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Sample records for frustrated phase separation

  1. Single Sublattice Endotaxial Phase Separation Driven by Charge Frustration in a Complex Oxide

    PubMed Central

    2013-01-01

    Complex transition-metal oxides are important functional materials in areas such as energy and information storage. The cubic ABO3 perovskite is an archetypal example of this class, formed by the occupation of small octahedral B-sites within an AO3 network defined by larger A cations. We show that introduction of chemically mismatched octahedral cations into a cubic perovskite oxide parent phase modifies structure and composition beyond the unit cell length scale on the B sublattice alone. This affords an endotaxial nanocomposite of two cubic perovskite phases with distinct properties. These locally B-site cation-ordered and -disordered phases share a single AO3 network and have enhanced stability against the formation of a competing hexagonal structure over the single-phase parent. Synergic integration of the distinct properties of these phases by the coherent interfaces of the composite produces solid oxide fuel cell cathode performance superior to that expected from the component phases in isolation. PMID:23750709

  2. Frustration-induced quantum phases in mixed spin chain with frustrated side chains

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Takano, Ken'Ichi

    2008-08-01

    A mixed Heisenberg spin chain with frustrated side chains is investigated by numerical and perturbational calculations. A frustration-induced quantum partially polarized ferrimagnetic phase and a nonmagnetic spin quadrupolar phase are found adjacent to the conventional Lieb-Mattis-type ferrimagnetic phase or the nonmagnetic singlet cluster solid phases. The partially polarized ferrimagnetic phase has an incommensurate spin structure. Similar structures are commonly found in other frustration-induced partially polarized ferrimagnetic phases. Numerical results also suggest a series of almost critical nonmagnetic ground states in a highly frustrated regime if the side chain spins weakly couple to the main chain.

  3. Topological phase transitions in frustrated magnets

    NASA Astrophysics Data System (ADS)

    Southern, B. W.; Peles, A.

    2006-06-01

    The role of topological excitations in frustrated Heisenberg antiferromagnets between two and three spatial dimensions is considered. In particular, the antiferromagnetic Heisenberg model on a stacked triangular geometry with a finite number of layers is studied using Monte Carlo methods. A phase transition that is purely topological in nature occurs at a finite temperature for all film thicknesses. The results indicate that topological excitations are important for a complete understanding of the critical properties of the model between two and three dimensions.

  4. Frustration and curvature - Glasses and the cholesteric blue phase

    NASA Technical Reports Server (NTRS)

    Sethna, J. P.

    1983-01-01

    An analogy is drawn between continuum elastic theories of the blue phase of cholesteric liquid crystals and recent theories of frustration in configurational glasses. Both involve the introduction of a lattice of disclination lines to relieve frustration; the frustration is due to an intrinsic curvature in the natural form of parallel transport. A continuum theory of configurational glasses is proposed.

  5. Microfluidic Separation of Ethylene and Ethane Using Frustrated Lewis Pairs.

    PubMed

    Voicu, Dan; Stephan, Douglas W; Kumacheva, Eugenia

    2015-12-21

    Separation of gaseous olefins and paraffins is one of the most important separation processes in the industry. Development of new cost-effective technologies aims at reducing the high energy consumption during the separation process. Here, we took advantage of the reaction of frustrated Lewis pairs (FLPs) with ethylene to achieve reactive extraction of ethylene from ethylene-ethane mixtures. The extraction was studied using a microfluidic platform, which enabled a rapid, high-throughput assessment of reaction conditions to optimize gas separation efficiency. A separation factor of 7.3 was achieved for ethylene from a 1:1 volume ratio mixture of ethylene and ethane, which corresponded to an extracted ethylene purity of 88 %. The results obtained in the microfluidic studies were validated using infrared spectroscopy. This work paves the way for further development of the FLPs and optimization of reaction conditions, thereby maximizing the separation efficiency of olefins from their mixtures with paraffins.

  6. Phase transitions in frustrated XY model on a square lattice

    NASA Astrophysics Data System (ADS)

    Qin, M. H.; Chen, X.; Liu, J. M.

    2009-12-01

    We study the phase diagram of a frustrated XY model with a nematic coupling (Δ) on the square lattice by means of Monte Carlo simulation. Besides the conventional magnetic-chiral phase, the phase diagram shows an obvious region in which the magnetism is algebraically ordered but the chirality remains disordered. In addition, in the large Δ region, a nematic-chiral phase without magnetic order is identified, which is similar to the phase found in the frustrated XY model on triangular lattice [J. H. Park, S. Onoda, N. Nagaosa, and J. H. Han, Phys. Rev. Lett. 101, 167202 (2008)

  7. Frustration of crystallisation by a liquid-crystal phase.

    PubMed

    Syme, Christopher D; Mosses, Joanna; González-Jiménez, Mario; Shebanova, Olga; Walton, Finlay; Wynne, Klaas

    2017-02-17

    Frustration of crystallisation by locally favoured structures is critically important in linking the phenomena of supercooling, glass formation, and liquid-liquid transitions. Here we show that the putative liquid-liquid transition in n-butanol is in fact caused by geometric frustration associated with an isotropic to rippled lamellar liquid-crystal transition. Liquid-crystal phases are generally regarded as being "in between" the liquid and the crystalline state. In contrast, the liquid-crystal phase in supercooled n-butanol is found to inhibit transformation to the crystal. The observed frustrated phase is a template for similar ordering in other liquids and likely to play an important role in supercooling and liquid-liquid transitions in many other molecular liquids.

  8. Frustration of crystallisation by a liquid–crystal phase

    PubMed Central

    Syme, Christopher D.; Mosses, Joanna; González-Jiménez, Mario; Shebanova, Olga; Walton, Finlay; Wynne, Klaas

    2017-01-01

    Frustration of crystallisation by locally favoured structures is critically important in linking the phenomena of supercooling, glass formation, and liquid-liquid transitions. Here we show that the putative liquid-liquid transition in n-butanol is in fact caused by geometric frustration associated with an isotropic to rippled lamellar liquid-crystal transition. Liquid-crystal phases are generally regarded as being “in between” the liquid and the crystalline state. In contrast, the liquid-crystal phase in supercooled n-butanol is found to inhibit transformation to the crystal. The observed frustrated phase is a template for similar ordering in other liquids and likely to play an important role in supercooling and liquid-liquid transitions in many other molecular liquids. PMID:28209972

  9. Frustration of crystallisation by a liquid–crystal phase

    NASA Astrophysics Data System (ADS)

    Syme, Christopher D.; Mosses, Joanna; González-Jiménez, Mario; Shebanova, Olga; Walton, Finlay; Wynne, Klaas

    2017-02-01

    Frustration of crystallisation by locally favoured structures is critically important in linking the phenomena of supercooling, glass formation, and liquid-liquid transitions. Here we show that the putative liquid-liquid transition in n-butanol is in fact caused by geometric frustration associated with an isotropic to rippled lamellar liquid-crystal transition. Liquid-crystal phases are generally regarded as being “in between” the liquid and the crystalline state. In contrast, the liquid-crystal phase in supercooled n-butanol is found to inhibit transformation to the crystal. The observed frustrated phase is a template for similar ordering in other liquids and likely to play an important role in supercooling and liquid-liquid transitions in many other molecular liquids.

  10. Phase Transitions in Frustrated Vector Spin Systems: Numerical Studies

    NASA Astrophysics Data System (ADS)

    Loison, Damien

    The following sections are included: * Introduction * Breakdown of symmetry * Symmetry in the high-temperature region * Breakdown of symmetry for ferromagnetic systems * Breakdown of symmetry for frustrated systems * Stacked triangular antiferromagnetic lattices * bct helimagnets * Stacked J1-J2 square lattices * The simple cubic J1-J2 lattice * J1-J2-J3 lattice * Villain lattice and fully frustrated simple cubic lattice * Face-centered cubic lattice (fcc) * Hexagonal-close-packed lattice (hcp) * Pyrochlores * Other lattices * STAR lattices * Dihedral lattices VN,2 * Right-handed trihedral lattices V3,3 * P-hedral lattices VN,P * Ising and Potts-VN,1 model * Ising and Potts-N,2 model * Landau-Ginzburg model * Cubic term in Hamiltonian * Summary * Phase transitions between two and four dimensions: 2 < d ≤ 4 * O(N)/O(N - 2) breakdown of symmetry * Fixed points * MCRG and first-order transition * Complex fixed point or minimum in the flow * Experiment * Value of Nc * Phase diagram (N,d) * Renormalization-group expansions * Short historical review * Relations with the Potts model * O(N)/O(N - P) breakdown of symmetry for d = 3 * Z2 ⊗ SO(N)/SO(N - 1) breakdown of symmetry for d = 3 * Z3 ⊗ SO(N)/SO(N - 1) breakdown of symmetry for d = 3 * Zq ⊗ O(N)/O(N - 2) and other breakdown of symmetry in d = 3 * Conclusion * O(N) frustrated vector spins in d = 2 * Introduction * Non frustrated XY spin systems * Frustrated XY spin systems: Z2 ⊗ SO(2) * Frustrated XY spin systems: Z3 ⊗ SO(2) * Frustrated XY spin systems: Z2 ⊗ Z2 ⊗ SO(2) and Z3 ⊗ Z2 ⊗ SO(2) * Frustrated Heisenberg spin systems: SO(3) * Frustrated Heisenberg spin systems: Z2 ⊗ SO(3), Z3 ⊗ SO(3) … * Topological defects for N ≥ 4 * General conclusions * Acknowledgments * Appendix A: Monte Carlo simulation * Appendix B: Renormalization group: Landau-Ginzburg theory, expansions in fixed dimension d = 3 and for d = 4 - ɛ and its implications for experiments * References

  11. Thermodynamic phase transitions in a frustrated magnetic metamaterial.

    PubMed

    Anghinolfi, L; Luetkens, H; Perron, J; Flokstra, M G; Sendetskyi, O; Suter, A; Prokscha, T; Derlet, P M; Lee, S L; Heyderman, L J

    2015-09-21

    Materials with interacting magnetic degrees of freedom display a rich variety of magnetic behaviour that can lead to novel collective equilibrium and out-of-equilibrium phenomena. In equilibrium, thermodynamic phases appear with the associated phase transitions providing a characteristic signature of the underlying collective behaviour. Here we create a thermally active artificial kagome spin ice that is made up of a large array of dipolar interacting nanomagnets and undergoes phase transitions predicted by microscopic theory. We use low energy muon spectroscopy to probe the dynamic behaviour of the interacting nanomagnets and observe peaks in the muon relaxation rate that can be identified with the critical temperatures of the predicted phase transitions. This provides experimental evidence that a frustrated magnetic metamaterial can be engineered to admit thermodynamic phases.

  12. Evolutionary design of non-frustrated networks of phase-repulsive oscillators

    PubMed Central

    Levnajić, Zoran

    2012-01-01

    Evolutionary optimisation algorithm is employed to design networks of phase-repulsive oscillators that achieve an anti-phase synchronised state. By introducing the link frustration, the evolutionary process is implemented by rewiring the links with probability proportional to their frustration, until the final network displaying a unique non-frustrated dynamical state is reached. Resulting networks are bipartite and with zero clustering. In addition, the designed non-frustrated anti-phase synchronised networks display a clear topological scale. This contrasts usually studied cases of networks with phase-attractive dynamics, whose performance towards full synchronisation is typically enhanced by the presence of a topological hierarchy. PMID:23243494

  13. Entropy Evolution in the Magnetic Phases of Partially Frustrated CePdAl

    NASA Astrophysics Data System (ADS)

    Lucas, S.; Grube, K.; Huang, C.-L.; Sakai, A.; Wunderlich, S.; Green, E. L.; Wosnitza, J.; Fritsch, V.; Gegenwart, P.; Stockert, O.; v. Löhneysen, H.

    2017-03-01

    In the heavy-fermion metal CePdAl, long-range antiferromagnetic order coexists with geometric frustration of one-third of the Ce moments. At low temperatures, the Kondo effect tends to screen the frustrated moments. We use magnetic fields B to suppress the Kondo screening and study the magnetic phase diagram and the evolution of the entropy with B employing thermodynamic probes. We estimate the frustration by introducing a definition of the frustration parameter based on the enhanced entropy, a fundamental feature of frustrated systems. In the field range where the Kondo screening is suppressed, the liberated moments tend to maximize the magnetic entropy and strongly enhance the frustration. Based on our experiments, this field range may be a promising candidate to search for a quantum spin liquid.

  14. Coupling among three chemical oscillators: Synchronization, phase death, and frustration

    NASA Astrophysics Data System (ADS)

    Yoshimoto, Minoru; Yoshikawa, Kenichi; Mori, Yoshihito

    1993-02-01

    Various modes in three coupled chemical oscillators in a triangular arrangement were observed. As a well-defined nonlinear oscillator, the Belousov-Zhabotinsky reaction was studied in a continuous-flow stirred tank reactor (CSTR). Coupling among CSTR's was performed by mass exchange. The coupling strength was quantitatively controlled by changing the flow rate of reacting solutions among the three CSTR's using peristaltic pumps between each pair of the reactors. As a key parameter to control the model of coupling, we changed the symmetry of the interaction between the oscillators. In the case of the symmetric coupling, a quasiperiodic state or a biperiodic mode, an all-death mode and two kinds of synchronized modes appeared, depending on the coupling strength. On the other hand, under the asymmetric coupling, a quasiperiodic state or a biperiodic mode, an all death mode and four kinds of synchronized modes appeared. Those modes have been discussed in relation to the idea of ``frustration'' in the Ising spin system, where the three-phase mode appears as a transition from the Ising spin system to the XY spin system.

  15. Process for phase separation

    DOEpatents

    Comolli, Alfred G.

    1979-01-01

    This invention provides a continuous process for separating a gaseous phase from a hydrocarbon liquid containing carbonaceous particulates and gases. The liquid is fed to a cylindrical separator, with the gaseous phase being removed therefrom as an overhead product, whereas the hydrocarbon liquid and the particulates are withdrawn as a bottoms product. By feeding the liquid tangentially to the separator and maintaining a particulate-liquid slurry downward velocity of from about 0.01 to about 0.25 fps in the separator, a total solids weight percent in the slurry of from about 0.1 to about 30%, a slurry temperature of from about 550.degree. to about 900.degree. F., a slurry residence time in the separator of from about 30 to about 360 seconds, and a length/diameter ratio for the separator of from about 20/1 to about 50/1, so that the characterization factor, .alpha., defined as ##STR1## DOES NOT EXCEED ABOUT 48 (.degree.R sec.sup.2)/ft, the deposit of carbonaceous materials on the interior surface of the separator may be substantially eliminated.

  16. Quantum phase diagrams and phase transitions in frustrated two-dimensional Heisenberg models

    NASA Astrophysics Data System (ADS)

    Sheng, Donna

    2014-03-01

    The quantum spin liquid is an emergent state of matter, which has attracted a lot of recent attention. I will review recent numerical progress based on the density matrix renormalization calculations in identifying gapped spin liquid in two-dimensional frustrated spin systems. I will first focus on extended model with Heisenberg exchange couplings on kagome lattice and demonstrate a topological state with fractionalized spinon and emergent gauge field clearly shown in numerical simulations. I will present concrete results on the quantum phase diagram of the extended kagome Heisenberg model, and compare that with the phase diagrams of the square and honeycomb lattice models with the dominant plaquette valence bond phase in nonmagnetic region. I will discuss numerical effort and theoretical challenge in fully pinning down the nature of the gapped topological phase, and also the nature of the quantum phase transitions in these Heisenberg systems. The research was supported by the National Science Foundation grant DMR-0906816.

  17. Competing spin phases in geometrically frustrated magnetic molecules.

    PubMed

    Schröder, Christian; Nojiri, Hiroyuki; Schnack, Jürgen; Hage, Peter; Luban, Marshall; Kögerler, Paul

    2005-01-14

    We identify a class of zero-dimensional classical and quantum Heisenberg spin systems exhibiting anomalous behavior in an external magnetic field B similar to that found for the geometrically frustrated kagome lattice of classical spins. Our calculations for the isotropic Heisenberg model show the emergence of a pronounced minimum in the differential susceptibility dM/dB at B(sat)/3 as the temperature T is raised from 0 K for structures based on corner-sharing triangles, specifically the octahedron, cuboctahedron, and icosidodecahedron. As the first experimental evidence we note that the giant Keplerate magnetic molecule {Mo(72)Fe(30)} (Fe(3+) ions on the 30 vertices of an icosidodecahedron) exhibits this behavior. For low T when B approximately B(sat)/3 two competing families of spin configurations exist of which one behaves magnetically "stiff" leading to a reduction of dM/dB.

  18. Microgravity Passive Phase Separator

    NASA Technical Reports Server (NTRS)

    Paragano, Matthew; Indoe, William; Darmetko, Jeffrey

    2012-01-01

    A new invention disclosure discusses a structure and process for separating gas from liquids in microgravity. The Microgravity Passive Phase Separator consists of two concentric, pleated, woven stainless- steel screens (25-micrometer nominal pore) with an axial inlet, and an annular outlet between both screens (see figure). Water enters at one end of the center screen at high velocity, eventually passing through the inner screen and out through the annular exit. As gas is introduced into the flow stream, the drag force exerted on the bubble pushes it downstream until flow stagnation or until it reaches an equilibrium point between the surface tension holding bubble to the screen and the drag force. Gas bubbles of a given size will form a front that is moved further down the length of the inner screen with increasing velocity. As more bubbles are added, the front location will remain fixed, but additional bubbles will move to the end of the unit, eventually coming to rest in the large cavity between the unit housing and the outer screen (storage area). Owing to the small size of the pores and the hydrophilic nature of the screen material, gas does not pass through the screen and is retained within the unit for emptying during ground processing. If debris is picked up on the screen, the area closest to the inlet will become clogged, so high-velocity flow will persist farther down the length of the center screen, pushing the bubble front further from the inlet of the inner screen. It is desired to keep the velocity high enough so that, for any bubble size, an area of clean screen exists between the bubbles and the debris. The primary benefits of this innovation are the lack of any need for additional power, strip gas, or location for venting the separated gas. As the unit contains no membrane, the transport fluid will not be lost due to evaporation in the process of gas separation. Separation is performed with relatively low pressure drop based on the large surface

  19. Frustrated smectic liquid crystalline phases in lactic acid derivatives

    NASA Astrophysics Data System (ADS)

    Glogarová, M.; Novotná, V.

    2016-08-01

    We have prepared and studied a series of compounds with different types of molecular core and lactate unit in the chiral terminal chain. We draw a survey and comparison of their mesomorphic properties with respect to the occurrence of twist grain boundary (TGB) phases. The materials exhibit extremely wide TGBA phase more than 60K broad, unique TGBA-TGBC-SmC*-SmCA* phase sequence and unique re-entrant TGBA phase below the SmA phase. TGB phases have been induced in binary mixtures of molecules with different molecular shape and chirality (chiral lactic acid derivative and non-chiral hockey-stick mesogen). Unique effect is observed for compounds with TGBA phase, where the applied electric field transforms the planar texture into the homeotropic one, homogeneously dark in crossed polarizers. The process is analogy of the Frederiks transition so far known only for nematics. This effect, changing the bright state to the dark one, is promising for applications.

  20. Role-separating ordering in social dilemmas controlled by topological frustration

    NASA Astrophysics Data System (ADS)

    Amaral, Marco A.; Perc, Matjaž; Wardil, Lucas; Szolnoki, Attila; da Silva Júnior, Elton J.; da Silva, Jafferson K. L.

    2017-03-01

    ``Three is a crowd" is an old proverb that applies as much to social interactions as it does to frustrated configurations in statistical physics models. Accordingly, social relations within a triangle deserve special attention. With this motivation, we explore the impact of topological frustration on the evolutionary dynamics of the snowdrift game on a triangular lattice. This topology provides an irreconcilable frustration, which prevents anticoordination of competing strategies that would be needed for an optimal outcome of the game. By using different strategy updating protocols, we observe complex spatial patterns in dependence on payoff values that are reminiscent to a honeycomb-like organization, which helps to minimize the negative consequence of the topological frustration. We relate the emergence of these patterns to the microscopic dynamics of the evolutionary process, both by means of mean-field approximations and Monte Carlo simulations. For comparison, we also consider the same evolutionary dynamics on the square lattice, where of course the topological frustration is absent. However, with the deletion of diagonal links of the triangular lattice, we can gradually bridge the gap to the square lattice. Interestingly, in this case the level of cooperation in the system is a direct indicator of the level of topological frustration, thus providing a method to determine frustration levels in an arbitrary interaction network.

  1. Frustrated polaritons

    NASA Astrophysics Data System (ADS)

    Schmidt, Sebastian

    2016-07-01

    Artificially engineered light-matter systems constitute a novel, versatile architecture for the quantum simulation of driven, dissipative phase transitions and non-equilibrium quantum many-body systems. Here, we discuss recent experimental as well as theoretical works on the simulation of geometrical frustration in interacting photonic systems out of equilibrium. In particular, we review two recent discoveries at the interface of quantum optics and condensed matter physics: (i) the experimental achievement of Bosonic condensation into a flat energy band and (ii) the theoretical prediction of crystalline phases of light in a frustrated qubit-cavity array. We show that this new line of research leads to novel and unique tools for the experimental investigation of frustrated systems and holds the potential to create new phases of light and matter with interesting spatial structure.

  2. Microcellular foams via phase separation

    SciTech Connect

    Young, A.T.

    1985-01-01

    A study of wide variety of processes for making plastic foams shows that phase separation processes for polymers from solutions offers the most viable methods for obtaining rigid plastic foams which met the physical requirements for fusion target designs. Four general phase separation methods have been shown to give polymer foams with densities less than 0.1 g/cm/sup 3/ and cell sizes of 30..mu..m or less. These methods involve the utilization of non-solvent, chemical or thermal cooling processes to achieve a controlled phase separation wherein either two distinct phases are obtained where the polymer phase is a continuous phase or two bicontinuous phases are obtained where both the polymer and solvent are interpenetrating, continuous, labyrinthine phases. Subsequent removal of the solvent gives the final foam structure.

  3. Phase and vortex correlations in superconducting Josephson-junction arrays at irrational magnetic frustration.

    PubMed

    Granato, Enzo

    2008-07-11

    Phase coherence and vortex order in a Josephson-junction array at irrational frustration are studied by extensive Monte Carlo simulations using the parallel-tempering method. A scaling analysis of the correlation length of phase variables in the full equilibrated system shows that the critical temperature vanishes with a power-law divergent correlation length and critical exponent nuph, in agreement with recent results from resistivity scaling analysis. A similar scaling analysis for vortex variables reveals a different critical exponent nuv, suggesting that there are two distinct correlation lengths associated with a decoupled zero-temperature phase transition.

  4. Chemical Frustration. A Design Principle for the Discovery of New Complex Alloy and Intermetallic Phases, Final Report

    SciTech Connect

    Fredrickson, Daniel C

    2015-06-23

    Final technical report for "Chemical Frustration: A Design Principle for the Discovery of New Complex Alloy and Intermetallic Phases" funded by the Office of Science through the Materials Chemistry Program of the Office of Basic Energy Sciences.

  5. Nature of the possible magnetic phases in a frustrated hyperkagome iridate

    NASA Astrophysics Data System (ADS)

    Shindou, Ryuichi

    2016-03-01

    Based on the Kitaev-Heisenberg model with Dzyaloshinskii-Moriya (DM) interactions, we studied the nature of possible magnetic phases in the frustrated hyperkagome iridate, Na4Ir3O8 (Na-438). Using Monte Carlo simulation, we showed that the phase diagram is mostly covered by two competing magnetic ordered phases, the Z2 symmetry breaking (SB) phase and the Z6 SB phase, latter of which is stabilized by the classical order by disorder. These two phases are intervened by a first-order phase-transition line with Z8-like symmetry. The critical nature at the Z6 SB ordering temperature is characterized by the three-dimensional X Y universality class, below which U(1) to Z6 crossover phenomenon appears: the Z6 spin anisotropy becomes irrelevant in a length scale shorter than a crossover length Λ* while it becomes relevant otherwise. A possible phenomenology of polycrystalline Na-438 is discussed based on this crossover phenomenon.

  6. Random exchange interaction effects on the phase transitions in frustrated classical Heisenberg model

    SciTech Connect

    Li, W. C.; Song, X.; Feng, J. J.; Zeng, M.; Gao, X. S.; Qin, M. H.; Jia, X. T.

    2015-07-07

    In this work, the effects of the random exchange interaction on the phase transitions and phase diagrams of classical frustrated Heisenberg model are investigated by Monte Carlo simulation in order to simulate the chemical doping effect in real materials. It is observed that the antiferromagnetic transitions shift toward low temperature with the increasing magnitude of the random exchange interaction, which can be qualitatively understood from the competitions among local spin states. This study is related to the magnetic properties in the doped iron-based superconductors.

  7. Geometrical aspects of the frustration in the cubic phases of lyotropic liquid crystals.

    PubMed Central

    Anderson, D M; Gruner, S M; Leibler, S

    1988-01-01

    Bicontinuous cubic phases, composed of bilayers arranged in the geometries of periodic minimal surfaces, are found in a variety of different lipid/water systems. It has been suggested recently that these cubic structures arrive as the result of competition between two free-energy terms: the curvature energy of each monolayer and the stretching energy of the lipid chains. This scenario, closely analogous to the one that explains the origin of the hexagonal phases, is investigated here by means of simple geometrical calculations. It is first assumed that the lipid bilayer is of constant thickness and the distribution of the (local) mean curvature of the phospholipid-water interfaces is calculated. Then, assuming the mean curvature of these interfaces is constant, the distribution of the bilayer's thickness is calculated. Both calculations quantify the fact that the two energy terms are frustrated and cannot be satisfied simultaneously. However, the amount of the frustration can be smaller for the cubic phase than for the lamellar and hexagonal structures. Therefore, this phase can appear in the phase diagram between the other two, as observed in many recent experiments. PMID:3399497

  8. Magnetic phase diagram and Mott transition of the half-filled 1/5 -depleted Hubbard model with frustration

    NASA Astrophysics Data System (ADS)

    Yamada, Atsushi

    2014-12-01

    The magnetic properties and Mott transition of the half-filled Hubbard model on the 1/5 -depleted square lattice with frustration are studied at zero temperature by the variational cluster approximation. The (π ,π ) Néel ordering is stable in a wide region of the phase diagram and almost completely veils the nonmagnetic Mott transition for the nonfrustrated case. However, (π ,π ) Néel ordering is severely suppressed by the frustration, and even with moderate frustrations the nonmagnetic Mott transition takes place in the range where the intradimer hoppings are larger than the intraplaquette hoppings.

  9. Perspective: Geometrically frustrated assemblies

    NASA Astrophysics Data System (ADS)

    Grason, Gregory M.

    2016-09-01

    This perspective will overview an emerging paradigm for self-organized soft materials, geometrically frustrated assemblies, where interactions between self-assembling elements (e.g., particles, macromolecules, proteins) favor local packing motifs that are incompatible with uniform global order in the assembly. This classification applies to a broad range of material assemblies including self-twisting protein filament bundles, amyloid fibers, chiral smectics and membranes, particle-coated droplets, curved protein shells, and phase-separated lipid vesicles. In assemblies, geometric frustration leads to a host of anomalous structural and thermodynamic properties, including heterogeneous and internally stressed equilibrium structures, self-limiting assembly, and topological defects in the equilibrium assembly structures. The purpose of this perspective is to (1) highlight the unifying principles and consequences of geometric frustration in soft matter assemblies; (2) classify the known distinct modes of frustration and review corresponding experimental examples; and (3) describe outstanding questions not yet addressed about the unique properties and behaviors of this broad class of systems.

  10. Phase transition of geometrically frustrated TbNiAl in a magnetic field

    SciTech Connect

    Ehlers, Georg

    2007-01-01

    The phase transitions of the geometrically frustrated antiferromagnet TbNiAl in a magnetic field are studied by means of neutron powder diffraction, ac susceptibility, and muon spin relaxation ({mu}SR) measurements. Neutron powder diffraction reveals that, in addition to antiferromagnetic order, ferromagnetic order is induced in a field as low as B{approx}0.02T . At higher fields, ferromagnetic and antiferromagnetic order coexist in different domains in the sample, and the domain balance depends on both magnetic field and temperature. Antiferromagnetic Bragg reflections are observed below a Neel temperature of T{sub N}=47K which is independent of the field. Ferromagnetic Bragg peaks are observed below a field-dependent Curie temperature which increases from {Tc}=52K at B=0.2T to {Tc}=70K at B=5T . Both phase transitions are concurrently observed in ac susceptibility and {mu}SR measurements.

  11. Effect of quantum phase transition on spin transport in the spatially frustrated Heisenberg model

    NASA Astrophysics Data System (ADS)

    Lima, L. S.

    2017-03-01

    We have used the Schwinger's boson theory to study the spin transport in the anisotropic two-dimensional spatially frustrated Heisenberg antiferromagnetic model in the square lattice. Our results show a sudden change in the AC spin conductivity σreg (ω) in the quantum phase transition point, where we have the gap of the system going to zero at critical point Dc=0. We have found a sudden change for a superconductor state in the DC limit ω → 0 independent of the value of the Drude's weight found in the quantum phase transition point. Away from it, we have obtained that the behavior of the spin conductivity changes for single peak at ω =ωp and in this case, σreg (ω) goes to zero in small ω and large ω limits.

  12. Spin-stripe phase in a frustrated zigzag spin-1/2 chain

    PubMed Central

    Pregelj, M.; Zorko, A.; Zaharko, O.; Nojiri, H.; Berger, H.; Chapon, L. C.; Arčon, D.

    2015-01-01

    Motifs of periodic modulations are encountered in a variety of natural systems, where at least two rival states are present. In strongly correlated electron systems, such behaviour has typically been associated with competition between short- and long-range interactions, for example, between exchange and dipole–dipole interactions in the case of ferromagnetic thin films. Here we show that spin-stripe textures may develop also in antiferromagnets, where long-range dipole–dipole magnetic interactions are absent. A comprehensive analysis of magnetic susceptibility, high-field magnetization, specific heat and neutron diffraction measurements unveils β-TeVO4 as a nearly perfect realization of a frustrated (zigzag) ferromagnetic spin-1/2 chain. Notably, a narrow spin-stripe phase develops at elevated magnetic fields due to weak frustrated short-range interchain exchange interactions, possibly assisted by the symmetry-allowed electric polarization. This concept provides an alternative route for the stripe formation in strongly correlated electron systems and may help understanding of other widespread, yet still elusive, stripe-related phenomena. PMID:26068618

  13. Novel phases in a square-lattice frustrated ferromagnet : 1/3 -magnetization plateau, helicoidal spin liquid, and vortex crystal

    NASA Astrophysics Data System (ADS)

    Seabra, Luis; Sindzingre, Philippe; Momoi, Tsutomu; Shannon, Nic

    2016-02-01

    A large part of the interest in magnets with frustrated antiferromagnetic interactions comes from the many new phases found in applied magnetic field. In this article, we explore some of the new phases which arise in a model with frustrated ferromagnetic interactions, the J1-J2-J3 Heisenberg model on a square lattice. Using a combination of classical Monte Carlo simulation and spin-wave theory, we uncover behavior reminiscent of some widely studied frustrated antiferromagnets, but with a number of new twists. We first demonstrate that, for a suitable choice of parameters, the phase diagram as a function of magnetic field and temperature is nearly identical to that of the Heisenberg antiferromagnet on a triangular lattice, including the celebrated 1 /3 -magnetization plateau. We then examine how this phase diagram changes when the model is tuned to a point where the classical ground state is highly degenerate. In this case, two new phases emerge: a classical, finite-temperature spin liquid, characterized by a "ring" in the spin structure factor S (q ) ; and a vortex crystal, a multiple-Q state with finite magnetization, which can be viewed as an ordered lattice of magnetic vortices. All of these new phases persist for a wide range of magnetic fields. We discuss the relationship between these results and published studies of frustrated antiferromagnets, together with some of the materials where these new phases might be observed in experiment.

  14. One-dimensional frustrated plaquette compass model: Nematic phase and spontaneous multimerization

    NASA Astrophysics Data System (ADS)

    Brzezicki, Wojciech; Oleś, Andrzej M.

    2016-06-01

    We introduce a one-dimensional (1D) pseudospin model on a ladder where the Ising interactions along the legs and along the rungs alternate between XiXi +1 and ZiZi +1 for even/odd bond (rung). We include also the next-nearest-neighbor Ising interactions on plaquettes' diagonals that alternate in such a way that a model where only leg interactions are switched on is equivalent to the one when only the diagonal ones are present. Thus in the absence of rung interactions the model can interpolate between two 1D compass models. The model possesses local symmetries which are the parities within each 2 ×2 cell (plaquette) of the ladder. We find that for different values of the interaction it can realize ground states that differ by the patterns formed by these local parities. By exact diagonalization we derive detailed phase diagrams for small systems of L =4 , 6, and 8 plaquettes, and use next L =12 to identify generic phases that appear in larger systems as well. Among them we find a nematic phase with macroscopic degeneracy when the leg and diagonal interactions are equal and the rung interactions are larger than a critical value. By performing a perturbative expansion around this phase we find indeed a very complex competition around the nematic phase which has to do with releasing frustration in this range of parameters. The nematic phase is similar to the one found in the two-dimensional compass model. For particular parameters the low-energy sector of the present plaquette model reduces to a 1D compass model with spins S =1 which suggests that it realizes peculiar crossovers within the class of compass models. Finally, we show that the model can realize phases with broken translation invariance which can be either dimerized, trimerized, etc., or completely disordered and highly entangled in a well identified window of the phase diagram.

  15. Vapors-liquid phase separator

    NASA Astrophysics Data System (ADS)

    Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

    1980-10-01

    The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

  16. Competing Ferri- and Antiferromagnetic Phases in Geometrically Frustrated LuFe2O4

    SciTech Connect

    De Groot, J.; Marty, Karol J; Lumsden, Mark D; Christianson, Andrew D; Nagler, Stephen E; Adiga, Shilpa; Borghols, Wouter; Schmalzl, Karin; Yamani, Z.; Bland, S. R.; de Souza, R.; Staub, U.; Schweika, Werner; Su, Y.; Angst, Manuel

    2012-01-01

    We present a detailed study of magnetism in LuFe2O4, combining magnetization measurements with neutron and soft x-ray diffraction. The magnetic phase diagram in the vicinity of TN involves a metamagnetic transition separating an antiferro- and a ferrimagnetic phase. For both phases the spin structure is refined by neutron diffraction. Observed diffuse magnetic scattering far above TN is explained in terms of near degeneracy of the magnetic phases.

  17. First-order phase transitions in spinor Bose gases and frustrated magnets

    NASA Astrophysics Data System (ADS)

    Debelhoir, T.; Dupuis, N.

    2016-11-01

    We show that phase transitions in spin-1 Bose gases and stacked triangular Heisenberg antiferromagnets—an example of frustrated magnets with competing interactions—are described by the same Landau-Ginzburg-Wilson Hamiltonian with O (3 )×O (2 ) symmetry. In agreement with previous nonperturbative-renormalization-group studies of the three-dimensional O (3 )×O (2 ) model, we find that the transition from the normal phase to the superfluid ferromagnetic phase in a spin-1 Bose gas is weakly first order and shows pseudoscaling behavior. The (nonuniversal) pseudoscaling exponent ν is fully determined by the scattering lengths a0 and a2. We provide estimates of ν in 87Rb,41K, and 7Li atom gases which can be tested experimentally. We argue that pseudoscaling comes from either a crossover phenomenon due to proximity of the O(6) Wilson-Fisher fixed point (87Rb and 41K) or the existence of two unphysical fixed points (with complex coordinates) which slow down the RG flow (7Li). These unphysical fixed points are a remnant of the chiral and antichiral fixed points that exist in the O (N )×O (2 ) model when N is larger than Nc≃5.3 (the transition being then second order and controlled by the chiral fixed point). Finally, we discuss a O (2 )×O (2 ) lattice model and show that our results, even though we find the transition to be first order, are compatible with Monte Carlo simulations yielding an apparent second-order transition.

  18. Collective dynamics of time-delay-coupled phase oscillators in a frustrated geometry

    NASA Astrophysics Data System (ADS)

    Thakur, Bhumika; Sharma, Devendra; Sen, Abhijit; Johnston, George L.

    2017-01-01

    We study the effect of time delay on the dynamics of a system of repulsively coupled nonlinear oscillators that are configured as a geometrically frustrated network. In the absence of time delay, frustrated systems are known to possess a high degree of multistability among a large number of coexisting collective states except for the fully synchronized state that is normally obtained for attractively coupled systems. Time delay in the coupling is found to remove this constraint and to lead to such a synchronized ground state over a range of parameter values. A quantitative study of the variation of frustration in a system with the amount of time delay has been made and a universal scaling behavior is found. The variation in frustration as a function of the product of time delay and the collective frequency of the system is seen to lie on a characteristic curve that is common for all natural frequencies of the identical oscillators and coupling strengths. Thus time delay can be used as a tuning parameter to control the amount of frustration in a system and thereby influence its collective behavior. Our results can be of potential use in a host of practical applications in physical and biological systems in which frustrated configurations and time delay are known to coexist.

  19. Colossal negative thermal expansion induced by magnetic phase competition on frustrated lattices in Laves phase compound (Hf,Ta)Fe2

    NASA Astrophysics Data System (ADS)

    Li, B.; Luo, X. H.; Wang, H.; Ren, W. J.; Yano, S.; Wang, C.-W.; Gardner, J. S.; Liss, K.-D.; Miao, P.; Lee, S.-H.; Kamiyama, T.; Wu, R. Q.; Kawakita, Y.; Zhang, Z. D.

    2016-06-01

    Competition between ferromagnetic and antiferromagnetic phases on frustrated lattices in hexagonal Laves phase compound Hf0.86Ta0.14Fe2 is investigated by using neutron diffraction as a function of temperature and magnetic fields and density-functional-theory calculations. At 325 K, the compound orders into the 120° frustrated antiferromagnetic state with a well-reduced magnetic moment, and an in-plane lattice contraction simultaneously sets in. With further cooling down, however, the accumulated distortion in turn destabilizes this susceptible frustrated structure. The frustration is completely relieved at 255 K when the first-order transition to the ferromagnetic state takes place, where a colossal negative volumetric thermal expansion, -123 ×10-6 /K, is obtained. Meanwhile, the antiferromagnetic state can be suppressed by few-tesla magnetic fields, which results in a colossal positive magnetostriction. Such delicate competition is attributed to the giant magnetic fluctuation inherent in the frustrated antiferromagnetic state. Therefore, the magnetoelastic instability is approached even under a small perturbation.

  20. Characterization of Topological Phases of Spin-1/2 Frustrated Ferromagnetic-Antiferromagnetic Alternating Heisenberg Chains by Entanglement Spectrum

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo

    2016-02-01

    The topological classification of a series of frustration-induced spin-gap phases in the spin-1/2 ferromagnetic-antiferromagnetic alternating Heisenberg chain with next-nearest-neighbour interaction reported in J. Phys. Soc. Jpn. 82, 064703 (2013) is confirmed using two kinds of entanglement spectra defined by different divisions of the whole chain. For the numerical calculation, the iDMRG method is used. The results are consistent with the valence bond solid picture proposed in the previous paper.

  1. Two-Phase Flow Separator Investigation

    NASA Video Gallery

    The goal of the Two-Phase Flow Separator investigation is to help increase understanding of how to separate gases and liquids in microgravity. Many systems on the space station contain both liquids...

  2. Giant barocaloric effect enhanced by the frustration of the antiferromagnetic phase in Mn3GaN

    NASA Astrophysics Data System (ADS)

    Matsunami, Daichi; Fujita, Asaya; Takenaka, Koshi; Kano, Mika

    2015-01-01

    First-order phase transitions are accompanied by a latent heat. Consequently, manipulating them by means of an external field causes a caloric effect. Although transitions from antiferromagnetic to paramagnetic states are not controlled by a magnetic field, a large barocaloric effect is expected when strong cross-correlations between the volume and magnetic order occur. Here we examine how geometric frustration in itinerant antiferromagnetic compounds can enhance the barocaloric effect. We study the thermodynamic behaviour of the frustrated antiferromagnet Mn3GaN, and report an entropy change of 22.3 J kg-1 K-1 that is concomitant with a hydrostatic pressure change of 139 MPa. Furthermore, the calculated value of the adiabatic temperature change reaches 5 K by depressurization of 93 MPa. The giant barocaloric effect in Mn3GaN is caused by a frustration-driven enhancement of the ratio of volume change against the pressure coefficient of the Néel temperature. This mechanism for enhancing the barocaloric effect can form the basis for a new class of materials for solid-state refrigerants.

  3. Chaotic background phase matching signal separation method

    NASA Astrophysics Data System (ADS)

    Peng, Wu; Hui, Xia; Chen, Wang

    2016-07-01

    Aiming at the problem of separating the useful signal in the chaos background and using the phase matching method, the signal can be extracted effectively from the chaotic background. In this method, the chaotic background is not estimated with phase reconstruction and the geometric analysis of phase space is not required. Through the separation Simulation of the sinusoidal signal in the chaos background and the separation degree analysis, the low signal to noise ratio of the signal in the chaos background can be effectively separated. The effect of removing the chaotic background noise is obvious.

  4. Binary Colloidal Alloy Test-5: Phase Separation

    NASA Technical Reports Server (NTRS)

    Lynch, Matthew; Weitz, David A.; Lu, Peter J.

    2008-01-01

    The Binary Colloidal Alloy Test - 5: Phase Separation (BCAT-5-PhaseSep) experiment will photograph initially randomized colloidal samples onboard the ISS to determine their resulting structure over time. This allows the scientists to capture the kinetics (evolution) of their samples, as well as the final equilibrium state of each sample. BCAT-5-PhaseSep studies collapse (phase separation rates that impact product shelf-life); in microgravity the physics of collapse is not masked by being reduced to a simple top and bottom phase as it is on Earth.

  5. Study Of Phase Separation In Glass

    NASA Technical Reports Server (NTRS)

    Neilson, George F.; Weinberg, Michael C.; Smith, Gary L.

    1989-01-01

    Report describes an experimental study of effect of hydroxide content on phase separation in soda/silica glasses. Ordinary and gel glasses melted at 1,565 degree C, and melts stirred periodically. "Wet" glasses produced by passing bubbles of N2 saturated with water through melts; "dry" glasses prepared in similar manner, except N2 dried before passage through melts. Analyses of compositions of glasses performed by atomic-absorption and index-of-refraction measurements. Authors conclude hydroxide speeds up phase separation, regardless of method (gel or ordinary) by which glass prepared. Eventually helps material scientists to find ways to control morphology of phase separation.

  6. Vapor-liquid phase separator studies

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Lee, J. M.; Kim, Y. I.; Hepler, W. A.; Frederking, T. H. K.

    1983-01-01

    Porous plugs serve as both entropy rejection devices and phase separation components separating the vapor phase on the downstream side from liquid Helium 2 upstream. The liquid upstream is the cryo-reservoir fluid needed for equipment cooling by means of Helium 2, i.e Helium-4 below its lambda temperature in near-saturated states. The topics outlined are characteristic lengths, transport equations and plug results.

  7. Gas-Liquid Flows and Phase Separation

    NASA Technical Reports Server (NTRS)

    McQuillen, John

    2004-01-01

    Common issues for space system designers include:Ability to Verify Performance in Normal Gravity prior to Deployment; System Stability; Phase Accumulation & Shedding; Phase Separation; Flow Distribution through Tees & Manifolds Boiling Crisis; Heat Transfer Coefficient; and Pressure Drop.The report concludes:Guidance similar to "A design that operates in a single phase is less complex than a design that has two-phase flow" is not always true considering the amount of effort spent on pressurizing, subcooling and phase separators to ensure single phase operation. While there is still much to learn about two-phase flow in reduced gravity, we have a good start. Focus now needs to be directed more towards system level problems .

  8. Phase Separation in Solutions of Monoclonal Antibodies

    NASA Astrophysics Data System (ADS)

    Benedek, George; Wang, Ying; Lomakin, Aleksey; Latypov, Ramil

    2012-02-01

    We report the observation of liquid-liquid phase separation (LLPS) in a solution of humanized monoclonal antibodies, IgG2, and the effects of human serum albumin, a major blood protein, on this phase separation. We find a significant reduction of phase separation temperature in the presence of albumin, and a preferential partitioning of the albumin into the antibody-rich phase. We provide a general thermodynamic analysis of the antibody-albumin mixture phase diagram and relate its features to the magnitude of the effective inter-protein interactions. Our analysis suggests that additives (HSA in this report), which have moderate attraction with antibody molecules, may be used to forestall undesirable protein condensation in antibody solutions. Our findings are relevant to understanding the stability of pharmaceutical solutions of antibodies and the mechanisms of cryoglobulinemia.

  9. Phase separations in a copolymer copolymer mixture

    NASA Astrophysics Data System (ADS)

    Zhang, Jin-Jun; Jin, Guojun; Ma, Yuqiang

    2006-01-01

    We propose a three-order-parameter model to study the phase separations in a diblock copolymer-diblock copolymer mixture. The cell dynamical simulations provide rich information about the phase evolution and structural formation, especially the appearance of onion-rings. The parametric dependence and physical reason for the domain growth of onion-rings are discussed.

  10. Charge regularization in phase separating polyelectrolyte solutions.

    PubMed

    Muthukumar, M; Hua, Jing; Kundagrami, Arindam

    2010-02-28

    Theoretical investigations of phase separation in polyelectrolyte solutions have so far assumed that the effective charge of the polyelectrolyte chains is fixed. The ability of the polyelectrolyte chains to self-regulate their effective charge due to the self-consistent coupling between ionization equilibrium and polymer conformations, depending on the dielectric constant, temperature, and polymer concentration, affects the critical phenomena and phase transitions drastically. By considering salt-free polyelectrolyte solutions, we show that the daughter phases have different polymer charges from that of the mother phase. The critical point is also altered significantly by the charge self-regularization of the polymer chains. This work extends the progress made so far in the theory of phase separation of strong polyelectrolyte solutions to a higher level of understanding by considering chains which can self-regulate their charge.

  11. Magnetoelastic coupling within a Landau model of phase transitions: Application to the frustrated triangular antiferromagnet CsNiCl3

    NASA Astrophysics Data System (ADS)

    Quirion, G.; Han, X.; Plumer, M. L.

    2011-07-01

    A model Landau free energy is proposed in order to describe elastic coupling to spin degrees of freedom in systems exhibiting phase transitions which involve long-range magnetic order. Using rigourous symmetry arguments, various interaction terms are derived for magnetic materials with a hexagonal crystal structure. The model is applied to the frustrated triangular antiferromagnet CsNiCl3 and used to analyze and correlate a wide variety of experimental results such as the magnetic phase diagram, magnetization, strains, and elastic constant measurements at low temperatures. Good agreement between the model and the data is obtained for the temperature and magnetic field dependence of C33 and C66 in the vicinity of phase transitions. In particular, the analysis shows that the anomaly observed in the field dependence of C33, close to the spin-flop phase boundary (HSF≃2 T), is dominated by the field dependence of the magnetic susceptibility. It is also found that higher order magnetoelastic coupling terms are required to reproduce the qualitative behavior of the elastic constants in the vicinity of the phase transitions. Our results demonstrate that a straightforward mean-field model which incorporates the correct system symmetries provides a powerful tool for relating complex spin configurations to the elastic and other response functions. The present work also serves to complement and expand our earlier results [G. Quirion , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.97.077202 97, 077202 (2006)].

  12. Frustrated polymer crystal structures

    NASA Astrophysics Data System (ADS)

    Lotz, B.; Strasbourg, 67083

    1997-03-01

    Several crystal structures or polymorphs of chiral or achiral polymers and biopolymers with three fold conformation of the helix have been found to conform to a common and -with one exception(Puterman, M. et al, J. Pol. Sci., Pol. Phys. Ed., 15, 805 (1977))- hitherto unsuspected packing scheme. The trigonal unit-cell contains three isochiral helices; the azimuthal setting of one helix differs significantly from that of the other two, leading to a so-called frustrated packing scheme, in which the environment of conformationally identical helices differs. Two variants of the frustrated scheme are analyzed. Similarities with frustrated two dimensional magnetic systems are underlined. Various examples of frustration in polymer crystallography are illustrated via the elucidation or reinterpretation of crystal phases or polymorphs of polyolefins, polyesters, cellulose derivatives and polypeptides. Structural manifestations (including AFM evidence) and morphological consequences of frustration are presented, which help diagnose the existence of this original packing of polymers.(Work done with L. Cartier, D. Dorset, S. Kopp, T. Okihara, M. Schumacher, W. Stocker.)

  13. Frustrated topological symmetry breaking: Geometrical frustration and anyon condensation

    NASA Astrophysics Data System (ADS)

    Schulz, Marc D.; Burnell, Fiona J.

    2016-10-01

    We study the phase diagram of a topological string-net-type lattice model in the presence of geometrically frustrated interactions. These interactions drive several phase transitions that reduce the topological order, leading to a rich phase diagram including both Abelian (Z2) and non-Abelian (Ising×Ising¯ ) topologically ordered phases, as well as phases with broken translational symmetry. Interestingly, one of these phases simultaneously exhibits (Abelian) topological order and long-ranged order due to translational symmetry breaking, with nontrivial interactions between excitations in the topological order and defects in the long-ranged order. We introduce a variety of effective models, valid along certain lines in the phase diagram, which can be used to characterize both topological and symmetry-breaking order in these phases and in many cases allow us to characterize the phase transitions that separate them. We use exact diagonalization and high-order series expansion to study areas of the phase diagram where these models break down and to approximate the location of the phase boundaries.

  14. Frustrated honeycomb-lattice bilayer quantum antiferromagnet in a magnetic field: Unconventional phase transitions in a two-dimensional isotropic Heisenberg model

    NASA Astrophysics Data System (ADS)

    Krokhmalskii, Taras; Baliha, Vasyl; Derzhko, Oleg; Schulenburg, Jörg; Richter, Johannes

    2017-03-01

    We consider the spin-1/2 antiferromagnetic Heisenberg model on a bilayer honeycomb lattice including interlayer frustration in the presence of an external magnetic field. In the vicinity of the saturation field, we map the low-energy states of this quantum system onto the spatial configurations of hard hexagons on a honeycomb lattice. As a result, we can construct effective classical models (lattice-gas as well as Ising models) on the honeycomb lattice to calculate the properties of the frustrated quantum Heisenberg spin system in the low-temperature regime. We perform classical Monte Carlo simulations for a hard-hexagon model and adopt known results for an Ising model to discuss the finite-temperature order-disorder phase transition that is driven by a magnetic field at low temperatures. We also discuss an effective-model description around the ideal frustration case and find indications for a spin-flop-like transition in the considered isotropic spin model.

  15. Does dynamic vulcanization induce phase separation?

    PubMed

    Abolhasani, Mohammad Mahdi; Zarejousheghani, Fatemeh; Naebe, Minoo; Guo, Qipeng

    2014-08-14

    Immiscible and miscible blends of poly(vinylidene fluoride) (PVDF) and acrylic rubber (ACM) were subjected to dynamic vulcanization to investigate the effect of crosslinking on phase separation. As a result of different processability, mixing torque behavior of miscible and immiscible blends was significantly different from one another. Scanning electron microscopy (SEM) was used to investigate the morphology of the system. After dynamic vulcanization, submicron ACM droplets were observed in the samples near the binodal curve of the system under mixing conditions. Small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC) analysis were used to investigate the effect of dynamic vulcanization on the lamellar structure of the system. It was shown that for samples near the boundary of phase separation, increasing the crosslink density led to a decrease in the lamellar long period (L) as a sign of increment of crosslink density induced phase decomposition. Effects of shear rate on the final morphology of the system were investigated by changing the mixing temperature and by comparing the results of dynamic vulcanization at one phase and two phase regions.

  16. Thermocapillary-Induced Phase Separation with Coalescence

    NASA Technical Reports Server (NTRS)

    Davis, Robert H.

    2003-01-01

    Research has been undertaken on interactions of two or more deformable drops (or bubbles) in a viscous fluid and subject to a temperature, gravitational, or flow field. An asymptotic theory for nearly spherical drops shows that small deformations reduce the coalescence and phase separation rates. Boundary-integral simulations for large deformations show that bubbles experience alignment and enhanced coalescence, whereas more viscous drops may break as a result of hydrodynamic interactions. Experiments for buoyancy motion confirm these observations. Simulations of the sedimentation of many drops show clustering phenomena due to deformations, which lead to enhanced phase separation rates, and simulations of sheared emulsions show that deformations cause a reduction in the effective viscosity.

  17. Simualting the Phase Separated rp-ash

    NASA Astrophysics Data System (ADS)

    Caplan, Matthew; Horowitz, Chuck; Berry, Donald

    2017-01-01

    The composition and phase separation of rp-ash on accreting neutron stars determine the thermal properties of the crust which must be understood to interpret observations of crust cooling in X-ray bursts. In this work, we report on recent large scale molecular dynamics simulations of the outer crust. Using the crust compositions calculated by Mckinven et al. 2016, we study the structure of the crystal that forms, as well as diffusion and thermal properties of the crust.

  18. 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.

  19. 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.

  20. Thermodynamic properties of frustrated arbitrary spin-S J1-J2 quantum Heisenberg antiferromagnet on the body-centered-cubic lattice in random phase approximation

    NASA Astrophysics Data System (ADS)

    Mi, Bin-Zhou

    2016-07-01

    The thermodynamic properties of the frustrated arbitrary spin-S J1-J2 Heisenberg antiferromagnet on the body-centered-cubic lattice for Néel phase are systematically calculated by use of the double-time Green's function method within the random phase approximation (RPA). The role of spin quantum number and frustration strength on sublattice magnetization, Néel temperature, internal energy, and free energy are carefully analyzed. The curve of zero-temperature sublattice magnetization / S versus frustration strength J2/J1 values are almost flat at the larger spin quantum number S=10. With the increase of normalized temperature T/TN, the larger the spin quantum number S, the faster the / S drops, and the smaller influence of J2/J1 on the / S versus T/TN curve. Under the RPA approach, the Néel temperature TN /Sp and the internal energy E/Sp at the Néel point are independent of spin quantum number S. The numerical results show that the internal energy E/Sp at the Néel point seems independent of the frustration strength J2/J1. This indicates that thermodynamic quantities have universal characteristics for large spin quantum number.

  1. Anisotropic Phase diagram of the Frustrated spin chain β-TeVO4

    NASA Astrophysics Data System (ADS)

    Weickert, F.; Jaime, M.; Harrison, N.; Scott, B. L.; Leitmae, A.; Heinmaa, L.; Stern, R.; Janson, O.; Berger, H.; Rosner, H.; Tsirlin, A. A.

    We will present experimental as well as theoretical data on β-TeVO4 a candidate for the J1-J2 chain model with ferromagnetic J1 ~-18 K and antiferrromagnetic J2 ~48 K coupling constants. The T - H magnetic phase diagram is revealed by measurements of the magnetization, specific heat, magnetostriction, and thermal expansion on oriented single crystals at temperatures between 0.5 K and 50 K and in magnetic fields up to 50 T. The high field data were taken in a capacitor bank-driven pulsed magnet at NHMFL - LANL and complemented with measurements in a superconducting magnet. Our comprehensive study allows for the first time a detailed mapping of the phase diagram in both directions, H ll ab and H ll c. We find clear evidence for 5 different phases including full polarization of the magnetic moments above 23 T that is only weakly dependent on the crystal orientation. Surprisingly, the phase boundary at the saturation field splits into two distinct lines below 5 K. The magnetic phases occurring at fields below 10 T show significant magnetic anisotropy between H ll ab and H ll c. The nature of the different phases and regions in β-TeVO4 is still far from being understood, but our results will stimulate further research on this interesting model compound.

  2. Phase stability frustration on ultra-nanosized anatase TiO2.

    PubMed

    Patra, Snehangshu; Davoisne, Carine; Bouyanfif, Houssny; Foix, Dominique; Sauvage, Frédéric

    2015-06-04

    This work sheds light on the exceptional robustness of anatase TiO2 when it is downsized to an extreme value of 4 nm. Since at this size the surface contribution to the volume becomes predominant, it turns out that the material becomes significantly resistant against particles coarsening with temperature, entailing a significant delay in the anatase to rutile phase transition, prolonging up to 1000 °C in air. A noticeable alteration of the phase stability diagram with lithium insertion is also experienced. Lithium insertion in such nanocrystalline anatase TiO2 converts into a complete solid solution until almost Li1TiO2, a composition at which the tetragonal to orthorhombic transition takes place without the formation of the emblematic and unwished rock salt Li1TiO2 phase. Consequently, excellent reversibility in the electrochemical process is experienced in the whole portion of lithium content.

  3. Phase stability frustration on ultra-nanosized anatase TiO2

    PubMed Central

    Patra, Snehangshu; Davoisne, Carine; Bouyanfif, Houssny; Foix, Dominique; Sauvage, Frédéric

    2015-01-01

    This work sheds light on the exceptional robustness of anatase TiO2 when it is downsized to an extreme value of 4 nm. Since at this size the surface contribution to the volume becomes predominant, it turns out that the material becomes significantly resistant against particles coarsening with temperature, entailing a significant delay in the anatase to rutile phase transition, prolonging up to 1000 °C in air. A noticeable alteration of the phase stability diagram with lithium insertion is also experienced. Lithium insertion in such nanocrystalline anatase TiO2 converts into a complete solid solution until almost Li1TiO2, a composition at which the tetragonal to orthorhombic transition takes place without the formation of the emblematic and unwished rock salt Li1TiO2 phase. Consequently, excellent reversibility in the electrochemical process is experienced in the whole portion of lithium content. PMID:26042388

  4. Effect of disorder in the frustrated Ising FCC antiferromagnet: phase diagram and stretched exponential relaxation

    NASA Astrophysics Data System (ADS)

    Ngo, V. Thanh; Hoang, D. Tien; Diep, H. T.; Campbell, I. A.

    2014-04-01

    In this paper, we study the phase transition in a face-centered-cubic antiferromagnet with Ising spins as a function of the concentration p of ferromagnetic bonds randomly introduced into the system. Such a model describes the spin-glass phase at strong bond disorder. Using the standard Monte Carlo simulation and the powerful Wang-Landau flat-histogram method, we carry out in this work intensive simulations over the whole range of p. We show that the first-order transition disappears with a tiny amount of ferromagnetic bonds, namely p 0.01, in agreement with theories and simulations on other 3D models. The antiferromagnetic long-range order is also destroyed with a very small p (≃5%). With increasing p, the system changes into a spin glass and then to a ferromagnetic phase when p > 0.65. The phase diagram in the space (Tc, p) shows an asymmetry, unlike the case of the ±J Ising spin glass on the simple cubic lattice. We calculate the relaxation time around the spin-glass transition temperature and we show that the spin autocorrelation follows a stretched exponential relaxation law where the factor b is equal to ≃1/3 at the transition as suggested by the percolation-based theory. This value is in agreement with experiments performed on various spin glasses and with Monte Carlo simulations on different SG models.

  5. Wetting and phase separation in soft adhesion

    PubMed Central

    Jensen, Katharine E.; Sarfati, Raphael; Style, Robert W.; Boltyanskiy, Rostislav; Chakrabarti, Aditi; Chaudhury, Manoj K.; Dufresne, Eric R.

    2015-01-01

    In the classic theory of solid adhesion, surface energy drives deformation to increase contact area whereas bulk elasticity opposes it. Recently, solid surface stress has been shown also to play an important role in opposing deformation of soft materials. This suggests that the contact line in soft adhesion should mimic that of a liquid droplet, with a contact angle determined by surface tensions. Consistent with this hypothesis, we observe a contact angle of a soft silicone substrate on rigid silica spheres that depends on the surface functionalization but not the sphere size. However, to satisfy this wetting condition without a divergent elastic stress, the gel phase separates from its solvent near the contact line. This creates a four-phase contact zone with two additional contact lines hidden below the surface of the substrate. Whereas the geometries of these contact lines are independent of the size of the sphere, the volume of the phase-separated region is not, but rather depends on the indentation volume. These results indicate that theories of adhesion of soft gels need to account for both the compressibility of the gel network and a nonzero surface stress between the gel and its solvent. PMID:26553989

  6. Active Nematics Are Intrinsically Phase Separated

    NASA Astrophysics Data System (ADS)

    Mishra, Shradha; Ramaswamy, Sriram

    2006-09-01

    Two-dimensional nonequilibrium nematic steady states, as found in agitated granular-rod monolayers or films of orientable amoeboid cells, were predicted [Europhys. Lett. 62, 196 (2003)EULEEJ0295-507510.1209/epl/i2003-00346-7] to have giant number fluctuations, with the standard deviation proportional to the mean. We show numerically that the steady state of such systems is macroscopically phase separated, yet dominated by fluctuations, as in the Das-Barma model [Phys. Rev. Lett. 85, 1602 (2000)PRLTAO0031-900710.1103/PhysRevLett.85.1602]. We suggest experimental tests of our findings in granular and living-cell systems.

  7. Frustrated quantum phase diffusion and increased coherence of solitons due to nonlocality

    SciTech Connect

    Batz, Sascha; Peschel, Ulf

    2011-03-15

    We investigate the quantum properties of solitons with nonlocal self-interaction. We find significant changes when compared to the local interaction. Quantum phase diffusion of nonlocal solitons is always reduced with respect to the local interaction and vanishes in the strongly nonlocal limit. Thus, coherence is increased in the nonlocal case. Furthermore, we compare the intrinsic quantum wave packet spreading to the recently discussed classical Gordon-Haus effect for nonlocal solitons [V. Folli and C. Conti, Phys. Rev. Lett. 104, 193901 (2010)].

  8. Critical space-time networks and geometric phase transitions from frustrated edge antiferromagnetism.

    PubMed

    Trugenberger, Carlo A

    2015-12-01

    Recently I proposed a simple dynamical network model for discrete space-time that self-organizes as a graph with Hausdorff dimension d(H)=4. The model has a geometric quantum phase transition with disorder parameter (d(H)-d(s)), where d(s) is the spectral dimension of the dynamical graph. Self-organization in this network model is based on a competition between a ferromagnetic Ising model for vertices and an antiferromagnetic Ising model for edges. In this paper I solve a toy version of this model defined on a bipartite graph in the mean-field approximation. I show that the geometric phase transition corresponds exactly to the antiferromagnetic transition for edges, the dimensional disorder parameter of the former being mapped to the staggered magnetization order parameter of the latter. The model has a critical point with long-range correlations between edges, where a continuum random geometry can be defined, exactly as in Kazakov's famed 2D random lattice Ising model but now in any number of dimensions.

  9. Critical space-time networks and geometric phase transitions from frustrated edge antiferromagnetism

    NASA Astrophysics Data System (ADS)

    Trugenberger, Carlo A.

    2015-12-01

    Recently I proposed a simple dynamical network model for discrete space-time that self-organizes as a graph with Hausdorff dimension dH=4 . The model has a geometric quantum phase transition with disorder parameter (dH-ds) , where ds is the spectral dimension of the dynamical graph. Self-organization in this network model is based on a competition between a ferromagnetic Ising model for vertices and an antiferromagnetic Ising model for edges. In this paper I solve a toy version of this model defined on a bipartite graph in the mean-field approximation. I show that the geometric phase transition corresponds exactly to the antiferromagnetic transition for edges, the dimensional disorder parameter of the former being mapped to the staggered magnetization order parameter of the latter. The model has a critical point with long-range correlations between edges, where a continuum random geometry can be defined, exactly as in Kazakov's famed 2D random lattice Ising model but now in any number of dimensions.

  10. Phase Separation in the Heisenberg Spin System Gd2Ti2O7

    SciTech Connect

    Ehlers, Georg

    2010-01-01

    Gd{sub 2}Ti{sub 2}O{sub 7} is a geometrically frustrated antiferromagnetic system with two magnetic phase transitions at 1.1 K and 0.7 K. The determination of the magnetic structure in the ordered phases by a powder measurement is greatly complicated by the ambiguity between 1-k and 4-k structures resulting in identical structure factors. Here we will present data and new analyses showing that, as the system cools from the correlated, paramagnetic regime just above 1 K, (i) the magnetic system freezes into a partially ordered state, and (ii) the 4-k structure is maintained throughout down to a base temperature <50 mK. This clears up the ambiguity in the magnetic structure and confirms the phase separation of the Gd-sites into two in equivalent sites with a 3:1 ratio.

  11. PREFACE: Geometrically frustrated magnetism Geometrically frustrated magnetism

    NASA Astrophysics Data System (ADS)

    Gardner, Jason S.

    2011-04-01

    Frustrated magnetism is an exciting and diverse field in condensed matter physics that has grown tremendously over the past 20 years. This special issue aims to capture some of that excitement in the field of geometrically frustrated magnets and is inspired by the 2010 Highly Frustrated Magnetism (HFM 2010) meeting in Baltimore, MD, USA. Geometric frustration is a broad phenomenon that results from an intrinsic incompatibility between some fundamental interactions and the underlying lattice geometry based on triangles and tetrahedra. Most studies have centred around the kagomé and pyrochlore based magnets but recent work has looked at other structures including the delafossite, langasites, hyper-kagomé, garnets and Laves phase materials to name a few. Personally, I hope this issue serves as a great reference to scientist both new and old to this field, and that we all continue to have fun in this very frustrated playground. Finally, I want to thank the HFM 2010 organizers and all the sponsors whose contributions were an essential part of the success of the meeting in Baltimore. Geometrically frustrated magnetism contents Spangolite: an s = 1/2 maple leaf lattice antiferromagnet? T Fennell, J O Piatek, R A Stephenson, G J Nilsen and H M Rønnow Two-dimensional magnetism and spin-size effect in the S = 1 triangular antiferromagnet NiGa2S4 Yusuke Nambu and Satoru Nakatsuji Short range ordering in the modified honeycomb lattice compound SrHo2O4 S Ghosh, H D Zhou, L Balicas, S Hill, J S Gardner, Y Qi and C R Wiebe Heavy fermion compounds on the geometrically frustrated Shastry-Sutherland lattice M S Kim and M C Aronson A neutron polarization analysis study of moment correlations in (Dy0.4Y0.6)T2 (T = Mn, Al) J R Stewart, J M Hillier, P Manuel and R Cywinski Elemental analysis and magnetism of hydronium jarosites—model kagome antiferromagnets and topological spin glasses A S Wills and W G Bisson The Herbertsmithite Hamiltonian: μSR measurements on single crystals

  12. Porous polymers by controlling phase separation during vapor deposition polymerization.

    PubMed

    Tao, Ran; Anthamatten, Mitchell

    2013-11-01

    A template-free method is described to fabricate continuous-phase, porous polymer films by simultaneous phase separation during vapor deposition polymerization. The technique involves concurrent polymerization, crosslinking, and phase separation of condensed species and reaction products. Deposited films form open-cell, macroporous structures consisting of crosslinked and glassy poly(glycidyl methacrylate). By limiting phase separation during vapor phase deposition, spatially dependent morphologies, such as layered morphologies, can be grown. Results show that combining vapor deposition polymerization with phase separation establishes morphological control, which may be applied to applications including cellular scaffolds, thin cushions and vibration dampers, and membranes for separations.

