary the investigation of the physical properties of biodiesel and of its mixture in diesel. Photothermal techniques, specifically the photopyroelectric technique (PPE), have proved to be suitable in the characterization of biodiesel and of its precursor oils, as well as of the biodiesel/diesel mixtures. In this paper, we investigate thermal and electrical properties of animal fat-based biodiesel as a function of temperature, aiming to characterize the freezing/melting interval and the changes in the physical properties from the solid to the liquid phase. The samples were prepared using the transesterification method, by the ethylic route. Optical transmittance experiments were carried out in order to confirm the phase transition interval. Solid and liquid phases present distinct thermal diffusivities and conductivities, as well as dielectric constants. The PPE signal amplitude is governed by the changes in the thermal diffusivity/conductivity. As a consequence, the amplitude of the signal becomes like a step function, which is smoothed and sometimes delayed by the nucleation processes during cooling. A similar behavior is found in the dielectric constant data, which is higher in the liquid phase since the molecules have a higher degree of freedom. Both methods (PPE/dielectric constant) proved to be useful in the characterization of the freezing/melting interval, as well as to establish the distinction in the physical properties of solid and liquid phases. The methodology allowed a discussion of the cloud point and the pour point of the samples in the temperature variation interval.

Phase relations in the Fe-FeSi system at high pressures and temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fischer, Rebecca A.; Campbell, Andrew J.; Reaman, Daniel M.

2016-07-29

The Earth's core is comprised mostly of iron and nickel, but it also contains several weight percent of one or more unknown light elements, which may include silicon. Therefore it is important to understand the high pressure, high temperature properties and behavior of alloys in the Fe–FeSi system, such as their phase diagrams. We determined melting temperatures and subsolidus phase relations of Fe–9 wt% Si and stoichiometric FeSi using synchrotron X-ray diffraction at high pressures and temperatures, up to ~200 GPa and ~145 GPa, respectively. Combining this data with that of previous studies, we generated phase diagrams in pressure–temperature, temperature–composition,more » and pressure–composition space. We find the B2 crystal structure in Fe–9Si where previous studies reported the less ordered bcc structure, and a shallower slope for the hcp+B2 to fcc+B2 boundary than previously reported. In stoichiometric FeSi, we report a wide B2+B20 two-phase field, with complete conversion to the B2 structure at ~42 GPa. The minimum temperature of an Fe–Si outer core is 4380 K, based on the eutectic melting point of Fe–9Si, and silicon is shown to be less efficient at depressing the melting point of iron at core conditions than oxygen or sulfur. At the highest pressures reached, only the hcp and B2 structures are seen in the Fe–FeSi system. We predict that alloys containing more than ~4–8 wt% silicon will convert to an hcp+B2 mixture and later to the hcp structure with increasing pressure, and that an iron–silicon alloy in the Earth's inner core would most likely be a mixture of hcp and B2 phases.« less

Experiments on water/melt explosions, nature of products, and models of dispersal

NASA Technical Reports Server (NTRS)

Sheridan, M. F.; Wohletz, K. H.

1984-01-01

Experiments were carried out in a steel pressure device using controlled amounts of water and thermite melt to examine the mechanical energy released on explosive mixing following the initial contact of the two materials. An experimental design was used to allow the direct calculation of the mechanical energy by the dynamic lift of the device as recorded both optically and physically. A large number of experiments were run to accurately determine the optimum mixture of water and melt for the conversion of thermal to mechanical energy. The maximum efficiency observed was about 12% at a water/thermite mass ratio of 0.50. These experiments are the basis for the development of models of hydroexplosions and melt fragmentation. Particles collected from the experimental products are similar in size and shape to pyroclasts produced by much larger hydrovolcanic explosions. Melt rupture at optimum ratios produces very fine particles whereas rupture at high or low water/melt ratios produces large melt fragments. Grain surface textures in the experimental products are also related to the water/melt ratio and the mechanism of explosive mixing. It is thus possible to have qualitative information about the nature of the explosion from the sizes and shapes of the fragments produced.

Electrical conductivity of basaltic and carbonatite melt-bearing peridotites at high pressures: Implications for melt distribution and melt fraction in the upper mantle

NASA Astrophysics Data System (ADS)

Yoshino, Takashi; Laumonier, Mickael; McIsaac, Elizabeth; Katsura, Tomoo

2010-07-01

Electrical impedance measurements were performed on two types of partial molten samples with basaltic and carbonatitic melts in a Kawai-type multi-anvil apparatus in order to investigate melt fraction-conductivity relationships and melt distribution of the partial molten mantle peridotite under high pressure. The silicate samples were composed of San Carlos olivine with various amounts of mid-ocean ridge basalt (MORB), and the carbonate samples were a mixture of San Carlos olivine with various amounts of carbonatite. High-pressure experiments on the silicate and carbonate systems were performed up to 1600 K at 1.5 GPa and up to at least 1650 K at 3 GPa, respectively. The sample conductivity increased with increasing melt fraction. Carbonatite-bearing samples show approximately one order of magnitude higher conductivity than basalt-bearing ones at the similar melt fraction. A linear relationship between log conductivity ( σbulk) and log melt fraction ( ϕ) can be expressed well by the Archie's law (Archie, 1942) ( σbulk/ σmelt = Cϕn) with parameters C = 0.68 and 0.97, n = 0.87 and 1.13 for silicate and carbonate systems, respectively. Comparison of the electrical conductivity data with theoretical predictions for melt distribution indicates that the model assuming that the grain boundary is completely wetted by melt is the most preferable melt geometry. The gradual change of conductivity with melt fraction suggests no permeability jump due to melt percolation at a certain melt fraction. The melt fraction of the partial molten region in the upper mantle can be estimated to be 1-3% and ˜ 0.3% for basaltic melt and carbonatite melt, respectively.

Applications of Laser Cladded WC-Based Wear Resistant Coatings

NASA Astrophysics Data System (ADS)

Verwimp, Jo; Rombouts, Marleen; Geerinckx, Eric; Motmans, Filip

Laser cladding is an additive process wherein a laser source is used to melt metal-based powder or wire on to a metal substrate. The technique is frequently used to produce wear resistant coatings consisting of a metal matrix and a ceramic strengthening phase. In this study mixtures of nickel based powders and various amounts of tungsten carbides have been used as feedstock for laser cladding on a range of steel substrates and for different applications. Crack-free low porosity coatings with a thickness of about 1 mm and carbide concentrations up to 50 vol% have been produced. The evaluation of the wear resistance of the different coatings is performed on lab scale or in the application itself.

Internal zone growth method for producing metal oxide metal eutectic composites

DOEpatents

Clark, Grady W.; Holder, John D.; Pasto, Arvid E.

1980-01-01

An improved method for preparing a cermet comprises preparing a compact having about 85 to 95 percent theoretical density from a mixture of metal and metal oxide powders from a system containing a eutectic composition, and inductively heating the compact in a radiofrequency field to cause the formation of an internal molten zone. The metal oxide particles in the powder mixture are effectively sized relative to the metal particles to permit direct inductive heating of the compact by radiofrequency from room temperature. Surface melting is prevented by external cooling or by effectively sizing the particles in the powder mixture.

Formation of titanium diboride coatings during the anodic polarization of titanium in a chloride melt with a low boron oxide content

NASA Astrophysics Data System (ADS)

Elshina, L. A.; Malkov, V. B.; Molchanova, N. G.

2015-02-01

The corrosion-electrochemical behavior of titanium in a molten eutectic mixture of cesium and sodium chlorides containing up to 1 wt % boron oxide is studied in the temperature range 810-870 K in an argon atmosphere. The potential, the current, and the rate of titanium corrosion are determined. The optimum conditions of forming a dense continuous titanium diboride coating on titanium with high adhesion to the metallic base are found for the anodic activation of titanium in the molten electrolyte under study.

An obstacle in preparing alloisoleucine.

PubMed

Laird, W M; Matai, S; Synge, R L

1970-03-01

Alloisoleucine, prepared from a mixture of racemic isoleucine-alloisoleucine diastereoisomers, can be heavily contaminated with isoleucine if the recrystallization of acetyl-dl-alloisoleucine is controlled by melting point only. Two commercial specimens were found to be thus contaminated.

Enhanced performance and interfacial investigation of mineral-based composite phase change materials for thermal energy storage

PubMed Central

Li, Chuanchang; Fu, Liangjie; Ouyang, Jing; Yang, Huaming

2013-01-01

A novel mineral-based composite phase change materials (PCMs) was prepared via vacuum impregnation method assisted with microwave-acid treatment of the graphite (G) and bentonite (B) mixture. Graphite and microwave-acid treated bentonite mixture (GBm) had more loading capacity and higher crystallinity of stearic acid (SA) in the SA/GBm composite. The SA/GBm composite showed an enhanced thermal storage capacity, latent heats for melting and freezing (84.64 and 84.14 J/g) was higher than those of SA/B sample (48.43 and 47.13 J/g, respectively). Addition of graphite was beneficial to the enhancement in thermal conductivity of the SA/GBm composite, which could reach 0.77 W/m K, 31% higher than SA/B and 196% than pure SA. Furthermore, atomic-level interfaces between SA and support surfaces were depicted, and the mechanism of enhanced thermal storage properties was in detail investigated. PMID:23712069

Electrical Conductivities of Low-Temperature KCl-ZrCl4 and CsCl-ZrCl4 Molten Mixtures

NASA Astrophysics Data System (ADS)

Salyulev, Alexander B.; Potapov, Alexei M.

2018-02-01

The electrical conductivities of molten KCl-ZrCl4 and CsCl-ZrCl4 mixtures, including their heterogeneous (melt+crystals) ranges, were measured for the first time. The concentration ranges were 65-72 and 66-75 mol.% of ZrCl4, and the temperature ranges were 482-711 and 548-735 K, respectively. The measurements were carried out in cells of an original design.

Equation of state of silicate liquids

NASA Astrophysics Data System (ADS)

Jing, Zhicheng

Equation of state of silicate liquids is crucial to our understanding of melting processes such as the generation and differentiation of silicate melts in Earth and hence to explore the geophysical and geochemical consequences of melting. A comparison of compressional properties reveals fundamental differences in compressional mechanisms between silicate liquids and solids. Due to a liquid's ability to change structures, the compression of liquids is largely controlled by the entropic contribution to the free energy in addition to the internal energy contribution that is available to solids. In order to account for the entropic contribution, a new equation of state of silicate liquids is proposed based on the theory of hard-sphere mixtures. The equation of state is calibrated for SiO2-Al 2O3-FeO-MgO-CaO liquids and other systems. The new equation of state provides a unified explanation for the experimental observations on compressional properties of liquids including the bulk moduli of silicate liquids as well as the pressure dependence of Gruneisen parameter. The effect of chemical composition on melt density can be studied by the equation of state. Results show that FeO and H2O are the most important components in melts that control the melt density at high pressure due to their very different mean atomic masses from other melt components. Adding SiO2 can make a melt more compressible at high pressure due to its continuous change of coordination from 4-fold to 6-fold. The effect of 1-120 on melt density is further investigated by high-pressure experiments at the conditions of 9 to 15 GPa (corresponding to the depths of 300-500 km in the Earth) and 1900 °C to 2200 °C. The density of three dry melts and four hydrous melts with 2-7 wt% H2O was determined. Density data are analyzed by both the Birch-Mumaghan equation of state and the hard sphere equation of state. The partial molar volume of H2O is determined to be 8.8 cm3/mol at 14 GPa and 2173 K. The hypothesis that silicate melts can be gravitationally stable atop the 410 km discontinuity is tested. Results show that the conditions for density crossovers between melts and the upper mantle materials at the bottom of the upper mantle are marginally satisfied.

The Effect of CO2 on Partial Reactive Crystallization of MORB-Eclogite-derived Basaltic Andesite in Peridotite and Generation of Silica-Undersaturated Basalts

NASA Astrophysics Data System (ADS)

Mallik, A.; Dasgupta, R.

2012-12-01

Recycled oceanic crust (MORB-eclogite) is considered to be the dominant heterogeneity in Earth's mantle. Because MORB-eclogite is more fusible than peridotite, siliceous partial melt derived from it must react with peridotite while the latter is still in the subsolidus state. Thus, studying such reactive process is important in understanding melting dynamics of the Earth's mantle. Reaction of MORB-eclogite-derived andesitic partial melt with peridotite can produce alkalic melts by partial reactive crystallization but these melts are not as silica-undersaturated as many natural basanites, nephelinites or melititites [1]. In this study, we constrain how dissolved CO2 in a siliceous MORB-eclogite-derived partial melt affects the reaction phase equilibria involving peridotite and can produce nephelinitic melts. Here we compare experiments on CO2-free [1] and 2.6 wt.% CO2 bearing andesitic melt+lherzolite mixtures conducted at 1375 °C and 3 GPa with added melt fraction of 8-50 wt.%. In both CO2-free and CO2-bearing experiments, melt and olivine are consumed and opx and garnet are produced, with the extent of modal change for a given melt-rock ratio being greater for the CO2-bearing experiments. While the residue evolves to a garnet websterite by adding 40% of CO2-bearing melt, the residue becomes olivine-free by adding 50% of the CO2-free melt. Opx mode increases from 12 to ~55 wt.% for 0 to 40% melt addition in CO2-bearing system and 12 to ~43 wt.% for 0 to 50% melt addition in CO2-free system. Garnet mode, for a similar range of melt-rock ratio, increases from ~10 to ~15 wt.% for CO2 bearing system and to ~11 wt.% for CO2-free system. Reacted melts from 25-33% of CO2-bearing melt-added runs contain ~39 wt.% SiO2 , ~11-13 wt.% TiO2, ~9 wt.% Al2O3, ~11 wt.% FeO*, 16 wt.% MgO, 10-11 wt.% CaO, and 3 wt.% Na2O whereas experiments with a similar melt-rock ratio in a CO2-free system yield melts with 44-45 wt.% SiO2, 6-7 wt.% TiO2, 13-14 wt.% Al2O3, 10-11 wt.% FeO*, 12-13 wt.% MgO, ~8 wt.% CaO, and ~4 wt.% Na2O. Our study shows that with only 2.6 wt.% CO2, andesites, owing to partial reactive crystallization in a peridotite matrix, can evolve to nephelinites (as opposed to basanites for CO2-free runs) that match with silica-undersaturated oceanic basalts better than reacted melts from CO2-free conditions. The effects of CO2 on the partial reactive crystallization of andesite in a fertile peridotite matrix thus are: a) lowered melt- SiO2 owing to increased stability of opx at the liquidus of basalt, b) lowered Al2O3 content of basalts owing to increased crystallization of garnet. Experiments with 1 and 5 wt.% CO2-bearing andesite-peridotite mixture are underway and will be presented. [1] Mallik and Dasgupta (2012), EPSL, 329-330, 97-108.

Structure and Energetics of Clusters Relevant to Thorium Tetrachloride Melts

NASA Astrophysics Data System (ADS)

Akdeniz, Z.; Tosi, M. P.

2000-10-01

We study within an ionic model the structure and energetics of neutral and charged molecular clusters which may be relevant to molten ThCl4 and to its liquid mixtures with alkali chlorides, with reference to Raman scattering experiments by Photiadis and Papatheodorou. As stressed by these authors, the most striking facts for ThCl4 in comparison to other tetrachloride compounds (and in particular to ZrCl4) are the appreciable ionic conductivity of the pure melt and the continuous structural changes which occur in the melt mixtures with varying composition. After adjusting our model to data on the isolated ThCl4 tetrahedral molecule, we evaluate (i) the Th2Cl8 dimer and the singly charged species obtained from it by chlorine-ion transfer between two such neutral dimers; (ii) the ThCl6 and ThCl7 clusters both as charged anions and as alkali-compensated species; and (iii) various oligomers carrying positive or negative double charges. Our study shows that the characteristic structural properties of the ThCl4 compound and of the alkali-Th chloride systems are the consequence of the relatively high ionic character of the binding, which is already evident in the isolated ThCl4 monomer.

NON-AQUEOUS DISSOLUTION OF MASSIVE PLUTONIUM

DOEpatents

Reavis, J.G.; Leary, J.A.; Walsh, K.A.

1959-05-12

A method is presented for obtaining non-aqueous solutions or plutonium from massive forms of the metal. In the present invention massive plutonium is added to a salt melt consisting of 10 to 40 weight per cent of sodium chloride and the balance zinc chloride. The plutonium reacts at about 800 deg C with the zinc chloride to form a salt bath of plutonium trichloride, sodium chloride, and metallic zinc. The zinc is separated from the salt melt by forcing the molten mixture through a Pyrex filter.

Containerless synthesis of amorphous and nanophase organic materials

DOEpatents

Benmore, Chris J.; Weber, Johann R.

2016-05-03

The invention provides a method for producing a mixture of amorphous compounds, the method comprising supplying a solution containing the compounds; and allowing at least a portion of the solvent of the solution to evaporate while preventing the solute of the solution from contacting a nucleation point. Also provided is a method for transforming solids to amorphous material, the method comprising heating the solids in an environment to form a melt, wherein the environment contains no nucleation points; and cooling the melt in the environment.

Low-melting point inorganic nitrate salt heat transfer fluid

DOEpatents

Bradshaw, Robert W [Livermore, CA; Brosseau, Douglas A [Albuquerque, NM

2009-09-15

A low-melting point, heat transfer fluid made of a mixture of four inorganic nitrate salts: 9-18 wt % NaNO.sub.3, 40-52 wt % KNO.sub.3, 13-21 wt % LiNO.sub.3, and 20-27 wt % Ca(NO.sub.3).sub.2. These compositions can have liquidus temperatures less than 100 C; thermal stability limits greater than 500 C; and viscosity in the range of 5-6 cP at 300 C; and 2-3 cP at 400 C.

Thermodynamic study of (anthracene + benzo[a]pyrene) solid mixtures

PubMed Central

Rice, James W.; Suuberg, Eric M.

2010-01-01

To characterize better the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the {anthracene (1) + benzo[a]pyrene (2)} system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at x1 = 0.26. The eutectic mixture is an amorphous solid that lacks organized crystal structure and melts between T = (414 and 420) K. For mixtures that contain 0.10 < x1 < 0.90, the enthalpy of fusion is dominated by that of the eutectic. Solid-vapor equilibrium studies show that mixtures of anthracene and benzo[a]pyrene at x1 < 0.10 sublime at the vapor pressure of pure benzo[a]pyrene. These results suggest that the solid-vapor equilibrium of benzo[a]pyrene is not significantly influenced by moderate levels of anthracene in the crystal structure. PMID:20814451

Shock Reactivity of Non-Porous Mixtures of Manganese and Sulfur

NASA Astrophysics Data System (ADS)

Jetté, F. X.; Goroshin, S.; Higgins, A. J.

2007-12-01

Equimolar mixtures of manganese powder and sulfur were melt-cast into solid pellets in order to study the mechanism of shock-enhanced reactivity in non-porous heterogeneous mixtures. This mixture was selected due to the large exothermic heat release of the manganese-sulfur reaction (214 kJ/mol), which causes the reaction to be self-sustaining once initiated. The test samples were placed in planar recovery ampoules and a strong shock was delivered via the detonation of a charge of amine-sensitized nitromethane. Various shock strengths were achieved by placing different thicknesses of PMMA attenuator discs between the explosive charge and the ampoule. The results confirmed that shock-induced reactions can be produced in highly non-porous mixtures. Indeed, the critical shock pressure that caused ignition of the mixture in the ampoule was found to be in the range 2.2-3.0 GPa (pressures were estimated using LS-DYNA simulations of samples with 100% TMD).

Evidence for Impact Shock Melting in CM and CI Chondrite Regolith Samples

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Le, Loan

2014-01-01

C class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed carbonaceous chondrites, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be near-Earth asteroid 1999 JU3, the target of the Hayabusa II sample return mission [1], although not all spectra indicate this. In fact most spectra of 1999 JU3 are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C class asteroids - impact shock melting. Impact shock melting has been proposed to explain some mineralogical characteristics of CB chondrites, but has not been considered a major process for hydrous carbonaceous chondrites. What evidence is there for significant shock melting in the very abundant CMs, or less abundant but still important CI chondrites?

Effect of Halide Flux on Physicochemical Properties of MgCl2-Based Molten Salts for Accelerating Zirconium Production: Thermodynamic Assessment

NASA Astrophysics Data System (ADS)

Shin, Jae Hong; Park, Joo Hyun

2016-09-01

The effective halide flux additive for increasing the density of MgCl2 mixture and for decreasing the activity of MgCl2 was investigated in order to improve the reaction efficiency between gaseous ZrCl4 and fresh Mg melt to produce zirconium sponge. Thermochemical computation using FactSageTM software was primarily carried out, followed by the experimental confirmation. The addition of CaCl2, BaCl2, MgF2, and CaF2 to the molten MgCl2 increases the density of the melts, indicating that these halide additives can be a candidate to increase the density of the MgCl2-based molten salts. Among them, BaCl2, MgF2, and CaF2 are the useful additives. The activity of MgCl2 can be reduced by the addition of BaCl2, KCl, NaCl, MgF2, and CaF2, among which the CaF2 is the most effective additive to reduce the activity of MgCl2 with the strongest negative deviation from an ideality. Thus, the addition of CaF2 to the MgCl2, forming the MgCl2-CaF2 binary melt, is the most effective way not only to increase the density of the melt but also to decrease the activity of MgCl2, which was experimentally confirmed. Consequently, the production rate of zirconium sponge by magnesiothermic reduction process can be accelerated by the addition of CaF2.

Melting relations in the Fe-rich portion of the system FeFeS at 30 kb pressure

USGS Publications Warehouse

Brett, R.; Bell, P.M.

1969-01-01

The melting relations of FeFeS mixtures covering the composition range from Fe to Fe67S33 have been determined at 30 kb pressure. The phase relations are similar to those at low pressure. The eutectic has a composition of Fe72.9S27.1 and a temperature of 990??C. Solubility of S in Fe at elevated temperatures at 30 kb is of the same order of magnitude as at low pressure. Sulfur may have significantly lowered the melting point of iron in the upper mantle during the period of coalescence of metal prior to core formation in the primitive earth. ?? 1969.

TEMperature Pressure ESTimation of a homogeneous boiling fuel-steel mixture in an LMFBR core. [TEMPEST code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pyun, J.J.; Majumdar, D.

The paper describes TEMPEST, a simple computer program for the temperature and pressure estimation of a boiling fuel-steel pool in an LMFBR core. The time scale of interest of this program is large, of the order of ten seconds. Further, the vigorous boiling in the pool will generate a large contact, and hence a large heat transfer between fuel and steel. The pool is assumed to be a uniform mixture of fuel and steel, and consequently vapor production is also assumed to be uniform throughout the pool. The pool is allowed to expand in volume if there is steel meltingmore » at the walls. In this program, the total mass of liquid and vapor fuel is always kept constant, but the total steel mass in the pool may change by steel wall melting. Because of a lack of clear understanding of the physical phenomena associated with the progression of a fuel-steel mixture at high temperature, various input options have been built-in to enable one to perform parametric studies. For example, the heat transfer from the pool to the surrounding steel structure may be controlled by input values for the heat transfer coefficients, or, the heat transfer may be calculated by a correlation obtained from the literature. Similarly, condensation of vapor on the top wall can be specified by input values of the condensation coefficient; the program can otherwise calculate condensation according to the non-equilibrium model predictions. Meltthrough rates of the surrounding steel walls can be specified by a fixed melt-rate or can be determined by a fraction of the heat loss that goes to steel-melting. The melted steel is raised to the pool temperature before it is joined with the pool material. Several applications of this program to various fuel-steel pools in the FFTF and the CRBR cores are discussed.« less

Deep eutectic solvents: similia similibus solvuntur?

PubMed

Zahn, Stefan

2017-02-01

Deep eutectic solvents, mixtures of an organic compound and a salt with a deep eutectic melting point, are promising cheap and eco-friendly alternatives to ionic liquids. Ab initio molecular dynamics simulations of reline, a mixture consisting of urea and choline chloride, reveal that not solely hydrogen bonds allow similar interactions between both constituents. The chloride anion and the oxygen atom of urea also show a similar spatial distribution close to the cationic core of choline due to a similar charge located on both atoms. As a result of multiple similar interactions, clusters migrating together cannot be observed in reline which supports the hypothesis similia similibus solvuntur. In contrast to previous suggestions, the interaction of the hydroxyl group of choline with a hydrogen bond acceptor is overall rigid. Fast hydrogen bond acceptor dynamics is facilitated by the hydrogen atoms in the trans position to the carbonyl group of urea which contributes to the low melting point of reline.

Microgravity

NASA Image and Video Library

2004-04-15

Researchers have found that as melted metals and alloys (combinations of metals) solidify, they can form with different arrangements of atoms, called microstructures. These microstructures depend on the shape of the interface (boundary) between the melted metal and the solid crystal it is forming. There are generally three shapes that the interface can take: planar, or flat; cellular, which looks like the cells of a beehive; and dendritic, which resembles tiny fir trees. Convection at this interface can affect the interface shape and hide the other phenomena (physical events). To reduce the effects of convection, researchers conduct experiments that examine and control conditions at the interface in microgravity. Microgravity also helps in the study of alloys composed of two metals that do not mix. On Earth, the liquid mixtures of these alloys settle into different layers due to gravity. In microgravity, the liquid metals do not settle, and a solid more uniform mixture of both metals can be formed.

Production of iron from metallurgical waste

DOEpatents

Hendrickson, David W; Iwasaki, Iwao

2013-09-17

A method of recovering metallic iron from iron-bearing metallurgical waste in steelmaking comprising steps of providing an iron-bearing metallurgical waste containing more than 55% by weight FeO and FeO equivalent and a particle size of at least 80% less than 10 mesh, mixing the iron-bearing metallurgical waste with a carbonaceous material to form a reducible mixture where the carbonaceous material is between 80 and 110% of the stoichiometric amount needed to reduce the iron-bearing waste to metallic iron, and as needed additions to provide a silica content between 0.8 and 8% by weight and a ratio of CaO/SiO.sub.2 between 1.4 and 1.8, forming agglomerates of the reducible mixture over a hearth material layer to protect the hearth, heating the agglomerates to a higher temperature above the melting point of iron to form nodules of metallic iron and slag material from the agglomerates by melting.

High Temperature Transfer Molding Resins

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); Smith, Joseph G., Jr. (Inventor); Hergenrother, Paul M. (Inventor)

2000-01-01

High temperature resins containing phenylethynyl groups that are processable by transfer molding have been prepared. These phenylethynyl containing oligomers were prepared from aromatic diamines containing phenylethynyl groups and various ratios of phthalic anhydride and 4-phenylethynlphthalic anhydride in glacial acetic acid to form a mixture of imide compounds in one step. This synthetic approach is advantageous since the products are a mixture of compounds and consequently exhibit a relatively low melting temperature. In addition, these materials exhibit low melt viscosities which are stable for several hours at 210-275 C, and since the thermal reaction of the phenylethynyl group does not occur to any appreciable extent at temperatures below 300 C, these materials have a broad processing window. Upon thermal cure at approximately 300-350 C, the phenylethynyl groups react to provide a crosslinked resin system. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

Phase Change Energy Storage Material Suitable for Solar Heating System

NASA Astrophysics Data System (ADS)

Li, Xiaohui; Li, Haihua; Zhang, Lihui; Liu, Zhenfa

2018-01-01

Differential scanning calorimetry (DSC) was used to investigate the thermal properties of palmitic acid, myristic acid, laurel acid and the binary composite of palmitic/laurel acid and palmitic/myristic acid. The results showed that the phase transition temperatures of the three monomers were between 46.9-65.9°C, and the latent heats were above 190 J/g, which could be used as solar energy storage material. When the mass ratio of Palmitic acid and myristic was 1:1, the eutectic mixture could be formed. The latent heat of the eutectic mixture was 186.6 J/g, the melting temperature and the solidification temperature was 50.6°C and 43.8°C respectively. The latent heat of phase change and the melting temperature had not obvious variations after 400 thermal cycles, which proved that the binary composite had good thermal stability and was suitable for solar floor radiant heating system.

A Physical Model for Three-Phase Compaction in Silicic Magma Reservoirs

NASA Astrophysics Data System (ADS)

Huber, Christian; Parmigiani, Andrea

2018-04-01

We develop a model for phase separation in magma reservoirs containing a mixture of silicate melt, crystals, and fluids (exsolved volatiles). The interplay between the three phases controls the dynamics of phase separation and consequently the chemical and physical evolution of magma reservoirs. The model we propose is based on the two-phase damage theory approach of Bercovici et al. (2001, https://doi.org/10.1029/2000JB900430) and Bercovici and Ricard (2003, https://doi.org/10.1046/j.1365-246X.2003.01854.x) because it offers the leverage of considering interface (in the macroscopic limit) between phases that can deform depending on the mechanical work and phase changes taking place locally in the magma. Damage models also offer the advantage that pressure is defined uniquely to each phase and does not need to be equal among phases, which will enable us to consider, in future studies, the large capillary pressure at which fluids are mobilized in mature, crystal-rich, magma bodies. In this first analysis of three-phase compaction, we solve the three-phase compaction equations numerically for a simple 1-D problem where we focus on the effect of fluids on the efficiency of melt-crystal separation considering the competition between viscous and buoyancy stresses only. We contrast three sets of simulations to explore the behavior of three-phase compaction, a melt-crystal reference compaction scenario (two-phase compaction), a three-phase scenario without phase changes, and finally a three-phase scenario with a parameterized second boiling (crystallization-induced exsolution). The simulations show a dramatic difference between two-phase (melt crystals) and three-phase (melt-crystals-exsolved volatiles) compaction-driven phase separation. We find that the presence of a lighter, significantly less viscous fluid hinders melt-crystal separation.

Effects of water, depth and temperature on partial melting of mantle-wedge fluxed by hydrous sediment-melt in subduction zones

NASA Astrophysics Data System (ADS)

Mallik, Ananya; Dasgupta, Rajdeep; Tsuno, Kyusei; Nelson, Jared

2016-12-01

This study investigates the partial melting of variable bulk H2O-bearing parcels of mantle-wedge hybridized by partial melt derived from subducted metapelites, at pressure-temperature (P-T) conditions applicable to the hotter core of the mantle beneath volcanic arcs. Experiments are performed on mixtures of 25% sediment-melt and 75% fertile peridotite, from 1200 to 1300 °C, at 2 and 3 GPa, with bulk H2O concentrations of 4 and 6 wt.%. Combining the results from these experiments with previous experiments containing 2 wt.% bulk H2O (Mallik et al., 2015), it is observed that all melt compositions, except those produced in the lowest bulk H2O experiments at 3 GPa, are saturated with olivine and orthopyroxene. Also, higher bulk H2O concentration increases melt fraction at the same P-T condition, and causes exhaustion of garnet, phlogopite and clinopyroxene at lower temperatures, for a given pressure. The activity coefficient of silica (ϒSiO2) for olivine-orthopyroxene saturated melt compositions (where the activity of silica, aSiO2 , is buffered by the reaction olivine + SiO2 = orthopyroxene) from this study and from mantle melting studies in the literature are calculated. In melt compositions generated at 2 GPa or shallower, with increasing H2O concentration, ϒSiO2 increases from <1 to ∼1, indicating a transition from non-ideal mixing as OH- in the melt (ϒSiO2 <1) to ideal mixing as molecular H2O (ϒSiO2 ∼1). At pressures >2 GPa, ϒSiO2 >1 at higher H2O concentrations in the melt, indicate requirement of excess energy to incorporate molecular H2O in the silicate melt structure, along with a preference for bridging species and polyhedral edge decorations. With vapor saturation in the presence of melt, ϒSiO2 decreases indicating approach towards ideal mixing of H2O in silicate melt. For similar H2O concentrations in the melt, ϒSiO2 for olivine-orthopyroxene saturated melts at 3 GPa is higher than melts at 2 GPa or shallower. This results in melts generated at 3 GPa being more silica-poor than melts at 2 GPa. Thus, variable bulk H2O and pressure of melt generation results in the partial melts from this study varying in composition from phonotephrite to basaltic andesite at 2 GPa and foidite/phonotephrite to basalt at 3 GPa, forming a spectrum of arc magmas. Modeling suggests that the trace element patterns of sediment-melt are unaffected by the process of hybridization within the hotter core of the mantle-wedge. K2O/H2O and H2O/Ce ratios of the sediment-melts are unaffected, within error, by the process of hybridization of the mantle-wedge. This implies that thermometers based on K2O/H2O and H2O/Ce ratios of arc lavas may be used to estimate slab-top temperatures when (a) sediment-melt from the slab reaches the hotter core of the mantle-wedge by focused flow (b) sediment-melt freezes in the overlying mantle at the slab-mantle interface and the hybridized package rises as a mélange diapir and partially melts at the hotter core of the mantle-wedge. Based on the results from this study and previous studies, both channelized and porous flow of sediment-melt/fluid through the sub-arc mantle can explain geochemical signatures of arc lavas under specific geodynamic scenarios of fluid/melt fluxing, hybridization, and subsequent mantle melting.

Lipid melting and cuticular permeability: new insights into an old problem.

PubMed

Gibbs, Allen G.

2002-04-01

The idea that the physical properties of cuticular lipids affect cuticular permeability goes back over 65 years. This proposal has achieved textbook status, despite controversy and the general lack of direct supporting evidence. Recent work supports the standard model, in which lipid melting results in increased cuticular permeability. Surprisingly, although all species studied to date can synthesize lipids that remain in a solid state at environmental temperatures, partial melting often occurs due to the deposition of lipids with low melting points. This will tend to increase water loss; the benefits may include better dispersal of lipids or other compounds across the cuticle or improved communication via cuticular pheromones. In addition, insects with high melting-point lipids are not necessarily less permeable at low temperatures. One likely reason is variation in lipid properties within the cuticle. Surface lipids differ from one region to another, and biophysical studies of model mixtures suggest the occurrence of phase separation between melted and solid lipid fractions. Lipid phase separation may have important implications for insect water balance and chemical communication.

The Denaturation Transition of DNA in Mixed Solvents

PubMed Central

Hammouda, Boualem; Worcester, David

2006-01-01

The helix-to-coil denaturation transition in DNA has been investigated in mixed solvents at high concentration using ultraviolet light absorption spectroscopy and small-angle neutron scattering. Two solvents have been used: water and ethylene glycol. The “melting” transition temperature was found to be 94°C for 4% mass fraction DNA/d-water and 38°C for 4% mass fraction DNA/d-ethylene glycol. The DNA melting transition temperature was found to vary linearly with the solvent fraction in the mixed solvents case. Deuterated solvents (d-water and d-ethylene glycol) were used to enhance the small-angle neutron scattering signal and 0.1M NaCl (or 0.0058 g/g mass fraction) salt concentration was added to screen charge interactions in all cases. DNA structural information was obtained by small-angle neutron scattering, including a correlation length characteristic of the inter-distance between the hydrogen-containing (desoxyribose sugar-amine base) groups. This correlation length was found to increase from 8.5 to 12.3 Å across the melting transition. Ethylene glycol and water mixed solvents were found to mix randomly in the solvation region in the helix phase, but nonideal solvent mixing was found in the melted coil phase. In the coil phase, solvent mixtures are more effective solvating agents than either of the individual solvents. Once melted, DNA coils behave like swollen water-soluble synthetic polymer chains. PMID:16815902

Nucleation in Polymers and Soft Matter

NASA Astrophysics Data System (ADS)

Xu, Xiaofei; Ting, Christina L.; Kusaka, Isamu; Wang, Zhen-Gang

2014-04-01

Nucleation is a ubiquitous phenomenon in many physical, chemical, and biological processes. In this review, we describe recent progress on the theoretical study of nucleation in polymeric fluids and soft matter, including binary mixtures (polymer blends, polymers in poor solvents, compressible polymer-small molecule mixtures), block copolymer melts, and lipid membranes. We discuss the methodological development for studying nucleation as well as novel insights and new physics obtained in the study of the nucleation behavior in these systems.

Molten Salt Thermal Energy Storage Systems

NASA Technical Reports Server (NTRS)

Maru, H. C.; Dullea, J. F.; Kardas, A.; Paul, L.; Marianowski, L. G.; Ong, E.; Sampath, V.; Huang, V. M.; Wolak, J. C.

1978-01-01

The feasibility of storing thermal energy at temperatures of 450 C to 535 C in the form of latent heat of fusion was examined for over 30 inorganic salts and salt mixtures. Alkali carbonate mixtures were chosen as phase-change storage materials in this temperature range because of their relatively high storage capacity and thermal conductivity, moderate cost, low volumetric expansion upon melting, low corrosivity, and good chemical stability. Means of improving heat conduction through the solid salt were explored.

Taking Advantage of Disorder: Small-Molecule Organic Glasses for Radiation Detection and Particle Discrimination

DOE PAGES

Carlson, Joseph S.; Marleau, Peter; Zarkesh, Ryan A.; ...

2017-06-20

A series of fluorescent silyl-fluorene molecules were synthesized and studied with respect to their photophysical properties and response toward ionizing neutron and gamma-ray radiation. Optically transparent and stable organic glasses were prepared from these materials using a bulk melt-casting procedure. The prepared organic glass monoliths provided fluorescence quantum yields and radiation detection properties exceeding the highest-performing benchmark materials such as solution-grown trans-stilbene crystals. Co-melts based on blends of two different glass-forming compounds were prepared with the goal of enhancing the stability of the amorphous state. Accelerated aging experiments on co-melt mixtures ranging from 0% to 100% of each component indicatedmore » improved resistance to recrystallization in the glass blends, able to remain fully amorphous for >1 month at 60 °C. Secondary dopants comprising singlet fluorophores or iridium organometallic compounds provided further improved detection efficiency, as evaluated by light yield and neutron/gamma particle discrimination measurements. As a result, optimized singlet and triplet doping levels were determined to be 0.05 wt % 1,4-bis(2-methylstyryl)benzene singlet fluorophore and 0.28 wt % Ir 3+, respectively.« less

Mantle potential temperature estimates and primary melt compositions of the Low-Ti Emeishan flood basalt

NASA Astrophysics Data System (ADS)

Shellnutt, J. G.; Pham, Thuy T.

2018-05-01

The Late Permian Emeishan large igneous province (ELIP) is considered to be one of the best examples of a mantle plume derived large igneous province. One of the primary observations that favour a mantle plume regime is the presence of ultramafic volcanic rocks. The picrites suggest primary mantle melts erupted and that mantle potential temperatures (TP) of the ELIP were > 200oC above ambient mantle conditions. However, they may represent a mixture of liquid and cumulus olivine and pyroxene rather than primary liquids. Consequently, temperature estimates based on the picrite compositions may not be accurate. Here we calculate mantle potential temperature (TP) estimates and primary liquids compositions using PRIMELT3 for the low-Ti (Ti/Y < 500) Emeishan basalt as they represent definite liquid compositions. The calculated TP yield a range from 1400oC to 1550oC, which is consistent with variability across a mantle plume axis. The primary melt compositions of the basalts are mostly picritic. The results of this study indicate that the Emeishan basalt was produced by a high temperature regime and that a few of the ultramafic volcanic rocks may be indicative of primary liquids.

Electrochemical Synthesis of Binary Carbides of Tungsten and Iron (Nickel, Cobalt) in Halide-Oxide Melts at 823 K

NASA Astrophysics Data System (ADS)

Kushkhov, Hasbi; Adamokova, Marina; Kvashin, Vitalij; Kardanov, Anzor; Gramoteeva, Svetlana

2007-12-01

Iron, cobalt and nickel powders are used as binding components for the production of articles of tungsten carbide by the hot pressing method. This fact and the unique properties of binary carbides of tungsten-iron triad metals encouraged the search for new ways of their synthesis. In the present work, the attempt to synthezise binary tungsten-nickel (cobalt, iron) carbides in molten KCl-NaCl-CsCl at 823 K was made. As a result of voltammetry research, it was established that in eutectic KCl-NaCl-CsCl melts the deposition potentials ofWand Ni (Co, Fe) differ by 150 - 350 mV from each other, which makes their co-deposition difficult. It is possible to shift the deposition potentials of tungsten and metals of the iron triad metals towards each other by changing the acid-base properties of the melt. The products of electrolysis in these molten system were identified by X-ray analysis. They are mixtures of tungsten and nickel (cobalt, iron) carbides: Ni2W4C, W6C2.54; Co3W3C, Co6W6C, W2C, Co3C; FeW3C.

Taking Advantage of Disorder: Small-Molecule Organic Glasses for Radiation Detection and Particle Discrimination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, Joseph S.; Marleau, Peter; Zarkesh, Ryan A.

A series of fluorescent silyl-fluorene molecules were synthesized and studied with respect to their photophysical properties and response toward ionizing neutron and gamma-ray radiation. Optically transparent and stable organic glasses were prepared from these materials using a bulk melt-casting procedure. The prepared organic glass monoliths provided fluorescence quantum yields and radiation detection properties exceeding the highest-performing benchmark materials such as solution-grown trans-stilbene crystals. Co-melts based on blends of two different glass-forming compounds were prepared with the goal of enhancing the stability of the amorphous state. Accelerated aging experiments on co-melt mixtures ranging from 0% to 100% of each component indicatedmore » improved resistance to recrystallization in the glass blends, able to remain fully amorphous for >1 month at 60 °C. Secondary dopants comprising singlet fluorophores or iridium organometallic compounds provided further improved detection efficiency, as evaluated by light yield and neutron/gamma particle discrimination measurements. As a result, optimized singlet and triplet doping levels were determined to be 0.05 wt % 1,4-bis(2-methylstyryl)benzene singlet fluorophore and 0.28 wt % Ir 3+, respectively.« less

Impact of Mutation Type and Amplicon Characteristics on Genetic Diversity Measures Generated Using a High-Resolution Melting Diversity Assay

PubMed Central

Cousins, Matthew M.; Donnell, Deborah; Eshleman, Susan H.

2013-01-01

We adapted high-resolution melting (HRM) technology to measure genetic diversity without sequencing. Diversity is measured as a single numeric HRM score. Herein, we determined the impact of mutation types and amplicon characteristics on HRM diversity scores. Plasmids were generated with single-base changes, insertions, and deletions. Different primer sets were used to vary the position of mutations within amplicons. Plasmids and plasmid mixtures were analyzed to determine the impact of mutation type, position, and concentration on HRM scores. The impact of amplicon length and G/C content on HRM scores was also evaluated. Different mutation types affected HRM scores to varying degrees (1-bp deletion < 1-bp change < 3-bp insertion < 9-bp insertion). The impact of mutations on HRM scores was influenced by amplicon length and the position of the mutation within the amplicon. Mutations were detected at concentrations of 5% to 95%, with the greatest impact at 50%. The G/C content altered melting temperature values of amplicons but had no impact on HRM scores. These data are relevant to the design of assays that measure genetic diversity using HRM technology. PMID:23178437

Validating predictions made by a thermo-mechanical model of melt segregation in sub-volcanic systems

NASA Astrophysics Data System (ADS)

Roele, Katarina; Jackson, Matthew; Morgan, Joanna

2014-05-01

A quantitative understanding of the spatial and temporal evolution of melt distribution in the crust is crucial in providing insights into the development of sub-volcanic crustal stratigraphy and composition. This work aims to relate numerical models that describe the base of volcanic systems with geophysical observations. Recent modelling has shown that the repetitive emplacement of mantle-derived basaltic sills, at the base of the lower crust, acts as a heat source for anatectic melt generation, buoyancy-driven melt segregation and mobilisation. These processes form the lowermost architecture of complex sub-volcanic networks as upward migrating melt produces high melt fraction layers. These 'porosity waves' are separated by zones with high compaction rates and have distinctive polybaric chemical signatures that suggest mixed crust and mantle origins. A thermo-mechanical model produced by Solano et al in 2012 has been used to predict the temperatures and melt fractions of successive high porosity layers within the crust. This model was used as it accounts for the dynamic evolution of melt during segregation and migration through the crust; a significant process that has been neglected in previous models. The results were used to input starting compositions for each of the layers into the rhyolite-MELTS thermodynamic simulation. MELTS then determined the approximate bulk composition of the layers once they had cooled and solidified. The mean seismic wave velocities of the polymineralic layers were then calculated using the relevant Voight-Reuss-Hill mixture rules, whilst accounting for the pressure and temperature dependence of seismic wave velocity. The predicted results were then compared with real examples of reflectivity for areas including the UK, where lower crustal layering is observed. A comparison between the impedance contrasts at compositional boundaries is presented as it confirms the extent to which modelling is able to make predictions that are consistent with the real data. This highlights improvements that could be made to the thermo-mechanical model, such as an extension into 3-D that would be capable of capturing the effects of convective instabilities. In addition, it describes how far numerical models are capable of reducing the uncertainty in the parameter space for poorly defined crustal properties. Most importantly however, it gives an improved understanding of the intrusion and development of melt zones in the continental crust that ultimately control the formation of volcanic systems. [1] Solano, J. M. S., M. D. Jackson, R. S. J. Sparks, J. D. Blundy, and C. Annen (2012). Melt segregation in deep crustal hot zones: a mechanism for chemical differentiation, crustal assimilation and the formation of evolved magmas. Journal of Petrology, 53, Number 10, Pages 1999-2026. DOI: 10.1093/petrology/egs041.

Ultrasonic Acoustic Velocities During Partial Melting of a Mantle Peridotite KLB-1

NASA Astrophysics Data System (ADS)

Weidner, Donald J.; Li, Li; Whitaker, Matthew L.; Triplett, Richard

2018-02-01

Knowledge of the elastic properties of partially molten rocks is crucial for understanding low-velocity regions in the interior of the Earth. Models of fluid and solid mixtures have demonstrated that significant decreases in seismic velocity are possible with small amounts of melt, but there is very little available data for testing these models, particularly with both P and S waves for mantle compositions. We report ultrasonic measurements of P and S velocities on a partially molten KLB-1 sample at mantle conditions using a multi-anvil device at a synchrotron facility. The P, S, and bulk sound velocities decrease as melting occurs. We find that the quantity, ∂lnVS/∂lnVB (where VB is the bulk sound velocity) is lower than mechanical models estimate. Instead, our data, as well as previous data in the literature, are consistent with a dynamic melting model in which melting and solidification interact with the stress field of the acoustic wave.

Partial reactive crystallization of variable CO2-bearing siliceous MORB-eclogite-derived melt in fertile peridotite and genesis of alkalic basalts with signatures of crustal recycling

NASA Astrophysics Data System (ADS)

Mallik, A.; Dasgupta, R.

2013-12-01

The presence of heterogeneity in the form of recycled altered oceanic crust (MORB-eclogite) has been proposed in the source of HIMU ocean island basalts (OIBs) [1]. Partial melts of recycled oceanic crust, however, are siliceous and Mg-poor and thus do not resemble the major element compositions of alkalic OIBs that are silica-poor and Mg-rich. In an upwelling heterogenous mantle, MORB-eclogite undergoes melting deeper than volatile-free peridotite, hence, andesitic partial melt derived from eclogite will react with subsolidus peridotite. We have examined the effect of such a melt-rock reaction under volatile-free conditions at 1375 °C, 3 GPa by varying the melt-rock ratio from 8 to 50 wt.% [2]. We concluded that the reacted melts reproduce certain major element characteristics of oceanic basanites, but not nephelinites. Also, the melt-rock reaction produces olivine and garnet-bearing websteritic residue. Because presence of CO2 has been invoked in the source of many HIMU ocean islands, the effect of CO2 on such a melt-rock reaction needs to be evaluated. Accordingly, we performed reaction experiments on mixtures of 25% and 33% CO2-bearing andesitic partial melt and peridotite at 1375 °C, 3 GPa by varying the dissolved CO2 content of the reacting melts from 1 to 5 wt.% (bulk CO2 from 0.25 to 1.6 wt.%) [3, this study]. Owing to melt-rock reaction, with increasing CO2 in the bulk mixture, (a) modes of olivine and cpx decrease while melt, opx and garnet increase, (b) reacted melts evolve to greater degree of Si-undersaturation (from andesite through basanite to nephelinite), (c) enhanced crystallization of garnet take place with higher CO2 in the melt, reducing alumina content of the reacted melts, and (d) CaO and MgO content of the reacted melts increase, without affecting FeO* and Na2O contents (indicating greater propensity of Ca2+ and Mg2+ over Fe2+ and Na+ to enter silicate melt as carbonate). For a given melt-MgO, the CO2-bearing reacted melts are a better match for alkalic basalts in terms of SiO2, Al2O3, CaO and CaO/Al2O3 than the CO2-free ones [3]. Using the experimental data, we have further developed an empirical model to predict mineral modes in residue and reacted melt compositions for olivine-opx saturated lithologies as a function of melt:rock ratio and bulk CO2 content. For example, in case of 5 wt.% eclogite melt infiltrating in fertile peridotite, with bulk CO2 from 0 to 2 wt.%, the derivative melts show an increase in CaO and MgO from 11 to 16 wt.%, 15 to 24 wt.%, respectively and decrease in SiO2 and Al2O3 from 45 to 39 wt.% and 14 to 5 wt.%, respectively. From this model, we have created a major element composition space of MORB-eclogite-derived reactive melt mass vs. bulk CO2 and we predict that primary HIMU-type magmas require <5 to 10 wt.% of MORB-eclogite melt input and up to 0.8 wt.% bulk CO2 in their source. Our model also allows determining the residual lithology at the source of alkalic basalts, produced owing to eclogite melt-peridotite reaction with or without CO2. [1] Jackson & Dasgupta (2008) EPSL 276, 175-186. [2] Mallik & Dasgupta (2012) EPSL 329-330, 97-108. [3] Mallik & Dasgupta (in press) JPetrol.

Synthesis and Properties of a Clean and Sustainable Deicing Additive for Asphalt Mixture

PubMed Central

Peng, Chao; Yu, Jianying; Zhao, Zhijie; Dai, Jing; Fu, Jingyi; Zhao, Meiling; Wang, Wei

2015-01-01

A clean and sustainable deicing additive was prepared via the adsorption of acetate anions (Ac-) by magnesium (Mg) and aluminum (Al) calcined layered double hydroxide (Mg/Al-CLDH). Fourier transform infrared spectroscopy spectrums proved that Ac- had intercalated into LDH structure. X-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy images showed that the intercalation spacing and platelet thickness of Mg and Al layered double hydroxide containing Ac- anions (Mg/Al-Ac- LDH) had been enlarged due to substitution of divalent CO3 2- anions by a larger quantity of monovalent Ac– anions. Differential scanning calorimetry tests testified that the insoluble Mg2/Al-Ac- LDH evidently decreased the freeze point (FP) of water to -10.68°C. X-ray photoelectron spectroscopy analyses confirmed that the Ac- were strongly confined by the metal layers of LDHs. FP test of asphalt mixtures confirmed that Mg/Al-Ac- LDHs reduced FP to -5.5°C. Immersion test results indicated that Mg/Al-Ac- LDH had a good deicing durability and Ac- did not released from asphalt mixture. Snow melting observation was conducted further testified that Mg/Al-Ac- LDH melted snow or ice sustainably. PMID:25625279

Synthesis and properties of a clean and sustainable deicing additive for asphalt mixture.

