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Sample records for immiscible elements ag-fe

  1. Finite-Element Analysis of Multiphase Immiscible Flow Through Soils

    NASA Astrophysics Data System (ADS)

    Kuppusamy, T.; Sheng, J.; Parker, J. C.; Lenhard, R. J.

    1987-04-01

    A finite-element model is developed for multiphase flow through soil involving three immiscible fluids: namely, air, water, and a nonaqueous phase liquid (NAPL). A variational method is employed for the finite-element formulation corresponding to the coupled differential equations governing flow in a three-fluid phase porous medium system with constant air phase pressure. Constitutive relationships for fluid conductivities and saturations as functions of fluid pressures, which are derived in a companion paper by J. C. Parker et al. (this issue) and which may be calibrated from two-phase laboratory measurements, are employed in the finite-element program. The solution procedure uses backward time integration with iteration by a modified Picard method to handle the nonlinear properties. Laboratory experiments involving water displacement from soil columns by p cymene (a benzene-derivative hydrocarbon) under constant pressure were simulated by the finite-element program to validate the numerical model and formulation for constitutive properties. Transient water outflow predicted using independently measured saturation-capillary head data agreed with observed outflow data within the limits of precision of the predictions as estimated by a first-order Taylor series approximation considering parameter uncertainty due to experimental reproducability and constitutive model accuracy. Two-dimensional simulations are presented for a hypothetical field case involving introduction of NAPL near the soil surface due to leakage from an underground storage tank. Subsequent transport of NAPL in the variably saturated vadose and groundwater zones is analyzed.

  2. Fabrication of bimetallic Ag/Fe immobilized on modified biochar for removal of carbon tetrachloride.

    PubMed

    Wu, Hongwei; Feng, Qiyan

    2017-04-01

    As an effective conventional absorbent, biochar exhibited limited adsorption ability toward small hydrophobic molecules. To enhance the adsorption capacity, a novel adsorbent was prepared by immobilizing nanoscale zero-valent iron onto modified biochar (MB) and then the elemental silver was attached to the surface of iron (Ag/Fe/MB). It's noted that spherical Ag/Fe nanoparticles with diameter of 51nm were highly dispersed on the surface of MB. As the typical hydrophobic contaminant, carbon tetrachloride was selected for examining the removal efficiency of the adsorbent. The removal efficiencies of carbon tetrachloride by original biochar (OB), Ag/Fe, Ag/Fe/OB and Ag/Fe/MB were fully investigated. It's found that Ag/Fe/MB showed higher carbon tetrachloride removal efficiency, which is about 5.5 times higher than that of the OB sample due to utilizing the merits of high adsorption and reduction. Thermodynamic parameters revealed that the removal of carbon tetrachloride by Ag/Fe/MB was a spontaneous and exothermic process, which was affected by solution pH, initial carbon tetrachloride concentration and temperature. The novel Ag/Fe/MB composites provided a promising material for carbon tetrachloride removal from effluent. Copyright © 2016. Published by Elsevier B.V.

  3. Asymmetric interfaces in Fe/Ag and Ag/Fe bilayers prepared by molecular beam evaporation

    NASA Astrophysics Data System (ADS)

    Tunyogi, A.; Pászti, F.; Osváth, Z.; Tanczikó, F.; Major, M.; Szilágyi, E.

    2006-08-01

    Single layers of Fe and Ag, as well as Fe/Ag (iron deposited first) and Ag/Fe bilayers were prepared by molecular beam evaporation onto Si. The samples were investigated with backscattering spectrometry (BS) and atomic force microscopy (AFM). BS spectra of Fe/Ag and Ag/Fe indicate a significant difference at the interface. In the case of Fe/Ag the Ag peak has a long tail at the interface, while for Ag/Fe the interface is abrupt. The tail in the Fe/Ag spectrum is too large to be caused by double or plural scattering. According to AFM, the effect of surface roughness is also negligible. In spite of the fact that Fe and Ag are completely immiscible in equilibrium, this tail, however, suggests that some Ag is located in the Fe layer. After annealing, both samples show mixing between the two layers; this is much larger again for Fe/Ag.

  4. Fabrication and magnetic properties of glass-coated microwires from immiscible elements

    NASA Astrophysics Data System (ADS)

    Zhukov, A.; Sinnecker, E. H. C. P.; Paramo, D.; Guerrero, F.; Larin, V.; González, J.; Vázquez, M.

    1999-04-01

    The Taylor-Ulitovski technique has been successfully employed to fabricate glass-coated microwires having internal nucleus made of alloys of various immiscible elements. Series of alloys CoxCu100-x, Co29Ni25Mn1Cu45, and (FeSiBC)50Cu50 have been studied from structural and magnetic points of view. The influence of thermal treatments on the structure and magnetic properties has been moreover studied with a final aim to obtain such type of microwires with enhanced hard magnetic properties. A maximum coercivity of around 750 Oe is achieved in the optimum conditions.

  5. Effects of liquid immiscibility on trace element fractionation in magmatic iron meteorites: A case study of group IIIAB

    NASA Astrophysics Data System (ADS)

    Ulff-Moeller, Finn

    1998-03-01

    Magmatic iron meteorites are generally agreed to represent metal that crystallized in asteroidal cores from a large pool of liquid. Estimates suggest that the metallic liquid contained significant amounts of S and P, both of which are incompatible and exert a strong effect on trace-element partitioning. In tandem, S and P are also prone to cause immiscibility between sulfide liquid and P-rich metal liquid. The liquid immiscibility field occupies about 70% of the portion of the Fe-Ni-S-P system in which iron is the first phase to crystallize. In spite of this, previous fractional crystallization models have taken into account only one liquid phase and have encountered significant discrepancies between the meteorite data and model values for the key elements Ni, Ir, Ga, Ge and Au at even moderate degrees of fractionation. For the first time, a model for trace-element partitioning between immiscible liquids in the Fe-Ni-S-P system is presented in order to assess the effects on fractionation in magmatic iron meteorite groups. The onset of liquid immiscibility causes a significant change in the enrichment patterns of S and P in both liquids, so elements with contrasting partitioning behavior will show trends deviating clearly from one-liquid trends. A trend recorded in the solid metal will either be a smooth curve as long as equilibrium is maintained between the two liquids or the trend may diverge into a field limited by two extreme curves depending on the degree of disequilibrium. Bulk initial liquids for most magmatic groups have S/P (wt%) ratios well below 25. In these cases, and due to the constitution of the Fe-Ni-S-P system, most of the metal will crystallize from the rapidly decreasing volume of metal liquid and only a subordinate amount from the sulfide liquid. Because of the strong extraction of P into the metal liquid, P will have a much larger influence on trace-element partitioning than a low initial P content might suggest. My model calculations suggest

  6. Rare earth element selenochemistry of immiscible liquids and zircon at Apollo 14 - An ion probe study of evolved rocks on the moon

    NASA Technical Reports Server (NTRS)

    Snyder, Gregory A.; Taylor, Lawrence A.; Crozaz, Ghislaine

    1993-01-01

    Results are presented of trace-element analyses of three lunar zircons. The major-element and REE compositions were determined using electron microprobes, and a correction was made for zircon for Zr-Si-O molecular interferences in the La to Pr mass region. The three zircons were found to exhibit similar REE abundances and patterns. Results of the analyses confirm earlier studies (Hess et al., 1975; Watson, 1976; Neal and Taylor, 1989) on the partitioning behavior of trace elements in immiscible liquid-liquid pairs. The results also support the postulated importance of silicate liquid immiscibility in the differentiation of the upper mantle and crust of the moon.

  7. Rare earth element selenochemistry of immiscible liquids and zircon at Apollo 14 - An ion probe study of evolved rocks on the moon

    NASA Technical Reports Server (NTRS)

    Snyder, Gregory A.; Taylor, Lawrence A.; Crozaz, Ghislaine

    1993-01-01

    Results are presented of trace-element analyses of three lunar zircons. The major-element and REE compositions were determined using electron microprobes, and a correction was made for zircon for Zr-Si-O molecular interferences in the La to Pr mass region. The three zircons were found to exhibit similar REE abundances and patterns. Results of the analyses confirm earlier studies (Hess et al., 1975; Watson, 1976; Neal and Taylor, 1989) on the partitioning behavior of trace elements in immiscible liquid-liquid pairs. The results also support the postulated importance of silicate liquid immiscibility in the differentiation of the upper mantle and crust of the moon.

  8. Decoupling of paired elements, crossover REE patterns, and mirrored spider diagrams: Fingerprinting liquid immiscibility in the Tapira alkaline-carbonatite complex, SE Brazil

    NASA Astrophysics Data System (ADS)

    Brod, José Affonso; Junqueira-Brod, Tereza Cristina; Gaspar, José Carlos; Petrinovic, Ivan Alejandro; Valente, Sérgio de Castro; Corval, Artur

    2013-01-01

    Tapira is an alkaline silicate-carbonatite complex belonging to the kamafugite-carbonatite association in the Late-Cretaceous Alto Paranaíba Igneous Province (APIP). It is dominated by coarse-grained plutonic rocks (bebedourite - a phlogopite-, apatite-, and perovskite-rich clinopyroxenite - with subordinated dunites, wehrlites, carbonatites and phoscorites). The plutonic rocks are crosscut by fine-grained ultramafic alkaline rocks (phlogopite picrites, bebedouritic dikes) and fine-grained carbonatites. Both types of dike-rocks show petrographic evidence of the coexistence of immiscible silicate and carbonatite liquids, such as carbonate ocelli present in the silicate rocks and, more rarely, silicate ocelli within carbonatites. A detailed geochemical study of the rock types in the complex, with emphasis on the fine-grained varieties, showed that whilst some rocks may be related to each other through crystal fractionation (e.g. phlogopite picrites and bebedouritic dikes), others display anomalous trace-element behaviour that cannot be readily explained by the fractionation of a particular phase or combination of phases. We interpret such anomalous geochemical signatures as produced by silicate-carbonate liquid immiscibility, on the basis of available experimental data on partition coefficients between coexisting immiscible liquids. The immiscibility signatures comprise: (a) decoupling of geochemical pairs, such as Nb-Ta and Zr-Hf; (b) rotation of REE patterns, which cross over the patterns of the primitive liquids; and (c) matching and opposite enrichment-depletion trace elements relationships in spider diagrams of conjugate immiscible liquids. We suggest that, once established, such geochemical signatures are very difficult to erase during the subsequent petrogenetic evolution processes, which may result in superimposed conflicting signatures.

  9. Tunable and enhanced SERS activity of magneto-plasmonic Ag-Fe3O4 nanocomposites with one pot synthesize method

    NASA Astrophysics Data System (ADS)

    Fan, Chunzhen; Zhu, Shuangmei; Xin, Haoyi; Tian, Yuchen; Liang, Erjun

    2017-01-01

    In this paper, we report the tunable and enhanced SERS activity of magneto-plasmonic Ag-Fe3O4 nanocomposites that are synthesized by a one pot method. Crystal violet (CV), rhodamine 6 G (R6G) and 4-mercaptobenzoic acid (4-MBA) molecules are used to investigate the SERS optical activity of Ag-Fe3O4 nanocomposites under different external magnetic fields (1500, 2000, 2500, 3500 and 5000 gauss). The experimental results demonstrate the enhanced Raman effects that can be obtained by increasing the magnitude of external magnetic field. This is because the electromagnetic hot spots located between the neighboring Ag-Fe3O4 nanocomposites can be tuned by utilizing the external magnetic field. The bigger density of the hot-spots and amplitude of the electric field in the hot-spot are responsible for the enhanced SERS effect. The detection limit of CV molecule can be at least down to 10-9 M. The spectra measurements of hemoglobin adsorbed on the Ag-Fe3O4 nanocomposites under different external magnetic fields are also performed to explore its bio-applications. Finite element method (FEM) is used to simulate the local electromagnetic field distribution in Ag-Fe3O4 nanocomposites, revealing the SERS enhanced mechanism is determined mainly by the near field enhanced electromagnetic field. Due to its tunable and enhanced properties, Ag-Fe3O4 nanocomposites are expected to be promising SERS substrates for chemical and biological sensing applications.

  10. Hydrogen-storage properties of solid-solution alloys of immiscible neighboring elements with Pd.

    PubMed

    Kusada, Kohei; Yamauchi, Miho; Kobayashi, Hirokazu; Kitagawa, Hiroshi; Kubota, Yoshiki

    2010-11-17

    Rh and Ag are the elements neighboring Pd, which is well known as a hydrogen-storage metal. Although Rh and Ag do not possess hydrogen-storage properties, can Ag-Rh alloys actually store hydrogen? Ag-Rh solid-solution alloys have not been explored in the past because they do not mix with each other at the atomic level, even in the liquid phase. We have used the chemical reduction method to obtain such Ag-Rh alloys, and XRD and STEM-EDX give clear evidence that the alloys mixed at the atomic level. From the measurements of hydrogen pressure-composition isotherms and solid-state (2)H NMR, we have revealed that Ag-Rh solid-solution alloys absorb hydrogen, and the total amount of hydrogen absorbed reached a maximum at the ratio of Ag:Rh = 50:50, where the electronic structure is expected to be similar to that of Pd.

  11. Immiscible separation of metalliferous Fe/ Ti-oxide melts from fractionating alkali basalt: P-T-fO2 conditions and two-liquid elemental partitioning

    NASA Astrophysics Data System (ADS)

    Hurai, Vratislav; Simon, Klaus; Wiechert, Uwe; Hoefs, Jochen; Konečný, Patrik; Huraiová, Monika; Pironon, Jacques; Lipka, Jozef

    Globules of iron-dominated (59-69 wt% FeOtot) and titanium-dominated (43.5 wt% TiO2) oxide melts have been detected in igneous xenoliths from Pliocene-to-Pleistocene alkali basalts of the Western Carpathians. Fluid inclusion and mineral composition data indicate immiscible separation of the high-iron-oxide melt (HIM) at magmatic temperatures. The HIM separation occurred during clinopyroxene (augite) accumulation in an alkali trachybasalt and continued during crystallization of amphibole (kaersutite) and K-feldspar (anorthoclase), the latter coexisting with trachyte and alkalic rhyolite residual melts. Some HIM was also expelled from sub-alkalic rhyolite (70-77% SiO2), coexisting with An27-45 plagioclase and quartz in granitic (tonalite-trondhjemite) xenoliths. Oxygen fugacities during HIM separation range from -1.4to +0.6log units around the QFM buffer. A close genetic relationship between HIM-hosted xenoliths and mantle-derived basaltic magma is documented by mineral 18O values ranging from 4.9 to 5.9‰ V-SMOW. δD values of gabbroic kaersutite between -61 and -86‰ V-SMOW are in agreement with a presumed primary magmatic water source. Most trace elements, except Li, Rb and Cs, have preferentially partitioned into the HIM. The HIM/Si-melt partition coefficients for transition elements (Sc, V, Cr, Co, Ni) and base metals (Zn, Cu, Mo) are between 2-160, resulting in extreme enrichment in the HIM. La and Ce also concentrate in the silicic melt, whereas Tb-Tm in the HIM. Hence, the immiscible separation causes REE fractionation and produces residual silicic melt enriched in LREE and depleted in HREE. The weak fractionation among Tb-Tm and Yb, Lu can be attributed to recurrent extraction of the HIM from the magmatic system, while flat HREE chondrite-normalized patterns are interpreted to indicate no or little loss of the HIM.

  12. Late-magmatic immiscibility during batholith formation: assessment of B isotopes and trace elements in tourmaline from the Land's End granite, SW England

    NASA Astrophysics Data System (ADS)

    Drivenes, Kristian; Larsen, Rune B.; Müller, Axel; Sørensen, Bjørn E.; Wiedenbeck, Michael; Raanes, Morten P.

    2015-06-01

    Quartz-tourmaline orbicules are unevenly distributed in the roof segment of the Land's End granite, SW England. This study shows that the orbicules formed from an immiscible hydrous borosilicate melt produced during the late stages of crystallization, and differentiates tourmaline formed by dominantly magmatic and dominantly hydrothermal processes. Trace elements and boron isotope fractionation can be tracked in tourmaline, and create a timeline for crystallization. Tourmaline from the granite matrix has higher V, Cr and Mg content and is isotopically heavier than the later crystallizing inner orbicule tourmaline. Overgrowths of blue tourmaline, occurring together with quartz showing hydrothermal cathodoluminescence textures, crystallized from an aqueous fluid during the very last crystallization, and are significantly higher in Sr and Sn, and isotopically heavier. Tourmaline associated with Sn mineralization is also high in Sr and Sn, but has boron isotopic compositions close to that of the magmatic tourmaline, and is not formed by the same fluids responsible for the blue overgrowths. The ore-forming fluids precipitating tourmaline and cassiterite are likely derived from the same magma source as the granite, but exsolved deeper in the magma chamber, and at a later stage than orbicule formation. Tourmaline from massive quartz-tourmaline rocks is concentrically zoned, with major and trace element compositions indicating crystallization from a similar melt as for the orbicules, but shows a more evolved signature.

  13. Ag-Fe2O3 nanocomposites with enhanced catalytic activity for reduction of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Liu, Shiben; Chen, Yingjie; Dong, Lifeng

    2016-07-01

    Hybrid nanostructures can be multifunctional and even possess enhanced properties. Ag-Fe2O3 nanocomposites and Ag nanoparticles (NPs) were fabricated and applied to catalyze the reduction of 4-nitrophenol. Compared with Ag NPs, Ag-Fe2O3 nanocomposites demonstrated enhanced catalytic activities. Furthermore, due to their magnetic properties, Ag-Fe2O3 nanocomposites could be easily separated from the reaction mixture and recycled through an external magnetic field. These findings will help us design hybrid nanostructures with catalytic activity and explore other potential applications of magnetic nanocomposites.

  14. Transformation of Ag nanowires into semiconducting AgFeS2 nanowires.

    PubMed

    Sciacca, Beniamino; Yalcin, Anil O; Garnett, Erik C

    2015-04-08

    We report on the synthesis of semiconducting AgFeS2 nanowires, obtained from the conversion of Ag nanowires. The study of the conversion process shows that the formation of Ag2S nanowires, as an intermediate step, precedes the conversion into AgFeS2 nanowires. The chemical properties of AgFeS2 nanowires were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy at intermediate steps of the conversion process and show that the temperature at which the reaction takes place is critical to obtaining nanowires as opposed to nanotubes. Optical measurements on nanowire ensembles confirm the semiconducting nature of AgFeS2, with a direct band gap of 0.88 eV.

  15. Diffusion in Immiscible Melts

    NASA Technical Reports Server (NTRS)

    Pond, R. B.

    1985-01-01

    The objective of this program is to measure the diffusion coefficients for molten Pb in Zn in the immiscible liquid-phase region. Diffusion couples of pure Pb and Zn were prepared using a shear cell. These have been placed in graphite crucibles and encapsulated in stainless steel cartridges and are awaiting the next Materials Experiment Assembly (MEA) flight opportunity. In flight, one couple will be soaked for 40 minutes at 440 deg C (just above the monotectic temperature) and the second couple will be soaked for 40 minutes 820 deg C (just above the consolute temperature). After the soak both samples will be rapidly quenched by flowing He to minimize redistribution of the immiscible phases. Post flight compositional analysis will be accomplished using X-ray fluorescence in the scanning electron microscopy.

  16. Evaluation of the antibacterial activity of Ag/Fe3O4 nanocomposites synthesized using starch.

    PubMed

    Ghaseminezhad, Seyedeh Masumeh; Shojaosadati, Seyed Abbas

    2016-06-25

    Ag/Fe3O4 nanocomposites were successfully synthesized by a facile and cost-effective method using starch. Starch acts as both a biocompatible capping agent for Fe3O4 nanoparticles and a reducing agent for the reduction of silver ions in an alkaline medium. Samples were characterized using several analytical techniques including field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and Fourier-transform infrared (FT-IR) spectroscopy. The vibrating sample magnetometer revealed that the nanocomposites were superparamagnetic. The Ag/Fe3O4 nanocomposites demonstrated a high-antibacterial activity against Escherichia coli as evaluated by means of minimum inhibitory concentration. The characteristics and antibacterial activity of the nanocomposites were significantly influenced by the concentration of silver nitrate and pH.

  17. Fabrication of AgFeO2/g-C3N4 nanocatalyst with enhanced and stable photocatalytic performance

    NASA Astrophysics Data System (ADS)

    Tang, Dandan; Zhang, Gaoke

    2017-01-01

    This work reported a novel AgFeO2/g-C3N4 composite with enhanced photocatalytic activity, which was fabricated by a simple precipitation method. The g-C3N4 sheets with thickness of 2•4 nm were successfully loaded on the surface of the AgFeO2 particles. As compared to pure AgFeO2 and pure g-C3N4, the as-prepared AgFeO2/g-C3N4 photocatalysts exhibited superior absorption in the visible-light region and displayed promising visible-light photocatalytic performance in the degradation of organic contaminations both in water and in air. About 94% of Acid red G (ARG) can be degraded by the optimized AgFeO2/g-C3N4 sample, which is ∱/47.5 and ∱/410.7 times higher than that by pure AgFeO2 and pure g-C3N4, respectively. Meanwhile, it can also effectively degrade ∱/487% of gaseous formaldehyde to CO2 within 9 h. The enhanced photocatalytic property and stability of the AgFeO2/g-C3N4 composite can be attributed to its specific nanostructure, effective electron-hole separation and the formation of Z-scheme heterostructure between AgFeO2 and g-C3N4. This work could provide new and helpful insights into the photocatalytic application of Ag-based delafossite materials.

  18. Bifunctional Ag/Fe/N/C Catalysts for Enhancing Oxygen Reduction via Cathodic Biofilm Inhibition in Microbial Fuel Cells.

    PubMed

    Dai, Ying; Chan, Yingzi; Jiang, Baojiang; Wang, Lei; Zou, Jinlong; Pan, Kai; Fu, Honggang

    2016-03-23

    Limitation of the oxygen reduction reaction (ORR) in single-chamber microbial fuel cells (SC-MFCs) is considered an important hurdle in achieving their practical application. The cathodic catalysts faced with a liquid phase are easily primed with the electrolyte, which provides more surface area for bacterial overgrowth, resulting in the difficulty in transporting protons to active sites. Ag/Fe/N/C composites prepared from Ag and Fe-chelated melamine are used as antibacterial ORR catalysts for SC-MFCs. The structure-activity correlations for Ag/Fe/N/C are investigated by tuning the carbonization temperature (600-900 °C) to clarify how the active-constituents of Ag/Fe and N-species influence the antibacterial and ORR activities. A maximum power density of 1791 mW m(-2) is obtained by Ag/Fe/N/C (630 °C), which is far higher than that of Pt/C (1192 mW m(-2)), only having a decline of 16.14% after 90 days of running. The Fe-bonded N and the cooperation of pyridinic N and pyrrolic N in Ag/Fe/N/C contribute equally to the highly catalytic activity toward ORR. The ·OH or O2(-) species originating from the catalysis of O2 can suppress the biofilm growth on Ag/Fe/N/C cathodes. The synergistic effects between the Ag/Fe heterojunction and N-species substantially contribute to the high power output and Coulombic efficiency of Ag/Fe/N/C catalysts. These new antibacterial ORR catalysts show promise for application in MFCs.

  19. Solid solution alloy nanoparticles of immiscible Pd and Ru elements neighboring on Rh: changeover of the thermodynamic behavior for hydrogen storage and enhanced CO-oxidizing ability.

    PubMed

    Kusada, Kohei; Kobayashi, Hirokazu; Ikeda, Ryuichi; Kubota, Yoshiki; Takata, Masaki; Toh, Shoichi; Yamamoto, Tomokazu; Matsumura, Syo; Sumi, Naoya; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kitagawa, Hiroshi

    2014-02-05

    Pd(x)Ru(1-x) solid solution alloy nanoparticles were successfully synthesized over the whole composition range through a chemical reduction method, although Ru and Pd are immiscible at the atomic level in the bulk state. From the XRD measurement, it was found that the dominant structure of Pd(x)Ru(1-x) changes from fcc to hcp with increasing Ru content. The structures of Pd(x)Ru(1-x) nanoparticles in the Pd composition range of 30-70% consisted of both solid solution fcc and hcp structures, and both phases coexist in a single particle. In addition, the reaction of hydrogen with the Pd(x)Ru(1-x) nanoparticles changed from exothermic to endothermic as the Ru content increased. Furthermore, the prepared Pd(x)Ru(1-x) nanoparticles demonstrated enhanced CO-oxidizing catalytic activity; Pd0.5Ru0.5 nanoparticles exhibit the highest catalytic activity. This activity is much higher than that of the practically used CO-oxidizing catalyst Ru and that of the neighboring Rh, between Ru and Pd.

  20. Studies on immiscible alloys

    NASA Technical Reports Server (NTRS)

    Otto, G.

    1976-01-01

    To illustrate the behavior of immiscible liquids of different densities in zero-gravity and to determine the rate of coalescence like droplets, a demonstration experiment was performed on the Skylab 4 mission. Dispersions of oil-in-water and of water-in-oil were prepared by the astronauts and their appearance photographed over a time span of 10 hours. The experiment indicated that all emulsions were stable over this period and that the coalescent rate was at least 3 times 10 to the 5th power times smaller on Skylab than on earth. The recorded melting of a cylindrical piece of ice on Skylab 3 is used to study the mode of heat transfer for the latent heat of melting in low-gravity.

  1. Rapid degradation of hexachlorobenzene by micron Ag/Fe bimetal particles.

    PubMed

    Nie, Xiaoqin; Liu, Jianguo; Zeng, Xianwei; Yue, Dongbei

    2013-03-01

    The feasibility of the rapid degradation of hexachlorobenzene (HCB) by micron-size silver (Ag)/iron (Fe) particles was investigated. Ag/Fe particles with different ratios (0, 0.05%, 0.09%, 0.20%, and 0.45%) were prepared by electroless silver plating on 300 mesh Fe powder, and were used to degrade HCB at different pH values and temperatures. The dechlorination ability of Fe greatly increased with small Ag addition, whereas too much added Ag would cover the Fe surface and reduce the effective reaction surface, thereby decreasing the extent of dechlorination. The optimal Ag/Fe ratio was 0.09%. Tafel polarization curves showed that HCB was rapidly degraded at neutral or acidic pH, whereas low pH levels severely intensified H2 production, which consumed the reducing electrons needed for the HCB degradation. HCB degradation was more sensitive to temperature than pH. The rate constant of HCB dechlorination was 0.452 min- at 85 degrees C, 50 times higher than that at 31 degrees C. HCB was degraded in a successive dechlorination pathway, yielding the main products 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene within 2 hr.

  2. Spiral-spin-driven ferroelectricity in a multiferroic delafossite AgFeO2.

    PubMed

    Terada, Noriki; Khalyavin, Dmitry D; Manuel, Pascal; Tsujimoto, Yoshihiro; Knight, Kevin; Radaelli, Paolo G; Suzuki, Hiroyuki S; Kitazawa, Hideaki

    2012-08-31

    We have performed dielectric measurements and neutron diffraction experiments on the delafossite AgFeO2. A ferroelectric polarization P is approximately equal to 300 μC/m2 was observed in a powder sample, below 9 K. The neutron diffraction experiment demonstrated successive magnetostructural phase transitions at T(N1)=15 K and T(N2)=9 K. The magnetic structure for 9 K≤T≤15 K is a spin-density wave with a temperature dependent incommensurate modulation k=(-1, q, 1/2), q is approximately equal to 0.384. Below 9 K, the magnetic structure turns into elliptical cycloid with the incommensurate propagation vector k=(-1/2,q,1/2), q is approximately equal to 0.2026 Based on the deduced magnetic point-group symmetry m1' of the low-temperature polar phase, we conclude that the ferroelectric polarization in AgFeO2 is perpendicular to the monoclinic b axis and is driven by the inverse Dzyaloshinskii-Moriya effect with two orthogonal components p1 is proportional to r(ij)×(S(i)×S(j)) and p2 is proportional to S(i)×S(j).

  3. Ag/FeCo/Ag core/shell/shell magnetic nanoparticles with plasmonic imaging capability.

    PubMed

    Takahashi, Mari; Mohan, Priyank; Nakade, Akiko; Higashimine, Koichi; Mott, Derrick; Hamada, Tsutomu; Matsumura, Kazuaki; Taguchi, Tomohiko; Maenosono, Shinya

    2015-02-24

    Magnetic nanoparticles (NPs) have been used to separate various species such as bacteria, cells, and proteins. In this study, we synthesized Ag/FeCo/Ag core/shell/shell NPs designed for magnetic separation of subcellular components like intracellular vesicles. A benefit of these NPs is that their silver metal content allows plasmon scattering to be used as a tool to observe detection by the NPs easily and semipermanently. Therefore, these NPs are considered a potential alternative to existing fluorescent probes like dye molecules and colloidal quantum dots. In addition, the Ag core inside the NPs suppresses the oxidation of FeCo because of electron transfer from the Ag core to the FeCo shell, even though FeCo is typically susceptible to oxidation. The surfaces of the Ag/FeCo/Ag NPs were functionalized with ε-poly-L-lysine-based hydrophilic polymers to make them water-soluble and biocompatible. The imaging capability of the polymer-functionalized NPs induced by plasmon scattering from the Ag core was investigated. The response of the NPs to a magnetic field using liposomes as platforms and applying a magnetic field during observation by confocal laser scanning microscopy was assessed. The results of the magnetophoresis experiments of liposomes allowed us to calculate the magnetic force to which each liposome was subjected.

  4. The nature and barium partitioning between immiscible melts - A comparison of experimental and natural systems with reference to lunar granite petrogenesis

    NASA Technical Reports Server (NTRS)

    Neal, C. R.; Taylor, L. A.

    1989-01-01

    Elemental partitioning between immiscible melts has been studied using experimental liquid-liquid Kds and those determined by analysis of immiscible glasses in basalt mesostases in order to investigate lunar granite petrogenesis. Experimental data show that Ba is partitioned into the basic immiscible melt, while probe analysis results show that Ba is partitioned into the granitic immiscible melt. It is concluded that lunar granite of significant size can only occur in a plutonic or deep hypabyssal environment.

  5. Physical properties of immiscible polymers

    NASA Technical Reports Server (NTRS)

    Harris, J. Milton

    1987-01-01

    The demixing of immiscible polymers in low gravity is discussed. Applications of knowledge gained in this research will provide a better understanding of the role of phase segregation in determining the properties of polymer blends made from immiscible polymers. Knowledge will also be gained regarding the purification of biological materials by partitioning between the two liquid phases formed by solution of the polymers polyethylene glycol and dextran in water. Testing of new apparatus for space flight, extension of affinity phase partitioning, refinement of polymer chemistry, and demixing of isopycnic polymer phases in a one gravity environment are discussed.

  6. Novel AgCl/Ag/AgFeO2 Z-scheme heterostructure photocatalyst with enhanced photocatalytic and stability under visible light

    NASA Astrophysics Data System (ADS)

    Song, Zhe; He, Yiqiang

    2017-10-01

    A new AgCl/Ag/AgFeO2 composite was synthesized for the first time via a simple precipitation method. The very detailed characterizations were enforced in photocatalytic activity and stability. The photocatalytic performance was studied by the degradation of the rhodamine B (RhB, a cationic dye) under visible irradiation. The as-prepared AgCl/Ag/AgFeO2 photocatalyst exhibited excellent photocatalytic activity and stability under the visible light region compared to pure AgCl and AgFeO2. About 97.47% of RhB can be removed in 60 min by the optimized AgCl/Ag/AgFeO2 composite, which was ∼2.26 and ∼10.83 times as fast as that pure AgCl and pure AgFeO2. After three cycles visible light irradiation experiments found that degradation rate of RhB reached 76.35%, which was still higher than pure AgCl and AgFeO2. The obviously enhanced photocatalytic activity of AgCl/Ag/AgFeO2 composites can be attributed to the efficient separation of electron-hole pairs of the Z-scheme heterostructure between AgCl, Ag and AgFeO2. In this study, we also found the superoxide radicals (rad O2-) was considered to be the dominant active radical in the degradation of dye.

  7. Synthesis and characterization of noble metal nanocomposites: Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO for better photocatalytic activity under visible light irradiation

    NASA Astrophysics Data System (ADS)

    Tju, H.; Prakoso, S. P.; Taufik, A.; Saleh, R.

    2017-04-01

    Nobel metal such as silver (Ag) nanoparticles have been proven could enhance photocatalytic activity under visible light irradiation and prevent recombination of electron and hole. Fe3O4/ZnO and Fe3O4/CuO/ZnO has been investigated in our previous study. So in this work, a magnetic Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO nanocomposites were successfully synthesized using sol-gel method. The as-synthesized products were characterized by X-ray diffraction and ultraviolet-visible (UV-Vis) spectroscopy. The results showed that the nanocomposites were the combination of the desired nanoparticles. From the UV-Vis absorption spectra, we found the surface plasmon resonance (SPR) to be around ~440 nm. Under visible light irradiation, the Ag/Fe3O4/ZnO and Ag/Fe3O4/CuO/ZnO nanocomposites exhibited much higher photocatalytic activity than the Fe3O4/ZnO and Fe3O4/CuO/ZnO. The effect of catalyst dosage and initial concentration of methylene blue (MB) were also tested. To understand the mechanism in photocatalytic activity, several scavengers were tested. The reusability study suggested that the prepared nanocomposites can still maintain the degradation efficiency after four cycles, showing great potential for water purification.

  8. Thermodynamic estimation of minor element distribution between immiscible liquids in Fe-Cu-based metal phase generated in melting treatment of municipal solid wastes

    SciTech Connect

    Lu, X.; Nakajima, K.; Sakanakura, H.; Matsubae, K.; Bai, H.; Nagasaka, T.

    2012-06-15

    Graphical abstract: Display Omitted Highlights: Black-Right-Pointing-Pointer Two liquids separation of metal occurs in the melting of municipal solid waste. Black-Right-Pointing-Pointer The distribution of PGMs etc. between two liquid metal phases is studied. Black-Right-Pointing-Pointer Quite simple thermodynamic model is applied to predict the distribution ratio. Black-Right-Pointing-Pointer Au and Ag originated from WEEE are found to be concentrated into Cu-rich phase. - Abstract: Waste electrical and electronic equipment (WEEE) has become an important target in managing material cycles from the viewpoint of not only waste management and control of environmental pollution but also resource conservation. This study investigated the distribution tendency of trace elements in municipal solid waste (MSW) or incinerator ash, including valuable non-ferrous metals (Ni, Co, Cr, Mn, Mo, Ti, V, W, Zr), precious group metals (PGMs) originated from WEEE (Ag, Au, Pd, Pt), and others (Al, B, Pb, Si), between Fe-rich and Cu-rich metal phases by means of simple thermodynamic calculations. Most of the typical alloying elements for steel (Co, Cr, Mo, Nb, Ni, Si, Ti, V, and W) and Rh were preferentially distributed into the Fe-rich phase. PGMs, such as Au, Ag, and Pd, were enriched in the Cu-rich phase, whereas Pt was almost equally distributed into both phases. Since the primary metallurgical processing of Cu is followed by an electrolysis for refining, and since PGMs in crude copper have been industrially recovered from the resulting anode slime, our results indicated that Ag, Au, and Pd could be effectively recovered from MSW if the Cu-rich phase could be selectively collected.

  9. Excitation of plasmons in Ag/Fe/W structure by spin-polarized electrons

    SciTech Connect

    Samarin, Sergey N.; Kostylev, Mikhail; Williams, J. F.; Artamonov, Oleg M.; Baraban, Alexander P.; Guagliardo, Paul

    2015-09-07

    Using Spin-polarized Electron-Energy Loss Spectroscopy (SPEELS), the plasmon excitations were probed in a few atomic layers thick Ag film deposited on an Fe layer or on a single crystal of W(110). The measurements were performed at two specular geometries with either a 25° or 72° angle of incidence. On a clean Fe layer (10 atomic layers thick), Stoner excitation asymmetry was observed, as expected. Deposition of a silver film on top of the Fe layer dramatically changed the asymmetry of the SPEELS spectra. The spin-effect depends on the kinematics of the scattering: angles of incidence and detection. The spin-dependence of the plasmon excitations in the silver film on the W(110) surface and on the ferromagnetic Fe film is suggested to arise from the spin-active Ag/W or Ag/Fe interfaces.

  10. Facile synthesis of nano silver ferrite (AgFeO₂) modified with chitosan applied for biothiol separation.

    PubMed

    Abdelhamid, Hani Nasser; Wu, Hui-Fen

    2014-12-01

    Silver iron oxide nanoparticles (AgFeO2 NPs) with narrow size distribution have been synthesized, characterized and was applied for biothiols separation. AgFeO2 and AgFeO2 modified chitosan (AgFeO2@CTS NPs) were synthesized using a hydrothermal method and then characterized by electron microscopy (transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX)), X-ray diffraction (XRD), and Fourier transform infrared (FTIR). Different biological thiols (dithiothreitol, glutathione, thiabendazole, and sulfamethizole) were investigated and characterized using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) and surface assisted laser desorption/ionization mass spectrometry (SALDI-MS). The new material displays dual functionality; 1) for separation and 2) can be served as the matrices for SALDI-MS. Data showed a clear background in the case of nanomaterials compared to conventional matrices (mefenamic acid and 2,5-dihydroxybenzoic acid (DHB) for MALDI-MS). Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Highly efficient and porous TiO2-coated Ag@Fe3O4@C-Au microspheres for degradation of organic pollutants

    NASA Astrophysics Data System (ADS)

    Shen, Mao; Chen, Suqing; Jia, Wenping; Fan, Guodong; Jin, Yanxian; Liang, Huading

    2016-12-01

    In this paper, we reported a novel hierarchical porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres with a highly photocatalytic activity and magnetically separable properties. The synthesis method is included of a Fe3O4 magnetic embedded Ag core (Ag@Fe3O4), an interlayer of carbon modified by PEI to form sufficient amounts of amine functional groups (Ag@Fe3O4@C-PEI), the grafting of Au nanoparticles on the surface of Ag@Fe3O4@C-PEI (Ag@Fe3O4@C-Au), and an ordered porous TiO2 structured shell. As an example of the applications, the photocatalytic activities of the samples were investigated by the reduction of Rhodamine B (RhB) under visible-light irradiation. The results show that the porous Ag@Fe3O4@C-Au@TiO2 core@shell microspheres display higher adsorption and photocatalytic activities compared to the pure porous TiO2 and Ag@Fe3O4@C@TiO2 microspheres, which are attributed to the local surface plasmon resonance (LSPR) by the Ag and Au nanoparticles and the high specific surface area.

  12. Ag[Fe(CO)5]2(+) : a bare silver complex with Fe(CO)5 as a ligand.

    PubMed

    Malinowski, Przemysław J; Krossing, Ingo

    2014-12-01

    Attempts to prepare Fe(CO)5 (+) from Ag[Al(OR(F) )4 ] (R(F) =C(CF3 )3 ) and Fe(CO)5 in CH2 Cl2 yielded the first complex of a neutral metal carbonyl bound to a simple metal cation. The Ag[Fe(CO)5 ]2 (+) cation consists of two Fe(CO)5 molecules coordinating Ag(+) in an almost linear fashion. The ν(CO) modes are blue-shifted compared to Fe(CO)5 , with one band above 2143 cm(-1) indicating that back-bonding is heavily decreased in the Ag[Fe(CO)5 ]2 (+) cation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Facile one-step synthesis of Ag@Fe3O4 core-shell nanospheres for reproducible SERS substrates

    NASA Astrophysics Data System (ADS)

    Sun, Lijuan; He, Jiang; An, Songsong; Zhang, Junwei; Ren, Dong

    2013-08-01

    A facile approach has been developed to synthesize Ag@Fe3O4 core-shell nanospheres, in which the Ag nanoparticle core was well wrapped by a permeable Fe3O4 shell. An in situ reduction of AgNO3 and Fe(NO3)3 was the basis of this one-step method with ethylene glycol as the reducing agent. The as-obtained Ag@Fe3O4 nanospheres were a highly efficient surface-enhanced Raman scattering (SERS) substrate; high reproducibility, stability, and reusability were obtained by employing 4-aminothiophenol (4-ATP) and rhodamine 6G (R6G) as the Raman probe molecules. It was revealed that the SERS signals of 4-ATP and R6G on the Ag@Fe3O4 nanospheres were much stronger than those on the pure Ag nanoparticles, demonstrating that the magnetic enrichment procedures can improve SERS detection sensitivity efficiently. A highly efficient and recyclable SERS substrate was produced by the new model system that has potential applications in chemical and biomolecular assays.

  14. Factors Influence the Structural and Magnetic Properties of Ag-Fe3O4 Nanocomposites Synthesized by Reduction Method

    NASA Astrophysics Data System (ADS)

    Fajaroh, F.; Nazriati

    2017-05-01

    Silver nanoparticles integrated with a magnetic matrix such as Fe3O4 to form Ag-Fe3O4 nanocomposites show some advantages in their applications as an antibacterial agent and heterogeneous catalyst. This material can be synthesized by a combination of electrochemical and reduction methods supported by ultrasonic route. The purposes of this study are to synthesize the nanocomposites by reduction method and to study the effect of synthesis parameters on the structural and magnetic properties of the generated nanocomposites. This research consisted of three main stages. The first step was the electrochemical synthesis of magnetite nanoparticles using electro-oxidation of iron in water. Second, adsorption of Ag+ on the surface of Fe3O4 carried out by sonication of a mixture of AgNO3 solution and powder of Fe3O4 nanoparticles. The third stage was the reduction of Ag+ to Ag0 with glucose as reductant and NaOH as an accelerator, where it was conducted under a variation of AgNO3 mole ratios to glucose and NaOH concentration. The characterizations of Ag-Fe3O4 nanocomposites were performed using XRD and VSM. The results of the characterizations showed that Ag-Fe3O4 nanocomposites have been successfully synthesized. There was an optimum concentration of NaOH at pH (11) and mole ratio of AgNO3 to glucose (1 : 8) in the synthesis process producing the composite with the highest crystallinity.

  15. Coupled growth of immiscible alloys

    SciTech Connect

    Andrews, B.; Hayes, L.; Arikawa, Y.; O`Dell, S.; Cheney, A.

    1996-12-31

    This paper discusses the flight experiment Coupled Growth in Hypermonotectics scheduled to fly aboard the Life and Microgravity Spacelab mission during the Summer of 1996. The experiment is designed to directionally solidify samples in immiscible alloy systems in an attempt to obtain an improved understanding of the physics controlling the solidification process. This paper specifically addresses some of the unique difficulties concerning ampoule design for these experiments. As an example, an ampoule material must be utilized that is not wet by the minor immiscible liquid phase. In addition, a means must be provided to accommodate thermal contraction and solidification shrinkage during processing in order to avoid free surface formation on the melt. An attempt has also been made to control thermal end effects in order to obtain a relatively constant growth rate during processing. The final design results in an ampoule assembly that contains insulating segments, dummy samples, moving pistons and a high temperature spring assembly. The details of this design and the results of ground based testing will be discussed.

  16. Coupled growth in immiscible alloys

    NASA Astrophysics Data System (ADS)

    Andrews, J. Barry; Hayes, Larry C.; Arikawa, Y.; O'Dell, S.; Cheney, A.

    1996-07-01

    This paper discusses the flight experiment 'Coupled Growth in Hypermonotectics' schedules to fly aboard the life and microgravity spacelab mission during the summer of 1996. The experiment is designed to directionally solidify samples in immiscible alloy systems in an attempt to obtain an improved understanding of the physics controlling the solidification process. This paper specifically addresses some of the unique difficulties concerning ampoule design for these experiments. As an example, an ampoule material must be utilized that is not wet by the minor immiscible liquid phase. In addition, a means must be provided to accommodate thermal contraction and solidification shrinkage during processing in order to avoid free surface formation on the melt. An attempt has also been made to control thermal end effects in order to obtain a relatively constant growth rate during processing. The final design results in an ampoule assembly that contains insulating segments, dummy samples, moving pistons and a high temperature spring assembly. The details of this design and the results of ground based testing will be discussed.

  17. Structure and properties of α-AgFe 2(MoO 4) 3

    NASA Astrophysics Data System (ADS)

    Balsanova, L.; Mikhailova, D.; Senyshyn, A.; Trots, D.; Fuess, H.; Lottermoser, W.; Ehrenberg, H.

    2009-06-01

    Silver diiron tris(oxomolybdate), α-AgFe 2(MoO 4) 3, was synthesized in sealed silica tubes at 1050 K and is isostructural to α-NaFe 2(MoO 4) 3, determined by single-crystal X-ray diffraction (space group P-1, a = 6.9320(7) Å, b = 6.9266(6) Å, c = 10.9732(13) Å, α = 81.197(8)°, β = 83.456(9)°, γ = 81.352(8)° at 300 K, Z = 2). The crystal structure is built up from both monomers and edge-sharing dimers of [FeO 6]-octahedra, which are linked with each other by isolated [MoO 4]-tetrahedra to a three-dimensional network. Ag ions are situated on a site with four near oxygen neighbours. Thermal expansion is most pronounced along the c-axis, while the angle α decreases with increasing temperature. Antiferromagnetic ordering is indicated by a sharp maximum in the temperature dependence of magnetization at 21.5(5) K, and a magnetic moment of 5.36(1) μ B per Fe-ion was derived from the Curie constant in the paramagnetic region. The collinear antiferromagnetic structure with propagation vector k = (0,½,½) and an ordered magnetic moment of 4.62(9) μ B per Fe-ion were deduced from neutron powder diffraction data and give evidence for an underlying magnetic interaction mechanism, resulting in rather strong and long-ranged couplings. Mössbauer spectroscopy shows a change in the electronic configuration on the two distinct Fe sites between room temperature and 150 K, accompanied by an increase of the average Fe-O distance for one site and a shrinking one for the other as expected for charge ordering in a mixed valence compound with Fe(II) and Fe(III).

  18. Flow regimes during immiscible displacement

    DOE PAGES

    Armstrong, Ryan T.; Mcclure, James; Berrill, Mark A.; ...

    2017-02-01

    Fractional ow of immiscible phases occurs at the pore scale where grain surfaces and phases interfaces obstruct phase mobility. However, the larger scale behavior is described by a saturation-dependent phenomenological relationship called relative permeability. As a consequence, pore-scale parameters, such as phase topology and/ or geometry, and details of the flow regime cannot be directly related to Darcy-scale flow parameters. It is well understood that relative permeability is not a unique relationship of wetting-phase saturation and rather depends on the experimental conditions at which it is measured. Herein we use fast X-ray microcomputed tomography to image pore-scale phase arrangements duringmore » fractional flow and then forward simulate the flow regimes using the lattice-Boltzmann method to better understand the underlying pore-scale flow regimes and their influence on Darcy-scale parameters. We find that relative permeability is highly dependent on capillary number and that the Corey model fits the observed trends. At the pore scale, while phase topologies are continuously changing on the scale of individual pores, the Euler characteristic of the nonwetting phase (NWP) averaged over a sufficiently large field of view can describe the bulk topological characteristics; the Euler characteristic decreases with increasing capillary number resulting in an increase in relative permeability. Lastly, we quantify the fraction of NWP that flows through disconnected ganglion dynamics and demonstrate that this can be a significant fraction of the NWP flux for intermediate wetting-phase saturation. Furthermore, rate dependencies occur in our homogenous sample (without capillary end effect) and the underlying cause is attributed to ganglion flow that can significantly influence phase topology during the fractional flow of immiscible phases.« less

  19. Influence of biocompatible metal ions (Ag, Fe, Y) on the surface chemistry, corrosion behavior and cytocompatibility of Mg-1Ca alloy treated with MEVVA.

    PubMed

    Liu, Yang; Bian, Dong; Wu, Yuanhao; Li, Nan; Qiu, Kejin; Zheng, Yufeng; Han, Yong

    2015-09-01

    Mg-1Ca samples were implanted with biocompatible alloy ions Ag, Fe and Y respectively with a dose of 2×10(17)ionscm(-2) by metal vapor vacuum arc technique (MEVVA). The surface morphologies and surface chemistry were investigated by SEM, AES and XPS. Surface changes were observed after all three kinds of elemental ion implantation. The results revealed that the modified layer was composed of two sublayers, including an outer oxidized layer with mixture of oxides and an inner implanted layer, after Ag and Fe ion implantation. Y ion implantation induced an Mg/Ca-deficient outer oxidized layer and the distribution of Y along with depth was more homogeneous. Both electrochemical test and immersion test revealed accelerated corrosion rate of Ag-implanted Mg-1Ca and Fe-implanted Mg-1Ca, whereas Y ion implantation showed a short period of protection since enhanced corrosion resistance was obtained by electrochemical test, but accelerated corrosion rate was found by long period immersion test. Indirect cytotoxicity assay indicated good cytocompatibility of Y-implanted Mg-1Ca. Moreover, the corresponding corrosion mechanisms involving implanting ions into magnesium alloys were proposed, which might provide guidance for further application of plasma ion implantation to biodegradable Mg alloys.

  20. Thermal Annealing Effect on Structural, Morphological, and Sensor Performance of PANI-Ag-Fe Based Electrochemical E. coli Sensor for Environmental Monitoring.

    PubMed

    Mohammad Naim, Norshafadzila; Abdullah, H; Umar, Akrajas Ali; Abdul Hamid, Aidil; Shaari, Sahbudin

    2015-01-01

    PANI-Ag-Fe nanocomposite thin films based electrochemical E. coli sensor was developed with thermal annealing. PANI-Ag-Fe nanocomposite thin films were prepared by oxidative polymerization of aniline and the reduction process of Ag-Fe bimetallic compound with the presence of nitric acid and PVA. The films were deposited on glass substrate using spin-coating technique before they were annealed at 300 °C. The films were characterized using XRD, UV-Vis spectroscopy, and FESEM to study the structural and morphological properties. The electrochemical sensor performance was conducted using I-V measurement electrochemical impedance spectroscopy (EIS). The sensitivity upon the presence of E. coli was measured in clean water and E. coli solution. From XRD analysis, the crystallite sizes were found to become larger for the samples after annealing. UV-Vis absorption bands for samples before and after annealing show maximum absorbance peaks at around 422 nm-424 nm and 426 nm-464 nm, respectively. FESEM images show the diameter size for nanospherical Ag-Fe alloy particles increases after annealing. The sensor performance of PANI-Ag-Fe nanocomposite thin films upon E. coli cells in liquid medium indicates the sensitivity increases after annealing.

  1. Compact Ag@Fe3O4 Core-shell Nanoparticles by Means of Single-step Thermal Decomposition Reaction

    PubMed Central

    Brollo, Maria Eugênia F.; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J. A.; Pirota, Kleber R.; Knobel, Marcelo

    2014-01-01

    A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine. PMID:25354532

  2. Compact Ag@Fe3O4 Core-shell Nanoparticles by Means of Single-step Thermal Decomposition Reaction

    NASA Astrophysics Data System (ADS)

    Brollo, Maria Eugênia F.; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J. A.; Pirota, Kleber R.; Knobel, Marcelo

    2014-10-01

    A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine.

  3. Compact Ag@Fe3O4 core-shell nanoparticles by means of single-step thermal decomposition reaction.

    PubMed

    Brollo, Maria Eugênia F; López-Ruiz, Román; Muraca, Diego; Figueroa, Santiago J A; Pirota, Kleber R; Knobel, Marcelo

    2014-10-30

    A temperature pause introduced in a simple single-step thermal decomposition of iron, with the presence of silver seeds formed in the same reaction mixture, gives rise to novel compact heterostructures: brick-like Ag@Fe3O4 core-shell nanoparticles. This novel method is relatively easy to implement, and could contribute to overcome the challenge of obtaining a multifunctional heteroparticle in which a noble metal is surrounded by magnetite. Structural analyses of the samples show 4 nm silver nanoparticles wrapped within compact cubic external structures of Fe oxide, with curious rectangular shape. The magnetic properties indicate a near superparamagnetic like behavior with a weak hysteresis at room temperature. The value of the anisotropy involved makes these particles candidates to potential applications in nanomedicine.

  4. Electrified Microscopic and Conventional Interfaces between Two Immiscible Electrolyte Solutions

    DTIC Science & Technology

    1991-06-24

    2 INTRODUCTION TO ELECTRIFIED LIQUID / LIQUID INTERFACES Interfaces between two immiscible solutions containing ionic species are of interest to a wide...if necessary and identify by block number) PELD I GPOUP SUB GROUP MICRODOMAINS, MICELES, LIQUID - LIQUID ELECTROCHEMISTRY, IMMISCIBLE ELECTROLYTES...between immiscible phases bridges the field of heterogeneous electrode electrochemistry and that of homogeneous solution chemistry. Early work on liquid

  5. Multilayer fluid dynamics of immiscible liquids

    NASA Technical Reports Server (NTRS)

    Koster, Jean N.

    1994-01-01

    A comprehensive analytical, numerical and experimental study of convective flow in multilayer immiscible liquids has been performed. Studies include transparent high Prandtl number of liquid as well as opaque low Prandtl metallic melts. A new radioscopic flow visualization has been developed for the latter studies.

  6. Can Nanorods Emulsify Immiscible Polymer Blends?

    NASA Astrophysics Data System (ADS)

    Hore, Michael J. A.

    2005-03-01

    The addition of nanoscale rods to immiscible binary polymer blends has a pronounced effect on the dynamics of phase separation. The results of computer simulations of the Dissipative Particle Dynamics (DPD) model in three dimensions (3D) indicate that when nanorods prefer one of two components in an immiscible binary polymer blend, the rate of phase separation decreases when the volume fraction of nanorods is increased, or as the aspect ratio (L/D) of the rods is increased. Interestingly, anisotropic nanoparticles have a much more pronounced effect on phase separation dynamics in the system when compared to the effects of spherical nanoparticles, which, generically, do not alter the characteristics of the kinetics in the system. In particular, it may be the case that at high volume fractions -- or alternatively, low volume fractions and large aspect ratio of nanorods -- the system may undergo micro-phase separation only, indicating that the nanorods may be excellent emulsifying agents.

  7. Phase separation kinetics in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Ng, Lee H.; Sadoway, Donald R.

    1987-01-01

    The kinetics of phase separation in the succinonitrile-water system are being investigated. Experiments involve initial physical mixing of the two immiscible liquids at a temperature above the consolute, decreasing the temperature into the miscibility gap, followed by iamging of the resultant microstructure as it evolves with time. Refractive index differences allow documentation of the changing microstructures by noninvasive optical techniques without the need to quench the liquid structures for analysis.

  8. Phase separation kinetics in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Sadoway, D. R.

    1986-01-01

    The kinetics of phase separation in the succinonitrile-water system are being investigated. Experiments involve initial physical mixing of the two immiscible liquids at a temperature above the consolute, decreasing the temperature into the miscibility gap, followed by imaging of the resultant microstructure as it evolves with time. Refractive index differences allow documentation of the changing microstructures by noninvasive optical techniques without the need to quench the liquid structures for analysis.

  9. Measuring Interfacial Tension Between Immiscible Liquids

    NASA Technical Reports Server (NTRS)

    Rashidnia, Nasser; Balasubramaniam, R.; Delsignore, David M.

    1995-01-01

    Glass capillary tube technique measures interfacial tension between two immiscible liquids. Yields useful data over fairly wide range of interfacial tensions, both for pairs of liquids having equal densities and pairs of liquids having unequal densities. Data on interfacial tensions important in diverse industrial chemical applications, including enhanced extraction of oil; printing; processing foods; and manufacture of paper, emulsions, foams, aerosols, detergents, gel encapsulants, coating materials, fertilizers, pesticides, and cosmetics.

  10. Measuring Interfacial Tension Between Immiscible Liquids

    NASA Technical Reports Server (NTRS)

    Rashidnia, Nasser; Balasubramaniam, R.; Delsignore, David M.

    1995-01-01

    Glass capillary tube technique measures interfacial tension between two immiscible liquids. Yields useful data over fairly wide range of interfacial tensions, both for pairs of liquids having equal densities and pairs of liquids having unequal densities. Data on interfacial tensions important in diverse industrial chemical applications, including enhanced extraction of oil; printing; processing foods; and manufacture of paper, emulsions, foams, aerosols, detergents, gel encapsulants, coating materials, fertilizers, pesticides, and cosmetics.

  11. Compositional and kinetic controls on liquid immiscibility in ferrobasalt-rhyolite volcanic and plutonic series

    NASA Astrophysics Data System (ADS)

    Charlier, Bernard; Namur, Olivier; Grove, Timothy L.

    2013-07-01

    We present major element compositions of basalts and their differentiation products for some major tholeiitic series. The dry, low-pressure liquid lines of descent are shown to approach or intersect the experimentally-defined compositional space of silicate liquid immiscibility. Ferrobasalt-rhyolite unmixing along tholeiitic trends in both volcanic and plutonic environments is supported by worldwide occurrence of immiscible globules in the mesostasis of erupted basalts, unmixed melt inclusions in cumulus phases of major layered intrusions such as Skaergaard and Sept Iles, and oxide-rich ferrogabbros closely associated with plagiogranites in the lower oceanic crust. Liquid immiscibility is promoted by low-pressure, anhydrous fractional crystallization that drives the low Al2O3, high FeO liquids into the two-liquid field. Kinetic controls can be important in the development of two-liquid separation. The undercooling that occurs at the slow cooling rates of plutonic environments promotes early development of liquid immiscibility at higher temperature. In contrast rapid cooling in erupted lavas leads to large undercoolings and liquid immiscibility develops at significantly lower temperatures. Unmixing leads to the development of a compositional gap characterized by the absence of intermediate compositions, a feature of many tholeiitic provinces. The compositions of experimental unmixed silica-rich melts coincide with those of natural rhyolites and plagiogranites with high FeOtot and low Al2O3, suggesting the potential role of large-scale separation of immiscible Si-rich liquid in the petrogenesis of late-stage residual melts. No trace of the paired ferrobasaltic melt is found in volcanic environments because of its uneruptable characteristics. Instead, Fe-Ti ± P-rich gabbros are the cumulate products of immiscible Fe-rich melts in plutonic settings. The immiscibility process may be difficult to identify because both melts crystallize the same phases with the same

  12. Manipulation of the crystal structures and the consequent FMR behaviors in GaAs/Ag/Fe system with an ultrathin Fe seeding layer

    NASA Astrophysics Data System (ADS)

    Yu, C. C.; Teng, Y. H.; Tsai, C. S.; Yao, Y. D.; Liou, Y.

    2009-04-01

    The crystal structures, magnetic properties, and the behaviors of ferromagnetic resonance of the GaAs(001)/Fe/Ag/Fe multilayers with different thicknesses of the Fe seeding layer are investigated. For the first time, a transformation from polycrystal into nearly bcc (001) single-crystal structure is observed in the top Fe layer while the thickness of the Fe seeding layer increases. The frequency of ferromagnetic resonance in Fe/Ag/Fe multilayers can be tuned by varying the strength of the external magnetic field and the thickness of the Fe seeding layer. Also it can be well fitted by the resonance equation. The correlation between crystal structures and ferromagnetic resonance manifests itself.

  13. Numerical Modeling of Immiscible Organic Transport at the Hyde Park Landfill

    NASA Astrophysics Data System (ADS)

    Osborne, M.; Sykes, J.

    1986-01-01

    In this paper, a two-dimensional two-phase mathematical model based on Darcy's law and conservation of mass for each liquid is presented. The numerical model is based on a generalized method of weighted residuals in conjunction with the finite element method and linear quadrilateral isoparametric elements. To alleviate numerical problems associated with hyperbolic equations, upstream weighting of the spatial terms in the model has been incorporated. The theoretical and numerical accuracy of the model is verified by comparison of simulation results with those from an existing one-dimensional two-phase flow simulator. The finite element model is used to simulate the migration of an immiscible organic solvent in groundwater, from a chemical waste disposal site located north of Niagara Falls, New York. The effects of uncertainty regarding porous media heterogeneities and anisotropy are examined, and it is concluded that the extent of immiscible contaminant migration is greatly sensitive to these parameters.

  14. Ag/Fe3O4/ZrO2 Composite: Ternary Magnetically Separable UV-light-driven Photocatalyst for Removal Methylene Blue Dyes

    NASA Astrophysics Data System (ADS)

    Kristianto, Y.; Taufik, A.; Saleh, R.

    2017-05-01

    In this research, we demonstrate the preparation of ternary Ag/Fe3O4/ZrO2 composites as a novel magnetically separable UV-light-driven photocatalyst. The Fe3O4/ZrO2 composites were successfully synthesized by using two-step methods, that is, sol-gel followed by ultrasonic-assisted method. Furthermore, the Fe3O4/ZrO2 composites were coupled with silver through ultrasound-assisted method. The prepared samples were fairly characterized by using X-Ray Diffraction and UV-Vis DRS spectroscopy. The photocatalytic activity of this composite was tested to degrade methylene blue dyes under UV-light irradiation. The influence of catalyst dosage, initial concentration, and scavengers of active species were investigated and the results were discussed. Compared with Fe3O4/ZrO2 sample, the Ag/Fe3O4/ZrO2 composite with three weight ratio (5%, 15%, and 25%) of Ag to Fe3O4/ZrO2 display higher photocatalytic activity. Among three variations of the weight ratio of Ag to Fe3O4/ZrO2, 15% weight ratio of Ag in Ag/Fe3O4/ZrO2 exhibits the superior photocatalytic performance followed by weight ratio of 25% and 5%. Moreover, the composite was found to be a reusable catalyst.

  15. Size effect on alloying ability and phase stability of immiscible bimetallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Xiao, S.; Hu, W.; Luo, W.; Wu, Y.; Li, X.; Deng, H.

    2006-12-01

    In the present paper, the surface and size effects on the alloying ability and phase stability of immiscible alloy nanoparticles have been studied with calculating the heats of formation of Au-Pt alloy nanoparticles from the single element nanoparticles of their constituents (Au and Pt) with a simple thermodynamic model and an analytic embedded atom method. The results indicated that, besides the similar compositional dependence of heat of formation as in bulk alloys, the heat of formation of alloy nanoparticles exhibits notable size-dependence, and there exists a competition between size effect and compositional effect on the heat of formation of immiscible system. Contrary to the positive heat of formation for bulk-immiscible alloys, a negative heat of formation may be obtained for the alloy nanoparticles with a small size or dilute solute component, which implies a promotion of the alloying ability and phase stability of immiscible system on a nanoscale. The surface segregation results in an extension of the size range of particles with a negative heat of formation. The molecular dynamics simulations have indicated that the structurally and compositionally homogeneous AuPt nanoparticles tend to form a core-shell structure with temperature increasing.

  16. Boosted Hyperthermia Therapy by Combined AC Magnetic and Photothermal Exposures in Ag/Fe3O4 Nanoflowers.

    PubMed

    Das, R; Rinaldi-Montes, N; Alonso, J; Amghouz, Z; Garaio, E; García, J A; Gorria, P; Blanco, J A; Phan, M H; Srikanth, H

    2016-09-28

    Over the past two decades, magnetic hyperthermia and photothermal therapy are becoming very promising supplementary techniques to well-established cancer treatments such as radiotherapy and chemotherapy. These techniques have dramatically improved their ability to perform controlled treatments, relying on the procedure of delivering nanoscale objects into targeted tumor tissues, which can release therapeutic killing doses of heat either upon AC magnetic field exposure or laser irradiation. Although an intense research effort has been made in recent years to study, separately, magnetic hyperthermia using iron oxide nanoparticles and photothermal therapy based on gold or silver plasmonic nanostructures, the full potential of combining both techniques has not yet been systematically explored. Here we present a proof-of-principle experiment showing that designing multifunctional silver/magnetite (Ag/Fe3O4) nanoflowers acting as dual hyperthermia agents is an efficient route for enhancing their heating ability or specific absorption rate (SAR). Interestingly, the SAR of the nanoflowers is increased by at least 1 order of magnitude under the application of both an external magnetic field of 200 Oe and simultaneous laser irradiation. Furthermore, our results show that the synergistic exploitation of the magnetic and photothermal properties of the nanoflowers reduces the magnetic field and laser intensities that would be required in the case that both external stimuli were applied separately. This constitutes a key step toward optimizing the hyperthermia therapy through a combined multifunctional magnetic and photothermal treatment and improving our understanding of the therapeutic process to specific applications that will entail coordinated efforts in physics, engineering, biology, and medicine.

  17. Evaporative Mass Transfer Behavior of a Complex Immiscible Liquid

    PubMed Central

    McColl, Colleen M.; Johnson, Gwynn R.; Brusseau, Mark L.

    2010-01-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult’s law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

  18. Evaporative mass transfer behavior of a complex immiscible liquid.

    PubMed

    McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L

    2008-09-01

    A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.

  19. Magmatic (silicates/saline/sulfur-rich/CO2) immiscibility and zirconium and rare-earth element enrichment from alkaline magma chamber margins : Evidence from Ponza Island, Pontine Archipelago, Italy

    USGS Publications Warehouse

    Belkin, H.E.; de Vivo, B.; Lima, A.; Torok, K.

    1996-01-01

    incompatible elements.

  20. Low gravity containerless processing of immiscible gold rhodium alloys

    NASA Technical Reports Server (NTRS)

    Andrews, J. Barry

    1986-01-01

    Under normal one-g conditions immiscible alloys segregate extensively during solidification due to sedementation of the more dense of the immiscible liquid phases. However, under low-g conditions it should be possible to form a dispersion of the two immiscible liquids and maintain this dispersed structure during solidification. Immiscible (hypermonotectic) gold-rhodium alloys were processed in the Marshall Space Flight Center 105 meter drop tube in order to investigate the influence of low gravity, containerless solidification on their microstructure. Hypermonotectic alloys composed of 65 atomic % rhodium exhibited a tendency for the gold rich liquid to wet the outer surface of the containerless processed samples. This tendency led to extensive segregation in several cases. However, well dispersed microstructures consisting of 2 to 3 micron diameter rhodium-rich spheres in a gold-rich matrix were produced in 23.4 atomic % rhodium alloys. This is one of the best dispersions obtained in research on immiscible alloy-systems to data.

  1. Enhancement of giant magnetoresistance and oscillation by wave-vector filtering in Fe/Ag/Fe/InAs/Ag

    NASA Astrophysics Data System (ADS)

    Wang, Ziran; Victora, R. H.

    2016-12-01

    The performance of a giant magnetoresistance (GMR) heterostructure Fe/Ag/Fe/InAs/Ag(100) in the current-perpendicular-to-plane geometry is presented. Calculations are based on a realistic tight-banding model with full s p d bands and the recursive Green's function algorithm. Results show that the system's GMR can reach values above 1000%. This GMR enhancement mainly is a result of the wave-vector filtering effect imposed by the InAs layer, restricting conductance within a small region around the Γ point in the 2D Brillouin zone. Calculations also reveal that when the Fermi level sits in the InAs band gap, MR gradually saturates as a function of InAs thickness with a smooth plateau; whereas when the Fermi level is in the InAs conduction band and close to the band bottom, GMR exhibits an oscillatory behavior with a large period. GMR oscillations are also observed with respect to Ag thickness, with oscillation amplitude determined by the Fermi level position relative to the InAs conduction band edge. The oscillation periods in both cases can be well explained by the concept of quantum-well states, and are determined by the spanning vector of the Fermi surface belly of the material whose thickness is varied. The observed GMR oscillations are due to the quantum interference of conduction electrons near the Γ point. The GMR and area-resistance (RA) product profiles at a wide range of Fermi energy positions relative to InAs bands are also compared. Near the GMR peak (with GMR above 1000%) in the conduction band, RA product can be as low as 8.8 Ω μ m2 . This feature of large GMR but small RA product results from the wave-vector filtering effect of doped InAs, and it makes the structure under study distinct from conventional GMR systems (small GMR, small RA) or magnetic tunnel junctions (large GMR, large RA).

  2. On Theories for Reacting Immiscible Mixtures

    SciTech Connect

    Drumheller, D.S.

    1998-11-05

    On some small scale each constituent of an immiscible mixture occupies a separate region of space. Given sufficient time and computing power, we could solve the continuum field equations and boundary conditions for this het erogenous system. This usually represents an enormously difficult task that is well beyond today's computational ca- pabilities. Mixture theories approximate this complex heterogeneous formulation with a set of field equations for an equivalent homoge- neous mat erial. In this work, we compare the theory for immiscible mixtures by Drumheller and Bedford with the theory of Passman, Nunziato, and Walsh. We describe the conditions under which these theories reduce to an equivalent formulation, and we also investigate the differences in their microinertial descriptions. Two variables play special roles in both theories. They are t he true material density and the volume fraction. Here we use a kinematical approach based on two new variables-t he true deformation gradient and the distention gradient. We show how the true deformation gra- dient is connected to the true material density and, in the absence of chemical reactions, the volume fraction is the inverse of the deter- minant of the distention gradient. However, when chemical reactions occur, the distention gradient and the volume fraction are not directly connected. We ako present a mixture model for a granuIar expIosive. This model is based upon the work of Baer and Nunziato, but our theory differs from their work in that we Present a three-dimension-al rnodd, `.. ` - - we cast the constitutive postulates in terms of the distention gradient rather than the volume fraction, and we incorporate elastic-plastic effects into the constitutive description of the solid granules.

  3. A nanoporous Ag-Fe mixed-metal-organic framework exhibiting single-crystal-to-single-crystal transformations upon guest exchange.

    PubMed

    Zhang, Yixun; Chen, Banglin; Fronczek, Frank R; Maverick, Andrew W

    2008-06-02

    The reaction of solutions of Fe(Pyac)3 [PyacH=3-(4-pyridyl)-2,4-pentanedione] and AgNO3 produces two types of porous mixed-metal-organic frameworks (M'MOFs). With lower AgNO3 concentrations, the product (M'MOF1) has a 2D honeycomb structure with Ag:Fe=1:1 and pores of ca. 12x16 A. When a higher concentration of AgNO3 is employed, however, the product (M'MOF2) has Ag:Fe=3:2 and a porous 1D ladder structure. A variety of nonpolar solvents serve as guests in M'MOF2: with 1,2-C6H4Cl2, [AgNO3]3[Fe(Pyac)3]2(1,2-C6H4Cl2)5.5 (M'MOF2a); with C6H5Br, [AgNO3]3[Fe(Pyac)3]2(C6H5Br)6 (M'MOF2b). M'MOFs 2a and 2b can be interconverted by treatment with the appropriate solvent, in single-crystal-to-single-crystal transformations.

  4. Welding immiscible polymers with a supercritical fluid.

    PubMed

    Wang, Xiaochu; Sanchez, Isaac C

    2007-11-20

    Polymer adhesion between two immiscible polymers is usually poor because there is little interpenetration of one polymer into the other at the interface. Increasing the width of the interfacial zone can enhance adhesion and mechanical properties. In principle, this can be accomplished by exposing heterogeneous polymer materials to a high-pressure fluid. The fluid can act as a common solvent and promote interpenetration. It also increases chain mobility at the interface, which helps to promote "welding" of the two polymers. A combination of the gradient theory of inhomogeneous systems and the Sanchez-Lacombe equation of state was used to investigate this phenomenon, especially the effect of the high compressibility of supercritical (SC) fluid on the compatibilization of two incompatible polymers. We calculate the interfacial density profile, interfacial thickness, and interfacial tension between the two polymers with and without the SC fluid. We find that the interfacial tension is decreased and the interfacial thickness is increased with high-pressure SC fluid for the ternary systems we have investigated. As the critical point is approached and the SC compressibility becomes large, no enhancement or deleterious effects on compatibilization were observed.