  13. Level crossing, spin structure factor and quantum phases of the frustrated spin-1/2 chain with first and second neighbor exchange.

    PubMed

    Kumar, Manoranjan; Parvej, Aslam; Soos, Zoltán G

    2015-08-12

    The spin-1/2 chain with isotropic Heisenberg exchange J1, J2  >  0 between first and second neighbors is frustrated for either sign of J1. Its quantum phase diagram has critical points at fixed J1/J2 between gapless phases with nondegenerate ground state (GS) and quasi-long-range order (QLRO) and gapped phases with doubly degenerate GS and spin correlation functions of finite range. In finite chains, exact diagonalization (ED) estimates critical points as level crossing of excited states. GS spin correlations enter in the spin structure factor S(q) that diverges at wave vector qm in QLRO(q(m)) phases with periodicity 2π/q(m) but remains finite in gapped phases. S(q(m)) is evaluated using ED and density matrix renormalization group (DMRG) calculations. Level crossing and the magnitude of S(q(m)) are independent and complementary probes of quantum phases, based respectively on excited and ground states. Both indicate a gapless QLRO(π/2) phase between  -1.2  <  J1/|J2|  <  0.45. Numerical results and field theory agree well for quantum critical points at small frustration J2 but disagree in the sector of weak exchange J1 between Heisenberg antiferromagnetic chains on sublattices of odd and even-numbered sites.

  14. Griffiths phase and temporal effects in phase separated manganites

    NASA Astrophysics Data System (ADS)

    Krivoruchko, V. N.; Marchenko, M. A.

    2016-08-01

    Phenomenological description of relaxation phenomena in magnetic and transport properties of perovskite manganites has been presented. The approach is based on generalization of some hypotheses appropriate to the Preisach picture of magnetization process for half-metallic ferromagnets and on an assumption that in doped manganites the phase separated state exists near the magnetic ordering temperature. For systems with the percolation type of a ferromagnet-paramagnet transition, distinctive features in relaxation of magnetization and resistivity have been found. The relaxation is shown to be most pronounced near the transition temperature, and to be an approximately logarithmic function of time. The theoretical results replicate a broad spectrum of behavior observed experimentally on time dependence of magnetization and resistivity of CMR systems and allow a direct comparison with available experimental data. We propose an additional experimental test to distinguish between the percolation scenario of magnetic and transport transitions in doped manganites, and the ferromagnetic polaron picture. In particular, an anomalously slow relaxation to zero of the order parameter can be considered as a key feature of the Griffiths-like phase transition in doped manganites. It is also shown that a system with the Griffiths-like state will exhibit nonequilibrium aging and rejuvenation phenomena, which in many aspects resemble that of a spin glass. We hope that experimental observation of a set of time decay properties will provide a settlement of apparently conflicting results obtained for different characteristics of phase-separated manganites.

  15. Magnetic phase transitions in two-dimensional frustrated Cu3R(SeO3)2O2Cl. Spectroscopic study

    NASA Astrophysics Data System (ADS)

    Klimin, S. A.; Budkin, I. V.

    2016-12-01

    Using optical study of electronic spectra of rare-earth (RE) ions, magnetic phase transitions in the low-dimensional frustrated RE magnets Cu3R(SeO3)2O2Cl (R = Sm, Yb, Er, Nd, Pr, Eu) were investigated. Phase transitions were registered either by splittings of crystal-field (CF) doublets or by repulsion of CF levels of f-ions in a staggered magnetic field. Different scenarios of magnetic order in isostructural compounds of the francisite family are discussed.

  16. The Kinetics of Phase Separation in Asymmetric Membranes

    PubMed Central

    Wallace, Elizabeth J.; Hooper, Nigel M.; Olmsted, Peter D.

    2005-01-01

    Phase separation in a model asymmetric membrane is studied using Monte Carlo techniques. The membrane comprises two species of particles, which mimic different lipids in lipid bilayers and separately possess either zero or non-zero spontaneous curvatures. We study the influence of phase separation on membrane shape and the influence of the coupling of composition and height dynamics on phase separation and domain growth, via both the degree of shape asymmetry and relative kinetic coefficients for height relaxation. PMID:15778446

  17. Classical Antiferromagnetism in Kinetically Frustrated Electronic Models

    NASA Astrophysics Data System (ADS)

    Sposetti, C. N.; Bravo, B.; Trumper, A. E.; Gazza, C. J.; Manuel, L. O.

    2014-05-01

    We study, by means of the density matrix renormalization group, the infinite U Hubbard model—with one hole doped away from half filling—in triangular and square lattices with frustrated hoppings, which invalidate Nagaoka's theorem. We find that these kinetically frustrated models have antiferromagnetic ground states with classical local magnetization in the thermodynamic limit. We identify the mechanism of this kinetic antiferromagnetism with the release of the kinetic energy frustration, as the hole moves in the established antiferromagnetic background. This release can occur in two different ways: by a nontrivial spin Berry phase acquired by the hole, or by the effective vanishing of the hopping amplitude along the frustrating loops.

  18. Strain phase separation: Formation of ferroelastic domain structures

    NASA Astrophysics Data System (ADS)

    Xue, Fei; Li, Yongjun; Gu, Yijia; Zhang, Jinxing; Chen, Long-Qing

    2016-12-01

    Phase decomposition is a well-known process leading to the formation of two-phase mixtures. Here we show that a strain imposed on a ferroelastic crystal promotes the formation of mixed phases and domains, i.e., strain phase separation with local strains determined by a common tangent construction on the free energy versus strain curves. It is demonstrated that a domain structure can be understood using the concepts of domain/phase rule, lever rule, and coherent and incoherent strain phase separation, in a complete analogy to phase decomposition. The proposed strain phase separation model is validated using phase-field simulations and experimental observations of PbTi O3 and BiFe O3 thin films as examples. The proposed model provides a simple tool to guide and design domain structures of ferroelastic systems.

  19. Optical Bragg, atomic Bragg and cavity QED detections of quantum phases and excitation spectra of ultracold atoms in bipartite and frustrated optical lattices

    SciTech Connect

    Ye, Jinwu; Zhang, K.Y.; Li, Yan; Chen, Yan; Zhang, W.P.

    2013-01-15

    Ultracold atoms loaded on optical lattices can provide unprecedented experimental systems for the quantum simulations and manipulations of many quantum phases and quantum phase transitions between these phases. However, so far, how to detect these quantum phases and phase transitions effectively remains an outstanding challenge. In this paper, we will develop a systematic and unified theory of using the optical Bragg scattering, atomic Bragg scattering or cavity QED to detect the ground state and the excitation spectrum of many quantum phases of interacting bosons loaded in bipartite and frustrated optical lattices. The physically measurable quantities of the three experiments are the light scattering cross sections, the atom scattered clouds and the cavity leaking photons respectively. We show that the two photon Raman transition processes in the three detection methods not only couple to the density order parameter, but also the valence bond order parameter due to the hopping of the bosons on the lattice. This valence bond order coupling is very sensitive to any superfluid order or any valence bond (VB) order in the quantum phases to be probed. These quantum phases include not only the well-known superfluid and Mott insulating phases, but also other important phases such as various kinds of charge density waves (CDW), valence bond solids (VBS), and CDW-VBS phases with both CDW and VBS orders unique to frustrated lattices, and also various kinds of supersolids. We analyze respectively the experimental conditions of the three detection methods to probe these various quantum phases and their corresponding excitation spectra. We also address the effects of a finite temperature and a harmonic trap. We contrast the three scattering methods with recent in situ measurements inside a harmonic trap and argue that the two kinds of measurements are complementary to each other. The combination of both kinds of detection methods could be used to match the combination of

  20. Superfluid helium 2 liquid-vapor phase separation: Technology assessment

    NASA Technical Reports Server (NTRS)

    Lee, J. M.

    1984-01-01

    A literature survey of helium 2 liquid vapor phase separation is presented. Currently, two types of He 2 phase separators are being investigated: porous, sintered metal plugs and the active phase separator. The permeability K(P) shows consistency in porous plug geometric characterization. Both the heat and mass fluxes increase with K(P). Downstream pressure regulation to adjust for varying heat loads and both temperatures is possible. For large dynamic heat loads, the active phase separator shows a maximum heat rejection rate of up to 2 W and bath temperature stability of 0.1 mK. Porous plug phase separation performance should be investigated for application to SIRTF and, in particular, that plugs of from 10 to the minus ninth square centimeters to 10 to the minus eighth square centimeters in conjunction with downstream pressure regulation be studied.

  1. Sequence-Specific Polyampholyte Phase Separation in Membraneless Organelles

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsuan; Forman-Kay, Julie D.; Chan, Hue Sun

    2016-10-01

    Liquid-liquid phase separation of charge- and/or aromatic-enriched intrinsically disordered proteins (IDPs) is critical in the biological function of membraneless organelles. Much of the physics of this recent discovery remains to be elucidated. Here, we present a theory in the random phase approximation to account for electrostatic effects in polyampholyte phase separations, yielding predictions consistent with recent experiments on the IDP Ddx4. The theory is applicable to any charge pattern and thus provides a general analytical framework for studying sequence dependence of IDP phase separation.

  2. Phase transitions in a frustrated biquadratic Heisenberg model with coupled orbital degrees of freedom for iron-based superconductors

    NASA Astrophysics Data System (ADS)

    Zhuo, W. Z.; Qin, M. H.; Dong, S.; Li, X. G.; Liu, J.-M.

    2016-03-01

    In this paper, we study a biquadratic Heisenberg model with coupled orbital degrees of freedom by using a Monte Carlo simulation to investigate the phase transitions in iron-based superconductors. The antiferroquadrupolar state, which may be related to the magnetism of FeSe [R. Yu and Q. Si, Phys. Rev. Lett. 115, 116401 (2015), 10.1103/PhysRevLett.115.116401], is stabilized by the anisotropic biquadratic interaction induced by a ferro-orbital-ordered state. It is revealed that the orbital and nematic transitions occur at the same temperature for all the cases, supporting the mechanism of the orbital-driven nematicity as revealed in most recent experiments [S. H. Baek, D. V. Efremov, J. M. Ok, J. S. Kim, J. van den Brink, and B. Büchner, Nat. Mater. 14, 210 (2015), 10.1038/nmat4138]. In addition, it is suggested that the orbital interaction may lead to the separation of the structural and magnetic phase transitions, as observed in many families of iron pnictides.

  3. SEC/reversed-phase separation of E. coli proteins.

    PubMed

    Apffell, Alex

    2010-05-01

    Although many chromatographic modes can be coupled for the multidimensional separation of a complex mixture, a very favorable combination is that of size-exclusion chromatography (SEC) and reversed-phase chromatography. The separation mechanisms are largely orthogonal and the mobile phases are compatible. The use of a retentive second dimension allows trapping of specific fractions from the SEC separation and transferring them to the reversed-phase separation. One of the advantages of multidimensional chromatography is that it is scalable in terms of automation. In a completely manual system, fractions eluting from a first dimension can be manually collected and injected into a second separation dimension. In an automated system, fraction transfer can be accomplished through automated valving. The following protocol illustrates this approach, with both a manual method and an external column switching method integrated into an automated high-performance liquid chromatography (HPLC) method. As an illustration, soluble proteins from Escherichia coli are separated.

  4. Frustration in biomolecules.

    PubMed

    Ferreiro, Diego U; Komives, Elizabeth A; Wolynes, Peter G

    2014-11-01

    Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and especially how biomolecular structure connects to function by means of localized frustration. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. In this review, we also emphasize that frustration, far from being always a bad thing, is an essential feature

  5. Continuum Theory of Phase Separation Kinetics for Active Brownian Particles

    NASA Astrophysics Data System (ADS)

    Stenhammar, Joakim; Tiribocchi, Adriano; Allen, Rosalind J.; Marenduzzo, Davide; Cates, Michael E.

    2013-10-01

    Active Brownian particles (ABPs), when subject to purely repulsive interactions, are known to undergo activity-induced phase separation broadly resembling an equilibrium (attraction-induced) gas-liquid coexistence. Here we present an accurate continuum theory for the dynamics of phase-separating ABPs, derived by direct coarse graining, capturing leading-order density gradient terms alongside an effective bulk free energy. Such gradient terms do not obey detailed balance; yet we find coarsening dynamics closely resembling that of equilibrium phase separation. Our continuum theory is numerically compared to large-scale direct simulations of ABPs and accurately accounts for domain growth kinetics, domain topologies, and coexistence densities.

  6. Phase Separators And Fountain-Effect Pumps For He 11

    NASA Technical Reports Server (NTRS)

    Whitehouse, Paul L.

    1989-01-01

    Fused-glass microchannel arrays for use as HE 11 phase separators and fountain-effect pumps. Microchannel devices for use in low-gravity storage and cooling systems containing superfluid helium. Phase separators and pumps take advantage of thermomechanical effect peculiar to He 11 in restricted spaces. By creating thermal gradient in porous plug, direction of flow reversed, turning phase separator into pump. However, addition of heat disadvantage. Thermal gradient created by using Peltier effect to transfer heat across array, removing heat from He 11 supply and overcoming undesirable addition of heat.

  7. Phase separation and the formation of cellular bodies

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Broedersz, Chase P.; Meir, Yigal; Wingreen, Ned S.

    Cellular bodies in eukaryotic cells spontaneously assemble to form cellular compartments. Among other functions, these bodies carry out essential biochemical reactions. Cellular bodies form micron-sized structures, which, unlike canonical cell organelles, are not surrounded by membranes. A recent in vitro experiment has shown that phase separation of polymers in solution can explain the formation of cellular bodies. We constructed a lattice-polymer model to capture the essential mechanism leading to this phase separation. We used both analytical and numerical tools to predict the phase diagram of a system of two interacting polymers, including the concentration of each polymer type in the condensed and dilute phase.

  8. Phase separation in the isolation and purification of membrane proteins.

    PubMed

    Arnold, Thomas; Linke, Dirk

    2007-10-01

    Phase separation is a simple, efficient, and cheap method to purify and concentrate detergent-solubilized membrane proteins. In spite of this, phase separation is not widely used or even known among membrane protein scientists, and ready-to-use protocols are available for only relatively few detergent/membrane protein combinations. Here, we summarize the physical and chemical parameters that influence the phase separation behavior of detergents commonly used for membrane protein studies. Examples for the successful purification of membrane proteins using this method with different classes of detergents are provided. As the choice of the detergent is critical in many downstream applications (e.g., membrane protein crystallization or functional assays), we discuss how new phase separation protocols can be developed for a given detergent buffer system.

  9. Separation of Chloroplast Pigments Using Reverse Phase Chromatography.

    ERIC Educational Resources Information Center

    Reese, R. Neil

    1997-01-01

    Presents a protocol that uses reverse phase chromatography for the separation of chloroplast pigments. Provides a simple and relatively safe procedure for use in teaching laboratories. Discusses pigment extraction, chromatography, results, and advantages of the process. (JRH)

  10. Phase-Locked Semiconductor Lasers With Separate Contacts

    NASA Technical Reports Server (NTRS)

    Katz, Joseph; Yariv, Amnon; Margalit, Shlomo

    1988-01-01

    Individual current feeds enable better uniformity and flexible control. Separate contacts for lasers in array enable control of output radiation pattern and compensation of manufacturing nonuniformities among lasers. Concept of separate current control described for two-laser array in "Semiconductor Laser Phased Array" (NPO-15963).

  11. Probe diffusion in phase-separated bicontinuous biopolymer gels.

    PubMed

    Wassén, Sophia; Bordes, Romain; Gebäck, Tobias; Bernin, Diana; Schuster, Erich; Lorén, Niklas; Hermansson, Anne-Marie

    2014-11-07

    Probe diffusion was determined in phase separated bicontinuous gels prepared by acid-induced gelation of the whey protein isolate-gellan gum system. The topological characterization of the phase-separated gel systems is achieved by confocal microscopy and the diffusion measurements are performed using pulsed field gradient (PFG) NMR and fluorescence recovery after photo-bleaching (FRAP). These two techniques gave complementary information about the mass transport at different time- and length scales, PFG NMR provided global diffusion rates in the gel systems, while FRAP enabled the measurements of diffusion in different phases of the phase-separated gels. The results revealed that the phase-separated gel with the largest characteristic wavelength had the fastest diffusion coefficient, while the gel with smaller microstructures had a slower probe diffusion rate. By using the diffusion data obtained by FRAP and the structural data from confocal microscopy, modelling through the lattice-Boltzmann framework was carried out to simulate the global diffusion and verify the validity of the experimental measurements. With this approach it was found that discrepancies between the two experimental techniques can be rationalized in terms of probe distribution between the different phases of the system. The combination of different techniques allowed the determination of diffusion in a phase-separated biopolymer gel and gave a clearer picture of this complex system. We also illustrate the difficulties that can arise if precautions are not taken to understand the system-probe interactions.

  12. Frustration in Biomolecules

    PubMed Central

    Ferreiro, Diego U.; Komives, Elizabeth A.; Wolynes, Peter G.

    2014-01-01

    Biomolecules are the prime information processing elements of living matter. Most of these inanimate systems are polymers that compute their own structures and dynamics using as input seemingly random character strings of their sequence, following which they coalesce and perform integrated cellular functions. In large computational systems with a finite interaction-codes, the appearance of conflicting goals is inevitable. Simple conflicting forces can lead to quite complex structures and behaviors, leading to the concept of frustration in condensed matter. We present here some basic ideas about frustration in biomolecules and how the frustration concept leads to a better appreciation of many aspects of the architecture of biomolecules, and how biomolecular structure connects to function. These ideas are simultaneously both seductively simple and perilously subtle to grasp completely. The energy landscape theory of protein folding provides a framework for quantifying frustration in large systems and has been implemented at many levels of description. We first review the notion of frustration from the areas of abstract logic and its uses in simple condensed matter systems. We discuss then how the frustration concept applies specifically to heteropolymers, testing folding landscape theory in computer simulations of protein models and in experimentally accessible systems. Studying the aspects of frustration averaged over many proteins provides ways to infer energy functions useful for reliable structure prediction. We discuss how frustration affects folding mechanisms. We review here how a large part of the biological functions of proteins are related to subtle local physical frustration effects and how frustration influences the appearance of metastable states, the nature of binding processes, catalysis and allosteric transitions. We hope to illustrate how Frustration is a fundamental concept in relating function to structural biology. PMID:25225856

  13. Separate Magnitude and Phase Regularization via Compressed Sensing

    PubMed Central

    Noll, Douglas C.; Nielsen, Jon-Fredrik; Fessler, Jeffrey A.

    2012-01-01

    Compressed sensing (CS) has been used for accelerating magnetic resonance imaging (MRI) acquisitions, but its use in applications with rapid spatial phase variations is challenging, e.g., proton resonance frequency shift (PRF-shift) thermometry and velocity mapping. Previously, an iterative MRI reconstruction with separate magnitude and phase regularization was proposed for applications where magnitude and phase maps are both of interest, but it requires fully sampled data and unwrapped phase maps. In this paper, CS is combined into this framework to reconstruct magnitude and phase images accurately from undersampled data. Moreover, new phase regularization terms are proposed to accommodate phase wrapping and to reconstruct images with encoded phase variations, e.g., PRF-shift thermometry and velocity mapping. The proposed method is demonstrated with simulated thermometry data and in-vivo velocity mapping data and compared to conventional phase corrected CS. PMID:22552571

  14. Texas A&M vortex type phase separator

    NASA Astrophysics Data System (ADS)

    Best, Frederick

    2000-01-01

    Phase separation is required for regenerative biological and chemical process systems as well as thermal transport and rejection systems. Liquid and gas management requirements for future spacecraft will demand small, passive systems able to operate over wide ranges of inlet qualities. Conservation and recycling of air and water is a necessary part of the construction and operation of the International Space Station as well as future long duration space missions. Space systems are sensitive to volume, mass, and power. Therefore, it is necessary to develop a method to recycle wastewater with minimal power consumption. Regenerative life support systems currently being investigated require phase separation to separate the liquid from the gas produced. The microgravity phase separator designed and fabricated at Texas A&M University relies on centripetal driven buoyancy forces to form a gas-liquid vortex within a fixed, right-circular cylinder. Two-phase flow is injected tangentially along the inner wall of this cylinder producing a radial acceleration gradient. The gradient produced from the intrinsic momentum of the injected mixture results in a rotating flow that drives the buoyancy process by the production of a hydrostatic pressure gradient. Texas A&M has flown several KC-135 flights with separator. These flights have included scaling studies, stability and transient investigations, and tests for inventory instrumentation. Among the hardware tested have been passive devices for separating mixed vapor/liquid streams into single-phase streams of vapor only and liquid only. .

  15. Chromatographic Separations Using Solid-Phase Extraction Cartridges: Separation of Wine Phenolics

    NASA Astrophysics Data System (ADS)

    Brenneman, Charles A.; Ebeler, Susan E.

    1999-12-01

    We describe a simple laboratory experiment that demonstrates the principles of chromatographic separation using solid-phase extraction columns and red wine. By adjusting pH and mobile phase composition, the wine is separated into three fractions of differing polarity. The content of each fraction can be monitored by UV-vis spectroscopy. When the experiment is combined with experiments involving HPLC or GC separations, students gain a greater appreciation for and understanding of the highly automated instrumental systems currently available. In addition, they learn about the chemistry of polyphenolic compounds, which are present in many foods and beverages and which are receiving much attention for their potentially beneficial health effects.

  16. Laser-induced phase separation of silicon carbide.

    PubMed

    Choi, Insung; Jeong, Hu Young; Shin, Hyeyoung; Kang, Gyeongwon; Byun, Myunghwan; Kim, Hyungjun; Chitu, Adrian M; Im, James S; Ruoff, Rodney S; Choi, Sung-Yool; Lee, Keon Jae

    2016-11-30

    Understanding the phase separation mechanism of solid-state binary compounds induced by laser-material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (∼2.5 nm) and polycrystalline silicon (∼5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system.

  17. Laser-induced phase separation of silicon carbide

    PubMed Central

    Choi, Insung; Jeong, Hu Young; Shin, Hyeyoung; Kang, Gyeongwon; Byun, Myunghwan; Kim, Hyungjun; Chitu, Adrian M.; Im, James S.; Ruoff, Rodney S.; Choi, Sung-Yool; Lee, Keon Jae

    2016-01-01

    Understanding the phase separation mechanism of solid-state binary compounds induced by laser–material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (∼2.5 nm) and polycrystalline silicon (∼5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system. PMID:27901015

  18. Laser-induced phase separation of silicon carbide

    NASA Astrophysics Data System (ADS)

    Choi, Insung; Jeong, Hu Young; Shin, Hyeyoung; Kang, Gyeongwon; Byun, Myunghwan; Kim, Hyungjun; Chitu, Adrian M.; Im, James S.; Ruoff, Rodney S.; Choi, Sung-Yool; Lee, Keon Jae

    2016-11-01

    Understanding the phase separation mechanism of solid-state binary compounds induced by laser-material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (~2.5 nm) and polycrystalline silicon (~5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system.

  19. Phase separation of lanthanum hydride under high pressure

    NASA Astrophysics Data System (ADS)

    Machida, A.; Watanuki, T.; Kawana, D.; Aoki, K.

    2011-02-01

    Structural change of lanthanum dihydride LaH2.3, which has a face-centered-cubic (fcc) metal lattice with tetrahedral interstitial sites fully occupied with hydrogen atoms and partially occupied octahedral sites, has been investigated at high pressures up to 20 GPa at ambient temperature by synchrotron radiation x-ray diffraction. Additional Bragg reflections appear just on higher angle sides of the original ones at ~11 GPa and their peak intensities increase gradually on further compression. The coexistence state of two fcc metal lattices thus observed above 11 GPa is interpreted in terms of phase separation or disproportionation reaction from the dihydride toward a solid solution and trihydride states, in both of which the octahedral interstitial sites are partially occupied with hydrogen atoms. A gradual distortion from the cubic to a tetragonal lattice is observed prior to the phase separation. The coexistence phase goes back to the dihydride fcc phase via the lattice distorted phase with decreasing pressure.

  20. Gas Phase Chiral Separations By Ion Mobility Spectrometry

    PubMed Central

    Dwivedi, Prabha; Wu, Ching; Hill, Herbert H.

    2013-01-01

    This manuscript introduces the concept of Chiral Ion Mobility Spectrometry (CIMS) and presents examples demonstrating the gas phase separation of enantiomers of a wide range of racemates including pharmaceuticals, amino acids and carbohydrates. CIMS is similar to traditional ion mobility spectrometry (IMS), where gas phase ions, when subjected to a potential gradient are separated at atmospheric pressure due to differences in their shapes and sizes. In addition to size and shape, CIMS separates ions based on their stereospecific interaction with a chiral gas. In order to achieve chiral discrimination by CIMS, an asymmetric environment was provided by doping the drift gas with a volatile chiral reagent. In this study S-(+)-2-butanol was used as a chiral modifier to demonstrate enantiomeric separations of atenolol, serine, methionine, threonine, methyl-α-glucopyranoside, glucose, penicillamine, valinol, phenylalanine, and tryptophan from their respective racemic mixtures. PMID:17165808

  1. Phase separation during radiation crosslinking of unsaturated polyester resin

    NASA Astrophysics Data System (ADS)

    Pucić, Irina; Ranogajec, Franjo

    2003-06-01

    Phase separation during radiation-initiated crosslinking of unsaturated polyester resin was studied. Residual reactivity of liquid phases and gels of partially cured samples was determined by DSC. Uncured resin and liquid phases showed double reaction exotherm, gels had a single maximum that corresponded to higher-temperature maximum of liquid parts. The lower-temperature process was attributed to styrene-polyester copolymerization. At higher temperatures, polyester unsaturations that remained unreacted due to microgel formation homopolymerized. FTIR revealed different composition of phases. In thicker samples, reaction heat influenced microgel formation causing delayed appearance of gel and faster increase in conversion.

  2. Supercritical fluid phase separations induced by chemical reactions

    SciTech Connect

    Ree, F.H.; Viecelli, J.A.; van Thiel, M.

    1997-11-01

    Our statistical mechanical studies predict that a chemically reactive system containing species composed of C, H, N, O atoms can exhibit a phase separation into a N{sub 2}-rich and a N{sub 2}-poor phase. The preset work is concerned with the effect of the fluid phase separation upon addition of F atoms in the system. Our study shows that F atoms mainly appear as a constituent of HF in a N{sub 2}-poor fluid phase up to a certain pressure beyond which they occur as CF{sub 4} in a N{sub 2}-rich phase and that the phase separation may be abrupt in thermodynamic sense. The pressure at the phase boundary can occur at about 30 GPa at 3000 K and about 10 GPa to 20 GPa at 1000 K.Some of these ranges maybe accessible by present-day experimental high-pressure techniques. We discuss implications of this study to detonation physics.

  3. Phase separation in biological membranes: integration of theory and experiment

    PubMed Central

    Elson, Elliot L.; Fried, Eliot; Dolbow, John E.; Genin, Guy M.

    2013-01-01

    Lipid bilayer model membranes can undergo transitions between ordered and disordered phases, and membranes that contain a mixture of lipid species can undergo phase separations. Studies of these transformations are of interest for what they can tell us about the interaction energies of lipid molecules of different species and conformations. Nanoscopic phases can provide a model for membrane rafts, which have important biological functions in cell membranes. Important questions are whether lipid nanodomains can exist in stable equilibrium in membranes and what is the distribution of their sizes in membranes of different composition. It is also important to know the lifetimes of nanodomains. Theoretical methods have supplied much important information on these questions, but better experimental methods are needed to detect and characterize nanodomains under normal membrane conditions. This review summarizes linkages between theoretical and experimental studies of phase separation in lipid bilayer model membranes. PMID:20192775

  4. Phase separation in biological membranes: integration of theory and experiment.

    PubMed

    Elson, Elliot L; Fried, Eliot; Dolbow, John E; Genin, Guy M

    2010-01-01

    Lipid bilayer model membranes that contain a single lipid species can undergo transitions between ordered and disordered phases, and membranes that contain a mixture of lipid species can undergo phase separations. Studies of these transformations are of interest for what they can tell us about the interaction energies of lipid molecules of different species and conformations. Nanoscopic phases (<200 nm) can provide a model for membrane rafts, specialized membrane domains enriched in cholesterol and sphingomyelin, which are believed to have essential biological functions in cell membranes. Crucial questions are whether lipid nanodomains can exist in stable equilibrium in membranes and what is the distribution of their sizes and lifetimes in membranes of different composition. Theoretical methods have supplied much information on these questions, but better experimental methods are needed to detect and characterize nanodomains under normal membrane conditions. This review summarizes linkages between theoretical and experimental studies of phase separation in lipid bilayer model membranes.

  5. Phase Separation kinetics in an Fe-Cr-Al alloy

    SciTech Connect

    Capdevila, C.; Miller, Michael K; Chao, J.

    2012-01-01

    The {alpha}-{alpha}{prime} phase separation kinetics in a commercial Fe-20 wt.% Cr-6 wt.% Al oxide dispersion-strengthened PM 2000{trademark} steel have been characterized with the complementary techniques atom probe tomography and thermoelectric power measurements during isothermal aging at 673, 708, and 748 K for times up to 3600 h. A progressive decrease in the Al content of the Cr-rich {alpha}{prime} phase was observed at 708 and 748 K with increasing time, but no partitioning was observed at 673 K. The variation in the volume fraction of the {alpha}{prime} phase well inside the coarsening regime, along with the Avrami exponent 1.2 and activation energy 264 kJ mol{sup -1}, obtained after fitting the experimental results to an Austin-Rickett type equation, indicates that phase separation in PM 2000{trademark} is a transient coarsening process with overlapping nucleation, growth, and coarsening stages.

  6. DUAL PHASE MEMBRANE FOR HIGH TEMPERATURE CO2 SEPARATION

    SciTech Connect

    Jerry Y.S. Lin

    2002-12-01

    This project is aimed at synthesis of a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Metal-carbonate dual-phase membranes were prepared by the direct infiltration method and the synthesis conditions were optimized. The dual-phase membranes are gas-tight with helium permeance about six orders of magnitude lower than that for the metal support. Efforts were made to test seals for permeation and separation experiments for dual-phase membrane at the intermediate temperature range (about 500 C) under oxidizing atmosphere. An effective new permeation cell with a metal seal was designed, fabricated and tested. The permeation setup provided leak-free sealing for the dual-phase membranes under the desired operation conditions. Though the reliable data showing high permeance for carbon dioxide with oxygen for the prepared metal-carbonate dual phase membrane has not been measured, the research efforts in improving membrane synthesis and setting up a new permeation cell with suitable seal have made it closer for one to demonstrate good dual-phase membranes for high temperature carbon dioxide separation. Research efforts were also directed towards preparation of a new ceramic-carbonate dual-phase membrane. Porous lanthanum cobaltite (LC) perovskite type oxide ceramic support with oxidation resistance better than the metal support and high electronic conductivity (1300-1500 S/cm in 400-600 C), was prepared and studied as an alternative support for the dual-phase carbonate membranes. The LC powder was found not reactive with the carbonate at 600 C. The porous LC disks have helium permeance and pore diameter smaller than the metal support but larger than the common {alpha}-alumina support. These results show promise to use the LC support for preparation of oxidation resistant dual-phase carbonate membranes.

  7. Ruthenium Behavior at Phase Separation of Borosilicate Glass-12259

    SciTech Connect

    Enokida, Youichi; Sawada, Kayo

    2012-07-01

    The Rokkasho reprocessing plant (RRP) located in Aomori, Japan, vitrifies high level waste (HLW) into a borosilicate glass. The HLW is generated from the reprocessing of spent fuel and contains ruthenium (Ru) and other platinum group metals (PGMs). Based on the recent consequences after a huge earthquake that occurred in Japan, a hypothetical blackout was postulated for the RRP to address additional safety analysis requirements. During a prolonged blackout, the borosilicate glass could phase separate due to cooling of the glass in the melter. The Ru present in the glass matrix could migrate into separate phases and impact the durability of the borosilicate glass. The durability of the glass is important for quality assurance and performance assessment of the vitrified HLW. A fundamental study was performed at an independent university to understand the impact of a prolonged blackout. Simulated HLW glasses were prepared for the RRP, and the Ru behavior in phase separated glasses was studied. The simulated HLW glasses contained nonradioactive elements and PGMs. The glass compositions were then altered to enhance the formation of the phase-separated glasses when subjected to thermal treatment at 700 deg. C for 24 hours. The synthesized simulated glasses contained 1.1 % Ru by weight as ruthenium dioxide (RuO{sub 2}). A portion of the RuO{sub 2} formed needle-shaped crystals in the glass specimens. After the thermal treatment, the glass specimen had separated into two phases. One of the two phases was a B{sub 2}O{sub 3} rich phase, and the other phase was a SiO{sub 2} rich phase. The majority of the chemical species in the B{sub 2}O{sub 3} rich phase was leached away with the Material Characterization Center-3 (MCC-3) protocol standardized by the Pacific Northwest National Laboratory using an aqueous low-concentrated nitric acid solution, but the leaching of the Ru fraction was very limited; less than 1% of the original Ru content. The Ru leaching was much less than

  8. Modeling Human Population Separation History Using Physically Phased Genomes

    PubMed Central

    Song, Shiya; Sliwerska, Elzbieta; Emery, Sarah; Kidd, Jeffrey M.

    2017-01-01

    Phased haplotype sequences are a key component in many population genetic analyses since variation in haplotypes reflects the action of recombination, selection, and changes in population size. In humans, haplotypes are typically estimated from unphased sequence or genotyping data using statistical models applied to large reference panels. To assess the importance of correct haplotype phase on population history inference, we performed fosmid pool sequencing and resolved phased haplotypes of five individuals from diverse African populations (including Yoruba, Esan, Gambia, Maasai, and Mende). We physically phased 98% of heterozygous SNPs into haplotype-resolved blocks, obtaining a block N50 of 1 Mbp. We combined these data with additional phased genomes from San, Mbuti, Gujarati, and Centre de’Etude du Polymorphism Humain European populations and analyzed population size and separation history using the pairwise sequentially Markovian coalescent and multiple sequentially Markovian coalescent models. We find that statistically phased haplotypes yield a more recent split-time estimation compared with experimentally phased haplotypes. To better interpret patterns of cross-population coalescence, we implemented an approximate Bayesian computation approach to estimate population split times and migration rates by fitting the distribution of coalescent times inferred between two haplotypes, one from each population, to a standard isolation-with-migration model. We inferred that the separation between hunter-gatherer populations and other populations happened ∼120–140 KYA, with gene flow continuing until 30–40 KYA; separation between west-African and out-of-African populations happened ∼70–80 KYA; while the separation between Maasai and out-of-African populations happened ∼50 KYA. PMID:28049708

  9. Phase separation in transparent liquid-liquid miscibility gap systems

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Bhat, B. N.; Laub, R. J.

    1979-01-01

    A program to be carried out on transparent liquid-phase miscibility gap materials was developed for the purpose of acquiring additional insight into the separation process occurring in these systems. The transparency feature allows the reaction to be viewed directly through light scattering and holographic methods.

  10. Demixing kinetics of phase separated polymer solutions in microgravity

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.; Bamberger, S. B.; Harris, J. M.; Vanalstine, J.; Snyder, R. S.

    1988-01-01

    Phase separated solutions of two neutral polymers in buffer provide a useful and versatile medium for the partition separation of biological cells. However, the efficiency of such separations is orders of magnitude lower than the thermodynamic limit. To test the hypothesis that this inefficiency is at least partially due to the convection and sedimentation that occur during the gravity driven demixing that follows introduction of cells to the systems, a series of experiments were begun aimed at performing cell partition in a low g environment. Demixing of isopycnic three polymer solvent systems was studied, experiments were performed on KC-135 aircraft and one shuttle middeck experiment was completed. Analysis of the results of these experiments and comparisons with the predictions of scaling relations for the dependence of phase domain size on time, derived for a number of possible demixing mechanisms, are presented.

  11. Diagnostic immunoassay by solid phase separation for digoxin

    SciTech Connect

    Grenier, F.C.; Pry, T.A.; Kolaczkowski, L.

    1988-11-29

    A method is described for conducting a diagnostic immunoassay for digoxin, comprising: (a) forming a reaction mixture of a test sample with a molar excess of labeled anti-digoxin antibodies whereby the labeled antibodies are capable of forming complex with digoxin present in the sample; (b) contacting the reaction mixture with a solid phase material having immobilized thereon a compound; (c) separating the solid phase material from the reaction mixture; and (d) determining the presence of digoxin in the test sample by measuring the amount of complex present in the liquid phase.

  12. Assemblages: Functional units formed by cellular phase separation

    PubMed Central

    Wright, Peter E.

    2014-01-01

    The partitioning of intracellular space beyond membrane-bound organelles can be achieved with collections of proteins that are multivalent or contain low-complexity, intrinsically disordered regions. These proteins can undergo a physical phase change to form functional granules or other entities within the cytoplasm or nucleoplasm that collectively we term “assemblage.” Intrinsically disordered proteins (IDPs) play an important role in forming a subset of cellular assemblages by promoting phase separation. Recent work points to an involvement of assemblages in disease states, indicating that intrinsic disorder and phase transitions should be considered in the development of therapeutics. PMID:25179628

  13. Binary mixtures of polyhedral nanoparticles: from phase separation to superstructures

    NASA Astrophysics Data System (ADS)

    Khadilkar, Mihir; Agarwal, Umang; Escobedo, Fernando

    2014-03-01

    Polyhedral nanoparticles have emerged as important model systems for both fundamental studies of entropic self-assembly as well as material design. The mixing of more than one shape provides a promising strategy towards achieving a greater variety of structures and properties. We explore this with the study of the phase behavior of binary mixtures of hard convex polyhedra having similar sizes but different shapes. Choosing representative particle shapes from those readily synthesizable, we find that the phase behavior of such mixtures is dependent on the interplay of mixing and packing entropy, which can give rise to miscible or phase-separated states. While expectedly many of the binary systems studied exhibit phase separation at high pressures due to the incompatible pure-component crystal structures, our study shows that the essential qualitative trends in miscibility and phase separation can be correlated to properties of the pure components, such as the relative values of the order-disorder transition pressure of each component. However, the relative size ratios and the presence of mesophases for the pure-component systems are also critical in aiding the formation of fully miscible blends of novel plastic crystalline superstructures.

  14. Analysis of Phase Separation in Czochralski Grown Single Crystal Ilmenite

    NASA Technical Reports Server (NTRS)

    Wilkins, R.; Powell, Kirk St. A.; Loregnard, Kieron R.; Lin, Sy-Chyi; Muthusami, Jayakumar; Zhou, Feng; Pandey, R. K.; Brown, Geoff; Hawley, M. E.

    1998-01-01

    Ilmenite (FeTiOs) is a wide bandgap semiconductor with an energy gap of 2.58 eV. Ilmenite has properties suited for radiation tolerant applications, as well as a variety of other electronic applications. Single crystal ilmenite has been grown from the melt using the Czochralski method. Growth conditions have a profound effect on the microstructure of the samples. Here we present data from a variety of analytical techniques which indicate that some grown crystals exhibit distinct phase separation during growth. This phase separation is apparent for both post-growth annealed and unannealed samples. Under optical microscopy, there appear two distinct areas forming a matrix with an array of dots on order of 5 pm diameter. While appearing bright in the optical micrograph, atomic force microscope (AFM) shows the dots to be shallow pits on the surface. Magnetic force microscope (MFM) shows the dots to be magnetic. Phase identification via electron microprobe analysis (EMPA) indicates two major phases in the unannealed samples and four in the annealed samples, where the dots appear to be almost pure iron. This is consistent with micrographs taken with a scanning probe microscope used in the magnetic force mode. Samples that do not exhibit the phase separation have little or no discernible magnetic structure detectable by the MFM.

  15. Probing quantum frustrated systems via factorization of the ground state.

    PubMed

    Giampaolo, Salvatore M; Adesso, Gerardo; Illuminati, Fabrizio

    2010-05-21

    The existence of definite orders in frustrated quantum systems is related rigorously to the occurrence of fully factorized ground states below a threshold value of the frustration. Ground-state separability thus provides a natural measure of frustration: strongly frustrated systems are those that cannot accommodate for classical-like solutions. The exact form of the factorized ground states and the critical frustration are determined for various classes of nonexactly solvable spin models with different spatial ranges of the interactions. For weak frustration, the existence of disentangling transitions determines the range of applicability of mean-field descriptions in biological and physical problems such as stochastic gene expression and the stability of long-period modulated structures.

  16. Phase separation dynamics during Myxococcus xanthus fruiting body formation

    NASA Astrophysics Data System (ADS)

    Liu, Guannan; Bahar, Fatmagul; Patch, Adam; Thutupalli, Shashi; Yllanes, David; Marchetti, M. Cristina; Welch, Roy; Shaevitz, Joshua

    Many living systems take advantage of collective behavior for group survival. We use the soil-dwelling bacterium Myxococcus xanthus as a model to study out-of-equilibrium phase separation during fruiting body formation. M. xanthus cells have the ability to glide on solid surfaces and reverse their direction periodically. When starved, M. xanthus cells aggregate together and form structures called fruiting bodies, inside of which cells sporulate to survive stressful conditions. We show that at high cell density the formation of fruiting bodies is a phase separation process. From experimental data that combines single-cell tracking, population-scale imaging, mutants, and drug applications, we construct the phase diagram of M. xanthus in the space of Péclet number and cell density. When wild type cells are starved, we find that they actively increase their Péclet number by modulating gliding speed and reversal frequency which induces a phase separation from a gas-like state to an aggregated fruiting body state.

  17. Phase separation in solutions with specific and nonspecific interactions

    SciTech Connect

    Jacobs, William M.; Frenkel, Daan; Oxtoby, David W.

    2014-05-28

    Protein solutions, which tend to be thermodynamically stable under physiological conditions, can demix into protein-enriched and protein-depleted phases when stressed. Using a lattice-gas model of proteins with both isotropic and specific, directional interactions, we calculate the critical conditions for phase separation for model proteins with up to four patches via Monte Carlo simulations and statistical associating fluid theory. Given a fixed specific interaction strength, the critical value of the isotropic energy, which accounts for dispersion forces and nonspecific interactions, measures the stability of the solution with respect to nonspecific interactions. Phase separation is suppressed by the formation of protein complexes, which effectively passivate the strongly associating sites on the monomers. Nevertheless, we find that protein models with three or more patches can form extended aggregates that phase separate despite the assembly of passivated complexes, even in the absence of nonspecific interactions. We present a unified view of the critical behavior of model fluids with anisotropic interactions, and we discuss the implications of these results for the thermodynamic stability of protein solutions.

  18. Re-entrant phase behavior for systems with competition between phase separation and self-assembly.

    PubMed

    Reinhardt, Aleks; Williamson, Alexander J; Doye, Jonathan P K; Carrete, Jesús; Varela, Luis M; Louis, Ard A

    2011-03-14

    In patchy particle systems where there is a competition between the self-assembly of finite clusters and liquid-vapor phase separation, re-entrant phase behavior can be observed, with the system passing from a monomeric vapor phase to a region of liquid-vapor phase coexistence and then to a vapor phase of clusters as the temperature is decreased at constant density. Here, we present a classical statistical mechanical approach to the determination of the complete phase diagram of such a system. We model the system as a van der Waals fluid, but one where the monomers can assemble into monodisperse clusters that have no attractive interactions with any of the other species. The resulting phase diagrams show a clear region of re-entrance. However, for the most physically reasonable parameter values of the model, this behavior is restricted to a certain range of density, with phase separation still persisting at high densities.

  19. Enantiomeric phase separation in a lattice gas model: Guggenheim approximation

    NASA Astrophysics Data System (ADS)

    Huckaby, Dale A.; Shinmi, Masato; Ausloos, Marcel; Clippe, Paulette

    1986-05-01

    We consider a lattice gas in which the two enantiomeric forms of a tetrahedral molecule, consisting of a central carbon atom bonded to four different groups A, B, G, and H, are adsorbed onto a triangular lattice, such that the carbon atom is above a lattice site, the three bonds to A, B, and G point toward neighboring lattice sites, and the bond to H points perpendicular to and away from the plane of the lattice. For a certain choice of intermolecular interactions, such as may exist between the zwitterion forms of an amino acid, the phase diagram was investigated using a Guggenheim approximation with two order parameters. Enantiomeric phase separation into two symmetric condensed phases occurs at low temperatures. These condensed phases become a single racemic condensed phase at a critical line, and they are in equilibrium with a racemic gas phase along a line of triple points. These two lines coincide at a critical endpoint. The racemic condensed and gas phases are in equilibrium along a two phase coexistence line which begins at the critical endpoint and ends at a critical point. No tricritical point was found in the model for the special choice of interactions studied.

  20. Growth and Morphology of Phase Separating Supercritical Fluids

    NASA Technical Reports Server (NTRS)

    Hegseth, John; Beysens, Daniel; Perrot, Francoise; Nikolayev, Vadim; Garrabos, Yves

    1996-01-01

    The scientific objective is to study the relation between the morphology and the growth kinetics of domains during phase separation. We know from previous experiments performed near the critical point of pure fluids and binary liquids that there are two simple growth laws at late times. The 'fast' growth appears when the volumes of the phases are nearly equal and the droplet pattern is interconnected. In this case the size of the droplets grows linearly in time. The 'slow' growth appears when the pattern of droplets embedded in the majority phase is disconnected. In this case the size of the droplets increases in proportion to time to the power 1/3. The volume fraction of the minority phase is a good candidate to determine this change of behavior. All previous attempts to vary the volume fraction in a single experimental cell have failed because of the extreme experimental difficulties.

  1. Phase separation of polymer thin films and some applications

    NASA Astrophysics Data System (ADS)

    Zhu, Shaoming

    Phase separation of polymer thin film is a common issue in polymer thin film application. The existence of surface and surfactant are understood to play an important role in thin film final topography. In chapter two, the configuration of polymer blend thin film phase separation on cobalt substrate with PMMA phase forming column structure, and PS phase encapsulating the PMMA phase was used as resist mask to transfer the topographical feature to cobalt thin film. Isolated near spherical single and multi domain magnetic islands were obtained. The island made using this method had a broad single domain range from below 1000 to 5000A. In chapter three, when the polymer blend thin film was in bilayer configuration and diblock copolymer was added on the top layer, we found the confinement can increase the mixing of two homopolymers in highly incompatible polymer blends. By affecting the formation of micelles, the copolymers are forced to the interface between the two homopolymer phases where they reduce the interfacial tension to zero and form a microemulsion. Our findings have two important implications: first, they elucidate the role entropy plays in determining the phase behaviour of confined polymer blends and second, they offer a simple pathway to create thin film coatings with precisely controlled properties and surfaces. In chapter four, the kinetics process of microemulsion formation in confinement configuration has been analyzed. The microemulsion formation proceeded at initial stage by capillary wave, then it followed the growth regime t1/3 and lnt, then followed a more slow growth regime (lnt).56 or (lnt).60 till finally reached equilibrium, when the structure was frozen. In chapter five, we study the evolution of the morphologies of polymer blend thin films on silicon, cobalt, and gold substrates. In asymmetrical system, the substrate surface energy determined the wetting degree of the substrate preferring phases. In chapter six, we present a novel method for

  2. Phase separation of metallic hydrogen-helium alloys

    NASA Technical Reports Server (NTRS)

    Straus, D. M.; Ashcroft, N. W.; Beck, H.

    1977-01-01

    Calculations are presented for the thermodynamic functions and phase-separation boundaries of solid metallic hydrogen-helium alloys at temperatures between zero and 19,000 K and at pressures between 15 and 90 Mbar. Expressions for the band-structure energy of a randomly disordered alloy (including third order in the electron-ion interaction) are derived and evaluated. Short- and long-range orders are included by the quasi-chemical method, and lattice dynamics in the virtual-crystal harmonic approximation. It is concluded that at temperatures below 4000 K, there is essentially complete phase separation of hydrogen-helium alloys and that a miscibility gap remains at the highest temperatures and pressures considered. The relevance of these results to models of the deep interior of Jupiter is briefly discussed.

  3. Phase separation of metallic hydrogen-helium alloys

    NASA Technical Reports Server (NTRS)

    Straus, D. M.; Ashcroft, N. W.; Beck, H.

    1976-01-01

    Calculations are presented for the thermodynamic functions and phase separation boundaries of solid metallic hydrogen helium alloys at temperatures between 0 K and 19,000 K and at pressures between 15 and 90 megabars. Expressions for the band structure energy of a randomly disordered alloy (including third order in the electron ion interaction) are derived and evaluated. Short and long range order are included by the quasi-chemical method, and lattice dynamics in the virtual crystal harmonic approximation. We conclude that at temperatures below 4,000 K there is complete phase separation of hydrogen helium alloys, and that a miscibility gap remains at the highest temperatures and pressures considered. The relevance of these results to models of the deep interior of Jupiter is briefly discussed.

  4. Kinetics of motility-induced phase separation and swim pressure

    NASA Astrophysics Data System (ADS)

    Patch, Adam; Yllanes, David; Marchetti, M. Cristina

    2017-01-01

    Active Brownian particles (ABPs) represent a minimal model of active matter consisting of self-propelled spheres with purely repulsive interactions and rotational noise. Here we examine the pressure of ABPs in two dimensions in both closed boxes and systems with periodic boundary conditions and show that its nonmonotonic behavior with density is a general property of ABPs and is not the result of finite-size effects. We correlate the time evolution of the mean pressure towards its steady-state value with the kinetics of motility-induced phase separation. For parameter values corresponding to phase-separated steady states, we identify two dynamical regimes. The pressure grows monotonically in time during the initial regime of rapid cluster formation, overshooting its steady-state value and then quickly relaxing to it, and remains constant during the subsequent slower period of cluster coalescence and coarsening. The overshoot is a distinctive feature of active systems.

  5. Fibril Formation and Phase Separation in Aqueous Cellulose Ethers

    NASA Astrophysics Data System (ADS)

    Maxwell, Amanda; Schmidt, Peter; McAllister, John; Lott, Joseph; Bates, Frank; Lodge, Timothy

    Aqueous solutions of many cellulose ethers are known to undergo thermoreversible gelation and phase separation upon heating to form turbid hydrogels, but the mechanism and resulting structures have not been well understood. Turbidity, light scattering and small-angle neutron scattering (SANS) are used to show that hydroxypropyl methylcellulose (HPMC) chains are dissolved in water below 50 °C and undergo phase separation at higher temperatures. At 70 °C, at sufficiently high concentrations in water, HPMC orders into fibrillar structures with a well-defined radius of 18 +/- 2 nm, as characterized by cryogenic transmission electron microscopy and SANS. The HPMC fibril structure is independent of concentration and heating rate. However, HPMC fibrils do not form a percolating network as readily as is seen in methylcellulose, resulting in a lower hot-gel modulus, as demonstrated by rheology.

  6. Correlated lateral phase separations in stacks of lipid membranes

    NASA Astrophysics Data System (ADS)

    Hoshino, Takuma; Komura, Shigeyuki; Andelman, David

    2015-12-01

    Motivated by the experimental study of Tayebi et al. [Nat. Mater. 11, 1074 (2012)] on phase separation of stacked multi-component lipid bilayers, we propose a model composed of stacked two-dimensional Ising spins. We study both its static and dynamical features using Monte Carlo simulations with Kawasaki spin exchange dynamics that conserves the order parameter. We show that at thermodynamical equilibrium, due to strong inter-layer correlations, the system forms a continuous columnar structure for any finite interaction across adjacent layers. Furthermore, the phase separation shows a faster dynamics as the inter-layer interaction is increased. This temporal behavior is mainly due to an effective deeper temperature quench because of the larger value of the critical temperature, Tc, for larger inter-layer interaction. When the temperature ratio, T/Tc, is kept fixed, the temporal growth exponent does not increase and even slightly decreases as a function of the increased inter-layer interaction.

  7. GPU accelerated numerical simulations of viscoelastic phase separation model.

    PubMed

    Yang, Keda; Su, Jiaye; Guo, Hongxia

    2012-07-05

    We introduce a complete implementation of viscoelastic model for numerical simulations of the phase separation kinetics in dynamic asymmetry systems such as polymer blends and polymer solutions on a graphics processing unit (GPU) by CUDA language and discuss algorithms and optimizations in details. From studies of a polymer solution, we show that the GPU-based implementation can predict correctly the accepted results and provide about 190 times speedup over a single central processing unit (CPU). Further accuracy analysis demonstrates that both the single and the double precision calculations on the GPU are sufficient to produce high-quality results in numerical simulations of viscoelastic model. Therefore, the GPU-based viscoelastic model is very promising for studying many phase separation processes of experimental and theoretical interests that often take place on the large length and time scales and are not easily addressed by a conventional implementation running on a single CPU.

  8. Correlated lateral phase separations in stacks of lipid membranes.

    PubMed

    Hoshino, Takuma; Komura, Shigeyuki; Andelman, David

    2015-12-28

    Motivated by the experimental study of Tayebi et al. [Nat. Mater. 11, 1074 (2012)] on phase separation of stacked multi-component lipid bilayers, we propose a model composed of stacked two-dimensional Ising spins. We study both its static and dynamical features using Monte Carlo simulations with Kawasaki spin exchange dynamics that conserves the order parameter. We show that at thermodynamical equilibrium, due to strong inter-layer correlations, the system forms a continuous columnar structure for any finite interaction across adjacent layers. Furthermore, the phase separation shows a faster dynamics as the inter-layer interaction is increased. This temporal behavior is mainly due to an effective deeper temperature quench because of the larger value of the critical temperature, Tc, for larger inter-layer interaction. When the temperature ratio, T/Tc, is kept fixed, the temporal growth exponent does not increase and even slightly decreases as a function of the increased inter-layer interaction.

  9. Tc anisotropy and phase separation in strained Vanadium Dioxide films

    NASA Astrophysics Data System (ADS)

    Liu, Mengkun; Wagner, Martin; Abreu, Elsa; Kittiwatanakul, Salinporn; McLeod, Alexander; Goldflam, Michael; Fei, Zhe; Dai, Siyuan; Fogler, Michael; Lu, Jiwei; Wolf, Stuart; Averitt, Richard; Basov, D. N.

    2013-03-01

    We report Infrared near field study on strain induced transition temperature (Tc) anisotropy in vanadium dioxide (VO2) films via direct visualization of a spontaneous structural and electronic phase separation. The films are epitaxially grown on [110]R or [100]R TiO2 substrates and exhibit large uniaxial strain. By mapping the film topography with AFM and electronic percolation with Infrared scattering scanning near-field optical microscopy, a temperature dependent electron-lattice correlation can be clearly observed. Our work sheds a new light onto the nature of the Tc anomaly in metal-insulator transition and leads to the possibility of controlling the material's properties through strain induced phase separation.

  10. Separation of granulocytes from whole blood by leukoadhesion, phase 1

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Capillary glass tubes are investigated for the separation and retrieval of large quantities of viable granulocytes and monocytes from whole blood on a continuous basis from a single donor. This effort represented the feasibility demonstration of a three phase program for development of a capillary tube cell separation device. The activity included the analysis and parametric laboratory testing with subscale models required to design a prototype device. Capillary tubes 40 cm long with a nominal 0.030 cm internal diameter yielded the highest total process efficiency. Recovery efficiencies as high as 89% of the adhering cell population were obtained. Granulocyte phagocytosis of latex particles indicated approximately 90% viability. Monocytes recovered from the separation column retained their capability to stimulate human bone marrow colony growth, as demonstrated in an in vitro cell culture assay.

  11. Rationale for two phase polymer system microgravity separation experiments

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.; Bamberger, S. B.; Harris, J. M.; Vanalstine, J.

    1984-01-01

    The two-phase systems that result when aqueous solutions of dextran and poly(ethylene glycol) are mixed at concentrations above a few percent are discussed. They provide useful media for the partition and isolation of macromolecules and cell subpopulations. By manipulating their composition, separations based on a variety of molecular and surface properties are achieved, including membrane hydrophobic properties, cell surface charge, and membrane antigenicity. Work on the mechanism of cell partition shows there is a randomizing, nonthermal energy present which reduces separation resolution. This stochastic energy is probably associated with hydrodynamic interactions present during separation. Because such factors should be markedly reduced in microgravity, a series of shuttle experiments to indicate approaches to increasing the resolution of the procedure are planned.

  12. Novel Resistive Switching Behavior in Phase Separated Manganites

    NASA Astrophysics Data System (ADS)

    Guo, Hangwen; Ward, T. Zac; Sun, Dali; Snijders, Paul C.; Gai, Zheng; Shen, Jian

    2011-03-01

    Electronic phase separation plays a key role in many novel phenomena in complex materials. Manganites are a prime example of this class of materials and have recently come under increase scrutiny for possible application in resistive random-access memory (RRAM) technology. Here, we will discuss our recent work on spatially confined La5/8-xPrxCa3/8MnO3. We have discovered that it is possible to drive single electronic domain formation/annihilation through electric field pulsing. By measuring the I-V curve, we find such resistive switching is different from normal RRAM mechanisms in manganites and is closely related to the nature of electronic phase separation. These findings open these systems to a new understanding of the nature of electronic phase separation and begin the development of manganites for future applications in RRAM devices. Research sponsored by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy.

  13. Phase separated microstructure and dynamics of polyurethane elastomers under strain

    NASA Astrophysics Data System (ADS)

    Iacob, Ciprian; Padsalgikar, Ajay; Runt, James

    The molecular mobility of polyurethane elastomers is of the utmost importance in establishing physical properties for uses ranging from automotive tires and shoe soles to more sophisticated aerospace and biomedical applications. In many of these applications, chain dynamics as well as mechanical properties under external stresses/strains are critical for determining ultimate performance. In order to develop a more complete understanding of their mechanical response, we explored the effect of uniaxial strain on the phase separated microstructure and molecular dynamics of the elastomers. We utilize X-ray scattering to investigate soft segment and hard domain orientation, and broadband dielectric spectroscopy for interrogation of the dynamics. Uniaxial deformation is found to significantly perturb the phase-separated microstructure and chain orientation, and results in a considerable slowing down of the dynamics of the elastomers. Attenuated total reflectance Fourier transform infrared spectroscopy measurements of the polyurethanes under uniaxial deformation are also employed and the results are quantitatively correlated with mechanical tensile tests and the degree of phase separation from small-angle X-ray scattering measurements.

  14. Evaluation of phase separator number in hydrodesulfurization (HDS) unit

    NASA Astrophysics Data System (ADS)

    Jayanti, A. D.; Indarto, A.

    2016-11-01

    The removal process of acid gases such as H2S in natural gas processing industry is required in order to meet sales gas specification. Hydrodesulfurization (HDS)is one of the processes in the refinery that is dedicated to reduce sulphur.InHDS unit, phase separator plays important role to remove H2S from hydrocarbons, operated at a certain pressure and temperature. Optimization of the number of separator performed on the system is then evaluated to understand the performance and economics. From the evaluation, it shows that all systems were able to meet the specifications of H2S in the desired product. However, one separator system resulted the highest capital and operational costs. The process of H2S removal with two separator systems showed the best performance in terms of both energy efficiency with the lowest capital and operating cost. The two separator system is then recommended as a reference in the HDS unit to process the removal of H2S from natural gas.

  15. Uphill diffusion and phase separation in partially miscible multicomponent mixtures

    NASA Astrophysics Data System (ADS)

    He, Ping; Raghavan, Ashwin; Ghoniem, Ahmed

    2015-11-01

    The partially miscible multicomponent mixtures, which are frequently encountered in green chemistry processes, often exhibit complicated behaviors, and are critical to the production rate, energy efficiency, and pollution controls. Recent studies have been mainly focused on phase behaviors. However, the coupled phase equilibrium and transport process, which may be the answer to phase separations observed in experiments, is not well researched. Here, we present a numerical and theoretical study on coupled mixing of heavy oil and supercritical water, and the results of our state-of-art modeling agree with experimental measurements. We find that due to the non-ideal diffusion driving force, (1) strong uphill diffusion of heavy oil fractions occurs, (2) a new heavy oil phase is separated starting from the plait point, and heavy fractions become highly concentrated, and (3) water diffusion initially overshoots in oil, and is expelled lately. Finally, we conclude our analysis applicable to different molecules and conditions. The authors thank Saudi Aramco for supporting this work (contract number 6600023444).

  16. Thermodynamics of the motility-induced phase separation

    NASA Astrophysics Data System (ADS)

    Solon, Alexandre; Stenhammar, Joachim; Cates, Michael; Tailleur, Julien

    Self-propelled particles are known to accumulate in regions of space where their velocity is lowered. In addition, if their velocity diminishes when the local density increases (for example due to crowding effects), a positive feedback loop leads to the now well-established motility-induced phase separation (MIPS) between a dense immotile phase and a dilute motile phase. Understanding the phase equilibrium of MIPS is still a matter of debate. Although, depending on the models used to study the transition, a chemical potential or a pressure can be defined, these quantities do not play their usual thermodynamic role. In particular, the usual common tangent or equal-area constructions fail in these systems. Indeed, we will show that describing the phase equilibrium of MIPS necessitates generalized thermodynamics that include non-equilibrium contributions. This approach allows us to predict correctly the phase diagram of MIPS and to gain insight into the thermodynamics of active systems. It also sheds light on the (in)equivalence of statistical ensembles for these systems, paving the way for more efficient computational studies.

  17. Separation of peptides on superficially porous particle based macrocyclic glycopeptide liquid chromatography stationary phases: consideration of fast separations.

    PubMed

    Wimalasinghe, Rasangi M; Breitbach, Zachary S; Lee, Jauh T; Armstrong, Daniel W

    2017-03-01

    Macrocyclic glycopeptide based liquid chromatography stationary phases are known for their highly selective peptide separations. Fast and ultrafast (t R < 1 min) high-efficiency separations were achieved with superficially porous particle (SPP)-based stationary phases. Separations of pharmaceutically important classes of peptides such as enkephalins and bradykinins have been achieved in less than 5 min in isocratic elution modes. Selectivity for peptides structurally similar to one another was increased with use of teicoplanin-based stationary phases compared with commercial C18 stationary phases. Ultrafast isocratic separations of structurally related peptides were achieved with teicoplanin- and vancomycin-based short SPP columns. Acidic mobile phases produced better separations. Ammonium formate was the optimal mobile phase buffer additive. Use of an appropriate combination of a macrocyclic glycopeptide stationary phase and a mobile phase permits faster and more electrospray ionization mass spectrometry compatible isocratic separations than previous gradient approaches. The tryptic peptide separation characteristics of the teicoplanin stationary phase are demonstrated. Additionally, compared with commercial C18 stationary phases, teicoplanin showed tryptic peptide separations with different selectivities. Graphical Abstract Ultrafast separation of enkephalin peptide epimers.

  18. Quadruple-junction lattice coherency and phase separation in a binary-phase system

    PubMed Central

    Chung, Sung-Yoon; Choi, Si-Young; Kim, Jin-Gyu; Kim, Young-Min

    2015-01-01

    If each phase has an identical crystal structure and small misfit in the lattice parameters in a binary-phase crystalline system, coherent phase boundaries usually form during separation. Although there have been numerous studies on the effect of coherency elastic energy, no attempt has been made to demonstrate how the phase-separation behaviour varies when multiple interfaces meet at a junction. Here we show that a comprehensively different phase-separation morphology is induced, to release the high coherency strain confined to quadruple junctions. High-temperature in-situ transmission electron microscopy reveals that phase boundaries with a new crystallographic orientation emerge over twinned crystals to provide strain relaxation at quadruple junctions. The high coherency strain and the formation of different phase boundaries can be understood in terms of the force equilibrium between interface tensions at a junction point. Visualizing the quadruple points at atomic resolution, our observations emphasize the impact of multiple junctions on the morphology evolution during phase separation. PMID:26346223

  19. Macroscopic Phase Separation, Modulated Phases, and Microemulsions: A Unified Picture of Rafts

    PubMed Central

    Shlomovitz, Roie; Maibaum, Lutz; Schick, M.

    2014-01-01

    We simulate a simple phenomenological model describing phase behavior in a multicomponent membrane, a model capable of producing macroscopic phase separation, modulated phases, and microemulsions, all of which have been discussed in terms of raft phenomena. We show that one effect of thermal fluctuations on the mean-field phase diagram is that it permits a direct transition between either one of the coexisting liquid phases to a microemulsion. This implies that one system exhibiting phase separation can be related to a similar system exhibiting the heterogeneities characteristic of a microemulsion. The two systems could differ in their average membrane composition or in the relative compositions of their exoplasmic and cytoplasmic leaves. The model provides a unified description of these raft-associated phenomena. PMID:24806930

  20. The phase reversal phenomenon at flow separation and reattachment

    NASA Technical Reports Server (NTRS)

    Stack, J. Pete; Mangalam, S. M.; Kalburgi, V.

    1988-01-01

    Tests were conducted on two different airfoils, one of them in a low-turbulence tunnel, to detect laminar separation and turbulent reattachment locations. A 'nonintrusive' multielement sensor consisting of a large number of closely spaced individual nickel films was vacuum deposited on a thin substrate and bonded to the airfoil model surface. Each sensor element was a part of an independent constant temperature anemometer system. Time history as well as spectral analysis of signals from surface film gauges were used to determine the surface shear flow characteristics. A major breakthrough was achieved with the discovery of phase reversal in low-frequency dynamic shear stress signals across regions of flow separation and reattachment.

  1. Excitations from a chiral magnetized state of a frustrated quantum spin liquid

    SciTech Connect

    Garlea, Vasile O; Zheludev, Andrey I; Tsvelik, A.; Regnault, L.-P.; Habicht, Klaus; Kiefer, K.; Roessli, Bertrand

    2009-01-01

    We study excitations in weakly interacting pairs of quantum spin ladders coupled through geometrically frustrated bonds. The ground state is a disordered spin liquid, at high fields replaced by an ordered chiral helimagnetic phase. The spectra observed by high-field inelastic neutron scattering experiments on the prototype compound Sul Cu2Cl4 are qualitatively different from those in the previously studied frustration-free spin liquids. Beyond the critical field Hc = 3.7 T, the soft mode that drives the quantum phase transition spawns two separate excitations: a gapless Goldstone mode and a massive magnon. Additional massive quasiparticles are clearly visible below Hc, but are destroyed in the ordered phase. In their place one observes a sharply bound excitation continuum.