PubMed

Peng, Chao; Yu, Jianying; Zhao, Zhijie; Dai, Jing; Fu, Jingyi; Zhao, Meiling; Wang, Wei

2015-01-01

A clean and sustainable deicing additive was prepared via the adsorption of acetate anions (Ac-) by magnesium (Mg) and aluminum (Al) calcined layered double hydroxide (Mg/Al-CLDH). Fourier transform infrared spectroscopy spectrums proved that Ac- had intercalated into LDH structure. X-ray diffraction patterns, scanning electron microscopy and transmission electron microscopy images showed that the intercalation spacing and platelet thickness of Mg and Al layered double hydroxide containing Ac- anions (Mg/Al-Ac- LDH) had been enlarged due to substitution of divalent CO32- anions by a larger quantity of monovalent Ac- anions. Differential scanning calorimetry tests testified that the insoluble Mg2/Al-Ac- LDH evidently decreased the freeze point (FP) of water to -10.68°C. X-ray photoelectron spectroscopy analyses confirmed that the Ac- were strongly confined by the metal layers of LDHs. FP test of asphalt mixtures confirmed that Mg/Al-Ac- LDHs reduced FP to -5.5°C. Immersion test results indicated that Mg/Al-Ac- LDH had a good deicing durability and Ac- did not released from asphalt mixture. Snow melting observation was conducted further testified that Mg/Al-Ac- LDH melted snow or ice sustainably.

Characterization of crystal forms of β-estradiol thermal analysis, Raman microscopy, X-ray analysis and solid-state NMR

NASA Astrophysics Data System (ADS)

Variankaval, N. E.; Jacob, K. I.; Dinh, S. M.

2000-08-01

The structure and select crystalline properties of a common drug (estradiol) used in a transdermal drug delivery system are investigated. Four different crystal forms of estradiol (EA, EC, ED and EM) were prepared in the laboratory and characterized by thermal analysis, optical microscopy, Raman microspectroscopy, and solid-state NMR. Variable temperature X-ray studies were carried out on form A (EA) to determine whether the crystal structure changed as a function of temperature. These four forms exhibited different thermal behavior. EA and EC had similar melting points. This study clearly shows that water cannot be released from the crystal lattice of EA unless melting is achieved, and exposing EA to temperatures below the melting point only results in a partial release of hydrogen bonded water. EC was prepared by melting EA and subsequently cooling it to room temperature. Form EC was anhydrous, as it did not exhibit water loss, as opposed to EA, which had about 3.5% water in its crystal structure. ED was very difficult to prepare and manifested itself only as a mixture with EC. Its melting point was about 10°C lower than that of EC. It is thought to be an unstable form due to its simultaneous occurrence with EC and the inability to isolate it. EM is a solvate of methanol, not a polymorph. Its melting point was similar to EA and EC. From thermogravimetry/differential thermal analysis and differential scanning calorimetry data, it was apparent that estradiol formed a hemisolvate with methanol. All four forms had different morphologies. Raman microscopy was carried out on the different crystal forms. The spectra of EC and ED were almost identical. Thermal analysis revealed that this is due to the highly unstable nature of ED and its tendency to either convert spontaneously to EC or occur in mixtures with it.

[Utilization of a transferred arc-plasma rotating furnace to melt and found oxide mixtures at around 2000 degrees C (presentation of the film VULCANO)].

PubMed

Cognet, G; Laffont, G; Jegou, C; Pierre, J; Journeau, C; Sudreau, F; Roubaud, A

1999-03-01

Unless security measures are taken, a hypothetical accident resulting from the loss of the cooling circuit in a pressurized water nuclear reactor could cause the heart of the reactor to melt forming a bath, called the corium, mainly composed of uranium, zirconium and iron oxides as well as the structural steel. This type of situation would be similar to the Three Mile Island accident in 1979. In order to limit the consequences of such an accident, the Atomic Energy Commission has implemented a large study program [1] to improve our understanding of corium behavior and determine solutions to stabilize it and avoid its propagation outside the unit. The VULCANO installation was designed in order to perform the trials using real materials which are indispensable to study all the phenomena involved. A film on the VULCANO trials was presented at the Henri Moissan commemorative session organized by the French National Academy of Pharmacy. The rotating furnace used to melt and found the mixture simulating the corium is a direct descendant of the pioneer work by Henri Moissan. An electrical arc is directed at the center of the load to melt which is maintained against the walls by centrifugal force. After six high-temperature trials performed with compositions without uranium oxide, the first trial with real corium showed that the magma spread rather well, a result which is quite favorable for cooling.

Nanostructure, hydrogen bonding and rheology in choline chloride deep eutectic solvents as a function of the hydrogen bond donor.

PubMed

Stefanovic, Ryan; Ludwig, Michael; Webber, Grant B; Atkin, Rob; Page, Alister J

2017-01-25

Deep eutectic solvents (DESs) are a mixture of a salt and a molecular hydrogen bond donor, which form a eutectic liquid with a depressed melting point. Quantum mechanical molecular dynamics (QM/MD) simulations have been used to probe the 1 : 2 choline chloride-urea (ChCl : U), choline chloride-ethylene glycol (ChCl : EG) and choline chloride-glycerol (ChCl : Gly) DESs. DES nanostructure and interactions between the ions is used to rationalise differences in DES eutectic point temperatures and viscosity. Simulations show that the structure of the bulk hydrogen bond donor is largely preserved for hydroxyl based hydrogen bond donors (ChCl:Gly and ChCl:EG), resulting in a smaller melting point depression. By contrast, ChCl:U exhibits a well-established hydrogen bond network between the salt and hydrogen bond donor, leading to a larger melting point depression. This extensive hydrogen bond network in ChCl:U also leads to substantially higher viscosity, compared to ChCl:EG and ChCl:Gly. Of the two hydroxyl based DESs, ChCl:Gly also exhibits a higher viscosity than ChCl:EG. This is attributed to the over-saturation of hydrogen bond donor groups in the ChCl:Gly bulk, which leads to more extensive hydrogen bond donor self-interaction and hence higher cohesive forces within the bulk liquid.

Nonequilibrium Diamond Growth during the High-Temperature High-Pressure Synthesis of a Composite Material Made of a Mixture of Cobalt and Fullerene Powders

NASA Astrophysics Data System (ADS)

Bulienkov, N. A.; Zheligovskaya, E. A.; Chernogorova, O. P.; Drozdova, E. I.; Ushakova, I. N.; Ekimov, E. A.

2018-01-01

A composite material (CM) reinforced by diamond particles is fabricated from a mixture of cobalt and 10 wt % C60 powders at a pressure of 8 GPa and a temperature of 1200-1300°C, which is close to the melting temperature of the metastable Co-C eutectic. The results of X-ray diffraction, Raman spectroscopy, and electron-probe microanalysis demonstrate that the CM consists of diamond and the Co3C carbide. Diamond crystals are shown to grow as plates parallel to a {100} plane according to the mechanism of nonequilibrium normal growth during liquid-phase CM synthesis. The diamond particles have a hardness of 82 GPa at an elastic recovery of 95%. The structure of the synthesized cobalt-based CM with diamond inclusions ensures its ultrahigh wear resistance and antifriction properties.

Biodegradable packaging materials conception based on starch and polylactic acid (PLA) reinforced with cellulose.

PubMed

Masmoudi, Fatma; Bessadok, Atef; Dammak, Mohamed; Jaziri, Mohamed; Ammar, Emna

2016-10-01

The plastic materials used for packaging are increasing leading to a considerable amount of undegradable solid wastes. This work deals with the reduction of conventional plastics waste and the natural resources preservation by using cellulosic polymers from renewable resources (alfa and luffa). Plasticized starch films syntheses were achieved at a laboratory scale. These natural films showed some very attractive mechanical properties at relatively low plasticizers levels (12 to 17 % by weight). Furthermore, mixtures including polylactic acid polymer (PLA) and cellulose fibers extracted from alfa and luffa were investigated by melt extrusion technique. When used at a rate of 10 %, these fibers improved the mixture mechanical properties. Both developed materials were biodegradable, but the plasticized starch exhibited a faster biodegradation kinetic compared to the PLA/cellulose fibers. These new materials would contribute to a sustainable development and a waste reduction.

Antireflection coatings based on fluoride formulations for organic solar cells

NASA Astrophysics Data System (ADS)

Suleimanov, S. Kh.; Berger, P.; Dyskin, V. G.; Dzhanklych, M. U.; Bugakov, A. G.; Dudko, O. A.; Kulagina, N. A.; Kim, M.

2016-04-01

An alloy of a mixture of fluorides MgF2 and AlF3 with CaF2 has been obtained in a 3-kW solar furnace. It was supposed that a minor CaF2 additive compensates for the tensile stresses appearing in thin MgF2 and AlF3 films, with their mechanical properties being thereby improved. The results of X-ray phase analysis demonstrated that both components of the mixture are present in the alloy, while the complex oxide CaAl4O7, the formation of which is attributed to the melting in air, is only identified in AlF3: CaF2 = 95: 5 (wt %). The increase in the transmittance of glass and polyethylene terephthalate upon deposition onto their surface of a thin film of the material synthesized in the study is due to the optical properties of AlF3 and MgF2.

Bonding of sapphire to sapphire by eutectic mixture of aluminum oxide and zirconium oxide

NASA Technical Reports Server (NTRS)

Deluca, J. J. (Inventor)

1975-01-01

Bonding of an element comprising sapphire, ruby or blue sapphire to another element of such material with a eutectic mixture of aluminum oxide and zirconium oxide is discussed. The bonding mixture may be applied in the form of a distilled water slurry or by electron beam vapor deposition. In one embodiment the eutectic is formed in situ by applying a layer of zirconium oxide and then heating the assembly to a temperature above the eutectic temperature and below the melting point of the material from which the elements are formed. The formation of a sapphire rubidium maser cell utilizing eutectic bonding is shown.

Apollo 16 impact-melt splashes - Petrography and major-element composition

NASA Technical Reports Server (NTRS)

See, Thomas H.; Horz, Friedrich; Morris, Richard V.

1986-01-01

Petrographic and major-element analyses are applied to 50 Apollo 16 impact-melt splash (IMS) samples in order to determine their origin and assess the nature of the subregolith source. The macroscopic analyses reveal that the IMSs exhibit a glassy appearance, but the textures range from holohyaline to hyalopilitic. Schlieren-rich glasses dominate the holohyaline areas, and the crystalline areas are mainly spherulitic. It is observed that most IMSs contain feldspathic monomineralic and lithic clasts and no regolithic materials. It is detected that the chemistry of most IMSs is not like the local regolith and appears to represent varied mixtures of VHA impact-melt breccias and anorthosite; the host rocks are mainly dimict breccias. It is concluded that the Cayley Formation is a polymict deposit composed of VHA impact-melt breccias and anorthosites. Tables revealing the macroscopic characteristics of the IMSs and the major-element composition of IMSs and various host rock are presented.

Prediction of U-Mo dispersion nuclear fuels with Al-Si alloy using artificial neural network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Susmikanti, Mike, E-mail: mike@batan.go.id; Sulistyo, Jos, E-mail: soj@batan.go.id

2014-09-30

Dispersion nuclear fuels, consisting of U-Mo particles dispersed in an Al-Si matrix, are being developed as fuel for research reactors. The equilibrium relationship for a mixture component can be expressed in the phase diagram. It is important to analyze whether a mixture component is in equilibrium phase or another phase. The purpose of this research it is needed to built the model of the phase diagram, so the mixture component is in the stable or melting condition. Artificial neural network (ANN) is a modeling tool for processes involving multivariable non-linear relationships. The objective of the present work is to developmore » code based on artificial neural network models of system equilibrium relationship of U-Mo in Al-Si matrix. This model can be used for prediction of type of resulting mixture, and whether the point is on the equilibrium phase or in another phase region. The equilibrium model data for prediction and modeling generated from experimentally data. The artificial neural network with resilient backpropagation method was chosen to predict the dispersion of nuclear fuels U-Mo in Al-Si matrix. This developed code was built with some function in MATLAB. For simulations using ANN, the Levenberg-Marquardt method was also used for optimization. The artificial neural network is able to predict the equilibrium phase or in the phase region. The develop code based on artificial neural network models was built, for analyze equilibrium relationship of U-Mo in Al-Si matrix.« less

Target-projectile interaction during impact melting at Kamil Crater, Egypt

NASA Astrophysics Data System (ADS)

Fazio, Agnese; D'Orazio, Massimo; Cordier, Carole; Folco, Luigi

2016-05-01

In small meteorite impacts, the projectile may survive through fragmentation; in addition, it may melt, and chemically and physically interact with both shocked and melted target rocks. However, the mixing/mingling between projectile and target melts is a process still not completely understood. Kamil Crater (45 m in diameter; Egypt), generated by the hypervelocity impact of the Gebel Kamil Ni-rich ataxite on sandstone target, allows to study the target-projectile interaction in a simple and fresh geological setting. We conducted a petrographic and geochemical study of macroscopic impact melt lapilli and bombs ejected from the crater, which were collected during our geophysical campaign in February 2010. Two types of glasses constitute the impact melt lapilli and bombs: a white glass and a dark glass. The white glass is mostly made of SiO2 and it is devoid of inclusions. Its negligible Ni and Co contents suggest derivation from the target rocks without interaction with the projectile (<0.1 wt% of projectile contamination). The dark glass is a silicate melt with variable contents of Al2O3 (0.84-18.7 wt%), FeOT (1.83-61.5 wt%), and NiO (<0.01-10.2 wt%). The dark glass typically includes fragments (from few μm to several mm in size) of shocked sandstone, diaplectic glass, lechatelierite, and Ni-Fe metal blebs. The metal blebs are enriched in Ni compared to the Gebel Kamil meteorite. The dark glass is thus a mixture of target and projectile melts (11-12 wt% of projectile contamination). Based on recently proposed models for target-projectile interaction and for impact glass formation, we suggest a scenario for the glass formation at Kamil. During the transition from the contact and compression stage and the excavation stage, projectile and target liquids formed at their interface and chemically interact in a restricted zone. Projectile contamination affected only a shallow portion of the target rocks. The SiO2 melt that eventually solidified as white glass behaved as an immiscible liquid and did not interact with the projectile. During the excavation stage dark glass melt engulfed and coated the white glass melt, target fragments, and got stuck to iron meteorite shrapnel fragments. This model could also explain the common formation of white and dark glasses in small impact craters generated by iron bodies (e.g., Wabar).

Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

NASA Astrophysics Data System (ADS)

Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

2014-12-01

The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

On melt solutions for the growth of CaTiO3 crystals

NASA Astrophysics Data System (ADS)

Klimm, Detlef; Schmidt, Max; Wolff, Nora; Guguschev, Christo; Ganschow, Steffen

2018-03-01

When calcium titanate crystals are grown from stoichiometric melts, they crystallize in the cubic perovskite structure. Upon cooling to room temperature they undergo subsequent phase transitions to tetragonal and orthorhombic modifications. These phase transitions are disruptive and result in severely damaged crystals. This paper presents differential thermal analysis data for several prospective solvents, with the aim to identify a system offering the possibility to perform crystal growth of undistorted CaTiO3 crystals by crystallizing them significantly below the melting point directly in the low temperature modification. From mixtures CaF2:TiO2:CaTiO3 = 3:1:1 (molar ratio) the growth of undistorted, at least millimeter-sized CaTiO3 crystals is possible.

Enzymatic temperature change indicator

DOEpatents

Klibanov, Alexander M.; Dordick, Jonathan S.

1989-01-21

A temperature change indicator is described which is composed of an enzyme and a substrate for that enzyme suspended in a solid organic solvent or mixture of solvents as a support medium. The organic solvent or solvents are chosen so as to melt at a specific temperature or in a specific temperature range. When the temperature of the indicator is elevated above the chosen, or critical temperature, the solid organic solvent support will melt, and the enzymatic reaction will occur, producing a visually detectable product which is stable to further temperature variation.

PLUTONIUM-CERIUM-COBALT AND PLUTONIUM-CERIUM-NICKEL ALLOYS

DOEpatents

Coffinberry, A.S.

1959-08-25

>New plutonium-base teroary alloys useful as liquid reactor fuels are described. The alloys consist of 10 to 20 atomic percent cobalt with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 88 atomic percent; or, of from 10 to 25 atomic percent nickel (or mixture of nickel and cobalt) with the remainder plutonium and cerium in any desired proportion, with the plutonium not in excess of 86 atomic percent. The stated advantages of these alloys over unalloyed plutonium for reactor fuel use are a lower melting point and a wide range of permissible plutonium dilution.

Recoverable immobilization of transuranic elements in sulfate ash

DOEpatents

Greenhalgh, Wilbur O.

1985-01-01

Disclosed is a method of reversibly immobilizing sulfate ash at least about 20% of which is sulfates of transuranic elements. The ash is mixed with a metal which can be aluminum, cerium, samarium, europium, or a mixture thereof, in amounts sufficient to form an alloy with the transuranic elements, plus an additional amount to reduce the transuranic element sulfates to elemental form. Also added to the ash is a fluxing agent in an amount sufficient to lower the percentage of the transuranic element sulfates to about 1% to about 10%. The mixture of the ash, metal, and fluxing agent is heated to a temperature sufficient to melt the fluxing agent and the metal. The mixture is then cooled and the alloy is separated from the remainder of the mixture.

Insight into the Li2CO3-K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics

NASA Astrophysics Data System (ADS)

Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

2016-03-01

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li2CO3-K2CO3 (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self-diffusion coefficients, viscosity, and ionic conductivity.

Insight into the Li2CO3-K2CO3 eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics.

PubMed

Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

2016-03-14

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li2CO3-K2CO3 (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900-1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, we present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture's self-diffusion coefficients, viscosity, and ionic conductivity.

A novel pre-sintering technique for the growth of Y-Ba-Cu-O superconducting single grains from raw metal oxides

NASA Astrophysics Data System (ADS)

Li, Jiawei; Shi, Yun-Hua; Dennis, Anthony R.; Namburi, Devendra Kumar; Durrell, John H.; Yang, Wanmin; Cardwell, David A.

2017-09-01

Most established top seeded melt growth (TSMG) processes of bulk, single grain Y-Ba-Cu-O (YBCO) superconductors are performed using a mixture of pre-reacted precursor powders. Here we report the successful growth of large, single grain YBCO samples by TSMG with good superconducting properties from a simple precursor composition consisting of a sintered mixture of the raw oxides. The elimination of the requirement to synthesize precursor powders in a separate process prior to melt processing has the potential to reduce significantly the cost of bulk superconductors, which is essential for their commercial exploitation. The growth morphology, microstructure, trapped magnetic field and critical current density, J c, at different positions within the sample and maximum levitation force of the YBCO single grains fabricated by this process are reported. Measurements of the superconducting properties show that the trapped filed can reach 0.45 T and that a zero field J c of 2.5 × 104 A cm-2 can be achieved in these samples. These values are comparable to those observed in samples fabricated using pre-reacted, high purity commercial oxide precursor powders. The experimental results are discussed and the possibility of further improving the melt process using raw oxides is outlined.

Experimental calibration of a new oxybarometer for silicic magmas based on the partitioning of vanadium between magnetite and silicate melt

NASA Astrophysics Data System (ADS)

Arató, Róbert; Audétat, Andreas

2016-04-01

Oxygen fugacity is an important parameter in magmatic systems that affects the stability of mineral phases and fluid species. However, there is no well-established method to reconstruct the oxygen fugacity of slowly cooled magmas such as granite, for example, because existing oxybarometers (e.g., magnetite-ilmenite method) are susceptible to re-equilibration processes during slow cooling and thus lead to erroneous results when applied for granitic rocks. In this study, we aim at developing an oxybarometer that is based on the partitioning of vanadium (a redox-sensitive element) between magnetite inclusions and silicate melt inclusions preserved in quartz phenocrysts, where they were protected from subsolidus alteration and can be measured as entities by LA-ICP-MS. In the first - experimental - part of this study we investigated the effects of temperature (800-950 ° C), pressure (1-2 kbar), oxygen fugacity (from ΔFMQ+0.7 to ΔFMQ+4.0), magnetite composition, and melt composition on the partition coefficient of vanadium between magnetite and melt (DVmgt-melt). The experiments were carried out in cold-seal pressure vessels and the starting material was a mixture of V-doped haplogranite glasses or natural obsidian powder with variable aluminum saturation index (ASI), and synthetic, V-free magnetite of 10-20 μm grain size. The vanadium partition coefficient was found to depend strongly on oxygen fugacity, and to lesser (but still considerable) degrees on melt composition and temperature. A more than 1.5 log unit decrease in DVmgt-melt values with increasing oxygen fugacity can be explained by a change of the dominant valence state of V in the silicate melt. For a given oxygen fugacity buffer DVmgt-melt decreases with increasing temperature, but this reflects mostly the change in absolute fO2 values while the net temperature effect is in fact positive. DVmgt-melt depends significantly on melt composition, resulting in higher D-values with increasing aluminum saturation index (ASI). This seems to reflect less favorable incorporation of V into peraluminous melts compared to depolymerized, peralkaline melts. Changing pressure from 1 to 2 kbar had an effect only at NNO, causing 0.3 log unit increase in D, whereas the Ti-content of magnetite turned out to have negligible effect on the V partitioning. In summary, the dependence of DVmgt-melt on temperature, ASI and oxygen fugacity can be described by the following regression equation: logD(V)mgt/melt=-1.22+0.31*10^5/T(° K) +1.73*ASI -0.49*ΔFMQ First tests of the equation on natural samples were carried out on rapidly cooled tuffs and vitrophyres from variable tectonic settings, for which fO2 could be constrained independently by the magnetite-ilmenite method. All calculated fO2 values fall within ± 0.75 log unit within those suggested by the Fe-Ti oxybarometer, whereas 12 out of 16 samples agree within 0.5 log units .

Using the low-temperature plasma in cement production

NASA Astrophysics Data System (ADS)

Sazonova, N. A.; Skripnikova, N. K.

2015-11-01

The calculation of the raw-material mixtures and mineralogical composition of the cement clinkers which are synthezed on their base taking into account the disbalanced crystallization of the melting and glassing under conditions of the low-temperature plasma was performed. The difference of the actual values from the calculated ones is 0.69-3.73%. The composition which is characterized as the saturation coefficient 0,88; the silicate module - 3.34, the alumina module - 2.52 in melting of which the alite in amount 78.7%; 3CaO·SiO2 - 4%; 3CaO·Al2O3 - 9.8%; 12CaO·7Al2O3 -2.9%; CaOfree - 1% formed using the lime-stone from the quarry «Pereval» in the town of Slyudyanka and the clay from the deposit «Maximovski» in Irkutsk Region is considered as the optimal one. The structure of the melted clinker is represented as the metastable minerals of alite in the lamellar form with the dimensions up to (3-20)×(80-400) μm and the ratio of length to width 26.6-133. The elongated crystal form may stipulate the high cement activity based on the melted clinkers, which is 82.7-84.2 MPa. Valid- ing the revealed high activity of the viscous substance was confirmed by the results of the scanning electronic microscopy, X-ray phase analysis, with using of which the quantitative and qualitative analyses of the clinker minerals having the deformed crystalic lattice; were performed the morphology of the minerals in the clinker and cement stone, received on its ground, was studied.

Assessment of a Novel Ternary Eutectic Chloride Salt for Next Generation High-Temperature Sensible Heat Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vidal, Judith C; Mohan, Gowtham; Venkataraman, Mahesh

A novel ternary eutectic salt mixture for high-temperature sensible heat storage, composed of sodium chloride, potassium chloride and magnesium chloride (NaKMg-Cl) was developed based on a phase diagram generated with FactSage(R). The differential scanning calorimetry (DSC) technique was used to experimentally validate the predicted melting point of the ternary eutectic composition, which was measured as 387 degrees C, in good agreement with the prediction. The ternary eutectic was compared to two binary salts formulated based on prediction of the eutectic composition by FactSage, but unfortunately DSC measurements showed that neither binary salt composition was eutectic. Nonetheless, the measured thermo-physical propertiesmore » of the ternary and the two binary mixtures are compared. Liquid heat capacities of both the ternary and binary salts were determined by using DSC with sapphire as the standard reference. The average heat capacity of the ternary mixture was recorded as 1.18 J g-1 K-1. The mass loss of the molten eutectic salts was studied up to 1000 degrees C using a thermogravimetric analyser in nitrogen, argon and air. The results showed a significant mass loss due to vaporisation in an open system, particularly above 700 degrees C. However, simulation of mass loss in a closed system with an inert cover gas indicates storage temperatures above 700 degrees C may be feasible, and highlights the importance of the design of the storage tank system. In terms of storage material cost, the NaKMg-Cl mixture is approximately 4.5 USD/kWh, which is 60% cheaper than current state-of-the-art nitrate salt mixtures.« less

Two-step infiltration of aluminum melts into Al-Ti-B4C-CuO powder mixture pellets

NASA Astrophysics Data System (ADS)

Zhang, Jingjing; Lee, Jung-Moo; Cho, Young-Hee; Kim, Su-Hyeon; Yu, Huashun

2016-03-01

Aluminum matrix composites with a high volume fraction of B4C and TiB2 were fabricated by a novel processing technique - a quick spontaneous infiltration process. The process combines a pressureless infiltration with the combustion reaction of Al-Ti-B4C-CuO in molten aluminum. The process is realized in a simple and economical way in which the whole process is performed in air in a few minutes. To verify the rapidity of the process, the infiltration kinetics was calculated based on the Washburn equation in which melt flows into a porous skeleton. However, there was a noticeable deviation from the calculated results with the experimental results. Considering the cross-sections of the samples at different processing times, a new infiltration model (two step infiltration) consisting of macro-infiltration and micro-infiltration is suggested. The calculated kinetics results in light of the proposed model agree well with the experimental results.

Determination of chemical speciations of cerium in nuclear waste glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Meiling; Li, Hong

1996-12-31

Cerium oxides have been widely used as a surrogate for plutonium in the investigation of the melt and durability behavior of simulated nuclear waste glasses. It is well known that there is a cerous-ceric equilibrium in silicate glasses under normal melting conditions. The position of this equilibrium depends on glass composition, melting temperature, furnace atmosphere, and possibly the total amounts of cerium in glass. The oxidation state of cerium affects total solubility of cerium in glass, solubilities of other components in glass, viscosities and liquidus temperatures of the melts, and the chemical durability of the glasses. A procedure was developedmore » for the determination of the ceric and cerous distribution. The glass was ground to small particles of less than 300 meshes and was dissolved in mixture of HF and H{sub 2}SO{sub 4}. The ceric oxide was graduately reduced to cerous species in the presence of HF acid during the dissolution. To compensate the change of the equilibrium during the dissolution, a calibration curve is made with a mixture of standard solution of ceric sulphate and one gram of glass of the same composition containing no cerium. Boric acid was added to complex the fluoride ions, and the resultant solution was titrated potentiometrically with 0.01 N ferrous ammonium sulphate solution. The corrected ceric concentration was obtained on the calibration curve. The total cerium content in the above solution was analyzed using ICP-AES and the cerous content was the difference between the total Ce and Ce(+4).« less

The calcium fluoride effect on properties of cryolite melts feasible for low-temperature production of aluminum and its alloys

NASA Astrophysics Data System (ADS)

Tkacheva, O.; Dedyukhin, A.; Redkin, A.; Zaikov, Yu.

2017-07-01

The CaF2 effect on the liquidus temperature, electrical conductivity and alumina solubility in the potassium-sodium and potassium-lithium cryolite melts with cryolite ratio (CR = (nKF+nMF)/nAlF3, M = Li, Na) 1.3 was studied. The liquidus temperature in the quisi-binary system [KF-LiF-AlF3]-CaF2 changes with the same manner as in the [KF-NaF-AlF3]-CaF2. The electrical conductivity in the KF-NaF-AlF3-CaF2 melt decreases with increasing the CaF2 content, but it slightly raises with the first small addition of CaF2 into the KF-LiF-AlF3-CaF2 melts, enriched with KF, which was explained by the increased K+ ions mobility due to their relatively low ionic potential. The contribution of the Li+ cations in conductivity of the KF-LiF-AlF3-CaF2 electrolyte is not noteworthy. The Al2O3 solubility in the KF-NaF-AlF3 electrolyte rises with the increasing KF content, but the opposite tendency is observed in the cryolite mixtures containing CaF2. The insoluble compounds - KCaAl2F9 or KCaF3 - formed in the molten mixtures containing potassium and calcium ions endorse the increase of the liquidus temperature. The calcium fluoride effect on the side ledge formation in the electrolytic cell during low-temperature aluminum electrolysis is discussed.

A thermodynamic approach to model the caloric properties of semicrystalline polymers

NASA Astrophysics Data System (ADS)

Lion, Alexander; Johlitz, Michael

2016-05-01

It is well known that the crystallisation and melting behaviour of semicrystalline polymers depends in a pronounced manner on the temperature history. If the polymer is in the liquid state above the melting point, and the temperature is reduced to a level below the glass transition, the final degree of crystallinity, the amount of the rigid amorphous phase and the configurational state of the mobile amorphous phase strongly depend on the cooling rate. If the temperature is increased afterwards, the extents of cold crystallisation and melting are functions of the heating rate. Since crystalline and amorphous phases exhibit different densities, the specific volume depends also on the temperature history. In this article, a thermodynamically based phenomenological approach is developed which allows for the constitutive representation of these phenomena in the time domain. The degree of crystallinity and the configuration of the amorphous phase are represented by two internal state variables whose evolution equations are formulated under consideration of the second law of thermodynamics. The model for the specific Gibbs free energy takes the chemical potentials of the different phases and the mixture entropy into account. For simplification, it is assumed that the amount of the rigid amorphous phase is proportional to the degree of crystallinity. An essential outcome of the model is an equation in closed form for the equilibrium degree of crystallinity in dependence on pressure and temperature. Numerical simulations demonstrate that the process dependences of crystallisation and melting under consideration of the glass transition are represented.

A thermodynamical model for the surface tension of silicate melts in contact with H2O gas

USGS Publications Warehouse

Colucci, Simone; Battaglia, Maurizio; Trigila, Raffaello

2016-01-01

Surface tension plays an important role in the nucleation of H2O gas bubbles in magmatic melts and in the time-dependent rheology of bubble-bearing magmas. Despite several experimental studies, a physics based model of the surface tension of magmatic melts in contact with H2O is lacking. This paper employs gradient theory to develop a thermodynamical model of equilibrium surface tension of silicate melts in contact with H2O gas at low to moderate pressures. In the last decades, this approach has been successfully applied in studies of industrial mixtures but never to magmatic systems. We calibrate and verify the model against literature experimental data, obtained by the pendant drop method, and by inverting bubble nucleation experiments using the Classical Nucleation Theory (CNT). Our model reproduces the systematic decrease in surface tension with increased H2O pressure observed in the experiments. On the other hand, the effect of temperature is confirmed by the experiments only at high pressure. At atmospheric pressure, the model shows a decrease of surface tension with temperature. This is in contrast with a number of experimental observations and could be related to microstructural effects that cannot be reproduced by our model. Finally, our analysis indicates that the surface tension measured inverting the CNT may be lower than the value measured by the pendant drop method, most likely because of changes in surface tension controlled by the supersaturation.

Kinetics of Cold-Cap Reactions for Vitrification of Nuclear Waste Glass Based on Simultaneous Differential Scanning Calorimetry - Thermogravimetry (DSC-TGA) and Evolved Gas Analysis (EGA)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, Carmen P.; Pierce, David A.; Schweiger, Michael J.

2013-12-03

For vitrifying nuclear waste glass, the feed, a mixture of waste with glass-forming and modifying additives, is charged onto the cold cap that covers 90-100% of the melt surface. The cold cap consists of a layer of reacting molten glass floating on the surface of the melt in an all-electric, continuous glass melter. As the feed moves through the cold cap, it undergoes chemical reactions and phase transitions through which it is converted to molten glass that moves from the cold cap into the melt pool. The process involves a series of reactions that generate multiple gases and subsequent massmore » loss and foaming significantly influence the mass and heat transfers. The rate of glass melting, which is greatly influenced by mass and heat transfers, affects the vitrification process and the efficiency of the immobilization of nuclear waste. We studied the cold-cap reactions of a representative waste glass feed using both the simultaneous differential scanning calorimetry thermogravimetry (DSC-TGA) and the thermogravimetry coupled with gas chromatography-mass spectrometer (TGA-GC-MS) as complementary tools to perform evolved gas analysis (EGA). Analyses from DSC-TGA and EGA on the cold-cap reactions provide a key element for the development of an advanced cold-cap model. It also helps to formulate melter feeds for higher production rate.« less

Partial melting kinetics of plagioclase-diopside pairs

NASA Astrophysics Data System (ADS)

Tsuchiyama, Akira

1985-09-01

Partial melting experiments on plagioclase (An60) and diopside have been carried out using pairs of large crystals to investigate textures and kinetics of melting. The experiments were done at one atmosphere pressure as a function of temperature (1,190 1,307° C) and time (1.5 192 h). Melting took place mainly at the plagioclase-diopside contact planes. Reaction zones composed of fine mixtures of calcic plagioclase and melt were developed from the surface of the plagioclase crystal inward. There exists a critical temperature, below which only a few % melting can occur over the duration of the experiments. This sluggish melting is caused by slow NaSi-CaAl diffusion in plagioclase, because the plagioclase crystal must change its composition to produce albite-rich cotectic melts. Diffusion in the solid also affects the chemical composition of the melts. During initial melting, potassium is preferentially extracted from plagioclase because K-Na diffusion in plagioclase is faster than that of NaSi-CaAl. This also causes a shift in the cotectic compositions. Above the “critical temperature”, on the other hand, melting is promoted by a metastable reaction in which the plagioclase composition does not change, and which produces melts with compositional gradients along the original An60-diopside tie line. The critical temperature is determined by the intersection of the cotectic and the An60-diopside tie line. Interdiffusion coefficients of plagioclase-diopside components in the melt are estimated from melting rates above the critical temperature by using a simplified steady-state diffusion model (e.g., 10-8 cm2/sec at 1,300° C). Many examples of reaction zones due to partial melting have been described as spongy or fingerprint-like textures in xenoliths. Metastable melting above the critical temperature is considered to take place in natural melting where there is a high degree of melting. However, we cannot exclude the possibility of disequilibrium created by sluggish melting controlled by diffusion in the minerals. If melting occurs close to the solidus, this process can be important even for partial melting in the upper mantle.

Electrochemistry of Europium(III) Chloride in 3 LiCl – NaCl, 3 LiCl – 2 KCl, LiCl – RbCl, and 3 LiCl – 2 CsCl Eutectics at Various Temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schroll, Cynthia A.; Chatterjee, Sayandev; Levitskaia, Tatiana G.

Here we report the effect of changing the eutectic melt composition on the electrochemical properties of europium(III) chloride under pyroprocessing conditions. The number of electrons transferred, redox potentials and diffusion coefficients were determined using various electrochemical and spectroelectrochemical techniques in four different eutectic mixtures (3 LiCl - NaCl, 3 LiCl - 2 KCl, 3 LiCl - RbCl, and 3 LiCl - 2 CsCl) while varying the temperature of the melt. It was determined that Eu3+ undergoes a one electron reduction to Eu2+ in each melt at all temperatures evaluated. Within all the melts a positive shift in the redox potentialmore » as well as an increase in the diffusion coefficient for Eu3+ was observed as the temperature increased. Also observed was a positive shift in the redox potential and increase in the diffusion coefficient for Eu3+ as the weighted average of the cationic radii for the melt decreased.« less

Study of particle rearrangement, compression behavior and dissolution properties after melt dispersion of ibuprofen, Avicel and Aerosil

PubMed Central

Mallick, Subrata; Kumar Pradhan, Saroj; Chandran, Muronia; Acharya, Manoj; Digdarsini, Tanmayee; Mohapatra, Rajaram

2011-01-01

Particle rearrangements, compaction under pressure and in vitro dissolution have been evaluated after melt dispersion of ibuprofen, Avicel and Aerosil. The Cooper–Eaton and Kuno equations were utilized for the determination of particle rearrangement and compression behavior from tap density and compact data. Particle rearrangement could be divided into two stages as primary and secondary rearrangement. Transitional tapping between the stages was found to be 20–25 taps in ibuprofen crystalline powder, which was increased up to 45 taps with all formulated powders. Compaction in the rearrangement stages was increased in all the formulations with respect to pure ibuprofen. Significantly increased compaction of ibuprofen under pressure can be achieved using Avicel by melt dispersion technique, which could be beneficial in ibuprofen tablet manufacturing by direct compression. SEM, FTIR and DSC have been utilized for physicochemical characterization of the melt dispersion powder materials. Dissolution of ibuprofen from compacted tablet of physical mixture and melt dispersion particles has also been improved greatly in the following order: Ibc

Functional eladic containing triglycerides: Synthesis, physical properties, and solution behavior

USDA-ARS?s Scientific Manuscript database

The enthalpy of fusion (Hf) for a number of symmetrical and asymmetrical triacylgylcerides as mixtures in soybean oil (TAGs) were determined by melting point data (MPD), differential scanning calorimetry (DSC), and effective carbon numbers (ECN). Pure triacylgylcerides were mixed with soybean oil an...

Correlation between porosity and space holder content at different sintering temperatures of aluminum foam

NASA Astrophysics Data System (ADS)

Rushdi, N. M. F. M.; Jamaludin, S. B.; Mazlee, M. N.; Jamal, Z. A. Z.

2016-07-01

Aluminum foam is the most popular metal foam that can be used as energy absorbers, heat exchangers, air-oil separators and structure core of fuel cells. Melt-foaming agent, melt-gas injection, investment casting and powder-foaming agent techniques can be used to manufacture aluminum foam, but these techniques are too expensive. In this study, the aluminum foam was manufactured via a sintering dissolution process (SDP). Powders of aluminum and sodium chloride as space holder (25, 40, 50 wt. %) were mixed together to produce a homogeneous mixture. The mixture was compacted at 200 MPa followed by sintering at 500, 550 and 600˚C for 2 hours. A warm running water stream was used to dissolve the space holder that was embedded in the aluminum. The result showed that, the space holder content performed a significant role to control the total porosity to a value between 18 and 40%, and the porosity increased with increasing content of space holder and sintering temperature.

Viscosity of rock-ice mixtures and applications to the evolution of icy satellites

NASA Technical Reports Server (NTRS)

Friedson, A. J.; Stevenson, D. J.

1983-01-01

Theory and experiments are used to establish lower and upper bounds on the ratio of actual viscosity to pure ice viscosity for a suspension of rock particles in a water ice matrix. A rheological model for rock-ice mixtures is described, establishing bounds for the range of possible viscosity enhancements provided by a suspension of silicate spheres in an ice matrix. A parametrized thermal convection model is described and used to determine a criterion for criticality, defined as the heat flow and/or silicate volume fraction for which the satellite temperature profile intercepts the melting curve of water ice. The consequences of achieving this critical state are examined, and it is shown that under certain circumstances a 'runaway' differentiation can occur in which the silicates settle to form a core and extensive melting of water ice takes place, the latent heat being supplied by the gravitational energy of differentiation. A possible application of these results to Ganymede and Callisto is described.

The impact of dispersion on selective laser melting of titanium and niobium fine powders mixture

NASA Astrophysics Data System (ADS)

Razin, A.; Ovchinnikov, V.; Akhmetshin, R.; Krinitcyn, M.; Fedorov, V.; Akhmetshina, V.

2016-11-01

This paper is dedicated to the study of selective laser melting process of metal powders. Experiments were performed in the Research Center Modern Manufacturing Technologies of TPU with the fine powders of titanium and niobium. The research was carried out on 3D laser printer designed at TPU. In the framework of experiments aimed at determining possibilities of obtaining niobium-titanium alloy by SLS (selective laser sintering) there were studied the basic processes of laser melting and their effect on the quality of final samples and products. We determined operation modes of 3D printers which allow obtaining high quality of printed sample surface. The research results show that rigid requirements related to powder dispersiveness and proportions are needed to achieve better quality of products.

Modified T-history method for measuring thermophysical properties of phase change materials at high temperature

NASA Astrophysics Data System (ADS)

Omaraa, Ehsan; Saman, Wasim; Bruno, Frank; Liu, Ming

2017-06-01

Latent heat storage using phase change materials (PCMs) can be used to store large amounts of energy in a narrow temperature difference during phase transition. The thermophysical properties of PCMs such as latent heat, specific heat and melting and solidification temperature need to be defined at high precision for the design and estimating the cost of latent heat storage systems. The existing laboratory standard methods, such as differential thermal analysis (DTA) and differential scanning calorimetry (DSC), use a small sample size (1-10 mg) to measure thermophysical properties, which makes these methods suitable for homogeneous elements. In addition, this small amount of sample has different thermophysical properties when compared with the bulk sample and may have limitations for evaluating the properties of mixtures. To avoid the drawbacks in existing methods, the temperature - history (T-history) method can be used with bulk quantities of PCM salt mixtures to characterize PCMs. This paper presents a modified T-history setup, which was designed and built at the University of South Australia to measure the melting point, heat of fusion, specific heat, degree of supercooling and phase separation of salt mixtures for a temperature range between 200 °C and 400 °C. Sodium Nitrate (NaNO3) was used to verify the accuracy of the new setup.

Ammonia-water mixtures at high pressures - Melting curves of ammonia dihydrate and ammonia monohydrate and a revised high-pressure phase diagram for the water-rich region. [in primordial solar system ices

NASA Technical Reports Server (NTRS)

Boone, S.; Nicol, M. F.

1991-01-01

The phase relations of some mixtures of ammonia and water are investigated to create a phase diagram in pressure-temperature-composition space relevant to the geophysical study of bodies in the outer solar system. The mixtures of NH3(x)H2O(1-x), where x is greater than 0.30 but less than 0.51, are examined at pressures and temperatures ranging from 0-6.5 GPa and 125-400 K, respectively. The ruby luminescence technique monitors the pressure and a diamond-anvil cell compresses the samples, and the phases are identified by means of normal- and polarized-light optical microscopy. The melting curve for NH3H2O(2) is described by the equation T = 176 + 60P - 8.5P squared for the ranges of 0.06-1.4 GPa and 179-243 K. The equation for NH3H2O is T = 194 + 37P - P squared, which represents a minor correction of a previous description by Johnson et al. (1985). Observed phase transitions are consistent with the high-pressure stability limit of NH3H2O(2), and the transition boundary is found to be linear.

Rheology Guided Rational Selection of Processing Temperature To Prepare Copovidone-Nifedipine Amorphous Solid Dispersions via Hot Melt Extrusion (HME).

PubMed

Yang, Fengyuan; Su, Yongchao; Zhang, Jingtao; DiNunzio, James; Leone, Anthony; Huang, Chengbin; Brown, Chad D

2016-10-03

The production of amorphous solid dispersions via hot melt extrusion (HME) relies on elevated temperature and prolonged residence time, which can result in potential degradation and decomposition of thermally sensitive components. Herein, the rheological properties of a physical mixture of polymer and an active pharmaceutical ingredient (API) were utilized to guide the selection of appropriate HME processing temperature. In the currently studied copovidone-nifedipine system, a critical temperature, which is substantially lower (∼13 °C) than the melting point of crystalline API, was captured during a temperature ramp examination and regarded as the critical point at which the API could molecularly dissolve into the polymer. Based on the identification of this critical point, various solid dispersions were prepared by HME processing below, at, and above the critical temperature (both below and above the melting temperature (T m ) of crystalline API). In addition, the resultant extrudates along with two control solid dispersions prepared by physical mixing and cryogenic milling were assessed by X-ray diffraction, differential scanning calorimetry, hot stage microscopy, rheology, and solid-state NMR. Physicochemical properties of resultant solid dispersions indicated that the identified critical temperature is sufficient for the polymer-API system to reach a molecular-level mixing, manifested by the transparent and smooth appearance of extrudates, the absence of API crystalline diffraction and melting peaks, dramatically decreased rheological properties, and significantly improved polymer-API miscibility. Once the critical temperature has been achieved, further raising the processing temperature only results in limited improvement of API dispersion, reflected by slightly reduced storage modulus and complex viscosity and limited improvement in miscibility.

A dearth of intermediate melts at subduction zone volcanoes and the petrogenesis of arc andesites.

PubMed

Reubi, Olivier; Blundy, Jon

2009-10-29

Andesites represent a large proportion of the magmas erupted at continental arc volcanoes and are regarded as a major component in the formation of continental crust. Andesite petrogenesis is therefore fundamental in terms of both volcanic hazard and differentiation of the Earth. Andesites typically contain a significant proportion of crystals showing disequilibrium petrographic characteristics indicative of mixing or mingling between silicic and mafic magmas, which fuels a long-standing debate regarding the significance of these processes in andesite petrogenesis and ultimately questions the abundance of true liquids with andesitic composition. Central to this debate is the distinction between liquids (or melts) and magmas, mixtures of liquids with crystals, which may or may not be co-genetic. With this distinction comes the realization that bulk-rock chemical analyses of petrologically complex andesites can lead to a blurred picture of the fundamental processes behind arc magmatism. Here we present an alternative view of andesite petrogenesis, based on a review of quenched glassy melt inclusions trapped in phenocrysts, whole-rock chemistry, and high-pressure and high-temperature experiments. We argue that true liquids of intermediate composition (59 to 66 wt% SiO(2)) are far less common in the sub-volcanic reservoirs of arc volcanoes than is suggested by the abundance of erupted magma within this compositional range. Effective mingling within upper crustal magmatic reservoirs obscures a compositional bimodality of melts ascending from the lower crust, and masks the fundamental role of silicic melts (>/=66 wt% SiO(2)) beneath intermediate arc volcanoes. This alternative view resolves several puzzling aspects of arc volcanism and provides important clues to the integration of plutonic and volcanic records.

Low melting high lithia glass compositions and methods

DOEpatents

Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

2004-11-02

The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

Low melting high lithia glass compositions and methods

DOEpatents

Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

2003-10-07

The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

Low melting high lithia glass compositions and methods

DOEpatents

Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

2000-01-01

The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

Methods of vitrifying waste with low melting high lithia glass compositions

DOEpatents

Jantzen, Carol M.; Pickett, John B.; Cicero-Herman, Connie A.; Marra, James C.

2001-01-01

The invention relates to methods of vitrifying waste and for lowering the melting point of glass forming systems by including lithia formers in the glass forming composition in significant amounts, typically from about 0.16 wt % to about 11 wt %, based on the total glass forming oxides. The lithia is typically included as a replacement for alkali oxide glass formers that would normally be present in a particular glass forming system. Replacement can occur on a mole percent or weight percent basis, and typically results in a composition wherein lithia forms about 10 wt % to about 100 wt % of the alkali oxide glass formers present in the composition. The present invention also relates to the high lithia glass compositions formed by these methods. The invention is useful for stabilization of numerous types of waste materials, including aqueous waste streams, sludge solids, mixtures of aqueous supernate and sludge solids, combinations of spent filter aids from waste water treatment and waste sludges, supernate alone, incinerator ash, incinerator offgas blowdown, or combinations thereof, geological mine tailings and sludges, asbestos, inorganic filter media, cement waste forms in need of remediation, spent or partially spent ion exchange resins or zeolites, contaminated soils, lead paint, etc. The decrease in melting point achieved by the present invention desirably prevents volatilization of hazardous or radioactive species during vitrification.

Temperature and Time Constraints on Dissolution, Fe-Mg Exchange and Zoning between Relict Forsterite and Chondrule Melt - Implications for Thermal History of Chondrules

NASA Astrophysics Data System (ADS)

Ustunisik, G. K.; Ebel, D. S. S.; Walker, D.

2016-12-01

The chemical and textural characteristics of different generations of relict olivine grains in chondrules record the fact that chondrules were re-melted. Mineral dissolution, Fe-Mg exchange, and zoning within the relict crystals constrain the T-t aspects of this re-melting process. Here, we performed isothermal and dynamic cooling experiments at LDEO of Columbia University. For each run, a cubic crystal of known dimensions of Mogok forsterite (Fo99) was placed in synthetic Type IIA chondrule mesostasis with 4.92 wt% FeO (TLiq 1315ºC). Pressed pellets of this mixture were hung on Pt-wire loops and inserted in vertical Deltech furnace where CO-CO2 gas mixtures kept fO2 IW-1. For isothermal experiments, each charge was heated to 1428ºC, 1350ºC, 1250ºC, and 1150ºC and was held there from 20 mins to several days (>3 days) before drop-quenching into cold water. The dynamic crystallization experiments were held at 1428ºC for 20 mins, cooled at rates of 75ºC, 722ºC, and 1444ºC/hr to 1000ºC and then water quenched. X-ray-CT and EMPA at AMNH were used to image the partially resorbed/zoned olivines in 3-D before and after each run to observe textural evolution of the crystal shapes and volumes and to determine chemical changes. The isothermal experiments at 1150 and 1250ºC for 20 mins, produced no bulk FeO diffusion into the Mogok forsterite. Very minor Fe-Mg exchange at the crystal rims gives slight MgO zoning within the nearby melt. With increasing duration (1 hr and 22 hrs), at 1250ºC, embayments of melt form into the rims of the crystal (amplified at 22 hrs) with significant Fe-Mg exchange. FeO content of Mogok increased with major MgO zonation within nearby melt. At 1150ºC, the same increase in FeO in Mogok and zonation in nearby glass could only be achieved in >3 days experiment. At high Ts (1428ºC) in 20 min run, 75 volume % of Mogok forsterite has been dissolved into the melt. Resorption erodes the Fe-Mg exchange at the rims of the crystal. At longer duration experiments (1250ºC, 22 hrs and 1150ºC, >3days) quench olivine crystals and silica (cristobalite) have been observed within the melt along with low-Ca pyroxene along the edges of the Mogok forsterite. The metastable pyroxene acts as a protective cover thwarting Fe-Mg exchange between Mogok and Fe-bearing melt. The cristobalite occurred as a result of melt fractionation.