  5. Compatibilized Immiscible Polymer Blends for Gas Separations.

    PubMed

    Panapitiya, Nimanka; Wijenayake, Sumudu; Nguyen, Do; Karunaweera, Chamaal; Huang, Yu; Balkus, Kenneth; Musselman, Inga; Ferraris, John

    2016-07-30

    Membrane-based gas separation has attracted a great deal of attention recently due to the requirement for high purity gasses in industrial applications like fuel cells, and because of environment concerns, such as global warming. The current methods of cryogenic distillation and pressure swing adsorption are energy intensive and costly. Therefore, polymer membranes have emerged as a less energy intensive and cost effective candidate to separate gas mixtures. However, the use of polymeric membranes has a drawback known as the permeability-selectivity tradeoff. Many approaches have been used to overcome this limitation including the use of polymer blends. Polymer blending technology synergistically combines the favorable properties of different polymers like high gas permeability and high selectivity, which are difficult to attain with a single polymer. During polymer mixing, polymers tend to uncontrollably phase separate due to unfavorable thermodynamics, which limits the number of completely miscible polymer combinations for gas separations. Therefore, compatibilizers are used to control the phase separation and to obtain stable membrane morphologies, while improving the mechanical properties. In this review, we focus on immiscible polymer blends and the use of compatibilizers for gas separation applications.

  6. Binary Polymer Brushes of Strongly Immiscible Polymers.

    PubMed

    Chu, Elza; Babar, Tashnia; Bruist, Michael F; Sidorenko, Alexander

    2015-06-17

    The phenomenon of microphase separation is an example of self-assembly in soft matter and has been observed in block copolymers (BCPs) and similar materials (i.e., supramolecular assemblies (SMAs) and homo/block copolymer blends (HBCs)). In this study, we use microphase separation to construct responsive polymer brushes that collapse to generate periodic surfaces. This is achieved by a chemical reaction between the minor block (10%, poly(4-vinylpyridine)) of the block copolymer and a substrate. The major block of polystyrene (PS) forms mosaic-like arrays of grafted patches that are 10-20 nm in size. Depending on the nature of the assembly (SMA, HBC, or neat BCP) and annealing method (exposure to vapors of different solvents or heating above the glass transition temperature), a range of "mosaic" brushes with different parameters can be obtained. Successive grafting of a secondary polymer (polyacrylamide, PAAm) results in the fabrication of binary polymer brushes (BPBs). Upon being exposed to specific selective solvents, BPBs may adopt different conformations. The surface tension and adhesion of the binary brush are governed by the polymer occupying the top stratum. The "mosaic" brush approach allows for a combination of strongly immiscible polymers in one brush. This facilitates substantial contrast in the surface properties upon switching, previously only possible for substrates composed of predetermined nanostructures. We also demonstrate a possible application of such PS/PAAm brushes in a tunable bioadhesion-bioadhesive (PS on top) or nonbioadhesive (PAAm on top) surface as revealed by Escherichia coli bacterial seeding.

  7. Compatibilized Immiscible Polymer Blends for Gas Separations

    PubMed Central

    Panapitiya, Nimanka; Wijenayake, Sumudu; Nguyen, Do; Karunaweera, Chamaal; Huang, Yu; Balkus, Kenneth; Musselman, Inga; Ferraris, John

    2016-01-01

    Membrane-based gas separation has attracted a great deal of attention recently due to the requirement for high purity gasses in industrial applications like fuel cells, and because of environment concerns, such as global warming. The current methods of cryogenic distillation and pressure swing adsorption are energy intensive and costly. Therefore, polymer membranes have emerged as a less energy intensive and cost effective candidate to separate gas mixtures. However, the use of polymeric membranes has a drawback known as the permeability-selectivity tradeoff. Many approaches have been used to overcome this limitation including the use of polymer blends. Polymer blending technology synergistically combines the favorable properties of different polymers like high gas permeability and high selectivity, which are difficult to attain with a single polymer. During polymer mixing, polymers tend to uncontrollably phase separate due to unfavorable thermodynamics, which limits the number of completely miscible polymer combinations for gas separations. Therefore, compatibilizers are used to control the phase separation and to obtain stable membrane morphologies, while improving the mechanical properties. In this review, we focus on immiscible polymer blends and the use of compatibilizers for gas separation applications. PMID:28773766

  8. Experiments on liquid immiscibility along tholeiitic liquid lines of descent

    NASA Astrophysics Data System (ADS)

    Charlier, Bernard; Grove, Timothy L.

    2012-07-01

    Crystallization experiments have been conducted on compositions along tholeiitic liquid lines of descent to define the compositional space for the development of silicate liquid immiscibility. Starting materials have 46-56 wt% SiO2, 11.7-17.7 wt% FeOtot, and Mg-number between 0.29 and 0.36. These melts fall on the basaltic trends relevant for Mull, Iceland, Snake River Plain lavas and for the Sept Iles layered intrusion, where large-scale liquid immiscibility has been recognized. At one atmosphere under anhydrous conditions, immiscibility develops below 1,000-1,020°C in all of these compositionally diverse lavas. Extreme iron enrichment is not necessary; immiscibility also develops during iron depletion and silica enrichment. Variations in melt composition control the development of silicate liquid immiscibility along the tholeiitic trend. Elevation of Na2O + K2O + P2O5 + TiO2 promotes the development of two immiscible liquids. Increasing melt CaO and Al2O3 stabilizes a single-liquid field. New data and published phase equilibria show that anhydrous, low-pressure fractional crystallization is the most favorable condition for unmixing during differentiation. Pressure inhibits immiscibility because it expands the stability field of high-Ca clinopyroxene, which reduces the proportion of plagioclase in the crystallizing assemblage, thus enhancing early iron depletion. Magma mixing between primitive basalt and Fe-Ti-P-rich ferrobasalts can serve to elevate phosphorous and alkali contents and thereby promote unmixing. Water might decrease the temperature and size of the two-liquid field, potentially shifting the binodal (solvus) below the liquidus, leading the system to evolve as a single-melt phase.

  9. Influence of the substrate choice on the L10 phase formation of post-annealed Pt/Fe and Pt/Ag/Fe thin films

    NASA Astrophysics Data System (ADS)

    Vladymyrskyi, I. A.; Karpets, M. V.; Katona, G. L.; Beke, D. L.; Sidorenko, S. I.; Nagata, T.; Nabatame, T.; Chikyow, T.; Ganss, F.; Beddies, G.; Albrecht, M.; Makogon, I. M.

    2014-07-01

    Pt/Fe and Pt/Ag/Fe layered films were deposited by DC magnetron sputtering on MgO(001), SrTiO3(001), and Al2O3(0001) single crystalline substrates at room temperature. The films were post-annealed between 623 K and 1173 K for 30 s in flowing N2 atmosphere. The onset of the L10-FePt phase formation in films deposited on MgO(001) and SrTiO3(001) substrates was observed after annealing between 773 and 873 K, while chemical L10 ordering sets in for Pt/Fe bilayers on Al2O3(0001) at lower temperatures accompanied by strong (001)-texture. It is concluded that elastic stress, arising from the difference in thermal expansion coefficients between film and substrate, promotes ordering and texture formation.

  10. Facile synthesis and enhanced magnetic, photocatalytic properties of one-dimensional Ag@Fe3O4-TiO2

    NASA Astrophysics Data System (ADS)

    Jia, Xiaohua; Dai, Rongrong; Lian, Dandan; Han, Song; Wu, Xiangyang; Song, Haojie

    2017-01-01

    Fe3O4-TiO2 heterostructures were synthesized through co-precipitation method based on TiO2 nanobelts. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibration sample magnetometry (VSM) were used to characterize the heterostructure nanocomposites. The results of XRD proved that the TiO2 nanobelt was anatase which was the most suitable crystal form for photocatalysis. SEM and TEM analysis indicated that Fe3O4 nanoparticles were adhere to TiO2 nanobelts which have one-dimensional structure with 100-200 nm in width. The VSM measurements showed that the photocatalyst can be easily recovered by an extemal magnetic field. X-ray photoelectron spectroscopy (XPS) of Ag@Fe3O4-TiO2 nanocomposites studies confirm that Ag is in Ag0 state. Finally, the photodegradation of rhodamine B (RhB) by the obtained magnetic photocatalyst was investigated via UV-vis absorption spectra. The photocatalytic activity of the composites was observed to be lower compared to bare TiO2 due to the higher degree of recombination reactions after combined with Fe3O4 nanoparticles. After coated the composite of 15% Fe3O4-TiO2 with Ag, the new nanocomposite of Ag@Fe3O4-TiO2 can be easily recovered after photocatalysis by an extemal magnetic field and showed enhanced photocatalytic activity. The mechanisms for the exhibited enhanced photocatalytic effect of Ag nanoparticle decorated Fe3O4-TiO2 nanocomposites with surface heterostructures are discussed.

  11. Method of removing an immiscible lubricant from a refrigeration system and apparatus for same

    DOEpatents

    Spauschus, Hans O.; Starr, Thomas L.

    1999-01-01

    A method of separating an immiscible lubricant from a liquid refrigerant in a refrigerating system including a compressor, a condenser, an expansion device and an evaporator, wherein the expansion device is connected to the condenser by a liquid refrigerant flow line for liquid refrigerant and immiscible lubricant. The method comprising slowing the rate of flow of the liquid refrigerant and immiscible lubricant between the condenser and the expansion device such that the liquid refrigerant and the immiscible lubricant separate based upon differences in density. The method also comprises collecting the separated immiscible lubricant in a collection chamber in fluid communication with the separated immiscible lubricant. Apparatus for performing the method is also disclosed.

  12. Effect of wettability on adverse mobility immiscible floods

    SciTech Connect

    Vives, M.T.; Chang, Y.C.; Mohanty, K.K.

    1995-12-31

    Many immiscible displacements in reservoirs occur at adverse mobility. Effect of wettability on these displacements is not well understood and often ignored in reservoir simulation. Recent macroscopic theories of viscous fingering treat adverse immiscible flows similar to miscible flows, the mixing in the fingered region being controlled by a Todd-Longstaff-type functional form. The wettability of the medium is taken into account only through the use of appropriate relative permeabilities. The goal of this paper is to understand the macroscopic bypassing in adverse mobility immiscible floods. Immiscible displacements are conducted in a quarter 5-spot model in both drainage and imbibition modes at similar effective mobility ratios and viscous-to-gravity numbers. The level of bypassing and gravity override is visualized and measured. Tertiary water-alternating-gas (WAG) displacements are also conducted at various WAG ratios and viscosity ratios. Fractional flow analysis and numerical simulation are used to understand these displacements. Experiments show that macroscopic viscous fingering is present in adverse viscosity immiscible displacements where no saturation shock is expected from 1-D fractional flow theory. Bypassing due to both fingering and gravity override is higher in the drainage mode than in the imbibition mode, with other key parameters being the same. Optimum WAG ratio in water-wet rock is a function of oil/solvent viscosity ratio. The macroscopic flow theory needs to include capillarity and viscous fingering to match these experimental findings.

  13. Late immiscible Fe-rich melt separation during crystallization of highly differentiated siliceous granites

    SciTech Connect

    Silver, L.T.; Woodhead, J.A.; Williams, I.S.; Chappell, B.W.

    1985-01-01

    Observational evidence pointing to late immiscible separation of an Fe-Mn-Ti-rich melt has been obtained for some siliceous granites (SiO/sub 2/ > 70%; alkali oxides > 7 1/2 %; FeO* + MnO/FeO* + MnO + MgO > 0.70). Separation is inferred when crystallization exceeded 95% (vol) and residual melts were isolated and interstitial. Effects on the distribution of incompatible elements (U, Th, REE, Nb, Ta, Ti, P, F) and the paragenesis of the host accessory minerals were immediate and profound. The evidence derived from an exemplar granite includes: (1) diversity and complexity of the accessory mineral assemblage; (2) mappable preferred association of the accessory assemblages with Fe-Ti-Mn-oxides; (3) remarkable discontinuous compositional zonation and reaction relations in various accessory minerals; (4) presence of two distinct compositional variants of some mineral species; (5) interstitial textural and compositional relations to major minerals; (6) unusual textures for the Fe-Ti-Mn-oxide minerals; (7) isotopic evidence that the assemblage is cogenetic. Among several important implications are: (1) the model is suitable for experimental petrology verification; (2) incompatible element behavior during granite crystallization is more complex and more determined by kinetics and local equilibria than has been previously considered; (3) endowment of late differentiates (aplites, pegmatites) may be determined by timing of their separation relative to immiscible liquid separation; (4) separation of incompatible elements from granites by volatile processes may be controlled by volatile/Fe-rich melt equilibria.

  14. Highly efficient and recyclable triple-shelled Ag@Fe3O4@SiO2@TiO2 photocatalysts for degradation of organic pollutants and reduction of hexavalent chromium ions

    NASA Astrophysics Data System (ADS)

    Su, Jianwei; Zhang, Yunxia; Xu, Sichao; Wang, Shuan; Ding, Hualin; Pan, Shusheng; Wang, Guozhong; Li, Guanghai; Zhao, Huijun

    2014-04-01

    Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2 (P25), pure TiO2 microspheres, Fe3O4@SiO2@TiO2 and annealed Ag@Fe3O4@SiO2@TiO2 nanocomposites, the as-obtained amorphous triple-shelled Ag@Fe3O4@SiO2@TiO2 hierarchical nanospheres exhibit a markedly enhanced visible light or sunlight photocatalytic activity towards the photodegradation of methylene blue and photoreduction of hexavalent chromium ions in wastewater. The outstanding photocatalytic activities of the plasmonic photocatalyst are mainly due to the enhanced light harvesting, reduced transport paths for both mass and charge transport, reduced recombination probability of photogenerated electrons/holes, near field electromagnetic enhancement and efficient scattering from the plasmonic nanostructure, increased surface-to-volume ratio and active sites in three dimensional (3D) hierarchical porous nanostructures, and improved photo/chemical stability. More importantly, the hierarchical nanostructured Ag@Fe3O4@SiO2@TiO2 photocatalysts could be easily collected and separated by applying an external magnetic field and reused at least five times without any appreciable reduction in photocatalytic efficiency. The enhanced photocatalytic activity and excellent chemical stability, in combination with the magnetic recyclability, make these multifunctional nanostructures promising candidates to remediate aquatic contaminants and meet the demands of future environmental issues.Herein, we demonstrate the design and fabrication of the well-defined triple-shelled Ag@Fe3O4@SiO2@TiO2 nanospheres with burr-shaped hierarchical structures, in which the multiple distinct functional components are integrated wonderfully into a single nanostructure. In comparison with commercial TiO2

  15. Liquid immiscibility in model bilayer lipid membranes

    NASA Astrophysics Data System (ADS)

    Veatch, Sarah L.

    There is growing evidence that cell plasma membranes are laterally organized into "raft" regions in which particular lipids and proteins are concentrated. These domains have sub-micron dimensions and have been implicated in vital cell functions. Similar liquid domains are observed in model bilayer membrane mixtures that mimick cellular lipid compositions. In model membranes, domains can be large (microns) and can readily form in the absence of proteins. This thesis presents studies of liquid immiscibility in model membrane systems using two experimental methods. By fluorescence microscopy, this thesis documents that miscibility transitions occur in a wide variety of ternary lipid mixtures containing high melting temperature (saturated) lipids, low melting temperature (usually unsaturated) lipids, and cholesterol. I have constructed detailed miscibility phase diagrams for three separate ternary lipid mixtures (DOPC/DPPC/Chol, DOPC/PSM/Chol, and POPC/PSM/Chol). Phase separation is also observed in membranes of lipids extracted from human erythrocytes. NMR experiments probe lipid order and verify the coexistence of a saturated lipid and cholesterol rich liquid ordered (Lo) phase with a more disordered, unsaturated lipid rich liquid crystalline (Lalpha) phase at low temperatures. These experiments also find multiple thermodynamic transitions and lipid organization on different length-scales. This complexity is revealed because fluorescence microscopy and NMR probe lipid order at different length-scales (>1mum vs. ˜100nm). NMR detects small domains (˜80nm) at temperatures just below the miscibility transition, even though micron-scale domains are observed by fluorescent microscopy. NMR does detect large-scale ("100nm) demixing, but at a lower temperature. In addition, it has long been known that >10nm length-scale structure is present in many lipid mixtures containing cholesterol and at least one additional lipid species, though it is shown here that only a subset of

  16. Experimentally Determined Interfacial Area Between Immiscible Fluids in Porous Media

    SciTech Connect

    Crandall, Dustin; Niessner, J; Hassanizadeh, S.M; Smith, Duane

    2008-01-01

    When multiple fluids flow through a porous medium, the interaction between the fluid interfaces can be of great importance. While this is widely recognized in practical applications, numerical models often disregard interactios between discrete fluid phases due to the computational complexity. And rightly so, for this level of detail is well beyond most extended Darcy Law relationships. A new model of two-phase flow including the interfacial area has been proposed by Hassarizadeh and Gray based upon thermodynamic principles. A version of this general equation set has been implemented by Nessner and Hassarizadeh. Many of the interfacial parameters required by this equation set have never been determined from experiments. The work presented here is a description of how the interfacial area, capillary pressure, interfacial velocity and interfacial permeability from two-phase flow experiments in porous media experiments can be used to determine the required parameters. This work, while on-going, has shown the possibility of digitizing images within translucent porous media and identifying the location and behavior of interfaces under dynamic conditions. Using the described methods experimentally derived interfacial functions to be used in larger scale simulations are currently being developed. In summary, the following conclusions can be drawn: (1) by mapping a pore-throat geometry onto an image of immiscible fluid flow, the saturation of fluids and the individual interfaces between the fluids can be identified; (2) the resulting saturation profiles of the low velocity drainage flows used in this study are well described by an invasion percolation fractal scaling; (3) the interfacial area between fluids has been observed to increase in a linear fashion during the initial invasion of the non-wetting fluid; and (4) the average capillary pressure within the entire cell and representative elemental volumes were observed to plateau after a small portion of the volume was

  17. Hydrogenation with monolith reactor under conditions of immiscible liquid phases

    DOEpatents

    Nordquist, Andrew Francis; Wilhelm, Frederick Carl; Waller, Francis Joseph; Machado, Reinaldo Mario

    2002-01-01

    The present invention relates to an improved for the hydrogenation of an immiscible mixture of an organic reactant in water. The immiscible mixture can result from the generation of water by the hydrogenation reaction itself or, by the addition of, water to the reactant prior to contact with the catalyst. The improvement resides in effecting the hydrogenation reaction in a monolith catalytic reactor from 100 to 800 cpi, at a superficial velocity of from 0.1 to 2 m/second in the absence of a cosolvent for the immiscible mixture. In a preferred embodiment, the hydrogenation is carried out using a monolith support which has a polymer network/carbon coating onto which a transition metal is deposited.

  18. Mixing of immiscible polymers using nanoporous coordination templates

    NASA Astrophysics Data System (ADS)

    Uemura, Takashi; Kaseda, Tetsuya; Sasaki, Yotaro; Inukai, Munehiro; Toriyama, Takaaki; Takahara, Atsushi; Jinnai, Hiroshi; Kitagawa, Susumu

    2015-07-01

    The establishment of methodologies for the mixing of immiscible substances is highly desirable to facilitate the development of fundamental science and materials technology. Herein we describe a new protocol for the compatibilization of immiscible polymers at the molecular level using porous coordination polymers (PCPs) as removable templates. In this process, the typical immiscible polymer pair of polystyrene (PSt) and poly(methyl methacrylate) (PMMA) was prepared via the successive homopolymerizations of their monomers in a PCP to distribute the polymers inside the PCP particles. Subsequent dissolution of the PCP frameworks in a chelator solution affords a PSt/PMMA blend that is homogeneous in the range of several nanometers. Due to the unusual compatibilization, the thermal properties of the polymer blend are remarkably improved compared with the conventional solvent-cast blend. This method is also applicable to the compatibilization of PSt and polyacrylonitrile, which have very different solubility parameters.

  19. Containerless low gravity processing of glass forming and immiscible alloys

    NASA Technical Reports Server (NTRS)

    Andrews, J. Barry; Briggs, Craig; Robinson, M. B.

    1990-01-01

    Under normal one-g conditions immiscible alloys segregate extensively during solidification due to sedimentation of the more dense of the immiscible liquid phases. Immiscible (hypermonotectic) gold-rhodium alloys were processed in the 100 meter drop tube under low gravity, containerless conditions to determine the feasibility of producing dispersed structures. Three alloy compositions were utilized. Alloys containing 10 percent by volume of the gold-rich hypermonotectic phase exhibited a tendency for the gold-rich liquid to wet the outer surface of the samples. This wetting tendency led to extensive segregation in several cases. Alloys containing 80 and 90 percent by volume of the gold-rich phase possessed completely different microstructures from the 10 percent samples when processed under low-g, containerless conditions. Several samples exhibited microstructures consisting of well dispersed 2 to 3 microns diameter rhodium-rich spheres in a gold-rich matrix.

  20. Mixing of immiscible polymers using nanoporous coordination templates

    PubMed Central

    Uemura, Takashi; Kaseda, Tetsuya; Sasaki, Yotaro; Inukai, Munehiro; Toriyama, Takaaki; Takahara, Atsushi; Jinnai, Hiroshi; Kitagawa, Susumu

    2015-01-01

    The establishment of methodologies for the mixing of immiscible substances is highly desirable to facilitate the development of fundamental science and materials technology. Herein we describe a new protocol for the compatibilization of immiscible polymers at the molecular level using porous coordination polymers (PCPs) as removable templates. In this process, the typical immiscible polymer pair of polystyrene (PSt) and poly(methyl methacrylate) (PMMA) was prepared via the successive homopolymerizations of their monomers in a PCP to distribute the polymers inside the PCP particles. Subsequent dissolution of the PCP frameworks in a chelator solution affords a PSt/PMMA blend that is homogeneous in the range of several nanometers. Due to the unusual compatibilization, the thermal properties of the polymer blend are remarkably improved compared with the conventional solvent-cast blend. This method is also applicable to the compatibilization of PSt and polyacrylonitrile, which have very different solubility parameters. PMID:26130294

  1. Process for blending coal with water immiscible liquid

    DOEpatents

    Heavin, Leonard J.; King, Edward E.; Milliron, Dennis L.

    1982-10-26

    A continuous process for blending coal with a water immiscible liquid produces a uniform, pumpable slurry. Pulverized raw feed coal and preferably a coal derived, water immiscible liquid are continuously fed to a blending zone (12 and 18) in which coal particles and liquid are intimately admixed and advanced in substantially plug flow to form a first slurry. The first slurry is withdrawn from the blending zone (12 and 18) and fed to a mixing zone (24) where it is mixed with a hot slurry to form the pumpable slurry. A portion of the pumpable slurry is continuously recycled to the blending zone (12 and 18) for mixing with the feed coal.

  2. Measurement of interfacial tension of immiscible liquid pairs in microgravity

    NASA Technical Reports Server (NTRS)

    Weinberg, Michael C.; Neilson, George F.; Baertlein, Carl; Subramanian, R. Shankar; Trinh, Eugene H.

    1994-01-01

    A discussion is given of a containerless microgravity experiment aimed at measuring the interfacial tension of immiscible liquid pairs using a compound drop rotation method. The reasons for the failure to execute such experiments in microgravity are described. Also, the results of post-flight analyses used to confirm our arguments are presented.

  3. Ultrathin-skinned asymmetric membranes by immiscible solvents treatment

    DOEpatents

    Friesen, D.T.; Babcock, W.C.

    1989-11-28

    Improved semipermeable asymmetric fluid separation membranes useful in gas, vapor and liquid separations are disclosed. The membranes are prepared by substantially filling the pores of asymmetric cellulosic semipermeable membranes having a finely porous layer on one side thereof with a water immiscible organic liquid, followed by contacting the finely porous layer with water.

  4. Local lattice-gas model for immiscible fluids

    NASA Technical Reports Server (NTRS)

    Chen, S.; Doolen, G. D.; Eggert, K.; Grunau, D.; Loh, E. Y.

    1991-01-01

    A lattice-gas model is presented for two-dimensional immiscible fluid flows with surface tension that uses strictly local collision rules. Instead of using a local total color flux as Somers and Rem (1991), local colored holes are used to be the memory of particles of the same color. Interactions between walls and fluids are included that produce arbitrary contact angles.

  5. Lattice Boltzmann equation method for multiple immiscible continuum fluids.

    PubMed

    Spencer, T J; Halliday, I; Care, C M

    2010-12-01

    This paper generalizes the two-component algorithm of Sec. , extending it, in Sec. , to describe N>2 mutually immiscible fluids in the isothermal continuum regime. Each fluid has an independent interfacial tension. While retaining all its computational advantages, we remove entirely the empiricism associated with contact behavior in our previous multiple immiscible fluid models [M. M. Dupin, Phys. Rev. E 73, 055701(R) (2006); Med. Eng. Phys. 28, 13 (2006)] while solidifying the physical foundations. Moreover, the model relies upon a fluid-fluid segregation which is simpler, computationally faster, more free of artifacts (i.e., the interfacial microcurrent), and upon an interface-inducing force distribution which is analytic. The method is completely symmetric between any numbers of immiscible fluids and stable over a wide range of directly input interfacial tension. We present data on the steady-state properties of multiple interface model, which are in good agreement with theory [R. E. Johnson and S. S. Sadhal, Annu. Rev. Fluid Mech. 17, 289 (1985)], specifically on the shapes of multidrop systems. Section is an analysis of the kinetic and continuum-scale descriptions of the underlying two-component lattice Boltzmann model for immiscible fluids, extendable to more than two immiscible fluids. This extension requires (i) the use of a more local kinetic equation perturbation which is (ii) free from a reliance on measured interfacial curvature. It should be noted that viewed simply as a two-component method, the continuum algorithm is inferior to our previous methods, reported by Lishchuk [Phys. Rev. E 67, 036701 (2003)] and Halliday [Phys. Rev. E 76, 026708 (2007)]. Greater stability and parameter range is achieved in multiple drop simulations by using the forced multi-relaxation-time lattice Boltzmann method developed, along with (for completeness) a forced exactly incompressible Bhatnagar-Gross-Krook lattice Boltzmann model, in the Appendix. These appended schemes

  6. Segregation of immiscible liquids: From droplet size to plutonic scale

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Wu, B.; Wang, T.; Hui, H.

    2016-12-01

    Silicate liquid immiscibility has been evidenced as discrete glassy droplets in volcanic rocks microscopically. Furthermore, this process has been proposed to have resulted in mafic and felsic fractions on outcrop scale in plutons. However, it is unclear how tiny discrete immiscible liquid droplets could be segregated from a continuous melt (medium) and lead to magmatic differentiation on a chamber scale. The settling of immiscible liquid droplets depends on their sinking (or floating) velocities, which could be described using the Stokes' law. The discrete liquid droplets during settling could collide and coalesce with each other, resulting in larger droplets, which is different from the collision of crystals in the magma. The coalescence can significantly increase the droplet velocities, which are proportional to the square of the droplet radii according to the Stokes' law. In a slow-cooling magma chamber, the exsolution and settling of the discrete liquid droplets may reach "equilibrium", which here we call the steady state. Numerical analyses using population dynamics equations have been carried out to study how physical properties of melts affect the segregation of immiscible liquids at the steady state. Our preliminary results indicate that the residence time (average time it takes for discrete droplets to settle) of discrete melt with viscosity higher than that of the medium could be longer than that of discrete melt with viscosity lower than that of the medium, by even more than one order of magnitude. Furthermore, the residence time is approximately proportional to the square root of the medium viscosity, inversely proportional to the square root of the density difference and inversely proportional to the exsolution rate if the discrete melt is exsolved as initially small droplets ( 10 µm in radius). This study could shed light on understanding the feasibility of formation of plutons through liquid immiscibility in dynamics.

  7. Silicate-natrocarbonatite liquid immiscibility in 1917 eruption combeite-wollastonite nephelinite, Oldoinyo Lengai Volcano, Tanzania: Melt inclusion study

    NASA Astrophysics Data System (ADS)

    Sharygin, Victor V.; Kamenetsky, Vadim S.; Zaitsev, Anatoly N.; Kamenetsky, Maya B.

    2012-11-01

    Primary silicate-melt and carbonate-salt inclusions occur in the phenocrysts (nepheline, fluorapatite, wollastonite, clinopyroxene) in the 1917 eruption combeite-wollastonite nephelinite at Oldoinyo Lengai. Silicate-melt inclusions in nepheline clearly show liquid immiscibility phenomena expressed in the presence of carbonate globules in silicate glass. The coexistence of inclusions with markedly different proportions of silicate glass + vapor-carbonate globule in the core of nepheline phenocrysts, the presence of carbonate-salt inclusions in fluorapatite and our heating experiments strongly suggest that their entrapment began at temperatures higher than 1130 °C in an intermediate chamber when initial carbonated nephelinite melt was heterogeneous and represented a mixture of immiscible liquids. Silicate-natrocarbonatite melt immiscibility took place at high temperature and immiscible nephelinite and carbonatite liquids coexisted over a wide temperature range from ≥ 1130 °C to 600 °C. Homogenization of a carbonate globule (dissolution of the gas bubble in carbonate melt) at 900-940 °C indicates that after separation from silicate magma the natrocarbonatite represented homogeneous liquid in the 900-1130 °C temperature range, whereas below these temperatures immiscible melts of different composition and fluid phase have separated from it. The bulk composition of homogeneous natrocarbonatite melt may be estimated as ≈ 20% CaF2, 40-60% (Na,K)2CO3 and 20-40% CaCO3 based on the coexistence of nyerereite, calcite and fluorite and the rapid phase transition (carbonate aggregate → carbonate liquid) at 550-570 °C observed in vapor-carbonate globules of nepheline-hosted silicate-melt inclusions and on the Na2CO3-CaCO3-CaF2 phase diagram. Silicate glasses of nepheline-hosted immiscible inclusions drastically differ from host nephelinite in the abundance of major and trace elements. They are high peralkaline ((Na + K)/Al — up to 9.5) and virtually free of water (H2

  8. Flow and Reactive Transport of Miscible and Immiscible Solutions in Fractured & Porous Media

    NASA Astrophysics Data System (ADS)

    Ryerson, F. J.; Ezzedine, S. M.; Antoun, T.

    2012-12-01

    Miscible and immiscible flows are important phenomena encountered in many industrial and engineering applications such as hydrothermal systems, oil and gas reservoirs, salt/water intrusion, geological carbon sequestration etc… Under the influence of gravity, the flow of fluids with sufficiently large density ratios may become unstable leading to instabilities, mixing and in some instances reactions at the interfacial contact between fluids. Flow is governed by a combination of momentum and mass conservation equations that describe the flow of the fluid phase and a convection-diffusion equation describing the change of concentration in the fluid phase. When hydrodynamic instabilities develop it may be difficult to use standard grid-based methods to model miscible/immiscible flow because the domains occupied by fluids evolve constantly with time. In the current study, adaptive mesh refinement finite elements method has been used to solve for flow and transport equations. Furthermore, a particle tracking scheme has also been implemented to track the kinematics of swarm of particles injected into the porous fractured media to quantify surface area, sweeping zones, and their impact on porosity changes. Spatial and temporal moments of the fingering instabilities and the development of reaction zones and the impact of kinetic reaction at the fluid/solution interfaces have also been analyzed. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. An informatics guided classification of miscible and immiscible binary alloy systems.

    PubMed

    Zhang, R F; Kong, X F; Wang, H T; Zhang, S H; Legut, D; Sheng, S H; Srinivasan, S; Rajan, K; Germann, T C

    2017-08-29

    The classification of miscible and immiscible systems of binary alloys plays a critical role in the design of multicomponent alloys. By mining data from hundreds of experimental phase diagrams, and thousands of thermodynamic data sets from experiments and high-throughput first-principles (HTFP) calculations, we have obtained a comprehensive classification of alloying behavior for 813 binary alloy systems consisting of transition and lanthanide metals. Among several physics-based descriptors, the slightly modified Pettifor chemical scale provides a unique two-dimensional map that divides the miscible and immiscible systems into distinctly clustered regions. Based on an artificial neural network algorithm and elemental similarity, the miscibility of the unknown systems is further predicted and a complete miscibility map is thus obtained. Impressively, the classification by the miscibility map yields a robust validation on the capability of the well-known Miedema's theory (95% agreement) and shows good agreement with the HTFP method (90% agreement). Our results demonstrate that a state-of-the-art physics-guided data mining can provide an efficient pathway for knowledge discovery in the next generation of materials design.

  10. Research aimed at immiscible CO/sub 2/ flooding

    SciTech Connect

    Chung, F.T.H.; Burchfield, T.E.

    1987-04-27

    The National Institute for Petroleum and Energy Research (Niper) is conducting reserach to develop improved methods for oil recovery by immiscible CO/sub 2/ displacement. The research includes fundamental studies of displacement mechanisms and coreflooding tests for development of an optimal injection method. Heavy oils are the major target of this research. For heavier crudes (API gravity below 25/sup 0/), high viscosity is a major constraint in oil recovery and pipeline transportation. Therefore, reducing oil viscosity becomes critical. Methods currently being used for viscous oil recovery include thermal methods (steamflooding and in situ combustion) and CO/sub 2/ methods. Steamflooding has been widely applied. The number of immiscible CO/sub 2/ projects is small but increasing.

  11. Covalent Fusion of layered Incompatible Gels in Immiscible Solvents

    NASA Astrophysics Data System (ADS)

    Biswas, Santidan; Singh, Awaneesh; Matyjaszewski, Krzysztof; Balazs, Anna C.

    We carry out dissipative particle dynamics (DPD) simulations to model a two layered stackable gel where the gels are incompatible and are present in immiscible solvent. The bottom layer of the gel is created first and then a solution of new initiators, monomers and cross-linkers is introduced on top of it. These components then undergo polymerization and form the second gel layer. We study all possible combinations of free radical polymerization (FRP) and atom transfer radical polymerization (ATRP) mechanisms with the two layers of the gel. For example, the bottom layer gel is created via ATRP, whereas the top layer gel follows FRP. Our focus is to do a systematic study of all these combinations and find out the factors responsible for combining two incompatible gels in immiscible solvents.

  12. Spontaneous vitrification in an immiscible Fe-Cu system

    NASA Astrophysics Data System (ADS)

    Huang, L. J.; Liu, B. X.

    1990-10-01

    Spontaneous vitrification was observed in the equilibrium immiscible Fe-Cu system. The metastable phase before vitrification was an icosahedral incommensurate phase which was formed by an ion beam mixing of Fe-Cu multilayer films at room temperature and subsequent high-temperature thermal annealing. The electrical and magnetic properties of the icosahedral phase are also reported, and the relation with spontaneous vitrification is discussed.

  13. Immiscible fluid: Heat of fusion heat storage system

    NASA Technical Reports Server (NTRS)

    Edie, D. D.; Melsheimer, S. S.; Mullins, J. C.

    1980-01-01

    Both heat and mass transfer in direct contact aqueous crystallizing systems were studied as part of a program desig- ned to evaluate the feasibility of direct contact heat transfer in phase change storage using aqueous salt system. Major research areas, discussed include (1) crystal growth velocity study on selected salts; (2) selection of salt solutions; (3) selection of immiscible fluids; (4) studies of heat transfer and system geometry; and (5) system demonstration.

  14. Immiscible hydrocarbon fluids in the deep carbon cycle

    PubMed Central

    Huang, Fang; Daniel, Isabelle; Cardon, Hervé; Montagnac, Gilles; Sverjensky, Dimitri A.

    2017-01-01

    The cycling of carbon between Earth's surface and interior governs the long-term habitability of the planet. But how carbon migrates in the deep Earth is not well understood. In particular, the potential role of hydrocarbon fluids in the deep carbon cycle has long been controversial. Here we show that immiscible isobutane forms in situ from partial transformation of aqueous sodium acetate at 300 °C and 2.4–3.5 GPa and that over a broader range of pressures and temperatures theoretical predictions indicate that high pressure strongly opposes decomposition of isobutane, which may possibly coexist in equilibrium with silicate mineral assemblages. These results complement recent experimental evidence for immiscible methane-rich fluids at 600–700 °C and 1.5–2.5 GPa and the discovery of methane-rich fluid inclusions in metasomatized ophicarbonates at peak metamorphic conditions. Consequently, a variety of immiscible hydrocarbon fluids might facilitate carbon transfer in the deep carbon cycle. PMID:28604740

  15. Immiscible hydrocarbon fluids in the deep carbon cycle

    NASA Astrophysics Data System (ADS)

    Huang, Fang; Daniel, Isabelle; Cardon, Hervé; Montagnac, Gilles; Sverjensky, Dimitri A.

    2017-06-01

    The cycling of carbon between Earth's surface and interior governs the long-term habitability of the planet. But how carbon migrates in the deep Earth is not well understood. In particular, the potential role of hydrocarbon fluids in the deep carbon cycle has long been controversial. Here we show that immiscible isobutane forms in situ from partial transformation of aqueous sodium acetate at 300 °C and 2.4-3.5 GPa and that over a broader range of pressures and temperatures theoretical predictions indicate that high pressure strongly opposes decomposition of isobutane, which may possibly coexist in equilibrium with silicate mineral assemblages. These results complement recent experimental evidence for immiscible methane-rich fluids at 600-700 °C and 1.5-2.5 GPa and the discovery of methane-rich fluid inclusions in metasomatized ophicarbonates at peak metamorphic conditions. Consequently, a variety of immiscible hydrocarbon fluids might facilitate carbon transfer in the deep carbon cycle.

  16. Electric-Field-Assisted Droplet Dispensing on Immiscible Fluids

    NASA Astrophysics Data System (ADS)

    Uhm, Taewoong; Hong, Jiwoo; Lee, Sang Joon; Kang, In Seok

    2014-11-01

    Dispensing tiny droplets is a basic and crucial process in numerous practical applications, such as printed electronics, DNA microarray, and digital microfluidics. The precise positioning with demanded size of droplets is the main issue of dispensing tiny droplets. Furthermore, capability of dispensing charged droplets on the immiscible fluids could bring out more utilities. In this work, we demonstrate the droplet dispensing on immiscible fluids by means of electrical charge concentration (ECC). This results from the fact that the droplet is generated by electric force caused by electric induction between the surface of droplet and the immiscible fluid. The temporal evolution of the droplet-dispensing process was observed consecutively with a high-speed camera. In addition, the relationship between the size of dispensed droplet and the parameters, such as physical properties of fluids and electrical field strength, is established. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (Grant Number: 2013R1A1A2011956).

  17. Lattice Boltzmann equation method for multiple immiscible continuum fluids

    NASA Astrophysics Data System (ADS)

    Spencer, T. J.; Halliday, I.; Care, C. M.

    2010-12-01

    This paper generalizes the two-component algorithm of Sec. , extending it, in Sec. , to describe N>2 mutually immiscible fluids in the isothermal continuum regime. Each fluid has an independent interfacial tension. While retaining all its computational advantages, we remove entirely the empiricism associated with contact behavior in our previous multiple immiscible fluid models [M. M. Dupin , Phys. Rev. E 73, 055701(R) (2006)10.1103/PhysRevE.73.055701; Med. Eng. Phys. 28, 13 (2006)10.1016/j.medengphy.2005.04.015] while solidifying the physical foundations. Moreover, the model relies upon a fluid-fluid segregation which is simpler, computationally faster, more free of artifacts (i.e., the interfacial microcurrent), and upon an interface-inducing force distribution which is analytic. The method is completely symmetric between any numbers of immiscible fluids and stable over a wide range of directly input interfacial tension. We present data on the steady-state properties of multiple interface model, which are in good agreement with theory [R. E. Johnson and S. S. Sadhal, Annu. Rev. Fluid Mech. 17, 289 (1985)10.1146/annurev.fl.17.010185.001445], specifically on the shapes of multidrop systems. Section is an analysis of the kinetic and continuum-scale descriptions of the underlying two-component lattice Boltzmann model for immiscible fluids, extendable to more than two immiscible fluids. This extension requires (i) the use of a more local kinetic equation perturbation which is (ii) free from a reliance on measured interfacial curvature. It should be noted that viewed simply as a two-component method, the continuum algorithm is inferior to our previous methods, reported by Lishchuk [Phys. Rev. E 67, 036701 (2003)]10.1103/PhysRevE.76.036701 and Halliday [Phys. Rev. E 76, 026708 (2007)]10.1103/PhysRevE.76.026708. Greater stability and parameter range is achieved in multiple drop simulations by using the forced multi-relaxation-time lattice Boltzmann method developed

  18. Pore-scale modeling of moving contact line problems in immiscible two-phase flow.

    NASA Astrophysics Data System (ADS)

    Kucala, A.; Noble, D.; Martinez, M. J.

    2016-12-01

    Two immiscible fluids in static equilibrium form a common interface along a solid surface, characterized as the static contact (wetting) angle and is a function of surface geometry, intermolecular forces, and interfacial surface energies manifested as interfacial tension. This static configuration may become perturbed due to external force imbalances (mass injection, pressure gradients, buoyancy, etc.) and the contact line location and interface curvature becomes dynamic. Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. The moving two-phase interface is tracked using the level set method and discretized with the conformal decomposition finite element method (CDFEM), allowing for surface tension effects to be computed at the exact interface location. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000

  19. Method of removing an immiscible lubricant from a refrigeration system and apparatus for same

    SciTech Connect

    Spauschus, H.O.; Starr, T.L.

    1999-03-30

    A method is described for separating an immiscible lubricant from a liquid refrigerant in a refrigerating system including a compressor, a condenser, an expansion device and an evaporator, wherein the expansion device is connected to the condenser by a liquid refrigerant flow line for liquid refrigerant and immiscible lubricant. The method comprising slowing the rate of flow of the liquid refrigerant and immiscible lubricant between the condenser and the expansion device such that the liquid refrigerant and the immiscible lubricant separate based upon differences in density. The method also comprises collecting the separated immiscible lubricant in a collection chamber in fluid communication with the separated immiscible lubricant. Apparatus for performing the method is also disclosed. 3 figs.

  20. Method of removing an immiscible lubricant from a refrigeration system and apparatus for same

    DOEpatents

    Spauschus, H.O.; Starr, T.L.

    1999-03-30

    A method is described for separating an immiscible lubricant from a liquid refrigerant in a refrigerating system including a compressor, a condenser, an expansion device and an evaporator, wherein the expansion device is connected to the condenser by a liquid refrigerant flow line for liquid refrigerant and immiscible lubricant. The method comprising slowing the rate of flow of the liquid refrigerant and immiscible lubricant between the condenser and the expansion device such that the liquid refrigerant and the immiscible lubricant separate based upon differences in density. The method also comprises collecting the separated immiscible lubricant in a collection chamber in fluid communication with the separated immiscible lubricant. Apparatus for performing the method is also disclosed. 3 figs.

  1. Coalescence of Immiscible Liquid Metal Drop on Graphene

    PubMed Central

    Li, Tao; Li, Jie; Wang, Long; Duan, Yunrui; Li, Hui

    2016-01-01

    Molecular dynamics simulations were performed to investigate the wetting and coalescence of liquid Al and Pb drops on four carbon-based substrates. We highlight the importance of the microstructure and surface topography of substrates in the coalescence process. Our results show that the effect of substrate on coalescence is achieved by changing the wettability of the Pb metal. Additionally, we determine the critical distance between nonadjacent Al and Pb films required for coalescence. These findings improve our understanding of the coalescence of immiscible liquid metals at the atomistic level. PMID:27667589

  2. Immiscible solvents enabled nanostructure formation for efficient polymer photovoltaic cells.

    PubMed

    Lee, Dong-Hyun; Michael Yang, Yang; You, Jingbi; Richard, Eric; Li, Gang

    2014-07-25

    Organic photovoltaics (OPVs) fabricated via solution processing are an attractive way to realize low cost solar energy harvesting. Bulk heterojunction (BHJ) devices are the most successful design, but their morphology is less controllable. In this manuscript, we describe a simple approach to realize 'ordered' BHJ morphology using two immiscible solvents with different boiling point and a quasi-bilayer approach. Tunable fine structures were demonstrated in poly(3-hexylthiophene) (P3HT) and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) model systems, and the devices with optimized fine structure showed a 33% efficiency enhancement compared to those with a planar bilayer structure.

  3. Oil ganglion dynamics during immiscible displacement: model formulation

    SciTech Connect

    Payatakes, A.C.; Ng, K.M.; Flumerfelt, R.W.

    1980-05-01

    A model is formulated in order to study the transient behavior of oil ganglion populations during immiscible displacement in oil recovery processes. The model is composed of 3 components: a suitable model for granular porous media; a stochastic simulation method capable of predicting the expected fate (mobilization, breakup, stranding) of solitary oil ganglia moving through granular porous media; and 2 coupled ganglion population balance equations, one applying to moving ganglia and the other to stranded ones. The porous medium model consists of a regular network of randomly sized unit cells of the constricted tube type. 32 references.

  4. The evolution of immiscible silicate and fluoride melts: Implications for REE ore-genesis

    NASA Astrophysics Data System (ADS)

    Vasyukova, O.; Williams-Jones, A. E.

    2016-01-01

    The Mid-Proterozoic peralkaline Strange Lake pluton (Québec-Labrador, Canada) exhibits extreme enrichment in high field strength elements (HFSE), including the rare earth elements (REE), particularly in pegmatites. On the basis of a study of melt inclusions, we proposed recently that fluoride-silicate melt immiscibility played an important and perhaps dominant role in concentrating the REE within the pluton. Here we present further evidence for silicate-fluoride immiscibility at Strange Lake from a sample of the hypersolvus granite, which contains an inclusion composed largely of REE and HFSE minerals. The inclusion (∼5 cm in diameter) comprises a narrow rim containing chevkinite-(Ce) and zircon in a fluorite matrix, a core of fluorbritholite-(Ce) and bastnäsite-(Ce) and a transition zone between the rim and the core consisting of a fine-grained intergrowth of bastnäsite-(Ce), gagarinite-(Y) and fluorite. We propose that the inclusion formed as a result of silicate-fluoride immiscibility, which occurred early in the emplacement history of the Strange Lake pluton, and that it represents the fluoride melt. After separation of the two melts, the boundary between them acted as a locus of crystallisation, where crystals formed repeatedly due to heterogeneous (surface catalysed) nucleation. Zircon crystallised shortly after melt phase separation, and was followed by the growth of perthite together with arfvedsonite and quartz. As a result, the silicate melt surrounding the fluoride inclusion became enriched in volatiles that facilitated crystallisation of progressively larger crystals in the inclusion; large crystals of arfvedsonite and perthite were succeeded by even larger crystals of quartz. Massive crystallisation of chevkinite-(Ce) followed, forming the rim of the inclusion. The fluoride melt, which constituted the matrix to the silicate minerals and chevkinite-(Ce), crystallised after chevkinite-(Ce), forming fluorbritholite-(Ce) and fluorite. Aqueous fluid

  5. The rotating movement of three immiscible fluids - A benchmark problem

    USGS Publications Warehouse

    Bakker, M.; Oude, Essink G.H.P.; Langevin, C.D.

    2004-01-01

    A benchmark problem involving the rotating movement of three immiscible fluids is proposed for verifying the density-dependent flow component of groundwater flow codes. The problem consists of a two-dimensional strip in the vertical plane filled with three fluids of different densities separated by interfaces. Initially, the interfaces between the fluids make a 45??angle with the horizontal. Over time, the fluids rotate to the stable position whereby the interfaces are horizontal; all flow is caused by density differences. Two cases of the problem are presented, one resulting in a symmetric flow field and one resulting in an asymmetric flow field. An exact analytical solution for the initial flow field is presented by application of the vortex theory and complex variables. Numerical results are obtained using three variable-density groundwater flow codes (SWI, MOCDENS3D, and SEAWAT). Initial horizontal velocities of the interfaces, as simulated by the three codes, compare well with the exact solution. The three codes are used to simulate the positions of the interfaces at two times; the three codes produce nearly identical results. The agreement between the results is evidence that the specific rotational behavior predicted by the models is correct. It also shows that the proposed problem may be used to benchmark variable-density codes. It is concluded that the three models can be used to model accurately the movement of interfaces between immiscible fluids, and have little or no numerical dispersion. ?? 2003 Elsevier B.V. All rights reserved.

  6. Domain walls and bubble droplets in immiscible binary Bose gases

    NASA Astrophysics Data System (ADS)

    Filatrella, G.; Malomed, Boris A.; Salerno, Mario

    2014-10-01

    The existence and stability of domain walls (DWs) and bubble-droplet (BD) states in binary mixtures of quasi-one-dimensional ultracold Bose gases with inter- and intraspecies repulsive interactions is considered. Previously, DWs were studied by means of coupled systems of Gross-Pitaevskii equations (GPEs) with cubic terms, which model immiscible binary Bose-Einstein condensates (BECs). We address immiscible BECs with two- and three-body repulsive interactions, as well as binary Tonks-Girardeau (TG) gases, using systems of GPEs with cubic and quintic nonlinearities for the binary BEC, and coupled nonlinear Schrödinger equations with quintic terms for the TG gases. Exact DW solutions are found for the symmetric BEC mixture, with equal intraspecies scattering lengths. Stable asymmetric DWs in the BEC mixtures with dissimilar interactions in the two components, as well as of symmetric and asymmetric DWs in the binary TG gas, are found by means of numerical and approximate analytical methods. In the BEC system, DWs can be easily put in motion by phase imprinting. Combining a DW and anti-DW on a ring, we construct BD states for both the BEC and TG models. These consist of a dark soliton in one component (the "bubble"), and a bright soliton (the "droplet") in the other. In the BEC system, these composite states are mobile, too.

  7. BHR equations re-derived with immiscible particle effects

    SciTech Connect

    Schwarzkopf, John Dennis; Horwitz, Jeremy A.

    2015-05-01

    Compressible and variable density turbulent flows with dispersed phase effects are found in many applications ranging from combustion to cloud formation. These types of flows are among the most challenging to simulate. While the exact equations governing a system of particles and fluid are known, computational resources limit the scale and detail that can be simulated in this type of problem. Therefore, a common method is to simulate averaged versions of the flow equations, which still capture salient physics and is relatively less computationally expensive. Besnard developed such a model for variable density miscible turbulence, where ensemble-averaging was applied to the flow equations to yield a set of filtered equations. Besnard further derived transport equations for the Reynolds stresses, the turbulent mass flux, and the density-specific volume covariance, to help close the filtered momentum and continuity equations. We re-derive the exact BHR closure equations which include integral terms owing to immiscible effects. Physical interpretations of the additional terms are proposed along with simple models. The goal of this work is to extend the BHR model to allow for the simulation of turbulent flows where an immiscible dispersed phase is non-trivially coupled with the carrier phase.

  8. Seismological constraints on core composition from Fe-O-S liquid immiscibility.

    PubMed

    Helffrich, George; Kaneshima, Satoshi

    2004-12-24

    Earth's core is composed primarily of iron (Fe) with about 10% by weight of lighter elements. The lighter elements are progressively enriched in the liquid outer core as the core cools and the inner core crystallizes. Thermodynamic modeling of Fe-O-S liquids shows that immiscible liquids can exist at outer-core pressures (136 to 330 gigapascals) at temperatures below 5200 kelvin and lead to layering in the outer core if the concentrations of the lighter elements are high enough. We found no evidence for layering in the outer core in the travel times and wave forms of P4KP seismic waves that reflect internally in the core. The absence of layers therefore constrains outer-core compositions in the Fe-O-S system to be no richer than 6 +/- 1 weight % (wt %) O and 2 to 15 wt % S. A single core liquid composition of 10.5 +/- 3.5 wt % S and 1.5 +/- 1.5 wt % O is compatible with wave speeds and densities throughout the outer core.

  9. Silicate liquid immiscibility in magmas and in the system K2O-FeO-AI2O3-SiO2: an example of serendipity

    USGS Publications Warehouse

    Roedder, E.

    1978-01-01

    system, compositions near it show a number of phase changes and large amounts of crystallization with small temperature changes, generally in the range 1100-1150 C. Similar low-temperature, high-alkali immiscibility was discovered in a few exploratory runs in the equivalent systems with Rb or Cs substituting for K. But not in those with Li or Na. A review of the compositions and general behavior of systems involving immiscibility, both stable and metastable, and of the evidence for natural immiscibility. indicates that it may be a much more common feature than generally thought. Several examples of natural immiscibility are detailed; most yield a felsic. alkali-aluminosilicate melt and a mafic melt. from a wide variety of generally basaltic parental magmas, both under- and over saturated. Unfortunately, the best line of evidence for immiscibility in terrestrial rocks, a sharply defined meniscus between two compositionally disparate glasses, is by its very nature self-destructing, since it is effectively eliminated by either crystallization or gravitative separation and coalescence into separate magmas. Verification of operation of the exosolutionor 'splitting' process on a large scale will probably require careful study of isotopic and trace element partitioning in both laboratory and field. ?? 1978.

  10. Growth of normally-immiscible materials (NIMs), binary alloys, and metallic fibers by hyperbaric laser chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Maxwell, J. L.; Black, M. R.; Chavez, C. A.; Maskaly, K. R.; Espinoza, M.; Boman, M.; Landstrom, L.

    2008-06-01

    This work demonstrates that two or more elements of negligible solubility (and no known phase diagram) can be co-deposited in fiber form by hyperbaric-pressure laser chemical vapor deposition (HP-LCVD). For the first time, Hg-W alloys were grown as fibers from mixtures of tungsten hexafluoride, mercury vapor, and hydrogen. This new class of materials is termed normally-immiscible materials (NIMs), and includes not only immiscible materials, but also those elemental combinations that have liquid states at exclusive temperatures. This work also demonstrates that a wide variety of other binary and ternary alloys, intermetallics, and mixtures can be grown as fibers, e.g. silicon-tungsten, aluminum-silicon, boron-carbon-silicon, and titanium-carbon-nitride. In addition, pure metallic fibers of aluminum, titanium, and tungsten were deposited, demonstrating that materials of high thermal conductivity can indeed be grown in three-dimensions, provided sufficient vapor pressures are employed. A wide variety of fiber properties and microstructures resulted depending on process conditions; for example, single crystals, fine-grained alloys, and glassy metals could be deposited.

  11. Ferrobasalt-rhyolite immiscibility in tholeiitic volcanic and plutonic series (Invited)

    NASA Astrophysics Data System (ADS)

    Charlier, B.; Namur, O.; Kamenetsky, V. S.; Grove, T. L.

    2013-12-01

    One atmosphere experiments show that silicate liquid immiscibility develops between Fe-rich and Si-rich melts below 1000-1020°C in compositionally diverse lavas that represent classical tholeiitic trends, such as Mull, Iceland, Snake River Plain and Sept Iles. Extreme iron enrichment along the evolution trend is not necessary; immiscibility also develops during iron depletion and silica enrichment after Fe-Ti oxide saturation. Natural liquid lines of descent for major tholeiitic series also approach or intersect the experimentally-defined compositional space of immiscibility. The importance of ferrobasalt-rhyolite unmixing in both volcanic and plutonic environments is supported by worldwide occurrence of immiscible globules in the mesostasis of erupted basalts, and by unmixed melt inclusions in cumulus phases of major layered intrusions such as Sept Iles, Skaergaard and Sudbury. A clear case of liquid immiscibility is also recorded in intrusive tholeiitic gabbros from the Siberian Large Igneous Province and is evidenced by textures and compositions of millimeter-sized silicate melt pools trapped in native iron. An important implication of immiscibility in natural ferrobasaltic provinces is the development of a compositional gap characterized by the absence of intermediate compositions, a major feature observed in many tholeiitic provinces and referred to as the Daly gap. The compositions of experimental silica-rich immiscible melts coincide with those of natural rhyolites with high FeOtot and low Al2O3, which suggests a potential role for large-scale immiscibility in the petrogenesis of late-stage ferroan silicic melts. No evidence for the paired ferrobasaltic melt is observed in volcanic provinces, probably because of its uneruptable characteristics. Instead, Fe-Ti×P-rich gabbros crystallized at depth and are the cumulate products of immiscible Fe-rich melts in plutonic settings, a feature clearly evidenced in the Sept Iles intrusion. The production of

  12. Application of the boundary integral method to immiscible displacement problems

    SciTech Connect

    Masukawa, J.; Horne, R.N.

    1988-08-01

    This paper presents an application of the boundary integral method (BIM) to fluid displacement problems to demonstrate its usefulness in reservoir simulation. A method for solving two-dimensional (2D), piston-like displacement for incompressible fluids with good accuracy has been developed. Several typical example problems with repeated five-spot patterns were solved for various mobility ratios. The solutions were compared with the analytical solutions to demonstrate accuracy. Singularity programming was found to be a major advantage in handling flow in the vicinity of wells. The BIM was found to be an excellent way to solve immiscible displacement problems. Unlike analytic methods, it can accommodate complex boundary shapes and does not suffer from numerical dispersion at the front.

  13. Study on processing immiscible materials in zero gravity

    NASA Technical Reports Server (NTRS)

    Reger, J. L.; Mendelson, R. A.

    1975-01-01

    An experimental investigation was conducted to evaluate mixing immiscible metal combinations under several process conditions. Under one-gravity, these included thermal processing, thermal plus electromagnetic mixing, and thermal plus acoustic mixing. The same process methods were applied during free fall on the MSFC drop tower facility. The design is included of drop tower apparatus to provide the electromagnetic and acoustic mixing equipment, and a thermal model was prepared to design the specimen and cooling procedure. Materials systems studied were Ca-La, Cd-Ga and Al-Bi; evaluation of the processed samples included the morphology and electronic property measurements. The morphology was developed using optical and scanning electron microscopy and microprobe analyses. Electronic property characterization of the superconducting transition temperatures were made using an impedance change-tuned coil method.

  14. Flow behaviour of negatively buoyant jets in immiscible ambient fluid

    NASA Astrophysics Data System (ADS)

    Geyer, A.; Phillips, J. C.; Mier-Torrecilla, M.; Idelsohn, S. R.; Oñate, E.

    2012-01-01

    In this paper we investigate experimentally the injection of a negatively buoyant jet into a homogenous immiscible ambient fluid. Experiments are carried out by injecting a jet of dyed fresh water through a nozzle in the base of a cylindrical tank containing rapeseed oil. The fountain inlet flow rate and nozzle diameter were varied to cover a wide range of Richardson Ri (8 × 10-4 < Ri < 1.98), Reynolds Re (467 < Re < 5,928) and Weber We (2.40 < We < 308.56) numbers. Based on the Re, Ri and We values for the experiments, we have determined a regime map to define how these values may control the occurrence of the observed flow types. Whereas Ri plays a stronger role when determining the maximum penetration height, the effect of the Reynolds number is stronger predicting the flow behaviour for a specific nozzle diameter and injection velocity.

  15. A novel coarsening mechanism of droplets in immiscible fluid mixtures

    NASA Astrophysics Data System (ADS)

    Shimizu, Ryotaro; Tanaka, Hajime

    2015-06-01

    In our daily lives, after shaking a salad dressing, we see the coarsening of oil droplets suspended in vinegar. Such a demixing process is observed everywhere in nature and also of technological importance. For a case of high droplet density, domain coarsening proceeds with inter-droplet collisions and the resulting coalescence. This phenomenon has been explained primarily by the so-called Brownian-coagulation mechanism: stochastic thermal forces exerted by molecules induce random motion of individual droplets, causing accidental collisions and subsequent interface-tension-driven coalescence. Contrary to this, here we demonstrate that the droplet motion is not random, but hydrodynamically driven by the composition Marangoni force due to an interfacial tension gradient produced in each droplet as a consequence of composition correlation among droplets. This alters our physical understanding of droplet coarsening in immiscible liquid mixtures on a fundamental level.

  16. Purification of cell subpopulations via immiscible filtration assisted by surface tension (IFAST).

    PubMed

    Berry, Scott M; Strotman, Lindsay N; Kueck, Jessica D; Alarid, Elaine T; Beebe, David J

    2011-12-01

    The selective isolation of a sub-population of cells from a larger, mixed population is a critical preparatory process to many biomedical assays. Here, we present a new cell isolation platform with a unique set of advantages over existing devices. Our technology, termed Immiscible Filtration Assisted by Surface Tension, exploits physical phenomena associated with the microscale to establish fluidic barriers composed of immiscible liquids. By attaching magnetically-responsive particles to a target cell population via immunocapture, we can selectively transport this population across the immiscible barrier and into a separate aqueous solution. The high interfacial energy associated with the immiscible phase / aqueous phase boundaries prevents unwanted cells or other contaminants from inadvertently crossing the immiscible phase. We have demonstrated, using fluorescent particles, stromal cells, and whole blood as "background", that we can successfully isolate ~70% of a target breast cancer cell population with an average purity of >80%. Increased purity was obtained by coupling two immiscible barriers in series, a modification that only slightly increases operational complexity. Furthermore, several samples can be processed in parallel batches in a near-instantaneous manner without the requirement of any washing, which can cause dilution (negative selection) or significant uncontrolled loss (positive selection) of target cells. Finally, cells were observed to remain viable and proliferative following traverse through the immiscible phase, indicating that this process is suitable for a variety of downstream assays, including those requiring intact living cells.

  17. Partitioning of Nb, Mo, Ba, Ce, Pb, Th and U between immiscible carbonate and silicate liquids: Evaluating the effects of P2O5,F, and carbonate composition

    NASA Technical Reports Server (NTRS)

    Jones, J. H.; Walker, D.

    1993-01-01

    Previously we have reported carbonate liq./silicate liq. partition coefficients (D) for a standard suite of trace elements (Nb, Mo, Ba, Ce, Pb, Th, and U) and Ra and Pa as well. In brief, we have found that immiscible liquid partitioning is a strong function of temperature. As the critical temperature of the carbonate-silicate solvus is approached, all partition coefficients approach unity. Additionally, for the overwhelming majority of the partitioning elements, InD is a linear function of 'ionic field strength,' z/r, where z is the charge of the partitioned cation and r is its ionic radius.

  18. Particle Swarm Transport through Immiscible Fluid Layers in a Fracture

    NASA Astrophysics Data System (ADS)

    Teasdale, N. D.; Boomsma, E.; Pyrak-Nolte, L. J.

    2011-12-01

    Immiscible fluids occur either naturally (e.g. oil & water) or from anthropogenic processes (e.g. liquid CO2 & water) in the subsurface and complicate the transport of natural or engineered micro- or nano-scale particles. In this study, we examined the effect of immiscible fluids on the formation and evolution of particle swarms in a fracture. A particle swarm is a collection of colloidal-size particles in a dilute suspension that exhibits cohesive behavior. Swarms fall under gravity with a velocity that is greater than the settling velocity of a single particle. Thus a particle swarm of colloidal contaminants can potentially travel farther and faster in a fracture than expected for a dispersion or emulsion of colloidal particles. We investigated the formation, evolution, and break-up of colloidal swarms under gravity in a uniform aperture fracture as hydrophobic/hydrophyllic particle swarms move across an oil-water interface. A uniform aperture fracture was fabricated from two transparent acrylic rectangular prisms (100 mm x 50 mm x 100 mm) that are separated by 1, 2.5, 5, 10 or 50 mm. The fracture was placed, vertically, inside a glass tank containing a layer of pure silicone oil (polydimethylsiloxane) on distilled water. Along the length of the fracture, 30 mm was filled with oil and 70 mm with water. Experiments were conducted using silicone oils with viscosities of 5, 10, 100, or 1000 cSt. Particle swarms (5 μl) were comprised of a 1% concentration (by mass) of 25 micron glass beads (hydrophilic) suspended in a water drop, or a 1% concentration (by mass) of 3 micron polystyrene fluorescent beads (hydrophobic) suspended in a water drop. The swarm behavior was imaged using an optical fluorescent imaging system composed of a CCD camera and by green (525 nm) LED arrays for illumination. Swarms were spherical and remained coherent as they fell through the oil because of the immiscibility of oil and water. However, as a swarm approached the oil-water interface, it

  19. Field and modelling studies of immiscible fluid flow above a contaminated water-table aquifer

    USGS Publications Warehouse

    Herkelrath, W.N.; Essaid, H.I.; Hess, K.M.

    1991-01-01

    A method was developed for measuring the spatial distribution of immiscible liquid contaminants in the subsurface. Fluid saturation distributions measured at a crude-oil spill site were used to test a numerical multiphase flow model.

  20. Immiscible phase incorporation during directional solidification of hypermonotectics

    NASA Technical Reports Server (NTRS)

    Andrews, J. Barry; Merrick, Roger A.

    1993-01-01

    Solidification processes in immiscible samples were investigated by directly observing the events taking place at the solid-liquid interface during directional solidification. Visualization of these events was made possible through the use of a transparent metal analog system and a temperature gradient stage assembly fitted to an optical microscope. The immiscible transparent analog system utilized was the succinonitrile-glycerol system. This system has been shown to exhibit the same morphological transitions as observed in metallic alloys of monotectic composition. Both monotectic and hypermonotectic composition samples were directionally solidified in order to gain an improved understanding of the manner in which the excess hypermonotectic liquid is incorporated into the solidifying structure. The processing conditions utilized prevented sedimentation of the excess hypermonotectic liquid by directionally solidifying the samples in very thin (13 microns), horizontally oriented cells. High thermal gradient to growth rate ratios (G/R) were used in an effort to prevent constitutional supercooling and the subsequent formation of L(sub 2) droplets in advance of the solidification front during the growth of fibrous composite structures. Results demonstrated that hypermonotectic composites could be produced in samples up to two weight percent off of the monotectic composition by using a G/R ratio greater than or equal to 4.6 x 10(exp 4) C(s)/mm(sup 2) to avoid constitutional supercooling. For hypermonotectic samples processed with G/R ratios below 4.6 x 10(exp 4) C(s)/mm(sup 2), constitutional supercooling occurred and resulted in slight interfacial instability. For these samples, two methods of incorporation of the hypermonotectic liquid were observed and are reported. The correlation between the phase spacing, lambda, and the growth rate, R, was examined and was found to obey a relationship generally associated with a diffusion controlled coupled growth process. For

  1. Capillary pinning of immiscible gravity currents in porous media

    NASA Astrophysics Data System (ADS)

    Zhao, B.; MacMinn, C. W.; Huppert, H. E.; Juanes, R.

    2013-12-01

    Gravity currents in porous media have attracted interest recently in the context of geological carbon dioxide (CO2) storage, where supercritical CO2 is captured from the flue gas of power plants and injected underground into deep saline aquifers. Capillarity can be important in the spreading and migration of the buoyant CO2 after injection because the typical pore size is very small (~10-100 microns), but the impact of capillarity on these flows is not well understood. Here, we study the impact of capillarity on the buoyant spreading of a finite gravity current of non-wetting fluid into a dense, wetting fluid in a vertically confined, horizontal aquifer. We show via simple, table-top experiments using glass bead packs that capillary pressure hysteresis pins a portion of the fluid-fluid interface. The horizontal extent of the pinned portion of the interface grows over time and this is responsible for ultimately stopping the spreading of the buoyant current after a finite distance. In addition, capillarity blunts the leading edge of the buoyant current. We demonstrate through micromodel experiments that the characteristic height of the nose of the current is controlled by the pore throat size distribution and the balance between capillarity and gravity. We develop a theoretical model that captures the evolution of immiscible gravity currents and predicts the maximum migration distance. Our work suggests that capillary pinning and capillary blunting exert an important control on finite-release gravity currents in the context of CO2 sequestration in deep saline aquifers. Gravity driven flow of a buoyant, nonwetting fluid (air) over a dense, wetting fluid (propylene glycol). Starting with a vertical interface between the fluids, the flow first undergoes a lock-exchange process. The process models a finite release problem after the dense fluid hits the left boundary. In contrast to finite release of a miscible current that spreads indefinitely, spreading of an immiscible

  2. Pore-scale modeling of moving contact line problems in immiscible two-phase flow

    NASA Astrophysics Data System (ADS)

    Kucala, Alec; Noble, David; Martinez, Mario

    2016-11-01

    Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  3. Experimental development of processes to produce homogenized alloys of immiscible metals, phase 3

    NASA Technical Reports Server (NTRS)

    Reger, J. L.

    1976-01-01

    An experimental drop tower package was designed and built for use in a drop tower. This effort consisted of a thermal analysis, container/heater fabrication, and assembly of an expulsion device for rapid quenching of heated specimens during low gravity conditions. Six gallium bismuth specimens with compositions in the immiscibility region (50 a/o of each element) were processed in the experimental package: four during low gravity conditions and two under a one gravity environment. One of the one gravity processed specimens did not have telemetry data and was subsequently deleted for analysis since the processing conditions were not known. Metallurgical, Hall effect, resistivity, and superconductivity examinations were performed on the five specimens. Examination of the specimens showed that the gallium was dispersed in the bismuth. The low gravity processed specimens showed a relatively uniform distribution of gallium, with particle sizes of 1 micrometer or less, in contrast to the one gravity control specimen. Comparison of the cooling rates of the dropped specimens versus microstructure indicated that low cooling rates are more desirable.

  4. Non-traditional stable isotope behaviors in immiscible silica-melts in a mafic magma chamber

    PubMed Central

    Zhu, Dan; Bao, Huiming; Liu, Yun

    2015-01-01

    Non-traditional stable isotopes have increasingly been applied to studies of igneous processes including planetary differentiation. Equilibrium isotope fractionation of these elements in silicates is expected to be negligible at magmatic temperatures (δ57Fe difference often less than 0.2 per mil). However, an increasing number of data has revealed a puzzling observation, e.g., the δ57Fe for silicic magmas ranges from 0‰ up to 0.6‰, with the most positive δ57Fe almost exclusively found in A-type granitoids. Several interpretations have been proposed by different research groups, but these have so far failed to explain some aspects of the observations. Here we propose a dynamic, diffusion-induced isotope fractionation model that assumes Si-melts are growing and ascending immiscibly in a Fe-rich bulk magma chamber. Our model offers predictions on the behavior of non-traditional stable isotope such as Fe, Mg, Si, and Li that are consistent with observations from many A-type granitoids, especially those associated with layered intrusions. Diffusion-induced isotope fractionation may be more commonly preserved in magmatic rocks than was originally predicted. PMID:26620121

  5. Non-traditional stable isotope behaviors in immiscible silica-melts in a mafic magma chamber.

    PubMed

    Zhu, Dan; Bao, Huiming; Liu, Yun

    2015-12-01

    Non-traditional stable isotopes have increasingly been applied to studies of igneous processes including planetary differentiation. Equilibrium isotope fractionation of these elements in silicates is expected to be negligible at magmatic temperatures (δ(57)Fe difference often less than 0.2 per mil). However, an increasing number of data has revealed a puzzling observation, e.g., the δ(57)Fe for silicic magmas ranges from 0‰ up to 0.6‰, with the most positive δ(57)Fe almost exclusively found in A-type granitoids. Several interpretations have been proposed by different research groups, but these have so far failed to explain some aspects of the observations. Here we propose a dynamic, diffusion-induced isotope fractionation model that assumes Si-melts are growing and ascending immiscibly in a Fe-rich bulk magma chamber. Our model offers predictions on the behavior of non-traditional stable isotope such as Fe, Mg, Si, and Li that are consistent with observations from many A-type granitoids, especially those associated with layered intrusions. Diffusion-induced isotope fractionation may be more commonly preserved in magmatic rocks than was originally predicted.