  2. Excitations from a Chiral Magnetized State of a Frustrated Quantum Spin Liquid

    SciTech Connect

    Zheludev, A.; Tsvelik, A.; Garlea, V.O.; Regnault, L.-P.; Habicht, K.; Kiefer, K.; Roessli, B.

    2009-12-15

    We study excitations in weakly interacting pairs of quantum spin ladders coupled through geometrically frustrated bonds. The ground state is a disordered spin liquid that at high fields is replaced by an ordered chiral helimagnetic phase. The spectra observed by high-field inelastic neutron scattering experiments on the prototype compound Sul-Cu{sub 2}Cl{sub 4} are qualitatively different from those in the previously studied frustration-free spin liquids. Beyond the critical field H{sub c} = 3.7 T, the soft mode that drives the quantum phase transition spawns two separate excitations: a gapless Goldstone mode and a massive magnon. Additional massive quasiparticles are clearly visible below H{sub c}, but are destroyed in the ordered phase. In their place one observes a sharply bound excitation continuum.

  3. Competing phases, phase separation, and coexistence in the extended one-dimensional bosonic Hubbard model

    SciTech Connect

    Batrouni, G. G.; Rousseau, V. G.; Scalettar, R. T.; Grémaud, B.

    2014-11-17

    Here, we study the phase diagram of the one-dimensional bosonic Hubbard model with contact (U) and near neighbor (V ) interactions focusing on the gapped Haldane insulating (HI) phase which is characterized by an exotic nonlocal order parameter. The parameter regime (U, V and μ) where this phase exists and how it competes with other phases such as the supersolid (SS) phase, is incompletely understood. We use the Stochastic Green Function quantum Monte Carlo algorithm as well as the density matrix renormalization group to map out the phase diagram. The HI exists only at = 1, the SS phase exists for a very wide range of parameters (including commensurate fillings) and displays power law decay in the one body Green function were our main conclusions. Additionally, we show that at fixed integer density, the system exhibits phase separation in the (U, V ) plane.

  4. Competing phases, phase separation, and coexistence in the extended one-dimensional bosonic Hubbard model

    DOE PAGES

    Batrouni, G. G.; Rousseau, V. G.; Scalettar, R. T.; ...

    2014-11-17

    Here, we study the phase diagram of the one-dimensional bosonic Hubbard model with contact (U) and near neighbor (V ) interactions focusing on the gapped Haldane insulating (HI) phase which is characterized by an exotic nonlocal order parameter. The parameter regime (U, V and μ) where this phase exists and how it competes with other phases such as the supersolid (SS) phase, is incompletely understood. We use the Stochastic Green Function quantum Monte Carlo algorithm as well as the density matrix renormalization group to map out the phase diagram. The HI exists only at = 1, the SS phase existsmore » for a very wide range of parameters (including commensurate fillings) and displays power law decay in the one body Green function were our main conclusions. Additionally, we show that at fixed integer density, the system exhibits phase separation in the (U, V ) plane.« less

  5. Self-assembly of amorphous biophotonic nanostructures by phase separation

    SciTech Connect

    Dufresne, Eric R.; Noh, Heeso; Saranathan, Vinodkumar; Mochrie, Simon G.J.; Cao, Hui; Prum, Richard O.

    2009-04-23

    Some of the most vivid colors in the animal kingdom are created not by pigments, but by wavelength-selective scattering of light from nanostructures. Here we investigate quasi-ordered nanostructures of avian feather barbs which produce vivid non-iridescent colors. These {beta}-keratin and air nanostructures are found in two basic morphologies: tortuous channels and amorphous packings of spheres. Each class of nanostructure is isotropic and has a pronounced characteristic length scale of variation in composition. These local structural correlations lead to strong backscattering over a narrow range of optical frequencies and little variation with angle of incidence. Such optical properties play important roles in social and sexual communication. To be effective, birds need to precisely control the development of these nanoscale structures, yet little is known about how they grow. We hypothesize that multiple lineages of birds have convergently evolved to exploit phase separation and kinetic arrest to self-assemble spongy color-producing nanostructures in feather barbs. Observed avian nanostructures are strikingly similar to those self-assembled during the phase separation of fluid mixtures; the channel and sphere morphologies are characteristic of phase separation by spinodal decomposition and nucleation and growth, respectively. These unstable structures are locked-in by the kinetic arrest of the {beta}-keratin matrix, likely through the entanglement or cross-linking of supermolecular {beta}-keratin fibers. Using the power of self-assembly, birds can robustly realize a diverse range of nanoscopic morphologies with relatively small physical and chemical changes during feather development.

  6. Frustrated Organic Solids Display Unexpected Gas Sorption

    SciTech Connect

    Thallapally, Praveen K.; Dalgarno, Scott J.; Atwood, Jerry L.

    2006-11-27

    Calixarene based organic solid can hold guests such as toluene and other organic molecules we have discovered a new type of material which believe involves a frustration of the solvate lattice as it moves toward the thermodynamically stable desolvated state. The intermediated phase with partial solvent content unexpectedly sorbs gases such as carbon dioxide and highly explosive acetylene deep inside the crystal lattice.

  7. Vapors-liquid phase separator. [infrared telescope heat sink

    NASA Technical Reports Server (NTRS)

    Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

    1980-01-01

    The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

  8. Nanopatterns by phase separation of patterned mixed polymer monolayers

    DOEpatents

    Huber, Dale L; Frischknecht, Amalie

    2014-02-18

    Micron-size and sub-micron-size patterns on a substrate can direct the self-assembly of surface-bonded mixed polymer brushes to create nanoscale patterns in the phase-separated mixed polymer brush. The larger scale features, or patterns, can be defined by a variety of lithographic techniques, as well as other physical and chemical processes including but not limited to etching, grinding, and polishing. The polymer brushes preferably comprise vinyl polymers, such as polystyrene and poly(methyl methacrylate).

  9. Phase/Shape Transitions and the Two Neutron Separation Energies

    SciTech Connect

    Zamfir, N. V.; Anghel, Sabina; Cata-Danil, G.

    2008-11-11

    We investigated the evolution of experimental two-neutron separation energies (S{sub 2n}) along the isotopic chains for the even-even nuclei. In order to enhance the sensitivity of our search, differential variation of the S{sub 2n} has been investigated. The emphasis is on finding nonmonotonic behaviors which can be correlated with phase/shape transition. Correlations of the ground state S{sub 2n} values with the excited states energies R{sub 4/2} ratio are also discussed.

  10. Anomalous Phase Separation Kinetics Observed in a Micelle Solution

    NASA Astrophysics Data System (ADS)

    Wilcoxon, Jess P.; Martin, James E.; Odinek, Judy

    1995-08-01

    We report a real-time, two-dimensional light scattering study of the evolution of structure in a two-component nonionic micelle system undergoing phase separation. We find that the structure of the domains is qualitatively similar to that observed in binary fluid systems, with some anomalies observed. However, compared to the Lifshitz-Slyozov prediction for simple binary fluids, the domain growth is unexpectedly slow. In fact, the growth kinetics can be empirically described as a stretched exponential approach to a pinned domain size. This anomalous behavior may be due to the ability of the spherical micelles to reorganize into more complex structures.

  11. Polymer-induced phase separation in suspensions of bacteria

    NASA Astrophysics Data System (ADS)

    Schwarz-Linek, J.; Dorken, G.; Winkler, A.; Wilson, L. G.; Pham, N. T.; French, C. E.; Schilling, T.; Poon, W. C. K.

    2010-03-01

    We study phase separation in suspensions of two unrelated species of rod-like bacteria, Escherichia coli and Sinorhizobium meliloti, induced by the addition of two different anionic polyelectrolytes, sodium polystyrene sulfonate or succinoglycan, the former being synthetic and the latter of natural origin. Comparison with the known behaviour of synthetic colloid-polymer mixtures and with simulations show that "depletion" (or, equivalently, "macromolecular crowding") is the dominant mechanism: exclusion of the non-adsorbing polymer from the region between two neighbouring bacteria creates an unbalanced osmotic force pushing them together. The implications of our results for understanding phenomena such as biofilm formation are discussed.

  12. Characterization of Phase Separation Propensity for Amorphous Spray Dried Dispersions.

    PubMed

    McNamara, Daniel; Yin, Shawn; Pan, Duohai; Crull, George; Timmins, Peter; Vig, Balvinder

    2017-02-06

    A generalized screening approach, applying isothermal calorimetry at 37 °C 100% RH, to formulations of spray dried dispersions (SDDs) for two active pharmaceutical ingredients (APIs) (BMS-903452 and BMS-986034) is demonstrated. APIs 452 and 034, with similar chemotypes, were synthesized and promoted during development for oral dosing. Both APIs were formulated as SDDs for animal exposure studies using the polymer hydroxypropylmethlycellulose acetyl succinate M grade (HPMCAS-M). 452 formulated at 30% (wt/wt %) was an extremely robust SDD that was able to withstand 40 °C 75% RH open storage conditions for 6 months with no physical evidence of crystallization or loss of dissolution performance. Though 034 was a chemical analogue with similar physical chemical properties to 452, a physically stable SDD of 034 could not be formulated in HPMCAS-M at any of the drug loads attempted. This study was used to develop experience with specific physical characterization laboratory techniques to evaluate the physical stability of SDDs and to characterize the propensity of SDDs to phase separate and possibly crystallize. The screening strategy adopted was to stress the formulated SDDs with a temperature humidity screen, within the calorimeter, and to apply orthogonal analytical techniques to gain a more informed understanding of why these SDDs formulated with HPMCAS-M demonstrated such different physical stability. Isothermal calorimetry (thermal activity monitor, TAM) was employed as a primary stress screen wherein the SDD formulations were monitored for 3 days at 37 °C 100% RH for signs of phase separation and possible crystallization of API. Powder X-ray diffraction (pXRD), modulated differential scanning calorimetry (mDSC), Fourier transform infrared spectroscopy (FTIR), and solid state nuclear magnetic resonance (ssNMR) were all used to examine formulated SDDs and neat amorphous drug. 452 SDDs formulated at 30% (wt/wt %) or less did not show phase separation behavior upon

  13. Children in divorce: intervention in the phase of separation.

    PubMed

    Derdeyn, A P

    1977-07-01

    Divorce of their parents can create difficulties for the development of young children. The ability of children to integrate the various losses involved in the breaking up of a family is impeded by limitations of their cognitive understanding of events taking place during the separation phase. Because their thinking process is as yet immature, children often feel responsible for the divorce, and they otherwise distort the meaning of the events about them. The pediatrician can often guide and encourage parents to facilitate their children's understanding and acceptance of the changes in their lives.

  14. Vortex motion phase separator for zero gravity liquid transfer

    NASA Technical Reports Server (NTRS)

    Howard, Frank S. (Inventor); Fraser, Wilson M., Jr. (Inventor)

    1989-01-01

    A vortex motion phase separator is disclosed for transferring a liquid in a zero gravity environment while at the same time separating the liquid from vapors found within either the sender or the receiving tanks. The separator comprises a rigid sender tank having a circular cross-section and rigid receiver tank having a circular cross-section. A plurality of ducts connects the sender tank and the receiver tank. Disposed within the ducts connecting the receiver tank and the sender tank is a pump and a plurality of valves. The pump is powered by an electric motor and is adapted to draw either the liquid or a mixture of the liquid and the vapor from the sender tank. Initially, the mixture drawn from the sender tank is directed through a portion of the ductwork and back into the sender tank at a tangent to the inside surface of the sender tank, thereby creating a swirling vortex of the mixture within the sender tank. As the pumping action increases, the speed of the swirling action within the sender tank increases creating an increase in the centrifugal force operating on the mixture. The effect of the centrifugal force is to cause the heavier liquid to migrate to the inside surface of the sender tank and to separate from the vapor. When this separation reaches a predetermined degree, control means is activated to direct the liquid conveyed by the pump directly into the receiver tank. At the same time, the vapor within the receiver tank is directed from the receiver tank back into the sender tank. This flow continues until substantially all of the liquid is transferred from the sender tank to the receiver tank.

  15. Bose-Einstein condensation in a frustrated triangular optical lattice

    NASA Astrophysics Data System (ADS)

    Janzen, Peter; Huang, Wen-Min; Mathey, L.

    2016-12-01

    The recent experimental condensation of ultracold atoms in a triangular optical lattice with a negative effective tunneling parameter paves the way for the study of frustrated systems in a controlled environment. Here, we explore the critical behavior of the chiral phase transition in such a frustrated lattice in three dimensions. We represent the low-energy action of the lattice system as a two-component Bose gas corresponding to the two minima of the dispersion. The contact repulsion between the bosons separates into intra- and intercomponent interactions, referred to as V0 and V12, respectively. We first employ a Huang-Yang-Luttinger approximation of the free energy. For V12/V0=2 , which corresponds to the bare interaction, this approach suggests a first-order phase transition, at which both the U (1 ) symmetry of condensation and the Z2 symmetry of the emergent chiral order are broken simultaneously. Furthermore, we perform a renormalization-group calculation at one-loop order. We demonstrate that the coupling regime 0 1 we show that V0 flows to a negative value, while V12 increases and remains positive. This results in a breakdown of the effective quartic-field theory due to a cubic anisotropy and, again, suggests a discontinuous phase transition.

  16. Digital holographic microscopy of phase separation in multicomponent lipid membranes

    NASA Astrophysics Data System (ADS)

    Farzam Rad, Vahideh; Moradi, Ali-Reza; Darudi, Ahmad; Tayebi, Lobat

    2016-12-01

    Lateral in-homogeneities in lipid compositions cause microdomains formation and change in the physical properties of biological membranes. With the presence of cholesterol and mixed species of lipids, phospholipid membranes segregate into lateral domains of liquid-ordered and liquid-disordered phases. Coupling of two-dimensional intralayer phase separations and interlayer liquid-crystalline ordering in multicomponent membranes has been previously demonstrated. By the use of digital holographic microscopy (DHMicroscopy), we quantitatively analyzed the volumetric dynamical behavior of such membranes. The specimens are lipid mixtures composed of sphingomyelin, cholesterol, and unsaturated phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine. DHMicroscopy in a transmission mode is an effective tool for quantitative visualization of phase objects. By deriving the associated phase changes, three-dimensional information on the morphology variation of lipid stacks at arbitrary time scales is obtained. Moreover, the thickness distribution of the object at demanded axial planes can be obtained by numerical focusing. Our results show that the volume evolution of lipid domains follows approximately the same universal growth law of previously reported area evolution. However, the thickness of the domains does not alter significantly by time; therefore, the volume evolution is mostly attributed to the changes in area dynamics. These results might be useful in the field of membrane-based functional materials.

  17. Modeling reaction fronts of separated condensed phase reactants

    NASA Astrophysics Data System (ADS)

    Koundinyan, Sushilkumar; Stewart, D. Scott; Matalon, Moshe

    2017-01-01

    We present a Gibbs free energy approach to modeling reaction fronts in condensed phase reactive materials. The current interest is in chemical reactions of condensed phase reactants that are initially separated. In energetic materials such reactions are observed to occur extremely fast and at relatively sharp fronts. The condensed phase combustion process differs in several aspects from classical gaseous combustion due to the disparity between the characteristic thermal conductivity length and the mass diffusion lengths and a volume, temperature, stress, mass fraction equation of state that principally depends only on the component reference volumes and the current mixture composition. To retain a simple planar configuration, we consider the two reactants, in solid phase, are in motion towards each other characterized by counter-flow geometry. We apply the model to a simplified Titanium-Boron system and present the analysis of reaction zone length for various strain rates. The numerical results are validated with asymptotic approximations at the Burke-Schumann (complete combustion) limit.

  18. Phase Separation in Lean Grade Duplex Stainless Steel 2101

    SciTech Connect

    Garfinkel, D.; Poplawsky, Jonathan D.; Guo, Wei; Young, Jr., George A.; Tucker, Julie

    2015-08-19

    The use of duplex stainless steels (DSS) in nuclear power generation systems is limited by thermal instability that leads to embrittlement in the temperature range of 204°C - 538°C. New lean grade alloys, such as 2101, offer the potential to mitigate these effects. Thermal embrittlement was quantified through impact toughness and hardness testing on samples of alloy 2101 after aging at 427°C for various durations (1-10,000 hours). Additionally, atom probe tomography (APT) was utilized in order to observe the kinetics of α-α’ separation and G-phase formation. Mechanical testing and APT data for two other DSS alloys, 2003 and 2205 were used as a reference to 2101. The results show that alloy 2101 exhibits superior performance compared to the standard grade DSS alloy, 2205, but inferior to the lean grade alloy, 2003, in mechanical testing. APT data demonstrates that the degree of α-α’ separation found in alloy 2101 closely resembles that of 2205, and greatly exceeds 2003. Additionally, contrary to what was observed in 2003, 2101 demonstrated G-phase like precipitates after long aging times, though precipitates were not as abundant as was observed in 2205.

  19. Dynamic phase separation: from coarsening to turbulence via structure formation.

    PubMed

    Golovin, A A; Pismen, L M

    2004-09-01

    We investigate some new two-dimensional evolution models belonging to the class of convective Cahn-Hilliard models: (i) a local model with a scalar order parameter, (ii) a nonlocal model with a scalar order parameter, and (iii) a model with a vector order parameter. These models are applicable to phase-separating system where concentration gradients cause hydrodynamic motion due to buoyancy or Marangoni effect. The numerical study of the models shows transition from coarsening, typical of Cahn-Hilliard systems, to spatiotemporally irregular behavior (turbulence), typical of the Kuramoto-Sivashinsky equation, which is obtained in the limit of very strong driving. The transition occurs not in a straightforward way, but through the formation of spatial patterns that emerge for intermediate values of the driving intensity. As in driven one-dimensional models studied before, the mere presence of the driving force, however small, breaks the symmetry between the two separating phases, as well as increases the coarsening rate. With increasing driving, coarsening stops. The dynamics is generally irregular at strong driving, but exhibits specific structural features.

  20. The mechanical properties of phase separated protein droplets

    NASA Astrophysics Data System (ADS)

    Jawerth, Louise; Ijavi, Mahdiye; Patel, Avinash; Saha, Shambaditya; Jülicher, Frank; Hyman, Anthony

    In vivo, numerous proteins associate into liquid compartments by de-mixing from the surrounding solution, similar to oil molecules in water. Many of these proteins and their corresponding liquid compartments play a crucial role in important biological processes, for instance germ line specification in C. elegans or in neurodegenerative diseases such as Amyotrophic lateral sclerosis (ALS). However, despite their importance, very little is known about the physical properties of the resulting droplets as well as the physical mechanisms that control their phase separation from solution. To gain a deeper understanding of these aspects, we study a few such proteins in vitro. When these proteins are purified and added to a physiological buffer, they phase separate into droplets ranging in size from a few to tens of microns with liquid-like behavior similar to their physiological counterparts. By attaching small beads to the surface of the droplets, we can deform the droplets by manipulating the beads directly using optical tweezers. By measuring the force required to deform the droplets we determine their surface tension, elasticity and viscosity as well as the frequency response of these properties. We also measure these properties using passive micro-rheology.

  1. Correlated lateral phase separations in stacks of lipid membranes

    SciTech Connect

    Hoshino, Takuma; Komura, Shigeyuki; Andelman, David

    2015-12-28

    Motivated by the experimental study of Tayebi et al. [Nat. Mater. 11, 1074 (2012)] on phase separation of stacked multi-component lipid bilayers, we propose a model composed of stacked two-dimensional Ising spins. We study both its static and dynamical features using Monte Carlo simulations with Kawasaki spin exchange dynamics that conserves the order parameter. We show that at thermodynamical equilibrium, due to strong inter-layer correlations, the system forms a continuous columnar structure for any finite interaction across adjacent layers. Furthermore, the phase separation shows a faster dynamics as the inter-layer interaction is increased. This temporal behavior is mainly due to an effective deeper temperature quench because of the larger value of the critical temperature, T{sub c}, for larger inter-layer interaction. When the temperature ratio, T/T{sub c}, is kept fixed, the temporal growth exponent does not increase and even slightly decreases as a function of the increased inter-layer interaction.

  2. Phase Separation in Lean Grade Duplex Stainless Steel 2101

    DOE PAGES

    Garfinkel, D.; Poplawsky, Jonathan D.; Guo, Wei; ...

    2015-08-19

    The use of duplex stainless steels (DSS) in nuclear power generation systems is limited by thermal instability that leads to embrittlement in the temperature range of 204°C - 538°C. New lean grade alloys, such as 2101, offer the potential to mitigate these effects. Thermal embrittlement was quantified through impact toughness and hardness testing on samples of alloy 2101 after aging at 427°C for various durations (1-10,000 hours). Additionally, atom probe tomography (APT) was utilized in order to observe the kinetics of α-α’ separation and G-phase formation. Mechanical testing and APT data for two other DSS alloys, 2003 and 2205 weremore » used as a reference to 2101. The results show that alloy 2101 exhibits superior performance compared to the standard grade DSS alloy, 2205, but inferior to the lean grade alloy, 2003, in mechanical testing. APT data demonstrates that the degree of α-α’ separation found in alloy 2101 closely resembles that of 2205, and greatly exceeds 2003. Additionally, contrary to what was observed in 2003, 2101 demonstrated G-phase like precipitates after long aging times, though precipitates were not as abundant as was observed in 2205.« less

  3. Liquid-Liquid Phase Separation of Oil Bodies from Seeds.

    PubMed

    Nykiforuk, Cory L

    2016-01-01

    Fundamentally, oil bodies are discrete storage organelles found in oilseeds, comprising a hydrophobic triacylglycerol core surrounded by a half-unit phospholipid membrane and an outer shell of specialized proteins known as oleosins. Oil bodies possess a number of attributes that were exploited by SemBioSys Genetics to isolate highly enriched fractions of oil bodies through liquid-liquid phase separation for a number of commercial applications. The current chapter provides a general guide for the isolation of oil bodies from Arabidopsis and/or safflower seed, from which protocols can be refined for different oilseed sources. For SemBioSys Genetic's recombinant technology, therapeutic proteins were covalently attached to oleosins or fused in-frame with ligands which bound oil bodies, facilitating their recovery to high levels of purity during "upstream processing" of transformed seed. Core to this technology was oil body isolation consisting of simple manipulation including homogenization of seeds to free the oil bodies, followed by the removal of insoluble fractions, and phase separation to recover the oil bodies. During oil body enrichment (an increase in oil body content concomitant with removal of impurities), a number of options and tips are provided to aid researchers in the manipulation and monitoring of these robust organelles.

  4. Shrink, twist, ripple and melt: Studies of frustrated liquid crystals

    NASA Astrophysics Data System (ADS)

    Fernsler, Jonathan G.

    Complex structures can arise out of a simple system with more than one competing influence on its behavior. The protypical example of this is the two-dimensional triangular lattice Ising model. The ferromagnetic model has two simple degenerate ground states of all spins up or down, but the antiferromagnetic model is a frustrated system. Its geometry does not allow satisfaction of the antiferro condition everywhere, which produces complex ordered structures with dimerization of the spins [1]. Without frustration, the complex structures and phase behavior are lost. All of the topics discussed in this thesis concern smectic liquid crystals. Liquid crystals are perhaps uniquely adept at manifesting frustrated phases. Their combination of periodicity in one or more dimensions allows ordered structures, yet their fluid nature in remaining dimensions allows creation of defects and extraordinarily complex structures in ways that a normal crystal could not tolerate. Liquid crystals contain a huge menagerie of frustrated phases and effects including the polarization modulated [2], vortex lattice [3], twist grain boundary [4], and blue [5] phases, as well as frustrated structures such as cholesteric or SmC* helix unwinding [6], defect lattices in thin films [7], and bend melted grain boundary defects [8], arising from boundary conditions and field effects. In this thesis, we study four liquid crystal systems that show unusual phase behavior or complex structures, deriving from the effects of frustration. Frustration, despite some human prejudices against the word, leaves nature all the more interesting and beautiful.

  5. Emergent geometric frustration of artificial magnetic skyrmion crystals

    SciTech Connect

    Ma, Fusheng; Reichhardt, Charles; Gan, Weiliang; Reichhardt, Cynthia Jane Olson; Lew, Wen Siang

    2016-10-05

    Magnetic skyrmions have been receiving growing attention as potential information storage and magnetic logic devices since an increasing number of materials have been identified that support skyrmion phases. Explorations of artificial frustrated systems have led to new insights into controlling and engineering new emergent frustration phenomena in frustrated and disordered systems. Here, we propose a skyrmion spin ice, giving a unifying framework for the study of geometric frustration of skyrmion crystals (SCs) in a nonfrustrated artificial geometrical lattice as a consequence of the structural confinement of skyrmions in magnetic potential wells. The emergent ice rules from the geometrically frustrated SCs highlight a novel phenomenon in this skyrmion system: emergent geometrical frustration. We demonstrate how SC topology transitions between a nonfrustrated periodic configuration and a frustrated icelike ordering can also be realized reversibly. The proposed artificial frustrated skyrmion systems can be annealed into different ice phases with an applied current-induced spin-transfer torque, including a long-range ordered ice rule obeying ground state, as-relaxed random state, biased state, and monopole state. In conclusion, the spin-torque reconfigurability of the artificial skyrmion ice states, difficult to achieve in other artificial spin ice systems, is compatible with standard spintronic device fabrication technology, which makes the semiconductor industrial integration straightforward.

  6. Emergent geometric frustration of artificial magnetic skyrmion crystals

    NASA Astrophysics Data System (ADS)

    Ma, Fusheng; Reichhardt, C.; Gan, Weiliang; Reichhardt, C. J. Olson; Lew, Wen Siang

    2016-10-01

    Magnetic skyrmions have been receiving growing attention as potential information storage and magnetic logic devices since an increasing number of materials have been identified that support skyrmion phases. Explorations of artificial frustrated systems have led to new insights into controlling and engineering new emergent frustration phenomena in frustrated and disordered systems. Here, we propose a skyrmion spin ice, giving a unifying framework for the study of geometric frustration of skyrmion crystals (SCs) in a nonfrustrated artificial geometrical lattice as a consequence of the structural confinement of skyrmions in magnetic potential wells. The emergent ice rules from the geometrically frustrated SCs highlight a novel phenomenon in this skyrmion system: emergent geometrical frustration. We demonstrate how SC topology transitions between a nonfrustrated periodic configuration and a frustrated icelike ordering can also be realized reversibly. The proposed artificial frustrated skyrmion systems can be annealed into different ice phases with an applied current-induced spin-transfer torque, including a long-range ordered ice rule obeying ground state, as-relaxed random state, biased state, and monopole state. The spin-torque reconfigurability of the artificial skyrmion ice states, difficult to achieve in other artificial spin ice systems, is compatible with standard spintronic device fabrication technology, which makes the semiconductor industrial integration straightforward.

  7. Emergent geometric frustration of artificial magnetic skyrmion crystals

    DOE PAGES

    Ma, Fusheng; Reichhardt, Charles; Gan, Weiliang; ...

    2016-10-05

    Magnetic skyrmions have been receiving growing attention as potential information storage and magnetic logic devices since an increasing number of materials have been identified that support skyrmion phases. Explorations of artificial frustrated systems have led to new insights into controlling and engineering new emergent frustration phenomena in frustrated and disordered systems. Here, we propose a skyrmion spin ice, giving a unifying framework for the study of geometric frustration of skyrmion crystals (SCs) in a nonfrustrated artificial geometrical lattice as a consequence of the structural confinement of skyrmions in magnetic potential wells. The emergent ice rules from the geometrically frustrated SCsmore » highlight a novel phenomenon in this skyrmion system: emergent geometrical frustration. We demonstrate how SC topology transitions between a nonfrustrated periodic configuration and a frustrated icelike ordering can also be realized reversibly. The proposed artificial frustrated skyrmion systems can be annealed into different ice phases with an applied current-induced spin-transfer torque, including a long-range ordered ice rule obeying ground state, as-relaxed random state, biased state, and monopole state. In conclusion, the spin-torque reconfigurability of the artificial skyrmion ice states, difficult to achieve in other artificial spin ice systems, is compatible with standard spintronic device fabrication technology, which makes the semiconductor industrial integration straightforward.« less

  8. Frustration by design

    DOE PAGES

    Gilbert, Ian; Nisoli, Cristiano; Schiffer, Peter

    2016-07-01

    Geometrical frustration is a condition that occurs when a material’s lattice geometry precludes minimizing the energy of all the interactions among pairs of neighbors simultaneously. Moreover, the simplest example is three antiferromagnetically coupled Ising spins, pointing up or down, on the corners of an equilateral triangle: It is also impossible to arrange the spins so that each pair is antiparallel. In more complex magnetic lattices, the frustrated state can arise from the combination of lattice geometry and the strength and sign of the interactions among the magnetic dipole moments.1 (See the article by Roderich Moessner and Art Ramirez, Physics Today,more » February 2006, page 24.) A wide variety of exotic and collective phenomena sometimes arises from the competing interactions. One prime example is spin liquids, materials in which the local atomic moments fluctuate down to the lowest accessible temperatures and never settle into a static ground-state configuration.« less

  9. Frustration by design

    SciTech Connect

    Gilbert, Ian; Nisoli, Cristiano; Schiffer, Peter

    2016-07-01

    Geometrical frustration is a condition that occurs when a material’s lattice geometry precludes minimizing the energy of all the interactions among pairs of neighbors simultaneously. Moreover, the simplest example is three antiferromagnetically coupled Ising spins, pointing up or down, on the corners of an equilateral triangle: It is also impossible to arrange the spins so that each pair is antiparallel. In more complex magnetic lattices, the frustrated state can arise from the combination of lattice geometry and the strength and sign of the interactions among the magnetic dipole moments.1 (See the article by Roderich Moessner and Art Ramirez, Physics Today, February 2006, page 24.) A wide variety of exotic and collective phenomena sometimes arises from the competing interactions. One prime example is spin liquids, materials in which the local atomic moments fluctuate down to the lowest accessible temperatures and never settle into a static ground-state configuration.

  10. Modeling reaction fronts of separated condensed phase reactants

    NASA Astrophysics Data System (ADS)

    Koundinyan, Sushilkumar; Matalon, Moshe; Stewart, D. Scott; Bdzil, John

    2015-06-01

    We present a Gibbs free energy approach to modeling reaction fronts in condensed phase reactive materials. The current interest is in chemical reactions of condensed phase reactants that are initially separated. In energetic materials such reactions are observed to occur extremely fast and at relatively sharp fronts. The solid-to-solid combustion process differs in several aspects from classical gaseous combustion due to the disparity between the characteristic thermal conductivity length and the mass diffusion lengths and a volume, temperature, stress, mass fraction equation of state that principally depends only on the component reference volumes and the current mixture composition. To retain a simple planar configuration, we consider the two reactants, in solid phase, are in motion towards each other characterized by counter-flow geometry. We apply the model to a simplified Titanium-Boron system and present the analysis of reaction zone length for various strain rates. The numerical results are validated with asymptotic approximations at the Burke-Schumann limit. Supported by HDTRA1-10-1-0020 (DTRA), AF Sub MO C00039417-1 (AFOSR/TRE).

  11. Dual Phase Membrane for High Temperature CO2 Separation

    SciTech Connect

    Jerry Lin

    2007-06-30

    This project aimed at synthesis of a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Metal-carbonate dual-phase membranes were prepared by the direct infiltration method and the synthesis conditions were optimized. Permeation tests for CO{sub 2} and N{sub 2} from 450-750 C showed very low permeances of those two gases through the dual-phase membrane, which was expected due to the lack of ionization of those two particular gases. Permeance of the CO{sub 2} and O{sub 2} mixture was much higher, indicating that the gases do form an ionic species, CO{sub 3}{sup 2-}, enhancing transport through the membrane. However, at temperatures in excess of 650 C, the permeance of CO{sub 3}{sup 2-} decreased rapidly, while predictions showed that permeance should have continued to increase with temperature. XRD data obtained from used membrane indicated that lithium iron oxides formed on the support surface. This lithium iron oxide layer has a very low conductivity, which drastically reduces the flow of electrons to the CO{sub 2}/O{sub 2} gas mixture; thus limiting the formation of the ionic species required for transport through the membrane. These results indicated that the use of stainless steel supports in a high temperature oxidative environment can lead to decreased performance of the membranes. This revelation created the need for an oxidation resistant support, which could be gained by the use of a ceramic-type membrane. Work was extended to synthesize a new inorganic dual-phase carbonate membrane for high temperature CO{sub 2} separation. Helium permeance of the support before and after infiltration of molten carbonate are on the order of 10{sup -6} and 10{sup -10} moles/m{sup 2} {center_dot} Pa {center_dot} s respectively, indicating that the molten carbonate is able to sufficiently infiltrate the membrane. It was found that La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (LSCF) was a suitable candidate for the support

  12. Weak randomness in geometrically frustrated systems: spin-glasses

    NASA Astrophysics Data System (ADS)

    Schmidt, M.; Zimmer, F. M.; Magalhaes, S. G.

    2015-02-01

    We study the competition between the spin-glass (SG) phase and antiferromagnetic (AF), superantiferromagnetic or ferromagnetic (FE) order in geometrically frustrated systems. We consider a model with two types of frustration: one coming from disordered interactions (J) and another coming from the square-lattice Ising spin system with first-(J1) and second-(J2) neighbor interactions (intrinsic frustration). The disordered interactions are between clusters and they follow the van Hemmen model, which represents a limit of weak frustration. The cluster mean-field approximation is used to treat the short-range intercluster interactions. Results are exhibited in phase diagrams of the temperature T versus J for several values of {{J}2}/{{J}1}. When the intrinsic frustration increases, the Néel and Curie temperatures decrease at the same time so that the SG phase appears at a lower J. Moreover, the FE correlations enhance the SG behavior, while AF correlations reduce the SG region at the same level of intrinsic frustration. These results indicate that a weak disorder in geometrically frustrated systems is able to stabilize the SG phase.

  13. Tobacco protein separation by aqueous two-phase extraction.

    PubMed

    Balasubramaniam, Deepa; Wilkinson, Carol; Van Cott, Kevin; Zhang, Chenming

    2003-03-07

    Tobacco has long been considered as a host to produce large quantity of high-valued recombinant proteins. However, dealing with large quantities of biomass is a challenge for downstream processing. Aqueous two-phase extraction (ATPE) has been widely used in purifying proteins from various sources. It is a protein-friendly process and can be scaled up easily. In this paper, ATPE was studied for its applicability to recombinant protein purification from tobacco with egg white lysozyme as the model protein. Separate experiments with poly(ethylene glycol) (PEG)-salt-tobacco extract and PEG-salt-lysozyme were carried out to determine the partition behavior of tobacco protein and lysozyme, respectively. Two-level fractional factorial designs were used to study the effects of factors such as, PEG molecular mass, PEG concentration, the concentration of phase forming salt, sodium chloride concentration and pH, on protein partitioning. The results showed that, among the studied systems, PEG-sodium sulfate system was most suitable for lysozyme purification. Detailed experiments were conducted by spiking lysozyme into the tobacco extract. The conditions with highest selectivity of lysozyme over native tobacco protein were determined using a response surface design. The purification factor was further improved by decreasing the phase ratio along the tie line corresponding to the phase compositions with the highest selectivity. Under selected conditions the lysozyme yield was predicted to be 87% with a purification factor of 4 and concentration factor of 14. From this study, ATPE was shown to be suitable for initial protein recovery and partial purification from transgenic tobacco.

  14. Model system studies with a phase separated membrane bioreactor

    NASA Technical Reports Server (NTRS)

    Petersen, G. R.; Seshan, P. K.; Dunlop, Eric H.

    1989-01-01

    The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestial simulation.

  15. Phase separated membrane bioreactor - Results from model system studies

    NASA Technical Reports Server (NTRS)

    Petersen, G. R.; Seshan, P. K.; Dunlop, E. H.

    1989-01-01

    The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestrial simulation.

  16. The evolutionary significance of phase-separated microsystems

    NASA Technical Reports Server (NTRS)

    Fox, S. W.

    1976-01-01

    The source, preparation, and properties of phase-separated systems such as lipid layers, coacervate droplets, sulphobes, and proteinoid microspheres are reviewed. These microsystems are of interest as partial models for the cell and as partial or total models for the protocell. Conceptual benefits from the study of such models include clues to experiments on origins, insights into principles of action, and, in some instances, presumable models of the origin of the protocell. The benefits to evolution of organized chemical units are many, and can in part be analyzed. Ease of formation suggests that such units would have arisen early in primordial organic evolution. Integration of these various concepts and the results of consequent experiments have contributed to the developing theory of the origins of primordial and contemporary life.

  17. Chronotaxic systems with separable amplitude and phase dynamics

    NASA Astrophysics Data System (ADS)

    Suprunenko, Yevhen F.; Clemson, Philip T.; Stefanovska, Aneta

    2014-01-01

    Until recently, deterministic nonautonomous oscillatory systems with stable amplitudes and time-varying frequencies were not recognized as such and have often been mistreated as stochastic. These systems, named chronotaxic, were introduced in Phys. Rev. Lett. 111, 024101 (2013), 10.1103/PhysRevLett.111.024101. In contrast to conventional limit cycle models of self-sustained oscillators, these systems posses a time-dependent point attractor or steady state. This allows oscillations with time-varying frequencies to resist perturbations, a phenomenon which is ubiquitous in living systems. In this work a detailed theory of chronotaxic systems is presented, specifically in the case of separable amplitude and phase dynamics. The theory is extended by the introduction of chronotaxic amplitude dynamics. The wide applicability of chronotaxic systems to a range of fields from biological and condensed matter systems to robotics and control theory is discussed.

  18. Phase separated membrane bioreactor: results from model system studies.

    PubMed

    Petersen, G R; Seshan, P K; Dunlop, E H

    1989-01-01

    The operation and evaluation of a bioreactor designed for high intensity oxygen transfer in a microgravity environment is described. The reactor itself consists of a zero headspace liquid phase separated from the air supply by a long length of silicone rubber tubing through which the oxygen diffuses in and the carbon dioxide diffuses out. Mass transfer studies show that the oxygen is film diffusion controlled both externally and internally to the tubing and not by diffusion across the tube walls. Methods of upgrading the design to eliminate these resistances are proposed. Cell growth was obtained in the fermenter using Saccharomyces cerevisiae showing that this concept is capable of sustaining cell growth in the terrestrial [correction of terrestial] simulation.

  19. Electronic phase separation transition as the origin of the superconductivity and pseudogap phase of cuprates

    NASA Astrophysics Data System (ADS)

    de Mello, E. V. L.; Kasal, R. B.; Passos, C. A. C.

    2009-06-01

    To deal with the physics of cuprate superconductivity we propose an electronic phase separation transition that segregates the holes into high and low density domains. The calculated grain boundary potential favors the development of intragrain superconducting amplitudes. The zero resistivity transition arises only when the intergrain Josephson coupling EJ is of the order of the thermal energy and phase locking takes place among the superconducting grains. We show that this approach explains the pseudogap and superconducting phases and it also reproduces some recent scanning tunneling microscopy data.

  20. Electronic phase separation transition as the origin of the superconductivity and pseudogap phase of cuprates.

    PubMed

    de Mello, E V L; Kasal, R B; Passos, C A C

    2009-06-10

    To deal with the physics of cuprate superconductivity we propose an electronic phase separation transition that segregates the holes into high and low density domains. The calculated grain boundary potential favors the development of intragrain superconducting amplitudes. The zero resistivity transition arises only when the intergrain Josephson coupling E(J) is of the order of the thermal energy and phase locking takes place among the superconducting grains. We show that this approach explains the pseudogap and superconducting phases and it also reproduces some recent scanning tunneling microscopy data.

  1. Evolution of a phase separated gravity independent bioreactor

    NASA Astrophysics Data System (ADS)

    Villeneuve, Peter E.; Dunlop, Eric H.

    The evolution of a phase-separated gravity-independent bioreactor is described. The initial prototype, a zero head-space manifold silicone membrane based reactor, maintained large diffusional resistances. Obtaining oxygen transfer rates needed to support carbon-recycling aerobic microbes is impossible if large resistances are maintained. Next generation designs (Mark I and II) mimic heat exchanger design to promote turbulence at the tubing-liquid interface, thereby reducing liquid and gas side diffusional resistances. While oxygen transfer rates increased by a factor of ten, liquid channeling prevented further increases. To overcome these problems, a Mark III reactor was developed which maintains inverted phases, i.e., media flows inside the silicone tubing, oxygen gas is applied external to the tubing. This enhances design through changes in gas side driving force concentration and liquid side turbulence levels. Combining an applied external pressure of four atmospheres with increased Reynolds numbers resulted in oxygen transfer intensities of 232 mmol O2/l/h (1000 times greater than first prototype and comparable to a conventional fermenter). A 1.0 liter Mark III reactor can potentially deliver oxygen supplies necessary to support cell cultures needed to recycle a 10 astronaut carbon load continuously.

  2. Evolution of a phase separated gravity independent bioreactor

    NASA Technical Reports Server (NTRS)

    Villeneuve, Peter E.; Dunlop, Eric H.

    1992-01-01

    The evolution of a phase-separated gravity-independent bioreactor is described. The initial prototype, a zero head-space manifold silicone membrane based reactor, maintained large diffusional resistances. Obtaining oxygen transfer rates needed to support carbon-recycling aerobic microbes is impossible if large resistances are maintained. Next generation designs (Mark I and II) mimic heat exchanger design to promote turbulence at the tubing-liquid interface, thereby reducing liquid and gas side diffusional resistances. While oxygen transfer rates increased by a factor of ten, liquid channeling prevented further increases. To overcome these problems, a Mark III reactor was developed which maintains inverted phases, i.e., media flows inside the silicone tubing, oxygen gas is applied external to the tubing. This enhances design through changes in gas side driving force concentration and liquid side turbulence levels. Combining an applied external pressure of 4 atm with increased Reynolds numbers resulted in oxygen transfer intensities of 232 mmol O2/l per hr (1000 times greater than the first prototype and comparable to a conventional fermenter). A 1.0 liter Mark III reactor can potentially deliver oxygen supplies necessary to support cell cultures needed to recycle a 10-astronaut carbon load continuously.

  3. Phase separation in a polarized Fermi gas with spin-orbit coupling

    SciTech Connect

    Yi, W.; Guo, G.-C.

    2011-09-15

    We study the phase separation of a spin-polarized Fermi gas with spin-orbit coupling near a wide Feshbach resonance. As a result of the competition between spin-orbit coupling and population imbalance, the phase diagram for a uniform gas develops a rich structure of phase separation involving topologically nontrivial gapless superfluid states. We then demonstrate the phase separation induced by an external trapping potential and discuss the optimal parameter region for the experimental observation of the gapless superfluid phases.

  4. DUAL PHASE MEMBRANE FOR HIGH TEMPERATURE CO2 SEPARATION

    SciTech Connect

    Jerry Y.S. Lin; Seungjoon Chung; Matthew Anderson

    2005-12-01

    This project is intended to expand upon the previous year's research en route to the development of a sustainable dual phase membrane for CO{sub 2} separation. It was found that the pores within the supports had to be less than 9 {micro}m in order to maintain the stability of the dual phase membrane. Pores larger than 9 {micro}m would be unable to hold the molten carbonate phase in place, rendering the membrane ineffective. Calculations show that 80% of the pore volume of the 0.5 media grade metal support was filled with the molten carbonate. Information obtained from EDS and SEM confirmed that the molten carbonate completely infiltrated the pores on both the contact and non-contact size of the metal support. Permeation tests for CO{sub 2} and N{sub 2} at 450-750 C show very low permeance of those two gases through the dual phase membrane, which was expected due to the lack of ionization of those two gases. Permeance of the CO{sub 2} and O{sub 2} mixture was much higher, indicating that the gases do form an ionic species, CO{sub 3}{sup 2-}, enhancing transport through the membrane. However, at temperatures in excess of 650 C, the permeance of CO{sub 3}{sup 2-} decreased quite rapidly, while predictions showed that permeance should have continued to increase. XRD data obtained form the surface of the membrane indicated the formation of lithium iron oxides on the support. This layer has a very low conductivity, which drastically reduces the flow of electrons to the CO{sub 2}/O{sub 2} gas mixture, limiting the formation of the ionic species. These results indicate that the use of stainless steel supports in a high temperature oxidative environment can lead to decreased performance of the membranes. This revelation has created the need for an oxidation resistant support, which can be gained by the use of a ceramic-type membrane. Future research efforts will be directed towards preparation of a new ceramic-carbonate dual phase membrane. The membrane will based on an

  5. Ferromagnetic order in silicon-manganese alloys with phase separation

    SciTech Connect

    Men'shov, V. N. Tugushev, V. V.

    2011-07-15

    A phenomenological model of high-temperature ferromagnetism in silicon-manganese alloys has been proposed taking into account phase separation in these alloys, where manganese-rich particles of the secondary phase (precipitate MnSi{sub 2-z} with z Almost-Equal-To 0.25-0.30) are formed inside a manganese-depleted matrix of almost pure silicon. Precipitate MnSi{sub 2-z} is considered as the silicide MnSi{sub 1.7} containing a certain number of magnetic defects whose origin is due to the presence of weakly hybridized 3d orbitals of manganese. The silicide MnSi{sub 1.7} is a weak band ferromagnet in which strong fluctuations of the spin density (paramagnons) are present at a temperature much higher than its Curie temperature. It has been shown that the ferromagnetic exchange interactions between the magnetic moments of defects in precipitate exists due to thermal excitations of the spin density and the ferromagnetic order can appear at a temperature much higher than the Curie temperature of the silicide. The spatial structures and characteristics of this order have been described in the framework of the proposed approach for both homogeneous bulk precipitate and precipitate particles of various shapes and sizes. The short-range magnetic order near the bulk phase transition has been analyzed taking into account inhomogeneities in the distribution of magnetic defects in precipitate. The experimental data on the magnetic properties of silicon-manganese alloys have been interpreted in terms of the theoretical results obtained in this work.

  6. Phase separation and doped-hole segregation in La{sub 2}CuO{sub 4+{delta}} and La{sub 2-x}Sr{sub x}CuO{sub 4+{delta}}

    SciTech Connect

    Johnston, D.C.; Bayless, W.R.; Borsa, F. |

    1994-05-01

    This paper reviews the magnetic, superconducting and structural phase diagrams of the title systems, with an emphasis on recent results from magnetic and structural neutron diffraction, magnetic susceptibility and {sup 139}La nuclear quadrupole resonance measurements. Results clarify the miscibility gap in the La{sub 2}CuO{sub 4+{delta}} system and indicate the occurrence of frustrated phase separation on a nanoscopic length scale in the La{sub 2{minus}x}Sr{sub x}CuO{sub 4} system with 0 < x {approx_lt} 0.05.

  7. Comparison of liquid and supercritical fluid chromatography mobile phases for enantioselective separations on polysaccharide stationary phases.

    PubMed

    Khater, Syame; Lozac'h, Marie-Anne; Adam, Isabelle; Francotte, Eric; West, Caroline

    2016-10-07

    Analysis and production of enantiomerically pure compounds is a major topic of interest when active pharmaceutical ingredients are concerned. Enantioselective chromatography has become a favourite both at the analytical and preparative scales. High-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC) are dominating the scene and are often seen as complementary techniques. Nowadays, for economic and ecologic reasons, SFC may be preferred over normal-phase HPLC (NPLC) as it allows significant reductions in solvent consumption. However, the transfer of NPLC methods to SFC is not always straightforward. In this study, we compare the retention of achiral molecules and separation of enantiomers under supercritical fluid (carbon dioxide with ethanol or isopropanol) and liquid normal-phase (heptane with ethanol or isopropanol) elution modes with polysaccharide stationary phases in order to explore the differences between the retention and enantioseparation properties between the two modes. Chemometric methods (namely quantitative structure-retention relationships and discriminant analysis) are employed to compare the results obtained on a large set of analytes (171 achiral probes and 97 racemates) and gain some understanding on the retention and separation mechanisms. The results indicate that, contrary to popular belief, carbon dioxide - solvent SFC mobile phases are often weaker eluents than liquid mobile phases. It appears that SFC and NPLC elution modes provide different retention mechanisms. While some enantioseparations are unaffected, facilitating the transfer between the two elution modes, other enantioseparations may be drastically different due to different types and strength of interactions contributing to enantioselectivity.

  8. Dual Phase Membrane for High Temperature CO2 Separation

    SciTech Connect

    Jerry Y.S. Lin; Matthew Anderson

    2006-09-29

    Dual-phase membranes consisting of stainless steel supports infiltrated with molten carbonate have been shown to be selective to CO{sub 2} at high temperatures (400-650 C). However, over time at high temperatures, the formation of iron oxides on the surface of the stainless steel supports render the membranes ineffective. This report details synthesis and characteristics of dual-phase carbonate membrane with an oxidation resistant perovskite type ceramic (lanthanum-strontium-cobaltite-iron; LSCF) support. Porous LSCF supports were prepared from its powder synthesized by the citrate method. Both steady state permeation and mercury porosimetry confirmed that the LSCF membrane sintered at 900 C has pores large enough to absorb molten carbonate, yet small enough to retain the molten carbonate under high pressure conditions. Results of XRD analysis have shown that LSCF and the molten carbonate mixture do not react with each other at temperatures below 700 C. Four-point method conductivity tests indicate that the support material has sufficiently high electronic conductivity for this application. Li-Na-K carbonate was coated to the porous LSCF support by a liquid infiltration method. Helium permeance of the support before and after infiltration of molten carbonate are on the order of 10{sup -6} and 10{sup -10} moles/m{sup 2} {center_dot} Pa {center_dot} s respectively, indicating that the molten carbonate is able to sufficiently infiltrate the membrane. Preliminary high temperature permeation experiments indicate that the membrane does separate CO{sub 2} in the presence of O{sub 2}, with a maximum flux of 0.623 ml/cm{sup 2} {center_dot} min obtained at 850 C.

  9. Relation between the phase separation and the crystallization in protein solutions

    NASA Astrophysics Data System (ADS)

    Tanaka, Shinpei; Yamamoto, Masahiko; Ito, Kohzo; Hayakawa, Reinosuke; Ataka, Mitsuo

    1997-07-01

    Liquid-liquid phase separation and crystallization (or solid-liquid phase separation) both occur in protein solutions. By adopting egg-white lysozyme for a model system, we compared two types of diagrams, a phase diagram of the liquid-liquid phase separation and a morphological diagram of protein crystals. By superimposing these diagrams, we distinguished two types of white precipitates, urchinlike spherulites arising from the crystallization and protein-rich droplets from the liquid-liquid phase separation. Furthermore, we observed a transformation from the protein-rich droplets to the spherulites, and simultaneously an unusual pattern evolution of the protein-rich phase unlike the conventional phase separation of typical binary mixtures. This is understood in terms of the competition between the crystallization and the liquid-liquid phase separation.

  10. Amorphous-Amorphous Phase Separation in API/Polymer Formulations.

    PubMed

    Luebbert, Christian; Huxoll, Fabian; Sadowski, Gabriele

    2017-02-15

    The long-term stability of pharmaceutical formulations of poorly-soluble drugs in polymers determines their bioavailability and therapeutic applicability. However, these formulations do not only often tend to crystallize during storage, but also tend to undergo unwanted amorphous-amorphous phase separations (APS). Whereas the crystallization behavior of APIs in polymers has been measured and modeled during the last years, the APS phenomenon is still poorly understood. In this study, the crystallization behavior, APS, and glass-transition temperatures formulations of ibuprofen and felodipine in polymeric PLGA excipients exhibiting different ratios of lactic acid and glycolic acid monomers in the PLGA chain were investigated by means of hot-stage microscopy and DSC. APS and recrystallization was observed in ibuprofen/PLGA formulations, while only recrystallization occurred in felodipine/PLGA formulations. Based on a successful modeling of the crystallization behavior using the Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT), the occurrence of APS was predicted in agreement with experimental findings.

  11. Nanoscale phase separation in ultra-tough hydrogels

    NASA Astrophysics Data System (ADS)

    Nixon, Ryan; Ten Hove, Jan Bart; Orozco, Adrian; Sawyer, W. Gregory; Angelini, Thomas

    2014-03-01

    Soft, wettable, water permeable materials that resist protein adsorption are essential to countless biomaterials, adaptive optics and microfluidics technologies. Hydrogels would be ideal for these applications, but are notoriously brittle and weak. For example, hydrogel coatings of synovial joint prosthetics exhibit irrecoverable damage after a single cycle of wear. The development of elastomer-like hydrogels that are tough, soft, and mechanically resilient would improve their versatility and create opportunities for a wide range of new applications. Here we present studies of an ultra-tough hydrogel, synthesized by the co-polymerization of two monomer species that polymerize at different rates and have strongly differing degrees of solvation. The resulting blended hydrogel network forms with both covalent and labile adhesive bonds, greatly improving recoverable energy dissipation and reducing fatigue relative to networks made from either constituent alone. We have studied the structural origins of the strengthening behavior using small angle x-ray scattering (SAXS) and found that the constituent polymers phase separate into nanoscale domains, which may prevent crack nucleation and propagation.

  12. Confinement-Driven Phase Separation of Quantum Liquid Mixtures

    NASA Astrophysics Data System (ADS)

    Prisk, T. R.; Pantalei, C.; Kaiser, H.; Sokol, P. E.

    2012-08-01

    We report small-angle neutron scattering studies of liquid helium mixtures confined in Mobil Crystalline Material-41 (MCM-41), a porous silica glass with narrow cylindrical nanopores (d=3.4nm). MCM-41 is an ideal model adsorbent for fundamental studies of gas sorption in porous media because its monodisperse pores are arranged in a 2D triangular lattice. The small-angle scattering consists of a series of diffraction peaks whose intensities are determined by how the imbibed liquid fills the pores. Pure He4 adsorbed in the pores show classic, layer-by-layer film growth as a function of pore filling, leaving the long range symmetry of the system intact. In contrast, the adsorption of He3-He4 mixtures produces a structure incommensurate with the pore lattice. Neither capillary condensation nor preferential adsorption of one helium isotope to the pore walls can provide the symmetry-breaking mechanism. The scattering is consistent with the formation of randomly distributed liquid-liquid microdomains ˜2.3nm in size, providing evidence that confinement in a nanometer scale capillary can drive local phase separation in quantum liquid mixtures.

  13. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Liang Hu

    2006-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer (transportation layer phase) is used for the increase of absorption rate. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the liquid mass transfer

  14. Dual Phase Membrane for High temperature CO2 Separation

    SciTech Connect

    Jerry Y.S. Lin; Matthew Anderson

    2005-12-01

    Research in the previous years in this project found that stainless steel supports are oxidized during high temperature, dual phase membrane separation of carbon dioxide (with oxygen). Consequently, a new material has been sought to alleviate the problems with oxidation. Lanthanum cobaltite oxide is a suitable candidate for the support material in the dual phase membrane due to its oxidation resistance and electronic conductivity. Porous lanthanum cobaltite membranes were prepared via the citrate method, using nitrate metal precursors as the source of La, Sr, Co and Fe. The material was prepared and ground into a powder, which was subsequently pressed into disks for sintering at 900 C. Conductivity measurements were evaluated using the four-probe DC method. Support pore size was determined by helium permeation. Conductivity of the lanthanum cobaltite material was found to be at a maximum of 0.1856 S/cm at 550 C. The helium permeance of the lanthanum cobaltite membranes for this research was on the order of 10{sup -6} moles/m{sup 2} {center_dot} Pa {center_dot} s, proving that the membranes are porous after sintering at 900 C. The average pore size based on steady state helium permeance measurements was found to be between 0.37 and 0.57 {micro}m. The lanthanum cobaltite membranes have shown to have desired porosity, pore size and electric conductivity as the support for the dual-phase membranes. Molten carbonate was infiltrated to the pores of lanthanum cobaltite membranes support. After infiltration with molten carbonate, the helium permeance of the membranes decreased by three orders of magnitude to 10{sup -9} moles/m{sup 2} {center_dot} Pa {center_dot} s. This number, however, is one order of magnitude larger than the room temperate permeance of the stainless steel supports after infiltration with molten carbonate. Optimization of the dip coating process with molten carbonate will be evaluated to determine if lower permeance values can be obtained with the

  15. Spin transport of the frustrated quasi-two-dimensional XY-like antiferromagnet

    NASA Astrophysics Data System (ADS)

    Lima, L. S.

    2017-01-01

    We use the Self Consistent Harmonic Approximation together with the Kubo formalism of the Linear Response Theory to study the spin transport in the two-dimensional frustrated Heisenberg antiferromagnet in a square lattice with easy-plane ion single anisotropy. The regular part of the spin conductivity σreg(ω) is determined for several values of the critical ion single parameter Dc, that separates the low D region from the large D quantum paramagnetic phase. We have obtained an abrupt change in the spin conductivity in the discontinuity points of the graphic Dc vs. η, where the system presents a quantum phase transition.

  16. Effect of OH content on phase separation behavior of soda-silica glasses

    NASA Technical Reports Server (NTRS)

    Neilson, G. F.; Weinberg, M. C.; Smith, G. L.

    1986-01-01

    The kinetics of phase separation in a gel and ordinary soda-silica glass are followed by use of small angle X-ray scattering. Also, the influence of OH on the phase separation behavior is studied. It is found that OH accelerates the growth of the secondary phase, and that gel and ordinary glasses of similar composition and OH concentration exhibit similar phase separation characteristics.

  17. Understanding the Impact of User Frustration Intensities on Task Performance Using the OCC Theory of Emotions

    NASA Technical Reports Server (NTRS)

    Washington, Gloria

    2012-01-01

    Have you heard the saying "frustration is written all over your falce"? Well this saying is true, but that is not the only place. Frustration is written all over your face and your body. The human body has various means to communicate an emotion without the utterance of a single word. The Media Equation says that people interact with computers as if they are human: this includes experiencing frustration. This research measures frustration by monitoring human body-based measures such as heart rate, posture, skin temperature. and respiration. The OCC Theory of Emotions is used to separate frustration into different levels or intensities. The results of this study showed that individual intensities of frustration exist, so that task performance is not degraded. Results from this study can be used by usability testers to model how much frustration is needed before task performance measures start to decrease.

  18. Carbon Dioxide Separation from Flue Gas by Phase Enhanced Absorption

    SciTech Connect

    Tim Fout

    2007-06-30

    A new process, phase enhanced absorption, was invented. The method is carried out in an absorber, where a liquid carrier (aqueous solution), an organic mixture (or organic compound), and a gas mixture containing a gas to be absorbed are introduced from an inlet. Since the organic mixture is immiscible or at least partially immiscible with the liquid carrier, the organic mixture forms a layer or small parcels between the liquid carrier and the gas mixture. The organic mixture in the absorber improves mass transfer efficiency of the system and increases the absorption rate of the gas. The organic mixture serves as a transportation media. The gas is finally accumulated in the liquid carrier as in a conventional gas-liquid absorption system. The presence of the organic layer does not hinder the regeneration of the liquid carrier or recovery of the gas because the organic layer is removed by a settler after the absorption process is completed. In another aspect, the system exhibited increased gas-liquid separation efficiency, thereby reducing the costs of operation and maintenance. Our study focused on the search of the organic layer or transportation layer to enhance the absorption rate of carbon dioxide. The following systems were studied, (1) CO{sub 2}-water system and CO{sub 2}-water-organic layer system; (2) CO{sub 2}-Potassium Carbonate aqueous solution system and CO{sub 2}-Potassium Carbonate aqueous solution-organic layer system. CO{sub 2}-water and CO{sub 2}-Potassium Carbonate systems are the traditional gas-liquid absorption processes. The CO{sub 2}-water-organic layer and CO{sub 2}-Potassium Carbonate-organic layer systems are the novel absorption processes, phase enhanced absorption. As we mentioned early, organic layer is used for the increase of absorption rate, and plays the role of transportation of CO{sub 2}. Our study showed that the absorption rate can be increased by adding the organic layer. However, the enhanced factor is highly depended on the

  19. Geometrically Frustrated Fracture Mechanics

    NASA Astrophysics Data System (ADS)

    Mitchell, Noah; Koning, Vinzenz; Vitelli, Vincenzo; Irvine, William T. M.

    2015-03-01

    When a flat elastic sheet is forced to conform to a surface with Gaussian curvature, stresses arise in the sheet. The mismatch between initial and final metrics gives rise to new fracture behavior which cannot be achieved by boundary loading alone. Using experiments of PDMS sheets frustrated on 3D-printed surfaces and a linearized analytical model, we demonstrate the ability of curvature to govern the sheets' fracture phenomenology. In this talk, we first show that curvature can both stimulate and suppress fracture initiation, depending on the position and orientation of the initial slit. Secondly, we show that curvature can steer the path of a crack as it propagates through the material. Lastly, the curvature can arrest cracks which would otherwise continue to propagate.

  20. Fluid Phase Separation (FPS) experiment for flight on a space shuttle Get Away Special (GAS) canister

    NASA Technical Reports Server (NTRS)

    Peters, Bruce; Wingo, Dennis; Bower, Mark; Amborski, Robert; Blount, Laura; Daniel, Alan; Hagood, Bob; Handley, James; Hediger, Donald; Jimmerson, Lisa

    1990-01-01

    The separation of fluid phases in microgravity environments is of importance to environmental control and life support systems (ECLSS) and materials processing in space. A successful fluid phase separation experiment will demonstrate a proof of concept for the separation technique and add to the knowledge base of material behavior. The phase separation experiment will contain a premixed fluid which will be exposed to a microgravity environment. After the phase separation of the compound has occurred, small samples of each of the species will be taken for analysis on the Earth. By correlating the time of separation and the temperature history of the fluid, it will be possible to characterize the process. The experiment has been integrated into space available on a manifested Get Away Special (GAS) experiment, CONCAP 2, part of the Consortium for Materials Complex Autonomous Payload (CAP) Program, scheduled for STS-42. The design and the production of a fluid phase separation experiment for rapid implementation at low cost is presented.

  1. A Temperature-Dependent Phase-Field Model for Phase Separation and Damage

    NASA Astrophysics Data System (ADS)

    Heinemann, Christian; Kraus, Christiane; Rocca, Elisabetta; Rossi, Riccarda

    2017-03-01

    In this paper we study a model for phase separation and damage in thermoviscoelastic materials. The main novelty of the paper consists in the fact that, in contrast with previous works in the literature concerning phase separation and damage processes in elastic media, in our model we encompass thermal processes, nonlinearly coupled with the damage, concentration and displacement evolutions. More particularly, we prove the existence of "entropic weak solutions", resorting to a solvability concept first introduced in uc(Feireisl) (Comput Math Appl 53:461-490, 2007) in the framework of Fourier-Navier-Stokes systems and then recently employed in uc(Feireisl) et al. (Math Methods Appl Sci 32:1345-1369, 2009) and uc(Rocca) and uc(Rossi) (Math Models Methods Appl Sci 24:1265-1341, 2014) for the study of PDE systems for phase transition and damage. Our global-in-time existence result is obtained by passing to the limit in a carefully devised time-discretization scheme.

  2. Crystalline Phase Separation in Phosphate Containing Waste Glasses: Relevance to INEEL HAW

    SciTech Connect

    Jantzen, C.M.

    2000-09-21

    As part of the Tanks Focus Area's (TFA) effort to increase waste loading for high-level waste vitrification at various facilities in the Department of Energy (DOE) complex, the occurrence of phase separation in waste glasses spanning the Savannah River Site (SRS) and Idaho National Engineering and Environmental Laboratory (INEEL) composition ranges have been studied. The type of phase separation that occurs in the phosphate rich borosilicate waste glasses, such as those investigated for INEEL, crystallizes upon cooling. This type of phase separation mechanism is less well studied than amorphous phase separation in phosphate poor borosilicate waste glasses. Therefore, the type of phase separation, extent, and impact of phase separation on glass durability for a series of INEEL-type glasses were examined and the data statistically analyzed in this study.

  3. Interplay between gelation and phase separation in aqueous solutions of methylcellulose and hydroxypropylmethylcellulose.

    PubMed

    Fairclough, J Patrick A; Yu, Hao; Kelly, Oscar; Ryan, Anthony J; Sammler, Robert L; Radler, Michael

    2012-07-17

    Thermally induced gelation in aqueous solutions of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) has been studied by rheological, optical microscopy, and turbidimetry measurements. The structural and mechanical properties of these hydrogels are dominated by the interplay between phase separation and gelation. In MC solutions, phase separation takes place almost simultaneously with gelation. An increase in the storage modulus is coupled to the appearance of a bicontinuous structure upon heating. However, a thermal gap exists between phase separation and gelation in the case of HPMC solutions. The storage modulus shows a dramatic decrease during phase separation and then rises in the subsequent gelation. A macroporous structure forms in the gels via "viscoelastic phase separation" linked to "double phase separation".

  4. A computational model for swirl vane phase separators

    NASA Astrophysics Data System (ADS)

    Lider, Serhat

    The main objective of this study is to develop a mechanistic separator-dryer model for the TRAC-BF1 code to solve the problems associated with the modeling of the steam separation phenomena. This model, in a sense, is an extension to the existing separator-dryer model in the TRAC-BF1 code. The phasic velocities and the pressures for the vapor core and the liquid film regions of the swirl vane separator are solved by the use of phasic mass and momentum equations along with pressure drop. A new dryer efficiency model is also introduced. In this model, the dryer efficiency is calculated by the corrugated plate efficiency model. The important part of the study focuses on the implementation of the separator-dryer model to the code. The implementation uses the correct convective parameters in the solution of the conservation equation for the mixing cell of separator-dryer component. The model is tested and assessed against the experimental data, an actual reactor transient, and the results of the existing model. The results indicates that the new steam separation model is more accurate and more robust when compared to the separator-dryer model.

  5. SANS study of phase separation in solid {sup 3}He-{sup 4}He

    SciTech Connect

    Koster, J.P.; Nagler, S.E.; Adams, E.D.; Wignall, G.D.

    1994-12-31

    Small angle neutron scattering has been used to study phase separation in a quantum alloy, solid {sup 3}He{sub x}-{sup 4}He{sub 1{minus}x}. The onset of phase separation is marked by a dramatic increase in the measured scattering. A simple interpretation of the results suggests that the late-stage phase separation kinetics are dominated by an increase in the concentration of {sup 3}He atoms in preexisting precipitate regions.

  6. Liquid crystal alignment with a molecular template of imprinted polymer layer during phase separation

    NASA Astrophysics Data System (ADS)

    Kim, Hak-Rin; Jung, Jong-Wook; Lee, You-Jin; Kim, Jae-Hoon

    2006-03-01

    We developed a liquid crystal (LC) alignment method using a molecular template of an imprinted polymer layer during polymerization-induced phase separation. Our results showed that the nematic ordering of LC is transferred to the polymer chain ordering during an anisotropic phase separation, which produces an anisotropic azimuthal surface anchoring. Using in-plane field treatment during phase separation, a twisted nematic cell is demonstrated.