Radioactive-gas separation technique

NASA Technical Reports Server (NTRS)

Haney, R.; King, K. J.; Nellis, D. O.; Nisson, R. S.; Robling, P.; Womack, W.

1977-01-01

Cryogenic technique recovers gases inexpensively. Method uses differences in vapor pressures, melting points, and boiling points of components in gaseous mixture. Series of temperature and pressure variations converts gases independently to solid and liquid states, thereby simplifying separation. Apparatus uses readily available cryogen and does not require expensive refrigeration equipment.

Formation of the racemic compound of ephedrine base from a physical mixture of its enantiomers in the solid, liquid, solution, or vapor state.

PubMed

Duddu, S P; Grant, D J

1992-08-01

Physical mixtures (conglomerates) of the two enantiomers of ephedrine base, each containing 0.5% (w/w) of water, were observed to be converted to the 1:1 racemic compound in the solid, liquid, solution, or vapor state. From a geometrically mixed racemic conglomerate of particle size 250-300 microns (50-60 mesh), the formation of the racemic compound follows second-order kinetics (first order with respect to each enantiomer), with a rate constant of 392 mol-1 hr-1 at 22 degrees C. The reaction appears to proceed via the vapor phase as indicated by the growth of the crystals of the racemic compound between diametrically separated crystals of the two enantiomers in a glass petri dish. The observed kinetics of conversion in the solid state are explained by a homogeneous reaction model via the vapor and/or liquid states. Formation of the racemic compound from the crystals of ephedrine enantiomers in the solution state may explain why Schmidt et al. (Pharm. Res. 5:391-395, 1988) observed a consistently lower aqueous solubility of the mixture than of the pure enantiomers. The solid phase in equilibrium with the solution at the end of the experiment was found to be the racemic compound, whose melting point and heat of fusion are higher than those of the enantiomers. An association reaction, of measurable rate, between the opposite enantiomers in a binary mixture in the solid, liquid, solution, or vapor state to form the racemic compound may be more common than is generally realized.

Electrically conductive containment vessel for molten aluminum

DOEpatents

Holcombe, C.E.; Scott, D.G.

1984-06-25

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal 10 borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Electrically conductive containment vessel for molten aluminum

DOEpatents

Holcombe, Cressie E.; Scott, Donald G.

1985-01-01

The present invention is directed to a containment vessel which is particularly useful in melting aluminum. The vessel of the present invention is a multilayered vessel characterized by being electrically conductive, essentially nonwettable by and nonreactive with molten aluminum. The vessel is formed by coating a tantalum substrate of a suitable configuration with a mixture of yttria and particulate metal borides. The yttria in the coating inhibits the wetting of the coating while the boride particulate material provides the electrical conductivity through the vessel. The vessel of the present invention is particularly suitable for use in melting aluminum by ion bombardment.

Method for locating metallic nitride inclusions in metallic alloy ingots

DOEpatents

White, Jack C.; Traut, Davis E.; Oden, Laurance L.; Schmitt, Roman A.

1992-01-01

A method of determining the location and history of metallic nitride and/or oxynitride inclusions in metallic melts. The method includes the steps of labeling metallic nitride and/or oxynitride inclusions by making a coreduced metallic-hafnium sponge from a mixture of hafnium chloride and the chloride of a metal, reducing the mixed chlorides with magnesium, nitriding the hafnium-labeled metallic-hafnium sponge, and seeding the sponge to be melted with hafnium-labeled nitride inclusions. The ingots are neutron activated and the hafnium is located by radiometric means. Hafnium possesses exactly the proper metallurgical and radiochemical properties for this use.

Low temperature double-layer capacitors

NASA Technical Reports Server (NTRS)

Brandon, Erik J. (Inventor); West, William C. (Inventor); Smart, Marshall C. (Inventor)

2011-01-01

Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -75.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. An optimized concentration (e.g., 0.10 M to 0.75 M) of salt, such as tetraethylammonium tetrafluoroborate, is dissolved into the electrolyte solution. In some cases (e.g., 1,3-dioxolane cosolvent) additives, such as 2% by volume triethylamine, may be included in the solvent mixture to prevent polymerization of the solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed.

Investigating the oxidation mechanism of tantalum nanoparticles at high heating rates

NASA Astrophysics Data System (ADS)

DeLisio, Jeffery B.; Wang, Xizheng; Wu, Tao; Egan, Garth C.; Jacob, Rohit J.; Zachariah, Michael R.

2017-12-01

Reduced diffusion length scales and increased specific surface areas of nanosized metal fuels have recently demonstrated increased reaction rates for these systems, increasing their relevance in a wide variety of applications. The most commonly employed metal fuel, aluminum, tends to oxidize rapidly near its melting point (660 °C) in addition to undergoing a phase change of the nascent oxide shell. To further expand on the understanding of nanosized metal fuel oxidation, tantalum nanoparticles were studied due to their high melting point (3017 °C) in comparison to aluminum. Both traditional slow heating rate and in-situ high heating rate techniques were used to probe the oxidation of tantalum nanoparticles in oxygen containing environments in addition to nanothermite mixtures. When oxidized by gas phase oxygen, the oxide shell of the tantalum nanoparticles rapidly crystallized creating cracks that may attribute to enhanced oxygen diffusion into the particle. In the case of tantalum based nanothermites, oxide shell crystallization was shown to induce reactive sintering with the metal oxide resulting in a narrow range of ignition temperatures independent of the metal oxide used. The oxidation mechanism was modeled using the Deal-Grove model to extract rate parameters, and theoretical burn times for tantalum based nanocomposites were calculated.

Combinatorial synthesis of phosphors using arc-imaging furnace

PubMed Central

Ishigaki, Tadashi; Toda, Kenji; Yoshimura, Masahiro; Uematsu, Kazuyoshi; Sato, Mineo

2011-01-01

We have applied a novel ‘melt synthesis technique’ rather than a conventional solid-state reaction to rapidly synthesize phosphor materials. During a synthesis, the mixture of oxides or their precursors is melted by light pulses (10–60 s) in an arc-imaging furnace on a water-cooled copper hearth to form a globule of 1–5 mm diameter, which is then rapidly cooled by turning off the light. Using this method, we synthesized several phosphor compounds including Y3Al5O12:Ce(YAG) and SrAl2O4:Eu,Dy. Complex phosphor oxides are difficult to produce by conventional solid-state reaction techniques because of the slow reaction rates among solid oxides; as a result, the oxides form homogeneous compounds or solid solutions. On the other hand, melt reactions are very fast (10–60 s) and result in homogeneous compounds owing to rapid diffusion and mixing in the liquid phase. Therefore, melt synthesis techniques are suitable for preparing multi component homogeneous compounds and solid solutions. PMID:27877432

Combinatorial synthesis of phosphors using arc-imaging furnace

NASA Astrophysics Data System (ADS)

Ishigaki, Tadashi; Toda, Kenji; Yoshimura, Masahiro; Uematsu, Kazuyoshi; Sato, Mineo

2011-10-01

We have applied a novel 'melt synthesis technique' rather than a conventional solid-state reaction to rapidly synthesize phosphor materials. During a synthesis, the mixture of oxides or their precursors is melted by light pulses (10-60 s) in an arc-imaging furnace on a water-cooled copper hearth to form a globule of 1-5 mm diameter, which is then rapidly cooled by turning off the light. Using this method, we synthesized several phosphor compounds including Y3Al5O12:Ce(YAG) and SrAl2O4:Eu,Dy. Complex phosphor oxides are difficult to produce by conventional solid-state reaction techniques because of the slow reaction rates among solid oxides; as a result, the oxides form homogeneous compounds or solid solutions. On the other hand, melt reactions are very fast (10-60 s) and result in homogeneous compounds owing to rapid diffusion and mixing in the liquid phase. Therefore, melt synthesis techniques are suitable for preparing multi component homogeneous compounds and solid solutions.

Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 to 1400 K

NASA Technical Reports Server (NTRS)

Misra, Ajay K.; Whittenberger, J. Daniel

1987-01-01

Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

Fluoride salts and container materials for thermal energy storage applications in the temperature range 973 - 1400 K

NASA Technical Reports Server (NTRS)

Misra, Ajay K.; Whittenberger, J. Daniel

1987-01-01

Multicomponent fluoride salt mixtures were characterized for use as latent heat of fusion heat storage materials in advanced solar dynamic space power systems with operating temperatures in the range of 973 to 1400 K. The melting points and eutectic composition for many systems with published phase diagrams were verified, and several new eutectic compositions were identified. Additionally, the heats of fusion of several binary and ternary eutectics and congruently melting intermediate compounds were measured by differential scanning calorimetry. The extent of corrosion of various metals by fluoride melts was estimated from thermodynamic considerations, and equilibrium conditions inside a containment vessel were calculated as functions of the initial moisture content of the salt and free volume above the molten salt. Preliminary experimental data on the corrosion of commercial, high-temperature alloys in LiF-19.5CaF2 and NaF-27CaF2-36MgF2 melts are presented and compared to the thermodynamic predictions.

Ash fusion characteristics during co-gasification of biomass and petroleum coke.

PubMed

Xiong, Qing-An; Li, Jiazhou; Guo, Shuai; Li, Guang; Zhao, Jiantao; Fang, Yitian

2018-06-01

In this study, the effect of biomass ash on petroleum coke ash fusibility was investigated at a reducing atmosphere. Some analytical methods, such as ash fusion temperatures (AFTs) analysis, X-ray diffraction (XRD), FactSage and scanning electron microscopy (SEM), were applied to determine the characteristics of ash fusion and transformation of mineral matters. The results indicated that AFTs were closely associated with ash mineral compositions. It was found that the formations of high melting point calcium silicate, vanadium trioxide and coulsonite resulted in the high AFTs of Yanqing petroleum coke (YQ). When blending with certain proportional pine sawdust (PS), corn stalk (CS), the AFTs of mixture could be decreased significantly. For PS addition, the formations of low-melting point calcium vanadium oxide should be responsible for the reduction of AFTs, whereas for CS addition the reason was ascribed to the formation of low-melting point leucite and the disappearance of high-melting V 2 O 3 . Copyright © 2018. Published by Elsevier Ltd.

Geochemistry of Intra-Transform Lavas from the Galápagos Transform Fault

NASA Astrophysics Data System (ADS)

Morrow, T. A.; Mittelstaedt, E. L.; Harpp, K. S.

2013-12-01

The Galápagos plume has profoundly affected the development and evolution of the nearby (<250 km) Galápagos Transform Fault (GTF), a ~100km right-stepping offset in the Galápagos Spreading Center (GSC). The GTF can be divided into two sections that represent different stages of transform evolution: the northern section exhibits fully developed transform fault morphology, whereas the southern section is young, and deformation is more diffuse. Both segments are faulted extensively and include numerous small (<0.5km3) monogenetic volcanic cones, though volcanic activity is more common in the south. To examine the composition of the mantle source and melting conditions responsible for the intra-transform lavas, as well as the influence of the plume on GTF evolution, we present major element, trace element, and radiogenic isotope analysis of samples collected during SON0158, EWI0004, and MV1007 cruises. Radiogenic isotope ratio variations in the Galápagos Archipelago require four distinct mantle reservoirs across the region: PLUME, DM, FLO, and WD. We find that Galápagos Transform lavas are chemically distinct from nearby GSC lavas and neighboring seamounts. They have radiogenic isotopic compositions that lie on a mixing line between DM and PLUME, with little to no contribution from any other mantle reservoirs despite their geographic proximity to WD-influenced lavas erupted along the GSC and at nearby (<50km away) seamounts. Within the transform, lavas from the northern section are more enriched in radiogenic isotopes than lavas sampled in the southern section. Transform lavas are anomalously depleted in incompatible trace elements (ITEs) relative to GSC lavas, suggesting unique melting conditions within the transform. Isotopic variability along the transform axis indicates that mantle sources and/or melting mechanisms vary between the northern and southern sections, which may relate to their distances from the plume or the two-stage development and evolution of the Galápagos Transform Fault. We present a melting model that reproduces GTF lava chemistry from a mixture of two partial melts of PLUME and DM. We assume that the DM source has an ITE composition similar to the depleted upper mantle, melting is purely fractional, and lavas do not fractionate during ascent. Solutions were achieved using a Metropolis algorithm and constrained by observed GTF lava chemistry. Model results predict that GTF lavas are produced by a mixture of a ~3%×1% partial melt of the PLUME source and a ~5%×4% partial melt of the DM source. Our model predicts that a larger proportion of PLUME melts contribute to GTF lavas than DM melts. Absence of the WD component and relatively low concentrations of ITEs may indicate that lavas in the GTF are produced from a source that has already undergone partial melting and is being re-melted beneath the TF. Re-melting may be caused by extension across the GTF, or development of the southern section of the GTF via the ~1Ma ridge jump.

Chemistry of Tertiary sediments in the surroundings of the Ries impact structure and moldavite formation revisited

NASA Astrophysics Data System (ADS)

Žák, Karel; Skála, Roman; Řanda, Zdeněk; Mizera, Jiří; Heissig, Kurt; Ackerman, Lukáš; Ďurišová, Jana; Jonášová, Šárka; Kameník, Jan; Magna, Tomáš

2016-04-01

Moldavites, tektites of the Central European strewn field, have been traditionally linked with the Ries impact structure in Germany. They are supposed to be derived mainly from the near-surface sediments of the Upper Freshwater Molasse of Miocene age that probably covered the target area before the impact. Comparison of the chemical composition of moldavites with that of inferred source materials requires recalculation of the composition of sediments to their water-, organic carbon- and carbon dioxide-free residuum. This recalculation reflects the fact that these compounds were lost almost completely from the target materials during their transformation to moldavites. Strong depletions in concentrations of many elements in moldavites relative to the source sediments (e.g., Mo, Cu, Ag, Sb, As, Fe) contrast with enrichments of several elements in moldavites (e.g., Cs, Ba, K, Rb). These discrepancies can be generally solved using two different approaches, either by involvement of a component of specific chemical composition, or by considering elemental fractionation during tektite formation. The proposed conceptual model of moldavite formation combines both approaches and is based on several steps: (i) the parent mixture (Upper Freshwater Molasse sediments as the dominant source) contained also a minor admixture of organic matter and soils; (ii) the most energetic part of the ejected matter was converted to vapor (plasma) and another part produced melt directly upon decompression; (iii) following further adiabatic decompression, the expanding vapor phase disintegrated the melt into small melt droplets and some elements were partially lost from the melt because of their volatility, or because of the volatility of their compounds, such as carbonyls of Fe and other transition metals (e.g., Ni, Co, Mo, Cr, and Cu); (iv) large positively charged ions such as Cs+, Ba2+, K+, Rb+ from the plasma portion were enriched in the late-stage condensation spherules or condensed directly onto negatively charged melt droplets; (v) simultaneously, the melt droplets coalesced into larger tektite bodies. Steps (iii)-(v) may have overlapped in time. The still melted moldavite bodies reaching their final size were reshaped by further melt flow. This melt flow was related to moldavite rotation and escape (bubbling off) of the last portion of gaseous volatiles during their flight in a low-pressure region above the dense layer of the atmosphere.

Investigation of the noble gas solubility in H 2O-CO 2 bearing silicate liquids at moderate pressure II: the extended ionic porosity (EIP) model

NASA Astrophysics Data System (ADS)

Nuccio, P. M.; Paonita, A.

2000-12-01

A semi-theoretical model is proposed to predict partitioning of noble gases between any silicate liquid and a H 2O-CO 2 gas phase with noble gas as a minor component, in a large range of pressures (at least up to 300 MPa). The model is based on the relationship between the concentration of dissolved noble gas and ionic porosity of the melt, found by Carroll and Stolper [Geochim. Cosmochim. Acta 57 (1993) 5039-5051] for H 2O-CO 2 free melts. It evaluates the effect of dissolved H 2O and CO 2 on the melt ionic porosity and, consequently on Henry's constants of noble gases. The fugacities of the noble gases in the H 2O-CO 2-noble gas mixtures are also considered in our equilibrium calculations of dissolved gas by using a modified Redlich-Kwong equation of state for the H 2O-CO 2-noble gas system. The formulated model (referred to as the extended ionic porosity model) clearly predicts a positive dependence of noble gas solubility on dissolved H 2O in melt, which becomes negligible when water concentration is higher than 3 wt%. Oppositely, noble gas solubility decreases as a consequence of increasing CO 2 in both basaltic and rhyolitic melts. The increase of noble gas solubility as a consequence of H 2O addition to the melt grows exponentially with the increase of the noble gas atomic size. As a result, although xenon solubility is much lower than the helium solubility in anhydrous melts, they become almost comparable at several percent of dissolved H 2O in the melt. On this basis, an exponential augmentation of the number of large free spaces in silicate liquid can be inferred in relation to increasing dissolved H 2O. Comparison between our predicted values and available experimental data [A. Paonita et al., Earth Planet. Sci. Lett. 181 (2000) 595-604] shows good agreement. At present, the EIP model is the unique tool which predicts how the main volatiles in magmatic systems affect the noble gas solubility in silicate melts, therefore it should be taken into account for future studies of noble gas fractionation in degassing natural magmas.

Redox properties of samarium, europium and ytterbium in molten eutectic mixture of sodium, potassium and cesium chlorides

NASA Astrophysics Data System (ADS)

Golovanova, O. A.; Tropin, O. A.; Volkovich, V. A.

2017-09-01

The redox behavior of samarium, europium and ytterbium ions was investigated in the ternary 6NaCl-9KCl- 5CsCl eutectic based melts between 823 and 1073 K employing cyclic voltammetry on a tungsten working electrode. Ln(II)/Ln(III) (Ln=Sm, Eu, Yb) reduction-oxidation is reversible and controlled by diffusion of the electroactive species at the potential scan rates up to 0.1 V/s. Formal standard redox potentials E*Ln(II)/Ln(III) were determined, and the thermodynamic and transport properties of the corresponding Ln(III) and Ln(II) ions were estimated.

Process for utilizing low-cost graphite substrates for polycrystalline solar cells

NASA Technical Reports Server (NTRS)

Chu, T. L. (Inventor)

1978-01-01

Low cost polycrystalline silicon solar cells supported on substrates were prepared by depositing successive layers of polycrystalline silicon containing appropriate dopants over supporting substrates of a member selected from the group consisting of metallurgical grade polycrystalline silicon, graphite and steel coated with a diffusion barrier of silica, borosilicate, phosphosilicate, or mixtures thereof such that p-n junction devices were formed which effectively convert solar energy to electrical energy. To improve the conversion efficiency of the polycrystalline silicon solar cells, the crystallite size in the silicon was substantially increased by melting and solidifying a base layer of polycrystalline silicon before depositing the layers which form the p-n junction.

40 CFR 98.140 - Definition of the source category.

Code of Federal Regulations, 2011 CFR

2011-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.140 Definition of the source category. (a) A glass manufacturing facility manufactures flat glass, container glass, pressed and blown glass, or wool fiberglass by melting a mixture of raw materials to produce molten glass and form the molten...

40 CFR 98.140 - Definition of the source category.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Glass Production § 98.140 Definition of the source category. (a) A glass manufacturing facility manufactures flat glass, container glass, pressed and blown glass, or wool fiberglass by melting a mixture of raw materials to produce molten glass and form the molten...

Process to create simulated lunar agglutinate particles

NASA Technical Reports Server (NTRS)

Gustafson, Robert J. (Inventor); Gustafson, Marty A. (Inventor); White, Brant C. (Inventor)

2011-01-01

A method of creating simulated agglutinate particles by applying a heat source sufficient to partially melt a raw material is provided. The raw material is preferably any lunar soil simulant, crushed mineral, mixture of crushed minerals, or similar material, and the heat source creates localized heating of the raw material.

21 CFR 172.886 - Petroleum wax.

Code of Federal Regulations, 2010 CFR

2010-04-01

... availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register... it is very hygroscopic and will react with some metal containers in the presence of air. Phosphoric... high enough to keep the wax melted. (Note: In preheating the sulfoxide-acid mixture, remove the stopper...

Reactive sintering of ceramic lithium ion electrolyte membranes

DOEpatents

Badding, Michael Edward; Dutta, Indrajit; Iyer, Sriram Rangarajan; Kent, Brian Alan; Lonnroth, Nadja Teresia

2017-06-06

Disclosed herein are methods for making a solid lithium ion electrolyte membrane, the methods comprising combining a first reactant chosen from amorphous, glassy, or low melting temperature solid reactants with a second reactant chosen from refractory oxides to form a mixture; heating the mixture to a first temperature to form a homogenized composite, wherein the first temperature is between a glass transition temperature of the first reactant and a crystallization onset temperature of the mixture; milling the homogenized composite to form homogenized particles; casting the homogenized particles to form a green body; and sintering the green body at a second temperature to form a solid membrane. Solid lithium ion electrolyte membranes manufactured according to these methods are also disclosed herein.

Methods for achieving the equilibrium number of phases in mixtures suitable for use in battery electrodes, e.g., for lithiating FeS.sub.2

DOEpatents

Guidotti, Ronald A.

1988-01-01

In a method for preparing lithiated, particulate FeS.sub.2 useful as a catholyte material in a lithium thermal battery, whereby the latter's voltage regulation properties are improved, comprising admixing FeS.sub.2 and an amount of a lithium-containing compound whereby the resultant total composition falls in an invariant region of the metallurgical phase diagram of its constituent components, an improvement comprises admixing said lithium-containing compound and FeS.sub.2 together with a solid electrolyte compatible with said catholyte, and heating the mixture at a temperature above the melting point of said electrolyte and at which said mixture reaches its thermodynamic equilibrium number of phases.

Pore Formation and Mobility Investigation (PPMI): Description and Initial Analysis of Experiments Conducted aboard the International Space Station

NASA Technical Reports Server (NTRS)

Grugel, R. N.; Anilkumar, A. V.; Lee, C. P.

2003-01-01

Flow visualization experiments during the controlled directional melt back and re-solidification of succinonitrile (SCN) and SCN-water mixtures were conducted using the Pore Formation and Mobility Investigation (PFMI) apparatus in the glovebox facility (GBX) aboard the International Space Station. The study samples were initially 'cast' on earth under 450 millibar of nitrogen into 1 cm ID glass sample tubes approximately 30 cm in length, containing 6 in situ thermocouples. During the Space experiments, the processing parameters and flow visualization settings are remotely monitored and manipulated from the ground Telescience Center (TSC). The ground solidified sample is first subjected to a unidirectional melt back, generally at 10 microns per second, with a constant temperature gradient ahead of the melting interface. Bubbles of different sizes are seen to initiate at the melt interface and, upon release from the melting solid, translate at different speeds in the temperature field ahead of them before coming to rest. Over a period of time these bubbles dissolve into the melt. The gas-laden liquid is then directionally solidified in a controlled manner, generally starting at a rate of 1 micron /sec. Observation and preliminary analysis of bubble formation and mobility in pure SCN samples during melt back and the subsequent structure resulting during gas generation upon re-solidification are presented and discussed.

Pore Formation and Mobility Investigation (PFMI): Description and Initial Analysis of Experiments Conducted aboard the International Space Station

NASA Technical Reports Server (NTRS)

Grugel, R. N.; Anilkumar, A. V.; Lee, C. P.

2002-01-01

Flow visualization experiments during the controlled directional melt back and re-solidification of succinonitrile (SCN) and SCN-water mixtures were conducted using the Pore Formation and Mobility Investigation (PFMI) apparatus in the glovebox facility (GBX) aboard the International Space Station. The study samples were initially "cast" on earth under 450 millibar of nitrogen into 1 cm ID glass sample tubes approximately 30 cm in length, containing 6 in situ thermocouples. During the Space experiments, the processing parameters and flow visualization settings are remotely monitored and manipulated from the ground Telescience Center (TSC). The ground solidified sample is first subjected to a unidirectional melt back, generally at 10 microns per second, with a constant temperature gradient ahead of the melting interface. Bubbles of different sizes are seen to initiate at the melt interface and, upon release from the melting solid, translate at different speeds in the temperature field ahead of them before coming to rest. Over a period of time these bubbles dissolve into the melt. The gas-laden liquid is then directionally solidified in a controlled manner, generally starting at a rate of 1 micron /sec. Observation and preliminary analysis of bubble formation and mobility in pure SCN samples during melt back and the subsequent structure resulting during gas generation upon re-solidification are presented and discussed.

On the preparation of TiAl alloy by direct reduction of the oxide mixtures in calcium chloride melt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prabhat K. Tripathy; Derek J. Fray

2011-11-01

In recent years, TiAl-based intermetallic alloys are being increasingly considered for application in areas such as (i) automobile/transport sector (passenger cars, trucks and ships) (ii) aerospace industry (jet engines and High Speed Civil Transport propulsion system) and (iii) industrial gas turbines. These materials offer excellent (i) high temperature properties (at higher than 6000C) (ii) mechanical strength and (iii) resistance to corrosion and as a result have raised renewed interest. The combination of these properties make them possible replacement materials for traditional nickel-based super-alloys, which are nearly as twice as dense (than TiAl based alloys). Since the microstructures of these intermetallicmore » alloys affect, to a significant extent, their ultimate performance, further improvements (by way of alteration/modification of these microstructures), have been the subject matter of intense research investigations. It has now been established that the presence of alloy additives, such as niobium, tantalum, manganese, boron, chromium, silicon, nickel and yttrium etc, in specific quantities, impart marked improvement to the properties, viz. fatigue strength, fracture toughness, oxidation resistance and room temperature ductility, of these alloys. From a number of possible alloy compositions, {gamma}-TiAl and Ti-Al-Nb-Cr have, of late, emerged as two promising engineering alloys/materials. . The conventional fabrication process of these alloys include steps such as melting, forging and heat treatment/annealing of the alloy compositions. However, an electrochemical process offers an attractive proposition to prepare these alloys, directly from the mixture of the respective oxides, in just one step. The experimental approach, in this new process, was, therefore, to try to electrochemically reduce the (mixed) oxide pellet to an alloy phase. The removal of oxygen, from the (mixed) oxide pellet, was effected by polarizing the oxide pellet against a graphite electrode in a pool of molten calcium chloride at a temperature of 9000C. The dominant mechanism of the oxygen removal was the ionization of oxygen followed by its subsequent discharge, as CO2/CO, at the anode surface. The removal of oxygen from the oxide mixture helped form the alloy in situ. The presentation shall cover the detailed experimental results pertaining to the preparation, evaluation and characterization of Ti-47Al-2Nb-2Cr (atom%) alloy.« less

Feasibility study on development of metal matrix composite by microwave stir casting

NASA Astrophysics Data System (ADS)

Lingappa, S. M.; Srinath, M. S.; Amarendra, H. J.

2018-04-01

Need for better service oriented materials has boosted the demand for metal matrix composite materials, which can be developed to have necessary properties. One of the most widely utilized metal matrix composite is Al-SiC, which is having a matrix made of aluminium metal and SiC as reinforcement. Lightweight and conductivity of aluminium, when combined with hardness and wear resistance of SiC provides an excellent platform for various applications in the field of electronics, automotives, and aerospace and so on. However, uniform distribution of reinforcement particles is an issue and has to be addressed. The present study is an attempt made to develop Al-SiC metal matrix composite by melting base metal using microwave hybrid heating technique, followed by addition of reinforcement and stirring the mixture for obtaining homogenous mixture. X-Ray Diffraction analysis shows the presence of aluminium and SiC in the cast material. Further, microstructural study shows the distribution of SiC particles in the grain boundaries.

MARMOT Phase-Field Model for the U-Si System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aagesen, Larry Kenneth; Schwen, Daniel

2016-09-01

A phase-field model for the U-Si system has been implemented in MARMOT. The free energies for the phases relevant to accident-tolerant fuel applications (U 3Si 2, USi, U 3Si, and liquid) were implemented as free energy materials within MARMOT. A new three-phase phase-field model based on the concepts of the Kim-Kim-Suzuki two-phase model was developed and implemented in the MOOSE phase-field module. Key features of this model are that two-phase interfaces are stable with respect to formation of the third phase, and that arbitrary phase free energies can be used. The model was validated using a simplified three-phase system andmore » the U-Si system. In the U-Si system, the model correctly reproduced three-phase coexistence in a U 3Si 2-liquid-USi system at the eutectic temperature, solidification of a three-phase mixture below the eutectic temperature, and complete melting of a three-phase mixture above the eutectic temperature.« less

Molecular dynamics of acetamide based ionic deep eutectic solvents

NASA Astrophysics Data System (ADS)

Srinivasan, H.; Dubey, P. S.; Sharma, V. K.; Biswas, R.; Mitra, S.; Mukhopadhyay, R.

2018-04-01

Deep eutectic solvents are multi-component mixtures that have freezing point lower than their individual components. Mixture of acetamide+ lithium nitrate in the molar ratio 78:22 and acetamide+ lithium perchlorate in the molar ratio 81:19 are found to form deep eutectic solvents with melting point lower than the room temperature. It is known that the depression in freezing point is due to the hydrogen bond breaking ability of anions in the system. Quasielastic neutron scattering experiments on these systems were carried out to study the dynamics of acetamide molecules which may be influenced by this hydrogen bond breaking phenomena. The motion of acetamide molecules is modeled using jump diffusion mechanism to demonstrate continuous breaking and reforming hydrogen bonds in the solvent. Using the jump diffusion model, it is inferred that the jump lengths of acetamide molecules are better approximated by a Gaussian distribution. The shorter residence time of acetamide in presence of perchlorate ions suggest that the perchlorate ions have a higher hydrogen bond breaking ability compared to nitrate ions.

The Effect of Fe-Ti-rich Cumulate Overturn on Evolution of the Lunar Interior

NASA Astrophysics Data System (ADS)

Mallik, A.; Ejaz, T.; Shcheka, S.; Garapic, G.; Petitgirard, S.; Blanchard, I.

2017-12-01

The last 5% of magma ocean crystallized Fe-Ti rich cumulates (FTC) emplaced below the anorthitic crust [1]. Due to gravitational instability, FTC underwent diapiric downwelling [2], associated with overturn of the lunar mantle. Petrological studies on Apollo basalts with variable TiO2 place their sources between 1.5-3 GPa. This indicates the presence of heterogeneous Ti-rich domains in the lunar interior which could either be produced by inefficient overturn and mixing [3], or due to post-overturn upwelling of FTC from the core-mantle boundary (CMB) [4]. Also, a seismically attenuating layer at the CMB ( 4.5 GPa) maybe associated with partial melt of overturned FTC [5]. Thus, it is important to investigate the phase equilibria of FTC with and without assimilation with the surrounding mantle, to understand better the effect of the overturn process on lunar evolution. We performed phase equilibria experiments at 2 and 4.5 GPa, 1230 to 1700 °C using a multi-anvil apparatus on FTC and a 1:1 mixture of FTC and mantle composition. FTC produced Fe-Ti rich (FeO 13-26 wt.%, TiO2 11-18 wt.%), Mg-poor (MgO 6-10 wt.%) basalts with residues of clinopyroxene+quartz+Fe-metal±spinel, while the mixture of FTC and mantle produced Fe-Ti-Mg rich (FeO 10-13 wt.%, TiO2 5-11 wt.% and MgO 20-30 wt.%) basalts with residues of orthopyroxene+olivine+Fe-metal±spinel±garnet. We find that partial melting of overturned cumulates within the lunar mantle can reproduce certain chemical attributes of Apollo high Ti basalts. Also, to test whether the partial melt of overturned cumulates can be stable at the CMB to produce the attenuating layer, we estimated the densities of these melt compositions using the published range of KT and K' of high Fe-Ti picrites. We find that the densities obtained from the published spread in K' and KT values yield inconclusive results about the stability of these partial melts at the CMB. This is being resolved by in-situ experimental determination of the densities of the high Fe-Ti melt compositions, currently underway. If these partial melts are indeed stable at the CMB, they bracket the present-day CMB temperature between 1300-1490 °C (5 to 30% partial melting [5]).[1] Snyder et al. (1992), GCA [2] Hess & Permentier (1995), EPSL [3] Brown & Grove (2015), GCA [4] Zhong et al. (2000), EPSL [5] Weber et al. (2011), Science

The thermodynamic activity of ZnO in silicate melts

NASA Astrophysics Data System (ADS)

Reyes, R. A.; Gaskell, D. R.

1983-12-01

The activity of ZnO in ZnO-SiO2 and CaO-ZnO-SiO2 melts has been measured at 1560 °C using a transpiration technique with CO-CO2 mixtures as the carrier gas. The activities of ZnO in dilute solution in 42 wt pct SiO2-38 wt pct CaO-20 wt pct A12O3 in the range 1400° to 1550 °C and in 62 wt pct SiO2-23.3 wt pct CaO-14.7 wt pct A12O3 at 1550 °C have also been measured. The measured free energies of formation of ZnO-SiO2 melts are significantly more negative than published estimated values and this, together with the behavior observed in the system CaO-Al2O3-SiO2, indicate that ZnO is a relatively basic oxide. The results are discussed in terms of the polymerization model of binary silicate melts and ideal silicate mixing in ternary silicate melts. The behavior of ZnO in dilute solution in CaO-Al2O3-SiO2 melts is discussed in terms of the possibility of the fluxing of ZnO by iron blast furnace slags.

Experimental evidence supports mantle partial melting in the asthenosphere.

PubMed

Chantel, Julien; Manthilake, Geeth; Andrault, Denis; Novella, Davide; Yu, Tony; Wang, Yanbin

2016-05-01

The low-velocity zone (LVZ) is a persistent seismic feature in a broad range of geological contexts. It coincides in depth with the asthenosphere, a mantle region of lowered viscosity that may be essential to enabling plate motions. The LVZ has been proposed to originate from either partial melting or a change in the rheological properties of solid mantle minerals. The two scenarios imply drastically distinct physical and geochemical states, leading to fundamentally different conclusions on the dynamics of plate tectonics. We report in situ ultrasonic velocity measurements on a series of partially molten samples, composed of mixtures of olivine plus 0.1 to 4.0 volume % of basalt, under conditions relevant to the LVZ. Our measurements provide direct compressional (V P) and shear (V S) wave velocities and constrain attenuation as a function of melt fraction. Mantle partial melting appears to be a viable origin for the LVZ, for melt fractions as low as ~0.2%. In contrast, the presence of volatile elements appears necessary to explaining the extremely high V P/V S values observed in some local areas. The presence of melt in LVZ could play a major role in the dynamics of plate tectonics, favoring the decoupling of the plate relative to the asthenosphere.

Novel Molten Salts Thermal Energy Storage for Concentrating Solar Power Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, Ramana G.

2013-10-23

The explicit UA program objective is to develop low melting point (LMP) molten salt thermal energy storage media with high thermal energy storage density for sensible heat storage systems. The novel Low Melting Point (LMP) molten salts are targeted to have the following characteristics: 1. Lower melting point (MP) compared to current salts (<222ºC) 2. Higher energy density compared to current salts (>300 MJ/m3) 3. Lower power generation cost compared to current salt In terms of lower power costs, the program target the DOE's Solar Energy Technologies Program year 2020 goal to create systems that have the potential to reducemore » the cost of Thermal Energy Storage (TES) to less than $15/kWh-th and achieve round trip efficiencies greater than 93%. The project has completed the experimental investigations to determine the thermo-physical, long term thermal stability properties of the LMP molten salts and also corrosion studies of stainless steel in the candidate LMP molten salts. Heat transfer and fluid dynamics modeling have been conducted to identify heat transfer geometry and relative costs for TES systems that would utilize the primary LMP molten salt candidates. The project also proposes heat transfer geometry with relevant modifications to suit the usage of our molten salts as thermal energy storage and heat transfer fluids. The essential properties of the down-selected novel LMP molten salts to be considered for thermal storage in solar energy applications were experimentally determined, including melting point, heat capacity, thermal stability, density, viscosity, thermal conductivity, vapor pressure, and corrosion resistance of SS 316. The thermodynamic modeling was conducted to determine potential high temperature stable molten salt mixtures that have thermal stability up to 1000 °C. The thermo-physical properties of select potential high temperature stable (HMP) molten salt mixtures were also experimentally determined. All the salt mixtures align with the go/no-go goals stipulated by the DOE for this project. Energy densities of all salt mixtures were higher than that of the current solar salt. The salt mixtures costs have been estimated and TES system costs for a 2 tank, direct approach have been estimated for each of these materials. All estimated costs are significantly below the baseline system that used solar salt. These lower melt point salts offer significantly higher energy density per volume than solar salt – and therefore attractively smaller inventory and equipment costs. Moreover, a new TES system geometry has been recommended A variety of approaches were evaluated to use the low melting point molten salt. Two novel changes are recommended that 1) use the salt as a HTF through the solar trough field, and 2) use the salt to not only create steam but also to preheat the condensed feedwater for Rankine cycle. The two changes enable the powerblock to operate at 500°C, rather than the current 400°C obtainable using oil as the HTF. Secondly, the use of salt to preheat the feedwater eliminates the need to extract steam from the low pressure turbine for that purpose. Together, these changes result in a dramatic 63% reduction required for 6 hour salt inventory, a 72% reduction in storage volume, and a 24% reduction in steam flow rate in the power block. Round trip efficiency for the Case 5 - 2 tank “direct” system is estimated at >97%, with only small losses from time under storage and heat exchange, and meeting RFP goals. This attractive efficiency is available because the major heat loss experienced in a 2 tank “indirect” system - losses by transferring the thermal energy from oil HTF to the salt storage material and back to oil to run the steam generator at night - is not present for the 2 tank direct system. The higher heat capacity values for both LMP and HMP systems enable larger storage capacities for concentrating solar power.« less

Melt-gas phase equilibria and state diagrams of the selenium-tellurium system

NASA Astrophysics Data System (ADS)

Volodin, V. N.; Trebukhov, S. A.; Burabaeva, N. M.; Nitsenko, A. V.

2017-05-01

The partial pressures of saturated vapor of the components in the Se-Te system are determined and presented in the form of temperature-concentration dependences from which the boundaries of the melt-gas phase transition are calculated at atmospheric pressure and vacuums of 2000 and 100 Pa. The existence of azeotropic mixtures is revealed. It is found that the points of inseparably boiling melts correspond to 7.5 at % of Se and 995°C at 101325 Pa, 10.9 at % at 673°C and 19.5 at % at 522°C in vacuums of 2000 and 100 Pa, respectively. A complete state diagram is constructed, including the fields of gas-liquid equilibria at atmospheric and low pressures, the boundaries of which allow us to assess the behavior of selenium and tellurium upon distillation fractionation.

On the phase evolution of AlCoCrCuFeMnSix high entropy alloys prepared by mechanical alloying and arc melting route

NASA Astrophysics Data System (ADS)

Kumar, Anil; Chopkar, Manoj

2018-05-01

Effect of Si addition on phase formation of AlCoCrCuFeMnSix (x=0, 0.3, 0.6 and 0.9) high entropy alloy have been investigated in this work. The alloys are prepared by mechanical alloying and vacuum arc melting technique. The X-ray diffraction results reveals the formation of mixture of face centered and body centered cubic solid solution phases in milled powders. The addition of Si favours body centered cubic structure formation during milling process. Whereas, after melting the milled powders, body centered phases formed during milling is partial transformed into sigma phases. XRD results were also correlated with the SEM elemental mapping of as casted samples. Addition of Si favours σ phase formation in the as cast samples.

Hot melt extrusion versus spray drying: hot melt extrusion degrades albendazole.

PubMed

Hengsawas Surasarang, Soraya; Keen, Justin M; Huang, Siyuan; Zhang, Feng; McGinity, James W; Williams, Robert O

2017-05-01

The purpose of this study was to enhance the dissolution properties of albendazole (ABZ) by the use of amorphous solid dispersions. Phase diagrams of ABZ-polymer binary mixtures generated from Flory-Huggins theory were used to assess miscibility and processability. Forced degradation studies showed that ABZ degraded upon exposure to hydrogen peroxide and 1 N NaOH at 80 °C for 5 min, and the degradants were albendazole sulfoxide (ABZSX), and ABZ impurity A, respectively. ABZ was chemically stable following exposure to 1 N HCl at 80 °C for one hour. Thermal degradation profiles show that ABZ, with and without Kollidon ® VA 64, degraded at 180 °C and 140 °C, respectively, which indicated that ABZ could likely be processed by thermal processing. Following hot melt extrusion, ABZ degraded up to 97.4%, while the amorphous ABZ solid dispersion was successfully prepared by spray drying. Spray-dried ABZ formulations using various types of acids (methanesulfonic acid, sulfuric acid and hydrochloric acid) and polymers (Kollidon ® VA 64, Soluplus ® and Eudragit ® E PO) were studied. The spray-dried ABZ with methanesulfonic acid and Kollidon ® VA 64 substantially improved non-sink dissolution in acidic media as compared to bulk ABZ (8-fold), physical mixture of ABZ:Kollidon ® VA 64 (5.6-fold) and ABZ mesylate salt (1.6-fold). No degradation was observed in the spray-dried product for up to six months and less than 5% after one-year storage. In conclusion, amorphous ABZ solid dispersions in combination with an acid and polymer can be prepared by spray drying to enhance dissolution and shelf-stability, whereas those made by melt extrusion are degraded.

Flash Points of Secondary Alcohol and n-Alkane Mixtures.

PubMed

Esina, Zoya N; Miroshnikov, Alexander M; Korchuganova, Margarita R

2015-11-19

The flash point is one of the most important characteristics used to assess the ignition hazard of mixtures of flammable liquids. To determine the flash points of mixtures of secondary alcohols with n-alkanes, it is necessary to calculate the activity coefficients. In this paper, we use a model that allows us to obtain enthalpy of fusion and enthalpy of vaporization data of the pure components to calculate the liquid-solid equilibrium (LSE) and vapor-liquid equilibrium (VLE). Enthalpy of fusion and enthalpy of vaporization data of secondary alcohols in the literature are limited; thus, the prediction of these characteristics was performed using the method of thermodynamic similarity. Additionally, the empirical models provided the critical temperatures and boiling temperatures of the secondary alcohols. The modeled melting enthalpy and enthalpy of vaporization as well as the calculated LSE and VLE flash points were determined for the secondary alcohol and n-alkane mixtures.

Methods for Melting Temperature Calculation

NASA Astrophysics Data System (ADS)

Hong, Qi-Jun

Melting temperature calculation has important applications in the theoretical study of phase diagrams and computational materials screenings. In this thesis, we present two new methods, i.e., the improved Widom's particle insertion method and the small-cell coexistence method, which we developed in order to capture melting temperatures both accurately and quickly. We propose a scheme that drastically improves the efficiency of Widom's particle insertion method by efficiently sampling cavities while calculating the integrals providing the chemical potentials of a physical system. This idea enables us to calculate chemical potentials of liquids directly from first-principles without the help of any reference system, which is necessary in the commonly used thermodynamic integration method. As an example, we apply our scheme, combined with the density functional formalism, to the calculation of the chemical potential of liquid copper. The calculated chemical potential is further used to locate the melting temperature. The calculated results closely agree with experiments. We propose the small-cell coexistence method based on the statistical analysis of small-size coexistence MD simulations. It eliminates the risk of a metastable superheated solid in the fast-heating method, while also significantly reducing the computer cost relative to the traditional large-scale coexistence method. Using empirical potentials, we validate the method and systematically study the finite-size effect on the calculated melting points. The method converges to the exact result in the limit of a large system size. An accuracy within 100 K in melting temperature is usually achieved when the simulation contains more than 100 atoms. DFT examples of Tantalum, high-pressure Sodium, and ionic material NaCl are shown to demonstrate the accuracy and flexibility of the method in its practical applications. The method serves as a promising approach for large-scale automated material screening in which the melting temperature is a design criterion. We present in detail two examples of refractory materials. First, we demonstrate how key material properties that provide guidance in the design of refractory materials can be accurately determined via ab initio thermodynamic calculations in conjunction with experimental techniques based on synchrotron X-ray diffraction and thermal analysis under laser-heated aerodynamic levitation. The properties considered include melting point, heat of fusion, heat capacity, thermal expansion coefficients, thermal stability, and sublattice disordering, as illustrated in a motivating example of lanthanum zirconate (La2Zr2O7). The close agreement with experiment in the known but structurally complex compound La2Zr 2O7 provides good indication that the computation methods described can be used within a computational screening framework to identify novel refractory materials. Second, we report an extensive investigation into the melting temperatures of the Hf-C and Hf-Ta-C systems using ab initio calculations. With melting points above 4000 K, hafnium carbide (HfC) and tantalum carbide (TaC) are among the most refractory binary compounds known to date. Their mixture, with a general formula TaxHf 1-xCy, is known to have a melting point of 4215 K at the composition Ta4HfC 5, which has long been considered as the highest melting temperature for any solid. Very few measurements of melting point in tantalum and hafnium carbides have been documented, because of the obvious experimental difficulties at extreme temperatures. The investigation lets us identify three major chemical factors that contribute to the high melting temperatures. Based on these three factors, we propose and explore a new class of materials, which, according to our ab initio calculations, may possess even higher melting temperatures than Ta-Hf-C. This example also demonstrates the feasibility of materials screening and discovery via ab initio calculations for the optimization of "higher-level" properties whose determination requires extensive sampling of atomic configuration space.

General baseline toxicity QSAR for nonpolar, polar and ionisable chemicals and their mixtures in the bioluminescence inhibition assay with Aliivibrio fischeri.

PubMed

Escher, Beate I; Baumer, Andreas; Bittermann, Kai; Henneberger, Luise; König, Maria; Kühnert, Christin; Klüver, Nils

2017-03-22

The Microtox assay, a bioluminescence inhibition assay with the marine bacterium Aliivibrio fischeri, is one of the most popular bioassays for assessing the cytotoxicity of organic chemicals, mixtures and environmental samples. Most environmental chemicals act as baseline toxicants in this short-term screening assay, which is typically run with only 30 min of exposure duration. Numerous Quantitative Structure-Activity Relationships (QSARs) exist for the Microtox assay for nonpolar and polar narcosis. However, typical water pollutants, which have highly diverse structures covering a wide range of hydrophobicity and speciation from neutral to anionic and cationic, are often outside the applicability domain of these QSARs. To include all types of environmentally relevant organic pollutants we developed a general baseline toxicity QSAR using liposome-water distribution ratios as descriptors. Previous limitations in availability of experimental liposome-water partition constants were overcome by reliable prediction models based on polyparameter linear free energy relationships for neutral chemicals and the COSMOmic model for charged chemicals. With this QSAR and targeted mixture experiments we could demonstrate that ionisable chemicals fall in the applicability domain. Most investigated water pollutants acted as baseline toxicants in this bioassay, with the few outliers identified as uncouplers or reactive toxicants. The main limitation of the Microtox assay is that chemicals with a high melting point and/or high hydrophobicity were outside of the applicability domain because of their low water solubility. We quantitatively derived a solubility cut-off but also demonstrated with mixture experiments that chemicals inactive on their own can contribute to mixture toxicity, which is highly relevant for complex environmental mixtures, where these chemicals may be present at concentrations below the solubility cut-off.

Crustal Anatexis by Upwelling Mantle Melts in the N.Atlantic Igneous Province: the Isle of Rum, NW Scotland.

NASA Astrophysics Data System (ADS)

Hertogen, J.; Meyer, R.; Nicoll, G.; Troll, V. R.; Ellam, R. M.; Emeleus, C. H.

2008-12-01

Crustal anatexis is a common process in the rift-to-drift evolution during continental breakup and the formation of Volcanic Rifted Margins (VRM) systems. 'Early felsic-later mafic' volcanic rock associations on the Continent Ocean Boundary (COB) of the N.Atlantic Ocean have been sampled by ODP drilling on the SE Greenland margin and the the Vøring Plateau (Norwegian Sea). Such associations also occur further inland in the British Paleocene Igneous Province, such as on the Isle of Rum (e.g., Troll et al., Contrib. Min. Petrol., 2004, 147, p.722). Sr and Nd isotope and trace element geochemistry show that the Rum rhyodacites are the products of melting of Lewisian amphibolite gneiss. There are no indications of a melt contribution from Lewisian granulite gneiss. The amphibolite gneiss parent rock had experienced an ancient Cs and Rb loss, possibly during a Caledonian event, which caused 87Sr/86Sr heterogeneity in the crustal source of silicic melts. The dacites and early gabbros of Rum are mixtures of crustal melts and primary mantle melts. Rare Earth Element modelling shows that late stage picritic melts on Rum are close analogues for the parent melts of the Rum Layered Suite, and for the mantle melts that caused crustal anatexis of the Lewisian gneiss. These primary mantle melts have close affinities to MORB whose trace element content varies from slightly depleted to slightly enriched. The 'early felsic-later mafic' volcanic associations from Rum, and from the now drowned seaward dipping wedges on the shelf of SE Greenland and on the Vøring Plateau show geochemical differences that result from variations in the regional crustal composition and the depth at which crustal anatexis took place.

Petrology and geochemistry of the Tasse mantle xenoliths of the Canadian Cordillera: A record of Archean to Quaternary mantle growth, metasomatism, removal, and melting

NASA Astrophysics Data System (ADS)

Polat, Ali; Frei, Robert; Longstaffe, Fred J.; Thorkelson, Derek J.; Friedman, Eyal

2018-07-01

Mantle xenoliths hosted by the Quaternary Tasse alkaline basalts in the Canadian Cordillera, southeastern British Columbia, are mostly spinel lherzolite originating from subcontinental lithospheric mantle. The xenoliths contain abundant feldspar veins, melt pockets and spongy clinopyroxene, recording extensive alkaline metasomatism and partial melting. Feldspar occurs as veins and interstitial crystal in melt pockets. Melt pockets occur mainly at triple junctions, along grain boundaries, and consist mainly of olivine, cpx, opx and spinel surrounded by interstitial feldspar. The Nd, Sr and Pb isotopic compositions of the xenoliths indicate that their sources are characterized by variable mixtures of depleted MORB mantle and EM1 and EM2 mantle components. Large variations in εNd values (-8.2 to +9.6) and Nd depleted mantle model ages (TDM = 66 to 3380 Ma) are consistent with multiple sources and melt extraction events, and long-term (>3300 Ma) isolation of some source regions from the convecting mantle. Samples with Archean and Paleoproterozoic Nd model ages are interpreted as either have been derived from relict Laurentian mantle pieces beneath the Cordillera or have been eroded from the root of the Laurentian craton to the east and transported to the base of the Cordilleran lithosphere by edge-driven convection currents. The oxygen isotope compositions of the xenoliths (average δ18O = +5.1 ± 0.5‰) are similar to those of depleted mantle. The average δ18O values of olivine (+5.0 ± 0.2‰), opx (+5.9 ± 0.6‰), cpx (+6.0 ± 0.6‰) and spinel (+4.5 ± 0.2‰) are similar to mantle values. Large fractionations for olivine-opx, olivine-cpx and opx-cpx pairs, however, reflect disequilibrium stemming from metasomatism and partial melting. Whole-rock trace element, Nd, Sr, Pb and O isotope compositions of the xenoliths and host alkaline basalts indicate different mantle sources for these two suites of rocks. The xenoliths were derived from shallow lithospheric sources, whereas the alkaline basalts originated from a deeper asthenospheric mantle source.