  6. Non-traditional stable isotope behaviors in immiscible silica-melts in a mafic magma chamber

    NASA Astrophysics Data System (ADS)

    Zhu, Dan; Bao, Huiming; Liu, Yun

    2015-12-01

    Non-traditional stable isotopes have increasingly been applied to studies of igneous processes including planetary differentiation. Equilibrium isotope fractionation of these elements in silicates is expected to be negligible at magmatic temperatures (δ57Fe difference often less than 0.2 per mil). However, an increasing number of data has revealed a puzzling observation, e.g., the δ57Fe for silicic magmas ranges from 0‰ up to 0.6‰, with the most positive δ57Fe almost exclusively found in A-type granitoids. Several interpretations have been proposed by different research groups, but these have so far failed to explain some aspects of the observations. Here we propose a dynamic, diffusion-induced isotope fractionation model that assumes Si-melts are growing and ascending immiscibly in a Fe-rich bulk magma chamber. Our model offers predictions on the behavior of non-traditional stable isotope such as Fe, Mg, Si, and Li that are consistent with observations from many A-type granitoids, especially those associated with layered intrusions. Diffusion-induced isotope fractionation may be more commonly preserved in magmatic rocks than was originally predicted.

  7. The microstructure and electrical transport properties of immiscible copper-niobium alloy thin films

    SciTech Connect

    Banerjee, Rajarshi; Bose, Sangita; Ayyub, Pushan; Genc, Arda

    2008-02-01

    Mutually immiscible in the solid state, copper and niobium exhibit a relatively strong clustering (phase separating) tendency in the liquid state and can therefore only be alloyed in a highly metastable form: for example, by vapor quenching. We have deposited metastable Cu-Nb alloy thin films with nominal compositions ranging from 5 to 90 at. % Nb by magnetron cosputtering. The microstructure of these films depends strongly on the composition and ranges from coarse-grained solid solutions for Cu-rich and Nb-rich compositions to phase-separated amorphous mixtures when the two elements are in comparable amounts. The crystalline Cu- or Nb-rich compositions exhibit positive temperature coefficients of resistivity (TCR) with the Cu-90 at. % Nb film exhibiting a superconducting transition with (T{sub C}){sub onset}{approx}4.5 K. The amorphous films show high room temperature resistivity, a negative TCR, and composition dependent superconducting transitions. We investigate the relation between the microstructure, phase stability, and the electrical transport properties.

  8. Nanodroplets of immiscible fluid pairs adopt nonspherical shapes

    NASA Astrophysics Data System (ADS)

    Wilemski, Gerald; Hrahsheh, Fawaz

    2015-03-01

    To help understand recent experimental results for nonane/water condensation [Pathak, et al. J. Chem. Phys. 140, 224318 (2014)], the structure of water/nonane nanodroplets was investigated using classical molecular dynamics (MD) simulations of SPC/E water and a unified atom model of nonane. Because nonane and water are essentially immiscible fluids that only partially wet each other, one might expect unusual nanodroplet structures to arise. Indeed, nonspherical, phase-separated Russian Doll (RD) structures were found to occur for these nanodroplets over the entire temperature range studied in the MD simulations, 220K - 300K. An idealized, but realistic lens-on-sphere model for the observed RD structures consists of a spherical nonane lens that partially wets a spherical water droplet. This model was used to analyze the experimental small angle x-ray scattering measurements. The simulated contact angle of nonane on water was found to be quite sensitive to the value of the Lennard-Jones energy parameter ɛOC for the cross-interaction between oxygen and carbon atoms. The standard geometric mean approximation for ɛOCyielded contact angles in the range 70o- 80o, while a 19% increase in ɛOCreduced the simulated contact angle close to the experimental value of 33.6o at 295 K. Supported by NSF Grant No. CBET-1033387.

  9. The immiscibility of InAlN ternary alloy

    PubMed Central

    Zhao, Guijuan; Xu, Xiaoqing; Li, Huijie; Wei, Hongyuan; Han, Dongyue; Ji, Zesheng; Meng, Yulin; Wang, Lianshan; Yang, Shaoyan

    2016-01-01

    We have used two models based on the valence force field and the regular solution model to study the immiscibility of InAlN ternary alloy, and have got the spinodal and binodal curves of InAlN. Analyzing the spinodal decomposition curves, we obtain the appropriate concentration region for the epitaxial growth of the InN-AlN pseudobinary alloy. At a temperature most common for the epitaxial growth of InAlN (1000 K), the solubility of InN is about 10%. Then we introduce the mismatch strain item into the Gibbs free energy, and the effect of different substrates is taken into consideration. Considering Si, Al2O3, InN, GaN, AlN as a substrate respectively, it is found that all the five systems are stabilized with the upper critical solution temperature largely reduced. Finally, InN and GaN are potential substrates for In-rich InAlN, while AlN and GaN substrates are recommended in the Al-rich region. Si and Al2O3 may be ideal substrates for thin InAlN film. PMID:27221345

  10. Cylindrical waves at the interface of viscous immiscible fluids

    NASA Astrophysics Data System (ADS)

    Dasgupta, Ratul; Farsoiya, Palas Kumar

    2016-11-01

    We conduct Navier-Stokes simulations of cylindrical, axisymmetric standing gravity waves at the interface of radially unbounded, immiscible viscous fluids. The fluid motion generated by these oscillations are studied. Results from the numerical solutions are compared to the analytical solution of an integro-differential equation representing the amplitude of motion of the interface. Standing waves are initiated at the interface as zeroth order Bessel's mode at rest i.e. h (r , 0) =H0 1 + ɛJ0 (kr) where H0 is the undisturbed fluid depth in the simulation, chosen to be large enough for deep water approximation to hold. For small initial amplitudes (compared to 2 πk-1), we obtain good agreement with the analytical solution at early times. As we increase initial amplitude, the time period of the first oscillation is found to increase. Diffusion of vorticity from the interface is studied as a function of initial amplitude. We compare our results to the analytical solution obtained from the corresponding planar problem (Prosperetti, 1981). We will discuss these results in the framework of the viscous Cauchy-Poisson (initial-value) problem between two fluids, and also compare our results to the viscous, single fluid case (Miles, 1968). We thank IRCC, IIT Bombay for financial support.

  11. Wettability controls slow immiscible displacement through local interfacial instabilities

    NASA Astrophysics Data System (ADS)

    Jung, Michael; Brinkmann, Martin; Seemann, Ralf; Hiller, Thomas; Sanchez de La Lama, Marta; Herminghaus, Stephan

    2016-11-01

    Immiscible fluid displacement with average front velocities in the capillary-dominated regime is studied in a transparent Hele-Shaw cell with cylindrical posts. Employing various combinations of fluids and wall materials allows us to cover a range of advancing contact angles 46∘≤θa≤180∘ of the invading fluid in our experiments. In parallel, we study the displacement process in particle-based simulations that account for wall wettability. Considering the same arrangement of posts in experiments and simulation, we find a consistent crossover between stable interfacial displacement at θa≲80∘ and capillary fingering at high contact angles θa≳120∘ . The position of the crossover is quantified through the evolution of the interface length and the final saturation of the displaced fluid. A statistical analysis of the local displacement processes demonstrates that the shape evolution of the fluid front is governed by local instabilities as proposed by Cieplak and Robbins for a quasistatic interfacial displacement [Cieplak and Robbins, Phys. Rev. Lett. 60, 2042 (1988), 10.1103/PhysRevLett.60.2042]. The regime of stable front advances coincides with a corresponding region of contact angles where cooperative interfacial instabilities prevail. Capillary fingering, however, is observed only for large θa, where noncooperative instabilities dominate the invasion process.

  12. Immiscibility in the Nickel Ferrite-Zinc Ferrite Spinel Binary

    SciTech Connect

    SE Ziemniak; AR Gaddipati; PC Sander; SB Rice

    2006-06-21

    Immiscibility in the trevorite (NiFe{sub 2}O{sub 4}) - franklinite (ZnFe{sub 2}O{sub 4}) spinel binary is investigated by reacting 1:1:2 molar ratio mixtures of NiO, ZnO and Fe{sub 2}O{sub 3} in a molten salt solvent at temperatures in the range 400-1000 C. Single phase stability is demonstrated down to about 730 C (the estimated consolute solution temperature, T{sub cs}). A miscibility gap/solvus exists below Tcs. The solvus becomes increasingly asymmetric at lower temperatures and extrapolates to n - values = 0.15, 0.8 at 300 C. A thermodynamic analysis, which accounts for changes in configurational and magnetic ordering entropies during cation mixing, predicts solvus phase compositions at room temperature in reasonable agreement with those determined by extrapolation of experimental results. The delay between disappearance of magnetic ordering above T{sub C} = 590 C (for NiFe{sub 2}O{sub 4}) and disappearance of a miscibility gap at T{sub cs} is explained by the persistence of long-range ordering correlations in a quasi-paramagnetic region above T{sub C}.

  13. Immiscibility in the nickel ferrite zinc ferrite spinel binary

    NASA Astrophysics Data System (ADS)

    Ziemniak, S. E.; Gaddipati, A. R.; Sander, P. C.; Rice, S. B.

    2007-08-01

    Immiscibility in the trevorite (NiFe2O4) franklinite (ZnFe2O4) spinel binary is investigated by reacting 1:1:2 molar ratio mixtures of NiO, ZnO and Fe2O3 in a molten salt solvent at temperatures in the range 400 1000 °C. Single phase stability is demonstrated down to about 730 °C (the estimated consolute solution temperature, Tcs). A miscibility gap/solvus exists below Tcs. The solvus becomes increasingly asymmetric at lower temperatures and extrapolates to stoichiometric parameters = 0.15, 0.8 at 300 °C. A thermodynamic analysis, which accounts for changes in configurational and magnetic ordering entropies during cation mixing, predicts solvus phase compositions at room temperature in reasonable agreement with those determined by extrapolation of experimental results. The delay between disappearance of magnetic ordering above TC=590C (for NiFe2O4) and disappearance of a miscibility gap at Tcs is explained by the persistence of long-range ordering correlations in a quasi-paramagnetic region above TC.

  14. Rebound of continuous droplet streams from an immiscible liquid pool

    NASA Astrophysics Data System (ADS)

    Doak, William J.; Laiacona, Danielle M.; German, Guy K.; Chiarot, Paul R.

    2016-05-01

    We report on the rebound of high velocity continuous water droplet streams from the surface of an immiscible oil pool. The droplets have diameters and velocities of less than 90 μm and 15 m/s, respectively, and were created at frequencies up to 60 kHz. The impact and rebound of continuous droplet streams at this scale and velocity have been largely unexplored. This regime bridges the gap between single drop and jet impacts. The impinging droplets create a divot at the surface of the oil pool that had a common characteristic shape across a wide-range of droplet and oil properties. After impact, the reflected droplets maintain the same uniformity and periodicity of the incoming droplets but have significantly lower velocity and kinetic energy. This was solely attributed to the generation of a flow induced in the viscous oil pool by the impacting droplets. Unlike normally directed impact of millimeter-scale droplets with a solid surface, our results show that an air film does not appear to be maintained beneath the droplets during impact. This suggests direct contact between the droplets and the surface of the oil pool. A ballistic failure limit, correlated with the Weber number, was identified where the rebound was suppressed and the droplets were driven through the oil surface. A secondary failure mode was identified for aperiodic incoming streams. Startup effects and early time dynamics of the rebounding droplet stream were also investigated.

  15. Phase Change Effects on Immiscible Flow Displacements in Radial Injection

    NASA Astrophysics Data System (ADS)

    Ahmadlouydarab, Majid; Azaiez, Jalel; Chen, Zhangxin

    2014-11-01

    We report a systematic simulation of immiscible fluid-fluid displacements in radial injection in the presence of phase change. Due to the presence of two fluid-fluid interfaces in the system, a special treatment has been adopted. To track the leading interface position, two highly accurate methods including Level Set and Immersed Interface Method were used, while for locating the trailing interface an energy equation was adopted assuming the existence of a constant thin condensate layer. Dimensional analysis led to three important dimensionless groups including capillary number (Ca), Jacob number (Ja) and viscosity ratios (M) of the three fluids. Simulation results indicate significant influences of these parameters on the development of the instability and the interfacial morphology of fingers. Increasing Ca or M tends to amplify the interfacial instability, fingertip splitting, and results in longer fingers. In contrast, increasing Ja has stabilizing effects due to an increase of the thickness of the condensate layer. On the other hand at lower viscosity ratios as well as lower Ca, because of compensation effects of the phase change, both leading and trailing interfaces are found to be less unstable. Moreover accumulated condensate and oil saturation depletion curves show increasing and decreasing trends, respectively, when the Ca increases. Although viscosity ratio and Ja have similar effects on the accumulated condensate, they do not show any effect on the oil depletion saturation.

  16. Thermally induced collision of droplets in an immiscible outer fluid

    NASA Astrophysics Data System (ADS)

    Davanlou, Ashkan; Kumar, Ranganathan

    2015-05-01

    Micro-total analysis systems (μTAS) have attracted wide attention and are identified as a promising solution for sample transport, filtration, chemical reactions, separation and detection. Despite their popularity, the selection of an appropriate mechanism for droplet transport and coalescence has always been a challenge. This paper investigates the use of Marangoni flow as a mechanism for levitating and transporting droplets on immiscible liquid films at higher speeds than is possible currently. For the first time, we show that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of shape and size on collision outcome are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. In addition, the effect of viscosity on post collision regimes is studied. The findings in this fundamental study can be beneficial to many applications such as welding, drug delivery and microfluidics devices in controlling small droplets and targeting them to various locations.

  17. Thermally induced collision of droplets in an immiscible outer fluid.

    PubMed

    Davanlou, Ashkan; Kumar, Ranganathan

    2015-05-07

    Micro-total analysis systems (μTAS) have attracted wide attention and are identified as a promising solution for sample transport, filtration, chemical reactions, separation and detection. Despite their popularity, the selection of an appropriate mechanism for droplet transport and coalescence has always been a challenge. This paper investigates the use of Marangoni flow as a mechanism for levitating and transporting droplets on immiscible liquid films at higher speeds than is possible currently. For the first time, we show that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of shape and size on collision outcome are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. In addition, the effect of viscosity on post collision regimes is studied. The findings in this fundamental study can be beneficial to many applications such as welding, drug delivery and microfluidics devices in controlling small droplets and targeting them to various locations.

  18. Hot water flushing for immiscible displacement of a viscous NAPL.

    PubMed

    O'Carroll, Denis M; Sleep, Brent E

    2007-05-14

    Thermal remediation techniques, such as hot water flooding, are emerging technologies that have been proposed for the removal of nonaqueous phase liquids (NAPLs) from the subsurface. In this study a combined laboratory and modeling investigation was conducted to determine if hot water flooding techniques would improve NAPL mass removal compared to ambient temperature water flushing. Two experiments were conducted in a bench scale two-dimensional sandbox (55 cmx45 cmx1.3 cm) and NAPL saturations were quantified using a light transmission apparatus. In these immiscible displacement experiments the aqueous phase, at 22 degrees C and 50 degrees C, displaced a zone with initial NAPL saturations on the order of 85%. The interfacial tension and viscosity of the selected light NAPL, Voltesso 35, are strongly temperature-dependent. Experimental results suggest that hot water flooding reduced the size of the high NAPL saturation zone, in comparison to the cold water flood, and yielded greater NAPL mass recovery (75% NAPL removal vs. 64%). Hot water flooding did not, however, result in lower residual NAPL saturations. A numerical simulator was modified to include simultaneous flow of water and organic phases, energy transport, temperature and pressure. Model predictions of mass removal and NAPL saturation profiles compared well with observed behavior. A sensitivity analysis indicates that the utility of hot water flooding improves with the increasing temperature dependence of NAPL hydraulic properties.

  19. Thermally induced collision of droplets in an immiscible outer fluid

    PubMed Central

    Davanlou, Ashkan; Kumar, Ranganathan

    2015-01-01

    Micro-total analysis systems (μTAS) have attracted wide attention and are identified as a promising solution for sample transport, filtration, chemical reactions, separation and detection. Despite their popularity, the selection of an appropriate mechanism for droplet transport and coalescence has always been a challenge. This paper investigates the use of Marangoni flow as a mechanism for levitating and transporting droplets on immiscible liquid films at higher speeds than is possible currently. For the first time, we show that it is possible to realize the natural coalescence of droplets through Marangoni effect without any external stimulation, and deliver the coalesced droplet to a certain destination through the use of surface tension gradients. The effects of shape and size on collision outcome are studied. Regions of coalescence and stretching separation of colliding droplets are delineated based on Weber number and impact number. In addition, the effect of viscosity on post collision regimes is studied. The findings in this fundamental study can be beneficial to many applications such as welding, drug delivery and microfluidics devices in controlling small droplets and targeting them to various locations. PMID:25948547

  20. Characteristic impedance of a microchannel with two immiscible microfluids

    NASA Astrophysics Data System (ADS)

    Jaramillo Raquejo, Daniela

    2014-05-01

    Consider the case of a microcapillary of radius R with two microfluidic immiscible. The micro-capillary region 0 < r < R1 is occupied by the microfluidic less dense and less viscous; while the microcapillary region R1 <0 < R is occupied by the microfluidic more dense and more viscous. Determine the characteristic impedance of the microcapillary in this case when both microfluidics are driven by the same pressure gradient as the boundary condition at the wall of the microcapillary is of the non-Newtonian slip. The Navier Stokes equation is solved for both microfluidic methods using the Laplace transform. The velocity profiles are expressed in terms of Bessel functions. Similarly, the characteristic impedance of the microcapillary is expressed by a complex formula Bessel functions. Obtain the analytical results are important for designing engineering microdevices with applications in pharmaceutical, food engineering, nanotechnology and biotechnology in general in particular. For future research it is interesting to consider the case of boundary conditions with memory effects.

  1. Immiscible displacement in a rough fracture: beyond Darcy's law

    NASA Astrophysics Data System (ADS)

    Pahlavan, A. A.; Cueto-Felgueroso, L.; McKinley, G. H.; Juanes, R.

    2016-12-01

    The interplay between wetting and disorder, as well as the inherent complexity of porous media renders the description of immiscible displacement a daunting task. Nano-scale physics dictates the macroscopic behavior of the moving contact lines, which in turn determines the flow pattern. To shed light on this problem, we conduct experiments on rough radial Hele-Shaw cells and use the results to guide our modeling efforts. We saturate the cell with a highly viscous glycerol, and then inject a less viscous silicone oil at the center of the cell and visualize the displacement patterns. The surfaces are treated to alter their wettability, allowing us to study both drainage (less wetting liquid displacing a more wetting one) and imbibition (opposite of drainage) regimes. Viscous forces tend to destabilize the interfaces, whereas capillary forces play a stabilizing role; however, the disorder in the medium complicates this balance substantially: 1) it leads to heterogeneities in the permeability field and capillary pressure distribution, and 2) it changes the effective wettability of the medium and leads to contact line-pinning and hysteresis. We observe that at high capillary numbers (ratio of viscous forces to capillary forces), the disorder only weakly modulates the patterns, whereas at low capillary numbers, the disorder affects the flow pattern significantly; it leads to preferential flow paths in the drainage regime, and pinning and intermittent avalanche-like behavior in the imbibition regime. Based on these observations, we propose a phase diagram by incorporating the wettability, capillary number, and effective roughness of the medium as the controlling parameters. Inspired by these observations, we construct a thermodynamically-consistent phase-field model, taking the non-hydrodynamic interactions between the liquids and the solid surface into account. Our model goes beyond Darcy's law, which cannot describe the observed unstable displacements, by taking

  2. Electroosmotic flow in a water column surrounded by an immiscible liquid.

    PubMed

    Movahed, Saeid; Khani, Sina; Wen, John Z; Li, Dongqing

    2012-04-15

    In this paper, we conducted numerical simulation of the electroosmotic flow in a column of an aqueous solution surrounded by an immiscible liquid. While governing equations in this case are the same as that in the electroosmotic flow through a microchannel with solid walls, the main difference is the types of interfacial boundary conditions. The effects of electric double layer (EDL) and surface charge (SC) are considered to apply the most realistic model for the velocity boundary condition at the interface of the two fluids. Effects on the flow field of ς-potential and viscosity ratio of the two fluids were investigated. Similar to the electroosmotic flow in microchannels, an approximately flat velocity profile exists in the aqueous solution. In the immiscible fluid phase, the velocity decreases to zero from the interface toward the immiscible fluid phase. The velocity in both phases increases with ς-potential at the interface of the two fluids. The higher values of ς-potential also increase the slip velocity at the interface of the two fluids. For the same applied electric field and the same ς-potential at the interface of the two fluids, the more viscous immiscible fluid, the slower the system moves. The viscosity of the immiscible fluid phase also affects the flatness of the velocity profile in the aqueous solution. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. Fluoride-silicate melt immiscibility and its role in REE ore formation: Evidence from the Strange Lake rare metal deposit, Québec-Labrador, Canada

    NASA Astrophysics Data System (ADS)

    Vasyukova, Olga; Williams-Jones, Anthony E.

    2014-08-01

    Pegmatites and adjacent subsolvus granites (two alkali feldspars) of the Mid-Proterozoic Strange Lake pluton (Québec-Labrador, Canada) host potentially economic concentrations of high field strength elements (HFSE), including the rare earth elements (REE), zirconium and niobium. Previous studies have proposed that these concentrations were the result of a combination of extreme fractionation of a peralkaline granitic magma and later hydrothermal remobilization. However, the recent discovery of melt inclusions which, after heating to 900 or 950 °C, quench to immiscible fluoride and silicate glasses, suggests an additional mechanism of HFSE concentration. Crystallized melt inclusions are common in quartz phenocrysts of the early hypersolvus and transsolvus granite. After heating, four types of inclusions were discerned. Type 1 inclusions quench to a single silicate glass containing a high concentration of Zr, Nb and Ti. Quenching of Type 2 inclusions produces a Zr, Nb, Ti-rich silicate glass containing a globule of calcium-rich fluoride glass with a high concentration of the REE. The third inclusion type is similar to Type 2, except that the calcium-rich fluoride glass contains a globule of REE-fluoride glass (up to 50 wt.% total REE). Type 4 inclusions contain calcium-fluoride glass with multiple silicate globules. We propose that during or soon after emplacement, the early granitic magma exsolved a calcium fluoride melt into which rare earth elements (REE) partitioned preferentially. The conjugate silicate melt was consequently depleted in Ca and the REE, and enriched in Zr, Nb and Ti. Crystallization of the fluoride melt occurred late in the crystallization history of the silicate magma allowing it to accumulate in the volatile-rich residual magma that formed the pegmatites. This played a major role in the extreme enrichment of the pegmatites in Ca, F and REE. Crystallization of the pegmatites proceeded inwards from an outer zone in which feldspars, quartz

  4. Synthesis of new metastable nanoalloys of immiscible metals with a pulse laser technique

    PubMed Central

    Swiatkowska-Warkocka, Zaneta; Pyatenko, Alexander; Krok, Franciszek; Jany, Benedykt R.; Marszalek, Marta

    2015-01-01

    The generation of nanoalloys of immiscible metals is still a challenge using conventional methods. However, because these materials are currently attracting much attention, alternative methods are needed. In this article, we demonstrate a simple but powerful strategy for the generation of a new metastable alloy of immiscible metals. Au1−xNix 3D structures with 56 at% of nickel in gold were successfully manufactured by the pulsed laser irradiation of colloidal nanoparticles. This technology can be used for preparing different metastable alloys of immiscible metals. We hypothesise that this technique leads to the formation of alloy particles through the agglomerations of nanoparticles, very fast heating, and fast cooling/solidification. Thus, we expect that our approach will be applicable to a wide range of inorganic solids, yielding even new metastable solids that fail to be stable in the bulk systems, and therefore do not exist in Nature. PMID:25952016

  5. Experimental liquid line of descent and liquid immiscibility for basalt 70017. [lunar rocks

    NASA Technical Reports Server (NTRS)

    Rutherford, M. J.; Hess, P. C.; Daniel, G. H.

    1974-01-01

    The paper describes one possible liquid line of descent produced for a high-titanium mare basalt composition through an arbitrarily chosen series of partial equilibrium and fractional crystallization experiments on basalt 70017. The liquid line of descent leading to immiscibility at 994 C is characterized by enrichment of FeO, K2O, SiO2, and MnO and depletion of MgO and TiO2 in the residual liquids. The composition of the residual liquid at the onset of immiscibility is ferrobasaltic, and the initial appearance of immiscible liquids in the form of silica-rich spherules is in the vicinity of plagioclase-liquid contacts. The integrated bulk composition of the areas of finely exsolved liquids indicates that the trend of the liquid line of descent is at a small angle to the tie lines joining the two liquids.

  6. Are water-immiscibility and apolarity of the solvent relevant to enzyme efficiency

    SciTech Connect

    Narayan, V.S.; Klibanov, A.M. )

    1993-02-05

    The question of whether the solvent's water-immiscibility is relevant to enzymatic activity was addressed by assaying four different hydrolases (three lipases and one protease) in nine anhydrous solvents of similar hydrophobicities of which four were infinitely miscible with water and five were not. For no enzyme was a jump in activity observed upon a transition from water-miscible to water-immiscible solvents. The relevance of solvent apolarity to enzymatic efficiency was also examined. To this end, three groups of isomeric anhydrous solvents were selected where within each group one solvent was apolar. For none of the four enzymes studied was activity significantly higher in apolar solvents than in their polar counterparts. Thus the authors conclude that often-cited solvent's immiscibility with water and apolarity by themselves are irrelevant to enzymatic activity.

  7. Identification of Gravity-Related Effects on Crystal Growth From Melts With an Immiscibility Gap

    NASA Technical Reports Server (NTRS)

    Kassemi, M.; Sayir, A.; Farmer, S.

    1999-01-01

    This work involves an experimental-numerical approach to study the effects of natural and Marangoni convections on solidification of single crystals from a silicate melt with a liquid-liquid immiscibility gap. Industrial use of crystals grown from silicate melts is becoming increasingly important in electronic, optical, and high temperature structural applications. Even the simplest silicate systems like Al203-SiO2 have had, and will continue to have, a significant role in the development of traditional and advanced ceramics. A unique feature of crystals grown from the silicate systems is their outstanding linear electro-optic properties. They also exhibit exceptionally high optical rotativity. As a result, these crystals are attractive materials for dielectric, optical, and microwave applications. Experimental work in our laboratory has indicated that directional solidification of a single crystal mullite appears to be preceded by liquid-liquid phase separation in the melt. Disruption of the immiscible state results in crystallization of a two phase structure. There is also evidence that mixing in the melt caused by density-driven convection can significantly affect the stability of the immiscible liquid layers and result in poly-crystalline growth. On earth, the immiscible state has only been observed for small diameter crystals grown in float zone systems where natural convection is almost negligible. Therefore, it is anticipated that growth of large single crystals from silicate melts would benefit from microgravity conditions because of the reduction of the natural convective mixing. The main objective of this research is to determine the effects of transport processes on the phase separation in the melt during growth of a single crystal while addressing the following issues: (1) When do the immiscible layers form and are they real?; (2) What are the main physical characteristics of the immiscible liquids?; and (3) How mixing by natural or Marangoni convection

  8. Why are blue zhamanshinites blue? Liquid immiscibility in an impact melt

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Koeberl, Christian

    1991-01-01

    A study of the cause of the coloration of blue zhamanshinites, which are glassy impact melt rocks from the Zhamanshin crater in the USSR are reported. It is found that the blue color results from Rayleigh scattering from spherical, 100 nm-diameter inclusions of a separate Ca-Fe-Mg-P-rich silicate glass. These observations can best be explained by the operation of liquid immiscibility in the zhamanshinite melt, and suggest that liquid immiscibility may have a more general role in impactite evolution.

  9. Characterizing the Use of Ultrasonic Energy in Promoting Uniform Microstructural Dispersions in Immiscible Mixtures

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Fedoseyev, A. I.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Gravity driven separation and preferential wetting precludes uniform microstructural distributions during solidification processing of immiscible, liquid-liquid mixtures. Historically, it is, however, established that liquid/liquid suspensions can be established and maintained by utilizing ultrasound. Following a brief introduction the results of experiments on immiscible mixtures subjected to ultrasonic energy during solidification processing will be compared and evaluated in view of a recently developed mathematical model. The presentation continues by discussion of scaling the model to commercial viability and concludes with the implications of such processing in a microgravity environment.

  10. Characterizing the Use of Ultrasonic Energy in Promoting Uniform Microstructural Dispersions in Immiscible Mixtures

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Fedoseyev, A. I.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Gravity driven separation and preferential wetting precludes uniform microstructural distributions during solidification processing of immiscible, liquid-liquid mixtures. Historically, it is, however, established that liquid/liquid suspensions can be established and maintained by utilizing ultrasound. Following a brief introduction the results of experiments on immiscible mixtures subjected to ultrasonic energy during solidification processing will be compared and evaluated in view of a recently developed mathematical model. The presentation continues by discussion of scaling the model to commercial viability and concludes with the implications of such processing in a microgravity environment.

  11. Characterizing the Use of Ultrasonic Energy in Promoting Uniform Microstructural Dispersions in Immiscible Mixtures

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Fedoseyev, A. I.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Gravity driven separation and preferential wetting precludes uniform microstructural distributions during solidification processing of immiscible, liquid-liquid mixtures. Historically, it is, however, established that liquid/liquid suspensions can be established and maintained by utilizing ultrasound. Following a brief introduction the results of experiments on immiscible mixtures subjected to ultrasonic energy during solidification processing will be compared and evaluated in view of a recently developed mathematical model. The presentation continues by discussion of scaling the model to commercial viability and concludes with the implications of such processing in a microgravity environment.

  12. Solidification Processing of Immiscible Liquids in the Presence of Applied Ultrasonic Energy

    NASA Technical Reports Server (NTRS)

    Kim, Shinwood; Grugel, R. N.

    2000-01-01

    Uniform microstructural development during solidification of immiscible liquids on Earth is hampered by inherent density differences between the phases. Microgravity processing minimizes settling but segregation still occurs due to gravity independent wetting and coalescence phenomena. Experiments with the transparent organic, metal analogue, succinonitrile-glycerol system were conducted in conjunction with applied ultrasonic energy. The processing parameters associated with this technique have been evaluated in view of optimizing dispersion uniformity. Experimental results to evaluate microstructural phase distributions, based on other liquid-liquid immiscibility systems, will also be presented.

  13. Layered interfaces between immiscible liquids studied by density-functional theory and molecular-dynamics simulations

    NASA Astrophysics Data System (ADS)

    Geysermans, P.; Elyeznasni, N.; Russier, V.

    2005-11-01

    We present a study of the structure in the interface between two immiscible liquids by density-functional theory and molecular-dynamics calculations. The liquids are modeled by Lennard-Jones potentials, which achieve immiscibility by supressing the attractive interaction between unlike particles. The density profiles of the liquids display oscillations only in a limited part of the simple liquid-phase diagram (ρ,T). When approaching the liquid-vapor coexistence, a significant depletion appears while the layering behavior of the density profile vanishes. By analogy with the liquid-vapor interface and the analysis of the adsorption this behavior is suggested to be strongly related to the drying transition.

  14. The role of liquid-liquid immiscibility and crystal fractionation in the genesis of carbonatite magmas: insights from Kerimasi melt inclusions

    NASA Astrophysics Data System (ADS)

    Guzmics, Tibor; Zajacz, Zoltán; Mitchell, Roger H.; Szabó, Csaba; Wälle, Markus

    2015-02-01

    We have reconstructed the compositional evolution of the silicate and carbonate melt, and various crystalline phases in the subvolcanic reservoir of Kerimasi Volcano in the East African Rift. Trace element concentrations of silicate and carbonate melt inclusions trapped in nepheline, apatite and magnetite from plutonic afrikandite (clinopyroxene-nepheline-perovskite-magnetite-melilite rock) and calciocarbonatite (calcite-apatite-magnetite-perovskite-monticellite-phlogopite rock) show that liquid immiscibility occurred during the generation of carbonatite magmas from a CO2-rich melilite-nephelinite magma formed at relatively high temperatures (1,100 °C). This carbonatite magma is notably more calcic and less alkaline than that occurring at Oldoinyo Lengai. The CaO-rich (32-41 wt%) nature and alkali-"poor" (at least 7-10 wt% Na2O + K2O) nature of these high-temperature (>1,000 °C) carbonate melts result from strong partitioning of Ca (relative to Mg, Fe and Mn) in the immiscible carbonate and the CaO-rich nature (12-17 wt%) of its silicate parent (e.g., melilite-nephelinite). Evolution of the Kerimasi carbonate magma can result in the formation of natrocarbonatite melts with similar composition to those of Oldoinyo Lengai, but with pronounced depletion in REE and HFSE elements. We suggest that this compositional difference results from the different initial parental magmas, e.g., melilite-nephelinite at Kerimasi and a nephelinite at Oldoinyo Lengai. The difference in parental magma composition led to a significant difference in the fractionating mineral phase assemblage and the element partitioning systematics upon silicate-carbonate melt immiscibility. LA-ICP-MS analysis of coeval silicate and carbonate melt inclusions provides an opportunity to infer carbonate melt/silicate melt partition coefficients for a wide range of elements. These data show that Li, Na, Pb, Ca, Sr, Ba, B, all REE (except Sc), U, V, Nb, Ta, P, Mo, W and S are partitioned into the carbonate

  15. Quaternary extrusive calciocarbonatite volcanism on Brava Island (Cape Verde): A nephelinite-carbonatite immiscibility product

    NASA Astrophysics Data System (ADS)

    Mourão, Cyntia; Mata, João; Doucelance, Régis; Madeira, José; da Silveira, António Brum; Silva, Luís C.; Moreira, Manuel

    2010-02-01

    The Cape Verde volcanic archipelago, located in the oceanic portion of the African plate some 500 km west of the Senegal coast, is renowned for the occurrence of carbonatites on at least 5 of its 10 islands. In this study we report the occurrence of about twenty new small outcrops of extrusive carbonatites on Brava Island (64 km 2), the south-westernmost island of the archipelago. These new occurrences are studied from geological, petrographic, mineral chemistry and whole rock (elemental and isotopic) geochemical points of view, allowing for a discussion of their petrogenesis and emphasising their geological and geochemical peculiarities in the context of the Cape Verde carbonatites. Most of the extrusive carbonatitic formations correspond to pyroclastic rocks, comprising magmatic and/or phreatomagmatic ash and lapilli fall deposits and one probable pyroclastic flow. Lava flows occur at one locality. The predominance of pyroclastic facies demonstrates the significant explosivity of these magmas characterised by very low viscosity. Independent of the modes of emplacement, all samples are calciocarbonatites and exhibit a remarkable compositional uniformity, considering that they represent several different eruptions and present a wide geographical dispersion. Brava extrusive carbonatites belong to the younger (probable Holocene - Pleistocene) volcanic sequence of the island. This feature is unique in the context of Cape Verde geology, because in the other islands (including Brava) of the archipelago carbonatites are commonly assigned to the basal complexes, having formed during a fairly early stage of the emerged evolution of volcanic construction. Compared with the older intrusive sövitic rocks occurring at Middle Unit of Brava Island, extrusive facies are more iron and manganese rich and yield higher contents of trace elements like Ba, Th, U, Nb, Pb and REE, but somewhat lower Sr abundances. New initial Sr and Nd isotope data (0.703557-0.703595 and 0

  16. Morphology Evolution of Polypropylene in Immiscible Polymer Blends for Fabrication of Nanofibers

    USDA-ARS?s Scientific Manuscript database

    Immiscible blends of cellulose acetate butyrate (CAB) and isotactic polypropylenes (iPPs) with different melting index were extruded through a two-strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios by controlling the drawing speed. The morphologies of iPP fibers e...

  17. Morphological development of polypropylene in immiscible blends with cellulose acetate butyrate

    USDA-ARS?s Scientific Manuscript database

    Isotactic polypropylenes (iPP) with different melt flow indexes were melt blended with cellulose acetate butyrate (CAB) and then prepared into microspheres or nanofibers following a novel process of producing well dispersed CAB/iPP immiscible blends and subsequent removal of the CAB matrix. The morp...

  18. Effects of crucible wetting during solidification of immiscible Pb-Zn

    NASA Technical Reports Server (NTRS)

    Degroh, Henry C., III; Probst, Hubert B.

    1988-01-01

    Many industrial uses for liquid phase miscibility gap alloys are proposed. However, the commercial production of these alloys into useful ingots with a reasonable amount of homogeneity is arduous because of their immiscibility in the liquid state. In the low-g environment of space gravitational settling forces are abated, thus solidification of an immiscible alloys with a uniform distribution of phases becomes feasible. Elimination of gravitational settling and coalescence processes in low-g also makes possible the study of other separation and coarsening mechanisms. Even with gravitational separation forces reduced, many low-g experiments have resulted in severely segregated structures. The segregation in many cases was due to preferential wetting of the crucible by one of the immiscible liquids. The objective was to analyze the wetting behavior of Pb-Zn alloys on various crucible materials in an effort to identify a crucible in which the fluid flow induced by preferential wetting is minimized. It is proposed that by choosing the crucible for a particular alloy so that the difference in surface energy between the solid and two liqud phases is minimized, the effects of preferential wetting can be diminished and possibly avoided. Qualitative experiments were conducted and have shown the competitive wetting behavior of the immiscible Pb-Zn system and 13 different crucible materials.

  19. Effects of crucible wetting during solidification of immiscible Pb-Zn alloys

    NASA Technical Reports Server (NTRS)

    De Groh, H. C., III; Probst, H. B.

    1989-01-01

    Many industrial uses for liquid phase miscibility gap alloys are proposed. However, the commercial production of these alloys into useful ingots with a reasonable amount of homogeneity is arduous because of their immiscibility in the liquid state. In the low-g environment of space gravitational settling forces are abated, thus solidification of an immiscible alloy with a uniform distribution of phases becomes feasible. Elimination of gravitational settling and coalescence processes in low-g also makes possible the study of other separation and coarsening mechanisms. Even with gravitational separation forces reduced, many low-g experiments have resulted in severely segregated structures. The segregation in many cases was due to preferential wetting of the crucible by one of the immiscible liquids. The objective was to analyze the wetting behavior of Pb-Zn alloys on various crucible materials in an effort to identify a crucible in which the fluid flow induced by preferential wetting is minimized. It is proposed that by choosing the crucible for a particular alloy so that the difference in surface energy between the solid and two liquid phases is minimized, the effects of preferential wetting can be diminished and possibly avoided. Qualitative experiments were conducted and have shown the competitive wetting behavior of the immiscible Pb-Zn system and 13 different crucible materials.

  20. The Impact of Composition on the Physical Properties and Evaporative Mass Transfer of a PCE-Diesel Immiscible Liquid

    PubMed Central

    Carroll, Kenneth C.; Taylor, Renee; Gray, Evan; Brusseau, Mark L.

    2010-01-01

    The impact of immiscible-liquid composition on mass transfer between immiscible liquid and vapor was evaluated for a complex mixture of chlorinated solvents and petroleum hydrocarbons. A mixture of PCE (tetrachloroethene) and diesel was discovered at a site in Tucson, Arizona. Partitioning of PCE into a previously spilled diesel free product has been observed, with resultant concentrations of PCE above 15% by weight. The density, viscosity, surface tension, and interfacial tension were measured for PCE-diesel mixtures with PCE fractions from 7 to 32%, and the results indicated that immiscible-liquid composition did impact the physical properties of the PCE-diesel mixture. Comparison of gas and aqueous phase partitioning results to predictions based on Raoult's Law indicated that the immiscible liquid behaved essentially as an ideal mixture. Flow-cell experiments were conducted to characterize PCE removal from the PCE-diesel mixture via vapor extraction. The effluent concentrations for the experiment conducted with free-phase immiscible liquid were comparable to equilibrium values. Conversely, they were significantly lower for the experiment wherein a residual saturation of immiscible liquid was distributed within sand. These results suggest that evaporation for the latter experiment was constrained by rate-limited mass transfer, which was attributed to dilution effects associated with a nonuniform immiscible-liquid distribution. PMID:18926630

  1. Plagiogranites as late-stage immiscible liquids in ophiolite and mid-ocean ridge suites - An experimental study

    NASA Technical Reports Server (NTRS)

    Dixon, S.; Rutherford, M. J.

    1979-01-01

    A study of relationships between basic and acidic rocks was made by fractionating primitive basalt at low pressure anhydrous conditions at various fugacities. Fractionally crystallized basalt became increasingly enriched in iron which became silicate liquid immiscible, producing Fe-enriched basaltic and granitic liquids. The latter is similar to plagiogranites found in mid-oceanic rift (MOR) regions, showing that silicate liquid immiscibility could be the petrogenic process which produces plagiogranites in some MOR regions and ophiolites. The major problem in considering plagiogranites as products of silicate liquid immiscibility is absence of any description of the Fe-enriched conjugate liquid in the ophiolite or MOR literature, and the identification of this magma is essential for a definite case of silicate liquid immiscibility.

  2. Calculation of Liquid-Solid Interfacial Free Energy in Pb-Cu Binary Immiscible System

    NASA Astrophysics Data System (ADS)

    Li, Hong-shan; Zhou, Sheng-gang; Cao, Yong

    2016-11-01

    Based on the solid-liquid interfacial free energy theory of the complex Warren binary & pseudo-binary system and through the simplification of it by taking Pb-Cu binary system as an example, the physical model for it in binary immiscible system can be obtained. Next, its thermodynamic formula is derived to obtain a theoretical formula that only contains two parameters, and comparisons are made with regard to γSL calculated values and experimental values of MPE (multiphase equilibrium method) under several kinds of temperatures. As manifested in the outcomes, the improved physical model and theoretical formula will become not only easy to understand but also simple for calculation (the calculated value of γSL depends on two parameters, i.e. temperature and percentage composition of Cu atom). It can be treated as the foundation of application for the γSL calculation of liquid-solid interfacial free energy in other immiscible systems.

  3. Macroscopic surface tension in a lattice Bhatnagar-Gross-Krook model of two immiscible fluids

    NASA Astrophysics Data System (ADS)

    Halliday, I.; Thompson, S. P.; Care, C. M.

    1998-01-01

    We present a method by which an interface generating algorithm, similar to that of earlier lattice Boltzmann models of immiscible fluids, may be extended to a two component, two-speed two-dimensional (D2), nine-link (Q9) lattice Bhatnagar-Gross-Krook fluid. For two-dimensional, microcurrent-free planar interfaces between the two immiscible fluids we derive expressions for static interfacial tensions and interfacial distributions of the two fluids. Extending our analysis to curved interfaces, we propose a scheme for incorporating the influence of interfacial microcurrents that is based upon general symmetry arguments and is correct to second order in lattice velocity. The analysis demonstrates that the interfacial microcurrents have only second-order influence upon the macroscopic behavior of the model. We find good agreement between our calculations and simulation results based on the microcurrent stream function and surface tension results from the pressure tensor or Laplace law.

  4. Effect of using miscible and immiscible healing agent on solid state self-healing system

    NASA Astrophysics Data System (ADS)

    Makenan, Siti Mastura; Jamil, Mohd Suzeren Md.

    2014-09-01

    The aim of this study is to identify the effect of using various healing agent which are miscible; poly(bisphenol-A-co-epichlorohydrin), and immiscible; poly(ethylene-co-acetate) and poly(ethylene-co-acrylic acid), on self-healing resin system. The specimens were analysed by Fourier-transform Infrared Spectrometer (FTIR), Dynamic Mechanical Thermal Analysis (DMTA), and izod test. Optical image of the sample morphology was observed using optical microscope. Healing efficiencies (HE) were evaluated using izod test. The concept of healing recovery was proved based on the use of miscible and immiscible healing agent. From the results, it can be concluded that the healable resin with miscible healing agent has the highest HE within the third healing cycle.

  5. Self-Forming Interlocking Interfaces on the Immiscible Polymer Bilayers via Gelation-Mediated Phase Separation.

    PubMed

    Zhou, Xiaozhuang; Ma, Guoqiang; Zhao, Huaixia; Cui, Jiaxi

    2017-09-01

    Gelation-mediated phase separation is applied to prepare immiscible polymer bilayer films with an interlocking interface structure. Polymer systems consisting of copolymer of urea and polydimethylsiloxane and epoxy are selected to demonstrate the feasibility. When the epoxy fraction exceeds 25 wt%, well-defined bilayer structures self-form by a one-pot casting method in which the phase separation state is fixed by an evaporation-induced gelation. Microscopy studies of the resulting bilayers clearly reveal that interlocking structures form during the bilayer films construct. The interlocking structures lead to an enhanced interfacial adhesion and higher fracture energy. The current strategy might offer a facile way to in situ create an interlocking interface between immiscible polymer systems. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Mussel adhesion-employed water-immiscible fluid bioadhesive for urinary fistula sealing.

    PubMed

    Kim, Hyo Jeong; Hwang, Byeong Hee; Lim, Seonghye; Choi, Bong-Hyuk; Kang, Seok Ho; Cha, Hyung Joon

    2015-12-01

    Urinary fistulas, abnormal openings of a urinary tract organ, are serious complications and conventional management strategies are not satisfactory. For more effective and non-invasive fistula repair, fluid tissue adhesives or sealants have been suggested. However, conventional products do not provide a suitable solution due to safety problems and poor underwater adhesion under physiological conditions. Herein, we proposed a unique water-immiscible mussel protein-based bioadhesive (WIMBA) exhibiting strong underwater adhesion which was employed by two adhesion strategies of marine organisms; 3,4-dihydroxy-l-phenylalanine (DOPA)-mediated strong adhesion and water-immiscible coacervation. The developed biocompatible WIMBA successfully sealed ex vivo urinary fistulas and provided good durability and high compliance. Thus, WIMBA could be used as a promising sealant for urinary fistula management with further expansion to diverse internal body applications.

  7. Melt immiscibility in Apollo 15 KREEP - Origin of Fe-rich mare basalts

    NASA Technical Reports Server (NTRS)

    Hollister, L. S.; Crawford, M. L.

    1977-01-01

    Silicate liquid immiscibility (SLI) is investigated in terms of chemistry and occurrence in two KREEP-rich Apollo 15 basalts. The two samples have different cooling histories but the same composition. In the first sample, SLI occurred at the time of 58% crystallization. In the second sample, SLI occurred after 20% had crystallized. It is noted that SLI could be initiated as soon as plagioclase (out of a total composition which also included zircon, FeS, SiO2, whitlockite, and ilmenite) alone had crystallized. Attention is given to Fe-rich immiscible melts, and it is suggested that SLI may play an important role in the formation of the source regions of Fe-rich mare basalts. The analytical technique used for the assays was an energy dispersive analysis system with a resolution of 167 eV.

  8. Carbonate-silicate melt immiscibility, REE mineralising fluids, and the evolution of the Lofdal Intrusive Suite, Namibia

    NASA Astrophysics Data System (ADS)

    Bodeving, Sarah; Williams-Jones, Anthony E.; Swinden, Scott

    2017-01-01

    The Lofdal Intrusive Suite, Namibia, consists of calcio-carbonatite and silica-undersaturated alkaline intrusive rocks ranging in composition from phono-tephrite to phonolite (and nepheline syenite). The most primitive of these rocks is the phono-tephrite, which, on the basis of its Y/Ho and Nb/Ta ratios, is interpreted to have formed by partial melting of the mantle. Roughly linear trends in major and trace element contents from phono-tephrite to phonolite and nepheline syenite indicate that the latter two rock types evolved from the phono-tephrite by fractional crystallisation. The nepheline syenite, however, has a lower rare earth element (REE) content than the phonolite. The carbonatite has a primitive mantle-normalised REE profile roughly parallel to that of the silica-undersaturated alkaline igneous rocks, although the absolute REE concentrations are higher. Like the phono-tephrite, it also has a mantle Y/Ho ratio. However, the Nb/Ta and Zr/Hf ratios are significantly higher. Moreover, the carbonatite displays strong negative Ta, Zr and Hf anomalies on spidergrams, whereas the silicate rocks display positive anomalies for these elements. Significantly, this behaviour is predicted by the corresponding carbonatite-silicate melt partition coefficients, as is the behaviour of the REE. Based on these observations, we interpret the carbonatite to represent an immiscible liquid that exsolved from the phono-tephrite or possibly the phonolite melt. The result was a calcio-carbonatite that is enriched in the heavy REE (HREE) relative to most other carbonatites. Fluids released from the corresponding magma are interpreted to have been the source of the REE mineralisation that is currently the target of exploration.

  9. Oxygen isotope partitioning between immiscible silicate melts with H2O, P and S

    NASA Astrophysics Data System (ADS)

    Lester, Gregory W.; Kyser, T. K.; Clark, Alan H.

    2013-05-01

    Differences between the δ18O values of immiscible Si- and Fe-rich melts in the systems Fe2SiO4-Fe3O4-KAlSi2O6-SiO2, Fe3O4-KAlSi2O6-SiO2, and Fe3O4-Fe2O3-KAlSi2O6-SiO2, with H2O, H2O + P or H2O + S have been determined in isothermal, isobaric experiments at 1100 and 1200 °C and 200 MPa. The Δ18O values for conjugate Fe2SiO4-Fe3O4-KAlSi2O6-SiO2 + H2O and, Fe3O4-KAlSi2O6-SiO2·KAlSi2O6-SiO2 + H2O melts are only 0.4-0.6‰ and do not differ significantly from those for anhydrous melts of similar composition. The Δ18O values for melts with added H2O + P or S are more variable, ranging from 0.0 to 0.8‰. Partitioning of 18O between the immiscible melts is 0.6-1‰ less than the partitioning reported for melt-mineral and mineral-mineral pairs. The partitioning of 18O in the network modifier-bearing immiscible melts is not controlled by the relative degree of polymerization in the melts or fO2. The upper limit of the range of Δ18O values (<1‰), and the variation in the δ18O values of conjugate melts that occurs with the inclusion of network modifying constituents, suggest that in some cases, oxygen isotope ratios might be useful to distinguish lithologies evolved from coexisting immiscible silicate melts, from lithologies that have evolved by crystal fractionation only.

  10. Structures of immiscible Al-In alloys solidified under microgravity conditions

    NASA Technical Reports Server (NTRS)

    Potard, C.

    1981-01-01

    Four samples of the immiscible Al-In system having monotectic and hypermonotectic compositions were solidified under microgravity during the NASA-SPAR IX flight of January 20th, 1981. The experimental thermal and physico-chemical conditions actually achieved have been analysed. Radiographic and metallographic observations of the samples show a non-regular dispersed primary phase inside the monotectic matrix. These observations are commented on the basis of capillarity and solidification aspects.

  11. Buoyant displacement flow of immiscible fluids in inclined ducts: A theoretical approach

    NASA Astrophysics Data System (ADS)

    Hasnain, A.; Alba, K.

    2017-05-01

    We study the buoyant displacement flow of two immiscible Newtonian fluids in an inclined duct (two-dimensional channel) theoretically. The fluids may have different viscosities. The displacing fluid is denser than the displaced one, i.e., a density-unstable configuration. For simplicity, the fluids are assumed to behave as neutrally wetting in the vicinity of duct walls. The small diameter-to-length ratio of the duct considered (δ ≪1 ) has been used as the perturbation parameter in developing a lubrication model (negligible inertia). Appropriate Navier-slip conditions have been applied at the walls to overcome contact-line problem singularity. The lubrication model developed has then been numerically solved using a robust total variation diminishing finite difference scheme. Completely different flow patterns have been observed compared to the miscible limit. Fluids immiscibility is found to cause a capillary ridge in the vicinity of the displacing front, which diminishes as the surface tension is increased. For small values of surface tension parameter, the fluids immiscibility is found to decelerate the advancement of interpenetrating heavy and light layers. More efficient displacement (less fingering within the displacing layer) has been observed at small density differences and when the displacing fluid is more viscous than the displaced one. The limit of zero imposed velocity corresponding to the exchange flow has further been considered in the lubrication model. An interesting jump in the interface height occurs close to the vicinity of the gate region due to the immiscibility, which has been similarly reported in other recent computational works. Detailed mathematical notes on the similarity solution of the flow at long times are moreover provided. Investigating the short-time dynamics of the flow reveals the dominance of diffusive surface tension effects over buoyancy.

  12. Theoretical and experimental investigation on separation of two immiscible liquids using hydrocyclones

    SciTech Connect

    Bohnet, M.; Harms, G.

    1996-12-31

    For a reliable design of hydrocyclones for the separation of two immiscible liquids the correct calculation of pressure drop and separation efficiency is necessary. To determine the separation process correctly, a possible droplet breakup within the hydrocyclone due to shear forces and/or turbulence has to be considered. It is shown, that the real droplet size distribution which is responsible for the separation process can be calculated depending on fluid flow parameters. 5 figs.

  13. Immiscible iron- and silica-rich liquids in the Upper Zone of the Bushveld Complex

    NASA Astrophysics Data System (ADS)

    Fischer, Lennart A.; Wang, Meng; Charlier, Bernard; Namur, Olivier; Roberts, R. James; Veksler, Ilya V.; Cawthorn, R. Grant; Holtz, François

    2016-06-01

    The Bushveld Complex (South Africa) is the largest layered intrusion on Earth and plays a considerable role in our understanding of magmatic differentiation and ore-forming processes. In this study, we present new geochemical data for apatite-hosted multiphase inclusions in gabbroic cumulates from the Bushveld Upper Zone. Inclusions re-homogenized at high-temperature (1060-1100 °C) display a range of compositions in each rock sample, from iron-rich (35 wt.% FeOtot; 28 wt.% SiO2) to silica-rich (5 wt.% FeOtot; 65 wt.% SiO2). This trend is best explained by an immiscible process and trapping of contrasted melts in apatite crystals during progressive cooling along the binodal of a two-liquid field. The coexistence of both Si-rich and Fe-rich immiscible melts in single apatite grains is used to discuss the ability of immiscible melts to segregate from each other, and the implications for mineral and bulk cumulate compositions. We argue that complete separation of immiscible liquids did not occur, resulting in crystallization of similar phases from both melts but in different proportions. However, partial segregation in a crystal mush and the production of contrasting phase proportions from the Fe-rich melt and the Si-rich melt can be responsible for the cyclic evolution from melanocratic (Fe-Ti-P-rich) to leucocratic (plagioclase-rich) gabbros which is commonly observed in the Upper Zone of the Bushveld Complex where it occurs at a vertical scale of 50 to 200 m.

  14. A Full View of the Segregation Evolution in Al-Bi Immiscible Alloy

    NASA Astrophysics Data System (ADS)

    Lu, Wenquan; Zhang, Shuguang; Zhang, Wei; Hu, Qiaodan; Yu, Jianding; Fu, Yanan; Li, Jianguo

    2017-06-01

    Using synchrotron radiography, in this study, we caught a full view of the segregation evolution of Al-10 wt pct Bi immiscible alloy during solidification. We provide the direct experimental evidence of surface segregation prior to liquid decomposition. And the Bi enrichment at the bottom part should come from melt flow rather than Soret effect. The Marangoni effect and Stokes effect dominate in separate stages in solidifying Al-Bi alloy. Further, the size distribution of Bi droplets obeys Gaussian distribution.

  15. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy

    NASA Astrophysics Data System (ADS)

    Zhai, W.; Wang, B. J.; Liu, H. M.; Hu, L.; Wei, B.

    2016-11-01

    The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures.

  16. Gas Separation Membranes Derived from High-Performance Immiscible Polymer Blends Compatibilized with Small Molecules.

    PubMed

    Panapitiya, Nimanka P; Wijenayake, Sumudu N; Nguyen, Do D; Huang, Yu; Musselman, Inga H; Balkus, Kenneth J; Ferraris, John P

    2015-08-26

    An immiscible polymer blend comprised of high-performance copolyimide 6FDA-DAM:DABA(3:2) (6FDD) and polybenzimidazole (PBI) was compatibilized using 2-methylimidazole (2-MI), a commercially available small molecule. Membranes were fabricated from blends of 6FDD:PBI (50:50) with and without 2-MI for H2/CO2 separations. The membranes demonstrated a matrix-droplet type microstructure as evident with scanning electron microscopy (SEM) imaging where 6FDD is the dispersed phase and PBI is the continuous phase. In addition, membranes with 2-MI demonstrated a uniform microstructure as observed by smaller and more uniformly dispersed 6FDD domains in contrast to 6FDD:PBI (50:50) blend membranes without 2-MI. This compatibilization effect of 2-MI was attributed to interfacial localization of 2-MI that lowers the interfacial energy similar to a surfactant. Upon the incorporation of 2-MI, the H2/CO2 selectivity improved remarkably, compared to the pure blend, and surpassed the Robeson's upper bound. To our knowledge, this is the first report of the use of a small molecule to compatibilize a high-performance immiscible polymer blend. This approach could afford a novel class of membranes in which immiscible polymer blends can be compatibilized in an economical and convenient fashion.

  17. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy.

    PubMed

    Zhai, W; Wang, B J; Liu, H M; Hu, L; Wei, B

    2016-11-14

    The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures.

  18. Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy

    PubMed Central

    Zhai, W.; Wang, B. J.; Liu, H. M.; Hu, L.; Wei, B.

    2016-01-01

    The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures. PMID:27841283

  19. A chemical approach toward low temperature alloying of immiscible iron and molybdenum metals

    SciTech Connect

    Nazir, Rabia; Ahmed, Sohail; Mazhar, Muhammad; Akhtar, Muhammad Javed; Siddique, Muhammad; Khan, Nawazish Ali; Shah, Muhammad Raza; Nadeem, Muhammad

    2013-11-15

    Graphical abstract: - Highlights: • Low temperature pyrolysis of [Fe(bipy){sub 3}]Cl{sub 2} and [Mo(bipy)Cl{sub 4}] homogeneous powder. • Easy low temperature alloying of immiscible metals like Fe and Mo. • Uniform sized Fe–Mo nanoalloy with particle size of 48–68 nm. • Characterization by EDXRF, AFM, XRPD, magnetometery, {sup 57}Fe Mössbauer and impedance. • Alloy behaves as almost superparamagnetic obeying simple –R(CPE)– circuit. - Abstract: The present research is based on a low temperature operated feasible method for the synthesis of immiscible iron and molybdenum metals’ nanoalloy for technological applications. The nanoalloy has been synthesized by pyrolysis of homogeneous powder precipitated, from a common solvent, of the two complexes, trisbipyridineiron(II)chloride, [Fe(bipy){sub 3}]Cl{sub 2}, and bipyridinemolybedenum(IV) chloride, [Mo(bipy)Cl{sub 4}], followed by heating at 500 °C in an inert atmosphere of flowing argon gas. The resulting nanoalloy has been characterized by using EDXRF, AFM, XRD, magnetometery, {sup 57}Fe Mössbauer and impedance spectroscopies. These results showed that under provided experimental conditions iron and molybdenum metals, with known miscibility barrier, alloy together to give (1:1) single phase material having particle size in the range of 48–66 nm. The magnetism of iron is considerably reduced after alloy formation and shows its trend toward superparamagnetism. The designed chemical synthetic procedure is equally feasible for the fabrication of other immiscible metals.

  20. Liquid immiscibility in a CTGS (Ca3TaGa3Si2O14) melt

    NASA Astrophysics Data System (ADS)

    Nozawa, Jun; Zhao, Hengyu; Koyama, Chihiro; Maeda, Kensaku; Fujiwara, Kozo; Koizumi, Haruhiko; Uda, Satoshi

    2016-11-01

    Although many studies have indicated that Ca3TaGa3Si2O14 (CTGS) grows congruently from a stoichiometric melt when using the Czochralski (Cz) technique, the occurrence of a secondary phase during growth when using the micro-pulling down (μ-PD) technique has been reported. We have examined the detailed growth mechanism of μ-PD grown CTGS as well as its congruency. Differential thermal analysis (DTA) at an elevated temperature up to 1650 °C shows no peaks associated with the presence of a secondary phase, whereas a secondary phase related peak was detected at an elevated temperature up to 1490 °C with the same heating rate. Back-scattered electron images (BEIs) revealed the occurrence of Ca3Ta2Ga4O14 (CTG) as a secondary phase. The secondary phase appears at the very early stage of growth, which is not possible to explain by a eutectic reaction. The experimental results suggest that liquid immiscibility was present in the melt at around 1490 °C during the growth of s-CTGS. Liquid immiscibility produces Si-rich and Si-poor melts, from which different phases with different compositions are solidified. The μ-PD technique poses a more static environment in the melt than that of Cz technique due to low melt convection and the lack of stirring, which enables liquid immiscibility to emerge.

  1. Numerical simulation of immiscible viscous fingering using adaptive unstructured meshes

    NASA Astrophysics Data System (ADS)

    Adam, A.; Salinas, P.; Percival, J. R.; Pavlidis, D.; Pain, C.; Muggeridge, A. H.; Jackson, M.

    2015-12-01

    Displacement of one fluid by another in porous media occurs in various settings including hydrocarbon recovery, CO2 storage and water purification. When the invading fluid is of lower viscosity than the resident fluid, the displacement front is subject to a Saffman-Taylor instability and is unstable to transverse perturbations. These instabilities can grow, leading to fingering of the invading fluid. Numerical simulation of viscous fingering is challenging. The physics is controlled by a complex interplay of viscous and diffusive forces and it is necessary to ensure physical diffusion dominates numerical diffusion to obtain converged solutions. This typically requires the use of high mesh resolution and high order numerical methods. This is computationally expensive. We demonstrate here the use of a novel control volume - finite element (CVFE) method along with dynamic unstructured mesh adaptivity to simulate viscous fingering with higher accuracy and lower computational cost than conventional methods. Our CVFE method employs a discontinuous representation for both pressure and velocity, allowing the use of smaller control volumes (CVs). This yields higher resolution of the saturation field which is represented CV-wise. Moreover, dynamic mesh adaptivity allows high mesh resolution to be employed where it is required to resolve the fingers and lower resolution elsewhere. We use our results to re-examine the existing criteria that have been proposed to govern the onset of instability.Mesh adaptivity requires the mapping of data from one mesh to another. Conventional methods such as consistent interpolation do not readily generalise to discontinuous fields and are non-conservative. We further contribute a general framework for interpolation of CV fields by Galerkin projection. The method is conservative, higher order and yields improved results, particularly with higher order or discontinuous elements where existing approaches are often excessively diffusive.

  2. Tin-carbon clusters and the onset of microscopic level immiscibility: Experimental and computational study.

    PubMed

    Bernstein, J; Landau, A; Zemel, E; Kolodney, E

    2015-09-21

    We report the experimental observation and computational analysis of the binary tin-carbon gas phase species. These novel ionic compounds are generated by impact of C60(-) anions on a clean tin target at some kiloelectronvolts kinetic energies. Positive Sn(m)C(n)(+) (m = 1-12, 1 ≤ n ≤ 8) ions were detected mass spectrometrically following ejection from the surface. Impact induced shattering of the C60(-) ion followed by sub-surface penetration of the resulting atomic carbon flux forces efficient mixing between target and projectile atoms even though the two elements (Sn/C) are completely immiscible in the bulk. This approach of C60(-) ion beam induced synthesis can be considered as an effective way for producing novel metal-carbon species of the so-called non-carbide forming elements, thus exploring the possible onset of molecular level miscibility in these systems. Sn2C2(+) was found to be the most abundant carbide cluster ion. Its instantaneous formation kinetics and its measured kinetic energy distribution while exiting the surface demonstrate a single impact formation/emission event (on the sub-ps time scale). Optimal geometries were calculated for both neutral and positively charged species using Born-Oppenheimer molecular dynamics for identifying global minima, followed by density functional theory (DFT) structure optimization and energy calculations at the coupled cluster singles, doubles and perturbative triples [CCSD(T)] level. The calculated structures reflect two distinct binding tendencies. The carbon rich species exhibit polyynic/cummulenic nature (tin end capped carbon chains) while the more stoichiometrically balanced species have larger contributions of metal-metal bonding, sometimes resulting in distinct tin and carbon moieties attached to each other (segregated structures). The Sn2C(n) (n = 3-8) and Sn2C(n)(+) (n = 2-8) are polyynic/cummulenic while all neutral Sn(m)C(n) structures (m = 3-4) could be described as small tin clusters (dimer

  3. Tin-carbon clusters and the onset of microscopic level immiscibility: Experimental and computational study

    NASA Astrophysics Data System (ADS)

    Bernstein, J.; Landau, A.; Zemel, E.; Kolodney, E.

    2015-09-01

    We report the experimental observation and computational analysis of the binary tin-carbon gas phase species. These novel ionic compounds are generated by impact of C60 - anions on a clean tin target at some kiloelectronvolts kinetic energies. Positive SnmCn+ (m = 1-12, 1 ≤ n ≤ 8) ions were detected mass spectrometrically following ejection from the surface. Impact induced shattering of the C60 - ion followed by sub-surface penetration of the resulting atomic carbon flux forces efficient mixing between target and projectile atoms even though the two elements (Sn/C) are completely immiscible in the bulk. This approach of C60 - ion beam induced synthesis can be considered as an effective way for producing novel metal-carbon species of the so-called non-carbide forming elements, thus exploring the possible onset of molecular level miscibility in these systems. Sn2C2+ was found to be the most abundant carbide cluster ion. Its instantaneous formation kinetics and its measured kinetic energy distribution while exiting the surface demonstrate a single impact formation/emission event (on the sub-ps time scale). Optimal geometries were calculated for both neutral and positively charged species using Born-Oppenheimer molecular dynamics for identifying global minima, followed by density functional theory (DFT) structure optimization and energy calculations at the coupled cluster singles, doubles and perturbative triples [CCSD(T)] level. The calculated structures reflect two distinct binding tendencies. The carbon rich species exhibit polyynic/cummulenic nature (tin end capped carbon chains) while the more stoichiometrically balanced species have larger contributions of metal-metal bonding, sometimes resulting in distinct tin and carbon moieties attached to each other (segregated structures). The Sn2Cn (n = 3-8) and Sn2Cn+ (n = 2-8) are polyynic/cummulenic while all neutral SnmCn structures (m = 3-4) could be described as small tin clusters (dimer, trimer, and tetramer

  4. Complex nanoprecipitate structures induced by irradiation in immiscible alloy systems

    NASA Astrophysics Data System (ADS)

    Shu, Shipeng; Bellon, P.; Averback, R. S.

    2013-04-01

    We investigate the fundamentals of compositional patterning induced by energetic particle irradiation in model A-B substitutional binary alloys using kinetic Monte Carlo simulations. The study focuses on a type of nanostructure that was recently observed in dilute Cu-Fe and Cu-V alloys, where precipitates form within precipitates, a morphology that we term “cherry-pit” structures. The simulations show that the domain of stability of these cherry-pit structures depends on the thermodynamic and kinetic asymmetry between the A and B elements. In particular, both lower solubilities and diffusivities of A in B compared to those of B in A favor the stabilization of these cherry-pit structures for A-rich average compositions. The simulation results are rationalized by extending the analytic model introduced by Frost and Russell for irradiation-induced compositional patterning so as to include the possible formation of pits within precipitates. The simulations indicate also that the pits are dynamical structures that undergo nearly periodic cycles of nucleation, growth, and absorption by the matrix.

  5. MASS-REMOVAL AND MASS-FLUX-REDUCTION BEHAVIOR FOR IDEALIZED SOURCE ZONES WITH HYDRAULICALLY POORLY-ACCESSIBLE IMMISCIBLE LIQUID

    SciTech Connect

    Brusseau, M. L.; Difilippo, Erica L.; marble, justin C.; Oostrom, Mart

    2008-04-01

    A series of flow-cell experiments was conducted to investigate aqueous dissolution and mass-removal behavior for systems wherein immiscible liquid was non-uniformly distributed in physically heterogeneous source zones. The study focused specifically on characterizing the relationship between mass flux reduction and mass removal for systems for which immiscible liquid is poorly accessible to flowing water. Two idealized scenarios were examined, one wherein immiscible liquid at residual saturation exists within a lower-permeability unit residing in a higher-permeability matrix, and one wherein immiscible liquid at higher saturation (a pool) exists within a higher-permeability unit adjacent to a lower-permeability unit. The results showed that significant reductions in mass flux occurred at relatively moderate mass-removal fractions for all systems. Conversely, minimalmass flux reduction occurred until a relatively large fraction of mass (>80%) was removed for the control experiment, which was designed to exhibit ideal mass removal. In general, mass flux reduction was observed to follow an approximately one-to-one relationship with mass removal. Two methods for estimating mass-flux-reduction/mass-removal behavior, one based on system-indicator parameters (ganglia-to-pool ratio) and the other a simple mass-removal function, were used to evaluate the measured data. The results of this study illustrate the impact of poorly accessible immiscible liquid on mass-removal and mass-flux processes, and the difficulties posed for estimating mass-flux-reduction/mass-removal behavior.

  6. Capillary pinning and blunting of immiscible gravity currents in porous media

    NASA Astrophysics Data System (ADS)

    Zhao, Benzhong; MacMinn, Christopher W.; Huppert, Herbert E.; Juanes, Ruben

    2014-09-01

    Gravity-driven flows in the subsurface have attracted recent interest in the context of geological carbon dioxide (CO2) storage, where supercritical CO2 is captured from the flue gas of power plants and injected underground into deep saline aquifers. After injection, the CO2 will spread and migrate as a buoyant gravity current relative to the denser, ambient brine. Although the CO2 and the brine are immiscible, the impact of capillarity on CO2 spreading and migration is poorly understood. We previously studied the early time evolution of an immiscible gravity current, showing that capillary pressure hysteresis pins a portion of the macroscopic fluid-fluid interface and that this can eventually stop the flow. Here we study the full lifetime of such a gravity current. Using tabletop experiments in packings of glass beads, we show that the horizontal extent of the pinned region grows with time and that this is ultimately responsible for limiting the migration of the current to a finite distance. We also find that capillarity blunts the leading edge of the current, which contributes to further limiting the migration distance. Using experiments in etched micromodels, we show that the thickness of the blunted nose is controlled by the distribution of pore-throat sizes and the strength of capillarity relative to buoyancy. We develop a theoretical model that captures the evolution of immiscible gravity currents and predicts the maximum migration distance. By applying this model to representative aquifers, we show that capillary pinning and blunting can exert an important control on gravity currents in the context of geological CO2 storage.

  7. Carbonatitic and granitic melts produced under conditions of primary immiscibility during anatexis in the lower crust

    NASA Astrophysics Data System (ADS)

    Ferrero, Silvio; Wunder, Bernd; Ziemann, Martin A.; Wälle, Markus; O'Brien, Patrick J.