  7. Phase separation of integral membrane proteins in Triton X-114 solution.

    PubMed

    Bordier, C

    1981-02-25

    A solution of the nonionic detergent Triton X-114 is homogeneous at 0 degrees C but separates in an aqueous phase and a detergent phase above 20 degrees C. The extent of this detergent phase separation increases with the temperature and is sensitive to the presence of other surfactants. The partition of proteins during phase separation in solutions of Triton X-114 is investigated. Hydrophilic proteins are found exclusively in the aqueous phase, and integral membrane proteins with an amphiphilic nature are recovered in the detergent phase. Triton X-114 is used to solubilize membranes and whole cells, and the soluble material is submitted to phase separation. Integral membrane proteins can thus be separated from hydrophilic proteins and identified as such in crude membrane or cellular detergent extracts.

  8. Frustrated total internal reflection acoustic field sensor

    DOEpatents

    Kallman, Jeffrey S.

    2000-01-01

    A frustrated total internal reflection acoustic field sensor which allows the acquisition of the acoustic field over an entire plane, all at once. The sensor finds use in acoustic holography and acoustic diffraction tomography. For example, the sensor may be produced by a transparent plate with transparent support members tall enough to support one or more flexible membranes at an appropriate height for frustrated total internal reflection to occur. An acoustic wave causes the membrane to deflect away from its quiescent position and thus changes the amount of light that tunnels through the gap formed by the support members and into the membrane, and so changes the amount of light reflected by the membrane. The sensor(s) is illuminated by a uniform tight field, and the reflection from the sensor yields acoustic wave amplitude and phase information which can be picked up electronically or otherwise.

  9. On separability of A-phases during the cyclic alternating pattern.

    PubMed

    Mendez, M O; Alba, A; Chouvarda, I; Milioli, G; Grassi, A; Terzano, M G; Parrino, L

    2014-01-01

    A statistical analysis of the separability of EEG A-phases, with respect to basal activity, is presented in this study. A-phases are short central events that build up the Cyclic Alternating Pattern (CAP) during sleep. The CAP is a brain phenomenon which is thought to be related to the construction, destruction and instability of sleep stages dynamics. From the EEG signals, segments obtained around the onset and offset of the A-phases were used to evaluate the separability between A-phases and basal sleep stage oscillations. In addition, a classifier was trained to separate the different A-phase types (A1, A2 and A3). Temporal, energy and complexity measures were used as descriptors for the classifier. The results show a percentage of separation between onset and preceding basal oscillations higher than 85 % for all A-phases types. For Offset separation from following baseline, the accuracy is higher than 80 % but specificity is around 75%. Concerning to A-phase type separation, A1-phase and A3-phase are well separated with accuracy higher than 80, while A1 and A2-phases show a separation lower than 50%. These results encourage the design of automatic classifiers for Onset detection and for separating among A-phases type A1 and A3. On the other hand, the A-phase Offsets present a smooth transition towards the basal sleep stage oscillations, and A2-phases are very similar to A1-phases, suggesting that a high uncertainty may exist during CAP annotation.

  10. Formation of binary phase gratings in photopolymer-liquid crystal composites by a surface-controlled anisotropic phase separation

    SciTech Connect

    Park, Jae-Hong; Khoo, Iam Choon; Yu, Chang-Jae; Jung, Min-Sik; Lee, Sin-Doo

    2005-01-10

    We report on formation of binary phase gratings in photopolymer-liquid crystal (PLC) composites using a surface-controlled phase separation method. The binary nature of the PLC phase gratings is produced by employing a single step photo-ablation through an amplitude photomask which precisely controls the interfacial interactions between the LC and the photopolymer on the alignment layer. A subsequent illumination of the ultraviolet light onto the whole PLC promotes an anisotropic phase separation resulting in the formation of distinct binary patterns for the PLC structure. The electrically tunable diffraction properties of the binary phase gratings are presented.

  11. Two-phase, passive separator-and-filter assembly

    NASA Technical Reports Server (NTRS)

    Erickson, A. C.; Porter, F. J., Jr.

    1974-01-01

    Assembly separates liquid from gas by passive hydrophilic/hydrophobic material approach. Apparatus is comprised of porous glass hydrophilic tubes. Quantity, lateral size, and pore size of glass tubes are determined by particular design requirements with regard to water rate, water quality contamination level, application endurance life, and operating differential pressure level.

  12. Separations/pretreatment considerations for Hanford privatization phase 2

    SciTech Connect

    Hunt, R.D.; McGinnis, C.P.; Welch, T.D.

    1998-05-01

    The Tank Focus Area is funded to develop, demonstrate, and deploy technologies that will assist in the treatment and closure of its nuclear waste tanks. Pretreatment technologies developed to support the privatization effort by the Department of Energy are reviewed. Advancements in evaporation, solid-liquid separation, sludge treatment, solids controls, sodium management, and radionuclide removal are considered.

  13. Phase separation in lipid bilayers triggered by low pH

    SciTech Connect

    Suresh, Swetha; Edwardson, J. Michael

    2010-09-03

    Research highlights: {yields} Lipid bilayers have been imaged by atomic force microscopy (AFM). {yields} At pH 5 phase separation occurs in lipid bilayers containing mixed acyl chains. {yields} Phase separation does not occur when lipids have only unsaturated chains. {yields} Phase separation might drive protein clustering during endocytosis. -- Abstract: Endocytosis involves the capture of membrane from the cell surface in the form of vesicles, which become rapidly acidified to about pH 5. Here we show using atomic force microscopy (AFM) imaging that this degree of acidification triggers phase separation in lipid bilayers containing mixed acyl chains (e.g. palmitoyl/oleoyl) or complex mixtures (e.g. total brain extract) but not in bilayers containing only lipids with unsaturated chains (e.g. dioleoyl). Since mixed-chain lipids are major constituents of the outer leaflet of the plasma membrane, the type of phase separation reported here might support protein clustering and signaling during endocytosis.

  14. Vertical phase separation in bulk heterojunction solar cells formed by in situ polymerization of fulleride

    PubMed Central

    Zhang, Lipei; Xing, Xing; Zheng, Lingling; Chen, Zhijian; Xiao, Lixin; Qu, Bo; Gong, Qihuang

    2014-01-01

    Vertical phase separation of the donor and the acceptor in organic bulk heterojunction solar cells is crucial to improve the exciton dissociation and charge transport efficiencies. This is because whilst the exciton diffusion length is limited, the organic film must be thick enough to absorb sufficient light. However, it is still a challenge to control the phase separation of a binary blend in a bulk heterojunction device architecture. Here we report the realization of vertical phase separation induced by in situ photo-polymerization of the acrylate-based fulleride. The power conversion efficiency of the devices with vertical phase separation increased by 20%. By optimising the device architecture, the power conversion efficiency of the single junction device reached 8.47%. We believe that in situ photo-polymerization of acrylate-based fulleride is a universal and controllable way to realise vertical phase separation in organic blends. PMID:24861168

  15. Pinning of phase separation of aqueous solution of hydroxypropylmethylcellulose by gelation

    NASA Astrophysics Data System (ADS)

    Kita, Rio; Kaku, Takeshi; Kubota, Kenji; Dobashi, Toshiaki

    1999-08-01

    Opalescence of the aqueous solution of hydroxypropylmethylcellulose (HPMC) induced by heating has been studied in terms of the phase diagram and the phase separation dynamics. The cloud point curve and the sol-to-gel transition curve intersected with each other at about 55 °C. Just above the cloud-point curve at which the spinodal curve has its minimum, a ring-like scattering pattern appeared corresponding to the spinodal decomposition. Temporal growth of the scattering function in the course of phase separation was studied by a time-resolved light scattering technique. The gelation pinned the phase separation (spinodal decomposition) of the aqueous HPMC solution.

  16. Demixing kinetics of phase separated polymer solutions in microgravity. [cell separation

    NASA Technical Reports Server (NTRS)

    Brooks, D. E.; Bamberger, S. B.; Harris, J. M.; Vanalstine, J.; Snyder, R. S.

    1987-01-01

    In preparation for performing cell partitioning in space the demixing behavior of aqueous two phase systems containing dextran and poly(ethylene glycol) in microgravity was modeled with an isopycnic system and studied on aircraft flights and on STS 51-D. In all types of experiments demixing occurs, eventually producing one phase localized around the wall of the container with the other internalized within it. The demixing kinetics were analyzed in each case.

  17. Kinetics of phase separation and coarsening in dilute surfactant pentaethylene glycol monododecyl ether solutions.

    PubMed

    Tanaka, S; Kubo, Y; Yokoyama, Y; Toda, A; Taguchi, K; Kajioka, H

    2011-12-21

    We investigated the phase separation phenomena in dilute surfactant pentaethylene glycol monodedecyl ether (C(12)E(5)) solutions focusing on the growth law of separated domains. The solutions confined between two glass plates were found to exhibit the phase inversion, characteristic of the viscoelastic phase separation; the majority phase (water-rich phase) nucleated as droplets and the minority phase (micelle-rich phase) formed a network temporarily, then they collapsed into an usual sea-island pattern where minority phase formed islands. We found from the real-space microscopic imaging that the dynamic scaling hypothesis did not hold throughout the coarsening process. The power law growth of the domains with the exponent close to 1/3 was observed even though the coarsening was induced mainly by hydrodynamic flow, which was explained by Darcy's law of laminar flow.

  18. Gaussian noise and the two-network frustrated Kuramoto model

    NASA Astrophysics Data System (ADS)

    Holder, Andrew B.; Zuparic, Mathew L.; Kalloniatis, Alexander C.

    2017-02-01

    We examine analytically and numerically a variant of the stochastic Kuramoto model for phase oscillators coupled on a general network. Two populations of phased oscillators are considered, labelled 'Blue' and 'Red', each with their respective networks, internal and external couplings, natural frequencies, and frustration parameters in the dynamical interactions of the phases. We disentangle the different ways that additive Gaussian noise may influence the dynamics by applying it separately on zero modes or normal modes corresponding to a Laplacian decomposition for the sub-graphs for Blue and Red. Under the linearisation ansatz that the oscillators of each respective network remain relatively phase-synchronised centroids or clusters, we are able to obtain simple closed-form expressions using the Fokker-Planck approach for the dynamics of the average angle of the two centroids. In some cases, this leads to subtle effects of metastability that we may analytically describe using the theory of ratchet potentials. These considerations are extended to a regime where one of the populations has fragmented in two. The analytic expressions we derive largely predict the dynamics of the non-linear system seen in numerical simulation. In particular, we find that noise acting on a more tightly coupled population allows for improved synchronisation of the other population where deterministically it is fragmented.

  19. Colloquium: Artificial spin ice: Designing and imaging magnetic frustration

    NASA Astrophysics Data System (ADS)

    Nisoli, Cristiano; Moessner, Roderich; Schiffer, Peter

    2013-10-01

    Frustration, the presence of competing interactions, is ubiquitous in the physical sciences and is a source of degeneracy and disorder, which in turn gives rise to new and interesting physical phenomena. Perhaps nowhere does it occur more simply than in correlated spin systems, where it has been studied in the most detail. In disordered magnetic materials, frustration leads to spin-glass phenomena, with analogies to the behavior of structural glasses and neural networks. In structurally ordered magnetic materials, it has also been the topic of extensive theoretical and experimental studies over the past two decades. Such geometrical frustration has opened a window to a wide range of fundamentally new exotic behavior. This includes spin liquids in which the spins continue to fluctuate down to the lowest temperatures, and spin ice, which appears to retain macroscopic entropy even in the low-temperature limit where it enters a topological Coulomb phase. In the past seven years a new perspective has opened in the study of frustration through the creation of artificial frustrated magnetic systems. These materials consist of arrays of lithographically fabricated single-domain ferromagnetic nanostructures that behave like giant Ising spins. The nanostructures’ interactions can be controlled through appropriate choices of their geometric properties and arrangement on a (frustrated) lattice. The degrees of freedom of the material can not only be directly tuned, but also individually observed. Experimental studies have unearthed intriguing connections to the out-of-equilibrium physics of disordered systems and nonthermal “granular” materials, while revealing strong analogies to spin ice materials and their fractionalized magnetic monopole excitations, lending the enterprise a distinctly interdisciplinary flavor. The experimental results have also been closely coupled to theoretical and computational analyses, facilitated by connections to classic models of frustrated

  20. Controllable Phase Separation by Boc-Modified Lipophilic Acid as a Multifunctional Extractant

    NASA Astrophysics Data System (ADS)

    Tao, Kai; Adler-Abramovich, Lihi; Gazit, Ehud

    2015-12-01

    While phase separation of immiscible liquid-liquid systems has become increasingly significant in diverse areas, the irreversible nature limits their further application in controllable extraction-concentration or capture-release fields. There is a need for the development of simple, efficient and reversible methods for numerous research and industrial extraction and separation applications. We envisioned Boc-modified lipophilic acids as a simple model for such use based on the studies of the multi-phase transitions of Boc-modified supramolecular polymeric systems. Here, we demonstrate that in the presence of Boc-7-aminoheptanoic acid (Boc-7), phase separation occurs in mixtures of miscible organic solvent and water. The separation behavior was confirmed by differential colorimetric development in aqueous and organic phases using methyl orange staining assays. Component substitution experiments verified that the phase separation results from the subtle balance between the aggregation and the solvation forces of Boc-7, and is reversible by adjusting the solution pH. Owing to the intrinsic hydrophobic properties of the organic phase and the hydrogen bonding-forming ability of the carboxyl group of Boc-7, the phase separation system captures and releases Sudan Red, fluorescein, and streptavidin in a controllable manner. Consequently, a reversible and simple phase separation system can be designed as a multifunctional extractant.

  1. Controllable Phase Separation by Boc-Modified Lipophilic Acid as a Multifunctional Extractant

    PubMed Central

    Tao, Kai; Adler-Abramovich, Lihi; Gazit, Ehud

    2015-01-01

    While phase separation of immiscible liquid-liquid systems has become increasingly significant in diverse areas, the irreversible nature limits their further application in controllable extraction-concentration or capture-release fields. There is a need for the development of simple, efficient and reversible methods for numerous research and industrial extraction and separation applications. We envisioned Boc-modified lipophilic acids as a simple model for such use based on the studies of the multi-phase transitions of Boc-modified supramolecular polymeric systems. Here, we demonstrate that in the presence of Boc-7-aminoheptanoic acid (Boc-7), phase separation occurs in mixtures of miscible organic solvent and water. The separation behavior was confirmed by differential colorimetric development in aqueous and organic phases using methyl orange staining assays. Component substitution experiments verified that the phase separation results from the subtle balance between the aggregation and the solvation forces of Boc-7, and is reversible by adjusting the solution pH. Owing to the intrinsic hydrophobic properties of the organic phase and the hydrogen bonding-forming ability of the carboxyl group of Boc-7, the phase separation system captures and releases Sudan Red, fluorescein, and streptavidin in a controllable manner. Consequently, a reversible and simple phase separation system can be designed as a multifunctional extractant. PMID:26627307

  2. Topological Phases of the Spin-1/2 Ferromagnetic--Antiferromagnetic Alternating Heisenberg Chain with Frustrated Next-Nearest-Neighbour Interaction

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Takano, Ken'ichi; Suzuki, Hidenori

    2013-06-01

    The spin-1/2 ferromagnetic--antiferromagnetic alternating Heisenberg chain with ferromagnetic next-nearest-neighbour (NNN) interaction is investigated. The ground state is the Haldane phase for weak NNN interaction, and is the ferromagnetic phase for weak antiferromagnetic interaction. We find a series of topologically distinct spin-gap phases with various magnitudes of edge spins for strong NNN interaction. The phase boundaries between these phases are determined on the basis of the DMRG calculation with additional spins that compensate the edge spins. It is found that each of the exact solutions with short-range antiferromagnetic correlation on the ferromagnetic--nonmagnetic phase boundary is representative of each spin gap phase.

  3. Phase separation in garnet solid solutions and its effect on optical properties.

    PubMed

    Kaveh, Shakiba; Tremblay, Clément P; Norhashim, Nurhakimah; Curry, Richard J; Cheetham, Anthony K

    2013-11-26

    Phase behavior is studied in erbium-doped Y3 Al5 O12 (YAG) garnets synthesized by solid-state reactions. High resolution synchrotron XRD and SEM-EDX studies reveal phase separation at an erbium content between 8 and 50 at%, depending upon the processing conditions. Similar results are found in closely-related garnet systems. The phase separation has a striking effect on the optical properties of YAG:Er(3+) .

  4. Separation of piracetam derivatives on polysaccharide-based chiral stationary phases.

    PubMed

    Kažoka, H; Koliškina, O; Veinberg, G; Vorona, M

    2013-03-15

    High-performance liquid chromatography was used for the enantiomeric separation of two chiral piracetam derivatives. The suitability of six commercially available polysaccharide-based chiral stationary phases (CSPs) under normal phase mode for direct enantioseparation has been investigated. The influence of the CSPs as well the nature and content of an alcoholic modifier in the mobile phase on separation and elution order was studied. It was established that CSP Lux Amylose-2 shows high chiral recognition ability towards 4-phenylsubstituted piracetam derivatives.

  5. Phase conversion and interface growth in phase-separated 3He - 4He liquid mixtures

    NASA Astrophysics Data System (ADS)

    Abe, Haruka; Satoh, Takeo; Burmistrov, Serguei N.

    2005-10-01

    We have developed a method for measuring the transmission coefficient of a sound propagating through the interface in phase-separated He3-He4 liquid mixtures. The method and the results are described with discussions by examining the phase-conversion process of He3 quasiparticles driven to flow across the interface. From the data, we have determined the kinetic growth coefficient of the interface, ξ(T,P,ω) , as a function of temperature, pressure, and frequency. The temperature range of the present investigation is about 2-100mK at the pressure mainly around 1bar with sound frequency 9.64, 14.4, and 32.4MHz . The main specific features observed for the kinetic growth coefficient are, as follows: (i) there is a maximum at some temperature Tm(ω) depending on the frequency, (ii) above Tm(ω) , ξ decreases with the increase of temperature as ∝ω5/2T-3 , and (iii) below Tm(ω) , ξ becomes frequency independent and diminishes as a cube of temperature, T3 .

  6. Effects of attractive colloids on the phase separation behaviors of binary polymer blends

    NASA Astrophysics Data System (ADS)

    Zhang, Xinghua; Chen, Yunlin; Qu, Lijian; Yan, Dadong

    2013-08-01

    The attractive colloids are added as fillers to control the phase behaviors of binary polymer blends. Because the colloids attract both components in the blends, aggregates are formed by the colloids coated with both kinds of polymer brushes. The aggregation results in two contradictory effects on the phase separation. First, the formation of aggregate decreases the translational entropy, which promotes the phase separation. On the other hand, the phase separation causes the extra free energy penalty due to the stretch of the chains attaching on the colloids, which prevents the phase separation. Furthermore, as the concentration or adsorbability of the colloids increases the local fluctuations within the aggregates become important. This results in a transition from the macro-phase separation to the micro-phase separation and the existence of the Lifshitz point. All of these effects lead to diverse phase behaviors in the polymer nanocomposites system. In present work, these behaviors are studied theoretically by the random phase approximation in a model system.

  7. Slow Thermodynamics in the Phase Separated State of the Bilayered Manganite (La0.4Pr0.6)1.2Sr1.8Mn2O7

    NASA Astrophysics Data System (ADS)

    Taniguchi, Haruka; Nakamura, Yuma; Konno, Takahisa; Matsukawa, Michiaki; Suryanarayanan, Ramanathaan

    Bilayered perovskite (La0.4Pr0.6)1.2Sr1.8Mn2O7 exhibits a field-induced paramagnetic-insulator to ferromagnetic- metal transition, and a phase-separated state is realized after the field is switched off. In order to clarify the thermodynamic properties of the phase-separated state which is a common feature in many mangan- ites, we performed specific heat measurement with field along the magnetization easy axis. We have revealed that the remanent specifc heat might exhibit a stretched exponential decay and the relaxation time is remarkably long. These results indicate the importance of magnetic frustration originating from the competition between double-exchange interaction and superexchange interaction.

  8. Frustration-induced nanometre-scale inhomogeneity in a triangular antiferromagnet

    PubMed Central

    Zorko, A.; Adamopoulos, O.; Komelj, M.; Arčon, D.; Lappas, A.

    2014-01-01

    Phase inhomogeneity of otherwise chemically homogenous electronic systems is an essential ingredient leading to fascinating functional properties, such as high-Tc superconductivity in cuprates, colossal magnetoresistance in manganites and giant electrostriction in relaxors. In these materials distinct phases compete and can coexist owing to intertwined ordered parameters. Charge degrees of freedom play a fundamental role, although phase-separated ground states have been envisioned theoretically also for pure spin systems with geometrical frustration that serves as a source of phase competition. Here we report a paradigmatic magnetostructurally inhomogenous ground state of the geometrically frustrated α-NaMnO2 that stems from the system’s aspiration to remove magnetic degeneracy and is possible only due to the existence of near-degenerate crystal structures. Synchrotron X-ray diffraction, nuclear magnetic resonance and muon spin relaxation show that the spin configuration of a monoclinic phase is disrupted by magnetically short-range-ordered nanoscale triclinic regions, thus revealing a novel complex state of matter. PMID:24477185

  9. Frustration in Condensed Matter and Protein Folding

    NASA Astrophysics Data System (ADS)

    Li, Z.; Tanner, S.; Conroy, B.; Owens, F.; Tran, M. M.; Boekema, C.

    2014-03-01

    By means of computer modeling, we are studying frustration in condensed matter and protein folding, including the influence of temperature and Thomson-figure formation. Frustration is due to competing interactions in a disordered state. The key issue is how the particles interact to reach the lowest frustration. The relaxation for frustration is mostly a power function (randomly assigned pattern) or an exponential function (regular patterns like Thomson figures). For the atomic Thomson model, frustration is predicted to decrease with the formation of Thomson figures at zero kelvin. We attempt to apply our frustration modeling to protein folding and dynamics. We investigate the homogeneous protein frustration that would cause the speed of the protein folding to increase. Increase of protein frustration (where frustration and hydrophobicity interplay with protein folding) may lead to a protein mutation. Research is supported by WiSE@SJSU and AFC San Jose.

  10. In situ imaging and height reconstruction of phase separation processes in polymer blends during spin coating.

    PubMed

    Ebbens, Stephen; Hodgkinson, Richard; Parnell, Andrew J; Dunbar, Alan; Martin, Simon J; Topham, Paul D; Clarke, Nigel; Howse, Jonathan R

    2011-06-28

    Spin coating polymer blend thin films provides a method to produce multiphase functional layers of high uniformity covering large surface areas. Applications for such layers include photovoltaics and light-emitting diodes where performance relies upon the nanoscale phase separation morphology of the spun film. Furthermore, at micrometer scales, phase separation provides a route to produce self-organized structures for templating applications. Understanding the factors that determine the final phase-separated morphology in these systems is consequently an important goal. However, it has to date proved problematic to fully test theoretical models for phase separation during spin coating, due to the high spin speeds, which has limited the spatial resolution of experimental data obtained during the coating process. Without this fundamental understanding, production of optimized micro- and nanoscale structures is hampered. Here, we have employed synchronized stroboscopic illumination together with the high light gathering sensitivity of an electron-multiplying charge-coupled device camera to optically observe structure evolution in such blends during spin coating. Furthermore the use of monochromatic illumination has allowed interference reconstruction of three-dimensional topographies of the spin-coated film as it dries and phase separates with nanometer precision. We have used this new method to directly observe the phase separation process during spinning for a polymer blend (PS-PI) for the first time, providing new insights into the spin-coating process and opening up a route to understand and control phase separation structures.

  11. Thermophysical properties of fluorinated acrylate homopolymers: Mixing and phase separation

    NASA Astrophysics Data System (ADS)

    Roussel, F.; Saidi, S.; Guittard, F.; Geribaldi, S.

    2002-06-01

    The thermophysical properties of fluorinated acrylate homopolymers are investigated by differential scanning calorimetry (DSC) and optical microscopy and discussed in terms of relative lengths of the fluorinated chain and the hydrocarbon spacer between the acrylate moiety and the fluorinated chain. These compounds exhibit an intrinsic microphase-separation (Isotropic+Isotropic morphology) occurring between the fluorinated chains and the acrylate polymer backbone. It is shown that the enthalpy of mixing is a function of the length of the lateral fluorocarbon chains. The thermophysical behaviour of these materials may be regarded as demixed systems exhibiting an Upper Critical Solution Temperature. The photopolymerization process of one of the monomer is studied by isothermal photocalorimetry. High acrylate double-bond conversion and fast curing rates were obtained thus demonstrating the promising use of these materials for coating and film processing applications using UV-curing techniques.

  12. Excitations in the quantum paramagnetic phase of the quasi-one-dimensional Ising magnet CoNb2O6 in a transverse field: Geometric frustration and quantum renormalization effects

    NASA Astrophysics Data System (ADS)

    Cabrera, Ivelisse; Thompson, J. D.; Coldea, R.; Prabhakaran, D.; Bewley, R. I.; Guidi, T.; Rodriguez-Rivera, J. A.; Stock, C.

    We report extensive single-crystal inelastic neutron scattering measurements of the magnetic excitations in the quasi 1D Ising ferromagnet CoNb2O6 in the quantum paramagnetic phase to characterize the effects of the finite interchain couplings. In this phase, we observe that excitations have a sharp, resolution-limited line shape at low energies and over most of the dispersion bandwidth, as expected for spin-flip quasiparticles. We map the full bandwidth along the strongly dispersive chain direction and resolve clear modulations of the dispersions in the plane normal to the chains, characteristic of frustrated interchain couplings in an antiferromagnetic isosceles triangular lattice. The dispersions can be well parametrized using a linear spin-wave model that includes interchain couplings and further neighbor exchanges. The observed dispersion bandwidth along the chain direction is smaller than that predicted by a linear spin-wave model using exchange values determined at zero field. We attribute this effect to quantum renormalization of the dispersion beyond the spin-wave approximation in fields slightly above the critical field, where quantum fluctuations are still significant. We acknowledge support from EPSRC Grant No. EP/H014934/1, the Oxford Clarendon Fund Scholarship and NSERC of Canada.

  13. Soft nanostructuring of YBCO Josephson junctions by phase separation.

    PubMed

    Gustafsson, D; Pettersson, H; Iandolo, B; Olsson, E; Bauch, T; Lombardi, F

    2010-12-08

    We have developed a new method to fabricate biepitaxial YBa2 Cu3 O7-δ (YBCO) Josephson junctions at the nanoscale, allowing junctions widths down to 100 nm and simultaneously avoiding the typical damage in grain boundary interfaces due to conventional patterning procedures. By using the competition between the superconducting YBCO and the insulating Y2 BaCuO5 phases during film growth, we formed nanometer sized grain boundary junctions in the insulating Y2 BaCuO5 matrix as confirmed by high-resolution transmission electron microscopy. Electrical transport measurements give clear indications that we are close to probing the intrinsic properties of the grain boundaries.

  14. Frustration behaviors in domestic dogs.

    PubMed

    Jakovcevic, Adriana; Elgier, Angel M; Mustaca, Alba E; Bentosela, Mariana

    2013-01-01

    During extinction a previously learned behavior stops being reinforced. In addition to the decrease in the rate of the instrumental response, it produces an aversive emotional state known as frustration. This state can be assimilated with the fear reactions that occur after aversive stimuli are introduced at both the physiological and behavioral levels. This study evaluated frustration reactions of domestic dogs (Canis familiaris) during a communicative situation involving interactions with a human. The task included the reinforcement and extinction of the gaze response toward the experimenter's face when the dogs tried to obtain inaccessible food. The dog's frustration reactions during extinction involved an increase in withdrawal and side orientation to the location of the human as well as lying down, ambulation, sniffing, and vocalizations compared with the last acquisition trial. These results are especially relevant for domestic dog training situations in which the extinction technique is commonly used to discourage undesirable behaviors.

  15. Formation of ion clusters in the phase separated structures of neutral-charged polymer blends

    NASA Astrophysics Data System (ADS)

    Kwon, Ha-Kyung; Olvera de La Cruz, Monica

    2015-03-01

    Polyelectrolyte blends, consisting of at least one charged species, are promising candidate materials for fuel cell membranes, for their mechanical stability and high selectivity for proton conduction. The phase behavior of the blends is important to understand, as this can significantly affect the performance of the device. The phase behavior is controlled by χN, the Flory-Huggins parameter multiplied by the number of mers, as well as the electrostatic interactions between the charged backbone and the counterions. It has recently been shown that local ionic correlations, incorporated via liquid state (LS) theory, enhance phase separation of the blend, even in the absence of polymer interactions. In this study, we show phase diagrams of neutral-charged polymer blends including ionic correlations via LS theory. In addition to enhanced phase separation at low χN, the blends show liquid-liquid phase separation at high electrostatic interaction strengths. Above the critical strength, the charged polymer phase separates into ion-rich and ion-poor regions, resulting in the formation of ion clusters within the charged polymer phase. This can be shown by the appearance of multiple spinodal and critical points, indicating the coexistence of several charge separated phases. This work was performed under the following financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).

  16. A fuzzy controlled three-phase centrifuge for waste separation

    SciTech Connect

    Parkinson, W.J.; Smith, R.E.; Miller, N.

    1998-02-01

    The three-phase centrifuge technology discussed in this paper was developed by Neal Miller, president of Centech, Inc. The three-phase centrifuge is an excellent device for cleaning up oil field and refinery wastes which are typically composed of hydrocarbons, water, and solids. The technology is unique. It turns the waste into salable oil, reusable water, and landfill-able solids. No secondary waste is produced. The problem is that only the inventor can set up and run the equipment well enough to provide an optimal cleanup. Demand for this device has far exceeded a one man operation. There is now a need for several centrifuges to be operated at different locations at the same time. This has produced a demand for an intelligent control system, one that could replace a highly skilled operator, or at least supplement the skills of a less experienced operator. The control problem is ideally suited to fuzzy logic, since the centrifuge is a highly complicated machine operated entirely by the skill and experience of the operator. A fuzzy control system was designed for and used with the centrifuge.

  17. Cell separations and the demixing of aqueous two phase polymer solutions in microgravity

    NASA Technical Reports Server (NTRS)

    Brooks, Donald E.; Bamberger, Stephan; Harris, J. M.; Van Alstine, James M.

    1991-01-01

    Partition in phase separated aqueous polymer solutions is a cell separation procedure thought to be adversely influenced by gravity. In preparation for performing cell partitioning experiments in space, and to provide general information concerning the demixing of immiscible liquids in low gravity, a series of phase separated aqueous polymer solutions have been flown on two shuttle flights. Fluorocarbon oil and water emulsions were also flown on the second flight. The aqueous polymer emulsions, which in one g demix largely by sedimentation and convection due to the density differences between the phases, demixed more slowly than on the ground and the final disposition of the phases was determined by the wetting of the container wall by the phases. The demixing behavior and kinetics were influenced by the phase volume ratio, physical properties of the systems and chamber wall interaction. The average domain size increased linearly with time as the systems demixed.

  18. Phase behavior and molecular dynamics simulation studies of new aqueous two-phase separation systems induced by HEPES buffer.

    PubMed

    Taha, Mohamed; Khoiroh, Ianatul; Lee, Ming-Jer

    2013-01-17

    Here, for the first time, we show that with addition of a biological buffer, 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid (HEPES), into aqueous solutions of tetrahydrofuran (THF), 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone, the organic solvent can be excluded from water to form a new liquid phase. The phase diagrams have been determined at ambient temperature. In order to understand why and how a zwitterion solute (HEPES) induced phase separation of the investigated systems, molecular dynamics (MD) simulation studies are performed for HEPES + water + THF system. The MD simulations were conducted for the aqueous mixtures with 12 different compositions. The reliability of the simulation results of HEPES in pure water and beyond the phase separation mixtures was justified by comparing the densities obtained from MD with the experimental values. The simulation results of HEPES in pure THF and in a composition inside the phase separation region were justified qualitatively. Interestingly, all HEPES molecules entirely aggregated in pure THF. This reveals that HEPES is insoluble in pure THF, which is consistent with the experimental results. Even more interestingly, the MD simulation for the mixture with composition inside the phase separation region showed the formation of two phases. The THF molecules are squeezed out from the water network into a new liquid phase. The hydrogen bonds (HBs), HB lifetime, HB Gibbs energy (ΔG), radial distribution functions (RDFs), coordination numbers (CNs), electrostatic interactions, and the van der Waals interactions between the different species have been analyzed. Further, MD simulations for the other phase separation systems by choosing a composition inside the two liquids region for each system were also simulated. Our findings will therefore pave the way for designing new benign separation auxiliary agents.

  19. Tuning magnetism by Kondo effect and frustration

    NASA Astrophysics Data System (ADS)

    Löhneysen, Hilbert V.

    2014-03-01

    Heavy-fermion systems are an ideal playground for studying the quantum phase transition (QPT) between paramagnetic and magnetically ordered ground states arising from the competition between Kondo and RKKY interactions. Two different routes have been identified by various experiments, i. e., the more traditional spin-density-wave (SDW) and the Kondo-breakdown approaches. However, up to now an a-priori assignment of a given system to these different routes has not been possible. Yet another route to quantum criticality not included in the above approaches might be geometric frustration of magnetic moments, a route well known for insulating magnets with competing interactions. First experiments on metallic systems have recently been conducted. In the canonical partially frustrated antiferromagnetic system CePd1-xNixAl, the Néel temperature TN(x) decreases, with TN --> 0 at the critical concentration xc ~ 0.144. The low-temperature specific heat C(T) evolves toward C/ Tα ln(T0/ T) for x -->xc. The unusual T dependence of C/ T is compatible with the Hertz-Millis-Moriya (HMM) scenario of quantum criticality if the quantum-critical fluctuations are two-dimensional in nature. Here two-dimensionality might arise from antiferromagnetic planes that are effectively decoupled by the frustrated Ce atoms in between. An exciting possibility is that the planes of frustrated Ce moments form a two-dimensional spin liquid. In the prototypical heavy-fermion system CeCu6-xAux the experiments by Schröder et al. provided the initial evidence of local quantum criticality. While concentration and pressure tuning of the quantum phase transition (QPT) are described by this scenario, magnetic-field tuning the QPT is in line with the SDW scenario. Elastic neutron scattering experiments on CeCu5.5Au0.5 under hydrostatic pressure p show that at p = 8 kbar, TN and the magnetic propagation vector attain almost the values of CeCu5.7Au0.3. This x - p analogy away from the QPT is highly remarkable

  20. Phase separation in star-linear polymer mixtures.

    PubMed

    Camargo, Manuel; Likos, Christos N

    2009-05-28

    We study mixtures of star polymers and linear chains in good solvent conditions. We consider the effect of the addition of small chains on the equilibrium structure as well as on the phase behavior of low- and intermediate-functionality star solutions. By using a recently introduced effective cross interaction between stars and chains [C. Mayer and C. N. Likos, Macromolecules 40, 1196 (2007)], we solve the two-component Ornstein-Zernike equation, finding evidence for cluster formation, which is accompanied by a spinodal instability at moderate chain concentrations. The binodal lines are numerically calculated and the dependence of the observed phenomena on functionality, size, and concentrations is rationalized by considering the attractive contribution, which is displayed by the effective, chain-modified star-star interaction potential.

  1. Phase Separation and Crystallization of Hemoglobin C in Transgenic Mouse and Human Erythrocytes

    PubMed Central

    Canterino, Joseph E.; Galkin, Oleg; Vekilov, Peter G.; Hirsch, Rhoda Elison

    2008-01-01

    Individuals expressing hemoglobin C (β6 Glu→Lys) present red blood cells (RBC) with intraerythrocytic crystals that form when hemoglobin (Hb) is oxygenated. Our earlier in vitro liquid-liquid (L-L) phase separation studies demonstrated that liganded HbC exhibits a stronger net intermolecular attraction with a longer range than liganded HbS or HbA, and that L-L phase separation preceded and enhanced crystallization. We now present evidence for the role of phase separation in HbC crystallization in the RBC, and the role of the RBC membrane as a nucleation center. RBC obtained from both human homozygous HbC patients and transgenic mice expressing only human HbC were studied by bright-field and differential interference contrast video-enhanced microscopy. RBC were exposed to hypertonic NaCl solution (1.5–3%) to induce crystallization within an appropriate experimental time frame. L-L phase separation occurred inside the RBC, which in turn enhanced the formation of intraerythrocytic crystals. RBC L-L phase separation and crystallization comply with the thermodynamic and kinetics laws established through in vitro studies of phase transformations. This is the first report, to the best of our knowledge, to capture a temporal view of intraerythrocytic HbC phase separation, crystal formation, and dissolution. PMID:18621841

  2. Applied catastrophic phase inversion: a continuous non-centrifugal phase separation step in biphasic whole-cell biocatalysis.

    PubMed

    Glonke, Sebastian; Sadowski, Gabriele; Brandenbusch, Christoph

    2016-11-01

    Biphasic whole-cell biotransformations are known to be efficient alternatives to common chemical synthesis routes, especially for the production of, e.g. apolar enantiopure organic compounds. They provide high stereoselectivity combined with high product concentrations owing to the presence of an organic phase serving as substrate reservoir and product sink. Industrial implementation suffers from the formation of stable Pickering emulsions caused by the presence of cells. State-of-the-art downstream processing includes inefficient strategies such as excessive centrifugation, use of de-emulsifiers or thermal stress. In contrast, using the catastrophic phase inversion (CPI) phenomenon (sudden switch of emulsion type caused by addition of dispersed phase), Pickering-type emulsions can be destabilized efficiently. Within this work a model system using bis(2-ethylhexyl) phthalate (BEHP) as organic phase in combination with E. coli, JM101 was successfully separated using a continuous mixer settler setup. Compared to the state-of-the-art centrifugal separations, this process allows complete phase separation with no detectable water content or cells in the organic phase with no utilities/additives required. Furthermore, the concentration of the product is not affected by the separation. It is therefore a simple applicable method that can be used for separation of stable Pickering-type emulsions based on the knowledge of the point of inversion.

  3. Hierarchical multiscale hyperporous block copolymer membranes via tunable dual-phase separation.

    PubMed

    Yoo, Seungmin; Kim, Jung-Hwan; Shin, Myoungsoo; Park, Hyungmin; Kim, Jeong-Hoon; Lee, Sang-Young; Park, Soojin

    2015-07-01

    The rational design and realization of revolutionary porous structures have been long-standing challenges in membrane science. We demonstrate a new class of amphiphilic polystyrene-block-poly(4-vinylpyridine) block copolymer (BCP)-based porous membranes featuring hierarchical multiscale hyperporous structures. The introduction of surface energy-modifying agents and the control of major phase separation parameters (such as nonsolvent polarity and solvent drying time) enable tunable dual-phase separation of BCPs, eventually leading to macro/nanoscale porous structures and chemical functionalities far beyond those accessible with conventional approaches. Application of this BCP membrane to a lithium-ion battery separator affords exceptional improvement in electrochemical performance. The dual-phase separation-driven macro/nanopore construction strategy, owing to its simplicity and tunability, is expected to be readily applicable to a rich variety of membrane fields including molecular separation, water purification, and energy-related devices.

  4. Multimodal Responses of Self-Organized Circuitry in Electronically Phase Separated Materials

    SciTech Connect

    Herklotz, Andreas; Guo, Hangwen; Wong, Anthony T.; Lee, Ho Nyung; Rack, Philip D.; Ward, Thomas Z.

    2016-07-13

    When confining an electronically phase we separated manganite film to the scale of its coexisting self-organized metallic and these insulating domains allows resistor-capacitor circuit-like responses while providing both electroresistive and magnetoresistive switching functionality.

  5. HPLC SEPARATION OF CHIRAL ORGANOPHOSPHORUS PESTICIDES ON POLYSACCHARIDE CHIRAL STATIONARY PHASES

    EPA Science Inventory

    High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) were obtained on polysaccharide chiral HPLC columns using an alkane-alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, dyfonate, fenamiphos, ...

  6. An asymmetric tubular ceramic-carbonate dual phase membrane for high temperature CO2 separation.

    PubMed

    Dong, Xueliang; Ortiz Landeros, José; Lin, Y S

    2013-10-25

    For the first time, a tubular asymmetric ceramic-carbonate dual phase membrane was prepared by a centrifugal casting technique and used for high temperature CO2 separation. This membrane shows high CO2 permeation flux and permeance.

  7. HIGH PERFORMANCE LIQUID CHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF ORGANOPHOSPHORUS PESTICIDES ON POLYSACCHARIDE CHIRAL STATIONARY PHASES

    EPA Science Inventory

    High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) was obtained on polysaccharide enantioselective HPLC columns using alkane-alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, fonofos, fenamiph...

  8. The effect of liquid-liquid phase separation of glass on the properties and crystallization behavior

    NASA Technical Reports Server (NTRS)

    Li, J. Z.

    1985-01-01

    A theoretical discussion is given of the phase separation mechanism of amorphous materials. This includes nucleus growth, spinoidal decomposition, and nuclei agglomeration and coarsening. Various types of glass are analyzed.

  9. Development of the Two Phase Flow Separator Experiment for a Reduced Gravity Aircraft Flight

    NASA Technical Reports Server (NTRS)

    Golliher, Eric; Gotti, Daniel; Owens, Jay; Gilkey, Kelly; Pham, Nang; Stehno, Philip

    2016-01-01

    The recent hardware development and testing of a reduced gravity aircraft flight experiment has provided valuable insights for the future design of the Two Phase Flow Separator Experiment (TPFSE). The TPFSE is scheduled to fly within the Fluids Integration Rack (FIR) aboard the International Space Station (ISS) in 2020. The TPFSE studies the operational limits of gas and liquid separation of passive cyclonic separators. A passive cyclonic separator utilizes only the inertia of the incoming flow to accomplish the liquid-gas separation. Efficient phase separation is critical for environmental control and life support systems, such as recovery of clean water from bioreactors, for long duration human spaceflight missions. The final low gravity aircraft flight took place in December 2015 aboard NASA's C9 airplane.

  10. Series Expansions for Frustrated Quantum Ising Magnets

    NASA Astrophysics Data System (ADS)

    Gelfand, M. P.; Priour, D. J.; Sondhi, S. L.

    2000-03-01

    We have computed the phase diagram of a frustrated Ising ladder in a transverse field via the Wolff Monte Carlo Cluster algorithm and by Pad'e Analysis of a series for the excitation spectrum about the large transverse field limit. A comparison of the two methods suggests that analysis of the perturbation series is a viable method for obtaining the phase diagrams of such systems even in cases, such as this one , where there is no phase transition down to arbitrarily small values of the transverse field. We will also discuss the application of the series technique to two dimensional systems of greater experimental interest, such as on the Kagome lattice which is also believed to realize a cooperative paramagnet at small transverse fields.

  11. Smoothed particle hydrodynamics model for phase separating fluid mixtures. II. Diffusion in a binary mixture.

    PubMed

    Thieulot, Cedric; Janssen, L P B M; Español, Pep

    2005-07-01

    A previously formulated smoothed particle hydrodynamics model for a phase separating mixture is tested for the case when viscous processes are negligible and only mass and energy diffusive processes take place. We restrict ourselves to the case of a binary mixture that can exhibit liquid-liquid phase separation. The thermodynamic consistency of the model is assessed and the potential of the model to study complex pattern formation in the presence of various thermal boundaries is illustrated.

  12. Phase Separation of Binary Charged Particle Systems with Small Size Disparities using a Dusty Plasma.

    PubMed

    Killer, Carsten; Bockwoldt, Tim; Schütt, Stefan; Himpel, Michael; Melzer, André; Piel, Alexander

    2016-03-18

    The phase separation in binary mixtures of charged particles has been investigated in a dusty plasma under microgravity on parabolic flights. A method based on the use of fluorescent dust particles was developed that allows us to distinguish between particles of slightly different size. A clear trend towards phase separation even for smallest size (charge) disparities is observed. The diffusion flux is directly measured from the experiment and uphill diffusion coefficients have been determined.

  13. Kinetic model of phase separation in binary mixtures with hard mobile impurities.

    PubMed

    Ginzburg, V V; Peng, G; Qiu, F; Jasnow, D; Balazs, A C

    1999-10-01

    We develop a mean-field rate-equation model for the kinetics of phase separation in binary mixtures with hard mobile impurities. For impurities preferentially wet by one of the components, the phase separation is arrested in the late stage. The "steady-state" domain size depends strongly on both the particle diffusion constant and the particle concentration. We compare theoretical results with the simulation data and find good qualitative agreement.

  14. Use of Solid Phase Extraction in the Biochemistry Laboratory to Separate Different Lipids

    ERIC Educational Resources Information Center

    Flurkey, William H.

    2005-01-01

    Solid-phase extraction (SPE) was used to demonstrate how various lipids and lipid classes could be separated in a biochemistry laboratory setting. Three different SPE methods were chosen on their ability to separate a lipid mixture, consisting of a combination of a either a fatty acid, a triacylglycerol, a mono- or diacylglycerol, phospholipid,…

  15. Fabrication of Janus droplets by evaporation driven liquid-liquid phase separation.

    PubMed

    Zhang, Qingquan; Xu, Meng; Liu, Xiaojun; Zhao, Wenfeng; Zong, Chenghua; Yu, Yang; Wang, Qi; Gai, Hongwei

    2016-04-11

    We present a universal and scalable method to fabricate Janus droplets based on evaporation driven liquid-liquid phase separation. In this work, the morphologies and chemical properties of separate parts of the Janus droplets can be flexibly regulated, and more complex Janus droplets (such as core-shell Janus droplets, ternary Janus droplets, and multiple Janus droplets) can be constructed easily.

  16. Deliberate exotic magnetism via frustration and topology

    NASA Astrophysics Data System (ADS)

    Nisoli, Cristiano; Kapaklis, Vassilios; Schiffer, Peter

    2017-03-01

    Introduced originally to mimic the unusual, frustrated behaviour of spin ice pyrochlores, artificial spin ice can be realized in odd, dedicated geometries that open the door to new manifestations of a higher level of frustration.

  17. Study of Frustrative Nonreward in Children

    ERIC Educational Resources Information Center

    Kroes, William H.

    1973-01-01

    It was hypothesized that an enhancement of goal objects would occur for children who were frustrated from receiving these goal objects. Three dependent measures were used to measure the frustration effects: size estimation, verbal evaluation, and selective attention. (Author)

  18. Geometrically Frustrated Magnets as Model Systems

    DTIC Science & Technology

    2007-11-02

    and a kagome lattice of corner sharing triangles. In both of these systems we are examining the evolution of frustration as a function of dilution of the frustrated lattice with non-magnetic impurities.

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

    NASA Astrophysics Data System (ADS)

    Takagi, Youhei; Okamoto, Sachiya

    2015-11-01

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

  20. Phase separation induced molecular fractionation of gum arabic--sugar beet pectin systems.

    PubMed

    Mao, Peng; Zhao, Meng; Zhang, Fan; Fang, Yapeng; Phillips, Glyn O; Nishinari, Katsuyoshi; Jiang, Fatang

    2013-10-15

    This paper investigates the phase separation and phase separation-induced fractionation of gum arabic (GA)/sugar beet pectin (SBP) mixed solutions. A phase diagram, including cloud and binodal curves, was established by visual observation and phase composition analysis. The deviation of the binodal curve from the cloud curve was a result of phase separation-induced fractionation of polydisperse GA and SBP molecules. Fractionation of GA increased the content of arabinogalactan-protein complex (AGP) from ca. 13% to 27%. The fractionated GA (FGA) showed improved emulsifying functionality, whereas the fractionated SBP (FSBP) had a reduced emulsifying functionality. The changes in emulsifying efficiency can be explained by interfacial adsorption behaviors at the oil-water interface as indicated by interfacial tension measurements.

  1. Images reveal that atmospheric particles can undergo liquid-liquid phase separations

    NASA Astrophysics Data System (ADS)

    Bertram, A. K.; You, Y.; Renbaum-Wolff, L.; Carreras-Sospedra, M.; Hiranuma, N.; Smith, M.; Zhang, X.; Weber, R.; Shilling, J. E.; Dabdub, D.; Martin, S. T.

    2012-12-01

    A large fraction of submicron atmospheric particles contain both organic material and inorganic salts. As the relative humidity cycles in the atmosphere, these mixed particles can undergo a range of phase transitions, possibly including liquid-liquid phase separation. If liquid-liquid phase separation occurs, the gas-particle partitioning of atmospheric semi-volatile organic compounds, the scattering and absorption of solar radiation, and the uptake of reactive gas species on atmospheric particles may be affected. Here, using optical and fluorescence microscopy, we present images that show the coexistence of two non-crystalline phases in particles generated from samples collected on multiple days in Atlanta, Georgia, and in particles generated in the laboratory using simulated atmospheric conditions. These results show that atmospheric particles can undergo liquid-liquid phase separations.

  2. Dynamics of disordered and frustrated magnets

    NASA Astrophysics Data System (ADS)

    Woo, Na Yoon

    Gd3Ga5O12 (GGG) is an insulating Heisenberg antiferromagnet. It is highly frustrated owing to its garnet structure, which is composed of elementary triangles with dominant antiferromagnetic interactions. We studied the effect of disorder in this geometrically frustrated system by changing the level of disorder in GGG:Ndx with x ranging from 0 to 1%. We measured the AC magnetic susceptibility in both the linear and nonlinear regimes and characterized the low temperature phases. As a result, we observed signatures of short range order in the 0% and 0.1% crystals, but not in the 1% sample, indicating that the order is suppressed in the 1% sample because of increasing frustration. The Nd doping compensates for the Gd-Ga off stoichiometry and pushes the system to a more perfectly frustrated state. We used the non-linear response to characterize the evolution of isolated spin clusters as a function of x. The Nd doping effectively relieves the net disorder. Hence the sample with the highest doping presents the smallest net correlated moments and the smallest onset field to activate the clusters from the background spin bath. The second project we report addresses the nonequilibrium dynamics of two related spin glasses. The model systems are the Ising magnets LiHo xY1--xF4 with x = 0.167 and 0.198. Although both systems undergo spin glass transitions, the mechanism that drives the phase transition is known to be different. The diluted sample is more affected by entanglement and in the concentrated system, the random field plays a more important role. In this thesis, we performed preliminary thermal and quantum aging experiments to compare the two systems. In the classical aging measurement, with temperature as the pertinent variable, the decay is exponential and measures primarily the response of the lattice. However quantum aging measurements using transverse field probe the spin relaxation character. The x = 0.167 and 0.198 crystals decay in opposite directions

  3. Frustrated Ising model on the Cairo pentagonal lattice.

    PubMed

    Rojas, M; Rojas, Onofre; de Souza, S M

    2012-11-01

    Through the direct decoration transformation approach, we obtain a general solution for the pentagonal Ising model, showing its equivalence to the isotropic free-fermion eight-vertex model. We study the ground-state phase diagram, in which one ferromagnetic (FM) state, one ferrimagnetic (FIM) state, and one frustrated state are found. Using the exact solution of the pentagonal Ising model, we discuss the finite-temperature phase diagrams and find a phase transition between the FIM state and the disordered state as well as a phase transition between the disordered state and the FM state. We also discuss some additional remarkable properties of the model, such as the magnetization, entropy, and specific heat, at finite temperature and at its low-temperature asymptotic limit. Because of the influence of the second-order phase transition between the frustrated and ferromagnetic phases, we obtain surprisingly low values of the entropy and the specific heat until the critical temperature is reached.

  4. Phase separation of cesium from lead borosilicate glass by heat treatment under a reducing atmosphere.

    PubMed

    Xu, Zhanglian; Okada, Takashi; Nishimura, Fumihiro; Yonezawa, Susumu

    2016-11-05

    A phase-separation technique for removing sodium from glass using a heat-treatment method under a reducing atmosphere was previously developed for sodium recovery from waste glass. In this study, this technique was applied to cesium-containing lead borosilicate glass to concentrate the cesium in phase-separated sodium-rich materials for efficient cesium extraction. The theoretical phase-separation temperature of the sodium-rich phase was simulated by thermodynamic equilibrium calculations and was predicted to occur below 700°C for lead borosilicate glass. Experimentally, a simulated lead borosilicate glass was melted at 1000°C and subsequently annealed below 700°C under a CO-containing reducing atmosphere. The phase separation of cesium was found to occur with sodium enrichment on the glass surface that was in contact with the gas phase, promoting cesium extraction from the treated glass using water. The cesium extraction efficiency was affected by the surface area of the treated glass that was in contact with water, and under the examined conditions, the cesium extraction efficiency was up to 66%. Phase separation using reductive heat treatment, combined with a water leaching technique, is suggested to be effective for extracting cesium incorporated in borosilicate glass waste.

  5. Enantiomeric separation of biaryl atropisomers using cyclofructan based chiral stationary phases.

    PubMed

    Woods, Ross M; Patel, Darshan C; Lim, Yeeun; Breitbach, Zachary S; Gao, Hongyin; Keene, Craig; Li, Gongqiang; Kürti, László; Armstrong, Daniel W

    2014-08-29

    Normal phase chiral HPLC methods are presented for the enantiomeric separation of 30 biaryl atropisomers including 18 new compounds recently produced via a novel synthetic approach. Three new cyclofructan based chiral stationary phases were evaluated. Separations were achieved for all but six analytes and the LARIHC™ CF6-P alone provided 15 baseline separations. Effects of polar modifiers and temperature effects also were studied. Apparent thermodynamic parameters were determined by van't Hoff plots. Preparative scale methods were developed and employed resulting in the first ever isolation of these novel atropisomers in their pure enantiomeric form. Insights into the mechanism of retention and chiral discrimination are presented.

  6. Enantiomeric Separation of Biaryl Atropisomers Using Cyclofructan Based Chiral Stationary Phases

    PubMed Central

    Woods, Ross M.; Patel, Darshan C.; Lim, Yeeun; Breitbach, Zachary S.; Gao, Hongyin; Keene, Craig; Li, Gongqiang; Kürti, László

    2014-01-01

    Normal phase chiral HPLC methods are presented for the enantiomeric separation of 30 biaryl atropisomers including 18 new compounds recently produced via a novel synthetic approach. Three new cyclofructan based chiral stationary phases were evaluated. Separations were achieved for all but six analytes and the LARIHC™ CF6-P alone provided 15 baseline separations. Effects of polar modifiers and temperature effects also were studied. Apparent thermodynamic parameters were determined by van't Hoff plots. Preparative scale methods were developed and employed resulting in the first ever isolation of these novel atropisomers in their pure enantiomeric form. Insights into the mechanism of retention and chiral discrimination are presented. PMID:24835594

  7. The Two-Phase Flow Separator Experiment Breadboard Model: Reduced Gravity Aircraft Results

    NASA Technical Reports Server (NTRS)

    Rame, E; Sharp, L. M.; Chahine, G.; Kamotani, Y.; Gotti, D.; Owens, J.; Gilkey, K.; Pham, N.

    2015-01-01

    Life support systems in space depend on the ability to effectively separate gas from liquid. Passive cyclonic phase separators use the centripetal acceleration of a rotating gas-liquid mixture to carry out phase separation. The gas migrates to the center, while gas-free liquid may be withdrawn from one of the end plates. We have designed, constructed and tested a breadboard that accommodates the test sections of two independent principal investigators and satisfies their respective requirements, including flow rates, pressure and video diagnostics. The breadboard was flown in the NASA low-gravity airplane in order to test the system performance and design under reduced gravity conditions.

  8. Effect of confinement and kinetics on the morphology of phase separating gelatin-maltodextrin droplets.

    PubMed

    Fransson, Sophia; Lorén, Niklas; Altskär, Annika; Hermansson, Anne-Marie

    2009-06-08

    The effect of confinement on the structure evolution and final morphology during phase separation and gelation of gelatin and maltodextrin was investigated and compared to the structures seen in bulk phase. Emulsion droplets with diameters from 4 to 300 mum were analyzed using confocal laser scanning microscopy and image analysis. With the confocal laser scanning microscope it was possible to follow the entire phase separating process inside the droplets in real-time. The samples were either quenched directly from 70 degrees C down to 20 degrees C or exposed to holding times at 40 degrees C. Different cooling procedures were studied to examine the structure evolution both before and after gelation in the restricted geometries. The concentration of the biopolymer mixture was kept constant at 4 w/w% gelatin and 6 w/w% maltodextrin. The results revealed that the size of the confinement had a great effect on both the initiation of phase separation and the final morphology of the microstructure inside the emulsion droplets. The phase separation in small droplets was observed to occur at a temperature above the phase separating temperature for bulk. Small droplets had either a microstructure with a shell of maltodextrin and core of gelatin or a microstructure where the two biopolymers had formed two separate bicontinuous halves. The initiation of phase separation in large droplets was similar to what was seen in bulk. The microstructure in large droplets was discontinuous, resembling the morphology in bulk phase. The kinetics had an effect on the character of the maltodextrin inclusions, as the cooling procedure of a direct quench gave spherical inclusions with an even size distribution, while a holding time at 40 degrees C resulted in asymmetrical and elongated inclusions.

  9. Extent and mechanism of phase separation during the extrusion of calcium phosphate pastes.

    PubMed

    O'Neill, Rory; McCarthy, Helen O; Cunningham, Eoin; Montufar, Edgar; Ginebra, Maria-Pau; Wilson, D Ian; Lennon, Alex; Dunne, Nicholas

    2016-02-01

    The aim of this study was to increase understanding of the mechanism and dominant drivers influencing phase separation during ram extrusion of calcium phosphate (CaP) paste for orthopaedic applications. The liquid content of extrudate was determined, and the flow of liquid and powder phases within the syringe barrel during extrusion were observed, subject to various extrusion parameters. Increasing the initial liquid-to-powder mass ratio, LPR, (0.4-0.45), plunger rate (5-20 mm/min), and tapering the barrel exit (45°-90°) significantly reduced the extent of phase separation. Phase separation values ranged from (6.22 ± 0.69 to 18.94 ± 0.69 %). However altering needle geometry had no significant effect on phase separation. From powder tracing and liquid content determination, static zones of powder and a non-uniform liquid distribution was observed within the barrel. Measurements of extrudate and paste LPR within the barrel indicated that extrudate LPR remained constant during extrusion, while LPR of paste within the barrel decreased steadily. These observations indicate the mechanism of phase separation was located within the syringe barrel. Therefore phase separation can be attributed to either; (1) the liquid being forced downstream by an increase in pore pressure as a result of powder consolidation due to the pressure exerted by the plunger or (2) the liquid being drawn from paste within the barrel, due to suction, driven by dilation of the solids matrix at the barrel exit. Differentiating between these two mechanisms is difficult; however results obtained suggest that suction is the dominant phase separation mechanism occurring during extrusion of CaP paste.

  10. Polymerization- and solvent-induced phase separation in hydrophilic-rich dentin adhesive mimic.

    PubMed

    Abedin, Farhana; Ye, Qiang; Good, Holly J; Parthasarathy, Ranganathan; Spencer, Paulette

    2014-07-01

    Current dental resin undergoes phase separation into hydrophobic-rich and hydrophilic-rich phases during infiltration of the over-wet demineralized collagen matrix. Such phase separation undermines the integrity and durability of the bond at the composite/tooth interface. This study marks the first time that the polymerization kinetics of model hydrophilic-rich phase of dental adhesive has been determined. Samples were prepared by adding varying water content to neat resins made from 95 and 99 wt.% hydroxyethylmethacrylate and 5 and 1 wt.% (2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl1]-propane prior to light curing. Viscosity of the formulations decreased with increased water content. The photopolymerization kinetics study was carried out with a time-resolved Fourier transform infrared spectrometer. All of the samples exhibited two-stage polymerization behavior which has not been reported previously for dental resin formulation. The lowest secondary rate maxima were observed for water contents of 10-30 wt.%. Differential scanning calorimetry (DSC) showed two glass transition temperatures for the hydrophilic-rich phase of dental adhesive. The DSC results indicate that the heterogeneity within the final polymer structure decreased with increasing water content. The results suggest a reaction mechanism involving both polymerization-induced phase separation and solvent-induced phase separation for the model hydrophilic-rich phase of dental resin.

  11. Development of phase-separated scintillators with light-guiding properties.

    PubMed

    Yasui, Nobuhiro; Ohashi, Yoshihiro; Kobayashi, Tamaki; Den, Tohru

    2012-10-23

    Alkali halide systems that function as phase-separated scintillators (PSSs) with light-guiding properties are sucessfully created. Furthermore, it is the matrix phases of the PSSs which display the light-guiding properties. CsI-NaCl:Tl is a practical material pair because of its high pixel light output and good spatial resolution.

  12. Phase separation in the two-dimensional bosonic Hubbard model with ring exchange.

    PubMed

    Rousseau, V; Batrouni, G G; Scalettar, R T

    2004-09-10

    We show that soft-core bosons in two dimensions with a ring exchange term exhibit a tendency for phase separation. This observation suggests that the thermodynamic stability of normal Bose liquid phases driven by ring exchange should be carefully examined.

  13. Frustration of dissipation in a spin-boson model

    NASA Astrophysics Data System (ADS)

    Ingersent, Kevin; Duru, Alper

    2009-03-01

    The spin-boson model (SBM), in which a quantum two-level system couples via one component of its effective spin to a dissipative bosonic bath, has many realizations. There has been much recent interest in the SBM with a sub-Ohmic bath characterized by a power-law spectral exponent 0 < s < 1, where at zero temperature a quantum critical point separates delocalized and localized phases. Numerical renormalization group calculations have called into question [1] the validity of the long-assumed mapping between the SBM and the classical Ising chain with interactions decaying with distance |i-j| as 1/|i-j|^1+s. Attention has also fallen on a variant of the SBM in which two components of the impurity spin couple to different bosonic baths. For Ohmic case (s = 1), competition between the baths has been shown to frustrate the dissipation and reduce the coupling of the impurity to the environment [2]. The present study addresses the SBM with two sub-Ohmic baths, where dissipative effects are intrinsically stronger than for s=1. Numerical renormalization group methods are used to identify a continuous quantum phase transition in this model and to evaluate critical exponents characterizing the quantum-critical behavior in the vicinity of the transition. [1] M. Vojta et al., Phys. Rev. Lett. 94, 070604 (2005). [2] E. Novais et al., Phys. Rev. B 72, 014417 (2005). Supported by NSF Grant DMR-0710540.

  14. Topological triple-vortex lattice stabilized by mixed frustration in expanded honeycomb Kitaev-Heisenberg model

    PubMed Central

    Yao, Xiaoyan; Dong, Shuai

    2016-01-01

    The expanded classical Kitaev-Heisenberg model on a honeycomb lattice is investigated with the next-nearest-neighboring Heisenberg interaction considered. The simulation shows a rich phase diagram with periodic behavior in a wide parameter range. Beside the double 120° ordered phase, an inhomogeneous phase is uncovered to exhibit a topological triple-vortex lattice, corresponding to the hexagonal domain structure of vector chirality, which is stabilized by the mixed frustration of two sources: the geometrical frustration arising from the lattice structure as well as the frustration from the Kitaev couplings. PMID:27229486

  15. Double-antibody solid-phase radioimmunoassay: a simplified phase-separation procedure applied to various ligands

    SciTech Connect

    Tevaarwerk, G.J.M.; Boyle, D.A.; Hurst, C.J.; Anguish, I.; Uksik, P.

    1980-06-01

    The purpose was to develop a simplified and reliable method of separating free from antibody-bound ligand using a precipitating antibody linked to a cellulose derivative. Dose-response curves and control sera were set up in parallel for various pituitary and placental polypeptides, steroid hormones, insulin, glucagon, triiodothyronine, thyroxine, angiotensin I, calcitonin, gastrin, cyclic AMP, and digoxin. After first-antibody reactions had reached equilibrium, free and bound ligand were separated using a double-antibody solid-phase system in parallel with conventional methods, including dextran-coated charcoal, double-antibody precipitation, single-antibody solid phase, organic solvents, salt precipitation, and anion-exchange resins. The effect of variations in temperature, incubation time, protein content, pH, and amount of separating material added were studied. The results showed that separation was complete within 1 hr for small ligand molecules and within 2 hr for larger ones. Dose-response curves and control-sera results closely paralleled those obtained with conventional methods. The method was not affected by moderate variations in incubation variables. Nonspecific binding was less than 3% in all assays, while intra-assay and interassay coefficients of variation were similar to those obtained with conventional phase-separation methods. It is concluded that the method is a simple and rapid alternative phase-separation system. It has the advantage of being free from common nonspecific intersample variations, and can be applied to any assay system based on rabbit or guinea pig antibodies without preliminay time- or reagent-consuming titration or adjustments to establish optimum phase-separating conditions.

  16. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy

    PubMed Central

    Wang, W .L.; Wu, Y. H.; Li, L. H.; Zhai, W.; Zhang, X. M.; Wei, B.

    2015-01-01

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate. PMID:26552711

  17. Liquid-liquid phase separation of freely falling undercooled ternary Fe-Cu-Sn alloy.

    PubMed

    Wang, W L; Wu, Y H; Li, L H; Zhai, W; Zhang, X M; Wei, B

    2015-11-10

    The active modulation and control of the liquid phase separation for high-temperature metallic systems are still challenging the development of advanced immiscible alloys. Here we present an attempt to manipulate the dynamic process of liquid-liquid phase separation for ternary Fe47.5Cu47.5Sn5 alloy. It was firstly dispersed into numerous droplets with 66 ~ 810 μm diameters and then highly undercooled and rapidly solidified under the containerless microgravity condition inside drop tube. 3-D phase field simulation was performed to explore the kinetic evolution of liquid phase separation. Through regulating the combined effects of undercooling level, phase separation time and Marangoni migration, three types of separation patterns were yielded: monotectic cell, core shell and dispersive structures. The two-layer core-shell morphology proved to be the most stable separation configuration owing to its lowest chemical potential. Whereas the monotectic cell and dispersive microstructures were both thermodynamically metastable transition states because of their highly active energy. The Sn solute partition profiles of Fe-rich core and Cu-rich shell in core-shell structures varied only slightly with cooling rate.