Continuous Preparation of 1:1 Haloperidol-Maleic Acid Salt by a Novel Solvent-Free Method Using a Twin Screw Melt Extruder.

PubMed

Lee, Hung Lin; Vasoya, Jaydip M; Cirqueira, Marilia de Lima; Yeh, Kuan Lin; Lee, Tu; Serajuddin, Abu T M

2017-04-03

Salts are generally prepared by acid-base reaction in relatively large volumes of organic solvents, followed by crystallization. In this study, the potential for preparing a pharmaceutical salt between haloperidol and maleic acid by a novel solvent-free method using a twin-screw melt extruder was investigated. The pH-solubility relationship between haloperidol and maleic acid in aqueous medium was first determined, which demonstrated that 1:1 salt formation between them was feasible (pH max 4.8; salt solubility 4.7 mg/mL). Extrusion of a 1:1 mixture of haloperidol and maleic acid at the extruder barrel temperature of 60 °C resulted in the formation of a highly crystalline salt. The effects of operating temperature and screw configuration on salt formation were also investigated, and those two were identified as key processing parameters. Salts were also prepared by solution crystallization from ethyl acetate, liquid-assisted grinding, and heat-assisted grinding and compared with those obtained by melt extrusion by using DSC, PXRD, TGA, and optical microscopy. While similar salts were obtained by all methods, both melt extrusion and solution crystallization yielded highly crystalline materials with identical enthalpies of melting. During the pH-solubility study, a salt hydrate form was also identified, which, upon heating, converted to anhydrate similar to that obtained by other methods. There were previous reports of the formation of cocrystals, but not salts, by melt extrusion. 1 H NMR and single-crystal X-ray diffraction confirmed that a salt was indeed formed in the present study. The haloperidol-maleic acid salt obtained was nonhygroscopic in the moisture sorption study and converted to the hydrate form only upon mixing with water. Thus, we are reporting for the first time a relatively simple and solvent-free twin-screw melt extrusion method for the preparation of a pharmaceutical salt that provides material comparable to that obtained by solution crystallization and is amenable to continuous manufacturing and easy scale up.

Preparation of glass-ceramics from molten steel slag using liquid-liquid mixing method.

PubMed

Zhang, Kai; Liu, Jianwen; Liu, Wanchao; Yang, Jiakuan

2011-10-01

A novel approach to prepare glass-ceramics from molten steel slag (MSS) was proposed. In laboratory, the water-quenched steel slag was melted at 1350 °C to simulate the MSS. A mixture of additive powders in wt.% (55 quartz powder, 5 Na2O, 16 emery powder, 15 CaO, 8 MgO, 1 TiO2) were melted into liquid at 1350 °C separately. Then the MSS and the molten additives were mixed homogeneously in order to obtain parent glass melt. The proportion of MSS in the melt was 50 wt.%. The melt was subsequently cast, annealed, heat-treated and transformed into glass-ceramics. Their microstructure and crystallization behavior were analyzed. The samples exhibited excellent properties and displayed bulk crystallization. The major crystallized phase was diopside ((Fe0.35Al0.20Mg0.44)Ca0.96(Fe0.08Si0.70Al0.20)2O6.12), which was uniformly distributed in the microstructure. The novel approach may help iron and steel industry achieve zero disposal of steel slag with utilization of the heat energy of the MSS. Copyright © 2011 Elsevier Ltd. All rights reserved.

Application of carrier and plasticizer to improve the dissolution and bioavailability of poorly water-soluble baicalein by hot melt extrusion.

PubMed

Zhang, Yilan; Luo, Rui; Chen, Yi; Ke, Xue; Hu, Danrong; Han, Miaomiao

2014-06-01

The objective of this study was to develop a suitable formulation for baicalein (a poorly water-soluble drug exhibiting high melting point) to prepare solid dispersions using hot melt extrusion (HME). Proper carriers and plasticizers were selected by calculating the Hansen solubility parameters, evaluating melting processing condition, and measuring the solubility of obtained melts. The characteristic of solid dispersions prepared by HME was evaluated. The dissolution performance of the extrudates was compared to the pure drug and the physical mixtures. Physicochemical properties of the extrudates were characterized by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR). Relative bioavailability after oral administration in beagle dogs was assessed. As a result, Kollidon VA64 and Eudragit EPO were selected as two carriers; Cremophor RH was used as the plasticizer. The dissolution of all the extrudates was significantly improved. DSC and PXRD results suggested that baicalein in the extrudates was amorphous. FTIR spectroscopy revealed the interaction between drug and polymers. After oral administration, the relative bioavailability of solid dispersions with VA64 and EPO was comparative, about 2.4- and 2.9-fold greater compared to the pure drug, respectively.

Method and apparatus for reducing mixed waste

DOEpatents

Elliott, Michael L.; Perez, Jr., Joseph M.; Chapman, Chris C.; Peters, Richard D.

1995-01-01

The present invention is a method and apparatus for in-can waste reduction. The method is mixing waste with combustible material prior to placing the waste into a waste reduction vessel. The combustible portion is ignited, thereby reducing combustible material to ash and non-combustible material to a slag. Further combustion or heating may be used to sinter or melt the ash. The apparatus is a waste reduction vessel having receiving canister connection means on a first end, and a waste/combustible mixture inlet on a second end. An oxygen supply is provided to support combustion of the combustible mixture.

Ice shelf melt rates in Greenland and Antarctica using time-tagged digital imagery from World View and TanDEM-X

NASA Astrophysics Data System (ADS)

Charolais, A.; Rignot, E. J.; Milillo, P.; Scheuchl, B.; Mouginot, J.

2017-12-01

The floating extensions of glaciers, or ice shelves, melt vigorously in contact with ocean waters. Melt is non uniform, with the highest melt taking place in the deepest part of the cavity, where thermal forcing is the greatest because of 1) the pressure dependence of the freezing point of the seawater/ice mixture and 2) subglacial water injects fresh, buoyant, cold melt water to fuel stronger ice-ocean interactions. Melt also forms along preferential channels, which are not stationary, and create lines of weakness in the shelf. Ice shelf melt rates have been successfully measured from space over the entire Antarctic continent and on the ice shelves in Greenland using an Eulerian approach that combines ice thickness, ice velocity vectors, surface mass balance data, and measurements of ice thinning rates. The Eulerian approach is limited by the precision of the thickness gradients, typically of a few km, and requires significant spatial averaging to remove advection effects. A Lagrangian approach has been shown to be robust to advection effects and provides higher resolution details. We implemented a Lagrangian methodology for time-tagged World View DEMs by the Polar Geoscience Center (PGS) at the University of Minnesota and time-tagged TanDEM-X DEMs separated by one year. We derive melt rates on a 300-m grid with a precision of a few m/yr. Melt is strongest along grounding lines and along preferred channels. Channels are non-stationary because melt is not the same on opposite sides of the channels. Examining time series of data and comparing with the time-dependent grounding line positions inferred from satellite radar interferometry, we evaluate the magnitude of melt near the grounding line and even within the grounding zone. A non-zero melt rate in the grounding zone has vast implications for ice sheet modeling. This work is funded by a grant from NASA Cryosphere Program.

Research study for gel precursors as glass and ceramic starting materials for space processing applications research

NASA Technical Reports Server (NTRS)

Downs, R. L.; Miller, W. J.

1983-01-01

The development of techniques for the preparation of glass and ceramic starting materials that will result in homogeneous glasses or ceramic products when melted and cooled in a containerless environment is described. Metal-organic starting materials were used to make compounds or mixtures which were then decomposed by hydrolysis reactions to the corresponding oxides. The sodium tungstate system was chosen as a model for a glass with a relatively low melting temperature. The alkoxide tungstates also have interesting optical properties. For all the compositions studied, comparison samples were prepared from inorganic starting materials and submitted to the same analyses.

Cellular Precipitates Of Iron Oxide in Olivine in a Stratospheric Interplanetary Dust Particle

NASA Technical Reports Server (NTRS)

Rietmeijer, Frans J. M.

1996-01-01

The petrology of a massive olivine-sulphide interplanetary dust particle shows melting of Fe,Ni-sulphide plus complete loss of sulphur and subsequent quenching to a mixture of iron-oxides and Fe,Ni-metal. Oxidation of the fayalite component in olivine produced maghemite discs and cellular intergrowths with olivine and rare andradite-rich garnet. Cellular reactions require no long-range solid-state diffusion and are kinetically favourable during pyrometamorphic oxidation. Local melting of the cellular intergrowths resulted in three dimensional symplectic textures. Dynamic pyrometamorphism of this asteroidal particle occurred at approx. 1100 C during atmospheric entry flash (5-15 s) heating.

Low-melting point heat transfer fluid

DOEpatents

Cordaro, Joseph G [Oakland, CA; Bradshaw, Robert W [Livermore, CA

2011-04-12

A low-melting point, heat transfer fluid comprising a mixture of LiNO.sub.3, NaNO.sub.3, KNO.sub.3, NaNO.sub.2 and KNO.sub.2 salts where the Li, Na and K cations are present in amounts of about 20-33.5 mol % Li, about 18.6-40 mol % Na, and about 40-50.3 mol % K and where the nitrate and nitrite anions are present in amounts of about 36-50 mol % NO.sub.3, and about 50-62.5 mol % NO.sub.2. These compositions can have liquidus temperatures between 70.degree. C. and 80.degree. C. for some compositions.

The Nature of C Asteroid Regolith Revealed from the Jbilet Winselwan CM Chondrite

NASA Technical Reports Server (NTRS)

Zolensky, Michael; Mikouchi, Takashi; Hagiya, Kenji; Ohsumi, Kazumasa; Komatsu, Mutsumi; Chan, Queenie H. S.; Le, Loan; Kring, David; Cato, Michael; Fagan, Amy L.

2016-01-01

C-class asteroids frequently exhibit reflectance spectra consistent with thermally metamorphosed carbonaceous chondrites, or a mixture of phyllosilicate-rich material along with regions where they are absent. One particularly important example appears to be asteroid 162173 Ryugu, the target of the Hayabusa 2 mission, although most spectra of Ryugu are featureless, suggesting a heterogeneous regolith. Here we explore an alternative cause of dehydration of regolith of C-class asteroids - impact shock melting. Impact shock melting has been proposed to ex-plain some mineralogical characteristics of CB chondrites, but has rarely been considered a major process for hydrous carbonaceous chondrites.

21 CFR 172.830 - Succinylated monoglycerides.

Code of Federal Regulations, 2010 CFR

2010-04-01

... of glycerol with edible fat-forming fatty acids. (b) The additive meets the following specifications: Succinic acid content: 14.8%-25.6% Melting point: 50 °C-60 °C. Acid number: 70-120 (c) The additive is used... additive is a mixture of semi-and neutral succinic acid esters of mono- and diglycerides produced by the...

Influence of convection on microstructure

NASA Technical Reports Server (NTRS)

Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

1990-01-01

The mechanism responsible for the difference in microstructure caused by solidifying the MnBi-Bi eutectic in space is sought. The objectives for the three year period are as follows: (1) completion of the following theoretical analyses - determination of the influence of the Soret effect on the average solid composition versus distance of off-eutectic mixtures directionally solidified in the absence of convection, determination of the influence of convection on the microstructure of off-eutectic mixtures using a linear velocity profile in the adjacent melt, determination of the influence of volumetric changes during solidification on microconvection near the freezing interface and on microstructure, and determination of the influence of convection on microstructure when the MnBi fibers project out in front of the bismuth matrix; (2) search for patterns in the effect of microgravity on different eutectics (for example, eutectic composition, eutectic temperature, usual microstructure, densities of pure constituents, and density changes upon solidification); and (3) determination of the Soret coefficient and the diffusion coefficient for Mn-Bi melts near the eutectic composition, both through laboratory experiements to be performed here and from data from Shuttle experiments.

Dielectric constant of liquid alkanes and hydrocarbon mixtures

NASA Technical Reports Server (NTRS)

Sen, A. D.; Anicich, V. G.; Arakelian, T.

1992-01-01

The complex dielectric constants of n-alkanes with two to seven carbon atoms have been measured. The measurements were conducted using a slotted-line technique at 1.2 GHz and at atmospheric pressure. The temperature was varied from the melting point to the boiling point of the respective alkanes. The real part of the dielectric constant was found to decrease with increasing temperature and correlate with the change in the molar volume. An upper limit to all the loss tangents was established at 0.001. The complex dielectric constants of a few mixtures of liquid alkanes were also measured at room temperature. For a pentane-octane mixture the real part of the dielectric constant could be explained by the Clausius-Mosotti theory. For the mixtures of n-hexane-ethylacetate and n-hexane-acetone the real part of the dielectric constants could be explained by the Onsager theory extended to mixtures. The dielectric constant of the n-hexane-acetone mixture displayed deviations from the Onsager theory at the highest fractions of acetone. The dipole moments of ethylacetate and acetone were determined for dilute mixtures using the Onsager theory and were found to be in agreement with their accepted gas-phase values. The loss tangents of the mixtures exhibited a linear relationship with the volume fraction for low concentrations of the polar liquids.

Slate Islands, Lake Superior, Canada: A mid-size, Complex Impact Structure

NASA Technical Reports Server (NTRS)

Dressler, B. O.; Sharpton, V. L.; Copeland, P.

1999-01-01

The target rocks of the 30-32-km diameter Slate Islands impact structure in northern Lake Superior, Canada, are Archean supracrustal and igneous rocks and supracrustal Proterozoic rocks. Shatter cones, pseudotachylites, impact glasses, and microscopic shock metamorphic features were formed during the contact and compression phase of the impact process, followed, during excavation and central uplift, by polymict, clastic matrix breccias in the uplifted target, and by allogenic fall-back breccias (suevite and bunte breccia). Monomict, autoclastic breccias were mainly observed on Mortimer Island and the other outlying islands of the archipelago and were probably generated relatively late in the impact process (central uplift and/or crater modification). The frequency of low index planar shock metamorphic features in quartz was correlated with results from shock experiments to estimate shock pressures experienced by the target rocks. The resulting shock attenuation plan across the archipelago is irregular, probably because the shock wave did not expand from a point or spherical source, and because of the destruction of an originally more regular shock attenuation plan during the central uplift and crater modification stages of the impact process. No impact melt rock bodies have been positively identified on the islands. An impact melt may be present in the annular trough around the islands, though and-based on a weighted mixture of target rocks-may have an intermediate-mafic composition. No such impact melt was found on the archipelago. An Ar-40-Ar-39 release spectrum of a pseudotachylite provides an age of about 436 Ma for the impact structure, substantiating age constraints based on various stratigraphic considerations.

Thermal profiles, crystallization behaviors and microstructure of diacylglycerol-enriched palm oil blends with diacylglycerol-enriched palm olein.

PubMed

Xu, Yayuan; Zhao, Xiaoqing; Wang, Qiang; Peng, Zhen; Dong, Cao

2016-07-01

To elucidate the possible interaction mechanisms between DAG-enriched oils, this study investigated how mixtures of DAG-enriched palm-based oils influenced the phase behavior, thermal properties, crystallization behaviors and the microstructure in binary fat blends. DAG-enriched palm oil (PO-DAGE) was blended with DAG-enriched palm olein (POL-DAGE) in various percentages (0%, 10%, 30%, 50%, 70%, 90%, 100%). Based on the observation of iso-solid diagram and phase diagram, the binary mixture of PO-DAGE/POL-DAGE showed a better compatibility in comparison with their corresponding original blends. DSC thermal profiles exhibited that the melting and crystallization properties of PO-DAGE/POL-DAGE were distinctively different from corresponding original blends. Crystallization kinetics revealed that PO-DAGE/POL-DAGE blends displayed a rather high crystallization rate and exhibited no spherulitic crystal growth. From the results of polarized light micrographs, PO-DAGE/POL-DAGE blends showed more dense structure with very small needle-like crystals than PO/POL. X-ray diffraction evaluation revealed when POL-DAGE was added in high contents to PO-DAGE, above 30%, β-polymorph dominated, and the mount of β' forms crystals was decreasing. Copyright © 2016 Elsevier Ltd. All rights reserved.

A New Model for Simulating Gas Metal Arc Welding based on Phase Field Model

NASA Astrophysics Data System (ADS)

Jiang, Yongyue; Li, Li; Zhao, Zhijiang

2017-11-01

Lots of physical process, such as metal melting, multiphase fluids flow, heat and mass transfer and thermocapillary effect (Marangoni) and so on, will occur in gas metal arc welding (GMAW) which should be considered as a mixture system. In this paper, based on the previous work, we propose a new model to simulate GMAW including Navier-Stokes equation, the phase field model and energy equation. Unlike most previous work, we take the thermocapillary effect into the phase field model considering mixture energy which is different of volume of fluid method (VOF) widely used in GMAW before. We also consider gravity, electromagnetic force, surface tension, buoyancy effect and arc pressure in momentum equation. The spray transfer especially the projected transfer in GMAW is computed as numerical examples with a continuous finite element method and a modified midpoint scheme. Pulse current is set as welding current as the numerical example to show the numerical simulation of metal transfer which fits the theory of GMAW well. From the result compared with the data of high-speed photography and VOF model, the accuracy and stability of the model and scheme are easily validated and also the new model has the higher precieion.

Improved methods for achieving the equilibrium number of phases in mixtures suitable for use in battery electrodes e. g. , for lithiating FeS/sub 2/

DOEpatents

Guidotti, R.A.

1986-06-10

A method is disclosed for preparing lithiated, particulate FeS/sub 2/ useful as a catholyte material in a lithium thermal battery, whereby the latter's voltage regulation properties are improved. The method comprises admixing FeS/sub 2/ and an amount of a lithium-containing compound, whereby the resultant total composition falls in an invariant region of the metallurgical phase diagram of its constituent components. Said lithium-containing compound and FeS/sub 2/ are admixed together with a solid electrolyte compatible with said catholyte, and the mixture is heated at a temperature above the melting point of said electrolyte and at which said mixture reaches its thermodynamic equilibrium number of phases.

Coarse-grained modelling of triglyceride crystallisation: a molecular insight into tripalmitin tristearin binary mixtures by molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Pizzirusso, Antonio; Brasiello, Antonio; De Nicola, Antonio; Marangoni, Alejandro G.; Milano, Giuseppe

2015-12-01

The first simulation study of the crystallisation of a binary mixture of triglycerides using molecular dynamics simulations is reported. Coarse-grained models of tristearin (SSS) and tripalmitin (PPP) molecules have been considered. The models have been preliminarily tested in the crystallisation of pure SSS and PPP systems. Two different quenching procedures have been tested and their performances have been analysed. The structures obtained from the crystallisation procedures show a high orientation order and a high content of molecules in the tuning fork conformation, comparable with the crystalline α phase. The behaviour of melting temperatures for the α phase of the mixture SSS/PPP obtained from the simulations is in qualitative agreement with the behaviour that was experimentally determined.

Phase fields of nickel silicides obtained by mechanical alloying in the nanocrystalline state

NASA Astrophysics Data System (ADS)

Datta, M. K.; Pabi, S. K.; Murty, B. S.

2000-06-01

Solid state reactions induced by mechanical alloying (MA) of elemental blends of Ni and Si have been studied over the entire composition range of the Ni-Si system. A monotonous increase of the lattice parameter of the Ni rich solid solution, Ni(Si), is observed with refinement of crystallite size. Nanocrystalline phase/phase mixtures of Ni(Si), Ni(Si)+Ni31Si12, Ni31Si12+Ni2Si, Ni2Si+NiSi and NiSi+Si, have been obtained during MA, over the composition ranges of 0-10, 10-28, 28-33, 33-50, and >50 at. % Si, respectively. The results clearly suggest that only congruent melting phases, Ni31Si12, Ni2Si, and NiSi form, while the formation of noncongruent melting phases, Ni3Si, Ni3Si2, and NiSi2, is bypassed in the nanocrystalline state. The phase formation during MA has been discussed based on thermodynamic arguments. The predicted phase fields obtained from effective free energy calculations are quite consistent with those obtained during MA.

Deep Eutectic Salt Formulations Suitable as Advanced Heat Transfer Fluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raade, Justin; Roark, Thomas; Vaughn, John

2013-07-22

Concentrating solar power (CSP) facilities are comprised of many miles of fluid-filled pipes arranged in large grids with reflective mirrors used to capture radiation from the sun. Solar radiation heats the fluid which is used to produce steam necessary to power large electricity generation turbines. Currently, organic, oil-based fluid in the pipes has a maximum temperature threshold of 400 °C, allowing for the production of electricity at approximately 15 cents per kilowatt hour. The DOE hopes to foster the development of an advanced heat transfer fluid that can operate within higher temperature ranges. The new heat transfer fluid, when usedmore » with other advanced technologies, could significantly decrease solar electricity cost. Lower costs would make solar thermal electricity competitive with gas and coal and would offer a clean, renewable source of energy. Molten salts exhibit many desirable heat transfer qualities within the range of the project objectives. Halotechnics developed advanced heat transfer fluids (HTFs) for application in solar thermal power generation. This project focused on complex mixtures of inorganic salts that exhibited a high thermal stability, a low melting point, and other favorable characteristics. A high-throughput combinatorial research and development program was conducted in order to achieve the project objective. Over 19,000 candidate formulations were screened. The workflow developed to screen various chemical systems to discover salt formulations led to mixtures suitable for use as HTFs in both parabolic trough and heliostat CSP plants. Furthermore, salt mixtures which will not interfere with fertilizer based nitrates were discovered. In addition for use in CSP, the discovered salt mixtures can be applied to electricity storage, heat treatment of alloys and other industrial processes.« less

Corrosion of metals and alloys in sulfate melts at 750 C

NASA Technical Reports Server (NTRS)

Misra, A. K.

1986-01-01

The corrosion of Ni, Co, Ni-10Cr, Co-21Cr, and IN738 was studied at 750 C in the presence of molten sulfate mixtures (Na2SO4-Li2SO4 and Na2SO4-CoSO4) and in an atmosphere consisting of O2 + 0.12 percent SO2-SO3. The corrosion was observed to be similar for both Na2SO4-Li2SO4 and Na2SO4-CoSO4 melts. The corrosion of Ni and Co took place by the formation of a mixed oxide plus sulfide scale, very similar to the corrosion in SO2 or SO3 alone. The initial stage for the corrosion of Ni-10Cr involved the formation of a thick NiO + Ni3S2 duplex scale, and Cr sulfide was formed during the later stages. A pitting type of morphology was observed for both Co-21Cr and IN738. The pit was Cr sulfide at the beginning, and subsequently the sulfides oxidized to Cr2O3. A base-metal oxide layer was present above the pit, and this was observed to be formed very early in the corrosion process. A mechanism is proposed to explain this. In general, the formation of sulfides appears to be the primary mode of degradation in mixed sulfide melts.

X-ray fluorescence analysis of K, Al and trace elements in chloroaluminate melts

NASA Astrophysics Data System (ADS)

Shibitko, A. O.; Abramov, A. V.; Denisov, E. I.; Lisienko, D. G.; Rebrin, O. I.; Bunkov, G. M.; Rychkov, V. N.

2017-09-01

Energy dispersive x-ray fluorescence spectrometry was applied to quantitative determination of K, Al, Cr, Fe and Ni in chloroaluminate melts. To implement the external standard calibration method, an unconventional way of samples preparation was suggested. A mixture of metal chlorides was melted in a quartz cell at 350-450 °C under a slightly excessive pressure of purified argon (99.999 %). The composition of the calibration samples (CSs) prepared was controlled by means of the inductively coupled plasma atomic emission spectrometry (ICP-AES). The optimal conditions for analytical lines excitation were determined, the analytes calibration curves were obtained. There was some influence of matrix effects in synthesized samples on the analytical signal of some elements. The CSs are to be stored in inert gas atmosphere. The precision, accuracy, and reproducibility factors of the quantitative chemical analysis were computed.

Product differentiation during continuous-flow thermal gradient PCR.

PubMed

Crews, Niel; Wittwer, Carl; Palais, Robert; Gale, Bruce

2008-06-01

A continuous-flow PCR microfluidic device was developed in which the target DNA product can be detected and identified during its amplification. This in situ characterization potentially eliminates the requirement for further post-PCR analysis. Multiple small targets have been amplified from human genomic DNA, having sizes of 108, 122, and 134 bp. With a DNA dye in the PCR mixture, the amplification and unique melting behavior of each sample is observed from a single fluorescent image. The melting behavior of the amplifying DNA, which depends on its molecular composition, occurs spatially in the thermal gradient PCR device, and can be observed with an optical resolution of 0.1 degrees C pixel(-1). Since many PCR cycles are within the field of view of the CCD camera, melting analysis can be performed at any cycle that contains a significant quantity of amplicon, thereby eliminating the cycle-selection challenges typically associated with continuous-flow PCR microfluidics.

Vapor-Saturated Melting of Fertile Peridotite Revisited: A new Experimental Approach and Re-evaluation of the Hydrous Peridotite Solidus

NASA Astrophysics Data System (ADS)

Grove, T. L.

2001-12-01

The vapor-saturated melting relations of peridotite have been determined for a fertile mantle composition of Hart and Zindler (1986, Chem Geol 57: 247) over the pressure range of 1.2 to 2.4 GPa. For example, at 1.2 GPa melt is present at a temperature of 980° C and at 2.4 GPa melt is present at 920° C. These temperatures should be viewed as maximum values for the vapor-saturated solidus (although see below) because the initial melting temperature of multi-phase, multicomponent systems can often be difficult to detect. At 2.4 GPa the melt composition is highly silica-undersaturated and very aluminous ( ~ 21 wt. % Al2O3). Wet mantle melts are thought to be high in silica, but this is not the case for these hydrous melts. At 1.2 GPa, melt fractions are too small to allow reliable analysis. The experiments have been carried out in a piston cylinder apparatus using Au capsules. The starting material is an oxide mixture containing 14.5 wt. % H2O added as brucite. Free water present in the experiment after quenching indicates subsolidus conditions. The absence of fluid in experiments above the vapor-saturated solidus shows that all of the free H2O is dissolved in the melt. The high H2O content of the starting material moves the bulk composition close to the vapor-saturated melt composition, therefore increasing the amount of melt produced close to the solidus and making detection of low melt fraction possible. Studies of the hydrous peridotite solidus carried out between 1970 and 1975 by Mysen and Boettcher, Kushiro and others, Green and Millhollen and others at 2.0 GPa ranged from < 800 to ~ 1000° C, a variation of over 200 degrees. In a subduction zone environment a fluid-rich component released from the slab ascends into hotter overlying mantle and melting initiates at the vapor-saturated solidus. Melting would begin at a depth of ~ 75 km in the mantle wedge, for a realistic thermal structure. Melting would continue as these initial H2O-rich buoyant melts ascend into hotter, shallower mantle and re-equilibrate with their surroundings. The initiation of melting deep in the mantle wedge has implications for both chemical and mechanical processes in the subduction zone environment.

Formation of nano/micro-dispersions with improved dissolution properties upon dispersion of ritonavir melt extrudate in aqueous media.

PubMed

Tho, Ingunn; Liepold, Bernd; Rosenberg, Joerg; Maegerlein, Markus; Brandl, Martin; Fricker, Gert

2010-04-16

The objective of the study was to characterise the aqueous dispersions of ritonavir melt extrudates. More specifically to look into the particular system formed when melt extrudate of a poorly soluble drug dissolved in a hydrophilic polymer matrix containing a surfactant is dispersed in an aqueous medium. Melt extrudates with and without ritonavir were studied. The drug containing extrudate was confirmed to be molecular dispersions of drug in a polymer/surfactant matrix. Particulate dispersions were formed in water from both drug and placebo extrudates. The dispersions were investigated with respect to mean particle size and particle size distribution (photon correlation spectroscopy and optical particle counting), surface charge (zeta potential), particle composition (ultracentrifugation), tendency to form aggregates and precipitate (turbidity), in vitro dissolution rate and drug release. It was concluded that dispersion of melt extrudates in aqueous medium give rise to nano/micro-dispersions. The stability of the nano/micro-dispersion is sensitive to anions and may be subjected to association/aggregation/flocculation as time proceeds after preparation of dispersion. Melt extrudate showed improved dissolution rate and drug release properties compared to crystalline raw material. From studies of single components and physical mixtures of the formulation composition it can be concluded that the drug delivery system itself, namely solid dispersion prepared by melt extrusion technology, plays a key role for the formation of the observed particles. 2010 Elsevier B.V. All rights reserved.

Investigation of nitrate salts for solar latent heat storage

NASA Astrophysics Data System (ADS)

Kamimoto, M.; Tanaka, T.; Tani, T.; Horigome, T.

1980-01-01

The properties of heat transfer in the discharging of a model solar latent heat storage unit based on various nitrate salts and salt mixtures are investigated. A shell-and-tube-type passive heat exchanger containing NaNO3 or eutectic or off-eutectic mixtures of NaNO3 with KNO3 and Ca(NO3)2 was heated to 40 K above the melting temperature of the salt, when air was made to flow through a heat transfer tube at a constant flow rate, and heat transfer material and air temperatures were monitored. Thermal conductivity and the apparent heat transfer coefficient are estimated from the heat extraction rate and temperature profiles, and it is found that although the thermal conductivities of the materials are similar, the off-eutectic salts exhibit higher heat transfer coefficients. Temperature distributions in the NaNO3-KNO3 mixtures are found to be in fairly good agreement with those predicted by numerical solutions of a one-dimensional finite difference equation, and with approximate analytical solutions. It is observed that the temperature of the heat transfer surface drops rapidly after the appearance of a solid phase, due to the low thermal conductivity of the salts, and means of avoiding this temperature drop are considered.

Suppression of turbulent energy cascade due to phase separation in homogenous binary mixture fluid

NASA Astrophysics Data System (ADS)

Takagi, Youhei; Okamoto, Sachiya

2015-11-01

When a multi-component fluid mixture becomes themophysically unstable state by quenching from well-melting condition, phase separation due to spinodal decomposition occurs, and a self-organized structure is formed. During phase separation, free energy is consumed for the structure formation. In our previous report, the phase separation in homogenous turbulence was numerically simulated and the coarsening process of phase separation was discussed. In this study, we extended our numerical model to a high Schmidt number fluid corresponding to actual polymer solution. The governing equations were continuity, Navier-Stokes, and Chan-Hiliard equations as same as our previous report. The flow filed was an isotropic homogenous turbulence, and the dimensionless parameters in the Chan-Hilliard equation were estimated based on the thermophysical condition of binary mixture. From the numerical results, it was found that turbulent energy cascade was drastically suppressed in the inertial subrange by phase separation for the high Schmidt number flow. By using the identification of turbulent and phase separation structure, we discussed the relation between total energy balance and the structures formation processes. This study is financially supported by the Grand-in-Aid for Young Scientists (B) (No. T26820045) from the Ministry of Education, Cul-ture, Sports, Science and Technology of Japan.

Novel polypropylene/inorganic fullerene-like WS2 nanocomposites containing a β-nucleating agent: isothermal crystallization and melting behavior.

PubMed

Naffakh, Mohammed; Marco, Carlos; Ellis, Gary

2012-02-16

The isothermal crystallization and subsequent melting behavior of isotactic polypropylene (iPP) nucleated with different nucleating agents (NAs) are investigated. Tungsten disulfide (IF-WS(2)) and N,N'-dicyclohexyl-2,6-naphthalene (NJ) and dual-additive mixtures are introduced into an iPP matrix to generate new materials that exhibit variable α- and β-polymorphism. As shown in previous work, small amounts of IF-WS(2) or NJ have a nucleating effect during the crystallization of iPP. However, the isothermal crystallization and melting behavior of iPP nucleated by dual α(IF-WS(2))/β(NJ) additive systems are dependent on both the NA composition balance and the crystallization temperature. In particular, our results demonstrate that it is possible to obtain any α-phase to β-phase content ratio by controlling the composition of NAs under appropriate isothermal crystallization conditions. The nucleating behavior of the additives can be illustrated by competitive nucleation, and the correlation between crystallization and melting temperatures and relative α- and β-crystals content in iPP in the nanocomposites is discussed.

Density-Pressure Profiles of Fe-Bearing MgSiO3 Liquid: Effects of Valence and Spin States, and Implications for the Chemical Evolution of the Lower Mantle

NASA Astrophysics Data System (ADS)

Karki, Bijaya B.; Ghosh, Dipta B.; Maharjan, Charitra; Karato, Shun-ichiro; Park, Jeffrey

2018-05-01

Density is a key property controlling the chemical state of Earth's interior. Our knowledge about the density of relevant melt compositions is currently poor at deep-mantle conditions. Here we report results from first-principles molecular-dynamics simulations of Fe-bearing MgSiO3 liquids considering different valence and spin states of iron over the whole mantle pressure conditions. Our simulations predict the high-spin to low-spin transition in both ferrous and ferric iron in the silicate liquid to occur gradually at pressures around 100 GPa. The calculated iron-induced changes in the melt density (about 8% increase for 25% iron content) are primarily due to the difference in atomic mass between Mg and Fe, with smaller contributions (<2%) from the valence and spin states. A comparison of the predicted density of mixtures of (Mg,Fe)(Si,Fe)O3 and (Mg,Fe)O liquids with the mantle density indicates that the density contrast between the melt and residual-solid depends strongly on pressure (depth): in the shallow lower mantle (depths < 1,000 km), the melt is lighter than the solids, whereas in the deep lower mantle (e.g., the D″ layer), the melt density exceeds the mantle density when iron content is relatively high and/or melt is enriched with Fe-rich ferropericlase.

Complex formation and vectorization of a phosphorothioate oligonucleotide with an amphipathic leucine- and lysine-rich peptide: study at molecular and cellular levels.

PubMed

Boukhalfa-Heniche, Fatima-Zohra; Hernández, Belén; Gaillard, Stéphane; Coïc, Yves-Marie; Huynh-Dinh, Tam; Lecouvey, Marc; Seksek, Olivier; Ghomi, Mahmoud

2004-04-15

Optical spectroscopic techniques such as CD, Raman scattering, and fluorescence imaging allowed us to analyze the complex formation and vectorization of a single-stranded 20-mer phosphorothioate oligodeoxynucleotide with a 15-mer amphipathic peptide at molecular and cellular levels. Different solvent mixtures (methanol and water) and molecular ratios of peptide/oligodeoxynucleotide complexes were tested in order to overcome the problems related to solubility. Optimal conditions for both spectroscopic and cellular experiments were obtained with the molecular ratio peptide/oligodeoxynucleotide equal to 21:4, corresponding to a 7:5 ratio for their respective +/- charge ratio. At the molecular level, CD and Raman spectra were consistent with a alpha-helix conformation of the peptide in water or in a methanol-water mixture. The presence of methanol increased considerably the solubility of the peptide without altering its alpha-helix conformation, as evidenced by CD and Raman spectroscopies. UV absorption melting profile of the oligodeoxynucleotide gave rise to a flat melting profile, corresponding to its random structure in solution. Raman spectra of oligodeoxynucleotide/peptide complexes could only be studied in methanol/water mixture solutions. Drastic changes observed in Raman spectra have undoubtedly shown: (a) the perturbation occurred in the peptide secondary structure, and (b) possible interaction between the lysine residues of the peptide and the oligodeoxynucleotide. At the cellular level, the complex was prepared in a mixture of 10% methanol and 90% cell medium. Cellular uptake in optimal conditions for the oligodeoxynucleotide delivery with low cytotoxicity was controlled by fluorescence imaging allowing to specifically locate the compacted oligonucleotide labeled with fluorescein at its 5'-terminus with the peptide into human glioma cells after 1 h of incubation at 37 degrees C. Copyright 2004 Wiley Periodicals, Inc.

Production of anhydrous aluminum chloride composition

DOEpatents

Vandergrift, G.F. III; Krumpelt, M.; Horwitz, E.P.

1981-10-08

A process is described for producing an anhydrous aluminum chloride composition from a water-based aluminous material such as a slurry of aluminum hydroxide in a multistage extraction process in which the aluminum ion is first extracted into an organic liquid containing an acidic extractant and then extracted from the organic phase into an alkali metal chloride or chlorides to form a melt containing a mixture of chlorides of alkali metal and aluminum. In the process, the organic liquid may be recycled. In addition, the process advantageously includes an electrolysis cell for producing metallic aluminum and the alkali metal chloride or chlorides may be recycled for extraction of the aluminum from the organic phase.

Raman study of local ordering processes of solid n-alkanes

NASA Astrophysics Data System (ADS)

Hacura, A.; Zimnicka, B.; Wrzalik, R.

2016-02-01

The microphase separation of n-alkanes with different chain length was investigated by Raman spectroscopy for binary mixture rapidly quenched from the melt. The process was observed as a function of time. The first several minutes after solidification were crucial for the demixing process. For a few weeks old sample the orientational order parameters and were calculated based on the analysis of polarized spectra recorded in the area of the formed domains. The measured values are significantly greater than zero (from 0.17 to 0.32), which indicates the mutual parallel arrangement of the molecules in the domains composed of n-alkanes of the same chain length.

Production of anhydrous aluminum chloride composition and process for electrolysis thereof

DOEpatents

Vandegrift, George F.; Krumpelt, Michael; Horwitz, E. Philip

1983-01-01

A process for producing an anhydrous aluminum chloride composition from a water-based aluminous material such as a slurry of aluminum hydroxide in a multistage extraction process in which the aluminum ion is first extracted into an organic liquid containing an acidic extractant and then extracted from the organic phase into an alkali metal chloride or chlorides to form a melt containing a mixture of chlorides of alkali metal and aluminum. In the process, the organic liquid may be recycled. In addition, the process advantageously includes an electrolysis cell for producing metallic aluminum and the alkali metal chloride or chlorides may be recycled for extraction of the aluminum from the organic phase.

Confirmation of a meteoritic component in impact-melt rocks of the Chesapeake Bay impact structure, Virginia, USA - Evidence from osmium isotopic and PGE systematics

USGS Publications Warehouse

Lee, S.R.; Horton, J. Wright; Walker, R.J.

2006-01-01

The osmium isotope ratios and platinum-group element (PGE) concentrations of impact-melt rocks in the Chesapeake Bay impact structure were determined. The impact-melt rocks come from the cored part of a lower-crater section of suevitic crystalline-clast breccia in an 823 m scientific test hole over the central uplift at Cape Charles, Virginia. The 187Os/188Os ratios of impact-melt rocks range from 0.151 to 0.518. The rhenium and platinum-group element (PGE) concentrations of these rocks are 30-270?? higher than concentrations in basement gneiss, and together with the osmium isotopes indicate a substantial meteoritic component in some impact-melt rocks. Because the PGE abundances in the impact-melt rocks are dominated by the target materials, interelemental ratios of the impact-melt rocks are highly variable and nonchondritic. The chemical nature of the projectile for the Chesapeake Bay impact structure cannot be constrained at this time. Model mixing calculations between chondritic and crustal components suggest that most impact-melt rocks include a bulk meteoritic component of 0.01-0.1% by mass. Several impact-melt rocks with lowest initial 187Os/188Os ratios and the highest osmium concentrations could have been produced by additions of 0.1%-0.2% of a meteoritic component. In these samples, as much as 70% of the total Os may be of meteoritic origin. At the calculated proportions of a meteoritic component (0.01-0.1% by mass), no mixtures of the investigated target rocks and sediments can reproduce the observed PGE abundances of the impact-melt rocks, suggesting that other PGE enrichment processes operated along with the meteoritic contamination. Possible explanations are 1) participation of unsampled target materials with high PGE abundances in the impact-melt rocks, and 2) variable fractionations of PGE during syn- to post-impact events. ?? The Meteoritical Society, 2006.

The amorphous state: first-principles derivation of the Gordon-Taylor equation for direct prediction of the glass transition temperature of mixtures; estimation of the crossover temperature of fragile glass formers; physical basis of the "Rule of 2/3".

PubMed

Skrdla, Peter J; Floyd, Philip D; Dell'Orco, Philip C

2017-08-09

Predicting the glass transition temperature (T g ) of mixtures has applications that span across industries and scientific disciplines. By plotting experimentally determined T g values as a function of the glass composition, one can usually apply the Gordon-Taylor (G-T) equation to determine the slope, k, which subsequently can be used in T g predictions. Traditionally viewed as a phenomenological/empirical model, this work proposes a physical basis for the G-T equation. The proposed equations allow for the calculation of k directly and, hence, they determine/predict the T g values of mixtures algebraically. Two derivations for k are provided, one for strong glass-formers and the other for fragile mixtures, with the modeled trehalose-water and naproxen-indomethacin systems serving as examples of each. Separately, a new equation is described for the first time that allows for the direct determination of the crossover temperature, T x , for fragile glass-formers. Lastly, the so-called "Rule of 2/3", which is commonly used to estimate the T g of a pure amorphous phase based solely on the fusion/melting temperature, T f , of the corresponding crystalline phase, is shown to be underpinned by the heat capacity ratio of the two phases referenced to a common temperature, as evidenced by the calculations put forth for indomethacin and felodipine.

Influence Of The Redox State On The Electrical Conductivity Of Basaltic Melts

NASA Astrophysics Data System (ADS)

Pommier, A.; Gaillard, F.; Pichavant, M.

2007-12-01

The electrical conductivity is an efficient probe of mass transfer processes within silicate melts and magmas. Previous studies have established that the electrical conductivity is sensitive to parameters such as temperature, melt composition and pressure. In contrast to what is known for Fe-bearing minerals, little attention has been given to the influence of redox state on the electrical conductivity of melts. Experiments were performed on tephritic and basaltic compositions respectively from Mt. Vesuvius and Pu'u 'O'o. Measurements were carried out on cylindrical glass samples (OD: 6 mm, ID: 1 mm, L: 8 mm) drilled from glass obtained by fusing each rock sample at 1400°C in air. A two-electrode configuration was adopted, with the electrical impedance being radially measured. A Pt wire was used as the internal electrode whereas a Pt tube served as the external electrode. Experiments were conducted at 1 atm in a vertical furnace between 1200°C and 1300°C, both in air and in a CO-CO2 atmosphere at a fO2 corresponding to NNO+1. Both reduction and oxidation experiments were performed. In reduction experiments (pure CO2 then CO-CO2 gas mixture), electrical conductivities progressively increase with time. The reverse is observed in oxidation experiments (CO-CO2 gas mixture then pure CO2). These variations of electrical conductivities are correlated with modifications of the Fe2+/Fe3+ ratio in the melt, and are consistent with the respective structural roles of Fe2+ and Fe3+. In both types of experiments, a minimum of about 400 mn is necessary before a plateau is reached, interpreted to reflect the kinetics of attainment of the equilibrium Fe2+/Fe3+ ratio in the melt. Differences between plateau and initial values are typically of a few ohms, much higher than the sensitivity of our measurements (better than 0.1 ohm). When increasing temperature, the time required for reaching plateau values decreases. At NNO+1, the electrical activation energy (Ea) was determined for both compositions: Ea=137 kJ/mol (tephrite) and 73 kJ/mol (basalt). Further experiments are necessary to quantify the influence of redox state on electrical conductivity, especially at fO2 below NNO+1.

Method of improving fatigue life of cast nickel based superalloys and composition

DOEpatents

Denzine, Allen F.; Kolakowski, Thomas A.; Wallace, John F.

1978-03-14

The invention consists of a method of producing a fine equiaxed grain structure (ASTM 2-4) in cast nickel-base superalloys which increases low cycle fatigue lives without detrimental effects on stress rupture properties to temperatures as high as 1800.degree. F. These superalloys are variations of the basic nickel-chromium matrix, hardened by gamma prime [Ni.sub.3 (Al, Ti)] but with optional additions of cobalt, tungsten, molybdenum, vanadium, columbium, tantalum, boron, zirconium, carbon and hafnium. The invention grain refines these alloys to ASTM 2 to 4 increasing low cycle fatigue life by a factor of 2 to 5 (i.e. life of 700 hours would be increased to 1400 to 3500 hours for a given stress) as a result of the addition of 0.01% to 0.2% of a member of the group consisting of boron, zirconium and mixtures thereof to aid heterogeneous nucleation. The alloy is vacuum melted and heated to 250.degree.-400.degree. F. above the melting temperature, cooled to partial solidification, thus resulting in said heterogeneous nucleation and fine grains, then reheated and cast at about 50.degree.-100.degree. F. of superheat. Additions of 0.1% boron and 0.1% zirconium (optional) are the preferred nucleating agents.

Investigation on drug solubility enhancement using deep eutectic solvents and their derivatives.

PubMed

Li, Zheng; Lee, Ping I

2016-05-30

Deep eutectic solvent (DES) is a room temperature liquid typically formed by mixing two solid compounds, such as a quaternary ammonium salt (QAS) (e.g. choline chloride) and a hydrogen bond donor (HBD) (e.g. urea or a carboxylic acid) at their eutectic composition. Very often, a range of room temperature liquids can also be obtained near the eutectic composition. Hence, it is more convenient to introduce a more general term deep eutectic solvent derivatives (DESDs) to describe a wide range of DES-like derivatives including those derived from ternary mixtures. The melting point of the mixture is lowered because the hydrogen bonding between DESD components reduces the lattice energy of components of the eutectic system. Based on the analysis of available data for 22 such choline chloride-based DES pairs, we found that the observed melting point depression can be statistically correlated with the difference between the hydrogen bonding contribution (δh) and the polar contribution (δp) to the solubility parameter of the hydrogen bond donor (HBD) component. The correlation was validated with a new DESD based on glycolic acid and choline chloride, which form DESDs at a molar ratio between 1:1 and 1:4 with DES-like properties. As a room temperature liquid, this DESD exhibits a wide range of solubility enhancement on several weakly basic poorly water-soluble drugs. For example, the solubility of itraconazole, piroxicam, lidocaine, and posaconazole has been observed to increase by 6700, 430, 28, and 6400-fold, respectively as compared to their aqueous solubility at room temperature. Furthermore, another new ternary DESD based on choline chloride, glycolic acid, and oxalic acid at a molar ratio of 1:1.6:0.4 is shown to further increase the solubility of itraconazole to a remarkable level of 5.36mg/mL (a 53,600-fold increase!). Because the components of such DESDs can include those biodegradable ones that had previously been used in formulated human products, the potential applicability of suitable DESDs to drug delivery, especially in enhancing drug solubility for topical formulations could be very attractive. Copyright © 2016 Elsevier B.V. All rights reserved.

Shock Reactivity of Non-Porous Mixtures of Manganese and Sulfur

NASA Astrophysics Data System (ADS)

Jette, Francois-Xavier; Goroshin, Samuel; Higgins, Andrew

2007-06-01

Stoichiometric mixtures of manganese powder and sulfur were melt-cast into solid pellets in order to study the mechanism of shock-enhanced reactivity in non-porous heterogeneous mixtures. This mixture was selected due to the large exothermic heat release of the manganese-sulfur reaction (214 kJ/mol), which causes the reaction to be self-sustaining once initiated. The test samples were placed in planar recovery ampoules and a strong shock was delivered via the detonation of a charge of amine-sensitized nitromethane. Various shock strengths were achieved by placing different thicknesses of PMMA attenuator between the explosive charge and the ampoule. The results confirmed that shock-induced reactions can be produced in the absence of porosity. Indeed, the critical shock pressure that caused ignition of the mixture in the ampoule was found to be in the range 2.2 - 3.8 GPa (pressures were estimated using LS-DYNA simulations). In the cases where the shock was too weak to cause ignition in the ampoule, the sample was extracted and its ignition temperature was determined using a differential thermal analyzer.

The Phase Behavior of γ-Oryzanol and β-Sitosterol in Edible Oil.

PubMed

Sawalha, Hassan; Venema, Paul; Bot, Arjen; Flöter, Eckhard; Adel, Ruud den; van der Linden, Erik

The phase behavior of binary mixtures of γ-oryzanol and β-sitosterol and ternary mixtures of γ-oryzanol and β-sitosterol in sunflower oil was studied. Binary mixtures of γ-oryzanol and β-sitosterol show double-eutectic behavior. Complex phase behavior with two intermediate mixed solid phases was derived from differential scanning calorimetry (DSC) and small-angle X-ray scattering (SAXS) data, in which a compound that consists of γ-oryzanol and β-sitosterol molecules at a specific ratio can be formed. SAXS shows that the organization of γ-oryzanol and β-sitosterol in the mixed phases is different from the structure of tubules in ternary systems. Ternary mixtures including sunflower oil do not show a sudden structural transition from the compound to a tubule, but a gradual transition occurs as γ-oryzanol and β-sitosterol are diluted in edible oil. The same behavior is observed when melting binary mixtures of γ-oryzanol and β-sitosterol at higher temperatures. This indicates the feasibility of having an organogelling agent in dynamic exchange between solid and liquid phase, which is an essential feature of triglyceride networks.

Rheological Study Of The Mixture Of Acetaminophen And Polyethylene Oxide For Hot-Melt Extrusion Application (PREPRINT)

DTIC Science & Technology

2011-01-01

kinetics does not affect the solubility data obtained. As a result, a long testing period is required, which may cause the thermal degradation ...Acetaminophen, with a commercial name of paracetamol , was supplied by Spectrum Quality Products, Inc. (Gardena, CA 90428). It has a formula of C8H9O2

Electrical conductivity of low-temperature NaCl-KCl-ZrCl4 melts

NASA Astrophysics Data System (ADS)

Salyulev, A. B.; Khokhlov, V. A.; Red'kin, A. A.

2014-08-01

The dependences of the electrical conductivity of NaCl-KCl-ZrCl4 molten mixtures with a molar ratio NaCl : KCl = 8 : 29 on the temperature (temperature range of 300-540°C) and the ZrCl4 concentration (54.3-75.2 mol %) have been measured for the first time using unique cells.

Preparation of Bi-Sr-Ca-Cu-O superconductors from oxide-glass precursors

DOEpatents

Hinks, David G.; Capone, II, Donald W.