    2016-11-01

    Carbonatites are peculiar magmatic rocks with mantle-related genesis, commonly interpreted as the products of melting of CO2-bearing peridotites, or resulting from the chemical evolution of mantle-derived magmas, either through extreme differentiation or secondary immiscibility. Here we report the first finding of anatectic carbonatites of crustal origin, preserved as calcite-rich polycrystalline inclusions in garnet from low-to-medium pressure migmatites of the Oberpfalz area, SW Bohemian Massif (Central Europe). These inclusions originally trapped a melt of calciocarbonatitic composition with a characteristic enrichment in Ba, Sr and LREE. This interpretation is supported by the results of a detailed microstructural and microchemical investigation, as well as re-melting experiments using a piston cylinder apparatus. Carbonatitic inclusions coexist in the same cluster with crystallized silicate melt inclusions (nanogranites) and COH fluid inclusions, suggesting conditions of primary immiscibility between two melts and a fluid during anatexis. The production of both carbonatitic and granitic melts during the same anatectic event requires a suitable heterogeneous protolith. This may be represented by a sedimentary sequence containing marble lenses of limited extension, similar to the one still visible in the adjacent central Moldanubian Zone. The presence of CO2-rich fluid inclusions suggests furthermore that high CO2 activity during anatexis may be required to stabilize a carbonate-rich melt in a silica-dominated system. This natural occurrence displays a remarkable similarity with experiments on carbonate-silicate melt immiscibility, where CO2 saturation is a condition commonly imposed. In conclusion, this study shows how the investigation of partial melting through melt inclusion studies may unveil unexpected processes whose evidence, while preserved in stiff minerals such as garnet, is completely obliterated in the rest of the rock due to metamorphic re

  8. Controlling of immiscible liquids fluid in a capillary reactor - from continuous to segmented flow

    NASA Astrophysics Data System (ADS)

    Matyushkin, L. B.; Mbwahnche, R. C.; Ryzhov, O. A.

    2016-11-01

    Experimental variation of the droplets form in the flow of immiscible fluids in a capillary with the inner diameter of 0,9 mm is presented. The possibility of the transition from continuous to segmented flow by varying the velocity of precursors and carrier liquids is demonstrated. It is shown that the rate of variation of one precursor in respect to other makes it possible to vary the ratio of mixing components. Simulation results for Ψ-shaped mixer in COMSOL Multiphysics software are also presented.

  9. Macroscopic laws for immiscible two-phase flow in porous media: Results From numerical experiments

    NASA Astrophysics Data System (ADS)

    Rothman, Daniel H.

    1990-06-01

    Flow through porous media may be described at either of two length scales. At the scale of a single pore, fluids flow according to the Navier-Stokes equations and the appropriate boundary conditions. At a larger, volume-averaged scale, the flow is usually thought to obey a linear Darcy law relating flow rates to pressure gradients and body forces via phenomenological permeability coefficients. Aside from the value of the permeability coefficient, the slow flow of a single fluid in a porous medium is well-understood within this framework. The situation is considerably different, however, for the simultaneous flow of two or more fluids: not only are the phenomenological coefficients poorly understood, but the form of the macroscopic laws themselves is subject to question. I describe a numerical study of immiscible two-phase flow in an idealized two-dimensional porous medium constructed at the pore scale. Results show that the macroscopic flow is a nonlinear function of the applied forces for sufficiently low levels of forcing, but linear thereafter. The crossover, which is not predicted by conventional models, occurs when viscous forces begin to dominate capillary forces; i.e., at a sufficiently high capillary number. In the linear regime, the flow may be described by the linear phenomenological law ui = ΣjLijfj, where the flow rate ui of the ith fluid is related to the force fj applied to the jth fluid by the matrix of phenomenological coefficients Lij which depends on the relative concentrations of the two fluids. The diagonal terms are proportional to quantities commonly referred to as "relative permeabilities." The cross terms represent viscous coupling between the two fluids; they are conventionally assumed to be negligible and require special experimental procedures to observe in a laboratory. In contrast, in this numerical study the cross terms are straightforward to measure and are found to be of significant size. The cross terms are additionally observed to

  10. Ensemble distribution for immiscible two-phase flow in porous media

    NASA Astrophysics Data System (ADS)

    Savani, Isha; Bedeaux, Dick; Kjelstrup, Signe; Vassvik, Morten; Sinha, Santanu; Hansen, Alex

    2017-02-01

    We construct an ensemble distribution to describe steady immiscible two-phase flow of two incompressible fluids in a porous medium. The system is found to be ergodic. The distribution is used to compute macroscopic flow parameters. In particular, we find an expression for the overall mobility of the system from the ensemble distribution. The entropy production at the scale of the porous medium is shown to give the expected product of the average flow and its driving force, obtained from a black-box description. We test numerically some of the central theoretical results.

  11. Non-axisymmetric shapes of a rotating drop in an immiscible system

    NASA Technical Reports Server (NTRS)

    Wang, T. G.; Tagg, R.; Cammack, L.; Croonquist, A. P.

    1982-01-01

    The nonaxisymmetric shapes of a rotating drop in an immiscible system were studied. Five basic families of shapes (axisymmetric, two-lobed, three-lobed, four-lobed, and toroidal) were observed. The sequence (axisymmetric to two-lobed to three-lobed to four-lobed to toroidal) seems to be linked to increasing spin-up velocity. For the axisymmetric case, direct comparisons of experiments with the theory of a free rotating drop were surprisingly good the equatorial area differs from theory by only 30%. Furthermore, the non-axisymmetric shapes are in good qualitative agreement with the theory, although the theory does not address the presence of an outer fluid.

  12. Solidification Processing of Immiscible Liquids in the Presence of Applied Ultrasonic Energy

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Fedoseyev, A. I.; Kim, S.

    2001-01-01

    Uniform microstructural distribution during solidification of immiscible liquids (e.g., oil and water; aluminum and lead) on Earth is hampered by inherent density differences between the phases. Microgravity processing minimizes settling but segregation still occurs due to gravity independent wetting and coalescence phenomena. Experiments with the transparent organic, metal analogue, succinonitrile-glycerol system were conducted in conjunction with applied ultrasonic energy. The processing parameters associated with this technique have been evaluated in view of optimizing dispersion uniformity. Characterization of the experimental results in terms of a modeling effort will also be presented,

  13. Solid-Solution Alloying of Immiscible Ru and Cu with Enhanced CO Oxidation Activity.

    PubMed

    Huang, Bo; Kobayashi, Hirokazu; Yamamoto, Tomokazu; Matsumura, Syo; Nishida, Yoshihide; Sato, Katsutoshi; Nagaoka, Katsutoshi; Kawaguchi, Shogo; Kubota, Yoshiki; Kitagawa, Hiroshi

    2017-03-24

    We report on novel solid-solution alloy nanoparticles (NPs) of Ru and Cu that are completely immiscible even above melting point in bulk phase. Powder X-ray diffraction, scanning transmission electron microscopy, and energy-dispersive X-ray measurements demonstrated that Ru and Cu atoms were homogeneously distributed in the alloy NPs. Ru0.5Cu0.5 NPs demonstrated higher CO oxidation activity than fcc-Ru NPs, which are known as one of the best monometallic CO oxidation catalysts.

  14. Melt inclusion evidence of second immiscibility within a magma derived non-silicate phase (Mt Vesuvius)

    NASA Astrophysics Data System (ADS)

    Fulignati, P.; Kamenetsky, V.; Marianelli, P.; Sbrana, A.

    2003-04-01

    Processes of melt immiscibility occurring during late magmatic differentiation play important role in the generation of many magmatic-hydrothermal ore deposits and may activate and control the style of volcanic eruptions. The exsolution of a non-silicate, volatile-rich phase from the phonolitic magma occurred at the peripheral parts of the 79AD Vesuvius magma chamber. The results of our work suggest that this immiscible phase can further experience another unmixing event that occurs in essentially "post-magmatic" environment. Heating/cooling experiments were carried out on the cogenetic multiphase (clear daughter crystals + vapour bubble(s) + interstial liquid) inclusions, hosted in K-feldspar of cognate felsic xenoliths, representative of rocks in the peripheral parts of the magma chamber. During heating, solid phases begin to dissolve at about 150^oC and melt completely at 530^oC. These low temperatures of melting argue for a non-silicate composition of daughter minerals, and thus bulk inclusion content. The remaining vapour bubble dissolves at 880^oC. During subsequent cooling, vapour bubble nucleates at 785^oC and increases in size. Unmixing of at least two melt phases occurs instantaneously at 500^oC in all studied inclusions. Globules of one melt float freely in the matrix of another melt, change their shape and size, coalesce and split apart continuously down to 100--150^oC. The movements of globules slow down with decreasing temperature until final solidification at 40--50^oC. The similarity of observed phase transformations inside inclusions suggests their homogeneous trapping at magmatic temperatures. By analogy with results of the study of xenoliths from the Vesuvius 472AD eruption (Fulignati et al., 2001) we interpret unmixed phases as globules of the Na-K chloride melt set in the matrix of Ca-carbonate melt. We infer that immiscibility between low viscosity, highly fugitive non-silicate melts may significantly influence partitioning of metals

  15. A new insight into interfaces of immiscible binary polymer blends from the free volume approach

    NASA Astrophysics Data System (ADS)

    Ramya, P.; Meghala, D.; Pasang, T.; Raj, J. M.; Chandrashekara, M. N.; Ranganathaiah, C.

    2012-06-01

    The interface width in an immiscible (PVC/PS) polymer blend is determined using hydrodynamic interaction parameter (α) derived from free volume data measured using Positron lifetime spectrometer. CONTIN program has been employed to get the free volume hole size distribution. A new definition of interface width is presented, which originates from the Kirkwood-Riseman theory and friction coefficient as per Stokes equation. Friction at the interface of a binary blend decides how close the surfaces come or stay farther resulting in narrow or broad interface width respectively.

  16. Instabilities of an immiscible reactive micellar interface in a Hele-Shaw cell

    NASA Astrophysics Data System (ADS)

    Niroobakhsh, Zahra; Litman, Matthew; Belmonte, Andrew

    2016-11-01

    We present the case of a micellar reaction involving two immiscible fluids, which results in the growth of a thin viscoelastic layer between them. A Hele-Shaw cell is initially filled with different oils, including oleic acid, which acts as a cosurfactant. The oil is displaced by an aqueous solution of the surfactant cetylpyridinium chloride. A rich variety of viscous fingering patterns are observed, which are different from classic Saffman-Taylor patterns. We discuss how they change with concentration, surfactant injection rate and type of oil. We also measure the viscoelastic properties of this material using an interfacial rheometer.

  17. Solidification Processing of Immiscible Liquids in the Presence of Applied Ultrasonic Energy

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.; Fedoseyev, A. I.; Kim, S.

    2001-01-01

    Uniform microstructural distribution during solidification of immiscible liquids (e.g., oil and water; aluminum and lead) on Earth is hampered by inherent density differences between the phases. Microgravity processing minimizes settling but segregation still occurs due to gravity independent wetting and coalescence phenomena. Experiments with the transparent organic, metal analogue, succinonitrile-glycerol system were conducted in conjunction with applied ultrasonic energy. The processing parameters associated with this technique have been evaluated in view of optimizing dispersion uniformity. Characterization of the experimental results in terms of a modeling effort will also be presented,

  18. Flow of two immiscible fluids in a periodically constricted tube: Transitions to stratified, segmented, churn, spray, or segregated flow

    NASA Astrophysics Data System (ADS)

    Fraggedakis, D.; Kouris, Ch.; Dimakopoulos, Y.; Tsamopoulos, J.

    2015-08-01

    We study the flow of two immiscible, Newtonian fluids in a periodically constricted tube driven by a constant pressure gradient. Our volume-of-fluid algorithm is used to solve the governing equations. First, the code is validated by comparing its predictions to previously reported results for stratified and pulsing flow. Then, it is used to capture accurately all the significant topological changes that take place. Initially, the fluids have a core-annular arrangement, which is found to either remain the same or change to a different arrangement depending on the fluid properties, the pressure driving the flow, or the flow geometry. The flow-patterns that appear are the core-annular, segmented, churn, spray, and segregated flow. The predicted scalings near pinching of the core fluid concur with similarity predictions and earlier numerical results [I. Cohen et al., "Two fluid drop snap-off problem: Experiments and theory," Phys. Rev. Lett. 83, 1147-1150 (1999)]. Flow-pattern maps are constructed in terms of the Reynolds and Weber numbers. Our result provides deeper insights into the mechanism of the pattern transitions and is in agreement with previous studies on core-annular flow [Ch. Kouris and J. Tsamopoulos, "Core-annular flow in a periodically constricted circular tube, I. Steady state, linear stability and energy analysis," J. Fluid Mech. 432, 31-68 (2001) and Ch. Kouris et al., "Comparison of spectral and finite element methods applied to the study of interfacial instabilities of the core-annular flow in an undulating tube," Int. J. Numer. Methods Fluids 39(1), 41-73 (2002)], segmented flow [E. Lac and J. D. Sherwood, "Motion of a drop along the centreline of a capillary in a pressure-driven flow," J. Fluid Mech. 640, 27-54 (2009)], and churn flow [R. Y. Bai et al., "Lubricated pipelining—Stability of core annular-flow. 5. Experiments and comparison with theory," J. Fluid Mech. 240, 97-132 (1992)].

  19. Surrogate immiscible liquid pairs with refractive indexes matchable over a wide range of density and viscosity ratios

    NASA Astrophysics Data System (ADS)

    Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

    2015-08-01

    In liquid-liquid flows, use of optical diagnostics is limited by interphase refractive index mismatch, which leads to optical distortion and complicates data interpretation, and sometimes also by opacity. Both problems can be eliminated using a surrogate pair of immiscible index-matched transparent liquids, whose density and viscosity ratios match corresponding ratios for the original liquid pair. We show that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables, least-squares fitted to index and density and to the logarithm of kinematic viscosity, were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0 °C over a range of pressure (allowing water-liquid CO2 behavior at inconveniently high pressure to be simulated by 1-bar experiments), and for water-crude oil and water-trichloroethylene (avoiding opacity and toxicity problems, respectively), each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and mass spectrometry and elemental analysis show that no component of either phase has significant interphase solubility. Finally, procedures are described for iteratively reducing the residual index mismatch in surrogate solution pairs prepared on the basis of approximate polynomial fits to experimental data, and for systematically dealing with nonzero interphase solubility.

  20. Immiscible Systems

    ERIC Educational Resources Information Center

    Eckelmann, Jens; Luning, Ulrich

    2013-01-01

    layers of liquids. The setup of both demonstrations is such that one homogeneous layer in a multiphasic mixture separates into two new layers upon shaking. The solvents used are methanol, toluene, petroleum ether or "n"-pentane, silicone oil, perfluoroheptanes,…

  1. Immiscible Systems

    ERIC Educational Resources Information Center

    Eckelmann, Jens; Luning, Ulrich

    2013-01-01

    layers of liquids. The setup of both demonstrations is such that one homogeneous layer in a multiphasic mixture separates into two new layers upon shaking. The solvents used are methanol, toluene, petroleum ether or "n"-pentane, silicone oil, perfluoroheptanes,…

  2. Ripples on a rising bubble through an immiscible two-liquid interface generate numerous micro droplets

    NASA Astrophysics Data System (ADS)

    Uemura, T.; Ueda, Y.; Iguchi, M.

    2010-11-01

    The mass transfer between immiscible two liquid phases can be greatly accelerated by bubbling gas through a reactor (Bird R. B., Stewart W. E. and Lightfoot E. N., Transport Phenomena, 2nd edition (John Wiley and Sons) 2002). Therefore, the physical phenomenon occurring during the passage of a rising bubble through an immiscible two-liquid interface is of particular interest. The passage of the bubble through the oil (upper phase)/water (lower phase) interface starts with an upward lifting of the interface, and the bubble attracts a column of the water phase upwards keeping a film of the water phase around itself. In the present study, a particular remark is given to the influence of different interface tensions retracting the water film, after the water film ruptured, which lays on the interface between air and silicone oil. Unlike the previous studies on the rupture of a single liquid film in a gas which is pulled due to the identical surface tension, this system can form concentric ripples on the outer interface of the water film (oil/water interface) around the bubble due to the weak interface tension. Then, numerous micro water droplets break out from the fully grown ripples.

  3. Adiabatic compressibility of an immiscible molten NaCl-AgI salt mixture

    NASA Astrophysics Data System (ADS)

    Stepanov, V. P.; Tkachev, N. K.; Kulik, N. P.; Peshkina, K. G.

    2016-08-01

    Adiabatic compressibility β of an immiscible 0.5NaCl + 0.5AgI liquid mixture in the immiscibility range is studied experimentally and theoretically using the model of charged hard spheres. The compressibility is calculated by the relationship β = 1/ u 2ρ studied using sound velocity u measured by a pulse method and density ρ determined by hydrostatic weighing. It is shown that the compressibility of the upper phase decreases and that of the lower phase increases when the temperature increases because of the superposition of the effects of the thermal motion of ions and the phase compositions. The temperature dependence of the difference between the compressibilities of the equilibrium phases is described using the empirical equation Δβ = ( T c- T)0.442, which is close to the mean-field theory description. The results of the model calculations adequately reproduce the experimentally observed temperature dependence of the compressibility of the coexisting phases. However, the theoretically predicted critical exponent (1/2) differs from the experimentally determined exponent by 13%. These results are discussed in terms of the nature of chemical bond in silver iodide.

  4. Transparent, immiscible, surrogate liquids with matchable refractive indexes: Increased range of density and viscosity ratios

    NASA Astrophysics Data System (ADS)

    Cadillon, Jérémy; Saksena, Rajat; Pearlstein, Arne J.

    2016-12-01

    By replacing the "heavy" silicone oil used in the oil phase of Saksena, Christensen, and Pearlstein ["Surrogate immiscible liquid pairs with refractive indexes matchable over a wide range of density and viscosity ratios," Phys. Fluids 27, 087103 (2015)] by one with a twentyfold higher viscosity, and replacing the "light" silicone oil in that work by one with a viscosity fivefold lower and a density about 10% lower, we have greatly extended the range of viscosity ratio accessible by index-matching the adjustable-composition oil phase to an adjustable-composition 1,2-propanediol + CsBr + H2O aqueous phase and have also extended the range of accessible density ratios. The new system of index-matchable surrogate immiscible liquids is capable of achieving the density and viscosity ratios for liquid/liquid systems consisting of water with the entire range of light or medium crude oils over the temperature range from 40 °F (4.44 °C) to 200 °F (93.3 °C) and can access the density and viscosity ratios for water with some heavy crude oils over part of the same temperature range. It also provides a room-temperature, atmospheric-pressure surrogate for the liquid CO2 + H2O system at 0 °C over almost all of the pressure range of interest in sub-seabed CO2 sequestration.

  5. Matter-wave solitons in the counterflow of two immiscible superfluids

    NASA Astrophysics Data System (ADS)

    Tsitoura, F.; Achilleos, V.; Malomed, B. A.; Yan, D.; Kevrekidis, P. G.; Frantzeskakis, D. J.

    2013-06-01

    We study formation of solitons induced by counterflows of immiscible superfluids. Our setting is based on a quasi-one-dimensional binary Bose-Einstein condensate, composed of two immiscible components with large and small numbers of atoms in them. Assuming that the “small” component moves with constant velocity, either by itself, or being dragged by a moving trap, and intrudes into the “large” counterpart, the following results are obtained. Depending on the velocity, and on whether the small component moves in the absence or in the presence of the trap, two-component dark-bright solitons, scalar dark solitons, or multiple dark solitons may emerge, the last outcome taking place due to breakdown of the superfluidity. We present two sets of analytical results to describe this phenomenology. In an intermediate velocity regime, where dark-bright solitons form, a reduction of the two-component Gross-Pitaevskii system to an integrable Mel'nikov system is developed, demonstrating that solitary waves of the former are very accurately described by analytically available solitons of the latter. In the high-velocity regime, where the breakdown of the superfluidity induces the formation of dark solitons and multisoliton trains, an effective single-component description, in which a strongly localized wave packet of the “small” component acts as an effective potential for the “large” one, allows us to estimate the critical velocity beyond which the coherent structures emerge in good agreement with the numerical results.

  6. Liquid immiscibility and core-shell morphology formation in ternary Al–Bi–Sn alloys

    SciTech Connect

    Dai, R.; Zhang, J.F.; Zhang, S.G. Li, J.G.

    2013-07-15

    The effects of composition on liquid immiscibility, macroscopic morphology, microstructure and phase transformation in ternary Al–Bi–Sn alloys were investigated. Three types of morphology, the core-shell type, the stochastic droplet type and uniform dispersion type, of Al–Bi–Sn particles prepared by a jet breakup process were distinguished, and the relationships between which were discussed. The phase transformation behaviors of the Al–Bi–Sn alloys were studied by thermal analysis, in agreement with the microstructural observation and microanalysis. The liquid immiscibility and formation of the core-shell morphology in Al–Bi–Sn alloys are easily achieved when the composition lies in the liquid miscibility gap. The particles exhibit a high melting point Al-rich core with a low melting point Sn–Bi-rich solder shell, showing promise for application as high-density electronic packaging materials. - Highlights: • The liquid demixing, morphology and microstructure in Al–Bi–Sn alloys were studied. • Three types of morphology were classified and discussed. • The conditions for formation of the core-shell morphology were obtained. • The phase transition behaviors agree with the microstructure characterization. • The Al/Sn–Bi core-shell particles show promise for use in electronic packaging.

  7. Visual analysis of immiscible displacement processes in porous media under ultrasound effect

    NASA Astrophysics Data System (ADS)

    Naderi, Khosrow; Babadagli, Tayfun

    2011-05-01

    The effect of sonic waves, in particular, ultrasonic radiation, on immiscible displacement in porous media and enhanced oil recovery has been of interest for more than five decades. Attempts were made to investigate the effect through core scale experimental or theoretical models. Visual experiments are useful to scrutinize the reason for improved oil recovery under acoustic waves of different frequency but are not abundant in literature. In this paper, we report observations and analyses as to the effects of ultrasonic energy on immiscible displacement and interaction of the fluid matrix visually in porous media through two-dimensional (2D) sand pack experiments. 2D glass bead models with different wettabilities were saturated with different viscosity oils and water was injected into the models. The experiments were conducted with and without ultrasound. Dynamic water injection experiments were preferred as they had both viscous and capillary forces in effect. The displacement patterns were evaluated both in terms of their shape, size, and the interface characteristics quantitatively and qualitatively to account for the effects of ultrasonic waves on the displacement and the reason for increased oil production under this type of sonic wave. More compact clusters were observed when ultrasonic energy was present in water-wet systems. In the oil-wet cases, more oil was produced after breakthrough when ultrasound was applied and no compact clusters were formed in contrast to the water-wet cases.

  8. Visual analysis of immiscible displacement processes in porous media under ultrasound effect.

    PubMed

    Naderi, Khosrow; Babadagli, Tayfun

    2011-05-01

    The effect of sonic waves, in particular, ultrasonic radiation, on immiscible displacement in porous media and enhanced oil recovery has been of interest for more than five decades. Attempts were made to investigate the effect through core scale experimental or theoretical models. Visual experiments are useful to scrutinize the reason for improved oil recovery under acoustic waves of different frequency but are not abundant in literature. In this paper, we report observations and analyses as to the effects of ultrasonic energy on immiscible displacement and interaction of the fluid matrix visually in porous media through two-dimensional (2D) sand pack experiments. 2D glass bead models with different wettabilities were saturated with different viscosity oils and water was injected into the models. The experiments were conducted with and without ultrasound. Dynamic water injection experiments were preferred as they had both viscous and capillary forces in effect. The displacement patterns were evaluated both in terms of their shape, size, and the interface characteristics quantitatively and qualitatively to account for the effects of ultrasonic waves on the displacement and the reason for increased oil production under this type of sonic wave. More compact clusters were observed when ultrasonic energy was present in water-wet systems. In the oil-wet cases, more oil was produced after breakthrough when ultrasound was applied and no compact clusters were formed in contrast to the water-wet cases.

  9. Preparation and Friction Force Microscopy Measurements of Immiscible, Opposing Polymer Brushes

    PubMed Central

    de Beer, Sissi; Kutnyanszky, Edit; Müser, Martin H.; Vancso, G. Julius

    2014-01-01

    Solvated polymer brushes are well known to lubricate high-pressure contacts, because they can sustain a positive normal load while maintaining low friction at the interface. Nevertheless, these systems can be sensitive to wear due to interdigitation of the opposing brushes. In a recent publication, we have shown via molecular dynamics simulations and atomic force microscopy experiments, that using an immiscible polymer brush system terminating the substrate and the slider surfaces, respectively, can eliminate such interdigitation. As a consequence, wear in the contacts is reduced. Moreover, the friction force is two orders of magnitude lower compared to traditional miscible polymer brush systems. This newly proposed system therefore holds great potential for application in industry. Here, the methodology to construct an immiscible polymer brush system of two different brushes each solvated by their own preferred solvent is presented. The procedure how to graft poly(N-isopropylacrylamide) (PNIPAM) from a flat surface and poly(methyl methacrylate) (PMMA) from an atomic force microscopy (AFM) colloidal probe is described. PNIPAM is solvated in water and PMMA in acetophenone. Via friction force AFM measurements, it is shown that the friction for this system is indeed reduced by two orders of magnitude compared to the miscible system of PMMA on PMMA solvated in acetophenone. PMID:25590429

  10. The mechanism of Bi nanowire growth from Bi/Co immiscible composite thin films.

    PubMed

    Volobuev, Valentine V; Dziawa, Piotr; Stetsenko, Alexander N; Zubarev, Eugene N; Savitskiy, Boris A; Samburskaya, Tatyana A; Reszka, Anna; Story, Tomasz; Sipatov, Alexander Yu

    2012-11-01

    Single crystalline Bi nanowires were grown by extrusion from Bi/Co thin films. The films were obtained by thermal evaporation in high vacuum. The average diameter, length and density of obtained nanowires were 100 nm, 30 microm and 6.5 x 10(5) cm(-2), respectively. The non-catalyzed self-organized process of whisker formation on the surface of immiscible composite thin film was exploited for nanowire growth. It was shown that the whiskers had formed during and after a thin film deposition. The value of residual stresses in a whole thin film coating as well as in its bismuth component was measured using X-ray diffraction technique. It was revealed that local compressive stresses, that had induced the whisker growth, had been formed by a segregation of Bi layers into Bi globules. A simple model of the whisker formation to minimize free energy in the Bi/Co system was proposed taking into account interfacial and elastic deformation energies. The obtained results can be utilized for growing of nanowires of other low-melting-point metals and semiconductors from immiscible composite thin films.

  11. Experimental study on immiscible jet breakup using refractive index matched oil-water pair

    NASA Astrophysics Data System (ADS)

    Xue, Xinzhi; Katz, Joseph

    2016-11-01

    A subsea oil well blowout creates an immiscible crude oil jet. This jet fragments shortly after injection, resulting in generation of a droplet cloud. Detailed understanding of the processes involved is crucial for modeling the fragmentation and for predicting the droplet size distribution. High density of opaque droplets near nozzle limits our ability to visualize and quantify the breakup process. To overcome this challenge, two immiscible fluids: silicone oil and sugar water with the same index of refraction (1.4015) are used as surrogates for crude oil and seawater, respectively. Their ratios of kinematic viscosity (5.64), density (0.83) and interfacial tension are closely matched with those of crude oil and seawater. Distribution of the oil phase is visualized by fluorescent tagging. Both phases are also seeded with particles for simultaneous PIV measurements. The measurements are performed within atomization range of Ohnesorge and Reynolds numbers. Index matching facilitates undistorted view of the phase distribution in illuminated section. Ongoing tests show that the jet surface initially rolls up into Kelvin-Helmholtz rings, followed by development of dispersed phase ligaments further downstream, which then break into droplets. Some of these droplets are re-entrained into the high momentum core, resulting in secondary breakup. As the oil layer and ligaments evolve, they often entrain water, resulting in generation of multiple secondary water droplets encapsulated within the oil droplets. This research is made possible by a Grant from Gulf of Mexico Research Initiative.

  12. Miscible and immiscible experiments on the Rayleigh-Taylor instability using planar laser induced fluorescence visualization

    NASA Astrophysics Data System (ADS)

    Mokler, Matthew; Roberts, Michael; Jacobs, Jeffrey

    2013-11-01

    Incompressible Rayleigh-Taylor instability experiments are presented in which two stratified liquids having Atwood number of 0.2 are accelerated in a vertical linear induction motor driven drop tower. A test sled having only vertical freedom of motion contains the experiment tank and visualization equipment. The sled is positioned at the top of the tower within the linear induction motors and accelerated downward causing the initially stable interface to be unstable and allowing the Rayleigh-Taylor instability to develop. Forced and unforced experiments are conducted using both immiscible and miscible liquid combinations. Forced initial perturbations are produced by vertically oscillating the test sled prior to the start of acceleration. The interface is visualized using a 445 nm laser light source that illuminates a fluorescent dye mixed in one of the fluids. The resulting fluorescent images are recorded using a monochromatic high speed video camera. The laser beam is synchronously swept across the fluorescent fluid, at the frame rate of the camera, exposing a single plane of the interface allowing for the measurement of spike and bubble growth. Comparisons between miscible and immiscible mixing layer distributions are made from the resulting interface concentration profiles.

  13. Microstructure of an immiscible polymer blend and its stabilization effect on amorphous solid dispersions.

    PubMed

    Yang, Ziyi; Nollenberger, Kathrin; Albers, Jessica; Craig, Duncan; Qi, Sheng

    2013-07-01

    This study proposes use of the phase separation of immiscible polymer blends as a formulation approach to improve the stabilization and solubilization of amorphous molecular dispersions of poorly soluble drugs. This approach uses the phase separation and different drug solubilization properties of the two immiscible polymers in the blend to optimize drug loading and stabilization. The model system tested in this study is a EUDRAGIT E PO-PVP-VA 50/50 (w/w) blend loaded with felodipine via hot melt extrusion. The phase separation behavior of the polymer blend and drug loaded polymer blend formulations were characterized using a range of thermal (MTDSC), spectroscopic (ATR-FTIR), and imaging (AFM and thermal transition mapping) techniques. The polymer blend formulations demonstrated superior performance in drug release as well as stabilization against stressed temperature, stressed humidity, and mechanical milling in comparison to the drug-polymer binary systems. This is attributed to the configuration of the phase separated microstructure of the polymer blend formulations where the hydrophilic polymer domains host high concentrations of molecularly dispersed drug which are protected from moisture induced recrystallization on aging by the hydrophobic polymer domains. Additionally drug incorporation as a molecular dispersion in different polymer phases reduces the drug recrystallization tendency on aging under high temperatures and during milling.

  14. Numerical modeling of immiscible two-phase flow in micro-models using a commercial CFD code

    SciTech Connect

    Crandall, Dustin; Ahmadia, Goodarz; Smith, Duane H.

    2009-01-01

    Off-the-shelf CFD software is being used to analyze everything from flow over airplanes to lab-on-a-chip designs. So, how accurately can two-phase immiscible flow be modeled flowing through some small-scale models of porous media? We evaluate the capability of the CFD code FLUENT{trademark} to model immiscible flow in micro-scale, bench-top stereolithography models. By comparing the flow results to experimental models we show that accurate 3D modeling is possible.

  15. Multiple (immiscible) melt phases of mafic composition in Chicxulub impact ejecta from northeastern Mexico: New constraints on target lithologies

    NASA Astrophysics Data System (ADS)

    Schulte, P.; Stinnesbeck, W.; Kontny, A.; Stüben, D.; Kramar, U.; Harting, M.

    2002-12-01

    Proximal ejecta deposits in sections from NE Mexico (Rancho Nuevo, La Sierrita, El Peñon, El Mimbral) have been investigated by backscattered electron imaging, wave-length dispersive electron microprobe analyses, and cathodoluminiscence, in order to characterize target lithologies, and ejecta mixing, fractionation, and distribution mechanisms. Additional investigations included magnetic properties (Kontny et al, this meeting) and trace element analyses (Harting et al, this meeting). Petrological features of these ejecta deposits are extraordinarily well preserved. They consist of mm-cm sized vesiculated spherical to drop-shaped spherules and angular to filamentous (ejecta-) fragments, as well as carbonate clasts, marl clasts, and rare benthic foraminifera floating in a carbonaceous matrix. Occasionally, spherules and fragments show welding-amalgamation features and enclose other components, thus resulting in a foam-like texture. An origin from the Chicxulub impact is suggested by geographical proximity and morphologically similarity to spherules found in other K-T sites in North to Central America and the Atlantic. The far distribution of such coarse-grained, foamy, and fragile ejecta-clasts as well as welding features suggest ignimbrite-like transport mechanisms or nearby secondary impacts. Several silicic ejecta phases have been observed that occur as distinct phases, even within one ejecta particle with textures indicative of liquid immiscibility: (1) Fe- (25-35 wt%), Mg- (10-15 wt%) rich phases with <25 wt% SiO2, altered to chlorite, (2) K- (5-8 wt.%) and Al- (25-30 wt%) rich hydrated glass with 45-50 wt% SiO2, and (3) rare SiO2- (>60 wt%) rich andesitic glasses. In addition to these silicic phases, abundant carbonate characterizes all studied ejecta deposits. It occurs within spherules and fragments and as clasts and globules, and shows textures indicative of either liquid immiscibility and/or quenching (`feathery calcite'). Quenched carbonates are enriched

  16. Effects of nanoclay and conductive carbon black on morphology development in chaotic mixing of immiscible polymers

    NASA Astrophysics Data System (ADS)

    Dharaiya, Dhawal

    Chaotic mixing of immiscible polymer blends has been known to produce morphological features such as lamellas, fibrils and droplets. In this research work, we studied the effect of fillers, such as carbon black (CB) and organically treated nanoclay, on morphology development in an immiscible polymer system, consisting of polyamide 6 (PA6) and polypropylene (PP) in a chaotic mixer. Operating conditions were chosen such that chaotic mixing was widespread inside the mixer. The filler particles were mixed with minor component PP before blending with PA6. It was found that continuous lamellar and fibrillar morphology of PP formed early in mixing produced double percolating conductive networks with only 1 wt% CB particles. The conductive networks sustained their existence even after fibrils broke into droplets. This was attributed to migration of CB particles from the bulk of PP droplets and selective localization at the interfaces of closely spaced PP droplets. It was also found that much smaller PP droplets resulted in the presence of CB particles. Prior reports in literature indicated that organically treated nanoclay particles can act as compatibilizer of immiscible polymer blends, although no study showed that how nanoclay would influence morphology development. In this study, we showed that clay particles helped produce PP droplets of much smaller size and with narrower size distribution due to their direct influence on breakup of PP domains. The clay particles reduced interfacial tension between PP and PA6 phases. Consequently, the PP domains sustained lamellar and fibrillar forms and significantly thin fibrils were formed. These thin fibrils in turn broke rapidly into smaller droplets. It was also found that a large fraction of clay particles migrated into PA6 phase and contained intercalated PA6 chains in their galleries. This indicated that clay particles did not participate in compatibilization in this system. The effect of degradation of surface treatment of

  17. Design and implementation of immiscible carbon dioxide displacement projects (CO/sub 2/ huff-puff) in south Louisiana

    SciTech Connect

    Palmer, F.S.; Landry, R.W.; Bou-Mikael, S.

    1986-01-01

    The CO/sub 2/ Huff-Puff (Immiscible Carbon Dioxide Displacement) process is described including reservoir mechanics. The planning, design, and implementation of the projects including the equipment specifically designed and constructed for these projects are discussed. Case histories of selected projects are included. The paper contains field operations detailing the problems encountered and subsequentially corrected.

  18. Controlled and high throughput fabrication of poly(trimethylene terephthalate) nanofibers via melt extrusion of immiscible blends

    USDA-ARS?s Scientific Manuscript database

    Immiscible blends of cellulose acetate butyrate (CAB) and poly(trimethylene terephthalate) (PTT) were melt extruded through a two strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios. PTT fibers were obtained by removal of the CAB matrix from the drawn extrudates, a...

  19. Fabrication of Tunable Submicro- or Nano-structured Polyethylene Materials form Immiscible Blends with Cellulose Acetate Butyrate

    USDA-ARS?s Scientific Manuscript database

    Low density polyethylene (LDPE) was prepared into micro- or submicro-spheres or nanofibers via melt blending or extrusion of cellulose acetate butyrate (CAB)/LDPE immiscible blends and subsequent removal of the CAB matrix. The sizes of the PE spheres or fibers can be successfully controlled by varyi...

  20. Controlled and high throughput fabrication of poly(trimethylene terphthalate) nanofibers via melt extrusion of immiscible blends

    USDA-ARS?s Scientific Manuscript database

    Immiscible blends of cellulose acetate butyrate (CAB) and poly(trimethylene terephthalate) (PTT) were melt extruded through a two strand rod die. The extrudates were hot-drawn at the die exit at different draw ratios. PTT fibers were obtained by removal of the CAB matrix from the drawn extrudates, a...

  1. Liquid-liquid phase equilibrium and core-shell structure formation in immiscible Al-Bi-Sn alloys

    NASA Astrophysics Data System (ADS)

    Li, Mingyang; Jia, Peng; Sun, Xiaofei; Geng, Haoran; Zuo, Min; Zhao, Degang

    2016-04-01

    In this paper, the liquid-phase separation of ternary immiscible Al45Bi19.8Sn35.2 and Al60Bi14.4Sn25.6 melts was studied with resistivity and thermal analysis methods at different temperature. The resistivity-temperature curves appear abrupt and anomalously change with rising temperature, corresponding to the anomalous and low peak of melting process in DSC curves, indicative of the occurrence of the liquid-phase separation. The anomalous behavior of the resistivity temperature dependence is attributable to concentration-concentration fluctuations. The effect of composition and melt temperature on the liquid-phase separation and core-shell structure formation in immiscible Al-Bi-Sn alloys was studied. The liquid-phase separation and formation of the core-shell structure in immiscible Al-Bi-Sn alloys are readily acquired when the alloy compositions fall into liquid miscibility gap. What's more, the cross-sectional structure changes from irregular, dispersed to core-type shapes under the actions of Marangoni motion with increasing melt temperature. This study provides some clues for the preparation of core-shell microspheres of immiscible Al-Bi-Sn alloys via liquid-phase separation.

  2. Experimental study of liquid immiscibility in the Kiruna-type Vergenoeg iron-fluorine deposit, South Africa

    NASA Astrophysics Data System (ADS)

    Hou, Tong; Charlier, Bernard; Namur, Olivier; Schütte, Philip; Schwarz-Schampera, Ulrich; Zhang, Zhaochong; Holtz, Francois

    2017-04-01

    In this study we experimentally assess whether the bulk composition of the Kiruna-type iron-fluorine Vergenoeg deposit, South Africa (17 wt.% SiO2 and 55 wt.% FeOtot) could correspond to an immiscible Fe-rich melt paired with its host rhyolite. Synthetic powder of the host rhyolite was mixed with mafic end-members (ore rocks) in variable proportions. Experimental conditions were 1-2 kbar and 1010 °C, with a range of H2O and F contents in the starting compositions. Pairs of distinct immiscible liquids occur in experiments saturated with fluorite, under relatively dry conditions, and at oxygen fugacity conditions corresponding to FMQ-1.4 to FMQ+1.8 (FMQ = fayalite-magnetite-quartz solid buffer). The Si-rich immiscible liquids contain 60.9-73.0 wt.% SiO2, 9.1-12.5 wt.% FeOtot, 2.4-4.2 wt.% F, and are enriched in Na2O, K2O and Al2O3. The paired Fe-rich immiscible melts have 41.0-49.5 wt.% SiO2, 20.6-36.1 wt.% FeOtot and 4.5-6.0 wt.% F, and are enriched in MgO, CaO and TiO2. Immiscibility does not develop in experiments performed under water-rich (aH2O > 0.2; a = activity) and/or oxidized (>FMQ+1.8) conditions. In all experiments, solid phases are magnetite, ±fayalite, fluorite and tridymite. Our results indicate that the rocks from the Vergenoeg pipe crystallized in a magma chamber hosting two immiscible silicate melts. Crystallization of the pipe from the Fe-rich melt explains its extreme enrichment in Ca, F and Fe compared to the host rhyolitic rocks. However, its low bulk silica content compared to experimental Fe-rich melts indicates that the pipe formed by remobilization of a mafic crystal mush dominated by magnetite and fayalite. Segregation of evolved residual liquids as well as the conjugate immiscible Si-rich melt produced the host rhyolite. The huge amount of fluorine in Vergenoeg ores (∼12 wt.% F) can hardly be explained by simple crystallization of fluorite from the Fe-rich silicate melt (up to 6 wt.% F at fluorite saturation). Instead, we confirm a

  3. Droplet freezing, docking, and the exchange of immiscible phase and surfactant around frozen droplets.

    PubMed

    Sgro, Allyson E; Chiu, Daniel T

    2010-07-21

    This paper describes a platform for cooling microfluidic chips so as to freeze aqueous droplets flowing in oil. Using a whole-chip cooling chamber, we can control the ambient temperature surrounding a microfluidic chip and induce cooling and freezing inside the channels. When combined with a droplet generation and droplet docking chip, this platform allows for the facile freezing of droplets immobilized in resistance-based docks. Depending on the design and shape of the docks, the frozen droplets can either be trapped stably in the docks or be released because deformed non-frozen aqueous droplets turn spherical when frozen, and thus can become dislodged from the docks. Additionally, using this chamber and chip combination we are able to exchange immiscible phases and surfactants surrounding the frozen droplets. The materials and methods are inexpensive and easily accessible to microfluidics researchers, making this a simple addition to an existing microfluidic platform.

  4. Modeling of Two-Phase Immiscible Flow with Moving Contact Lines

    NASA Astrophysics Data System (ADS)

    Abu Alsaud, Moataz; Soulaine, Cyprien; Riaz, Amir; Tchelepi, Hamdi; Stanford University Collaboration; University of Maryland, College Park Collaboration

    2015-11-01

    A new numerical method based on the implicit interface approach on Cartesian grids is proposed for modeling two-phase immiscible flow with moving contact lines. The reinitialization of level-set function by computing the minimum distance to linearly reconstructed interface to obtain signed distance function is extended to include the contact angle boundary condition. The physics of contact line dynamics is implemented using the Cox-Voinov hydrodynamic theory that efficiently captures the effect of the microscopic contact line region. The numerical method is validated through various examples. Parasitic currents are studied in the case of static and constantly advected parabolic interface intersecting the domain boundary with an imposed contact angle. Moving contact line in the viscous dominated regime is studied and verified through comparison with experiments.

  5. Solvent-free Fabrication of Tissue Engineering Scaffolds with Immiscible Polymer Blends

    PubMed Central

    Ma, Liang; Jiang, Wei; Li, Wei

    2014-01-01

    A completely organic solvent-free fabrication method is developed for tissue engineering scaffolds by gas foaming of immiscible polylactic acid (PLA) and sucrose blends, followed by water leaching. PLA scaffolds with above 90% porosity and 25–200 μm pore size were fabricated. The pore size and porosity was controlled with process parameters including extrusion temperature and foaming process parameters. Dynamic mechanical analysis showed that the extrusion temperature could be used to control the scaffold strength. Both unfoamed and foamed scaffolds were used to culture glioblastoma (GBM) cells M059K. The results showed that the cells grew better in the foamed PLA scaffolds. The method presented in the paper is versatile and can be used to fabricate tissue engineering scaffolds without any residual organic solvents. PMID:24764605

  6. Macroscopic Surface Tension in a Lattice Boltzmann BGK Model of Two Immiscible Fluids.

    NASA Astrophysics Data System (ADS)

    Thompson, S. P.; Halliday, I.; Care, C. M.

    1997-08-01

    We present a method by which an interface generating algorithm, similar to that of earlier lattice Boltzmann models of immisible fluids, may be extended to a two component, two-speed D2Q9 lattice Bhatnagar Gross Krook fluid. For two-dimensional, microcurrent-free planar interfaces between the two immiscible fluids we derive expressions for static interfacial tensions and interfacial distributions of the two fluids. Extending our analysis to curved interfaces we propose a scheme for incorporating the influence of interfacial microcurrents which is based upon general symmetry arguments and is correct to second order in lattice velocity. The analysis demonstrates that the interfacial microcurrents have only second order influence upon the macroscopic behaviour of the model. We find good agreement between our calculations and simulation results based on the microcurrent stream function and surface tension results from the pressure tensor or Laplace law.

  7. Thermo-Gelation of Surface-Modified Polyethylene Microgels from Fragmentation and Immiscible Blends

    NASA Astrophysics Data System (ADS)

    Ling, Gerald H.; Shaw, Montgomery T.

    2008-07-01

    Polyethylene microgels were created by swollen-state grinding and ultrasonic fragmentation of bulk crosslinked polyethylene (XLPE) suspended in squalane, and by the extraction of crosslinked-polyethylene micro-domains from an immiscible blend of polyethylene (PE) and polystyrene (PS). Crosslinking of the polyethylene micro-domains in the blend was achieved by exposure to an electron beam. Suspensions of both microgels in squalane exhibit thermal gelation upon cooling where both G' and G″ increase by up to five-orders in magnitude when probed using small-angle oscillatory shear. We propose that this phenomenon is attributed to weak short-range interactions among the particles whereby surface terminal chains on the microgels can co-crystallize forming inter-particle bonds. However, these interactions are mild enough that the systems may be reverted to its original state by applying higher shear stresses at elevated temperatures.

  8. Vertical vibration dynamics of acoustically levitated drop containing two immiscible liquids

    NASA Astrophysics Data System (ADS)

    Zang, Duyang; Zhai, Zhicong; Li, Lin; Lin, Kejun; Li, Xiaoguang; Geng, Xingguo

    2016-09-01

    We have studied the levitation and oscillation dynamics of complex drops containing two immiscible liquids. Two types of drops, core-shell drop and abnormal-shaped drop, have been obtained depending on the levitation procedures. The oscillation dynamics of the drops have been studied using a high speed camera. It has been found that the oscillation of the abnormal-shaped drop has a longer oscillation period and decays much faster than that of the core-shell drop, which cannot be accounted for by the air resistance itself. The acoustic streaming induced by ultrasound may bring an additional force against the motion of the drop due to the Bernoulli effect. This is responsible for the enhanced damping during the oscillation in acoustic levitation.

  9. Smoothed Particle Hydrodynamics pore-scale simulations of unstable immiscible flow in porous media

    SciTech Connect

    Bandara, Dunusinghe Mudiyanselage Uditha C.; Tartakovsky, Alexandre M.; Oostrom, Martinus; Palmer, Bruce J.; Grate, Jay W.; Zhang, Changyong

    2013-12-01

    We have conducted a series of high-resolution numerical experiments using the Pair-Wise Force Smoothed Particle Hydrodynamics (PF-SPH) multiphase flow model. First, we derived analytical expressions relating parameters in the PF-SPH model to the surface tension and static contact angle. Next, we used the model to study viscous fingering, capillary fingering, and stable displacement of immiscible fluids in porous media for a wide range of capillary numbers and viscosity ratios. We demonstrated that the steady state saturation profiles and the boundaries of viscous fingering, capillary fingering, and stable displacement regions compare favorably with micromodel laboratory experimental results. For displacing fluid with low viscosity, we observed that the displacement pattern changes from viscous fingering to stable displacement with increasing injection rate. When a high viscosity fluid is injected, transition behavior from capillary fingering to stable displacement occurred as the flow rate was increased. These observation also agree with the results of the micromodel laboratory experiments.

  10. Heat transfer between stratified immiscible liquid layers driven by gas bubbling across the interface

    SciTech Connect

    Greene, G.A.; Irvine, T.F. Jr.

    1988-01-01

    The modeling of molten core debris in the CORCON and VANESA computer codes as overlying, immiscible liquid layers is discussed as it relates to the transfer of heat and mass between the layers. This initial structure is identified and possible configurations are discussed. The stratified, gas-sparged configuration that is presently employed in CORCON and VANESA is examined and the existing literature for interlayer heat transfer is assessed. An experiment which was designed to measure interlayer heat transfer with gas sparging is described. The results are presented and compared to previously existing models. A dimensionless correlation for stratified, interlayer heat transfer with gas sparging is developed. This relationship is recommended for inclusion in CORCON-MOD2 for heat transfer between stratified, molten liquid layers. 12 refs., 6 figs., 3 tabs.

  11. Electrochemical alloying of immiscible Ag and Co for their structural and magnetic analyses

    NASA Astrophysics Data System (ADS)

    Santhi, Kalavathy; Kumarsan, Dhanapal; Vengidusamy, Naryanan; Arumainathan, Stephen

    2017-07-01

    Electrochemical alloying of immiscible Ag and Co was carried out at different current densities from electrolytes of two different concentrations, after optimizing the electrolytic bath and operating conditions. The samples obtained were characterized using X-ray diffraction to confirm the simultaneous deposition of Ag and Co and to determine their crystallographic structure. The atomic percentage of Ag and Co contents in the granular alloy was determined by ICP-OES analysis. The XPS spectra were observed to confirm the presence of Ag and Co in the metallic form in the granular alloy samples. The micrographs observed using scanning and transmission electron microscopes threw light on the surface morphology and the size of the particles. The magnetic nature of the samples was analyzed at room temperature by a vibration sample magnetometer. Their magnetic phase transition while heating was also studied to provide further evidence for the magnetic behaviour and the structure of the deposits.

  12. Characterizing the Use of Ultrasonic Energy in Promoting Uniform Composite Growth in Immiscible Alloys

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.; Fedoseyev, A. I.

    2000-01-01

    The results of experimental investigation and mathematical modeling for immiscible alloys subjected to ultrasonic influence are presented. It is known that in inoculated light alloy melts, ultrasonic treatment creates a new type of cast structure with extremely fine grains of uniform composition. This effect is produced across a wide range of freezing rates and technologies. However, it has not been demonstrated that the process can be successfully applied during controlled directional solidification processing. In this work we present the results from a set of directional solidification experiments and suggest describing the droplet size versus ultrasonic frequency and amplitude using an energy approach, followed with a more detailed analysis through numerical modeling of the ultrasonic field.

  13. Fluid-fluid interaction during miscible and immiscible displacement under ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Hamida, T.; Babadagli, T.

    2007-12-01

    This paper aims at identifying and analyzing the influence of high-frequency, high-intensity ultrasonic radiation at the interface between immiscible (different types of oils and aqueous solutions) and miscible (different types of oil and solvent) fluids. An extensive set of Hele-Shaw type experiments were performed for several viscosity ratios, and interfacial tension. Fractal analysis techniques were applied to quantify the degree of fingering and branching. This provided a rough assessment of the degree of perturbation generated at the interface when the capillary forces along with the viscous forces are effective. Miscible Hele-Shaw experiments were also presented to isolate the effect of viscous forces. We found that ultrasound acts to stabilize the interfacial front, and that such effect is most pronounced at low viscosity ratios.

  14. Capillary foams: highly stable bubbles formed by synergistic action of particles and immiscible liquid

    NASA Astrophysics Data System (ADS)

    Meredith, Carson; Zhang, Yi; Behrens, Sven

    2015-03-01

    Liquid foams are a familiar part of everyday life from beer and frothed milk to bubble baths; they also play important roles in enhanced oil recovery, lightweight packaging, and insulation. We report a new class of foams, obtained by frothing a suspension of colloidal particles in the presence of a small amount of an immiscible secondary liquid. A unique aspect of the new foams, termed capillary foams, is that suspended particles mediate spreading of a minority liquid around gas bubbles. The resulting mixed particle/liquid coating can stabilize bubbles against coalescence even when the particles alone cannot. We demonstrate the generality of capillary foams by forming them from a diverse set of particle/liquid combinations and rationalize the results with a simple free energy model. In addition to many applications as liquid foams, capillary foams can serve as precursors for hierarchically-structured solids with porosity on different length scales and with significant application potential.

  15. Miscible and immiscible, forced and unforced experiments on the Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Roberts, Michael; Mokler, Matthew; Jacobs, Jeffrey

    2012-11-01

    Experiments are presented in which an incompressible system of two liquids is accelerated to produce the Rayleigh-Taylor instability. In these experiments, the initially stable, stratified liquid combination is accelerated downward on a vertical rail system in one of two experimental apparatuses: an apparatus in which a system of weights and pulleys accelerates the liquid filled tank, or a new apparatus which uses linear induction motors to accelerate the tank to produce much greater acceleration levels. Both miscible and immiscible liquid combinations are used. In both apparatuses the resulting fluid flows are visualized with backlit imaging using LED backlights in conjunction with monochrome high-speed video cameras, both of which travel with the moving fluid filled containers. Initial perturbations are either unforced and allowed to progress from background noise or forced by vertically oscillating the liquid combination to produce parametric internal waves. The mixing layer growth rate α is determined for all cases and compared to numerical simulations and past experiments.

  16. Parametric resonance of capillary waves at the interface between two immiscible Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Kobyakov, D.; Bychkov, V.; Lundh, E.; Bezett, A.; Marklund, M.

    2012-08-01

    We study the parametric resonance of capillary waves on the interface between two immiscible Bose-Einstein condensates pushed towards each other by an oscillating force. Guided by analytical models, we solve numerically the coupled Gross-Pitaevskii equations for a two-component Bose-Einstein condensate at zero temperature. We show that, at moderate amplitudes of the driving force, the instability is stabilized due to nonlinear modifications of the oscillation frequency. When the amplitude of the driving force is large enough, we observe a detachment of droplets from the Bose-Einstein condensates, resulting in the generation of quantum vortices (skyrmions). We analytically investigate the vortex dynamics, and conditions of quantized vortex generation.

  17. Boiling of the interface between two immiscible liquids below the bulk boiling temperatures of both components.

    PubMed

    Pimenova, Anastasiya V; Goldobin, Denis S

    2014-11-01

    We consider the problem of boiling of the direct contact of two immiscible liquids. An intense vapour formation at such a direct contact is possible below the bulk boiling points of both components, meaning an effective decrease of the boiling temperature of the system. Although the phenomenon is known in science and widely employed in technology, the direct contact boiling process was thoroughly studied (both experimentally and theoretically) only for the case where one of liquids is becoming heated above its bulk boiling point. On the contrary, we address the case where both liquids remain below their bulk boiling points. In this paper we construct the theoretical description of the boiling process and discuss the actualisation of the case we consider for real systems.

  18. Dynamics of oil ganglia during immiscible displacement in water-wet porous media

    SciTech Connect

    Payatakes, A.C.

    1982-01-01

    Strong interest in the dynamic behavior of a population of non-wetting ganglia undergoing immiscible displacement has arisen because this problem is central to the understanding of oil-bank formation during enhanced oil recovery by chemical flooding. The same problem arises in the analysis of the relative permeabilities to any pair of wetting and non-wetting phases, when the saturation of the wetting phase exceeds approx. 0.60. Saturation of a phase is defined as the fraction of the void space that is occupied by that phase. Many drainage or imbibition phenomena fall into this category. This work concentrates on the case where the non-wetting phase is oleic (oil-based), the wetting phase is aqueous, and the objective is enhanced oil recovery. Discussions include theoretical modeling of the porous medium; mobilization, fissioning, and stranding of a solitary oil ganglion; and dynamics of oil-ganglion populations. 39 references.

  19. Effect of Particles on Rheology and Morphology of Immiscible PI/PDMS Polymer Blends

    NASA Astrophysics Data System (ADS)

    Thareja, Prachi; Velankar, Sachin S.

    2008-07-01

    We present the effects of several interfacially-active particles on the rheology of model immiscible polymer blends of polyisoprene (PI) and polydimethylsiloxane (PDMS) with a droplet-matrix morphology. The particles are capable of adsorbing at the PI/PDMS interface, and hence addition of these particles is expected to significantly affect the breakup and coalescence of drops and consequently the drop size. Using rheology (specifically, strain recovery upon cessation of shear) as a tool to probe morphological evolution, we show that none of the particles are able to prevent coalescence of the drops, at least at a particle loading of 0.5 vol.%. Remarkably however, some particle types strongly promote coalescence in some blends.

  20. Effect of pressure on cation partitioning between immiscible liquids in the system Ti0 2-SiO 2

    NASA Astrophysics Data System (ADS)

    Circone, S.; Agee, C. B.

    1995-03-01

    Liquidus phase relations in the system Si0 2-TiO 2 have been determined at 3.0 GPa to investigate the effect of pressure on the partitioning of Si and Ti between coexisting immiscible liquids. Experiments on oxide mixtures containing 10, 50, 90, and 100 mol% TiO 2 were performed in multi-anvil and piston-cylinder apparatus at 2173-2740 K. At 1 atm, immiscible liquids form because the liquid structures are dissimilar: tetravalent cations occur in primarily fourfold (Si0 2-rich liquid) vs. sixfold (TiO 2-rich liquid) coordination by oxygen. At 3.0 GPa, immiscible liquids also coexist, but the phase relations and liquid compositions are significantly different. The eutectic liquid is now Ti0 2-rich (78.4 vs. 8.1 mol% TiO 2 at 1 atm). Above the liquidus, the coexisting immiscible liquids are enriched in Si0 2. The Si0 2 content of the TiO 2-rich liquid has increased by more than a factor of 3, while the TiO2-content of the SiO 2-rich liquid has decreased by 1/2. The persistence of a wide solvus implies that pressure does not cause liquid structure assimilation. The observed shift in immiscible liquid compositions indicated that pressure has raised the activity of TiO 2 in the liquid dominated by tetravalent cations in fourfold coordination and lowered the activity of SiO 2 in a liquid dominated by tetravalent cations in sixfold coordination. The decrease in TiO 2 content of the SiO 2-rich liquid with pressure is probably related to the positive volume of mixing observed in 1 atm glasses in this composition range. The enhanced solubility of SiO 2 in the TiO 2-rich liquid with pressure may be due to a pressure-induced increase in the coordination state of Si.

  1. Immiscible Hydrocarbon and Aqueous Fluids Under Subduction Zone Conditions and Implications for the Deep Carbon Cycle

    NASA Astrophysics Data System (ADS)

    Huang, F.; Daniel, I.; Cardon, H.; Montagnac, G.; Sverjensky, D. A.

    2015-12-01

    Subducting slabs recycle rocks into the deep Earth releasing fluids which may cause partial melting and possible oxidation of the mantle wedge. Recent theoretical studies1 indicate that at pressures greater than about 3.0 GPa these fluids could contain high concentrations of organic and inorganic C-species with a wide range of C-oxidation states at equilibrium. If so, such fluids could play an important role in the deep carbon cycle, including the formation of diamond. However, direct experimental observations of the speciation in the fluids are needed. We studied 1.0 M aqueous Na-formate and 1.0 M Na-acetate solutions in the diamond anvil cell using Raman spectroscopy at 300 ºC and 3.0 GPa for up to 60 hours. Our preliminary results indicate that formate rapidly decomposed to bicarbonate/carbonate species and methane, with no detectable H2. Acetate decomposed much more slowly. Within the first two hours of heating, crystals of Na2CO3 precipitated in the fluid, and kept growing while immiscible droplets of hydrocarbon appeared and persisted throughout the experiments at elevated temperature and pressure. In the aqueous fluid, acetate and HCO3- were present during the first 6 hours, and then CO32- and acetate after 20 hours of heating. The final HCO3- /CO32- ratio was constant indicating a constant pH. This is the first in situ observation of persistent immiscible fluid hydrocarbons formed from an aqueous precursor at upper mantle pressures. Our results suggest that Earth's subduction zone fluids at high pressures might involve fluid hydrocarbon species as well as inorganic and organic aqueous C-species, which considerably broadens the picture of deep carbon sources, cycles and sinks. [1] Sverjensky et at. (2014), Nat. Geosci. 7, 909-913.

  2. Magmatic immiscibility and fluid phase evolution in the Mount Genis granite (southeastern Sardinia, Italy)

    NASA Astrophysics Data System (ADS)

    Frezzotti, Maria Luce

    1992-01-01

    The Mount Genis granite is one of the post-tectonic intrusives emplaced late in the magmatic history of the Hercynian batholith in Sardinia. Devitrified silicate melt inclusions are present in some (magmatic) rock-forming and miarolitic quartz. These magmatic remnants show initial melting at 680- 720°C. High-temperature observations (700-800°C) revealed the presence in some of the inclusions of mixed hydrosaline melt (L1) and silicate melt (L2), with extremely variable L1/L2 ratios. Electron microprobe analyses indicate L1 to be K-Na dominated chlorides. Inclusions of mixed silicate and hydrosaline melts are interpreted to have been formed by heterogeneous trapping of two immiscible fluid phases (silicate-hydrosaline) after second boiling, most likely during the final crystallization stage. Magma-derived brines (63 eq wt% NaCl) circulated at subsolidus conditions from ≈600°C and were retained in the miarolitic cavities down to about 400°C. Fluid unmixing occurred locally in the miarolitic cavities from 550° to 412°C. At temperatures of ≈400° to 100°C the microgranite was invaded by diluted waters (≈4-5 eq wt% NaCl). A possible model for fluid evolution begins with a hydrosaline melt exsolving from the magma at the late-magmatic stage. The absence of boiling within the volatile (hydrosaline) system shows that brines can occur by direct magmatic immiscibility. The comprehensive hydrothermal evolution suggests a nearly isobaric cooling path, with local boiling episodes in the miaroles, probably in coincidence with invasion of external waters.

  3. Experiments on front roughness and averaged saturation for immiscible displacement in heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Heiss, V.; Neuweiler, I.; Faerber, A.

    2009-04-01

    For mass transfer during two-phase two-component flow processes in heterogeneous porous media, the fluid-fluid interface of the two-phases have a strong influence. To predict mass transfer it is therefore important to determine the interface properties. An important characterization criterion for displacement of one fluid by another, immiscible one in porous media, is the morphology of the fluid-fluid interface. The interface morphology is investigated intensely since a long time. It is determined by the interplay between capillary, gravity and viscous forces and by the structure of the pore space. The interface morphology influences the modeling of a displacement process on the Darcy scale, where the pore scale is no longer resolved. However, the interface criteria on the pore scale cannot necessarily be transferred to the larger scale. This is in particular true in heterogeneous media, where the structure of material interfaces on the large scale may determine the flow process. Immiscible displacement fronts on a Darcy scale are often sharp and may show instabilities on the larger scale. Pore scale instabilities, on the other hand, may appear as stabilized on the large scale due to large scale structures. We will present observations of displacement fronts in Darcy scale heterogeneous media, where fluid content was measured using optical methods. The front properties were analyzed for different flow regimes and structures. The growth rate of the front roughness shows a different behavior than the spatially averaged fluid content. While the front is in most cases stable after some time, the width of the distribution of the averaged fluid content continues to grow due to pore-scale and macroscopic trapping events.

  4. Optofluidic restricted imaging, spectroscopy and counting of nanoparticles by evanescent wave using immiscible liquids.

    PubMed

    Liang, L; Zuo, Y F; Wu, W; Zhu, X Q; Yang, Y

    2016-08-21

    Conventional flow cytometry (FC) suffers from the diffraction limit for the detection of nanoparticles smaller than 100 nm, whereas traditional total internal reflection (TIR) microscopy can only detect few samples near the solid-liquid interface mostly in static states. Here we demonstrate a novel on-chip optofluidic technique using evanescent wave sensing for single nanoparticle real time detection by combining hydrodynamic focusing and TIR using immiscible flows. The immiscibility of the high-index sheath flow and the low-index core flow naturally generate a smooth, flat and step-index interface that is ideal for the TIR effect, whose evanescent field can penetrate the full width of the core flow. Hydrodynamic focusing can focus on all the nanoparticles in the extreme centre of the core flow with a width smaller than 1 μm. This technique enables us to illuminate every single sample in the running core flow by the evanescent field, leaving none unaffected. Moreover, it works well for samples much smaller than the diffraction limit. We have successfully demonstrated the scattering imaging and counting of 50 nm and 100 nm Au nanoparticles and also the fluorescence imaging and counting of 200 nm beads. The effective counting speeds are estimated as 1500, 2300 and 2000 particles per second for the three types of nanoparticles, respectively. The optical scattering spectra were also measured to determine the size of individual Au nanoparticles. This provides a new technique to detect nanoparticles and we foresee its application in the detection of molecules for biomedical analyses.

  5. Nanoscale Phase Immiscibility in High-ZT Bulk Lead Telluride Thermoelectric Materials

    NASA Astrophysics Data System (ADS)

    Girard, Steven Neal

    Renewable energy initiatives have increased interest in thermoelectric materials as an option for inexpensive and environmentally friendly waste heat-to-power generation. Unfortunately, low efficiencies have limited their wide-scale utilization. This work describes the synthesis and characterization of bulk nanostructured thermoelectric materials wherein natural phase immiscibility is manipulated to selectively generate nanoscale inclusions of a second phase that improve their efficiency through reductions in lattice thermal conductivity. The PbTe-PbS system exhibits natural phase separation by nucleation and growth or spinodal decomposition phase transformations depending on composition and temperature treatment. Through rapid quenching, nearly ideal solid solution alloys of PbTe-PbS are observed by powder X-ray diffraction. However, characterization by solid-state NMR and IR reflectivity show that solid solutions are obtained for rapidly quenched samples within the nucleation and growth region of the phase diagram, but samples within the spinodal decomposition region exhibit very slight phase immiscibility. We report the temperatures of phase separation using high temperature powder X-ray diffraction. Microscopy reveals that phase separation in PbTe-PbS naturally produces nanoinclusions. A decrease in lattice thermal conductivity is observed as a result of the solid solution-to-nanostructured phase transformation in this materials system, increasing thermoelectric figure of merit. Sn addition to PbTe-PbS produces a pseudobinary system of PbTe-PbSnS 2. This materials system produces microscale lamellae that effectively reduce lattice thermal conductivity. Unfortunately, the PbSnS2 inclusions also scatter electrons, reducing electrical conductivity and producing only a minimal increase in thermoelectric figure of merit. We additionally investigate PbSnS2 as prepared through Bridgman crystal growth. PbTe-PbS doped with Na appears to increase the kinetic rate of

  6. Quasi-Immiscible Spreading of Aqueous Surfactant Solutions on Entangled Aqueous Polymer Solution Subphases

    PubMed Central

    Sharma, Ramankur; Corcoran, Timothy E.; Garoff, Stephen; Przybycien, Todd M.; Swanson, Ellen R.; Tilton, Robert D.

    2014-01-01

    Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface active dye, was added to the surfactant solution. The spreading progresses through a series of events. Marangoni stresses initiate the convective spreading of the drop. Simultaneously, surfactant escapes across the drop’s contact line within a second of deposition and causes a change in subphase surface tension outside the drop on the order of 1 mN/m. Convective spreading of the drop ends within 2–3 seconds of drop deposition, when a new interfacial tension balance is achieved. Surfactant escape depletes the drop of surfactant and the residual drop takes the form of a static lens of non-zero contact angle. On longer time scales, the surfactant dissolves into the subphase. The lens formed by the water in the deposited drop persists for as long as 3 minutes after the convective spreading process ends due to the long diffusional timescales associated with the underlying entangled polymer solution. The persistence of the lens suggests that the drop phase behaves as if it were immiscible with the subphase during this time period. Whereas surfactant escapes the spreading drop and advances on the subphase/vapor interface, hydrophilic dye molecules in the drop do not escape, but remain with the drop throughout the convective spreading. The quasi-immiscible nature of the spreading event suggests that the chemical properties of the surfactant and subphase are much less important than their physical properties, consistent with prior qualitative studies of spreading of different types of surfactants on entangled polymer subphases: the

  7. Quasi-immiscible spreading of aqueous surfactant solutions on entangled aqueous polymer solution subphases.

    PubMed

    Sharma, Ramankur; Corcoran, Timothy E; Garoff, Stephen; Przybycien, Todd M; Swanson, Ellen R; Tilton, Robert D

    2013-06-26

    Motivated by the possibility of enhancing aerosol drug delivery to mucus-obstructed lungs, the spreading of a drop of aqueous surfactant solution on a physically entangled aqueous poly(acrylamide) solution subphase that mimics lung airway surface liquid was investigated. Sodium dodecyl sulfate was used as the surfactant. To visualize spreading of the drop and mimic the inclusion of a drug substance, fluorescein, a hydrophilic and non-surface-active dye, was added to the surfactant solution. The spreading progresses through a series of events. Marangoni stresses initiate the convective spreading of the drop. Simultaneously, surfactant escapes across the drop's contact line within a second of deposition and causes a change in subphase surface tension outside the drop on the order of 1 mN/m. Convective spreading of the drop ends within 2-3 s of drop deposition, when a new interfacial tension balance is achieved. Surfactant escape depletes the drop of surfactant, and the residual drop takes the form of a static lens of nonzero contact angle. On longer time scales, the surfactant dissolves into the subphase. The lens formed by the water in the deposited drop persists for as long as 3 min after the convective spreading process ends due to the long diffusional time scales associated with the underlying entangled polymer solution. The persistence of the lens suggests that the drop phase behaves as if it were immiscible with the subphase during this time period. Whereas surfactant escapes the spreading drop and advances on the subphase/vapor interface, hydrophilic dye molecules in the drop do not escape but remain with the drop throughout the convective spreading. The quasi-immiscible nature of the spreading event suggests that the chemical properties of the surfactant and subphase are much less important than their physical properties, consistent with prior qualitative studies of spreading of different types of surfactants on entangled polymer subphases: the selection of

  8. Solid-State NMR Study of Metastable Immiscibility in Alkali Borosilicate Glasses

    NASA Astrophysics Data System (ADS)

    Du, L.; Stebbins, J. F.

    2001-12-01

    Liquid-liquid phase separation is a critical issue in controlling and designing the physical properties of borosilicate glasses such as chemical durability, crystal nucleation, and high temperature strength and can provide insight into unmixing in natural magmatic systems as well. It is important to clarify this phenomenon, especially the immiscibility boundaries, which can be difficult to determine by conventional methods. High resolution NMR can provide a sensitive probe for the observation of phase separation in glass systems. In the M2O-B2O3-SiO2 system (M= Li, Na, K), we have used oxygen-17 MQMAS (Multiple Quantum Magic Angle Spinning) technique to explore changes in connectivities between SiO4, BO3 and BO4 units, based on changes in populations of bridging oxygens, such as B-O-B, B-O-Si and Si-O-Si, and of non-bridging oxygens. We have also used boron-11 MAS and MQMAS to quantify populations of borate units with varying first shell coordination and connectivity to other network units, e.g., "ring" vs. "non-ring" BO3 groups. In a series of alkali borosilicates of the same stoichiometry, the population of Si-O-B oxygen for the Li glass is significantly lower than that for Na and K borosilicates. This implies that the Li glass has a greater degree of phase separation at a submicroscopic scale as expected from phase diagrams. O-17 MQMAS NMR is also useful in determining the effect of quenching rate and annealing temperature on the degree of phase separation. In the Na borosilicates, a reduced concentration of Si-O-B in compositions within the immiscibility region suggests that even optically homogeneous glasses have small-scale heterogeneity. In the B-11 MAS and MQMAS studies, the ratio of BO3 to BO4 does not change with annealing. The non-ring BO3, however, converts to ring BO3 with annealing, which increases the degree of phase separation. In the study of Na2O-B2O3-SiO2 glasses with different Na contents, Si-O-B(III) and Si-O-B(IV) as well as B-O-B(III) and B

  9. A Study of Undercooling Behavior Of Immiscible Metal Alloys in the Absence of Crucible-Induced Nucleation

    NASA Technical Reports Server (NTRS)

    Robinson, Michael B.; Rathz, Thomas J.; Li, Delin; Workman, Gary

    1998-01-01

    The purpose of this study is to investigate the question: Would eliminating the crucible eliminate the wall-induced nucleation of one of the liquid phases in an immiscible alloy and result in undercooling of the liquid into the metastable region thereby producing significant differences in the separation process and the microstructure upon solidification. Another primary objective of this research is to study systems with a metastable miscibility gap and to directly determine the metastable liquid miscibility gap by undercooling experiments. Nucleation and growth of droplets in these undercooled metallic liquid-liquid mixtures is also being studied. Results of this investigation indicate that containerless processing of immiscibles may not promote the undercooling of the single-phase liquid into the metastable region. Although no recalescence event was observed for this liquid-liquid transition, undercooling did occur across the miscibility gap for the solidification of the Ti phase that eventually separated.