  18. Hierarchical multiscale hyperporous block copolymer membranes via tunable dual-phase separation

    PubMed Central

    Yoo, Seungmin; Kim, Jung-Hwan; Shin, Myoungsoo; Park, Hyungmin; Kim, Jeong-Hoon; Lee, Sang-Young; Park, Soojin

    2015-01-01

    The rational design and realization of revolutionary porous structures have been long-standing challenges in membrane science. We demonstrate a new class of amphiphilic polystyrene-block-poly(4-vinylpyridine) block copolymer (BCP)–based porous membranes featuring hierarchical multiscale hyperporous structures. The introduction of surface energy–modifying agents and the control of major phase separation parameters (such as nonsolvent polarity and solvent drying time) enable tunable dual-phase separation of BCPs, eventually leading to macro/nanoscale porous structures and chemical functionalities far beyond those accessible with conventional approaches. Application of this BCP membrane to a lithium-ion battery separator affords exceptional improvement in electrochemical performance. The dual-phase separation–driven macro/nanopore construction strategy, owing to its simplicity and tunability, is expected to be readily applicable to a rich variety of membrane fields including molecular separation, water purification, and energy-related devices. PMID:26601212

  19. Phase-separation perspective on dynamic heterogeneities in glass-forming liquids.

    PubMed

    Cammarota, C; Cavagna, A; Giardina, I; Gradenigo, G; Grigera, T S; Parisi, G; Verrocchio, P

    2010-07-30

    We study dynamic heterogeneities in a model glass former whose overlap with a reference configuration is constrained to a fixed value. We find that the system phase separates into regions of small and large overlap, indicating that a nonzero surface tension plays an important role in the formation of dynamical heterogeneities. We calculate an appropriate thermodynamic potential and find evidence of a Maxwell construction consistent with a spinodal decomposition of two phases. Our results suggest that even in standard, unconstrained systems dynamic heterogeneities are the expression of an ephemeral phase-separating regime ruled by a finite surface tension.

  20. Laser-induced separation of hydrogen isotopes in the liquid phase

    DOEpatents

    Freund, Samuel M.; Maier, II, William B.; Beattie, Willard H.; Holland, Redus F.

    1980-01-01

    Hydrogen isotope separation is achieved by either (a) dissolving a hydrogen-bearing feedstock compound in a liquid solvent, or (b) liquefying a hydrogen-bearing feedstock compound, the liquid phase thus resulting being kept at a temperature at which spectral features of the feedstock relating to a particular hydrogen isotope are resolved, i.e., a clear-cut isotope shift is delineated, irradiating the liquid phase with monochromatic radiation of a wavelength which at least preferentially excites those molecules of the feedstock containing a first hydrogen isotope, inducing photochemical reaction in the excited molecules, and separating the reaction product containing the first isotope from the liquid phase.

  1. Structure and Phase Separation in Ultrathin Ag/Cu Amorphous Alloy System

    NASA Astrophysics Data System (ADS)

    Chen, Hao

    2005-03-01

    The structure of disordered metallic alloys is an important but unsolved problem. Previous studies on Ag-Cu system showed that relatively homogeneous solid solutions formed at liquid nitrogen temperature decompose into separate phases or evolve into crystalline structure at a higher temperature. In this research project, we prepared ultra-thin Ag-Cu films on amorphous carbon support by HV magnetron sputtering with both targets. With high energy Ag and Cu atoms bombarding on the carbon substrate, they are forced to form amorphous alloy or nano-crystalline thin film at room temperature. We have investigated the structure of ultra-thin Ag-Cu films by examining their pair distribution function (PDF) using electron diffraction and observed phase separation process directly in STEM images. In the STEM Z-contrast images, since the contrast is directly related to the atomic number (Z) of the components, we can see clearly the phase separation process. Experimental results show that the sample morphology evolutions are different in samples with different thickness, and the phase separation depends on various Ag/Cu atomic ratios. In Ag50Cu50 sample, early stage phase separation is associated with increasing Cu crystallite size, indicates that Cu diffuse out of Ag-Cu solid solution phase.

  2. Chiral separation of novel diazenes on a polysaccharide-based stationary phase in the reversed-phase mode.

    PubMed

    Vojtylová, Terézia; Hamplová, Věra; Galewski, Zbigniew; Korbecka, Izabela; Sýkora, David

    2017-01-31

    Chiral high-performance liquid chromatography separation of two recently synthesized liquid crystalline materials C1 and C2 was studied in the reversed-phase mode. Both materials have an azo-moiety and one chiral centre in their molecular structures. They were available in racemic and pure S forms. For the enantiomeric separations, a Chiralpak AY-RH stationary phase based on amylose tris(5-chloro-2-methylphenylcarbamate) coated on 5 μm silica was used. The compounds were analyzed in both of their possible forms, the more thermodynamically stable E form and the labile Z form. The conditions and time scale of the UV-induced E to Z transition were briefly evaluated. Under the optimized conditions, we were able to baseline separate S and R enantiomers of both of the studied materials not only in their E forms but also in their Z forms. In comparison to the separation in the normal-phase mode, which we have reported recently, the resolution in the reversed-phase mode is significantly better. Interestingly, peak reversal was noticed for the S and R enantiomers when the separation was carried out with E versus Z forms of both compounds. This article is protected by copyright. All rights reserved.

  3. Precipitation phase separation schemes in the Naqu River basin, eastern Tibetan plateau

    NASA Astrophysics Data System (ADS)

    Liu, Shaohua; Yan, Denghua; Qin, Tianling; Weng, Baisha; Lu, Yajing; Dong, Guoqiang; Gong, Boya

    2016-11-01

    Precipitation phase has a profound influence on the hydrological processes in the Naqu River basin, eastern Tibetan plateau. However, there are only six meteorological stations with precipitation phase (rainfall/snowfall/sleet) before 1979 within and around the basin. In order to separate snowfall from precipitation, a new separation scheme with S-shaped curve of snowfall proportion as an exponential function of daily mean temperature was developed. The determinations of critical temperatures in the single/two temperature threshold (STT/TTT2) methods were explored accordingly, and the temperature corresponding to the 50 % snowfall proportion (SP50 temperature) is an efficiently critical temperature for the STT, and two critical temperatures in TTT2 can be determined based on the exponential function and SP50 temperature. Then, different separation schemes were evaluated in separating snowfall from precipitation in the Naqu River basin. The results show that the S-shaped curve methods outperform other separation schemes. Although the STT and TTT2 slightly underestimate and overestimate the snowfall when the temperature is higher and colder than SP50 temperature respectively, the monthly and annual separation snowfalls are generally consistent with the observed snowfalls. On the whole, S-shaped curve methods, STT, and TTT2 perform well in separating snowfall from precipitation with the Pearson correlation coefficient of annual separation snowfall above 0.8 and provide possible approaches to separate the snowfall from precipitation for hydrological modelling.

  4. Lower critical solution temperature (LCST) phase separation of glycol ethers for forward osmotic control.

    PubMed

    Nakayama, Daichi; Mok, Yeongbong; Noh, Minwoo; Park, Jeongseon; Kang, Sunyoung; Lee, Yan

    2014-03-21

    Lower critical solution temperature (LCST) phase transition of glycol ether (GE)-water mixtures induces an abrupt change in osmotic pressure driven by a mild temperature change. The temperature-controlled osmotic change was applied for the forward osmosis (FO) desalination. Among three GEs evaluated, di(ethylene glycol) n-hexyl ether (DEH) was selected as a potential FO draw solute. A DEH-water mixture with a high osmotic pressure could draw fresh water from a high-salt feed solution such as seawater through a semipermeable membrane at around 10 °C. The water-drawn DEH-water mixture was phase-separated into a water-rich phase and a DEH-rich phase at around 30 °C. The water-rich phase with a much reduced osmotic pressure released water into a low-salt solution, and the DEH-rich phase was recovered into the initial DEH-water mixture. The phase separation behaviour, the residual GE concentration in the water-rich phase, the osmotic pressure of the DEH-water mixture, and the osmotic flux between the DEH-water mixture and salt solutions were carefully analysed for FO desalination. The liquid-liquid phase separation of the GE-water mixture driven by the mild temperature change between 10 °C and 30 °C is very attractive for the development of an ideal draw solute for future practical FO desalination.

  5. Hydrogen isotope systematics of phase separation in submarine hydrothermal systems: Experimental calibration and theoretical models

    USGS Publications Warehouse

    Berndt, M.E.; Seal, R.R.; Shanks, Wayne C.; Seyfried, W.E.

    1996-01-01

    Hydrogen isotope fractionation factors were measured for coexisting brines and vapors formed by phase separation of NaCl/H2O fluids at temperatures ranging from 399-450??C and pressures from 277-397 bars. It was found that brines are depleted in D compared to coexisting vapors at all conditions studied. The magnitude of hydrogen isotope fractionation is dependent on the relative amounts of Cl in the two phases and can be empirically correlated to pressure using the following relationship: 1000 ln ??(vap-brine) = 2.54(??0.83) + 2.87(??0.69) x log (??P), where ??(vap-brine) is the fractionation factor and ??P is a pressure term representing distance from the critical curve in the NaCl/H2O system. The effect of phase separation on hydrogen isotope distribution in subseafloor hydrothermal systems depends on a number of factors, including whether phase separation is induced by heating at depth or by decompression of hydrothermal fluids ascending to the seafloor. Phase separation in most subseafloor systems appears to be a simple process driven by heating of seawater to conditions within the two-phase region, followed by segregation and entrainment of brine or vapor into a seawater dominated system. Resulting vent fluids exhibit large ranges in Cl concentration with no measurable effect on ??D. Possible exceptions to this include hydrothermal fluids venting at Axial and 9??N on the East Pacific Rise. High ??D values of low Cl fluids venting at Axial are consistent with phase separation taking place at relatively shallow levels in the oceanic crust while negative ??D values in some low Cl fluids venting at 9??N suggest involvement of a magmatic fluid component or phase separation of D-depleted brines derived during previous hydrothermal activity.

  6. Characterization of fish gelatin-gum arabic complex coacervates as influenced by phase separation temperature.

    PubMed

    Anvari, Mohammad; Pan, Cheol-Ho; Yoon, Won-Byong; Chung, Donghwa

    2015-08-01

    The rheological and structural characteristics of fish gelatin (FG)-gum arabic (GA) complex coacervate phase, separated from an aqueous mixture of 1% FG and 1% GA at pH 3.5, were investigated as influenced by phase separation temperature. Decreasing the phase separation temperature from 40 to 10 °C lead to: (1) the formation of a coacervate phase with a larger volume fraction and higher biopolymer concentrations, which is more viscous, more structural resistant at low shear rates, more shear-thinning at high shear rates, and more condensed in microstructure, (2) a solid-like elastic behavior of the phase separated at 10 °C at a high oscillatory frequency, (3) the increase in gelling and melting temperatures of the coacervate phase (3.7-3.9 °C and 6.2-6.9 °C, respectively), (4) the formation of a more rigid and thermo-stable coacervate gel. The coacervate phase is regarded as a homogeneously networked biopolymer matrix dispersed with water vacuoles and its gel as a weak physical gel reinforced by FG-GA attractive electrostatic interactions.

  7. Evaluation of the Sensitivity of Two-Phase Flow Model for the Steam Separator Analysis

    SciTech Connect

    Michio Murase; Masao Chaki

    2006-07-01

    Reducing of the pressure losses of steam separator systems of boiling water reactor (BWR) plants is useful to reduce the required pump head and enhance core stability design margin. The need to reduce the pressure losses of steam separator systems is especially important in BWR plants that have high power density cores and natural circulation systems. The core flow rate of a BWR plant with a natural circulation system is affected by the pressure losses of steam separator systems. In BWR plants with high power density cores, the core stability design margin is affected by these pressure losses. Generally, reducing the pressure losses of the steam separator systems leads to increased carry-under and carryover. Reducing the pressure losses while keeping the characteristics of both carry-under and carryover is desired, so many studies have been done. The steam separator of a BWR plant consists of a standpipe section, a swirl vane section and three-barrel sections. Two-phase flow of steam and water enters the steam separator through the standpipe section and reaches the swirl vane section. In the swirl vane section, the two-phase flow is given centrifugal force and is basically separated into steam and water. Therefore investigating the two-phase flow characteristics of the swirl vane section is very important. After the swirl vane section, the two-phase flow enters the barrel sections. Each barrel has a pick-off ring. The water in the barrel section is mainly removed by these pick-off rings because the water mainly flows upward as a liquid film in the barrel section due to the centrifugal force given in the swirl vane section. We researched the effect of using the drag force model of the swirling two-phase flow in analyzing a steam separator and we found that the drag force model greatly affects the results of the analysis. (authors)

  8. Ternary Phase-Separation Investigation of Sol-Gel Derived Silica from Ethyl Silicate 40.

    PubMed

    Wang, Shengnan; Wang, David K; Smart, Simon; da Costa, João C Diniz

    2015-09-28

    A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H2O/Si ratios. The solution composition within the immiscible region of the ES40 phase-separated system shows that the hydrolysis and condensation reactions decreased with decreasing reaction temperature. A mesoporous structure was obtained at low temperature due to weak drying forces from slow solvent evaporation on one hand and formation of unreacted ES40 cages in the other, which reduced network shrinkage and produced larger pores. This was attributed to the concentration of the reactive sites around the phase-separated interface, which enhanced the condensation and crosslinking. Contrary to dense silica structures obtained from sol-gel reactions in the miscible region, higher microporosity was produced via a phase-separated sol-gel system by using high H2O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, which coupled with stiffening of the network, made it more resistant to compression and densification.

  9. Ternary Phase-Separation Investigation of Sol-Gel Derived Silica from Ethyl Silicate 40

    NASA Astrophysics Data System (ADS)

    Wang, Shengnan; Wang, David K.; Smart, Simon; Diniz da Costa, João C.

    2015-09-01

    A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H2O/Si ratios. The solution composition within the immiscible region of the ES40 phase-separated system shows that the hydrolysis and condensation reactions decreased with decreasing reaction temperature. A mesoporous structure was obtained at low temperature due to weak drying forces from slow solvent evaporation on one hand and formation of unreacted ES40 cages in the other, which reduced network shrinkage and produced larger pores. This was attributed to the concentration of the reactive sites around the phase-separated interface, which enhanced the condensation and crosslinking. Contrary to dense silica structures obtained from sol-gel reactions in the miscible region, higher microporosity was produced via a phase-separated sol-gel system by using high H2O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, which coupled with stiffening of the network, made it more resistant to compression and densification.

  10. Ternary Phase-Separation Investigation of Sol-Gel Derived Silica from Ethyl Silicate 40

    PubMed Central

    Wang, Shengnan; Wang, David K.; Smart, Simon; Diniz da Costa, João C.

    2015-01-01

    A ternary phase-separation investigation of the ethyl silicate 40 (ES40) sol-gel process was conducted using ethanol and water as the solvent and hydrolysing agent, respectively. This oligomeric silica precursor underwent various degrees of phase separation behaviour in solution during the sol-gel reactions as a function of temperature and H2O/Si ratios. The solution composition within the immiscible region of the ES40 phase-separated system shows that the hydrolysis and condensation reactions decreased with decreasing reaction temperature. A mesoporous structure was obtained at low temperature due to weak drying forces from slow solvent evaporation on one hand and formation of unreacted ES40 cages in the other, which reduced network shrinkage and produced larger pores. This was attributed to the concentration of the reactive sites around the phase-separated interface, which enhanced the condensation and crosslinking. Contrary to dense silica structures obtained from sol-gel reactions in the miscible region, higher microporosity was produced via a phase-separated sol-gel system by using high H2O/Si ratios. This tailoring process facilitated further condensation reactions and crosslinking of silica chains, which coupled with stiffening of the network, made it more resistant to compression and densification. PMID:26411484

  11. Movie of phase separation during physics of colloids in space experiment

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area in the video is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

  12. Phase separation during the Experiment on Physics of Colloids in Space

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Still photographs taken over 16 hours on Nov. 13, 2001, on the International Space Station have been condensed into a few seconds to show the de-mixing -- or phase separation -- process studied by the Experiment on Physics of Colloids in Space. Commanded from the ground, dozens of similar tests have been conducted since the experiment arrived on ISS in 2000. The sample is a mix of polymethylmethacrylate (PMMA or acrylic) colloids, polystyrene polymers and solvents. The circular area is 2 cm (0.8 in.) in diameter. The phase separation process occurs spontaneously after the sample is mechanically mixed. The evolving lighter regions are rich in colloid and have the structure of a liquid. The dark regions are poor in colloids and have the structure of a gas. This behavior carnot be observed on Earth because gravity causes the particles to fall out of solution faster than the phase separation can occur. While similar to a gas-liquid phase transition, the growth rate observed in this test is different from any atomic gas-liquid or liquid-liquid phase transition ever measured experimentally. Ultimately, the sample separates into colloid-poor and colloid-rich areas, just as oil and vinegar separate. The fundamental science of de-mixing in this colloid-polymer sample is the same found in the annealing of metal alloys and plastic polymer blends. Improving the understanding of this process may lead to improving processing of these materials on Earth.

  13. Resolving the frustration of fatigue.

    PubMed

    Harpham, W S

    1999-01-01

    Fatigue is a ubiquitous side effect of many cancer therapies. Nevertheless, after treatment is complete, many survivors continue to feel a profound tiredness that affects almost all aspects of life. Even after recovery, patients are often frustrated by their continuing need for extra rest. In this deeply personal, first-person account, a physician relates the various ways that cancer-related fatigue can affect family dynamics, job responsibilities, social interactions, finances, and intimacy. Clinicians can help by searching for treatable medical conditions, but also by taking cancer-related fatigue, and the frustrations it causes, seriously. Patients should be reassured that the fatigue they feel is real, and that by learning personal energy conservation, they should be able to improve their abilities to function, to socialize, to interact with others, and ultimately to adjust to a "new normal" baseline.

  14. Ferromagnetic and antiferromagnetic orders of a phase-separated manganite probed throughout the B -T phase diagram

    NASA Astrophysics Data System (ADS)

    Windsor, Y. W.; Tanaka, Yoshikazu; Scagnoli, V.; Garganourakis, M.; de Souza, R. A.; Medarde, M.; Cheong, S.-W.; Staub, U.

    2016-12-01

    We employ resonant soft x-ray diffraction (RSXD) to isolate the signal from the CE-type antiferromagnetic phase of (La,Pr)1- xC axMn O3 (with x ≈3 /8 ), and follow only this phase through the known phases of the material in the B -T phase diagram. This material is known to exhibit a range of electronic ordering phenomena, most notably a metal-insulator transition (associated with colossal magnetoresistance) and phase separation between the antiferromagnetic phase and a ferromagnetic phase. Bulk magnetization measurements under the same B -T conditions were also conducted, giving a full picture of both phases for direct side-by-side comparison. The comparison specifically focuses on the metal-insulator transition. Upon magnetic field ramping to this transition, we find that the CE-type order undergoes a sharp quench at high temperatures (above phase coexistence temperatures) but that at lower temperatures, where the CE order is metastable, the transition broadens significantly. At the lowest temperatures, where a spin glass-type phase is expected, a slow annihilation of remanent CE domains is observed. Finally, a refined phase diagram is presented.

  15. Separating pairing from quantum phase coherence dynamics above the superconducting transition by femtosecond spectroscopy

    PubMed Central

    Madan, I.; Kurosawa, T.; Toda, Y.; Oda, M.; Mertelj, T.; Kusar, P.; Mihailovic, D.

    2014-01-01

    In classical superconductors an energy gap and phase coherence appear simultaneously with pairing at the transition to the superconducting state. In high-temperature superconductors, the possibility that pairing and phase coherence are distinct and independent processes has led to intense experimental search of their separate manifestations. Using femtosecond spectroscopy methods we now show that it is possible to clearly separate fluctuation dynamics of the superconducting pairing amplitude from the phase relaxation above the critical transition temperature. Empirically establishing a close correspondence between the superfluid density measured by THz spectroscopy and superconducting optical pump-probe response over a wide region of temperature, we find that in differently doped Bi2Sr2CaCu2O8+δ crystals the pairing gap amplitude monotonically extends well beyond Tc, while the phase coherence shows a pronounced power-law divergence as T → Tc, thus showing that phase coherence and gap formation are distinct processes which occur on different timescales. PMID:25014162

  16. The nature of phase separation in a Ru-Sn-O ternary oxide electrocatalyst.

    PubMed

    Wang, Xin; Deng, Fenyong; Tang, Zhongzhi; Wu, Bo; Tang, Dian; Lin, Wei

    2013-03-21

    A phase stability diagram of ruthenium-zirconium oxide (Ru-Sn-O) was constructed by a combination of ab initio density functional theory and thermodynamic calculations. Results suggest that the phase separation/segregation that has been reported in the literature for the RuO(2)-SnO(2) system is through a typical spinodal decomposition mechanism. Ru(0.45)Sn(0.55)O(2) films were prepared by thermal co-decomposition of precursors at 500 °C for varied duration. Quantitative phase analyses of the prepared films based on X-ray diffraction and high-resolution transmission electron microscopy confirmed the spinodal nature of the phase separation. The present fundamental study provides a theoretical guideline for the phase and microstructure design of Ru-Sn-O based mixed oxides for electrocatalysis applications.

  17. Grafted nanoparticles as soft patchy colloids: Self-assembly versus phase separation

    SciTech Connect

    Mahynski, Nathan A.; Panagiotopoulos, Athanassios Z.

    2015-02-21

    We investigate the thermodynamic behavior of a model polymer-grafted nanoparticle (GNP) system on a fine lattice, using grand canonical Monte Carlo simulations, to compare and contrast the validity of two different models for GNPs: “nanoparticle amphiphiles” versus “patchy particles.” In the former model, continuous self-assembly processes are expected to dominate the system, whereas the latter are characterized by first-order phase separation into novel equilibrium phases such as “empty liquids.” We find that, in general, considering GNPs as amphiphiles within the framework of a recent mean-field theory [Pryamtisyn et al., J. Chem. Phys. 131, 221102 (2009)] provides a qualitatively accurate description of the thermodynamics of GNP systems, revealing either first-order phase separation into two isotropic phases or continuous self-assembly. Our model GNPs display no signs of empty liquid formation, suggesting that these nanoparticles do not provide a route to such phases.

  18. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

    SciTech Connect

    Mohan, Ram S.; Shoham, Ovadia

    1999-10-28

    The objective of this five-year project (October, 1997--September, 2002) is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I (1997--2000) will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

  19. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

    SciTech Connect

    Mohan, R.S.; Shoham, O.

    2001-01-18

    The objective of this five-year project (October 1997 - September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997 - 2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000 - 2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

  20. Design and Development of Gas-Liquid Cylindrical Cyclone Compact Separators for Three-Phase Flow

    SciTech Connect

    Mohan, R.S.; Shoham, O.

    2001-01-10

    The objective of this five-year project (October 1997--September 2002) was to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project was executed in two phases. Phase I (1997--2000) focused on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC) Separator. The activities of this phase included the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000--2002), the developed GLCC separator will be tested under high pressure and real crude conditions. This is crucial for validating the GLCC design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP.

  1. D0 Silicon Upgrade: Calc. to Determine Need for a N2 Phase Separator

    SciTech Connect

    Rucinski, Russ; /Fermilab

    1995-04-07

    A nitrogen phase separator is recommended on the liquid supply line at the helium refrigerator plant. This engineering note documents the calculations done to reach that conclusion. The steady state liquid nitrogen consumption rate for the refrigerator, VLPC and solenoid systems is about 30 gal/hr. The estimated heat leak for the piping run to the refrigerator location is 50 watts. The calculated quality at the refrigerator was 0.032. Given this quality, a two phase flow model based on Lockhart-Martinelli and also incorporating Baker diagram nomenclature was run on TK solver. The result of this program was that without the use of a phase separator we could expect a slug flow pattern with a volume fraction of gas of 65%. Based on this, I recommend that we use a phase separator to siphon off the gas before the nitrogen is sent to a standard saver type subcooler. Including the phase separator will help ensure proper operation of the subcooler. The subcooler will help us attempt to deliver single phase liquid to the nitrogen control valves.

  2. Simultaneous separation of hydrophobic and hydrophilic peptides with a silica hydride stationary phase using aqueous normal phase conditions.

    PubMed

    Boysen, Reinhard I; Yang, Yuanzhong; Chowdhury, Jamil; Matyska, Maria T; Pesek, Joseph J; Hearn, Milton T W

    2011-11-04

    The application of a silica hydride modified stationary phase with low organic loading has been investigated as a new type of chromatographic material suitable for the separation and analysis of peptides with electrospray ionization mass spectrometric detection. Retention maps were established to delineate the chromatographic characteristics of a series of peptides with physical properties ranging from strongly hydrophobic to very hydrophilic and encompassing a broad range of pI values (pI 5.5-9.4). The effects of low concentrations of two additives (formic acid and acetic acid) in the mobile phase were also investigated with respect to their contribution to separation selectivity and retention under comparable conditions. Significantly, strong retention of both the hydrophobic and the hydrophilic peptides was observed when high-organic low-aqueous mobile phases were employed, thus providing a new avenue to achieve high resolution peptide separations. For example, simultaneous separation of hydrophobic and hydrophilic peptides was achieved under aqueous normal phase (ANP) chromatographic conditions with linear gradient elution procedures in a single run, whilst further gradient optimization enabled improved peak efficiencies of the more strongly retained hydrophobic and hydrophilic peptides.

  3. Frustrated ferroelectricity in niobate pyrochlores

    NASA Astrophysics Data System (ADS)

    McQueen, T. M.; West, D. V.; Muegge, B.; Huang, Q.; Noble, K.; Zandbergen, H. W.; Cava, R. J.

    2008-06-01

    The crystal structures of the A2B2O7-x niobium based pyrochlores Y2(Nb0.86Y0.14)2O6.91, CaYNb2O7, and Y2NbTiO7 are reported, determined by means of powder neutron diffraction. These compounds represent the first observation of B-site displacements in the pyrochlore structure: the B-site ions are found to be displaced from the ideal pyrochlore positions, creating electric dipoles. The orientations of these dipoles are fully analogous to orientations of the magnetic moments in Ising spin based magnetically frustrated pyrochlores. Diffuse scattering in electron diffraction patterns shows that the displacements are only short range ordered, indicative of geometric frustration of the collective dielectric state of the materials. Comparison to the crystal structure of the Nb5+ (d0) pyrochlore La2ScNbO7 supports the prediction that charge singlets, driven by the tendency of Nb to form metal-metal bonds, are present in these pyrochlores. The observed lack of long range order to these singlets suggests that Nb4+ based pyrochlores represent the dielectric analogy to the geometric frustration of magnetic moments observed in rare earth pyrochlores.

  4. Enantiomeric separations of ruthenium (II) polypyridyl complexes using HPLC with cyclofructan chiral stationary phases.

    PubMed

    Shu, Yang; Breitbach, Zachary S; Dissanayake, Milan K; Perera, Sirantha; Aslan, Joseph M; Alatrash, Nagham; MacDonnell, Frederick M; Armstrong, Daniel W

    2015-01-01

    The enantiomeric separation of 21 ruthenium (II) polypyridyl complexes was achieved with a novel class of cyclofructan-based chiral stationary phases (CSPs) in the polar organic mode. Aromatic derivatives on the chiral selectors proved to be essential for enantioselectivity. The R-napthylethyl carbamate functionalized cyclofructan 6 (LARIHC CF6-RN) column proved to be the most effective overall, while the dimethylphenyl carbamate cyclofructan 7 (LARIHC CF7-DMP) showed complementary selectivity. A combination of acid and base additives was necessary for optimal separations. The retention factor vs. acetonitrile/methanol ratio plot showed a U-shaped retention curve, indicating that different interactions take place at different polar organic solvent compositions. The separation results indicated that π-π interactions, steric effects, and hydrogen bonding contribute to the enantiomeric separation of ruthenium (II) polypyridyl complexes with cyclofructan chiral stationary phases in the polar organic mode.

  5. Viscosity and phase separations of binary CO-He and CO-Ar mixtures

    NASA Astrophysics Data System (ADS)

    Rademacher, N.; Bayarjargal, L.; Morgenroth, W.; Ciezak-Jenkins, J. A.; Winkler, B.

    2015-01-01

    Binary mixtures of 10 and 25 vol% CO in He and 10 vol% CO in Ar have been studied at high pressures and ambient temperature in diamond anvil cells. Phase separations were observed at 5.7(3) GPa, 3.6(2) GPa and 1.6(1) GPa. Earlier studies of ?-He mixtures of comparable concentrations revealed phase separations at significantly larger pressures, while ?-Ar mixtures separate at pressures comparable to those observed in the CO-Ar system here. The viscosity of a CO-rich fluid phase was determined by measuring the velocities of rising He bubbles. After corrections for the influence of the finite container size and of remaining helium in CO, the viscosity of the CO-rich fluid at 3.8(1) GPa was ≈3(1) mPa s, similar to what would be expected for isoelectronic liquid ? under the same conditions.

  6. Phase separation in dilute solutions of 3He in solid 4He

    NASA Astrophysics Data System (ADS)

    Huan, C.; Yin, L.; Xia, J. S.; Candela, D.; Cowan, B. P.; Sullivan, N. S.

    2017-03-01

    We report the results of studies of the phase separation of solid solutions of dilute concentrations of 3He in 4He. The temperatures and the kinetics of the phase separation were determined from NMR experiments for 3He concentrations 1.6 ×10-5phase separation temperatures are found to be in excellent agreement with regular solution theory as augmented by Edwards and Balibar [Phys. Rev. B 39, 4083 (1989), 10.1103/PhysRevB.39.4083]. The growth of 3He droplets shows a t1 /3 time dependence at long times consistent with Ostwald ripening.

  7. Effect of Iron Oxide and Phase Separation on the Color of Blue Jun Ware Glaze.

    PubMed

    Wang, Fen; Yang, Changan; Zhu, Jianfeng; Lin, Ying

    2015-09-01

    Based on the traditional Jun ware glaze, the imitated Jun ware glazes were prepared by adding iron oxide and introducing phase separation agent apatite through four-angle-method. The effect of iron oxide contents, phase separation and the firing temperature on the color of Jun ware glazes were investigated by a neutral atmosphere experiment, optical microscope and scanning electronic microscope. The results showed that the colorant, mainly Fe2O3, contributed to the Jun ware glaze blue and cyan colors of Jun ware glaze. The light scatter caused by the small droplets in phase separation structure only influenced the shade of the glaze color, intensify or weaken the color, and thus made the glaze perfect and elegant opal visual effects, but was not the origin of general blue or cyan colors of Jun ware glaze. In addition, the firing temperature and the basic glaze composition affected the glaze colors to some extent.

  8. Device for two-dimensional gas-phase separation and characterization of ion mixtures

    DOEpatents

    Tang, Keqi; Shvartsburg, Alexandre A.; Smith, Richard D.

    2006-12-12

    The present invention relates to a device for separation and characterization of gas-phase ions. The device incorporates an ion source, a field asymmetric waveform ion mobility spectrometry (FAIMS) analyzer, an ion mobility spectrometry (IMS) drift tube, and an ion detector. In one aspect of the invention, FAIMS operating voltages are electrically floated on top of the IMS drift voltage. In the other aspect, the FAIMS/IMS interface is implemented employing an electrodynamic ion funnel, including in particular an hourglass ion funnel. The present invention improves the efficiency (peak capacity) and sensitivity of gas-phase separations; the online FAIMS/IMS coupling creates a fundamentally novel two-dimensional gas-phase separation technology with high peak capacity, specificity, and exceptional throughput.

  9. Recent progress of chiral stationary phases for separation of enantiomers in gas chromatography.

    PubMed

    Xie, Sheng-Ming; Yuan, Li-Ming

    2017-01-01

    Chromatography techniques based on chiral stationary phases are widely used for the separation of enantiomers. In particular, gas chromatography has developed rapidly in recent years due to its merits such as fast analysis speed, lower consumption of stationary phases and analytes, higher column efficiency, making it a better choice for chiral separation in diverse industries. This article summarizes recent progress of novel chiral stationary phases based on cyclofructan derivatives and chiral porous materials including chiral metal-organic frameworks, chiral porous organic frameworks, chiral inorganic mesoporous materials, and chiral porous organic cages in gas chromatography, covering original research papers published since 2010. The chiral recognition properties and mechanisms of separation toward enantiomers are also introduced.

  10. Theory of spatiotemporally resolved spectroscopy for phase-separation dynamics in electron-hole systems

    NASA Astrophysics Data System (ADS)

    Ishikawa, Akira

    2013-02-01

    Phase separation such as the formation of electron-hole droplets has been observed in semiconductor electron-hole systems. In such conventional experiments, the information averaged in real space was obtained. However, in recent years, optical-near-field techniques have enabled us to acquire spatial information. In this study, I propose a theoretical formulation of spatiotemporal dynamics and spatiotemporally resolved optical response of the gas-liquid phase separation in electron-hole systems. In addition, the nature of the nonequilibrium open system is an essential point in electron-hole systems. Therefore, I investigate the effect of the finite lifetime of electron-hole pairs on phase-separation dynamics. Contribution to the Topical Issue "Excitonic Processes in Condensed Matter, Nanostructured and Molecular Materials", edited by Maria Antonietta Loi, Jasper Knoester and Paul H. M. van Loosdrecht.

  11. Influence of red blood cell clustering on phase separation in capillary networks

    NASA Astrophysics Data System (ADS)

    Podgorski, Thomas; Boucly, Celine; Coupier, Gwennou

    2014-11-01

    We investigate the flow of red blood cell suspensions in microfluidic bifurcations and capillary networks. At strong degrees of confinement, such as those encountered in the microcirculation, phase separation takes place at bifurcations of the network, leading to strong heterogeneities and fluctuations of the hematocrit (blood cell concentration). We highlight the influence of the mechanical properties of cells : an increase of membrane or cytoplasm rigidity, as can happen in pathologies such as sickle cell disease tends to reduce the phase separation. The influence of the attractive interaction between cells, that leads to clustering (rouleau formation) was also investigated by varying the concentration of macromolecules in the solution (dextran or fibrinogen). We show that hydrodynamic stresses in bifurcations can lead to rupture of clusters at a critical speed which increases with interaction energy. Overall, the clustering phenomenon tends to increase phase separation and hematocrit heterogeneities.

  12. Coarse-grained molecular dynamics simulation of binary charged lipid membranes: Phase separation and morphological dynamics

    NASA Astrophysics Data System (ADS)

    Ito, Hiroaki; Higuchi, Yuji; Shimokawa, Naofumi

    2016-10-01

    Biomembranes, which are mainly composed of neutral and charged lipids, exhibit a large variety of functional structures and dynamics. Here, we report a coarse-grained molecular dynamics (MD) simulation of the phase separation and morphological dynamics in charged lipid bilayer vesicles. The screened long-range electrostatic repulsion among charged head groups delays or inhibits the lateral phase separation in charged vesicles compared with neutral vesicles, suggesting the transition of the phase-separation mechanism from spinodal decomposition to nucleation or homogeneous dispersion. Moreover, the electrostatic repulsion causes morphological changes, such as pore formation, and further transformations into disk, string, and bicelle structures, which are spatiotemporally coupled to the lateral segregation of charged lipids. Based on our coarse-grained MD simulation, we propose a plausible mechanism of pore formation at the molecular level. The pore formation in a charged-lipid-rich domain is initiated by the prior disturbance of the local molecular orientation in the domain.

  13. Therapeutic Antibody Engineering To Improve Viscosity and Phase Separation Guided by Crystal Structure.

    PubMed

    Chow, Chi-Kin; Allan, Barrett W; Chai, Qing; Atwell, Shane; Lu, Jirong

    2016-03-07

    Antibodies at high concentrations often reveal unanticipated biophysical properties suboptimal for therapeutic development. The purpose of this work was to explore the use of point mutations based on crystal structure information to improve antibody physical properties such as viscosity and phase separation (LLPS) at high concentrations. An IgG4 monoclonal antibody (Mab4) that exhibited high viscosity and phase separation at high concentration was used as a model system. Guided by the crystal structure, four CDR point mutants were made to evaluate the role of hydrophobic and charge interactions on solution behavior. Surprisingly and unpredictably, two of the charge mutants, R33G and N35E, showed a reduction in viscosity and a lower propensity to form LLPS at high concentration compared to the wild-type (WT), while a third charge mutant S28K showed an increased propensity to form LLPS compared to the WT. A fourth mutant, F102H, had reduced hydrophobicity, but unchanged viscosity and phase separation behavior. We further evaluated the correlation of various biophysical measurements including second virial coefficient (A2), interaction parameter (kD), weight-average molecular weight (WAMW), and hydrodynamic diameters (DH), at relatively low protein concentration (4 to 15 mg/mL) to physical properties, such as viscosity and liquid-liquid phase separation (LLPS), at high concentration. Surprisingly, kD measured using dynamic light scattering (DLS) at low antibody concentration correlated better with viscosity and phase separation than did A2 for Mab4. Our results suggest that the high viscosity and phase separation observed at high concentration for Mab4 are mainly driven by charge and not hydrophobicity.

  14. Anion separations for liquid chromatography using propylpyridinium silica as the stationary phase.

    PubMed

    Auler, Lúcia M L A; Silva, César R; Bottoli, Carla B G; Collins, Carol H

    2011-05-30

    This work describes the characterization and potential applications of a silica-based anion-exchange phase prepared by a two-step modification process that incorporates a propylpyridinium group. The effects of pH and eluent concentration on anion separation were examined using 150 mm × 3.9 mm HPLC columns packed with the new phase. The mobile phase pH values ranged from 3.8 to 6.6 using phthalic acid/Tris solutions. The best separation was achieved using 2.5 mmol L(-1) phthalate/2.4 mmol L(-1) Tris solution at pH 4.2 as mobile phase with non-suppressed conductivity detection. The new stationary phase was used for the separation of some inorganic and organic anions showing good resolution. The stability of the silica-based anion exchange phase was also evaluated. Analytical curves, for concentrations ranging from 0.25 to 10 mg L(-1) for the inorganic anions chloride, nitrite, bromide and nitrate, showed good linear correlations (r>0.998). The method was tested with certified rainwater samples. The measured and certified values were in good agreement, indicating that the new phase holds significant promise for the analysis of these anions in environmental samples.

  15. Exploring the dynamics of phase separation in colloid-polymer mixtures with long range attraction.

    PubMed

    Sabin, Juan; Bailey, Arthur E; Frisken, Barbara J

    2016-06-28

    We have studied the kinetics of phase separation and gel formation in a low-dispersity colloid - non-adsorbing polymer system with long range attraction using small-angle light scattering. This system exhibits two-phase and three-phase coexistence of gas, liquid and crystal phases when the strength of attraction is between 2 and 4kBT and gel phases when the strength of attraction is increased. For those samples that undergo macroscopic phase separation, whether to gas-crystal, gas-liquid or gas-liquid-crystal coexistence, we observe dynamic scaling of the structure factor and growth of a characteristic length scale that behaves as expected for phase separation in fluids. In samples that gel, the power law associated with the growth of the dominant length scale is not equal to 1/3, but appears to depend mainly on the strength of attraction, decreasing from 1/3 for samples near the coexistence region to 1/27 at 8kBT, over a wide range of colloid and polymer concentrations.

  16. Local v/a variations as a measure of structural packing frustration in bicontinuous mesophases, and geometric arguments for an alternating Imoverline{{mathsf3}}m (I-WP) phase in block-copolymers with polydispersity

    NASA Astrophysics Data System (ADS)

    Schröder-Turk, G. E.; Fogden, A.; Hyde, S. T.

    2007-09-01

    This article explores global geometric features of bicontinuous space-partitions and their relevance to self-assembly of block-copolymers. Using a robust definition of `local channel radius', based on the concept of a medial surface [Schröder et al., Eur. Phys. J. B 35, 551 (2003)], we relate radius variations of the space-partition to polymolecular chain stretching in bicontinuous diblock- and terblock copolymer assemblies. We associate local surface patches with corresponding cellular volume elements, to define local volume-to-surface ratios. The distribution of these v/a ratios and of the channel radii are used to quantify the degree of packing frustration of molecular chains as a function of the specific bicontinuous geometry, modelled by triply-periodic minimal surfaces and related parallel interfaces. The Gyroid geometry emerges as the most nearly homogeneous bicontinuous form, with the smallest heterogeneity of channel radii, compared to the cubic Primitive and Diamond surfaces. We clarify a geometric feature of the Gyroid geometry: the three-coordinated nodes of the graph are not the widest points of the labyrinths; the widest points are at the midpoints of the edges. We also explore a more complex cubic triply-periodic surface, the I-WP surface, containing two geometrically distinct channel subdomains. One of the two channel systems is nearly as homogeneous in local channel diameters as the Gyroid, the other is more heterogeneous than the Primitive surface. Its hybrid nature suggests the possibility of an “alternating I-WP” phase in polydisperse linear ABC-terpolymer blends, with monodisperse molecular weight distributions (MWD) in the A and B blocks and a more polydisperse C block. Abbreviations used throughout this article: CMC: constant mean curvature, IMDS: inter-material dividing surface, TPMS: triply-periodic minimal surface, MS: medial surface, K: Gaussian curvature, H: mean curvature, SCFT: self-consistent field theory, LG: labyrinth graph

  17. How to separate ionic liquids: use of hydrophilic interaction liquid chromatography and mixed mode phases.

    PubMed

    Lamouroux, C; Foglia, G; Le Rouzo, G

    2011-05-20

    This chromatographic study deals with the development of a convenient and versatile method to separate Room Temperature Ionic Liquids. Different modes of chromatography were studied. The study attempts to answer the following question: "what were the most important interactions for the separation of ionic liquids?". The results show that the essential interactions to assure a good retention of RTILs are the ionic ones and that hydrophobic interactions play a role in the selectivity of the separation. The separation of five imidazolium salt with a traditional diol columns in Hydrophilic Interaction Chromatography (HILIC) was demonstrated. It shows that neutral diol grafted column allows an important retention that we assume is due to the capability of diol to develop a thick layer of water. Furthermore, stationary phase based on mixed interaction associating ion exchange and hydrophobic properties were studied. Firstly, it will be argued that it is possible to separate RTILs with a convenient retention and resolution according to a reverse phase elution with the Primesep columns made of a brush type long alkyl chain with an embedded negatively charged functional group. Secondly, a sucessful separation of RTILs in HILIC mode with a mixed phase column containing a cationic exchanger and a hydrophobic octyl chain length will be demonstrated.

  18. Systematic Approach to Links between Separations in MEKC and Reversed-Phase HPLC.

    PubMed

    Ferguson, P D; Goodall, D M; Loran, J S

    1998-10-01

    Retention factors and partition coefficients in micellar electrokinetic chromatography (MEKC) and reversed-phase high-performance liquid chromatography (RP-HPLC) are compared for a series of alkylbenzenes and substituted phenols. In both techniques, separations are based on partitioning between an aqueous phase and an alkyl phase. In MEKC, this was an SDS (C12) micellar pseudostationary phase, and in RP-HPLC an ODS 2 (C18) stationary phase. A nonporous silica (Micra 1.5-μm NPS), which has a low carbon loading, was used rather than a standard porous silica to avoid excessive retention in HPLC and to allow identical mobile phase conditions to be used in both separation modes. The average ratio of analyte retention factors, k(MEKC):k(HPLC), was found to be equal to the ratio β(MEKC):β(HPLC), where β is the phase ratio. This implies that partition coefficients, P, are similar in both MEKC and HPLC, since P = k/β, and that the dominant contribution to stability within each alkyl phase arises from hydrophobic interactions which are common to both separation media. Since partition coefficients are similar in MEKC and HPLC under aqueous buffer conditions, information on retention in one technique may be transferred to the other, provided that the phase ratios are known. In MEKC and HPLC, linear correlations of log octanol-water partition coefficients, K(ow), vs log k for the test compounds were transformed, knowing the phase ratio, to give log P values as a function of log K(ow). This allows quantitative links between MEKC and HPLC to be extended to include octanol-water partitioning. The addition of acetonitrile as an organic modifier over the concentration range 0-20% (v/v) was found to have a greater effect on k in HPLC than in MEKC. This could be a result of a decrease in the MEKC phase ratio due to an increase in the critical micelle concentration.

  19. Controlling phase separation of binary Bose-Einstein condensates via mixed-spin-channel Feshbach resonance

    SciTech Connect

    Tojo, Satoshi; Taguchi, Yoshihisa; Masuyama, Yuta; Hayashi, Taro; Hirano, Takuya; Saito, Hiroki

    2010-09-15

    We investigate controlled phase separation of a binary Bose-Einstein condensate in the proximity of a mixed-spin-channel Feshbach resonance in the |F=1,m{sub F}=+1> and |F=2,m{sub F}=-1> states of {sup 87}Rb at a magnetic field of 9.10 G. Phase separation occurs on the lower-magnetic-field side of the Feshbach resonance while the two components overlap on the higher-magnetic-field side. The Feshbach resonance curve of the scattering length is obtained from the shape of the atomic cloud by comparison with the numerical analysis of coupled Gross-Pitaevskii equations.

  20. Submicron-scale manipulation of phase separation in organic solar cells

    NASA Astrophysics Data System (ADS)

    Chen, Fang-Chung; Lin, Yi-Kai; Ko, Chu-Jung

    2008-01-01

    This paper describes a method for controlling the submicron-scale phase separation of poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester in organic solar cells. Using microcontact printing of self-assembled monolayers on the device buffer layer to divide the surface into two regimes having different surface energies, an interdigitated structure aligned vertical to the substrate surface is achieved after spontaneous surface-directed phase separation. The power conversion efficiency increases upon decreasing the grating spacing, reaching 2.47%. The hole mobility increased as a consequence of improved polymer chain ordering, resulting in higher device efficiency, while smaller pattern sizes were used.

  1. Feedback stabilization of the Cahn-Hilliard type system for phase separation

    NASA Astrophysics Data System (ADS)

    Barbu, Viorel; Colli, Pierluigi; Gilardi, Gianni; Marinoschi, Gabriela

    2017-02-01

    This article is concerned with the internal feedback stabilization of the phase field system of Cahn-Hilliard type, modeling the phase separation in a binary mixture. Under suitable assumptions on an arbitrarily fixed stationary solution, we construct via spectral separation arguments a feedback controller having its support in an arbitrary open subset of the space domain, such that the closed loop nonlinear system exponentially reaches the prescribed stationary solution. This feedback controller has a finite dimensional structure in the state space of solutions. In particular, every constant stationary solution is admissible.

  2. Influence of recrystallization on phase separation kinetics of oxide dispersion strengthened Fe Cr Al alloy

    SciTech Connect

    Capdevila, C.; Miller, Michael K; Pimentel, G.; Chao, J.

    2012-01-01

    The effect of different starting microstructures on the kinetics of Fe-rich ({alpha}) and Cr-rich ({alpha}') phase separation during aging of Fe-Cr-Al oxide dispersion strengthened (ODS) alloys has been analyzed with a combination of atom probe tomography and thermoelectric power measurements. The results revealed that the high recrystallization temperature necessary to produce a coarse grained microstructure in Fe-base ODS alloys affects the randomness of Cr-atom distributions and defect density, which consequently affect the phase separation kinetics at low annealing temperatures.

  3. [Separation of enantiomers by supercritical fluid chromatography on polysaccharide derivative-based chiral stationary phases].

    PubMed

    Li, Dongyan; Wu, Xi; Hao, Fangli; Yang, Yang; Chen, Xiaoming

    2016-01-01

    Eleven kinds of chiral compounds have been well separated within 10 min on polysaccharide derivative-based chiral stationary phases named Chiralpak IA, IB, IC, ID, IE and IF by supercritical fluid chromatography (SFC). The chiral recognition of these chiral compounds has demonstrated good complementary enantioselectivities of the six chiral columns, which were proved to be useful for chiral SFC. Both the elution time and enantioselectivies could be significantly affected by the modifier types and their concentrations, such as methanol, ethanol and isopropanol, which should be optimized during the experiments. In addition, the solvent versatility of the immobilized chiral stationary phase on the optimization of the chiral separation was helpful.

  4. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    DOE PAGES

    Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel A.; ...

    2016-05-16

    Here, three-dimensional chemical imaging of Fe–Cr alloys showing Fe-rich (α)/Cr-rich (α') phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe–Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100–10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni–Mn–Si–Cu-rich G-phase precipitates form at the α/α' interfaces in both alloys. For the 2101more » alloy, Cu clusters act to form a nucleus, around which a Ni–Mn–Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core–shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby–Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30–36).« less

  5. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    SciTech Connect

    Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel A.; Young, George A.; Guo, Wei; Poplawsky, Jonathan D.

    2016-05-16

    Here, three-dimensional chemical imaging of Fe–Cr alloys showing Fe-rich (α)/Cr-rich (α') phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe–Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100–10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni–Mn–Si–Cu-rich G-phase precipitates form at the α/α' interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni–Mn–Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core–shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby–Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30–36).

  6. An atom probe perspective on phase separation and precipitation in duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Guo, Wei; Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel; Young, George A.; Poplawsky, Jonathan D.

    2016-06-01

    Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α‧) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α‧ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36). ).

  7. Fraction transfer process in on-line comprehensive two-dimensional liquid-phase separations.

    PubMed

    Česla, Petr; Křenková, Jana

    2017-01-01

    Two-dimensional liquid-phase separations have gained increasing attention for their ability to separate complex sample mixtures. Among the experimental setups used, an on-line approach is preferred to reduce the probability of sample contamination, for easier automation and high-sample throughput. The interfacing of the separation techniques in the on-line mode brings additional demands on proper optimization of the two-dimensional system. In this review, the possibilities of the on-line coupling of liquid chromatography and liquid chromatography with capillary electrophoresis in two-dimensional systems are discussed. Special attention is paid to the fraction transfer process, which includes an overview of interfaces and experimental setups applied, the compatibility issues of separation systems, and instrumental parameters. The benefits and drawbacks of using electromigration separations in combination with liquid chromatography are presented as well.

  8. Parametric study on phase separation of binary mixtures in a lid driven cavity: A DPD study

    NASA Astrophysics Data System (ADS)

    Gidituri, Harinadha; Anand, Vijay; Panchagnula, Mahesh; Vedantam, Srikanth

    2016-11-01

    We investigate the phase separation behavior of binary mixtures in two dimensional periodic and lid driven cavity domains using dissipative particle dynamics (DPD). The effect of DPD parameters like repulsion coefficient, dissipative coefficient, cut-off radius, and weight function exponent on domain size growth has been studied. The phase separation is delayed for low values of repulsion coefficient. Under these conditions, a few clusters of the dispersed phase are distributed in a continuous phase. This is because of weak inter-particle repulsion. As we increase the repulsion coefficient value, this behavior disappears. The domain growth rate is also observed to increase with an increase in the value of the dissipation coefficient as well as cut-off radius. Finally, the dynamics of phase separation in the lid driven cavity problem are significantly different when compared to that in the periodic domain, due to the formation of a stable vortex in the cavity. The vortex results in a dynamic equilibrium between clustering and separation. The distribution of cluster sizes is studied as a function of the driven cavity parameters.

  9. Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Odqvist, Joakim; Colliander, Magnus Hörnqvist; Thuvander, Mattias; Steuwer, Axel; Westraadt, Johan E.; King, Stephen; Hedström, Peter

    2016-12-01

    Self-assembly due to phase separation within a miscibility gap is important in numerous material systems and applications. A system of particular interest is the binary alloy system Fe-Cr, since it is both a suitable model material and the base system for the stainless steel alloy category, suffering from low-temperature embrittlement due to phase separation. Structural characterization of the minute nano-scale concentration fluctuations during early phase separation has for a long time been considered a major challenge within material characterization. However, recent developments present new opportunities in this field. Here, we present an overview of the current capabilities and limitations of different techniques. A set of Fe-Cr alloys were investigated using small-angle neutron scattering (SANS), atom probe tomography, and analytical transmission electron microscopy. The complementarity of the characterization techniques is clear, and combinatorial studies can provide complete quantitative structure information during phase separation in Fe-Cr alloys. Furthermore, we argue that SANS provides a unique in-situ access to the nanostructure, and that direct comparisons between SANS and phase-field modeling, solving the non-linear Cahn Hilliard equation with proper physical input, should be pursued.

  10. Phase separation kinetics in amorphous solid dispersions upon exposure to water.

    PubMed

    Purohit, Hitesh S; Taylor, Lynne S

    2015-05-04

    The purpose of this study was to develop a novel fluorescence technique employing environment-sensitive fluorescent probes to study phase separation kinetics in hydrated matrices of amorphous solid dispersions (ASDs) following storage at high humidity and during dissolution. The initial miscibility of the ASDs was confirmed using infrared (IR) spectroscopy and differential scanning calorimetry (DSC). Fluorescence spectroscopy, as an independent primary technique, was used together with conventional confirmatory techniques including DSC, X-ray diffraction (XRD), fluorescence microscopy, and IR spectroscopy to study phase separation phenomena. By monitoring the emission characteristics of the environment-sensitive fluorescent probes, it was possible to successfully monitor amorphous-amorphous phase separation (AAPS) as a function of time in probucol-poly(vinylpyrrolidone) (PVP) and ritonavir-PVP ASDs after exposure to water. In contrast, a ritonavir-hydroxypropylmethylcellulose acetate succinate (HPMCAS) ASD, did not show AAPS and was used as a control to demonstrate the capability of the newly developed fluorescence method to differentiate systems that showed no phase separation following exposure to water versus those that did. The results from the fluorescence studies were in good agreement with results obtained using various other complementary techniques. Thus, fluorescence spectroscopy can be utilized as a fast and efficient tool to detect and monitor the kinetics of phase transformations in amorphous solid dispersions during hydration and will help provide mechanistic insight into the stability and dissolution behavior of amorphous solid dispersions.

  11. Phase separation in aqueous solutions of lens gamma-crystallins: special role of gamma s.

    PubMed Central

    Liu, C; Asherie, N; Lomakin, A; Pande, J; Ogun, O; Benedek, G B

    1996-01-01

    We have studied liquid-liquid phase separation in aqueous ternary solutions of calf lens gamma-crystallin proteins. Specifically, we have examined two ternary systems containing gamma s--namely, gamma IVa with gamma s in water and gamma II with gamma s in water. For each system, the phase-separation temperatures (Tph (phi)) alpha as a function of the overall protein volume fraction phi at various fixed compositions alpha (the "cloud-point curves") were measured. For the gamma IVa, gamma s, and water ternary solution, a binodal curve composed of pairs of coexisting points, (phi I, alpha 1) and (phi II, alpha II), at a fixed temperature (20 degrees C) was also determined. We observe that on the cloud-point curve the critical point is at a higher volume fraction than the maximum phase-separation temperature point. We also find that typically the difference in composition between the coexisting phases is at least as significant as the difference in volume fraction. We show that the asymmetric shape of the cloud-point curve is a consequence of this significant composition difference. Our observation that the phase-separation temperature of the mixtures in the high volume fraction region is strongly suppressed suggests that gamma s-crystallin may play an important role in maintaining the transparency of the lens. PMID:8552642

  12. Glucaminium ionic liquid-functionalized stationary phase for the separation of nucleosides in hydrophilic interaction chromatography.

    PubMed

    Jiang, Qiong; Zhang, Mingliang; Wang, Xusheng; Guo, Yong; Qiu, Hongdeng; Zhang, Shusheng

    2015-10-01

    A glucaminium-based ionic liquid stationary phase was prepared via facile epoxy-amine reaction and subsequent quaternization. Successful immobilization of glucaminium-based ionic liquid onto silica surface was validated by elemental analysis and infrared spectroscopy. The new stationary phase was evaluated for the separation of nucleosides in hydrophilic interaction liquid chromatography (HILIC). Effects of various factors, such as acetonitrile concentration, salt concentration, pH value, as well as column temperature, on the chromatographic behavior toward nucleosides were studied in detail. The results indicated that this new stationary phase can be used for separation of water-soluble polar substances in HILIC mode. The retention of solutes on the stationary phase was influenced by a mixed-mode retention mechanism with a combination of adsorptive and partitioning interactions.

  13. Heavy-Fermion Valence-Bond Liquids in Ultracold Atoms: Cooperation of the Kondo Effect and Geometric Frustration.

    PubMed

    Isaev, L; Rey, A M

    2015-10-16

    We analyze a microscopic mechanism behind the coexistence of a heavy Fermi liquid and geometric frustration in Kondo lattices. We consider a geometrically frustrated periodic Anderson model and demonstrate how orbital fluctuations lead to a Kondo-screened phase in the limit of extreme strong frustration when only local singlet states participate in the low-energy physics. We also propose a setup to realize and study this exotic state with SU(3)-symmetric alkaline-earth cold atoms.

  14. Stress reduction in phase-separated, cross-linked networks: influence of phase structure and kinetics of reaction.

    PubMed

    Szczepanski, Caroline R; Stansbury, Jeffrey W

    2014-10-05

    A mechanism for polymerization shrinkage and stress reduction was developed for heterogeneous networks formed via ambient, photo-initiated polymerization-induced phase separation (PIPS). The material system used consists of a bulk homopolymer matrix of triethylene glycol dimethacrylate (TEGDMA) modified with one of three non-reactive, linear prepolymers (poly-methyl, ethyl and butyl methacrylate). At higher prepolymer loading levels (10-20 wt%) an enhanced reduction in both shrinkage and polymerization stress is observed. The onset of gelation in these materials is delayed to a higher degree of methacrylate conversion (~15-25%), providing more time for phase structure evolution by thermodynamically driven monomer diffusion between immiscible phases prior to network macro-gelation. The resulting phase structure was probed by introducing a fluorescently tagged prepolymer into the matrix. The phase structure evolves from a dispersion of prepolymer at low loading levels to a fully co-continuous heterogeneous network at higher loadings. The bulk modulus in phase separated networks is equivalent or greater than that of poly(TEGDMA), despite a reduced polymerization rate and cross-link density in the prepolymer-rich domains.

  15. Stress reduction in phase-separated, cross-linked networks: influence of phase structure and kinetics of reaction

    PubMed Central

    Szczepanski, Caroline R.; Stansbury, Jeffrey W.

    2014-01-01

    A mechanism for polymerization shrinkage and stress reduction was developed for heterogeneous networks formed via ambient, photo-initiated polymerization-induced phase separation (PIPS). The material system used consists of a bulk homopolymer matrix of triethylene glycol dimethacrylate (TEGDMA) modified with one of three non-reactive, linear prepolymers (poly-methyl, ethyl and butyl methacrylate). At higher prepolymer loading levels (10–20 wt%) an enhanced reduction in both shrinkage and polymerization stress is observed. The onset of gelation in these materials is delayed to a higher degree of methacrylate conversion (~15–25%), providing more time for phase structure evolution by thermodynamically driven monomer diffusion between immiscible phases prior to network macro-gelation. The resulting phase structure was probed by introducing a fluorescently tagged prepolymer into the matrix. The phase structure evolves from a dispersion of prepolymer at low loading levels to a fully co-continuous heterogeneous network at higher loadings. The bulk modulus in phase separated networks is equivalent or greater than that of poly(TEGDMA), despite a reduced polymerization rate and cross-link density in the prepolymer-rich domains. PMID:25418999

  16. Analysis of Phase Separation in High Performance PbTe–PbS Thermoelectric Materials

    SciTech Connect

    Girard, Steven N.; Schmidt-Rohr, Klaus; Chasapis, Thomas C.; Hatzikraniotis, Euripides; Njegic, B.; Levin, E. M.; Rawal, A.; Paraskevopoulos, Konstantios M.; Kanatzidis, Mercouri G.

    2013-02-11

    Phase immiscibility in PbTe–based thermoelectric materials is an effective means of top-down synthesis of nanostructured composites exhibiting low lattice thermal conductivities. PbTe1-x Sx thermoelectric materials can be synthesized as metastable solid solution alloys through rapid quenching. Subsequent post-annealing induces phase separation at the nanometer scale, producing nanostructures that increase phonon scattering and reduce lattice thermal conductivity. However, there has yet to be any study investigating in detail the local chemical structure of both the solid solution and nanostructured variants of this material system. Herein, quenched and annealed (i.e., solid solution and phase-separated) samples of PbTe–PbS are analyzed by in situ high-resolution synchrotron powder X-ray diffraction, solid-state 125Te nuclear magnetic resonance (NMR), and infrared (IR) spectroscopy analysis. For high concentrations of PbS in PbTe, e.g., x >16%, NMR and IR analyses reveal that rapidly quenched samples exhibit incipient phase separation that is not detected by state-of-the-art synchrotron X-ray diffraction, providing an example of a PbTe thermoelectric “alloy” that is in fact phase inhomogeneous. Thermally-induced PbS phase separation in PbTe–PbS occurs close to 200 °C for all compositions studied, and the solubility of the PbS phase in PbTe at elevated temperatures >500 °C is reported. The findings of this study suggest that there may be a large number of thermoelectric alloy systems that are phase inhomogeneous or nanostructured despite adherence to Vegard's Law of alloys, highlighting the importance of careful chemical characterization to differentiate between thermoelectric alloys and composites.

  17. Cell separation in immunoaffinity partition in aqueous polymer two-phase systems

    NASA Technical Reports Server (NTRS)

    Karr, Laurel J.; Van Alstine, James M.; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

    1989-01-01

    Two methods for immunoaffinity partitioning are described. One technique involves the covalent coupling of poly (ethylene glycol) (PEG) to immunoglobulin G antibody preparations. In the second method PEG-modified Protein A is used to complex with cells and unmodified antibody. The effects of PEG molecular weight, the degree of modification, and varying phase system composition on antibody activity and its affinity for the upper phase are studied. It is observed that both methods resulted in effective cell separation.

  18. Hydrodynamic effects on phase separation morphologies in evaporating thin films of polymer solutions

    NASA Astrophysics Data System (ADS)

    Zoumpouli, Garyfalia A.; Yiantsios, Stergios G.

    2016-08-01

    We examine effects of hydrodynamics on phase separation morphologies developed during drying of thin films containing a volatile solvent and two dissolved polymers. Cahn-Hilliard and Flory-Huggins theories are used to describe the free energy of the phase separating systems. The thin films, considered as Newtonian fluids, flow in response to Korteweg stresses arising due to concentration non-uniformities that develop during solvent evaporation. Numerical simulations are employed to investigate the effects of a Peclet number, defined in terms of system physical properties, as well as the effects of parameters characterizing the speed of evaporation and preferential wetting of the solutes at the gas interface. For systems exhibiting preferential wetting, diffusion alone is known to favor lamellar configurations for the separated phases in the dried film. However, a mechanism of hydrodynamic instability of a short length scale is revealed, which beyond a threshold Peclet number may deform and break the lamellae. The critical Peclet number tends to decrease as the evaporation rate increases and to increase with the tendency of the polymers to selectively wet the gas interface. As the Peclet number increases, the instability moves closer to the gas interface and induces the formation of a lateral segregation template that guides the subsequent evolution of the phase separation process. On the other hand, for systems with no preferential wetting or any other property asymmetries between the two polymers, diffusion alone favors the formation of laterally separated configurations. In this case, concentration perturbation modes that lead to enhanced Korteweg stresses may be favored for sufficiently large Peclet numbers. For such modes, a second mechanism is revealed, which is similar to the solutocapillary Marangoni instability observed in evaporating solutions when interfacial tension increases with the concentration of the non-volatile component. This mechanism may lead

  19. More Opportunities than Wealth. A Network of Power and Frustration

    SciTech Connect

    Mahault, Benoit Alexandre; Saxena, Avadh Behari; Nisoli, Cristiano

    2015-08-17

    We introduce a minimal agent-based model to qualitatively conceptualize the allocation of limited wealth among more abundant opportunities. We study the interplay of power, satisfaction and frustration in the problem of wealth distribution, concentration, and inequality. This framework allows us to compare subjective measures of frustration and satisfaction to collective measures of fairness in wealth distribution, such as the Lorenz curve and the Gini index. We find that a completely libertarian, law-of-the-jungle setting, where every agent can acquire wealth from, or lose wealth to, anybody else invariably leads to a complete polarization of the distribution of wealth vs. opportunity, only minimally ameliorated by disorder in a non-optimized society. The picture is however dramatically modified when hard constraints are imposed over agents, and they are forced to share wealth with neighbors on a network. We discuss the case of random networks and scale free networks. We then propose an out of equilibrium dynamics of the networks, based on a competition of power and frustration in the decision-making of agents that leads to network evolution. We show that the ratio of power and frustration controls different dynamical regimes separated by kinetic transition and characterized by drastically different values of the indices of equality.

  20. Nanoscale phase separation and superconductivity in the one-dimensional Hirsch model

    NASA Astrophysics Data System (ADS)

    Anfossi, Alberto; Degli Esposti Boschi, Cristian; Montorsi, Arianna

    2009-06-01

    We investigate numerically at various fillings the ground state of the one-dimensional Hubbard model with correlated hopping x (Hirsch model). It is found that, for a large range of filling values n around half filling, and for repulsive Coulomb interaction u≤uc(x,n) , phase separation at a nanoscale (NPS phase) between two conducting phases at different densities occurs when x≳2/3 . The NPS phase is accompanied by the opening of a spin gap and the system behaves as a Luther-Emery liquid with dominant superconducting correlations. Close to half filling, an anomalous peak emerges in the charge structure factor related to the density of doubly occupied sites, which determines the size of the droplets in the NPS phase. For 1/2≲x≲2/3 a crossover to a homogeneous phase, still superconducting, takes place.

  1. A Preliminary Assessment of Phase Separator Ground-Based and Reduced-Gravity Testing for ALS Systems

    NASA Technical Reports Server (NTRS)

    Hall, Nancy Rabel

    2006-01-01

    A viewgraph presentation of phase separator ground-based and reduced-gravity testing for Advanced Life Support (ALS) systems is shown. The topics include: 1) Multiphase Flow Technology Program; 2) Types of Separators; 3) MOBI Phase Separators; 4) Experiment set-up; and 5) Preliminary comparison/results.

  2. Effect of geometrical frustration on inverse freezing

    NASA Astrophysics Data System (ADS)

    Schmidt, M.; Morais, C. V.; Zimmer, F. M.

    2016-01-01

    The interplay between geometrical frustration (GF) and inverse freezing (IF) is studied within a cluster approach. The model considers first-neighbor (J1) and second-neighbor (J2) intracluster antiferromagnetic interactions between Ising spins on a checkerboard lattice and long-range disordered couplings (J ) among clusters. We obtain phase diagrams of temperature versus J1/J in two cases: the absence of J2 interaction and the isotropic limit J2=J1 , where GF takes place. An IF reentrant transition from the spin-glass (SG) to paramagnetic (PM) phase is found for a certain range of J1/J in both cases. The J1 interaction leads to a SG state with high entropy at the same time that can introduce a low-entropy PM phase. In addition, it is observed that the cluster size plays an important role. The GF increases the PM phase entropy, but larger clusters can give an entropic advantage for the SG phase that favors IF. Therefore, our results suggest that disordered systems with antiferromagnetic clusters can exhibit an IF transition even in the presence of GF.