1992-01-01

A superconductor and precursor therefor from oxide mixtures of Ca, Sr, Bi and Cu. Glass precursors quenched to elevated temperatures result in glass free of crystalline precipitates having enhanced mechanical properties. Superconductors are formed from the glass precursors by heating in the presence of oxygen to a temperature below the melting point of the glass.

Effects of high-melting methyl esters on crystallization properties of fatty acid methyl ester mixtures

USDA-ARS?s Scientific Manuscript database

Biodiesel is a renewable alternative diesel fuel made from vegetable oils and animal fats. The most common form of biodiesel in the United States are fatty acid methyl esters (FAME) from soybean, canola, and used cooking oils, waste greases, and tallow. Cold flow properties of biodiesel depend on th...

Energy-Storage Modules for Active Solar Heating and Cooling

NASA Technical Reports Server (NTRS)

Parker, J. C.

1982-01-01

34 page report describes a melting salt hydrate that stores 12 times as much heat as rocks and other heavy materials. Energy is stored mostly as latent heat; that is, heat that can be stored and recovered without any significant change in temperature. Report also describes development, evaluation and testing of permanently sealed modules containing salt hydrate mixture.

On liquid phases in cometary nuclei

NASA Astrophysics Data System (ADS)

Miles, Richard; Faillace, George A.

2012-06-01

In this paper we review the relevant literature and investigate conditions likely to lead to melting of H2O ice, methanol (CH3OH) ice, ethane (C2H6) ice and other volatile ices in cometary nuclei. On the basis of a heat balance model which takes account of volatiles loss, we predict the formation of occasional aqueous and hydrocarbon liquid phases in subsurface regions at heliocentric distances, rh of 1-3 AU, and 5-12 AU, respectively. Low triple-point temperatures and low vapour pressures of C2H6, C3H8, and some higher-order alkanes and alkenes, favour liquid phase formation in cometary bodies at high rh. Microporosity and the formation of a stabilization crust occluding the escape of volatiles facilitate liquid-phase formation. Characteristics of the near-surface which favour subsurface melting include; low effective surface emissivity (at low rh), high amorphous carbon content, average pore sizes of ˜10 μm or less, presence of solutes (e.g. CH3OH), mixtures of C2-C6 hydrocarbons (for melting at high rh), diurnal thermal cycling, and slow rotation rate. Applying the principles of soil mechanics, capillary forces are shown to initiate pre-melting phenomena and subsequent melting, which is expected to impart considerable strength of ˜104 Pa in partially saturated layers, reducing porosity and permeability, enhancing thermal conductivity and heat transfer. Diurnal thermal cycling is expected to have a marked effect on the composition and distribution of H2O ice in the near-surface leading to frost heave-type phenomena even where little if any true melting occurs. Where melting does take place, capillary suction in the wetted zone has the potential to enhance heat transfer via capillary wetting in a low-gravity environment, and to modify surface topography creating relatively smooth flat-bottomed features, which have a tendency to be located within small depressions. An important aspect of the "wetted layer" model is the prediction that diurnal melt-freeze cycles alter the mixing ratio vs. depth of solutes present, or of other miscible components, largely through a process of fractional crystallization, but also potentially involving frost heave. Wetted layers are potentially durable and can involve significant mass transport of volatile materials in the near-surface, increasing in extent over many rotations of the nucleus prior to and just after perihelion passage, and causing stratification and trapping of the lowest-melting mixtures at depths of several metres. A possible mechanism for cometary outbursts is proposed involving a heat pulse reaching the liquid phase in the deepest wetted zone, leading to supersaturation and triggering the sudden release under pressure of dissolved gases, in particular CO2, CO, CH4 or N2, contained beneath a consolidated near-surface layer. This study indicates that liquid water can persist for long periods of time in the near-surface of some intermediate-sized bodies (102-103 km radius) within protoplanetary discs.

Carbon Solubility in Metallic Iron and Melting Relations in the Fe-C System at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

Wang, Y.; Fei, Y.

2006-05-01

Carbon has been proposed to be one of the light elements in the Earth's core. Knowledge of phase relations in the Fe-C system at high pressure and temperature is needed to understand the carbon content in the core and its effect on the physical properties and the temperature of the core. Experimental data in this system at high pressure and temperature are limited. In this study we report new experimental data on melting relations up to 25 GPa. The experiments were performed using piston-cylinder and multi-anvil devices at the Geophysical Laboratory. Mixtures of fine power of pure iron and graphite with different carbon content were prepared as starting materials. The starting materials were loaded into MgO capsules and then compressed to the desired pressures, using various high-pressure cell assemblies that have been calibrated at high pressure. High temperatures were achieved using either graphite heater (<6 GPa) or rhenium heater at higher pressures and measured with a tungsten-rhenium thermocouple. Melting relations were determined with a JEOL JXA-8900 electron microprobe, based on quench textures and chemical composition of the quenched phases. Powder X- ray diffraction technique was also used to identify phases and determine unit cell parameters. A positive slope between the solubility of carbon in metallic iron and pressure was found at elevated temperatures. The eutectic temperature increases with increasing pressure. The liquidus temperature determined in this study is significantly lower than the calculated value in previous study. Our study presents directly experimental measurements of the melting relations in the Fe-C system at high pressure and temperature, which provides better constraints on composition and temperature of the Earth's core.

A Novel Method of Preparation of Inorganic Glasses by Microwave Irradiation

NASA Astrophysics Data System (ADS)

Vaidhyanathan, B.; Ganguli, Munia; Rao, K. J.

1994-12-01

Microwave heating is shown to provide an extremely facile and automatically temperature-controlled route to the synthesis of glasses. Glass-forming compositions of several traditional and novel glasses were melted in a kitchen microwave oven, typically within 5 min and quenched into glasses. This is only a fraction of the time required in normal glass preparation methods. The rapidity of melting minimizes undesirable features such as loss of components of the glass, variation of oxidation states of metal ions, and oxygen loss leading to reduced products in the glass such as metal particles. This novel procedure of preparation is applicable when at least one of the components of the glass-forming mixture absorbs microwaves.

Field-theoretical approach to a dense polymer with an ideal binary mixture of clustering centers.

PubMed

Fantoni, Riccardo; Müller-Nedebock, Kristian K

2011-07-01

We propose a field-theoretical approach to a polymer system immersed in an ideal mixture of clustering centers. The system contains several species of these clustering centers with different functionality, each of which connects a fixed number segments of the chain to each other. The field theory is solved using the saddle point approximation and evaluated for dense polymer melts using the random phase approximation. We find a short-ranged effective intersegment interaction with strength dependent on the average segment density and discuss the structure factor within this approximation. We also determine the fractions of linkers of the different functionalities.

Detonation performance measurements of cyclotol 80/20

NASA Astrophysics Data System (ADS)

Kuiper, T. A.; Anderson, E. K.; Short, M.; Jackson, S. I.

2017-01-01

Cyclotol is a melt-castable high explosive composed of RDX and TNT, and typically a small amount of HMX. The term Cyclotol may apply to other mixtures of these components, but for the present work, experiments were conducted using Cyclotol containing 80 wt% RDX and HMX and 20 wt% TNT (we will refer to mixtures of RDX and TNT using the notation RDX%/TNT%). In the current effort, we report detonation velocity measurements at several diameters for unconfined rate sticks. The results are compared to prior diameter-effect data for Cyclotol 77/23, and a density-corrected Eyring-form fit for all available rate-stick data is reported.

Alkali-lead-iron phosphate glass and associated method

DOEpatents

Boatner, Lynn A.; Sales, Brian C.; Franco, Sofia C. S.

1994-01-01

A glass composition and method of preparation utilizes a mixture consisting of phosphorus oxide within the range of about 40 to 49 molar percent, lead oxide within the range of about 10 to 25 molar percent, iron oxide within the range of about 10 to 17 molar percent and an alkali oxide within the range of about 23 to 30 molar percent. The glass resulting from the melting and subsequent solidifying of the mixture possesses a high degree of durability and a coefficient of thermal expansion as high as that of any of a number of metals. Such features render this glass highly desirable in glass-to-metal seal applications.

Insight into the Li{sub 2}CO{sub 3}–K{sub 2}CO{sub 3} eutectic mixture from classical molecular dynamics: Thermodynamics, structure, and dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corradini, Dario; Vuilleumier, Rodolphe, E-mail: rodolphe.vuilleumier@ens.fr; Sorbonne Universités, UPMC Univ. Paris 06, PASTEUR, 75005 Paris

We use molecular dynamics simulations to study the thermodynamics, structure, and dynamics of the Li{sub 2}CO{sub 3}–K{sub 2}CO{sub 3} (62:38 mol. %) eutectic mixture. We present a new classical non-polarizable force field for this molten salt mixture, optimized using experimental and first principles molecular dynamics simulations data as reference. This simple force field allows efficient molecular simulations of phenomena at long time scales. We use this optimized force field to describe the behavior of the eutectic mixture in the 900–1100 K temperature range, at pressures between 0 and 5 GPa. After studying the equation of state in these thermodynamic conditions, wemore » present molecular insight into the structure and dynamics of the melt. In particular, we present an analysis of the temperature and pressure dependence of the eutectic mixture’s self-diffusion coefficients, viscosity, and ionic conductivity.« less

Structure and stability of charged colloid-nanoparticle mixtures

NASA Astrophysics Data System (ADS)

Weight, Braden M.; Denton, Alan R.

2018-03-01

Physical properties of colloidal materials can be modified by addition of nanoparticles. Within a model of like-charged mixtures of particles governed by effective electrostatic interactions, we explore the influence of charged nanoparticles on the structure and thermodynamic phase stability of charge-stabilized colloidal suspensions. Focusing on salt-free mixtures of particles of high size and charge asymmetry, interacting via repulsive Yukawa effective pair potentials, we perform molecular dynamics simulations and compute radial distribution functions and static structure factors. Analysis of these structural properties indicates that increasing the charge and concentration of nanoparticles progressively weakens correlations between charged colloids. We show that addition of charged nanoparticles to a suspension of like-charged colloids can induce a colloidal crystal to melt and can facilitate aggregation of a fluid suspension due to attractive van der Waals interactions. We attribute the destabilizing influence of charged nanoparticles to enhanced screening of electrostatic interactions, which weakens repulsion between charged colloids. This interpretation is consistent with recent predictions of an effective interaction theory of charged colloid-nanoparticle mixtures.

K-Rich Basaltic Sources beneath Ultraslow Spreading Central Lena Trough in the Arctic Ocean

NASA Astrophysics Data System (ADS)

Ling, X.; Snow, J. E.; Li, Y.

2016-12-01

Magma sources fundamentally influence accretion processes at ultraslow spreading ridges. Potassium enriched Mid-Ocean Ridge Basalt (K-MORB) was dredged from the central Lena Trough (CLT) in the Arctic Ocean (Nauret et al., 2011). Its geochemical signatures indicate a heterogeneous mantle source with probable garnet present under low pressure. To explore the basaltic mantle sources beneath the study area, multiple models are carried out predicting melting sources and melting P-T conditions in this study. P-T conditions are estimated by the experimental derived thermobarometer from Hoang and Flower (1998). Batch melting model and major element model (AlphaMELTs) are used to calculate the heterogeneous mantle sources. The modeling suggests phlogopite is the dominant H2O-K bearing mineral in the magma source. 5% partial melting of phlogopite and amphibole mixing with depleted mantle (DM) melt is consistent with the incompatible element pattern of CLT basalt. P-T estimation shows 1198-1212oC/4-7kbar as the possible melting condition for CLT basalt. Whereas the chemical composition of north Lena Trough (NLT) basalt is similar to N-MORB, and the P-T estimation corresponds to 1300oC normal mantle adiabat. The CLT basalt bulk composition is of mixture of 40% of the K-MORB endmember and an N-MORB-like endmember similar to NLT basalt. Therefore the binary mixing of the two endmembers exists in the CLT region. This kind of mixing infers to the tectonic evolution of the region, which is simultaneous to the Arctic Ocean opening.

Density and Adiabatic Compressibility of the Immiscible Molten AgBr+LiCl Mixture

NASA Astrophysics Data System (ADS)

Stepanov, Victor P.; Kulik, Nina P.

2017-04-01

The adiabatic compressibility, β, of the immiscible liquid mixture 0.52 LiCl+0.48 AgBr (the top of the miscibility gap) was experimentally investigated in the temperature range from the melting point to the critical mixing temperature using the sound velocity values, u, measured by the pulse method, and the density quantities, ρ, which were determined using the hydrostatic weight procedure based on the relationship β=u- 2ρ- 1. It is shown that the coefficients of the temperature dependencies for the compressibility and density of the upper and lower equilibrium phases have opposite signs because of the superposition of the intensity of the thermal motion of the ions and the change in the composition of the phases. The differences, ∆β and ∆ρ, in the magnitudes of the compressibility and density for the equilibrium phases decrease with temperature elevation. The temperature dependencies of the compressibility and density difference are described using the empirical equations ∆β≈(Tc-T)0.438 and ∆ρ≈(Tc-T)0.439.

Statistical Mechanical Theory of Penetrant Diffusion in Polymer Melts and Glasses

NASA Astrophysics Data System (ADS)

Zhang, Rui; Schweizer, Kenneth

We generalize our force-level, self-consistent nonlinear Langevin equation theory of activated diffusion of a dilute spherical penetrant in hard sphere fluids to predict the long-time diffusivity of molecular penetrants in supercooled polymer liquids and non-aging glasses. Chemical complexity is treated using an a priori mapping to a temperature-dependent hard sphere mixture model where polymers are disconnected into effective spheres based on the Kuhn length as the relevant coarse graining scale. A key parameter for mobility is the penetrant to polymer segment diameter ratio, R. Our calculations agree well with experimental measurements for a wide range of temperatures, penetrant sizes (from gas molecules with R ~0.3 to aromatic molecules with R ~1) and diverse amorphous polymers, over 10 decades variation of penetrant diffusivity. Structural parameter transferability is good. We have also formulated a theory at finite penetrant loading for the coupled penetrant-polymer dynamics in chemically (nearly) matched mixtures (e.g., toluene-polystyrene) which captures well the increase of penetrant diffusivity and decrease of polymer matrix vitrification temperature with increasing loading.

Incorporation of Multiwalled Carbon Nanotubes into High Temperature Resin Using Dry Mixing Techniques

NASA Technical Reports Server (NTRS)

Ghose, Sayata; Watson, Kent A.; Delozier, Donavon M.; Working, Dennis C.; Siochi, Emilie J.; Connell, John W.

2006-01-01

As part of an ongoing effort to develop multifunctional advanced composites, blends of PETI330 and multiwalled carbon nanotubes (MWNTs) were prepared and characterized. Dry mixing techniques were employed and the maximum loading level of the MWNT chosen was based primarily on its effect on melt viscosity. The PETI330/ MWNT mixtures were prepared at concentrations ranging from 3 to 25 wt %. The resulting powders were characterized for homogeneity, thermal and rheological properties and extrudability as continuous fibers. Based on the characterization results, samples containing 10, 15 and 20 wt % MWNTs were chosen for more comprehensive evaluation. Samples were also prepared using in situ polymerization and solution mixing techniques and their properties were compared with the ball-mill prepared samples. The preparation and characterization of PETI330/ MWNT nanocomposites are discussed herein.

Peptide nucleic acid probe-based fluorescence melting curve analysis for rapid screening of common JAK2, MPL, and CALR mutations.

PubMed

Park, Joonhong; Song, Minsik; Jang, Woori; Chae, Hyojin; Lee, Gun Dong; Kim, KyungTak; Park, Heekyung; Kim, Myungshin; Kim, Yonggoo

2017-02-01

We developed and evaluated the feasibility of peptide nucleic acid (PNA)-based fluorescence melting curve analysis (FMCA) to detect common mutations in myeloproliferative neoplasms (MPNs). We have set up two separate reactions of PNA-based FMCA: JAK2 V617F &CALR p.Leu367fs*46 (set A) and MPL W515L/K &CALR p.Lys385fs*47 (set B). Clinical usefulness was validated with allele-specific real-time PCR, fragment analysis, Sanger sequencing in 57 BCR-ABL1-negative MPNs. The limit of detection (LOD) of PNA-based FMCA was approximately 10% for each mutation and interference reactions using mixtures of different mutations were not observed. Non-specific amplification was not observed in normal control. PNA-based FMCA was able to detect all JAK2 V617F (n=20), CALR p.Leu367fs*46 (n=10) and p.Lys385fs*47 (n=8). Three of six MPL mutations were detected except three samples with low mutant concentration in out of LOD. JAK2 exon 12 mutations (n=7) were negative without influencing V617F results. Among six variant CALR exon 9 mutations, two were detected by this method owing to invading of probe binding site. PNA-based FMCA for detecting common JAK2, MPL, and CALR mutations is a rapid, simple, and sensitive technique in BCR-ABL1-negative MPNs with >10% mutant allele at the time of initial diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Stability of Carbonated Eclogite in the Upper Mantle: Experimental Solidus from 2 to 9 GPa

NASA Astrophysics Data System (ADS)

Dasgupta, R.; Withers, A. C.; Hirschmann, M. M.

2003-12-01

Carbonates are pervasive alteration products of the oceanic crust and likely survive subduction-related dehydration and/or melting. Thus, significant quantities of carbonated refractory eclogite are probably delivered to the deeper mantle. The melting behavior of such recycled carbonate influences the fate of recycled carbon, determines the possible sources and depths of carbonated metasomatic melts in the mantle, and delimits the conditions under which carbonated eclogite may act as a source of carbonatite and other types of magmatic CO2. We present partial melting experiments of carbonated eclogite that constrain the solidus and near solidus phase relations from 2 to 9 GPa. To simulate the near-isochemical nature of ocean floor carbonation, the starting material was prepared by adding 5 wt.% CO2 in the form of a mixture of Fe-Mg-Ca-Na-K carbonates to a bimineralic eclogite from Salt Lake crater, Oahu, Hawaii. The starting composition is a reasonable approximation of carbonated oceanic crust from which siliceous hydrous fluid has been extracted by subduction. We find that melt-present versus melt-absent conditions can be distinguished based on textural criteria. Garnet and cpx appear in all the experiments. Between 2 and 3 GPa, the subsolidus assemblage also includes calcite-dolomitess + ilmenite, whereas above the solidus (950-975 ° C at 2 GPa and 1050-1075 ° C at 3 GPa) calcio-dolomitic liquid appears. From 3 to 4.5 GPa, dolomitess becomes stable at the solidus and the near solidus melt becomes increasingly dolomitic. Appearance of dolomite above 3 GPa is accompanied by a negative Clapeyron slope of the solidus, with the cusp located between 995 and 1025 ° C at ca. 4 GPa. Above 4-4.5 GPa, the solidus again rises with increasing pressure to ca. 1245 ° C at 9 GPa and magnesite becomes the subsolidus carbonate. Dolomitic melt coexists with magnesite + garnet + cpx + rutile between 5 and 9 GPa. If extrapolated to higher pressures, the carbonated eclogite solidus intersects the oceanic geotherm deeper than 400 km. Thus, eclogite cannot host carbonates in the asthenosphere. Carbonated eclogite bodies entering the convecting upper mantle would release carbonate melt in the mantle transition zone. Upon release, this small volume, highly reactive melt could be an effective agent of deep mantle metasomatism. Comparison of our eclogite-CO2 solidus with that of peridotite-CO2 shows a shallower solidus-geotherm intersection for the latter. This implies that carbonated peridotite is a more likely proximal source of magmatic carbon in oceanic provinces. However, carbonated eclogite is a potential source of continental carbonatites, as its solidus crosses the continental shield geotherm at ca. 4 GPa.

Thermodynamic Investigation of the Interaction between Polymer and Gases

NASA Astrophysics Data System (ADS)

Mahmood, Syed Hassan

This thesis investigates the interaction between blowing agents and polymer matrix. Existing theoretical model was further developed to accommodate the polymer and blowing agent under study. The obtained results are not only useful for the optimization of the plastic foam fabrication process but also provides a different approach to usage of blowing agents. A magnetic suspension balance and an in-house visualizing dilatometer were used to obtain the sorption of blowing agents in polymer melts under elevated temperature and pressure. The proposed theoretical approach based on the thermodynamic model of SS-EOS is applied to understand the interaction of blowing agents with the polymer melt and one another (in the case of blend blowing agent). An in-depth study of the interaction of a blend of CO2 and DME with PS was conducted. Experimental volume swelling of the blend/PS mixture was measured and compared to the theoretical volume swelling obtained via ternary based SS-EOS, insuring the models validity. The effect of plasticization due to dissolution of DME on the solubility of CO2 in PS was then investigated by utilizing the aforementioned model. It was noted that the dissolution of DME increased the concentration of CO2 in PS and lowering the saturation pressure needed to dissolved a certain amount of CO2 in PS melt. The phenomenon of retrograde vitrification in PMMA induced due dissolution of CO2 was investigated in light of the thermodynamic properties resulting from the interaction of polymer and blowing agent. Solubility and volume swelling were measured in the pressure and temperature ranges promoting vitrification phenomenon, with relation being established between the thermodynamic properties and the vitrification process. Foaming of PMMA was conducted at various temperature values to investigate the application of this phenomenon.

Determination of optimum processing temperature for transformation of glyceryl monostearate.

PubMed

Yajima, Toshio; Itai, Shigeru; Takeuchi, Hirofumi; Kawashima, Yoshiaki

2002-11-01

The purpose of this study was to clarify the mechanism of transformation from alpha-form to beta-form via beta'-form of glyceryl monostearate (GM) and to determine the optimum conditions of heat-treatment for physically stabilizing GM in a pharmaceutical formulation. Thermal analysis repeated twice using a differential scanning calorimeter (DSC) were performed on mixtures of two crystal forms. In the first run (enthalpy of melting: DeltaH1), two endothermic peaks of alpha-form and beta-form were observed. However, in the second run (enthalpy of melting: DeltaH2), only the endothermic peak of the alpha-form was observed. From a strong correlation observed between the beta-form content in the mixture of alpha-form and beta-form and the enthalpy change, (DeltaH1-DeltaH2)/DeltaH2, beta-form content was expressed as a function of the enthalpy change. Using this relation, the stable beta-form content during the heat-treatment could be determined, and the maximum beta-form content was obtained when the heat-treatment was carried out at 50 degrees C. An inflection point existed in the time course of transformation of alpha-form to beta-form. It was assumed that almost all of alpha-form transformed to beta'-form at this point, and that subsequently only transformation from beta'-form to beta-form occurred. Based on this aspect, the transformation rate equations were derived as consecutive reaction. Experimental data coincided well with the theoretical curve. In conclusion, GM was transformed in the consecutive reaction, and 50 degrees C was the optimum heat-treatment temperature for transforming GM from the alpha-form to the stable beta-form.

A polymerase chain reaction-coupled high-resolution melting curve analytical approach for the monitoring of monospecificity of avian Eimeria species.

PubMed

Kirkpatrick, Naomi C; Blacker, Hayley P; Woods, Wayne G; Gasser, Robin B; Noormohammadi, Amir H

2009-02-01

Coccidiosis is a significant disease of poultry caused by different species of Eimeria. Differentiation of Eimeria species is important for the quality control of the live attenuated Eimeria vaccines derived from monospecific lines of Eimeria spp. In this study, high-resolution melting (HRM) curve analysis of the amplicons generated from the second internal transcribed spacer of nuclear ribosomal DNA (ITS-2) was used to distinguish between seven pathogenic Eimeria species of chickens, and the results were compared with those obtained from the previously described technique, capillary electrophoresis. Using a series of known monospecific lines of Eimeria species, HRM curve analysis was shown to distinguish between Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox and Eimeria tenella. Computerized analysis of the HRM curves and capillary electrophoresis profiles could detect the dominant species in several specimens containing different ratios of E. necatrix and E. maxima and of E. tenella and E. acervulina. The HRM curve analysis identified all of the mixtures as "variation" to the reference species, and also identified the minor species in some mixtures. Computerized HRM curve analysis also detected impurities in 21 possible different combinations of the seven Eimeria species. The PCR-based HRM curve analysis of the ITS-2 provides a powerful tool for the detection and identification of pure Eimeria species. The HRM curve analysis could also be used as a rapid tool in the quality assurance of Eimeria vaccine production to confirm the purity of the monospecific cell lines. The HRM curve analysis is rapid and reliable and can be performed in a single test tube in less than 3 h.

A New Method of Constructing a Drug-Polymer Temperature-Composition Phase Diagram Using Hot-Melt Extrusion.

PubMed

Tian, Yiwei; Jones, David S; Donnelly, Conor; Brannigan, Timothy; Li, Shu; Andrews, Gavin P

2018-04-02

Current experimental methodologies used to determine the thermodynamic solubility of an API within a polymer typically involves establishing the dissolution/melting end point of the crystalline API within a physical mixture or through the use of the glass transition temperature measurement of a demixed amorphous solid dispersion. The measurable "equilibrium" points for solubility are normally well above the glass transition temperature of the system, meaning extrapolation is required to predict the drug solubility at pharmaceutically relevant temperatures. In this manuscript, we argue that the presence of highly viscous polymers in these systems results in experimental data that exhibits an under or overestimated value relative to the true thermodynamic solubility. In previous work, we demonstrated the effects of experimental conditions and their impact on measured and predicted thermodynamic solubility points. In light of current understanding, we have developed a new method to limit error associated with viscosity effects for application in small-scale hot-melt extrusion (HME). In this study, HME was used to generate an intermediate (multiphase) system containing crystalline drug, amorphous drug/polymer-rich regions as well as drug that was molecularly dispersed in polymer. An extended annealing method was used together with high-speed differential scanning calorimetry to accurately determine the upper and lower boundaries of the thermodynamic solubility of a model drug-polymer system (felodipine and Soluplus). Compared to our previously published data, the current results confirmed our hypothesis that the prediction of the liquid-solid curve using dynamic determination of dissolution/melting end point of the crystalline API physical mixture presents an underestimation relative to the thermodynamic solubility point. With this proposed method, we were able to experimentally measure the upper and lower boundaries of the liquid-solid curve for the model system. The relationship between inverse temperature and drug-polymer solubility parameter (χ) remained linear at lower drug loadings. Significantly higher solubility and miscibility between the felodipine-Soluplus system were derived from the new χ values.

METHOD OF MAKING UO$sub 2$-Bi SLURRIES

DOEpatents

Hahn, H.T.

1960-05-24

A process is given of preparing an easily dispersible slurry of uranium dioxide in bismuth. A mixture of bismuth oxide, uranium, and bismuth are heated in a capsule to a temperature over the melting point of bismuth oxide. The amount of bismuth oxide used is less than that stoichiometrically required because the oxygen in the capsule also enters into the reaction.

Triple shape memory effects of cross-linked polyethylene/polypropylene blends with cocontinuous architecture.

PubMed

Zhao, Jun; Chen, Min; Wang, Xiaoyan; Zhao, Xiaodong; Wang, Zhenwen; Dang, Zhi-Min; Ma, Lan; Hu, Guo-Hua; Chen, Fenghua

2013-06-26

In this paper, the triple shape memory effects (SMEs) observed in chemically cross-linked polyethylene (PE)/polypropylene (PP) blends with cocontinuous architecture are systematically investigated. The cocontinuous window of typical immiscible PE/PP blends is the volume fraction of PE (v(PE)) of ca. 30-70 vol %. This architecture can be stabilized by chemical cross-linking. Different initiators, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane (DHBP), dicumylperoxide (DCP) coupled with divinylbenzene (DVB) (DCP-DVB), and their mixture (DHBP/DCP-DVB), are used for the cross-linking. According to the differential scanning calorimetry (DSC) measurements and gel fraction calculations, DHBP produces the best cross-linking and DCP-DVB the worst, and the mixture, DHBP/DCP-DVB, is in between. The chemical cross-linking causes lower melting temperature (Tm) and smaller melting enthalpy (ΔHm). The prepared triple shape memory polymers (SMPs) by cocontinuous immiscible PE/PP blends with v(PE) of 50 vol % show pronounced triple SMEs in the dynamic mechanical thermal analysis (DMTA) and visual observation. This new strategy of chemically cross-linked immiscible blends with cocontinuous architecture can be used to design and prepare new SMPs with triple SMEs.

Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jantzen, Carol M.

Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO 2 and B 2O 3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter themore » canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. Furthermore, the molecular structure of the glass also controls the glass durability, i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement.« less

Using polymerization, glass structure, and quasicrystalline theory to produce high level radioactive borosilicate glass remotely: a 20+ year legacy

DOE PAGES

Jantzen, Carol M.

2017-03-27

Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO 2 and B 2O 3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter themore » canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. Furthermore, the molecular structure of the glass also controls the glass durability, i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement.« less

Ionic Liquids to Replace Hydrazine

NASA Technical Reports Server (NTRS)

Koelfgen, Syri; Sims, Joe; Forton, Melissa; Allan, Barry; Rogers, Robin; Shamshina, Julia

2011-01-01

A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

Analysis of the heat capacity for pure CH4 and CH4/CCl4 on graphite near the melting point and calculation of the T-X phase diagram for (CH3)CCl3 + CCl4

NASA Astrophysics Data System (ADS)

Yurtseven, Hamit; Yılmaz, Aygül

2016-06-01

We study the temperature dependence of the heat capacity Cp for the pure CH4 and the coadsorbed CH4/CCl4 on graphite near the melting point. The heat capacity peaks are analyzed using the experimental data from the literature by means of the power-law formula. The critical exponents for the heat capacity are deduced below and above the melting point for CH4 (Tm = 104.8 K) and CH4/CCl4 (Tm = 99.2 K). Our exponent values are larger as compared with the predicted values of some theoretical models exhibiting second order transition. Our analyses indicate that the pure methane shows a nearly second order (weak discontinuity in the heat capacity peak), whereas the transition in coadsorbed CH4/CCl4 is of first order (apparent discontinuity in Cp). We also study the T - X phase diagram of a two-component system of CH3CCl3+CCl4 using the Landau phenomenological model. Phase lines of the R+L (rhombohedral+liquid) and FCC+L (face-centred cubic + liquid) are calculated using the observed T - X phase diagram of this binary mixture. Our results show that the Landau mean field theory describes the observed behavior of CH3CCl3+CCl4 adequately. From the calculated T - X phase diagram, critical behavior of some thermodynamic quantities can be predicted at various temperatures and concentrations (CCl4) for a binary mixture of CH3CCl3+CCl4.

Molecular association of normal alkanoic acids with their thallium(I) salts: a new homologous series of fatty acid metal soaps.

PubMed

Fernández-García, M; García, M V; Redondo, M I; Cheda, J A; Fernández-García, M; Westrum, E F; Fernández-Martín, F

1997-02-01

A new homologous series of thallium(I) hydrogen dialkanoates, fatty acid thallium soaps, from the dipropane up to the ditetradecane is reported for the first time. This association with 1:1 stoichiometry is the only one exhibited by the thallium derivatives. They have been prepared by solidification of molten mixtures with equimolar proportions of acid and corresponding neutral salt, through crystallization from an anhydrous ethanolic solution of the mixture has also been successful in getting pure compounds with largest chain lengths. Vibrational spectroscopies clearly characterize these crystalline compounds as very strong hydrogen bonding systems. Assignations of active modes in proton and carbon nuclear magnetic resonance spectrometry (NMR) (in ethanol) and infrared (IR) and Raman spectra (in solid state) are reported. According to X-ray diffraction (XRD) they have monomolecular lamellar structures with the acyl chains arranged up and down to the cation/H-bond network in a methyl-to-methyl fashion, and vertically oriented to the basal plane. The acyl chains present all-trans conformation and alternating configuration (perpendicular orthorhombic subcell), like the beta'-phases of other kinds of lipids. Lamellar thickness is reported for the six room-temperature crystalline members. The molecular compounds present polymorphism, one crystal/crystal transition at temperatures close to the peritectical melting. Phase transition thermodynamics are also given and discussed with respect to their acid and salt parents. Their incongruent melting involves nearly 90% of the total enthalpic increments of both constituents' melting processes, making these compounds potential thermal energy storage materials.

Composition of the Cayley Formation at Apollo 16 as inferred from impact melt splashes

NASA Technical Reports Server (NTRS)

Morris, Richard V.; Horz, Friedrich; See, Thomas H.

1986-01-01

Abundances of major and trace elements and magnetic properties of 50 impact melt splashes (IMSs) from the Apollo 16 landing site are analzyed to determine the composition of their meteoritic component. MgO-Sc and Ca-Sc variation diagrams and least-squares mixing models are utilized to analyze the IMS, soil, and rock data. Consideration is given to progenitor lithologies of the IMS, the number of impact events represented by the IMS, and the heterogeneity of impact melts from single events. It is observed that the IMSs are composed of either a mixture of anorthosite and low-Sc impact melt rocks or anorthositic norite. It is determined that the surface Cayley layer is composed of TiO2, MgO, Sc, and La concentrations of 0.69, and 7.1 wt pct and 10.5 and 21.2 microg/g, respectively and 0.38 and 5.9 wt pct and 6.1 and 11.8 microg/g, respectively, for the subsurface Cayley layer. The Descartes Formation composition is estimated as TiO2, MgO, Sc, and La concentrations of 0.25, and 3.5 wt pct and 7.7 and 2.2 microg/g, respectively.

SiO(x) nanoparticles synthesized by an evaporation and condensation process using induction melting of silicon and gas injection.

PubMed

Jang, Bo Yun; Lee, Jin Seok; Kim, Joon Soo

2013-05-01

SiO(x) nanoparticles were synthesized using a specially designed induction melting system equipped with a segmented graphite crucible. The graphite crucible with the segmented wall was the key to enhancing the evaporation rate due to the increase of the evaporation area and convection of the silicon melt. Injection of the gas mixture of oxygen (O2) and argon (Ar) on silicon (Si) melt caused the formation of SiO(x) nanoparticles. The evaporated SiO(x) nanoparticles were then cooled and condensed in a process chamber. The effects of the O2/Ar ratio in the injection gas on the microstructures of the SiO(x) nanoparticles were then investigated. Synthesized SiO(x) nanoparticles were proven to be of a homogeneous amorphous phase with average diameters of 30-35 nm. The microstructures were independent from the O2/Ar ratio of the injected gas. However, x increased from 1.36 to 1.84 as the O2/Ar ratio increased. The purity of the synthesized nanoparticles was about 99.9%. SiO(x) nanoparticles could be applied as the active anode material in a lithium (Li) ion secondary battery.

Destabilization of yttria-stabilized zirconia induced by molten sodium vanadate-sodium sulfate melts

NASA Technical Reports Server (NTRS)

Nagelberg, A. S.; Hamilton, J. C.

1985-01-01

The extent of surface destabilization of ZrO2 - 8 wt percent Y2O3 ceramic disks was determined after exposure to molten salt mixtures of sodium sulfate containing up to 15 mole percent sodium metavanadate (NaVO3) at 1173 K. The ceramic surface was observed to transform from the cubic/tetragonal to monoclinic phase, concurrent with chemical changes in the molten salt layer in contact with the ceramic. Significant attack rates were observed in both pure sulfate and metavanadate sulfate melts. The rate of attack was found to be quite sensitive to the mole fraction of vanadate in the molten salt solution and the partial pressure of sulfur trioxide in equilibrium with the salt melt. The observed parabolic rate of attack is interpreted to be caused by a reaction controlled by diffusion in the salt that penetrates into the porous layer formed by the destabilization. The parabolic rate constant in mixed sodium metavanadate - sodium sulfate melts was found to be proportional to the SO3 partial pressure and the square of the metavanadate concentration. In-situ Raman spectroscopic measurements allowed simultaneous observations of the ceramic phases and salt chemistry during the attack process.

Potential genotoxic effects of melted snow from an urban area revealed by the Allium cepa test.

PubMed

Blagojević, Jelena; Stamenković, Gorana; Vujosević, Mladen

2009-09-01

The presence of well-known atmospheric pollutants is regularly screened for in large towns but knowledge about the effects of mixtures of different pollutants and especially their genotoxic potential is largely missing. Since falling snow collects pollutants from the air, melted snow samples could be suitable for evaluating potential genotoxicity. For this purpose the Allium cepa anaphase-telophase test was used to analyse melted snow samples from Belgrade, the capital city of Serbia. Samples of snow were taken at two sites, characterized by differences in pollution intensity, in three successive years. At the more polluted site the analyses showed a very high degree of both toxicity and genotoxicity in the first year of the study corresponding to the effects of the known mutagen used as the positive control. At the other site the situation was much better but not without warning signals. The results showed that standard analyses for the presence of certain contaminants in the air do not give an accurate picture of the possible consequences of urban air pollution because the genotoxic potential remains hidden. The A. cepa test has been demonstrated to be very convenient for evaluation of air pollution through analyses of melted snow samples.

Thermal analysis, phase equilibria, and superconducting properties in magnesium boride and carbon doped magnesium boride

NASA Astrophysics Data System (ADS)

Bohnenstiehl, Scot David

In this work, the low temperature synthesis of MgB2 from Mg/B and MgH2/B powder mixtures was studied using Differential Scanning Calorimetry (DSC). For the Mg/B powder mixture, two exothermic reaction events were observed and the first reaction event was initiated by the decomposition of Mg(OH)2 on the surface of the magnesium powder. For the MgH 2/B powder mixture, there was an endothermic event at ˜375 °C (the decomposition of MgH2 into H2 and Mg) and an exothermic event ˜600 °C (the reaction of Mg and B). The Kissinger analysis method was used to estimate the apparent activation energy of the Mg and B reaction using DSC data with different furnace ramp rates. The limitations of MgB2 low temperature synthesis led to the development of a high pressure induction furnace that was constructed using a pressure vessel and an induction heating power supply. The purpose was to not only synthesize more homogeneous MgB2 samples, but also to determine whether MgB2 melts congruently or incongruently. A custom implementation of the Smith Thermal Analysis method was developed and tested on aluminum and AlB2, the closest analogue to MgB2. Measurements on MgB2 powder and a high purity Mg/B elemental mixture confirmed that MgB2 melts incongruently and decomposes into a liquid and MgB4 at ˜1445 °C at 10 MPa via peritectic decomposition. Another measurement using a Mg/B elemental mixture with impure boron suggested that ˜0.7 wt% carbon impurity in the boron raised the incongruent melting temperature to ˜1490-1500 °C. Lastly, the solubility limit for carbon in MgB2 was studied by making samples from B4C and Mg at 1530 °C, 1600 °C and 1700 °C in the high pressure furnace. All three samples had three phases: Mg, MgB2C2, and carbon doped MgB2. The MgB 2C2 and carbon doped MgB2 grain size increased with temperature and the 1700 °C sample had needle-like grains for both phases. The presence of the ternary phase, MgB2C2, suggested that the maximum doping limit for carbon in MgB2 had been reached. The 1530 °C sample was characterized by Electron Probe Microanalysis at the University of Oregon and the average carbon concentration was estimated to be ˜5.9 at%. Further investigation using TEM found MgO inclusions in the 1530 °C sample which were not detected with X-ray diffraction.

Silicon in Mars' Core: A Prediction Based on Mars Model Using Nitrogen and Oxygen Isotopes in SNC Meteorites

NASA Technical Reports Server (NTRS)

Mohapatra, R. K.; Murty, S. V. S.

2002-01-01

Chemical and (oxygen) isotopic compositions of SNC meteorites have been used by a number of workers to infer the nature of precursor materials for the accretion of Mars. The idea that chondritic materials played a key role in the formation of Mars has been the central assumption in these works. Wanke and Dreibus have proposed a mixture of two types of chondritic materials, differing in oxygen fugacity but having CI type bulk chemical composition for the nonvolatile elements, for Mars' precursor. But a number of studies based on high pressure and temperature melting experiments do not favor a CI type bulk planet composition for Mars, as it predicts a bulk planet Fe/Si ratio much higher than that reported from the recent Pathfinder data. Oxygen forms the bulk of Mars (approximately 40% by wt.) and might provide clues to the type of materials that formed Mars. But models based on the oxygen isotopic compositions of SNC meteorites predict three different mixtures of precursor materials for Mars: 90% H + 10% CM, 85% H + 11% CV + 4% CI and 45% EH + 55% H. As each of these models has been shown to be consistent with the bulk geophysical properties (such as mean density, and moment of inertia factor) of Mars, the nature of the material that accreted to form Mars remains ambiguous.

No Martian soil component in shergottite meteorites

NASA Astrophysics Data System (ADS)

Barrat, J. A.; Jambon, A.; Ferrière, L.; Bollinger, C.; Langlade, J. A.; Liorzou, C.; Boudouma, O.; Fialin, M.

2014-01-01

We report on the major and trace element geochemistry of the impact melts contained in some shergottite meteorites. It has been previously proposed that some of these impact melts formed from a mixture of the host rock and a Martian soil component (e.g., Rao et al., 1999) or from partially weathered portions of the host rock (Chennaoui Aoudjehane et al., 2012). Our results contradict both of these theories. Trace element abundances of a glass pod from the EETA 79001A meteorite are identical to those of the host lithology, and indicate that no additional component is required in this case. The impact melts in Tissint share the same trace element features as the host rock, and no secondary phases produced by Martian secondary processes are involved. The light rare earth enrichments displayed by two small samples of Tissint (Chennaoui Aoudjehane et al., 2012) are possibly the result of some contamination of small stones on desert soil before the recovery of the meteorites.

Detection of plant oil DNA using high resolution melting (HRM) post PCR analysis: a tool for disclosure of olive oil adulteration.

PubMed

Vietina, Michelangelo; Agrimonti, Caterina; Marmiroli, Nelson

2013-12-15

Extra virgin olive oil is frequently subjected to adulterations with addition of oils obtained from plants other than olive. DNA analysis is a fast and economic tool to identify plant components in oils. Extraction and amplification of DNA by PCR was tested in olives, in milled seeds and in oils, to investigate its use in olive oil traceability. DNA was extracted from different oils made of hazelnut, maize, sunflower, peanut, sesame, soybean, rice and pumpkin. Comparing the DNA melting profiles in reference plant materials and in the oils, it was possible to identify any plant components in oils and mixtures of oils. Real-Time PCR (RT-PCR) platform has been added of the new methodology of high resolution melting (HRM), both were used to analyse olive oils mixed with different percentage of other oils. Results showed HRM a cost effective method for efficient detection of adulterations in olive oils. Copyright © 2013 Elsevier Ltd. All rights reserved.

Apollo 17 materials viewed from 2 to 4 mm soil particles: Pre-serenitatis highlands components

NASA Technical Reports Server (NTRS)

Jolliff, Bradley L.; Bishop, Kaylynn M.

1993-01-01

Among the highland lithologies of 2-4 mm rock fragments in North Massif soil 76503, we have found a compositional group, low in incompatible element concentrations, that we interpret as representing the pre-Serenitatis surface. A component of these materials is an igneous-textured lithology that we believe formed in large impact melts. These are compositionally similar to, and possibly precursors of, many of the granulitic breccias that appear to be mixtures of ferroan and magnesian-suite rocks. The polymict, or old, upper-crustal breccias, along with granulitic breccias and the endogenous igneous lithologies found particularly at the North Massif stations, constitute the poorly consolidated portions of North Massif. Highland samples from the South Massif, on the other hand, are enriched in materials of the competent, impact-melt breccias formed by the Serenitatis impact. The competent melt-breccias contain clasts of most of the pre-existing surface materials, but they also contain components not found in the rocks of the poorly consolidated massif materials.

Analysis of compressive strength in flatwise and edgewise direction to characterize Al-7000 aluminium foam

NASA Astrophysics Data System (ADS)

Sutarno, Soepriyanto, Syoni; Korda, Akhmad A.; Dirgantara, Tatacipta

2015-09-01

The physical mechanical properties of Al-7000 aluminium foam product and processing has been evaluated in this study. The characterization through the compressive testing refers to flatwise direction provided more confident result than edgewise direction. This experiment may correlate with formation of side products of calcia alumina and alumina silica that involved in metal mixture of aluminium foam. These compounds are formed from additional calcium carbonate and silica in the mixture. Calcium carbonate (CaCO3) roles as a blowing agent source of carbon dioxide (CO2). The formation of calcia alumina (CaO.Al2O3) may role to strengthen of cell wall of aluminium foam and to improve the viscosity of melting metal. The Al-7000 aluminium foam indicated a decrease of compressive strength probably due to existence of alumina silica (3Al2O3.SiO2) in the metal mixture.

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

PubMed

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.

Benard convection in binary mixtures with Soret effects and solidification

NASA Technical Reports Server (NTRS)

Zimmermann, G.; Mueller, U.; Davis, S. H.

1992-01-01

Benard convection was studied in a two-component liquid which displayed Soret effects (Soret, 1879; DeGroot and Mazur, 1969) and in which the temperatures of the horizontal boundaries spanned the solidification temperature of the mixture. A steady basic state was observed, in which the layer is partly liquid (near the lower, heated plate) and partly solid (near the upper, cooled plate) with the interface being planar, and in which all transport is by conduction and diffusion. Linear stability of the basic state was examined to determine how the presence of solid and the ability of the material to solidify or melt under disturbance affects the critical conditions from the onset of instability. The theoretical results obtained for cases when the phase change is absent and when the Soret effects are absent (but the phase change is present) are compared with an experiment using alcohol-water mixtures.

Treatment of refractory powders by a novel, high enthalpy dc plasma

NASA Astrophysics Data System (ADS)

Pershin, L.; Mitrasinovic, A.; Mostaghimi, J.

2013-06-01

Thermophysical properties of CO2-CH4 mixtures at high temperatures are very attractive for materials processing. In comparison with argon, at the same temperature, such a mixture possesses much higher enthalpy and higher thermal conductivity. At high temperatures, CO2-CH4 mixture has a complex composition with strong presence of CO which, in the case of powder treatment, could reduce oxidation. In this work, a dc plasma torch with graphite cathode was used to study the effect of plasma gas composition on spheroidization of tungsten carbide and alumina powders. Two different gas compositions were used to generate the plasma while the torch current was kept at 300 A. Various techniques were employed to assess the average concentration of carbides and oxides and the final shape of the treated powders. Process parameters such as input power and plasma gas composition allow controlling the degree of powder oxidation and spheroidization of high melting point ceramic powders.

Partitioning of Mg, Ca, and Na between carbonatite melt and hydrous fluid at 0.1-0.2 GPa

NASA Astrophysics Data System (ADS)

Veksler, Ilya V.; Keppler, Hans

Experimental studies of the element distribution between carbonatite melts and hydrous fluids are hampered by the fact that neither the fluid nor the melt can be isochemically quenched in conventional high-pressure vessels. In order to overcome this problem, we used a double-capsule technique to separate immiscible fluid and melt phases during and after the runs. The inner platinum capsules were charged with carbonate mixtures (CaCO3, MgCO3 and Na2CO3) and placed inside the outer capsules charged with distilled water and diamond powder. The latter was used as an inert trap for solids precipitating from the fluid on quenching. Carbonate melt and hydrous fluid equilibrated through a small hole left in the upper end of the inner capsule. The runs were performed in rapid-quench cold-seal pressure vessels at 0.1-0.2 GPa and 700-900°C in the two-phase (fluid+melt) stability region. Both quenched melt and quenched fluid were dissolved in dilute HCl and analysed by inductively coupled plasma atomic emission spectroscopy. The results show that under all conditions investigated, fluid/melt partition coefficients for Ca and Mg are similar and several times smaller than those for Na. At 0.1 GPa and a water/carbonatite ratio of 1 (by weight), the partition coefficients are DNa= 0.35+/- 0.02, DCa=0.09+/-0.02, and DMg=0.13+/- 0.01. Between 700 and 900°C, the effect of temperature on partitioning is negligible. However, DNa increases significantly with decreasing water/carbonatite ratio in the system. Our data show that the release of a hydrous fluid enriched in sodium and simultaneous crystallisation of calcite can transform an alkaline, vapour-saturated carbonatite melt into a body of pure calcite surrounded by zones of sodium metasomatism. Thus, it is quite possible that carbonate magmas with substantial amounts of alkalies were common parental liquids of plutonic carbonatites.

Copolymer Networks From Oligo(ε-caprolactone) and n-Butyl Acrylate Enable a Reversible Bidirectional Shape-Memory Effect at Human Body Temperature.

PubMed

Saatchi, Mersa; Behl, Marc; Nöchel, Ulrich; Lendlein, Andreas

2015-05-01

Exploiting the tremendous potential of the recently discovered reversible bidirectional shape-memory effect (rbSME) for biomedical applications requires switching temperatures in the physiological range. The recent strategy is based on the reduction of the melting temperature range (ΔT m ) of the actuating oligo(ε-caprolactone) (OCL) domains in copolymer networks from OCL and n-butyl acrylate (BA), where the reversible effect can be adjusted to the human body temperature. In addition, it is investigated whether an rbSME in the temperature range close or even above Tm,offset (end of the melting transition) can be obtained. Two series of networks having mixtures of OCLs reveal broad ΔTm s from 2 °C to 50 °C and from -10 °C to 37 °C, respectively. In cyclic, thermomechanical experiments the rbSME can be tailored to display pronounced actuation in a temperature interval between 20 °C and 37 °C. In this way, the application spectrum of the rbSME can be extended to biomedical applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Transient Interaction Between Reduction and Slagging Reactions of Wustite in Simulated Cohesive Zone of Blast Furnace

NASA Astrophysics Data System (ADS)

Ma, Kaihui; Xu, Jian; Deng, Junyi; Wang, Dongdong; Xu, Yang; Liao, Zhehan; Sun, Chengfeng; Zhang, Shengfu; Wen, Liangying

2018-06-01

The blast furnace cohesive zone plays an important role in the gas flow distribution and heat-transfer efficiency. Previous work mainly employed temperature-based indices to evaluate and predict the shape and thickness of the cohesive zone, whereas the internal reactions and related effects on the softening and melting properties of a complex burden are ignored. In this study, an innovative index, namely, shrinkage rate (SR), is first proposed to directly estimate the shrinkage behavior of wustite (FeO)-packed bed inside a simulated cohesive zone. The index is applied as the temperature increases to elucidate the transient interaction between reduction and slagging reactions. Results show that the thermally induced slagging reaction causes the packed bed to shrink at lower temperature, and the SR doubles when compounds with low melting temperature are generated by adding a reasonable concentration of CaO or SiO2. The reduction reaction becomes the driving force during the shrinkage of the packed bed between 1173 K and 1273 K when CO is introduced in the mixture gas. Then, the dominating factors for further shrinkage include slagging, reduction, or both factors. These factors vary with respect to the added compounds or temperature.