  10. APPLICATION OF A LUMPED-PROCESS MATHEMATICAL MODEL TO DISSOLUTION OF NON-UNIFORMLY DISTRIBUTED IMMISCIBLE LIQUID IN HETEROGENEOUS POROUS MEDIA

    PubMed Central

    Marble, J. C.; DiFilippo, E. L.; Zhang, Z.; Tick, G. R.; Brusseau, M. L.

    2010-01-01

    The use of a lumped-process mathematical model to simulate the complete dissolution of immiscible liquid non-uniformly distributed in physically heterogeneous porous-media systems was investigated. The study focused specifically on systems wherein immiscible liquid was poorly accessible to flowing water. Two representative, idealized scenarios were examined, one wherein immiscible liquid at residual saturation exists within a lower-permeability unit residing in a higher-permeability matrix, and one wherein immiscible liquid at higher saturation (a pool) exists within a higher-permeability unit adjacent to a lower-permeability unit. As expected, effluent concentrations were significantly less than aqueous solubility due to dilution and by-pass flow effects. The measured data were simulated with two mathematical models, one based on a simple description of the system and one based on a more complex description. The permeability field and the distribution of the immiscible-liquid zones were represented explicitly in the more complex, distributed-process model. The dissolution rate coefficient in this case represents only the impact of local-scale (and smaller) processes on dissolution, and the parameter values were accordingly obtained from the results of experiments conducted with one-dimensional, homogeneously-packed columns. In contrast, the system was conceptualized as a pseudo-homogeneous medium with immiscible liquid uniformly distributed throughout the system for the simpler, lumped-process model. With this approach, all factors that influence immiscible-liquid dissolution are incorporated into the calibrated dissolution rate coefficient, which in such cases serves as a composite or lumped term. The calibrated dissolution rate coefficients obtained from the simulations conducted with the lumped-process model were approximately two to three orders of magnitude smaller than the independently-determined values used for the simulations conducted with the

  11. Immiscible phase nucleic acid purification eliminates PCR inhibitors with a single pass of paramagnetic particles through a hydrophobic liquid.

    PubMed

    Sur, Kunal; McFall, Sally M; Yeh, Emilie T; Jangam, Sujit R; Hayden, Mark A; Stroupe, Stephen D; Kelso, David M

    2010-09-01

    Extraction and purification of nucleic acids from complex biological samples for PCR are critical steps because inhibitors must be removed that can affect reaction efficiency and the accuracy of results. This preanalytical processing generally involves capturing nucleic acids on microparticles that are then washed with a series of buffers to desorb and dilute out interfering substances. We have developed a novel purification method that replaces multiple wash steps with a single pass of paramagnetic particles (PMPs) though an immiscible hydrophobic liquid. Only two aqueous solutions are required: a lysis buffer, in which nucleic acids are captured on PMPs, and an elution buffer, in which they are released for amplification. The PMPs containing the nucleic acids are magnetically transported through a channel containing liquid wax that connects the lysis chamber to the elution chamber in a specially designed cartridge. Transporting PMPs through the immiscible phase yielded DNA and RNA as pure as that obtained after extensive wash steps required by comparable purification methods. Our immiscible-phase process has been applied to targets in whole blood, plasma, and urine and will enable the development of faster and simpler purification systems.

  12. The Role of Air-Electrode Structure on the Incorporation of Immiscible PFCs in Nonaqueous Li-O2 Battery.

    PubMed

    Balaish, Moran; Ein-Eli, Yair

    2017-03-22

    Perfluorocarbons (PFCs) are considered advantageous additives to nonaqueous Li-O2 battery due to their superior oxygen solubility and diffusivity compared to common battery electrolytes. Up to now, the main focus was concentrated on PFCs-electrolyte investigation; however, no special attention was granted to the role of carbon structure in the PFCs-Li-O2 system. In our current research, immiscible PFCs, rather than miscible fluorinated ethers, were added to activated carbon class air electrode due to their higher susceptibility toward O2(•-) attack and to their ability to shift the reaction from two-phase to an artificial three-phase reaction zone. The results showed superior battery performance upon PFCs addition at lower current density (0.05 mA cm(-2)) but unexpectedly failed to do so at higher current density (0.1 and 0.2 mA cm(-2)), where oxygen transport limitation is best illustrated. The last was a direct result of liquid-liquid displacement phenomenon occurring when the two immiscible liquids were introduced into the porous carbon medium. The investigation and role of carbon structure on the mechanism upon PFCs addition to Li-O2 system are suggested based on electrochemical characterization, wettability behavior studies, and the physical adsorption technique. Finally, we suggest an optimum air-electrode structure enabling the incorporation of immiscible PFCs in a nonaqueous Li-O2 battery.

  13. Facile and rapid DNA extraction and purification from food matrices using IFAST (immiscible filtration assisted by surface tension).

    PubMed

    Strotman, Lindsay N; Lin, Guangyun; Berry, Scott M; Johnson, Eric A; Beebe, David J

    2012-09-07

    Extraction and purification of DNA is a prerequisite to detection and analytical techniques. While DNA sample preparation methods have improved over the last few decades, current methods are still time consuming and labor intensive. Here we demonstrate a technology termed IFAST (Immiscible Filtration Assisted by Surface Tension), that relies on immiscible phase filtration to reduce the time and effort required to purify DNA. IFAST replaces the multiple wash and centrifugation steps required by traditional DNA sample preparation methods with a single step. To operate, DNA from lysed cells is bound to paramagnetic particles (PMPs) and drawn through an immiscible fluid phase barrier (i.e. oil) by an external handheld magnet. Purified DNA is then eluted from the PMPs. Here, detection of Clostridium botulinum type A (BoNT/A) in food matrices (milk, orange juice), a bioterrorism concern, was used as a model system to establish IFAST's utility in detection assays. Data validated that the DNA purified by IFAST was functional as a qPCR template to amplify the bont/A gene. The sensitivity limit of IFAST was comparable to the commercially available Invitrogen ChargeSwitch® method. Notably, pathogen detection via IFAST required only 8.5 μL of sample and was accomplished in five-fold less time. The simplicity, rapidity and portability of IFAST offer significant advantages when compared to existing DNA sample preparation methods.

  14. Control of Selective Ion Transfer across Liquid–Liquid Interfaces: A Rectifying Heterojunction Based on Immiscible Electrolytes

    PubMed Central

    2016-01-01

    The current rectification displayed by solid-state p–n semiconductor diodes relies on the abundance of electrons and holes near the interface between the p–n junction. In analogy to this electronic device, we propose here the construction of a purely ionic liquid-state electric rectifying heterojunction displaying an excess of monovalent cations and anions near the interface between two immiscible solvents with different dielectric properties. This system does not need any physical membrane or material barrier to show preferential ion transfer but relies on the ionic solvation energy between the two immiscible solvents. We construct a simple device, based on an oil/water interface, displaying an asymmetric behavior of the electric current as a function of the polarity of an applied electric field. This device also exhibits a region of negative differential conductivity, analogous to that observed in brain and heart cells via voltage clamp techniques. Computer simulations and mean field theory calculations for a model of this system show that the application of an external electric field is able to control the bulk concentrations of the ionic species in the immiscible liquids in a manner that is asymmetric with respect to the polarity or direction of the applied electric field. These properties make possible to enhance or suppress selective ion transport at liquid−liquid interfaces with the application of an external electric field or electrostatic potential, mimicking the function of biological ion channels, thus creating opportunities for varied applications. PMID:27924315

  15. HIV Viral RNA Extraction in Wax Immiscible Filtration Assisted by Surface Tension (IFAST) Devices

    PubMed Central

    Berry, Scott M.; LaVanway, Alex J.; Pezzi, Hannah M.; Guckenberger, David J.; Anderson, Meghan A.; Loeb, Jennifer M.; Beebe, David J.

    2015-01-01

    The monitoring of viral load is critical for proper management of antiretroviral therapy for HIV-positive patients. Unfortunately, in the developing world, significant economic and geographical barriers exist, limiting access to this test. The complexity of current viral load assays makes them expensive and their access limited to advanced facilities. We attempted to address these limitations by replacing conventional RNA extraction, one of the essential processes in viral load quantitation, with a simplified technique known as immiscible filtration assisted by surface tension (IFAST). Furthermore, these devices were produced via the embossing of wax, enabling local populations to produce and dispose of their own devices with minimal training or infrastructure, potentially reducing the total assay cost. In addition, IFAST can be used to reduce cold chain dependence during transportation. Viral RNA extracted from raw samples stored at 37°C for 1 week exhibited nearly complete degradation. However, IFAST-purified RNA could be stored at 37°C for 1 week without significant loss. These data suggest that RNA isolated at the point of care (eg, in a rural clinic) via IFAST could be shipped to a central laboratory for quantitative RT-PCR without a cold chain. Using this technology, we have demonstrated accurate and repeatable measurements of viral load on samples with as low as 50 copies per milliliter of sample. PMID:24613822

  16. Flow of immiscible ferrofluids in a planar gap in a rotating magnetic field

    NASA Astrophysics Data System (ADS)

    Sule, Bhumika; Torres-Díaz, Isaac; Rinaldi, Carlos

    2015-07-01

    Analytical solutions are obtained for the steady, fully developed flow of two layers of immiscible ferrofluids of different thicknesses between two parallel plates. Interfacial linear and internal angular momentum balance relations are derived for the case when there is a ferrofluid-ferrofluid interface to obtain the translational and spin velocity profiles in the gap. As expected for the limit of low applied field amplitude, the magnitude of the translational velocity is directly proportional to the frequency of the applied magnetic field and to the square of the magnetic field amplitude. Expressions for the velocity profiles are obtained for the zero spin viscosity and non-zero spin viscosity cases and the effect of applied pressure gradient on the flows is studied. The spin velocity in both ferrofluid phases is in the direction of the rotating magnetic field, except for cases of extreme applied pressure gradients for which the fluid vorticity opposes the spin. We find that for the case of non-zero spin viscosity, flow reversals are predicted using representative ferrofluid property values and field conditions. The unique predictions of the solution with non-zero spin viscosity could be used to experimentally test the existence of couple stresses in ferrofluids and the validity of previously reported values of the so-called spin viscosity.

  17. An overview of instability and fingering during immiscible fluid flow in porous and fractured media

    SciTech Connect

    Chen, G.; Neuman, S.P.; Taniguchi, M.

    1995-04-01

    Wetting front instability is an important phenomenon affecting fluid flow and contaminant transport in unsaturated soils and rocks. It causes the development of fingers which travel faster than would a uniform front and thus bypass much of the medium. Water saturation and solute concentration in such fingers tend to be higher than in the surrounding medium. During infiltration, fingering may cause unexpectedly rapid arrival of water and solute at the water-table. This notwithstanding, most models of subsurface flow and transport ignore instability and fingering. In this report, we survey the literature to assess the extent to which this may or may not be justified. Our overview covers experiments, theoretical studies, and computer simulations of instability and fingering during immiscible two-phase flow and transport, with emphasis on infiltration into soils and fractured rocks. Our description of instability in an ideal fracture (Hele-Shaw cell) includes an extension of existing theory to fractures and interfaces having arbitrary orientations in space. Our discussion of instability in porous media includes a slight but important correction of existing theory for the case of an inclined interface. We conclude by outlining some potential directions for future research. Among these, we single out the effect of soil and rock heterogeneities on instability and preferential flow as meriting special attention in the context of nuclear waste storage in unsaturated media.

  18. The Prospects of Nanorods as Blending Agents in Immiscible Binary Polymer Blends

    NASA Astrophysics Data System (ADS)

    Hore, Michael J. A.; Laradji, Mohamed

    2006-03-01

    Systematic, large scale dissipative particle dynamics computer simulations performed in three dimensions indicate that the dynamics of phase separation of polymer blends containing rigid nanorods can be substantially slower than that of a pure binary blend, and that the dynamics depend greatly on the aspect ratio, i.e length/diameter, of the nanoparticles. When compared with spherical nanoparticles, it is also found that nanorods with the same volume fraction, or same surface area, are more effective in slowing down the dynamics of the blend -- an indication that the anisotropy of the nanoparticles plays an important role in the phase separation kinetics. For a given volume fraction of rods, the domain growth exponent decreases (and growth may become non-algebraic) as the aspect ratio of the rods is increased. Growth is also slowed as the volume fraction of the nanorods is increased for a given aspect ratio. Additionally, it is found that the effect of lengthwise polydisperse rods is similar to that of monodisperse rods with a length equal to the mean length of the polydisperse rods. In cases with high aspect ratio rods or high volume fractions of rods, systems often proceed to micro-phase separated states -- results not seen for nanospheres. The upshot of these results is that nanorods may potentially be used as effective emulsifiers of immiscible binary polymer blends. The thermodynamic stability of these micro-phase separated states will be discussed.

  19. Linear stability analysis of immiscible two-phase flow in porous media

    NASA Astrophysics Data System (ADS)

    Riaz, Amir

    2005-11-01

    Linear stability analysis of immiscible displacements is carried out for both viscously and gravitationally unstable two-phase flows in porous media with very large adverse viscosity ratios. Capillary dispersion is the proper dissipative mechanism in this case which sets both the preferred length scale and the band width of the spectrum of unstable length scales. The growth rate, the most dangerous and the cutoff wavenumbers, all scale linearly with the capillary number. We show that the instability is governed by fluid properties across the shock rather than those across the full Buckley--Leverett profile. The shock total mobility ratio provides a sufficient condition for the onset of instability; however, it is not an appropriate criterion for predicting the magnitude of the growth rate, particularly for large viscosity ratios. The details of the relative permeability functions are observed to have a significant influence on the stability characteristics. For neutrally buoyant flows the maximum growth rate scales linearly with the viscosity ratio while the most dangerous and the cutoff wavenumbers scale with the square root of the viscosity ratio.

  20. Influence of chemical reaction decreasing interfacial tension on immiscible viscous fingering

    NASA Astrophysics Data System (ADS)

    Tsuzuki, Reiko; Fujimura, Masanari; Yuichiro, Nagatsu

    2016-11-01

    We have experimentally investigated the effects of chemical reaction on immiscible viscous fingering (VF). In the present study, we use a chemical reaction producing a surfactant leading to a decrease in interfacial tension. In our experiment, a more viscous paraffin oil containing linoleic acid is displaced by a less viscous NaOHaq in a radial Hele-Shaw cell. We have found the influence of the reaction on the VF pattern depends on the displacement flow rate. At low flow rate, the reaction makes the fingers narrower. On the other hand, at intermediate flow rate, the reaction makes the fingers wider. At high flow rate, there is little influence of the reaction. These results can be interpreted as follows; when the reaction rate is much faster than the flow rate, interfacial tension is decreased uniformly over the interface. As a result, more finger-splitting occur and the fingers become narrower. When the reaction rate and flow rate are competing, the interfacial tension gradient is formed along the interface. As a result, Marangoni convection is produced, which leads to wider fingers. When the flow rate is much faster than the reaction rate, little reaction occurs during the formation of VF. As a result, the reaction does not influence on VF pattern.

  1. Low energy metastable states and immiscibility in (SiC)1-X-(AlN)X

    NASA Astrophysics Data System (ADS)

    Burton, Benjamin; van de Walle, Axel; Davydov, Albert; Vinograd, Victor

    2009-03-01

    A cluster expansion Hamiltonian was fit to VASP/PAW calculated supercell formation energies, δEf, and first principles based phase diagrams (miscibility gaps) were calculated for the wurtzite-structure pseudobinary system SiC1-XAlNX. An unusually wide range of 3 δEf 125 kJ/mole MX (M= Al, Si; X= N, C) was calculated and all supercells with δEf 8 kJ/mole exhibited characteristic (SiC)m(AlN)n crystallography, in which (SiC)m indicates m SiC-double layers to the hexagonal c-axis, and similarly for (AlN)n. The prediction of (SiC)m(AlN)n low-energy metastable states, may explain why one can synthesize SiC1-XAlNX films, or single crystals of arbitrary bulk composition, in spite of the very strong tendency toward immiscibility. Specifically, one expects that metastable films or single crystals will be dominated by a disordered stacking of SiC- and AlN-double layers.

  2. A Membrane-Free Redox Flow Battery with Two Immiscible Redox Electrolytes.

    PubMed

    Navalpotro, Paula; Palma, Jesus; Anderson, Marc; Marcilla, Rebeca

    2017-10-02

    Flexible and scalable energy storage solutions are necessary for mitigating fluctuations of renewable energy sources. The main advantage of redox flow batteries is their ability to decouple power and energy. However, they present some limitations including poor performance, short-lifetimes, and expensive ion-selective membranes as well as high price, toxicity, and scarcity of vanadium compounds. We report a membrane-free battery that relies on the immiscibility of redox electrolytes and where vanadium is replaced by organic molecules. We show that the biphasic system formed by one acidic solution and one ionic liquid, both containing quinoyl species, behaves as a reversible battery without any membrane. This proof-of-concept of a membrane-free battery has an open circuit voltage of 1.4 V with a high theoretical energy density of 22.5 Wh L(-1) , and is able to deliver 90 % of its theoretical capacity while showing excellent long-term performance (coulombic efficiency of 100 % and energy efficiency of 70 %). © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  3. Drop fragmentation at impact onto a bath of an immiscible liquid.

    PubMed

    Lhuissier, H; Sun, C; Prosperetti, A; Lohse, D

    2013-06-28

    The impact of a drop onto a deep bath of an immiscible liquid is studied with emphasis on the drop fragmentation into a collection of noncoalescing daughter drops. At impact the drop flattens and spreads at the surface of the crater it transiently opens in the bath and reaches a maximum deformation, which gets larger with increasing impact velocity, before surface tension drives its recession. This recession can promote the fragmentation by two different mechanisms: At moderate impact velocity, the drop recession converges to the axis of symmetry to form a jet which then fragments by a Plateau-Rayleigh mechanism. At higher velocity the edge of the receding drop destabilizes and shapes into radial ligaments which subsequently fragment. For this latter mechanism the number N∝We3 and the size distribution of the daughter drops p(d)∝d-4 as a function of the impact Weber number We are explained on the basis of the observed spreading of the drop. The universality of this model for the fragmentation of receding liquid sheets might be relevant for other configurations.

  4. Wetting of a liquid surface by another immiscible liquid in microgravity

    NASA Astrophysics Data System (ADS)

    Abel, Gilles; Ross, Guy G.; Andrzejewski, Lukasz

    2004-01-01

    The investigation of interfacial properties is essential to the development of new drugs either on earth or, particularly, in the absence of gravity. Under the reduced gravity conditions of parabolic flights, we have shown that, using an appropriate cell setup in order to control liquid surfaces, a liquid drop can be expanded onto and withdrawn from another immiscible liquid, which permits the measurement of the contact angle of this system. Surface energies of liquids being easily measurable, this technique allows a verification of numerous models used in interface science. During each parabola, 20 s of microgravity measurements permitted the acquisition of video pictures of these drops. Contact angles have been obtained from goniometric analysis of the recorded images. Generally, the drops obtained satisfied the equilibrium state predicted by Neumann's equations. However, unexpected long lasting metastable drops have also been observed on a curved unconfined liquid surface. The existence of a drop-sinking barrier, larger for a curved liquid surface, is proposed to explain this observation.

  5. Flow characteristics of two immiscible liquid layers subjected to a horizontal temperature gradient.

    PubMed

    Someya, Satoshi; Munakata, Tetsuo; Nishio, Masahiro; Okamoto, Koji; Madarame, Haruki

    2002-10-01

    Marangoni convection, driven by an interfacial instability due to a surface tension gradient, presents a significant problem in crystal growth in normal microgravity environments. It is important to suppress and control the convection phenomenon for better material processing, especially in crystal growth by the liquid encapsulated Czochralski or liquid encapsulated floating zone techniques, in which the melt is encapsulated in an immiscible medium. Marangoni convection can occur on the liquid-liquid interface and on the gas-liquid free surface. Buoyancy driven convection can also affect and complicate the flow. In the study we report here, experiments were carried out with two liquid layers, silicone oil and fluorinert, in an open and enclosed rectangular cavity. The flow in the cavity was subjected to a horizontal temperature gradient. The interactive flow near the liquid-liquid interface was measured by the particle image velocimetry technique. The measured flow field is in agreement with numerical predictions. Free surface fluctuations with several dominant frequencies were also measured.

  6. Drop Fragmentation at Impact onto a Bath of an Immiscible Liquid

    NASA Astrophysics Data System (ADS)

    Lhuissier, H.; Sun, C.; Prosperetti, A.; Lohse, D.

    2013-06-01

    The impact of a drop onto a deep bath of an immiscible liquid is studied with emphasis on the drop fragmentation into a collection of noncoalescing daughter drops. At impact the drop flattens and spreads at the surface of the crater it transiently opens in the bath and reaches a maximum deformation, which gets larger with increasing impact velocity, before surface tension drives its recession. This recession can promote the fragmentation by two different mechanisms: At moderate impact velocity, the drop recession converges to the axis of symmetry to form a jet which then fragments by a Plateau-Rayleigh mechanism. At higher velocity the edge of the receding drop destabilizes and shapes into radial ligaments which subsequently fragment. For this latter mechanism the number N∝We3 and the size distribution of the daughter drops p(d)∝d-4 as a function of the impact Weber number We are explained on the basis of the observed spreading of the drop. The universality of this model for the fragmentation of receding liquid sheets might be relevant for other configurations.

  7. Zener Pinning of Grain Boundaries and Structural Stability of Immiscible Alloys

    NASA Astrophysics Data System (ADS)

    Koju, R. K.; Darling, K. A.; Kecskes, L. J.; Mishin, Y.

    2016-06-01

    Immiscible Cu-Ta alloys produced by mechanical alloying are currently the subject of intensive research due to their mechanical strength combined with extraordinary structural stability at high temperatures. Previous experimental and simulation studies suggested that grain boundaries (GBs) in Cu-Ta alloys are stabilized by Ta nano-clusters coherent with the Cu matrix. To better understand the stabilization effect of Ta, we performed atomistic computer simulations of GB-cluster interactions in Cu-Ta alloys with various compositions and GB velocities. The study focuses on a single plane GB driven by an applied shear stress due to the shear-coupling effect. The results of the simulations are in close quantitative agreement with the Zener model of GB pinning. This agreement and the large magnitude of the unpinning stress confirm that the structural stability of these alloys is due to the drastically decreased GB mobility rather than a reduction in GB energy. For comparison, we simulated GB motion in a random solid solution. While the latter also reduces the GB mobility, the effect is not as strong as in the presence of Ta clusters. GB motion in the random solution itself induces precipitation of Ta clusters due to short-circuit diffusion of Ta in GBs, suggesting a possible mechanism of cluster formation inside the grains.

  8. Solution of the equations for one-dimensional, two-phase, immiscible flow by geometric methods

    NASA Astrophysics Data System (ADS)

    Ivan, Boronin; Andrey, Shevlyakov

    2016-12-01

    Buckley-Leverett equations describe non viscous, immiscible, two-phase filtration, which is often of interest in modelling of oil production. For many parameters and initial conditions, the solutions of these equations exhibit non-smooth behaviour, namely discontinuities in form of shock waves. In this paper we obtain a novel method for the solution of Buckley-Leverett equations, which is based on geometry of differential equations. This method is fast, accurate, stable, and describes non-smooth phenomena. The main idea of the method is that classic discontinuous solutions correspond to the continuous surfaces in the space of jets - the so-called multi-valued solutions (Bocharov et al., Symmetries and conservation laws for differential equations of mathematical physics. American Mathematical Society, Providence, 1998). A mapping of multi-valued solutions from the jet space onto the plane of the independent variables is constructed. This mapping is not one-to-one, and its singular points form a curve on the plane of the independent variables, which is called the caustic. The real shock occurs at the points close to the caustic and is determined by the Rankine-Hugoniot conditions.

  9. Satellite formation during bubble transition through an interface between immiscible liquids

    NASA Astrophysics Data System (ADS)

    Li, Erqiang; Al-Otaibi, Shabbab; Vakarelski, Ivan; Thoroddsen, Sigurdur

    2014-11-01

    A bubble can pass through the interface between two immiscible liquids if it is energetically favourable. Once the intermediate film has drained sufficiently, the bubble makes contact with the interface, forming a triple-line and producing strong capillary waves which travel around the bubble and can pinch off a satellite on the opposite side, akin to the coalescence cascade dynamics. We identify the critical Ohnesorge number where such satellites are produced and characterize their sizes. The total transition time scales with the bubble size and differential surface tension, while the satellite pinch-off time scales with the capillary-inertial time of the pool liquid which originally surrounds the bubble. We also use high-speed video imaging to study the contact neck motion. For low viscosity it grows in time with a power-law exponent between 0.44 and 0.50, with a prefactor modified by the net sum of the three interfacial tensions. Increasing the receiving drop viscosity drastically slows down the triple-line motion, when the Ohnesorge number exceeds around 0.08. This differs qualitatively from the coalescence of two miscible drops of different viscosities, where the lower viscosity sets the coalescence speed. We thereby propose a strong resistance from the triple-line.

  10. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    SciTech Connect

    Chen, Youxing; Li, Nan; Bufford, Daniel Charles; Li, Jin; Hattar, Khalid Mikhiel; Wang, Haiyan; Zhang, Xinghang

    2016-04-09

    By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electron microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.

  11. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    DOE PAGES

    Chen, Youxing; Li, Nan; Bufford, Daniel Charles; ...

    2016-04-09

    By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electronmore » microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.« less

  12. Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network

    NASA Astrophysics Data System (ADS)

    Liu, Haihu; Zhang, Yonghao; Valocchi, Albert J.

    2015-05-01

    Injection of anthropogenic carbon dioxide (CO2) into geological formations is a promising approach to reduce greenhouse gas emissions into the atmosphere. Predicting the amount of CO2 that can be captured and its long-term storage stability in subsurface requires a fundamental understanding of multiphase displacement phenomena at the pore scale. In this paper, the lattice Boltzmann method is employed to simulate the immiscible displacement of a wetting fluid by a non-wetting one in two microfluidic flow cells, one with a homogeneous pore network and the other with a randomly heterogeneous pore network. We have identified three different displacement patterns, namely, stable displacement, capillary fingering, and viscous fingering, all of which are strongly dependent upon the capillary number (Ca), viscosity ratio (M), and the media heterogeneity. The non-wetting fluid saturation (Snw) is found to increase nearly linearly with logCa for each constant M. Increasing M (viscosity ratio of non-wetting fluid to wetting fluid) or decreasing the media heterogeneity can enhance the stability of the displacement process, resulting in an increase in Snw. In either pore networks, the specific interfacial length is linearly proportional to Snw during drainage with equal proportionality constant for all cases excluding those revealing considerable viscous fingering. Our numerical results confirm the previous experimental finding that the steady state specific interfacial length exhibits a linear dependence on Snw for either favorable (M ≥ 1) or unfavorable (M < 1) displacement, and the slope is slightly higher for the unfavorable displacement.

  13. Miscible and immiscible liquid experiments and simulations on the Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Roberts, Michael; Mokler, Matthew; Cabot, William; Jacobs, Jeffrey

    2011-11-01

    Experiments and numerical simulations are presented in which an incompressible system of two liquids is accelerated to produce the Rayleigh-Taylor instability. In these experiments, the initially stable, stratified liquid combination is accelerated downward on a vertical rail system in one of two experimental apparatuses: an apparatus in which a system of weights and pulleys accelerates the liquid filled tank (which is affixed to a test sled), or a new apparatus which uses linear induction motors to accelerate the tank (which is attached to an aluminum plate) to produce much greater acceleration levels. Both miscible and immiscible liquid combinations are used. In both apparatuses the resulting fluid flows are visualized with backlit imaging using LED backlights in conjunction with monochrome high-speed video cameras, both of which travel with the moving fluid filled containers. Initial perturbations are either unforced and allowed to progress from background noise or forced by vertically oscillating the liquid combination to produce parametric internal waves. The results of these experiments are compared to numerical simulations performed using the CFD code Miranda.

  14. Heat transfer between immiscible liquids enhanced by gas bubbling. [PWR; BWR

    SciTech Connect

    Greene, G.A.; Schwarz, C.E.; Klages, J.; Klein, J.

    1982-08-01

    The phenomena of core-concrete interactions impact upon containment integrity of light water reactors (LWR) following postulated complete meltdown of the core by containment pressurization, production of combustible gases, and basemat penetration. Experiments have been performed with non-reactor materials to investigate one aspect of this problem, heat transfer between overlying immiscible liquids whose interface is disturbed by a transverse non-condensable gas flux emanating from below. Hydrodynamic studies have been performed to test a criterion for onset of entrainment due to bubbling through the interface and subsequent heat transfer studies were performed to assess the effect of bubbling on interfacial heat transfer rates, both with and without bubble induced entrainment. Non-entraining interfacial heat transfer data with mercury-water/oil fluid pairs were observed to be bounded from below within a factor of two to three by the Szekeley surface renewal heat transfer model. However heat transfer data for fluid pairs which are found to entrain (water-oil), believed to be characteristic of molten reactor core-concrete conditions, were measured to be up to two orders of magnitude greater than surface renewal predictions and are calculated by a simple entrainment heat transfer model.

  15. Stable Superwetting Meshes for On-Demand Separation of Immiscible Oil/Water Mixtures and Emulsions.

    PubMed

    Liu, Mingming; Hou, Yuanyuan; Li, Jing; Guo, Zhiguang

    2017-03-27

    Oil-water separation is of great importance for the treatment of oily wastewater, including immiscible light/heavy oil-water mixtures, oil-in-water or water-in-oil emulsions. Recently, interfacial materials (especially filtration membranes) with special wettability have been broadly developed to solve the environmental problems by virtue of their advantages in energy saving, high flux and good selectivity. However, the given wetting property (superhydrophilicity or superhydrophobicity) and pore size and poor stability of filtration membranes limit their widespread applications, which is far from meeting a wide variety of oil polluted water. Here polypyrrole-coated meshes with underwater superoleophobicity and underoil superhydrophobicity as well as controllable pore size were prepared by adopting cyclic voltammetry. It is found that the surface micro-/nanohierarchical structures play a critical role in the formation of underwater superoleophobicity and underoil superhydrophobicity. HCl is advantageous to the construction of highly rough surface rather than H2SO4 and H3PO4. The obtained filtration membranes can be used for the on-demand separation of oil-water mixtures, showing outstanding stability in harsh conditions, such as high temperature (80 ºC), low temperature (0 ºC), salt (0.5 M NaCl) and acid (1 M HCl), except for alkali (1 M NaOH).

  16. Electrochemical behaviour and voltammetric sensitivity at arrays of nanoscale interfaces between immiscible liquids.

    PubMed

    Rimboud, Mickaël; Hart, Robert D; Becker, Thomas; Arrigan, Damien W M

    2011-11-21

    Arrays of nanoscale interfaces between immiscible electrolyte solutions were formed using silicon nitride nanopore array membranes. Nanopores in the range from 75 nm radius down to 17 nm radius were used to form the nano-interfaces. It was found that the liquid organic phase electrolyte solution filled the pores so that inlaid nano-interfaces were formed with the aqueous phase. Cyclic voltammetry at these nano-interface arrays demonstrated steady-state behaviour at the larger interfaces but the voltammetric wave-shape became progressively worse as the interface size decreased. It was found that the ion transfer currents were ca. 50% of those expected based on theoretical calculations, which is attributed to overlap of diffusion zones at adjacent nano-interfaces. Here, the separation between adjacent nano-interfaces was 20-times the interface radius. The analytical sensitivity for ion transfer from the aqueous to the 1,6-dichlorohexane organic phase was estimated from calibration plots of current density versus concentration of aqueous tetraethylammonium cation. The sensitivity was in the range of 65 μA cm(-2) μM(-1) (at 75 nm radius interfaces) to 265 μA cm(-2) μM(-1) (at 17 nm radius interfaces). The sensitivity depended directly on the inverse of the nano-interface radius, implying that smaller interfaces will provide better sensitivity, due to the enhanced flux of analyte arising from convergent diffusion to smaller electrochemical interfaces.

  17. SPAR 5 experiment no. 74-30 agglomeration in immiscible liquids

    NASA Technical Reports Server (NTRS)

    Gelles, S.; Markworth, A. J.

    1979-01-01

    The influence of gravity, cooling rate, and composition on the macro-and microstructure of liquid phase immiscible alloys were researched. Aluminum indium alloys of compositions 30, 40, 70, and 90 weight percent indium were processed aboard two sounding rocket flights, SPAR 2 and SPAR 5. Radiographic and metallographic examination of the SPAR 2 flight and ground base samples showed the expected separation at lg of the ground base alloys into indium rich and aluminum rich layers. The flight alloys produced an aluminum rich core surrounding by indium rich metal. The results obtained from the SPAR 5 40 and 70 weight percent indium alloys were essentially identical to those from SPAR 2. The 30 and 90 weight percent indium alloys also showed massive separation into configuration similar to the 40 and 70 weight percent indium alloys. The 90 weight percent indium alloy showed additional evidence that surface tension induced droplet migration had occurred in this alloy which could at least in part account for the observed structures.

  18. Miscible and immiscible liquid experiments and simulations on the Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Roberts, Michael; Jacobs, Jeffrey; Cabot, William

    2010-11-01

    Experiments and numerical simulations are presented in which an incompressible system of two liquids is accelerated to produce the Rayleigh-Taylor instability. In these experiments, the initially stable, stratified liquid combination is accelerated downward in one of two experimental apparatuses: a weight and pulley system in which a fluid filled container is accelerated on a rail system, or a new LIM apparatus which uses linear induction motors to accelerate the tank (which is attached to an aluminum plate) to produce much greater acceleration levels. Both miscible and immiscible liquid combinations are used. In both apparatuses the resulting fluid flows are visualized with backlit imaging using LED backlights in conjunction with monochrome high-speed video cameras, both of which travel with the moving fluid filled containers. Initial perturbations are either unforced and allowed to progress from background noise or forced by vertically oscillating the liquid combination to produce parametric internal waves. The results experiments are compared to numerical simulations performed using the CFD code Miranda.

  19. Effect of elongational flow on immiscible polymer blend/nanoparticle composites: a molecular dynamics study.

    PubMed

    Shebert, George L; Lak Joo, Yong

    2016-07-13

    Using coarse-grained nonequilibrium molecular dynamics, the dynamics of a blend of the equal ratio of immiscible polymers mixed with nanoparticles (NP) are simulated. The simulations are conducted under planar elongational flow, which affects the dispersion of the NPs and the self-assembly morphology. The goal of this study is to investigate the effect of planar elongational flow on the nanocomposite blend system as well as to thoroughly compare the blend to an analogous symmetric block copolymer (BCP) system to understand the role of the polymer structure on the morphology and NP dispersion. Two types of spherical NPs are considered: (1) selective NPs that are attracted to one of the polymer components and (2) nonselective NPs that are neutral to both components. A comparison of the blend and BCP systems reveals that for selective NP, the blend system shows a much broader NP distribution in the selective phase than the BCP phase. This is due to a more uniform distribution of polymer chain ends throughout the selective phase in the blend system than the BCP system. For nonselective NP, the blend and BCP systems show similar results for low elongation rates, but the NP peak in the BCP system broadens as elongation rates approach the order-disorder transition. In addition, the presence of NP is found to affect the morphology transitions of both the blend and BCP systems, depending on the NP type.

  20. Interfacial dynamics of two immiscible fluids in spatially periodic porous media: The role of substrate wettability

    NASA Astrophysics Data System (ADS)

    Mondal, Pranab Kumar; DasGupta, Debabrata; Chakraborty, Suman

    2014-07-01

    We delineate the contact line dynamics of two immiscible fluids in a medium having spatially periodic porous structures. The flow is driven by an external applied pressure gradient. We bring out the combined consequences of the solid fraction distribution and the substrate wettability on the resulting dynamics of the contact line, by employing phase-field formalism. We capture the sequence of spatiotemporal events leading to formation of liquid bridges by trapping a small amount of displaced phase fluid between two consecutive porous blocks, as dictated by the combinations of substrate wettability and solid fraction. We also demonstrate the existence of a regime of complete interfacial recovery, depending on the parametric space of the governing parameters under concern. Our results essentially demonstrate the intricate mechanisms by virtue of which the wettabilities of the substrates alter the dynamical evolutions of interfaces and the subsequent shapes and sizes of the adsorbed dispersed phases, bearing far-ranging consequences in several practical applications ranging from oil recovery to groundwater flow.

  1. Getting in shape: molten wax drop deformation and solidification at an immiscible liquid interface.

    PubMed

    Beesabathuni, Shilpa N; Lindberg, Seth E; Caggioni, Marco; Wesner, Chris; Shen, Amy Q

    2015-05-01

    The controlled production of non-spherical shaped particles is important for many applications such as food processing, consumer goods, adsorbents, drug delivery, and optical sensing. In this paper, we investigated the deformation and simultaneous solidification of millimeter size molten wax drops as they impacted an immiscible liquid interface of higher density. By varying initial temperature and viscoelasticity of the molten drop, drop size, impact velocity, viscosity and temperature of the bath fluid, and the interfacial tension between the molten wax and bath fluid, spherical molten wax drops impinged on a cooling water bath and were arrested into non-spherical solidified particles in the form of ellipsoid, mushroom, disc, and flake-like shapes. We constructed cursory phase diagrams for the various particle shapes generated over a range of Weber, Capillary, Reynolds, and Stefan numbers, governed by the interfacial, inertial, viscous, and thermal effects. We solved a simplified heat transfer problem to estimate the time required to initiate the solidification at the interface of a spherical molten wax droplet and cooling aqueous bath after impact. By correlating this time with the molten wax drop deformation history captured from high speed imaging experiments, we elucidate the delicate balance of interfacial, inertial, viscous, and thermal forces that determine the final morphology of wax particles. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Immiscible poly(lactic acid)/poly(ε-caprolactone) for temporary implants: Compatibility and cytotoxicity.

    PubMed

    Finotti, Pablo F M; Costa, Lidiane C; Capote, Ticiana S O; Scarel-Caminaga, Raquel M; Chinelatto, Marcelo A

    2017-01-31

    This manuscript focuses on the effect of the addition of a low molecular weight triblock copolymer derived from ε-caprolactone and tetrahydrofuran (CT) on the compatibility and cytotoxicity of immiscible poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) blends. Binary and tertiary PLA/PCL blends were prepared by melt mixing in a twin-screw extruder and their morphological, mechanical and thermal behaviors were investigated by scanning electron microscopy (SEM), tensile and Izod impact test, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). SEM micrographs showed the CT copolymer suppressed the coalescence phenomena and maintained the size of dispersed PCL domains at approximately 0.35µm. Bioresorbable PLA/PCL blends containing 5wt% of CT copolymer exhibited a remarkable increase in ductility and improved toughness at room temperature. Although the CT copolymer increased the interfacial adhesion, the DMA results suggest it also acts as a plasticizer exclusively for the PCL phase. The cell viability evaluated by the XTT assay confirmed PLA/PCL blends compatibilized by CT copolymer exerted no cytotoxic effect.

  3. Stability analysis of two immiscible fluids in a shear driven flow: a DNS study

    NASA Astrophysics Data System (ADS)

    Garcia Cartagena, Edgardo J.; Bernardini, Matteo; Arenas, Isnardo; Mohammadi, Alireza; Iungo, G. Valerio; Smits, Alexander J.; Leonardi, Stefano

    2016-11-01

    Numerical studies of the flow over either super hydrophobic surfaces or liquid infused surfaces have shown that a large drag reduction (>10%) can be obtained if the flow remains in the Cassie state, thus stability of the interface plays a crucial role to achieve drag reduction. Direct Numerical Simulations of two immiscible fluids have been performed to assess how the stability of the interface depends on the viscosity ratio, thickness and Reynolds number of the two-layer flow. The flow is driven by the motion of one plate at constant velocity while the other plate is at rest. A finite difference code, based on a Runge-Kutta and fractional step method, has been combined to a level set method for tracking the interface between the two fluids. Results agree well with the linear theory until the nonlinear saturation. Once the fluctuations become large, a halving of the wavelength in the streamwise direction is observed for the least stable mode. The interaction between Tollmien-Schlichting waves and interfacial instabilities will be discussed at the meeting. This work was supported under ONR MURI Grants N00014-12-0875 and N00014-12-1-0962, Program Manager Dr. Ki-Han Kim. Numerical simulations were performed on the Texas Advanced Computer Center.

  4. 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.

  5. Flow of immiscible ferrofluids in a planar gap in a rotating magnetic field

    SciTech Connect

    Sule, Bhumika; Torres-Díaz, Isaac; Rinaldi, Carlos

    2015-07-15

    Analytical solutions are obtained for the steady, fully developed flow of two layers of immiscible ferrofluids of different thicknesses between two parallel plates. Interfacial linear and internal angular momentum balance relations are derived for the case when there is a ferrofluid-ferrofluid interface to obtain the translational and spin velocity profiles in the gap. As expected for the limit of low applied field amplitude, the magnitude of the translational velocity is directly proportional to the frequency of the applied magnetic field and to the square of the magnetic field amplitude. Expressions for the velocity profiles are obtained for the zero spin viscosity and non-zero spin viscosity cases and the effect of applied pressure gradient on the flows is studied. The spin velocity in both ferrofluid phases is in the direction of the rotating magnetic field, except for cases of extreme applied pressure gradients for which the fluid vorticity opposes the spin. We find that for the case of non-zero spin viscosity, flow reversals are predicted using representative ferrofluid property values and field conditions. The unique predictions of the solution with non-zero spin viscosity could be used to experimentally test the existence of couple stresses in ferrofluids and the validity of previously reported values of the so-called spin viscosity.

  6. Immiscible fluids in mixed wet porous media: the role of wettability correlations

    NASA Astrophysics Data System (ADS)

    Murison, Julie; Semin, Benoit; Baret, Jean-Christophe; Herminghaus, Stephan; Schroeter, Matthias; Brinkmann, Martin

    2013-11-01

    Various phenomena observed during immiscible displacement in a porous medium can be related to pore wall wettability. Petroleum engineers traditionally quantify the overall wettability of a rock sample in terms of the Ammot-Harvey or USBM index. To establish a link between these gloabl quantities and the pore-scale distribution of surface energies, we developed a series of model porous media. Using a variety of preparation methods, we are able to create dense beds of glass beads with the same average surface energy, differing only in the typical extension of the wetting and non-wetting surface domains. Experimental measurements of capillary pressure saturation curves for repeated imbibition and drainage show that the work dissipated in a complete cycle is monotonically increasing with the correlation length ξ of the surface energies. To test whether capillary hysteresis can be linked to specific features of the front morphology, we visualized the distribution of liquids by means of X-ray microtomography. The Minkowski measures volume, surface area, and Euler number are employed to characterize the interfacial shape. Differences of the front morphology during imbibition and drainage match with trends observed for the hysteresis loop opening.

  7. Low-frequency dilatational wave propagation through unsaturated porous media containing two immiscible fluids

    SciTech Connect

    Lo, W.-C.; Sposito, G.; Majer, E.

    2007-02-01

    An analytical theory is presented for the low-frequency behavior of dilatational waves propagating through a homogeneous elastic porous medium containing two immiscible fluids. The theory is based on the Berryman-Thigpen-Chin (BTC) model, in which capillary pressure effects are neglected. We show that the BTC model equations in the frequency domain can be transformed, at sufficiently low frequencies, into a dissipative wave equation (telegraph equation) and a propagating wave equation in the time domain. These partial differential equations describe two independent modes of dilatational wave motion that are analogous to the Biot fast and slow compressional waves in a single-fluid system. The equations can be solved analytically under a variety of initial and boundary conditions. The stipulation of 'low frequency' underlying the derivation of our equations in the time domain is shown to require that the excitation frequency of wave motions be much smaller than a critical frequency. This frequency is shown to be the inverse of an intrinsic time scale that depends on an effective kinematic shear viscosity of the interstitial fluids and the intrinsic permeability of the porous medium. Numerical calculations indicate that the critical frequency in both unconsolidated and consolidated materials containing water and a nonaqueous phase liquid ranges typically from kHz to MHz. Thus engineering problems involving the dynamic response of an unsaturated porous medium to low excitation frequencies (e.g. seismic wave stimulation) should be accurately modeled by our equations after suitable initial and boundary conditions are imposed.

  8. Beating the Miscibility Barrier between Iron Group Elements and Magnesium by High-Pressure Alloying

    SciTech Connect

    Dubrovinskaia, N.; Dubrovinsky, L.; Kantor, I.; Crichton, W. A.; Dmitriev, V.; Prakapenka, V.; Shen, G.; Vitos, L.; Johansson, B.; Ahuja, R.; Abrikosov, I. A.

    2005-12-09

    Iron and magnesium are almost immiscible at ambient pressure. The low solubility of Mg in Fe is due to a very large size mismatch between the alloy components. However, the compressibility of Mg is much higher than that of Fe, and therefore the difference in atomic sizes between elements decreases dramatically with pressure. Based on the predictions of ab initio calculations, we demonstrate in a series of experiments in a multianvil apparatus and in electrically and laser-heated diamond anvil cells that high pressure promotes solubility of magnesium in iron. At the megabar pressure range, more than 10 at. % of Mg can dissolve in Fe and then the alloy can be quenched to ambient conditions. A generality of the concept of high-pressure alloying between immiscible elements is demonstrated by its application to two other Fe group elements, Co and Ni.

  9. Large-scale liquid immiscibility at the top of the Bushveld Complex

    NASA Astrophysics Data System (ADS)

    VanTongeren, J. A.; Mathez, E. A.

    2011-12-01

    Detailed study of the top 625 m of the Bushveld Complex has revealed two distinct sections of cumulate rocks, the contact between which occurs over a limited stratigraphic range (< 50 m). The ~300 m-thick lower section consists of magnetite-bearing ferrodiorite with cumulus olivine Fo30, plagioclase An45, clinopyroxene En35 and several intercolated layers of magnetitite and nelsonite (apatite- Fe-Ti oxide rocks). In situ analysis shows that cumulus apatite in the lower section contains relatively low REE concentrations and no chondrite-normalized Eu anomaly. In contrast, overlying ~325 m-thick section consists of ferrodioritie cumulates (olivine Fo12-5, plagioclase An40, clinopyroxene En25-10) but contains much less magnetite, more ilmenite, and cumulus orthoclase and quartz. In addition, cumulus apatite of the upper section displays 3x higher REE concentrations than apatite of the lower section and a strong negative Eu anomaly. To explain the above observations, we propose that large-scale silicate liquid immiscibility resulted in the physical separation of a dense, Fe-rich magma to form the lower part of the sequence and a buoyant Si-rich magma to form the upper part of the sequence. This hypothesis is consistent not only with the change in proportions of cumulus phases but also the abrupt change in apatite REE contents. Liquid-liquid partitioning experiments have shown that during immiscibility the Fe-rich liquid will take up to 3-5 times more REE than the Si-rich liquid (Watson, 1976 Contrib. to Min. and Pet. vol. 56, p. 119-134). Yet the cumulus apatite in the lower section has relatively low REE concentrations and the apatite in the upper section has approximately 3x higher REE. This apparent discrepancy can be explained by the high sensitivity of the apatite-melt DREE to the SiO2 content of the liquid (with low DREE for low SiO2 melts, and high DREE for highly silicic melts) (Watson and Green, 1981 EPSL v. 56, p. 405-421). Applying a low DREE appropriate for

  10. Interfacial tension measurement of immiscible liq uids using a capillary tube

    NASA Technical Reports Server (NTRS)

    Rashidnia, N.; Balasubramaniam, R.; Delsignore, D.

    1992-01-01

    The interfacial tension of immiscible liquids is an important thermophysical property that is useful in the behavior of liquids both in microgravity (Martinez et al. (1987) and Karri and Mathur (1988)) and in enhanced oil recovery processes under normal gravity (Slattery (1974)). Many techniques are available for its measurement, such as the ring method, drop weight method, spinning drop method, and capillary height method (Adamson (1960) and Miller and Neogi (1985)). Karri and Mathur mention that many of the techniques use equations that contain a density difference term and are inappropriate for equal density liquids. They reported a new method that is suitable for both equal and unequal density liquids. In their method, a capillary tube forms one of the legs of a U-tube. The interfacial tension is related to the heights of the liquids in the cups of the U-tube above the interface in the capillary. Our interest in this area arose from a need to measure small interfacial tension (around 1 mN/m) for a vegetable oil/silicon oil system that was used in a thermocapillary drop migration experiment (Rashidnia and Balasubramaniam (1991)). In our attempts to duplicate the method proposed by Karri and Mathur, we found it quite difficult to anchor the interface inside the capillary tube; small differences of the liquid heights in the cups drove the interface out of the capillary. We present an alternative method using a capillary tube to measure the interfacial tensions of liquids of equal or unequal density. The method is based on the combined capillary rises of both liquids in the tube.

  11. Detaching droplets in immiscible fluids from a solid substrate with the help of electrowetting.

    PubMed

    Hong, Jiwoo; Lee, Sang Joon

    2015-02-07

    The detachment (or removal) of droplets from a solid surface is an indispensable process in numerous practical applications which utilize digital microfluidics, including cell-based assay, chip cooling, and particle sampling. When a droplet that is fully stretched by impacting or electrowetting is released, the conversion of stored surface energy to kinetic energy can lead to the departure of the droplet from a solid surface. Here we firstly detach sessile droplets in immiscible fluids from a hydrophobic surface by electrowetting. The physical conditions for droplet detachment depend on droplet volume, viscosity of ambient fluid, and applied voltage. Their critical conditions are determined by exploring the retracting dynamics for a wide range of driving voltages and physical properties of fluids. The relationships between physical parameters and dynamic characteristics of retracting and jumping droplets, such as contact time and jumping height, are also established. The threshold voltage for droplet detachment in oil with high viscosity is largely reduced (~70%) by electrowetting actuations with a square pulse. To examine the applicability of three-dimensional digital microfluidic (3D-DMF) platforms to biological applications such as cell culture and cell-based assays, we demonstrate the detachment of droplets containing a mixture of human umbilical vein endothelial cells (HUVECs) and collagen (concentration of 4 × 10(4) cells mL(-1)) in silicone oil with a viscosity of 0.65 cSt. Furthermore, to complement the technical limitations due to the use of a needle electrode and to demonstrate the applicability of the 3D-DMF platform with patterned electrodes to chemical analysis and synthesis, we examine the transport, merging, mixing, and detachment of droplets with different pH values on the platform. Finally, by using DC and AC electrowetting actuations, we demonstrate the detachment of oil droplets with a very low contact angle (<~13°) in water on a hydrophobic

  12. Simulation of three-dimensional flow of immiscible fluids within and below the unsaturated zone

    NASA Astrophysics Data System (ADS)

    Faust, Charles R.; Guswa, John H.; Mercer, James W.

    1989-12-01

    This paper presents a two-phase flow model based on a three-dimensional, finite-difference formulation. As three-dimensional simulations can require substantial computer effort, a numerical technique that takes advantage of vector and parallel processing computer architecture is developed. The model is posed in terms of water saturation and nonwetting fluid pressure. It uses three-phase capillary pressure and relative permeability relationships to permit simulation within or below the unsaturated zone. A modified formulation of slice successive overtaxation (an iterative matrix solution technique) is introduced. This technique is designed to use parallel processing capabilities of new computers. The model is applied to immiscible fluid flow at two chemical waste landfills near Niagara Falls, New York. At both sites, denser than water, nonaqueous liquids (NAPLs) are present in the groundwater regimes in relatively large quantities. The model applications address several technical concerns at the two sites, including the effectiveness of clay as a geologic barrier to NAPL migration owing to capillary pressure forces, the three-dimensional aspects of dense NAPL flow, and the sensitivity of NAPL recovery in pumping wells due to various hydrogeologic and fluid properties. The results of the applications show that (1) even under a downward hydraulic gradient, natural differences in capillary pressure relationships for different lithologies can prevent downward migration of NAPL, (2) without any lithologic-capillary barrier, an upward hydraulic gradient induced by a de watering system can prevent downward migration of NAPL, (3) NAPL recovery at wells is sensitive to relative permeability, a relationship that requires field calibration in many settings, and (4) the three-dimensional aspects of two-phase flow and hydrogeologic heterogeneity require explicit treatment in many settings.

  13. Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network

    SciTech Connect

    Liu, Haihu; Zhang, Yonghao; Valocchi, Albert J.

    2015-05-15

    Injection of anthropogenic carbon dioxide (CO{sub 2}) into geological formations is a promising approach to reduce greenhouse gas emissions into the atmosphere. Predicting the amount of CO{sub 2} that can be captured and its long-term storage stability in subsurface requires a fundamental understanding of multiphase displacement phenomena at the pore scale. In this paper, the lattice Boltzmann method is employed to simulate the immiscible displacement of a wetting fluid by a non-wetting one in two microfluidic flow cells, one with a homogeneous pore network and the other with a randomly heterogeneous pore network. We have identified three different displacement patterns, namely, stable displacement, capillary fingering, and viscous fingering, all of which are strongly dependent upon the capillary number (Ca), viscosity ratio (M), and the media heterogeneity. The non-wetting fluid saturation (S{sub nw}) is found to increase nearly linearly with logCa for each constant M. Increasing M (viscosity ratio of non-wetting fluid to wetting fluid) or decreasing the media heterogeneity can enhance the stability of the displacement process, resulting in an increase in S{sub nw}. In either pore networks, the specific interfacial length is linearly proportional to S{sub nw} during drainage with equal proportionality constant for all cases excluding those revealing considerable viscous fingering. Our numerical results confirm the previous experimental finding that the steady state specific interfacial length exhibits a linear dependence on S{sub nw} for either favorable (M ≥ 1) or unfavorable (M < 1) displacement, and the slope is slightly higher for the unfavorable displacement.

  14. The immiscible cholesterol bilayer domain exists as an integral part of phospholipid bilayer membranes

    PubMed Central

    Raguz, Marija; Mainali, Laxman; Widomska, Justyna; Subczynski, Witold K.

    2011-01-01

    Electron paramagnetic resonance (EPR) spin-labeling methods were used to study the organization of cholesterol and phospholipids in membranes formed from Chol/POPS (cholesterol/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine) mixtures, with mixing ratios from 0 to 3. It was confirmed using the discrimination by oxygen transport and polar relaxation agent accessibility methods that the immiscible cholesterol bilayer domain (CBD) was present in all of the suspensions when the mixing ratio exceeded the cholesterol solubility threshold (CST) in the POPS membrane. The behavior of phospholipid molecules was monitored with phospholipid analogue spin labels (n-PCs), and the behavior of cholesterol was monitored with the cholesterol analogue spin labels CSL and ASL. Results indicated that phospholipid and cholesterol mixtures can form a membrane suspension up to a mixing ratio of ~2. Additionally, EPR spectra for n-PC, ASL, and CSL indicated that both phospholipids and cholesterol exist in these suspensions in the lipid-bilayer-like structures. EPR spectral characteristics of n-PCs (spin labels located in the phospholipid cholesterol bilayer, outside the CBD) change with increase in the cholesterol content up to and beyond the CST. These results present strong evidence that the CBD forms an integral part of the phospholipid bilayer when formed from a Chol/POPS mixture up to a mixing ratio of ~2. Interestingly, CSL in cholesterol alone (without phospholipids) when suspended in buffer does not detect formation of bilayer-like structures. A broad, single-line EPR signal is given, similar to that obtained for the dry film of cholesterol before addition of the buffer. This broad, single-line signal is also observed in suspensions formed for Chol/POPS mixtures (as a background signal) when the Chol/POPS ratio is much greater than 3. It is suggested that the EPR spin-labeling approach can discriminate and characterize the fraction of cholesterol that forms the CBD within the

  15. Deformation and Break-up of Suspension Droplets Sheared in an Immiscible Fluid

    NASA Astrophysics Data System (ADS)

    Desse, Melinda; Hill, Sandra E.; Mitchell, John R.; Wolf, Bettina; Budtova, Tatiana

    2008-07-01

    The deformation and break-up behaviour of suspension droplets immersed in an immiscible fluid has not been widely studied albeit such systems are frequently encountered in every day multiphase products such as foods and cosmetics. Starch is a common thickener used in the food industry. Starch suspensions have shown to offer better flavour perception than polymer thickened solutions; a better understanding of their behaviour under flow would be beneficial in terms of advancement on product formulation. Deformation and break-up of a droplet of swollen-in-water starch granules placed in high viscosity silicon oil was visualised using a counter-rotating parallel-plate shear cell. The silicon oil had a high viscosity to induce shear stresses high enough to deform the droplet; it is also transparent and inert towards the studied system. The starch suspension was prepared to have a volume fraction of 100% swollen granules, i.e. that all water was bound within the swollen starch granules. The shear flow behaviour of this starch suspension is characterised by an apparent yield stress, shear-thinning and first normal stress differences. The rheo-optical experiments were conducted as start-up flow experiments applying shear stresses above the apparent yield stress. A constant shear stress throughout the experiment allows a constant viscosity of the droplet and therefore rules out the shear thinning aspect. Analysis showed droplet break-up at critical Capillary numbers close to those reported for Newtonian fluids. The results demonstrate that the droplet break-up behaviour in a complex emulsion system submitted to shear flow may not be fully described by the rheology of the individual phases alone but may require a microstructure component.

  16. Generation of micro- and nano-droplets containing immiscible solutions in view of optical studies

    NASA Astrophysics Data System (ADS)

    Nastasa, V.; Karapantsios, T.; Samaras, K.; Dafnopatidou, E.; Pradines, V.; Miller, R.; Pascu, M. L.

    2010-08-01

    The multiple resistances to treatment, developed by bacteria and malignant tumors require finding alternatives to the existing medicines and treatment procedures. One of them is strengthening the effects of cytostatics by improving the delivery method. Such a method is represented by the use of medicines as micro/nano-droplets. This method can reduce the substance consumption by generating drug micro-droplets incorporated in substances that can favour a faster localization, than the classical mode of medicine administration, to the tumor tissues. This paper contains the results concerning the generation and study of micro/nano-droplets and the generation of micro-droplets with an inner core (medicine) and a thin layer covering it. We have measured the surface tension at water/air interface and water/oil interface for a medicine (Vancomycin) and we have generated and measured droplets of medicine containing a layer of Vitamin A by using a double capillary system. The micro/nano-droplets may be produced by mixing of two immiscible solutions in particular conditions (high rotating speed and/or high pressure difference). For this we have studied the generation of emulsions of vitamin A diluted in sunflower oil and a solution of a surfactant Tween 80 in distilled water. The concentration of surfactant in water was typically 4*10-5M. We have studied in a batch stirred tank system the dependence of the droplet dimensions in emulsion, function of the mixing rotation speed, agitation time and components ratio. The droplet diameters were measured using a Malvern light scattering instrument type Mastersizer Hydro 2000M. We have obtained droplets with diameters smaller than 100 nm; the diameters distribution exhibited a peak at 65 nm.

  17. A multi-flowpath model for the interpretation of immiscible displacement experiments in heterogeneous soil columns.

    PubMed

    Aggelopoulos, C A; Tsakiroglou, C D

    2009-04-01

    This work focuses on the phenomenon of the immiscible two-phase flow of water and oil in saturated heterogeneous soil columns. The goal is to develop a fast and reliable method for quantifying soil heterogeneities for incorporation into the relevant capillary pressure and relative permeability functions. Such data are commonly used as input data in simulators of contaminant transport in the subsurface. Rate-controlled drainage experiments are performed on undisturbed soil columns and the transient response of the axial distribution of water saturation is determined from electrical measurements. The transient responses of the axial distribution of water saturation and total pressure drop are fitted with the multi-flowpath model (MFPM) where the pore space is regarded as a system of parallel paths of different permeability. The MFPM enables us to quantify soil heterogeneity at two scales: the micro-scale parameters describe on average the effects of pore network heterogeneities on the two-phase flow pattern; the macro-scale parameters indicate the variability of permeability at the scale of interconnected pore networks. The capillary pressure curve is consistent with that measured with mercury intrusion porosimetry over the low pressure range. The oil relative permeability increases sharply at a very low oil saturation (<10(-3)) and tends to a high end value. The water relative permeability decreases abruptly at a low oil saturation (~0.1), whereas the irreducible wetting phase saturation is quite high. The foregoing characteristics of the two-phase flow properties are associated with critical (preferential) flowpaths that comprise a very small percentage of the total pore volume, control the overall hydraulic conductivity, and are consistent with the very broad range of pore-length scales usually probed in soil porous matrix.

  18. Physical formulation and numerical algorithm for simulating N immiscible incompressible fluids involving general order parameters

    SciTech Connect

    Dong, S.

    2015-02-15

    We present a family of physical formulations, and a numerical algorithm, based on a class of general order parameters for simulating the motion of a mixture of N (N⩾2) immiscible incompressible fluids with given densities, dynamic viscosities, and pairwise surface tensions. The N-phase formulations stem from a phase field model we developed in a recent work based on the conservations of mass/momentum, and the second law of thermodynamics. The introduction of general order parameters leads to an extremely strongly-coupled system of (N−1) phase field equations. On the other hand, the general form enables one to compute the N-phase mixing energy density coefficients in an explicit fashion in terms of the pairwise surface tensions. We show that the increased complexity in the form of the phase field equations associated with general order parameters in actuality does not cause essential computational difficulties. Our numerical algorithm reformulates the (N−1) strongly-coupled phase field equations for general order parameters into 2(N−1) Helmholtz-type equations that are completely de-coupled from one another. This leads to a computational complexity comparable to that for the simplified phase field equations associated with certain special choice of the order parameters. We demonstrate the capabilities of the method developed herein using several test problems involving multiple fluid phases and large contrasts in densities and viscosities among the multitude of fluids. In particular, by comparing simulation results with the Langmuir–de Gennes theory of floating liquid lenses we show that the method using general order parameters produces physically accurate results for multiple fluid phases.

  19. Modeling of Immiscible, Two-Phase Flows in a Natural Rock Fracture

    SciTech Connect

    Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H

    2009-01-01

    One potential method of geologically sequestering carbon dioxide (CO2) is to inject the gas into brine-filled, subsurface formations. Within these low-permeability rocks, fractures exist that can act as natural fluid conduits. Understanding how a less viscous fluid moves when injected into an initially saturated rock fracture is important for the prediction of CO2 transport within fractured rocks. Our study examined experimentally and numerically the motion of immiscible fluids as they were transported through models of a fracture in Berea sandstone. The natural fracture geometry was initially scanned using micro-computerized tomography (CT) at a fine volume-pixel (voxel) resolution by Karpyn et al. [1]. This CT scanned fracture was converted into a numerical mesh for two-phase flow calculations using the finite-volume solver FLUENT® and the volume-of-fluid method. Additionally, a translucent experimental model was constructed using stereolithography. The numerical model was shown to agree well with experiments for the case of a constant rate injection of air into the initially water-saturated fracture. The invading air moved intermittently, quickly invading large-aperture regions of the fracture. Relative permeability curves were developed to describe the fluid motion. These permeability curves can be used in reservoir-scale discrete fracture models for predictions of fluid motion within fractured geological formations. The numerical model was then changed to better mimic the subsurface conditions at which CO2 will move into brine saturated fractures. The different fluid properties of the modeled subsurface fluids were shown to increase the amount of volume the less-viscous invading gas would occupy while traversing the fracture.

  20. Effects of shear during the cooling on the rheology and morphology of immiscible polymer blends

    NASA Astrophysics Data System (ADS)

    Hammani, S.; Moulai-Mostefa, N.; Benyahia, L.; Tassin, J. F.

    2014-08-01

    The aim of this work was the generation of a microfibrillar structure in immiscible polymer blends using a new technique. The blend polymer model is the emulsion formed by a mixture of polypropylene (PP) with polystyrene (PS) in the proportion of PP10/PS90. In the first case the pellets of polystyrene and polypropylene were blended on the twin-screw mini extruder in the classical manner with different shear rates. In the second case, the same blend was prepared in the same way followed by a dynamic cooling at different shear rates. The phase morphologies of PP in the blend were determined by Scanning Electron Microscopy on two directions (transversal and longitudinal direction to the flow). In the two cases, the dispersed phase size decreased with the increase of the shear rate in the extruder. An anomaly was registered in the classical method at 200 rpm, where the size of the dispersed phase increases with the increase of the shear rate. The dynamic cooling technique recorded smaller diameters (4 to 5 times) of the dispersed phase compared to the conventional technique. In addition, the reappearance of the microfilaments at 200rpm was observed. The rheological properties were determined by RS100 (Thermo Scientific Haake). Using this new technique, it was noticed that he elastic modulus increases with one decade compared to the classical method and the complex viscosity decreases with the increase of the shear rate. An anomaly was registered in the classical technique, where the dynamic viscosity at 200rpm increases with increasing the shear rate in the extruder.

  1. Dynamics of rigid microparticles at the interface of co-flowing immiscible liquids in a microchannel.

    PubMed

    Jayaprakash, K S; Banerjee, U; Sen, A K

    2017-05-01

    We report the dynamical migration behavior of rigid polystyrene microparticles at an interface of co-flowing streams of primary CP1 (aqueous) and secondary CP2 (oils) immiscible phases at low Reynolds numbers (Re) in a microchannel. The microparticles initially suspended in the CP1 either continue to flow in the bulk CP1 or migrate across the interface into CP2, when the stream width of the CP1 approaches the diameter of the microparticles. Experiments were performed with different secondary phases and it is found that the migration criterion depends on the sign of the spreading parameter S and the presence of surfactant at the interface. To substantiate the migration criterion, experiments were also carried out by suspending the microparticles in CP2 (oil phase). Our study reveals that in case of aqueous-silicone oil combination, the microparticles get attached to the interface since S<0 and the three phase contact angle, θ>90°. For complete detachment of microparticles from the interface into the secondary phase, additional energy ΔG is needed. We discuss the role of interfacial perturbation, which causes detachment of microparticles from the interface. In case of mineral and olive oils, the surfactants present at the interface prevents attachment of the microparticles to the interface due to the repulsive disjoining pressure. Finally, using a aqueous-silicone oil system, we demonstrate size based sorting of microparticles of size 25μm and 15μm respectively from that of 15μm and 10μm and study the variation of separation efficiency η with the ratio of the width of the aqueous stream to the diameter of the microparticles ρ.

  2. Semianalytical solutions for cocurrent and countercurrent imbibition and dispersion of solutes in immiscible two-phase flow

    NASA Astrophysics Data System (ADS)

    Schmid, K. S.; Geiger, S.; Sorbie, K. S.

    2011-02-01

    We derive a set of semianalytical solutions for the movement of solutes in immiscible two-phase flow. Our solutions are new in two ways: First, we fully account for the effects of capillary and viscous forces on the transport for arbitrary capillary-hydraulic properties. Second, we fully take hydrodynamic dispersion for the variable two-phase flow field into account. The understanding of immiscible two-phase flow and the simultaneous miscible displacement and mixing of components within a phase is important for many applications, including the location of nonaqueous phase liquids in the subsurface, the design of contaminant cleanup procedures, the sequestration of carbon dioxide, and enhanced oil-recovery techniques. For purely advective transport we combine a known exact solution for the description of immiscible two-phase flow with the method of characteristics for the advective transport equations to obtain solutions that describe cocurrent flow and countercurrent spontaneous imbibition and advective transport in one dimension. We show that for both cases the solute front can be located graphically by a modified Welge tangent. For the advective-dispersive solute transport, we derive approximate analytical solutions by the method of singular perturbation expansion. On the basis of this, we obtain analytical expressions for the growth of the dispersive zone for the case with and without the influence of capillary pressure. We show that for the case of spontaneous countercurrent imbibition the order of magnitude of the growth rate is far smaller than that for the viscous limit. We give some illustrative examples and compare the analytical expressions with numerical reference solutions.

  3. Stochastic analysis of immiscible displacement of the fluids with arbitrary viscosities and its dependence on support scale of hydrological data

    SciTech Connect

    Tartakovsky, Alexandre M.; Meakin, Paul; Huang, Hai

    2004-12-01

    Stochastic analysis is commonly used to address uncertainty in the modeling of flow and transport in porous media. In the stochastic approach, the properties of porous media are treated as random functions with statistics obtained from field measurements. Several studies indicate that hydrological properties depend on the scale of measurements or support scales, but most stochastic analysis does not address the effects of support scale on stochastic predictions of subsurface processes. In this work we propose a new approach to study the scale dependence of stochastic predictions. We present a stochastic analysis of immiscible fluid-fluid displacement in randomly heterogeneous porous media. While existing solutions are applicable only to systems in which the viscosity of one phase is negligible compare with the viscosity of the other (water-air systems for example), our solutions can be applied to the immiscible displacement of fluids having arbitrarily viscosities such as NAPL-water and water-oil. Treating intrinsic permeability as a random field with statistics dependant on the permeability support scale (scale of measurements) we obtained, for one-dimensional systems, analytical solutions for the first moments characterizing unbiased predictions (estimates) of system variables, such as the pressure and fluid-fluid interface position, and we also obtained second moments, which characterize the uncertainties associated with such predictions. Next we obtained empirically scale dependent exponential correlation function of the intrinsic permeability that allowed us to study solutions of stochastic equations as a function of the support scale. We found that the first and second moments converge to asymptotic values as the support scale decreases. In our examples, the statistical moments reached asymptotic values for support scale that were approximately 1/10000 of the flow domain size. We show that analytical moment solutions compare well with the results of Monte

  4. Stochastic Analysis of Immiscible Displacement of the Fluids with Arbitrarily Viscosities and its Dependence on Support Scale of Hydrological Data

    SciTech Connect

    A. M. Tartakovsky; P. Meakin; H. Huang

    2004-12-01

    Stochastic analysis is commonly used to address uncertainty in the modeling of flow and transport in porous media. In the stochastic approach, the properties of porous media are treated as random functions with statistics obtained from field measurements. Several studies indicate that hydrological properties depend on the scale of measurements or support scales, but most stochastic analysis does not address the effects of support scale on stochastic predictions of subsurface processes. In this work we propose a new approach to study the scale dependence of stochastic predictions. We present a stochastic analysis of immiscible fluid–fluid displacement in randomly heterogeneous porous media. While existing solutions are applicable only to systems in which the viscosity of one phase is negligible compare with the viscosity of the other (water–air systems for example), our solutions can be applied to the immiscible displacement of fluids having arbitrarily viscosities such as NAPL–water and water–oil. Treating intrinsic permeability as a random field with statistics dependant on the permeability support scale (scale of measurements) we obtained, for one-dimensional systems, analytical solutions for the first moments characterizing unbiased predictions (estimates) of system variables, such as the pressure and fluid–fluid interface position, and we also obtained second moments, which characterize the uncertainties associated with such predictions. Next we obtained empirically scale dependent exponential correlation function of the intrinsic permeability that allowed us to study solutions of stochastic equations as a function of the support scale. We found that the first and second moments converge to asymptotic values as the support scale decreases. In our examples, the statistical moments reached asymptotic values for support scale that were approximately 1/10000 of the flow domain size. We show that analytical moment solutions compare well with the results of

  5. Rayleigh-Taylor instability for immiscible fluids of arbitrary viscosities: a magnetic levitation investigation and theoretical model.