  3. Intertwined nematic orders in a frustrated ferromagnet

    NASA Astrophysics Data System (ADS)

    Iqbal, Yasir; Ghosh, Pratyay; Narayanan, Rajesh; Kumar, Brijesh; Reuther, Johannes; Thomale, Ronny

    2016-12-01

    We investigate the quantum phases of the frustrated spin-1/2 J1-J2-J3 Heisenberg model on the square lattice with ferromagnetic J1 and antiferromagnetic J2 and J3 interactions. Using the pseudofermion functional renormalization group technique, we find an intermediate paramagnetic phase located between classically ordered ferromagnetic, stripy antiferromagnetic, and incommensurate spiral phases. We observe that quantum fluctuations lead to significant shifts of the spiral pitch angles compared to the classical limit. By computing the response of the system with respect to various spin rotation and lattice symmetry-breaking perturbations, we identify a complex interplay between different nematic spin states in the paramagnetic phase. While retaining time-reversal invariance, these phases either break spin-rotation symmetry, lattice-rotation symmetry, or a combination of both. We therefore propose the J1-J2-J3 Heisenberg model on the square lattice as a paradigmatic example where different intimately connected types of nematic orders emerge in the same model.

  4. Photopolymerization-induced crystallization and phase separation in poly(ethylene oxide)/triacrylate blends

    SciTech Connect

    Park, Soo Jeoung; Kyu, Thein

    2008-12-28

    The present article describes experimental and theoretical investigations of miscibility and crystallization behavior of blends of poly(ethylene oxide) (PEO) and triacrylate monomer (TA) using differential scanning calorimetry and optical microscopy. The PEO/TA blends manifested a single T{sub g} varying systematically with composition suggestive of a miscible character in their amorphous states. Moreover, there occurs melting point depression of PEO crystals with increasing TA. A phase diagram was subsequently established that exhibited a solid+liquid coexistence region bound by the liquidus and solidus lines, followed by an upper critical solution temperature (UCST) at a lower temperature. The emerging phase morphology was investigated to verify the coexistence regions. Upon photopolymerization in the isotropic melt above the melting point depression curve, both the UCST and the melting temperatures move upward and eventually surpass the reaction temperature, resulting in phase separation as well as crystallization of PEO driven by the changing supercooling, i.e., the thermodynamic driving force. Of particular interest is the interplay between photopolymerization-induced phase separation and crystallization, which eventually determines the final phase morphology of the PEO/TA blend such as crystalline lamellae, sheaf, or spherulites in isotropic liquid, phase separated domains, and viscous fingering liquids.

  5. Photopolymerization-induced crystallization and phase separation in poly(ethylene oxide)/triacrylate blends.

    PubMed

    Park, Soo Jeoung; Kyu, Thein

    2008-12-28

    The present article describes experimental and theoretical investigations of miscibility and crystallization behavior of blends of poly(ethylene oxide) (PEO) and triacrylate monomer (TA) using differential scanning calorimetry and optical microscopy. The PEO/TA blends manifested a single T(g) varying systematically with composition suggestive of a miscible character in their amorphous states. Moreover, there occurs melting point depression of PEO crystals with increasing TA. A phase diagram was subsequently established that exhibited a solid+liquid coexistence region bound by the liquidus and solidus lines, followed by an upper critical solution temperature (UCST) at a lower temperature. The emerging phase morphology was investigated to verify the coexistence regions. Upon photopolymerization in the isotropic melt above the melting point depression curve, both the UCST and the melting temperatures move upward and eventually surpass the reaction temperature, resulting in phase separation as well as crystallization of PEO driven by the changing supercooling, i.e., the thermodynamic driving force. Of particular interest is the interplay between photopolymerization-induced phase separation and crystallization, which eventually determines the final phase morphology of the PEO/TA blend such as crystalline lamellae, sheaf, or spherulites in isotropic liquid, phase separated domains, and viscous fingering liquids.

  6. Selective Separation of Fe-Concentrates in EAF Slags Using Mechanical Dissimilarity of Solid Phases

    NASA Astrophysics Data System (ADS)

    Jung, Sung Suk; Jung, Keeyoung; Sohn, Il

    2017-02-01

    We sought to develop an optimized particle size-dependent separation method to lower the Fe content of pulverized glass-ceramic electric arc furnace (EAF) slag for its improved reclamation as construction materials by considering the structures and the mechanical behavior of the discrete solid phases. After an isothermal crystallization process to enhance the spinel growth, the Vickers hardness and fracture toughness were measured on the spinel and amorphous phases separately from the solidified slag using indentation methods. The characteristic differences in the hardness of the phases were magnified when this glass-ceramic composite was isothermally crystallized. The hardness of the spinel was observed to be lower in slags with higher FetO/Al2O3 mass ratios due to the triclinic unit cell expansion of the spinel, whereas the hardness of the amorphous phase decreased with increasing isothermal period because of the structural transformation into a silicate-dominant network. Fracture toughness could be calculated based on the hardness and crack length, where the Young's modulus was determined using nanoindentation. The amorphous phase with a lower Fe content and lower fracture toughness resulted in finer powder distribution after pulverization, allowing better separation of the primary crystalline spinel containing higher Fe content from the Fe-deficient amorphous phase according to the particle size.

  7. Investigation of high velocity separator for particle removal in coal gasification plants. Phase II report

    SciTech Connect

    Linhardt, H.D.

    1980-01-15

    This report summarizes the results of Phase II of the High Velocity Particle Separator Program performed under Contract EF-77-C-01-2709. This high velocity wedge separator has the potential to reduce equipment size and cost of high temperature and pressurized particulate removal equipment for coal derived gases. Phase II has been directed toward testing and detailed conceptual design of an element suitable for a commercial scale high temperature, high pressure particle separator (HTPS). Concurrently, Phase IA has been conducted, which utilized the ambient analog method (AAM) for aerodynamic and collection performance investigation of each HTPS configuration prior and during hot testing. This report summarizes the results of Phase IA and II. The AAM effort established correlation of theoretical analysis and experiment for HTPS pressure drop, purge flow ratio and collection efficiency potential. Task I defined the initial test conditions to be the contract design point of 1800/sup 0/F and 350 psia. The 1800/sup 0/F, 350 psia testing represents the main high temperature testing with coal-derived particulates in the 2 to 10 micron range. Phase IA and Phase II have demonstrated efficient particle collection with acceptable pressure drop. In view of these encouraging results, it is reasonable to apply the developed technology toward future hot gas particulate cleanup requirements.

  8. Liquid-liquid phase separation in supersaturated lysozyme solutions and associated precipitate formation/crystallization

    NASA Astrophysics Data System (ADS)

    Muschol, Martin; Rosenberger, Franz

    1997-08-01

    Using cloud point determinations, the phase boundaries (binodals) for metastable liquid-liquid (L-L) separation in supersaturated hen egg white lysozyme solutions with 3%, 5%, and 7% (w/v) NaCl at pH=4.5 and protein concentrations c between 40 and 400 mg/ml were determined. The critical temperature for the binodal increased approximately linearly with salt concentration. The coexisting liquid phases both remained supersaturated but differed widely in protein concentration. No salt repartitioning was observed between the initial and the two separated liquid phases. After the L-L separation, due to the presence of the high protein concentration phase, crystallization occurred much more rapidly than in the initial solution. At high initial protein concentrations, a metastable gel phase formed at temperatures above the liquid binodal. Both crystal nucleation and gel formation were accelerated in samples that had been cycled through the binodal. Solutions in the gel and L-L regions yielded various types of precipitates. Based on theoretical considerations, previous observations with other proteins, and our experimental results with lysozyme, a generic phase diagram for globular proteins is put forth. A limited region in the (T,c) plane favorable for the growth of protein single crystals is delineated.

  9. Liquid-Liquid Phase Separation in Supersaturated Lysozyme Solutions and Associated Precipitate Formation/Crystallization

    NASA Technical Reports Server (NTRS)

    Muschol, Martin; Rosenberger, Franz

    1997-01-01

    Using cloud point determinations, the phase boundaries (binodals) for metastable liquid-liquid (L-L) separation in supersaturated hen egg white lysozyme solutions with 3%, 5%, and 7% (wlv) NaCl at pH= 4.5 and protein concentrations c between 40 and 400 mg/ml were determined. The critical temperature for the binodal increased approximately linearly with salt concentration. The coexisting liquid phases both remained supersaturated but differed widely in protein concentration. No salt repartitioning was observed between the initial and the two separated liquid phases. After the L-L separation, due to the presence of the high protein concentration phase, crystallization occurred much more rapidly than in the initial solution. At high initial protein concentrations, a metastable gel phase formed at temperatures above the liquid binodal. Both crystal nucleation and gel formation were accelerated in samples that had been cycled through the binodal. Solutions in the gel and L-L regions yielded various types of precipitates. Based on theoretical considerations, previous observations with other proteins, and our experimental results with lysozyme, a generic phase diagram for globular proteins is put forth. A limited region in the (T,c) plane favorable for the growth of protein single crystals is delineated.

  10. Influence of thermal effects on the morphological patterns developed through phase separation in binary systems

    NASA Astrophysics Data System (ADS)

    Borzacchiello, D.; Leygue, A.; Chinesta, F.

    2014-07-01

    This paper is concerned with the modelling and numerical simulation of temperature-induced phase separation (TIPS) coupled with non-uniform temperature fields. The spontaneous phase separation of an initially homogeneous blend can be used, in principle, as a reliable and scalable process to reproduce specific morphologies at the microscopic scale in two-phase composite materials, such as rubber-reinforced resins, or in microstructured porous media. The size of the microstructures that are formed and the degree of anisotropy can be controlled through the imposition of an adequate temperature field. In order to understand the potential use of a temperature gradient to control phase separation, we developed a qualitative model for TIPS based on the Cahn-Hilliard approach and we proposed a computational strategy to obtain numerical solutions for phase separation in confined domains taking into account the thermal interaction with the walls. While the method is based on a volume penalization technique, the novelty of the proposed approach relies on the fact that the penalization term of the equation is constructed on the same theoretical basis from which the Cahn-Hilliard equation is derived. The advantage offered by this technique is that the same pseudo-spectral Fourier discretization schemes that are classically used to solve the Cahn-Hilliard equation in periodic domains can be straightforwardly applied to the case of bounded domains. The application examples shown in this paper emphasize the key role of the dimensionless number given by the ratio of the characteristic heat propagation time and the characteristic time of the phase separation, and demonstrate how control of the microstructure anisotropy could be achieved through TIPS.

  11. Cesium vacancy ordering in phase-separated CsxFe2-ySe2

    DOE PAGES

    Taddei, Keith M.; Sturza, M.; Chung, Duck -Yung; ...

    2015-09-14

    By simultaneously displaying magnetism and superconductivity in a single phase, the iron-based superconductors provide a model system for the study of magnetism's role in superconductivity. The class of intercalated iron selenide superconductors is unique among these in having the additional property of phase separation and coexistence of two distinct phases—one majority phase with iron vacancy ordering and strong antiferromagnetism, and the other a poorly understood minority microscopic phase with a contested structure. Adding to the intrigue, the majority phase has never been found to show superconductivity on its own while the minority phase has never been successfully synthesized separate frommore » the majority phase. In order to better understand this minority phase, a series of high-quality CsxFe2–ySe2 single crystals with (0.8 ≤ x ≤ 1;0 ≤ y ≤ 0.3) were grown and studied. Neutron and x-ray powder diffraction performed on ground crystals show that the average I4/mmm structure of the minority phase is distinctly different from the high-temperature I4/mmm parent structure. Moreover, single-crystal diffraction reveals the presence of discrete superlattice reflections that remove the degeneracy of the Cs sites in both the majority and minority phases and reduce their structural symmetries from body centered to primitive. Group theoretical analysis in conjunction with structural modeling shows that the observed superlattice reflections originate from three-dimensional Cs vacancy ordering. This model predicts a 25% vacancy of the Cs site in the minority phase which is consistent with the site's refined occupancy. Magnetization measurements performed in tandem with neutron single-crystal diffraction provide evidence that the minority phase is the host of superconductivity. Lastly, our results also reveal a superconducting dome in which the superconducting transition temperature varies as a function of the nominal valence of iron.« less

  12. Topological frustration of artificial spin ice

    PubMed Central

    Drisko, Jasper; Marsh, Thomas; Cumings, John

    2017-01-01

    Frustrated systems, typically characterized by competing interactions that cannot all be simultaneously satisfied, display rich behaviours not found elsewhere in nature. Artificial spin ice takes a materials-by-design approach to studying frustration, where lithographically patterned bar magnets mimic the frustrated interactions in real materials but are also amenable to direct characterization. Here, we introduce controlled topological defects into square artificial spin ice lattices in the form of lattice edge dislocations and directly observe the resulting spin configurations. We find the presence of a topological defect produces extended frustration within the system caused by a domain wall with indeterminate configuration. Away from the dislocation, the magnets are locally unfrustrated, but frustration of the lattice persists due to its topology. Our results demonstrate the non-trivial nature of topological defects in a new context, with implications for many real systems in which a typical density of dislocations could fully frustrate a canonically unfrustrated system. PMID:28084314

  13. Topological frustration of artificial spin ice

    NASA Astrophysics Data System (ADS)

    Drisko, Jasper; Marsh, Thomas; Cumings, John

    2017-01-01

    Frustrated systems, typically characterized by competing interactions that cannot all be simultaneously satisfied, display rich behaviours not found elsewhere in nature. Artificial spin ice takes a materials-by-design approach to studying frustration, where lithographically patterned bar magnets mimic the frustrated interactions in real materials but are also amenable to direct characterization. Here, we introduce controlled topological defects into square artificial spin ice lattices in the form of lattice edge dislocations and directly observe the resulting spin configurations. We find the presence of a topological defect produces extended frustration within the system caused by a domain wall with indeterminate configuration. Away from the dislocation, the magnets are locally unfrustrated, but frustration of the lattice persists due to its topology. Our results demonstrate the non-trivial nature of topological defects in a new context, with implications for many real systems in which a typical density of dislocations could fully frustrate a canonically unfrustrated system.

  14. Development of optimized mobile phases for protein separation by high performance thin layer chromatography.

    PubMed

    Biller, Julia; Morschheuser, Lena; Riedner, Maria; Rohn, Sascha

    2015-10-09

    In recent years, protein chemistry tends inexorably toward the analysis of more complex proteins, proteoforms, and posttranslational protein modifications. Although mass spectrometry developed quite fast correspondingly, sample preparation and separation of these analytes is still a major issue and quite challenging. For many years, electrophoresis seemed to be the method of choice; nonetheless its variance is limited to parameters such as size and charge. When taking a look at traditional (thin-layer) chromatography, further parameters such as polarity and different mobile and stationary phases can be utilized. Further, possibilities of detection are manifold compared to electrophoresis. Similarly, two-dimensional separation can be also performed with thin-layer chromatography (TLC). As the revival of TLC developed enormously in the last decade, it seems to be also an alternative to use high performance thin-layer chromatography (HPTLC) for the separation of proteins. The aim of this study was to establish an HPTLC separation system that allows a separation of protein mixtures over a broad polarity range, or if necessary allowing to modify the separation with only few steps to improve the separation for a specific scope. Several layers and solvent systems have been evaluated to reach a fully utilized and optimized separation system.

  15. Separating the strengthening phase in nickel-cobalt alloys doped with tantalum

    NASA Astrophysics Data System (ADS)

    Shaipov, R. Kh.; Kerimov, E. Yu.; Slyusarenko, E. M.

    2017-02-01

    The hardness values of monophasic (fcc solid solution) and biphasic (fcc solid solution and separated phase) nickel-cobalt alloys doped with tantalum are determined using the Vickers method. Based on the resulting data, a composition-structure-hardness diagram is devised for the Co-Ni-Ta system.

  16. A Classroom Demonstration of Water-Induced Phase Separation of Alcohol-Gasoline Biofuel Blends

    ERIC Educational Resources Information Center

    Mueller, Sherry A.; Anderson, James E.; Wallington, Timothy J.

    2009-01-01

    A significant issue associated with ethanol-gasoline blends is the phase separation that occurs with the addition of small volumes of water, producing an ethanol-deficient gasoline layer and an ethanol-rich aqueous layer. The gasoline layer may have a lower-than-desired octane rating due to the decrease in ethanol content, resulting in engine…

  17. Correlating structure with fluorescence emission in phase-separated conjugated-polymer blends.

    PubMed

    Chappell, John; Lidzey, David G; Jukes, Paul C; Higgins, Anthony M; Thompson, Richard L; O'Connor, Stephen; Grizzi, Ilaria; Fletcher, Robert; O'Brien, Jim; Geoghegan, Mark; Jones, Richard A L

    2003-09-01

    Blends of conjugated polymers are frequently used as the active semiconducting layer in light-emitting diodes and photovoltaic devices. Here we report the use of scanning near-field optical microscopy, scanning force microscopy and nuclear-reaction analysis to study the structure of a thin film of a phase-separated blend of two conjugated polymers prepared by spin-casting. We show that in addition to the well-known micrometre-scale phase-separated morphology of the blend, one of the polymers preferentially wets the surface and forms a 10-nm-thick, partially crystallized wetting layer. Using near-field microscopy we identify unexpected changes in the fluorescence emission from the blend that occurs in a 300-nm-wide band located at the interface between the different phase-separated domains. Our measurements provide an insight into the complex structure of phase-separated conjugated-polymer thin films. Characterizing and controlling the properties of the interfaces in such films will be critical in the further development of efficient optoelectronic devices.

  18. Anisotropic imprint of amorphization and phase separation in manganite thin films via laser interference irradiation.

    PubMed

    Ding, Junfeng; Lin, Zhipeng; Wu, Jianchun; Dong, Zhili; Wu, Tom

    2015-02-04

    Materials with mesoscopic structural and electronic phase separation, either inherent from synthesis or created via external means, are known to exhibit functionalities absent in the homogeneous counterparts. One of the most notable examples is the colossal magnetoresistance discovered in mixed-valence manganites, where the coexistence of nano- to micrometer-sized phase-separated domains dictates the magnetotransport. However, it remains challenging to pattern and process such materials into predesigned structures and devices. In this work, a direct laser interference irradiation (LII) method is employed to produce periodic stripes in thin films of a prototypical phase-separated manganite Pr0.65 (Ca0.75 Sr0.25 )0.35 MnO3 (PCSMO). LII induces selective structural amorphization within the crystalline PCSMO matrix, forming arrays with dimensions commensurate with the laser wavelength. Furthermore, because the length scale of LII modification is compatible to that of phase separation in PCSMO, three orders of magnitude of increase in magnetoresistance and significant in-plane transport anisotropy are observed in treated PCSMO thin films. Our results show that LII is a rapid, cost-effective and contamination-free technique to tailor and improve the physical properties of manganite thin films, and it is promising to be generalized to other functional materials.

  19. Configurable lipid membrane gradients quantify diffusion, phase separations and binding densities.

    PubMed

    Liu, Katherine N; Hung, Chen-Min S; Swift, Michael A; Muñoz, Kristen A; Cortez, Jose L; Sanii, Babak

    2015-11-14

    Single-experiment analysis of phospholipid compositional gradients reveals diffusion coefficients, phase separation parameters, and binding densities as a function of localized lipid mixture. Compositional gradients are formed by directed self assembly where rapid-prototyping techniques (i.e., additive manufacturing or laser-cutting) prescribe lipid geometries that self-spread, heal and mix by diffusion.

  20. Realization of a universal and phase-covariant quantum cloning machine in separate cavities

    SciTech Connect

    Fang Baolong; Song Qingming; Ye Liu

    2011-04-15

    We present a scheme to realize a special quantum cloning machine in separate cavities. The quantum cloning machine can copy the quantum information from a photon pulse to two distant atoms. Choosing the different parameters, the method can perform optimal symmetric (asymmetric) universal quantum cloning and optimal symmetric (asymmetric) phase-covariant cloning.

  1. Switchable water: microfluidic investigation of liquid-liquid phase separation mediated by carbon dioxide.

    PubMed

    Lestari, Gabriella; Abolhasani, Milad; Bennett, Darla; Chase, Preston; Günther, Axel; Kumacheva, Eugenia

    2014-08-27

    Increase in the ionic strength of water that is mediated by the reaction of carbon dioxide (CO2) with nitrogenous bases is a promising approach toward phase separation in mixtures of water with organic solvents and potentially water purification. Conventional macroscale studies of this complicated process are challenging, due to its occurrence via several consecutive and concurrent steps, mass transfer limitation, and lack of control over gas-liquid interfaces. We report a new microfluidic strategy for fundamental studies of liquid-liquid phase separation mediated by CO2 as well as screening of the efficiency of nitrogenous agents. A single set of microfluidic experiments provided qualitative and quantitative information on the kinetics and completeness of water-tetrahydrofuran phase separation, the minimum amount of CO2 required to complete phase separation, the total CO2 uptake, and the rate of CO2 consumption by the liquid mixture. The efficiency of tertiary diamines with different lengths of alkyl chain was examined in a time- and labor-efficient manner and characterized with the proposed efficiency parameter. A wealth of information obtained using the MF methodology can facilitate the development of new additives for switchable solvents in green chemistry applications.

  2. Phase Separation of C9orf72 Dipeptide Repeats Perturbs Stress Granule Dynamics.

    PubMed

    Boeynaems, Steven; Bogaert, Elke; Kovacs, Denes; Konijnenberg, Albert; Timmerman, Evy; Volkov, Alex; Guharoy, Mainak; De Decker, Mathias; Jaspers, Tom; Ryan, Veronica H; Janke, Abigail M; Baatsen, Pieter; Vercruysse, Thomas; Kolaitis, Regina-Maria; Daelemans, Dirk; Taylor, J Paul; Kedersha, Nancy; Anderson, Paul; Impens, Francis; Sobott, Frank; Schymkowitz, Joost; Rousseau, Frederic; Fawzi, Nicolas L; Robberecht, Wim; Van Damme, Philip; Tompa, Peter; Van Den Bosch, Ludo

    2017-03-16

    Liquid-liquid phase separation (LLPS) of RNA-binding proteins plays an important role in the formation of multiple membrane-less organelles involved in RNA metabolism, including stress granules. Defects in stress granule homeostasis constitute a cornerstone of ALS/FTLD pathogenesis. Polar residues (tyrosine and glutamine) have been previously demonstrated to be critical for phase separation of ALS-linked stress granule proteins. We now identify an active role for arginine-rich domains in these phase separations. Moreover, arginine-rich dipeptide repeats (DPRs) derived from C9orf72 hexanucleotide repeat expansions similarly undergo LLPS and induce phase separation of a large set of proteins involved in RNA and stress granule metabolism. Expression of arginine-rich DPRs in cells induced spontaneous stress granule assembly that required both eIF2α phosphorylation and G3BP. Together with recent reports showing that DPRs affect nucleocytoplasmic transport, our results point to an important role for arginine-rich DPRs in the pathogenesis of C9orf72 ALS/FTLD.

  3. Effective protein separation by coupling hydrophobic interaction and reverse phase chromatography for top-down proteomics.

    PubMed

    Xiu, Lichen; Valeja, Santosh G; Alpert, Andrew J; Jin, Song; Ge, Ying

    2014-08-05

    One of the challenges in proteomics is the proteome's complexity, which necessitates the fractionation of proteins prior to the mass spectrometry (MS) analysis. Despite recent advances in top-down proteomics, separation of intact proteins remains challenging. Hydrophobic interaction chromatography (HIC) appears to be a promising method that provides high-resolution separation of intact proteins, but unfortunately the salts conventionally used for HIC are incompatible with MS. In this study, we have identified ammonium tartrate as a MS-compatible salt for HIC with comparable separation performance as the conventionally used ammonium sulfate. Furthermore, we found that the selectivity obtained with ammonium tartrate in the HIC mobile phases is orthogonal to that of reverse phase chromatography (RPC). By coupling HIC and RPC as a novel two-dimensional chromatographic method, we have achieved effective high-resolution intact protein separation as demonstrated with standard protein mixtures and a complex cell lysate. Subsequently, the separated intact proteins were identified by high-resolution top-down MS. For the first time, these results have shown the high potential of HIC as a high-resolution protein separation method for top-down proteomics.

  4. Chromatographic separation of phenylpropanol enantiomers on a quinidine carbamate-type chiral stationary phase

    SciTech Connect

    Asnin, Leonid; Guiochon, Georges A

    2005-07-01

    The retention and the separation of the enantiomers of 1-phenylpropanol (1PP), 2-phenylpropanol (2PP), and 3-chloro-1-phenylpropanol (3CPP) on silica-bonded quinidine carbamate under normal phase HPLC conditions were investigated. A relatively high selectivity of the stationary phase for 3CPP and 1PP ({alpha} {approx} 1.07-1.09) was achieved with eluents containing ethyl acetate as the polar modifier. These mobile phases were examined in detail. Based on the set of chromatographic and thermodynamic data collected, conclusions regarding the mechanism of enantioselectivity and the structure of the selector chiral center are made.

  5. Magnetic frustration of graphite oxide

    NASA Astrophysics Data System (ADS)

    Lee, Dongwook; Seo, Jiwon

    2017-03-01

    Delocalized π electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, π electrons develop ferromagnetism due to the unique structure of the material. The π electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negative Curie temperature, field irreversibility, and slow relaxation. The overall results indicate that magnetic moments in graphite oxide slowly interact and develop magnetic frustration.

  6. Magnetic frustration of graphite oxide

    PubMed Central

    Lee, Dongwook; Seo, Jiwon

    2017-01-01

    Delocalized π electrons in aromatic ring structures generally induce diamagnetism. In graphite oxide, however, π electrons develop ferromagnetism due to the unique structure of the material. The π electrons are only mobile in the graphitic regions of graphite oxide, which are dispersed and surrounded by sp3-hybridized carbon atoms. The spin-glass behavior of graphite oxide is corroborated by the frequency dependence of its AC susceptibility. The magnetic susceptibility data exhibit a negative Curie temperature, field irreversibility, and slow relaxation. The overall results indicate that magnetic moments in graphite oxide slowly interact and develop magnetic frustration. PMID:28327606

  7. Separation optimization in reversed-phase liquid chromatography by using alkanol additives in the mobile phase: application to amino acids.

    PubMed

    Pappa-Louisi, A; Agrafiotou, P; Georgiadis, I

    2011-09-30

    In an effort to enhance complex mixture separations by using small amounts of a homologous series of alkanols as additives in the mobile phases, it was proposed an optimization algorithm based on a sixth-parameter retention model. This model considers simultaneously the contents of the main organic modifier and of the alkanol additive in the mobile phase as well as of the number of alkyl chain of the additive. This model is in fact a modification of a previously one derived in a recently published paper for the retention description of a mixture of purely hydrophobic alkylbenzenes under isocratic conditions with mobile phases containing alkanol additives. The effectiveness of the new retention model as well as the optimization algorithm was successfully applied to the separation of ten o-phthalaldehyde (OPA) derivatives of amino acids. Indeed, the new retention model exhibited an excellent prediction performance since the obtained overall predictive error between calculated and experimental times was only 2.8% for all isocratic runs by using a variety of mobile phase compositions containing any alkanol homologue even different than those used in the starting/fitting experiments. Moreover, a perfect resolution of the above amino acid mixture was achieved within only 7.4 min in the chromatogram recorded using the optimal mobile phase determined by means of the simple optimization algorithm proposed in this study.

  8. Frustration-induced protein intrinsic disorder

    NASA Astrophysics Data System (ADS)

    Matsushita, Katsuyoshi; Kikuchi, Macoto

    2013-03-01

    Spontaneous folding into a specific native structure is the most important property of protein to perform their biological functions within organisms. Spontaneous folding is understood on the basis of an energy landscape picture based on the minimum frustration principle. Therefore, frustration seemingly only leads to protein functional disorder. However, frustration has recently been suggested to have a function in allosteric regulation. Functional frustration has the possibility to be a key to our deeper understanding of protein function. To explore another functional frustration, we theoretically examined structural frustration, which is designed to induce intrinsic disorder of a protein and its function through the coupled folding and binding. We extended the Wako-Saitô-Muñoz-Eaton model to take into account a frustration effect. With the model, we analyzed the binding part of neuron-restrictive silencer factor and showed that designed structural frustration in it induces intrinsic disorder. Furthermore, we showed that the folding and the binding are cooperative in interacting with a target protein. The cooperativity enables an intrinsically disordered protein to exhibit a sharp switch-like folding response to binding chemical potential change. Through this switch-like response, the structural frustration may contribute to the regulation function of interprotein interaction of the intrinsically disordered protein.

  9. [Separation of bases, phenols and pharmaceuticals on ionic liquid-modified silica stationary phase with pure water as mobile phase].

    PubMed

    Wang, Xusheng; Qiu, Hongdeng; Liu, Xia; Jiang, Shengxiang

    2011-03-01

    N-methylimidazolium ionic liquid (IL) -modified silica was prepared with the reaction of 3-chloropropyl modified silica and N-methylimidazole using toluene as solvent. Based on the multiple interactions between N-methylimidazolium IL-modified silica and analytes such as hydrophobic interaction, electrostatic attraction, repulsion interaction, hydrogen-bonding, etc., the bases (cytosine, thymine, 2-aminopyrimidine and 6-chloroguanine), phenols (m-aminophenol, resorcinol and m-nitrophenol) and three pharmaceuticals (moroxydine hydrochloride, acyclovir and cephalexin hydrate) were separated successfully with only pure water as the mobile phase. These chromatographic separations are environmental friendly, economical and convenient, without any organic solvent or buffer additive. The retention mechanism of these samples on the stationary phase was also investigated.

  10. Steric Pressure among Membrane-Bound Polymers Opposes Lipid Phase Separation.

    PubMed

    Imam, Zachary I; Kenyon, Laura E; Carrillo, Adelita; Espinoza, Isai; Nagib, Fatema; Stachowiak, Jeanne C

    2016-04-19

    Lipid rafts are thought to be key organizers of membrane-protein complexes in cells. Many proteins that interact with rafts have bulky polymeric components such as intrinsically disordered protein domains and polysaccharide chains. Therefore, understanding the interaction between membrane domains and membrane-bound polymers provides insights into the roles rafts play in cells. Multiple studies have demonstrated that high concentrations of membrane-bound polymeric domains create significant lateral steric pressure at membrane surfaces. Furthermore, our recent work has shown that lateral steric pressure at membrane surfaces opposes the assembly of membrane domains. Building on these findings, here we report that membrane-bound polymers are potent suppressors of membrane phase separation, which can destabilize lipid domains with substantially greater efficiency than globular domains such as membrane-bound proteins. Specifically, we created giant vesicles with a ternary lipid composition, which separated into coexisting liquid ordered and disordered phases. Lipids with saturated tails and poly(ethylene glycol) (PEG) chains conjugated to their head groups were included at increasing molar concentrations. When these lipids were sparse on the membrane surface they partitioned to the liquid ordered phase. However, as they became more concentrated, the fraction of GUVs that were phase-separated decreased dramatically, ultimately yielding a population of homogeneous membrane vesicles. Experiments and physical modeling using compositions of increasing PEG molecular weight and lipid miscibility phase transition temperature demonstrate that longer polymers are the most efficient suppressors of membrane phase separation when the energetic barrier to lipid mixing is low. In contrast, as the miscibility transition temperature increases, longer polymers are more readily driven out of domains by the increased steric pressure. Therefore, the concentration of shorter polymers required

  11. Direct observation of mesoscopic phase separation in KxFeySe2 by scanning microwave microscopy

    NASA Astrophysics Data System (ADS)

    Maeda, Atsutaka; Takahashi, Hideyuki; Imai, Yoshinori

    2015-03-01

    KxFeySe2 is isostructural to 122-FeAs compounds. However, its electronic structure is unique among Fe-based superconductors in the sense that hole Fermi pocket is absent at the center of the Brillouin zone. Therefore, it is important to study this compounds in terms of the mechanism of superconductivity since some pairing (for example, s +/- -wave) needs the interaction between hole and electron Fermi pockets. However, the phase separation in this material makes studies using conventional macroscopic measurement techniques very difficult. Scanning near-field microwave microscope (SMM), which can measure local electric property of inhomogeneous conducting samples, should be a powerful tool. Recently we developed the combined instrument of STM and SMM with high sensitivity, and investigated the local electric property of KxFeySe2 (x = 0.8, y = 1.6 ~2, Tc = 31 K) using this scanning tunneling/microwave microscope. The characteristic pattern of mesoscopic phase separation of the metallic and the semiconducting phase was observed. From the comparison with previously reported SEM/EDS result we identified the metallic phase and the semiconducting phase as the minor Fe-rich phase and the major K2Fe4Se5 phase, respectively.

  12. Formation of Asymmetrical Structured Silica Controlled by a Phase Separation Process and Implication for Biosilicification

    PubMed Central

    Shi, Jia-Yuan; Yao, Qi-Zhi; Li, Xi-Ming; Zhou, Gen-Tao; Fu, Sheng-Quan

    2013-01-01

    Biogenetic silica displays intricate patterns assembling from nano- to microsize level and interesting non-spherical structures differentiating in specific directions. Several model systems have been proposed to explain the formation of biosilica nanostructures. Of them, phase separation based on the physicochemical properties of organic amines was considered to be responsible for the pattern formation of biosilica. In this paper, using tetraethyl orthosilicate (TEOS, Si(OCH2CH3)4) as silica precursor, phospholipid (PL) and dodecylamine (DA) were introduced to initiate phase separation of organic components and influence silica precipitation. Morphology, structure and composition of the mineralized products were characterized using a range of techniques including field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), infrared spectra (IR), and nitrogen physisorption. The results demonstrate that the phase separation process of the organic components leads to the formation of asymmetrically non-spherical silica structures, and the aspect ratios of the asymmetrical structures can be well controlled by varying the concentration of PL and DA. On the basis of the time-dependent experiments, a tentative mechanism is also proposed to illustrate the asymmetrical morphogenesis. Therefore, our results imply that in addition to explaining the hierarchical porous nanopatterning of biosilica, the phase separation process may also be responsible for the growth differentiation of siliceous structures in specific directions. Because organic amine (e.g., long-chair polyamines), phospholipids (e.g., silicalemma) and the phase separation process are associated with the biosilicification of diatoms, our results may provide a new insight into the mechanism of biosilicification. PMID:23585878

  13. Formation of asymmetrical structured silica controlled by a phase separation process and implication for biosilicification.

    PubMed

    Shi, Jia-Yuan; Yao, Qi-Zhi; Li, Xi-Ming; Zhou, Gen-Tao; Fu, Sheng-Quan

    2013-01-01

    Biogenetic silica displays intricate patterns assembling from nano- to microsize level and interesting non-spherical structures differentiating in specific directions. Several model systems have been proposed to explain the formation of biosilica nanostructures. Of them, phase separation based on the physicochemical properties of organic amines was considered to be responsible for the pattern formation of biosilica. In this paper, using tetraethyl orthosilicate (TEOS, Si(OCH2CH3)4) as silica precursor, phospholipid (PL) and dodecylamine (DA) were introduced to initiate phase separation of organic components and influence silica precipitation. Morphology, structure and composition of the mineralized products were characterized using a range of techniques including field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA), infrared spectra (IR), and nitrogen physisorption. The results demonstrate that the phase separation process of the organic components leads to the formation of asymmetrically non-spherical silica structures, and the aspect ratios of the asymmetrical structures can be well controlled by varying the concentration of PL and DA. On the basis of the time-dependent experiments, a tentative mechanism is also proposed to illustrate the asymmetrical morphogenesis. Therefore, our results imply that in addition to explaining the hierarchical porous nanopatterning of biosilica, the phase separation process may also be responsible for the growth differentiation of siliceous structures in specific directions. Because organic amine (e.g., long-chair polyamines), phospholipids (e.g., silicalemma) and the phase separation process are associated with the biosilicification of diatoms, our results may provide a new insight into the mechanism of biosilicification.

  14. Asymmetrical phase separation and gelation in binary mixtures of oppositely charged colloids

    NASA Astrophysics Data System (ADS)

    Zong, Yiwu; Yuan, Guangcui; Han, Charles C.

    2016-07-01

    Two types of colloidal particles, which are nearly the same in chemical composition but carry opposite surface charges, are mixed in water. Depending on the relative proportion of the oppositely charged particles, the process of aggregation leads to the formation of discrete clusters of various sizes in dilute dispersions, and to the development of particle gel networks in more concentrated systems. Due to the significant difference in the absolute values of surface charges (negative particle: -48 mV, positive particle: +24 mV), the phase separation and the gelation behaviors are asymmetric with respect to the mixing ratio. Mixtures with excess negative particles are more stable, while mixtures with excess positive particles are easily affected by phase separation. The hetero-aggregation triggered by the addition of microscopically large macro-ions is similar to what is often observed in a mono-component charged colloidal system, i.e., phase separation occurs through addition of small electrolyte ions. Within the concentration region investigated here, it is clear that the gel line is buried inside the phase separation region. Gelation occurs only when the number and size of the clusters are large and big enough to connect up into a space-spanning network. Our results indicate that, in this binary mixture of oppositely charged colloids, although the interaction between unlike species is attractive and that between like species is repulsive, the onset of gelation is in fact governed by the equilibrium phase separation, as in the case of purely attractive systems with short-range isotropic interaction.

  15. Asymmetrical phase separation and gelation in binary mixtures of oppositely charged colloids.

    PubMed

    Zong, Yiwu; Yuan, Guangcui; Han, Charles C

    2016-07-07

    Two types of colloidal particles, which are nearly the same in chemical composition but carry opposite surface charges, are mixed in water. Depending on the relative proportion of the oppositely charged particles, the process of aggregation leads to the formation of discrete clusters of various sizes in dilute dispersions, and to the development of particle gel networks in more concentrated systems. Due to the significant difference in the absolute values of surface charges (negative particle: -48 mV, positive particle: +24 mV), the phase separation and the gelation behaviors are asymmetric with respect to the mixing ratio. Mixtures with excess negative particles are more stable, while mixtures with excess positive particles are easily affected by phase separation. The hetero-aggregation triggered by the addition of microscopically large macro-ions is similar to what is often observed in a mono-component charged colloidal system, i.e., phase separation occurs through addition of small electrolyte ions. Within the concentration region investigated here, it is clear that the gel line is buried inside the phase separation region. Gelation occurs only when the number and size of the clusters are large and big enough to connect up into a space-spanning network. Our results indicate that, in this binary mixture of oppositely charged colloids, although the interaction between unlike species is attractive and that between like species is repulsive, the onset of gelation is in fact governed by the equilibrium phase separation, as in the case of purely attractive systems with short-range isotropic interaction.

  16. Phase separation of polymer mixtures induced by light and heat: a comparative study by light scattering

    NASA Astrophysics Data System (ADS)

    Ochi, Yuki; Kawakubo, Rie; Van-Pham, Dan-Thuy; Kitamura, Yuki; Nakanishi, Hideyuki; Norisuye, Tomohisa; Tran-Cong-Miyata, Qui

    2015-12-01

    Phase separation of binary blends composed of a polystyrene derivative (PS) and poly (vinyl methyl ether) (PVME) with a lower critical solution temperature (LCST) was experimentally induced by two different methods: heating and UV light irradiation. Using laser light scattering combined with the temperature jump (T-jump) technique, it was demonstrated that in the case of heating, the mixture undergoes phase separation via the nucleation-and-growth (NG) and the spinodal decomposition (SN) processes under shallow and deep quenches, respectively. Particularly, the crossover from the spinodal decomposition to the nucleation-and-growth process was observed at long time under a deep T-jump by light-scattering experiments. On the other hand, in the photo-crosslink case, the PS/PVME blends undergo a nucleation-and-growth process upon irradiation with weak light intensity, whereas the mixture exhibits the spinodal decomposition under irradiation with strong light intensity. From the analysis of the light-scattering data obtained for the blends under the photo-crosslink, the kinetic data reveal the suppression of morphologies having large characteristic length scales. This feature clearly differs from the phase separation induced by heating where no mode-suppression process was observed. It was also found that distribution of the characteristic length scales (the regularity) of the morphology becomes narrow as the phase separation proceeds for reacting blends, whereas it becomes broader as the phase separation proceeds by heating, revealing the important roles of reaction in the suppression of fluctuations with long wavelengths. These experimental results establish a method to control the length scales and the regularity of the morphology of polymer blends by chemical reaction.

  17. Phase separation behavior of egg yolk suspensions after anionic polysaccharides addition.

    PubMed

    Navidghasemizad, Sahar; Temelli, Feral; Wu, Jianping

    2015-03-06

    The objectives of this study were to understand the interactions between three anionic polysaccharides (gum arabic, xanthan gum and ι-carrageenan) and egg yolk at pH 3, 5, 6, 8, 10 and possible phase separation behavior. Zeta potential of egg yolk was not affected by gum arabic addition while it became more negative at pH 5 after xanthan gum and ι-carrageenan addition. The particle size of ι-carrageenan yolk suspension was considerably higher than the other polysaccharide yolk suspensions at pH below 6 but was dramatically decreased at alkaline pH. Most polysaccharide yolk suspensions formed either a biphasic or a monophasic system, whereas three distinct phases were observed for xanthan gum yolk suspension at pH 6. Protein profile analysis of the lipid-rich cream phase obtained from xanthan gum added yolk showed similarities to apoproteins from low density lipoproteins (LDL) of egg yolk. Microscopy analysis indicated the co-presence of xanthan gum and LDL in the creamy phase, within a network formed by xanthan gum. It was suggested that electrostatic and hydrophobic interactions between the egg yolk and xanthan gum as well as xanthan gum's rheological properties could be responsible for the unique phase separation observed in the study. The findings of this study can form the basis for future studies to develop a new method to separate LDL from egg yolk.

  18. Extraordinary phase separation and segregation in vent fluids from the southern East Pacific Rise

    USGS Publications Warehouse

    Von Damm, Karen L.; Lilley, M.D.; Shanks, Wayne C.; Brockington, M.; Bray, A.M.; O'Grady, K. M.; Olson, E.; Graham, A.; Proskurowski, G.

    2003-01-01

    The discovery of Brandon vent on the southern East Pacific Rise is providing new insights into the controls on midocean ridge hydrothermal vent fluid chemistry. The physical conditions at the time ofsampling (287 bar and 405??C) place the Brandon fluids very close to the critical point of seawater (298 bar and 407??C). This permits in situ study of the effects of near criticalphenomena, which are interpreted to be the primary cause of enhanced transition metal transport in these fluids. Of the five orifices on Brandon sampled, three were venting fluids with less than seawater chlorinity, and two were venting fluids with greater than seawater chlorinity. The liquid phase orifices contain 1.6-1.9 times the chloride content of the vapors. Most other elements, excluding the gases, have this same ratio demonstrating the conservative nature of phase separation and the lack of subsequent water-rock interaction. The vapor and liquid phases vent at the same time from orifices within meters of each other on the Brandon structure. Variations in fluid compositions occur on a time scale of minutes. Our interpretation is that phase separation and segregation must be occurring 'real time' within the sulfide structure itself. Fluids from Brandon therefore provide an unique opportunity to understand in situ phase separation without the overprinting of continued water-rock interaction with the oceanic crust, as well as critical phenomena. ?? 2002 Elsevier Science B.V. All rights reserved.

  19. Separation of selected stable isotopes by liquid-phase thermal diffusion and by chemical exchange

    NASA Astrophysics Data System (ADS)

    Rutherford, W. M.; Jepson, B. E.; Michaels, E. D.

    Useful applications of enriched stable nuclides are unduly restricted by high cost and limited availability. Recent research on liquid phase thermal diffusion (LTD) has resulted in practical processes for separating S34, CL35, and CL37 in significant quantities (100 to 500 g/yr) at costs much lower than those associated with the electromagnetic (Calutron) process. The separation of the isotopes of bromine by LTD is now in progress and BR79 is being produced in relatively simple equivalent at a rate on the order of 0.5 g/day. The results of recent measurements show that the isotopes of Zn can be separated by LTD of zinc alkyls. The isotopes of calcium can be separated by LTD and by chemical exchange. The LTD process is based on the use of aqueous Ca(NO3)2 as a working fluid.

  20. Reversed-phase liquid chromatographic separation and simultaneous profiling of steroidal glycoalkaloids and their aglycones.

    PubMed

    Kuronen, P; Väänänen, T; Pehu, E

    1999-11-19

    Improved and simplified reversed-phase liquid chromatographic conditions for the separation and simultaneous profiling of both steroidal glycoalkaloids and their aglycones, having solanidane- or spirosolane-type structures, are described. The most reproducible retention behavior for these ionizable compounds on C18 columns was achieved under isocratic and gradient elution conditions using acetonitrile in combination with triethylammonium phosphate buffer at pH 3.0, when basic functional groups of solutes and silanol groups on the silica are fully protonated minimizing ionic interactions. Gradient elution was the only feasible approach for the simultaneous separation of steroidal glycoalkaloids and their aglycones. A Zorbax SB C18 column, specially designed for low-pH separations, showed good performance in critical separations. The impurities of the commercial tomatine and tomatidine standards were studied and confirmed using mass spectrometric, liquid chromatographic and thin-layer chromatographic methods.

  1. Spin jam induced by quantum fluctuations in a frustrated magnet

    PubMed Central

    Yang, Junjie; Samarakoon, Anjana; Dissanayake, Sachith; Ueda, Hiroaki; Klich, Israel; Iida, Kazuki; Pajerowski, Daniel; Butch, Nicholas P.; Huang, Q.; Copley, John R. D.; Lee, Seung-Hun

    2015-01-01

    Since the discovery of spin glasses in dilute magnetic systems, their study has been largely focused on understanding randomness and defects as the driving mechanism. The same paradigm has also been applied to explain glassy states found in dense frustrated systems. Recently, however, it has been theoretically suggested that different mechanisms, such as quantum fluctuations and topological features, may induce glassy states in defect-free spin systems, far from the conventional dilute limit. Here we report experimental evidence for existence of a glassy state, which we call a spin jam, in the vicinity of the clean limit of a frustrated magnet, which is insensitive to a low concentration of defects. We have studied the effect of impurities on SrCr9pGa12-9pO19 [SCGO(p)], a highly frustrated magnet, in which the magnetic Cr3+ (s = 3/2) ions form a quasi-2D triangular system of bipyramids. Our experimental data show that as the nonmagnetic Ga3+ impurity concentration is changed, there are two distinct phases of glassiness: an exotic glassy state, which we call a spin jam, for the high magnetic concentration region (p>0.8) and a cluster spin glass for lower magnetic concentration (p<0.8). This observation indicates that a spin jam is a unique vantage point from which the class of glassy states of dense frustrated magnets can be understood. PMID:26324917

  2. Spin jam induced by quantum fluctuations in a frustrated magnet.

    PubMed

    Yang, Junjie; Samarakoon, Anjana; Dissanayake, Sachith; Ueda, Hiroaki; Klich, Israel; Iida, Kazuki; Pajerowski, Daniel; Butch, Nicholas P; Huang, Q; Copley, John R D; Lee, Seung-Hun

    2015-09-15

    Since the discovery of spin glasses in dilute magnetic systems, their study has been largely focused on understanding randomness and defects as the driving mechanism. The same paradigm has also been applied to explain glassy states found in dense frustrated systems. Recently, however, it has been theoretically suggested that different mechanisms, such as quantum fluctuations and topological features, may induce glassy states in defect-free spin systems, far from the conventional dilute limit. Here we report experimental evidence for existence of a glassy state, which we call a spin jam, in the vicinity of the clean limit of a frustrated magnet, which is insensitive to a low concentration of defects. We have studied the effect of impurities on SrCr9pGa12-9pO19 [SCGO(p)], a highly frustrated magnet, in which the magnetic Cr(3+) (s = 3/2) ions form a quasi-2D triangular system of bipyramids. Our experimental data show that as the nonmagnetic Ga(3+) impurity concentration is changed, there are two distinct phases of glassiness: an exotic glassy state, which we call a spin jam, for the high magnetic concentration region (p > 0.8) and a cluster spin glass for lower magnetic concentration (p < 0.8). This observation indicates that a spin jam is a unique vantage point from which the class of glassy states of dense frustrated magnets can be understood.

  3. Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

    SciTech Connect

    Zhang, Kai; Du, Kai; Liu, Hao; Zhang, X. -G.; Lan, Fanli; Lin, Hanxuan; Wei, Wengang; Zhu, Yinyan; Kou, Yunfang; Shao, Jian; Niu, Jiebin; Wang, Wenbin; Wu, Ruqian; Yin, Lifeng; Plummer, E. W.; Shen, Jian

    2015-07-20

    The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. In this paper, by fabricating antidot arrays in La0.325Pr0.3Ca0.375MnO3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasing magnetic field. Finally, this study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.

  4. Comment on "Phase separation in a two-species Bose mixture"

    NASA Astrophysics Data System (ADS)

    Zhan, Fei; McCulloch, Ian P.

    2014-05-01

    In an article in 2007, Mishra et al. [Phys. Rev. A 76, 013604 (2007), 10.1103/PhysRevA.76.013604] investigated the two-component Bose-Hubbard model using the numerical density-matrix renormalization-group procedure. In the regime of interspecies repulsion Uab larger than the intraspecies repulsion U, they found a transition from a uniform miscible phase to phase separation occurring at a finite value of U, e.g., at around U =1.3 for Δ =Uab/U =1.05 and ρa=ρb=1/2. In this Comment, we show that this result is not correct, and in fact, the two-component Bose-Hubbard model is unstable to phase separation for any Uab>U >0.

  5. Supercooling transition in phase separated manganite thin films: An electrical transport study

    SciTech Connect

    Singh, Sandeep; Kumar, Pawan; Siwach, P. K.; Singh, H. K.; Tyagi, Pawan Kumar

    2014-05-26

    The impact of variation in the relative fractions of the ferromagnetic metallic and antiferromagnetic/charge ordered insulator phases on the supercooling/superheating transition in strongly phase separated system, La{sub 5/8−y}Pr{sub y}Ca{sub 3/8}MnO{sub 3} (y ≈ 0.4), has been studied employing magnetotransport measurements. Our study clearly shows that the supercooling transition temperature is non-unique and strongly depends on the magneto-thermodynamic path through which the low temperature state is accessed. In contrast, the superheating transition temperature remains constant. The thermo-magnetic hysteresis, the separation of the two transitions and the associated resistivity, all are functions of the relative fraction of the coexisting phases.

  6. Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

    PubMed Central

    Zhang, Kai; Du, Kai; Liu, Hao; Zhang, X.-G.; Lan, Fanli; Lin, Hanxuan; Wei, Wengang; Zhu, Yinyan; Kou, Yunfang; Shao, Jian; Niu, Jiebin; Wang, Wenbin; Wu, Ruqian; Yin, Lifeng; Plummer, E. W.; Shen, Jian

    2015-01-01

    The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. By fabricating antidot arrays in La0.325Pr0.3Ca0.375MnO3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasing magnetic field. This study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field. PMID:26195791

  7. Chemical ordering suppresses large-scale electronic phase separation in doped manganites

    NASA Astrophysics Data System (ADS)

    Zhu, Yinyan; Du, Kai; Niu, Jiebin; Lin, Lingfang; Wei, Wengang; Liu, Hao; Lin, Hanxuan; Zhang, Kai; Yang, Tieying; Kou, Yunfang; Shao, Jian; Gao, Xingyu; Xu, Xiaoshan; Wu, Xiaoshan; Dong, Shuai; Yin, Lifeng; Shen, Jian

    2016-04-01

    For strongly correlated oxides, it has been a long-standing issue regarding the role of the chemical ordering of the dopants on the physical properties. Here, using unit cell by unit cell superlattice growth technique, we determine the role of chemical ordering of the Pr dopant in a colossal magnetoresistant (La1-yPry)1-xCaxMnO3 (LPCMO) system, which has been well known for its large length-scale electronic phase separation phenomena. Our experimental results show that the chemical ordering of Pr leads to marked reduction of the length scale of electronic phase separations. Moreover, compared with the conventional Pr-disordered LPCMO system, the Pr-ordered LPCMO system has a metal-insulator transition that is ~100 K higher because the ferromagnetic metallic phase is more dominant at all temperatures below the Curie temperature.

  8. Vacancy-mediated fcc/bcc phase separation in Fe1-xNix ultrathin films

    DOE PAGES

    Mentes, T. O.; Stojic, N.; Vescovo, E.; ...

    2016-08-01

    The phase separation occurring in Fe-Ni thin lms near the Invar composition is studied by using high resolution spectromicroscopy techniques and density functional theory calculations. Annealed at temperatures around 300 C, Fe0.70Ni0.30 lms on W(110) break into micron-sized bcc and fcc domains with compositions in agreement with the bulk Fe-Ni phase diagram. Ni is found to be the di using species in forming the chemical heterogeneity. The experimentally-determined energy barrier of 1.59 0.09 eV is identi ed as the vacancy formation energy via density functional theory calculations. Thus, the principal role of the surface in the phase separation process ismore » attributed to vacancy creation without interstitials.« less

  9. Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

    DOE PAGES

    Zhang, Kai; Du, Kai; Liu, Hao; ...

    2015-07-20

    The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. In this paper, by fabricating antidot arrays in La0.325Pr0.3Ca0.375MnO3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition with decreasing temperature or increasingmore » magnetic field. Finally, this study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.« less

  10. Separation of nuclei representing different phases of the growth cycle from unsynchronized mammalian cell cultures.

    PubMed

    McBride, O W; Peterson, E A

    1970-10-01

    Nuclei have been isolated from unsynchronized cultures of Chinese hamster fibroblasts after varying intervals of growth following the incorporation of thymidine (-3)H for 20 min. These nuclei were fractionated by unit gravity sedimentation in a stabilizing density gradient of sucrose, and fractions were analyzed for the concentration of nuclei, DNA, and radioactivity. A more rapidly sedimenting population of nuclei in the G(2) phase of the cell cycle was separated from a group of nuclei in the G(1) phase, and nuclei in progressive stages of DNA synthesis (S phase) were distributed between these two regions. The fractionation of intact cells by sedimentation according to their position in the cell cycle was found to be less satisfactory than the corresponding separation of nuclei. This probably results from the continuous accumulation of mass within individual cells throughout the entire cell cycle, whereas most of the mass of a nucleus is replicated during a relatively narrow interval of the total cell cycle.

  11. Long-term stability of phase-separated half-Heusler compounds.

    PubMed

    Krez, J; Balke, B; Ouardi, S; Selle, S; Höche, T; Felser, C; Hermes, W; Schwind, M

    2015-11-28

    Half-Heusler (HH) compounds have shown high figure of merit up to 1.5. Here, we address the long-term stability of n- and p-type HH materials. For this purpose, we investigated HH materials based on the Ti0.3Zr0.35Hf0.35NiSn-system after 500 cycles (1700 h) from 373 to 873 K. Both compounds exhibit a maximum Seebeck coefficient of |α|≈ 210 μV K(-1) and a phase separation into two HH phases. The dendritic microstructure is temperature resistant and upon cycling the changes in the microstructure are so marginal that the low thermal conductivity values (κ < 4 W m(-1) K(-1)) could be maintained. Our results emphasize that phase-separated HH compounds are suitable low cost materials and can lead to enhanced thermoelectric efficiencies beyond the set benchmark for industrial applications.

  12. Modeling the phase separation in binary lipid membrane under externally imposed oscillatory shear flow.

    PubMed

    Chen, Xiao-Bo; Niu, Li-Sha; Shi, Hui-Ji

    2008-09-01

    By adding external velocity terms, the two-dimensional time-dependent Ginzburg-Landau (TDGL) equations are modified. Based on this, the phase separation in binary lipid membrane under externally imposed oscillatory shear flow is numerically modeled employing the Cell Dynamical System (CDS) approach. Considering shear flows with different frequencies and amplitudes, several aspects of such a phase evolving process are studied. Firstly, visualized results are shown via snapshot figures of the membrane shape. And then, the simulated scattering patterns at typical moments are presented. Furthermore, in order to more quantitatively discuss this phase-separation process, the time growth laws of the characteristic domain sizes in both directions parallel and perpendicular to the flow are investigated for each case. Finally, the peculiar rheological properties of such binary lipid membrane system have been discussed, mainly the normal stress difference and the viscoelastic complex shear moduli.

  13. Vacancy-mediated fcc/bcc phase separation in Fe1 -xNix ultrathin films

    NASA Astrophysics Data System (ADS)

    Menteş, T. O.; Stojić, N.; Vescovo, E.; Ablett, J. M.; Niño, M. A.; Locatelli, A.

    2016-08-01

    The phase separation occurring in Fe-Ni thin films near the Invar composition is studied by using high-resolution spectromicroscopy techniques and density functional theory calculations. Annealed at temperatures around 300 ∘C ,Fe0.70Ni0.30 films on W(110) break into micron-sized bcc and fcc domains with compositions in agreement with the bulk Fe-Ni phase diagram. Ni is found to be the diffusing species in forming the chemical heterogeneity. The experimentally determined energy barrier of 1.59 ±0.09 eV is identified as the vacancy formation energy via density functional theory calculations. Thus, the principal role of the surface in the phase separation process is attributed to vacancy creation without interstitials.

  14. Chemical ordering suppresses large-scale electronic phase separation in doped manganites

    PubMed Central

    Zhu, Yinyan; Du, Kai; Niu, Jiebin; Lin, Lingfang; Wei, Wengang; Liu, Hao; Lin, Hanxuan; Zhang, Kai; Yang, Tieying; Kou, Yunfang; Shao, Jian; Gao, Xingyu; Xu, Xiaoshan; Wu, Xiaoshan; Dong, Shuai; Yin, Lifeng; Shen, Jian

    2016-01-01

    For strongly correlated oxides, it has been a long-standing issue regarding the role of the chemical ordering of the dopants on the physical properties. Here, using unit cell by unit cell superlattice growth technique, we determine the role of chemical ordering of the Pr dopant in a colossal magnetoresistant (La1−yPry)1−xCaxMnO3 (LPCMO) system, which has been well known for its large length-scale electronic phase separation phenomena. Our experimental results show that the chemical ordering of Pr leads to marked reduction of the length scale of electronic phase separations. Moreover, compared with the conventional Pr-disordered LPCMO system, the Pr-ordered LPCMO system has a metal–insulator transition that is ∼100 K higher because the ferromagnetic metallic phase is more dominant at all temperatures below the Curie temperature. PMID:27053071

  15. An improved stochastic separated flow model for turbulent two-phase flow

    NASA Astrophysics Data System (ADS)

    Chan, C. K.; Zhang, H. Q.; Lau, K. S.

    An improved stochastic separated flow model is proposed to obtain reasonable statistical characteristics of a two-phase flow. Effects of the history of a particle and its current trajectory position on the mean-square fluctuating velocity of the dispersed phase are continuously considered in this model. Comparing with the conventional model, results using the improved model are more reasonable and can also be obtained more easily. Furthermore, the improved model requires less computational particles for simulating dispersed-phase turbulence at the beginning of the stochastic trajectory. In this paper, an application in turbulent two-phase flow of planar mixing layer is carried out. Numerical results including velocity, mean-square fluctuating velocity, particle number density and pdf of fluctuation velocity of dispersed phase are shown to compare well with experimental data.

  16. Real-Time Volumetric Phase Monitoring: Advancing Chemical Analysis by Countercurrent Separation.

    PubMed

    Pauli, Guido F; Pro, Samuel M; Chadwick, Lucas R; Burdick, Thomas; Pro, Luke; Friedl, Warren; Novak, Nick; Maltby, John; Qiu, Feng; Friesen, J Brent

    2015-07-21

    Countercurrent separation (CCS) utilizes the differential partitioning behavior of analytes between two immiscible liquid phases. We introduce the first platform ("CherryOne") capable of real-time monitoring, metering, and control of the dynamic liquid-liquid CCS process. Automated phase monitoring and volumetrics are made possible with an array of sensors, including the new permittivity-based phase metering apparatus (PMA). Volumetric data for each liquid phase are converted into a dynamic real-time display of stationary phase retention (Sf) and eluent partition coefficients (K), which represent critical parameters of CCS reproducibility. When coupled with the elution-extrusion operational mode (EECCC), automated Sf and K determination empowers untargeted and targeted applications ranging from metabolomic analysis to preparative purifications.

  17. Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions

    NASA Astrophysics Data System (ADS)

    Zawadowicz, M. A.; Proud, S. R.; Seppalainen, S. S.; Cziczo, D. J.

    2015-08-01

    Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead, they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR (Fourier transform infrared) spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance and, therefore, particles prepared in this study should mimic atmospheric mixed-phase aerosol particles. Some results of this study tend to be in agreement with previous microscopy experiments, but others, such as phase separation properties of 1,2,6-hexanetriol, do not agree with previous work. Because the particles studied in this experiment are of a smaller size than those used in microscopy studies, the discrepancies found could be a size-related effect.

  18. Hygroscopic and phase separation properties of ammonium sulfate/organic/water ternary solutions

    NASA Astrophysics Data System (ADS)

    Zawadowicz, M. A.; Proud, S. R.; Seppalainen, S. S.; Cziczo, D. J.

    2015-03-01

    Atmospheric aerosol particles are often partially or completely composed of inorganic salts, such as ammonium sulfate and sodium chloride, and therefore exhibit hygroscopic properties. Many inorganic salts have well-defined deliquescence and efflorescence points at which they take up and lose water, respectively. Deliquescence and efflorescence of simple inorganic salt particles have been investigated by a variety of methods, such as IR spectroscopy, tandem mobility analysis and electrodynamic balance. Field measurements have shown that atmospheric aerosols are not typically pure inorganic salt, instead they often also contain organic species. There is ample evidence from laboratory studies that suggests that mixed particles exist in a phase-separated state, with an aqueous inorganic core and organic shell. Although phase separation has not been measured in situ, there is no reason it would not also take place in the atmosphere. Many recent studies have focused on microscopy techniques that require deposition of the aerosol on a glass slide, possibly changing its surface properties. Here, we investigate the deliquescence and efflorescence points, phase separation and ability to exchange gas-phase components of mixed organic and inorganic aerosol using a flow tube coupled with FTIR spectroscopy. Ammonium sulfate aerosol mixed with organic polyols with different O : C ratios, including 1,4-butanediol, glycerol, 1,2,6-hexanetriol, 1,2-hexanediol, and 1,5-pentanediol have been investigated. Those constituents correspond to materials found in the atmosphere in great abundance, and therefore, particles prepared in this study should mimic atmospheric mixed phase aerosol particles. The results of this study tend to be in agreement with previous microscopy experiments, with several key differences, which possibly reveal a size-dependent effect on phase separation in organic/inorganic aerosol particles.

  19. Nanoscale control over phase separation in conjugated polymer blends using mesoporous silica spheres.

    PubMed

    Kelly, Timothy L; Yano, Kazuhisa; Wolf, Michael O

    2010-01-05

    A method of preparing blended conjugated polymer microparticles using mesoporous silica spheres is described. Poly(3,4-ethylenedioxythiophene) (PEDOT) was blended with poly(furfuryl alcohol) (PFA) by a sequential infiltration-polymerization approach. The materials were evaluated by both scanning and transmission electron microscopy and are shown to retain the overall spherical structure of the silica template. The filling of the mesopores and the polymer distribution within individual particles were determined by a combination of energy-dispersive X-ray microanalysis, X-ray photoelectron spectroscopy, and nitrogen adsorption. The results suggest that when PEDOT is added to the silica host, followed by PFA, the phase separation of the two immiscible polymers is constrained by the dimensions of the silica mesopores, ensuring nanoscale contact between the two phases. The silica template can be removed by etching with 25% hydrofluoric acid, leaving behind a blended polymer microparticle. The etched microparticles exhibit macroporous morphologies different from that of pure PEDOT particles prepared by a similar route. The blended microparticles also appear to undergo limited phase separation; no evidence for distinct polymer domains was observed. Conductivity measurements indicate that the blended particles are above the percolation threshold and support the conclusion that the phase domains are extremely small. Importantly, when PFA is added to the host first, followed by PEDOT, there is a striking difference to the final composition and morphology of the particles. This reversal of the blending order results in a more amorphous, phase-separated material. These results demonstrate the preparation of conjugated polymer blends with engineered nanoscale phase separation and may allow for future improvements in organic device architecture and performance.

  20. Langmuir-Blodgett films of fluorinated glycolipids and polymerizable lipids and their phase separating behavior.

    PubMed

    Scheibe, Patrick; Schoenhentz, Jerome; Platen, Tobias; Hoffmann-Röder, Anja; Zentel, Rudolf

    2010-12-07

    This paper describes the phase separating behavior of Langmuir monolayers from mixtures of different lipids that (i) either carry already a glycopeptide recognition site or can be easily modified to carry one and (ii) polymerizable lipids. To ensure demixing during compression, we used fluorinated lipids for the biological headgroups and hydrocarbon based lipids as polymerizable lipids. As a representative for a lipid monomer, which can be polymerized in the hydrophilic headgroup, a methacrylic monomer was used. As a monomer, which can be polymerized in the hydrophobic tail, a lipid with a diacetylene unit was used (pentacosadiynoic acid, PDA). The fluorinated lipids were on the one hand a perfluorinated lipid with three chains and on the other hand a partially fluorinated lipid with a T(N)-antigen headgroup. The macroscopic phase separation was observed by Brewster angle microscopy, whereas the phase separation on the nanoscale level was observed by atomic force microscopy. It turned out that all lipid mixtures showed (at least) a partial miscibility of the hydrocarbon compounds in the fluorinated compounds. This is positive for pattern formation, as it allows the formation of small demixed 2D patterned structures during crystallization from the homogeneous phase. For miscibility especially a liquid analogue phase proved to be advantageous. As lipid 3 with three fluorinated lipid chains (very stable monolayer) is miscible with the polymerizable lipids 1 and 2, it was mostly used for further investigations. For all three lipid mixtures, a phase separation on both the micrometer and the nanometer level was observed. The size of the crystalline domains could be controlled not only by varying the surface pressure but also by varying the molar composition of the mixtures. Furthermore, we showed that the binary mixture can be stabilized via UV polymerization. After polymerization and subsequent expansion of the barriers, the locked-in polymerized structures are stable

  1. DESIGN AND DEVELOPMENT OF GAS-LIQUID CYLINDRICAL CYCLONE COMPACT SEPARATORS FOR THREE-PHASE FLOW

    SciTech Connect

    Dr. Ram S. Mohan; Dr. Ovadia Shoham

    2000-04-28

    The objective of this five-year project (October, 1997-September, 2002) is to expand the current research activities of Tulsa University Separation Technology Projects (TUSTP) to multiphase oil/water/gas separation. This project will be executed in two phases. Phase I (1997-2000) will focus on the investigations of the complex multiphase hydrodynamic flow behavior in a three-phase Gas-Liquid Cylindrical Cyclone (GLCC{copyright}) Separator. The activities of this phase will include the development of a mechanistic model, a computational fluid dynamics (CFD) simulator, and detailed experimentation on the three-phase GLCC{copyright}. The experimental and CFD simulation results will be suitably integrated with the mechanistic model. In Phase II (2000-2002), the developed GLCC{copyright} separator will be tested under high pressure and real crudes conditions. This is crucial for validating the GLCC{copyright} design for field application and facilitating easy and rapid technology deployment. Design criteria for industrial applications will be developed based on these results and will be incorporated into the mechanistic model by TUSTP. This report presents a brief overview of the activities and tasks accomplished during the first half year (October 1, 1999-March 31, 2000) of the budget period (October 1, 1999-September 30, 2000). The total tasks of the budget period are given initially, followed by the technical and scientific results achieved till date. The report concludes with a detailed description of the plans for the conduct of the project for the second half year (April 1, 2000-September 30, 2000) of the current budget period.