Glass Coats For Hot Isostatic Pressing

NASA Technical Reports Server (NTRS)

Ecer, Gunes M.

1989-01-01

Surface voids sealed from pressurizing gas. Coating technique enables healing of surface defects by hot isostatic pressing (HIP). Internal pores readily closed by HIP, but surface voids like cracks and pores in contact with pressurizing gas not healed. Applied to casting or weldment as thick slurry of two glass powders: one melts at temperature slightly lower than used for HIP, and another melts at higher temperature. For example, powder is glass of 75 percent SiO2 and 25 percent Na2O, while other powder SiO2. Liquid component of slurry fugitive organic binder; for example, mixture of cellulose acetate and acetone. Easy to apply, separates voids from surrounding gas, would not react with metal part under treatment, and easy to remove after pressing.

A TEM analysis of nanoparticulates in a Polar ice core

DOE Office of Scientific and Technical Information (OSTI.GOV)

Esquivel, E.V.; Murr, L.E

2004-03-15

This paper explores the prospect for analyzing nanoparticulates in age-dated ice cores representing times in antiquity to establish a historical reference for atmospheric particulate regimes. Analytical transmission electron microscope (TEM) techniques were utilized to observe representative ice-melt water drops dried down on carbon/formvar or similar coated grids. A 10,000-year-old Greenland ice core was melted, and representative water drops were transferred to coated grids in a clean room environment. Essentially, all particulates observed were aggregates and either crystalline or complex mixtures of nanocrystals. Especially notable was the observation of carbon nanotubes and related fullerene-like nanocrystal forms. These observations are similar withmore » some aspects of contemporary airborne particulates including carbon nanotubes and complex nanocrystal aggregates.« less

Thermal vacancies and phase separation in bcc mixtures of helium-3 and helium-4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fraass, Benedick Andrew

1980-01-01

Thermal vacancy concentrations in crystals of 3He- 4He mixtures have been determined. A new x-ray diffractometer-position sensitive detector system is used to make measurements of the absolute lattice parameter of the helium crystals with an accuracy of 300 ppM, and measurements of changes in lattice parameters to better than 60 ppM. The phase separation of the concentrated 3He- 4He mixtures has been studied in detail with the x-ray measurements. Vacancy concentrations in crystals with 99%, 51%, 28%, 12%, and 0% 3He have been determined. Phase separation has been studied in mixed crystals with concentrations of 51%, 28%, and 12% 3Hemore » and melting pressures between 3.0 and 6.1 MPa. The phase separation temperatures determined in this work are in general agreement with previous work. The pressure dependence of T c, the phase separation temperature for a 50% mixture, is found to be linear: dT c/dP = -34 mdeg/MPa. The x-ray measurements are used to make several comments on the low temperature phase diagram of the helium mixtures.« less

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

NASA Astrophysics Data System (ADS)

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.

Identification and quantification of virulence factors of enterotoxigenic Escherichia coli by high-resolution melting curve quantitative PCR.

PubMed

Wang, Weilan; Zijlstra, Ruurd T; Gänzle, Michael G

2017-05-15

Diagnosis of enterotoxigenic E. coli (ETEC) associated diarrhea is complicated by the diversity of E.coli virulence factors. This study developed a multiplex quantitative PCR assay based on high-resolution melting curves analysis (HRM-qPCR) to identify and quantify genes encoding five ETEC fimbriae related to diarrhea in swine, i.e. K99, F41, F18, F6 and K88. Five fimbriae expressed by ETEC were amplified in multiple HRM-qPCR reactions to allow simultaneous identification and quantification of five target genes. The assay was calibrated to allow quantification of the most abundant target gene, and validated by analysis of 30 samples obtained from piglets with diarrhea and healthy controls, and comparison to standard qPCR detection. The five amplicons with melting temperatures (Tm) ranging from 74.7 ± 0.06 to 80.5 ± 0.15 °C were well-separated by HRM-qPCR. The area of amplicons under the melting peak correlated linearly to the proportion of the template in the calibration mixture if the proportion exceeded 4.8% (K88) or <1% (all other amplicons). The suitability of the method was evaluated using 30 samples from weaned pigs aged 6-7 weeks; 14 of these animals suffered from diarrhea in consequence of poor sanitary conditions. Genes encoding fimbriae and enterotoxins were quantified by HRM-qPCR and/or qPCR. The multiplex HRM-qPCR allowed accurate analysis when the total gene copy number of targets was more than 1 × 10 5 / g wet feces and the HRM curves were able to simultaneously distinguish fimbriae genes in the fecal samples. The relative quantification of the most abundant F18 based on melting peak area was highly correlated (P < 0.001; r 2  = 0.956) with that of individual qPCR result but the correlation for less abundant fimbriae was much lower. The multiplex HRM assay identifies ETEC virulence factors specifically and efficiently. It correctly indicated the predominant fimbriae type and additionally provides information of presence/ absence of other fimbriae types and it could find broad applications for pathogen diagnosis.

NUCLEAR FUEL MATERIAL

DOEpatents

Goeddel, W.V.

1962-06-26

An improved method is given for making the carbides of nuclear fuel material. The metal of the fuel material, which may be a fissile and/or fertile material, is transformed into a silicide, after which the silicide is comminuted to the desired particle size. This silicide is then carburized at an elevated temperature, either above or below the melting point of the silicide, to produce an intimate mixture of the carbide of the fuel material and the carbide of silicon. This mixture of the fuel material carbide and the silicon carbide is relatively stable in the presence of moisture and does not exhibit the highly reactive surface condition which is observed with fuel material carbides made by most other known methods. (AEC)

Alkali-lead-iron phosphate glass and associated method

DOEpatents

Boatner, L.A.; Sales, B.C.; Franco, S.C.S.

1994-03-29

A glass composition and method of preparation utilizes a mixture consisting of phosphorus oxide within the range of about 40 to 49 molar percent, lead oxide within the range of about 10 to 25 molar percent, iron oxide within the range of about 10 to 17 molar percent and an alkali oxide within the range of about 23 to 30 molar percent. The glass resulting from the melting and subsequent solidifying of the mixture possesses a high degree of durability and a coefficient of thermal expansion as high as that of any of a number of metals. Such features render this glass highly desirable in glass-to-metal seal applications. 6 figures.

Temperature-Induced Transitions in the Structure and Interfacial Rheology of Human Meibum

PubMed Central

Leiske, Danielle L.; Leiske, Christopher I.; Leiske, Daniel R.; Toney, Michael F.; Senchyna, Michelle; Ketelson, Howard A.; Meadows, David L.; Fuller, Gerald G.

2012-01-01

Meibomian lipids are the primary component of the lipid layer of the tear film. Composed primarily of a mixture of lipids, meibum exhibits a range of melt temperatures. Compositional changes that occur with disease may alter the temperature at which meibum melts. Here we explore how the mechanical properties and structure of meibum from healthy subjects depend on temperature. Interfacial films of meibum were highly viscoelastic at 17°C, but as the films were heated to 30°C the surface moduli decreased by more than two orders of magnitude. Brewster angle microscopy revealed the presence of micron-scale inhomogeneities in meibum films at higher temperatures. Crystalline structure was probed by small angle x-ray scattering of bulk meibum, which showed evidence of a majority crystalline structure in all samples with lamellar spacing of 49 Å that melted at 34°C. A minority structure was observed in some samples with d-spacing at 110 Å that persisted up to 40°C. The melting of crystalline phases accompanied by a reduction in interfacial viscosity and elasticity has implications in meibum behavior in the tear film. If the melt temperature of meibum was altered significantly from disease-induced compositional changes, the resultant change in viscosity could alter secretion of lipids from meibomian glands, or tear-film stabilization properties of the lipid layer. PMID:22339874

Erythritol: crystal growth from the melt.

PubMed

Lopes Jesus, A J; Nunes, Sandra C C; Ramos Silva, M; Matos Beja, A; Redinha, J S

2010-03-30

The structural changes occurring on erythritol as it is cooled from the melt to low temperature, and then heated up to the melting point have been investigated by differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM), X-ray powder diffraction (PXRD) and Fourier transform infrared spectroscopy (FTIR). By DSC, it was possible to set up the conditions to obtain an amorphous solid, a crystalline solid, or a mixture of both materials in different proportions. Two crystalline forms have been identified: a stable and a metastable one with melting points of 117 and 104 degrees C, respectively. The fusion curve decomposition of the stable form revealed the existence of three conformational structures. The main paths of the crystallization from the melt were followed by PLTM. The texture and colour changes allowed the characterization of the different phases and transitions in which they are involved on cooling as well as on heating processes. The type of crystallization front and its velocity were also followed by microscopic observation. These observations, together with the data provided by PXRD, allowed elucidating the transition of the metastable form into the stable one. The structural changes occurring upon the cooling and subsequent heating processes, namely those arising from intermolecular hydrogen bonds, were also accompanied by infrared spectroscopy. Particular attention was given to the spectral changes occurring in the OH stretching region. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Planetesimal core formation with partial silicate melting using in-situ high P, high T, deformation x-ray microtomography

NASA Astrophysics Data System (ADS)

Anzures, B. A.; Watson, H. C.; Yu, T.; Wang, Y.

2017-12-01

Differentiation is a defining moment in formation of terrestrial planets and asteroids. Smaller planetesimals likely didn't reach high enough temperatures for widescale melting. However, we infer that core formation must have occurred within a few million years from Hf-W dating. In lieu of a global magma ocean, planetesimals likely formed through inefficient percolation. Here, we used in-situ high temperature, high pressure, x-ray microtomography to track the 3-D evolution of the sample at mantle conditions as it underwent shear deformation. Lattice-Boltzmann simulations for permeability were used to characterize the efficiency of melt percolation. Mixtures of KLB1 peridotite plus 6.0 to 12.0 vol% FeS were pre-sintered to achieve an initial equilibrium microstructure, and then imaged through several consecutive cycles of heating and deformation. The maximum calculated melt segregation velocity was found to be 0.37 cm/yr for 6 vol.% FeS and 0.61 cm/year for 12 vol.% FeS, both below the minimum velocity of 3.3 cm/year required for a 100km planetesimal to fully differentiate within 3 million years. However, permeability is also a function of grain size and thus the samples having smaller grains than predicted for small planetesimals could have contributed to low permeability and also low migration velocity. The two-phase (sulfide melt and silicate melt) flow at higher melt fractions (6 vol.% and 12 vol.% FeS) was an extension of a similar study1 containing only sulfide melt at lower melt fraction (4.5 vol.% FeS). Contrary to the previous study, deformation did result in increased permeability until the sample was sheared by twisting the opposing Drickamer anvils by 360 degrees. Also, the presence of silicate melt caused the FeS melt to coalesce into less connected pathways as the experiment with 6 vol.% FeS was found to be less permeable than the one with 4.5 vol.% FeS but without any partial melt. The preliminary data from this study suggests that impacts as well as higher temperature leading to partial melting of the silicate portion of the mantle could have contributed to fast enough core formation. 1. Todd, K.A., Watson, H.C., Yu, T., Wang, Y., American Mineralogist, 101.9, 1996-2004, 2016

Adiabatic temperature changes of magma-gas mixtures during ascent and eruption

USGS Publications Warehouse

Mastin, L.G.; Ghiorso, M.S.

2001-01-01

Most quantitative studies of flow dynamics in eruptive conduits during volcanic eruptions use a simplified energy equation that ignores either temperature changes, or the thermal effects of gas exsolution. In this paper we assess the effects of those simplifications by analyzing the influence of equilibrium gas exsolution and expansion on final temperatures, velocities, and liquid viscosities of magma-gas mixtures during adiabatic decompression. For a given initial pressure (p1), temperature (T1) and melt composition, the final temperature (Tf) and velocity (Umax) will vary depending on the degree to which friction and other irreversible processes reduce mechanical energy within the conduit. The final conditions range between two thermodynamic end members: (1) Constant enthalpy (dh=0), in which Tf is maximal and no energy goes into lifting or acceleration; and (2) constant entropy (ds=0), in which Tf is minimal and maximum energy goes into lifting and acceleration. For ds=0, T1=900 ??C and p1=200 MPa, a water-saturated albitic melt cools by ???200 ??C during decompression, but only about 250 ??C of this temperature decrease can be attributed to the energy of gas exsolution per se: The remainder results from expansion of gas that has already exsolved. For the same T1 and p1, and dh=0, Tf is 10-15 ??C hotter than T1 but is about 10-25 ??C cooler than Tf in similar calculations that ignore the energy of gas exsolution. For ds=0, p1=200 MPa and T1= 9,000 ??C, assuming that all the enthalpy change of decompression goes into kinetic energy, a water-saturated albitic mixture can theoretically accelerate to ???800 m/s. Similar calculations that ignore gas exsolution (but take into account gas expansion) give velocities about 10-15% higher. For the same T1, p1 = 200 MPa, and ds = 0, the cooling associated with gas expansion and exsolution increases final melt viscosity more than 2.5 orders of magnitude. For dh = 0, isenthalpic heating decreases final melt viscosity by about 0.7 orders of magnitude. Thermal effects of gas exsolution are responsible for less than 10% of these viscosity changes. Isenthalpic heating could significantly reduce flow resistance in eruptive conduits if heat generation were concentrated along conduit walls, where shearing is greatest. Isentropic cooling could enhance clast fragmentation in near-surface vents in cases where extremely rapid pressure drops reduce gas temperatures and chill the margins of expanding pyroclasts.

Phase Diagram for a Four-Component System of Pentanedioic, Hexanedioic, Nonanedioic, and Decanedioic Acids

NASA Astrophysics Data System (ADS)

Kolyado, A. V.; Alenova, S. M.; Garkushin, I. K.

2018-05-01

Phase equilibria in a four-component system of pentanedioic, hexanedioic, nonanedioic, and decanedioic acids are studied via differential thermal analysis. The determined eutectic composition is pentanedioic acid, 48.1 wt %; hexanedioic acid, 10.0 wt %; nonanedioic acid, 25.7 wt %; and decanedioic acid, 16.2 wt %. The melting point of the eutectic mixture is 63.1°C.

ELECTROLYTIC PROCESS FOR PRODUCING METALS

DOEpatents

Kopelman, B.; Holden, R.B.

1961-06-01

A method is described for reducing beryllium halides to beryllium. The beryllfum halide fs placed in an eutectic mixture of alkali halides and alkaline earth halides. The constituents of this eutectic bath are so chosen that it has a melting point less than the boiling point of mercury, which acts as a cathode for the system. The beryllium metal is then deposited in the mercury upon electrolysis.

Measurement of the diffusion coefficient of acetone in succinonitrile at its melting point

NASA Technical Reports Server (NTRS)

Chopra, M. A.; Glicksman, M. E.; Singh, N. B.

1988-01-01

The diffusion coefficient of acetone in liquid succinonitrile at 331.1 K was determined using the method of McBain and Dawson (1935). Only dilute mixtures of SCN-acetone were studied. The interdiffusion constant was determined to be 0.0000127 sq cm/s and was essentially independent of the acetone concentration over the range investigated (0.5 to 18 mol pct acetone).

Effect of PCM on the Hydration Process of Cement-Based Mixtures: A Novel Thermo-Mechanical Investigation.

PubMed

Fabiani, Claudia; Pisello, Anna Laura; D'Alessandro, Antonella; Ubertini, Filippo; Cabeza, Luisa F; Cotana, Franco

2018-05-23

The use of Phase Change Material (PCM) for improving building indoor thermal comfort and energy saving has been largely investigated in the literature in recent years, thus confirming PCM’s capability to reduce indoor thermal fluctuation in both summer and winter conditions, according to their melting temperature and operation boundaries. Further to that, the present paper aims at investigating an innovative use of PCM for absorbing heat released by cement during its curing process, which typically contributes to micro-cracking of massive concrete elements, therefore compromising their mechanical performance during their service life. The experiments carried out in this work showed how PCM, even in small quantities (i.e., up to 1% in weight of cement) plays a non-negligible benefit in reducing differential thermal increases between core and surface and therefore mechanical stresses originating from differential thermal expansion, as demonstrated by thermal monitoring of cement-based cubes. Both PCM types analyzed in the study (with melting temperatures at 18 and 25 ∘ C) were properly dispersed in the mix and were shown to be able to reduce the internal temperature of the cement paste by several degrees, i.e., around 5 ∘ C. Additionally, such small amount of PCM produced a reduction of the final density of the composite and an increase of the characteristic compressive strength with respect to the plain recipe.

Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

PubMed Central

Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

2011-01-01

Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified. PMID:22319402

Effects of calcination temperature and acid-base properties on mixed potential ammonia sensors modified by metal oxides.

PubMed

Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

2011-01-01

Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO(3), Bi(2)O(3) and V(2)O(5), while the use of WO(3,) Nb(2)O(5) and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO(3) > Bi(2)O(3) > V(2)O(5), which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

Highly conductive solid polymer electrolyte membranes based on polyethylene glycol-bis-carbamate dimethacrylate networks

NASA Astrophysics Data System (ADS)

Fu, Guopeng; Dempsey, Janel; Izaki, Kosuke; Adachi, Kaoru; Tsukahara, Yasuhisa; Kyu, Thein

2017-08-01

In an effort to fabricate highly conductive, stable solid-state polymer electrolyte membranes (PEM), polyethylene glycol bis-carbamate (PEGBC) was synthesized via condensation reaction between polyethylene glycol diamine and ethylene carbonate. Subsequently, dimethacrylate groups were chemically attached to both ends of PEGBC to afford polyethylene glycol-bis-carbamate dimethacrylate (PEGBCDMA) precursor having crosslinking capability. The melt-mixed ternary mixtures consisting of PEGBCDMA, succinonitrile plasticizer, and lithium trifluorosulphonyl imide salt were completely miscible in a wide compositional range. Upon photo-crosslinking, the neat PEGBCDMA network was completely amorphous exhibiting higher tensile strength, modulus, and extensibility relative to polyethylene glycol diacrylate (PEGDA) counterpart. Likewise, the succinonitrile-plasticized PEM network containing PEGBCDMA remained completely amorphous and transparent upon photo-crosslinking, showing superionic conductivity, improved thermal stability, and superior tensile properties with improved capacity retention during charge/discharge cycling as compared to the PEGDA-based PEM.

Solubility, Partitioning, and Speciation of Carbon in Shallow Magma Oceans of Terrestrial Planets Constrained by High P-T Experiments

NASA Astrophysics Data System (ADS)

Chi, H.; Dasgupta, R.; Shimizu, N.

2011-12-01

Deep planetary volatile cycles have a critical influence on planetary geodynamics, atmospheres, climate, and habitability. However, the initial conditions that prevailed in the early, largely molten Earth and other terrestrial planets, in terms of distribution of volatiles between various reservoirs - metals, silicates, and atmosphere - remains poorly constrained. Here we investigate the solubility, partitioning, and speciation of carbon-rich volatile species in a shallow magma ocean environment, i.e., in equilibrium with metallic and silicate melts. A series of high pressure-temperature experiments using a piston cylinder apparatus were performed at 1-3 GPa, 1500-1800 °C on synthetic basaltic mixtures + Fe-Ni metal powders contained in graphite capsules. All the experiments produced glassy silicate melt pool in equilibrium with quenched metal melt composed of dendrites of cohenite and kamacite. Major element compositions of the resulting phases and the carbon content of metallic melts were analyzed by EPMA at NASA-JSC. Carbon and hydrogen concentrations of basaltic glasses were determined using Cameca IMS 1280 SIMS at WHOI and speciation of dissolved volatiles was constrained using FTIR and Raman spectroscopy at Rice University. Based on the equilibria - FeO (silicate melt) = Fe (metal alloy melt) + 1/2O2, we estimate the oxygen fugacity of our experiments in the range of ΔIW of -1 to -2. FTIR analysis on doubly polished basaltic glass chips suggests that the concentrations of dissolved CO32- or molecular CO2 are negligible in graphite and metal saturated reduced conditions, whereas the presence of dissolved OH- is evident from the asymmetric peak at 3500 cm-1. Collected Raman spectra of basaltic glasses in the frequency range of 200-4200 cm-1 suggest that hydrogen is present both as dissolved OH- species (band at 3600 cm-1) and as molecular H2 (band near 4150 cm-1) for all of our experiments. Faint peaks near 2915 cm-1 and consistent peaks near 740 cm-1 suggest that possible carbon species in our reduced glasses are likely minor CH4 and Si-C, respectively and are consistent with the recent solubility studies at reduced conditions [1,2]. Carbon solubility (calibrated using 12C/30Si) at graphite saturation in our reduced basaltic glasses is only in the range 20-100 ppm C, with H2O contents in the range of 0.2-0.7 wt.%. In contrast to the low dissolved carbon concentration in the basaltic silicate melts, carbon solubility in quenched metallic melts vary in the range of 5-7 wt.%. Our preliminary work indicates that the solubility of carbon in reduced basaltic melts relevant for early magma conditions may be several orders of magnitude lower compared to the solubility of carbon in modern terrestrial basalts. This coupled with significant solubility of carbon in Fe-Ni metallic melt suggests that most of magma ocean carbon was likely partitioned into deep metallic melts. Further metal-silicate experiments with more depolymerized basaltic melts of variable compositions are underway and will be presented. [1] Kadik et al. JPetrol 45, 1297-1310, 2004; [2] Kadik et al. Geochem Int 44, 33-47, 2006.

Effect of Mantle Wedge Hybridization by Sediment Melt on Geochemistry of Arc Magma and Arc Mantle Source - Insights from Laboratory Experiments at High Pressures and Temperatures

NASA Astrophysics Data System (ADS)

Mallik, A.; Dasgupta, R.; Tsuno, K.; Nelson, J. M.

2015-12-01

Generation of arc magmas involves metasomatism of the mantle wedge by slab-derived H2O-rich fluids and/or melts and subsequent melting of the modified source. The chemistry of arc magmas and the residual mantle wedge are not only regulated by the chemistry of the slab input, but also by the phase relations of metasomatism or hybridization process in the wedge. The sediment-derived silica-rich fluids and hydrous partial melts create orthopyroxene-rich zones in the mantle wedge, due to reaction of mantle olivine with silica in the fluid/melt [1,2]. Geochemical evidence for such a reaction comes from pyroxenitic lithologies coexisting with peridotite in supra-subduction zones. In this study, we have simulated the partial melting of a parcel of mantle wedge modified by bulk addition of sediment-derived melt with variable H2O contents to investigate the major and trace element chemistry of the magmas and the residues formed by this process. Experiments at 2-3 GPa and 1150-1300 °C were conducted on mixtures of 25% sediment-derived melt and 75% lherzolite, with bulk H2O contents varying from 2 to 6 wt.%. Partial reactive crystallization of the rhyolitic slab-derived melt and partial melting of the mixed source produced a range of melt compositions from ultra-K basanites to basaltic andesites, in equilibrium with an orthopyroxene ± phlogopite ± clinopyroxene ± garnet bearing residue, depending on P and bulk H2O content. Model calculations using partition coefficients (from literature) of trace elements between experimental minerals and silicate melt suggest that the geochemical signatures of the slab-derived melt, such as low Ce/Pb and depletion in Nb and Ta (characteristic slab signatures) are not erased from the resulting melt owing to reactive crystallization. The residual mineral assemblage is also found to be similar to the supra-subduction zone lithologies, such as those found in Dabie Shan (China) and Sanbagawa Belt (Japan). In this presentation, we will also compare the major and trace element characteristics of bulk rock and minerals found in orthopyroxenites from supra-subduction zones with the residua formed in our experiments, to differentiate between melt versus fluid, and sediment- versus basalt-derived flux in the mantle wedge. [1] Mallik et al. (2015) CMP169(5) [2] Sekine & Wyllie (1982) CMP 81(3)

MeltMigrator: A MATLAB-based software for modeling three-dimensional melt migration and crustal thickness variations at mid-ocean ridges following a rules-based approach

NASA Astrophysics Data System (ADS)

Bai, Hailong; Montési, Laurent G. J.; Behn, Mark D.

2017-01-01

MeltMigrator is a MATLAB®-based melt migration software developed to process three-dimensional mantle temperature and velocity data from user-supplied numerical models of mid-ocean ridges, calculate melt production and melt migration trajectories in the mantle, estimate melt flux along plate boundaries, and predict crustal thickness distribution on the seafloor. MeltMigrator is also capable of calculating compositional evolution depending on the choice of petrologic melting model. Programmed in modules, MeltMigrator is highly customizable and can be expanded to a wide range of applications. We have applied it to complex mid-ocean ridge model settings, including transform faults, oblique segments, ridge migration, asymmetrical spreading, background mantle flow, and ridge-plume interaction. In this technical report, we include an example application to a segmented mid-ocean ridge. MeltMigrator is available as a supplement to this paper, and it is also available from GitHub and the University of Maryland Geodynamics Group website.

Glass-ceramic from mixtures of bottom ash and fly ash.

PubMed

Vu, Dinh Hieu; Wang, Kuen-Sheng; Chen, Jung-Hsing; Nam, Bui Xuan; Bac, Bui Hoang

2012-12-01

Along with the gradually increasing yield of the residues, appropriate management and treatment of the residues have become an urgent environmental protection problem. This work investigated the preparation of a glass-ceramic from a mixture of bottom ash and fly ash by petrurgic method. The nucleation and crystallization kinetics of the new glass-ceramic can be obtained by melting the mixture of 80% bottom ash and 20% fly ash at 950 °C, which was then cooled in the furnace for 1h. Major minerals forming in the glass-ceramics mainly are gehlenite (Ca(2)Al(2)SiO(7)) & akermanite (Ca(2)MgSiO(7)) and wollastonite (CaSiO(3)). In addition, regarding chemical/mechanical properties, the chemical resistance showing durability, and the leaching concentration of heavy metals confirmed the possibility of engineering and construction applications of the most superior glass-ceramic product. Finally, petrurgic method of a mixture of bottom ash and fly ash at 950 °C represents a simple, inexpensive, and energy saving method compared with the conventional heat treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Structure of phospholipid-cholesterol membranes: an x-ray diffraction study.

PubMed

Karmakar, Sanat; Raghunathan, V A

2005-06-01

We have studied the phase behavior of mixtures of cholesterol with dipalmitoyl phosphatidylcholine (DPPC), dimyristoyl phosphatidylcholine (DMPC), and dilauroyl phosphatidylethanolamine (DLPE), using x-ray diffraction techniques. Phosphatidylcholine (PC)-cholesterol mixtures are found to exhibit a modulated phase for cholesterol concentrations around 15 mol % at temperatures below the chain melting transition. Lowering the relative humidity from 98% to 75% increases the temperature range over which it exists. An electron density map of this phase in DPPC-cholesterol mixtures, calculated from the x-ray diffraction data, shows bilayers with a periodic height modulation, as in the ripple phase observed in many PCs in between the main- and pretransitions. However, these two phases differ in many aspects, such as the dependence of the modulation wavelength on the cholesterol content and thermodynamic stability at reduced humidities. This modulated phase is found to be absent in DLPE-cholesterol mixtures. At higher cholesterol contents the gel phase does not occur in any of these three systems, and the fluid lamellar phase is observed down to the lowest temperature studied (5 degrees C).

Use of the Flory-Huggins theory to predict the solubility of nifedipine and sulfamethoxazole in the triblock, graft copolymer Soluplus.

PubMed

Altamimi, Mohammad A; Neau, Steven H

2016-01-01

Drug dispersed in a polymer can improve bioavailability; dispersed amorphous drug undergoes recrystallization. Solid solutions eliminate amorphous regions, but require a measure of the solubility. Use the Flory-Huggins Theory to predict crystalline drugs solubility in the triblock, graft copolymer Soluplus® to provide a solid solution. Physical mixtures of the two drugs with similar melting points but different glass forming ability, sulfamethoxazole and nifedipine, were prepared with Soluplus® using a quick technique. Drug melting point depression (MPD) was measured using differential scanning calorimetry. The Flory-Huggins Theory allowed: (1) interaction parameter, χ, calculation using MPD data to provide a measure of drug-polymer interaction strength and (2) estimation of the free energy of mixing. A phase diagram was constructed with the MPD data and glass transition temperature (Tg) curves. The interaction parameters with Soluplus® and the free energy of mixing were estimated. Drug solubility was calculated by the intersection of solubility equations and that of MPD and Tg curves in the phase diagram. Negative interaction parameters indicated strong drug-polymer interactions. The phase diagram and solubility equations provided comparable solubility estimates for each drug in Soluplus®. Results using the onset of melting rather than the end of melting support the use of the onset of melting. The Flory-Huggins Theory indicates that Soluplus® interacts effectively with each drug, making solid solution formation feasible. The predicted solubility of the drugs in Soluplus® compared favorably across the methods and supports the use of the onset of melting.

Use of the Flory-Huggins theory to predict the solubility of nifedipine and sulfamethoxazole in the triblock, graft copolymer Soluplus.

PubMed

Altamimi, Mohammad A; Neau, Steven H

2016-03-01

Drug dispersed in a polymer can improve bioavailability; dispersed amorphous drug undergoes recrystallization. Solid solutions eliminate amorphous regions, but require a measure of the solubility. Use the Flory-Huggins Theory to predict crystalline drugs solubility in the triblock, graft copolymer Soluplus® to provide a solid solution. Physical mixtures of the two drugs with similar melting points but different glass forming ability, sulfamethoxazole and nifedipine, were prepared with Soluplus® using a quick technique. Drug melting point depression (MPD) was measured using differential scanning calorimetry. The Flory-Huggins Theory allowed: (1) interaction parameter, χ, calculation using MPD data to provide a measure of drug-polymer interaction strength and (2) estimation of the free energy of mixing. A phase diagram was constructed with the MPD data and glass transition temperature (T g ) curves. The interaction parameters with Soluplus® and the free energy of mixing were estimated. Drug solubility was calculated by the intersection of solubility equations and that of MPD and T g curves in the phase diagram. Negative interaction parameters indicated strong drug-polymer interactions. The phase diagram and solubility equations provided comparable solubility estimates for each drug in Soluplus®. Results using the onset of melting rather than the end of melting support the use of the onset of melting. The Flory-Huggins Theory indicates that Soluplus® interacts effectively with each drug, making solid solution formation feasible. The predicted solubility of the drugs in Soluplus® compared favorably across the methods and supports the use of the onset of melting.

EvOligo: A Novel Software to Design and Group Libraries of Oligonucleotides Applicable for Nucleic Acid-Based Experiments.

PubMed

Milewski, Marek C; Kamel, Karol; Kurzynska-Kokorniak, Anna; Chmielewski, Marcin K; Figlerowicz, Marek

2017-10-01

Experimental methods based on DNA and RNA hybridization, such as multiplex polymerase chain reaction, multiplex ligation-dependent probe amplification, or microarray analysis, require the use of mixtures of multiple oligonucleotides (primers or probes) in a single test tube. To provide an optimal reaction environment, minimal self- and cross-hybridization must be achieved among these oligonucleotides. To address this problem, we developed EvOligo, which is a software package that provides the means to design and group DNA and RNA molecules with defined lengths. EvOligo combines two modules. The first module performs oligonucleotide design, and the second module performs oligonucleotide grouping. The software applies a nearest-neighbor model of nucleic acid interactions coupled with a parallel evolutionary algorithm to construct individual oligonucleotides, and to group the molecules that are characterized by the weakest possible cross-interactions. To provide optimal solutions, the evolutionary algorithm sorts oligonucleotides into sets, preserves preselected parts of the oligonucleotides, and shapes their remaining parts. In addition, the oligonucleotide sets can be designed and grouped based on their melting temperatures. For the user's convenience, EvOligo is provided with a user-friendly graphical interface. EvOligo was used to design individual oligonucleotides, oligonucleotide pairs, and groups of oligonucleotide pairs that are characterized by the following parameters: (1) weaker cross-interactions between the non-complementary oligonucleotides and (2) more uniform ranges of the oligonucleotide pair melting temperatures than other available software products. In addition, in contrast to other grouping algorithms, EvOligo offers time-efficient sorting of paired and unpaired oligonucleotides based on various parameters defined by the user.

Global approach for the validation of an in-line Raman spectroscopic method to determine the API content in real-time during a hot-melt extrusion process.

PubMed

Netchacovitch, L; Thiry, J; De Bleye, C; Dumont, E; Cailletaud, J; Sacré, P-Y; Evrard, B; Hubert, Ph; Ziemons, E

2017-08-15

Since the Food and Drug Administration (FDA) published a guidance based on the Process Analytical Technology (PAT) approach, real-time analyses during manufacturing processes are in real expansion. In this study, in-line Raman spectroscopic analyses were performed during a Hot-Melt Extrusion (HME) process to determine the Active Pharmaceutical Ingredient (API) content in real-time. The method was validated based on a univariate and a multivariate approach and the analytical performances of the obtained models were compared. Moreover, on one hand, in-line data were correlated with the real API concentration present in the sample quantified by a previously validated off-line confocal Raman microspectroscopic method. On the other hand, in-line data were also treated in function of the concentration based on the weighing of the components in the prepared mixture. The importance of developing quantitative methods based on the use of a reference method was thus highlighted. The method was validated according to the total error approach fixing the acceptance limits at ±15% and the α risk at ±5%. This method reaches the requirements of the European Pharmacopeia norms for the uniformity of content of single-dose preparations. The validation proves that future results will be in the acceptance limits with a previously defined probability. Finally, the in-line validated method was compared with the off-line one to demonstrate its ability to be used in routine analyses. Copyright © 2017 Elsevier B.V. All rights reserved.

Thermal analysis and FTIR spectral curve-fitting investigation of formation mechanism and stability of indomethacin-saccharin cocrystals via solid-state grinding process.

PubMed

Zhang, Gang-Chun; Lin, Hong-Liang; Lin, Shan-Yang

2012-07-01

The cocrystal formation of indomethacin (IMC) and saccharin (SAC) by mechanical cogrinding or thermal treatment was investigated. The formation mechanism and stability of IMC-SAC cocrystal prepared by cogrinding process were explored. Typical IMC-SAC cocrystal was also prepared by solvent evaporation method. All the samples were identified and characterized by using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) microspectroscopy with curve-fitting analysis. The physical stability of different IMC-SAC ground mixtures before and after storage for 7 months was examined. The results demonstrate that the stepwise measurements were carried out at specific intervals over a continuous cogrinding process showing a continuous growth in the cocrystal formation between IMC and SAC. The main IR spectral shifts from 3371 to 3,347 cm(-1) and 1693 to 1682 cm(-1) for IMC, as well as from 3094 to 3136 cm(-1) and 1718 to 1735 cm(-1) for SAC suggested that the OH and NH groups in both chemical structures were taken part in a hydrogen bonding, leading to the formation of IMC-SAC cocrystal. A melting at 184 °C for the 30-min IMC-SAC ground mixture was almost the same as the melting at 184 °C for the solvent-evaporated IMC-SAC cocrystal. The 30-min IMC-SAC ground mixture was also confirmed to have similar components and contents to that of the solvent-evaporated IMC-SAC cocrystal by using a curve-fitting analysis from IR spectra. The thermal-induced IMC-SAC cocrystal formation was also found to be dependent on the temperature treated. Different IMC-SAC ground mixtures after storage at 25 °C/40% RH condition for 7 months had an improved tendency of IMC-SAC cocrystallization. Copyright © 2012 Elsevier B.V. All rights reserved.

Melt migration modeling in partially molten upper mantle

NASA Astrophysics Data System (ADS)

Ghods, Abdolreza

The objective of this thesis is to investigate the importance of melt migration in shaping major characteristics of geological features associated with the partial melting of the upper mantle, such as sea-floor spreading, continental flood basalts and rifting. The partial melting produces permeable partially molten rocks and a buoyant low viscosity melt. Melt migrates through the partially molten rocks, and transfers mass and heat. Due to its much faster velocity and appreciable buoyancy, melt migration has the potential to modify dynamics of the upwelling partially molten plumes. I develop a 2-D, two-phase flow model and apply it to investigate effects of melt migration on the dynamics and melt generation of upwelling mantle plumes and focusing of melt migration beneath mid-ocean ridges. Melt migration changes distribution of the melt-retention buoyancy force and therefore affects the dynamics of the upwelling plume. This is investigated by modeling a plume with a constant initial melt of 10% where no further melting is considered. Melt migration polarizes melt-retention buoyancy force into high and low melt fraction regions at the top and bottom portions of the plume and therefore results in formation of a more slender and faster upwelling plume. Allowing the plume to melt as it ascends through the upper mantle also produces a slender and faster plume. It is shown that melt produced by decompressional melting of the plume migrates to the upper horizons of the plume, increases the upwelling velocity and thus, the volume of melt generated by the plume. Melt migration produces a plume which lacks the mushroom shape observed for the plume models without melt migration. Melt migration forms a high melt fraction layer beneath the sloping base of the impermeable oceanic lithosphere. Using realistic conditions of melting, freezing and melt extraction, I examine whether the high melt fraction layer is able to focus melt from a wide partial melting zone to a narrow region beneath the observed neo-volcanic zone. My models consist of three parts; lithosphere, asthenosphere and a melt extraction region. It is shown that melt migrates vertically within the asthenosphere, and forms a high melt fraction layer beneath the sloping base of the impermeable lithosphere. Within the sloping high melt fraction layer, melt migrates laterally towards the ridge. In order to simulate melt migration via crustal fractures and cracks, melt is extracted from a melt extraction region extending to the base of the crust. Performance of the melt focusing mechanism is not significantly sensitive to the size of melt extraction region, melt extraction threshold and spreading rate. In all of the models, about half of the total melt production freezes beneath the cooling base of the lithosphere, and the rest is effectively focused towards the ridge and forms the crust. To meet the computational demand for a precise tracing of the deforming upwelling plume and including the chemical buoyancy of the partially molten zone in my models, a new numerical method is developed to solve the related pure advection equations. The numerical method is based on Second Moment numerical method of Egan and Mahoney [1972] which is improved to maintain a high numerical accuracy in shear and rotational flow fields. In comparison with previous numerical methods, my numerical method is a cost-effective, non-diffusive and shape preserving method, and it can also be used to trace a deforming body in compressible flow fields.

The development of the cell cryopreservation protocol with controlled rate thawing.

PubMed

Gurina, Tatyana M; Pakhomov, Alexandr V; Polyakova, Anna L; Legach, Evgeniy I; Bozhok, Galyna A

2016-06-01

Thawing in the water bath is often considered as a standard procedure. The thermal history of samples thawed in this way is poorly controlled, but cryopreservation and banking of cell-based products require standardization, automation and safety of all the technological stages including thawing. The programmable freezers allow implementation of the controlled cooling as well as the controlled thawing. As the cell damage occurs during the phase transformation that takes place in the cryoprotectant medium in the process of freezing-thawing, the choice of warming rates within the temperature intervals of transformations is very important. The goal of the study was to investigate the influence of warming rates within the intervals of the phase transformations in the DMSO-based cryoprotectant medium on the cell recovery and to develop a cryopreservation protocol with controlled cooling and warming rates. The temperature intervals of phase transformations such as melting of the eutectic mixture of the cryoprotectant solution (MEMCS), melting of the eutectic salt solution (MESS), melting of the main ice mass (MMIM), recrystallization before MEMCS, recrystallization before MESS and recrystallization before MMIM were determined by thermo-mechanical analysis. The biological experiments were performed on the rat testicular interstitial cells (TIC). The highest levels of the cell recovery and metabolic activity after cryopreservation were obtained using the protocol with the high (20 °C/min) warming rate in the temperature intervals of crystallization of the eutectics as well as recrystallizations and the low (1 °C/min) warming rate in the temperature intervals of melting of the eutectics as well as MMIM. The total cell recovery was 65.3 ± 2.1 %, the recovery of the 3-beta-HSD-positive (Leydig) cells was 82.9 ± 1.8 %, the MTT staining was 32.5 ± 0.9 % versus 42.1 ± 1.7 %; 57.4 ± 2.1 % and 24.0 ± 1.1 % respectively, when compared to the thawing in the water bath.

Modeling the Time-dependent Changes in Electrical Conductivity of Basaltic Melts With Redox State

NASA Astrophysics Data System (ADS)

Pommier, A.; Gaillard, F.; Pichavant, M.

2008-12-01

The electrical conductivity σ is an efficient probe of mass transfer processes within silicate melts and magmas. Little attention has been given to the influence of redox state (fO2) on the melts conductivity. We present an experimental setup allowing electrical conductivity measurements for basaltic melts under variable fO2. We demonstrate a significant dependence of σ with fO2, allowing to characterize in situ the mechanisms and kinetics of redox changes in the melt. Experiments were conducted on basalts from Pu'u 'O'o, Hawaii, and Mt.Vesuvius, Italy. Measurements were performed cylindrical glass samples (OD: 6mm, ID: 1mm, L: 8mm) using an impedance spectrometer. Experiments were conducted in a 1atm vertical furnace, from 1200°C to 1400°C. Variable gas atmosphere (air, CO2 or CO-CO2 gas mixtures) were used, imposing ΔNNO from -1 to +7. Electrical conductivities were determined for the two melts at constant fO2, different T (constant fO2) and constant T, different fO2 (variable fO2) obtained by changing the gas composition. Isothermal reduction and oxidation cycles were performed. Glasses quenched from different T and fO2 conditions were analyzed by electron microprobe, the FeO concentration was determined by wet chemistry. In constant fO2 experiments, a small but detectable effect of fO2 on σ is evidenced. At 1300°C, the difference in the Kilauea sample conductivity between reduced (ΔNNO=-1) and oxidized (ΔNNO=+7) fO2 is <1(ohm.m)-1, the sample being more conductive when reduced. The temperature dependence of σ was fitted using Arrhenian equations, the activation energy Ea being 100kJ/mol. Sodium was identified as the main charge carrier in the melts. The fO2-effect on σ can thus be attributed to the influence of the Fe2+/Fe3+ ratio on sodium mobility. The fO2-dependence of σ was included in the model of Pommier et al.(2008), allowing the conductivity of natural melts to be calculated as a function of T, P, H2O, and fO2. Variable fO2 experiments confirmed the increase in σ when reducing the melt. At 1200°C, for both reduction-oxidation cycles, a stable value of σ following a change in fO2 is reached in 15hours, while 2hours are needed at 1400°C. The real-time changes in σ of basaltic melts following fO2 step changes were monitored. The time-dependent changes in σ are interpreted in terms of kinetics processes due to redox reequilibration between melt and gas. The evolution of σ with time can be fitted using a diffusion-limited process for reduction in CO-CO2 gas mixtures and oxidation in air. However, a reaction at the gas-melt interface probably rate limits oxidation in CO2. Reduction and oxidation rates are similar and increase with T. Oxidation-reduction rates calculated from the analysis of the conductivity evolution with time range from 10-9 to 10-8m2/s for the T range 1200-1400°C. These reaction rates are in agreement with typical alkali diffusion coefficients in basaltic melts. However, the high value of Ea (230kJ/mol) calculated from the T dependence of the oxidation-reduction rates agrees with the Ea for alkali-Earth elements. Furthermore, microprobe analyses document the existence of alkali-Earth cation fluxes during oxidations and reductions. Such cation migration probably occurs to charge-balance electron fluxes in the melt, in agreement with the study of Cooper et al. (1996). Our results suggest that the migration of alkali and alkali-Earth elements rate-limits the redox state changes in basaltic melts, and that redox mechanisms are not restricted to oxygen chemical diffusion. A discussion of chemical vs tracer oxygen diffusion studies is proposed.

Chelyabinsk meteorite explains unusual spectral properties of Baptistina Asteroid Family

NASA Astrophysics Data System (ADS)

Reddy, Vishnu; Sanchez, Juan A.; Bottke, William F.; Cloutis, Edward A.; Izawa, Matthew R. M.; O'Brien, David P.; Mann, Paul; Cuddy, Matthew; Le Corre, Lucille; Gaffey, Michael J.; Fujihara, Gary

2014-07-01

We investigated the spectral and compositional properties of Chelyabinsk meteorite to identify its possible parent body in the main asteroid belt. Our analysis shows that the meteorite contains two spectrally distinct but compositionally indistinguishable components of LL5 chondrite and shock blackened/impact melt material. Our X-ray diffraction analysis confirms that the two lithologies of the Chelyabinsk meteorite are extremely similar in modal mineralogy. The meteorite is compositionally similar to LL chondrite and its most probable parent asteroid in the main belt is a member of the Flora family. Our work confirms previous studies (e.g., Vernazza et al. [2008]. Nature 454, 858-860; de León, J., Licandro, J., Serra-Ricart, M., Pinilla-Alonso, N., Campins, H. [2010]. Astron. Astrophys. 517, A23; Dunn, T.L., Burbine, T.H., Bottke, W.F., Clark, J.P. [2013]. Icarus 222, 273-282), linking LL chondrites to the Flora family. Intimate mixture of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides a spectral match with (8) Flora, the largest asteroid in the Flora family. The Baptistina family and Flora family overlap each other in dynamical space. Mineralogical analysis of (298) Baptistina and 11 small family members shows that their surface compositions are similar to LL chondrites, although their absorption bands are subdued and albedos lower when compared to typical S-type asteroids. A range of intimate mixtures of LL5 chondrite and shock blackened/impact melt material from Chelyabinsk provides spectral matches for all these BAF members. We suggest that the presence of a significant shock/impact melt component in the surface regolith of BAF members could be the cause of lower albedo and subdued absorption bands. The conceptual problem with part of this scenario is that impact melts are very rare within ordinary chondrites. Of the ∼42,000 ordinary chondrites, less than 0.5% (203) of them contain impact melts. A major reason that impact melts are rare in meteorites is that high impact velocities (V > 10 km/s) are needed to generate the necessary shock pressures and temperatures (e.g., Pierazzo, E., Melosh, H.J. [1998]. Hydrocode modeling of oblique impacts: The fate of the projectile. In: Origin of the Earth and Moon, Proceedings of the Conference. LPI Contribution No. 957) unless the target material is highly porous. Nearly all asteroid impacts within the main belt are at ∼5 km/s (Bottke, W.F., Nolan, M.C., Greenberg, R., Kolvoord, R.A. [1994]. Collisional lifetimes and impact statistics of near-Earth asteroids. In: Tucson, Gehrels T. (Ed.), Hazards Due to Comets and Asteroids. The University of Arizona Press, Arizona, pp. 337-357), which prevents them from producing much impact melt unless they are highly porous. However, shock darkening is an equally efficient process that takes place at much lower impact velocities (∼2 km/s) and can cause the observed spectral effects. Spectral effects of shock darkening and impact melt are identical. The parent asteroid of BAF was either a member of the Flora family or had the same basic composition as the Floras (LL Chondrite). The shock pressures produced during the impact event generated enough impact melt or shock blackening to alter the spectral properties of BAF, but keep the BAF composition largely unchanged. Collisional mixing of shock blackened/impact melt and LL5 chondritic material could have created the Baptistina Asteroid Family with composition identical to those of the Floras, but with subdued absorption bands. Shock darkening and impact melt play an important role in altering the spectral and albedo properties of ordinary chondrites and our work confirms earlier work by Britt and Pieters (Britt, D.T., Pieters, C.M. [1994]. Geochimica et Cosmochimica Acta 58, 3905-3919).

Oxidation and evaporation of sulfur species at atmospheric entry of iron sulfide fine particles

NASA Astrophysics Data System (ADS)

Isobe, H.; Murozono, K.

2017-12-01

Micrometeorites have the most abundant flux in current accumulation of planetary materials to the Earth. Micrometeorites are heated and reacted with upper atmosphere at atmospheric entry. Evaporation of meteoritic materials, especially sulfur species, may have environmental effect at upper atmosphere (e.g. Court and Sephton, 2011; Tomkins et al., 2016). Troilite is typical FeS phase in chondritic meteorites. In this study, quick heating and cooling experiments of FeS reagent particles were carried out with a fine particles free falling apparatus with controlled gas flow (Isobe and Gondo, 2013). Starting material reagent is inhomogeneous mixture of troilite, iron oxide and iron metal. Oxygen fugacity was controlled to FMQ +1.5 log unit. Maximum temperature of the particles was higher than 1400°C for approximately 0.5 seconds. Run products with rounded shape and smooth surface show the particles were completely melted. Chemical compositions of particles analyzed on cross sections are generally well homogenized from inhomogeneous starting materials by complete melting. Molar ratios of Fe in melted regions are close to 0.5, while compositions of S and O are various. Varieties of S and O compositions show various degree of oxidation and evaporation of sulfur. Distribution of compositions of melted regions in Fe-S-O system is plotted in liquidus compositions of FeO and FeS saturated melt. Troilite in micrometeorite is melted and oxidized by atmospheric entry. Compositions of FeS melt in fine spherules are following Fe-S-O phase relations even in a few seconds. Molar ratios of Fe in melt are close to 0.5, while compositions of S and O are various. Varieties of S and O compositions show various degree of oxidation and evaporation of sulfur. Evaporation of sulfur from meteoritic materials in atmospheric entry heating may depend on oxygen fugacity of the upper atmosphere. Sulfur supply from meteoritic materials to atmosphere may be limited on planets with oxygen-free atmosphere.

Experimental calibration of vanadium partitioning and stable isotope fractionation between hydrous granitic melt and magnetite at 800 °C and 0.5 GPa

NASA Astrophysics Data System (ADS)

Sossi, Paolo A.; Prytulak, Julie; O'Neill, Hugh St. C.

2018-04-01

Vanadium has multiple oxidation states in silicate melts and minerals, a property that also promotes fractionation of its isotopes. As a result, vanadium isotopes vary during magmatic differentiation, and can be powerful indicators of redox processes at high temperatures if their partitioning behaviour can be determined. To quantify the partitioning and isotope fractionation factor of V between magnetite and melt, piston cylinder experiments were performed in which magnetite and a hydrous, haplogranitic melt were equilibrated at 800 °C and 0.5 GPa over a range of oxygen fugacities ({f_{{{O}2}}}), bracketing those of terrestrial magmas. Magnetite is isotopically light with respect to the coexisting melt, a tendency ascribed to the VI-fold V3+ and V4+ in magnetite, and a mixture of IV- and VI-fold V5+ and V4+ in the melt. The magnitude of the fractionation factor systematically increases with increasing log{f_{{{O}2}}} relative to the Fayalite-Magnetite-Quartz buffer (FMQ), from Δ51Vmag-gl = - 0.63 ± 0.09‰ at FMQ - 1 to - 0.92 ± 0.11‰ (SD) at ≈ FMQ + 5, reflecting constant V3+/V4+ in magnetite but increasing V5+/V4+ in the melt with increasing log{f_{{{O}2}}}. These first mineral-melt measurements of V isotope fractionation factors underline the importance of both oxidation state and co-ordination environment in controlling isotopic fractionation. The fractionation factors determined experimentally are in excellent agreement with those needed to explain natural isotope variations in magmatic suites. Furthermore, these experiments provide a useful framework in which to interpret vanadium isotope variations in natural rocks and magnetites, and may be used as a potential fingerprint the redox state of the magma from which they crystallise.