    PubMed

    Carlès, Pierre; Huang, Zhibin; Carbone, Giovanni; Rosenblatt, Charles

    2006-03-17

    A magnetic field gradient was used to draw down a low density paramagnetic fluid below a more dense fluid in a Hele-Shaw cell. On turning off the field a Rayleigh-Taylor instability was observed in situ, and the growth of the most unstable wave vector was measured versus time. A theory for the instability that permits different viscosities for two immiscible fluids was developed, and good agreement was found with the experimental results. The technique of magnetic levitation promises to broaden significantly the accessible parameter space of gravitational interfacial instability experiments.

  6. Fluid immiscibility and gold deposition in the Birimian quartz veins of the Angovia deposit (Yaouré, Ivory Coast)

    NASA Astrophysics Data System (ADS)

    Coulibaly, Y.; Boiron, M. C.; Cathelineau, M.; Kouamelan, A. N.

    2008-02-01

    The Paleoproterozoic terranes (Birimian) of West Africa are well known to host numerous economic gold mineralizations. The Angovia gold mineralization is located in a brecciated and mylonitic zone within the Birimian greenstones. The sulfide-gold mineralization is mainly represented by gold associated with pyrite and chalcopyrite. A fluid inclusion study undertaken on mineralized quartz veins revealed the presence of aqueous-carbonic (CO 2-H 2O) fluids, the association of carbonic (CO 2) and early aqueous fluids, followed by later aqueous (H 2O-salt) and finally nitrogen-rich fluids. Entrapment of the initial homogeneous aqueous-carbonic fluids prior to fluid immiscibility depicts the evolution of the P-T conditions during the exhumation of the terranes after the peak of green-schist metamorphism. The CO 2 rich-fluid occurs especially in gold-bearing quartz, and are considered as the main evidence of the ore-forming process in the gold-bearing quartz veins. It is considered as a product of immiscibility of the CO 2-H 2O parent. The volatile fraction of carbonic and aqueous-carbonic fluid inclusions is dominated by CO 2, containing minor amounts of N 2, even smaller amounts of CH 4 and sporadically, H 2S. The aqueous-carbonic fluids have moderate salinity (3-10 wt.% eq. NaCl). Late aqueous and N 2 - (CH 4-CO 2) fluids are considered as later, unrelated to the main ore stage, and were trapped during the cooling of the hydrothermal system from 300 to 200 °C. The immiscibility has been favored by a strong pressure drop, the main trapping P-T conditions being 320-370 °C and 105-135 MPa. The mineralizing process is likely related to the immiscibility event, which was probably favored by the release of the fluid pressure after fracturing along the main shear zones. The ore process is likely to have occurred along the main shear zones or related secondary structures affected by cycling of the fluid pressure and quartz sealing-fracturing processes. The superimposed

  7. Morphology and rheology of an immiscible polymer blend subjected to a step electric field under shear flow.

    PubMed

    Orihara, H; Nishimoto, Y; Aida, K; Na, Y H; Nagaya, T; Ujiie, S

    2011-07-20

    We have investigated the structural change of an immiscible polymer blend in shear flow when subjected to a step electric field. During the process three-dimensional images were successfully constructed with a confocal scanning laser microscope and at the same time the transient shear stress was also measured. The interface tensor was calculated from the images. Several factors are incorporated into the shear stress, such as the bulk viscosity, the interfacial tension and the Maxwell stress. We performed an experiment to separate the Maxwell stress from the total shear stress. The results are discussed in terms of the interface tensor.

  8. Can a Difference in Molecular Weights Cause an Eruption in a Driven Flow of Self-Organizing Immiscible System?

    DTIC Science & Technology

    2008-01-01

    currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE IDD-MM-YYYY) 23-01-2008 2 . REPORT TYPE Journal...immiscible system? R.B. Pandey12a and J.F. Gettrust1 1 Naval Research Laboratory, Stennis Space Center, MS 39529, USA 2 Department of Physics and...Published online 23 January 2008 - © EDP Sciences, Societa Italiana di Fisica , Springer-Verlag 2008 Abstract. Driven flow of a non-equilibrium non

  9. Effect of viscosity ratio on the self-sustained instabilities in planar immiscible jets

    NASA Astrophysics Data System (ADS)

    Tammisola, Outi; Loiseau, Jean-Christophe; Brandt, Luca

    2017-03-01

    tension, although dissipative, can induce a velocity field near the interface that extracts energy from the flow through a viscous mechanism. This study highlights the rich dynamics of immiscible planar uniform-density jets, where different self-sustained and convective mechanisms compete and the nature of the instability depends on the exact parameter values.

  10. Time dependence of the mechanical properties of an immiscible polymer blend

    NASA Astrophysics Data System (ADS)

    Lynch, Jennifer Krystyna

    Lifetime of a 35/65 PS/HDPE immiscible polymer blend, IMPB, railroad crosstie was investigated. Predictive techniques were developed to predict creep and stress relaxation behavior from short-term compressive stress-strain experiments, and predicted values were compared with experimental results. The weathering effect on the IMPB mechanical properties and the environmental benefits of replacing chemically treated wood crossties with IMPB crossties were investigated. Creep and stress relaxation experiments were performed under conditions simulating the maximum lateral load acting on a crosstie on a Class 1 railroad, and spike pull out experiments were performed using cut spikes. Cyclic uniaxial compressive creep experiments left nearly no residual strain remaining in the IMPB samples. Experimental results suggest the track gage will not widen more than 1/8 of an inch when IMPB crossties are utilized. Thus, creep and track gage widening do not limit the lifetime of IMPB crossties in track. Uniaxial compressive stress relaxation experiments and spike pull out experiments conducted at various time intervals from the day of installation were performed to illustrate the similarity of a spike pull out force versus time from the day of installation curve and a stress relaxation curve. The force decreases exponentially with time, in both cases. Research determined that spike killing due to biological attack is irrelevant, and there is no evidence of spike killing on any IMPB crossties currently in track. Predicted creep strain and stress relaxation were in good agreement with experimental data. A correlation is drawn between predicted long-term creep behavior for the IMPB and experimental creep behavior of polyethylene over 25 years. Theories developed for this work were determined reasonable and provide an alternative to performing long-term experiments. Natural and accelerated weathering experiments indicated no degradation in IMPB mechanical properties. Accelerated

  11. Evolution of Immiscibly Blended Functionalized Polymers with Respect to Cure Parameters and Formulation

    NASA Astrophysics Data System (ADS)

    Heller, Nicholas Walter Medicus

    Powder coatings are becoming ubiquitous in the coating marketplace due to the absence of solvents in their formulation, but they have yet to see implementation in low-reflectance outdoor applications. This demand could be met by utilizing polymer blends formulated with low loadings of matting agents and pigments. The goal of this research is a thorough characterization of prototype low-reflectance coatings through several analytical techniques. Prototypical thermoset blends consist of functionalized polyurethanes rendered immiscible by differences in polar and hydrogen bonding characteristics, resulting in a surface roughened by droplet domains. Analysis of both pigmented and control clear films was performed. This research project had three primary aims: (1) determine the composition of the resin components of the polymer blend; (2) to monitor the evolution of domains before and during curing of clear polymer blends; (3) to monitor the evolution of these domains when pigments are added to these blends. The clear films enabled unhindered analysis by Fourier transform infrared (FTIR) and Raman spectroscopy on the binder. However, these domains provided no spectroscopic signatures despite their observation by optical microscopy. This necessitated the development of a new procedure for cross-section preparation that leaves no contamination from polishing media, which enabled Raman mapping of the morphology via an introduced marker peak from styrene monomer. The clears were analyzed as a powder and as films that were quenched at various cure-times using FTIR, Raman, transmission electron microscopy (TEM), and thermomechanical methods to construct a model of coating evolution based on cure parameters and polymer dynamics. Domains were observed in the powder, and underwent varying rates of coarsening as the cure progressed. TEM, scanning electron microscopy and thermomechanical methods were also used on pigmented systems at different states of the cure, including in

  12. The immiscible cholesterol bilayer domain exists as an integral part of phospholipid bilayer membranes.

    PubMed

    Raguz, Marija; Mainali, Laxman; Widomska, Justyna; Subczynski, Witold K

    2011-04-01

    Electron paramagnetic resonance (EPR) spin-labeling methods were used to study the organization of cholesterol and phospholipids in membranes formed from Chol/POPS (cholesterol/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine) mixtures, with mixing ratios from 0 to 3. It was confirmed using the discrimination by oxygen transport and polar relaxation agent accessibility methods that the immiscible cholesterol bilayer domain (CBD) was present in all of the suspensions when the mixing ratio exceeded the cholesterol solubility threshold (CST) in the POPS membrane. The behavior of phospholipid molecules was monitored with phospholipid analogue spin labels (n-PCs), and the behavior of cholesterol was monitored with the cholesterol analogue spin labels CSL and ASL. Results indicated that phospholipid and cholesterol mixtures can form a membrane suspension up to a mixing ratio of ~2. Additionally, EPR spectra for n-PC, ASL, and CSL indicated that both phospholipids and cholesterol exist in these suspensions in the lipid-bilayer-like structures. EPR spectral characteristics of n-PCs (spin labels located in the phospholipid cholesterol bilayer, outside the CBD) change with increase in the cholesterol content up to and beyond the CST. These results present strong evidence that the CBD forms an integral part of the phospholipid bilayer when formed from a Chol/POPS mixture up to a mixing ratio of ~2. Interestingly, CSL in cholesterol alone (without phospholipids) when suspended in buffer does not detect formation of bilayer-like structures. A broad, single-line EPR signal is given, similar to that obtained for the dry film of cholesterol before addition of the buffer. This broad, single-line signal is also observed in suspensions formed for Chol/POPS mixtures (as a background signal) when the Chol/POPS ratio is much greater than 3. It is suggested that the EPR spin-labeling approach can discriminate and characterize the fraction of cholesterol that forms the CBD within the

  13. Chaos-assisted formation of immiscible matter-wave solitons and self-stabilization in the binary discrete nonlinear Schrödinger equation

    NASA Astrophysics Data System (ADS)

    Makarov, D. V.; Uleysky, M. Yu.

    2017-02-01

    Binary discrete nonlinear Schrödinger equation is used to describe dynamics of two-species Bose-Einstein condensate loaded into an optical lattice. Linear inter-species coupling leads to Rabi transitions between the species. In the regime of strong nonlinearity, a wavepacket corresponding to condensate separates into localized and ballistic fractions. Localized fraction is predominantly formed by immiscible solitons consisted of only one species. Immiscible solitons are formed from initially non-separated states after transient chaotic regime. We calculate the finite-time Lyapunov exponent as a rate of wavepacket divergence in the Hilbert space. Appearance of immiscible solitons to spontaneous self-stabilization of the wavepacket. It is found that onset of chaos is accompanied by fast variations of interaction energy and energy of inter-site tunneling. Crossover to self-stabilization is accompanied by reduction of condensate density due to emittance of ballistically propagating waves.

  14. In situ synchrotron study of liquid phase separation process in Al-10 wt.% Bi immiscible alloys by radiography and small angle X-ray scattering

    NASA Astrophysics Data System (ADS)

    Lu, W. Q.; Zhang, S. G.; Li, J. G.

    2016-03-01

    Liquid phase separation process of immiscible alloys has been repeatedly tuned to create special structure for developing materials with unique properties. However, the fundamental understanding of the liquid phase separation process is still under debate due to the characteristics of immiscible alloys in opacity and high temperature environment of alloy melt. Here, the liquid phase separation process in solidifying Al-Bi immiscible alloys was investigated by synchrotron radiography and small angle X-ray scattering. We provide the first direct evidence of surface segregation prior to liquid decomposition and present that the time dependence on the number of Bi droplets follows Logistic curve. The liquid decomposition results from a nucleation and growth process rather than spinodal decomposition mechanism because of the positive deviation from Porod's law. We also found that the nanometer-sized Bi-rich droplets in Al matrix melt present mass fractal characteristics.

  15. Substrate-induced epitaxial mixing of bulk-immiscible La5/8Sr3/8MnO3/LuMnO3 films

    NASA Astrophysics Data System (ADS)

    Hur, N.; Cheong, S.-W.; Kale, S. N.; Ogale, S. B.; Choudhary, R.; Shinde, S. R.; Venkatesan, T.

    2005-03-01

    A mixture of a colossal magnetoresistance manganite (La5/8Sr3/8MnO3) and a multiferroic (LuMnO3), of potential interest for magnetoelectronics, was found to be bulk immiscible due to its structural/chemical incompatibility. Here, we demonstrate that thin-film epitaxy offers a route to achieve continuous perovskite solid solutions of such a bulk-immiscible mixture, allowing studies of their physical properties. The films grow with (110)- and (001)-preferred orientation on SrTiO3(100) and LaAlO3(100), respectively. The details of structural, magnetotransport, and magnetization data are discussed within the context of metal-insulator phase coexistence. Epitaxial stabilization of chemically immiscible phases clearly widens the scope of research on manganites as well as other materials.

  16. Composition and size dependence of hydrogen interaction with carbon supported bulk-immiscible Pd-Rh nanoalloys.

    PubMed

    Oumellal, Yassine; Provost, Karine; Ghimbeu, Camelia Matei; de Yuso, Alicia Martinez; Zlotea, Claudia

    2016-11-18

    In-depth clarification of hydrogen interaction with noble metal nanoparticles and nanoalloys is essential for further development and design of efficient catalysts and hydrogen storage nanomaterials. This issue becomes even more challenging for nanoalloys of bulk-immiscible metals. The hydrogen interaction with bulk-immiscible Pd-Rh nanoalloys (3-6 nm) supported on mesoporous carbon is studied by both laboratory and large scale facility techniques. X-ray diffraction (XRD) reveals a single phase fcc structure for all nanoparticles confirming the formation of nanoalloys in the whole composition range. In situ extended x-ray absorption fine structure (EXAFS) experiments suggest segregated local structures into Pd-rich surface and Rh-rich core coexisting within the nanoparticles. Hydrogen sorption can be tuned by chemical composition: Pd-rich nanoparticles form a hydride phase, whereas Rh-rich phases do not absorb hydrogen under ambient temperature and pressure conditions. The thermodynamics of hydride formation can be tailored by the composition without affecting hydrogen capacity at full hydrogenation. Furthermore, for hydrogen absorbing nanoalloys, in situ EXAFS reveals a preferential occupation of hydrogen for the interstitial sites around Pd atoms. To our knowledge, this is the first study providing insights into the hydrogen interaction mechanism with Pd-Rh nanoalloys that can guide the design of catalysts for hydrogenation reactions and the development of nanomaterials for hydrogen storage.

  17. Tailoring the interface of an immiscible polymer blend by a mutually miscible homopolymer grafted onto graphene oxide: outstanding mechanical properties.

    PubMed

    Kar, Goutam Prasanna; Biswas, Sourav; Bose, Suryasarathi

    2015-01-21

    A unique strategy was adopted here to improve the compatibility between the components of an immiscible polymer blend and strengthen the interface. PMMA, a mutually miscible polymer to both PVDF and ABS, improved the compatibility between the phases by localizing at the blends interface. This was supported by the core-shell formation with PMMA as the shell and ABS as the core as observed from the SEM micrographs. This phenomenon was strongly contingent on the concentration of PMMA in the blends. This strategy was further extended to localize graphene oxide (GO) sheets at the blends interface by chemically coupling it to PMMA (PMMA-g-GO). A dramatic increment of ca. 84% in the Young's modulus and ca. 124% in the yield strength was observed in the presence of PMMA-g-GO with respect to the neat blends. A simultaneous increment in both the strength and the modulus was observed in the presence of PMMA-g-GO whereas, only addition of GO resulted in a moderate improvement in the yield strength. This study reveals that a mutually miscible polymer can render compatibility between the immiscible pair and can improve the stress transfer at the interface.

  18. Efficient co-delivery of immiscible hydrophilic/hydrophobic chemotherapeutics by lipid emulsions for improved treatment of cancer.

    PubMed

    Zhang, Bo; Song, Yunmei; Wang, Tianqi; Yang, Shaomei; Zhang, Jing; Liu, Yongjun; Zhang, Na; Garg, Sanjay

    2017-01-01

    Combinational nanomedicine is becoming a topic of much interest in cancer therapy, although its translation into the clinic remains extremely challenging. One of the main obstacles lies in the difficulty to efficiently co-deliver immiscible hydrophilic/hydrophobic drugs into tumor sites. The aim of this study was to develop co-loaded lipid emulsions (LEs) to co-deliver immiscible hydrophilic/hydrophobic drugs to improve cancer therapy and to explore the co-delivery abilities between co-loaded LEs and mixture formulation. Multiple oxaliplatin/irinotecan drug-phospholipid complexes (DPCs) were formulated. Co-loaded LEs were prepared using DPC technique to efficiently encapsulate both drugs. Co-loaded LEs exhibited uniform particle size distribution, desired stability and synchronous release profiles in both drugs. Co-loaded LEs demonstrated superior anti-tumor activity compared with the simple solution mixture and the mixture of single-loaded LEs. Furthermore, co-loaded nanocarriers could co-deliver both drugs into the same cells more efficiently and exhibited the optimized synergistic effect. These results indicate that co-loaded LEs could be a desired formulation for enhanced cancer therapy with potential application prospects. The comparison between co-loaded LEs and mixture formulation is significant for pharmaceutical designs aimed at co-delivery of multiple drugs.

  19. Composition and size dependence of hydrogen interaction with carbon supported bulk-immiscible Pd-Rh nanoalloys

    NASA Astrophysics Data System (ADS)

    Oumellal, Yassine; Provost, Karine; Matei Ghimbeu, Camelia; Martinez de Yuso, Alicia; Zlotea, Claudia

    2016-11-01

    In-depth clarification of hydrogen interaction with noble metal nanoparticles and nanoalloys is essential for further development and design of efficient catalysts and hydrogen storage nanomaterials. This issue becomes even more challenging for nanoalloys of bulk-immiscible metals. The hydrogen interaction with bulk-immiscible Pd-Rh nanoalloys (3-6 nm) supported on mesoporous carbon is studied by both laboratory and large scale facility techniques. X-ray diffraction (XRD) reveals a single phase fcc structure for all nanoparticles confirming the formation of nanoalloys in the whole composition range. In situ extended x-ray absorption fine structure (EXAFS) experiments suggest segregated local structures into Pd-rich surface and Rh-rich core coexisting within the nanoparticles. Hydrogen sorption can be tuned by chemical composition: Pd-rich nanoparticles form a hydride phase, whereas Rh-rich phases do not absorb hydrogen under ambient temperature and pressure conditions. The thermodynamics of hydride formation can be tailored by the composition without affecting hydrogen capacity at full hydrogenation. Furthermore, for hydrogen absorbing nanoalloys, in situ EXAFS reveals a preferential occupation of hydrogen for the interstitial sites around Pd atoms. To our knowledge, this is the first study providing insights into the hydrogen interaction mechanism with Pd-Rh nanoalloys that can guide the design of catalysts for hydrogenation reactions and the development of nanomaterials for hydrogen storage.

  20. Smart candle soot coated membranes for on-demand immiscible oil/water mixture and emulsion switchable separation.

    PubMed

    Li, Jian; Zhao, Zhihong; Li, Dianming; Tian, Haifeng; Zha, Fei; Feng, Hua; Guo, Lin

    2017-09-21

    Oil/water separation is of great importance for the treatment of oily wastewater, including immiscible light/heavy oil-water mixtures, oil-in-water or water-in-oil emulsions. Smart surfaces with responsive wettability have received extensive attention especially for controllable oil/water separation. However, traditional smart membranes with a switchable wettability between superhydrophobicity and superhydrophilicity are limited to certain responsive materials and continuous external stimuli, such as pH, electrical field or light irradiation. Herein, a candle soot coated mesh (CSM) with a larger pore size and a candle soot coated PVDF membrane (CSP) with a smaller pore size with underwater superoleophobicity and underoil superhydrophobicity were successfully fabricated, which can be used for on-demand immiscible oil/water mixtures and surfactants-stabilized oil/water emulsion separation, respectively. Without any continuous external stimulus, the wettability of our membranes could be reversibly switched between underwater superoleophobicity and underoil superhydrophobicity simply by drying and washing alternately, thus achieving effective and switchable oil/water separation with excellent separation efficiency. We believe that such smart materials will be promising candidates for use in the removal of oil pollutants in the future.

  1. Surface Modification Methods to Control Wettability in Immiscible Fluid Displacement Experimental Model Systems Relevant to Geological Carbon Sequestration

    NASA Astrophysics Data System (ADS)

    Grate, J. W.; Warner, M. G.; Oostrom, M.; Zhang, C.; Wietsma, T. W.; Pittman, J. W.; Dehoff, K. J.

    2011-12-01

    Wettability is a critical parameter influencing immiscible fluid displacements relevant to geological carbon sequestration. Fully water-wet clean silica surfaces can be modified with silanes to alter the wettability, with the majority of such efforts to date related to conversions of water-wet to oil-wet systems. While a sizable literature exist on contact angles obtained on silanized surfaces, these are by and large air-water contact angle data, not the oil-water contact angles needed. We have investigated a large range of silanes to modify silica surfaces over a range of wettabilities, measuring both air-water and oil-water contact angles. We have identified surface modifications to produce intermediate wet surfaces. We have found a linear correlation between air-water contact angles and oil-water contact angles, enabling literature data on air-water contact angles to be interpreted in terms of likely oil-water contact angles. In addition, we have found that while glass and silica surfaces modified by the same chemistry give the same contact angles in terms of air water contact angles, the surfaces are not as similar in terms of oil-water contact angles. These studies are being carried out in conjunction with immiscible displacements of water by liquid and supercritical CO2 in microfabricated pore network micromodels in silicon with oxidized silica surfaces and glass cover plates.

  2. Chemical projectile-target interaction and liquid immiscibility in impact glass from the Wabar craters, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Hamann, Christopher; Hecht, Lutz; Ebert, Matthias; Wirth, Richard

    2013-11-01

    Impact glasses are usually strongly affected by secondary alteration and chemical weathering. Thus, in order to understand relevant formation processes, detailed petrographic studies on unweathered impact glasses are necessary as preserved heterogeneities in quenched impact glasses may serve as a tool to better understand their genesis. Here, we report on petrography and microchemistry of impact glasses from the Wabar impact craters (Saudi Arabia) that, with an age of ∼300 years, are among the youngest terrestrial impact craters. The fact that parts of the IIIAB iron meteorite have survived impact and subsequent weathering is granting Wabar a special role among the presently 184 confirmed terrestrial impact structures. Electron microprobe analysis (EMPA) and transmission electron microscopy (TEM) obtained on the black impact melt/glass variety at Wabar suggest that meteoritic Fe was selectively mixed with high-silica target melt at high temperatures due to selective oxidation, resulting in high Fe/Ni ratios for the black melt (37 on average, individual values range from 13 to 449) and low Fe/Ni ratios for projectile droplets ("FeNi spheres" with a Fe/Ni ratio of 3 on average; Fe/Ni ratio for the meteorite is ∼12). The black melt shows emulsion textures that are the result of silicate liquid immiscibility. Liquid-liquid phase-separation resulted in the formation of a poorly polymerized, ultrabasic melt (Lfe) rich in divalent cations like Fe2+, Ca2+, or Mg2+, that is dispersed in a highly polymerized, high-silica melt (Lsi) matrix. The typical Wabar black melt emulsion displays a spheres-in-a-matrix texture of ∼10-20% Lfe homogeneously dispersed in the form of two sets of spheres and droplets (10-30 nm and 0.1-0.4 μm in diameter) in ∼80-90% Lsi matrix, plus occasionally disseminated FeNi spheres. Around large (>10 μm) FeNi spheres, however, the typical emulsion texture changes to ∼21% Lsi dispersed in ∼79% Lfe. This change of texture is interpreted as

  3. Progress and investigation on lattice Boltzmann modeling of multiple immiscible fluids or components with variable density and viscosity ratios

    SciTech Connect

    Leclaire, Sébastien Reggio, Marcelo; Trépanier, Jean-Yves

    2013-08-01

    Lattice Boltzmann models for simulating multiphase flows are relatively new, and much work remains to be done to demonstrate their ability to solve fundamental test cases before they are considered for engineering problems. From this perspective, a hydrodynamic lattice Boltzmann model for simulating immiscible multiphase flows with high density and high viscosity ratios, up to O(1000) and O(100) respectively, is presented and validated against analytical solutions. The method is based on a two phase flow model with operators extended to handle N immiscible fluids. The current approach is O(N) in computational complexity for the number of different gradient approximations. This is a major improvement, considering the O(N{sup 2}) complexity found in most works. A sequence of systematic and essential tests have been conducted to establish milestones that need to be met by the proposed approach (as well as by other methods). First, the method is validated qualitatively by demonstrating its ability to address the spinodal decomposition of immiscible fluids. Second, the model is quantitatively verified for the case of multilayered planar interfaces. Third, the multiphase Laplace law is studied for the case of three fluids. Fourth, a quality index is developed for the three-phase Laplace–Young’s law, which concerns the position of the interfaces between the fluids resulting from the different surface tensions. The current model is compatible with the analytical solution, and is shown to be first order accurate in terms of this quality index. Finally, the multilayered Couette’s flow is studied. In this study, numerical results can recover the analytical solutions for all the selected test cases, as long as unit density ratios are considered. For high density and high viscosity ratios, the analytical solution is recovered for all tests, except that of the multilayered Couette’s flow. Numerical results and a discussion are presented for this unsuccessful test case

  4. Enhanced-Solubilization of a Multi-Component Immiscible Liquid Source Zone within an Intermediate-scale Flow Cell System

    NASA Astrophysics Data System (ADS)

    Harvell, J. R.; Tick, G. R.

    2011-12-01

    Complex multi-component immiscible liquid mixtures can significantly limit the effectiveness of groundwater remediation. The use of enhanced-flushing technologies has emerged as a promising technique for the remediation of sites contaminated with immiscible liquids. A series of two dimensional (2-D) flow cell experiments was conducted to quantify the effectiveness of two different flushing agents on the removal of a uniformly distributed multi-component immiscible liquid source zone. A 39.5 x 20.2 cm flow-cell was packed with 20/30-mesh sand and emplaced with a 15 x 3 cm rectangular source zone within the center of the flow cell. The source zone was established with a 10% NAPL saturation (Sn) consisting of equal 1:1:1 mole mixture of tetrachloroethene (PCE), trichloroethene (TCE), and cis-1,2-dichloroethene (DCE). The solubilization agents investigated included 5 wt% solution of a complexing sugar, hydroxypropyl-$betacyclodextrin (HPCD), and a 5 wt% solution of a surfactant, sodium dodecyl sulfate (SDS). The results of these experiments indicate that the addition of a chemical flushing agent greatly reduces the time needed to remove each component compared to flushing with water alone (i.e. pump and treat). Elution curve (concentration-time) analysis from both total extraction and at the down-gradient end of the source zone showed that SDS removed all three components from the source zone approximately 10 times faster than HPCD. For the extraction port SDS showed slightly more ideal removal in terms of mass flux behavior, removing more mass initially before a significant reduction in mass flux was observed. Although SDS was superior when evaluated on a recovery basis, HPCD outperformed SDS for all components when compared based on contaminant-mass to reagent-mass and moles of contaminant to moles of reagent removed for the source zone port. These findings suggest that the selection of a particular flushing agent should be evaluated carefully prior to remediation as

  5. FIELD TEST OF CYCLODEXTRIN FOR ENHANCED IN-SITU FLUSHING OF MULTIPLE-COMPONENT IMMISCIBLE ORGANIC LIQUID CONTAMINATION: PROJECT OVERVIEW AND INITIAL RESULTS

    EPA Science Inventory

    The purpose of this paper is to present an overview and the initial results of a pilot-scale experiment designated to test the use of cyclodextrin for enhanced in-situ flushing of an aquifer contaminated by immiscible liquid. This is the first field test of this technology, terme...

  6. FIELD TEST OF CYCLODEXTRIN FOR ENHANCED IN-SITU FLUSHING OF MULTIPLE-COMPONENT IMMISCIBLE ORGANIC LIQUID CONTAMINATION: PROJECT OVERVIEW AND INITIAL RESULTS

    EPA Science Inventory

    The purpose of this paper is to present an overview and the initial results of a pilot-scale experiment designated to test the use of cyclodextrin for enhanced in-situ flushing of an aquifer contaminated by immiscible liquid. This is the first field test of this technology, terme...

  7. Exchange flows of two immiscible Newtonian liquids in a vertical tube: From falling drops to falling slugs

    NASA Astrophysics Data System (ADS)

    Varges, P. R.; Fonseca, B. S.; Naccache, M. F.; de Souza Mendes, P. R.

    2017-06-01

    We present an experimental study of buoyancy-driven flows of two immiscible Newtonian liquids in a vertical tube where initially the heavier and more viscous one is placed on the top of the lighter one. Flow visualization was performed using a digital camera, and inversion velocities were determined through image analysis. The influence of the governing parameters on the speed and flow regime was examined for pairs of liquids with small density differences. Two different flow regimes were observed, namely, falling drops and falling slugs. In the first regime, spherical and ellipsoidal drops are obtained, depending on the ratio between the drop and tube diameters. The falling slug regime is a core-annular flow pattern above a critical value of interfacial tension, while no flow is noticed below this critical value. The experimental results are in good agreement with model predictions from the literature. Indeed, the results showed that terminal velocity can be estimated by empirical correlations for falling spheres.

  8. Microconfined shear deformation of a droplet in an equiviscous non-newtonian immiscible fluid: experiments and modeling.

    PubMed

    Minale, Mario; Caserta, Sergio; Guido, Stefano

    2010-01-05

    In this work, the microconfined shear deformation of a droplet in an equiviscous non-Newtonian immiscible fluid is investigated by modeling and experiments. A phenomenological model based on the assumption of ellipsoidal shape and taking into account wall effects is proposed for systems made of non-Newtonian second-order fluids. The model, without any adjustable parameters, is tested by comparison with experiments under simple shear flow performed in a sliding plate apparatus, where the ratio between the distance between the confining walls and the droplet radius can be varied. The agreement between model predictions and experimental data is good both in steady state shear and in transient drop retraction upon cessation of flow. The results obtained in this work are relevant for microfluidics applications where non-Newtonian fluids are used.

  9. Apparatus and method for pumping hot, erosive slurry of coal solids in coal derived, water immiscible liquid

    DOEpatents

    Ackerman, Carl D.

    1983-03-29

    An apparatus for and method of pumping hot, erosive slurry of coal solids in a coal derived, water immiscible liquid to higher pressure involves the use of a motive fluid which is miscible with the liquid of the slurry. The apparatus includes a pump 12, a remote check valve 14 and a chamber 16 between and in fluid communication with the pump 12 and check valve 14 through conduits 18,20. Pump 12 exerts pressure on the motive fluid and thereby on the slurry through a concentration gradient of coal solids within chamber 16 to alternately discharge slurry under pressure from the outlet port of check valve 14 and draw slurry in through the inlet port of check valve 14.

  10. Surfactant chain length and concentration influence on the interfacial tension of two immiscible model liquids: a coarse-grained approach.

    PubMed

    Catarino Centeno, R; Bustamante-Rendón, R A; Hernández-Fragoso, J S; Arroyo-Ordoñez, I; Pérez, E; Alas, S J; Gama Goicochea, A

    2017-10-06

    The interfacial tension between immiscible liquids is studied as a function of a model linear surfactant length and concentration using coarse-grained, dissipative particle dynamics numerical simulations. The adsorption isotherms obtained from the simulations are found to be in agreement with Langmuir's model. The reduction of the interfacial tension with increasing surfactant concentration is found to display some common characteristics for all the values of chain length modeled, with our predictions being in agreement with Szyszkowski's equation. Lastly, the critical micelle concentration is predicted for all surfactant lengths, finding exponentially decaying behavior, in agreement with Kleven's model. It is argued that these findings can be helpful guiding tools in the interpretation of available experiments and in the design of new ones with new surfactants and polymers.

  11. Specific interface area in a thin layer system of two immiscible liquids with vapour generation at the contact interface

    NASA Astrophysics Data System (ADS)

    Pimenova, Anastasiya V.; Gazdaliev, Ilias M.; Goldobin, Denis S.

    2017-06-01

    For well-stirred multiphase fluid systems the mean interface area per unit volume, or “specific interface area” SV, is a significant characteristic of the system state. In particular, it is important for the dynamics of systems of immiscible liquids experiencing interfacial boiling. We estimate the value of parameter SV as a function of the heat influx {\\dot{Q}}V to the system or the average system overheat <Θ> above the interfacial boiling point. The derived results can be reformulated for the case of an endothermic chemical reaction between two liquid reagents with the gaseous form of one of the reaction products. The final results are restricted to the case of thin layers, where the potential gravitational energy of bubbles leaving the contact interface is small compared to their surface tension energy.

  12. Spin-dipole oscillation and polarizability of a binary Bose-Einstein condensate near the miscible-immiscible phase transition

    NASA Astrophysics Data System (ADS)

    Bienaimé, Tom; Fava, Eleonora; Colzi, Giacomo; Mordini, Carmelo; Serafini, Simone; Qu, Chunlei; Stringari, Sandro; Lamporesi, Giacomo; Ferrari, Gabriele

    2016-12-01

    We report on the measurement of the spin-dipole (SD) polarizability and of the frequency of the SD oscillation of a two-component Bose-Einstein condensate of sodium atoms occupying the |3 2S1 /2,F =1 ,mF=±1 > hyperfine states. This binary spin mixture presents the important properties of being, at the same time, fully miscible and rid of the limit set by buoyancy. It is also characterized by a huge enhancement of the SD polarizability and by the consequent softening of the frequency of the SD oscillation, due to the vicinity to the transition to the immiscible phase. The experimental data are successfully compared with the predictions of theory.

  13. Three-dimensional simulations of pressure-driven displacement flow of two immiscible liquids using a multiphase Lattice Boltzmann approach

    NASA Astrophysics Data System (ADS)

    Redapangu, Prasanna R.; Sahu, Kirti Chandra; Vanka, S. P.

    2013-11-01

    A three-dimensional multiphase lattice Boltzmann approach is used to study the pressure-driven displacement flow of two immiscible liquids of different densities and viscosities in an inclined square duct. A three-dimensional-fifteen-velocity (D3Q15) lattice model is used. The simulations are performed on a graphics processing unit (GPU) based machine. The effects of channel inclination, viscosity and density contrasts are investigated. The contours of the density and the average viscosity profiles in different planes are plotted and compared with two dimensional simulations. We demonstrate that the flow dynamics in three-dimensional channel is quite different as compared to that of two-dimensional channel. In particular, we found that the flow is relatively more coherent in three-dimensional channel than that in two-dimensional channel. A new screw-type instability is seen in the three-dimensional channel which cannot be observed in two-dimensional simulations.

  14. Effect of Various Enhanced-Solubilization Agents on Multi-Component Immiscible Liquid Dissolution and Mass Flux in Homogeneous Porous Media

    NASA Astrophysics Data System (ADS)

    Tick, G. R.; Slavic, D.

    2010-12-01

    Complex multi-component immiscible liquid mixtures can significantly limit the effectiveness of groundwater remediation. The use of enhanced-flushing technologies has emerged as a promising technique for the remediation of sites contaminated with immiscible liquids. An important aspect for the effective remediation of these sites depends on the physical heterogeneity of the subsurface, the related distribution of immiscible liquid present within porous media, and the composition of the immiscible liquid mixture. A series of column experiments was conducted to quantify the effectiveness of four different flushing agents on the removal of a uniformly distributed multi-component immiscible liquid consisting of equal mole fractions of tetrachloroethene (PCE), trichloroethene (TCE), and cis-1,2-dichloroethene (DCE) in homogeneous quartz sand. The solubilization agents investigated included: two complexing sugars, hydroxypropyl-β-cyclodextrin (HPCD) and methyl-β-cyclodextrin (MCD); one surfactant, sodium dodecyl sulfate (SDS); and one cosolvent, ethanol (ETOH). The effectiveness of the flushing agents was evaluated by comparing elution profiles, flushing efficiencies, mass flux behavior, and dissolution ideality (i.e. Raoult’s law prediction) of each component. The results of these experiments indicate that the addition of a chemical flushing agent greatly reduces the time needed to remove each component compared to flushing with water alone (i.e. pump and treat). Although the stronger solubilization-power agents (i.e. SDS and ETOH) showed quicker removal in general, each solubilization agent exhibited unique removal limitations based upon different removal efficiency analyses. For instance, TCE and DCE exhibited relatively ideal dissolution while PCE showed significant nonideal dissolution behavior during flushing with MCD. These findings suggest that the selection of a particular flushing agent should be evaluated carefully prior to remediation as the mass flux and

  15. Development of an immiscible polymer/polymer/nanoparticle system in order to study the location of nanoparticles at polymer/polymer interface by quantitative optical microscopy

    NASA Astrophysics Data System (ADS)

    Johansen, Luis Henrique B.; Canto, Leonardo B.; Canevarolo, Sebastião V.

    2015-12-01

    In the past ten years, stabilization of the phase morphology of immiscible polymer blends during melt compounding went through a new perspective by the use of inorganic nanoparticles as compatibilizers. Following the ideas of Ramsden and Pickering, the stabilization of the minor phase in immiscible polymer blends could be achieved with solid nanoparticles located at the interface of the phases, lowering the interfacial tension and acting as a physical barrier to droplet coalescence. In this work, the location of the silica nanoparticle in an immiscible polymer blend is studied using quantitative optical microscopy, measuring the total light scattering, i.e. turbidity, created by the use of hydrophilic and hydrophobic silica nanoparticles (hi-silica and hb-silica, respectively) in an immiscible polymer blend. The light scattering at the polymer/polymer interface is minimized choosing a PS/PC immiscible blend which has minimal difference in their refractive indices. On the other hand, the considerable difference in the refractive index of the chosen polymers and nanosilica would highlight the scattering effect of the silica nanoparticles if located at the polymer/polymer interface. The transmitted light intensity from neat PS/PC blends and some PS/PC/hl-silica systems were similar, showing only a small change in the range of the glass transition temperatures of the two polymers, which is an indication that the silica nanoparticles are dispersed inside the two polymer phases. However, the transmitted light intensity is greatly changed in the system PS/PC/hb-silica, containing the hydrophobic silica, which according to the wetting parameter should have the silica nanoparticles located mainly at the polymer/polymer interface.

  16. Mass Transfer in the Dissolution of a Multi-Component Liquid Droplet in an Immiscible Liquid Environment

    PubMed Central

    Su, Jonathan T.; Needham, David

    2013-01-01

    The Epstein Plesset equation has recently been shown to accurately predict the dissolution of a pure liquid microdroplet into a second immiscible solvent, such as oil into water. Here, we present a series of new experiments and a modification to this equation to model the dissolution of a two-component oil-mixture microdroplet into a second immiscible solvent, in which the two materials of the droplet have different solubilities. The model is based upon a reduced surface area approximation and the assumption of ideal homogenous mixing: Massfluxdmidt=AfraciDi(ci-cs){1R+1πDit}, where Afraci is the area fraction of component I; ci and cs are the initial and saturation concentrations of the droplet material in the surrounding medium; R is the radius of the droplet; t is time; and Di is the coefficient of diffusion of component I in the surrounding medium. This new model has been tested by use of a two-chamber micropipette-based method, which measured the dissolution of single individual microdroplets of mutually-miscible liquid mixtures (ethyl acetate/butyl acetate, and butyl acetate/amyl acetate) into water. We additionally measured the diffusion coefficient of the pure materials: ethyl acetate, butyl acetate, and amyl acetate, in water at 22 deg C. Diffusion coefficients for the pure acetates in water were: 8.65 x 10−6, 7.61 x 10−6, and 9.14 x 10−6 cm2/s respectively. This model accurately predicts the dissolution of microdroplets for the ethyl acetate/butyl acetate and butyl acetate/amyl acetate systems given the solubility and diffusion coefficients of each of the individual components in water as well as the initial droplet radius. The average mean squared error was 8.96%. The dissolution of a spherical ideally mixed multi-component droplet closely follows the modified Epstein Plesset model presented here. PMID:24050124

  17. Carbonate-silicate immiscibility and extremely peralkaline silicate glasses from Nasira cone and recent eruptions at Oldoinyo Lengai Volcano, Tanzania

    NASA Astrophysics Data System (ADS)

    Mitchell, Roger H.; Dawson, J. Barry

    2012-11-01

    Phenocrysts of garnet, pyroxene and nepheline in peralkaline nephelinite from the Nasira parasitic cones at Oldoinyo Lengai contain quenched immiscible silicate (peralkalinity = 2-13) and Na-Ca-carbonate melts. Their bulk compositions further define the limits of liquid immiscibility for peralkaline carbonated nephelinite magmas and confirm this process was operative at Oldoinyo Lengai during older stages of activity. Groundmass glasses in Nasira nephelinites are peralkaline (peralkalinity = 5.5-9.5) but less evolved than melt inclusion glasses (peralkalinity = 8-13) in nepheline phenocrysts, implying that these magmas are hybrids formed by magma mixing. Groundmass glass in diverse peralkaline combeite nephelinite ash clasts with and without melilite and/or wollastonite formed in the January-June 2008 eruptions of Oldoinyo Lengai are also exceptionally peralkaline. Two trends in their compositions are evident: (1) increasing peralkalinity from 6 to 10 with SiO2 decreasing from 42 to 33 wt.%; (2) increasing peralkalinity from 6 to 16 with SiO2 decreasing from 45 to 40 wt.%. All recent glasses are considered to be more evolved than groundmass glass in Nasira combeite nephelinite. These data indicate that several varieties of nephelinite exist at Oldoinyo Lengai. Their parental magmas are considered to have been initially enriched in alkalis during partial melting of their metasomatized asthenospheric sources and further by subsequent assimilation, or re-solution, of previously exsolved natrocarbonatite melt in the magma chamber(s) underlying Oldoinyo Lengai. On this basis, none of the bulk compositions of peralkaline stage II lavas at Oldoinyo Lengai, including Nasira, are considered to represent those of liquids as their compositions are determined by rheological factors (phenocryst accumulation; cumulate disruption) and assimilation processes. The formation of combeite is considered to be a consequence of natrocarbonatite melt assimilation.

  18. Pore-scale Evaluation of Immiscible Fluid Characteristics and Displacements: Comparison Between Ambient- and Supercritical-Condition Experimental Studies

    NASA Astrophysics Data System (ADS)

    Herring, A. L.; Wildenschild, D.; Andersson, L.; Harper, E.; Sheppard, A.

    2015-12-01

    The transport of immiscible fluids within porous media is a topic of great importance for a wide range of subsurface processes; e.g. oil recovery, geologic sequestration of CO2, gas-water mass transfer in the vadose zone, and remediation of non-aqueous phase liquids (NAPLs) from groundwater. In particular, the trapping and mobilization of nonwetting phase fluids (e.g. oil, CO2, gas, or NAPL in water-wet media) is of significant concern; and has been well documented to be a function of both wetting and nonwetting fluid properties, morphological characteristics of the porous medium, and system history. However, generalization of empirical trends and results for application between different fluid-fluid-medium systems requires careful consideration and characterization of the relevant system properties. We present a comprehensive and cohesive description of nonwetting phase behaviour as observed via a suite of three dimensional x-ray microtomography imaging experiments investigating immiscible fluid flow, trapping, and interfacial interactions of wetting (brine) and nonwetting (air, oil, and supercritical CO2) phase in sandstones and synthetic media. Microtomographic images, acquired for drainage and imbibition flow processes, allow for precise and extensive characterization of nonwetting phase fluid saturation, topology, and connectivity; imaging results are paired with externally measured capillary pressure data to provide a comprehensive description of fluid states. Fluid flow and nonwetting phase trapping behaviour is investigated as a function of system history, morphological metrics of the geologic media, and nonwetting phase fluid characteristics; and particular emphasis is devoted to the differences between ambient condition (air-brine) and reservoir condition (supercritical CO2-brine) studies. Preliminary results provide insight into the applicability of using ambient condition experiments to explore reservoir condition processes, and also elucidate the

  19. In situ stabilization of entrapped elemental mercury.

    PubMed

    Devasena, M; Nambi, Indumathi M

    2013-11-30

    Elemental mercury is a dense immiscible fluid which gets entrapped as residual mercury in the pore spaces of the subsurface during improper disposals and accidental spills. This paper investigates in situ stabilization of entrapped elemental mercury to mercury sulphide using aqueous sodium polysulphide solution. Batch experiments showed 100% conversion efficiency of elemental mercury to mercury sulphide in a period of 96 h with sodium polysulphide/elemental mercury molar ratio of 1. XRD analysis identified the precipitate formed as mercury sulphide. Micromodel experiments, with glass beads as porous media, further demonstrated in situ stabilization of entrapped mercury under different residual mercury saturations. It was found that in a period of 10 days, 10% of entrapped mercury was stabilized as mercury sulphide, 0.088% was removed as dissolved mercury and the remaining elemental mercury was retained in porous media encapsulated by the newly formed mercury sulphide precipitate. However, there was no leaching of mercury from the micromodel effluent once stabilization was achieved. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Large-scale liquid immiscibility and fractional crystallization in the 1780 Ma Taihang dyke swarm: Implications for genesis of the bimodal Xiong'er volcanic province

    NASA Astrophysics Data System (ADS)

    Peng, Peng; Wang, Xinping; Lai, Yong; Wang, Chong; Windley, Brian F.

    2015-11-01

    Immiscibility is a potential mechanism for the formation of high-Fe-Ti-P rocks; however, whether large-scale segregation and eruption of high-Si lavas can occur in nature has yet to be proven. In this study, we investigate the possibility of immiscibility between the cogenetic 1780 Ma high-Fe-Ti-P-bearing Taihang dykes and the 'bimodal' Xiong'er volcanics in North China. The compositions of silicate melt inclusions in plagioclase megacrysts of the dykes provide a new approach to obtain the primary liquid. Mineral and bulk-rock compositions reveal that large compositional variations in the dykes are the result of plagioclase- and clinopyroxene-dominated fractional crystallization and of density-driven mineral sorting, which together caused the liquids to be poor in Ca-Al but rich in Fe-Ti-P-K, and thus chemically immiscible. Conjugate interstitial granophyric and ilmenite-rich intergrowths and reactive microstructures especially olivine coronas in the dykes, and Si-/Fe-Ti-rich globules in the volcanics, provide petrographic evidence for the presence of two coeval, coexisting liquids in equilibrium separated by a miscibility gap, and thus for immiscibility and segregation/migration. The fractional crystallization and subsequent segregation were responsible for the compositional diversity of the Taihang dykes and also of the 'bimodal' Xiong'er volcanics. Accordingly, the dacite and rhyolite lavas are potentially the high-Si counterparts of the high-Ti dykes, and the basalt and andesite lavas are the erupted equivalents of the relatively low-Ti dykes. It is likely that the sustained plagioclase- and clinopyroxene-dominated fractional crystallization, and the enhanced fO2 were responsible for the immiscibility. The segregation probably took place during the ascent of the liquid in the pumping system (feeder dykes). This likely represents one natural example of crust-scale immiscibility from which many high-Ti dykes and silicic lavas (~ 1/3 volume of the Xiong

  1. Self-organization of Cu-based immiscible alloys under irradiation: An atom-probe tomography study

    NASA Astrophysics Data System (ADS)

    Stumphy, Brad D.

    The stability of materials subjected to prolonged irradiation has been a topic of renewed interest in recent years due to the projected growth of nuclear power as an alternative energy source. The irradiating particles impart energy into the material, thereby causing atomic displacements to occur. These displacements result in the creation of point defects and the random ballistic mixing of the atoms. Consequently, the material is driven away from its equilibrium structure. The supersaturation of defects can lead to the degradation of mechanical properties, but a high density of internal interfaces, which act as defect sinks, will suppress the supersaturation and long-range transport of defects. The microstructural evolution of the material is controlled by the ballistic mixing as well as the mobility of the point defects. In immiscible alloys, these two processes compete against one another, as the ballistic mixing acts to solutionize the alloy components, and the thermal diffusion of the large number of defects acts to phase separate the components. The work presented in this dissertation examines the effect of heavy-ion irradiation on immiscible, binary Cu-based alloys. Dilute alloys of Cu-Fe, Cu-V, and V-Cu have been subjected to irradiation, and atom-probe tomography has been utilized in order to better understand the complex nature of the response of these simple model systems to an irradiation environment. The results show that a steady-state, nano-scale patterning structure, with a high density of unsaturable defect sinks, can be maintained under prolonged irradiation. Additionally, precipitation from a supersaturated solid solution is shown to be a function of both the thermal diffusion and the ballistic mixing. Solvent-rich secondary precipitates, termed "cherry-pits," are observed inside of the solute-rich primary precipitates. Through a combination of simulation work and analyzing multiple alloys experimentally, it was determined that this cherry

  2. Crustal contamination and sulfide immiscibility history of the Permian Huangshannan magmatic Ni-Cu sulfide deposit, East Tianshan, NW China

    NASA Astrophysics Data System (ADS)

    Mao, Ya-Jing; Qin, Ke-Zhang; Tang, Dong-Mei; Feng, Hong-Ye; Xue, Sheng-Chao

    2016-11-01

    The Huangshannan mafic-ultramafic intrusion is a Permian Ni-Cu sulfide-bearing intrusion in the southern margin of the Central Asian Orogenic Belt. The intrusion consists of an ultramafic unit, which is composed of lherzolite and olivine websterite, and a mafic unit, which is composed of olivine gabbronorite, gabbronorite and leuco-gabbronorite. This intrusion was formed by two separate pulses of magma: a more primitive magma for the early ultramafic unit and a more evolved magma for the late mafic unit. U-Pb isotope geochronology of zircon from the mafic unit yields an age of 278 ± 2 Ma. According to its olivine and Cr-rich spinel compositions, the estimated parental magma of lherzolite for the Huangshannan intrusion has 12.4 wt.% MgO, indicating picritic affinity. Fractional crystallization modeling results and the presence of rounded sulfide inclusions in an olivine crystal (Fo 86.7) indicate that sulfide immiscibility was achieved at the beginning of olivine fractionation. Co-magmatic zircon crystals from gabbronorite have a δ18O value close to 6.5‰, which is 1.2‰ higher than the typical mantle value and suggests significant crustal contamination (∼20%). The positive εHf(t) values of co-magmatic zircon (which vary from +9.2 to +15.3) and positive whole rock εNd(t) values (which vary from +4.7 to +7.8) also indicate that the parental magma was derived from a depleted mantle source and contaminated by 5-20% juvenile arc crust and then by ∼5% upper crustal materials. However, modeling results of sulfur content at sulfide saturation reveal that such a large amount of crustal contamination is not sufficient to trigger sulfide saturation in the parental magma, which strongly suggests that external sulfur addition, probably during contamination, has played a critical role in causing sulfide immiscibility. Furthermore, the arc magmatism geochemical signatures of the Huangshannan intrusion, such as significant Nb and Ta depletion relative to La and low Ca

  3. Immiscible silicate liquids and phosphoran olivine in Netschaëvo IIE silicate: Analogue for planetesimal core-mantle boundaries

    NASA Astrophysics Data System (ADS)

    Van Roosbroek, Nadia; Hamann, Christopher; McKibbin, Seann; Greshake, Ansgar; Wirth, Richard; Pittarello, Lidia; Hecht, Lutz; Claeys, Philippe; Debaille, Vinciane

    2017-01-01

    We have investigated a piece of the Netschaëvo IIE iron meteorite containing a silicate inclusion by means of electron microprobe analysis (EMPA) and transmission electron microscopy (TEM). Netschaëvo contains chondrule-bearing clasts and impact melt rock clasts were also recently found. The examined inclusion belongs to the latter and is characterized by a porphyritic texture dominated by clusters of coarse-grained olivine and pyroxene, set in a fine-grained groundmass that consists of new crystals of olivine and a hyaline matrix. This matrix material has a quasi-basaltic composition in the inner part of the inclusion, whereas the edge of the inclusion has a lower SiO2 concentration and is enriched in MgO, P2O5, CaO, and FeO. Close to the metal host, the inclusion also contains euhedral Mg-chromite crystals and small (<2 μm), Si-rich globules. A TEM foil was cut from this glassy, silico-phosphate material. It shows that the material consists of elongated olivine crystallites containing up to 14 wt% P2O5, amorphous material, and interstitial Cl-apatite crystals. The Si-rich silicate glass globules show a second population of Fe-rich silicate glass droplets, indicating they formed by silicate liquid immiscibility. Together with the presence of phosphoran olivine and quenched Cl-apatite, these textures suggest rapid cooling and quenching as a consequence of an impact event. Moreover, the enrichment of phosphorus in the silicate inclusion close to the metal host (phosphoran olivine and Cl-apatite) indicates that phosphorus re-partitioned from the metal into the silicate phase upon cooling. This probably also took place in pallasite meteorites that contain late-crystallizing phases rich in phosphorus. Accordingly, our findings suggest that oxidation of phosphorus might be a general process in core-mantle environments, bearing on our understanding of planetesimal evolution. Thus, the Netschaëvo sample serves as a natural planetesimal core-mantle boundary experiment

  4. Substrats poreux biodegradables prepares a partir de phases co-continues dans les melanges de polymeres immiscibles

    NASA Astrophysics Data System (ADS)

    Sarazin, Pierre

    2003-06-01

    In this thesis a novel approach to preparing biodegradable materials with highly structured and interconnected porosity is proposed. The method involves the controlled preparation of immiscible co-continuous polymer blends using melt-processing technology followed by a bulk solvent extraction step of one of the phases (the porogen phase). A co-continuous structure is defined as the state when each phase of the blend is fully interconnected through a continuous pathway. This method allows for the preparation of porous materials with highly controlled pore size, pore volume and pore shape which can then be transformed and shaped in various forms useful for biomedical applications. Various properties of the skin of the polymeric articles (closed-cell, open-cell, modification of the pore size) can be controlled. Initially, the study on the immiscible binary and compatibilized poly(L-lactide)/polystyrene blends (PLLA/PS) after extraction of the PS phase demonstrated that highly percolated blends exist from 40--75%PS and 40--60%PS for the binary and compatibilized blends, respectively. It is demonstrated that both the pore size and extent of co-continuity can be controlled through composition and interfacial modification. The subsequent part of our work treats of the preparation of porous PLLA from a blend of two biodegradable polymers and the performance of such porous materials. This portion of the work uses only polymer materials which have been medically approved for internal use. In this case, small amounts of the porogen phase can be tolerated in the final porous substrate. Co-continuous blends comprised of poly(L-lactide)/Poly(epsilon-caprolactone) PLLA/PCL, were prepared via melt processing. A wide range of phase sizes for the co-continuous blend is generated through a combination of concentration control and quiescent annealing. As the PLLA phase can not be dissolved selectively in PLLA/PS blends, the co-continuity range was evaluated indirectly. To precisely

  5. Using Three-Phase Flow of Immiscible Liquids to Prevent Coalescence of Droplets in Microfluidic Channels: Criteria to Identify theThird Liquid and Validation with Protein Crystallizations

    SciTech Connect

    Chen, D.; Li, L; Reyes, S; Adamson, D; Ismagilov, R

    2007-01-01

    This manuscript describes the effect of interfacial tensions on three-phase liquid-liquid-liquid flow in microfluidic channels and the use of this flow to prevent microfluidic plugs from coalescing. One problem in using microfluidic plugs as microreactors is the coalescence of adjacent plugs caused by the relative motion of plugs during flow. Here, coalescence of reagent plugs was eliminated by using plugs of a third immiscible liquid as spacers to separate adjacent reagent plugs. This work tested the requirements of interfacial tensions for plugs of a third liquid to be effective spacers. Two candidates satisfying the requirements were identified, and one of these liquids was used in the crystallization of protein human Tdp1 to demonstrate its compatibility with protein crystallization in plugs. This method for identifying immiscible liquids for use as a spacer will also be useful for applications involving manipulation of large arrays of droplets in microfluidic channels.

  6. A novel numerical approach for the solution of the problem of two-phase, immiscible flow in porous media: Application to LNAPL and DNAPL

    NASA Astrophysics Data System (ADS)

    Salama, Amgad; Sun, Shuyu; El Amin, Mohamed F.

    2012-05-01

    The flow of two immiscible fluids in porous media is ubiquitous particularly in petroleum exploration and extraction. The displacement of one fluid by another immiscible with it represents a very important aspect in what is called enhanced oil recovery. Another example is related to the long-term sequestration of carbon dioxide, CO2, in deep geologic formations. In this technique, supercritical CO2 is introduced into deep saline aquifer where it displaces the hosting fluid. Furthermore, very important classes of contaminants that are very slightly soluble in water and represent a huge concern if they get introduced to groundwater could basically be assumed immiscible. These are called light non-aqueous phase liquids (LNAPL) and dense non-aqueous phase liquids (DNAPL). All these applications necessitate that efficient algorithms be developed for the numerical solution of these problems. In this work we introduce the use of shifting matrices to numerically solving the problem of two-phase immiscible flows in the subsurface. We implement the cell-center finite difference method which discretizes the governing set of partial differential equations in conservative manner. Unlike traditional solution methodologies, which are based on performing the discretization on a generic cell and solve for all the cells within a loop, in this technique, the cell center information for all the cells are obtained all at once without loops using matrix oriented operations. This technique is significantly faster than the traditional looping algorithms, particularly for larger systems when coding using languages that require repeating interpretation each time a loop is called like Mat Lab, Python and the like. We apply this technique to the transport of LNAPL and DNAPL into a rectangular domain.

  7. Two-phase amorphous-amorphous solid drug dispersion with enhanced stability, solubility and bioavailability resulting from ultrasonic dispersion of an immiscible system.

    PubMed

    Martínez, Luz María; Videa, Marcelo; López Silva, Tania; Castro, Samuel; Caballero, Adolfo; Lara-Díaz, Víctor J; Castorena-Torres, Fabiola

    2017-10-01

    Amorphization of active pharmaceutical ingredients (APIs) and the preparation of solid dispersions are strategies that can be synergized to improve the solubility of oral drugs. Immiscibility between an API and a carrier in the molten state that could be perceived as a problem in the preparation of solid dispersions, may actually introduce an advantage. In the present work, a two-phase amorphous-amorphous solid dispersion (AASD) was prepared by ultrasonicating a molten immiscible mixture of indomethacin (IND) and glucose (GLU) prior quenching. By introducing this novel ultrasound assisted method, the immiscible API particles were uniformly dispersed as microscopic glassy clusters of the drug in the solid amorphous GLU matrix; particle sizes of IND in the AASD range from 600nm to 1.4μm. As a result of the amorphization and particle size reduction of IND, its aqueous solubility increased to reach almost 40ppm (8 times more soluble compared to indomethacin in its crystalline state). In addition, the oral bioavailability and its resistance against crystallization were also enhanced; AASD samples have remained amorphous for more than two years of storage. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Elemental ZOO

    NASA Astrophysics Data System (ADS)

    Helser, Terry L.

    2003-04-01

    This puzzle uses the symbols of 39 elements to spell the names of 25 animals found in zoos. Underlined spaces and the names of the elements serve as clues. To solve the puzzle, students must find the symbols that correspond to the elemental names and rearrange them into the animals' names.

  9. Synthesis of 3D nanostructured metal alloy of immiscible materials induced by megahertz-repetition femtosecond laser pulses

    PubMed Central

    2012-01-01

    In this work, we have proposed a concept for the generation of three-dimensional (3D) nanostructured metal alloys of immiscible materials induced by megahertz-frequency ultrafast laser pulses. A mixture of two microparticle materials (aluminum and nickel oxide) and nickel oxide microparticles coated onto an aluminum foil have been used in this study. After laser irradiation, three different types of nanostructure composites have been observed: aluminum embedded in nickel nuclei, agglomerated chain of aluminum and nickel nanoparticles, and finally, aluminum nanoparticles grown on nickel microparticles. In comparison with current nanofabrication methods which are used only for one-dimensional nanofabrication, this technique enables us to fabricate 3D nanostructured metal alloys of two or more nanoparticle materials with varied composite concentrations under various predetermined conditions. This technique can lead to promising solutions for the fabrication of 3D nanostructured metal alloys in applications such as fuel-cell energy generation and development of custom-designed, functionally graded biomaterials and biocomposites. PMID:22999219

  10. 3D tomographic reconstruction of the internal velocity field of an immiscible drop in a shear flow

    NASA Astrophysics Data System (ADS)

    Kerdraon, Paul; Dalziel, Stuart B.; Goldstein, Raymond E.; Landel, Julien R.; Peaudecerf, Francois J.

    2015-11-01

    We study experimentally the internal flow of a drop attached to a flat substrate and immersed in an immiscible shear flow. Transport inside the drop can play a crucial role in cleaning applications. Internal advection can enhance the mass transfer across the drop surface, thus increasing the cleaning rate. We used microlitre water-glycerol drops on a hydrophobic substrate. The drops were spherical and did not deform significantly under the shear flow. An oil phase of relative viscosity 0.01 to 1 was flowed over the drop. Typical Reynolds numbers inside the drops were of the order of 0.1 to 10. Using confocal microscopy, we performed 3D tomographic reconstruction of the flow field in the drop. The in-plane velocity field was measured using micro-PIV, and the third velocity component was computed from incompressibility. To our knowledge, this study gives the first experimental measurement of the three-dimensional internal velocity field of a drop in a shear flow. Numerical simulations and theoretical models published in the past 30 years predict a toroidal internal recirculation flow, for which the entire surface flows streamwise. However, our measurements reveal a qualitatively different picture with a two-lobed recirculation, featuring two stagnation points at the surface and a reverse surface flow closer to the substrate. This finding appears to be independent of Reynolds number and viscosity ratio in the ranges studied; we conjecture that the observed flow is due to the effect of surfactants at the drop surface.

  11. Dynamic three-phase hollow fiber microextraction based on two immiscible organic solvents with automated movement of the acceptor phase.

    PubMed

    Esrafili, Ali; Yamini, Yadollah; Ghambarian, Mahnaz; Moradi, Morteza

    2011-01-01

    Dynamic three-phase hollow fiber liquid-liquid-liquid microextraction (HF-LLLME) based on two immiscible organic solvents, with automated movement of organic acceptor phase to facilitate mass transfer was introduced for the first time. Polycyclic aromatic hydrocarbons were used as model compounds and extracted from water and soil samples. The extraction involved filling an 8 cm length of hollow fiber with 25 μL of organic acceptor solvent using a microsyringe, followed by impregnation of the pores in the fiber wall with n-dodecane. The fiber was then immersed in 20 mL of aqueous sample solution. During extraction, the organic acceptor phase was repeatedly moved in the lumen of the hollow fiber by movement of the syringe plunger controlled by programmable syringe pump. Following this microextraction, 2 μL of organic acceptor phase was injected into gas chromatography-flame ionization detector. This new technique provided up to 554-fold preconcentration of the analytes under the optimized conditions. Good repeatabilities (with RSDs ≤8.4%) were obtained. Detection limits were in the range of 0.2-0.5 μg/L. The utilization of the proposed method for extraction of the polycyclic aromatic hydrocarbons from different real samples (such as water and soil samples) also gave good precision and recovery.

  12. Immiscible displacement of oil by water in consolidated porous media due to capillary imbibition under ultrasonic waves.

    PubMed

    Hamida, Tarek; Babadagli, Tayfun

    2007-09-01

    Numerous studies done in the last four decades have demonstrated that acoustic stimulation may enhance recovery in oil reservoirs. This technology is not only technically feasible, but also serves as an economical, environmentally friendly alternative to currently accepted enhanced oil recovery (EOR) method. It requires low capital expenditure, and yields almost immediate improvement without any additional EOR agents. Despite a vast body of empirical and theoretical support, this method lacks sufficient understanding to make meaningful and consistent engineering predictions. This is in part due to the complex nature of the physical processes involved, as well as due to a shortage of fundamental/experimental research. Much of what the authors believe is happening within acoustically stimulated porous media is speculative and theoretical. This paper focuses on the effects of ultrasound on the interfacial forces between immiscible fluids. Capillary (spontaneous) imbibition of an aqueous phase into oil (or air)-saturated Berea sandstone and Indiana limestone samples experiments were conducted. Solutions of water, brine (15,000 and 150,000 ppm NaCl), anionic surfactant (sodium dodecyl diphenyloxide disulfonate), nonionic surfactant (alcohol ethoxylate) and polymer (xanthan gum) were prepared as the aqueous phase. Both counter-current and co-current geometries were tested. Due to the intrinsically unforced, gentle nature of the process, and their strong dependence on wettability, interfacial tension, viscosity and density, such experiments provide valuable insight into some of the governing mechanisms behind ultrasonic stimulation.

  13. Electrically Controllable Microparticle Synthesis and Digital Microfluidic Manipulation by Electric-Field-Induced Droplet Dispensing into Immiscible Fluids

    NASA Astrophysics Data System (ADS)

    Um, Taewoong; Hong, Jiwoo; Kang, In Seok

    2016-11-01

    The dispensing of tiny droplets is a basic and crucial process in a myriad of applications, such as DNA/protein microarray, cell cultures, chemical synthesis of microparticles, and digital microfluidics. This work demonstrates the droplet dispensing into immiscible fluids through electric charge concentration (ECC) method. Three main modes (i.e., attaching, uniform and bursting modes) are exhibited as a function of flow rates, applied voltage and gap distance between the nozzle and the oil surface. Through a conventional nozzle with diameter of a few millimeters, charged droplets with volumes ranging from a few μL to a few tens of nL can be uniformly dispensed into the oil chamber without reduction in nozzle size. Based on the features of the proposed method (e.g., formation of droplets with controllable polarity and amount of electric charge in water and oil system), a simple and straightforward method is developed for microparticle synthesis, including preparation for colloidosomes and fabrication of Janus microparticles with anisotropic internal structures. Finally, a combined system consisting of ECC-induced droplet dispensing and electrophoresis of charged droplet (ECD)-driven manipulation systems is constructed. This work was supported by the BK21Plus Program for advanced education of creative chemical engineers of the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP).

  14. Sol-Gel synthesis of MgO-SiO2 glass compositions having stable liquid-liquid immiscibility

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1987-01-01

    MgO-SiO2 glasses containing up to 15 mol % MgO, which could not have been prepared by the conventional glass melting method due to the presence of stable liquid-liquid immiscibility, were synthesized by the sol-gel technique. Clear and transparent gels were obtained from the hydrolysis and polycondensation of silicon tetraethoxide (TEOS) and magnesium nitrate hexahydrate when the water/TEOS mole ratio was four or more. The gelling time decreased with increase in magnesium content, water/TEOS ratio, and reaction temperature. Magnesium nitrate hexahydrate crystallized out of the gels containing 15 and 20 mol % MgO on slow drying. This problem was partially alleviated by drying the gels quickly at higher temperatures. Monolithic gel samples were prepared using glycerol as the drying control additive. The gels were subjected to various thermal treatments and characterized by several methods. No organic groups could be detected in the glasses after heat treatments to approx. 800 C, but trace amounts of hydroxyl groups were still present. No crystalline phase was found from X-ray diffraction in the gel samples to approx. 890 C. At higher temperatures, alpha quartz precipitated out as the crystalline phase in gels containing up to 10 mol % MgO. The overall activation energy for gel formation in 10MgO-90SiO2 (mol %) system for water/TEOS mole ratio of 7.5 was calculated to be 58.7 kJ/mol.

  15. Immiscible experiments on the Rayleigh-Taylor instability using simultaneous particle image velocimetry and planar laser induced fluorescence concentration measurements

    NASA Astrophysics Data System (ADS)

    Mokler, Matthew; Jacobs, Jeffrey

    2014-11-01

    Incompressible Rayleigh-Taylor instability experiments are presented in which two stratified liquids having Atwood number of 0.2 are accelerated in a vertical linear induction motor driven drop tower. A test sled having only vertical freedom of motion contains the experiment tank and visualization equipment. The sled is positioned at the top of the tower within the linear induction motors and accelerated downward causing the initially stable interface to be unstable and allowing the Rayleigh-Taylor instability to develop. Forced and unforced experiments are conducted using an immiscible liquid combination. Forced initial perturbations are produced by vertically oscillating the test sled prior to the start of acceleration. The interface is visualized using a 445 nm laser light source that illuminates a fluorescent dye mixed in one of the fluids and aluminum oxide particles dispersed in both fluids. The laser beam is synchronously swept across the fluorescent fluid, at the frame rate of the camera, exposing a single plane of the interface. The resulting images are recorded using a monochromatic high speed video camera. Time dependent velocity and density fields are obtained from the recorded images allowing for 2D full field measurements of turbulent kinetic energy and turbulent mass transport.

  16. Electrically Controllable Microparticle Synthesis and Digital Microfluidic Manipulation by Electric-Field-Induced Droplet Dispensing into Immiscible Fluids.

    PubMed

    Um, Taewoong; Hong, Jiwoo; Im, Do Jin; Lee, Sang Joon; Kang, In Seok

    2016-08-18

    The dispensing of tiny droplets is a basic and crucial process in a myriad of applications, such as DNA/protein microarray, cell cultures, chemical synthesis of microparticles, and digital microfluidics. This work systematically demonstrates droplet dispensing into immiscible fluids through electric charge concentration (ECC) method. It exhibits three main modes (i.e., attaching, uniform, and bursting modes) as a function of flow rates, applied voltages, and gap distances between the nozzle and the oil surface. Through a conventional nozzle with diameter of a few millimeters, charged droplets with volumes ranging from a few μL to a few tens of nL can be uniformly dispensed into the oil chamber without reduction in nozzle size. Based on the features of the proposed method (e.g., formation of droplets with controllable polarity and amount of electric charge in water and oil system), a simple and straightforward method is developed for microparticle synthesis, including preparation of colloidosomes and fabrication of Janus microparticles with anisotropic internal structures. Finally, a combined system consisting of ECC-induced droplet dispensing and electrophoresis of charged droplet (ECD)-driven manipulation systems is constructed. This integrated platform will provide increased utility and flexibility in microfluidic applications because a charged droplet can be delivered toward the intended position by programmable electric control.

  17. Interfacial instabilities in two immiscible flows in an annular duct: Shear-thinning fluids surrounded with Newtonian fluids

    NASA Astrophysics Data System (ADS)

    Ding, Zijing; Liu, Rong; Liu, Zhou

    2017-05-01

    In this paper, the stability of two co-axial immiscible fluids flowing in an annular duct is investigated. The inner layer consists of a shear-thinning fluid, which is surrounded by a Newtonian liquid annulus in the outer layer. A constant pressure gradient is applied to drive the flow in the annular channel. Linear stability analysis is employed to investigate the shear-thinning effect on the Rayleigh-Plateau instability and the interface wave instability. Results show that the Rayleigh-Plateau mode can be enhanced and the topological structures of the marginal stability curve of the Rayleigh-Plateau mode can be significantly changed by the shear-thinning effect. When the shear-thinning effect is strong, a case study shows that the Rayleigh-Plateau instability can be slightly suppressed by the viscosity stratification in the inner layer. The shear-thinning effect has a dual influence on the interface wave instability. It can either enhance or suppress the interface wave instability, depending on the thickness ratio and viscosity ratio between the outer layer and the inner layer.