  2. Emergent incommensurate correlations in frustrated ferromagnetic spin-1 chains

    NASA Astrophysics Data System (ADS)

    Lee, Hyeong Jun; Choi, MooYoung; Jeon, Gun Sang

    2017-01-01

    We study frustrated ferromagnetic spin-1 chains, where the ferromagnetic nearest-neighbor coupling competes with the antiferromagnetic next-nearest-neighbor coupling. We use the density-matrix renormalization group to obtain the ground states. Through the analysis of spin-spin correlations we identify the double Haldane phase as well as the ferromagnetic phase. It is shown that the ferromagnetic coupling leads to incommensurate correlations in the double Haldane phase. Such short-range correlations transform continuously into the ferromagnetic instability at the transition to the ferromagnetic phase. We also compare the results with the spin-1/2 and classical spin systems and discuss the string orders in the system.

  3. Exploration of Artificial Frustrated Magnets

    SciTech Connect

    Samarth, Nitin; Schiffer, Peter; Crespi, Vincent

    2015-02-17

    This program encompasses experimental and theoretical studies of arrays of nanometer-scale magnets known as “artificial frustrated magnets”. These magnets are small and closely spaced, so that their behavior as a collective group is complex and reveals insights into how such collections of interacting objects behave as a group. In particular, the placement of the magnets is such that the interactions between them are “frustrated”, in that they compete with each other. These systems are analogs to a class of magnetic materials in which the lattice geometry frustrates interactions between individual atomic moments, and in which a wide range of novel physical phenomena have been recently observed. The advantage to studying the arrays is that they are both designable and resolvable: i.e., the experiments can control all aspects of the array geometry, and can also observe how individual elements of the arrays behave. This research program demonstrated a number of phenomena including the role of multiple collective interactions, the feasibility of using systems with their magnetism aligned perpendicular to the plane of the array, the importance of disorder in the arrays, and the possibility of using high temperatures to adjust the magnet orientations. All of these phenomena, and others explored in this program, add to the body of knowledge around collective magnetic behavior and magnetism in general. Aside from building scientific knowledge in an important technological area, with relevance to computing and memory, the program also gave critical support to the education of students working on the experiments.

  4. Stability and Oil Migration of Oil-in-Water Emulsions Emulsified by Phase-Separating Biopolymer Mixtures.

    PubMed

    Yang, Nan; Mao, Peng; Lv, Ruihe; Zhang, Ke; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O

    2016-08-01

    Oil-in-water (O/W) emulsions with varying concentration of oil phase, medium-chain triglyceride (MCT), were prepared using phase-separating gum arabic (GA)/sugar beet pectin (SBP) mixture as an emulsifier. Stability of the emulsions including emulsion phase separation, droplet size change, and oil migration were investigated by means of visual observation, droplet size analysis, oil partition analysis, backscattering of light, and interfacial tension measurement. It was found that in the emulsions prepared with 4.0% GA/1.0% SBP, when the concentration of MCT was greater than 2.0%, emulsion phase separation was not observed and the emulsions were stable with droplet size unchanged during storage. This result proves the emulsification ability of phase-separating biopolymer mixtures and their potential usage as emulsifiers to prepare O/W emulsion. However, when the concentration of MCT was equal or less than 2.0%, emulsion phase separation occurred after preparation resulting in an upper SBP-rich phase and a lower GA-rich phase. The droplet size increased in the upper phase whereas decreased slightly in the lower phase with time, compared to the freshly prepared emulsions. During storage, the oil droplets exhibited a complex migration process: first moving to the SBP-rich phase, then to the GA-rich phase and finally gathering at the interface between the two phases. The mechanisms of the emulsion stability and oil migration in the phase-separated emulsions were discussed.

  5. Separation of basic compounds by capillary electrochromatography on an X-Terra RP18 stationary phase.

    PubMed

    Valette, J C; Bizet, A C; Demesmay, C; Rocca, J L; Verdon, E

    2004-09-17

    In this work we demonstrate that the X-Terra RP18 stationary phase, specially designed for the analysis of basic compounds in liquid chromatography, may be successfully used in capillary electrochromatography. Although this packing material does not afford a sufficient electroosmotic flow with classical hydro-organic mobile phases, the addition of a surfactant that adsorbs onto the stationary phase allows to generate a sustainable electroosmosis flow (EOF), the direction of which depends on the charge of the surfactant. The way of manipulating the electroosmotic flow is described (nature and concentration of the added surfactant, proportion of the organic modifier in the mobile phase, pH). It is then demonstrated that high efficiencies can be reached with this packing material (up to 220,000 plates/m with a mean diameter particles of 3.5 microm) when it is operated at high linear velocities. Then the separations of different classes of compounds such as amphenicol antibiotics, macrolide antibiotics or basic test solutes with mobile phases with pH up to 10.8 are described. The influence of the addition of sodium dodcylsulfate (SDS) to the mobile phase on the retention is described and the selectivity of the X-Terra RP18 stationary phase is compared to that of a more traditional phase, i.e. Hypersil C18 stationary phase with SDS added to the mobile phase. However, it is shown that a good repeatability of the retention factors can only be obtained when the ionization of the compounds is totally suppressed since electrolysis of the buffered hydro-organic mobile phase occurs in the buffer reservoirs leading to a variation of the mobile phase pH and consequently to a modification of the ionization degree of the solutes having their pKa close to the mobile phase pH.

  6. Graphitic carbon nitride as high-resolution stationary phase for gas chromatographic separations.

    PubMed

    Zheng, Yunzhong; Qi, Meiling; Fu, Ruonong

    2016-07-08

    This work presents the first example of utilization of graphitic carbon nitride (g-C3N4) as stationary phase for capillary gas chromatographic (GC) separations. The statically coated g-C3N4 column showed the column efficiencies of 3760 plates/m and weak polarity. Its resolving capability and retention behaviours were investigated by using the Grob test mixture, and mixtures of diverse types of analytes, and structural and positional isomers. The results showed superior separation performance of the g-C3N4 stationary phase for some critical analytes and preferential retention for aromatic analytes. Specifically, it exhibited high-resolution capability for aromatic and aliphatic isomers such as methylnaphthalenes and dimethylnaphthalenes, phenanthrene and anthracene and alkane isomers. In addition, g-C3N4 column showed excellent thermal stability up to 280°C and good repeatability with relative standard deviation (RSD) values less than 0.09% for intra-day, below 0.23% for inter-day and in the range of 1.9-8.4% for between-column, respectively. The advantageous separation performance shows the potential of g-C3N4 and related materials as stationary phase in GC and other separation technologies.

  7. Modeling and simulation of steady state model approach for horizontal three phase separator (HTPS)

    NASA Astrophysics Data System (ADS)

    Triwibowo, Bayu; Prasetiawan, Haniif; Hisyam, Anwaruddin; Fauzan, Mohammad Fariz; Rizky, Muhammad Habib Fahd

    2017-03-01

    Main function of oil production facility is to separate oil well stream into three phases i.e. oil, gas and water. A vessel called three phase separator is used for this purpose, commonly in horizontal arrangement. In order to optimize the process, an accurate model for horizontal three phase separator (HTPS) is needed. Computational Fluid Dynamics (CFD) is a mathematical tool capable of simulating a wide range of fluid flows. HTPS dimensions used in this simulation were taken from one of oil and gas company in Indonesia. The CFD simulation used in this study is based on volume of fluid and k-ɛ turbulence models. Gas outlet was assumed using porous media zone model with fluid porosity 0.99. Simulation result displayed concentration and velocity distribution for each component inside HTPS. The result of concentration distribution shows that the region of fluid divided into upper region and lower region. The lower region major component were water and upper region mainly consist of gas and oil. The contour of concentration distribution indicated a good separation process with distribution of water flow rate at the outlet of water, oil, and gas respectively are 405,67; 115,65; and 172.01 lb/min

  8. Oscillating phase separation in microemulsions. II. Description by a bending free energy

    NASA Astrophysics Data System (ADS)

    Vollmer, Jürgen; Vollmer, Doris; Strey, Reinhard

    1997-09-01

    We propose a mechanism to describe the phase separation of a single phase of water-in-oil microemulsion droplets towards a phase of smaller water droplets coexisting with a water-rich excess phase. The phase separation shows oscillatory behavior when induced by a continuous temperature increase. A periodic clouding and clearing is observed in the extinction of transmitted light which is also reflected in the specific heat. To model this behavior the bending free energy describing the equilibrium phase transition is applied to identify the energy barriers in the dynamics of this transition. They are due to conservation laws preventing the relaxation to a close to equilibrium size distribution of droplets unless volume and surface is redistributed simultaneously for a large number of droplets. By numerical integration of an expression for the time evolution of the size distribution of droplets it is verified that constant heating gives rise to oscillations. Besides clarifying the origin of the oscillations this approach also gives good estimates for heat absorbed during a single oscillation.

  9. Search for improved fluorinated stationary phases for separation of fluorine-containing pharmaceuticals from their desfluoro analogs.

    PubMed

    Regalado, Erik L; Makarov, Alexey A; McClain, Ray; Przybyciel, Matthew; Welch, Christopher J

    2015-02-06

    Evaluation of a several fluorine-containing stationary phases for the chromatographic separation of fluorine-containing pharmaceuticals from their corresponding desfluoro analogs revealed a number of perfluoroaryl and perfluoroalky stationary phases that afford good separations. These fluorous stationary phases exhibit greater retention for the fluorine-containing compounds relative to the H-containing analogs, consistent with a fluorophilic retention mechanism. While both perfluoroalkyl and perfluoroaryl stationary phases afford adequate resolution, the perfluoroaryl columns generally exhibit superior separation factor (α) and peak efficiency (N), resulting in faster baseline separations, with the Hypersil Gold PFP and Poroshell 120 PFP columns providing the best overall performance for the test group studied.

  10. Morphology Mapping of Phase-Separated Polymer Films Using Nanothermal Analysis

    SciTech Connect

    Nikiforov, Maxim; Gam, Sangah; Jesse, Stephen; Composto, Russel C; Kalinin, Sergei V

    2010-01-01

    Polymers films are attractive, in part, because their physical properties can be tuned by blending polymer with complementary characteristics. However, blending is typically challenging because most polymers will undergo phase separation, resulting in unpredictable behavior. Here, we introduce band excitation nanothermal analysis (BE-NanoTA) as a nondestructive AFM-based technique for mapping the near surface, thermal properties of polymeric coatings. BE-NanoTA was used to investigate phase separation and domain growth in poly(styrene-ran-acrylonitrile):poly(methyl methacrylate) SAN:PMMA films. The size and shape of PMMA-rich domains are consistent with prior measurements on the same system using a destructive method, namely UV-ozone etching of PMMA followed by topography mapping using standard AFM. Moreover, new insights into the mechanism of phase separation were uncovered including the observation of SAN- and PMMA-rich channels near the surface at early times as well as small SAN-rich domains trapped within large PMMA domains during intermediate times. Because it is nondestructive, BE-NanoTA can be used to explore in situ phase evolution in soft matter systems (e.g., polymer nanocomposites) which do not lend themselves to the UV-ozone etching method

  11. Surface modification of polytetrafluoroethylene column for two-stationary phase separations by counter-current chromatography.

    PubMed

    Quan, Kai-jun; Huang, Xin-yi; Li, Xiao-ting; Wang, Gao-hong; Liu, Yan-juan; Duan, Wen-da; Di, Duo-long

    2015-11-27

    To improve the separation capability of CCC, a novel solid-liquid two-stationary phases CCC (ASP-CCC) column was prepared employing graphene oxide (GO) conjugated poly-dopamine (PD) coating (GO/PD) as auxiliary stationary phase (ASP). The results of Scanning electron microscopy (SEM), contact angle and X-ray photoelectron spectroscopy (XPS) indicated that nanostructured GO and PD were successfully grafted on the inner wall of the PTFE column. Three alkaloid compounds were selected as the target analytes to evaluate the performance of the novel column. Because of the intermolecular force (hydrogen bond, electrostatic interaction and π-π interaction) between the ASP and model compounds, three analytes were well separated with this novel ASP-CCC column. Additionally, the novel column exhibited higher stationary phase retention ratio, about 8%, than original column without changing the chromatographic condition. Furthermore, the eluotropic sequence of analytes on novel column was in accordance with that in the original column. This suggested that the novel column is a CCC column with auxiliary stationary phase (ASP) in its own right, and the present separation mode is the combination of partition chromatography and adsorption chromatography.

  12. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

    SciTech Connect

    O'Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.

    2015-04-21

    Atmospheric aerosols can undergo phase transitions including liquid-liquid phase separation (LLPS) while responding to changes in the ambient relative humidity (RH). Here, we report results of chemical imaging experiments using environmental scanning electron microscopy (ESEM) and scanning transmission x-ray microscopy (STXM) to investigate the LLPS of micron sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), a, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS with apparent core-shell particle morphology were observed for all samples with both techniques. Chemical imaging with STXM showed that both LSOC/AS and HMMA/AS particles were never homogeneously mixed for all measured RH’s above the deliquescence point and that the majority of the organic component was located in the shell. The shell composition was estimated as 65:35 organic: inorganic in LSOC/AS and as 50:50 organic: inorganic for HMMA/AS. PEG-400/AS particles showed fully homogeneous mixtures at high RH and phase separated below 89-92% RH with an estimated 50:50% organic to inorganic mix in the shell. These two chemical imaging techniques are well suited for in-situ analysis of the hygroscopic behavior, phase separation, and surface composition of collected ambient aerosol particles.

  13. MPP1 as a Factor Regulating Phase Separation in Giant Plasma Membrane-Derived Vesicles

    PubMed Central

    Podkalicka, Joanna; Biernatowska, Agnieszka; Majkowski, Michał; Grzybek, Michał; Sikorski, Aleksander F.

    2015-01-01

    The existence of membrane-rafts helps to conceptually understand the spatiotemporal organization of membrane-associated events (signaling, fusion, fission, etc.). However, as rafts themselves are nanoscopic, dynamic, and transient assemblies, they cannot be directly observed in a metabolizing cell by traditional microscopy. The observation of phase separation in giant plasma membrane-derived vesicles from live cells is a powerful tool for studying lateral heterogeneity in eukaryotic cell membranes, specifically in the context of membrane rafts. Microscopic phase separation is detectable by fluorescent labeling, followed by cooling of the membranes below their miscibility phase transition temperature. It remains unclear, however, if this lipid-driven process is tuneable in any way by interactions with proteins. Here, we demonstrate that MPP1, a member of the MAGUK family, can modulate membrane properties such as the fluidity and phase separation capability of giant plasma membrane-derived vesicles. Our data suggest that physicochemical domain properties of the membrane can be modulated, without major changes in lipid composition, through proteins such as MPP1. PMID:25954878

  14. Evidence that oleic acid exists in a separate phase within stratum corneum lipids

    SciTech Connect

    Ongpipattanakul, B.; Burnette, R.R.; Potts, R.O.; Francoeur, M.L. )

    1991-03-01

    Oleic acid is known to be a penetration enhancer for polar to moderately polar molecules. A mechanism related to lipid phase separation has been previously proposed by this laboratory to explain the increases in skin transport. In the studies presented here, Fourier transform infrared spectroscopy (FT-IR) was utilized to investigate whether or not oleic acid exists in a separate phase within stratum corneum (SC) lipids. Per-deuterated oleic acid was employed allowing the conformational phase behavior of the exogenously added fatty acid and the endogenous SC lipids to be monitored independently of each other. The results indicated that oleic acid exerts a significant effect on the SC lipids, lowering the lipid transition temperature (Tm) in addition to increasing the conformational freedom or flexibility of the endogenous lipid alkyl chains above their Tm. At temperatures lower than Tm, however, oleic acid did not significantly change the chain disorder of the SC lipids. Similar results were obtained with lipids isolated from the SC by chloroform:methanol extraction. Oleic acid, itself, was almost fully disordered at temperatures both above and below the endogenous lipid Tm in the intact SC and extracted lipid samples. This finding suggested that oleic acid does exist as a liquid within the SC lipids. The coexistence of fluid oleic acid and ordered SC lipids, at physiological temperatures, is consistent with the previously proposed phase-separation transport mechanism for enhanced diffusion.

  15. Dual Phase Separation for Synthesis of Bimodal Meso/Macroporous Carbon Monoliths

    SciTech Connect

    Liang, Chengdu; Dai, Sheng

    2009-01-01

    Polymerization-induced spinodal decomposition was conducted in glycolic solutions of phloroglucinol/formaldehyde (PF) copolymer and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) to synthesize bicontinuous macroporous morphologies with micro-domains from 0.5 to 6 microns. The polymeric materials were further carbonized at elevated temperature to yield bimodal meso/macroporous carbon monoliths after the thermal decomposition of the PEO-PPO-PEO template. The bimodal porous nature of the resultant carbon monoliths resulted from the dual phase separation, in which spinodal decomposition and microphase separation occurred simultaneously. We demonstrated the tunability of macropores without alteration of mesopore sizes.

  16. Zero-g experiments with a He II active phase separator for space application

    NASA Astrophysics Data System (ADS)

    Denner, H. D.; Klipping, G.; Lueders, K.; Ruppert, U.; Stahnke, F.; Szuecs, Z.; Elleman, D.; Petrac, D.

    An active phase separator (APS) for temperature control of He II space cooling systems was tested in a zero-g environment during a series of parabolic flights on a NASA KC 135 aircraft. The APS provides for liquid-gas separation and features an annular gap, a downstream heat exchanger and an upstream ball closure. The apparatus was operated during acceleration and floating and in two different heat load situations. The tests confirmed that adequate mass flow rates could be maintained using a vacuum pump to simulate space vacuum and that residual liquid could be evaporated from the heat exchanger after closing a ball valve to seal off flows.

  17. Crystal growth in a three-phase system: Diffusion and liquid-liquid phase separation in lysozyme crystal growth

    NASA Astrophysics Data System (ADS)

    Heijna, M. C. R.; van Enckevort, W. J. P.; Vlieg, E.

    2007-07-01

    In the phase diagram of the protein hen egg-white lysozyme, a region is present in which the lysozyme solution demixes and forms two liquid phases. In situ observations by optical microscopy show that the dense liquid droplets dissolve when crystals grow in this system. During this process the demixed liquid region retracts from the crystal surface. The spatial distribution of the dense phase droplets present special boundary conditions for Fick’s second law for diffusion. In combination with the cylindrical symmetry provided by the kinetically roughened crystals, this system allows for a full numerical analysis. Using experimental data for setting the boundary conditions, a quasi-steady-state solution for the time-dependent concentration profile was shown to be valid. Comparison of kinetically rough growth in a phase separated system and in a nonseparated system shows that the growth kinetics for a three-phase system differs from a two-phase system, in that crystals grow more slowly but the duration of growth is prolonged.

  18. Crystal growth in a three-phase system: diffusion and liquid-liquid phase separation in lysozyme crystal growth.

    PubMed

    Heijna, M C R; van Enckevort, W J P; Vlieg, E

    2007-07-01

    In the phase diagram of the protein hen egg-white lysozyme, a region is present in which the lysozyme solution demixes and forms two liquid phases. In situ observations by optical microscopy show that the dense liquid droplets dissolve when crystals grow in this system. During this process the demixed liquid region retracts from the crystal surface. The spatial distribution of the dense phase droplets present special boundary conditions for Fick's second law for diffusion. In combination with the cylindrical symmetry provided by the kinetically roughened crystals, this system allows for a full numerical analysis. Using experimental data for setting the boundary conditions, a quasi-steady-state solution for the time-dependent concentration profile was shown to be valid. Comparison of kinetically rough growth in a phase separated system and in a nonseparated system shows that the growth kinetics for a three-phase system differs from a two-phase system, in that crystals grow more slowly but the duration of growth is prolonged.

  19. Investigation of phase separation behavior and formation of plasmonic nanocomposites from polypeptide-gold nanorod nanoassemblies.

    PubMed

    Huang, Huang-Chiao; Nanda, Alisha; Rege, Kaushal

    2012-04-24

    Genetically engineered elastin-like polypeptides (ELP) can be interfaced with cetyltrimethyl ammonium bromide (CTAB)-stabilized gold nanorods (GNRs) resulting in the formation of stable dispersions (nanoassemblies). Increasing the dispersion temperature beyond the ELP transition temperature results in phase separation and formation of solid-phase ELP-GNR matrices (nanocomposites). Here, we investigated different physicochemical conditions that influence nanocomposite formation from temperature-induced phase separation of ELP-GNR nanoassemblies. The presence of cetyltrimethyl ammonium bromide (CTAB), used to template the formation of gold nanorods, plays a significant role in the phase separation behavior, with high concentrations of the surfactant leading to dramatic enhancements in ELP transition temperature. Nanocomposites could be generated at 37 °C in the presence of low CTAB concentrations (<1.5 mM); higher concentrations of CTAB necessitated higher temperatures (60 °C) due to elevated transition temperatures. The concentration of gold nanorods, however, had minimal influence on the phase separation behavior and nanocomposite formation. Further analysis of the kinetics of nanocomposite formation using a mathematical model indicated that CTAB largely influenced the early event of coacervation of ELP-GNR nanoassemblies leading to nanocomposites, but had minimal effect on nanocomposite maturation, which is a later-stage longer event. Finally, nanocomposites prepared in the presence of low CTAB concentrations demonstrated a superior photothermal response following laser irradiation compared to those generated using higher CTAB concentrations. Our results on understanding the formation of plasmonic/photothermal ELP-GNR nanocomposites have significant implications for tissue engineering, regenerative medicine, and drug delivery.

  20. The effect of charge separation on the phase behavior of dipolar colloidal rods.

    PubMed

    Rutkowski, David M; Velev, Orlin D; Klapp, Sabine H L; Hall, Carol K

    2016-06-14

    Colloids with anisotropic shape and charge distribution can assemble into a variety of structures that could find use as novel materials for optical, photonic, electronic and structural applications. Because experimental characterization of the many possible types of multi-shape and multipolar colloidal particles that could form useful structures is difficult, the search for novel colloidal materials can be enhanced by simulations of colloidal particle assembly. We have simulated a system of dipolar colloidal rods at fixed aspect ratio using discontinuous molecular dynamics (DMD) to investigate how the charge separation of an embedded dipole affects the types of assemblies that occur. Each dipolar rod is modeled as several overlapping spheres fixed in an elongated shape to represent excluded volume and two smaller, embedded spheres to represent the charges that make up the extended dipole. Large charge separations predominately form structures where the rods link head-to-tail while small charge separations predominately form structures where the rods stack side-by-side. Rods with small charge separations tend to form dense aggregates while rods with large charge separations tend to form coarse gel-like structures. Structural phase boundaries between fluid, string-fluid, and "gel" (networked) phases are mapped out and characterized as to whether they have global head-to-tail or global side-by-side order. A structural coarsening transition is observed for particles with large charge separations in which the head-tail networks thicken as temperature is lowered due to an increased tendency to form side-by-side structures. Triangularly connected networks form at small charge separations; these may be useful for encapsulating smaller particles.

  1. Rapid variations in fluid chemistry constrain hydrothermal phase separation at the Main Endeavour Field

    NASA Astrophysics Data System (ADS)