U-Pb isotopic systematics of shock-loaded and annealed baddeleyite: Implications for crystallization ages of Martian meteorite shergottites

NASA Astrophysics Data System (ADS)

Niihara, Takafumi; Kaiden, Hiroshi; Misawa, Keiji; Sekine, Toshimori; Mikouchi, Takashi

2012-08-01

Shock-recovery and annealing experiments on basalt-baddeleyite mixtures were undertaken to evaluate shock effects on U-Pb isotopic systematics of baddeleyite. Shock pressures up to 57 GPa caused fracturing of constituent phases, mosaicism of olivine, maskelynitization of plagioclase, and melting, but the phase transition from monoclinic baddeleyite structure to high-pressure/temperature polymorphs of ZrO2 was not confirmed. The U-Pb isotopic systems of the shock-loaded baddeleyite did not show a large-scale isotopic disturbance. The samples shock-recovered from 47 GPa were then employed for annealing experiments at 1000 or 1300 °C, indicating that the basalt-baddeleyite mixture was almost totally melted except olivine and baddeleyite. Fine-grained euhedral zircon crystallized from the melt was observed around the relict baddeleyite in the sample annealed at 1300 °C for 1 h. The U-Pb isotopic systems of baddeleyite showed isotopic disturbances: many data points for the samples annealed at 1000 °C plotted above the concordia. Both radiogenic lead loss/uranium gain and radiogenic lead gain/uranium loss were observed in the baddeleyite annealed at 1300 °C. Complete radiogenic lead loss due to shock metamorphism and subsequent annealing was not observed in the shock-loaded/annealed baddeleyites studied here. These results confirm that the U-Pb isotopic systematics of baddeleyite are durable for shock metamorphism. Since shergottites still preserve Fe-Mg and/or Ca zonings in major constituent phases (i.e. pyroxene and olivine), the shock effects observed in Martian baddeleyites seem to be less intense compared to that under the present experimental conditions. An implication is that the U-Pb systems of baddeleyite in shergottites will provide crystallization ages of Martian magmatic rocks.

Compared production behavior of borax and unborax premixed SiC reinforcement Al7Si-Mg-TiB alloys composites with semi-solid stir casting method

NASA Astrophysics Data System (ADS)

Haryono, M. B.; Sulardjaka, Nugroho, Sri

2016-04-01

The present study was aimed to investigate the effect of borax additive on physical and mechanical properties of Al7Si-Mg-TiB with the reinforcement of silicon carbide. In this case, the different weight percentage from the reinforcement of SiC (10, 15, and 20% wt), and the borax additive (ratio 1:4) were homogenously added into the matrix by employing the semi-solid stir casting method at the temperature of 590°C. Al7Si-Mg-TiB melted in an electric resistance furnace at 800°C for 25 minutes and the holding time of 5 minutes; SiC was stirred with borax inside the chamber and heated at the temperature of 250°C for 25 minutes. Then, it melted by lowing the temperature into 590°C. The SiC-borax mixture was added into the electric resistance furnace, and automatically stirred by the stirrer at a constant speed (500 rpm for 3 minutes) in the composite A17Si-Mg-TiB. It melted when heated at 750°C for 17minutes,then, casting was performed on the prepared mould. The characterizations of Al7Si-Mg-TiB-SiC/borax were porosity, hardness, and microstructure on the Al7Si-Mg-TiB-SiC/ borax. The porosity of AMC tended to increase along with the increaseof the wt% SiC (1.4%-3.6%); however, borax additive underwent a decrease in porosity (0.14%-1.3%). Further, hardness tended to improve along with the increase of wt% SiC. The unboraxmixture had 79,6 HRB up to 94 HRB. Whereas, the borax additive mixture had 105,8 HRB up to 121 HRB.

The morphology of blends of linear and branched polyethylenes by small-angle neutron and x-ray scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Londono, J.D.; Wignall, G.D.; Lin, J.S.

1995-12-31

The solid-state morphology and liquid-state homogeneity of blends of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) were investigated by small-angle neutron and x-ray scattering (SANS and SAXS). The solid state morphology was investigated as a function of composition and cooling rate from the melt. After slow cooling, the evidence indicated that the mixtures were either completely (HDPE-rich blends) or almost completely (LDPE-rich blends) phase separated into separate HDPE and LDPE lamellae over the whole compositional range. In contrast, for rapidly quenched blends the components are extensively co-crystallized for all concentrations, though the SANS data indicated that the branched component hadmore » a tendency to be preferentially located in the inter-lamellar regions. In the liquid state, the blends were homogeneous at all compositions, showing that the solid state morphology is not determined by the melt structure, but is a function of the crystallization kinetics. Further evidence for blend homogeneity in the liquid is presented. In particular the authors examine the hypothesis that a phase separated mixture might give a scattering pattern similar to a homogeneous blend if the domain sizes were larger than the maximum spatial resolution of the SANS experiment (D > 2{pi}/Q{sub min} {approximately} 2,000 {angstrom}). In this scenario, the differential scattering cross section d{Sigma}/d{Omega}(Q) {approximately} Q{sup {minus}2}, though phase separation decreases the cross section in this Q-range with respect to the homogeneous blend. For HDPE/LDPE blends in the melt, this decrease in intensity was not observed, thus ruling out the possibility of phase separation.« less

Can Suspended Iron-Alloy Droplets Explain the Origin, Composition and Properties of Large Low Shear Velocity Provinces?

NASA Astrophysics Data System (ADS)

Zhang, Z.; Dorfman, S. M.; Labidi, J.; Zhang, S.; Manga, M.; Stixrude, L. P.; McDonough, W. F.; Williams, Q. C.

2014-12-01

The enigmatic large low shear velocity provinces (LLSVPs) identified by seismic tomography at the base of the Earth's mantle have been proposed to be reservoirs of primordial mantle composition tapped by hot spot volcanism. The LLSVPs are characterized by anomalously low shear wave speed, VS, slightly elevated bulk sound speed, VB, and high density, ρ, in piles as thick as 1000 km above the core-mantle boundary. This combination of properties could be explained by a few percent dense melt, but the solidus of the lower mantle silicate and oxide assemblage may be too high to produce melt over the large extent of these regions. Iron-rich sulfur-bearing alloy may be molten at the conditions of the LLSVPs and ~1-2% of this component could satisfy both constraints on VS and ρ. An Fe alloy phase in the LLSVPs also has the potential to explain geochemical anomalies associated with hot spot volcanism, and its existence can be constrained by geochemical mass balance. Primordial noble gases such as 3He would be preferentially dissolved in Fe-rich melt rather than crystalline silicates. The reconstructed abundances of the moderately siderophile/chalcophile elements S, Cu and Pb in iron-alloy-bearing LLSVPs do not exceed predicted losses from volatilization, though this depends on the S-content of the alloy. The alloy phase would also be expected to incorporate W, and W isotope anomalies associated with hot spots are thus expected to have important implications for the timing of LLSVP formation. We have developed a model, via CIDER-2014, for the origin and properties of LLSVPs incorporating geochemistry, mineral physics, and fluid dynamic constraints on the generation, capture, and thermoelastic properties of Fe-rich melt droplets. The solidification of a basal magma ocean would produce both solid silicates and metallic melt. The bulk of the alloy generated by this process would sink to merge with the core. However, once the density of the remnant liquid exceeds that of the solid, newly-formed crystals floating at the crystallization front may trap droplets of Fe-rich melt as inclusions or at grain boundaries. We find that a mixture of mantle silicates and ~1-2% molten Fe-rich droplets matches constraints on density and seismic velocities and could host the hidden 3He and other elements of the primordial mantle reservoir.

Room Temperature Curing Polymers

DTIC Science & Technology

1977-05-01

diglycidyl esters are low melting solids, they are easily purified by recrystallization . Both diglycidyl adipate and sebacate were prepared in 88...aromatic amine Shell Z (a eutectic mixture of methylene dianiline and m-phenylene- diamine). The Shell Z cured resins had apparent Tg’s near...cooled to 0oC. The white crystals which formed were recrystallized three times from methanol-water (9:1) to yield 248 g (88%) EEW = 125 (Theory 115

An Undergraduate Experiment Using Differential Scanning Calorimetry: A Study of the Thermal Properties of a Binary Eutectic Alloy of Tin and Lead

ERIC Educational Resources Information Center

D'Amelia, Ronald P.; Clark, Daniel; Nirode, William

2012-01-01

An alloy is an intimate association of two or more metals, with or without a definite composition, which has metallic properties. Heterogeneous alloys, such as tin-lead (Sn/Pb) solders, consist of a mixture of crystalline phases with different compositions. A homogeneous alloy with a unique composition having the lowest possible melting point is…

Removal of nanoaerosol during the bubbling of the salt melt of beryllium and lithium fluorides for the preparation of reactor radioisotopes

NASA Astrophysics Data System (ADS)

Zagnit'ko, A. V.; Chuvilin, D. Yu.

2010-06-01

The parameters of aerosol particles formed in the course of the spontaneous thermal condensation of vapors and bubbling a 66LiF-34BeF2 (mol %) eutectic salt mixture with helium have been studied. For this purpose, a vertical bubbling mode at T ≈ 900 K and an ampule device for obtaining reactor radioisotopes for medical applications were used. The rate of the bulk removal and the chemical composition of aerosols were measured. The size distribution of the aerosol particles was bimodal, and the mass concentration of the particles exceeded by far the maximum permissible concentration (MPC). The characteristics of regenerated nickel multilayer nanofilters for ultrahigh filtration of aerosols from the salt liquid melt were analyzed.

Low resistance electrode construction

DOEpatents

Redey, Laszlo; Karell, Eric J.

2002-01-01

An electrochemical cell having a cathode and an anode in contact with an electrolyte. Both electrodes or one of them has an electrically conducting non-metal receptacle defining a chamber with a first metal having a melting point in the range of from about room temperature to about 800.degree. C. inside said receptacle chamber. A second metal with a melting point greater than about 800.degree. C. is in contact with the first metal inside the receptacle chamber and extends outside of the receptacle chamber to form a terminal for the anode. The electrolyte may include the oxides, halides or mixtures thereof of one or more of Li, V, U, Al and the lanthanides. Metal may be produced at the cathode during operation of the cell and oxygen or chlorine at the anode.

Identification of non-volatile compounds and their migration from hot melt adhesives used in food packaging materials characterized by ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry.

PubMed

Vera, Paula; Canellas, Elena; Nerín, Cristina

2013-05-01

The identification of unknown non-volatile migrant compounds from adhesives used in food contact materials is a very challenging task because of the number of possible compounds involved, given that adhesives are complex mixtures of chemicals. The use of ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-MS/QTOF) is shown to be a successful tool for identifying non-targeted migrant compounds from two hot melt adhesives used in food packaging laminates. Out of the seven migrants identified and quantified, five were amides and one was a compound classified in Class II of the Cramer toxicity. None of the migration values exceeded the recommended Cramer exposure values.

Decarbonization process for carbothermically produced aluminum

DOEpatents

Bruno, Marshall J.; Carkin, Gerald E.; DeYoung, David H.; Dunlap, Sr., Ronald M.

2015-06-30

A method of recovering aluminum is provided. An alloy melt having Al.sub.4C.sub.3 and aluminum is provided. This mixture is cooled and then a sufficient amount of a finely dispersed gas is added to the alloy melt at a temperature of about 700.degree. C. to about 900.degree. C. The aluminum recovered is a decarbonized carbothermically produced aluminum where the step of adding a sufficient amount of the finely dispersed gas effects separation of the aluminum from the Al.sub.4C.sub.3 precipitates by flotation, resulting in two phases with the Al.sub.4C.sub.3 precipitates being the upper layer and the decarbonized aluminum being the lower layer. The aluminum is then recovered from the Al.sub.4C.sub.3 precipitates through decanting.

Characterization of physicochemical and thermal properties and crystallization behavior of krabok (Irvingia Malayana ) and rambutan seed fats.

PubMed

Sonwai, Sopark; Ponprachanuvut, Punnee

2012-01-01

Fatty acid composition, physicochemical and thermal properties and crystallization behavior of fats extracted from the seeds of krabok (Irvingia Malayana) and rambutan (Nephelium lappaceum L.) trees grown in Thailand were studied and compared with cocoa butter (CB). The krabok seed fat, KSF, consisted of 46.9% lauric and 40.3% myristic acids. It exhibited the highest saponification value and slip melting point but the lowest iodine values. The three fats displayed different crystallization behavior at 25°C. KSF crystallized into a mixture of β' and pseudo-β' structures with a one-step crystallization curve and high solid fat content (SFC). The fat showed simple DSC crystallization and melting thermograms with one distinct peak. The rambutan seed fat, RSF, consisted of 42.5% arachidic and 33.1% oleic acids. Its crystallization behavior was more similar to CB than KSF, displaying a two-step crystallization curve with SFC lower than that of KSF. RSF solidified into a mixture of β' and pseudo-β' before transforming to β after 24 h. The large spherulitic microstructures were observed in both KSF and RSF. According to these results, the Thai KSF and RSF exhibited physicochemical, thermal characteristics and crystallization behavior that could be suitable for specific applications in several areas of the food, cosmetic and pharmaceutical industries.

An experimental investigation of agglutinate melting mechanisms - Shocked mixtures of Apollo 11 and 16 soils

NASA Technical Reports Server (NTRS)

Simon, S. B.; Papike, J. J.; Horz, F.; See, T. H.

1986-01-01

Mixtures of chemically contrasting lunar soils have been shocked at pressures ranging from 18.2-62.0 GPa. Other than the generation of impact melts, modal and textural changes caused by shock include destruction of pore space and fused soil clasts and conversion of plagioclase to maskelynite. The loss of the fused soil component in these runs indicates that low agglutinate contents in shocked and/or compacted regolith breccias cannot be considered by themselves to be evidence of formation from immature regolith. From the petrographic and chemical data it appears that the impact glass formed mainly from the fine fraction and the fused soil component in the target, with relatively minor contributions from the other coarse clasts. The impact glasses exhibit the same chemical enrichments and depletions as their corresponding fine fractions and plot on or near a mixing line between the bulk and fine fraction of the soil in which they were formed. From this as well as several other studies it appears that the fusion of the finest fraction model is valid and that it accurately predicts the chemical systematics of impact glass formed from lunar soil. In addition, fusion of agglutinates present in the target soil is an important process.

The Effects of Polymer Carrier, Hot Melt Extrusion Process and Downstream Processing Parameters on the Moisture Sorption Properties of Amorphous Solid Dispersions

PubMed Central

Feng, Xin; Vo, Anh; Patil, Hemlata; Tiwari, Roshan V.; Alshetaili, Abdullah S.; Pimparade, Manjeet B.; Repka, Michael A.

2017-01-01

Objective The aim of this study was to evaluate the effect of polymer carrier, hot melt extrusion (HME) and downstream processing parameters on the water uptake properties of amorphous solid dispersions. Methods Three polymers and a model drug were used to prepare amorphous solid dispersions utilizing HME technology. The sorption-desorption isotherms of solid dispersions and their physical mixtures were measured by the Dynamic Vapor Sorption system, and the effect of polymer hydrophobicity, hygroscopicity, molecular weight and the HME process were investigated. FTIR imaging was performed to understand the phase separation driven by the moisture. Key findings Solid dispersions with polymeric carriers with lower hydrophilicity, hygroscopicity, and higher molecular weight could sorb less moisture under the high RH conditions. The water uptake ability of polymer-drug solid dispersion systems were decreased compared to the physical mixture after HME, which might be due to the decreased surface area and porosity. The FTIR imaging indicated the homogeneity of the drug molecularly dispersed within the polymer matrix was changed after exposure to high RH. Conclusion Understanding the effect of formulation and processing on the moisture sorption properties of solid dispersions is essential for the development of drug products with desired physical and chemical stability. PMID:26589107

High Temperature Chemistry in the Columbia Accident Investigation

NASA Technical Reports Server (NTRS)

Jacobson, Nathan; Opila, Elizabeth; Tallant, David; Simpson, Regina

2004-01-01

Initial estimates on the temperature and conditions of the breach in Columbia's wing focused on analyses of the slag deposits. These deposits are complex mixtures of the reinforced carbon/carbon (RCC) constituents, insulation material, and wing structural materials. However it was possible to clearly discern melted/solidified Cerachrome(R) insulation, indicating the temperatures had exceeded 1760 C. Current research focuses on the carbon/carbon in the path from the breach. Carbon morphology indicates heavy oxidation and erosion. Raman spectroscopy yielded further temperature estimates. A technique developed at Sandia National Laboratories is based on crystallite size in carbon chars. Lower temperatures yield nanocrystalline graphite; whereas higher temperatures yield larger graphite crystals. By comparison to standards the temperatures on the recovered RCC fragments were estimated to have been greater than 2700 C.

Experimentally determined sulfur isotope fractionation between metal and silicate and implications for planetary differentiation

NASA Astrophysics Data System (ADS)

Labidi, J.; Shahar, A.; Le Losq, C.; Hillgren, V. J.; Mysen, B. O.; Farquhar, J.

2016-02-01

The Earth's mantle displays a subchondritic 34S/32S ratio. Sulfur is a moderately siderophile element (i.e. iron-loving), and its partitioning into the Earth's core may have left such a distinctive isotope composition on the terrestrial mantle. In order to constrain the sulfur isotope fractionation occurring during core-mantle differentiation, high-pressure and temperature experiments were conducted with synthetic mixtures of metal and silicate melts. With the purpose to identify the mechanism(s) responsible for the S isotope fractionations, we performed our experiments in different capsules - namely, graphite and boron nitride capsules - and thus at different fO2, with varying major element chemistry of the silicate and metal fractions. The S isotope fractionations Δ34Smetal-silicate of equilibrated metal alloys versus silicate melts is +0.2 ± 0.1‰ in a boron-free and aluminum-poor system quenched at 1-1.5 GPa and 1650 °C. The isotope fractionation increases linearly with increasing boron and aluminum content, up to +1.4 ± 0.2‰, and is observed to be independent of the silicon abundance as well as of the fO2 over ∼3.5 log units of variations explored here. The isotope fractionations are also independent of the graphite or nitride saturation of the metal. Only the melt structural changes associated with aluminum and boron concentration in silicate melts have been observed to affect the strength of sulfur bonding. These results establish that the structure of silicate melts has a direct influence on the S2- average bonding strengths. These results can be interpreted in the context of planetary differentiation. Indeed, the structural environments of silicate evolve strongly with pressure. For example, the aluminum, iron or silicon coordination numbers increase under the effect of pressure. Consequently, based on our observations, the sulfur-bonding environment is likely to be affected. In this scheme, we tentatively hypothesize that S isotope fractionations between the silicate mantle and metallic core of terrestrial planetary bodies would depend on the average pressure at which their core-mantle differentiation occurred.

The Web-based Module of Changes in Objects

NASA Astrophysics Data System (ADS)

Triayomi, R.

2017-09-01

To understand the changes of substances contained in such a kind of substance and substance characteristics then need a deep study of the concept. In this concept is expected to understand the changes of objects such as substance type and substance characteristics. Types of substances and characteristics of substances through physical changes and chemical changes and means of separation consisting of two or more substances. The principle of separation of the mixture is based on differences in physical properties of its constituents, such as substances, particle size, melting point, boiling point, magnetic properties, solubility, and so forth. This study aims to produce a web-based module of changes in objects that are valid, practical, and have effectiveness of student learning outcomes and activities on natural science learning. The experiment was conducted on 30 children in South Sumatera. The case of the development of the learning module of change of the object is influenced by the child’s understanding of the concept. Expected to be adapted by world teachers.

Frozen yogurt with added inulin and isomalt.

PubMed

Isik, U; Boyacioglu, D; Capanoglu, E; Erdil, D Nilufer

2011-04-01

The objective of this study was to produce a frozen yogurt containing low fat and no added sugar. Samples containing 5% polydextrose, 0.065% aspartame and acesulfame-K mixture, and different levels of inulin and isomalt (5.0, 6.5, and 8.0%) were produced at pilot scale and analyzed for their physical and chemical properties including proximate composition, viscosity, acidity, overrun, melting rate, heat shock stability, as well as sensory characteristics, and viability of lactic acid bacteria. With the addition of inulin and isomalt, viscosity increased by 19 to 52% compared with that of sample B (reduced-fat control). The average calorie values of samples substituted with sweeteners were about 43% lower than that of original sample. Low-calorie frozen yogurt samples melted about 33 to 48% slower than the reduced-fat control sample at 45 min. Based on quantitative descriptive profile test results, statistically significant differences among products were observed for hardness, iciness, foamy melting, whey separation, and sweetness characteristics. The results of principal component analysis showed that the sensory properties of the sample containing 6.5% inulin and 6.5% isomalt were similar to those of control. Lactic acid bacteria counts of frozen yogurt were found to be between 8.12 and 8.49 log values, 3 mo after the production. The overall results showed that it is possible to produce an attractive frozen yogurt product with the incorporation of inulin and isomalt with no added sugar and reduced fat. Copyright © 2011 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Study of the preparation of Cu-TiC composites by reaction of soluble Ti and ball-milled carbon coating TiC

NASA Astrophysics Data System (ADS)

Xu, Xuexia; Li, Wenbin; Wang, Yong; Dong, Guozhen; Jing, Shangqian; Wang, Qing; Feng, Yanting; Fan, Xiaoliang; Ding, Haimin

2018-06-01

In this work, Cu-TiC composites have been successfully prepared by reaction of soluble Ti and carbon coating TiC. Firstly, the ball milling of graphite and TiC mixtures is used to obtain the carbon coating TiC which has fine size and improved reaction activity. After adding the ball milled carbon coating TiC into Cu-Ti melts, the soluble Ti will easily react with the carbon coating to form TiC. This process will also improve the wettability between Cu melts and TiC core. As a result, besides the TiC prepared by reaction of soluble Ti and carbon coating, the ball milled TiC will also be brought into the melts. Some of these ball-milled TiC particles will go on being coated by the formed TiC from the reaction of Ti and the coating carbon and left behind in the composites. However, most of TiC core will be further reacted with the excessive Ti and be transformed into the newly formed TiC with different stoichiometry. The results indicate that it is a feasible method to synthesize TiC in Cu melts by reaction of soluble Ti and ball-milled carbon coating TiC.

Physico-chemical characterization of nano-emulsions in cosmetic matrix enriched on omega-3.

PubMed

Kabri, Tin-Hinan; Arab-Tehrany, Elmira; Belhaj, Nabila; Linder, Michel

2011-09-21

Nano-emulsions, as non-equilibrium systems, present characteristics and properties which depend not only on composition but also on their method of preparation. To obtain better penetration, nanocosmeceuticals use nano-sized systems for the delivery of active ingredients to targeted cells. In this work, nano-emulsions composed of miglyol, rapeseed oil and salmon oil were developed as a cosmetic matrix. Measurements of different physico-chemical properties of nano-emulsions were taken according to size, electrophoretic mobility, conductivity, viscosity, turbidity, cristallization and melting point. The RHLB was calculated for each formulation in order to achieve maximum stability. Both tween 80 and soya lecithin were found to stabilize formulations. The results showed that rapeseed oil and miglyol are the predominant parameters for determining the expression of results concerning the characterization of emulsion. Based on the mixture design, we achieved the optimal point using the following formulation: 56.5% rapessed oil, 35.5% miglyol, and 8% salmon oil. We considered this formulation to be the best as a nanocosmeceutical product due to the small size, good turbidity, and average HLB. This study demonstrates the influence of formulation on the physico-chemical properties of each nano-emulsion obtained by the mixture design.

Mountains and Calderas on Io: Possible Implications for Lithosphere Structure and Magma Generation

USGS Publications Warehouse

Carr, M.H.; McEwen, A.S.; Howard, K.A.; Chuang, F.C.; Thomas, P.; Schuster, P.; Oberst, J.; Neukum, G.; Schubert, G.

1998-01-01

The combination of Voyager images and newly acquired Galileo images with low illumination and resolutions ranging from 2 to 6 km/pixel now allows determination of the global distribution of mountains and volcanic centers on Io. The mountains generally do not have characteristics typical of terrestrial volcanic landforms, they are evenly distributed across the surface and show no obvious correlation with known hot spots or plumes. Relative elevations, determined by shadow measurements and stereoscopy, indicate that mountains in the newly imaged area range in elevation up to at least 7.6 km. The origin of the mountains remains uncertain. Some appear to be multitiered volcanic constructs; others enclosing the partial remains of large circular depressions appear to be remnants of old volcanoes; yet others show extensive tectonic disruption. Volcanic centers also appear to be distributed evenly across the surface except for an apparently somewhat lower density at high latitudes. The low latitudes have one volcanic center per 7 ?? 104km2, and, on average, the centers are spaced roughly 250 km apart. The global distribution of high mountains suggests that the lithosphere over most of Io is thick. Although the thickness cannot be calculated, the previously suggested 30 km appears reasonable as a lower limit. The high rates of resurfacing combined with the likely dissipation of most of the tidal energy in the asthenosphere and underlying mantle implies a very low temperature gradient in the upper part of the lithosphere and steep gradients in the lower lithosphere. The slow rate of separation of melt from host rock in the magma source regions as a consequence of the low gravity on Io, coupled with the high rate of magma production, will likely result in larger melt fractions than is typical for source regions on Earth. The variety of volcanic landforms suggests that volcanic products with a range of compositions are deposited on the surface. This mixture will be carried downward through the lithosphere as a consequence of the 0.5-1.5 cm/yr resurfacing rates. During descent, the more volatile components will tend to be driven off early, but complete or near-complete melting at the base of the lithosphere may result in rehomogenization of the silicate mixture that remains. ?? 1998 Academic Press.

Physical-biopolymer characterization of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) blended with natural rubber latex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuntanoo, K., E-mail: thip-kk@hotmail.com; Promkotra, S., E-mail: sarunya@kku.ac.th; Kaewkannetra, P., E-mail: paknar@kku.ac.th

A biopolymer of polyhydroxybutyrate-co-hydroxyvalerate (PHBV) is blended with bio-based materials, natural rubber latex, to improve their microstructures. The various ratios between PHBV and natural rubber latex are examined to develop their mechanical properties. In general, physical properties of PHBV are hard, brittle and low flexible while natural rubber (NR) is presented itself as high elastic materials. Concentrations of the PHBV solution are constituted at 1%, 2% and 3% (w/v). The mixtures of their PHBV solutions to natural rubber latex are produced the blended films in three different ratios of 4:6, 5:5 and 6:4, respectively. They are characterized by appearance analysesmore » which are the scanning electron microscope (SEM), universal testing machine (UTM) and differential scanning calorimetry (DSC). The SEM photomicrographs of the blended films and the controlled PHBV can provide the void distribution in the range of 12-14% and 19-21%, respectively. For mechanical properties of the blended films, the various elastic moduli of 1%, 2% and 3% (w/v) PHBV are the average of 773, 956 and 1,007 kPa, respectively. The tensile strengths of the blends increase with the increased concentrations of PHBV, similarly trend to the elastic modulus. The crystallization and melting behavior of unmixed PHBV and the blends are determined by DSC. Melting transition temperatures (T{sub m}) of the unmixed PHBV are stated two melting peak at 154°C and 173°C. Besides, the melting peaks of the blends alter in the range of 152-156°C and 168-171°C, respectively. According to morphology of the blends, the void distribution decreases twice compared to the unmixed PHBV. The results of mechanical properties and thermal analysis indicate that the blended PHBV can be developed their properties by more resilient and wide range of temperature than usual.« less

Sediment-peridotite interactions in a thermal gradient: mineralogic and geochemical effects and the "sedimentary signature" of arc magmas

NASA Astrophysics Data System (ADS)

Woodland, Alan; Girnis, Andrei; Bulatov, Vadim; Brey, Gerhard; Höfer, Heidi; Gerdes, Axel

2017-04-01

Strong thermal and chemical gradients are characteristic of the slab-mantle interface in subduction zones where relatively cold sediments become juxtaposed with hotter peridotite of the mantle wedge. The formation of arc magmas is directly related to mass transfer processes under these conditions. We have undertaken a series of experiments to simulate interactions and mass transfer at the slab-mantle interface. In addition to having juxtaposed sediment and peridotite layers, the experiments were performed under different thermal gradients. The sediment had a composition similar to GLOSS (1) and also served as the source of H2O, CO2 and a large selection of trace elements. The peridotite was a depleted garnet harzburgite formed from a mixture of natural hand-picked olivine, opx and garnet. Graphite was added to this mixture to establish a redox gradient between the two layers. Experiments were performed at 7.5-10 GPa to simulate the processes during deep subduction. The thermal gradient was achieved by displacing the sample capsule (Re-lined Pt) from the center of the pressure cell. The gradient was monitored with separate thermocouples at each end of the capsule and by subsequent opx-garnet thermometry across the sample. Maximum temperatures varied from 1400˚ -900˚ C and gradients ranged from 200˚ -800˚ C. Thus, in some experiments melting occurred in the sediment layer and in others this layer remained subsolidus, only devolatilizing. Major and trace elements were transported both in the direction of melt percolation to the hot zone, as well as down temperature. This leads to the development of zones with discrete phase assemblages. Olivine in the peridotite layer becomes converted to orthopyroxene, which is due to Si addition, but also migration of Mg and Fe towards the sediment. In the coldest part of a sample, the sediment is converted into an eclogitic cpx + garnet assemblage. A thin zone depleted in almost all trace elements is formed in peridotite directly above the sediment/peridotite boundary and defines the region of maximum metasomatic alteration. With a low Tmin, fluid-mobile Ba, Rb, Sr and Li are more strongly transported into the melt zone compared to HFSE and REE. At Tmin > 700˚ C, all incompatible elements are extracted from the solid into the melt. However, the mineral assemblage controls which elements are held back in the solid residue (i.e. MREE, HREE, Y, Sc, and to a lesser extent Ti, Zr and Hf in garnet). Peridotite-sediment interaction can produce humite-group minerals, particularly in the presence of F. Negative Nb-Ta anomalies are caused by rutile and/or humite phases. Transport of melt or fluid from the sediment to the overlying mantle wedge produces metasomatized magma sources from which basaltic melts with sedimentary geochemical signatures can be derived. Adding even 1% of melt or fluid to depleted mantle peridotite is sufficient to produce basaltic melts with incompatible element contents similar to those observed in natural subduction-related magmas. Such signatures are retained at 6.5 and even 10 GPa when Tmin < 700˚ C. Plank, T., Langmuir C., 1998. Chem. Geol. 145, 325-394.

Oxidation kinetics of molten copper sulfide

NASA Astrophysics Data System (ADS)

Alyaser, A. H.; Brimacombe, J. K.

1995-02-01

The oxidation kinetics of molten Cu2S baths, during top lancing with oxygen/nitrogen (argon) mixtures, have been investigated as a function of oxygen partial pressure (0.2 to 0.78), bath temperature (1200 °C to 1300 °C), gas flow rate (1 to 4 L/min), and bath mixing. Surface-tension-driven flows (the Marangoni effect) were observed both visually and photographically. Thus, the oxidation of molten Cu2S was found to progress in two distinct stages, the kinetics of which are limited by the mass transfer of oxygen in the gas phase to the melt surface. During the primary stage, the melt is partially desulfurized while oxygen dissolves in the liquid sulfide. Upon saturation of the melt with oxygen, the secondary stage commences in which surface and bath reactions proceed to generate copper and SO2 electrochemically. A mathematical model of the reaction kinetics has been formulated and tested against the measurements. The results of this study shed light on the process kinetics of the copper blow in a Peirce-Smith converter or Mitsubishi reactor.

Green glass vitrophyre 78526 - An impact of very low-Ti mare basalt composition

NASA Technical Reports Server (NTRS)

Warner, R. D.; Taylor, G. J.; Kiel, K.; Planner, H. H.; Nehru, C. E.; Ma, M.-S.; Schmitt, R. A.

1978-01-01

Rake sample 78526 is an 8.77 g rock consisting primarily of vitrophyric pale green glass with subordinate mineral and lithic relics. Petrographic and compositional evidence leads to the following conclusions: (1) the bulk composition represents that of a mixture formed by impact melting of at least two different textural and compositional varieties of VLT mare basalt that are now present in the rock as lithic relics and a poorly defined low-Ti mare basalt component observed in thin section only in the form of isolated mineral relics; (2) the admixed VLT mare basalts had REE abundances lower than those found in other mare basalts (but probably higher than emerald green glass) and REE patterns showing significant enrichment of the heavy relative to light REE's, suggesting that they were derived by comparatively high degrees of partial melting of a clinopyroxene-rich source region; and (3) the impact melt supercooled to produce the vitrophyre, with rather sharply contrasting textural domains present in the vitrophyre resulting from differences in nucleation kinetics and degrees of supercooling in various portions of the sample.

Properties of hot-melt extruded theophylline tablets containing poly(vinyl acetate).

PubMed

Zhang, F; McGinity, J W

2000-09-01

The objectives of this study were to investigate the properties of poly(vinyl acetate) (PVAc) as a retardant polymer and to study the drug release mechanism of theophylline from matrix tablets prepared by hot-melt extrusion. A physical mixture of drug, polymer, and drug release modifiers was fed into the equipment and heated inside the barrel of the extruder. The cylindrical extrudates were either cut into tablets or ground into granules and compressed with other excipients into tablets. Due to the low glass transition temperature of the PVAc, the melt extrusion process was conducted at approximately 70 degrees C. Theophylline was used as the model drug in this study. Theophylline was present in the extrudate in its crystalline form and was released from the tablets by diffusion. The Higuchi diffusion model and percolation theories were applied to the dissolution data to explain the drug release properties of the matrix systems. The release rate was shown to be dependent on the granule size, drug particle size, and drug loading in the tablets. Water-soluble polymers were demonstrated to be efficient release rate modifiers for this system.

Shape-memory NiTi foams produced by replication of NaCl space-holders.

PubMed

Bansiddhi, A; Dunand, D C

2008-11-01

NiTi foams were created with a structure (32-36% open pores 70-400 microm in size) and mechanical properties (4-25 GPa stiffness, >1000 MPa compressive strength, >42% compressive ductility, and shape-memory strains up to 4%) useful for bone implant applications. A mixture of NiTi and NaCl powders was hot-isostatically pressed at 950 and 1065 degrees C and the NaCl phase was then dissolved in water. The resulting NiTi foams show interconnected pores that replicate the shape and size of the NaCl powders, indicating that NiTi powders densified significantly before NaCl melted at 801 degrees C. Densifying NiTi or other metal powders above the melting point of the space-holder permits the use of NaCl, with the following advantages compared with higher-melting, solid space-holders such as oxides and fluorides used to date: (i) no temperature limit for densification; (ii) lower cost; (iii) greater flexibility in powder (and thus pore) shape; (iv) faster dissolution; (v) reduced metal corrosion during dissolution; (vi) lower toxicity if space-holder residues remain in the foam.

Better latent heat and specific heat of stearic acid with magnetite/graphene nanocomposite addition for thermal storage application

NASA Astrophysics Data System (ADS)

Andiarto, R.; Nuryadin, M. K.; Taufik, A.; Saleh, R.

2017-04-01

In our previous study, the addition of Magnetite (Fe3O4) into Stearic acid (Sa) as an organic phase change material (PCM) shows an enhancement in the latent heat for thermal energy storage applications. The latent heat of the PCM can also be increased by adding graphene material. Therefore, in this research, the thermal properties of Sa have been studied by the sonication method for several different concentrations of Fe3O4/Graphene nanocomposite additions. The structural properties of all of the samples were observed by X-Ray diffraction (XRD). Melting-solidifying behavior and specific heat value were measured by differential scanning calorimetry (DSC). The thermal degradation process of all samples was investigated by thermogravimetric analysis (TGA). Based on the DSC results, the presence of Fe3O4/Graphene in the Sa enhances the latent heat up to 20%. The specific heat value of the mixture was also found to be increased as the concentration of Fe3O4/Graphene to Sa increased. The TGA results show a lowered thermal degradation process of the Sa by the addition of the Fe3O4/Graphene which indicates a higher thermal stability of the mixture. In conclusion, the results demonstrate that the addition of Fe3O4/Graphene to Sa improves both the sensible heat and the latent heat of the mixture which are very important for thermal energy storage applications

Chemistry and Mechanism of Interaction Between Molybdenite Concentrate and Sodium Chloride When Heated in the Presence of Oxygen

NASA Astrophysics Data System (ADS)

Aleksandrov, P. V.; Medvedev, A. S.; Imideev, V. A.; Moskovskikh, D. O.

2017-04-01

Roasting of molybdenum concentrates with sodium chloride has high potential and can be an alternative to oxidizing roasting and autoclave leaching; however, the chemistry and mechanism are poorly known. The chemical mechanism of the roasting process between molybdenite concentrate and sodium chloride in the presence of atmospheric oxygen is proposed. It is demonstrated that the process occurs through molybdenite oxidation, up to molybdenum trioxide, with subsequent formation of sodium polymolybdates and molybdenum dioxydichloride from molybdenum trioxide. It is found that the formation of water-soluble sodium polymolybdates from molybdenum trioxide stops over time due to passivation of sodium chloride surface by polymolybdates. It is proved experimentally that preliminary grinding of the mixture in a furnace charge leads to an increase in the polymolybdate fraction of the roasting products, which constitutes approximately 65 pct of molybdenum initially in the roasted mixture against 20 to 22 pct in a nonground mixture (or 75 to 77 pct against 30 to 33 pct of molybdenum in calcine). For the first time, the presence of the Na2S2O7 phase in the calcine was confirmed experimentally. The suggested mechanism gives possible explanations for the sharp increase of MoO2Cl2 formation within the temperature range of 673 K to 723 K (400 °C to 450 °C) that is based on the catalytic reaction of molybdenum dioxydichloride from the Na2S2O7 liquid phase as it runs in a melt.

Osmium isotope and highly siderophile element systematics of lunar impact melt breccias: Implications for the late accretion history of the Moon and Earth

USGS Publications Warehouse

Puchtel, I.S.; Walker, R.J.; James, O.B.; Kring, D.A.

2008-01-01

To characterize the compositions of materials accreted to the Earth-Moon system between about 4.5 and 3.8 Ga, we have determined Os isotopic compositions and some highly siderophile element (HSE: Re, Os, Ir, Ru, Pt, and Pd) abundances in 48 subsamples of six lunar breccias. These are: Apollo 17 poikilitic melt breccias 72395 and 76215; Apollo 17 aphanitic melt breccias 73215 and 73255; Apollo 14 polymict breccia 14321; and lunar meteorite NWA482, a crystallized impact melt. Plots of Ir versus other HSE define excellent linear correlations, indicating that all data sets likely represent dominantly two-component mixtures of a low-HSE target, presumably endogenous component, and a high-HSE, presumably exogenous component. Linear regressions of these trends yield intercepts that are statistically indistinguishable from zero for all HSE, except for Ru and Pd in two samples. The slopes of the linear regressions are insensitive to target rock contributions of Ru and Pd of the magnitude observed; thus, the trendline slopes approximate the elemental ratios present in the impactor components contributed to these rocks. The 187Os/188Os and regression-derived elemental ratios for the Apollo 17 aphanitic melt breccias and the lunar meteorite indicate that the impactor components in these samples have close affinities to chondritic meteorites. The HSE in the Apollo 17 aphanitic melt breccias, however, might partially or entirely reflect the HSE characteristics of HSE-rich granulitic breccia clasts that were incorporated in the impact melt at the time of its creation. In this case, the HSE characteristics of these rocks may reflect those of an impactor that predated the impact event that led to the creation of the melt breccias. The impactor components in the Apollo 17 poikilitic melt breccias and in the Apollo 14 breccia have higher 187Os/188Os, Pt/Ir, and Ru/Ir and lower Os/Ir than most chondrites. These compositions suggest that the impactors they represent were chemically distinct from known chondrite types, and possibly represent a type of primitive material not currently delivered to Earth as meteorites. ?? 2008 Elsevier Ltd.

Temperature Dependence of Density, Viscosity and Electrical Conductivity for Hg-Based II-VI Semiconductor Melts

NASA Technical Reports Server (NTRS)

Li, C.; Ban, H.; Lin, B.; Scripa, R. N.; Su, C.-H.; Lehoczky, S. L.

2004-01-01

The relaxation phenomenon of semiconductor melts, or the change of melt structure with time, impacts the crystal growth process and the eventual quality of the crystal. The thermophysical properties of the melt are good indicators of such changes in melt structure. Also, thermophysical properties are essential to the accurate predication of the crystal growth process by computational modeling. Currently, the temperature dependent thermophysical property data for the Hg-based II-VI semiconductor melts are scarce. This paper reports the results on the temperature dependence of melt density, viscosity and electrical conductivity of Hg-based II-VI compounds. The melt density was measured using a pycnometric method, and the viscosity and electrical conductivity were measured by a transient torque method. Results were compared with available published data and showed good agreement. The implication of the structural changes at different temperature ranges was also studied and discussed.

Surface nitridation improves bone cell response to melt-derived bioactive silicate/borosilicate glass composite scaffolds.

PubMed

Orgaz, Felipe; Dzika, Alexandra; Szycht, Olga; Amat, Daniel; Barba, Flora; Becerra, José; Santos-Ruiz, Leonor

2016-01-01

Novel bioactive amorphous glass-glass composite scaffolds (ICIE16/BSG) with interconnected porosity have been developed. Hierarchically interconnected porous glass scaffolds were prepared from a mixture of two melt-derived glasses: a ICIE16 bioactive glass that was previously developed by Wu et al. (2011) to prevent crystallization, and a borosilicate glass of composition 73.48 SiO2-11.35 B2O3-15.15 Na2O (wt%). The resulting melt derived glass-glass composite scaffolds (ICIE16/BSG) were subject to surface functionalization to further improve its interaction with biological systems. Surface functionalization was performed by a nitridation process with hot gas N2/ammonia at 550°C for 2h, obtaining the ICIE16/BSG-NITRI. Evaluation of the degradation rate and the conversion to hydroxyapatite after immersion in simulated body fluid predicted a good biological activity of all the scaffolds, but particularly of the nitrided ones. In vitro evaluation of osteoblastic cells cultured onto the nitrided and non-nitrided scaffolds showed cell attachment, proliferation and differentiation on all scaffolds, but both proliferation and differentiation were improved in the nitrided ICIE16/BSG-NITRI. Biomaterials are often required in the clinic to stimulate bone repair. We have developed a novel bioglass (ICIE16/SBG-NITRI) that can be sintered into highly porous 3D scaffolds, and we have further improved its bioactivity by nitridation. ICIE16/SBG-NITRI was synthesized from a mixture of two melt-derived glasses through combined gel casting and foam replication techniques, followed by nitridation. To mimic bone, it presents high-interconnected porosity while being mechanically stable. Nitridation improved its reactivity and bioactivity facilitating its resorption and the deposition of apatite (bone-like mineral) on its surface and increasing its degradation rate. The nitrided surface also improved the bioglass' interaction with bone cells, which were found to attach better to ICIE16/SBG-NITRI and to differentiate earlier on its surface. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effects of process parameters on properties of porous foams formed by laser-assisted melting of steel powder (AISI P21)/foaming agent (ZrH2) mixture

NASA Astrophysics Data System (ADS)

Seo, Ja-Ye; Lee, Ki-Yong; Shim, Do-Sik

2018-01-01

This paper describes the fabrication of lightweight metal foams using the directed energy deposition (DED) method. DED is a highly flexible additive manufacturing process wherein a metal powder mixed with a foaming agent is sprayed while a high-power laser is used to simultaneously melt the powder mixture into layered metal foams. In this study, a mixture of a carbon steel material (P21 powder) and a widely used foaming agent, ZrH2, is used to fabricate metal foams. The effects of various process parameters, such as the laser power, powder feed rate, powder gas flow rate, and scanning speed, on the deposition characteristics (porosity, pore size, and pore distribution) are investigated. The synthesized metal foams exhibit porosities of 10% or lower, and a mean pore area of 7 × 105 μm2. It is observed that the degree of foaming increases in proportion to the laser power to a certain extent. The results also show that the powder feed rate has the most pronounced effect on the porosity of the metal foams, while the powder gas flow rate is the most suitable parameter for adjusting the size of the pores formed within the foams. Further, the scanning speed, which determines the amounts of energy and powder delivered, has a significant effect on the height of the deposits as well as on the properties of the foams. Thus, during the DED process for fabricating metal foams, the pore size and distribution and hence the foam porosity can be tailored by varying the individual process parameters. These findings should be useful as reference data for the design of processes for fabricating porous metallic materials that meet the specific requirements for specialized parts.

Technology of Strengthening Steel Details by Surfacing Composite Coatings

NASA Astrophysics Data System (ADS)

Burov, V. G.; Bataev, A. A.; Rakhimyanov, Kh M.; Mul, D. O.

2016-04-01

The article considers the problem of forming wear resistant meal ceramic coatings on steel surfaces using the results of our own investigations and the analysis of achievements made in the country and abroad. Increasing the wear resistance of surface layers of steel details is achieved by surfacing composite coatings with carbides or borides of metals as disperse particles in the strengthening phase. The use of surfacing on wearing machine details and mechanisms has a history of more than 100 years. But still engineering investigations in this field are being conducted up to now. The use of heating sources which provide a high density of power allows ensuring temperature and time conditions of surfacing under which composites with peculiar service and functional properties are formed. High concentration of energy in the zone of melt, which is created from powder mixtures and the hardened surface layer, allows producing the transition zone between the main material and surfaced coating. Surfacing by the electron beam directed from vacuum to the atmosphere is of considerable technological advantages. They give the possibility of strengthening surface layers of large-sized details by surfacing powder mixtures without their preliminary compacting. A modified layer of the main metal with ceramic particles distributed in it is created as a result of heating surfaced powders and the detail surface layer by the electron beam. Technology of surfacing allows using powders of refractory metals and graphite in the composition of powder mixtures. They interact with one another and form the particles of the hardening phase of the composition coating. The chemical composition of the main and surfaced materials is considered to be the main factor which determines the character of metallurgical processes in local zones of melt as well as the structure and properties of surfaced composition.

Modelling the effect of mixture components on permeation through skin.

PubMed

Ghafourian, T; Samaras, E G; Brooks, J D; Riviere, J E

2010-10-15

A vehicle influences the concentration of penetrant within the membrane, affecting its diffusivity in the skin and rate of transport. Despite the huge amount of effort made for the understanding and modelling of the skin absorption of chemicals, a reliable estimation of the skin penetration potential from formulations remains a challenging objective. In this investigation, quantitative structure-activity relationship (QSAR) was employed to relate the skin permeation of compounds to the chemical properties of the mixture ingredients and the molecular structures of the penetrants. The skin permeability dataset consisted of permeability coefficients of 12 different penetrants each blended in 24 different solvent mixtures measured from finite-dose diffusion cell studies using porcine skin. Stepwise regression analysis resulted in a QSAR employing two penetrant descriptors and one solvent property. The penetrant descriptors were octanol/water partition coefficient, logP and the ninth order path molecular connectivity index, and the solvent property was the difference between boiling and melting points. The negative relationship between skin permeability coefficient and logP was attributed to the fact that most of the drugs in this particular dataset are extremely lipophilic in comparison with the compounds in the common skin permeability datasets used in QSAR. The findings show that compounds formulated in vehicles with small boiling and melting point gaps will be expected to have higher permeation through skin. The QSAR was validated internally, using a leave-many-out procedure, giving a mean absolute error of 0.396. The chemical space of the dataset was compared with that of the known skin permeability datasets and gaps were identified for future skin permeability measurements. Copyright 2010 Elsevier B.V. All rights reserved.

Molecular dynamics simulation of a needle-sphere binary mixture

NASA Astrophysics Data System (ADS)

Raghavan, Karthik

This paper investigates the dynamic behaviour of a hard needle-sphere binary system using a novel numerical technique called the Newton homotopy continuation (NHC) method. This mixture is representative of a polymer melt where both long chain molecules and monomers coexist. Since the intermolecular forces are generated from hard body interactions, the consequence of missed collisions or incorrect collision sequences have a significant bearing on the dynamic properties of the fluid. To overcome this problem, in earlier work NHC was chosen over traditional Newton-Raphson methods to solve the hard body dynamics of a needle fluid in random media composed of overlapping spheres. Furthermore, the simplicity of interactions and dynamics allows us to focus our research directly on the effects of particle shape and density on the transport behaviour of the mixture. These studies are also compared with earlier works that examined molecular chains in porous media primarily to understand the differences in molecular transport in the bulk versus porous systems.

Boussinesq approximation of the Cahn-Hilliard-Navier-Stokes equations.

PubMed

Vorobev, Anatoliy

2010-11-01

We use the Cahn-Hilliard approach to model the slow dissolution dynamics of binary mixtures. An important peculiarity of the Cahn-Hilliard-Navier-Stokes equations is the necessity to use the full continuity equation even for a binary mixture of two incompressible liquids due to dependence of mixture density on concentration. The quasicompressibility of the governing equations brings a short time-scale (quasiacoustic) process that may not affect the slow dynamics but may significantly complicate the numerical treatment. Using the multiple-scale method we separate the physical processes occurring on different time scales and, ultimately, derive the equations with the filtered-out quasiacoustics. The derived equations represent the Boussinesq approximation of the Cahn-Hilliard-Navier-Stokes equations. This approximation can be further employed as a universal theoretical model for an analysis of slow thermodynamic and hydrodynamic evolution of the multiphase systems with strongly evolving and diffusing interfacial boundaries, i.e., for the processes involving dissolution/nucleation, evaporation/condensation, solidification/melting, polymerization, etc.

Advances in Glass Formulations for Hanford High-Aluminum, High-Iron and Enhanced Sulphate Management in HLW Streams - 13000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruger, Albert A.