  18. Identification of immiscible NAPL contaminant sources in aquifers by a modified two-level saturation based imperialist competitive algorithm.

    PubMed

    Ghafouri, H R; Mosharaf-Dehkordi, M; Afzalan, B

    2017-07-01

    A simulation-optimization model is proposed for identifying the characteristics of local immiscible NAPL contaminant sources inside aquifers. This model employs the UTCHEM 9.0 software as its simulator for solving the governing equations associated with the multi-phase flow in porous media. As the optimization model, a novel two-level saturation based Imperialist Competitive Algorithm (ICA) is proposed to estimate the parameters of contaminant sources. The first level consists of three parallel independent ICAs and plays as a pre-conditioner for the second level which is a single modified ICA. The ICA in the second level is modified by dividing each country into a number of provinces (smaller parts). Similar to countries in the classical ICA, these provinces are optimized by the assimilation, competition, and revolution steps in the ICA. To increase the diversity of populations, a new approach named knock the base method is proposed. The performance and accuracy of the simulation-optimization model is assessed by solving a set of two and three-dimensional problems considering the effects of different parameters such as the grid size, rock heterogeneity and designated monitoring networks. The obtained numerical results indicate that using this simulation-optimization model provides accurate results at a less number of iterations when compared with the model employing the classical one-level ICA. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Melt inclusion record of immiscibility between silicate, hydrosaline, and carbonate melts: Applications to skarn genesis at Mount Vesuvius

    NASA Astrophysics Data System (ADS)

    Fulignati, Paolo; Kamenetsky, Vadim S.; Marianelli, Paola; Sbrana, Alessandro; Mernagh, Terrence P.

    2001-11-01

    Foid-bearing syenites and endoskarn xenoliths of the A.D. 472 Vesuvius eruption represent the magma chamber carbonate wall-rock interface. Melt inclusions hosted in crystals from these rocks offer a rare opportunity to depict the formation and the composition of metasomatic skarn-forming fluids at the peripheral part of a growing K-alkaline magma chamber disrupted by an explosive eruption. Four principal types of melt inclusions represent highly differentiated phonolite (type 1), hydrosaline melt (type 3), unmixed silicate salt melts (type 2), and a complex chloride-carbonate melt with minor sulfates (type 4). The high-temperature (700 800 °C) magmatic-derived hydrosaline melt is considered to be the main metasomatic agent for the skarn-forming reactions. The interaction between this melt (fluid) and carbonate wall rocks produces a Na-K-Ca carbonate-chloride melt that shows immiscibility between carbonate and chloride constituents at ˜700 °C in 1 atm experiments. This unmixing can be viewed as a possible mechanism for the origin of carbonatites associated with intrusion-related skarn systems.

  20. Identification of immiscible NAPL contaminant sources in aquifers by a modified two-level saturation based imperialist competitive algorithm

    NASA Astrophysics Data System (ADS)

    Ghafouri, H. R.; Mosharaf-Dehkordi, M.; Afzalan, B.

    2017-07-01

    A simulation-optimization model is proposed for identifying the characteristics of local immiscible NAPL contaminant sources inside aquifers. This model employs the UTCHEM 9.0 software as its simulator for solving the governing equations associated with the multi-phase flow in porous media. As the optimization model, a novel two-level saturation based Imperialist Competitive Algorithm (ICA) is proposed to estimate the parameters of contaminant sources. The first level consists of three parallel independent ICAs and plays as a pre-conditioner for the second level which is a single modified ICA. The ICA in the second level is modified by dividing each country into a number of provinces (smaller parts). Similar to countries in the classical ICA, these provinces are optimized by the assimilation, competition, and revolution steps in the ICA. To increase the diversity of populations, a new approach named knock the base method is proposed. The performance and accuracy of the simulation-optimization model is assessed by solving a set of two and three-dimensional problems considering the effects of different parameters such as the grid size, rock heterogeneity and designated monitoring networks. The obtained numerical results indicate that using this simulation-optimization model provides accurate results at a less number of iterations when compared with the model employing the classical one-level ICA.

  1. Electrically Controllable Microparticle Synthesis and Digital Microfluidic Manipulation by Electric-Field-Induced Droplet Dispensing into Immiscible Fluids

    PubMed Central

    Um, Taewoong; Hong, Jiwoo; Im, Do Jin; Lee, Sang Joon; Kang, In Seok

    2016-01-01

    The dispensing of tiny droplets is a basic and crucial process in a myriad of applications, such as DNA/protein microarray, cell cultures, chemical synthesis of microparticles, and digital microfluidics. This work systematically demonstrates droplet dispensing into immiscible fluids through electric charge concentration (ECC) method. It exhibits three main modes (i.e., attaching, uniform, and bursting modes) as a function of flow rates, applied voltages, and gap distances between the nozzle and the oil surface. Through a conventional nozzle with diameter of a few millimeters, charged droplets with volumes ranging from a few μL to a few tens of nL can be uniformly dispensed into the oil chamber without reduction in nozzle size. Based on the features of the proposed method (e.g., formation of droplets with controllable polarity and amount of electric charge in water and oil system), a simple and straightforward method is developed for microparticle synthesis, including preparation of colloidosomes and fabrication of Janus microparticles with anisotropic internal structures. Finally, a combined system consisting of ECC-induced droplet dispensing and electrophoresis of charged droplet (ECD)-driven manipulation systems is constructed. This integrated platform will provide increased utility and flexibility in microfluidic applications because a charged droplet can be delivered toward the intended position by programmable electric control. PMID:27534580

  2. Electrically Controllable Microparticle Synthesis and Digital Microfluidic Manipulation by Electric-Field-Induced Droplet Dispensing into Immiscible Fluids

    NASA Astrophysics Data System (ADS)

    Um, Taewoong; Hong, Jiwoo; Im, Do Jin; Lee, Sang Joon; Kang, In Seok

    2016-08-01

    The dispensing of tiny droplets is a basic and crucial process in a myriad of applications, such as DNA/protein microarray, cell cultures, chemical synthesis of microparticles, and digital microfluidics. This work systematically demonstrates droplet dispensing into immiscible fluids through electric charge concentration (ECC) method. It exhibits three main modes (i.e., attaching, uniform, and bursting modes) as a function of flow rates, applied voltages, and gap distances between the nozzle and the oil surface. Through a conventional nozzle with diameter of a few millimeters, charged droplets with volumes ranging from a few μL to a few tens of nL can be uniformly dispensed into the oil chamber without reduction in nozzle size. Based on the features of the proposed method (e.g., formation of droplets with controllable polarity and amount of electric charge in water and oil system), a simple and straightforward method is developed for microparticle synthesis, including preparation of colloidosomes and fabrication of Janus microparticles with anisotropic internal structures. Finally, a combined system consisting of ECC-induced droplet dispensing and electrophoresis of charged droplet (ECD)-driven manipulation systems is constructed. This integrated platform will provide increased utility and flexibility in microfluidic applications because a charged droplet can be delivered toward the intended position by programmable electric control.

  3. On the Rigid-Lid Approximation for Two Shallow Layers of Immiscible Fluids with Small Density Contrast

    NASA Astrophysics Data System (ADS)

    Duchêne, Vincent

    2014-08-01

    The rigid-lid approximation is a commonly used simplification in the study of density-stratified fluids in oceanography. Roughly speaking, one assumes that the displacements of the surface are negligible compared with interface displacements. In this paper, we offer a rigorous justification of this approximation in the case of two shallow layers of immiscible fluids with constant and quasi-equal mass density. More precisely, we control the difference between the solutions of the Cauchy problem predicted by the shallow-water (Saint-Venant) system in the rigid-lid and free-surface configuration. We show that in the limit of a small density contrast, the flow may be accurately described as the superposition of a baroclinic (or slow) mode, which is well predicted by the rigid-lid approximation, and a barotropic (or fast) mode, whose initial smallness persists for large time. We also describe explicitly the first-order behavior of the deformation of the surface and discuss the case of a nonsmall initial barotropic mode.

  4. Effect of alpha-cyclodextrin on drug distribution studied by electrochemistry at interfaces between immiscible electrolyte solutions.

    PubMed

    Deryabina, Maria A; Hansen, Steen H; Østergaard, Jesper; Jensen, Henrik

    2009-05-21

    The description and understanding of noncovalent interactions and distribution of potential new drug compounds in an organism is of paramount importance for the successful development of new drugs. In this work, a new procedure based on electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) for addressing and discriminating between drug compound/ligand interactions in aqueous solution and nonspecific ligand effects on oil-water distribution behavior has been developed. The procedure is demonstrated using five drug compounds with different physical chemical parameters and alpha-cyclodextrin as the aqueous phase ligand. Alpha-cyclodextrin was chosen as an aqueous phase ligand, as it is frequently used in drug formulations to enhance solubility and bioavailability of drug compounds. Supplementary capillary electrophoresis experiments provided more detailed information on alpha-cyclodextrin drug complexation and, in combination with the electrochemical studies, provided information on solvation effects affecting the oil-water distribution of the drug compounds. The use of ligand shift ion partition diagrams for data presentation is a convenient format for the visualization of ligand effects on distribution behavior of related drug compounds.

  5. Surrogate Immiscible Liquid Solution Pairs with Refractive Indexes Matchable Over a Wide Range of Density and Viscosity Ratios

    NASA Astrophysics Data System (ADS)

    Saksena, Rajat; Christensen, Kenneth T.; Pearlstein, Arne J.

    2014-11-01

    Use of laser diagnostics in liquid-liquid flows is limited by refractive index mismatch. This can be avoided using a surrogate pair of immiscible index-matched liquids, with density and viscosity ratios matching those of the original liquid pair. We demonstrate that a wide range of density and viscosity ratios is accessible using aqueous solutions of 1,2-propanediol and CsBr (for which index, density, and viscosity are available), and solutions of light and heavy silicone oils and 1-bromooctane (for which we measured the same properties at 119 compositions). For each liquid phase, polynomials in the composition variables were fitted to index and density and to the logarithm of kinematic viscosity, and the fits were used to determine accessible density and viscosity ratios for each matchable index. Index-matched solution pairs can be prepared with density and viscosity ratios equal to those for water-liquid CO2 at 0oC over a range of pressure, and for water-crude oil and water-trichloroethylene, each over a range of temperature. For representative index-matched solutions, equilibration changes index, density, and viscosity only slightly, and chemical analysis show that no component of either solution has significant interphase solubility. Partially supported by Intl. Inst. for Carbon-Neutral Energy Research.

  6. Advances in the engineering science of immiscible polymer blends: A powder route for delicate polymer precursors and a highly renewable polyamide/terephthalate blend system

    NASA Astrophysics Data System (ADS)

    Giancola, Giorgiana

    Powder processing of thermoplastic polymer composites is an effective way to achieve a high level of component homogenization in raw blends prior to melt processing, thus reducing the thermal and shear stress on the components. Polymer blends can be prepared that would otherwise not be possible due to thermodynamic incompatibility. Evaluation of this concept was conducted by processing PMMA and HDPE micron sized powders which were characterized using DSC and rheology. Optical microscopy and SEM, showed that high-quality, fine domain sized blends can be made by the compression molding process. Silica marker spheres were used to qualitatively assess the level dispersive mixing. EDS chemical analysis was effective in providing image contrast between PMMA and HDPE based on the carbonyl and ester oxygen. EDS image maps, combined with secondary electron images show that compression molding of blended powder precursors produces composites of comparable homogeneity and domain size as extrusion processing. FTIR proved valuable when assessing the intimacy of the constituents at the interface of the immiscible domains. The formation of an in-situ, PMMA nano-network structure resulting from solvent extraction and redeposition using DMF was uniquely found on the surface of these immiscible polymer blends. This work has shown that powder processing of polymers is an effective means to melt processed fragile polymers to high quality blends. Recently, efforts towards the development of sustainable materials have evolved due in part to the increase in price and limited supply of crude oil. Immiscible polymer blending is a paradigm that enables synergistic material performance in certain instances where the composite properties are superior to the sum of the constituents. The addition of PA6,10 to PTT offers an opportunity to increase the bio-based content of PTT while simultaneously maintaining or improving mechanical properties. PA6,10 and PTT are immiscible polymers that can be

  7. Variolites - results of liquid immiscibility or mingling?: Evidence from variolitic lava, axial part of the Mid-Atlantic Ridge, 6oN

    NASA Astrophysics Data System (ADS)

    Sharkov, E. V.

    2010-12-01

    Fragment of variolitic lavas was dredged in axial part of the MAR at 6oN during 10th cruise of R/V “Akademik Ioffe” (2001-2002). It is rock where rounded globules of andesite (icelandite) with light trachyandesite rims are enclosed in Fe-Ti picrobasalt matrix. The sample can be subdivided in two different structural parts or “layers”. One of them densely saturated by globules, which closely adjoin to each other, merge in clumpy congregations; in another part matrix predominates. Boundary between both parts, even if irregular due to rounded shape of closed globules, nevertheless is well-defined and has small bays of the matrix material. So, globules were moved in picrobasaltic melt and floated up to the surface of the lava flow. It is shown that formation of the leucocratic rims was evidently linked with thermal diffusion phenomenon (Soret principle) in cooling heterogeneous melt. According to this principle, components in solutions and melts, placed in thermal gradient, are redistributed for leveling of internal energy in that way, when light elements migrate to hot parts and heavy ones to cold. Experimental studies of thermal diffusion in samples of MORB showed enlarge of Si, Al, Na and K concentration to side of hot area of melt and Fe, Mg, Ca, etc. to cold one; resulting melts were andesites and Ne-normative picrite (Walker, DeLong, 1982). The same picture we saw in our sample: enrichment of external zone of globules by Si, Al, and, especially, by high-mobile Na, which diffusion rate in silicate melts in some order higher than speed of remaining elements (Watson, 1982; Borisov, 2008). Simultaneously, this zone impoverished by Fe, Ca and Mg, which were concentrated in rear of rims, forming internal zoning of globules with careless boundaries. Effect of thermal diffusion in more important for Fe; as a result #mg in trachyandesite rims higher than in andesite cores of globules. It suggests that origin of variolites was linked with intersection by ascended

  8. Interfacial tension between immiscible melts in the system K2O - FeO - Fe2O3 - Al2O3 - SiO2

    NASA Astrophysics Data System (ADS)

    Kaehn, J.; Veksler, I. V.; Franz, G.; Dingwell, D. B.

    2009-12-01

    Interfacial tension is a very important parameter of the kinetics of phase nucleation, dissolution and growth. Excess surface energy contributes to the energy barrier for phase nucleation, and works as the main driving force for minimization of phase contact surfaces in heterogeneous systems. Immiscible silicate melts have been found to form in a broad range of basaltic, dacitic and rhyolitic magmas (Philpotts, 1982). However, liquid-liquid interfaces remain poorly studied in comparison with crystal-melt and vapor-melt interfaces. Here we present first experimental measurements of interfacial tension between synthetic Fe-rich and silica-rich immiscible melts composed of Fe oxides, K2O, alumina and silica. According to Naslund (1983), the miscibility gap in the 5-oxide system expands with increasing fO2 and becomes widest in air (fO2 = 0.2). Our goal was to estimate the maximal liquid-liquid interfacial tension for the immiscible liquids composed of silica and Fe oxides. Therefore, we have chosen the most contrasting liquid compositions that coexist in air at and above 1465 °C. Silica-rich and Fe-rich conjugate liquids at these conditions contain 73 and 17 wt. % SiO2, and 14 and 80 wt. % FeOt, respectively. These starting compositions were synthesized by fusion of reagent-grade oxides and K2CO3 at 1600 °C. In addition to interfacial tension, we have measured density and surface tension of individual coexisting liquids. All the measurements were done at 1500, 1527 and 1550 °C. Density was measured by the Archimedean method; surface and interfacial tensions were calculated from the maximal pool on a vertical cylinder (a 3-mm Pt rod attached to a high precision balance). We found interfacial tension between the immiscible liquids to decrease with increasing temperature from 16.4±2 mN/m at 1500 °C to 8.2±0.8 mN/m at 1550 °C. These values are approximately 2 orders of magnitude lower than typical interfacial tensions between silicate melts and crystals (Wanamaker

  9. Elemental metabolomics.

    PubMed

    Zhang, Ping; Georgiou, Constantinos A; Brusic, Vladimir

    2017-01-10

    Elemental metabolomics is quantification and characterization of total concentration of chemical elements in biological samples and monitoring of their changes. Recent advances in inductively coupled plasma mass spectrometry have enabled simultaneous measurement of concentrations of > 70 elements in biological samples. In living organisms, elements interact and compete with each other for absorption and molecular interactions. They also interact with proteins and nucleotide sequences. These interactions modulate enzymatic activities and are critical for many molecular and cellular functions. Testing for concentration of > 40 elements in blood, other bodily fluids and tissues is now in routine use in advanced medical laboratories. In this article, we define the basic concepts of elemental metabolomics, summarize standards and workflows, and propose minimum information for reporting the results of an elemental metabolomics experiment. Major statistical and informatics tools for elemental metabolomics are reviewed, and examples of applications are discussed. Elemental metabolomics is emerging as an important new technology with applications in medical diagnostics, nutrition, agriculture, food science, environmental science and multiplicity of other areas. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Tuning structural motifs and alloying of bulk immiscible Mo-Cu bimetallic nanoparticles by gas-phase synthesis

    NASA Astrophysics Data System (ADS)

    Krishnan, Gopi; Verheijen, Marcel A.; Ten Brink, Gert H.; Palasantzas, George; Kooi, Bart J.

    2013-05-01

    Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still remains a formidable challenge. Hence, we present here a general methodology for gas phase synthesis of bimetallic NPs with distinctively different structural motifs ranging at a single particle level from a fully mixed alloy to core-shell, to onion (multi-shell), and finally to a Janus/dumbbell, with the same overall particle composition. These concepts are illustrated for Mo-Cu NPs, where the precise control of the bimetallic NPs with various degrees of chemical ordering, including different shapes from spherical to cube, is achieved by tailoring the energy and thermal environment that the NPs experience during their production. The initial state of NP growth, either in the liquid or in the solid state phase, has important implications for the different structural motifs and shapes of synthesized NPs. Finally we demonstrate that we are able to tune the alloying regime, for the otherwise bulk immiscible Mo-Cu, by achieving an increase of the critical size, below which alloying occurs, closely up to an order of magnitude. It is discovered that the critical size of the NP alloy is not only affected by controlled tuning of the alloying temperature but also by the particle shape.Nowadays bimetallic nanoparticles (NPs) have emerged as key materials for important modern applications in nanoplasmonics, catalysis, biodiagnostics, and nanomagnetics. Consequently the control of bimetallic structural motifs with specific shapes provides increasing functionality and selectivity for related applications. However, producing bimetallic NPs with well controlled structural motifs still

  11. Linear stability analysis of immiscible two-phase flow in porous media with capillary dispersion and density variation

    NASA Astrophysics Data System (ADS)

    Riaz, Amir; Tchelepi, Hamdi A.

    2004-12-01

    Linear stability analysis of immiscible displacements is carried out for both viscously and gravitationally unstable two-phase flows in porous media with very large adverse viscosity ratios. Capillary dispersion is the proper dissipative mechanism in this case which sets both the preferred length scale and the band width of the spectrum of unstable length scales. The growth rate, the most dangerous and the cutoff wavenumbers, all scale linearly with the capillary number. We show that the instability is governed by fluid properties across the shock rather than those across the full Buckley-Leverett profile. The shock total mobility ratio provides a sufficient condition for the onset of instability; however, it is not an appropriate criterion for predicting the magnitude of the growth rate, particularly for large viscosity ratios. The details of the relative permeability functions are observed to have a significant influence on the stability characteristics. For neutrally buoyant flows the maximum growth rate scales linearly with the viscosity ratio while the most dangerous and the cutoff wavenumbers scale with the square root of the viscosity ratio. In the case of displacements with density contrast, the maximum growth rate scales with the square of the unstable gravity number while the most dangerous and the cutoff wavenumbers scale with an exponent of 1.2, for all viscosity ratios. A marginal stability curve is computed for stable and unstable regions in the parameter space of the viscosity ratio and the gravity number. It is found that flows with unstable viscosity contrasts are more readily stabilized with buoyancy as compared to the viscous stabilization of gravitationally unstable flows.

  12. Conductivity and phase morphology of carbon black-filled immiscible polymer blends under creep: an experimental and theoretical study.

    PubMed

    Pan, Yamin; Liu, Xianhu; Hao, Xiaoqiong; Schubert, Dirk W

    2016-11-30

    Blends of carbon black (CB)-filled co-continuous immiscible polystyrene/poly(methyl-methacrylate) (PS/PMMA) with a PS/PMMA ratio of 50/50 and CB selectively located in the PS phase have been prepared by melt blending. The simultaneous evolution of conductivity and phase morphology of blend composites was investigated under shear and in the quiescent state at 200 °C. It was found that shear deformation had a significant influence on the conductivity of the unfilled PS/PMMA blend and its composites, which was attributed to the change of phase morphology during shear. After the shear stress of 10 kPa, the conductivity of PS/PMMA blends filled with 2 vol% of CB decreased by about two orders of magnitude and the phase morphology transformed from a fine co-continuous structure into a highly elongated lamellar structure. The deformation of phase morphology and the decrease of conductivity were weakened upon decreasing the shear stress or increasing the CB concentration. During subsequent recovery, pronounced phase structure coarsening was observed in the mixture and the conductivity increased as well. A simple model describing the behavior of conductivity under shear deformation was derived and utilized for the description of the experimental data. For the first time, the Burgers model was used to describe the conductivity, and the viscoelastic and viscoplastic parameters were deduced by fitting the conductivity under shear. The results obtained in this study provide a deeper insight into the evolution of phase structure in the conductive polymer blend composite induced by shear deformation.

  13. Laboratory and numerical investigations of kinetic interface sensitive tracers transport for immiscible two-phase flow porous media systems

    NASA Astrophysics Data System (ADS)

    Tatomir, Alexandru Bogdan A. C.; Sauter, Martin

    2017-04-01

    A number of theoretical approaches estimating the interfacial area between two fluid phases are available (Schaffer et al.,2013). Kinetic interface sensitive (KIS) tracers are used to describe the evolution of fluid-fluid interfaces advancing in two phase porous media systems (Tatomir et al., 2015). Initially developed to offer answers about the supercritical (sc)CO2 plume movement and the efficiency of trapping in geological carbon storage reservoirs, KIS tracers are tested in dynamic controlled laboratory conditions. N-octane and water, analogue to a scCO2 - brine system, are used. The KIS tracer is dissolved in n-octane, which is injected as the non-wetting phase in a fully water saturated porous media column. The porous system is made up of spherical glass beads with sizes of 100-250 μm. Subsequently, the KIS tracer follows a hydrolysis reaction over the n-octane - water interface resulting in an acid and phenol which are both water soluble. The fluid-fluid interfacial area is described numerically with the help of constitutive-relationships derived from the Brooks-Corey model. The specific interfacial area is determined numerically from pore scale calculations, or from different literature sources making use of pore network model calculations (Joekar-Niasar et al., 2008). This research describes the design of the laboratory setup and compares the break-through curves obtained with the forward model and in the laboratory experiment. Furthermore, first results are shown in the attempt to validate the immiscible two phase flow reactive transport numerical model with dynamic laboratory column experiments. Keywords: Fluid-fluid interfacial area, KIS tracers, model validation, CCS, geological storage of CO2

  14. Mission Immiscible: Distinct subduction components generate two primary magmas of Pagan Volcano, Mariana arc

    NASA Astrophysics Data System (ADS)

    Tamura, Y.; Ishizuka, O.; Stern, R. J.; Nunokawa, A.; Shukuno, H.; Kawabata, H.; Hirahara, Y.; Chang, Q.; Miyazaki, T.; Kimura, J.; Embley, R. W.; Bloomer, S. H.; Tatsumi, Y.

    2012-12-01

    Pagan is one of the largest (2,160 km3; Bloomer et al., 1989) volcanoes along the Mariana arc magmatic front. Pagan has a maximum elevation of 570 m (Mt. Pagan), but its submarine flanks descend to 2,000-3,000 m, and most of the volcano is submarine and unexplored. Bathymetric mapping and ROV Hyper-Dolphin (HPD1147) dive on the NE submarine flank of Pagan were carried out during NT10-12 (R/V Natsushima) in July 2010. There are no systematic differences between subaerial and submarine lavas with > 52 wt % SiO2, suggesting derivation from the same magmatic system. Twenty least-fractionated basalts (48.5-50 wt % SiO2) extend to higher MgO (10-11 wt %) and Mg# (66-70) than subaerial lavas. Compositions of olivine (up to Fo94) and spinels (Cr# up to 0.8) suggest that Pagan primitive magmas formed from high degrees of mantle melting. Two geochemical groups of basalts can be distinguished at similar 10-11 wt % MgO; these erupted about the same time, 500 m apart. Both contain clinopyroxene and olivine phenocrysts, thus, these two groups are referred to as COB1 and COB2. Lower TiO2, FeO, Na2O, K2O, incompatible trace element abundances, and Nb/Yb suggest that COB1 formed from higher degrees of mantle melting. In addition, LREE-enrichment and higher Th/Nb in COB2 contrast with LREE-depletion and lower Th/Nb in COB1. Higher Ba/Th and Ba/Nb and lower Th/Nb indicate that main subduction addition in COB1 was dominated by hydrous fluid, whereas that in COB2 was dominated by sediment melt. Sr-Nd-Pb-Hf isotopes are also consistent with this scenario. Importantly, the subduction addition, that caused more melting of the COB1 source was mostly hydrous fluid. In contrast to Pagan, we observed two primary magmas (COB and POB) in the NW Rota-1 volcano (NWR1), ~40 km behind the volcanic front. NWR1 COB has a greater subduction component, both hydrous fluid and sediment melt, than POB, perhaps reflecting that the subducting slab below NWR1 is > 100 km deeper than that beneath Pagan. At

  15. Elemental health

    SciTech Connect

    Tonneson, L.C.

    1997-01-01

    Trace elements used in nutritional supplements and vitamins are discussed in the article. Relevant studies are briefly cited regarding the health effects of selenium, chromium, germanium, silicon, zinc, magnesium, silver, manganese, ruthenium, lithium, and vanadium. The toxicity and food sources are listed for some of the elements. A brief summary is also provided of the nutritional supplements market.

  16. Immiscibility between calciocarbonatitic and silicate melts and related wall rock reactions in the upper mantle: a natural case study from Romanian mantle xenoliths

    NASA Astrophysics Data System (ADS)

    Chalot-Prat, Françoise; Arnold, Michel

    1999-04-01

    This paper presents the textural, mineralogical and chemical study of veinlets cross-cutting peridotite xenoliths from the lithospheric mantle and brought to the surface by alkaline basalts (Persani Mountains, Romania). The veinlets utilized pre-existing zones of weakness in the host rocks or display a random distribution, lining grain boundaries or cross-cutting any mineral, and always forming an interconnected network. They are filled with carbonate patches included in a silicate matrix. Both products are holocrystalline. Carbonate products have alkali-poor calciocarbonatitic to sövitic compositions, while the silicate matrix composition ranges from monzodioritic to monzonitic and alkali feldspar syenitic, depending on the host-sample, i.e., within a rather alkaline silica-saturated series. The mineral phases present in the silicate matrix (F-apatite, armalcolite, chromite, diopside-enstatite series, plagioclase-sanidine series) are usually present in the carbonate zones, where forsterite is also found. Some minerals cross-cut the interface between both types of zones. Only the matrix is different, feldspathic (oligoclase to sanidine) in the former and pure calcite in the latter. Thus, mineralogical and textural relationships between both products are consistent with an origin with equilibrium liquid immiscibility. Mantle minerals cross-cut by veinlets are sometimes resorbed at grain boundaries, and at the contact of the most alkaline silicate and carbonate melts, subhedral diopside/augite formed at the expense of mantle enstatite or olivine. In terms of mineral chemistry, the compositional variations recorded by vein minerals vary along a continuous trend. They generally superpose to those observed from lherzolites to harzburgites, and exhibit the same range of composition as that observed between rims and cores of mantle minerals cross-cut by veinlets. In detail, the Ca-rich pyroxenes of veinlets are Al-poor and Mg-rich; cpx in the carbonate zones are slightly

  17. The use of rheology to elucidate the granulation mechanisms of a miscible and immiscible system during continuous twin-screw melt granulation.

    PubMed

    Monteyne, Tinne; Heeze, Liza; Mortier, Séverine Thérèse F C; Oldörp, Klaus; Nopens, Ingmar; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-08-20

    Twin-screw hot melt granulation (TS HMG) is a valuable, but still unexplored alternative to granulate temperature and moisture sensitive drugs in a continuous way. Recently, the material behavior of an immiscible drug-binder blend during TS HMG was unraveled by using a rheometer and differential scanning calorimetry (DSC). Additionally, vibrational spectroscopic techniques proved the link between TS HMG and rheology since equal interactions at molecular level did occur in both processes. This allowed to use a rheometer to gain knowledge of the material behavior during hot melt processing of an immiscible drug-binder blend. However, miscibility of a drug-binder formulation and drug-binder interactions appear to influence the rheological properties and, hence conceivably also the granulation mechanism. The aim of this research was to examine if the TS HMG process of a miscible formulation system is comparable with the mechanism of an immiscible system and to evaluate whether rheology still serves as a useful tool to understand and optimize the hot melt granulation (HMG) process. The executed research (thermal analysis, rheological parameters and spectroscopic data) demonstrated the occurrence of a high and broad tan(δ) curve without a loss peak during the rheological temperature ramp which implies a higher material deformability without movement of the softened single polymer chains. Spectroscopic analysis revealed drug-polymer interactions which constrain the polymer to flow independently. As a result, the binder distribution step, which generally follows the immersion step, was hindered. This insight assisted the understanding of the granule properties. Inhomogeneous granules were produced due to large initial nuclei or adhesion of multiple smaller nuclei. Consequently, a higher granulation temperature was required in order to get the binder more homogeneously distributed within the granules.

  18. A review of experimental studies of crystal/liquid trace element partitioning

    NASA Technical Reports Server (NTRS)

    Irving, A. J.

    1978-01-01

    Experimental techniques for examining trace-element behavior are reviewed. Applications of these techniques are described for a variety of partition coefficients including: olivine/liquid, subcalcic pyroxene/liquid, calcic pyroxene/liquid, amphibole/liquid, plagioclase/liquid, alkali feldspar/liquid, garnet/liquid, apatite/liquid and whitlockite/liquid, ilmenite/liquid, armalcolite/liquid and pseudobrookite/liquid, magnetite/liquid and spinel/liquid, perovskite/liquid, and melilite/liquid partition coefficients. Partition coefficients between immiscible liquids are discussed and suggestions for further work are noted. A detailed bibliography is included.

  19. Defect-Resistant Radiative Performance of m-Plane Immiscible Al1-x Inx N Epitaxial Nanostructures for Deep-Ultraviolet and Visible Polarized Light Emitters.

    PubMed

    Chichibu, Shigefusa F; Kojima, Kazunobu; Uedono, Akira; Sato, Yoshitaka

    2017-02-01

    Planar vacuum-fluorescent-display devices emitting polarized UV-C, blue, and green light are demonstrated using immiscible Al1-x Inx N nanostructures grown in nonpolar m-directions. Despite the presence of high concentration of nonradiative recombination centers, the Al1-x Inx N nanostructures emit polarized light with the luminescence lifetimes of 22-32 ps at 300 K. This defect-resistant radiative performance suggests supernormal localized characteristics of electron-hole pairs. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. CO2-rich phonolitic melt and carbonatite immiscibility in melt inclusions in nephelinite (Hanang volcano, North Tanzanian Divergence, East African Rift).

    NASA Astrophysics Data System (ADS)

    Baudouin, C.; Parat, F.

    2016-12-01

    Hanang is the southern volcano of the East branch of the East African Rift and represents volcanic activity at early stage rifting (0.9 Ma). Lavas are highly alkaline Mg-poor nephelinites (Mg#=24.4-35.2) with cpx, garnet, nepheline, titanite, and apatite and result from fractional crystallisation of primary melilitite magmas (Parat et al. AGU2016). In this study, we investigate glassy melt inclusions at the rim of nepheline phenocrysts to constrain the late stage of nephelinite evolution and the behaviour of volatiles (CO2, H2O, S, F, Cl) during magma storage and ascent. The melt inclusions have a green silicate glass, a microcrystalline carbonate phase and a shrinkage bubble free of gas phase (Raman analyses) suggesting that carbonatite-silicate liquid immiscibility (85:15) occurred during nephelinite differentiation. The silicate glasses have trachytic composition (Na+K/Al=1.6-7.2, SiO2=54-65.5 wt%) with high CO2 (0.43 wt% CO2, SIMS analyses), sulfur (0.21-0.92 wt% S) and halogens (0.28-0.84 wt% Cl; 0.35-2.54 wt% F) content and very low H2O content (<0.1wt%, Raman analyses). The carbonate phase is an anhydrous Ca-Na±S,K- carbonate with 33 wt% CaO, 20 wt% Na2O, 3 wt% K2O, and 3 wt% S. The pre-immiscible silicate liquid (e.g. silicate melt + carbonatite) in equilibrium with nepheline and cpx phenocrysts has CO2-rich phonolitic composition (Na+K/Al=6.2-6.9) with 6 ± 1.5 wt% CO2 at pressure of 700-1100 MPa. The entrapped melt in nepheline corresponds to evolved interstitial silicate melt after crystallisation of cpx (16.7%), nepheline (40%) garnet (6.5%) and apatite (1.7%) from Mg-nephelinite magma. The immiscibility process leading to glassy silicate melt and microcrystalline carbonatitic melt occurred in closed system during rapid ascent at crustal level at 200-230 MPa. The absence of gas phase in shrinkage bubble in melt inclusions suggests CO2-undersaturated conditions during quenching. The absence of carbonatite lavas at Hanang volcano is then explained by

  1. Lattice Boltzmann simulation of the flow of binary immiscible fluids with different viscosities using the Shan-Chen microscopic interaction model.

    PubMed

    Chin, Jonathan; Boek, Edo S; Coveney, Peter V

    2002-03-15

    We present a lattice Boltzmann study of the flow of a binary fluid where the fluid components have different viscosities. For this purpose, a microscopic interaction model (due to Shan & Chen) is used. The model is validated for Poiseuille flow of layered immiscible binary fluids and the dispersion of a capillary wave. We then study the unstable displacement of a viscous fluid by a less viscous fluid in a two-dimensional channel. Although a finger-like structure was observed in many simulations, it is not clear if this structure was produced due to viscous fingering or due to other effects.

  2. Superheavy Elements

    ERIC Educational Resources Information Center

    Tsang, Chin Fu

    1975-01-01

    Discusses the possibility of creating elements with an atomic number of around 114. Describes the underlying physics responsible for the limited extent of the periodic table and enumerates problems that must be overcome in creating a superheavy nucleus. (GS)

  3. Elemental Education.

    ERIC Educational Resources Information Center

    Daniel, Esther Gnanamalar Sarojini; Saat, Rohaida Mohd.

    2001-01-01

    Introduces a learning module integrating three disciplines--physics, chemistry, and biology--and based on four elements: carbon, oxygen, hydrogen, and silicon. Includes atomic model and silicon-based life activities. (YDS)

  4. Elemental Education.

    ERIC Educational Resources Information Center

    Daniel, Esther Gnanamalar Sarojini; Saat, Rohaida Mohd.

    2001-01-01

    Introduces a learning module integrating three disciplines--physics, chemistry, and biology--and based on four elements: carbon, oxygen, hydrogen, and silicon. Includes atomic model and silicon-based life activities. (YDS)

  5. Superheavy Elements

    ERIC Educational Resources Information Center

    Tsang, Chin Fu

    1975-01-01

    Discusses the possibility of creating elements with an atomic number of around 114. Describes the underlying physics responsible for the limited extent of the periodic table and enumerates problems that must be overcome in creating a superheavy nucleus. (GS)

  6. Element 117

    SciTech Connect

    2010-04-08

    An international team of scientists from Russia and the United States, including two Department of Energy national laboratories and two universities, has discovered the newest superheavy element, element 117. The team included scientists from the Joint Institute of Nuclear Research (Dubna, Russia), the Research Institute for Advanced Reactors (Dimitrovgrad), Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt University, and the University of Nevada, Las Vegas.

  7. Element 117

    ScienceCinema

    None

    2016-09-30

    An international team of scientists from Russia and the United States, including two Department of Energy national laboratories and two universities, has discovered the newest superheavy element, element 117. The team included scientists from the Joint Institute of Nuclear Research (Dubna, Russia), the Research Institute for Advanced Reactors (Dimitrovgrad), Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, Vanderbilt University, and the University of Nevada, Las Vegas.

  8. Characteristic-based and interface-sharpening algorithm for high-order simulations of immiscible compressible multi-material flows

    NASA Astrophysics Data System (ADS)

    He, Zhiwei; Tian, Baolin; Zhang, Yousheng; Gao, Fujie

    2017-03-01

    The present work focuses on the simulation of immiscible compressible multi-material flows with the Mie-Grüneisen-type equation of state governed by the non-conservative five-equation model [1]. Although low-order single fluid schemes have already been adopted to provide some feasible results, the application of high-order schemes (introducing relatively small numerical dissipation) to these flows may lead to results with severe numerical oscillations. Consequently, attempts to apply any interface-sharpening techniques to stop the progressively more severe smearing interfaces for a longer simulation time may result in an overshoot increase and in some cases convergence to a non-physical solution occurs. This study proposes a characteristic-based interface-sharpening algorithm for performing high-order simulations of such flows by deriving a pressure-equilibrium-consistent intermediate state (augmented with approximations of pressure derivatives) for local characteristic variable reconstruction and constructing a general framework for interface sharpening. First, by imposing a weak form of the jump condition for the non-conservative five-equation model, we analytically derive an intermediate state with pressure derivatives treated as additional parameters of the linearization procedure. Based on this intermediate state, any well-established high-order reconstruction technique can be employed to provide the state at each cell edge. Second, by designing another state with only different reconstructed values of the interface function at each cell edge, the advection term in the equation of the interface function is discretized twice using any common algorithm. The difference between the two discretizations is employed consistently for interface compression, yielding a general framework for interface sharpening. Coupled with the fifth-order improved accurate monotonicity-preserving scheme [2] for local characteristic variable reconstruction and the tangent of hyperbola

  9. Probing the water distribution in porous model sands with two immiscible fluids: A nuclear magnetic resonance micro-imaging study

    NASA Astrophysics Data System (ADS)

    Lee, Bum Han; Lee, Sung Keun

    2017-10-01

    The effect of the structural heterogeneity of porous networks on the water distribution in porous media, initially saturated with immiscible fluid followed by increasing durations of water injection, remains one of the important problems in hydrology. The relationship among convergence rates (i.e., the rate of fluid saturation with varying injection time) and the macroscopic properties and structural parameters of porous media have been anticipated. Here, we used nuclear magnetic resonance (NMR) micro-imaging to obtain images (down to ∼50 μm resolution) of the distribution of water injected for varying durations into porous networks that were initially saturated with silicone oil. We then established the relationships among the convergence rates, structural parameters, and transport properties of porous networks. The volume fraction of the water phase increases as the water injection duration increases. The 3D images of the water distributions for silica gel samples are similar to those of the glass bead samples. The changes in water saturation (and the accompanying removal of silicone oil) and the variations in the volume fraction, specific surface area, and cube-counting fractal dimension of the water phase fit well with the single-exponential recovery function { f (t) = a [ 1 -exp (- λt) ] } . The asymptotic values (a, i.e., saturated value) of the properties of the volume fraction, specific surface area, and cube-counting fractal dimension of the glass bead samples were greater than those for the silica gel samples primarily because of the intrinsic differences in the porous networks and local distribution of the pore size and connectivity. The convergence rates of all of the properties are inversely proportional to the entropy length and permeability. Despite limitations of the current study, such as insufficient resolution and uncertainty for the estimated parameters due to sparsely selected short injection times, the observed trends highlight the first

  10. Theoretical and experimental study of metastable solid solutions and phase stability within the immiscible Ag-Mo binary system

    NASA Astrophysics Data System (ADS)

    Sarakinos, K.; Greczynski, G.; Elofsson, V.; Magnfält, D.; Högberg, H.; Alling, B.

    2016-03-01

    Metastable solid solutions are phases that are synthesized far from thermodynamic equilibrium and offer a versatile route to design materials with tailor-made functionalities. One of the most investigated classes of metastable solid solutions with widespread technological implications is vapor deposited ternary transition metal ceramic thin films (i.e., nitrides, carbides, and borides). The vapor-based synthesis of these ceramic phases involves complex and difficult to control chemical interactions of the vapor species with the growing film surface, which often makes the fundamental understanding of the composition-properties relations a challenging task. Hence, in the present study, we investigate the phase stability within an immiscible binary thin film system that offers a simpler synthesis chemistry, i.e., the Ag-Mo system. We employ magnetron co-sputtering to grow Ag1-xMox thin films over the entire composition range along with x-ray probes to investigate the films structure and bonding properties. Concurrently, we use density functional theory calculations to predict phase stability and determine the effect of chemical composition on the lattice volume and the electronic properties of Ag-Mo solid solutions. Our combined theoretical and experimental data show that Mo-rich films (x ≥ ˜0.54) form bcc Mo-Ag metastable solid solutions. Furthermore, for Ag-rich compositions (x ≤ ˜0.21), our data can be interpreted as Mo not being dissolved in the Ag fcc lattice. All in all, our data show an asymmetry with regards to the mutual solubility of Ag and Mo in the two crystal structures, i.e., Ag has a larger propensity for dissolving in the bcc-Mo lattice as compared to Mo in the fcc-Ag lattice. We explain these findings in light of isostructural short-range clustering that induces energy difference between the two (fcc and bcc) metastable phases. We also suggest that the phase stability can be explained by the larger atomic mobility of Ag atoms as compared to that

  11. ASSESSMENT OF THE ABILITY OF STANDARD SLURRY PUMPS TO MIX MISCIBLE AND IMMISCIBLE LIQUIDS IN TANK 50H

    SciTech Connect

    Poirier, M.

    2011-06-15

    Tank 50H is the feed tank for the Saltstone Production Facility (SPF). At present, Tank 50H contains two standard slurry pumps and two Quad Volute slurry pumps. Current requirements and mixing operation is to run three pumps for one hour prior to initiating a feed transfer to SPF. Savannah River Site (SRS) Liquid Waste would like to move one or both of the Quad Volute pumps from Tank 50H to Tank 51H to replace pumps in Tank 51H that are failing. In addition, one of the standard pumps in Tank 50H exhibits high seal leakage and vibration. SRS Liquid Waste requested Savannah River National (SRNL) to conduct a study to evaluate the feasibility of mixing the contents of Tank 50H with one to three standard slurry pumps. To determine the pump requirements to blend miscible and immiscible liquids in Tank 50H, the author reviewed the pilot-scale blending work performed for the Salt Disposition Integration Project (SDIP) and the technical literature, and applied the results to Tank 50H to determine the number, size, and operating parameters needed to blend the tank contents. The conclusions from this analysis are: (1) A single rotating standard slurry pump (with a 13.6 ft{sup 2}/s U{sub 0}D) will be able to blend miscible liquids (i.e., salt solution) in Tank 50H within 4.4 hours. (2) Two rotating standard slurry pumps will be able to blend miscible liquids in Tank 50H within 3.1 hours. (3) Three rotating standard slurry pumps will be able to blend miscible liquids in Tank 50H within 2.5 hours. (4) A single rotating standard slurry pump (with a 13.6 ft{sup 2}/s U{sub 0}D) will disperse Isopar L{reg_sign} droplets that are less than or equal to 15 micron in diameter. If the droplets are less than 15 micron, they will be dispersed within 4.4 hours. Isopar L{reg_sign} provides a lower bound on the maximum size of droplets that will be dispersed by the slurry pumps in Tank 50H. (5) Two rotating standard slurry pumps will disperse Isopar L{reg_sign} droplets less than 15 micron

  12. Multiscale level-set method for accurate modeling of immiscible two-phase flow with deposited thin films on solid surfaces

    NASA Astrophysics Data System (ADS)

    Abu-Al-Saud, Moataz O.; Riaz, Amir; Tchelepi, Hamdi A.

    2017-03-01

    We developed a multiscale sharp-interface level-set method for immiscible two-phase flow with a pre-existing thin film on solid surfaces. The lubrication approximation theory is used to model the thin-film equation efficiently. The incompressible Navier-Stokes, level-set, and thin-film evolution equations are coupled sequentially to capture the dynamics occurring at multiple length scales. The Hamilton-Jacobi level-set reinitialization is employed to construct the signed-distance function, which takes into account the deposited thin-film on the solid surface. The proposed multiscale method is validated and shown to match the augmented Young-Laplace equation for a static meniscus in a capillary tube. Viscous bending of the advancing interface over the precursor film is captured by the proposed level-set method and agrees with the Cox-Voinov theory. The advancing bubble surrounded by a wetting film inside a capillary tube is considered, and the predicted film thickness compares well with both theory and experiments. We also demonstrate that the multiscale level-set approach can model immiscible two-phase flow with a capillary number as low as 10-6.

  13. A note on the visualization of wetting film structures and a nonwetting immiscible fluid in a pore network micromodel using a solvatochromic dye

    SciTech Connect

    Grate, Jay W.; Zhang, Changyong; Wietsma, Thomas W.; Warner, Marvin G.; Anheier, Norman C.; Bernacki, Bruce E.; Orr, Galya; Oostrom, Martinus

    2010-11-23

    Nile Red is demonstrated as a single dye whose solvatochromism enables selective visualization of two immiscible liquid fluids in a micromodel containing a homogeneous array of pillars creating a porous network. Nile Red dissolves in and partitions between hexadecane as a nonwetting fluid and PEG200 as a hydrophilic fluid that wets the silicon oxide surfaces in the micromodel. Both the absorption spectra and fluorescence emission spectra are sensitive to the solvent environment, such that the two phases can be distinguished by the observed color or the fluorescence emission band. Bright field, hyperspectral, epifluorescence, and confocal fluorescence methods were used to image the micromodel after displacing PEG200 in the model with hexadecane. The use of Nile Red with these imaging methods facilitates visualization of phase identity at specific locations; the interfaces between the two immiscible liquid phases; wetting behavior of the wetting phase within the porous structure; and retention of the wetting phase as thin films around pillars and as bridges across the pore throats. The pillars and wetting phase bridges create a network of obstacles defining a tortuous preferential flow path for the nonwetting phase.

  14. FUEL ELEMENT

    DOEpatents

    Bean, R.W.

    1963-11-19

    A ceramic fuel element for a nuclear reactor that has improved structural stability as well as improved cooling and fission product retention characteristics is presented. The fuel element includes a plurality of stacked hollow ceramic moderator blocks arranged along a tubular raetallic shroud that encloses a series of axially apertured moderator cylinders spaced inwardly of the shroud. A plurality of ceramic nuclear fuel rods are arranged in the annular space between the shroud and cylinders of moderator and appropriate support means and means for directing gas coolant through the annular space are also provided. (AEC)

  15. Trace element partitioning in Fe-P-O-S alloy systems

    NASA Astrophysics Data System (ADS)

    Han, J.; Crispin, K. L.; Ash, R. D.; McDonough, W. F.; Van Orman, J. A.

    2013-12-01

    An understanding of siderophile trace element partitioning between liquid and solid metal phases and between immiscible liquid metal phases is a key to studying the differentiation of planetary and asteroidal cores. Cores are thought to contain non-metallic 'light' elements like S, P, C and N and Si or / and O which may strongly affect the partitioning behavior of trace elements. In a complex system with multiple light elements, each of these non-metallic elements may have a different influence on the partitioning behavior of the trace elements. However, these influences have not been quantified in most cases. We investigated the partitioning behavior of trace elements within the Fe-P-O-S system with varying concentrations of P, O and S. The experiments were performed under pressures ranging from 1 atm to 2 GPa and temperatures varying from 1000°C to 1300°C. The influence of each light element (i.e. P, O, S) on trace element partitioning and their combined effects have been examined. Some highly siderophile elements including Os, Re, and Ir are strongly repelled by sulfur but even more strongly repelled by oxygen. It is possible that these elements could be fractionated significantly during crystallization of Earth's core, if it is oxygen-rich.

  16. Mercury, elemental

    Integrated Risk Information System (IRIS)

    Mercury , elemental ; CASRN 7439 - 97 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  17. Element Research.

    ERIC Educational Resources Information Center

    Herald, Christine

    2001-01-01

    Describes a research assignment for 8th grade students on the elements of the periodic table. Students use web-based resources and a chemistry handbook to gather information, construct concept maps, and present the findings to the full class using the mode of their choice: a humorous story, a slideshow or gameboard, a brochure, a song, or skit.…

  18. Element Research.

    ERIC Educational Resources Information Center

    Herald, Christine

    2001-01-01

    Describes a research assignment for 8th grade students on the elements of the periodic table. Students use web-based resources and a chemistry handbook to gather information, construct concept maps, and present the findings to the full class using the mode of their choice: a humorous story, a slideshow or gameboard, a brochure, a song, or skit.…

  19. Superheavy Elements

    NASA Astrophysics Data System (ADS)

    Hofmann, S.

    The nuclear shell model predicts that the next doubly magic shell closure beyond 208Pb is at a proton number Z=114, 120, or 126 and at a neutron number N=172 or 184. The outstanding aim of experimental investigations is the exploration of this region of spherical `SuperHeavy Elements' (SHEs). Experimental methods have been developed which allowed for the identification of new elements at production rates of one atom per month. Using cold fusion reactions which are based on lead and bismuth targets, relatively neutron-deficient isotopes of the elements from 107 to 113 were synthesized at GSI in Darmstadt, Germany, and/or at RIKEN in Wako, Japan. In hot fusion reactions of 48Ca projectiles with actinide targets more neutron-rich isotopes of the elements from 112 to 116 and even 118 were produced at the Flerov Laboratory of Nuclear Reactions (FLNR) at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. Recently, part of these data which represent the first identification of nuclei located on the predicted island of SHEs were confirmed in two independent experiments. The decay data reveal that for the heaviest elements, the dominant decay mode is α emission rather than fission. Decay properties as well as reaction cross-sections are compared with results of theoretical studies. Finally, plans are presented for the further development of the experimental set-up and the application of new techniques. At a higher sensitivity, the detailed exploration of the region of spherical SHEs will be in the center of interest of future experimental work. New data will certainly challenge theoretical studies on the mechanism of the synthesis, on the nuclear decay properties, and on the chemical behavior of these heaviest atoms at the limit of stability.

  20. FUEL ELEMENT

    DOEpatents

    Fortescue, P.; Zumwalt, L.R.

    1961-11-28

    A fuel element was developed for a gas cooled nuclear reactor. The element is constructed in the form of a compacted fuel slug including carbides of fissionable material in some cases with a breeder material carbide and a moderator which slug is disposed in a canning jacket of relatively impermeable moderator material. Such canned fuel slugs are disposed in an elongated shell of moderator having greater gas permeability than the canning material wherefore application of reduced pressure to the space therebetween causes gas diffusing through the exterior shell to sweep fission products from the system. Integral fission product traps and/or exterior traps as well as a fission product monitoring system may be employed therewith. (AEC)

  1. Lateral structuring and stability phenomena induced by block copolymers and core-shell nanogel particles at immiscible polymer/polymer interfaces

    NASA Astrophysics Data System (ADS)

    Gozen, Arif Omer

    We have investigated the parameters such as copolymer/nanoparticle concentration, architecture and molecular weight combined with film thickness, time and temperature in order to develop a molecular-level insight on how lateral interfacial structuring occurs at immiscible polymer/polymer interfaces. I order to develop a molecular-level understanding of how these 'smart' self-assembling materials and core-shell nanogel particles interact both intra- and inter-molecularly and form ordered structures in bulk, as well as at immiscible interfaces, we first focused on the response of core-shell polymer nanoparticles, designated CSNGs, composed of a cross-linked divinylbenzene core and poly(methyl methacrylate) (PMMA) arms as they segregate from PMMA homopolymer. We have demonstrated that these nanogel particles exhibit autophobic character when dispersed in high molecular weight homopolymer matrices and segregate to the interface with another fluid. We have further explored the migration of these new-generation nanogel particles (CSNG-Rs) segregating from PS homopolymer to PS/PMMA interfaces. Unlike the instability patterns observed with the CSNGs, which exhibit classical nucleation and growth mechanism with circular hole formation, we have observed an intriguing dewetting pattern and CSNG-Rs forming lateral aggregates and tentacle-like structures at the interface. In parallel with our core-shell particle studies, we have also explored the structuring of copolymer molecules that are far from equilibrium in bulk and complex laminate of polymer thin films. Our early triblock copolymer studies have proven that molecular asymmetry has a profound effect on order-disorder transition temperature. We focused primarily on the effect of the copolymer chemical composition (i.e., block sizes) on the dewetting behavior of PS/SM thin films on PMMA. We elucidate the interfacial segregation and concurrent micellization of diblock copolymers in a dynamically evolving environment with

  2. FUEL ELEMENT

    DOEpatents

    Howard, R.C.; Bokros, J.C.

    1962-03-01

    A fueled matrlx eontnwinlng uncomblned carbon is deslgned for use in graphlte-moderated gas-cooled reactors designed for operatlon at temperatures (about 1500 deg F) at which conventional metallic cladding would ordlnarily undergo undesired carburization or physical degeneratlon. - The invention comprlses, broadly a fuel body containlng uncombined earbon, clad with a nickel alloy contalning over about 28 percent by' weight copper in the preferred embodlment. Thls element ls supporirted in the passageways in close tolerance with the walls of unclad graphite moderator materlal. (AEC)

  3. Thin-finger growth and droplet pinch-off in miscible and immiscible displacements in a periodic network of microfluidic channels

    NASA Astrophysics Data System (ADS)

    Budek, Agnieszka; Garstecki, Piotr; Samborski, Adam; Szymczak, Piotr

    2015-11-01

    We report the results of experimental and numerical studies of two-phase flow in a periodic, rectangular network of microfluidic channels. This geometry promotes the formation of anisotropic, dendrite-like structures during viscous fingering experiments. The dendrites then compete with each other for the available flow, which leads to the appearance of hierarchical growth pattern. Combining experiments and numerical simulations, we analyze different growth regimes in such a system, depending on the network geometry and fluid properties. For immiscible fluids, a high degree of screening is present which results in a power-law distribution of finger lengths. Contrastingly, for miscible fluids, strong lateral currents of displaced fluid lead to the detachment of the heads of the longest fingers from their roots, thus preventing their further growth.

  4. Rapid isolation and purification of 1-cyano-2-hydroxy-3-butene (crambene) from Crambe abyssinica seed meal using immiscible solvent extraction and high-performance liquid chromatography.

    PubMed

    Niedoborski, T E; Klein, B P; Wallig, M A

    2001-08-01

    1-Cyano-2-hydroxy-3-butene (crambene) is a nitrile found in cruciferous vegetables that causes significant upregulation of quinone reductase and glutathione S-transferases in vivo and in vitro, making it a likely candidate as a cancer chemopreventive compound. To investigate further the putative anticarcinogenic mechanisms of crambene, a compound of the highest possible purity is vital. Therefore, a rapid and effective method of purification of crambene is necessary to continue studies of its beneficial health effects. A rapid method to isolate and purify natural crambene from either Crambe abyssinica (crambe) seed or commercially processed crambe seed meal was developed using immiscible solvent extraction followed by high-performance liquid chromatography. Use of this methodology eliminated the need for time-consuming and relatively inefficient column chromatography, improved extraction efficiency, and resulted in higher purity than previously used methodologies. Elimination of trace amounts of fatty acid residues, unachievable with previous methodologies, also was accomplished.

  5. Application of a novel oscillatory flow micro-bioreactor to the production of gamma-decalactone in a two immiscible liquid phase medium.

    PubMed

    Reis, N; Gonçalves, C N; Aguedo, M; Gomes, N; Teixeira, J A; Vicente, A A

    2006-04-01

    A novel micro-bioreactor based on the oscillatory flow technology was applied to the scale-down of the biotechnological production of gamma-decalactone. A decrease up to 50% of the time required to obtain the maximum concentration of the compound was observed, when compared with other scaled-down platforms (stirred tank bioreactor or shake flask). A three-fold increase in gamma-decalactone productivity was obtained by increasing oscillatory mixing intensity from Re(o) approximately 482 to Re(o) approximately 1447. This was presumably related to the effective contribution of the reactor geometry to enhanced mass transfer rates between the two immiscible liquid phases involved in the process by increasing the interfacial area.

  6. An experimental study to determine the relative influence of fluid-fluid interactions and media heterogeneities on the growth of immiscible viscous fingers

    SciTech Connect

    Stoelzel, D. M.

    1988-01-01

    The objective of this research is to evaluate the relative influence of transport media heterogeneities or fluid-fluid interactions on the formation of immiscible viscous fingers. Comparisons of experimental flows in a Hele-Shaw cell show that the spatial variations (heterogeneities) in the glass surface play a more significant role in finger growth than do random fluid-fluid instabilities. Visual records of over two hundred experimental runs were analyzed using digital video image processing and fractal dimension measurements. Digital overlays of the images show that finger patterns sweep essentially the same areas and have the same fractal dimension for different experimental conditions. This shows that heterogeneity in the flow regime is more significant in governing fluid displacements than the mobility controlled instabilities. 27 refs., 35 figs.

  7. Radiation effects on the immiscible polymer blend of nylon1010 and high-impact strength polystyrene (II): mechanical properties and morphology

    NASA Astrophysics Data System (ADS)

    Dong, Wenfei; Chen, Guangxin; Zhang, Wanxi

    2001-03-01

    The paper studies the morphology and mechanical properties of immiscible binary blends of the nylon 1010 and HIPS through the radiation crosslinking method. In this blend, the HIPS particles were the dispersed phases in the nylon1010 matrix. With increasing of dose, the elastic modulus increased. However, the tensile strength, elongation at break and the energy of fracture increased to a maximum at a dose of 0.34 MGy, then reduced with the increasing of dose. SEM photographs show that the hole sizes are not changed obviously at low dose and at high dose, remnants that cannot be dissolved in formic acid and THF can be observed in the holes and on the surface. TEM photographs showed that radiation destroys the rubber phases in the polymer blend.

  8. Experimental investigations and phase-field simulations of triple-phase-separation kinetics within liquid ternary Co-Cu-Pb immiscible alloys

    NASA Astrophysics Data System (ADS)

    Wu, Y. H.; Wang, W. L.; Yan, N.; Wei, B.

    2017-05-01

    The phase-separation kinetics and microstructure evolution mechanisms of liquid ternary C o43C u40P b17 immiscible alloys are investigated by both the drop tube technique and phase-field method. Two successive phase separations take place during droplet falling and lead to the formation of a three-phase three-layer core-shell structure composed of a Co-rich core, a Cu-rich middle layer, and a Pb-rich shell. The Pb-rich shell becomes more and more conspicuous as droplet diameter decreases. Meanwhile, the Co-rich core center gradually moves away from the core-shell center. Theoretical analyses show that a larger temperature gradient inside a smaller alloy droplet induces the accelerated growth of the surface segregation shell during triple-phase separation. The residual Stokes motion and the asymmetric Marangoni convection result in the appearance of an eccentric Co-rich core and the core deviation degree is closely related to the droplet size and initial velocity. A three-dimensional phase-field model of ternary immiscible alloys, which considers the successive phase separations under the combined effects of Marangoni convection and surface segregation, is proposed to explore the formation mechanisms of three-phase core-shell structures. The simulated core-shell morphologies are consistent with the experimental observations, which verifies the model's validity in reproducing the core-shell dynamic evolution. Numerical results reveal that the development of three-phase three-layer core-shell structures can be attributed to the primary and then secondary phase separations dominated simultaneously by Marangoni convection and surface segregation. Furthermore, the effects of droplet temperature gradient on the growth kinetics of the surface segregation shell are analyzed in the light of phase-field theory.

  9. Carbonatite-silicate immiscible melt inclusion in lamprophyre from Kutch, western India: Implication for plume-lithosphere interaction and initiation of Deccan Trap magmatism

    NASA Astrophysics Data System (ADS)

    Ray, Arijit; Paul, Dalim Kumar; Sen, Gautam; Biswas, Sanjib Kumar

    2014-05-01

    Kutch province of western India has undergone repeated rifting and marine transgression events from late Triassic to the late Cretaceous. Magmatic rocks occur in profusion in Kutch Basin. The southern part is characterized by occurrences of thick flows of tholeiitic basalt of Deccan Trap affinity, central part of Kutch Basin has numerous volcanic plugs of alkali basalt which is also considered as member of Deccan Trap, contain thin, discoidal mantle xenoliths of spinel lherzolite and wehrlite composition. Northern Kutch is dominated by suite of alkaline magmatic rocks similar to magmatic rocks of continental rift zone. The alkaline suite contains alkali pyroxenite, theralite, teschenite, basanite, nepheline syenite and kaersutite bearing lamprophyre (Ray et al., 2006, Das et al., 2007, Paul et al., 2008). The newly discovered east-west trending lamprophyre dyke swarm of northern Kutch (Pachham Island) is camptonite in composition and contains kaersutite phenocrysts in large proportion. These kaersutite phencrysts contain immscible melt/glass phases as melt inclusions. The lamprophyre yields an age of ca. 67 Ma.by Ar-Ar method (Sen et al., 2014 in press) synchronous with alkali basalt of central Kutch. The melt inclusions are fundamentally of two types - calciocarbonatite and alkaline silicate melts. We found sphene within carbonatitic melt and the rare mineral rhonite in silicate melt. Petrographic evidence indicates that carbonatite melt always occurs within alkali silicate melt as immiscible fraction. These carbonatite melts are extremely rich in CaCO3 (upto 95%) which contradicts the experimental results of carbonate melt composition (upto 80% CaCO3) in silicate-carbonate immiscible melt pair by Lee and Wyllie. The abundance of wehrlite xenoliths over lherzolite in alkali basalt, petrographic evidence of orthopyroxene to clinopyroxene transformation in wehrlite xenoliths, occurrence of calcite vein in mantle xenoliths indicate carbonatite metasomatism of spinel

  10. Phase characteristics of rare earth elements in metallic fuel for a sodium-cooled fast reactor by injection casting

    NASA Astrophysics Data System (ADS)

    Kuk, Seoung Woo; Kim, Ki Hwan; Kim, Jong Hwan; Song, Hoon; Oh, Seok Jin; Park, Jeong-Yong; Lee, Chan Bock; Youn, Young-Sang; Kim, Jong-Yun

    2017-04-01

    Uranium-zirconium-rare earth (U-Zr-RE) fuel slugs for a sodium-cooled fast reactor were manufactured using a modified injection casting method, and investigated with respect to their uniformity, distribution, composition, and phase behavior according to RE content. Nd, Ce, Pr, and La were chosen as four representative lanthanide elements because they are considered to be major RE components of fuel ingots after pyroprocessing. Immiscible layers were found on the top layers of the melt-residue commensurate with higher fuel slug RE content. Scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) data showed that RE elements in the melt-residue were distributed uniformly throughout the fuel slugs. RE element agglomeration did not contaminate the fuel slugs but strongly affected the RE content of the slugs.

  11. Influence of Viscous and Capillary Forces on Immiscible Fluid Displacement: Pore-Scale Experimental Study in a Water-Wet Micromodel Demonstrating Viscous and Capillary Fingering

    SciTech Connect

    Zhang, Changyong; Oostrom, Martinus; Wietsma, Thomas W.; Grate, Jay W.; Warner, Marvin G.

    2011-08-18

    Unstable immiscible fluid displacement in porous media affects geological carbon sequestration, enhanced oil recovery, and groundwater contamination by nonaqueous phase liquids. Characterization of immiscible displacement processes at the pore-scale is important to better understand macroscopic processes at the continuum-scale. A series of displacement experiments was conducted to investigate the impacts of viscous and capillary forces on displacement stability and fluid saturation distributions in a homogeneous water-wet pore network micromodel with precisely-microfabricated pore structures. Displacements were studied using seven wetting-nonwetting fluid pairs with viscosity ratios M (viscosity of the advancing nonwetting fluid divided by the viscosity of the displaced wetting fluid) ranging four orders of magnitude from logM = -1.95 to 1.88. The micromodel was initially saturated with either polyethylene glycol 200 (PEG200) or water as a wetting fluid, which was then displaced by a nonwetting alkane fluid under different flow rates. Capillary numbers (Ca) ranged over four orders of magnitude for the reported experiments, from logCa = -5.88 to -1.02. Fluorescent microscopy was used to visualize displacement and measure nonwetting fluid saturation distributions. These experiments extend the classical work by Lenormand et al. by using water-wet micromodels, high-precision fabrication, and enhanced image analysis of the saturation distributions. In the micromodel experiments initially saturated with PEG200, a viscous wetting fluid, unstable displacement occurred by viscous fingering over the whole range of imposed capillary numbers. For the experiments initially saturated with water, unstable displacement occurred by capillary fingering at low capillary numbers. When the viscous forces were increased by increasing the injection rate, crossover into stable displacement was observed for the fluid pairs with M > 0. For unstable displacement experiments applying the same

  12. Generalized three-dimensional lattice Boltzmann color-gradient method for immiscible two-phase pore-scale imbibition and drainage in porous media

    NASA Astrophysics Data System (ADS)

    Leclaire, Sébastien; Parmigiani, Andrea; Malaspinas, Orestis; Chopard, Bastien; Latt, Jonas

    2017-03-01

    This article presents a three-dimensional numerical framework for the simulation of fluid-fluid immiscible compounds in complex geometries, based on the multiple-relaxation-time lattice Boltzmann method to model the fluid dynamics and the color-gradient approach to model multicomponent flow interaction. New lattice weights for the lattices D3Q15, D3Q19, and D3Q27 that improve the Galilean invariance of the color-gradient model as well as for modeling the interfacial tension are derived and provided in the Appendix. The presented method proposes in particular an approach to model the interaction between the fluid compound and the solid, and to maintain a precise contact angle between the two-component interface and the wall. Contrarily to previous approaches proposed in the literature, this method yields accurate solutions even in complex geometries and does not suffer from numerical artifacts like nonphysical mass transfer along the solid wall, which is crucial for modeling imbibition-type problems. The article also proposes an approach to model inflow and outflow boundaries with the color-gradient method by generalizing the regularized boundary conditions. The numerical framework is first validated for three-dimensional (3D) stationary state (Jurin's law) and time-dependent (Washburn's law and capillary waves) problems. Then, the usefulness of the method for practical problems of pore-scale flow imbibition and drainage in porous media is demonstrated. Through the simulation of nonwetting displacement in two-dimensional random porous media networks, we show that the model properly reproduces three main invasion regimes (stable displacement, capillary fingering, and viscous fingering) as well as the saturating zone transition between these regimes. Finally, the ability to simulate immiscible two-component flow imbibition and drainage is validated, with excellent results, by numerical simulations in a Berea sandstone, a frequently used benchmark case used in this

  13. Age, petrology and geochemistry of carbonate-dykes and related clinopyroxenite xenoliths from the Ivrea-Verbano Zone (Italy/Switzerland): evidence of Jurassic carbonatite formation by liquid immiscibility

    NASA Astrophysics Data System (ADS)

    Galli, Andrea; Grassi, Daniele; Sartori, Gino

    2017-04-01

    In the Ivrea-Verbano Zone (IVZ, Italy/Switzerland) the deepest portion of the continental crust is exposed. Its geological evolution has been largely controlled by both Permian underplating of mantle-derived basic magmas and Mesozoic alkaline intrusions into the high-grade basement of the Southern Alps. Widespread in the IVZ, up to 40 m thick, zircon-bearing carbonate-dykes occur. The dykes are mostly composed of calcite with subordinate clinopyroxene and amphibole, show sharp intrusive contacts to the host rocks and typically contain rounded or angular, up to 2 meter large phlogopite-amphibole-apatite-rutile-ilmenite ± garnet, corundum or spinel clinopyroxenite xenoliths. Carbonate-dykes shows an enrichment of LREE over HREE ((La/Yb)N = 14), with a Σ REE = 95-115 ppm and Y/Ho = 26-33. On the chondrite-normalized REE abundances diagram, no Eu anomaly is observed. Mantle-normalized pattern shows strong negative anomalies at Cs, Rb, K, Pb, P, Zr, Hf and Ti and positive Ba, Th, Sr, Nd anomalies, similarly to the "world average carbonatite" composition. Measured absolute trace element concentrations are lower than average carbonatites but significantly higher than limestones and similar to typical cumulate carbonatites. Grt-bearing clinopyroxenite enclave have a XMg of 0.50, K2O + Na2O of 1.01 and are rich in TiO2 (3.40 wt%) and P2O5 (0.93 wt%). Grt-free clinopyroxenites show higher XMg values of 0.61-0.73 and are alkali, TiO2 and P2O5 poorer (K2O + Na2O of 0.21-0.59 wt%, TiO2 of 1.16-2.72 wt% and P2O5 < 0.20 wt%). On the mantle-normalized trace element diagram, the enclave display a nearly antithetic pattern in respect to the enclosing carbonates, with positive anomalies at Cs, Rb, U, Pb, Zr, Hf, Ti and negative anomalies at Ba, Th, Sr and Nd. Melt composition calculated from carbonate composition using partitioning coefficients between carbonatite and silicate melts reproduces the trace element patterns displayed by the pyroxenite xenoliths. This suggests that

  14. Immiscible phase filter extraction and equivalent amplification of genotypes 1-6 of hepatitis C RNA: The building blocks for point-of-care diagnosis.

    PubMed

    Neto, Mário F; Butzler, Matthew A; Reed, Jennifer L; Rui, Xiang; Fisher, Mark J; Kelso, David M; McFall, Sally M

    2017-10-01

    The lack of hepatitis C virus (HCV) diagnostic tests designed for use in decentralized settings is a major obstacle for providing access to treatment and prevention services particularly in low and middle income countries. Here we describe the development and validation of two building blocks of the HCV Quant Assay, a test in development for point-of-care use: 1) an RT-qPCR assay with noncompetitive internal control that equivalently detects the 6 major HCV genotypes and 2) an automated sample prep method using immiscible phase filter technology. This novel assay has wide dynamic range of HCV quantification and a limit of detection of 30IU/ml with 200μl specimen volume. In a preliminary study of 61 clinical specimens, the HCV Quant Assay demonstrated 100% sensitivity and specificity and gave comparable viral load results across 4 logs of IU/ml when compared to the Abbott RealTime HCV Assay. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Eutectic, monotectic and immiscibility systems of nimesulide with water-soluble carriers: phase equilibria, solid-state characterisation and in-vivo/pharmacodynamic evaluation.