    Love, Brooke; Lilley, Marvin; Butterfield, David; Olson, Eric; Larson, Benjamin

    2017-02-01

    Previous work at the Main Endeavour Field (MEF) has shown that chloride concentration in high-temperature vent fluids has not exceeded 510 mmol/kg (94% of seawater), which is consistent with brine condensation and loss at depth, followed by upward flow of a vapor phase toward the seafloor. Magmatic and seismic events have been shown to affect fluid temperature and composition and these effects help narrow the possibilities for sub-surface processes. However, chloride-temperature data alone are insufficient to determine details of phase separation in the upflow zone. Here we use variation in chloride and gas content in a set of fluid samples collected over several days from one sulfide chimney structure in the MEF to constrain processes of mixing and phase separation. The combination of gas (primarily magmatic CO2 and seawater-derived Ar) and chloride data, indicate that neither variation in the amount of brine lost, nor mixing of the vapor phase produced at depth with variable quantities of (i) brine or (ii) altered gas rich seawater that has not undergone phase separation, can explain the co-variation of gas and chloride content. The gas-chloride data require additional phase separation of the ascending vapor-like fluid. Mixing and gas partitioning calculations show that near-critical temperature and pressure conditions can produce the fluid compositions observed at Sully vent as a vapor-liquid conjugate pair or as vapor-liquid pair with some remixing, and that the gas partition coefficients implied agree with theoretically predicted values.Plain Language SummaryWhen the chemistry of fluids from deep sea hot springs changes over a short time span, it allows us to narrow down the conditions and processes that created those fluids. This gives us a better idea what is happening under the seafloor where the water is interacting with hot rocks and minerals, boiling, and taking on the character it will have when it emerges at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23554360','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23554360"><span id="translatedtitle">Selectivity differences of water-soluble vitamins <span class="hlt">separated</span> on hydrophilic interaction stationary <span class="hlt">phases</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Yuanzhong; Boysen, Reinhard I; Hearn, Milton T W</p> <p>2013-06-01</p> <p>In this study, the retention behavior and selectivity differences of water-soluble vitamins were evaluated with three types of polar stationary <span class="hlt">phases</span> (i.e. an underivatized silica <span class="hlt">phase</span>, an amide <span class="hlt">phase</span>, and an amino <span class="hlt">phase</span>) operated in the hydrophilic interaction chromatographic mode with ESI mass spectrometric detection. The effects of mobile <span class="hlt">phase</span> composition, including buffer pH and concentration, on the retention and selectivity of the vitamins were investigated. In all stationary <span class="hlt">phases</span>, the neutral or weakly charged vitamins exhibited very weak retention under each of the pH conditions, while the acidic and more basic vitamins showed diverse retention behaviors. With the underivatized silica <span class="hlt">phase</span>, increasing the salt concentration of the mobile <span class="hlt">phase</span> resulted in enhanced retention of the acidic vitamins, but decreased retention of the basic vitamins. These observations thus signify the involvement of secondary mechanisms, such as electrostatic interaction in the retention of these analytes. Under optimized conditions, a baseline <span class="hlt">separation</span> of all vitamins was achieved with excellent peak efficiency. In addition, the effects of water content in the sample on retention and peak efficiency were examined, with sample stacking effects observed when the injected sample contained a high amount of water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17595947','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17595947"><span id="translatedtitle">Superheated water as chromatographic eluent for parabens <span class="hlt">separation</span> on octadecyl coated zirconia stationary <span class="hlt">phase</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dugo, Paola; Buonasera, Katia; Crupi, Maria Lucia; Cacciola, Francesco; Dugo, Giovanni; Mondello, Luigi</p> <p>2007-05-01</p> <p>In this study, the use of pure water at superheated temperatures, between 100 and 200 degrees C, as a mobile <span class="hlt">phase</span> for RP <span class="hlt">separation</span> is explored. Instrumental parameters, such as temperature, flow rate, preheating and cooling, have shown significant effects on the quality of the chromatographic peaks. The properties of superheated water as an eluent were investigated by observing the chromatographic behaviour of four parabens on a carbon-clad zirconia (ZR) <span class="hlt">phase</span> with covalently bonded octadecyl groups. Results were compared with those obtained at 30 degrees C on a silica-based <span class="hlt">phase</span> with octadecyl groups, using water and ACN as mobile <span class="hlt">phase</span>. The optimized method was finally applied to analyse parabens in a commercial body cream.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24033058','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24033058"><span id="translatedtitle">Anisotropic electronic state via spontaneous <span class="hlt">phase</span> <span class="hlt">separation</span> in strained vanadium dioxide films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, M K; Wagner, M; Abreu, E; Kittiwatanakul, S; McLeod, A; Fei, Z; Goldflam, M; Dai, S; Fogler, M M; Lu, J; Wolf, S A; Averitt, R D; Basov, D N</p> <p>2013-08-30</p> <p>We resolved the enigma of anisotropic electronic transport in strained vanadium dioxide (VO2) films by inquiring into the role that strain plays in the nanoscale <span class="hlt">phase</span> <span class="hlt">separation</span> in the vicinity of the insulator-to-metal transition. The root source of the anisotropy was visualized as the formation of a peculiar unidirectional stripe state which accompanies the <span class="hlt">phase</span> transition. Furthermore, nanoscale infrared spectroscopy unveils distinct facets of electron-lattice interplay at three different stages of the <span class="hlt">phase</span> transition. These stages include the initial formation of sparse nonpercolating metallic domains without noticeable involvement of the lattice followed by an electron-lattice coupled anisotropic stripe state close to percolation which ultimately evolves into a nearly isotropic rutile metallic <span class="hlt">phase</span>. Our results provide a unique mesoscopic perspective for the tunable macroscopic phenomena in strained metal oxide films.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhRvL.111i6602L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhRvL.111i6602L"><span id="translatedtitle">Anisotropic Electronic State via Spontaneous <span class="hlt">Phase</span> <span class="hlt">Separation</span> in Strained Vanadium Dioxide Films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, M. K.; Wagner, M.; Abreu, E.; Kittiwatanakul, S.; McLeod, A.; Fei, Z.; Goldflam, M.; Dai, S.; Fogler, M. M.; Lu, J.; Wolf, S. A.; Averitt, R. D.; Basov, D. N.</p> <p>2013-08-01</p> <p>We resolved the enigma of anisotropic electronic transport in strained vanadium dioxide (VO2) films by inquiring into the role that strain plays in the nanoscale <span class="hlt">phase</span> <span class="hlt">separation</span> in the vicinity of the insulator-to-metal transition. The root source of the anisotropy was visualized as the formation of a peculiar unidirectional stripe state which accompanies the <span class="hlt">phase</span> transition. Furthermore, nanoscale infrared spectroscopy unveils distinct facets of electron-lattice interplay at three different stages of the <span class="hlt">phase</span> transition. These stages include the initial formation of sparse nonpercolating metallic domains without noticeable involvement of the lattice followed by an electron-lattice coupled anisotropic stripe state close to percolation which ultimately evolves into a nearly isotropic rutile metallic <span class="hlt">phase</span>. Our results provide a unique mesoscopic perspective for the tunable macroscopic phenomena in strained metal oxide films.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JPhA...37.3769L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JPhA...37.3769L"><span id="translatedtitle">New kind of <span class="hlt">phase</span> <span class="hlt">separation</span> in a CA traffic model with anticipation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lárraga, M. E.; del Río, J. A.; Schadschneider, A.</p> <p>2004-03-01</p> <p>A cellular automaton model of traffic flow taking into account velocity anticipation is introduced. The strength of anticipation can be varied to describe different driving schemes. We find a new <span class="hlt">phase</span> <span class="hlt">separation</span> into a free-flow regime and a so-called v-platoon in an intermediate density regime. In a v-platoon all cars move with velocity v and have vanishing headway. The velocity v of a platoon only depends on the strength of anticipation. At high densities, a congested state characterized by the coexistence of a 0-platoon with several v-platoons is reached. The results are not only relevant for automated highway systems, but also help to elucidate the effects of anticipation that play an essential role in realistic traffic models. From a physics point of view the model is interesting because it exhibits <span class="hlt">phase</span> <span class="hlt">separation</span> with a condensed <span class="hlt">phase</span> in which particles move coherently with finite velocity coexisting with either a non-condensed (free-flow) <span class="hlt">phase</span> or another condensed <span class="hlt">phase</span> that is non-moving.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT........13O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT........13O"><span id="translatedtitle">The rheology and <span class="hlt">phase</span> <span class="hlt">separation</span> kinetics of mixed-matrix membrane dopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olanrewaju, Kayode Olaseni</p> <p></p> <p>Mixed-matrix hollow fiber membranes are being developed to offer more efficient gas <span class="hlt">separations</span> applications than what the current technologies allow. Mixed-matrix membranes (MMMs) are membranes in which molecular sieves incorporated in a polymer matrix enhance <span class="hlt">separation</span> of gas mixtures based on the molecular size difference and/or adsorption properties of the component gases in the molecular sieve. The major challenges encountered in the efficient development of MMMs are associated with some of the paradigm shifts involved in their processing, as compared to pure polymer membranes. For instance, mixed-matrix hollow fiber membranes are prepared by a dry-wet jet spinning method. Efficient large scale processing of hollow fibers by this method requires knowledge of two key process variables: the rheology and kinetics of <span class="hlt">phase</span> <span class="hlt">separation</span> of the MMM dopes. Predicting the rheological properties of MMM dopes is not trivial; the presence of particles significantly affects neat polymer membrane dopes. Therefore, the need exists to characterize and develop predictive capabilities for the rheology of MMM dopes. Furthermore, the kinetics of <span class="hlt">phase</span> <span class="hlt">separation</span> of polymer solutions is not well understood. In the case of MMM dopes, the kinetics of <span class="hlt">phase</span> <span class="hlt">separation</span> are further complicated by the presence of porous particles in a polymer solution. Thus, studies on the <span class="hlt">phase</span> <span class="hlt">separation</span> kinetics of polymer solutions and suspensions of zeolite particles in polymer solutions are essential. Therefore, this research thesis aims to study the rheology and <span class="hlt">phase</span> <span class="hlt">separation</span> kinetics of mixed-matrix membrane dopes. In our research efforts to develop predictive models for the shear rheology of suspensions of zeolite particles in polymer solutions, it was found that MFI zeolite suspensions have relative viscosities that dramatically exceed the Krieger-Dougherty predictions for hard sphere suspensions. Our investigations showed that the major origin of this discrepancy is the selective</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhRvE..58.1211A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhRvE..58.1211A"><span id="translatedtitle">Liquid-crystal-anchoring transitions at surfaces created by polymerization-induced <span class="hlt">phase</span> <span class="hlt">separation</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amundson, Karl R.; Srinivasarao, Mohan</p> <p>1998-08-01</p> <p>A surface anchoring transition of a nematic at polymer surfaces created by polymerization-induced <span class="hlt">phase</span> <span class="hlt">separation</span> is presented. This transition is unusual in that it occurs far from bulk nematic <span class="hlt">phase</span> transitions and it is tunable across nearly the entire nematic temperature range by modification of the polymer side group. Anchoring behavior is qualitatively understood by considerating enthalpic and entropic contributions to surface energy. Interesting behavior of some polymer-dispersed liquid-crystal films is explained, and observations provide a pathway to control properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21386741','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21386741"><span id="translatedtitle"><span class="hlt">Phase</span> <span class="hlt">separation</span> and pairing regimes in the one-dimensional asymmetric Hubbard model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barbiero, L.; Casadei, M.; Dalmonte, M.; Ercolessi, E.; Ortolani, F.</p> <p>2010-06-01</p> <p>We address some open questions regarding the <span class="hlt">phase</span> diagram of the one-dimensional Hubbard model with asymmetric hopping coefficients and balanced species. In the attractive regime we present a numerical study of the passage from on-site pairing dominant correlations at small asymmetries to charge-density waves in the region with markedly different hopping coefficients. In the repulsive regime we exploit two analytical treatments in the strong- and weak-coupling regimes in order to locate the onset of <span class="hlt">phase</span> <span class="hlt">separation</span> at small and large asymmetries, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvL.118i8002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvL.118i8002S"><span id="translatedtitle">Small Activity Differences Drive <span class="hlt">Phase</span> <span class="hlt">Separation</span> in Active-Passive Polymer Mixtures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smrek, Jan; Kremer, Kurt</p> <p>2017-03-01</p> <p>Recent theoretical studies found that mixtures of active and passive colloidal particles <span class="hlt">phase</span> <span class="hlt">separate</span> but only at very high activity ratio. The high value poses serious obstacles for experimental exploration of this phenomenon. Here we show using simulations that when the active and passive particles are polymers, the critical activity ratio decreases with the polymer length. This not only facilitates the experiments but also has implications on the DNA organization in living cell nuclei. Entropy production can be used as an accurate indicator of this nonequilibrium <span class="hlt">phase</span> transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561857','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561857"><span id="translatedtitle"><span class="hlt">Separation</span> of Quadruplex Polymorphism in DNA Sequences by Reversed-<span class="hlt">Phase</span> Chromatography</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Miller, M. Clarke; Ohrenberg, Carl J.; Kuttan, Ashani; Trent, John O.</p> <p>2015-01-01</p> <p>This unit describes a method for the <span class="hlt">separation</span> of a mixture of quadruplex conformations formed from the same parent sequence via reversed-<span class="hlt">phase</span> chromatography (RPC). Polymorphism is inherent to quadruplex formation and even relatively simple quadruplex-forming sequences can fold into a cornucopia of possible conformations and topologies. Isolation of a specific conformation for study can be problematic. This is especially true for conformations of the human telomere sequence d(GGG(TTAGGG)3), High Performance Liquid Chromatography (HPLC), especially reversed-<span class="hlt">phase</span> chromatography, has been a mainstay of nucleic acids research and purification for many decades. We have successfully applied this method to the problem of <span class="hlt">separating</span> individual quadruplex species in the ensemble from the same parent sequence. PMID:26344226</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50h5007L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50h5007L"><span id="translatedtitle">Magnetically induced nonvolatile magnetoresistance and resistance memory effect in <span class="hlt">phase-separated</span> manganite thin films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Qian; Cao, Qingqi; Wang, Dunhui; Du, Youwei</p> <p>2017-03-01</p> <p>We report the observation of magnetically induced resistance memory effect in a typical electronic <span class="hlt">phase-separated</span> manganite La5/8‑x Pr x Ca3/8MnO3 (x  =  0.3) thin film. In the hysteresis region of metal-to-insulator transition, the resistance exhibits a sharp drop with the application of magnetic field and maintains the low resistance state after the removal of field, showing a nonvolatile magnetoresistance effect. The high resistance state can be recovered until the temperature is warmed. More explicit measurements at the hysteresis region exhibit the non-volatility and irreversibility of magnetoresistance, which can be ascribed to the percolative feature in the electronic <span class="hlt">phase-separated</span> manganite. The origin and potential applications of these interesting effects are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ARPC...65...59T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ARPC...65...59T"><span id="translatedtitle"><span class="hlt">Phase</span> <span class="hlt">Separation</span> in Bulk Heterojunctions of Semiconducting Polymers and Fullerenes for Photovoltaics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treat, Neil D.; Chabinyc, Michael L.</p> <p>2014-04-01</p> <p>Thin-film solar cells are an important source of renewable energy. The most efficient thin-film solar cells made with organic materials are blends of semiconducting polymers and fullerenes called the bulk heterojunction (BHJ). Efficient BHJs have a nanoscale <span class="hlt">phase-separated</span> morphology that is formed during solution casting. This article reviews recent work to understand the nature of the <span class="hlt">phase-separation</span> process resulting in the formation of the domains in polymer-fullerene BHJs. The BHJ is now viewed as a mixture of polymer-rich, fullerene-rich, and mixed polymer-fullerene domains. The formation of this structure can be understood through fundamental knowledge of polymer physics. The implications of this structure for charge transport and charge generation are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16090140','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16090140"><span id="translatedtitle">Smoothed particle hydrodynamics model for <span class="hlt">phase</span> <span class="hlt">separating</span> fluid mixtures. I. General equations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thieulot, Cedric; Janssen, L P B M; Español, Pep</p> <p>2005-07-01</p> <p>We present a thermodynamically consistent discrete fluid particle model for the simulation of a recently proposed set of hydrodynamic equations for a <span class="hlt">phase</span> <span class="hlt">separating</span> van der Waals fluid mixture [P. Español and C.A.P. Thieulot, J. Chem. Phys. 118, 9109 (2003)]. The discrete model is formulated by following a discretization procedure given by the smoothed particle hydrodynamics (SPH) method within the thermodynamically consistent general equation for the nonequilibrium reversible-irreversible coupling (GENERIC) framework. Each fluid particle carries information on the mass, momentum, energy, and the mass fraction of the different components. The discrete model allows one to simulate nonisothermal dynamic evolution of <span class="hlt">phase</span> <span class="hlt">separating</span> fluids with surface tension effects while respecting the first and second laws of thermodynamics exactly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005PhRvE..72a6713T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005PhRvE..72a6713T"><span id="translatedtitle">Smoothed particle hydrodynamics model for <span class="hlt">phase</span> <span class="hlt">separating</span> fluid mixtures. I. General equations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thieulot, Cedric; Janssen, L. P. B. M.; Español, Pep</p> <p>2005-07-01</p> <p>We present a thermodynamically consistent discrete fluid particle model for the simulation of a recently proposed set of hydrodynamic equations for a <span class="hlt">phase</span> <span class="hlt">separating</span> van der Waals fluid mixture [P. Español and C.A.P. Thieulot, J. Chem. Phys. 118, 9109 (2003)]. The discrete model is formulated by following a discretization procedure given by the smoothed particle hydrodynamics (SPH) method within the thermodynamically consistent general equation for the nonequilibrium reversible-irreversible coupling (GENERIC) framework. Each fluid particle carries information on the mass, momentum, energy, and the mass fraction of the different components. The discrete model allows one to simulate nonisothermal dynamic evolution of <span class="hlt">phase</span> <span class="hlt">separating</span> fluids with surface tension effects while respecting the first and second laws of thermodynamics exactly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5015022','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5015022"><span id="translatedtitle">Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced <span class="hlt">Phase</span> <span class="hlt">Separation</span> in nanoconfinement</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Torino, Enza; Aruta, Rosaria; Sibillano, Teresa; Giannini, Cinzia; Netti, Paolo A.</p> <p>2016-01-01</p> <p><span class="hlt">Phase</span> <span class="hlt">separation</span> of a polymer solution exhibits a peculiar behavior when induced in a nanoconfinement. The energetic constraints introduce additional interactions between the polymer segments that reduce the number of available configurations. In our work, this effect is exploited in a one-step strategy called nanoconfined-Thermally Induced <span class="hlt">Phase</span> <span class="hlt">Separation</span> (nc-TIPS) to promote the crystallization of polymer chains into nanocapsular structures of controlled size and shell thickness. This is accomplished by performing a quench step of a low-concentrated PLLA-dioxane-water solution included in emulsions of mean droplet size <500 nm acting as nanodomains. The control of nanoconfinement conditions enables not only the production of nanocapsules with a minimum mean particle diameter of 70 nm but also the tunability of shell thickness and its crystallinity degree. The specific properties of the developed nanocapsular architectures have important implications on release mechanism and loading capability of hydrophilic and lipophilic payload compounds. PMID:27604818</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhDT........31X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhDT........31X"><span id="translatedtitle"><span class="hlt">Separation</span> of basic oligopeptides by ion-pairing reversed-<span class="hlt">phase</span> chromatography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Wenchun</p> <p></p> <p>The present thesis consist of five chapters. Chapter I introduces background information on the ion-pairing reversed-<span class="hlt">phase</span> chromatography and liquid chromatography in the critical condition. Chapter II decribes our study on the isocratic <span class="hlt">separation</span> of oligolysine (dp = 2 to 8) using a fixed content of acetonitrile (ACN) (23%) and different concentrations of HFBA in the mobile <span class="hlt">phase</span> (0.6-30.6 mM) on a Waters XBridge Shield RP18® column. We found that the retention time of oligolysine increases as the dp increases, because of an increased number of HFBA bound to the peptides. Furthermore, when [HFBA] increased, the retention time increased at different rates. The greater the dp, the faster the rate. Based on a closed pairing model that presumes an equilibrium between an unpaired state and the paired state with a fixed number of HFBA molecules, an equation was derived for the retention factor of oligolysine. In Chapter III, we compare retention behaviors of oligolysine (dp = 2 to 8) and oligoarginine (dp = 2 to 8) when they are <span class="hlt">separated</span> on the Waters XBridge Shield RP18® using fixed a ACN content (23%) and difference concentrations of HFBA (0.4-30.6 mM) in the mobile <span class="hlt">phase</span>. The retention time of oligoarginine also increased at different rates as [HFBA] increased. The greater the dp, the faster the rate. The retention time of oligolysine is shorter than that of oligarginine having the dame dp. We applied Eq.1 to analyze the plot of ln k as a function of [HFBA] for each oligopeptide component to obtain the values for n, Kip,m, and βKd,ip. For oligolysine, n increases linearly as dp increase and oligoarginine exhibits an accelerated increase in n as dp rises. The plot of ln βKd,ip against dp followed a linear relationship for both peptides. In Chapter IV, we study the effect of mobile <span class="hlt">phase</span> composition on the retention of oligolysine (dp = 2 to 8) on the Waters XBridge Shield RP18 ®. The ACN content was changed from 20% to 33% and the HFBA concentration from 0.7 to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26651704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26651704"><span id="translatedtitle">Molecular dynamics study of <span class="hlt">phase</span> <span class="hlt">separation</span> in fluids with chemical reactions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Krishnan, Raishma; Puri, Sanjay</p> <p>2015-11-01</p> <p>We present results from the first d=3 molecular dynamics (MD) study of <span class="hlt">phase-separating</span> fluid mixtures (AB) with simple chemical reactions (A⇌B). We focus on the case where the rates of forward and backward reactions are equal. The chemical reactions compete with segregation, and the coarsening system settles into a steady-state mesoscale morphology. However, hydrodynamic effects destroy the lamellar morphology which characterizes the diffusive case. This has important consequences for the <span class="hlt">phase-separating</span> structure, which we study in detail. In particular, the equilibrium length scale (ℓ(eq)) in the steady state suggests a power-law dependence on the reaction rate ε:ℓ(eq)∼ε(-θ) with θ≃1.0.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JaJAP..43.1578M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JaJAP..43.1578M"><span id="translatedtitle">Polymer Wall Formation Using Liquid-Crystal/Polymer <span class="hlt">Phase</span> <span class="hlt">Separation</span> Induced on Patterned Polyimide Films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio</p> <p>2004-12-01</p> <p>We could form lattice-shaped polymer walls in a liquid crystal (LC) layer through the thermal <span class="hlt">phase</span> <span class="hlt">separation</span> of an LC/polystyrene solution between substrates with polyimide films etched by short-wavelength ultraviolet irradiation using a photomask. The LC wetting difference between the polyimide and substrate surfaces caused the coalescence of growing LC droplets on patterned polyimide films with the progress of <span class="hlt">phase</span> <span class="hlt">separation</span>. Consequently, polymer walls were formed on substrate surface areas without polyimide films. The shape of the polymer wall formed became sharp with the use of rubbed polyimide films because the nucleation of growing LC droplets concentrated on the patterned polyimide films. It is thought that the increase in the alignment order of LC molecules in the solution near the rubbed polyimide films promotes the formation of LC molecular aggregation, which becomes the growth nuclei of LC droplets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4792294','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4792294"><span id="translatedtitle">Tunable tissue scaffolds fabricated by in situ crosslink in <span class="hlt">phase</span> <span class="hlt">separation</span> system</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Xifeng; Chen, Wenjian; Gustafson, Carl T.; Miller, A. Lee; Waletzki, Brian E.; Yaszemski, Michael J.; Lu, Lichun</p> <p>2015-01-01</p> <p>Three-dimensional (3-D) scaffolds with intrinsic porous structures are desirable in various tissue regeneration applications. In this study, a unique method that combines thermally induced <span class="hlt">phase</span> <span class="hlt">separation</span> with a photocrosslinking process was developed for the fabrication of 3-D crosslinked polymer scaffolds with densely interconnected porous structures. Biodegradable poly(propylene fumarate)-co-poly(L-lactic acid) with crosslinkable fumarate bonds were used as the structural polymer material and a dioxane/water binary system was applied for the <span class="hlt">phase</span> <span class="hlt">separation</span>. By altering the polymer composition (9, 5 and 3 wt%), different types of scaffolds with distinct morphology, mechanical strength, degradation rate, cell growth and morphology, and extracellular matrix production were fabricated. These crosslinked 3-D porous scaffolds with tunable strength and biological responses show promise for potential applications in regenerative therapies, including bone and neural tissue engineering. PMID:26989479</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...632727T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...632727T"><span id="translatedtitle">Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced <span class="hlt">Phase</span> <span class="hlt">Separation</span> in nanoconfinement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Torino, Enza; Aruta, Rosaria; Sibillano, Teresa; Giannini, Cinzia; Netti, Paolo A.</p> <p>2016-09-01</p> <p><span class="hlt">Phase</span> <span class="hlt">separation</span> of a polymer solution exhibits a peculiar behavior when induced in a nanoconfinement. The energetic constraints introduce additional interactions between the polymer segments that reduce the number of available configurations. In our work, this effect is exploited in a one-step strategy called nanoconfined-Thermally Induced <span class="hlt">Phase</span> <span class="hlt">Separation</span> (nc-TIPS) to promote the crystallization of polymer chains into nanocapsular structures of controlled size and shell thickness. This is accomplished by performing a quench step of a low-concentrated PLLA-dioxane-water solution included in emulsions of mean droplet size <500 nm acting as nanodomains. The control of nanoconfinement conditions enables not only the production of nanocapsules with a minimum mean particle diameter of 70 nm but also the tunability of shell thickness and its crystallinity degree. The specific properties of the developed nanocapsular architectures have important implications on release mechanism and loading capability of hydrophilic and lipophilic payload compounds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984JPSJ...53..335Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984JPSJ...53..335Y"><span id="translatedtitle">Non-Linear Susceptibility of Spin-Glasses on <span class="hlt">Frustrated</span> Triangular Cactus Tree</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yasumura, Kaoru; Ono, Ikuo</p> <p>1984-01-01</p> <p>In order to explore the <span class="hlt">frustration</span> effects on a non-linear susceptibility χ2 of spin-glasses, ferro-antiferromagnetic mixtures, diluted antiferromagnets and Mattis model are comperatively investigated in line with a random ordered <span class="hlt">phase</span>. The jump of χ2 in the vicinity of the transition temperature is common in these models, and the magnitude of the jump is proved to depend strongly on the concentration of antiferromagnetic bond, but weakly on that of <span class="hlt">frustration</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JChPh.120.9330L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JChPh.120.9330L"><span id="translatedtitle">A Langevin dynamics study of mobile filler particles in <span class="hlt">phase-separating</span> binary systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laradji, Mohamed</p> <p>2004-05-01</p> <p>The dynamics of <span class="hlt">phase</span> <span class="hlt">separation</span> in a simple binary mixture containing mobile filler particles that are preferentially wet by one of the two components is investigated systematically via Langevin simulations in two dimensions. We found that while the filler particles reduce the growth rate of spinodal decomposition, the domain growth remains essentially identical to that of the pure binary mixture. The growth rate diminishes as either the filler particles concentration is increased or their diffusivity is decreased.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19488170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19488170"><span id="translatedtitle"><span class="hlt">Phase</span> space tomography reconstruction of the Wigner distribution for optical beams <span class="hlt">separable</span> in Cartesian coordinates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cámara, Alejandro; Alieva, Tatiana; Rodrigo, José A; Calvo, María L</p> <p>2009-06-01</p> <p>We propose a simple approach for the <span class="hlt">phase</span> space tomography reconstruction of the Wigner distribution of paraxial optical beams <span class="hlt">separable</span> in Cartesian coordinates. It is based on the measurements of the antisymmetric fractional Fourier transform power spectra, which can be taken using a flexible optical setup consisting of four cylindrical lenses. The numerical simulations and the experimental results clearly demonstrate the feasibility of the proposed scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhRvB..75g3401L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhRvB..75g3401L"><span id="translatedtitle">Fluctuations and patterns in nanoscale surface reaction systems: Influence of reactant <span class="hlt">phase</span> <span class="hlt">separation</span> during CO oxidation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Da-Jiang; Evans, J. W.</p> <p>2007-02-01</p> <p>A realistic atomistic model is used to assess spatiotemporal behavior in nanoscale CO oxidation systems at higher pressures than for traditional ultrahigh vacuum studies. The strong influence of adspecies interactions in this regime of high reactant coverages leads to <span class="hlt">phase</span> <span class="hlt">separation</span> between oxygen-rich and CO-rich reactive states. Time-series studies reveal fluctuation-induced transitions between these states, as well as transitions between reactive and inactive states. In addition, we observe flickering spatial patterns with sharp boundaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24123636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24123636"><span id="translatedtitle">In situ studies of <span class="hlt">phase</span> <span class="hlt">separation</span> and crystallization directed by Marangoni instabilities during spin-coating.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Toolan, Daniel T W; Pullan, Nikki; Harvey, Michael J; Topham, Paul D; Howse, Jonathan R</p> <p>2013-12-23</p> <p>Results of a pioneering study are presented in which for the first time, crystallization, <span class="hlt">phase</span> <span class="hlt">separation</span> and Marangoni instabilities occurring during the spin-coating of polymer blends are directly visualized, in real-space and real-time. The results provide exciting new insights into the process of self-assembly, taking place during spin-coating, paving the way for the rational design of processing conditions, to allow desired morphologies to be obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvB..95e4401K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95e4401K"><span id="translatedtitle">Identification of a Griffiths singularity in a geometrically <span class="hlt">frustrated</span> antiferromagnet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, Jitender; Panja, Soumendra Nath; Dengre, Shanu; Nair, Sunil</p> <p>2017-02-01</p> <p>We report the observation of a Griffiths <span class="hlt">phase</span> in the geometrically <span class="hlt">frustrated</span> antiferromagnet DyBaCo 4O 7 +δ . Its onset is identified using measurements of the thermoremanent magnetization, which appears to be superior to conventional in-field measurement protocols for the characterization of the Griffiths <span class="hlt">phase</span>. Within this <span class="hlt">phase</span>, the temporal relaxation of magnetization exhibits a functional form which is expected for Heisenberg systems, reflecting the nature of spin interactions in this class of materials. Interestingly, the effective Co 2 + /Co 3 + ratio tailored by varying the oxygen nonstoichiometry δ is only seen to influence the antiferromagnetic ordering temperature (T N ), leaving the Griffiths temperature (T G ) invariant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23182277','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23182277"><span id="translatedtitle">Utilization of a diol-stationary <span class="hlt">phase</span> column in ion chromatographic <span class="hlt">separation</span> of inorganic anions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Arai, Kaori; Mori, Masanobu; Kozaki, Daisuke; Nakatani, Nobutake; Itabashi, Hideyuki; Tanaka, Kazuhiko</p> <p>2012-12-28</p> <p>We describe the ion chromatographic <span class="hlt">separation</span> of inorganic anions using a diol-stationary <span class="hlt">phase</span> column (-CH(OH)CH(2)OH; diol-column) without charged functional groups. Anions were <span class="hlt">separated</span> using acidic eluent as in typical anion-exchange chromatography. The retention volumes of anions on the diol-column increased with increasing H(+) concentration in the eluent. The anion-exchange capacities of diol-columns in the acidic eluent (pH 2.8) were larger than that of zwitterionic stationary <span class="hlt">phase</span> column but smaller than that of an anion-exchange column. The <span class="hlt">separation</span> of anions using the diol-column was strongly affected by the interaction of H(+) ions with the diol-functional groups and by the types of the eluents. In particular, the selection of the eluent was very important for controlling the retention time and resolution. Good <span class="hlt">separation</span> was obtained using a diol-column (HILIC-10) with 5 mM phthalic acid as eluent. The limits of detection at a signal-to-noise ratio of 3 ranged from 1.2 to 2.7 μM with relative standard deviations (RSD, n=5) of 0.04-0.07% for the retention time and 0.4-2.0% for the peak areas. This method was successfully applied to the determination of H(2)PO(4)(-), Cl(-), and NO(3)(-) in a liquid fertilizer sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22365122','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22365122"><span id="translatedtitle">Hydrophobic polymer monoliths as novel <span class="hlt">phase</span> <span class="hlt">separators</span>: application in continuous liquid-liquid extraction systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Peroni, Daniela; Vanhoutte, Dominique; Vilaplana, Francisco; Schoenmakers, Peter; de Koning, Sjaak; Janssen, Hans-Gerd</p> <p>2012-03-30</p> <p>Hydrophobic macroporous polymer monoliths are shown to be interesting materials for the construction of "selective solvent gates". With the appropriate surface chemistry and porous properties the monoliths can be made permeable only for apolar organic solvents and not for water. Different poly(butyl methacrylate-co-ethylene dimethacrylate) (BMA-EDMA) and poly(styrene-co-divinylbenzene) (PS-DVB) monoliths prepared with tailored chemistries and porosities were evaluated for this purpose. After extensive characterization, the PS-DVB monoliths were selected due to their higher hydrophobicity and their more suitable flow characteristics. BMA-EDMA monoliths are preferred for mid-polarity solvents such as ethyl acetate, for which they provide efficient <span class="hlt">separation</span> from water. Breakthrough experiments confirmed that the pressures necessary to generate flow of organic solvents through PS-DVB monoliths were substantially lower than for water. A <span class="hlt">phase</span> <span class="hlt">separator</span> was constructed using the monoliths as the flow selector. This device was successfully coupled on-line with a chip-based continuous liquid-liquid-extraction (LLE) system with segmented flow. Efficient <span class="hlt">separation</span> of different solvents was obtained across a wide range of flow rates (0.5-4.0 mL min(-1)) and aqueous-to-organic flow ratios (β=1-10). Good robustness and long life-time were also confirmed. The suitability of the device to perform simple, cheap, and reliable <span class="hlt">phase</span> <span class="hlt">separation</span> in a continuous LLE system prior to gas-chromatographic analysis was proven for some selected real-life applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23818579','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23818579"><span id="translatedtitle"><span class="hlt">Phase</span> <span class="hlt">separation</span> explains a new class of self-organized spatial patterns in ecological systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Quan-Xing; Doelman, Arjen; Rottschäfer, Vivi; de Jager, Monique; Herman, Peter M J; Rietkerk, Max; van de Koppel, Johan</p> <p>2013-07-16</p> <p>The origin of regular spatial patterns in ecological systems has long fascinated researchers. Turing's activator-inhibitor principle is considered the central paradigm to explain such patterns. According to this principle, local activation combined with long-range inhibition of growth and survival is an essential prerequisite for pattern formation. Here, we show that the physical principle of <span class="hlt">phase</span> <span class="hlt">separation</span>, solely based on density-dependent movement by organisms, represents an alternative class of self-organized pattern formation in ecology. Using experiments with self-organizing mussel beds, we derive an empirical relation between the speed of animal movement and local animal density. By incorporating this relation in a partial differential equation, we demonstrate that this model corresponds mathematically to the well-known Cahn-Hilliard equation for <span class="hlt">phase</span> <span class="hlt">separation</span> in physics. Finally, we show that the predicted patterns match those found both in field observations and in our experiments. Our results reveal a principle for ecological self-organization, where <span class="hlt">phase</span> <span class="hlt">separation</span> rather than activation and inhibition processes drives spatial pattern formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MARF43002R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MARF43002R"><span id="translatedtitle">Controlling <span class="hlt">Phase</span> <span class="hlt">Separation</span> of Interpenetrating Polymer Networks by Addition of Block Copolymers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rohde, Brian; Krishnamoorti, Ramanan; Robertson, Megan</p> <p>2015-03-01</p> <p>Interpenetrating polymer networks (IPNs) offer a unique way to produce mechanically superior thermoset blends relative to the neat components. In this study, IPNs were prepared consisting of polydicyclopentadiene (polyDCPD), contributing high fracture toughness, and an epoxy resin (the diglycidyl ether of bisphenol A cured with nadic methyl anhydride), contributing high tensile strength and modulus. In the absence of compatibilization, the simultaneous curing of the networks leads to a macroscopically <span class="hlt">phase</span> <span class="hlt">separated</span> blend that exhibits poor mechanical behavior. To control <span class="hlt">phase</span> <span class="hlt">separation</span> and drive the system towards more mechanically robust nanostructured IPNs, block copolymers were designed to compatibilize this system, where one block possesses affinity to polyDCPD (polynorbornene in this study) and the other block possesses affinity to DGEBA (poly(ɛ-caprolactone) in this study). The influence of the block copolymer composition on the degree of <span class="hlt">phase</span> <span class="hlt">separation</span> and interfacial adhesion in the IPN was studied using a combination of small-angle scattering and imaging techniques. The resultant mechanical properties were explored and structure-property relationships were developed in this blend system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014MolPh.112.1313R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014MolPh.112.1313R"><span id="translatedtitle">Salt-induced effective interactions and <span class="hlt">phase</span> <span class="hlt">separation</span> of an ultrasoft model of polyelectrolytes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rotenberg, Benjamin; Bernard, Olivier; Hansen, Jean-Pierre</p> <p>2014-05-01</p> <p>We use a semi-grand canonical version of mean-field density functional theory to determine the total effective interaction energy of a solution of penetrable polyions characterised by a Gaussian charge distribution, in the presence of added salt. We then apply this effective representation of semi-flexible polyelectrolyte chains to investigate the possibility of a <span class="hlt">phase</span> <span class="hlt">separation</span> similar to that predicted earlier for charge-stabilised hard-sphere colloids. Apart from the absence of a hard-core repulsion, the effective pair potential is similar to the familiar Derjaguin-Landau-Verwey-Overbeek (DLVO) potential between charged-stabilised colloids, i.e. of the screened-Coulomb (Yukawa) form, but the effective valence of the polyions differs significantly from that of the DLVO pair potential, especially at high salt concentration. The existence of a well-defined closed-loop spinodal curve predicted by our mean-field calculation points to a <span class="hlt">phase</span> <span class="hlt">separation</span> between solutions with high and low polyion concentrations under reasonable physical conditions. The salt concentration at the upper critical point is typically two orders of magnitude larger than in the case of hard-core polyions, indicating that polyion penetrability appears to enhance the tendency towards <span class="hlt">phase</span> <span class="hlt">separation</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5041185','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5041185"><span id="translatedtitle">Correlation between structural heterogeneity and plastic deformation for <span class="hlt">phase</span> <span class="hlt">separating</span> FeCu metallic glasses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Peng, Chuan-Xiao; Song, Kai-Kai; Wang, Li; Şopu, Daniel; Pauly, Simon; Eckert, Jürgen</p> <p>2016-01-01</p> <p>Unlike crystalline metals, the plastic deformation of metallic glasses (MGs) involves a competition between disordering and structural relaxation ordering, which is not well understood, yet. Molecular dynamics (MD) simulations were performed to investigate the evolutions of strain localizations, short-range order (SRO) as well as the free volume in the glass during compressive deformation of Fe50Cu50 MGs with different degrees of <span class="hlt">phase</span> <span class="hlt">separation</span>. Our findings indicate that the free volume in the <span class="hlt">phase</span> <span class="hlt">separating</span> MGs decreases while the shear strain localizations increase with increasing degree of <span class="hlt">phase</span> <span class="hlt">separation</span>. Cu-centered clusters show higher potential energies and Voronoi volumes, and bear larger local shear strains. On the other hand, Fe-centered pentagon-rich clusters in Cu-rich regions seem to play an important role to resist the shear transformation. The dilatation or annihilation of Voronoi volumes is due to the competition between ordering via structural relaxation and shear stress-induced deformation. The present study could provide a better understanding of the relationship between the structural inhomogeneity and the deformation of MGs. PMID:27681052</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26478268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26478268"><span id="translatedtitle">Unique insight into <span class="hlt">phase</span> <span class="hlt">separation</span> in polymer solar cells from their electric characteristics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Jian; Zhang, Fujun; An, Qiaoshi; Sun, Qianqian; Zhang, Jian; Hu, Bin</p> <p>2015-11-28</p> <p>A series of polymer solar cells (PSCs) were fabricated with indene-C60 bisadduct (ICBA) or [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) as an electron acceptor and with PBDT-TS1 as an electron donor. The donor/acceptor (D/A) <span class="hlt">phase</span> <span class="hlt">separation</span> was adjusted with different solution processing methods, consisting of cool (room temperature, 20 °C) solution, hot (70 °C) solution and the solutions with solvent additive 1,8-diiodideoctane (DIO). The champion PCE of PSCs with ICBA or PC61BM as an electron acceptor is 4.32% or 5.97% for the active layers prepared from hot solution with DIO additive or cool solution with DIO additive, respectively. The improved PCEs should be attributed to the optimized D/A <span class="hlt">phase</span> <span class="hlt">separation</span> in the active layers by adjusting the redistribution of PC61BM or the ICBA among the PBDT-TS1 networks. The degree of <span class="hlt">phase</span> <span class="hlt">separation</span> of the active layers with different acceptors was evaluated according to the current density-voltage (J-V) curves of hole-only and electron-only devices. The distribution of PC61BM or ICBA molecules in the normal direction can be simply judged from the symmetry degree of J-V curves of electron-only devices measured under the forward and reverse bias.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21370827','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21370827"><span id="translatedtitle">Influence of film thickness on the <span class="hlt">phase</span> <span class="hlt">separation</span> mechanism in ultrathin conducting polymer blend films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meier, Robert; Ruderer, Matthias A; Diethert, Alexander; Kaune, Gunar; Körstgens, Volker; Roth, Stephan V; Müller-Buschbaum, Peter</p> <p>2011-03-31</p> <p>The film morphology of thin polymer blend films based on poly[(1-methoxy)-4-(2-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) and poly(N-vinylcarbazole) (PVK) is probed as a function of film thickness. Blend films are prepared with spin-coating of polymer solutions with different concentrations on top of solid supports. The blending ratio of both conducting polymers is kept constant. The film and surface morphology is probed with grazing incidence ultrasmall-angle X-ray scattering (GIUSAXS) and atomic force microscopy (AFM). A linear dependence between the film thickness and the averaged <span class="hlt">phase</span> <span class="hlt">separation</span> is found. In addition, X-ray reflectivity measurements show an enrichment of PVK at the substrate interface. UV/vis spectroscopy measurements indicate a linearly increasing amount of both homopolymers in the blend films for increasing film thicknesses. The generalized knowledge about the influence of the film thickness on the <span class="hlt">phase</span> <span class="hlt">separation</span> behavior in conducting polymer blend films is finally used to describe the <span class="hlt">phase</span> <span class="hlt">separation</span> formation during the spin-coating process, and the results are discussed in the framework of an adapted Flory-Huggins theory for rodlike polymers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARY38006R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARY38006R"><span id="translatedtitle">Controlling <span class="hlt">Phase</span> <span class="hlt">Separation</span> of Tough Interpenetrating Polymer Networks via Addition of Amphiphilic Block Copolymers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rohde, Brian; Krishnamoorti, Ramanan; Robertson, Megan</p> <p></p> <p>Interpenetrating polymer networks (IPNs) offer a unique way to combine the mechanical properties of two thermoset systems. Often used to create a material that possesses both high toughness and tensile properties, here we use polydicyclopentadiene, cured via ring opening metathesis polymerization, to contribute high toughness and diglycidyl ether of bisphenol A cured via anhydride chemistry to contribute high tensile strength and modulus. As the uncompatibilized system reacts in the presence of one another, mesoscopic <span class="hlt">phase</span> <span class="hlt">separation</span> occurs and dictates the overall efficacy of combining mechanical properties. To control <span class="hlt">phase</span> <span class="hlt">separation</span> and drive the system towards more mechanically robust nanostructed IPNs, amphiphilic block copolymers of polybutadiene- b-polyethylene oxide, where one block possesses strong affinity to polyDCPD and the other the DGEBA, were added to the system. Here we present a systematic study of the influence of block copolymer composition in the overall blend on degree of <span class="hlt">phase</span> <span class="hlt">separation</span> and morphology using a combination of small-angle x-ray scattering (SAXS) and scanning electron microscopy (SEM) techniques. The resultant mechanical properties are then explored in an effort to link mechanical properties to blend morphology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24666206','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24666206"><span id="translatedtitle">From molecular dehydration to excess volumes of <span class="hlt">phase-separating</span> PNIPAM solutions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Philipp, Martine; Kyriakos, Konstantinos; Silvi, Luca; Lohstroh, Wiebke; Petry, Winfried; Krüger, Jan K; Papadakis, Christine M; Müller-Buschbaum, Peter</p> <p>2014-04-17</p> <p>For aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions, a structural instability leads to the collapse and aggregation of the macromolecules at the temperature-induced demixing transition. The accompanying cooperative dehydration of the PNIPAM chains is known to play a crucial role in this <span class="hlt">phase</span> <span class="hlt">separation</span>. We elucidate the impact of partial dehydration of PNIPAM on the volume changes related to the <span class="hlt">phase</span> <span class="hlt">separation</span> of dilute to concentrated PNIPAM solutions. Quasi-elastic neutron scattering enables us to directly follow the isotropic jump diffusion behavior of the hydration water and the almost freely diffusing water. As the hydration number decreases from 8 to 2 for the demixing 25 mass % PNIPAM solution, only a partial dehydration of the PNIPAM chains occurs. Dilatation studies reveal that the transition-induced volume changes depend in a remarkable manner on the PNIPAM concentration of the solutions. The excess volume per mole of H2O molecules expelled from the solvation layers of PNIPAM during <span class="hlt">phase</span> <span class="hlt">separation</span> probably strongly increases from dilute to concentrated PNIPAM solutions. This finding is qualitatively related to the immense strain-softening previously observed for demixing PNIPAM solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26572324','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26572324"><span id="translatedtitle">Lamellar, micro-<span class="hlt">phase</span> <span class="hlt">separated</span> blends of methyl cellulose and dendritic polyethylene glycol, POSS-PEG.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chinnam, Parameswara Rao; Mantravadi, Ramya; Jimenez, Jayvic C; Dikin, Dmitriy A; Wunder, Stephanie L</p> <p>2016-01-20</p> <p>Blends of methyl cellulose (MC) and liquid pegylated polyoctahedralsilsesquioxane (POSS-PEG) were prepared from non-gelled, aqueous solutions at room temperature (RT), which was below their gel temperatures (Tm). Lamellar, fibrillated films (pure MC) and increasingly micro-porous morphologies with increasing POSS-PEG content were formed, which had RT moduli between 1 and 5GPa. Evidence of distinct micro-<span class="hlt">phase</span> <span class="hlt">separated</span> MC and POSS-PEG domains was indicated by the persistence of the MC and POSS-PEG (at 77K) crystal structures in the X-ray diffraction data, and scanning transmission electron images. Mixing of MC and POSS-PEG in the interface region was indicated by suppression of crystallinity in the POSS-PEG, and increases/decreases in the glass transition temperatures (Tg) of POSS-PEG/MC in the blends compared with the pure components. These interface interactions may serve as cross-link sites between the micro-<span class="hlt">phase</span> <span class="hlt">separated</span> domains that permit incorporation of high amounts of POSS-PEG in the blends, prevent macro-<span class="hlt">phase</span> <span class="hlt">separation</span> and result in rubbery material properties (at high POSS-PEG content). Above Tg/Tm of POSS-PEG, the moduli of the blends increase with MC content as expected. However, below Tg/Tm of POSS-PEG, the moduli are greater for blends with high POSS-PEG content, suggesting that it behaves like semi-crystalline polyethylene oxide reinforced with silica (SiO1.5).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MART28012S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MART28012S"><span id="translatedtitle">Laser <span class="hlt">Phase</span> <span class="hlt">Separation</span> of Si Rich Oxides: The Role of Composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sungur Ozen, Emel; Aydinli, Atilla; Gundogdu, Sinan</p> <p>2012-02-01</p> <p>Continuous-wave laser annealing of Si-rich oxide thin films with varying Si content were performed in order to obtain Si nanocrystals (Sinc) embedded in silica. The composition, irradiation times and power densities were investigated as well as the role of hydrogen in <span class="hlt">phase</span> <span class="hlt">separation</span>. Sinc in SiO2 appear to be very promising for the realization of optical function as light emission or optical memory. Nanocrystaline Si finds also important utility in photovoltaics thanks to quantum confinement in the nanostructures offering a wider bandgap material which, in a tandem configuration, can allow a better use of the solar spectrum. Conventional techniques utilize high-temperature processing to obtain Si-SiO2 <span class="hlt">phase</span> <span class="hlt">separation</span>. These processes are not compatible with mass production methods. An alternative approach capable of avoiding high temperature processing is the laser annealing of SiOx films. The structural effect due to annealing were investigated by Raman and photoluminescence spectroscopy. It has been shown that the size and amount of Sinc depends both on the oxygen content and on the laser power density. PECVD grown hydrogenated SiOx films were compared with sputtered films without hydrogen to identify its role for the <span class="hlt">phase</span> <span class="hlt">separation</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25541813','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25541813"><span id="translatedtitle">Glass-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> in highly supersaturated aqueous solutions of telaprevir.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mosquera-Giraldo, Laura I; Taylor, Lynne S</p> <p>2015-02-02</p> <p>Amorphous solid dispersions are of great current interest because they can improve the delivery of poorly water-soluble compounds. It has been recently noted that the highly supersaturated solutions generated by dissolution of some ASDs can undergo a <span class="hlt">phase</span> transition to a colloidal, disordered, drug-rich <span class="hlt">phase</span> when the concentration exceeds the "amorphous solubility" of the drug. The purpose of this study was to investigate the <span class="hlt">phase</span> behavior of supersaturated solutions of telaprevir, which is formulated as an amorphous solid dispersion in the commercial product. Different analytical techniques including proton nuclear magnetic resonance spectroscopy (NMR), ultraviolet spectroscopy (UV), fluorescence spectroscopy and flux measurements were used to evaluate the properties of aqueous supersaturated solutions of telaprevir. It was found that highly supersaturated solutions of telaprevir underwent glass-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> (GLPS) when the concentration exceeded 90 μg/mL, forming a water-saturated colloidal, amorphous drug-rich <span class="hlt">phase</span> with a glass transition temperature of 52 °C. From flux measurements, it was observed that the "free" drug concentration reached a maximum at the concentration where GLPS occurred, and did not increase further as the concentration was increased. This <span class="hlt">phase</span> behavior, which results in a precipitate and a metastable equilibrium between a supersaturated solution and a drug-rich <span class="hlt">phase</span>, is obviously important in the context of evaluating amorphous solid dispersion formulations and their crystallization routes.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17361308','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17361308"><span id="translatedtitle">X-ray <span class="hlt">phase</span>-contrast imaging: transmission functions <span class="hlt">separable</span> in Cartesian coordinates.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cao, Guohua; Hamilton, Theron J; Rose-Petruck, Christoph; Diebold, Gerald J</p> <p>2007-04-01</p> <p>In-line, x-ray <span class="hlt">phase</span>-contrast imaging is responsive to both <span class="hlt">phase</span> changes and absorption as the x radiation traverses a body. Expressions are derived for <span class="hlt">phase</span>-contrast imaging of objects having transmission functions <span class="hlt">separable</span> in Cartesian coordinates. Starting from the Fresnel-Kirchhoff integral formula for image formation, an expression is found for the <span class="hlt">phase</span>-contrast image produced by an x-ray source with nonvanishing dimensions. This expression is evaluated in limiting cases where the source-to-object distance is large, where the source acts as a point source, and where the weak <span class="hlt">phase</span> approximation is valid. The integral expression for the image is evaluated for objects with simple geometrical shapes, showing the influence of the source dimensions on the visibility of <span class="hlt">phase</span>-contrast features. The expressions derived here are evaluated for cases where the magnification is substantially greater than one as would be employed in biological imaging. Experiments are reported using the in-line <span class="hlt">phase</span>-contrast imaging method with a microfocus x-ray source and a CCD camera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/2211900','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/2211900"><span id="translatedtitle"><span class="hlt">Separation</span> and indirect detection of small-chain peptides using chromophoric mobile <span class="hlt">phase</span> additives.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yuan, D X; Pietrzyk, D J</p> <p>1990-06-22</p> <p>Ruthenium(II) 1,10-phenanthroline, Ru(phen)3(2+), and ruthenium(II) 2,2'-bipyridyl, Ru(bipy)3(2+), salts were evaluated as mobile <span class="hlt">phase</span> additives for the liquid chromatographic <span class="hlt">separation</span> of small-chain peptides on a polystyrene-divinylbenzene copolymeric (Hamilton PRP-1) stationary <span class="hlt">phase</span>. In a basic mobile <span class="hlt">phase</span> peptides are anions, and retention, resolution and detection occur because of the interactions between the stationary <span class="hlt">phase</span>, the RuII complex and the peptide anion. Since the RuII complex concentration changes in the analyte band relative to the background eluent RuII complex concentration, the peptide can be detected by indirect photometric detection using the wavelength where the RuII complex absorbs. Peptide analyte peaks may be positive or negative depending on the counter-anion and its concentration. Small-chain peptides that do not contain chromophoric side-chains are detected without derivatization at about 0.1 nmol injected at a 3:1 signal-to-noise ratio. Factors that affect retention, resolution and indirect photometric detection are the RuII complex, its mobile <span class="hlt">phase</span> concentration, mobile <span class="hlt">phase</span> pH and solvent composition, and the type and concentration of the mobile <span class="hlt">phase</span> counter-anion and/or buffer anion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010004305','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010004305"><span id="translatedtitle"><span class="hlt">Phase</span> <span class="hlt">Separation</span> Kinetics in Isopycnic Mixtures of H2O/CO2/Ethoxylated Alcohol Surfactants</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lesemann, Markus; Paulaitis, Michael E.; Kaler, Eric W.</p> <p>1999-01-01</p> <p>Ternary mixtures of H2O and CO2 with ethoxylated alcohol (C(sub i)E(sub j)) surfactants form three coexisting liquid <span class="hlt">phases</span> at conditions where two of the <span class="hlt">phases</span> have equal densities (isopycnic <span class="hlt">phases</span>). Isopycnic <span class="hlt">phase</span> behavior has been observed for mixtures containing C8E5, C10E6, and C12E6 surfactants, but not for those mixtures containing either C4E1 or C8E3 surfactants. Pressure-temperature (PT) projections for this three-<span class="hlt">phase</span> equilibrium were determined for H2O/CO2/C8E5 and H2O/CO2/C10E6 mixtures at temperatures from approximately 25 to 33 C and pressures between 90 and 350 bar. Measurements of the microstructure in H2O/CO2/C12E6 mixtures as a function of temperature (25-31 C), pressure (63.1-90.7 bar), and CO2 composition (0-3.9 wt%) have also been carried out to show that while micellar structure remains essentially un-changed, critical concentration fluctuations increase as the <span class="hlt">phase</span> boundary and plait point are approached. In this report, we present our first measurements of the kinetics of isopycnic <span class="hlt">phase</span> <span class="hlt">separation</span> for ternary mixtures of H2O/CO2/C8E5.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1335132-dynamics-crowding-induced-mixing-phase-separated-lipid-bilayers','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1335132-dynamics-crowding-induced-mixing-phase-separated-lipid-bilayers"><span id="translatedtitle">Dynamics of crowding-induced mixing in <span class="hlt">phase</span> <span class="hlt">separated</span> lipid bilayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zeno, Wade F.; Johnson, Kaitlin E.; Sasaki, Darryl Y.; ...</p> <p>2016-10-10</p> <p>We use fluorescence microscopy to examine the dynamics of the crowding-induced mixing transition of liquid ordered (Lo)–liquid disordered (Ld) <span class="hlt">phase</span> <span class="hlt">separated</span> lipid bilayers when the following particles of increasing size bind to either the Lo or Ld <span class="hlt">phase</span>: Ubiquitin, green fluorescent protein (GFP), and nanolipoprotein particles (NLPs) of two diameters. These proteinaceous particles contained histidine-tags, which were <span class="hlt">phase</span> targeted by binding to iminodiacetic acid (IDA) head groups, via a Cu2+ chelating mechanism, of lipids that specifically partition into either the Lo <span class="hlt">phase</span> or Ld <span class="hlt">phase</span>. The degree of steric pressure was controlled by varying the size of the bound particlemore » (10–240 kDa) and the amount of binding sites present (i.e., DPIDA concentrations of 9 and 12 mol%) in the supported lipid multibilayer platform used here. We develop a mass transfer-based diffusional model to analyze the observed Lo <span class="hlt">phase</span> domain dissolution that, along with visual observations and activation energy calculations, provides insight into the sequence of events in crowding-induced mixing. Furthermore, our results suggest that the degree of steric pressure and target <span class="hlt">phase</span> influence not only the efficacy of steric-pressure induced mixing, but the rate and controlling mechanism for which it occurs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1335132','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1335132"><span id="translatedtitle">Dynamics of crowding-induced mixing in <span class="hlt">phase</span> <span class="hlt">separated</span> lipid bilayers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zeno, Wade F.; Johnson, Kaitlin E.; Sasaki, Darryl Y.; Risbud, Subhash H.; Longo, Marjorie L.</p> <p>2016-10-10</p> <p>We use fluorescence microscopy to examine the dynamics of the crowding-induced mixing transition of liquid ordered (L<sub>o</sub>)–liquid disordered (L<sub>d</sub>) <span class="hlt">phase</span> <span class="hlt">separated</span> lipid bilayers when the following particles of increasing size bind to either the L<sub>o</sub> or L<sub>d</sub> <span class="hlt">phase</span>: Ubiquitin, green fluorescent protein (GFP), and nanolipoprotein particles (NLPs) of two diameters. These proteinaceous particles contained histidine-tags, which were <span class="hlt">phase</span> targeted by binding to iminodiacetic acid (IDA) head groups, via a Cu<sup>2+</sup> chelating mechanism, of lipids that specifically partition into either the Lo <span class="hlt">phase</span> or Ld <span class="hlt">phase</span>. The degree of steric pressure was controlled by varying the size of the bound particle (10–240 kDa) and the amount of binding sites present (i.e., DPIDA concentrations of 9 and 12 mol%) in the supported lipid multibilayer platform used here. We develop a mass transfer-based diffusional model to analyze the observed L<sub>o</sub> <span class="hlt">phase</span> domain dissolution that, along with visual observations and activation energy calculations, provides insight into the sequence of events in crowding-induced mixing. Furthermore, our results suggest that the degree of steric pressure and target <span class="hlt">phase</span> influence not only the efficacy of steric-pressure induced mixing, but the rate and controlling mechanism for which it occurs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24919675','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24919675"><span id="translatedtitle">Tube radial distribution phenomenon with a two-<span class="hlt">phase</span> <span class="hlt">separation</span> solution of a fluorocarbon and hydrocarbon organic solvent mixture in a capillary tube and metal compounds <span class="hlt">separation</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kitaguchi, Koichi; Hanamura, Naoya; Murata, Masaharu; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko</p> <p>2014-01-01</p> <p>A fluorocarbon and hydrocarbon organic solvent mixture is known as a temperature-induced <span class="hlt">phase-separation</span> solution. When a mixed solution of tetradecafluorohexane as a fluorocarbon organic solvent and hexane as a hydrocarbon organic solvent (e.g., 71:29 volume ratio) was delivered in a capillary tube that was controlled at 10°C, the tube radial distribution phenomenon (TRDP) of the solvents was clearly observed through fluorescence images of the dye, perylene, dissolved in the mixed solution. The homogeneous mixed solution (single <span class="hlt">phase</span>) changed to a heterogeneous solution (two <span class="hlt">phases</span>) with inner tetradecafluorohexane and outer hexane <span class="hlt">phases</span> in the tube under laminar flow conditions, generating the dynamic liquid-liquid interface. We also tried to apply TRDP to a <span class="hlt">separation</span> technique for metal compounds. A model analyte mixture, copper(II) and hematin, was <span class="hlt">separated</span> through the capillary tube, and detected with a chemiluminescence detector in this order within 4 min.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22729039','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22729039"><span id="translatedtitle">Evaluation of a hydrophilic ionic liquid as a salting-out <span class="hlt">phase</span> <span class="hlt">separation</span> agent to a water-tetrahydrofuran homogeneous system for aqueous biphasic extraction <span class="hlt">separation</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hirayama, Naoki; Higo, Takaaki; Imura, Hisanori</p> <p>2012-01-01</p> <p>The use of a hydrophilic ionic liquid (IL), 1-butyl-3-methylimidazolium chloride (C(4)mimCl), as a salting-out <span class="hlt">phase</span> <span class="hlt">separation</span> agent to a water-tetrahydrofuran homogeneous system was studied for possible applications to novel aqueous biphasic extraction <span class="hlt">separation</span>. The IL showed a salting-out <span class="hlt">phase-separation</span> ability. Also, differences in the polarity between the formed two <span class="hlt">phases</span> were smaller than that when using NaCl as a salting-out agent. This result suggested that C(4)mimCl remaining in water-rich <span class="hlt">phase</span> acts not only as a salting-out agent, but also a component of a mixed-solvent. Possible uses of C(4)mimCl/NaCl mixed salting-out agent system were also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22309044','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22309044"><span id="translatedtitle"><span class="hlt">Phase</span> <span class="hlt">separation</span> and antisite defects in the thermoelectric TiNiSn half-Heusler alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kirievsky, K.; Gelbstein, Y. Fuks, D.</p> <p>2013-07-15</p> <p>The half-Heusler TiNiSn alloys have recently gained an attention as promising candidates for thermoelectric applications. Improvement of these alloys for such applications can be obtained by both electronic and compositional optimizations. The latter can result in a miscibility gap, allowing a <span class="hlt">phase</span> <span class="hlt">separation</span> in the nano-scale and consequently a thermal conductivity reduction. Combination of ab initio calculations and statistical thermodynamics was applied for studying the relative stability of a number of superstructures in TiNiSn based alloys. The quasi-binary <span class="hlt">phase</span> diagram beyond T=0 K for TiNiSn–TiNi{sub 2}Sn solid solutions was calculated using energy parameters extracted from the total energy calculations for ordered structures in the Ni sublattice. We demonstrated that a decomposition of the off-stoichiometric Ni-rich half-Heusler alloy into the stoichiometric TiNiSn <span class="hlt">phase</span> and into Ni deficient Heusler TiNi{sub 2}Sn <span class="hlt">phase</span> occurs at elevated temperatures—an effect which recently had been observed experimentally. Furthermore, favorable energetic conditions for antisite defects formation were deduced, based on calculations of the energy of formation, an effect which was explained as a cooperative process of partial disordering on the Ni sublattice. The influence of these two effects on improvement of the thermoelectric performance of TiNiSn based half Heusler compounds is discussed. - Graphical abstract: <span class="hlt">Phase</span> <span class="hlt">separation</span> and antisite defects in the thermoelectric TiNiSn alloy, are covered as methods for nanostructuring and thereby enhancement of the thermoelectric potential. - Highlights: • Ab initio calculations/statistical thermodynamics was applied for studying the TiNiSn system. • The <span class="hlt">phase</span> diagram for TiNiSn–TiNi{sub 2}Sn solid solutions was calculated. • Decomposition of the Ni-rich HH into TiNiSn and Ni deficient TiNi{sub 2}Sn <span class="hlt">phases</span> was observed. • Favorable energetic conditions for antisite defects formation were deduced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......113G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......113G"><span id="translatedtitle">Effect of electric field and strain on the magnetic properties of <span class="hlt">phase</span> <span class="hlt">separated</span> manganites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grant, Daniel M.</p> <p></p> <p>Perovskite manganese oxide (manganites) have attracted research attention due to a wide variety of complex behaviors observed, including colossal responses to external perturbations. More recent work has focused on the competing ground states and the coexistence of magnetic and non-magnetic <span class="hlt">phases</span> in manganites. Anisotropic resistance changes have been observed in high quality thin film manganites, possibly due to dielectrophoresis, upon application of an electric field. Dielectrophoresis is usually observed in fluid-like systems in an electric field but is surprisingly useful in explaining the transport properties of manganites due to the fluid-like behavior of competing <span class="hlt">phases</span>. A main goal of this dissertation is to explore the role of magnetic interactions on the dielectrophoresis effects on ferromagnetic metallic regions in <span class="hlt">phase</span> <span class="hlt">separated</span> manganite thin films. The combined effect of electric and magnetic fields in these manganites could reveal a novel form of magnetoelectric effect. In one set of experiments, a magnetic field decreased the amount of time needed for the dielectrophoresis to lead to a large drop in the resistance along one direction, showing the importance of magnetic interactions in dielectrophoresis. In another set of experiments, breaking down the large resistance of a manganite sample produced a small change in coercive field, further confirming the relationship between electric and magnetic effects in manganites. However, the largest effect on the magnetic properties of the thin films was from confinement of the competing <span class="hlt">phases</span> in micrometer scale structures fabricated on the thin films. Coercive field increases of about 100- 400% were observed in a certain range of film thicknesses. To analyze such behavior in manganites, high quality thin films of the <span class="hlt">phase-separated</span> manganite (La1-xPrx)1-yCa yMnO3 (LPCMO) were grown on NdGaO3 (NGO) substrates using pulsed laser deposition. Mangetotransport, magnetization, and scanning probe microscopy</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6356523','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6356523"><span id="translatedtitle"><span class="hlt">Separation</span> of mycotoxins, polycyclic aromatic hydrocarbons, quinones, and heterocyclic compounds on cyclodextrin bonded <span class="hlt">phases</span>: an alternative LC packing</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Armstrong, D.W.; Alak, A.; De Mond, W.; Hinze, W.L.; Riehl, T.E.</p> <p>1985-01-01</p> <p>..beta..-Cyclodextrin and gamma-cyclodextrin chiral bonded <span class="hlt">phases</span> were previously shown to be useful in the <span class="hlt">separation</span> of enantiomers, diastereomers and structural isomers. In this work it is demonstrated that these stationary <span class="hlt">phases</span> are also useful in more routine <span class="hlt">separations</span>. As such, they provide an alternative to the popular reverse <span class="hlt">phase</span> packings. Because the selectivity of cyclodextrin packings is often unique they can be used to compliment conventional columns, particularly when <span class="hlt">separating</span> complex mixtures where peak overlap is a problem. The <span class="hlt">separation</span> of several important classes of compounds is used to demonstrate the general utility of this packing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26636608','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26636608"><span id="translatedtitle">On-Chip Pressure Generation for Driving Liquid <span class="hlt">Phase</span> <span class="hlt">Separations</span> in Nanochannels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xia, Ling; Choi, Chiwoong; Kothekar, Shrinivas C; Dutta, Debashis</p> <p>2016-01-05</p> <p>In this Article, we describe the generation of pressure gradients on-chip for driving liquid <span class="hlt">phase</span> <span class="hlt">separations</span> in submicrometer deep channels. The reported pressure-generation capability was realized by applying an electrical voltage across the interface of two glass channel segments with different depths. A mismatch in the electroosmotic flow rate at this junction led to the generation of pressure-driven flow in our device, a fraction of which was then directed to an analysis channel to carry out the desired <span class="hlt">separation</span>. Experiments showed the reported strategy to be particularly conducive for miniaturization of pressure-driven <span class="hlt">separations</span> yielding flow velocities in the <span class="hlt">separation</span> channel that were nearly unaffected upon scaling down the depth of the entire fluidic network. Moreover, the small dead volume in our system allowed for high dynamic control over this pressure gradient, which otherwise was challenging to accomplish during the sample injection process using external pumps. Pressure-driven velocities up to 3.1 mm/s were realized in <span class="hlt">separation</span> ducts as shallow as 300 nm using our current design for a maximum applied voltage of 3 kV. The functionality of this integrated device was demonstrated by implementing a pressure-driven ion chromatographic analysis that relied on analyte interaction with the nanochannel surface charges to yield a nonuniform solute concentration across the channel depth. Upon coupling such analyte distribution to the parabolic pressure-driven flow profile in the <span class="hlt">separation</span> duct, a mixture of amino acids could be resolved. The reported assay yielded a higher <span class="hlt">separation</span> resolution compared to its electrically driven counterpart in which sample migration was realized using electroosmosis/electrophoresis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JChPh.124e4503H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JChPh.124e4503H"><span id="translatedtitle">Pair-correlation functions and <span class="hlt">phase</span> <span class="hlt">separation</span> in a two-component point Yukawa fluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hopkins, P.; Archer, A. J.; Evans, R.</p> <p>2006-02-01</p> <p>We investigate the structure of a binary mixture of particles interacting via purely repulsive point Yukawa pair potentials with a common inverse screening length λ. Using the hypernetted chain closure to the Ornstein-Zernike equations, we find that for a system with "ideal" (Berthelot mixing rule) pair-potential parameters for the interaction between unlike species, the asymptotic decay of the total correlation functions crosses over from monotonic to damped oscillatory on increasing the fluid total density at fixed composition. This gives rise to a Kirkwood line in the <span class="hlt">phase</span> diagram. We also consider a "nonideal" system, in which the Berthelot mixing rule is multiplied by a factor (1+δ). For any δ >0 the system exhibits fluid-fluid <span class="hlt">phase</span> <span class="hlt">separation</span> and remarkably the ultimate decay of the correlation functions is now monotonic for all (mixture) state points. Only in the limit of vanishing concentration of either species does one find oscillatory decay extending to r =∞. In the nonideal case the simple random-<span class="hlt">phase</span> approximation provides a good description of the <span class="hlt">phase</span> <span class="hlt">separation</span> and the accompanying Lifshitz line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OptLT..89...75T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OptLT..89...75T"><span id="translatedtitle">Carrier-<span class="hlt">separating</span> demodulation of <span class="hlt">phase</span> shifting self-mixing interferometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tao, Yufeng; Wang, Ming; Xia, Wei</p> <p>2017-03-01</p> <p>A carrier <span class="hlt">separating</span> method associated with noise-elimination had been introduced into a sinusoidal <span class="hlt">phase</span>-shifting self-mixing interferometer. The conventional sinusoidal <span class="hlt">phase</span> shifting self-mixing interferometry was developed into a more competitive instrument with high computing efficiency and nanometer accuracy of λ / 100 in dynamical vibration measurement. The high slew rate electro-optic modulator induced a sinusoidal <span class="hlt">phase</span> carrier with ultralow insertion loss in this paper. In order to extract <span class="hlt">phase</span>-shift quickly and precisely, this paper employed the carrier-<span class="hlt">separating</span> to directly generate quadrature signals without complicated frequency domain transforms. Moreover, most noises were evaluated and suppressed by a noise-elimination technology synthesizing empirical mode decomposition with wavelet transform. The overall laser system was described and inherent advantages such as high computational efficiency and decreased nonlinear errors of the established system were demonstrated. The experiment implemented on a high precision PZT (positioning accuracy was better than 1 nm) and compared with laser Doppler velocity meter. The good agreement of two instruments shown that the short-term resolution had improved from 10 nm to 1.5 nm in dynamic vibration measurement with reduced time expense. This was useful in precision measurement to improve the SMI with same sampling rate. The proposed signal processing was performed in pure time-domain requiring no preprocessing electronic circuits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28231012','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28231012"><span id="translatedtitle">Quantum Percolation and Magnetic Nanodroplet States in Electronically <span class="hlt">Phase-Separated</span> Manganite Nanowires.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Kaixuan; Li, Lin; Li, Hui; Feng, Qiyuan; Zhang, Nan; Cheng, Long; Fan, Xiaodong; Hou, Yubin; Lu, Qingyou; Zhang, Zhenyu; Zeng, Changgan</p> <p>2017-03-08</p> <p>One-dimensional (1D) confinement has been revealed to effectively tune the properties of materials in homogeneous states. The 1D physics can be further enriched by electronic inhomogeneity, which unfortunately remains largely unknown. Here we demonstrate the ultrahigh sensitivity to magnetic fluctuations and the tunability of <span class="hlt">phase</span> stability in the electronic transport properties of self-assembled electronically <span class="hlt">phase-separated</span> manganite nanowires with extreme aspect ratio. The onset of magnetic nanodroplet state, a precursor to the ferromagnetic metallic state, is unambiguously revealed, which is attributed to the small lateral size of the nanowires that is comparable to the droplet size. Moreover, the quasi-1D anisotropy stabilizes thin insulating domains to form intrinsic tunneling junctions in the low temperature range, which is robust even under magnetic field up to 14 T and thus essentially modifies the classic 1D percolation picture to stabilize a novel quantum percolation state. A new <span class="hlt">phase</span> diagram is therefore established for the manganite system under quasi-1D confinement for the first time. Our findings offer new insight into understanding and manipulating the colorful properties of the electronically <span class="hlt">phase-separated</span> systems via dimensionality engineering.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561900','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4561900"><span id="translatedtitle">Pressure-induced electronic <span class="hlt">phase</span> <span class="hlt">separation</span> of magnetism and superconductivity in CrAs</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; Luetkens, Hubertus; Amato, Alex; Biswas, Pabitra K.; Rüegg, Christian; Susner, Michael A.; Sefat, Athena S.; Zhigadlo, Nikolai D.; Morenzoni, Elvezio</p> <p>2015-01-01</p> <p>The recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p  3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p  7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc  1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5  p  7 kbar) the superconducting and the magnetic volume fractions are spatially <span class="hlt">phase</span> <span class="hlt">separated</span> and compete for <span class="hlt">phase</span> volume. Our results indicate that the less conductive magnetic <span class="hlt">phase</span> provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with as well as the <span class="hlt">phase</span> <span class="hlt">separation</span> between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs. PMID:26346548</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26346548','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26346548"><span id="translatedtitle">Pressure-induced electronic <span class="hlt">phase</span> <span class="hlt">separation</span> of magnetism and superconductivity in CrAs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; Luetkens, Hubertus; Amato, Alex; Biswas, Pabitra K; Rüegg, Christian; Susner, Michael A; Sefat, Athena S; Zhigadlo, Nikolai D; Morenzoni, Elvezio</p> <p>2015-09-08</p> <p>The recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5 < or ~  p < or ~ 7 kbar) the superconducting and the magnetic volume fractions are spatially <span class="hlt">phase</span> <span class="hlt">separated</span> and compete for <span class="hlt">phase</span> volume. Our results indicate that the less conductive magnetic <span class="hlt">phase</span> provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc(3.2) as well as the <span class="hlt">phase</span> <span class="hlt">separation</span> between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1259706','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1259706"><span id="translatedtitle">Pressure-induced electronic <span class="hlt">phase</span> <span class="hlt">separation</span> of magnetism and superconductivity in CrAs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; Luetkens, Hubertus; Amato, Alex; Biswas, Pabitra K.; Ruegg, Christian; Susner, Michael A.; Sefat, Athena S.; Zhigadlo, Nikolai D.; Morenzoni, Elvezio</p> <p>2015-09-08</p> <p>We report that the recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum T<sub>c</sub> ≃ 1.2 K which decreases upon increasing the pressure. In the intermediate pressure region (3.5≲ p ≲ 7 kbar) the superconducting and the magnetic volume fractions are spatially <span class="hlt">phase</span> <span class="hlt">separated</span> and compete for <span class="hlt">phase</span> volume. Our results indicate that the less conductive magnetic <span class="hlt">phase</span> provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (T<sub>c</sub>) and of the superfluid density (ρ<sub>s</sub>). A scaling of ρ<sub>s</sub> with T<sub>c</sub><sup>3.2</sup> as well as the <span class="hlt">phase</span> <span class="hlt">separation</span> between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950058801&hterms=design+management&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddesign%2Bmanagement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950058801&hterms=design+management&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddesign%2Bmanagement"><span id="translatedtitle">Application of capillary fluid management techniques to the design of a <span class="hlt">phase</span> <span class="hlt">separating</span> microgravity bioreactor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Finger, Barry W.; Neville, Gale E., Jr.; Sager, John C.</p> <p>1993-01-01</p> <p>Manned space missions require the development of compact, efficient, and reliable life support systems. A number of aqueous biological conversion processes are associated with bioregenerative life support systems. Vessels, or bioreactors, capable of supporting these processes in microgravity must be developed. An annular flow bioreactor has been conceived. It has the potential to incorporate containment, <span class="hlt">phase</span> <span class="hlt">separation</span>, gas exchange, and illumination into a single vessel. The bioreactor utilizes capillary fluid management techniques and is configured as a cylindrical tube in which a two-<span class="hlt">phase</span> liquid-gas flow is maintained. Vanes placed around the inner perimeter enhance capillary forces and cause the liquid <span class="hlt">phase</span> to attach and flow along the interior surface of the tube. No physical barrier is required to complete <span class="hlt">phase</span> <span class="hlt">separation</span>. It is shown analytically that liquid film thickness is limited only by vane geometry and that an annular flow bioreactor capable of managing 284 liters would occupy 0.7 cubic m, less than half the volume of a Spacelab experiment rack.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21304517','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21304517"><span id="translatedtitle">Electronic <span class="hlt">phase</span> <span class="hlt">separation</span> at the LaAlO₃/SrTiO₃ interface.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ariando; Wang, X; Baskaran, G; Liu, Z Q; Huijben, J; Yi, J B; Annadi, A; Barman, A Roy; Rusydi, A; Dhar, S; Feng, Y P; Ding, J; Hilgenkamp, H; Venkatesan, T</p> <p>2011-02-08</p> <p>There are many electronic and magnetic properties exhibited by complex oxides. Electronic <span class="hlt">phase</span> <span class="hlt">separation</span> (EPS) is one of those, the presence of which can be linked to exotic behaviours, such as colossal magnetoresistance, metal-insulator transition and high-temperature superconductivity. A variety of new and unusual electronic <span class="hlt">phases</span> at the interfaces between complex oxides, in particular between two non-magnetic insulators LaAlO(3) and SrTiO(3), have stimulated the oxide community. However, no EPS has been observed in this system despite a theoretical prediction. Here, we report an EPS state at the LaAlO(3)/SrTiO(3) interface, where the interface charges are <span class="hlt">separated</span> into regions of a quasi-two-dimensional electron gas, a ferromagnetic <span class="hlt">phase</span>, which persists above room temperature, and a (superconductor like) diamagnetic/paramagnetic <span class="hlt">phase</span> below 60 K. The EPS is due to the selective occupancy (in the form of 2D-nanoscopic metallic droplets) of interface sub-bands of the nearly degenerate Ti orbital in the SrTiO(3). The observation of this EPS demonstrates the electronic and magnetic phenomena that can emerge at the interface between complex oxides mediated by the Ti orbital.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25423615','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25423615"><span id="translatedtitle">The relationship between oxygen permeability and <span class="hlt">phase</span> <span class="hlt">separation</span> morphology of the multicomponent silicone hydrogels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Zhengbai; Xie, Haijiao; An, Shuangshuang; Jiang, Yong</p> <p>2014-12-18</p> <p>In this article, the multicomponent copolymers were prepared by the copolymerization of two hydrophobic silicon-containing monomers bis(trimethylsilyloxy) methylsilylpropyl glycerol methacrylate (SiMA) and tris(trimethylsiloxy)-3-methacryloxypropylsilane (TRIS) with three hydrophilic monomers 2-hydroxyethyl methacrylate, N-vinylpyrrolidone, and N,N-dimethyl acrylamide. The copolymers were hydrated to form transparent silicone hydrogels. The oxygen permeability coefficients (Dk) of hydrogels were measured, and their relationships with the equilibrium water contents (EWC) and the types and contents of silicon containing monomers as well as the <span class="hlt">phase</span> <span class="hlt">separation</span> structures of silicone hydrogels were analyzed in detail. The results showed that the EWC decreased as the increase of SiMA content. The relationship between Dk and SiMA content, as well as that between Dk and EWC, showed inverted bell curve distributions, which meant two main factors, i.e., silicon-oxygen bond in silicone and water in hydrogel, contributed to oxygen permeation and followed a mutual inhibition competition mechanism. The internal morphologies of the hydrogels were observed by transmission electron microscope, and the results showed that the hydrogels presented two different <span class="hlt">phase</span> <span class="hlt">separation</span> structures depending on the types of the silicon-containing monomers. The silicone <span class="hlt">phase</span> in SiMA containing hydrogel presented to be a granular texture, while the silicone <span class="hlt">phase</span> in TRIS containing hydrogel formed a fibrous texture which resulted in a higher Dk value. These results could help to design a silicone hydrogel with better properties and wider application.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JSP...158..589B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JSP...158..589B"><span id="translatedtitle">Motility-Induced <span class="hlt">Phase</span> <span class="hlt">Separation</span> of Active Particles in the Presence of Velocity Alignment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barré, Julien; Chétrite, Raphaël; Muratori, Massimiliano; Peruani, Fernando</p> <p>2015-02-01</p> <p>Self-propelled particle (SPP) systems are intrinsically out of equilibrium systems, where each individual particle converts energy into work to move in a dissipative medium. When interacting through a velocity alignment mechanism, and with the medium acting as a momentum sink, even momentum is not conserved. In this scenario, a mapping into an equilibrium system seems unlikely. Here, we show that an entropy functional can be derived for SPPs with velocity alignment and density-dependent speed, at least in the (orientationally) disordered <span class="hlt">phase</span>. This non-trivial result has important physical consequences. The study of the entropy functional reveals that the system can undergo <span class="hlt">phase</span> <span class="hlt">separation</span> before the orientational-order <span class="hlt">phase</span> transition known to occur in SPP systems with velocity alignment. Moreover, we indicate that the spinodal line is a function of the alignment sensitivity and show that density fluctuations as well as the critical spatial diffusion, that leads to <span class="hlt">phase</span> <span class="hlt">separation</span>, dramatically increase as the orientational-order transition is approached.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1259706-pressure-induced-electronic-phase-separation-magnetism-superconductivity-cras','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1259706-pressure-induced-electronic-phase-separation-magnetism-superconductivity-cras"><span id="translatedtitle">Pressure-induced electronic <span class="hlt">phase</span> <span class="hlt">separation</span> of magnetism and superconductivity in CrAs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Khasanov, Rustem; Guguchia, Zurab; Eremin, Ilya; ...</p> <p>2015-09-08</p> <p>We report that the recent discovery of pressure (p) induced superconductivity in the binary helimagnet CrAs has raised questions on how superconductivity emerges from the magnetic state and on the mechanism of the superconducting pairing. In the present work the suppression of magnetism and the occurrence of superconductivity in CrAs were studied by means of muon spin rotation. The magnetism remains bulk up to p ≃ 3.5 kbar while its volume fraction gradually decreases with increasing pressure until it vanishes at p ≃ 7 kbar. At 3.5 kbar superconductivity abruptly appears with its maximum Tc ≃ 1.2 K which decreasesmore » upon increasing the pressure. In the intermediate pressure region (3.5≲ p ≲ 7 kbar) the superconducting and the magnetic volume fractions are spatially <span class="hlt">phase</span> <span class="hlt">separated</span> and compete for <span class="hlt">phase</span> volume. Our results indicate that the less conductive magnetic <span class="hlt">phase</span> provides additional carriers (doping) to the superconducting parts of the CrAs sample thus leading to an increase of the transition temperature (Tc) and of the superfluid density (ρs). A scaling of ρs with Tc3.2 as well as the <span class="hlt">phase</span> <span class="hlt">separation</span> between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23496518','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23496518"><span id="translatedtitle">Structure of <span class="hlt">phase-separated</span> athermal colloid-polymer systems in the protein limit.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mahynski, Nathan A; Irick, Barry; Panagiotopoulos, Athanassios Z</p> <p>2013-02-01</p> <p>Structural features of <span class="hlt">phase-separated</span> athermal colloid-polymer mixtures in the so-called "protein limit," where polymer chain dimensions exceed those of the colloid, are investigated using grand canonical Monte Carlo simulations on a fine lattice. Previous work [N. A. Mahynski et al., Phys. Rev. E 85, 051402 (2012)] has shown that this model accurately captures the <span class="hlt">phase</span> behavior of experimental systems, and that colloids with sufficiently small diameters, σ(c), relative to that of the monomeric segments, σ(s), <span class="hlt">phase</span> <span class="hlt">separate</span> more readily than their large-diameter counterparts. In the present study, we directly connect colloid and polymer structure with their <span class="hlt">phase</span> behavior by investigating these solutions along their binodal curves; we also explore the role of colloid surface curvature in destabilizing such solutions. Our findings suggest that simple consideration of an additional depletion radius, on the order of the σ(s), leads to a quantitatively accurate prediction of the division between stable and unstable ranges of d=σ(s)/σ(c). We compare these results to continuum models with different bonding potentials between monomer segments in order to elucidate the significance of the lattice model's bond fluctuations and inherently coarse colloid surface. In a number of cases, the continuum models deviate both qualitatively and quantitatively from the lattice results, but the binodals of the continuum models are presently not known, making a strong conclusion about these differences impossible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22581546','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22581546"><span id="translatedtitle"><span class="hlt">Phase</span> <span class="hlt">separated</span> behavior in yttrium doped CaMnO{sub 3}</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sharma, Neetika; Das, A.; Prajapat, C.L.; Kumar, Amit; Singh, M.R.</p> <p>2016-05-15</p> <p>Highlights: • Electron doped manganite. • Magnetic <span class="hlt">phase</span> <span class="hlt">separation</span> observed. • Structural transition coupled with magnetic transition. - Abstract: The effect of electron doping on the structural, transport, and magnetic properties of Mn (IV)—rich Ca{sub 1−x}Y{sub x}MnO{sub 3} (x ≤ 0.2) samples have been investigated using neutron diffraction, neutron depolarization, magnetization and resistivity techniques. The temperature dependence of resistivity follows the small polaron model and the activation energy exhibits a minimum for x = 0.1 sample. A <span class="hlt">phase</span> <span class="hlt">separated</span> magnetic ground state consisting of ferromagnetic domains (∼7 μm) embedded in G-type antiferromagnetic matrix is observed in the sample, x = 0.1. The transition to the long-range magnetically ordered state in this sample is preceded by a Griffith’s <span class="hlt">phase</span>. On lowering temperature below 300 K a structural transition from orthorhombic structure (Pnma) to a monoclinic structure (P2{sub 1}/m) is observed in the case of x = 0.2 sample. The ferromagnetic behavior in this case is suppressed and the antiferromagnetic ordering is described by coexisting C-type and G-type magnetic structures corresponding to the monoclinic and orthorhombic <span class="hlt">phases</span>, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27329167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27329167"><span id="translatedtitle">Recent development in liquid chromatography stationary <span class="hlt">phases</span> for <span class="hlt">separation</span> of Traditional Chinese Medicine components.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jin, Hongli; Liu, Yanfang; Guo, Zhimou; Wang, Jixia; Zhang, Xiuli; Wang, Chaoran; Liang, Xinmiao</p> <p>2016-10-25</p> <p>Traditional Chinese Medicine (TCM) is an ancient medical practice which has been used to prevent and cure diseases for thousands of years. TCMs are frequently multi-component systems with mainly unidentified constituents. The study of the chemical compositions of TCMs remains a hotspot of research. Different strategies have been developed to manage the significant complexity of TCMs, in an attempt to determine their constituents. Reversed-<span class="hlt">phase</span> liquid chromatography (RPLC) is still the method of choice for the <span class="hlt">separation</span> of TCMs, but has many problems related to limited selectivity. Recently, enormous efforts have been concentrated on the development of efficient liquid chromatography (LC) methods for TCMs, based on selective stationary <span class="hlt">phases</span>. This can improve the resolution and peak capacity considerably. In addition, high-efficiency stationary <span class="hlt">phases</span> have been applied in the analysis of TCMs since the invention of ultra high-performance liquid chromatography (UHPLC). This review describes the advances in LC methods in TCM research from 2010 to date, and focuses on novel stationary <span class="hlt">phases</span>. Their potential in the <span class="hlt">separation</span> of TCMs using relevant applications is also demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11258766','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11258766"><span id="translatedtitle">Use of vancomycin silica stationary <span class="hlt">phase</span> in packed capillary electrochromatography I. Enantiomer <span class="hlt">separation</span> of basic compounds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Desiderio, C; Aturki, Z; Fanali, S</p> <p>2001-02-01</p> <p>Chiral <span class="hlt">separation</span> of basic compounds was achieved by using 75 or 100 microm ID fused-silica capillaries packed with a vanoomycin-modified diol silica stationary <span class="hlt">phase</span>. The capillary was firstly packed for about 12 cm with a slurry mixture composed of diolsilica (3:1) then with the vancomycin modified diol-silica (3:1) (23 cm), and finally with diol-silica (3:1) for about 2 cm. Frits were prepared by a heating wire at the two ends of the capillary; the detector window was prepared at 8.5 cm from the end of the capillary where vancomycin was not present. The influence of the mobile <span class="hlt">phase</span> composition (pH and concentration, organic modifier type and concentration) on the velocity of the electroosmotic flow, chiral resolution and enantioselectivity was studied. Good enantiomeric resolution was achieved for atenolol, oxprenolol, propranolol, and venlafaxine using a mobile <span class="hlt">phase</span> composition of 100 mM ammonium acetate solution (pH 6)/water/acetonitrile (5:5:90 v/v/v) while for terbutaline a mixture of 5:15:80 v/v/v provided the best <span class="hlt">separations</span>. The use of methanol instead of acetonitrile caused a general increase of enantiomer resolution of the studied compounds together with a reduction of efficiency and detector response. However, the combination of acetonitrile and methanol in the mobile <span class="hlt">phase</span> (as, e.g., 10% methanol and 80% acetonitrile) allowed to improve the enantiomer resolution with satisfactory detector response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21924727','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21924727"><span id="translatedtitle">High performance liquid chromatographic <span class="hlt">separations</span> of gas oil samples and their hydrotreated products using commercial normal <span class="hlt">phases</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oro, Nicole E; Lucy, Charles A</p> <p>2011-10-28</p> <p>Three commercially available high performance liquid chromatography columns are used in normal <span class="hlt">phase</span> or quasi-normal <span class="hlt">phase</span> mode for the <span class="hlt">separation</span> of gas oil samples. The columns are tested with 20 analytical standards to determine their suitability for <span class="hlt">separations</span> of petroleum samples and their ability to <span class="hlt">separate</span> the nitrogen group-types (pyrrole and pyridine) found in petroleum. The columns studied are polymeric hypercrosslinked polystyrene (HGN), a biphenyl <span class="hlt">phase</span>, and a Chromegabond "DNAP" column from ES Industries. The HGN column <span class="hlt">separates</span> gas oils based on both ring structure and heteroatom, while the biphenyl <span class="hlt">phase</span> has low retention of most compounds studied in quasi-normal <span class="hlt">phase</span> mode. The "DNAP" column is selective for nitrogen-containing compounds, <span class="hlt">separating</span> them from PAHs as well as oxygen and sulphur compounds. Retention data of standards on all three columns is shown, along with chromatograms of gas oil samples on the HGN and "DNAP" columns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/889702','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/889702"><span id="translatedtitle">Heterogeneity of the Liquid <span class="hlt">Phase</span>, and Vapor <span class="hlt">Separation</span> in Los Azufres (Mexico) Geothermal Reservoir</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nieva, D.; Quijano, L.; Garfias, A.; Barragan, R.M.; Laredo, F.</p> <p>1983-12-15</p> <p>Data of chemical and isotopic composition of fluids from Los Azufres geothermal wells is interpreted in order to characterize the composition of the liquid <span class="hlt">phase</span>, and to define the relation between this <span class="hlt">phase</span> and fluids from steam-producing wells. Chemical and specific enthalpy data show that most wells considered are fed a mixture of steam and liquid. Thus, flashing occurs in the formation. This poses a problem on the interpretation of isotopic data, because the composition of the feeding mixture need not be representative of the composition of the liquid <span class="hlt">phase</span> in the reservoir. Two extreme alternatives for the interpretation of isotopic data are considered. In the first alternative the composition of the total discharge is considered to be the same as that of the liquid in the reservoir. In the second alternative the feeding fluid is considered to be a mixture of the liquid <span class="hlt">phase</span> in the reservoir and the calculated fraction of steam. In addition, this steam is assumed to <span class="hlt">separate</span> from a much larger mass of that liquid <span class="hlt">phase</span> at the downhole temperature. The contribution of steam is then subtracted from the total discharge to yield the composition of the liquid <span class="hlt">phase</span>. Using data for silica concentration in total discharge and <span class="hlt">separated</span> water, the chloride concentration in the reservoir liquid is calculated. This result is used to calculate the fraction of steam in the feeding mixture of each well. The isotopic data is then corrected as proposed for the second alternative, to yield the composition of the liquid <span class="hlt">phase</span>. Comparison of the corrected and uncorrected isotopic values shows that the correction has an important effect only when the steam mass fraction in the feeding mixture is large (> 20%). The correction tends to reduce the dispersion of data points in a {delta} D vs {delta}{sup 18}O diagram. Points representing composition of liquid <span class="hlt">phase</span> show an approximately linear distribution, suggesting a process of mixing of two fluids. Available data appears to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21359343','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21359343"><span id="translatedtitle">Nanoconfinement crystallization of <span class="hlt">frustrated</span> alkyl groups: crossover of mesophase to crystalline structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shi, Haifeng; Wang, Haixia; Xin, John H; Zhang, Xingxiang; Wang, Dujin</p> <p>2011-04-07</p> <p>Crossover of mesophase to crystalline structure in the nanoconfinement crystallization process of <span class="hlt">frustrated</span> side groups elucidates the critical crystal thickness d(c) or the length scale of side groups, which defines the transition process from mesophase (hexagonal and monoclinic <span class="hlt">phase</span>) to crystalline <span class="hlt">phase</span> (orthorhombic <span class="hlt">phase</span>) of confined CH(2) sequences in a given crystal size restriction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1239535','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1239535"><span id="translatedtitle">Dynamic evolution of liquid-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> during continuous cooling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Imhoff, S. D.; Gibbs, P. J.; Katz, M. R.; Ott, T. J.; Patterson, B. M.; Lee, W. -K.; Fezzaa, K.; Cooley, J. C.; Clarke, A. J.</p> <p>2015-03-01</p> <p>Solidification from a multiphase fluid involves many unknown quantities due to the difficulty of predicting the impact of fluid flow on chemical partitioning. Real-time x-ray radiography has been used to observe liquideliquid <span class="hlt">phase</span> <span class="hlt">separation</span> in Al90In10 prior to solidification. Quantitative image analysis has been used to measure the motion and population characteristics of the dispersed indium-rich liquid <span class="hlt">phase</span> during cooling. Here we determine that the droplet growth characteristics resemble well known steady-state coarsening laws with likely enhancement by concurrent growth due to supersaturation. Simplistic views of droplet motion are found to be insufficient until late in the reaction due to a hydrodynamic instability caused by the large density difference between the dispersed and matrix liquid <span class="hlt">phases</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1238610-dynamic-evolution-liquidliquid-phase-separation-during-continuous-cooling','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1238610-dynamic-evolution-liquidliquid-phase-separation-during-continuous-cooling"><span id="translatedtitle">Dynamic evolution of liquid–liquid <span class="hlt">phase</span> <span class="hlt">separation</span> during continuous cooling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Imhoff, Seth D.; Gibbs, Paul J.; Katz, Martha R.; ...</p> <p>2015-01-06</p> <p>Solidification from a multiphase fluid involves many unknown quantities due to the difficulty of predicting the impact of fluid flow on chemical partitioning. Real-time x-ray radiography was used to observe liquid-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> in Al90In10 prior to solidification. Quantitative image analysis was used to measure the motion and population characteristics of the dispersed indium-rich liquid <span class="hlt">phase</span> during cooling. Here we determine that the droplet growth characteristics resemble well known steady-state coarsening laws with likely enhancement by concurrent growth due to supersaturation. Simplistic views of droplet motion are found to be insufficient until late in the reaction due to a hydrodynamicmore » instability caused by the large density difference between the dispersed and matrix liquid <span class="hlt">phases</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16186910','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16186910"><span id="translatedtitle">Thermomorphic <span class="hlt">phase</span> <span class="hlt">separation</span> in ionic liquid-organic liquid systems--conductivity and spectroscopic characterization.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W; van Hal, Roy; Wasserscheid, Peter</p> <p>2005-08-21</p> <p>Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine <span class="hlt">phase</span> behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium ionic liquid/1-hexanol system are performed in the temperature interval 25-80 degrees C using a specially constructed double-electrode cell. In addition, FT-Raman and 1H-NMR spectroscopic studies performed on the <span class="hlt">phase-separable</span> system in the same temperature interval confirm the mutual solubility of the components in the system, the liquid-liquid equilibrium <span class="hlt">phase</span> diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6889376','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6889376"><span id="translatedtitle">Intensive use of biomass feedstock in ethanol conversion: The alcohol-water, vapor-<span class="hlt">phase</span> <span class="hlt">separation</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Robertson, G.H.; Doyle, L.R.; Pavlath, A.E.</p> <p>1983-12-01</p> <p>Fermentation of ethanol in a system whereby the biomass is used intensively (both to <span class="hlt">separate</span> alcohol from water by vapor <span class="hlt">phase</span> adsorption and to serve as the feedstock) is shown to be possible on theoretical grounds when the biomass is grain. The rationale for a vapor-<span class="hlt">phase</span> adsorption process as an alternative to distillation is shown to be energetically valid above 84 wt % ethanol. The capacity of grain in new vapor-<span class="hlt">phase</span> ambient adsorption processes was estimated experimentally with the finding that sufficient capacity exists for the intensive use but that the adsorption is dynamically controlled so that the grain form and particle size are important. Pretreatments such as explosive dehydration improve the transfer of water to the grain in adsorption with potential improvement in the efficiency of liquefaction and saccharification. At room temperature, these sorbents are not perfectly selective for water but adsorb ethanol which will be carried to the liquefaction, saccharification, and fermentation with the feedstock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16965092','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16965092"><span id="translatedtitle">Gas-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> in oppositely charged colloids: stability and interfacial tension.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fortini, Andrea; Hynninen, Antti-Pekka; Dijkstra, Marjolein</p> <p>2006-09-07</p> <p>We study the <span class="hlt">phase</span> behavior and the interfacial tension of the screened Coulomb (Yukawa) restricted primitive model (YRPM) of oppositely charged hard spheres with diameter sigma using Monte Carlo simulations. We determine the gas-liquid and gas-solid <span class="hlt">phase</span> transitions using free energy calculations and grand-canonical Monte Carlo simulations for varying inverse Debye screening length kappa. We find that the gas-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> is stable for kappasigma<or=4, and that the critical temperature decreases upon increasing the screening of the interaction (decreasing the range of the interaction). In addition, we determine the gas-liquid interfacial tension using grand-canonical Monte Carlo simulations. The interfacial tension decreases upon increasing the range of the interaction. In particular, we find that simple scaling can be used to relate the interfacial tension of the YRPM to that of the restricted primitive model, where particles interact with bare Coulomb interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1238610','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1238610"><span id="translatedtitle">Dynamic evolution of liquid–liquid <span class="hlt">phase</span> <span class="hlt">separation</span> during continuous cooling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Imhoff, Seth D.; Gibbs, Paul J.; Katz, Martha R.; Ott, Thomas J.; Patterson, Brian M.; Lee, Wah-Keat; Fezzaa, Kamel; Cooley, Jason C.; Clarke, Amy J.</p> <p>2015-01-06</p> <p>Solidification from a multiphase fluid involves many unknown quantities due to the difficulty of predicting the impact of fluid flow on chemical partitioning. Real-time x-ray radiography was used to observe liquid-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> in Al<sub>90</sub>In<sub>10</sub> prior to solidification. Quantitative image analysis was used to measure the motion and population characteristics of the dispersed indium-rich liquid <span class="hlt">phase</span> during cooling. Here we determine that the droplet growth characteristics resemble well known steady-state coarsening laws with likely enhancement by concurrent growth due to supersaturation. Simplistic views of droplet motion are found to be insufficient until late in the reaction due to a hydrodynamic instability caused by the large density difference between the dispersed and matrix liquid <span class="hlt">phases</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21528948','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21528948"><span id="translatedtitle">Condensed ground states of <span class="hlt">frustrated</span> Bose-Hubbard models</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moeller, G.; Cooper, N. R.</p> <p>2010-12-15</p> <p>We study theoretically the ground states of two-dimensional Bose-Hubbard models which are <span class="hlt">frustrated</span> by gauge fields. Motivated by recent proposals for the implementation of optically induced gauge potentials, we focus on the situation in which the imposed gauge fields give rise to a pattern of staggered fluxes of magnitude {alpha} and alternating in sign along one of the principal axes. For {alpha}=1/2 this model is equivalent to the case of uniform flux per plaquette n{sub {phi}=}1/2, which, in the hard-core limit, realizes the 'fully <span class="hlt">frustrated</span>' spin-1/2 XY model. We show that the mean-field ground states of this <span class="hlt">frustrated</span> Bose-Hubbard model typically break translational symmetry. Given the presence of both a non-zero superfluid fraction and translational symmetry breaking, these <span class="hlt">phases</span> are supersolid. We introduce a general numerical technique to detect broken symmetry condensates in exact diagonalization studies. Using this technique we show that, for all cases studied, the ground state of the Bose-Hubbard model with staggered flux {alpha} is condensed, and we obtain quantitative determinations of the condensate fraction. We discuss the experimental consequences of our results. In particular, we explain the meaning of gauge invariance in ultracold-atom systems subject to optically induced gauge potentials and show how the ability to imprint <span class="hlt">phase</span> patterns prior to expansion can allow very useful additional information to be extracted from expansion images.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1068840','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1068840"><span id="translatedtitle"><span class="hlt">Phase-separated</span>, epitaxial composite cap layers for electronic device applications and method of making the same</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Aytug, Tolga [Knoxville, TN; Paranthaman, Mariappan Parans [Knoxville, TN; Polat, Ozgur [Knoxville, TN</p> <p>2012-07-17</p> <p>An electronic component that includes a substrate and a <span class="hlt">phase-separated</span> layer supported on the substrate and a method of forming the same are disclosed. The <span class="hlt">phase-separated</span> layer includes a first <span class="hlt">phase</span> comprising lanthanum manganate (LMO) and a second <span class="hlt">phase</span> selected from a metal oxide (MO), metal nitride (MN), a metal (Me), and combinations thereof. The <span class="hlt">phase-separated</span> material can be an epitaxial layer and an upper surface of the <span class="hlt">phase-separated</span> layer can include interfaces between the first <span class="hlt">phase</span> and the second <span class="hlt">phase</span>. The <span class="hlt">phase-separated</span> layer can be supported on a buffer layer comprising a composition selected from the group consisting of IBAD MgO, LMO/IBAD-MgO, homoepi-IBAD MgO and LMO/homoepi-MgO. The electronic component can also include an electronically active layer supported on the <span class="hlt">phase-separated</span> layer. The electronically active layer can be a superconducting material, a ferroelectric material, a multiferroic material, a magnetic material, a photovoltaic material, an electrical storage material, and a semiconductor material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21770593','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21770593"><span id="translatedtitle">Magnetostructural transitions in a <span class="hlt">frustrated</span> magnet at high fields.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tsurkan, V; Zherlitsyn, S; Felea, V; Yasin, S; Skourski, Yu; Deisenhofer, J; von Nidda, H-A Krug; Lemmens, P; Wosnitza, J; Loidl, A</p> <p>2011-06-17</p> <p>Ultrasound and magnetization studies of bond-<span class="hlt">frustrated</span> ZnCr(2)S(4) spinel are performed in static magnetic fields up to 18 T and in pulsed fields up to 62 T. At temperatures below the antiferromagnetic transition at T(N1)≈14  K, the sound velocity as a function of the magnetic field reveals a sequence of steps followed by plateaus indicating a succession of crystallographic structures with constant stiffness. At the same time, the magnetization evolves continuously with a field up to full magnetic polarization without any plateaus in contrast to geometrically <span class="hlt">frustrated</span> chromium oxide spinels. The observed high-field magnetostructural states are discussed within a H-T <span class="hlt">phase</span> diagram taking into account the field and temperature evolution of three coexisting spin structures and subsequent lattice transformations induced by the magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27650633','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27650633"><span id="translatedtitle">Two-<span class="hlt">phase</span> anaerobic digestion of vegetable market waste fraction of municipal solid waste and development of improved technology for <span class="hlt">phase</span> <span class="hlt">separation</span> in two-<span class="hlt">phase</span> reactor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Majhi, Bijoy Kumar; Jash, Tushar</p> <p>2016-12-01</p> <p>Biogas production from vegetable market waste (VMW) fraction of municipal solid waste (MSW) by two-<span class="hlt">phase</span> anaerobic digestion system should be preferred over the single-stage reactors. This is because VMW undergoes rapid acidification leading to accumulation of volatile fatty acids and consequent low pH resulting in frequent failure of digesters. The weakest part in the two-<span class="hlt">phase</span> anaerobic reactors was the techniques applied for solid-liquid <span class="hlt">phase</span> <span class="hlt">separation</span> of digestate in the first reactor where solubilization, hydrolysis and acidogenesis of solid organic waste occur. In this study, a two-<span class="hlt">phase</span> reactor which consisted of a solid-<span class="hlt">phase</span> reactor and a methane reactor was designed, built and operated with VMW fraction of Indian MSW. A robust type filter, which is unique in its implementation method, was developed and incorporated in the solid-<span class="hlt">phase</span> reactor to <span class="hlt">separate</span> the process liquid produced in the first reactor. Experiments were carried out to assess the long term performance of the two-<span class="hlt">phase</span> reactor with respect to biogas production, volatile solids reduction, pH and number of occurrence of clogging in the filtering system or choking in the process liquid transfer line. The system performed well and was operated successfully without the occurrence of clogging or any other disruptions throughout. Biogas production of 0.86-0.889m(3)kg(-1)VS, at OLR of 1.11-1.585kgm(-3)d(-1), were obtained from vegetable market waste, which were higher than the results reported for similar substrates digested in two-<span class="hlt">phase</span> reactors. The VS reduction was 82-86%. The two-<span class="hlt">phase</span> anaerobic digestion system was demonstrated to be stable and suitable for the treatment of VMW fraction of MSW for energy generation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23676903','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23676903"><span id="translatedtitle">Fabrication of poly(γ-glutamic acid) monolith by thermally induced <span class="hlt">phase</span> <span class="hlt">separation</span> and its application.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Sung-Bin; Fujimoto, Takashi; Mizohata, Eiichi; Inoue, Tsuyoshi; Sung, Moon-Hee; Uyama, Hiroshi</p> <p>2013-01-01</p> <p>Monoliths are functional porous materials with a three-dimensional continuous interconnected pore structure in a single piece. A monolith with uniform shape based on poly(γ-glutamic acid) (PGA) has been prepared via a thermally induced <span class="hlt">phase</span> <span class="hlt">separation</span> technique using a mixture of dimethyl sulfoxide, water, and ethanol as solvent. The morphology of the obtained monolith was observed by scanning electron microscopy and the surface area of the monolith was evaluated by the Brunauer Emmett Teller method. The effects of fabrication parameters such as the concentration and molecular mass of PGA and the solvent composition have been systematically investigated. The PGA monolith was cross-linked with hexamethylene diisocyanate to produce the water-insoluble monolith. The addition of sodium chloride to the <span class="hlt">phase</span> <span class="hlt">separation</span> solvent affected the properties of the cross-linked monolith. The swelling ratio of the cross-linked monolith toward aqueous solutions depended on the buffer pH as well as the monolith fabrication condition. Copper(II) ion was efficiently adsorbed on the cross-linked PGA monolith, and the obtained copper-immobilized monolith showed strong antibacterial activity for Escherichia coli. By combination of the characteristic properties of PGA (e.g., high biocompatibility and biodegradability) and the unique features of monoliths (e.g., through-pore structure, large surface area, and high porosity with small pore size), the PGA monolith possesses large potentials for various industrial applications in the biomedical, environmental, analytical, and <span class="hlt">separation</span> fields.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. Their policies may differ from this site.</small> </div> </center> <div id="footer-wrapper"> <div class="footer-content"> <div id="footerOSTI" class=""> <div class="row"> <div class="col-md-4 text-center col-md-push-4 footer-content-center"><small><a href="http://www.science.gov/disclaimer.html">Privacy and Security</a></small> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center col-md-pull-4 footer-content-left"> <img src="https://www.osti.gov/images/DOE_SC31.png" alt="U.S. Department of Energy" usemap="#doe" height="31" width="177"><map style="display:none;" name="doe" id="doe"><area shape="rect" coords="1,3,107,30" href="http://www.energy.gov" alt="U.S. Deparment of Energy"><area shape="rect" coords="114,3,165,30" href="http://www.science.energy.gov" alt="Office of Science"></map> <a ref="http://www.osti.gov" style="margin-left: 15px;"><img src="https://www.osti.gov/images/footerimages/ostigov53.png" alt="Office of Scientific and Technical Information" height="31" width="53"></a> <div class="visible-sm visible-xs push_footer"></div> </div> <div class="col-md-4 text-center footer-content-right"> <a href="http://www.osti.gov/nle"><img src="https://www.osti.gov/images/footerimages/NLElogo31.png" alt="National Library of Energy" height="31" width="79"></a> <a href="http://www.science.gov"><img src="https://www.osti.gov/images/footerimages/scigov77.png" alt="science.gov" height="31" width="98"></a> <a href="http://worldwidescience.org"><img src="https://www.osti.gov/images/footerimages/wws82.png" alt="WorldWideScience.org" height="31" width="90"></a> </div> </div> </div> </div> </div> <p><br></p> </div><!-- container --> </body> </html>