2013-07-01

The current estimates and glass formulation efforts have been conservative in terms of achievable waste loadings. These formulations have been specified to ensure that the glasses are homogenous, contain essentially no crystalline phases, are processable in joule-heated, ceramic-lined melters and meet Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract terms. The WTP's overall mission will require the immobilization of tank waste compositions that are dominated by mixtures of aluminum (Al), chromium (Cr), bismuth (Bi), iron (Fe), phosphorous (P), zirconium (Zr), and sulphur (S) compounds as waste-limiting components. Glass compositions for these waste mixtures have been developed based upon previousmore » experience and current glass property models. Recently, DOE has initiated a testing program to develop and characterize HLW glasses with higher waste loadings and higher throughput efficiencies. Results of this work have demonstrated the feasibility of increases in waste loading from about 25 wt% to 33-50 wt% (based on oxide loading) in the glass depending on the waste stream. In view of the importance of aluminum limited waste streams at Hanford (and also Savannah River), the ability to achieve high waste loadings without adversely impacting melt rates has the potential for enormous cost savings from reductions in canister count and the potential for schedule acceleration. Consequently, the potential return on the investment made in the development of these enhancements is extremely favorable. Glass composition development for one of the latest Hanford HLW projected compositions with sulphate concentrations high enough to limit waste loading have been successfully tested and show tolerance for previously unreported tolerance for sulphate. Though a significant increase in waste loading for high-iron wastes has been achieved, the magnitude of the increase is not as substantial as those achieved for high-aluminum, high-chromium, high-bismuth or sulphur. Waste processing rate increases for high-iron streams as a combined effect of higher waste loadings and higher melt rates resulting from new formulations have been achieved. (author)« less

Advances in Glass Formulations for Hanford High-Alumimum, High-Iron and Enhanced Sulphate Management in HLW Streams - 13000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruger, Albert A.

2013-01-16

The current estimates and glass formulation efforts have been conservative in terms of achievable waste loadings. These formulations have been specified to ensure that the glasses are homogenous, contain essentially no crystalline phases, are processable in joule-heated, ceramic-lined melters and meet Hanford Tank Waste Treatment and Immobilization Plant (WTP) Contract terms. The WTP?s overall mission will require the immobilization of tank waste compositions that are dominated by mixtures of aluminum (Al), chromium (Cr), bismuth (Bi), iron (Fe), phosphorous (P), zirconium (Zr), and sulphur (S) compounds as waste-limiting components. Glass compositions for these waste mixtures have been developed based upon previousmore » experience and current glass property models. Recently, DOE has initiated a testing program to develop and characterize HLW glasses with higher waste loadings and higher throughput efficiencies. Results of this work have demonstrated the feasibility of increases in waste loading from about 25 wt% to 33-50 wt% (based on oxide loading) in the glass depending on the waste stream. In view of the importance of aluminum limited waste streams at Hanford (and also Savannah River), the ability to achieve high waste loadings without adversely impacting melt rates has the potential for enormous cost savings from reductions in canister count and the potential for schedule acceleration. Consequently, the potential return on the investment made in the development of these enhancements is extremely favorable. Glass composition development for one of the latest Hanford HLW projected compositions with sulphate concentrations high enough to limit waste loading have been successfully tested and show tolerance for previously unreported tolerance for sulphate. Though a significant increase in waste loading for high-iron wastes has been achieved, the magnitude of the increase is not as substantial as those achieved for high-aluminum, high-chromium, high-bismuth or sulphur. Waste processing rate increases for high-iron streams as a combined effect of higher waste loadings and higher melt rates resulting from new formulations have been achieved.« less

Crosslinking of Perfluorocarbon Polymers

DTIC Science & Technology

1977-04-01

absorption in the 8.0-8.7 M region, the presence of oxide can be excluded and thus the higher than to date reported melting point is most likely due...did not produce any epoxide. Apparently the stabilizer present in the Mallinckrodt hydrogen peroxide ( acetanilide ) promoted degradation of the epoxide...DTA curve (see Figure 3) Freon E-7 has a boiling point above 2500C. The broadness of the endotherm indicates that it is a multi-component mixture

Spontaneous, Metal-Catalyzed, and Enzyme-Catalyzed Decarboxylation of Oxalosuccinic Acid.

DTIC Science & Technology

1980-01-01

acid, 2,4- dinitrophenylhydrazine was added. This yielded a hydrazone which, after two recrystallizations, melted at 2200C. A sample of the a...accurately determined to be 24,500 at a wavelength of 352 nm (46). 34 2,4- Dinitrophenylhydrazine . Obtained from the Eastman Kodak Chemicals Division...reaction with 2,4- dinitrophenylhydrazine (57). The reaction mixture was sampled hourly during the daytime for a period of three days. The concentration of a

Followup to Columbia Investigation: Reinforced Carbon/Carbon From the Breach Location in the Wing Leading Edge Studied

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Opila, Elizabeth J.; Tallant, David

2005-01-01

Initial estimates on the temperature and conditions of the breach in the Space Shuttle Columbia's wing focused on analyses of the slag deposits. These deposits are complex mixtures of the reinforced carbon/carbon (RCC) constituents, insulation material, and wing structural materials. Identification of melted/solidified Cerachrome insulation (Thermal Ceramics, Inc., Augusta, GA) indicated that the temperatures at the breach had exceeded 1760 C.

Thermal model for impact breccia lithification - Manicouagan and the moon

NASA Technical Reports Server (NTRS)

Simonds, C. H.; Warner, J. L.; Phinney, W. C.; Mcgee, P. E.

1976-01-01

The thermal model of Simonds (1975) is extended to the full spectrum of impact-produced rocks ranging from fragmental breccias to impact melts, with reference to the Manicouagan impact structure in Quebec. This is done by relating the basic textural features of impact-lithified rocks to variations in the mixture of superheated impact-fused material originating near the point of impact and much cooler fragmented debris originating farther from the point of impact.

A unified momentum equation approach for computing thermal residual stresses during melting and solidification

NASA Astrophysics Data System (ADS)

Yeo, Haram; Ki, Hyungson

2018-03-01

In this article, we present a novel numerical method for computing thermal residual stresses from a viewpoint of fluid-structure interaction (FSI). In a thermal processing of a material, residual stresses are developed as the material undergoes melting and solidification, and liquid, solid, and a mixture of liquid and solid (or mushy state) coexist and interact with each other during the process. In order to accurately account for the stress development during phase changes, we derived a unified momentum equation from the momentum equations of incompressible fluids and elastoplastic solids. In this approach, the whole fluid-structure system is treated as a single continuum, and the interaction between fluid and solid phases across the mushy zone is naturally taken into account in a monolithic way. For thermal analysis, an enthalpy-based method was employed. As a numerical example, a two-dimensional laser heating problem was considered, where a carbon steel sheet was heated by a Gaussian laser beam. Momentum and energy equations were discretized on a uniform Cartesian grid in a finite volume framework, and temperature-dependent material properties were used. The austenite-martensite phase transformation of carbon steel was also considered. In this study, the effects of solid strains, fluid flow, mushy zone size, and laser heating time on residual stress formation were investigated.

A Miniaturized Extruder to Prototype Amorphous Solid Dispersions: Selection of Plasticizers for Hot Melt Extrusion.

PubMed

Lauer, Matthias E; Maurer, Reto; Paepe, Anne T De; Stillhart, Cordula; Jacob, Laurence; James, Rajesh; Kojima, Yuki; Rietmann, Rene; Kissling, Tom; van den Ende, Joost A; Schwarz, Sabine; Grassmann, Olaf; Page, Susanne

2018-05-19

Hot-melt extrusion is an option to fabricate amorphous solid dispersions and to enhance oral bioavailability of poorly soluble compounds. The selection of suitable polymer carriers and processing aids determines the dissolution, homogeneity and stability performance of this solid dosage form. A miniaturized extrusion device (MinEx) was developed and Hypromellose acetate succinate type L (HPMCAS-L) based extrudates containing the model drugs neurokinin-1 (NK1) and cholesterylester transfer protein (CETP) were manufactured, plasticizers were added and their impact on dissolution and solid-state properties were assessed. Similar mixtures were manufactured with a lab-scale extruder, for face to face comparison. The properties of MinEx extrudates widely translated to those manufactured with a lab-scale extruder. Plasticizers, Polyethyleneglycol 4000 (PEG4000) and Poloxamer 188, were homogenously distributed but decreased the storage stability of the extrudates. Stearic acid was found condensed in ultrathin nanoplatelets which did not impact the storage stability of the system. Depending on their distribution and physicochemical properties, plasticizers can modulate storage stability and dissolution performance of extrudates. MinEx is a valuable prototyping-screening method and enables rational selection of plasticizers in a time and material sparing manner. In eight out of eight cases the properties of the extrudates translated to products manufactured in lab-scale extrusion trials.

Evaluation of Beeswax Influence on Physical Properties of Lipstick Using Instrumental and Sensory Methods.

PubMed

Kasparaviciene, Giedre; Savickas, Arunas; Kalveniene, Zenona; Velziene, Saule; Kubiliene, Loreta; Bernatoniene, Jurga

2016-01-01

The aim of this study was to optimize the lipsticks formulation according to the physical properties and sensory attributes and investigate the relationship between instrumental and sensory analyses and evaluate the influence of the main ingredients, beeswax and oil, with analysis of lipsticks properties. Central composite design was used to optimize the mixture of oils and beeswax and cocoa butter for formulation of lipsticks. Antioxidant activity was evaluated by DPPH free radical scavenging method spectrophotometrically. Physical properties of lipsticks melting point were determined in a glass tube; the hardness was investigated with texture analyzer. Sensory analysis was performed with untrained volunteers. The optimized mixture of sea buckthorn oil and grapeseed oil mixture ratio 13.96 : 6.18 showed the highest antioxidative activity (70 ± 0.84%) and was chosen for lipstick formulation. According to the sensory and instrumental analysis results, optimal ingredients amounts for the lipstick were calculated: 57.67% mixture of oils, 19.58% beeswax, and 22.75% cocoa butter. Experimentally designed and optimized lipstick formulation had good physical properties and high scored sensory evaluation. Correlation analysis showed a significant relationship between sensory and instrumental evaluations.

Evaluation of Beeswax Influence on Physical Properties of Lipstick Using Instrumental and Sensory Methods

PubMed Central

Kasparaviciene, Giedre; Savickas, Arunas; Kalveniene, Zenona; Velziene, Saule; Kubiliene, Loreta

2016-01-01

The aim of this study was to optimize the lipsticks formulation according to the physical properties and sensory attributes and investigate the relationship between instrumental and sensory analyses and evaluate the influence of the main ingredients, beeswax and oil, with analysis of lipsticks properties. Central composite design was used to optimize the mixture of oils and beeswax and cocoa butter for formulation of lipsticks. Antioxidant activity was evaluated by DPPH free radical scavenging method spectrophotometrically. Physical properties of lipsticks melting point were determined in a glass tube; the hardness was investigated with texture analyzer. Sensory analysis was performed with untrained volunteers. The optimized mixture of sea buckthorn oil and grapeseed oil mixture ratio 13.96 : 6.18 showed the highest antioxidative activity (70 ± 0.84%) and was chosen for lipstick formulation. According to the sensory and instrumental analysis results, optimal ingredients amounts for the lipstick were calculated: 57.67% mixture of oils, 19.58% beeswax, and 22.75% cocoa butter. Experimentally designed and optimized lipstick formulation had good physical properties and high scored sensory evaluation. Correlation analysis showed a significant relationship between sensory and instrumental evaluations. PMID:27994631

Formulation and Testing of Paraffin-Based Solid Fuels Containing Energetic Additives for Hybrid Rockets

NASA Technical Reports Server (NTRS)

Larson, Daniel B.; Boyer, Eric; Wachs,Trevor; Kuo, Kenneth K.; Story, George

2012-01-01

Many approaches have been considered in an effort to improve the regression rate of solid fuels for hybrid rocket applications. One promising method is to use a fuel with a fast burning rate such as paraffin wax; however, additional performance increases to the fuel regression rate are necessary to make the fuel a viable candidate to replace current launch propulsion systems. The addition of energetic and/or nano-sized particles is one way to increase mass-burning rates of the solid fuels and increase the overall performance of the hybrid rocket motor.1,2 Several paraffin-based fuel grains with various energetic additives (e.g., lithium aluminum hydride (LiAlH4) have been cast in an attempt to improve regression rates. There are two major advantages to introducing LiAlH4 additive into the solid fuel matrix: 1) the increased characteristic velocity, 2) decreased dependency of Isp on oxidizer-to-fuel ratio. The testing and characterization of these solid-fuel grains have shown that continued work is necessary to eliminate unburned/unreacted fuel in downstream sections of the test apparatus.3 Changes to the fuel matrix include higher melting point wax and smaller energetic additive particles. The reduction in particle size through various methods can result in more homogeneous grain structure. The higher melting point wax can serve to reduce the melt-layer thickness, allowing the LiAlH4 particles to react closer to the burning surface, thus increasing the heat feedback rate and fuel regression rate. In addition to the formulation of LiAlH4 and paraffin wax solid-fuel grains, liquid additives of triethylaluminum and diisobutylaluminum hydride will be included in this study. Another promising fuel formulation consideration is to incorporate a small percentage of RDX as an additive to paraffin. A novel casting technique will be used by dissolving RDX in a solvent to crystallize the energetic additive. After dissolving the RDX in a solvent chosen for its compatibility with both paraffin and RDX, the mixture will be combined with the melted paraffin. With the melting point of the paraffin far below the decomposition temperature of the RDX, the solvent will be boiled off, leaving the crystallized RDX embedded in the paraffin. At low percentages of RDX additive and with crystallized RDX surrounded by paraffin, the fuel grains will remain inert, maintaining a key benefit of hybrids in the safety of the solid fuel.

Use of a CO2 laser to prepare chondrule-like spherules from supercooled molten oxide and silicate droplets.

NASA Technical Reports Server (NTRS)

Nelson, L. S.; Blander, M.; Keil, K.; Skaggs, S. R.

1972-01-01

Chondrule-like spherules were formed from individual freely falling subcooled droplets of alumina, enstatite, forsterite, enstatite-albite and forsterite-albite mixtures that had been melted with a focused continuous CO2 laser beam. Their textures (rimmed, excentro-radial, barred, glassy) are strikingly similar to those of many meteoritic chondrules. It is suggested that the phenomena associated with rapid crystallization from the supercooled melt are responsible for the various textures observed in the artificial spherules as well as in similar meteoritic chondrules. It is suggested that the textures observed would also result from rapid crystallization of relatively slowly cooling molten droplets that may have been produced in larger scale events, including condensation from a nebula of solar composition and solidification in an ambient medium of high temperature.

Stability and corrosion testing of a high temperature phase change material for CSP applications

NASA Astrophysics Data System (ADS)

Liu, Ming; Bell, Stuart; Tay, Steven; Will, Geoffrey; Saman, Wasim; Bruno, Frank

2016-05-01

This paper presents the stability and corrosion testing results of a candidate high temperature phase change material (PCM) for potential use in concentrating solar power applications. The investigated PCM is a eutectic mixture of NaCl and Na2CO3 and both are low cost materials. This PCM has a melting temperature of 635 °C and a relatively high latent heat of fusion of 308.1 J/g. The testing was performed by means of an electric furnace subjected to 150 melt-freeze cycles between 600 °C and 650 °C. The results showed that this PCM candidate has no obvious decomposition up to 650 °C after 150 cycles and stainless steel 316 potentially can be used as the containment material under the minimized oxygen atmosphere.

XMCD and TEM studies of as-cast and rapidly quenched Fe50Nd50 alloys

NASA Astrophysics Data System (ADS)

Menushenkov, V. P.; Menushenkov, A. P.; Shchetinin, I. V.; Wilhelm, F.; Ivanov, A. A.; Rudnev, I. A.; Ivanov, V. G.; Rogalev, A.; Savchenko, A. G.; Zhukov, D. G.; Rafalskiy, A. V.; Ketov, S. V.

2017-12-01

We present the XMCD analysis of as-cast and melt spun Fe50Nd50 samples performed at L2,3 -Nd and K-Fe absorption edges at 5 and 50 K in comparison with macroscopic data of XRD, TEM and magnetic properties measurements. In addition, we have measured the magnetic field dependence of XMCD signal for both types of the samples in magnetic fields up/down to 17 T. The obtained results pointed to the strong difference between structure and magnetic properties of the as-cast and melt spun Fe50Nd50 alloys for both macroscopic and local measurements. The element selective XMCD loops for melt spun alloy show almost identical value of the coercive force Hci for L 2-Nd and K-Fe edges and practically do not depend on temperature. XMCD loop at K-Fe edge is a sum of contributions of the Fe-based phases. The main Fe-rich phase has high Hci ≈ 2,4 T as a highly anisotropic phase. The absence of the K-Fe XMCD loop saturation in the field up to 17 T points to presence of the second Nd-rich Nd-Fe phase which is ferromagnetic at temperature lower than 50 K. In accordance to the TEM results these both phases may coexist as the mixture of nanocrystals which was formed as a result of decomposition of the amorphous-like matrix phase. The XMCD loop at L2 -Nd edge with Hci ≈ 1,9 T is the sum of contributions from two Nd-based phases: hard Fe-rich phase (Hci ≈ 2,4 T) and Nd-Fe matrix phase of medium hardness with Hci ≈ 1,3 T. The macroscopic loop showed the higher Hci compared to XMCD loops. Such discrepancy may be caused by the fact that XMCD signal is collected from a 5-10 mcm thick surface layer, which contains many defects that reduce anisotropy and coercivity.

Morphology of melt-rich channels formed during reaction infiltration experiments on partially molten mantle rocks

NASA Astrophysics Data System (ADS)

Pec, Matej; Holtzman, Benjamin; Zimmerman, Mark; Kohlstedt, David

2016-04-01

Geochemical, geophysical and geological observations suggest that melt extraction from the partially molten mantle occurs by some sort of channelized flow. Melt-solid reactions can lead to melt channelization due to a positive feedback between melt flow and reaction. If a melt-solid reaction increases local permeability, subsequent flow is increased as well and promotes further reaction. This process can lead to the development of high-permeability channels which emerge from background flow. In nature, anastomozing tabular dunite bodies within peridotitic massifs are thought to represent fossilized channels that formed by reactive flow. The conditions under which such channels can emerge are treated by the reaction infiltration instability (RII) theory (e.g. Szymczak and Ladd 2014). In this contribution, we report the results of a series of Darcy type experiments designed to study the development of channels due to RII in mantle lithologies (Pec et al. 2015). We sandwiched a partially molten rock between a melt source and a porous sink and annealed it at high-pressures (P = 300 MPa) and high-temperatures (T = 1200° or 1250° C) under a controlled pressure gradient (∇P = 0-100 MPa/mm) for up to 5 hours. The partially molten rock is formed by 50:50 mixtures of San Carlos olivine (Ol, Fo ˜ 88) and clinopyroxene (Cpx) with either 4, 10 or 20 vol% of alkali basalt added. The source and sink are disks of alkali basalt and porous alumina, respectively. During the experiments, silica undersaturated melt from the melt source dissolves Cpx and precipitates an iron rich Ol (Fo ˜ 82) thereby forming a Cpx-free reaction layer at the melt source - partially molten rock interface. The melt fraction in the reaction layer increases significantly (40% melt) compared to the protolith, confirming that the reaction increases the permeability of the partially molten rock. In experiments annealed under a low pressure gradient (and hence slow melt flow velocity) the reaction layer is planar and no channels develop. However, if the melt migration velocity exceeds ˜5 μm/s the reaction layer locally protrudes into the partially molten rock forming finger-like melt-rich channels. The morphology and spacing of the channels depends on the initial melt fraction. With 20 vol% melt, multiple and voluminous channels with an elliptical core formed of pure melt develop. At lower melt contents, fewer and thinner channels develop. Our experiments demonstrate that melt-rock reactions can lead to melt channelization in mantle lithologies. The morphology of the channels seems to depend on the initial permeability perturbations present in the starting material. The observed lithological transformations are in broad agreement with natural observations. However, the resulting channels lack the tabular anastomozing shapes which are likely caused by shear deformation in nature. Therefore, both reaction-driven as well as stress-driven melt segregation have to interact in nature to form the observed dunite channels. Szymczak, P., and A. J. C. Ladd (2014), Reactive-infiltration instabilities in rocks. Part 2. Dissolution of a porous matrix, J. Fluid Mech., 738, 591-630. Pec, M., B. K. Holtzman, M. Zimmerman, and D. L. Kohlstedt (2015), Reaction infiltration instabilities in experiments on partially molten mantle rocks, Geology, 43(7), 575-578, doi:10.1130/G36611.1.

Petrogenesis of Mare Basalts, Mg-Rich Suites and SNC Parent Magmas

NASA Technical Reports Server (NTRS)

Hess, Paul C.

2004-01-01

The successful models for the internal evolution of the Moon must consider the volume, distribution, timing, composition and, ultimately, the petrogenesis of mare basaltic volcanism. Indeed, given the paucity of geophysical data, the internal state of the Moon in the past can be gleaned only be unraveling the petrogenesis of the various igneous products on the Moon and, particularly, the mare basalts. most useful in constraining the depth and composition of their source region [Delano, 1980] despite having undergone a certain degree of shallow level olivine crystallization.The bulk of the lunar volcanic glass suite can be modeled as the partial melting products of an olivine + orthopyroxene source region deep within the lunar mantle. Ti02 contents vary from 0.2 wt % -1 7.0wt [Shearer and Papike, 1993]. Values that extreme would seem to require a Ti- bearing phase such as ilmenite in the source of the high-Ti (but not in the VLT source) because a source region of primitive LMO olivine and orthopyroxene, even when melted in small degrees cannot account for the observed range of Ti02 compositions. The picritic glasses are undersaturated with respect to ilmenite at all pressures investigated therefore ilmenite must have been consumed during melting, leaving an ilmenite free residue and an undersaturated melt [Delano, 1980, Longhi, 1992, Elkins et al, 2000 among others]. Multi- saturation pressures for the glasses potentially represent the last depths at which the liquids equilibrated with a harzburgite residue before ascending to the surface. These occur at great depths within the lunar mantle. Because the liquids have suffered some amount of crystal fractionation, this is at best a minimum depth. If the melts are mixtures, then it is only an average depth of melting. Multisaturation, nevertheless, is still a strong constraint on source mineralogy, revealing that the generation of the lunar basalts was dominated by melting of olivine and orthopyroxene.

First in-situ monitoring of CO2 delivery to the mantle followed by compression melting, using synchrotron generated X-ray diffraction.

NASA Astrophysics Data System (ADS)

Hammouda, Tahar; Chantel, Julien; Manthilake, Geeth; Guignard, Jérémy; Crichton, Wilson; Gaillard, Fabrice

2014-05-01

Melting of peridotite + CO2 upon compression has been directly monitored in situ, for the first time. We have combined high pressure experiments in the multianvil apparatus with synchrotron-generated X-ray diffraction, in order to monitor sample decarbonation upon heating, followed by melting upon compression. Experiments were performed in the model system CaO-MgO-SiO2+CO2, using dolomite and silicates contained in graphite capsules as starting material. Save Al, starting composition was aimed at reproducing peridotitic system. The sample was first compressed at room temperature, then heated. Decarbonation was observed at 2.2 GPa and 1100°C. After further heating to 1300°C, pressure was increased. Melting was observed at 2.7 GPa, while temperature was kept at 1300°C. All transformations were followed using X-ray diffraction. Starting with silicate + carbonate mixtures, we were thus able to keep CO2 fluid in the experimental sample at high P and T, up to the solidus. Concerning carbon recycling at subduction zones, it is known that CO2 is a non-wetting fluid in silicate aggregates. Therefore, any CO2 resulting from carbonate breakdown likely remains trapped at grain corners either in the subducted lithosphere or in the mantle wedge before eventually being trapped in mantle minerals as fluid inclusions, due to dynamic recrystallization. In this way, CO2 released from the slab may be spread laterally due to mantle convection. Entrainment to further depths by deep subduction or in convection cells induces CO2 introduction to depth wherein the solidus can be crossed, due to pressure increase. The solidus corresponds to the so-called carbonate ledge, beyond which carbonatitic melts are produced. Therefore, compression melting of CO2-bearing lithologies is a way to produce carbonatitic melts at depths corresponding to about 80 km. This mechanism is a viable explanation for the observed geophysical anomalies, such as those revealed by electrical conductivity measurements.

NaF-assisted combustion synthesis of MoSi2 nanoparticles and their densification behavior

NASA Astrophysics Data System (ADS)

Nersisyan, Hayk H.; Lee, Tae Hyuk; Ri, Vladislav; Lee, Jong Hyeon; Suh, Hoyoung; Kim, Jin-Gyu; Son, Hyeon Taek; Kim, Yong-Ho

2017-03-01

The exothermic reduction of oxides mixture (MoO3+2SiO2) by magnesium in NaF melt enables the synthesis of nanocrystalline MoSi2 powders in near-quantitative yields. The combustion wave with temperature of about 1000-1200 °C was recorded in highly diluted by NaF starting mixtures. The by-products of combustion reaction (NaF and MgO) were subsequently removed by leaching with acid and washing with water. The as-prepared MoSi2 nanopowder composed of spherical and dendritic shape particles was consolidated using the spark plasma sintering method at 1200-1500 °C and 50 MPa for 10 min. The result was dense compacts (98.6% theoretical density) possessing submicron grains and exhibiting hardness of 8.74-12.92 GPa.

Tricosane (C23H48) and Octacosane (C28H58) mixture phase transition insight via Light scattering techniques

NASA Astrophysics Data System (ADS)

Kuryakov, V. N.; De Sanctis Lucentini, P. G.; Ivanova, D. D.

2018-04-01

In this study we analyse several emulsion samples of pure Tricosane (C23H48) and Octacosane (C28H58) paraffins as well as their mixtures with different component concentrations, prepared by means of ultrasonic dispersion without the addition of surfactants. We show that from the measurements of Static Light Scattering temperature dependences it is possible to determine the phase transition temperatures of the paraffins emulsion during the heating and cooling cycles (melting, crystallization and rotator phases). The results for the pure paraffin are in good agreement with the literature data. We produce the outcomes of the Dynamic Light Scattering technique to determine the cluster size of the obtained emulsions (radius 70-120 nm). Those emulsions proved to remain stable during several months.

Heat storage system utilizing phase change materials government rights

DOEpatents

Salyer, Ival O.

2000-09-12

A thermal energy transport and storage system is provided which includes an evaporator containing a mixture of a first phase change material and a silica powder, and a condenser containing a second phase change material. The silica powder/PCM mixture absorbs heat energy from a source such as a solar collector such that the phase change material forms a vapor which is transported from the evaporator to the condenser, where the second phase change material melts and stores the heat energy, then releases the energy to an environmental space via a heat exchanger. The vapor is condensed to a liquid which is transported back to the evaporator. The system allows the repeated transfer of thermal energy using the heat of vaporization and condensation of the phase change material.

A hydrometric and geochemical approach to test the transmissivity feedback hypothesis during snowmelt

USGS Publications Warehouse

Kendall, K.A.; Shanley, J.B.; McDonnell, Jeffery J.

1999-01-01

To test the transmissivity feedback hypothesis of runoff generation, surface and subsurface waters were monitored and sampled during the 1996 snowmelt at various topographic positions in a 41 ha forested headwater catchment at Sleepers River, Vermont. Two conditions that promote transmissivity feedback existed in the catchment during the melt period. First, saturated hydraulic conductivity increased toward land surface, from a geometric mean of 3.6 mm h-1 in glacial till to 25.6 mm h-1 in deep soil to 54.0 mm h-1 in shallow soil. Second, groundwater levels rose to within 0.3 m of land surface at all riparian sites and most hillslope sites at peak melt. The importance of transmissivity feedback to streamflow generation was tested at the catchment scale by examination of physical and chemical patterns of groundwater in near-stream (discharge) and hillslope (recharge/lateral flow) zones, and within a geomorphic hollow (convergent flow). The presence of transmissivity feedback was supported by the abrupt increase in streamflow as the water table rose into the surficial, transmissive zone; a flattening of the groundwater level vs. streamflow curve occurred at most sites. This relation had a clockwise hysteresis (higher groundwater level for given discharge on rising limb than at same discharge on falling limb) at riparian sites, suggesting that the riparian zone was the dominant source area during the rising limb of the melt hydrograph. Hysteresis was counterclockwise at hillslope sites, suggesting that hillslope drainage controlled the snowmelt recession. End member mixing analysis using Ca, Mg, Na, dissolved organic carbon (DOC), and Si showed that stream chemistry could be explained as a two-component mixture of groundwater high in base cations and an O-horizon/overland flow water high in DOC. The dominance of shallow flow paths during events was indicated by the high positive correlation of DOC with streamflow (r2 = 0.82). Despite the occurrence of transmissivity feedback, hillslope till and soil water were ruled out as end members primarily because their distinctive high-Si composition had little or no effect on streamwater composition. Till water from the geomorphic hollow had a chemistry very close to streamwater base flow, and may represent the base flow end member better than the more concentrated riparian groundwater. During snowmelt, streamwater composition shifted as this base flow was diluted - not by shallow groundwater from the hillslope, but rather by a more surficial O-horizon/overland flow water.Surface and subsurface waters were analyzed to test the transmissivity feedback of runoff generation during the 1996 snowmelt in a catchment at Sleepers River, Vermont. The importance of transmissivity feedback to stream flow generation was tested by examination of physical and chemical patterns of groundwater in near-stream and hillslope zones within a geomorphic hollow. End member mixing analysis of Ca, Mg, Na, dissolved organic carbon (DOC), and Si showed that stream chemistry could be explained as a two-component mixture of groundwater high in base cations and an O-horizon/overland flow water high in DOC. The dominance of shallow water paths during the events was indicated by the high positive correlation of DOC with streamflow (r2 = 0.82).

Molten nitrate salt technology development

NASA Astrophysics Data System (ADS)

Carling, R. W.

1981-04-01

This paper presents an overview of the experimental programs underway in support of the Thermal Energy Storage for Solar Thermal Applications (TESSTA) program. The experimental programs are concentrating on molten nitrate salts which have been proposed as heat transfer and energy storage medium. The salt composition of greatest interest is drawsalt, nominally a 50-50 molar mixture of NaNO3 and KNO3 with a melting point of 220 C. Several technical uncertainties have been identified that must be resolved before nitrate based solar plants can be commercialized. Research programs at Sandia National Laboratories, universities, and industrial suppliers have been implemented to resolve these technical uncertainties. The experimental programs involve corrosion, decomposition, physical properties, and environmental cracking. Summaries of each project and how they impact central receiver applications such as the repowering/industrial retrofit and cogeneration program are presented.

Water/rock interactions in experimentally simulated dirty snowball and dirty iceball cometary nuclei

NASA Technical Reports Server (NTRS)

Gooding, James L.; Allton, Judith H.

1991-01-01

In the dirty snowball model for cometary nuclei, comet-nucleus materials are regarded as mixtures of volatile ices and relatively non-volatile minerals or chemical compounds. Carbonaceous chondrite meteorites are regarded as useful analogs for the rocky component. To help elucidate the possible physical geochemistry of cometary nuclei, preliminary results are reported of calorimetric experiments with two-component systems involving carbonaceous chondrites and water ice. Based on collective knowledge of the physics of water ice, three general types of interactions can be expected between water and minerals at sub-freezing temperatures: (1) heterogeneous nucleation of ice by insoluble minerals; (2) adsorption of water vapor by hygroscopic phases; and (3) freezing- and melting-point depression of liquid water sustained by soluble minerals. The relative and absolute magnitude of all three effects are expected to vary with mineral composition.

Research into the rationality and the application scopes of different melting models of nanoparticles

NASA Astrophysics Data System (ADS)

Fu, Qingshan; Xue, Yongqiang; Cui, Zixiang; Duan, Huijuan

2017-07-01

A rational melting model is indispensable to address the fundamental issue regarding the melting of nanoparticles. To ascertain the rationality and the application scopes of the three classical thermodynamic models, namely Pawlow, Rie, and Reiss melting models, corresponding accurate equations for size-dependent melting temperature of nanoparticles were derived. Comparison of the melting temperatures of Au, Al, and Sn nanoparticles calculated by the accurate equations with available experimental results demonstrates that both Reiss and Rie melting models are rational and capable of accurately describing the melting behaviors of nanoparticles at different melting stages. The former (surface pre-melting) is applicable to the stage from initial melting to critical thickness of liquid shell, while the latter (solid particles surrounded by a great deal of liquid) from the critical thickness to complete melting. The melting temperatures calculated by the accurate equation based on Reiss melting model are in good agreement with experimental results within the whole size range of calculation compared with those by other theoretical models. In addition, the critical thickness of liquid shell is found to decrease with particle size decreasing and presents a linear variation with particle size. The accurate thermodynamic equations based on Reiss and Rie melting models enable us to quantitatively and conveniently predict and explain the melting behaviors of nanoparticles at all size range in the whole melting process. [Figure not available: see fulltext.

Development of MPS Method for Analyzing Melt Spreading Behavior and MCCI in Severe Accidents

NASA Astrophysics Data System (ADS)

Yamaji, Akifumi; Li, Xin

2016-08-01

Spreading of molten core (corium) on reactor containment vessel floor and molten corium-concrete interaction (MCCI) are important phenomena in the late phase of a severe accident for assessment of the containment integrity and managing the severe accident. The severe accident research at Waseda University has been advancing to show that simulations with moving particle semi-implicit (MPS) method (one of the particle methods) can greatly improve the analytical capability and mechanical understanding of the melt behavior in severe accidents. MPS models have been developed and verified regarding calculations of radiation and thermal field, solid-liquid phase transition, buoyancy, and temperature dependency of viscosity to simulate phenomena, such as spreading of corium, ablation of concrete by the corium, crust formation and cooling of the corium by top flooding. Validations have been conducted against experiments such as FARO L26S, ECOKATS-V1, Theofanous, and SPREAD for spreading, SURC-2, SURC-4, SWISS-1, and SWISS-2 for MCCI. These validations cover melt spreading behaviors and MCCI by mixture of molten oxides (including prototypic UO2-ZrO2), metals, and water. Generally, the analytical results show good agreement with the experiment with respect to the leading edge of spreading melt and ablation front history of concrete. The MPS results indicate that crust formation may play important roles in melt spreading and MCCI. There is a need to develop a code for two dimensional MCCI experiment simulation with MPS method as future study, which will be able to simulate anisotropic ablation of concrete.

Mechanochemical Synthesis of Pharmaceutical Cocrystal Suspensions via Hot Melt Extrusion: Feasibility Studies and Physicochemical Characterization.

PubMed

Li, Shu; Yu, Tao; Tian, Yiwei; McCoy, Colin P; Jones, David S; Andrews, Gavin P

2016-09-06

Engineered cocrystals offer an alternative solid drug form with tailored physicochemical properties. Interestingly, although cocrystals provide many new possibilities, they also present new challenges, particularly in regard to their design and large-scale manufacture. Current literature has primarily focused on the preparation and characterization of novel cocrystals typically containing only the drug and coformer, leaving the subsequent formulation less explored. In this paper we propose, for the first time, the use of hot melt extrusion for the mechanochemical synthesis of pharmaceutical cocrystals in the presence of a meltable binder. In this approach, we examine excipients that are amenable to hot melt extrusion, forming a suspension of cocrystal particulates embedded in a pharmaceutical matrix. Using ibuprofen and isonicotinamide as a model cocrystal reagent pair, formulations extruded with a small molecular matrix carrier (xylitol) were examined to be intimate mixtures wherein the newly formed cocrystal particulates were physically suspended in a matrix. With respect to formulations extruded using polymeric carriers (Soluplus and Eudragit EPO, respectively), however, there was no evidence within PXRD patterns of either crystalline ibuprofen or the cocrystal. Importantly, it was established in this study that an appropriate carrier for a cocrystal reagent pair during HME processing should satisfy certain criteria including limited interaction with parent reagents and cocrystal product, processing temperature sufficiently lower than the onset of cocrystal Tm, low melt viscosity, and rapid solidification upon cooling.

Vitrification of organics-containing wastes

DOEpatents

Bickford, D.F.

1995-01-01

A process for stabilizing organics-containing waste materials and recovery metals therefrom, and a waste glass product made according to the process are described. Vitrification of wastes such as organic ion exchange resins, electronic components and the like can be accomplished by mixing at least one transition metal oxide with the wastes, and, if needed, glass formers to compensate for a shortage of silicates or other glass formers in the wastes. The transition metal oxide increases the rate of oxidation of organic materials in the wastes to improve the composition of the glass-forming mixture: at low temperatures, the oxide catalyzes oxidation of a portion of the organics in the waste; at higher temperatures, the oxide dissolves and the resulting oxygen ions oxidize more of the organics; and at vitrification temperatures, the metal ions conduct oxygen into the melt to oxidize the remaining organics. In addition, the transition metal oxide buffers the redox potential of the glass melt so that metals such as Au, Pt, Ag, and Cu separate form the melt in the metallic state and can be recovered. After the metals are recovered, the remainder of the melt is allowed to cool and may subsequently be disposed of. The product has good leaching resistance and can be disposed of in an ordinary landfill, or, alternatively, used as a filler in materials such as concrete, asphalt, brick and tile.

Vitrification of organics-containing wastes

DOEpatents

Bickford, Dennis F.

1997-01-01

A process for stabilizing organics-containing waste materials and recovering metals therefrom, and a waste glass product made according to the process. Vitrification of wastes such as organic ion exchange resins, electronic components and the like can be accomplished by mixing at least one transition metal oxide with the wastes, and, if needed, glass formers to compensate for a shortage of silicates or other glass formers in the wastes. The transition metal oxide increases the rate of oxidation of organic materials in the wastes to improve the composition of the glass-forming mixture: at low temperatures, the oxide catalyzes oxidation of a portion of the organics in the waste; at higher temperatures, the oxide dissolves and the resulting oxygen ions oxidize more of the organics; and at vitrification temperatures, the metal ions conduct oxygen into the melt to oxidize the remaining organics. In addition, the transition metal oxide buffers the redox potential of the glass melt so that metals such as Au, Pt, Ag, and Cu separate from the melt in the metallic state and can be recovered. After the metals are recovered, the remainder of the melt is allowed to cool and may subsequently be disposed of. The product has good leaching resistance and can be disposed of in an ordinary landfill, or, alternatively, used as a filler in materials such as concrete, asphalt, brick and tile.

Vitrification of organics-containing wastes

DOEpatents

Bickford, D.F.

1997-09-02

A process is described for stabilizing organics-containing waste materials and recovering metals therefrom, and a waste glass product made according to the process is also disclosed. Vitrification of wastes such as organic ion exchange resins, electronic components and the like can be accomplished by mixing at least one transition metal oxide with the wastes, and, if needed, glass formers to compensate for a shortage of silicates or other glass formers in the wastes. The transition metal oxide increases the rate of oxidation of organic materials in the wastes to improve the composition of the glass-forming mixture: at low temperatures, the oxide catalyzes oxidation of a portion of the organics in the waste; at higher temperatures, the oxide dissolves and the resulting oxygen ions oxidize more of the organics; and at vitrification temperatures, the metal ions conduct oxygen into the melt to oxidize the remaining organics. In addition, the transition metal oxide buffers the redox potential of the glass melt so that metals such as Au, Pt, Ag, and Cu separate from the melt in the metallic state and can be recovered. After the metals are recovered, the remainder of the melt is allowed to cool and may subsequently be disposed of. The product has good leaching resistance and can be disposed of in an ordinary landfill, or, alternatively, used as a filler in materials such as concrete, asphalt, brick and tile. 1 fig.

Control of Morphology of Crystallizable Polymer Mixtures via Manipulation of the Heterogeneous Melt

DTIC Science & Technology

1990-11-09

Distribution of Matrix Homopolymer C.V. Berney in Block Copolymers of Spherical P. Cheng Morphology R.E. Cohen 2. Distribution of Chain Ends Inside P. Cheng...the Polybutadiene Microspheres of SB C.V. Berney Diblock Copolymers R.E. Cohen 3. Spatial Organization of Homopolymer P. Cheng Chains Inside Spherical...Polybutadiene C.V. Berney Domains of SB Diblock Copolymers R.E. Cohen 4. Blends of Crystallizable Polybutadienes M. Marx R.E. Cohen 5. Synthesis and

Densified Biomass as an Alternative Army Heating and Power Plant Fuel.

DTIC Science & Technology

1980-03-01

during all fuel handling operations, par- ticularly where there were long drops-in the elevator Rock Island Arsenall, IL pit and bunker area , for...intebkrmoeha3dysndvrgsaou an effective grate area of 90 sq ft (8.4 in2). The stoker consists of two independent, self-cleaning, automatic! 1 day. manual, heat...the pellet/fines quantity of free moisture from melting snow during mixture was distributed into the designated area of outside storage. the bunker

Abrasion-Resistant Aluminized-Coated Aramid Fabrics for Manufacture of Firefighters’ Protective Clothing

DTIC Science & Technology

1985-05-01

OK 3-600 IV -5 D. ELECTRON-BEAM (EB) CURABLE "OATINGS These coatings are formed by curing or crosslinking a complex mixture of multifunctional acrylic ...1. 8p. Cooper, B.E., D.W. Butler, inventors; Dow Coming Corp., assignee. Curable siloxane resin coating composition. EP patent 048,114. (1982) March...limit use in the water-prone firefighters environment. We believe other high-temperature melting resins , such as polysulfone or polyether-imide, would

Effective recovery of poly-β-hydroxybutyrate (PHB) biopolymer from Cupriavidus necator using a novel and environmentally friendly solvent system.

PubMed

Fei, Tao; Cazeneuve, Stacy; Wen, Zhiyou; Wu, Lei; Wang, Tong

2016-05-01

This work demonstrates a significant advance in bioprocessing for a high-melting lipid polymer. A novel and environmental friendly solvent mixture, acetone/ethanol/propylene carbonate (A/E/P, 1:1:1 v/v/v) was identified for extracting poly-hydroxybutyrate (PHB), a high-value biopolymer, from Cupriavidus necator. A set of solubility curves of PHB in various solvents was established. PHB recovery of 85% and purity of 92% were obtained from defatted dry biomass (DDB) using A/E/P. This solvent mixture is compatible with water, and from non-defatted wet biomass, PHB recovery of 83% and purity of 90% were achieved. Water and hexane were evaluated as anti-solvents to assist PHB precipitation, and hexane improved recovery of PHB from biomass to 92% and the purity to 93%. A scale-up extraction and separation reactor was designed, built and successfully tested. Properties of PHB recovered were not significantly affected by the extraction solvent and conditions, as shown by average molecular weight (1.4 × 10(6) ) and melting point (175.2°C) not being different from PHB extracted using chloroform. Therefore, this biorenewable solvent system was effective and versatile for extracting PHB biopolymers. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:678-685, 2016. © 2016 American Institute of Chemical Engineers.

Effect of salts on the properties of aqueous sugar systems, in relation to biomaterial stabilization. 1. Water sorption behavior and ice crystallization/melting.

PubMed

Mazzobre, M F; Longinotti, M P; Corti, H R; Buera, M P

2001-11-01

Trehalose and sucrose, two sugars that are involved in the protection of living organisms under extreme conditions, and their mixtures with salts were employed to prepare supercooled or freeze-dried glassy systems. The objective of the present work was to explore the effects of different salts on water sorption, glass transition temperature (T(g)), and formation and melting of ice in aqueous sugar systems. In the sugar-salt mixtures, water adsorption was higher than expected on the basis of the water uptake by each pure component. In systems with a reduced mass fraction of water (w less-than-or-equal 0.4), salts delayed water crystallization, probably due to ion-water interactions. In systems where > 0.6, water crystallization could be explained by the known colligative properties of the solutes. The glass transition temperature of the maximally concentrated matrix (T(g)') was decreased by the presence of salts. However, the actual T(g) values of the systems were not modified. Thus, the effect of salts on sorption behavior and formation of ice may reflect dynamic water-salt-sugar interactions which take place at a molecular level and are related to the charge/mass ratio of the cation present without affecting supramolecular or macroscopic properties. Copyright 2001 Elsevier Science (USA).

Alternative Gas Mixtures in Arc Spraying: A Chance to Improve Coating Properties and Residual Stress States

NASA Astrophysics Data System (ADS)

Hauer, Michél; Henkel, Knuth Michael; Krebs, Sebastian; Kroemmer, Werner

2018-01-01

The highly cavitation erosion-resistant propeller alloys CuAl9Ni5Fe4Mn (Ni-Al-Bronze) and CuMn13Al8Fe3Ni2 (Mn-Al-Bronze) were arc-sprayed using a mixture of nitrogen and 2% of hydrogen as atomizing gas and different traverse speeds. The objective was to identify the influences of the different spraying conditions, such as temperature regime and melting loss, on the resulting residual stress states and coating properties. Residual stresses were measured by the incremental hole-drilling method using ESPI. Temperature measurements were carried out by thermographic imaging. Microstructural, chemical and mechanical analyses were realized to examine adhesive and cohesive properties. Additionally, the cavitation erosion behavior was investigated to analyze cohesive coating properties. The spraying process itself was improved, which was apparent by mainly enhanced deposition efficiency and reduced surface temperatures. The amount of oxides and pores as well as the melting loss of alloying elements were reduced. Moreover, an increased cavitation erosion resistance and thus coating cohesion as well as less residual stresses were identified. The change in atomizing gas diminished the impact of the quenching stresses on the coating properties. In contrast, the adhesive strength, Young's moduli and partially the hardness were slightly reduced. With regard to materials, Ni-Al-Bronze revealed superior coating properties in comparison with Mn-Al-Bronze.

Investigation of the combined effect of MgO and PEG on the release profile of mefenamic acid prepared via hot-melt extrusion techniques.

PubMed

Alshehri, Sultan M; Tiwari, Roshan V; Alsulays, Bader B; Ashour, Eman A; Alshetaili, Abdullah S; Almutairy, Bjad; Park, Jun-Bom; Morott, Joseph; Sandhu, Bhupinder; Majumdar, Soumyajit; Repka, Michael A

2017-09-01

This study aimed to investigate the combined effect of magnesium oxide (MgO) as an alkalizer and polyethylene glycol (PEG) as a plasticizer and wetting agent in the presence of Kollidon® 12 PF and 17 PF polymer carriers on the release profile of mefenamic acid (MA), which was prepared via hot-melt extrusion technique. Various drug loads of MA and various ratios of the polymers, PEG 3350 and MgO were blended using a V-shell blender and extruded using a twin-screw extruder (16-mm Prism EuroLab, ThermoFisher Scientific, Carlsbad, CA) at different screw speeds and temperatures to prepare a solid dispersion system. Differential scanning calorimetry and X-ray diffraction data of the extruded material confirmed that the drug existed in the amorphous form, as evidenced by the absence of corresponding peaks. MgO and PEG altered the micro-environmental pH to be more alkaline (pH 9) and increased the hydrophilicity and dispersibility of the extrudates to enhance MA solubility and release, respectively. The in vitro release study demonstrated an immediate release for 2 h with more than 80% drug release within 45 min in matrices containing MgO and PEG in combination with polyvinylpyrrolidone when compared to the binary mixture, physical mixture and pure drug.

Studies on the muscle-paralyzing components of the juice of the banana plant.

PubMed

Singh, Y N; Inman, W D; Johnson, A; Linnell, E J

1993-01-01

The stem juice of the banana plant (Musa species) has been used as an arrow poison by African tribesmen. Lyophilized, partially purified extracts of the juice augment and then block both directly and indirectly evoked contractions of the mouse diaphragm. We have isolated, purified and determined the chemical composition of the active ingredients, and characterized their pharmacological activity. The lyophilized sample was extracted with a methanol-water (MeOH-H2O) (50/50) mixture and vacuum filtered. The filtrate was rotary evaporated and crystallized in a MeOH-H2O mixture to yield potassium nitrate crystals (melting point 332-334 degrees C). The filtrate was concentrated and chromatographed over Sephadex LH-20 gel using MeOH-H2O (40/60) as the eluent. The active component was found to be magnesium nitrate crystals (melting point 87-89 degrees C). In the mouse isolated phrenic nerve-hemidiaphragm preparation, the pharmacological profile of the first component was similar to that for authentic potassium nitrate which augments in low concentrations, and in higher concentrations augments, and then blocks both directly evoked muscle contraction the neuromuscular transmission. The second component had a profile of activity similar to that for authentic magnesium nitrate which only blocks neuromuscular transmission. It can be concluded that the two major active principles in the banana stem juice are potassium nitrate and magnesium nitrate.

Interaction of peridotite with Ca-rich carbonatite melt at 3.1 and 6.5 GPa: Implication for merwinite formation in upper mantle, and for the metasomatic origin of sublithospheric diamonds with Ca-rich suite of inclusions

NASA Astrophysics Data System (ADS)

Sharygin, Igor S.; Shatskiy, Anton; Litasov, Konstantin D.; Golovin, Alexander V.; Ohtani, Eiji; Pokhilenko, Nikolay P.

2018-03-01

We performed an experimental study, designed to reproduce the formation of an unusual merwinite + olivine-bearing mantle assemblage recently described as a part of a Ca-rich suite of inclusions in sublithospheric diamonds, through the interaction of peridotite with an alkali-rich Ca-carbonatite melt, derived from deeply subducted oceanic crust. In the first set of experiments, we studied the reaction between powdered Mg-silicates, olivine and orthopyroxene, and a model Ca-carbonate melt (molar Na:K:Ca = 1:1:2), in a homogeneous mixture, at 3.1 and 6.5 GPa. In these equilibration experiments, we observed the formation of a merwinite + olivine-bearing assemblage at 3.1 GPa and 1200 °C and at 6.5 GPa and 1300-1400 °C. The melts coexisting with this assemblage have a low Si and high Ca content (Ca# = molar 100 × Ca/(Ca + Mg) > 0.57). In the second set of experiments, we investigated reaction rims produced by interaction of the same Ca-carbonate melt (molar Na:K:Ca = 1:1:2) with Mg-silicate, olivine and orthopyroxene, single crystals at 3.1 GPa and 1300 °C and at 6.5 GPa and 1400 °C. The interaction of the Ca-carbonate melt with olivine leads to merwinite formation through the expected reaction: 2Mg2SiO4 (olivine) + 6CaCO3 (liquid) = Ca3MgSi2O8 (merwinite) + 3CaMg(CO3)2 (liquid). Thus, our experiments confirm the idea that merwinite in the upper mantle may originate via interaction of peridotite with Ca-rich carbonatite melt, and that diamonds hosting merwinite may have a metasomatic origin. It is remarkable that the interaction of the Ca-carbonate melt with orthopyroxene crystals does not produce merwinite both at 3.1 and 6.5 GPa. This indicates that olivine grain boundaries are preferable for merwinite formation in the upper mantle.