    PubMed

    Abdelkader, Hamdy; Abdallah, Ossama Y; Salem, Hesham; Alani, Adam W G; Alany, Raid G

    2014-10-01

    The solid-state interactions of fused mixtures nimesulide (ND) with polyethylene glycol (PEG) 4000, urea or mannitol were studied through constructing thaw-melt phase equilibrium diagrams. The solid-state characteristics were investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Various types of interactions were identified such as the formation of a eutectic system of ND-PEG 4000, monotectic system of ND-urea and complete solid immiscibility of ND with mannitol. The effects of carrier concentrations on the equilibrium solubility and in-vitro dissolution characteristics were studied. Linear increases (R(2)  > 0.99) in the aqueous solubility of ND in various concentrations of PEG 4000 and urea were obtained, whereas mannitol did not exhibit any effect on the solubility of ND. Similar trends were obtained with the dissolution efficiency of the fused mixtures of ND with PEG 4000 and urea compared with the corresponding physical mixtures and untreated drug. The analgesic effects of untreated ND and the selected formulations were investigated by evaluating the drug's ability to inhibit the acetic acid-induced writhing response. The analgesic effect of ND in a eutectic mixture with PEG 4000 and a monotectic mixture with urea was potentiated by 3.2 and 2.7-fold respectively compared with the untreated drug. © 2014 Royal Pharmaceutical Society.

  16. Multiscale level-set method for accurate modeling of two-phase immiscible flow with deposited thin-films on solid surfaces

    NASA Astrophysics Data System (ADS)

    Abu Alsaud, Motaz; Riaz, Amir; Tchelepi, Hamdi; University of Maryland, College Park Collaboration; Stanford University Team

    2016-11-01

    We developed a multiscale sharp interface method based on the level-set for two-phase immiscible flow with pre-existing thin-films on solid surfaces. The lubrication approximation theory is used to model the thin- film equation efficiently. The incompressible Navier-Stokes, level-set, and thin-film evolution equation are coupled sequentially to capture the physics occurring at multiple length scales. The proposed multiscale method is validated through comparison with the augmented Young-Laplace equation that includes the Van der Waals intermolecular force for a static meniscus in a capillary tube. The viscous bending in the advancing interface over precursor film problem is captured by the numerical method and agrees with the Cox-Voinov theory. The problem of a moving-bubble inside a capillary tube is modeled, and the results compare well with both theory and experiments. In addition, the performance of the new approach is assessed by studying the spurious currents for capillary-dominated flows at low capillary numbers. The method is applicable for flows with a capillary number as low as Ca =10-6 .

  17. Liquid-Phase Synthesis of Ba2V2O7 Phosphor Powders and Films Using Immiscible Biphasic Organic-Aqueous Systems.

    PubMed

    Takahashi, Mami; Hagiwara, Manabu; Fujihara, Shinobu

    2016-08-15

    A liquid-phase synthesis of inorganic phosphor materials at a moderate temperature was proposed by using immiscible liquid-liquid biphasic systems. A self-activated Ba2V2O7 phosphor was actually synthesized from vanadium alkoxide dissolved in an organic solution and barium acetate in an aqueous solution. A mild hydrolysis reaction of the alkoxide started at the organic-inorganic interface, and an intermediate compound, Ba(VO3)2·H2O, was initially formed. Ba2V2O7 powders were then obtained by the conversion from Ba(VO3)2·H2O promoted in the aqueous solution. Ba2V2O7 films were obtained on surface-modified silica glass substrates through the similar chemical reactions. Factors such as the surface state of substrates, the kind of organic solvents, and the volume of aqueous solutions were examined to improve the film deposition behavior. The resultant Ba2V2O7 materials showed broad-band visible photoluminescence upon irradiation with ultraviolet light based on the charge transfer transition in the VO4(3-) units existing as dimers.

  18. Liquid carry-over in an injection moulded all-polymer chip system for immiscible phase magnetic bead-based solid-phase extraction

    NASA Astrophysics Data System (ADS)

    Kistrup, Kasper; Skotte Sørensen, Karen; Wolff, Anders; Fougt Hansen, Mikkel

    2015-04-01

    We present an all-polymer, single-use microfluidic chip system produced by injection moulding and bonded by ultrasonic welding. Both techniques are compatible with low-cost industrial mass-production. The chip is produced for magnetic bead-based solid-phase extraction facilitated by immiscible phase filtration and features passive liquid filling and magnetic bead manipulation using an external magnet. In this work, we determine the system compatibility with various surfactants. Moreover, we quantify the volume of liquid co-transported with magnetic bead clusters from Milli-Q water or a lysis-binding buffer for nucleic acid extraction (0.1 (v/v)% Triton X-100 in 5 M guanidine hydrochloride). A linear relationship was found between the liquid carry-over and mass of magnetic beads used. Interestingly, similar average carry-overs of 1.74(8) nL/μg and 1.72(14) nL/μg were found for Milli-Q water and lysis-binding buffer, respectively.

  19. Compatibilization of immiscible poly(lactic acid)/poly(ɛ-caprolactone) blend through electron-beam irradiation with the addition of a compatibilizing agent

    NASA Astrophysics Data System (ADS)

    Shin, Boo Young; Han, Do Hung

    2013-02-01

    The aim of this study was to compatibilize immiscible poly(lactic acid) (PLA)/poly(ɛ-caprolactone) (PCL) blend by using electron-beam radiation method with the addition of a compatibilizing agent. Glycidyl methacrylate (GMA) was chosen as the compatibilizing agent, in the expectation that the GMA plays a role as a monomeric compatibilizer and a reactive agent at the interface between the PLA and the PCL phases. Compatibilization process has been investigated through the melt mixing of the PLA/PCL and the GMA by using a twin-screw extruder and the exposure of the PLA/PCL/GMA mixture to electron-beam radiation at room temperature. The melt mixing process was performed to locate the GMA at the interface, thereby expecting a finer morphology due to the GMA as the monomeric plasticizer. The exposure process was carried out to induce definite interfacial adhesion at the interface through electron-beam initiated cross-copolymerization by the medium of the GMA as the reactive agent. To investigate the results of this compatibilization strategy, the morphological, mechanical, and rheological properties of the blend were analyzed. The morphological study clearly showed the reduced particle size of dispersed PCL domains and significantly improved interfacial adhesion by the electron-beam irradiation with the addition of the GMA. The stress-strain curves of the blends irradiated at less than 20 kGy showed the typical characteristics of ductile materials. The tensile properties of the blend were strongly affected by the dose of irradiation.

  20. Molecular dynamics study of solubilization of immiscible solutes by a micelle: Free energy of transfer of alkanes from water to the micelle core by thermodynamic integration method

    NASA Astrophysics Data System (ADS)

    Fujimoto, K.; Yoshii, N.; Okazaki, S.

    2010-08-01

    Free energy of transfer, ΔGw→m, from water phase to a sodium dodecyl sulfate (SDS) micelle core has been calculated for a series of hydrophobic solutes originally immiscible with water by thermodynamic integration method combined with molecular dynamics calculations. The calculated free energy of transfer is in good correspondence to the experiment as well as the theoretical free energy of transfer. The calculated ΔGw→m's are all negative, implying that the alkane molecules are more stable in the micelle than in the water phase. It decreases almost linearly as a function of the number of carbon atoms of the alkanes longer than methane with a decrement of 3.3 kJ mol-1 per one methylene group. The calculated free energy of transfer indicates that, for example, at the micelle concentration of 50 CMC (critical micelle concentration), about only 1 of 6 micelles or 1 of 32 000 micelles does not contain a solute methane or n-octane molecule, respectively.

  1. Computational modeling technique for numerical simulation of immiscible two-phase flow problems involving flow and transport phenomena in porous media with hysteresis

    NASA Astrophysics Data System (ADS)

    Abreu, Eduardo; Lambert, Wanderson

    2012-05-01

    Numerical methods are necessary, and are extremely important, in developing an understanding of the dynamics of multiphase flow of fluids in porous media applications to maximize hydrocarbon recovery as well as to simulate contaminant transport of soluble or insoluble species in groundwater contamination problems. This work deals with a problem very common in water-flooding process in petroleum reservoir to motivate the proposed modeling: the flow of two immiscible and incompressible fluid phases. The system of equations which describe this type of flow is a coupled, highly nonlinear system of time-dependent partial differential equations. The equation for the invading fluid (e.g., water phase) is a convection-dominated, degenerate parabolic partial differential equation whose solutions typically exhibit sharp moving fronts (e.g., moving internal layers with strong gradients) and it is very difficult to approximate numerically. We propose a two-stage numerical method to describe the injection problem for a model of two-phase (water-oil) flow in a porous rock, taking into account both gravity and hysteresis effects for solving transport flow problems in porous media. Indeed, we also investigate the Riemann problem for the one-dimensional, purely hyperbolic system, associated to the full differential model problem at hand. Thus, the use of accurate numerical methods in conjunction with one-dimensional semi-analytical Riemann solutions might provide valuable insight into the qualitative solution behavior of the full nonlinear governing flow system.

  2. Interface dynamics of immiscible two-phase lattice-gas cellular automata: a model with random dynamic scatterers and quenched disorder in two dimensions.

    PubMed

    Azevedo, R M; Montenegro-Filho, R R; Coutinho-Filho, M D

    2013-09-01

    We use a lattice gas cellular automata model in the presence of random dynamic scattering sites and quenched disorder in the two-phase immiscible model with the aim of producing an interface dynamics similar to that observed in Hele-Shaw cells. The dynamics of the interface is studied as one fluid displaces the other in a clean lattice and in a lattice with quenched disorder. For the clean system, if the fluid with a lower viscosity displaces the other, we show that the model exhibits the Saffman-Taylor instability phenomenon, whose features are in very good agreement with those observed in real (viscous) fluids. In the system with quenched disorder, we obtain estimates for the growth and roughening exponents of the interface width in two cases: viscosity-matched fluids and the case of unstable interface. The first case is shown to be in the same universality class of the random deposition model with surface relaxation. Moreover, while the early-time dynamics of the interface behaves similarly, viscous fingers develop in the second case with the subsequent production of bubbles in the context of a complex dynamics. We also identify the Hurst exponent of the subdiffusive fractional Brownian motion associated with the interface, from which we derive its fractal dimension and the universality classes related to a percolation process.

  3. Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

    NASA Technical Reports Server (NTRS)

    Bansal, N. P.

    1992-01-01

    Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

  4. Thin film fabrication of PMMA/MEH-PPV immiscible blends by corona discharge coating and its application to polymer light emitting diodes.

    PubMed

    Jung, Hee Joon; Park, Youn Jung; Choi, Sang Hun; Hong, Jae-Min; Huh, June; Cho, Jun Han; Kim, Jung Hyun; Park, Cheolmin

    2007-02-13

    We introduce a new and facile process, corona discharge coating (CDC), to fabricate thin polymer films of the immiscible poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and poly(methyl methacrylate) (PMMA) blends. The method is based on utilizing directional electric flow, known as electric wind, of the charged unipolar particles generated by corona discharge between a metallic needle and a bottom plate under high electric field (5-10 kV/cm). The electric flow rapidly spreads out the polymer solution on the bottom plate and subsequently forms a smooth and flat thin film over a large area within a few seconds. The method is found to be effective for fabricating uniform thin polymer films with areas larger than approximately 30 mm2. The thin films obtained by CDC exhibit unique microstructures where well-defined spherical and cylindrical domains of approximately 50 nm in diameter coexist. These nanosized domains are found to be much smaller than those in films made by conventional spin coating, which suggests that CDC is beneficial for fabricating phase-separated thin film structures with significantly increased interfacial areas. The effects of the applied voltage, tip-to-plate distance, and substrates on the film formation as well as the resulting microstructure are investigated. Furthermore, the light emitting performance of a device prepared by CDC is compared with one made by spin coating.

  5. Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by sol-gel process

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1990-01-01

    Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water:TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, x ray diffraction, surface area and pore size distribution measurements.

  6. Insights into the role of wettability in cathode catalyst layer of proton exchange membrane fuel cell; pore scale immiscible flow and transport processes

    NASA Astrophysics Data System (ADS)

    Fathi, H.; Raoof, A.; Mansouri, S. H.

    2017-05-01

    The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of CCL agglomerates due to the electrochemical reactions, water spatial distribution affects transport of oxygen through the CCL as well as the rate of reaction at the agglomerate surfaces. To explore the wettability effects, we apply hydrophilic and hydrophobic properties using different surface contact angles. Effective diffusivity is calculated under several water saturation levels. Results indicate larger diffusive transport values for hydrophilic domain compared to the hydrophobic media where the liquid water preferentially floods the larger pores. However, hydrophobic domain showed more available surface area and higher oxygen consumption rate at the reaction sites under various saturation levels, which is explained by the effect of wettability on pore-scale distribution of water. Hydrophobic domain, with a contact angle of 150, reveals efficient water removal where only 28% of the pore space stays saturated. This condition contributes to the enhanced available reaction surface area and oxygen diffusivity.

  7. Multiscale level-set method for accurate modeling of two-phase immiscible flow with deposited thin-films on solid surfaces

    NASA Astrophysics Data System (ADS)

    Abu AlSaud, M.; Riaz, A.; Tchelepi, H.

    2016-12-01

    We developed a multiscale sharp interface method based on the level-set for two-phase immiscible flow with pre-existing thin-films on solid surfaces. The lubrication approximation theory is used to model the thin-film equation efficiently. The incompressible Navier-Stokes, level-set, and thin-film evolution equation are coupled sequentially to capture the physics occurring at multiple length scales. The proposed multiscale method is validated through comparison with the augmented Young-Laplace equation that includes the Van der Waals intermolecular force for a static meniscus in a capillary tube. The viscous bending in the advancing interface over precursor film problem is captured by the numerical method and agrees with the Cox-Voinov theory. The problem of a moving-bubble inside a capillary tube is modeled, and the results compare well with both theory and experiments. In addition, the performance of the new approach is assessed by studying the spurious currents for capillary-dominated flows at low capillary numbers. The method is applicable for flows with a capillary number as low as Ca10-6.

  8. Low temperature synthesis of CaO-SiO2 glasses having stable liquid-liquid immiscibility by the sol-gel process

    NASA Technical Reports Server (NTRS)

    Bansal, N. P.

    1992-01-01

    Calcium silicate glass compositions lying within the liquid-liquid immiscibility dome of the phase diagram, which could not have been prepared by the conventional melting method, were synthesized by the sol-gel process. Hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) solutions containing up to 20 mol percent calcium nitrate resulted in the formation of clear and transparent gels. The gel formation time decreased with increase in water: TEOS mole ratio, calcium content, and the reaction temperature. Smaller values of gel times in the presence of calcium nitrate are probably caused by lowering of the ionic charge on the sol particles by the salt present. The gelation activation energy, E(sub gel), was evaluated from temperature dependence of the gel time. Presence of Ca(2+) ions or the water:TEOS mole ratio did not have an appreciable effect on the value of E(sub gel). Presence of glycerol in the solution helped in the formation of crack-free monolithic gel specimens. Chemical and structural changes occurring in the gels, as a function of the heat treatments, have been monitored using DTA, TGA, IR-spectroscopy, X-ray diffraction, surface area and pore size distribution measurements.

  9. Electron beam irradiation induced compatibilization of immiscible polyethylene/ethylene vinyl acetate (PE/EVA) blends: Mechanical properties and morphology stability

    NASA Astrophysics Data System (ADS)

    Entezam, Mehdi; Aghjeh, Mir Karim Razavi; Ghaffari, Mehdi

    2017-02-01

    Gel content, mechanical properties and morphology of immiscible PE/EVA blends irradiated by high energy electron beam were studied. The results of gel content measurements showed that the capability of cross-linking of the blend samples increased with an increase of the EVA composition. Also, the gel content for most compositions of the blends displayed a positive deviation from the additive rule. The results of mechanical properties showed that the tensile strength and elongation at break of the samples increased and decreased, respectively, with irradiation dose. On the other hand, the mechanical properties of the irradiated blends also depicted a positive deviation from additive rule contrary to the un-irradiated blends. A synergistic effect observed for the mechanical properties improvement of the irradiated blends and it was attributed to the probable formation of the PE-graft-EVA copolymers at the interface of the blends during the irradiation process. A theoretical analysis revealed that irradiation induced synergistic effect was more significant for EVA-rich blends with weaker interfacial interaction as compared to PE-rich blends. The morphological analysis indicated that the blend morphology was not affected obviously, whereas it was stabilized by irradiation.

  10. Interface dynamics of immiscible two-phase lattice-gas cellular automata: A model with random dynamic scatterers and quenched disorder in two dimensions

    NASA Astrophysics Data System (ADS)

    Azevedo, R. M.; Montenegro-Filho, R. R.; Coutinho-Filho, M. D.

    2013-09-01

    We use a lattice gas cellular automata model in the presence of random dynamic scattering sites and quenched disorder in the two-phase immiscible model with the aim of producing an interface dynamics similar to that observed in Hele-Shaw cells. The dynamics of the interface is studied as one fluid displaces the other in a clean lattice and in a lattice with quenched disorder. For the clean system, if the fluid with a lower viscosity displaces the other, we show that the model exhibits the Saffman-Taylor instability phenomenon, whose features are in very good agreement with those observed in real (viscous) fluids. In the system with quenched disorder, we obtain estimates for the growth and roughening exponents of the interface width in two cases: viscosity-matched fluids and the case of unstable interface. The first case is shown to be in the same universality class of the random deposition model with surface relaxation. Moreover, while the early-time dynamics of the interface behaves similarly, viscous fingers develop in the second case with the subsequent production of bubbles in the context of a complex dynamics. We also identify the Hurst exponent of the subdiffusive fractional Brownian motion associated with the interface, from which we derive its fractal dimension and the universality classes related to a percolation process.

  11. Rolling-Element Bearings

    NASA Technical Reports Server (NTRS)

    Hamrock, B. J.; Anderson, W. J.

    1983-01-01

    Rolling element bearings are a precision, yet simple, machine element of great utility. A brief history of rolling element bearings is reviewed and the type of rolling element bearings, their geometry and kinematics, as well as the materials they are made from and the manufacturing processes they involve are described. Unloaded and unlubricated rolling element bearings, loaded but unlubricated rolling element bearings and loaded and lubricated rolling element bearings are considered. The recognition and understanding of elastohydrodynamic lubrication covered, represents one of the major development in rolling element bearings.

  12. One-step synthesis of layered yttrium hydroxides in immiscible liquid–liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

    SciTech Connect

    Watanabe, Mebae; Fujihara, Shinobu

    2014-02-15

    Inorganic–organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid–liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu{sup 3+} ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect. - Graphical abstract: The Eu{sup 3+}-doped layered yttrium hydroxide exhibits intense red photoluminescence after intercalation of benzoate ions. Display Omitted - Highlights: • Immiscible biphasic liquid systems were introduced to synthesize layered yttrium hydroxides. • The temperature of the biphasic systems does not exceed 80 °C in one step of the synthesis. • Hydrophobic organic anions were intercalated between the hydroxide layers in one pot. • Structure and morphology of the hydroxides were modulated by changing the kind of organic anions. • Eu{sup 3+}-doping led to red luminescence from the hydroxides in association with the intercalated organic anions.

  13. Comparison of Interfacial Partitioning Tracer Test and X-ray Microtomography Measurements of Immiscible Fluid-Fluid Interfacial Areas within the Identical System

    NASA Astrophysics Data System (ADS)

    Carroll, K. C.; McDonald, K.; Brusseau, M. L. L.

    2015-12-01

    The interfacial area between immiscible fluids in porous media has been demonstrated to be a critical entity for improved understanding, characterization, and simulation of multiphase flow and mass transport in the subsurface. Two general methods are available for measuring interfacial areas for 3-D porous-media systems, high-resolution microtomographic imaging and interfacial partitioning tracer tests (IPTT). Each method has their associated advantages and disadvantages. A few prior research efforts have conducted comparative analyses of the two methods, which have generally indicated disparities in measured values for natural geomedia. For these studies, however, interfacial areas were measured for separate samples with each method due to method restrictions. Thus, to date, there has been no comparative analysis conducted wherein the two measurement methods were applied to the exact same sample. To address this issue, trichloroethene-water interfacial areas were measured for a system comprising a well-sorted, natural sand (median grain diameter of 0.323 mm) using both X-ray microtomography and IPTTs. The microtomographic imaging was conducted on the same packed columns used to conduct the IPTTs. Columns were imaged before and after the IPTTs to evaluate potential impacts of the tracer tests on fluid configuration. The interfacial areas measured using IPTT were 4-6 times larger than the microtomography results, which is consistent with previous work. This disparity was attributed to the inability of the microtomography method to characterize interfacial area associated with microscopic surface roughness. The results indicate that both methods provide useful measures of interfacial area as long as their limitations are recognized.

  14. Immiscible displacement of oil by water in a microchannel: asymmetric flow behavior and nonlinear stability analysis of core-annular flow.

    PubMed

    Foroughi, Hooman; Abbasi, Alireza; Das, Kausik S; Kawaji, Masahiro

    2012-02-01

    The immiscible displacement of oil by water in a circular microchannel was investigated. A fused silica microchannel with an inner diameter of 250 μm and a length of 7 cm was initially filled with a viscous silicone oil. Only water then was injected into the channel. We describe our flow observations based on the two-dimensional images captured in the middle of the channel. The water finger displaced the oil and left an oil film on the channel wall. While the oil was being displaced at the core, the flow resistance decreased, which resulted in increases in water flow rate and inertia. Eventually, the water finger reached the channel exit and formed a core-annular flow pattern. The wavelength of the waves formed at the oil-water interface also increased with the increase in inertia. The initially symmetric interfacial waves became asymmetric with time. Also, the water core shifted from the center of the channel and left a thinner oil film on one side of the microchannel. Under all flow rates tested in this study, as long as the water was continuously injected, the water core was stable and no breakup into droplets was observed. We also discuss the flow stability based on nonlinear and linear stability analyses performed on the core-annular flow. Compared to the linear analysis, which ignores the inertia effects, the nonlinear analysis, which includes the inertia effects, predicts longer interfacial wavelengths by a factor of 1/sqrt[1-a(o)/2(We(w) + We(o)a(o)(2)/1-a(o)(2))] where We(w) and We(o) are the Weber numbers of the water and the oil phases, respectively, and a(o) is the unperturbed water core radius made dimensionless by the channel radius.

  15. Application of Proper Orthogonal Decomposition to the morphological analysis of confined co-axial jets of immiscible liquids with comparable densities

    NASA Astrophysics Data System (ADS)

    Charalampous, Georgios; Hardalupas, Yannis

    2014-11-01

    The development of a round liquid jet under the influence of a confined coaxial flow of an immiscible liquid of comparable density (central to annular flow density ratio of 8:10) was investigated in the vicinity of the nozzle exit. Two flow regimes were considered; one where the annular flow is faster than the central jet, so the central liquid jet is accelerated and one where the annular flow is slower, so the central liquid jet is decelerated. The central jet was visualised by high speed photography. Three modes of jet development were identified and classified in terms of the Reynolds number, Re, of the central jet which was in the range of 525 < Re < 2725, a modified definition of the Weber number, We, which allows the distinction between accelerating and deceleration flows and was in the range of -22 < We < 67 and the annular to central Momentum Ratio, MR, of the two streams which was in the range of 3.6 < MR < 91. By processing the time resolved jet images using Proper Orthogonal Decomposition (POD), it was possible to reduce the description of jet morphology to a small number of spatial modes, which isolated the most significant morphologies of the jet development. In this way, the temporal and spatial characteristics of the instabilities on the interface were clearly identified which highlights the advantages of POD over direct observation of the images. Relationships between the flow parameters and the interfacial waves were established. The wavelength of the interfacial instability was found to depend on the velocity of the fastest moving stream, which is contrary to findings for fluids with large density differences.

  16. Amorphous phase formation, spinodal decomposition, and fractal growth of nanocrystals in an immiscible Hf-Nb system studied by ion beam mixing and atomistic modeling

    SciTech Connect

    Tai, K. P.; He, X.; Liu, B. X.

    2008-04-15

    In the equilibrium immiscible Hf-Nb system characterized by a positive heat of formation, five Hf-Nb metallic glasses with overall compositions of Hf{sub 84}Nb{sub 16}, Hf{sub 65}Nb{sub 35}, Hf{sub 45}Nb{sub 55}, Hf{sub 38}Nb{sub 62}, and Hf{sub 20}Nb{sub 80} are obtained by ion beam mixing with properly designed Hf-Nb multilayered films, suggesting a glass-forming composition range of 16-80 at. % of Nb. For the special case of Hf{sub 45}Nb{sub 55} located at the ridge point on the convex free energy curve, dual-glass phases are formed at a dose of 2x10{sup 15} Xe{sup +}/cm{sup 2}, which results from a spinodal decomposition of the expected Hf{sub 45}Nb{sub 55} amorphous phase. With increasing irradiation dose, fractal growth of nanocrystals (around 20 nm) appears in the major glass phase and the dimension is determined to be from 1.70 to 1.84 within a dose range of (4-7)x10{sup 15} Xe{sup +}/cm{sup 2}. In atomistic modeling, a n-body Hf-Nb potential is first constructed with the aid of ab initio calculations. Applying the constructed potential, molecular dynamics simulations using the hcp and bcc solid solution models, reveals an intrinsic glass-forming range to be within 15-83 at. % of Nb, which is compatible with the ion beam mixing experiments. Moreover, the formation of the metallic glasses and the fractal growth in association with the amorphous spinodal decomposition are also discussed in terms of the atomic collision theory and cluster-diffusion-limited-aggregation model.

  17. Development of a microfluidic-chip system for liquid-phase microextraction based on two immiscible organic solvents for the extraction and preconcentration of some hormonal drugs.

    PubMed

    Asl, Yousef Abdossalami; Yamini, Yadollah; Seidi, Shahram

    2016-11-01

    In the present study, for the first time, an on-chip liquid phase microextraction (LPME) coupled with high performance liquid chromatography was introduced for the analysis of levonorgestrel (Levo), dydrogesterone (Dydo) and medroxyprogesterone (Medo) as the model analytes in biological samples. The chip-based LPME set-up was composed of two polymethyl methacrylate (PMMA) plates with microfabricated channels and a microporous membrane sandwiched between them to separate the sample solution and acceptor phase. These channels were used as a flow path for the sample solution and a thin compartment for the acceptor phase, respectively. In this system, two immiscible organic solvents were used as supported liquid membrane (SLM) and acceptor phase, respectively. During extraction, the model analytes in the sample solution were transported through the SLM (n-dodecane) into the acceptor organic solvent (methanol). The new set-up provided effective and reproducible extractions using low volumes of the sample solution. The effective parameters on the extraction efficiency of the model analytes were optimized using one variable at a time method. Under the optimized conditions, the new set-up provided good linearity in the range of 5.0-500µgL(-1) for the model analytes with the coefficients of determination (r(2)) higher than 0.9909. The relative standard deviations (RSDs%) and limits of detection (LODs) values were less than 6.5% (n=5) and 5.0µgL(-1), respectively. The preconcentration factors (PFs) were obtained using 1.0mL of the sample solution and 20.0µL of the acceptor solution higher than 19.9-fold. Finally, the proposed method was successfully applied for the extraction and determination of the model analytes in urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Discrete Element Modeling

    SciTech Connect

    Morris, J; Johnson, S

    2007-12-03

    The Distinct Element Method (also frequently referred to as the Discrete Element Method) (DEM) is a Lagrangian numerical technique where the computational domain consists of discrete solid elements which interact via compliant contacts. This can be contrasted with Finite Element Methods where the computational domain is assumed to represent a continuum (although many modern implementations of the FEM can accommodate some Distinct Element capabilities). Often the terms Discrete Element Method and Distinct Element Method are used interchangeably in the literature, although Cundall and Hart (1992) suggested that Discrete Element Methods should be a more inclusive term covering Distinct Element Methods, Displacement Discontinuity Analysis and Modal Methods. In this work, DEM specifically refers to the Distinct Element Method, where the discrete elements interact via compliant contacts, in contrast with Displacement Discontinuity Analysis where the contacts are rigid and all compliance is taken up by the adjacent intact material.

  19. Elements of Film.

    ERIC Educational Resources Information Center

    Bobker, Lee R.

    A film is the successful combination of two distinct groups of elements: (1) the technical elements by which the film is made (camera, lighting, sound and editing) and (2) the esthetic elements that transform the craft into an art. This book attempts to combine the study of these elements by providing technical information about the process of…

  20. Organic Elemental Analysis.

    ERIC Educational Resources Information Center

    Ma, T. S.; Wang, C. Y.

    1984-01-01

    Presents a literature review on methods used to analyze organic elements. Topic areas include methods for: (1) analyzing carbon, hydrogen, and nitrogen; (2) analyzing oxygen, sulfur, and halogens; (3) analyzing other elements; (4) simultaneously determining several elements; and (5) determing trace elements. (JN)

  1. Organic Elemental Analysis.

    ERIC Educational Resources Information Center

    Ma, T. S.; Wang, C. Y.

    1984-01-01

    Presents a literature review on methods used to analyze organic elements. Topic areas include methods for: (1) analyzing carbon, hydrogen, and nitrogen; (2) analyzing oxygen, sulfur, and halogens; (3) analyzing other elements; (4) simultaneously determining several elements; and (5) determing trace elements. (JN)

  2. Melt-melt immiscibility as result of synchronous melting of metapelites and impure marbles at crustal depth in the Moldanubian Zone, Bohemian Massif.

    NASA Astrophysics Data System (ADS)

    Ferrero, Silvio; O´Brien, Patrick J.; Ziemann, Martin A.; Wunder, Bernd; Hecht, Lutz; Wälle, Markus

    2016-04-01

    the commonly observed preferentially partitioning of REE in carbonatic melts with respect to silicatic melts. The formation of this carbonatic melt under conditions of primary melt-melt immiscibility at relatively shallow crustal levels is a novel finding. Primary carbonatic melts, i.e. carbonatites, are characteristically the product of partial melting of carbonates at mantle depths, or result from differentiation of deep, Ca-rich silicate melt during migration toward the surface. In the present case study, the protolith of these migmatites was likely a heterogeneous (meta)sedimentary sequence, mainly composed of pelitic sediments and including scattered lenses of impure limestones, which underwent synchronous partial melting during the Variscan orogeny.

  3. FUEL ELEMENT SUPPORT

    DOEpatents

    Wyman, W.L.

    1961-06-27

    The described cylindrical fuel element has longitudinally spaced sets of short longitudinal ribs circumferentially spaced from one another. The ribs support the fuel element in a coolant tube so that there is an annular space for coolant flow between the fuel element and the interior of the coolant tube. If the fuel element grows as a result of reactor operation, the circumferential distribution of the ribs maintains the uniformity of the annular space between the coolant tube and the fuel element, and the collapsibility of the ribs prevents the fuel element from becoming jammed in the coolant tube.

  4. Mixed fluid sources involved in diamond growth constrained by Sr-Nd-Pb-C-N isotopes and trace elements

    NASA Astrophysics Data System (ADS)

    Klein-BenDavid, Ofra; Pearson, D. Graham; Nowell, Geoff M.; Ottley, Chris; McNeill, John C. R.; Cartigny, Pierre

    2010-01-01

    Sub-micrometer inclusions in diamonds carry high-density fluids (HDF) from which the host diamonds have precipitated. The chemistry of these fluids is our best opportunity of characterizing the diamond-forming environment. The trace element patterns of diamond fluids vary within a limited range and are similar to those of carbonatitic/kimberlitic melts that originate from beneath the lithospheric mantle. A convecting mantle origin for the fluid is also implied by C isotopic compositions and by a preliminary Sr isotopic study (Akagi, T., Masuda, A., 1988. Isotopic and elemental evidence for a relationship between kimberlite and Zaire cubic diamonds. Nature 336, 665-667.). Nevertheless, the major element chemistry of HDFs is very different from that of kimberlites and carbonatites, varying widely and being characterized by extreme K enrichment (up to ˜ 39 wt.% on a water and carbonate free basis) and high volatile contents. The broad spectrum of major element compositions in diamond-forming fluids has been related to fluid-rock interaction and to immiscibility processes. Elemental signatures can be easily modified by a variety of mantle processes whereas radiogenic isotopes give a clear fingerprint of the time-integrated evolution of the fluid source region. Here we present the results of the first multi radiogenic-isotope (Sr, Nd, Pb) and trace element study on fluid-rich diamonds, implemented using a newly developed off-line laser sampling technique. The data are combined with N and C isotope analysis of the diamond matrix to better understand the possible sources of fluid involved in the formation of these diamonds. Sr isotope ratios vary significantly within single diamonds. The highly varied but unsupported Sr isotope ratios cannot be explained by immiscibility processes or fluid-mineral elemental fractionations occurring at the time of diamond growth. Our results demonstrate the clear involvement of a mixed fluid, with one component originating from ancient

  5. Element-ary Development.

    ERIC Educational Resources Information Center

    Schamp, Homer W., Jr.

    1989-01-01

    Describes the historic development of the periodic table from the four-element theory to the Lavoisier's table. Presents a table listing the old and new names of chemicals and the Lavoisier's table of elements. Lists two references. (YP)

  6. Trace Elements and Health

    ERIC Educational Resources Information Center

    Pettyjohn, Wayne A.

    1972-01-01

    Summarizes the effects of arsenic, lead, zinc, mercury, and cadmium on human health, indicates the sources of the elements in water, and considers the possibility of students in high schools analyzing water for trace amounts of the elements. (AL)

  7. Trace Elements and Health

    ERIC Educational Resources Information Center

    Pettyjohn, Wayne A.

    1972-01-01

    Summarizes the effects of arsenic, lead, zinc, mercury, and cadmium on human health, indicates the sources of the elements in water, and considers the possibility of students in high schools analyzing water for trace amounts of the elements. (AL)

  8. Element-ary Development.

    ERIC Educational Resources Information Center

    Schamp, Homer W., Jr.

    1989-01-01

    Describes the historic development of the periodic table from the four-element theory to the Lavoisier's table. Presents a table listing the old and new names of chemicals and the Lavoisier's table of elements. Lists two references. (YP)

  9. Orthotropic hole element

    NASA Technical Reports Server (NTRS)

    Markham, J. W.; Smith, C. V.

    1983-01-01

    A finite element was developed to adequately represent the state of stress in the region around a circular hole in orthotropic material experiencing reasonably general loading. This has been achieved through a complementary virtual work formulation of the stiffness and stress matrices for a square element with a center circular hole. The element has been incorporated into COSMIC/NASTRAN as a dummy element. Sample problems have been solved and these results are presented.

  10. NEUTRONIC REACTOR CONTROL ELEMENT

    DOEpatents

    Beaver, R.J.; Leitten, C.F. Jr.

    1962-04-17

    A boron-10 containing reactor control element wherein the boron-10 is dispersed in a matrix material is describeri. The concentration of boron-10 in the matrix varies transversely across the element from a minimum at the surface to a maximum at the center of the element, prior to exposure to neutrons. (AEC)

  11. Organic Elemental Analysis.

    ERIC Educational Resources Information Center

    Ma, T. S.; Gutterson, Milton

    1980-01-01

    Reviews general developments in computerization and data processing of organic elemental analyses; carbon, hydrogen, and nitrogen analyzers; procedures for determining oxygen, sulfur, and halogens, as well as other nometallic elements and organometallics. Selected papers on trace analysis of nonmetals and determination of metallic elements are…

  12. Elemental Chemical Puzzlers

    ERIC Educational Resources Information Center

    Thomas, Nicholas C.

    2009-01-01

    This paper provides nine short chemically based puzzles or problems extensible for use with students from middle school to college. Some of these will strengthen students' recognition of individual elements and element names. Others require students to focus on the salient properties of given chemical elements.

  13. Organic Elemental Analysis.

    ERIC Educational Resources Information Center

    Ma, T. S.; Gutterson, Milton

    1980-01-01

    Reviews general developments in computerization and data processing of organic elemental analyses; carbon, hydrogen, and nitrogen analyzers; procedures for determining oxygen, sulfur, and halogens, as well as other nometallic elements and organometallics. Selected papers on trace analysis of nonmetals and determination of metallic elements are…

  14. Microstructure and properties of heavily drawn Cu-Ag-Fe composites

    NASA Astrophysics Data System (ADS)

    Huang, J. S.; Yao, D. W.; Meng, L.

    2013-03-01

    Heavily drawn Cu-6 wt% Ag-2 wt% Fe, Cu-6 wt% Ag-4 wt% Fe and Cu-6 wt% Ag-6 wt% Fe were prepared by melting, homogenizing and cold drawing processes. The homogenizing treatment promotes the precipitation of secondary particles in the matrix, which results in finer and more uniform composite filaments in the drawn microstructure. With the increase of Fe content, the tensile strength increases but the electrical conductivity decreases. The strengthening of the composites and the decrease of the conductivity could be divided into two stages, which is explained by the non-homogeneous deformation model. At η = 5.6, dynamic recovery is thought to occur due to the temperature rise associated with severe deformation, leading to the sudden increase of the conductivity. A dislocation mechanism or an interface obstacle mechanism could be considered to be responsible for the strengthening and conducting behaviors.

  15. Immiscible Transition from Carbonate-rich to Silicate-rich Melts in Eclogite+CO2 and Genesis of Ocean Island Melilitite

    NASA Astrophysics Data System (ADS)

    Dasgupta, R.; Stalker, K.; Hirschmann, M. M.

    2004-12-01

    temperature interval of coexisting carbonate and silicate partial melts of carbonated eclogite is distinct from the continuous transition from carbonate to silicate melts observed in carbonated peridotite systems2,5. At high-temperature, the silicate melts generated from SLEC1 are comparable to strongly silica-undersaturated, alkalic OIB lavas and closely resembles ocean island melilitite and nepheline melilitite3,4 in its SiO2, FeO*, MgO, CaO, TiO2, and Na2O content. They are also similar to melilite bearing lavas of continental affinity, though the match is not as close. Although the SLEC1 derived immiscible silicate melts are lower in Al2O3 than primitive alkalic OIB lavas, liquids richer in Al2O3 may be produced at slightly lower pressures. Geochemical and geodynamical investigations of carbonated eclogite sources for melilitic volcanic series thus merit consideration. 1. Brey, G and Green, D. H. 1977, CMP 61, 141-162. 2. Hirose, K. 1997, GRL 24, 2837-2840. 3. Clague, D. A. and Frey, F. A. 1982, JP 23, 447-504. 4. Hoernle, K. and Schmincke, H.-U. 1993, JP 34, 573-597. 5. Moore, K. R. and Wood, B. J. 1998, JP 39, 1943-1951.

  16. Elemental Solubility Tendency for the Phases of Uranium by Classical Models Used to Predict Alloy Behavior

    SciTech Connect

    Van Blackwood; Travis Koenig; Saleem Drera; Brajenda Mishra; Davis Olson; Doug Porter; Robert Mariani

    2012-03-01

    Traditional alloy theory models, specifically Darken-Gurry and Miedema’s analyses, that characterize solutes in solid solvents relative to physical properties of the elements have been used to assist in predicting alloy behavior. These models will be applied relative to the three solid phases of uranium: alpha (orthorhombic), beta (tetragonal), and gamma (bcc). These phases have different solubilities for specific alloy additions as a function of temperature. The Darken-Gurry and Miedema models, with modifications based on concepts of Waber, Gschneider, and Brewer will be used to predict the behavior of four types of solutes: 1) Transition metals that are used for various purposes associated with the containment as alloy additions in the uranium fuel 2) Transuranic elements in the uranium 3) Rare earth fission products (lanthanides) 4) Transition metals and other fission products Using these solute map criteria, elemental behavior will be predicted as highly soluble, marginally soluble, or immiscible (compound formers) and will be used to compare solute effects during uranium phase transformations. The overlapping of these solute maps are convenient first approximation tools for predicting alloy behavior.

  17. The synthetic elements

    SciTech Connect

    Hoffman, D.C.

    1990-05-01

    Prior to 1940, the heaviest element known was uranium, discovered in 1789. Since that time the elements 93 through 109 have been synthesized and identified and the elements 43, 61, 85, and 87 which were missing form the periodic tables of the 1930's have been discovered. The techniques and problems involved in these discoveries and the placement of the transuranium elements in the periodic table will be discussed. The production and positive identification of elements heavier than Md (Z=101), which have very short half-lives and can only be produced an atom-at-a-time, are very difficult and there have been controversies concerning their discovery. Some of the new methods which have been developed and used in these studies will be described. The prospects for production of still heavier elements will be considered.

  18. Cohesive Elements for Shells

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

    2007-01-01

    A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

  19. Chemistry of superheavy elements.

    PubMed

    Schädel, Matthias

    2006-01-09

    The number of chemical elements has increased considerably in the last few decades. Most excitingly, these heaviest, man-made elements at the far-end of the Periodic Table are located in the area of the long-awaited superheavy elements. While physical techniques currently play a leading role in these discoveries, the chemistry of superheavy elements is now beginning to be developed. Advanced and very sensitive techniques allow the chemical properties of these elusive elements to be probed. Often, less than ten short-lived atoms, chemically separated one-atom-at-a-time, provide crucial information on basic chemical properties. These results place the architecture of the far-end of the Periodic Table on the test bench and probe the increasingly strong relativistic effects that influence the chemical properties there. This review is focused mainly on the experimental work on superheavy element chemistry. It contains a short contribution on relativistic theory, and some important historical and nuclear aspects.

  20. Multifacet holographic optical elements

    NASA Technical Reports Server (NTRS)

    Case, S. K.; Haugen, P. R.

    1981-01-01

    New types of holographic optical elements, combining the flexibility of computer generated holograms with the large space bandwidth product and high diffraction efficiency of interferometrically recorded volume phase holograms, are demonstrated. The optical elements are recorded by subdividing a volume hologram film surface into numerous small areas (facets), each of which is individually exposed under computer control. Each facet is used to produce a portion of the desired final wavefront. Three different optical elements are demonstrated.

  1. NEUTRONIC REACTOR CONTROL ELEMENT

    DOEpatents

    Newson, H.W.

    1960-09-13

    A novel composite neutronic reactor control element is offered. The element comprises a multiplicity of sections arranged in end-to-end relationship, each of the sections having a markedly different neutron-reactive characteristic. For example, a three-section control element could contain absorber, moderator, and fuel sections. By moving such an element longitudinally through a reactor core, reactivity is decreased by the absorber, increased slightly by the moderator, or increased substantially by the fuel. Thus, control over a wide reactivity range is provided.

  2. FUEL ELEMENT INTERLOCKING ARRANGEMENT

    DOEpatents

    Fortescue, P.; Nicoll, D.

    1963-01-01

    This patent relates to a system for mutually interlocking a multiplicity of elongated, parallel, coextensive, upright reactor fuel elements so as to render a laterally selfsupporting bundle, while admitting of concurrent, selective, vertical withdrawal of a sizeable number of elements without any of the remaining elements toppling, Each element is provided with a generally rectangular end cap. When a rank of caps is aligned in square contact, each free edge centrally defines an outwardly profecting dovetail, and extremitally cooperates with its adjacent cap by defining a juxtaposed half of a dovetail- receptive mortise. Successive ranks are staggered to afford mating of their dovetails and mortises. (AEC)

  3. Immiscible Fe- and Si-rich silicate melts in plagioclase from the Baima mafic intrusion (SW China): Implications for the origin of bi-modal igneous suites in large igneous provinces

    NASA Astrophysics Data System (ADS)

    Liu, Ping-Ping; Zhou, Mei-Fu; Ren, Zhongyuan; Wang, Christina Yan; Wang, Kun

    2016-09-01

    The Emeishan large igneous province (ELIP) in SW China is characterized by voluminous high-Ti and low-Ti basalts and spatially associated Fe-Ti oxide-bearing mafic-ultramafic and syenitic/granitic intrusions. The Baima layered mafic intrusion in the central part of the ELIP is surrounded by syenitic and granitic rocks and contains a Lower Zone of interlayered Fe-Ti oxide ores, troctolites and clinopyroxenites and an Upper Zone of isotropic olivine gabbros and gabbros (UZa) and apatite gabbros and Fe-Ti-P oxide ores (UZb). Polycrystalline mineral inclusions, for the first time, were observed in primocryst plagioclase from the basal part of the UZa through to the top of the UZb and consist mostly of clinopyroxene, plagioclase, magnetite, ilmenite and apatite with minor orthopyroxene, sulfide and hornblende. These minerals are commonly anhedral and form irregular shapes. Daughter plagioclase usually crystallizes on the walls of host primocryst plagioclase and has An contents typically 3-6 An% lower than the host plagioclase. Daughter clinopyroxene has similar Mg# but lower TiO2 and Al2O3 contents than primocryst clinopyroxene. These polycrystalline mineral inclusions are considered to crystallize from melts contemporaneous with host plagioclase. The compositional differences between daughter and primocryst minerals can be attributed to equilibrium crystallization in a closed system of the trapped melt inclusions in contrast to fractional crystallization and possible magma replenishment in an open system typical for primo-cumulates of large layered intrusions. Heated and homogenized melt inclusions have variable SiO2 (33-52 wt%), CaO (7-20 wt%), TiO2 (0.1-12 wt%), FeOt (5-20 wt%), P2O5 (0.2-10 wt%) and K2O (0-2.2 wt%). The large ranges of melt compositions are interpreted to result from heterogeneous trapping of different proportions of immiscible Si-rich and Fe-Ti-rich silicate liquids, together with entrapment of various microphenocrysts. The separation of micrometer

  4. The Elements of Empathy.

    ERIC Educational Resources Information Center

    Iannotti, Ronald J.

    When assessing the influence of empathy on prosocial motivation, analyzing empathy alone would lead to a misunderstanding. We must also assess other elements of the situation, such as the altruist's coping skills and situational constraints. In a similar manner empathy itself should be conceptualized as a process with many elements. One way to…

  5. Automatic finite element generators

    NASA Technical Reports Server (NTRS)

    Wang, P. S.

    1984-01-01

    The design and implementation of a software system for generating finite elements and related computations are described. Exact symbolic computational techniques are employed to derive strain-displacement matrices and element stiffness matrices. Methods for dealing with the excessive growth of symbolic expressions are discussed. Automatic FORTRAN code generation is described with emphasis on improving the efficiency of the resultant code.

  6. Movies and Literary Elements.

    ERIC Educational Resources Information Center

    Keller, Rodney D.

    Showing ten-minute movie clips can be an effective way to motivate students to read literature and to teach elements of fiction, namely plot, character, setting, symbol, irony, and theme. A clip from "And Then There Were None" may be used to teach various elements of plot, including conflict and the four types of conflict (man vs. man,…

  7. The Elements Drawing.

    ERIC Educational Resources Information Center

    Dkeidek, Iyad M.

    2003-01-01

    Presents an educational game designed for first- or second-year high school students who have already studied themes related to the periodic table elements, such as their symbols, electronic configurations, properties, and uses. The game is designed to help students learn the symbols of the elements and their properties or uses in a fun, engaging…

  8. The Elements Drawing.

    ERIC Educational Resources Information Center

    Dkeidek, Iyad M.

    2003-01-01

    Presents an educational game designed for first- or second-year high school students who have already studied themes related to the periodic table elements, such as their symbols, electronic configurations, properties, and uses. The game is designed to help students learn the symbols of the elements and their properties or uses in a fun, engaging…

  9. NEUTRONIC REACTOR FUEL ELEMENT

    DOEpatents

    Kesselring, K.A.; Seybolt, A.U.

    1958-12-01

    A reactor fuel element of the capillary tube type is described. The element consists of a thin walled tube, sealed at both ends, and having an interior coatlng of a fissionable material, such as uranium enriched in U-235. The tube wall is gas tight and is constructed of titanium, zirconium, or molybdenum.

  10. Movies and Literary Elements.

    ERIC Educational Resources Information Center

    Keller, Rodney D.

    Showing ten-minute movie clips can be an effective way to motivate students to read literature and to teach elements of fiction, namely plot, character, setting, symbol, irony, and theme. A clip from "And Then There Were None" may be used to teach various elements of plot, including conflict and the four types of conflict (man vs. man,…

  11. Elemental Food for Thought

    ERIC Educational Resources Information Center

    Cady, Susan

    2005-01-01

    One of the first tasks students learn in chemistry is to pronounce and spell the names of elements and learn their corresponding chemical symbols. Repetitive oral recitation is commonly used to learn this information, but games and puzzles can make this task creative, variable, and fun. Elemental Food for Thought is a puzzlelike activity that…

  12. Proceedings of transuranium elements

    SciTech Connect

    Not Available

    1992-01-01

    The identification of the first synthetic elements was established by chemical evidence. Conclusive proof of the synthesis of the first artificial element, technetium, was published in 1937 by Perrier and Segre. An essential aspect of their achievement was the prediction of the chemical properties of element 43, which had been missing from the periodic table and which was expected to have properties similar to those of manganese and rhenium. The discovery of other artificial elements, astatine and francium, was facilitated in 1939-1940 by the prediction of their chemical properties. A little more than 50 years ago, in the spring of 1940, Edwin McMillan and Philip Abelson synthesized element 93, neptunium, and confirmed its uniqueness by chemical means. On August 30, 1940, Glenn Seaborg, Arthur Wahl, and the late Joseph Kennedy began their neutron irradiations of uranium nitrate hexahydrate. A few months later they synthesized element 94, later named plutonium, by observing the alpha particles emitted from uranium oxide targets that had been bombarded with deuterons. Shortly thereafter they proved that is was the second transuranium element by establishing its unique oxidation-reduction behavior. The symposium honored the scientists and engineers whose vision and dedication led to the discovery of the transuranium elements and to the understanding of the influence of 5f electrons on their electronic structure and bonding. This volume represents a record of papers presented at the symposium.

  13. Elemental Food for Thought

    ERIC Educational Resources Information Center

    Cady, Susan

    2005-01-01

    One of the first tasks students learn in chemistry is to pronounce and spell the names of elements and learn their corresponding chemical symbols. Repetitive oral recitation is commonly used to learn this information, but games and puzzles can make this task creative, variable, and fun. Elemental Food for Thought is a puzzlelike activity that…

  14. MOLDED SEALING ELEMENT

    DOEpatents

    Bradford, B.W.; Skinner, W.J.

    1959-03-24

    Molded sealing elements suitable for use under conditions involving exposure to uranium hexafluoride vapor are described. Such sealing elements are made by subjecting graphitic carbons to a preliminary treatment with uranium hexafluoride vapor, and then incorporating polytetrafluorethylene in them. The resulting composition has good wear resistant and frictional properties and is resistant to disintegration by uranium hexafluoride over long periods of exposure.

  15. NUCLEAR REACTOR FUEL ELEMENT

    DOEpatents

    Wheelock, C.W.; Baumeister, E.B.

    1961-09-01

    A reactor fuel element utilizing fissionable fuel materials in plate form is described. This fuel element consists of bundles of fuel-bearing plates. The bundles are stacked inside of a tube which forms the shell of the fuel element. The plates each have longitudinal fins running parallel to the direction of coolant flow, and interspersed among and parallel to the fins are ribs which position the plates relative to each other and to the fuel element shell. The plate bundles are held together by thin bands or wires. The ex tended surface increases the heat transfer capabilities of a fuel element by a factor of 3 or more over those of a simple flat plate.

  16. The heaviest elements

    SciTech Connect

    Hoffman, D.C. Lawrence Berkeley Lab., CA )

    1994-05-02

    How long does an atom need to exist before it's possible to do any meaningful chemistry on it Is it possible to learn anything at all about the reactions of an element for which no more than a few dozen atoms have ever existed simultaneously These are some of the questions colleagues in a few laboratories worldwide attempt to answer as they investigate the chemistry of the heaviest elements--elements produced one atom at a time in accelerators by bombarding radioactive targets with high-intensity beams of heavy ions. All of these elements spontaneously decay; the most stable of them have half-lives of only a few minutes, some that are less stable exist for only milliseconds. So far, no chemical studies have been performed on elements whose longest lived isotopes last only milliseconds because the difficulties of doing chemistry on this time scale under highly radioactive conditions are enormous. Over the past 10 years, however, nuclear chemists have developed new techniques or adapted existing ones to begin to probe the chemical properties of those very heavy elements that have half-lives in the range of seconds to minutes. Although the classic experiments are now nearly 40 years old, they are worth describing, as they were the first of their kind and illustrate many of the techniques that are still used and essential in studying these very short-lived, radioactive elements.

  17. Three-Dimensional Elemental Imaging of Nantan Meteorite via Femtosecond Laser Ionization Time-of-Flight Mass Spectrometry.

    PubMed

    He, Miaohong; Meng, Yifan; Yan, Shanshan; Hang, Wei; Zhou, Wenge; Huang, Benli

    2017-01-03

    Femtosecond laser ionization time-of-flight mass spectrometry (fs-LI-TOFMS) is introduced for the three-dimensional elemental analysis of a Nantan meteorite. Spatially resolved multielemental imaging of major and minor compositions in a meteorite are presented with a lateral resolution of 50 μm and a depth resolution of 7 μm. Distinct 3D distributions of siderophile, lithophile, and chalcophile elements are revealed. Co and Ni are highly siderophile (Iron-loving), mainly enriched in the metal phase. Cr, Cu, V, and Mn are enriched in the sulfide for their chalcophile (S-loving) tendency. S, P, and C aggregate together in the analytical volume. Silicate inclusion, containing lithophile elements of Al, Ca, Mg, K, and so on, is embedded within the metal phase for the immiscibility between silicate inclusion and the melted metal phase. These 3D distributions of elements aid the exploration of the formation and evolution of the meteorite. They also reveal the feasibility of fs-LI-TOFMS as a versatile tool for 3D imaging.

  18. Neutronic fuel element fabrication

    DOEpatents

    Korton, George

    2004-02-24

    This disclosure describes a method for metallurgically bonding a complete leak-tight enclosure to a matrix-type fuel element penetrated longitudinally by a multiplicity of coolant channels. Coolant tubes containing solid filler pins are disposed in the coolant channels. A leak-tight metal enclosure is then formed about the entire assembly of fuel matrix, coolant tubes and pins. The completely enclosed and sealed assembly is exposed to a high temperature and pressure gas environment to effect a metallurgical bond between all contacting surfaces therein. The ends of the assembly are then machined away to expose the pin ends which are chemically leached from the coolant tubes to leave the coolant tubes with internal coolant passageways. The invention described herein was made in the course of, or under, a contract with the U.S. Atomic Energy Commission. It relates generally to fuel elements for neutronic reactors and more particularly to a method for providing a leak-tight metal enclosure for a high-performance matrix-type fuel element penetrated longitudinally by a multiplicity of coolant tubes. The planned utilization of nuclear energy in high-performance, compact-propulsion and mobile power-generation systems has necessitated the development of fuel elements capable of operating at high power densities. High power densities in turn require fuel elements having high thermal conductivities and good fuel retention capabilities at high temperatures. A metal clad fuel element containing a ceramic phase of fuel intimately mixed with and bonded to a continuous refractory metal matrix has been found to satisfy the above requirements. Metal coolant tubes penetrate the matrix to afford internal cooling to the fuel element while providing positive fuel retention and containment of fission products generated within the fuel matrix. Metal header plates are bonded to the coolant tubes at each end of the fuel element and a metal cladding or can completes the fuel-matrix enclosure

  19. Elements in biological AMS

    SciTech Connect

    Vogel, J.S.; McAninch, J.; Freeman, S.

    1996-08-01

    AMS (Accelerator Mass Spectrometry) provides high detection sensitivity for isotopes whose half-lives are between 10 years and 100 million years. {sup 14}C is the most developed of such isotopes and is used in tracing natural and anthropogenic organic compounds in the Earth`s biosphere. Thirty-three elements in the main periodic table and 17 lanthanides or actinides have long lived isotopes, providing potential tracers for research in elemental biochemistry. Overlap of biologically interesting heavy elements and possible AMS tracers is discussed.

  20. NEUTRONIC REACTOR FUEL ELEMENT

    DOEpatents

    Shackleford, M.H.

    1958-12-16

    A fuel element possessing good stability and heat conducting properties is described. The fuel element comprises an outer tube formed of material selected from the group consisting of stainhess steel, V, Ti. Mo. or Zr, a fuel tube concentrically fitting within the outer tube and containing an oxide of an isotope selected from the group consisting of U/sup 235/, U/sup 233/, and Pu/sup 239/, and a hollow, porous core concentrically fitting within the fuel tube and formed of an oxide of an element selected from the group consisting of Mg, Be, and Zr.

  1. Experiments on Superheavy Elements

    NASA Astrophysics Data System (ADS)

    Hofmann, Sigurd

    An overview of present experimental investigation of superheavy elements is given. Using cold fusion reactions which are based on lead and bismuth targets, relatively neutron deficient isotopes of the elements from 107 to 113 were synthesized at GSI in Darmstadt, Germany, and/or at RIKEN in Wako, Japan. In hot fusion reactions of 48Ca projectiles with actinide targets more neutron rich isotopes of the elements from 112 to 116 and even 118 were produced at FLNR in Dubna, Russia. Recently, part of these data which represent the first identification of nuclei located on the predicted island of SHEs were confirmed in two independent experiments. The data are compared with theoretical descriptions.

  2. NUCLEAR REACTOR FUEL ELEMENT

    DOEpatents

    Anderson, W.F.; Tellefson, D.R.; Shimazaki, T.T.

    1962-04-10

    A plate type fuel element which is particularly useful for organic cooled reactors is described. Generally, the fuel element comprises a plurality of fissionable fuel bearing plates held in spaced relationship by a frame in which the plates are slidably mounted in grooves. Clearance is provided in the grooves to allow the plates to expand laterally. The plates may be rigidly interconnected but are floatingly supported at their ends within the frame to allow for longi-tudinal expansion. Thus, this fuel element is able to withstand large temperature differentials without great structural stresses. (AEC)

  3. Elements of discovery.

    PubMed

    Toledo-Pereyra, Luis H

    2008-01-01

    I understand discovery as the essence of thinking man, or to paraphrase the notable French philosopher René Descartes, "I think, therefore I discover." In this study, I introduce discovery as the foundation of modern science. Discovery consists of six stages or elements, including: concept, belief, ability, support, proof, and protection. Each element is discussed within the context of the whole discovery enterprise. Fundamental tenets for understanding discovery are given throughout the paper, and a few examples illustrate the significance of some of the most important elements. I invite clinicians, researchers, and/or clinical researchers to integrate themselves into the active process of discovery. Remember--I think, therefore I discover.

  4. Injector element characterization methodology

    NASA Technical Reports Server (NTRS)

    Cox, George B., Jr.

    1988-01-01

    Characterization of liquid rocket engine injector elements is an important part of the development process for rocket engine combustion devices. Modern nonintrusive instrumentation for flow velocity and spray droplet size measurement, and automated, computer-controlled test facilities allow rapid, low-cost evaluation of injector element performance and behavior. Application of these methods in rocket engine development, paralleling their use in gas turbine engine development, will reduce rocket engine development cost and risk. The Alternate Turbopump (ATP) Hot Gas Systems (HGS) preburner injector elements were characterized using such methods, and the methodology and some of the results obtained will be shown.

  5. Discovery of element 112

    SciTech Connect

    Hofmann, S.

    1996-12-31

    The new elements 110, 111, and 112 were synthesized and unambiguously identified in experiments at SHIP. Due to strong shell effects the dominant decay mode is not fission, but emission of alpha particles. Theoretical investigations predict that maximum shell effects should exist in nuclei near proton number 114 and neutron number 184. Measurements give hope that isotopes of element 114 close to the island of spherical Superheavy Elements could be produced by fusion reactions using {sup 118}Pb as target. systematic studies of the reaction cross-sections indicate that transfer of nucleons is the important process to initiate the fusion.

  6. Multi-Element Airfoil System

    NASA Technical Reports Server (NTRS)

    Turner, Travis L. (Inventor); Khorrami, Mehdi R. (Inventor); Lockard, David P. (Inventor); McKenney, Martin J. (Inventor); Atherley, Raymond D. (Inventor); Kidd, Reggie T. (Inventor)

    2014-01-01

    A multi-element airfoil system includes an airfoil element having a leading edge region and a skin element coupled to the airfoil element. A slat deployment system is coupled to the slat and the skin element, and is capable of deploying and retracting the slat and the skin element. The skin element substantially fills the lateral gap formed between the slat and the airfoil element when the slat is deployed. The system further includes an uncoupling device and a sensor to remove the skin element from the gap based on a critical angle-of-attack of the airfoil element. The system can alternatively comprise a trailing edge flap, where a skin element substantially fills the lateral gap between the flap and the trailing edge region of the airfoil element. In each case, the skin element fills a gap between the airfoil element and the deployed flap or slat to reduce airframe noise.

  7. Rock in Its Elements

    ERIC Educational Resources Information Center

    MacCluskey, Thomas

    1969-01-01

    A discussion of the following musical elements of rock: rhythm, melody, harmony, and form. A impromptu analysis made at a session of the Youth Music Symposium, July 25, 1969. Remarks transcribed from tape. (Author/AP)

  8. Space Radiation Program Element

    NASA Technical Reports Server (NTRS)

    Krenek, Sam

    2008-01-01

    This poster presentation shows the various elements of the Space Radiation Program. It reviews the program requirements: develop and validate standards, quantify space radiation human health risks, mitigate risks through countermeasures and technologies, and treat and monitor unmitigated risks.

  9. Transposable elements in cancer.

    PubMed

    Burns, Kathleen H

    2017-07-01

    Transposable elements give rise to interspersed repeats, sequences that comprise most of our genomes. These mobile DNAs have been historically underappreciated - both because they have been presumed to be unimportant, and because their high copy number and variability pose unique technical challenges. Neither impediment now seems steadfast. Interest in the human mobilome has never been greater, and methods enabling its study are maturing at a fast pace. This Review describes the activity of transposable elements in human cancers, particularly long interspersed element-1 (LINE-1). LINE-1 sequences are self-propagating, protein-coding retrotransposons, and their activity results in somatically acquired insertions in cancer genomes. Altered expression of transposable elements and animation of genomic LINE-1 sequences appear to be hallmarks of cancer, and can be responsible for driving mutations in tumorigenesis.

  10. New functionalities in abundant element oxides: ubiquitous element strategy.

    PubMed

    Hosono, Hideo; Hayashi, Katsuro; Kamiya, Toshio; Atou, Toshiyuki; Susaki, Tomofumi

    2011-06-01

    While most ceramics are composed of ubiquitous elements (the ten most abundant elements within the Earth's crust), many advanced materials are based on rare elements. A 'rare-element crisis' is approaching owing to the imbalance between the limited supply of rare elements and the increasing demand. Therefore, we propose a 'ubiquitous element strategy' for materials research, which aims to apply abundant elements in a variety of innovative applications. Creation of innovative oxide materials and devices based on conventional ceramics is one specific challenge. This review describes the concept of ubiquitous element strategy and gives some highlights of our recent research on the synthesis of electronic, thermionic and structural materials using ubiquitous elements.

  11. JACKETED FUEL ELEMENT

    DOEpatents

    Wigner, E.P.; Szilard, L.; Creutz, E.C.

    1959-02-01

    These fuel elements are comprised of a homogeneous metallic uranium body completely enclosed and sealed in an aluminum cover. The uranium body and aluminum cover are bonded together by a layer of zinc located between them. The bonding layer serves to improve transfer of heat, provides an additional protection against corrosion of the uranium by the coolant, and also localizes any possible corrosion by preventing travel of corrosive material along the surface of the fuel element.

  12. COMPOSITE FUEL ELEMENT

    DOEpatents

    Hurford, W.J.; Gordon, R.B.; Johnson, W.A.

    1962-12-25

    A sandwich-type fuel element for a reactor is described. This fuel element has the shape of an elongated flat plate and includes a filler plate having a plurality of compartments therein in which the fuel material is located. The filler plate is clad on both sides with a thin cladding material which is secured to the filler plate only to completely enclose the fuel material in each compartment. (AEC)

  13. Trace elements in dialysis.

    PubMed

    Filler, Guido; Felder, Sarah

    2014-08-01

    In end-stage chronic kidney disease (CKD), pediatric nephrologists must consider the homeostasis of the multiple water-soluble ions that are influenced by renal replacement therapy (RRT). While certain ions such as potassium and calcium are closely monitored, little is known about the handling of trace elements in pediatric dialysis. RRT may lead to accumulation of toxic trace elements, either due to insufficient elimination or due to contamination, or to excessive removal of essential trace elements. However, trace elements are not routinely monitored in dialysis patients and no mechanism for these deficits or toxicities has been established. This review summarizes the handling of trace elements, with particular attention to pediatric data. The best data describe lead and indicate that there is a higher prevalence of elevated lead (Pb, atomic number 82) levels in children on RRT when compared to adults. Lead is particularly toxic in neurodevelopment and lead levels should therefore be monitored. Monitoring of zinc (Zn, atomic number 30) and selenium (Se, atomic number 34) may be indicated in the monitoring of all pediatric dialysis patients to reduce morbidity from deficiency. Prospective studies evaluating the impact of abnormal trace elements and the possible therapeutic value of intervention are required.

  14. Elemental sulfur coarsening kinetics.

    PubMed

    Garcia, Angel A; Druschel, Gregory K

    Elemental sulfur exists is a variety of forms in natural systems, from dissolved forms (noted as S8(diss) or in water as S8(aq)) to bulk elemental sulfur (most stable as α-S8). Elemental sulfur can form via several biotic and abiotic processes, many beginning with small sulfur oxide or polysulfidic sulfur molecules that coarsen into S8 rings that then coalesce into larger forms: [Formula: see text] Formation of elemental sulfur can be possible via two primary techniques to create an emulsion of liquid sulfur in water called sulfur sols that approximate some mechanisms of possible elemental sulfur formation in natural systems. These techniques produce hydrophobic (S8(Weimarn)) and hydrophilic (S8(polysulfide)) sols that exist as nanoparticle and colloidal suspensions. These sols begin as small sulfur oxide or polysulfidic sulfur molecules, or dissolved S8(aq) forms, but quickly become nanoparticulate and coarsen into micron sized particles via a combination of classical nucleation, aggregation processes, and/or Ostwald ripening. We conducted a series of experiments to study the rate of elemental sulfur particle coarsening using dynamic light scattering (DLS) analysis under different physical and chemical conditions. Rates of nucleation and initial coarsening occur over seconds to minutes at rates too fast to measure by DLS, with subsequent coarsening of S8(nano) and S8(sol) being strongly temperature dependent, with rates up to 20 times faster at 75°C compared to 20°C. The addition of surfactants (utilizing ionic and nonionic surfactants as model compounds) results in a significant reduction of coarsening rates, in addition to known effects of these molecules on elemental sulfur solubility. DLS and cryo-SEM results suggest coarsening is largely a product of ripening processes rather than particle aggregation, especially at higher temperatures. Fitting of the coarsening rate data to established models for Ostwald ripening additionally support this as a primary

  15. Employment Administration: Elements and Effects.

    ERIC Educational Resources Information Center

    Webb, Mel

    1983-01-01

    The basic elements of personnel administration are defined and examined and the interaction between the elements are described. The elements include job analysis, job classification, recruitment, selection, induction into the organization, evaluation of job performance, and termination. (MLW)

  16. Nuclear fuel element

    DOEpatents

    Zocher, Roy W.

    1991-01-01

    A nuclear fuel element and a method of manufacturing the element. The fuel element is comprised of a metal primary container and a fuel pellet which is located inside it and which is often fragmented. The primary container is subjected to elevated pressure and temperature to deform the container such that the container conforms to the fuel pellet, that is, such that the container is in substantial contact with the surface of the pellet. This conformance eliminates clearances which permit rubbing together of fuel pellet fragments and rubbing of fuel pellet fragments against the container, thus reducing the amount of dust inside the fuel container and the amount of dust which may escape in the event of container breach. Also, as a result of the inventive method, fuel pellet fragments tend to adhere to one another to form a coherent non-fragmented mass; this reduces the tendency of a fragment to pierce the container in the event of impact.

  17. Elemental sulfur recovery process

    DOEpatents

    Flytzani-Stephanopoulos, Maria; Hu, Zhicheng

    1993-01-01

    An improved catalytic reduction process for the direct recovery of elemental sulfur from various SO.sub.2 -containing industrial gas streams. The catalytic process provides combined high activity and selectivity for the reduction of SO.sub.2 to elemental sulfur product with carbon monoxide or other reducing gases. The reaction of sulfur dioxide and reducing gas takes place over certain catalyst formulations based on cerium oxide. The process is a single-stage, catalytic sulfur recovery process in conjunction with regenerators, such as those used in dry, regenerative flue gas desulfurization or other processes, involving direct reduction of the SO.sub.2 in the regenerator off gas stream to elemental sulfur in the presence of a catalyst.

  18. Elemental sulfur recovery process

    DOEpatents

    Flytzani-Stephanopoulos, M.; Zhicheng Hu.

    1993-09-07

    An improved catalytic reduction process for the direct recovery of elemental sulfur from various SO[sub 2]-containing industrial gas streams. The catalytic process provides combined high activity and selectivity for the reduction of SO[sub 2] to elemental sulfur product with carbon monoxide or other reducing gases. The reaction of sulfur dioxide and reducing gas takes place over certain catalyst formulations based on cerium oxide. The process is a single-stage, catalytic sulfur recovery process in conjunction with regenerators, such as those used in dry, regenerative flue gas desulfurization or other processes, involving direct reduction of the SO[sub 2] in the regenerator off gas stream to elemental sulfur in the presence of a catalyst. 4 figures.

  19. Transposable elements in Drosophila

    PubMed Central

    McCullers, Tabitha J.; Steiniger, Mindy

    2017-01-01

    ABSTRACT Transposable elements (TEs) are mobile genetic elements that can mobilize within host genomes. As TEs comprise more than 40% of the human genome and are linked to numerous diseases, understanding their mechanisms of mobilization and regulation is important. Drosophila melanogaster is an ideal model organism for the study of eukaryotic TEs as its genome contains a diverse array of active TEs. TEs universally impact host genome size via transposition and deletion events, but may also adopt unique functional roles in host organisms. There are 2 main classes of TEs: DNA transposons and retrotransposons. These classes are further divided into subgroups of TEs with unique structural and functional characteristics, demonstrating the significant variability among these elements. Despite this variability, D. melanogaster and other eukaryotic organisms utilize conserved mechanisms to regulate TEs. This review focuses on the transposition mechanisms and regulatory pathways of TEs, and their functional roles in D. melanogaster. PMID:28580197

  20. Probabilistic boundary element method

    NASA Technical Reports Server (NTRS)

    Cruse, T. A.; Raveendra, S. T.

    1989-01-01

    The purpose of the Probabilistic Structural Analysis Method (PSAM) project is to develop structural analysis capabilities for the design analysis of advanced space propulsion system hardware. The boundary element method (BEM) is used as the basis of the Probabilistic Advanced Analysis Methods (PADAM) which is discussed. The probabilistic BEM code (PBEM) is used to obtain the structural response and sensitivity results to a set of random variables. As such, PBEM performs analogous to other structural analysis codes such as finite elements in the PSAM system. For linear problems, unlike the finite element method (FEM), the BEM governing equations are written at the boundary of the body only, thus, the method eliminates the need to model the volume of the body. However, for general body force problems, a direct condensation of the governing equations to the boundary of the body is not possible and therefore volume modeling is generally required.